CN116221310A

CN116221310A - Vibration isolator

Info

Publication number: CN116221310A
Application number: CN202111473278.7A
Authority: CN
Inventors: 伊藤优歩; 井上敏郎
Original assignee: Honda Motor Co Ltd
Current assignee: Honda Motor Co Ltd
Priority date: 2021-12-02
Filing date: 2021-12-02
Publication date: 2023-06-06

Abstract

The invention provides a vibration isolator capable of providing a larger current to a magnetorheological elastomer of a bushing assembly, so as to correspondingly increase the magnetic flux density in the magnetorheological elastomer of the bushing assembly according to the current provided to the bushing assembly, and further obtain larger rigidity change. The vibration isolator is mountable to a vehicle and includes: a variable stiffness bushing assembly; and a collar member made of a magnetic material; the variable stiffness bushing assembly has: an inner cylinder which is made of a magnetic material and has a hollow shaft portion for fastening to the vehicle; an outer tube made of a magnetic material and disposed coaxially with the inner tube on the outer side in the radial direction of the inner tube; a magnetorheological elastomer disposed between the inner cylinder and the outer cylinder; and a coil for applying a magnetic field that changes the viscoelasticity of the magnetorheological elastomer, wherein the collar member is in contact with an axial end of the inner tube of the variable stiffness bushing assembly.

Description

Vibration isolator

Technical Field

The present invention relates to a vibration isolator, and more particularly to a vibration isolator for mounting on a frame of a vehicle.

Background

In recent years, construction safety cities and human living areas have been enhanced in all countries to enhance the inclusive and sustainable urban construction, sustainable human living area planning and management capabilities of all countries. There is therefore a need in all countries to enhance the provision of safe, affordable, easy to use, sustainable transportation systems for all people, to improve road safety, in particular to expand public transportation, and to pay particular attention to the needs of people with fragile conditions, women, children, disabled persons and the elderly. In the traffic field, measures are urgently needed to cope with environmental problems to develop technologies capable of improving convenience and traffic safety of public transportation.

In the related art vehicle manufacturing industry, a vehicle vibration isolation device (also referred to as a vibration isolation noise reduction device) is disclosed to suppress transmission of vibrations generated by a driving force distribution device supported by a subframe and inputs (vibration forces) from a road surface to a vehicle body side. For example, patent document 1 discloses a mount using a magnetorheological elastomer, which is disposed on a subframe to which a driving source of a vehicle is mounted. Patent document 1 discloses a technique for improving the cornering performance of a vehicle by improving the rigidity (yaw stiffness) of a mount by improving the elastic modulus of a magnetorheological elastomer when a vehicle turns with a large torque difference between left and right wheels. Patent document 2 describes a direction of a change in rigidity due to a magnetic field of a magnetorheological elastomer.

In the related art, a mount and a magnetorheological elastomer are provided on a sub-frame of a portion of a sub-frame of a vehicle supported by a vehicle body (main frame) so that elastic forces (resistance forces) applied to the mount in respective directions with respect to forces applied from a plurality of directions can be adjusted. Accordingly, although it has been proposed in the prior art to use a magnetorheological elastomer to enable the elastic force of the mount to be varied for each application direction, there is no discussion in the prior art about how to increase the magnetic flux density inside the magnetorheological elastomer.

Further, patent document 3 discloses a fastening system for fastening a bush unit to a vehicle frame, in which an inner tube of the bush unit is brought into contact with a fastened portion of the vehicle frame.

[ Prior Art literature ]

[ patent literature ]

Patent document 1 Japanese patent application laid-open No. 6047087

[ patent document 2] International publication No. 2016/148011

Patent document 3 Japanese patent laid-open publication No. 2020-133700

Disclosure of Invention

[ problem to be solved by the invention ]

Accordingly, in the related art (patent document 3 described above), in order to make it possible to change the elastic force of the mount in each application direction, a bush assembly having a magnetorheological elastomer is used to mount the mount on the vehicle frame. However, in such a fixing method, only the inner tube of the bush assembly is in contact with the fixed portion of the vehicle frame. Therefore, in the prior art, since the cross-sectional area of a magnetic circuit (magnetic circuit) that can be generated by the bushing assembly is fixed, the increase of the cross-sectional area is limited in such a fixed structure, and thus the increase of the magnetic flux density in the magnetorheological elastomer is limited.

