JP2011252590A - Hydraulic shock absorber - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optimum attachment method of a balance spring, for example, in a front fork or a rear cushion unit in a motorcycle.SOLUTION: A hydraulic shock absorber includes: an operation chamber which consists of a shock absorber body including an outer tube 1 and an inner tube 2, and working fluid; a reservoir air chamber R which consists of gas enclosed in the shock absorber body, and which functions as an air spring; a piston 15 which divides the operation chamber into a compression side operation chamber P1 and an extension side operation chamber P2; a rod 13 for holding the piston 15; and damping force generation means V1 and V2 for generating a prescribed damping force. A balance spring 4 is provided having one end side fixed with the inner tube 2 and an outer periphery in contact with an inner periphery of the inner tube 2. The balance spring 4 suppresses spring reaction force by the reservoir air chamber R in a prescribed stroke range in which the shock absorber body contracts from a maximum extended state.

Description

  The present invention relates to a fluid pressure shock absorber, and more particularly to an improvement in a front fork and a rear cushion unit that suspends a wheel of a two-wheeled vehicle and attenuates road surface vibration input to the wheel.

  There have been various proposals for a front fork or a rear cushion unit that suspends a wheel of a motorcycle and attenuates road surface vibration input to the wheel. For example, as disclosed in Patent Document 1, The front fork has a suspension spring made up of a coil spring that urges the fork body in the extending direction inside the fork body made up of the vehicle body side tube and the wheel side tube.

  On the other hand, in the front fork disclosed in Patent Document 1, a damper including damping force generating means for generating a predetermined damping force is accommodated in the fork body.

  The damper includes a damper cylinder that stands on the axial center of the vehicle body side tube, a rod that stands on the axial center of the wheel side tube, and is inserted into the damper cylinder so as to be freely retractable. It comprises a piston that divides the inside of the damper cylinder into two pressure chambers, and a damping force generating means that generates a predetermined damping force as the piston moves.

Japanese Patent Laying-Open No. 2008-240840 (FIG. 1)

  A conventional front fork functions as a suspension that absorbs road surface vibration by providing a suspension spring, and can also function as a shock absorber that attenuates road surface vibration by providing a damper.

  However, the conventional front fork has a complicated structure and a large number of parts, which may increase the weight of the front fork.

  Accordingly, an object of the present invention is to provide a hydraulic shock absorber such as a front fork that can be reduced in weight by reducing the number of parts.

  Means for solving the above problems are: a shock absorber body comprising an outer tube, an inner tube inserted and retracted into the outer tube, and a working chamber comprising a working fluid housed in the inner tube. A reservoir air chamber that is made of gas sealed in the shock absorber body and is maintained in a pressure-increasing tendency and functions as an air spring; and an inner periphery of the inner tube that is slidably contacted with the outer periphery. A piston that divides the working chamber into a compression side working chamber and an extension side working chamber, a rod that stands on the axial center of the outer tube and holds the piston, and a predetermined amount as the piston moves. A damping force generating means for generating a damping force, one end side of which is fixed to the inner tube and the outer periphery of the inner tube is fixed. Abutting balance spring provided on the peripheral, the balance spring is to suppress the spring reaction force due to the reservoir air chamber in a predetermined stroke range in which the shock absorber body contracts from the maximum stretched state.

  Since the hydraulic shock absorber according to the present invention includes the reservoir air chamber, the hydraulic shock absorber functions as a suspension without a suspension spring including a coil spring, and thus can be reduced in weight.

  In addition, by providing the balance spring, it is possible to prevent the ride comfort from deteriorating in a predetermined stroke range in which the shock absorber body contracts from the most extended state.

  Further, since the balance spring is fixed to the inner tube and abuts on the inner circumference of the inner tube, buckling can be prevented and the spring diameter can be maximized.

