CN116601409A - Friction roller speed reducer - Google Patents

Abstract

The invention provides a structure capable of ensuring good transmission efficiency and preventing the acceleration of pressing force from increasing. The ring roller (5) is configured by combining a pair of roller elements (13 a, 13 b) by a connecting tube (14) so as to be capable of relative displacement in the axial direction and not capable of relative rotation. Elastic members (8) are disposed between the front end surfaces of the pair of roller elements (13 a, 13 b).

Description

Friction roller speed reducer

Technical Field

The present invention relates to a friction roller speed reducer that is incorporated in, for example, a drive system of an electric vehicle, and that reduces the rotation of an electric motor (increases torque) and then transmits the torque to drive wheels.

Background

In an electric vehicle, in order to increase the efficiency of an electric motor serving as a driving source and to extend the distance that can be traveled per charge, the rotation of an output shaft of a small electric motor that rotates at a high speed is decelerated by a speed reducer, and then transmitted to driving wheels. As such a speed reducer, a friction roller type speed reducer can be used.

Fig. 54 shows a friction roller speed reducer described in japanese patent application laid-open No. 2017-120121. The friction roller reducer 100 includes an input shaft 101, an output shaft 102, a sun roller 103, a ring roller 104, a plurality of intermediate rollers 105, and a loading cam device 106.

The output shaft 102 is supported coaxially with the input shaft 101 and is relatively rotatable with respect to the input shaft 101. The output shaft 102 has a flange portion 107 protruding radially outward at a portion on one side in the axial direction (left side in fig. 54).

The sun roller 103 has an inner diameter side rolling contact surface 108 having a circular arc cross-sectional shape (bus bar shape) on the outer peripheral surface. The sun roller 103 is provided integrally with the input shaft 101 at the end portion on the other axial side (right side in fig. 54) of the input shaft 101.

The ring roller 104 has an outer diameter side rolling contact surface 109 on the inner peripheral surface, and is disposed coaxially with the sun roller 103 around the sun roller 103. The ring roller 104 includes a pair of roller elements 110a and 110b and a coupling cylinder 111.

The pair of roller elements 110a and 110b each have inclined surface portions 112a and 112b on the inner peripheral surface, which are inclined in a direction to decrease the inner diameter as they are separated from each other in the axial direction, and have engaging concave-convex portions 113 on the tip portions facing each other. That is, the outer diameter side rolling contact surface 109 is constituted by inclined surface portions 112a, 112b of the pair of roller elements 110a, 110 b.

The pair of roller elements 110a and 110b are combined so as to be axially displaceable and not rotatable by engaging the engagement concave-convex portions 113 with each other. Further, of the pair of roller elements 110a and 110b, the roller element 110a on one axial side is prevented from being displaced to one axial side and from being rotated relative to the coupling cylinder 111 by the retainer ring 114 fitted in the one axial side portion of the coupling cylinder 111 and engaged with the inner peripheral surface of the one axial side end portion of the coupling cylinder 111. In contrast, the roller element 110b on the other axial side is fitted in the axial intermediate portion of the coupling cylinder 111 so as to be axially displaceable with respect to the coupling cylinder 111. That is, the pair of roller elements 110a, 110b and the coupling cylinder 111 integrally rotate.

Each of the plurality of intermediate rollers 105 includes a rolling surface 115 on the outer peripheral surface, and the rolling surface 115 has a circular arc cross-sectional shape (a busbar shape) and is in rolling contact with the inner diameter side rolling contact surface 108 and the outer diameter side rolling contact surface 109. The intermediate roller 105 is supported so as to be rotatable (autorotative) about its own center axis and displaceable in the radial direction about the center axis O of the input shaft 101 with respect to a bracket 116 supported by a portion of the housing or the like that does not rotate even when in use. That is, the intermediate rollers 105 are each rotatable, but are prevented from rotating (revolving) about the central axis of the input shaft 101.

The loading cam device 106 presses the pair of roller elements 110a, 110b in a direction to bring the pair of roller elements 110a, 110b closer to each other. The loading cam device 106 includes a roller element 110b on the other axial side, a cam plate 117, and a plurality of rolling elements 118.

The roller element 110b on the other side in the axial direction has driving-side cam surfaces 119 on the other side in the axial direction, each of which has the same number of concave portions and convex portions, alternately arranged in the circumferential direction.

The cam plate 117 includes a cylindrical portion 120, a side plate portion 121 bent outward in the radial direction from one axial end of the cylindrical portion 120, and a protruding portion 122 protruding outward in the axial direction from one circumferential position of the other axial end of the cylindrical portion 120. The side plate portion 121 has driven-side cam surfaces 123 on one side in the axial direction, each of which has the same number of concave portions and convex portions alternately arranged in the circumferential direction.

The cam plate 117 is fitted and supported to the end portion on the other side in the axial direction of the connecting tube 111 by an angular ball bearing 124 so as to be rotatable relative to the connecting tube 111 and not to be displaceable relative to the connecting tube 111 on the other side in the axial direction. The cam plate 117 is configured to fit the cylindrical portion 120 to the flange portion 107 of the output shaft 102 without rattling, and to engage the protruding portion 122 with an axial groove provided on the outer peripheral surface of the flange portion 107 of the output shaft 102 so as to be displaceable in the axial direction. That is, the output shaft 102 and the cam plate 117 are combined so as to be relatively displaceable in the axial direction and not relatively rotatable. In summary, the output shaft 102 and the cam plate 117 integrally rotate.

The plurality of rolling elements 118 are sandwiched between the driving side cam surface 119 and the driven side cam surface 123, respectively.

In the friction roller reducer 100, when the input shaft 101 is driven to rotate and the sun roller 103 is driven to rotate, the intermediate roller 105 rotates based on the rolling contact between the inner diameter side rolling contact surface 108 of the sun roller 103 and the rolling surface 115 of the intermediate roller 105. When the intermediate roller 105 rotates, the ring roller 104 rotates around the central axis O of the input shaft 101 due to the rolling contact between the rolling surface 115 of the intermediate roller 105 and the outer diameter side rolling contact surface 109 of the ring roller 104. Rotation of the ring roller 104 is transmitted to the output shaft 102 via the loading cam device 106.

Here, when the roller element 110b constituting the other axial side of the ring roller 104 rotates, the amount of jump from the bottom of the concave portion of the driving side cam surface 119 to the rolling element 118 of the loading cam device 106 and the amount of jump from the bottom of the concave portion of the driven side cam surface 123 increase. As a result, when the axial dimension of the loading cam device 106 increases, the pair of roller elements 110a and 110b are pressed in the directions approaching each other, the inner diameter of the portion of the inclined surface portions 112a and 112b constituting the outer diameter side rolling contact surface 109 that is in rolling contact with the rolling surface 115 becomes smaller. As a result, the surface pressure of the traction portion (rolling contact portion) between the outer diameter side rolling contact surface 109 and the rolling surface 115 increases. When the intermediate roller 105 is pressed inward in the radial direction around the center axis O of the input shaft 101 with this surface pressure increase, the surface pressure of the traction portion between the rolling surface 115 and the inner diameter side rolling contact surface 108 also increases. As a result, excessive slip is not generated in each traction portion, and the torque input from the input shaft 101 to the sun roller 103 can be transmitted to the ring roller 104 via the intermediate roller 105, and the torque can be taken out from the output shaft 102 via the loading cam device 106.

Prior art literature

Patent literature

Patent document 1: japanese patent application laid-open No. 2017-120121

Patent document 2: japanese patent laid-open publication 2016-223468

Patent document 3: japanese patent laid-open No. 2008-196657

Disclosure of Invention

Problems to be solved by the invention

The friction roller reducer 100 described in japanese patent application laid-open No. 2017-120121 has room for further improvement in terms of ensuring good transmission efficiency.

That is, in the friction roller reducer 100, if the surface pressure at the traction portion between the rolling surface 115 and the inner diameter side rolling contact surface 108 and the outer diameter side rolling contact surface 109 is insufficient, the transmission efficiency of the friction roller reducer 100 is lowered or remarkable, and in this case, there is a possibility that a harmful slip (excessive slip) called extreme slip is generated. When extreme slippage occurs, the rolling surface 115 and the inner diameter side rolling contact surface 108 and/or the outer diameter side rolling contact surface 109 are in direct rolling contact with each other with metal without passing through a film of traction oil, and the rolling surface 115 and the inner diameter side rolling contact surface 108 and/or the outer diameter side rolling contact surface 109 are significantly worn, so that the durability of the friction roller reducer 100 is significantly reduced. In order to prevent such extreme slip, an operation traction coefficient (= tangential force/normal force) representing an actual operation state is kept at a limit (maximum traction coefficient μ) _max ) The following are important, limits (maximum traction coefficient mu _max ) A limit value of the traction coefficient (=tangential force/normal force) representing a value capable of transmitting torque without generating extreme slip. However, the limiting traction coefficient μ _max But also by parameters other than torque that should be transmitted between the input shaft 101 and the output shaft 102.

For example, it is known that the traction coefficient varies according to the temperature (oil temperature) of traction oil supplied to the traction section. More specifically, in a normal temperature environment (for example, an environment of 0 ℃ or higher), as the oil temperature increases, the viscosity of the traction oil decreases, and thus the limiting traction coefficient also decreases. On the other hand, it is known that in an extremely low temperature environment (for example, an environment lower than 0 ℃), as described in japanese patent application laid-open publication No. 2016-223468 (patent document 2), as the oil temperature decreases, the viscosity of the traction oil increases, and the limiting traction coefficient decreases.

In addition, japanese patent application laid-open No. 2008-196657 (patent document 3) describes the following: the traction coefficient is represented by the peripheral speed U of the driven side rotator ₂ Peripheral speed U relative to the driving-side rotating body ₁ Slip S (= (U) ₁ －U ₂ )/U ₁ ) Is varied by the influence of (a).

In addition, as shown in fig. 55, it is known that the maximum limit traction coefficient μ _max As the surface pressure P of the traction portion becomes larger, it becomes larger.

In order to transmit torque from the sun roller 103 to the ring roller 104 without generating extreme slip in each traction portion irrespective of the influence of parameters other than torque to be transmitted between the input shaft 101 and the output shaft 102, such as the oil temperature of the traction oil, the peripheral speed and the surface pressure of the traction portion, the limit traction coefficient μ is set high and ensured to a large extent _max The difference or ratio (safety ratio) with respect to the running traction coefficient μ, the safety ratio with respect to the traction coefficient is effective. However, if the safety factor related to the traction coefficient is too high, the surface pressure of each traction portion may become too large in order to suppress the running traction coefficient μ to be small, and the rolling resistance may excessively increase. As a result, there is a possibility that the transmission loss increases, and the transmission efficiency of the friction roller reducer 100 decreases.

If the structure is such that the pair of roller elements are pressed in the direction in which the pair of roller elements are brought close to each other by the pressing device that includes the driver such as the hydraulic pump and the electric motor and is capable of adjusting the pressing force to an arbitrary magnitude, the influence of parameters other than the torque to be transmitted between the input shaft 101 and the output shaft 102, such as the oil temperature of the traction oil, the peripheral speed of the traction portion, the surface pressure, and the like, is also considered, and the surface pressure of the traction portion can be adjusted to an appropriate magnitude. As a result, the occurrence of extreme slip can be prevented, and the transmission loss can be suppressed to be small. However, in such a structure, since the driver for driving the pressing device is provided separately from the driving source of the input shaft, there is a possibility that the friction roller speed reducer as a whole becomes large or complex. And/or, since energy loss is also generated in the driver, there is a possibility that the efficiency of the friction roller speed reducer as a whole is lowered.

As another method, a method of researching a lead angle of a driving side cam surface and/or a driven side cam surface of the loading cam device or an inclination angle of inclined surface portions of a pair of roller elements constituting the ring roller is also considered. That is, as shown in fig. 55, the greater the surface pressure P of the traction portion is, the greater the maximum limit traction coefficient μ _max As the torque transmitted by the friction roller reducer increases, the surface pressure of the traction portion becomes excessively large. Therefore, when the torque transmitted by the friction roller reducer is large, the lead angle of the driving side cam surface and/or the driven side cam surface or the inclination angle of the inclined surface portion of the roller element is limited so as to suppress the rise of the pressing force of the loading cam device or reduce the pressing force, and when the surface pressure of the traction portion is set to an appropriate value, the occurrence of extreme slip can be prevented, and the transmission loss can be suppressed to be small. However, in the case of adopting such a structure, it is necessary to determine the lead angle or the inclination angle in consideration of elastic deformation of the roller element, the cam plate, and the like, which are caused by torque transmission, and manufacturing errors of the above-described members, and there are problems that high shape accuracy and low mass productivity are required.

When the friction roller reducer 100 is operated and the center axis of the intermediate roller 105 is inclined with respect to the center axis of the ring roller 104, if the intermediate roller 105 rotates and is deflected, a force (deflection force) in a direction perpendicular to the tangential directions (torque transmission direction, rolling direction) of the outer diameter side rolling contact surface 109 and the rolling surface 115 is applied to the outer diameter side rolling contact surface 109 and the rolling surface 115. Further, the deflection force is proportional to the magnitude of the force (tangential force, torque) transmitted at the traction portion between the outer diameter side rolling contact surface 109 and the rolling surface 115. The above-described deflection force has an axial component as the same direction as the direction in which the loading cam device 106 presses the pair of roller elements 110a, 110 b. Therefore, when the intermediate roller 105 is deflected, the pressing force of the outer diameter side rolling contact surface 109 against the rolling surface 115 changes.

Here, when the traction coefficient of the traction portion in the direction perpendicular to the torque transmission direction is constant, the above-described deflection force at the traction portion between the outer diameter side rolling contact surface 109 and the rolling surface 115 increases as the pressing force of the outer diameter side rolling contact surface 109 against the rolling surface 115 increases. In other words, if the intermediate roller 105 is deflected, the pressing force of the outer diameter side rolling contact surface 109 against the rolling surface 115 may be increased in an accelerated manner. If the pressing force of the outer diameter side rolling contact surface 109 against the rolling surface 115 becomes excessively large, there is a possibility that the transmission efficiency of the friction roller reducer 100 is lowered, or damage such as heat generation and sticking occurs. Further, when the amount of displacement of the roller element 110b on the other side in the axial direction increases toward one side in the axial direction with an increase in the pressing force of the outer diameter side rolling contact surface 109 against the rolling surface 115, the rolling elements 118 may be separated (jumped up) from the driving side cam surface 119 and/or the driven side cam surface 123.

The rate of increase in the pressing force based on the occurrence of the deflection of the intermediate roller 105 is determined by the inclination angle of the inclined surface portions 112a and 112b with respect to the central axis O of the input shaft 101. Therefore, by increasing the inclination angle of the inclined surface portions 112a and 112b (making the inclination steep), the rate of increase of the pressing force can be suppressed to be low.

However, if the inclination angle of the inclined surface portions 112a, 112b is increased, the circumferential speed difference between the contact ellipse at both ends in the longitudinal direction of the traction portion between the outer diameter side rolling contact surface 109 and the rolling surface 115 becomes large, and the differential slip at the traction portion becomes large, which causes a problem that the transmission efficiency of the friction roller reducer 100 is lowered. When the inclination angle of the inclined surface portions 112a and 112b is increased, the pair of roller elements 110a and 110b is pressed by the loading cam device 106 in a direction to bring the pair of roller elements 110a and 110b closer to each other, and based on this, the normal force acting on the traction portion between the outer diameter side rolling contact surface 109 and the rolling surface 115 becomes smaller. Therefore, in order to obtain a desired normal force, the pressing force that should be generated by the loading cam device 106 becomes large, and there is a problem in that the loading cam device 106 becomes large.

The following methods are also contemplated: the flange portion protruding radially inward is provided at the end portion of the small diameter side of the roller element, and the axial side surface of the flange portion is opposed to the axial side surface of the intermediate roller, whereby the roller element is prevented from being excessively displaced in the axial direction. However, in such a structure, the pressing force of the outer diameter side rolling contact surface against the rolling surface becomes excessive until the axial side surface of the flange portion comes into contact with the axial side surface of the intermediate roller, and thus the reduction of the transmission efficiency of the friction roller reducer cannot be prevented. Further, due to sliding of the axial side surface of the flange portion with respect to the axial side surface of the intermediate roller, there is a possibility that damage such as friction loss or heat generation adhesion may occur.

