Solenoids, solenoid valves, and shock absorbers

Abstract

To provide a solenoid, a solenoid valve using the solenoid, and a shock absorber capable of exerting sufficient thrust at low cost without causing an increase in size.SOLUTION: A solenoid 40 includes a coil 41, a first fixed iron core 43 arranged on one end side of the coil 41 in the axial direction, a second fixed iron core 44 arranged on the other end side of the coil 41 in the axial direction with a gap with the first fixed iron core 43, a cylindrical first movable iron core 45 arranged between the first fixed iron core 43 and the second fixed iron core 44, a second movable iron core 46 that has a bottomed tubular shape, and is slidably inserted into the first movable iron core 45 such that a bottom 46b faces the second fixed iron core 44 and is placed between the first fixed iron core 43 and the second fixed iron core 44, and a spring 47 that is interposed between the first movable iron core 45 and the first fixed iron core 43 and urges the first movable iron core 45 toward the second fixed iron core.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to a solenoid, a solenoid valve including a solenoid, and a shock absorber including a solenoid valve including a solenoid. [Background technology]

[0002] Generally, a solenoid has a coil and a movable core, and when electricity is applied to the coil, the movable core is attracted toward the fixed core, thereby driving the movable core. When a solenoid is used in a solenoid valve, the solenoid can adjust the valve opening pressure of the solenoid valve by changing the thrust force applied to the valve body of the solenoid valve when electricity is applied.

[0003] The solenoid valve is provided in the middle of a pilot passage that reduces the pressure upstream of the damping valve and directs it to the back pressure chamber to adjust the pressure in the back pressure chamber, which applies back pressure to the back of the damping valve provided in the piston of the shock absorber. In a shock absorber configured in this way, changing the thrust of the solenoid also changes the valve opening pressure of the solenoid valve, thereby controlling the pressure in the back pressure chamber. Changing the pressure in the back pressure chamber also changes the valve opening pressure of the damping valve, so by controlling the amount of current applied to the solenoid, it is possible to control the damping force generated when the shock absorber expands or contracts.

[0004] If a general solenoid is used for the solenoid valve of such a shock absorber, the damping force of the shock absorber can be adjusted by controlling the amount of current given to the solenoid as described above during normal operation when the solenoid can be energized, but during a failure when the solenoid cannot be energized, the solenoid cannot control the opening pressure of the solenoid. For this reason, in the shock absorber, a fail valve for setting the damping force of the shock absorber during a failure is connected in parallel to the solenoid valve, but if the fail valve opens during normal operation, the solenoid valve cannot control the back pressure. Therefore, it is necessary to make the opening pressure of the fail valve higher than the control range of the opening pressure of the solenoid valve during normal operation, and the damping force of the shock absorber during a failure may become excessive, which may impair the ride comfort of the vehicle.

[0005] In response to these problems, the applicant has developed an improved solenoid. The improved solenoid includes a coil, a first fixed core arranged at one axial end of the coil, a second fixed core arranged at the other axial end of the coil with a gap between it and the first fixed core, a first movable core arranged between the first and second fixed cores and attracted to the first fixed core when current is passed through the coil, a second movable core arranged between the first and second fixed cores and attracted to the second fixed core when current is passed through the coil, and a spring interposed between the first movable core and the first fixed core for urging the first movable core toward the second fixed core.

[0006] The improved solenoid configured as described above, when energized, attracts the first movable core toward the first fixed core, so that the biasing force of the spring does not act on the second movable core, and a force that attracts the second movable core toward the second fixed core acts on the valve body of the solenoid valve. In addition, in the conventional solenoid, when not energized, the first movable core is pressed against the second movable core by the biasing force of the spring, and the biasing force of the spring acts on the valve body of the solenoid valve via the second movable core. Therefore, the improved solenoid applies a thrust in the same direction to the valve body of the solenoid valve not only when energized but also when not energized, and the thrust at the time of failure can be set by the biasing force of the spring. Therefore, according to the improved solenoid, the valve opening pressure of the solenoid valve at the time of failure can be set by the biasing force of the solenoid spring, so that the damping force at the time of failure of the shock absorber can be optimized and there is no need to arrange a fail valve in parallel with the solenoid valve. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] JP 2019-160994 A Summary of the Invention [Problem to be solved by the invention]

[0008] However, in the improved solenoid, the non-magnetic filler ring provided on the inner periphery of the coil and the second fixed core are joined by brazing, which increases the processing costs.

[0009] In order to keep processing costs low, as shown in FIG. 8, a filler ring 202 can be pressed onto the outer periphery of the annular protrusion 201a of the second fixed core 201. However, in doing so, it is necessary to provide an annular recess 203b on the outer periphery of the bottom 203a of the second movable core 203 to avoid the protrusion 201a of the second fixed core 201. In order to ensure the cross-sectional area of ​​the magnetic path between the bottom 203a and the cylindrical portion 203c, the axial length of the bottom 203a of the second movable core 203 must be increased accordingly.

[0010] Here, the improved solenoid has two movable cores, the first movable core and the second movable core both being cylindrical with a bottom, and the first movable core is slidably inserted into the second movable core, and the first movable core and the second movable core form a magnetic path. Therefore, when a high current is passed through the solenoid and the second movable core and the first movable core are separated from each other to the maximum, if the overlap length between the two in the axial direction becomes short, the magnetic flux becomes saturated and sufficient thrust cannot be obtained, so it is necessary to ensure the axial length of the cylindrical portion 203c. For the above reasons, in order to reduce the cost of the solenoid, the axial length of the second movable core 203 must be increased, and the axial length of the solenoid must also be increased.

[0011] Therefore, in order to reduce the cost of the solenoid, it is necessary to increase the axial length of the solenoid. However, this increases the size of the solenoid, making it difficult to install it in applicable equipment such as a shock absorber, and there may be cases where the solenoid cannot be installed in the applicable equipment due to installation space constraints.

[0012] Thus, improved solenoids have a problem in that in order to reduce costs, they must be made larger in size in order to generate sufficient thrust.

[0013] Therefore, the object of the present invention is to provide a solenoid that can exert sufficient thrust at low cost and without increasing in size, to provide an electromagnetic valve that can adjust the valve opening pressure at low cost and without increasing in size, and to provide a shock absorber that can adjust the damping force at low cost and without increasing in size. [Means for solving the problem]

[0014] In order to solve the above-mentioned problems, the solenoid of the present invention comprises a coil, a first fixed core arranged at one axial end of the coil, a second fixed core arranged at the other axial end of the coil with a gap from the first fixed core, a cylindrical first movable core arranged between the first fixed core and the second fixed core and attracted to the first fixed core when current is passed through the coil, a cylindrical second movable core with a bottom, inserted freely slidably into the first movable core, arranged between the first fixed core and the second fixed core with its bottom facing the second fixed core, and attracted to the second fixed core when current is passed through the coil, and a spring interposed between the first movable core and the first fixed core for urging the first movable core toward the second fixed core.

[0015] In a solenoid configured in this manner, the first movable core and not the second movable core is arranged on the outer periphery, so magnetic flux saturation can be suppressed without increasing the axial length of the second movable core, and the length of the contact portion between the first movable core and the second movable core can be sufficiently secured even when the first movable core and the second movable core are at their farthest apart.

[0016] The solenoid is provided with a cylindrical filler ring disposed on the inner circumference of the coil and interposed between the first fixed core and the second fixed core, the first movable core is slidably inserted into the inner circumference of the filler ring, and the second fixed core is annular and press-fitted into the filler ring, and has a press-fit portion into which the second movable core is slidably inserted. R According to the solenoid configured in this manner, the filler ring can guide the axial movement of the first movable core and the second movable core, and the filler ring and the second fixed core can be integrated at low cost by press-fitting the press-fit portion into the filler ring.

[0017] Furthermore, in the solenoid, the filler ring is provided with a flange on its inner periphery that faces the press-fit portion in the axial direction, and a seal ring is provided between the flange and the press-fit portion to seal between the filler ring and the second fixed iron core. With a solenoid configured in this manner, the overall length of the press-fit portion can be shortened, and therefore the overall length of the solenoid can also be shortened.

[0018] A solenoid according to another invention has a cylindrical spring bearing connected to a first movable core, the first movable core having a sliding cylinder in sliding contact with the outer periphery of the second movable core and an annular bottom portion protruding from one end of the sliding cylinder toward the inner periphery, the spring bearing is cylindrical, one end of which is connected to the inner periphery of the annular bottom portion and has an annular spring support portion protruding inward from the inner periphery of the other end, one end of the spring abuts against the first fixed core and the other end is inserted into the spring bearing and abuts against the spring support portion. The axial movement of the second movable core is guided only by bringing the second movable core into sliding contact with the first movable core and the second fixed core. In addition, in a solenoid of another invention, the outer diameter of the second movable core is constant. In addition, a solenoid of another invention has a cylindrical filler ring arranged on the inner circumference of the coil and interposed between a first fixed iron core and a second fixed iron core, and the first movable iron core is slidably inserted into the inner circumference of the filler ring.

[0020] Furthermore, the solenoid valve may be a solenoid valve provided in the middle of the passage with a solenoid, equipped with a valve body that opens and closes the passage, and configured so that the solenoid applies a force that attracts the second movable iron core toward the second fixed iron core when current is applied to the coil to the valve body in a direction that closes the passage. With a solenoid valve configured in this manner, the valve opening pressure of the valve body can be adjusted using a low-cost, small-sized solenoid, and the valve opening pressure of the valve body in the event of a fail can be set by the biasing force of a spring.

[0021] The shock absorber may also include a cylinder, a rod inserted into the cylinder so as to be movable in the axial direction, a disk having a port through which liquid flows when the cylinder and the rod move relative to each other in the axial direction and a valve seat surrounding the port, a leaf valve that opens and closes the port by being seated on and off the valve seat, a pilot passage having a throttle provided therein and reducing and directing the pressure on the upstream side of the port to the back side of the leaf valve, a solenoid valve that controls the pressure on the back side of the leaf valve, and a solenoid that applies a thrust to the solenoid valve that attracts the second movable iron core toward the second fixed iron core when current is applied to the coil. According to the shock absorber configured in this manner, the pressure on the back side of the leaf valve can be adjusted by a solenoid valve that uses a low-cost and small solenoid, so that the damping force can be adjusted at low cost without increasing in size. According to the shock absorber configured in this manner, the pressure on the back side of the leaf valve can be set by setting the biasing force of the spring of the solenoid in the event of a failure, and the damping force generated by the shock absorber in the event of a failure can be optimized. Effect of the Invention

[0022] The solenoid of the present invention can provide sufficient thrust at low cost and without increasing in size. The solenoid valve of the present invention can adjust the valve opening pressure at low cost and without increasing in size. Furthermore, the shock absorber of the present invention can adjust the damping force at low cost and without increasing in size. [Brief description of the drawings]

[0023] [Figure 1] 1 is a vertical cross-sectional view showing a damping valve according to an embodiment of the present invention. [Diagram 2] 1 is a vertical cross-sectional view conceptually showing a shock absorber provided with a damping valve according to an embodiment of the present invention; [Diagram 3] FIG. 2 is an enlarged view of a valve portion of a damping valve according to an embodiment of the present invention. [Figure 4] 5 is a diagram showing characteristics of the biasing force of a leaf spring with respect to the amount of movement of a spool of a damping valve according to an embodiment of the present invention. FIG. [Diagram 5]FIG. 2 is an enlarged view of a solenoid portion of a damping valve according to an embodiment of the present invention. [Figure 6] 5 is a diagram showing characteristics of thrust generated by a solenoid relative to the amount of current applied to a solenoid of a damping valve according to an embodiment of the present invention. FIG. [Figure 7] 5 is a diagram showing the damping characteristics of a shock absorber to which a damping valve according to an embodiment of the present invention is applied. FIG. [Figure 8] FIG. 1 is a diagram showing a structure of a solenoid for reducing the cost of a conventional solenoid. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0024] The present invention will be described below based on one embodiment shown in the drawings. As shown in Figures 1 and 5, a solenoid 40 in one embodiment includes a coil 41, a first fixed core 43 arranged on one axial end side of the coil 41, a second fixed core 44 arranged on the other axial end side of the coil with a gap from the first fixed core 43, a cylindrical first movable core 45 arranged between the first fixed core 43 and the second fixed core 44, a bottomed cylindrical second movable core 46 slidably inserted into the first movable core 45, and a spring 47 interposed between the first movable core 45 and the first fixed core 43 to bias the first movable core 45 toward the second fixed core 44, and is applied to the solenoid valve 24 in a shock absorber 100.

