solenoid

Abstract

To provide a solenoid which can improve waterproofness of a seal member.SOLUTION: A mold coil 34 constituting a solenoid 33 includes a coil 34A, a bobbin 34B, and a resin part 34C. On the inner peripheral side of the mold coil 34, a housing 36 is arranged. The housing 36 is covered with a cover 51. Between a fitting cylindrical part 51A of the cover 51 and the resin part 34C of the mold coil 34, an O ring 52 for sealing therebetween is provided. The O ring 52 is mounted in a seal groove 51D provided on the cover 51. Both axial ends 51D1 and 51D2 of the seal groove 51D are formed at positions facing a cylindrical part 34C1 of the resin part 34C.SELECTED DRAWING: Figure 4

Description

Technical Field

[0005] , , ,

[0001] The present disclosure relates to a solenoid used, for example, in a damping force adjustment mechanism of a damping force adjustable shock absorber.

Background Art

[0002] A vehicle such as a four-wheel automobile is provided with a shock absorber (damper) between the vehicle body (above the spring) side and each wheel (below the spring) side. As such a shock absorber for a vehicle, a damping force adjustable hydraulic shock absorber (damping force adjustable shock absorber) that variably adjusts the damping force according to driving conditions, vehicle behavior, etc. is known. The damping force adjustable hydraulic shock absorber constitutes a semi-active suspension of the vehicle.

[0003] The damping force adjustable hydraulic shock absorber variably adjusts the generated damping force, for example, by adjusting the opening pressure of a damping force adjustment valve with a damping force variable actuator (damping force adjustment mechanism). As the damping force variable actuator, for example, a solenoid is used. Here, Patent Document 1 describes a solenoid including a coil, a bobbin around which the coil is wound, a storage portion disposed on the inner peripheral side of the bobbin and having an open end side, a mover provided movably in the winding axis direction of the coil within the storage portion, a stator provided at a position facing the opening of the storage portion, and a cover covering the opposite side in the axial direction to the opening of the storage portion.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] The solenoid described in Patent Document 1 has a seal groove in its cover, and a seal member (O-ring) is fitted into this seal groove. In this case, the seal groove faces the boundary between the bobbin and the resin part (outer resin) that covers the bobbin. That is, one side of the seal groove in the axial direction (the periphery of the movable side wall of the pair of side walls that make up the seal groove) faces the bobbin. Therefore, the seal member fitted into the seal groove comes into contact with the boundary between the bobbin and the resin part, which may lead to a decrease in the durability of the seal member. Furthermore, if there is a step at the boundary between the bobbin and the resin part, it may lead to a decrease in the adhesion of the seal member and damage due to contact between the seal member and the step, which may reduce the waterproof performance. If sufficient waterproof performance cannot be ensured, it may lead to a short circuit due to water ingress, for example.

[0006] An object of one embodiment of the present invention is to provide a solenoid that can improve the waterproofness of a sealing member. [Means for solving the problem]

[0007] One embodiment of the present invention is a solenoid, the solenoid comprising: a coil wound in an annular shape and generating a magnetic force when energized; a bobbin around which the coil is wound; a housing portion disposed on the inner circumference of the bobbin, extending in the direction of the winding axis of the coil and having an opening at one end; a movable element provided in the housing portion so as to be movable in the direction of the winding axis of the coil; a stator provided at a position opposite to the opening of the housing portion; a resin portion covering the bobbin; a cover covering the housing portion; a seal groove provided in the cover and a seal member fitted into the seal groove, wherein the axial end of the seal groove is It has an inner end that forms a side wall located on the side closer to the coil, and an outer end that forms a side wall located on the side farther from the coil, and the inner end and the outer end are Both are formed in positions opposite to the aforementioned resin part. The joint between the bobbin and the resin part, which forms the boundary between the bobbin and the resin part, is located closer to the coil than the inner end. ru. [Effects of the Invention]

[0008] According to one embodiment of the present invention, the waterproofing of the sealing member can be improved. [Brief explanation of the drawing]

[0009] [Figure 1] This is a longitudinal cross-sectional view showing a damping force adjustable shock absorber incorporating a solenoid according to an embodiment. [Figure 2] This is an enlarged cross-sectional view showing the damping force adjustment mechanism in Figure 1. [Figure 3] This is an enlarged cross-sectional view showing the solenoid in Figure 2. [Figure 4] This is an enlarged view of section (IV) in Figure 3. [Figure 5] This is a plan view of the bobbin as seen from the cover side. [Modes for carrying out the invention]

[0010] The following explanation will use the solenoid according to the embodiment as an example, specifically in the damping force adjustment mechanism of a damping force adjustable shock absorber incorporated into a vehicle such as a four-wheeled automobile, with reference to the attached drawings.

[0011] First, a damping force adjustable hydraulic shock absorber 1 incorporating the solenoid 33 according to this embodiment will be described. In Figure 1, the damping force adjustable hydraulic shock absorber 1 (hereinafter referred to as shock absorber 1) is equipped with a damping force adjustment mechanism 17 driven by the solenoid 33. That is, the shock absorber 1 as a damping force adjustable shock absorber is composed of an outer cylinder 2 and an inner cylinder 4 as cylinders, a piston 5, a piston rod 8, and a damping force adjustment mechanism 17.

[0012] The shock absorber 1, which is a hydraulic shock absorber, has a bottomed cylindrical outer casing 2 that forms the outer shell. The lower end of the outer casing 2 is closed by a bottom cap 3 using welding or the like. The upper end of the outer casing 2 is a crimped portion 2A that is bent radially inward. A rod guide 9 and a seal 10 are provided between the crimped portion 2A and the inner casing 4. On the other hand, an opening 2B is formed on the lower side of the outer casing 2, concentric with the connection port 12C of the intermediate casing 12. A damping force adjustment mechanism 17 is mounted on the lower side of the outer casing 2, facing the opening 2B. The bottom cap 3 is provided with a mounting eye 3A, which is attached, for example, to the wheel side of a vehicle.

[0013] An inner cylinder 4 is provided inside the outer cylinder 2, coaxially with the outer cylinder 2. The lower end of the inner cylinder 4 is fitted and attached to the bottom valve 13. The upper end of the inner cylinder 4 is fitted and attached to the rod guide 9. An oil liquid is sealed inside the outer cylinder 2 and inner cylinder 4, which function as cylinders, as a working fluid. The working fluid is not limited to an oil liquid; for example, water mixed with additives may also be used.

[0014] An annular reservoir chamber A is formed between the inner cylinder 4 and the outer cylinder 2. Gas is sealed inside reservoir chamber A along with the oil. This gas may be air at atmospheric pressure, or a gas such as compressed nitrogen gas may be used. Reservoir chamber A compensates for the entry and exit of the piston rod 8. At a point along the length (axial direction) of the inner cylinder 4, an oil hole 4A is drilled radially, which constantly connects the rod-side oil chamber B to the annular oil chamber D.

[0015] The piston 5 is slidably mounted within the inner cylinder 4. The piston 5 is inserted into the inner cylinder 4, dividing the inside of the inner cylinder 4 into two chambers: a rod-side oil chamber B (rod-side chamber) and a bottom-side oil chamber C (bottom-side chamber). Multiple oil passages 5A and 5B are formed in the piston 5, spaced apart in the circumferential direction, enabling communication between the rod-side oil chamber B and the bottom-side oil chamber C.

[0016] Here, an extension-side disc valve 6 is provided on the lower end surface of the piston 5. The extension-side disc valve 6 opens when the pressure in the rod-side oil chamber B exceeds the relief setting pressure when the piston 5 slides upward during the extension stroke of the piston rod 8, and this pressure is relieved to the bottom-side oil chamber C via each oil passage 5A. The relief setting pressure is set to a pressure higher than the valve opening pressure when the damping force adjustment mechanism 17 is set to hard.

[0017] On the upper end surface of the piston 5, a shrinkage-side check valve 7 is provided which opens when the piston 5 slides downward and is displaced during the shrinking stroke of the piston rod 8 and closes otherwise. The check valve 7 allows the oil in the bottom-side oil chamber C to flow through each oil passage 5B toward the rod-side oil chamber B and blocks the oil from flowing in the opposite direction. The opening pressure of the check valve 7 is set to a pressure lower than the opening pressure when the damping force adjustment mechanism 17 is set soft, and substantially no damping force is generated. This substantially no generation of damping force means a force below the friction of the piston 5 and the seal 10 and has no influence on the movement of the vehicle.

