WO2020004037A1 - Reducer and power steering device - Google Patents

Reducer and power steering device Download PDF

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Publication number
WO2020004037A1
WO2020004037A1 PCT/JP2019/023278 JP2019023278W WO2020004037A1 WO 2020004037 A1 WO2020004037 A1 WO 2020004037A1 JP 2019023278 W JP2019023278 W JP 2019023278W WO 2020004037 A1 WO2020004037 A1 WO 2020004037A1
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WO
WIPO (PCT)
Prior art keywords
bearing
raceway groove
speed reducer
drive gear
outer ring
Prior art date
Application number
PCT/JP2019/023278
Other languages
French (fr)
Japanese (ja)
Inventor
貴也 柳生
Original Assignee
Ｋｙｂ株式会社
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Filing date
Publication date
Application filed by Ｋｙｂ株式会社 filed Critical Ｋｙｂ株式会社
Publication of WO2020004037A1 publication Critical patent/WO2020004037A1/en

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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B62—LAND VEHICLES FOR TRAVELLING OTHERWISE THAN ON RAILS
    • B62D—MOTOR VEHICLES; TRAILERS
    • B62D5/00—Power-assisted or power-driven steering
    • B62D5/04—Power-assisted or power-driven steering electrical, e.g. using an electric servo-motor connected to, or forming part of, the steering gear
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16C—SHAFTS; FLEXIBLE SHAFTS; ELEMENTS OR CRANKSHAFT MECHANISMS; ROTARY BODIES OTHER THAN GEARING ELEMENTS; BEARINGS
    • F16C19/00—Bearings with rolling contact, for exclusively rotary movement
    • F16C19/02—Bearings with rolling contact, for exclusively rotary movement with bearing balls essentially of the same size in one or more circular rows
    • F16C19/04—Bearings with rolling contact, for exclusively rotary movement with bearing balls essentially of the same size in one or more circular rows for radial load mainly
    • F16C19/06—Bearings with rolling contact, for exclusively rotary movement with bearing balls essentially of the same size in one or more circular rows for radial load mainly with a single row or balls
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16C—SHAFTS; FLEXIBLE SHAFTS; ELEMENTS OR CRANKSHAFT MECHANISMS; ROTARY BODIES OTHER THAN GEARING ELEMENTS; BEARINGS
    • F16C25/00—Bearings for exclusively rotary movement adjustable for wear or play
    • F16C25/06—Ball or roller bearings
    • F16C25/08—Ball or roller bearings self-adjusting
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16H—GEARING
    • F16H1/00—Toothed gearings for conveying rotary motion
    • F16H1/02—Toothed gearings for conveying rotary motion without gears having orbital motion
    • F16H1/04—Toothed gearings for conveying rotary motion without gears having orbital motion involving only two intermeshing members
    • F16H1/12—Toothed gearings for conveying rotary motion without gears having orbital motion involving only two intermeshing members with non-parallel axes
    • F16H1/16—Toothed gearings for conveying rotary motion without gears having orbital motion involving only two intermeshing members with non-parallel axes comprising worm and worm-wheel
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16H—GEARING
    • F16H57/00—General details of gearing
    • F16H57/02—Gearboxes; Mounting gearing therein
    • F16H57/021—Shaft support structures, e.g. partition walls, bearing eyes, casing walls or covers with bearings
    • F16H57/022—Adjustment of gear shafts or bearings

