JP2010060023A - Vibration damping bushing - Google Patents

Abstract

[PROBLEMS] To reduce cost without impairing press-fitting retention to a cylindrical holder while maintaining a small spring constant in the twisting direction and a high spring constant in the direction perpendicular to the axis.
A first bulging portion 18 is formed at an axially central portion of an inner cylinder 12, and an outer peripheral surface of the first bulging portion is formed as a convex surface portion 20 in which both axial end portions 20B form a spherical band shape. . A second bulging portion 22 that surrounds the first bulging portion and bulges outward in the direction perpendicular to the axis is provided on the outer cylinder 14, and the second bulging portion is a straight having an outer diameter constant in the axial direction X. A cylindrical portion 24 and a spherical band portion 26 that concentrically surrounds both end portions 20B of the inner cylindrical ball band shape on both sides thereof. And the anti-vibration base | substrate 16 is each adhere | attached on the convex surface part 20 of these 1st bulging parts 18, and the internal peripheral surface of the 2nd bulging part 22, and the inner cylinder 12 and the outer cylinder 14 are connected and provided.
[Selection] Figure 2

Description

  The present invention relates to an anti-vibration bush used by being incorporated in an automobile suspension device or the like.

  2. Description of the Related Art Conventionally, in an automobile suspension device, a vibration isolating bush is used at a connection portion between a vehicle body and a suspension for the purpose of vibration damping and buffering. Such an anti-vibration bush is generally provided between a shaft member such as an inner cylinder, an outer cylinder arranged on the outer side of the shaft member, and between the shaft member and the outer cylinder so as to elastically support both. And an anti-vibration substrate made of a rubber-like elastic body.

  By the way, in the anti-vibration bush used in this type of suspension device, the spring constant in the direction perpendicular to the axis and in the axial direction is increased while the spring constant in the torsional direction and the twisting direction is increased in order to improve riding comfort and steering stability. It is required to reduce the constant.

  In order to reduce the spring constant in the twisting direction while increasing the spring constant in the direction perpendicular to the axis in response to such a requirement, a bulging portion that bulges in the axis perpendicular direction is provided at the axial center of the inner cylinder. So-called bulge type vibration-proof bushings have been developed (see Patent Documents 1 and 2 below).

Further, in Patent Document 3 below, for the purpose of further improving the bulge type vibration-proof bushing, an outer cylinder is provided with a bulging portion whose outer peripheral surface forms a convex spherical surface at the axially central portion of the inner cylinder. Is formed in a cylindrical surface having a constant outer peripheral diameter in the axial direction, and the inner peripheral surface portion of the central portion in the axial direction surrounding the convex spherical surface is formed in a concave spherical surface concentric with the convex spherical surface. Has been proposed. According to this configuration, since the outer peripheral surface of the outer cylinder is formed into a cylindrical surface while sufficiently reducing the spring constant in the twisting direction, a sufficient axial dimension for press-fitting with the cylindrical holder of the link is provided. It can be ensured and the removal force from the cylindrical holder can be improved.
Japanese Patent Laid-Open No. 09-1000085 Japanese Patent Laid-Open No. 09-100811 JP 2008-89127 A

  In the configuration described in Patent Document 3, in order to provide a concave spherical surface on the inner peripheral surface while making the outer peripheral surface of the outer cylinder a cylindrical surface, it is necessary to produce the outer cylinder by cutting, resulting in a high cost. There is.

