JP2024048011A - solenoid - Google Patents

Abstract

[Problem] To provide a solenoid capable of improving the waterproofing of a sealing member. [Solution] A molded coil 34 constituting a solenoid 33 includes a coil 34A, a bobbin 34B, and a resin portion 34C. A housing 36 is disposed on the inner circumferential side of the molded coil 34. The housing 36 is covered by a cover 51. An O-ring 52 is provided between a fitting cylindrical portion 51A of the cover 51 and the resin portion 34C of the molded coil 34 to provide a seal therebetween. The O-ring 52 is fitted in a seal groove 51D provided in the cover 51. Axial ends 51D1, 51D2 of the seal groove 51D are both formed in positions facing a cylindrical portion 34C1 of the resin portion 34C. [Selected Figure] Figure 4

Description

This disclosure relates to solenoids used, for example, in the damping force adjustment mechanism of a damping force adjustable shock absorber.

Vehicles such as four-wheeled automobiles are provided with shock absorbers (dampers) between the vehicle body (sprung) and each wheel (unsprung). A known shock absorber for such vehicles is a damping force adjustable hydraulic shock absorber, which variably adjusts the damping force according to the driving conditions, vehicle behavior, etc. The damping force adjustable hydraulic shock absorber constitutes a semi-active suspension for the vehicle.

In a damping force adjustable hydraulic shock absorber, the generated damping force is variably adjusted, for example, by adjusting the opening pressure of a damping force adjustment valve using a damping force variable actuator (damping force adjustment mechanism). For example, a solenoid is used as the damping force variable actuator. Here, Patent Document 1 describes a solenoid that includes a coil, a bobbin around which the coil is wound, a storage section that is disposed on the inner periphery of the bobbin and has one open end, a mover that is disposed within the storage section so as to be movable in the direction of the coil's winding axis, a stator that is disposed in a position facing the opening of the storage section, and a cover that covers the side opposite the opening of the storage section in the axial direction.

International Publication No. 2021/215148

The solenoid of Patent Document 1 has a seal groove in the cover, and a seal member (O-ring) is attached to this seal groove. In this case, the seal groove faces the boundary between the bobbin and the resin part (exterior resin) that covers the bobbin. That is, one side of the seal groove in the axial direction (the periphery of the side wall on the movable member side of the pair of side walls that make up the seal groove) faces the bobbin. For this reason, the seal member attached to the seal groove abuts against the boundary between the bobbin and the resin part, which may lead to a decrease in the durability of the seal member. In addition, if there is a step at the boundary between the bobbin and the resin part, this may lead to a decrease in the adhesion of the seal member and damage due to contact between the seal member and the step, and the waterproofness may be reduced. And if the waterproofness cannot be sufficiently ensured, it may lead to a short circuit due to the intrusion of water, for example.

The objective of one embodiment of the present invention is to provide a solenoid that can improve the waterproofing of the sealing member.

One embodiment of the present invention is a solenoid, which includes a coil wound in a circular shape and generating a magnetic force when current is applied, a bobbin around which the coil is wound, a storage section disposed on the inner circumference of the bobbin, extending in the direction of the winding axis of the coil and having an open end, a mover provided in the storage section so as to be movable in the direction of the winding axis of the coil, a stator provided in a position facing the opening of the storage section, a resin section that covers the bobbin, a cover that covers the storage section, a seal groove provided in the cover, and a seal member that is fitted in the seal groove, and the axial ends of the seal groove are both formed in positions facing the resin section.

According to one embodiment of the present invention, the waterproofing of the sealing member can be improved.

1 is a vertical cross-sectional view showing a damping force adjustable shock absorber incorporating a solenoid according to an embodiment; 2 is an enlarged cross-sectional view showing the damping force adjustment mechanism in FIG. 1 . FIG. 3 is an enlarged cross-sectional view showing a solenoid in FIG. 2 . FIG. 4 is an enlarged view of part (IV) in FIG. FIG. 2 is a plan view of the bobbin as viewed from the cover side.

The following describes an example of a solenoid according to an embodiment used in a damping force adjustment mechanism of a damping force adjustable shock absorber installed in a vehicle such as a four-wheeled automobile, with reference to the attached drawings.

First, a damping force adjustable hydraulic shock absorber 1 incorporating a solenoid 33 according to this embodiment will be described. In FIG. 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 that uses a solenoid 33 as a drive source. That is, the shock absorber 1 as a damping force adjustable shock absorber is configured to include an outer cylinder 2 and an inner cylinder 4 as cylinders, a piston 5, a piston rod 8, and the damping force adjustment mechanism 17.

The shock absorber 1, which is a hydraulic shock absorber, has a bottomed cylindrical outer cylinder 2 that forms an outer shell. The lower end of the outer cylinder 2 is closed by a bottom cap 3 using welding or the like. The upper end of the outer cylinder 2 forms 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 cylinder 4. Meanwhile, an opening 2B is formed on the lower side of the outer cylinder 2, concentric with the connection port 12C of the intermediate cylinder 12. A damping force adjustment mechanism 17 is attached to the lower side of the outer cylinder 2, facing the opening 2B. The bottom cap 3 is provided with a mounting eye 3A that is attached, for example, to the wheel side of the vehicle.

The inner cylinder 4 is provided coaxially with the outer cylinder 2 within 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. Oil (hydraulic fluid) is sealed inside the outer cylinder 2 and inner cylinder 4 as a cylinder. The hydraulic fluid is not limited to oil, and may be, for example, water mixed with an additive.

A ring-shaped reservoir chamber A is formed between the inner cylinder 4 and the outer cylinder 2. Gas is sealed in the reservoir chamber A along with oil. This gas may be air at atmospheric pressure, or compressed nitrogen gas or other gases. The reservoir chamber A compensates for the advancement and withdrawal of the piston rod 8. An oil hole 4A is drilled radially at a midpoint in the length direction (axial direction) of the inner cylinder 4, which constantly connects the rod-side oil chamber B to the ring-shaped oil chamber D.

The piston 5 is slidably disposed within the inner cylinder 4. The piston 5 is inserted into the inner cylinder 4, dividing (dividing) 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). The piston 5 has multiple oil passages 5A, 5B formed at intervals in the circumferential direction, which allow communication between the rod-side oil chamber B and the bottom-side oil chamber C.

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

The upper end surface of the piston 5 is provided with a compression check valve 7 which opens when the piston 5 slides downward during the contraction stroke of the piston rod 8 and closes otherwise. The check valve 7 allows oil in the bottom oil chamber C to flow through each oil passage 5B toward the rod oil chamber B, and prevents 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 to soft, and does not substantially generate a damping force. This "substantially not generating a damping force" means a force below the friction of the piston 5 and seal 10, and does not affect the movement of the vehicle.