[0018] The piston rod 8 extends axially (the vertical direction in FIG. 1) inside the inner cylinder 4. The lower end side of the piston rod 8 is inserted inside the inner cylinder 4. The piston rod 8 is fixedly provided to the piston 5 by a nut 8A or the like. The upper end side of the piston rod 8 protrudes outside the outer cylinder 2 and the inner cylinder 4 via a rod guide 9. That is, the piston rod 8 has one side (one end), the lower side (lower end), connected to the piston 5 and the other side (the other end), the upper side (upper end), extending outside the inner cylinder 4 and the outer cylinder 2. Note that the lower end of the piston rod 8 may be further extended to protrude outward from the bottom portion (for example, the bottom cap 3) side, so-called double rods.

[0019] On the upper end side of the inner cylinder 4, a stepped cylindrical rod guide 9 is provided. The rod guide 9 positions the upper portion of the inner cylinder 4 at the center of the outer cylinder 2 and guides the piston rod 8 slidably in the axial direction on its inner peripheral side. An annular seal 10 is provided between the caulked portion 2A of the rod guide 9 and the outer cylinder 2. The seal 10 is formed, for example, by baking an elastic material such as rubber onto a metal circular ring plate provided with a hole through which the piston rod 8 is inserted at the center. The seal 10 seals between itself and the piston rod 8 when the inner periphery of the elastic material slidably contacts the outer peripheral side of the piston rod 8.

[0020] The seal 10 is formed with a lip seal 10A as a check valve that extends to contact the rod guide 9 on the lower surface side. The lip seal 10A is disposed between the oil sump chamber 11 and the reservoir chamber A. The lip seal 10A allows the oil fluid etc. in the oil sump chamber 11 to flow toward the reservoir chamber A side through the return passage 9A of the rod guide 9, and blocks the reverse flow.

[0021] An intermediate cylinder 12 made of a cylinder body is disposed between the outer cylinder 2 and the inner cylinder 4. The intermediate cylinder 12 is attached, for example, to the outer peripheral side of the inner cylinder 4 via upper and lower cylindrical seals 12A and 12B. The intermediate cylinder 12 forms an annular oil chamber D inside that extends so as to surround the outer peripheral side of the inner cylinder 4 over the entire circumference. The annular oil chamber D is an oil chamber independent of the reservoir chamber A. The annular oil chamber D is constantly in communication with the rod side oil chamber B through a radial oil hole 4A formed in the inner cylinder 4. The annular oil chamber D constitutes a part of a flow path in which a flow of the working liquid is generated by the movement of the piston rod 8. A connection port 12C to which a connection pipe body 20 of the damping force adjustment valve 18 is attached is provided on the lower end side of the intermediate cylinder 12.

[0022] The bottom valve 13 is located on the lower end side of the inner cylinder 4 and is provided between the bottom cap 3 and the inner cylinder 4. The bottom valve 13 includes a valve body 14 that partitions (divides) the reservoir chamber A and the bottom side oil chamber C between the bottom cap 3 and the inner cylinder 4, a reduced side disk valve 15 provided on the lower surface side of the valve body 14, and an extended side check valve 16 provided on the upper surface side of the valve body 14. Oil passages 14A and 14B that enable the reservoir chamber A and the bottom side oil chamber C to communicate with each other are formed in the valve body 14 at intervals in the circumferential direction.

[0023] The reduced side disk valve 15 opens when the pressure in the bottom side oil chamber C exceeds the relief set pressure when the piston 5 slides downward during the reduction stroke of the piston rod 8, and relieves the pressure at this time to the reservoir chamber A side through each oil passage 14A. The relief set pressure is set to a pressure higher than the valve opening pressure when the damping force adjustment mechanism 17 is set hard.

[0024] The extension-side check valve 16 opens when the piston 5 slides upward during the extension stroke of the piston rod 8, and closes at all other times. The check valve 16 allows the oil in the reservoir chamber A to flow through each oil passage 14B toward the bottom-side oil chamber C, and prevents the oil from flowing in the opposite direction. The opening pressure of the check valve 16 is set to a pressure lower than the opening pressure when the damping force adjustment mechanism 17 is set to soft, and thus does not generate any damping force.

[0025] Next, the damping force adjustment mechanism 17 for variably adjusting the damping force generated by the shock absorber 1 will be explained, referring to both Figure 1 and Figure 2.

[0026] The damping force adjustment mechanism 17 generates damping force by controlling the flow of the working fluid (oil) produced by the sliding of the piston 5 inside the cylinder (inner cylinder 4), and also variably adjusts the damping force generated by the shock absorber 1. In Figure 2, the damping force adjustment mechanism 17 shows the state in which the armature 48, operating pin 49, and pilot valve body 32 have moved to the left side of Figure 2 by applying external current to the coil 34A of the solenoid 33 (for example, control to generate a hard damping force). In other words, the damping force adjustment mechanism 17 in Figure 2 shows the closed valve state in which the pilot valve body 32 is seated on the valve seat portion 26E of the pilot body 26.

[0027] As shown in Figure 1, the damping force adjustment mechanism 17 is positioned with its base end (left end in Figure 1) interposed between the reservoir chamber A and the annular oil chamber D, and its tip end (right end in Figure 1) is provided to protrude radially outward from the lower side of the outer cylinder 2. The damping force adjustment mechanism 17 generates damping force by controlling the flow of oil from the annular oil chamber D to the reservoir chamber A using a damping force adjustment valve 18 (main valve 23, pilot valve body 32). Furthermore, the generated damping force is variably adjusted by adjusting the opening pressure of the damping force adjustment valve 18 (main valve 23, pilot valve body 32) with a solenoid 33 used as a variable damping force actuator.

[0028] Thus, the damping force adjustment mechanism 17 generates damping force by controlling the flow of working fluid (oil) generated by the sliding of the piston 5 inside the inner cylinder 4. For this purpose, the damping force adjustment mechanism 17 is composed of a damping force adjustment valve 18 and a solenoid 33. The damping force adjustment valve 18 generates damping force with hard or soft characteristics by variably controlling the flow of oil from the annular oil chamber D to the reservoir chamber A. The damping force adjustment valve 18 is driven by the solenoid 33.

[0029] In other words, the damping force adjustment valve 18 is a valve whose opening and closing operation is adjusted by a solenoid 33, and is located in a passage (for example, between the annular oil chamber D and the reservoir chamber A) where the flow of working fluid is generated by the movement (extension and contraction) of the piston rod 8. The solenoid 33 adjusts the opening and closing operation of the damping force adjustment valve 18 (pilot valve body 32, and consequently the main valve 23). In this case, the opening pressure of the damping force adjustment valve 18 (pilot valve body 32, and consequently the main valve 23) is adjusted by the solenoid 33, which is used as a variable damping force actuator, thereby variably controlling the generated damping force to have hard or soft characteristics.

[0030] Here, as shown in Figures 1 and 2, the damping force adjustment valve 18 is composed of a valve case 19, a connecting pipe 20, and a valve member 21. The valve case 19 is formed in a substantially cylindrical shape, with its base end fixed around the opening 2B of the outer cylinder 2, and its tip end protruding radially outward from the outer cylinder 2. The connecting pipe 20 has its base end fixed to the connection port 12C of the intermediate cylinder 12, and its tip end is an annular flange portion 20A, which is disposed inside the valve case 19 with a gap. The valve member 21 is in contact with the flange portion 20A of the connecting pipe 20.

[0031] As shown in Figure 2, the base end of the valve case 19 has an annular inner flange portion 19A that extends radially inward. The tip end of the valve case 19 has a male threaded portion 19B to which a lock nut 53 is screwed, connecting the valve case 19 to the yoke 39 (one side cylindrical portion 39G) of the solenoid 33. The space between the inner circumferential surface of the valve case 19 and the outer circumferential surface of the valve member 21, and further, the space between the inner circumferential surface of the valve case 19 and the outer circumferential surface of the pilot body 26, etc., is an annular oil chamber 19C that is in constant communication with the reservoir chamber A. Note that in addition to connecting the valve case 19 and the solenoid 33 with the lock nut 53, the valve case 19 and the solenoid 33 may also be connected in a configuration where, for example, the tip end of the valve case is crimped to the yoke of the solenoid (a configuration without using a lock nut).