  On the other hand, in Patent Document 1, in order to ensure the press-fitting stability into the cylindrical holder, the axially central portion of the bulging portion (expanded portion) of the outer cylinder that bulges outward in the direction perpendicular to the axis, The point which provides the large diameter part (straight cylinder part) with a constant outer diameter in an axial direction is disclosed. However, in this document, both side portions of the straight tube portion constituting the bulge portion together with the straight tube portion are formed in a simple inclined surface shape (linear shape in cross-sectional shape) inclined at a constant angle. It is difficult to effectively regulate the escape of rubber in the axial direction at the time of displacement in the direction perpendicular to the axis at both side portions inclined in a straight section like this. On the other hand, if the inclination angle (angle formed with respect to the axial direction) of the both side portions is increased in order to enhance the effect of restricting the rubber escape in the axial direction, the spring constant in the direction perpendicular to the axis increases, but in the twisting direction. At the time of displacement, not only the vibration-proof substrate is subjected to shear deformation, but also the deformation of the compression component is increased by the both sides having a large inclination angle, and the spring constant in the twisting direction is also increased. As described above, it is difficult to effectively achieve both a small spring constant in the twisting direction and a high spring constant in the direction perpendicular to the axis at both sides inclined in a straight section.

  In view of the above, the present invention can reduce costs while maintaining a small spring constant in the twisting direction and a high spring constant in the direction perpendicular to the axis, and without impairing the press-fitting retention of the link to the cylindrical holder. The object is to provide an anti-vibration bush.

  An anti-vibration bush according to the present invention includes a shaft member, an outer cylinder that concentrically surrounds the shaft member, and a vibration-proof base made of a rubber-like elastic body interposed between the shaft member and the outer cylinder. The shaft member has a first bulge portion that bulges outward in the direction perpendicular to the axis at the axial center, and the outer peripheral surface of the first bulge portion has at least both axial ends. The outer cylinder has a second bulging portion that surrounds the first bulging portion and bulges outward in the direction perpendicular to the axis, and has a second bulging portion. The projecting portion is formed in a straight cylindrical portion having a constant outer diameter in the axial direction at the central portion in the axial direction, and the both ends in the axial direction of the ball member of the shaft member are concentric on both axial sides of the straight cylindrical portion. And the anti-vibration base is formed on the convex surface portion of the first bulge portion and the inner peripheral surface of the second bulge portion. Are respectively bonded are those provided by connecting the outer cylinder and the shaft member.

  In the vibration-proof bushing having such a configuration, the first bulging portion having a spherical belt-like convex surface portion is provided at the axial central portion of the shaft member, and the second bulging surrounding the first bulging portion in the outer cylinder Since the anti-vibration base is interposed between the two, the spring constant in the twisting direction can be reduced while increasing the spring constant in the direction perpendicular to the axis. Moreover, since this outer cylinder is obtained by bending a cylindrical body having a constant plate thickness, the cost can be reduced compared to the case of cutting. On the other hand, when the outer cylinder has the second bulging part bulging outward in the direction perpendicular to the axis, it is difficult to press-fit in the cylindrical holder as it is, but the second bulging part has a straight cylindrical part. Since the axial dimension for press-fitting with the cylindrical holder can be ensured, the force to remove from the cylindrical holder (the force required to pull out) can be increased, and press-fitting retention can be improved. Can be increased. In addition, since both axial side portions of the straight tube portion are formed in a spherical band portion concentrically surrounding both axial end portions of the axial band of the shaft member, it is possible to prevent the axial direction when it is displaced in a direction perpendicular to the axial direction. The escape of the vibration base can be effectively regulated by wrapping it with the curved shape of the ball-shaped part. In addition, if the ball-shaped portion is used, it is possible to avoid the deformation of the compression component acting on the vibration-proof base as much as possible during displacement in the twisting direction, so that the spring constant in the twisting direction can be kept small. Therefore, it is effective to achieve both a small spring constant in the twisting direction and a high spring constant in the direction perpendicular to the axis.

  In the vibration-proof bushing, the convex surface portion of the first bulging portion is concentrically surrounded by the straight cylindrical portion of the second bulging portion with a cylindrical surface shape having a constant outer diameter in the axial direction. It is preferable that the center portion is configured by an axially central portion and both end portions in the axial direction of the spherical belt concentrically surrounded by the spherical belt-shaped portion of the second bulging portion. In this way, by forming the central portion in the axial direction of the first bulging portion on the inner cylinder side corresponding to the straight cylindrical portion of the second bulging portion into a cylindrical surface shape, The wall thickness is constant, and durability against displacement in the direction perpendicular to the axis can be improved.

