solenoids, electromagnetic valves and dampers

Abstract

The solenoid (S1) of the present application has: a first fixed core (5) and a second fixed core (6) respectively located at one end side and the other end side of the coil (4) in the axial direction; a first movable core (7) and a second movable core (8) located between the first fixed core (5) and the second fixed core (6) and respectively attracted by the first fixed core (5) and the second fixed core (6) by energizing the coil (4); a spring (9) which applies a force to the first movable core (7) toward the second fixed core (6) side; a leaf spring (90) which restricts the movement of the first movable core (7) toward the second fixed core (6) side with respect to the second movable core (8); and a communication passage (p5) which communicates the first fixed core (5) side and the second fixed core (6) side of the second movable core (8).

Description

Technical Field

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

[0002] Conventionally, a solenoid consists of a coil and a movable iron core. When the coil is energized, the movable iron core generates a magnetic field, generating magnetic flux that attracts the movable iron core toward one side of the coil's axis. This force, which attracts the movable iron core, acts as thrust on another component (target), and this thrust can be varied depending on the amount of current flowing through it. This type of solenoid is used, for example, in solenoid valves.

[0003] This solenoid valve is located midway in the pressure control channel and, in addition to a solenoid, includes a valve body that opens and closes the pressure control channel and a spring that urges the valve body in the opening direction. The solenoid applies a closing force to the valve body. With this solenoid valve, the greater the current supplied to the solenoid, the higher the valve opening pressure, thereby increasing the pressure upstream of the solenoid valve. This type of solenoid valve is used, for example, in shock absorbers.

[0004] Furthermore, this shock absorber comprises, in addition to a solenoid valve, a main channel through which fluid flows when the shock absorber expands and contracts, and a main valve body that opens and closes the main channel. The pressure control channel containing the solenoid valve is connected to a backpressure chamber formed on the back side of the main valve body. With this shock absorber, the backpressure (the pressure in the backpressure chamber) in the main valve body increases as the current supplied to the solenoid and the opening pressure of the solenoid valve increases, thereby generating a greater damping force (e.g., Patent Document 1).

[0005] Prior art literature

[0006] Patent Literature

[0007] Patent Document 1: Japanese Patent Application Laid-Open No. 2014-173716 Summary of the Invention

[0008] Problems to be solved by the invention

[0009] Therefore, when shock absorbers are used in vehicle suspensions, it is desirable to maintain good ride comfort during normal driving on clear roads while reducing the damping force generated during normal driving. Furthermore, in shock absorbers equipped with a solenoid valve containing a conventional solenoid, reducing the current supplied to the solenoid can reduce the generated damping force, thereby suppressing power consumption during normal driving and saving electricity. However, in conventional shock absorbers, if the solenoid fails, the solenoid valve fully opens, minimizing the back pressure in the main valve body, and the damping force during the fault condition becomes insufficient.

[0010] Therefore, in the damper described in Japanese Patent Application Publication No. 2014-173716, the valve body of the electromagnetic valve provided in the damper has two opening and closing portions that open and close the pressure control passage. Moreover, one of the opening and closing portions is biased in the opening direction by a spring, and functions as the opening and closing portion at the time of pressure control by the force applied to the valve body in the closing direction by the solenoid. The other opening and closing portion, on the other hand, closes the downstream side of the portion of the pressure control passage that is opened and closed by the one opening and closing portion in a state in which the one opening and closing portion is fully open due to the biasing force of the spring when the solenoid is not energized.

[0011] Moreover, the damper described above further includes a failure passage that is connected between the portion of the pressure control passage that is opened and closed by the one opening and closing portion and the portion that is opened and closed by the other opening and closing portion, and has a passive valve provided midway. Thus, when the solenoid is not energized, if the pressure control passage is closed by the other opening and closing portion in the electromagnetic valve, the liquid in the back pressure chamber flows through the failure passage, and the back pressure of the main valve body is set to the opening pressure of the passive valve. Therefore, even in the conventional damper, the damping force of the damper does not become insufficient when a failure occurs.

[0012] However, as in the damper described above, two passages, the pressure control passage and the failure passage, are provided as the passages connected to the back pressure chamber that sets the back pressure of the main valve body, and the passage connected to the back pressure chamber is switched between when the solenoid is energized and when the solenoid is not energized, in which case, the structure of the damper becomes complex, and a considerable cost is required. However, in a case in which the valve body of the electromagnetic valve is biased in the closing direction by a spring, and the valve body is applied with a force in the opening direction by a solenoid, although it is not necessary to switch the passage connected to the back pressure chamber between when the solenoid is energized and when the solenoid is not energized, when it is desired to reduce the damping force generated, it is necessary to increase the amount of current supplied to the solenoid, and thus the power consumption during normal travel increases.

[0013] That is, in a case in which a solenoid is used in a damper, an electromagnetic valve, or the like in which the damping force is variable, when the amount of current supplied to the solenoid is small, it is desirable to reduce the force applied to the object target by the solenoid, and at times it is desirable to apply a force in the same direction as the above-described force to the object target even when the solenoid is not energized, which is not possible with conventional solenoids. Therefore, in a case in which a conventional solenoid is used in a damper, an electromagnetic valve, or the like in which the damping force is variable, there is a problem in that the structure of the damper becomes complex, or the power consumption during normal travel of the vehicle increases.

[0014] Therefore, the present application was created in order to solve such a problem, and has as its object to provide a solenoid, an electromagnetic valve, and a damper in which, when the amount of current supplied to the solenoid is small, the force applied to an object target by the solenoid can be reduced, and even when the solenoid is not energized, the solenoid can apply a force to the object target in the same direction as the force when the solenoid is energized.

[0015] Solution for solving the problem

[0016] A solenoid that solves the above-mentioned problem comprises: a first fixed iron core and a second fixed iron core, respectively located at one end side and the other end side of the axial direction of the coil; a first movable iron core and a second movable iron core, located between the first fixed iron core and the second fixed iron core, and attracted by the first fixed iron core and the second fixed iron core, respectively, when the coil is energized; a spring that applies force to the first movable iron core toward the second fixed iron core; a limiting portion that limits the movement of the first movable iron core toward the second fixed iron core relative to the second movable iron core; and a connecting channel that connects the first fixed iron core side and the second fixed iron core side of the second movable iron core.

[0017] According to the above structure, when the solenoid is de-energized, the first movable iron core is urged toward the second fixed iron core by the spring. When the first movable iron core's movement toward the second fixed iron core relative to the second movable iron core is restricted by the restricting portion, the spring force is transmitted from the first movable iron core to the second movable iron core via the restricting portion. On the other hand, when the solenoid is energized, if the first movable iron core is attracted to the first fixed iron core and moves in the direction of attraction, the spring is compressed by the first movable iron core, and the spring force is not transmitted to the second movable iron core. Furthermore, when the solenoid is energized, the second movable iron core is attracted to the second fixed iron core, and the greater the current supplied to the solenoid, the greater the force pulling the second movable iron core toward the second fixed iron core.

[0018] Therefore, if the force that attracts the second movable iron core is applied to the target as thrust when the solenoid is energized, the greater the current supplied to the solenoid, the greater the thrust applied to the target, and the smaller the current supplied to the solenoid, the smaller the thrust applied to the target. Furthermore, when the solenoid is not energized, the force of the spring acts on the target via the first movable iron core, the restricting portion, and the second movable iron core. Because the direction of the spring force is the same as the direction of the force that attracts the second movable iron core when the solenoid is energized, according to the above structure, even when the solenoid is not energized, force can be applied to the target in the same direction as when it is energized.

[0019] Furthermore, according to the above configuration, the provision of a communication passage connecting the first fixed iron core side and the second fixed iron core side of the second movable iron core prevents the liquid from being sealed in the first fixed iron core side of the second movable iron core, thereby suppressing the generation of a damping force that would hinder the movement of the second movable iron core. Therefore, even when the second movable iron core is moving at a high speed, the second movable iron core can still move smoothly.

[0020] Further, the above solenoid can also have a ring-shaped packing ring installed between the first fixed core and the second fixed core, and the second movable core can be a bottomed cylinder having an outer bottom and an outer cylinder portion, the outer bottom facing the second fixed core side and being axially movably inserted into the inside of the packing ring, the first movable core can be a bottomed cylinder having an inner bottom and an inner cylinder portion, the inner bottom facing the second fixed core side and the inner cylinder portion being axially movably inserted into the inside of the outer cylinder portion, and the spring can be installed between the inner bottom and the first fixed core with one end side inserted into the inside of the inner cylinder portion.

[0021] According to the above structure, 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 can be attracted toward the first fixed core and the second movable core can be attracted toward the second fixed core. Further, it is also possible to ensure a space for accommodating the spring inside the first movable core while miniaturizing the small solenoid.

[0022] In addition, according to the above structure, when the first movable core moves toward the second fixed core side, the inner bottom of the first movable core approaches the outer bottom of the second movable core. Therefore, if the configuration restricting portion is configured to be able to restrict movement in this approach direction, the movement of the first movable core toward the second fixed core side with respect to the second movable core can be restricted by the configuration restricting portion, and the configuration restricting portion can be easily configured.

[0023] Further, in the above solenoid, a communication passage can be formed in the outer bottom, open between the outer bottom and the inner bottom, and communicate to a space formed on the first fixed core side of the outer cylinder portion via a gap formed between the outer cylinder portion and the inner cylinder portion. In this way, it is possible to prevent liquid from being trapped in the space formed between the outer bottom and the inner bottom and on the first fixed core side of the outer cylinder portion, and to effectively suppress the generation of damping force that hinders the movement of the second movable core.

[0024] Further, in the above solenoid, the first movable core can have a guide portion located at the outer periphery of the front end portion of the inner cylinder portion protruding outward of the outer cylinder portion, in sliding contact with the inner periphery of the packing ring, and the outer diameter of the inner cylinder portion can be set to be smaller than the inner diameter of the outer cylinder portion. In this way, the gap formed between the inner cylinder portion and the outer cylinder portion becomes annular, and the flow path area thereof can be increased.

[0025] Alternatively, in the solenoid, a communication passage may be formed in the outer bottom portion, opening between the outer bottom portion and the inner bottom portion, and connected to the space formed in the outer tube portion on the first fixed core side via a communication hole formed in the inner bottom portion and a gap formed between the front end of the inner tube portion and the first fixed core. In this case, liquid can be prevented from being enclosed in the space formed between the outer bottom portion and the inner bottom portion and in the space formed in the outer tube portion on the first fixed core side, thereby reliably suppressing the generation of a damping force that would hinder the movement of the second movable core.

[0026] Alternatively, the solenoid may include a first communicating channel formed in the outer bottom portion and opening between the outer and inner bottom portions, and a second communicating channel formed between the second movable iron core and the filling ring and opening into the space formed in the outer cylinder on the first fixed iron core side. In this case, liquid can be prevented from being enclosed in the space formed between the outer and inner bottom portions and in the space in the outer cylinder on the first fixed iron core side, thereby reliably suppressing the generation of a damping force that would hinder the movement of the second movable iron core.

