Solenoid valve

Abstract

Provided is a solenoid valve capable of obtaining a thrust of a movable iron core in proportion to a current value applied to a coil.　This solenoid valve 1 comprises: a movable iron core 4; a solenoid formed body 31 disposed on the outer diameter side of the movable iron core 4 and having a coil 34; a solenoid case 30 in which the movable iron core 4 and the solenoid formed body 31 are accommodated; a fixed iron core 32 that is disposed on the inner diameter side of the solenoid formed body 31 and generates a magnetic force between the fixed iron core 32 and the movable iron core 4 via the electrification of the coil 34; and a valve part 2 that opens or closes a flow path by moving the movable iron core 4, wherein a magnetic material 8 separate from the solenoid case 30 is disposed at an axial end of the coil 34 outside the solenoid case 30.

Description

[Technical field]

[0001] The present invention relates to a solenoid valve used, for example, for hydraulic control in a hydraulic circuit. [Background technology]

[0002] A solenoid valve for hydraulic control includes a solenoid body having a coil, a fixed core which is a cylindrical stator, and a movable core which is a columnar plunger. The solenoid body is housed inside a solenoid case which is a yoke made of a magnetic material. The fixed core is disposed inside the solenoid body. The movable core is housed inside the stator. A solenoid valve is known in which a magnetic path is formed by the yoke, stator, and plunger when current is applied to the coil, generating a magnetic force between the stator and plunger, and moving the plunger axially inside the stator (see, for example, Patent Document 1).

[0003] In the manufacturing process, the solenoid case of such a solenoid valve is generally formed into a bottomed cylindrical shape by pressing a metal plate. By forming the cylindrical part and the bottom of the solenoid case so that they are continuous in this way, a magnetic path can be formed along the magnetic field that forms a closed curved surface with respect to the cylindrical part of the coil. Therefore, the stator and the plunger can be effectively magnetized with minimal loss. In addition, the coil of such a solenoid valve has a magnetic flux density that is proportional to the current value passed through it, and by adjusting the current value passed through the coil, a thrust force is obtained to move the plunger by the required stroke. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2015-137757 A (Page 5, Figure 1) Summary of the Invention [Problem to be solved by the invention]

[0005] The saturation magnetic flux density of the magnetic path is determined by the cross-sectional area, and in a solenoid valve such as that described in Patent Document 1, the bottom of the axial end of the coil on the plunger side in the solenoid case is formed in a thin plate shape. Also, the bottom has a shape in which the diameter becomes smaller and the cross-sectional area gradually decreases toward the inner diameter direction. As a result, the saturation magnetic flux density of the bottom gradually decreases toward the inner diameter direction. For this reason, when a large thrust is required for the plunger, if a high current is applied to the coil, the magnetic flux generated by the coil exceeds the saturation magnetic flux density of the magnetic path, and there is a problem that the applied current value and the thrust of the plunger are not proportional.

[0006] The present invention has been made in view of the above-mentioned problems, and has as its object to provide a solenoid valve which is capable of obtaining a thrust force from a movable iron core in proportion to the value of the current applied to the coil. [Means for solving the problem]

[0007] In order to solve the above problems, the solenoid valve of the present invention comprises: A movable core that is movable in the axial direction; a solenoid molded body having a coil and disposed on an outer diameter side of the movable iron core; a solenoid case that accommodates the movable core and the solenoid molded body; a fixed core disposed on an inner diameter side of the solenoid body and configured to generate a magnetic force between the fixed core and the movable core when a current is applied to the coil; a valve portion that opens and closes a flow path by movement of the movable core; A solenoid valve having A magnetic member separate from the solenoid case is disposed at an axial end of the coil outside the solenoid case. According to this, by disposing a magnetic material at the axial end of the coil on the movable core side outside a solenoid case having a bottom structure, for example, where the saturation magnetic flux density gradually decreases toward the inner diameter, the cross-sectional area of ​​the magnetic path at that location can be expanded. Since more magnetic flux is induced from the magnetic material to the movable core side, and the magnetic flux that increases according to the current value applied to the coil can be effectively used to magnetize the fixed core and the movable core, a thrust force of the movable core proportional to the current value can be obtained. In addition, by disposing a separate magnetic material outside the solenoid case, the magnetic flux density can be adjusted without changing the shape of the solenoid case by changing the magnetic material according to the maximum value of the current applied to the coil.

