Vibration isolation device

Abstract

To provide a vibration controller capable of improving a static spring constant of a bush in a direction perpendicular to an axis while suppressing increase in volume of the bush.SOLUTION: A lower pedestal 24 is formed on an end surface of a bush 20 in an axial direction at a position below a through hole 21. The lower pedestal 24 inclines an outer peripheral surface 22 of the bush 20 outward in the axial direction as it goes downward. The lower pedestal 24 can improve a static spring constant of the bush 20 against downward compressive deformation while suppressing increase in volume of the bush 20.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a vibration isolator, and particularly to a vibration isolator that can improve the static spring constant in the direction perpendicular to the axis of the bush while suppressing an increase in the volume of the bush.

Background Art

[0002] For example, a vibration isolator that connects a shaft-shaped first member such as a stabilizer bar and a cylindrical second member such as a bracket with a cylindrical bush made of an elastic body is known. The first member is inserted into a through hole provided in the center of the bush, and the bush is compressed in the direction perpendicular to the axis while the outer peripheral surface of the bush is in contact with the second member. The bush disclosed in Patent Document 1 has, in the unloaded state, one end surface in the axial direction formed flat and the inner peripheral surface (through hole) side of the other end surface in the axial direction protruding in the axial direction.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, when the bush is compressed in the direction perpendicular to the axis as in the above prior art and the end surface in the axial direction of the bush is flat, the end surface in the axial direction bulges at the central portion between the inner peripheral surface and the outer peripheral surface. This bulged portion hardly affects the static spring constant of the bush and increases the volume of the bush. Similarly, even when the inner peripheral surface side of the end surface in the axial direction is made to protrude, the portion that bulges outside the axial direction from the contact surface between the outer peripheral surface of the bush and the second member hardly affects the static spring constant and increases the volume of the bush.

[0005] The present invention was made to solve the above-mentioned problems, and aims to provide a vibration isolation device that can improve the static spring constant of the bush perpendicular to its axis while suppressing an increase in the volume of the bush. [Means for solving the problem]

[0006] To achieve this objective, the vibration isolation device of the present invention is composed of an elastic body that is compressed perpendicular to the axis between the outer circumferential surface of a shaft-shaped first member and the inner circumferential surface of a cylindrical second member, and includes a cylindrical bush surrounding the shaft. The bush includes a through hole into which the first member can be inserted and which forms the inner circumferential surface of the bush, and a first base formed at a position in a first direction perpendicular to the axis with respect to the through hole on at least one end face in the axial direction of the bush. The first base is inclined outward in the axial direction as it approaches the first direction, up to the outer circumferential surface of the bush that can contact the second member. [Effects of the Invention]

[0007] According to the vibration isolation device described in claim 1, a first base is formed on at least one axial end face of the bush at a position in a first direction relative to the through hole. This first base is inclined outward in the axial direction as it approaches the first direction, up to the outer circumferential surface of the bush that can contact the second member. This first base makes it difficult for one axial end face of the bush to bulge in the central part between the inner and outer circumferential surfaces, and also increases the contact area between the outer circumferential surface of the bush and the second member. As a result, the static spring constant of the bush against compressive deformation in the first direction can be improved while suppressing an increase in the volume of the bush.

[0008] The vibration isolation device according to claim 2 provides the following effects in addition to the effects of the vibration isolation device according to claim 1. The first base is formed on both axial end faces of the bush. This makes it possible to further improve the static spring constant of the bush in the first direction while suppressing an increase in the volume of the bush.

[0009] The vibration isolation device according to claim 3 provides the following effects in addition to the effects of the vibration isolation device according to claim 1. A second base is formed on at least one end face of the bush in the axial direction at a position in a second direction opposite to the first direction with respect to the through hole. The second base is inclined outward in the axial direction as it approaches the second direction, up to the outer circumferential surface of the bush that can contact the second member. Similar to the first base, this second base can improve the static spring constant of the bush against compressive deformation in the second direction while suppressing an increase in the volume of the bush.

[0010] The vibration isolation device according to claim 4 provides the following effects in addition to the effects of the vibration isolation device according to claim 1. A first base is formed on the axial end face of the bush over its entire length in the axial direction and in a third direction perpendicular to the first direction. This makes it difficult for the bush to slide axially against the second member over its entire length in the third direction when the bush is compressed in the first direction, for example, when the outer circumferential surface of the bush is not adhered to the inner circumferential surface of the second member. This reduces changes in the static spring constant of the bush caused by such sliding.

[0011] The vibration isolation device according to claim 5 provides the following effects in addition to the effects of the vibration isolation device according to claim 1. The first base has the same cross-sectional shape over its entire length in the axial direction and in a third direction perpendicular to the first direction. This makes it easier to mold the bush using a mold that cracks in the third direction.

[0012] The vibration isolation device according to claim 6 provides the following effects in addition to the effects of the vibration isolation device according to claim 1. The axial end face of the bush has a flat surface perpendicular to the axis of the bush. The boundary between this flat surface and the first base is a straight line perpendicular to the first direction in an axial view and is tangent to the inner edge of the through hole. This allows the first base to be provided in a part that easily contributes to improving the static spring constant of the bush in the first direction, while the part that contributes less can be made into a flat surface. As a result, a good balance can be achieved between reducing the volume of the bush and improving the static spring constant of the bush in the first direction.

