Solenoid valve and manufacturing method therefor

Abstract

This solenoid valve comprises: a rod (15) which has a valve body (34) at one end and in which at least the other end thereof is formed from an elastic resin material having elasticity; a plunger (16) into which said other end of the rod (15) is inserted and which moves, by means of electromagnetic force, in the valve-opening direction of the valve body (34); and a yoke (17) which is provided at the position toward which the plunger (16) moves when moving in the valve-opening direction. When the valve body (34) is open, there is a gap between said other end of the rod (15) and the yoke (17).

Description

Solenoid valve and method of manufacturing the same

[0001] The present disclosure relates to a solenoid valve and a method for manufacturing the solenoid valve.

[0002] Patent Document 1 discloses a solenoid valve that closes by the biasing force of a biasing means such as a spring and opens by electromagnetic force generated by energizing a solenoid coil.

[0003] JP 2009-293713 A

[0004] The solenoid valve disclosed in Patent Document 1 has a valve body at one end of a plunger and a buffer member at the other end of the plunger. The plunger moves in the valve-opening direction due to electromagnetic force generated by energizing a solenoid coil. The buffer member at the other end of the plunger abuts against a fixed magnetic pole, restricting the plunger's movement in the valve-opening direction. The solenoid valve disclosed in Patent Document 1 suppresses the impact noise of the plunger when the valve is opened by providing the buffer member to the plunger.

[0005] The buffer member disclosed in Patent Document 1 is made of an elastic resin material. Therefore, the size or shape of the buffer member changes over time due to frequency of use, moisture absorption, oil absorption, and the like. When the volume of the buffer member changes, the solenoid valve disclosed in Patent Document 1 opens by utilizing the impact of the buffer member, resulting in an unstable valve opening. As a result, the solenoid valve disclosed in Patent Document 1 may not allow fluid to flow at an appropriate flow rate when the valve is open.

[0006] The present disclosure has been made to solve the above-mentioned problems, and aims to provide an electromagnetic valve that can suppress changes in the valve opening degree when the valve is open, even if volume fluctuations occur in the buffer member.

[0007] The solenoid valve of the present disclosure comprises a rod having a valve body at one end and at least the other end formed of an elastic resin material having elasticity, a plunger into which the other end of the rod is inserted and which moves in the valve opening direction of the valve body by electromagnetic force, and a yoke provided at the end of the plunger moving in the valve opening direction, and when the valve body is open, there is a gap between the other end of the rod and the yoke.

[0008] According to the present disclosure, even if a volume change occurs in the buffer member, a change in the valve opening degree when the valve is opened can be suppressed.

[0009] Fig. 5 is a longitudinal sectional view of the solenoid valve according to embodiment 1 when the valve is open (when not energized). Fig. 6 is an enlarged view of the solenoid portion in Fig. 1. Fig. 7 is a longitudinal sectional view of the solenoid valve according to embodiment 1 when the valve is closed (when energized). Fig. 8 is an enlarged view of the solenoid portion in Fig. 3. Fig. 9 is a longitudinal sectional view of the solenoid valve according to embodiment 1 when a valve opening transient response occurs (when not energized). Fig. 10 is an enlarged view of the solenoid portion in Fig. 5. Fig. 11 is a diagram illustrating the amount of gap between the rod and the yoke when the valve is open.

[0010] In order to explain the present disclosure in more detail, embodiments of the present disclosure will be described below with reference to the accompanying drawings.

[0011] First Embodiment A solenoid valve according to a first embodiment will be described with reference to FIGS.

[0012] First, the configuration of the solenoid valve according to the first embodiment will be described with reference to Figures 1 and 2. Figure 1 is a vertical cross-sectional view of the solenoid valve according to the first embodiment when the valve is open (when not energized). Figure 2 is an enlarged view of a main part of the solenoid unit 10 in Figure 1.