In view of the above, an object of the present invention is to realize a structure of a friction roller reducer that can satisfactorily ensure transmission efficiency and can prevent an increase in the acceleration of pressing force.

Means for solving the problems

The friction roller speed reducer according to an aspect of the present invention includes a sun roller, a ring roller, a plurality of intermediate rollers, a pressing device, and an elastic member.

The ring roller is disposed coaxially with the sun roller around the sun roller.

The plurality of intermediate rollers have rolling surfaces on the outer peripheral surface, the rolling surfaces being in rolling contact with the sun roller and the ring roller.

The sun roller or the ring roller has a pair of roller elements supported so as to be axially relatively displaceable, and the pair of roller elements includes inclined surface portions which are inclined in a direction approaching the intermediate roller in the radial direction as they are separated from each other in the axial direction, on the peripheral surface in rolling contact with the rolling surface, that is, on the outer peripheral surface in the case of the sun roller and on the inner peripheral surface in the case of the ring roller.

The pressing device presses the pair of roller elements in a direction to bring the pair of roller elements closer to each other.

The elastic member is disposed between the pair of roller elements and elastically biases the pair of roller elements in a direction away from the rolling surface of the intermediate roller.

In the friction roller speed reducer according to an aspect of the present invention, the pressing device may be constituted by a loading cam device.

In the friction roller speed reducer according to an aspect of the present invention, the rolling surface may include: a pair of intermediate roller side inclined surfaces which are disposed at both axial side portions, incline in a direction in which the outer diameter becomes smaller as the axial direction is directed to the direction of mutual separation, and are in rolling contact with the inclined surfaces; and a connecting surface portion which is disposed in the axial intermediate portion, has an outer diameter which does not change in the axial direction or has a generatrix with a radius of curvature larger than that of the generatrix of the intermediate roller-side inclined portion, and is in rolling contact with the other roller of the sun roller and the ring roller.

In the friction roller speed reducer according to an aspect of the present invention, the pair of intermediate roller side inclined surface portions may have a circular arc shape or a linear busbar shape.

In the friction roller speed reducer according to an aspect of the present invention, a gap may be provided between the elastic member and at least one of the pair of roller elements in an initial state before the pressing device exerts the pressing force.

In the friction roller speed reducer according to an aspect of the present invention, the elastic member may be constituted by one or more belleville springs, and the thickness of the belleville spring is t and the total deflection is h ₀ In the case of (2), h can be ₀ And/t is 1.0 or less.

In the friction roller reducer according to an aspect of the present invention, the ring roller may include the pair of roller elements, and the pair of roller elements may have the inclined surface portion inclined in a direction in which the inner diameter becomes smaller as the pair of roller elements are separated from each other in the axial direction.

In the friction roller speed reducer according to an aspect of the present invention, the elastic member may have two belleville springs that are combined so as to have an opening on the inner diameter side and have a substantially V-shaped cross section.

Alternatively, in the friction roller speed reducer according to an aspect of the present invention, the elastic member may have two belleville springs that are combined so as to have an opening on the outer diameter side and have a substantially V-shaped cross section.

In the friction roller reducer according to an aspect of the present invention, the ring roller may include a coupling cylinder that supports the pair of roller elements so as to be axially relatively displaceable and so as not to be relatively rotatable.

In the friction roller speed reducer according to an aspect of the present invention, the connecting tube may have an opening portion that opens on an inner peripheral surface and an outer peripheral surface.

The opening may have a size capable of visually inspecting end surfaces of the pair of roller elements facing each other from a radially outer side of the connecting tube.

The opening may have a size that enables the elastic member to visually contact the pair of roller elements from the radially outer side of the connecting tube.

The opening portion may form an oil drain hole.

The connecting tube may have the openings at a plurality of positions equally spaced in the circumferential direction.

In the friction roller speed reducer according to an aspect of the present invention, an oil discharge passage may be provided that communicates a radially inner side and a radially outer side of a space between the pair of roller elements, including the elastic member.

In the friction roller speed reducer according to an aspect of the present invention, the elastic member may be constituted by one or more belleville springs.

The elastic member may have a cutout opening at an outer peripheral edge and/or an inner peripheral edge, or may have a through hole penetrating a radially intermediate portion.

In one aspect of the present invention, the friction roller reducer may include a shim plate sandwiched between at least one of the pair of roller elements and the elastic member, and the shim plate may have grooves or ridges on an axial side surface thereof in a radial direction.

In one embodiment of the present invention, the friction roller reducer may include a tooth-shaped lock washer interposed between at least one of the pair of roller elements and the elastic member.

In the friction roller reducer according to an aspect of the present invention, at least one of the pair of roller elements may have a groove in a distal end surface in a radial direction.

In the friction roller speed reducer according to an aspect of the present invention, the elastic member may be formed of a wave washer.

Alternatively, in the friction roller speed reducer according to an aspect of the present invention, the elastic member may be constituted by a torsion coil spring.

In this case, the friction roller reducer according to an aspect of the present invention may include a retainer having a plurality of retaining holes penetrating in the axial direction at a plurality of positions in the circumferential direction, the retainer being disposed between the pair of roller elements, and the torsion coil springs may be retained in the retaining holes, respectively.

The effects of the invention are as follows.

According to the friction roller speed reducer of the present invention, the transmission efficiency can be ensured well, and the increase in the pressing force can be prevented.

Drawings

Fig. 1 is a cross-sectional view schematically showing a friction roller speed reducer according to a first example of the first embodiment.

Fig. 2 is a partially cut-away perspective view showing a sun roller, a pair of roller elements constituting a ring roller, an intermediate roller, and an elastic member, extracted from a friction roller speed reducer of a first example of the first embodiment.

Fig. 3 is a cross-sectional view schematically showing a sun roller, a pair of roller elements constituting a ring roller, an intermediate roller, and an elastic member, taken from a friction roller speed reducer of a first example of the first embodiment.

Fig. 4 is a graph showing the relationship between slip and traction coefficient in the transmission direction of torque and in the direction perpendicular to the transmission direction of torque when the skew occurs.

Fig. 5 is an enlarged cross-sectional view of a main part for explaining the effect of the friction roller reducer of the first example of the first embodiment.

Fig. 6 (a) to 6 (C) are diagrams showing three examples of the shape of the rolling surface.

Fig. 7 (a) to 7 (C) are enlarged cross-sectional views of main parts of the second to fourth examples of the first embodiment.

Fig. 8 is an enlarged cross-sectional view showing a main portion of a friction roller speed reducer of a fifth example of the first embodiment.

Fig. 9 is an enlarged cross-sectional view showing a main portion of a friction roller speed reducer of a sixth example of the first embodiment.

Fig. 10 (a) and 10 (B) are enlarged cross-sectional views of main parts showing a seventh example and an eighth example of the first embodiment.

Fig. 11 is an enlarged cross-sectional view showing a main portion of a friction roller speed reducer of a ninth example of the first embodiment.

Fig. 12 is a cross-sectional view schematically showing a friction roller reducer according to a first example of the second embodiment.

Fig. 13 is a cross-sectional view schematically showing a main part of a friction roller speed reducer according to a first example of the second embodiment.

Fig. 14 is a cross-sectional view schematically showing a main part of a friction roller speed reducer of a second example of the second embodiment.

Fig. 15 is a cross-sectional view schematically showing a friction roller reducer according to a first example of the third embodiment.

Fig. 16 is a partially cut-away perspective view showing a sun roller, a pair of roller elements constituting a ring roller, an intermediate roller, and an elastic member extracted from a friction roller speed reducer of the first example of the third embodiment.

Fig. 17 is an enlarged view of the X portion of fig. 15.

Fig. 18 is a cross-sectional view schematically showing a friction roller reducer according to a first example of the fourth embodiment.

Fig. 19 is a sectional view of the elastic member extracted and shown in a free state.

Fig. 20 is a graph showing the relationship between the deflection δ of the belleville spring and the spring load P.

FIG. 21 is a graph showing torque and spring load P, operating traction coefficient μ, limit traction coefficient μ transmitted by a friction roller reducer _max And a graph of the relationship of the pressing force F of the loading cam device.

Fig. 22 is a cross-sectional view showing a friction roller reducer according to a first example of the fifth embodiment.

Fig. 23 is a partially cut-away perspective view showing a sun roller, a pair of roller elements constituting a ring roller, an intermediate roller, and an elastic member extracted from a friction roller speed reducer of a first example of the fifth embodiment.

Fig. 24 is a perspective view showing one of a pair of belleville springs constituting an elastic member in an extracted manner in the first example of the fifth embodiment.

Fig. 25 is an enlarged cross-sectional view showing a main portion of a friction roller speed reducer of a second example of the fifth embodiment.

Fig. 26 is a perspective view showing one of a pair of belleville springs constituting an elastic member in an extracted manner in a second example of the fifth embodiment.

Fig. 27 is an enlarged cross-sectional view showing a main part of a friction roller speed reducer of a third example of the fifth embodiment.

Fig. 28 is a perspective view showing a belleville spring constituting an elastic member in an extracted manner in a third example of the fifth embodiment.

Fig. 29 is an enlarged cross-sectional view showing a main portion of a friction roller speed reducer of a fourth example of the fifth embodiment.

Fig. 30 is a perspective view showing a pad in an extracted manner in a fourth example of the fifth embodiment.

Fig. 31 is an enlarged cross-sectional view showing a main portion of a friction roller speed reducer of a fifth example of the fifth embodiment.

Fig. 32 is a perspective view showing a tooth lock washer in an extracted manner in a fifth example of the fifth embodiment.

Fig. 33 is an enlarged cross-sectional view showing a main portion of a friction roller speed reducer of a sixth example of the fifth embodiment.

Fig. 34 is an enlarged cross-sectional view showing a main portion of a friction roller speed reducer of a seventh example of the fifth embodiment.

Fig. 35 is a perspective view showing one roller element in an extracted manner in a seventh example of the fifth embodiment.

Fig. 36 is a perspective view showing one of a pair of belleville springs constituting an elastic member in an extracted manner in an eighth example of the fifth embodiment.

Fig. 37 is a cross-sectional view schematically showing a friction roller reducer according to a first example of the sixth embodiment.

Fig. 38 is a partially cut-away perspective view showing a sun roller, a pair of roller elements constituting a ring roller, an intermediate roller, and an elastic member extracted from a friction roller speed reducer of the first example of the sixth embodiment.

Fig. 39 is an enlarged view of the Y portion of fig. 38.

Fig. 40 is a side view of a friction roller reducer according to a first example of the sixth embodiment as viewed from the radially outer side.

Fig. 41 is an enlarged view of the Z portion of fig. 40.

Fig. 42 is a perspective view showing a friction roller reducer according to a first example of the sixth embodiment.

Fig. 43 is an enlarged cross-sectional view of a main part showing an example of a configuration in which a gap is provided between a roller element and an elastic member.

Fig. 44 is a graph showing a relationship between the transmission torque of the friction roller reducer and the thrust force of the loading cam device and the reaction force (elastic restoring force) of the elastic member.

Fig. 45 is an enlarged cross-sectional view showing a main part of a second example of the sixth embodiment.

Fig. 46 is an enlarged cross-sectional view showing a main part of a third example of the sixth embodiment.

Fig. 47 is an enlarged cross-sectional view showing a main part of a fourth example of the sixth embodiment.

Fig. 48 is an enlarged cross-sectional view showing a main part of a fifth example of the sixth embodiment.

Fig. 49 is an enlarged cross-sectional view showing a main part of a sixth example of the sixth embodiment.

Fig. 50 is an enlarged cross-sectional view showing a main part of a seventh example of the sixth embodiment.

Fig. 51 is an enlarged cross-sectional view showing a main part of an eighth example of the sixth embodiment.

Fig. 52 is a view corresponding to fig. 41 showing a ninth example of the sixth embodiment.

Fig. 53 is a cross-sectional view schematically showing a friction roller reducer according to a first example of the seventh embodiment.

Fig. 54 is a cross-sectional perspective view showing an example of a conventional structure of a friction roller reducer.

Fig. 55 is a graph showing the relationship between the surface pressure of the traction portion and the maximum limit traction coefficient.

Detailed Description

[ first example of the first embodiment ]

Fig. 1 to 6 (C) show a first example of the first embodiment of the present invention. The friction roller reducer 1 of the present example increases the torque of the input shaft 2, and outputs the torque to the output shaft 3. The friction roller reducer 1 includes an input shaft 2, an output shaft 3, a sun roller 4, a ring roller 5, a plurality of intermediate rollers 6, a loading cam device 7, and an elastic member 8.

In the following description, unless otherwise specified, the axial direction, the radial direction, and the circumferential direction refer to the axial direction, the circumferential direction, and the radial direction of the input shaft 2. The axial direction, radial direction, and circumferential direction of the input shaft 2 coincide with the axial direction, radial direction, and circumferential direction of the output shaft 3, the sun roller 4, and the ring roller 5.

The input shaft 2 has an external spline portion 9 at one axial end (a base end, a left end in fig. 2). The male spline section 9 is spline-engaged with a female spline section provided on an output shaft of a drive source such as an electric motor or an engine. That is, the input shaft 2 is driven to rotate by the driving source.

The output shaft 3 is supported coaxially with the input shaft 2 and is relatively rotatable with respect to the input shaft 2. The output shaft 3 has a flange portion 10 protruding radially outward at one axial end (front end, left end in fig. 1).

The sun roller 4 has an inner diameter side rolling contact surface 11 on the outer peripheral surface. In this example, the inner diameter side rolling contact surface 11 is constituted by a cylindrical surface whose outer diameter does not change in the axial direction. The sun roller 4 is provided integrally with the input shaft 2 at the other axial end (front end, right end in fig. 1 and 2) of the input shaft 2. However, the sun roller and the input shaft may be configured separately, and the sun roller and the input shaft may be coupled and fixed coaxially with each other.

The ring roller 5 has an outer diameter rolling contact surface 12 on the inner peripheral surface, and is disposed coaxially with the sun roller 4 around the sun roller 4. The ring roller 5 includes a pair of roller elements 13a, 13b and a coupling cylinder 14.

The pair of roller elements 13a, 13b have inclined surface portions 15a, 15b on the inner peripheral surface, which are inclined in the radial direction in the direction approaching the intermediate roller 6, that is, in the direction in which the inner diameter becomes smaller as they are separated from each other in the axial direction. That is, in this example, the outer diameter side rolling contact surface 12 is constituted by inclined surface portions 15a, 15b of the pair of roller elements 13a, 13 b. In this example, the inclined surface portions 15a and 15b are formed of conical concave surfaces having a linear busbar shape (cross-sectional shape).

The pair of roller elements 13a and 13b have flat surface portions 16 orthogonal to the respective center axes O on the end surfaces facing each other, that is, the end surface on the other side in the axial direction of the roller element 13a on one side in the axial direction and the end surface on the one side in the axial direction of the roller element 13b on the other side in the axial direction. In this example, the entire front end surfaces of the pair of roller elements 13a, 13b are constituted by the flat surface portion 16. The pair of roller elements 13a and 13b has element-side engaging concave-convex portions 17 in which concave portions and convex portions are alternately arranged over the entire circumference on the outer peripheral surface of the portion on the side that is axially adjacent to each other.

The coupling tube 14 includes a cylindrical portion 18 and a side plate portion 19 bent radially inward from one axial end of the cylindrical portion 18. The cylindrical portion 18 has a cylindrical-side engaging concave-convex portion 20 in which concave portions and convex portions are alternately arranged over the entire circumference on an inner circumferential surface ranging from one end portion to the intermediate portion in the axial direction.