[0025] The solenoid valve 24 is used to adjust the back pressure acting on the leaf valve 3 of the damping valve 1 in the shock absorber 100, and the amount of electricity supplied to the solenoid 40 is adjusted to adjust the magnitude of the back pressure.

[0026] 1, the damping valve 1 and shock absorber 100 each equipped with a solenoid 40 and a solenoid valve 24 to which the solenoid 40 is applied will be described in detail. First, as shown in Fig. 1, the damping valve 1 comprises a disk 2 having a port 2a and a valve seat 2b surrounding the port 2a, a leaf valve 3 whose front side is seated on and separated from the valve seat 2b to open and close the port 2a, a cylindrical housing 4 provided on the back side of the leaf valve 3, an annular spool 6 that abuts against the back side of the leaf valve 3 and is inserted slidably on the inner periphery of the housing 4 to form a back pressure chamber 5 that applies back pressure inwardly to the leaf valve 3 together with the housing 4, and The valve is provided with an annular spring support portion 4g which faces the back pressure chamber 5 on the back side and has an outer diameter smaller than that of the spool 6, an annular leaf spring 7 which is interposed between the spring support portion 4g and one end of the spool 6 which is the end opposite the leaf valve and which urges the spool 6 in a direction to abut against the leaf valve 3, a valve retaining member 10, a pilot passage 23 which introduces pressure on the upstream side of the port 2a to the back pressure chamber 5, a solenoid valve 24 provided in the pilot passage 23, and a solenoid 40 which applies thrust to the solenoid valve.

[0027] This damping valve 1 is applied to a shock absorber 100, which generates a damping force mainly by providing resistance to a liquid passing through the port 2a during expansion and contraction.

[0028] 2, the shock absorber 100 to which the damping valve 1 is applied includes a cylinder 101, a piston 102 slidably inserted into the cylinder 101, a rod 103 moved and inserted into the cylinder 101 and connected to the piston 102, an extension side chamber 104 and a compression side chamber 105 partitioned by the piston 102 inserted into the cylinder 101, an intermediate cylinder 107 covering the outer periphery of the cylinder 101 to form a discharge passage 106 between the cylinder 101, and an outer cylinder 109 covering the outer periphery of the intermediate cylinder 107 to form a reservoir 108 between the intermediate cylinder 107. The extension side chamber 104 and the compression side chamber 105 are filled with liquid, and the reservoir 108 is filled with gas in addition to the liquid stored therein. In the shock absorber 100 of this embodiment, hydraulic oil is used as the liquid, but any liquid that can exert a damping force using the damping valve 1 can be used other than hydraulic oil.

[0029] In the case of this shock absorber 100, there is provided a suction passage 110 that allows only the flow of hydraulic oil from the reservoir 108 to the compression side chamber 105, and a straightening passage 111 that is provided in the piston 102 and allows only the flow of hydraulic oil from the compression side chamber 105 to the extension side chamber 104. The discharge passage 106 connects the extension side chamber 104 to the reservoir 108, and the damping valve 1 is provided in the middle of the discharge passage 106, connecting a port 2a to the discharge passage 106.

[0030] 2, the compression side chamber 105 is compressed, and the hydraulic oil in the compression side chamber 105 moves to the expansion side chamber 104 via the flow straightening passage 111. During this compression operation, the rod 103 enters the cylinder 101, so that the hydraulic oil in the cylinder 101 is in an excess amount by the volume of the rod, and the excess hydraulic oil is pushed out of the cylinder 101 and discharged to the reservoir 108 via the discharge passage 106. The shock absorber 100 provides resistance to the flow of hydraulic oil passing through the discharge passage 106 and moving to the reservoir 108 with the damping valve 1, thereby increasing the pressure in the cylinder 101 and exerting the compression side damping force.

[0031] Conversely, when the shock absorber 100 performs an extension operation, the piston 102 moves upward in FIG. 2, the expansion-side chamber 104 is compressed, and the hydraulic oil in the expansion-side chamber 104 moves to the reservoir 108 via the discharge passage 106. During this extension operation, the piston 102 moves upward, the volume of the compression-side chamber 105 expands, and hydraulic oil corresponding to this expansion is supplied from the reservoir 108 via the suction passage 110. Then, the shock absorber 100 provides resistance to the flow of hydraulic oil passing through the discharge passage 106 and moving to the reservoir 108 by the damping valve 1, thereby increasing the pressure in the expansion-side chamber 104 and exerting the extension-side damping force.

[0032] As can be understood from the above, when the shock absorber 100 performs an expansion / contraction operation, the hydraulic oil is always discharged from inside the cylinder 101 through the discharge passage 106 to the reservoir 108, and the shock absorber is configured as a uniflow type shock absorber in which the hydraulic oil circulates in one direction through the compression-side chamber 105, the extension-side chamber 104, and the reservoir 108 in that order, and both the expansion and compression damping forces are generated by a single damping valve 1.

[0033] As described above, the damping valve 1 includes a disk 2 having a port 2a and a valve seat 2b surrounding the port 2a, and a front side of the disk 2 is seated on and separated from the valve seat 2b. Let me In addition to the leaf valve 3 that opens and closes the port 2a, a cylindrical housing 4 provided on the back side of the leaf valve 3, an annular spool 6 that abuts against the back side of the leaf valve 3 and is inserted slidably into the inner periphery of the housing 4 to form, together with the housing 4, a back pressure chamber 5 that applies back pressure inward to the leaf valve 3, an annular spring support portion 4g that is on the back side of the leaf valve 3 and faces the back pressure chamber 5 and has an outer diameter smaller than that of the spool 6, and an annular leaf spring 7 that is interposed between one end of the spool 6 that is the end opposite the leaf valve and the spring support portion 4g to urge the spool 6 in a direction to abut against the leaf valve 3, in this embodiment, there is also provided a valve holding member 10 that is fitted into a sleeve 107a provided in an opening of an intermediate cylinder 107, a pilot passage 23 that leads the pressure on the upstream side of the port 2a to the back pressure chamber 5 inside the valve holding member 10 and the housing 4, a solenoid valve 24 provided in the pilot passage 23, and a solenoid 40 that provides thrust to the solenoid valve.

[0034] Hereinafter, each part of the damping valve 1 will be described in detail. As shown in Fig. 3, the valve holding member 10 is configured to include a large-diameter base portion 10a that is fitted into the sleeve 107a, a shaft portion 10b that protrudes from the base portion 10a to the right in Fig. 3 and has a screw portion (not shown) on the outer periphery at the right end in Fig. 3, a hollow portion 10c that is formed to penetrate the base portion 10a and the shaft portion 10b in the axial direction and forms a part of the pilot passage 23, an orifice 10d as a throttle provided midway through the hollow portion 10c, and a plurality of passages 10e that penetrate the base portion 10a from the left end to the right end in Fig. 3.

[0035] As described above, the passage 10e passes through the base 10a and communicates with the hollow portion 10c, and is further communicated with the inside of the expansion-side chamber 104 through the discharge passage 106 formed by the intermediate tube 107 through the hollow portion 10c. In addition, the opening of the passage 10e on the right end side of the base 10a in FIG. 3 is communicated with the reservoir 108. That is, in the case of this shock absorber 100, the hydraulic oil is discharged from the expansion-side chamber 104 to the reservoir 108 through the discharge passage 106 and the passage 10e during expansion and contraction, and the upstream of the passage 10e is the expansion-side chamber 104. In addition, the opening of the hollow portion 10c on the left end side in FIG. 3 is also communicated with the inside of the expansion-side chamber 104 through the discharge passage 106, similar to the passage 10e.

[0036] A small diameter portion 10g, which is formed by reducing the diameter of the left side of the base 10a of the valve retaining member 10 in FIG. 3, is fitted into the sleeve 107a, and a seal ring 10f is attached to the outer periphery of this small diameter portion 10g to seal between it and the sleeve 107a, so that the discharge passage 106 will not communicate with the reservoir 108 via the outer periphery of the base 10a.

[0037] Next, a disk 2 that opens and closes the passage 10e by being seated on the base 10a is stacked on the right end of the base 10a of the valve holding member 10 in FIG. 3. The disk 2 is annular and has a plurality of ports 2a penetrating the thickness in the axial direction, and an annular valve seat 2b that is provided on the back side opposite the valve holding member and surrounds the outer periphery of the ports 2a and protrudes to the back side. The disk 2 further has an annular protrusion 2c that protrudes toward the base 10a from the end facing the base 10a of the valve holding member 10. The annular protrusion 2c faces the outer periphery of the passage 10e in the base 10a, and when the disk 2 abuts against the base 10a, the annular protrusion 2c is seated on the outer periphery of the passage 10e in the base 10a. Therefore, when the disk 2 abuts against the base 10a, the disk 2 closes the outlet end of the passage 10e. Also, port 2a is designed to provide resistance to the flow of hydraulic oil passing through it, and as will be described in detail later, when hydraulic oil that has passed through passage 10e passes through port 2a and moves to the back side of disk 2, a difference in pressure is generated between the valve holding member side, which is the front side of disk 2, and the back side. Note that, in damping valve 1 of this embodiment, disc 2 is provided with annular protrusion 2c, but a valve seat surrounding the outer periphery of passage 10e may be provided in base 10a of valve holding member 10.

[0038] The disk 2 is slidably mounted on the outer periphery of an annular spacer 25 mounted on the outer periphery of the shaft portion 10b of the valve holding member 10. The axial thickness of the spacer 25 is greater than the axial thickness of the inner periphery of the disk 2, and the disk 2 is capable of moving in the axial direction, ie, the left-right direction in FIG. 3, on the outer periphery of the spacer 25. Therefore, the disk 2 is assembled in a floating state to the valve holding member 10, and can be seated on and removed from the base portion 10a by moving toward and away from the valve holding member 10, and opens the passage 10e when it is removed from the base portion 10a. The valve seat 2b is provided with a notched orifice 2d. The orifice may be provided in the valve holding member 10 or the annular protruding portion 2c of the disk 2 instead of the notched orifice 2d.

[0039] Furthermore, leaf valves 3 are stacked on the back side of the disk 2. The leaf valves 3 are stacked leaf valves formed by stacking a plurality of annular plates, and the inner periphery of the leaf valves 3 is assembled to the shaft portion 10b and is sandwiched between a spacer 25 and a housing 4 which is screwed to the shaft portion 10b. Therefore, the leaf valves 3 are allowed to deflect on the outer periphery side so that they can be seated on and removed from the valve seat 2b of the disk 2. The outer diameter of the annular plates in the leaf valves 3 becomes gradually smaller as they are stacked toward the back side.

[0040] The inner circumference of the leaf valve 3 is laminated on the spacer 25, and the outer circumference is seated on the valve seat 2b protruding from the back surface of the disk 2 toward the leaf valve 3 side, so that there is a space between the leaf valve 3 and the disk 2, and this space forms the intermediate chamber 9. The intermediate chamber 9 is connected to the passage 10e via the port 2a. When the leaf valve 3 is deflected by the pressure acting on the intermediate chamber 9 via the port 2a and lifts off the valve seat 2b, an annular gap is formed between the leaf valve 3 and the disk 2, and the hydraulic oil that has passed through the passage 10e and the port 2a can move to the reservoir 108 through between the leaf valve 3 and the disk 2. In other words, even if the disk 2 is seated on the base 10a, when the leaf valve 3 is deflected and lifts off the valve seat 2b, the port 2a is opened and the hydraulic oil can move from the extension side chamber 104 to the reservoir 108.

[0041] Furthermore, when the leaf valve 3 bends and the disk 2 is pushed up by the pressure from the passage 10e, the entire disk 2 slides on the spacer 25 and leaves the base 10a, and in this case, the hydraulic oil that has passed through the passage 10e is discharged to the reservoir 108 through the annular gap generated between the disk 2 and the base 10a. Note that the leaf valve 3 is configured as a laminated leaf valve in which a plurality of annular plates are laminated, but the number of annular plates is arbitrary.

[0042] 1, which is the tip of the shaft portion 10b, the housing 4 is screwed in. Then, the spacer 25 and the leaf valve 3 assembled to the shaft portion 10b are sandwiched and fixed between the base portion 10a of the valve holding member 10 and the housing 4. As described above, the disk 2 attached to the outer periphery of the spacer 25 is in a floating state fixed to the outer periphery of the spacer 25 and is movable in the axial direction.

