JP2019108941A - Buffer - Google Patents

Abstract

To provide a low-vibration and low-noise hydraulic buffer according to the present invention.SOLUTION: A buffer comprises: a piston 3 which partitions the inside of a cylinder into a first chamber and a second chamber; a first passage 15 and a first main valve 20 which let working fluid in the first chamber flow to the second chamber; a second passage 16 and a second main valve 36 which let working fluid in the second chamber flow to the first chamber; a first back pressure chamber 23 which adjusts valve opening pressure of the first main valve; a second back pressure chamber 38 which adjusts valve opening pressure of the second main valve; common passages 29, 30, 44, 48, and 49 which link the first back pressure chamber and the second back pressure chamber to each other; and a pilot valve which controls flows of working fluids in the common passages. The pilot valve comprises: a first pilot valve body 81; a second valve body 82 provided with a first valve seat 82A where the first valve body is seated; a second valve seat 58C where the second valve body is seated; and a valve spring 59 which energizes the second valve body toward the first valve body or second valve seat.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a shock absorber that controls the flow of working fluid relative to the stroke of a piston rod to generate a damping force.

  In JP 2005-351419 A (patent document 1), there are provided a piston rod movably inserted in a cylinder via a piston, and first and second oil chambers partitioned in the cylinder via a piston, An expansion port and a pressure port formed on the piston and communicating the first and second oil chambers, and an expansion leaf valve and a pressure leaf valve provided openably and closably at the outlet end of the expansion port and the pressure port, respectively. Hydraulic shock absorbers are described. The hydraulic shock absorber further includes a pilot passage provided in the piston and the piston rod to bypass the expansion leaf valve and the pressure leaf valve, and a back side of the expansion leaf valve and the pressure leaf valve branched from the pilot passage. And a poppet-type valve body provided in the middle of the pilot passage to open and close the pilot passage, and provided at the back of the valve body. And a spring for biasing the valve in a closing direction, and a solenoid provided opposite to the spring. The poppet-type valve body is a hollow first valve body having a seat hole and a lateral hole communicating with the pilot passage, and is movably inserted into the first valve body to open and close the seat hole and the lateral hole. It consists of the 2nd valve body. A spring is abutted against the back of the second valve body, and the first and second valve bodies are biased in the closing direction by the spring. Further, a back pressure chamber is provided on the back side of the valve body, and this back pressure chamber is in communication with the above-mentioned seat hole through a communication hole formed in the second valve body. The hydraulic shock absorber of Patent Document 1 can adjust the damping force while adjusting the cracking pressure of the valve according to the current applied to the solenoid (see paragraph 0014).

Patent document 1: JP-A-2005-351419

  In the hydraulic shock absorber of Patent Document 1, the first valve body has no force other than the force by the fluid, and in particular, when switching from the extension stroke to the compression stroke, the pressure and the flow rate fluctuate. It is conceivable that the action becomes vibrational by switching and the force acts in an oscillating manner, which causes the generation of sound.

  Therefore, in view of the above-mentioned problems, an object of the present invention is to provide a low vibration and low noise hydraulic shock absorber.

In order to achieve the above object, the shock absorber of the present invention is
A cylinder in which the working fluid is sealed;
A piston slidably fitted inside the cylinder to divide the inside of the cylinder into a first chamber and a second chamber;
A piston rod having one end connected to the piston and the other end extending outward from the cylinder;
A first passage provided in the piston and flowing the working fluid of the first chamber to the second chamber in a stroke in which the volume of the first chamber decreases;
A second passage provided in the piston and flowing the working fluid of the second chamber to the first chamber in a stroke in which the volume of the second chamber decreases;
A first main valve for opening and closing the first passage;
A first back pressure chamber for adjusting an opening pressure of the first main valve;
A second main valve for opening and closing the second passage;
A second back pressure chamber for adjusting the valve opening pressure of the second main valve;
A common passage communicating the first back pressure chamber and the second back pressure chamber;
A pilot valve disposed inside the common passage to control the flow of the working fluid in the common passage;
An actuator controlling movement of the pilot valve;
Equipped with
The pilot valve is
A first valve body movably provided inside the common passage;
A second valve body provided with a first valve seat on which the first valve body is seated and movably provided inside the common passage;
A second valve seat on which the second valve body is seated;
A valve spring biasing the second valve body toward the first valve body or the second valve seat;
Have
The first valve body is biased toward the first valve seat by the actuator.

  According to the present invention, a low vibration and low noise hydraulic shock absorber can be provided.

FIG. 2 is a cross-sectional view of the main part of the shock absorber 1 of the first embodiment. It is sectional drawing which expands and shows a part of FIG. FIG. 10 is an explanatory diagram of the operation of the shock absorber according to the first embodiment, in which the extension side pilot valve body is slightly opened and the compression side pilot valve body is in a closed state. It is a figure which shows a flow. It is sectional drawing which expands and shows the vicinity of the piston bolt 5 of FIG. FIG. 10 is an explanatory view of the operation of the shock absorber 1 of the first embodiment, and is a cross-sectional view showing the pilot flow of the working fluid at the time of the extension stroke of the piston rod 9; FIG. 10 is an explanatory view of the operation of the shock absorber 1 of the first embodiment, and is a cross-sectional view showing the pilot flow of the working fluid during the compression stroke of the piston rod 9; FIG. 10 is an explanatory view of the operation of the shock absorber 1 of the first embodiment, and is a cross-sectional view showing the pilot flow of the working fluid at the time of failure at the extension stroke of the piston rod 9; FIG. 10 is an explanatory view of the operation of the shock absorber 1 according to the first embodiment, and is a cross-sectional view showing a pilot flow of the working fluid at the time of failure during the compression stroke of the piston rod 9; FIG. 7 is an enlarged view of a part of a main part of the shock absorber 1 of the second embodiment. FIG. 10 is a drawing showing a part of the main part of the shock absorber 1 of the second embodiment in an enlarged manner, and a cross-sectional view showing the pilot flow of the working fluid during the extension stroke of the piston rod 9; FIG. 13 is an enlarged view of a part of the main part of the shock absorber according to the second embodiment, and is a cross-sectional view showing the pilot flow of the working fluid during the extension stroke of the piston rod 9; It is a figure which expands and shows a part of principal part of the buffer of Example 2, and is sectional drawing which shows another form of arrangement | positioning of a spring.

