JP2011174501A - Multi-cylinder hydraulic shock absorber - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a multi-cylinder hydraulic shock absorber capable of overcoming a shortage of damping force at a low expansion operation speed and at an initial stage of expansion operation. <P>SOLUTION: A check valve 8 is provided at a midpoint in a reflux passage 7 for refluxing a liquid collected in a liquid sump chamber A between a rod guide 5 and a seal material 6 via a clearance between the rod guide 5 and a rod 3 to a reservoir R and the valve is not opened when expansion operation speed is below 0.2 m/sec. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a double cylinder type hydraulic shock absorber.

  In general, a multi-cylinder type hydraulic shock absorber includes a rod guide that closes the opening end of the cylinder and the opening end of the outer cylinder covering the cylinder and supports a rod that is movably inserted into the cylinder. The rod guide is laminated with an annular insert metal having a seal member on each of the inner periphery and the outer periphery to keep the hydraulic shock absorber oil-tight.

  Specifically, the insert metal is provided with an annular seal that contacts the inner periphery of the outer cylinder on the outer peripheral side, and a seal lip and a dust lip that are in sliding contact with the outer periphery of the rod are provided on the inner peripheral side. Is sealed with an insert metal.

  In such a double cylinder type hydraulic shock absorber, the rod and the rod guide are not completely sealed, so the rod guide and the insert are interposed between the rod and the rod guide. It flows into the oil reservoir between the metal. As hydraulic oil flows into the oil reservoir chamber, the pressure in the oil reservoir chamber increases, but the pressure in the oil reservoir chamber acts on the seal lip and presses the seal lip against the outer periphery of the rod. Because the friction between the seal lip and the rod is generated to prevent the rod from moving in the axial direction, the communication hole that connects the oil reservoir chamber and the reservoir formed between the cylinder and the outer cylinder The hydraulic oil in the oil reservoir chamber is allowed to escape to the reservoir.

  However, if the oil reservoir chamber and the reservoir communicate with each other without limitation, there is a risk of gas entering the cylinder from the reservoir side. An annular valve body made of rubber, which is called a check seal that allows the seal, is seated on the upper surface of the rod guide.When the check seal is closed, communication between the reservoir and the oil reservoir chamber is prevented. When the internal pressure increases, the check seal is opened and the oil reservoir chamber is communicated with the reservoir so that the working oil is returned from the oil reservoir chamber to the reservoir (see, for example, Patent Document 1).

Japanese Patent Laid-Open No. 2001-311446

  By the way, when the double cylinder type hydraulic shock absorber generally exhibits a contraction operation, the rod enters the cylinder and the hydraulic oil in the rod enters excessively in the cylinder. The cylinder is discharged to the reservoir through a base valve provided at the end of the cylinder and provided in a partition member that partitions the piston side chamber and the reservoir. Is raised to generate a compression side damping force. Further, the double cylinder type hydraulic shock absorber exerts an extension side damping force by the pressure increase of the rod side chamber during the extension operation.

  On the other hand, in the conventional double cylinder type hydraulic shock absorber, the increase in the pressure in the oil sump chamber leads to an increase in the tightening force of the seal lip that seals the outer periphery of the rod, thus preventing the rod from moving. The valve opening pressure of the seal is made as small as possible to prevent the pressure in the oil reservoir chamber from increasing.

  As described above, in the conventional double cylinder type hydraulic shock absorber, the valve opening pressure of the check seal is set as small as possible, so that the valve opens as soon as the pressure in the cylinder rises and the pressure propagates to the oil reservoir. As a result, the hydraulic oil escapes to the reservoir. Therefore, in the conventional double cylinder type hydraulic shock absorber, when the expansion / contraction operation is performed, the check seal is opened from the initial stage of the expansion / contraction operation, and the pressure in the cylinder escapes to the reservoir, preventing the pressure increase in the cylinder. Therefore, there is a place where the damping force is insufficient particularly when the expansion / contraction operation speed is at a very low speed of less than 0.2 m / sec (meter per second) or at the initial stage of the expansion / contraction operation.

  Therefore, the present invention was devised in order to improve the above-described problems, and the object of the present invention is to solve the shortage of damping force when the expansion / contraction operation speed is at a very low speed or at the initial stage of the expansion / contraction operation. It is to provide a possible double cylinder type hydraulic shock absorber.

