Dust cover and shock absorber

Abstract

Provided are a dust cover suppressing the shifting of a band, and a shock absorber provided with the dust cover. A second end part, to which the other end side in the axial direction of a cylindrical part is connected, and a third end part, to which one end side in the axial direction of the cylindrical part is connected, are formed on one end-side fixing part of the dust cover. The band is wound between the second end part and the third end part protruding radially outward, so that the band can be prevented from shifting in the axial direction and the one end-side fixing part of the dust cover can be prevented from coming off from a band fastening part of a flange part.

Description

Dust cover and shock absorber

[0001] The present invention relates to a dust cover and a shock absorber.

[0002] Patent Document 1 discloses a shock absorber 1 in which a rod-side fixing portion 32 of a dust cover 41 is fixed to an outer periphery 26 of a rod cover 25 by a band 34 .

[0003] Japanese Patent Application Laid-Open No. 2019-132295

[0004] In the shock absorber described above, if the rod cover is eliminated, it is necessary to cover the piston rod with a dust cover. In this case, the rod-side fixing portion (one-end fixing portion) of the dust cover is fixed to a flange portion fixed to the tip end (one-end end) of the piston rod using a band. However, because the width of the band fastening portion on the radial outer side of the flange portion, which fastens the band, is narrow (its axial length is short), there is a risk that the band may shift in the axial direction.

[0005] An object of the present invention is to provide a dust cover that prevents a band from slipping, and a shock absorber that includes the dust cover.

[0006] The dust cover of the present invention is characterized by comprising: a bellows portion having peaks and valleys; a first wall portion connected to a first end formed at one axial end of the bellows portion and formed so as to extend from the radially inner side to the radially outer side; a cylindrical portion connected to a second end formed at the radially outer end of the first wall portion and formed with a recess that is recessed radially inward in at least a portion of the axial direction; a second wall portion connected to a third end formed at the axial end of the cylindrical portion and formed so as to extend from the radially outer side to the radially inner side; and an inclined portion connected to a fourth end formed at the radially inner end of the second wall portion and formed so as to extend at an angle from the radially inner side to the radially outer side. a first wall portion connected to a first end formed at an end of the bellows portion on one axial end side, extending from the radially inner side to the radially outer side, and abutting a first abutment surface on the other axial end side of the flange portion; a cylindrical portion connected to a second end formed at an end of the first wall portion on the radially outer side, and having a recess that is recessed radially inward in at least a portion of the axial direction in a natural state, and abutting the radially outer side of the flange portion; a second wall portion connected to a third end formed at an end of the cylindrical portion on one axial end side, extending from the radially outer side to the radially inner side, and abutting a second abutment surface on the axially one end side of the flange portion; and an inclined portion connected to a fourth end formed at an end of the second wall portion on the radially inner side, and extending at an angle from the radially inner side to the radially outer side,

[0007] According to one embodiment of the present invention, it is possible to provide a dust cover that prevents a band from slipping, and a shock absorber that includes the dust cover.

[0008] 1 is a cross-sectional view of the shock absorber taken along an axial plane according to the present embodiment, showing a fixed portion of one end of the dust cover and an outer end of the flange portion in the radial direction in a natural state before fastening the band, and an enlarged view of a portion A in FIG.

[0009] An embodiment of the present invention will be described with reference to the accompanying drawings. Here, a twin-tube, horizontally-mounted uniflow hydraulic shock absorber 1 (hereinafter referred to as "shock absorber 1") is illustrated as an example, which is provided as a yaw damper between the carbodies of a railway vehicle. For convenience, the left side in Fig. 1 is referred to as one axial end side, the right side in Fig. 1 is referred to as the other axial end side, the upper side in Fig. 2 is referred to as the radially outer side, and the lower side in Fig. 2 is referred to as the radially inner side.

