Solenoids, electromagnetic valves, and shock absorbers

Abstract

To provide a solenoid, a solenoid valve, and a shock absorber that can reduce the thrust of a solenoid applied to an object when the amount of current supplied to the solenoid is small, and can urge the object in the same direction as the thrust when the solenoid is energized, even when the solenoid is not energized.SOLUTION: A solenoid S1 includes a first fixed core 5 and a second fixed core 6 located at one and the other axial ends of the coil, a first movable core 7 and a second movable core 8 located between them and attracted to the first fixed core 5 and the second fixed core 6, respectively, when a current is passed through the coil, and a spring 9 which urges the first movable core 7 towards the second fixed core 6. The first movable core 7 includes an inner and outer cylindrical portion arranged double inside and outside, a connecting portion connecting one end of the inner cylindrical portion and the outer cylindrical portion, and an inner bottom portion located at the other end of the inner cylindrical portion. The second movable core 8 is cylindrical with a bottom and has an outer bottom portion and an intermediate cylindrical portion standing on the outer peripheral edge of the outer bottom portion, and the intermediate cylindrical portion is slidably inserted inside the outer cylindrical portion with the outer bottom portion facing towards the second fixed core side.SELECTED DRAWING: Figure 7

Description

Technical Field

[0001] The present invention relates to a solenoid, a solenoid-equipped solenoid valve, and a shock absorber equipped with a solenoid valve including a solenoid.

Background Art

[0002] Conventionally, some solenoids include a coil and a movable iron core that generates a magnetic field when current is applied to the coil, and magnetic flux flows to attract the movable iron core in one direction along the axis of the coil. The force attracting the movable iron core is used as a thrust force to apply it to another member (object), and the thrust force can be changed according to the amount of current supplied. Such a solenoid is used, for example, in a solenoid valve.

[0003] And, in such a solenoid valve, there is a valve body provided in the middle of a pressure control passage, which, in addition to the solenoid, includes a valve body that opens and closes the pressure control passage and a spring that biases the valve body in the opening direction. The solenoid gives a thrust force in the closing direction to the valve body. According to this solenoid valve, the higher the amount of current supplied to the solenoid, the higher the opening pressure of the solenoid valve, and the pressure on the upstream side of the solenoid valve can be increased. Such a solenoid valve is used, for example, in a shock absorber.

[0004] And, in such a shock absorber, in addition to the solenoid valve, there is a main passage through which liquid flows when the shock absorber expands and contracts, and a main valve body that opens and closes this main passage. A pressure control passage provided with a solenoid valve is connected to a back pressure chamber formed on the back surface of the main valve body. According to this shock absorber, the higher the amount of current supplied to the solenoid to increase the opening pressure of the solenoid valve, the higher the back pressure (pressure in the back pressure chamber) of the main valve body, and the generated damping force can be increased (for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] Here, when a shock absorber is used for a vehicle suspension or the like, in order to improve the ride comfort during normal driving when the vehicle travels on a good road, it is preferable to reduce the damping force generated during normal driving. And in a conventional shock absorber equipped with a solenoid-including solenoid valve, since the damping force generated when the amount of current supplied to the solenoid is reduced can be reduced, the power consumption during normal driving can be suppressed and power can be saved. However, in a conventional shock absorber, when the solenoid is de-energized during a fail, if the solenoid valve is fully opened and the back pressure of the main valve body becomes minimum, the damping force during the fail will be insufficient.

[0007] Therefore, the valve body of the solenoid valve provided in the shock absorber described in Japanese Patent Application Laid-Open No. 2014-173716 has two opening / closing portions that open and close a pressure control passage. And one of the opening / closing portions functions as an opening / closing portion during pressure control that is biased in the opening direction by a spring and is given a thrust in the closing direction by a solenoid. On the other hand, the other opening / closing portion closes the downstream side of the portion opened and closed by one of the opening / closing portions in the pressure control passage in a state where one of the opening / closing portions is fully opened by the biasing force of the spring when the solenoid is de-energized.

[0008] Furthermore, the shock absorber is provided with a fail passage that is connected between the portion opened and closed by one of the opening / closing portions and the portion opened and closed by the other opening / closing portion in the pressure control passage and has a passive valve provided therein. Thereby, when the pressure control passage is blocked by the other opening / closing portion of the solenoid valve when the solenoid is de-energized, the liquid in the back pressure chamber passes through the fail passage, and the back pressure of the main valve body is set to the opening pressure of the passive valve. For this reason, even in a conventional shock absorber, the damping force of the shock absorber does not become insufficient during a fail.

[0009] However, if two passages, a pressure control passage and a fail passage, are provided as passages connected to the back pressure chamber to set the back pressure of the main valve body, as in the above shock absorber, and the passage connected to the back pressure chamber is switched depending on whether the solenoid is energized or not, the shock absorber structure becomes complicated and costly.However, if the valve body of the solenoid valve is biased in the closing direction by a spring and a thrust in the opening direction is applied to the valve body by the solenoid, it is not necessary to switch the passage connected to the back pressure chamber depending on whether the solenoid is energized or not, but the amount of current supplied to the solenoid must be increased when the generated damping force is reduced, which results in higher power consumption during normal driving.

[0010] In other words, when a solenoid is used in an electromagnetic valve that varies the damping force of a shock absorber, it is sometimes desirable to reduce the thrust applied to an object such as a valve body when the amount of current supplied to the solenoid is small, and to urge the object in the same direction as the thrust even when the solenoid is not energized, but this is not possible with conventional solenoids. For this reason, when a conventional solenoid is used in an electromagnetic valve that varies the damping force of a shock absorber, problems arise such as a complex shock absorber structure and increased power consumption during normal vehicle driving.

[0011] Therefore, the present invention has been devised to solve such problems, and aims to provide a solenoid, an electromagnetic valve, and a shock absorber that can reduce the thrust of the solenoid applied to an object when the amount of current supplied to the solenoid is small, and can urge the object in the same direction as the thrust when the solenoid is energized even when the solenoid is not energized. [Means for solving the problem]

[0012] A solenoid that solves the above problem comprises a first fixed iron core and a second fixed iron core located at one and the other axial ends of a coil, a first movable iron core and a second movable iron core located between the first fixed iron core and the second fixed iron core and attracted to the first fixed iron core and the second fixed iron core, respectively, when current is passed through the coil, and a spring that urges the first movable iron core toward the second fixed iron core, wherein the first movable iron core has an inner and outer cylindrical portion arranged double, an inner and outer cylindrical portion, a connecting portion connecting one axial end of the inner cylindrical portion and the outer cylindrical portion, and an inner bottom portion located at the other end of the inner cylindrical portion, the second movable iron core is cylindrical with a bottom and has an outer bottom portion and an intermediate cylindrical portion that stands on the outer peripheral edge of the outer bottom portion and has an inner diameter larger than the outer diameter of the inner cylindrical portion, and the intermediate cylindrical portion is slidably inserted inside the outer cylindrical portion with the outer bottom portion facing toward the second fixed iron core, and one end of the spring is inserted inside the inner cylindrical portion and is interposed between the inner bottom portion and the first fixed iron core.

[0013] According to the above configuration, when the solenoid is not energized, the first movable core moves toward the second fixed core due to the biasing force of the spring, and when the movement of the first movable core toward the second fixed core relative to the second movable core is restricted, the biasing force of the spring is transmitted from the first movable core to the second movable core. On the other hand, when the solenoid is energized, if the first movable core is attracted to the first fixed core and moves in the direction of attraction, the spring is compressed by the first movable core, and the biasing force of the spring is no longer transmitted to the second movable core. Furthermore, when the solenoid is energized, the second movable core is attracted to the second fixed core, and the force attracting the second movable core to the second fixed core increases as the amount of current supplied to the solenoid increases.

[0014] Therefore, when the solenoid is energized, the force attracting the second movable core is applied as a thrust to the object. The greater the amount of current supplied to the solenoid, the greater the thrust applied to the object. The smaller the amount of current supplied to the solenoid, the smaller the thrust applied to the object. Furthermore, when the solenoid is de-energized, the biasing force of the spring acts on the object via the first movable core and the second movable core. Since the direction of the biasing force of the spring is the same as the direction of the force attracting the second movable core when the solenoid is energized, the above configuration allows the object to be biased in the same direction as when the solenoid is energized, even when the solenoid is de-energized.

[0015] Furthermore, with the above configuration, when the coil is excited, a magnetic path passes through the first fixed core, the first movable core, the second movable core, and the second fixed core, so that the first movable core is attracted to the first fixed core and the second movable core is attracted to the second fixed core. Furthermore, the solenoid can be made small while ensuring a space for accommodating the spring inside the first movable core.

[0016] Furthermore, the solenoid may be provided in a solenoid valve provided in the pressure control passage, and the solenoid valve may include, in addition to the solenoid, a valve body that opens and closes the pressure control passage, and the force generated by the solenoid when current is applied to the coil applies to the valve body in a direction that closes the pressure control passage, attracting the second movable iron core toward the second fixed iron core. In this way, the valve opening pressure of the solenoid valve can be adjusted by changing the amount of current supplied to the solenoid, and the pressure upstream of the solenoid valve can be set as the valve opening pressure of the solenoid valve.

[0017] Furthermore, as described above, the greater the amount of current supplied to the solenoid, the greater the thrust applied to the object. Therefore, in the solenoid valve, the greater the amount of current supplied to the solenoid, the greater the thrust that the solenoid applies to the valve element in the closing direction, thereby increasing the valve-opening pressure of the solenoid valve. In addition, as described above, in the solenoid, even when de-energized, the spring can urge the object in the same direction as the thrust when energized, so in the solenoid valve, the valve-opening pressure when de-energized can be determined according to the specifications of the spring.

[0018] Furthermore, an electromagnetic valve including the solenoid may be provided in a shock absorber, and the shock absorber may comprise a cylinder, a rod inserted into the cylinder so as to be movable in the axial direction, a main passage through which liquid flows when the cylinder and the rod move relative to each other in the axial direction, a main valve body that opens and closes the main passage, a pressure introduction passage with a restriction provided midway through to reduce and introduce pressure in the main passage upstream of the main valve body to the back surface of the main valve body, and a pressure control passage connected downstream of the restriction in the pressure introduction passage and in which the electromagnetic valve is provided.

