Shock absorber

Abstract

A shock absorber (10; 10A) comprises: a cylinder (12); a piston rod (17) that is provided so as to be capable of moving forward and backward with respect to the cylinder (12) when a force in a compression direction or an extension direction is applied thereto; a piston (18) that can be displaced together with the piston rod (17); a flange part (21) that expands in the radial direction from the other end of the piston rod (17); an elastic member (15) that is fixed to a portion of the cylinder (12) through which the piston rod (17) penetrates, that abuts on the flange part (21) when the piston rod (17) reaches the forward limit, and that elastically deforms; and an outer wall part (32) that covers at least a part of an outer peripheral surface of the elastic member (15).

Description

buffer

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

[0002] A conventional technique related to shock absorbers is disclosed in Patent Document 1. The shock absorber disclosed in Patent Document 1 includes a cylinder, a piston rod that is provided so as to be able to advance and retreat relative to the cylinder, a piston that is fixed to one end of the piston rod and displaces, a rod guide provided at the tip of the cylinder, a flange that extends radially from the other end of the piston rod, an elastic member that is supported by the flange and comes into contact with an end plate when the piston rod reaches its forward limit, and a sensor that surrounds the elastic member and detects the amount of displacement of the piston.

[0003] When a compressive force is applied to the shock absorber, the piston rod moves forward relative to the cylinder. As the piston rod continues to move forward, the elastic member comes into contact with the rod guide. As the piston rod moves further forward, the elastic member undergoes elastic deformation, compressing in the axial direction and expanding in the radial direction. This prevents the piston rod from moving beyond its forward limit.

[0004] JP 2019-74463 A

[0005] If the piston rod advances beyond a predetermined amount, the elastic member may be deformed beyond its elastic range. To extend the life of the elastic member, it is preferable to be able to control the amount of deformation of the elastic member.

[0006] An object of the present invention is to provide a shock absorber that can control the amount of deformation of an elastic member.

[0007] As a result of extensive research, the inventors discovered that by fixing an elastic member to the portion of the cylinder through which the piston rod passes and surrounding at least a portion of this elastic member with an outer wall, it is possible to control the amount of deformation of the elastic member. The present invention was completed based on this discovery.

[0008] The present disclosure will be described below.

[0009] According to the present disclosure, there is provided a shock absorber comprising: a cylinder formed by a cylindrical body; a piston rod which is a rod-shaped member having one end facing the interior of the cylinder and the other end protruding from the cylinder and which is arranged so as to be able to advance and retreat relative to the cylinder when a force in a compression direction or an extension direction is applied; a piston which is fixed to one end of the piston rod and is displaceable relative to the cylinder together with the piston rod; a flange portion which extends radially from the other end of the piston rod; an elastic member which is fixed to a portion of the cylinder through which the piston rod passes and which abuts against the flange portion and elastically deforms when the piston rod reaches its forward limit; and an outer wall portion which is arranged in the portion of the cylinder through which the piston rod passes and which covers at least a portion of the outer peripheral surface of the elastic member.

[0010] According to the present invention, it is possible to provide a shock absorber that can control the amount of deformation of the elastic member.

[0011] Fig. 4A is a cross-sectional view of a main part of a shock absorber according to Example 1. Fig. 4B is an enlarged view of a main part of Fig. 1. Fig. 4C is a view for explaining a compression stroke of the shock absorber shown in Fig. 2. Fig. 4A is a cross-sectional view of a main part of a shock absorber according to Example 2, and Fig. 4B is a cross-sectional view of a main part of a shock absorber according to a comparative example.

[0012] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the accompanying drawings. Note that the embodiments shown in the accompanying drawings are merely examples of the present invention, and the present invention is not limited to these embodiments.

[0013] <Example 1> See Figure 1. The shock absorber 10 is, for example, a rear cushion provided at the rear of a saddle-ride type vehicle. As an example, the upper end of the shock absorber 10 is connected to the vehicle body, and the lower end is connected to the rear wheel. The shock absorber 10 may be used alone or in a plurality of units of two or more. Energy such as vibrations generated by the influence of unevenness in the road surface is attenuated as the shock absorber 10 expands and contracts, and transmission of the energy to the vehicle body and occupants is suppressed. Hereinafter, the state of the shock absorber 10 shown in Figure 1 may be referred to as the "normal state."

