Shock absorber

Abstract

To provide a shock absorber that can exert a hydraulic locking function and can be easily manufactured to reduce a manufacture cost.SOLUTION: A shock absorber D of the present invention comprises: a cylinder 1; a piston rod 2 inserted into the cylinder 1 so as to be axially movable; a piston 3 that is connected to the piston rod 2 and is movably inserted into the cylinder 1 to divide the inside of the cylinder 1 into an extension side chamber R1 and a compression side chamber R2; a case 8c that is axially immovable relative to the cylinder 1 and forms a lock chamber L axially opposite the piston 3; a support 4 attached to the outer periphery of the piston rod 2 facing the extension side chamber R1; a cushion 5 that is arranged on the outer periphery of the piston rod 2 facing the extension side chamber R1 and whose movement toward the piston side is restricted by the support 4; and a lock piece 6 that is provided on the outer periphery of the piston rod 2 on the opposite piston side of the cushion 5 so as to be axially movably and that can enter the lock chamber L.SELECTED DRAWING: Figure 2

Description

[Technical field]

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

[0002] Conventionally, a shock absorber used in a vehicle includes, for example, a cylinder, a piston rod that is movably inserted into the cylinder, and a piston that is connected to the tip of the piston rod and movably inserted into the cylinder to divide the inside of the cylinder into an extension side chamber and a compression side chamber.

[0003] In conventional shock absorbers configured in this manner, a rebound spring is attached to the outer periphery of the piston rod, with its piston side end supported. When the free end of the rebound spring is fully extended, it abuts against a rod guide that supports the piston rod, compressing the rebound spring, and the elastic force of the rebound spring cushions the impact when the piston rod is fully extended.

[0004] In recent years, there has been a trend to lower the damping force of shock absorbers when driving on good roads in order to improve the ride comfort of light and compact cars. However, the unsprung weight has become heavier due to electrification and improved exterior design, so there has been a demand for the use of oil locks that use hydraulic pressure that does not produce elastic rebound to cushion the impact when the shock absorber is fully extended.

[0005] In response to such demands, a shock absorber has been developed which has a tapered enlarged section at the end of the cylinder, a segment which holds a C-shaped elastic ring on the outer periphery of the piston rod, and a spring which urges the segment towards the piston; when the segment reaches the enlarged section and the shock absorber extends further, the tapered surface causes the elastic ring to gradually reduce in diameter, allowing the upper space partitioned by the elastic ring and the segment to function as an oil lock chamber (see, for example, Patent Document 1).

[0006] In a shock absorber configured in this manner, the segments do not reach the enlarged diameter portion when the vehicle is traveling on good roads, and a low damping force is exerted when the vehicle is traveling on good roads, without impairing the ride comfort of the vehicle. However, when fully extended, a hydraulic oil lock function is exerted, generating a high damping force to cushion the impact. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Special Publication No. 2016-534290 Summary of the Invention [Problem to be solved by the invention]

[0008] Conventional shock absorbers are able to fully meet the above-mentioned demand for reducing the impact at the extension stroke end, but they require processing to expand the cylinder diameter, and furthermore, in order to achieve the oil lock function, many parts need to be installed on the outer periphery of the piston rod. This increases the processing costs and the number of parts, resulting in problems of increased manufacturing costs and difficulty.

[0009] SUMMARY OF THE PRESENT DISCLOSURE An object of the present invention is to provide a shock absorber that can exhibit a hydraulic lock function, and that can be easily manufactured at low cost. [Means for solving the problem]

[0010] In order to achieve the above-mentioned object, the shock absorber of the present invention comprises a cylinder, a piston rod inserted into the cylinder so as to be axially movably, a piston connected to the piston rod and movably inserted into the cylinder, dividing the cylinder into an extension-side chamber filled with liquid and a compression-side chamber, a case which is immovable in the axial direction relative to the cylinder and forms a lock chamber which opens to the piston side, a support attached to the outer periphery of the piston rod facing the extension-side chamber, a cushion which is arranged on the outer periphery of the piston rod facing the extension-side chamber and whose movement towards the piston side is restricted by the support, and a lock piece which is arranged on the outer periphery of the piston rod on the opposite piston side of the cushion and is axially movably provided so as to be able to enter the lock chamber.

[0011] In the shock absorber configured in this manner, by providing a case that is immovable in the axial direction with respect to the cylinder and providing a lock piece on the piston rod, not only can the lock piece enter the lock chamber near the stroke end during extension operation to exert a hydraulic locking function and suppress the extension of the shock absorber, but also, when the extension progresses to the maximum extension, a large load is generated by the compression of the cushion, which stops the extension of the shock absorber and reduces the impact at the maximum extension. Also, with the shock absorber configured in this manner, since the hydraulic locking function can be exerted during the extension operation by adding a case and a lock piece to a general shock absorber, there is no need to provide a tapered enlarged diameter portion at the end of the cylinder or add many parts such as elastic rings, segments, and springs as in conventional shock absorbers.

[0012] The lock piece in the shock absorber may also have a piece body that is annular and disposed on the outer periphery of the piston rod to form an annular throttle passage between it and the piston rod and that can enter the lock chamber. With a shock absorber configured in this way, when the piece body enters the lock chamber, a load of a magnitude corresponding to the resistance of the throttle passage can be generated, and the load can be adjusted by setting the flow area of ​​the throttle passage, and the piece body can easily move up and down relative to the cushion due to the clearance between the inner periphery of the piece body and the piston rod, so that the cushion is smoothly compressed after the lock piece enters the lock chamber.

