Shock absorber

Abstract

To provide a shock absorber capable of securing smooth axial movement of a movable spring bearing, and realizing a smooth operation.SOLUTION: A shock absorber D comprises: a shock absorber body 1 having a cylinder 2 and a rod 3 movably inserted in the cylinder 2, and generating an attenuation force at the time of shrinkage; a cylinder side spring bearing 4 mounted on an outer periphery of the cylinder 2; a rod side spring bearing 5 mounted on the rod 3; a movable spring bearing 6 arranged on the outer periphery of the cylinder 2 and movable to the cylinder 2 in an axial direction; a first coil spring 7 interposed between the cylinder side spring bearing 4 and the movable spring bearing 6; and a second coil spring 8 interposed between the rod side spring bearing 5 and the movable spring bearing 6. The movable spring bearing 6 comprises: a seat part 6a nipped between the first coil spring 7 and the second coil spring 8; and a protection cylinder 6b having a cylindrical shape and extending from the seat part 6a to the rod side, and covering the outer periphery of the cylinder. A tip of the protection cylinder 6b is projected to the rod side than a rod side end of the cylinder 2 when the shock absorber body extends the most.SELECTED DRAWING: Figure 1

Description

[Technical field]

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

[0002] Shock absorbers used in saddle-type vehicles such as motorcycles and all-terrain vehicles include, for example, a shock absorber body having a cylinder, a rod that is movably inserted into the cylinder, and a piston that is connected to the rod and inserted slidably into the cylinder, and a suspension spring that is interposed between the rod and the cylinder.

[0003] In shock absorbers that have such an integrated suspension spring, the suspension spring is sometimes composed of two coil springs with different spring constants, and one of the coil springs is set to its tight length before the shock absorber body reaches the stroke end on the contraction side.

[0004] More specifically, the shock absorber comprises a rod-side spring bearing fixed to the tip of the rod, a cylinder-side spring bearing fixed near the lower end of the cylinder, and an annular movable spring bearing that is slidably attached to the outer periphery of the cylinder between the rod-side spring bearing and the cylinder-side spring bearing, and coil springs are interposed between the rod-side spring bearing and the movable spring bearing, and between the cylinder-side spring bearing and the movable spring bearing, respectively, to form a suspension spring.

[0005] In a shock absorber configured in this manner, when the shock absorber body contracts and one of the two coil springs reaches its tight length, only the other coil spring exerts a spring force against any further stroke of the shock absorber body toward the contraction side, enabling the suspension spring to exert a spring force appropriate to the expansion / contraction displacement of the shock absorber body (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0006] [Patent Document 1] JP 2010-065719 A Summary of the Invention [Problem to be solved by the invention]

[0007] In conventional shock absorbers, in order to change the spring constant of the suspension spring midway through the stroke of the shock absorber body, the suspension spring is composed of two coil springs, and the movable spring holder between the coil springs is in sliding contact with the outer periphery of a cylinder, which acts as a guide to move the spring in the axial direction, with the coil springs arranged on the outer periphery of the cylinder over almost the entire length of the cylinder.

[0008] Therefore, in conventional shock absorbers, the cylinder and the suspension spring may interfere with each other when the shock absorber body expands and contracts, or flying stones may strike the cylinder through the filaments of the coil spring while the saddle-type vehicle is traveling, which may damage the sliding surface of the movable spring bearing on the outer periphery of the cylinder. Also, in conventional shock absorbers, the axial length of the movable spring bearing is short, and the length of engagement of the movable spring bearing with the cylinder is short, so that the movable spring bearing may tilt with respect to the cylinder. If the sliding surface of the movable spring bearing of the cylinder is damaged in this way, the smooth axial movement of the movable spring bearing with respect to the cylinder is impaired, and if the movable spring bearing tilts with respect to the cylinder, stick-slip occurs between the movable spring bearing and the cylinder, which impairs the smooth axial movement of the movable spring bearing with respect to the cylinder.