[0014] The shock absorber 10 comprises a first mounting portion 11 located at the upper end and attached to another portion such as the vehicle body, a cylinder 12 which is a cylindrical body supported by the first mounting portion 11, a cylinder lid portion 13 which closes the lower end of the cylinder 12, an end plate 30 provided at the lower end of the cylinder 12, an elastic member 15 fixed to the end plate 30, a second mounting portion 16 located at the lower end and attached to another portion such as the rear wheel, a piston rod 17 supported by the second mounting portion 16 and one end of which extends into the cylinder 12, and a piston rod 17. 7 and abutting the inner peripheral surface of the cylinder 12; a rod fixing nut 19 fixing the piston rod 17 to the second mounting portion 16; a flange 21 supported by the second mounting portion 16 and extending radially; a sensor 22 provided to surround the piston rod 17 from the flange 21 and for detecting the amount of displacement of the piston 18; a suspension spring 23 that urges the piston 18 in a direction to lower (move backward) relative to the cylinder 12; and a spring bearing portion 24 provided on the flange 21 and receiving the lower end of the suspension spring 23.

[0015] The first mounting portion 11 is attached to the vehicle body and supports the cylinder 12. The first mounting portion 11 may be integrally provided with a damping force generating portion 26 for generating a damping force separately from the piston 18, and a bladder 25 into which oil filled in the cylinder 12 can flow.

[0016] 2, the cylinder 12 has an inner cylindrical portion 12a formed in a cylindrical shape with the piston 18 abutting against its inner peripheral surface, and an outer cylindrical portion 12b, which is a cylindrical body provided on the outer periphery of the inner cylindrical portion 12a. Oil is filled inside the inner cylindrical portion 12a and between the inner cylindrical portion 12a and the outer cylindrical portion 12b.

[0017] The cylinder 12 does not necessarily have to be configured as a double cylinder consisting of the inner cylinder portion 12a and the outer cylinder portion 12b, but may be configured as a single cylinder.

[0018] The cylinder lid 13 is provided along both the inner circumferential surface of the inner cylinder 12 a and the inner circumferential surface of the outer cylinder 12 b. The cylinder lid 13 includes a seal member 13 a that prevents oil from leaking out of the cylinder 12. The seal member 13 a abuts against the inner circumferential surface of the outer cylinder 12 b and is formed, for example, by an O-ring.

[0019] The end plate 30 is provided at the tip of the outer tube portion 12b and is sandwiched between the outer tube portion 12b and the cylinder lid portion 13. The end plate 30 has a guide body 31 provided with a small gap from the outer periphery of the piston rod 17, an outer wall portion 32 extending from the outer periphery end of the guide body 31 (guide portion) along the axis CL toward the flange portion 21, an inner wall portion 33 extending from the inner periphery end of the guide body 31 along the axis CL toward the flange portion 21, and a retaining portion 34 extending from the outer wall portion 32 toward the axis CL to prevent the elastic member 15 from coming out. The outer wall portion 32 and the inner wall portion 33 are formed integrally with the end plate 30.

[0020] A portion of the guide body 31 is provided along the inner peripheral surface of the outer tube portion 12b, and a portion that expands in diameter from the portion provided along this inner peripheral surface abuts against the tip of the outer tube portion 12b.

[0021] The outer wall portion 32 is formed continuously in an annular shape. However, the outer wall portion 32 may be formed discontinuously in consideration of the amount of deformation of the elastic member 15.

[0022] The inner diameter of the inner wall portion 33 is formed to be the same as the inner diameter of the guide body 31. The inner wall portion 33 is formed continuously in an annular shape. Note that the inner wall portion 33 may be formed intermittently in consideration of the amount of deformation of the elastic member 15.

