JP5220907B2 - Shock absorber - Google Patents

Description

The present invention relates to an improved shock absorber.

As this type of shock absorber having a discharge passage for discharging liquid from the inside of the cylinder to the reservoir, for example, there is one that is set to a uniflow type. In such a shock absorber, the reservoir from the extension side chamber in the cylinder during the extension stroke is used. The liquid is discharged from the reservoir to the pressure side chamber, and a resistance is given to the flow of the liquid discharged to the reservoir by a damping valve so as to generate a damping force.

In such a shock absorber that discharges liquid from the cylinder to the reservoir, especially when used in an upright position, the liquid is discharged from the expansion side chamber to the reservoir during the expansion / contraction stroke as described above. When the extension side chamber is connected to the reservoir, the liquid discharged into the reservoir entrains the gas filled above the reservoir and promotes the mixing of the gas into the liquid in the reservoir. Further, when the shock absorber is in the extension stroke, the liquid is supplied from the reservoir to the pressure side chamber at the same time as the discharge, so that a liquid mixed with gas is supplied to the pressure side chamber. This leads to an unfavorable situation in the shock absorber, such as a poor rise in the nature of the generated damping force and a reduction in damping force.

Therefore, in order not to cause such a situation, a shock absorber is known in which a pipe extending to the lower side of the reservoir is attached to the head member that is fitted to the cylinder and has a passage that connects the extension side chamber and the reservoir. In the case of such a shock absorber, it is possible to prevent entrainment of gas during liquid discharge (see, for example, Patent Document 1).

JP 2002-349629 A (FIG. 2)

In this conventional shock absorber, it is sufficient that gas can be prevented from being entrained as described above. However, vibrations are frequently input over a long period of time as between the axle of a railway vehicle and a carriage, and can be installed vertically. When used in places where it is used, there are the following concerns.

That is, in the above-described conventional shock absorber, in order to prevent gas entrainment in the reservoir, the pipe is attached to the head member so that the pipe is suspended. , There is a possibility that gas entrapment cannot be prevented.

In order to avoid this, there is a measure to screw the pipe to the head member and apply anaerobic adhesive to the screw joint, but if severe vibration continues to be input, it will fall off as described above. There is still some anxiety that it may not be possible to completely prevent it.

Therefore, the present invention was devised to improve the above-mentioned problems, and an object of the present invention is to provide a shock absorber that can reliably prevent gas entrainment in the reservoir when liquid is discharged from the cylinder to the reservoir. That is.

In order to solve the above-described object, the problem-solving means of the present invention includes a cylinder, a head member that closes the upper end of the cylinder, a sliding member that is slidably inserted into the cylinder, and an extension chamber inside the cylinder. A shock absorber comprising: a piston that is partitioned into a pressure side chamber; an outer cylinder that is disposed on the outer peripheral side of the cylinder and forms a reservoir with the cylinder; and a discharge passage that discharges the liquid in the cylinder to the reservoir The cylinder or the outer cylinder is positioned in a radial direction to form an air chamber between the cylinder or the outer cylinder and the cylinder or the other outer cylinder. A cylinder member that forms a part of the discharge passage between the cylinder and the cylinder member, and a fitting portion that fits into one of the cylinder or the outer cylinder, and the cylinder or A cylindrical portion that forms an annular passage that forms a part of the discharge passage with the other of the outer cylinder, and a connecting portion that connects the fitting portion and the cylindrical portion. A step is provided on the inner periphery of the cylinder, the upper end of the fitting portion is brought into contact with the lower end of the head member, and the portion rising from the connection portion of the fitting portion is brought into contact with the step portion. by the head member with the movement of the said pressure side chamber side it is is restricted by the stepped portion and is characterized in that the movement to the expansion side chamber side is restricted.

According to the shock absorber of the present invention, it is discharged below the reservoir through the discharge passage that is isolated from the air chamber by the cylindrical member, so there is no possibility of entraining the gas in the air chamber when the hydraulic oil is discharged.

