JP7758563B2 - Suspension bushings - Google Patents

Description

The present invention has a structure in which an inner shaft member and an outer cylindrical member, which are arranged radially spaced apart, are connected by a rubber elastic body, and can be suitably used as a suspension bushing for automobiles.

Patent Document 1 discloses a rubber bushing, a type of vibration-damping device interposed between components that make up a vibration transmission system, which has a structure in which an inner shaft member and an outer cylindrical member positioned outside the inner shaft member at a distance from each other are connected by a rubber elastic body interposed between them.

Furthermore, in order to adjust the spring characteristics of such rubber bushings, for example to vary the spring characteristics in different radial directions or to adjust the spring characteristics in the prying direction, many of these rubber bushings have recesses that penetrate the rubber elastic body in the axial direction. Furthermore, such recesses are generally formed over a predetermined length in the circumferential direction of the rubber elastic body.

However, in conventional rubber bushings with such recesses, there were restrictions on the ratio of the spring constant in the recess direction to the spring constant in the solid direction. At the same time, durability also had to be met.

Patent No. 3680575

The present invention was made against the backdrop of the circumstances described above, and its objective is to provide a suspension bushing with a novel structure that allows for highly accurate tuning of the ratio of the spring constant in the outboard direction to the spring constant in the solid direction, without reducing durability.

A first aspect of the present invention is characterized by comprising an inner axial member, an outer cylindrical member arranged radially outward from the inner axial member, and a rubber elastic body connecting the inner axial member and the outer cylindrical member , wherein the rubber elastic body is arranged opposite each other across the inner axial member in a first radial direction and has a pair of hollow portions that penetrate the inner axial member in the axial direction, and a pair of non-through holes that are arranged opposite each other in a second radial direction perpendicular to the first radial direction and are a pair of holes extending from both end faces in the axial direction to a middle region in the axial direction, and are formed in an arc shape that convex outward in the second radial direction, wherein the hole diameter in the second radial direction of the pair of non-through holes is set smaller than the hole diameter in the first radial direction of the pair of hollow portions, and each of the pair of non-through holes is arranged on the outer cylindrical member side.

In a suspension bushing constructed according to this embodiment, a pair of arc-shaped non-through holes are formed that convex outward in a second radial direction perpendicular to the first radial direction. This allows the spring constant ratio between the first radial direction (outer diameter direction) and the second radial direction (solid direction) to be tuned with high precision by, for example, arbitrarily changing the shape (hole diameter and depth) of the non-through holes. Furthermore, by making the diameter of the non-through holes smaller than the diameter of the outer diameter portion, it is possible to lower the spring constant in the second radial direction (solid direction) while maintaining a low spring constant in the first radial direction (outer diameter direction), thereby satisfying the vehicle's required performance. Furthermore, by making the non-through holes arc-shaped, stress generated in the non-through holes can be reduced when a torsional input is applied, preventing a decrease in durability.

In addition, because the non-through holes can be located on the outer tubular member side, which has a larger rubber volume, the spring constant in the second radial direction (solid direction) can be efficiently lowered while maintaining the spring constant in the first radial direction (outer diameter direction). Furthermore, when an input is applied in the first radial direction (outer diameter direction) or torsional direction, because the non-through holes are located on the outer tubular member side, which has a longer circumferential length, the stress generated in the non-through holes can be reduced, preventing a decrease in durability.

A second aspect of the present invention is a suspension bushing according to the first aspect, wherein the outer peripheral shape of the inner shaft member is circular when viewed in the axial direction, and the outer peripheral circle of the inner shaft member and a first inscribed circle defined as a circle tangent to each of the inner edges of the pair of blind holes are concentric when viewed in the axial direction.

In this suspension bushing, the non-through holes can be efficiently positioned on the outer cylindrical member side, which has a larger rubber volume, making it possible to efficiently lower the spring constant in the second radial direction (solid direction) while maintaining the spring constant in the first radial direction (outer diameter direction). Furthermore, when an input is applied in the first radial direction (outer diameter direction) or torsional direction, the entire non-through hole is positioned on the outer cylindrical member side, which has a longer circumferential length, further reducing the stress generated in the non-through hole and further preventing a decrease in durability.

