JP2010101351A - Hydraulic shock absorber - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a hydraulic shock absorber capable of exerting a damping force having excellent responsibility even in a compression stroke. <P>SOLUTION: The hydraulic shock absorber includes: an outer tube 1; an inner cylinder 2 stored inside the outer tube 1; a partitioning member 3 forming a working chamber C in the inner cylinder 2 as well as forming a compensation chamber R in the outer cylinder 1; a piston 4 partitioning the working chamber C into a rod chamber R1 and a piston chamber R2; a rod 5 having one end connected to the piston 4; an extension side damping passage 6 provided in the piston 4 to permit a flow from the rod chamber R1 toward the piston chamber R2 and to apply resistance to the flow of liquid passing through; a pressure side damping passage 7 provided in the partition member 3 to permit the flow from the piston chamber R2 toward the compensation chamber R and to apply resistance to the flow of liquid passing through; a piston chamber side suction passage 8 permitting only the flow flowing from the compensation chamber R toward the piston chamber R2; and a rod side suction passage 9 permitting only the flow from the compensation chamber R toward the rod chamber R1. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a hydraulic shock absorber.

  In a single cylinder type hydraulic shock absorber, for example, a cylinder, a free piston that is slidably inserted into the cylinder and divides the inside of the cylinder into a liquid chamber and an air chamber, and a slidable within the cylinder. A piston that is inserted and divides the liquid chamber into a rod chamber and a piston chamber, and a rod that has one end connected to the piston, is configured to suppress vibration of the vibration control target (see, for example, Patent Document 1). .

  Also, in this hydraulic shock absorber, when the piston moves in the axial direction with respect to the cylinder and expands and contracts, the volume of the air chamber is expanded by changing the volume in the cylinder when the rod enters and exits the cylinder. Alternatively, it is compensated by decreasing.

  And this hydraulic shock absorber compresses the rod chamber where the piston does not face the air chamber in the extending stroke and enlarges the volume of the opposite piston chamber, so that the liquid flows from the rod chamber to the piston chamber, Resistance is given to the flow of this liquid, the pressure rise of a rod chamber is promoted, a difference is produced in the pressure of a piston chamber and a rod chamber, and the damping force which prevents expansion | extension is exhibited by making the said differential pressure act on a piston. On the other hand, the hydraulic shock absorber compresses the piston chamber facing the air chamber and expands the volume of the opposite rod chamber in the process of being compressed, so that the liquid is expanded from the piston chamber to the rod chamber. The pressure is applied to the flow of the liquid to create a difference in the pressure between the piston chamber and the rod chamber, and the differential pressure acts on the piston to exert a damping force that prevents compression.

  On the other hand, a multi-cylinder type hydraulic shock absorber has, for example, a cylinder, a piston that is slidably inserted into the cylinder and divides the cylinder into a rod chamber and a piston chamber, and one end connected to the piston. And an outer tube that covers the cylinder and forms a reservoir that communicates with the piston chamber between the cylinder and suppresses vibration of the vibration control target (see, for example, Patent Document 2). .

  Further, in this double cylinder type hydraulic shock absorber, when the piston is in the stroke of moving in the axial direction with respect to the cylinder and expanding and contracting, the volume of the rod entering the cylinder or the rod retracting from the cylinder. However, the excess or deficiency in the cylinder is compensated by supplying or absorbing the excess or deficient volume of liquid.

  In particular, during the compression stroke, the volume of the rod chamber expands and the volume of the piston chamber decreases, so that the flow of liquid flows between the flow from the piston chamber to the rod chamber and the flow from the piston chamber to the reservoir. Two flows occur.

  At this time, the liquid for the volume expansion of the rod chamber moves from the piston chamber to the rod chamber, and the liquid for the rod intrusion volume that becomes excessive in the cylinder is discharged from the piston chamber to the reservoir.

