JP2009052703A - Damping force adjustable hydraulic shock absorber - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To adjust extension side damping force and compression side damping force by simple structure in a damping force adjustable hydraulic shock absorber. <P>SOLUTION: In this damping force adjustable hydraulic shock absorber, a piston rod 21 is provided with an extension side back pressure inlet passage 52 for guiding the pressure of a rod side chamber 12A to an extension side back pressure chamber 51 on the back side of an extension side damping valve 33 and a compression side back pressure inlet passage 62 for guiding the pressure of a piston side chamber 12B to a compression side back pressure chamber 61 on the back side of a compression side damping valve 34. The hydraulic shock absorber includes a pressure control valve 70 for controlling each pressure of the extension side back pressure chamber 51 and the compression side back pressure chamber 61 by releasing the pressure in the extension back pressure chamber and the pressure in the compression side back pressure chamber 61 to the piston side chamber 12B and the rod side chamber 12A, respectively when each pressure in the extension side back pressure chamber 51 an din the compression side back pressure chamber 61 reaches an optional preset pressure, thereby adjusting the extension side damping force and the compression side damping force, respectively. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a damping force adjusting hydraulic shock absorber.

As described in Patent Document 1, as a damping force adjustment type hydraulic shock absorber, a piston rod is inserted into a cylinder, and the inside of the cylinder is divided into a rod side chamber and a piston side chamber by a piston fixed to the piston rod. A damping force adjusting type connected to each other via an extension side flow path provided on the piston, an extension side damping valve for opening and closing the extension side flow path, and a pressure side flow path and a pressure side damping valve for opening and closing the pressure side flow path. In the hydraulic shock absorber, an extension side back pressure chamber and a pressure side back pressure chamber are provided on the back side of the extension side damping valve on the extension side flow path and on the back side of the pressure side damping valve on the pressure side flow path, respectively. A bypass passage that bypasses the extension side flow path and the pressure side flow path of the piston and connects the rod side chamber and the piston side chamber is provided, and the extension back pressure chamber and the pressure side back pressure chamber are connected to the middle part of the bypass path. There are things. This bypass passage allows the flow of oil from the piston side chamber via the first check valve and allows the flow of oil from the rod side chamber via the second check valve. In addition, a pressure control valve for controlling the pressure in the extension side back pressure chamber and the pressure side back pressure chamber is provided in the relief chamber communicating with the bypass passage, and only the flow of oil from the relief chamber of the pressure control valve to the rod side chamber is allowed. And a fourth check valve that allows only the flow of oil from the relief chamber of the pressure control valve to the piston side chamber. In the damping force adjustment type hydraulic shock absorber described in Patent Document 1, when the set pressure of the pressure control valve is low, both the extension side damping force and the compression side damping force are low, and when the set pressure of the pressure control valve is high, the extension is performed. Both the side damping force and the compression side damping force are increased.
JP-A-8-4818

  In the damping force adjustment type hydraulic shock absorber described in Patent Document 1, a pressure control valve is provided in a bypass passage provided in the piston rod, and the bypass passage is connected to a passage communicating with each of the piston side chamber and the rod side chamber. Check valves, and the third and fourth check valves must be provided in the passages that connect the relief chamber of the pressure control valve to each of the rod side chamber and the piston side chamber. It is complicated.

  An object of the present invention is to adjust an extension side damping force and a compression side damping force with a simple structure in a damping force adjusting hydraulic shock absorber.

  According to the first aspect of the present invention, a piston rod is inserted into a cylinder, and a piston fixed to the piston rod divides the inside of the cylinder into a rod side chamber and a piston side chamber. In the damping force adjustment type hydraulic shock absorber that is communicated via the expansion side damping valve that opens and closes the expansion side flow path, and the pressure side flow path and the pressure side attenuation valve that opens and closes the pressure side flow path, An extension side back pressure chamber and a pressure side back pressure chamber are provided on the back side with respect to the extension side flow path and the back side with respect to the pressure side flow path of the compression side damping valve, respectively, and the extension for guiding the rod side chamber pressure to the extension side back pressure chamber is provided. Piston rods are provided with a side back pressure introduction path and a pressure side back pressure introduction path for guiding the pressure of the piston side chamber to the pressure side back pressure chamber, and the respective pressures of the extension side pressure chamber and the pressure side back pressure chamber are arbitrarily set pressures. Reached Sometimes, the pressure control valves that relieve the pressure in the extension side back pressure chamber and the pressure side back pressure chamber respectively to the piston side chamber and the rod side chamber and control the pressure in the extension side back pressure chamber and the pressure side back pressure chamber, respectively. Each of the extension side damping force and the compression side damping force can be adjusted.

