Solenoids, solenoid valves, and shock absorbers

Abstract

To provide a solenoid, a solenoid valve, and a buffer that can reduce solenoid thrust to be provided to an object when the amount of current supplied to the solenoid is small, and can urge the object in the same direction as thrust at energization even when the solenoid is not energized.SOLUTION: A solenoid S1 includes a first fixed iron core 5 and a second fixed iron core 6 that are located on one end side and the other end side of a coil in the axial direction, a first movable iron core 7 and a second movable iron core 8 that are located between the first fixed iron core and the second fixed iron core and are attracted to the first fixed iron core 5 and the second fixed iron core 6, respectively by energization to the coil, a spring 9 that urges the first movable iron core 7 to the second fixed iron core 6, and a plate spring 90 that regulates 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. The movement of first movable iron core 7 is regulated in the direction perpendicular to the axial direction of a coil 4 with respect to the first fixed iron core 5 and the second fixed iron core 6.SELECTED DRAWING: Figure 3

Description

[Technical field]

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

[0002] Conventionally, some solenoids include a coil and a movable core that is attracted to one side of the axial direction of the coil by magnetic flux when a magnetic field is generated by energizing the coil, and the force that attracts the movable core is applied to another member (target object) as a thrust, and the thrust can be changed according to the amount of current. Such solenoids are used, for example, in electromagnetic valves.

[0003] Among these solenoid valves, there are those that are provided midway through the pressure control passage and, in addition to the solenoid, are a valve body that opens and closes the pressure control passage and a spring that biases the valve body in the opening direction, and the solenoid applies a thrust to the valve body in the closing direction. With this solenoid valve, the more the amount of current supplied to the solenoid is increased, the higher the valve opening pressure of the solenoid valve becomes, and the pressure upstream of the solenoid valve can be increased. Such solenoid valves are used, for example, in shock absorbers.

[0004] Some of these shock absorbers are equipped with, in addition to a solenoid valve, a main passage through which liquid flows when the shock absorber expands or contracts, and a main valve body that opens and closes this main passage, and a pressure control passage in which a solenoid valve is provided is connected to a back pressure chamber formed on the back surface of the main valve body.With this shock absorber, the back pressure of the main valve body (pressure in the back pressure chamber) increases as the amount of current supplied to the solenoid is increased to increase the valve opening pressure of the solenoid valve, and the generated damping force can be increased (for example, Patent Document 1). [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2014-173716 A Summary of the Invention [Problem 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 is running on a good road, it is preferable to reduce the damping force generated during normal driving. In a shock absorber equipped with a conventional solenoid-containing electromagnetic valve, the damping force generated can be reduced when the amount of current supplied to the solenoid is reduced, so that power consumption during normal driving can be reduced and electricity can be saved. However, in a conventional shock absorber, if the solenoid is de-energized in a fail state, the solenoid valve is fully open and the back pressure of the main valve body is minimized, resulting in insufficient damping force during a fail state.

[0007] For this reason, the valve element of the solenoid valve provided in the shock absorber described in JP 2014-173716 A has two opening / closing portions that open and close the pressure control passage. One of the opening / closing portions is biased in an opening direction by a spring, and functions as an opening / closing portion during pressure control when a thrust in a closing direction is applied by a solenoid. Meanwhile, the other opening / closing portion closes the downstream side of the portion of the pressure control passage that is opened or closed by the one opening / closing portion when the one opening / closing portion is fully opened by the biasing force of the spring when the solenoid is not energized.

[0008] Furthermore, the shock absorber is provided with a fail passage connected between a portion of the pressure control passage that is opened and closed by one opening / closing portion and a portion that is opened and closed by the other opening / closing portion, with a passive valve provided in the middle. As a result, when the pressure control passage is closed by the other opening / closing portion of the solenoid valve when the solenoid is not 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 valve opening pressure of the passive valve. Therefore, even in conventional shock absorbers, the damping force of the shock absorber is not insufficient in the event of 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 between when the solenoid is energized and when it is 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 between when the solenoid is energized and when it is not energized, but the amount of current supplied to the solenoid must be increased when the generated damping force is reduced, resulting in high 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 desired 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 cannot be achieved 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, there are problems such as a complicated structure of the shock absorber and high power consumption during normal vehicle driving.

[0011] Therefore, the present invention has been devised to solve such problems, and to provide a solenoid, solenoid valve, and 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 bias 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] The solenoid that solves the above problem includes a first fixed core and a second fixed core located at one and the other axial ends of a coil, an annular filler ring interposed between the first fixed core and the second fixed core, a first movable core and a second movable core located between the first fixed core and the second fixed core and attracted to the first fixed core and the second fixed core, respectively, when a current is passed through the coil, a spring that urges the first movable core towards the second fixed core, and a restricting portion that restricts movement of the first movable core towards the second fixed core relative to the second movable core, the second movable core being cylindrical with a bottom and having an outer bottom and an outer peripheral edge that is raised from the outer bottom. The first movable core has an outer tubular portion that faces the outer peripheral edge of the inner bottom and is inserted axially movably inside the filler ring with its outer bottom toward the second fixed core, the first movable core is cylindrical with a bottom and has an inner bottom and an inner tubular portion that stands on the outer peripheral edge of the inner bottom and has an outer diameter smaller than the inner diameter of the outer tubular portion, and the inner tubular portion is inserted axially movably inside the outer tubular portion with the inner bottom facing the second fixed core, and one end of a spring is inserted inside the inner tubular portion and interposed between the inner bottom and the first fixed core, and movement of the first movable core in a direction perpendicular to the axial direction of the front coil relative to the first fixed core and the second fixed core is restricted. Furthermore, a solenoid that solves the above problem comprises a coil, a first fixed core located at one end of the coil in the axial direction, a second fixed core located at the other end of the coil in the axial direction with a gap from the first fixed core, a first movable core arranged between the first fixed core and the second fixed core and attracted to the first fixed core when current is passed through the coil, a second movable core arranged between the first fixed core and the second fixed core and attracted to the second fixed core when current is passed through the coil, a spring that urges the first movable core toward the second fixed core, and a regulating part that regulates movement of the first movable core toward the second fixed core relative to the second movable core, wherein the first movable core is regulated in movement in a direction perpendicular to the axial direction of the coil relative to the first fixed core and the second fixed core, and the regulating part is a leaf spring having a ring-shaped seat and a plurality of legs rising from the seat.

[0013] According to the above configuration, when the solenoid is not energized, the first movable core advances toward the second fixed core under 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 by the restricting portion, the biasing force of the spring is transmitted from the first movable core to the second movable core via the restricting portion. 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 not transmitted to the second movable core. Also, 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, if the force attracting the second movable core is applied to the object as a thrust when the solenoid is energized, the thrust applied to the object can be increased by increasing the amount of current supplied to the solenoid, and the thrust applied to the object can be decreased by decreasing the amount of current supplied to the solenoid. Furthermore, when the solenoid is not energized, the biasing force of the spring acts on the object via the first movable core, the restricting portion, 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, according to the above configuration, the object can be biased in the same direction as when the solenoid is energized, even when the solenoid is not energized.

[0015] Furthermore, according to the above configuration, the movement of the first movable iron core in a direction perpendicular to the axial direction of the coil relative to the first fixed iron core and the second fixed iron core, i.e., in the radial direction, is restricted.As a result, the movement of the second movable iron core is not hindered by the first movable iron core shifted radially, and smooth up and down movement of the second movable iron core can be ensured.

[0016] In addition, the solenoid is provided with an annular filler ring interposed between the first fixed core and the second fixed core, the second movable core is cylindrical with a bottom and has an outer bottom and an outer tube portion, the outer bottom being inserted axially movably inside the filler ring toward the second fixed core, the first movable core is cylindrical with a bottom and has an inner bottom and an inner tube portion whose outer diameter is smaller than the inner diameter of the outer tube portion, the inner tube portion being inserted axially movably inside the outer tube portion with the inner bottom facing the second fixed core, and one end of a spring is inserted inside the inner tube portion and interposed between the inner bottom and the first fixed core.

[0017] According to 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.

[0018] In addition, with the above configuration, when the first movable core moves toward the second fixed core, the inner bottom of the first movable core approaches the outer bottom of the second movable core. Therefore, if a restricting portion is disposed to restrict movement in the approaching direction, the restricting portion can restrict movement of the first movable core toward the second fixed core relative to the second movable core, and the restricting portion can be disposed easily.