According to the invention of each claim, even if vibration is continuously and frequently input to the shock absorber, the cylinder member forms an air chamber in cooperation with the cylinder or the outer cylinder. Even if a positional shift occurs with respect to the cylinder or the outer cylinder, the gas entrainment can be prevented.
Further, even if vibration is continuously and frequently input to the shock absorber, the cylindrical member is positioned in the radial direction on one of the cylinder or the outer cylinder, so that the cylindrical member falls off and is not supported at all in the reservoir. You can also prevent situations where you play.
Further, since the upper end of the fitting portion is brought into contact with the lower end of the head member and the portion rising from the connection portion of the fitting portion is brought into contact with the step portion, the cylindrical member is sandwiched between the head member and the step portion. Thus, the vertical movement is restricted, so that the cylinder member is reliably prevented from playing in the reservoir.
According to the invention of claim 2, since the lower end of the cylindrical portion is expanded or contracted in a funnel shape, the speed of hydraulic oil that has passed at a high speed is gradually reduced to suppress generation of turbulent flow. In addition, the generation of bubbles (aeration) in the hydraulic oil due to sudden pressure reduction is suppressed.
Therefore, hydraulic oil containing bubbles may be supplied into the pressure side chamber during the expansion stroke of the shock absorber in which the hydraulic oil is discharged from the cylinder to the reservoir and supplied from the reservoir to the cylinder at the same time. Is prevented.

In addition, unlike the conventional shock absorber, it is not necessary to screw the pipe and bond it with an anaerobic adhesive, which simplifies the manufacturing process. Further, in the case where the discharge passage is branched into a plurality by the head member and communicates with the extension side chamber, in the conventional shock absorber, the number of pipes corresponding to the number of discharge passages must be provided. In the container, the discharge passage branched by accommodating one cylindrical member in the reservoir can be converged by a single annular passage, which is advantageous in terms of processing cost and man-hour.

It is a longitudinal cross-sectional view of the shock absorber in one reference example. It is a longitudinal cross-sectional view of the shock absorber in another reference example. It is a longitudinal cross-sectional view of the shock absorber in another reference example. It is a longitudinal cross-sectional view of the shock absorber in one embodiment. It is a partially expanded longitudinal cross-sectional view of the shock absorber in still another reference example. Furthermore, it is a partially expanded longitudinal cross-sectional view of the shock absorber in another reference example.

The present invention will be described below based on the embodiments shown in the drawings. FIG. 1 is a longitudinal sectional view of a shock absorber in a reference example. FIG. 2 is a partially enlarged longitudinal sectional view of a shock absorber according to another reference example. FIG. 3 is a partially enlarged longitudinal sectional view of a shock absorber according to another reference example. FIG. 4 is a partially enlarged longitudinal sectional view of a shock absorber according to an embodiment of the invention of claim 1. FIG. 5 is a partially enlarged longitudinal sectional view of a shock absorber in still another reference example. FIG. 6 is a partially enlarged longitudinal sectional view of a shock absorber in still another reference example.

As shown in FIG. 1, the shock absorber D in the reference example includes a cylinder 1 and a piston 2 that is slidably inserted into the cylinder 1 and divides the cylinder 1 into an extension side chamber R1 and a pressure side chamber R2. A rod 3 which is movably inserted into the cylinder 1 and whose one end is connected to the piston 2; an outer cylinder 4 which is disposed on the outer peripheral side of the cylinder 1 and forms a reservoir R between the cylinder 1; And a cylindrical member 6 which is positioned in the outer cylinder 4 in the radial direction and forms an air chamber G with the outer cylinder 4 and forms a discharge passage 5 with the cylinder 1. In the case of the shock absorber D of the embodiment, it is set to a uniflow type.

The extension side chamber R1, the pressure side chamber R2 and the reservoir R are filled with hydraulic fluid, and the reservoir R is also filled with gas in an air chamber G formed by the cylindrical member 6.

