JP2021050761A - Suspension bush - Google Patents

Abstract

To provide a suspension bush with improved durability.SOLUTION: A suspension bush 1 comprises an inner cylinder 2, an outer cylinder 3, and an elastic body 4 that connects the inner cylinder 2 and the outer cylinder 3. In the bush 1, one end 2a in an axial direction is arranged inside vehicle mounting, and the other end 2b in the axial direction is arranged outside the vehicle mounting. In an axial central region Rc of the inner cylinder 2, an outer peripheral surface 21 of the inner cylinder 2 is provided with an outer peripheral surface side inclined part 211 in which an outer diameter φ1 becomes smaller from the one end 2a side in the axial direction toward the other end 2b side in the axial direction, and an inner peripheral surface 22 of the inner cylinder 2 is provided with an inner peripheral surface side inclined part 221 in which an inner diameter φ2 becomes larger from the one end 2a side in the axial direction to the other end 2b side in the axial direction.SELECTED DRAWING: Figure 1

Description

The present invention relates to a suspension bush.

In some conventional suspension bushes, the outer peripheral surface of the inner cylinder has a straight shape along the axial direction, and the inner cylinder and the outer cylinder are connected by an elastic body (see, for example, Patent Document 1).

Japanese Unexamined Patent Publication No. 2012-202460

However, in the conventional suspension bush, a crack is generated in the elastic body from the adhesive surface between the inner cylinder and the elastic body in the vicinity of the central region in the axial direction of the inner cylinder, and the crack is generated on the outside of the vehicle mounting. There was a case where it progressed toward. That is, the conventional suspension bush has room for improvement in terms of durability.

An object of the present invention is to provide a suspension bush having improved durability.

The suspension bush according to the present invention includes an inner cylinder, an outer cylinder, and an elastic body connecting the inner cylinder and the outer cylinder, and one end of the inner cylinder in the axial direction is arranged inside the vehicle mounting. A suspension bush in which the other end in the axial direction of the inner cylinder is arranged outside the vehicle mounting, and the inner cylinder is formed on the outer peripheral surface of the inner cylinder in the axial central region of the inner cylinder. An outer peripheral surface side inclined portion whose outer diameter becomes smaller from one end side in the axial direction of the inner cylinder toward the other end side in the axial direction of the inner cylinder is provided, and the inner peripheral surface of the inner cylinder is formed by the inner cylinder. The inner peripheral surface side inclined portion is provided so that the inner diameter increases from one end side in the axial direction of the inner cylinder toward the other end side in the axial direction of the inner cylinder. According to the suspension bush according to the present invention, the suspension bush has improved durability.

In the suspension bush according to the present invention, it is preferable that the outer peripheral surface side inclined portion is arranged on the one end side in the axial direction of the inner cylinder rather than the inner peripheral surface side inclined portion. In this case, the durability can be further improved.

In the suspension bush according to the present invention, the inclination angle of the outer peripheral surface side inclined portion on the acute angle side with respect to the axis is larger than the inclination angle of the inner peripheral surface side inclined portion on the acute angle side with respect to the axis line in the axial cross-sectional view. Larger is preferred. In this case, the durability can be further improved.

The suspension bush according to the present invention is preferably a trailing arm bush. In this case, more effective improvement in durability can be realized.

According to the present invention, it is possible to provide a suspension bush having improved durability.

It is a top view which shows the suspension bush of one Embodiment which concerns on this invention. FIG. 1 is a cross-sectional view taken along the line AA of FIG. It is sectional drawing which shows the area X of FIG. 2 enlarged. It is a top view which shows typically an example of the suspension mechanism of a vehicle which can adopt the suspension bush of FIG. FIG. 5 is a cross-sectional view showing a conventional suspension bush corresponding to the AA cross section of FIG.

Hereinafter, the suspension bush of one embodiment according to the present invention will be described with reference to the drawings.

In FIG. 1, reference numeral 1 is a suspension bush according to an embodiment of the present invention. The suspension bush 1 includes an inner cylinder 2, an outer cylinder 3, and an elastic body 4 that connects the inner cylinder 2 and the outer cylinder 3.

In the present embodiment, the inner cylinder 2 and the outer cylinder 3 are arranged on the same axis O. The inner cylinder 2 and the outer cylinder 3 are made of a metal such as carbon steel or an aluminum alloy. Further, the elastic body 4 is made of rubber. However, the elastic body 4 can be formed of an elastic material other than rubber.