[0019] By doing so, when the cylinder and the rod move relative to each other in the axial direction, if resistance is applied to the flow of the liquid passing through the main passage by the main valve body, the shock absorber can generate a damping force due to the resistance. Further, since the back pressure of the main valve body is set to the valve opening pressure of the solenoid valve, the back pressure of the main valve body can be adjusted by changing the amount of current supplied to the solenoid. And the higher the back pressure of the main valve body, the more difficult it is for the main valve body to open and the greater the generated damping force. Therefore, according to the above configuration, the damping force generated by changing the amount of current supplied to the solenoid can be adjusted in size.

[0020] Furthermore, as described above, in the solenoid valve, the higher the amount of current supplied to the solenoid, the higher the valve opening pressure of the solenoid valve. Therefore, in the shock absorber, the higher the amount of current supplied to the solenoid, the higher the back pressure of the main valve body, and the greater the generated damping force. That is, in the shock absorber, since the damping force generated when the amount of current supplied to the solenoid is small can be reduced, when the shock absorber is used for a vehicle suspension, the power consumption during normal driving can be reduced. Also, this can suppress the heat generation of the solenoid and reduce the temperature change of the shock absorber, so that the change in the damping force characteristic (the characteristic of the damping force with respect to the piston speed) due to the change in the liquid temperature can be reduced.

[0021] In addition, as described above, in the solenoid valve, the valve opening pressure at the time of non - energization can be determined according to the specification of the spring. Therefore, in the shock absorber, the back pressure of the main valve body can be increased even when the solenoid is not energized. Thereby, in the shock absorber, it is possible to prevent the damping force from being insufficient during a failure. Further, in the shock absorber, a pressure control passage may be provided as a passage for setting the back pressure of the main valve body. Since it is not necessary to switch the passage for setting the back pressure between when the solenoid is energized and when it is not energized, the structure of the shock absorber can be prevented from becoming complicated and the cost can be reduced.

Advantages of the Invention

[0022] According to the solenoid, solenoid valve, and shock absorber of the present invention, when the amount of supply current to the solenoid is small, the thrust of the solenoid applied to the object can be reduced, and the object can be biased in the same direction as the thrust during energization even when the solenoid is not energized. [Brief explanation of the drawings]

[0023] [Figure 1] 1 is a vertical cross-sectional view of a shock absorber provided with an electromagnetic valve including a solenoid according to a first embodiment of the present invention; [Figure 2] 1 is an enlarged longitudinal sectional view showing a solenoid valve including a solenoid according to a first embodiment of the present invention; [Figure 3] FIG. 2 is a partially enlarged cross-sectional view of a solenoid according to the first embodiment of the present invention. [Figure 4] 4 is a characteristic diagram showing the relationship between the amount of current supplied to the solenoid according to the first embodiment of the present invention and the force acting in the direction of depressing the valve body. FIG. [Figure 5] FIG. 2 is a partially enlarged cross-sectional view showing a first modified example of the solenoid according to the first embodiment of the present invention. [Figure 6] FIG. 10 is a partially enlarged cross-sectional view showing a second modified example of the solenoid according to the first embodiment of the present invention. [Figure 7] 1(a) is a partially enlarged cross-sectional view of a solenoid according to a second embodiment of the present invention, and FIG. 1(b) is an enlarged view of a Y portion of FIG. DETAILED DESCRIPTION OF THE INVENTION

[0024] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described with reference to the drawings. The same reference numerals used throughout the several drawings indicate the same or corresponding parts.

[0025] In each embodiment, the solenoid is used in a solenoid valve, which is used in a shock absorber, which is further used in a vehicle suspension. However, the purposes of use of the solenoid, the solenoid valve including the solenoid, and the shock absorber including the solenoid valve according to the present invention are not limited to the above and can be changed as appropriate.

[0026] First Embodiment As shown in Fig. 1, a shock absorber D provided with a solenoid valve V according to the first embodiment of the present invention includes a cylinder 1, a piston 10 slidably inserted into the cylinder 1, and a piston rod 11 having one end connected to the piston 10 and the other end protruding outside the cylinder 1. The cylinder 1 is connected to one of the vehicle body and the axle in the vehicle, and the piston rod 11 is connected to the other. In this way, the shock absorber D is interposed between the vehicle body and the axle.

[0027] When the vehicle travels on a bumpy road surface and the wheels vibrate up and down, the piston rod 11 enters and exits the cylinder 1, the shock absorber D expands and contracts, and the piston 10 moves up and down (in the axial direction) in the cylinder 1 in Fig. 1. Although Fig. 1 shows a state where the piston rod 11 protrudes upward from the cylinder 1, the shock absorber D may be attached to the vehicle in any orientation.

[0028] Subsequently, an annular head member 12 that allows the insertion of the piston rod 11 inside is attached to one end portion of the cylinder 1 in the axial direction. This head member 12 slidably supports the piston rod 11 and closes one end of the cylinder 1. On the other hand, the other end of the cylinder 1 is closed by a bottom cap 13. In this way, the inside of the cylinder 1 is sealed, and a liquid and a gas are enclosed in the cylinder 1.

[0029] More specifically, a free piston 14 is slidably inserted into the cylinder 1 on the side opposite to the piston rod 11 as viewed from the piston 10. A liquid chamber L filled with a liquid such as hydraulic oil is formed on the piston 10 side of the free piston 14. On the other hand, a gas chamber G filled with compressed gas is formed on the side opposite to the piston 10 as viewed from the free piston 14.

[0030] In this way, the liquid chamber L and the gas chamber G in the cylinder 1 are partitioned by the free piston 14. When the piston rod 11 enters and exits the cylinder 1 during the expansion and contraction of the shock absorber D, the free piston 14 moves up and down (in the axial direction) in the cylinder 1 in FIG. 1 to expand or contract the gas chamber G, compensating for the volume of the piston rod 11 that enters and exits the cylinder 1.

[0031] Note that the liquid chamber L and the gas chamber G may also be partitioned by a bladder or bellows, etc. other than the free piston 14. That is, the configuration of the movable partition wall forming the expandable gas chamber G is not limited to the free piston 14 and can be appropriately changed. Furthermore, the configuration for compensating the volume of the piston rod 11 that enters and exits the cylinder 1 is not limited to the gas chamber G and can be appropriately changed. For example, instead of the gas chamber G, a reservoir for accommodating liquid and gas may be provided, and liquid may be exchanged between the cylinder and the reservoir during the expansion and contraction of the shock absorber. Also, the shock absorber D may be of a double-rod type with piston rods provided on both sides of the piston. In that case, the configuration itself for compensating the piston rod volume can be omitted.

[0032] Subsequently, the liquid chamber L in the cylinder 1 is partitioned by the piston 10 into the extending chamber L1 on the piston rod 11 side and the pressure chamber L2 on the opposite side (opposite to the piston rod side). As shown in FIG. 2, the piston 10 is in the shape of a bottomed cylinder and includes a cylindrical portion 10b to which a piston ring 10a that slidably contacts the inner circumference of the cylinder 1 is attached on the outer circumference, and a bottom portion 10c that closes one end of the cylindrical portion 10b. Hereinafter, for the convenience of explanation, unless otherwise specifically explained, the directions that are up and down in FIG. 2 will simply be referred to as "up" and "down".

[0033] Then, the piston 10 is arranged with the bottom portion 10c facing downward and the cylindrical portion 10b facing upward, and the cylindrical portion 10b is connected to a toped cylindrical case portion 11a formed at the tip of the piston rod 11 via a cylindrical guide 15. An annular valve seat member 16 is fixed between the lower end of the guide 15 and the piston 10. Further, inside the guide 15, a main valve body 2 that seats and leaves the valve seat member 16 is provided so as to be movable up and down.

[0034] The main valve element 2 has a first valve element portion 2A and a second valve element portion 2B that can be separated into upper and lower portions, and an intermediate chamber L3 is formed between the main valve element 2 and a bottom portion 10c of the piston 10. This intermediate chamber L3 is separated from the compression-side chamber L2 by the piston 10. In addition, extension-side and compression-side ports 10d, 10e that communicate between the intermediate chamber L3 and the compression-side chamber L2 are formed in the bottom portion 10c of the piston 10. Furthermore, an expansion-side valve 20 that opens and closes the outlet of the expansion-side port 10d is stacked below the bottom portion 10c, and a compression-side valve 21 that opens and closes the outlet of the compression-side port 10e is stacked above the bottom portion 10c.

[0035] The inlet of the expansion-side port 10d opens to the intermediate chamber L3, and the pressure in the intermediate chamber L3 acts in a direction to open the expansion-side valve 20. When the expansion-side valve 20 opens due to the pressure in the intermediate chamber L3, the liquid in the intermediate chamber L3 flows through the expansion-side port 10d to the compression-side chamber L2. On the other hand, the inlet of the compression-side port 10e opens to the compression-side chamber L2, and the pressure in the compression-side chamber L2 acts in a direction to open the compression-side valve 21. When the compression-side valve 21 opens due to the pressure in the compression-side chamber L2, the liquid in the compression-side chamber L2 flows through the compression-side port 10e to the intermediate chamber L3.

[0036] As described above, the main valve element 2 has a first valve element portion 2A and a second valve element portion 2B that can be separated into upper and lower portions. The first valve element portion 2A is annular, and its tip portion is inserted into the inside of the valve seat member 16 so as to be freely axially movable, and is capable of being seated on and removed from the valve seat member 16. Meanwhile, the second valve element portion 2B includes a head portion 2a and a flange portion 2b that protrudes outward from the lower end of the head portion 2a. The head portion 2a and the flange portion 2b of the second valve element portion 2B are in sliding contact with the inner periphery of the guide 15, and the lower end of the second valve element portion 2B is capable of being seated on and removed from the first valve element portion 2A.

[0037] Further, the guide 15 is formed with a through hole 15a that opens into the extensor chamber L1, and the pressure in the extensor chamber L1 acts in a direction that pushes up both the first valve body portion 2A and the second valve body portion 2B, causing the first valve body portion 2A to separate from the valve seat member 16. When the first valve body portion 2A moves upward together with the second valve body portion 2B and separates from the valve seat member 16 in response to the pressure in the extensor chamber L1, the liquid in the extensor chamber L1 flows through the gap formed between the first valve body portion 2A and the valve seat member 16 and heads toward the intermediate chamber L3.

