Bumper cap and buffering device

Abstract

To provide a bumper cap and the like capable of suppressing abnormal noise caused by contact with a stopper rubber.SOLUTION: A bumper cap includes: an annular part where a through hole going through a rod protruding from a cylinder part is formed and which is disposed on one side in an axial direction of the rod more than the cylinder part; and a cylindrical part which protrudes to the other side in the axial direction from an outer peripheral part in the annular part and covers the outer peripheral surface in the cylinder part. The annular part has a plurality of projections on the other side protruding to the other side and forms a guideway guiding to the cylindrical part fluid flown through the through hole between the adjacent other side projections. The cylindrical part has a plurality of inside projections protruding inward, forms a discharge passage discharging the fluid guided in the guideway between the adjacent inside projections outside, and further has a diaphragm which is provided in the guideway and narrows a flow passage area of the fluid flown in through the through hole.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present invention relates to a bumper cap and a shock absorber.

Background Art

[0002] Conventionally, techniques for suppressing the generation of abnormal noises in shock absorbers have been proposed. For example, a bumper cap attached to a shock absorber body described in Patent Document 1 has an opening at one end and a bottom portion and a through hole penetrating the bottom portion at the other end, and a cover portion covering the shock absorber body, and a plurality of protruding portions protruding from the bottom portion of the cover portion toward the opening side and having a gap formed between adjacent ones. And the bumper cap described in Patent Document 1 includes a suppressing portion that suppresses the rotation in the cover portion of the fluid that flows from outside the cover portion through the through hole and flows between the inside of the cover portion and the shock absorber body.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] According to the bumper cap described in Patent Document 1, for example, in the compression stroke of the shock absorber, the amount of the cylinder entering the dust cover increases, so the flow rate of the air in the dust cover pushed out by the cylinder is large, and it is possible to prevent abnormal noises caused by the wind noise generated when the flow velocity is high. However, in the bumper cap described in Patent Document 1, there is room for improvement in suppressing abnormal noises caused by a small flow rate and contact between the bumper cap and the stopper rubber. An object of the present invention is to provide a bumper cap or the like that can suppress abnormal noises caused by contact with a stopper rubber.

Means for Solving the Problem

[0005] The present invention completed for such an object has a through-hole through which a rod protruding from a cylinder portion passes, and an annular portion disposed on one side in the axial direction of the rod with respect to the cylinder portion, and an outer peripheral portion of the annular portion protrudes to the other side in the axial direction and covers an outer peripheral surface of the cylinder portion. The annular portion has a plurality of convex portions on the other side protruding to the other side, and forms a guide path for guiding the fluid flowing in from the through-hole between adjacent convex portions on the other side to the cylindrical portion. The cylindrical portion has a plurality of convex portions protruding inward, and forms a discharge path for discharging the fluid guided by the guide path between adjacent convex portions to the outside. The bumper cap further has a throttle portion provided in the guide path for narrowing the flow passage area of the fluid flowing in from the through-hole.

Advantages of the Invention

[0006] According to the present invention, it is possible to provide a bumper cap or the like that can suppress abnormal noise caused by contact with a stopper rubber.

Brief Description of the Drawings

[0007]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Figure 12

Figure 13

Figure 14

[0008] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. <First Embodiment> FIG. 1 is a view showing an example of a schematic configuration of a suspension device 1 according to the first embodiment. FIG. 2 is an example of an enlarged view of part II of FIG. 1. FIG. 3 is a view showing an example of a view of the bumper cap 100 as seen from the first side in the axial direction. FIG. 4 is an example of a perspective view of the bumper cap 100 as seen from the first side. The suspension device 1 is a suspension used for a four-wheeled vehicle such as a passenger car. As shown in FIG. 1, it includes a hydraulic shock absorber 2 and a coil spring 3 disposed outside the shock absorber 2. Further, the suspension device 1 includes a lower spring seat 4 that supports an end portion of the coil spring 3 on the first side (the lower side in FIG. 1) in the axial direction of a rod 20 described later, and an upper spring seat 5 that supports an end portion of the coil spring 3 on the second side (the upper side in FIG. 1) in the axial direction of the rod 20.

[0009] Moreover, the suspension device 1 includes a vehicle body side bracket 6 for attaching the suspension device 1 to the vehicle, a wheel side bracket 7 for attaching the suspension device 1 to the wheel, a dust cover 8 that covers at least a part of the cylinder portion 10 and the rod 20, and a stopper rubber 9. The stopper rubber 9 is a cylindrical rubber member. Hereinafter, the axial direction of the rod 20 may be simply referred to as the "axial direction". Also, the first side (the lower side in FIG. 1) and the second side (the upper side in FIG. 1) in the axial direction may be simply referred to as the "first side" and the "second side", respectively. Further, the direction intersecting the axial direction (for example, the orthogonal direction) is referred to as the "radial direction". In the radial direction, the side closer to the center line of the cylinder 11 may be simply referred to as the "inner side", and the side away from the center line may be simply referred to as the "outer side".