The piston rod 8 extends in the axial direction (vertical direction in FIG. 1) inside the inner cylinder 4. The lower end of the piston rod 8 is inserted into the inner cylinder 4. The piston rod 8 is fixed to the piston 5 by a nut 8A or the like. The upper end of the piston rod 8 protrudes outside the outer cylinder 2 and the inner cylinder 4 via a rod guide 9. That is, the lower side (lower end) of the piston rod 8, which is one side (one end), is connected to the piston 5, and the upper side (upper end) of the piston rod 8, which is the other side (other end), extends outside the inner cylinder 4 and the outer cylinder 2. The lower end of the piston rod 8 may be further extended to protrude outward from the bottom part (e.g., bottom cap 3) side, making it a so-called double rod.

A stepped cylindrical rod guide 9 is provided at the upper end of the inner cylinder 4. The rod guide 9 positions the upper part of the inner cylinder 4 at the center of the outer cylinder 2, and guides the piston rod 8 on its inner periphery so that it can slide in the axial direction. An annular seal 10 is provided between the rod guide 9 and the crimped portion 2A of the outer cylinder 2. The seal 10 is made, for example, by baking an elastic material such as rubber onto a metal circular plate with a hole in the center through which the piston rod 8 is inserted. The inner periphery of the elastic material of the seal 10 slides against the outer periphery of the piston rod 8, thereby sealing between the piston rod 8 and the seal 10.

The seal 10 has a lip seal 10A formed on the underside as a check valve that extends to contact the rod guide 9. The lip seal 10A is disposed between the oil sump chamber 11 and the reservoir chamber A. The lip seal 10A allows the oil and liquid in the oil sump chamber 11 to flow toward the reservoir chamber A through the return passage 9A of the rod guide 9, and prevents flow in the opposite direction.

Between the outer cylinder 2 and the inner cylinder 4, an intermediate cylinder 12 made of a cylindrical body is arranged. The intermediate cylinder 12 is attached, for example, to the outer periphery 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, which extends so as to surround the entire outer periphery of the inner cylinder 4. The annular oil chamber D is an oil chamber independent of the reservoir chamber A. The annular oil chamber D is constantly connected to the rod side oil chamber B through a radial oil hole 4A formed in the inner cylinder 4. The annular oil chamber D forms part of a flow path in which a flow of the working liquid occurs due to the movement of the piston rod 8. A connection port 12C is provided at the lower end side of the intermediate cylinder 12 to which the connection tube 20 of the damping force adjustment valve 18 is attached.

The bottom valve 13 is located at the lower end of the inner cylinder 4 and is provided between the bottom cap 3 and the inner cylinder 4. The bottom valve 13 is composed of a valve body 14 that separates (divides) the reservoir chamber A and the bottom oil chamber C between the bottom cap 3 and the inner cylinder 4, a reduction side disk valve 15 provided on the lower surface of the valve body 14, and an extension side check valve 16 provided on the upper surface of the valve body 14. The valve body 14 has oil passages 14A and 14B formed at intervals in the circumferential direction, which allow communication between the reservoir chamber A and the bottom oil chamber C.

When the piston 5 slides downward during the retraction stroke of the piston rod 8, the reduction-side disk valve 15 opens when the pressure in the bottom-side oil chamber C exceeds the relief set pressure, and relieves the pressure at this time to the reservoir chamber A side via 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 to hard.

The extension check valve 16 opens when the piston 5 slides upward during the extension stroke of the piston rod 8, and closes otherwise. The check valve 16 allows oil in the reservoir chamber A to flow through each oil passage 14B toward the bottom oil chamber C, and prevents 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 does not actually generate any damping force.

Next, the damping force adjustment mechanism 17 for variably adjusting the damping force generated by the shock absorber 1 will be described with reference to FIG. 2 in addition to FIG. 1.

The damping force adjustment mechanism 17 generates a damping force by controlling the flow of hydraulic fluid (oil) generated by the sliding of the piston 5 inside the cylinder (inner tube 4), and variably adjusts the damping force generated by the shock absorber 1. Note that the damping force adjustment mechanism 17 in FIG. 2 shows a state in which the armature 48, operating pin 49, and pilot valve body 32 move to the left in FIG. 2 by externally energizing 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 FIG. 2 shows a closed valve state in which the pilot valve body 32 is seated on the valve seat portion 26E of the pilot body 26.

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

In this way, the damping force adjustment mechanism 17 generates a damping force by controlling the flow of the working fluid (oil) caused by the sliding of the piston 5 inside the inner cylinder 4. To this end, the damping force adjustment mechanism 17 is configured to include a damping force adjustment valve 18 and a solenoid 33. The damping force adjustment valve 18 variably controls the flow of oil from the annular oil chamber D to the reservoir chamber A, thereby generating a damping force with hard or soft characteristics. The damping force adjustment valve 18 is driven by the solenoid 33.

That is, the damping force adjustment valve 18 is a valve whose opening and closing operation is adjusted by the solenoid 33, and is provided in a flow path (for example, between the annular oil chamber D and the reservoir chamber A) where the flow of working liquid occurs due to the movement (expansion 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 therefore the main valve 23). In this case, the valve opening pressure of the damping force adjustment valve 18 (pilot valve body 32, and therefore the main valve 23) is adjusted by the solenoid 33 used as a damping force variable actuator, whereby the generated damping force is variably controlled to have hard or soft characteristics.

As shown in Figs. 1 and 2, the damping force adjustment valve 18 includes a valve case 19, a connecting pipe 20, and a valve member 21. The valve case 19 is formed in a generally cylindrical shape, with its base end fixed to the periphery of 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 formed as an annular flange portion 20A that is disposed with a gap inside the valve case 19. The valve member 21 abuts against the flange portion 20A of the connecting pipe 20.

As shown in FIG. 2, the base end side of the valve case 19 is an annular inner flange portion 19A extending radially inward. The tip end side of the valve case 19 is a male thread portion 19B onto which a lock nut 53 is screwed to connect the valve case 19 to the yoke 39 (one side cylindrical portion 39G) of the solenoid 33. Between the inner peripheral surface of the valve case 19 and the outer peripheral surface of the valve member 21, and further between the inner peripheral surface of the valve case 19 and the outer peripheral surface of the pilot body 26, etc., an annular oil chamber 19C that is constantly in communication with the reservoir chamber A is formed. In addition to connecting the valve case 19 and the solenoid 33 with the lock nut 53, for example, the tip end side of the valve case may be crimped to the yoke of the solenoid (a configuration without using a lock nut).