[0010] As shown in Figure 1, the shock absorber 1 has a cylinder 2 in which an inner cylinder 3 and an outer cylinder 4 are arranged coaxially. The shock absorber 1 has an annular reservoir 5 formed between the inner cylinder 3 and the outer cylinder 4 of the cylinder 2. The shock absorber 1 has a closing member 6 that closes the ends of the inner cylinder 3 and the outer cylinder 4 on one axial end side. The closing member 6 functions as a rod guide that guides a piston rod 10. The shock absorber 1 has a closing member 7 that closes the ends of the inner cylinder 3 and the outer cylinder 4 on the other axial end side. The closing member 7 has a closing portion 8 that closes the end of the inner cylinder 3 on the other axial end side, and a closing portion 9 that closes the end of the outer cylinder 4 on the other axial end side.

[0011] A piston 13 is inserted inside the inner cylinder 3, dividing the interior of the inner cylinder 3 into a first chamber 11 at one axial end and a second chamber 12 at the other axial end. The other axial end of a piston rod 10 is fixed to the piston 13. The one axial end of the piston rod 10 is inserted into the closing member 6 and extends to the outside of the cylinder 2. The shock absorber 1 has a passage 18 that is provided in the closing member 7 and that connects the second chamber 12 and the reservoir 5. A check valve 19 is provided in the passage 18 and only allows the flow of hydraulic fluid from the reservoir 5 to the second chamber 12.

[0012] The shock absorber 1 has a check valve 14 attached to the piston 13 and allowing only the flow of hydraulic fluid from the second chamber 12 to the first chamber 11. The shock absorber 1 has a passage 15 attached to the closing member 6 and connecting the first chamber 11 to the reservoir 5. The shock absorber 1 has a valve mechanism 16 attached to the passage 15 and regulating the flow of hydraulic fluid from the first chamber 11 to the reservoir 5. The first chamber 11 and the second chamber 12 are filled with hydraulic fluid as a hydraulic fluid. The reservoir 5 is filled with hydraulic fluid and gas as a hydraulic fluid.

[0013] The shock absorber 1 is fixed to the blocking portion 9 and has a mounting eye 21 that is connected to one of the car bodies of the railway vehicle. A pin 23 is attached to the mounting eye 21 via a bushing 22. On the other hand, the shock absorber 1 has a flange portion 31 that is fixed to the tip portion (the end portion on one end side) of the piston rod 10. The shock absorber 1 has a mounting eye 25 that is fixed to the flange portion 31 and the piston rod 10 and is connected to the other car body of the railway vehicle. A pin 27 is attached to the mounting eye 25 via a bushing 26.

[0014] The shock absorber 1 has a dust cover 41 that covers the piston rod 10 protruding from the blocking member 6. The dust cover 41 has a bellows portion 42 in which peaks 43 and valleys 44 are alternately arranged in the axial direction, a one-end fixing portion 51 connected to one end of the bellows portion 42, and an other-end fixing portion 45 connected to the other axial end of the bellows portion 42. The one-end fixing portion 51 is fixed by a band 52 to a band fastening portion 33 (outer cylindrical surface) formed on the radially outer end 32 (thin portion) of the flange portion 31. On the other hand, the other-end fixing portion 45 is fixed by a band 46 to the outer peripheral surface 17 of one end of the outer cylinder 4. The dust cover 41 is a resin molded product.

[0015] As shown in Fig. 2 , the one-end fixing portion 51 has a first end portion 53 formed at one axial end (valley portion 44) of the bellows portion 42. The one-end fixing portion 51 has a first wall portion 54 connected to the first end portion 53 and formed to extend radially outward from the first end portion 53 (radially inner side). The first wall portion 54 abuts against the first abutment surface 34 of the flange portion 31 when the one-end fixing portion 51 is fastened to the flange portion 31 by the band 52 (hereinafter referred to as the "attached state") (see Fig. 3 ). The first abutment surface 34 is formed on the end surface of the radially outer end portion 32 of the flange portion 31 on the other axial end side.

[0016] The one-end fixing portion 51 has a second end 55 formed at the radially outer end of the first wall portion 54. The first wall portion 54 is inclined so that the first end 53 is located closer to the other axial end (to the "right side" in FIG. 2 ) than the second end 55 when the dust cover 41 is in a natural state (a state in which no external force is acting, hereinafter referred to as the "natural state"). The radial length of the first wall portion 54 is shorter than the radial length from the peaks 43 to the valleys 44 of the bellows portion 42.