Definitions

  • the present invention relates to a speed reducer and a power steering device.
  • the worm speed reducer includes a worm shaft that is rotationally driven by a drive source such as an electric motor, and a worm wheel that meshes with the worm shaft. Both ends of the worm shaft are rotatably supported by bearings.
  • the base end of the worm shaft is swingably connected to the rotating shaft of the electric motor, and the distal end of the worm shaft is urged toward the worm wheel by the urging member.
  • the bearing supporting the base end of the worm shaft is provided with an internal clearance so that the inner ring can swing with respect to the outer ring.
  • the bearing is provided with the internal clearance, when an axial force acts on the worm shaft, the inner ring moves slightly in the axial direction together with the worm shaft, so that the rolling element (ball) is moved to the outer ring.
  • noise collision sound
  • the present invention aims to reduce the noise of the speed reducer.
  • a speed reducer including a drive gear shaft connected to a drive source, and a driven gear meshing with the drive gear shaft, wherein a base end side of the drive gear shaft is rotatable.
  • a first bearing for supporting, a second bearing for rotatably supporting the distal end side of the drive gear shaft, and an urging member for urging the drive gear shaft toward the driven gear via the second bearing.
  • the first bearing comprises: an inner ring having an inner raceway groove; an outer ring having an outer raceway groove; and a plurality of rolling elements disposed between the inner raceway groove and the outer raceway groove.
  • a distance between the inner raceway groove and the outer raceway groove in a first direction which is a direction in which the drive gear shaft swings, and in a second direction orthogonal to each of the axial directions of the drive gear shaft, The distance between the inner raceway groove and the outer raceway groove in the first direction; It is also small.
  • a speed reducer including a drive gear shaft connected to a drive source, and a driven gear meshing with the drive gear shaft, wherein a base end side of the drive gear shaft is rotatable.
  • a second bearing rotatably supporting the distal end side of the drive gear shaft, and a bias for biasing the drive gear shaft toward the driven gear via the second bearing.
  • the pressing portion sets a direction in which the drive gear shaft swings as a first direction, and includes a first direction and an axial direction of the drive gear shaft.
  • a direction orthogonal to each is defined as a second direction, the second direction with respect to the first bearing Pressure, the to be larger than the pressing force of the first direction relative to the first bearing, to press the outer ring of the first bearing.
  • a power steering device including the speed reducer and an electric motor serving as the drive source, wherein the driven gear is provided on a rack shaft that steers a wheel.
  • the speed reducer is provided on an output shaft that transmits a rotational force of a motor, and reduces the rotation of the drive gear shaft and transmits the rotation to the driven gear.
  • FIG. 1 is a configuration diagram of a power steering device including a speed reducer according to a first embodiment of the present invention.
  • FIG. 2 is a cross-sectional view of a power steering device including the speed reducer according to the first embodiment of the present invention.
  • FIG. 3A is a schematic cross-sectional view of the bearing, showing a state where the inner ring is not inclined with respect to the outer ring.
  • FIG. 3B is a schematic cross-sectional view of the bearing, showing a state where the inner ring is inclined with respect to the outer ring.
  • FIG. 4 is a perspective view of the speed reducer with a gear case partially cut away.
  • FIG. 5 is a schematic sectional view of the speed reducer taken along line VV in FIG. FIG.
  • FIG. 6 is a schematic cross-sectional view of the inner ring and the outer ring of the first bearing along the line VI-VI in FIGS. 7 and 8.
  • FIG. 7 is a schematic sectional view of the first bearing taken along line VII-VII in FIG.
  • FIG. 8 is a schematic sectional view of the first bearing taken along line VIII-VIII in FIG.
  • FIG. 9 is a schematic sectional view of a speed reducer according to a second embodiment of the present invention.
  • FIG. 10 is a diagram illustrating a pressing ring used in a speed reducer according to a second embodiment of the present invention.
  • FIG. 11 is a diagram illustrating a pressing ring deformed by press-fitting a bearing.
  • FIG. 12 is a schematic cross-sectional view illustrating a pressing portion provided in a housing hole of a speed reducer according to a modification.
  • a power steering device including a speed reducer according to a first embodiment of the present invention will be described with reference to the drawings.
  • a power steering device is a device that is mounted on a vehicle and assists a steering force applied by a driver to a steering wheel.
  • the power steering device 10 includes a speed reducer 100 and an electric motor 7 as a drive source.
  • the speed reducer 100 is connected to an output shaft 7 a of the electric motor 7 and meshes with a worm shaft 2 as a drive gear shaft that rotates with the driving of the electric motor 7, and a worm 2 a as a drive gear formed on the worm shaft 2.
  • the worm wheel 1 includes a worm wheel 1 as a driven gear, a gear case 3 that is a case that houses the worm shaft 2 and the worm wheel 1, and a shaft support structure 101 that supports the worm shaft 2.
  • the worm shaft 2 and the output shaft 7a of the electric motor 7 are connected by a shaft connecting device 19 that allows a shaft deviation.
  • a steering shaft 20 is connected to the steering wheel 16, and the steering shaft 20 rotates with the rotation of the steering wheel 16.
  • the steering shaft 20 includes an input shaft 21 linked to the steering wheel 16, an output shaft 22 linked to the rack shaft 8, and a torsion bar 23 connecting the input shaft 21 and the output shaft 22.
  • the worm wheel 1 is provided on the output shaft 22.
  • the power steering device 10 includes a torque sensor 24 that detects a steering torque acting on a torsion bar 23 by a relative rotation between an input shaft 21 and an output shaft 22 caused by a driver's steering operation, and a steering detected by the torque sensor 24.
  • a controller that controls the driving of the electric motor based on the torque.
  • the torque output from the electric motor 7 is transmitted from the worm shaft 2 to the worm wheel 1 and applied to the output shaft 22 as assist torque.
  • the power steering device 10 assists the driver in steering by controlling the driving of the electric motor 7 by the controller 25 based on the detection result of the torque sensor 24.
  • the speed reducer 100 reduces the rotation of the worm shaft 2 and transmits the rotation to the worm wheel 1.
  • the output shaft 22 provided with the worm wheel 1 transmits the torque of the electric motor 7 to the rack shaft 8 that steers the wheels 6.
  • the worm shaft 2 is housed in a metal gear case 3, and the electric motor 7 is attached to the gear case 3.
  • the worm 2a is formed with teeth 2e that mesh with the teeth 1a of the worm wheel 1.
  • An opening 3c is formed in the gear case 3 at a position corresponding to the tooth 2e, and the tooth 2e of the worm 2a and the tooth 1a of the worm wheel 1 mesh with each other through the opening 3c.
  • the shaft support structure 101 of the speed reducer 100 includes a first bearing 4 that rotatably supports the base end side (the electric motor 7 side) of the worm shaft 2 and a distal end side (the side opposite to the electric motor 7 side) of the worm shaft 2. ), And a coil spring 12 as an urging member for urging the worm shaft 2 toward the worm wheel 1 via the second bearing 11.
  • the worm shaft 2 is rotatably supported in the gear case 3 by a pair of bearings (a first bearing 4 and a second bearing 11).
  • the axial direction (center axis direction) of the worm shaft 2 is also simply referred to as the axial direction (D3).
  • the first bearing 4 is a deep groove ball bearing in which a ball (ball) 143 as a rolling element is interposed between the annular outer ring 141 and the inner ring 142.
  • the first bearing 4 is housed in a housing hole 130 provided in the gear case 3.
  • the outer ring 141 of the first bearing 4 is held in the axial direction (D3) between the stepped portion 3a formed in the gear case 3 and the lock nut 5 fastened in the gear case 3.
  • the inner ring 142 of the first bearing 4 is fixed by being pressed into the worm shaft 2.
  • the inner ring 142 is sandwiched in the axial direction (D3) between the step portion 2b of the worm shaft 2 and the worm-side joint 9 of the shaft coupler 19 that is press-fitted into the end of the worm shaft 2.
  • the first bearing 4 has an internal clearance 144 (see FIG. 7) for allowing the worm shaft 2 to swing toward the worm wheel 1.
  • a first direction in which the worm shaft 2 swings about the first bearing 4 is referred to as a swing direction (D1). Details of the first bearing 4 will be described later.
  • the second bearing 11 is a deep groove ball bearing in which a ball (ball) as a rolling element is interposed between an annular outer ring and an inner ring.
  • the second bearing 11 is housed at the bottom of the gear case 3.
  • a step 2c formed near the tip of the worm shaft 2 is locked to the inner ring of the second bearing 11.
  • An end surface 17 a is formed on the outer peripheral surface of the gear case 3 so as to protrude from a flat flange portion 17.
  • a through hole 13 is formed in the flange portion 17 and opens toward the outer peripheral surface of the second bearing 11. The opening of the through hole 13 that opens to the end face 17 a of the flange 17 is closed by the plug 14.
  • the coil spring 12 is housed in a state where the coil spring 12 is compressed between the distal end surface of the plug 14 and the outer peripheral surface of the second bearing 11 in the through hole 13.
  • the coil spring 12 urges the second bearing 11 in a direction in which a gap between the teeth 2e of the worm 2a and the teeth 1a of the worm wheel 1 is reduced, that is, in a direction in which the worm 2a meshes with the worm wheel 1.
  • the inner peripheral surface 3b surrounding the outer peripheral surface of the second bearing 11 in the gear case 3 has a pair of parallel flat portions so that the second bearing 11 can move toward the worm wheel 1 by the urging force of the coil spring 12. It is formed in a long hole shape.
  • the inner peripheral surface 3b may have any shape as long as the second bearing 11 can move inside the inner peripheral surface 3b.
  • the inner peripheral surface 3b may have a round hole shape whose inner diameter is larger than the outer diameter of the second bearing 11, and there is no need to form a pair of parallel flat portions.
  • the second bearing 11 is urged toward the worm wheel 1 by the urging force of the coil spring 12, and the backlash between the worm 2a and the worm wheel 1 is increased. There is no (gap). In this state, the worm shaft 2 is tilted about the first bearing 4 as a fulcrum by the urging force of the coil spring 12.
  • the first bearing 4 is provided with an internal gap 144 so that the inner ring 142 fixed to the worm shaft 2 can swing with respect to the outer ring 141 fixed to the gear case 3.
  • the internal clearance 144 is provided over the entire circumference of the first bearing 4, when a force in the axial direction (D3) acts on the worm shaft 2, the inner ring 142 together with the worm shaft 2 slightly moves in the axial direction (D3). May move. Therefore, for example, when a force in the axial direction (D3) acts on the worm shaft 2 from the electric motor 7 at the time of reverse steering, the ball 143 collides with the outer ring 141 or the inner ring 142, and noise (collision sound) is generated. There is a risk. Also, when a force in the axial direction (D3) acts on the worm shaft 2 from the worm wheel 1 via the wheels 6, the rack shaft 8, the output shaft 22, and the like from the road surface, noise (collision noise) may similarly be generated. There is also.
  • the inside of the first bearing 4 is set.
  • the size of the gap 144 is made different depending on the position in the circumferential direction.
  • an internal gap 144 having a predetermined length X (> 0) is secured, and each is orthogonal to the swing direction (D1) and the axial direction (D3) of the worm shaft 2.
  • the orthogonal direction (D2) which is the second direction, the internal gap 144 is set to 0 or almost 0.
  • FIG. 4 is a perspective view of the speed reducer 100 with the gear case 3 partially cut away. 4, illustration of the worm wheel 1 is omitted.
  • FIG. 5 is a schematic cross-sectional view of the speed reducer 100 along the line VV in FIG.
  • the shaft support structure 101 of the speed reducer 100 further includes a bolt 150 as a pressing portion that presses the outer periphery of the outer ring 141 of the first bearing 4 in the orthogonal direction (D2).
  • the gear case 3 has an insertion hole 133 through which the bolt 150 is inserted.
  • the insertion hole 133 is a through hole that penetrates in the orthogonal direction (D2), and a female screw that is screwed to a male screw formed on the outer periphery of the shaft of the bolt 150 is formed on the inner peripheral surface. Therefore, by rotating the bolt 150 from outside the gear case 3 using a tool or the like, the bolt 150 can be moved in the orthogonal direction (D2) along the insertion hole 133.
  • the bottom 131 that faces the insertion hole 133 is a support that supports the first bearing 4. That is, the housing hole 130 of the gear case 3 forms a part of the shaft support structure 101, and the bottom 131 of the housing hole 130 functions as a pressing portion that presses the outer circumference of the outer ring 141 of the first bearing 4 in the orthogonal direction (D2). .
  • the outer ring 141 of the first bearing 4 is sandwiched in the orthogonal direction (D2) between the bolt 150 as a pressing portion and the bottom 131 as a pressing portion formed in the housing hole 130.
  • the outer ring 141 of the first bearing 4 has a circular outer and inner circumference before being assembled to the gear case 3.
  • the outer ring 141 of the first bearing 4 is compressed in the orthogonal direction (D2) and expands in the swing direction (D1). Deform to.
  • the outer ring 141 of the first bearing 4 is assembled to the gear case 3 and, after the bolt 150 is screwed by a predetermined amount, the outer circumference and the inner circumference each have an elliptical shape. Become.
  • the bolt 150 is arranged such that the central axis of the worm shaft 2 is located on an extension of the central axis. For this reason, the bolt 150 presses the outer peripheral surface of the outer ring 141 toward the central axis of the worm shaft 2.
  • the tip surface 151 of the shaft of the bolt 150 is formed so as not to prevent the outer ring 141 from being deformed into an elliptical shape when the outer ring 141 is pressed by the bolt 150.
  • the tip surface 151 of the shaft of the bolt 150 is formed in a flat shape.
  • the inner peripheral surface of the housing hole 130 is formed so as not to hinder the outer ring 141 from being deformed into an elliptical shape when the outer ring 141 is pressed by the bolt 150.
  • the radius of curvature of the inner peripheral surface of the bottom portion 131 of the housing hole 130 is formed to be larger than the radius of curvature of a portion of the outer ring 141 deformed into an elliptical shape that comes into contact with the bottom portion 131.
  • the outer ring 141 deformed into an elliptical shape may have both ends in the swing direction (D1) in contact with the inner peripheral surface of the housing hole 130, or may not be in contact as illustrated.
  • At least the first bearing 4 is set so that the pressing force acting on the first bearing 4 in the orthogonal direction (D2) is greater than the pressing force acting on the first bearing 4 in the swing direction (D1).
  • the outer ring 141 may be configured to be pressed.
  • the diameter of the shaft portion of the bolt 150 is set to, for example, ⁇ or more of the width (length in the axial direction (D3)) of the outer ring 141 in order to secure a pressing range against the outer peripheral surface of the outer ring 141.
  • the diameter of the bolt 150 may be set to be smaller than the width of the outer ring 141. preferable. Further, by setting the diameter of the bolt 150 to be smaller than the width of the outer ring 141, the degree of freedom in layout is also improved.
  • FIG. 6 is a schematic cross-sectional view of the inner ring 142 and the outer ring 141 of the first bearing 4 along the line VI-VI in FIGS. 7 and 8. 6, illustration of the ball 143 is omitted.
  • FIG. 7 is a schematic sectional view of the first bearing 4 along the line VII-VII in FIG. 6, and FIG. 8 is a schematic sectional view of the first bearing 4 along the line VIII-VIII in FIG. 6 to 8, illustration of a retainer that holds the ball 143 is omitted.
  • the inner diameter of the inner ring 142 of the first bearing 4 is shown smaller than those shown in FIGS. In FIG. 7, the internal gap 144 is exaggerated and enlarged.
  • the first bearing 4 is disposed between the inner race 142 having the inner race groove 142a, the outer race 141 having the outer race groove 141a, and the inner race groove 142a and the outer race groove 141a.
  • the outer ring 141 is pressed in the orthogonal direction (D2) by the bolt 150 and is held in the accommodation hole 130 in a state of being deformed into an elliptical shape.
  • the outer raceway groove 141a that forms the inner peripheral surface of the outer ring 141 has a major axis length of 2 ⁇ La and a minor axis length of 2 ⁇ L in a cross section orthogonal to the axial direction (D3) of the worm shaft 2. It has an elliptical shape of Lb (La> Lb).
  • the inner raceway groove 142a which is the outer peripheral surface of the inner ring 142, has a circular shape with a diameter Do.
  • the distance L2 between the inner raceway groove 142a and the outer raceway groove 141a becomes larger than before the deformation. Therefore, the internal gap 144 in the swing direction (D1) can be made larger than before the deformation.
  • the length X of the internal gap 144 in the swing direction (D1) allows the worm shaft 2 to swing in the swing direction (D1), and effectively causes the backlash between the worm 2a and the worm wheel 1.
  • (Gap) is set to a length that can be reduced.
  • the distance L1 is set to be equal to or slightly longer than the outer diameter of the ball 143 so that the length of the internal gap 144 in the orthogonal direction (D2) is zero or almost zero. Since the distance L1 and the distance L2 are set as described above, the length of the internal gap 144 in the orthogonal direction (D2) is smaller than the length X of the internal gap 144 in the swing direction (D1).
  • the bolt 150 is provided movably in the orthogonal direction (D2) in the insertion hole 133. Further, the first bearing 4 is configured such that the distance L1 between the inner raceway groove 142a and the outer raceway groove 141a in the orthogonal direction (D2) can be adjusted according to the screwing amount of the bolt 150. Therefore, the internal clearance 144 of the first bearing 4 in the orthogonal direction (D2) can be easily adjusted by the screwing amount of the bolt 150.
  • the length of the internal clearance 144 of the first bearing 4 in the orthogonal direction (D2) is determined by the distance from the receiving seat of the bolt 150 formed in the gear case 3 to the top surface of the head of the bolt 150 or the worm shaft 2 Can be managed by measuring the amount of rocking when a predetermined load is applied to the. As shown in FIG. 5, a shim 156 having a predetermined thickness may be interposed between the head of the bolt 150 and a receiving seat formed on the gear case 3 so as to obtain a predetermined swing amount. Good.
  • the outer raceway groove 141a of the first bearing 4 assembled to the power steering device 10 according to the present embodiment is orthogonal to the swing direction (D1) and the axial direction (D3) of the worm shaft 2 (D3).
  • the ellipse is formed so that the distance L1 between the inner raceway groove 142a and the outer raceway groove 141a in D2) is smaller than the distance L2 between the inner raceway groove 142a and the outer raceway groove 141a in the swing direction (D1). It is shaped. For this reason, while securing the internal clearance 144 of the first bearing 4 in the swing direction (D1), the internal clearance 144 of the first bearing 4 in the orthogonal direction (D2) is larger than the internal clearance 144 in the swing direction (D1). Can be smaller.
  • the outer race 141 of the first bearing 4 is held in a state of being pressed in the orthogonal direction (D2) by the bolts 150 and the bottom 131 of the receiving hole 130, so that the inner raceway groove 142a in the orthogonal direction (D2)
  • the distance L1 between the outer raceway groove 141a and the outer raceway groove 141a is deformed to be smaller than the distance L2 between the inner raceway groove 142a and the outer raceway groove 141a in the swing direction (D1).
  • the outer ring 141 is pressed by the bolt 150 and deformed into an elliptical shape, so that the internal clearance 144 of the first bearing 4 in the orthogonal direction (D2) can be easily reduced.
  • the manufacturing cost of the first bearing 4 can be reduced. Further, since a standard deep groove ball bearing can be used as the first bearing 4, the first bearing 4 can be easily obtained. Therefore, the cost of the power steering device 10 can be reduced.
  • the speed reducer 200 includes an annular pressing ring 250 as a pressing portion instead of the bolt 150 described in the first embodiment.
  • the gear case 203 of the speed reducer 200 is formed with a housing hole 230 for housing the first bearing 4.
  • the outer ring 141 of the first bearing 4 is held in the axial direction (D3) between the stepped portion 3a formed in the gear case 203 and the lock nut 5 fastened in the gear case 203.
  • the inner race 142 is sandwiched in the axial direction (D3) between the stepped portion 2b of the worm shaft 2 and the worm-side joint 9 (see FIG. 2) of the shaft coupler 19 which is press-fitted into the end of the worm shaft 2.
  • the housing hole 230 has a small diameter portion 230a having an inner diameter slightly larger than the outer diameter of the outer ring 141 of the first bearing 4, and a large diameter portion 230b having an inner diameter larger than the small diameter portion 230a.
  • the pressing ring 250 is loosely fitted to the large diameter portion 230b.
  • the pressing ring 250 is an annular member into which the outer ring 141 of the first bearing 4 is press-fitted.
  • the pressing ring 250 is provided with low rigidity portions 251 having lower rigidity than both ends 250b in the orthogonal direction (D2) at both ends 250a in the swinging direction (D1).
  • the low-rigidity portion 251 is formed such that the width in the radial direction is smaller than the width in the radial direction in another portion (for example, both ends 250b in the orthogonal direction (D2)). That is, the low-rigidity portion 251 is a thin portion whose thickness (radial width) is smaller than the thickness (radial width) of both ends 250b in the orthogonal direction (D2).
  • the low-rigidity portion 251 may be any portion that has lower rigidity than other portions. For this reason, even if it has the same thickness (radial width) as the other portions, the low-rigidity portion may be formed by providing a plurality of grooves or through holes.
  • the pressing ring may be formed by joining both ends of a pair of semi-arc members with members having a lower elastic modulus than the semi-arc members.
  • the connecting member that connects the semicircular arc-shaped members serves as a low rigidity portion.
  • the low-rigidity portion 251 can adopt various forms.
  • the low-rigidity portion 251 when the low-rigidity portion 251 is a thin portion having a smaller thickness than other portions, the low-rigidity portion 251 has a low rigidity. Since the rigid portion 251 can be easily formed, the manufacturing cost of the speed reducer 200 can be reduced.
  • the low-rigidity portion 251 is formed by forming a pair of flat rectangular surfaces on the outer periphery of the annular ring member.
  • the outer flat surfaces of the pair of low rigidity portions 251 are formed parallel to each other.
  • the interval (two-plane width) in the swing direction (D1) between the outer flat surfaces of the pair of low-rigidity portions 251 is smaller than the outer diameter of the pressing ring 250.
  • the inner diameter of the pressing ring 250 is slightly smaller than the outer diameter of the outer ring 141 of the first bearing 4.
  • the pressing ring 250 is provided with a pair of low-rigid portions 251, when the outer ring 141 of the first bearing 4 is press-fitted into the inner circumference of the pressing ring 250, as shown by a solid line in FIG.
  • the pressing ring 250 is deformed so that the shape becomes elliptical. This is because the low rigidity portion 251 has lower rigidity than other portions (for example, both ends 250b in the orthogonal direction) and is easily deformed.
  • both ends of the outer ring 141 of the first bearing 4 in the orthogonal direction (D2) are provided at both ends in the swing direction (D1) of the outer ring 141 of the first bearing 4.
  • a pressing force greater than the pressing force applied to both ends acts.
  • the pressing ring 250 acts on the first bearing 4 so that the pressing force in the orthogonal direction (D2) against the first bearing 4 is larger than the pressing force in the swing direction (D1) on the first bearing 4.
  • the outer ring 141 is pressed. Therefore, as the inner circumference of the pressing ring 250 is deformed into an elliptical shape, the outer ring 141 of the first bearing 4 is also deformed into an elliptical shape.
  • the pressing ring 250 before deformation is indicated by a two-dot chain line.
  • the distance between both ends 250a in the swinging direction (D1) of the pressing ring 250 after the deformation is larger than before the deformation. That is, the press ring 250 extends in the swing direction (D1) when the outer ring 141 is press-fitted.
  • the distance between both ends 250b of the pressing ring 250 in the orthogonal direction (D2) after the deformation is smaller than before. That is, the press ring 250 is compressed in the orthogonal direction (D2) by press-fitting the outer ring 141.
  • the axial width W1 of the pressing ring 250 is smaller than the axial width W2 of the outer ring 141 (W1 ⁇ W2).
  • the position of the pressing ring 250 is defined by being clamped between a step formed between the small diameter portion 230a and the large diameter portion 230b and the lock nut 5.
  • One end of the first bearing 4 protrudes from the pressing ring 250 in the axial direction (D3), and the protruding portion 4a of the first bearing 4 is fitted into the small-diameter portion 230a of the accommodation hole 230.
  • the fit between the projecting portion 4a of the first bearing 4 and the small-diameter portion 230a of the housing hole 230 is "clearance fit".
  • the inner circumference of the pressing ring 250 is not in contact with the protrusion 4a. That is, the protruding portion 4 a is a portion that does not receive the pressing force directly from the pressing ring 250. Thereby, the deformation of the protruding portion 4a due to the pressing force of the pressing ring 250 is suppressed, so that the protruding portion 4a can be fitted into the small-diameter portion 230a of the accommodation hole 230 by “clear fit”.
  • the outer ring 141 of the first bearing 4 can be compressed in the orthogonal direction (D2). Therefore, similarly to the first embodiment, the distance L1 between the inner raceway groove 142a and the outer raceway groove 141a in the orthogonal direction (D2) is equal to the distance L1 between the inner raceway groove 142a and the outer raceway groove 141a in the swing direction (D1).
  • the first bearing 4 can be deformed so as to be smaller than the distance L2 between the two (see FIGS. 6 to 8). Therefore, according to the second embodiment, the same operation and effect as those of the first embodiment can be obtained.
  • the compression amount of the first bearing 4 in the orthogonal direction (D2) can be set by the rigidity of the low rigidity portion 251.
  • the internal clearance 144 of the first bearing 4 in the orthogonal direction (D2) can be appropriately set.
  • ⁇ Modification 2> In the first embodiment, the example in which the bolt 150 functions as a pressing portion that presses the outer ring 141 has been described, but the present invention is not limited to this.
  • a pair of upper and lower through holes facing the housing hole 130 may be formed, and the outer ring 141 may be sandwiched from above and below by a clamp having a pair of pressing portions inserted into the through hole.
  • the outer ring 141 is deformed into an elliptical shape by applying a pressing force to each of the upper and lower portions of the outer peripheral surface of the outer ring 141 by a clamp or the like.
  • a pressing portion may be formed in the receiving hole 330 that receives the first bearing 4.
  • the housing hole 330 is formed between a pair of fitting surfaces 350 on both ends of the outer ring 141 of the first bearing 4 in the orthogonal direction (D2) by press-fitting, and the outer ring 141 of the first bearing 4.
  • a concave portion 353 that is disposed to face both ends in the first direction and that is depressed radially outward from the fitting surface 350.
  • the pair of fitting surfaces 350 are arc-shaped surfaces, and the inner diameter thereof is slightly smaller than the outer diameter of the outer ring 141 of the first bearing 4. Therefore, when the outer ring 141 of the first bearing 4 is press-fitted into the accommodation hole 330, the outer periphery of the outer ring 141 is pressed by the pair of fitting surfaces 350. That is, in the present modification, the pair of fitting surfaces 350 function as a pressing portion that presses the outer periphery of the outer ring 141 of the first bearing 4.
  • the depth of the recess 353 is set to a sufficient depth so as not to prevent the outer ring 141 of the first bearing 4 from being deformed into an elliptical shape. In this modification, the bottom surface of the recess 353 does not contact the outer ring 141. That is, no pressing force acts on the outer periphery of the outer ring 141 facing the recess 353.
  • the pair of fitting surfaces 350 is such that the pressing force in the orthogonal direction (D2) against the first bearing 4 is the pressing force in the swing direction (D1) against the first bearing 4 (in this modification, the first direction).
  • the outer ring 141 of the first bearing 4 is pressed so that the pressing force of (D1) is larger than 0 (zero).
  • the internal gap 144 of the first bearing 4 is secured in the orthogonal direction (D2) while the internal gap 144 of the first bearing 4 is secured in the swing direction (D1). It can be smaller than the internal gap 144 in the swing direction (D1).
  • This allows the inner ring 142 to move in the axial direction together with the worm shaft 2 when an axial force acts on the worm shaft 2 while allowing the worm shaft 2 to swing.
  • it is possible to reduce the collision noise caused by the ball 143 colliding with the outer ring 141 or the inner ring 142, and reduce the noise of the speed reducer.
  • the fitting surface 350 since the fitting surface 350 has a simple configuration in which the concave portion 353 is provided, it is possible to reduce the manufacturing cost of the speed reducer.
  • the outer periphery of the outer ring 141 and the outer raceway groove 141a may be deformed into an elliptical shape by forming the accommodation hole 130 into an elliptical shape and press-fitting the circular outer ring 141 into the accommodation hole 130. Further, by forming the accommodation hole 130 in a circular shape and pressing the elliptical outer ring 141 into the accommodation hole 130, the outer periphery of the outer ring 141 is deformed into a circular shape, and the outer raceway groove 141a of the outer ring 141 is formed into an elliptical shape. It may be deformed.
  • the contact portion of the housing hole 130 with the outer ring 141 functions as a pressing portion that deforms the outer ring 141.
  • pressing members such as the bolt 150 and the pressing ring 250 can be omitted. That is, when the pressing portion is formed in the receiving hole 330, the pressing portion formed in the receiving hole 330 presses the outer ring 141 of the first bearing 4 in the second direction (D2). The number of parts can be reduced as compared with the case of providing.
  • the present invention is not limited to this.
  • the outer race 141 having the elliptical outer raceway groove 141a may be fixed to the housing hole 130 in advance.
  • the outer raceway groove 141a can be made elliptical by removing the pressing force.
  • the elliptical outer raceway groove 141a is formed in the first bearing 4 in advance, so that the bolt 150 can be omitted.
  • the outer shape can be any shape.
  • the outer shape of the outer ring 141 can be circular.
  • the outer raceway groove 141a may be formed as a continuous curved surface. At least, the distance L1 between the inner raceway groove 142a and the outer raceway groove 141a in the orthogonal direction (D2) is smaller than the distance L2 between the inner raceway groove 142a and the outer raceway groove 141a in the swing direction (D1). I just need to be.
  • the first bearing 4 may be at least a ball bearing, and may be a self-aligning ball bearing or an angular ball bearing.
  • ⁇ Modification 8> In the above embodiment, an example was described in which the worm gear having the worm 2a as the drive gear and the worm wheel 1 as the driven gear was used as the speed reducer 100, but the present invention is not limited to this.
  • a hypoid gear having a hypoid pinion as a driving gear and a hypoid wheel as a driven gear may be used as a reduction gear. Further, a bevel gear may be used as a speed reducer.
  • the reduction gears 100 and 200 each include a drive gear shaft (worm shaft 2) connected to a drive source (electric motor 7) and a driven gear (worm wheel 1) that meshes with the drive gear shaft (worm shaft 2).
  • a first bearing 4 rotatably supporting a base end side of a drive gear shaft (worm shaft 2) and a second bearing 11 rotatably supporting a distal end side of the drive gear shaft (worm shaft 2).
  • a biasing member for biasing the drive gear shaft (worm shaft 2) toward the driven gear (worm wheel 1) via the second bearing 11;
  • An inner race 142 having an inner race groove 142a, an outer race 141 having an outer race groove 141a, and a plurality of rolling elements (balls 143) arranged between the inner race groove 142a and the outer race groove 141a.
  • Drive gear shaft W The inner raceway groove 142a and the outer raceway in a second direction (D2) orthogonal to the first direction (D1) in which the shaft 2) swings and the axial direction (D3) of the drive gear shaft (worm shaft 2).
  • the distance L1 between the raceway groove 141a and the distance L2 between the inner raceway groove 142a and the outer raceway groove 141a in the first direction (D1) is smaller.
  • the internal clearance 144 of the first bearing 4 is secured in the second direction (D2) while the internal clearance 144 of the first bearing 4 is secured in the first direction (D1).
  • the inner ring 142 is formed together with the drive gear shaft (worm shaft 2). Movement in the axial direction can be suppressed.
  • the reduction gears 100 and 200 further include a pressing portion (a bottom portion 131, a bolt 150, a pressing ring 250, and a fitting surface 350) that presses the outer ring 141 of the first bearing 4 in the second direction (D2).
  • the outer race 141 is held in a state where it is pressed by the pressing portions (the bottom 131, the bolt 150, the pressing ring 250, the fitting surface 350), so that the inner raceway groove 142a and the outer raceway groove in the second direction (D2).
  • the distance L1 between the outer raceway 141a and the inner raceway groove 142a is smaller than the distance L2 between the inner raceway groove 142a and the outer raceway groove 141a in the first direction (D1).
  • the inner space 144 of the first bearing 4 in the second direction (D2) can be easily reduced by deforming the outer ring 141 by the pressing portion (the bottom 131, the bolt 150, the pressing ring 250, the fitting surface 350). can do.
  • the reduction gears 100 and 200 each include a drive gear shaft (worm shaft 2) connected to a drive source (electric motor 7) and a driven gear (worm wheel 1) that meshes with the drive gear shaft (worm shaft 2).
  • a first bearing 4 rotatably supporting a base end side of a drive gear shaft (worm shaft 2) and a second bearing 11 rotatably supporting a distal end side of the drive gear shaft (worm shaft 2).
  • an urging member coil spring 12 for urging the drive gear shaft (worm shaft 2) toward the driven gear (worm wheel 1) via the second bearing 11, and presses the outer periphery of the first bearing 4.
  • the first bearing 4 includes an inner race 142 having an inner raceway groove 142a and an outer racer 141 having an outer raceway groove 141a, and a pressing portion (bottom 131, bolt 150, pressing ring 250, fitting surface 350).
  • Inner track groove 142 And a plurality of rolling elements (balls 143) disposed between the outer raceway groove 141a and the outer raceway groove 141a.
  • the pressing portion (the bottom portion 131, the bolt 150, the pressing ring 250, and the fitting surface 350) includes a driving gear shaft ( The direction in which the worm shaft 2) swings is defined as a first direction (D1), and the direction orthogonal to each of the first direction (D1) and the axial direction (D3) of the drive gear shaft (worm shaft 2) is defined as a second direction (D1). D2), the outer ring 141 of the first bearing 4 such that the pressing force on the first bearing 4 in the second direction (D2) is greater than the pressing force on the first bearing 4 in the first direction (D1). Press.
  • the internal clearance 144 of the first bearing 4 is secured in the second direction (D2) while the internal clearance 144 of the first bearing 4 is secured in the first direction (D1).
  • the inner ring 142 is formed together with the drive gear shaft (worm shaft 2). Movement in the axial direction can be suppressed.
  • the pressing portion is a bolt 150 that is movable in the second direction (D2), and the first bearing 4 is configured such that the first bearing 4 moves the inner raceway groove 142a in the second direction (D2) in accordance with the screwing amount of the bolt 150.
  • the distance L1 between the outer raceway groove 141a and the outer raceway groove 141a is configured to be adjustable.
  • the internal clearance 144 of the first bearing 4 in the second direction (D2) can be easily adjusted by the screwing amount of the bolt 150.
  • the pressing portion is an annular member (pressing ring 250) into which the outer ring 141 of the first bearing 4 is press-fitted, and is provided at both ends 250 a in the first direction (D 1) in the second direction (D 2).
  • a low-rigidity portion 251 having lower rigidity than both ends 250b is provided.
  • the outer ring 141 of the first bearing 4 can be compressed in the second direction (D2) by press-fitting the first bearing 4 into the annular pressing portion (the pressing ring 250). It can be set by the rigidity of the low rigidity portion 251.
  • the low-rigidity portion 251 is a thin portion that is thinner than the thickness of both ends 250b in the second direction (D2).
  • the reduction gears 100 and 200 further include a case (gear case 3, 203) for accommodating the drive gear shaft (worm shaft 2), and the case (gear case 3, 203) has an accommodation hole 130, for accommodating the first bearing 4. 330 is formed, and the pressing portion (the bottom portion 131, the fitting surface 350) is formed in the receiving holes 130 and 330.
  • the outer ring 141 of the first bearing 4 is pressed in the second direction (D2) by the pressing portions (the bottom portion 131, the fitting surface 350) formed in the receiving holes 130 and 330.
  • the number of parts can be reduced as compared with the case where a pressing portion is provided separately from 203).
  • the housing hole 330 has a pair of fitting surfaces 350 into which both ends of the outer ring 141 of the first bearing 4 in the second direction (D2) are press-fitted, and the outer ring 141 of the first bearing 4. And a recess 353 which is disposed opposite to both ends in the first direction (D1) and is depressed radially outward from the fitting surface 350.
  • the pair of fitting surfaces 350 presses the outer ring 141. Department.
  • the power steering device 10 includes the speed reducer 100 and an electric motor 7 as a drive source.
  • a driven gear (worm wheel 1) applies a torque of the electric motor 7 to a rack shaft 8 that steers the wheels 6.
  • the reduction gear 100 is provided on the output shaft 22 for transmission, and reduces the rotation of the drive gear shaft (worm shaft 2) and transmits the rotation to the driven gear (worm wheel 1).

