The present invention relates to a suspension bushing attached between a vehicle body and a suspension arm, and to a suspension device of torsion-beam type that uses this suspension bushing.
Japanese Laid-Open Patent Publication No. 2010-054017 discloses an antivibration apparatus (antivibration bushing) used as a suspension bushing of an automobile. This antivibration bushing includes a space filled with rubber between an inner cylinder and an outer cylinder, and a protrusion on the outer circumference of the inner cylinder. When an external force in a direction orthogonal to the axis is applied to the antivibration bushing, the inner cylinder moves in the axis-orthogonal direction and the protrusion contacts the outer cylinder. In this way, the rigidity against the external force in the axis-orthogonal direction is increased.
It is important to reduce the misalignment between the center of the outer cylinder and the center of the inner cylinder, in order to improve the vehicle maneuvering stability. However, the rubber between the inner cylinder and the outer cylinder deforms when the suspension bushing receives an external force. If this deformation of the rubber is significant, the vehicle maneuvering stability is reduced.
By reducing the volume of the rubber or by using rubber with a high level of hardness, it is possible to increase the rigidity of the rubber and reduce the misalignment between the center of the inner cylinder and the center of the outer cylinder. However, when the rigidity of the rubber is increased, there is a possibility that the vibration characteristics are worsened and the ride quality is adversely affected.
The present invention has been devised in order to solve this type of problem, and has the object of providing a suspension bushing and a suspension device that are capable of improving the maneuvering stability without adversely affecting the ride quality.
A first aspect of the present invention is:
a suspension bushing comprising an inner cylinder and an outer cylinder that are arranged on a same axial line, and an elastic member interposed between the inner cylinder and the outer cylinder, wherein
a convex portion is formed on an outer circumference of the inner cylinder,
a slit is formed in an inner circumference of the outer cylinder,
the convex portion is arranged inside the slit, and has a tapered shape in which a width in a direction parallel to the axial line decreases moving away from the axial line, and
the slit has a shape in which a space in the direction parallel to the axial line decreases moving away from the axial line.
A second aspect of the present invention is:
a suspension device of torsion-beam type that supports a right-left pair of trailing arms in a manner to be swingable relative to a vehicle body, by using a suspension bushing, wherein
the suspension bushing comprises:
an inner cylinder attached to the vehicle body;
an outer cylinder arranged on a same axial line as the inner cylinder and attached to the trailing arm; and
an elastic member interposed between the inner cylinder and the outer cylinder,
a convex portion is formed on an outer circumference of the inner cylinder,
a slit is formed in an inner circumference of the outer cylinder,
the convex portion is arranged inside the slit, and has a shape in which a length in a direction parallel to the axial line decreases moving away from the axial line, and
the slit has a shape in which a space in the direction parallel to the axial line decreases moving away from the axial line.
According to the present invention it is possible to improve the maneuvering stability without adversely affecting the ride quality.
Preferred embodiments of a suspension bushing and a suspension device according to the present invention will be presented and described below with reference to the accompanying drawings.
A suspension device 10 according to the present embodiment will be described using
The suspension device 10 is a torsion-beam type, and includes a right-left pair of trailing arms 14R and 14L, a torsion beam 16 that connects the trailing arms 14R and 14L in the pair to each other, and a pair of spring receivers 18R and 18L that support the bottom ends of coil springs (not shown in the drawings).
Cylindrical portions 20R and 20L are formed on the forward-direction VF tips of the trailing arms 14R and 14L. The pair of cylindrical portions 20R and 20L are also referred to collectively below as cylindrical portions 20. An axial line A′ of the cylindrical portion 20R extends in a manner to progress in the backward direction VB of the vehicle body 12 as it progresses in the rightward direction VR of the vehicle body 12. An axial line A′ of the cylindrical portion 20L extends in a manner to progress in the backward direction VB of the vehicle body 12 as it progresses in the leftward direction VL of the vehicle body 12.