Further, since the shock absorber D is set to be a uniflow type, the rod 3 enters the cylinder 1 during the contraction stroke, so that excess hydraulic oil enters the cylinder 1 through the discharge passage 5 from the cylinder 1. In addition, the rod 3 is withdrawn from the cylinder 1 during the extension stroke, so that the hydraulic oil in the extension side chamber R1 is discharged to the reservoir R through the discharge passage 5, and the cylinder 2 is displaced by the upward displacement of the piston 2. Insufficient hydraulic oil is supplied from the reservoir R to the pressure side chamber R2, so that the flow of oil is always one-way from the pressure side chamber R2 to the extension side chamber R1 in both strokes. Furthermore, a pressure increasing passage 7 that allows only the flow of liquid from the pressure side chamber R2 to the expansion side chamber R1, and a supply passage 8 that allows only the flow of liquid from the reservoir R to the pressure side chamber R2. It is provided.

Hereinafter, each part will be described in detail. The cylinder 1 is formed in a cylindrical shape, and its upper end is closed by a head member 9 that forms a part of the discharge passage 5, and the lower end is a valve provided with a supply passage 8. It is closed by the disk 10 and filled with hydraulic fluid as a liquid. In the present embodiment, the liquid is hydraulic oil, but is not limited to this, and other liquids may be used.

The cylinder 1 is partitioned into an expansion side chamber R1 and a compression side chamber R2 by a piston 2 that is slidably inserted. The piston 2 is connected to the lower end of a rod 3, and the rod 3 is connected to the head member 9 by a cylinder. Is slidably supported by the shaft.

An outer cylinder 4 that covers the cylinder 1 and forms a reservoir R between the cylinder 1 and the cylinder 1 is provided outside the cylinder 1, and the head member 9 is fitted to the inner periphery of the upper end of the outer cylinder 4. In addition, the lower cap 11 is joined to the lower end, and the inside of the outer cylinder 4 is sealed.

The piston 2 includes a port 7a that allows the extension side chamber R1 and the pressure side chamber R2 to communicate with each other. The port 7a is opened and closed by a check valve 7b disposed at the upper end of the piston 2. The check valve 7b is urged by a spring (not shown), and when the hydraulic oil moves from the pressure side chamber R2 to the extension side chamber R1, the spring is compressed by the hydraulic oil and retracts from the piston 2. In contrast, the port 7a is opened, but conversely, with respect to the flow in which the hydraulic oil is about to move from the expansion side chamber R1 to the compression side chamber R2, the port 7a is kept closed to prevent the flow. That is, in this embodiment, the pressure increasing passage 7 is constituted by the port 7a and the check valve 7b. In addition, although the pressure expansion passage 7 is provided in the piston 2, the flow toward the expansion side chamber R1 from the pressure side chamber R2 by bypassing the piston 2 may be allowed.

The head member 9 has a cylindrical shape, a flange 9a formed on the outer peripheral side, a small diameter portion 9b having a small inner diameter at the inner periphery at the upper end in FIG. 1, and a large diameter having a large inner diameter at the inner periphery at the lower end in FIG. A portion 9c, an intermediate portion 9d having an inner diameter between the small-diameter portion 9b and the large-diameter portion 9c between the small-diameter portion 9b and the large-diameter portion 9c, and a discharge passage that opens from the intermediate portion 9d to the lower end of the flange 9a 5, a valve hole 9 e forming a part of 5, a groove 9 f provided at the upper end of the small-diameter portion 9 b, and a fitting portion 9 g that opens from the lower end and continues to the large-diameter portion 9 c.

In addition, a cylindrical bearing 12 that is slidably contacted with the outer periphery of the rod 3 and guides the movement of the rod 3 in the vertical direction in FIG. In addition, a seal member 13 that slides in contact with the outer periphery of the rod 3 and seals the outer periphery of the rod 3 is accommodated in the groove 9f and fixed by a snap ring (not shown).

The inner diameter of the large diameter portion 9c is set to a diameter that allows a sufficient gap to be formed between the large diameter portion 9c and the hydraulic oil can flow into the valve hole 9e from the expansion side chamber R1 through this gap. ing. Further, the axial length of the bearing 12 is considered so that the movement of the rod 3 can be sufficiently guided, and the opening position of the valve hole 9e on the large diameter portion 9c side does not block the valve hole 9e with the bearing 12. It is natural that this is taken into account.