[0043] As shown in FIG. 3, the housing 4 comprises an inner tube 4a having a threaded portion (not shown) on its inner periphery and screwed onto the shaft portion 10b of the valve holding member 10, an outer tube 4b facing the inner tube 4a with an annular gap therebetween, a flange-shaped bottom portion 4c protruding radially from the outer periphery of the right end of the inner tube 4a in FIG. 3 and connected to the right end of the outer tube 4b in FIG. 3, a cylindrical socket 4d rising from the side opposite the inner tube of the bottom portion 4c and having a threaded portion (not shown) on its outer periphery, a hole 4e penetrating the bottom portion 4c and communicating the annular gap between the inner tube 4a and the outer tube 4b with the inside of the socket 4d, and a notched groove 4f provided along the axial direction on the outer periphery of the socket 4d.

[0044] When the inner cylinder 4a of the housing 4 is screwed onto the shaft portion 10b of the valve holding member 10, it cooperates with the base portion 10a of the valve holding member 10 to sandwich the spacer 25 and the leaf valve 3. In addition, the outer diameter of the outer periphery of the inner cylinder 4a of the housing 4 at the right end in FIG. 3, which is the base end, is increased to form a step, and a spring support portion 4g having an annular surface facing the back surface of the leaf valve 3 is provided at the step. This spring support portion 4g functions as a spring bearing that supports the inner periphery of the leaf spring 7. In addition, the inside of the housing 4 is connected to the hollow portion 10c of the valve holding member 10, and is connected to the expansion-side chamber 104, which is upstream of the passage 10e, via the orifice 10d.

[0045] As shown in FIG. 3, the spool 6 is slidably inserted into the inner circumference of the outer cylinder 4b. The spool 6 is annular, and has an outer periphery at one end (right end in FIG. 3) opposite the leaf valve as one end outer periphery 6a, a tapered portion 6b inclined toward the other end on the inside of the one end outer periphery 6a, and an outer periphery at the other end (left end in FIG. 3) opposite the leaf valve as other end outer periphery 6c, a tapered portion 6d inclined toward the one end on the inside of the other end outer periphery 6c. As shown in FIG. 3, the spool 6 has a plurality of grooves 6e penetrating the one end outer periphery 6a in the radial direction. In the damping valve 1 of this embodiment, three grooves 6e are provided at equal intervals in the circumferential direction of the spool 6.

[0046] The spool 6 is movable in the axial direction relative to the housing 4, and the other end outer periphery 6c is in contact with the outer periphery of the back surface of the leaf valve 3, forming a back pressure chamber 5 in cooperation with the housing 4. The back pressure chamber 5 is connected to the inside of the socket 4d via a hole 4e provided in the bottom 4c of the housing 4. As described above, since the inside of the housing 4 is connected to the inside of the expansion-side chamber 104, the hydraulic oil discharged from the expansion-side chamber 104 is led to the back pressure chamber 5 via the orifice 10d and the hole 4e. In this way, the pressure upstream of the passage 10e is reduced by the orifice 10d and introduced into the back pressure chamber 5.

[0047] In addition, the spool 6 has a tapered portion 6d on the inside of the outer periphery 6c at the other end of the spool 6 with which the outer periphery of the leaf valve 3 abuts, so that the spool 6 does not interfere with the leaf valve 3 even when it is used as a laminated leaf valve whose outer diameter gradually decreases toward the back side. The number and outer diameter of the annular plates in the leaf valve 3 can be arbitrarily changed in design, but by providing the tapered portion 6d at the other end of the spool 6, which is the leaf valve side end, the freedom in selecting the number of annular plates of the leaf valve 3 and the size of the outer diameter is improved.

[0048] In the damping valve 1 of this embodiment, the leaf spring 7 is an annular disc spring, and its inner periphery on the side opposite to the leaf valve is supported by a spring support portion 4g provided in the housing 4, and its outer periphery on the leaf valve side is supported by an outer peripheral portion 6a at one end of the spool 6. The outer diameter of the spring support portion 4g is smaller than the inner diameter of the spool 6, and in a state in which the leaf valve 3 is seated on the valve seat 2b of the disk 2, the disk 2 is seated on the base portion 10a of the valve holding member 10, and the spool 6 is in contact with the leaf valve 3, the support surface of the leaf spring 7 of the spring support portion 4g is disposed closer to the leaf valve side than the support surface of the leaf spring 7 of the outer peripheral portion 6a at one end of the spool 6 in the axial direction of the spool 6. That is, in FIG. 3, the spring support portion 4g of the housing 4 is disposed to the left of the outer peripheral portion 6a at one end of the spool 6.

[0049] Therefore, the leaf spring 7 is interposed between the spool 6 and the spring support portion 4g in a bent state after being given an initial deflection, and constantly urges the spool 6 in a direction to abut against the leaf valve 3. The amount of initial deflection of the leaf spring 7 can be set by setting the axial length of the spool 6 and the axial position of the spring support portion 4g. Since the leaf spring 7 must constantly urge the spool 6 so as not to move away from the leaf valve 3, it is sufficient to set the spring support portion 4g of the housing 4 to be closer to the leaf valve 3 in the axial direction than the outer circumferential portion 6a of one end of the spool 6. However, since the urging force of the leaf spring 7 affects the valve opening pressure of the damping valve 1, it is preferable that the urging force with which the leaf spring 7 urges the spool 6 be as small as possible. Therefore, the initial amount of deflection of the leaf spring 7 can be set by setting the axial length of the spool 6 and the axial position of the spring support portion 4g. of It is preferable to make it smaller.

[0050] Also, only the inner periphery of the leaf spring 7 on the side opposite the leaf valve abuts against the spring support portion 4g that faces the back surface of the leaf valve 3, and the inner periphery of the leaf spring 7 is not fixedly supported by the housing 4. Therefore, when the spool 6 moves in the axial direction away from the disk 2, the biasing force applied to the spool 6 by the leaf spring 7 that is not fixedly supported in this manner is smaller than the biasing force of the leaf spring when fixed to the inner periphery. Therefore, when a structure in which the leaf spring 7 is supported by the spring support portion 4g in this manner is adopted, the apparent spring constant of the leaf spring 7 is lowered, and therefore it is possible to suppress an increase in the biasing force applied to the spool 6 by the leaf spring 7 when the spool 6 moves in the direction away from the disk 2.

[0051] Furthermore, since the tapered portion 6b is provided on the inside of the one end outer periphery 6a of the spool 6, the inner diameter of the one end outer periphery 6a can be increased. The support diameter on the outer periphery side of the leaf spring 7 is determined by the inner diameter of the one end outer periphery 6a of the spool 6, and the larger the support diameter, the more the amount of deflection of the leaf spring 7 accompanying the movement of the spool 6 can be reduced. Therefore, by providing the tapered portion 6b on the inside of the one end outer periphery 6a of the spool 6 in this way, the apparent spring constant of the leaf spring 7 can be reduced, and therefore an increase in the biasing force that the leaf spring 7 applies to the spool 6 when the spool 6 moves in a direction away from the disk 2 can be suppressed.

[0052] In addition, a groove 6e is provided on the outer periphery 6a at one end of the spool 6, and even if the leaf spring 7 does not have any holes or grooves, the groove 6e connects the chamber on the leaf valve side of the leaf spring 7 on the left side in FIG. 3 with the chamber on the opposite side of the leaf valve side of the leaf spring 7 on the right side in FIG. 3, so that the leaf spring 7 does not divide the back pressure chamber 5. The groove 6e is provided so as to ensure a flow area that does not cause a pressure difference between the chamber on the leaf valve side of the leaf spring 7 and the chamber on the opposite side of the leaf valve side of the leaf spring 7 in the back pressure chamber 5. In addition, as shown in FIG. 4, by setting the circumferential width of the groove 6e, the characteristics of the magnitude of the biasing force that the leaf spring 7 applies to the spool 6 relative to the amount of movement of the spool 6 can be changed. When the width of the groove 6e is narrowed, the apparent spring constant of the leaf spring 7 tends to increase, as shown by the characteristic line A in FIG. 4, and the linear region (the region in which the biasing force of the leaf spring 7 is proportional to the amount of movement of the spool 6) that appears in the middle of the characteristic line A becomes narrower. When the width of the groove 6e is widened, as shown by characteristic line B in Fig. 4, the apparent spring constant of the leaf spring 7 tends to become smaller and the linear region (region in which the biasing force of the leaf spring 7 is proportional to the amount of movement of the spool 6) that appears on the middle of characteristic line B becomes wider. Since it is necessary to secure the flow area of ​​the groove 6e as described above, if it is desired to narrow the width of the groove 6e, the number of grooves 6e provided should be increased. Many If the width of the groove 6e is to be increased, the number of grooves 6e can be reduced. Therefore, the characteristics of the biasing force that the leaf spring 7 should impart to the spool 6 can be determined according to the required specifications of the damping valve 1, and the number and width of the grooves 6e can be appropriately set. Note that instead of providing the grooves 6e in the spool 6 to avoid the division of the back pressure chamber 5, the leaf spring 7 may be a leaf spring with a hole.

[0053] As described above, the hydraulic oil discharged from the expansion-side chamber 104 is guided to the back pressure chamber 5 through the orifice 10d and the hole 4e. Attached Leaf spring 7 Attached In addition to the force, the internal pressure of the back pressure chamber 5 presses the leaf valve 3 against the disk 2. AttachedThat is, when the shock absorber 100 expands or contracts, the pressure in the expansion-side chamber 104 acts on the disk 2 from the front side through the passage 10e, and the internal pressure of the back pressure chamber 5 and the pressure of the leaf spring 7 act on the disk 2 from the rear side through the leaf valve 3. Attached The forces will come into play.

[0054] A force obtained by multiplying a back pressure-receiving area, calculated by subtracting the area of ​​a circle whose diameter is the outside diameter of the smallest-diameter annular plate stacked on the top of the leaf valve 3, from the area of ​​a circle whose diameter is the outside diameter of the spool 6, by the pressure of the back pressure chamber 5, acts on the leaf valve 3 to press it against the disk 2, and a force obtained by multiplying a front pressure-receiving area, calculated by subtracting the area of ​​a circle whose diameter is the outside diameter of the spacer 25 from the area of ​​a circle whose diameter is the inside diameter of the valve seat 2b, by the pressure of the intermediate chamber 9, acts on the leaf valve 3 in a direction moving it away from the disk 2. Therefore, the ratio of the back pressure-receiving area to the front pressure-receiving area of ​​the leaf valve 3 determines the pressure boost ratio, which is the ratio of the valve opening pressure of the leaf valve 3 to the pressure in the back pressure chamber 5.

[0055] Then, the pressure in the intermediate chamber 9 increases due to the pressure in the expansion-side chamber 104, and the force that tries to bend the outer periphery of the leaf valve 3 to the right in FIG. 3 is generated by the internal pressure of the back pressure chamber 5 and the leaf spring 7. AttachedWhen the force overcomes, the leaf valve 3 is deflected and lifted off the valve seat 2b, forming a gap between the leaf valve 3 and the disk 2, and opening the passage 10e. In this embodiment, the inner diameter of the valve seat 2b is made larger than the inner diameter of the annular protrusion 2c, and a difference is provided between the pressure receiving area of ​​the disk 2 receiving the pressure on the passage 10e side and the pressure receiving area of ​​the disk 2 receiving the pressure on the intermediate chamber 9 side, and the disk 2 remains seated on the base 10a unless the pressure difference generated by the port 2a reaches the valve opening pressure that lifts the disk 2 off the base 10a of the valve holding member 10. On the other hand, when the leaf valve 3 is deflected and in an open state, and the pressure difference generated by the port 2a reaches the valve opening pressure that lifts the disk 2 off the base 10a, the disk 2 also lifts off the base 10a, opening the passage 10e. That is, the pressure boost ratio in the leaf valve 3 is set to be smaller than the pressure boost ratio in the disk 2, which is the ratio of the valve opening pressure of the disk 2 to the pressure in the intermediate chamber 9, so that the pressure in the expansion-side chamber 104 when the leaf valve 3 opens is lower than the pressure in the expansion-side chamber 104 when the disk 2 opens. That is, the valve opening pressure of the leaf valve 3 is set to be lower than the valve opening pressure of the disk 2.

[0056] Next, a cylindrical valve seat member 21 is accommodated inside the socket 4d in the housing 4 and the right end of the inner cylinder 4a in Fig. 3. The valve seat member 21 is configured to include a bottomed cylindrical small diameter cylinder portion 21a, a flange portion 21b protruding outward from the outer periphery of the end portion, which is the right end in Fig. 3, of the small diameter cylinder portion 21a, a large diameter cylinder portion 21c extending from the outer periphery of the flange portion 21b toward the opposite side to the small diameter cylinder portion 21a, a through hole 21d opening obliquely from the side of the small diameter cylinder portion 21a toward the inner periphery of the flange portion 21b, a notch 21e penetrating the large diameter cylinder portion 21c in the radial direction to communicate the inside and outside of the large diameter cylinder portion 21c, and an annular valve seat 21f protruding in the axial direction from the inner periphery of the right end of the flange portion 21b in Fig. 3.