  In order to solve the above-described object, the problem-solving means in the present invention includes a cylinder, a piston that is slidably inserted into the cylinder and is divided into a rod-side chamber and a piston-side chamber filled with liquid, and a piston. A rod that is movably inserted into the cylinder and connected to the piston, an outer cylinder disposed on the outer peripheral side of the cylinder, and an annular gap between the cylinder and the outer cylinder, is communicated with the piston side chamber. In addition, a reservoir filled with gas and liquid, a rod guide for closing the outer cylinder and the end of the cylinder and supporting the rod slidably, and a rod guide laminated between the rod and the outer cylinder. The liquid that has entered the liquid storage chamber between the rod guide and the seal member is returned to the reservoir through the seal member to be sealed and the gap between the rod guide and the rod. In a multi-cylinder hydraulic shock absorber provided with a flow passage and a check valve provided in the middle of the reflux passage, the check valve allows only the flow of liquid from the liquid reservoir chamber to the reservoir and at least during expansion / contraction operation. If the piston speed is less than 0.2 m / sec, the valve is not opened.

  According to the double cylinder type hydraulic shock absorber of the present invention, since the check valve does not open at least when the piston speed during expansion / contraction operation is less than 0.2 m / sec, the expansion / contraction operation speed is very low or the expansion / contraction operation initial stage. In addition, it is possible to prevent the pressure in the cylinder from escaping to the reservoir through the check valve, and it is possible to solve the shortage of damping force when the expansion / contraction operation speed is very low or at the initial stage of the expansion / contraction operation.

  In addition, when the piston speed during expansion / contraction operation is very low or when the damping force is expected to be sufficiently generated in the initial stage of expansion / contraction operation, for example, a suspension interposed between a vehicle body and an axle in a vehicle The multi-cylinder hydraulic shock absorber of the present invention is optimal for use, can generate a damping force firmly when changing lanes, etc., and can improve the riding comfort in the vehicle.

It is a longitudinal cross-sectional view of the double cylinder type hydraulic shock absorber in one embodiment. It is a partial expanded longitudinal cross-sectional view of the head part of the double cylinder type hydraulic shock absorber in one embodiment.

  Hereinafter, the double cylinder type hydraulic shock absorber of the present invention will be described with reference to the drawings. As shown in FIG. 1, a double cylinder type hydraulic shock absorber according to an embodiment includes a cylinder 1 and a rod side chamber R1 that is slidably inserted into the cylinder 1 and filled with liquid. Piston 2 partitioned into a piston side chamber R2, a rod 3 movably inserted into the cylinder 1 and connected to the piston 2, an outer cylinder 4 disposed on the outer peripheral side of the cylinder 1, a cylinder 1 and an outer cylinder 4 is formed in an annular gap between the reservoir 4 and is connected to the piston side chamber R2 and is filled with a gas and a liquid, closes the end of the outer cylinder 4 and the cylinder 1 and slides the rod 3 freely. A rod guide 5 pivotally supported on the rod, a seal member 6 laminated on the rod guide 5 to seal between the rod 3 and the outer cylinder 4, and a rod guide 5 via a gap between the rod guide 5 and the rod 3. And seal A liquid reservoir chamber recirculation passage recirculates liquid has entered the A to the reservoir R 7 between the timber 6 is constructed by a check valve 8 which is provided in the middle of the recirculation passage 7.

  Hereinafter, each member will be described in detail. The cylinder 1 has a cylindrical shape, a rod guide 5 into which the rod 3 is slidably inserted is fitted at the upper end, and the upper end of the cylinder 1 is closed. A partition member 9 is fitted to the lower end of the cylinder 1, and the lower end of the cylinder 1 is closed by the partition member 9.

  Thus, the cylinder 1 is closed at the upper end and the lower end by the rod guide 5 and the partition member 9, respectively, and the cylinder 2 is slidably inserted into the cylinder 1 so that the inside of the cylinder 1 is the upper rod side chamber in FIG. The rod-side chamber R1 and the piston-side chamber R2 are filled with a liquid such as hydraulic oil.

  Further, the piston 2 is attached to the tip which is the lower end in FIG. 1 of the rod 3 which is movably inserted into the cylinder 1, and has ports 2a and 2b which communicate with the rod side chamber R1 and the piston side chamber R2. is doing.