[0038] The intermediate chamber L3 is formed on the inner circumferential side of the valve seat member 16, the first valve body portion 2A, and the cylindrical portion 10b of the piston 10, between the bottom portion 10c of the piston 10 and the second valve body portion 2B. The pressure in this intermediate chamber L3 acts in a downward direction on the first valve body portion 2A and in an upward direction on the second valve body portion 2B. That is, the pressure in the intermediate chamber L3 separates the first valve body portion 2A and the second valve body portion 2B vertically and acts in a direction that causes the second valve body portion 2B to separate from the first valve body portion 2A. When the second valve body portion 2B moves upward and separates from the first valve body portion 2A in response to the pressure in the intermediate chamber L3, the liquid in the intermediate chamber L3 flows through the gap formed between the first valve body portion 2A and the second valve body portion 2B and through the through hole 15a and heads toward the extensor chamber L1.

[0039] To summarize the above, in this embodiment, a main passage M that connects the extensor chamber L1 and the pressure chamber L2 is formed by the through hole 15a of the guide 15, the intermediate chamber L3, and the extensor and pressure ports 10d, 10e. A main valve body 2 is provided in the main passage M, and an extensor valve 20 and a pressure valve 21 are provided in series with this main valve body 2.

[0040] A back pressure chamber L4 is formed above the upper surface of the flange portion 2b, which forms the back surface of the main valve element 2. The pressure in this back pressure chamber L4 acts in a direction that presses down the second valve element 2B together with the first valve element 2A. The second valve element 2B also has a pressure introduction passage p1 that is provided with a throttle O midway and reduces the pressure in the expansion-side chamber L1 and leads the pressure to the back pressure chamber L4, a pressure control passage p2 that is connected to the pressure introduction passage p1 downstream of the throttle O, and a pressure reduction passage p3 that allows only the flow of liquid from the intermediate chamber L3 to the back pressure chamber L4 and reduces the pressure in the intermediate chamber L3 and leads the pressure to the back pressure chamber L4.

[0041] A solenoid valve V including a solenoid S1 according to this embodiment is provided in the pressure control passage p2. The solenoid valve V includes a spool 3 as a valve element that opens and closes the pressure control passage p2 by engaging with and disengaging from a valve seat 22 provided in the second valve body portion 2B, and a solenoid S1 that applies a downward thrust to the spool 3. When the spool 3 moves downward due to the thrust of the solenoid S1, it seats on the valve seat 22 and closes the pressure control passage p2. In this way, the thrust of the solenoid S1 acts in the direction of closing the spool 3.

[0042] On the other hand, the pressure in the back pressure chamber L4 acts in a direction pushing up the spool 3. Then, when the pressure in the back pressure chamber L4 increases and the upward force caused by that pressure overcomes the downward force caused by the solenoid S1, etc., the spool 3 moves upward and lifts off the valve seat 22, opening the pressure control passage p2. In other words, the pressure in the back pressure chamber L4 acts in a direction to open the spool 3, and when the pressure in the back pressure chamber L4 reaches the valve opening pressure of the spool 3, the spool 3 opens the pressure control passage p2. This movement of the spool 3 lifting off the valve seat 22 and opening and closing the pressure control passage p2 is also referred to as the opening and closing of the solenoid valve V.

[0043] Also, in this embodiment, when the solenoid valve V opens, the liquid in the back pressure chamber L4 flows out through the pressure control passage p2 into the upper gap L5 formed between the head 2a of the second valve body portion 2B and the solenoid S1. This upper gap L5 is communicated with the intermediate chamber L3 by a communication passage p4 formed in the second valve body portion 2B. Thereby, when the solenoid valve V opens, the liquid flows from the back pressure chamber L4 through the pressure control passage p2 toward the upper gap L5 and also from the upper gap L5 through the communication passage p4 toward the intermediate chamber L3. Further, the pressures in the upper gap L5 and the intermediate chamber L3 become substantially the same due to the communication passage p4.

[0044] Next, the solenoid S1 according to this embodiment includes a coil 4 accommodated along the axial direction in the case portion 11a of the piston rod 11, a first fixed iron core 5 disposed above this coil 4, a second fixed iron core 6 disposed below the coil 4 with a gap from the first fixed iron core 5, a first movable iron core 7 and a second movable iron core 8 disposed between the first fixed iron core 5 and the second fixed iron core 6 so as to be vertically movable, a spring 9 that biases the first movable iron core 7 downward, a leaf spring 90 that restricts the downward movement amount of the first movable iron core 7 with respect to the second movable iron core 8, and a leaf spring 91 that restricts the downward movement amount of the second movable iron core 8.

[0045] Here, the direction along the center line X passing through the center of the coil 4 is the axial direction of the coil 4, and the up and down mentioned here correspond to both sides in the axial direction of the coil 4. Therefore, it can be said that the first fixed iron core 5 is disposed on one end side in the axial direction of the coil 4, and the second fixed iron core 6 is disposed on the other end side in the axial direction of the coil 4. Also, the spring 9 biases the first movable iron core 7 toward the second fixed iron core 6 side, the leaf spring 90 functions as a restricting portion that restricts the movement of the first movable iron core 7 toward the second fixed iron core 6 side with respect to the second movable iron core 8, and the leaf spring 91 functions as a restricting portion that restricts the movement of the second movable iron core 8 toward the second fixed iron core 6 side.

[0046] Hereinafter, each part constituting the solenoid S1 according to this embodiment will be described in detail.

[0047] Coil 4 is integrated with a harness 40 for supplying electricity by molded resin, and this harness 40 passes through the inside of piston rod 11, extends to the outside of shock absorber D and is connected to a power source. Furthermore, first fixed core 5, second fixed core 6, first movable core 7, and second movable core 8 are each made of a magnetic material, and when electricity is passed through coil 4, magnetic flux is generated, and this magnetic flux flows through the first fixed core 5, first movable core 7, second movable core 8, second fixed core 6, and case portion 11a, and first movable core 7 is attracted upward toward first fixed core 5, and second movable core 8 is attracted downward toward second fixed core 6.

[0048] An annular filler ring 41 made of a non-magnetic material is interposed between the first stator core 5 and the second stator core 6, and this filler ring 41 forms a magnetic gap between the first stator core 5 and the second stator core 6. Furthermore, the first movable core 7 and the second movable core 8 are arranged inside the filler ring 41. Both the first movable core 7 and the second movable core 8 are cylindrical with a bottom, and the first movable core 7 is inserted inside the second movable core 8 so as to be movable up and down (axially), and the second movable core 8 is inserted inside the filler ring 41 so as to be movable up and down (axially).

[0049] 3, the second movable core 8, which is an outer cylinder, has an outer bottom 8a and an outer cylinder portion 8b standing on the outer peripheral edge of the outer bottom 8a, with the outer bottom 8a facing downward (toward the second fixed core 6) and the outer cylinder portion 8b in sliding contact with the inner periphery of the filler ring 41. On the other hand, the first movable core 7, which is an inner cylinder, has an inner bottom 7a, an inner cylinder portion 7b standing on the outer peripheral edge of the inner bottom 7a, and an annular guide portion 7c located on the outer periphery of the tip of the inner cylinder portion 7b, with the inner bottom 7a facing downward (toward the second fixed core 6) and the inner cylinder portion 7b inserted into the outer cylinder portion 8b, and the guide portion 7c protruding upward from the outer cylinder portion 8b in sliding contact with the inner periphery of the filler ring 41.

[0050] A communication hole 7d penetrating the thickness is formed in the inner bottom 7a of the first movable core 7, and liquid can move through the communication hole 7d with relatively little resistance. As a result, liquid is not trapped above the first movable core 7 (on the side of the first fixed core 5), ensuring smooth vertical movement of the first movable core 7. A spring 9 is inserted inside the inner cylinder portion 7b of the first movable core 7. In the present embodiment, the spring 9 is a coil spring, and one end of the spring 9 abuts against the inner bottom 7a. On the other hand, the other end of the spring 9 is supported by the first fixed core 5, and the spring 9 biases the first movable core 7 downward.

[0051] Also, the inner diameter of the outer cylinder portion 8b of the second movable core 8 is larger than the outer diameter of the inner cylinder portion 7b of the first movable core 7, and an annular gap is formed between the outer cylinder portion 8b and the inner cylinder portion 7b, allowing liquid to move through the gap with relatively little resistance. A communication hole 8c penetrating the thickness is formed in the outer bottom 8a of the second movable core 8, and liquid can move through the communication hole 8c with relatively little resistance. As a result, it is possible to suppress the generation of a damping force that traps liquid in the space L6 formed above the tip of the outer cylinder portion 8b (on the side of the first fixed core 5) or the space L7 formed above the outer bottom 8a (on the side of the first fixed core 5) and hinders the movement of the second movable core 8.

[0052] Furthermore, in the present embodiment, since the first movable core 7 moves vertically (in the axial direction) while being supported by the filler ring 41 at its guide portion 7c, it does not become eccentric with respect to the filler ring 41 during the movement. The filler ring 41 is sandwiched between the first fixed core 5 and the second fixed core 6 and is fixedly provided with respect to them. Therefore, the filler ring 41 prevents the first movable core 7 from shifting in a direction (radial direction) orthogonal to the center line X of the coil 4. For this reason, it is possible to prevent the first movable core 7 from shifting in the radial direction during its movement and sandwiching the outer cylinder portion 8b of the second movable core 8 between it and the filler ring 41, which would increase the friction during the movement of the second movable core 8. As a result, smooth vertical movement of the second movable core 8 is ensured.

[0053] Next, leaf springs 90, 91 which function as restriction members as described above are arranged above and below the outer bottom 8a of the second movable core 8. More specifically, the upper leaf spring 90, which is the first restriction member, is located between the outer bottom 8a of the second movable core 8 and the inner bottom 7a of the first movable core 7 which faces it vertically, and the lower leaf spring 91, which is the second restriction member, is located between the outer bottom 8a of the second movable core 8 and the second fixed core 6 which faces it vertically.

[0054] The upper leaf spring 90 includes an annular seat portion laminated on the outer bottom portion 8a of the second movable core 8, and a plurality of legs extending radially from this seat portion toward the outer periphery and standing obliquely upward. On the other hand, the lower leaf spring 91 includes an annular seat portion laminated on the second fixed core 6, and a plurality of legs extending from this seat portion toward the inner periphery and standing obliquely upward. As such, the upper and lower leaf springs 90, 91 each include a plurality of legs, and a gap is formed between adjacent legs, so that the leaf springs 90, 91 do not obstruct the flow of liquid.