[0013] The vibration isolation device described in claim 7 provides the following effects in addition to the effects of the vibration isolation device described in any of claims 1 to 6. The vibration isolation device includes a second member that contacts the outer circumferential surface of the bush. Since the outer circumferential surface of the bush is not adhered to the second member, the bush, which has been compressed and deformed in the direction perpendicular to the axis, may slide axially against the second member as it expands to escape in the axial direction. However, even when the bush is compressed and deformed in the first direction, the inclination of the first base, which widens on the second member side, makes it difficult for the bush to slide axially against the second member. This reduces changes in the static spring constant of the bush caused by such sliding. [Brief explanation of the drawing]

[0014] [Figure 1] This is a perspective view of the bushing of the vibration isolation device in the first embodiment. [Figure 2] This is a front view of the bush. [Figure 3] Figure 2 shows a cross-sectional view of the bush along the line III-III. [Figure 4] This is a cross-sectional view of a vibration isolation device in which bushings are assembled to a stabilizer bar and bracket. [Figure 5] (a) is a front view of the bush of the vibration isolation device in the second embodiment, and (b) is a bottom view of the bush as seen in the direction of arrow Vb in Figure 5(a). [Figure 6] Figure 5(a) is a cross-sectional view of the bush along the line VI-VI. [Figure 7] This is a front view of the bushing of the vibration isolation device in the third embodiment. [Figure 8] (a) is a cross-sectional view of the bush along the line VIIIa-VIIIa in Figure 7, and (b) is a cross-sectional view of the bush along the line VIIIb-VIIIb in Figure 7. [Figure 9] (a) is a front view of the bush of the vibration isolation device in the fourth embodiment, and (b) is a cross-sectional view of the bush along the line IXb-IXb in Figure 9(a). [Figure 10](a) is a cross-sectional view of the bush along the Xa-Xa line in Fig. 9(a), and (b) is a cross-sectional view of the bush along the Xb-Xb line in Fig. 9(a).

Embodiments for Carrying out the Invention

[0015] Hereinafter, preferred embodiments will be described with reference to the accompanying drawings. Fig. 1 is a perspective view of the bush 20 of the vibration isolator 10 (see Fig. 4) in the first embodiment. Fig. 2 is a front view of the bush 20. Fig. 3 is a cross-sectional view of the bush 20 along the III-III line in Fig. 2.

[0016] The arrows U, D, L, R, F, and B in each drawing indicate the upward, downward, leftward, rightward, forward, and backward directions of the bush 20, respectively. The vertical direction, the horizontal direction, and the front-back direction are perpendicular to each other. Also, the bush 20 in Figs. 1 to 3 all show a no-load state where no load other than gravity is applied. In the description using Figs. 1 to 3, unless otherwise specified, the bush 20 in the no-load state will be described.

[0017] As shown in Figs. 1 and 2, the bush 20 is a cylindrical member surrounding the axis C and is composed of an elastic body such as rubber or thermoplastic elastomer. In this specification, the direction parallel to the axis C is simply referred to as the axial direction, and the direction perpendicular to the axis C is referred to as the axis-perpendicular direction. Note that the front-back direction of the bush 20 is the same as the axial direction, and the vertical and horizontal directions of the bush 20 are part of the axis-perpendicular direction.

[0018] A through-hole 21 forming the inner peripheral surface of the bush 20 penetrates axially through the bush 20. This through-hole 21 is circular with the axis C as the center in the axial view (Fig. 2). The radius from the axis C to the inner peripheral surface of the through-hole 21 is substantially the same throughout the entire circumference.

[0019] In an axial view, the outer circumferential surface 22 of the bush 20 is formed such that the upper half is an arc shape centered on axis C, and the lower half is rectangular. In other words, the outer circumferential surface 22 is formed in an inverted U shape in an axial view. Furthermore, a concave surface 22a is formed on almost the entire circumference of the outer circumferential surface 22, except for the bottom surface, with the central part in the axial direction recessed inward in the direction perpendicular to the axis.

[0020] Furthermore, the axial end of the outer peripheral surface 22 is formed by a curved surface 22b that smoothly connects with the axial end face of the bush 20. That is, the curved surface 22b is inclined toward the axial center as it moves away from the axial end face of the bush 20 in a direction perpendicular to the axis.

[0021] As shown in Figures 1 and 3, the axial end face of the bush 20 is formed by a flat surface 23 perpendicular to the axis C, and a lower base (first base) 24 and an upper base (second base) 26 that are inclined outward in the axial direction as they move away from the through hole 21. In this embodiment of the bush 20, both axial end faces are formed identically to each other.

[0022] The flat surfaces 23 are provided on both sides of the through hole 21 in the left-right direction. The lower base 24 is provided in a position below the through hole 21 (first direction). The upper base 26 is provided in a position above the through hole 21 (second direction). Figure 3 shows the case where the flat surfaces 23 are extended on both sides in the vertical direction relative to the through hole 21, indicated by dashed lines.