The ring roller 5 of the present example combines the pair of roller elements 13a, 13b by the coupling cylinder 14 so as to be axially relatively displaceable and not relatively rotatable. Specifically, of the pair of roller elements 13a, 13b, the roller element 13a on one axial side is prevented from being displaced to one axial side by engaging the element-side engaging concave-convex portion 17 with the one axial side portion of the tube-side engaging concave-convex portion 20 of the connecting tube 14 and by abutting the end surface on one axial side against the side surface on the other axial side of the side plate portion 19 of the connecting tube 14. In contrast, the roller element 13b on the other axial side engages the element-side engaging concave-convex portion 17 with an axially intermediate portion of the tube-side engaging concave-convex portion 20 of the connecting tube 14 so as to be axially displaceable. Accordingly, the pair of roller elements 13a, 13b and the coupling cylinder 14 integrally rotate.

The plurality of intermediate rollers 6 have rolling surfaces 21 on the outer peripheral surface that are in rolling contact with the inner diameter side rolling contact surface 11 of the sun roller 4 and the outer diameter side rolling contact surface 12 of the ring roller 5. The rolling surface 21 has: a pair of intermediate roll inclined portions 22 which are disposed at both axial side portions and which are inclined in a direction in which the outer diameter decreases as the axial direction moves toward the direction of separation from each other; and a connecting surface portion 23 disposed at the axial intermediate portion and connecting the pair of intermediate roll side inclined portions 22 to each other. In this example, the pair of intermediate roll inclined portions 22 is constituted by a convex curved surface having a circular arc-shaped busbar shape (cross-sectional shape). The connecting surface portion 23 is formed of a cylindrical surface whose outer diameter does not change in the axial direction. The inner diameter side rolling contact surface 11 of the sun roller 4 is in rolling contact with the connecting surface portion 23 of the rolling surface 21, and the inclined surface portions 15a, 15b constituting the outer diameter side rolling contact surface 12 of the ring roller 5 are in rolling contact with the intermediate roller side rolling contact portion 22 of the rolling surface 21, respectively.

The intermediate roller 6 is supported so as to be rotatable (autorotative) about a rotation shaft 24 provided in a central portion and displaceable in a radial direction with respect to a support member that does not rotate even when the housing or the like is in use. That is, the intermediate rollers 6 are each rotatable, but are prevented from rotating (revolving) about the central axis O of the input shaft 2.

The structure for supporting the intermediate roller 6 with respect to the support member so as to be capable of rotation and displacement in the radial direction is not particularly limited, and various conventionally known structures can be employed. Specifically, for example, the rotation shaft 24 of the intermediate roller 6 is rotatably supported by the bracket 25 via the radial rolling bearing 26, and the bracket 25 is supported by the support member so as to be capable of swinging about a swinging shaft located at a portion offset from the central axis of the radial rolling bearing 26 in the circumferential direction.

The loading cam device 7 presses the pair of roller elements 13a, 13b in a direction to bring the pair of roller elements 13a, 13b closer to each other. That is, in the friction roller speed reducer 1 of the present example, the loading cam device 7 constitutes a pressing device. The loading cam device 7 includes a roller element 13b on the other axial side, a cam plate 27, and a plurality of rolling elements 28.

The roller element 13b on the other side in the axial direction has driving-side cam surfaces 29 on the other side in the axial direction, each of which has the same number of concave portions and convex portions, alternately arranged in the circumferential direction.

The cam plate 27 includes a cylindrical portion 30 and a side plate portion 31 bent outward in the radial direction from one axial end of the cylindrical portion 30. The side plate 31 has driven side cam surfaces 32 formed by alternately arranging the same number of concave portions and convex portions in the circumferential direction on one side surface in the axial direction.

The cam plate 27 is supported inside the axial other side portion of the cylindrical portion 18 of the coupling cylinder 14 so as to be relatively rotatable with respect to the coupling cylinder 14 and not displaceable to the axial other side with respect to the coupling cylinder 14. For this purpose, a thrust needle bearing 33, a thrust race 34, and a retainer 35 are disposed between the cam plate 27 and the cylindrical portion 18 of the connecting tube 14. The thrust race 34 is prevented from being displaced toward the axial direction other side by a retainer 35 engaged with the axial direction other side end portion of the cylindrical portion 18. The thrust needle bearing 33 is disposed between the other axial side surface of the cam plate 27 and one axial side surface of the thrust race 34.

The cam plate 27 couples the cylindrical portion 30 so as to be axially displaceable relative to the flange portion 10 of the output shaft 3 and so as not to be rotatable relative thereto. Thus, the output shaft 3 and the cam plate 27 integrally rotate. Specifically, for example, by spline-engaging the female spline portion provided on the inner peripheral surface of the cylindrical portion 30 with the male spline portion provided on the outer peripheral surface of the flange portion 10, the cam plate 27 and the output shaft 3 can be combined so as to be relatively displaceable in the axial direction and not relatively rotatable.

The plurality of rolling elements 28 are disposed between the driving-side cam surface 29 of the roller element 13b on the other side in the axial direction and the driven-side cam surface 32 of the cam plate 27 so as to be capable of rolling.

The elastic member 8 is formed in an annular shape and is disposed between the flat surface portions 16 of the pair of roller elements 13a and 13b. In this example, the elastic member 8 is formed by combining a pair of belleville springs 36 having a truncated cone shape so that the inner diameter side thereof is opened, and the cross section thereof is substantially V-shaped. Specifically, in this example, the pair of belleville springs 36 are overlapped in opposite axial directions so that the large diameter side end portions are abutted against each other. That is, the elastic member 8 is configured by combining two layers of the pair of belleville springs 36 in series.

When the elastic member 8 is elastically compressed between the flat surface portions 16 of the pair of roller elements 13a and 13b, the pair of roller elements 13a and 13b are elastically urged in a direction to axially separate the pair of roller elements 13a and 13b from each other (force in a direction to separate the pair of roller elements 13a and 13b from each other) in order to be elastically restored. In other words, the elastic member 8 presses the pair of roller elements 13a, 13b in a direction away from the rolling surface 21 of the intermediate roller 6 in the axial direction.

In this example, in the initial state before the pressing force is exerted by the loading cam device 7, the elastic member 8 is sandwiched between the flat surface portions 16 of the pair of roller elements 13a and 13b in a state of being elastically compressed. Therefore, the elastic member 8 applies a force in a direction of separating the pair of roller elements 13a and 13b from each other even in the initial state.

In the operation of the friction roller reducer 1 of the present example, the input shaft 2 is driven to rotate by a drive source such as an electric motor or an engine, so that the sun roller 4 is driven to rotate. When the sun roller 4 rotates, the intermediate roller 6 rotates based on the rolling contact between the inner diameter side rolling contact surface 11 of the sun roller 4 and the connecting surface portion 23 of the rolling surface 21 of the intermediate roller 6. When the intermediate roller 6 rotates, the ring roller 5 rotates about the central axis O of the input shaft 2 due to the rolling contact between the pair of intermediate roller-side inclined portions 22 in the rolling surface 21 of the intermediate roller 6 and the pair of inclined surface portions 15a, 15b constituting the outer diameter-side rolling contact surface 12 of the ring roller 5. The rotation of the ring roller 5 is transmitted to the output shaft 3 via the loading cam device 7.

When the roller element 13b on the other side rotates in the axial direction with the rotation of the ring roller 5, the amount of jump from the bottom of the concave portion of the driving side cam surface 29 and the amount of jump from the bottom of the concave portion of the driven side cam surface 32 of the rolling element 28 of the loading cam device 7 increase. Thereby, the axial dimension of the loading cam device 7 increases, the pair of roller elements 13a, 13b are pressed in the directions approaching each other, and the cam plate 27 is driven to rotate. That is, the roller element 13b on the other side in the axial direction is pressed to the one side in the axial direction, and at the same time, the cam plate 27 is pressed to the other side in the axial direction, whereby the roller element 13a on the one side in the axial direction is pulled toward the other side in the axial direction via the connecting tube 14.

When the pair of roller elements 13a, 13b are pressed in the directions approaching each other, the inner diameter of the portion of the inclined surface portions 15a, 15b constituting the outer diameter side rolling contact surface 12 that is in rolling contact with the pair of intermediate roller side rolling portions 22 constituting the rolling surface 21 becomes smaller, and the surface pressure of the traction portion (rolling contact portion) between the outer diameter side rolling contact surface 12 and the rolling surface 21 increases. When the intermediate rollers 6 are pressed inward in the radial direction along with the surface pressure rise, the surface pressure of the traction portion between the connecting surface portion 23 of the rolling surface 21 and the inner diameter side rolling contact surface 11 also rises. As a result, excessive slip does not occur in each traction portion, and the torque input from the input shaft 2 to the sun roller 4 is transmitted to the ring roller 5 via the intermediate roller 6.

The rotation of the cam plate 27 is transmitted from the fitting portion of the cylindrical portion 30 and the flange portion 10 to the output shaft 3, and is transmitted to a driven portion such as a wheel via a propeller shaft or the like.

In the friction roller reducer 1 of the present example, the elastic member 8 is sandwiched between the flat surface portions 16 of the pair of roller elements 13a and 13b, and the elastic member 8 applies a force in a direction of separating the pair of roller elements 13a and 13b from each other. Therefore, the amount of increase in the surface pressure of the traction portion between the rolling surface 21 and the inner-diameter-side rolling contact surface 11 and the outer-diameter-side rolling contact surface 12, which is formed by pressing the pair of roller elements 13a, 13b in the direction in which the pair of roller elements 13a, 13b approach each other, due to the loading cam device 7, becomes smaller by the amount corresponding to the force in the direction in which the pair of roller elements 13a, 13b are separated from each other, which is applied from the elastic member 8. In other words, the magnitude of the normal force acting on each traction portion is reduced by the amount corresponding to the force applied from the elastic member 8 to the pair of roller elements 13a and 13b, and the operation traction coefficient (tangential force/normal force corresponding to the torque transmitted from the sun roller 4, the ring roller 5, and the intermediate roller 6) indicating the actual operation state is increased.

Here, the larger the torque transmitted by the friction roller reducer 1, the larger the torque applied to the ring roller 5, the larger the relative displacement amount of the pair of roller elements 13a, 13b in the direction approaching each other, and the larger the compression amount of the elastic member 8. Therefore, the larger the torque applied to the ring roller 5, the larger the force in the direction of separating the pair of roller elements 13a, 13b from the elastic member 8.

Therefore, torque transmitted to the friction roller reducer 1, that is, tangential force and surface pressure acting on the traction portion are small, and the maximum limit traction coefficient μ is small _max In a small region, the force applied from the elastic member 8 to the pair of roller elements 13a and 13b in the direction of separation from each other is suppressed to be small, and the running drag coefficient can be suppressed to be small. On the other hand, torque transmitted to the friction roller reducer 1, that is, tangential force and surface pressure acting on the traction portion are large, and the maximum limit traction coefficient μ is large _max In a large area, the force applied from the elastic member 8 to the pair of roller elements 13a and 13b in the direction of separation from each other increases, and accordingly, the magnitude of the normal force acting on the traction portion decreases, so that the running traction coefficient can be suppressed to be large. In short, according to the friction roller reducer 1 of the present embodiment, the running traction coefficient can be adjusted to an appropriate level regardless of the magnitude of the transmitted torque, and the transmission efficiency of the friction roller reducer 1 can be ensured well.

In the friction roller reducer 1 of the present example, the pressing means for pressing the pair of roller elements 13a, 13b in a direction away from the rolling surface 21 of the intermediate roller 6 is constituted by the loading cam means 7. That is, as described above, the structure is realized in which the running traction coefficient can be adjusted to an appropriate level without providing a driver such as a hydraulic pump or an electric motor. Therefore, the friction roller reducer 1 can be prevented from being enlarged and complicated.

When the intermediate roller 6 rotates with the rotation shaft 24 of the intermediate roller 6 inclined with respect to the central axis O of the input shaft 2, as shown in fig. 4, the larger the traction coefficient (=tangential force/normal force) in the torque transmission direction, the smaller the traction coefficient (=skew force/normal force) in the direction perpendicular to the torque transmission direction.

In the friction roller reducer 1 of the present example, since the normal force acting on the traction portion can be suppressed to be small and the traction coefficient in the torque transmission direction can be increased based on the case where the elastic member 8 is to be elastically restored, the traction coefficient in the direction perpendicular to the torque transmission direction can be relatively suppressed to be small. In particular, in the friction roller reducer 1 of the present example, the running drag coefficient can be increased in the high torque transmission in which the elastic deformation amount of each member and the posture change of the intermediate roller 6 are liable to become large, and the acceleration increase of the pressing force of the loading cam device 7 due to the occurrence of the deflection of the intermediate roller 6 can be effectively prevented.

In the friction roller reducer 1 of the present example, when either one of the pair of roller elements 13a, 13b (13 b) is displaced toward one side of the other roller element 13b (13 a) due to the occurrence of the deflection, and the pressing force of the inclined surface portion 15a (15 b) of the one roller element 13a (13 b) against the intermediate roller-side inclined surface portion 22 increases, the other roller element 13b (13 a) is pressed by the one roller element 13a (13 b) via the elastic member 8 in a direction away from the one roller element 13a (13 b). As a result, the pressing force of the inclined surface portion 15b (15 a) of the other roller element 13b (13 a) against the intermediate roller-side inclined portion 22 is reduced. As a result, the torque transmitted at the traction portion between the inclined surface portion 15a (15 b) of the one roller element 13a (13 b) and the intermediate roller-side inclined portion 22 is larger than the torque transmitted at the traction portion between the inclined surface portion 15b (15 a) of the other roller element 13b (13 a) and the intermediate roller-side inclined portion 22. Therefore, the traction coefficient in the transmission direction of the torque at the traction portion between the inclined surface portion 15a (15 b) of the one roller element 13a (13 b) and the intermediate roller-side inclined surface portion 22 can be increased, and the traction coefficient in the direction perpendicular to the transmission direction of the torque can be suppressed relatively small. From this, it is also clear that the acceleration of the pressing force due to the occurrence of the deflection of the intermediate roller 6 can be effectively prevented from increasing.

In the friction roller reducer 1 of the present example, the rolling surface 21 is constituted by a pair of intermediate roller-side rolling portions 22 disposed at both axial side portions and in rolling contact with the inclined surface portions 15a, 15b constituting the outer-diameter-side rolling contact surface 12, and a connecting surface portion 23 disposed at the axial intermediate portion and in rolling contact with the inner-diameter-side rolling contact surface 11. Therefore, the magnitude of the force applied to the pair of roller elements 13a, 13b by the elastic member 8 can be easily adjusted while maintaining the torque transmission efficiency of the friction roller reducer 1 satisfactorily. The reason for this will be described with reference to fig. 5.

The force applied by the elastic member 8 to the pair of roller elements 13a, 13b, that is, the adjustment of the magnitude of the elastic force of the elastic member 8 can be performed by adjusting the distance d between the flat surface portions 16 of the pair of roller elements 13a, 13b ₁ To do so. Here, when the interval d is desired to be increased ₁ In the case of (a), the axial distance d between the contact points P between the inclined surface portions 15a, 15b of the pair of roller elements 13a, 13b and the rolling surface 21 of the intermediate roller 6 ₂ Also an increase is required.

In the structure in which the rolling surface 21z of the intermediate roller 6z is formed of a convex curved surface having a single circular arc shape as in the comparative example shown in fig. 5 (B), it is desirable to increase the axial distance d between the contact points P between the inclined surface portions 15a, 15B and the rolling surface 21z ₂ In the case of (B) of fig. 5, it is necessary to increase the radius of curvature of the generatrix of the rolling surface 21z as shown in (B) of fig. 5. However, if the radius of curvature of the generatrix of the rolling surface 21z is increased, the area of the contact ellipse existing at the rolling contact portion between the inclined surface portions 15a, 15b and the rolling surface 21z becomes large, and the loss due to the sliding at the rolling contact portion increases, and there is a possibility that the torque transmission efficiency is reduced.

In contrast, in the friction roller reducer 1 of the present example, by increasing the axial dimension L of the connecting surface portion 23 of the rolling surface 21 as shown in fig. 5 (a) →5 (a) (b), the axial distance d between the contact points P between the rolling surface 21 (intermediate roller-side inclined surface portion 22) and the inclined surface portions 15a, 15b can be increased while the curvature radius of the generatrix of the intermediate roller-side inclined surface portion 22 in rolling contact with the inclined surface portions 15a, 15b remains unchanged ₂ . That is, even when the axial distance d is increased in order to adjust the force applied by the elastic member 8 to the pair of roller elements 13a, 13b ₂ In the case of (2), contact at the rolling contact portion between the inclined surface portions 15a, 15b and the rolling surface 21 can be preventedThe elliptical area becomes large, and a decrease in torque transmission efficiency of the friction roller reducer 1 can be prevented.

