Solenoid valve and its control method

Abstract

The present invention provides a solenoid valve and a control method therefor that can maintain the valve body seated on the valve seat with low power consumption when the solenoid is energized. [Solution] The solenoid valve 100 includes a first valve seat 126 and a second valve seat 128 formed inside the body 106 between the supply port 108 and the discharge ports 110 and 112, respectively; a valve body 114 movably positioned inside the body between the first valve seat and the second valve seat; a pin 116 movably clearance-fitted into the shaft hole 114a of the valve body; a plunger 104 that moves integrally with the pin; a stopper 118 positioned at one end of the plunger's stroke; a solenoid 102 that moves the plunger and pin toward the first valve seat; a relay spring 120 attached to the pin that biases the valve body toward the first valve seat; and a return spring 122 that biases the valve body toward the second valve seat. The pin is movable even after the valve body has seated on the first valve seat when the solenoid is energized, until the plunger contacts the stopper.

Description

Technical Field

[0001] The present invention relates to a solenoid valve including a solenoid and a plunger, and a control method therefor.

Background Art

[0002] As an example of a solenoid valve, a solenoid valve includes a solenoid, a valve body (body) having a supply port and two discharge ports, and a movable iron core (plunger) slidably disposed inside the body. The solenoid valve switches a flow path by displacing the plunger by an attractive force generated when the solenoid is energized.

[0003] Patent Document 1 describes a flow path switching solenoid valve including a coil (solenoid), a plunger, two valve seats formed in a body, a valve body, a compression spring (spring), and a core (stopper) which is a fixed iron core.

[0004] The valve body moves together with the plunger to open and close each of the valve seats. The body has one supply port and two discharge ports disposed on both sides of the supply port (three-way valve). Further, in the flow path switching solenoid valve, the concentricity between the body and the valve body is ensured by press-fitting and positioning the valve body on the plunger.

[0005] In the flow path switching solenoid valve of Patent Document 1, when the coil is not energized, the valve body seats on "one of the valve seats" by the biasing force of the spring. The valve seat on which the valve body seats closes, and "the other valve seat" opens.

[0006] When the coil is energized, the plunger is attracted to the stopper by the attractive force of the coil, so the valve body seats on "the other valve seat". When "the other valve seat" closes, "one of the valve seats" opens. In this way, in the flow path switching solenoid valve, the flow path is switched by moving the valve body.

Prior Art Documents

Patent Documents

[0007] [Patent Document 1] Patent No. 7304497 [Overview of the Initiative] [Problems that the invention aims to solve]

[0008] In the flow path switching solenoid valve of Patent Document 1, the valve body is press-fitted into the plunger and moves as a single unit. Therefore, considering variations in the dimensions of the parts, a gap (magnetic gap) must be provided between the plunger and the stopper when the valve body is seated on the valve seat during energization. If a magnetic gap is not provided, depending on the variations in the dimensions of the parts, it may not be possible to seat the valve body on the valve seat at all.

[0009] However, if there is a magnetic gap between the plunger and the stopper, the attractive force between the plunger and the stopper decreases inversely proportional to the square of the distance. Therefore, in order to hold the valve body with the attractive force of the electromagnet, even a slight increase in the magnetic gap will cause a dramatic increase in power consumption.

[0010] In view of these problems, the present invention aims to provide a solenoid valve and a control method therefor that can maintain the valve body seated on the valve seat with low power consumption when the solenoid is energized. [Means for solving the problem]

[0011] To solve the above problems, a typical configuration of the solenoid valve according to the present invention includes a valve seat formed inside the body, a valve body seated on the valve seat, a pin movably clearance-fitted into a shaft hole formed in the valve body, a plunger that moves integrally with the pin, a stopper which is a fixed iron core located between the plunger and the valve body and positioned at one end of the plunger's stroke, a solenoid that moves the plunger and pin toward the valve seat, a relay spring attached to the pin that biases the valve body toward the valve seat, and a return spring that biases the valve body toward the direction away from the valve seat, wherein the pin is movable even after the valve body has seated on the valve seat when the solenoid is energized, until the plunger comes into contact with the stopper.