It is a half sectional view showing the maximum extension state of a fluid pressure shock absorber according to an embodiment of the present invention. It is a half sectional view showing the most contracted state of the fluid pressure shock absorber according to the embodiment of the present invention. It is a partial expanded half sectional view which shows the most extended state of the fluid pressure buffer which concerns on one embodiment of this invention. It is a graph which shows the spring characteristic of the fluid pressure buffer which concerns on one embodiment of this invention.

  Hereinafter, a fluid pressure shock absorber showing an embodiment of the present invention will be described with reference to the drawings. The same reference numerals given throughout the several drawings indicate the same or corresponding parts.

  In this embodiment, the fluid pressure shock absorber according to the present invention is embodied in a front fork that suspends a front wheel of a two-wheeled vehicle and attenuates road surface vibration input to the front wheel.

  The front fork is composed of a pair of left and right fork members that stand on both sides of the front wheel of the motorcycle. The fork member includes a buffer including an outer tube 1 and an inner tube 2 that is inserted into and retracted into the outer tube 1. A fork main body as a container main body, a working chamber made of a working fluid accommodated in the inner tube 2, and a gas that is opposed to the working chamber and is sealed in the fork main body and maintained in a pressure increasing tendency as an air spring A functioning reservoir air chamber R, a piston 15 that moves within the working chamber while sliding the outer periphery thereof in contact with the inner circumference of the inner tube 2 and divides the working chamber into a pressure side working chamber P1 and an extension side working chamber P2, A rod 13 that stands on the axial center of the outer tube 1 and holds the piston 15, and a movement of the piston 15 There comprising a damping force generating means for generating a predetermined damping force.

  A balance spring 4 is provided which is fixed at one end to the inner tube 2 and whose outer periphery contacts the inner periphery of the inner tube 2. The balance spring 4 has a predetermined stroke at which the fork main body contracts from the most extended state. The spring reaction force by the reservoir air chamber R in the range is suppressed.

  Below, each component of the front fork in this Embodiment is each demonstrated.

  The front fork includes an outer tube 1 located on the vehicle body side and an inner tube 2 located on the wheel side, and is set upside down.

  Although not shown, the upper end side of the outer tube 2 in the drawing is connected to the handle of the two-wheeled vehicle, and the lower end side of the inner tube 2 in the drawing is connected to the axle of the front wheel of the two-wheeled vehicle.

  Further, the illustrated front fork functions as an air suspension in which a gas is enclosed in a fork main body composed of an outer tube 1 and an inner tube 2, and as a fluid pressure shock absorber as a damper with a damping force generating means. Also works.

  The fork main body is sealed by sealing the upper and lower ends with a cap member 12 and a bottom member 22, and sealing the sliding surfaces of the outer tube 1 and the inner tube 2 with a second seal member 21 described later. .

  The inside of the fork main body refers to a space excluding an oil reservoir chamber 3 described later, which is defined by the second seal member 21, among the spaces formed inside the outer tube 1 and the inner tube 2.

  The interior of the fork main body is located at a lower position and filled with a working oil as a working fluid, and a reservoir air that is located above the oil level O of the working oil and filled with gas and maintained in a pressure-increasing tendency. It is partitioned into a room R.

  The reservoir air chamber R includes an upper air chamber R1 formed in the outer tube 1 and a lower air chamber R2 formed in the inner tube 2, and these air chambers R1 and R2 are always kept in communication. Be drunk.

  The working chamber filled with the working oil is divided into an extension side working chamber P2 located at the upper side in the drawing and a pressure side working chamber P1 located at the lower side in the drawing by a piston 15 slidably contacting the inner circumference of the inner tube 2. Is done.

  The extension side working chamber P2 is pressurized via the oil level O by the gas accommodated in the reservoir air chamber R.

  The piston 15 that divides the working chambers P1 and P2 is held via a distal end member 14 at the distal end of a rod 13 whose base end is fixed to a cap member 12 that seals the upper end of the outer tube 1 in the figure. As the fork body expands and contracts, it moves up and down in the working chamber.