Two cutting holes (through holes) 5 are formed in the elastic body 4. As shown in FIG. 1, the two torn holes 5 are formed at positions facing each other with the inner cylinder 2 interposed therebetween in a plan view. The curl hole 5 extends along the axis O and penetrates the elastic body 4. Further, the elastic body 4 is provided with two stoppers 4a.

Referring to FIG. 2, the suspension bush 1 is a suspension bush in which one end 2a in the axial direction of the inner cylinder 2 is arranged inside the vehicle mounting and the other end 2b in the axial direction of the inner cylinder 2 is arranged outside the vehicle mounting. is there.

FIG. 4 is a plan view schematically showing an example of a suspension mechanism 100 in which the suspension bush 1 can be adopted. The suspension mechanism 100 of this example is a torsion beam type suspension mechanism arranged on the rear side of the vehicle. In this example, the suspension mechanism 100 includes two trailing arms 110 arranged at intervals in the vehicle width direction and one torsion beam 120 extending in the vehicle width direction. In this example, the two trailing arms 110 extend in the front-rear direction of the vehicle, respectively. Further, the two trailing arms 110 are integrally connected by a torsion beam 120, respectively. In this example, the outer cylinder 3 of the suspension bush 1 is attached to the front end portion 110a of the trailing arm 110. Further, in this example, the inner cylinder 2 of the suspension bush 1 is connected to the fixing portion 130 provided on the vehicle body side. That is, the trailing arm 110 is connected to the vehicle side via the suspension bush 1. Further, the rear wheel 140 is rotatably connected to the rear end portion 110b of the trailing arm 110. In this example, the suspension bush 1 mainly functions as a compliance bush.

Here, referring to FIG. 2, the inner cylinder 2 is provided with an outer peripheral surface side inclined portion 211 on the outer peripheral surface 21 of the inner cylinder 2 in the axial central region Rc of the inner cylinder 2. The outer peripheral surface side inclined portion 211 forms a part of the outer peripheral surface 21 of the inner cylinder 2. Referring to FIG. 3, in the outer peripheral surface side inclined portion 211, the outer diameter of the inner cylinder 2 is from the axial end 2a side of the inner cylinder 2 (hereinafter, also referred to as “axial one end side”) to the inner cylinder 2. It becomes smaller as it goes toward the other end 2b side in the axial direction (hereinafter, also referred to as "the other end side in the axial direction"). Specifically, the outer peripheral surface side inclined portion 211 becomes smaller at a constant ratio (angle θ1) as the outer diameter dimension φ211 of the outer peripheral surface side inclined portion 211 goes from one end side in the axial direction to the other end side in the axial direction. There is. That is, the outer peripheral surface side inclined portion 211 is an annular tapered surface surrounding the shaft O, which is tapered at a constant angle θ1 as it goes toward the other end side in the axial direction. Here, as shown in FIG. 3, the angle θ1 is an acute-angled angle formed by the axis O and the outer peripheral surface side inclined portion 211 in an axial cross-sectional view (a state of being viewed in a cross section including the axis O).

Further, referring to FIG. 2, the inner cylinder 2 is provided with an inner peripheral surface side inclined portion 221 on the inner peripheral surface 22 of the inner cylinder in the axial central region Rc of the inner cylinder 2. The inner peripheral surface side inclined portion 221 forms a part of the inner peripheral surface 22 of the inner cylinder 2. With reference to FIG. 3, the inner peripheral surface side inclined portion 221 has an inner diameter φ2 of the inner cylinder 2 as an axis. It increases from one end side in the direction toward the other end side in the axial direction. Specifically, the inner peripheral surface side inclined portion 221 is increased at a constant ratio (angle θ2) as the outer diameter dimension φ221 of the inner cylinder 2 is directed from one end side in the axial direction to the other end side in the axial direction. That is, the inner peripheral surface side inclined portion 221 is an annular tapered surface surrounding the axis O, which is enlarged at a constant angle θ2 as it goes toward the other end side in the axial direction. Here, as shown in FIG. 3, the angle θ2 is an acute-angled angle formed by the axis O and the inner peripheral surface side inclined portion 221 in the axial cross-sectional view.