[0009] SUMMARY OF THE PRESENT EMBODIMENTS An object of the present invention is to provide a shock absorber that can ensure smooth axial movement of a movable spring bearing and achieve smooth operation. [Means for solving the problem]

[0010] In order to solve the above problems, the shock absorber of the present invention comprises a shock absorber body having a cylinder and a rod inserted into the cylinder so as to be axially movable, and generating a damping force when extended or contracted, a cylinder side spring bearing attached to the outer periphery of the cylinder, a rod side spring bearing attached to the rod, a movable spring bearing arranged on the outer periphery of the cylinder and movable in the axial direction relative to the cylinder, a first coil spring interposed between the cylinder side spring bearing and the movable spring bearing, and a second coil spring interposed between the rod side spring bearing and the movable spring bearing, wherein the movable spring bearing has a seat portion sandwiched between the first coil spring and the second coil spring, and a cylindrical protective tube extending from the seat portion toward the rod side and covering the outer periphery of the cylinder, and wherein when the shock absorber body is fully extended, the tip of the protective tube protrudes toward the rod side beyond the rod side end of the cylinder.

[0011] In a shock absorber configured in this manner, even when the shock absorber body expands or contracts, the movable spring bearing is always present between the cylinder and the second coil spring, thereby preventing interference between the cylinder and the second coil spring, and also preventing flying stones that fly in while the saddle-type vehicle is traveling from reaching the cylinder even if they pass between the wires of the second coil spring by the protective tube.

[0012] In addition, the protective tube and the rod side spring bearing in the shock absorber may always face each other with a gap in the axial direction regardless of the expansion / contraction state of the shock absorber body. With a shock absorber configured in this manner, the protective tube can protect the outer periphery of the cylinder while avoiding interference between the protective tube and the rod side spring bearing, and can prevent the generation of impact noise due to a collision between the protective tube and the rod side spring bearing when the shock absorber body is fully contracted, without causing discomfort to the passenger of the saddle-type vehicle.

[0013] Furthermore, the movable spring bearing in the shock absorber may have a communication portion that communicates the inside and outside of the protective tube. With this type of shock absorber, it is possible to prevent water or dust from accumulating between the protective tube and the cylinder, which would hinder smooth movement of the movable spring bearing relative to the cylinder.

[0014] Furthermore, the movable spring bearing in the shock absorber may be formed of a part divided into two in the radial direction. With a shock absorber configured in this manner, each divided piece can be easily manufactured by injection molding using a mold of a simple shape, reducing manufacturing costs and enabling the restriction of radial movement of the second coil spring over the entire length of the protective tube.

[0015] Furthermore, the movable spring bearing in the shock absorber may have a protective cylinder that is detachable from the seat portion. According to the shock absorber configured in this manner, when a plurality of shock absorbers with different specifications having different cylinder lengths are manufactured, there is an advantage that the movable spring bearing can be easily manufactured. Effect of the Invention

[0016] According to the shock absorber of the present invention, smooth axial movement of the movable spring bearing can be ensured, and smooth operation can be achieved. [Brief description of the drawings]

[0017] [Figure 1] FIG. 1 is a side view of a shock absorber according to one embodiment. [Diagram 2] Fig. 2(a) is a cross-sectional view of a modified example of the movable spring bearing, and Fig. 2(b) is a bottom view of the modified example of the movable spring bearing. [Diagram 3] FIG. 3 is a sectional view of another modified example of the movable spring bearing. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0018] The present invention will be described based on the embodiment shown in the drawings. As shown in Fig. 1, a shock absorber D in one embodiment includes a shock absorber body 1 having a cylinder 2 and a rod 3 inserted into the cylinder 2 so as to be movable in the axial direction, and generating a damping force when expanding or contracting, a cylinder side spring bearing 4 attached to the outer periphery of the cylinder 2, a rod side spring bearing 5 attached to the rod 3, a movable spring bearing 6 disposed on the outer periphery of the cylinder 2 and movable in the axial direction relative to the cylinder 2, a first coil spring 7 interposed between the cylinder side spring bearing 4 and the movable spring bearing 6, and a second coil spring 8 interposed between the rod side spring bearing 5 and the movable spring bearing 6. Although not shown, the shock absorber D is interposed between the body and the wheel of a motorcycle, an all-terrain vehicle, or other saddle-type vehicle, for example, and generates a damping force when expanding or contracting to suppress vibration of the body.

[0019] Hereinafter, each part of the shock absorber D will be described. The shock absorber body 1 includes a cylinder 2, a rod 3 inserted into the cylinder 2 so as to be movable in the axial direction, and, for example, although not shown, a piston connected to the rod 3 and inserted into the cylinder 2 so as to be movable in the axial direction, which divides the inside of the cylinder 2 into an extension-side chamber and a compression-side chamber filled with hydraulic oil, and a damping passage communicating with the extension-side chamber and the compression-side chamber, and generates a damping force that impedes expansion and contraction by providing resistance through the damping passage to the flow of hydraulic oil that travels between the extension-side chamber and the compression-side chamber during expansion and contraction.