In the case of this hydraulic shock absorber, in order to exert a compression side damping force during the compression stroke, a resistance is mainly given to the flow of the liquid flowing out of the cylinder, and the pressure in the rod chamber and the piston chamber is increased to increase the piston chamber. A damping force is generated by the pressure receiving area difference between the piston chamber and the rod chamber, and the base valve is responsible for this pressure rise, giving resistance to the flow of liquid from the piston chamber to the reservoir, To increase the pressure.
JP 08-159199 A (FIG. 1) Japanese Patent Laid-Open No. 11-182610 (FIG. 1)

  As described above, the single-cylinder hydraulic shock absorber compresses the rod chamber that does not face the gas chamber during the extension stroke, so that the pressure in the rod chamber can be adjusted within the range that the oil seal around the rod allows. On the contrary, during the compression stroke, the piston chamber facing the gas chamber is compressed, so the pressure in the piston chamber does not exceed the pressure in the air chamber, and attenuation during the compression stroke There is a tendency for power to reach its peak.

  For this reason, the single-cylinder type hydraulic shock absorber is designed to enclose pressurized gas in the air chamber and maintain the liquid in the cylinder in a constantly pressurized state to increase the damping force during the compression stroke. However, if the pressure in the air chamber is increased, the pressure in the liquid chamber in the cylinder of the hydraulic shock absorber will increase, and this pressure will also act on the oil seal that seals around the rod. The tightening force increases, the sliding resistance of the rod becomes excessive, and the smooth expansion and contraction of the hydraulic shock absorber is hindered. Especially when used in a vehicle application, the vehicle occupant feels a jerky feeling. It can impede ride comfort.

  On the other hand, in a double cylinder type hydraulic shock absorber, the cylinder diameter cannot be increased because a reservoir is formed on the outer periphery, and the pressure in the cylinder is increased during the compression stroke to increase the pressure between the piston chamber and the rod chamber. Since the damping force is generated by the pressure receiving area difference, not only the piston chamber but also the rod chamber is compressed and the amount of compressed liquid is larger than that during the expansion stroke, and the damping force is displayed with good response during the compression stroke. It is difficult to let

  The reason for this is that the liquid is compressible because it contains gas, and in order to generate a damping force with good response during the compression stroke with a large amount of compressed liquid, the pressure inside the cylinder is increased by increasing the pressure in the cylinder. It is conceivable to increase the rigidity of the base valve and increase the resistance of the base valve.However, if this is done, the cylinder internal pressure will become too high and the oil seal that seals the outer periphery of the rod will There is a possibility that a new problem that the pressure is pressed and the smooth movement of the rod with respect to the cylinder is hindered may occur.

  As another method, instead of the piston-side check valve, a valve that provides resistance to the flow from the piston chamber to the rod chamber during the compression stroke is provided so that the pressure in the rod chamber is reduced. Although a method of generating a differential pressure between the two can be considered, if the pressure in the rod chamber is excessively reduced, a gas mixed in the compressed state in the liquid in the rod chamber causes aeration to appear as bubbles, There is a possibility that the responsiveness of the generation of the damping force of the hydraulic shock absorber is deteriorated.

  Therefore, the present invention was created to improve the above-described problems, and the object of the present invention is to provide a hydraulic shock absorber that can exhibit a damping force with good responsiveness even in the compression stroke. is there.

  In order to achieve the above object, the hydraulic shock absorber in the problem solving means of the present invention operates in the inner cylinder by closing the outer tube, the inner cylinder accommodated in the outer tube, and the end of the inner cylinder. A partition member that forms a chamber and forms a compensation chamber in the outer cylinder, a piston that is slidably inserted into the inner cylinder and divides the working chamber into a rod chamber and a piston chamber, and is movable into the inner cylinder A rod whose one end is connected to the piston, an extension side damping flow path which is provided on the piston and allows flow from the rod chamber to the piston chamber and provides resistance to the flow of liquid passing therethrough, and a partition member A pressure-side damping channel that is provided to allow a flow from the piston chamber toward the compensation chamber and to provide resistance to the flow of liquid passing therethrough; A piston chamber side suction passage for allowing only flow from the compensating chamber into the piston chamber, characterized by comprising a rod chamber side suction passage for allowing only flow from the compensating chamber to the rod chamber.