[0012] To solve the above problems, another typical configuration of the solenoid valve according to the present invention includes a body having one supply port and two discharge ports located on both sides of the supply port; a first valve seat and a second valve seat formed inside the body between the supply port and each of the two discharge ports; a valve body movably positioned inside the body between the first valve seat and the second valve seat and seating on the first valve seat or the second valve seat; a pin movably clearance-fitted into a shaft hole formed in the valve body; a plunger that moves integrally with the pin; a stopper which is a fixed iron core located between the plunger and the valve body and positioned at one end of the plunger's stroke; a solenoid that moves the plunger and the pin toward the first valve seat; a relay spring attached to the pin that biases the valve body toward the first valve seat; and a return spring that biases the valve body toward the second valve seat, wherein the pin is movable even after the valve body has seated on the first valve seat when the solenoid is energized, until the plunger contacts the stopper.

[0013] The initial load of the intermediate spring described above is preferably greater than the compressive load of the return spring.

[0014] To solve the above problems, a typical configuration of the solenoid valve control method according to the present invention is to use the above-mentioned solenoid valve to reduce the current applied to the solenoid after the plunger contacts the stopper. [Effects of the Invention]

[0015] According to the present invention, it is possible to provide a solenoid valve and a control method therefor that can maintain the valve body seated on the valve seat with low power consumption when the solenoid is energized. [Brief explanation of the drawing]

[0016] [Figure 1] This is an overall configuration diagram of a solenoid valve in an embodiment of the present invention. [Figure 2] This diagram illustrates the operation of the solenoid valve shown in Figure 1. [Figure 3] This diagram shows the main components of the solenoid valve shown in Figure 2(a). [Figure 4] It is a diagram showing the main part of the solenoid valve in Fig. 2(b). [Figure 5] It is a diagram showing the main part of the solenoid valve in Fig. 2(c). [Figure 6] It is a diagram showing the main part of the solenoid valve in Fig. 2(d). [Figure 7] It is a graph showing the characteristics of the solenoid valve in the embodiment of the present invention. [Figure 8] It is a diagram showing an embodiment in which one discharge port is blocked to form a two-way valve. [Figure 9] It is a diagram showing an embodiment in which the discharge ports are combined into one to form a two-way valve.

Mode for Carrying Out the Invention

[0017] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. Dimensions, materials, and other specific numerical values shown in such embodiments are merely examples for facilitating understanding of the invention, and do not limit the present invention unless otherwise specified. In this specification and the drawings, elements having substantially the same function and configuration are denoted by the same reference numerals to omit redundant description, and elements not directly related to the present invention are not shown.

[0018] Fig. 1 is an overall configuration diagram of the solenoid valve 100 in the embodiment of the present invention. Note that Fig. 1 shows the state of the solenoid valve 100 when it is not energized.

[0019] The solenoid valve 100 includes a solenoid 102 and a plunger 104 shown in Fig. 1, and the plunger 104 is displaced by the attractive force generated when the solenoid 104 is energized to switch the flow path. The body 106 of the solenoid valve 100 has one supply port 108 and two discharge ports 110 and 112 arranged on both sides of the supply port 108. Thereby, the solenoid valve 100 functions as a three-way valve.

[0020] Furthermore, the solenoid valve 100 includes a valve body 114, a pin 116, a stopper 118, a relay spring 120, a return spring 122, and a control circuit 124 that controls the current applied to the solenoid 102. Inside the body 106, a first valve seat 126 and a second valve seat 128 are formed. The first valve seat 126 is formed between the supply port 108 and the discharge port 110 and is the drive side for the solenoid 102 within the body 106. The second valve seat 128 is formed between the supply port 108 and the discharge port 112 and is the return side for the return spring 122.

[0021] The valve body 114 is movably positioned inside the body 106 between the first valve seat 126 and the second valve seat 128, and seats on either the first valve seat 126 or the second valve seat 128. The valve body 114 also has a bottomed shaft hole 114a that extends axially for the pin 116. The tip 116c of the pin is movably clearance fitted into the shaft hole 114a of the valve body 114.

[0022] The plunger 104 shown in Figure 1 is a movable iron core and is integrally configured with the pin 116. The plunger 104 moves together with the pin 116 within the case 130 toward the first valve seat 126 due to the attractive force generated when the solenoid 102 is energized. In other words, the solenoid 102 moves the plunger 104 and the pin 116 toward the first valve seat 126.