[0020] The shock absorber body 1 includes a head member 11 including a cap 11a that closes the upper end of the cylinder 2 in FIG. 1, and a tank 11b that is connected to the cap 11a and is disposed on the side of the cylinder 2 to form a reservoir for storing gas and hydraulic oil therein, and the volume of the rod 3 that moves in and out of the cylinder 2 as it expands and contracts is compensated for by the air chamber or the tank 11b. The reservoir may be formed in the cylinder 2 instead of being formed by the tank 11b. In addition, when the reservoir is provided, a variable damping valve capable of adjusting the damping force may be provided in the passage connecting the compression side chamber and the reservoir. The shock absorber body 1 may compensate for the volume of the rod 3 that moves in and out of the cylinder 2 as it expands and contracts by an air chamber provided in the cylinder 2 instead of the reservoir. The cylinder 2 includes a screw portion 2a on the outer periphery within a predetermined range from the lower end of the cap 11a in FIG. 1.

[0021] The rod 3 passes through the inner circumference of an annular rod guide (not shown) provided at the lower end of the cylinder 2 in FIG. 1, and has its upper end inserted into the cylinder 2 and its lower end protruding outside the cylinder 2.

[0022] An eye-shaped bracket 12 that enables attachment to a link connected to a swing arm that holds the rear wheel of a saddle-type vehicle (not shown) is attached to the lower end of the rod 3. The rod-side spring bearing 5 is attached to the rod 3 via the eye-shaped bracket 12 and disposed on the outer periphery of the lower end of the rod 3, and a cylindrical cushion 13 made of urethane rubber that fits onto the outer periphery of the rod 3 is layered above the rod-side spring bearing 5 in FIG.

[0023] The rod-side spring bearing 5 is annular and includes a concave fitting portion 5a that fits into the upper end of the eye-shaped bracket 12 in FIG. 1, and a flange-shaped spring seat 5b provided on the outer periphery of the fitting portion 5a.

[0024] The cylinder side spring bearing 4 is provided with an annular nut 4a that is screwed to a screw portion 2a provided on the outer periphery of the upper end of the cylinder 2 in FIG. 1, and an annular spring sheet 4b with an L-shaped cross section that is laminated below the nut 4a. The nut 4a has alternating projections and recesses (not shown) along the circumferential direction on its outer periphery, and the fixed position of the nut 4a relative to the cylinder 2 can be changed by rotating the nut 4a relative to the cylinder 2 using a tool that grips the projections and recesses on the outer periphery of the nut 4a. Therefore, by rotating the nut 4a relative to the cylinder 2, the position of the spring sheet 4b in the cylinder side spring bearing 4 relative to the cylinder 2 can be adjusted in the vertical direction in FIG. 1.

[0025] The movable spring bearing 6 is made of synthetic resin and includes an annular seat portion 6a, a cylindrical protective tube 6b extending from the inner periphery of the seat portion 6a toward the rod side and covering the outer periphery of the cylinder 2, and an annular fitting tube 6c extending from the inner periphery of the seat portion 6a toward the cap side. Note that the movable spring bearing 6 may be made of a material other than synthetic resin as long as it has excellent sliding properties and is strong enough to receive the load from the first coil spring 7 and the second coil spring 8.