The suspension bush has not only inputs in the direction perpendicular to the axis (diameter direction orthogonal to the axis O) but also complicated inputs such as twisting and prying. Therefore, it is very difficult to ensure the durability of the elastic body 4 over a long period of time. Further, the shape of the inner cylinder 2 is limited in order to secure the spring characteristics required for the suspension bush.

However, as in the conventional suspension bush 10 shown in FIG. 5, when the outer diameter dimension φ21 of the inner cylinder 2 is constant, that is, the outer peripheral surface 21 of the inner cylinder 2 has a straight shape along the axial direction. In this case, as in the present embodiment, when the axial end 2a of the inner cylinder 2 is arranged inside the vehicle mounting and the other end 2b of the inner cylinder 2 in the axial direction is arranged outside the vehicle mounting, the suspension bush is arranged. In the vicinity of the axial central region Rc of the inner cylinder 2, a crack is generated in the elastic body 4 with the bonding surface M between the inner cylinder 2 and the elastic body 4 as a base point, as shown by an arrow C, and the crack is caused by the vehicle. There was a case where it progressed toward the outside of the mounting.

Therefore, as a result of diligent tests and research, the inventor of the present application has found that the cause of the crack is the elastic body 4 of the adhesive surface M with the inner cylinder 2 on the outer side of the vehicle mounting in the axial central region Rc of the inner cylinder 2. It was confirmed that the stress was generated by being pulled toward.

On the other hand, as shown in FIG. 2, in the suspension bush 1 according to the present embodiment, as described above, the inner cylinder 2 is placed on the outer peripheral surface 21 of the inner cylinder 2 in the axial central region Rc. The outer peripheral surface side inclined portion 211 is provided, in which the outer diameter of 2 decreases from one end side in the axial direction toward the other end side in the axial direction. In this case, of the volume amount of the elastic body 4 interposed between the inner cylinder 2 and the outer cylinder 3 (hereinafter, also referred to as “rubber volume” in the present embodiment), the other end of the inner cylinder 2 in the axial direction. A larger volume amount B of the elastic body 4 interposed between the inner cylinder 2 and the outer cylinder 3 on the 2b side (hereinafter, also referred to as "the rubber volume on the other end side in the axial direction" in the present embodiment) is secured. can do.

That is, according to the suspension bush 1 according to the present embodiment, by securing the rubber volume, the influence on the spring characteristics of the suspension bush 1 is minimized, and the rubber volume B on the other end side in the axial direction is increased. In the axial central region Rc of the inner cylinder 2, the stress generated between the inner cylinder 2 and the elastic body 4 can be suppressed. Therefore, according to the present embodiment, the elastic body is formed on the adhesive surface M between the inner cylinder 2 and the elastic body 4 in the axial central region Rc of the inner cylinder 2 without impairing the spring characteristics required for the suspension bush. The stress generated in 4 is relaxed. Thereby, according to the present embodiment, it is possible to suppress the generation of cracks in the elastic body 4 and the growth of the cracks.

Therefore, the suspension bush 1 according to the present embodiment is a suspension bush with improved durability.

According to the present invention, the axial central region Rc of the inner cylinder 2 is preferably a region located at the center when the total length L of the inner cylinder 2 is divided into three equal parts.

Specifically, as shown in FIG. 2, the inner cylinder 2 can be divided into three regions: an axial end region Ra, an axial central region Rc, and an axial other end region Rb. It is preferable that each of these three regions is a region when the total length L of the inner cylinder 2 is divided into three equal parts. That is, when the inner cylinder 2 is divided into three regions in the axial direction, the one end region Ra in the axial direction, the central region Rc in the axial direction, and the other end region Rb in the axial direction respectively have the inner cylinder 2 as the total length of the inner cylinder 2. It is each area when it is divided equally by the length (L / 3) of 1/3 of L.

As shown in FIG. 2, in the present embodiment, the axial central region Rc of the inner cylinder 2 is a region located at the center when the total length L of the inner cylinder 2 is divided into three equal parts. When the outer peripheral surface side inclined portion 211 is provided on the axial one end 2a side of the axial central region Rc, that is, when the outer peripheral surface side inclined portion 211 is provided on the axial one end region Ra, the axial other end side rubber volume If B increases too much, the original spring characteristics of the suspension bush will deteriorate, and there is a concern that the required spring characteristics cannot be maintained with the hardness of the elastic body equivalent to the conventional one. On the other hand, when the outer peripheral surface side inclined portion 211 is provided on the axially opposite end 2b side of the axial central region Rc, that is, when the outer peripheral surface side inclined portion 211 is provided on the axially opposite end region Rb, the shaft There is concern that the increase in the rubber volume B on the other end side in the direction will be insufficient, and the effects of the present invention such as stress relaxation and durability improvement will not be sufficiently exhibited.