[0023] The stopper 118 is a fixed core, located between the plunger 104 and the valve body 114, and positioned at one end of the stroke (magnetic gap) of the plunger 104. The intermediate spring 120 is attached to the pin 116 (see Figure 3(c)) and functions as a damper (suspension) by biasing the valve body 114 toward the first valve seat 126 when the solenoid 102 is energized (described later). It is also preferable that the initial load of the intermediate spring 120 is greater than the compressive load of the return spring 122.

[0024] The return spring 122 shown in Figure 1 biases the valve body 114 toward the second valve seat 128 with a biasing force Fa indicated by the arrow in the figure (in other words, the return spring 122 biases the valve body 114 toward the direction away from the first valve seat 126). As a result, when the solenoid 102 is not energized, the valve body 114 of the solenoid valve 100 is seated on the second valve seat 128 by the biasing force Fa of the return spring 122. Then the second valve seat 128, on which the valve body 114 is seated, closes, and the first valve seat 126 opens.

[0025] Therefore, the solenoid valve 100 has an open space between the supply port 108 and the discharge port 110, ensuring a flow path, and the fluid supplied from the supply port 108 (see arrow B in Figure 2(a)) is discharged from the discharge port 110 through the first valve seat 126 (see arrow A in Figure 2(a)).

[0026] The operation of the solenoid valve 100 will be explained below with reference to Figures 2-6. Figure 2 is a diagram illustrating the operation of the solenoid valve 100 shown in Figure 1. Note that Figure 2(a) is a reproduction of Figure 1.

[0027] Figure 2(a) shows the state when the solenoid 102 is not energized, with the first valve seat 126 open and the second valve seat 128 closed. Figure 3 is a diagram showing the main parts of the solenoid valve in Figure 2(a), and Figure 3(a) is a reproduction of Figure 2(a) for simplicity. Figure 3(b) is an enlarged view of the vicinity of the plunger 104, and Figure 3(c) is an enlarged view of the vicinity of the relay spring 120.

[0028] As shown in Figure 3(b), when de-energized, the plunger 104 is biased by the return spring 122 and returns to its rightmost position in the figure. At this time, a magnetic gap G of dimension La is formed between the plunger 104 and the stopper 118.

[0029] As shown in Figure 3(c), the pin 116 has a notch 116a and a step 116b. A first spring stopper 132 is mounted in the notch 116a of the pin 116 so as to be movable in the axial direction of the pin 116. The first spring stopper 132 faces the end face 114b of the valve body 114 and also abuts against one end 120a of the relay spring 120.

[0030] A second spring stopper 134 is attached to the step 116b of the pin 116. The second spring stopper 134 abuts against the other end 120b of the intermediate spring 120, thereby positioning the intermediate spring 120 relative to the pin 116.

[0031] As shown in Figure 3(c), there is a free travel distance D between the end face 114b of the valve body 114 and the first spring stopper 132 attached to the notch 116a of the pin 116, and the two are not in contact.

[0032] Figure 2(b) shows the state just before the second valve seat 128 opens when current is applied to the solenoid 102. Figure 4 shows the main parts of the solenoid valve 100 in Figure 2(b), and Figure 4(a) is a reproduction of Figure 2(b) for simplicity. Figure 4(b) is an enlarged view of the vicinity of the plunger 104, and Figure 4(c) is an enlarged view of the vicinity of the relay spring 120.

[0033] In the solenoid valve 100, the solenoid 102 generates an attractive force when energized, and this attractive force causes the plunger 104 and pin 116 to move toward the first valve seat 126. Therefore, just before the second valve seat 128 opens, as shown in Figures 2(b) and 4(a), the plunger 104 moves slightly toward the first valve seat 126. As shown in Figure 4(b), when the plunger 104 has moved the same distance as the free travel distance D, it comes into contact with the end face 114b of the valve body 114, as shown in Figure 4(c), and the free travel distance D becomes zero. Let Lb be the dimension of the magnetic gap G at this time.