[0010] Hereinafter, the shock absorber 2 will be described in detail. The shock absorber 2 includes a cylinder portion 10 that houses oil, and a rod 20 whose end portion on the second side protrudes from the cylinder portion 10 and whose end portion on the first side is inserted into the cylinder portion 10. Further, the shock absorber 2 includes a piston portion 30 provided at the end portion on the first side of the rod 20, and a bottom portion 40 provided at the end portion on the first side of the cylinder portion 10. Moreover, the shock absorber 2 includes a bumper cap 100 that is press-fitted into the end portion on the second side of the cylinder portion 10 and regulates the maximum compression stroke by receiving the load of the stopper rubber 9 generated during compression.

[0011] The rod 20 is a rod-shaped member that extends longitudinally in the axial direction. The rod 20 holds the piston portion 30 on the first side. Also, the rod 20 is connected to, for example, the vehicle body via the vehicle body side bracket 6 on the second side.

[0012] The cylinder portion 10 has a cylinder 11 that houses oil and an outer cylinder body 12 provided outside the cylinder 11. A reservoir chamber R is formed between the cylinder 11 and the outer cylinder body 12. The space inside the cylinder 11 is partitioned by the piston portion 30 into a first oil chamber Y1 and a second oil chamber Y2. The reservoir chamber R is partitioned from the first oil chamber Y1 by the bottom portion 40.

[0013] Further, the cylinder portion 10 includes a rod guide portion 15 that movably supports the rod 20 and an oil seal 80 that prevents oil leakage inside the cylinder portion 10 and entry of foreign matter into the cylinder portion 10.

[0014] As shown in FIG. 2, the oil seal 80 has an annular ring 81 formed of a metal such as steel and an elastic portion 90 formed of a material having a low elastic modulus such as synthetic rubber. The oil seal 80 is formed by, for example, baking and adhering the elastic portion 90 to the ring 81, and the ring 81 holds the elastic portion 90. The ring 81 is annular, has an inner diameter larger than the outer diameter of the rod 20, and an outer diameter smaller than the inner diameter of the end portion on the second side of the outer cylinder body 12.

[0015] The elastic portion 90 is provided on the first side of the ring 81, has a wedge-shaped cross-sectional shape, and has a seal lip portion 91 that is pressed by an annular spring and is in close contact with the entire outer peripheral surface of the rod 20. Also, the elastic portion 90 is provided on the second side of the ring 81 and has a dust lip 92 that suppresses entry of dust from the outside by being in close contact with the entire outer peripheral surface of the rod 20. The seal lip portion 91 and the dust lip 92 are integrally formed so as to be joined at a portion inside the ring 81.

[0016] The cylinder portion 10 and the rod 20 configured as described above are assembled as follows. That is, a cylinder 11 with a bottom portion 40 press-fitted inside is inserted into the outer cylinder 12 of the cylinder portion 10. Then, a rod 20 that holds a piston portion 30 at the end on the first side is inserted into the cylinder 11 from the side of the piston portion 30. Then, a rod guide portion 15 and an oil seal 80 are inserted into the outer cylinder 12, and a so-called roll caulking is performed by bending the end on the second side of the outer cylinder 12 inward, thereby fixing the rod guide portion 15 and the oil seal 80 between the cylinder 11 and the caulked portion 13 of the outer cylinder 12.

[0017] (Bumper cap 100) Hereinafter, the bumper cap 100 will be described in detail with reference to FIGS. 2 to 4. The bumper cap 100 is disposed on the second side of the outer cylinder 12 of the cylinder portion 10 and includes an annular portion 110 having an annular shape with a through hole 111 formed in the central portion for passing the rod 20. Further, the bumper cap 100 includes a cylindrical portion 120 that protrudes axially from the outer peripheral portion of the annular portion 110 to the first side and covers the outer peripheral surface of the outer cylinder 12, and a protruding portion 130 that protrudes outward from the end on the first side of the cylindrical portion 120. Further, the bumper cap 100 further includes a throttle portion 140 provided in a guide path 150 described later for reducing the flow path area of air (an example of a fluid) flowing in from the through hole 111. It can be exemplified that the bumper cap 100 is integrally formed of resin.

[0018] The annular portion 110 is a thin plate-like portion whose axial size is smaller than its radial size, and the second surface 112, which is the surface on the second side, is flat. The annular portion 110 has a first-side convex portion 114 that protrudes to the first side from the first surface 113, which is the surface on the first side. A plurality (six in FIG. 3) of the first-side convex portions 114 are provided in the circumferential direction. The first-side convex portion 114 extends from the central portion of the annular portion 110 to the cylindrical portion 120 in the radial direction and is provided over an angular range of 35 degrees in the circumferential direction.

[0019] The cylindrical portion 120 has an inner convex portion 122 that protrudes inward from the inner peripheral surface 121, which is the inner surface. A plurality (six in FIG. 4) of inner convex portions 122 are provided in the circumferential direction. In other words, the number of inner convex portions 122 provided is the same as that of the first side convex portions 114, and each inner convex portion 122 is provided at a position in the circumferential direction where the first side convex portion 114 is provided. In the present embodiment, the circumferential size of each inner convex portion 122 is smaller than the circumferential size of the first side convex portion 114 and is provided over an angular range of 10 degrees.