  Although not shown, the piston 15 includes a port that penetrates the wall thickness of the piston 15. The port includes a pressure-side port that communicates each of the working chambers P1 and P2 when the fork body contracts, and when the fork body extends. It consists of an extension side port communicating with each working fluid chamber P1, P2.

  Further, the piston 15 is provided with a damping force generating means, and the damping force generating means permits the pressure side port to communicate only when the fork main body contracts and generates a predetermined damping force, and the fork main body. The extension side leaf valve V2 generates a predetermined damping force by permitting the communication of the extension side port only during the extension.

  By providing the above-described configuration, the reservoir air chamber R pressurizes the expansion side working chamber P2 together with the piston 15 when the fork main body is extended, so that the differential pressure between the expansion side working chamber P2 and the pressure side working chamber P1 is increased. The opening of the side leaf valve V2 can be assisted to prevent the pressure side working chamber P1 from being depressurized and causing aeration.

  Accordingly, the front fork can exhibit a function as a damper without providing a damper cylinder, a rod guide, or the like in the fork main body, and can be formed to be lightweight.

  Further, the gas sealed in the reservoir air chamber R changes its compression ratio due to the volume change of the reservoir air chamber R due to the expansion and contraction of the fork main body, and generates a predetermined spring reaction force corresponding to this compression ratio. Function as.

  Therefore, the front fork can exhibit a function as a suspension without using a suspension spring formed of a coil spring, and further weight reduction can be achieved.

  The gas sealed in the reservoir air chamber R also compensates for the volume change of the reservoir air chamber R that increases or decreases the volume of the rod 13 that appears and disappears into the inner tube 2.

  The configuration of the damping force generating means is not limited to the above, and a known method such as an orifice formed in a port penetrating the piston 15 can be appropriately selected.

  Further, the damping force in the damping force generating means may be adjustable by a known method. As the adjusting method, although not shown, a bypass path that bypasses the damping force generating means and penetrates the piston is provided, and this bypass path A method of changing the opening degree of is known.

  Further, the pressurization of the extension side working chamber P2 by the reservoir air chamber R is set to a predetermined internal pressure that can maintain the inside of the reservoir air chamber R in a pressure increasing tendency by the gas sealed in the reservoir air chamber R. As long as the aeration of the pressure side working chamber P1 can be prevented, it can be set as appropriate.

  However, the spring reaction force is generated by the gas sealed in the reservoir air chamber R even when the fork main body is extended to the maximum when the spring reaction force is preferably zero (FIG. 4, one-dot chain line).

  Therefore, when the reservoir air chamber R is maintained in a pressure-increasing tendency, the fork main body is urged in the expansion direction by the gas in the reservoir air chamber R when the contraction stroke is started from the vicinity of the maximum expansion of the fork main body. Therefore, the contraction stroke is not started quickly, and the ride comfort may be deteriorated.

  Therefore, the front fork according to the present invention includes a balance spring 4 that urges the fork main body in the contracting direction in order to realize a good riding comfort even in the vicinity of the fork main body at its maximum extension.

  The balance spring 4 has a spring characteristic indicated by a broken line in FIG. 4 and is interposed between an upper spring receiver 4a fixed to the inner tube side and a lower spring receiver 4b fixed to the piston side.

  The balance spring 4 suppresses a spring reaction force caused by the reservoir air chamber R in a predetermined stroke range in which the fork main body contracts from the most extended state.

  In the present embodiment, the balance spring 4 acts in the range from the most extended state of the fork main body to about ½ of the full stroke, and the balance spring 4 acts near the time when the fork main body is fully extended. A range.

  The range in which the balance spring 4 acts is not limited to the above, and can be set as appropriate.

  The upper spring receiver 4a is fixed to the insertion side of the inner tube 2 into the outer tube 1, that is, to the lower end of the partition wall member 5 attached to be overlapped with the one end portion located at the upper side in the figure. The receiver 4 b is fixed to a cylindrical case 16 attached to the outer periphery of the tip end portion of the rod 13.