  Hereinafter, examples according to the present invention will be described.

Example 1
A first embodiment of the present invention will be described with reference to the attached drawings.

  FIG. 1 is a cross-sectional view of the main part of the shock absorber 1 of the first embodiment. In the following description, the upper direction (upper side) and the lower direction (lower side) in FIG. 1 are the upper direction (upper side) and the lower direction (lower side) of the shock absorber 1. Although the shock absorber 1 shown in the first embodiment is a single cylinder type damping force adjustment type hydraulic shock absorber, it can be applied to a double cylinder type damping force adjustment type hydraulic shock absorber including a reservoir.

  As shown in FIG. 1, a piston 3 is slidably fitted in the cylinder 2. The piston 3 divides the inside of the cylinder 2 into two chambers of a cylinder upper chamber (first chamber) 2A and a cylinder lower chamber (second chamber) 2B. The shaft portion 6 of the piston bolt 5 is inserted into the shaft hole 4 of the piston 3. The lower end portion of the substantially cylindrical case member 8 is connected to the substantially bottomed cylindrical head portion 7 of the piston bolt 5 by a screw connection portion 10. The screw connection portion 10 is constituted by an external thread formed on the outer peripheral surface of the lower end portion of the case member 8 and an internal thread formed on the inner peripheral surface of the head 7.

  The upper end of the piston bolt 5 is opened to the bottom surface 7 a of the head 7, and an axial hole 50 extending to the distal end side (lower end side) along the axial center of the piston bolt 5 is formed. As shown in FIG. 2, the axial hole 50 has an axial passage 48 formed in the upper part thereof to form an axially extending passage, and a diameter smaller than the axial passage 48 at the lower end side of the axial passage 48. And an axial passage 49 forming a large passage. The lower end of the shaft hole 50 is opened at the tip (lower end) of the piston bolt 5 and a lower end opening 61 having a diameter larger than that of the axial passage 49 is formed.

  In the lower end opening 61, a cylindrical sheet member 58 having an outer diameter substantially the same as that of the lower end opening 61 and having a bottom, and whose upper end contacts a step 61a provided on the upper end side of the lower end opening 61 Inserted into In addition, a concave spring receiving portion 58A is provided on the bottom portion 58a of the sheet member 58. Furthermore, a closing plug 35 for fixing the seat member 58 is provided at the lower end opening 61 on the lower surface side of the seat member 58, and is fixed to the piston bolt 5 by screwing or the like. An axial passage 30 is formed on the inner diameter side of the seat member 58.

  As shown in FIG. 1, the lower end portion of the piston rod 9 is connected to the upper end portion of the case member 8 by a screw connection portion 11. The screw connection portion 11 is constituted by a female screw formed on the inner peripheral surface of the upper end portion of the case member 8 and a male screw formed on the outer peripheral surface of the lower end portion of the piston rod 9. A nut 12 is screwed into the lower end portion of the piston rod 9, and the nut 12 is brought into contact with the upper end of the case member 8 and tightened, whereby the loosening of the screw connection portion 11 is suppressed. A small diameter portion 13 is formed at the lower end of the piston rod 9, and an O-ring 14 for sealing between the case member 8 and the piston rod 9 is attached to an annular groove 13a formed on the outer peripheral surface of the small diameter portion 13. Ru.

  The piston 3 is provided with an extension side passage 15 whose one end (upper end) opens to the cylinder upper chamber 2A side and a compression side passage 16 whose one end (lower end) opens to the cylinder lower chamber 2B side. At the lower end of the piston 3, an extension damping valve 17 is provided which controls the flow of the working fluid in the extension passage 15. At the upper end of the piston 3, a compression side damping valve 18 is provided which controls the flow of the working fluid in the compression side passage 16.

  As shown in FIG. 2, the expansion side damping valve 17 is fixed to the piston bolt 5 by the expansion side main valve 20 seated on the annular seat portion 19 formed on the outer peripheral side of the lower end face of the piston 3 and the nut 21. And an extension side back pressure chamber 23 formed between the rear surface of the extension side main valve 20 and the valve member 22. The pressure in the expansion side back pressure chamber 23 acts on the expansion side main valve 20 in the valve closing direction. A washer 24, a spacer 25 and a disc valve 26 are provided between the nut 21 and the valve member 22 sequentially from the lower side. The inner peripheral edge of the disc valve 26 is sandwiched between the inner peripheral edge of the valve member 22 and the spacer 25. The extension-side main valve 20 is a packing valve in which an annular seal portion 20A made of an elastic body contacts the inner peripheral surface of the valve member 22 over the entire circumference.

  The extension side back pressure chamber 23 is in communication with the lower cylinder chamber 2B via the passage 27 formed in the valve member 22 and the disc valve 26. The extension side back pressure chamber 23 is always in communication with the cylinder lower chamber 2B via an orifice 26A formed in the disk valve 26. The disc valve 26 opens when the pressure in the extension side back pressure chamber 23 reaches a predetermined pressure, and relieves the pressure in the extension side back pressure chamber 23 to the cylinder lower chamber 2B. Further, the extension-side back pressure chamber 23 is a radial passage (first radial passage) 29 formed in the piston bolt 5 via an extension-side back pressure introducing valve (first back pressure introducing valve) 28 consisting of a disk valve. It is communicated with. The radial passage 29 communicates with an axial passage 30 (common passage) formed in the piston bolt 5.

  The extension side back pressure introduction valve 28 is a check valve that allows only the flow of the working fluid from the radial passage 29 to the extension side back pressure chamber 23. The extension side back pressure introducing valve 28 is seated on an annular seat portion 31 formed on the inner peripheral side of the passage 27 on the upper surface of the valve member 22. The inner peripheral edge portion of the extension-side back pressure introducing valve 28 is sandwiched between the inner peripheral edge portion of the valve member 22 and the spacer 32. The extension side back pressure chamber 23 communicates with the radial passage 29 through the orifice 28A formed in the extension side back pressure introduction valve 28 when the extension side back pressure introduction valve 28 is opened.

  The axial passage 30 is in communication with a radial passage 33 (a compression side discharge passage) formed in the piston bolt 5. The radial passage 33 is in communication with the extension passage 15 via a compression check valve 34 provided in the piston 3. The radial passage 33 is always in communication with the extension passage 15 through the orifice 34 A formed in the compression check valve 34. The compression check valve 34 only allows the flow of working fluid from the radial passage 33 to the extension passage 15.