[0013] The solenoid valve according to the first embodiment shown in Fig. 1 opens by the biasing force of a biasing means such as a spring, and closes by electromagnetic force generated by energizing a solenoid coil 13. As shown in Fig. 1, the solenoid valve according to the first embodiment includes a solenoid unit 10 and a valve unit 30. The solenoid unit 10 is disposed on one axial side of the solenoid valve. The valve unit 30 is disposed on the other axial side of the solenoid valve. The solenoid unit 10 and the valve unit 30 are fixed to each other in the axial direction of the solenoid valve.

[0014] The solenoid unit 10 includes a housing 11, a bobbin 12, a solenoid coil 13, a guide core 14, a rod 15, a plunger 16, a yoke 17, a coil spring 18, a buffer member 19, and an air gap 21. The bobbin 12, the guide core 14, the rod 15, the plunger 16, and the buffer member 19 are arranged coaxially.

[0015] The housing 11 is fixed to a housing 31 of the valve unit 30, which will be described later. The housing 11 has a through hole 11a that communicates with the interior of the housing 31. The through hole 11a is formed at one end of the housing 11.

[0016] The bobbin 12 is provided in the housing 11. The bobbin 12 has a cylindrical shape. The solenoid coil 13 is wound around the outer periphery of the bobbin 12.

[0017] The guide core 14 has a cylindrical shape. The guide core 14 is inserted into the bobbin 12 from one end thereof to fit therewith, and is fixed to one end of the housing 11. One end of the guide core 14 protrudes from one end of the bobbin 12. Therefore, one end of the guide core 14 passes through the through-hole 11a of the housing 11 and enters the inside of the housing 31 of the valve portion 30.

[0018] The rod 15 is inserted into the bobbin 12. The rod 15 inserted into the bobbin 12 is further inserted into the guide core 14. At this time, one end of the rod 15 protrudes from one end of the guide core 14. In other words, one end of the rod 15 is exposed inside the housing 31. Furthermore, by being inserted into the guide core 14, the rod 15 is supported so as to be movable in the axial direction of the rod 15 relative to the guide core 14. The rod 15 is used to open, close, or move a valve element 34, which will be described later.

[0019] At least the other end of the rod 15 is formed from an elastic resin material having elasticity. Suitable elastic resin materials include rubber and thermoplastic elastomer. In this way, in the solenoid valve according to embodiment 1, by forming at least the other end of the rod 15 from an elastic resin material, even if the rod 15 moves more than necessary and collides with the yoke 17 (described later) when the valve is opened, damage to the yoke 17 and collision noise can be suppressed. In other words, the rod 15 is a member for opening and closing the valve element 34 (described later) and also a buffer member.

[0020] Although a buffer member made of an elastic resin material having elasticity is integrally formed on rod 15, rod 15 and the buffer member may be separate bodies. For example, in the solenoid valve according to embodiment 1, a separate buffer member made of an elastic resin material may be connected to the tip (other end) of rod 15 made of a metal material or an elastic resin material.

[0021] The plunger 16 is cylindrical. The plunger 16 is inserted into the bobbin 12. The plunger 16 is supported on the bobbin 12 so as to be movable in the axial direction of the plunger 16. The plunger 16 is made of, for example, a magnetic metal material. Therefore, when the solenoid coil 13 is energized, the plunger 16 generates an electromagnetic force on a yoke 17 (described later) due to the magnetic flux. As a result, the plunger 16 repels the yoke 17 and moves toward one end of the bobbin 12, i.e., toward the valve portion 30.

[0022] The other end of the rod 15 is inserted into the plunger 16. Therefore, the rod 15 moves integrally with the plunger 16. When inserting the rod 15 into the plunger 16, the rod 15 is press-fitted into the plunger 16 using a press-fitting jig or the like. Therefore, the rod 15 and the plunger 16 are arranged coaxially with high precision. As a result, the rod 15 and the plunger 16 can move integrally in a well-balanced manner, thereby stabilizing the valve-opening and valve-closing operations. Furthermore, by press-fitting the rod 15 into the plunger 16, the rod 15 and the plunger 16 can be supplied at once as a single component during assembly of the solenoid valve. This improves the efficiency of the assembly work of the solenoid valve.

