Shock absorber

Abstract

A shock absorber (D) comprises a cylinder (1), a partition wall member (20) that partitions the inside of the cylinder (1) into an operation chamber (WR) and an air chamber (G), a piston rod (2) that is inserted into the cylinder (1) so as to be capable of moving in the axial direction, a piston (3) that partitions the inside of the operation chamber (WR) into an extension-side chamber (R1) and a compression-side chamber (R2), an inner cylinder (10) that is fixed inside the cylinder (1) on one end side so as to be positioned inside the extension-side chamber (R1) and has, at the inner circumference thereof, a tapered surface (10d) that has a larger inner diameter on the other end side of the cylinder (1) than on the one end side, an elastic C-shaped segment (11) that is accommodated in the inner cylinder (10) at the outer circumference of the piston rod (2) so as to be capable of moving in the axial direction inside the inner cylinder (10), and a rebound support (12) that is installed at the outer circumference of the piston rod (2) so as to be opposite the segment (11) in the axial direction.

Description

Shock absorber

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

[0002] Conventionally, some shock absorbers are provided with a hydraulic lock mechanism that uses hydraulic pressure to mitigate impact at maximum extension.

[0003] Specifically, such a shock absorber includes a cylinder, a piston rod axially movably inserted into the cylinder, and a piston connected to the piston rod and axially movably inserted into the cylinder, and further includes: an upper chamber provided near the upper end of the cylinder and having a diameter-enlarged portion; a C-shaped segment accommodated in the upper chamber and axially movable relative to the cylinder and the piston rod; a spring that positions the segment at the lower end of the upper chamber; and a rebound support attached to the piston rod and capable of abutting against the lower end of the segment.

[0004] In the shock absorber configured as described above, when the piston rod moves in the withdrawing direction relative to the cylinder, the rebound support abuts against the segment provided on the piston rod, and the rebound support moves toward the end side of the cylinder together with the piston rod.

[0005] The upper chamber is provided at the upper end portion of the cylinder, and includes a diameter-enlarged portion whose inner diameter gradually decreases toward the upper end of the cylinder; the segment has elasticity, is provided with a split at one circumferential position, and is C-shaped when viewed from the axial direction.

[0006] When the segment is disposed in the diameter-enlarged portion of the upper chamber, the split opens widely, allowing communication between the space above the segment and the space below the segment through the split. However, when the segment moves upward in the upper chamber, leaves the diameter-enlarged portion, and moves toward the end side of the cylinder where the diameter is reduced, the diameter of the segment contracts, narrowing the split, and imparting great resistance to the flow of hydraulic oil from the space above the segment toward the space below the segment.

[0007] Therefore, a shock absorber configured in this manner, as disclosed in JP2016-534290A, exhibits a hydraulic locking function that prevents extension by reducing the diameter of the segment and increasing the pressure in the space above the segment within the cylinder when it extends near the end of the stroke.

[0008] JP2016-534290A

[0009] In a shock absorber equipped with an extension-side hydraulic locking mechanism, as mentioned above, it is necessary to form an upper chamber with an enlarged diameter portion in the cylinder. However, applying this structure to a shock absorber that does not have an outer tube on the outside of the cylinder results in the following problems.

[0010] Such shock absorbers may have suspension springs on the outer circumference of the cylinder, but if an enlarged diameter section is provided on the cylinder, the suspension springs may interfere with it, and the enlarged diameter section may get in the way, making it inconvenient to install the suspension springs.

[0011] Furthermore, if the lower end of the cylinder is blocked, the piston rod containing the piston and the partition members such as the free piston and bellows that partition the air chamber inside the cylinder must be inserted from the upper end side which has an enlarged diameter portion of the cylinder. This could cause the piston or partition members to get caught in the enlarged diameter portion, making assembly inconvenient.

[0012] Thus, applying the structure of a shock absorber equipped with an extension-side hydraulic locking mechanism directly to a shock absorber without an outer tube presents a problem in terms of ease of assembly of the shock absorber.

[0013] Therefore, the present invention aims to provide a shock absorber that can exhibit a hydraulic locking function during extension operation and improve ease of assembly.

[0014] A shock absorber that solves the above problems comprises a cylinder, a piston rod inserted into the cylinder so as to be movable in the axial direction, a piston connected to the piston rod and inserted into the cylinder so as to be movable in the axial direction, and dividing the inside of the cylinder into an extension chamber and a compression chamber, a cylindrical inner cylinder fixed inside one end of the cylinder and positioned in the extension chamber, having a tapered surface on its inner circumference where the inner diameter is larger at the other end than at the one end of the cylinder, a C-shaped elastic segment housed inside the inner cylinder and positioned on the outer circumference of the piston rod and movable in the axial direction inside the inner cylinder, and a rebound support mounted on the outer circumference of the piston rod and facing the segment in the axial direction.

[0015] With a buffer configured in this way, an inner cylinder for forming a hydraulic lock chamber is housed within the cylinder, enabling the hydraulic lock function to be performed. Furthermore, since there is no need to form a bulge in the cylinder to perform the hydraulic lock function, it becomes easier to attach the cylinder-side spring support that supports the suspension spring and other accessories attached to the outer circumference of the cylinder to the cylinder, even without an outer tube. This also increases the design flexibility of the attachment points for these accessories to the cylinder.