[0013] Furthermore, the lock piece in the shock absorber may have a sliding contact portion that is in sliding contact with the support. With a shock absorber configured in this manner, the lock piece can be centered by the support and positioned radially relative to the case and the cushion, making it easy to insert the lock piece into the case.

[0014] The lock piece in the shock absorber may have a piece body that can enter the lock chamber and has an uneven surface along the circumferential direction on the surface facing the case. According to a shock absorber configured in this way, the surface of the piece body facing the case is an uneven surface, so that even if the piece body enters deep into the lock chamber and abuts against the lower surface of the small diameter part of the rod guide that forms the bottom of the lock chamber, the entire upper surface of the piece body does not abut against the small diameter part, and the piece body is prevented from sticking to the bottom of the lock chamber. Also, when the shock absorber is fully extended and the piece body abuts against the bottom of the lock chamber and then performs a contraction operation, the piece body can quickly retreat from inside the lock chamber, and does not provide resistance to the contraction operation of the shock absorber.

[0015] The lock piece in the shock absorber may have a restricting portion at the sliding contact portion that prevents it from coming off the support. With a shock absorber configured in this manner, after the lock piece enters the lock chamber during extension and exerts its hydraulic locking function, when the direction of extension and contraction switches to contraction, the restricting portion of the lock piece prevents the lock piece from coming off the support, so that the lock piece can move together with the piston rod in a direction away from the case, and the lock piece does not remain in the lock chamber, and the hydraulic locking function can be stably exerted even when extension and contraction are repeated.

[0016] Furthermore, when the lock piece in the shock absorber moves away from the cushion in the axial direction, a gap communicating with the throttle passage is formed between the lock piece and the cushion, and the sliding contact portion may be formed by a plurality of arms extending at intervals in the circumferential direction relative to the piece body. In the shock absorber configured in this manner, after the lock piece enters the lock chamber during the extension operation to exert the hydraulic locking function, when the direction of extension and contraction is switched to perform the contraction operation and the lock piece leaves the lock chamber, the lock piece and the cushion move away from each other, and the throttle passage on the inner periphery of the piece body and communicating with the lock chamber is communicated with the extension-side chamber via the gap between the lock piece and the cushion and the gap between the arms. Since the sliding contact portion is composed of multiple arms and a large gap can be formed between the arms, and the lock piece and the cushion are separated to form a gap, when the lock piece retreats from the lock chamber, the resistance to the flow of liquid moving from the extension side chamber to the lock chamber due to the gap can be made extremely small, and no additional resistance is provided other than the resistance of the throttle passage, so the lock piece can be quickly withdrawn from inside the lock chamber and no resistance is provided to the contraction operation of the shock absorber. Effect of the Invention

[0017] According to the shock absorber of the present invention, it is possible to exert a hydraulic locking function, and the manufacturing process is easy and the manufacturing costs can be reduced. [Brief description of the drawings]

[0018] [Figure 1]FIG. 2 is a cross-sectional view of a shock absorber according to one embodiment. [Diagram 2] Fig. 2(a) is a plan view of the lock piece, Fig. 2(b) is a side view of the lock piece, and Fig. 2(c) is a bottom view of the lock piece. [Diagram 3] Fig. 3(a) is a partially enlarged cross-sectional view of the shock absorber in a state where the lock piece is disposed at a position separated from the lock chamber L. Fig. 3(b) is a partially enlarged cross-sectional view of the shock absorber when the lock piece starts to enter the lock chamber L. Fig. 3(c) is a partially enlarged cross-sectional view of the shock absorber in a state where the lock piece is disposed at a position separated from the lock chamber L. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0019] The shock absorber of the present invention will be described below with reference to the drawings. As shown in Fig. 1, the shock absorber D in one embodiment includes a cylinder 1, a piston rod 2 inserted into the cylinder 1, a piston 3 connected to the piston rod 2 and inserted into the cylinder 1 to divide the cylinder 1 into an extension side chamber R1 and a compression side chamber R2 filled with liquid, a case 8c that is immovable in the axial direction relative to the cylinder 1 and forms a lock chamber L axially facing the piston 3, an annular support 4 attached to the outer periphery of the piston rod 2, a cushion 5 arranged on the outer periphery of the piston rod 2, and a lock piece 6 that is provided on the outer periphery of the piston rod 2 and can enter the lock chamber L. The shock absorber D is interposed between the vehicle body and the wheels of a vehicle (not shown) and generates a damping force during expansion and contraction to suppress vibration of the vehicle body.

[0020] Each part of the shock absorber D will be described in detail below. The cylinder 1 is cylindrical, and as described above, the piston rod 2 and the piston 3 are inserted inside so as to be movable in the vertical direction in FIG. 1, which is the axial direction. The inside of the cylinder 1 is divided by the piston 3 into an expansion-side chamber R1 at the top in FIG. 1 and a compression-side chamber R2 at the bottom in FIG. 1. The expansion-side chamber R1 and the compression-side chamber R2 are filled with a liquid, specifically, hydraulic oil, for example. Note that the liquid may be water, an aqueous solution, or the like, in addition to hydraulic oil.

[0021] The cylinder 1 is accommodated in a bottomed cylindrical outer cylinder 7 arranged on the outer periphery, and a reservoir R is formed in the annular gap between the cylinder 1 and the outer cylinder 7. In this case, the reservoir R stores hydraulic oil as a liquid and gas. The gas filled in the reservoir R is an inert gas such as nitrogen to prevent deterioration of the hydraulic oil, but may be other gas. In this embodiment, the reservoir R is formed between the cylinder 1 and the outer cylinder 7, but the reservoir R may be formed by a tank provided separately from the cylinder 1.