[0023] The lower base 24 is inclined outward in the axial direction as it extends downward to the curved surface 22b of the outer circumferential surface 22 of the bush 20. The upper base 26 is inclined outward in the axial direction as it extends upward to the curved surface 22b. The inclination angle of the upper base 26 relative to the flat surface 23 is greater than the inclination angle of the lower base 24 relative to the flat surface 23. As a result, a portion of the upper base 26 protrudes outward in the axial direction relative to the lower base 24.

[0024] As shown in Figure 2, the boundary 25 between the flat surface 23 and the lower base 24 is a straight line perpendicular to the vertical direction in an axial view and is tangent to the inner edge of the through hole 21. The boundary 27 between the flat surface 23 and the upper base 26 is a straight line perpendicular to the vertical direction in an axial view and is tangent to the inner edge of the through hole 21. That is, in an axial view, the tangent at the lowest point L on the inner edge of the through hole 21 is boundary 25, and the tangent at the highest point H on the inner edge of the through hole 21 is boundary 27. Furthermore, boundary 25 is the starting point of the inclination of the lower base 24, and boundary 27 is the starting point of the inclination of the upper base 26.

[0025] The lower base 24 and the upper base 26 are formed along the entire length of the bush 20 in the left-right direction (third direction) on the axial end face. Furthermore, the lower base 24 and the upper base 26 have the same cross-sectional shape perpendicular to the left-right direction along their entire length in the left-right direction. This makes it easier to mold the bush 20 using a mold that splits in the center in the left-right direction.

[0026] Next, the method of using the vibration isolation device 10 including the bush 20 will be described with reference to Figure 4. Figure 4 is a cross-sectional view of the vibration isolation device 10 with the bush 20 assembled to the stabilizer bar 11 and bracket 12. In this embodiment, the vertical, horizontal, and longitudinal directions of the bush 20 coincide with the vertical, longitudinal, and horizontal directions of the vehicle on which the bush 20 is mounted, respectively. However, these directions of the bush 20 may differ from the directions of the vehicle.

[0027] The stabilizer bar 11 is a component that suppresses the rolling of the vehicle body and is positioned along the left-right direction of the vehicle. The stabilizer bar 11 is an axial steel material with a circular cross-section. This stabilizer bar 11 is inserted into the through hole 21 of the bush 20 and fitted into place, so that the outer surface of the stabilizer bar 11 and the inner surface of the bush 20 (through hole 21) are in close contact.

[0028] The vibration damping device 10 is for elastically supporting the stabilizer bar 11 on the vehicle body and comprises a bracket 12 and the bush 20 described above. The bracket 12 is a cylindrical member for assembling the bush 20 to the vehicle body while compressing the bush 20, into which the stabilizer bar 11 is inserted, in a direction perpendicular to the axis.

[0029] The bracket 12 comprises a flat plate member 13 whose bottom surface contacts the outer circumferential surface 22 of the bush 20 without adhesive, and a curved plate member 14 whose top surface and both left and right surfaces contact the outer circumferential surface 22 without adhesive. The curved plate member 14 is formed in an inverted U shape when viewed in the front-to-back direction, similar to the outer circumferential surface 22 of the bush 20. Furthermore, the inner circumferential surface of the curved plate member 14 is formed to match the shape of the concave surface 22a and curved surface 22b of the outer circumferential surface 22 of the bush 20, and is in close contact with those concave surface 22a and curved surface 22b.

[0030] When the bush 20 is inserted inside the curved plate member 14, the bush 20 is compressed in the left-right direction. Furthermore, when the flat plate member 13 and the curved plate member 14 are fastened together with a fastening member (not shown) while the bush 20 is sandwiched between the flat plate member 13 and the curved plate member 14 from above and below, the bush 20 is compressed vertically. The bracket 12 (flat plate member 13 and curved plate member 14) is also fastened to the vehicle body by this fastening member.

[0031] This state, in which the bush 20 is assembled to the stabilizer bar 11 and bracket 12, is called the assembled state of the bush 20. In this assembled state, the bush 20 is mainly compressed above and below the stabilizer bar 11, and the compressed portion expands axially compared to the unloaded state. In particular, the central part of the axial end face of the bush 20, which is far from the stabilizer bar 11 and bracket 12, tends to bulge out in the direction perpendicular to the axis.

[0032] The expansion of the bush 20 causes the portion that protrudes axially outward from the contact surface between the bush 20 and the bracket 12 in the cross-section including axis C to have little effect on the static spring constant of the bush 20 with respect to compressive deformation perpendicular to the axis, and instead increases the volume of the bush 20. The compressive deformation of the bush 20 refers to the further compression of the bush 20 perpendicular to the axis due to vibration input to the vibration isolation device 10, from the state in which the bush 20 is compressed when assembled to the stabilizer bar 11 and bracket 12.

[0033] In this embodiment, a lower base 24 and an upper base 26 are formed on the axial end face of the bush 20 at positions above and below the stabilizer bar 11 (through hole 21), where they expand axially due to vertical compression. In an unloaded state (state as shown in Figure 3, etc.), the lower base 24 and the upper base 26 are inclined outward in the axial direction up to the curved surface 22b of the outer peripheral surface 22 that contacts the bracket 12, as they move away from the stabilizer bar 11 (through hole 21) vertically.

[0034] The lower base 24 and upper base 26 make it difficult for the central part of the axial end face of the bush 20 to bulge above and below the stabilizer bar 11, and also increase the contact area between the bush 20 and the bracket 12. As a result, the static spring constant of the bush 20 against vertical compression deformation can be improved while suppressing an increase in the volume of the bush 20.