[0019] Furthermore, according to the above configuration, the outer cylinder of the second movable core is located between the inner cylinder of the first movable core and the filler ring, but as described above, the radial movement of the first movable core relative to the first and second fixed cores is restricted, and the filler ring is fixedly provided relative to the first and second fixed cores. Therefore, when the first movable core moves, the first movable core does not shift radially relative to the filler ring, and the outer cylinder of the second movable core is prevented from being pinched between the first movable core and the filler ring that are radially shifted, which prevents the sliding resistance during the movement from increasing. Furthermore, in the above other solenoid, the restricting portion is a leaf spring having an annular plate-shaped seat and a plurality of legs standing up from the seat, so that a gap is formed between the adjacent legs, and the restricting portion does not hinder the flow of the liquid.

[0020] The first movable core of the solenoid may have a guide portion located on the outer periphery of the tip of the inner cylinder portion protruding out of the outer cylinder portion and in sliding contact with the inner periphery of the filler ring. In this way, it is easy to restrict the movement of the first movable core in a direction perpendicular to the axial direction of the coil relative to the first fixed core and the second fixed core. In addition, by making the guide portion longer in the axial direction, the inclination of the first movable core in the filler ring can be suppressed.

[0021] The first movable core of the solenoid may have a guide portion extending in the axial direction from the tip of the inner cylinder portion, and the guide portion may be slidably inserted into a recess formed in the first fixed core. In this case, it is also easy to restrict the movement of the first movable core in a direction perpendicular to the axial direction of the coil relative to the first fixed core and the second fixed core. In addition, by making the guide portion axially longer, the inclination of the first movable core within the filler ring can be suppressed.

[0022] The solenoid may also include a pipe attached to the first fixed core, and the pipe may be slidably inserted inside the inner cylinder. In this case, it is also easy to restrict the movement of the first movable core relative to the first fixed core and the second fixed core in a direction perpendicular to the axial direction of the coil. In addition, by increasing the fitting length between the pipe and the inner cylinder, the inclination of the first movable core within the filler ring can be suppressed.

[0023] Alternatively, 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 that is generated when the solenoid energizes the coil and attracts the second movable core toward the second fixed core may be applied to the valve body in a direction that closes the pressure control passage. In this way, the 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 to the opening pressure of the solenoid valve.

[0024] Furthermore, as described above, in the solenoid, the greater the amount of current supplied, 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 body in the closing direction, and the higher the valve-opening pressure of the solenoid valve. In addition, as described above, in the solenoid, even when not 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 not energized can be determined according to the specifications of the spring.

[0025] In addition, an electromagnetic valve including the solenoid may be provided in a shock absorber, the shock absorber comprising a cylinder, a rod inserted into the cylinder so as to be axially movable, a main passage through which liquid flows when the cylinder and the rod move axially relative to each other, a main valve body which opens and closes the main passage, a pressure introduction passage having a throttle provided midway and reducing and introducing pressure in the main passage upstream of the main valve body to a back surface of the main valve body, and a pressure control passage connected downstream of the throttle of the pressure introduction passage and in which the solenoid valve is provided.

[0026] In this way, if the main valve body provides resistance to the flow of liquid passing through the main passage when the cylinder and rod move relative to each other in the axial direction, the shock absorber can generate a damping force due to that resistance. Also, 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 becomes for the main valve body to open, and the greater the damping force generated. Therefore, with the above configuration, the generated damping force can be adjusted by changing the amount of current supplied to the solenoid.

[0027] Furthermore, as described above, in the above solenoid valve, the greater the amount of current supplied to the solenoid, the higher the valve opening pressure of the solenoid valve can be, so in the above shock absorber, the greater the amount of current supplied to the solenoid, the higher the back pressure of the main valve body can be, and the greater the damping force generated. In other words, in the above shock absorber, the damping force generated can be reduced when the amount of current supplied to the solenoid is small, so when the above shock absorber is used as a vehicle suspension, power consumption during normal driving can be reduced. This also suppresses heat generation in the solenoid and reduces temperature changes in the shock absorber, so that changes in the damping force characteristics (damping force characteristics relative to piston speed) caused by changes in liquid temperature can be reduced.

[0028] In addition, as described above, in the solenoid valve, the valve opening pressure when de-energized is determined according to the specifications of the spring, so in the shock absorber, the back pressure of the main valve body can be increased even when the solenoid is de-energized. This makes it possible to prevent the shock absorber from having a shortage of damping force in the event of a failure. Furthermore, in the shock absorber, it is sufficient to provide a pressure control passage as a passage for setting the back pressure of the main valve body, and there is no need to switch the passage for setting the back pressure depending on whether the solenoid is energized or de-energized, which prevents the shock absorber structure from becoming complicated and reduces costs. Effect of the Invention

[0029] According to the solenoid, electromagnetic valve, and shock absorber of the present invention, the thrust force of the solenoid applied to an object can be reduced when the amount of current supplied to the solenoid is small, and the object can be biased in the same direction as the thrust when the solenoid is energized even when the solenoid is not energized. [Brief description of the drawings]

[0030] [Figure 1] 1 is a vertical sectional view of a shock absorber provided with an electromagnetic valve including a solenoid according to a first embodiment of the present invention; [Diagram 2] 1 is an enlarged longitudinal sectional view showing a solenoid valve including a solenoid according to a first embodiment of the present invention; [Diagram 3] FIG. 2 is a partially enlarged cross-sectional view of a solenoid according to the first embodiment of the present invention. [Figure 4] 5 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. [Diagram 5] FIG. 2 is a partially enlarged cross-sectional view of a first modified example of the solenoid according to the first embodiment of the present invention. [Figure 6] FIG. 11 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] 1A is a partially enlarged cross-sectional view of a solenoid according to a second embodiment of the present invention, and FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0031] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an embodiment 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 (portions).

[0032] 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 purpose of use of the solenoid, the solenoid valve including the solenoid, and the shock absorber including the solenoid valve according to the present invention is not limited to the above and can be changed as appropriate.

[0033] <First embodiment> 1, a shock absorber D equipped with an electromagnetic valve V including a solenoid according to a 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 body and the axle of a vehicle, and the piston rod 11 is connected to the other. In this manner, the shock absorber D is interposed between the body and the axle.

[0034] When the vehicle runs on an uneven road surface and the wheels vibrate up and down, the piston rod 11 moves in and out of the cylinder 1, the shock absorber D expands and contracts, and the piston 10 moves up and down (axially) within the cylinder 1 in Fig. 1. Note that, although Fig. 1 shows a state in which the piston rod 11 protrudes upward from the cylinder 1, the shock absorber D may be attached to the vehicle in any orientation.

[0035] Next, an annular head member 12, into which a piston rod 11 can be inserted, is attached to one axial end of the cylinder 1. This head member 12 slidably supports the piston rod 11 and closes one end of the cylinder 1. Meanwhile, 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 liquid and gas are sealed inside the cylinder 1.

[0036] More specifically, a free piston 14 is slidably inserted into the cylinder 1 on the opposite side of 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. Meanwhile, a gas chamber G filled with compressed gas is formed on the opposite side of the piston 10 as viewed from the free piston 14.

[0037] In this way, the liquid chamber L and the gas chamber G inside the cylinder 1 are separated by the free piston 14. When the piston rod 11 moves in and out of the cylinder 1 during the extension and retraction of the shock absorber D, the free piston 14 moves up and down (axially) inside the cylinder 1 in FIG.

[0038] The liquid chamber L and the gas chamber G may be separated by a bladder, a bellows, or the like other than the free piston 14. In other words, the configuration of the movable partition that forms the expandable and contractible gas chamber G is not limited to the free piston 14 and can be changed as appropriate. Furthermore, the configuration for compensating for the volume of the piston rod 11 moving in and out of the cylinder 1 is not limited to the gas chamber G and can be changed as appropriate. For example, a reservoir that stores liquid and gas may be provided instead of the gas chamber G, and liquid may be exchanged between the cylinder and the reservoir when the shock absorber expands or contracts. Also, the shock absorber D may be of a double rod type, with piston rods provided on both sides of the piston, in which case the configuration for compensating for the piston rod volume itself can be omitted.