A third aspect of the present invention is a suspension bushing according to the second aspect, wherein the pair of hollow portions are formed in an arc shape that is convex outward in the first radial direction, and when viewed from the axial direction, the first inscribed circle and a second inscribed circle defined as a circle tangent to each of the inner edges of the pair of hollow portions are concentric circles.

In this suspension bushing, hollow portions are arranged in the first radial direction (outline direction) and blind holes are arranged in the second radial direction (solid direction), allowing for efficient use of the circumferential space of the rubber elastic body. Furthermore, when input is applied in the first radial direction (outline direction) or torsional direction, stress generated in the hollow portions as well as the blind holes can be reduced, ensuring sufficient durability of the hollow portions.

A fourth aspect of the present invention is a suspension bushing according to any one of the first to third aspects, wherein the inner axial member extends at different lengths from both axial end faces of the rubber elastic body, and the rubber elastic body has, at one axial end face, a protrusion formed in the opposing region between the inner edge of at least one of the pair of non- through holes and the inner axial member.

In the suspension bushing of this aspect, the protrusion is disposed on the inner shaft member side and the blind hole is disposed on the outer cylindrical member side, so that the radial space of the rubber elastic body can be used efficiently. Furthermore, since the protrusion acts as an identification protrusion when assembling the bushing to a vehicle,
Even if the lengths of the inner shaft member are different on both sides in the axial direction, incorrect assembly can be advantageously prevented.

A fifth aspect of the present invention is a suspension bushing according to the fourth aspect, wherein the protrusion is formed at a position away from a dividing line that divides the inner shaft member in two in the second radial direction to one side in the first radial direction.

In this suspension bushing, the protrusion is located away from the parting line of the inner shaft member to one side in the first radial direction, thereby reducing the impact of the protrusion on durability.

In a suspension bushing constructed in accordance with the present invention, a pair of arc-shaped non-through holes are formed that convex outward in a second radial direction perpendicular to the first radial direction. This allows the spring constant ratio between the first radial direction (outer diameter direction) and the second radial direction (solid direction) to be tuned with high precision by, for example, arbitrarily changing the shape (hole diameter and depth) of the non-through holes. Furthermore, by making the diameter of the non-through holes smaller than the diameter of the outer diameter portion, it is possible to lower the spring constant in the second radial direction (solid direction) while maintaining a low spring constant in the first radial direction (outer diameter direction), thereby satisfying the vehicle's required performance. Furthermore, by making the non-through holes arc-shaped, stress generated in the non-through holes can be reduced when torsional input is applied, preventing a decrease in durability.

In addition, because the non-through holes can be located on the outer tubular member side, which has a larger rubber volume, the spring constant in the second radial direction (solid direction) can be efficiently lowered while maintaining the spring constant in the first radial direction (outer diameter direction). Furthermore, when an input is applied in the first radial direction (outer diameter direction) or torsional direction, because the non-through holes are located on the outer tubular member side, which has a longer circumferential length, the stress generated in the non-through holes can be reduced, preventing a decrease in durability.

1 is a plan view showing a suspension bushing according to an embodiment of the present invention; 2 is a cross-sectional view of the suspension bush taken along line II of FIG. 1. FIG. 2 is a perspective view of FIG. 1 showing a suspension bushing.

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

First, Figures 1 to 3 show an automotive suspension bushing 10 as one embodiment of the present invention. This bushing 10 has an inner tubular metal fitting 12 as an inner shaft member and an outer tubular metal fitting 14 as an outer tubular member, which are elastically connected by a rubber elastic body 16, and has a generally cylindrical shape overall. The inner tubular metal fitting 12 of this bushing 10 is attached to the body frame of the automobile, while the outer tubular metal fitting 14 is attached to the suspension arm, so that it is attached to the mounting location of the suspension arm relative to the body frame and elastically connects the suspension arm to the body frame.

More specifically, the inner cylindrical member 12 is formed from a rigid material such as a metal material like steel, and has a thick, straight, cylindrical shape.