  By providing the structure, the balance spring 4 is compressed when the fork main body is in the extended state, as shown in FIG. 1, and the upper end of the inner tube 2 in the figure and the tip of the rod 13 are separated from each other. The fork main body is urged in a contracting direction because the urging is performed so that 13 enters the inner tube 2.

  Therefore, even when the fork main body is in the vicinity of the maximum extension, the balance spring 4 urges the fork main body in the contracting direction against the internal pressure of the reservoir air chamber R, and as shown by the solid line in FIG. The reaction force of the front fork during extension is reduced to zero, so that the rapid start of the contraction stroke is not hindered, and the ride comfort is not deteriorated.

  In addition, the case 16 including the lower spring receiver 4b includes a through hole 16a that communicates the upper and lower sides of the case 16, and does not hinder the movement of the hydraulic oil. Since the pressure acts below the case 16 through the through hole 16a, the entire extension working chamber P2 can be pressurized.

  The upper end of the balance spring 4 is preferably fixed to the upper spring receiver 4a. However, the present invention is not limited to this. Even if the lower end of the balance spring 4 is fixed to the lower spring receiver 4b, both ends are fixed. It may be used free of charge.

  Further, the balance spring 4 is fixed at the upper end side to the inner tube 2 via the partition member 5 and contacts the outer periphery with the inner periphery of the inner tube 2 while avoiding the sliding surface of the piston 15.

  Accordingly, the balance spring 4 is supported by the inner tube 2 to prevent buckling, and the lower end side of the balance spring 4 is in sliding contact with the inner periphery of the inner tube 2 only in the vicinity of the maximum extension of the fork main body on which the balance spring 4 operates.

  That is, the balance spring 4 is not slidably contacted with the inner periphery of the inner tube 2 except near the maximum extension of the fork main body, and the inner periphery of the inner tube 2 can be minimized.

  Further, the balance spring 4 abuts against the inner tube 2 avoiding the sliding surface of the piston 15, that is, in the present embodiment, the lower end of the balance spring 4 at the maximum extension is the inner tube 2 and the piston 15. The length is set so that it does not hit the sliding surface.

  By providing this configuration, the sliding surface of the piston 15 is not damaged by the expansion and contraction of the balance spring 4, and the friction when the outer periphery of the piston 15 comes into sliding contact with the inner periphery of the inner tube 2 is minimized. It is possible to ensure movement.

  Further, since the balance spring 4 abuts on the inner circumference of the inner tube 2, the coil diameter of the balance spring 4 can be maximized, the number of turns of the balance spring 4 can be minimized, and the overall length can be shortened.

  By the way, the rod 13 for holding the piston 15 includes a pair of upper and lower cushion members 17a and 17b attached to the outer periphery thereof. The upper cushion member 17a is in the vicinity of the proximal end member of the rod 13, and the lower cushion member 17b is It is attached to the approximate center of the rod 13.

  These cushion members 17a and 17b are made of an elastic material, and when the fork main body is fully extended, as shown in FIG. 1, the inner peripheral piece 5a of the partition wall member 5 to which the lower cushion member 17b is fixed to the inner tube 2 is provided. As shown in FIG. 2, the upper cushion member 17 a comes into contact with the upper surface of the inner peripheral piece 5 a of the partition member 5 when the fork main body is contracted most.

  Accordingly, each cushion member 17a, 17b absorbs an impact when the fork main body is most extended and contracted, and prevents further expansion and contraction.

  Even when the cushion member 17b and the partition member 5 are in contact with each other, the upper and lower reservoir air chambers R1 and R2 communicate with each other, and the cushion member 17b and the partition member 5 are in contact with the upper and lower reservoir air chambers R1 and R2. It will not prevent communication.