  In the anti-vibration bush, the straight cylindrical portion of the second bulge portion is set to have an axial dimension larger than the axial center portion of the cylindrical surface shape of the first bulge portion, The anti-vibration base interposed between the convex surface portion of the first bulge portion and the inner peripheral surface of the second bulge portion may be formed with a constant thickness in the axial direction. Thus, by increasing the axial dimension of the straight tube portion on the outer tube side, it is possible to further increase the pulling force from the cylindrical holder. Also, if the axial dimensions of the straight cylinder part on the outer cylinder side and the axial center part of the cylindrical surface on the inner cylinder side are set to be the same, the thickness of the vibration isolating base at that part will be Although it becomes thicker than the thickness of the vibration-isolating base at the belt-like part, the spring constant in the direction perpendicular to the axis becomes small, but by setting the axial dimension of the straight cylinder part on the outer cylinder side to be large, By making the wall thickness in the axial direction constant, it is possible to effectively achieve both a small spring constant in the twisting direction and a high spring constant in the direction perpendicular to the axis.

  The vibration-proof bushing of the present invention can reduce the cost while maintaining the small spring constant in the twisting direction and the high spring constant in the direction perpendicular to the axis, and without impairing the press-fitting retention of the link to the cylindrical holder. Can do.

  Embodiments of the present invention will be described below with reference to the drawings.

  FIG. 1 shows an anti-vibration bush 10 according to one embodiment of the present invention. The anti-vibration bush 10 connects various link members such as a lower link and a toe control link to a suspension member in a multi-link suspension device.

  The vibration isolating bush 10 includes an inner cylinder 12 as a shaft member, an outer cylinder 14 that surrounds the inner cylinder 12 in an axially parallel and coaxial manner, and a rubber vibration isolator that is interposed between the inner cylinder 12 and the outer cylinder 14. And a base 16. As shown in FIG. 3, the inner cylinder 12 is clamped with a fastening member (not shown) such as a bolt in a state in which both end surfaces are sandwiched between brackets 1 of suspension members which are one connection part. Further, the outer cylinder 14 is fixed by being press-fitted into the cylindrical holder 3 of the link member 2 which is the other connecting portion, whereby the anti-vibration bush 10 is attached to the bracket of the link member 2 and the suspension member. 1 is connected in a vibration-proof manner.

  The inner cylinder 12 is a metal cylindrical member, and includes a first bulging portion 18 that bulges in a curved shape over the entire circumference toward the outer side Yo in the direction perpendicular to the axis at the central portion in the axial direction X. The outer peripheral surface of the first bulging portion 18 is formed as a convex surface portion 20 in which at least both axial end portions have a spherical band shape.

  In this example, the convex surface portion 20 is composed of an axial center portion 20A having a cylindrical surface shape whose outer diameter is constant in the axial direction X, and axial end portions 20B and 20B having a spherical belt shape on both sides thereof. . That is, the convex surface portion 20 is based on a spherical zone composed of a spherical surface 21 having a center P on the axis L of the inner cylinder 12, and the top of the spherical zone is cut out in parallel with the axial direction X. Between the axial end portions 20B and 20B forming a belt shape, a cylindrical surface-shaped axial central portion 20A is formed.

  Note that the axial end portions 20B and 20B of the convex surface portion 20 having a spherical belt shape are continuously continuous from the outer peripheral surface 12A of the general cylindrical portion (straight cylindrical portion having a constant outer diameter) at both axial end portions of the inner cylinder 12. Is formed.

  The outer cylinder 14 is a metal cylindrical member, and includes a second bulging portion 22 that surrounds the first bulging portion 18 and bulges in a curved shape over the entire circumference toward the outer side perpendicular to the axis. The outer cylinder 14 is formed of a cylindrical body having a constant thickness, and the second bulging portion 22 is formed by bending the axial central portion outwardly in a curved shape. In this example, the first bulging portion 18 is formed. Only the second bulging portion 22 that surrounds the outer cylinder 14 is configured.