  The compression-side damping valve 18 is fixed between the head 7 of the piston bolt 5 and the piston 3 and a compression-side main valve 36 seated on an annular seat portion 66 formed on the outer peripheral side of the upper end surface of the piston 3 And a compression side back pressure chamber 38 formed between the back surface of the compression side main valve 36 and the valve member 37. The pressure in the compression side back pressure chamber 38 acts on the compression side main valve 36 in the valve closing direction. Between the head 7 of the piston bolt 5 and the valve member 37, a washer 39, a spacer 40 and a disc valve 41 are provided in order from the upper side. The inner peripheral edge of the disc valve 41 is sandwiched between the inner peripheral edge of the valve member 37 and the spacer 40. The contraction side main valve 36 is a packing valve in which an annular seal portion 36A made of an elastic body is in contact with the inner peripheral surface of the valve member 37 over the entire circumference.

  The compression side back pressure chamber 38 is in communication with the cylinder upper chamber 2A via the passage 42 formed in the valve member 37 and the disc valve 41. The compression side back pressure chamber 38 is always in communication with the cylinder upper chamber 2A via the orifice 41A formed in the disc valve 41. The disc valve 41 opens when the pressure in the compression side back pressure chamber 38 reaches a predetermined pressure, and relieves the pressure in the compression side back pressure chamber 38 to the cylinder upper chamber 2A. Further, the compression side back pressure chamber 38 is in communication with a radial direction passage (second radial direction passage) 44 formed in the piston bolt 5 through a compression side back pressure introduction valve 43 formed of a disk valve. The radial passage 44 is in communication with the axial passage 48 (common passage) of the piston bolt 5.

  In the present embodiment, the axial hole 50 of the piston bolt 5 constitutes an axial passage. The axial passage 30, the axial passage 49 and the axial passage 48 each constitute a part of the axial passage by the axial hole 50. Axial passage 30, axial passage 49 and axial passage 48 may be referred to as first axial passage, second axial passage and third axial passage, respectively. The axial passage 30 and the axial passage 49 constitute a large diameter axial passage portion whose diameter is larger than that of the axial passage 48. The axial passage 48 constitutes a small diameter axial passage portion having a smaller diameter than the axial passage 30 and the axial passage 49.

  Further, an axial passage formed by the axial hole 50 constitutes a common passage communicating the extension side back pressure chamber (first back pressure chamber) 23 with the compression side back pressure chamber (second back pressure chamber) 38. Since the radial passage 29 is provided between the axial passage by the axial hole 50 and the extension side back pressure chamber 23, the radial passage 29 constitutes a part of the common passage. Further, since the radial passage 44 is provided between the axial passage by the axial hole 50 and the compression side back pressure chamber 38, the radial passage 44 constitutes a part of the common passage. That is, the common passage includes the radial passage 29 and the radial passage 44 in the axial passages 10, 48, 49 by the axial holes 50. The piston bolt 5 is a passage forming member in which a common passage is formed.

  The compression side back pressure introduction valve (second back pressure introduction valve) 43 is a check valve that allows only the flow of working fluid from the radial passage 44 to the compression side back pressure chamber 38. The compression side back pressure introducing valve 43 is seated on an annular seat portion 45 formed on the inner peripheral side of the passage 42 in the lower surface of the valve member 37. An inner peripheral edge portion of the compression side back pressure introducing valve 43 is sandwiched between the inner peripheral edge portion of the valve member 37 and the spacer 60. The compression side back pressure chamber 38 is communicated with the radial passage 44 through an orifice 43A formed in the compression side back pressure introduction valve 43 when the compression side back pressure introduction valve 43 is opened.

  The axial passage 48 is in communication with a radial passage 46 (extending side discharge passage) formed in the piston bolt 5. The radial passage 46 is in communication with the compression passage 16 via an extension check valve 47 provided in the piston 3. The radial passage 46 is always in communication with the compression passage 16 via an orifice 47 A formed in the expansion check valve 47. The extension check valve 47 only allows the flow of working fluid from the radial passage 46 to the compression passage 16.

  As shown in FIG. 4, a compression side pilot valve body (first valve body) 81 and an expansion side pilot valve body (second valve body) 82 are disposed in the axial hole 50 of the piston bolt 5. Together with the pilot valve. The compression side pilot valve body 81 is located in the axial passage 48 and connected via the tapered portion 81B with a base portion 81A which is slidably fitted to a portion above the radial passage 44 of the axial passage 48 And a small diameter portion 81C to be formed. A seating surface 81D formed in a tapered shape is formed on the outer peripheral edge of the lower end of the small diameter portion 81C, and the seating surface 81D is a seat portion (first valve seat) 82A provided on the extension side pilot valve body 82 described later. Sit down. The base portion 81A is an upper end portion of the compression side pilot valve body 81, and a seating surface 81D is formed at a lower end portion of the compression side pilot valve body 81.

  In addition, the fitting portion is such that the diameter once increases halfway through the lower end of the small diameter portion 81C, and the fitting portion is fitted to the axial passage 48 when the compression side pilot valve body 81 moves in the valve opening direction (up direction). A (expanded diameter portion) 81F is provided. The fitting portion 81F is provided with a notch 65A. The notch 65A forms an orifice communicating between the upstream side and the downstream side when the fitting portion 81F is fitted to the axial passage 48. Further, the compression side pilot valve body 81 is provided with a communication hole 81E communicating the lower end side and the upper end side, and the axial direction passage 30 is communicated with the pilot valve body back pressure chamber 48A of the compression side pilot valve body 81. . For this purpose, a notch 72B is provided at the lower end portion of the operation pin 72 that abuts on the upper end surface 81L of the compression side pilot valve body 81.

  An extension side pilot valve body 82 is disposed on the lower end side of the compression side pilot valve body 81 in the axial passage 48. The extension side pilot valve body 82 is formed in a circular tubular shape, and a seat portion 82A is formed in an annular shape at the upper end side opening edge of the inner diameter portion. The extension-side pilot valve body 82 has a short length in the central axis direction along the moving direction, and an annular shape is more appropriate. Further, on the lower end side of the inner diameter portion, an annular spring receiving portion 82B having a shape in which the diameter is expanded stepwise is formed. Further, a seating surface 82C formed in a tapered shape is formed at the outer peripheral edge of the circular pipe, and the seat surface (second valve seat) 58C of the seat member 58 provided in the axial passage 30 is seated. Further, the expansion side pilot valve body 82 is biased in the upward direction (valve opening direction) by a valve spring 59 interposed between the spring receiving portion 82B and the concave spring receiving portion 58A.