[0020] The inner surface 123 of the inner convex portion 122 is formed in an arc shape when viewed in the axial direction. When the inner surfaces 123 of the plurality of inner convex portions 122 are virtually connected, a circle is formed, and the diameter of the circle is smaller than the outer diameter of the outer cylinder 12 of the cylinder portion 10. The inner convex portion 122 is provided at the central portion of the cylindrical portion 120 in the axial direction, and the axial size is 1 / 2 of the axial size of the cylindrical portion 120.

[0021] The protruding portion 130 is a thin plate-like portion whose axial size is smaller than its radial size. A plurality (three in FIG. 3) of protruding portions 130 are provided in the circumferential direction. The protruding portion 130 is provided over an angular range of 60 degrees in the circumferential direction.

[0022] The bumper cap 100 configured as described above is fitted into the second side end of the outer cylinder 12 of the cylinder portion 10 from the first side opening of the cylindrical portion 120 and is press-fitted into the cylinder portion 10 until the first side surface of the first side convex portion 114 of the annular portion 110 contacts the caulking portion 13 of the cylinder portion 10. As described above, since the diameter of the virtual circle formed by the inner surfaces 123 of the plurality of inner convex portions 122 of the cylindrical portion 120 is smaller than the outer diameter of the outer cylinder 12, the inner surfaces 123 of the plurality of inner convex portions 122 are press-fitted so as to contact the outer peripheral surface of the outer cylinder 12. Then, the first side end of the dust cover 8 is hooked on the protruding portion 130 of the bumper cap 100, and the dust cover 8 is held by the bumper cap 100.

[0023] In a state where the bumper cap 100 is press-fitted into the outer cylinder 12, the dust lip 92 of the oil seal 80 is positioned inside the through-hole 111 of the annular portion 110. Therefore, when the suspension device 1 is compressed, the amount of entry of the cylinder portion 10 into the dust cover 8 increases, so that the air in the dust cover 8 pushed out by the cylinder portion 10 flows in from the through-hole 111, passes outside the dust lip 92, and reaches the gap between the first surface 113 of the annular portion 110 and the ring 81 of the oil seal 80.

[0024] And the bumper cap 100 forms a guide path 150 for guiding the air flowing in from the through-hole 111 to the cylindrical portion 120 between adjacent first side convex portions 114. That is, six guide paths 150 are formed around the dust lip 92 of the oil seal 80 between the annular portion 110 of the bumper cap 100 and the end portion on the second side in the cylinder portion 10.

[0025] Further, the bumper cap 100 forms a discharge path 160 for discharging the air guided by the guide path 150 to the outside in the gap between the inner peripheral surface 121 of the cylindrical portion 120 and the outer peripheral surface of the outer cylinder 12. In the axial direction, in the portion where the inner convex portion 122 is provided on the cylindrical portion 120, the space between adjacent inner convex portions 122 serves as the discharge path 160. That is, according to the bumper cap 100 configured as described above, the air flowing in from the through-hole 111 is discharged to the outside through the guide path 150 and the discharge path 160.

[0026] Next, the throttle portion 140 will be described in detail. In the following description, when viewed axially from the first side as shown in FIG. 3, the clockwise direction in the circumferential direction may be referred to as the "first direction", and the counterclockwise direction may be referred to as the "second direction". The throttle portion 140 has a first direction portion 141 extending in the first direction from a third surface 115 which is an end surface in the first direction rather than the circumferential center portion of the first side convex portion 114, and a second direction portion 142 extending in the second direction from a fourth surface 116 which is an end surface in the second direction rather than the circumferential center portion of the first side convex portion 114.

[0027] The first direction portion 141 and the second direction portion 142 are provided such that the protruding amount from the first surface 113 to the first side is the same as that of the first side convex portion 114. In the radial direction, the first direction portion 141 is provided outside the second direction portion 142. In the circumferential direction, the first direction portion 141 and the second direction portion 142 partially overlap, and a circumferential gap 151, which is the gap between the first direction portion 141 and the second direction portion 142, is formed.

[0028] FIG. 5 is a diagram showing an example of the air flow in the throttle portion 140. In the throttle portion 140 configured as described above, as shown in FIG. 5, the air that has flowed into the guide path 150 flows into the circumferential gap 151 through the third side gap 143, which is the gap between the third surface 115 of the first side convex portion 114 and the tip of the second direction portion 142. Then, the air that has passed through the circumferential gap 151 flows out of the circumferential gap 151 through the fourth side gap 144, which is the gap between the fourth surface 116 of the first side convex portion 114 and the tip of the first direction portion 141. By passing through the throttle portion 140, the flow path area of the air passing through the guide path 150 is narrowed.

[0029] As described above, the bumper cap 100 is formed with a through hole 111 through which the rod 20 protruding from the cylinder portion 10 passes, and includes an annular portion 110 (an example of an annular portion) disposed on the second side (an example of one side) in the axial direction of the rod 20 with respect to the cylinder portion 10. Further, the bumper cap 100 includes a cylindrical portion 120 (an example of a cylindrical portion) that protrudes from the outer peripheral portion of the annular portion 110 to the first side (an example of the other side) and covers the outer peripheral surface of the cylinder portion 10. The annular portion 110 has a plurality of first side convex portions 114 (an example of the other side convex portions) protruding to the first side, and forms a guide path 150 that guides the air flowing in from the through hole 111 between the adjacent first side convex portions 114 to the cylindrical portion 120. The cylindrical portion 120 has a plurality of inner convex portions 122 protruding inward, and forms a discharge path 160 that discharges the air guided by the guide path 150 between the adjacent inner convex portions 122 to the outside. And the bumper cap 100 further has a throttle portion 140 provided in the guide path 150 for restricting the flow passage area of the air flowing in from the through hole 111.