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  • Engineering & Computer Science (AREA)
  • General Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
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  • Power Steering Mechanism (AREA)

Abstract

This reducer (100) is provided with: a first bearing (4) that supports a base end side of a driving gear shaft; a second bearing that supports the front end side of the driving gear shaft; and a biasing member that biases the driving gear shaft toward a driven gear. The first bearing (4) has an inner ring (142) having an inner race groove (142a) and an outer ring (141) having an outer race groove (141a), wherein the distance (L1) between the inner race groove (142a) and the outer race groove (141a) in a second direction (D2) perpendicular to each of a first direction (D1), in which the driving gear shaft swings, and the axial direction (D3) of the driving gear shaft is smaller than the distance (L2) between the inner race groove (142a) and the outer race groove (141a) in the first direction (D1).

Description

減速機及びパワーステアリング装置Reduction gear and power steering device
　本発明は、減速機及びパワーステアリング装置に関する。 The present invention relates to a speed reducer and a power steering device.
　ウォーム減速機を備えたパワーステアリング装置が知られている（ＪＰ２０１６－３７６０Ａ参照）。ウォーム減速機は、電動モータ等の駆動源により回転駆動されるウォーム軸と、ウォーム軸と噛み合うウォームホイールと、を備える。ウォーム軸は、両端部が軸受によって回転可能に支持される。 パ ワ ー A power steering device equipped with a worm speed reducer is known (see JP2016-3760A). The worm speed reducer includes a worm shaft that is rotationally driven by a drive source such as an electric motor, and a worm wheel that meshes with the worm shaft. Both ends of the worm shaft are rotatably supported by bearings.
　このようなウォーム減速機では、ウォーム軸の基端部が電動モータの回転軸に対して揺動可能に連結され、ウォーム軸の先端部が付勢部材によってウォームホイール側に付勢されている。なお、ウォーム軸の基端部を支持する軸受には、内輪が外輪に対して揺動できるように、内部隙間が設けられている。このように、軸受に内部隙間が設けられているので、ウォーム軸に軸方向の力が作用したときに、ウォーム軸とともに内輪が軸方向にわずかに移動することにより、転動体（玉）が外輪または内輪と衝突して騒音（衝突音）が発生するおそれがある。 In such a worm speed reducer, the base end of the worm shaft is swingably connected to the rotating shaft of the electric motor, and the distal end of the worm shaft is urged toward the worm wheel by the urging member. The bearing supporting the base end of the worm shaft is provided with an internal clearance so that the inner ring can swing with respect to the outer ring. As described above, since the bearing is provided with the internal clearance, when an axial force acts on the worm shaft, the inner ring moves slightly in the axial direction together with the worm shaft, so that the rolling element (ball) is moved to the outer ring. Alternatively, there is a possibility that noise (collision sound) is generated by colliding with the inner ring.
　本発明は、減速機の騒音を低減することを目的とする。 The present invention aims to reduce the noise of the speed reducer.
　本発明のある態様によれば、駆動源に連結された駆動歯車軸と、前記駆動歯車軸に噛み合う従動歯車とを備えた減速機であって、前記駆動歯車軸の基端側を回転自在に支持する第１軸受と、前記駆動歯車軸の先端側を回転自在に支持する第２軸受と、前記第２軸受を介して、前記駆動歯車軸を前記従動歯車へ向けて付勢する付勢部材と、を備え、前記第１軸受は、内側軌道溝を有する内輪と、外側軌道溝を有する外輪と、前記内側軌道溝と前記外側軌道溝との間に配置される複数の転動体と、を有し、前記駆動歯車軸が揺動する方向である第１方向及び前記駆動歯車軸の軸方向のそれぞれに直交する第２方向における前記内側軌道溝と前記外側軌道溝との間の距離が、前記第１方向における前記内側軌道溝と前記外側軌道溝との間の距離よりも小さい。 According to an aspect of the present invention, there is provided a speed reducer including a drive gear shaft connected to a drive source, and a driven gear meshing with the drive gear shaft, wherein a base end side of the drive gear shaft is rotatable. A first bearing for supporting, a second bearing for rotatably supporting the distal end side of the drive gear shaft, and an urging member for urging the drive gear shaft toward the driven gear via the second bearing. Wherein the first bearing comprises: an inner ring having an inner raceway groove; an outer ring having an outer raceway groove; and a plurality of rolling elements disposed between the inner raceway groove and the outer raceway groove. A distance between the inner raceway groove and the outer raceway groove in a first direction, which is a direction in which the drive gear shaft swings, and in a second direction orthogonal to each of the axial directions of the drive gear shaft, The distance between the inner raceway groove and the outer raceway groove in the first direction; It is also small.
　本発明の別の態様によれば、駆動源に連結された駆動歯車軸と、前記駆動歯車軸に噛み合う従動歯車とを備えた減速機であって、前記駆動歯車軸の基端側を回転自在に支持する第１軸受と、前記駆動歯車軸の先端側を回転自在に支持する第２軸受と、前記第２軸受を介して、前記駆動歯車軸を前記従動歯車へ向けて付勢する付勢部材と、前記第１軸受の外周を押圧する押圧部と、を備え、前記第１軸受は、内側軌道溝を有する内輪と、外側軌道溝を有する外輪と、前記内側軌道溝と前記外側軌道溝との間に配置される複数の転動体と、を有し、前記押圧部は、前記駆動歯車軸が揺動する方向を第１方向とし、前記第１方向及び前記駆動歯車軸の軸方向のそれぞれに直交する方向を第２方向としたとき、前記第１軸受に対する前記第２方向の押圧力が、前記第１軸受に対する前記第１方向の押圧力よりも大きくなるように、前記第１軸受の前記外輪を押圧する。 According to another aspect of the present invention, there is provided a speed reducer including a drive gear shaft connected to a drive source, and a driven gear meshing with the drive gear shaft, wherein a base end side of the drive gear shaft is rotatable. , A second bearing rotatably supporting the distal end side of the drive gear shaft, and a bias for biasing the drive gear shaft toward the driven gear via the second bearing. A member, and a pressing portion for pressing an outer periphery of the first bearing, wherein the first bearing has an inner race having an inner race groove, an outer race having an outer race groove, the inner race groove, and the outer race groove. And a plurality of rolling elements disposed between the first and second pressing members, wherein the pressing portion sets a direction in which the drive gear shaft swings as a first direction, and includes a first direction and an axial direction of the drive gear shaft. When a direction orthogonal to each is defined as a second direction, the second direction with respect to the first bearing Pressure, the to be larger than the pressing force of the first direction relative to the first bearing, to press the outer ring of the first bearing.
　本発明のさらに別の態様によれば、前記減速機と、前記駆動源としての電動モータと、を備えたパワーステアリング装置であって、前記従動歯車は、車輪を転舵するラック軸に前記電動モータの回転力を伝達する出力軸に設けられ、前記減速機は、前記駆動歯車軸の回転を減速して、前記従動歯車に伝達する。 According to still another aspect of the present invention, there is provided a power steering device including the speed reducer and an electric motor serving as the drive source, wherein the driven gear is provided on a rack shaft that steers a wheel. The speed reducer is provided on an output shaft that transmits a rotational force of a motor, and reduces the rotation of the drive gear shaft and transmits the rotation to the driven gear.
図１は、本発明の第１実施形態に係る減速機を備えたパワーステアリング装置の構成図である。FIG. 1 is a configuration diagram of a power steering device including a speed reducer according to a first embodiment of the present invention. 図２は、本発明の第１実施形態に係る減速機を備えたパワーステアリング装置の断面図である。FIG. 2 is a cross-sectional view of a power steering device including the speed reducer according to the first embodiment of the present invention. 図３Ａは、軸受の断面模式図であり、内輪が外輪に対して傾いていない状態を示す。FIG. 3A is a schematic cross-sectional view of the bearing, showing a state where the inner ring is not inclined with respect to the outer ring. 図３Ｂは、軸受の断面模式図であり、内輪が外輪に対して傾いている状態を示す。FIG. 3B is a schematic cross-sectional view of the bearing, showing a state where the inner ring is inclined with respect to the outer ring. 図４は、ギヤケースを一部破断した減速機の斜視図である。FIG. 4 is a perspective view of the speed reducer with a gear case partially cut away. 図５は、図４のＶ－Ｖ線に沿う減速機の断面模式図である。FIG. 5 is a schematic sectional view of the speed reducer taken along line VV in FIG. 図６は、図７及び図８のＶＩ－ＶＩ線に沿う第１軸受の内輪と外輪の断面模式図である。FIG. 6 is a schematic cross-sectional view of the inner ring and the outer ring of the first bearing along the line VI-VI in FIGS. 7 and 8. 図７は、図６のＶＩＩ－ＶＩＩ線に沿う第１軸受の断面模式図である。FIG. 7 is a schematic sectional view of the first bearing taken along line VII-VII in FIG. 図８は、図６のＶＩＩＩ－ＶＩＩＩ線に沿う第１軸受の断面模式図である。FIG. 8 is a schematic sectional view of the first bearing taken along line VIII-VIII in FIG. 図９は、本発明の第２実施形態に係る減速機の断面模式図である。FIG. 9 is a schematic sectional view of a speed reducer according to a second embodiment of the present invention. 図１０は、本発明の第２実施形態に係る減速機に用いられる押圧リングを示す図である。FIG. 10 is a diagram illustrating a pressing ring used in a speed reducer according to a second embodiment of the present invention. 図１１は、軸受が圧入されることにより変形した押圧リングを示す図である。FIG. 11 is a diagram illustrating a pressing ring deformed by press-fitting a bearing. 図１２は、変形例に係る減速機の収容孔に設けられる押圧部について示す断面模式図である。FIG. 12 is a schematic cross-sectional view illustrating a pressing portion provided in a housing hole of a speed reducer according to a modification.
　＜第１実施形態＞
　図面を参照して、本発明の第１実施形態に係る減速機を備えたパワーステアリング装置について説明する。パワーステアリング装置は、車両に搭載されドライバーが操舵ハンドルに加える操舵力を補助する装置である。 <First embodiment>
A power steering device including a speed reducer according to a first embodiment of the present invention will be described with reference to the drawings. A power steering device is a device that is mounted on a vehicle and assists a steering force applied by a driver to a steering wheel.
　図１及び図２に示すように、パワーステアリング装置１０は、減速機１００と、駆動源としての電動モータ７と、を備える。減速機１００は、電動モータ７の出力シャフト７ａに連結され電動モータ７の駆動に伴って回転する駆動歯車軸としてのウォーム軸２と、ウォーム軸２に形成された駆動歯車としてのウォーム２ａに噛み合う従動歯車としてのウォームホイール１と、ウォーム軸２及びウォームホイール１を収容するケースであるギヤケース３と、ウォーム軸２を支持する軸支持構造１０１と、を備える。ウォーム軸２と電動モータ７の出力シャフト７ａとは、軸ずれを許容する軸連結器１９によって連結される。 パ ワ ー As shown in FIGS. 1 and 2, the power steering device 10 includes a speed reducer 100 and an electric motor 7 as a drive source. The speed reducer 100 is connected to an output shaft 7 a of the electric motor 7 and meshes with a worm shaft 2 as a drive gear shaft that rotates with the driving of the electric motor 7, and a worm 2 a as a drive gear formed on the worm shaft 2. The worm wheel 1 includes a worm wheel 1 as a driven gear, a gear case 3 that is a case that houses the worm shaft 2 and the worm wheel 1, and a shaft support structure 101 that supports the worm shaft 2. The worm shaft 2 and the output shaft 7a of the electric motor 7 are connected by a shaft connecting device 19 that allows a shaft deviation.
　操舵ハンドル１６にはステアリングシャフト２０が連結され、ステアリングシャフト２０は操舵ハンドル１６の回転に伴って回転する。ステアリングシャフト２０は、操舵ハンドル１６に連係する入力軸２１と、ラック軸８に連係する出力軸２２と、入力軸２１と出力軸２２を連結するトーションバー２３と、を備える。ウォームホイール１は出力軸２２に設けられる。 ス テ ア リ ン グ A steering shaft 20 is connected to the steering wheel 16, and the steering shaft 20 rotates with the rotation of the steering wheel 16. The steering shaft 20 includes an input shaft 21 linked to the steering wheel 16, an output shaft 22 linked to the rack shaft 8, and a torsion bar 23 connecting the input shaft 21 and the output shaft 22. The worm wheel 1 is provided on the output shaft 22.
　パワーステアリング装置１０は、運転者によるステアリング操作に伴う入力軸２１と出力軸２２との相対回転によってトーションバー２３に作用する操舵トルクを検出するトルクセンサ２４と、トルクセンサ２４にて検出された操舵トルクに基づいて電動モータ７の駆動を制御するコントローラ２５と、をさらに備える。電動モータ７から出力されたトルクは、ウォーム軸２からウォームホイール１に伝達されて出力軸２２にアシストトルクとして付与される。このように、パワーステアリング装置１０は、トルクセンサ２４の検出結果に基づいて電動モータ７の駆動をコントローラ２５にて制御して運転者のステアリング操作を補助する。 The power steering device 10 includes a torque sensor 24 that detects a steering torque acting on a torsion bar 23 by a relative rotation between an input shaft 21 and an output shaft 22 caused by a driver's steering operation, and a steering detected by the torque sensor 24. A controller that controls the driving of the electric motor based on the torque. The torque output from the electric motor 7 is transmitted from the worm shaft 2 to the worm wheel 1 and applied to the output shaft 22 as assist torque. As described above, the power steering device 10 assists the driver in steering by controlling the driving of the electric motor 7 by the controller 25 based on the detection result of the torque sensor 24.
　減速機１００は、電動モータ７の駆動に伴ってウォーム軸２が回転すると、ウォーム軸２の回転を減速してウォームホイール１に伝達する。これにより、ウォームホイール１が設けられる出力軸２２が、車輪６を転舵するラック軸８に電動モータ７の回転力を伝達する。 When the worm shaft 2 rotates with the driving of the electric motor 7, the speed reducer 100 reduces the rotation of the worm shaft 2 and transmits the rotation to the worm wheel 1. Thus, the output shaft 22 provided with the worm wheel 1 transmits the torque of the electric motor 7 to the rack shaft 8 that steers the wheels 6.
　図２に示すように、ウォーム軸２は金属製のギヤケース３に収容され、電動モータ７はギヤケース３に取り付けられる。ウォーム２ａには、ウォームホイール１の歯部１ａと噛み合う歯部２ｅが形成される。ギヤケース３には歯部２ｅに対応する位置に開口部３ｃが形成され、その開口部３ｃを通じてウォーム２ａの歯部２ｅとウォームホイール１の歯部１ａとが噛み合う。 ウ ォ ー As shown in FIG. 2, the worm shaft 2 is housed in a metal gear case 3, and the electric motor 7 is attached to the gear case 3. The worm 2a is formed with teeth 2e that mesh with the teeth 1a of the worm wheel 1. An opening 3c is formed in the gear case 3 at a position corresponding to the tooth 2e, and the tooth 2e of the worm 2a and the tooth 1a of the worm wheel 1 mesh with each other through the opening 3c.
　減速機１００の軸支持構造１０１は、ウォーム軸２の基端側（電動モータ７側）を回転自在に支持する第１軸受４と、ウォーム軸２の先端側（電動モータ７側とは反対側）を回転自在に支持する第２軸受１１と、第２軸受１１を介して、ウォーム軸２をウォームホイール１へ向けて付勢する付勢部材としてのコイルスプリング１２と、を備える。ウォーム軸２は、ギヤケース３内において、一対の軸受（第１軸受４及び第２軸受１１）によって回転自在に支持される。ウォーム軸２の軸方向（中心軸方向）は、単に軸方向（Ｄ３）とも記す。 The shaft support structure 101 of the speed reducer 100 includes a first bearing 4 that rotatably supports the base end side (the electric motor 7 side) of the worm shaft 2 and a distal end side (the side opposite to the electric motor 7 side) of the worm shaft 2. ), And a coil spring 12 as an urging member for urging the worm shaft 2 toward the worm wheel 1 via the second bearing 11. The worm shaft 2 is rotatably supported in the gear case 3 by a pair of bearings (a first bearing 4 and a second bearing 11). The axial direction (center axis direction) of the worm shaft 2 is also simply referred to as the axial direction (D3).
　第１軸受４は、環状の外輪１４１と内輪１４２の間に転動体としてのボール（玉）１４３が介在される深溝玉軸受である。第１軸受４は、ギヤケース３に設けられる収容孔１３０内に収容される。第１軸受４の外輪１４１は、ギヤケース３に形成された段部３ａとギヤケース３内に締結されたロックナット５との間で軸方向（Ｄ３）に挟持される。第１軸受４の内輪１４２は、ウォーム軸２に圧入されることにより固定される。内輪１４２は、ウォーム軸２の段部２ｂとウォーム軸２の端部に圧入される軸連結器１９のウォーム側ジョイント９との間で軸方向（Ｄ３）に挟持される。 The first bearing 4 is a deep groove ball bearing in which a ball (ball) 143 as a rolling element is interposed between the annular outer ring 141 and the inner ring 142. The first bearing 4 is housed in a housing hole 130 provided in the gear case 3. The outer ring 141 of the first bearing 4 is held in the axial direction (D3) between the stepped portion 3a formed in the gear case 3 and the lock nut 5 fastened in the gear case 3. The inner ring 142 of the first bearing 4 is fixed by being pressed into the worm shaft 2. The inner ring 142 is sandwiched in the axial direction (D3) between the step portion 2b of the worm shaft 2 and the worm-side joint 9 of the shaft coupler 19 that is press-fitted into the end of the worm shaft 2.
　第１軸受４は、ウォームホイール１に向かうウォーム軸２の揺動を許容するための内部隙間１４４（図７参照）を有する。ウォーム軸２が第１軸受４を中心に揺動する方向である第１方向は、揺動方向（Ｄ１）と記す。第１軸受４の詳細については、後述する。 The first bearing 4 has an internal clearance 144 (see FIG. 7) for allowing the worm shaft 2 to swing toward the worm wheel 1. A first direction in which the worm shaft 2 swings about the first bearing 4 is referred to as a swing direction (D1). Details of the first bearing 4 will be described later.