In this example, as shown in fig. 6 (a), the rolling surface 21 includes a pair of intermediate roll side inclined portions 22 having a circular arc bus shape, and a connecting surface portion 23 which is a cylindrical surface whose outer diameter does not change in the axial direction. However, as shown in fig. 6 (B), the rolling surface 21a may be constituted by a pair of intermediate roll side inclined portions 22 having a circular arc bus bar shape and a connecting surface portion 23a having a circular arc bus bar shape. In this case, the radius of curvature of the generatrix connecting the face portions 23a is larger than the radius of curvature of the generatrix of the intermediate roll side inclined portion 22. Alternatively, as shown in fig. 6 (C), the rolling surface 21b may be constituted by a pair of intermediate roll inclined portions 22a having a linear busbar shape inclined in a direction in which the outer diameter becomes smaller as they are separated from each other in the axial direction, and a connecting surface portion 23 which is a cylindrical surface in which the outer diameter does not change in the axial direction.

However, in the case of carrying out the present invention, the rolling surface of the intermediate roller may be formed of a convex curved surface having a circular arc shape of a bus bar. In this case, the inner diameter side rolling contact surface provided on the outer peripheral surface of the sun roller may be configured as a concave curved surface having a circular arc bus shape.

In this example, the elastic member 8 disposed between the pair of roller elements 13a and 13b is constituted by the pair of belleville springs 36, but in the case of carrying out the present invention, the elastic member may apply a force in a direction of separating the pair of roller elements from each other along with compression, and may be constituted by various elastic members without being limited to belleville springs. The force exerted by the elastic member in association with compression may or may not be proportional to the amount of compression. The elastic member preferably generates a force such that the operating traction coefficient exceeds the maximum limit traction coefficient and becomes as close to the maximum limit traction coefficient as possible.

Second to fourth examples of the first embodiment

In the case of implementing the present invention, in the case of forming the elastic member by the belleville springs, the number of belleville springs and/or the combination method and the like are appropriately determined according to the magnitude of the elastic force required by the elastic member. However, in the case where the elastic member is constituted by a belleville spring, it is preferable to suppress the number of belleville springs as small as possible in order to suppress the influence of hysteresis of the spring characteristics to be small.

In the second example of the first embodiment shown in fig. 7 (a), the elastic member 8a is constituted by a single belleville spring 36.

In the third example of the first embodiment shown in fig. 7 (B), the elastic member 8B is configured by overlapping two belleville springs 36 of the three belleville springs 36 in the same direction and overlapping the remaining belleville springs 36 in opposite directions.

In the fourth example of the first embodiment shown in fig. 7 (C), the elastic member 8C is configured by combining two belleville springs 36 of the four belleville springs 36 in the same direction and overlapping them in opposite directions, that is, by combining two belleville springs in parallel and two layers in series.

[ fifth example of the first embodiment ]

Fig. 8 shows a fifth example of the first embodiment of the present invention. In this example, the elastic member 8d disposed on the front end surfaces (flat surface portions 16) of the pair of roller elements 13a and 13b constituting the ring roller 5 is constituted by a wave washer. The other parts are similar in structure and operation to those of the first example of the first embodiment.

[ sixth example of the first embodiment ]

Fig. 9 shows a sixth example of the first embodiment of the present invention. In this example, the elastic member 8e disposed between the front end surfaces (flat surface portions 16) of the pair of roller elements 13a and 13b constituting the ring roller 5 is constituted by a torsion coil spring 37. The torsion coil springs 37 may be disposed one between the front end surfaces of the pair of roller elements 13a and 13b, or may be provided in plural locations at equal intervals in the circumferential direction between the front end surfaces of the pair of roller elements 13a and 13 b. In the case of providing the torsion coil springs 37, for example, the torsion coil springs can be disposed at a plurality of positions in the circumferential direction between the distal end surfaces of the pair of roller elements 13a and 13b, that is, can be disposed in parallel. And/or, the plurality of torsion coil springs 37 can be arranged to overlap in the axial direction, that is, arranged in series.

In any case, the torsion coil springs 37 are disposed between the front end surfaces of the pair of roller elements 13a and 13b so that the central axis is parallel to the central axis of the ring roller 5. Thereby, the elastic restoring force of the torsion coil spring 37 acts on the roller elements 13a, 13b in the axial direction. The other parts are similar in structure and operation to those of the first example of the first embodiment.

Seventh and eighth examples of the first embodiment

Fig. 10 (a) shows a seventh example of the first embodiment of the present invention. The elastic member 8f of this example includes a plurality of torsion coil springs 37. In this example, a plurality of holding concave portions 38 recessed in the axial direction are provided at a plurality of circumferentially equally spaced portions of the opposed front end surfaces of the pair of roller elements 13c, 13d constituting the ring roller 5 a. The torsion coil springs 37 are inserted into the holding concave portions 38 at the axial both ends thereof.

According to this example, even when friction acting between the axial end surface of the torsion coil spring 37 and the front end surfaces of the roller elements 13c, 13d becomes small, the setting position deviation of the torsion coil spring 37 can be prevented. The configuration and the operational effects of the other parts are the same as those of the first example and the third example of the first embodiment.

Fig. 10 (B) shows an eighth example of the first embodiment of the present invention. The elastic member 8g of this example includes a plurality of torsion coil springs 37. The friction roller reducer 1 of the present example has a holder 39 for holding a plurality of torsion coil springs 37. The retainer 39 has a hollow circular plate shape, and has retaining holes 40 penetrating in the axial direction at a plurality of positions equally spaced in the circumferential direction. Each torsion coil spring 37 is inserted through the axial intermediate portion inside the holding hole 40.

In this example, even when friction acting between the axial end surface of the torsion coil spring 37 and the front end surfaces of the roller elements 13a, 13b is small, the installation position of the torsion coil spring 37 can be prevented from being shifted. Further, the position of the elastic member 8g in the radial direction can be easily adjusted by merely replacing the retainer 39. The configuration and the operational effects of the other parts are the same as those of the first example and the third example of the first embodiment.

Ninth example of the first embodiment

Fig. 11 shows a ninth example of the first embodiment of the present invention. In this example, in an initial state before the pressing force is exerted by the loading cam device 7 (see fig. 1), a gap 41 is provided between the elastic member 8h and the roller element 13b on the other side in the axial direction of the pair of roller elements 13a, 13b constituting the ring roller 5.

In this example, in the initial state, since the gap 41 is provided between the elastic member 8h and the roller element 13b on the other axial side, the pair of roller elements 13a and 13b are not acted on the force in the direction of separation due to the elastic restoration of the elastic member 8h in the region where the torque transmitted by the friction roller reducer 1 is small. Therefore, in a low torque region where the torque transmitted by the friction roller reducer 1 is small and the surface pressure of the traction portion is small, the traction coefficient can be prevented from becoming excessively small, and the occurrence of extreme slip can be prevented more reliably. The other parts are similar in structure and operation to those of the first example of the first embodiment.

[ first example of the second embodiment ]

Fig. 12 and 13 show a first example of the second embodiment of the present invention. In the friction roller reducer 1a of the present example, the ring roller 5b is configured by combining the pair of roller elements 13a, 13b by the coupling cylinder 14a so as to be capable of relative displacement in the axial direction and not capable of relative rotation. The coupling tube 14a includes a cylindrical portion 18a and a side plate portion 19 bent radially inward from one axial end of the cylindrical portion 18 a. In this example, the cylindrical portion 18a has an opening 42 penetrating in the radial direction at one to a plurality of positions in the circumferential direction of the portion of the elastic member 8 located radially outward. In this example, the opening 42 is located at a portion between the flat faces 16 of the pair of roller elements 13a, 13b in the axial direction. The opening 42 constitutes an oil drain hole for draining the lubricating oil present in the space radially inside the cylindrical portion 18a to the space radially outside the cylindrical portion 18 a.

In the friction roller reducer 1a of the present example, a support member (bracket) 43 that supports each intermediate roller 6 so as to be rotatable about the rotation shaft 24 and displaceable in the radial direction has oil feed holes 44 at a plurality of circumferential positions of portions of the pair of roller elements 13a, 13b that face the inclined surface portions 15a, 15 b. During operation of the friction roller reducer 1a, lubricating oil (traction oil) is discharged from each of the oil supply holes 44. The lubricating oil discharged from each oil supply hole 44 is supplied to a traction portion between the rolling surface 21 of the intermediate roller 6 and the inner diameter side rolling contact surface 11 of the sun roller 4 and/or the outer diameter side rolling contact surface 12 of the ring roller 5. Thereby, cooling is performed while lubricating the traction portion.

Like the elastic member 8 of the friction roller reducer 1 of the first example of the first embodiment, the elastic member 8 is formed by combining a pair of belleville springs 36 having a truncated cone shape so as to have an opening on the inner diameter side and have a substantially V-shaped cross section. Specifically, the pair of belleville springs 36 are overlapped in opposite axial directions so that the large diameter side end portions are abutted against each other. That is, the elastic member 8 is configured by combining two layers of the pair of belleville springs 36 in series.

In the friction roller reducer 1 of the present example, the elastic member 8 is formed by combining a pair of belleville springs 36 so as to have an opening on the inner diameter side and have a substantially V-shaped cross section. Therefore, even when the elastic force exerted by the elastic member 8 is 0 or less, the posture of the elastic member 8 can be stabilized, and abrasion and abnormal noise can be prevented from occurring between the elastic member 8 and the pair of roller elements 13a and 13 b.

That is, the lubricating oil discharged from the oil supply hole 44 provided in the support member 43 is supplied to the traction portion between the inclined surface portions 15a, 15b of the pair of roller elements 13a, 13b constituting the ring roller 5 and the rolling surface 21 of the intermediate roller 6. When the pair of roller elements 13a and 13b rotate, the lubricating oil positively flows toward the large diameter side end portions of the inclined surface portions 15a and 15b of the pair of roller elements 13a and 13b due to centrifugal force, and is fed between the pair of belleville springs 36. Thus, the pair of belleville springs 36 are expanded so as to expand the axial dimension, and the small diameter side end portions of the pair of belleville springs 36 are pressed against the front end surfaces (flat surface portions 16) of the pair of roller elements 13a, 13 b.

Therefore, in order to reduce the torque transmitted by the friction roller reducer 1a and the change in the axial dimension of the loading cam device 7, the elastic member 8 is not elastically deformed or the elastic deformation amount of the elastic member 8 is small, and the force of pressing the small diameter side end portions of the pair of belleville springs 36 against the distal end surfaces of the pair of roller elements 13a, 13b based on the elastic force of the elastic member 8 is small, even in such a case, the small diameter side end portions of the pair of belleville springs 36 can be pressed against the distal end surfaces of the pair of roller elements 13a, 13 b. This stabilizes the posture of the elastic member 8, and prevents wear and abnormal noise from occurring between the pair of belleville springs 36 and the pair of roller elements 13a and 13 b.

The lubricating oil fed between the pair of belleville springs 36 leaks or seeps radially outward from the abutting portions of the large-diameter side ends of the pair of belleville springs 36, and is discharged through the opening 42 provided in the connecting tube 14 a. The other parts are similar in structure and operation to those of the first example of the first embodiment.

[ second example of the second embodiment ]

Fig. 14 shows a second example of the second embodiment of the present invention. This example is a modification of the first example of the second embodiment. In this example, the oil supply hole 44 for discharging the lubricating oil provided in the support member 43 is provided not only at the portion facing the inclined surface portions 15a, 15b of the pair of roller elements 13a, 13b constituting the ring roller 5, but also at the portion facing the space where the elastic member 8 is arranged between the front end surfaces (flat surface portions 16) of the pair of roller elements 13a, 13 b.

According to this example, the lubricating oil can be directly fed between the pair of belleville springs 36 by the oil feed hole 44 provided in the portion facing the space where the elastic member 8 is disposed, of the oil feed holes 44 provided in the support member 43. Therefore, immediately after the start of the operation of the friction roller reducer 1, the small diameter side end portions of the pair of belleville springs 36 can be pressed against the front end surfaces of the pair of roller elements 13a, 13 b. The configuration and the operational effects of the other parts are the same as those of the first example and the fifth example of the first embodiment.

[ first example of the third embodiment ]

Fig. 15 to 17 show a first example of a third embodiment of the present invention. In the friction roller reducer 1b of the present example, the ring roller 5c is configured by combining the pair of roller elements 13a, 13b by the coupling cylinder 14b so as to be capable of relative displacement in the axial direction and not capable of relative rotation.

The coupling tube 14b has a cylindrical portion 18b and a side plate portion 19a bent radially inward from the other end portion of the cylindrical portion 18b in the axial direction. The cylindrical portion 18b has a cylindrical-side engaging concave-convex portion 20 in which concave portions and convex portions are alternately arranged over the entire circumference on the inner circumferential surface ranging from one end portion to the intermediate portion in the axial direction.

In this example, the element-side engagement concave-convex portion 17 of the pair of roller elements 13a, 13b is engaged with the axial one-side portion of the tube-side engagement concave-convex portion 20 of the coupling tube 14b so as to be axially displaceable, and the displacement to the axial one-side is prevented by the retainer ring 35a engaged with the inner peripheral surface of the end portion of the coupling tube 14b on the axial one side. In contrast, the roller element 13b on the other axial side engages the element-side engaging concave-convex portion 17 with the axially intermediate portion of the tube-side engaging concave-convex portion 20 of the connecting tube 14b so as to be axially displaceable. Accordingly, the pair of roller elements 13a, 13b and the coupling cylinder 14b integrally rotate.

In this example, the cam plate 27 of the loading cam device 7 is fitted and supported to the axial other side portion of the cylindrical portion 18b of the coupling cylinder 14b by the angular ball bearing 45 so as to be rotatable relative to the coupling cylinder 14b and not to be displaceable to the axial other side relative to the coupling cylinder 14 b. That is, the outer ring of the angular ball bearing 45 has an outer peripheral surface fitted in an inner peripheral surface of the end portion of the cylindrical portion 18b of the coupling tube 14b on the other side in the axial direction, and has a side surface on the other side in the axial direction abutted against a side surface on one side in the axial direction of the side plate portion 19 a. The inner ring of the angular ball bearing 45 is fitted with its inner peripheral surface on the outer peripheral surface of the end portion of the cylindrical portion 30 on one side in the axial direction of the cam plate 27, and with its one side surface in the axial direction abutted against the other side surface in the axial direction of the side plate portion 31.

In the friction roller reducer 1b of the present example, the elastic member 8i is constituted by combining a pair of belleville springs 36 having a truncated cone shape so as to have an opening on the outer diameter side thereof, and has a substantially V-shaped cross section. Therefore, the large-diameter side end portions of the pair of belleville springs 36 contact the front end surfaces (flat surface portions 16) of the pair of roller elements 13a, 13 b. Specifically, in this example, the pair of belleville springs 36 are overlapped in opposite axial directions so that the small diameter side end portions are abutted against each other. That is, the elastic member 8i is configured by combining two layers of the pair of belleville springs 36 in series.

According to the friction roller reducer 1b of the present embodiment, the occurrence of wear at the contact portion between the elastic member 8i and the pair of roller elements 13a and 13b can be suppressed.

That is, during operation of the friction roller reducer 1b, the portion of the pair of roller elements 13a, 13b in rolling contact with the intermediate roller 6 is pressed radially outward and elastically deformed. The elastically deformed portions of the pair of roller elements 13a, 13b move in the circumferential direction in association with the revolution movement of the intermediate roller 6. In this way, if the pair of roller elements 13a, 13b are elastically deformed periodically, there is a possibility that the tip surfaces of the pair of roller elements 13a, 13b rub against the elastic member 8i to cause fretting.