[0057] The valve seat member 21 is accommodated in the housing 4 with the large diameter cylindrical portion 21c fitted into the socket 4d of the housing 4. The inside of the valve seat member 21 is communicated with the reservoir 108 via the notch 21e and a notched groove 4f provided in the socket 4d. The outer diameter of the small diameter cylindrical portion 21a is smaller than the inner diameter of the inner cylinder 4a of the housing 4, and the inside of the valve seat member 21 is communicated with the expansion-side chamber 104 via the through hole 21d, the hollow portion 10c of the valve holding member 10, and the orifice 10d.

[0058] Next, the valve body 22 is slidably inserted into the small diameter cylindrical portion 21a of the valve seat member 21. More specifically, the valve body 22 is configured to include a small diameter portion 22a on the left end side in Fig. 3 on the valve seat member side slidably inserted into the small diameter cylindrical portion 21a, a large diameter portion 22b on the right end side in Fig. 3 on the opposite side to the valve seat member, an annular recess 22c provided between the small diameter portion 22a and the large diameter portion 22b, a flange-shaped spring receiving portion 22d provided on the outer periphery of the opposite side end to the valve seat member, a communication passage 22e penetrating from the front end to the rear end of the valve body 22, and an orifice 22f provided in the middle of the communication passage 22e.

[0059] Furthermore, when the valve body 22 moves axially relative to the valve seat member 21 within the allowable range, the recess 22c of the valve body 22 always faces the through hole 21d so that the valve body 22 does not block the through hole 21d.

[0060] As described above, the valve body 22 has a larger outer diameter on the side opposite the valve seat member, across the recess 22c, and is provided with an annular valve portion 22g facing the valve seat 21f of the valve seat member 21 at the left end of the large diameter portion 22b in Figure 3. The valve body 22 moves in the axial direction relative to the valve seat member 21, so that the valve portion 22g is seated on and separated from the valve seat 21f.

[0061] Furthermore, between the spring receiving portion 22d and the flange portion 21b, the valve body 22 is Attached The valve body 22 is always biased toward the opposite side to the valve seat member by the coil spring 33. AttachedIn this manner, the valve body 22 is biased by the coil spring 33 in a direction away from the valve seat member 21, while being biased by the solenoid 40. Raben It is adapted to receive a thrust in the direction of sitting on the seat member 21.

[0062] In this manner, the valve body 22, the valve seat member 21, the coil spring 33, and the solenoid 40 constitute the solenoid valve 24, and the solenoid valve 24 is closed when the valve portion 22g is seated on the valve seat 21f. In the closed state, the solenoid valve 24 cuts off communication between the hollow portion 10c of the valve holding member 10 and the inside of the valve seat member 21, and in the open state, the hollow portion 10c communicates with the inside of the valve seat member 21. Therefore, when the solenoid valve 24 opens, the expansion-side chamber 104 communicates with the reservoir 108 via the hollow portion 10c, the orifice 10d, the through hole 21d, the inside of the valve seat member 21, the notch 21e, and the notch groove 4f. In this manner, in this embodiment, the hollow portion 10c, the orifice 10d, the through hole 21d, the inside of the valve seat member 21, the notch 21e, and the notch groove 4f form the pilot passage 23. The pilot passage 23 downstream of the orifice 10d communicates with the back pressure chamber 5 via a hole 4e in the housing 4, and the pressure downstream of the orifice 10d of the pilot passage 23 can be adjusted by controlling the valve opening pressure of the solenoid valve 24.

[0063] The valve opening pressure of the solenoid valve 24 is controlled by a solenoid 40, which will be described later, and the pressure in the back pressure chamber 5, which is the pressure at the back surface of the leaf valve 3, can be adjusted by the amount of current supplied to the solenoid 40. Since the pressure in the back pressure chamber 5 acts on the back surface of the leaf valve 3, in the damping valve 1 of this embodiment, the valve opening pressure of the leaf valve 3 can be adjusted by adjusting the amount of current supplied to the solenoid 40, and as a result, the damping force generated by the shock absorber 100 can be changed between large and small.

[0064] In this case, the coil spring 33 is used to move the valve body 22 in a direction away from the valve seat member 21. Attached In addition to the coil spring 33, Attached The valve body 22 may be made of an elastic material capable of exerting a force. Furthermore, a plunger 34 is fitted into the large diameter portion 22b of the valve body 22.

[0065] Furthermore, when the valve element 22 is inserted into the small diameter cylindrical portion 21a of the valve seat member 21, a space 26 is formed inside the small diameter cylindrical portion 21a on the tip side of the through hole 21d. This space 26 is in communication with the outside of the solenoid valve 24 via a communication passage 22e and an orifice 22f provided in the valve element 22, and a through hole 34a provided in the plunger 34. As a result, when the valve element 22 moves in the axial direction, which is the left-right direction in FIG. 1, relative to the valve seat member 21, the space 26 functions as a dashpot to suppress abrupt displacement of the valve element 22 and to suppress vibrational movement of the valve element 22.

[0066] Each part of the damping valve 1 configured in this manner is housed within a sleeve 109a attached to an opening provided in the outer cylinder 109 of the shock absorber 100, and is fixed to the shock absorber 100 by screwing the solenoid 40 into a nut 120 rotatably attached to the sleeve 109a.

[0067] As shown in FIG. 5, the solenoid 40 is configured to include a coil 41, a first fixed core 43 arranged at one axial end of the coil 41, a second fixed core 44 arranged at the other axial end of the coil 41 with a gap between it and the first fixed core 43, a cylindrical first movable core 45 arranged between the first fixed core 43 and the second fixed core 44 and attracted to the first fixed core 43 when current is passed through the coil 41, a bottomed cylindrical second movable core 46 that is slidably inserted into the first movable core 45 and arranged between the first fixed core 43 and the second fixed core 44 with a bottom 46b facing the second fixed core 44, and attracted to the second fixed core 44 when current is passed through the coil 41, and a spring 47 interposed between the first movable core 45 and the first fixed core 43 to urge the first movable core 45 toward the second fixed core.

[0068] The coil 41 is cylindrical and resin-molded, and is disposed on the outer periphery of the first movable core 45 and the second movable core 46. A cylindrical filler ring 42 made of a non-magnetic material is fitted on the inner periphery of the coil 41. The filler ring 42 has an annular flange 42a that protrudes inward from the inner periphery on the left end side in Fig. 5, and an annular groove 42b provided on the inner periphery on the right end side in Fig. 5.

[0069] 5, which is one end of the coil 41, and is fitted into the inner periphery of the right end of the filler ring 42 in Fig. 5. Specifically, the first fixed core 43 is made of a magnetic material, and includes a disk-shaped base 43a that comes into contact with the right end of the resin-molded coil 41 in Fig. 5, and an annular fitting portion 43b that rises from the base 43a and is fitted into the inner periphery of the filler ring 42.

[0070] 5 which is the other end of the coil 41, and is press-fitted into the inner periphery of the left end of the filler ring 42 in Fig. 5 with a gap between it and the first fixed core 43. Specifically, the second fixed core 44 is made of a magnetic material, and includes an annular base 44a that abuts against the left end of the resin-molded coil 41 in Fig. 5, a cylindrical case portion 44b that rises from the outer periphery of the base 44a, and a cylindrical press-fit portion 44c that rises from the inner periphery side of the base 44a and is press-fitted into the inner periphery of the filler ring 42.

[0071] The coil 41 and the filler ring 42 fitted to the inner circumference of the coil 41 are accommodated in the inner circumference of the case portion 44b, and the first stationary core 43 is accommodated in the inner circumference of the right end side of the case portion 44b in FIG. 5. The first stationary core 43 is gripped and fixed to the case portion 44b by crimping the right end of the case portion 44b in FIG. 5 from the outer circumference. When the first stationary core 43 is fixed to the case portion 44b, the coil 41 and the filler ring 42 are sandwiched between the base 43a of the first stationary core 43 and the base 44a of the second stationary core 44, and the fitting portion 43b and the press-fit portion 44c are fitted to the inner circumference of the filler ring 42 and the coil 41 is fitted into the case portion 44b, so that the coil 41 and the filler ring 42 are accommodated between the first stationary core 43 and the second stationary core 44 in a state of being constrained in the axial and radial directions.

[0072] 5, which is the tip of the press-fit portion 44c of the second stationary core 44, is provided with a tapered chamfered portion 44d, and an annular gap is formed between the filler ring 42 and the second stationary core 44. A seal ring 50 is accommodated in this annular gap. The seal ring 50 seals between the second stationary core 44 and the filler ring 42 by being in close contact with the flange 42a provided on the inner circumference of the filler ring 42 and the chamfered portion 44d of the press-fit portion 44c. Furthermore, a seal ring 51 that is in close contact with the outer circumference of the fitting portion 43b of the first stationary core 43 is installed in the annular groove 42b provided on the inner circumference of the right end of the filler ring 42 in FIG. 5. The seal ring 51 seals between the first stationary core 43 and the filler ring 42.

[0073] A first movable core 45 is slidably inserted on the inner periphery of the filler ring 42 between the fitting portion 43b of the first fixed core 43 and the press-fit portion 44c of the second fixed core 44.

[0074] 1, a connecting tube 44e that protrudes leftward and screws into the outer periphery of the socket 4d of the housing 4 of the damping valve 1 is provided.

[0075] The first movable core 45 is formed of a magnetic material and includes a sliding cylinder 45a that is in sliding contact with the inner circumference of the filler ring 42, an annular bottom portion 45b that protrudes from one end of the sliding cylinder 45a, that is, the right end in Fig. 5, toward the inner circumference and faces the left end face in Fig. 5 of the fitting portion 43b of the first fixed core 43, and an annular protrusion 45c that protrudes from the annular bottom portion 45b toward the first fixed core 43 and seats on and off the first fixed core 43. The inner diameter of the annular bottom portion 45b is enlarged on the right end side in Fig. 5, which is one end side, and a step portion 45d is formed on the inner circumference of the annular bottom portion 45b.

[0076] As described above, the outer periphery of the sliding contact tube 45a of the first movable core 45 is in sliding contact with the inner periphery of the filler ring 42, and the other end, which is the left end in Figure 5, is axially opposed to the right end in Figure 5 of the press-fit portion 44c of the second fixed core 44.

[0077] The annular protrusion 45c is provided on the outer periphery of the annular bottom 45b, and the outer diameter of the annular protrusion 45c is smaller than the diameter of the annular bottom 45b. Therefore, when the annular protrusion 45c abuts against the left end of the fitting portion 43b of the first fixed core 43 in FIG. 5, annular gaps are formed between the annular bottom 45b of the first movable core 45 and the fitting portion 43b of the first fixed core 43 on the inner and outer periphery of the annular protrusion 45c. The axial length of the annular protrusion 45c is from 0.13 mm to 0.15 mm, and the thickness of the annular gap between the inner and outer periphery of the annular protrusion 45c formed when the first movable core 45 abuts against the left end of the fitting portion 43b of the first fixed core 43 in FIG. 5 is in the range of from 0.13 mm to 0.15 mm.

[0078] 5, which is the other end of the sliding cylinder 45a of the first movable core 45, to the abutment surface of the annular protrusion 45c of the annular bottom portion 45b against the fitting portion 43b of the first fixed core 43, is shorter than the axial distance between the fitting portion 43b of the first fixed core 43 and the press-fit portion 44c of the second fixed core 44. Therefore, the first movable core 45 can be displaced in the axial direction while being guided in movement by the filler ring 42 between the first fixed core 43 and the second fixed core 44.

[0079] In addition, a tapered chamfered portion 45e is provided on the outer periphery of the other end of the sliding tube 45a so that the sliding tube 45a does not interfere with the flange 42a of the filler ring 42 when the first movable core 45 moves away from the first fixed core 43 toward the second fixed core.