  According to a second aspect of the present invention, in the first aspect of the present invention, the piston side further includes an extension-side back pressure relief path that communicates with the extension-side back pressure introduction path and a pressure-side back pressure relief path that communicates with the compression-side back pressure introduction path. The extension side back pressure relief path and the pressure side back pressure relief path are opened with respect to the piston side chamber and the rod side chamber, respectively, by the pressure control valve.

  According to a third aspect of the present invention, in the second aspect of the present invention, the extended-side back pressure relief path and the compressed-side back pressure relief path are a common relief path, and the common relief path is a small-diameter path connected to the extended-side back pressure introduction path. The pressure control valve has a stepped shaft shape consisting of a small diameter portion on the distal end side and a large diameter portion on the proximal end side, and the distal end surface of the small diameter portion is a common relief. The stepped valve seats of the small diameter path and the large diameter path can be brought into contact with and separated from each other, and the step surfaces of the large diameter section and the small diameter section are made to face the large diameter path of the common relief path.

  According to a fourth aspect of the present invention, in any one of the first to third aspects of the present invention, each of the extension-side back pressure chamber and the compression-side back pressure chamber includes a valve stopper for each of the extension-side damping valve and the compression-side damping valve. The backup collars are formed on the outer periphery of these valve stoppers, and each backup collar is urged by a spring to each of the expansion side damping valve and the compression side damping valve, and the expansion side damping valve has a pressure receiving area facing the extension side flow path. The pressure receiving area facing the expansion side back pressure chamber is made larger than the pressure receiving area facing the pressure side flow passage, and the pressure side damping valve is made larger than the pressure receiving area facing the pressure side back pressure chamber.

  According to a fifth aspect of the present invention, in the invention according to any one of the first to fourth aspects, the pressure control valve is a proportional solenoid pressure control valve.

(Claim 1)
(a) An extension side back pressure chamber and a pressure side back pressure chamber are provided on the back side of the extension side damping valve on the extension side flow path and the back side of the compression side damping valve on the pressure side flow path, respectively. The piston rod is provided with an expansion side back pressure introduction path for guiding the pressure of the rod side chamber and a pressure side back pressure introduction path for guiding the pressure of the piston side chamber to the compression side back pressure chamber. When each pressure reaches an arbitrary set pressure, the pressure in the expansion side back pressure chamber and the pressure side back pressure chamber are relieved to the piston side chamber and the rod side chamber, respectively, and the expansion side back pressure chamber and the pressure side back pressure chamber are relieved. It has a pressure control valve that controls the pressure of each of them, making it possible to adjust each of extension side damping force and compression side damping force. By adjusting the set pressure of the pressure control valve with a simple structure using the pressure control valve, the stretching / pressure damping force can be directly controlled regardless of the piston speed. The number of processing steps and assembly steps for the component parts are not increased, and it is simplified.

(Claim 2)
(b) The extension-side back pressure relief path and the pressure-side back pressure relief path for relief of the respective pressures in the extension-side back pressure chamber and the pressure-side back pressure chamber are respectively connected to the extension-side back pressure introduction path and the compression-side back pressure introduction path. These relief paths can be easily formed in the piston rod by communicating with each other.

(Claim 3)
(c) Since the extension side back pressure relief path and the pressure side back pressure relief path are shared as a common relief path, these relief paths can be easily formed on the piston rod.

  (d) The common relief path is a stepped hole formed of a small diameter path connected to the expansion side back pressure introduction path and a large diameter path connected to the compression side back pressure introduction path, and the pressure control valve is connected to the small diameter section on the distal end side and the proximal end side. A stepped shaft consisting of a large diameter part is formed, and the tip surface of the small diameter part can be contacted and separated from the small relief path of the common relief path and the stepped valve seat of the large diameter path, and the step surface of the large diameter part and the small diameter part is connected to the common relief path. I tried to face a large path. The relief characteristics of the pressure in the extension-side back pressure chamber can be set by the pressure receiving area where the tip surface of the small diameter portion of the pressure control valve faces the small diameter path of the common relief path. The pressure relief characteristics of the pressure side back pressure chamber can be set by the pressure receiving area where the step surface of the large diameter portion and the small diameter portion of the pressure control valve faces the large diameter path of the common relief path. The relationship between the expansion side damping force and the compression side damping force can be adjusted by the correlation between the pressure receiving area of the tip surface of the small diameter portion of the pressure control valve and the pressure receiving area of the step surface of the large diameter portion and the small diameter portion of the pressure control valve.