[0016] Furthermore, with a shock absorber configured in this way, an inner cylinder is housed within the cylinder, forming a hydraulic lock chamber within the inner cylinder. This improves the degree of freedom in setting the force that hinders the extension of the shock absorber exerted by the hydraulic lock function in the initial stages when the hydraulic lock function begins to take effect, as well as the maximum force exerted by the hydraulic lock function. It also suppresses the generation of abnormal noise due to vibration in the shock absorber when the hydraulic lock function begins to take effect.

[0017] Figure 1 is a longitudinal cross-sectional view of a buffer in one embodiment. Figure 2 is an enlarged longitudinal cross-sectional view showing a part of the buffer in one embodiment. Figure 3 is a plan view of a segment. Figure 4 is an enlarged longitudinal cross-sectional view showing a part of the buffer in a state where the rebound support is in contact with the segment. Figure 5 is an enlarged longitudinal cross-sectional view showing a part of the buffer in a state where the segment is pushed into the inner cylinder. Figure 6 is an enlarged longitudinal cross-sectional view showing a part of the buffer in a first modified example of one embodiment.

[0018] The present invention will be described based on the embodiments shown in the figures. As shown in Figure 1, the shock absorber D in one embodiment includes a cylinder 1, a piston rod 2 inserted into the cylinder 1 so as to be movable in the axial direction, a piston 3 connected to the piston rod 2 and inserted into the cylinder 1 so as to be movable in the axial direction, and dividing the inside of the cylinder 1 into an extension chamber R1 and a compression chamber R2, an inner cylinder 10 housed inside the cylinder 1, a segment 11 housed inside the inner cylinder 10 and arranged on the outer circumference of the piston rod 2 so as to be movable in the axial direction inside the inner cylinder 10, and a rebound support 12 mounted on the outer circumference of the piston rod 2 and facing the segment 11 in the axial direction.

[0019] Although not shown in the diagram, shock absorber D is, for example, installed between the vehicle body and the wheels in a vehicle to generate damping force during expansion and contraction, thereby suppressing vibrations of the vehicle body. Note that shock absorber D may be used in vehicles other than automobiles, such as saddle-type vehicles, or in equipment other than vehicles, buildings, etc.

[0020] The following describes the various parts of the buffer D. The cylinder 1 is a bottomed cylindrical shape with a bottom portion 1a, and a piston 3 is inserted inside so as to be movable in the axial direction. A free piston 20 is also inserted inside the cylinder 1 below the piston 3 so as to be movable in the axial direction, and the inside of the cylinder 1 is divided by the free piston 20 into an operating chamber WR filled with liquid and an air chamber G filled with gas. By moving the free piston 20 in the axial direction inside the cylinder 1, the free piston 20 can expand one of the operating chamber WR and the air chamber G and contract the other. In this embodiment, the free piston 20 that slides on the inner circumference of the cylinder 1 is used as a partition member to divide the inside of the cylinder 1 into the operating chamber WR and the air chamber G. However, the partition member only needs to be able to divide the inside of the cylinder 1 into the operating chamber WR and the air chamber G and allow changes in the volume ratio of the operating chamber WR and the air chamber G due to movement or expansion / contraction inside the cylinder 1, so an elastic partition such as a diaphragm or metal bellows may be used instead of the free piston 20.

[0021] The cylinder 1 is divided by the piston 3 into an extension chamber R1 above the piston 3 in Figure 1 and a compression chamber R2 below the piston 3 in Figure 1. Thus, the buffer D in this embodiment is configured as a monotube, so-called single-cylinder type buffer. The working chamber WR inside the cylinder 1 is filled with a liquid such as hydraulic oil, and the gas chamber G is filled with gas. In addition to hydraulic oil, water, aqueous solution, etc. may be used as the liquid. When a liquid is used as hydraulic oil, the gas filled in the gas chamber G should preferably be an inert gas such as nitrogen to prevent deterioration of the hydraulic oil.

[0022] A threaded portion 1b is provided on the outer circumference of the cylinder 1, extending almost its entire length, and a top-shaped cylindrical cap 21 is screw-connected to this threaded portion 1b. The cap 21 has a hole 21a at its top that allows the piston rod 2 to pass through, and a threaded portion 21b on the inner circumference of the cylindrical portion that is screw-connected to the threaded portion 1b. In addition, a cylinder-side spring retainer 30 is screw-connected to the threaded portion 1b on the outer circumference of the cylinder 1. Note that the cylinder-side spring retainer 30 may be attached to the outer circumference of the cylinder 1 by a method other than screw connection.

[0023] The cap 21 houses an annular rod guide 22 that slidably supports the piston rod 2 on its inner circumference. The rod guide 22 is housed inside the cap 21, and when the cap 21 is screwed onto the cylinder 1, it is held between the cap 21 and the cylinder 1 and fixed to the upper end of the cylinder 1. An annular sealing member 23 is provided above the rod guide 22 in Figure 1, between it and the top of the cap 21. The sealing member 23 has a seal that is in close contact with the cap 21, the rod guide 22, and the piston rod 2, preventing leakage of liquid from inside the cylinder 1. A sealing ring 24 is provided between the cylinder 1 and the cap 21, sealing the space between the cylinder 1 and the cap 21.

[0024] The piston rod 2 is cylindrical in shape, with its outer diameter reduced at the tip. It comprises a piston fitting portion 2a with the smallest diameter at the tip, a larger diameter portion 2b located above the piston fitting portion 2a in Figure 1, a stepped portion 2c at the boundary between the piston fitting portion 2a and the larger diameter portion 2b, and a threaded portion 2d on the outer circumference of the tip of the piston fitting portion 2a. A rod-side spring receiver 31 is mounted on the outer circumference of the upper end of the piston rod 2 in Figure 1. A suspension spring 32, made of a coil spring, is interposed between the cylinder-side spring receiver 30 and the rod-side spring receiver 31, on the outer circumference of the cylinder 1 and the piston rod 2. The suspension spring 32 exerts a biasing force in the direction that causes the piston rod 2 to protrude outward from the cylinder 1.