[0032] The inside of the connecting pipe 20 has an oil passage 20B on one side that communicates with the annular oil chamber D and on the other side that extends to the position of the valve member 21. An annular spacer 22 is provided sandwiched between the flange portion 20A of the connecting pipe 20 and the inner flange portion 19A of the valve case 19. Multiple notches 22A are provided radially on the spacer 22, which serve as radial oil passages to connect the oil chamber 19C and the reservoir chamber A. In this embodiment, the notches 22A for forming oil passages are provided on the spacer 22. However, instead of the spacer 22, notches (grooves) for forming oil passages may be provided radially on the inner flange portion 19A of the valve case 19.

[0033] The valve member 21 is provided with a central hole 21A located at the radial center and extending axially. The valve member 21 also has multiple oil passages 21B spaced circumferentially around the central hole 21A. One side of each oil passage 21B (the left side in Figures 1 and 2) is constantly in communication with the oil passage 20B side of the connecting pipe 20. The other end face of the valve member 21 (the right side in Figures 1 and 2) is provided with an annular recess 21C formed to surround the other side opening of the oil passage 21B, and an annular valve seat 21D located radially outside the annular recess 21C, on which the main valve 23 sits and unseats. Each oil passage 21B of the valve member 21 serves as a flow path for pressurized oil, with a flow rate corresponding to the opening of the main valve 23, between the oil passage 20B of the connecting pipe 20, which communicates with the annular oil chamber D, and the oil chamber 19C of the valve case 19, which communicates with the reservoir chamber A.

[0034] The main valve 23 is composed of a disc valve. The inner circumference of the main valve 23 is sandwiched between the valve member 21 and the large diameter portion 24A of the pilot pin 24. The outer circumference of the main valve 23 seats away from the annular valve seat 21D of the valve member 21. An elastic seal 23A is fixed to the outer circumference on the back side of the main valve 23 by means of seizing or other means. The main valve 23 opens by receiving pressure from the oil passage 21B side (annular oil chamber D side) of the valve member 21 and separating from the annular valve seat 21D. As a result, the oil passage 21B (annular oil chamber D side) of the valve member 21 is connected to the oil chamber 19C (reservoir chamber A side) via the main valve 23, and the amount (flow rate) of pressurized oil flowing in the direction of arrow Y is variably adjusted according to the opening degree of the main valve 23.

[0035] The pilot pin 24 is formed in a stepped cylindrical shape, with an annular large-diameter portion 24A provided in the axial middle. The pilot pin 24 has a central hole 24B that extends axially on its inner circumference. A small-diameter hole (orifice 24C) is formed at one end of the central hole 24B (the end on the connecting pipe body 20 side). One end of the pilot pin 24 (the left end in Figures 1 and 2) is press-fitted into the central hole 21A of the valve member 21. In this state, the large-diameter portion 24A of the pilot pin 24 sandwiches the main valve 23 between itself and the valve member 21.

[0036] The other end of the pilot pin 24 (the right end in Figures 1 and 2) is fitted into the central hole 26C of the pilot body 26. An axially extending oil passage 25 is formed between the central hole 26C of the pilot body 26 and the other end of the pilot pin 24. This oil passage 25 communicates with the back pressure chamber 27 formed between the main valve 23 and the pilot body 26. In other words, multiple axially extending oil passages 25 are provided circumferentially on the side surface of the other end of the pilot pin 24, and the other circumferential positions are press-fitted into the central hole 26C of the pilot body 26.

[0037] The pilot body 26 is formed as a substantially bottomed cylindrical body and has a cylindrical portion 26A with a stepped hole formed on the inside and a bottom portion 26B that closes the cylindrical portion 26A. The bottom portion 26B of the pilot body 26 is provided with a central hole 26C into which the other end of the pilot pin 24 is fitted. A protruding cylindrical portion 26D is integrally provided on one end of the bottom portion 26B of the pilot body 26 (the left end in Figures 1 and 2), located on the outer diameter side and protruding towards the valve member 21 along its entire circumference. The elastic seal 23A of the main valve 23 is liquid-tightly fitted to the inner circumferential surface of the protruding cylindrical portion 26D, thereby forming a back pressure chamber 27 between the main valve 23 and the pilot body 26. The back pressure chamber 27 generates pressure (internal pressure, pilot pressure) that presses the main valve 23 in the closing direction, that is, in the direction that causes the main valve 23 to seat on the annular valve seat 21D of the valve member 21.

[0038] At the other end of the bottom portion 26B of the pilot body 26 (the right end in Figures 1 and 2), a valve seat portion 26E is provided so as to surround the central hole 26C, on which the pilot valve body 32 sits and unseats. Inside the cylindrical portion 26A of the pilot body 26, a return spring 28 is provided to bias the pilot valve body 32 away from the valve seat portion 26E of the pilot body 26. A disc valve 29 constitutes a fail-safe valve when the solenoid 33 is not energized (when the pilot valve body 32 is furthest away from the valve seat portion 26E). A retaining plate 30 with an oil passage 30A formed on its central side is also provided.

[0039] At the open end of the cylindrical portion 26A of the pilot body 26, a cap 31 is fitted and fixed with a return spring 28, a disc valve 29, a retaining plate 30, etc., arranged inside the cylindrical portion 26A. The cap 31 has, for example, four notches 31A formed at spaced apart in the circumferential direction. As shown by arrow X in Figure 2, the notches 31A serve as passages that allow the oil liquid that has flowed to the solenoid 33 side through the oil passage 30A of the retaining plate 30 to flow to the oil chamber 19C (reservoir chamber A side).

[0040] The pilot valve body 32, together with the pilot body 26, constitutes a pilot valve (control valve). The pilot valve body 32 is formed in a stepped cylindrical shape. The tip of the pilot valve body 32, that is, the tip that seats away from the valve seat portion 26E of the pilot body 26, is tapered. The operating pin 49 of the solenoid 33 is fitted and fixed inside the pilot valve body 32, and the opening pressure of the pilot valve body 32 is adjusted in accordance with the energization supplied to the solenoid 33.

[0041] In other words, the pilot valve (pilot body 26 and pilot valve element 32), which acts as a control valve, is controlled by the axial movement of the operating pin 49 of the solenoid 33 (more specifically, the armature 48 fixed to the operating pin 49). A flange portion 32A, which acts as a spring seat, is formed around the entire circumference of the base end of the pilot valve element 32. The flange portion 32A constitutes a fail-safe valve by contacting the inner circumference of the disc valve 29 when the solenoid 33 is de-energized, that is, when the pilot valve element 32 is displaced to the fully open position, which is furthest from the valve seat portion 26E.

[0042] Next, the solenoid 33, which constitutes the damping force adjustment mechanism 17 together with the damping force adjustment valve 18, will be explained with reference to Figures 1 and 2, as well as Figure 3. Note that in Figure 3, the right side in the left-right direction of Figure 2 is considered the upper side, and the reference numerals are assigned accordingly. That is, the left-right direction in Figures 1 and 2 corresponds to the up-down direction in Figures 3 and 4.

[0043] The solenoid 33 is incorporated into the damping force adjustment mechanism 17 as a variable damping force actuator. That is, the solenoid 33 is used in a damping force adjustable shock absorber to adjust the on-off valve operation of the damping force adjustment valve 18. The solenoid 33 comprises a molded coil 34, a housing 36 which serves as a storage part (magnetic member), a yoke 39 which serves as a case part, an anchor 41 which serves as a stator (fixed iron core), a cylinder 44 which serves as a joint part (non-magnetic ring), an armature 48 which serves as a movable part (movable iron core), an operating pin 49 which serves as a shaft part, and a cover 51 which serves as a cover part.

[0044] The molded coil 34 is formed in a substantially cylindrical shape by winding a coil 34A around a bobbin 34B (coil bobbin) and then integrally covering (molding) these with a resin part 34C made of thermoplastic resin or thermosetting resin. The resin part 34C is a resin component and corresponds to the outer resin of the coil 34A. A cable outlet 34E is provided on a part of the circumferential direction of the molded coil 34, protruding outward in the axial or radial direction. An electric wire cable (not shown) is connected to the cable outlet 34E. The coil 34A of the molded coil 34 is wound in a ring around the bobbin 34B, and when power is supplied (energized) from an external cable, it becomes an electromagnet and generates a magnetic field (magnetic force).