　第２軸受１１は、環状の外輪と内輪の間に転動体としてのボール（玉）が介在される深溝玉軸受である。第２軸受１１は、ギヤケース３の底部に収装される。第２軸受１１の内輪にはウォーム軸２の先端部付近に形成された段部２ｃが係止される。 The second bearing 11 is a deep groove ball bearing in which a ball (ball) as a rolling element is interposed between an annular outer ring and an inner ring. The second bearing 11 is housed at the bottom of the gear case 3. A step 2c formed near the tip of the worm shaft 2 is locked to the inner ring of the second bearing 11.
　ギヤケース３の外周面には、端面１７ａが平面状のフランジ部１７が突出して形成される。フランジ部１７には、第２軸受１１の外周面に臨んで開口する貫通孔１３が形成される。フランジ部１７の端面１７ａに開口する貫通孔１３の開口部はプラグ１４によって閉塞される。 端 An end surface 17 a is formed on the outer peripheral surface of the gear case 3 so as to protrude from a flat flange portion 17. A through hole 13 is formed in the flange portion 17 and opens toward the outer peripheral surface of the second bearing 11. The opening of the through hole 13 that opens to the end face 17 a of the flange 17 is closed by the plug 14.
　コイルスプリング１２は、貫通孔１３において、プラグ１４の先端面と第２軸受１１の外周面との間で圧縮された状態で収装される。コイルスプリング１２は、ウォーム２ａの歯部２ｅとウォームホイール１の歯部１ａとの隙間が小さくなる方向に、つまりウォーム２ａがウォームホイール１に噛み合う方向に、第２軸受１１を付勢する。 The coil spring 12 is housed in a state where the coil spring 12 is compressed between the distal end surface of the plug 14 and the outer peripheral surface of the second bearing 11 in the through hole 13. The coil spring 12 urges the second bearing 11 in a direction in which a gap between the teeth 2e of the worm 2a and the teeth 1a of the worm wheel 1 is reduced, that is, in a direction in which the worm 2a meshes with the worm wheel 1.
　ギヤケース３における第２軸受１１の外周面を囲う内周面３ｂは、第２軸受１１がコイルスプリング１２の付勢力によってウォームホイール１に向けて移動できるように、互いに平行な一対の平面部を有する長穴形状に形成される。なお、内周面３ｂは、第２軸受１１が内周面３ｂの内側で移動できる限り、どのような形状であってもよい。例えば、内周面３ｂは、その内径が第２軸受１１の外径よりも大きい丸穴形状であってもよく、互いに平行な一対の平面部が形成されている必要はない。 The inner peripheral surface 3b surrounding the outer peripheral surface of the second bearing 11 in the gear case 3 has a pair of parallel flat portions so that the second bearing 11 can move toward the worm wheel 1 by the urging force of the coil spring 12. It is formed in a long hole shape. The inner peripheral surface 3b may have any shape as long as the second bearing 11 can move inside the inner peripheral surface 3b. For example, the inner peripheral surface 3b may have a round hole shape whose inner diameter is larger than the outer diameter of the second bearing 11, and there is no need to form a pair of parallel flat portions.
　ギヤケース３内へのウォーム軸２の組み付けが完了した初期時点では、第２軸受１１は、コイルスプリング１２の付勢力によってウォームホイール１側に付勢され、ウォーム２ａとウォームホイール１との間のバックラッシ（隙間）がない状態となる。この状態では、ウォーム軸２は、コイルスプリング１２の付勢力によって第１軸受４を支点として傾く。 At an initial point in time when the worm shaft 2 has been assembled into the gear case 3, the second bearing 11 is urged toward the worm wheel 1 by the urging force of the coil spring 12, and the backlash between the worm 2a and the worm wheel 1 is increased. There is no (gap). In this state, the worm shaft 2 is tilted about the first bearing 4 as a fulcrum by the urging force of the coil spring 12.
　パワーステアリング装置１０の駆動に伴ってウォーム２ａとウォームホイール１の歯部１ａ，２ｅの摩耗が進むと、コイルスプリング１２の付勢力によって第２軸受１１がギヤケース３の長穴内を移動し、ウォーム軸２とウォームホイール１との歯部１ａ，２ｅのバックラッシが低減する。したがって、バックラッシが安定して低減されるためには、ウォーム軸２がウォームホイール１に向かってスムーズに揺動することが必要となる。 When the worm 2a and the teeth 1a, 2e of the worm wheel 1 wear as the power steering device 10 is driven, the second bearing 11 moves in the elongated hole of the gear case 3 by the urging force of the coil spring 12, and the worm shaft Backlash between the tooth portions 1a and 2e between the worm wheel 2 and the worm wheel 1 is reduced. Therefore, in order to stably reduce the backlash, the worm shaft 2 needs to swing smoothly toward the worm wheel 1.
　図３Ａ及び図３Ｂに示すように、第１軸受４には、ウォーム軸２に固定される内輪１４２が、ギヤケース３に固定される外輪１４１に対して揺動できるように、内部隙間１４４が設けられる。なお、図３Ａ及び図３Ｂにおいて、第１軸受４の内輪１４２の内径は、図２に示すものに比べて小さく記載され、内部隙間１４４は、誇張して大きく記載されている。 As shown in FIGS. 3A and 3B, the first bearing 4 is provided with an internal gap 144 so that the inner ring 142 fixed to the worm shaft 2 can swing with respect to the outer ring 141 fixed to the gear case 3. Can be 3A and 3B, the inner diameter of the inner ring 142 of the first bearing 4 is described smaller than that shown in FIG. 2, and the internal gap 144 is exaggerated and described larger.
　仮に、第１軸受４の全周に亘って内部隙間１４４が設けられる場合、ウォーム軸２に軸方向（Ｄ３）の力が作用すると、ウォーム軸２とともに内輪１４２が軸方向（Ｄ３）にわずかに移動することがある。このため、例えば、切り返し操舵時に電動モータ７からウォーム軸２に軸方向（Ｄ３）の力が作用した場合に、ボール１４３が外輪１４１または内輪１４２と衝突して、騒音（衝突音）が発生するおそれがある。また、路面から車輪６、ラック軸８、出力軸２２等を介してウォームホイール１からウォーム軸２に軸方向（Ｄ３）の力が作用した場合に、同様に騒音（衝突音）が発生するおそれもある。 If the internal clearance 144 is provided over the entire circumference of the first bearing 4, when a force in the axial direction (D3) acts on the worm shaft 2, the inner ring 142 together with the worm shaft 2 slightly moves in the axial direction (D3). May move. Therefore, for example, when a force in the axial direction (D3) acts on the worm shaft 2 from the electric motor 7 at the time of reverse steering, the ball 143 collides with the outer ring 141 or the inner ring 142, and noise (collision sound) is generated. There is a risk. Also, when a force in the axial direction (D3) acts on the worm shaft 2 from the worm wheel 1 via the wheels 6, the rack shaft 8, the output shaft 22, and the like from the road surface, noise (collision noise) may similarly be generated. There is also.
　そこで、本実施形態では、ウォーム軸２のスムーズな揺動を許容するとともにボール１４３が外輪１４１または内輪１４２と衝突することに起因した衝突音の発生を防止するために、第１軸受４の内部隙間１４４の大きさが周方向の位置に応じて異なるようにした。本実施形態では、揺動方向（Ｄ１）では所定長さＸ（＞０）の内部隙間１４４を確保しつつ、揺動方向（Ｄ１）及びウォーム軸２の軸方向（Ｄ３）のそれぞれに直交する第２方向である直交方向（Ｄ２）では内部隙間１４４が０、あるいはほぼ０となるようにした。 Therefore, in the present embodiment, in order to allow the worm shaft 2 to swing smoothly and prevent the generation of a collision sound caused by the ball 143 colliding with the outer ring 141 or the inner ring 142, the inside of the first bearing 4 is set. The size of the gap 144 is made different depending on the position in the circumferential direction. In the present embodiment, in the swing direction (D1), an internal gap 144 having a predetermined length X (> 0) is secured, and each is orthogonal to the swing direction (D1) and the axial direction (D3) of the worm shaft 2. In the orthogonal direction (D2) which is the second direction, the internal gap 144 is set to 0 or almost 0.
　図４及び図５を参照して、直交方向（Ｄ２）における第１軸受４の支持構造について説明する。図４は、ギヤケース３を一部破断した減速機１００の斜視図である。図４において、ウォームホイール１の図示は省略している。図５は、図４のＶ－Ｖ線に沿う減速機１００の断面模式図である。 支持 With reference to FIGS. 4 and 5, the support structure of the first bearing 4 in the orthogonal direction (D2) will be described. FIG. 4 is a perspective view of the speed reducer 100 with the gear case 3 partially cut away. 4, illustration of the worm wheel 1 is omitted. FIG. 5 is a schematic cross-sectional view of the speed reducer 100 along the line VV in FIG.
　図４及び図５に示すように、減速機１００の軸支持構造１０１は、第１軸受４の外輪１４１の外周を直交方向（Ｄ２）に押圧する押圧部としてのボルト１５０をさらに備える。ギヤケース３には、ボルト１５０が挿通される挿通孔１３３が形成される。挿通孔１３３は、直交方向（Ｄ２）に貫通する貫通孔であり、その内周面にはボルト１５０の軸部の外周に形成されたおねじに螺合するめねじが形成される。このため、ギヤケース３の外側から工具等を用いてボルト１５０を回転させることにより、ボルト１５０を挿通孔１３３に沿って直交方向（Ｄ２）に移動させることができる。収容孔１３０において、挿通孔１３３に対向する底部１３１は、第１軸受４を支持する支持部とされる。つまり、ギヤケース３の収容孔１３０は軸支持構造１０１の一部を構成し、収容孔１３０の底部１３１は第１軸受４の外輪１４１の外周を直交方向（Ｄ２）に押圧する押圧部として機能する。第１軸受４の外輪１４１は、押圧部としてのボルト１５０と、収容孔１３０に形成される押圧部としての底部１３１との間で直交方向（Ｄ２）に挟持される。 As shown in FIGS. 4 and 5, the shaft support structure 101 of the speed reducer 100 further includes a bolt 150 as a pressing portion that presses the outer periphery of the outer ring 141 of the first bearing 4 in the orthogonal direction (D2). The gear case 3 has an insertion hole 133 through which the bolt 150 is inserted. The insertion hole 133 is a through hole that penetrates in the orthogonal direction (D2), and a female screw that is screwed to a male screw formed on the outer periphery of the shaft of the bolt 150 is formed on the inner peripheral surface. Therefore, by rotating the bolt 150 from outside the gear case 3 using a tool or the like, the bolt 150 can be moved in the orthogonal direction (D2) along the insertion hole 133. In the receiving hole 130, the bottom 131 that faces the insertion hole 133 is a support that supports the first bearing 4. That is, the housing hole 130 of the gear case 3 forms a part of the shaft support structure 101, and the bottom 131 of the housing hole 130 functions as a pressing portion that presses the outer circumference of the outer ring 141 of the first bearing 4 in the orthogonal direction (D2). . The outer ring 141 of the first bearing 4 is sandwiched in the orthogonal direction (D2) between the bolt 150 as a pressing portion and the bottom 131 as a pressing portion formed in the housing hole 130.
　図５において二点鎖線で示すように、第１軸受４の外輪１４１は、ギヤケース３に組み付けられる前の状態において、外周及び内周がそれぞれ円形状である。第１軸受４が収容孔１３０に収容され、ボルト１５０がねじ込まれることにより、第１軸受４の外輪１４１は、直交方向（Ｄ２）において圧縮されるとともに、揺動方向（Ｄ１）に膨張するように変形する。このため、図５において実線で示すように、第１軸受４の外輪１４１は、ギヤケース３に組み付けられ、ボルト１５０が所定量だけねじ込まれた後の状態において、外周及び内周がそれぞれ楕円形状になる。 As shown by a two-dot chain line in FIG. 5, the outer ring 141 of the first bearing 4 has a circular outer and inner circumference before being assembled to the gear case 3. When the first bearing 4 is accommodated in the accommodation hole 130 and the bolt 150 is screwed, the outer ring 141 of the first bearing 4 is compressed in the orthogonal direction (D2) and expands in the swing direction (D1). Deform to. For this reason, as shown by a solid line in FIG. 5, the outer ring 141 of the first bearing 4 is assembled to the gear case 3 and, after the bolt 150 is screwed by a predetermined amount, the outer circumference and the inner circumference each have an elliptical shape. Become.
　ボルト１５０は、その中心軸の延長線上にウォーム軸２の中心軸が位置するように配置される。このため、ボルト１５０は、外輪１４１の外周面をウォーム軸２の中心軸に向かって押圧する。 The bolt 150 is arranged such that the central axis of the worm shaft 2 is located on an extension of the central axis. For this reason, the bolt 150 presses the outer peripheral surface of the outer ring 141 toward the central axis of the worm shaft 2.
　ボルト１５０の軸部の先端面１５１は、ボルト１５０により外輪１４１が押圧されたときに、外輪１４１が楕円形状に変形することを阻害することがないように形成される。本実施形態では、ボルト１５０の軸部の先端面１５１は、平面状に形成される。また、収容孔１３０の内周面は、ボルト１５０により外輪１４１が押圧されたときに、外輪１４１が楕円形状に変形することを阻害することがないように形成される。例えば、収容孔１３０の底部１３１の内周面の曲率半径は、楕円形状に変形した外輪１４１において底部１３１に当接する部位の曲率半径よりも大きく形成される。 先端 The tip surface 151 of the shaft of the bolt 150 is formed so as not to prevent the outer ring 141 from being deformed into an elliptical shape when the outer ring 141 is pressed by the bolt 150. In the present embodiment, the tip surface 151 of the shaft of the bolt 150 is formed in a flat shape. The inner peripheral surface of the housing hole 130 is formed so as not to hinder the outer ring 141 from being deformed into an elliptical shape when the outer ring 141 is pressed by the bolt 150. For example, the radius of curvature of the inner peripheral surface of the bottom portion 131 of the housing hole 130 is formed to be larger than the radius of curvature of a portion of the outer ring 141 deformed into an elliptical shape that comes into contact with the bottom portion 131.
　なお、楕円形状に変形した外輪１４１は、その揺動方向（Ｄ１）の両端部が収容孔１３０の内周面に接触していてもよいし、図示するように、接触してなくてもよい。少なくとも、第１軸受４に対して作用する直交方向（Ｄ２）の押圧力が、第１軸受４に対して作用する揺動方向（Ｄ１）の押圧力よりも大きくなるように、第１軸受４の外輪１４１が押圧される構成であればよい。 The outer ring 141 deformed into an elliptical shape may have both ends in the swing direction (D1) in contact with the inner peripheral surface of the housing hole 130, or may not be in contact as illustrated. . At least the first bearing 4 is set so that the pressing force acting on the first bearing 4 in the orthogonal direction (D2) is greater than the pressing force acting on the first bearing 4 in the swing direction (D1). The outer ring 141 may be configured to be pressed.
　ボルト１５０の軸部の直径が小さいと、外輪１４１の外周面の一部が局所的に変形してしまうおそれがある。このため、ボルト１５０の軸部の直径は、外輪１４１の外周面に対する押圧範囲を確保するために、例えば、外輪１４１の幅（軸方向（Ｄ３）の長さ）の１／２以上に設定することが好ましい。なお、ボルト１５０の軸部の直径を外輪１４１の幅よりも大きくすると、ギヤケース３が大型化し、コストの増加を招くおそれがあるため、ボルト１５０の直径は外輪１４１の幅未満に設定することが好ましい。また、ボルト１５０の直径を外輪１４１の幅未満とすることで、レイアウトの自由度も向上する。 If the diameter of the shaft of the bolt 150 is small, a part of the outer peripheral surface of the outer ring 141 may be locally deformed. For this reason, the diameter of the shaft portion of the bolt 150 is set to, for example, 幅 or more of the width (length in the axial direction (D3)) of the outer ring 141 in order to secure a pressing range against the outer peripheral surface of the outer ring 141. Is preferred. If the diameter of the shaft portion of the bolt 150 is larger than the width of the outer ring 141, the gear case 3 becomes large, which may increase the cost. Therefore, the diameter of the bolt 150 may be set to be smaller than the width of the outer ring 141. preferable. Further, by setting the diameter of the bolt 150 to be smaller than the width of the outer ring 141, the degree of freedom in layout is also improved.
　図６～図８を参照して、楕円形状に変形した第１軸受４の各部寸法及び内部隙間１４４について詳しく説明する。図６は、図７及び図８のＶＩ－ＶＩ線に沿う第１軸受４の内輪１４２と外輪１４１の断面模式図である。図６において、ボール１４３の図示は省略している。図７は、図６のＶＩＩ－ＶＩＩ線に沿う第１軸受４の断面模式図であり、図８は、図６のＶＩＩＩ－ＶＩＩＩ線に沿う第１軸受４の断面模式図である。図６～図８において、ボール１４３を保持する保持器の図示は省略している。なお、図６～図８において、第１軸受４の内輪１４２の内径は、図２及び図５に示すものに比べて小さく記載されている。また、図７において、内部隙間１４４は、誇張して大きく記載されている。 寸 法 With reference to FIGS. 6 to 8, the dimensions of each part of the first bearing 4 deformed into an elliptical shape and the internal gap 144 will be described in detail. FIG. 6 is a schematic cross-sectional view of the inner ring 142 and the outer ring 141 of the first bearing 4 along the line VI-VI in FIGS. 7 and 8. 6, illustration of the ball 143 is omitted. FIG. 7 is a schematic sectional view of the first bearing 4 along the line VII-VII in FIG. 6, and FIG. 8 is a schematic sectional view of the first bearing 4 along the line VIII-VIII in FIG. 6 to 8, illustration of a retainer that holds the ball 143 is omitted. 6 to 8, the inner diameter of the inner ring 142 of the first bearing 4 is shown smaller than those shown in FIGS. In FIG. 7, the internal gap 144 is exaggerated and enlarged.
　図６～図８に示すように、第１軸受４は、内側軌道溝１４２ａを有する内輪１４２と、外側軌道溝１４１ａを有する外輪１４１と、内側軌道溝１４２ａと外側軌道溝１４１ａとの間に配置される複数のボール１４３と、ボール１４３を保持する保持器（不図示）と、ウォームホイール１に向かうウォーム軸２の揺動を許容するための内部隙間１４４と、を有する。 As shown in FIGS. 6 to 8, the first bearing 4 is disposed between the inner race 142 having the inner race groove 142a, the outer race 141 having the outer race groove 141a, and the inner race groove 142a and the outer race groove 141a. A plurality of balls 143, a retainer (not shown) for holding the balls 143, and an internal gap 144 for allowing the worm shaft 2 to swing toward the worm wheel 1.
　外輪１４１は、ボルト１５０によって直交方向（Ｄ２）に押圧され、楕円形状に変形された状態で収容孔１３０内において保持される。外輪１４１の内周面を構成する外側軌道溝１４１ａは、ウォーム軸２の軸方向（Ｄ３）に直交する断面において、長軸の長さが２×Ｌａであり、短軸の長さが２×Ｌｂの楕円形状を呈する（Ｌａ＞Ｌｂ）。一方、内輪１４２の外周面である内側軌道溝１４２ａは、直径Ｄｏの円形状を呈する。 The outer ring 141 is pressed in the orthogonal direction (D2) by the bolt 150 and is held in the accommodation hole 130 in a state of being deformed into an elliptical shape. The outer raceway groove 141a that forms the inner peripheral surface of the outer ring 141 has a major axis length of 2 × La and a minor axis length of 2 × L in a cross section orthogonal to the axial direction (D3) of the worm shaft 2. It has an elliptical shape of Lb (La> Lb). On the other hand, the inner raceway groove 142a, which is the outer peripheral surface of the inner ring 142, has a circular shape with a diameter Do.