[0008] An axial end portion of the coil outside the solenoid case may be formed with an annular step portion recessed in an inward radial direction, and the magnetic material may be disposed within the annular step portion. This makes it possible to increase the cross-sectional area of ​​the magnetic path without forming unnecessary magnetic paths and while maintaining the compactness of the solenoid case.

[0009] The magnetic member may be disposed at a position where it always overlaps with the movable iron core in the radial direction. This allows magnetic flux to be effectively guided from one side to the other between the magnetic material and the movable core, suppressing magnetic loss and expanding the cross-sectional area of ​​the magnetic path.

[0010] The magnetic material may be in the form of a ring-shaped magnetic body. This makes it possible to form a magnetic path having a uniform magnetic flux density in the circumferential direction.

[0011] The magnetic material may be formed of a plurality of ring-shaped magnetic bodies. This makes it possible to adjust the cross-sectional area of ​​the magnetic path to be expanded by changing the number of magnetic bodies.

[0012] The magnetic body may be fitted onto the outside of a side plate that constitutes the annular step portion of the solenoid case. This allows the magnetic body to be aligned with the solenoid case and the movable iron core therein, forming a magnetic path having a uniform magnetic field strength in the circumferential direction.

[0013] The magnetic body may abut against an end plate that constitutes the annular stepped portion of the solenoid case. This allows the magnetic body to be positioned in the axial direction of the solenoid case, and allows the magnetic body to be disposed in a position suitable for inducing as much magnetic flux from the magnetic material toward the movable core. [Brief description of the drawings]

[0014] [Figure 1] FIG. 1 is a perspective view of a solenoid valve according to a first embodiment of the present invention. [Diagram 2] FIG. 2 is a partially cutaway cross-sectional view showing the structure of a solenoid valve in the first embodiment. [Diagram 3] 5 is a partially cutaway cross-sectional view showing a method of fastening the stator and the solenoid case by crimping using a crimping jig. FIG. [Figure 4] FIG. 4 is a perspective view showing a magnetic body attached to a solenoid case. [Diagram 5] 5 is a partially cutaway cross-sectional view that illustrates a magnetic flux generated in the coil when the plunger has moved to the farthest position toward the valve portion. FIG. [Figure 6] 11 is a partially cutaway cross-sectional view that illustrates a magnetic flux generated in the coil when the plunger has moved to the farthest position opposite the valve portion. FIG. [Figure 7] 1 is a partially cutaway cross-sectional view that illustrates a schematic diagram of magnetic flux when a current is applied to a coil when two magnetic bodies are attached. FIG. Example 1

[0015] A solenoid valve according to a first embodiment will be described with reference to Fig. 1 to Fig. 7. In the following description, the left side of Fig. 2 corresponds to the upper side of the solenoid valve, and the right side of Fig. 1 corresponds to the lower side of the solenoid valve.

[0016] The solenoid valve 1 is a spool-type solenoid valve, and is used in hydraulically controlled devices such as an automatic transmission of a vehicle. The solenoid valve 1 is mounted horizontally to a mounting member such as a valve housing (not shown).

[0017] As shown in Figures 1 and 2, solenoid valve 1 is configured by integrating valve section 2, which functions as a valve to adjust the flow rate of a fluid, with solenoid section 3, which functions as an electromagnetic actuator. This solenoid valve 1 adjusts the opening of the flow path on the discharge side. Note that Figure 2 shows the solenoid valve 1 in a fully open state with current flowing through coil 34 of solenoid molded body 31.

