Shock absorber

Abstract

A shock absorber (10) comprises: an outer tube (11), the inside of which is filled with oil; a cylinder (13) which can be displaced along an axis line (CL) with respect to the outer tube (11); a piston rod (14), at the tip end of which a piston is attached; a coil spring (16) which biases the outer tube (11) and the cylinder (13) in directions away from each other; a spring guide (30) which guides the coil spring (16) to extend and be compressed along the axis line (CL); an oil lock collar (22) that suppresses a prescribed amount or greater of compression of the coil spring (16); and an oil lock piece (23) which enters into the oil lock collar (22) at least when the coil spring (16) is compressed, and which is fixed to the tip end of the spring guide (30).

Description

Shock absorber

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

[0002] For example, a shock absorber is used in the front fork of a saddle-riding type vehicle. As a prior art related to shock absorbers, there is a technique disclosed in Patent Document 1.

[0003] As shown in Patent Document 1, the shock absorber includes an oil lock piece provided on the outer periphery of a piston rod, and an oil lock collar that surrounds the outer periphery of the oil lock piece when the compression amount exceeds a predetermined amount and suppresses further compression. The oil remaining in the region surrounded by the oil lock piece and the oil lock collar becomes a resistance, and the compression is suppressed.

[0004] The axial displacement of the oil lock collar is restricted by a stopper ring provided on the outer periphery of the piston rod.

[0005] Japanese Patent Application Laid-Open No. 2005-221037

[0006] In the shock absorber according to Patent Document 1, the stopper ring forms a groove in the piston rod and is fixed in the groove. The piston rod is a member provided across two members that expand and contract, and a large load is applied in the bending direction. In particular, a large load is applied to the groove whose diameter changes. There is room for improvement in this regard.

[0007] An object of the present invention is to provide a shock absorber that can reduce the load applied to the piston rod.

[0008] As a result of intensive studies, the inventors of the present invention have found that by fixing the oil lock piece to the tip of the spring guide, it is not necessary to form a groove for attaching the stopper ring to the piston rod, and the load applied to the piston rod can be reduced. The present invention has been completed based on this finding.

[0009] Hereinafter, the present invention will be described.

[0010] According to this disclosure, a shock absorber is provided, comprising: a substantially cylindrical outer tube filled with oil; a cylindrical cylinder provided inside the outer tube and displaceable along the axis relative to the outer tube; a piston rod attached to either the outer tube or the cylinder and having a piston attached to its tip; a coil spring that biases the outer tube and the cylinder apart from each other; a spring guide provided along the inner circumference of the coil spring and guiding the coil spring to expand and contract along its axis; an oil lock collar attached to the other of the outer tube or the cylinder and restricting the flow of oil to suppress compression of the coil spring beyond a predetermined amount; and an oil lock piece that enters the oil lock collar when the coil spring is compressed and is fixed to the tip of the spring guide.

[0011] According to the present invention, it is possible to provide a shock absorber that can reduce the load applied to the piston rod.

[0012] This is a cross-sectional view along the axis of the shock absorber according to the embodiment. This is an enlarged view of the main part of the shock absorber shown in Figure 1. This is a perspective view showing the spring guide and oil lock piece shown in Figure 1. This is a perspective view showing the spring guide shown in Figure 3. Figure 5A is a diagram illustrating the operation of the oil lock piece during the compression stroke, and Figure 5B is a diagram illustrating the operation of the oil lock piece during the extension stroke. This is a diagram illustrating the extension stroke of the shock absorber shown in Figure 2.

[0013] Embodiments of the present invention will be described below with reference to the attached drawings. In this description, "left and right" refers to the left and right relative to the occupant of the saddle-type vehicle, and "front and rear" refers to the front and rear relative to the direction of travel of the vehicle. The form shown in the attached drawings is just one example of the present invention, and the present invention is not limited to this form.

[0014] <Examples> Examples of the present invention will be described based on the drawings.

[0015] Refer to Figures 1 and 2. The shock absorber 10 is used, for example, in the front fork of a saddle-type vehicle. Figure 1 shows a cross-section of the lower part of the shock absorber 10 in its most compressed state.