　このため、直交方向（Ｄ２）における内側軌道溝１４２ａと外側軌道溝１４１ａとの間の距離Ｌ１（＝Ｌｂ－Ｄｏ／２）は、揺動方向（Ｄ１）における内側軌道溝１４２ａと外側軌道溝１４１ａとの間の距離Ｌ２（＝Ｌａ－Ｄｏ／２）よりも小さい（Ｌ１＜Ｌ２）。 For this reason, the distance L1 (= Lb−Do / 2) between the inner raceway groove 142a and the outer raceway groove 141a in the orthogonal direction (D2) depends on the inner raceway groove 142a and the outer raceway groove 141a in the swing direction (D1). Is smaller than L2 (= La−Do / 2) (L1 <L2).
　外輪１４１が楕円形状に変形すると、内側軌道溝１４２ａと外側軌道溝１４１ａとの間の距離Ｌ２は、変形前に比べて大きくなる。このため、揺動方向（Ｄ１）における内部隙間１４４を変形前に比べて大きくすることができる。なお、揺動方向（Ｄ１）における内部隙間１４４の長さＸは、ウォーム軸２の揺動方向（Ｄ１）への揺動を許容し、効果的にウォーム２ａとウォームホイール１との間のバックラッシ（隙間）を低減できる長さに設定される。一方、距離Ｌ１は、直交方向（Ｄ２）における内部隙間１４４の長さが０あるいはほぼ０になるように、ボール１４３の外径と同じか、わずかに長くなるように設定される。このように、距離Ｌ１及び距離Ｌ２が設定されるので、直交方向（Ｄ２）における内部隙間１４４の長さは、揺動方向（Ｄ１）における内部隙間１４４の長さＸよりも小さくなる。 When the outer race 141 is deformed into an elliptical shape, the distance L2 between the inner raceway groove 142a and the outer raceway groove 141a becomes larger than before the deformation. Therefore, the internal gap 144 in the swing direction (D1) can be made larger than before the deformation. The length X of the internal gap 144 in the swing direction (D1) allows the worm shaft 2 to swing in the swing direction (D1), and effectively causes the backlash between the worm 2a and the worm wheel 1. (Gap) is set to a length that can be reduced. On the other hand, the distance L1 is set to be equal to or slightly longer than the outer diameter of the ball 143 so that the length of the internal gap 144 in the orthogonal direction (D2) is zero or almost zero. Since the distance L1 and the distance L2 are set as described above, the length of the internal gap 144 in the orthogonal direction (D2) is smaller than the length X of the internal gap 144 in the swing direction (D1).
　ボルト１５０は、挿通孔１３３内において直交方向（Ｄ２）に移動可能に設けられている。また、第１軸受４は、ボルト１５０のねじ込み量に応じて、直交方向（Ｄ２）における内側軌道溝１４２ａと外側軌道溝１４１ａとの距離Ｌ１が調整可能となるように構成されている。したがって、ボルト１５０のねじ込み量により、直交方向（Ｄ２）における第１軸受４の内部隙間１４４を容易に調整することができる。なお、直交方向（Ｄ２）における第１軸受４の内部隙間１４４の長さは、ギヤケース３に形成されるボルト１５０の受け座からボルト１５０の頭部の頂面までの距離、あるいは、ウォーム軸２に所定の荷重を付与させたときの揺動量を計測することにより管理することができる。なお、図５に示すように、所定の揺動量が得られるように、所定厚みのシム１５６をボルト１５０の頭部と、ギヤケース３に形成される受け座との間に介在させるようにしてもよい。 The bolt 150 is provided movably in the orthogonal direction (D2) in the insertion hole 133. Further, the first bearing 4 is configured such that the distance L1 between the inner raceway groove 142a and the outer raceway groove 141a in the orthogonal direction (D2) can be adjusted according to the screwing amount of the bolt 150. Therefore, the internal clearance 144 of the first bearing 4 in the orthogonal direction (D2) can be easily adjusted by the screwing amount of the bolt 150. The length of the internal clearance 144 of the first bearing 4 in the orthogonal direction (D2) is determined by the distance from the receiving seat of the bolt 150 formed in the gear case 3 to the top surface of the head of the bolt 150 or the worm shaft 2 Can be managed by measuring the amount of rocking when a predetermined load is applied to the. As shown in FIG. 5, a shim 156 having a predetermined thickness may be interposed between the head of the bolt 150 and a receiving seat formed on the gear case 3 so as to obtain a predetermined swing amount. Good.
　上述した実施形態によれば、次の作用効果を奏する。 According to the above-described embodiment, the following operation and effect can be obtained.
　（１）本実施形態に係るパワーステアリング装置１０に組み付けられる第１軸受４の外側軌道溝１４１ａは、揺動方向（Ｄ１）及びウォーム軸２の軸方向（Ｄ３）のそれぞれに直交する直交方向（Ｄ２）における内側軌道溝１４２ａと外側軌道溝１４１ａとの間の距離Ｌ１が、揺動方向（Ｄ１）における内側軌道溝１４２ａと外側軌道溝１４１ａとの間の距離Ｌ２よりも小さくなるように、楕円形状とされている。このため、揺動方向（Ｄ１）において第１軸受４の内部隙間１４４を確保しつつ、直交方向（Ｄ２）において第１軸受４の内部隙間１４４を揺動方向（Ｄ１）における内部隙間１４４よりも小さくすることができる。 (1) The outer raceway groove 141a of the first bearing 4 assembled to the power steering device 10 according to the present embodiment is orthogonal to the swing direction (D1) and the axial direction (D3) of the worm shaft 2 (D3). The ellipse is formed so that the distance L1 between the inner raceway groove 142a and the outer raceway groove 141a in D2) is smaller than the distance L2 between the inner raceway groove 142a and the outer raceway groove 141a in the swing direction (D1). It is shaped. For this reason, while securing the internal clearance 144 of the first bearing 4 in the swing direction (D1), the internal clearance 144 of the first bearing 4 in the orthogonal direction (D2) is larger than the internal clearance 144 in the swing direction (D1). Can be smaller.
　これにより、ウォーム軸２の揺動を許容しつつ、ウォーム軸２に軸方向（Ｄ３）の力が作用したときに、ウォーム軸２とともに内輪１４２が軸方向（Ｄ３）に移動することを抑制できる。その結果、ボール１４３が外輪１４１または内輪１４２と衝突することに起因した衝突音を低減することができ、減速機１００の騒音を低減することができる。したがって、本実施形態によれば、騒音の小さい減速機１００を備えたパワーステアリング装置１０を提供することができる。 This allows the inner ring 142 to move in the axial direction (D3) together with the worm shaft 2 when a force in the axial direction (D3) acts on the worm shaft 2 while allowing the worm shaft 2 to swing. . As a result, it is possible to reduce the collision sound caused by the ball 143 colliding with the outer ring 141 or the inner ring 142, and to reduce the noise of the speed reducer 100. Therefore, according to the present embodiment, it is possible to provide the power steering device 10 including the speed reducer 100 with low noise.
　なお、揺動方向（Ｄ１）における第１軸受４の内部隙間１４４は、十分に確保することができるので、ウォーム軸２の揺動角を大きくとることができる。このため、高温時のバックラッシ減少によるフリクションの増加、及び低温時及び耐久劣化後のバックラッシ増加による歯打ち音を効果的に抑制することができる。 In addition, since the internal clearance 144 of the first bearing 4 in the swing direction (D1) can be sufficiently ensured, the swing angle of the worm shaft 2 can be increased. For this reason, it is possible to effectively suppress an increase in friction due to a decrease in backlash at a high temperature and a rattling noise due to an increase in backlash at a low temperature and after durability deterioration.
　（２）第１軸受４の外輪１４１は、ボルト１５０及び収容孔１３０の底部１３１によって直交方向（Ｄ２）に押圧された状態で保持されることにより、直交方向（Ｄ２）における内側軌道溝１４２ａと外側軌道溝１４１ａとの間の距離Ｌ１が、揺動方向（Ｄ１）における内側軌道溝１４２ａと外側軌道溝１４１ａとの間の距離Ｌ２よりも小さくなるように変形している。円形状の外輪１４１を収容孔１３０に収容させた後、ボルト１５０によって外輪１４１を押圧し、楕円形状に変形させることにより、直交方向（Ｄ２）おける第１軸受４の内部隙間１４４を容易に小さくすることができる。したがって、本実施形態によれば、外輪１４１を予め楕円形状に形成しておく必要がないので、第１軸受４の製造コストを小さく抑えることができる。また、第１軸受４として、標準的な深溝玉軸受を用いることができるので、第１軸受４を容易に入手することができる。したがって、パワーステアリング装置１０のコストの低減を図ることができる。 (2) The outer race 141 of the first bearing 4 is held in a state of being pressed in the orthogonal direction (D2) by the bolts 150 and the bottom 131 of the receiving hole 130, so that the inner raceway groove 142a in the orthogonal direction (D2) The distance L1 between the outer raceway groove 141a and the outer raceway groove 141a is deformed to be smaller than the distance L2 between the inner raceway groove 142a and the outer raceway groove 141a in the swing direction (D1). After the circular outer ring 141 is accommodated in the accommodation hole 130, the outer ring 141 is pressed by the bolt 150 and deformed into an elliptical shape, so that the internal clearance 144 of the first bearing 4 in the orthogonal direction (D2) can be easily reduced. can do. Therefore, according to the present embodiment, since the outer ring 141 does not need to be formed in an elliptical shape in advance, the manufacturing cost of the first bearing 4 can be reduced. Further, since a standard deep groove ball bearing can be used as the first bearing 4, the first bearing 4 can be easily obtained. Therefore, the cost of the power steering device 10 can be reduced.
　（３）直交方向（Ｄ２）において、第１軸受４の内部隙間１４４を小さくできるので、直交方向（Ｄ２）におけるウォーム軸２のガタを防止することもできる。このため、ウォーム２ａがウォームホイール１に対して直交方向（Ｄ２）にずれた状態で噛み合うことを防止できる。 (3) Since the internal clearance 144 of the first bearing 4 can be reduced in the orthogonal direction (D2), it is possible to prevent the worm shaft 2 from rattling in the orthogonal direction (D2). Therefore, it is possible to prevent the worm 2a from meshing with the worm wheel 1 in a state of being shifted in the orthogonal direction (D2).
　＜第２実施形態＞
　図９から図１１を参照して、本発明の第２実施形態に係る減速機に用いられる押圧部について説明する。以下では、上記第１実施形態と異なる点を中心に説明し、図中、上記第１実施形態で説明した構成と同一の構成または相当する構成には同一の符号を付して説明を省略する。 <Second embodiment>
With reference to FIGS. 9 to 11, a pressing portion used in a speed reducer according to a second embodiment of the present invention will be described. In the following, description will be made focusing on points different from the first embodiment, and in the drawings, the same or corresponding components as those described in the first embodiment will be denoted by the same reference numerals and description thereof will be omitted. .
　上記第１実施形態では、ボルト１５０が、外輪１４１の外周を押圧する押圧部として機能する例について説明した。これに対して、本第２実施形態に係る減速機２００は、上記第１実施形態で説明したボルト１５０に代えて、押圧部として、環状の押圧リング２５０を備えている。 In the first embodiment, the example in which the bolt 150 functions as a pressing portion that presses the outer periphery of the outer ring 141 has been described. On the other hand, the speed reducer 200 according to the second embodiment includes an annular pressing ring 250 as a pressing portion instead of the bolt 150 described in the first embodiment.
　図９に示すように、減速機２００のギヤケース２０３には、第１軸受４を収容する収容孔２３０が形成されている。上記第１実施形態と同様、第１軸受４の外輪１４１は、ギヤケース２０３に形成された段部３ａとギヤケース２０３内に締結されたロックナット５との間で軸方向（Ｄ３）に挟持される。また、内輪１４２は、ウォーム軸２の段部２ｂとウォーム軸２の端部に圧入される軸連結器１９のウォーム側ジョイント９（図２参照）との間で軸方向（Ｄ３）に挟持される。 収容 As shown in FIG. 9, the gear case 203 of the speed reducer 200 is formed with a housing hole 230 for housing the first bearing 4. As in the first embodiment, the outer ring 141 of the first bearing 4 is held in the axial direction (D3) between the stepped portion 3a formed in the gear case 203 and the lock nut 5 fastened in the gear case 203. . Further, the inner race 142 is sandwiched in the axial direction (D3) between the stepped portion 2b of the worm shaft 2 and the worm-side joint 9 (see FIG. 2) of the shaft coupler 19 which is press-fitted into the end of the worm shaft 2. You.
　収容孔２３０は、第１軸受４の外輪１４１の外径よりも僅かに大きい内径を有する小径部２３０ａと、小径部２３０ａよりも内径が大きい大径部２３０ｂと、を有する。大径部２３０ｂには、押圧リング２５０が遊嵌される。 The housing hole 230 has a small diameter portion 230a having an inner diameter slightly larger than the outer diameter of the outer ring 141 of the first bearing 4, and a large diameter portion 230b having an inner diameter larger than the small diameter portion 230a. The pressing ring 250 is loosely fitted to the large diameter portion 230b.
　図１０に示すように、押圧リング２５０は、第１軸受４の外輪１４１が圧入される円環状の部材である。押圧リング２５０は、揺動方向（Ｄ１）の両端部２５０ａに、直交方向（Ｄ２）の両端部２５０ｂよりも剛性が低い低剛性部２５１が設けられる。低剛性部２５１は、径方向の幅が、他の部分（例えば、直交方向（Ｄ２）の両端部２５０ｂ）における径方向の幅よりも小さくなるように形成されている。つまり、低剛性部２５１は、その厚み（径方向の幅）が直交方向（Ｄ２）の両端部２５０ｂの厚み（径方向の幅）よりも薄い薄肉部である。 押 圧 As shown in FIG. 10, the pressing ring 250 is an annular member into which the outer ring 141 of the first bearing 4 is press-fitted. The pressing ring 250 is provided with low rigidity portions 251 having lower rigidity than both ends 250b in the orthogonal direction (D2) at both ends 250a in the swinging direction (D1). The low-rigidity portion 251 is formed such that the width in the radial direction is smaller than the width in the radial direction in another portion (for example, both ends 250b in the orthogonal direction (D2)). That is, the low-rigidity portion 251 is a thin portion whose thickness (radial width) is smaller than the thickness (radial width) of both ends 250b in the orthogonal direction (D2).
　なお、低剛性部２５１は、他の部分よりも剛性が低くなる部位であればよい。このため、他の部分と同じ厚み（径方向の幅）であっても、複数の溝や貫通孔を設けることにより低剛性部を形成してもよい。また、一対の半円弧状の部材の両端部同士を、半円弧状の部材よりも弾性率の低い部材で結合することにより押圧リングを形成してもよい。この場合、半円弧状の部材同士を結合する結合部材が低剛性部となる。このように、低剛性部２５１は、種々の形態を採用することができるが、本第２実施形態のように、他の部分よりも厚みの薄い薄肉部を低剛性部２５１とする場合、低剛性部２５１を容易に形成することができるので、減速機２００の製造コストの低減を図ることができる。 The low-rigidity portion 251 may be any portion that has lower rigidity than other portions. For this reason, even if it has the same thickness (radial width) as the other portions, the low-rigidity portion may be formed by providing a plurality of grooves or through holes. Alternatively, the pressing ring may be formed by joining both ends of a pair of semi-arc members with members having a lower elastic modulus than the semi-arc members. In this case, the connecting member that connects the semicircular arc-shaped members serves as a low rigidity portion. As described above, the low-rigidity portion 251 can adopt various forms. However, as in the second embodiment, when the low-rigidity portion 251 is a thin portion having a smaller thickness than other portions, the low-rigidity portion 251 has a low rigidity. Since the rigid portion 251 can be easily formed, the manufacturing cost of the speed reducer 200 can be reduced.
　本第２実施形態では、円環状のリング部材の外周に、一対の平坦な矩形状の面を形成することにより、低剛性部２５１が形成される。一対の低剛性部２５１の外周の平坦な面は、互いに平行に形成される。一対の低剛性部２５１の外周の平坦な面同士の揺動方向（Ｄ１）の間隔（二面幅）は、押圧リング２５０の外径よりも小さい。押圧リング２５０の内径は、第１軸受４の外輪１４１の外径よりも僅かに小さい径とされている。 In the second embodiment, the low-rigidity portion 251 is formed by forming a pair of flat rectangular surfaces on the outer periphery of the annular ring member. The outer flat surfaces of the pair of low rigidity portions 251 are formed parallel to each other. The interval (two-plane width) in the swing direction (D1) between the outer flat surfaces of the pair of low-rigidity portions 251 is smaller than the outer diameter of the pressing ring 250. The inner diameter of the pressing ring 250 is slightly smaller than the outer diameter of the outer ring 141 of the first bearing 4.
　押圧リング２５０に一対の低剛性部２５１が設けられているため、押圧リング２５０の内周に第１軸受４の外輪１４１を圧入すると、図１１において実線で示すように、押圧リング２５０の内周が楕円形状となるように、押圧リング２５０が変形する。これは、低剛性部２５１が他の部分（例えば、直交方向の両端部２５０ｂ）よりも剛性が低く、変形しやすいためである。 Since the pressing ring 250 is provided with a pair of low-rigid portions 251, when the outer ring 141 of the first bearing 4 is press-fitted into the inner circumference of the pressing ring 250, as shown by a solid line in FIG. The pressing ring 250 is deformed so that the shape becomes elliptical. This is because the low rigidity portion 251 has lower rigidity than other portions (for example, both ends 250b in the orthogonal direction) and is easily deformed.
　第１軸受４の外輪１４１は、押圧リング２５０に圧入されると、その全周に亘って押圧リング２５０から押圧力を受けることになる。押圧リング２５０の内周が楕円形状に変形することに伴い、第１軸受４の外輪１４１における直交方向（Ｄ２）の両端部には、第１軸受４の外輪１４１における揺動方向（Ｄ１）の両端部に作用する押圧力よりも大きい押圧力が作用する。 When the outer ring 141 of the first bearing 4 is press-fitted into the pressing ring 250, the outer ring 141 receives a pressing force from the pressing ring 250 over the entire circumference. As the inner circumference of the pressing ring 250 is deformed into an elliptical shape, both ends of the outer ring 141 of the first bearing 4 in the orthogonal direction (D2) are provided at both ends in the swing direction (D1) of the outer ring 141 of the first bearing 4. A pressing force greater than the pressing force applied to both ends acts.
　換言すれば、押圧リング２５０は、第１軸受４に対する直交方向（Ｄ２）の押圧力が、第１軸受４に対する揺動方向（Ｄ１）の押圧力よりも大きくなるように、第１軸受４の外輪１４１を押圧する。このため、押圧リング２５０の内周が楕円形状に変形することに伴って、第１軸受４の外輪１４１も楕円形状に変形する。 In other words, the pressing ring 250 acts on the first bearing 4 so that the pressing force in the orthogonal direction (D2) against the first bearing 4 is larger than the pressing force in the swing direction (D1) on the first bearing 4. The outer ring 141 is pressed. Therefore, as the inner circumference of the pressing ring 250 is deformed into an elliptical shape, the outer ring 141 of the first bearing 4 is also deformed into an elliptical shape.