[0055] Then, as the first movable core 7 moves downward relative to the second movable core 8, the inner bottom portion 7a of the first movable core 7 hits the leaf spring 90. This restricts the downward movement of the first movable core 7 relative to the second movable core 8, and thereafter the first movable core 7 moves downward together with the second movable core 8. Furthermore, as the second movable core 8 moves downward, the outer bottom portion 8a of the second movable core 8 hits the leaf spring 91 and compresses it, preventing further downward movement.

[0056] A through-hole is formed in the central portion of the second fixed core 6, and the shaft portion 3a of the spool 3 is movably inserted into the through-hole. The tip of the shaft portion 3a abuts against the outer bottom portion 8a of the second movable core 8. Thus, in a state where the power supply to the coil 4 is cut off, the first movable core 7 moves downward under the biasing force of the spring 9 and abuts against the second movable core 8 via the leaf spring 90, so that the spool 3 receives a downward force due to the biasing force of the spring 9. On the other hand, when the coil 4 is energized to attract the first movable core 7 to the first fixed core 5 and the second movable core 8 to the second fixed core 6, the spring 9 is compressed by the first movable core 7 and its biasing force is not transmitted to the spool 3, but the spool 3 receives a downward force due to the force of attracting the second movable core 8.

[0057] Also, the leaf spring 90, which is the first restricting portion, restricts the approach between the inner bottom portion 7a of the first movable core 7 and the outer bottom portion 8a of the second movable core 8 facing it in the vertical (axial) direction, and prevents the first movable core 7 and the second movable core 8 from attracting each other when the coil 4 is energized. Similarly, the leaf spring 91, which is the second restricting portion, restricts the approach between the outer bottom portion 8a of the second movable core 8 and the second fixed core 6 facing it in the vertical (axial) direction, and prevents the second movable core 8 from attracting to the second fixed core 6 when the coil 4 is energized.

[0058] Note that the first and second restricting portions are not limited to the leaf springs 90 and 91, respectively, and may be non-magnetic rings or sheets such as rubber, synthetic resin, or aluminum. In such a case, it is preferable to arrange the ring or sheet on the outer peripheral side of the entrances and exits of the communication holes 7d and 8c so as not to obstruct the flow of the liquid. Further, if the movement of the first movable core 7 relative to the second movable core 8 and the movement of the second movable core 8 relative to the second fixed core 6 during energization are not obstructed, the first and second restricting portions may be magnetic bodies, and a part of the first movable core 7 or the second movable core 8 may function as the first restricting portion, or a part of the second movable core 8 or the second fixed core 6 may function as the second restricting portion.

[0059] On the other hand, no restricting portion is provided between the first fixed core 5 and the first movable core 7, and when the coil 4 is energized, the first movable core 7 is attracted to the first fixed core 5. In this way, when the first movable core 7 is attracted to the first fixed core 5 when the coil 4 is energized, the spring 9 is compressed by the first movable core 7, and the posture of the first movable core 7 can be stably maintained so that the biasing force of this spring 9 is not transmitted to the second movable core 8 side. However, it is not always necessary for the first movable core 7 to be attracted to the first fixed core 5 when the coil 4 is energized.

[0060] Subsequently, FIG. 4 shows the relationship between the amount of current supplied to the solenoid S1 and the force that the solenoid S1 applies to the spool 3. In FIG. 4, Ia is the minimum amount of current required to attract the first movable core 7, which is in a state separated from the first fixed core 5, to the first fixed core 5, and Ib is the minimum amount of current required to maintain the attracted state of the first fixed core 5 and the first movable core 7. Note that Ic will be described later.

[0061] First, when the amount of current supplied to the coil 4 is zero, that is, when the solenoid S1 is not energized, the first movable core 7 is pushed down by the biasing force of the spring 9 and abuts against the second movable core 8 via the leaf spring 90, and the second movable core 8 is pushed down together with the spool 3. In this way, when the solenoid S1 is not energized, the spool 3 receives a downward force by the spring 9 via the second movable core 8, the leaf spring 90, and the first movable core 7. That is, when the solenoid S1 is not energized, the solenoid S1 applies a downward force caused by the biasing force of the spring 9 to the spool 3.

[0062] Next, when the amount of current supplied to the solenoid S1 is increased, the upward force attracting the first movable core 7 toward the first fixed core 5 increases, and the downward force attracting the second movable core 8 toward the second fixed core 6 also increases. In such a case, in the region where the amount of current supplied to the solenoid S1 is less than Ia, the biasing force of the spring 9 is transmitted to the spool 3, but part of the force of the spring 9 biasing the first movable core 7 downward is offset by the force attracting the first movable core 7 upward (toward the first fixed core 5). For this reason, in the region where the amount of current is less than Ia, the downward force that the solenoid S1 applies to the spool 3 decreases as the amount of current supplied to the solenoid S1 increases.

[0063] On the other hand, when the amount of current supplied to solenoid S1 is increased and the amount of current is equal to or greater than Ia, first movable core 7 is attracted to and attached to first fixed core 5 against the biasing force of spring 9. In this state, the biasing force of spring 9 is no longer transmitted to second movable core 8, and only the force attracting second movable core 8 to second fixed core 6 acts in a direction that pushes down spool 3. This downward force attracting second movable core 8 increases in proportion to the amount of current supplied to solenoid S1, so in the range where the amount of current supplied to solenoid S1 is equal to or greater than Ia, the more the amount of current supplied to solenoid S1 is increased, the greater the downward force that solenoid S1 applies to spool 3 in proportion to the amount of current.

[0064] Conversely, when the amount of current supplied to the solenoid S1 is reduced, the upward force attracting the first movable core 7 to the first fixed core 5 decreases, and the downward force attracting the second movable core 8 to the second fixed core 6 also decreases. Even in such a case, in the region where the amount of current supplied to the solenoid S1 is Ib or more, the first movable core 7 is attracted to the first fixed core 5, and a state is maintained in which the biasing force of the spring 9 is not transmitted to the second movable core 8. For this reason, in the region where the amount of current supplied to the solenoid S1 is Ib or more, the more the amount of current supplied to the solenoid S1 is reduced, the smaller the downward force that the solenoid S1 applies to the spool 3 in proportion to the amount of current.

[0065] On the other hand, when the amount of current supplied to the solenoid S1 is decreased, in the region where the amount of current is less than Ib, the attracting state between the first movable iron core 7 and the first fixed iron core 5 is released by the biasing force of the spring 9, and the biasing force of the spring 9 is transmitted to the second movable iron core 8. For this reason, in the region where the amount of current is less than Ib, the downward force applied by the solenoid S1 to the spool 3 increases as the amount of current supplied to the solenoid S1 is decreased.

[0066] As can be seen from FIG. 4, Ib, which is the minimum amount of current required to maintain the attraction between the first movable iron core 7 and the first fixed iron core 5, is smaller than Ia (Ia > Ib), which is the minimum amount of current required to attract the separated first movable iron core 7 to the first fixed iron core 5. For this reason, the characteristic of the force applied by the solenoid S1 to the spool 3 with respect to the amount of current supplied to the solenoid S1 has a hysteresis characteristic. Note that in FIG. 4, the region where the amount of current supplied to the solenoid S1 is small is exaggerated for easy understanding.

[0067] In the present embodiment, when attempting to control the force applied by the solenoid S1 to the spool 3 by controlling the amount of current supplied to the solenoid S1, after once supplying a current of Ia or more to attract the first movable iron core 7 to the first fixed iron core 5, it is controlled in the range where the amount of current supplied to the solenoid S1 is Ic or more, which is greater than Ib. Thereby, during normal operation of controlling the energization amount to the solenoid S1, since the state where the first movable iron core 7 is attracted to the first fixed iron core 5 is maintained, the amount of current supplied to the solenoid S1 and the downward force applied by the solenoid S1 to the spool 3 are in a proportional relationship, and the force increases as the amount of current supplied to the solenoid S1 is increased.

[0068] In the normal state (when under control), the force that the solenoid S1 exerts on the spool 3 due to the magnetic force generated by energizing the solenoid S1 is called the "thrust" of the solenoid S1. In other words, the thrust of the solenoid S1 is controlled by controlling the amount of current supplied to the solenoid S1. In this embodiment, the amount of current supplied to the solenoid S1 and the thrust that the solenoid S1 exerts on the spool 3 are proportional to each other, so that the thrust increases as the amount of current supplied increases, and decreases as the amount of current supplied decreases.

[0069] On the other hand, in the event of a failure where the solenoid S1 is de-energized, the spool 3 is urged downward by the spring 9 of the solenoid S1, and the urging force is predetermined according to the specifications of the spring 9, such as the spring constant. Furthermore, the direction of the urging force of the spring 9 that urges the spool 3 in the event of a failure (de-energized) is the same as the direction of the thrust applied to the spool 3 in the normal state.

[0070] The operation of the shock absorber D equipped with the electromagnetic valve V including the solenoid S1 according to this embodiment will be described below.

[0071] When the shock absorber D extends, the piston 10 moves upward in the cylinder 1, compressing the extension-side chamber L1. As the pressure in the extension-side chamber L1 increases, the liquid in the extension-side chamber L1 flows into the backpressure chamber L4 through the pressure introducing passage p1, and the pressure in the backpressure chamber L4 increases. When the pressure in the backpressure chamber L4 reaches the valve opening pressure of the spool 3, the spool 3 (solenoid valve V) opens, and the liquid in the backpressure chamber L4 flows through the pressure control passage p2, the upper gap L5, and the communicating passage p4 toward the intermediate chamber L3. As a result, when the shock absorber D extends, the pressure in the backpressure chamber L4 is controlled to the valve opening pressure of the solenoid valve V.

[0072] Furthermore, when the upward force acting on the first valve body portion 2A and the second valve body portion 2B due to the pressure in the expansion-side chamber L1 or the like exceeds the downward force due to the pressure in the back-pressure chamber L4 or the like during expansion of the shock absorber D, the first valve body portion 2A and the second valve body portion 2B move upward. Then, a gap is formed between the first valve body portion 2A and the valve seat member 16, and the liquid in the expansion-side chamber L1 moves through the gap to the intermediate chamber L3, and the liquid in the intermediate chamber L3 opens the expansion-side valve 20 and moves to the compression-side chamber L2.