[0017] The one-end fixing portion 51 has a cylindrical portion 56 that is connected to the second end 55 and extends from the second end 55 (the other axial end) toward the one axial end. In the natural state (see FIG. 2 ), the cylindrical portion 56 has a recess 57 that is recessed radially inward at the axial center. On the other hand, in the attached state, the cylindrical portion 56 abuts against the band fastening portion 33 of the flange portion 31. Note that, although FIG. 2 shows the cylindrical portion 56 formed in a recessed shape over its entire length, the recess 57 can also be formed by recessing only the axial center portion radially inward.

[0018] The one-end fixing portion 51 has a third end portion 58 formed at one end of the cylindrical portion 57. The third end portion 58 and the second end portion 55 are formed to protrude radially outward relative to the cylindrical portion 56. In other words, the second end portion 55 and the third end portion 58 have a larger outer diameter than the cylindrical portion 56. The one-end fixing portion 51 has a second wall portion 59 connected to the third end portion 58 and formed to extend radially inward from the third end portion 58 (radially outer side). In other words, the one-end fixing portion 51 has a first wall portion 54 extending radially inward from the end portion (second end portion 55) on the other end side of the cylindrical portion 56, and a second wall portion 59 extending radially inward from the end portion (third end portion 58) on one end side of the cylindrical portion 56.

[0019] In the attached state (see FIG. 3 ), the second wall portion 59 abuts against the second abutment surface 35 of the flange portion 31. The second abutment portion 35 is formed on an end surface of the radially outer end portion 32 of the flange portion 31 at one axial end. The second abutment portion 35 is disposed on a plane perpendicular to the axis of the dust cover 41 (hereinafter referred to as the “axis-perpendicular plane”). Here, the first abutment surface 34 is disposed on the axis-perpendicular plane. The flange portion 31 has a thick-walled portion 38 on an end surface 36 at one axial end that is inclined with respect to the axis-perpendicular plane so that the thickness becomes thinner (the axial length becomes shorter) from the radially inner side to the radially outer side. As a result, an annular step 37 is formed between the second abutment surface 35 and the end surface 36 at one axial end of the flange portion 31.

[0020] The one-end fixing portion 51 has a fourth end 60 formed at a radially inner end of the second wall portion 59. The second wall portion 59 is inclined so that, in its natural state, the fourth end 60 is located closer to one axial end (the "left side" in FIG. 2 ) than the third end 58. In the one-end fixing portion 51 in its natural state, the axial distance between the first end 53 and the fourth end 60 is longer than the axial distance between the second end 55 and the third end 58. In other words, the one-end fixing portion 51 is formed so that the first wall portion 54 and the second wall portion 59 open radially inward in its natural state.

[0021] The one-end fixing portion 51 has an inclined portion 61 connected to the fourth end 60 and extending radially outward from the fourth end 60. The inclined portion 61 inclines from the radially inner side toward the radially outer side, moving away from the second wall portion 59. The one-end fixing portion 51 has a notch portion 62 (slit) extending with a constant width from the radially outer end of the inclined portion 61 (the open end of the one-end fixing portion 51) toward the radially inner side. This allows the one-end fixing portion 51 to open the notch portion 62 and expand the diameter of the open end when the dust cover 41 is attached. Note that multiple notches 62 may be formed in the one-end fixing portion 51.

[0022] Next, we will explain the procedure for attaching the dust cover 41 to the shock absorber 1 body. First, the shock absorber 1 body is inserted into the opening of the one-end fixing portion 51 of the dust cover 41 from the other end where the mounting eye 21 is provided. At this time, the cutout portion 62 is opened to expand the diameter of the open end of the one-end fixing portion 51, so that the pin 23 attached to the mounting eye 21 can be easily inserted into the dust cover 41.