　図１１では、変形前の押圧リング２５０を二点鎖線で示している。図１１に示すように、変形後の押圧リング２５０の揺動方向（Ｄ１）の両端部２５０ａ間の距離は、変形前に比べて大きくなる。つまり、押圧リング２５０は、外輪１４１が圧入されることにより揺動方向（Ｄ１）に伸長する。一方、変形後の押圧リング２５０の直交方向（Ｄ２）の両端部２５０ｂ間の距離は、変形前に比べて小さくなる。つまり、押圧リング２５０は、外輪１４１が圧入されることにより直交方向（Ｄ２）に圧縮される。 In FIG. 11, the pressing ring 250 before deformation is indicated by a two-dot chain line. As shown in FIG. 11, the distance between both ends 250a in the swinging direction (D1) of the pressing ring 250 after the deformation is larger than before the deformation. That is, the press ring 250 extends in the swing direction (D1) when the outer ring 141 is press-fitted. On the other hand, the distance between both ends 250b of the pressing ring 250 in the orthogonal direction (D2) after the deformation is smaller than before. That is, the press ring 250 is compressed in the orthogonal direction (D2) by press-fitting the outer ring 141.
　押圧リング２５０が直交方向（Ｄ２）に圧縮されるため、外輪１４１も直交方向（Ｄ２）に圧縮される。また、押圧リング２５０が揺動方向（Ｄ１）に伸長するため、外輪１４１も揺動方向（Ｄ１）に伸長する。 た め Since the pressing ring 250 is compressed in the orthogonal direction (D2), the outer ring 141 is also compressed in the orthogonal direction (D2). Further, since the pressing ring 250 extends in the swing direction (D1), the outer ring 141 also extends in the swing direction (D1).
　なお、図９に示すように、押圧リング２５０の軸方向の幅Ｗ１は、外輪１４１の軸方向の幅Ｗ２よりも小さい（Ｗ１＜Ｗ２）。押圧リング２５０は、小径部２３０ａと大径部２３０ｂと間に形成される段差とロックナット５との間で挟持されることにより、その位置が規定される。第１軸受４は、一端部が押圧リング２５０から軸方向（Ｄ３）に突出しており、第１軸受４の突出部４ａが収容孔２３０の小径部２３０ａに嵌め込まれる。なお、第１軸受４の突出部４ａと、収容孔２３０の小径部２３０ａとのはめあいは、「すきまばめ」である。突出部４ａには、押圧リング２５０の内周が接触していない。つまり、突出部４ａは、押圧リング２５０から直接押圧力を受けない部位である。これにより、押圧リング２５０の押圧力による突出部４ａの変形が抑制されるので、突出部４ａを収容孔２３０の小径部２３０ａに「すきまばめ」により、嵌入させることができる。 As shown in FIG. 9, the axial width W1 of the pressing ring 250 is smaller than the axial width W2 of the outer ring 141 (W1 <W2). The position of the pressing ring 250 is defined by being clamped between a step formed between the small diameter portion 230a and the large diameter portion 230b and the lock nut 5. One end of the first bearing 4 protrudes from the pressing ring 250 in the axial direction (D3), and the protruding portion 4a of the first bearing 4 is fitted into the small-diameter portion 230a of the accommodation hole 230. The fit between the projecting portion 4a of the first bearing 4 and the small-diameter portion 230a of the housing hole 230 is "clearance fit". The inner circumference of the pressing ring 250 is not in contact with the protrusion 4a. That is, the protruding portion 4 a is a portion that does not receive the pressing force directly from the pressing ring 250. Thereby, the deformation of the protruding portion 4a due to the pressing force of the pressing ring 250 is suppressed, so that the protruding portion 4a can be fitted into the small-diameter portion 230a of the accommodation hole 230 by “clear fit”.
　このように、本第２実施形態では、第１軸受４を円環状の押圧リング２５０に圧入することにより、第１軸受４の外輪１４１を直交方向（Ｄ２）に圧縮させることができる。したがって、上記第１実施形態と同様、直交方向（Ｄ２）における内側軌道溝１４２ａと外側軌道溝１４１ａとの間の距離Ｌ１が、揺動方向（Ｄ１）における内側軌道溝１４２ａと外側軌道溝１４１ａとの間の距離Ｌ２よりも小さくなるように、第１軸受４を変形させることができる（図６～図８参照）。したがって、第２実施形態によれば、第１実施形態と同様の作用効果を奏する。 As described above, in the second embodiment, by pressing the first bearing 4 into the annular pressing ring 250, the outer ring 141 of the first bearing 4 can be compressed in the orthogonal direction (D2). Therefore, similarly to the first embodiment, the distance L1 between the inner raceway groove 142a and the outer raceway groove 141a in the orthogonal direction (D2) is equal to the distance L1 between the inner raceway groove 142a and the outer raceway groove 141a in the swing direction (D1). The first bearing 4 can be deformed so as to be smaller than the distance L2 between the two (see FIGS. 6 to 8). Therefore, according to the second embodiment, the same operation and effect as those of the first embodiment can be obtained.
　また、低剛性部２５１の剛性により、第１軸受４の直交方向（Ｄ２）の圧縮量を設定することができる。その結果、直交方向（Ｄ２）における第１軸受４の内部隙間１４４を適切に設定することができる。 Further, the compression amount of the first bearing 4 in the orthogonal direction (D2) can be set by the rigidity of the low rigidity portion 251. As a result, the internal clearance 144 of the first bearing 4 in the orthogonal direction (D2) can be appropriately set.
　次のような変形例も本発明の範囲内であり、変形例に示す構成と上述の実施形態で説明した構成を組み合わせたり、以下の異なる変形例で説明する構成同士を組み合わせたりすることも可能である。 The following modified examples are also within the scope of the present invention, and it is also possible to combine the configuration described in the modified example with the configuration described in the above embodiment, or to combine the configurations described in the following different modified examples. It is.
　＜変形例１＞
　上記第１実施形態では、ボルト１５０を直接、外輪１４１に接触させて、外輪１４１に荷重を付与し、外側軌道溝１４１ａを楕円形状に変形させる例について説明したが、本発明はこれに限定されない。ボルト１５０と外輪１４１との間に、スペーサを介在させてもよい。この場合、ボルト１５０は、スペーサを介して外輪１４１を押圧し、外輪１４１を楕円形状に変形させる。本変形例では、外輪１４１の外周に接触するスペーサの端面を平面状に形成することにより、外輪１４１をスムーズに変形させることができる。このため、ボルト１５０の先端面１５１は、平面状に形成する必要がない。 <Modification 1>
In the above-described first embodiment, an example has been described in which the bolt 150 is brought into direct contact with the outer ring 141 to apply a load to the outer ring 141 and deform the outer raceway groove 141a into an elliptical shape. However, the present invention is not limited to this. . A spacer may be interposed between the bolt 150 and the outer ring 141. In this case, the bolt 150 presses the outer ring 141 via the spacer to deform the outer ring 141 into an elliptical shape. In the present modification, the outer ring 141 can be smoothly deformed by forming the end surface of the spacer that comes into contact with the outer periphery of the outer ring 141 into a flat shape. For this reason, it is not necessary to form the tip end surface 151 of the bolt 150 in a planar shape.
　＜変形例２＞
　上記第１実施形態では、ボルト１５０が、外輪１４１を押圧する押圧部として機能する例について説明したが、本発明はこれに限定されない。例えば、ギヤケース３において、収容孔１３０に臨む上下一対の貫通孔を形成し、貫通孔に挿通される一対の押圧部を有するクランプ等により、外輪１４１を上下から挟むようにしてもよい。この場合、クランプ等によって、外輪１４１の外周面の上部及び下部のそれぞれに押圧力を付与することで、外輪１４１を楕円形状に変形させる。 <Modification 2>
In the first embodiment, the example in which the bolt 150 functions as a pressing portion that presses the outer ring 141 has been described, but the present invention is not limited to this. For example, in the gear case 3, a pair of upper and lower through holes facing the housing hole 130 may be formed, and the outer ring 141 may be sandwiched from above and below by a clamp having a pair of pressing portions inserted into the through hole. In this case, the outer ring 141 is deformed into an elliptical shape by applying a pressing force to each of the upper and lower portions of the outer peripheral surface of the outer ring 141 by a clamp or the like.
　＜変形例３＞
　上記第１実施形態では、円形状の外輪１４１を収容孔１３０に収容させた後、ボルト１５０の押圧力により外輪１４１を楕円形状に変形させる例について説明し、上記第２実施形態では、押圧リング２５０に外輪１４１を圧入することにより外輪１４１を楕円形状に変形させる例について説明したが、本発明はこれに限定されない。 <Modification 3>
In the first embodiment described above, an example is described in which the outer ring 141 is deformed into an elliptical shape by the pressing force of the bolt 150 after the outer ring 141 having a circular shape is accommodated in the accommodation hole 130. The example in which the outer ring 141 is deformed into an elliptical shape by press-fitting the outer ring 141 into the 250 has been described, but the present invention is not limited to this.
　例えば、図１２に示すように、第１軸受４を収容する収容孔３３０に押圧部を形成してもよい。図１２に示す例では、収容孔３３０は、第１軸受４の外輪１４１における直交方向（Ｄ２）の両端部が圧入嵌合される一対の嵌合面３５０と、第１軸受４の外輪１４１の第１方向の両端部に対向して配置され嵌合面３５０から径方向外方に窪む凹部３５３と、を有する。 For example, as shown in FIG. 12, a pressing portion may be formed in the receiving hole 330 that receives the first bearing 4. In the example shown in FIG. 12, the housing hole 330 is formed between a pair of fitting surfaces 350 on both ends of the outer ring 141 of the first bearing 4 in the orthogonal direction (D2) by press-fitting, and the outer ring 141 of the first bearing 4. A concave portion 353 that is disposed to face both ends in the first direction and that is depressed radially outward from the fitting surface 350.
　一対の嵌合面３５０は、円弧状の面であり、その内径は第１軸受４の外輪１４１の外径よりも僅かに小さい。このため、第１軸受４の外輪１４１を収容孔３３０に圧入すると、外輪１４１の外周が、一対の嵌合面３５０によって押圧される。つまり、本変形例では、一対の嵌合面３５０が、第１軸受４の外輪１４１の外周を押圧する押圧部として機能する。凹部３５３の深さは、第１軸受４の外輪１４１が楕円形状に変形することを妨げないように、十分な深さに設定されている。なお、本変形例では、凹部３５３の底面と外輪１４１とは接触しない。つまり、凹部３５３に対向する外輪１４１の外周には押圧力が作用しない。 The pair of fitting surfaces 350 are arc-shaped surfaces, and the inner diameter thereof is slightly smaller than the outer diameter of the outer ring 141 of the first bearing 4. Therefore, when the outer ring 141 of the first bearing 4 is press-fitted into the accommodation hole 330, the outer periphery of the outer ring 141 is pressed by the pair of fitting surfaces 350. That is, in the present modification, the pair of fitting surfaces 350 function as a pressing portion that presses the outer periphery of the outer ring 141 of the first bearing 4. The depth of the recess 353 is set to a sufficient depth so as not to prevent the outer ring 141 of the first bearing 4 from being deformed into an elliptical shape. In this modification, the bottom surface of the recess 353 does not contact the outer ring 141. That is, no pressing force acts on the outer periphery of the outer ring 141 facing the recess 353.
　本変形例では、一対の嵌合面３５０が、第１軸受４に対する直交方向（Ｄ２）の押圧力が第１軸受４に対する揺動方向（Ｄ１）の押圧力（本変形例では、第１方向（Ｄ１）の押圧力は０（ゼロ））よりも大きくなるように、第１軸受４の外輪１４１を押圧する。 In the present modification, the pair of fitting surfaces 350 is such that the pressing force in the orthogonal direction (D2) against the first bearing 4 is the pressing force in the swing direction (D1) against the first bearing 4 (in this modification, the first direction). The outer ring 141 of the first bearing 4 is pressed so that the pressing force of (D1) is larger than 0 (zero).
　このように、本変形例では、上記実施形態と同様、揺動方向（Ｄ１）において第１軸受４の内部隙間１４４を確保しつつ、直交方向（Ｄ２）において第１軸受４の内部隙間１４４を揺動方向（Ｄ１）における内部隙間１４４よりも小さくすることができる。これにより、ウォーム軸２の揺動を許容しつつ、ウォーム軸２に軸方向の力が作用したときに、ウォーム軸２とともに内輪１４２が軸方向に移動することを抑制できる。その結果、ボール１４３が外輪１４１または内輪１４２と衝突することに起因した衝突音を低減することができ、減速機の騒音を低減することができる。また、嵌合面３５０に凹部３５３が設けられた簡素な構成であるので、減速機の製造コストの低減を図ることができる。 As described above, in the present modified example, similarly to the above-described embodiment, the internal gap 144 of the first bearing 4 is secured in the orthogonal direction (D2) while the internal gap 144 of the first bearing 4 is secured in the swing direction (D1). It can be smaller than the internal gap 144 in the swing direction (D1). This allows the inner ring 142 to move in the axial direction together with the worm shaft 2 when an axial force acts on the worm shaft 2 while allowing the worm shaft 2 to swing. As a result, it is possible to reduce the collision noise caused by the ball 143 colliding with the outer ring 141 or the inner ring 142, and reduce the noise of the speed reducer. In addition, since the fitting surface 350 has a simple configuration in which the concave portion 353 is provided, it is possible to reduce the manufacturing cost of the speed reducer.
　なお、収容孔３３０に押圧部を設ける例は、本変形例に限定されない。例えば、収容孔１３０を楕円形状に形成し、円形状の外輪１４１を収容孔１３０に圧入することにより、外輪１４１の外周及び外側軌道溝１４１ａを楕円形状に変形させてもよい。また、収容孔１３０を円形状に形成し、楕円形状の外輪１４１を収容孔１３０に圧入することにより、外輪１４１の外周を円形状に変形させるとともに、外輪１４１の外側軌道溝１４１ａを楕円形状に変形させてもよい。この場合、収容孔１３０における外輪１４１との当接部が、外輪１４１を変形させる押圧部として機能する。収容孔１３０の形状によって、外輪１４１を上記実施形態と同様に変形できる場合、ボルト１５０や押圧リング２５０等の押圧部材を省略することができる。つまり、収容孔３３０に押圧部を形成する場合、収容孔３３０に形成される押圧部により、第１軸受４の外輪１４１を第２方向（Ｄ２）に押圧するため、ギヤケース３とは別に押圧部を設ける場合に比べて部品点数を低減することができる。 The example in which the pressing portion is provided in the housing hole 330 is not limited to this modified example. For example, the outer periphery of the outer ring 141 and the outer raceway groove 141a may be deformed into an elliptical shape by forming the accommodation hole 130 into an elliptical shape and press-fitting the circular outer ring 141 into the accommodation hole 130. Further, by forming the accommodation hole 130 in a circular shape and pressing the elliptical outer ring 141 into the accommodation hole 130, the outer periphery of the outer ring 141 is deformed into a circular shape, and the outer raceway groove 141a of the outer ring 141 is formed into an elliptical shape. It may be deformed. In this case, the contact portion of the housing hole 130 with the outer ring 141 functions as a pressing portion that deforms the outer ring 141. When the outer ring 141 can be deformed in the same manner as in the above embodiment depending on the shape of the housing hole 130, pressing members such as the bolt 150 and the pressing ring 250 can be omitted. That is, when the pressing portion is formed in the receiving hole 330, the pressing portion formed in the receiving hole 330 presses the outer ring 141 of the first bearing 4 in the second direction (D2). The number of parts can be reduced as compared with the case of providing.
　＜変形例４＞
　上記実施形態では、円形状の外輪１４１に押圧力を付与して、外側軌道溝１４１ａを楕円形状にする例について説明したが、本発明はこれに限定されない。予め、楕円形状の外側軌道溝１４１ａを有する外輪１４１を収容孔１３０に固定させてもよい。例えば、外周の両側を押圧することにより楕円形状に変形させた円板に、円形状の軌道溝を形成した後、押圧力を除去することにより、外側軌道溝１４１ａを楕円形状とすることができる。本変形例では、予め、第１軸受４に楕円形状の外側軌道溝１４１ａが形成されているので、ボルト１５０を省略することができる。なお、外側軌道溝１４１ａが楕円形状であればよいので、外形形状は任意の形状とすることができる。例えば、外輪１４１の外形形状は、円形状とすることができる。この場合、外輪１４１を収容孔１３０に容易に位置決めできるように、外輪１４１の側面に目印を設けることが好ましい。さらに、収容孔１３０に対して外輪１４１が回転することを防止する位置決め部（互いに嵌合する凹凸等）を設けることが好ましい。 <Modification 4>
In the above-described embodiment, an example has been described in which the pressing force is applied to the circular outer ring 141 to make the outer raceway groove 141a elliptical, but the present invention is not limited to this. The outer race 141 having the elliptical outer raceway groove 141a may be fixed to the housing hole 130 in advance. For example, after forming a circular raceway groove on a disk deformed into an elliptical shape by pressing both sides of the outer periphery, the outer raceway groove 141a can be made elliptical by removing the pressing force. . In this modified example, the elliptical outer raceway groove 141a is formed in the first bearing 4 in advance, so that the bolt 150 can be omitted. Since the outer raceway groove 141a only needs to have an elliptical shape, the outer shape can be any shape. For example, the outer shape of the outer ring 141 can be circular. In this case, it is preferable to provide a mark on the side surface of the outer ring 141 so that the outer ring 141 can be easily positioned in the accommodation hole 130. Further, it is preferable to provide a positioning portion (an uneven portion or the like fitted to each other) for preventing the outer ring 141 from rotating with respect to the accommodation hole 130.
　＜変形例５＞
　上記実施形態では、第１軸受４の内輪１４２をウォーム軸２に圧入することにより固定する例について説明したが、本発明はこれに限定されない。ウォーム軸２に対して第１軸受４の内輪１４２をすきまばめにより嵌合し、かしめにより第１軸受４のウォーム軸２に対する回り止めを行うことにより、内輪１４２をウォーム軸２に固定してもよい。 <Modification 5>
In the above embodiment, the example in which the inner ring 142 of the first bearing 4 is fixed by press-fitting the worm shaft 2 has been described, but the present invention is not limited to this. The inner ring 142 of the first bearing 4 is fitted to the worm shaft 2 by loose fit, and the inner bearing 142 is fixed to the worm shaft 2 by caulking to prevent the first bearing 4 from rotating with respect to the worm shaft 2. Is also good.