Suspension bushings 28R and 28L are press-fitted into the cylindrical portions 20R and 20L. The pair of suspension bushings 28R and 28L are also referred to collectively below as suspension bushings 28. Outer cylinders 30 (see
In a state where the suspension bushing 28R has been press-fitted into the cylindrical portion 20R, an axial line A of the suspension bushing 28R extends from the inside to the outside in the vehicle width direction, that is, in a manner to progress in the backward direction VB of the vehicle body 12 as it progresses in the rightward direction VR of the vehicle body 12. The inclination angle of the axial line A of the suspension bushing 28R relative to the vehicle width direction (VR, VL) is approximately +27° to +33°, preferably approximately +30°, with the clockwise direction seen from the upward direction VU being the +direction. Similarly, in a state where the suspension bushing 28L has been press-fitted into the cylindrical portion 20L, an axial line A of the suspension bushing 28L extends from the inside to the outside in the vehicle width direction, that is, in a manner to progress in the backward direction VB of the vehicle body 12 as it progresses in the leftward direction VL of the vehicle body 12. The inclination angle of the axial line A of the suspension bushing 28L relative to the vehicle width direction (VR, VL) is approximately −27° to −33°, preferably approximately −30°, with the clockwise direction seen from the upward direction VU being the +direction. The inclination angles of the axial lines A of the suspension bushings 28R and 28L are not limited to those of the embodiment described above. For example, the inclination angles may be 0°.
The directions used in the following description are defined as shown below. The X direction is a direction parallel to the axial line A of the suspension bushing 28. Along this X direction, one direction is the +X direction and the other direction is the −X direction. For example, as shown in
The outer cylinder 30 is formed by semi-cylindrical divided members 32 and 32 divided into two by a plane that is parallel to the axial line A and passes through the axial line A. The outer cylinder 30 may instead be divided into three or more pieces. The outer cylinder 30 is preferably divided uniformly, with the axial line A as the center. For example, in a case where the outer cylinder 30 is divided into three pieces, the outer cylinder 30 is preferably divided at intervals of 120° centered on the axial line A, and in a case where the outer cylinder 30 is divided into four pieces, the outer cylinder 30 is preferably divided at intervals of 90° centered on the axial line A.
When the suspension bushing 28 is in the finished product state, gaps G (
The following describes the divided member 32 forming the outer cylinder 30, using
A slit 38 is formed in the guide 36. The slit 38 is formed such that a center line CL1 of the slit 38 in the longitudinal direction is arranged along the Z direction.
The slit 38 is formed by a pair of guide wall surfaces 40 and 40 positioned on the +X-direction and −X-direction sides. As shown in
In other words, the slit 38 has a tapered shape in which the space W1 in the X direction decreases in both the +X direction and the −X direction moving away from the axial line A. As shown in
A hole 42, which penetrates through the outer circumferential surface side of the divided members 32 and extends in the Z direction, is formed in the floor portion of the slit 38.
The inner cylinder 50 will be described using
The convex portions 54 are formed such that a center line CL2 of each convex portion 54 in the longitudinal direction is arranged along the Z direction, in the same manner as the slit 38 of the outer cylinder 30.
Each convex portion 54 includes a pair of convex portion wall surfaces 56 and 56 positioned on the +X-direction side and the −X-direction side. As shown in
In other words, the convex portion 54 has a tapered shape in which the width W2 in the X direction decreases in both the +X direction and the −X direction moving away from the axial line A. As shown in
As shown in
As shown in
The operation of the suspension bushing 28 will be described using
As shown in
As shown in
The suspension bushing 28 operates to decrease the misalignment in the Y direction. This principle is thought of in the following manner. As described above, the guide wall surfaces 40 and the convex portion wall surfaces 56 have tapered shapes. Therefore, the X-direction component FLx acting on the guide wall surface 40 can be thought of as being broken down into a component FLx1 in a direction parallel to the guide wall surface 40 and a component FLx2 in a direction orthogonal to the guide wall surface 40. For example, in the suspension bushing 28L shown in
If the center Co of the outer cylinder 30 is on the axial line A, the component FLx is uniform across the Z direction. On the other hand, if the center Co of the outer cylinder 30 is offset in the +Y direction from the axial line A, the component FLx1 generated at the guide wall surface 40 on the side in a direction opposite the direction of the offset becomes large, and a force returning this offset to the original state acts on the outer cylinder 30. In other words, the component FLx1 acts to hold the center Co of the outer cylinder 30 on the axial line A.
Various modifications can be envisioned for the suspension bushings 28 and the suspension device 10 according to the embodiment described above.