[0073] In this way, when the shock absorber D extends, the first valve body portion 2A of the main valve body 2 and the extension-side valve 20 open, and the main valve body 2 and the extension-side valve 20 provide resistance to the flow of liquid from the extension-side chamber L1 to the compression-side chamber L2 through the main passage M. Therefore, when the shock absorber D extends, the pressure in the extension-side chamber L1 increases, and the shock absorber D exerts an extension-side damping force that hinders the extension operation.

[0074] Furthermore, during normal operation when the amount of current supplied to the solenoid S1 is controlled, the more current supplied to the solenoid S1, the greater the thrust of the solenoid S1 acting downward (in the closing direction) on the spool 3. Therefore, the more current supplied to the solenoid S1, the higher the valve opening pressure of the spool 3 (solenoid valve V), which in turn increases the pressure in the back pressure chamber L4.

[0075] Furthermore, since the pressure in the back pressure chamber L4 acts downward (in the closing direction) on the second valve body portion 2B and the first valve body portion 2A, the higher the pressure in the back pressure chamber L4 is by increasing the amount of current supplied to the solenoid S1, the higher the valve opening pressure of the first valve body portion 2A in the main valve body 2 and the greater the extension-side damping force generated. In this way, under normal conditions, the magnitude of the extension-side damping force is adjusted by adjusting the valve opening pressure of the spool 3 with the solenoid S1. Note that Figures 2 and 3 show the spool 3 in an open state under normal conditions.

[0076] On the other hand, in the event of a failure in which the energization of the solenoid S1 is cut off, the valve opening pressure of the spool 3 (solenoid valve V) is determined according to the biasing force of the spring 9. For this reason, the pressure in the back pressure chamber L4 during a failure is determined according to the specifications of the spring 9, and the damping force on the extending side generated thereby is determined. As described above, during normal operation, since the biasing force of the spring 9 is not transmitted to the spool 3, the specifications of the spring 9 can be freely set without considering the damping force on the extending side during normal operation.

[0077] Conversely, when the piston 10 moves downward in the cylinder 1 during the contraction of the shock absorber D to compress the pressure side chamber L2 and the pressure in the pressure side chamber L2 increases, the liquid in the pressure side chamber L2 opens the pressure side valve 21 and moves to the intermediate chamber L3, and the liquid in the intermediate chamber L3 moves to the back pressure chamber L4 through the pressure reducing passage p3. At this time, the pressure in the upper gap L5 located on the downstream side of the spool 3 is substantially the same as the pressure in the intermediate chamber L3 and is higher than the pressure in the back pressure chamber L4 located on the upstream side of the spool 3. For this reason, the spool 3 is maintained in a closed state. And in such a state, the thrust of the solenoid S1 acts downward on the second valve body portion 2B via the spool 3.

[0078] Also, as described above, since the pressure in the intermediate chamber L3 acts only upward on the second valve body portion 2B, when the upward force due to the pressure in the intermediate chamber L3 acting on the second valve body portion 2B etc. exceeds the downward force due to the thrust of the solenoid S1 etc., only the second valve body portion 2B moves upward. Then, a gap is formed between the second valve body portion 2B and the first valve body portion 2A, and the liquid in the intermediate chamber L3 moves to the extending side chamber L1 through the gap.

[0079] In this way, when the shock absorber D contracts, the pressure side valve 21 and the second valve body portion 2B of the main valve body 2 open, and resistance is applied to the flow of liquid from the pressure side chamber L2 to the extending side chamber L1 by the pressure side valve 21 and the main valve body 2. For this reason, the pressure in the pressure side chamber L2 increases when the shock absorber D contracts, and the shock absorber D exhibits a pressure side damping force that hinders its contraction operation.

[0080] Furthermore, during normal operation, when the amount of current supplied to the solenoid S1 is controlled, the greater the thrust of the solenoid S1 by increasing the amount of current supplied to the solenoid S1, the greater the downward (closing) force acting on the second valve body 2B. Therefore, the greater the thrust of the solenoid S1 by increasing the amount of current supplied to the solenoid S1, the higher the valve-opening pressure of the second valve body 2B in the main valve body 2, and the greater the generated compression-side damping force. Thus, during normal operation, the solenoid S1 adjusts the force that pushes the second valve body 2B downward via the spool 3, thereby adjusting the magnitude of the compression-side damping force.

[0081] On the other hand, in the event of a failure where the solenoid S1 is de-energized, the biasing force of the spring 9 is transmitted to the second valve body portion 2B via the spool 3. Therefore, the compression side damping force in the event of a failure is also determined according to the specifications of the spring 9. As described above, in the normal state, the biasing force of the spring 9 is not transmitted to the spool 3, so the specifications of the spring 9 can be freely set without considering the compression side damping force in the normal state.

[0082] The following describes the effects of the solenoid S1, the electromagnetic valve V equipped with the solenoid S1, and the shock absorber D equipped with the electromagnetic valve V including the solenoid S1 according to this embodiment.

[0083] The solenoid S1 according to this embodiment includes a coil 4, a first fixed core 5 located at one axial end of the coil 4, a second fixed core 6 located at the other axial end of the coil 4 with a gap therebetween, a first movable core 7 located between the first fixed core 5 and the second fixed core 6 and attracted to the first fixed core 5 when current is passed through the coil 4, a second movable core 8 located between the first fixed core 5 and the second fixed core 6 and attracted to the second fixed core 6 when current is passed through the coil 4, a spring 9 that biases the first movable core 7 toward the second fixed core 6, and a leaf spring (restricting portion) 90 that restricts movement of the first movable core 7 toward the second fixed core 6 relative to the second movable core 8. Movement of the first movable core 7 relative to the first fixed core 5 and the second fixed core 6 in a direction perpendicular to the axial direction of the coil 4 is restricted.

[0084] According to the above configuration, when the solenoid S1 is de-energized, the first movable iron core 7 is subjected to the biasing force of the spring 9 and moves toward the second fixed iron core 6. When the movement of the first movable iron core 7 toward the second fixed iron core 6 with respect to the second movable iron core 8 is restricted by the leaf spring 90, the first movable iron core 7 and the second movable iron core 8 move integrally toward the second fixed iron core 6. Therefore, when the solenoid S1 is de-energized, the biasing force of the spring 9 is transmitted to the second movable iron core 8 via the first movable iron core 7 and the leaf spring 90.

[0085] On the other hand, when the first movable iron core 7 is attracted by the first fixed iron core 5 and moves in the attracting direction when the solenoid S1 is energized, the spring 9 is compressed by the first movable iron core 7, and the biasing force of the spring 9 is not transmitted to the second movable iron core 8. Further, when the solenoid S1 is energized, the second movable iron core 8 is attracted by the second fixed iron core 6, and the force for attracting the second movable iron core 8 to the second fixed iron core 6 increases as the amount of current supplied to the solenoid S1 increases.

[0086] Therefore, when the force for attracting the second movable iron core 8 when the solenoid S1 is energized is applied as a thrust to an object such as the spool 3, the thrust applied to the object increases as the amount of current supplied to the solenoid S1 increases, and the thrust applied to the object can be decreased as the amount of current supplied to the solenoid S1 decreases. Furthermore, when de-energized, the biasing force of the spring 9 acts on the object via the first movable iron core 7, the leaf spring (restricting portion) 90, and the second movable iron core 8. Since the direction of the biasing force of the spring 9 is the same as the direction of the force for attracting the second movable iron core 8 when the solenoid S1 is energized, according to the above configuration, the object can be biased in the same direction as when energized even when the solenoid S1 is de-energized.

[0087] Furthermore, according to the above configuration, as described above, when the first movable core 7 moves toward the first fixed core 5 against the biasing force of the spring 9 when the solenoid S1 is energized, the biasing force of the spring 9 is no longer transmitted to the second movable core 8, and therefore is no longer transmitted to the spool (target object) 3. Therefore, the thrust of the solenoid S1 when energized and the biasing force applied to the target object by the spring 9 when not energized can be freely set independently. Note that, although the spring 9 is a coil spring in this embodiment, it may be a spring other than a coil spring, such as a disc spring.

[0088] Furthermore, the first movable core 7 of the solenoid S1 of this embodiment is restricted from moving relative to the first fixed core 5 and the second fixed core 6 in a direction perpendicular to the axial direction of the coil 4 (the direction along the center line X of the coil 4). In other words, the first movable core 7 does not move in the radial direction of the coil 4 relative to the first fixed core 5 and the second fixed core 6. This prevents the first movable core 7, which is shifted radially, from interfering with the movement of the second movable core 8, ensuring smooth up and down movement of the second movable core 8. As a result, as described above, when the force attracting the second movable core 8 is applied to an object as thrust, hysteresis is suppressed in the thrust characteristics relative to the amount of current supplied to the solenoid S1, making it easier to control the thrust.

[0089] The solenoid S1 according to this embodiment also includes an annular filler ring 41 interposed between the first stationary core 5 and the second stationary core 6. The second movable core 8 is cylindrical with a bottom, and has an outer bottom 8a and an outer tubular portion 8b standing on the outer peripheral edge of the outer bottom 8a. The outer bottom 8a is inserted into the filler ring 41 so as to be movable in the axial direction toward the second stationary core 6. The first movable core 7 is also cylindrical with a bottom, and has an inner bottom 7a and an inner tubular portion 7b standing on the outer peripheral edge of the inner bottom 7a and having an outer diameter smaller than the inner diameter of the outer tubular portion 8b. The inner bottom 7a is inserted into the outer tubular portion 8b of the second movable core 8 so as to be movable in the axial direction toward the second stationary core 6. One end of the spring 9 is inserted into the inner cylindrical portion 7b of the first movable core 7, and is interposed between the inner bottom portion 7a and the first fixed core 5.

[0090] According to the above configuration, when the coil 4 is excited, the magnetic path passes through the first fixed core 5, the first movable core 7, the second movable core 8, and the second fixed core 6, attracting the first movable core 7 to the first fixed core 5 and attracting the second movable core 8 to the second fixed core 6. Furthermore, since the first movable core 7 and the second movable core 8 can be miniaturized while securing a housing space for the spring 9 inside the first movable core 7, the solenoid S1 can be made smaller.