[0026] The seat portion 6a is annular and faces the spring seat 4b of the cylinder side spring bearing 4 and the spring seat 5b of the rod side spring bearing 5 in the axial direction. The protective tube 6b extends downward from the inner circumference of the rod side end, which is the lower end of the seat portion 6a in FIG. 1, and has a hole 6b1 as a communication portion communicating the inside and outside near the lower end in FIG. 1, and a plurality of grooves 6b2 along the axial direction provided at intervals in the circumferential direction on the outer circumference, and the inner peripheral surface is in sliding contact with the outer circumference of the cylinder 2, lower in FIG. 1 than the screw portion 2a. The fitting tube 6c extends upward from the inner circumference of the cap side end, which is the upper end of the seat portion 6a in FIG. 1, of the seat portion 6a, and the inner peripheral surface is in sliding contact with the outer circumference of the cylinder 2, lower in FIG. 1 than the screw portion 2a. The inner diameters of the seat portion 6a, the protective tube 6b, and the fitting tube 6c are all equal and have a diameter that allows the movable spring bearing 6 to slide against the outer periphery of the cylinder 2, and the movable spring bearing 6 can move in the vertical direction in FIG. 1, which is the axial direction, relative to the cylinder 2, using the cylinder 2 as a guide by sliding against the outer periphery of the cylinder 2. The movable spring bearing 6 is also lightened by being provided with a plurality of grooves 6b2 formed along the axial direction on the outer periphery of the protective tube 6b, and the hole 6b1 allows water that has entered between the cylinder 2 and the movable spring bearing 6 to be discharged from between the cylinder 2 and the movable spring bearing 6 to the outside of the protective tube 6b. In this embodiment, the hole 6b1 is an elongated hole along the axial direction of the protective tube 6b, but the shape of the hole 6b1 is not limited thereto. In this embodiment, the communication part is a hole 6b1 that communicates between the inside and outside of the protective tube 6b, but since the communication part only needs to communicate between the inside and outside of the protective tube 6b and be able to discharge water to the outside of the protective tube 6b, it may be a notch that opens at the bottom end of the protective tube 6b or a groove that is provided on the inner circumference of the protective tube 6b and opens at the bottom end of the protective tube 6b, in addition to the hole 6b1. Note that the hole 6b1 and the groove 6b2 do not have to be provided in the movable spring bearing 6.

[0027] The first coil spring 7 is interposed between the spring seat 4b of the cylinder side spring bearing 4 and the upper end of the seat portion 6a of the movable spring bearing 6 in Fig. 1. The inner periphery of the lower end of the first coil spring 7 is fitted into the outer periphery of the fitting tube 6c of the movable spring bearing 6, so that radial movement is restricted and interference with the cylinder 2 is prevented.

[0028] 1 of the seat portion 6a of the movable spring bearing 6. The inner periphery of the lower end of the second coil spring 8 is fitted into the outer periphery of the fitting portion 5a of the rod side spring bearing 5, and a protective tube 6b is inserted into the second coil spring 8, so that radial movement of the second coil spring 8 with respect to the cylinder 2 is restricted.

[0029] The first coil spring 7 and the second coil spring 8 are interposed between the cylinder side spring bearing 4 and the rod side spring bearing 5 in a mutually compressed state, and bias the shock absorber body 1 in a direction that expands it.

[0030] When the shock absorber body 1 expands or contracts, the movable spring bearing 6 can move in the axial direction relative to the cylinder 2, so the first coil spring 7 and the second coil spring 8 also expand or contract so that their elastic forces are balanced. The natural length of the first coil spring 7 is shorter than the natural length of the second coil spring 8, so that when the shock absorber body 1 contracts from the most extended state in which the rod 3 projects to the maximum from the cylinder 2, the first coil spring 7, which has a shorter natural length, contracts to the maximum and reaches a tight length, becoming unable to contract any further, before the shock absorber body 1 reaches the most contracted state in which the rod 3 penetrates to the maximum inside the cylinder 2.

[0031] Therefore, in the shock absorber D, while the shock absorber main body 1 contracts from its maximum extended state until the first coil spring 7 reaches its tight length, the first coil spring 7 and the second coil spring 8 are capable of contracting, and thus exert an elastic force proportional to the combined spring constant of the first coil spring 7 and the second coil spring 8, urging the shock absorber main body 1 toward the extended side, and when the shock absorber main body 1 contracts until the first coil spring 7 reaches its tight length and then contracts further, the second coil spring 8 exerts an elastic force proportional to the spring constant of the shock absorber main body 1, urging the shock absorber main body 1 toward the extended side. Therefore, the shock absorber D generates a spring force equal to a low spring constant multiplied by the total compressed length of the first coil spring 7 and the second coil spring 8 until the first coil spring 7 reaches its full length, and after the first coil spring 7 reaches its full length, the spring constant is changed to a higher value, generating a spring force equal to the high spring constant multiplied by the compressed length of the second coil spring 8.