[0023] With the guide body 31 as a reference, the length (height) of the outer wall portion 32 along the axis CL is longer (higher) than the length (height) of the inner wall portion 33 and shorter (shorter) than the length (height) of the elastic member 15. The position of the outer wall portion 32 is detected by the sensor 22. The distance from the outer wall portion 32 to the elastic member 15 can be set by the inner diameter of the outer wall portion 32.

[0024] The position where the retaining portion 34 is formed substantially coincides with the tip of the inner wall portion 33. The retaining portion 34 may be formed in a plurality of portions discontinuously in the circumferential direction, or may be formed continuously in the circumferential direction.

[0025] The elastic member 15 is made of a material such as rubber, and comes into contact with the flange 21 and is elastically deformed when a compressive force is applied to the shock absorber 10. In other words, any material other than rubber can be used for the elastic member 15 as long as it is capable of coming into contact with the flange 21 and being elastically deformed.

[0026] The elastic member 15 is a ring-shaped member that is continuous in the circumferential direction, and is sandwiched between an outer wall portion 32 , an inner wall portion 33 , and a retaining portion 34 .

[0027] A female screw is formed in the center of the second mounting portion 16 along the axis CL, and the piston rod 17 is screwed into the female screw. The tip of the second mounting portion 16 is formed in a stepped shape, and the center of the flange 21 is fitted into the stepped tip.

[0028] One end of the piston rod 17 is located inside the inner cylindrical portion 12 a, and the other end is screwed into the second mounting portion 16 .

[0029] A known configuration can be applied to the piston 18. For example, the piston 18 has formed therein a flow passage that generates a damping force when compressed and a flow passage that generates a damping force when extended, and a leaf spring for setting the damping force is provided at the end of each flow passage.

[0030] The rod fixing nut 19 prevents the piston rod 17 from coming off the second mounting portion 16 .

[0031] The flange 21 is a member that expands radially from the second mounting portion 16 as the center, and is fitted into a stepped portion formed in the center of the second mounting portion 16. A dust discharge hole 21 a is formed in part of the flange 21 to prevent dust from accumulating in the area surrounded by the sensor 22.

[0032] The sensor 22 has, for example, a coil 22a wound around the axis CL, a sensor inner cylinder portion 22b which is a cylinder provided on the inner circumference of the coil 22a, and a sensor outer cylinder portion 22c which is a cylinder provided on the outer circumference of the coil 22a.

[0033] When the outer wall 32 is displaced relative to the energized coil 22a, the magnetic field changes. This change in the magnetic field makes it possible to detect the position of the outer wall 32. It is also possible to detect the position of the piston 18 in the cylinder 12 relative to the position of the outer wall 32. In other words, it is possible to detect the amount of compression of the shock absorber 10.

[0034] A compression coil spring is used as the suspension spring 23. The suspension spring 23 applies a biasing force in a direction in which the flange portion 21 moves away from the cylinder 12.

[0035] The spring receiving portion 24 has a donut-shaped disk portion 24b on whose upper surface the suspension spring 23 is placed, and a cylindrical spring receiving cylindrical portion 24c that is provided from the center of the disk portion 24b along the outer peripheral surface of the sensor 22.

[0036] The disk portion 24b and the spring receiving cylindrical portion 24c may be integrally formed as one member, and are not necessarily separate bodies as in this embodiment.

[0037] Next, the operation of the shock absorber 10 will be described.

[0038] Also see Figure 3. For example, when the rear wheel rides over an uneven road surface, a compressive force acts on the shock absorber 10 (see the white arrow in Figure 3). This causes the flange 21 to approach the cylinder 12 against the force of the suspension spring 23. The second mounting portion 16, piston rod 17, piston 18, rod fixing nut 19, flange 21, and sensor 22 are displaced together relative to the cylinder 12. Meanwhile, when the flange 21 is used as a reference, the first mounting portion 11 (see Figure 1), cylinder 12, cylinder lid 13, end plate 30 (including the outer wall portion 32 and inner wall portion 33), and elastic member 15 are displaced together.