[0023] As will be described in detail later, the plunger 16 moves in a valve-closing direction, which is a direction toward the valve portion 30, due to electromagnetic force generated by energizing the solenoid coil 13. When energization to the solenoid coil 13 is stopped, the plunger 16 moves in a valve-opening direction, which is a direction away from the valve portion 30.

[0024] The plunger 16 has a central hole into which the rod 15 fits, a storage hole 16a that stores a coil spring 18 (described later), and a mounting seat surface 16b. The central hole and storage hole 16a are arranged coaxially. The storage hole 16a is a hole that opens to the other end of the plunger 16. The diameter of the storage hole 16a is larger than the diameter of the central hole. The mounting seat surface 16b is a step surface between the fitting hole and storage hole 16a, which have different diameters.

[0025] As described above, the rod 15 is further inserted into the guide core 14 and plunger 16 that are inserted inside the bobbin 12, and an air gap 21 is provided between the guide core 14 that is fixed inside the bobbin 12 and the plunger 16 that is movably supported inside the bobbin 12. In this case, in the solenoid valve according to embodiment 1, the axial length of the air gap 21 is set to a predetermined length or longer. Therefore, the solenoid valve according to embodiment 1 prevents the plunger 16 from colliding with the guide core 14 even when the plunger 16 moves in the axial direction.

[0026] Furthermore, when only the rod 15 is made of an elastic resin material, or when the rod 15 and the buffer member are made of the same elastic resin material and integrated with each other, the method for manufacturing the solenoid valve according to embodiment 1 may involve manufacturing them by insert molding using the plunger 16 as an insert part. Specifically, the method for manufacturing the solenoid valve according to embodiment 1 involves setting the plunger 16, which has been formed in advance from a metal material, in a molding die (not shown), and then injecting an elastic resin material into the molding die to mold only the rod 15 or an integrated part of the rod 15 and the buffer member.

[0027] Therefore, the solenoid valve according to the first embodiment can arrange the rod 15 and the plunger 16 coaxially with high precision. Alternatively, the solenoid valve according to the first embodiment can arrange the rod 15, the buffer member, and the plunger 16 coaxially with high precision.

[0028] As a result, the rod 15 and plunger 16, or the rod 15, the buffer member, and the plunger 16, can move together in a well-balanced manner, stabilizing the valve opening and closing operations. Furthermore, by insert-molding these components, they can be supplied as a single component at once during assembly of the solenoid valve. This improves the efficiency of the solenoid valve assembly work.

[0029] The yoke 17 is provided so as to cover the open end on the other end side of the bobbin 12. The yoke 17 has a mounting seat surface 17a. The mounting seat surface 17a is disposed so as to face the open end on the other end side of the bobbin 12. The yoke 17 is formed of, for example, a magnetic metal material.

[0030] The coil spring 18 is interposed between the mounting seat surface 16b of the plunger 16 and the mounting seat surface 17a of the yoke 17. That is, one end of the coil spring 18 is attached to the mounting seat surface 16b, and the other end of the coil spring 18 is attached to the mounting seat surface 17a. The coil spring 18 is also disposed in the housing hole 16a of the plunger 16. The coil spring 18 is configured so that its length gradually extends as the plunger 16 moves in the valve-closing direction.

[0031] The other end of the rod 15 is inserted inside the coil spring 18. That is, the inner diameter of the coil spring 18 is larger than the outer diameter of the rod 15. For example, the inner diameter of the coil spring 18 is larger than the outer diameter of the rod 15 by about 1 mm. Furthermore, a gap having a predetermined length in the axial direction is provided between the other end of the rod 15 inserted into the coil spring 18 and the mounting seat surface 17a of the yoke 17 when the solenoid coil 13 is not energized, i.e., when the valve is open.