[0045] A seal groove 34D is formed around the entire circumference of the resin portion 34C of the molded coil 34 on the side (the end face on one axial side) facing the yoke 39 (annular portion 39B). An O-ring 35 is fitted inside the seal groove 34D. The O-ring 35 provides a liquid-tight seal between the molded coil 34 and the yoke 39 (annular portion 39B). This prevents rainwater and dust containing mud from entering the cylindrical projection 39C side of the yoke 39 through the gap between the yoke 39 and the molded coil 34.

[0046] In this embodiment, the coil member used is a molded coil 34 consisting of a coil 34A, a bobbin 34B, and a resin part 34C. Specifically, the coil member, which is integrally formed including the coil 34A, is constructed by winding the coil 34A around a bobbin 34B made of an electrically insulating material, and then molding (overmolding) a resin material over it (outer circumference side), thereby covering the outer circumference of the coil 34A with the resin part 34C.

[0047] The housing 36 constitutes a first fixed core (storage section) positioned on the inner circumference side of the molded coil 34 (i.e., the inner circumference of the coil 34A). The housing 36 is formed as a covered cylindrical body from a magnetic material (magnetic body) such as low carbon steel or carbon steel for machine structures (S10C). The housing 36 is composed of a storage cylinder section 36A, a lid section 36B, and a small-diameter cylinder section 36C. The storage cylinder section 36A extends in the direction of the winding axis of the molded coil 34 (coil 34A), and is open at one end (left side in Figure 2, lower side in Figure 3). The lid section 36B closes the other end of the storage cylinder section 36A (right side in Figure 2, upper side in Figure 3). The small-diameter cylinder section 36C is located on the opening side (one side) of the storage cylinder section 36A and is formed to reduce the outer diameter of the storage cylinder section 36A.

[0048] The inner circumference of the cylinder 44 is joined to the outer circumference of the small-diameter cylindrical portion 36C of the housing 36 by brazing. The inner diameter of the housing cylindrical portion 36A of the housing 36 is formed to be slightly larger than the outer diameter of the armature 48. The armature 48 is housed within the housing cylindrical portion 36A so as to be movable in the axial direction. That is, the housing 36 has an opening at one end in the axial direction, and the armature 48 is housed therein. The housing 36 and the cylinder 44 form a pressure vessel by press-fitting the housing 36 (small-diameter cylindrical portion 36C) into the inside of the cylinder 44 and brazing them together.

[0049] On the other hand, the lid portion 36B of the housing 36 is formed integrally with the storage cylinder portion 36A as a covered cylindrical body that closes the storage cylinder portion 36A from the other axial side. The outer diameter of the lid portion 36B is smaller than the outer diameter of the storage cylinder portion 36A and has a stepped shape. The fitting cylinder portion 51A of the cover 51 is fitted to the outer circumference of the lid portion 36B. In addition, the housing 36 has a bottomed stepped hole 37 located inside the lid portion 36B. The stepped hole 37 has a bush mounting hole portion 37A and a small-diameter hole portion 37B which is located further back than the bush mounting hole portion 37A and has a smaller diameter. A first bush 38 is provided inside the bush mounting hole portion 37A as a bearing (first bearing) for slidably supporting the operating pin 49.

[0050] Furthermore, the lid portion 36B of the housing 36 is positioned opposite the lid plate 51B of the cover 51 with an axial gap between them. This axial gap prevents axial force from being directly applied to the housing 36 from the lid plate 51B side of the cover 51 via the lid portion 36B. It should be noted that the lid portion 36B of the housing 36 does not necessarily have to be formed integrally with the storage cylinder portion 36A from the same material (magnetic material). In this case, the lid portion 36B can be formed from a material other than a magnetic material, such as a rigid metal material, ceramic material, or fiber-reinforced resin material. The joint between the storage cylinder portion 36A and the lid portion 36B of the housing 36 is positioned to allow for the transfer of magnetic flux.

[0051] The yoke 39 is provided on one side in the direction of movement of the armature 48. The yoke 39 is a magnetic member that, together with the housing 36, forms a magnetic circuit (magnetic path) across the inner and outer circumferences of the molded coil 34 (coil 34A). That is, the yoke 39 is formed using a magnetic material (magnetic body) similar to the housing 36. The yoke 39 is composed of an annular portion 39B that extends radially on one axial side (one side in the winding axis direction) of the molded coil 34 (coil 34A), with its inner circumference being a stepped fixing hole 39A, and a cylindrical projection 39C that protrudes cylindrically from the inner circumference of the annular portion 39B toward the other axial side (coil 34A side) along the axial direction of the fixing hole 39A. The cylindrical projection 39C constitutes a projection (cylindrical portion) for joining with the cylinder 44, and the cylinder 44 is inserted into the inner diameter side of the cylindrical projection 39C.

[0052] In other words, the yoke 39 has a fixing hole 39A, and the anchor 41 is positioned within the fixing hole 39A. Furthermore, an inward-facing flange portion 39D is provided within the fixing hole 39A, projecting inward along its entire circumference. The side surface of the inward-facing flange portion 39D (the side surface on the coil 34A side) is in contact with the axial end face (one end face) of the cylinder 44. In addition, the outer circumference of the axial side of the cylinder 44 is fitted into the inner circumference of the yoke 39, that is, the inner surface of the fixing hole 39A (in other words, the inner circumferential surface of the cylindrical projection portion 39C).

[0053] Furthermore, the yoke 39 is formed as a single unit including a cylindrical one-side section 39G extending from the outer circumference of the annular section 39B toward one axial side (towards the main valve 23), an other-side section 39H extending from the outer circumference of the annular section 39B toward the other axial side (towards the cover 51) and formed to surround the molded coil 34 from the radially outer side, and a crimping section 39J provided at the tip of the other-side section 39H to hold the flange 51C of the cover 51 in a non-detachable state. The other-side section 39H of the yoke 39 is provided with a notch 39K to expose the cable outlet section 34E of the molded coil 34 to the outside of the other-side section 39H.

[0054] Between the one cylindrical portion 39G and the other cylindrical portion 39H of the yoke 39, there are engagement recesses 39L with a semicircular cross-section that open to the outer circumferential surface of the yoke 39 (either all around or at multiple locations spaced apart in the circumferential direction). A lock nut 53, which is screwed onto the valve case 19, engages with the engagement recesses 39L via a retaining ring 54 (Figure 2). Furthermore, a seal groove 39M is provided all around the outer circumferential surface of the one cylindrical portion 39G. An O-ring 40 (Figure 2) is fitted into the seal groove 39M. The O-ring 40 provides a liquid-tight seal between the yoke 39 (one cylindrical portion 39G) and the valve case 19 of the damping force adjustment valve 18.

[0055] The anchor 41 is provided on one side of the armature 48 in the direction of movement. The anchor 41 is positioned opposite the armature 48 in the axial direction. The anchor 41 is a stator (second fixed core) fixed in the fixing hole 39A of the yoke 39 by means of press-fitting or other means. The anchor 41, like the housing 36 (first fixed core) and the yoke 39, is formed from a magnetic material (magnetic body) such as low carbon steel or machine structural carbon steel (S10C) to fill the fixing hole 39A of the yoke 39 from the inside. The anchor 41 is formed as a short cylindrical annular body with a through hole 41A extending in the axial direction at its center. One axial side of the anchor 41 (the side facing the cap 31 in the axial direction as shown in Figure 2) is formed to be a flat surface, similar to one side of the annular portion 39B of the yoke 39.

[0056] On the other axial side of the anchor 41 (the side opposite the armature 48 in the axial direction), a circular recess 41B is provided, coaxial with the housing cylinder 36A of the housing 36. The recess 41B is formed as a circular groove slightly larger in diameter than the armature 48, so that the armature 48 can be inserted into and out of it by magnetic force. For this purpose, a cylindrical outer circumferential protrusion 41C is provided on the other side of the anchor 41. The outer circumferential surface on the opening side of the outer circumferential protrusion 41C is formed as a conical surface so that the magnetic properties between the anchor 41 and the armature 48 are linear. That is, the outer circumferential protrusion 41C, also called a corner, protrudes cylindrically from the outer circumference of the anchor 41 toward the other axial side. The outer circumferential surface of the outer circumferential protrusion 41C (the outer circumferential surface on the opening side) is a conical surface that is tapered so that the outer diameter gradually decreases toward the other axial side (opening side).