  According to the liquid shock absorber of the present invention, during the compression stroke, only the piston chamber is compressed and the pressure is increased to generate the compression side damping force, so that the pressure difference between the rod chamber and the piston chamber is increased. In addition, since the amount of compressed liquid is smaller than that of the conventional hydraulic shock absorber, the damping force on the compression side can be generated with good responsiveness. Also, during the compression stroke, the entire amount of liquid discharged from the piston chamber can be flowed to the compression side damping flow path, the pressure in the piston chamber can be greatly increased, and a large damping force compared to the conventional hydraulic pressure buffer Can also be generated.

  Further, in order to generate a damping force on the compression side with good response to the hydraulic shock absorber, it is necessary to increase the pressure in the rod chamber and the piston chamber in the inner cylinder, that is, the pressure in the cylinder, by greatly pressurizing the compensation chamber. Therefore, there is no problem that the seal member is strongly pressed to the rod side by the pressure in the inner cylinder to prevent the rod from moving.

  Furthermore, during the compression stroke, the rod chamber to be depressurized sucks liquid from the compensation chamber through the rod chamber side suction flow path, so that the rod chamber is excessively depressurized and aeration occurs, resulting in the damping force of the hydraulic shock absorber. The responsiveness of generation does not deteriorate, and undesirable phenomena such as cavitation and erosion are not caused.

  That is, this hydraulic shock absorber can generate a damping force on the compression side with good responsiveness during the compression stroke while avoiding the problems that occur in the conventional hydraulic shock absorber, and the practicality and reliability of the hydraulic shock absorber Will be improved.

  The present invention will be described below based on the embodiments shown in the drawings. FIG. 1 is a longitudinal sectional view of a hydraulic shock absorber according to an embodiment of the present invention.

  As shown in FIG. 1, the hydraulic shock absorber D of the present invention has an outer tube 1, an inner cylinder 2 accommodated in the outer tube 1, and an end portion of the inner cylinder 2 closed so as to be in the inner cylinder 2. A partition member 3 that forms a working chamber C and forms a compensation chamber R in the outer cylinder 1 and a slidable insertion in the inner cylinder 2 divide the working chamber C into a rod chamber R1 and a piston chamber R2. A piston 4, a rod 5 that is movably inserted into the inner cylinder 3 and has one end connected to the piston 4, and a liquid that is provided on the piston 4 and allows a flow from the rod chamber R 1 to the piston chamber R 2 and passes therethrough. The expansion side damping flow path 6 that provides resistance to the flow of the liquid and the partition member 3 that allows the flow from the piston chamber R2 toward the compensation chamber R and allows the liquid to pass therethrough. A pressure-side damping flow path 7 that provides resistance thereto, a piston chamber-side suction flow path 8 that allows only a flow from the compensation chamber R to the piston chamber R2, and a rod that allows only a flow from the compensation chamber R to the rod chamber R1. The chamber side suction flow path 9 is provided.

  More specifically, the inner cylinder 2 has a cylindrical shape and is accommodated in the outer tube 1. The piston 4 that is slidably inserted into the inner cylinder 2 allows liquid to enter the inner cylinder 2. A rod chamber R1 and a piston chamber R2 filled with a working hydraulic oil are formed. A rod 5 is movably inserted into the inner cylinder 2 and one end thereof is connected to the piston 4. In the present embodiment, the liquid is hydraulic oil, but is not limited to this, and other liquids may be used.

  The piston 4 is provided with a port 6a for communicating the rod chamber R1 and the piston chamber R2, and the outlet end of the port 6a is opened and closed by a leaf valve 6b stacked on the lower end of the piston 4 in FIG. It has come to be.

  The leaf valve 6b has a so-called outer opening in which the inner periphery is fixed by the rod 5 and the outer periphery is a free end. When the pressure of the rod chamber R1 is received through the port 6b, the outer periphery is bent to Open and give resistance to the flow of liquid passing through the port 6a, but if the pressure in the piston chamber R2 is greater than the pressure in the rod chamber R1, it is pressed against the port 6b, so that the port 6b is kept closed. . As described above, the port 6b is set to be one-way by the leaf valve 6b. In this embodiment, the expansion-side attenuation flow path 6 is formed by the port 6a and the leaf valve 6b.