The outer cylindrical member 14 is disposed on the outer peripheral surface of the inner cylindrical member 12, spaced apart radially outward. Like the inner cylindrical member 12, the outer cylindrical member 14 is formed from a rigid material such as steel and has a straight, cylindrical shape. The inner cylindrical member 12 and outer cylindrical member 14 are disposed approximately coaxially with each other. The outer cylindrical member 14 is thinner and has a shorter axial length than the inner cylindrical member 12. The outer peripheral surfaces of the corners at the open ends on both axial sides of the outer cylindrical member 14 are tapered, with the diameter decreasing axially outward.

The outer cylindrical fitting 14 is fitted onto the inner cylindrical fitting 12, and they are positioned on the same central axis. The outer cylindrical fitting 14 is disposed at the axial center of the inner cylindrical fitting 12 so as to cover the outer peripheral surface of the axially middle portion of the inner cylindrical fitting 12. As a result, a circular ring region extending continuously in the circumferential direction and of a substantially constant size is formed between the radially opposing surfaces of the inner cylindrical fitting 12 and the outer cylindrical fitting 14. In particular, in this embodiment, the inner diameter of the outer cylindrical fitting 14 is set to approximately twice the outer diameter of the inner cylindrical fitting 12, so that this circular ring region is formed with a sufficient width in the radial direction.

A rubber elastic body 16 is interposed in the annular region formed between the radially opposing surfaces of the inner tubular member 12 and the outer tubular member 14, elastically connecting the inner tubular member 12 and the outer tubular member 14 via the rubber elastic body 16. The rubber elastic body 16 has a generally thick-walled cylindrical shape, with its inner circumferential surface bonded to the outer circumferential surface of the inner tubular member 12 and its outer circumferential surface bonded to the inner circumferential surface of the outer tubular member 14. This rubber elastic body 16 can be advantageously formed as an integrally vulcanization-molded product in which the rubber elastic body 16 is vulcanization-bonded to the inner tubular member 12 and the outer tubular member 14 by setting the inner tubular member 12 and the outer tubular member 14, which have been subjected to adhesive treatment as necessary, in a vulcanization-molding mold for the rubber elastic body 16, filling the gap between the inner tubular member 12 and the outer tubular member 14 with rubber material, and then vulcanizing the rubber elastic body 16.

Furthermore, if necessary, the outer tubular member 14 of the integrally vulcanized molded product obtained in this manner may be subjected to diameter reduction processing such as eight-way drawing. This results in the desired bushing 10, as shown in Figures 1 to 3.

The axial dimension of the rubber elastic body 16 of the bushing gradually decreases from the inner circumferential side to the outer circumferential side, and its inner circumferential surface is bonded to the outer circumferential surface of the inner tubular fitting 12, while its outer circumferential surface is bonded to almost the entire inner circumferential surface of the outer tubular fitting 14. In other words, both axial end faces 22, 22 of the rubber elastic body 16 have approximately tapered cylindrical surfaces that protrude axially outward from the outer tubular fitting 14 toward the inner tubular fitting 12. Furthermore, the points at which the axial dimension of the rubber elastic body 16 is smallest are located near the outer tubular fitting 14.

The rubber elastic body 16 is also formed with a pair of hollow portions 24, 24 that extend axially through it. Each hollow portion 24 extends circumferentially through the approximate radial center of the rubber elastic body 16 for approximately one-quarter of the circumference, and is positioned opposite each other in the first radial direction (the up-and-down direction in FIG. 1 ), sandwiching the inner tubular fitting 12. In particular, in this embodiment, the hollow portions 24 at both circumferential ends have a radial width dimension that spans approximately the entire radial thickness of the rubber elastic body 16. The circumferential center of the hollow portion 24 is also formed with an inner circumferential stopper rubber 26 that is bonded to the inner tubular fitting 12 and protrudes radially outward from the inner tubular fitting 12 side, and an outer circumferential stopper rubber 28 that is bonded to the outer tubular fitting 14 and protrudes radially inward from the outer tubular fitting 14 side. The protruding tip surfaces of the inner stopper rubber 26 and the outer stopper rubber 28 are positioned opposite each other at a predetermined radial distance, sandwiching the hollow portion 24.

