JP7387512B2 - pilot operated solenoid valve - Google Patents

Description

The present invention relates to a pilot type solenoid valve equipped with a piston spring for no-differential pressure operation.

A pilot-operated solenoid valve biases the piston away from the valve seat so that the valve opens reliably even when there is no differential pressure between the primary and secondary pressures. A piston spring has been used to forcibly separate the valve body from the valve seat.

Furthermore, in recent years, in order to reduce the cost of parts in pilot-operated solenoid valves, there has been a demand for switching from machined parts to press-formed parts.

Here, a pilot type solenoid valve equipped with a piston spring in which press-processed parts are used for the valve body and the plunger tube (hereinafter referred to as "conventional pilot type solenoid valve") is shown in FIG. 4 of Patent Document 1, for example. etc. are disclosed.

JP 2015-4435 Publication

FIG. 3 is a sectional view showing a conventional pilot type solenoid valve 110. A conventional pilot type solenoid valve 110 includes a valve body 120 having a valve seat 127a, a plunger tube 130, a piston 140 having a pilot flow path 145 and a pressure equalizing hole 147. Furthermore, the conventional pilot type solenoid valve 110 includes a plunger 160 that holds a pilot valve body 161, an attractor 170 that faces the plunger 160 via a coil spring 163, and a control section that is provided on the outer periphery of the small diameter section 132 of the plunger tube 130. (not shown).

Here, the upper opening of the valve chamber 126 of the valve body 120 has a leg portion 128 directed in the outer diameter direction, and a plunger tube 130 is joined onto the receiving portion 129 by welding W. Further, an inflow pipe 101 and an outflow pipe 102 are joined to the valve body 120 by brazing and communicate with a valve chamber 126 . Further, the piston 140 is slidably disposed on the sliding surface 134 of the plunger tube 130, and a piston spring 150 disposed between the leg portion 128 of the valve body 120 and the piston 140 causes the piston 140 to move toward the valve seat. It is biased in the direction away from 127a.

However, the conventional pilot type solenoid valve 110 mainly has the following three problems. The first problem is that the valve body 120, which is biased by the piston spring 150, needs to be joined to the plunger tube 130 by welding W. In other words, since a special jig is used to weld the valve body 120 and the plunger tube 130 while holding them together, it is extremely difficult to arrange the valve body 120 and the plunger tube 130 coaxially (hereinafter referred to as " (Difficulty coaxially arranging press members.) The second problem is that the leg portion 128 of the valve body 120 serves as a receiving seat for the lower end of the piston spring 150, but since the piston spring 150 is not seated properly, there is a risk of displacement in the radial direction. (hereinafter referred to as "piston spring misalignment"). As a third problem, since the piston 140 is supported by the sliding surface only at the upper end of the piston 140, there is a possibility that the piston 140 is likely to tilt (hereinafter referred to as "piston tilt").

The present invention solves at least one of the above-mentioned problems, and aims to provide a pilot type solenoid valve that uses press-formed parts and is equipped with a piston spring that is easy to assemble.

In order to solve the above problems, a pilot-operated solenoid valve has a piston having a pilot flow path, a large diameter part in which a valve chamber and a valve seat are provided on which one end side of the piston comes into contact with and leaves, and a reduced diameter part that accommodates the piston. A valve body, a piston spring that biases the piston in a direction away from the valve seat, a pilot valve element that opens and closes the pilot flow path, an enlarged diameter portion that accommodates the piston, and a plunger that provides the pilot valve element. a plunger tube having a small diameter portion that slidably guides the plunger; and a control unit that drives the plunger, the piston spring being press-fitted into a flange provided on the piston and an enlarged diameter portion of the plunger tube. The plunger tube is held between the other end of the reduced diameter portion of the valve body, and is housed in an annular space defined by the side wall of the piston and the enlarged diameter portion of the plunger tube.

Further, the pilot type solenoid valve may be such that the piston is slidably guided by a reduced diameter portion of the valve body and an enlarged diameter portion of the plunger tube.