  The second bulging portion 22 is formed in a straight cylindrical portion 24 whose outer diameter is constant in the axial direction X at the central portion in the axial direction X, and has a spherical band shape on both sides in the axial direction X of the straight cylindrical portion 24. A portion 26 is formed, and the second bulging portion 22 is constituted by the straight tube portion 24 and the ball-like portions 26 and 26 on both sides thereof. More specifically, the second bulging portion 22 is basically based on a spherical band formed of a spherical surface 23 having the same center P as the convex surface portion 20 of the first bulging portion 18, and the top of the spherical band is defined in the axial direction X. By forming the straight cylindrical portion 24 parallel to the straight cylindrical portion 24, the straight cylindrical portion 24 is formed between the ball-shaped portions 26, 26 at both axial end portions. It should be noted that the spherical band portion 26 is not a strict spherical band in a state before the drawing of the outer cylinder 14, but is located at a position where the center P is shifted in the direction perpendicular to the axis Y from the axis L of the outer cylinder 14, By performing a drawing process in the direction of diameter reduction after the vulcanization molding of the vibration-proof substrate 16, a center P is formed in a spherical shape located on the axis L as shown in FIG.

  In the second bulging portion 22 configured as described above, the straight tube portion 24 concentrically surrounds the cylindrical central axial portion 20A of the first bulging portion 18, and is a cross section shown in FIG. In the shape, both 24 and 20A are provided in parallel to each other and in parallel to the axis L. In addition, the ball-shaped portion 26 concentrically surrounds the ball-shaped axial end portion 20 </ b> B of the first bulging portion 18. Further, the axial dimension M of the straight tube portion 24 is set to be larger than the axial dimension N of the columnar axial central portion 20A of the first bulging portion 18 (M> N).

  The anti-vibration base body 16 is vulcanized and bonded to the convex surface portion 20 of the first bulging portion 18 and the concave surface portion 22A formed by the inner peripheral surface of the second bulging portion 22, respectively. It is a cylindrical rubber member that connects the cylinder 14. By configuring the first bulging portion 18 of the inner cylinder 12 and the second bulging portion 22 of the outer cylinder 14 as described above, the convex surface portion 20 of the first bulging portion 18 and the concave surface of the second bulging portion 22. The anti-vibration base 16 interposed between the portions 22A is formed with a constant thickness in the axial direction X. Specifically, the thickness T1 of the vibration isolation base 16 is constant in the axial direction X between the axial center portion 20A of the convex surface portion 20 and the straight cylindrical portion 24 of the second bulging portion 22, and the convex surface portion 20 The thickness T2 of the vibration isolating base 16 is constant in the axial direction X between the axial end portions 20B and the ball-shaped portion 26 of the second bulging portion 22, and the thicknesses T1 and T2 are set to be substantially the same. ing. Note that the thickness T2 of the anti-vibration base 16 in the ball-shaped portion 26 is a radial thickness extending from the center P of the ball band.

  On both end surfaces in the axial direction of the vibration isolation base 16, annular straight portions 28 that are recessed in a cross-sectional curved shape toward the axially inward Xi side are provided over the entire circumference. As shown in FIG. 2, the straight portion 28 extends to the axially inward Xi rather than the axial outer end 26 </ b> A of the ball-shaped portion 26 of the outer cylinder 14, and accordingly, the bottom of the straight portion 28 (that is, the straight portion). 28 </ b> A) 28 </ b> A is located in the axially inward Xi with respect to the outer end 26 </ b> A of the ball-shaped portion 26. Further, in the cross-sectional shape shown in FIG. 2, the convex portion is formed such that an extension line 30 (straight line extending in the axial direction X) 30 of the axial center portion 20 </ b> A of the convex portion 20 intersects the arc 32 that forms the bottom portion of the straight portion 28. The relationship between 20 and the straight portion 28 is set.

  The anti-vibration base 16 has a rubber layer 16A extending on the axially outward Xo side so as to cover the outer peripheral surface 12A of the inner cylinder 12 on the axially outward Xo side of the first bulging portion 18 in a thin film shape. It is comprised.