[0023] Next, the shock absorber 1 body is protruded from the other-end fixing portion 45 of the dust cover 41. As a result, the other-end fixing portion 45 of the dust cover 41 is fitted onto the outer peripheral surface 17 of the outer cylinder 4. Next, the other-end fixing portion 45 of the dust cover 41 is positioned in the axial direction relative to the outer cylinder 4, and the band 46 wrapped around the outer periphery of the other-end fixing portion 45 of the dust cover 41 is tightened. As a result, the other-end fixing portion 45 is pressed radially inward and fastened to the end portion on one axial end side of the outer cylinder 4. The timing for tightening the band 46 may be arbitrary, and may be, for example, when tightening the band 52 on one axial end side.

[0024] 2, the flange portion 31 of the shock absorber 1 body is inserted into the opening of the one-end fixing portion 51 of the dust cover 41. In this embodiment, the cutout portion 62 is opened to expand the diameter of the open end of the one-end fixing portion 51, thereby making it possible to easily insert the flange portion 31 into the one-end fixing portion 51.

[0025] Next, the one-end fixing portion 51 of the dust cover 41 is positioned in the axial direction (the "left-right direction" in FIG. 2 ) relative to the flange portion 31. In this embodiment, as shown in FIG. 2 , the cylindrical portion 56 of the one-end fixing portion 51 and the band fastening portion 33 of the flange portion 31 are opposed to each other with their axial centers aligned. Furthermore, in this embodiment, the radially outer end portion 32 of the flange portion 31 fits between the first wall portion 54 and the second wall portion 59 of the one-end fixing portion 51, making it easy to position the one-end fixing portion 51 in the axial direction relative to the flange portion 31.

[0026] Next, the band 52 is wrapped around the outer periphery of the one-end fixing portion 51 of the dust cover 41. In this embodiment, the band 52 is wrapped around the one-end fixing portion 51 between the second end 55 and the third end 58 that protrude radially outward from the tubular portion 56 of the one-end fixing portion 51, so that the band 52 can be easily positioned in the axial direction with respect to the one-end fixing portion 51 of the dust cover 41 and the band fastening portion 33 of the shock absorber 1 body. Next, the band 52 wrapped around the outer periphery of the one-end fixing portion 51 of the dust cover 41 is tightened. As a result, the tubular portion 56 of the one-end fixing portion 51 is pressed radially inward and fastened to the band fastening portion 33 of the flange portion 31.

[0027] 3, both axial ends of the cylindrical portion 56 of the one-end fixing portion 51 are in close contact with the band fastening portion 33 (outer cylindrical surface) of the flange portion 31, eliminating the recess 57 and making the cylindrical portion 56 flat over the entire axial length. As a result, the first wall portion 54 of the one-end fixing portion 51 is pressed against the first abutment surface 34 of the flange portion 31, and is inclined with respect to the plane perpendicular to the axis so that the second end 55 is positioned closer to the other axial end than the first end 53, in other words, so that the first end 53 is closer to the first abutment surface 34 than the second end 55.

[0028] On the other hand, the second wall portion 59 of the one-end fixing portion 51 is pressed against the second abutment surface 35 of the flange portion 31 and is inclined with respect to the axis-perpendicular plane so that the third end 58 is positioned closer to the one axial end than the fourth end 60, in other words, so that the fourth end 60 is recessed closer to the second abutment surface 35 than the third end 58. In this manner, the radially outer end 32 of the flange portion 31 is sandwiched in the axial direction between the pair of walls 54, 59 due to the spring force generated by the material of the dust cover 41. Furthermore, in this embodiment, because the second wall portion 59 is inclined so as to recess toward the other axial end, the fourth end 60 of the one-end fixing portion 51 can be tightly fitted into the step portion 37 of the flange portion 31.

[0029] However, in conventional dust covers, the width of the band fastening portion of the flange is limited (the axial length is short), making it difficult to axially position the one-end fixing portion relative to the flange. Also, conventional dust covers do not have a structure to prevent the band from shifting, so there is a risk that the band will shift axially relative to the one-end fixing portion and come off the flange.