Further, the head member 9 is configured such that the outer periphery of the flange 9a is fitted into the inner circumference of the outer cylinder 4, and is fitted into the fitting portion 9g having a larger diameter than the large diameter portion 9c provided at the lower end. The cylinder 1 is positioned in the radial direction with respect to the outer cylinder 4.

A damping valve 14 is provided in the valve hole 9e. The damping valve 14 provides resistance to the flow of hydraulic oil passing through the valve hole 9e during the expansion / contraction stroke of the shock absorber D, and the shock absorber. D causes the damping force to be exerted.

Subsequently, the valve disc 10 includes a main body 10a having a diameter larger than that of the cylinder 1, a cylindrical convex portion 10b fitted to the lower end in FIG. 1 of the cylinder 1, and a port 10c that opens from the outer periphery of the main body 10a and communicates with the upper end. It is configured with. Then, the valve disk 10 is fitted with a body 10a in a recess 11a of a lower cap 11 fixed to the lower end of the outer cylinder 4, and a head member with a nut 25 screwed into the inner periphery of the upper end in FIG. 1 is fixed to the outer cylinder 4 together with the cylinder 1 and the head member 9 by tightening 9 downward in FIG.

A check valve 15 is disposed on the upper surface of the valve disk 10 in FIG. 1, and the port 10 c is opened and closed by the check valve 15. The check valve 15 is urged by a spring (not shown). When the hydraulic oil moves from the reservoir R to the pressure side chamber R2, the check valve 15 is pushed by the hydraulic oil and the spring is contracted to retract from the valve disk 10. In contrast, the port 10c is opened, but conversely, the flow of hydraulic fluid from the pressure side chamber R2 to the reservoir R is prevented from flowing while the port 10c is kept closed. That is, in the case of this reference example, the supply passage 8 is constituted by the port 10 c and the check valve 15.

Subsequently, in the shock absorber D, the cylindrical member 6 is accommodated in the reservoir R. The cylindrical member 6 includes a fitting portion 6a that fits on the inner periphery of the outer tube 4, a cylindrical portion 6b that forms a discharge passage 5 between the outer periphery of the cylinder 1, and a fitting portion 6a and a cylindrical portion 6b. The fitting portion 6a is restricted from moving toward the pressure side chamber R2 which is the lower side in FIG. 1 by the step portion 4a provided on the inner periphery of the outer cylinder 4. Yes.

In the case of this cylindrical member 6, the fitting portion 6a is formed in a cylindrical shape so that it can be fitted to the inner periphery of the outer cylinder 4, and the inner diameter of the cylindrical portion 6b is set to be larger than the outer diameter of the cylinder. A constant annular gap is formed along the outer periphery of the cylinder 1 with the cylinder 1, and the lower end is expanded in a funnel shape. An annular passage 16 that forms part of the discharge passage 5 is formed by the gap between the cylinder portion 6b and the cylinder 1, and the valve passage 9e communicates with the lower part of the reservoir R in FIG. The annular passage 16 and the valve hole 9e form the discharge passage 5.

Moreover, the connection part 6c continues to the upper end of the fitting part 6a and the upper end of the cylinder part 6b. In this case, the cylinder member 6 can be manufactured by pressing a pipe material.

When the cylindrical member 6 is accommodated in the reservoir R and the cylindrical member 6 is fitted to the inner periphery of the outer cylinder 4, the chamber is partitioned into the reservoir R by the cylindrical member 6, and gas is filled in the chamber. An air chamber G is formed, and gas does not enter the space A between the tubular member 6 and the flange 9a of the head member 9.

Moreover, since the cylindrical member 6 is fitted to the outer cylinder 4, it is positioned in the radial direction, the cylindrical portion 6b is prevented from interfering with the cylinder 1, and the discharge passage 5 can be stably formed. It is like that.

Furthermore, since the lower end of the cylinder part 6b is expanded, the speed of the hydraulic oil discharged from the extension side chamber R1 and passing between the cylinder part 6b and the cylinder 1 at a high speed is gradually reduced. While suppressing the generation of turbulent flow below the reservoir R where the suction port of the supply passage 8 is located, the generation of bubbles (aeration) in the hydraulic oil due to sudden pressure reduction is suppressed.