[0022] The piston rod 2 is inserted through the inner circumference of an annular rod guide 8 that fits into the upper end of the cylinder 1 in Figure 1, with its tip side inserted into the cylinder 1, and its base end side, which is the upper end in Figure 1, protruding outward from the cylinder 1.

[0023] The rod guide 8 is annular and includes a small diameter portion 8a that fits into the inner periphery at the upper end of the cylinder 1, a large diameter portion 8b that is connected to the upper end of the small diameter portion 8a in Fig. 1 and fits into the inner periphery of the outer cylinder 7, a cylindrical case 8c that extends downward in Fig. 1 from the outer periphery of the lower end of the small diameter portion 8a, a seal receiving portion 8d that is formed by expanding the inner periphery on the atmosphere side, which is the upper end in Fig. 1, and a pressure relief passage 8e that opens from the seal receiving portion 8d and leads to the lower end of the large diameter portion 8b. A cylindrical bush 9 that comes into sliding contact with the outer periphery of the piston rod 2 is attached to the inner periphery of the rod guide 8.

[0024] The rod guide 8 has a small diameter portion 8a fitted to the inner periphery of the upper end of the cylinder 1 and an outer periphery of a large diameter portion 8b fitted to the inner periphery of the upper end of the outer cylinder 7, thereby closing the upper ends of the cylinder 1 and the outer cylinder 7. The case 8c is cylindrical and hangs down from the outer periphery of the lower end of the small diameter portion 8a, and is formed with an enlarged inner diameter on one side, and opens to the expansion-side chamber R1 to form a lock chamber L facing the expansion-side chamber R1. The inner periphery of the opening at the lower end of the case 8c is provided with a tapered surface 8c1 whose inner diameter becomes larger as it approaches the lower side in FIG.

[0025] The rod guide 8 closes the upper ends of the cylinder 1 and the outer cylinder 7 in FIG. 1, and supports the piston rod 2 inserted into the bush 9 to guide the movement of the piston rod 2 in the axial direction.

[0026] 1, an annular seal member 10 that seals between the piston rod 2 and the outer cylinder 7 is laminated. The seal member 10 includes a core bar 10a formed of an annular plate, an annular inner periphery seal 10b welded to the inner periphery side of the core bar 10a and in sliding contact with the outer periphery of the piston rod 2, an annular outer periphery seal 10c welded to the outer periphery of the lower end of the core bar 10a in FIG. 1 and in close contact with the inner periphery of the outer cylinder 7, and an annular check seal 10d welded to the lower end of the core bar 10a and accommodated in the seal accommodating portion 8d of the rod guide 8 and seated and separated between the inner periphery of the rod guide 8 and the pressure relief passage 8e.

[0027] When the seal member 10 is laminated on the rod guide 8, the lower portion of the inner circumferential seal 10b and the check seal 10d are accommodated in the seal accommodating portion 8d, and the inner circumferential seal 10b comes into sliding contact with the outer periphery of the piston rod 2 while the outer periphery of the outer circumferential seal 10c comes into close contact with the inner periphery of the outer cylinder 7. In this way, the seal member 10 seals between the piston rod 2 and the outer cylinder 7, preventing liquid and gas in the shock absorber D from flowing out of the shock absorber D.

[0028] In addition, when the liquid scraped off by the inner circumferential seal 10b after passing between the piston rod 2 and the bush 9 from the extension-side chamber R1 is stored in the seal accommodating portion 8d and the pressure in the seal accommodating portion 8d increases, the check seal 10d leaves the rod guide 8 and returns the liquid in the seal accommodating portion 8d to the reservoir R via the pressure relief passage 8e. Therefore, the seal accommodating portion 8d is prevented from becoming high pressure, and the inner circumferential seal 10b does not excessively tighten the piston rod 2 due to the pressure in the seal accommodating portion 8d, thereby preventing the smooth movement of the piston rod 2.

[0029] The piston 3 is provided with an extension-side passage 3a and a compression-side passage 3b which communicate between the extension-side chamber R1 and the compression-side chamber R2, an extension-side damping valve 3c which is provided in the extension-side passage 3a and which allows only the flow of hydraulic oil from the extension-side chamber R1 to the compression-side chamber R2 and which provides resistance to the flow of hydraulic oil, and a compression-side check valve 3d which is provided in the compression-side passage 3b and which allows only the flow of hydraulic oil from the compression-side chamber R2 to the extension-side chamber R1.

[0030] 1 of the cylinder 1 is fitted with a valve case 11 placed on the bottom of the outer tube 7. The valve case 11 is provided with a flange 11a on the outer periphery of the lower end in FIG. 1 that fits into the inner periphery of the outer tube 7 and abuts against the lower end of the cylinder 1, and is inserted into the outer tube 7 together with the seal member 10, the rod guide 8, and the cylinder 1, and is fixed inside the outer tube 7 by being clamped between the bottom of the outer tube 7 and a crimped portion 7a formed by crimping the upper end of the outer tube 7 from the outer periphery side.

[0031] In addition, the valve case 11 separates the compression side chamber R2 from the reservoir R, and is equipped with a discharge passage 11b and a suction passage 11c that communicate between the compression side chamber R2 and the reservoir R, a compression side damping valve 11d that is provided in the discharge passage 11b and allows only the flow of hydraulic oil from the compression side chamber R2 to the reservoir R and provides resistance to the flow of hydraulic oil, and an extension side check valve 11e that is provided in the suction passage 11c and allows only the flow of hydraulic oil from the reservoir R to the compression side chamber R2.