[0030] In contrast, in the present embodiment, the one-end fixing portion 51 has a first wall portion 54 provided on the other axial end side of the tubular portion 56 and extending radially inward from the second end portion 55, and a second wall portion 59 provided on the one axial end side of the tubular portion 56 and extending radially inward from the third end portion 58. When the dust cover 41 is attached, the radially outer end portion 32 of the flange portion 31 is configured to fit between the first wall portion 54 and the second wall portion 59, so that the one-end fixing portion 51 of the dust cover 41 can be easily positioned axially relative to the flange portion 31.

[0031] In this embodiment, a recess 57 is formed in the tubular portion 56 of the one-end side fixing portion 51, which is recessed in the axial center when in its natural state. This makes it possible to open the axial distance between the first wall portion 54 and the second wall portion 59 toward the radially inward direction, making it easier to accept the radially outer end portion 32 of the flange portion 31 between the first wall portion 54 and the second wall portion 59.

[0032] In this embodiment, in the attached state, the cylindrical portion 56 is in close contact with the band fastening portion 33 of the flange portion 31, and the cylindrical portion 56 is flat along the entire axial length. As a result, the first wall portion 54 is pressed against the first abutment surface 34 of the flange portion 31, and the first end portion 53 on the radially inner side is inclined so as to be closer to the first abutment surface 34 than the second end portion 55 on the radially outer side. On the other hand, the second wall portion 59 is pressed against the second abutment surface 35 of the flange portion 31, and the fourth end portion 60 is inclined so as to be closer to the second abutment surface 35 than the third end portion 58.

[0033] That is, the spring force generated by the material of the dust cover 41 allows the pair of walls 54, 59 to axially clamp the radially outer end 32 of the flange 31, thereby improving the sealing performance of the dust cover 41. Furthermore, in this embodiment, the fourth end 60 is tightly fitted into the step 37 formed on the flange 31, thereby further improving the sealing performance of the dust cover 41.

[0034] In this embodiment, a notch 62 extending radially inward from the opening end (the radially outer end) is formed in the inclined portion 61 of the dust cover 41, which is the insertion port of the shock absorber 1 body.By opening the notch 62 and expanding the diameter of the inclined portion 61 (the end on the one end side of the one end side fixing portion 51), the flange portion 31 can be easily inserted into the one end side fixing portion 51 of the dust cover 41, thereby improving assembly ease.

[0035] In this embodiment, the one-end fixing portion 51 of the dust cover 41 is connected to the other axial end side of the tubular portion 56 to form a second end 55 that protrudes radially outward, and the one axial end side of the tubular portion 56 is connected to form a third end 58 that protrudes radially outward, and the band 52 is wrapped around the second end 55 and the third end 58, thereby preventing the band 52 from shifting axially and preventing the one-end fixing portion 51 of the dust cover 41 from coming off the band fastening portion 33 of the flange portion 31.

[0036] The embodiment is not limited to the above-described embodiment, and may be configured as follows, for example. In this embodiment, the second abutment surface 35 of the flange portion 31, against which the second wall portion 59 of the dust cover 41 abuts, is disposed parallel to the axis-perpendicular plane of the dust cover 41. In contrast, the second abutment surface 35 may be formed to be inclined with respect to the axis-perpendicular plane so as to extend from the radially outer side toward the radially inner side toward the other axial end side (the first abutment surface 34 side). In this case, the fourth end 60 of the one-end fixing portion 51 can be tightly fitted into the step portion 37 formed on the flange portion 31, thereby further improving the sealing performance of the dust cover 41.

[0037] The present invention is not limited to the above-described embodiments, but includes various modifications. For example, the above-described embodiments have been described in detail to clearly explain the present invention, and the present invention is not necessarily limited to those including all of the described configurations. Furthermore, it is possible to replace part of the configuration of one embodiment with the configuration of another embodiment, or to add the configuration of another embodiment to the configuration of one embodiment. Furthermore, it is possible to add, delete, or replace part of the configuration of each embodiment with other configurations.