[0018] The valve section 2 is composed of a sleeve 21, a spool 22, a coil spring (not shown), and a retainer 23. The sleeve 21 has openings such as an input port and an output port (not shown) on its outer periphery, which are connected to flow paths provided in a valve housing (not shown). The spool 22 is liquid-tightly accommodated in a through hole 21a of the sleeve 21 and has a plurality of lands (not shown). The spring biases the spool 22 leftward in the axial direction. The retainer 23 is attached to the right side of the sleeve 21 in the axial direction and holds the spring. This configuration is well known as a spool valve, so a detailed description will be omitted. The sleeve 21, the spool 22, and the retainer 23 are made of materials such as aluminum, iron, stainless steel, and resin.

[0019] 2, the solenoid unit 3 is mainly composed of a solenoid case 30, a solenoid body 31, and a stator 32 serving as a fixed iron core. The solenoid case 30 is made of a magnetic metal material such as iron. The solenoid body 31 is housed in the solenoid case 30. The stator 32 is disposed inside the solenoid body 31.

[0020] The solenoid case 30 is formed into a bottomed tubular shape by pressing a metal plate, and is mainly composed of a cylindrical portion 30a and a bottomed cylindrical protrusion 30b. The cylindrical portion 30a covers the outer periphery of the solenoid molded body 31. The protrusion 30b protrudes axially leftward from the axial left side (i.e., the other axial end side) of the cylindrical portion 30a and is formed with a smaller diameter than the cylindrical portion 30a. The central axis of the cylindrical portion 30a and the central axis of the protrusion 30b are arranged to approximately coincide. The protrusion 30b is composed of a disk-shaped bottom plate 30m and a cylindrical side plate 30k. The side plate 30k is connected perpendicular to the bottom plate 30m and extends in the axial direction. At the left axial end of the cylindrical portion 30a, a radially recessed annular step 30c is formed by a side plate 30k and an annular end plate 30n that is perpendicular to the side plate 30k and continues to the cylindrical portion 30a, which extends radially outwardly perpendicular to the side plate 30k. During crimping and fixing, which will be described later, the end plate 30n of the annular step 30c functions as a step that receives an axial load.

[0021] The inside of the solenoid case 30 is composed of a first housing cylinder portion 30d and a second housing cylinder portion 30e. The first housing cylinder portion 30d is formed by the inner surface of the cylindrical portion 30a and houses the solenoid molding 31. The second housing cylinder portion 30e is formed by the inner surface of the protruding portion 30b on the axial left side of the first housing cylinder portion 30d, and is adapted to receive the axial left end of the cylindrical portion 32a of the stator 32. The above-mentioned end plate 30n is formed in the radial direction on the axial left side of the first housing cylinder portion 30d. That is, the end plate 30n of the annular step portion 30c of the solenoid case 30 is formed on the outer diameter side and on the axial left side of the cylindrical portion 32a of the stator 32 and the thin-walled portion 32b described later.

[0022] The solenoid case 30 has a claw portion 30g formed at one axial end. The claw portion 30g is configured to be thin-walled in a predetermined range from an opening end 30p (see FIG. 3) on the axial right side of the cylindrical portion 30a to the axial left. At the axial right end of the cylindrical portion 30a, an annular surface portion 30h is formed on the axial left side of the claw portion 30g, extending radially toward the inner diameter side. This annular surface portion 30h is connected perpendicularly to the inner surface of the first housing cylinder portion 30d on the inner diameter side.

[0023] As shown in Fig. 2, the stator 32 is configured in a flanged cylindrical shape composed of a cylindrical portion 32a and a flange portion 32c. The flange portion 32c extends radially from the axial right end of the cylindrical portion 32a. A through hole 32d capable of accommodating the plunger 4 and the rod 5 as a movable iron core is formed in the radial center of the cylindrical portion 32a. A holder 36 made of resin or the like is attached to the axial left open end of the cylindrical portion 32a. The axial left end face of the holder 36 attached to the axial left open end of the cylindrical portion 32a is slightly spaced from the bottom plate 30m of the protruding portion 30b of the solenoid case 30, forming a gap in the axial direction.