[0039] Next, the fluid chamber L in the cylinder 1 is divided by the piston 10 into an expansion-side chamber L1 on the piston rod 11 side and a compression-side chamber L2 on the opposite side (opposite the piston rod side). As shown in Fig. 2, the piston 10 is cylindrical with a bottom, and includes a cylindrical portion 10b on whose outer periphery a piston ring 10a is attached, which slides against the inner periphery of the cylinder 1, and a bottom portion 10c that closes one end of the cylindrical portion 10b. Hereinafter, for convenience of explanation, the directions corresponding to the top and bottom in Fig. 2 will simply be referred to as "upper" and "lower" unless otherwise specified.

[0040] The piston 10 is then arranged with the bottom 10c facing downward and the cylindrical portion 10b facing upward, and the cylindrical portion 10b is connected to a topped 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. Furthermore, the main valve element 2, which seats on and separates from the valve seat member 16, is provided inside the guide 15 so as to be movable up and down.

[0041] The main valve body 2 has a first valve body portion 2A and a second valve body portion 2B that can be separated into upper and lower portions, and an intermediate chamber L3 is formed between the main valve body 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, the bottom portion 10c of the piston 10 has extension side and compression side ports 10d, 10e that communicate between the intermediate chamber L3 and the compression side chamber L2. Furthermore, an extension side valve 20 that opens and closes the outlet of the extension side port 10d is stacked on the lower side of the bottom portion 10c, and a compression side valve 21 that opens and closes the outlet of the compression side port 10e is stacked on the upper side of the bottom portion 10c.

[0042] The inlet of the expansion-side port 10d opens to the intermediate chamber L3, and the pressure of 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 of 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 of 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 of 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.

[0043] As described above, the main valve body 2 has a first valve body portion 2A and a second valve body portion 2B which can be separated into upper and lower portions. The first valve body portion 2A is annular, and its tip portion is inserted into the inside of the valve seat member 16 so as to be freely movable in the axial direction, and can be seated on and removed from the valve seat member 16. Meanwhile, the second valve body portion 2B includes a head portion 2a and a flange portion 2b which protrudes from the lower end of the head portion 2a toward the outer periphery. The second valve body portion 2B has its lower end seated on and removed from the first valve body portion 2A, with the head portion 2a and the flange portion 2b each in sliding contact with the inner periphery of the guide 15.

[0044] Further, the guide 15 is formed with a through hole 15a that opens into the expansion-side chamber L1, and the pressure of the expansion-side chamber L1 pushes up both the first valve body portion 2A and the second valve body portion 2B, acting in a direction in which the first valve body portion 2A separates from the valve seat member 16. Then, when the first valve body portion 2A moves upward together with the second valve body portion 2B under the pressure of the expansion-side chamber L1 and separates from the valve seat member 16, the liquid in the expansion-side chamber L1 flows through a gap formed between the first valve body portion 2A and the valve seat member 16 toward the intermediate chamber L3.

[0045] The intermediate chamber L3 is formed on the inner circumferential side of the valve seat member 16, the first valve body 2A, and the cylinder portion 10b of the piston 10, between the bottom portion 10c of the piston 10 and the second valve body 2B. The pressure of the intermediate chamber L3 acts on the first valve body 2A in a downward direction and on the second valve body 2B in an upward direction. In other words, the pressure of the intermediate chamber L3 acts in a direction that separates the first valve body 2A and the second valve body 2B into upper and lower parts and causes the second valve body 2B to separate from the first valve body 2A. When the second valve body 2B moves upward and separates from the first valve body 2A under the pressure of the intermediate chamber L3, the liquid in the intermediate chamber L3 flows through the gap between the first valve body 2A and the second valve body 2B and the through hole 15a toward the expansion-side chamber L1.

[0046] To summarize the above, in this embodiment, a main passage M that communicates the expansion-side chamber L1 and the compression-side chamber L2 is formed by the through hole 15a of the guide 15, the intermediate chamber L3, and the expansion-side and compression-side ports 10d, 10e. The main passage M is provided with a main valve element 2, and an expansion-side valve 20 and a compression-side valve 21 are provided in series with the main valve element 2.

[0047] Next, a back pressure chamber L4 is formed on the upper side of the upper surface of the flange portion 2b, which is the back surface of the main valve body 2. The pressure of this back pressure chamber L4 acts in a direction to press down the second valve body portion 2B together with the first valve body portion 2A. In addition, the second valve body portion 2B is provided with a pressure introduction passage p1 having a throttle O in the middle thereof, which reduces the pressure of the expansion side chamber L1 and leads it to the back pressure chamber L4, a pressure control passage p2 connected downstream of the throttle O of this pressure introduction passage p1, and a pressure reduction passage p3 which allows only the flow of liquid from the intermediate chamber L3 to the back pressure chamber L4 and reduces the pressure of the intermediate chamber L3 and leads it to the back pressure chamber L4.

[0048] An electromagnetic valve V including a solenoid S1 according to this embodiment is provided in the pressure control passage p2. The electromagnetic valve V includes a spool 3 as a valve body 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 by receiving 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 a direction to close the spool 3.

[0049] On the other hand, the pressure in the back pressure chamber L4 acts in a direction to push up the spool 3. Then, when the pressure in the back pressure chamber L4 increases and the upward force caused by the pressure overcomes the downward force caused by the solenoid S1, the spool 3 moves upward and leaves 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 from and to the valve seat 22 to open and close the pressure control passage p2 is also referred to as the opening and closing of the solenoid valve V.

[0050] In this embodiment, when the solenoid valve V opens, the liquid in the back pressure chamber L4 flows through the pressure control passage p2 and flows into the upper gap L5 formed between the head 2a of the second valve body 2B and the solenoid S1. This upper gap L5 is connected to the middle chamber L3 by a communication passage p4 formed in the second valve body 2B. As a result, when the solenoid valve V opens, the liquid flows from the back pressure chamber L4 to the upper gap L5 through the pressure control passage p2, and also flows from the upper gap L5 to the middle chamber L3 through the communication passage p4. Furthermore, the communication passage p4 makes the pressures in the upper gap L5 and the middle chamber L3 approximately the same.

[0051] Next, the solenoid S1 of this embodiment includes a coil 4 accommodated axially within the case portion 11a of the piston rod 11, a first fixed core 5 arranged above the coil 4, a second fixed core 6 arranged below the coil 4 with a gap between it and the first fixed core 5, a first movable core 7 and a second movable core 8 arranged between the first fixed core 5 and the second fixed core 6 so as to be movable up and down, a spring 9 that urges the first movable core 7 downward, a leaf spring 90 that limits the amount of downward movement of the first movable core 7 relative to the second movable core 8, and a leaf spring 91 that limits the amount of downward movement of the second movable core 8.

[0052] Here, the direction along center line X passing through the center of coil 4 is the axial direction of coil 4, and up and down here refer to both sides in the axial direction of coil 4. For this reason, it can be said that first fixed core 5 is disposed on one end side of coil 4 in the axial direction, and second fixed core 6 is disposed on the other end side of coil 4 in the axial direction. It can also be said that spring 9 biases first movable core 7 toward second fixed core 6, leaf spring 90 functions as a restricting part that restricts movement of first movable core 7 toward second fixed core 6 relative to second movable core 8, and leaf spring 91 functions as a restricting part that restricts movement of second movable core 8 toward second fixed core 6.

[0053] Each component of the solenoid S1 according to this embodiment will be described in detail below.

[0054] The coil 4 is integrated with a harness 40 for supplying electricity by molded resin, and the harness 40 passes through the inside of the piston rod 11, extends to the outside of the shock absorber D, and is connected to a power source. The first fixed core 5, the second fixed core 6, the first movable core 7, and the second movable core 8 are each made of a magnetic material, and when electricity is applied to the coil 4, a magnetic flux is generated, and the magnetic flux flows through the first fixed core 5, the first movable core 7, the second movable core 8, the second fixed core 6, and the case portion 11a, so that the first movable core 7 is attracted upward toward the first fixed core 5, and the second movable core 8 is attracted downward toward the second fixed core 6.

[0055] Between the first stationary core 5 and the second stationary core 6, an annular filler ring 41 made of a non-magnetic material is interposed, and this filler ring 41 forms a magnetic gap between the first stationary core 5 and the second stationary core 6. Furthermore, the first movable core 7 and the second movable core 8 are disposed 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 (in the axial direction), and the second movable core 8 is inserted inside the filler ring 41 so as to be movable up and down (in the axial direction).