  The extension-side attenuation flow path 6 allows the liquid to move from the compressed rod chamber R1 to the expanded piston chamber R2 during the expansion stroke of the hydraulic shock absorber D, and resists the passage of the liquid. To cause a predetermined pressure loss to increase the pressure in the rod chamber R1 and function as a damping force generating element that generates a damping force on the extension side. In the above description, the leaf valve 6b provides resistance to the liquid flow. However, a damping valve having another structure such as a throttle valve or a poppet valve may be used.

  An outer tube 1 that is longer than the inner cylinder 2 and covers the inner cylinder 2 is provided outside the inner cylinder 2. An annular gap is provided between the outer tube 1 and the inner cylinder 2. 10 is formed.

  And the rod guide 11 which pivotally supports the rod 5 is fitted by the inner periphery of the upper end in FIG. 1 of this outer tube 1, and the upper end of the outer tube 1 is obstruct | occluded. The rod guide 11 is provided with a cylindrical socket 11a on the outer periphery of the lower end in FIG. 1, and the upper end of the inner cylinder 2 is inserted into the socket 11a. It is supposed to be blocked. The rod guide 11 is annular so that the rod 5 can be pivotally supported, and a notch 11b is provided between the bottom and the socket 11a. The rod chamber R1 is communicated with the annular gap 10 through the notch 11b. . In the above description, the notch 11b is provided in the rod guide 11 for communication between the annular gap 10 and the rod chamber R1, but a hole may be provided in place of the notch 11b to communicate these. A notch or a hole may be provided at the upper end of the inner cylinder 2. Further, a seal member 18 that seals between the rod 5 and the outer tube 1 is laminated above the rod guide 11 to prevent liquid leakage from the outer tube 1 and the inner cylinder 2.

  Further, a partition wall member 3 fixed to the inner periphery of the outer tube 1 is fitted to the lower end of the inner cylinder 2, and the lower end of the inner cylinder 2 is closed. The partition member 3 forms a compensation chamber R on the lower side in the outer tube 1. Specifically, the partition member 3 is provided at the upper end in FIG. 1 and is fitted with the lower end of the inner cylinder 2. A port 3b that is provided on the outer periphery from 3a and communicates between the compensation chamber R and the annular gap 10, and two ports 3c and 3d that open from the upper end of the convex portion 3a and communicate between the compensation chamber R and the piston chamber R2. It has.

  The outer tube 1 includes a tube main body 1a facing the inner cylinder 2, and a bottomed cylindrical extension cylinder 1b which is connected to the tube main body 1a and forms a compensation chamber R. The extension cylinder 1b is the upper end in FIG. 1 has an enlarged diameter portion 1c into which the lower end in FIG. 1 serving as one end of the partition member 3 and the tube main body 1a is inserted. In the case of this embodiment, a screw portion is provided on the outer periphery of the tube main body 1a, and the tube main body 1a is inserted into the enlarged diameter portion 1c of the extension cylinder 1b together with the partition wall member 3 so that the inner circumference of the enlarged diameter portion 1c. The tube body 1a and the extension cylinder 1b are integrated, and the partition wall member 3 is sandwiched between the tube body 1a and the extension cylinder 1b and fixed to the outer tube 1.

  By configuring the outer tube 1 in this way, the partition member 3 can be easily installed at the intermediate portion of the outer tube 1 and the assembling property is improved. However, the outer tube 1 is not necessarily connected to the tube body 1a and the extension tube. It is not necessary to be composed of only two parts 1b, and it may be composed of three or more parts or a single part.