Further, the pilot type solenoid valve has a first sub-flow path formed between a side wall of the piston and a reduced diameter portion of the valve body, a flange portion of the piston, and an enlarged diameter portion of the plunger tube. a second sub-flow path formed between the pilot flow path, and a capacity coefficient (Cv value) of at least one of the first sub-flow path and the second sub-flow path, It may be made smaller than the capacity coefficient (Cv value).

According to the present invention, it is possible to provide a pilot type solenoid valve that uses press-processed parts and includes a piston spring that is easy to assemble.

1 is a cross-sectional view showing a closed state of a pilot-operated solenoid valve according to an embodiment of the present invention, in which (a) is an overall view of the pilot-operated solenoid valve, and (b) is a broken line I(b) in (a). FIG. 3 depicts an enlarged view of the connection between the enclosed valve body and the plunger tube, respectively. 2 is a cross-sectional view showing a pilot-operated solenoid valve in an open state according to an embodiment of the present invention, in which (a) is an overall view of the pilot-operated solenoid valve, and (b) is a diagram along the broken line II (b) in (a). FIG. 3 depicts an enlarged view of the connection between the enclosed valve body and the plunger tube, respectively. FIG. 2 is a sectional view showing a conventional pilot type solenoid valve.

Embodiments of the present invention will be described in detail with reference to FIGS. 1 and 2. However, the present invention is not limited to the aspects of this embodiment.

<About terms>
In this specification and claims, "one end" and "other end" refer to "lower" and "upper" in the drawings.

<About the configuration of the pilot operated solenoid valve>
A pilot type solenoid valve 10 according to an embodiment of the present invention will be described using FIGS. 1 and 2. The pilot type solenoid valve 10 mainly includes a valve body 20, a plunger tube 30, a piston 40, a piston spring 50, a plunger 60, an attractor 70, and a control section 80. Hereinafter, each configuration of the pilot type solenoid valve 10 will be explained.

The valve body 20 is formed by press working, and includes a cylindrical large diameter portion 21 extending toward one end in the axial direction, and a cylindrical contracted portion extending from the large diameter portion 21 toward the other end in the axial direction. A diameter portion 22 is provided. A shoulder portion 23 is formed at the joint between the large diameter portion 21 and the reduced diameter portion 22. A valve seat body 27 provided with a valve seat 27a and an outflow pipe 2 into which a secondary side pressure, which is a low pressure side, is introduced are joined to one end side opening 24 of the valve body 20 by brazing. Further, the inflow pipe 1 into which the primary side pressure, which is a high pressure side, is introduced is connected to the side opening 25 of the valve body 20 by brazing and communicates with the valve chamber 26 . Here, the pipe thickness of the valve body 20 is set to be the same as or slightly larger than the wire diameter of the piston spring 50.

The plunger tube 30 is formed by press working, and includes a cylindrical enlarged diameter portion 31 extending toward one end in the axial direction, and a cylindrical small diameter portion extending from the enlarged diameter portion 31 toward the other end in the axial direction. 32. A stepped portion 33 is formed at the joint between the enlarged diameter portion 31 and the small diameter portion 32. The reduced diameter portion 22 of the valve body 20 is press-fitted into the enlarged diameter portion 31 of the plunger tube 30 with a predetermined press fit allowance L without requiring any special jig. Here, the inner diameter of the enlarged diameter portion 31 of the plunger tube 30 is set to be slightly smaller than the outer diameter of the reduced diameter portion 22 of the valve body 20. Moreover, this press-fitting allowance L is the length until the tip of the enlarged diameter part 31 of the plunger tube 30 comes into contact with the shoulder part 23 of the valve body 20 when press-fitting and fixing, that is, the length of the reduced diameter part of the valve body 20. This corresponds to the axial length of 22. In order to obtain this press-fit allowance L, as the press-fit fixation in the axial direction progresses, the valve body 20 and the plunger tube 30 are positioned coaxially in order to perform positioning in the radial direction by sliding their opposing surfaces. can do. Thereby, the pilot type solenoid valve 10 according to the present embodiment can solve the first problem mentioned above (difficulty coaxially arranging the press members).