[0027] In addition, the solenoid can also be provided with an annular filling ring, which is installed between the first fixed iron core and the second fixed iron core, and the first movable iron core has: an inner tube part and an outer tube part arranged in two layers inside and outside; a connecting part connecting one axial end of them; and an inner bottom part located at the other end of the inner tube part, and the inner bottom part is slidably inserted into the inner side of the filling ring toward the second fixed iron core side, and the second movable iron core is a bottomed cylinder, having an outer bottom part and an intermediate tube part with an inner diameter larger than the outer diameter of the inner tube part, and the outer bottom part is directed toward the second fixed iron core side, and the intermediate tube part is slidably inserted into the inner side of the outer tube part, and the spring is installed between the inner bottom part and the first fixed iron core in a manner that one end side is inserted into the inner side of the inner tube part.

[0028] With this structure, when the coil is excited, a magnetic circuit passes through the first fixed iron core, the first movable iron core, the second movable iron core, and the second fixed iron core, thereby attracting the first movable iron core toward the first fixed iron core and the second movable iron core toward the second fixed iron core. Furthermore, space for accommodating the spring is ensured inside the first movable iron core.

[0029] Furthermore, according to the above configuration, when the first movable iron core moves toward the second fixed iron core, the inner bottom portion of the first movable iron core approaches the outer bottom portion of the second movable iron core. Therefore, if a restricting portion is provided to restrict movement in this approaching direction, the restricting portion can be used to restrict movement of the first movable iron core relative to the second movable iron core toward the second fixed iron core, making it easier to configure the restricting portion.

[0030] Furthermore, according to the above structure, due to the gap between the inner cylindrical portion and the intermediate cylindrical portion, a continuous space is formed between the first movable iron core and the second movable iron core inserted therein. Therefore, by providing a connecting passage to open this space toward the second fixed iron core side of the second movable iron core, it is possible to prevent liquid from being enclosed on the first fixed iron core side of the second movable iron core, that is, between the second movable iron core and the first movable iron core, and to reliably suppress the generation of a damping force that would hinder the movement of the second movable iron core.

[0031] Alternatively, the solenoid can be mounted on a solenoid valve located midway in the pressure control passage. This solenoid valve includes, in addition to the solenoid, a valve body that opens and closes the pressure control passage. When the solenoid coil is energized, the solenoid exerts a force on the valve body that pulls the second movable core toward the second fixed core, closing the pressure control passage. In this manner, the solenoid valve's opening pressure can be adjusted by varying the current supplied to the solenoid, with the pressure upstream of the solenoid valve being set as the valve opening pressure.

[0032] As mentioned above, the greater the current supplied to the solenoid, the greater the thrust applied to the target. Therefore, in the solenoid valve, the greater the current supplied to the solenoid, the greater the thrust applied to the valve body in the closing direction, thereby increasing the valve opening pressure. Furthermore, as mentioned above, the solenoid can exert a force on the target in the same direction as the thrust applied when energized, even when de-energized. Therefore, the de-energized valve opening pressure in the solenoid valve can be determined based on the spring specifications.

[0033] In addition, the solenoid valve including the above-mentioned solenoid can also be set in a buffer, which includes: a cylinder; a rod, which is movably inserted into the cylinder along the axial direction; a main channel, which allows liquid to flow when the cylinder and the rod move relative to each other in the axial direction; a main valve body, which opens and closes the main channel; a pressure inlet channel, which is provided with a throttle in the middle to guide the pressure reduction on the upstream side of the main valve body of the main channel to the back side of the main valve body; and a pressure control channel, which is connected to the downstream of the throttle of the pressure inlet channel and is provided with the above-mentioned solenoid valve.

[0034] In this way, when the cylinder and rod move relative to each other in the axial direction, the main valve body exerts resistance on the flow of fluid through the main channel, and the shock absorber generates a damping force due to this resistance. Furthermore, 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 varying the amount of current supplied to the solenoid. Furthermore, the higher the back pressure of the main valve body, the harder it is to open the main valve body, and the greater the damping force generated. Therefore, with this structure, the magnitude of the damping force generated can be adjusted by varying the amount of current supplied to the solenoid.

[0035] Furthermore, as described above, in the solenoid valve, a greater current supplied to the solenoid increases the solenoid's valve-opening pressure. Therefore, in the damper, a greater current supplied to the solenoid increases the back pressure on the main valve body, thereby increasing the generated damping force. In other words, in the damper, a lower current supplied to the solenoid reduces the generated damping force. Therefore, when the damper is used in a vehicle suspension, power consumption during normal driving can be reduced. Furthermore, this suppresses solenoid heat generation, minimizing temperature fluctuations in the damper, thereby reducing variations in damping force characteristics (damping force characteristics relative to piston velocity) caused by changes in fluid temperature.

[0036] Furthermore, as described above, in the solenoid valve, since the valve opening pressure when de-energized is determined by the spring specifications, the damper can increase the back pressure of the main valve body even when the solenoid is de-energized. This prevents the damper from experiencing insufficient damping force during a malfunction. Furthermore, in the damper, since a pressure control channel is sufficient to set the back pressure of the main valve body, there is no need to switch the channel used to set the back pressure when the solenoid is energized or de-energized. This reduces the complexity of the damper structure and reduces costs.

[0037] Effects of the Invention

[0038] According to the solenoid, electromagnetic valve, and buffer provided by the present invention, when the amount of current supplied to the solenoid is small, the thrust applied by the solenoid to the target object can be reduced, and even when the solenoid is not energized, the thrust applied to the target object can be applied in the same direction as the thrust when energized. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 It is a longitudinal sectional view of a shock absorber provided with a solenoid valve including a solenoid according to the first embodiment of the present invention.

[0040] Figure 2 It is an enlarged longitudinal sectional view showing a solenoid valve including a solenoid according to the first embodiment of the present invention.

[0041] Figure 3 It is a partially enlarged cross-sectional view of the solenoid according to the first embodiment of the present invention.

[0042] Figure 4 This is a characteristic diagram showing the relationship between the amount of supplied current and the force acting in the direction of pressing down the valve body in the solenoid according to the first embodiment of the present invention.

[0043] Figure 5 FIG. 1 shows a first modified example of the solenoid according to the first embodiment of the present invention, and is a partially enlarged cross-sectional view of the solenoid according to the modified example.

[0044] Figure 6 FIG. 1 shows a second modified example of the solenoid according to the first embodiment of the present invention, and is a partially enlarged cross-sectional view of the solenoid according to the modified example.

[0045] Figure 7 It is a partially enlarged cross-sectional view of a solenoid according to a second embodiment of the present invention. DETAILED DESCRIPTION

[0046] The embodiments of the present invention will be described below with reference to the accompanying drawings. In the multiple drawings, the same reference numerals are used to represent the same components (parts) or corresponding components (parts).

[0047] In each embodiment, a solenoid is used in a solenoid valve, the solenoid valve is used in a shock absorber, and the shock absorber is 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 this and can be modified as appropriate.

[0048] <First embodiment>

[0049] like Figure 1 As shown, a shock absorber D having a solenoid valve V including a solenoid according to the first embodiment of the present invention comprises 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 projecting out of the cylinder 1. Furthermore, one of the vehicle body and the axle is connected to the cylinder 1, while the other is connected to the piston rod 11. Thus, the shock absorber D is mounted between the vehicle body and the axle.

[0050] Moreover, when the vehicle is running on an uneven road, the wheels vibrate up and down, the piston rod 11 moves in and out of the cylinder 1, the buffer D expands and contracts, and the piston 10 moves along the inside of the cylinder 1. Figure 1 In the up and down (axial) direction. In addition, Figure 1 1 shows a state where the piston rod 11 protrudes upward from the cylinder 1, but the shock absorber D can be mounted on the vehicle in any orientation.

[0051] Next, an annular head member 12 is attached to one axial end of the cylinder 1, through which the piston rod 11 is inserted. This head member 12 slidably supports the piston rod 11 and seals one end of the cylinder 1. Meanwhile, the other end of the cylinder 1 is sealed by a bottom cap 13. This seals the interior of the cylinder 1, confining the liquid and gas within.

[0052] More specifically, when viewed from the piston 10 side, the free piston 14 is slidably inserted into the cylinder 1 on the side opposite to the piston rod 11. Furthermore, a liquid chamber L for filling with a liquid such as hydraulic oil is formed within the cylinder 1 on the piston 10 side of the free piston 14. On the other hand, a gas chamber G for confining compressed gas is formed within the cylinder 1 on the side opposite to the piston 10 when viewed from the free piston 14 side.

[0053] In this way, the liquid chamber L and the gas chamber G in the cylinder 1 are separated by the free piston 14. Moreover, when the piston rod 11 enters and exits the cylinder 1 during the expansion and contraction of the buffer D, the free piston 14 is in the cylinder 1. Figure 1 The up and down (axial) movement causes the gas chamber G to expand or shrink, compensating for the volume of the piston rod 11 entering and exiting the cylinder 1.

[0054] In addition, in addition to the free piston 14, the liquid chamber L and the gas chamber G may also be separated by an air bag or a bellows. That is, the structure of the movable partition wall that forms the gas chamber G that can expand and contract is not limited to the free piston 14, and can be appropriately changed. Moreover, the structure for compensating for the volume of the piston rod 11 entering and exiting the cylinder 1 is not limited to the gas chamber G, and can also be appropriately changed. For example, a liquid reservoir for containing liquid and gas may be provided to replace the gas chamber G, and when the buffer is extended or retracted, the liquid is exchanged between the cylinder and the liquid reservoir. In addition, the buffer D may be a double-rod type, with piston rods provided on both sides of the piston. In this case, the structure itself for compensating for the volume of the piston rod may be omitted.

[0055] Then, the liquid 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 (the side opposite to the piston rod). Figure 2 As shown, the piston 10 is a bottomed cylinder, comprising: a cylinder portion 10b with a piston ring 10a mounted on the outer periphery thereof in sliding contact with the inner periphery of the cylinder 1; and a bottom portion 10c blocking one end of the cylinder portion 10b. Figure 2 The up and down directions in are referred to as “up” and “down” for short.

[0056] The piston 10 is positioned with its bottom portion 10c facing downward and its cylindrical portion 10b facing upward. This cylindrical portion 10b is connected to a topped cylindrical housing portion 11a formed at the distal end 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 body 2 is mounted inside the guide 15, allowing it to be seated on and off the valve seat member 16 for vertical movement.

[0057] The main valve body 2 has a first valve body portion 2A and a second valve body portion 2B that can be separated into two parts, one above and the other below. An intermediate chamber L3 is formed between the main valve body 2 and the bottom 10c of the piston 10. The intermediate chamber L3 is separated from the compression-side chamber L2 by the piston 10. In addition, the bottom 10c of the piston 10 has ports 10d and 10e on the extension side and the compression side that connect the intermediate chamber L3 and the compression-side chamber L2. Furthermore, an extension-side valve 20 is stacked on the lower side of the bottom 10c, which opens and closes the outlet of the extension-side port 10d, and a compression-side valve 21 is stacked on the upper side of the bottom 10c, which opens and closes the outlet of the compression-side port 10e.