[0091] Also, according to the above configuration, when the first movable core 7 moves toward the second fixed core 6 side, the inner bottom 7a of the first movable core 7 approaches the outer bottom 8a of the second movable core 8. Therefore, if a leaf spring (restricting portion) 90 is arranged so as to be able to restrict the movement in the approaching direction, the movement of the first movable core 7 toward the second fixed core 6 side with respect to the second movable core 8 can be restricted. And to arrange the leaf spring 90 in that way, for example, the leaf spring 90 may be arranged between the inner bottom 7a and the outer bottom 8a as in the present embodiment, and this is easy to do. That is, according to the above configuration, the leaf spring (restricting portion) 90 can be easily arranged.

[0092] Furthermore, in the solenoid S1, the outer cylindrical portion 8b of the second movable core 8 is located between the inner cylindrical portion 7b of the first movable core 7 and the filler ring 41. However, as described above, the first movable core 7 is restricted from moving in the radial direction (the direction orthogonal to the axial direction of the coil 4) with respect to the first fixed core 5 and the second fixed core 6. Also, the filler ring 41 is interposed between the first fixed core 5 and the second fixed core 6 and is fixedly provided with respect to them. Therefore, according to the solenoid S1, when the first movable core 7 is attracted to the first fixed core 5, it does not shift radially with respect to the filler ring 41. Thus, according to the solenoid S1, it is possible to prevent the outer cylindrical portion 8b of the second movable core 8 from being sandwiched between the first movable core 7 that has shifted radially and the filler ring 41, increasing the sliding resistance during its movement and thereby preventing the smooth vertical movement of the second movable core 8.

[0093] Further, the first movable iron core 7 of the solenoid S1 according to the present embodiment is located on the outer periphery of the tip of the inner cylinder portion 7b that protrudes outside the outer cylinder portion 8b of the second movable iron core 8 and has a guide portion 7c that slidably contacts the inner periphery of the filler ring 41. In this case, the sliding gap formed between the filler ring 41 and the guide portion 7c is very narrow and narrower than the gap formed between the outer cylinder portion 8b and the inner cylinder portion 7b. In other words, the difference between the inner diameter of the filler ring 41 and the outer diameter of the guide portion 7c is smaller than the difference between the inner diameter of the outer cylinder portion 8b and the outer diameter of the inner cylinder portion 7b.

[0094] According to the above configuration, by supporting the guide portion 7c of the first movable iron core 7 with the filler ring 41, it is possible to prevent the first movable iron core 7 from shifting in the radial direction (the direction orthogonal to the axial direction of the coil 4) with respect to the first fixed iron core 5 and the second fixed iron core 6, and the configuration for preventing such a shift can be simplified. Further, according to the above configuration, if the axial length of the guide portion 7c fitted to the filler ring 41, that is, the fitting length between the filler ring 41 and the guide portion 7c, is increased, it is possible to prevent the first movable iron core 7 from tilting within the filler ring 41 and interfering with the smooth vertical movement of the second movable iron core 8. Therefore, according to the solenoid S1, it is possible to more reliably prevent the smooth vertical movement of the second movable iron core 8 from being obstructed by the first movable iron core 7.

[0095] However, the configuration for restricting the radial (direction orthogonal to the axial direction of the coil 4) displacement of the first movable iron core 7 with respect to the first fixed iron core 5 and the second fixed iron core 6 is not limited to the above and can be appropriately changed. FIGS. 5 and 6 show modified examples of the configuration for restricting the radial (direction orthogonal to the axial direction of the coil 4) displacement of the first movable iron core 7 with respect to the first fixed iron core 5 and the second fixed iron core 6. Hereinafter, each modified example of the solenoid S1 according to the present embodiment will be specifically described.

[0096] In the first modification example of the solenoid S1 according to the present embodiment, as shown in FIG. 5, a recess 5a that opens toward the first movable core 7 is formed in the first fixed core 5. The first movable core 7 has a guide portion 7e that extends axially from the tip of the inner cylinder portion 7b instead of the guide portion 7c shown in FIG. 3, and the guide portion 7e is slidably inserted into the recess 5a. In this case, the sliding gap formed between the guide portion 7e and the peripheral wall of the recess 5a is very narrow, and the difference between the diameter of the peripheral wall of the recess 5a and the outer diameter of the guide portion 7e is smaller than the difference between the inner diameter of the outer cylinder portion 8b and the outer diameter of the inner cylinder portion 7b.

[0097] According to the above configuration, the fitting between the recess 5a of the first fixed core 5 and the guide portion 7e can prevent the displacement of the first movable core 7 in the radial direction (the direction orthogonal to the axial direction of the coil 4) with respect to the first fixed core 5 and the second fixed core 6, and the configuration for preventing the displacement can be simplified. Further, according to the above configuration, if the axial length of the guide portion 7e is increased to increase the fitting length, the inclination of the first movable core 7 within the filler ring 41 can be suppressed, and it is possible to more reliably prevent the smooth vertical movement of the second movable core 8 from being hindered by the first movable core 7.

[0098] Subsequently, in the second modification example of the solenoid S1 according to the present embodiment, as shown in FIG. 6, a pipe 50 that protrudes toward the first movable core 7 is attached to the first fixed core 5. The pipe 50 is slidably inserted inside the inner cylinder portion 7b of the first movable core 7. In this case, the sliding gap formed between the pipe 50 and the inner cylinder portion 7b is very narrow, and the difference between the inner diameter of the inner cylinder portion 7b and the outer diameter of the pipe 50 is smaller than the difference between the inner diameter of the outer cylinder portion 8b and the outer diameter of the inner cylinder portion 7b.

[0099] According to the above configuration, the fitting of the pipe 50 provided on the first fixed core 5 into the inner cylindrical portion 7b of the first movable core 7 can prevent radial displacement of the first movable core 7 relative to the first fixed core 5 and the second fixed core 6 (a direction perpendicular to the center line X of the coil 4), and the configuration for preventing this displacement can be simplified. Furthermore, according to the above configuration, by lengthening the axial length of the pipe 50 to increase the fitting length, tilt of the first movable core 7 within the filler ring 41 can be suppressed, and the first movable core 7 can be more reliably prevented from interfering with the smooth up and down movement of the second movable core 8.

[0100] Furthermore, the solenoid S1 according to this embodiment constitutes the solenoid valve V together with a spool (valve element) 3 that opens and closes the pressure control passage p2. When current is applied to the coil 4, the solenoid S1 applies a force to the spool (valve element) 3 that attracts the second movable iron core 8 toward the second fixed iron core 6, causing the spool (valve element) 3 to close the pressure control passage p2. This allows the valve opening pressure of the solenoid valve V to be adjusted by changing the amount of current supplied to the solenoid S1, and the pressure upstream of the solenoid valve V can be set to the valve opening pressure of the solenoid valve V.

[0101] Furthermore, as described above, in the solenoid S1 of this embodiment, the greater the amount of current supplied when energized, the greater the thrust applied to the object. As a result, in the solenoid valve V equipped with the solenoid S1 of this embodiment, the greater the amount of current supplied to the solenoid S1, the higher the valve-opening pressure of the spool 3. In addition, as described above, in the solenoid S1 of this embodiment, even when de-energized, the spring 9 can urge the object in the same direction as the thrust when energized. As a result, in the solenoid valve V equipped with the solenoid S1 of this embodiment, the valve-opening pressure when de-energized can be determined according to the specifications of the spring 9.

[0102] Furthermore, a solenoid valve V including the solenoid S1 of this embodiment is provided in a shock absorber D. In addition to the solenoid valve V, this shock absorber D also includes a cylinder 1, a piston rod 11 inserted into the cylinder 1 so as to be axially movable, a main passage M through which liquid flows when the cylinder 1 and the piston rod 11 move relative to each other in the axial direction, a main valve element 2 that opens and closes this main passage M, a pressure introduction passage p1 that has a throttle O provided midway and that reduces and introduces pressure in the main passage M upstream of the main valve element 2 to the back surface of the main valve element 2, and a pressure control passage p2 that is connected to the pressure introduction passage p1 downstream of the throttle O and in which the solenoid valve V is provided.

[0103] According to the above configuration, when the cylinder 1 and the piston rod 11 move relative to each other in the axial direction, the main valve element 2 applies resistance to the flow of liquid passing through the main passage M, generating a damping force due to this resistance. Furthermore, because the back pressure of the main valve element 2 is set to the valve opening pressure of the solenoid valve V, the back pressure of the main valve element 2 can be adjusted by changing the amount of current supplied to the solenoid S1. The higher the back pressure of the main valve element 2, the more difficult it becomes for the first valve element portion 2A of the main valve element 2 to open, and the greater the generated extension-side damping force. Therefore, according to the above configuration, the generated extension-side damping force can be adjusted by changing the amount of current supplied to the solenoid S1.

[0104] Furthermore, as described above, in the solenoid valve V including the solenoid S1 of this embodiment, the greater the amount of current supplied to the solenoid S1, the higher the valve opening pressure of the solenoid valve V. As a result, in the shock absorber D equipped with the solenoid valve V including the solenoid S1 of this embodiment, the greater the amount of current supplied to the solenoid S1, the higher the back pressure of the main valve element 2, and the greater the generated extension-side damping force.

[0105] In other words, in the shock absorber D, the damping force on the extension side that is generated when the amount of current supplied to the solenoid S1 is small can be reduced, so when the shock absorber D is used in a vehicle suspension, power consumption during normal driving can be reduced. This also makes it possible to suppress heat generation in the solenoid S1 and reduce temperature changes in the shock absorber D, thereby reducing changes in the damping force characteristics (damping force characteristics relative to piston speed) that are caused by changes in liquid temperature.

[0106] In addition, as described above, in the solenoid valve V including the solenoid S1 of this embodiment, the valve opening pressure when not energized is determined according to the specifications of the spring 9. For this reason, in the shock absorber D equipped with the solenoid valve V including the solenoid S1 of this embodiment, the back pressure of the main valve element 2 can be increased even when the solenoid S1 is not energized. As a result, in the shock absorber D, it is possible to prevent a shortage of damping force on the extension side even in a failure state in which the solenoid S1 is de-energized. Furthermore, in the shock absorber D, it is sufficient to provide the pressure control passage p2 as a passage connected to the back pressure chamber L4 and setting the back pressure of the main valve element 2. This eliminates the need to switch the passage connected to the back pressure chamber L4 depending on whether the solenoid S1 is energized or not, thereby preventing the structure of the shock absorber D from becoming complicated and reducing costs.