[0032] 1 relative to the cylinder 1, the hydraulic oil in the extension-side chamber R1, which is contracted by the movement of the piston 3, passes through the extension-side damping valve 3c and moves to the expansion-side chamber R2, and the pressure in the extension-side chamber R1 rises as the extension-side damping valve 3c applies resistance to the hydraulic oil flow, generating a damping force that impedes the extension operation. Also, during the extension operation of the shock absorber D, the piston rod 2 retreats from the cylinder 1, and the hydraulic oil equivalent to the volume of the piston rod 2 retreating from the cylinder 1 is supplied from the reservoir R to the cylinder 1 via the extension-side check valve 11e.

[0033] In addition, in the shock absorber D, during contraction operation in which the piston 3 moves downward in FIG. 1 relative to the cylinder 1, the hydraulic oil in the compression side chamber R2, which is reduced by the movement of the piston 3, moves through the compression side check valve 3d to the expansion side chamber R1, and since the compression side check valve 3d does not provide much resistance to the flow of hydraulic oil, the pressures in the expansion side chamber R1 and the compression side chamber R2 become approximately equal. During contraction operation of the shock absorber D, the piston rod 2 enters the cylinder 1, and the hydraulic oil in the cylinder 1 becomes excessive by the volume of the piston rod 2 entering the cylinder 1, so the excess hydraulic oil passes through the compression side damping valve 11d and is discharged to the reservoir R. In this way, when the hydraulic oil is discharged from the cylinder 1 to the reservoir R, the pressures in the expansion side chamber R1 and the compression side chamber R2 rise approximately equally because the compression side damping valve 11d provides resistance to the flow of hydraulic oil. Here, since the pressure-receiving area receiving the pressure of the compression-side chamber R2 of the piston 3 is larger than the pressure-receiving area receiving the pressure of the extension-side chamber R1 of the piston 3 by the cross-sectional area of ​​the piston rod 2, the force pushing up the piston 3 increases due to the increase in pressure in the extension-side chamber R1 and the compression-side chamber R2, and the shock absorber D generates a damping force that hinders the contraction operation.

[0034] In this way, when the shock absorber D performs an expansion / contraction operation due to the input of vibration, it generates a damping force that prevents the expansion / contraction. In addition, the reservoir R compensates for the volume of the piston rod 2 moving in and out of the cylinder 1 by exchanging hydraulic oil with the cylinder 1 in an amount equivalent to the volume of the piston rod 2 moving in and out of the cylinder 1 due to the expansion / contraction operation of the shock absorber D. In the shock absorber D of this embodiment, the compensation for the volume of the piston rod 2 moving in and out of the cylinder 1 is performed by exchanging liquid between the reservoir R and the inside of the cylinder 1. However, instead of providing the reservoir R, an air chamber filled with gas by a free piston or a bladder may be provided in the cylinder 1, and the volume of the piston rod 2 moving in and out of the cylinder 1 may be compensated by expanding and contracting the volume of the air chamber. Therefore, the shock absorber D may be set to a single-cylinder type having an air chamber in the cylinder 1, in addition to being set to a double-cylinder type having a reservoir R as in this embodiment. In addition, the shock absorber D may be a double-cylinder type having an intermediate cylinder to form a passage between the cylinder 1 and the outer cylinder 7.

[0035] Next, an annular support 4 is attached to the outer periphery of the piston rod 2 facing the extension-side chamber R1. The support 4 includes a cylindrical portion 4a and a flange-shaped support portion 4b connected to the upper end of the cylindrical portion 4a in FIG. 1, and is attached to the piston rod 2 by spot welding the cylindrical portion 4a to the outer periphery of the piston rod 2 or the like.

[0036] The cushion 5 is annular and made of rubber, urethane foam, or the like, and is fitted to the outer periphery of the piston rod 2 facing the extension-side chamber R1. The cushion 5 is disposed above the support 4 of the piston rod 2 in FIG. 1, and is placed on the side of the support portion 4b of the support 4 opposite the piston in FIG. 1, and the support 4 restricts the movement of the cushion 5 toward the piston side. In this manner, the cushion 5 is disposed on the outer periphery of the piston rod 2 facing the extension-side chamber R1, and the support 4 restricts the movement of the cushion 5 toward the piston side. Since the cushion 5 is annular, it is easy to attach the cushion 5 to the piston rod 2, but it is not necessarily annular and may be attached to the support 4 by welding or the like, as long as the support 4 is disposed on the outer periphery of the piston rod 2 and the movement of the cushion 5 toward the piston side is restricted by the support 4. Furthermore, the support 4 is only required to restrict the movement of the cushion 5 toward the piston side, so the structure of the support 4 can be arbitrarily changed in design, and may be a structure other than that shown in the figure.

[0037] The lock piece 6 is provided on the outer periphery of the piston rod 2, on the opposite side of the cushion 5 to the piston, on the upper side in Fig. 1, so as to be movable in the axial direction. As shown in Figs. 1 and 2, the lock piece 6 is annular and includes a piece main body 6a that is disposed on the outer periphery of the piston rod 2, and a sliding contact portion 6b that extends from the piece main body 6a and is in sliding contact with the outer periphery of the support portion 4b of the support 4. In this embodiment, the lock piece 6 is made of a hard synthetic resin, but the material is not limited thereto.

[0038] The piece body 6a is annular, is disposed on the outer periphery of the piston rod 2 with the piston rod 2 inserted into its inner periphery, and faces the lock chamber L formed in the case 8c in the axial direction. The outer diameter of the piece body 6a is set to a diameter that allows it to fit into the inner periphery of the case 8c, and when the piston rod 2 displaces to the vicinity of the stroke end on the extension side during the extension operation of the shock absorber D in which the piston rod 2 retreats from the cylinder 1, it can enter the lock chamber L formed in the case 8c.