[0039] After the shock absorber 10 is compressed, a force in the expansion direction is applied to the shock absorber 10 by the biasing force of the suspension spring 23. As a result, the flange portion 21 moves away from the cylinder 12.

[0040] When the shock absorber 10 is displaced in the compression direction or the extension direction, a damping force is generated in the piston 18 or the damping force generating portion 26 (see FIG. 1), respectively. In other words, the energy input from the road surface to the shock absorber 10 is damped.

[0041] Referring to Figure 3, when a large compressive force is applied to the shock absorber 10, the tip of the outer wall portion 32 is displaced to a position where it abuts against the flange portion 21. At this time, the elastic member 15 abuts against the flange portion 21 and elastically deforms. At this time, the amount of radial deformation of the elastic member 15 is determined by the inner diameter of the outer wall portion 32. If the inner diameter of the outer wall portion 32 is small, the distance between the outer wall portion 32 and the elastic member 15 is short, and the amount of deformation of the elastic member 15 is small. If the inner diameter of the outer wall portion 32 is large, the distance between the outer wall portion 32 and the elastic member 15 is long, and the amount of deformation of the elastic member 15 is large. In other words, the amount of deformation of the elastic member 15 can be set by the inner diameter of the outer wall portion 32.

[0042] Second Embodiment Next, a second embodiment will be described with reference to the drawings.

[0043] See Fig. 4A. The shock absorber 10A according to the second embodiment does not have the sensor 22 (see Fig. 2). The shock absorber 10A according to the second embodiment uses a spring receiving portion 24A in which a disk portion 24Ab and a spring receiving cylindrical portion 24Ac are integrally formed. The other basic configuration is common to the shock absorber 10 (see Fig. 1). The same reference numerals are used for the components common to the shock absorber 10, and detailed descriptions thereof will be omitted as appropriate.

[0044] In the shock absorber 10A, the outer periphery of the piston rod 17 is surrounded by an end plate 30 or an elastic member 15 in the region between the cylinder 12 and the spring receiving portion 24A.

[0045] Please refer to Fig. 4B. Fig. 4B shows a shock absorber 110 according to a comparative example. In the shock absorber 110, an elastic member 115 is provided on the inner periphery of the spring bearing portion 24A.

[0046] The shock absorber 10 described above will be summarized below.

[0047] 2. First, the shock absorber 10 includes a cylinder 12 formed of a cylindrical body, a rod-shaped piston rod 17 having one end facing the interior of the cylinder 12 and the other end protruding from the cylinder 12 and arranged to be able to advance and retreat relative to the cylinder 12 when a force in a compressing or expanding direction is applied, a piston 18 fixed to one end of the piston rod 17 and displaceable together with the piston rod 17 relative to the cylinder 12, thereby generating a damping force, a flange 21 extending radially from the other end of the piston rod 17, an elastic member 15 fixed to a portion of the cylinder 12 through which the piston rod 17 passes (e.g., an end plate 30), and coming into contact with the flange 21 and elastically deforming when the piston rod 17 reaches its forward limit, and an outer wall 32 arranged in the portion of the cylinder 12 through which the piston rod 17 passes and covering at least a portion of the outer circumferential surface of the elastic member 15. The same applies to the shock absorber 10A according to the second embodiment.

[0048] Also see Figure 3. The elastic member 15 is supported by the cylinder 12, and its outer periphery is surrounded by an outer wall portion 32. The amount of deformation of the elastic member 15 during the compression stroke can be set by the inner diameter of the outer wall portion 32. This makes it possible to prevent the elastic member 15 from deforming excessively or insufficiently. It is possible to provide a shock absorber 10 that can control the amount of deformation of the elastic member 15.

[0049] Second, the first shock absorber 10 further includes a sensor 22 that is provided on the outer periphery of the outer wall portion 32 and that detects the amount of displacement of the piston 18 relative to the cylinder 12. The provision of the outer wall portion 32 can prevent the elastic member 15 from coming into contact with the sensor 22 when the elastic member 15 is deformed, thereby protecting the sensor 22.