The press-fitting allowance L in this embodiment is preferably 2 to 4 (mm). Furthermore, although the means for fixing the plunger tube 30 and the valve body 20 in this embodiment is only by press-fitting, the present invention is not limited to this. For example, in order to make this fixing means more solid and to suppress distortion due to the influence of heat, after press-fitting and fixing, laser welding, spot welding, etc. It can be carried out.

The piston 40 includes a valve body 41 that is provided at one end and is in contact with and separates from the valve seat 27a, and a side wall 43 that extends to the other end and has a flange portion 42 oriented in the outer diameter direction at the other end. . Furthermore, as shown in FIG. 1(b), the piston 40 has a pilot valve chamber 44 formed of a recess provided on the other end side, and a pilot flow path 45 that communicates the central opening of the valve body 41 with the pilot valve chamber 44. , is provided. Note that it is not an essential configuration that the piston 40 of this embodiment includes the pilot valve chamber 44. Furthermore, although the flange portion 42 in this embodiment is provided at the other end of the piston 40, the flange portion 42 is not limited thereto, and may be provided at any position in the axial direction on the side wall 43, or may be provided at any position in the axial direction on the side wall 43. It may be provided extending to. Here, the plunger tube 30 and the valve body 20 are press-fitted and fixed with the piston spring 50 being sandwiched between the flange portion 42 of the piston 40 and the other end of the reduced diameter portion 22 of the valve body 20. Thereby, the piston spring 50 is accommodated in the annular space Cs defined by the side wall 43 of the piston 40 and the enlarged diameter portion 31 of the plunger tube 30 without requiring a special jig. Therefore, the pilot type solenoid valve 10 according to the present embodiment can suppress displacement of the piston spring 50 in the radial direction and improve seating, thereby solving the second problem (misalignment of the piston spring) mentioned above. Can be done. Here, although the details will be described later, this piston spring 50 moves the valve body 41 in the direction away from the valve seat 27a even in the case of no differential pressure where there is no pressure difference between the primary side pressure and the secondary side pressure. It is constructed of a relatively weak spring constant that has a certain amount of biasing force. Note that "inside the annular space Cs" in which the piston spring 50 is accommodated in this embodiment refers to the inside of the annular space Cs defined by the side wall 43 of the piston 40 and the enlarged diameter portion 31 of the plunger tube 30. . This "inside the annular space Cs" includes a part of the space included in the annular space Cs, for example, a piston when a cylindrical sleeve is inserted into the inner circumferential side of the enlarged diameter part 31 of the plunger tube 30. An annular space defined by the side wall 43 of 40 and the inner peripheral surface of the sleeve is included.

The plunger 60 includes a pilot valve body 61 held at one end to open and close the pilot flow path 45, and a recess 62 formed at the other end. The plunger 60 is slidably guided in the small diameter portion 32 of the plunger tube 30 in the axial direction. The coil spring 63, in a compressed state, is held between the recess 62 of the plunger 60 and an attractor 70 fixed to the other end of the small diameter portion 32, and the coil spring 63 is held in a compressed state so as to move the plunger 60 downward, that is, in the direction of the valve seat 27a. The piston 40 is urged to

The control unit 80 includes an electromagnetic coil 81 and a magnetic frame 82 , is disposed on the outer periphery of the small diameter portion 32 of the plunger tube 30 , and drives the plunger 60 . This electromagnetic coil 81 is mounted inside a magnetic frame 82 and includes a bobbin 83 around which a winding is wound, and a mold resin 84 that molds the periphery of the bobbin 83. In the control unit 80, a fastening bolt 85 is screwed into a female thread 71 formed on the upper part of the attractor 70 through a bolt insertion hole 82a formed in the magnetic frame 82.

<About the operation of pilot operated solenoid valve>
The operation of the pilot type solenoid valve 10 having the configuration described above will be explained. The pilot-operated solenoid valve 10 has primary pressure (high pressure) introduced through the inflow pipe 1 and secondary pressure (low pressure) introduced through the outflow pipe 2. It is assumed that a pressure difference occurs between the pressure on the next side and the pressure on the next side.