[0058] Furthermore, the inlet of the expansion-side port 10d opens into the intermediate chamber L3, and the pressure of the intermediate chamber L3 acts in a direction that opens the expansion-side valve 20. Furthermore, under the action of the pressure in the intermediate chamber L3, when the expansion-side valve 20 opens, the liquid in the intermediate chamber L3 flows into the compression-side chamber L2 through the expansion-side port 10d. Meanwhile, the inlet of the compression-side port 10e opens into the compression-side chamber L2, and the pressure of the compression-side chamber L2 acts in a direction that opens the compression-side valve 21. Furthermore, under the action of the pressure in the compression-side chamber L2, when the compression-side valve 21 opens, the liquid in the compression-side chamber L2 flows into the intermediate chamber L3 through the compression-side port 10e.

[0059] Next, as described above, the main valve body 2 includes a first valve body portion 2A and a second valve body portion 2B, which are separable in the upper and lower directions. The first valve body portion 2A is annular, and its front end is inserted into the valve seat member 16 for free movement in the axial direction, allowing it to be seated on and detached from the valve seat member 16. Meanwhile, the second valve body portion 2B includes a head portion 2a and a flange portion 2b extending outward from the lower end of the head portion 2a. Furthermore, the head portion 2a and flange portion 2b of the second valve body portion 2B each slide in contact with the inner circumference of the guide member 15, and the lower end of the second valve body portion 2B can be seated on and detached from the first valve body portion 2A.

[0060] Furthermore, the guide member 15 is formed with a through hole 15a that opens into the expansion-side chamber L1. The pressure in the expansion-side chamber L1 acts in a direction that pushes up both the first valve body portion 2A and the second valve body portion 2B, causing the first valve body portion 2A to be unseated from the valve seat member 16. Furthermore, when the first valve body portion 2A and the second valve body portion 2B move upward together and unseat from the valve seat member 16 under the action of the pressure in the expansion-side chamber L1, the liquid in the expansion-side chamber L1 flows into the intermediate chamber L3 through the gap formed between the first valve body portion 2A and the valve seat member 16.

[0061] The intermediate chamber L3 is located within the valve seat member 16, the first valve body 2A, and the inner circumference of the cylindrical portion 10b of the piston 10. It is formed between the bottom portion 10c of the piston 10 and the second valve body 2B. The pressure in the intermediate chamber L3 acts to push the first valve body 2A downward and to push the second valve body 2B upward. In other words, the pressure in the intermediate chamber L3 acts to separate the first and second valve bodies 2A, 2B, and to remove the second valve body 2B from the first valve body 2A. Furthermore, the pressure in the intermediate chamber L3 causes the second valve body 2b to move upward and remove from the first valve body 2A. The liquid in the intermediate chamber L3 then flows into the expansion-side chamber L1 through the gap formed between the first and second valve bodies 2A, 2B, and the through-hole 15a.

[0062] In summary, in this embodiment, a main passage M is formed by the through hole 15a of the guide member 15, the intermediate chamber L3, and the expansion-side and compression-side ports 10d and 10e, respectively, connecting the expansion-side chamber L1 and the compression-side chamber L2. Furthermore, the main valve body 2 is disposed in the main passage M, and the expansion-side valve 20 and the compression-side valve 21 are disposed in series with the main valve body 2.

[0063] Next, a back-pressure chamber L4 is formed on the upper surface of the flange portion 2b, which serves as the backside of the main valve body 2. The pressure in this back-pressure chamber L4 acts in a direction that pushes the second valve body 2B downward along with the first valve body 2A. Furthermore, the second valve body 2B is provided with a pressure introduction passage p1, which has a throttle O midway through it and reduces the pressure in the expansion-side chamber L1 before introducing it into the back-pressure chamber L4; a pressure control passage p2, which is connected to the pressure introduction passage p1 downstream of the throttle O; and a pressure-reducing passage p3, which allows liquid to flow only from the intermediate chamber L3 into the back-pressure chamber L4 and reduces the pressure in the intermediate chamber L3 before introducing it into the back-pressure chamber L4.

[0064] Furthermore, a solenoid valve V including a solenoid S1 according to this embodiment is disposed midway along the pressure control passage p2. This solenoid valve V comprises a valve element 3, which serves as a valve body that opens and closes the pressure control passage p2 by seating or releasing on a valve seat 22 provided on the second valve body portion 2B; and a solenoid S1, which applies a downward thrust to the valve element 3. When the valve element 3 moves downward under the thrust of the solenoid S1, it seats on the valve seat 22, thereby closing the pressure control passage p2. Thus, the thrust of the solenoid S1 acts in a direction that closes the valve element 3.

[0065] Meanwhile, the pressure in the back-pressure chamber L4 acts to push the valve core 3 upward. When the pressure in the back-pressure chamber L4 increases, the upward force generated by this pressure overcomes the downward force generated by the solenoid S1 and other components, causing the valve core 3 to move upward, unseating from the valve seat 22 and opening the pressure control passage p2. In other words, when the pressure in the back-pressure chamber L4 acts to open the valve core 3 and reaches the valve-opening pressure of the valve core 3, the valve core 3 opens the pressure control passage p2. This action of the valve core 3 seating or unseating on the valve seat 22, opening and closing the pressure control passage p2, is also referred to as the opening and closing of the solenoid valve V.

[0066] Furthermore, in this embodiment, when the solenoid valve V is open, the liquid in the backpressure chamber L4 flows through the pressure control passage p2 into the upper gap L5 formed between the head portion 2a of the second valve body portion 2B and the solenoid S1. This upper gap L5 communicates with the intermediate chamber L3 via a connecting passage p4 formed in the second valve body portion 2B. Thus, when the solenoid valve V is open, the liquid flows from the backpressure chamber L4 into the upper gap L5 via the pressure control passage p2, and then from the upper gap L5 into the intermediate chamber L3 via the connecting passage p4. Consequently, the connecting passage p4 keeps the pressure in the upper gap L5 and the pressure in the intermediate chamber L3 approximately the same.

[0067] Next, the solenoid S1 involved in this embodiment includes: a coil 4, which is axially accommodated in the housing portion 11a of the piston rod 11; a first fixed iron core 5, which is arranged on the upper side of the coil 4; a second fixed iron core 6, which is arranged on the lower side of the coil 4 with a gap between it and the first fixed iron core 5; a first movable iron core 7 and a second movable iron core 8, which are arranged to be movable up and down between the first fixed iron core 5 and the second fixed iron core 6; a spring 9, which applies downward force to the first movable iron core 7; a leaf spring 90, which limits the downward movement of the first movable iron core 7 relative to the second movable iron core 8; and a leaf spring 91, which limits the downward movement of the second movable iron core 8.

[0068] Here, the direction along the centerline passing through the center of the coil 4 is the axial direction of the coil 4, and the "up" and "down" here refer to both axial directions of the coil 4. Therefore, it can be said that the first fixed iron core 5 is arranged on one axial end side of the coil 4, and the second fixed iron core 6 is arranged on the other axial end side of the coil 4. Furthermore, it can be said that the spring 9 applies force to the first movable iron core 7 toward the second fixed iron core 6, the leaf spring 90 functions as a restricting portion that restricts movement of the first movable iron core 7 relative to the second movable iron core 8 toward the second fixed iron core 6, and the leaf spring 91 functions as a restricting portion that restricts movement of the second movable iron core 8 toward the second fixed iron core 6.

[0069] Hereinafter, each component constituting the solenoid S1 according to this embodiment will be described in detail.

[0070] The coil 4 is integrally molded with a wiring harness 40 for energizing it, formed by molded resin. This wiring harness 40 extends from the inside of the piston rod 11 to the outside of the shock absorber D and is connected to a power source. Furthermore, the first fixed core 5, second fixed core 6, first movable core 7, and second movable core 8 are each formed of a magnetic material. When energized, the coil 4 generates magnetic flux, which flows through the first fixed core 5, first movable core 7, second movable core 8, second fixed core 6, and housing 11a. This magnetic flux attracts the first movable core 7 upward toward the first fixed core 5, and the second movable core 8 downward toward the second fixed core 6.

[0071] An annular filling ring 41 made of a non-magnetic material is installed between the first fixed core 5 and the second fixed core 6. This filling ring 41 forms a magnetic gap between the first and second fixed cores 5 and 6. Furthermore, a first movable core 7 and a second movable core 8 are arranged inside this filling ring 41. Both the first and second movable cores 7 and 8 are cylindrical with bottoms. The first movable core 7 is inserted into the inside of the second movable core 8 so that it can move vertically (axially), and the second movable core 8 is inserted into the inside of the filling ring 41 so that it can move vertically (axially).

[0072] like Figure 3 As shown, the outer cylinder, or second movable iron core 8, includes an outer bottom portion 8a and an outer cylinder portion 8b extending from the outer periphery of the outer bottom portion 8a. With the outer bottom portion 8a facing downward (toward the second fixed iron core 6), the outer cylinder portion 8b is brought into sliding contact with the inner periphery of the packing ring 41. Meanwhile, the first movable iron core 7, or inner cylinder, includes an inner bottom portion 7a, an inner cylinder portion 7b extending from the outer periphery of the inner bottom portion 7a, and an annular guide portion 7c located around the outer periphery of the front end of the inner cylinder portion 7b. With the inner bottom portion 7a facing downward (toward the second fixed iron core 6), the inner cylinder portion 7b is inserted into the outer cylinder portion 8b, and the guide portion 7c, which protrudes upward from the outer cylinder portion 8b, is brought into sliding contact with the inner periphery of the packing ring 41.

[0073] A connecting hole 7d is formed on the inner bottom 7a of the first movable iron core 7, which passes through the thickness of the first movable iron core 7. Liquid can move in the connecting hole 7d with relatively little resistance. Therefore, the liquid will not be sealed in the upper side of the first movable iron core 7 (the side of the first fixed iron core 5), ensuring that the first movable iron core 7 moves up and down smoothly. A spring 9 is inserted into the inner side of the inner tube portion 7b of the first movable iron 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. On the other hand, the other end of the spring 9 is supported by the first fixed iron core 5, and the spring 9 applies a downward force to the first movable iron core 7.

[0074] Furthermore, the inner diameter of the outer cylindrical portion 8b of the second movable iron core 8 is larger than the outer diameter of the inner cylindrical portion 7b of the first movable iron core 7, forming an annular gap 80 between the outer cylindrical portion 8b and the inner cylindrical portion 7b. Liquid can flow through this gap 80 with relatively little resistance. Furthermore, a communication hole 8c extending through the thickness of the outer bottom portion 8a of the second movable iron core 8 is formed, allowing liquid to flow through this communication hole 8c with relatively little resistance. Therefore, while the volume of the space L6 formed above the front end of the outer cylindrical portion 8b (on the first fixed iron core 5 side) and the space L7 formed between the outer bottom portion 8a and the inner bottom portion 7a changes as the second movable iron core 8 moves up and down, the liquid still flows between the spaces L6 and L7 through the gap 80 and moves up and down the outer bottom portion 8a through the communication hole 8c.