[0025] Furthermore, a bracket (not shown) is provided at the base end of the piston rod 2, which is the upper end in Figure 1, and the piston rod 2 is connected to one of the vehicle body and the wheel of a vehicle (not shown) via the aforementioned bracket (not shown). Also, a bracket (not shown) is provided at the bottom 1a of the cylinder 1, and the cylinder 1 is connected to the other of the vehicle body and the wheel via the aforementioned bracket (not shown). When the shock absorber D is interposed between the vehicle body and the wheel, the suspension spring 32 is compressed, and the vehicle body can be elastically supported by the resilient force exerted by the suspension spring 32.

[0026] In this embodiment, the shock absorber D is interposed between the vehicle body and the wheel, with the piston rod 2 connected to the vehicle body and the cylinder 1 connected to the wheel. When the vehicle travels on an uneven road surface, causing the wheel to vibrate vertically relative to the vehicle body, the piston rod 2 moves in and out of the cylinder 1, causing the shock absorber D to expand and contract, and the piston 3 moves vertically (axially) within the cylinder 1.

[0027] Next, the piston 3 is annular in shape and fitted onto the outer circumference of the piston fitting portion 2a of the piston rod 2, and is fixed to the piston rod 2 by a piston nut 9 that is screwed onto the threaded portion 2d of the piston rod 2. More specifically, as shown in Figure 1, the piston 3 is composed of an annular piston body 3a, a cylindrical portion 3b provided on the outer circumference of the lower end of the piston body 3a in Figure 1, an extension port 3c that penetrates the piston body 3a in the axial direction, and a compression port 3d that penetrates the piston body 3a in the axial direction.

[0028] As described above, the piston 3 is a bottomed cylindrical shape comprising a piston body 3a and a cylindrical portion 3b, and a piston ring 3e is mounted on its outer circumference, which slides against the inner circumference of the cylinder 1, allowing it to move axially relative to the cylinder 1. The extension port 3c and compression port 3d pass through the piston body 3a in the axial direction, connecting the extension chamber R1 and the compression chamber R2.

[0029] Next, in the lower part of the piston body 3a of the piston 3 in Figure 1, an extension damping valve 5 is stacked to open and close the outlet end of the extension port 3c. The extension damping valve 5 is a laminated leaf valve composed of multiple annular plates stacked together, and after being mounted on the outer circumference of the piston fitting portion 2a together with the piston 3, it is fixed to the piston rod 2 by a piston nut 9. The extension damping valve 5 has its inner circumference fixed to the piston rod 2 and is allowed to flex on its outer circumference. When the outer circumference is in contact with the piston body 3a, it closes the extension port 3c, and when the outer circumference is flexed and separated from the piston body 3a, it opens the extension port 3c. The extension damping valve 5 provides resistance to the flow of liquid passing through the extension port 3c from the extension chamber R1 to the compression chamber R2, while allowing the liquid to pass through. Conversely, when liquid attempts to pass through the extension port 3c from the compression chamber R2 to the extension chamber R1, it closes the valve to prevent the liquid from passing through. Furthermore, the outer diameter of the extension damping valve 5 is set such that even when the extension damping valve 5 is stacked on the lower end of the piston body 3a of the piston 3, the compression port 3d, which is located on the outer circumference side of the extension port 3c, is not blocked.

[0030] On the other hand, a compression damping valve 6, which opens and closes the outlet end of the compression port 3d, is stacked on the upper part of the piston body 3a of the piston 3 in Figure 1. The compression damping valve 6 is constructed by stacking multiple annular plates and is mounted on the outer circumference of the piston fitting portion 2a together with the piston 3, and then fixed to the piston rod 2 by a piston nut 9. The compression damping valve 6 has its inner circumference fixed to the piston rod 2 and is allowed to flex on its outer circumference. When the outer circumference is in contact with the piston body 3a, it closes the compression port 3d, and when the outer circumference is flexed and separated from the piston body 3a, it opens the compression port 3d. The compression damping valve 6 provides resistance to the flow of liquid passing through the compression port 3d from the compression chamber R2 to the extension chamber R1, while allowing the liquid to pass through. Conversely, when liquid attempts to pass through the compression port 3d from the extension chamber R1 to the compression chamber R2, the valve closes to prevent the liquid from passing through. Furthermore, the inlet end of the extension port 3c is connected to the outer circumference of the piston body 3a, and care has been taken to ensure that the extension port 3c is not blocked by the compression damping valve 6 even if the compression damping valve 6 is stacked on the upper end of the piston body 3a in Figure 1.

[0031] The inner cylinder 10 is cylindrical and is housed and fixed within the extension chamber R1 at the upper end in Figure 2, which is one end of the cylinder 1. More specifically, the inner cylinder 10 comprises a cylindrical body 10a, an annular first flange 10b provided on the outer circumference of the rod guide side end of the body 10a, which is the upper end in Figure 2, an annular second flange 10c provided on the outer circumference of the non-rod guide side end of the body 10a, which is the lower end in Figure 2, a tapered surface 10d provided on the inner circumference near the non-rod guide side end, and an annular stopper 10e provided at the non-rod guide side end below the tapered surface 10d on the inner circumference.