[0080] Furthermore, a cylindrical spring bearing 52 made of a non-magnetic material is fitted to the inner circumference of the annular bottom portion 45b of the first movable core 45. The spring bearing 52 has a flange 52a on the outer circumference at the right end in FIG. 5, and an annular spring support portion 52b protruding inward from the inner circumference at the left end in FIG. 5. As described above, when the spring bearing 52 is fitted to the inner circumference of the annular bottom portion 45b, the flange 52a abuts against the step portion 45d formed on the inner circumference of the annular bottom portion 45b, and the relative movement of the spring bearing 52 to the other end side, that is, the left side in FIG. 5, with respect to the first movable core 45 is restricted. The spring bearing 52 may be attached to the first movable core 45 by press-fitting or may be screwed. Furthermore, the spring bearing 52 may be made of a magnetic material, but if it is made of a non-magnetic material, the magnetic flux can be concentrated in the sliding contact tube 45a where the first movable core 45 slides against the second movable core 46, and the attractive force applied to the first movable core 45 and the second movable core 46 of the solenoid 40 is not impaired. Note that, when the spring bearing 52 is made of a magnetic material, the spring bearing 52 and the first movable core 45 may be configured as a single inseparable part.

[0081] Furthermore, a spring 47 that constantly urges the first movable core 45 in the axial direction away from the first fixed core 43 is interposed in a compressed state between a spring support portion 52b provided on the inner periphery of the spring bearing 52 and the base 43a of the first fixed core 43. One end of the spring 47 is inserted into the inner periphery of the fitting portion 43b, and the other end side is inserted into the spring bearing 52, constantly urging the spring bearing 52 to constantly axially move away from the first fixed core 43. The inner diameter of the spring bearing 52 and the inner diameter of the fitting portion 43b are approximately the same diameter, and the spring 47 is prevented from being displaced radially by the spring bearing 52 and the fitting portion 43b.

[0082] In addition, the spring bearing 52 biased by the spring 47 is fitted to the inner periphery of the first movable core 45, and the flange 52a abuts against the step 45d on the inner periphery of the annular bottom 45b, so that the biasing force of the spring 47 is transmitted to the first movable core 45 via the spring bearing 52. Therefore, the first movable core 45 is constantly biased by the spring 47 in a direction away from the first fixed core 43 in the axial direction, that is, toward the second movable core 46 side.

[0083] The spring bearing 52 receives the biasing force of the spring 47 and the flange 52a and the step portion 45d of Since they are in contact with each other, they will not separate even if they are not press-fitted into the first movable core 45, but as described above, they may be press-fitted into the inner periphery of the first movable core 45.

[0084] The second movable core 46 is made of a magnetic material and has a cylindrical shape with a bottom, including a cylindrical portion 46a and a bottom portion 46b closing the left end of the cylindrical portion 46a in FIG. 5. The outer periphery of the cylindrical portion 46a is in sliding contact with the inner periphery of the sliding contact tube 45a of the first movable core 45. The inner diameter of the cylindrical portion 46a is larger than the outer diameter of the spring bearing 52 of the first movable core 45. Therefore, the second movable core 46 is guided in movement by the sliding contact tube 45a of the first movable core 45 with which the cylindrical portion 46a is in sliding contact, and can move in the axial direction relative to the first movable core 45. Since the outer periphery of the sliding contact tube 45a of the first movable core 45 is in sliding contact with the filler ring 42, both the first movable core 45 and the second movable core 46 can move in the axial direction without axial wobble with the filler ring 42. The outer periphery of the bottom portion 46b of the second movable core 46 is always in contact with the inner periphery of the press-fit portion 44c of the second fixed core 44.

[0085] In addition, since an annular gap is formed between the tubular portion 46a and the spring bearing 52, the space surrounded by the tubular portion 46a of the second movable core 46 and the sliding contact tube 45a and spring bearing 52 of the first movable core 45 is not sealed. In addition, a communication hole 46c that communicates between the inside and outside of the second movable core 46 is provided in the bottom portion 46b of the second movable core 46, so that the inside of the second movable core 46 that communicates with the inside of the spring bearing 52 is also not sealed.

[0086] Therefore, the second movable core 46 can move smoothly in the axial direction relative to the first movable core 45 , and the first movable core 45 can also move smoothly in the axial direction relative to the filler ring 42 and the second movable core 46 .

[0087] Furthermore, the spring 47 biases the first movable core 45 toward the second fixed core. When the first movable core 45 and the second movable core 46 approach each other in the axial direction and are compressed, the disc spring 48 exerts a resilient force to restrict the first movable core 45 and the second fixed core 44 from approaching each other any further. When the second movable core 46 approaches the second fixed core 44 in the axial direction and is compressed, the disc spring 49 exerts a resilient force to restrict the second movable core 46 from approaching each other any further toward the second fixed core 44. Note that, instead of the disc springs 48 and 49, an elastic body such as a wave washer or rubber may be provided, or a member other than an elastic body may be provided as long as it can restrict the approach between the first movable core 45 and the second movable core 46 and the approach between the second movable core 46 and the second fixed core 44.

[0088] As described above, the first fixed core 43, the second fixed core 44, the first movable core 45 and the second movable core 46 are each made of a magnetic material, and form a magnetic path P in the solenoid 40, as shown in Fig. 5. In other words, the magnetic path P passes through the sliding portion between the sliding contact cylinder 45a of the first movable core 45 and the cylindrical portion 46a of the second movable core 46.

[0089] When a current is applied to the coil 41, a magnetic field generated in the coil 41 passes through the first fixed core 43, the second fixed core 44, the first movable core 45, and the second movable core 46 and returns to the coil 41. Therefore, when a current is applied to the coil 41, the first movable core 45 is attracted to the first fixed core 43 disposed on the right side in Fig. 5, and the second movable core 46 is attracted to the second fixed core 44 disposed on the left side in Fig. 5. In other words, when a current is applied to the coil 41 in the solenoid 40, the first movable core 45 and the second movable core 46 are attracted in directions away from each other in the axial direction.

[0090] The solenoid 40 configured in this manner is assembled to the damping valve 1 by screwing the housing 4 onto the second fixed core 44, and then a screw portion (not shown) provided on the outer periphery of the left end of the second fixed core 44 in FIG. 5 is screwed into a nut 120 attached to a sleeve 109a of an outer cylinder 109 of the shock absorber 100, thereby attaching the solenoid 40 to the shock absorber 100. When the second fixed core 44 is attached in this manner, all of the components of the solenoid 40 are housed within the second fixed core 44, so the solenoid 40 can be attached to the shock absorber 100.

[0091] When the solenoid 40 is attached to the shock absorber 100 in this manner, the bottom 46b of the second movable core 46 comes into contact with the plunger 34 attached to the rear end of the valve body 22 of the solenoid valve 24. Thus, the thrust generated by the solenoid 40 is transmitted to the valve body 22 via the plunger 34. The valve body 22 is biased in the valve opening direction by the coil spring 33, while receiving the thrust of the solenoid 40 in the valve closing direction. Therefore, by adjusting the thrust of the solenoid 40, the pressure at which the valve body 22 separates from the valve seat member 21 due to the pressure received from the pilot passage 23, that is, the valve opening pressure of the solenoid valve 24, can be adjusted. The pressure upstream of the solenoid valve 24 in the pilot passage 23 and downstream of the orifice 10d becomes equal to the valve opening pressure of the solenoid valve 24, so that the pressure in the back pressure chamber 5 also becomes equal to the valve opening pressure of the solenoid valve 24. Thus, by adjusting the thrust of the solenoid 40, the pressure in the back pressure chamber 5 can be controlled.

[0092] Next, Fig. 6 shows the relationship between the amount of current supplied to the solenoid 40 and the force that the solenoid 40 exerts on the valve body 22 of the solenoid valve 24. In Fig. 6, the amount of current Ia is the minimum amount of current required to attract the first movable core 45, which is separated from the first fixed core 43, to the first fixed core 43, and the amount of current Ib is the minimum amount of current required to maintain the attracted state between the first fixed core 43 and the first movable core 45 after the first movable core 45 is attracted to the first fixed core 43. The amount of current Ic will be described later. Each figure showing the solenoid 40 shows a state in which the first movable core 45 is attracted to the first fixed core 43 by supplying current to the coil 41.

[0093] First, when the amount of current supplied to the coil 41 is zero, that is, when the solenoid 40 is not energized, the first movable core 45 is pushed leftward in FIG. 5 by the biasing force of the spring 47 and hits the second movable core 46 via the disc spring 48, and the second movable core 46 is pushed leftward together with the valve body 22. In this way, when the solenoid 40 is not energized, the valve body 22 receives a leftward force from the spring 47 via the second movable core 46, the disc spring 48, and the first movable core 45. In other words, when the solenoid 40 is not energized, the solenoid 40 applies a leftward force caused by the biasing force of the spring 47 to the valve body 22.

[0094] Next, when the amount of current supplied to the solenoid 40 is increased, the force to the right in FIG. 5 attracting the first movable core 45 to the first fixed core 43 increases, and the force to the left in FIG. 5 attracting the second movable core 46 to the second fixed core 44 also increases. In such a case, in a region where the amount of current supplied to the solenoid 40 is less than the current amount Ia, the biasing force of the spring 47 is transmitted to the valve body 22, but the first movable core 45 left A part of the force of the spring 47 biasing the first movable core 45 in the direction right Therefore, in a region where the amount of current is less than the current amount Ia, the leftward force that the solenoid 40 applies to the valve body 22 decreases as the amount of current supplied to the solenoid 40 increases.

[0095] On the other hand, when the amount of current supplied to the solenoid 40 is increased and the amount of current is equal to or greater than the amount of current Ia, the first movable core 45 is attracted and attracted to the first fixed core 43 against the biasing force of the spring 47. In this state, the biasing force of the spring 47 is not transmitted to the second movable core 46, and only the force attracting the second movable core 46 to the second fixed core 44 acts in a direction to press down the valve body 22. This force in the leftward direction in FIG. 5 attracting the second movable core 46 increases in proportion to the amount of current supplied to the solenoid 40, so that in a region in which the amount of current supplied to the solenoid 40 is equal to or greater than the amount of current Ia, the more the amount of current supplied to the solenoid 40 is increased, the more the leftward force that the solenoid 40 applies to the valve body 22 increases in proportion to the amount of current.

[0096] On the other hand, when the amount of current supplied to the solenoid 40 is reduced from a state in which the first movable core 45 is attracted to the first fixed core 43 and the biasing force of the spring 47 is not transmitted to the second movable core 46, the force in the right direction in FIG. 5 attracting the first movable core 45 to the first fixed core 43 decreases, and the force in the left direction in FIG. 5 attracting the second movable core 46 to the second fixed core 44 also decreases. Even in such a case, in a region in which the amount of current supplied to the solenoid 40 is equal to or greater than the current amount Ib, the state in which the first movable core 45 is attracted to the first fixed core 43 and the biasing force of the spring 47 is not transmitted to the second movable core 46 is maintained. For this reason, in a region in which the amount of current supplied to the solenoid 40 is equal to or greater than the current amount Ib, the more the amount of current supplied to the solenoid 40 is reduced, the more the leftward force applied by the solenoid 40 to the valve body 22 decreases in proportion to the amount of current.

[0097] On the other hand, when the amount of current supplied to the solenoid 40 is reduced from a state in which the first movable core 45 is attracted to the first fixed core 43 and the biasing force of the spring 47 is not transmitted to the second movable core 46, and the amount of current reaches a region less than the current amount Ib, the attracted state between the first movable core 45 and the first fixed core 43 is released by the biasing force of the spring 47, and the biasing force of the spring 47 is transmitted to the second movable core 46. For this reason, in a region in which the amount of current is less than the current amount Ib, the more the amount of current supplied to the solenoid 40 is reduced, the more the force in the leftward direction in FIG. 5 that the solenoid 40 applies to the valve body 22 increases.

[0098] As can be seen from Fig. 6, Ib, which is the minimum amount of current required to maintain adhesion between the first movable core 45 and the first fixed core 43, is smaller than Ia, which is the minimum amount of current required to attract the separated first movable core 45 to the first fixed core 43 (Ia>Ib). Therefore, the characteristic of the force that the solenoid 40 applies to the valve body 22 relative to the amount of current supplied to the solenoid 40 has hysteresis. Note that in Fig. 6, the region where the amount of current supplied to the solenoid 40 is small is exaggerated for ease of understanding.

[0099] In this embodiment, when controlling the amount of current supplied to the solenoid 40 to control the force that the solenoid 40 applies to the valve body 22, a current of Ia or more is once supplied to attract the first movable core 45 to the first fixed core 43, and then the amount of current supplied to the solenoid 40 is controlled within a range of Ic or more, which is greater than the current Ib. Once the first movable core 45 is attracted to the first fixed core 43, the first movable core 45 will not separate from the first fixed core 43 unless the amount of current supplied to the solenoid 40 becomes less than Ib, so the current Ic may be smaller than the current Ia as long as it is greater than the current Ib. As a result, during normal operation when the amount of current flowing through the solenoid 40 is controlled, the first movable core 45 is maintained in a state where it is attracted to the first fixed core 43, so that the amount of current supplied to the solenoid 40 and the force acting on the valve body 22 in the leftward direction in Figure 5 are proportional to each other, and this force increases as the amount of current supplied to the solenoid 40 increases.