[0016] The shock absorber 10 includes a substantially cylindrical outer tube 11 filled with oil, a lid member 12 that closes one end of the outer tube 11, a substantially cylindrical cylinder 13 whose tip faces into the outer tube 11, a piston rod 14 supported by the lid member 12 and whose tip extends into the cylinder 13, a nut 15 for fixing the piston rod 14 to the lid member 12, a coil spring 16 that biases the outer tube 11 and the cylinder 13 apart from each other, a spring guide 30 provided between the coil spring 16 and the piston rod 14 to guide the coil spring 16, a spring receiving member 18 provided at the tip of the cylinder 13 to receive the upper end of the coil spring 16, a cylindrical support cylinder 21 provided inside the cylinder 13, an oil lock collar 22 provided at the tip of the support cylinder 21 to suppress compression of the coil spring 16 beyond a predetermined amount, and an oil lock piece 23 fixed to the tip of the spring guide 30.

[0017] The outer tube 11 is constructed by stacking two cylindrical bodies. It has an outer tube body 11a, which is the main body with a female threaded tip, and an oil chamber constituent cylindrical body 11b provided along the inner circumferential surface of the outer tube body 11a. A passage through which oil can pass is formed between the inner circumferential surface of the outer tube body 11a and the outer circumferential surface of the oil chamber constituent cylindrical body 11b. This passage is an annularly formed oil chamber, and can also be called an annular oil chamber.

[0018] A seal 11c is provided on the inner circumferential surface of the outer tube body 11a, and the seal 11c is in contact with the outer circumferential surface of the oil chamber cylindrical body 11b.

[0019] The oil chamber cylindrical body 11b has a through hole 11d that penetrates radially. Some of the oil filling the inside of the oil chamber cylindrical body 11b may flow through the through hole 11d into the annular oil chamber. Alternatively, the oil in the annular oil chamber may flow through the through hole 11d into the inside of the oil chamber cylindrical body 11b.

[0020] Furthermore, the outer tube 11 does not necessarily require an oil chamber cylindrical body 11b to be provided inside the outer tube body 11a; it may consist only of the outer tube body 11a.

[0021] A portion of the outer surface of the lid member 12 is formed in a male thread shape and is screwed into the end of the outer tube body 11a, which is formed in a female thread shape. The lid member 12 also has a change in outer diameter at multiple points, and the stepped portion formed by the change in diameter receives the lower end (base end) of the oil chamber cylindrical body 11b. Furthermore, the lower end (one end) of the coil spring 16 is received at the stepped portion on the axis CL side from the portion receiving the oil chamber cylindrical body 11b. The piston rod 14 is also fixed to the lid member 12.

[0022] Furthermore, the inside of the lid member 12 may be provided with damping force adjustment means for adjusting the damping force.

[0023] The cylinder 13 is a substantially cylindrical member with multiple through holes 13a and 13b passing through it in the radial direction. A spring receiving member 18 is fixed to the tip of the cylinder 13, and the cylinder 13 receives the biasing force of the coil spring 16 via the spring receiving member 18.

[0024] The piston rod 14 is supported at its lower end (base) by the lid member 12, and its upper end (tip) extends into the interior of the support cylinder 21. The piston rod 14 is made up of two cylindrical members stacked on top of each other. A piston (not shown) is fixed to the tip of the piston rod 14. A damping force is generated when the piston is displaced along the inner circumferential surface of the support cylinder 21. The piston rod 14 may also be made up of a single cylindrical member or a round bar-shaped member.

[0025] Refer to Figure 2. The piston rod 14 has a general rod portion 14a, a small-diameter rod portion 14b with a smaller outer diameter than the general rod portion 14a, and a male threaded rod portion 14c at the base end that is formed in the shape of a male thread. The boundary portion between the general rod portion 14a and the small-diameter rod portion 14b has a continuously changing diameter and is formed in a tapered shape.

[0026] Of the piston rod 14, the portion other than the small-diameter rod portion 14b and the male threaded rod portion 14c is the general rod portion 14a. The general rod portion 14a has a roughly constant outer diameter.