[0032] The outer diameter of the cylindrical body 10a is smaller than the inner diameter of the cylinder 1, and an annular gap is provided between the body 10a and the cylinder 1, which is filled with the same liquid as the liquid in the working chamber WR.

[0033] Furthermore, the first flange 10b is annular and protrudes outward from the upper outer circumference of the main body 10a in Figure 2. The outer diameter of the first flange 10b is approximately the same as the outer diameter of the cylinder 1, and when the cap 21 is screwed onto the cylinder 1, the first flange 10b is sandwiched between the upper end of the cylinder 1 in Figure 2 and the lower outer circumference of the rod guide 22 in Figure 2. When the first flange 10b is sandwiched between the cylinder 1 and the rod guide 22 in this way, the inner cylinder 10 is fixed immovably to the cylinder 1.

[0034] Furthermore, the second flange 10c is annular and protrudes outward from the lower outer circumference of the main body 10a in Figure 2. The outer diameter of the second flange 10c is approximately the same as the inner diameter of the cylinder 1. When the inner cylinder 10 is fixed to the cylinder 1, the outer surface of the second flange 10c abuts against the inner surface of the cylinder 1, and the inner cylinder 10 is radially centered by the cylinder 1 and fixed in the correct position within the cylinder 1.

[0035] Furthermore, the tapered surface 10d is formed on the inner circumference of the inner cylinder 10, extending from near the end opposite the rod guide to the center. The lower end, which is the other end of the cylinder 1, has a larger diameter than the upper end, which is the other end. The inner diameter gradually increases as you move downwards in Figure 2. The inner diameter of the main body 10a on the rod guide side of the tapered surface 10d, as shown above in Figure 2, is equal to the inner diameter of the upper end of the tapered surface 10d and is smaller than the outer diameter of the segment 11 before reduction. The maximum inner diameter of the tapered surface 10d is approximately the same as the outer diameter of the segment 11 before reduction, as described later. However, as long as it is larger than the inner diameter of the main body 10a on the side above the tapered surface 10d, it may be larger or smaller than the outer diameter of the segment 11 before reduction.

[0036] Furthermore, the stopper 10e is located on the inner circumference of the main body 10a and is directly below the lower end of the tapered surface 10d in Figure 2. The stopper 10e protrudes radially inward from the inner circumference of the lower end of the main body 10a and is formed by an annular shape and protrusions along the circumferential direction of the main body 10a. The inner diameter of the stopper 10e is smaller than the outer diameter of the segment 11 before reduction in diameter.

[0037] As shown in Figure 3, segment 11 has a split 11a at one point in the circumferential direction and is formed in an annular shape with elasticity. The split 11a of segment 11 functions as a passage connecting the inside and outside of the inner cylinder 10. Although not shown in detail, segment 11 is specifically formed by covering the outer circumference of a ring having a split made of synthetic resin or metal with molded resin. When no force is applied to segment 11 from the outer circumference, the split 11a is maintained in an open state, and the outer diameter of segment 11 in this state is larger than the inner diameter of the stopper 10e of the inner cylinder 10 and larger than the minimum inner diameter of the upper end of the tapered surface 10d. Furthermore, when segment 11 receives an external force and its circumferential ends move closer together, reducing its diameter, the circumferential width of the split 11a narrows. When the segment 11 is reduced in diameter to the point where its circumferential ends are brought into contact and the split 11a is closed, the outer diameter of the segment 11 becomes slightly smaller than the inner diameter on the upper side in Figure 2, which is smaller than the tapered surface 10d of the inner cylinder 10.

[0038] Therefore, the segment 11 is housed within the inner cylinder 10 and positioned on the inner circumference side of the tapered surface 10d. In the state where the lower end in Figure 2 is in contact with the upper end of the stopper 10e in Figure 2, the two ends in the circumferential direction are spaced far apart to ensure a large circumferential width of the split 11a.

[0039] Furthermore, as segment 11 moves upward in Figure 2 from the position where it abuts the stopper 10e relative to the inner cylinder 10, it gradually reduces in diameter following the tapered surface 10d, narrowing the circumferential width of the split 11a. When its outer circumference faces the boundary between the tapered surface 10d and the area above the tapered surface 10d on the inner circumference of the inner cylinder 10, it reduces in diameter to its maximum extent, making the circumferential width of the split 11a very small. Alternatively, the outer diameter of segment 11 in the state where both circumferential ends of segment 11 abut and close the split 11a may be made equal to the inner diameter of the inner circumference of the inner cylinder 10 above the tapered surface 10d, so that the split 11a closes when segment 11 reaches above the tapered surface 10d of the inner cylinder 10. The segment 11 is formed in a C shape by providing a split 11a at one point of the ring, but the split 11a may be provided so as to be inclined with respect to the axial direction of the segment 11, or it may be formed in a hook shape that bends in the middle, and the shape and structure can be arbitrarily changed insofar as it can function as a passage when the diameter of the segment 11 is expanded.

[0040] A spring member 13 and a cushion 14 are housed in the upper part of segment 11 in Figure 2, on the inner circumference side of the inner cylinder 10. The spring member 13 comprises a coil spring 13a, an annular push ring 13b that is fitted to the inner circumference of the segment-side end of the coil spring 13a, which is the lower end in Figure 2, and connected to the coil spring 13a, and abuts against the inner circumference of the upper end of segment 11 in Figure 2, and an annular spring holder 13c that is fitted to the inner circumference of the opposite-segment end of the coil spring 13a, which is the upper end in Figure 2, and connected to the coil spring 13a, with its outer circumference sliding against the inner circumference of the inner cylinder 10.