[0100] In the normal state (when under control), the force that the solenoid 40 exerts on the valve body 22 due to the magnetic force generated by energizing the solenoid 40 is referred to as the "thrust" of the solenoid 40. In other words, the thrust of the solenoid 40 is controlled by controlling the amount of current supplied to the solenoid 40. In this embodiment, the amount of current supplied to the solenoid 40 and the thrust that the solenoid 40 exerts on the valve body 22 are proportional to each other, so that the thrust increases as the amount of current supplied is increased, and decreases as the amount of current supplied is decreased.

[0101] On the other hand, in a fail state where the solenoid 40 is de-energized, the valve body 22 is biased leftward in FIG. 5 by the spring 47 of the solenoid 40, and the biasing force is determined in advance according to the specifications of the spring 47, such as the spring constant. The direction of the biasing force of the spring 47 that biases the valve body 22 in a fail state (de-energized) is the same as the direction of the thrust applied to the valve body 22 in a normal state. The biasing force of the spring 47 in a state where the solenoid 40 is de-energized is set to be larger than the biasing force of the coil spring 33 that separates the valve body 22 from the valve seat member 21. Therefore, the solenoid 40 can exert a thrust that seats the valve body 22 on the valve seat member 21 against the coil spring 33 even when de-energized.

[0102] In this way, the thrust of the solenoid 40 is controlled so that the amount of current supplied to the coil 41 of the solenoid 40 is equal to or greater than the current amount Ic under normal conditions, and the greater the amount of current supplied, the greater the thrust. In other words, when the amount of current supplied to the solenoid 40 increases, the thrust of the solenoid 40 that pushes the valve body 22 in the valve closing direction against the coil spring 33 increases, and the valve opening pressure of the solenoid valve 24 increases. Therefore, when the amount of current supplied to the solenoid 40 is set to the current amount Ic under normal conditions, the valve opening pressure of the solenoid valve 24 becomes minimum, the pressure in the back pressure chamber 5 becomes minimum, and the valve opening pressure of the leaf valve 3 becomes minimum. On the other hand, when the amount of current supplied to the solenoid 40 is maximized, the valve opening pressure of the solenoid valve 24 becomes maximum, the pressure in the back pressure chamber 5 becomes maximum, and the valve opening pressure of the leaf valve 3 becomes maximum. The maximum amount of current supplied to the solenoid 40 is appropriately determined depending on the specifications of the coil 41 and the power source.

[0103] Furthermore, in the event of a failure, as described above, the solenoid 40 transmits the biasing force of the spring 47 to the valve body 22 to apply a thrust force opposing the coil spring 33. Therefore, in the event of a failure, the valve body 22 is pressed against the valve seat member 21 by a force obtained by subtracting the biasing force of the coil spring 33 from the biasing force of the spring 47, and the valve opening pressure of the solenoid valve 24 is determined according to the specifications of the spring constants of the spring 47 and the coil spring 33, etc. Therefore, even in the event of a failure, the valve opening pressure of the solenoid valve 24 can be preset, and the pressure in the back pressure chamber 5 can be set to the preset valve opening pressure, so that the valve opening pressure of the leaf valve 3 can be set arbitrarily.

[0104] Here, the solenoid 40 of the present embodiment includes a coil 41, a first fixed core 43 arranged at one axial end of the coil 41, a second fixed core 44 arranged at the other axial end of the coil 41 with a gap between it and the first fixed core 43, a cylindrical first movable core 45 arranged between the first fixed core 43 and the second fixed core 44 and attracted to the first fixed core 43 when current is passed through the coil 41, a cylindrical second movable core 46 with a bottom, inserted slidably into the first movable core 45, arranged between the first fixed core 43 and the second fixed core 44 with a bottom 46b facing the second fixed core 44, and attracted to the second fixed core 44 when current is passed through the coil 41, and a spring 47 interposed between the first movable core 45 and the first fixed core 43 for urging the first movable core 45 toward the second fixed core 44.

[0105] In the solenoid 40 of this embodiment configured as described above, the second movable core 46 is inserted so as to be freely slidable within the first movable core 45, and the magnetic path P passes through the sliding contact portion between the sliding tube 45a of the first movable core 45 and the tubular portion 46a of the second movable core 46, and the sliding contact portion between the press-fit portion 44c of the second fixed core 44 and the outer periphery of the left end of the tubular portion 46a of the second movable core 46 in Figure 5.

[0106] In the solenoid 40 of this embodiment, the second fixed core 44 and the filler ring 42 are not joined by brazing, but the filler ring 42 is fixed to the second fixed core 44 by pressing it into the outer periphery of an annular press-fit portion 44c that protrudes from the base 44a of the second fixed core 44 toward the first fixed core.

[0107] Since the first movable core 45 is disposed on the outer periphery, instead of the second movable core 46 which is in sliding contact with the inner periphery of the press-fit portion 44c, it is not necessary to provide an annular recess into which the press-fit portion 44c enters and exits, as shown in Fig. 8, on the outer periphery of the bottom portion 46b at the left end in Fig. 5 of the second movable core 46. Therefore, even if the thickness of the bottom portion 46b of the second movable core 46 is not increased, the thickness from the tubular portion 46a to the bottom portion 46b is not reduced, and the magnetic path cross-sectional area in the second movable core 46 can be secured, and magnetic flux saturation in the second movable core 46 can be suppressed. In other words, magnetic flux saturation in the second movable core 46 can be suppressed without increasing the axial length of the bottom portion 46b of the second movable core 46.

[0108] By adopting a structure in which the second movable core 46 is slidably inserted into the first movable core 45 in this manner, the filler ring 42 can be joined to the second fixed core 44 without increasing the axial length of the second movable core 46. To An inexpensive press fit can be adopted. Even without increasing the axial length of the solenoid 40, when the second movable core 46 and the first movable core 45 are at their farthest apart positions, that is, when the second movable core 46 is closest to the second fixed core 44 in the axial direction and the first movable core 45 is in contact with the fitting portion 43b of the first fixed core 43, the length of the contact portion (lap length) between the tubular portion 46a of the second movable core 46 and the sliding contact tubular portion 45a of the first movable core 45 can be sufficiently secured.

[0109] That is, even if the total length of the second movable core 46 is made the same as that of a conventional solenoid, there is no need to increase the axial length, which is the thickness of the bottom portion 46b of the second movable core 46, so the length of the tube portion 46a can be secured to be the same as that of a conventional solenoid. If the length of the sliding contact tube 45a of the first movable core 45 is also made the same as that of a conventional solenoid, the lap length can be secured to be the same as that of a conventional solenoid. Therefore, even if the total length of the solenoid 40 is made the same as that of a conventional solenoid, the lap length when the first movable core 45 and the second movable core 46 are most separated does not decrease, and the suction force applied by the solenoid 40 to the first movable core 45 and the second movable core 46 does not decrease. Therefore, even if an inexpensive structure is adopted for the solenoid 40, the total length of the solenoid 40 does not increase, and the solenoid 40 can generate sufficient thrust.

[0110] Furthermore, the solenoid 40 of the present embodiment includes a cylindrical filler ring 42 disposed on the inner periphery of the coil 41 and interposed between the first fixed core 43 and the second fixed core 44, the first movable core 45 is slidably inserted into the inner periphery of the filler ring 42, and the second fixed core 44 is annular and has a press-fit portion 44c press-fitted into the filler ring 42 and into which the second movable core 46 is slidably inserted. According to the solenoid 40 configured in this manner, the filler ring 42 can guide the axial movement of the first movable core 45 and the second movable core 46, and the filler ring 42 and the second fixed core 44 can be integrated at low cost by press-fitting the press-fit portion 44c into the filler ring 42.

[0111] In the solenoid 40 of the present embodiment, the first movable core 45 has a sliding cylinder 45a that is in sliding contact with the outer periphery of the second movable core 46, and an annular bottom portion 45b that protrudes from one end of the sliding cylinder 45a toward the inner periphery, and the annular bottom portion 45b is provided with an annular protrusion 45c that protrudes toward the first fixed core 43 and is seated on and removed from the first fixed core 43. In the solenoid 40 configured in this manner, when the first movable core 45 is attracted to the first fixed core 43, only the annular protrusion 45c abuts against the first fixed core 43. Therefore, even if contaminants such as cutting chips get between the first movable core 45 and the first fixed core 43, the contaminants escape to the inner or outer periphery of the annular convex portion 45c between the first movable core 45 and the first fixed core 43 when the annular convex portion 45c approaches and seats on the first fixed core 43, so that it is possible to prevent the contaminants from getting caught between the annular convex portion 45c and the first fixed core 43. Therefore, even if contaminants are present between the first movable core 45 and the first fixed core 43, the annular convex portion 45c of the first movable core 45 can be attracted to the first fixed core 43 and brought into close contact with it, and by constantly supplying the current Ib to the coil 41, the first movable core 45 can be maintained in a state of being attracted to the first fixed core 43, and the operation of the solenoid 40 becomes stable.

[0112] The axial length of the annular protrusion 45c is set to a range of 0.13 mm to 0.15 mm, so that when the annular protrusion 45c abuts against the fitting portion 43b of the first fixed core 43, the magnetic flux from the first movable core 45 to the first fixed core 43 can pass not only through the annular protrusion 45c but also through the gaps formed on the inner and outer peripheries of the annular protrusion 45c. P This can form a part of the magnetic flux path, which can increase the force of attraction between the first movable core 45 and the first fixed core 43, and can effectively reduce the risk of contamination by narrowing the radial width of the annular protrusion 45c as much as possible. P When not used as a suction hole, the cross-sectional area of ​​the annular protrusion 45c cut by a plane perpendicular to the axial direction may be set so as to ensure a sufficient suction force.

[0113] In addition, the annular protrusion 45c of the first movable core 45 is provided on the outer periphery of the annular bottom 45b, and the outer diameter of the annular protrusion 45c is smaller than the diameter of the annular bottom 45b, so that when it abuts against the fitting portion 43b of the first fixed core 43, it is seated at a position radially spaced from the outer periphery of the fitting portion 43b. The outer periphery of the fitting portion 43b of the first fixed core 43 may not be flat but may have a partially raised shape due to the influence of the processing of the first fixed core 43 or contact with other parts, but when the annular protrusion 45c is configured as described above, it abuts against the fitting portion 43b while avoiding the outer periphery of the fitting portion 43b, which may not be flat, so that the entire annular protrusion 45c can be in close contact with the fitting portion 43b. In addition, when the annular protrusion 45c is arranged on the outer periphery of the annular bottom 45b, Cage When the annular protrusion 45c abuts against the fitting portion 43b of the first fixed core 43, the sealed space generated on the outer circumferential side of the annular protrusion 45c becomes smaller, so that the first movable core 45 can move smoothly toward the first fixed core 43. Note that the space on the inner circumferential side of the annular protrusion 45c when it abuts against the fitting portion 43b of the first fixed core 43 is connected to the outside of the solenoid 40 via the inside of the spring bearing 52 and the communication hole 46c of the second movable core 46, so the movement of the first movable core 45 is not impeded.

[0114] Furthermore, in the solenoid 40 of the present embodiment, the filler ring 42 has a flange 42a on its inner periphery that faces the press-fit portion 44c in the axial direction, and a seal ring 42 is interposed between the flange 42a and the press-fit portion 44c to seal between the filler ring 42 and the second fixed core 44. 50 In the solenoid 40 thus configured, a seal ring is provided between the flange 42a of the filler ring 42 and the press-fit portion 44c of the second fixed core 44. 50 Since the press-fit portion 44c is provided with an annular groove on the outer periphery thereof and a seal ring is attached to the annular groove, the overall length of the press-fit portion 44c can be made shorter than in the case of adopting a structure in which the press-fit portion 44c is provided with an annular groove and a seal ring is attached to the annular groove. Therefore, since the press-fit portion 44c can be made shorter, the overall length of the solenoid 40 of this embodiment can be made shorter.

[0115] Next, a description will be given below of the operation of the damping valve 1 according to this embodiment and the shock absorber 100 equipped with the damping valve 1. When the shock absorber 100 expands or contracts and hydraulic oil is discharged from the extension-side chamber 104 to the reservoir 108 via the damping valve 1, if the damping valve 1 operates normally, the pressure upstream of the passage 10e and the pilot passage 23 increases, and when a current is supplied to the solenoid 40 to adjust the valve opening pressure of the solenoid valve 24, the pressure between the orifice 10d in the pilot passage 23 and the solenoid valve 24 is led to the back pressure chamber 5.