The inside of the connecting pipe body 20 has an oil passage 20B, one side of which is connected to the annular oil chamber D, and the other side of which extends to the position of the valve member 21. A circular spacer 22 is sandwiched between the flange portion 20A of the connecting pipe body 20 and the inner flange portion 19A of the valve case 19. The spacer 22 has a plurality of notches 22A extending radially, which serve as radial oil passages to connect the oil chamber 19C and the reservoir chamber A. In this embodiment, the spacer 22 is configured to have notches 22A for forming oil passages. However, instead of the spacer 22, notches (grooves) for forming oil passages may be provided radially in the inner flange portion 19A of the valve case 19.

The valve member 21 has a central hole 21A located at the center in the radial direction and extending in the axial direction. The valve member 21 also has a plurality of oil passages 21B spaced apart in the circumferential direction around the central hole 21A. One side (left side in Figs. 1 and 2) of each oil passage 21B is always connected to the oil passage 20B side of the connecting pipe body 20. The other side (right side in Figs. 1 and 2) of the end face of the valve member 21 has 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 is seated and released. Each oil passage 21B of the valve member 21 serves as a flow path through which pressurized oil flows at a flow rate according to the opening degree of the main valve 23 between the oil passage 20B of the connecting pipe body 20 connected to the annular oil chamber D and the oil chamber 19C of the valve case 19 connected to the reservoir chamber A.

The main valve 23 is composed of a disk 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 is seated on and removed from the annular valve seat 21D of the valve member 21. An elastic seal 23A is fixed to the outer circumference of the back side of the main valve 23 by baking or other means. The main valve 23 opens when it receives pressure from the oil passage 21B side (annular oil chamber D side) of the valve member 21 and leaves 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 pressure oil flowing in the direction of the arrow Y at this time is variably adjusted according to the opening degree of the main valve 23.

The pilot pin 24 is formed in a stepped cylindrical shape, with an annular large diameter portion 24A in the axial middle portion. The pilot pin 24 has a central hole 24B extending axially on the inner periphery side. A small diameter hole (orifice 24C) is formed in one end portion (the end portion on the connection pipe body 20 side) of the central hole 24B. One end side (the left end side in Figures 1 and 2) of the pilot pin 24 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 holds the main valve 23 between itself and the valve member 21.

The other end side of the pilot pin 24 (the right end side in Figs. 1 and 2) is fitted into the central hole 26C of the pilot body 26. An oil passage 25 extending in the axial direction is formed between the central hole 26C of the pilot body 26 and the other end side of the pilot pin 24. This oil passage 25 is connected to a back pressure chamber 27 formed between the main valve 23 and the pilot body 26. In other words, a plurality of oil passages 25 extending in the axial direction are provided in the circumferential direction on the side surface of the other end side of the pilot pin 24, and other circumferential positions are press-fitted into the central hole 26C of the pilot body 26.

The pilot body 26 is formed as a generally bottomed tubular 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 has a central hole 26C into which the other end of the pilot pin 24 is fitted. A protruding tubular portion 26D that is located on the outer diameter side and protrudes toward the valve member 21 over the entire circumference is integrally provided on one end side (the left end side in Figs. 1 and 2) of the bottom portion 26B of the pilot body 26. The elastic seal 23A of the main valve 23 is liquid-tightly fitted to the inner peripheral surface of the protruding tubular 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 a pressure (internal pressure, pilot pressure) that presses the main valve 23 in the valve closing direction, i.e., in the direction in which the main valve 23 is seated on the annular valve seat 21D of the valve member 21.

At the other end side (the right end side in Figs. 1 and 2) of the bottom 26B of the pilot body 26, a valve seat 26E on which the pilot valve element 32 sits and leaves is provided so as to surround the central hole 26C. Inside the cylindrical portion 26A of the pilot body 26, there are arranged a return spring 28 that biases the pilot valve element 32 in a direction away from the valve seat 26E of the pilot body 26, a disk valve 29 that constitutes a fail-safe valve when the solenoid 33 is in a non-energized state (when the pilot valve element 32 is farthest from the valve seat 26E), a retaining plate 30 with an oil passage 30A formed on the central side, and the like.

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

The pilot valve element 32 and the pilot body 26 form a pilot valve (control valve). The pilot valve element 32 is formed in a stepped cylindrical shape. The tip of the pilot valve element 32, i.e., the tip that seats and separates from the valve seat portion 26E of the pilot body 26, is tapered. An operating pin 49 of the solenoid 33 is fitted and fixed inside the pilot valve element 32, and the valve opening pressure of the pilot valve element 32 is adjusted according to the supply of electricity to the solenoid 33.

That is, the pilot valve (pilot body 26 and pilot valve element 32) as a control valve is controlled by the axial movement of the actuating pin 49 of the solenoid 33 (more specifically, the armature 48 fixed to the actuating pin 49). A flange portion 32A that serves as a spring bearing is formed around the entire circumference on the base end side of the pilot valve element 32. When the solenoid 33 is in a non-energized state, that is, when the pilot valve element 32 is displaced to the fully open position where it is farthest from the valve seat portion 26E, the flange portion 32A comes into contact with the inner circumference of the disk valve 29, thereby forming a fail-safe valve.

Next, the solenoid 33, which constitutes the damping force adjustment mechanism 17 together with the damping force adjustment valve 18, will be described with reference to FIG. 3 in addition to FIG. 1 and FIG. 2. Note that in FIG. 3, the right side in the left-right direction of FIG. 2 is numbered with the top side. In other words, the left-right direction in FIG. 1 and FIG. 2 corresponds to the up-down direction in FIG. 3 and FIG. 4.

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

The molded coil 34 is formed into a substantially cylindrical shape by winding the coil 34A around the bobbin 34B (coil bobbin) and covering (molding) the coil 34A with a resin part 34C made of thermoplastic resin or thermosetting resin. The resin part 34C is a resin member and corresponds to the exterior resin of the coil 34A. A cable outlet part 34E that protrudes axially or radially outward is provided at a portion of the circumference of the molded coil 34. An electric cable (not shown) is connected to the cable outlet part 34E. The coil 34A of the molded coil 34 is wound around the bobbin 34B in a circular shape, and becomes an electromagnet to generate a magnetic field (magnetic force) when power is supplied (energized) from an external cable.

A seal groove 34D is formed around the entire circumference of the resin portion 34C of the molded coil 34 on the side (one end surface in the axial direction) facing the yoke 39 (annular portion 39B). An O-ring 35 is fitted in 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 makes it possible to prevent dust containing rainwater or muddy water from entering the cylindrical protrusion portion 39C side of the yoke 39 through the gap between the yoke 39 and the molded coil 34.

The coil member used in this embodiment is a molded coil 34 consisting of a coil 34A, a bobbin 34B, and a resin portion 34C. In other words, the coil member, which is integrally formed including the coil 34A, is configured such that the outer periphery of the coil 34A is covered with the resin portion 34C by molding (overmolding) a resin material from above (the outer periphery) in a state where the coil 34A is wound around the bobbin 34B made of an electrically insulating material.