[0035] For example, to prevent the bush 20 from contacting a component located near the bracket 12, it may be necessary to prevent the bush 20 from protruding axially from the bracket 12 even when the bush 20 is compressed to its maximum extent in the vertical direction. Even if it is difficult to increase the volume of the bush 20 to achieve such a requirement, the lower base 24 and upper base 26 can improve the static spring constant of the bush 20 in the vertical direction.

[0036] The lower base 24 and the upper base 26 are formed on both axial end faces of the bush 20, respectively. Therefore, the static spring constant in the vertical direction of the bush 20 can be improved compared to the case where the lower base 24 and the upper base 26 are formed on only one axial end face.

[0037] Furthermore, the outer circumferential surface 22 of the bush 20 and the inner circumferential surface of the bracket 12 are not bonded together. As a result, the bush 20, which has been compressed and deformed perpendicular to the axis, may expand to escape in the axial direction, causing the bush 20 to slide axially relative to the bracket 12.

[0038] However, in this embodiment, the bush 20 can withstand the vertical load from the stabilizer bar 11 through the lower base 24 and upper base 26, which widen towards the contact surface with the bracket 12. Therefore, when the bush 20 is compressed and deformed in the vertical direction, it is difficult for the bush 20 to slide axially relative to the bracket 12. Thus, changes in the static spring constant of the bush 20 caused by such sliding can be reduced.

[0039] Furthermore, the lower base 24 and upper base 26 within region A, which overlaps with the through hole 21 in a vertical view, are more likely to contribute to improving the static spring constant of the bush 20 in the vertical direction, while the lower base 24 and upper base 26 outside region A are less likely to contribute. In Figure 2, the left-right edges of region A are shown by dashed lines.

[0040] However, the lower base 24 and upper base 26 outside region A can have the effect of making it difficult for the bush 20 to slide axially relative to the bracket 12. Therefore, by providing the lower base 24 and upper base 26 not only inside region A but also outside region A, the range in which the bush 20 is difficult to slide axially relative to the bracket 12 when the bush 20 is compressed and deformed in the vertical direction can be widened.

[0041] Furthermore, a lower base 24 and an upper base 26 are formed on the axial end face of the bush 20, extending along its entire length in the left-right direction. Therefore, when the bush 20 is compressed in the vertical direction, it is made difficult for the bush 20 to slide axially against the bracket 12 along its entire length in the left-right direction. Thus, changes in the static spring constant of the bush 20 caused by such sliding can be further reduced.

[0042] The shape of the part of the bush 20 directly below the lowest point L and the shape of the part directly above the highest point H contribute most to the static spring constant of the bush 20 in the vertical direction. Since a lower base 24 is provided below the lowest point L and an upper base 26 is provided above the highest point H, the static spring constant of the bush 20 in the vertical direction can be further improved.

[0043] Furthermore, the bush 20 between the tangent line at the lowest point L (boundary 25) and the tangent line at the highest point H (boundary 27) is prone to moving together with the stabilizer bar 11 during vertical vibrations. Therefore, the shape of the bush 20 between them does not significantly contribute to the static spring constant of the bush 20 in the vertical direction.

[0044] On the other hand, the shape of the bush 20 outside the tangent lines (boundaries 25, 27) in the vertical direction tends to contribute to the vertical static spring constant of the bush 20. In this embodiment, the inclination of the lower base 24 and the upper base 26 starts from the tangent lines, boundaries 25, 27, respectively. That is, the lower base 24 and the upper base 26 are provided from the part that tends to contribute to improving the vertical static spring constant of the bush 20, and the part that contributes less can be made into a flat surface 23. As a result, a good balance can be achieved between reducing the volume of the bush 20 and improving the vertical static spring constant of the bush 20.

[0045] Below the stabilizer bar 11, the bush 20, compressed vertically between the stabilizer bar 11 and the bracket 12, expands mainly axially along the upper surface of the flat plate member 13. In contrast, above the stabilizer bar 11, the bush 20, compressed vertically between the stabilizer bar 11 and the bracket 12, expands not only axially but also perpendicular to the axis to conform closely to the uneven shape of the inner circumferential surface of the curved plate member 14.

[0046] Therefore, when the bush 20 is assembled from an unloaded state, the change in the amount of axial protrusion from the flat surface 23 is greater at the lower base 24 than at the upper base 26. However, in the unloaded state, the maximum axial protrusion from the flat surface 23 is set to be greater at a portion of the upper base 26 than at the lower base 24. Therefore, in the assembled state, the maximum protrusion can be made nearly identical at the lower base 24 and the upper base 26. As a result, the static spring constant in the downward direction and the static spring constant in the upward direction of the bush 20 can be brought closer to each other, resulting in a good balance of static spring constants in the vertical direction.

[0047] Next, a second embodiment will be described with reference to Figures 5(a) to 6. In the first embodiment, a bush 20 having a lower base 24 and an upper base 26 was described. In contrast, in the second embodiment, a bush 30 having a lower base 31 but no upper base 26 will be described. Note that parts identical to those in the first embodiment are denoted by the same reference numerals and their descriptions are omitted below.