(Claim 4)
(e) Each of the expansion-side back pressure chamber and the compression-side back pressure chamber is formed by a valve stopper for each of the expansion-side damping valve and the compression-side damping valve and a backup collar provided on the outer periphery of each valve stopper. Is urged by the spring to each of the expansion side damping valve and the pressure side damping valve. The expansion side damping valve makes the pressure receiving area facing the expansion side flow path larger than the pressure receiving area facing the expansion side back pressure chamber, and the pressure side damping valve is the compression side The pressure receiving area facing the flow path was made larger than the pressure receiving area facing the compression side back pressure chamber. Therefore, when the relief pressure is set high, when the pressure in the expansion side flow path and the expansion side back pressure chamber rises during the expansion side stroke, the expansion side back pressure chamber is caused by the difference in the pressure receiving area of the expansion side damping valve. The upper side backup collar is pushed down, the extension side damping valve backed up by this backup color is opened, and the upper limit (maximum damping force) of the extension side damping force can be set. In addition, when both the pressure side flow path and the pressure side back pressure chamber rise in the pressure side stroke, the pressure collar on the pressure side back pressure chamber side is pushed down due to the difference in the pressure receiving area of the pressure side damping valve. The backup pressure side damping valve can be opened to set the upper limit (maximum damping force) of the compression side damping force.

(Claim 5)
(f) By setting the pressure control valve to be a proportional solenoid pressure control valve, the set pressure of the pressure control valve can be adjusted by changing the energization current to the proportional solenoid, and according to the energization current to the proportional solenoid. A predetermined damping force can be generated regardless of the piston speed.

  1 is a cross-sectional view showing a damping force adjusting hydraulic shock absorber, FIG. 2 is a cross-sectional view showing the damping force adjusting structure of FIG. 1, and FIG. 3 shows an extension side stroke of the damping force adjusting hydraulic shock absorber. Is a cross-sectional view showing a non-relief state of the extension side back pressure, (B) is a cross-sectional view showing a relief state of the extension side back pressure, FIG. 4 shows a compression side stroke of the damping force adjusting type hydraulic shock absorber, (A) is Cross-sectional view showing a non-relief state of compression side back pressure, (B) is a cross-sectional view showing a relief state of compression side back pressure, FIG. 5 shows the operation of the pressure control valve, and (A) shows an extension side back pressure relief state. Sectional drawing and (B) are sectional drawings which show a compression side back pressure relief state.

  As shown in FIGS. 1 and 2, the damping force adjusting hydraulic shock absorber 10 is a double-tube type composed of a double tube in which a cylinder 12 is built in a damper tube 11, and a piston rod 13 is inserted into the cylinder 12 to An axle side attachment portion is provided at the lower portion of the tube 11, and a vehicle body side attachment portion 14 is provided at the upper portion of the piston rod 13 to constitute a vehicle suspension device.

  The hydraulic shock absorber 10 has a suspension spring 16 interposed between a lower spring seat 15 on the outer periphery of the damper tube 11 and an upper spring seat (not shown) provided on the vehicle body side mounting portion 14 at the upper end portion of the piston rod 13. To do.

  The hydraulic shock absorber 10 clamps a rod guide 17, a bush 18, and an oil seal 19 for the piston rod 13 inserted into the cylinder 12 between the upper end crimped portion 11 </ b> A of the damper tube 11 and the upper end portion of the cylinder 12. It is fixed.

  The damping force adjusting hydraulic shock absorber 10 has a piston valve device 20 and a bottom valve device 40, and the damping force generated by them controls vibrations of the piston rod 13 due to the absorption of the impact force by the suspension spring 16. To do.

(Piston valve device 20)
The piston valve device 20 has a piston bolt 21 that is screwed and fixed to the outer periphery of the insertion end of the piston rod 13 into the cylinder 12, and a spacer 22, a valve stopper 23, a piston 24, a valve on the outer periphery of the piston bolt 21. The stopper 25 and the spacer 26 are inserted, and these are clamped and fixed between the base end step portion of the piston bolt 21 by a nut 27 screwed to the piston bolt 21.

  The piston 24 is provided with an expansion-side flow path 31 and a pressure-side flow path 32, and the annular central portion of the disk valve-shaped expansion-side damping force valve 33 is sandwiched between the piston 24 and the valve stopper 25. The annular central portion of the pressure-side damping valve 34 having a disc valve shape is sandwiched between the two. That is, the piston valve device 20 divides the inside of the cylinder 12 into a rod side chamber 12A and a piston side chamber 12B by a piston 24. The rod side chamber 12A and the piston side chamber 12B are provided with an extension side channel 31 provided in the piston 24 and the extension side channel. The expansion side damping valve 33 that opens and closes 31, the pressure side flow path 32, and the pressure side attenuation valve 34 that opens and closes the pressure side flow path 32 communicate with each other.

  Therefore, at the time of extension, the pressure oil in the rod side chamber 12A passes through the extension side flow path 31 of the piston 24, bends and opens the extension side damping valve 33, is guided to the piston side chamber 12B, and generates an extension side damping force. . Further, at the time of compression, the pressure oil in the piston side chamber 12B passes through the pressure side flow path 32 of the piston 24, bends and deforms the pressure side damping valve 34, and is led to the rod side chamber 12A to generate a pressure side damping force.