In this example, the elastic member 8i is formed by combining the pair of belleville springs 36 so that the outer diameter side thereof is opened and the cross section thereof is substantially V-shaped, so that the end portion on the large diameter side of the pair of belleville springs 36 is brought into contact with the distal end surfaces of the pair of roller elements 13a and 13 b. Therefore, according to the friction roller reducer 1b of the present embodiment, the contact area between the tip end surfaces of the pair of roller elements 13a and 13b and the contact portion of the elastic member 8i can be increased, and the contact surface pressure can be reduced, as compared with the case where the tip end surfaces of the pair of belleville springs on the small diameter side are brought into contact with the tip end surfaces of the pair of roller elements. Therefore, according to the friction roller reducer 1b of the present embodiment, fretting wear can be hardly generated at the contact portion of the elastic member 8i and the pair of roller elements 13a, 13 b. The other parts are similar in structure and operation to those of the first example of the first embodiment.

[ first example of the fourth embodiment ]

Fig. 18 to 21 show a first example of a fourth embodiment of the present invention. In the friction roller reducer 1c of the present example, the elastic member 8j is constituted by a single belleville spring 36. When the thickness is set to t (mm) and the total deflection is set to h ₀ In the case of (mm), the belleville spring 36 satisfies the relationship represented by the following formula (1).

h ₀ /t≤1.0…(1)

The height (free height) of the belleville spring 36 in the free state before the belleville springs 36 are disposed between the pair of roller elements 13a, 13b is set to H ₀ In the case of (mm), the total deflection h ₀ Can be represented by the following formula (2).

h ₀ ＝H ₀ －t…(2)

Total deflection h of belleville spring 36 ₀ Ratio h with respect to thickness t ₀ The lower limit value of t is larger than 0, and is not particularly limited as long as the belleville spring 36 is elastically deformable (functions as a spring) in response to the pressing force exerted by the loading cam device 7. However, the total deflection h is required ₀ The difference (cam stroke) between the interval L between the flat surface portions 16 of the pair of roller elements 13a, 13b in the initial state before the pressing force is exerted by the loading cam device 7 and the interval L when the pressing force exerted by the loading cam device 7 is maximum is set to be equal to or greater than the above. When such a case is considered, h ₀ The lower limit of t is about 0.5.

In the friction roller reducer 1c of this example, the total deflection h of the belleville springs 36 constituting the elastic member 8j ₀ Ratio h with respect to thickness t ₀ And/t is 1.0 or less. Therefore, it is possible to reliably prevent extreme slip from occurring in the region where the transmission torque of the friction roller reducer 1c is medium, and to reliably ensure the transmission efficiency of the friction roller reducer 1c while preventing deflection from occurring in the region where the transmission torque is large. The reason for this will be described with reference to fig. 20 and 21.

The outer diameter of the belleville spring 36 constituting the elastic member 8j in the free state is D (mm), the inner diameter is D (mm), the chamfer radius of the corner is R (mm), and the longitudinal elastic modulus of the material constituting the belleville spring 36 is E (N/mm ² ) When v is the poisson ratio and δ is the deflection, the spring load P of the belleville spring 36 is expressed by the following equation (3).

[ 1]

Further, C in formula (3) assuming that α=d/D ₁ Represented by the following formula (4).

[ 2]

The outer diameter D and the inner diameter D of the belleville spring 36 are limited by the size of the friction roller reducer 1c, and thus the degree of freedom of adjustment is limited. For example, in the case of the friction roller reducer 1c used in the drive system of an electric vehicle, the outer diameter of the ring roller 5 (the roller elements 13a, 13b constituting the ring roller 5) is about 150mm to 200 mm. The outer diameter D of the belleville spring 36 needs to be the same as the outer diameter of the ring roller 5 or less than the outer diameter of the ring roller 5, and the inner diameter D of the belleville spring 36 needs to be larger than the inner diameters of the large diameter side ends of the roller elements 13a, 13 b. Further, since the longitudinal elastic modulus E and poisson ratio v are determined by the material constituting the belleville spring 36, the degree of freedom of adjustment is low. Therefore, in the friction roller speed reducer 1c of the present example, the thickness t and the total deflection h of the belleville spring 36 are adjusted ₀ The relationship between the deflection δ of the belleville spring 36 and the force (spring load of the belleville spring 36) P applied to the pair of roller elements 13a, 13b by the elastic member 8j is adjusted.

FIG. 20 is a graph of total deflection h ₀ Ratio h with respect to thickness t ₀ And/t represents a graph of deflection delta of the belleville spring 36 versus the spring load P.

As is clear from fig. 20, if h ₀ When t is larger than 1.0, the amount of rise of the spring load P becomes smaller as the deflection δ becomes larger. I.e. at h ₀ When t is larger than 1.0, the nonlinearity of the spring characteristic of the belleville spring 36 becomes strong, and the rate of rise of the spring load P of the belleville spring 36 decreases in the region where the transmission torque of the friction roller reducer 1 is large. When a highly nonlinear belleville spring 36 having a spring characteristic is used as the elastic member 8j, if it is desired to ensure good transmission efficiency even in a region where the transmission torque of the friction roller reducer 1 is large, the friction roller reducer is worn as shown in fig. 21 (B)In the region where the transmission torque of the scrub roller reducer 1 is moderate, there is a possibility that the surface pressure of the traction portion between the rolling surface 21 and the inner diameter side rolling contact surface 11 and the outer diameter side rolling contact surface 12 is insufficient, and the running traction coefficient μ is larger than the limit traction coefficient μ _max Large. As a result, extreme slippage may occur. Alternatively, when the highly nonlinear belleville spring 36 having a spring characteristic is used as the elastic member 8j, the operating traction coefficient μ does not exceed the maximum value μ of the limit traction coefficient regardless of the transmission torque of the friction roller reducer 1c _max As shown in fig. 21C, in a region where the transmission torque of the friction roller reducer 1C is large, there is a possibility that the difference (margin) between the limit traction coefficient and the operation traction coefficient becomes large, the transmission efficiency is lowered, or the effect of preventing the acceleration increase of the pressing force due to the occurrence of the skew of the intermediate roller 6 is lowered.

Further, if no elastic member is provided between the pair of roller elements constituting the ring roller, as shown in fig. 21 (D), the load cam device generates a pressing force F proportional to the transmission torque of the friction roller speed reducer, so that the running traction coefficient μ becomes constant. On the other hand, as shown in fig. 55, the larger the surface pressure of the traction portion is, the limit traction coefficient μ _max The larger. Therefore, the larger the transmission torque of the friction roller reducer is, the limit traction coefficient μ _max The larger the difference (margin) from the running traction coefficient μ, the more easily the transmission efficiency decreases, or the more easily the effect of preventing the increase in the pressing force due to the generation of the intermediate roller decreases.

In contrast, in this example, since h ₀ Since t is 1.0 or less, the spring characteristic of the belleville spring 36 can be made substantially linear as shown in fig. 20. When the belleville spring 36 having a substantially linear spring characteristic is used as the elastic member 8j, as shown in fig. 21 (a), in the region where the transmission torque of the friction roller reducer 1c is medium, the surface pressure of the traction portion is insufficient, the running traction coefficient is larger than the limit traction coefficient, extreme slip can be prevented from occurring, and in the region where the transmission torque of the friction roller reducer 1c is large, the surface pressure of the traction portion can be prevented from becoming excessively large, The transfer efficiency can be well ensured. The other parts are similar in structure and operation to those of the first example of the first embodiment.

[ first example of fifth embodiment ]

Fig. 22 to 24 show a first example of a fifth embodiment of the present invention. The friction roller reducer 1d of the present example includes, between the front end surfaces (flat surface portions 16) of the pair of roller elements 13a, 13b, an elastic member 8k that elastically biases the pair of roller elements 13a, 13b in a direction in which the pair of roller elements 13a, 13b are separated from each other.

The friction roller reducer 1d of the present example includes an oil discharge path 46 that communicates the radially inner side and the radially outer side of the space between the pair of roller elements 13a and 13 b. For this reason, in this example, each of the belleville springs 36a has cutouts 47 at a plurality of circumferentially equally spaced portions of the outer peripheral edge. In other words, each belleville spring 36a has a gear-like concave-convex portion at the outer peripheral edge.

The elastic member 8k is configured by overlapping two belleville springs 36a in opposite axial directions so that the small diameter side ends are abutted against each other, that is, by combining two layers in series. In a state where the elastic member 8k is disposed between the distal end surfaces of the pair of roller elements 13a and 13b, the radially inner side and the radially outer side of the opposing space between the pair of roller elements 13a and 13b, including the elastic member 8k, communicate with each other through the slit 47 provided in each belleville spring 36 a. That is, in this example, the cutout 47 constitutes the oil discharge path 46 that communicates the radially inner side and the radially outer side of the opposing space between the pair of roller elements 13a and 13b including the elastic member 8k. That is, the oil discharge passage 46 is formed in a portion between the one side coil spring 36a in the axial direction and the one side roller element 13a in the axial direction and in a portion between the other side coil spring 36a in the axial direction and the other side roller element 13b in the axial direction.

As described above, in the friction roller reducer 1d of the present example, the cutouts 47 are provided at a plurality of circumferentially equally spaced locations on the outer peripheral edges of the two belleville springs 36a that constitute the elastic member 8k, and the cutouts 47 constitute the oil discharge passages 46 that communicate the radially inner side and the radially outer side of the opposing space between the pair of roller elements 13a, 13b, including the elastic member 8 k. Therefore, it is possible to prevent the lubricant oil from being accumulated in the space which exists inside the elastic member 8k in the radial direction and is surrounded by the inner peripheral surface of the elastic member 8, the mutually opposed axial side surfaces of the pair of roller elements 13a, 13b, and the rolling surface 21 of the intermediate roller 6.

That is, in the case where the friction roller reducer does not include the oil discharge passage that communicates the radially inner side and the radially outer side of the opposing space between the pair of roller elements including the elastic member, the lubricating oil is accumulated in the space that exists radially inner side of the elastic member. Further, if the lubricating oil is accumulated in the space, stirring resistance increases, and rotation resistance of the intermediate roller increases, and there is a possibility that efficiency of the friction roller reducer may decrease.

In contrast, in the friction roller reducer 1d of the present example, since the oil discharge path 46 that communicates the radially inner side and the radially outer side of the opposing space between the pair of roller elements 13a and 13b is provided so as to include the elastic member 8k, the lubricating oil that is present in the radially inner side of the opposing space can be smoothly discharged to the radially outer side of the opposing space. Therefore, the lubricant oil can be prevented from accumulating inside the opposing space in the radial direction, and the increase in the rotational resistance of the intermediate roller 6 caused by the increase in the stirring resistance of the lubricant oil can be prevented. As a result, the efficiency of the friction roller reducer 1d can be prevented from decreasing. The other parts are similar in structure and operation to those of the first example of the first embodiment.

[ second example of fifth embodiment ]

Fig. 25 and 26 show a second example of the fifth embodiment of the present invention. In this example, the elastic member 8l disposed between the distal end surfaces of the pair of roller elements 13a, 13b includes two belleville springs 36b having a truncated cone shape. Each of the belleville springs 36b has notches 47a at a plurality of circumferentially equally spaced locations on the inner periphery. In other words, each belleville spring 36b has a gear-like concave-convex portion at the inner periphery.

The elastic member 8l is configured by overlapping two belleville springs 36b in opposite axial directions so that the ends on the large diameter side are abutted against each other, that is, by combining two layers in series. In a state where the elastic member 8l is disposed between the distal end surfaces of the pair of roller elements 13a, 13b, the radially inner side and the radially outer side of the opposing space between the pair of roller elements 13a, 13b, including the elastic member 8l, communicate with each other through the cutout 47a provided in each belleville spring 36b. That is, in this example, the cutout 47a constitutes the oil discharge path 46a that communicates the radially inner side and the radially outer side of the opposing space between the pair of roller elements 13a and 13b, including the elastic member 8 l. That is, the oil discharge passage 46a is formed in a portion between the one side coil spring 36b in the axial direction and the one side roller element 13a in the axial direction and in a portion between the other side coil spring 36b in the axial direction and the other side roller element 13b in the axial direction, respectively.

In this example, the lubricating oil present in the radial direction inside of the opposing space can be smoothly discharged to the radial direction outside of the opposing space through the oil discharge passage 46 a. Therefore, the lubricant oil can be prevented from accumulating inside the opposing space in the radial direction, and the increase in the rotational resistance of the intermediate roller 6 caused by the increase in the stirring resistance of the lubricant oil can be prevented. The configuration and operational effects of the other parts are the same as those of the first example of the first embodiment and the first example of the fifth embodiment.

[ third example of fifth embodiment ]

Fig. 27 and 28 show a third example of the fifth embodiment of the present invention. In this example, the elastic member 8m disposed between the distal end surfaces of the pair of roller elements 13a, 13b is constituted by a single belleville spring 36c having a truncated cone shape. The belleville spring 36c has cutouts 47 at circumferentially equally spaced locations on the outer periphery and cutouts 47a at circumferentially equally spaced locations on the inner periphery. In other words, the belleville spring 36c has a gear-like concave-convex portion at the outer peripheral edge, and a gear-like concave-convex portion at the inner peripheral edge.

In a state where the elastic member 8m is disposed between the distal end surfaces of the pair of roller elements 13a, 13b, the radially inner side and the radially outer side of the opposing space between the pair of roller elements 13a, 13b communicate with each other through the cutouts 47, 47a provided in the belleville spring 36 c. That is, in this example, the notches 47 and 47a constitute the oil discharge path 46b that communicates the radially inner side and the radially outer side of the space between the pair of roller elements 13a and 13b, including the elastic member 8 m.

In this example, the lubricant oil present inside the opposing space in the radial direction can be smoothly discharged to the outside of the opposing space in the radial direction through the oil discharge path 46b formed by the cutouts 47, 47 a. Therefore, the lubricant can be discharged more effectively than the structure of the first example of the fifth embodiment. The configuration and operational effects of the other parts are the same as those of the first example of the first embodiment and the first example of the fifth embodiment.

[ fourth example of fifth embodiment ]

Fig. 29 and 30 show a fourth example of the fifth embodiment of the present invention. In this example, the elastic member 8i disposed between the distal end surfaces of the pair of roller elements 13a and 13b includes two belleville springs 36 having a truncated cone shape. The elastic member 8i is configured by overlapping two belleville springs 36 so that the small diameter side ends are abutted against each other, that is, by combining two layers in series. Further, each belleville spring 36 has no cutout at both the outer and inner peripheral edges.

In this example, a hollow circular plate-like shim plate 48 is sandwiched between the end surfaces of the pair of roller elements 13a, 13b and the end portions of the large diameter sides of the respective belleville springs 36. Each of the shim plates 48 has grooves 49 in the radial direction at a plurality of circumferentially equally spaced portions on the side surfaces of the opposite axial sides of the belleville spring 36. That is, the groove 49 opens at the axial side face, the outer periphery, and the inner periphery of the pad 48.

In this example, the radially inner side and the radially outer side of the facing space between the pair of roller elements 13a, 13b communicate with each other through the grooves 49 provided in the respective backing plates 48. That is, in this example, the groove 49 forms the oil discharge path 46c that communicates the radially inner side and the radially outer side of the opposing space between the pair of roller elements 13a and 13b including the elastic member 8 i. That is, the oil discharge path 46c is formed in a portion between the one axial shim plate 48 and the one axial roller element 13a, a portion between the one axial shim plate 48 and the one axial belleville spring 36, a portion between the other axial shim plate 48 and the other axial roller element 13b, and a portion between the other axial shim plate 48 and the other axial belleville spring 36, respectively. In this example, the lubricant oil present in the radial inner side of the opposing space can be smoothly discharged to the radial outer side of the opposing space through the oil discharge passage 46c formed by the groove 49.

Further, instead of the grooves, radially extending convex strips may be formed at a plurality of circumferential positions on the axial side surface of the pad plate. In this case, the oil discharge path is formed by a portion between the ridges adjacent in the circumferential direction. Therefore, the cross-sectional area of the oil discharge passage can be increased, and the effect of discharging the lubricating oil can be improved. The configuration and operational effects of the other parts are the same as those of the first example of the first embodiment and the first example of the fifth embodiment.