  One end portion of the valve spring 59 is in contact with the piston bolt 5, and the other end portion is in contact with the extension pilot valve body 82. The seat portion (first valve seat) 82A is formed on the upper end surface side of the expansion side pilot valve body 82 in the central axis direction and the compression side pilot valve body 81 side, and the valve spring 59 is below the expansion side pilot valve body 82. It is in contact with the end face side. The biasing force of the valve spring 59 causes the expansion side pilot valve body 82 to abut on the compression side pilot valve body 81.

  As described above, the pilot valve of the present embodiment includes the compression side pilot valve body (first valve body) 81, the extension side pilot valve body (second valve body) 82, and the seat portion 58C (that is, the seat member 58). And a valve spring 59. The piston bolt 5 constitutes a passage forming member in which the common passage is formed, and constitutes a pilot valve accommodating member for accommodating the pilot valve.

  The valve spring 59 is arranged in an axial passage 30 in which the radial passage 29 and the radial passage 33 are provided, ie the radial passage 29 and the radial passage 33 are provided radially outward of the valve spring 59. Therefore, the valve spring 59, the radial passage 29 and the radial passage 33 can be disposed in a small space, and the shock absorber can be miniaturized.

  An opening formed between the seating surface 81D of the compression-side pilot valve body 81 and the seat portion 82A or a space between the seating surface 82C of the extension-side pilot valve body 82 and the seat portion 58C with such a configuration When the axial passage 30 and the axial passage 49 communicate with each other and flow occurs by the opening, a pressure difference is generated, and the axial passage 30 is connected to the extension side back pressure chamber 23 at the boundary of the opening. The side pilot chamber 63 is formed, and the axial passage 49 side forms a compression side pilot chamber 62 connected to the compression side back pressure chamber 38.

  As shown in FIG. 1, the solenoid 71 has a case member 8, a coil 74, and an operating pin 72, and a plunger 85 is coupled to the outer peripheral surface of the operating pin 72. The plunger 85, which is also called a movable core, is formed in a substantially cylindrical shape by a magnetic body. In the plunger 85, a thrust due to the magnetic force generated by energizing the coil 74 is generated downward. Therefore, a normally open type valve is constructed in which the spring force by the valve spring 59 is in the valve opening direction and the solenoid thrust is in the valve closing direction. In the present embodiment, the solenoid 71 constitutes an actuator that controls the movement of the pilot valve.

  The operating pin 72 is supported so as to be movable in the vertical direction (axial direction) by a bush 90 incorporated in the stator core 76 and a bush 91 incorporated in the core 84. The moving direction of the actuating pin 72 corresponds to the on / off valve direction of the compression side pilot valve body 81 and the extension side pilot valve body 82.

  The core 84 has an inner peripheral surface 71A and a lower end surface 71B, and the diameter (inner diameter) of the inner peripheral surface 71A is smaller than the diameter (outer diameter) of the base 81A of the compression side pilot valve body 81. When the base 81A of the compression side pilot valve body 81 abuts on the lower end surface 71B of the solenoid 71, the upward movement of the piston bolt 5 with respect to the axial hole 50 is restricted. The operating pin 72 has a pilot valve back pressure chamber 48A on the compression side pilot valve body 81 side and a communication hole 72A for communicating between the operating pin back pressure chamber 73 of the operating pin 72 on the opposite side. Provided.

  Next, the operation of this embodiment will be described. The operation of the shock absorber 1 includes an extension stroke and a compression stroke. In the extension stroke, the piston 3 moves upward, and in the compression stroke, the piston 3 moves downward.

  First, the operation at the time of the extension stroke when the coil 74 is energized will be described.

  During the extension stroke shown in FIGS. 2 and 5, the pressure in the piston upper chamber 2A rises with the upward movement of the piston 3, and the extension side passage 15, the orifice 34A, and the radial passage 33 from the piston upper chamber 2A. Flow to the expansion side pilot chamber 63 (dotted arrow). The pressure in the expansion side pilot chamber 63 is increased by this flow, and a force in the valve opening direction (upward direction) acts on the expansion side pilot valve body 82. Further, in the compression side pilot valve body 81, the force in the valve opening direction by the pressure in the expansion side pilot chamber 63 acting on the pressure receiving area inside the seating surface 81D, and the expansion side pilot in the pilot valve back pressure chamber 48A. The force in the valve closing direction by the pressure in the chamber 63 acts, but since the pressure receiving area by the pilot valve back pressure chamber 48A is larger than the pressure receiving area inside the seating surface 81D, the force in the valve closing direction Keep sitting large. Therefore, the expansion side pilot valve body 82 and the compression side pilot valve body 81 operate integrally.

  A force in the valve opening direction acts on the pressure receiving area inside the seating surface 82C of the extension side pilot valve body 82 on the integrated pilot valve body 81, 82, and the pilot valve with almost the same pressure via the communication hole 81E. Since a force in the valve closing direction acts on the pressure receiving area of the body back pressure chamber 48A, the force in the valve opening direction is generated by the pressure difference between the pressure receiving area inside the seating surface 82C and the pressure receiving area of the pilot valve back pressure chamber 48A. Works. Further, a force generated by the solenoid 71 acts on the actuating pin 72 in the valve closing direction. Therefore, the opening of the valve is controlled mainly by the balance between the force in the valve opening direction by the pressure, the force in the valve closing direction of the solenoid 71, and the force in the valve opening direction by the valve spring 59.

  With the opening of the valve body, a flow to the piston lower chamber 2B occurs through the extension side pilot chamber 63, the compression side pilot chamber 62, the check valve 47, and the compression side passage 16.

  Based on this, the pressure in the piston upper chamber 2A rises during the extension stroke, and a damping force is generated. Further, the pressure of the expansion side pilot chamber 63 can be a pressure corresponding to the force generated by the solenoid 71.

  At the same time, a flow to the piston lower chamber 2B is also generated in the extension damping valve 17 through the extension passage 15 and the valve opening of the extension main valve 20 (solid arrow).