[0116] The internal pressure of the back pressure chamber 5 is controlled by the valve opening pressure of the solenoid valve 24, and by adjusting this valve opening pressure with the solenoid 40, the pressure acting on the back surface of the leaf valve 3 can be adjusted, and thus the valve opening pressure at which the leaf valve 3 opens the passage 10e can be controlled.

[0117] More specifically, the pressure in the intermediate chamber 9 increases due to the pressure in the expansion-side chamber 104, and the force that bends the outer periphery of the leaf valve 3 to the right in FIG. 3 is generated by the internal pressure of the back pressure chamber 5 and the leaf spring 7. AttachedWhen the force is overcome, the leaf valve 3 is bent and lifted off the valve seat 2b, forming a gap between the leaf valve 3 and the disk 2, and the passage 10e is opened. Therefore, by adjusting the pressure in the back pressure chamber 5 by the solenoid valve 24, the pressure in the intermediate chamber 9 that can lift the leaf valve 3 off the valve seat 2b can be adjusted. In other words, the opening pressure of the leaf valve 3 can be controlled by the amount of current given to the solenoid 40. Therefore, as shown in FIG. 7, the damping force characteristic (damping force characteristic with respect to piston speed) of the shock absorber 100 has a large damping coefficient (line X in FIG. 7) until the leaf valve 3 opens, because the hydraulic oil passes through the sliding gap and the notched orifice 2d of the damping valve 1. However, when the leaf valve 3 lifts off the valve seat 2b and opens the passage 10e, the slope becomes smaller as shown by line Y in FIG. 7, that is, the damping coefficient becomes smaller.

[0118] As described above, since the pressure boost ratio at the leaf valve 3 is smaller than the pressure boost ratio at the disk 2, the opening pressure of the leaf valve 3 is smaller than the opening pressure of the disk 2, and therefore the disk 2 remains seated on the base 10a unless the pressure difference generated by the port 2a reaches the opening pressure that lifts the disk 2 off the base 10a. On the other hand, when the leaf valve 3 is bent and in an open state, the piston speed of the shock absorber 100 increases, and the pressure difference generated by the port 2a reaches the opening pressure that lifts the disk 2 off the base 10a, the disk 2 also lifts off the base 10a to open the passage 10e. In this case, when only leaf valve 3 is open and passage 10e is connected to reservoir 108 only via port 2a, if disc 2 leaves base 10a, passage 10e is connected directly to reservoir 108 not via port 2a, and the flow path area becomes larger. As a result, the damping force characteristics of shock absorber 100 will have a smaller slope than when only leaf valve 3 is open, as shown by center line Z in Figure 7, i.e., the damping coefficient will be even smaller.

[0119] By adjusting the amount of electricity supplied to the solenoid 40 to increase or decrease the opening pressure of the solenoid valve 24, the damping force characteristics of the shock absorber 100 can be changed so as to move lines Y and Z up and down within the range shown by the dashed lines in Figure 7.

[0120] In addition, the pressure boost ratio at the leaf valve 3 can be made smaller than the pressure boost ratio at the disk 2, so that the valve opening pressure of the leaf valve 3 becomes smaller than the valve opening pressure of the disk 2 and relieves the passage 10e in two stages. Therefore, in this damping valve 1, the damping force at the time of full soft, when the valve opening pressure of the solenoid valve 24 is minimized, can be reduced and the variable range of the damping force can be increased.

[0121] Therefore, according to the damping valve 1 of this embodiment, when the piston speed of the shock absorber 100 is in the low speed range, a soft damping force can be outputted, so that the damping force does not become excessive, and when the piston speed becomes in the high speed range, the upper limit of the hard damping force required can be raised, so that the damping force does not become insufficient. Therefore, if this damping valve 1 is applied to the shock absorber 100, the damping force variable range can be made large, and the ride comfort of the vehicle can be improved.

[0122] In the present embodiment, the solenoid valve 24 includes a valve seat member 21 having a small diameter cylindrical portion 21a having a through hole 21d communicating between the inside and outside, and an annular valve seat 21f provided at the end of the small diameter cylindrical portion 21a, and a valve body 22 having a small diameter portion 22a slidably inserted into the small diameter cylindrical portion 21a, a large diameter portion 22b, and a recess 22c provided between the small diameter portion 22a and the large diameter portion 22b and facing the through hole 21d, and the end of the large diameter portion 22b of the valve body 22 is seated on and separated from the valve seat 21f. Thus, the solenoid valve 24 can reduce the pressure receiving area where pressure acts in the direction of the valve body 22 coming out of the valve seat member 21, and can increase the flow path area when the valve is open while reducing the pressure receiving area. In this way, the pressure-receiving area of ​​the valve body 22 can be reduced, thereby reducing the thrust that the solenoid 40 must output, and by increasing the flow path area when the valve is open, the amount of movement of the valve body 22 can be reduced, thereby reducing overshoot, in which the solenoid valve 24 opens excessively.

[0123] In addition, in the event of a failure, the current supply to the solenoid 40 is cut off, but the solenoid 40 includes a first movable iron core 45 and a second movable iron core 46, and even when not energized, the solenoid 40 can apply a thrust to the valve body 22 in the same direction as when energized by the spring 47. Therefore, according to the damping valve 1 of this embodiment, even in the event of a failure, the solenoid 40 can exert a thrust and the valve opening pressure of the leaf valve 3 can be set to a value that is arbitrarily set in advance, so that the shock absorber 100 can exert a sufficient damping force.

[0124] In addition, in a typical pull-type solenoid that cannot apply thrust to the valve body 22 in the event of a failure, the pressure in the back pressure chamber 5 becomes very low, and the valve opening pressure of the leaf valve 3 also becomes very low, resulting in insufficient damping force of the shock absorber. Therefore, when such a solenoid is used, a separate fail valve is required to increase the pressure in the back pressure chamber 5 in the event of a failure, which complicates the structure of the damping valve. In contrast, the damping valve 1 of this embodiment can cause the shock absorber 100 to exert a preset damping force in the event of a failure without the need to install a separate fail valve.

[0125] Furthermore, in a typical push-type solenoid that applies maximum thrust to the valve body 22 in the event of a failure, the pressure in the back pressure chamber 5 becomes maximum, and the valve opening pressure of the leaf valve 3 becomes maximum, resulting in excessive damping force of the shock absorber. Therefore, even when such a solenoid is used, a separate fail valve is required to adjust the pressure in the back pressure chamber 5 to an appropriate level in the event of a failure, making the structure of the damping valve complicated. In contrast, the damping valve 1 of this embodiment can cause the shock absorber 100 to exert a preset damping force in the event of a failure without the need to install a separate fail valve.

[0126] The damping valve 1 and the shock absorber 100 operate as described above. The solenoid valve 24 of this embodiment includes the valve body 22 that opens and closes the pilot passage (passage) 23, and the solenoid 40 applies a force that attracts the second movable iron core 46 toward the second fixed iron core 44 when the coil 41 is energized to the valve body 22 in the direction of closing the pilot passage (passage) 23, so that the valve opening pressure of the valve body 22 can be adjusted in the normal state, and the valve opening pressure of the valve body 22 in the event of a failure can be set by the biasing force of the spring 47. With the solenoid valve configured in this manner, the valve opening pressure of the valve body can be adjusted by using a low-cost, small-sized solenoid, and the valve opening pressure of the valve body in the event of a failure can be set by the biasing force of the spring. Furthermore, as described above, in the solenoid 40 of this embodiment, the greater the amount of current supplied, the greater the thrust applied to the object. Therefore, in the solenoid valve 24, the greater the amount of current supplied to the solenoid 40, the greater the thrust that the solenoid 40 applies to the valve body 22 in the closing direction, and the higher the valve opening pressure of the solenoid valve 24.

[0127] The damping valve 1 of this embodiment also includes a disk 2 having a port 2a and a valve seat 2b surrounding the port 2a, a leaf valve 3 whose front side is seated on and off the valve seat 2b to open and close the port 2a, a cylindrical housing 4 provided on the back side of the leaf valve 3, an annular spool 6 that abuts against the back side of the leaf valve 3 and is inserted slidably into the inner periphery of the housing 4 to form, together with the housing 4, a back pressure chamber 5 that applies back pressure inwardly to the leaf valve 3, an annular spring support part 4g that is on the back side of the leaf valve 3 and faces the back pressure chamber 5 and has an outer diameter smaller than the inner diameter of the spool 6, and an annular leaf spring 7 that is interposed between one end of the spool 6 that is the end opposite to the leaf valve and the spring support part 4g to urge the spool 6 in a direction to abut against the leaf valve 3.

[0128] In the damping valve 1 configured in this manner, the spool 6 is disposed on the inner periphery of the housing 4, the inner and outer diameters of the spool 6 can be reduced, and the leaf spring 7 that biases the spool 6 is supported by the end of the spool 6 on the side opposite to the leaf valve, eliminating the need to provide a spring bearing for supporting the leaf spring 7 on the inner periphery of the spool 6. Therefore, according to the damping valve 1 of this embodiment, the volume of the spool 6 can be reduced to reduce the inertial mass of the spool 6, and therefore the effect of the inertia of the spool 6 when the leaf valve 3 is opened or closed is reduced, thereby improving the responsiveness of the opening and closing operation of the leaf valve 3.

[0129] In the damping valve 1 of this embodiment, the spring support portion 4g faces the back surface of the leaf valve 3 and abuts only against the anti-leaf valve side of the inner circumferential end of the leaf spring 7. In the damping valve 1 configured in this manner, only the inner periphery of the anti-leaf valve side of the leaf spring 7 abuts against the spring support portion 4g facing the back surface of the leaf valve 3, and therefore the inner periphery of the leaf spring 7 is not fixedly supported by the housing 4. This reduces the overall deflection amount of the leaf spring 7 relative to the amount of movement of the spool 6, and therefore reduces the apparent spring constant of the leaf spring 7. Here, if it is desired to further reduce the inertial mass of the spool 6, the inner and outer diameters of the spool 6 will be reduced, but this will reduce the difference between the inner and outer diameters of the leaf spring 7 and increase the spring constant, which is a contradiction that causes the valve opening pressure of the leaf valve 3 to vary from product to product. However, in the damping valve 1 of this embodiment, the apparent spring constant of the leaf spring 7 can be reduced and the effect of the leaf spring 7 on the valve opening pressure of the leaf valve 3 can be reduced, thereby preventing variations in the damping force even if the inner and outer diameters of the spool 6 are made smaller to reduce the inertial mass. In other words, according to the damping valve 1 configured in this manner, the inertial mass of the spool 6 can be further reduced and the responsiveness in the opening and closing operation of the leaf valve 3 can be further improved.

[0130] Furthermore, the damping valve 1 of this embodiment is configured such that the spool 6 has a tapered portion 6b on the inside of the one end outer periphery 6a, which is the outer periphery of one end, and the leaf spring 7 abuts against the spool 6 only at the one end outer periphery 6a. In the damping valve 1 configured in this manner, the support diameter on the outer periphery side of the leaf spring 7 can be increased, and the amount of deflection of the leaf spring 7 can be reduced. Therefore, by providing the tapered portion 6b on the inside of the one end outer periphery 6a of the spool 6 in this manner, the apparent spring constant of the leaf spring 7 can be reduced. Therefore, according to the damping valve 1 configured in this manner, the inertial mass of the spool 6 can be further reduced, and the responsiveness in the opening and closing operation of the leaf valve 3 can be further improved, similarly to the above-mentioned case where the inner periphery of the leaf spring 7 is not fixedly supported.

[0131] In addition, the damping valve 1 of this embodiment is configured such that the spool 6 has a tapered portion 6d on the inside of the other end outer periphery 6c, which is the outer periphery at the other end of the spool 6 that is the leaf valve side end, and the leaf valve 3 abuts only against the other end outer periphery 6c of the spool 6. According to the damping valve 1 configured in this manner, the leaf valve 3 is prevented from escaping by the tapered portion 6d of the spool 6. Gas space but Since the spool 6 is formed in this manner, it does not interfere with the leaf valve 3, and therefore the number of annular plates in the leaf valve 3 and the size of the outer diameter can be freely selected.

[0132] The damping valve 1 of this embodiment also includes a pilot passage 23 that communicates the inside of the back pressure chamber 5 with the upstream side of the port 2a, and a solenoid valve 24 that controls the pressure in the back pressure chamber 5. With the damping valve 1 configured in this manner, the pressure in the back pressure chamber 5 is adjusted by the solenoid valve 24 to change the valve opening pressure of the leaf valve 3, thereby adjusting the damping force of the shock absorber 100. In this embodiment, the orifice 10d is provided in the pilot passage 23 to reduce the pressure in the passage 10e and introduce it into the back pressure chamber 5, but instead of the orifice, another valve such as a choke may be used to reduce the pressure.