  Then, the partition member 3 is fixed to the outer tube 1 configured as described above, the inner cylinder 2 is inserted together with the rod guide 11 and the seal member 18, and the cap 12 is screwed onto the outer periphery of the upper end of the outer tube 1. As a result, the inner cylinder 2 is sandwiched between the rod guide 11 and the partition wall member 3 and fixed to the outer tube 1. When the cap 12 is not used, the rod guide 11 and the seal member 18 may be fixed to the outer tube 1 by crimping the upper end of the outer tube 1.

  An annular check valve 13 for opening and closing the upper end of the port 3 c is stacked on the upper end of the partition member 3, and an annular leaf valve 14 for opening and closing the lower end of the port 3 d is stacked on the lower end of the partition member 3. The inner periphery of the leaf valve 14 is fixed to a guide rod 19 penetrating the center of the partition member 3, and only the outer periphery is allowed to be bent. The check valve 13 includes a through hole 13a so as not to close the port 3d.

  An annular check valve 15 is mounted on the outer periphery of the convex portion 3 a of the partition wall member 3, and the check valve 15 is inserted by inserting the convex portion 3 a of the partition wall member 3 into the inner periphery of the lower end of the inner cylinder 2. The inner circumference is sandwiched between the partition wall member 3 and the inner cylinder 2. Accordingly, the check valve 15 is fixed at the inner peripheral side as described above to be a fixed end, and the outer periphery is allowed to flex freely and is set as a free end, and is provided on the outer periphery of the convex portion 3a. The upper end opening end of the port 3b is opened and closed.

  In this way, the annular check valve 15 is mounted on the outer periphery of the convex portion 3 a of the partition wall member 3 and is sandwiched between the partition wall member 3 and the lower end of the inner cylinder 2. There is an advantage that the check valve 15 can be incorporated without affecting the axial length.

  A free piston 16 is slidably inserted in the inner periphery of the extension cylinder 1b. The free piston 16 fills the compensation chamber R with a liquid chamber L and gas at a predetermined pressure. The air chamber G is divided. Furthermore, a bracket 17 that allows the hydraulic shock absorber D to be attached to a vehicle or the like is provided at the bottom of the extension cylinder 1b that is the lower end of the outer tube 1. In addition, a gas injection hole 1d that allows gas to be filled into the air chamber G is provided on the bottom side of the extension cylinder 1b. The injection hole 1d is closed, and the air chamber G is kept airtight. Therefore, in the hydraulic pressure buffer D in this embodiment, the pressure in the compensation chamber R can be easily adjusted by supplying and discharging gas to and from the gas chamber G through the gas injection hole 1d. The damping force generation responsiveness can be adjusted by adjusting the pressure in the compensation chamber R. If there is no need for the adjustment, the gas injection hole 1d may be closed by a plug or the like that cannot be removed.

  In the illustrated example, the hydraulic shock absorber D is set up in a so-called upright type in which the rod 5 is disposed above and the inner cylinder 2 is disposed below, but the rod 5 is disposed below and the inner cylinder 2 is disposed. In the case of the so-called inverted type in which 2 is arranged upward, the free piston 16 can be omitted, but by providing the free piston 16, the gas into the rod chamber R1 and the piston chamber R2 There is an advantage that the intrusion of can be reliably prevented.

  The liquid chamber L communicates with the piston chamber R2 at the port 3c and the port 3d, and communicates with the annular gap 10 at the port 3b. The check valve 13 that opens and closes the port 3c bends when the pressure in the compensation chamber R is received through the port 3c, opens the port 3c, and connects the liquid chamber L and the piston chamber R2. When the pressure exceeds the pressure in the compensation chamber R, the port 3c is closed to prevent the flow of liquid from the piston chamber R2 toward the liquid chamber L. The port 3c is one-way by the check valve 13. In this embodiment, the piston chamber side suction flow path 8 is formed by the port 3 c and the check valve 13.

  The leaf valve 14 that opens and closes the port 3d bends when the pressure of the piston chamber R2 is received through the port 3d, opens the port 3d, and connects the piston chamber R2 and the liquid chamber L to pass through the port 3d. On the contrary, when the pressure in the compensation chamber R exceeds the pressure in the piston chamber R2, the port 3d is closed to prevent the liquid flow from the liquid chamber L toward the piston chamber R2. The port 3d is set to be one-way by the leaf valve 14, and in this embodiment, the compression-side damping flow path 7 is formed by the port 3d and the leaf valve 14.