The present invention has been made in view of the above-described circumstances, and an object of the present invention is to provide a vibration isolator that can be mounted on a vehicle, and that can supply a larger current to a magnetorheological elastomer of a bushing assembly, so as to increase the magnetic flux density in the interior of the magnetorheological elastomer of the bushing assembly in accordance with the current supplied to the bushing assembly, and that can achieve a larger change in rigidity.

[ means of solving the problems ]

In order to achieve the above object, the present invention is a vibration isolator mountable to a vehicle, the vibration isolator including: a variable stiffness bushing assembly; and a collar member made of a magnetic material; the variable stiffness bushing assembly has: an inner cylinder which is made of a magnetic material and has a hollow shaft portion for fastening to the vehicle; an outer tube made of a magnetic material and disposed coaxially with the inner tube on the outer side in the radial direction of the inner tube; a magnetorheological elastomer disposed between the inner cylinder and the outer cylinder; and a coil for applying a magnetic field that changes the viscoelasticity of the magnetorheological elastomer, wherein the collar member is in contact with an axial end of the inner tube of the variable stiffness bushing assembly.

By disposing the collar member made of a magnetic material at the axial end of the inner tube and in contact with the axial end of the inner tube in this manner, a larger current can be passed through the variable stiffness bushing assembly to increase the magnetic flux density of the magnetorheological elastomer of the variable stiffness bushing assembly, and a larger change in stiffness can be obtained.

In an embodiment of the present invention, the vibration isolator further includes: and a fastened member made of a magnetic material, wherein the collar member is in contact with the fastened member.

In this way, by re-superimposing the amount of increased cross-sectional area of the fastened member, a larger amplitude of rigidity variation can be obtained.

In one embodiment of the present invention, the fastened member has a through hole coaxial with the hollow shaft portion, and the collar member is in contact with an inner surface of the through hole.

In this way, by increasing the contact area between the collar member and the fastened member, the cross-sectional area of the magnetic circuit can be increased.

In an embodiment of the present invention, the variable stiffness bushing assembly, the collar member and the fastened member are fastened by a fastening element composed of a magnetic body.

In this way, by further superimposing the amount of the increased cross-sectional area of the fastening element made of the magnetic material, the cross-sectional area of the magnetic circuit can be increased.

In one embodiment of the present invention, the collar member is disposed in the through hole of the fastened member in a press-fit manner.

In this way, by pressing the collar member into the through hole of the fastened member, the collar member and the fastened member can be brought into firm contact.

In one embodiment of the present invention, an outer diameter of an inner ring portion of the collar member that contacts the inner cylinder is larger than an outer diameter of the inner cylinder.

In this way, the cross-sectional area of the magnetic circuit between the collar member and the fastened member can be ensured to the maximum.

In one embodiment of the invention, the vibration isolator is used for a bushing of a suspension arm of a vehicle.

In this way, by disposing the vibration isolator in the bushing of the suspension arm of the vehicle, the rigidity of the bushing of the suspension arm can be made variable, and therefore the vehicle can be made compatible with both the ride quality performance and the vibration noise performance, wherein the rigidity can be improved when the ride quality performance is required, and the rigidity can be reduced when the vibration noise performance is required, and thus the vibration isolator capable of combining both the ride quality performance and the vibration noise performance can be provided.

[ Effect of the invention ]

As described above, in the vibration isolator according to the present invention, by disposing the collar member made of the magnetic material at the axial end portion of the inner tube and in contact with the axial end portion of the inner tube, a larger current can be passed through the variable stiffness bushing assembly, so that the magnetic flux density of the magnetorheological elastomer of the variable stiffness bushing assembly can be increased, and a larger stiffness change can be obtained. Further, by grounding the collar member made of a magnetic material to the inner tube that generates the magnetic circuit, the cross-sectional area of the magnetic circuit in the coil can be increased, and the amount of the cross-sectional area increased by the magnetic circuit in the coil is the amount of the cross-sectional area increased by providing the collar member. Accordingly, the value of the applied current when the saturated magnetic flux density is reached on the cross section of the magnetic circuit in the coil becomes large, and thus a larger change in rigidity can be obtained. Further, the amount of the cross-sectional area of the magnetic circuit can be conveniently adjusted by the shape of the collar member, and the magnetic flux density inside the magnetorheological elastomer can be increased to obtain a larger rigidity change.