The housing 36 constitutes a first fixed core (storage section) arranged on the inner periphery side of the molded coil 34 (i.e., the inner periphery 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 mechanical construction (S10C). The housing 36 is composed of a storage tube section 36A, a lid section 36B, and a small diameter tube section 36C. The storage tube section 36A extends in the winding axis direction of the molded coil 34 (coil 34A) and is open at one end side (left side in FIG. 2, lower side in FIG. 3). The lid section 36B closes the other end side (right side in FIG. 2, upper side in FIG. 3) of the storage tube section 36A. The small diameter tube section 36C is located on the opening side (one side) of the storage tube section 36A and is formed to reduce the outer diameter of the storage tube section 36A.

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 storage 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 stored within the storage cylindrical portion 36A so that it can move axially. That is, one end of the housing 36 in the axial direction is open, and the armature 48 is stored within it. 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.

On the other hand, the lid portion 36B of the housing 36 is formed integrally with the storage cylinder portion 36A as a covered cylinder that closes the storage cylinder portion 36A from the other axial side. The outer diameter of the lid portion 36B is stepped and smaller than the outer diameter of the storage cylinder portion 36A. The fitting cylinder portion 51A of the cover 51 is fitted to the outer periphery of the lid portion 36B. The housing 36 is also formed with 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 located further back than the bush mounting hole portion 37A and formed with a small diameter. A first bush 38 is provided in the bush mounting hole portion 37A as a bearing (first bearing) for slidably supporting the operating pin 49.

The lid portion 36B of the housing 36 is disposed so that the other end surface faces the lid plate 51B of the cover 51 with an axial gap therebetween. This axial gap serves to prevent 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. 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, for example, a rigid metal material, a ceramic material, or a fiber-reinforced resin material, rather than a magnetic material. The joint between the storage cylinder portion 36A and the lid portion 36B of the housing 36 is located in consideration of the transfer of magnetic flux.

The yoke 39 is provided on one side of the armature 48 in the moving direction. The yoke 39 is a magnetic member that forms a magnetic circuit (magnetic path) with the housing 36 over the inner and outer circumferential sides of the molded coil 34 (coil 34A). That is, the yoke 39 is formed using a magnetic material (magnetic body) like the housing 36. The yoke 39 is configured to include 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) and has a stepped fixing hole 39A on its inner circumferential side, and a cylindrical protrusion portion 39C that protrudes cylindrically along the axial direction of the fixing hole 39A from the inner circumferential side of the annular portion 39B toward the other axial side (coil 34A side). The cylindrical protrusion portion 39C forms a protrusion (cylindrical portion) for joining with the cylinder 44, and the cylinder 44 is inserted into the inner diameter side of the cylindrical protrusion portion 39C.

In other words, the yoke 39 has a fixing hole 39A, and the anchor 41 is disposed within the fixing hole 39A. An inward flange 39D that protrudes inwardly around the entire circumference is provided within the fixing hole 39A. An end face (one end face) of one axial side of the cylinder 44 abuts against the side face (side face on the coil 34A side) of the inward flange 39D. The outer periphery of one axial side of the cylinder 44 is fitted into the inner periphery of the yoke 39, i.e., the inner surface of the fixing hole 39A (in other words, the inner periphery of the cylindrical protrusion 39C).

The yoke 39 is formed as an integral part including a cylindrical one-side tube portion 39G extending from the outer periphery of the annular portion 39B toward one axial side (the main valve 23 side), an other-side tube portion 39H extending from the outer periphery of the annular portion 39B toward the other axial side (the cover 51 side) and formed to surround the molded coil 34 from the radial outside, and a crimp portion 39J provided at the tip of the other-side tube portion 39H and holding the flange portion 51C of the cover 51 in a non-removable state. The other-side tube portion 39H of the yoke 39 is provided with a notch 39K for exposing the cable outlet portion 34E of the molded coil 34 to the outside of the other-side tube portion 39H.

Between the one-side cylinder portion 39G and the other-side cylinder portion 39H of the yoke 39, engagement recesses 39L having a semicircular cross section are provided (along the entire circumference, or at multiple locations spaced apart in the circumferential direction) so as to open onto the outer circumferential surface of the yoke 39. A lock nut 53 screwed onto the valve case 19 engages with the engagement recesses 39L via a retaining ring 54 (Fig. 2). Furthermore, a seal groove 39M is provided along the entire circumference on the outer circumferential surface of the one-side cylinder portion 39G. An O-ring 40 (Fig. 2) is fitted into the seal groove 39M. The O-ring 40 provides a liquid-tight seal between the yoke 39 (one-side cylinder portion 39G) and the valve case 19 of the damping force adjustment valve 18.

The anchor 41 is provided on one side of the movement direction of the armature 48. The anchor 41 is arranged 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 the like. The anchor 41 is formed in a shape that fills the fixing hole 39A of the yoke 39 from the inside, using a magnetic material (magnetic body) such as low carbon steel or carbon steel for mechanical construction (S10C) like the housing 36 (first fixed core) and the yoke 39. The anchor 41 is formed as a short cylindrical ring-shaped body with a through hole 41A extending in the axial direction at the center. One axial side surface of the anchor 41 (the surface facing the cap 31 in the axial direction shown in FIG. 2) is formed to be a flat surface like one side surface of the ring-shaped portion 39B of the yoke 39.

A circular recessed portion 41B is recessed on the other axial side of the anchor 41 (the other side facing the armature 48 in the axial direction) so as to be coaxial with the storage cylinder portion 36A of the housing 36. The recessed portion 41B is formed as a circular groove with a diameter slightly larger than that of the armature 48 so that the armature 48 can be inserted inside and out by magnetic force. For this reason, a cylindrical outer peripheral protrusion 41C is provided on the other side of the anchor 41. The outer peripheral surface on the opening side of the outer peripheral protrusion 41C is formed as a conical surface so that the magnetic characteristics between the anchor 41 and the armature 48 are linear (straight-line) characteristics. In other words, the outer peripheral protrusion 41C, also called a corner portion, protrudes in a cylindrical shape from the outer peripheral side of the anchor 41 toward the other axial side. The outer peripheral surface (outer peripheral surface on the opening side) of the outer peripheral protrusion 41C is a conical surface that is tapered so that the outer diameter dimension gradually decreases toward the other axial side (opening side).

A side portion 41D is formed on the outer periphery of the anchor 41, extending in a direction away from the opening of the storage cylinder portion 36A of the housing 36 along the outer periphery of the outer periphery protrusion 41C. The end of this side portion 41D away from the opening is an annular flange portion 41E that protrudes radially outward. The annular flange portion 41E is located at a position far away from the opening end of the storage cylinder portion 36A of the housing 36 to one side in the axial direction (i.e., the end opposite the recessed portion 41B).