[ fifth example of fifth embodiment ]

Fig. 31 and 32 show a fifth example of a fifth embodiment of the present invention. In this example, between the distal end surfaces of the pair of roller elements 13a, 13b, elastic members 8i are arranged, each of which is formed by overlapping two belleville springs 36 so that the small diameter side ends are abutted against each other.

In this example, a tooth lock washer 50 having a substantially hollow circular plate shape is sandwiched between the end surfaces of the pair of roller elements 13a and 13b and the end of the large diameter side of each belleville spring 36. Each tooth lock washer 50 has notches 51 at a plurality of circumferential locations on the outer periphery. In other words, the tooth lock washer 50 has a gear-like concave-convex portion at the outer peripheral edge.

In this example, the radially inner side and the radially outer side of the facing space between the pair of roller elements 13a, 13b communicate with each other through the cutout 51 provided in each tooth lock washer 50. That is, in this example, the oil discharge path 46d that communicates the radially inner side and the radially outer side of the opposing space between the pair of roller elements 13a, 13b including the elastic member 8i is formed by the cutout 51. That is, the oil drain 46d is formed in a portion between the tooth lock washer 50 on one axial side and the belleville spring 36 on the one axial side and a portion between the tooth lock washer 50 on the other axial side and the belleville spring 36 on the other axial side, respectively. In this example, the lubricant oil present in the radial inner side of the opposing space can be smoothly discharged to the radial outer side of the opposing space through the oil discharge passage 34d formed by the cutout 51. The configuration and operational effects of the other parts are the same as those of the first example of the first embodiment and the first example of the fifth embodiment.

[ sixth example of fifth embodiment ]

Fig. 33 shows a sixth example of the fifth embodiment of the present invention. In this example, the elastic member 8n disposed between the front end surfaces of the pair of roller elements 13a and 13b has a cylindrical shape, and is made of a material having elasticity such as an elastomer like rubber. The elastic member 8n has grooves 52 in a plurality of circumferential portions on the other axial side surface, and extends radially. That is, the groove 52 is opened on the other side surface in the axial direction of the elastic member 8n, the outer peripheral surface, and the inner peripheral surface.

In this example, the radially inner side and the radially outer side of the facing space, which is present between the pair of roller elements 13a, 13b and in which the elastic member 8n is disposed, communicate with each other through the groove 52 provided in the side surface on the other side in the axial direction of the elastic member 8 n. That is, in this example, the oil discharge passage 46e is constituted by the groove 52. Further, the lubricating oil present in the radial direction inside of the opposing space can be smoothly discharged to the radial direction outside of the opposing space through the oil discharge passage 46e. The configuration and operational effects of the other parts are the same as those of the first example of the first embodiment and the first example of the fifth embodiment.

Seventh example of the fifth embodiment

Fig. 34 and 35 show a seventh example of the fifth embodiment of the present invention. In this example, the pair of roller elements 13e and 13f have grooves 53 in a plurality of positions at equal intervals in the circumferential direction of the front end surfaces (flat surface portions 16) facing each other, in the radial direction. That is, the grooves 53 are opened at the front end surfaces, outer peripheral surfaces, and inner peripheral surfaces of the roller elements 13e, 13 f. In this example, the groove 53 has a circular arc-shaped cross-sectional shape.

An elastic member 8i composed of two flat belleville springs 36 having a truncated cone shape is sandwiched between the tip end surfaces of the pair of roller elements 13e, 13 f. The elastic member 8i is configured by overlapping two belleville springs 36 so that the small diameter side ends are abutted against each other, that is, by combining two layers in series. Further, each belleville spring 36 has no cutout at both the outer and inner peripheral edges.

In this example, the radially inner side and the radially outer side of the facing space, which is present between the pair of roller elements 13e, 13f and in which the elastic member 8i is disposed, communicate with each other through the groove 53 provided in the distal end surfaces of the pair of roller elements 13e, 13 f. That is, in this example, the oil discharge passage 46f is constituted by the groove 53. Further, the lubricating oil present in the radial direction inside of the opposing space can be smoothly discharged to the radial direction outside of the opposing space through the oil discharge passage 46f.

In this example, the cross-sectional shape of the groove 53 is circular arc. Therefore, when torque is transmitted by the friction roller reducer 1, stress concentration at the portions of the roller elements 13e, 13f where the grooves 53 are formed can be prevented. The configuration and operational effects of the other parts are the same as those of the first example of the first embodiment and the first example of the fifth embodiment.

Eighth example of the fifth embodiment

Fig. 36 shows an eighth example of the fifth embodiment of the present invention. In this example, the elastic member disposed between the tip end surfaces of the pair of roller elements 13a and 13b (see fig. 22 and 23) has a truncated cone shape, and is composed of two belleville springs 36d that are stacked in opposite axial directions. Each of the belleville springs 36d has a through hole 54 penetrating a plurality of portions (four portions in the illustrated example) in the circumferential direction of the radially intermediate portion. That is, in a state where the elastic member is disposed between the distal end surfaces of the pair of roller elements 13a and 13b, the radially inner side and the radially outer side of the facing space in which the elastic member is disposed, which is present between the pair of roller elements 13a and 13b, communicate with each other through the through hole 54 provided in each belleville spring 36 d. That is, in this example, the through hole 54 constitutes an oil discharge passage that communicates the inside in the radial direction with the outside in the radial direction of the opposing space between the pair of roller elements 13a, 13b including the elastic member. The configuration and operational effects of the other parts are the same as those of the first example of the first embodiment and the first example of the fifth embodiment.

In the case of implementing the friction roller reducer of the present embodiment, various configurations can be adopted as long as an oil discharge path that communicates the radially inner side and the radially outer side of the opposing space in which the elastic member is disposed, which exists between the pair of roller elements, can be ensured.

For example, as shown in fig. 8 showing the fifth example of the first embodiment, the elastic member 8d as a wave washer can be sandwiched between the front end surfaces (flat surface portions 16) of the pair of roller elements 13a, 13 b. The wave washer has a wave shape in the circumferential direction. That is, in a state in which the wave washers are disposed between the front end surfaces of the pair of roller elements 13a, 13b, oil discharge passages that communicate the radially inner sides and the radially outer sides of the facing spaces between the pair of roller elements 13a, 13b are formed at a plurality of positions in the circumferential direction between the axial side surfaces of the elastic member 8d and the front end surfaces of the pair of roller elements 13a, 13 b.

Alternatively, as shown in fig. 9 showing the sixth example of the first embodiment, the elastic member 8e formed of the torsion coil spring 37 may be sandwiched between the front end surfaces (flat surface portions 16) of the pair of roller elements 13a, 13 b. The torsion coil spring 37 is formed by winding a metal wire into a spiral shape. Accordingly, in a state where the torsion coil springs 37 are disposed between the distal end surfaces of the pair of roller elements 13a, 13b, the oil discharge passage that communicates the radially inner side and the radially outer side of the facing space between the pair of roller elements 13a, 13b is formed by the gaps between the axially adjacent portions of the wires constituting the torsion coil springs 37.

[ first example of sixth embodiment ]

A first example of the sixth embodiment of the present invention will be described with reference to fig. 37 to 44. The friction roller speed reducer according to one embodiment of the present invention includes an elastic member that elastically biases the pair of roller elements in a direction away from the rolling surface of the intermediate roller. In addition, in the loading cam device, a preload spring may be incorporated in a compressed state between the roller element and the cam plate. The preload spring elastically presses the roller member and the cam plate in a direction to separate the roller member and the cam plate from each other. Therefore, in the loading cam device including the preload spring, the pressing force by the elastic force of the preload spring is exerted in the preload region from the state before the torque is input to the input shaft until the amount of the jump-up of the rolling element from the bottom of the recess of the driving side cam surface and from the bottom of the recess of the driven side cam surface increases to a certain extent, so that the necessary minimum surface pressure can be applied to the traction portion immediately after the start of the operation of the friction roller reducer (immediately after the start of the torque input to the input shaft).

Here, as shown in fig. 55, the larger the torque transmitted by the friction roller reducer is, the larger the surface pressure P of the traction portion is, the maximum limit traction coefficient μ is _max The larger. Conversely, the smaller the torque transmitted by the friction roller reducer, the smaller the surface pressure P of the traction portion, the maximum limit traction coefficient μ _max The smaller. Therefore, in a region where the torque transmitted by the friction roller reducer is small, if the force applied by the elastic member to the pair of roller elements to elastically urge the pair of roller elements in a direction away from the rolling surface of the intermediate roller becomes excessive, the surface pressure P of the traction portion may be insufficient, and extreme slippage may occur.

In order to reliably prevent the occurrence of extreme slip in the region where the torque transmitted by the friction roller reducer is small, for example, as shown in fig. 43, it is conceivable to provide a gap 55 between the elastic member 8z and one roller element 13a of the pair of roller elements 13a, 13 b. If the gap 55 is provided, as shown in fig. 44, in the region where the torque transmitted by the friction roller reducer is small, the force in the direction of separation generated by the elastic recovery of the elastic member 8z does not act on the pair of roller elements 13a and 13 b. Therefore, in the region where the torque transmitted by the friction roller reducer is small and the surface pressure of the traction portion is small, the maximum limit traction coefficient μ can be prevented _max And is unnecessarily small, so that the occurrence of extreme slip can be reliably prevented.

As the torque transmitted by the friction roller reducer becomes larger, the gap 55 becomes smaller. When the gap 55 disappears, the one roller element 13a comes into contact with the elastic member 8z and the elastic member 8z starts to elastically deform, and the elastic member 8z starts to apply a force in a direction of separating the pair of roller elements 13a and 13b from each other. As shown in fig. 44, the larger the torque transmitted by the friction roller reducer, the larger the force applied to the pair of roller elements 13a, 13b by the elastic member 8 z.

However, if the gap 55 is too large, the elastic member 8z is greatly displaced between the pair of roller elements 13a and 13b, and abnormal sound or abrasion may occur. And/or, when the torque transmitted by the friction roller reducer is increased, the force applied by the elastic member 8z to the pair of roller elements 13a, 13b cannot be set to a desired level, and there is a possibility that the efficiency of the friction roller reducer is lowered or damage such as heat generation and sticking occurs. Therefore, the size of the gap 55 in the initial state before the torque is input to the input shaft needs to be limited with high accuracy.

In the region where the torque transmitted by the friction roller reducer is small, the gap 55 is not necessarily provided as long as the occurrence of extreme slip can be prevented. That is, in the initial state, the elastic member can be held between the front end surfaces of the pair of roller elements in an uncompressed or slightly compressed state. In other words, in the initial state, the end portions of the elastic member may be brought into contact with the distal end surfaces of the pair of roller elements in a state in which the elastic member is not compressed or is slightly compressed. In this case, when the torque transmitted by the friction roller reducer increases, in order to set the force applied by the elastic member to the pair of roller elements to a desired level, it is also necessary to precisely limit the distance between the distal end surfaces of the pair of roller elements in the initial state and the contact state between the distal end surfaces of the pair of roller elements and the elastic member.

In the conventional friction roller reducer 100 shown in fig. 54, in its assembled state, the peripheries of the pair of roller elements 110a, 110b are covered with the connecting tube 111. Therefore, after the sun roller 103, the pair of roller elements 110a and 110b, and the plurality of intermediate rollers 105 are disposed radially inward of the connecting tube 111, the distal end surfaces of the pair of roller elements 110a and 110b cannot be visually confirmed from the outside. Therefore, in the conventional friction roller reducer 100, it is difficult to precisely limit the distance between the front end surfaces of the pair of roller elements and the contact state between the front end surfaces of the pair of roller elements and the elastic member.

The present embodiment aims to provide a friction roller speed reducer which can visually confirm the front end surfaces of a pair of roller elements from the outside even after a sun roller, a pair of roller elements and a plurality of intermediate rollers are arranged on the radial inner side of a connecting cylinder.

In the friction roller reducer 1e of the present example, the ring roller 5c is configured by combining the pair of roller elements 13a, 13b by the coupling cylinder 14c so as to be capable of relative displacement in the axial direction and not capable of relative rotation. The coupling tube 14c has a cylindrical portion 18c and a side plate portion 19a bent radially inward from the other end portion of the cylindrical portion 18a in the axial direction.

The elastic member 8o is disposed between the front end surfaces of the pair of roller elements 13a, 13b, that is, between the flat surface portions 16 facing each other as shown in fig. 39. In this example, the elastic member 8o is formed by combining a pair of belleville springs 36 so that the outer diameter side thereof is open, and has a substantially V-shaped cross section.

In this example, the elastic member 8o is not elastically compressed in the initial state before the pressing force is exerted by the cam device 7 due to the increase in the amount of jump from the bottom of the recess of the driving side cam surface 29 and the bottom of the recess of the driven side cam surface 32 of the rolling element 28. Specifically, as shown in fig. 39, a gap 55 is provided between the end portion on one side in the axial direction of the elastic member 8o and the flat surface portion 16 of the roller element 13a on the one side in the axial direction, and the end portion on the other side in the axial direction of the elastic member 8o abuts against the flat surface portion 16 of the roller element 13b on the other side in the axial direction.

Further, the end portion on one side in the axial direction of the elastic member 8o may be brought into contact with the flat surface portion 16 of the roller element 13a on the one side in the axial direction, and a gap may be provided between the end portion on the other side in the axial direction of the elastic member 8o and the flat surface portion 16 of the roller element 13b on the other side in the axial direction. Alternatively, a gap may be provided between the end portions of the elastic member 8o on both axial sides and the flat surface portions 16 of the respective roller elements 13a, 13 b. In any case, by providing the gap 55 between the elastic member 8o and the roller elements 13a and 13b, a force in a direction of separating the pair of roller elements 13a and 13b from the elastic member 8o is not applied in the initial state.

In this example, the connecting tube 14c has an opening 42a through which the front end surfaces (flat surface portions 16) of the pair of roller elements 13a, 13b facing each other can be visually recognized. That is, as shown in fig. 39 to 42, the cylindrical portion 18c of the coupling tube 14c is formed by alternately arranging the concave portions 56 and the convex portions 57 extending in the axial direction in the circumferential direction, and a plurality of oil discharge holes 58a, 58b are provided in each of the convex portions 57 so as to penetrate the cylindrical portion 18c in the radial direction.

Each of the oil discharge holes 58a, 58b has an oblong opening shape elongated in the axial direction. The axial length of the oil discharge hole 58b is longer than that of the oil discharge hole 58 a. In addition, the shape and size of the plurality of oil discharge holes 58a are equal among all the oil discharge holes 58 a.

The oil discharge holes 58a and 58b are holes for discharging the lubricating oil supplied to the portion where the members such as the traction portion of the friction roller reducer 1 contact each other, from the inside of the connecting tube 14c, in order to circulate the lubricating oil. The lubricating oil discharged from the oil discharge holes 58a and 58b is temporarily stored in an oil pan, not shown, and is then supplied again into the connecting tube 14 c.

The oil discharge holes 58b are provided at a plurality of positions (four to five positions in this example) at equal intervals in the circumferential direction of the cylindrical portion 18 c. The axial length of the oil discharge hole 58b is longer than the distance L between the flat surface portions 16 of the pair of roller elements 13a, 13b in the above-described initial state.

In this example, the oil drain hole 58b constitutes an opening 42a through which the opposing front end surfaces (flat surface portions 16) of the pair of roller elements 13a, 13b can be visually recognized. That is, the opening 42a (the oil drain hole 58 b) has a size (axial length and circumferential width) that can confirm the contact state of the elastic member 8o with the roller elements 13a and 13 b. In this example, the opening 42a (oil drain hole 58 b) has an axial length longer than the distance L between the flat surface portions 16 of the pair of roller elements 13a, 13 b. The opening 42a has a size including the pair of roller elements 13a and 13 b. In other words, the front end surface (flat surface portion 16) of the roller element 13a on one side in the axial direction is located on the other side in the axial direction than the end portion on one side in the axial direction of the opening 42a, and the front end surface (flat surface portion 16) of the roller element 13b on the other side in the axial direction is located on the one side in the axial direction than the end portion on the other side in the axial direction of the opening 42a. In this example, the other end portion of the opening 42a in the axial direction is located radially outward of the axial intermediate portion of the cam plate 27. That is, one axial side portion of the cam plate 27 can be visually checked through the opening 42a.