[0032] The buffer member 19 has an annular shape. The buffer member 19 is attached to the mounting seat surface 17a of the yoke 17. In this case, the buffer member 19 is disposed radially outward of the coil spring 18 attached to the mounting seat surface 17a. In other words, the inner diameter of the buffer member 19 is larger than the outer diameter of the coil spring 18. For example, the inner diameter of the buffer member 19 is larger than the outer diameter of the coil spring 18 by about 1 mm.

[0033] The buffer member 19 has an annular lip portion 19a. The lip portion 19a is provided so as to fit along the inner circumferential surface of the buffer member 19. The lip portion 19a is also provided so as to protrude from the buffer member 19 toward the plunger 16. Therefore, the tip of the lip portion 19a can come into contact with the open end of the housing hole 16a in the plunger 16 when the valve is open. As a result, the lip portion 19a can prevent foreign matter such as dust and dirt and fluid from entering the housing hole 16a of the plunger 16.

[0034] The buffer member 19 is formed, for example, from an elastic resin material having elasticity. Rubber or a thermoplastic elastomer is suitable as the elastic resin material. By using a thermoplastic elastomer as the elastic resin material forming the buffer member 19, the buffer member 19 can be easily molded.

[0035] The valve portion 30 includes a housing 31 , a flow path 32 , a valve seat 33 , a valve body 34 , and a coil spring 35 .

[0036] As described above, the housing 31 is fixed to the housing 11 of the solenoid unit 10. The flow path 32 is provided inside the housing 31. A fluid whose flow rate is controlled by the solenoid valve according to the first embodiment passes through this flow path 32. The arrow F shown in FIG. 1 indicates the direction of the fluid flow. In addition, a valve seat 33 is provided in the flow path 32.

[0037] The valve element 34 is disposed inside the housing 31 so as to face the valve seat 33. The valve element 34 is capable of being seated on the valve seat 33. The coil spring 35 is interposed between the outer periphery of the valve element 34 and the outer periphery of the valve seat 33 in the housing 31. The coil spring 35 biases the valve element 34 in the valve opening direction. Therefore, the back surface of the valve element 34 abuts against one end of the rod 15 exposed inside the housing 31. That is, the coil spring 35 biases the rod 15 together with the valve element 34 in the valve opening direction. Therefore, the valve element 34 moves in the axial direction together with the rod 15.

[0038] Next, the operation of the solenoid valve according to the first embodiment will be described with reference to Figures 1 to 6. Figure 3 is a vertical cross-sectional view of the solenoid valve according to the first embodiment when the valve is closed (when current is applied). Figure 4 is an enlarged view of the solenoid portion 10 in Figure 3. Figure 5 is a vertical cross-sectional view of the solenoid valve according to the first embodiment when the valve is in a valve opening transient response (when current is not applied). Figure 6 is an enlarged view of the solenoid portion 10 in Figure 5.

[0039] 1 and 2 , when the solenoid coil 13 is de-energized, the plunger 16 does not generate electromagnetic force. Therefore, the plunger 16 moves together with the rod 15 in a direction away from the valve portion 30 (valve opening direction) due to the retraction force of the coil spring 18 and the biasing force of the coil spring 35. Accordingly, the valve element 34 moves away from the valve seat 33. As a result, the valve element 34 opens, and fluid flows through the flow path 32.

[0040] At this time, gaps having a predetermined length in the axial direction are provided between the other end of the rod 15 and the mounting seat surface 17a of the yoke 17, and between the plunger 16 and the buffer member 19. Therefore, the rod 15 and the yoke 17 do not come into contact with each other when the valve is open. Therefore, even if the size or shape of the rod 15 changes due to frequency of use, moisture absorption, oil absorption, etc., the open state of the valve body 34 remains stable.