[0075] Thus, in this embodiment, a communication passage p5 is formed by the communication hole 8c formed in the outer bottom portion 8a of the second movable iron core 8, connecting the upper and lower parts of the second movable iron core 8 (the first fixed iron core 5 side and the second fixed iron core 6 side). Furthermore, the space L6 formed on the upper front end of the outer cylindrical portion 8b (the first fixed iron core 5 side) is connected to the communication passage p5 via the gap 80 formed between the outer cylindrical portion 8b and the inner cylindrical portion 7b. Therefore, when the second movable iron core 8 moves, the flow of liquid in and out of the spaces L6 and L7 can be compensated for the increase or decrease in volume, thereby suppressing the generation of a damping force that would hinder the movement of the second movable iron core 8, thereby ensuring smooth vertical movement of the second movable iron core 8.

[0076] Next, leaf springs 90 and 91, which function as the aforementioned restricting portions, are arranged above and below the outer bottom portion 8a of the second movable iron core 8. More specifically, the first restricting portion, i.e., the upper leaf spring 90, is positioned between the outer bottom portion 8a of the second movable iron core 8 and the inner bottom portion 7a of the first movable iron core 7, which is located above and below it. The second restricting portion, i.e., the lower leaf spring 91, is positioned between the outer bottom portion 8a of the second movable iron core 8 and the inner bottom portion 7a of the first movable iron core 7, which is located above and below it.

[0077] Furthermore, the upper leaf spring 90 includes an annular plate-shaped seat laminated on the outer bottom portion 8a of the second movable iron core 8, and multiple legs extending radially outward from this seat and obliquely rising upward. Meanwhile, the lower leaf spring 91 includes an annular seat laminated on the second fixed iron core 6, and multiple legs extending inward from this seat and obliquely rising upward. Thus, each of the upper and lower leaf springs 90 and 91 includes multiple legs, and gaps are formed between adjacent legs, so that the leaf springs 90 and 91 do not obstruct the flow of liquid.

[0078] Furthermore, when the first movable iron core 7 moves downward relative to the second movable iron core 8, the inner bottom 7a of the first movable iron core 7 abuts against the leaf spring 90. Thus, the downward movement of the first movable iron core 7 relative to the second movable iron core 8 is restricted, and the first movable iron core 7 and the second movable iron core 8 then move downward as one. Furthermore, when the second movable iron core 8 moves downward, the outer bottom 8a of the second movable iron core 8 abuts against the leaf spring 91, compressing it and preventing it from moving downward.

[0079] A through hole is formed in the center portion of the second fixed iron core 6, and the shaft portion 3a of the valve core 3 can be freely moved through the through hole. Moreover, the front end of the shaft portion 3a abuts against the outer bottom 8a of the second movable iron core 8. Therefore, when the power to the coil 4 is disconnected, the first movable iron core 7 is urged downward by the spring 9 and abuts against the second movable iron core 8 via the leaf spring 90, so that the valve core 3 is subjected to a downward force generated by the force of the spring 9. In contrast, when the coil 4 is energized to attract the first movable iron core 7 to the first fixed iron core 5 and the second movable iron core 8 to the second fixed iron core 6, although the spring 9 is compressed by the first movable iron core 7 and its force is not transmitted to the valve core 3, the valve core 3 is subjected to a downward force generated by the force that attracts the second movable iron core 8.

[0080] Furthermore, the first restricting portion, i.e., the leaf spring 90, restricts the proximity of the inner bottom portion 7a of the first movable iron core 7 and the outer bottom portion 8a of the second movable iron core 8, which is vertically (axially) opposed thereto, thereby preventing the first movable iron core 7 and the second movable iron core 8 from being attracted to each other when power is supplied to the coil 4. Similarly, the second restricting portion, i.e., the leaf spring 91, restricts the proximity of the outer bottom portion 8a of the second movable iron core 8 and the second fixed iron core 6, which is vertically (axially) opposed thereto, thereby preventing the second movable iron core 8 from being attracted to the second fixed iron core 6 when power is supplied to the coil 4.

[0081] Furthermore, the first and second limiting portions are not limited to the leaf springs 90 and 91, but may also be rings or sheets of non-magnetic materials such as rubber, synthetic resin, or aluminum. In this case, the rings or sheets may be positioned on the outer periphery of the inlet and outlet of the communicating holes 7d and 8c, for example, to avoid obstructing the flow of the liquid. Furthermore, as long as they do not obstruct 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 when power is applied, the first and second limiting portions may also be magnetic. Alternatively, a portion of the first movable core 7 or the second movable core 8 may function as the first limiting portion, or a portion of the second movable core 8 or the second fixed core 6 may function as the second limiting portion.

[0082] On the other hand, no restriction is provided between the first fixed core 5 and the first movable core 7. Therefore, when the coil 4 is energized, the first movable core 7 is attracted to the first fixed core 5. Thus, if the first movable core 7 is attracted to the first fixed core 5 when the coil 4 is energized, the first movable core 7 can be stably maintained in this position, where the first movable core 7 compresses the spring 9 without transmitting the spring 9's force to the second movable core 8. However, the first movable core 7 does not necessarily need to be attracted to the first fixed core 5 when the coil 4 is energized.

[0083] then, Figure 4 The relationship between the amount of current supplied to the solenoid S1 and the force applied by the solenoid S1 to the valve element 3 is shown. Figure 4 Here, Ia is the minimum current required to attract the first movable iron core 7, which is away from the first fixed iron core 5, to the first fixed iron core 5, and Ib is the minimum current required to maintain the attracted state of the first fixed iron core 5 and the first movable iron core 7 after the first movable iron core 7 is attracted to the first fixed iron core 5. Ic will be described below.

[0084] First, when the current supplied to coil 4 is zero—that is, when solenoid S1 is de-energized—the first movable iron core 7 is pressed downward by the force of spring 9 and abuts against the second movable iron core 8 via leaf spring 90. This forces the second movable iron core 8 downward along with the valve core 3. Thus, when solenoid S1 is de-energized, the valve core 3 is subjected to the downward force generated by spring 9 through the second movable iron core 8, leaf spring 90, and first movable iron core 7. In other words, when solenoid S1 is de-energized, the solenoid S1 applies the downward force generated by spring 9 to the valve core 3.

[0085] Next, when the current supplied to solenoid S1 increases, the upward force pulling the first movable iron core 7 toward the first fixed iron core 5 increases, and the downward force pulling the second movable iron core 8 toward the second fixed iron core 6 also increases. In this case, in the range where the current supplied to solenoid S1 is less than Ia, although the force of spring 9 is transmitted to valve core 3, part of the force of spring 9 that biases the first movable iron core 7 downward is offset by the force pulling the first movable iron core 7 upward (toward the first fixed iron core 5). Therefore, in the range where the current is less than Ia, the greater the current supplied to solenoid S1, the smaller the downward force exerted by solenoid S1 on valve core 3.

[0086] On the other hand, in a case where the amount of current supplied to the solenoid S1 is increased, in a region where the amount of current is Ia or more, the first movable iron core 7 is attracted to the first fixed iron core 5 against the force of the spring 9 and is adsorbed. In this state, the force of the spring 9 is not transmitted to the second movable iron core 8, and only the force to attract the second movable iron core 8 to the second fixed iron core 6 acts in the direction to press down the spool 3. The downward force to attract the second movable iron core 8 increases in proportion to the amount of current supplied to the solenoid S1, and therefore, in the region where the amount of current supplied to the solenoid S1 is Ia or more, the greater the amount of current supplied to the solenoid S1, the greater the force with which the solenoid S1 applies to the spool 3 in proportion to the amount of current.

[0087] On the other hand, in a case where the amount of current supplied to the solenoid S1 is increased, in a region where the amount of current is Ia or more, the first movable iron core 7 is attracted to the first fixed iron core 5 against the force of the spring 9 and is adsorbed. In this state, the force of the spring 9 is not transmitted to the second movable iron core 8, and only the force to attract the second movable iron core 8 to the second fixed iron core 6 acts in the direction to press down the spool 3. The downward force to attract the second movable iron core 8 increases in proportion to the amount of current supplied to the solenoid S1, and therefore, in the region where the amount of current supplied to the solenoid S1 is Ia or more, the greater the amount of current supplied to the solenoid S1, the greater the force with which the solenoid S1 applies to the spool 3 in proportion to the amount of current.

[0088] On the other hand, in a case where the amount of current supplied to the solenoid S1 is increased, in a region where the amount of current is Ia or more, the first movable iron core 7 is attracted to the first fixed iron core 5 against the force of the spring 9 and is adsorbed. In this state, the force of the spring 9 is not transmitted to the second movable iron core 8, and only the force to attract the second movable iron core 8 to the second fixed iron core 6 acts in the direction to press down the spool 3. The downward force to attract the second movable iron core 8 increases in proportion to the amount of current supplied to the solenoid S1, and therefore, in the region where the amount of current supplied to the solenoid S1 is Ia or more, the greater the amount of current supplied to the solenoid S1, the greater the force with which the solenoid S1 applies to the spool 3 in proportion to the amount of current.

[0089] From Figure 4 It can also be seen that the minimum amount of current required to maintain the adsorption of the first movable iron core 7 to the first fixed iron core 5, that is, Ib, is smaller than the minimum amount of current required to adsorb the first movable iron core 7 in the separated state to the first fixed iron core 5, that is, Ia (Ia > Ib). Therefore, the characteristic of the force with which the solenoid S1 applies to the spool 3 with respect to the amount of current supplied to the solenoid S1 is a characteristic having hysteresis. In addition, in Figure 4 In FIG. 6, the region where the amount of current supplied to the solenoid S1 is small is exaggerated for ease of understanding.

[0090] Furthermore, in this embodiment, to control the amount of current supplied to solenoid S1 and thereby the force exerted by solenoid S1 on valve element 3, a current of at least Ia is first supplied to attract first movable core 7 to first fixed core 5. The current supplied to solenoid S1 is then controlled to a value greater than Ic, which is greater than Ib. This maintains the first movable core 7 attracted to first fixed core 5 while controlling the amount of current supplied to solenoid S1. Consequently, the current supplied to solenoid S1 is proportional to the downward force exerted by solenoid S1 on valve element 3, with the force increasing as the current supplied to solenoid S1 increases.

[0091] During normal operation (control), the force exerted by solenoid S1 on valve core 3 due to the magnetic force generated by energizing solenoid S1 is referred to as the "thrust" of solenoid S1. Specifically, the thrust of solenoid S1 can be controlled by controlling the amount of current supplied to solenoid S1. Furthermore, in this embodiment, the amount of current supplied to solenoid S1 and the thrust exerted by solenoid S1 on valve core 3 are proportional: greater current results in greater thrust, while smaller current results in less thrust.

[0092] On the other hand, when the solenoid S1 loses power, the valve core 3 is urged downward by the solenoid S1's spring 9. This force is predetermined by the spring constant and other specifications of the spring 9. Furthermore, the direction of the force applied by the spring 9 to the valve core 3 during a fault (de-energized) state is the same as the direction of the thrust applied to the valve core 3 during normal operation.

[0093] Hereinafter, the operation of the shock absorber D including the electromagnetic valve V including the solenoid S1 according to the present embodiment will be described.