[0027] The base end of the piston rod 14 may be directly or indirectly fixed to the cylinder 13 (see Figure 1). In this case, the tip of the piston rod 14 extends into the interior of the outer tube 11. In other words, the piston rod 14 is supported at its base end by either the outer tube 11 or the cylinder 13, and its tip extends to the other of the outer tube 11 or the cylinder 13.

[0028] The male threaded portion 14c of the rod is screwed onto the nut 15. The piston rod 14 is prevented from coming out of the cover member 12 by the nut 15. If necessary, the female thread formed on the inner circumference of the nut 15 may be a reverse thread.

[0029] Refer to Figure 1. The coil spring 16 is composed of a compression coil spring. The coil spring 16 is expandable and contractible along the outer surface of the spring guide 30, and the spring guide 30 prevents the coil from bending.

[0030] Refer to Figures 3 and 4. The spring guide 30 includes a guide cylinder portion 31 provided along the outer circumferential surface of the piston rod 14 and formed in a substantially cylindrical shape, a guide portion 32 that protrudes from the guide cylinder portion 31 to the inner circumference of the coil spring 16 (see Figure 1) and is formed along the inner circumference of the coil spring 16, an oil lock piece support portion 33 that supports the oil lock piece 23, a connecting portion 34 that connects and reinforces the guide portion 32 to the oil lock piece support portion 33, a rib 35 extending upward from the upper end (end) of the oil lock piece support portion 33, and a flange portion 36 whose outer diameter is larger than the inner diameter of the retaining ring 26 that prevents the oil lock piece 23 from coming off, thereby preventing the retaining ring 26 from coming off.

[0031] The retaining ring 26 can be constructed, for example, by a C-shaped ring.

[0032] Refer to Figure 2. The guide cylinder portion 31 has a generally constant outer diameter, while its inner diameter varies depending on the location. The inner circumferential surface of the guide cylinder portion 31 has a general guide inner diameter portion 31a that faces the outer circumference of the general rod portion 14a, and a small guide inner diameter portion 31b that has a smaller inner diameter than the general guide inner diameter portion 31a. The inner diameter of the small guide inner diameter portion 31b is smaller than the outer diameter of the general rod portion 14a and larger than the outer diameter of the small rod portion 14b.

[0033] Refer to Figure 4. The guide portions 32 are formed at equal intervals in four locations on the outer circumference of the guide cylinder portion 31. The guide portions 32 may be formed continuously in the circumferential direction, or they may be formed intermittently in two, three, or five or more locations. Furthermore, if they are formed intermittently, they do not have to be at equal intervals.

[0034] The oil lock piece support portion 33 has a tapered support portion 33a to which the tip of the connecting portion 34 is connected and which tapers in diameter toward the tip, a cylindrical support portion 33b extending from the tip of the tapered support portion 33a and having a constant wall thickness, and a wall portion 33c at the tip of the cylindrical support portion 33b that extends radially substantially perpendicular to the axis CL.

[0035] The ribs 35 are formed at four locations from the wall portion 33c toward the tip. The number of ribs 35 may be three or fewer, or five or more. A gap is formed between the tip of the rib 35 and the flange portion 36 for attaching a retaining ring 26 (see Figure 2). That is, the tip of the rib 35 is not connected to the flange portion 36. The retaining ring 26 is held in place by the upper end of the rib 35 and the lower surface of the flange portion 36.

[0036] Refer to Figure 1. The support cylinder 21 is supported, for example, by the same member that supports the cylinder 13. In this way, the support cylinder 21 is connected to the cylinder 13. Therefore, when the cylinder 13 rises relative to the outer tube 11, the support cylinder 21 also rises together with the cylinder 13. The same applies when it descends.

[0037] Refer to Figure 2. The oil lock collar 22 is a bottomed cylindrical member, with a cylindrical hole drilled in the bottom along the axis CL. A cylindrical collar 27 that contacts the piston rod 14 is fixed in the cylindrical hole. The tip of the side surface of the oil lock collar 22 is formed by a tapered surface whose inner circumferential surface widens towards the tip. This tapered surface is called the collar tapered portion 22a.