[0034] Figure 2(c) shows the state immediately after the second valve seat 128 opens and the first valve seat 126 closes, following the state shown in Figure 2(b). Figure 5 shows the main parts of the solenoid valve 100 in Figure 2(c), and Figure 5(a) is a reproduction of Figure 2(c) for simplicity. Figure 5(b) is an enlarged view of the vicinity of the plunger 104, and Figure 5(c) is an enlarged view of the vicinity of the relay spring 120.

[0035] As shown in Figure 5(c), the first spring stopper 132 is in contact with the end face 114b of the valve body 114, and the free travel distance D is zero. The plunger 104 moves further toward the first valve seat 126 due to the suction force.

[0036] Therefore, the pin 116 indirectly pushes and moves the valve body 114 toward the first valve seat 126 via the intermediate spring 120 and the first spring stopper 132. At this time, as shown in Figure 5(a), the pin 116 moves toward the first valve seat 126 together with the plunger 104 by an attractive force Fc, against the combined elastic force of the biasing force Fa of the return spring 122 and the biasing force Fb of the intermediate spring 120.

[0037] If Lc is the dimension of the magnetic gap G when the valve body 114 is seated on the first valve seat 126, then the plunger 104 has advanced by Lb-Lc. Then the first valve seat 126, on which the valve body 114 is seated, closes, and the second valve seat 128 opens. As a result, the solenoid valve 100 opens between the supply port 108 and the discharge port 112, ensuring a flow path, and the fluid supplied from the supply port 108 (see arrow B) passes through the second valve seat 128 and is discharged from the discharge port 112 (see arrow C).

[0038] Furthermore, while the valve body 114 moves from the second valve seat 128 toward the first valve seat 126 and sits down, the return spring 122, which has a smaller load than the intermediate spring 120, is mainly compressed. As a result, in the solenoid valve 100, the valve body 114 can be seated more quickly on the first seat 126 compared to when the intermediate spring 120 is mainly compressed, thereby improving the responsiveness of the valve body 114.

[0039] In the solenoid valve 100 shown in Figures 2(c) and 5(a), the return spring 122 is not compressed further when the valve body 114 is seated on the first valve seat 126. As shown in Figure 5(c), the length of the intermediate spring 120 when the valve body 114 is in contact with the first valve seat 126 is denoted as dimension Sa.

[0040] Figure 2(d) shows the state in which the solenoid 102 is energized, following Figure 2(c). Figure 6 shows the main parts of the solenoid valve 100 in Figure 2(d), and Figure 6(a) is a reproduction of Figure 2(d) for simplicity. Figure 6(b) is an enlarged view of the vicinity of the plunger 104, and Figure 6(c) is an enlarged view of the vicinity of the relay spring 120.

[0041] In the solenoid valve 100, the pin 116 is movable through the shaft hole 114a of the valve body 114, and biases the valve body 114 toward the first valve seat 126 via the intermediate spring 120. Therefore, the intermediate spring 120 functions as a suspension. That is, even when the valve body 114 is seated on the first valve seat 126 and cannot move any further, the intermediate spring 120 is compressed by the attractive force Fc of the solenoid 102, and the plunger 104 can move further. If the length of the intermediate spring 120 shown in Figure 6(c) is dimension Sb, it is shorter than the dimension Sa shown in Figure 5(c).

[0042] As shown in Figure 6(c), when the relay spring 120 is compressed, the second spring stopper 134 on the right side of the figure moves toward the first valve seat 126 together with the pin 116. The first spring stopper 132 on the left side does not move because it is in contact with the valve body 114, but moves toward the right side of the figure relative to the pin 116 within the notch 116a. As a result, the tip 116c of the pin is inserted into the shaft hole 114a of the valve body 114 by the dimension Lc of the magnetic gap G shown in Figure 5(b).

[0043] As a result, as shown in Figure 6(b), the plunger 104 comes into contact with the stopper 118, the magnetic gap G is absorbed, its dimension Ld (see Figure 6(a)) becomes zero, and the plunger 104 and the stopper 118 come into close contact. The intermediate spring 120 functions as a suspension by appropriately setting its length and the position in which it is attached to the pin 116 so that it does not become fully compressed before the valve body 114 seats on the first valve seat 126.