[0094] When the damper D extends, the piston 10 moves upward within the cylinder 1, compressing the expansion-side chamber L1. As the pressure in the expansion-side chamber L1 rises, the fluid in the expansion-side chamber L1 flows through the pressure introduction passage p1 into the back-pressure chamber L4, increasing the pressure in the back-pressure chamber L4. Then, when the pressure in the back-pressure chamber L4 reaches the valve opening pressure of the valve element 3, the valve element 3 (solenoid valve V) opens, and the fluid in the back-pressure chamber L4 flows through the pressure control passage p2, the upper clearance L5, and the connecting passage p4 into the intermediate chamber L3. Therefore, when the damper D extends, the pressure in the back-pressure chamber L4 is controlled to the valve opening pressure of the solenoid valve V.

[0095] Further, when the pressure or the like acting on the extension side chamber LI of the first valve body portion 2A and the second valve body portion 2B exceeds the pressure or the like of the back pressure chamber L4, 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, the liquid of the extension side chamber LI moves to the intermediate chamber L3 through the gap, and the liquid of the intermediate chamber L3 opens the extension side valve 20 to move to the compression side chamber L2.

[0096] Thus, when the damper D extends, the first valve body portion 2A in the main valve body 2 and the extension side valve 20 are opened, and the liquid flowing from the extension side chamber LI to the compression side chamber L2 in the main passage M is resisted by the main valve body 2 and the extension side valve 20. Therefore, when the damper D extends, the pressure in the extension side chamber LI rises, and the damper D generates the extension side damping force that hinders the extension operation thereof.

[0097] Further, when the amount of current supplied to the solenoid S1 is controlled normally, the greater the amount of current supplied to the solenoid S1, the greater the downward (closing direction) pushing force of the solenoid S1 on the spool 3. Therefore, the greater the amount of current supplied to the solenoid S1, the higher the opening pressure of the spool 3 (solenoid valve V), and thus the higher the pressure of the back pressure chamber L4.

[0098] Further, the pressure of the back pressure chamber L4 pushes the second valve body portion 2B and the first valve body portion 2A downward (closing direction), and thus the greater the amount of current supplied to the solenoid S1, the higher the pressure of the back pressure chamber L4, the higher the opening pressure of the first valve body portion 2A in the main valve body 2, and the greater the generated extension side damping force. Thus, during normal time, the opening pressure of the spool 3 can be adjusted by the solenoid S1, and the extension side damping force can be adjusted in size. In addition, during Figure 2 、 3 The state in which the spool 3 is opened during normal time is shown in FIG. 6.

[0099] On the other hand, when the solenoid S1 has a power failure, the opening pressure of the spool 3 (solenoid valve V) is determined depending on the force of the spring 9. Therefore, the pressure of the back pressure chamber L4 during the failure is determined depending on the specification of the spring 9, and the extension side damping force generated thereby is determined. As described above, since the force of the spring 9 is not transmitted to the spool 3 during normal time, the specification of the spring 9 can be freely set without considering the extension side damping force during normal time.

[0100] Conversely, when the damper D contracts, the piston 10 moves downward within the cylinder 1, compressing the compression-side chamber L2. As the pressure in the compression-side chamber L2 rises, the liquid in the compression-side chamber L2 opens the compression-side valve 21 and moves toward the intermediate chamber L3. Furthermore, the liquid in the intermediate chamber L3 moves toward the back-pressure chamber L4 via the pressure-reducing passage p3. At this point, the pressure in the upper clearance L5 downstream of the valve core 3 is approximately the same as that in the intermediate chamber L3, but higher than the pressure in the back-pressure chamber L4 upstream of the valve core 3. Therefore, the valve core 3 is maintained in a closed state. Furthermore, in this state, the thrust of the solenoid S1 acts downward on the second valve body 2B via the valve core 3.

[0101] Furthermore, as described above, since the pressure in the intermediate chamber L3 applies upward force only to the second valve body 2B, when the upward force generated by the pressure in the intermediate chamber L3 acting on the second valve body 2B exceeds the downward force generated by the thrust of the solenoid S1, only the second valve body 2B moves upward. This creates a gap between the second valve body 2B and the first valve body 2A, and the liquid in the intermediate chamber L3 flows through this gap into the expansion-side chamber L1.

[0102] As such, when the shock absorber D contracts, the contraction-side valve 21 and the second valve body portion 2B of the main valve body 2 open. The contraction-side valve 21 and the main valve body 2 create resistance to the liquid flowing from the contraction-side chamber L2 to the expansion-side chamber L1 in the main passage M. Consequently, when the shock absorber D contracts, the pressure in the contraction-side chamber L2 rises, and the shock absorber D generates a contraction-side damping force that hinders its contraction.

[0103] Furthermore, during normal operation, when the amount of current supplied to solenoid S1 is controlled, the greater the current supplied to solenoid S1 and the greater the thrust of solenoid S1, the greater the downward (closing) force acting on the second valve body 2B. Therefore, as the current supplied to solenoid S1 and the thrust of solenoid S1 increase, the valve-opening pressure of the second valve body 2B in the main valve body 2 increases, and the resulting damping force on the compression side increases. Thus, during normal operation, the damping force on the compression side is adjusted by adjusting the force applied downwardly by solenoid S1 via the valve element 3.

[0104] On the other hand, when the solenoid S1 fails due to power failure, the force of the spring 9 is transmitted to the second valve body portion 2B via the valve core 3. Therefore, the damping force on the compression side during a failure is also determined by the specifications of the spring 9. As described above, since the force of the spring 9 is not transmitted to the valve core 3 during normal operation, the specifications of the spring 9 can be freely set without considering the damping force on the compression side during normal operation.

[0105] Next, the effects of the solenoid S1 according to the present embodiment, the electromagnetic valve V including the solenoid S1 , and the damper D including the electromagnetic valve V including the solenoid S1 will be described.

[0106] The solenoid S1 involved in this embodiment includes: a coil 4; a first fixed iron core 5, which is located on one end side of the coil 4 in the axial direction; a second fixed iron core 6, which is located on the other end side of the coil 4 in the axial direction and has a gap with the first fixed iron core 5; a first movable iron core 7, which is arranged between the first fixed iron core 5 and the second fixed iron core 6 and is attracted by the first fixed iron core 5 when power is supplied to the coil 4; a second movable iron core 8, which is arranged between the first fixed iron core 5 and the second fixed iron core 6 and is attracted by the second fixed iron core 6 when power is supplied to the coil 4; a spring 9, which urges the first movable iron core 7 toward the second fixed iron core 6; a leaf spring (restriction part) 90, which restricts the movement of the first movable iron core 7 toward the second fixed iron core 6 relative to the second movable iron core 8; and a connecting channel p5, which connects the first fixed iron core 5 side and the second fixed iron core 6 side of the second movable iron core 8.

[0107] According to the above configuration, when the solenoid S1 is de-energized, the first movable iron core 7 is urged toward the second fixed iron core 6 by the force of the spring 9. When the movement of the first movable iron core 7 toward the second fixed iron core 6 relative to the second movable iron core 8 is restricted by the leaf spring 90, the first movable iron core 7 and the second movable iron core 8 become one, moving toward the second fixed iron core 6. Therefore, when the solenoid S1 is de-energized, the force of the spring 9 is transmitted to the second movable iron core 8 via the first movable iron core 7 and the leaf spring 90.

[0108] On the other hand, when solenoid S1 is energized, if the first movable iron core 7 is attracted by the first fixed iron core 5 and moves in the direction of attraction, the spring 9 is compressed by the first movable iron core 7, and the force of the spring 9 is not transmitted to the second movable iron core 8. Furthermore, when solenoid S1 is energized, the second movable iron core 8 is attracted by the second fixed iron core 6, and the greater the current supplied to solenoid S1, the greater the force that attracts the second movable iron core 8 toward the second fixed iron core 6.

[0109] Therefore, if the force that attracts the second movable iron core 8 is applied as thrust to an object such as the valve core 3 when the solenoid S1 is energized, the greater the current supplied to the solenoid S1, the greater the thrust applied to the object, and the smaller the current supplied to the solenoid S1, the smaller the thrust applied to the object. Furthermore, when the power is not supplied, the force of the spring 9 acts on the object via the first movable iron core 7, the leaf spring (limiting portion) 90, and the second movable iron core 8. Since the direction of the force of the spring 9 is the same as the direction of the force that attracts the second movable iron core 8 when the solenoid S1 is energized, according to the above structure, even when the solenoid S1 is not energized, it can apply force to the object in the same direction as when it is energized.

[0110] Furthermore, according to the above configuration, as described above, when the solenoid S1 is energized, if the first movable iron core 7 moves toward the first fixed iron core 5 against the force of the spring 9, the force of the spring 9 is not transmitted to the second movable iron core 8, and thus to the valve element (target) 3. Therefore, the thrust of the solenoid S1 when energized and the force applied to the target by the spring 9 when de-energized can be freely set. Furthermore, while the spring 9 is a coil spring in this embodiment, it may also be a spring other than a coil spring, such as a disc spring.

[0111] Furthermore, the solenoid S1 of this embodiment includes a communication passage p5 that connects the first fixed iron core 5 side and the second fixed iron core 6 side of the second movable iron core 8. This prevents liquid from being enclosed in spaces L6 and L7 on the first fixed iron core 5 side of the second movable iron core 8, thereby suppressing the generation of a damping force that would otherwise hinder the movement of the second movable iron core 8. Therefore, the solenoid S1 of this embodiment does not generate a damping force even when the second movable iron core 8 is moving at a high speed, allowing the second movable iron core 8 to move smoothly.

[0112] The solenoid S1 of this embodiment also includes an annular filling ring 41, which is installed between the first and second fixed cores 5 and 6. Furthermore, the second movable core 8 is a bottomed cylindrical structure, comprising an outer bottom 8a and an outer cylindrical portion 8b extending from the outer periphery of the outer bottom 8a. The outer bottom 8a is oriented toward the second fixed core 6 and inserted axially movably into the filling ring 41. Furthermore, the first movable core 7 is also a bottomed cylindrical structure, comprising an inner bottom 7a and an inner cylindrical portion 7b extending from the outer periphery of the inner bottom 7a. The inner cylindrical portion 7b is oriented toward the second fixed core 6 and inserted axially movably into the inner periphery of the outer cylindrical portion 8b of the second movable core 8. Furthermore, a spring 9 is installed between the inner bottom 7a and the first fixed core 5, with one end of the spring inserted into the inner periphery of the inner cylindrical portion 7b of the first movable core 7.

[0113] According to the above structure, when the coil 4 is excited, a magnetic circuit passes through the first fixed iron core 5, the first movable iron core 7, the second movable iron core 8, and the second fixed iron core 6, thereby attracting the first movable iron core 7 toward the first fixed iron core 5 and the second movable iron core 8 toward the second fixed iron core 6. Furthermore, while ensuring space for accommodating the spring 9 inside the first movable iron core 7, the first movable iron core 7 and the second movable iron core 8 can be miniaturized, thereby miniaturizing the solenoid S1.