These stopper rubbers 26, 28 protrude into the hollow portions 24, giving the hollow portions 24 a generally H-shaped cross-section as shown in FIG. 1. In other words, the radial width (hole diameter) of each hollow portion 24 varies circumferentially, being smaller in the circumferential center and larger at both circumferential ends. Furthermore, because both circumferential ends of the hollow portions 24 have a radial width (hole diameter) that spans substantially the entire area between the radially opposing surfaces of the inner tubular member 12 and the outer tubular member 14, the rubber elastic body 16 is essentially divided circumferentially by the pair of hollow portions 24, 24. The inner tubular member 12 and the outer tubular member 14 are interconnected only in the areas where the pair of hollow portions 24, 24 is not formed, i.e., the pair of elastic connecting portions 34, 34 that face each other in the second radial direction perpendicular to the opposing direction of the hollow portions 24, 24. Furthermore, the stopper rubbers 26, 28 are connected and integrated with adjacent elastic connecting portions 34, 34 at both circumferential ends of the hollow portion 24 via rubber winding portions 30, 30 formed with slight thickness on the surfaces of the inner tubular member 12 and outer tubular member 14.

The protruding tip surface of the outer circumferential stopper rubber 28 is an inclined surface that becomes lower from the axial center toward both axial sides, and as a whole, in an axial cross section as shown in Figure 2, it has a roughly mountain-shaped cross section with the protruding height being greatest at the axial center. On the other hand, the protruding height of the inner circumferential stopper rubber 26 is roughly constant throughout.

Furthermore, each of the elastic connecting portions 34, 34 formed by the rubber elastic body 16 has a length of approximately one-quarter of the circumference in the circumferential direction, and both circumferential side portions of each elastic connecting portion 34 are configured as variable thickness portions over a predetermined circumferential length, with the axial thickness gradually decreasing as the portion approaches the hollow portion 24. In other words, both axial end surfaces of the elastic connecting portion 34 in the circumferential direction are inclined surfaces 36, 36 that gradually slope axially inward toward the hollow portion 24.

The rubber elastic body 16 is also formed with a pair of non-through holes 38, 38, 38, 38, arranged opposite each other in a second radial direction (solid direction) perpendicular to the first radial direction (outer diameter direction). The non-through holes 38 extend from each of the axial end faces 22, 22 to an intermediate region in the axial direction. Each non-through hole 38 is formed in a pair, with the inner tubular metal member 12 sandwiched between them, in an arc-shaped configuration that convex outward in the second radial direction. Each non-through hole 38 extends circumferentially in approximately one-eighth of the circumference of the radially outer portion (toward the outer tubular metal member 14) of the rubber elastic body 16, and is positioned opposite each other in one radial direction (left-right direction in Figure 1) across the inner tubular metal member 12. At the intermediate region in the circumferential direction, the non-through holes 38 extend circumferentially with a constant radial width (hole diameter) that is approximately one-quarter the radial thickness of the rubber elastic body 16. The circumferential end portions 40, 40 of each non-through hole 38 are curved surfaces with a gradually decreasing radial width dimension (hole diameter). Each non-through hole 38 extends axially inward from each of the axial end faces 22, 22 with a constant radial width dimension (hole diameter), and the bottoms 42, 42 are curved surfaces with a gradually decreasing radial width dimension (hole diameter). The space between the bottoms 42 of the non-through holes 38 that face each other in the axial direction forms an elastic connecting portion 34 that connects the inner cylindrical member 12 and the outer cylindrical member 14. The radial width dimension (hole diameter) at the circumferential intermediate portion of each non-through hole 38 is approximately half the radial width dimension (hole diameter) at the circumferential intermediate portion of each hollow portion 24.

The inner tubular fitting 12 side of each non-through hole 38 is formed with an inner rubber 44 that is adhered to the inner tubular fitting 12 and protrudes radially outward from the inner tubular fitting 12 side, and an outer rubber 46 that is adhered to the outer tubular fitting 14 and protrudes radially inward from the outer tubular fitting 14 side. The protruding tip surfaces of the inner rubber 44 and outer rubber 46 are positioned opposite each other at a predetermined radial distance, sandwiching each non-through hole 38 between them.