[0044] When the magnetic gap G becomes zero, the attractive force Fc of the solenoid 102 increases dramatically. The attractive force Fc decreases inversely proportional to the square of the distance between the plunger 104 and the stopper 118. Therefore, in the solenoid valve 100, sufficient holding force can be obtained even if the control circuit 124 reduces the current required to maintain the state in which the valve body 114 is seated on the first valve seat 126 (the holding current applied to the solenoid 102) (see Figure 7).

[0045] Figure 7 is a graph showing the characteristics of the solenoid valve 100 in an embodiment of the present invention. In the figure, the vertical axis represents the suction force Fc of the solenoid 102, and the horizontal axis represents the stroke of the plunger 104. The suction force Fc of the solenoid 102 is the suction force generated between the plunger 104 and the stopper 118, and is the force that pushes the pin 116.

[0046] Furthermore, on the horizontal axis, Xa indicates the position when the valve body 114 is seated on the second valve seat 128 when de-energized. Xb indicates the position when the valve body 114 is seated on the first valve seat 126 when energized. Xc indicates the position when the pin 116 is inserted into the axial hole 114a of the valve body 114 and the magnetic gap G is absorbed.

[0047] As shown in graph H, the combined elastic force of the biasing force Fa of the return spring 122 and the biasing force Fb of the intermediate spring 120 increases while the valve body 114 moves from the second valve seat 128 to the first valve seat 126 (from Xa to Xb). Here, the combined elastic force at Xb is denoted as P.

[0048] Furthermore, as shown in graph H, after the valve body 114 seats on the first valve seat 126, the return spring 122 is not compressed any further while the magnetic gap G is absorbed (from Xb to Xc), so the intermediate spring 120 is compressed by dimension Lc. Here, at Xc, the elastic force Q is defined as the sum of the combined elastic force P and the biasing force Fb of the intermediate spring 120.

[0049] In the conventional technology (configuration without the intermediate spring 120), the plunger 104 can only move up to Xb. The difference between the suction force Fc and the composite elastic force P at this time is defined as the excess suction force α (equivalent to the holding force of the plunger in the conventional technology).

[0050] Furthermore, in the solenoid valve 100, even after the valve body 114 has seated on the first valve seat 126, the relay spring 120 can be compressed by dimension Lc to absorb the magnetic gap G. When the magnetic gap G is absorbed (Xc), the attractive force Fc increases dramatically. If the difference between the attractive force Fc and the elastic force Q at this time is called the excess attractive force β, then in the solenoid valve 100, an excess attractive force β can be obtained that is dramatically larger than the excess attractive force α. As a result, as described above, even if the holding current applied to the solenoid 102 is reduced by the control circuit 124, sufficient holding force can be obtained. Also, in the solenoid valve 100, the valve body 114 can be brought into close contact with the first valve seat 126 by the biasing force Fb of the relay spring 120 rather than by a large excess attractive force β, thus extending the lifespan of the first valve seat 126 and the valve body 114.

[0051] As described above, in the solenoid valve 100 according to this embodiment, the pin 116 indirectly pushes and moves the valve body 114 via the relay spring 120. After the valve body 114 is seated on the first valve seat 126, the plunger 104 moves while compressing the relay spring 120, and the pin 116 is inserted into the shaft hole 114a of the valve body 114. As a result, the plunger 104 can move until it contacts the stopper 118, which is a fixed iron core (until the magnetic gap G becomes zero). This increases the attractive force Fc against the current, so that the current required to maintain the position of the plunger 104 can be reduced, and the state in which the valve body 114 is seated on the first valve seat 126 can be maintained with low power consumption.

[0052] Although the solenoid valve 100 described above is a three-way valve, it is not limited to this and may be a two-way valve with one supply port and one discharge port. Also, although there is one relay spring 120, multiple springs may be provided as long as they can indirectly bias the valve body 114 toward the first valve seat 126. The valve body 114 may also be a poppet valve or a ball valve. Furthermore, the supply port 108 may be used as a discharge port, and the discharge ports 110 and 112 may be used as supply ports. In addition, the solenoid valve 100, which is a three-way valve, may be used as a two-way valve by closing one of the discharge ports 110 and 112 with a plug.

[0053] Figure 8 shows an embodiment in which one discharge port is blocked to create a two-way valve. The solenoid valve 100A shown in Figure 9 has the discharge port 112 sealed by a plug 140. As a result, the solenoid valve 100A functions as a two-way valve that opens and closes the connection between the supply port 108 and the discharge port 110.