[0050] Thirdly, in the second shock absorber 10, the sensor 22 detects the position of the piston 18 by detecting the position of the outer wall portion 32. The tip of the outer wall portion 32 is located closer to the flange portion 21 than the tip of the cylinder 12. The size of the sensor 22 can be made smaller than when the tip of the outer wall portion 32 is detected.

[0051] Fourth, in any of the first to third shock absorbers 10, the height of the outer wall portion 32 is set so that the tip of the piston rod 17 abuts against the flange portion 21 when the piston rod 17 reaches its forward limit. This makes it possible to suppress further deformation of the elastic member 15 when the piston rod 17 reaches its forward limit, thereby making it possible to better control the amount of deformation of the elastic member 15. The same applies to the shock absorber 10A according to the second embodiment.

[0052] Fifth, the shock absorber 10 according to any one of the first to fourth embodiments further includes an inner wall portion 33 between the piston rod 17 and the elastic member 15, which suppresses deformation of the elastic member 15 toward the piston rod 17. The formation of the inner wall portion 33 can suppress the elastic member 15 from coming off toward the inner periphery. The same applies to the shock absorber 10A according to the second embodiment.

[0053] Sixth, in the fifth shock absorber 10, the height of the inner wall portion 33 is lower than the height of the outer wall portion 32. Because the outer wall portion 32 comes into contact with the flange portion 21 first, it is possible to prevent the inner wall portion 33 from coming into contact with the rod fixing nut 19. The same applies to the shock absorber 10A according to the second embodiment.

[0054] See Fig. 4A. Seventh, in the first shock absorber 10A, the outer wall portion 32 is positioned at the outermost position when no force is applied to the piston rod 17 in the compression or extension direction. This can prevent flying stones from contacting the piston rod 17, thereby improving the protection performance of the piston rod 17.

[0055] Although the shock absorber according to the present invention has been described using the rear cushion of a saddle-ride type vehicle as an example, it can also be applied to the front fork of a saddle-ride type vehicle or a shock absorber for a passenger car, and is not limited to these types.

[0056] That is, the present invention is not limited to the examples as long as the functions and effects of the present invention are exhibited.

[0057] The shock absorber of the present invention is suitable for use as a rear cushion in a saddle-ride type vehicle.

[0058] 10, 10A... Shock absorber 12... Cylinder 15... Elastic member 17... Piston rod 18... Piston 21... Flange portion 22... Sensor 32... Outer wall portion 33... Inner wall portion

Claims

1. A shock absorber comprising: a cylinder formed by a cylindrical body; a piston rod which is a rod-shaped member having one end facing the interior of the cylinder and the other end protruding from the cylinder and which is arranged so as to be able to advance and retreat relative to the cylinder when a force in a compression or extension direction is applied; a piston fixed to one end of the piston rod and capable of displacing relative to the cylinder together with the piston rod; a flange portion extending radially from the other end of the piston rod; an elastic member which is fixed to a portion of the cylinder through which the piston rod passes and which comes into contact with the flange portion and elastically deforms when the piston rod reaches its forward limit; and an outer wall portion which is arranged in the portion of the cylinder through which the piston rod passes and which covers at least a portion of the outer peripheral surface of the elastic member.

2. The shock absorber according to claim 1, further comprising a sensor provided on the outer periphery of said outer wall portion for detecting the amount of displacement of said piston relative to said cylinder.

3. A shock absorber according to claim 2, wherein the sensor detects the displacement of the piston by detecting the position of the outer wall portion.

4. A shock absorber according to claim 1, wherein the height of the outer wall portion is set so that the tip of the piston rod abuts against the flange portion when the piston rod reaches its forward limit.

5. The shock absorber according to claim 1, further comprising an inner wall portion between said piston rod and said elastic member for suppressing deformation of said elastic member toward said piston rod.

6. The shock absorber according to claim 5, wherein the height of the inner wall portion is lower than the height of the outer wall portion.

7. The shock absorber according to claim 1, wherein the outer wall portion is positioned at the outermost position when no force is applied to the piston rod in the compression direction or extension direction.

Images