[0107] In this embodiment, the back pressure of the main valve element 2 is controlled by the solenoid valve V only when the shock absorber D is extended, and when it is retracted, the thrust of the solenoid S1 in the solenoid valve V is applied directly to the main valve element 2 in the closing direction. However, it is of course possible to control the back pressure of the main valve element by the solenoid valve V when the shock absorber D is retracted.

[0108] Furthermore, the rod that moves in and out of the cylinder 1 does not necessarily have to be a piston rod with a piston attached, and the position of the main valve element whose back pressure is controlled by the solenoid valve V is not limited to the piston portion. For example, if the shock absorber is equipped with a reservoir as described above, the main valve element may be provided in a passage that connects the extension-side chamber or the compression-side chamber to the reservoir as the main passage, and the back pressure of the main valve element may be controlled by the solenoid valve V. Furthermore, if the shock absorber is a uniflow type in which liquid circulates in one direction in the order of the extension-side chamber, reservoir, and compression-side chamber during expansion and contraction, the main valve element may be provided in that circulation passage as the main passage, and the back pressure of the main valve element may be controlled by the solenoid valve V.

[0109] <Second embodiment> Next, the solenoid S2 according to the second embodiment of the present invention shown in FIG. 7 will be described. Similar to the solenoid S1 of the first embodiment, the solenoid S2 according to the present embodiment is used for a solenoid valve, and the solenoid S1 of the first embodiment shown in FIG. 2 can be directly replaced with the solenoid S2 of the present embodiment. Further, the basic structure of the solenoid S2 according to the present embodiment is the same as that of the solenoid S1 according to the first embodiment, and the same reference numerals are given to the common configurations and the detailed description thereof is omitted.

[0110] A major difference between the solenoid S2 of the present embodiment and the solenoid S1 according to the first embodiment is that the arrangements of the first movable iron core and the second movable iron core are reversed inside and outside. More specifically, in the present embodiment, the first movable iron core 7A has an inner cylinder portion 7f and an outer cylinder portion 7g that are arranged in a double inside and outside manner, a connecting portion 7h that connects one axial end of these, and an inner bottom portion 7i located at the other end of the inner cylinder portion 7f. The outer cylinder portion 7g is slidably contacted with the inner circumference of the filler ring 41 with the inner bottom portion 7i facing downward (toward the second fixed iron core 6 side). On the other hand, the second movable iron core 8A has a bottomed cylindrical shape and has an outer bottom portion 8d and an intermediate cylinder portion 8e that stands up on the outer peripheral edge of the outer bottom portion 8d. The intermediate cylinder portion 8e is slidably contacted with the inner circumference of the outer cylinder portion 7g of the first movable iron core 7A with the outer bottom portion 8d facing downward (toward the second fixed iron core 6 side).

[0111] A communication hole 7j that penetrates the wall thickness is formed in the inner bottom portion 7i of the first movable iron core 7A, and liquid can move through the communication hole 7j with relatively little resistance. As a result, liquid is not trapped above the first movable iron core 7A (on the side of the first fixed iron core 5), and smooth vertical movement of the first movable iron core 7A is ensured. A spring 9 is inserted inside the inner cylinder portion 7f of the first movable iron core 7A. Also in the present embodiment, the spring 9 is a coil spring, and one end of the spring 9 abuts against the inner bottom portion 7i. On the other hand, the other end of the spring 9 is supported by the first fixed iron core 5, and the spring 9 biases the first movable iron core 7A downward.

[0112] Also, on the outer bottom 8d of the second movable iron core 8A, a communication hole 8f penetrating its wall thickness is formed, and liquid can move through the communication hole 8f with relatively little resistance. Further, the inner diameter of the intermediate cylinder portion 8e of the second movable iron core 8A is larger than the outer diameter of the inner cylinder portion 7f of the first movable iron core 7A, creating an annular gap between the intermediate cylinder portion 8e and the inner cylinder portion 7f. For this reason, the space L8 formed above the tip of the intermediate cylinder portion 8e (on the side of the first fixed iron core 5) and the space L9 formed between the outer bottom 8d and the inner bottom 7a are continuous. And since the communication hole 8f communicates with the continuous space, it is possible to suppress the generation of a damping force that traps liquid in the space and hinders the movement of the second movable iron core 8A.

[0113] Furthermore, in the present embodiment, since the first movable iron core 7A moves up and down (in the axial direction) while being supported by the filler ring 41 on its outer cylinder portion 7g, it does not become eccentric with respect to the filler ring 41 during the movement. The filler ring 41 is sandwiched between the first fixed iron core 5 and the second fixed iron core 6 and is fixedly provided with respect to them, so the filler ring 41 prevents the first movable iron core 7A from shifting in the direction orthogonal to the center line of the coil (radial direction).

[0114] Also, the second movable iron core 8A moves up and down (in the axial direction) while being supported by the outer cylinder portion 7g of the first movable iron core 7A on its intermediate cylinder portion 8e. Thus, in the solenoid S2 of the present embodiment, the second movable iron core 8A is inserted further inside the first movable iron core 7A inserted into the filler ring 41. Thereby, it is possible to prevent both the first movable iron core 7A from shifting in the radial direction when it is attracted to the first fixed iron core 5 and the second movable iron core 8A from being pinched between the radially shifted first movable iron core 7A and the filler ring 41, and there is no concern that the second movable iron core 8A will be pinched between the radially shifted first movable iron core 7A and the filler ring 41 and the sliding resistance during its movement will increase.

[0115] In addition, in the present embodiment, as shown in FIG. 7(b), a protrusion 7k protruding toward the center side is provided on the inner periphery of the tip of the outer cylinder portion 7g of the first movable core 7A, and a fluororesin sheet 70 is held on the inner periphery of the outer cylinder portion 7g by this protrusion 7k. As a result, the slidability between the intermediate cylinder portion 8e of the second movable core 8A and the outer cylinder portion 7g of the first movable core 7A is improved. Note that the material of the sheet 70 is not limited to fluororesin and can be appropriately changed as long as it has good slidability. Furthermore, the sheet 70 may be omitted and the intermediate cylinder portion 8e may be directly slidably contacted with the inner periphery of the outer cylinder portion 7g.

[0116] Subsequently, also in the present embodiment, leaf springs 90 and 91 that function as regulating portions are disposed above and below the outer bottom portion 8d of the second movable core 8A. More specifically, the upper leaf spring 90, which is the first regulating portion, is located between the outer bottom portion 8d of the second movable core 8A and the inner bottom portion 7i of the first movable core 7A that faces it vertically, and the lower leaf spring 91, which is the second regulating portion, is located between the outer bottom portion 8d of the second movable core 8A and the second fixed core 6 that faces it vertically.

[0117] When the first movable core 7A moves downward with respect to the second movable core 8A, the inner bottom portion 7i of the first movable core 7A abuts against the leaf spring 90. Then, the downward movement of the first movable core 7A with respect to the second movable core 8A is restricted, and thereafter, the first movable core 7A moves downward integrally with the second movable core 8A. Also, when the second movable core 8A moves downward, the outer bottom portion 8d of the second movable core 8A abuts against the leaf spring 91 and compresses it, and it no longer moves downward.

[0118] Furthermore, a through-hole is formed in the center of the second fixed core 6, and the shaft 3a of the spool 3 is movably inserted through this through-hole. The tip of the shaft 3a abuts against the outer bottom 8d of the second movable core 8A. As a result, when the coil is de-energized, the first movable core 7A moves downward due to the biasing force of the spring 9 and abuts against the second movable core 8A via the leaf spring 90, and the spool 3 is subjected to a downward force due to the biasing force of the spring 9. In contrast, when the coil is energized to attract the first movable core 7A to the first fixed core 5 and the second movable core 8A to the second fixed core 6, the spring 9 is compressed by the first movable core 7A and the biasing force is no longer transmitted to the spool 3, but the spool 3 is subjected to a downward force due to the force attracting the second movable core 8A.

[0119] Furthermore, the leaf spring 90, which is the first restricting portion, restricts the approach between the inner bottom portion 7i of the first movable core 7A and the outer bottom portion 8d of the second movable core 8A, which faces it in the vertical direction (axial direction), thereby preventing the first movable core 7A and the second movable core 8A from sticking together when current is applied to the coil. Similarly, the leaf spring 91, which is the second restricting portion, restricts the approach between the outer bottom portion 8d of the second movable core 8A and the second fixed core 6, which faces it in the vertical direction (axial direction), thereby preventing the second movable core 8A from sticking to the second fixed core 6 when current is applied to the coil. Note that the first and second restricting portions are not limited to the leaf springs 90 and 91, respectively, and can be modified as in the first embodiment.

[0120] On the other hand, no restricting portion is provided between the first fixed core 5 and the first movable core 7A, and the first movable core 7A is attracted to the first fixed core 5 when current is applied to the coil. In this way, when the first movable core 7A is attracted to the first fixed core 5 when current is applied to the coil, the first movable core 7A compresses the spring 9, and the posture of the first movable core 7A can be stably maintained so that the biasing force of this spring 9 is not transmitted to the second movable core 8A side. However, it is not necessary for the first movable core 7A to be attracted to the first fixed core 5 when current is applied to the coil.

[0121] The relationship between the amount of current supplied to the solenoid S2 according to this embodiment and the force that the solenoid S2 applies to the spool (object) 3 is as shown in Fig. 4, similar to that of the solenoid S1 according to the first embodiment. The operation of the shock absorber equipped with the electromagnetic valve including the solenoid S2 according to this embodiment is similar to the operation of the shock absorber D equipped with the electromagnetic valve V including the solenoid S1 according to the first embodiment.

[0122] The following describes the effects of the solenoid S2 according to this embodiment. It goes without saying that the same functions and effects are achieved as with the solenoid S1 of the first embodiment, and detailed descriptions thereof will be omitted here. Furthermore, the effects of the solenoid valve including the solenoid S2 according to this embodiment and the shock absorber including the solenoid valve including the solenoid S2 are similar to the effects of the solenoid S1 of the first embodiment, the solenoid valve V including the solenoid S1, and the shock absorber D including the solenoid valve V including the solenoid S1, and therefore detailed descriptions thereof will be omitted here.