  At this time, the extension side pilot chamber 63 is connected to the extension side back pressure chamber 23 through the check valve 31, and the pressure of the extension side pilot chamber 63 is controlled, so the valve opening pressure of the extension side main valve 20 Will be controlled.

  Therefore, when the expansion side main valve 20 is closed (when the piston speed is in the low speed range), a damping force is generated according to the opening degree of the expansion side pilot valve body 82, and when the expansion side main valve 20 is opened. At the time when the piston speed is in the high speed region, a flow occurs in both the expansion side main valve 20 and the expansion side pilot valve body 82, and a damping force is generated according to the opening degree of both. At this time, the control pressure of the expansion side pilot chamber 63 can be adjusted by the current supplied to the coil 40, and as a result, the pressure of the expansion side back pressure chamber 23 can be adjusted. Can be adjusted.

  Next, the operation in the contraction step will be described.

  During the compression stroke shown in FIGS. 3 and 6, the pressure in the piston lower chamber 2B increases with the downward movement of the piston 3, and from the piston lower chamber 2B the contraction side passage 16, the orifice 47A, and the radial passage 46 Flow to the compression side pilot chamber 62 (dotted arrow). The pressure in the compression side pilot chamber 62 is increased by this flow. At this time, the compression side pilot chamber 62 is connected to the compression side back pressure chamber 38 through the check valve 43, and the pressure in the compression side back pressure chamber 38 is increased to close the compression side main valve 36. Power acts on the

  The pressure in the valve opening direction acts on the pressure receiving area of the compression side pilot chamber 81 due to the difference in diameter between the base 81A of the compression side pilot valve 81 and the seating surface 81D. On the expansion side pilot valve body 82, a force in the direction to close the valve acts on the pressure receiving area due to the difference in diameter between the seating surface 81D and the seating surface 82C by the pressure of the compression side pilot chamber 62. At the same time, a force in the valve opening direction by the valve spring 59 acts on the extension side pilot valve body 82. When the force in the valve opening direction by the valve spring 59 among forces acting on the expansion side pilot valve body 82 is larger than the force in the valve closing direction by the pressure of the compression side pilot chamber 62 (the piston speed is in the low speed range When the expansion side pilot valve body 82 receives a force in the valve opening direction, a force in the direction of the expansion side pilot valve body 82 acts on the compression side pilot valve body 81, The pilot valve body 81 and the extension side pilot valve body 82 operate integrally, and the opening amount is controlled at the seating surface 82C.

  On the other hand, when the flow rate increases and the pressure in the compression side pilot chamber 62 increases, the force in the valve opening direction by the valve spring 59 among the forces acting on the expansion side pilot valve body 82 is closed by the pressure in the compression side pilot chamber 62 It becomes smaller than the force in the valve direction. In this case, regardless of the force acting on the compression side pilot valve body 81, since the force acts on the expansion side pilot valve body 82 in the valve closing direction, the flow path of the seating surface 82C is closed.

  On the other hand, when the solenoid 71 is energized, the compression side pilot valve body 81 receives the force in the valve closing direction by receiving the force generated on the actuating pin 72. At this time, in the pilot valve body 81, the opening amount of the seating surface 81D is controlled so that the force in the valve opening direction mainly due to the pressure of the compression side pilot chamber 62 and the force in the valve closing direction by the solenoid 71 are balanced. The pressure in the compression side pilot chamber 62 is controlled.

  At the same time, a flow to the piston upper chamber 2A is also generated in the compression side main valve 36 via the valve openings of the compression side passage 16 and the compression side main valve 36 (solid arrow).

  At this time, the compression side pilot chamber 62 is connected to the compression side back pressure chamber 38 through the check valve 43, and the pressure of the compression side pilot chamber 62 is controlled to open the valve pressure of the compression side main valve 36. Will be controlled.

  Therefore, when the compression side main valve 36 is closed (when the piston speed is in the low speed region), a damping force is generated according to the opening degree of the compression side pilot valve body 81, and the compression side main valve 36 is opened. At the time when the piston speed is in the high speed region, a flow occurs in both the compression side main valve 36 and the compression side pilot valve body 81, so that a damping force is generated in accordance with the degree of opening of both. At this time, the pressure of the compression side pilot chamber 62 can be adjusted by the current supplied to the coil 40, and as a result, the pressure of the compression side back pressure chamber 38 can be adjusted. It can be adjusted.

  Further, when switching from the extension stroke to the compression stroke, the expansion pilot valve body 82 is in contact with the seat portion 58C shown in FIG. 6 from the state in which the expansion pilot valve body 82 is in contact with the compression side pilot valve 81 shown in FIG. Moving. At this time, after the force in the valve closing direction by the pressure in the compression side pilot chamber 62 is overcome against the force in the valve opening direction by the valve spring 59 acting on the expansion side pilot valve body 82, the expansion side pilot valve body 82 Start the operation (valve closing operation). From this, in the switching stroke from the extension stroke to the compression stroke, the expansion pilot valve body 82 keeps a long state in contact with the compression pilot valve body 81, and after completely shifting to the compression stroke, the seat portion 58C Works to move to This enables stable operation of the expansion pilot valve body 82 in the switching stroke from the extension stroke to the contraction stroke.

  Next, with reference to FIG. 7 and FIG. 8, the operation at the time of failure such as disconnection of the coil 74 of the solenoid 71 or failure of the controller will be described.

  If the thrust of the plunger 85 is lost at the time of failure, the compression side pilot valve body 81 and the expansion side pilot valve body 82 are integrally moved upward by the biasing force of the valve spring 59 and the pressure by the expansion side pilot chamber 63. It is pushed up and strokes in the valve opening direction. The compression side pilot valve body 81 is positioned in the axial direction when the end surface 81 L abuts on the lower end surface 71 B of the solenoid 71. At the time of the failure, the fitting portion (expanded diameter portion) 81F of the compression side pilot valve body 81 is fitted in the axial passage 48 of the shaft hole 50 (common passage) of the piston bolt 5, and the axial passage 49 and the axial passage 48 and the hole are communicated through the orifice 65 by the notch 65A of the fitting portion 81F.

  Then, during the extension stroke at the time of failure, by adjusting the flow of the working fluid flowing from the axial passage 30 to the axial passage 48 through the orifice 65 with the flow passage area of the orifice 65 (shape of notch 65A) A pressure (pilot pressure) corresponding to the flow passage area of the orifice 65 can be generated in the pressure chamber 23. Thereby, it is possible to adjust the valve opening pressure of the expansion side main valve 20.