[0056] 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 portion 8a, with the outer bottom portion 8a facing downward (toward the second fixed core 6) and the outer cylinder portion 8b in sliding contact with the inner circumference of the filler ring 41. On the other hand, the first movable core 7, which is an inner cylinder, has an inner bottom portion 7a, an inner cylinder portion 7b standing on the outer peripheral edge of the inner bottom portion 7a, and an annular guide portion 7c located on the outer periphery of the tip portion of the inner cylinder portion 7b, with the inner bottom portion 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 circumference of the filler ring 41.

[0057] The inner bottom 7a of the first movable core 7 has a through hole 7d penetrating through its thickness, and liquid can move through the through hole 7d with relatively little resistance. This prevents liquid from being trapped above the first movable core 7 (on the first fixed core 5 side), ensuring smooth vertical movement of the first movable core 7. A spring 9 is inserted inside the inner cylinder 7b of the first movable core 7. In this embodiment, the spring 9 is a coil spring, and one end of the spring 9 abuts against the inner bottom 7a. Meanwhile, the other end of the spring 9 is supported by the first fixed core 5, and the spring 9 urges the first movable core 7 downward.

[0058] The inner diameter of the outer cylinder 8b of the second movable core 8 is larger than the outer diameter of the inner cylinder 7b of the first movable core 7, and an annular gap is formed between the outer cylinder 8b and the inner cylinder 7b, and liquid can move through the gap relatively without resistance. The outer bottom 8a of the second movable core 8 is formed with a communication hole 8c penetrating its thickness, and liquid can move through the communication hole 8c relatively without resistance. This prevents liquid from being trapped in the space L6 formed above the tip of the outer cylinder 8b (first fixed core 5 side) or the space L7 formed above the outer bottom 8a (first fixed core 5 side), thereby suppressing the generation of a damping force that hinders the movement of the second movable core 8.

[0059] Furthermore, in this embodiment, the first movable core 7 moves up and down (axially) while its guide portion 7c is supported by the filler ring 41, so that it is not 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, so that the filler ring 41 prevents the first movable core 7 from shifting in a direction perpendicular to the center line X of the coil 4 (radial direction). This prevents the first movable core 7 from shifting in the radial direction during its movement, sandwiching the outer tubular portion 8b of the second movable core 8 between the filler ring 41 and the first movable core 7, and increasing the friction during the movement of the second movable core 8. This ensures smooth vertical movement of the second movable core 8.

[0060] Next, leaf springs 90, 91 functioning as regulating parts as described above are arranged above and below the outer bottom part 8a of the second movable core 8. More specifically, the upper leaf spring 90, which is a first regulating part, is located between the outer bottom part 8a of the second movable core 8 and the inner bottom part 7a of the first movable core 7 facing it vertically, and the lower leaf spring 91, which is a second regulating part, is located between the outer bottom part 8a of the second movable core 8 and the second fixed core 6 facing it vertically.

[0061] 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 the 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 the seat portion toward the inner periphery and standing obliquely upward. In this way, 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 impede the flow of liquid.

[0062] 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. 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 it from moving downward any further.

[0063] A through hole is formed in the center of the second fixed core 6, and the shaft portion 3a of the spool 3 is inserted into the through hole so as to be freely movable. The tip of the shaft portion 3a abuts against the outer bottom portion 8a of the second movable core 8. As a result, when the coil 4 is de-energized, the first movable core 7 moves downward under the urging 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 urging force of the spring 9. In contrast, 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 the urging force is no longer transmitted to the spool 3, but the spool 3 receives a downward force due to the force attracting the second movable core 8.

[0064] Furthermore, the leaf spring 90, which is a first restricting portion, restricts the approach between the inner bottom 7a of the first movable core 7 and the outer bottom 8a of the second movable core 8 facing it in the vertical direction (axial direction), thereby preventing the first movable core 7 and the second movable core 8 from being attracted to each other when current is applied to the coil 4. Similarly, the leaf spring 91, which is a second restricting portion, restricts the approach between the outer bottom 8a of the second movable core 8 and the second fixed core 6 facing it in the vertical direction (axial direction), thereby preventing the second movable core 8 from being attracted to the second fixed core 6 when current is applied to the coil 4.

[0065] The first and second restricting portions are not limited to the leaf springs 90 and 91, but may be rings or sheets of non-magnetic material such as rubber, synthetic resin, or aluminum, and in such a case, the rings or sheets may be disposed on the outer periphery of the inlets and outlets of the communication holes 7d and 8c so as not to impede the flow of liquid. Furthermore, as long as 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 impeded, the first and second restricting portions may be magnetic, 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.

[0066] On the other hand, no restricting portion is provided between the first fixed core 5 and the first movable core 7, and the first movable core 7 is attracted to the first fixed core 5 when current is applied to the coil 4. In this manner, when the first movable core 7 is attracted to the first fixed core 5 when current is applied to the coil 4, the first movable core 7 compresses the spring 9, and the attitude of the first movable core 7 can be stably maintained so that the biasing force of the spring 9 is not transmitted to the second movable core 8 side. However, it is not necessary that the first movable core 7 is attracted to the first fixed core 5 when current is applied to the coil 4.

[0067] 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 this Fig. 4, Ia is the minimum amount of current required to attract the first movable core 7, which is 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 between the first fixed core 5 and the first movable core 7. Ic will be described later.

[0068] 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 hits 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 from the spring 9 via the second movable core 8, the leaf spring 90, and the first movable core 7. In other words, 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.

[0069] Next, when the amount of current supplied to the solenoid S1 is increased, the upward force attracting the first movable core 7 to the first fixed core 5 increases, and the downward force attracting the second movable core 8 to the second fixed core 6 also increases. In such a case, in a 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 a region where the amount of current supplied to the solenoid S1 is less than Ia, the downward force applied by the solenoid S1 to the spool 3 decreases as the amount of current supplied to the solenoid S1 increases.

[0070] On the other hand, when the amount of current supplied to the solenoid S1 is increased and the amount of current is equal to or greater than Ia, the first movable core 7 is attracted and attracted to the first fixed core 5 against the biasing force of the spring 9. In this state, the biasing force of the spring 9 is not transmitted to the second movable core 8, and only the force attracting the second movable core 8 to the second fixed core 6 acts in a direction to push down the spool 3. This downward force attracting the second movable core 8 increases in proportion to the amount of current supplied to the solenoid S1, so that in a region where the amount of current supplied to the solenoid S1 is equal to or greater than Ia, the more the amount of current supplied to the solenoid S1 is increased, the greater the downward force that the solenoid S1 applies to the spool 3 in proportion to the amount of current.

[0071] 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 the biasing force of the spring 9 is maintained not to be 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 more the downward force that the solenoid S1 applies to the spool 3 decreases in proportion to the amount of current.

[0072] On the other hand, when the amount of current supplied to the solenoid S1 is reduced and in the region where the amount of current is less than Ib, the attracted state between the first movable core 7 and the first fixed 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 core 8. For this reason, in the region where the amount of current supplied to the solenoid S1 is reduced, the downward force that the solenoid S1 applies to the spool 3 increases.

[0073] As can be seen from Fig. 4, Ib, which is the minimum amount of current required to maintain adhesion between the first movable core 7 and the first fixed core 5, is smaller than Ia, which is the minimum amount of current required to attract the separated first movable core 7 to the first fixed core 5 (Ia>Ib). For this reason, the characteristic of the force that the solenoid S1 applies to the spool 3 relative to the amount of current supplied to the solenoid S1 has hysteresis. Note that in Fig. 4, the region where the amount of current supplied to the solenoid S1 is small is exaggerated for ease of understanding.

[0074] In this embodiment, when controlling the amount of current supplied to the solenoid S1 to control the force that the solenoid S1 applies to the spool 3, a current of Ia or more is once supplied to attract the first movable core 7 to the first fixed core 5, and then the amount of current supplied to the solenoid S1 is controlled within a range of Ic or more, which is larger than Ib. As a result, during normal operation when the amount of current supplied to the solenoid S1 is controlled, the state in which the first movable core 7 is attracted to the first fixed core 5 is maintained, so that the amount of current supplied to the solenoid S1 and the downward force that the solenoid S1 applies to the spool 3 are proportional to each other, and the force increases as the amount of current supplied to the solenoid S1 increases.