Although not explicitly shown in the drawings, the bushing 10 constructed as described above is, for example, fitted at the attachment site of the suspension arm to the vehicle frame with its central axis extending approximately vertically by inserting and securing a rod fixed to the vehicle body frame through the inner hole of the inner tubular metal fitting 12, while the outer tubular metal fitting 14 is press-fitted into an arm eye formed on the suspension arm, such as an L-shaped arm or trailing arm.

In this bushing 10, the pair of hollow portions 24, 24 sets a large radial spring ratio, resulting in soft spring characteristics in the first radial direction where the hollow portions 24, 24 face each other, and hard spring characteristics in the second radial direction perpendicular to that direction.

As shown in Figures 1 and 2, a pair of arc-shaped non-through holes 38, 38 extending axially between the inner tubular member 12 and the outer tubular member 14 are formed on both sides of the inner tubular member 12 in the second radial direction, which is perpendicular to the opposing direction of the pair of hollow portions 24, 24.

By forming a pair of arc-shaped non-through holes 38 in the second radial direction perpendicular to the opposing direction of the hollow portions 24, the spring constant ratio between the first radial direction (outline direction) and the second radial direction (solid direction) can be tuned with high precision, for example, by changing the shape (width and depth dimensions) of the non-through holes 38. Furthermore, by making the diameter of the non-through holes 38 smaller than the diameter of the hollow portions 24, the spring constant in the second radial direction (solid direction) can be reduced while maintaining a low spring constant in the first radial direction (outline direction), thereby satisfying the vehicle's required performance. Furthermore, by making the non-through holes 38 arc-shaped, stress generated in the non-through holes 38 can be reduced when a torsional input is applied, preventing a decrease in durability.

In addition, because the non-through holes 38 can be set on the outer tubular fitting 14 side, which has a larger rubber volume, the spring constant in the second radial direction (solid direction) can be efficiently lowered while maintaining the spring constant in the first radial direction (outer diameter direction). Furthermore, when an input is applied in the first radial direction (outer diameter direction) or torsional direction, because the non-through holes 38 are positioned on the outer tubular fitting 14 side, which has a longer circumferential length, the stress generated in the non-through holes 38 can be reduced, preventing a decrease in durability.

The outer peripheral shape of the inner tubular member 12 is circular, and when viewed axially, the outer peripheral circle of the inner tubular member 12 and a first inscribed circle, defined as a circle tangent to each of the inner edges of the pair of non-through holes 38, are concentric. This allows the non-through holes 38 to be efficiently positioned on the outer tubular member side, which has a larger rubber volume, thereby efficiently lowering the spring constant in the second radial direction (solid direction) while maintaining the spring constant in the first radial direction (outline direction).

In this embodiment, a protrusion 48 is located on each of the pair of elastic connecting portions 34. As shown in Figures 1 and 2, these protrusions 28 are located at a distance from the outer peripheral surface of the inner tubular fitting 12 toward the outer tubular fitting 14, and are located on the inner tubular fitting 12 side at a predetermined distance from the non-through holes 38. The pair of protrusions 48 are formed at a distance on one side in the first radial direction from the parting line that divides the inner tubular fitting in two in the second radial direction. The outer edge of the protrusions 48 is formed at a predetermined distance from the parting line. This reduces the impact of the protrusions 48 on durability.

Furthermore, since the protrusion 48 is located on the inner cylindrical member 12 side and the blind hole 38 is located on the outer cylindrical member 14 side, the radial space of the rubber elastic body 16 can be used efficiently.

The inner tubular metal fitting 12 extends at different lengths from both axial end faces 22, 22 of the rubber elastic body 16. The length of the inner tubular metal fitting 12 from one end face 22 of the rubber elastic body 16 is short, while the length of the inner tubular metal fitting 12 from the other end face 22 of the rubber elastic body 16 is long. Furthermore, a protrusion 48 is formed on one end face 22 of the rubber elastic body 16 in the area facing the inner edge of the blind hole 38 and the outer surface of the inner tubular metal fitting 12. The bushing 10 is assembled by axially press-fitting the outer tubular metal fitting 14 into an arm eye formed on a suspension arm. Because the length of the inner tubular metal fitting 12 is shortened on the side where the protrusion 48 is formed, careful consideration must be given to the method of assembling the bushing 10 to the arm eye. Since the protrusion 48 described above functions as an identification protrusion, incorrect assembly can be prevented, for example, by assembling the axial end face 22 of the rubber elastic body 16 where the protrusion 48 is formed, facing upward on the vehicle.