[0024] Further, a thin-walled portion 32b is provided on the cylindrical portion 32a of the stator 32. The thin-walled portion 32b is formed to have a thin plate thickness by recessing an approximately axial center of the outer circumferential surface toward the inner diameter side in the circumferential direction into an isosceles trapezoidal shape in cross section.

[0025] A recess 32e is provided in the flange portion 32c of the stator 32. The recess 32e is recessed axially leftward at the radial center of the end face on the right side of the axial direction. The mounting portion 21b of the sleeve 21 is inserted and fixed in the recess 32e. The outer circumferential edge of the end face on the right side of the axial direction of the flange portion 32c is chamfered.

[0026] Furthermore, the flange portion 32c of the stator 32 is fixed to the solenoid case 30. In detail, the solenoid case 30 is fixed to the flange portion 32c by crimping the claw portion 30g along the chamfered portion 32f (see FIG. 3) formed on the outer circumferential edge of the end face on the right side of the axial direction of the flange portion 32c while the outer circumferential edge of the end face on the left side of the axial direction of the flange portion 32c is abutted against the annular surface portion 30h formed on the inner diameter side of the right end face of the axial direction of the cylindrical portion 30a of the solenoid case 30. The method of crimping and fixing the stator 32 and the solenoid case 30 will be described in detail later.

[0027] As shown in FIG. 2, the solenoid molded body 31 is mainly composed of a bobbin 33 and a coil 34. The bobbin 33 is provided on the outer diameter side of the cylindrical portion 32a of the stator 32. The coil 34 is wound around the outer diameter side of the bobbin 33. The solenoid molded body 31 is formed by molding the bobbin 33 and the coil 34 with resin 35. A control current is supplied to the coil 34 from a connector of a connector portion 35a extending to the outside from an opening 30j provided on the radially lower side of the solenoid case 30. The bobbin 33 is made of an insulating material such as a highly rigid resin or ceramics, and is molded integrally with the stator 32.

[0028] 3, the stator 32 and the solenoid case 30 are fixed by crimping by inserting the protrusion 30b of the solenoid case 30 from above into the recess 60 provided in the striking block 6, and then striking the claw 30g of the solenoid case 30 with the striking rod 7 along the chamfered portion 32f formed on the outer periphery of the axially upper end face of the flange portion 32c of the stator 32. The recess 60 of the striking block 6 is configured to have approximately the same diameter as the protrusion 30b of the solenoid case 30, and is configured to have an axial depth greater than the amount of protrusion of the protrusion 30b of the solenoid case 30.

[0029] In this way, when the claw portion 30g of the solenoid case 30 is crimped to the flange portion 32c of the stator 32, the load acting in the axial direction is received by the end plate 30n of the annular step portion 30c provided on the other axial end side of the solenoid case 30 and on the outer diameter side of the cylindrical portion 32a (thin portion 32b) of the stator 32, so that the axial load is less likely to be applied to the thin portion 32b of the stator 32 inside the solenoid case 30. Therefore, the plate thickness of the thin portion 32b of the stator 32 can be made thinner.

[0030] Furthermore, by making the plate thickness of the thin portion 32b of the stator 32 extremely thin, the magnetic resistance in the thin portion 32b of the stator 32 becomes larger when a magnetic path is formed by energizing the coil 34 while the solenoid valve 1 is in the on state. Therefore, the magnetic flux around the thin portion 32b can be biased toward the plunger 4, thereby increasing the magnetic force acting on the plunger 4.