  A cap-shaped bottom case 23 made of a hard synthetic resin is fixed to the bottom member 22 on the lower side of the inner tube 2 in the figure. Although not shown, the outer periphery of the bottom case 23 and the bottom member 22 are sealed in a liquid-tight manner. An air chamber A communicating with the outside air is provided inside the bottom case 23.

  The bottom case 23 is formed in such a length that the upper end thereof and the piston 15 do not come into contact with each other when the fork main body is contracted as shown in FIG. It is possible to reduce the amount and reduce the weight of the front fork.

  Therefore, as long as the stroke length is secured, the fork main body may be shortened without providing the case 23.

  By providing the above configuration, the front fork in the present embodiment can exhibit basic performance as a front fork such as functions as an air suspension and a fluid pressure shock absorber.

  In addition, the front fork in the present embodiment has a configuration for smoothly projecting and retracting the inner tube 2 in the outer tube 1, and this configuration is embodied between the inner periphery of the outer tube 1 and the outer periphery of the inner tube 2. Is done.

  As shown in FIG. 3, the fork main body forms a cylindrical lubrication gap 3a between the inner circumference of the inner tube 1 and the outer circumference of the outer tube 2, and accommodates the working fluid for lubrication in the lubrication gap 3a.

  A pair of upper and lower annular bearings 6a and 6b are provided in the lubrication gap 3a, and the annular bearings 6a and 6b help the inner tube 2 to smoothly protrude into and out of the outer tube 1.

  An annular first seal member 11 slidably in contact with the outer periphery of the inner tube 2 is provided at the opening end 10 on the inner tube insertion side of the outer tube 1, that is, the inner periphery of the lower end in the figure, and this first seal member 11 is lubricated. The working oil is held in the lubrication gap 3a.

  The first seal member 11 includes an annular dust seal 11a located outside and an annular oil seal 11b provided in series inside the dust seal 11a, and a conventionally known configuration is employed.

  A second seal member 21 is provided in series with the first seal member 11, and the second seal member 21 is in sliding contact with the inner periphery of the outer tube 1 positioned on the inner side of the first seal 11. And the inner tube 2 are sealed.

  Therefore, the pressure inside the fork main body does not act on the lubrication gap 3a outside the second seal member 21, and even when the first seal member 11 is damaged, the lubricating hydraulic oil is ejected from the lubrication gap 3a. It becomes possible to prevent.

  Further, the inner circumference of the outer tube 1 positioned on the inner side of the first seal 11 is not exposed to the outside air, and is maintained smoothly because it is not damaged by an external factor such as a stepping stone.

  Accordingly, the sliding surface of the second seal member 21 is kept smooth, and it is possible to reliably function as a fail-safe while avoiding the risk of the second seal member 21 being damaged by scratches on the sliding surface.

  In the present embodiment, the lubricating gap 3a is sealed at the lower end side in the figure with the first seal member 11, and the upper end side in the figure is attached to the inner tube 2 via the partition member 5 in the second seal member. 21 and is expanded and contracted as the fork body expands and contracts.

  That is, as shown in FIG. 1, when the fork main body is in the extended state, the first seal member 11 and the second seal member 21 approach each other and the volume of the lubrication gap 3a contracts, as shown in FIG. In addition, when the fork main body is in the contracted state, the first seal member 11 and the second seal member 21 are separated from each other, and the volume of the lubrication gap 3a is expanded.

  The lubrication gap 3a communicates with the volume compensation chamber 3b via an oil hole 30 provided on the distal end side of the inner tube 2 in the figure, and constitutes an oil reservoir chamber 3 sealed together with the volume compensation chamber 3b.

  The oil reservoir 3 is partitioned from the inside of the fork main body by the second seal member 21, and when the fork main body is in the extended state, the inside thereof is located below and filled with the hydraulic fluid for lubrication. A lubricating oil chamber L and an air chamber G located above the oil level O1 of the lubricating oil chamber L are formed (FIGS. 1 and 3).