[0123] The solenoid S2 according to this embodiment includes a coil, a first fixed core 5 located at one axial end of the coil, a second fixed core 6 located at the other axial end of the coil with a gap between it and the first fixed core 5, a first movable core 7A located between the first fixed core 5 and the second fixed core 6 and attracted to the first fixed core 5 when current is passed through the coil, a second movable core 8A located between the first fixed core 5 and the second fixed core 6 and attracted to the second fixed core 6 when current is passed through the coil, a spring 9 that biases the first movable core 7A toward the second fixed core 6, and a leaf spring (restricting portion) 90 that restricts movement of the first movable core 7A toward the second fixed core 6 relative to the second movable core 8A. Movement of the first movable core 7A relative to the first fixed core 5 and the second fixed core 6 in a direction perpendicular to the axial direction of the coil is restricted.

[0124] According to the above configuration, when the solenoid S2 is de-energized, the first movable iron core 7A is urged by the biasing force of the spring 9 and moves toward the second fixed iron core 6. When the movement of the first movable iron core 7A toward the second fixed iron core 6 with respect to the second movable iron core 8A is restricted by the leaf spring 90, the first movable iron core 7A and the second movable iron core 8A move together toward the second fixed iron core 6. Therefore, when the solenoid S2 is de-energized, the biasing force of the spring 9 is transmitted to the second movable iron core 8A via the first movable iron core 7A and the leaf spring 90.

[0125] On the other hand, when the solenoid S2 is energized and the first movable iron core 7A is attracted by the first fixed iron core 5 and moves in the attracting direction, the spring 9 is compressed by the first movable iron core 7A, and the biasing force of the spring 9 is not transmitted to the second movable iron core 8A. Further, when the solenoid S2 is energized, the second movable iron core 8A is attracted by the second fixed iron core 6, and the force for attracting the second movable iron core 8A to the second fixed iron core 6 increases as the amount of current supplied to the solenoid S2 increases.

[0126] Therefore, when the force for attracting the second movable iron core 8A when the solenoid S2 is energized is applied as a thrust to an object such as the spool 3, the thrust applied to the object increases as the amount of current supplied to the solenoid S2 increases, and the thrust applied to the object can be decreased as the amount of current supplied to the solenoid S2 decreases. Further, when de-energized, the biasing force of the spring 9 acts on the object via the first movable iron core 7A, the leaf spring (restricting portion) 90, and the second movable iron core 8A. Since the direction of the biasing force of the spring 9 is the same as the direction of the force for attracting the second movable iron core 8A when the solenoid S2 is energized, according to the above configuration, the object can be biased in the same direction as when energized even when the solenoid S2 is de-energized.

[0127] Furthermore, according to the above configuration, as described above, when the first movable core 7A moves toward the first fixed core 5 against the biasing force of the spring 9 when the solenoid S2 is energized, the biasing force of the spring 9 is no longer transmitted to the second movable core 8A, and therefore is no longer transmitted to the spool (target object) 3. Therefore, the thrust of the solenoid S2 when energized and the biasing force applied to the target object by the spring 9 when not energized can be freely set independently. Note that, although the spring 9 is a coil spring in this embodiment, it may be a spring other than a coil spring, such as a disc spring.

[0128] Furthermore, the first movable core 7A of the solenoid S2 in this embodiment is restricted from moving in a direction perpendicular to the axial direction of the coil (the direction along the center line X of the coil) relative to the first fixed core 5 and the second fixed core 6. In other words, the first movable core 7A does not move in the radial direction of the coil relative to the first fixed core 5 and the second fixed core 6. This prevents the first movable core 7A, which is shifted radially, from interfering with the movement of the second movable core 8A, ensuring smooth up and down movement of the second movable core 8A. As a result, as described above, when the force attracting the second movable core 8A is applied to an object as thrust, hysteresis is suppressed in the thrust characteristics relative to the amount of current supplied to the solenoid S2, making it easier to control the thrust.

[0129] The solenoid S2 according to this embodiment also includes an annular filler ring 41 interposed between the first stationary core 5 and the second stationary core 6. The first movable core 7A has an inner cylindrical portion 7f and an outer cylindrical portion 7g arranged in a double layer, an inner and outer cylindrical portion 7h connecting one axial end of the inner cylindrical portion 7f and the outer cylindrical portion 7g, and an inner bottom portion 7i located at the other end of the inner cylindrical portion 7f, with the inner bottom portion 7i slidably inserted inside the filler ring 41 toward the second stationary core 6. Meanwhile, the second movable core 8A has a bottomed cylindrical shape and includes an outer bottom portion 8d and an intermediate cylindrical portion 8e standing on the outer peripheral edge of the outer bottom portion 8d and having an inner diameter larger than the outer diameter of the inner cylindrical portion 7f of the first movable core 7A, with the outer bottom portion 8d facing toward the second stationary core 6, and the intermediate cylindrical portion 8e slidably inserted inside the outer cylindrical portion 7g of the first movable core 7A. Furthermore, one end of the spring 9 is inserted into the inner cylindrical portion 7f of the first movable core 7A, and is interposed between the inner bottom portion 7i and the first fixed core 5.

[0130] According to the above configuration, when the coil is excited, a magnetic path passes through the first fixed core 5, the first movable core 7A, the second movable core 8A, and the second fixed core 6, so that the first movable core 7A is attracted to the first fixed core 5 and the second movable core 8A is attracted to the second fixed core 6. Furthermore, a space for accommodating the spring 9 can be secured inside the first movable core 7A.

[0131] Furthermore, with the above configuration, when the first movable core 7A moves toward the second fixed core 6, the inner bottom 7i of the first movable core 7A approaches the outer bottom 8d of the second movable core 8A. Therefore, if a leaf spring (restriction portion) 90 is arranged to restrict these movements in the approaching direction, movement of the first movable core 7A toward the second fixed core 6 relative to the second movable core 8A can be restricted. Arranging the leaf spring 90 in this manner can be easily achieved by, for example, arranging the leaf spring 90 between the inner bottom 7i of the first movable core 7A and the outer bottom 8d of the second movable core 8A, as in this embodiment. In other words, with the above configuration, the leaf spring (restriction portion) 90 can be easily arranged.

[0132] Furthermore, in the solenoid S2, an intermediate cylinder portion 8e of a second movable iron core 8A is slidably inserted inside an outer cylinder portion 7g of a first movable iron core 7A that is slidably inserted into a filler ring 41. In this way, since the second movable iron core 8A is inserted further inside the first movable iron core 7A inserted into the filler ring 41, when the first movable iron core 7A is attracted to the first fixed iron core 5, it will not shift radially, nor will the second movable iron core 8A be pinched between the radially shifted first movable iron core 7A and the filler ring 41. Therefore, according to the above configuration, it is possible to prevent the second movable iron core 8A from being pinched between the radially shifted first movable iron core 7A and the filler ring 41, which would increase the sliding resistance during its movement and thereby prevent the smooth up and down movement of the second movable iron core 8A.

[0133] As described above, the preferred embodiments of the present invention have been described in detail. However, modifications, deformations, and changes are possible without departing from the scope of the claims.

Explanation of Reference Numerals

[0134] D ··· Damper, M ··· Main passage, O ··· Throttle, p1 ··· Pressure introduction passage, p2 ··· Pressure control passage, S1, S2 ··· Solenoid, V ··· Solenoid valve, 1 ··· Cylinder, 2 ··· Main valve body, 3 ··· Spool (valve body), 4 ··· Coil, 5 ··· First fixed iron core, 5a ··· Recess, 6 ··· Second fixed iron core, 7, 7A ··· First movable iron core, 7a, 7i ··· Inner bottom, 7b, 7f ··· Inner cylinder portion, 7c, 7e ··· Guide portion, 7g ··· Outer cylinder portion, 7h ··· Connecting portion, 8, 8A ··· Second movable iron core, 8a, 8d ··· Outer bottom, 8b ··· Outer cylinder portion, 8e ··· Intermediate cylinder portion, 9 ··· Spring, 11 ··· Piston rod (rod), 41 ··· Filler ring, 50 ··· Pipe, 90 ··· Leaf spring (restriction portion)

Claims

1. A coil, a first fixed core located on one axial end side of the coil, a second fixed core located on the other axial end side of the coil with a gap from the first fixed core, a first movable core disposed between the first fixed core and the second fixed core and attracted to the first fixed core by energizing the coil, a second movable core disposed between the first fixed core and the second fixed core and attracted to the second fixed core by energizing the coil, a spring for biasing the first movable core toward the second fixed core side, and the first movable core has an inner cylindrical portion and an outer cylindrical portion disposed inside and outside in a double layer, a connecting portion connecting one axial end of the inner cylindrical portion and the outer cylindrical portion, and an inner bottom portion located at the other end of the inner cylindrical portion, the second movable core is in a bottomed cylindrical shape and has an outer bottom portion and an intermediate cylindrical portion standing on the outer peripheral edge of the outer bottom portion and having an inner diameter larger than the outer diameter of the inner cylindrical portion, and the outer bottom portion is inserted slidably inside the outer cylindrical portion with the intermediate cylindrical portion facing the second fixed core side, one end side of the spring is inserted inside the inner cylindrical portion and is interposed between the inner bottom portion and the first fixed core A solenoid characterized by the above.

2. A solenoid valve provided in the middle of a pressure control passage and comprising the solenoid according to claim 1, comprising a valve body for opening and closing the pressure control passage, when the solenoid is energized, the force for attracting the second movable core toward the second fixed core is applied to the valve body in the direction of closing the pressure control passage A solenoid valve characterized by the above.

3. A shock absorber comprising the solenoid valve according to claim 2, a cylinder, a rod inserted movably in the axial direction inside the cylinder, a main passage through which a liquid flows when the cylinder and the rod move relative to each other in the axial direction, a main valve body for opening and closing the main passage, a pressure introduction passage provided with a throttle in the middle and guiding the pressure on the upstream side of the main valve body of the main passage to the back surface of the main valve body to reduce the pressure, and a pressure control passage to which the solenoid valve is provided and which is connected downstream of the throttle of the pressure introduction passage A shock absorber characterized by the above.

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