[0031] 2, the left axial end of the cylindrical portion 32a of the stator 32 is fitted into the second housing cylinder portion 30e formed inside the protruding portion 30b protruding leftward in the axial direction on the inner diameter side of the annular step portion 30c formed at the left axial end of the solenoid case 30, so that the left axial end of the cylindrical portion 32a of the stator 32 can be disposed adjacent to and in contact with the side plate 30k of the protruding portion 30b of the solenoid case 30 in the radial direction. Therefore, between the annular step portion 30c of the solenoid case 30 and the left axial end of the cylindrical portion 32a of the stator 32, a magnetic flux with reduced magnetic resistance is secured, and the magnetic force acting on the plunger 4 is further increased.

[0032] In addition, by making the cylindrical portion 32a of the stator 32 long enough so that the axial left end of the cylindrical portion 32a of the stator 32 can be housed in the second housing cylinder portion 30e formed inside the protruding portion 30b of the solenoid case 30, the circle of magnetic flux on the outer periphery of the coil 34 can be enlarged. As a result, a strong magnetic force can be exerted on the plunger 4.

[0033] Next, the magnetic body 8 attached to the solenoid case 30 will be described. As shown in Fig. 2 and Fig. 4, the magnetic body 8 is formed in a ring shape with a uniform thickness and a through hole 8a in the center. The magnetic body 8 is formed of a metal or alloy mainly containing a magnetic material such as iron. The magnetic body 8 is formed so that the inner diameter of the through hole 8a is slightly smaller than the outer diameter of the cylindrical side plate 30k that constitutes the protruding portion 30b of the solenoid case 30, and is press-fitted and fixed into the cylindrical side plate 30k.

[0034] The magnetic body 8 is press-fitted until either the front or back surface 8b comes into contact with the outer surface of the annular end plate 30n (i.e., the large-diameter surface at the base of the protrusion 30b). This makes it easier to induce magnetic flux from the end plate 30n to the magnetic body 8.

[0035] Moreover, the outer diameter dimension of the outer peripheral surface 8c of the magnetic body 8 is approximately the same as the outer diameter dimension of the cylindrical portion 30a of the solenoid case 30. In other words, the magnetic body 8 is disposed so as to be contained within the annular step portion 30c. This allows the solenoid valve 1 to be configured compactly.

[0036] Moreover, the magnetic body 8 is disposed at an axial end of the coil 34. In particular, from the viewpoint of inducing magnetic flux, it is preferable that at least a part of the magnetic body 8 is disposed at an axial end of the winding portion of the coil 34. Moreover, it goes without saying that the axial end of the coil 34 includes the vicinity of the axial end of the coil 34.

[0037] Moreover, the magnetic body 8 is disposed at a position where it always overlaps with the plunger 4 in the radial direction, regardless of whether the plunger 4 is energized or not.

[0038] The magnetic flux generated by the coil 34 passes through the valve section 2 side of the cylindrical section 32a of the stator 32, the flange section 32c, the cylindrical section 30a of the solenoid case 30, the end plate 30n, the magnetic body 8, a part of the cylindrical side plate 30k, the side opposite the valve section 2 of the cylindrical section 32a of the stator 32, and the plunger 4. Note that the cross-sectional area of ​​the thin-walled section 32b of the stator 32 is extremely small, so almost no magnetic flux passes through it. This creates opposite magnetic poles in the opposing portion between the plunger 4 and the valve section 2 side of the stator 32, and the magnetic attraction between these generates a thrust force on the plunger 4, causing the plunger 4 to move towards the valve section 2 side.