[0030] In the bumper cap 100 configured as described above, when the suspension device 1 compresses, the stopper rubber 9 contacts the second surface 112 of the annular portion 110. Then, since the air generated due to the contact of the stopper rubber 9 with the second surface 112 of the annular portion 110 is throttled at the throttle portion 140, abnormal noise caused by the contact between the stopper rubber 9 and the bumper cap 100 is suppressed. Further, in the guide path 150, the throttle portion 140 has a labyrinth structure such that the third side gap 143 is formed on the third surface 115 side of the first side convex portion 114 and the fourth side gap 144 is formed on the fourth surface 116 side of the first side convex portion 114. Therefore, when the suspension device 1 extends, the bumper cap 100 can suppress dust from flowing into the dust lip 92 of the oil seal 80 or into the dust cover 8 even if dust is mixed in the air sucked into the dust cover 8 due to a decrease in the amount of the cylinder portion 10 entering the dust cover 8. Also, by changing the sizes and lengths of the third side gap 143, the fourth side gap 144, and the circumferential gap 151 in the throttle portion 140 according to the frequency of the abnormal noise generated due to the contact of the stopper rubber 9 with the second surface 112 of the annular portion 110, abnormal noises of various suspension devices 1 can be suppressed.

[0031] Here, the throttle portion 140 has a circumferential gap 151 as an example of a flow path extending in the circumferential direction. Thereby, since the air generated due to the contact of the stopper rubber 9 with the bumper cap 100 is accurately throttled, abnormal noise caused by the contact between the stopper rubber 9 and the bumper cap 100 is accurately suppressed.

[0032] In the bumper cap 100, the number of the first side convex portions 114 and the angular range (for example, 35 degrees) in which the first side convex portions 114 are provided are not particularly limited. Similarly, the number of the inner convex portions 122 and the angular range (for example, 10 degrees) in which the inner convex portions 122 are provided are not particularly limited.

[0033] (Modification example of the throttle portion 140) The shape of the throttle portion 140 that restricts the flow path area of the air flowing in from the through hole 111 in the bumper cap 100 is not particularly limited. Hereinafter, modified examples of the throttle portion 140 will be described. Hereinafter, differences from the throttle portion 140 will be described. The same components in the throttle portion 140 and the modified examples are denoted by the same reference numerals, and detailed descriptions thereof are omitted.

[0034] FIG. 6 is a view showing an example of a view of the throttle portion 170 according to the first modified example as seen from the first side in the axial direction. The throttle portion 170 according to the first modified example has a first direction portion 171 and a second direction portion 172 corresponding to the first direction portion 141 and the second direction portion 142, respectively. The first direction portion 171 extends in a direction inclined with respect to the first direction from the third surface 115 of the first side convex portion 114, and the second direction portion 172 extends in a direction inclined with respect to the second direction from the fourth surface 116 of the first side convex portion 114. Also in the throttle portion 170, since the flow path area of the air flowing into the guide path 150 is restricted, abnormal noise caused by the air generated due to the stopper rubber 9 (see FIG. 1) contacting the second surface 112 (see FIG. 2) of the annular portion 110 is suppressed.

[0035] FIG. 7 is a view showing an example of a view of the throttle portion 180 according to the second modified example as seen from the first side in the axial direction. The throttle portion 180 according to the second modified example has a first direction portion 181 and a second direction portion 182 corresponding to the first direction portion 141 and the second direction portion 142, respectively. The first direction portion 181 has an inner protruding portion 183 protruding inward from the tip, and the second direction portion 182 has an outer protruding portion 184 protruding outward from the tip.

[0036] In the throttle portion 180, the air that has flowed into the guide path 150 through the through-hole 111 flows into the circumferential gap 151 through the gap between the third surface 115 of the first side convex portion 114 and the outer protruding portion 184 of the second direction portion 182. After flowing inward by the inner protruding portion 183 of the first direction portion 181, it flows outward through the gap between the fourth surface 116 of the first side convex portion 114 and the inner protruding portion 183 of the first direction portion 181. In other words, the throttle portion 180 has a circumferential gap 151 as an example of a flow path extending in the circumferential direction, and gaps between the third surface 115 and the outer protruding portion 184 and between the fourth surface 116 and the inner protruding portion 183 as examples of flow paths extending in a direction intersecting the circumferential direction. As a result, it becomes difficult for the air flowing in from the through-hole 111 to be discharged to the outside through the discharge path 160 (see FIG. 2), so that the abnormal noise caused by the air generated due to the contact of the stopper rubber 9 (see FIG. 1) with the second surface 112 (see FIG. 2) of the annular portion 110 is suppressed.