[0041] The push ring 13b is annular in shape and slides against the outer circumference of the piston rod 2, which is inserted inside it, and is axially movable relative to the piston rod 2. Specifically, the push ring 13b includes an annular fitting portion 13b1 that fits onto the inner circumference of the coil spring 13a, and an annular spring receiving portion 13b2 that is connected to the lower end of the fitting portion 13b1 and abuts against the segment side end of the coil spring 13a. The spring receiving portion 13b2 has a tapered portion 13b3 on its outer circumference that becomes smaller in diameter towards the bottom, and the tapered portion 13b3 abuts against the inner circumference of the upper end of the segment 11. The inner circumference of the segment 11 is closed by the push ring 13b, partitioning a hydraulic lock chamber L within the inner cylinder 10, and the inside of the hydraulic lock chamber L communicates with the outside of the inner cylinder 10 in the extension chamber R1 via the split 11a.

[0042] Since the tapered portion 13b3 is in contact with the inner circumference of the upper end of the segment 11 in this manner, when the segment 11 moves together with the push ring 13b inside the inner cylinder 10 toward the opposite side of the rod guide, it does not hinder the segment 11 from expanding in diameter along the tapered surface 10d, and the segment 11 can expand in diameter smoothly when moving toward the opposite side of the rod guide within the tapered surface 10d.

[0043] The spring holder 13c is annular in shape and slides against the outer circumference of the piston rod 2, which is inserted inside it, and is axially movable relative to the piston rod 2. Specifically, the spring holder 13c comprises an annular fitting portion 13c1 that fits onto the inner circumference of the coil spring 13a, and an annular spring receiving portion 13c2 that is connected to the lower end of the fitting portion 13c1 and abuts against the opposite end of the segment of the coil spring 13a. In this case, the outer circumference of the spring receiving portion 13c2 of the spring holder 13c slides against the inner circumference above the tapered surface 10d of the body 10a of the inner cylinder 10, but instead, the inner circumference may slide against the outer circumference of the piston rod 2.

[0044] The cushion 14 is annular, is formed of rubber or the like, and is laminated on the upper end of the spring holder 13c. When the segment 11, the spring member 13, and the cushion 14 are accommodated in the inner cylinder 10 fixed to the upper side of the cylinder 1, the spring member 13 is in a compressed state, the segment 11 is biased downward in FIG. 2 by the spring member 13 and positioned at an initial position where it abuts against the stopper 10e, and the cushion 14 is pressed against and abuts against the rod guide 22 by the spring member 13.

[0045] Next, the rebound support 12 is mounted on the outer circumference of the piston rod 2. Specifically, the rebound support 12 is annular, and includes a small diameter portion 12a that can be inserted into the inner peripheral side of the segment 11 on the outer circumference, and a large diameter portion 12b that is continuous below the small diameter portion 12a in FIG. 1 and axially faces the lower end of the segment 11 in FIG. 1.

[0046] The outer diameter of the small diameter portion 12a is smaller than the inner diameter of the segment 11 that has been reduced in diameter to the maximum extent, so that the small diameter portion 12a can enter and exit the segment 11. In addition, the axial length of the small diameter portion 12a is longer than the axial length of the segment 11.

[0047] The outer diameter of the large diameter portion 12b is larger than the inner diameter of the segment 11 that has been expanded in diameter to the maximum extent, and is smaller than the outer diameter of the segment 11 that has been reduced in diameter to the maximum extent.

[0048] The rebound support 12 is supported from the lower side in FIG. 1 by a stop ring 15 attached to the outer circumference of the piston rod 2, and movement of the rebound support 12 relative to the piston rod 2 to the lower side in FIG. 1 beyond the position where it abuts against the stop ring 15 is restricted.

[0049] The shock absorber D is configured as described above, and the operation of the shock absorber D will be explained below. First, when the shock absorber D extends, the piston rod 2 and piston 3 move upward in Figure 1 relative to the cylinder 1, causing the extension chamber R1 to contract and the compression chamber R2 to expand. The liquid in the contracted extension chamber R1 pushes open the extension damping valve 5, passes through the extension port 3c, and moves into the expanded compression chamber R2. The extension damping valve 5 resists the flow of liquid passing through the extension port 3c, causing the pressure in the extension chamber R1 to rise and act on the piston 3, generating a damping force that hinders the extension operation of the shock absorber D. When the shock absorber D extends, the piston rod 2 retracts from inside the cylinder 1, but the free piston 20 moves upward in Figure 1 relative to the volume of the piston rod 2 retracting from inside the cylinder 1, increasing the volume of the air chamber G, thereby compensating for the volume of the piston rod 2 retracting from inside the cylinder 1.

[0050] When the shock absorber D extends, if the rebound support 12 does not come into contact with the segment 11, the rebound support 12 is not subjected to the biasing force of the spring member 13 via the segment 11, and is not affected by the pressure of the hydraulic lock chamber L formed in the inner cylinder 10. Therefore, the shock absorber D can extend without its extension operation being hindered by the spring member 13 or the like.

[0051] On the other hand, when the shock absorber D extends, as shown in Figure 4, when the upper end of the small-diameter portion 12a of the rebound support 12 attached to the piston rod 2 is inserted into the segment 11 and the upper end of the large-diameter portion 12b comes into contact with the segment 11, the axial length of the small-diameter portion 12a is longer than the axial length of the segment 11, so the push ring 13b in the spring member 13 is pushed upward and separates from the segment 11, creating a gap between the push ring 13b and the segment 11. In this state, the circumferential width of the split 11a of the segment 11 is wide, and the liquid inside the inner cylinder 10 can move out of the inner cylinder 10 with almost no resistance.