  By providing the configuration, when the fork main body is extended, the volume of the lubrication gap 3a is reduced, so that the hydraulic oil overflowing from the lubrication gap 3a flows into the volume compensation chamber 3b through the oil hole 30. (FIG. 1).

  Further, when the fork body contracts, the volume of the lubrication gap 3a increases, so that insufficient hydraulic oil in the lubrication gap 3a is supplied from the volume compensation chamber 3b into the lubrication gap 3a through the oil hole 30. (FIG. 2).

  And the increase / decrease in the hydraulic oil in the volume compensation chamber 3b is compensated by expansion / contraction of the gas accommodated in the air chamber G.

  By providing the above configuration, the pressure of the reservoir air chamber R inside the fork main body does not act on the oil reservoir 3 positioned outside the second seal member 21, and the oil reservoir 3 is partitioned from the inside of the fork main body. Thus, it is possible to prevent the pressure inside the fork main body from acting on the lubrication gap 3a.

  Furthermore, the oil level in the lubrication gap 3a is reduced by providing the volume compensation chamber 3b and forming the lubrication oil chamber L and the air chamber G in the oil reservoir chamber 3 composed of the lubrication gap 3a and the volume compensation chamber 3b. And the volume change of the lubrication gap 3a can be compensated.

  The volume compensation chamber 3b is formed by a cylindrical partition member 5 provided on the insertion side of the inner tube 2 into the outer tube 1, that is, on the inner side of one end located on the upper side in the drawing.

  As shown in FIG. 3, the partition member 5 protrudes from one end of the inner tube 2 and has an annular protrusion 50 provided with the second seal member 21 on the outer periphery, and extends from the protrusion 50. An annular coupling part 51 whose outer periphery is coupled to the inner circumference of one end of the inner tube 2, an annular reduced diameter part 52 extending from the coupling part 51 and having a reduced outer diameter, and the reduced diameter part 52 The outer periphery of the inner tube 2 is provided with a close contact portion 53 that is in liquid-tight contact with the inner periphery of the inner tube 2 via a seal member 53a.

  A volume compensation chamber 3 b is formed between the outer periphery of the reduced diameter portion 52 and the inner periphery of the inner tube 2, and the volume compensation chamber 3 b has the oil hole 30 in the lap portion with the reduced diameter portion 52 in the inner tube 2. It is opened and communicated with the lubrication gap 3 a through the oil hole 30.

  With the above configuration, when the front fork is assembled, the working fluid is filled up to the vicinity of the upper end while the fork member is maintained in the most contracted state, and then the partition member 5 is assembled to the inner tube 2, thereby Since the air chamber is naturally formed inside, the oil reservoir chamber 3 in the present embodiment can be easily realized.

  Further, since the second seal member 21 is attached to the partition wall member 5, the second seal member 21 can also be easily assembled.

  The second seal member 21 is provided in series with the air seal 21a facing the reservoir air chamber R to seal the gas sealed in the reservoir air chamber R, and in the lubricating gap 3a. And an annular oil seal 21b for sealing the working fluid.

  With this configuration, the seal 21a and 21b can reliably seal the gas in the reservoir air chamber R and the working fluid in the lubrication gap 3a.

  The characteristics of the seal used as the second seal member 21 can be appropriately selected depending on the object to be sealed.

    In addition, the oil seal 21b is not necessarily provided as long as the air seal 21a has a function of sealing the hydraulic oil in the lubrication gap 3a to the extent that the oil is not scraped into the reservoir air chamber R.

  By the way, in the present embodiment, a pair of upper and lower annular bearings 6a and 6b that facilitate smooth sliding between the outer tube 1 and the inner tube 2 are provided in the lubrication gap 3a, and the outer periphery of the upper end portion of the inner tube 2 in the figure. The upper annular bearing 6a is positioned on the inner periphery of the outer tube 1 and the lower annular bearing 6b is slidable.