[0038] The oil lock piece 23 is provided so as to be displaceable along the axis CL between the wall portion 33c and the retaining ring 26.

[0039] Refer to Figure 3. The tip of the outer surface of the oil lock piece 23 is formed by a tapered surface whose diameter decreases towards the tip. This tapered surface is called the piece tapered portion 23a. In addition, a thinned portion 23b is formed at the tip of the oil lock piece 23, which is thinned out toward the base end. The thinned portion 23b is formed at four locations at equal intervals with respect to the circumferential direction.

[0040] Refer to Figure 2. Oil is allowed to pass through the space between the outer circumferential surface of the spring guide 30 and the inner circumferential surface of the oil lock piece 23. This oil-passable area is hereinafter referred to as the "flow channel R".

[0041] In addition, when the piston rod 14 is fixed to the cylinder 13, the oil lock piece 23 is provided on the outer tube 11. Further, ribs protruding toward the spring guide 30 may be formed on the inner peripheral surface of the oil lock piece 23.

[0042] Refer to FIG. 5A. FIG. 5A shows the oil lock piece 23 when the shock absorber 10 is most compressed during the compression stroke. When the coil spring 16 (see FIG. 1) is compressed, the oil lock collar 22 descends with respect to the piston rod 14, the spring guide 30, and the oil lock piece 23. The force of the oil in the region surrounded by the oil lock piece 23 and the oil lock collar 22 acts in a direction to press the oil lock piece 23 against the wall portion 33c. The oil in the region surrounded by the oil lock piece 23 and the oil lock collar 22 is confined within this region, suppressing further compression of the shock absorber 10. That is, when the coil spring 16 is in the most compressed state, further compression is suppressed by the oil lock piece 23 and the oil lock collar 22.

[0043] Refer to FIG. 5B. FIG. 5B shows the oil lock piece 23 during the extension stroke. When the coil spring 16 (see FIG. 1) extends, the oil lock collar 22 ascends with respect to the piston rod 14, the spring guide 30, and the oil lock piece 23. As a result, a force for oil to flow into the region surrounded by the oil lock piece 23 and the oil lock collar 22 is applied, so that the oil lock piece 23 separates from the wall portion 33c. Thereby, oil flows into the region surrounded by the oil lock piece 23 and the oil lock collar 22.

[0044] Even when the oil lock piece 23 is lifted and the tip of the oil lock piece 23 abuts against the retaining ring 26, if the cutout portion 23b is formed, oil can be more reliably flowed into the region.

[0045] Refer to Figure 6. When the coil spring 16 (see Figure 1) begins to extend from its most compressed state, it may be in the state shown in Figure 6. That is, the spring guide 30 may be displaced upward as it is pulled by the force of the oil flowing within the area enclosed by the oil lock piece 23 and the oil lock collar 22. On the other hand, when the amount of displacement of the spring guide 30 reaches a predetermined amount, the end of the small diameter inner diameter portion 31b of the guide comes into contact with the general portion 14a of the rod, and further upward movement is restricted.

[0046] The buffer 10 described above is summarized below.

[0047] Refer to Figures 1 and 3. Firstly, the shock absorber 10 includes a substantially cylindrical outer tube 11 filled with oil, a cylindrical cylinder 13 provided inside the outer tube 11 and displaceable along the axis CL relative to the outer tube 11, a piston rod 14 attached to the outer tube 11 with a piston at its tip, a coil spring 16 that biases the outer tube 11 and the cylinder 13 apart from each other, a spring guide 30 provided along the inner circumference of the coil spring 16 and guiding the coil spring 16 to expand and contract along the axis CL, an oil lock collar 22 attached to the cylinder 13 and restricting the flow of oil to suppress compression of the coil spring 16 beyond a predetermined amount, and an oil lock piece 23 that enters the inside of the oil lock collar 22 when the coil spring 16 is compressed and is fixed to the tip of the spring guide 30.