[0052] From that state, as the piston rod 2 rises further relative to the cylinder 1, the segment 11 is pushed upward relative to the inner cylinder 10 fixed to the cylinder 1. As the segment 11 moves upward within the inner cylinder 10 from the state shown in Figure 4 to the state shown in Figure 5, it shrinks in diameter following the tapered surface 10d, which has a smaller inner diameter as it moves upward, and the circumferential width of the split 11a narrows. Therefore, as the segment 11 moves toward the rod guide side, which is on the inner circumference side of the tapered surface 10d and is on the upper side, the split 11a of the segment 11 narrows, creating resistance to the flow of liquid moving from the hydraulic lock chamber L, which is contracted, to the outside of the inner cylinder 10, and the pressure inside the hydraulic lock chamber L increases. As the segment 11 moves toward the rod guide side, which is on the inner circumference side of the tapered surface 10d, the degree of diameter contraction of the segment 11 increases and the circumferential width of the split 11a narrows, so the pressure inside the hydraulic lock chamber L, which is contracted in accordance with the rise of the segment 11, also increases. As the pressure in the hydraulic lock chamber L increases, the pressure in the hydraulic lock chamber L acts on the segment 11 and the rebound support 12. Therefore, the shock absorber D exerts a force that prevents the piston rod 2 from moving upward relative to the cylinder 1, due to the damping force generated by the extension damping valve 5, the increase in pressure in the hydraulic lock chamber L, and the biasing force of the spring member 13. Thus, when the rebound support 12 comes into contact with the segment 11 due to the extension operation of the shock absorber D, and the segment 11 moves toward the rod guide side relative to the inner cylinder 10, the hydraulic lock function is activated by the increase in pressure in the hydraulic lock chamber L, which prevents the extension operation, and the biasing force of the spring member 13 also prevents the extension operation.

[0053] Furthermore, as the shock absorber D continues to extend and the upper end of segment 11 exceeds the upper end of the tapered surface 10d of the inner cylinder 10, segment 11 shrinks to its maximum diameter, minimizing the circumferential width of the split 11a. This maximizes the resistance applied to the liquid flow from inside the hydraulic lock chamber L to outside the inner cylinder 10, further increasing the pressure inside the hydraulic lock chamber L and increasing the force that hinders the extension of the shock absorber D.

[0054] Therefore, when the shock absorber D extends to near the stroke end on the extension side, the segment 11 moves inside the inner cylinder 10 toward the rod guide side while narrowing the split 11a that forms a passage connecting the inside and outside of the hydraulic lock chamber L, increasing the pressure inside the shrinking hydraulic lock chamber L and generating a large force that hinders the extension side movement of the piston rod 2. In this way, when the shock absorber D extends to near the stroke end on the extension side, it exerts a force generated by the hydraulic lock function in addition to the damping force from the extension damping valve 5, suppressing the extension operation and mitigating the impact at maximum extension. In this embodiment, the shock absorber D is equipped with a spring member 13, so when the hydraulic lock function is activated, the biasing force of the spring member 13 can also be applied, allowing for an even greater force to be exerted. However, the biasing force of the spring member 13 may be reduced, or the spring member 13 may be omitted.

[0055] Furthermore, when the shock absorber D extends to near the stroke end on the extension side, and the segment 11 moves from its initial position to the rod guide side within the inner cylinder 10, and then exhibits a contraction operation, the segment 11 is pressed downward by the spring member 13 toward the opposite side of the rod guide relative to the inner cylinder 10, and quickly returns to its initial position while expanding in diameter along the tapered surface 10d. When the segment 11 returns to its initial position, the split 11a opens, allowing liquid to move into the hydraulic lock chamber L from outside the inner cylinder 10 without resistance, so the pressure inside the hydraulic lock chamber L decreases rapidly. Therefore, it is easy to return the segment 11 to its initial position when the shock absorber D contracts, and it is possible to suppress the sudden application of a large force to the piston rod 2 by the hydraulic lock function during the extension operation following the contraction operation, which would otherwise cause an impact on the piston rod 2, because the pressure inside the hydraulic lock chamber L does not drop completely.

[0056] Next, when the shock absorber D contracts, the piston rod 2 and piston 3 move downward in Figure 1 relative to the cylinder 1, causing the compression chamber R2 to shrink and the extension chamber R1 to expand. The liquid in the contracting compression chamber R2 pushes open the compression damping valve 6, passes through the compression port 3d, and moves into the expanding extension chamber R1. The compression damping valve 6 resists the flow of liquid passing through the compression port 3d, causing the pressure in the compression chamber R2 to rise and act on the piston 3, generating a damping force that prevents the shock absorber D from contracting. When the shock absorber D contracts, the piston rod 2 enters the cylinder 1, but the free piston 20 moves downward in Figure 1 relative to the volume of the piston rod 2 that enters the cylinder 1, reducing the volume of the air chamber G and compensating for the volume of the piston rod 2 that enters the cylinder 1.