  The pressure-side attenuation flow path 7 allows the liquid to move from the piston chamber R2 to be compressed to the compensation chamber R during the compression stroke of the hydraulic pressure buffer D, and provides resistance to the passage of the liquid to give a predetermined amount. It functions as a damping force generating element that generates pressure loss and increases the pressure in the piston chamber R2 to generate a damping force on the compression side. In the above description, the leaf valve 14 provides resistance to the liquid flow, but a damping valve having another structure such as a throttle valve or a poppet valve may be used.

  Further, the check valve 15 that opens and closes the port 3b bends when receiving the pressure of the compensation chamber R through the port 3b, opens the port 3b, and causes the liquid chamber L and the annular gap 10 to communicate with each other. When the pressure of 10 exceeds the pressure of the compensation chamber R, the port 3b is closed to prevent the liquid flow from the annular gap 10 toward the liquid chamber L. As described above, the port 3b is set to be one-way by the check valve 15, and the annular gap 10 is communicated with the rod chamber R1 as described above. Therefore, in this embodiment, the port 3b is checked with the port 3b. The rod chamber side suction flow path 9 is formed by the valve 15 and the annular gap 10.

  The compensation chamber R described above supplies the inner cylinder 2 with a volume of liquid that retreats from the inner cylinder 2 of the rod 5 that is insufficient in the inner cylinder 2 when the hydraulic buffer D is extended. During compression, the liquid corresponding to the volume of the rod 5 entering the inner cylinder 2 that is excessive in the inner cylinder 2 is supplied to the inner cylinder 2, thereby performing volume compensation. .

  In the hydraulic shock absorber D configured as described above, in the extension stroke in which the piston 4 is displaced upward in FIG. 1 with respect to the inner cylinder 2, the rod chamber R1 is compressed and the piston chamber R2 is expanded. The liquid moves from the rod chamber R1 to the piston chamber R2 through the expansion side attenuation flow path 6, and the liquid of the volume of the rod 5 that retreats from the inner cylinder 2 flows from the compensation chamber R to the piston chamber side suction flow path 8. To the piston chamber R2. During this extension stroke, the pressure in the rod chamber R1 rises, so the check valve 15 closes the port 3b, so that the rod-side suction flow path 9 is closed, and the liquid passes only through the extension-side attenuation flow path 6. Moving.

  At this time, the extension side damping flow path 6 gives resistance to the flow of the liquid passing therethrough, so that a predetermined pressure loss occurs, the pressure in the rod chamber R1 is increased, and there is a large difference between the rod chamber R1 and the piston chamber R2. Pressure is generated, and a damping force on the extension side is generated. In addition, when a damping valve is provided in the middle of the piston chamber side suction flow path 8 or when the check valve 13 is set to have a high bending rigidity and the check valve 13 provides resistance to the liquid flow, the piston chamber R2 Since the pressure is greatly reduced, the damping force during the extension stroke can be increased as compared with the case without the damping valve.

  On the other hand, in the compression stroke in which the piston 4 is displaced downward in FIG. 1 with respect to the inner cylinder 2, the piston chamber R2 is compressed and the rod chamber R1 is enlarged. Here, in this hydraulic shock absorber D, the volume of liquid that decreases as the rod 5 is displaced downward from the piston chamber R2 to be compressed moves to the compensation chamber R via the compression side damping channel 7. To do. The hydraulic shock absorber D also includes a rod chamber side suction passage 9 that allows only the flow from the compensation chamber R to the rod chamber R1, and the check valve 15 is provided by the pressure reduction of the rod chamber R1. Since the port 3b is opened, the rod 5 is displaced downward and the volume of liquid that is insufficient in the cylinder 1 is supplied from the compensation chamber R to the rod chamber R1 via the rod chamber side suction flow path 9.