(Bottom valve device 40)
In the hydraulic shock absorber 10, a gap between the damper tube 11 and the cylinder 12 is defined as a reservoir chamber 12C, and the interior of the reservoir chamber 12C is partitioned into an oil chamber and a gas chamber. The bottom valve device 40 includes a bottom piece 41 that partitions the piston side chamber 12B and the reservoir chamber 12C inside the cylinder 12 between the lower end portion of the cylinder 12 and the bottom portion of the damper tube 11, and the bottom portion of the damper tube 11. The space between the bottom piece 41 and the bottom piece 41 can be communicated with the reservoir chamber 12C through a flow path provided in the bottom piece 41.

  The bottom valve device 40 includes a disk valve 42 and a check valve 43 as bottom valves for opening and closing a pressure side channel 41A and an extension side channel (not shown) provided in the bottom piece 41, respectively.

  At the time of extension, the oil corresponding to the retraction volume of the piston rod 13 retreating from the cylinder 12 pushes the check valve 43 open, and enters the piston side chamber 12B from the reservoir chamber 12C via the expansion side flow path (not shown) of the bottom piece 41. To be replenished. During compression, the oil corresponding to the volume of the piston rod 13 entering the cylinder 12 is opened from the piston side chamber 12B through the pressure side flow path 41A of the bottom piece 41 by bending and deforming the disk valve 42 and pushed into the reservoir chamber 12C. Get the compression side damping force.

  In the hydraulic shock absorber 10, the piston rod 13 is stretched around the piston rod 13 positioned in the rod side chamber 12 </ b> A of the cylinder 12 and on the rebound seat 46 fixed to the piston 24 side (upper side). A rebound rubber 47 that is compressed and deformed at the time (the maximum extension state of the hydraulic shock absorber 10) is provided.

  However, the hydraulic shock absorber 10 includes a damping force adjusting device 50 for adjusting the extension / pressure damping force of the piston valve device 30 as follows.

  As shown in FIG. 2, the damping force adjusting device 50 includes an extension side back pressure chamber on each of the back side of the extension side damping valve 33 with respect to the extension side channel 31 and the back side of the compression side damping valve 34 with respect to the pressure side channel 32. 51 and a compression side back pressure chamber 61 are provided. The expansion side back pressure introduction passage 52 that leads the pressure of the rod side chamber 12A to the extension side back pressure chamber 51 and the compression side back pressure introduction passage 62 that leads the pressure of the piston side chamber 12B to the compression side back pressure chamber 61 are respectively connected to the piston bolt 21 and the valve. The stopper 23, the piston 24, and the valve stopper 25 are provided. The extension-side back pressure introduction path 52 includes an introduction path 52A composed of a hole provided in the valve stopper 25 and an inner circumferential annular groove, an introduction path 52B composed of a horizontal hole, a vertical hole, and a horizontal hole provided in the piston bolt 21, and a piston. The inlet passage 52A having an inner circumferential annular groove and a hole provided in 24 and communicating with the rod side chamber 12A through the introduction passages 52B and 52C. In the present embodiment, the introduction path 52 </ b> C communicates with the rod side chamber 12 </ b> A through the extension side flow path 31. The pressure side back pressure introduction path 62 includes an introduction path 62A including a hole provided in the valve stopper 23 and an inner circumferential annular groove, an introduction path 62B including a horizontal hole, a vertical hole, and a horizontal hole provided in the piston bolt 21, and a piston 24. An introduction path 62C formed of an inner circumferential annular groove and a hole provided in the cylinder and communicating with the piston side chamber 12B via the introduction paths 62B and 62C. In the present embodiment, the introduction path 62 </ b> C communicates with the piston side chamber 12 </ b> B via the pressure side flow path 32.

  In this embodiment, each of the expansion side back pressure chamber 51 and the pressure side back pressure chamber 61 includes valve stoppers 25 and 23 provided on the back surfaces of the expansion side damping valve 33 and the pressure side damping valve 34, respectively, and these valve stoppers 25 and 23. Are formed by backup collars 53 and 63 provided so as to slide through O-rings 25A and 23A, and each backup color is provided by leaf springs 54 and 64 (springs) provided on the back surfaces of the backup collars 53 and 63. The front surfaces of 53 and 63 are urged and pressed against the extension side damping valve 33 and the compression side damping valve 34, respectively. An annular central portion of the annular leaf spring 54 is clamped and fixed between the valve stopper 25 and the spacer 26, and an outer edge portion of the leaf spring 54 comes into contact with the back-up collar 53 in an elastic bent state. An annular central portion of the annular leaf spring 64 is clamped and fixed between the valve stopper 23 and the spacer 22, and an outer edge portion of the leaf spring 64 comes into contact with the backup collar 63 in an elastic bent state. At this time, the pressure receiving areas that the expansion side damping valve 33 and the compression side attenuation valve 34 respectively face the expansion side flow path 31 and the pressure side flow path 32 face the expansion side back pressure chamber 51 and the pressure side back pressure chamber 61, respectively. Make it larger than the pressure receiving area.