[0039] Furthermore, the axial length of the piece body 6a is longer than the overall length of the case 8c, and when the piece body 6a penetrates to the deepest part of the lock chamber L, it can abut against the lower end surface of the small diameter portion 8a of the rod guide 8. The upper end surface of the piece body 6a on the lock chamber side in FIG. 2 is an uneven surface 6a2 in the circumferential direction, and even if the piece body 6a abuts against the lower end of the small diameter portion 8a of the rod guide 8, the piece body 6a does not come into surface contact with the small diameter portion 8a, and it is possible to prevent the lock piece 6 from sticking to the small diameter portion 8a of the rod guide 8 when the piece body 6a and the rod guide 8 abut against each other.

[0040] The inner diameter of the piece body 6a is larger than the outer diameter of the piston rod 2, and an annular throttle passage P is formed between the piece body 6a and the piston rod 2. In addition, since a clearance corresponding to the throttle passage P is provided between the piece body 6a and the piston rod 2, the piece body 6a can move radially relative to the piston rod 2 by the clearance.

[0041] In addition, the outer diameter of the piece body 6a is a diameter that can be fitted into the inner circumference of the case 8c, the inner diameter of the piece body 6a is larger than the outer diameter of the piston rod 2, and the piece body 6a is allowed to move radially relative to the piston rod 2 by the clearance between the inner circumference of the piece body 6a and the piston rod 2, so that even if the piece body 6a is eccentric with respect to the case 8c, the piece body 6a can enter the lock chamber L. Note that, if the piece body 6a can be inserted into the case 8c even when it is in sliding contact with the outer circumference of the piston rod 2, the throttle passage P may be formed by a groove provided along the axial direction on the outer circumference of the piece body 6a or a hole that opens from the upper end of the piece body 6a and communicates with the lower end, or the throttle passage P may be formed by a groove provided along the axial direction on the inner circumference of the case 8c or a gap between the case 8c and the piece body 6a that is formed by making the inner diameter of the case 8c larger than the outer diameter of the piece body 6a.

[0042] In this embodiment, the sliding contact portion 6b has a plurality of arms 6b1 extending downward from a portion extending from the outer periphery of the lower end of the piece body 6a to the lower end in Fig. 2. The lock piece 6 also has claws 6c protruding inward from the lower end in Fig. 2, which is the tip of each arm 6b1 constituting the sliding contact portion 6b.

[0043] The five arms 6b1 are provided on the piece body 6a at equal intervals in the circumferential direction of the piece body 6a. The arms 6b1 extend downward from the piece body 6a in parallel to each other.

[0044] Next, the diameter of an inscribed circle inscribed on the inner surface of each arm 6b1 facing the piston rod side is equal to or slightly smaller than the outer diameter of the support portion 4b of the support 4, and is larger than the outer diameter of the cushion 5. Therefore, when the lock piece 6 is assembled to the outer periphery of the piston rod 2, the lock piece 6 can bring the inner surface of each arm 6b1 into sliding contact with the outer periphery of the support portion 4b of the support 4. Also, the length from the upper end of the piece main body 6a in FIG. 1 to the upper end of the arm 6b1 in FIG. 1 is longer than the length from the lower end in FIG. 1, which is the tip of the case 8c, to the small diameter portion 8a, which is the bottom of the lock chamber L, and the piece main body 6a can enter the lock chamber L until it abuts against the small diameter portion 8a of the rod guide 8. In shock absorber D of this embodiment, even when piece main body 6a abuts against small diameter portion 8a, case 8c does not interfere with arm 6b1, and no load is applied to arm 6b1 from rod guide 8. However, it is also possible to avoid contact between piece main body 6a and small diameter portion 8a by abutting the base of arm 6b1 against case 8c.

[0045] The claws 6c are provided at the lower end in FIG. 2, which is the tip of the arm 6b1, and protrude radially toward the inner peripheral surface of the arm 6b1. The diameter of a circle inscribed with the tips of the claws 6c is smaller than the outer diameter of the support part 4b of the support 4. The claws 6c also have a tapered surface 6c1 at the tip side of the lower end, and are shaped to taper toward the tip. Therefore, when the lock piece 6 is inserted into the piston rod 2 from the upper end side in FIG. 1 during assembly of the lock piece 6, the outer periphery of the upper end of the support part 4b of the support 4 in FIG. 1 eventually comes into contact with the tapered surface 6c1 of each claw 6c. When the lock piece 6 is further inserted into the lock piece 6 of the piston rod 2, the support part 4b of the support 4 is pressed against the tapered surface 6c1, so that the arm 6b1 is bent and the claws 6c are pushed aside radially. Then, when the support portion 4b passes over the claw 6c, the bent arm 6b1 returns to its original state by a restoring force and abuts against the outer peripheral surface of the support portion 4b, and the tip of the claw 6c faces the lower surface of the support portion 4b, which is the piston side surface of the support portion 4b, in FIG. 1. When the lock piece 6 is disposed on the outer periphery of the piston rod 2 and assembled to the support portion 4b of the support 4 in this manner, the inner surface of the arm 6b1 in the sliding portion 6b slides against the outer peripheral surface of the support portion 4b, and the claw 6c faces the piston side surface of the support portion 4b, so that the lock piece 6 can move in a direction away from the support 4 until the claw 6c abuts against the piston side surface of the support portion 4b without falling off the support 4. In this manner, the claw 6c constitutes a restricting portion that prevents the lock piece 6 from coming off the support 4, and while allowing the lock piece 6 to move in the axial direction relative to the support 4, it prevents the lock piece 6 from coming off the support 4 when the lock piece 6 reaches the movement limit in the direction of coming off the support 4.