The annular flange portion 41E is fixed, for example, by press-fitting into the fixing hole 39A of the yoke 39. The annular flange portion 41E is the fixing portion of the anchor 41 (side portion 41D) relative 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 flange portion 39D of the yoke 39 via a gap (radial gap).

As shown in FIG. 3, a second bushing 43 is fitted into a stepped through hole 41A formed on the center (inner circumference) side of the anchor 41 as a bearing (second bearing) for slidably supporting the operating pin 49. On the other hand, as shown in FIG. 2, the pilot body 26, return spring 28, disk valve 29, retaining plate 30, cap 31, etc. are inserted and provided on the inner circumference side of one side cylindrical portion 39G of the yoke 39. Also, the valve case 19 of the damping force adjustment valve 18 is fitted (outside) onto the outer circumference side of the one side cylindrical portion 39G.

The cylinder 44 is disposed between the yoke 39 and the anchor 41 in the radial direction. The cylinder 44 is also disposed between the yoke 39 and the housing 36 in 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 protrusion portion 39C of the yoke 39 and disposed on the inner periphery 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 cylinder (simple cylinder) from a non-magnetic material such as austenitic stainless steel.

The cylinder 44 is joined at the outer periphery of one end (yoke 39 side) in the winding axis direction of the molded coil 34 (coil 34A) to the inner periphery of the yoke 39 (fixing hole 39A, cylindrical protrusion 39C). As a result, the cylinder 44 is fixed to the yoke 39, whose one axial side serves as the stator. The cylinder 44 is joined at the inner periphery of the other end (housing 36 side) in the winding axis direction of the molded coil 34 (coil 34A) to the outer periphery of the housing 36 (small diameter cylindrical portion 36C). That is, the cylinder 44 is fitted (pressed) into the outside (outer periphery side) of the small diameter cylindrical portion 36C of the housing 36, and the two are joined by brazing.

The armature 48, also called a plunger, is disposed between the storage cylinder 36A of the housing 36 and the recessed portion 41B of the anchor 41. The armature 48 is a movable element (movable iron core) made of a magnetic material that is movable in the winding axis direction of the coil 34A. That is, the armature 48 is disposed on the inner periphery side of the coil 34A so as to be movable in the axial direction. The armature 48 is disposed on the inner periphery side of the storage cylinder 36A of the housing 36, the recessed portion 41B of the anchor 41, the cylindrical protrusion portion 39C of the yoke 39, and the cylinder 44, and is movable in the axial direction between the storage cylinder 36A of the housing 36 and the recessed portion 41B of the anchor 41. That is, the armature 48 is disposed on the inner periphery side of the storage cylinder 36A of the housing 36 and the recessed portion 41B of the anchor 41, and is movable in the axial direction via the first and second bushes 38, 43 and the operating pin 49 by the magnetic force generated in the coil 34A.

The armature 48 is fixed (integrated) to the actuation pin 49 that extends through the center of the armature 48, and moves together with the actuation pin 49. The actuation pin 49 is supported by the lid 36B of the housing 36 and the anchor 41 via the first and second bushes 38, 43 so that it can slide in the axial direction. Here, the armature 48 is formed in a substantially cylindrical shape using an iron-based magnetic material, for example, like the housing 36, the yoke 39, and the anchor 41. A thrust (attraction force) is generated in the armature 48 in a direction that attracts it toward the recessed portion 41B of the anchor 41 due to the magnetic force generated in the coil 34A.

The operating pin 49 is a shaft portion that transmits the thrust of the armature 48 to the pilot valve body 32, and is formed from a hollow rod. The operating pin 49 displaces integrally with the armature 48. That is, the armature 48 is fixed integrally to the axial middle portion of the operating pin 49 by means of press fitting or the like, and thus the armature 48 and the operating pin 49 are sub-assembled. Both axial sides of the operating pin 49 are slidably supported by the cover portion 36B on the housing 36 side and the yoke 39 (anchor 41) via the first and second bushes 38, 43.

One end of the operating pin 49 (the left end in FIG. 2, the lower end in FIG. 3) protrudes from the anchor 41 (yoke 39) in the axial direction, and the pilot valve body 32 of the damping force adjustment valve 18 is fixed to the protruding end. Therefore, the pilot valve body 32 moves axially together with the armature 48 and the operating 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 shock absorber 1 (i.e., the pilot valve body 32 relative to the pilot body 26).

The cover 51 is a magnetic cover that covers the molded coil 34 from the outside together with the other side tube portion 39H of the yoke 39. This cover 51 is formed of a magnetic material (magnetic body) 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 side tube portion 39H of the yoke 39, forms a magnetic circuit (magnetic path) outside the molded coil 34 (coil 34A). The cover 51 is formed into a covered cylinder shape as a whole, and is roughly composed of a cylindrical fitting tube portion 51A and a disk-shaped cover plate 51B that closes the other end side of the fitting tube portion 51A (the right end portion in FIG. 2, the upper end portion in FIG. 3).

Here, the fitting cylinder 51A of the cover 51 is inserted into the outer periphery of the lid 36B of the housing 36, and in this state, the lid 36B of the housing 36 is housed inside. Meanwhile, the lid plate 51B of the cover 51 has an annular flange 51C on its outer periphery that extends radially outward from the fitting cylinder 51A, and the outer diameter side of the flange 51C is fixed to a crimped portion 39J provided on the other cylinder 39H of the yoke 39. As a result, the other cylinder 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 in on the inside, as shown in FIG. 3.

In this way, when the molded coil 34 is built inside the other side cylinder 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 cylinder portion 51A of the cover 51. This allows magnetic flux to be transferred between the fitting cylinder portion 51A of the cover 51, the lid plate 51B, and the yoke 39. In addition, a seal groove 51D is formed around the entire circumference of the fitting cylinder portion 51A of the cover 51 on the outer periphery side 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 seal member. The O-ring 52 provides a liquid-tight seal between the molded coil 34 and the cover 51 (fitting cylinder portion 51A). This prevents dust, including rainwater and muddy water, from entering between the housing 36 and the molded coil 34 through the gap between the cover 51 and the molded coil 34, and even between the housing 36 and the cover 51.

As shown in FIG. 3, the yoke 39 and cover 51 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, as shown in FIG. 2, with the molded coil 34 built inside. In this case, the retaining ring 54 is attached to the engagement recess 39L of the yoke 39 prior to 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 of the lock nut 53 to one side cylindrical portion 39G of the yoke 39.