[0075] 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 is increased, and decreases as the amount of current supplied is decreased.

[0076] 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 determined in advance according to the specifications of the spring 9, such as the spring constant. Also, the direction of the urging force of the spring 9 that urges the spool 3 in the event of a failure (when not energized) is the same as the direction of the thrust applied to the spool 3 in the normal state.

[0077] 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.

[0078] When the shock absorber D expands, the piston 10 moves upward in the cylinder 1 to compress the expansion-side chamber L1, and the pressure in the expansion-side chamber L1 rises. The liquid in the expansion-side chamber L1 flows into the back pressure chamber L4 through the pressure introduction passage p1, and the pressure in the back pressure chamber L4 rises. When the pressure in the back pressure chamber L4 reaches the valve opening pressure of the spool 3, the spool 3 (solenoid valve V) opens, and the liquid in the back pressure chamber L4 flows through the pressure control passage p2, the upper gap L5, and the communication passage p4 toward the intermediate chamber L3. As a result, when the shock absorber D expands, the pressure in the back pressure chamber L4 is controlled to the valve opening pressure of the solenoid valve V.

[0079] In addition, 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 during expansion of the shock absorber D exceeds the downward force due to the pressure in the back pressure chamber L4 or the like, 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.

[0080] In this way, when the shock absorber D expands, the first valve body portion 2A of the main valve body 2 and the expansion-side valve 20 open, and the main valve body 2 and the expansion-side valve 20 provide resistance to the flow of liquid from the expansion-side chamber L1 to the compression-side chamber L2 through the main passage M. Therefore, when the shock absorber D expands, the pressure in the expansion-side chamber L1 increases, and the shock absorber D exerts an expansion-side damping force that hinders the expansion operation.

[0081] Furthermore, during normal operation when the amount of current supplied to the solenoid S1 is controlled, the more the amount of current supplied to the solenoid S1 is increased, the greater the thrust of the solenoid S1 acting downward (in the closing direction) on the spool 3. For this reason, the more the amount of current supplied to the solenoid S1 is increased, 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.

[0082] 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 becomes, and the greater the damping force on the extension side that is generated. In this way, under normal conditions, the magnitude of the damping force on the extension side 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.

[0083] On the other hand, in the event of a failure where the solenoid S1 is de-energized, the valve opening pressure of the spool 3 (solenoid valve V) is determined according to the biasing force of the spring 9. Therefore, the pressure in the back pressure chamber L4 in the event of a failure is determined according to the specifications of the spring 9, and this determines the damping force on the extension side that is generated. 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 damping force on the extension side in the normal state.

[0084] On the other hand, when the shock absorber D contracts, the piston 10 moves downward in the cylinder 1 to compress the pressure-side chamber L2, and the pressure in the pressure-side chamber L2 rises. 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 downstream of the spool 3 is approximately the same as the pressure in the intermediate chamber L3, and is higher than the pressure in the back pressure chamber L4 located upstream of the spool 3. Therefore, the spool 3 is maintained in a closed state. In this state, the thrust of the solenoid S1 acts downward on the second valve body portion 2B via the spool 3.

[0085] As described above, the pressure in the intermediate chamber L3 acts upward only on the second valve body 2B, so when the upward force acting on the second valve body 2B due to the pressure in the intermediate chamber L3 or the like exceeds the downward force due to the thrust of the solenoid S1 or the like, only the second valve body 2B moves upward. Then, a gap is formed between the second valve body 2B and the first valve body 2A, and the liquid in the intermediate chamber L3 moves through the gap to the expansion-side chamber L1.

[0086] In this way, when the shock absorber D contracts, the compression-side valve 21 and the second valve body portion 2B of the main valve body 2 open, and the compression-side valve 21 and the main valve body 2 provide resistance to the flow of liquid from the compression-side chamber L2 to the expansion-side chamber L1 through the main passage M. For this reason, when the shock absorber D contracts, the pressure in the compression-side chamber L2 increases, and the shock absorber D exerts a compression-side damping force that hinders the contraction operation.

[0087] Also, in the normal state where 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 portion 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 portion 2B in the main valve body 2, and the greater the generated compression side damping force. In this way, in the normal state, the solenoid S1 adjusts the force pushing the second valve body portion 2B downward via the spool 3, thereby adjusting the magnitude of the compression side damping force.

[0088] 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.

[0089] The following describes the effects of the solenoid S1, the electromagnetic valve V including the solenoid S1, and the shock absorber D including the electromagnetic valve V including the solenoid S1 according to this embodiment.

[0090] The solenoid S1 according to the present embodiment includes a coil 4, a first fixed core 5 located at one end of the coil 4 in the axial direction, a second fixed core 6 located at the other end of the coil 4 with a gap therebetween, a first movable core 7 arranged between the first fixed core 5 and the second fixed core 6 and attracted to the first fixed core 5 by energizing the coil 4, a second movable core 8 arranged between the first fixed core 5 and the second fixed core 6 and attracted to the second fixed core 6 by energizing the coil 4, a spring 9 for biasing the first movable core 7 toward the second fixed core 6, and a leaf spring (restricting portion) 90 for restricting the movement of the first movable core 7 toward the second fixed core 6 relative to the second movable core 8. The movement of the first movable core 7 in a direction perpendicular to the axial direction of the coil 4 relative to the first fixed core 5 and the second fixed core 6 is restricted.

[0091] According to the above configuration, when the solenoid S1 is not energized, the first movable core 7 receives the biasing force of the spring 9 and moves toward the second fixed core 6, and when the leaf spring 90 restricts the movement of the first movable core 7 toward the second fixed core 6 relative to the second movable core 8, the first movable core 7 and the second movable core 8 move together toward the second fixed core 6. For this reason, when the solenoid S1 is not energized, the biasing force of the spring 9 is transmitted to the second movable core 8 via the first movable core 7 and the leaf spring 90.

[0092] On the other hand, when the first movable core 7 is attracted to the first fixed core 5 and moves in the direction of attraction when the solenoid S1 is energized, the spring 9 is compressed by the first movable core 7, and the biasing force of the spring 9 is no longer transmitted to the second movable core 8. In addition, when the solenoid S1 is energized, the second movable core 8 is attracted to the second fixed core 6, and the force attracting the second movable core 8 to the second fixed core 6 increases as the amount of current supplied to the solenoid S1 increases.

[0093] Therefore, if the force attracting the second movable core 8 is applied as a thrust to an object such as the spool 3 when the solenoid S1 is energized, 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 decreases as the amount of current supplied to the solenoid S1 decreases. Furthermore, when the solenoid S1 is not energized, the biasing force of the spring 9 acts on the object via the first movable core 7, the leaf spring (regulating portion) 90, and the second movable core 8. The direction of the biasing force of the spring 9 is the same as the direction of the force attracting the second movable core 8 when the solenoid S1 is energized, so according to the above configuration, even when the solenoid S1 is not energized, the object can be biased in the same direction as when it is energized.

[0094] 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 separately. 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.

[0095] In addition, the first movable core 7 of the solenoid S1 of this embodiment is restricted from moving in a direction perpendicular to the axial direction of the coil 4 (the direction along the center line X of the coil 4) relative to the first fixed core 5 and the second fixed core 6. 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 ensures smooth up and down movement of the second movable core 8 without the first movable core 7 shifting in the radial direction impeding the 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 the target as a thrust, it is possible to suppress the occurrence of hysteresis in the thrust characteristics relative to the amount of current supplied to the solenoid S1, and to facilitate control of the thrust.

[0096] The solenoid S1 according to the present 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, has an outer bottom 8a and an outer cylinder portion 8b standing on the outer periphery of the outer bottom 8a, and is inserted inside the filler ring 41 so as to be movable in the axial direction with the outer bottom 8a facing the second stationary core 6. The first movable core 7 is also cylindrical with a bottom, has an inner bottom 7a and an inner cylinder portion 7b standing on the outer periphery of the inner bottom 7a and having an outer diameter smaller than the inner diameter of the outer cylinder portion 8b, and is inserted inside the outer cylinder portion 8b of the second movable core 8 so as to be movable in the axial direction with the inner bottom 7a facing the second stationary core 6. Moreover, the spring 9 has one end inserted inside 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.