  When the respective pressures in the expansion side back pressure chamber 51 and the compression side back pressure chamber 61 reach arbitrary set pressures, the damping force adjusting device 50 has the respective pressures in the expansion side back pressure chamber 51 and the compression side back pressure chamber 61. Are provided in the piston side chamber 12B and the rod side chamber 12A, respectively, and have pressure control valves 70 for controlling the respective pressures in the extension side back pressure chamber 51 and the pressure side back pressure chamber 61. Make each adjustable.

  In the present embodiment, the extension-side back pressure relief path 80 </ b> A communicating with the extension-side back pressure introduction path 52 (introduction path 52 </ b> B) connected to the extension-side back pressure chamber 51 as described above and the compression-side back pressure chamber 61 are connected to each other. The piston bolt 21 is provided with a pressure side back pressure relief path 80B that communicates with the pressure side back pressure introduction path 62 (introduction path 62B) connected as described above. In this embodiment, the extension-side back pressure relief path 80A communicates with the piston-side chamber 12B via a part (62B, 62C) of the pressure-side back pressure introduction path 62 and the pressure-side flow path 32. The compression side back pressure relief path 80 </ b> B communicates with the rod side chamber 12 </ b> A via a part (52 </ b> B, 52 </ b> C) of the expansion side back pressure introduction path 52 and the expansion side flow path 31. The pressure control valve 70 opens so that the extension-side back pressure relief path 80A and the pressure-side back pressure relief path 80B are electrically connected to the piston side chamber 12B and the rod side chamber 12A, respectively.

  In this embodiment, the extension side back pressure relief path 80A and the pressure side back pressure relief path 80B are a common relief path 80. The common relief path 80 is in the form of a vertical hole drilled in the center of the piston bolt 21, and is connected to a small diameter path 81 (FIG. 5) that is partly conjoined with the extension-side back pressure introduction path 52 (introduction path 52B). The pressure side back pressure introduction path 62 (introduction path 62B) has a stepped hole shape composed of a large diameter path 82 (FIG. 5) that is partially joined together. The pressure control valve 70 includes a solenoid 71 built in the proximal end portion of the piston bolt 21 and a valve body 72 inserted into the large diameter path 82 of the common relief path 80 from a hollow portion surrounded by the solenoid 71 of the piston bolt 21. Have The valve body 72 of the pressure control valve 70 has a stepped shaft shape composed of a small-diameter portion 72A on the distal end side and a large-diameter portion 72B on the proximal end side, and the conical distal end surface of the small-diameter portion 72A has a small-diameter path 81 of the common relief path 80. And a step-side valve seat 83 (FIG. 5) of the large-diameter path 82, and a step-side surface of the small-diameter portion 72A and the large-diameter portion 72B is the large-diameter path 82 of the common relief path 80. Let it come to 62.

  As the pressure control valve 70, a proportional solenoid pressure control valve can be adopted, which generates a constant thrust according to the energization current to the solenoid 71, and the set pressure can be arbitrarily adjusted by changing the energization current.

  In this embodiment, a spring 73 is provided between the end surface of the piston rod 13 and the base end flange surface of the valve body 72 of the pressure control valve 70 in the hollow portion surrounded by the solenoid 71 of the piston bolt 21. The valve body 72 of the pressure control valve 70 is urged in the valve closing direction in which the distal end surface of the small diameter portion 72A is in contact with the stepped valve seat 83 by the spring force of the spring 73, and in the valve closing direction by energizing the solenoid 71. The thrust of is given.

  The valve body 72 of the pressure control valve 70 may be biased in the valve closing direction by the spring force of the spring 73, or in the valve opening direction by the energization thrust to the solenoid 71, or may be opened by the spring force of the spring 73. The valve may be biased in the valve closing direction by an energizing thrust to the solenoid 71.

The damping force adjusting device 50 operates as follows.
(A) Stretch side stroke (Figs. 3 and 5)
The pressure oil in the rod side chamber 12A passes through the extension side flow path 31 of the piston 24, bends and deforms and opens the extension side damping valve 33, is guided to the piston side chamber 12B, and generates an extension side damping force.