  The port 2a of the piston 2 is provided with a check valve 11 that allows only the flow of liquid from the piston side chamber R2 to the rod side chamber R1, and the port 2b of the piston 2 is provided with a rod side chamber R1 to the piston side chamber R2. A damping valve 12 is provided that allows only the flow of liquid to the front and provides resistance to the flow of liquid passing therethrough.

  An outer cylinder 4 is provided outside the cylinder 1 so as to cover the cylinder 1 and form an annular gap with the cylinder 1 and close the lower end in FIG. Is formed. The reservoir R is filled with a liquid, and an inert gas as a gas is filled upward along the liquid level S with the liquid. When closing the lower end of the outer cylinder 4, a lid may be provided to close the outer cylinder 4, or the outer cylinder 4 may be formed in a bottomed cylinder in advance.

  The rod guide 5 has an annular shape, and is provided so that the convex portion 13 protrudes downward from the lower end in FIG. 1, and the convex portion 13 fits into the opening end that is the upper end in FIG. The upper end of the cylinder 1 is closed. Further, the rod guide 5 is inserted on the inner peripheral side of the opening end which is the upper end in FIG. 1 of the outer cylinder 4 and closes the upper end of the outer cylinder 4, that is, the upper end of the reservoir R is also the rod guide 5. It is blocked by

  Further, a cylindrical bearing 14 is mounted on the inner periphery of the rod guide 5, and the rod 3 is slidably inserted into the bearing 14, and the upper end of the rod 3 in FIG. ing.

  Further, a concave portion 15 and a step portion 16 connected to the outer peripheral portion of the concave portion 15 are provided on the inner peripheral side of the upper end in FIG. 1 of the rod guide 5, and the rod guide 5 opens to the reservoir R of the rod guide 5 as desired. A through hole 17 is provided to communicate with the outer periphery of the lower end.

  Subsequently, an annular seal member 6 is laminated on the upper end side of the rod guide 5 in FIG. The seal member 6 is provided on the outer peripheral side of an annular insert metal 18 laminated on the rod guide 5, an inner peripheral lip 19 provided on the inner peripheral side of the insert metal 18 and in sliding contact with the outer periphery of the rod 3. An outer peripheral seal 20 that is in close contact with the inner periphery of the outer cylinder 4 and a check valve 8 provided at the cylinder side end that is the lower end of the insert metal 18 in FIG. 1 are provided to seal between the rod 3 and the outer cylinder 4. This prevents leakage of liquid from the double cylinder type hydraulic shock absorber.

  The sealing member 6 is fixed to the outer cylinder 4 while being pressed against the rod guide 5 side by crimping the opening end of the outer cylinder 4 to the inner peripheral side, and the opening ends of the cylinder 1 and the outer cylinder 4. The cylinder 1 and the outer cylinder 4 are maintained in a sealed state.

  As described above, when the insert metal 5 is laminated on the rod guide 5, a liquid reservoir chamber A is formed between the insert metal 18 and the recess 15 provided on the upper surface side of the rod guide 5 in FIG. 1. In the liquid reservoir A, when the double cylinder type hydraulic shock absorber expands and contracts, it adheres to the outer periphery of the rod 3 and is located above the rod guide 5 through a sliding gap between the rod 3 and the bearing 14. The passed liquid is scraped off by the inner peripheral lip 19 and collected in the liquid storage chamber A.

  The liquid reservoir chamber A communicates with the reservoir R through a through hole 17 provided in the rod guide 5, and in this case, the reflux passage 7 has a gap and a passage between the insert metal 18 and the rod guide 5. It is formed by the holes 17.

  In this case, the check valve 8 is annular and is a rubber check seal provided on the lower surface of the insert metal 18 in FIG. 1 and FIG. Until the pressure in the liquid reservoir chamber A reaches the valve opening pressure, it contacts the step portion 16 to shut off the reflux passage 7 and, conversely, in the liquid reservoir chamber A. When the pressure reaches the valve opening pressure, it leaves the step portion 16 to open the reflux passage 7 and connect the liquid reservoir chamber A to the reservoir R.

  Specifically, the check valve 8 has its own stepping force in a state where the tip side, which is the rod guide 5 side, has a larger diameter than the root side integrated with the insert metal 18 and is bent toward the outer peripheral side. Is set so as not to open when the piston speed is less than 0.2 m / sec when the double cylinder type hydraulic shock absorber is expanded and contracted by being pressed against and contacted to the step portion 16 by an initial load. Has been.