The lock nut 53 is formed as a stepped cylindrical body, and has a female threaded portion 53A located on one axial side thereof, which screws into the male threaded portion 19B of the valve case 19 on its inner periphery, and an engagement cylindrical portion 53B which 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 which integrally connects the damping force adjustment valve 18 and the solenoid 33 by screwing the female threaded portion 53A into the male threaded portion 19B of the valve case 19 with the inner surface of the engagement cylindrical portion 53B abutting against the retaining ring 54 attached to the engagement recess 39L of the yoke 39.

Now, let us consider the waterproofness 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, consider the case where the seal groove of the cover faces the boundary between the bobbin constituting the molded coil and the resin part (exterior resin). That is, consider the case where the periphery of the side wall on the movable element (armature) side of the pair of side walls (side walls facing each other in the axial direction) constituting the seal groove faces the bobbin. In this case, the O-ring fitted in the seal groove abuts against 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, this may lead to a decrease in the adhesion of the O-ring and damage due to contact between the O-ring and the step, which may lead to a decrease in waterproofness. And if waterproofness cannot be sufficiently ensured, it may lead to a short circuit due to, for example, water intrusion. Furthermore, if you try to shorten the axial length (dimension in the axial direction) of the solenoid while using an O-ring to waterproof the area between the cover and the resin part, the thickness of the bobbin and the resin part will become uneven. In this case, sink marks (distortion) may occur, which may worsen moldability.

Therefore, in the embodiment, the following configuration is adopted to achieve both "shortening the axial length of the solenoid 33" and "ensuring waterproofing by the O-ring 52". That is, in the embodiment, the axial length (axial dimension) of the solenoid 33 is shortened. In this case, as shown in FIG. 4, the cylindrical portion 34C1 of the resin portion 34C facing the seal groove 51D is extended toward the inner side (rear side, anchor 41 side) of the axial direction 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 portion 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 inner side (rear side, anchor 41 side) of the axial direction of the coil 34A. Both axial ends 51D1, 51D2 of the seal groove 51D face the resin portion 34C (cylindrical portion 34C1). In this embodiment, an annular protrusion 34B1 is formed on one axial end face (cover 51 side) of the bobbin 34B so as to ensure stable moldability of the resin portion 34C (cylindrical portion 34C1) and protrudes in the axial direction from this end face. A protrusion 34B2 is provided on the inner circumference of the bobbin 34B on the other axial side (anchor 41 side opposite the cover 51) of the O-ring 52. These points will be described in detail below.

First, as shown in FIG. 1, the shock absorber 1 includes an inner cylinder 4 and an outer cylinder 2 as cylinders, a piston 5, a piston rod 8, an annular oil chamber D (more specifically, a flow path between the annular oil chamber D and the reservoir chamber A) that serves as a flow path, and a damping force adjustment valve 18 (pilot valve body 32, and therefore the main valve 23). The damping force adjustment valve 18 (pilot valve body 32, and therefore the main valve 23) is provided in the flow path where the flow of the working fluid occurs due to the extension 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 therefore the main valve 23) is driven by a solenoid 33.

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 member, an anchor 41 as a stationary member, a resin section 34C, a cover 51, a seal groove 51D and an O-ring 52 as a seal member, and a damping force adjustment valve 18 as a control valve (more specifically, a pilot valve body 32, and thus a main valve 23). The damping force adjustment valve 18 (pilot valve body 32, and thus a main valve 23) is controlled by the axial movement of the armature 48 fixed to the actuation pin 49. As shown in FIG. 3, the solenoid 33 includes a coil 34A, a bobbin 34B, a housing 36, an armature 48, an anchor 41, a resin section 34C, a cover 51, a seal groove 51D and an O-ring 52. The solenoid 33 also includes a yoke 39.

The coil 34A is wound in a ring shape, and generates a magnetic force (magnetic flux, magnetic field) when electricity is applied. The coil 34A is wound around the bobbin 34B. The housing 36 is arranged on the inner circumference of the bobbin 34B. The housing 36 extends in the winding axis direction of the coil 34A, and one end side (the lower side in the vertical direction in FIG. 3) is open. The housing 36 accommodates the armature 48 and is provided radially between the coil 34A and the armature 48. The armature 48 is made of a magnetic material. The armature 48 is provided inside (inner diameter side) of the housing 36 so as to be movable in the winding axis direction of the coil 34A. The anchor 41 is provided on one side in the movement direction of the armature 48 (the lower side in the vertical direction in FIG. 3). That is, the anchor 41 is provided at a position facing the opening of the housing 36. The resin part 34C covers the bobbin 34B. The cover 51 covers the housing 36. The cover 51 forms a magnetic circuit. The seal groove 51D is provided in the cover 51. The O-ring 52 is fitted in the seal groove 51D. The anchor 41 is attached to the yoke 39.

The solenoid 33, together with the pilot valve body 32, constitutes a solenoid valve (pressure control valve). In the solenoid 33, a magnetic flux is generated by passing a current through the coil 34A, and the magnetic flux passes through a magnetic circuit formed by 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, and controls the opening and closing of the pilot valve body 32.

As shown in FIG. 4, in the embodiment, both axial ends of the seal groove 51D are formed in a position facing the resin portion 34C. That is, both axial ends 51D1, 51D2 of the seal groove 51D face the resin portion 34C (cylindrical portion 34C1). Here, of both axial ends 51D1, 51D2 of the seal groove 51D, the end (side wall) located on the side closer to the coil 34A (the anchor 41 side) is the inner end 51D1, and the end (side wall) located on the side farther from the coil 34A (the side away from the anchor 41) is 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 portion 34C (cylindrical portion 34C1), i.e., the joint K between the bobbin 34B located on the cover 51 side and the resin portion 34C (cylindrical portion 34C1), is positioned closer to the coil 34A (toward the anchor 41) than the inner end 51D1 of the seal groove 51D. This prevents the O-ring 52 attached to the seal groove 51D from abutting against the boundary K between the bobbin 34B and the resin portion 34C (cylindrical portion 34C1).

The boundary K between the bobbin 34B and the resin part 34C has the following configuration. That is, the inner diameter of the part of the bobbin 34B facing the fitting cylinder part 51A of the cover 51 and located closer to the coil 34A (anchor 41 side) than the seal groove 51D is "d". On the other hand, the inner diameter of the cylindrical part 34C1, which is the part of the resin part 34C facing the seal groove 51D, is "D". In this case, the inner diameter D of the resin part 34C (cylindrical part 34C1) is larger than the inner diameter d of the bobbin 34B. Therefore, the boundary K between the bobbin 34B and the resin part 34C has a step 61. Even if the boundary K has a step 61, the edge (inner peripheral edge) of this step 61 is located closer to the coil 34A (anchor 41 side) than the inner end 51D1 of the seal groove 51D. This prevents the O-ring 52 installed in the seal groove 51D from coming into contact with the edge (inner peripheral edge) of the step 61.