[0048] Figure 5(a) is a front view of the bush 30 of the vibration isolation device in the second embodiment. Figure 5(b) is a bottom view of the bush 30 as seen in the direction of arrow Vb in Figure 5(a). Figure 6 is a cross-sectional view of the bush 30 along the line VI-VI in Figure 5(a).

[0049] The bush 30 is an elastic component that is assembled to the stabilizer bar 11 and the bracket 12 (see Figure 4). The bush 30 is formed in a cylindrical shape that surrounds the shaft C. The bush 30 has a through hole 21 into which the stabilizer bar 11 can be inserted, and an outer peripheral surface 22 into which the bracket 12 can make contact (tight contact).

[0050] The axial end face of the bush 30 is formed by a flat surface 23 perpendicular to the axis C and a lower base (first base) 31 that is inclined outward in the axial direction as it moves away from the through hole 21. In this embodiment, both axial end faces of the bush 30 are formed identically to each other.

[0051] The flat surfaces 23 are provided on both sides in the left-right direction and above the through hole 21. In other words, the area where the upper base 26 was formed in the first embodiment is the flat surface 23 in the second embodiment.

[0052] The lower base 31 is positioned downward (first direction) relative to the through hole 21. The lower base 31 is inclined outward in the axial direction as it extends downward, up to the curved surface 22b of the outer peripheral surface 22 of the bush 30. As a result, similar to the first embodiment, the lower base 31 can improve the static spring constant of the bush 30 against downward compressive deformation while suppressing an increase in the volume of the bush 30. Furthermore, the lower base 31 makes it more difficult for the bush 30 to slide axially relative to the bracket 12 when the bush 30 is compressed downward.

[0053] The boundary 32 between the flat surface 23 and the lower base 31 is formed in an arc shape, with the lowest point L on the inner periphery of the through hole 21 as its apex, and curving downward as it moves away from that apex in the left-right direction, in an axial view. More specifically, the boundary 32 is formed in an arc shape passing through the lowest point L and the lower right and lower left corners of the axial end face of the bush 30.

[0054] Here, the portion of the bush 30's shape that most easily contributes to improving the downward static spring constant is the part directly below the lowest point L, and its contribution decreases as it moves away from the lowest point L in the left-right direction. With the arc-shaped boundary 32 with the lowest point L as its apex, the lower base 31 can be provided over almost the entire portion that most easily contributes to improving the downward static spring constant of the bush 30, while increasing the proportion of the flat surface 23 as the contribution decreases. As a result, a good balance can be achieved between reducing the volume of the bush 30 and improving the downward static spring constant of the bush 30.

[0055] In the bottom view shown in Figure 5(b), the lower base 31 is curved such that the amount of axial overhang from the flat surface 23 gradually increases from both ends in the left-right direction towards the center (directly below the lowest point L). Therefore, the lower base 31 has a large axial overhang in the part that contributes most to improving the downward static spring constant of the bush 30, and the amount of axial overhang decreases as the contribution decreases. Thus, the balance between reducing the volume of the bush 30 and improving the downward static spring constant of the bush 30 can be further improved.

[0056] Next, a third embodiment will be described with reference to Figures 7 to 8(b). In the first embodiment, a bush 20 having a lower base 24 and an upper base 26 was described. In contrast, in the third embodiment, a bush 40 will be described in which a right base 41 and a left base 43 are provided on both sides in the left-right direction, instead of the lower base 24 and the upper base 26. Note that parts identical to those in the first embodiment are denoted by the same reference numerals and their descriptions will be omitted below.

[0057] Figure 7 is a front view of the bush 40 of the vibration isolation device in the third embodiment. Figure 8(a) is a cross-sectional view of the bush 40 along the line VIIIa-VIIIa in Figure 7. Figure 8(b) is a cross-sectional view of the bush 40 along the line VIIIb-VIIIb in Figure 7.

[0058] The bush 40 is an elastic component that is assembled to the stabilizer bar 11 and the bracket 12 (see Figure 4). The bush 40 is formed in a cylindrical shape that surrounds the shaft C. The bush 40 has a through hole 21 into which the stabilizer bar 11 can be inserted, and an outer peripheral surface 22 into which the bracket 12 can make contact (tight contact).

[0059] The axial end face of the bush 40 is formed by a flat surface 23 perpendicular to the axis C, and a right base (first base) 41 and a left base (second base) 43 that are inclined outward in the axial direction as they move away from the through hole 21. In this embodiment of the bush 40, both axial end faces are formed identically to each other. The flat surface 23 is provided on both sides in the vertical direction relative to the through hole 21.

[0060] The right base 41 is positioned to the right (first direction) of the through hole 21. The right base 41 is inclined outward in the axial direction as it moves to the right, up to the curved surface 22b of the outer peripheral surface 22 of the bush 40.

[0061] The left base 43 is positioned to the left (second direction) of the through hole 21. The left base 43 is inclined outward in the axial direction as it extends to the left, up to the curved surface 22b of the outer peripheral surface 22 of the bush 40.