[0037] FIG. 8 is a view showing an example of a view of the throttle portion 190 according to the third modification as seen from the first side in the axial direction. The throttle portion 190 according to the third modification is different from the throttle portion 140 in that neither the first direction portion 141 nor the second direction portion 142 is provided. FIG. 8 shows the throttle portion 190 in a mode in which the first direction portion 141 is not provided. In the throttle portion 190, the air that has flowed into the guide path 150 through the through-hole 111 flows out to the discharge path 160 (see FIG. 2) through the third side gap 143, which is the gap between the third surface 115 of the first side convex portion 114 and the tip of the second direction portion 142. And by passing through the throttle portion 190, the flow cross-sectional area of the air passing through the guide path 150 is reduced. As a result, the abnormal noise caused by the air generated due to the contact of the stopper rubber 9 (see FIG. 1) with the second surface 112 (see FIG. 2) of the annular portion 110 is suppressed.

[0038] <Second Embodiment> FIG. 9 is a view showing an example of a view of the bumper cap 200 according to the second embodiment as seen from the first side in the axial direction. The bumper cap 200 according to the second embodiment is different from the bumper cap 100 according to the first embodiment in that the throttle portion 240 corresponding to the throttle portion 140 is different. Hereinafter, the differences from the first embodiment will be described. The same components in the first and second embodiments are denoted by the same reference numerals, and their detailed descriptions are omitted.

[0039] The throttle portion 240 has a first direction portion 241 extending in the first direction from the third surface 115 of the first side convex portion 114 and a second direction portion 242 extending in the second direction from the fourth surface 116 of the first side convex portion 114. The radial position of the first direction portion 241 is the same as the radial position of the second direction portion 242, and a central gap 255 is formed between the tip of the first direction portion 241 and the tip of the second direction portion 242.

[0040] Further, the throttle portion 240 is provided with a circumferential direction portion 243 extending in the circumferential direction at a position where the radial position is outside the first direction portion 241 and the second direction portion 242 and the circumferential position is the same as that of the central gap 255. The circumferential direction portion 243 is provided so as to form a third side gap 253 between the third surface 115 of the first side convex portion 114 and a fourth side gap 254 between the fourth surface 116.

[0041] The first direction portion 241, the second direction portion 242, and the circumferential direction portion 243 are provided so that the amount of protrusion from the first surface 113 to the first side (see FIG. 2) is the same as that of the first side convex portion 114. Therefore, in the throttle portion 240, the air flowing into the guide path 150 through the through hole 111 heads toward the discharge path 160 (see FIG. 2) through the central gap 255. The air passing through the central gap 255 collides with the circumferential direction portion 243 and branches into air flowing in the first direction and air flowing in the second direction along the circumferential direction portion 243. Then, the air flowing in the first direction along the circumferential direction portion 243 flows out to the discharge path 160 through the fourth side gap 254, and the air flowing in the second direction along the circumferential direction portion 243 flows out to the discharge path 160 through the third side gap 253.

[0042] In the bumper cap 200 configured as described above, since the air generated due to the stopper rubber 9 (see FIG. 1) contacting the second surface 112 (see FIG. 2) of the annular portion 110 is throttled by the throttle portion 240, abnormal noise caused by the contact between the stopper rubber 9 and the bumper cap 200 is suppressed. Further, when the suspension device 1 extends, even if dust is mixed in the air sucked into the dust cover 8 (see FIG. 1) due to a decrease in the amount of entry of the cylinder portion 10 (see FIG. 1) into the dust cover 8, the dust cannot reach the dust lip 92 (see FIG. 2) of the oil seal 80 (see FIG. 2) without passing through the central gap 255 after passing through the third side gap 253 or the fourth side gap 254. Therefore, the bumper cap 200 can suppress dust from flowing into the dust lip 92 of the oil seal 80 and the dust cover 8. Further, by changing the sizes and lengths of the central gap 255, the third side gap 253, and the fourth side gap 254 in the throttle portion 240 in accordance with the frequency of abnormal noise generated due to the stopper rubber 9 contacting the second surface 112 of the annular portion 110, abnormal noise of various suspension devices 1 can be suppressed.

[0043] In the throttle portion 240 according to the second embodiment, after the air that has flowed into the guide passage 150 through the through hole 111 passes through the central gap 255 which is a single gap, it flows out into the discharge passage 160 (see FIG. 2) through the third side gap 253 and the fourth side gap 254 which are two gaps. In other words, the throttle portion 240 includes the central gap 255 as an example of a primary throttle portion that narrows the flow passage area of the air flowing in from the through hole 111, and the circumferential gap 251 between the first direction portion 241 or the second direction portion 242 and the circumferential direction portion 243 as an example of an expansion portion that expands the flow passage area of the air that has passed through the central gap 255. Further, the throttle portion 240 has the third side gap 253 and the fourth side gap 254 as an example of a secondary throttle portion that narrows the flow passage area of the air that has passed through the circumferential gap 251. Furthermore, in other words, after the air that has flowed into the guide passage 150 passes through a single gap (central gap 255) provided on the upstream side, it flows out into the discharge passage 160 through two gaps (third side gap 253 and fourth side gap 254) provided on the downstream side. However, the number of gaps provided on the upstream side and the number of gaps provided on the downstream side are not limited to 1 and 2, respectively.