[0041] 3 and 4, when the solenoid coil 13 is energized, the plunger 16 generates an electromagnetic force. As a result, the plunger 16 stretches the coil spring 18 in its axial direction and moves together with the rod 15 in a direction approaching the valve element 34 (valve closing direction) against the biasing force of the coil spring 35. As a result, the valve element 34 abuts against the valve seat 33. As a result, the valve element 34 closes, and the flow of fluid is blocked.

[0042] 5 and 6 , if an excessive load is applied to the valve element 34 for some reason when the solenoid coil 13 is de-energized, the other end of the plunger 16 will collide with the buffer member 19. Therefore, the buffer member 19 reduces the impact force of the plunger 16 on the yoke 17, thereby suppressing the impact noise. At this time, the surface pressure generated by the compression reaction force of the buffer member 19 seals the gap between the buffer member 19 and the plunger 16. As a result, fluid is prevented from entering the inside of the plunger 16 from the outside, and fluid is prevented from leaking from the inside of the plunger 16 to the outside.

[0043] Next, the gap f between the rod 15 and the yoke 17 when the valve is open will be described with reference to Fig. 7. Fig. 7 is a diagram for explaining the gap f between the rod 15 and the yoke 17 when the valve is open. Note that reference numerals are omitted in Fig. 7.

[0044] The symbols X and a to f shown in FIG. 7 indicate the following distances. X: opening degree of the valve element 34. a: axial distance between the upper surface of the guide core 14 and the lower surface of the plunger 16. That is, the axial length of the air gap 21. b: axial distance between the upper and lower surfaces of the plunger 16. That is, the axial length of the plunger 16. c: axial distance between the upper surface of the plunger 16 and the mounting seat surface 17a of the yoke 17. d: axial distance between the mounting seat surface 16b of the plunger 16 and the mounting seat surface 17a of the yoke 17. That is, the set distance of the coil spring 18. e: axial distance between the upper surface of the rod 15 and the mounting seat surface 16b of the plunger 16. f: axial distance (gap amount) between the upper surface of the rod 15 and the mounting seat surface 17a of the yoke 17.

[0045] Condition for a: a≧X a is the distance at which magnetism is generated that satisfies the relationship: [(magnetic force generated when a voltage corresponding to the specified minimum operating current is applied + compression load of coil spring 18 + other thrust forces) × (sliding resistance of plunger 16) > (compression load of coil spring 35) + (other resistance forces)].

[0046] Condition for b: b is the distance at which magnetism is generated that satisfies the relationship [(magnetic force generated when a voltage corresponding to the specified minimum operating current is applied + compression load of coil spring 18 + other thrust forces) x (sliding resistance of plunger 16) > (compression load of coil spring 35) + (other resistance forces)].

[0047] Condition for c: c>0

[0048] Conditions for d: d is the distance at which the compressive load of the coil spring 35 is greater than the compressive load of the coil spring 18, or the distance at which the compressive load of the coil spring 18 can be generated, which satisfies the relationship (total mass of the rod 15 and plunger 16 x gravitational acceleration) > (compressive load of the coil spring 18).

[0049] Condition for e: e>(d-c)

[0050] Condition for f: f = d - e

[0051] As described above, the solenoid valve according to the first embodiment comprises a rod 15 having a valve element 34 at one end and at least the other end formed of an elastic resin material having elasticity, a plunger 16 into which the other end of the rod 15 is inserted and which moves in the valve opening direction of the valve element 34 by electromagnetic force, and a yoke 17 provided at the end of which the plunger 16 moves in the valve opening direction, and when the valve element 34 is open, there is a gap between the other end of the rod 15 and the yoke 17. Therefore, even if a volume fluctuation occurs in the portion including the other end of the rod 15 which acts as a buffer member, the solenoid valve can suppress a change in the valve opening degree when the valve is open.

[0052] The solenoid valve according to the first embodiment includes a coil spring 18 that is provided between the plunger 16 and the yoke 17 and through which the rod 15 passes, and a buffer member 19 that is provided on the yoke 17 and against which the plunger 16 can collide, the buffer member 19 being disposed radially outward of the coil spring 18. This allows the solenoid valve to prevent the coil spring 18 from sliding sideways on the yoke 17 when the valve is opened. As a result, the solenoid valve can stably open the valve body 34.