Therefore, hydraulic oil containing bubbles in the compression side chamber R2 is provided during the expansion stroke of the shock absorber D in which the hydraulic oil is discharged from the cylinder 1 to the reservoir R and the hydraulic oil is supplied from the reservoir R to the cylinder 1 at the same time. Is prevented from being supplied.

Subsequently, in the shock absorber D configured as described above, when the piston 2 is extended, the piston 2 moves upward in FIG. 1 with respect to the cylinder 1, so that the volume of the extension side chamber R1 is reduced, so that the reduced volume is commensurate. The hydraulic oil is pushed out, the hydraulic oil pushes open the damping valve 14 in the valve hole 9e, and the discharge passage is formed by the annular passage 16 between the valve hole 9e and the cylindrical portion 6b of the cylindrical member 6 and the cylinder 1. 5 to the reservoir R.

On the other hand, hydraulic oil commensurate with the expanded volume is supplied from the reservoir R via the supply passage 8 to the pressure side chamber R2 whose volume is expanded by moving the piston 2 upward in FIG.

During this extension stroke, the hydraulic oil discharged from the expansion side chamber R1 to the reservoir R is discharged below the reservoir R through the discharge passage 5 isolated from the air chamber G by the cylindrical member 6 as described above. There is no possibility of entraining the gas in the air chamber G when the hydraulic oil is discharged.

Even if vibrations are continuously and frequently input to the shock absorber D, the cylinder member 6 cooperates with the outer cylinder 4 to form the air chamber G. On the other hand, even if a positional shift occurs in the vertical direction in FIG.

Furthermore, even if vibration is continuously input to the shock absorber D, the cylinder member 6 falls off from the outer cylinder 4 and plays in the reservoir R without being supported at all because it is positioned in the radial direction. It is possible to prevent a situation in which abnormal noise is generated due to interference with the cylinder 1.

Furthermore, since the fitting portion 6a of the tubular member 6 restricts the movement of the tubular member 6 toward the pressure side chamber R2 by the step portion 4a of the outer tube 4, the downward movement of the tubular member 6 can be reliably prevented. It is possible to reliably prevent the cylindrical member 6 from interfering with the lower cap 11 and generating abnormal noise. In addition, since the cylinder member 6 is comprised by the fitting part 6a, the connection part 6c, and the cylinder part 6b, the space A where the hydraulic fluid discharged | emitted from the expansion side chamber R1 ejects above the reservoir | reserver R is formed. Since the fitting part 6a of the cylindrical member 6 is restricted from moving toward the pressure side chamber R2 by the step part 4a of the outer cylinder 4, the cylindrical member 6 is pressed downward by the pressure generated in the space A. The movement of the cylindrical member 6 in the vertical direction in FIG. 1 can be suppressed.

When the cylindrical member 6 is fixed to the outer cylinder 4 by simply press-fitting the fitting part 6a into the inner periphery of the outer cylinder 4 without providing the stepped part 4a, the air at the lower end side in FIG. If a notch or hole that communicates the inside and the outside of the cylinder portion 6b is provided in a portion that does not face the chamber G, the hydraulic oil can be removed through the notch or hole even if the cylinder member 6 moves to the lowest end. Since distribution is ensured, the damping function required for the shock absorber D is not impaired.

In addition, unlike the conventional shock absorber, it is not necessary to screw the pipe and bond it with an anaerobic adhesive, which simplifies the manufacturing process. Further, when the discharge passage 5 is branched into a plurality at the head member 9 and communicates with the extension side chamber R1 such as by providing a plurality of valve holes 9e, the conventional shock absorber has a number of pipes corresponding to the number of discharge passages. Although it is necessary to provide the shock absorber D according to the reference example, the discharge passage 5 branched by accommodating one cylindrical member 6 in the reservoir R can be converged by a single annular passage 16. This is advantageous in terms of manufacturing cost, processing cost, and processing man-hours.