[0044] FIG. 10 is a view showing an example of a view of a modified example of the throttle portion 240 according to the second embodiment as seen from the first side in the axial direction. As shown in FIG. 10, for example, in a modified example of the throttle portion 240, the air that has flowed into the guide passage 150 through the through hole 111 may pass through two gaps 261 provided on the upstream side and then flow out into the discharge passage 160 (see FIG. 2) through three gaps 262 provided on the downstream side.

[0045] <Third Embodiment> FIG. 11 is a view showing an example of a view of the bumper cap 300 according to the third embodiment as seen from the first side in the axial direction. The bumper cap 300 according to the third embodiment is different from the bumper cap 100 according to the first embodiment in that the throttle portion 340 corresponding to the throttle portion 140 is different. Hereinafter, the differences from the first embodiment will be described. The same components in the first embodiment and the third embodiment are denoted by the same reference numerals, and the detailed description thereof will be omitted.

[0046] The throttle portion 340 has a first-direction portion 341 extending in the first direction from the third surface 115 of the first side convex portion 114, and a second-direction portion 342 extending in the second direction from the fourth surface 116 of the first side convex portion 114. The radial position in the first-direction portion 341 and the radial position in the second-direction portion 342 are the same, and a central gap 355 is formed between the tip of the first-direction portion 341 and the tip of the second-direction portion 342.

[0047] Further, the throttle portion 340 is provided with a circumferential-direction portion 343 extending in the circumferential direction at a position where the radial position is inside the first-direction portion 341 and the second-direction portion 342 and the circumferential position is the same as that of the central gap 355. The circumferential-direction portion 343 is provided so as to form a third-side gap 353 between it and the third surface 115 of the first side convex portion 114 and to form a fourth-side gap 354 between it and the fourth surface 116.

[0048] The first-direction portion 341, the second-direction portion 342, and the circumferential-direction portion 343 are provided such that the amount of protrusion from the first surface 113 to the first side (see FIG. 2) is the same as that of the first side convex portion 114. Therefore, in the throttle portion 340, the air that has flowed into the guide path 150 through the through hole 111 heads toward the discharge path 160 (see FIG. 2) through the third-side gap 353 or the fourth-side gap 354. The air that has passed through the third-side gap 353 travels in the first direction along the first-direction portion 341, merges with the air that has passed through the fourth-side gap 354 and travels in the second direction along the second-direction portion 342, and flows out into the discharge path 160 through the central gap 355.

[0049] In the bumper cap 300 configured as described above, since the air generated due to the stopper rubber 9 (see FIG. 1) contacting the second surface 112 (see FIG. 2) of the annular portion 110 is throttled by the throttle portion 340, abnormal noise caused by the contact between the stopper rubber 9 and the bumper cap 300 is suppressed. Further, when the suspension device 1 extends, even if dust is mixed in the air sucked into the dust cover 8 because the amount of entry of the cylinder portion 10 (see FIG. 1) into the dust cover 8 decreases, the dust cannot reach the dust lip 92 (see FIG. 2) of the oil seal 80 unless it passes through the third side gap 353 or the fourth side gap 354 after passing through the central gap 355. Therefore, the bumper cap 300 can suppress dust from flowing into the dust lip 92 of the oil seal 80 and into the dust cover 8. Also, by changing the sizes and lengths of the central gap 355, the third side gap 353, and the fourth side gap 354 in the throttle portion 340 according to the frequency of abnormal noise generated due to the stopper rubber 9 contacting the second surface 112 of the annular portion 110, abnormal noise of various suspension devices 1 can be suppressed.

[0050] Here, the throttle portion 340 has the third side gap 353 and the fourth side gap 354 as an example of a branch portion for branching the air flowing in from the through hole 111, and the central gap 355 as an example of a confluence portion for confluencing the air branched at the third side gap 353 and the fourth side gap 354. Thereby, since the air generated due to the stopper rubber 9 (see FIG. 1) contacting the bumper cap 300 is accurately throttled, abnormal noise caused by the contact between the stopper rubber 9 and the bumper cap 300 is accurately suppressed.

[0051] In the aperture portion 340 according to the third embodiment, the air that has flowed into the guide path 150 through the through hole 111 passes through the third side gap 353 and the fourth side gap 354, which are two gaps, and then flows out into the discharge path 160 (see FIG. 2) through the central gap 355, which is one gap. In other words, the air that has flowed into the guide path 150 passes through two gaps provided on the upstream side and then flows out into the discharge path 160 through one gap provided on the downstream side. However, the number of gaps provided on the upstream side and the number of gaps provided on the downstream side are not limited to 2 and 1 respectively, and may be, for example, 3 and 2.

[0052] <Fourth Embodiment> FIG. 12 is a view showing an example of a view of the bumper cap 400 according to the fourth embodiment as seen from the first side in the axial direction. The bumper cap 400 according to the fourth embodiment is different from the bumper cap 100 according to the first embodiment in that the annular portion 410 corresponding to the annular portion 110 is different. Hereinafter, the differences from the first embodiment will be described. The same components in the first embodiment and the fourth embodiment are denoted by the same reference numerals, and detailed descriptions thereof are omitted.