In order to make the above features and advantages of the present invention more comprehensible, embodiments accompanied with figures are described in detail below.

Drawings

Fig. 1 is a partially omitted cross-sectional view schematically showing that a vibration isolator according to an embodiment of the present invention is fastened to a vehicle frame.

Fig. 2A is a schematic diagram showing a state of a magnetorheological elastomer structure of a basic structure in the case where an external force in a shearing direction is not applied.

Fig. 2B is a schematic view showing a state of the magnetorheological elastomer structure of the basic structure which is deflected in the lateral direction by an external force applied in the shearing direction.

Fig. 2C is a schematic diagram showing a state in which the resistance increases in the magnetorheological elastomer structure of the basic structure when a magnetic field in the vertical direction is applied.

Reference numerals illustrate:

1: vibration isolator

110: variable stiffness bushing assembly

112: outer cylinder

112E: axial end

112H: hollow shaft portion

114: inner cylinder

116: magnetorheological elastomer

118: coil

120: collar member

120E: outer ring part

120I: inner ring part

130: fastened component

130H: through hole

140: fastening element

140B: bolt

140N: nut

Detailed Description

Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the embodiments described below, when referring to the number, amount, and the like, the scope of the present invention is not necessarily limited to the number, amount, and the like unless specifically described. In the following embodiments, each constituent element is not necessarily essential to the present invention unless otherwise specified. In the following, when a plurality of embodiments are present, the characteristic portions of each embodiment can be appropriately combined, unless otherwise specified, from the beginning.

Hereinafter, a vibration isolator for a mount for mounting on a sub-frame according to the present invention will be described in detail with reference to the drawings, by taking a preferred embodiment as an example.

Fig. 1 is a partially omitted cross-sectional view schematically showing that a vibration isolator according to an embodiment of the present invention is fastened to a vehicle frame. Fig. 1 is a schematic view of a part of a vibration isolator, which is fastened to a sub-frame, for example, by a mount to a vehicle body (e.g., a main frame). Referring to fig. 1, the vibration isolator 1 of the present invention may be mounted on a mounting seat of a vehicle, and a sub-frame of the vehicle may be coupled with a main frame via the mounting seat. The steering wheel of the vehicle is coupled to and suspended from the main frame and the sub-frame by a suspension device (not shown), and is coupled to a steering wheel (not shown) via a rack mechanism and a steering shaft.

Here, first, before explaining the structure and the operational effects of the vibration isolator 1 according to the present embodiment, the operational effects of the basic structure magnetorheological elastomer structure (structure of the magnetorheological elastomer (MRE: magnetic Rheological Elastomer) 116 described below) 100 will be described with reference to fig. 2A, 2B, and 2C for the sake of easy understanding. Fig. 2A is a schematic diagram showing a state of a magnetorheological elastomer structure of a basic structure in the case where an external force in a shearing direction is not applied. Fig. 2B is a schematic view showing a state of the magnetorheological elastomer structure of the basic structure which is deflected in the lateral direction by an external force applied in the shearing direction. Fig. 2C is a schematic diagram showing a state in which the resistance increases in the magnetorheological elastomer structure of the basic structure when a magnetic field (magnetic field) in the vertical direction is applied.

Fig. 2A shows a state of the magnetorheological elastomer structure 100 in the case where an external force (shear stress) in the shear direction is not applied. In the magnetorheological elastomer structure 100 in fig. 2A, a magnetorheological elastomer 108 in which an elastomer 106 is cured is disposed between an upper support 101 and a lower support 102, and the elastomer 106 is a silicone rubber or the like having magnetic particles oriented in the up-down direction, for example, iron powder 104.