[0046] 1, the length X from the lower end of the piece main body 6a in FIG. 3 to the claw 6c on the arm 6b1 is longer than the length Y from the lower end of the support portion 4b of the support 4 in FIG. 1 to the upper end of the cushion 5, and when the claw 6c is in contact with the support portion 4b, a gap is generated between the lower end of the piece main body 6a and the upper end of the cushion 5 placed on the support portion 4b. Therefore, the lock piece 6 is capable of reciprocating in the axial direction relative to the piston rod 2 within the range from when the claw 6c is in contact with the support portion 4b to when the piece main body 6a is in contact with the cushion 5, ignoring the compressive deformation of the cushion 5.

[0047] In addition, a plurality of grooves 6a1 are provided from the inner periphery to the outer periphery at the piston side end, which is the lower end of the piece body 6a in Fig. 2. The grooves 6a1 are provided at positions that avoid the arms 6b1, so that even if the cushion 5 abuts against the piece body 6a, the throttle passage P is allowed to communicate with the outside of the lock piece 6 via the grooves 6a1.

[0048] The shock absorber D is constructed as described above, and its operation will be described below. As described above, when the shock absorber D performs an expansion / contraction operation, a damping force is generated, but during an expansion operation in which the piston 3 moves upward relative to the cylinder 1 in FIG. 1, the piston rod 2 moves upward relative to the cylinder 1, and the cushion 5 placed on the support 4 and the lock piece 6 attached to the outer periphery of the support part 4b of the support 4 also move upward and approach the case 8c in the rod guide 8.

[0049] As shown in FIG. 3(b), when the piece body 6a of the lock piece 6 starts to be inserted into the lock chamber L in the case 8c, the piece body 6a fits into the case 8c to communicate the lock chamber L and the expansion-side chamber R1 only through the throttle passage P. When the piece body 6a is inserted into the case 8c, even if the piece body 6a is eccentric with respect to the case 8c, when the outer periphery of the upper end of the piece body 6a in FIG. 1 abuts against the tapered surface 8c1 provided on the inner periphery of the lower end of the case 8c, the piece body 6a can easily enter the case 8c while moving in the radial direction following the tapered surface 8c1. In this way, since the annular throttle passage P is provided between the piece body 6a and the piston rod 2, the lock piece 6 can move in the radial direction with respect to the piston rod 2, so that the piece body 6a can easily enter the lock chamber L even if it is eccentric with respect to the case 8c.

[0050] When the piston rod 2 moves further upward relative to the cylinder 1 with the piece body 6a inserted in the lock chamber L, the lock chamber L is compressed by the lock piece 6, and the liquid in the lock chamber L passes through the throttle passage P between the piece body 6a and the piston rod 2, between the piece body 6a and the cushion 5, and between the arms 6b1, 6b1 and moves to the extension-side chamber R1. The throttle passage P provides resistance to such a flow of liquid, so that the pressure in the lock chamber L rises and pushes down the lock piece 6, bringing the piece body 6a into contact with the cushion 5. Even when the cushion 5 comes into contact with the piece body 6a, the groove 6a1 is not blocked, so communication between the lock chamber L and the extension-side chamber R1 is not interrupted.

[0051] Then, as the pressure inside the lock chamber L rises, the piece main body 6a comes into contact with the cushion 5, and the load caused by the pressure rise in the lock chamber L acts on the support 4 and the piston rod 2, preventing the piston rod 2 from moving upward relative to the cylinder 1. Therefore, in the shock absorber D configured in this manner, when the lock piece 6 enters the lock chamber L and the shock absorber D attempts to extend further, a hydraulic lock function is exerted that prevents the shock absorber D from extending due to the load caused by the pressure rise in the lock chamber L described above.

[0052] Furthermore, when the piston rod 2 continues to move upward relative to the cylinder 1 after the piece body 6a is inserted into the lock chamber L, the upper end of the piece body 6a eventually comes into contact with the lower end of the small diameter portion 8a of the rod guide 8, which is the bottom of the lock chamber L, as shown in FIG. 3(c), and the upward movement of the lock piece 6 relative to the case 8c is restricted, and the lock chamber L is fully compressed. When the shock absorber D tries to extend further, the upward movement of the lock piece 6 is restricted, so the cushion 5 is compressed and exerts a resilient force that prevents the upward movement of the piston rod 2 relative to the cylinder 1. In this way, when the lock piece 6 fully compresses the lock chamber L, the shock absorber D generates a load that prevents extension due to the resilient force caused by the compression of the cushion 5. The resilient force due to the compression of the cushion 5 is larger than the load due to the hydraulic lock function, and the shock absorber D generates a large force when it reaches the fully extended state and prevents the extension operation.

[0053] After the lock piece 6 enters the lock chamber L, when the shock absorber D contracts and the piston rod 2 moves downward relative to the cylinder 1, the piston rod 2 also moves downward relative to the lock piece 6, but when the claw 6c of the lock piece 6 abuts against the piston side end of the support part 4b of the support 4, the lock piece 6 also moves downward together with the piston rod 2 and exits from the lock chamber L. Even if the lock piece 6 enters the lock chamber L, the lock chamber L is connected to the extension-side chamber R1 via the throttle passage P, so that liquid is supplied from the extension-side chamber R1 to the lock chamber L when the lock piece 6 exits. Therefore, excessive resistance is not applied to the downward movement of the piston rod 2 when the lock piece 6 exits from the lock chamber L.

[0054] In this way, when the shock absorber D undergoes an extension operation and extends near the stroke end, first the pressure in the lock chamber L is increased to prevent the extension operation by the load caused by the hydraulic lock function, and then the extension operation is prevented by the elastic force of the cushion 5 which is in the fully extended state.