As shown in
In the suspension bushing 28 shown in
Each convex portion 54 has a shape in which the decrease rate of the width W2 increases moving away from the axial line A. In the case of this modification, in the cross section that passes through the convex portions 54 and the axial line A and is parallel to the axial line A, the curvatures of the convex portion wall surfaces 56 may be constant (that is, an arc) regardless of the distance from the axial line A, or the curvatures of the convex portion wall surfaces 56 may increase or decrease moving away from the axial line A. The curvatures of the convex portion wall surfaces 56 and the curvatures of the guide wall surfaces 40 may be the same, or may be different.
If the inner cylinder 50 rotates in the Z direction relative to the outer cylinder 30 or the outer cylinder 30 rotates in the Z direction relative to the inner cylinder 50, the distortion amount of the elastic member 70 becomes greater farther from the axial line A. Therefore, it is preferable to increase the compression amount of the elastic member 70 that is far from the axial line A. According to the suspension bushing 28 shown in
In the suspension bushing 28 shown in
Each convex portion 54 has a shape in which the decrease rate of the width W2 decreases moving away from the axial line A. In the case of this modification, in the cross section that passes through the convex portions 54 and the axial line A and is parallel to the axial line A, the curvatures of the convex portion wall surfaces 56 may be constant (that is, an arc) regardless of the distance from the axial line A, or the curvatures of the convex portion wall surfaces 56 may increase or decrease moving away from the axial line A. The curvatures of the convex portion wall surfaces 56 and the curvatures of the guide wall surfaces 40 are the same.
A suspension bushing 28 includes an inner cylinder 50 and an outer cylinder 30 that are arranged on the same axial line A, and an elastic member 70 interposed between the inner cylinder 50 and the outer cylinder 30. A convex portion 54 is formed on the outer circumference of the inner cylinder 50, and a slit 38 is formed in the inner circumference of the outer cylinder 30. The convex portion 54 is arranged within the slit 38, and has a tapered shape in which the width W2 in a direction parallel to the axial line A decreases moving away from the axial line A. The slit 38 has a shape in which the space W1 in the direction parallel to the axial line A decreases moving away from the axial line A.
According to the above configuration, the convex portion 54 and the slit 38 have tapered shapes, due to which a component FLx1 of a component FLx, which is in an axial line direction (X direction) and acts on the outer cylinder 30, acts to hold the center Co of the outer cylinder 30 on the axial line A. Therefore, it is possible to reduce the misalignment between the center Co of the outer cylinder 30 and the center Ci of the inner cylinder 50, and it is possible to improve the maneuvering stability of the vehicle. Furthermore, there is no need to reduce the volume of the elastic member 70 and no need to use the elastic member 70 with a high degree of hardness, and therefore there is no adverse effect on the ride quality.
As shown in
According to the above configuration, it is possible to increase the surface area of the convex portion wall surfaces 56 and the surface area of the guide wall surfaces 40, and to distribute the force applied to the elastic member 70 when the elastic member 70 is compressed by the convex portion wall surfaces 56 and the guide wall surfaces 40. Therefore, wear on the elastic member 70 can be suppressed.
As shown in
According to the above configuration, it is possible to realize more compression of the elastic member 70 arranged outward in the radial direction (+Y direction) using the convex portion wall surfaces 56 and the guide wall surfaces 40. As a result, wear on the elastic member 70 can be suppressed.
As shown in
According to the above configuration, it is possible to improve the maneuvering stability without adversely affecting the ride quality.
As shown in
According to the above configuration, it is possible to improve the maneuvering stability without adversely affecting the ride quality.
The suspension device 10 of torsion-beam type supports the right-left pair of trailing arms 14R and 14L in a manner to be swingable relative to the vehicle body 12, by using the suspension bushings 28R and 28L.
According to the above configuration, it is possible to improve the maneuvering stability without adversely affecting the ride quality.
The suspension bushing and the suspension device according to the present invention are not limited to the above-described embodiments, and it goes without saying that various configurations could be adopted therein without departing from the essence and gist of the present invention.
Number | Date | Country | Kind |
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2018-136343 | Jul 2018 | JP | national |
Filing Document | Filing Date | Country | Kind |
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PCT/JP2019/024860 | 6/24/2019 | WO | 00 |