[0097] According to the above configuration, when the coil 4 is excited, a 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, so that the first movable core 7 is attracted to the first fixed core 5, and the second movable core 8 is attracted to the second fixed core 6. Furthermore, since the first movable core 7 and the second movable core 8 can be made small while ensuring a space to accommodate the spring 9 inside the first movable core 7, the solenoid S1 can be made small.

[0098] Furthermore, according to the above configuration, when the first movable core 7 moves toward the second fixed core 6, the inner bottom 7a of the first movable core 7 approaches the outer bottom 8a of the second movable core 8, and therefore, if the leaf spring (restriction portion) 90 is arranged to restrict these movements in the approaching direction, the movement of the first movable core 7 toward the second fixed core 6 relative to the second movable core 8 can be restricted. To arrange the leaf spring 90 in this manner, for example, the leaf spring 90 may be arranged between the inner bottom 7a and the outer bottom 8a as in this embodiment, which is easy to do. In other words, according to the above configuration, the leaf spring (restriction portion) 90 can be arranged easily.

[0099] Furthermore, in the solenoid S1, the outer cylinder portion 8b of the second movable core 8 is located between the inner cylinder portion 7b of the first movable core 7 and the filler ring 41, but as described above, the first movable core 7 is restricted from moving in the radial direction (direction perpendicular to the axial direction of the coil 4) relative to the first fixed core 5 and the second fixed core 6. The filler ring 41 is interposed between the first fixed core 5 and the second fixed core 6 and is fixedly provided relative to them. Therefore, according to the solenoid S1, the first movable core 7 does not shift in the radial direction relative to the filler ring 41 when it is attracted to the first fixed core 5. Therefore, according to the solenoid S1, the outer cylinder portion 8b of the second movable core 8 is sandwiched between the first movable core 7 and the filler ring 41 which are shifted in the radial direction, and the sliding resistance during the movement increases, which prevents the smooth up and down movement of the second movable core 8 from being hindered.

[0100] Moreover, the first movable core 7 of the solenoid S1 according to this embodiment has a guide portion 7c located on the outer periphery of the tip of the inner cylinder portion 7b protruding out of the outer cylinder portion 8b of the second movable core 8 and in sliding contact with the inner periphery of the filler ring 41. In this case, the sliding gap between the filler ring 41 and the guide portion 7c is very narrow, and is narrower than the gap 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.

[0101] According to the above configuration, by supporting the guide portion 7c of the first movable core 7 with the filler ring 41, it is possible to prevent the first movable core 7 from shifting radially (in a direction perpendicular to the axial direction of the coil 4) relative to the first fixed core 5 and the second fixed core 6, and the configuration for preventing the shifting can be simplified. Furthermore, according to the above configuration, by increasing the axial length of the guide portion 7c that fits into the filler ring 41, i.e., the fitting length between the filler ring 41 and the guide portion 7c, it is possible to prevent the first movable core 7 from tilting within the filler ring 41 and hindering the smooth vertical movement of the second movable core 8. Therefore, according to the solenoid S1, it is possible to more reliably prevent the first movable core 7 from hindering the smooth vertical movement of the second movable core 8.

[0102] However, the configuration for restricting radial (direction perpendicular to the axial direction of the coil 4) misalignment of the first movable core 7 relative to the first fixed core 5 and the second fixed core 6 is not limited to the above and can be modified as appropriate. Figures 5 and 6 show modified configurations for restricting radial (direction perpendicular to the axial direction of the coil 4) misalignment of the first movable core 7 relative to the first fixed core 5 and the second fixed core 6. Below, each modified example of the solenoid S1 according to this embodiment will be specifically described.

[0103] In a first modified example of the solenoid S1 of this embodiment, as shown in Fig. 5, a recess 5a opening toward the first movable core 7 is formed in the first fixed core 5. The first movable core 7 has a guide portion 7e extending in the axial direction 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 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.

[0104] According to the above configuration, the engagement between the recess 5a of the first fixed core 5 and the guide portion 7e can prevent the first movable core 7 from shifting in the radial direction (the direction perpendicular to the axial direction of the coil 4) relative to the first fixed core 5 and the second fixed core 6, and the configuration for preventing this shift can be simplified. Furthermore, according to the above configuration, by lengthening the axial length of the guide portion 7e to increase the engagement length, the inclination of the first movable core 7 within the filler ring 41 can be suppressed, and the smooth up and down movement of the second movable core 8 can be more reliably prevented from being hindered by the first movable core 7.

[0105] 6, in a second modified example of the solenoid S1 of the present embodiment, 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 7b of the first movable core 7. In this case, the sliding gap between the pipe 50 and the inner cylinder 7b is very narrow, and the difference between the inner diameter of the inner cylinder 7b and the outer diameter of the pipe 50 is smaller than the difference between the inner diameter of the outer cylinder 8b and the outer diameter of the inner cylinder 7b.

[0106] According to the above configuration, the fitting of the pipe 50 provided on the first fixed core 5 with the inner cylindrical portion 7b of the first movable core 7 can prevent the first movable core 7 from shifting in the radial direction (the direction perpendicular to the center line X of the coil 4) relative to the first fixed core 5 and the second fixed core 6, and the configuration for preventing this shifting can be simplified. Furthermore, according to the above configuration, by lengthening the axial length of the pipe 50 to increase the fitting length, the inclination of the first movable core 7 within the filler ring 41 can be suppressed, and the smooth up and down movement of the second movable core 8 can be more reliably prevented from being hindered by the first movable core 7.

[0107] The solenoid S1 according to this embodiment constitutes a solenoid valve V together with a spool (valve element) 3 that opens and closes the pressure control passage p2. The solenoid S1 applies a force that attracts the second movable core 8 toward the second fixed core 6 when the coil 4 is energized to the spool (valve element) 3 in a direction 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.

[0108] 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 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 spool 3. In addition, as described above, in the solenoid S1 of this embodiment, even when not 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 including the solenoid S1 of this embodiment, the valve-opening pressure when not energized can be determined according to the specifications of the spring 9.

[0109] Moreover, the 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 is equipped with 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 relatively in the axial direction, a main valve body 2 that opens and closes this main passage M, a pressure introduction passage p1 having a throttle O provided thereon and reducing and directing the pressure in the main passage M upstream of the main valve body 2 to the back surface of the main valve body 2, and a pressure control passage p2 connected downstream of the throttle O of the pressure introduction passage p1 and in which the solenoid valve V is provided.

[0110] 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, and a damping force due to the resistance is generated. In addition, since 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 damping force generated on the extension side. Therefore, according to the above configuration, the damping force generated on the extension side can be adjusted by changing the amount of current supplied to the solenoid S1.

[0111] 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 body 2 can be, and the greater the generated damping force on the extension side can be.

[0112] That is, in the shock absorber D, the damping force on the extension side that occurs when the amount of current supplied to the solenoid S1 is small can be reduced, so that 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, so that changes in the damping force characteristics (damping force characteristics relative to piston speed) caused by changes in liquid temperature can be reduced.

[0113] In addition, as described above, in the solenoid valve V including the solenoid S1 of this embodiment, the valve opening pressure when de-energized is determined according to the specifications of the spring 9. Therefore, 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 body 2 can be increased even when the solenoid S1 is de-energized. As a result, in the shock absorber D, even in the case of a failure in which the solenoid S1 is de-energized, it is possible to prevent the damping force on the extension side from becoming insufficient. Furthermore, in the shock absorber D, it is only necessary 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 body 2, and there is no need to switch the passage connected to the back pressure chamber L4 depending on whether the solenoid S1 is energized or de-energized. This makes it possible to prevent the structure of the shock absorber D from becoming complicated and reduce costs.

[0114] 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 expanded, and when it is contracted, 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 contracted.

[0115] In addition, the rod that moves in and out of the cylinder 1 does not necessarily have to be a piston rod to which a piston is attached, and the position of the main valve body, the back pressure of which is controlled by the solenoid valve V, is not limited to the piston portion. For example, in the case where the shock absorber has a reservoir as described above, the main valve body may be provided with a passage connecting the expansion-side chamber or the compression-side chamber to the reservoir as the main passage, and the back pressure of the main valve body may be controlled by the solenoid valve V. In addition, in the case where the shock absorber is a uniflow type in which liquid circulates in one direction in the order of the expansion-side chamber, the reservoir, and the compression-side chamber during expansion and contraction, the main valve body may be provided with the circulation passage as the main passage, and the back pressure of the main valve body may be controlled by the solenoid valve V.