In addition, when it is desired to more reliably prevent gas leakage from the air chamber G partitioned by the cylindrical member 6, the lower end in FIG. 1 of the fitting portion 6a suspended from the outer periphery of the connection portion 6c is connected to the lower end of the air chamber G. What is necessary is just to set so that it may be arrange | positioned below, or to interpose a seal ring between the fitting part 6a and the outer cylinder 4, and also as shown in FIG. 2, the exit end of the valve hole 9e Gas leakage from the air chamber G may be prevented by interposing the seal ring 17 in a compressed state between the head member 9 and the connection portion 6c so as not to block the air. As described above, when the seal ring 17 is interposed between the head member 9 and the connecting portion 6c, the tubular member 6 is pressed downward in FIG. 2, so that the fitting portion 6a becomes the step portion 4a. It is possible to prevent the cylinder member 6 from playing in the reservoir R, and it is possible to prevent the cylinder member 6 from playing in the reservoir R at the same time.

Further, in the case of this reference example, the cylindrical member 6 is fitted and fixed to the outer cylinder 4, but on the contrary, as shown in FIG. You may make it match. The tubular member 18 has a structure in which the arrangement of the fitting portion 6a and the tubular portion 6b in the tubular member 6 described above is replaced with the connecting portion 6c interposed therebetween, and the fitting portion 18a is arranged on the inner peripheral side of the connecting portion 18c. And a cylindrical portion 18b is provided on the outer peripheral side of the connecting portion 18c.

The cylindrical member 18 is fixed to the cylinder 1 by being fitted with the fitting portion 18a on the outer periphery of the cylinder 1 in the radial direction. The step portion 1a provided on the outer periphery of the cylinder 1 in FIG. Movement to the pressure side chamber R2 side, which is the lower side, is restricted.

Further, the cylindrical portion 18 b forms an annular passage 19 that forms a part of the discharge passage 5 with the inner periphery of the outer cylinder 4, and the lower end of the cylindrical portion 18 b is reduced in diameter so as to move away from the outer cylinder 4. Thus, the flow passage area of the annular passage 19 is gradually enlarged.

In this way, the cylindrical member 18 is fixed to the cylinder 1 side unlike the above-described cylindrical member 6, and forms an air chamber G in cooperation with the cylinder 1, and on the outer peripheral side of the cylindrical portion 18b. Although the annular passage 19 isolated from the air chamber G is formed, the same function and effect as the cylindrical member 6 can be obtained even in this way.

FIG. 4 relates to an embodiment of the invention of claim 1, and instead of the reference example of FIGS. 1 to 3, the configurations of the cylindrical portion 20 b and the connecting portion 20 c are the same as those of the cylindrical member 6 of the reference example. The fitting part 20a of the cylindrical member 20 is made to rise from the outer periphery of the connection part 20c. In this case, the upper end of the fitting portion 20a is brought into contact with the lower end of the flange 9a of the head member 9, and the portion rising from the connecting portion 20c of the fitting portion 20a is brought into contact with the step portion 4a of the outer cylinder 4. For example, since the cylinder member 20 is sandwiched between the head member 9 and the step portion 4a of the outer cylinder 4 and the movement in the vertical direction is restricted, the cylinder member 20 is reliably prevented from playing in the reservoir R. You can also.

Further, as shown in another reference example of FIG. 5, the configuration of the fitting portion 21 a and the connecting portion 21 c is the same as that of the cylindrical member 20, while the vertical length in FIG. 5 is the axial length of the cylindrical member 21. The length in the direction may be set to a length that can be sandwiched between the head member 9 and the lower cap 11, and the notch 21d may be provided at an arbitrary position below the lower end of the air chamber G of the cylindrical portion 21b. .

In this case, the upper end of the fitting portion 21 a is in contact with the lower end of the flange 9 a of the head member 9, and the lower end of the cylinder portion 21 b is in contact with the lower cap 11. In addition, the fitting portion 21a is fitted into the inner periphery of the outer cylinder 4 and is positioned in the radial direction in the reservoir R. As shown in another reference example of FIG. 6, when restricting the vertical movement of the cylindrical member 21, it is between the lower end of the cylindrical member 21 and the lower cap 11, that is, the lower end of the cylindrical portion 21 b and the lower cap. 11, an elastic body 23 such as a spring washer, a spring, or rubber may be interposed between the cylinder member 21 and the head member 9.