In addition, in the embodiment, an annular protrusion 34B1 is formed on one axial end (end on the cover 51 side) of the bobbin 34B. The annular protrusion 34B1 protrudes in the axial direction from the end face of the bobbin 34B on the cover 51 side toward the cover 51 side over the entire circumference. This makes it possible to suppress the occurrence of sink marks (warping) in the resin part 34C from the periphery of the annular protrusion 34B1 to the part extending along the fitting tube part 51A of the cover 51 (i.e., the cylindrical part 34C1). That is, if the boundary K between the bobbin 34B and the resin part 34C (cylindrical part 34C1) is to be provided on the inner side (anchor 41 side), the thickness of the resin part 34C (cylindrical part 34C1) may become uneven and sink marks (warping) may occur, but by providing the annular protrusion 34B1 and making the thickness constant, sink marks (warping) can be suppressed.

In the embodiment, the protrusion 34B2 having a circumferentially extending convex portion 34B3 and a concave portion 34B4 is provided on the inner circumference of the bobbin 34B, on the other axial end side (the anchor 41 side opposite the cover 51) of the O-ring 52. That is, as shown in FIG. 5, the inner circumference side of the bobbin 34B is provided with a protrusion 34B2 that extends in the circumferential direction and protrudes radially inward. In this case, the protrusion 34B2 has a convex portion 34B3 that protrudes radially inward and a concave portion 34B4 as a notch that is concave radially outward with respect to the inner circumference surface of the convex portion 34B3. In this case, the convex portion 34B3 is formed in a semicircular arc shape extending approximately 180 degrees at two positions in the circumferential direction of the protrusion 34B2. The concave portion 34B4 is provided between the convex portions 34B3. That is, the recesses 34B4 are provided at two or more positions (positions approximately equally spaced in the circumferential direction) on the protrusion 34B2. The protrusion 34B2 having such recesses 34B4 and protrusions 34B3 allows the bobbin 34B to be positioned when the resin portion 34C is molded, and the bobbin 34B can be stabilized within the mold.

The solenoid 33, damping force adjustment mechanism 17, and shock absorber 1 of this embodiment have the configuration described above, and their operation will be explained next.

First, when mounting the shock absorber 1 on 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) provided on the vehicle body via an electrical wiring cable (neither shown) or the like.

When the vehicle is traveling and vertical vibrations occur due to unevenness in the road surface, the piston rod 8 displaces from the outer cylinder 2 to expand or contract, and a damping force can be generated by the damping force adjustment mechanism 17, etc., to cushion the vehicle vibrations. At this time, the controller controls the current value to the coil 34A of the solenoid 33, and adjusts the opening pressure of the pilot valve body 32, thereby variably adjusting the damping force generated by the shock absorber 1.

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 connection tube 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 oil moved by the piston 5 opens the extension side check valve 16 of the bottom valve 13 from the reservoir chamber A and flows into the bottom side oil chamber C. When the pressure in the rod side oil chamber B reaches the opening pressure of the disc valve 6, the disc valve 6 opens, relieving the pressure in the rod side oil chamber B to the bottom side oil chamber C.

In the damping force adjustment mechanism 17, before the main valve 23 opens (low piston speed range), the oil that has flowed into the oil passage 20B of the connecting pipe body 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 the arrow X in Figure 2, pushing open the pilot valve body 32, and flows into the inside of the pilot body 26. Then, the oil that has flowed into the inside of the pilot body 26 flows between the flange portion 32A of the pilot valve body 32 and the disc valve 29, through 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, pushes open the main valve 23, and flows through the oil chamber 19C of the valve case 19 to the reservoir chamber A, as shown by the arrow Y in Figure 2.

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 check valve 7 of the piston 5, and the extension check valve 16 of the bottom valve 13 closes. Before the bottom valve 13 (disc valve 15) opens, the oil in the bottom oil chamber C flows into the rod oil chamber B. At the same time, the oil equivalent to the amount of oil that the piston rod 8 has penetrated into the inner cylinder 4 flows from the rod oil chamber B through the damping force adjustment valve 18 to the reservoir chamber A in the same route as during the extension stroke. When the pressure in the bottom 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 oil chamber C to the reservoir chamber A.

As a result, during the extension stroke and compression stroke of the piston rod 8, before the main valve 23 of the damping force control 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, and 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.

Specifically, when the current passing through the coil 34A is reduced to reduce the thrust of the armature 48, the opening pressure of the pilot valve body 32 decreases, and a soft damping force is generated. On the other hand, when the current passing through the coil 34A is increased to increase the thrust of the armature 48, the opening pressure of the pilot valve body 32 increases, and a hard damping force is generated. At this time, the internal pressure of the back pressure chamber 27, which communicates with the pilot valve body 32 via the upstream oil passage 25, changes depending on the opening pressure of the pilot valve body 32. As a result, by controlling the opening pressure of the pilot valve body 32, the opening pressure of the main valve 23 can be adjusted at the same time, and the adjustment range of the damping force characteristics can be widened.

If the thrust of the armature 48 is lost due to a break in the coil 34A or other reason, the pilot valve body 32 moves backward (displaced away from the valve seat portion 26E) due to the return spring 28, and the flange portion 32A of the pilot valve body 32 comes into contact with the disc valve 29. In this state, a damping force can be generated by the valve 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 break in the coil.

Here, according to the embodiment, the inner end 51D1 and the outer end 51D2, which are the axial ends of the seal groove 51D, are both formed at positions facing the resin part 34C (cylindrical part 34C1). Therefore, the O-ring 52 attached to the seal groove 51D can be abutted against the resin part 34C (cylindrical part 34C1). That is, the O-ring 52 attached to the seal groove 51D can be prevented from reaching the bobbin 34B. This can prevent the O-ring 52 from abutting against 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 adhesion with the resin part 34C (cylindrical part 34C1), and prevent damage to the O-ring 52, thereby improving the waterproofing by the O-ring 52.

According to the embodiment, an annular convex portion 34B1 is formed on the end (end face) on the cover 51 side, which is one end in the axial direction of the bobbin 34B. Therefore, even if the resin portion 34C (cylindrical portion 34C1) is extended toward the anchor 41 side along the axial direction of the bobbin 34B to face both the inner end 51D1 and the outer end 51D2 of the seal groove 51D to the resin portion 34C (cylindrical portion 34C1), it is possible to suppress the occurrence of sink marks (distortion) in the part, that is, the cylindrical portion 34C1, which is the part of the resin portion 34C that faces the seal groove 51D. That is, by forming the annular convex portion 34B1 on the end face on the cover 51 side of the bobbin 34B, the thickness can be made constant from the part of the resin portion 34C that covers the periphery of the annular convex portion 34B1 of the bobbin 34B to the part that faces the seal groove 51D (i.e., the cylindrical portion 34C1). This helps prevent sink marks (distortion) from occurring in the area (cylindrical portion 34C1) of resin portion 34C that faces seal groove 51D.