[0057] Furthermore, a side portion 41D is formed on the outer circumference of the anchor 41, extending away from the opening of the housing cylinder portion 36A of the housing 36 along the outer circumference of the outer peripheral protrusion 41C. The end of this side portion 41D that is away from the opening is an annular flange portion 41E that protrudes radially outward. The annular flange portion 41E is positioned at a location significantly separated in one axial direction from the opening end of the housing cylinder portion 36A of the housing 36 (i.e., the end opposite to the recessed portion 41B).

[0058] The annular flange portion 41E is fixed, for example, by means of press-fitting into the fixing hole 39A of the yoke 39. The annular flange portion 41E serves as the fixing portion of the anchor 41 (side portion 41D) to the fixing hole 39A of the yoke 39, and is also the portion where the flange portion 41E and the fixing hole 39A face each other in the radial direction. The side portion 41D of the anchor 41 (excluding the annular flange portion 41E) faces the inner circumferential surface of the cylinder 44 and the inner surface of the inward-facing flange portion 39D of the yoke 39 with a gap (radial gap) between them.

[0059] As shown in Figure 3, a second bush 43, which serves as a bearing (second bearing) for slidably supporting the operating pin 49, is fitted into a stepped through hole 41A formed on the central (inner circumference) side of the anchor 41. On the other hand, as shown in Figure 2, a pilot body 26, a return spring 28, a disc valve 29, a retaining plate 30, and a cap 31 are inserted and provided on the inner circumference side of one side cylindrical portion 39G of the yoke 39. In addition, the valve case 19 of the damping force adjustment valve 18 is fitted (externally fitted) to the outer circumference side of one side cylindrical portion 39G.

[0060] The cylinder 44 is located between the yoke 39 and the anchor 41 in the radial direction. Furthermore, the cylinder 44 is located between the yoke 39 and the housing 36 in both the axial and radial directions. That is, the cylinder 44 is a non-magnetic connecting member (joint) located between the small-diameter cylindrical portion 36C of the housing 36 and the cylindrical projection 39C of the yoke 39, and provided on the inner circumference side of the molded coil 34 (coil 34A). The cylinder 44 is made of a non-magnetic material. More specifically, the cylinder 44 is formed as a cylindrical body (simple cylindrical body) from a non-magnetic material such as austenitic stainless steel.

[0061] The cylinder 44 is joined to the inner circumference of the yoke 39 (fixing hole 39A, cylindrical projection 39C) at one end (yoke 39 side) in the winding axis direction of the molded coil 34 (coil 34A). In this way, the cylinder 44 is fixed to the yoke 39, which has one side in the axial direction as a stator. The other end (housing 36 side) of the cylinder 44 in the winding axis direction is joined to the outer circumference of the housing 36 (small diameter cylindrical portion 36C). That is, the cylinder 44 is fitted (press-fitted) to the outside (outer circumference side) of the small diameter cylindrical portion 36C of the housing 36, and the two are joined by brazing.

[0062] The armature 48, also called a plunger, is positioned between the housing cylinder 36A of the housing 36 and the recess 41B of the anchor 41. The armature 48 is a movable element (movable core) made of a magnetic material that is movable in the direction of the winding axis of the coil 34A. That is, the armature 48 is provided on the inner circumference side of the coil 34A so as to be movable in the axial direction. The armature 48 is positioned on the inner circumference side of the housing cylinder 36A of the housing 36, the recess 41B of the anchor 41, the cylindrical projection 39C of the yoke 39, and the cylinder 44, and is movable in the axial direction between the housing cylinder 36A of the housing 36 and the recess 41B of the anchor 41. That is, the armature 48 is positioned on the inner circumference side of the housing cylinder 36A of the housing 36 and the recess 41B of the anchor 41, and is movable in the axial direction via the first and second bushings 38, 43 and the operating pin 49 due to the magnetic force generated in the coil 34A.

[0063] The armature 48 is fixed (integrated) to an actuation pin 49 that extends through its center and moves together with the actuation pin 49. The actuation pin 49 is axially slidable between the lid 36B of the housing 36 and the anchor 41 via first and second bushings 38 and 43. Here, the armature 48 is formed in a substantially cylindrical shape using an iron-based magnetic material, similar to the housing 36, yoke 39, and anchor 41. The magnetic force generated in the coil 34A generates a thrust (attractive force) in the direction that attracts the armature 48 toward the recess 41B of the anchor 41.

[0064] The actuation pin 49 is the shaft portion that transmits the thrust of the armature 48 to the pilot valve body 32, and is formed of a hollow rod. The actuation pin 49 is displaced integrally with the armature 48. That is, the armature 48 is integrally fixed to the axial middle portion of the actuation pin 49 by means of press-fitting or other means, thereby sub-assemblying the armature 48 and the actuation pin 49. Both axial sides of the actuation pin 49 are slidably supported by the cover portion 36B on the housing 36 side and the yoke 39 (anchor 41) via first and second bushings 38 and 43.

[0065] One end of the actuation pin 49 (the left end in Figure 2, the lower end in Figure 3) protrudes axially from the anchor 41 (yoke 39), and the pilot valve body 32 of the damping force adjustment valve 18 is fixed to this protruding end. Therefore, the pilot valve body 32 moves integrally in the axial direction together with the armature 48 and the actuation pin 49. In other words, the opening pressure of the pilot valve body 32 is a pressure value corresponding to the thrust of the armature 48 based on the energization of the coil 34A. The armature 48 moves axially due to the magnetic force from the coil 34A, thereby opening and closing the pilot valve of the buffer 1 (i.e., the pilot valve body 32 relative to the pilot body 26).

[0066] The cover 51 is a magnetic cover that covers the molded coil 34 from the outside, together with the other cylindrical portion 39H of the yoke 39. This cover 51 is made of a magnetic material (magnetic body) and serves as a lid that covers the molded coil 34 from the other axial side. The cover 51 is a metal member and, together with the other cylindrical portion 39H of the yoke 39, forms a magnetic circuit (magnetic path) on the outside of the molded coil 34 (coil 34A). The cover 51 is formed as a lidded cylindrical shape and is generally composed of a cylindrical fitting cylinder portion 51A and a disc-shaped lid plate 51B that closes the other end of the fitting cylinder portion 51A (the right end in Figure 2, the upper end in Figure 3).

[0067] Here, the fitting cylinder portion 51A of the cover 51 is inserted onto the outer circumference of the lid portion 36B of the housing 36, and in this state, the lid portion 36B of the housing 36 is housed inside. On the other hand, the lid plate 51B of the cover 51 has an annular flange portion 51C that extends radially outward from the fitting cylinder portion 51A on its outer circumference, and the outer diameter side of the flange portion 51C is fixed to a crimping portion 39J provided on the other side cylinder portion 39H of the yoke 39. As a result, the other side cylinder portion 39H of the yoke 39 and the lid plate 51B of the cover 51 are pre-assembled (sub-assembled) with the molded coil 34 built inside, as shown in Figure 3.

[0068] In this configuration, with the molded coil 34 housed inside the other cylindrical portion 39H of the yoke 39 and the lid plate 51B of the cover 51, the lid portion 36B of the housing 36 is fitted into the fitting cylindrical portion 51A of the cover 51. This allows for the transfer of magnetic flux between the fitting cylindrical portion 51A of the cover 51, the lid plate 51B, and the yoke 39. Furthermore, a seal groove 51D is formed around the entire circumference of the fitting cylindrical portion 51A of the cover 51, where the resin portion 34C of the molded coil 34 is fitted. An O-ring 52 is installed in this seal groove 51D as a sealing member. The O-ring 52 provides a liquid-tight seal between the molded coil 34 and the cover 51 (fitting cylindrical portion 51A). This prevents rainwater and dust containing mud from entering the space between the cover 51 and the molded coil 34, the space between the housing 36 and the molded coil 34, and even the space between the housing 36 and the cover 51.