[0039] If the magnetic body 8 is not attached to the protruding portion 30b, the end plate 30n of the solenoid case 30 is thin, and the cross-sectional area of ​​the magnetic path becomes smaller toward the inner diameter direction from the continuous portion between the end plate 30n and the cylindrical side plate 30k, i.e., the bent portion formed by pressing, and the saturated magnetic flux density gradually decreases. In other words, when a high current is applied to the coil 34 in an environment where a large thrust is required for the plunger 4, a sufficient magnetic flux cannot be secured at the portion. Therefore, if the saturated magnetic flux density is exceeded at the portion, the magnetic flux density of the magnetic path that magnetically attracts the plunger 4 and the valve portion 2 side of the stator 32, i.e., the thrust that moves the plunger 4 to the valve portion 2 side of the stator 32, becomes smaller than the applied current value. In other words, the applied current value and the thrust of the plunger 4 are not proportional, and there are cases where the thrust required to move the plunger 4 to accurately adjust the flow rate controlled by the valve portion 2 side cannot be secured.

[0040] In the solenoid valve 1 of this embodiment, the magnetic body 8 is mounted within the annular step portion 30c. Either the front or rear surface 8b of the magnetic body 8 is in contact with the outer surface of the end plate 30n of the solenoid case 30, and the inner peripheral surface of the through hole 8a of the magnetic body 8 is in contact with the outer peripheral surface of the cylindrical side plate 30k of the solenoid case 30, but a protective coating film (not shown) is formed on the outer surfaces of the solenoid case 30 and the magnetic body 8, and although the ferromagnetic materials that make up the two are not in direct contact with each other, they are in extremely close proximity due to the contact between the members, and the loss of magnetic field strength when the ferromagnetic materials are separated from each other is extremely small.

[0041] 5 shows the moment when a high current is applied to the coil 34 and the plunger 4 moves furthest toward the valve section 2, and diagrammatically illustrates the magnetic field lines (i.e., magnetic flux) generated in the coil 34 when a current is applied in this state. As shown in Fig. 5, the magnetic flux generated by the coil 34 passes through a magnetic path consisting of the valve section 2 side of the cylindrical section 32a of the stator 32, the flange section 32c, the cylindrical section 30a of the solenoid case 30, the end plate 30n, the magnetic body 8, part of the cylindrical side plate 30k, the side of the cylindrical section 32a of the stator 32 opposite the valve section 2, and the plunger 4.

[0042] At the end plate 30n of the solenoid case 30 and the continuous portion between the end plate 30n and the cylindrical side plate 30k, i.e., the bent portion formed by pressing, the magnetic body 8 is disposed overlapping the end plate 30n and abutting the cylindrical side plate 30k. When the magnetic body 8 is disposed at the position, the cross-sectional area constituting the magnetic path at the position is expanded and the saturation magnetic flux density is higher than when the magnetic body 8 is not attached. In other words, even when a high current value is applied to the coil 34, particularly in an environment where a large thrust is required to move the plunger 4 toward the valve portion 2 of the stator 32, a sufficient magnetic flux proportional to the current value can be secured at the position for the magnetic flux generated by the coil 34, and a thrust force sufficient to move the plunger 4 for the applied current can be obtained.

[0043] In addition, in the past, in an environment where a large thrust is required to move the plunger toward the valve portion of the stator, it is common to reduce the load of the spring that biases the spool 22 axially leftward. However, in this case, the effect of reducing the load of the spring is also present in the case of a low current value, making it difficult to perform fine adjustment of the opening according to the current value. In contrast, in this embodiment, the magnetic body 8 is arranged to increase the saturation magnetic flux density of the magnetic path, and a magnetic field strength proportional to a high current value is obtained, so that the magnetic field strength can be finely adjusted according to the current value. In other words, it is possible to ensure the thrust required to move the plunger 4 in order to accurately adjust the flow rate controlled by the valve portion 2.

[0044] Although not shown here, the magnetic field generated in the coil 34 by energization forms a closed curved surface with respect to the cylindrical coil 34. A magnetic body 8 having a ferromagnetic material is disposed near the axial end of the coil 34 opposite the valve section 2 side, and forms a magnetic path along the closed curved surface of the magnetic field generated in the coil 34 together with the solenoid case 30, the plunger 4, and the stator 32. As a result, the cross-sectional integral and saturation magnetic flux density of the magnetic body 8 are increased, particularly in the end plate 30n and side plate 30k on the bottom side of the solenoid case 30, which are thin.