According to the embodiment, the protrusion 34B2 having a circumferentially extending convex portion 34B3 and a concave portion 34B4 is provided on the inner circumference of the bobbin 34B on the anchor 41 side, which is the other axial end side of the O-ring 52. This allows the bobbin 34B to be stabilized in the mold during molding. That is, the convex portion 34B3 of the protrusion 34B2 is sandwiched between the mold, thereby preventing the bobbin 34B from moving in the axial direction. In addition, the concave portion 34B4 of the protrusion 34B2 fits into a part of the mold, thereby preventing the bobbin 34B from moving in the circumferential direction (rotational direction). This allows the bobbin 34B to be stabilized in the mold, ensuring molding stability.

In the embodiment, an example was described in which the recessed portion 41B of the anchor 41 has a flat bottom surface, and the opposing portion of the armature 48 that faces the recessed portion 41B is also flat. However, this is not limited to the above, and for example, a configuration in which an intermediate protrusion that protrudes in a triangular cross section toward the armature is provided in the recessed portion of the anchor, and a groove portion with a triangular cross section is provided in the armature corresponding to the intermediate protrusion may be provided.

In the embodiment, the housing 36 and the cylinder 44, and the cylinder 44 and the yoke 39 are joined via brazing material. However, this is not limiting, and for example, the housing 36 and the cylinder 44, and the cylinder 44 and the yoke 39 may be joined by welding.

In the embodiment, the anchor 41 is fixed in the fixing hole 39A of the yoke 39 by press-fitting. However, this is not limited to the above, and the anchor may be fixed in the yoke using, for example, a screw or other threading means, a crimping means, or the like.

In the embodiment, the anchor 41 and the yoke 39 are configured as separate bodies (separate parts) as an example. However, this is not limiting, and for example, the anchor and the yoke may be configured as an integral part (one part).

In the embodiment, an example has been described in which one side of the cylinder 44 is fixed to the yoke 39. However, this is not limiting, and for example, one side of the cylinder (joint) may be fixed to the anchor.

In the embodiment, an example has been described in which the other-side tubular portion 39H is provided on the yoke 39, and the tip side (the other axial side) of the other-side tubular portion 39H is fixed to the outer periphery of the cover 51 by the crimping portion 39J. However, this is not limiting, and for example, the annular portion of the yoke and the other-side tubular portion may be formed separately, and the other-side tubular portion may be formed integrally with the cover portion.

In the embodiment, the solenoid 33 is configured as a proportional solenoid. However, this is not limiting, and the solenoid may be configured as, for example, an ON/OFF type solenoid.

In the embodiment, a twin-tube shock absorber 1 consisting of an outer tube 2 and an inner tube 4 has been described as an example. However, the present invention is not limited to this, and may be used, for example, in a damping force adjustable shock absorber consisting of a single-tube cylindrical member (cylinder).

In the embodiment, the solenoid 33 is used as a variable damping force actuator for the shock absorber 1, that is, the pilot valve body 32 constituting the pilot valve of the damping force adjustment valve 18 is used as the driven object of the solenoid 33. However, the present invention is not limited to this, and the solenoid can be widely used as an actuator incorporated in various mechanical devices such as valves used in hydraulic circuits, that is, a drive device that drives a driven object that should be driven linearly.

According to the embodiment described above, the axial ends of the seal groove are both formed at positions facing the resin portion. Therefore, the seal member attached to the seal groove can be abutted against the resin portion. That is, the seal member attached to the seal groove can be prevented from reaching the bobbin. This prevents the seal member from abutting against the boundary between the resin portion and the bobbin. This ensures the durability of the seal member, ensures adhesion with the resin portion, and prevents damage to the seal member, improving the waterproofing of the seal member.

According to the embodiment, an annular protrusion is formed at one end in the axial direction of the bobbin. Therefore, even if the resin part is extended along the axial direction of the bobbin so that both axial ends of the seal groove face the resin part, it is possible to suppress the occurrence of sink marks (distortion) in the part of the resin part facing the seal groove. In other words, by forming an annular protrusion at one end in the axial direction of the bobbin, it is possible to make the thickness of the resin part constant from the part that covers the periphery of the annular protrusion of the bobbin to the part that faces the seal groove. This makes it possible to suppress the occurrence of sink marks (distortion) in the resin part (the part that faces the seal groove).

According to the embodiment, a protrusion having a convex portion and a concave portion extending in the circumferential direction is provided on the inner circumference of the bobbin, closer to the other end in the axial direction than the sealing member. This allows the bobbin to be stabilized within the mold during molding. That is, the convex portion of the protrusion is sandwiched between the mold, thereby preventing the bobbin from moving in the axial direction. Furthermore, the concave portion of the protrusion fits into a part of the mold, thereby preventing the bobbin from moving in the circumferential direction (rotational direction). This allows the bobbin to be stabilized within the mold.

1. Shock absorber (damping force adjustable shock absorber)
2. External cylinder
4. Inner cylinder
5 Piston 8 Piston rod 17 Damping force adjustment mechanism 18 Damping force adjustment valve 32 Pilot valve body (control valve)
33 Solenoid 34A Coil 34B Bobbin 34B1 Annular convex portion 34B2 Projection portion 34B3 Convex portion 34B4 Concave portion 34C Resin portion 36 Housing (storage portion)
41 Anchor (stator)
48 Armature (moving element)
51 Cover 51D Seal groove 51D1 Inner end (axial end)
51D2 Outer end (axial end)
52 O-ring (sealing member)

Claims (3)

A solenoid comprising:
A coil that is wound in a circular shape and generates a magnetic force when electricity is passed through it;
a bobbin around which the coil is wound;
a storage section disposed on an inner periphery of the bobbin, extending in a direction of a winding axis of the coil and having an open end;
a mover provided in the storage section so as to be movable in a winding axis direction of the coil;
a stator provided at a position facing an opening of the storage portion;
A resin portion covering the bobbin;
A cover for covering the storage section;
a seal groove provided in the cover and a seal member attached to the seal groove;
having
A solenoid is formed such that both axial ends of the seal groove face the resin portion. The solenoid according to claim 1, wherein an annular protrusion is formed at one axial end of the bobbin. The solenoid according to claim 1, wherein a protrusion having a convex portion and a concave portion extending in the circumferential direction is provided on the inner circumference of the bobbin, closer to the other axial end side than the seal member.

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