Therefore, if the axial central region Rc of the inner cylinder 2 is a region located at the center when the total length L of the inner cylinder 2 is divided into three equal parts as in the present embodiment, the suspension bush It is possible to effectively improve the durability without impairing the required spring characteristics.

By the way, the suspension bush is required to be lightweight for the purpose of improving fuel efficiency and the like. Further, in the suspension bush in which the axial end 2a of the inner cylinder 2 is arranged so as to face the vehicle mounting inside as in the present embodiment, the suspension bush is an opening formed in the axial end 2a of the inner cylinder 2. It is assembled to the vehicle by arranging a fastening element such as a screw in the portion 2c. Therefore, if the inner diameter dimension φ2a of one end 2a in the axial direction of the inner cylinder 2 becomes too large, there is a possibility that rattling may occur after the suspension bush is mounted on the vehicle. Therefore, it is preferable that the inner diameter dimension φ2a of one end 2a in the axial direction of the inner cylinder 2 is kept small.

In the suspension bush 1 according to the present embodiment, the inner cylinder 2 has the inner diameter φ2 of the inner cylinder 2 axially from one end side in the axial direction on the inner peripheral surface 22 of the inner cylinder 2 in the axial central region Rc of the inner cylinder 2. The inner peripheral surface side inclined portion 221 that increases toward the other end side is provided. In this case, it is possible to increase the inner diameter dimension φ2b of the axial end 2b of the inner cylinder 2 without increasing the inner diameter dimension φ2a of the axial end 2a of the inner cylinder 2.

That is, according to the suspension bush 1 according to the present embodiment, the thickness of the inner cylinder 2 on the axial end 2b side of the inner cylinder 2 is reduced while keeping the size of the inner diameter φ2a of the axial end 2a of the inner cylinder 2 small. be able to. Therefore, according to the suspension bush 1 according to the present embodiment, the weight of the inner cylinder 2 can be reduced while suppressing the rattling that may occur after the vehicle is mounted, thereby reducing the weight of the suspension bush 1 as a whole and after mounting the vehicle. It is possible to achieve both the suppression of rattling and the suppression of rattling.

In addition, to explain with reference to FIG. 3, in the outer peripheral surface side inclined portion 211 of the inner cylinder 2, the outer diameter dimension φ211a of the axial end end 211a of the outer peripheral surface side inclined portion 211, and the outer peripheral surface side inclined portion 211. The outer diameter dimension difference Δφ211 (= φ211a−φ211b) of the other end 211b in the axial direction from the outer diameter dimension φ211b is a value within 20% of the outer diameter dimension φ211a of the axial end end 211a of the outer peripheral surface side inclined portion 211. Is preferable.

Further, referring to FIG. 2, in the suspension bush according to the present invention, it is preferable that the outer peripheral surface side inclined portion 211 is arranged on one end side in the axial direction with respect to the inner peripheral surface side inclined portion 221. In this case, by moving the outer peripheral surface side inclined portion 211 toward one end side in the axial direction, the rubber volume Bb on the other end side in the axial direction is increased, and the inner peripheral surface side inclined portion 221 is moved toward the other end side in the axial direction. It is possible to limit the axial region in which the wall thickness on the other end side of the inner cylinder 2 in the axial direction becomes thin. In this case, the durability of the elastic body 4 can be improved by suppressing the stress generated between the inner cylinder 2 and the elastic body 4, and the durability of the inner cylinder 2 is ensured by ensuring the wall thickness of the inner cylinder 2. The sex can be improved. Thereby, the durability of the suspension bush 1 can be further improved.

As shown in FIG. 3, in the present embodiment, the outer peripheral surface side inclined portion 211 is arranged on one end side in the axial direction with respect to the inner peripheral surface side inclined portion 221. Therefore, according to the present embodiment, the durability of the suspension bush 1 can be further improved.