[0048] The oil lock piece 23 is fixed to the tip of the spring guide 30. As a result, there is no need to form a groove for attaching a stopper ring on the outer periphery of the piston rod 14. When a groove is formed in the piston rod 14, stress tends to concentrate at that part. Since the oil lock piece 23 can be attached without forming a groove in the piston rod 14, a shock absorber 10 that can reduce the load applied to the piston rod 14 can be provided. The same applies when the piston rod 14 is provided in the cylinder 13 and the oil lock collar 22 is provided in the outer tube 11. Also, compared to the case where a groove is provided in the piston rod 14 and the oil lock piece 23 is attached, the assembly of the shock absorber 10 is easier.

[0049] Referring to FIGS. 5A and 5B. Second, the first shock absorber 10, in which the oil lock piece 23 is provided so as to be displaceable in the direction along the axis CL. During the compression stroke, the flow of oil can be restricted, and during the extension stroke, the flow of oil can be allowed. During the compression stroke, compression beyond a predetermined amount can be suppressed, and during the extension stroke, smooth extension can be achieved.

[0050] Third, the second shock absorber 10, in which the spring guide 30 has a wall portion 33c that restricts the displacement of the oil lock piece 23 in one direction. There is no need to attach a separate member to the spring guide 30 to restrict the displacement of the oil lock piece 23, contributing to a reduction in the number of parts.

[0051] Fourth, the third shock absorber 10, in which the oil lock piece 23 restricts the flow of oil by abutting against the wall portion 33c. Excessive movement in the compression direction can be more reliably suppressed.

[0052] Fifth, any one of the first to fourth shock absorbers 10, in which a flow path portion R through which oil can pass is formed between the outer peripheral surface of the spring guide 30 and the inner peripheral surface of the oil lock piece 23. More oil can be passed during the extension stroke, and the shock absorber 10 can be smoothly operated during the extension stroke.

[0053] Sixth, in the fifth buffer 10, the flow area of ​​the flow path section R is larger than the gap formed between the outer surface of the oil lock piece 23 and the inner surface of the oil lock collar 22. This ensures that oil passage is more reliably restricted during the compression stroke and more reliably allowed to pass during the expansion / contraction stroke.

[0054] Seventh, in the fifth or sixth shock absorber 10, the spring guide 30 has a rib 35 that protrudes radially outward. By having the rib 35, the gap between the spring guide 30 and the oil lock piece 23 can be kept constant, and the oil can be passed more reliably. The same applies when the oil lock piece 23 has a rib that protrudes radially inward.

[0055] Refer to Figure 6. Eighth, in any of the first to seventh shock absorbers 10, the spring guide 30 is provided along the outer circumferential surface of the piston rod 14, and the piston rod 14 has a general rod portion 14a and a small rod portion 14b having a smaller outer diameter than the general rod portion 14a. The spring guide 30 also has a general guide inner diameter portion 31a facing the outer circumference of the general rod portion 14a and a small guide inner diameter portion 31b having a smaller inner diameter than the general guide inner diameter portion 31a. The inner diameter of the small guide inner diameter portion 31b is smaller than the outer diameter of the general rod portion 14a and larger than the outer diameter of the small rod portion 14b.

[0056] When the spring guide 30 is displaced along the outer circumferential surface of the piston rod 14, once it has been displaced by a predetermined amount, the smaller diameter portion 31b of the guide comes into contact with the general portion 14a of the rod, and the displacement is restricted. This allows for displacement of the spring guide 30 while restricting displacement exceeding a predetermined amount.

[0057] Ninthly, in the eighth buffer 10, the boundary portion between the general rod portion 14a and the small-diameter rod portion 14b has a continuously changing diameter. Compared to the case where the boundary portion is formed in a stepped shape, it is possible to reduce the concentration of stress at the boundary portion. The load on the piston rod 14 can be reduced while regulating the amount of displacement of the spring guide 30 by utilizing the shape of the piston rod 14.

[0058] Refer to Figure 2. Tenth, the eighth or ninth shock absorber further has a nut 15 for fixing the piston rod 14, and the downward movement of the spring guide 30 is restricted by the nut 15. The displacement of the spring guide 30 is restricted using the nut 15 for fixing the piston rod 14. There is no need to provide a separate part for restricting the displacement of the spring guide 30, and the displacement of the spring guide 30 can be restricted with a small number of parts.