  When manufacturing the vibration isolating bushing 10, the inner cylinder 12 having the first bulging portion 18 and the outer cylinder 14 having the second bulging portion 20 are arranged in a molding die (not shown), and the molding is performed. By injecting a rubber material into the mold, the vibration-proof base 16 is vulcanized between the inner cylinder 12 and the outer cylinder 14. The obtained vulcanized molded body is then subjected to a drawing process on the outer cylinder 14 to reduce the diameter of the outer cylinder 14, whereby the vibration isolating bush 10 shown in FIG. 1 is obtained.

  In the vibration isolating bushing 10, the first bulging portion 18 is provided in the inner cylinder 12, and the second bulging portion 22 surrounding the first bulging portion 18 is provided in the outer cylinder 14, so Since the vibration base 16 is interposed, the spring constant in the twisting direction Z (see FIG. 3) can be reduced while increasing the spring constant in the direction perpendicular to the axis Y. In particular, since the convex surface portion 20 of the first bulging portion 18 and the concave surface portion 22A of the second bulging portion 22 are both constituted by concentric convex surfaces and concave surfaces based on a spherical belt shape, displacement in the twisting direction Z At this time, the deformation of the anti-vibration base 16 interposed between the first bulging portion 18 and the second bulging portion 22 can be mainly shear deformation, and the spring constant in the twisting direction Z is effectively reduced. can do.

  Moreover, since the outer cylinder 14 is obtained by bending a cylindrical body having a constant plate thickness, the cost can be reduced as compared with the above conventional one in which the outer cylinder is formed by cutting.

  On the other hand, when the outer cylinder 14 has a bulging portion, as it is, it is difficult to press fit and hold in the cylindrical cylindrical holder 3 in which the diameter of the inner peripheral surface is constant in the axial direction X. By providing the straight cylindrical portion 24 in the second bulging portion 22, it is possible to ensure an axial dimension for press-fitting with the cylindrical holder 3. Therefore, it is possible to enhance the press-fitting retention by increasing the pulling force (force required for pulling out) from the cylindrical holder 3.

  Further, in the case of the second bulging portion 22, both sides in the axial direction of the straight tube portion 24 are formed in the ball-shaped portions 26 and 26 that concentrically surround both the ball-shaped axial end portions 20 </ b> B and 20 </ b> B of the inner tube 12. As a result, the escape of the anti-vibration base 16 toward the axially outward Xo during displacement in the direction perpendicular to the axis Y can be effectively regulated by wrapping it with the curved shape of the ball-shaped portion 26. . Therefore, the spring constant in the direction perpendicular to the axis Y can be effectively increased.

  Unlike the above-described straight inclined surface portion as in the conventional case, if both sides of the straight cylindrical portion 24 are a ball-shaped portion 26 as in the present embodiment, when the displacement in the twisting direction Z occurs, Since the deformation can be avoided as much as possible, the spring constant in the twisting direction Z can be kept small. Therefore, it is effective to achieve both a small spring constant in the twisting direction Z and a high spring constant in the direction perpendicular to the axis Y.

  In addition, the axial dimension M of the straight cylinder part 24 on the outer cylinder 14 side is set to be larger than the axial dimension N of the axial center part 20A of the cylindrical surface on the inner cylinder 12 side. It is possible to further increase the detachment force from the. In addition, by setting the dimensions, as described above, the thickness of the anti-vibration base 16 in the axial direction X can be made constant, and both a small spring constant in the twisting direction Z and a high spring constant in the direction perpendicular to the axis Y can be achieved. Is advantageous. Further, since the thickness of the vibration isolating substrate 16 is constant, it is possible to suppress the application of non-uniform stress when displaced in the direction perpendicular to the axis Y, and to improve the vibration isolating performance and durability.

  Further, since the straight portion 28 is formed as described above, the spring constant in the twisting direction Z can be set effectively low.