　＜変形例６＞
　上記実施形態では、第１軸受４の外輪１４１の外側軌道溝１４１ａが楕円形状とされる例について説明したが、本発明はこれに限定されない。外側軌道溝１４１ａは、連続した曲面として形成されていればよい。少なくとも、直交方向（Ｄ２）における内側軌道溝１４２ａと外側軌道溝１４１ａとの間の距離Ｌ１が、揺動方向（Ｄ１）における内側軌道溝１４２ａと外側軌道溝１４１ａとの間の距離Ｌ２よりも小さくなればよい。 <Modification 6>
In the above-described embodiment, an example in which the outer raceway groove 141a of the outer ring 141 of the first bearing 4 has an elliptical shape has been described, but the present invention is not limited to this. The outer raceway groove 141a may be formed as a continuous curved surface. At least, the distance L1 between the inner raceway groove 142a and the outer raceway groove 141a in the orthogonal direction (D2) is smaller than the distance L2 between the inner raceway groove 142a and the outer raceway groove 141a in the swing direction (D1). I just need to be.
　＜変形例７＞
　上記実施形態では、第１軸受４が深溝玉軸受である例について説明したが、本発明はこれに限定されない。第１軸受４は、少なくとも玉軸受であればよく、自動調心玉軸受またはアンギュラ玉軸受であってもよい。 <Variation 7>
In the above embodiment, the example in which the first bearing 4 is a deep groove ball bearing has been described, but the present invention is not limited to this. The first bearing 4 may be at least a ball bearing, and may be a self-aligning ball bearing or an angular ball bearing.
　＜変形例８＞
　上記実施形態では、駆動歯車としてのウォーム２ａと、従動歯車としてのウォームホイール１と、を有するウォームギヤを減速機１００として用いる例について説明したが、本発明はこれに限定されない。駆動歯車としてのハイポイドピニオンと、従動歯車としてのハイポイドホイールと、を有するハイポイドギヤを減速機として用いてもよい。また、ベベルギヤを減速機として用いてもよい。 <Modification 8>
In the above embodiment, an example was described in which the worm gear having the worm 2a as the drive gear and the worm wheel 1 as the driven gear was used as the speed reducer 100, but the present invention is not limited to this. A hypoid gear having a hypoid pinion as a driving gear and a hypoid wheel as a driven gear may be used as a reduction gear. Further, a bevel gear may be used as a speed reducer.
　＜変形例９＞
　上記実施形態では、パワーステアリング装置１０の減速機１００に本発明を適用する例について説明したが、コンベア、ウィンチ、工作機械、建設機械等、種々の機械の減速機に本発明を適用することができる。 <Modification 9>
In the above embodiment, an example in which the present invention is applied to the speed reducer 100 of the power steering device 10 has been described. However, the present invention is applicable to various types of speed reducers such as a conveyor, a winch, a machine tool, and a construction machine. it can.
　以上のように構成された本発明の実施形態の構成、作用、および効果をまとめて説明する。 構成 The configuration, operation, and effect of the embodiment of the present invention configured as described above will be described together.
　減速機１００，２００は、駆動源（電動モータ７）に連結された駆動歯車軸（ウォーム軸２）と、駆動歯車軸（ウォーム軸２）に噛み合う従動歯車（ウォームホイール１）とを備えた減速機であって、駆動歯車軸（ウォーム軸２）の基端側を回転自在に支持する第１軸受４と、駆動歯車軸（ウォーム軸２）の先端側を回転自在に支持する第２軸受１１と、第２軸受１１を介して、駆動歯車軸（ウォーム軸２）を従動歯車（ウォームホイール１）へ向けて付勢する付勢部材（コイルスプリング１２）と、を備え、第１軸受４は、内側軌道溝１４２ａを有する内輪１４２と、外側軌道溝１４１ａを有する外輪１４１と、内側軌道溝１４２ａと外側軌道溝１４１ａとの間に配置される複数の転動体（ボール１４３）と、を有し、駆動歯車軸（ウォーム軸２）が揺動する方向である第１方向（Ｄ１）及び駆動歯車軸（ウォーム軸２）の軸方向（Ｄ３）のそれぞれに直交する第２方向（Ｄ２）における内側軌道溝１４２ａと外側軌道溝１４１ａとの間の距離Ｌ１が、第１方向（Ｄ１）における内側軌道溝１４２ａと外側軌道溝１４１ａとの間の距離Ｌ２よりも小さい。 The reduction gears 100 and 200 each include a drive gear shaft (worm shaft 2) connected to a drive source (electric motor 7) and a driven gear (worm wheel 1) that meshes with the drive gear shaft (worm shaft 2). A first bearing 4 rotatably supporting a base end side of a drive gear shaft (worm shaft 2) and a second bearing 11 rotatably supporting a distal end side of the drive gear shaft (worm shaft 2). And a biasing member (coil spring 12) for biasing the drive gear shaft (worm shaft 2) toward the driven gear (worm wheel 1) via the second bearing 11; , An inner race 142 having an inner race groove 142a, an outer race 141 having an outer race groove 141a, and a plurality of rolling elements (balls 143) arranged between the inner race groove 142a and the outer race groove 141a. , Drive gear shaft (W The inner raceway groove 142a and the outer raceway in a second direction (D2) orthogonal to the first direction (D1) in which the shaft 2) swings and the axial direction (D3) of the drive gear shaft (worm shaft 2). The distance L1 between the raceway groove 141a and the distance L2 between the inner raceway groove 142a and the outer raceway groove 141a in the first direction (D1) is smaller.
　この構成では、第１方向（Ｄ１）において第１軸受４の内部隙間１４４を確保しつつ、第２方向（Ｄ２）において第１軸受４の内部隙間１４４を第１方向（Ｄ１）における内部隙間１４４よりも小さくすることができる。これにより、駆動歯車軸（ウォーム軸２）の揺動を許容しつつ、駆動歯車軸（ウォーム軸２）に軸方向の力が作用したときに、駆動歯車軸（ウォーム軸２）とともに内輪１４２が軸方向に移動することを抑制できる。その結果、転動体（ボール１４３）が外輪１４１または内輪１４２と衝突することに起因した衝突音を低減することができ、減速機１００，２００の騒音を低減することができる。 In this configuration, the internal clearance 144 of the first bearing 4 is secured in the second direction (D2) while the internal clearance 144 of the first bearing 4 is secured in the first direction (D1). Can be smaller than Thus, when an axial force acts on the drive gear shaft (worm shaft 2) while allowing the swing of the drive gear shaft (worm shaft 2), the inner ring 142 is formed together with the drive gear shaft (worm shaft 2). Movement in the axial direction can be suppressed. As a result, it is possible to reduce the collision noise caused by the rolling element (ball 143) colliding with the outer ring 141 or the inner ring 142, and reduce the noise of the reduction gears 100 and 200.
　減速機１００，２００は、第１軸受４の外輪１４１を第２方向（Ｄ２）に押圧する押圧部（底部１３１、ボルト１５０、押圧リング２５０、嵌合面３５０）をさらに備え、第１軸受４の外輪１４１は、押圧部（底部１３１、ボルト１５０、押圧リング２５０、嵌合面３５０）によって押圧された状態で保持されることにより、第２方向（Ｄ２）における内側軌道溝１４２ａと外側軌道溝１４１ａとの間の距離Ｌ１が、第１方向（Ｄ１）における内側軌道溝１４２ａと外側軌道溝１４１ａとの間の距離Ｌ２よりも小さくなるように変形している。 The reduction gears 100 and 200 further include a pressing portion (a bottom portion 131, a bolt 150, a pressing ring 250, and a fitting surface 350) that presses the outer ring 141 of the first bearing 4 in the second direction (D2). The outer race 141 is held in a state where it is pressed by the pressing portions (the bottom 131, the bolt 150, the pressing ring 250, the fitting surface 350), so that the inner raceway groove 142a and the outer raceway groove in the second direction (D2). The distance L1 between the outer raceway 141a and the inner raceway groove 142a is smaller than the distance L2 between the inner raceway groove 142a and the outer raceway groove 141a in the first direction (D1).
　この構成では、押圧部（底部１３１、ボルト１５０、押圧リング２５０、嵌合面３５０）によって外輪１４１を変形させることにより、第２方向（Ｄ２）における第１軸受４の内部隙間１４４を容易に小さくすることができる。 In this configuration, the inner space 144 of the first bearing 4 in the second direction (D2) can be easily reduced by deforming the outer ring 141 by the pressing portion (the bottom 131, the bolt 150, the pressing ring 250, the fitting surface 350). can do.
　減速機１００，２００は、駆動源（電動モータ７）に連結された駆動歯車軸（ウォーム軸２）と、駆動歯車軸（ウォーム軸２）に噛み合う従動歯車（ウォームホイール１）とを備えた減速機であって、駆動歯車軸（ウォーム軸２）の基端側を回転自在に支持する第１軸受４と、駆動歯車軸（ウォーム軸２）の先端側を回転自在に支持する第２軸受１１と、第２軸受１１を介して、駆動歯車軸（ウォーム軸２）を従動歯車（ウォームホイール１）へ向けて付勢する付勢部材（コイルスプリング１２）と、第１軸受４の外周を押圧する押圧部（底部１３１、ボルト１５０、押圧リング２５０、嵌合面３５０）と、を備え、第１軸受４は、内側軌道溝１４２ａを有する内輪１４２と、外側軌道溝１４１ａを有する外輪１４１と、内側軌道溝１４２ａと外側軌道溝１４１ａとの間に配置される複数の転動体（ボール１４３）と、を有し、押圧部（底部１３１、ボルト１５０、押圧リング２５０、嵌合面３５０）は、駆動歯車軸（ウォーム軸２）が揺動する方向を第１方向（Ｄ１）とし、第１方向（Ｄ１）及び駆動歯車軸（ウォーム軸２）の軸方向（Ｄ３）のそれぞれに直交する方向を第２方向（Ｄ２）としたとき、第１軸受４に対する第２方向（Ｄ２）の押圧力が、第１軸受４に対する第１方向（Ｄ１）の押圧力よりも大きくなるように、第１軸受４の外輪１４１を押圧する。 The reduction gears 100 and 200 each include a drive gear shaft (worm shaft 2) connected to a drive source (electric motor 7) and a driven gear (worm wheel 1) that meshes with the drive gear shaft (worm shaft 2). A first bearing 4 rotatably supporting a base end side of a drive gear shaft (worm shaft 2) and a second bearing 11 rotatably supporting a distal end side of the drive gear shaft (worm shaft 2). And an urging member (coil spring 12) for urging the drive gear shaft (worm shaft 2) toward the driven gear (worm wheel 1) via the second bearing 11, and presses the outer periphery of the first bearing 4. The first bearing 4 includes an inner race 142 having an inner raceway groove 142a and an outer racer 141 having an outer raceway groove 141a, and a pressing portion (bottom 131, bolt 150, pressing ring 250, fitting surface 350). Inner track groove 142 And a plurality of rolling elements (balls 143) disposed between the outer raceway groove 141a and the outer raceway groove 141a. The pressing portion (the bottom portion 131, the bolt 150, the pressing ring 250, and the fitting surface 350) includes a driving gear shaft ( The direction in which the worm shaft 2) swings is defined as a first direction (D1), and the direction orthogonal to each of the first direction (D1) and the axial direction (D3) of the drive gear shaft (worm shaft 2) is defined as a second direction (D1). D2), the outer ring 141 of the first bearing 4 such that the pressing force on the first bearing 4 in the second direction (D2) is greater than the pressing force on the first bearing 4 in the first direction (D1). Press.
　この構成では、第１方向（Ｄ１）において第１軸受４の内部隙間１４４を確保しつつ、第２方向（Ｄ２）において第１軸受４の内部隙間１４４を第１方向（Ｄ１）における内部隙間１４４よりも小さくすることができる。これにより、駆動歯車軸（ウォーム軸２）の揺動を許容しつつ、駆動歯車軸（ウォーム軸２）に軸方向の力が作用したときに、駆動歯車軸（ウォーム軸２）とともに内輪１４２が軸方向に移動することを抑制できる。その結果、転動体（ボール１４３）が外輪１４１または内輪１４２と衝突することに起因した衝突音を低減することができ、減速機１００，２００の騒音を低減することができる。 In this configuration, the internal clearance 144 of the first bearing 4 is secured in the second direction (D2) while the internal clearance 144 of the first bearing 4 is secured in the first direction (D1). Can be smaller than Thus, when an axial force acts on the drive gear shaft (worm shaft 2) while allowing the swing of the drive gear shaft (worm shaft 2), the inner ring 142 is formed together with the drive gear shaft (worm shaft 2). Movement in the axial direction can be suppressed. As a result, it is possible to reduce the collision noise caused by the rolling element (ball 143) colliding with the outer ring 141 or the inner ring 142, and reduce the noise of the reduction gears 100 and 200.
　減速機１００は、押圧部が、第２方向（Ｄ２）に移動可能なボルト１５０であり、第１軸受４が、ボルト１５０のねじ込み量に応じて、第２方向（Ｄ２）における内側軌道溝１４２ａと外側軌道溝１４１ａとの間の距離Ｌ１が調整可能となるように構成される。 In the speed reducer 100, the pressing portion is a bolt 150 that is movable in the second direction (D2), and the first bearing 4 is configured such that the first bearing 4 moves the inner raceway groove 142a in the second direction (D2) in accordance with the screwing amount of the bolt 150. The distance L1 between the outer raceway groove 141a and the outer raceway groove 141a is configured to be adjustable.
　この構成では、ボルト１５０のねじ込み量により、第２方向（Ｄ２）における第１軸受４の内部隙間１４４を容易に調整することができる。 In this configuration, the internal clearance 144 of the first bearing 4 in the second direction (D2) can be easily adjusted by the screwing amount of the bolt 150.
　減速機２００は、押圧部が、第１軸受４の外輪１４１が圧入される環状の部材（押圧リング２５０）であり、第１方向（Ｄ１）の両端部２５０ａに、第２方向（Ｄ２）の両端部２５０ｂよりも剛性が低い低剛性部２５１が設けられる。 In the speed reducer 200, the pressing portion is an annular member (pressing ring 250) into which the outer ring 141 of the first bearing 4 is press-fitted, and is provided at both ends 250 a in the first direction (D 1) in the second direction (D 2). A low-rigidity portion 251 having lower rigidity than both ends 250b is provided.
　この構成では、第１軸受４を環状の押圧部（押圧リング２５０）に圧入することにより、第１軸受４の外輪１４１を第２方向（Ｄ２）に圧縮させることができ、その圧縮量を、低剛性部２５１の剛性により設定することができる。 In this configuration, the outer ring 141 of the first bearing 4 can be compressed in the second direction (D2) by press-fitting the first bearing 4 into the annular pressing portion (the pressing ring 250). It can be set by the rigidity of the low rigidity portion 251.
　減速機２００は、低剛性部２５１が、第２方向（Ｄ２）の両端部２５０ｂの厚みよりも薄い薄肉部である。 In the speed reducer 200, the low-rigidity portion 251 is a thin portion that is thinner than the thickness of both ends 250b in the second direction (D2).
　この構成では、低剛性部２５１を容易に形成することができるので、減速機２００の製造コストの低減を図ることができる。 In this configuration, since the low-rigidity portion 251 can be easily formed, the manufacturing cost of the reduction gear 200 can be reduced.
　減速機１００，２００は、駆動歯車軸（ウォーム軸２）を収容するケース（ギヤケース３，２０３）をさらに備え、ケース（ギヤケース３，２０３）には、第１軸受４を収容する収容孔１３０，３３０が形成され、押圧部（底部１３１、嵌合面３５０）が、収容孔１３０，３３０に形成される。 The reduction gears 100 and 200 further include a case (gear case 3, 203) for accommodating the drive gear shaft (worm shaft 2), and the case (gear case 3, 203) has an accommodation hole 130, for accommodating the first bearing 4. 330 is formed, and the pressing portion (the bottom portion 131, the fitting surface 350) is formed in the receiving holes 130 and 330.
　この構成では、収容孔１３０，３３０に形成される押圧部（底部１３１、嵌合面３５０）により、第１軸受４の外輪１４１を第２方向（Ｄ２）に押圧するため、ケース（ギヤケース３，２０３）とは別に押圧部を設ける場合に比べて部品点数を低減することができる。 In this configuration, the outer ring 141 of the first bearing 4 is pressed in the second direction (D2) by the pressing portions (the bottom portion 131, the fitting surface 350) formed in the receiving holes 130 and 330. The number of parts can be reduced as compared with the case where a pressing portion is provided separately from 203).
　減速機１００，２００は、収容孔３３０が、第１軸受４の外輪１４１の第２方向（Ｄ２）の両端部が圧入嵌合される一対の嵌合面３５０と、第１軸受４の外輪１４１の第１方向（Ｄ１）の両端部に対向して配置され嵌合面３５０から径方向外方に窪む凹部３５３と、を有し、一対の嵌合面３５０が、外輪１４１を押圧する押圧部である。 In the reduction gears 100 and 200, the housing hole 330 has a pair of fitting surfaces 350 into which both ends of the outer ring 141 of the first bearing 4 in the second direction (D2) are press-fitted, and the outer ring 141 of the first bearing 4. And a recess 353 which is disposed opposite to both ends in the first direction (D1) and is depressed radially outward from the fitting surface 350. The pair of fitting surfaces 350 presses the outer ring 141. Department.
　この構成では、嵌合面３５０に凹部３５３が設けられた簡素な構成であるので、減速機１００，２００の製造コストの低減を図ることができる。 In this configuration, since the fitting surface 350 has a simple configuration in which the concave portion 353 is provided, the manufacturing cost of the reduction gears 100 and 200 can be reduced.
　パワーステアリング装置１０は、上記減速機１００と、駆動源としての電動モータ７と、を備え、従動歯車（ウォームホイール１）は、車輪６を転舵するラック軸８に電動モータ７の回転力を伝達する出力軸２２に設けられ、減速機１００は、駆動歯車軸（ウォーム軸２）の回転を減速して、従動歯車（ウォームホイール１）に伝達する。 The power steering device 10 includes the speed reducer 100 and an electric motor 7 as a drive source. A driven gear (worm wheel 1) applies a torque of the electric motor 7 to a rack shaft 8 that steers the wheels 6. The reduction gear 100 is provided on the output shaft 22 for transmission, and reduces the rotation of the drive gear shaft (worm shaft 2) and transmits the rotation to the driven gear (worm wheel 1).
　この構成では、騒音の小さい上記減速機１００を備えたパワーステアリング装置１０を提供することができる。 With this configuration, it is possible to provide the power steering device 10 including the above-described speed reducer 100 with low noise.
　以上、本発明の実施形態について説明したが、上記実施形態は本発明の適用例の一部を示したに過ぎず、本発明の技術的範囲を上記実施形態の具体的構成に限定する趣旨ではない。 As described above, the embodiment of the present invention has been described. However, the above embodiment is only a part of an application example of the present invention, and the technical scope of the present invention is not limited to the specific configuration of the above embodiment. Absent.
　本願は２０１８年６月２８日に日本国特許庁に出願された特願２０１８－１２３０４７に基づく優先権を主張し、この出願の全ての内容は参照により本明細書に組み込まれる。 This application claims the priority based on Japanese Patent Application No. 2018-123047 filed with the Japan Patent Office on June 28, 2018, the entire contents of which are incorporated herein by reference.