[0059] Eleventh, in the tenth buffer 10, the lower end surface of the spring guide 30 can be tightly fitted to the nut 15, and the nut 15 suppresses oil from flowing out from the small diameter portion 31b of the guide when the end surface of the spring guide 30 is tightly fitted to it. By suppressing the oil inside the spring guide 30 from leaking out to the nut 15 side when oil lock occurs, excessive compression during the compression stroke can be prevented more reliably.

[0060] Although the shock absorber 10 according to the present invention has been described in the example of being mounted on the front fork of a saddle-type vehicle, it can also be applied to a rear cushion or to vehicles other than saddle-type vehicles. In other words, the present invention is not limited to the form shown in the examples. That is, insofar as it achieves the function and effect of the present invention, the present invention is not limited to the examples.

[0061] The shock absorber of the present invention is suitable for mounting on the front fork of a saddle-type vehicle.

[0062] 10... Shock absorber 11... Outer tube 13... Cylinder 14... Piston rod, 14a... General rod section, 14b... Small diameter rod section 15... Nut 16... Coil spring 22... Oil lock collar 23... Oil lock piece 30... Spring guide 31a... General inner diameter guide section, 31b... Small diameter guide inner diameter section 33c... Wall section 35... Rib R... Flow path section CL... Axis

Claims

1. A shock absorber comprising: a substantially cylindrical outer tube filled with oil; a cylindrical cylinder provided inside the outer tube and displaceable along the axis relative to the outer tube; a piston rod attached to either the outer tube or the cylinder and having a piston attached to its tip; a coil spring biasing the outer tube and the cylinder apart from each other; a spring guide provided along the inner circumference of the coil spring and guiding the coil spring to expand and contract along its axis; an oil lock collar attached to the other of the outer tube or the cylinder and restricting the flow of oil to prevent the coil spring from being compressed beyond a predetermined amount; and an oil lock piece that enters the oil lock collar when the coil spring is compressed and is fixed to the tip of the spring guide.

2. The shock absorber according to claim 1, wherein the oil lock piece is provided so as to be displaceable in the axial direction.

3. The shock absorber according to claim 2, wherein the spring guide has a wall portion that restricts the displacement of the oil lock piece in one direction.

4. The buffer according to claim 3, wherein the oil lock piece restricts the flow of oil by contacting the wall portion.

5. The shock absorber according to claim 1, wherein a flow path portion is formed between the outer circumferential surface of the spring guide and the inner circumferential surface of the oil lock piece, through which oil can pass.

6. The buffer according to claim 5, wherein the flow area of ​​the flow channel is larger than the gap formed between the outer surface of the oil lock piece and the inner surface of the oil lock collar.

7. The shock absorber according to claim 5, wherein the spring guide has a rib projecting radially outward, or the oil lock piece has a rib projecting radially inward.

8. The shock absorber according to claim 1, wherein the spring guide is provided along the outer circumferential surface of the piston rod, the piston rod has a general rod portion and a small rod portion having a smaller outer diameter than the general rod portion, the spring guide has a general guide inner diameter portion facing the outer circumference of the general rod portion and a small guide inner diameter portion having a smaller inner diameter than the general guide inner diameter portion, and the inner diameter of the small guide inner diameter portion is smaller than the outer diameter of the general rod portion and larger than the outer diameter of the small rod portion.

9. The buffer according to claim 8, wherein the boundary portion between the general portion of the rod and the small-diameter portion of the rod has a continuously changing diameter.

10. The shock absorber according to claim 8, further comprising a nut for fixing the piston rod, wherein the movement of the spring guide is restricted by the nut.

11. The shock absorber according to claim 10, wherein the end face of the spring guide can be in close contact with the nut, and the nut suppresses oil from flowing out of the small diameter portion of the inner diameter of the guide when the end face of the spring guide is in close contact with the nut, thereby suppressing oil from flowing out of the small diameter portion of the inner diameter of the guide.

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