  Further, at the time of the compression stroke at the failure time, the compression side pilot valve body 81 is stroked in the valve opening direction by the force by the pressure of the compression side pilot chamber 62. The biasing force of the valve spring 59 acts on the expansion side pilot valve body 82 in the valve opening direction, and the force due to the pressure on the compression side pilot chamber 62 acts in the valve closing direction. It hold | maintains at the side pilot valve body 81 side. In any case, the compression side pilot valve body 81 is positioned in the axial direction when the end surface 81 L abuts on the lower end surface 71 B of the solenoid 71. At the time of the failure, the fitting portion 81F of the compression side pilot valve body 81 is fitted to the axial passage 48 of the shaft hole 50 (common passage) of the piston bolt 5 and the space between the axial passage 49 and the axial passage 48 is It is communicated via the orifice 65 by the notch 65A of the fitting portion 81F.

  By adjusting the flow of the working fluid flowing from the axial passage 48 to the axial passage 30 through the orifice 65 with the flow passage area of the orifice 65, the orifice 65 in the compression side back pressure chamber 38 (upstream back pressure chamber) The pressure corresponding to the flow passage area can be generated. Thereby, it is possible to adjust the valve opening pressure of the contraction side main valve 36.

  From the above, according to the present embodiment, the variable range of the damping force can be made large in both the extension stroke and the compression stroke. In addition, at the time of transition from the extension stroke to the compression stroke, or at the reverse transition thereof, the expansion pilot valve body 82 is less likely to vibrate, and a low noise shock absorber can be provided. Furthermore, it is possible to provide a shock absorber capable of generating a desired damping force characteristic even at the time of failure.

Example 2
A second embodiment of the present invention will be described with reference to FIGS. 9 to 12. The present embodiment is different from the first embodiment in the configuration of parts disposed in the shaft hole 50 of the piston bolt 5 and the configuration of the solenoid 71 for driving the same. The other configuration is the same as that of the first embodiment. Hereinafter, the same reference numerals as in the first embodiment are attached to the same configurations as the first embodiment, and particularly different configurations will be described.

  A compression side pilot valve body 81 and an expansion side pilot valve body 82 are disposed in the shaft hole 50 of the piston bolt 5, and together with the piston bolt 5 constitute a pilot valve. The compression side pilot valve body 81 has a cylindrical shape, and on the solenoid 71 side, has a solenoid side spring receiving portion 81J that is expanded radially outward of the cylinder. The compression side pilot valve body 81 has a seating surface 81D formed in a tapered shape at the outer peripheral edge of the lower end of the cylinder, and is seated on a seat portion 82A provided on the expansion side pilot valve body 82.

The compression side pilot valve body 81 has a large diameter portion 81A at the base (upper end) side and the lower portion of the solenoid side spring receiving portion 81J, and the small diameter portion 81C at the lower portion of the large diameter portion 81A. Have. On the way to the lower end of the small diameter portion 81C, a spring receiving portion 81G for receiving the upper end portion of the valve spring 81H is provided.
Further, the compression side pilot valve body 81 is provided with a communication hole 81E communicating the lower end side and the upper end side, and the communication hole 81E is an axial passage with the pilot valve body back pressure chamber 48A of the compression side pilot valve body 81. 30 and in communication.

  An extension side pilot valve body 82 is disposed on the lower end side of the compression side pilot valve body 81 in the axial passage 48. The extension side pilot valve body 82 is formed in a circular tubular shape, and a seat portion 82A is formed in an annular shape at the upper end side opening edge of the inner diameter portion. A spring receiving portion 82F for receiving the lower end portion of the valve spring 81H is formed at the opening edge portion on the outer peripheral side of the seat portion 82A. Further, a seating surface 82C formed in a tapered shape is formed on the outer peripheral edge on the lower end side of the extension side pilot valve body 82, and is seated on a seat portion 58C provided in the axial passage 30.

  A valve spring 81H is provided between the spring receiving portion 81G of the compression side pilot valve body 81 and the spring receiving portion 82F of the extension side pilot valve body 82, and the valve spring 81H extends to the seat portion 58C side of the expansion side pilot valve body 82. Energize in the direction of pressing it. Therefore, one end of the valve spring 81H is in contact with the compression side pilot valve body 81, and the other end is in contact with the extension side pilot valve body 82. Since the valve spring 81H is provided between the compression side pilot valve body 81 and the extension side pilot valve body 82, the valve spring 81H is hereinafter referred to as an inter-valve body spring 81H.

  The configuration of the solenoid 71 will be described.

  The solenoid 71 includes a case member 8, a coil 74, a plunger 85 in which a part of the compression side pilot valve body 81 is disposed, a stator core 76, and a core 84. The coil 74 is disposed inside the case member 8, and the core 84 is disposed so as to cover the lower surface side and the inner circumferential surface side of the coil 74.

  The core 84 has a collar portion 84A and a cylindrical portion 84B formed in a convex shape upward from the inner peripheral portion of the collar portion 84A. The core 84 is hollow on the radially inner side of the cylindrical portion 84B, and is disposed such that the lower surface of the collar portion 84A abuts on the head portion 7 of the piston bolt 5.

  A plunger 85, also referred to as a movable iron core, has a cylindrical portion 85C disposed with the central axis along the moving direction, and a projecting portion protruding radially inward (central axis side) from the inner peripheral lower end of the cylindrical portion 85C. And (bottom portion) 85B. The plunger 85 is an iron-based magnetic material, and is a bottomed cylindrical member having a hole (through hole) 85A in the bottom 85B. The plunger 85 is disposed in the hollow portion on the inner diameter side of the core 84. By energizing the coil 74, the plunger 85 generates a thrust due to the magnetic force in the upward direction. The plunger 85 is supported movably in the vertical direction (central axial direction, axial direction) with respect to the core 84.