[0069] As shown in Figure 3, the yoke 39 and cover 51 have a molded coil 34 built inside, and as shown in Figure 2, they are fastened to the valve case 19 of the damping force adjustment valve 18 using a lock nut 53 and a retaining ring 54 as fastening members. In this case, the retaining ring 54 is attached to the engagement recess 39L of the yoke 39 before the lock nut 53. This retaining ring 54 partially protrudes radially outward from the engagement recess 39L of the yoke 39 and transmits the fastening force from the lock nut 53 to the cylindrical portion 39G on one side of the yoke 39.

[0070] The lock nut 53 is formed as a stepped cylindrical body and has a female threaded portion 53A located on one axial side and on its inner circumference that screws into the male threaded portion 19B of the valve case 19, and an engaging cylindrical portion 53B that is bent radially inward so that its inner diameter is smaller than the outer diameter of the retaining ring 54 and engages with the retaining ring 54 from the outside. The lock nut 53 is a fastening member that integrally connects the damping force adjustment valve 18 and the solenoid 33 by screwing the female threaded portion 53A and the male threaded portion 19B of the valve case 19 together with the inner surface of the engaging cylindrical portion 53B in contact with the retaining ring 54 which is mounted in the engaging recess 39L of the yoke 39.

[0071] Now, let's consider the waterproofing of the O-ring 52 provided between the molded coil 34 of the solenoid 33 and the cover 51. The O-ring 52, which serves as a sealing member, is fitted into a seal groove 51D provided in the cover 51. Here, for example, let's consider the case where the seal groove of the cover faces the boundary between the bobbin and the resin part (exterior resin) that constitute the molded coil. That is, let's consider the case where the periphery of the side wall on the movable element (armature) side of the pair of side walls (side walls that face each other in the axial direction) that constitute the seal groove faces the bobbin. In this case, the O-ring fitted into the seal groove will come into contact with the boundary between the bobbin and the resin part, which may lead to a decrease in the durability of the O-ring. In particular, if there is a step at the boundary between the bobbin and the resin part, it may lead to a decrease in the airtightness of the O-ring and damage due to contact between the O-ring and the step, which may reduce the waterproofing. If sufficient waterproofing cannot be ensured, it may lead to a short circuit due to water ingress, for example. Furthermore, if the solenoid's shaft length (axial dimension) is shortened while waterproofing the gap between the cover and the resin part with an O-ring, the wall thickness of the bobbin and the resin part will become uneven. In this case, shrinkage (distortion) may occur, potentially worsening moldability.

[0072] Therefore, in this embodiment, the following configuration is adopted to achieve both "shortening the axial length of the solenoid 33" and "ensuring waterproofness with the O-ring 52". That is, in this embodiment, the axial length (axial dimension) of the solenoid 33 is shortened. In this case, as shown in Figure 4, the cylindrical portion 34C1 of the resin portion 34C that faces the seal groove 51D is extended toward the axial inner boundary side (rear side, anchor 41 side) of the bobbin 34B. That is, the boundary K between the resin portion 34C (cylindrical portion 34C1) and the bobbin 34B, in other words, the joint K between the resin portion 34C (cylindrical portion 34C1) located on the cover 51 side in the axial direction of the coil 34A and the bobbin 34B is provided on the axial inner boundary side (rear side, anchor 41 side) of the coil 34A. Furthermore, both axial ends 51D1 and 51D2 of the seal groove 51D are facing the resin part 34C (cylindrical part 34C1). In this embodiment, in order to ensure stable moldability of the resin part 34C (cylindrical part 34C1), an annular projection 34B1 is formed on the end face of one axial side (cover 51 side) of the bobbin 34B, projecting axially from this end face. In addition, a projection 34B2 is provided on the inner circumference of the bobbin 34B on the other axial side of the O-ring 52 (the anchor 41 side opposite the cover 51). These points will be explained in detail below.

[0073] First, as shown in Figure 1, the shock absorber 1 comprises an inner cylinder 4 and an outer cylinder 2 as cylinders, a piston 5, a piston rod 8, an annular oil chamber D that serves as a flow path (more specifically, the flow path between the annular oil chamber D and the reservoir chamber A), and a damping force adjustment valve 18 (pilot valve body 32, and consequently the main valve 23). The damping force adjustment valve 18 (pilot valve body 32, and consequently the main valve 23) is located in the flow path where the working fluid flow is generated by the expansion and contraction of the piston rod 8, that is, between the annular oil chamber D and the reservoir chamber A. The damping force adjustment valve 18 (pilot valve body 32, and consequently the main valve 23) is driven by a solenoid 33.

[0074] As shown in Figure 2, the damping force adjustment mechanism 17 includes a coil 34A, a bobbin 34B, a housing 36 as a storage section, an armature 48 as a movable element, an anchor 41 as a stator, a resin part 34C, a cover 51, a seal groove 51D and an O-ring 52 as a sealing member, and a damping force adjustment valve 18 (more specifically, a pilot valve body 32, and consequently, a main valve 23) as a control valve. The damping force adjustment valve 18 (pilot valve body 32, and consequently, the main valve 23) is controlled by the axial movement of the armature 48, which is fixed to the operating pin 49. As shown in Figure 3, the solenoid 33 includes a coil 34A, a bobbin 34B, a housing 36, an armature 48, an anchor 41, a resin part 34C, a cover 51, a seal groove 51D and an O-ring 52. The solenoid 33 also includes a yoke 39.

[0075] Coil 34A is wound in a ring shape and generates magnetic force (magnetic flux, magnetic field) when energized. Coil 34A is wound around bobbin 34B. Housing 36 is located on the inner circumference of bobbin 34B. Housing 36 extends in the direction of the winding axis of coil 34A and has an opening at one end (the lower side in the vertical direction of Figure 3). Housing 36 houses the armature 48 and is located radially between coil 34A and armature 48. The armature 48 is made of a magnetic material. The armature 48 is located inside (inner diameter side) of housing 36 and is movable in the direction of the winding axis of coil 34A. An anchor 41 is located on one side in the direction of movement of the armature 48 (the lower side in the vertical direction of Figure 3). That is, the anchor 41 is located opposite the opening of housing 36. Resin part 34C covers bobbin 34B. Cover 51 covers housing 36. The cover 51 constitutes the magnetic circuit. The seal groove 51D is provided in the cover 51. The O-ring 52 is fitted into the seal groove 51D. The yoke 39 has the anchor 41 attached to it.

[0076] The solenoid 33, together with the pilot valve body 32, constitutes a solenoid valve (pressure control valve). When current is passed through the coil 34A of the solenoid 33, a magnetic flux is generated, and this flux passes through a magnetic circuit consisting of the armature 48, anchor 41, cover 51, housing 36, and yoke 39, causing the armature 48 to be attracted to the anchor 41. This becomes the thrust of the armature 48, which controls the opening and closing of the pilot valve body 32.

[0077] As shown in Figure 4, in this embodiment, both axial ends of the seal groove 51D are formed in positions facing the resin portion 34C. That is, both axial ends 51D1 and 51D2 of the seal groove 51D are facing the resin portion 34C (cylindrical portion 34C1). Here, of the axial ends 51D1 and 51D2 of the seal groove 51D, the end (side wall) located closer to the coil 34A (towards the anchor 41) is designated as the inner end 51D1, and the end (side wall) located further away from the coil 34A (away from the anchor 41) is designated as the outer end 51D2. In this case, both the inner end 51D1 and the outer end 51D2 of the seal groove 51D face the resin portion 34C (cylindrical portion 34C1). In other words, the boundary K between the bobbin 34B and the resin part 34C (cylindrical part 34C1), that is, the joint K between the bobbin 34B on the cover 51 side and the resin part 34C (cylindrical part 34C1), is positioned closer to the coil 34A (on the anchor 41 side) than the inner end 51D1 of the seal groove 51D. This prevents the O-ring 52 fitted in the seal groove 51D from coming into contact with the boundary K between the bobbin 34B and the resin part 34C (cylindrical part 34C1).