[0045] Furthermore, since the magnetic body 8 is formed in a ring shape, it is possible to form a magnetic path having a uniform magnetic flux density in the circumferential direction.

[0046] Furthermore, the magnetic body 8 is disposed within annular step portion 30c formed on the opposite side of the solenoid case 30 from the valve portion 2, and is located on the inside of the outer diameter dimension and on the inside of the axial dimension of the solenoid case 30, so that the cross-sectional area of ​​the magnetic path can be expanded without forming unnecessary magnetic paths while maintaining the compactness of the solenoid case 30.

[0047] Moreover, in the stroke range from the state where the plunger 4 is located furthest on the valve section 2 side as shown in Fig. 6 to the state where the plunger 4 is located furthest on the opposite side to the valve section 2 (i.e., the bottom side of the solenoid case 30) as shown in Fig. 5, the magnetic body 8 is disposed in a position where it always overlaps with the radially outer side of the plunger 4. This makes it possible to effectively guide magnetic flux from one side to the other between the magnetic body 8 and the plunger 4, suppressing magnetic force loss and ensuring the magnetic flux density of the magnetic path.

[0048] The magnetic body 8 is fitted onto the outer peripheral surface of a cylindrical side plate 30k that constitutes the annular step portion 30c of the solenoid case 30. This allows the magnetic body 8, the solenoid case 30, and the plunger 4 inside to be axially aligned, forming a magnetic path with uniform magnetic field strength in the circumferential direction.

[0049] Furthermore, since either the front or back surface 8b of the magnetic body 8 is abutted against the outer surface of the end plate 30n that constitutes the annular step portion 30c of the solenoid case 30, the magnetic body 8 can be positioned in the axial direction of the solenoid case 30, and the magnetic body 8 can be reliably placed in a position that is suitable for obtaining the required magnetic field strength.

[0050] In addition, in FIG. 7, two magnetic bodies 8 are attached in the annular step portion 30c. According to this, in the end plate 30n of the solenoid case 30 in which the cross-sectional area constituting the magnetic path is gradually reduced, the cross-sectional area of ​​the magnetic path at that location is expanded by the thickness of two magnetic bodies 8, 8. Therefore, even when a higher current value is applied, more magnetic flux can be induced from the magnetic bodies 8, 8 to the plunger 4 side, and a thrust force of the plunger 4 proportional to the applied current value can be obtained. In other words, by adjusting the number of magnetic bodies 8 attached in the annular step portion 30c according to the maximum value of the applied current value, a thrust force of the plunger 4 proportional to the current value can be obtained.

[0051] As described above, by providing a separate magnetic body 8 outside the solenoid case 30, the magnetic flux density can be adjusted by changing the magnetic material according to the maximum value of the current applied to the coil 34, without changing the shape of the solenoid case 30. Note that instead of adjusting the number of identical magnetic bodies 8, it is also possible to adjust the magnetic flux density by preparing a plurality of magnetic bodies with different thicknesses and replacing them.

[0052] Although the embodiments of the present invention have been described above with reference to the drawings, the specific configuration is not limited to these embodiments, and the present invention also includes modifications and additions that do not deviate from the gist of the present invention.

[0053] For example, the stator 32 in the above embodiment is configured such that its flange portion 32c and cylindrical portion 32a are connected to the valve portion 2 side and the side opposite the valve portion 2 via the thin-walled portion 32b and are located on the outer diameter side of the plunger 4, but the present invention is not limited to this. For example, the stator, which is a fixed core, may be configured to be located only on the valve portion 2 side in the axial direction of the plunger.

[0054] Also, the magnetic body 8 may be configured not to be fitted onto the cylindrical side plate 30k constituting the annular step portion 30c, but to be fixed inside the annular step portion 30c with an adhesive or the like. Similarly, the magnetic body 8 may be configured to be fixed inside the annular step portion 30c with an adhesive or the like in a state separated from the end plate 30n constituting the annular step portion 30c.