[0032] In this way, the shock absorber D has the first coil spring 7, the second coil spring 8, and the movable spring bearing 6 interposed between the cylinder side spring bearing 4 and the rod side spring bearing 5, so that when the contraction amount of the shock absorber body 1 increases, the first coil spring 7 reaches its tight length and only the second coil spring 8 exerts its elastic force, so that when the degree of contraction of the shock absorber body 1 increases, the spring constant is increased halfway through and the shock absorber body 1 is fully contracted, generating a large elastic force and mitigating the impact at the time of full contraction of the shock absorber body 1. Also, when the shock absorber body 1 is used in a normal range where the first coil spring 7 does not reach its tight length without reaching the stroke end on the contraction side, the first coil spring 7 and the second coil spring 8 generate an elastic force, so that the first coil spring 7 and the second coil spring exert a relatively small elastic force, and the elastic force of the shock absorber D that expands and contracts in the normal range does not become excessive, thereby improving the ride comfort in a saddle-type vehicle.

[0033] The length of the protective tube 6b in the movable spring bearing 6 is set so that when the shock absorber body 1 contracts and the first coil spring 7 is at the tight length and the movable spring bearing 6 is disposed at the uppermost position relative to the cylinder 2, the lower end of the protective tube 6b in FIG. 1 at least protrudes toward the rod side from the lower end in FIG. 1, which is the rod side end of the cylinder 2, and covers and protects the lower side of the cylinder 2. The length of the protective tube 6b in the movable spring bearing 6 is set so that when the shock absorber body 1 contracts to the maximum and the rod side spring bearing 5 approaches the lower end in FIG. 1 of the protective tube 6b, the rod side spring bearing 5 and the protective tube 6b face each other with a gap in the axial direction and do not interfere with each other. Therefore, even if the shock absorber body 1 expands and contracts from the maximum extension state to the maximum contraction state, the protective tube 6b of the movable spring bearing 6 does not interfere with the rod side spring bearing 5, and always protrudes from the lower end of the cylinder 2 to the rod side and is disposed between the second coil spring 8 and the cylinder 2, so that interference between the second coil spring 8 and the cylinder 2 can be prevented.

[0034] Furthermore, the movable spring bearing 6 is equipped with a protective tube 6b, and the inner circumference of the protective tube 6b is brought into sliding contact with the outer circumference of the cylinder 2 from the seat portion 6a, so that the fitting length with respect to the cylinder 2 is longer than that of a conventional movable spring bearing, and tilting with respect to the cylinder 2 is prevented even if the shock absorber body 1 expands or contracts.

[0035] As described above, the shock absorber D of this embodiment includes a shock absorber body 1 having a cylinder 2 and a rod 3 inserted into the cylinder 2 so as to be axially movable, and generating a damping force when extended or contracted, a cylinder side spring bearing 4 attached to the outer periphery of the cylinder 2, a rod side spring bearing 5 attached to the rod 3, a movable spring bearing 6 arranged on the outer periphery of the cylinder 2 and movable in the axial direction relative to the cylinder 2, a first coil spring 7 interposed between the cylinder side spring bearing 4 and the movable spring bearing 6, and a second coil spring 8 interposed between the rod side spring bearing 5 and the movable spring bearing 6, and the movable spring bearing 6 includes a seat portion 6a sandwiched between the first coil spring 7 and the second coil spring 8, and a protective tube 6b that is cylindrical and extends from the seat portion 6a toward the rod side to cover the outer periphery of the cylinder, and when the shock absorber body is fully extended, the tip of the protective tube 6b protrudes toward the rod side beyond the rod side end of the cylinder 2.

[0036] In the shock absorber D configured in this manner, even when the shock absorber body 1 expands or contracts, the movable spring bearing 6 is always present between the cylinder 2 and the second coil spring 8, thereby preventing interference between the cylinder 2 and the second coil spring 8, and also preventing flying stones that fly in while the saddle-type vehicle is traveling from reaching the cylinder 2 even if they pass between the wires of the second coil spring 8 by the protective tube 6b.

[0037] Therefore, according to the shock absorber D of this embodiment, the protective tube 6b of the movable spring bearing 6 can prevent the second coil spring 8 from damaging the outer periphery of the cylinder 2 and prevent flying stones from colliding with the cylinder 2, and the outer periphery that forms the sliding surface of the movable spring bearing 6 of the cylinder 2 is protected, ensuring smooth axial movement of the movable spring bearing 6 relative to the cylinder 2, thereby realizing smooth operation of the shock absorber main body 1 and improving the ride comfort in saddle-type vehicles.