[0133] In the case of the damping valve 1 of this embodiment, the pressure in the back pressure chamber 5 is controlled by the solenoid 40 to control the valve opening pressure of the disk 2 and the leaf valve 3. However, the solenoid 40 does not control the valve opening pressure of the solenoid valve 24, and the solenoid valve 24 is a passive pressure. control Even without controlling the pressure in the back pressure chamber 5 as a valve, the pressure boost ratio in the leaf valve 3 can be made smaller than the pressure boost ratio in the disc 2, so that the damping characteristics can be changed in two stages. When the piston speed is in the low speed range, a small damping force can be output, preventing excessive damping force, and when the piston speed reaches the high speed range, a large damping force can be output, eliminating insufficient damping force.

[0134] Furthermore, since the disk 2 is stacked in a floating state relative to the valve holding member 10, the passage 10e can be opened widely, and the damping coefficient when the disk 2 is open can be reduced, making it extremely easy to control the damping force by the solenoid 40. Also, since the leaf valve 3 is an annular leaf valve whose inner periphery is fixed to the valve holding member 10 and whose outer periphery is seated on and removed from the valve seat 2b, even if the disk 2 is provided to change the damping force in two stages, the leaf valve 3 can be used to move the disk 2. Attached Since the disk 2 is helped to return to a seated position on the base 10a after the disk 2 opens the passage 10e due to the force applied, there is no delay in closing the passage 10e when the expansion / contraction direction of the shock absorber 100 is switched, and the response of the damping force generation is not impaired.

[0135] Moreover, the shock absorber 100 of this embodiment includes a cylinder 101, a rod 103 inserted into the cylinder 101 so as to be axially movably, a disk 2 having a port 2a through which liquid flows when the cylinder 101 and the rod 103 move relative to each other in the axial direction and a valve seat 2b surrounding the port 2a, a leaf valve 3 which seats on and off the valve seat 2b to open and close the port 2a, a pilot passage 23 having an orifice (restriction) 10d provided therein and which reduces and directs the pressure upstream of the port 2a to the back surface of the leaf valve 3, a solenoid valve 24 which controls the pressure at the back surface of the leaf valve 3, and a solenoid 40 which provides the solenoid valve 24 with a thrust force which is generated when current is applied to the coil 41 and which attracts the second movable core 46 toward the second fixed core 44.

[0136] In this way, if the leaf valve 3 provides resistance to the flow of liquid passing through the port 2a when the cylinder 101 and the rod 103 move relative to each other in the axial direction, the shock absorber 100 can generate a damping force due to the resistance. Also, since the back pressure of the leaf valve 3 can be adjusted by the solenoid valve 24, the magnitude of the damping force generated can be adjusted by changing the amount of current supplied to the solenoid 40, and the back pressure of the leaf valve 3 can be set by setting the biasing force of the spring 47 of the solenoid 40 in the event of a failure, thereby optimizing the damping force generated by the shock absorber 100 in the event of a failure. Therefore, according to the shock absorber 100 configured in this way, the back pressure of the leaf valve 3 can be adjusted by the solenoid valve 24 that utilizes a low-cost, small-sized solenoid, so that the damping force can be adjusted at low cost and without increasing in size.

[0137] Furthermore, as described above, in the solenoid valve 24, the valve opening pressure of the solenoid valve 24 can be increased as the amount of current supplied to the solenoid 40 increases. Leaf Valve 3This increases the back pressure in the solenoid 40, and increases the damping force that is generated. In other words, in the shock absorber 100 configured in this manner, the damping force that is generated when the amount of current supplied to the solenoid 40 is small can be reduced, so that when the shock absorber 100 is used in the suspension of a vehicle, power consumption during normal driving can be reduced. This also makes it possible to suppress heat generation in the solenoid 40 and reduce temperature changes in the shock absorber, thereby reducing changes in the damping force characteristics (damping force characteristics relative to piston speed) that are caused by changes in liquid temperature.

[0138] The shock absorber 100 of this embodiment includes a cylinder 101, a piston 102 that is movably inserted into the cylinder 101 and divides the cylinder 101 into an expansion-side chamber 104 and a compression-side chamber 105 filled with liquid, a rod 103 that is connected to the piston 102, a reservoir 108 that stores liquid, a suction passage 110 that allows only the flow of hydraulic oil from the reservoir 108 to the compression-side chamber 105, a straightening passage 111 that allows only the flow of hydraulic oil from the compression-side chamber 105 to the expansion-side chamber 104, a discharge passage 106 that communicates between the expansion-side chamber 104 and the reservoir 108, and a damping valve 1 that is provided in the discharge passage 106 with the expansion-side chamber 104 upstream of the port 2a and the reservoir 108 downstream of the port 2a.

[0139] The shock absorber 100 configured in this manner is configured as a uniflow type shock absorber in which liquid is always discharged from inside the cylinder 101 through the discharge passage 106 to the reservoir 108 when the shock absorber expands or contracts, and resistance to this liquid flow is provided by a single damping valve 1 with good responsiveness, thereby improving the damping force generation responsiveness.

[0140] When the damping valve 1 equipped with the solenoid 40 is applied to the uniflow type shock absorber 100, the response of the damping force generation can be improved regardless of the direction of expansion and contraction of the shock absorber 100, but it may also be applied to a biflow type shock absorber. There are two types of biflow type shock absorbers: a mono-tube type shock absorber equipped with an air chamber inside the cylinder and a twin-tube type shock absorber with a reservoir outside the cylinder. In the case of a mono-tube type shock absorber, the piston is provided with an extension side passage that allows the flow of liquid from the extension side chamber to the compression side chamber and a compression side passage that allows the flow of liquid from the compression side chamber to the extension side chamber. In the case of a twin-tube type shock absorber, in addition to these extension side passage and compression side passage, a suction passage that allows the flow of liquid from a reservoir provided outside the cylinder to the compression side chamber and a discharge passage that allows the flow of liquid from the compression side chamber to the reservoir are provided. The solenoid valve 24 equipped with the solenoid 40 and the damping valve 1 can be installed in any of the extension side passage, the compression side passage and the discharge passage. In this manner, a shock absorber equipped with the solenoid valve 24 or the damping valve 1 can adjust the magnitude of the damping force generated by changing the amount of current supplied to the solenoid 40. In the event of a failure, the back pressure of the leaf valve 3 can be set by setting the biasing force of the spring 47 of the solenoid 40, thereby optimizing the damping force generated by the shock absorber 100 in the event of a failure.

[0141] Furthermore, in the damping valve 1 of this embodiment, the port 2a of the disk 2, which opens and closes the passage 10e provided in the base 10a of the valve holding member 10, is opened and closed by the leaf valve 3, so that the damping force can be changed in two stages. However, if it is not necessary to change the damping force in two stages, a structure may be adopted in which the disk 2 is eliminated, the base 10a of the valve holding member 10 is used as a disk, the passage 10e of the base 10a is used as a port, a valve seat surrounding the passage 10e is provided in the base 10a, and the passage 10e is opened and closed by the leaf valve 3.

[0142] Although the preferred embodiment of the present invention has been described in detail above, modifications, variations and changes can be made without departing from the scope of the appended claims. [Explanation of symbols]

[0143] 2···Disc, 2a···Port, 2b···Valve seat, 3···Leaf valve, 10d···Orifice (restriction), 22···Valve body, 23···Pilot passage (passage), 24···Solenoid valve, 40···Solenoid, 41···Coil, 42···Filler ring, 42a···Flange, 43···First fixed core, 44···Second fixed core, 44c···Press-fit portion, 45···First movable core, 45a···Sliding cylinder, 45b···Annular bottom portion, 45c···Annular convex portion, 46···Second movable core, 46b···Bottom portion, 47···Spring, 51···Seal ring, 100···Shock absorber, 101···Cylinder, 102···Piston, 103···Rod

Claims

1. A coil and A first fixed core arranged on one end side of the coil in the axial direction; a second stationary core disposed on the other axial end side of the coil with a gap between the first stationary core and the second stationary core; a filler ring having a cylindrical shape and disposed on an inner periphery of the coil and interposed between the first stationary core and the second stationary core; a cylindrical first movable core that is slidably inserted into an inner periphery of the filler ring and disposed between the first fixed core and the second fixed core, and that is attracted to the first fixed core when current is applied to the coil; a second movable core having a bottom, being slidably inserted into the first movable core and disposed between the first and second fixed cores with its bottom facing the second fixed core, and being attracted to the second fixed core when current is applied to the coil; a spring interposed between the first movable core and the first fixed core to bias the first movable core toward the second fixed core, the second fixed core has an annular press-fit portion that is press-fitted into the filler ring and into which the second movable core is slidably inserted, The filler ring has a flange on an inner periphery thereof that faces the press-fit portion in the axial direction, A seal ring is provided between the flange and the press-fit portion to seal between the filler ring and the second fixed core. A solenoid characterized by:

2. A coil and A first fixed core arranged on one end side of the coil in the axial direction; a second stationary core disposed on the other axial end side of the coil with a gap between the first stationary core and the second stationary core; a cylindrical first movable core disposed between the first fixed core and the second fixed core and attracted to the first fixed core when current is applied to the coil; a second movable core having a bottom, being slidably inserted into the first movable core and disposed between the first and second fixed cores with its bottom facing the second fixed core, and being attracted to the second fixed core when current is applied to the coil; A cylindrical spring bearing connected to the first movable core; a spring interposed between the first movable core and the first fixed core to bias the first movable core toward the second fixed core, the first movable core has a sliding cylinder that is in sliding contact with an outer periphery of the second movable core, and an annular bottom portion that protrudes from one end of the sliding cylinder toward an inner periphery, the spring bearing is cylindrical, has an outer periphery of one end connected to an inner periphery of the annular bottom portion, and has an annular spring support portion protruding inward from the inner periphery of the other end, One end of the spring abuts against the first fixed core, and the other end is inserted into the spring bearing and abuts against the spring support portion. A solenoid characterized by:

3. A coil and A first fixed core arranged on one end side of the coil in the axial direction; a second stationary core disposed on the other axial end side of the coil with a gap between the first stationary core and the second stationary core; a cylindrical first movable core disposed between the first fixed core and the second fixed core and attracted to the first fixed core when current is applied to the coil; a second movable core having a bottom, being slidably inserted into the first movable core and disposed between the first and second fixed cores with its bottom facing the second fixed core, and being attracted to the second fixed core when current is applied to the coil; a spring interposed between the first movable core and the first fixed core to bias the first movable core toward the second fixed core, the second fixed core is annular and has a portion into which the second movable core is slidably inserted on an inner periphery thereof, The axial movement of the second movable core is guided only by bringing the second movable core into sliding contact with the first movable core and the portion of the second fixed core. A solenoid characterized by:

4. The outer diameter of the second movable core is constant.

4. The solenoid according to claim 3.

5. A filler ring having a cylindrical shape and disposed on an inner periphery of the coil and interposed between the first fixed iron core and the second fixed iron core, The first movable core is slidably inserted into the inner periphery of the filler ring.

5. A solenoid according to claim 3 or 4.

6. a filler ring having a cylindrical shape and disposed on an inner periphery of the coil and interposed between the first stationary core and the second stationary core; The first movable core is slidably inserted into the inner periphery of the filler ring, The second fixed core has an annular press-fit portion that is press-fitted into the filler ring and into which the second movable core is slidably inserted.

3. The solenoid of claim 2.

7. 7. A solenoid valve including the solenoid according to claim 1 and disposed in a passage, a valve body for opening and closing the passage, The solenoid applies a force that is generated when the coil is energized to attract the second movable core toward the second fixed core to the valve body in a direction to close the passage. A solenoid valve characterized by:

8. A cylinder; A rod that is inserted into the cylinder so as to be movable in the axial direction; a disk having a port through which liquid flows when the cylinder and the rod move relative to each other in the axial direction and a valve seat surrounding the port; a leaf valve that opens and closes the port by being seated on and removed from the valve seat; a pilot passage having a restriction provided therein and reducing the pressure on the upstream side of the port and directing it to the rear surface of the leaf valve; a solenoid valve for controlling the pressure behind the leaf valve; and a solenoid according to any one of claims 1 to 6, which applies a thrust force to the solenoid valve, the thrust force being generated when the coil is energized, and which attracts the second movable core toward the second fixed core. A shock absorber characterized by:

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