As shown in fig. 2B, for example, when an external force in the shearing direction is applied to the upper support 101 in a state where the lower support 102 is fixed to a base (not shown), the magnetorheological elastic member 108 deflects in the lateral direction to which the external force in the shearing direction is applied. In this case, the elastic body 106 generates a resistance force against an external force in the shearing direction to be restored to the original shape.

As shown in fig. 2C, when a magnetic flux (magnetic field) indicated by a broken line arrow in the up-down direction is applied at this time, resistance in a direction indicated by a short arrow to return the iron powder 104 to a direction coincident with the magnetic flux direction increases. The resistance indicated by the short arrow from right to left increases on the upper side of the magnetorheological elastomer structure 100, and the resistance indicated by the arrow from left to right increases on the lower side of the magnetorheological elastomer structure 100. The larger the magnitude of the magnetic field, the larger the value of the resistance. In this way, in the magnetorheological elastomer structure 100, the resistance against the external force in the shearing direction can be changed (changed) according to the magnitude of the applied magnetic field.

Accordingly, for example, in the mount to which the vibration isolation device 1 of the present invention is attached, the greater the yaw rate obtained by the yaw rate sensor and the greater the vehicle speed obtained by the vehicle speed sensor, the greater the coil exciting current of the coil (coil) is controlled by the control device of the vehicle, not shown, whereby the resistance of the mount, that is, the elasticity of the mount can be fixed (variable). Therefore, for example, when traveling on a straight road or cruising on a highway, the coil exciting current is set to a zero value or a smaller value by the control device of the vehicle, so that the elasticity of the mount is softened, the forced vibration input from the internal combustion engine or the motor is cut off, and in addition, the vibration input transmitted from the road surface to the main frame via the suspension can be blocked, and as a result, the sound and vibration felt by the passenger in the vehicle cabin can be suppressed, and the comfort can be improved. On the other hand, in a so-called curved road or a winding road, the vehicle control device increases the coil exciting current to fix (change) the elasticity of the mount, thereby improving the vehicle's running performance (cornering performance) and the driver's drivability (steering stability).

In the vibration isolator 1 according to the embodiment of the present invention, in order to be able to supply a larger current to the magnetorheological elastomer, the magnetic flux density (magnetic flux density) in the magnetorheological elastomer is increased correspondingly to the supplied current, so that a larger rigidity change is obtained. Referring to fig. 1, the vibration isolator 1 includes a variable stiffness bushing assembly 110 and a collar member 120. The variable stiffness bushing assembly 110 is comprised of a cylindrical inner barrel 112, a cylindrical outer barrel 114, a magnetorheological elastomer 116, and a coil 118. The inner tube 112 is made of a magnetic material (magnet), and has a hollow shaft portion 112H for fastening to a vehicle. The outer tube 114 is made of a magnetic material, and is disposed coaxially with the inner tube 112 on the outer side in the radial direction of the inner tube 112. The magnetorheological elastomer 116 is disposed between the inner barrel 112 and the outer barrel 114. The coil 118 applies a magnetic field that changes the viscoelasticity of the magnetorheological elastomer 116. The collar member 120 is in contact with the axial end 112E of the inner tube 112 of the variable stiffness bushing assembly 110.

A cylindrical coil (exciting coil) 118 is housed in a side wall of the cylindrical inner tube 112, and the coil 118 generates a magnetic field having a strength corresponding to the magnitude of a coil exciting current supplied from a control unit (ECU: electronic Control Unit) (not shown) of the vehicle. A magnetorheological elastomer 116 is held between the inner barrel 112 and the outer barrel 114. Magnetorheological elastomer 116 is a component whose viscoelastic properties vary according to the magnitude of the magnetic field generated by field coil 118. Specifically, the magnetorheological elastomer 116 is made of an elastic material such as a rubber material to which magnetic powder such as iron powder is added, and has a property that the rigidity is low in a state where the magnetic field generated by the coil 118 is not present (or in a state where the magnetic field is low), and the rigidity is high in a state where the magnetic field generated by the coil 118 is present, depending on the magnitude of the magnetic field.