[0062] These right and left bases 41 and 43 allow the bush 40 assembled to the stabilizer bar 11 and bracket 12 (see Figure 4) to achieve the same effects as in the first embodiment. Specifically, the right and left bases 41 and 43 make it difficult for the central part of the axial end face of the bush 40 to bulge on either side of the stabilizer bar 11 (through hole 21) during compression deformation in the left-right direction. Furthermore, the right and left bases 41 and 43 increase the contact area between the bush 40 and the bracket 12. As a result, the right and left bases 41 and 43 improve the static spring constant of the bush 40 against compression deformation in the left-right direction while suppressing an increase in the volume of the bush 40. In addition, the right and left bases 41 make it difficult for the bush 40 to slide axially relative to the bracket 12 when the bush 40 undergoes compression deformation in the left-right direction.

[0063] The shape of the bush 40 in the cross-section (Figure 8(a)) passing through the rightmost point S1 on the inner periphery of the through hole 21, the leftmost point S2 on the inner periphery of the through hole 21, and axis C is most likely to contribute to the static spring constant of the bush 40 in the left-right direction. Since a right base 41 and a left base 43 are provided in the left-right direction from these rightmost point S1 and leftmost point S2, respectively, the static spring constant of the bush 40 in the left-right direction can be further improved.

[0064] The boundary 42 between the flat surface 23 and the right base 41 is a straight line perpendicular to the left-right direction in an axial view, and is tangent to the rightmost point S1 of the through hole 21. The boundary 44 between the flat surface 23 and the left base 43 is a straight line perpendicular to the left-right direction in an axial view, and is tangent to the leftmost point S2 of the through hole 21. Furthermore, boundary 42 is the starting point of the inclination of the right base 41, and boundary 44 is the starting point of the inclination of the left base 43.

[0065] The bush 40 between the tangent line (boundary 42) at the rightmost point S1 and the tangent line (boundary 44) at the leftmost point S2 is prone to moving together with the stabilizer bar 11 during lateral vibrations. Therefore, the shape of the bush 40 between these points does not significantly contribute to the static spring constant of the bush 40 in the lateral direction. On the other hand, the shape of the bush 40 outside of these tangent lines (boundaries 42, 44) in the lateral direction is more likely to contribute to the static spring constant of the bush 40 in the lateral direction.

[0066] Therefore, in this embodiment, the right base 41 and the left base 43 are provided in the parts that are most likely to contribute to improving the static spring constant in the left-right direction of the bush 40, while the flat surface 23 is in the part that contributes less. As a result, a good balance can be achieved between reducing the volume of the bush 40 and improving the static spring constant in the left-right direction of the bush 40.

[0067] Furthermore, the right base 41 and the left base 43 are provided in the region that overlaps with the through hole 21 when viewed from the left to right. The portion that is separated from that region in the vertical direction (third direction) is formed by a flat surface 23. The areas on both sides of the right base 41 and the left base 43 in the vertical direction do not contribute much to improving the static spring constant of the bush 40 in the left to right direction. Therefore, by not providing the right base 41 and the left base 43 along the entire length in the vertical direction, a better balance can be achieved between reducing the volume of the bush 40 and improving the static spring constant of the bush 40 in the left to right direction.

[0068] The right base 41 and the left base 43 have the same vertical cross-sectional shape over almost their entire length in the vertical direction (except for the ends in the vertical direction). The vertical ends of the right base 41 and the left base 43 gradually decrease in axial projection from the flat surface 23 so that they smoothly connect with the flat surface 23. As a result, the bush 40 can be easily molded using a mold that splits in the center in the vertical direction.

[0069] Next, the fourth embodiment will be described with reference to Figures 9(a) to 10(b). In the first embodiment, a bush 20 having a lower base 24 and an upper base 26 was described. In contrast, in the fourth embodiment, a bush 50 having a lower base 51, an upper base 52, a right base 53 and a left base 54 will be described. Note that parts identical to those in the first and third embodiments are denoted by the same reference numerals and their descriptions are omitted below.

[0070] Figure 9(a) is a front view of the bush 50 of the vibration isolation device in the fourth embodiment. Figure 9(b) is a cross-sectional view of the bush 50 along the line IXb-IXb in Figure 9(a). Figure 10(a) is a cross-sectional view of the bush 50 along the line Xa-Xa in Figure 9(a). Figure 10(b) is a cross-sectional view of the bush 50 along the line Xb-Xb in Figure 9(a). In Figures 9(b) to 10(b), the case where the entire axial end face of the bush 50 is a flat surface 23 is shown by a dashed line.

[0071] The bush 50 is an elastic component that is assembled to the stabilizer bar 11 and the bracket 12 (see Figure 4). The bush 50 is formed in a cylindrical shape that surrounds the shaft C. The bush 50 has a through hole 21 into which the stabilizer bar 11 can be inserted, and an outer peripheral surface 22 into which the bracket 12 can make contact (tight contact).

[0072] The axial end faces of the bush 50 are formed by a flat surface 23 perpendicular to the axis C, and a lower base (first base) 51, an upper base (second base) 52, a right base 53, and a left base 54 that are inclined outward in the axial direction as they move away from the through hole 21. In this embodiment of the bush 50, both axial end faces are formed identically to each other. The flat surface 23 is provided on the upper right, upper left, lower right, and lower left sides around the through hole 21.