[0055] As described above, the shock absorber D of this embodiment includes a cylinder 1, a piston rod 2 inserted into the cylinder 1 so as to be axially movably, a piston 3 connected to the piston rod 2 and movably inserted into the cylinder 1 to divide the cylinder 1 into an extension-side chamber R1 filled with liquid and a compression-side chamber R2, a case 8c that is immovable in the axial direction relative to the cylinder 1 and forms a lock chamber L axially opposed to the piston 3, a support 4 attached to the outer periphery of the piston rod 2 facing the extension-side chamber R1, a cushion 5 that is arranged on the outer periphery of the piston rod 2 facing the extension-side chamber R1 and whose movement toward the piston side is restricted by the support 4, and a lock piece 6 that is provided on the outer periphery of the piston rod 2 on the opposite piston side of the cushion 5 so as to be axially movably and can enter the lock chamber L.

[0056] In the shock absorber D configured in this manner, a case 8c that is immovable in the axial direction is provided relative to the cylinder 1, and a lock piece 6 is provided on the piston rod 2. This allows the lock piece 6 to enter the lock chamber L near the stroke end during extension operation, thereby exerting a hydraulic locking function and suppressing the extension of the shock absorber D. When the extension progresses to the maximum extension stage, a large load is generated by the compression of the cushion 5, which stops the extension of the shock absorber D and reduces the impact at the time of maximum extension.

[0057] Therefore, when shock absorber D is driven on good roads, even if the damping force is reduced, it exhibits a hydraulic locking function that does not generate elastic rebound near the stroke end, improving ride comfort when the vehicle body pitches during braking, while when fully extended, it exhibits a large force through cushion 5 to suppress rebound, making it ideal for use in recent light cars and compact cars.

[0058] According to the shock absorber D configured as above, compared to a general shock absorber that has the support 4 and the cushion 5 and absorbs the impact at the maximum extension only by compressing the cushion 5, the addition of the case 8c and the lock piece 6 allows the shock absorber D to exhibit a hydraulic lock function at the time of extension, so there is no need to provide a tapered enlarged diameter portion at the end of the cylinder or to add many parts such as an elastic ring, a segment, or a spring as in the conventional shock absorber. Therefore, according to the shock absorber D of this embodiment, the machining for enlarging the diameter of the cylinder and the installation of many parts on the outer periphery of the piston rod 2, which were necessary in the conventional shock absorber, are not necessary, so the machining cost can be reduced and the number of parts can be reduced. As described above, according to the shock absorber D of this embodiment, the shock absorber D can exhibit a hydraulic lock function and can be easily manufactured, thereby reducing the manufacturing cost.

[0059] Moreover, the lock piece 6 in the shock absorber D of this embodiment is annular and is disposed on the outer periphery of the piston rod 2 to form an annular throttle passage P between it and the piston rod 2, and is equipped with a piece body 6a that can enter the lock chamber L. According to the shock absorber D configured in this manner, when the piece body 6a enters the lock chamber L, a load of a magnitude corresponding to the resistance of the throttle passage P can be generated, and the load can be adjusted by setting the flow path area of ​​the throttle passage P, and the piece body 6a can easily move in the vertical direction relative to the cushion 5 due to the clearance between the inner periphery of the piece body 6a and the piston rod 2, so that the cushion 5 is smoothly compressed after the lock piece 6 enters the lock chamber L.

[0060] Furthermore, the lock piece 6 in the shock absorber D of this embodiment has a sliding contact portion 6b that comes into sliding contact with the outer periphery of the support 4. According to the shock absorber D configured in this manner, the lock piece 6 can be centered by the support 4 and positioned in the radial direction relative to the case 8c and the cushion 5, making it easy to insert the lock piece 6 into the case 8c.

[0061] In the shock absorber D of this embodiment, the piece body 6a of the lock piece 6 has a circumferentially uneven surface 6a2 on the surface facing the case 8c. According to the shock absorber D configured in this manner, the upper surface of the piece body 6a facing the case in FIG. 1 is the uneven surface 6a2, so even if the piece body 6a penetrates deeply into the lock chamber L and abuts against the lower surface of the small diameter portion 8a of the rod guide 8, which is the bottom surface of the lock chamber L, the entire upper surface of the piece body 6a does not abut against the small diameter portion 8a, so that the piece body 6a is prevented from sticking to the bottom surface of the lock chamber L. Therefore, when the shock absorber D is fully extended and the piece body 6a abuts against the bottom surface of the lock chamber L and then performs a contracting operation, the piece body 6a can quickly retreat from within the lock chamber L, and does not provide resistance to the contracting operation of the shock absorber D.

[0062] In the shock absorber D of this embodiment, the lock piece 6 is provided at the sliding contact portion 6b with a claw (regulating portion) 6c that prevents the lock piece 6 from coming off the support 4. According to the shock absorber D configured in this manner, after the lock piece 6 enters the lock chamber L during the extension operation to exert the hydraulic lock function, when the direction of extension and contraction is switched to perform the contraction operation, the claw (regulating portion) 6c of the lock piece 6 is caught on the piston side surface of the support 4, so that the lock piece 6 moves downward in FIG. 1 with the piston rod 2 relative to the case 8c. Therefore, the lock piece 6 does not remain in the lock chamber L, and the hydraulic lock function can be stably exerted even if the extension and contraction are repeated. Note that the restricting portion only needs to prevent the lock piece 6 from coming off the support 4 while allowing the lock piece 6 to move in the axial direction by a certain distance relative to the support 4 so that the lock piece 6 that entered the lock chamber L when the piston rod 2 moves downward in FIG. 1 can follow the movement of the piston rod 2 toward the contraction side so as not to be left behind in the lock chamber L. Therefore, the regulating portion may be composed of a groove along the axial direction provided on the outer periphery of the piston rod 2 and a pin provided on the sliding portion 6b and inserted into the groove, or may be composed of a long hole along the axial direction provided on the sliding portion 6b and a pin provided on the support 4 or the piston rod 2 and inserted into the long hole, in addition to the claw 6c provided on the sliding portion 6b.