  The upper annular bearing 6a is provided above the oil hole 30 that connects the lubrication gap 3a and the volume compensation chamber 3b, is fitted in a groove 24 formed on the outer periphery of the inner tube 2, and does not move. By being in sliding contact with the inner periphery of the outer tube 1 and having this configuration, the working fluid that moves between the lubrication gap 3a and the volume compensation chamber 3b is not hindered.

  On the other hand, the lower annular bearing 6b is slidably provided in a groove 10a formed on the inner periphery of the lower tip 10 of the outer tube 1 in the figure, and slides on the inner periphery of the inner tube 2 via an oil film. It contacts and moves up and down as the inner tube 2 moves.

  By providing the structure, it is possible to supply the working fluid to the oil seal 11b in the first seal member 11 to ensure the slidability of the oil seal 11b.

  The configuration for smoothly projecting and retracting the inner tube 2 in the outer tube 1 is not limited to the above, and the configurations of the seal members 11 and 21 and the annular bearings 6a and 6b can be selected as appropriate. It is.

  While the preferred embodiment of the present invention has been described above, it should be understood that modifications, variations and changes may be made without departing from the scope of the claims.

  For example, in the above-described embodiment, an inverted front fork is used. However, the present invention is not limited to this. It goes without saying that an upright front walk may be used.

  In the present embodiment, the configuration according to the present invention is embodied in the front fork. However, the present invention is not limited thereto, and may be embodied in a rear cushion unit or other suspension device.

  In the present embodiment, the working oil as the working fluid is stored in the fork main body. However, the present invention is not limited to this, and it is needless to say that the working fluid may be an aqueous working fluid.

  Further, although the lubricating fluid 3 is accommodated in the lubricating gap 3a, a hydraulic fluid other than the hydraulic fluid, for example, a hydraulic fluid or another hydraulic fluid may be used.

A Air chamber G Air chamber L Lubricating oil chamber O, O1 Oil level P1 Pressure side working chamber P2 Stretch side working chamber R Reservoir air chamber V1 Pressure side leaf valve V2 Stretch side leaf valve 1 Outer tube 2 Inner tube 3 Oil reservoir chamber 3a Lubrication gap 3b Volume compensation chamber 4 Balance spring 5 Partition members 6a and 6b Annular bearing 11 First seal member 12 Cap member 13 Rod 14 Tip member 15 Piston 16 Case 17 Cushion members 21 and 210 Second seal member 22 Bottom member 23 Bottom case

Claims (4)

A shock absorber body composed of an outer tube and an inner tube which is inserted and retracted into the outer tube, a working chamber made of a working fluid accommodated in the inner tube, and facing the working chamber and the buffer A reservoir air chamber that is made of gas sealed in the container body and maintains a pressure-increasing tendency and functions as an air spring, and moves inside the operating chamber while sliding the outer periphery on the inner periphery of the inner tube, and operates on the pressure side in the operating chamber A piston that is divided into a chamber and an extension-side working chamber, a rod that stands on the axial center of the outer tube and holds the piston, and a damping force generating means that generates a predetermined damping force as the piston moves With
Provided with a balance spring whose one end is fixed to the inner tube and whose outer periphery abuts on the inner tube inner periphery,
The balance spring suppresses a spring reaction force caused by the reservoir air chamber in a predetermined stroke range in which the shock absorber body contracts from a fully extended state.   The fluid pressure shock absorber according to claim 1, wherein the balance spring abuts on an inner periphery of the inner tube while avoiding a sliding surface of the piston. The pressure side working chamber is formed on the piston side, and the extension side working chamber is formed on the rod side.
The fluid pressure buffer according to claim 1 or 2, wherein the reservoir air chamber pressurizes the expansion side working chamber via the liquid level of the expansion side working chamber. The balance spring is interposed between one end of the inner tube located on the insertion side of the outer tube and the piston.
The balance spring urges one end portion of the inner tube to separate from the piston in a predetermined stroke range in which the shock absorber main body contracts from a fully extended state. 4. The fluid pressure buffer according to any one of 3.

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