[0053] The annular portion 410 has a first side convex portion 414 that protrudes from the first surface 113, which is the surface on the first side, to the first side (see FIG. 2). The first side convex portion 414 is provided over the entire circumference in the circumferential direction and extends from the central portion of the annular portion 410 to the cylindrical portion 120 in the radial direction. However, in the annular portion 410, a recess 417 that is recessed from the surface on the first side of the first side convex portion 414 to the second side is formed in the first side convex portion 414. A plurality (six in FIG. 12) of the recesses 417 are formed in the circumferential direction.

[0054] The recess 417 has an arc shape when viewed in the axial direction, with both ends 418 arranged on the inner side and the central portion 419 formed to connect to the discharge passage 160 (see FIG. 2). Regarding the circumferential position, for example, both ends 418 are located near the position where the inner convex portion 122 is provided, and the central portion 419 is located at the center between adjacent inner convex portions 122. Also, it can be exemplified that the axial size of the recess 417 is the same as the axial size of the first side convex portion 414.

[0055] In the bumper cap 400 configured as described above, air passing through the through-hole 111 flows into the recess 417 from both ends 418 of the recess 417. The air flowing in from both ends 418 of the recess 417 merges at the central portion 419 and then flows out to the discharge passage 160 (see FIG. 2). Therefore, the recess 417 functions as a guide passage 450 for guiding the air flowing in from the through-hole 111 to the discharge passage 160. Also, the recess 417 functions as a throttle portion 440 for narrowing the flow path area of the air flowing in from the through-hole 111.

[0056] In the bumper cap 400 configured as described above, since the air generated due to the contact of the stopper rubber 9 (see FIG. 1) with the second surface 112 (see FIG. 2) of the annular portion 410 is throttled at the throttle portion 440, abnormal noise caused by the contact between the stopper rubber 9 and the bumper cap 400 is suppressed. Also, when the suspension device 1 extends, even if dust is mixed in the air sucked into the dust cover 8 due to a decrease in the amount of entry of the cylinder portion 10 (see FIG. 1) into the dust cover 8, the dust cannot reach the dust lip 92 (see FIG. 2) of the oil seal 80 without passing through the throttle portion 440. Therefore, the bumper cap 400 can suppress dust from flowing into the dust lip 92 of the oil seal 80 and the dust cover 8. Also, by changing the flow path area of the throttle portion 440 (in other words, the width and depth of the recess 417) according to the frequency of the abnormal noise generated due to the contact of the stopper rubber 9 with the second surface 112 of the annular portion 410, abnormal noises of various suspension devices 1 can be suppressed.

[0057] Here, the throttle portion 440 has both ends 418 as an example of two inlets for narrowing the flow path area of the air flowing in from the through hole 111, and a central portion 419 as an example of a confluence portion for confluencing the fluid flowing in from both ends 418. As a result, since the air generated due to the stopper rubber 9 (see FIG. 1) contacting the bumper cap 400 is accurately throttled, the abnormal noise caused by the contact between the stopper rubber 9 and the bumper cap 400 is accurately suppressed.

[0058] <Fifth Embodiment> FIG. 13 is a diagram showing an example of a bumper cap 500 according to the fifth embodiment. FIG. 13(a) is an example of a perspective view of the bumper cap 500 viewed from the second side, and FIG. 13(b) is an example of a view of the bumper cap 500 viewed from the outside in the radial direction. The bumper cap 500 according to the fifth embodiment is different from the bumper cap 100 according to the first embodiment in that an annular portion 510 corresponding to the annular portion 110 is different. Hereinafter, the differences from the first embodiment will be described. The same components in the first embodiment and the fifth embodiment are denoted by the same reference numerals, and the detailed description thereof will be omitted.

[0059] The annular portion 510 has a second-side convex portion 511 (an example of one-side convex portion) protruding from the second surface 112 to the second side. A plurality (three in FIG. 13) of the second-side convex portions 511 are provided at equal intervals in the circumferential direction. The second-side convex portions 511 are provided over the entire area of the second surface 112 in the radial direction. Further, the second-side convex portions 511 are provided over an angular range of 40 degrees in the circumferential direction, and the circumferential shape viewed from the outside is arc-shaped.

[0060] In the bumper cap 500 configured as described above, when the suspension device 1 is compressed, a part of the air generated due to the stopper rubber 9 (see FIG. 1) contacting the second-side convex portion 511 of the annular portion 510 also flows to the outside of the stopper rubber 9 through the recess between the adjacent second-side convex portions 511. As a result, the inflow amount into the bumper cap 500 is reduced. As a result, the abnormal noise caused by the contact between the stopper rubber 9 and the bumper cap 500 is further suppressed.

[0061] Note that, by forming a guide path 150 (see FIG. 2) on the first side of the second convex portion 511 and providing a throttle portion 140 (see FIG. 2), when the flow path area of the guide path 150 in the bumper cap 100 according to the first embodiment is made the same, the bumper cap 500 can be miniaturized. In addition, the second convex portion 511 may be applied to bumper caps according to other embodiments (for example, the bumper cap 200).