[0057] As described above, the shock absorber D of this embodiment comprises a cylinder 1, a piston rod 2 inserted into the cylinder 1 so as to be movable in the axial direction, a piston 3 connected to the piston rod 2 and inserted into the cylinder 1 so as to be movable in the axial direction, and dividing the inside of the cylinder 1 into an extension chamber R1 and a compression chamber R2, a cylindrical inner cylinder 10 fixed inside one end of the cylinder 1 and positioned in the extension chamber R1, and having a tapered surface 10d on its inner circumference such that the inner diameter is larger at the other end than at the one end of the cylinder 1, a C-shaped and elastic segment 11 housed inside the inner cylinder 10 and positioned on the outer circumference of the piston rod 2 so as to be movable in the axial direction inside the inner cylinder 10, and a rebound support 12 mounted on the outer circumference of the piston rod 2 and facing the segment 11 in the axial direction.

[0058] When the buffer D configured in this way extends to near the end of the stroke on the extension side, the rebound support 12 pushes the segment 11 located inside the inner cylinder 10 housed in the cylinder 1, causing the segment 11 to shrink in diameter and move upward in Figure 2 within the inner cylinder 10. This increases the pressure inside the inner cylinder 10, exerting a force through the hydraulic locking function and suppressing the extension operation.

[0059] In this manner, the shock absorber D houses an inner cylinder 10 for forming a hydraulic lock chamber L within the cylinder 1. Therefore, there is no need to form a bulge on the cylinder 1 to perform the hydraulic lock function. As a result, even without an outer tube covering the cylinder 1, the installation of the cylinder-side spring support 30 that supports the suspension spring 32 and other accessories attached to the outer circumference of the cylinder 1 becomes easier, and the design freedom for the attachment points of these accessories to the cylinder 1 is improved. Thus, according to the shock absorber D of this embodiment, the hydraulic lock function can be performed during extension operation, and assembly ease can be improved.

[0060] Furthermore, in the buffer D of this embodiment, the inner cylinder 10 is housed within the cylinder 1, forming a hydraulic lock chamber L within the inner cylinder 10. This allows the pressure-receiving area of ​​the segment 11 and rebound support 12, which receive pressure within the hydraulic lock chamber L, to be adjusted by setting the inner diameter of the inner cylinder 10. This improves the degree of freedom in setting the force that hinders the extension of the buffer D exerted by the hydraulic lock function in the initial stages when the hydraulic lock function begins to take effect, and the maximum force exerted by the hydraulic lock function.

[0061] Furthermore, if a cylinder is provided with an enlarged diameter section to form a hydraulic lock chamber by sliding a segment against the cylinder, the pressure-receiving area of ​​the segment and rebound support may become too large, resulting in excessive force at the initial stage when the hydraulic lock function begins to engage, which could cause vibration in the shock absorber and generate abnormal noise. In contrast, in the shock absorber D of this embodiment, the inner cylinder 10 is housed within the cylinder 1, and the hydraulic lock chamber L is formed within the inner cylinder 10. This reduces the pressure-receiving area of ​​the segment 11 and rebound support 12, thereby suppressing vibration in the shock absorber D and the generation of abnormal noise at the initial stage when the hydraulic lock function begins to engage.

[0062] Furthermore, in the buffer D of this embodiment, when a free piston (partition member) 20 is housed within the cylinder 1 and divides the inside of the cylinder 1 into an operating chamber WR consisting of an extension chamber R1 and a compression chamber R2, and an air chamber G, and is configured as a monotube single-cylinder type buffer, the insertion of the free piston (partition member) 20 and the piston 3 into the cylinder 1 becomes easier, further improving ease of assembly.

[0063] Furthermore, the shock absorber D of this embodiment includes a cylinder-side spring receiver 30 mounted on the outer circumference of the cylinder 1, a rod-side spring receiver 31 mounted on the piston rod 2, and a suspension spring 32 positioned on the outer circumference of the cylinder 1 and the piston rod 2 and provided between the cylinder-side spring receiver 30 and the rod-side spring receiver 31. With the shock absorber D configured in this way, since the inner cylinder 10 for forming the hydraulic lock chamber L is housed inside the cylinder 1, there is no need to form a bulging portion on the cylinder 1 in order to perform the hydraulic lock function. Therefore, even if the suspension spring 32 is provided on the outer circumference of the cylinder 1, interference between the cylinder 1 and the suspension spring 32 can be avoided, and a protector to protect the cylinder 1 from the suspension spring 32 is also unnecessary, thus reducing manufacturing costs. Furthermore, with the shock absorber D configured in this way, it is not necessary to provide a bulging portion on the cylinder 1, which improves the degree of freedom in the installation position of the cylinder-side spring receiver 30. Additionally, by providing a threaded portion 1b on the outer circumference of the cylinder 1 and screwing the cylinder-side spring receiver 30 to the threaded portion 1b, the installation position of the cylinder-side spring receiver 30 relative to the cylinder 1 can be easily adjusted.

[0064] Furthermore, the buffer D of this embodiment includes a free piston (partition member) 20 housed within the cylinder 1 that separates the working chamber WR and the air chamber G within the cylinder 1, and the cylinder 1 has the same inner and outer diameters along its entire length. With the buffer D configured in this way, since no special processing is required to form a bulging portion on the cylinder 1, the cylinder 1 can be made into a simple pipe, thereby reducing manufacturing costs.

[0065] Furthermore, the shock absorber D of this embodiment includes an annular rod guide 22 fixed to one end of the cylinder 1 through which the piston rod 2 is inserted. The inner cylinder 10 includes a cylindrical body 10a that forms a gap between itself and the cylinder 1, a first flange 10b provided on the outer circumference of the rod guide side end of the body 10a and sandwiched between the cylinder 1 and the rod guide 22, and a second flange 10c on the outer circumference of the non-rod guide side end of the body 10a that abuts against the inner circumference of the cylinder 1.