  The pressure-side damping flow path 7 provides resistance to the flow of liquid passing therethrough, resulting in a pressure loss. Further, since the liquid is supplied from the compensation chamber R to the rod chamber R1, there is a problem with the hydraulic pressure buffer D. In contrast, during the compression stroke, unlike the conventional double-cylinder hydraulic shock absorber in which both the rod chamber R1 and the piston chamber R2 are compressed, only the piston chamber R2 is increased in pressure and a compression-side damping force is generated. It will be. When a damping valve is provided in the middle of the rod chamber side suction flow path 9 or when the check valve 15 is set to have a high bending rigidity and resistance is given to the flow of liquid by the check valve 15, the rod chamber R1 Since the pressure is greatly reduced, the damping force during the compression stroke can be increased as compared with the case without the damping valve.

  Thus, the above-described hydraulic pressure buffer D compresses and increases only the piston chamber R2 during the compression stroke to generate a compression-side damping force, so that the rod chamber R1 and the piston chamber R2 The pressure difference can be increased, and the amount of compressed liquid is reduced as compared with the conventional multi-cylinder type hydraulic shock absorber, so that the compression side damping force can be generated with good responsiveness. Further, during the compression stroke, the entire amount of liquid discharged from the piston chamber R2 can be flowed to the compression side damping flow path 7, and the pressure in the piston chamber R2 can be greatly increased, compared with the conventional hydraulic pressure buffer. A large damping force can be generated.

  In addition, in order to generate a pressure-side damping force in the hydraulic shock absorber D with good responsiveness, the pressure in the compensation chamber R is greatly increased and the pressure in the rod chamber R1 and the piston chamber R2 in the inner cylinder 2, that is, the pressure in the cylinder. Therefore, there is no problem that the seal member 18 is strongly pressed by the pressure in the inner cylinder 2 toward the rod 5 to prevent the rod 5 from moving.

  Further, during the compression stroke, the rod chamber R1 to be decompressed sucks liquid from the compensation chamber R through the rod chamber side suction flow path 9, so that the rod chamber R1 is excessively decompressed to generate aeration, thereby hydraulic pressure buffering. The responsiveness of the generation of the damping force of the vessel is not deteriorated, and undesirable phenomena such as cavitation and erosion are not caused.

  In other words, the hydraulic shock absorber D can generate the damping force on the compression side with good responsiveness during the compression stroke while avoiding the problems that occur in the conventional hydraulic pressure shock absorber. Reliability will be improved.

  Note that in the hydraulic shock absorber D, the piston 4 is provided with an extension / attenuation channel that communicates the rod chamber R1 and the piston chamber R2 in parallel with the extension-side attenuation channel 6 and provides resistance to the flow of the passing liquid. You may make it provide in. Until the leaf valve 6b in the expansion side attenuation flow path 6 and the leaf valve 14 in the compression side attenuation flow path 7 are opened while the piston speed is in the low speed region, the above expansion pressure attenuation flow path is preferentially liquid. Is set so as to pass through, the damping characteristic when the piston speed when the hydraulic shock absorber D expands and contracts is in the low speed region can be determined by the expansion and damping flow path.

  Further, in parallel with the piston side suction flow path 8, the compensation chamber R and the piston chamber R <b> 2 may be communicated and a second pressure side attenuation flow path that provides resistance to the flow of the passing liquid may be provided. If the piston speed is in the low speed region and the leaf valve 14 in the compression side attenuation channel 7 is opened, the second pressure side attenuation channel is set to pass liquid preferentially. The damping characteristic when the piston speed when the hydraulic shock absorber D is compressed is in the low speed region can be determined by the second pressure side damping flow path.

  Further, in parallel with the rod side suction flow path 9, a second extension side attenuation flow path that communicates the compensation chamber R and the rod chamber R 1 and provides resistance to the flow of the passing liquid may be provided. Then, until the leaf speed 6b in the extension side attenuation flow path 6 is opened when the piston speed is in the low speed region, the second extension side attenuation flow path is set so as to pass liquid preferentially. In this case, the damping characteristic when the piston speed when the hydraulic shock absorber D extends is in the low speed region can be determined by the second extension side damping flow path. In addition, the 2nd compression side attenuation | damping flow path and the 2nd expansion | extension side attenuation | damping flow path can be specifically installed in the partition member 3, for example.