[0073] The lower base 51 is positioned in a downward direction (first direction) relative to the through hole 21. The lower base 51 is inclined outward in the axial direction as it extends downward to the curved surface 22b of the outer peripheral surface 22 of the bush 50. The upper base 52 is positioned in an upward direction (second direction) relative to the through hole 21. The upper base 52 is inclined outward in the axial direction as it extends upward to the curved surface 22b.

[0074] The right base 53 is positioned to the right of the through hole 21 (one of the third directions). The right base 53 is inclined outward in the axial direction as it extends to the right up to the curved surface 22b. The left base 54 is positioned to the left of the through hole 21 (the other of the third directions). The left base 54 is inclined outward in the axial direction as it extends to the left up to the curved surface 22b.

[0075] These bases 51-54, as in the first and third embodiments, allow for an improvement in the static spring constant of the bush 50 against compressive deformation in the vertical and horizontal directions, while suppressing an increase in the volume of the bush 50. Furthermore, the bases 51-54 make it more difficult for the bush 50 to slide axially relative to the bracket 12 when the bush 50 undergoes compressive deformation in the vertical or horizontal directions.

[0076] The starting point of the inclination of the right base 53, and the boundary 42 between the right base 53 and the flat surface 23, is the tangent to the rightmost point S1 of the through hole 21. The starting point of the inclination of the left base 54, and the boundary 44 between the left base 54 and the flat surface 23, is the tangent to the leftmost point S2 of the through hole 21. This allows for a good balance between reducing the volume of the bush 50 and improving the static spring constant of the bush 50 in the left-right direction, similar to the third embodiment.

[0077] The starting point of the inclination of the lower base 51 is formed by a curve 55a along the lower edge of the through hole 21 and straight lines 55b extending to the left and right from both ends of the curve 55a. The starting point of the inclination of the upper base 52 is formed by a curve 56a along the upper edge of the through hole 21 and straight lines 56b extending to the left and right from both ends of the curve 56a.

[0078] In this way, by combining curves 55a, 56a and straight lines 55b, 56b, the starting point of the inclination of the lower base 51 and upper base 52 can be brought closer to the through hole 21 overall. This makes it possible to further improve the static spring constant of the bush 50 against vertical compression deformation.

[0079] The lower base 51 is provided with a tilt adjustment section 51a near the curve 55a. The tilt adjustment section 51a is a part that makes it easier to align the amount of axial protrusion of the lower base 51 in the left-right direction between the lower side of the curve 55a and the lower side of the straight line 55b, without the lower edge of the through hole 21 protruding relative to the flat surface 23. For this reason, the tilt angle with respect to the flat surface 23 is greater at the tilt adjustment section 51a than at the lower base 51 other than the tilt adjustment section 51a.

[0080] This tilt adjustment section 51a prevents the lower edge of the through hole 21 from protruding relative to the flat surface 23, thereby reducing the volume of the bush 50. Furthermore, by aligning the axial protrusion of the lower base 51 other than the tilt adjustment section 51a with the left-right protrusion, the lower base 51 can be made easier to form.

[0081] Similarly, the upper base 52 is provided with a tilt adjustment section 52a near the curve 56a. The tilt angle with respect to the flat surface 23 is greater in the upper base 52a than in the upper base 52 other than the tilt adjustment section 52a. The tilt adjustment section 52a prevents the upper edge of the through hole 21 from protruding relative to the flat surface 23, thereby reducing the volume of the bush 50. Furthermore, by matching the axial protrusion of the upper base 52 other than the tilt adjustment section 52a in the left-right direction, the upper base 52 can be made easier to form.

[0082] Each base plate 51-54 is connected to the others in the circumferential direction. The boundary M between each base plate 51-54 is located on a cross section (for example, the cross section in Figure 10(b)) that passes through the axis C and the lower right or lower left corner of the bush 50.

[0083] The axial end faces of the bushes 50 on both sides of boundary M are inclined outward in the axial direction as they extend toward the curved surface 22b, by the respective bases 51-54, in the direction in which boundary M extends (hereinafter referred to as the "boundary M direction").

[0084] The portion that slopes toward the boundary M direction (hereinafter referred to as the "boundary M base") has its starting point of inclination away from the through hole 21. Since the starting point of this inclination is located closer to the through hole 21 than half of the shortest distance in the boundary M direction from the through hole 21 to the curved surface 22b, similar to the bases 51 to 54, it is possible to improve the static spring constant of the bush 50 against compressive deformation in the boundary M direction while suppressing an increase in the volume of the bush 50.

[0085] Although the present invention has been described above based on embodiments, it can be easily inferred that the present invention is not limited in any way to the above embodiments, and that various improvements and modifications are possible without departing from the spirit of the present invention. For example, the shape of the outer peripheral surface 22 in the axial view may be circular or polygonal. Also, the concave surface 22a of the outer peripheral surface 22 may be omitted.

[0086] In the above embodiment, the case in which bushes 20, 30, 40, and 50 are stabilizer bushes that are compressed perpendicular to the axis between the stabilizer bar 11 and the bracket 12 has been described, but the present invention is not necessarily limited to this. For example, the present invention may be applied to a cylindrical bush made of an elastic material that is compressed perpendicular to the axis between a axial first member attached to the vibration source side such as an engine or motor and a cylindrical second member attached to the vibration receiving side such as a vehicle body. In addition, the first member may be attached to the vibration receiving side and the second member may be attached to the vibration source side. The shape of the through hole 21 and the outer circumferential surface 22 may be appropriately changed to match the shape of the first member and the second member.