[0116] Second embodiment Next, a solenoid S2 according to a second embodiment of the present invention shown in Fig. 7 will be described. The solenoid S2 according to this embodiment is used in a solenoid valve, similar to the solenoid S1 according to the first embodiment, and the solenoid S1 according to the first embodiment shown in Fig. 2 can be directly replaced with the solenoid S2 according to this embodiment. The basic structure of the solenoid S2 according to this embodiment is similar to that of the solenoid S1 according to the first embodiment, and the common components are denoted by the same reference numerals and detailed description thereof will be omitted.

[0117] The major difference between the solenoid S2 of this embodiment and the solenoid S1 of the first embodiment is that the first movable core and the second movable core are arranged in a reversed manner. More specifically, in this embodiment, the first movable core 7A has an inner cylinder portion 7f and an outer cylinder portion 7g arranged in a double manner, a connecting portion 7h connecting one end of these in the axial direction, and an inner bottom portion 7i located at the other end of the inner cylinder portion 7f, and the outer cylinder portion 7g is brought into sliding contact with the inner circumference of the filler ring 41 with the inner bottom portion 7i facing downward (toward the second fixed core 6). On the other hand, the second movable core 8A is a bottomed cylinder having an outer bottom portion 8d and an intermediate cylinder portion 8e standing on the outer peripheral edge of the outer bottom portion 8d, and the intermediate cylinder portion 8e is brought into sliding contact with the inner circumference of the outer cylinder portion 7g of the first movable core 7A with the outer bottom portion 8d facing downward (toward the second fixed core 6).

[0118] The inner bottom 7i of the first movable core 7A has a through hole 7j that penetrates its thickness, and liquid can move through the through hole 7j with relatively little resistance. This prevents liquid from being trapped on the upper side (first fixed core 5 side) of the first movable core 7A, ensuring smooth vertical movement of the first movable core 7A. A spring 9 is inserted inside the inner cylinder 7f of the first movable core 7A. In this embodiment, the spring 9 is also a coil spring, and one end of the spring 9 abuts against the inner bottom 7i. Meanwhile, the other end of the spring 9 is supported by the first fixed core 5, and the spring 9 urges the first movable core 7A downward.

[0119] In addition, the outer bottom 8d of the second movable core 8A is also formed with a communication hole 8f penetrating its thickness, and liquid can move through the communication hole 8f relatively without resistance. The inner diameter of the intermediate cylinder 8e of the second movable core 8A is larger than the outer diameter of the inner cylinder 7f of the first movable core 7A, and an annular gap is formed between the intermediate cylinder 8e and the inner cylinder 7f. Therefore, the space L8 formed above the tip of the intermediate cylinder 8e (on the first fixed core 5 side) and the space L9 formed between the outer bottom 8d and the inner bottom 7a are continuous. And, since the communication hole 8f is connected to the continuous space, liquid is trapped in the space, and it is possible to suppress the generation of a damping force that hinders the movement of the second movable core 8A.

[0120] Furthermore, in this embodiment, the first movable core 7A moves up and down (axially) while its outer cylinder portion 7g is supported by the filler ring 41, and therefore 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 these, so that the filler ring 41 prevents the first movable core 7A from shifting in a direction perpendicular to the center line of the coil (radial direction).

[0121] Also, the second movable core 8A moves up and down (axially) while its intermediate cylinder portion 8e is supported by the outer cylinder portion 7g of the first movable core 7A. In this manner, in the solenoid S2 of the present embodiment, the second movable core 8A is inserted further inside the first movable core 7A inserted into the filler ring 41. This prevents the first movable core 7A from shifting radially when attracted to the first fixed core 5, and prevents the second movable core 8A from being pinched between the first movable core 7A shifted radially and the filler ring 41, and there is no concern that the second movable core 8A will be pinched between the first movable core 7A shifted radially and the filler ring 41, increasing the sliding resistance during its movement.

[0122] In addition, in this embodiment, as shown in FIG. 7(b), a protrusion 7k protruding toward the center is provided on the inner periphery of the tip of the outer cylinder portion 7g of the first movable core 7A, and the protrusion 7k holds a fluororesin sheet 70 on the inner periphery of the outer cylinder portion 7g. This improves the sliding property between the intermediate cylinder portion 8e of the second movable core 8A and the outer cylinder portion 7g of the first movable core 7A. The material of the sheet 70 is not limited to fluororesin and can be changed as appropriate as long as it has good sliding properties. Furthermore, the sheet 70 may be omitted and the intermediate cylinder portion 8e may be directly in sliding contact with the inner periphery of the outer cylinder portion 7g.

[0123] Next, in this embodiment as well, leaf springs 90, 91 functioning as regulating parts are arranged above and below the outer bottom 8d of the second movable core 8A. More specifically, the upper leaf spring 90, which is a first regulating part, is located between the outer bottom 8d of the second movable core 8A and the inner bottom 7i of the first movable core 7A facing it vertically, and the lower leaf spring 91, which is a second regulating part, is located between the outer bottom 8d of the second movable core 8A and the second fixed core 6 facing it vertically.

[0124] As the first movable core 7A moves downward relative to the second movable core 8A, the inner bottom 7i of the first movable core 7A hits the leaf spring 90. This restricts the downward movement of the first movable core 7A relative to the second movable core 8A, and thereafter the first movable core 7A and the second movable core 8A move downward together. As the second movable core 8A moves downward, the outer bottom 8d of the second movable core 8A hits the leaf spring 91 and compresses it, preventing it from moving downward any further.

[0125] Furthermore, a through hole is formed in the center of the second fixed core 6, and the shaft portion 3a of the spool 3 is inserted into the through hole so as to be freely movable. The tip of the shaft portion 3a abuts against the outer bottom portion 8d of the second movable core 8A. As a result, when the coil is de-energized, the first movable core 7A moves downward under the urging force of the spring 9 and abuts against the second movable core 8A via the leaf spring 90, so that the spool 3 receives a downward force due to the urging 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 urging force is no longer transmitted to the spool 3, but the spool 3 receives a downward force due to the force attracting the second movable core 8A.

[0126] Furthermore, the leaf spring 90, which is the first restricting portion, restricts the approach between the inner bottom 7i of the first movable core 7A and the outer bottom 8d of the second movable core 8A facing it in the vertical direction (axial direction), thereby preventing the first movable core 7A and the second movable core 8A from being attracted to each other 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 8d of the second movable core 8A and the second fixed core 6 facing it in the vertical direction (axial direction), thereby preventing the second movable core 8A from being attracted 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 in the same manner as in the first embodiment.

[0127] 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 the spring 9 is not transmitted to the second movable core 8A side. However, the first movable core 7A does not necessarily have to be attracted to the first fixed core 5 when current is applied to the coil.

[0128] The relationship between the amount of current supplied to the solenoid S2 according to this embodiment and the force that the solenoid S2 exerts on the spool (object) 3 is as shown in Fig. 4, similar to the solenoid S1 according to the first embodiment. The operation of the shock absorber equipped with the solenoid valve including the solenoid S2 according to this embodiment is similar to the operation of the shock absorber D equipped with the solenoid valve V including the solenoid S1 according to the first embodiment.

[0129] The effects of the solenoid S2 according to this embodiment will be described below. Note that the same configuration as the solenoid S1 of the first embodiment has the same effects, and detailed description thereof will be omitted here. 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 also the same as those of the solenoid S1, the solenoid valve V including the solenoid S1, and the shock absorber D including the solenoid valve V including the solenoid S1 of the first embodiment, and detailed description thereof will be omitted here.

[0130] The solenoid S2 according to the present embodiment includes a coil, a first fixed core 5 located at one end of the coil in the axial direction, a second fixed core 6 located at the other end of the coil with a gap from the first fixed core 5, a first movable core 7A arranged between the first fixed core 5 and the second fixed core 6 and attracted to the first fixed core 5 by energizing the coil, a second movable core 8A arranged between the first fixed core 5 and the second fixed core 6 and attracted to the second fixed core 6 by energizing the coil, a spring 9 for biasing the first movable core 7A toward the second fixed core 6, and a leaf spring (restricting portion) 90 for restricting the movement of the first movable core 7A toward the second fixed core 6 relative to the second movable core 8A. The movement of the first movable core 7A in a direction perpendicular to the axial direction of the coil relative to the first fixed core 5 and the second fixed core 6 is restricted.