[0063] Furthermore, in the shock absorber D of this embodiment, when the lock piece 6 is farthest from the cushion 5 in the axial direction, a gap is formed between the lock piece 6 and the cushion 5, and the sliding contact portion 6b is composed of a plurality of arms 6b1 extending at intervals in the circumferential direction relative to the piece main body 6a. In the shock absorber D configured in this manner, when the lock piece 6 enters the lock chamber L during the extension operation to exert the hydraulic locking function, and then the direction of extension and contraction is switched to perform the contraction operation and the lock piece 6 leaves the lock chamber L, the lock piece 6 and the cushion 5 are separated, and the throttle passage P which is on the inner periphery of the piece main body 6a and communicates with the lock chamber L is communicated with the extension-side chamber R1 via the gap between the lock piece 6 and the cushion 5 and the gap between the arms 6b1, 6b1. Since the sliding portion 6b is composed of multiple arms 6b1, a large gap can be formed between the arms 6b1, 6b1, and the lock piece 6 and the cushion 5 are separated to form a gap. Therefore, when the lock piece 6 retreats from the lock chamber L, the resistance to the flow of liquid moving from the extension-side chamber R1 to the lock chamber L due to the gap can be made extremely small, and no additional resistance is provided other than the resistance of the throttle passage P. Therefore, the lock piece 6 can be quickly retreated from within the lock chamber L, and no resistance is provided to the contraction operation of the shock absorber D.

[0064] In addition, since the sliding portion 6b is composed of multiple arms 6b1, as described above, when the lock piece 6 retreats from the lock chamber L, a gap can be formed between the arms 6b1, 6b1 that allows the passage of liquid from the extension side chamber R1 to the lock chamber L without significant resistance.

[0065] As described above, when the sliding contact portion 6b has a plurality of arms 6b1, the various advantages described above can be obtained, but the sliding contact portion 6b may be formed of a cylinder having a hole or a notch on the side that communicates the expansion-side chamber R1 with the throttle passage P. When the sliding contact portion 6b is cylindrical in this way, the claws 6c may be provided annularly at the lower end of the cylinder or may be provided intermittently in the circumferential direction.

[0066] Furthermore, in shock absorber D of this embodiment, case 8c which forms lock chamber L is provided on rod guide 8, so that the number of parts can be reduced compared to the case where another case is provided independently, thereby enabling further reduction in manufacturing costs; however, the case may be a separate part from rod guide 8, and may be fixed to cylinder 1 or outer tube 7 independently of rod guide 8, or may be attached to rod guide 8 as a separate part.

[0067] The lock piece 6 may be integrated with the cushion 5 by adhesion, fusion, or the like, in which case the cushion 5 may be attached to the support 4 by gripping the outer periphery of the support 4, for example. The lock chamber L is formed inside the case 8c of the rod guide 8, but an annular case may be provided on the inner periphery of the rod guide 8 to form the lock chamber L between the case and the cylinder 1. When the lock chamber L is provided on the outer periphery of the rod guide 8 in this manner, it is only necessary to provide an annular piece main body facing the lock chamber L so that the lock piece 6 can enter the lock chamber L.

[0068] Although the preferred embodiment of the present invention has been described in detail above, modifications, variations and changes can be made without departing from the scope of the appended claims. [Explanation of symbols]

[0069] Reference Signs List 1 cylinder, 2 piston rod, 3 piston, 4 support, 5 cushion, 6 lock piece, 6a piece body, 6a2 uneven surface, 6b sliding contact portion, 6b1 arm, 6c claw (regulating portion), 8c case, D shock absorber, P return passage, R reservoir, R1 expansion side chamber, R2 compression side chamber

Claims

1. A cylinder; A piston rod is inserted into the cylinder so as to be movable in the axial direction; a piston connected to the piston rod and movably inserted into the cylinder to divide the inside of the cylinder into an extension-side chamber and a compression-side chamber filled with liquid; a case that is immovable in the axial direction relative to the cylinder and that defines a lock chamber that is open toward the piston; A support is attached to an outer periphery of the piston rod facing the extension-side chamber; a cushion that is disposed on an outer periphery of the piston rod facing the extension-side chamber and whose movement toward the piston side is restricted by the support; a lock piece that is disposed on the outer periphery of the piston rod on the side opposite to the piston of the cushion and is provided movably in the axial direction and capable of entering the lock chamber; A shock absorber characterized by:

2. The lock piece is a piece body that is annular and disposed on the outer periphery of the piston rod to form an annular throttle passage between the piston rod and the piece body, and that is capable of entering the lock chamber; 2. The shock absorber according to claim 1 .

3. The lock piece is A sliding contact portion that is in sliding contact with the support 2. The shock absorber according to claim 1 .

4. The lock piece has a piece body that can enter the lock chamber and has an uneven surface on a surface facing the case.

2. The shock absorber according to claim 1 .

5. When the lock piece moves away from the cushion in the axial direction, a gap communicating with the throttle passage is formed between the lock piece and the cushion, The sliding contact portion is composed of a plurality of arms extending at intervals in the circumferential direction relative to the piece body.

3. The shock absorber according to claim 2.

6. The lock piece is The sliding contact portion has a restricting portion that prevents the sliding contact portion from coming off the support.

4. The shock absorber according to claim 3.

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