[0087] In the above embodiment, for example, a case was described in which the lower base 24, located below the through hole 21, is inclined outward in the axial direction as it moves downward, but it is not necessarily limited to this. The first base, located in a first direction perpendicular to the axis with respect to the through hole 21, is sufficient if it is inclined outward in the axial direction as it moves toward that first direction, and this first direction is not limited to downward. For example, the first direction may be upward, to the right, or to the left, perpendicular to the axis, or it may be an oblique direction to the up, down, left, or right. If the upward direction is the first direction, the upper base 26 becomes the first base.

[0088] Furthermore, a second base may be provided at a position in a second direction opposite to the first direction relative to the through hole 21, and which inclins outward in the axial direction as it approaches the second direction. For example, if the lower base 24 is the first base, the second direction will be upward, and the upper base 26 will be the second base. Alternatively, a base may be provided in a direction perpendicular to the axis relative to the through hole 21, but different from the first and second directions. Examples of such directions include a third direction perpendicular to the first direction, and a direction inclined at 45° from the first direction.

[0089] In the above embodiment, the starting points of the inclination of the lower bases 24, 31, 51, the upper bases 26, 52, the right base 41, 53, and the left base 43, 54 (boundaries 25, 27, 32, 42, 44, curves 55a, 56a, and straight lines 55b, 56b) are described as being in contact with the inner periphery of the through hole 21, but this is not necessarily the only case. The starting points of these inclinations may also be shifted parallel to the direction perpendicular to the axis.

[0090] For example, when the first base is provided at a position away from the through hole 21 in the first direction, it is preferable that the starting point of the inclination of the first base is located closer to the through hole 21 than half of the shortest distance in the first direction from the through hole 21 to the outer peripheral surface 22. In this case, the static spring constant of the bush in the first direction can be sufficiently improved by the first base.

[0091] Furthermore, the shape of the starting point of the inclination of each base in the axial view may be changed as appropriate. Examples of such shapes include one or more straight lines, one or more curves, and a combination of straight lines and curves. However, if the starting point of the inclination of the base is only a straight line, and especially only a single straight line, the base can be manufactured more easily.

[0092] In the above embodiment, for example, the case in which the cross-sectional shape of the lower base 24 and the upper base 26 is the same over the entire length in the left-right direction (third direction) was described, but it is not necessarily limited to this. For example, the lower base 24 and the upper base 26 may be bulged in the axial direction at the center in the left-right direction, as in the second embodiment, or they may be recessed in the axial direction at the center in the left-right direction. The same applies to each base other than the lower base 24 and the upper base 26.

[0093] In the above embodiment, the case in which both axial end faces of bushes 20, 30, 40, and 50 are formed identically was described, but these end faces may be different. For example, one axial end face of bushes 20, 30, 40, and 50 may be made only a flat surface. Alternatively, one axial end face of a bush may be made identical to that of one of the above embodiments, while the other axial end face of the bush may be made identical to that of another above embodiment. [Explanation of Symbols]

[0094] 10 Vibration Isolator 11. Stabilizer bar (first component) 12 Bracket (second component) 20, 30, 40, 50 bush 21 Through hole 22 Outer surface 23 Flat surface 24, 31, 51 Lower pedestal (first pedestal) 25,27,32,42,44 boundary 26,52 Upper pedestal (second pedestal) 41, 53 Right pedestal (first pedestal) 43, 54 Left pedestal (second pedestal) C-axis

Claims

1. A vibration isolation device comprising an elastic body that is compressed perpendicular to the axis between the outer circumferential surface of a shaft-shaped first member and the inner circumferential surface of a cylindrical second member, and a cylindrical bush surrounding the axis, The bush has a through hole into which the first member can be inserted and which forms the inner circumferential surface of the bush, The bush comprises a first base formed on at least one end face in the axial direction of the bush at a position in a first direction perpendicular to the axis of the through hole, The vibration isolation device is characterized in that the first base is inclined outward in the axial direction as it approaches the first direction, up to the outer circumferential surface of the bush that can contact the second member.

2. The vibration isolation device according to claim 1, characterized in that the first base is formed on both axial end faces of the bush.

3. The bush comprises a second base formed on at least one end face in the axial direction of the bush in a position opposite to the first direction with respect to the through hole, The vibration isolation device according to claim 1, characterized in that the second base is inclined outward in the axial direction as it approaches the second direction, up to the outer circumferential surface of the bush that can contact the second member.

4. The vibration isolation device according to claim 1, characterized in that the first base is formed on the axial end face of the bush over its entire length in the axial direction and in a third direction perpendicular to the first direction.

5. The vibration isolation device according to claim 1, characterized in that the first base has the same cross-sectional shape over its entire length in the axial direction and in a third direction perpendicular to the first direction.

6. The axial end face of the bush has a flat surface perpendicular to the axis, The vibration isolation device according to claim 1, characterized in that the boundary between the flat surface and the first base is a straight line perpendicular to the first direction in an axial view and tangent to the inner peripheral edge of the through hole.

7. The vibration isolation device according to any one of claims 1 to 6, further comprising the second member that contacts the outer circumferential surface of the bush without adhesive.

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