  In the above-described embodiment, the cylindrical surface-shaped axial central portion 20A is provided on the convex surface portion 20 of the first bulging portion 18 on the inner cylinder 12 side, but the convex surface portion 20 is not provided with such a cylindrical surface portion. May be formed in the shape of a sphere. By making the entire convex surface portion 20 into a spherical belt shape, the spring constant in the direction perpendicular to the axis Y can be further increased while keeping the spring constant in the twisting direction Z small. However, in that case, when the displacement is made in the direction perpendicular to the axis Y, local pressure acts at the central portion in the axial direction where the thickness of the antivibration base 16 is reduced, which impairs durability. Therefore, in terms of durability, as in the above-described embodiment, a cylindrical surface portion is provided in the axial center portion 20A of the first bulging portion 18 on the inner cylinder 12 side so as to correspond to the straight tubular portion 24 of the second bulging portion 22. Is preferably provided.

  In the above embodiment, the first bulging portion 18 of the inner cylinder 12 is integrally formed of a metal material in order to obtain a bulge type bush. However, a resin-made annular covering is provided on the outer peripheral surface of the inner cylinder. For example, the bulging portion may be formed. Although not enumerated one by one, various modifications can be made without departing from the spirit of the present invention.

  INDUSTRIAL APPLICABILITY The present invention can be used for various types of anti-vibration bushes such as an anti-vibration bush used in an automobile suspension device and a cylindrical anti-vibration bush as an engine mount.

Sectional view of vibration-proof bushing according to the embodiment An enlarged sectional view of the main part of the anti-vibration bush Sectional view showing the assembled state of the anti-vibration bush

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Anti-vibration bush 12 ... Inner cylinder (shaft member), 12A ... Outer peripheral surface 14 ... Outer cylinder 16 ... Anti-vibration base | substrate 18 ... 1st bulging part 20 ... Convex part, 20A ... Axial center part, 20B ... Axial direction End portion 22 ... second bulge portion 24 ... straight cylindrical portion 26 ... spherical belt portion M ... axial dimension N of the straight cylindrical portion ... axial dimension X in the axial center of the first bulge portion ... axial direction Y ... Axis perpendicular direction, Yo ... Axis perpendicular direction outward

Claims (3)

In an anti-vibration bush comprising: a shaft member; an outer cylinder that concentrically surrounds the shaft member; and a vibration-proof base made of a rubber-like elastic body interposed between the shaft member and the outer cylinder.
The shaft member has a first bulge portion that bulges outward in a direction perpendicular to the axis at a central portion in the axial direction, and the outer peripheral surface of the first bulge portion has at least both axial end portions formed in a spherical band shape. Formed on the convex surface,
The outer cylinder has a second bulging portion that surrounds the first bulging portion and bulges outward in the direction perpendicular to the axis, and the second bulging portion has an outer diameter at a central portion in the axial direction. It is formed into a straight tube portion that is constant in the axial direction, and is provided with a ball-shaped portion that concentrically surrounds both axial ends of the shaft member in the axial direction on both sides in the axial direction of the straight tube portion,
The anti-vibration base is provided by connecting the shaft member and the outer cylinder by being bonded to the convex surface portion of the first bulge portion and the inner peripheral surface of the second bulge portion, respectively.
Anti-vibration bush characterized by that.   The convex surface portion of the first bulging portion has an axial central portion that is concentrically surrounded by the straight cylindrical portion of the second bulging portion, with an outer diameter forming a constant cylindrical surface shape in the axial direction, The anti-vibration bushing according to claim 1, wherein the anti-vibration bushing is configured by a spherical belt-shaped axially opposite end portions surrounded concentrically by the spherical belt-shaped portion of the second bulge portion.   The straight cylindrical portion of the second bulging portion is set to have a larger axial dimension than the columnar axial central portion of the first bulging portion, and the convex surface of the first bulging portion. The anti-vibration bush according to claim 2, wherein the anti-vibration base interposed between the portion and the inner peripheral surface of the second bulging portion is formed with a constant thickness in the axial direction.

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