  At this time, as shown by an arrow A in FIG. 3A, the pressure oil in the rod side chamber 12A passes from the extension side flow path 31 of the piston 24 through the extension side back pressure introduction path 52 such as the piston bolt 21 and the like. It is introduced into the pressure chamber 51. As a result, the pressure in the rod side chamber 12A is introduced into the extension side back pressure chamber 51 (A in FIG. 5A), and the extension side damping valve 33 is urged in the valve closing direction.

  Here, the pressure in the extension-side back pressure chamber 51 (the pressure receiving area S1 where the tip surface of the small diameter portion 72A of the valve body 72 of the pressure control valve 70 faces the small diameter path 81 of the common relief path 80 (FIG. 5A)). ) Reaches the set pressure of the pressure control valve 70 (the sum of the thrust generated by energizing the solenoid 71 and the spring force of the spring 73), as shown by the arrow B in FIG. Is retracted from the stepped valve seat 83, and the pressure in the extension side back pressure chamber 51 is the common relief path 80 (the extension side back pressure introduction path 52 and the extension side back pressure relief path 80A, the pressure side back pressure introduction path 62, and the pressure side flow path. 32) to the piston side chamber 12B (B in FIG. 5A). Therefore, the pressure in the extension side back pressure chamber 51 can be arbitrarily set by adjusting the set pressure of the pressure control valve 70 by the energization current to the solenoid 71.

  As a result, the expansion side damping valve 33 is bent and opened to a position where the pressure of the rod side chamber 12A in the expansion side flow path 31 and the elastic force of the expansion side attenuation valve 33 and the pressure of the expansion side back pressure chamber 51 are balanced. The extension side damping force is determined. Therefore, a desired extension side damping force is generated according to the energization current to the solenoid 71 regardless of the piston speed.

(B) Compression side stroke (Figs. 4 and 5)
The pressure oil in the piston side chamber 12B passes through the pressure side flow path 32 of the piston 24, bends and deforms and opens the pressure side damping valve 34, and is guided to the rod side chamber 12A to generate a pressure side damping force.

  At this time, the pressure oil in the piston side chamber 12B passes through the pressure side back pressure introduction passage 62 such as the piston bolt 21 from the pressure side flow path 32 of the piston 24 as shown by an arrow A in FIG. To be introduced. As a result, the pressure in the piston side chamber 12B is introduced into the pressure side back pressure chamber 61 (A in FIG. 5B), and the pressure side damping valve 34 is urged in the valve closing direction.

  Here, the pressure in the pressure-side back pressure chamber 61 (the pressure receiving area S2 in which the step surfaces of the small diameter portion 72A and the large diameter portion 72B of the valve body 72 of the pressure control valve 70 face the large diameter path 82 of the common relief path 80 (FIG. 5). When the load acting on (B)) reaches the set pressure of the pressure control valve 70 (the sum of the thrust generated by energizing the solenoid 71 and the spring force of the spring 73), as shown by the arrow B in FIG. The valve body 72 is retracted from the stepped valve seat 83, and the pressure in the pressure side back pressure chamber 61 is reduced to the common relief path 80 (the pressure side back pressure introduction path 62 and the pressure side back pressure relief path 80B, the extension side back pressure introduction path 52 and the extension). Relief is made to the rod side chamber 12A through the side flow path 31) (B in FIG. 5B). Therefore, the pressure in the pressure side back pressure chamber 61 can be arbitrarily set by adjusting the set pressure of the pressure control valve 70 by the energization current to the solenoid 71.

  Thereby, the pressure side damping valve 34 is bent and opened to a position where the pressure of the piston side chamber 12B in the pressure side flow path 32 and the elastic force of the pressure side damping valve 34 and the pressure of the pressure side back pressure chamber 61 are balanced. Damping force is determined. Therefore, a desired compression-side damping force is generated according to the energization current to the solenoid 71 regardless of the piston speed.

According to the present embodiment, the following operational effects can be obtained.
(a) The expansion-side back pressure chamber 51 and the compression-side back pressure chamber 61 are provided on the back side of the expansion side damping valve 33 with respect to the expansion side flow channel 31 and the back side of the compression side attenuation valve 34 with respect to the pressure side flow channel 32, respectively. The piston side 13 includes an extension side back pressure introduction path 52 that guides the pressure of the rod side chamber 12A to the extension side back pressure chamber 51 and a pressure side back pressure introduction path 62 that guides the pressure of the piston side chamber 12B to the compression side back pressure chamber 61. Provided, when the respective pressures in the expansion-side back pressure chamber 51 and the compression-side back pressure chamber 61 reach arbitrary set pressures, the respective pressures in the expansion-side back pressure chamber 51 and the compression-side back pressure chamber 61 are changed to the piston-side chamber 12B. Each of the rod side chambers 12 </ b> A has a pressure control valve 70 that relieves each of the rod side chambers 12 </ b> A and controls the pressure in each of the extension side back pressure chamber 51 and the compression side back pressure chamber 61, and can adjust each of the extension side damping force and the compression side damping force. did. By adjusting the set pressure of the pressure control valve 70 with a simple structure using the pressure control valve 70, the extension / pressure damping force can be directly controlled regardless of the piston speed. The number of processing steps and assembly steps for the component parts are not increased, and it is simplified.