  The bottom 85 B of the plunger 85 is disposed such that the upper surface thereof is in contact with the lower surface of a spring receiving portion 81 J provided on the compression side pilot valve body 81. A compression side spring 81K is disposed between the upper surface side of the spring receiving portion 81J and the spring receiving portion 76A of the stator core 76. The biasing force of the compression side spring 81K is set to be larger than the biasing force of the inter-valve body spring 81H. A force acts on the compression side pilot valve body 81 downward in the axial direction (valve closing direction) by the compression side spring 81 K, and contact with the bottom of the plunger 85 is maintained. Further, in a state where no current is applied to the solenoid 71, the compression side pilot valve body 81 is seated on the seat portion 82A and maintains the valve closed state. Further, the expansion side pilot valve body 82 receives the urging force of the axial direction downward (valve closing direction) by the compression side spring 81 K through the compression side pilot valve body 81, and is seated on the seat portion 58 C to maintain the valve closed state. . That is, the spring force constitutes a normally closed valve in which the solenoid force acts in the valve closing direction and the solenoid force acts in the valve opening direction.

  Next, the operation of this embodiment will be described.

  First, the operation in the extension stroke at the time of energization will be described using FIG.

  During the extension stroke, with the upward movement of the piston 3, the pressure in the piston upper chamber 2A rises, and from the piston upper chamber 2A through the extension side passage 15, the orifice 34A and the radial passage 33, the extension side pilot chamber A flow of up to 63 occurs (dotted arrow). The pressure in the expansion side pilot chamber 63 rises, and a force in the valve opening direction (upward direction) acts on the expansion side pilot valve body 82. In addition, in the compression side pilot valve body 81, a force in the valve opening direction due to the pressure of the expansion side pilot chamber 63 acting on the pressure receiving area inside the seating surface 81D, and the expansion side pilot in the pilot valve back pressure chamber 48A. The force in the valve closing direction by the pressure in the chamber 63 acts, but since the pressure receiving area by the pilot valve back pressure chamber 48A is larger than the pressure receiving area inside the seating surface 81D, the force in the valve closing direction Acts greatly. Furthermore, by setting the force in the valve closing direction by the compression side spring 81 K to be larger than the inter-valve body spring 81 H, the spring force also acts in the valve closing direction. Therefore, the compression side pilot valve body 81 holds the state of being seated on the seat portion 82A. Therefore, the expansion side pilot valve body 82 and the compression side pilot valve body 81 operate integrally.

  A force in the valve opening direction acts on the pressure receiving area inside the seating surface 82C of the extension side pilot valve body 82 on the integrated pilot valve body 81, 82, and the pilot valve with almost the same pressure via the communication hole 81E. The force in the valve closing direction acts on the pressure receiving area of the body back pressure chamber 48A, so the force in the valve opening direction is the pressure by the difference between the pressure receiving area inside the seating surface 82C and the pressure receiving area of the pilot valve back pressure chamber 48A. Works. Further, the plunger 85 receives the force in the valve opening direction generated by the solenoid 71, and applies a force in the valve opening direction to the compression side pilot valve body 81 via the bottom portion 85B. Therefore, the valve opening (pressure in the extension side pilot chamber 63) is controlled mainly by the balance between the force in the valve opening direction by pressure, the force in the valve opening direction of solenoid 71, and the force in the valve closing direction by spring. Be done.

  Similarly, the operation at the contraction step will be described with reference to FIG.

  During the compression stroke, with the downward movement of the piston 3, the pressure in the piston lower chamber 2B increases, and from the piston lower chamber 2B through the contraction side passage 16, the orifice 47A, and the radial passage 46, the compression side pilot chamber A flow to 62 occurs (dotted arrow). The pressure in the compression side pilot chamber 62 is increased by this flow. At this time, the compression side pilot chamber 62 is connected to the compression side back pressure chamber 38 through the check valve 43, and the pressure in the compression side back pressure chamber 38 is increased to close the compression side main valve 36. Power acts on the

  The compression side pilot valve body 81 is opened to the pressure receiving area by the difference between the diameter of the back pressure chamber 48A side of the compression side pilot valve body 81 and the diameter of the seat portion 82A by the pressure of the compression side pilot chamber 62. The force of direction acts. Furthermore, although the force by the compression side spring 81K and the inter-valve body spring 81H acts on the compression side pilot valve body 81, since the force of the compression side spring 81K is larger, the force acts in the valve closing direction.

  Further, a force in the valve closing direction acts on the expansion side pilot valve body 82 by the pressure of the compression side pilot chamber 62 on the pressure receiving area due to the difference in diameter between the seat portion 82A and the seating surface 82C. Furthermore, a force also acts on the expansion side pilot valve body 82 in the valve closing direction by the inter-valve body spring 81H. That is, the expansion side pilot valve body 82 always maintains the closed state. The compression side pilot valve body 81 receives a force in the valve opening direction through the bottom of the plunger 85 when the plunger 85 receives a force generated by the solenoid 71. Therefore, the valve opening (pressure in the compression side pilot chamber 62) is controlled mainly by the balance between the force in the valve opening direction by pressure, the force in the valve opening direction of solenoid 71, and the force in the valve closing direction by springs. Be done.

  Further, at the time of switching from the extension stroke to the compression stroke, the expansion side pilot valve body 82 moves, but as in the first embodiment, the inter-valve body spring 81 H suppresses the vibrational operation and noise Occurrence is suppressed.

  In the event of a failure such as disconnection of the coil 74 of the solenoid 71 or failure of the controller, the valve opening pressure of the compression pilot valve body 81 or the expansion pilot valve body 82 according to the compression spring 81 K and the inter-valve spring 81 H Therefore, it is possible to generate a damping force corresponding to the spring force.

  In this embodiment, with the normally closed valve type, the variable range of damping force can be made large in both the extension stroke and the compression stroke. Further, at the time of transition from the extension stroke to the compression stroke, or at the reverse transition thereof, the expansion side pilot valve body 82 is less likely to vibrate, and a low noise shock absorber 1 can be provided.

  As shown in FIG. 12, a valve spring 82H may be disposed between the piston bolt 5 and the extension pilot valve body 82 instead of the valve spring (inter-valve body spring) 81H. One end of the valve spring 82 H is supported by the piston bolt 5, and the other end is in contact with the extension pilot valve body 82. Therefore, the expansion side spring 82H exerts an urging force in the valve closing direction on the expansion side pilot valve body 82, and does not exert an urging force on the contraction side pilot valve body 81. From such a configuration, the valve spring 82H may be referred to as an expansion side spring 82H.

  In the configuration using the extension side spring 82H as the valve spring, the spring force of the extension side spring 82H can be set specifically to the biasing force of the extension side pilot valve body 82, and the design freedom can be increased. It becomes.