In the present embodiment, the "contact state" includes not only a state in which the elastic member 8o contacts the roller elements 13a and 13b, but also a state in which the elastic member 8o is disposed with a gap 55 with respect to at least one of the pair of roller elements 13a and 13b, in other words, a state in which at least one of the roller elements and the elastic member 8o face each other through the gap 55. The front end surfaces (flat surface portions 16) of the pair of roller elements 13a and 13b that face each other can be visually observed not only the entire front end surfaces of the roller elements 13a and 13b but also the portions of the front end surfaces of the roller elements 13a and 13b that face the opening 42a, in other words, the areas located inside the opening 42a.

The oil drain holes 58a are provided in a plurality of (four in this example) axially equally spaced portions of the protruding portion 57 of the cylindrical portion 18c, the protruding portion 57 not having the oil drain holes 58 b.

In the friction roller reducer 1e of the present example, the coupling cylinder 14c that supports the pair of roller elements 13a and 13b so as to be capable of relative displacement in the axial direction and incapable of relative rotation has an opening 42a (oil drain hole 58 b) that allows the visual observation of the front end surfaces (flat surface portions 16) of the pair of roller elements 13a and 13b that face each other. Thus, even after the sun roller 4, the pair of roller elements 13a, 13b, and the plurality of intermediate rollers 6 are disposed radially inward of the connecting tube 14c, the distal end surfaces of the pair of roller elements 13a, 13b and the elastic member 8o disposed between the distal end surfaces can be visually confirmed from the outside.

Therefore, after the friction roller reducer 1e is assembled, a measuring instrument such as a vernier caliper is inserted from the opening 42a between the mutually opposed front end surfaces of the pair of roller elements 13a, 13b, and the axial distance between the front end surfaces can be measured, and the position of the elastic member 8o can be confirmed. Therefore, the axial distance between the opposing front end surfaces of the pair of roller elements 13a, 13b and the size of the gap 55 can be restricted with high accuracy, and the elastic member 8o can be appropriately arranged between the opposing front end surfaces of the pair of roller elements 13a, 13b in the initial state.

The opening 42a is sized to confirm the contact state between the elastic member 8o and the roller elements 13a and 13 b. Therefore, in this example, after the friction roller reducer 1e is assembled, the contact state between the elastic member 8 and the roller elements 13a and 13b can be checked through the opening 42a, and whether or not the elastic member 8o is forgotten or erroneously assembled, whether or not the elastic member 8o is properly assembled, and the like can be checked.

In this example, the opening 42a for allowing visual observation of the opposing front end surfaces of the pair of roller elements 13a, 13b is formed by the oil drain hole 58 b. Therefore, only the end surfaces of the pair of roller elements 13a, 13b facing each other need be visually recognized, and an opening need not be provided in the cylindrical portion 18c of the connecting tube 14 c.

However, in a case where the oil discharge hole for discharging the lubricating oil in the coupling cylinder is not provided in the cylindrical portion of the coupling cylinder, an opening portion for allowing visual observation of the mutually opposed distal end surfaces of the pair of roller elements may be provided in the cylindrical portion.

In this example, since the openings 42a (the oil discharge holes 58 b) are provided at a plurality of circumferentially equally spaced locations of the cylindrical portion 18c, the distance between the distal end surfaces of the pair of roller elements 13a, 13b can be measured at a plurality of circumferentially spaced locations after the sun roller 4, the pair of roller elements 13a, 13b, and the plurality of intermediate rollers 6 are disposed radially inward of the connecting tube 14 c. Therefore, the parallelism of the front end surfaces of the pair of roller elements 13a, 13b can be confirmed.

In this example, since the gap 55 is provided between the elastic member 8o and the roller element 13a on one axial side, the pair of roller elements 13a and 13b are not acted on the force in the direction of separation due to elastic restoration of the elastic member 8o in the region where the torque transmitted by the friction roller reducer 1e is small. Therefore, in a low torque region where the torque transmitted by the friction roller reducer 1e is small and the surface pressure of the traction portion is small, the traction coefficient can be prevented from becoming excessively small, and the occurrence of extreme slip can be prevented more reliably.

In this example, the structure in which the gap 55 is provided between the elastic member 8o and the roller element 13a on one axial side is described, but the friction roller speed reducer of the present embodiment can also be applied to a structure in which the elastic member is sandwiched between the tip end surfaces of the pair of roller elements in an uncompressed or slightly compressed state in an initial state. In this case, the distance between the front end surfaces of the pair of roller elements in the initial state and the contact state between the front end surfaces of the pair of roller elements and the elastic member can be accurately regulated, and when the torque transmitted by the friction roller reducer increases, the force applied by the elastic member to the pair of roller elements can be set to a desired level.

Second to fourth examples of the sixth embodiment

In the present embodiment, in the case where the elastic member is constituted by a belleville spring, for example, as shown in fig. 45 to 47, the number of belleville springs and/or the combination method and the like can be appropriately determined according to the magnitude of the elastic force required by the elastic member. However, in the case where the elastic member is constituted by a belleville spring, it is preferable to suppress the number of belleville springs as small as possible in order to suppress the influence of hysteresis of the spring characteristics to be small.

In the second example of the sixth embodiment shown in fig. 45, the elastic member 8p is constituted by a single belleville spring 36. A gap 55 is provided between one end portion of the elastic member 8p in the axial direction and the front end surface (flat surface portion 16) of the roller element 13a in the axial direction, and the other end portion of the elastic member 8p in the axial direction is brought into contact with the front end surface (flat surface portion 16) of the roller element 13b in the axial direction.

In the third example of the sixth embodiment shown in fig. 46, the elastic member 8q is configured by overlapping two belleville springs 36 of the three belleville springs 36 in the same direction and overlapping the remaining belleville springs 36 in opposite directions. A gap 55 is provided between one end in the axial direction of the elastic member 8q and the front end surface (flat surface portion 16) of the roller element 13a on one side in the axial direction, and the other end in the axial direction of the elastic member 8q is brought into contact with the front end surface (flat surface portion 16) of the roller element 13b on the other side in the axial direction.

In the fourth example of the sixth embodiment shown in fig. 47, the elastic member 8r is configured by combining two belleville springs 36 of the four belleville springs 36 in the same direction and overlapping them in opposite directions, that is, by combining two belleville springs in parallel and two layers in series. A gap 55 is provided between one end portion of the elastic member 8r in the axial direction and the front end surface (flat surface portion 16) of the roller element 13a in the axial direction, and the other end portion of the elastic member 8r in the axial direction is brought into contact with the front end surface (flat surface portion 16) of the roller element 13b in the axial direction.

In the second to fourth examples of the sixth embodiment, the elastic member may be held between the front end surfaces of the pair of roller elements in an uncompressed or slightly compressed state in the initial state. In this case, the distance between the front end surfaces of the pair of roller elements in the initial state and the contact state between the front end surfaces of the pair of roller elements and the elastic member can be accurately regulated, and when the torque transmitted by the friction roller reducer increases, the force applied by the elastic member to the pair of roller elements can be set to a desired level.

Fifth to eighth examples of the sixth embodiment

Fig. 48 to 51 show examples in which the elastic member is constituted by a member other than a belleville spring.

In a fifth example of the sixth embodiment shown in fig. 48, the elastic member 8s is constituted by a wave washer. A gap 55 is provided between one end portion of the elastic member 8s in the axial direction and the front end surface (flat surface portion 16) of the roller element 13a in the axial direction, and the other end portion of the elastic member 8s in the axial direction is brought into contact with the front end surface (flat surface portion 16) of the roller element 13b in the axial direction.

In a sixth example of the sixth embodiment shown in fig. 49, the elastic member 8t is constituted by a torsion coil spring 37. The torsion coil springs 37 may be disposed one between the front end surfaces of the pair of roller elements 13a and 13b, or may be provided in plural locations at equal intervals in the circumferential direction between the front end surfaces of the pair of roller elements 13a and 13 b. A gap 55 is provided between one end portion of the elastic member 8t in the axial direction and the front end surface (flat surface portion 16) of the roller element 13a in the axial direction, and the other end portion of the elastic member 8t in the axial direction is brought into contact with the front end surface (flat surface portion 16) of the roller element 13b in the axial direction.

In a seventh example of the sixth embodiment shown in fig. 50, the elastic member 8u includes a plurality of torsion coil springs 37. In this example, a plurality of axially recessed holding recesses 38 are provided at circumferentially equally spaced locations on the distal end surface of the roller element 13d on the other axial side of the pair of roller elements 13a, 13d constituting the ring roller 5 a. The torsion coil springs 37 are inserted into the holding concave portions 38 at the other end portions in the axial direction. A gap 55 is provided between one end portion of the elastic member 8u in the axial direction and the front end surface (flat surface portion 16) of the roller element 13a in the axial direction.

In an eighth example of the sixth embodiment shown in fig. 51, the elastic member 8v includes a plurality of torsion coil springs 37. The friction roller speed reducer of the present example has a holder 39 for holding a plurality of torsion coil springs 37. The retainer 39 has a hollow circular plate shape, and has retaining holes 40 penetrating in the axial direction at a plurality of positions equally spaced in the circumferential direction. Each torsion coil spring 37 is inserted through the axial intermediate portion inside the holding hole 40. A gap 55 is provided between the one end portion of the elastic member 8v in the axial direction and the front end surface (flat surface portion 16) of the one roller element 13a in the axial direction, and the other end portion of the elastic member 8v in the axial direction is brought into contact with the front end surface (flat surface portion 16) of the other roller element 13b in the axial direction.

In the fifth to eighth examples of the sixth embodiment, the elastic member may be held between the front end surfaces of the pair of roller elements in an uncompressed or slightly compressed state in the initial state. In this case, the distance between the front end surfaces of the pair of roller elements in the initial state and the contact state between the front end surfaces of the pair of roller elements and the elastic member can be accurately regulated, and when the torque transmitted by the friction roller reducer increases, the force applied by the elastic member to the pair of roller elements can be set to a desired level.

Ninth example of sixth embodiment

Fig. 52 shows a ninth example of the sixth embodiment. In the friction roller reducer of the present example, the shape and the number of the openings 42b, 42c provided in the cylindrical portion 19d of the connecting tube 14d so that the front end surfaces (flat surface portions 16) of the pair of roller elements 13a, 13b can be visually recognized in the assembled state are different from those of the first example of the sixth embodiment.

In this example, the coupling tube 14d has a pair of openings 42b, 42c through which the opposing front end surfaces (flat surface portions 16) of the pair of roller elements 13a, 13b can be visually recognized. The pair of openings 42b and 42c have a circular opening shape. The pair of openings 42b and 42c are provided at two positions in the axial direction of the plurality of circumferential portions of the cylindrical portion 19d of the coupling tube 14 d. The openings 42b and 42c also function as oil drain holes.

The opening 42b is disposed at a position where one end portion including the front end surface (flat surface portion 16) in the axial direction of the one-side roller element 13a can be visually observed, and the opening 42b is disposed at a position where the other end portion including the front end surface (flat surface portion 16) in the axial direction of the other-side roller element 13b can be visually observed. The ends of the elastic member 8o on both sides in the axial direction can be visually inspected from the openings 42b and 42c, respectively. Accordingly, the openings 42b and 42c have a size capable of confirming the contact state between the elastic member 8o and the roller elements 13a and 13 b.

In the friction roller reducer of this example, the coupling cylinder 14d that supports the pair of roller elements 13a and 13b so as to be capable of relative displacement in the axial direction and incapable of relative rotation has openings 42b and 42c that allow visual inspection of the front end surfaces (flat surface portions 16) of the pair of roller elements 13a and 13b that face each other. Thus, even after the sun roller 4, the pair of roller elements 13a, 13b, and the plurality of intermediate rollers 6 are disposed radially inward of the connecting tube 14c, the distal end surfaces of the pair of roller elements 13a, 13b and the elastic member 8o disposed between the distal end surfaces can be visually confirmed from the outside.

Therefore, according to the friction roller reducer of the present example, as in the first example of the sixth embodiment, after the friction roller reducer is assembled, a measuring instrument such as a vernier caliper is inserted between the mutually opposed front end surfaces of the pair of roller elements 13a, 13b from the opening portions 42b, 42c, the axial distance between the front end surfaces can be measured, and the position of the elastic member 8v can be confirmed. Therefore, the axial distance between the opposing front end surfaces of the pair of roller elements 13a, 13b and the size of the gap 55 can be restricted with high accuracy, and the elastic member 8v can be appropriately arranged between the opposing front end surfaces of the pair of roller elements 13a, 13b in the initial state.

The openings 42b and 42c are sized to confirm the contact state between the elastic member 8v and the roller elements 13a and 13 b. Therefore, in this example, after the friction roller reducer is assembled, the contact state between the elastic member 8v and the roller elements 13a and 13b can be checked through the openings 42b and 42c, and whether the elastic member 8v is forgotten or erroneously assembled, whether the elastic member 8v is properly assembled, or the like can be checked.

In this example, the openings 42b and 42c for allowing the opposite end surfaces of the pair of roller elements 13a and 13b to be visually inspected also function as oil discharge holes. Therefore, only the end surfaces of the pair of roller elements 13a, 13b facing each other need be visually recognized, and an opening need not be provided in the cylindrical portion 18d of the connecting tube 14 d.

In this example, since the openings 42b and 42c are provided at a plurality of circumferentially equally spaced portions of the cylindrical portion 18d, the distance between the distal end surfaces of the pair of roller elements 13a and 13b can be measured at a plurality of circumferentially spaced portions after the sun roller 4, the pair of roller elements 13a and 13b, and the plurality of intermediate rollers 6 are disposed radially inward of the connecting tube 14 d. Therefore, the parallelism of the front end surfaces of the pair of roller elements 13a, 13b can be confirmed.

In this example, the structure in which the gap 55 is provided between the elastic member 8v and the roller element 13a on one axial side has been described, but the friction roller speed reducer of the present embodiment can also be applied to a structure in which the elastic member is sandwiched between the tip end surfaces of the pair of roller elements in an uncompressed or slightly compressed state in an initial state. In this case, the distance between the front end surfaces of the pair of roller elements in the initial state and the contact state between the front end surfaces of the pair of roller elements and the elastic member can be accurately regulated, and when the torque transmitted by the friction roller reducer increases, the force applied by the elastic member to the pair of roller elements can be set to a desired level. The configuration and operational effects of the other parts are the same as those of the first example of the first embodiment and the first example of the sixth embodiment.

In the present embodiment, the example in which the loading cam device 7 is used as the pressing device has been described, but in the case of implementing the present embodiment, a pump type pressing device using fluid pressure such as oil or air, or a pressing device including a driver such as an electric motor may be used as the pressing device for pressing the pair of roller elements in the direction in which the pair of roller elements are brought close to each other.

[ first example of seventh embodiment ]

Fig. 53 shows a first example of a seventh embodiment of the present invention. In the ninth example of the first embodiment to the first embodiment, the ring roller includes a pair of roller elements, and an elastic member is interposed between the pair of roller elements, but in the friction roller reducer 1f of the present example, the sun roller 4a includes a pair of roller elements 59a, 59b, and an elastic member 8w is interposed between the distal end surfaces of the pair of roller elements 59a, 59b. The friction roller reducer 1h of the present example includes an input shaft 2a, an output shaft 3a, a sun roller 4a, a ring roller 5d, a plurality of intermediate rollers 6, a loading cam device 7a, and an elastic member 8w.

The sun roller 4a includes a pair of roller elements 59a and 59b. The pair of roller elements 59a and 59b have inclined surface portions 60a and 60b on the outer peripheral surface, respectively, which are inclined in the radial direction in a direction approaching the intermediate roller 6, in other words, in a direction in which the outer diameter increases as the roller elements are separated from each other in the axial direction. That is, in this example, the inner diameter side rolling contact surface 11a is constituted by inclined surface portions 60a, 60b of the pair of roller elements 59a, 59b. In this example, the inclined surface portions 60a and 60b are formed of conical convex surfaces having a linear busbar shape.