[0038] Furthermore, in the shock absorber D of this embodiment, the protective tube 6b and the rod side spring bearing 5 always face each other with a gap in the axial direction regardless of the expansion / contraction state of the shock absorber main body 1. This allows the protective tube 6b to protect the outer periphery of the cylinder 2 while avoiding interference between the protective tube 6b and the rod side spring bearing 5. This prevents the generation of impact noise due to a collision between the protective tube 6b and the rod side spring bearing 5 when the shock absorber main body 1 is fully contracted, and does not cause discomfort to passengers of the saddle-type vehicle.

[0039] Furthermore, in the shock absorber D of this embodiment, the movable spring bearing 6 has a hole (communication portion) 6b1 that communicates the inside and outside of the protective tube 6b, so that even if water or dust gets in between the protective tube 6b and the cylinder 2, it can be discharged to the outside of the protective tube 6b through the hole (communication portion) 6b1. Therefore, according to the shock absorber D configured in this manner, it is possible to prevent water or dust from accumulating between the protective tube 6b and the cylinder 2 and interfering with smooth movement of the movable spring bearing 6 relative to the cylinder 2.

[0040] In addition, the movable spring bearing 6 in this embodiment is provided with an engagement tube 6c that engages with the inner periphery of the first coil spring 7 above the seat portion 6a in Figure 1, and not only the inner periphery of the protective tube 6b but also the inner periphery of the engagement tube 6c is in sliding contact with the outer periphery of the cylinder 2, so that the axial engagement length can be increased accordingly, and the radial movement of the first coil spring 7 relative to the cylinder 2 is restricted, thereby preventing interference between the first coil spring 7 and the cylinder 2 and protecting the part of the cylinder 2 located on the inner periphery of the first coil spring 7 from flying stones by the engagement tube 6c.

[0041] In shock absorber D of this embodiment, the first coil spring 7 reaches its contact length, causing the apparent overall spring constant of the first coil spring 7 and the second coil spring 8 to change midway through the stroke of the shock absorber body 1. However, the spring constant may be changed more than the apparent spring constant by restricting further compression of the first coil spring 7 by abutting the lower end of the mating tube 6c of the movable spring bearing 6 against the spring seat 4b of the cylinder side spring bearing 4.

[0042] When the movable spring bearing 6 is made of synthetic resin, it may be formed of split pieces (components) P, P divided into two in the radial direction as shown in Fig. 2. In this case, the movable spring bearing 6 is formed by combining two split pieces P, P each having a semicircular semi-cylindrical portion 20 divided in half in the radial direction and a semicircular protruding portion 21 protruding in the radial direction from the outer periphery of the semi-cylindrical portion 20. When the split pieces P, P are combined with each other by butting their circumferential ends together in this way, the seat portion 6a is formed by the protruding portions 21, 21, a protective tube 6b is formed in a portion below the protruding portions 21, 21 in Fig. 2(a) and a fitting tube 6c is formed in a portion above the protruding portions 21, 21 in Fig. 2(a). In Figure 2(a) below the convex portion 21 of the semi-cylindrical portion 20 of the split pieces P, P, a hole 20a is provided, and a groove 20b is formed along the axial direction on the outer periphery, with the hole 20a forming a hole 6b1 and the groove 20b forming a groove 6b2.

[0043] In this way, when the movable spring bearing 6 is formed of split pieces (components) P,P divided into two in the radial direction, each split piece P can be easily manufactured by injection molding using a mold with a simple shape, and manufacturing costs can be reduced. In addition, when the movable spring bearing 6 is formed of split pieces (components) P,P divided into two in the radial direction, the protective tube 6b is inserted into the second coil spring 8. Therefore, when the movable spring bearing 6 is assembled to the shock absorber body 1 together with the second coil spring 8, the movable spring bearing 6 can be attached to the shock absorber body 1 without being separated into the split pieces P,P by the second coil spring 8. In order to prevent the split pieces P,P from being separated from each other, a washer may be stacked on one or both of the upper and lower ends in FIG. 2(a) of the sheet portion 6a formed by the protrusions 21,21. Since the washer is sandwiched between the first coil spring 7 and the second coil spring 8, it does not separate from the seat portion 6a, which effectively prevents separation of the split pieces P, P and provides the advantage that rotation due to expansion and contraction of the first coil spring 7 and the second coil spring 8 is not transmitted by the washer to the movable spring bearing 6. The washer may be an L-shaped washer having a portion that abuts against the outer periphery of the semicylindrical portion 20 and a portion that abuts against the protrusion 21.