Claims (9)

  1. 　駆動源に連結された駆動歯車軸と、前記駆動歯車軸に噛み合う従動歯車とを備えた減速機であって、
    　前記駆動歯車軸の基端側を回転自在に支持する第１軸受と、
    　前記駆動歯車軸の先端側を回転自在に支持する第２軸受と、
    　前記第２軸受を介して、前記駆動歯車軸を前記従動歯車へ向けて付勢する付勢部材と、を備え、
    　前記第１軸受は、
    　内側軌道溝を有する内輪と、
    　外側軌道溝を有する外輪と、
    　前記内側軌道溝と前記外側軌道溝との間に配置される複数の転動体と、を有し、
    　前記駆動歯車軸が揺動する方向である第１方向及び前記駆動歯車軸の軸方向のそれぞれに直交する第２方向における前記内側軌道溝と前記外側軌道溝との間の距離が、前記第１方向における前記内側軌道溝と前記外側軌道溝との間の距離よりも小さい、減速機。     A reduction gear comprising a drive gear shaft connected to a drive source and a driven gear meshing with the drive gear shaft,
    A first bearing rotatably supporting a base end side of the drive gear shaft;
    A second bearing rotatably supporting the distal end side of the drive gear shaft;
    An urging member that urges the drive gear shaft toward the driven gear via the second bearing;
    The first bearing includes:
    An inner ring having an inner raceway,
    An outer ring having an outer raceway,
    A plurality of rolling elements disposed between the inner raceway groove and the outer raceway groove,
    The distance between the inner raceway groove and the outer raceway groove in a first direction that is a direction in which the drive gear shaft swings and a second direction orthogonal to each of the axial directions of the drive gear shaft is the first direction. A speed reducer that is smaller than the distance between the inner raceway groove and the outer raceway groove in a direction.
  2. 　請求項１に記載の減速機であって、
    　前記第１軸受の前記外輪を前記第２方向に押圧する押圧部をさらに備え、
    　前記第１軸受の前記外輪は、前記押圧部によって押圧された状態で保持されることにより、前記第２方向における前記内側軌道溝と前記外側軌道溝との間の距離が、前記第１方向における前記内側軌道溝と前記外側軌道溝との間の距離よりも小さくなるように変形している、減速機。     The speed reducer according to claim 1, wherein
    A pressing portion that presses the outer ring of the first bearing in the second direction;
    The outer race of the first bearing is held in a state pressed by the pressing portion, so that a distance between the inner raceway groove and the outer raceway groove in the second direction is increased in the first direction. A speed reducer deformed to be smaller than a distance between the inner raceway groove and the outer raceway groove.
  3. 　駆動源に連結された駆動歯車軸と、前記駆動歯車軸に噛み合う従動歯車とを備えた減速機であって、
    　前記駆動歯車軸の基端側を回転自在に支持する第１軸受と、
    　前記駆動歯車軸の先端側を回転自在に支持する第２軸受と、
    　前記第２軸受を介して、前記駆動歯車軸を前記従動歯車へ向けて付勢する付勢部材と、
    　前記第１軸受の外周を押圧する押圧部と、を備え、
    　前記第１軸受は、
    　内側軌道溝を有する内輪と、
    　外側軌道溝を有する外輪と、
    　前記内側軌道溝と前記外側軌道溝との間に配置される複数の転動体と、を有し、
    　前記押圧部は、前記駆動歯車軸が揺動する方向を第１方向とし、前記第１方向及び前記駆動歯車軸の軸方向のそれぞれに直交する方向を第２方向としたとき、前記第１軸受に対する前記第２方向の押圧力が、前記第１軸受に対する前記第１方向の押圧力よりも大きくなるように、前記第１軸受の前記外輪を押圧する、減速機。     A reduction gear comprising a drive gear shaft connected to a drive source and a driven gear meshing with the drive gear shaft,
    A first bearing rotatably supporting a base end side of the drive gear shaft;
    A second bearing rotatably supporting the distal end side of the drive gear shaft;
    An urging member for urging the drive gear shaft toward the driven gear via the second bearing;
    A pressing portion for pressing the outer periphery of the first bearing,
    The first bearing includes:
    An inner ring having an inner raceway,
    An outer ring having an outer raceway,
    A plurality of rolling elements disposed between the inner raceway groove and the outer raceway groove,
    The pressing portion is configured such that, when a direction in which the drive gear shaft swings is a first direction, and a direction orthogonal to each of the first direction and the axial direction of the drive gear shaft is a second direction, the first bearing. A pressure reducer that presses the outer ring of the first bearing so that a pressing force in the second direction on the first bearing is greater than a pressing force on the first bearing in the first direction.
  4. 　請求項２に記載の減速機であって、
    　前記押圧部は、前記第２方向に移動可能なボルトであり、
    　前記第１軸受は、前記ボルトのねじ込み量に応じて、前記第２方向における前記内側軌道溝と前記外側軌道溝との間の距離が調整可能となるように構成される、減速機。     The speed reducer according to claim 2,
    The pressing portion is a bolt that is movable in the second direction,
    The speed reducer, wherein the first bearing is configured such that a distance between the inner raceway groove and the outer raceway groove in the second direction can be adjusted according to a screwing amount of the bolt.
  5. 　請求項２に記載の減速機であって、
    　前記押圧部は、前記第１軸受の前記外輪が圧入される環状の部材であり、前記第１方向の両端部に、前記第２方向の両端部よりも剛性が低い低剛性部が設けられる、減速機。     The speed reducer according to claim 2,
    The pressing portion is an annular member into which the outer ring of the first bearing is press-fitted, and a low-rigidity portion having lower rigidity than both ends in the second direction is provided at both ends in the first direction. Decelerator.
  6. 　請求項５に記載の減速機であって、
    　前記低剛性部は、前記第２方向の両端部の厚みよりも薄い薄肉部である、減速機。     The speed reducer according to claim 5, wherein
    The speed reducer, wherein the low-rigidity portion is a thin-walled portion that is thinner than both end portions in the second direction.
  7. 　請求項２に記載の減速機であって、
    　前記駆動歯車軸を収容するケースをさらに備え、
    　前記ケースには、前記第１軸受を収容する収容孔が形成され、
    　前記押圧部は、前記収容孔に形成される、減速機。     The speed reducer according to claim 2,
    Further comprising a case for housing the drive gear shaft,
    An accommodation hole for accommodating the first bearing is formed in the case,
    The speed reducer, wherein the pressing portion is formed in the accommodation hole.
  8. 　請求項７に記載の減速機であって、
    　前記収容孔は、
    　前記第１軸受の前記外輪の前記第２方向の両端部が圧入嵌合される一対の嵌合面と、
    　前記第１軸受の前記外輪の前記第１方向の両端部に対向して配置され前記嵌合面から径方向外方に窪む凹部と、を有し、
    　前記一対の嵌合面が、前記外輪を押圧する前記押圧部である、減速機。     The speed reducer according to claim 7, wherein
    The accommodation hole,
    A pair of fitting surfaces into which both ends of the outer ring of the first bearing in the second direction are press-fitted;
    A concave portion arranged opposite to both ends of the outer ring of the first bearing in the first direction and recessed radially outward from the fitting surface;
    The speed reducer, wherein the pair of fitting surfaces is the pressing portion that presses the outer ring.
  9. 　請求項１に記載の減速機と、
    　前記駆動源としての電動モータと、を備え、
    　前記従動歯車は、車輪を転舵するラック軸に前記電動モータの回転力を伝達する出力軸に設けられ、
    　前記減速機は、前記駆動歯車軸の回転を減速して、前記従動歯車に伝達する、パワーステアリング装置。     A speed reducer according to claim 1,
    An electric motor as the drive source,
    The driven gear is provided on an output shaft that transmits the torque of the electric motor to a rack shaft that steers wheels,
    The power steering device, wherein the speed reducer reduces the rotation of the drive gear shaft and transmits the rotation to the driven gear.
PCT/JP2019/023278 2018-06-28 2019-06-12 Reducer and power steering device WO2020004037A1 (en)

Applications Claiming Priority (2)

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JP2018123047 2018-06-28
JP2018-123047 2018-06-28

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Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20100140011A1 (en) * 2006-11-04 2010-06-10 Mark Anthony Wilkes Worm gear for electric assisted steering apparatus and method controlling the movement of the worm shaft in a worm gearing

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20100140011A1 (en) * 2006-11-04 2010-06-10 Mark Anthony Wilkes Worm gear for electric assisted steering apparatus and method controlling the movement of the worm shaft in a worm gearing

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