  That is, the check valve 8 receives the pressure in the liquid reservoir chamber A from the front side and the gas pressure of the reservoir R from the rear side, and the pressure in the liquid reservoir chamber A and the pressure in the reservoir R The valve opens when the pressure difference reaches the valve opening pressure, but the pressure difference between the pressure in the liquid reservoir A and the pressure in the reservoir R when the piston speed is 0.2 m / sec is opened. The valve pressure is set to open when the piston speed is 0.2 m / sec or more.

  Subsequently, a partition member 9 is fitted and sealed at the lower end of the cylinder 1, and the reservoir R and the piston side chamber R <b> 2 are partitioned by the partition member 9. The partition member 9 is sandwiched and fixed between the bottom end of the outer cylinder 4 and the cylinder 1. That is, in the case of this embodiment, the partition member 9, the cylinder 1, the rod guide 5 and the seal member 6 are inserted into the outer cylinder 4 in this order, and the upper end opening end in FIG. Each member inserted into the outer cylinder 4 is fixed to the outer cylinder 4 by caulking toward the side.

  The partition member 9 is provided with a suction passage 21 that communicates the reservoir R and the piston-side chamber R2, and a discharge passage 22 that similarly communicates the reservoir R and the piston-side chamber R2. The suction passage 21 is provided with a check valve 23 that allows only the flow of liquid from the reservoir R to the piston side chamber R2, and the discharge passage 22 has only a flow of liquid from the piston side chamber R2 to the reservoir R. And a damping valve 24 is provided which provides resistance to the flow of liquid passing therethrough.

  As described above, the multi-cylinder hydraulic shock absorber is configured, and the operation will be described. When the double cylinder type hydraulic shock absorber is extended, the piston 2 moves upward in FIG. 1, the pressure in the upper rod side chamber R1 in the figure rises, and the liquid in the rod side chamber R1 becomes piston 2 It moves to piston side chamber R2 via port 2b. When the liquid moves, the damping valve 12 provided at the port 2b gives resistance, so that a differential pressure is generated between the rod side chamber R1 and the piston side chamber R2, and the double cylinder type hydraulic shock absorber has an extension side damping force that suppresses the extension operation. appear. Further, since the rod 3 is retracted from the cylinder 1, the check valve 23 is opened, and the liquid deficient in the cylinder 1 is supplied from the reservoir R into the cylinder 1 through the suction passage 21 of the partition member 9.

  In the expansion operation of the double cylinder type hydraulic shock absorber, as described above, even if the pressure in the rod side chamber R1 rises and propagates into the liquid reservoir chamber A, the check valve 8 is at the piston speed during the expansion operation. Is less than 0.2 m / sec, the valve is not opened, so that the pressure in the rod side chamber R1 is quickly increased, and there is no case where the extension speed is very low or the damping force is insufficient in the initial stage of the extension operation.

  On the contrary, when the double cylinder type hydraulic shock absorber is contracted, the piston 2 moves downward in FIG. 1, so the volume in the upper rod side chamber R1 in the figure decreases, but the rod 3 By penetrating into the cylinder 1, the liquid corresponding to the rod penetrating volume becomes excessive in the cylinder 1.

  In this case, the check valve 11 is opened and the pressures in the rod side chamber R1 and the piston side chamber R2 become substantially equal, but excess liquid is discharged to the reservoir R via the discharge passage 22, and this discharge is performed. Since the damping valve 24 provides resistance to the flow of the liquid passing through the passage 22, the pressure in the cylinder 1 is increased, and the double-cylinder type hydraulic pressure buffer has a difference between the pressure in the cylinder 1 and the pressure receiving area in the piston 2. Accordingly, a compression side damping force that suppresses the contraction operation is generated.

  In the contraction operation of the double cylinder type hydraulic shock absorber, as described above, even if the pressure in the cylinder 1 rises and propagates into the liquid reservoir A, the check valve 8 has a piston speed during the contraction operation. Since the valve is not opened at less than 0.2 m / sec, the pressure in the cylinder 1 is quickly increased, and there is no case where the contraction speed is very low or the damping force is insufficient at the initial stage of the contraction operation.

  In other words, the check valve 8 is set so as not to open when the piston speed during expansion / contraction operation is less than 0.2 m / sec, so that the expansion / contraction operation speed is slightly lower than that of the conventional double cylinder type hydraulic shock absorber. In this case, it is possible to prevent the pressure in the cylinder from escaping to the reservoir through the check valve at the initial stage of the expansion / contraction operation, and it is possible to eliminate the deficiency of the damping force when the expansion / contraction operation speed is very low or at the initial stage of the expansion / contraction operation.