  As described above, the upper limit of the low speed region of the piston speed that preferentially passes through the compression / attenuation passage, the second compression / attenuation passage, and the second extension / side attenuation passage can be arbitrarily set. In addition, if the hydraulic shock absorber D is applied to a general four-wheeled vehicle, it may be set to an arbitrary value of 0.2 m / s or less, and a damping characteristic suitable for the four-wheeled vehicle can be realized.

  Further, in the present embodiment, the above-described extension-side damping channel 6 and compression-side damping channel 7 cannot change the damping force, but a variable damping valve can be provided to change the damping force. It may be.

  This is the end of the description of the embodiment of the present invention, but the scope of the present invention is of course not limited to the details shown or described.

It is a longitudinal cross-sectional view of the hydraulic pressure buffer in one embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Outer tube 1a Tube main body 1b Extended cylinder 1c Expanded diameter part 1d Gas injection hole 2 Inner cylinder 3 Partition member 3a Projection part 3b, 3c, 3d in a partition member Port 4 Piston 5 Rod 6 Extension side damping flow path 6a Port 6b, 14 Leaf valve 7 Pressure side damping flow path 8 Piston chamber side suction flow path 9 Rod chamber side suction flow path 10 Annular gap 11 Rod guide 11a Socket 11b Notch 12 Cap 13, 15 Check valve 13a Through hole 16 Free piston 17 Bracket 18 Seal member 19 Guide rod 20 Plug C Working chamber D Hydraulic buffer G Gas L Liquid chamber R Compensation chamber R1 Rod chamber R2 Piston chamber

Claims (7)

An outer tube, an inner cylinder housed in the outer tube, a partition member that closes the end of the inner cylinder to form a working chamber in the inner cylinder and forms a compensation chamber in the outer cylinder, and an inner cylinder A piston that slidably inserts into the rod chamber and the piston chamber, a rod that is movably inserted into the inner cylinder and has one end connected to the piston, and a rod chamber that is provided in the piston. An extension-side damping flow path that allows the flow from the piston chamber to the piston chamber and resists the flow of the liquid that passes through, and the flow of the liquid that passes through the partition member and allows the flow from the piston chamber to the compensation chamber. Pressure side damping flow path that provides resistance, and piston chamber side suction flow path that allows only flow from the compensation chamber to the piston chamber Hydraulic shock absorber characterized by comprising a rod chamber side suction passage which permits flow only toward the rod chamber from the compensation chamber. 2. The hydraulic shock absorber according to claim 1, wherein a rod chamber side suction flow path is formed by an annular gap between the outer tube and the inner cylinder. The outer tube includes a tube main body facing the inner cylinder, and an extension cylinder connected to the tube main body and forming a compensation chamber, and the extension cylinder has an enlarged diameter in which a partition wall member and one end of the tube main body are inserted into an end portion. 3. The hydraulic shock absorber according to claim 1, wherein the partition wall member is sandwiched between the tube main body and the extension cylinder. The partition member includes a convex portion that fits into the inner cylinder, and a port that communicates the compensation chamber and the rod chamber side suction flow channel on the outer periphery of the convex portion. 4. The hydraulic shock absorber according to claim 2, further comprising an annular check valve that is fixed to an outer opening and that opens and closes the port. 5. The hydraulic shock absorber according to claim 1, further comprising a second pressure-side damping flow path arranged in parallel with the piston chamber-side suction flow path. The hydraulic shock absorber according to any one of claims 1 to 5, further comprising a second extension side damping flow path arranged in parallel with the rod chamber side suction flow path. The hydraulic shock absorber according to any one of claims 1 to 6, wherein the piston is provided with an expansion / attenuation flow path communicating the rod chamber and the piston chamber.

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