In addition, in this cylindrical member 21, the communication between the air chamber G side and the annular passage 22 formed between the cylindrical portion 21b and the cylinder 1 is ensured through the notch 21d. There is no damage. Of course, the communication between the annular passage 22 and the air chamber G side may be performed via a hole 21e provided in place of the notch 21d as shown in FIG.

Even in this cylindrical member 21, the air chamber G is formed in cooperation with the outer cylinder 4, and an annular passage 22 isolated from the air chamber G is formed on the inner peripheral side of the cylindrical portion 21b. Therefore, even if it does in this way, while having the same effect as the cylinder member 6, since a vertical movement is controlled, it is surely prevented that the cylinder member 21 is idle in the reservoir R. You can also Note that the tubular member 21 may be fixed to the cylinder 1 by changing the arrangement of the fitting portion 21a and the tubular portion 21b of the tubular member 21 with the connection portion 21c interposed therebetween.

The description of the reference example and the embodiment of the present invention is finished as above, but it is needless to say that the scope of the present invention is not limited to the details shown or described.

DESCRIPTION OF SYMBOLS 1 Cylinder 1a Step part 2 in a cylinder Piston 3 Rod 4 Outer cylinder 4a Step part 5 in an outer cylinder Discharge passage 6, 18, 20, 21 Cylinder member 6a, 18a, 20a, 21a Fitting part 6b, 18b, 20b, 21b Cylinder Portions 6c, 18c, 20c, 21c Connection portion 7 Pressure increasing passage 7a Port 7b, 15 Check valve 8 Supply passage 9 Head member 9a Flange 9b Small diameter portion 9c Large diameter portion 9d Intermediate portion 9e Valve hole 9f Groove 9g Fitting portion 10 Valve Disc 10a Body 10b in valve disc Cylindrical convex portion 10c in valve disc Port 11 in valve disc Lower cap 11a Concave portion in lower cap 12 Bearing 13 Seal member 14 Damping valve 25 Nut 16, 19, 22 Annular passage 17 Seal ring 21d Notch 21e Hole 23 Elastic body A Space D Buffer G Air chamber R Reservoir R1 Stretch side chamber R2 Pressure side chamber

Claims (3)

A cylinder, a head member that closes the upper end of the cylinder, a piston that is slidably inserted into the cylinder and that divides the cylinder into an extension side chamber and a pressure side chamber, and an outer peripheral side of the cylinder. A shock absorber provided with an outer cylinder that forms a reservoir between the cylinder and a discharge passage that discharges the liquid in the cylinder to the reservoir. The shock absorber is accommodated in the reservoir and is attached to one of the cylinder or the outer cylinder. A cylindrical member that is positioned in a radial direction to form an air chamber between one of the cylinder and the outer cylinder and that forms a part of a discharge passage with the other of the cylinder or the outer cylinder; The cylindrical member is an annular passage that forms part of the discharge passage between a fitting portion that fits into one of the cylinder or the outer cylinder and the other of the cylinder or the outer cylinder. A cylindrical portion which forms, and a connecting portion for connecting the fitting portion and the tubular portion, a step portion is provided on the peripheral within the cylinder periphery or the outer tube, the upper end of the fitting portion of the head member the portion rising from the connecting section of the fitting portion abuts against the lower end is brought into contact with the stepped portion, the head with the fitting portion is moved to the compression side chamber side by the stepped portion formed by regulated A shock absorber characterized in that movement toward the extension side chamber is restricted by a member. The shock absorber according to claim 1, wherein the lower end of the cylindrical portion is expanded or contracted in a funnel shape . A pressure-increasing passage that allows only the flow of liquid from the pressure-side chamber toward the expansion-side chamber, and a supply passage that allows only a flow of liquid from the reservoir toward the pressure-side chamber, and the discharge passage extends from the extension-side chamber. 3. The shock absorber according to claim 1, wherein only a liquid flow toward the reservoir is allowed.

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