(State where power to the electromagnetic coil is cut off)
As shown in FIG. 1, the plunger 60 moves in a direction away from the attractor 70 due to the biasing force of the coil spring 63. As a result, the pilot valve body 61 held at one end of the plunger 60 is seated on the pilot valve seat 46 formed in the upper part of the pilot flow path 45 of the piston 40, thereby closing the pilot flow path 45.

Further, as the plunger 60 further moves in the direction away from the suction element 70 together with the piston 40, the valve body 41 seats on the valve seat 27a provided in the valve body 20, and the valve body 41 is seated on the valve seat 27a provided in the valve body 20. The valve port 27b is closed.

Here, a sub-flow path is formed on the outer peripheral side of the piston 40, which constantly communicates the valve chamber 26 and the pilot valve chamber 44. This sub-flow path includes an annular first sub-flow path Sf1 formed between the side wall 43 of the piston 40 and the reduced diameter portion 22 of the valve body 20, and an enlarged flange portion 42 of the piston 40 and the plunger tube 30. and an annular second sub-flow path Sf2 formed between the diameter portion 31 and the radial portion 31.

Therefore, when the pilot flow path 45 and the valve port 27b are in the closed state, the fluid in the inflow pipe 1 on the high pressure side flows through the first sub-flow path Sf1 and the second sub-flow path Sf2. It flows into the pilot valve chamber 44. Thereby, in addition to the biasing force of the coil spring 63, the high pressure in the pilot valve chamber 44 biases the valve body 41 in a direction to bring it into contact with the valve seat 27a.

(When the electromagnetic coil is energized)
As shown in FIG. 2, the plunger 60 moves in the direction of the attractor 70 against the biasing force of the coil spring 63. As a result, the pilot valve body 61 held at one end of the plunger 60 moves in a direction away from the pilot valve seat 46 formed at the upper part of the pilot passage 45 of the piston 40, opening the pilot passage 45. Set to valve state.

At this time, as shown in FIG. 2(b), the high pressure fluid in the pilot valve chamber 44 of the piston 40 is discharged to the outflow pipe 2 on the low pressure side via the pilot flow path 45 (arrow E reference). On the other hand, the pilot valve chamber 44 of the piston 40 is supplied with fluid from the inflow pipe 1 via the first sub-flow path Sf1 and the second sub-flow path Sf2 (see arrow F). Therefore, in order to reliably generate a pressure difference in the piston 40 and move the piston 40 in the direction away from the valve seat 27a, it is necessary to make the supply flow rate to the pilot valve chamber 44 smaller than the discharge flow rate. For this reason, the capacity coefficient (Cv value) of at least one of the first sub-flow path Sf1 and the second sub-flow path Sf2 is set smaller than the capacity coefficient (Cv value) of the pilot flow path 45. The settings of the capacity coefficients (Cv values) in the first sub-flow path Sf1, the second sub-flow path Sf2, and the pilot flow path 45 can be adjusted by adjusting the opening area of the flow path, the length of the flow path, and the like.

In this embodiment, the capacity coefficient (Cv value) of at least one of the first sub-flow path Sf1 and the second sub-flow path Sf2 is made smaller than the capacity coefficient (Cv value) of the pilot flow path 45. . Here, the valve body 20 and plunger tube 30 that define the first sub-flow path Sf1 and the second sub-flow path Sf2 require a relatively large number of steps in order to perform dimensional control with high processing accuracy. It is formed by press working. Therefore, instead of controlling the dimensions of both the valve body 20 and the plunger tube 30, which are formed by press working, with high processing accuracy, it is possible to improve productivity by controlling the dimensions of at least one of them. can be increased.