[0114] Furthermore, according to the above configuration, when the first movable iron core 7 moves toward the second fixed iron core 6, the inner bottom 7a of the first movable iron core 7 approaches the outer bottom 8a of the second movable iron core 8. Therefore, if the leaf spring (restriction portion) 90 is arranged to restrict movement in the approaching direction, the movement of the first movable iron core 7 toward the second fixed iron core 6 relative to the second movable iron core 8 can be restricted. Furthermore, to achieve this arrangement, the leaf spring 90 can be easily positioned between the inner bottom 7a and the outer bottom 8a, as in the present embodiment. In other words, the above configuration makes it easy to position the leaf spring (restriction portion) 90.

[0115] Furthermore, the communication passage p5 of the solenoid S1 according to this embodiment is formed in the outer bottom portion 8a of the second movable iron core 8 and opens into the space L7 between the outer bottom portion 8a and the inner bottom portion 7a of the first movable iron core 7. Furthermore, this communication passage p5 communicates with the space L6 formed on the first fixed iron core 5 side of the outer tube portion 8b via a gap 80 formed between the outer tube portion 8b of the second movable iron core 8 and the inner tube portion 7b of the first movable iron core 7.

[0116] With this structure, the communication passage p5 prevents liquid from being enclosed on the first fixed core 5 side (space L7) of the outer bottom portion 8a of the second movable core 8. Furthermore, with this structure, the space L6 on the first fixed core 5 side of the outer cylindrical portion 8b of the second movable core 8 communicates with the space L7 via the gap 80. Therefore, even when the second movable core 8 is slidably inserted into the filling ring 41 as in this embodiment, liquid is prevented from being enclosed in the space L6. Therefore, with this structure, the generation of a damping force that would hinder the movement of the second movable core 8 can be reliably suppressed, ensuring smooth vertical movement of the second movable core 8.

[0117] Furthermore, the first movable iron core 7 of the solenoid S1 according to this embodiment includes a guide portion 7c located on the outer periphery of the distal end of the inner cylindrical portion 7b, which protrudes outward from the outer cylindrical portion 8b of the second movable iron core 8. This guide portion 7c is in sliding contact with the inner periphery of the filling ring 41. Furthermore, the outer diameter of the inner cylindrical portion 7b is smaller than the inner diameter of the outer cylindrical portion 8b. This creates an annular gap 80 between the inner cylindrical portion 7b and the outer cylindrical portion 8b, increasing the flow path area. Furthermore, even if the outer diameter of the inner cylindrical portion 7b is smaller than the inner diameter of the outer cylindrical portion 8b, the guide portion 7c of the first movable iron core 7 is supported by the filling ring 41, thereby suppressing radial displacement of the first movable iron core 7.

[0118] However, the structure for preventing liquid from being sealed into the first fixed iron core 5 side of the second movable iron core 8 is not limited to this and can be modified as appropriate. For example, a groove arranged in the axial direction can be formed on the outer periphery of the inner cylindrical portion 7b of the first movable iron core 7 or the inner periphery of the outer cylindrical portion 8b of the second movable iron core 8, and the gap 80 is formed between the inner cylindrical portion 7b and the outer cylindrical portion 8b by the groove. Figure 5 、 6 A further modified example of the structure for preventing the liquid from being sealed in the first fixed iron core 5 side of the second movable iron core 8 is shown. Hereinafter, each modified example of the solenoid S1 according to the present embodiment will be described in detail.

[0119] In the first modified example of the solenoid S1 of this embodiment, as shown in FIG. Figure 5 As shown, the connecting channel p5 is formed at the outer bottom 8a of the second movable iron core 8, opens between the outer bottom 8a and the inner bottom 7a of the first movable iron core 7 (space L7), and is connected to the space L6 on the side of the first fixed iron core 5 formed in the outer tube portion 8b of the second movable iron core 8 via the connecting hole 7d formed in the inner bottom 7a and the gap 70 formed between the front end of the inner tube portion 7b and the first fixed iron core 5.

[0120] Even in this structure, the communication passage p5 prevents liquid from being enclosed on the first fixed core 5 side (space L7) of the outer bottom portion 8a of the second movable core 8. Furthermore, in this structure, since the space L6 on the first fixed core 5 side of the outer cylindrical portion 8b of the second movable core 8 communicates with the space L7 via the gap 70 and the communication hole 7d, liquid is prevented from being enclosed in the space L6 even when the second movable core 8 is slidably inserted into the inner side of the filling ring 41 and the first movable core 7 is slidably inserted into the inner side of the outer cylindrical portion 8b of the second movable core 8. Therefore, in this structure, the generation of a damping force that would hinder the movement of the second movable core 8 can be reliably suppressed, ensuring smooth vertical movement of the second movable core 8.

[0121] in addition, Figure 5 In the embodiment, a radially extending groove is formed at the front end of the inner cylindrical portion 7b of the first movable core 7. This groove forms a gap 70 between the inner cylindrical portion 7b and the first fixed core 5. However, the gap 70 may also be formed by a groove formed in the first fixed core 5.

[0122] Next, in the second modified example of the solenoid S1 of this embodiment, there are two communication paths connecting the first fixed iron core 5 side and the second fixed iron core 6 side of the second movable iron core 8. Figure 6As shown, the first passage, i.e., the first communication passage p5a, is formed at the outer bottom portion 8a of the second movable iron core 8, and opens at the space L7 between the outer bottom portion 8a and the inner bottom portion 7a. On the other hand, the second passage, i.e., the second communication passage p5b, is formed between the second movable iron core 8 and the packing ring 41.

[0123] In the above structure, the liquid can be prevented from being trapped at the first fixed iron core 5 side (the space L7) of the outer bottom portion 8a of the second movable iron core 8 by the first communication passage p5a, and the liquid can be prevented from being trapped at the first fixed iron core 5 side (the space L6) of the outer cylindrical portion 8b of the second movable iron core 8 by the second communication passage p5b. Therefore, in the above structure, the generation of the damping force that hinders the movement of the second movable iron core 8 can be surely suppressed, and the smooth up-and-down movement of the second movable iron core 8 can be ensured.

[0124] Further, in the present embodiment, the second communication passage p5b is formed by a gap formed between the second movable iron core 8 and the packing ring 41 by a groove formed in the outer periphery of the second movable iron core 8 in the axial direction. However, the structure for forming the gap between the second movable iron core 8 and the packing ring 41 can be appropriately changed. For example, a groove provided in the axial direction can be formed in the inner periphery of the packing ring 41, or the outer diameter of the second movable iron core 8 can be made smaller than the inner diameter of the packing ring 41.

[0125] Further, the solenoid S1 involved in the present embodiment constitutes an electromagnetic valve V together with the spool (valve body) 3 that opens and closes the pressure control passage p2. Moreover, the solenoid S1 applies, in the direction of closing the pressure control passage p2, the force that attracts the second movable iron core 8 to the second fixed iron core 6 side when the coil 4 is energized to the spool (valve body) 3. Therefore, by changing the amount of current supplied to the solenoid S1, the opening pressure of the electromagnetic valve V can be adjusted, and the pressure on the upstream side of the electromagnetic valve V can be set to the opening pressure of the electromagnetic valve V.

[0126] Further, as described above, in the solenoid S1 of the present embodiment, the greater the amount of current supplied at the time of energization, the greater the thrust applied to the target object. Therefore, in the electromagnetic valve V provided with the solenoid S1 of the present embodiment, the greater the amount of current supplied to the solenoid S1, the higher the opening pressure of the spool 3 can be made. Further, as described above, in the solenoid S1 of the present embodiment, the spring 9 can apply a force to the target object in the same direction as the thrust at the time of energization even at the time of non-energization. Thus, in the electromagnetic valve V provided with the solenoid S1 of the present embodiment, the opening pressure at the time of non-energization can be determined in accordance with the specifications of the spring 9.

[0127] Furthermore, a solenoid valve V including the solenoid S1 of this embodiment is provided in a damper D. In addition to the solenoid valve V, the damper D further comprises: a cylinder 1; a piston rod 11 axially movably inserted into the cylinder 1; a main passage M through which fluid flows when the cylinder 1 and the piston rod 11 move relative to each other in the axial direction; a main valve body 2 that opens and closes the main passage M; a pressure introduction passage p1 provided with a throttle O midway, which reduces the pressure upstream of the main valve body 2 in the main passage M to the rear surface of the main valve body 2; and a pressure control passage p2 connected to the pressure introduction passage p1 downstream of the throttle O and provided with the aforementioned solenoid valve V.

[0128] According to the above structure, when the cylinder 1 and piston rod 11 move relative to each other in the axial direction, the main valve body 2 exerts resistance on the flow of fluid through the main passage M, generating a damping force due to this resistance. Furthermore, since the back pressure of the main valve body 2 is set to the valve-opening pressure of the solenoid valve V, the back pressure of the main valve body 2 can be adjusted by varying the amount of current supplied to the solenoid S1. Furthermore, as the back pressure of the main valve body 2 increases, the first valve body portion 2A of the main valve body 2 becomes more difficult to open, resulting in a greater expansion-side damping force. Therefore, according to the above structure, the magnitude of the expansion-side damping force generated can be adjusted by varying the amount of current supplied to the solenoid S1.

[0129] Furthermore, as described above, in the solenoid valve V including the solenoid S1 of the present embodiment, the greater the amount of current supplied to the solenoid S1, the higher the valve opening pressure of the solenoid valve V. Therefore, in the shock absorber D including the solenoid valve V including the solenoid S1 of the present 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 damping force on the expansion side can be generated.

[0130] Specifically, in the shock absorber D, since the generated extension-side damping force is reduced when the current supplied to the solenoid S1 is low, when the shock absorber D is used in a vehicle suspension, power consumption during normal driving can be reduced. Furthermore, this suppresses heat generation in the solenoid S1, minimizing temperature fluctuations in the shock absorber D. This reduces changes in the damping force characteristics (damping force characteristics relative to piston velocity) caused by changes in fluid temperature.

[0131] As described above, in the solenoid valve V including the solenoid S1 of this embodiment, the valve opening pressure when de-energized can be determined by the specifications of the spring 9. Therefore, in a shock absorber D including 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. Consequently, even in the event of a power failure of the solenoid S1, insufficient damping force on the extension side can be prevented. Furthermore, in the shock absorber D, the pressure control passage p2 can be provided as a passage connected to the backpressure chamber L4 and used to set the backpressure of the main valve body 2. This eliminates the need to switch the passage connected to the backpressure chamber L4 between energized and de-energized solenoid S1. This reduces the structural complexity of the shock absorber D and reduces costs.

[0132] Furthermore, in this embodiment, the back pressure of the main valve body 2 is controlled by the solenoid valve V only when the damper D is extended. During contraction, the thrust of the solenoid S1 in the solenoid valve V directly acts on the main valve body 2 in the closing direction. However, it is of course also possible to control the back pressure of the main valve body by the solenoid valve V during contraction of the damper D.