[0054] Even with the above configuration, the plunger 104 moves while compressing the relay spring 120 after the valve body 114 has seated on the first valve seat 126, and the pin 116 is inserted into the shaft hole 114a of the valve body 114. As a result, the current required to maintain the position of the plunger 104 can be reduced, and the state in which the valve body 114 is seated on the first valve seat 126 can be maintained with low power consumption.

[0055] Furthermore, the parts for three-way valves and two-way valves can be standardized, reducing the burden on production lines and inventory management.

[0056] Figure 9 shows an embodiment in which the discharge port is reduced to one and a two-way valve is formed. The solenoid valve 200 shown in Figure 9 does not have a discharge port 112 and does not have a second valve seat 128. In other words, the solenoid valve 200 has only a first valve seat 126 formed inside the body 106. The remaining configuration is the same as that of the solenoid valve 100 described using Figure 1.

[0057] Even with the above configuration, the plunger 104 moves while compressing the relay spring 120 after the valve body 114 has seated on the first valve seat 126, and the pin 116 is inserted into the shaft hole 114a of the valve body 114. As a result, the current required to maintain the position of the plunger 104 can be reduced, and the state in which the valve body 114 is seated on the first valve seat 126 can be maintained with low power consumption.

[0058] Preferred embodiments of the present invention have been described above with reference to the attached drawings, but it goes without saying that the present invention is not limited to these examples. It will be obvious to those skilled in the art that various modifications or alterations can be conceived within the scope of the claims, and these will naturally also fall within the technical scope of the present invention. [Industrial applicability]

[0059] The present invention can be used as a solenoid valve comprising a solenoid and a plunger, and as a control method for the same. [Explanation of Symbols]

[0060] 100, 100A, 200… Solenoid valve, 102… Solenoid, 104… Plunger, 106… Body, 108… Supply port, 110, 112… Discharge port, 114… Valve body, 114a… Shaft hole of valve body, 114b… End face of valve body, 116… Pin, 116a… Notch of pin, 116b… Step of pin, 116c… Tip of pin, 118… Stopper, 120… Relay spring, 120a… One end of relay spring, 120b… Other end of relay spring, 122… Return spring, 124… Control circuit, 126… First valve seat, 128… Second valve seat, 130… Case, 132… First spring stopper, 134… Second spring stopper, 140… Plug

Claims

1. A valve seat formed inside the body, A valve body seated on the valve seat, A pin is movably fitted into a axial hole formed in the valve body, A plunger that moves integrally with the aforementioned pin, A stopper, which is a fixed iron core located between the plunger and the valve body and positioned at one end of the plunger's stroke, A solenoid that moves the plunger and the pin toward the valve seat, A relay spring attached to the pin and biasing the valve body toward the valve seat, The valve body is biased in a direction away from the valve seat by a return spring, The solenoid valve is characterized in that the pin is movable even after the valve body has seated on the valve seat when the solenoid is energized, until the plunger comes into contact with the stopper.

2. A body having one supply port and two discharge ports located on either side of the supply port, A first valve seat and a second valve seat are formed inside the body between the supply port and each of the two discharge ports, A valve body is movably disposed within the body between the first valve seat and the second valve seat, and seats on the first valve seat or the second valve seat. A pin is movably fitted into a axial hole formed in the valve body, A plunger that moves integrally with the aforementioned pin, A stopper, which is a fixed iron core located between the plunger and the valve body and positioned at one end of the plunger's stroke, A solenoid that moves the plunger and the pin toward the first valve seat, A relay spring attached to the pin and biasing the valve body toward the first valve seat, The valve body is provided with a return spring that biases it toward the second valve seat, The solenoid valve is characterized in that the pin is movable even after the valve body has seated on the first valve seat when the solenoid is energized, until the plunger comes into contact with the stopper.

3. The solenoid valve according to claim 1 or 2, characterized in that the initial load of the relay spring is greater than the compressive load of the return spring.

4. A method for controlling a solenoid valve, characterized by using the solenoid valve according to any one of claims 1 to 3, and reducing the current applied to the solenoid after the plunger contacts the stopper.

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