[0044] Furthermore, when the movable spring bearing 6 is molded as a single unit, the mold for molding the movable spring bearing 6 is shaped to pull the movable spring bearing 6 in the axial direction, and therefore it is necessary to provide a gradient so that the outer diameter of the protective tube 6b becomes smaller toward the rod side, which is the tip, in consideration of ease of removal from the mold, making it a little more difficult to restrict the radial movement of the second coil spring 8 at the tip side of the protective tube 6b. In contrast, if the movable spring bearing 6 is formed of split pieces (components) P, P split into two in the radial direction, it is sufficient to pull the split piece P out of the mold in the radial direction, and therefore it is not necessary to provide a gradient as described above on the outer periphery of the protective tube 6b, and it becomes possible to restrict the radial movement of the second coil spring 8 over the entire length of the protective tube 6b.

[0045] 3, the movable spring bearing 6 may be formed so that the protective tube 6b is detachable from the seat portion 6a. In this case, for example, a connecting tube 6b3 having a large inner diameter is provided at the lower end of the cylindrical protective tube 6b, and a plurality of flaps 6b4 protruding radially inward are provided at the inner periphery of the connecting tube 6b3. A cylindrical inserting portion 6a1 that can be inserted into the connecting tube 6b3 is provided on the protective tube 6b side of the seat portion 6a, and an annular groove 6a2 that allows the flaps 6b4 to fit is provided on the inner periphery of the base end of the inserting portion 6a1. The inserting portion 6a1 is inserted into the connecting tube 6b3, and the flaps 6b4 are fitted into the annular groove 6a2 to connect the protective tube 8b and the seat portion 6a. In this case, the seat portion 6a and the fitting tube 6c may be integrally molded. As described above, the return protrusions 6b4 may be provided at intervals at multiple locations on the inner circumference of the protective tube 6b, or may be formed as a single annular protrusion that extends around the entire inner circumference of the protective tube 6b.

[0046] In this way, when the movable spring bearing 6 is formed so that the protective tube 6b is detachable from the seat portion 6a, when manufacturing a plurality of shock absorbers D with different specifications having different lengths of cylinder 2, there is an advantage in that if protective tubes 6b of different lengths are prepared, the movable spring bearing 6 can be easily manufactured by selecting the protective tube 6b according to the overall length of the cylinder 2. Note that the structure for connecting the seat portion 6a and the protective tube 6b is not limited to that shown in Fig. 3, and any connecting structure such as press-fitting, adhesion, or the like can be used as long as the two can be connected.

[0047] 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]

[0048] DESCRIPTION OF SYMBOLS 1... Shock absorber body, 2... Cylinder, 3... Rod, 4... Cylinder side spring holder, 5... Rod side spring holder, 6... Movable spring holder, 6a... Seat portion, 6b... Protective tube, 6b1... Hole (communication portion), 7... First coil spring, 8... Second coil spring

Claims

1. a shock absorber body having a cylinder and a rod inserted into the cylinder so as to be movable in the axial direction, the shock absorber body generating a damping force when expanding and contracting; a cylinder side spring bearing attached to an outer periphery of the cylinder; A rod side spring bearing attached to the rod; a movable spring bearing disposed on an outer periphery of the cylinder and movable in an axial direction relative to the cylinder; a first coil spring interposed between the cylinder side spring bearing and the movable spring bearing; a second coil spring interposed between the rod side spring bearing and the movable spring bearing, The movable spring bearing has a seat portion that is sandwiched between the first coil spring and the second coil spring, and a protective tube that is tubular and extends from the seat portion toward the rod side to cover the outer periphery of the cylinder, and when the shock absorber body is fully extended, a tip of the protective tube protrudes toward the rod side beyond the rod side end of the cylinder. A shock absorber characterized by:

2. The protective cylinder and the rod side spring bearing always face each other with a gap in the axial direction regardless of the expansion / contraction state of the shock absorber body.

2. The shock absorber according to claim 1 .

3. The movable spring bearing has a communication portion that communicates the inside and outside of the protective tube.

3. The shock absorber according to claim 1 or 2.

4. The movable spring bearing is formed of a part divided into two parts in the radial direction.

3. The shock absorber according to claim 1 or 2.

5. The protective tube is detachable from the sheet portion.

3. The shock absorber according to claim 1 or 2.

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