[0053] In the solenoid valve according to the first embodiment, the yoke 17 has a mounting seat surface 17a to which one end of the coil spring 18 is connected and on which the buffer member 19 is provided. Therefore, the solenoid valve can reduce the impact force of the plunger 16 on the yoke 17 by using the buffer member 19, thereby suppressing the impact noise. At this time, the surface pressure generated by the compression reaction force of the buffer member 19 seals the gap between the buffer member 19 and the plunger 16. As a result, the solenoid valve can suppress the intrusion of fluid from the outside of the plunger 16 into the inside, and the leakage of fluid from the inside of the plunger 16 to the outside.

[0054] In the solenoid valve according to the first embodiment, the buffer member 19 has a lip portion 19a that comes into contact with the plunger 16 when the valve is open. When the valve is open, the solenoid valve can prevent foreign matter and fluid from entering the inside of the plunger 16.

[0055] In the manufacturing method of the solenoid valve according to the first embodiment, the rod 15 is press-fitted into the plunger 16. Therefore, the rod 15 and the plunger 16 of the solenoid valve can be coaxially arranged easily and with high precision. As a result, the solenoid valve can stabilize the valve-opening and valve-closing operations. Furthermore, the solenoid valve can be assembled more efficiently.

[0056] In the manufacturing method of the solenoid valve according to the first embodiment, the rod 15 is resin-molded using a molding die into which the plunger 16 is pre-inserted. Therefore, the rod 15 and the plunger 16 can be coaxially arranged easily and with high precision in the solenoid valve. As a result, the solenoid valve can stabilize the valve-opening and valve-closing operations. Furthermore, the solenoid valve can be assembled more efficiently.

[0057] It should be noted that, within the scope of the present disclosure, any of the components of the embodiments may be modified or omitted.

[0058] The solenoid valve of the present disclosure has a gap between the rod and the yoke when the valve body is open, so that even if volume fluctuations occur in the buffer member, changes in the valve opening degree when the valve is open can be suppressed, making it suitable for use in solenoid valves, etc.

[0059] 10 Solenoid portion, 11 Housing, 11a Through hole, 12 Bobbin, 13 Solenoid coil, 14 Guide core, 15 Rod, 16 Plunger, 16a Storage hole, 16b Mounting seat surface, 17 Yoke, 17a Mounting seat surface, 18 Coil spring, 19 Buffer member, 19a Lip portion, 21 Air gap, 30 Valve portion, 31 Housing, 32 Flow path, 33 Valve seat, 34 Valve body, 35 Coil spring.

Claims

1. A solenoid valve comprising: a rod having a valve disc at one end and at least the other end formed of an elastic resin material; a plunger into which the other end of the rod is inserted and which moves in the valve opening direction of the valve disc by electromagnetic force; and a yoke provided at the end of the plunger as it moves in the valve opening direction, wherein when the valve disc is open, there is a gap between the other end of the rod and the yoke.

2. The solenoid valve according to claim 1, further comprising: a coil spring provided between the plunger and the yoke and through which the rod passes; and a buffer member provided on the yoke against which the plunger can collide, the buffer member being positioned radially outward of the coil spring.

3. The solenoid valve according to claim 2, wherein the yoke has a mounting seat surface to which one end of the coil spring is connected and on which the buffer member is provided.

4. The solenoid valve according to claim 2, characterized in that the buffer member has a lip portion that comes into contact with the plunger when the valve is open.

5. A method for manufacturing an electromagnetic valve according to any one of claims 1 to 4, wherein the rod is press-fitted into the plunger.

6. A method for manufacturing a solenoid valve according to any one of claims 1 to 4, characterized in that the rod is resin-molded using a molding die into which the plunger is pre-inserted.

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