[0131] According to the above configuration, when the solenoid S2 is not energized, the first movable core 7A receives the biasing force of the spring 9 and moves toward the second fixed core 6, and when the leaf spring 90 restricts the movement of the first movable core 7A toward the second fixed core 6 relative to the second movable core 8A, the first movable core 7A and the second movable core 8A move together toward the second fixed core 6. For this reason, when the solenoid S2 is not energized, the biasing force of the spring 9 is transmitted to the second movable core 8A via the first movable core 7A and the leaf spring 90.

[0132] On the other hand, when the first movable core 7A is attracted to the first fixed core 5 and moves in the direction of attraction when the solenoid S2 is energized, the spring 9 is compressed by the first movable core 7A and the biasing force of the spring 9 is no longer transmitted to the second movable core 8A. Also, when the solenoid S2 is energized, the second movable core 8A is attracted to the second fixed core 6, and the force attracting the second movable core 8A to the second fixed core 6 increases as the amount of current supplied to the solenoid S2 increases.

[0133] Therefore, if the force attracting the second movable core 8A is applied as a thrust to an object such as the spool 3 when the solenoid S2 is energized, 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 decreases as the amount of current supplied to the solenoid S2 decreases. Furthermore, when the solenoid S2 is not energized, the biasing force of the spring 9 acts on the object via the first movable core 7A, the leaf spring (regulating portion) 90, and the second movable core 8A. Since the direction of the biasing force of the spring 9 is the same as the direction of the force attracting the second movable core 8A when the solenoid S2 is energized, according to the above configuration, even when the solenoid S2 is not energized, the object can be biased in the same direction as when the solenoid S2 is energized.

[0134] 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 separately. 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.

[0135] In addition, the first movable core 7A of the solenoid S2 of this embodiment is restricted from moving in a direction perpendicular to the axial direction of the coil (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 ensures smooth up and down movement of the second movable core 8A without the first movable core 7A displaced in the radial direction impeding the 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 the target as a thrust, it is possible to suppress the occurrence of hysteresis in the thrust characteristics relative to the amount of current supplied to the solenoid S2, and to facilitate control of the thrust.

[0136] The solenoid S2 according to the present 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 cylinder 7f and an outer cylinder 7g arranged in a double layer, a connecting portion 7h connecting one axial end of the inner cylinder 7f and the outer cylinder 7g, and an inner bottom 7i located at the other end of the inner cylinder 7f, and the inner bottom 7i is slidably inserted inside the filler ring 41 toward the second stationary core 6. On the other hand, the second movable core 8A is cylindrical with a bottom, and has an outer bottom 8d and an intermediate cylinder 8e standing on the outer peripheral edge of the outer bottom 8d and having an inner diameter larger than the outer diameter of the inner cylinder 7f of the first movable core 7A, and the intermediate cylinder 8e is slidably inserted inside the outer cylinder 7g of the first movable core 7A with the outer bottom 8d facing the second stationary core 6. Furthermore, the spring 9 is interposed between the inner bottom portion 7i and the first fixed core 5 with one end side inserted into the inner cylindrical portion 7f of the first movable core 7A.

[0137] 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.

[0138] Furthermore, according to 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, so if the leaf spring (restriction portion) 90 is arranged to restrict these movements in the approaching direction, the movement of the first movable core 7A toward the second fixed core 6 relative to the second movable core 8A can be restricted. To arrange the leaf spring 90 in this manner, for example, the leaf spring 90 may be arranged 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, which is easy to do. In other words, according to the above configuration, the leaf spring (restriction portion) 90 can be arranged easily.

[0139] Furthermore, in the solenoid S2, the intermediate cylinder portion 8e of the second movable core 8A is slidably inserted inside the outer cylinder portion 7g of the first movable core 7A slidably inserted into the filler ring 41. In this way, the second movable core 8A is inserted further inside the first movable core 7A inserted into the filler ring 41, so that the first movable core 7A does not shift radially when attracted to the first fixed core 5, and the second movable core 8A is not sandwiched between the first movable core 7A shifted radially and the filler ring 41. Therefore, according to the above configuration, the second movable core 8A is sandwiched between the first movable core 7A shifted radially and the filler ring 41, increasing the sliding resistance during the movement, which prevents the smooth up and down movement of the second movable core 8A from being hindered.

[0140] Although the preferred embodiment of the present invention has been described in detail above, modifications, variations and changes can be made without departing from the scope of the appended claims. [Explanation of symbols]

[0141] D···Shock absorber, 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 core, 5a···Recess, 6···Second fixed core, 7, 7A···First movable core, 7a, 7i ···Inner bottom portion, 7b, 7f···Inner cylinder portion, 7c, 7e···Guide portion, 7g···Outer cylinder portion, 7h···Connecting portion, 8, 8A···Second movable core, 8a, 8d···Outer bottom portion, 8b···Outer cylinder portion, 8e···Intermediate cylinder portion, 9···Spring, 11···Piston rod (rod), 41···Filler ring, 50···Pipe, 90···Leaf spring (restricting portion)

Claims

1. A coil and A first fixed core located at one end side in the axial direction of the coil; a second stationary core located on the other axial end side of the coil with a gap from the first stationary core; an annular filler ring interposed between the first stationary core and the second stationary core; a first movable core disposed between the first fixed core and the second fixed core and attracted to the first fixed core when current is applied to the coil; a second movable core disposed between the first fixed core and the second fixed core and attracted to the second fixed core when current is applied to the coil; a spring that biases the first movable core toward the second fixed core; a restricting portion that restricts movement of the first movable core toward the second fixed core relative to the second movable core, the second movable core is a bottomed cylindrical member having an outer bottom portion and an outer tubular portion standing on an outer peripheral edge of the outer bottom portion, and is inserted inside the filler ring so as to be axially movable with the outer bottom portion toward the second fixed core side; the first movable core is cylindrical with a bottom, and has an inner bottom portion and an inner cylindrical portion standing on an outer peripheral edge of the inner bottom portion and having an outer diameter smaller than an inner diameter of the outer cylindrical portion, and the inner cylindrical portion is inserted into the outer cylindrical portion so as to be axially movable with the inner bottom portion facing the second fixed core side, The spring has one end inserted into the inner cylinder portion and is interposed between the inner bottom portion and the first fixed core, The first movable core is restricted from moving relative to the first fixed core and the second fixed core in a direction perpendicular to the axial direction of the coil. A solenoid characterized by:

2. A coil and A first fixed core located at one end side in the axial direction of the coil; a second stationary core located on the other axial end side of the coil with a gap from the first stationary core; a first movable core disposed between the first fixed core and the second fixed core and attracted to the first fixed core when current is applied to the coil; a second movable core disposed between the first fixed core and the second fixed core and attracted to the second fixed core when current is applied to the coil; a spring that biases the first movable core toward the second fixed core; a restricting portion that restricts movement of the first movable core toward the second fixed core relative to the second movable core, the first movable core is restricted from moving relative to the first fixed core and the second fixed core in a direction perpendicular to an axial direction of the coil, The restricting portion is a leaf spring having a ring-shaped seat and a plurality of legs standing up from the seat. A solenoid characterized by:

3. The first movable core has a guide portion located on the outer periphery of the tip end of the inner cylindrical portion protruding outward from the outer cylindrical portion and in sliding contact with the inner periphery of the filler ring.

2. The solenoid of claim 1.

4. The first fixed core has a recess formed therein that opens toward the first movable core, The first movable core has a guide portion that extends in the axial direction from the tip of the inner cylindrical portion and is slidably inserted into the recess.

2. The solenoid of claim 1.

5. A pipe is attached to the first fixed core and is slidably inserted inside the inner cylindrical portion.

2. The solenoid of claim 1.

6. the filler ring is fixed between the first stationary iron core and the second stationary iron core, The outer cylinder portion of the second movable core is prevented from being pinched between the first movable core and the filler ring.

2. The solenoid of claim 1.

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

8. A shock absorber comprising the solenoid valve according to claim 7, A cylinder; A rod that is 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 having a throttle provided therein, for reducing and guiding the pressure in the main passage upstream of the main valve body to a back surface of the main valve body; the pressure control passage is connected downstream of the throttle of the pressure introduction passage and has the solenoid valve provided therein; A shock absorber characterized by:

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