[0062] <Sixth Embodiment> FIG. 14 is a diagram showing an example of a bumper cap 600 according to the sixth embodiment. FIG. 14(a) is an example of a perspective view of the bumper cap 600 as viewed from the second side, and FIG. 14(b) is an example of a view of the bumper cap 600 as viewed from the outside in the radial direction. The bumper cap 600 according to the sixth embodiment is different from the bumper cap 500 according to the fifth embodiment in that an annular portion 610 corresponding to the annular portion 510 is different. Hereinafter, the differences from the fifth embodiment will be described. The same components in the fifth and sixth embodiments are denoted by the same reference numerals, and detailed descriptions thereof are omitted.

[0063] The annular portion 610 has a first side recess 611 (an example of a recess) recessed from the second surface 112 to the first side between adjacent second convex portions 511. A plurality (three in FIG. 14) of the first side recesses 611 are provided at equal intervals in the circumferential direction. The first side recesses 611 are provided over the entire area of the second surface 112 in the radial direction. Further, the first side recesses 611 are provided over an angular range of 25 degrees in the circumferential direction.

[0064] In the bumper cap 600 configured as described above, when the suspension device 1 compresses, a part of the air generated due to the stopper rubber 9 (see Fig. 1) contacting the second side convex part 511 of the annular part 610 flows outside the stopper rubber 9 through the recess between the adjacent second side convex parts 511. When flowing through the first side recess 611, the inflow amount into the bumper cap 600 is further reduced. As a result, the abnormal noise caused by the contact between the stopper rubber 9 and the bumper cap 600 is further suppressed.

[0065] Note that the annular part 610 of the bumper cap 600 shown in Fig. 14 has the second side convex part 511 and the first side recess 611, but it may not have the second side convex part 511. Since the annular part 610 has the first side recess 611, when the suspension device 1 compresses, a part of the air generated due to the stopper rubber 9 (see Fig. 1) contacting the second surface 112 of the annular part 610 can be sent outside the stopper rubber 9 through the first side recess 611. As a result, the inflow amount into the bumper cap 600 is reduced, and the abnormal noise caused by the contact between the stopper rubber 9 and the bumper cap 600 is suppressed.

Explanation of reference numerals

[0066] 1… Suspension device, 2… Buffer device, 8… Dust cover, 9… Stopper rubber, 10… Cylinder part, 12… Outer cylinder, 20… Rod, 30… Piston part, 100, 200, 300, 400, 500, 600… Bumper cap, 110, 410, 510, 610… Annular part (an example of an annular part), 111… Through hole, 114… First side convex part (an example of the other side convex part), 115… Third surface, 116… Fourth surface, 120… Cylindrical part (an example of a cylindrical part), 122… Inner convex part, 140, 170, 180, 190, 240, 340, 440… Throttle part, 150… Guide path, 160… Discharge path, 183… Inner protruding part, 184… Outer protruding part, 241… First direction part, 242… Second direction part, 243… Circumferential direction part, 253… Third side gap, 254… Fourth side gap, 255… Central gap, 343… Circumferential direction part, 353… Third side gap (an example of a branch part), 354… Fourth side gap (an example of a branch part), 355… Central gap (an example of a confluence part), 417… Concave part, 418… Both ends (an example of an inlet), 419… Central part (an example of a confluence part), 511… Second side convex part (an example of one side convex part), 611… First side concave part (an example of a concave part)

Claims

1. A through-hole through which a rod protruding from a cylinder portion passes is formed, and an annular portion disposed on one side in the axial direction of the rod with respect to the cylinder portion, and a cylindrical portion protruding from the outer peripheral portion of the annular portion to the other side in the axial direction and covering the outer peripheral surface of the cylinder portion, and comprising the annular portion has a plurality of other-side convex portions protruding to the other side, and forms a guide path for guiding the fluid flowing in from the through-hole between the adjacent other-side convex portions to the cylindrical portion, the cylindrical portion has a plurality of inner convex portions protruding inward, and forms a discharge path for discharging the fluid guided by the guide path between the adjacent inner convex portions to the outside, further comprising a throttle portion provided in the guide path for narrowing the flow path area of the fluid flowing in from the through-hole, a bumper cap.

2. The throttle portion has a flow path extending in the circumferential direction. The bumper cap according to claim 1.

3. The throttle portion has a flow path extending in the circumferential direction and a direction intersecting the circumferential direction. The bumper cap according to claim 1.

4. The throttle portion includes a primary throttle portion for narrowing the flow path area of the fluid flowing in from the through-hole, an expansion portion for expanding the flow path area of the fluid that has passed through the primary throttle portion, and a secondary throttle portion for narrowing the flow path area of the fluid that has passed through the expansion portion, and has The bumper cap according to claim 1.

5. The throttle portion includes a branch portion for branching the fluid flowing in from the through-hole, and a confluence portion for confluencing the fluid branched at the branch portion, and has The bumper cap according to claim 1.

6. The throttle portion has two inlets for narrowing the flow path area of the fluid flowing in from the through-hole, and a confluence portion for confluencing the fluid flowing in from the two inlets, and has The bumper cap according to claim 1.

7. The annular portion has at least one of a one-side convex portion protruding to the one side from the surface on the one side and a concave portion recessed to the other side from the surface on the one side. The bumper cap according to claim 1.

8. A cylinder portion, and the bumper cap according to any one of claims 1 to 7 attached to the cylinder portion, a shock absorber comprising.

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