  Further, when the inter-valve spring 81 H and the extension spring 82 H are disposed on the compression pilot valve 81 side with respect to the extension pilot valve 82, they are disposed radially outward of the compression pilot valve 81. Thus, the inter-valve spring 81H and the extension-side spring 82H can be disposed in a small space.

  In each embodiment, the valve springs 59, 81H, 82H bias the extension side pilot valve body (second valve body) 82 in one direction of the on-off valve direction, and maintain the extension side pilot valve body 82 in a stable state. Do. As a result, in the shock absorber 1, the expansion side pilot valve body 82 hardly vibrates, and low noise can be realized.

  In the hydraulic shock absorber of Patent Document 1, the second valve body is configured to be inserted into the first valve body and operated, and there is a problem in improvement of responsiveness and durability. In the shock absorber 1 of each embodiment according to the present invention, the expansion side pilot valve body 82 is formed in a circular tubular shape (annular shape) in which the dimension (thickness dimension) in the central axial direction (opening / closing valve direction) is smaller than the diameter. A seat portion 82A is formed on the upper end side opening edge of the inner diameter portion, and a seating surface 81D of the compression side pilot valve body 81 abuts on the seat portion 82A. For this reason, the compression side pilot valve body 81 is not configured to be inserted and operated inside the extension side pilot valve body 82, and is advantageous in improving responsiveness and durability.

  The present invention is not limited to the above-described embodiments, but includes various modifications. For example, the embodiments described above are described in detail in order to explain the present invention in an easy-to-understand manner, and are not necessarily limited to those having all the configurations. Also, part of the configuration of one embodiment can be replaced with the configuration of another embodiment, and the configuration of another embodiment can be added to the configuration of one embodiment. In addition, with respect to a part of the configuration of each embodiment, it is possible to add, delete, and replace other configurations.

  Reference Signs List 1 shock absorber 2 cylinder 2 A cylinder upper chamber (first chamber) 2 B cylinder lower chamber (second chamber) 3 piston, 5 piston bolt (passage forming member, pilot valve accommodating member) 9: piston rod 15: extension side passage (first passage) 16: compression side passage (second passage) 20: extension side main valve (first main valve) 23: extension side back pressure chamber (first Back pressure chamber 28; extension side back pressure introducing valve (first back pressure introducing valve) 29 radial passage (common passage) 30 axial passage (common passage, large diameter axial passage portion) 36 ... Shrink side main valve (second main valve) 38 ... Shrink side back pressure chamber (second back pressure chamber) 43 ... Shrink side back pressure introduction valve (second back pressure introduction valve) 44 ... Radial direction passage ( Common passage), 48 ... axial passage (common passage, small diameter axial passage portion), 49 ... axial passage (common passage, Radial axial passage portion 58C: Seat portion of extension side pilot valve body 82 (second valve seat) 59: Valve spring 65A: Notch (orifice) 71: solenoid (actuator) 81: pilot side of pilot valve Body (first valve body) 81 F: fitting portion of contraction side pilot valve body 81 (expanded diameter portion) 81 H: inter-valve body spring (valve spring) 82: expansion side pilot valve body (second valve body) , 82A: Seat portion (first valve seat) of the compression side pilot valve body 81, 82H: extension side spring (valve spring).

Claims (7)

A cylinder in which the working fluid is sealed;
A piston slidably fitted inside the cylinder to divide the inside of the cylinder into a first chamber and a second chamber;
A piston rod having one end connected to the piston and the other end extending outward from the cylinder;
A first passage provided in the piston and flowing the working fluid of the first chamber to the second chamber in a stroke in which the volume of the first chamber decreases;
A second passage provided in the piston and flowing the working fluid of the second chamber to the first chamber in a stroke in which the volume of the second chamber decreases;
A first main valve for opening and closing the first passage;
A first back pressure chamber for adjusting an opening pressure of the first main valve;
A second main valve for opening and closing the second passage;
A second back pressure chamber for adjusting the valve opening pressure of the second main valve;
A common passage communicating the first back pressure chamber and the second back pressure chamber;
A pilot valve disposed inside the common passage to control the flow of the working fluid in the common passage;
An actuator controlling movement of the pilot valve;
Equipped with
The pilot valve is
A first valve body movably provided inside the common passage;
A second valve body provided with a first valve seat on which the first valve body is seated and movably provided inside the common passage;
A second valve seat on which the second valve body is seated;
A valve spring biasing the second valve body toward the first valve body or the second valve seat;
Have
The shock absorber, wherein the first valve body is biased toward the first valve seat by the actuator. In the shock absorber according to claim 1,
A passage component that constitutes the common passage;
The valve spring is provided on the side opposite to the first valve body with respect to the second valve body, and is provided between the passage component and the second valve body, and the second valve body is Shock absorber biased toward the first valve body. In the shock absorber according to claim 2,
The second valve body has an annular shape whose thickness dimension in the central axial direction is smaller than its diameter,
The shock absorber, wherein the first valve seat is formed on an end face of the first valve body in a central axial direction of the second valve body. In the shock absorber according to claim 3,
The shock absorber, wherein the valve spring is in contact with an end face side opposite to the end face of the second valve body. In the shock absorber according to claim 4,
The common passage includes an axial passage in which the pilot valve is disposed, a first radial passage communicating the axial passage and the first back pressure chamber via a first back pressure introducing valve, and the shaft. A second radial passage communicating the directional passage with the second back pressure chamber via a second back pressure introducing valve;
The axial passage is a large diameter axial passage portion where the second valve body is disposed, and a side where the first valve body is disposed relative to the large diameter axial passage portion with respect to the second valve seat And a small diameter axial passage portion having a diameter smaller than that of the large diameter axial passage portion,
A second radial passage is provided in the small diameter axial passage portion,
The first valve body has an enlarged diameter portion in which an orifice is formed in the middle of the central axis direction,
The shock absorber wherein the enlarged diameter portion of the first valve body is fitted to the small diameter axial passage portion in a state where there is no biasing force by the actuator. In the shock absorber according to claim 1,
The valve spring is provided between the first valve body and the second valve body, and urges the second valve body toward the second valve seat. In the shock absorber according to claim 1,
A passage component that constitutes the common passage;
The valve spring is provided on the same side as the first valve body with respect to the second valve body, and is provided between the passage component and the second valve body, and the second valve body is Shock absorber biased toward the two-valve seat.

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