JP2007032783A - Solenoid valve - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a solenoid valve capable of allowing magnetic flux necessary and sufficient for generating electromagnetic force to flow, and improving suction force characteristic by reducing resistance when fluid flows. <P>SOLUTION: This solenoid valve 10 has a case 12, a yoke 14, a core 15, a plunger 18, a coil 21 or the like. The case 12 comprises the yoke 14 axially reciprocatably receiving the plunger 18, the core 15 generating magnetic force for sucking the plunger 18 to a spool side, and a flange portion 19 in a state of being integrally molded. The plunger 18 is slidably supported on an inner wall surface of the yoke 14, and a through hole 20 as a fluid passage is axially formed from a spool-side end face to an anti spool-side end face of the plunger 18. The through hole 20 is provided with a hole 20a at the spool end face side and a hole 20b at the anti spool-side end face side in a state that a hole diameter of the hole 20a is smaller than that of the hole 20b. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a solenoid valve, and more particularly to a solenoid valve that improves attraction force characteristics.

Conventionally, this type of solenoid valve 1 has a housing 31 having a plurality of fluid flow paths 32 to 35 on a cylindrical wall, and a spool 30 for switching the fluid flow paths 32 to 35 by reciprocating in the housing 31. A plunger 18 arranged in series in the axial direction of the spool 30;
It has a cylindrical yoke that holds the plunger 18, a stator core 15 that is a fixed iron core, a coil 21 that applies electromagnetic force, and a case 22 that is a resin molded body. The plunger 18 includes
A through hole 20 is formed eccentrically in the axial direction from the spool side end surface to the non-spool side end surface. The through-hole 20 has a function as a breathing passage for ensuring a passage cross-sectional area sufficient for the hydraulic oil to move along with the movement of the plunger 18 (see, for example, Patent Document 1).
JP 2002-243057 A

However, in the solenoid valve described in Patent Document 1, it is necessary to avoid the contact portion of the spool on the end surface on the side of the fixed iron core and provide the through hole. When the viscosity of the fluid is high, there is a problem that the fluid cannot sufficiently flow and the responsiveness is deteriorated.
The present invention has been made to solve the above-described problems, and can provide a magnetic flux necessary and sufficient to generate electromagnetic force, and improve attraction force characteristics by reducing resistance when the fluid flows. An object is to provide a solenoid valve.

The invention according to claim 1 is a sleeve having a plurality of fluid flow paths in a cylindrical wall;
A spool that switches the fluid flow path by reciprocating in the sleeve;
A plunger arranged in series in the axial direction of the spool;
A case for holding a cylindrical core for supporting the plunger and a coil for applying electromagnetic force;
With
The plunger forms an oil passage that penetrates the spool side end surface and the non-spool side surface.
According to the present invention, the movement of the plunger can be improved without affecting the electromagnetic force, and the responsiveness can be improved. Since it is necessary for the core side to concentrate magnetic flux on the core, it is better that the oil passage has a smaller hole diameter.
In the invention of claim 2, since the hole diameter of the oil passage is formed larger on the spool end surface side than the hole diameter on the anti-spool end surface side, a flat surface is secured at the spool abutting portion and at the same time on the spool side end surface of the plunger. Magnetic flux can be concentrated.

The present invention can improve the responsiveness by improving the movement of the plunger without affecting the electromagnetic force. Since it is necessary for the core side to concentrate magnetic flux on the core, it is better that the oil passage has a smaller hole diameter. By making the core side small in diameter, it is possible to flow a magnetic flux necessary and sufficient to generate an electromagnetic force at the same time as ensuring a flat surface in the spool contact portion.
On the other hand, by increasing the diameter of the anti-core side, the resistance through which the pressure fluid flows can be reduced, and since the magnetic flux density is relatively low on the anti-core side, there is almost no influence on the electromagnetic force.

A solenoid valve according to an embodiment of the present invention will be described in detail with reference to the drawings. FIG. 1 is a longitudinal sectional view showing a schematic structure of a solenoid valve 10 according to a first embodiment of the present invention.
As shown in FIG. 1, the electromagnetic valve 10 has a case 12, a core 15, a yoke 14, a plunger 18, a coil 21, and the like. In this case, the case 12, the core 15, the yoke 14, and the plunger 18 are made of a magnetic material. The solenoid 11 is formed of a case 12, a core 13, a yoke 14, a plunger 18, a coil 21, and the like.