The pair of roller elements 59a and 59b have flat surfaces 61 orthogonal to the respective central axes O on the end surfaces facing each other. In this example, the entire front end surfaces of the pair of roller elements 59a, 59b are constituted by the flat surface portion 61.

The sun roller 4a of the present example is configured by combining a pair of roller elements 59a and 59b so as to be capable of relative displacement in the axial direction via an input shaft 2a and a loading cam device 7a described below. The roller element 59a on one axial side (left side in fig. 53) of the pair of roller elements 59a, 59b is fitted to the axial intermediate portion of the input shaft 2a so as to be capable of relative displacement and relative rotation in the axial direction with respect to the input shaft 2 a. In contrast, the roller element 59b on the other side in the axial direction is fitted and fixed to the front end portion (the other side in the axial direction, the right side in fig. 53) of the input shaft 2a so as not to be able to perform relative displacement in the axial direction and relative rotation with respect to the input shaft 2 a.

The ring roller 5d has an outer diameter side rolling contact surface 12a on the inner peripheral surface, and is disposed coaxially with the sun roller 4a around the sun roller 4 a. In this example, the outer diameter side rolling contact surface 12a is constituted by a cylindrical surface whose inner diameter does not change in the axial direction. The ring roller 5d is connected to the output shaft 3a so as to rotate integrally with the output shaft 3 a.

The plurality of intermediate rollers 6 each have a rolling surface 21 on the outer peripheral surface that is in rolling contact with the inner diameter side rolling contact surface 11a and the outer diameter side rolling contact surface 12 a. The rolling surface 21 has: a pair of intermediate roll inclined portions 22 disposed at both axial side portions, each inclined in a direction in which the outer diameter decreases as the axial direction moves away from each other; and a connecting surface portion 23 disposed at the axial intermediate portion and connecting the pair of intermediate roll side inclined portions 22 to each other. In this example, the inclined surface portions 60a, 60b constituting the inner diameter side rolling contact surface 11a are in rolling contact with the intermediate roller side rolling contact portion 22 in the rolling surface 21, respectively, and the outer diameter side rolling contact surface 12a is in rolling contact with the connecting surface portion 23 in the rolling surface 21.

The intermediate roller 6 is supported so as to be rotatable (autorotative) about a rotation shaft 24 provided in a center portion and displaceable in a radial direction with respect to a fixed portion that does not rotate even when the housing or the like is in use. That is, the intermediate rollers 6 are each capable of rotating, but are prevented from rotating (revolving) about the central axis O of the input shaft 2 a.

The loading cam device 7a presses the pair of roller elements 59a, 59b constituting the sun roller 4a in a direction to bring the pair of roller elements 59a, 59b closer to each other. The loading cam device 7a includes a roller element 59a, a cam plate 27a, and a plurality of rolling elements 28a on one axial side.

The roller element 59a on one side in the axial direction has driven-side cam surfaces 32a in which the same number of concave portions and convex portions are alternately arranged in the circumferential direction on one side in the axial direction.

The cam plate 27a has drive-side cam surfaces 29a formed by alternately arranging the same number of concave portions and convex portions in the circumferential direction on the other side surface in the axial direction, and is fitted and fixed to one axial-side portion of the input shaft 2a so as not to be able to perform relative displacement and relative rotation in the axial direction with respect to the input shaft 2a.

The plurality of rolling elements 28a are disposed between the driven-side cam surface 32a of the roller element 59a on one axial side and the driving-side cam surface 29a of the cam plate 27a so as to be capable of rolling.

The elastic member 8w is disposed between the flat surface portions 61 of the pair of roller elements 59a, 59 b. In this example, the elastic member 8w is constituted by a single piece of belleville spring 36. In an initial state before the pressing force is exerted by the loading cam device 7a, the elastic member 8b is sandwiched between the flat surface portions 61 of the pair of roller elements 59a and 59b in a state of being elastically compressed. Therefore, the elastic member 8w applies a force in a direction of separating the pair of roller elements 59a and 59b from each other even in the initial state.

In the operation of the friction roller reducer 1f of the present example, the input shaft 2a is driven by the drive source to rotate, so that the sun roller 4a is driven to rotate. When the sun roller 4a rotates, the intermediate roller 6 rotates due to rolling contact between (the pair of inclined surface portions 60a and 60b of) the inner diameter side rolling contact surface 11a of the sun roller 4a and (the pair of intermediate roller side rolling contact portions 22 of) the rolling surface 21 of the intermediate roller 6. When the intermediate roller 6 rotates, the ring roller 5a rotates around the central axis O of the input shaft 2a due to rolling contact between (the connecting surface 23 of) the rolling surface 21 of the intermediate roller 6 and the outer diameter side rolling contact surface 12a of the ring roller 5a, and the rotation of the ring roller 5d is taken out from the output shaft 3 a.

In the friction roller reducer 1f of the present example, when the cam plate 27a rotates with the rotation of the input shaft 2a, the amount of jump-up of the rolling element 28a of the loading cam device 7a from the bottom of the concave portion of the driving side cam surface 29a and the amount of jump-up from the bottom of the concave portion of the driven side cam surface 32a increase. As a result, the axial dimension of the loading cam device 7a increases, the pair of roller elements 59a, 59b are pressed in the directions approaching each other, and the roller element 59a on one axial side is driven to rotate. That is, the roller element 59a on the one axial side is pressed to the other axial side, and at the same time, the cam plate 27a is pressed to the one axial side, whereby the roller element 59b on the other axial side is pulled to the one axial side via the input shaft 2 a.

When the pair of roller elements 59a and 59b are pressed in the directions approaching each other, the outer diameter of the portion of the inclined surface portions 60a and 60b constituting the inner diameter side rolling contact surface 11a that is in rolling contact with the pair of intermediate roller side rolling portions 22 constituting the rolling surface 21 increases, and the surface pressure of the traction portion (rolling contact portion) between the inner diameter side rolling contact surface 11a and the rolling surface 21 increases. When the intermediate roller 6 is pressed radially outward with this surface pressure rise, the surface pressure of the traction portion between the connecting surface portion 23 of the rolling surface 21 and the outer diameter side rolling contact surface 12a also rises. As a result, excessive slip is not generated in each traction portion, and the torque input from the input shaft 2a to the sun roller 4a is transmitted to the ring roller 5d via the intermediate roller 6.

In the friction roller reducer 1f of the present example, the elastic member 8w is sandwiched between the flat surface portions 61 of the pair of roller elements 59a and 59b, and the elastic member 8w applies a force in a direction of separating the pair of roller elements 59a and 59b from each other. Therefore, the amount of increase in the surface pressure of the traction portion between the rolling surface 21 and the inner-diameter-side rolling contact surface 11a and the outer-diameter-side rolling contact surface 12a due to the pressing of the pair of roller elements 59a, 59b by the loading cam device 7a in the direction to bring the pair of roller elements 59a, 59b closer to each other is reduced by the amount corresponding to the force in the direction to separate the pair of roller elements 59a, 59b applied by the elastic member 8 w. In other words, the magnitude of the normal force acting on each traction portion is reduced by an amount corresponding to the force applied to the pair of roller elements 59a and 59b by the elastic member 8w, and the operation traction coefficient (tangential force/normal force corresponding to the torque transmitted from the sun roller 4a, the ring roller 5d, and the intermediate roller 6) indicating the actual operation state is increased.

In the friction roller reducer 1f of the present example as described above, as in the friction roller reducer 1 of the first example of the first embodiment, the running traction coefficient can be adjusted to an appropriate level regardless of the magnitude of the transmitted torque, and the transmission efficiency of the friction roller reducer 1f can be ensured satisfactorily. In addition, at the time of high torque transmission, the running traction coefficient can be increased, and an acceleration increase in pressing force due to the occurrence of skew of the intermediate roller 6 can be effectively prevented.

In this example, the ring roller 5d is connected to the output shaft 3a so as to rotate integrally with the output shaft 3a, and the plurality of intermediate rollers 6 are supported so as not to be rotatable (revolvable) about the central axis O of the input shaft 2 a. However, in the case of carrying out the present invention, in the case where the sun roller is constituted by a pair of roller elements, the ring roller may be supported so as not to rotate, and the revolution motion of the intermediate roller may be taken out from the output shaft. The other parts are similar in structure and operation to those of the first example of the first embodiment.

The first to seventh embodiments of the first embodiment described above can be appropriately combined and implemented within a range where no contradiction occurs.

Description of symbols

1. 1a, 1b, 1c, 1d, 1e, 1 f-friction roller speed reducers, 2 a-input shafts, 3 a-output shafts, 4 a-sun rollers, 5a, 5b, 5c, 5 d-ring rollers, 6 z-intermediate rollers, 7-loading cam means, 8a, 8b, 8c, 8d, 8e, 8g, 8h, 8i, 8j, 8k, 8l, 8m, 8n, 8o, 8p, 8q, 8r, 8s, 8t, 8u, 8v, 8w, 8 z-elastic members, 9-male spline section, 10-flange section, 11-inner diameter side rolling surface, 12-outer diameter side rolling surface, 13a, 13 b-roller elements, 14a, 14b, 14c, 14 d-connecting cylinders, 15a, 15 b-inclined surface section, 16-flat surface section, 17-element side engaging concave-convex section, 18a, 18b, 18c, 18 d-cylindrical section, 19 a-side plate section, 20-cylinder side engaging concave-convex section, 21a, 21b, 21 z-rolling surface, 22, 22 a-intermediate roll side inclined surfaces, 23 a-connecting surfaces, 24-rotation shafts, 25-brackets, 26-radial rolling bearings, 27 a-cam plates, 28 a-rolling bodies, 29 a-drive side cam surfaces, 30-cylindrical portion, 31-side plate portion, 32 a-driven side cam surface, 33-thrust needle bearing, 34-thrust race, 35 a-retainer ring, 36a, 36b, 36c, 36 d-belleville spring, 37-torsion coil spring, 38-holding recess, 39-retainer, 40-holding hole, 41-gap, 42a, 42b, 42 c-opening, 43-support member, 44-oil supply, 45-angular ball bearing, 46a, 46b, 46c, 46d, 46 e-oil discharge passage, 47 a-cutout, 48-shim plate, 49-groove, 50-tooth lock washer, 51-cutout, 52-groove, 53-groove, 54-through hole, 55-gap, 56-concave, 57-convex, 58a, 58 b-oil discharge hole, 59a, 59 b-roller element, 60a, 60 b-inclined surface, 61-flat surface, 100-friction roller speed reducer, 101-input shaft, 102-output shaft, 103-sun roller, 104-ring roller, 105-intermediate roller, 106-loading cam device, 107-flange, 108-inner diameter side rolling contact surface, 109-outer diameter side rolling contact surface, 110a, 110 b-roller element, 111-connecting cylinder, 112a, 112 b-inclined surface, 113-engaging concave-convex portion, 114-retainer ring, 115-rolling surface, 116-bracket, 117-cam disc, 118-rolling body, 119-driving side cam surface, 120-cylinder portion, 121-side plate portion, 122-convex portion, 123-driven side cam surface, 124-angular bearing.

Claims (24)

1. A friction roller speed reducer is characterized by comprising:

a sun roller;

a ring roller coaxially disposed around the sun roller; and

a plurality of intermediate rollers having rolling surfaces on the outer peripheral surfaces thereof in rolling contact with the sun roller and the ring roller,

one of the sun roller and the ring roller has a pair of roller elements supported so as to be axially relatively displaceable, the pair of roller elements including inclined surface portions which are inclined in a radial direction so as to approach the intermediate roller as the roller elements are axially separated from each other on a peripheral surface in rolling contact with the rolling surface,

the friction roller speed reducer includes:

a pressing device that presses the pair of roller elements in a direction in which the pair of roller elements approach each other; and

and an elastic member which is disposed between the pair of roller elements and which elastically biases the pair of roller elements in a direction away from the rolling surface of the intermediate roller.

2. The friction roller speed reducer according to claim 1, wherein,

the pressing device is composed of a loading cam device.

3. A friction roller speed reducer according to claim 1 or 2, characterized in that,

The rolling surface has: a pair of intermediate roller side inclined surfaces which are disposed at both axial side portions, incline in a direction in which the outer diameter becomes smaller as the axial direction is directed to the direction of mutual separation, and are in rolling contact with the inclined surfaces; and a connecting surface portion which is disposed in the axial intermediate portion, has an outer diameter which does not change in the axial direction or has a generatrix with a radius of curvature larger than that of the generatrix of the intermediate roller-side inclined portion, and is in rolling contact with the other roller of the sun roller and the ring roller.

4. A friction roller speed reducer according to claim 3, wherein,

the pair of intermediate roll inclined portions have a circular arc or linear busbar shape.

5. A friction roller speed reducer according to any one of claims 1 to 4,

in an initial state before the pressing device exerts the pressing force, a gap is provided between the elastic member and at least one of the pair of roller elements.

6. A friction roller speed reducer according to any one of claims 1 to 4,

the elastic component is composed of one or more belleville springs,

the thickness of the belleville spring is set to t and the total deflection is set to h ₀ In the case of (h) ₀ And/t is 1.0 or less.

7. A friction roller speed reducer according to any one of claims 1 to 6,

the ring roller includes the pair of roller elements, and the pair of roller elements includes the inclined surface portion that is inclined in a direction that decreases in inner diameter as the pair of roller elements are separated from each other in the axial direction.

8. The friction roller speed reducer according to claim 7, wherein,

the elastic member has two belleville springs each having a substantially V-shaped cross section and combined so as to have an opening on an inner diameter side.

9. The friction roller speed reducer according to claim 7, wherein,

the elastic member has two belleville springs each having a substantially V-shaped cross section and combined so as to have an opening on the outer diameter side.

10. A friction roller speed reducer according to any one of claims 7 to 9,

the ring roller has a coupling cylinder that supports the pair of roller elements so as to be capable of relative displacement in the axial direction and so as not to be capable of relative rotation.

11. The friction roller reducer according to claim 10, wherein,

the connecting tube has an opening portion that opens on an inner peripheral surface and an outer peripheral surface.

12. The friction roller reducer according to claim 11, wherein,

The opening has a size capable of visually observing end surfaces of the pair of roller elements facing each other from the radial outside of the connecting tube.

13. The friction roller reducer according to claim 12, wherein,

the opening has a size that enables the elastic member to visually contact the pair of roller elements from the radially outer side of the connecting tube.

14. The friction roller reducer according to any one of claims 11 to 13, characterized in that,

the opening portion forms an oil drain hole.

15. The friction roller reducer according to any one of claims 11 to 14, characterized in that,

the connecting tube has the openings at a plurality of circumferentially equally spaced locations.

16. A friction roller speed reducer according to any one of claims 7 to 15, characterized in that,

the roller device is provided with an oil discharge path which includes the elastic member and communicates the inside with the outside in the radial direction of the space between the pair of roller elements.

17. The friction roller reducer according to claim 16, wherein,

the elastic member is formed of one or more belleville springs.

18. The friction roller reducer according to claim 17, wherein,

The elastic member has a cutout opening at an outer peripheral edge and/or an inner peripheral edge, or has a through hole penetrating a radially intermediate portion.

19. The friction roller reducer according to claim 17, wherein,

comprises a backing plate sandwiched between at least one of the pair of roller elements and the elastic member,

the pad has grooves or ridges on the axial side surface throughout the radial direction.

20. The friction roller reducer according to claim 17, wherein,

the pair of roller elements is provided with a tooth-shaped lock washer clamped between at least one roller element and the elastic member.

21. The friction roller reducer according to claim 17, wherein,

at least one of the pair of roller elements has a groove in a distal end surface in a radial direction.

22. The friction roller reducer according to claim 16, wherein,

the elastic member is formed of a wave washer.

23. The friction roller reducer according to claim 16, wherein,

the elastic member is constituted by a torsion coil spring.

24. The friction roller reducer according to claim 17, wherein,

Comprises a retainer having a plurality of retaining holes penetrating in the axial direction at a plurality of circumferential positions and disposed between the pair of roller elements,

the torsion coil springs are held in the holding holes, respectively.