Although the embodiments of the present invention have been described above, the present invention should not be interpreted as being limited by the specific descriptions in these embodiments, and can be implemented in various forms with various changes, modifications, improvements, etc. based on the knowledge of those skilled in the art.

Furthermore, the shape (hole diameter and depth) of the non-through holes 38 is determined appropriately depending on the vibration-damping performance required of the bushing 10, and is not limited in any way.

Furthermore, it is not necessary to form the inclined surfaces 36, 36 on the elastic connecting portion 34, and the rubber elastic body 16 may be formed with a substantially constant thickness in the circumferential direction.

Furthermore, the installation direction of the bushing 10 is not limited, and can be appropriately set taking into account the relative position of the recessed portion 24, etc., so as to advantageously achieve the required spring characteristics and vibration-damping performance in the direction of the main radial load input.

In addition, the outer peripheral surface of the inner tubular member 12 and the inner peripheral surface of the outer tubular member 14 can also be elliptical or other shapes in cross section perpendicular to the axis. In this embodiment, the inner shaft member is cylindrical like the inner tubular member 12, but a rod shape is also possible.

In addition, although we will not list them all, the present invention can be implemented in various forms with various changes, modifications, improvements, etc. based on the knowledge of those skilled in the art, and it goes without saying that all such embodiments are included within the scope of the present invention as long as they do not deviate from the spirit of the present invention.

10...Suspension bushing, 12...Inner cylindrical metal fitting, 14...Outer cylindrical metal fitting, 16...Rubber elastic body, 22...Axial end surface, 24...Hollow portion, 26...Inner circumferential side stopper rubber, 28...Outer circumferential side stopper rubber, 30...Rubber winding portion, 32...Circumferential direction end surface, 34...Elastic connecting portion, 36...Inclined surface
38... non-through hole, 40... circumferential end portion, 42... bottom portion, 44... inner rubber, 46... outer rubber, 48... protrusion

Claims (5)

an inner shaft member;
an outer cylindrical member disposed radially outward of the inner shaft member;
a rubber elastic body connecting the inner shaft member and the outer cylindrical member;
Equipped with
The rubber elastic body is
a pair of hollow portions disposed opposite to each other across the inner shaft member in a first radial direction and penetrating the inner shaft member in an axial direction;
a pair of blind holes that are arranged opposite to each other in a second radial direction perpendicular to the first radial direction, extend from both end surfaces in the axial direction to an intermediate region in the axial direction, and are formed in an arc shape that convex outward in the second radial direction;
and
a hole diameter in the second radial direction of the pair of non-through holes is set to be smaller than a hole diameter in the first radial direction of the pair of hollow portions,
Each of the pair of non-through holes is disposed on the outer cylindrical member side.
Suspension bushing. When viewed from the axial direction, the outer circumferential shape of the inner shaft member is circular,
2. The suspension bushing according to claim 1, wherein, when viewed from the axial direction, an outer circumferential circle of the inner shaft member and a first inscribed circle defined as a circle tangent to each of the inner edges of the pair of non-through holes are concentric circles. The pair of hollow portions are formed on arcs that are convex outward in the first radial direction,
3. The suspension bushing according to claim 2 , wherein, when viewed from the axial direction, the first inscribed circle and a second inscribed circle defined as a circle tangent to each of the inner edges of the pair of hollow portions are concentric circles. the inner shaft member extends by different lengths from both end surfaces of the rubber elastic body in the axial direction,
A suspension bushing as described in any one of claims 1 to 3, wherein the rubber elastic body has a protrusion formed on one end face in the axial direction in an area facing the inner edge of at least one of the pair of non-through holes and the inner shaft member. 5. The suspension bushing according to claim 4, wherein the protrusion is formed at a position spaced apart on one side in the first radial direction from a dividing line that divides the inner shaft member into two in the second radial direction.