[0038] This application claims priority to Japanese Patent Application No. 2023-117626, filed July 19, 2023. The entire disclosure of Japanese Patent Application No. 2023-117626, filed July 19, 2023, including the specification, claims, drawings, and abstract, is incorporated herein by reference in its entirety.

[0039] REFERENCE SIGNS LIST 1 shock absorber, 41 dust cover, 42 bellows portion, 43 peak portion, 44 valley portion, 53 first end portion, 54 first wall portion, 55 second end portion, 56 cylindrical portion, 57 recessed portion, 58 third end portion, 59 second wall portion, 60 fourth end portion, 61 inclined portion

Claims

1. A dust cover for use in a shock absorber comprising: a bellows portion having peaks and valleys; a first wall portion connected to a first end portion formed at one axial end of the bellows portion and formed so as to extend from the radially inner side to the radially outer side; a cylindrical portion connected to a second end portion formed at a radially outer end portion of the first wall portion and formed with a recess that is recessed radially inward in at least a portion of the axial direction; a second wall portion connected to a third end portion formed at one axial end of the cylindrical portion and formed so as to extend from the radially outer side to the radially inner side; and an inclined portion connected to a fourth end portion formed at a radially inner end portion of the second wall portion and formed so as to extend at an angle from the radially inner side to the radially outward.

2. A dust cover as claimed in claim 1, characterized in that the second end and the third end have an outer diameter larger than that of the cylindrical portion.

3. A dust cover as claimed in claim 1 or 2, characterized in that the first wall portion is inclined so that the first end is located closer to the other axial end than the second end, and the second wall portion is inclined so that the fourth end is located closer to one axial end than the third end.

4. A dust cover as claimed in claim 1 or 2, characterized in that the inclined portion has a notch portion formed so as to extend radially inward from the radially outer end.

5. A shock absorber comprising: a cylinder in which a working fluid is sealed; a piston rod having one end protruding from the cylinder; a flange portion provided at one end of the piston rod and protruding radially outward; a dust cover having one end fixed to the flange portion and the other end fixed to the cylinder; and a band for fixing the dust cover to the flange portion, wherein the dust cover comprises a bellows portion having peaks and valleys; a first wall portion connected to a first end portion formed at one axial end of the bellows portion, formed to extend from the radial inside to the radial outside, and abutting against a first abutment surface on the other axial end side of the flange portion; a cylindrical portion connected to a second end portion formed at a radially outer end of the first wall portion, formed with a recess such that at least a portion of the axial direction is recessed radially inward in a natural state, and abutting against the radially outer side of the flange portion; a second wall portion connected to a third end portion formed at an end portion on one axial end side of the cylindrical portion, formed so as to extend from the radial outside to the radial inside, and abutting a second abutment surface on the axial end side of the flange portion; and an inclined portion connected to a fourth end portion formed at an end portion on the radial inside of the second wall portion, formed so as to extend at an angle from the radial inside to the radial outside, wherein the band is provided on the radial outside of the cylindrical portion.

6. A shock absorber as claimed in claim 5, characterized in that the first wall portion is inclined so that the first end is located closer to the first contact surface side than the second end.

7. A shock absorber as claimed in claim 5 or 6, characterized in that the second wall portion is inclined so that the fourth end is located closer to the second contact surface side than the third end.

8. A shock absorber as claimed in claim 5 or 6, characterized in that the second contact surface is inclined so that the radially inner side is located closer to the other axial end side than the radially outer side.

9. A shock absorber as claimed in claim 5 or 6, wherein the flange portion has a thin portion formed at the radially outer end, a thick portion having an axial length longer than the thin portion, and an annular step portion formed between the thin portion and the thick portion, and the fourth end of the dust cover abuts against the step portion.

10. A shock absorber according to claim 5 or 6, characterized in that the second end and the third end of the dust cover have an outer diameter larger than that of the cylindrical portion.

11. A shock absorber as claimed in claim 5 or 6, characterized in that the dust cover has a notch portion formed so as to extend radially inward from the radially outer end of the inclined portion.

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