  (b) The extension-side back pressure relief path 80A and the compression-side back pressure relief path 80B for relieving the respective pressures in the extension-side back pressure chamber 51 and the compression-side back pressure chamber 61 are respectively connected to the extension-side back pressure introduction path 52 and the compression side. By communicating with each of the back pressure introduction paths 62, the relief paths 80 </ b> A and 80 </ b> B can be easily formed in the piston rod 13.

  (c) Since the extension side back pressure relief path 80A and the pressure side back pressure relief path 80B are shared as the common relief path 80, the relief paths 80A and 80B can be easily formed in the piston rod 13.

  (d) The common relief path 80 has a stepped hole shape including a small diameter path 81 connected to the expansion side back pressure introduction path 52 and a large diameter path 82 connected to the compression side back pressure introduction path 62, and the pressure control valve 70 has a small diameter on the tip side. A stepped shaft comprising a portion 72A and a proximal-side large-diameter portion 72B is formed, and the distal end surface of the small-diameter portion 72A can be brought into and out of contact with the small-diameter passage 81 of the common relief passage 80 and the step-shaped valve seat 83 of the large-diameter passage 82. The step surfaces of the diameter portion 72B and the small diameter portion 72A are made to face the large diameter path 82 of the common relief path 80. The pressure relief characteristic of the extension-side back pressure chamber 51 can be set by the pressure receiving area where the tip surface of the small diameter portion 72A of the pressure control valve 70 faces the small diameter path 81 of the common relief path 80. The pressure relief characteristic of the pressure-side back pressure chamber 61 can be set by the pressure receiving area where the step surface of the large diameter portion 72B and the small diameter portion 72A of the pressure control valve 70 faces the large diameter path 82 of the common relief path 80. The relationship between the expansion side damping force and the compression side damping force is determined by the correlation between the pressure receiving area of the tip surface of the small diameter portion 72A of the pressure control valve 70 and the pressure receiving areas of the step surfaces of the large diameter portion 72B and the small diameter portion 72A of the pressure control valve 70. Can be adjusted.

  (e) The extension-side back pressure chamber 51 and the compression-side back pressure chamber 61 are provided on the outer periphery of the valve stoppers 25 and 23 for the extension-side damping valve 33 and the compression-side damping valve 34, respectively. The backup collars 53 and 63 are urged by the springs 54 and 64 to the extension side damping valve 33 and the compression side damping valve 34, respectively. The pressure receiving area that faces the expansion side back pressure chamber 51 is made larger than the pressure receiving area that faces the expansion side back pressure chamber 51, and the pressure side damping valve 34 makes the pressure receiving area that faces the pressure side flow path 32 larger than the pressure receiving area that faces the pressure side back pressure chamber 61. Accordingly, when the relief pressure is set high, when the pressure in the extension side flow path 31 and the extension side back pressure chamber 51 rises during the extension side stroke, the extension side is caused by the difference in the pressure receiving area of the extension side damping valve 33 described above. The backup collar 53 on the side of the back pressure chamber 51 is pushed down, and the extension side damping valve 33 backed up by the backup collar 53 is opened, so that the upper limit (maximum damping force) of the extension side damping force can be set. Further, when both the pressure in the pressure side flow path 32 and the pressure side back pressure chamber 61 rise in the pressure side stroke, the backup collar 63 on the pressure side back pressure chamber 61 side is pushed down due to the difference in the pressure receiving area of the pressure side damping valve 34 described above. The pressure side damping valve 34 backed up by the backup collar 63 is opened, and the upper limit (maximum damping force) of the pressure side damping force can be set.

  (f) Since the pressure control valve 70 is a proportional solenoid pressure control valve 70, the set pressure of the pressure control valve 70 can be adjusted by changing the energization current to the proportional solenoid, and the energization current to the proportional solenoid. Accordingly, a predetermined damping force can be generated regardless of the piston speed.

  Although the embodiments of the present invention have been described in detail with reference to the drawings, the specific configuration of the present invention is not limited to these embodiments, and even if there is a design change or the like without departing from the gist of the present invention. It is included in the present invention.