[0078] The boundary K between the bobbin 34B and the resin part 34C has the following configuration. Specifically, the inner diameter dimension of the part of the bobbin 34B that faces the fitting cylindrical part 51A of the cover 51 and is located on the coil 34A side (anchor 41 side) of the seal groove 51D is "d". On the other hand, the inner diameter dimension of the cylindrical part 34C1 of the resin part 34C that faces the seal groove 51D is "D". In this case, the inner diameter dimension D of the resin part 34C (cylindrical part 34C1) is larger than the inner diameter dimension d of the bobbin 34B. Therefore, the boundary K between the bobbin 34B and the resin part 34C has a step 61. Even though there is a step 61 at the boundary K in this way, the edge (inner periphery) of this step 61 is located on the side closer to the coil 34A (anchor 41 side) than the inner end 51D1 of the seal groove 51D. Therefore, it is possible to prevent the O-ring 52 fitted in the seal groove 51D from coming into contact with the edge (inner periphery) of the step 61.

[0079] Furthermore, in this embodiment, an annular projection 34B1 is formed on one axial end of the bobbin 34B (the end on the cover 51 side). The annular projection 34B1 protrudes axially from the axial end face of the bobbin 34B on the cover 51 side all the way around the cover 51 side. This suppresses the occurrence of shrinkage (distortion) in the resin part 34C from around the annular projection 34B1 to the portion extending along the fitting cylindrical part 51A of the cover 51 (i.e., the cylindrical part 34C1). In other words, if the boundary K between the bobbin 34B and the resin part 34C (cylindrical part 34C1) is to be set on the inner side (anchor 41 side), the wall thickness of the resin part 34C (cylindrical part 34C1) will be uneven, which may cause shrinkage (distortion). However, by providing the annular projection 34B1 to make the wall thickness uniform, shrinkage (distortion) can be suppressed.

[0080] In this embodiment, a projection 34B2 is provided on the inner circumference of the bobbin 34B, on the other axial end side of the O-ring 52 (the anchor 41 side opposite the cover 51), having a circumferentially extending convex portion 34B3 and a concave portion 34B4. That is, as shown in Figure 5, a projection 34B2 is provided on the inner circumference side of the bobbin 34B, extending circumferentially and projecting radially inward. In this case, the projection 34B2 has a convex portion 34B3 projecting radially inward and a concave portion 34B4 as a notch recessed radially outward relative to the inner circumferential surface of the convex portion 34B3. In this case, the convex portion 34B3 is formed in a semi-circular arc shape extending approximately 180 degrees at two circumferential positions of the projection 34B2. The concave portion 34B4 is provided between the convex portions 34B3. In other words, the recesses 34B4 are provided at two or more positions (approximately equally spaced in the circumferential direction) of the projection 34B2. The projection 34B2 having such recesses 34B4 and protrusions 34B3 allows for the positioning of the bobbin 34B during the molding of the resin part 34C and for stabilizing the bobbin 34B within the mold.

[0081] The solenoid 33, damping force adjustment mechanism 17, and shock absorber 1 according to this embodiment have the configuration described above, and their operation will now be explained.

[0082] First, when the shock absorber 1 is installed in a vehicle such as an automobile, for example, the upper end (protruding end) of the piston rod 8 is attached to the vehicle body, and the mounting eye 3A on the bottom cap 3 is attached to the wheel. In addition, the solenoid 33 of the damping force adjustment mechanism 17 is connected to a control device (controller) installed on the vehicle body via electrical wiring cables (neither of which are shown).

[0083] When the vehicle is in motion, if vertical vibrations occur due to unevenness in the road surface, the piston rod 8 is displaced so as to extend and contract from the outer cylinder 2, and damping force can be generated by the damping force adjustment mechanism 17, etc., thereby mitigating the vibrations of the vehicle. At this time, the current value to the coil 34A of the solenoid 33 is controlled by the controller, and the opening pressure of the pilot valve body 32 is adjusted, thereby variably adjusting the damping force generated by the shock absorber 1.

[0084] For example, during the extension stroke of the piston rod 8, the movement of the piston 5 inside the inner cylinder 4 closes the compression-side check valve 7 of the piston 5. Before the disc valve 6 of the piston 5 opens, the oil in the rod-side oil chamber B is pressurized and flows into the oil passage 20B of the connecting pipe 20 of the damping force adjustment valve 18 through the oil hole 4A of the inner cylinder 4, the annular oil chamber D, and the connection port 12C of the intermediate cylinder 12. At this time, the amount of oil that has moved due to the piston 5 flows from the reservoir chamber A into the bottom-side oil chamber C by opening the extension-side check valve 16 of the bottom valve 13. When the pressure in the rod-side oil chamber B reaches the opening pressure of the disc valve 6, the disc valve 6 opens and relieves the pressure in the rod-side oil chamber B to the bottom-side oil chamber C.

[0085] In the damping force adjustment mechanism 17, the oil that flows into the oil passage 20B of the connecting pipe 20 passes through the central hole 21A of the valve member 21, the central hole 24B of the pilot pin 24, and the central hole 26C of the pilot body 26, as shown by arrow X in Figure 2, before the main valve 23 opens (in the low piston speed range), pushing open the pilot valve body 32 and flowing into the inside of the pilot body 26. The oil that has flowed into the inside of the pilot body 26 then flows through the space between the flange portion 32A of the pilot valve body 32 and the disc valve 29, the oil passage 30A of the retaining plate 30, the notch 31A of the cap 31, and the oil chamber 19C of the valve case 19 to the reservoir chamber A. As the piston speed increases, when the pressure in the oil passage 20B of the connecting pipe 20, i.e., the pressure in the rod-side oil chamber B, reaches the opening pressure of the main valve 23, the oil that has flowed into the oil passage 20B of the connecting pipe 20 passes through the oil passage 21B of the valve member 21, as shown by arrow Y in Figure 2, pushes open the main valve 23, and flows through the oil chamber 19C of the valve case 19 to the reservoir chamber A.

[0086] On the other hand, during the compression stroke of the piston rod 8, the movement of the piston 5 inside the inner cylinder 4 opens the compression-side check valve 7 of the piston 5, and the extension-side check valve 16 of the bottom valve 13 closes. Before the bottom valve 13 (disc valve 15) opens, the oil from the bottom-side oil chamber C flows into the rod-side oil chamber B. At the same time, the amount of oil equivalent to the amount the piston rod 8 has entered inside the inner cylinder 4 flows from the rod-side oil chamber B to the reservoir chamber A via the damping force adjustment valve 18, following the same path as during the extension stroke. When the pressure inside the bottom-side oil chamber C reaches the opening pressure of the bottom valve 13 (disc valve 15), the bottom valve 13 (disc valve 15) opens, relieving the pressure in the bottom-side oil chamber C to the reservoir chamber A.

[0087] As a result, during the extension and compression strokes of the piston rod 8, before the main valve 23 of the damping force adjustment valve 18 opens, a damping force is generated by the orifice 24C of the pilot pin 24 and the opening pressure of the pilot valve body 32. After the main valve 23 opens, a damping force is generated according to the opening degree of the main valve 23. In this case, by adjusting the opening pressure of the pilot valve body 32 by energizing the coil 34A of the solenoid 33, the damping force can be directly controlled regardless of the piston speed.

[0088] Specifically, reducing the current supplied to coil 34A and decreasing the thrust of armature 48 lowers the opening pressure of pilot valve body 32, generating a soft damping force. On the other hand, increasing the current supplied to coil 34A and increasing the thrust of armature 48 increases the opening pressure of pilot valve body 32, generating a hard damping force. At this time, the opening pressure of pilot valve body 32 changes the internal pressure of the back pressure chamber 27, which is connected to it via the oil passage 25 upstream of it. As a result, by controlling the opening pressure of pilot valve body 32, the opening pressure of the main valve 23 can be adjusted simultaneously, widening the adjustment range of the damping force characteristics.

[0089] Furthermore, if the thrust of the armature 48 is lost due to a break in the coil 34A or the like, the pilot valve body 32 is retracted by the return spring 28 (displaced away from the valve seat 26E), and the flange portion 32A of the pilot valve body 32 comes into contact with the disc valve 29. In this state, damping force can be generated by the opening pressure of the disc valve 29, and the necessary damping force can be obtained even in the event of a malfunction such as a broken coil.