  In addition, when the piston speed during expansion / contraction operation is very low or when the damping force is expected to be sufficiently generated in the initial stage of expansion / contraction operation, for example, a suspension interposed between a vehicle body and an axle in a vehicle The multi-cylinder hydraulic shock absorber of the present invention is optimal for use, can generate a damping force firmly when changing lanes, etc., and can improve the riding comfort in the vehicle.

  Furthermore, if the check valve 8 is set to open when the piston speed during expansion / contraction operation of the double cylinder type hydraulic shock absorber is 0.2 m / sec or more, even if air accumulates in the rod side chamber R1, There are many opportunities for the double cylinder type hydraulic shock absorber to expand and contract at a speed of 0.2 m / sec or more due to vibration input during traveling of the vehicle, and there is no fear that air cannot be discharged to the reservoir R.

  Although the check valve 8 is a check seal provided on the seal member 6 in the above description, the check valve 8 is not limited to this, and a check valve may be provided in place of the check seal or connected in series with the check seal. Alternatively, a check valve may be provided. Various known structures can be adopted as the structure of the check valve 8. For example, a check valve made of an annular plate is fitted on the outer periphery of the convex portion 13 of the rod guide 5, and the check valve 8 The inner circumference may be sandwiched between the cylinder 1 and the rod guide 5, and the opening of the through hole 17 facing the reservoir R may be opened and closed by the check valve. However, the check seal is generally provided in a double-cylinder hydraulic shock absorber, and the above-described effects can be obtained without adding new parts by setting the check seal as described above using the check valve 8 as a check seal. Is economically advantageous.

  As described above, the check valve 11 is provided in the port 2 a provided in the piston 2, but this may be changed to a damping valve, or a check valve 23 is provided in the suction passage 21 in the partition member 9. However, this may be changed to a damping valve, and it is also possible to employ a configuration in which a port allowing bidirectional flow is provided in the piston 2 or the partition member 9 and a damping valve is provided in the port. It is.

 This is the end of the description of the multi-cylinder hydraulic shock absorber of the present invention, but the scope of the present invention is not limited to the details shown or described.

  The present invention can be used for a double cylinder type hydraulic shock absorber.

DESCRIPTION OF SYMBOLS 1 Cylinder 2 Piston 2a, 2b Port 3 Rod 4 Outer cylinder 5 Rod guide 6 Seal member 7 Reflux passage 8 Check valve 9 Partition member 11 Check valve 12 Damping valve 13 Convex part 14 in the rod guide 15 Bearing 15 Concave part 16 in the rod guide Rod guide Step portion 17 in the rod guide 18 Insert metal 19 in the seal member 19 Inner peripheral lip 20 in the seal member Outer seal 21 in the seal member Suction passage 22 Discharge passage 23 Check valve 24 Damping valve A Reservoir chamber R Reservoir R1 Rod side chamber R2 Piston side chamber S Liquid level

Claims (2)

A cylinder, a rod slidably inserted into the cylinder and filled with liquid in the cylinder, a piston partitioning the piston into a chamber, and a rod movably inserted into the cylinder and connected to the piston An outer cylinder disposed on the outer peripheral side of the cylinder, a reservoir formed by an annular gap between the cylinder and the outer cylinder, communicated with the piston side chamber and filled with gas and liquid, and an outer cylinder and a cylinder A rod guide that closes the end and pivotally supports the rod, a seal member that is stacked on the rod guide and seals between the rod and the outer cylinder, and a gap between the rod guide and the rod. A multi-cylinder type having a recirculation passage for returning the liquid that has entered the liquid storage chamber between the rod guide and the seal member to the reservoir, and a check valve provided in the middle of the recirculation passage In the pressure buffer, the check valve allows only the flow of liquid from the liquid reservoir to the reservoir, and does not open at least when the piston speed during expansion and contraction is less than 0.2 m / sec. Mold hydraulic pressure buffer. The seal member is provided with an annular insert metal laminated on the rod guide, and the check valve is provided on the insert metal to check the opening and closing of the return passage by bringing the tip portion into contact with the rod guide in a detachable manner. The double cylinder type hydraulic shock absorber according to claim 1, wherein the double cylinder type hydraulic shock absorber is a seal.

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