As described above, as shown in fig. 1, by disposing the collar member 120 made of a magnetic material at the axial end 112E of the inner tube 112 and in contact with the axial end 112E of the inner tube 112, a larger current can be passed through the variable stiffness bushing assembly 110 to increase the magnetic flux density of the magnetorheological elastomer 116 of the variable stiffness bushing assembly 110, and a larger change in stiffness can be obtained.

Further, by grounding the collar member 120 made of a magnetic material to the inner tube 112 that is a magnetic circuit, the cross-sectional area of the magnetic circuit in the coil 118 can be increased, and the amount of the cross-sectional area increased by the magnetic circuit in the coil 118 is the amount of the cross-sectional area increased by providing the collar member 120. Accordingly, the value of the applied current when the saturated magnetic flux density is reached in the cross section of the magnetic circuit in the coil 112 becomes large, and thus a larger change in rigidity can be obtained. Further, the amount of cross-sectional area of the magnetic circuit can be conveniently adjusted by the shape of the collar member 120, and the magnetic flux density inside the magnetorheological elastomer 116 can be raised to obtain a larger rigidity change.

Referring to fig. 1, in the vibration isolator 1 of the present embodiment, collar members 120 are provided at both ends in the axial direction of the variable stiffness bushing assembly 110, and the collar members 120 are in contact with the axial direction end 112E of the inner tube 112 and also in contact with the fastening portion of the vehicle body (i.e., fastened member 130). The collar member 120 is located between the axial end 112E of the inner tube 112 and the fastened member 130. The fastened member 130 contacting the collar member 120 is made of a magnetic material. More specifically, as shown in fig. 1, the fastened member 130 has a through hole 130H coaxial with the hollow shaft portion 112H of the inner tube 112, and the collar member 120 is in contact with the inner surface of the through hole 130H. In this way, by further superimposing the increased amount of the cross-sectional area of the fastened member 130 made of the magnetic material, a larger amplitude of the rigidity change can be obtained. In other words, by increasing the contact area between the collar member 120 and the fastened member 130, the cross-sectional area of the magnetic circuit generated also increases.

In the present embodiment, the variable stiffness bushing assembly 110, the collar member 120, and the fastened member 130 are fastened by the fastening element 140 made of a magnetic material. As shown in fig. 1, the fastening element 140 is constituted by, for example, a bolt (bolt) 140B and a nut (nut) 140N, and fastening between the variable stiffness bushing assembly 110, the collar member 120, and the fastened member 130 is performed using the fastening element 140 constituted by a magnetic body in the present embodiment. In this way, by further superimposing the amount of the increased cross-sectional area of the fastening element 140 made of a magnetic material, the cross-sectional area of the magnetic circuit can be increased, and thus the magnetic flux density becomes high, and the amplitude of the rigidity change increases.

The collar member 120 in the present embodiment is provided by press fitting, that is, the collar member 120 is pressed into the through hole 130H of the fastened member 130. By pressing the collar member 120 into the through-hole 130H of the fastened member 130 in this manner, the collar member 120 and the fastened member 130 can be brought into firm contact.

In the present embodiment, as shown in fig. 1, the collar member 120 is configured to have an inner ring portion 120I and an outer ring portion 120E having different outer diameter sizes, wherein the inner ring portion 120I of the collar member 120 is in contact with the inner cylinder 112 and the outer ring portion 120E is in contact with the through hole 130H of the fastened member 130. Accordingly, since the collar member 120 is disposed between the axial end portion 112E of the inner tube 112 and the fastened member 130 in a press-fit manner, as shown in fig. 1, the side surface of the inner ring portion 120I of the collar member 120 can be surely brought into close contact with the side surface of the axial end portion 112E of the inner tube 112, and the outer wall surface of the outer ring portion 120E can be surely brought into close contact with the inner wall surface of the through hole 130H of the fastened member 130.

As shown in fig. 1, the inner ring portion 120I of the collar member 120 is designed such that the outer diameter of the inner ring portion 120I is larger than the outer diameter of the inner cylinder 112. In this way, the structural shape of the collar member 120 is conveniently adjusted by using a limited space as much as possible, and the cross-sectional area of the magnetic path generated between the collar member 120 and the fastened member 130 can be ensured to be maximum, so that the magnetic flux density becomes high, and the amplitude of the rigidity change increases.