[0055] Also, the magnetic body 8 may be configured to be fixed inside the annular step portion 30c with an adhesive or the like, without being fitted onto the cylindrical side plate 30k constituting the annular step portion 30c. Similarly, the magnetic body 8 may be configured to be fixed inside the annular step portion 30c with an adhesive or the like, without being in contact with the end plate 30n constituting the annular step portion 30c.

[0056] Furthermore, the outer diameter of the outer circumferential surface 8c of the magnetic body 8 may be smaller than the outer diameter of the cylindrical portion 30a of the solenoid case 30.

[0057] The cross-sectional shape of the magnetic body 8 is not limited to a rectangular shape as in the above embodiment, but is preferably a shape in which the cross-sectional area through which the magnetic flux passes does not decrease toward the inner diameter. Also, a right-angled triangular or trapezoidal cross section in which the surface facing the end plate 30n is perpendicular to the axial direction is preferable because there is no magnetic loss.

[0058] In the above embodiment, the solenoid case 30 has been described as having a bottomed shape in which the bottom plate 30m is disk-shaped, but the solenoid case 30 may have a bottomed shape in which a through hole is provided in the axial direction in the bottom plate.

[0059] In addition, in the above embodiment, the magnetic body 8 is formed by making the magnetic material into a ring shape, but this configuration is not limited to this. For example, the magnetic body 8 may be molded into a ring shape using a resin containing a magnetic material and pressed into the annular step portion 30c of the solenoid case 30.

[0060] In the above embodiment, a spool-type solenoid valve using a spool as a valve element has been described, but the present invention is not limited to this, and a solenoid valve using a globe valve, a gate valve, or the like may also be used. [Explanation of symbols]

[0061] 1 Solenoid valve 2 Valve section 3 Solenoid section 4 Plunger (movable core) 5 Rod 8 Magnetic material (magnetic material) 8a through hole 8b side 8c Outer surface 21 Sleeve 22 Spool 23 Retainer 30 Solenoid case 30a Cylindrical part 30b Convex part 30c Annular step (step) 30d First housing cylinder 30e Second housing cylinder 30f Annular surface part 30k side plate 30n end plate 31 Solenoid molding 32 Stator (fixed core) 32a Cylindrical part 32b Thin wall part 32c Flange part 33 Bobbin 34 Coil

Claims

1. a movable core that is movable in an axial direction; a solenoid molded body having a coil and disposed on an outer diameter side of the movable iron core; a solenoid case that accommodates the movable core and the solenoid molded body; a fixed core disposed on an inner diameter side of the solenoid body and configured to generate a magnetic force between the fixed core and the movable core when a current is applied to the coil; a valve portion that opens and closes a flow path by movement of the movable core; A solenoid valve having A solenoid valve, wherein a magnetic material separate from the solenoid case is press-fitted and fixed to the outside of the solenoid case and to an axial end of the solenoid case on the movable core side.

2. 2. The solenoid valve according to claim 1, wherein an annular step recessed in an inward radial direction is formed at an axial end of said coil outside said solenoid case, and said magnetic material is disposed within said annular step.

3. 3. The solenoid valve according to claim 2, wherein the magnetic member is disposed at a position where it always overlaps with the movable iron core in the radial direction.

4. 4. The solenoid valve according to claim 2, wherein the magnetic member is formed into a ring-shaped magnetic body.

5. 4. The solenoid valve according to claim 2, wherein the magnetic member is formed of a plurality of ring-shaped magnetic bodies.

6. 6. The solenoid valve according to claim 4, wherein the magnetic body is fitted onto an outer surface of a side plate that constitutes the annular step portion of the solenoid case.

7. 7. The solenoid valve according to claim 4, wherein the magnetic body is in contact with an end plate that constitutes the annular stepped portion of the solenoid case.

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