[0133] Furthermore, the rod that enters and exits the cylinder 1 does not necessarily need to be a piston rod equipped with a piston, and the location of the main valve body for controlling back pressure using the solenoid valve V is not limited to the piston portion. For example, in the case of a shock absorber equipped with a reservoir as described above, the passage connecting the expansion-side chamber or the compression-side chamber with the reservoir can be used as the main passage, a main valve body can be provided, and back pressure on the main valve body can be controlled using the solenoid valve V. Furthermore, in the case of a unidirectional shock absorber in which liquid circulates unidirectionally through the expansion-side chamber, reservoir, and compression-side chamber in this order during expansion and contraction, the circulation passage connecting the expansion-side chamber and the reservoir can be used as the main passage, a main valve body can be provided, and back pressure on the main valve body can be controlled using the solenoid valve V.

[0134] <Second embodiment>

[0135] Next, explain Figure 7 The solenoid S2 of the second embodiment of the present invention is shown in FIG. The solenoid S2 of this embodiment is used in the same electromagnetic valve as the solenoid S1 of the first embodiment. Figure 2 The solenoid S1 of the first embodiment is directly replaced with the solenoid S2 of this embodiment. The basic structure of the solenoid S2 of this embodiment is the same as that of the solenoid S1 of the first embodiment, and the common structures are denoted by the same reference numerals and detailed descriptions are omitted.

[0136] The major difference between the solenoid S2 of this embodiment and the solenoid S1 of the first embodiment lies in the reversed placement of the first and second movable iron cores. More specifically, in this embodiment, the first movable iron core 7A comprises an inner cylindrical portion 7e and an outer cylindrical portion 7f, arranged in two layers; a connecting portion 7g connecting these portions at one axial end; and an inner bottom portion 7h at the other end of the inner cylindrical portion 7e. With the inner bottom portion 7h facing downward (toward the second fixed iron core 6), the outer cylindrical portion 7f is in sliding contact with the inner circumference of the filling ring 41. Meanwhile, the second movable iron core 8A is a bottomed cylindrical shape with an outer bottom portion 8d and an intermediate cylindrical portion 8e extending from the outer periphery of the outer bottom portion 8d. With the outer bottom portion 8d facing downward (toward the second fixed iron core 6), the intermediate cylindrical portion 8e is in sliding contact with the inner circumference of the outer cylindrical portion 7f of the first movable iron core 7A.

[0137] A connecting hole 7i is formed on the inner bottom 7h of the first movable iron core 7A, which penetrates the thickness thereof, and the liquid can move in the connecting hole 7i relatively without resistance. As a result, the liquid will not be sealed in the upper side of the first movable iron core 7A (the side of the first fixed iron core 5), ensuring that the first movable iron core 7A moves up and down smoothly. A spring 9 is inserted into the inner side of the inner tube portion 7e of the first movable iron core 7A. Even in this embodiment, the spring 9 is a coil spring, and one end of the spring 9 abuts against the inner bottom 7h. On the other hand, the other end of the spring 9 is supported by the first fixed iron core 5, and the spring 9 applies a downward force to the first movable iron core 7A.

[0138] Furthermore, a connecting hole 8f is formed on the outer bottom 8d of the second movable iron core 8A, extending through its thickness. Liquid can flow through this connecting hole 8f with relatively little resistance. Furthermore, the inner diameter of the intermediate cylindrical portion 8e of the second movable iron core 8A is larger than the outer diameter of the inner cylindrical portion 7e of the first movable iron core 7A, forming an annular gap 81 between the intermediate cylindrical portion 8e and the inner cylindrical portion 7e. Therefore, the space L8 formed on the upper side of the front end of the intermediate cylindrical portion 8e (on the side of the first fixed iron core 5) and the space L9 formed between the outer bottom 8d and the inner bottom 7a form a continuous space. Furthermore, although the volume of this continuous space changes as the second movable iron core 8A moves up and down, liquid can still flow in and out of this space through the connecting hole 8f.

[0139] Thus, in this embodiment, a continuous space is formed between the upper side of the second movable core 8A (on the first fixed core 5 side), that is, the second movable core 8A and the first movable core 7A, via the gap 81. Furthermore, a connecting hole 8f formed in the outer bottom 8d of the second movable core 8A forms a communication passage p5 that opens this space to the lower side of the second movable core 8A (on the second fixed core 6 side). Therefore, when the second movable core 8A moves, the flow of liquid in and out of this space can be compensated for the increase or decrease in volume, thereby suppressing the generation of a damping force that would otherwise hinder the movement of the second movable core 8A, thereby ensuring smooth vertical movement of the second movable core 8A.

[0140] Next, in this embodiment, leaf springs 90 and 91 are arranged above and below the outer bottom 8d of the second movable iron core 8A, functioning as restricting portions. More specifically, the first restricting portion, or upper leaf spring 90, is positioned between the outer bottom 8d of the second movable iron core 8A and the inner bottom 7h of the first movable iron core 7A, which is located above and below it. The second restricting portion, or lower leaf spring 91, is positioned between the outer bottom 8a of the second movable iron core 8A and the second fixed iron core 6, which is located above and below it.

[0141] Furthermore, when the first movable iron core 7A moves downward relative to the second movable iron core 8A, the inner bottom 7h of the first movable iron core 7A abuts against the leaf spring 90. Thus, the downward movement of the first movable iron core 7A relative to the second movable iron core 8A is restricted, and the first movable iron core 7A and the second movable iron core 8A then move downward as one. Furthermore, when the second movable iron core 8A moves downward, the outer bottom 8d of the second movable iron core 8A abuts against the leaf spring 91, compressing it and preventing it from moving downward.

[0142] Furthermore, a through hole is formed in the center portion of the second fixed iron core 6, and the shaft portion 3a of the valve core 3 can be freely inserted into the through hole. Moreover, the front end of the shaft portion 3a abuts the outer bottom 8d of the second movable iron core 8A. Therefore, when the power to the coil is disconnected, the first movable iron core 7A is urged downward by the spring 9 and abuts against the second movable iron core 8A via the leaf spring 90, so that the valve core 3 is subjected to the downward force generated by the force of the spring 9. In contrast, when the coil is energized to attract the first movable iron core 7A toward the first fixed iron core 5 and the second movable iron core 8A toward the second fixed iron core 6, although the spring 9 is compressed by the first movable iron core 7A and its force is not transmitted to the valve core 3, the valve core 3 is subjected to the downward force generated by the force attracting the second movable iron core 8A.

[0143] Furthermore, the first restricting portion, i.e., the leaf spring 90, restricts the proximity of the inner bottom 7h of the first movable iron core 7A and the outer bottom 8d of the second movable iron core 8A, which is vertically (axially) opposed thereto, thereby preventing the first movable iron core 7A and the second movable iron core 8A from adhering to each other when power is supplied to the coil. Similarly, the second restricting portion, i.e., the leaf spring 91, restricts the proximity of the outer bottom 8d of the second movable iron core 8A and the second fixed iron core 6, which is vertically (axially) opposed thereto, thereby preventing the second movable iron core 8A from adhering to the second fixed iron core 6 when power is supplied to the coil. The first and second restricting portions are not limited to the leaf springs 90 and 91, respectively, and may be modified in the same manner as in the first embodiment.

[0144] On the other hand, there is no restriction between the first fixed core 5 and the first movable core 7A, so the first movable core 7A is attracted to the first fixed core 5 when the coil is energized. This allows the first movable core 7A to be attracted to the first fixed core 5 when the coil is energized, maintaining a stable position. In this position, the first movable core 7A compresses the spring 9, and the force of the spring 9 is not transmitted to the second movable core 8A. However, the first movable core 7A does not necessarily need to be attracted to the first fixed core 5 when the coil 4 is energized.

[0145] The relationship between the amount of current supplied to the solenoid S2 according to this embodiment and the force applied by the solenoid S2 to the valve element (target) 3 is the same as that of the solenoid S1 according to the first embodiment. Figure 4 The operation of the shock absorber including the electromagnetic valve including the solenoid S2 according to this embodiment is also the same as the operation of the shock absorber D including the electromagnetic valve V including the solenoid S1 according to the first embodiment.

[0146] The following describes the effects of the solenoid S2 according to this embodiment. While the same structure as the solenoid S1 according to the first embodiment naturally exhibits the same effects, detailed explanations are omitted here. Furthermore, the effects of the solenoid valve and the damper including the solenoid valve according to this embodiment are similar to those of the solenoid S1, the solenoid valve V including the solenoid S1, and the damper D including the solenoid valve V according to the first embodiment, and therefore detailed explanations are omitted here.

[0147] The solenoid S2 involved in this embodiment includes: a coil; a first fixed iron core 5, which is located on one end side of the coil in the axial direction; a second fixed iron core 6, which is located on the other end side of the coil in the axial direction and has a gap with the first fixed iron core 5; a first movable iron core 7A, which is arranged between the first fixed iron core 5 and the second fixed iron core 6 and is attracted by the first fixed iron core 5 when the coil is energized; a second movable iron core 8A, which is arranged between the first fixed iron core 5 and the second fixed iron core 6 and is attracted by the second fixed iron core 6 when the coil is energized; a spring 9, which urges the first movable iron core 7A toward the second fixed iron core 6; a leaf spring (restriction portion) 90, which restricts the movement of the first movable iron core 7A toward the second fixed iron core 6 relative to the second movable iron core 8A; and a connecting channel p5, which connects the first fixed iron core 5 side and the second fixed iron core 6 side of the second movable iron core 8A.

[0148] According to the above configuration, when the solenoid S2 is de-energized, the first movable iron core 7A is urged toward the second fixed iron core 6 by the force of the spring 9. When the movement of the first movable iron core 7A toward the second fixed iron core 6 relative to the second movable iron core 8A is restricted by the leaf spring 90, the first movable iron core 7A and the second movable iron core 8A become one, moving toward the second fixed iron core 6. Therefore, when the solenoid S2 is de-energized, the force of the spring 9 is transmitted to the second movable iron core 8A via the first movable iron core 7A and the leaf spring 90.

[0149] On the other hand, when solenoid S2 is energized, if the first movable iron core 7A is attracted by the first fixed iron core 5 and moves in the direction of attraction, the spring 9 is compressed by the first movable iron core 7A, and the force of the spring 9 is not transmitted to the second movable iron core 8A. Furthermore, when solenoid S2 is energized, the second movable iron core 8A is attracted by the second fixed iron core 6, and the greater the current supplied to solenoid S2, the greater the force that attracts the second movable iron core 8A toward the second fixed iron core 6.

[0150] Therefore, if the force that attracts the second movable iron core 8A is applied as thrust to an object such as the valve core 3 when the solenoid S2 is energized, the greater the amount of current supplied to the solenoid S2, the greater the thrust applied to the object, and the smaller the amount of current supplied to the solenoid S2, the smaller the thrust applied to the object. Furthermore, when the power is not supplied, the force of the spring 9 acts on the object via the first movable iron core 7A, the leaf spring (limiting portion) 90, and the second movable iron core 8A. Since the direction of the force of the spring 9 is the same as the direction of the force that attracts the second movable iron core 8A when the solenoid S2 is energized, according to the above structure, even when the solenoid S2 is not energized, it can apply force to the object in the same direction as when it is energized.