[0066] With the shock absorber D configured in this way, the inner cylinder 10 can be fixed to the cylinder 1 by sandwiching the first flange 10b between the cylinder 1 and the rod guide 22, and the main body 10a can be centered relative to the cylinder 1 by bringing the second flange 10c into contact with the inner circumference of the cylinder 1, making it easy to fix the inner cylinder 10 and position it in the correct position, and the weight can be reduced by creating an air gap between the main body 10a and the cylinder 1.

[0067] Furthermore, the inner cylinder 10, together with the segment 11 housed inside, only needs to be able to perform a hydraulic locking function by forming a hydraulic lock chamber L within the cylinder 1 and within the extension chamber R1. Therefore, the structure and shape can be appropriately modified to that extent. Thus, it is also possible to have no gap between the cylinder 1 and the inner cylinder 10, and to have the entire outer circumference of the inner cylinder 10 in contact with the inner circumference of the cylinder 1.

[0068] Furthermore, although the inner cylinder 10 is fixed by sandwiching the first flange 10b between the cylinder 1 and the rod guide 22 as described above, it may also be fixed inside the cylinder 1 by being connected to the rod guide 22, or by being formed integrally with the rod guide 22 as shown in Figure 6, or it may be fixed to the inner circumference of the cylinder 1 by press-fitting or screw connection. In addition, the position, axial length, and inclination of the tapered surface 10d provided inside the inner cylinder 10 can also be modified in design according to the characteristics of the hydraulic locking mechanism.

[0069] In this embodiment, the shock absorber D is configured as a monotube, single-cylinder type shock absorber. However, a cylindrical tank may be provided outside the cylinder 1, in a position that does not interfere with accessories such as suspension spring supports, and equipped with a liquid chamber and an air chamber partitioned inward by a partition member. The liquid chamber inside the tank is connected to the pressure chamber to compensate for the volume of the piston rod 2 moving in and out of the cylinder 1 during expansion and contraction. Such a tank may be formed from a cylinder different from the cylinder 1 and connected to the lower end of the cylinder 1, or it may be formed from a cylinder spaced apart from the cylinder 1, with piping connecting the inside of the cylinder 1 and the liquid chamber inside the tank.

[0070] Furthermore, the buffer D may include a partition member housed within the cylinder 1 that divides a liquid chamber between the pressure chamber R2 and the air chamber G, a pressure-side damping valve provided on the partition member that resists the flow of liquid from the pressure chamber R2 to the liquid chamber, and a check valve provided on the partition member that allows only the flow of liquid from the liquid chamber to the pressure chamber R2. Also, if the buffer D includes the aforementioned tank, it may include a partition member provided between the pressure chamber R2 in the cylinder 1 and the liquid chamber in the tank, a pressure-side damping valve provided on the partition member that resists the flow of liquid from the pressure chamber R2 to the liquid chamber, and a check valve provided on the partition member that allows only the flow of liquid from the liquid chamber to the pressure chamber R2. In a buffer D equipped with a partition member, a pressure-side damping valve, and a check valve in this way, a high damping force can be generated during the contraction operation regardless of the pressure in the air chamber G.

[0071] Although preferred embodiments of the present invention have been described in detail above, modifications, alterations, and changes are permitted as long as they do not deviate from the scope of the claims.

[0072] 1...Cylinder, 2...Piston rod, 3...Piston, 10...Inner cylinder, 10a...Body, 10b...First flange, 10c...Second flange, 10d...Tapered surface, 11...Segment, 12...Rebound support, 20...Free piston (bulkhead member), 22...Rod guide, 30...Cylinder-side spring seat, 31...Rod-side spring seat, 32...Suspension spring, D...Bow absorber, G...Air chamber, R1...Extension chamber, R2...Compression chamber, WR...Actual chamber

Claims

1. A shock absorber comprising: a cylinder; a piston rod inserted into the cylinder so as to be movable in the axial direction; a piston connected to the piston rod and inserted into the cylinder so as to be movable in the axial direction, dividing the inside of the cylinder into an extension chamber and a compression chamber; a cylindrical inner cylinder fixed within one end of the cylinder and positioned within the extension chamber, having a tapered surface on its inner circumference such that the inner diameter is larger at the other end than at the one end of the cylinder; an annular, elastic segment housed within the inner cylinder and positioned on the outer circumference of the piston rod, movable in the axial direction within the inner cylinder, and having a split; and a rebound support mounted on the outer circumference of the piston rod and facing the segment in the axial direction.

2. A shock absorber according to claim 1, comprising: a cylinder-side spring receiver mounted on the outer circumference of the cylinder; a rod-side spring receiver mounted on the piston rod; and a suspension spring arranged on the outer circumference of the cylinder and the piston rod and provided between the cylinder-side spring receiver and the rod-side spring receiver.

3. A shock absorber according to claim 1, comprising a partition member housed within the cylinder and separating the working chamber and the air chamber within the cylinder, wherein the cylinder has the same inner and outer diameters along its entire length.

4. A shock absorber according to claim 1, comprising an annular rod guide fixed to one end of the cylinder and through which the piston rod is inserted, wherein the inner cylinder has a cylindrical body that forms a gap between itself and the cylinder, a first flange provided on the outer circumference of the rod guide side end of the body and sandwiched between the cylinder and the rod guide, and a second flange on the outer circumference of the non-rod guide side end of the body that abuts against the inner circumference of the cylinder.

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