[0090] In this embodiment, the inner end 51D1 and outer end 51D2, which are the axial ends of the seal groove 51D, are both formed in positions facing the resin part 34C (cylindrical part 34C1). Therefore, the O-ring 52 installed in the seal groove 51D can be brought into contact with the resin part 34C (cylindrical part 34C1). That is, it is possible to prevent the O-ring 52 installed in the seal groove 51D from reaching the bobbin 34B. This prevents the O-ring 52 from coming into contact with the boundary K between the resin part 34C (cylindrical part 34C1) and the bobbin 34B. Therefore, it is possible to ensure the durability of the O-ring 52, ensure good adhesion with the resin part 34C (cylindrical part 34C1), and prevent damage to the O-ring 52, thereby improving the waterproofing performance of the O-ring 52.

[0091] According to this embodiment, an annular projection 34B1 is formed on the end (end face) of the bobbin 34B that is on the cover 51 side, which is one of the axial ends of the bobbin 34B. Therefore, even if the resin part 34C (cylindrical part 34C1) is extended toward the anchor 41 side along the axial direction of the bobbin 34B in order to bring both the inner end 51D1 and the outer end 51D2 of the seal groove 51D toward the resin part 34C (cylindrical part 34C1), it is possible to suppress shrinkage (distortion) in that part, that is, in the cylindrical part 34C1 which is the part of the resin part 34C that faces the seal groove 51D. In other words, by forming an annular projection 34B1 on the end face of the bobbin 34B on the cover 51 side, the wall thickness of the resin part 34C can be made constant from the part that covers the area around the annular projection 34B1 of the bobbin 34B to the part that faces the seal groove 51D (i.e., the cylindrical part 34C1). This makes it possible to suppress shrinkage (distortion) in the portion of the resin part 34C facing the seal groove 51D (cylindrical part 34C1).

[0092] According to the embodiment, a projection 34B2 is provided on the anchor 41 side of the inner circumference of the bobbin 34B, which is on the other axial end side of the O-ring 52, having a circumferentially extending convex portion 34B3 and a concave portion 34B4. This allows the bobbin 34B to be stabilized in the mold during molding. Specifically, the convex portion 34B3 of the projection 34B2 is sandwiched by the mold, which suppresses the axial movement of the bobbin 34B. In addition, the concave portion 34B4 of the projection 34B2 is fitted with a part of the mold, which suppresses the circumferential (rotational) movement of the bobbin 34B. As a result, the bobbin 34B can be stabilized in the mold, ensuring molding stability.

[0093] In this embodiment, the example described was one in which the recessed portion 41B of the anchor 41 is made into a flat bottom surface, and the opposing portion of the armature 48 facing this recessed portion 41B is also made flat. However, the invention is not limited to this, and for example, an intermediate protrusion that projects in a triangular cross-section toward the armature may be provided in the recessed portion of the anchor, and a groove in a triangular cross-section may be provided in the armature corresponding to this intermediate protrusion.

[0094] In the embodiment, the case in which the housing 36 and the cylinder 44, and the cylinder 44 and the yoke 39 are joined via brazing material was described as an example. However, the embodiment is not limited to this, and for example, the housing 36 and the cylinder 44, and the cylinder 44 and the yoke 39 may be joined by welding.

[0095] In this embodiment, the case in which the anchor 41 is fixed by press-fitting into the fixing hole 39A of the yoke 39 was described as an example. However, the invention is not limited to this, and the anchor may be fixed inside the yoke using, for example, screw fastening means such as screws, crimping means, etc.

[0096] In this embodiment, the case in which the anchor 41 and the yoke 39 are configured as separate components was used as an example. However, the invention is not limited to this, and for example, the anchor and the yoke may be configured as a single unit.

[0097] In this embodiment, the example described was one in which one side of the cylinder 44 is fixed to the yoke 39. However, the invention is not limited to this, and for example, one side of the cylinder (joint) may be fixed to an anchor.

[0098] In the embodiment, an example was described in which the yoke 39 is provided with a cylindrical portion 39H on the other side, and the tip side (the other side in the axial direction) of the cylindrical portion 39H is fixed to the outer circumference of the cover 51 by a crimping portion 39J. However, the embodiment is not limited to this, and for example, the annular portion of the yoke and the cylindrical portion on the other side may be formed separately, and the cylindrical portion on the other side may be formed integrally with the cover portion.

[0099] In this embodiment, the case in which the solenoid 33 is configured as a proportional solenoid was used as an example. However, it is not limited to this, and for example, it may be configured as an ON / OFF type solenoid.

[0100] In the embodiment, a double-tube type shock absorber 1 consisting of an outer tube 2 and an inner tube 4 was described as an example. However, it is not limited to this, and may also be used in a damping force adjustable shock absorber consisting of a single-tube type cylindrical member (cylinder), for example.

[0101] In this embodiment, the example described was when the solenoid 33 is used as a variable damping force actuator for the shock absorber 1, that is, when the pilot valve body 32, which constitutes the pilot valve of the damping force adjustment valve 18, is the object to be driven by the solenoid 33. However, the solenoid is not limited to this, and can be widely used as an actuator incorporated into various mechanical devices, such as valves used in hydraulic circuits, that is, as a drive device that drives an object to be driven linearly.

[0102] According to the embodiments described above, the axial ends of the seal grooves are all formed in positions facing the resin portion. Therefore, the seal member installed in the seal groove can be brought into contact with the resin portion. That is, it is possible to prevent the seal member installed in the seal groove from reaching the bobbin. This prevents the seal member from coming into contact with the boundary between the resin portion and the bobbin. Therefore, it is possible to ensure the durability of the seal member, ensure adhesion with the resin portion, prevent damage to the seal member, and improve the waterproofness of the seal member.

[0103] According to this embodiment, an annular projection is formed at one end of the bobbin in the axial direction. Therefore, even if the resin portion is extended along the axial direction of the bobbin so that both axial ends of the seal groove face the resin portion, shrinkage (distortion) in the portion of the resin portion facing the seal groove can be suppressed. In other words, by forming an annular projection at one end of the bobbin in the axial direction, the thickness of the resin portion can be made constant from the portion covering the annular projection of the bobbin to the portion facing the seal groove. This suppresses the occurrence of shrinkage (distortion) in the resin portion (the portion facing the seal groove).

[0104] According to the embodiment, a projection is provided on the inner circumference of the bobbin on the axial side opposite the sealing member, having a convex portion and a concave portion extending in the circumferential direction. This allows the bobbin to be stabilized in the mold during molding. Specifically, the convex portion of the projection is sandwiched by the mold, thereby suppressing axial movement of the bobbin. Furthermore, the concave portion of the projection is fitted with a part of the mold, thereby suppressing circumferential (rotational) movement of the bobbin. This allows the bobbin to be stabilized in the mold. [Explanation of Symbols]

[0105] 1 Buffer (damping force adjustable buffer) 2. Outer cylinder 4. Inner cylinder 5 pistons 8 Piston Rods 17 Damping force adjustment mechanism 18 Damping force adjustment valve 32 Pilot valve body (control valve) 33 Solenoid 34A coil 34B bobbin 34B1 Annular protrusion 34B2 Protrusion 34B3 Convex part 34B4 recess 34C Resin part 36 Housing (storage area) 41 Anchor (stator) 48. Amateur (movable element) 51 Cover 51D seal groove 51D1 Inner end (axial end) 51D2 Outer end (axial end) 52 O-ring (sealing component)

Claims

1. A solenoid, said solenoid is A coil that is wound in a ring shape and generates magnetic force when an electric current is passed through it, A bobbin around which the coil is wound, A housing portion is arranged on the inner circumference of the bobbin, extends in the direction of the winding axis of the coil, and has an open end, The storage section includes a movable element that is movable in the direction of the winding axis of the coil, A stator provided at a position opposite the opening of the storage compartment, The resin part covering the bobbin, A cover that covers the aforementioned storage compartment, A seal groove provided in the cover and a seal member fitted into the seal groove, It has, The axial end of the seal groove has an inner end that forms a side wall located closer to the coil and an outer end that forms a side wall located further away from the coil. Both the inner end and the outer end are formed in positions facing the resin portion. The joint between the bobbin and the resin part, which forms the boundary between the bobbin and the resin part, is located closer to the coil than the inner end of the solenoid.

2. The solenoid according to claim 1, wherein an annular projection is formed at one end of the bobbin in the axial direction.

3. The solenoid according to claim 1, wherein a projection having a convex portion and a concave portion extending in the circumferential direction is provided on the inner circumference of the bobbin, on the other end in the axial direction from the sealing member.

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