[0151] Furthermore, according to the above configuration, as described above, when the solenoid S2 is energized, if the first movable iron core 7A moves toward the first fixed iron core 5 against the biasing force of the spring 9, the biasing force of the spring 9 is not transmitted to the second movable iron core 8A, and thus to the valve element (target object) 3. Therefore, the thrust of the solenoid S2 when energized and the biasing force applied to the target by the spring 9 when de-energized can be freely set. Furthermore, while the spring 9 is a coil spring in this embodiment, it may also be a spring other than a coil spring, such as a disc spring.

[0152] Furthermore, the solenoid S2 of this embodiment includes a connecting passage p5 that connects the first fixed iron core 5 side of the second movable iron core 8A with the second fixed iron core 6 side. This prevents liquid from being enclosed in spaces L8 and L9, for example, on the first fixed iron core 5 side of the second movable iron core 8A, and suppresses the generation of a damping force that would otherwise hinder the movement of the second movable iron core 8A. Consequently, the solenoid S2 of this embodiment prevents the generation of a damping force even when the second movable iron core 8A is moving at high speed, allowing the second movable iron core 8A to move smoothly.

[0153] The solenoid S2 of this embodiment also includes an annular filling ring 41, which is mounted between the first fixed core 5 and the second fixed core 6. Furthermore, the first movable core 7A includes an inner cylindrical portion 7e and an outer cylindrical portion 7f, arranged in two layers; a connecting portion 7g connecting one axial end of the inner and outer cylindrical portions 7e and 7f; and an inner bottom portion 7h at the other end of the inner cylindrical portion 7e, which is slidably inserted into the filling ring 41, with the inner bottom portion 7h facing the second fixed core 6. Meanwhile, the second movable core 8A is a bottomed cylindrical portion having an outer bottom portion 8d and an intermediate cylindrical portion 8e extending from the outer periphery of the outer bottom portion 8d and having an inner diameter greater than that of the inner cylindrical portion 7e of the first movable core 7A. The intermediate cylindrical portion 8e is slidably inserted into the outer cylindrical portion 7f of the first movable core 7A, with the outer bottom portion 8d facing the second fixed core 6. Furthermore, the spring 9 is attached between the inner bottom portion 7h and the first fixed core 5 so that one end side thereof is inserted into the inner side of the inner cylindrical portion 7e of the first movable core 7A.

[0154] According to the above structure, when the coil is excited, a magnetic circuit passes through the first fixed iron core 5, the first movable iron core 7A, the second movable iron core 8A, and the second fixed iron core 6, thereby attracting the first movable iron core 7A toward the first fixed iron core 5 and the second movable iron core 8A toward the second fixed iron core 6. Furthermore, space for accommodating the spring 9 can be ensured inside the first movable iron core 7A.

[0155] Further, according to the above-described configuration, when the first movable iron core 7A moves toward the second fixed iron core 6 side, the inner side bottom portion 7h of the first movable iron core 7A approaches the outer side bottom portion 8d of the second movable iron core 8A, and thus if the leaf spring (limiting portion) 90 is arranged so as to be able to limit the movement of these in the approaching direction, it is possible to limit the movement of the first movable iron core 7A toward the second fixed iron core 6 side with respect to the second movable iron core 8A. Also, in order to arrange the leaf spring 90 like this, it is sufficient to arrange the leaf spring 90 between the inner side bottom portion 7h of the first movable iron core 7A and the outer side bottom portion 8d of the second movable iron core 8A, for example, as in the present embodiment, and this is easy. That is, according to the above-described configuration, it is possible to easily arrange the leaf spring (limiting portion) 90.

[0156] Further, in the above-described solenoid S2, a gap 81 is formed between the inner cylindrical portion 7e of the first movable iron core 7A and the intermediate cylindrical portion 8e of the second movable iron core 8A. Due to this, the space L8 formed on the upper side (first fixed iron core 5 side) of the intermediate cylindrical portion 8e of the second movable iron core 8A and the space L9 formed on the upper side (first fixed iron core 5 side) of the outer side bottom portion 8d become one continuous space. Thus, if a communication passage p5 is formed so as to open this continuous space toward the second fixed iron core 6 side of the second movable iron core 8A, liquid will not be enclosed in this space. Thus, it is possible to reliably suppress the generation of a damping force that hinders the movement of the second movable iron core 8A, and to ensure smooth up-and-down movement of the second movable iron core 8A.

[0157] The preferred embodiments of the present application have been described in detail above, but modifications, alterations, and changes can be made thereto without departing from the scope of the claims.

[0158] This application claims priority based on Japanese Patent Application No. 2019-163878 filed on September 9, 2019 with the Japan Patent Office, the entire contents of which are incorporated herein by reference.

[0159] Explanation of Symbols

[0160] D Buffer

[0161] M Main Passage

[0162] L6, L8 Space

[0163] L7, L9 Space (between outer side bottom portion and inner side bottom portion)

[0164] O Throttle

[0165] p1 Pressure Introduction Passage

[0166] p2 Pressure Control Passage

[0167] p5 Communication Passage

[0168] p5a first communication passage

[0169] p5b second communication passage

[0170] S1, S2 solenoid

[0171] V electromagnetic valve

[0172] 1 cylinder

[0173] 2 main valve body

[0174] 3 valve core (valve body)

[0175] 4 coil

[0176] 5 first fixed iron core

[0177] 6 second fixed iron core

[0178] 7, 7A first movable iron core

[0179] 7a, 7h inner bottom

[0180] 7b, 7e inner cylindrical portion

[0181] 7c guide portion

[0182] 7d communication hole

[0183] 7f outer cylindrical portion

[0184] 7g connecting portion

[0185] 8, 8A second movable iron core

[0186] 8a, 8d outer bottom

[0187] 8b outer cylindrical portion

[0188] 8e intermediate cylindrical portion

[0189] 9 spring

[0190] 11 piston rod (rod)

[0191] 41 filling ring

[0192] 70, 80 gap

[0193] 90 flat spring (limiting portion)

Claims

1. A solenoid comprising: Coil; a first fixed iron core located at one end side of the coil in the axial direction; a second fixed iron core located at the other end side of the coil in the axial direction and having a gap with the first fixed iron core; a first movable iron core disposed between the first fixed iron core and the second fixed iron core and attracted by the first fixed iron core when power is supplied to the coil; a second movable iron core disposed between the first fixed iron core and the second fixed iron core and attracted by the second fixed iron core when power is supplied to the coil; a spring for urging the first movable iron core toward the second fixed iron core; a restriction portion that restricts movement of the first movable iron core toward the second fixed iron core relative to the second movable iron core; a connecting passage connecting the first fixed iron core side and the second fixed iron core side of the second movable iron core; and an annular filling ring installed between the first fixed iron core and the second fixed iron core, The second movable iron core is in the shape of a bottomed cylinder, having an outer bottom and an outer cylinder portion standing upright on the outer peripheral edge of the outer bottom. The outer bottom is axially movably inserted into the inner side of the filling ring with the outer bottom facing the second fixed iron core. The first movable iron core is in the shape of a bottomed cylinder, and has an inner bottom and an inner cylinder portion standing upright on the outer peripheral edge of the inner bottom. The inner bottom is directed toward the second fixed iron core, and the inner cylinder portion is inserted into the inner side of the outer cylinder portion so as to be movable in the axial direction. The spring is installed between the inner bottom portion and the first fixed core so that one end side thereof is inserted into the inner side of the inner cylindrical portion.

2. The solenoid according to claim 1, in, The communication passage is formed in the outer bottom portion, opens between the outer bottom portion and the inner bottom portion, and communicates with a space formed on the first fixed core side of the outer cylinder portion via a gap formed between the outer cylinder portion and the inner cylinder portion.

3. The solenoid according to claim 2, in, The first movable iron core has a guide portion, which is located at the outer periphery of the front end portion of the inner cylinder portion protruding outward from the outer cylinder portion and is in sliding contact with the inner periphery of the filling ring. The outer diameter of the inner cylindrical portion is smaller than the inner diameter of the outer cylindrical portion.

4. The solenoid according to claim 1, in, The connecting passage is formed at the outer bottom, opens between the outer bottom and the inner bottom, and is connected to the space on the first fixed iron core side formed in the outer cylinder via the connecting hole formed in the inner bottom and the gap formed between the front end of the inner cylinder and the first fixed iron core.

5. The solenoid according to claim 1, in, As the connecting channel, there are provided: a first connecting channel formed at the outer bottom and opening between the outer bottom and the inner bottom; and a second connecting channel formed between the second movable iron core and the filling ring and opening to the space formed on the first fixed iron core side of the outer cylinder.

6. A solenoid valve comprising the solenoid according to claim 1, wherein the solenoid valve is provided in the middle of a pressure control passage. It has a valve body for opening and closing the pressure control channel, The solenoid applies a force to the valve body in a direction of closing the pressure control passage, which is generated when the coil is energized and attracts the second movable iron core toward the second fixed iron core.

7. A solenoid comprising: Coil; a first fixed iron core located at one end side of the coil in the axial direction; a second fixed iron core located at the other end side of the coil in the axial direction and having a gap with the first fixed iron core; a first movable iron core disposed between the first fixed iron core and the second fixed iron core and attracted by the first fixed iron core when power is supplied to the coil; a second movable iron core disposed between the first fixed iron core and the second fixed iron core and attracted by the second fixed iron core when power is supplied to the coil; a spring for urging the first movable iron core toward the second fixed iron core; a restriction portion that restricts movement of the first movable iron core toward the second fixed iron core relative to the second movable iron core; a connecting passage connecting the first fixed iron core side and the second fixed iron core side of the second movable iron core; and an annular filling ring installed between the first fixed iron core and the second fixed iron core, The first movable iron core comprises: an inner cylinder portion and an outer cylinder portion arranged in two layers; a connecting portion connecting one axial end of the inner cylinder portion and the outer cylinder portion; and an inner bottom portion located at the other end of the inner cylinder portion, the inner bottom portion being slidably inserted into the inner side of the filling ring with the inner bottom portion facing the second fixed iron core side. The second movable iron core is in the shape of a bottomed cylinder, and has an outer bottom and an intermediate cylinder portion standing upright on the outer peripheral edge of the outer bottom and having an inner diameter larger than the outer diameter of the inner cylinder portion. The outer bottom is directed toward the second fixed iron core, and the intermediate cylinder portion is slidably inserted into the inner side of the outer cylinder portion. The spring is installed between the inner bottom portion and the first fixed core so that one end side thereof is inserted into the inner side of the inner cylindrical portion.

8. A buffer comprising the solenoid valve according to claim 6 and comprising: cylinder; a rod movably inserted into the cylinder in the axial direction; a main channel for allowing liquid to flow when the cylinder and the rod move relative to each other in the axial direction; a main valve body, which opens and closes the main channel; a pressure introduction passage provided with a throttle in the middle thereof, for reducing the pressure on the upstream side of the main valve body of the main passage and guiding it to the back side of the main valve body; and The pressure control passage is connected to the pressure introduction passage at a position downstream of the throttle and is provided with the solenoid valve.

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