In this way, the pressure in the pilot valve chamber 44, which the piston 40 receives from above, decreases, and a pressure difference is generated between the pressure in the pilot valve chamber 44, which the piston 40 receives from below, and the primary side pressure (high pressure), which the piston 40 receives from below. It moves in the direction away from the seat 27a, and the valve port 27b becomes open. When the piston 40 further moves in the direction away from the valve seat 27a, the stepped portion 33 of the plunger tube 30 comes into contact with the flange portion 42 of the piston 40 and functions as a stopper, thereby limiting the maximum opening of the valve body 41. stipulated.

Here, the side wall 43 of the piston 40 and the reduced diameter part 22 of the valve body 20 provide a first sliding surface Ss1, and the flange part 42 of the piston 40 and the enlarged diameter part 31 of the plunger tube 30 provide a first sliding surface Ss1. Two sliding surfaces Ss2 are provided. The first sliding surface Ss1 and the second sliding surface Ss2 are spaced apart from each other in the axial direction with the piston spring 50 in between, and correspond to the first sub-flow path Sf1 and the second sub-flow path Sf2. located at the location. As a result, the pilot type solenoid valve 10 in this embodiment supports the piston 40 on two sliding surfaces that are spaced apart in the axial direction, so that the piston 40 can be slidably guided without tilting. Therefore, the third problem (inclination of the piston) mentioned above can be solved.

In addition, in the above description, it is assumed that a pressure difference occurs between the primary side pressure and the secondary side pressure. However, even when there is no pressure difference between the primary side pressure and the secondary side pressure, the piston spring 50 biases the piston 40 in the direction away from the valve seat 27a, thereby opening the valve. The operation can be performed reliably.

<Others>
The pilot type solenoid valve of this embodiment is applicable to all fluid devices and fluid circuits. Furthermore, the present invention is not limited to the above-described forms, embodiments, and modifications described elsewhere, but can be modified and modified as appropriate without departing from the technical idea of the present invention.

10 Pilot type solenoid valve 1 Inflow pipe 2 Outflow pipe 20 Valve body 21 Large diameter part 22 Reduced diameter part 23 Shoulder part 24 One end side opening 25 Side opening 26 Valve chamber 27 Valve seat body 27a Valve seat 27b Valve port 30 Plunger Tube 31 Expanded diameter part 32 Small diameter part 33 Step part 40 Piston 41 Valve body 42 Flange part 43 Side wall 44 Pilot valve chamber 45 Pilot flow path 50 Piston spring 60 Plunger 61 Pilot valve body 70 Suction element 80 Control part Cs Annular space L Press-fit allowance Sf1 First sub-flow path Sf2 Second sub-flow path Ss1 First sliding surface Ss2 Second sliding surface

Claims (3)

a piston having a pilot flow path;
a valve body having a large diameter portion that includes a valve chamber and a valve seat where one end side of the piston comes into contact with and leaves the piston, and a reduced diameter portion that accommodates the piston;
a piston spring that urges the piston in a direction away from the valve seat;
a pilot valve body that opens and closes the pilot flow path;
a plunger tube having an enlarged diameter part that accommodates the piston, and a small diameter part that slidably guides a plunger provided with the pilot valve body;
a control unit that drives the plunger;
Equipped with
The piston spring is sandwiched between a flange provided on the piston and the other end of the reduced diameter portion of the valve body press-fitted into the enlarged diameter portion of the plunger tube, and is connected to a side wall of the piston. A pilot type solenoid valve, wherein the pilot type solenoid valve is housed in an annular space defined by the enlarged diameter portion of the plunger tube. The pilot type solenoid valve according to claim 1, wherein the piston is slidably guided by a reduced diameter portion of the valve body and an enlarged diameter portion of the plunger tube. a first sub-flow path formed between a side wall of the piston and a reduced diameter portion of the valve body; and a second sub-flow path formed between a flange portion of the piston and an enlarged diameter portion of the plunger tube. having a sub-flow path;
Claim 1 or 2, wherein a capacity coefficient (Cv value) of at least one of the first sub-channel and the second sub-channel is made smaller than a capacity coefficient (Cv value) of the pilot channel. The pilot type solenoid valve according to claim 2.

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