FIG. 1 is a cross-sectional view showing a damping force adjusting hydraulic shock absorber. FIG. 2 is a cross-sectional view showing the damping force adjusting structure of FIG. FIG. 3 shows the extension side stroke of the damping force adjusting hydraulic shock absorber, (A) is a sectional view showing a non-relief state of the extension side back pressure, and (B) is a sectional view showing a relief state of the extension side back pressure. is there. 4A and 4B show a pressure side stroke of the damping force adjusting hydraulic shock absorber, FIG. 4A is a cross-sectional view showing a non-relief state of the pressure side back pressure, and FIG. 4B is a cross-sectional view showing a relief state of the pressure side back pressure. 5A and 5B show the operation of the pressure control valve. FIG. 5A is a cross-sectional view showing an extended-side back pressure relief state, and FIG. 5B is a cross-sectional view showing a pressure-side back pressure relief state.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Hydraulic shock absorber 12 Cylinder 12A Rod side chamber 12B Piston side chamber 13 Piston rods 23 and 25 Valve stopper 24 Piston 31 Stretch side flow path 32 Pressure side flow path 33 Stretch side damping valve 34 Pressure side damping valve 50 Damping force adjustment device 51 Stretch side back pressure Chamber 52 Extension side back pressure introduction path 53 Backup collar 54 Leaf spring (spring)
61 pressure side back pressure chamber 62 pressure side back pressure introduction path 63 backup collar 64 leaf spring (spring)
70 Pressure control valve 71 Solenoid 72 Valve body 72A Small diameter portion 72B Large diameter portion 80 Common relief path 80A Extended side back pressure relief path 80B Pressure side back pressure relief path 81 Small diameter path 82 Large diameter path 83 Stepped valve seat

Claims (5)

A piston rod is inserted into the cylinder, and the inside of the cylinder is partitioned into a rod side chamber and a piston side chamber by a piston fixed to the piston rod, and the rod side chamber and the piston side chamber open and close the extension side channel provided in the piston and the extension side channel. In the damping force adjustment type hydraulic shock absorber connected to each other via the expansion side damping valve, the pressure side flow path, and the pressure side damping valve that opens and closes the pressure side flow path,
On the back side of the expansion side damping valve on the expansion side flow path and on the back side of the compression side attenuation valve on the pressure side flow path, respectively, an extension side back pressure chamber and a pressure side back pressure chamber are provided.
Each of the piston rods is provided with an extension side back pressure introduction path for guiding the pressure of the rod side chamber to the extension side back pressure chamber and a pressure side back pressure introduction path for guiding the pressure of the piston side chamber to the compression side back pressure chamber.
When the respective pressures in the expansion-side back pressure chamber and the compression-side back pressure chamber reach an arbitrary set pressure, the pressures in the expansion-side back pressure chamber and the compression-side back pressure chamber are relieved in the piston-side chamber and the rod-side chamber, respectively. A damping force adjustment type hydraulic pressure having a pressure control valve for controlling the respective pressures of the extension side back pressure chamber and the pressure side back pressure chamber, and enabling adjustment of each of the extension side damping force and the compression side damping force Shock absorber. The piston rod is provided with an extension side back pressure relief path through which the extension side back pressure introduction path communicates and a pressure side back pressure relief path through which the compression side back pressure introduction path communicates,
The damping force adjusting type hydraulic shock absorber according to claim 1, wherein the pressure control valve opens the extension side back pressure relief path and the pressure side back pressure relief path with respect to each of the piston side chamber and the rod side chamber. The extension side back pressure relief path and the pressure side back pressure relief path are common relief paths,
The common relief path has a stepped hole shape consisting of a small diameter path connected to the extension side back pressure introduction path and a large diameter path connected to the compression side back pressure introduction path.
The pressure control valve has a stepped shaft shape consisting of a small diameter portion on the distal end side and a large diameter portion on the proximal end side, and the distal end surface of the small diameter portion can be brought into contact with and separated from the stepped valve seat of the small diameter passage and the large diameter passage of the common relief passage. The damping force adjusting hydraulic shock absorber according to claim 2, wherein the step surface of the large diameter portion and the small diameter portion faces the large diameter path of the common relief path. Each of the extension-side back pressure chamber and the compression-side back pressure chamber is formed by a valve stopper for each of the extension-side damping valve and the compression-side damping valve, and a backup collar provided on the outer periphery of the valve stopper, and each backup collar is a spring. Is applied to each of the expansion side damping valve and the compression side damping valve,
The expansion side damping valve makes the pressure receiving area facing the expansion side flow path larger than the pressure receiving area facing the expansion side back pressure chamber,
4. The damping force adjusting type hydraulic shock absorber according to claim 1, wherein the pressure side damping valve has a pressure receiving area facing the pressure side flow path larger than a pressure receiving area facing the pressure side back pressure chamber.   The damping force adjusting hydraulic shock absorber according to any one of claims 1 to 4, wherein the pressure control valve is a proportional solenoid pressure control valve.

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