The yoke 14 and the core 15 have a cylindrical peripheral wall surface and are coaxially formed in this order from the non-spool side toward the spool side. The flange portion 19 is formed on the outer periphery of the suction portion 15 at the spool side pipe end portion of the bobbin 13 and is sandwiched between the case 12 and the sleeve 30.
The coil 21 is sealed by the resin molded body 22 and accommodated in a space formed by the outer peripheral wall of the bobbin 13 and the inner peripheral wall of the case 12. When a current is supplied to the coil 21 from a terminal (not shown) electrically connected to the coil 21, a magnetic flux flows through a magnetic circuit formed by the case 12, the plunger 18, and the bobbin 13, and the core 15, the plunger 18, Magnetic attractive force is generated during Thereby, the plunger 18 and the spool 31 are displaced in the arrow Y direction.

  The plunger 18 is slidably supported on the inner wall surface of the yoke 14. A through hole (oil passage) 20 as a fluid passage is formed in the axial direction from the spool side end surface of the plunger 18 to the counter spool side end surface. The through-hole 20 has a hole diameter formed in the hole 20a on the spool end face side and a hole 20b on the opposite spool end face side, and the hole diameter of the hole 20a is smaller than that of the hole 20b. Thereby, magnetic flux can be concentrated on the spool side end surface of the plunger 18. Furthermore, by forming the hole 20b larger than the hole 20a on the side opposite to the spool end surface, the resistance of fluid flow can be reduced.

The sleeve 30 has a cylindrical shape, and a spool 31 is removably fitted therein. In the sleeve 30, an input port (fluid flow path) 32, an output port (fluid flow path) 33, a feedback port (fluid flow path) 34 and a drain port (fluid flow path) 35 are formed in this order.
The input port 32 has a function of allowing pressure fluid supplied by a pump from a tank (not shown) to flow in. The output port 33 is a port for supplying pressure fluid to an operating device such as an automatic transmission (not shown). The output port 33 and the feedback port 34 communicate with each other outside the solenoid valve 10 (not shown), and a part of the pressure fluid flowing out from the output port 33 flows into the feedback port 34. The feed bag chamber 36 communicates with the feed bag port 34. The drain port 35 has a function of discharging the pressure fluid to a tank (not shown).

  In the spool 31, lands 37, 38, and 39 are formed in this order from the side opposite to the plunger. Here, the land 39 has an outer diameter smaller than that of the lands 37 and 38. At both ends of the spool 31, shafts 40 and 41 having a smaller diameter than the outer diameters of the lands 37 to 39 are formed. The shaft 40 protrudes toward the suction part 15 side of the core 13, and the tip part is in contact with the center part of the end face of the plunger 18. On the other hand, the shaft 41 projects into the space 42 of the sleeve 31.

The spring member 43 wound around the shaft 41 and housed in the space portion 42 urges the spool 31 toward the plunger side by the elastic force adjusted by the tightening amount of the adjuster 44 screwed to the end surface of the sleeve 30. Yes. Thus, the spool 31 is urged in the arrow X direction by the plunger 18, and is urged in the arrow X direction together with the plunger 18 by the elastic force of the spring member 43, thereby cooperating with the plunger 18 and the sleeve 30. The inside is displaced in the directions of arrows X and Y.
The feed bag chamber 36 is formed between the land 38 and the land 39, and the pressure receiving area on which the pressure fluid fed back acts varies depending on the outer diameter difference between the land 38 and 39. Therefore, the fluid in the feedback bag chamber 36 acts to press the spool 31 in the arrow Y direction (anti-solenoid direction). In this case, part of the fluid output from the electromagnetic valve 10 is fed back in order to prevent the output pressure from fluctuating due to fluctuations in the pressure of the supplied fluid, that is, the input pressure.

The spool 31 receives the spool 31 from the fluid in the feedback chamber 36 and the force by which the plunger 18 pushes the spool 31 by the elastic force of the spring member 43 and the electromagnetic force generated in the core 13 by the current supplied to the coil 21. It stops at a position where the force balances.
The flow rate of the pressure fluid flowing from the input port 32 to the output port 33 is determined by the seal length of the overlapping portion between the inner peripheral wall 31 a of the sleeve 30 and the outer peripheral wall of the land 38. That is, when the seal length is shortened, the flow rate of the fluid flowing from the input port 32 to the output port 33 is increased, and when the seal length is increased, the flow rate of the fluid flowing from the input port 32 to the output port 33 is decreased. Similarly, the flow rate of the fluid flowing from the output port 33 to the drain port 35 is determined by the seal length between the inner peripheral wall 31 b of the sleeve 30 and the outer peripheral wall of the land 37.