In the present embodiment, the vibration isolation device 1 is used for a bushing of a suspension arm (for example, the above-described subframe) of a vehicle. The vibration isolator 1 of the present invention is a structure that can be used as a suspension arm bushing and a subframe mounting bushing, and is a mounting bushing using a magnetorheological elastomer, and the rigidity of the mounting bushing can be controlled by a current applied to the magnetorheological elastomer, so that the rigidity of the suspension arm bushing and the subframe mounting bushing can be made variable to increase the rigidity when the ride quality performance (ride quality performance) is required and to decrease the rigidity when the vibration noise performance (vibration noise performance) is required, whereby both the ride quality performance and the vibration noise performance can be achieved.

As described above, by arranging the vibration isolator 1 in the bushing of the suspension arm of the vehicle, the rigidity of the bushing of the suspension arm can be made variable, and therefore the vehicle can be made compatible with both the ride quality performance and the vibration noise performance, wherein the rigidity can be improved when the ride quality performance is required, and the rigidity can be reduced when the vibration noise performance is required, and thus the vibration isolator capable of compatible with both the ride quality performance and the vibration noise performance can be provided.

In view of the above, in the vibration isolation device according to the present invention, by disposing the collar member made of a magnetic material at the axial end portion of the inner tube and in contact with the axial end portion of the inner tube, a larger current can be passed through the variable stiffness bushing assembly to increase the magnetic flux density of the magnetorheological elastomer of the variable stiffness bushing assembly, and a larger stiffness change can be obtained. Further, by grounding the collar member made of a magnetic material to the inner tube that generates the magnetic circuit, the cross-sectional area of the magnetic circuit in the coil can be increased, and the amount of the cross-sectional area increased by the magnetic circuit in the coil is the amount of the cross-sectional area increased by providing the collar member. Accordingly, the value of the applied current when the saturated magnetic flux density is reached on the cross section of the magnetic circuit in the coil becomes large. Further, the amount of the cross-sectional area of the magnetic circuit can be conveniently adjusted by the shape of the collar member, and the magnetic flux density inside the magnetorheological elastomer can be increased to obtain a larger rigidity change.

Finally, it should be noted that: the above embodiments are only for illustrating the technical solution of the present invention, and are not limiting thereof; although the invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical scheme described in the foregoing embodiments can be modified or some or all of the technical features thereof can be replaced with equivalents; such modifications and substitutions do not depart from the spirit of the corresponding technical solutions from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A vibration isolator mountable to a vehicle, the vibration isolator comprising:

a variable stiffness bushing assembly; and

a collar member made of a magnetic material;

the variable stiffness bushing assembly has:

an inner cylinder which is made of a magnetic material and has a hollow shaft portion for fastening to the vehicle;

an outer tube made of a magnetic material and disposed coaxially with the inner tube on the outer side in the radial direction of the inner tube;

a magnetorheological elastomer disposed between the inner cylinder and the outer cylinder; and

a coil for applying a magnetic field that changes the viscoelasticity of the magnetorheological elastomer,

wherein the collar member is in contact with an axial end of the inner tube of the variable stiffness bushing assembly.

2. The vibration isolator according to claim 1, further comprising:

and a fastened member made of a magnetic material, wherein the collar member is in contact with the fastened member.

3. The vibration isolator according to claim 2, wherein the fastened member has a through hole coaxial with the hollow shaft portion, and the collar member is in contact with an inner surface of the through hole.

4. A vibration isolator according to claim 3, wherein the variable stiffness bushing assembly, the collar member and the fastened member are fastened by a fastening element made of a magnetic body.

5. A vibration isolator according to claim 3, wherein the collar member is disposed in the through-hole of the fastened member in a press-fit manner.

6. The vibration isolator according to any one of claims 1 to 5, wherein an outer diameter of an inner ring portion of the collar member that contacts the inner cylinder is larger than an outer diameter of the inner cylinder.

7. The vibration isolator according to any one of claims 1 to 5, characterized in that the vibration isolator is used for a bushing of a suspension arm of a vehicle.