Further, the suspension bush according to the present invention has an acute angle (a straight line extending parallel to the axis O) of the outer peripheral surface side inclined portion 211 in an axial cross-sectional view (viewing with a plane including the axis O as a cross section). ), The angle θ1 on the acute angle side with respect to the axis is preferably larger than the angle θ2 on the acute angle side with respect to the axis of the inner peripheral surface side inclined portion 221. In this case, by increasing the angle θ1 of the outer peripheral surface side inclined portion 211, the angle θ2 of the inner peripheral surface side inclined portion 221 is changed to the angle of the outer peripheral surface side inclined portion 211 while increasing the rubber volume B on the other end side in the axial direction. By suppressing the thickness to less than θ1, the amount of thinning of the wall thickness t on the other end 2b side of the inner cylinder 2 in the axial direction can be limited. In this case, the durability of the elastic body 4 can be improved by suppressing the stress generated between the inner cylinder 2 and the elastic body 4, and the durability of the inner cylinder 2 is ensured by ensuring the wall thickness of the inner cylinder 2. The sex can be improved. Thereby, the durability of the suspension bush 1 can be further improved.

As shown in FIG. 3, in the present embodiment, the angle θ1 of the outer peripheral surface side inclined portion 211 is larger than the angle θ2 of the inner peripheral surface side inclined portion 221 in the axial cross-sectional view. Therefore, according to the present embodiment, the durability of the suspension bush 1 can be further improved.

Further, the suspension bush according to the present invention is preferably a trailing arm bush as described above. In this case, since it is used as a bush of the trailing arm 110 in which the load is input in a complicated manner, more effective improvement in durability can be realized.

The suspension bush 1 according to the present embodiment is a trailing arm bush mounted on the trailing arm 110 constituting the suspension mechanism. Therefore, according to the present embodiment, more effective improvement in durability can be realized.

As described above, according to the present invention, it is possible to provide the suspension bush 1 having improved durability.

1: Suspension bush (trailing arm bush), 2: Inner cylinder, 2a: One end in the axial direction of the inner cylinder, 2b: The other end in the axial direction of the inner cylinder, 3: Outer cylinder, 4: Elastic body, 21: Inner cylinder Outer peripheral surface, 211: Outer peripheral surface side inclined portion, 22: Inner peripheral surface side inclined portion, 221: Inner peripheral surface side inclined portion, θ1: Outer peripheral surface side inclined portion sharp angle side, θ2: Inner peripheral surface side inclined portion Angle on the sharp angle side, φ211a: Outer diameter dimension of the axial end of the outer peripheral surface side inclined portion, φ211b: Outer diameter dimension of the axial other end of the outer peripheral surface side inclined portion, Ra: Axial end diameter dimension of the inner cylinder, Rc : Axial center region of inner cylinder, Rb: Axial other end region of inner cylinder, O: Axis (axis)

Claims (4)

An inner cylinder, an outer cylinder, and an elastic body connecting the inner cylinder and the outer cylinder are provided, and one end in the axial direction of the inner cylinder is arranged inside the vehicle mounting and the other end in the axial direction of the inner cylinder. Is a suspension bush that is placed on the outside of the vehicle.
The inner cylinder is formed in the axially central region of the inner cylinder.
The outer peripheral surface of the inner cylinder is provided with an inclined portion on the outer peripheral surface side in which the outer diameter of the inner cylinder decreases from one end side in the axial direction of the inner cylinder toward the other end side in the axial direction of the inner cylinder.
The inner peripheral surface of the inner cylinder is provided with an inner peripheral surface-side inclined portion in which the inner diameter of the inner cylinder increases from one end side in the axial direction of the inner cylinder toward the other end side in the axial direction of the inner cylinder. , Suspension bush. The suspension bush according to claim 1, wherein the outer peripheral surface side inclined portion is arranged on the one end side in the axial direction of the inner cylinder with respect to the inner peripheral surface side inclined portion. According to claim 1 or 2, the inclination angle of the outer peripheral surface side inclined portion on the acute angle side with respect to the axis is larger than the inclination angle of the inner peripheral surface side inclined portion on the acute angle side with respect to the axis line in the axial cross-sectional view. The suspension bush described. The suspension bush according to any one of claims 1 to 3, wherein the suspension bush is a trailing arm bush.

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