When a current is applied to the coil 21, the spool 31 is displaced in the arrow Y direction by the exciting force of the coil 21, the seal length between the inner peripheral wall 31 a and the land 38 is shortened, and the inner peripheral wall 31 b and the land 37 are The seal length becomes longer. As a result, the flow rate of the pressure fluid flowing from the input port 32 to the output port 33 decreases. Therefore, the pressure of the pressure fluid flowing out from the output port 33 increases.
The solenoid valve 10 controls the value of the current supplied to the coil 21 so that the solenoid 11 adjusts the pressing force of the spool 31 in the direction of the anti-solenoid 11 and adjusts the hydraulic pressure of the fluid flowing out from the output port 33. When the value of the current flowing through the coil 21 is increased, the electromagnetic force of the core 15 increases in proportion to the current value, and the force by which the shaft 40 pushes the spool 31 in the anti-solenoid 11 direction (arrow Y direction) increases. The spool is at a position where the force acting on the spool 31 from the plunger 18 by this electromagnetic force, the resilience of the spring member 40, and the force by which the spool 31 is pushed in the anti-linear solenoid direction (arrow Y direction) by the pressure of the fluid fed back. 31 stops. Therefore, the hydraulic pressure of the pressure fluid flowing out from the output port 33 decreases in proportion to the current value energized in the coil 21.

In the solenoid valve 10 shown in FIG. 1, the plunger 18 has a through hole 20 penetrating from the spool side end surface to the non-spool side end surface, and holes 20 a and 20 b are formed. That is, the hole diameter of the plunger 18 is formed in a stepped hole having a diameter change with the core 13 side having a small diameter and the anti-core 13 side having a large diameter. Thereby, the movement of the plunger 18 becomes favorable without affecting the electromagnetic force, and the responsiveness can be improved. Since the solenoid valve 10 needs to concentrate the magnetic flux on the core 15, the hole diameter of the through hole 20 is preferably small.
For this reason, in the electromagnetic valve 10 shown in FIG. 1, a flat surface can be secured at the contact portion of the spool 31 by reducing the diameter of the core 15 side, and a magnetic flux necessary and sufficient to generate an electromagnetic force can flow. it can. On the other hand, by increasing the diameter of the anti-core 15 side, the resistance through which the pressure fluid flows can be reduced, and since the magnetic flux density is relatively low on the anti-core 15 side, there is almost no influence on the electromagnetic force.
In the electromagnetic valve 10 according to the first embodiment, one through hole 20 is provided in the plunger 18, but a plurality, for example two, may be arranged on the end face of the plunger 18 at symmetrical positions in the diameter direction. Good. Thereby, responsiveness can be further improved.

FIG. 2 is a longitudinal cross-sectional view of a solenoid valve 50 according to the second embodiment of the present invention. In FIG. 2, the same components as those of FIG. To do.
This solenoid valve 50 has a rod 52 fitted into a plunger 51, slidably supported by a bearing mechanism 54 fitted into a core 53 having a fixed iron core function, and its tip is attached to the shaft 40 of the spool 31. It is made to contact | abut.
As shown in FIG. 3, the plunger 51 is formed with a pair of through holes 55 and 56 in the axial direction in a symmetric position with respect to the axial center. The spacer 57 is provided at an engaging portion between the end surface of the plunger 51 and the rod 52, and has a function of preventing inseparability by closely contacting the end surface of the core 13 when the plunger 51 is displaced. Instead of the spacer 57, a protruding portion that is larger than the outer diameter of the plunger 51 may be formed at a site where the plunger 51 is engaged.

It is a schematic longitudinal cross-sectional view of the solenoid valve which concerns on 1st embodiment of this invention. It is a schematic longitudinal cross-sectional view of the solenoid valve which concerns on 2nd embodiment of this invention. It is a longitudinal cross-section which shows the engagement state of the plunger and rod of FIG.

Explanation of symbols

10, 50 Solenoid valve 11 Solenoid 12 Case 15, 53 Core 18, 50 Plunger 20, 54, 55 Through hole 21 Coil 13, 22 Bobbin (or resin molding)
30 Sleeve 31 Spool 32 Input port 33 Output port 34 Feedback port 35 Drain port 36 Feedback chamber 37-39 Land 40, 41 Shaft

Claims (2)

A sleeve having a plurality of fluid flow paths in a cylindrical wall;
A spool that switches the fluid flow path by reciprocating in the sleeve;
A plunger arranged in series in the axial direction of the spool;
A case for holding a cylindrical core for supporting the plunger and a coil for applying electromagnetic force;
With
The solenoid valve according to claim 1, wherein the plunger forms an oil passage penetrating the spool side end surface and the anti-spool side surface. The solenoid valve according to claim 1, wherein
The solenoid valve according to claim 1, wherein the oil passage is formed such that a hole diameter thereof is larger on a side of the spool end face than on a side opposite to the spool end face.

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