Solenoid valve

Abstract

A solenoid valve 1 comprises: an electromagnetic coil 11; a plunger 17 that is operated by a magnetic field which is generated when a current is supplied to the electromagnetic coil 11; a valve part 20 that is connected to the plunger 17 and of which the valve opening / closing degree to a flow passage is adjusted according to the operation of the plunger 17; and an electrical adjustment unit 30 that has a plurality of resistance elements, and switch units for resistance switching that are provided so as to correspond respectively to the resistance elements and that switch between combinations of the resistance element, the electrical adjustment unit adjusting a current supplied to the electromagnetic coil 11.

Description

solenoid valve

[0001] The present invention relates to a solenoid valve.

[0002] Solenoid valves are widely used in devices that require fluid flow control. A solenoid valve is a proportional control valve that adjusts the opening and closing degree of the valve by operating a plunger connected to a valve body depending on the amount of power supplied to a coil.

[0003] The plunger stroke characteristics of individual solenoid valves can vary, so adjustments must be made to reduce the variation in stroke characteristics between individual valves.

[0004] For example, Patent Document 1 discloses a solenoid valve that mechanically adjusts the stroke. Patent Document 1 states that "the solenoid valve is composed of a solenoid unit (10) and a valve unit (20), the valve unit (20) is composed of a valve body (21), a guide (22), and a valve seat body (24), the valve seat body (24) and an insertion hole (25) of the valve body are threadedly engaged with a threaded portion, and the valve seat body (24) has a hollow cylindrical shape and is provided with a valve seat (24a) against which the movable iron core (11) abuts, and an operating protrusion (24b) on the outer surface of which is provided with a non-slip surface on the circumferential surface."

[0005] Furthermore, Patent Document 1 states that "the operating protrusion (24b) is disposed in a groove (28) cut into the upper surface of the valve body (21), and since the groove (28) is cut out to the side surface of the valve body (21), the operating protrusion (24b) appears to the outside through a window (29) and can move up and down by the height of the window (29). When the operating protrusion (24b) is rotated, the valve seat body (24) threaded into the insertion hole (25) is threaded up and down, and the distance between the valve seat (24a) and the movable iron core (11) can be adjusted, so that the stroke can be adjusted mechanically."

[0006] Patent Document 2 discloses an electromagnetic safety valve in which the force required to open the valve can be adjusted by adjusting the force of a closing spring, which is interposed between a fixed core and a plunger and elastically presses the plunger in the direction of pressing the valve body against the valve seat, by expanding or contracting the spring force.

[0007] Japanese Unexamined Patent Publication No. 10-281327 Publication of Utility Model Application No. 58-35053

[0008] In Patent Document 1, the stroke can be adjusted mechanically, and in Patent Document 2, the force required to open the valve can be adjusted by adjusting the spring force. However, adjusting the stroke characteristics by combining these methods results in problems such as the valve itself becoming larger, which requires time and effort for adjustment. Another problem is that the valve must be stopped during adjustment.

[0009] SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a solenoid valve that can easily adjust for individual differences in the stroke characteristics of the plunger of the solenoid valve without shutting down the device.

[0010] A solenoid valve according to a representative embodiment of the present invention comprises an electromagnetic coil, a plunger that operates due to a magnetic field generated when current is supplied to the electromagnetic coil, a valve section connected to the plunger and adjusting the valve opening / closing degree for the flow path in accordance with the operation of the plunger, and an electrical adjustment section that has a plurality of resistance elements and resistance switching switch sections that are provided corresponding to each of the resistance elements and switch the combination of the resistance elements, and that adjusts the current supplied to the electromagnetic coil.

[0011] According to the present invention, it is possible to easily adjust for individual differences in the stroke characteristics of the plunger of the solenoid valve without stopping the device.

[0012] FIG. 1 is a block diagram illustrating the configuration of a solenoid valve according to a first embodiment of the present invention. FIG. 2 is a schematic cross-sectional view illustrating the configuration of a solenoid valve. FIG. 3 is a circuit diagram according to a first embodiment of the present invention. FIG. 4 is a diagram illustrating an example of a combination of resistance elements. FIG. 5 is a circuit diagram when each resistance element of an electrical adjustment unit is connected in parallel to an electromagnetic coil. FIG. 6 is a circuit diagram when a variable resistor is used in the electrical adjustment unit. FIG. 7 is a diagram explaining the relationship between a current supplied from an external power supply and a flow rate of a fluid. FIG. 8 is a diagram explaining a method of adjusting stroke characteristics. FIG. 9 is a circuit diagram according to a second embodiment of the present invention. FIG. 10 is a diagram explaining a method of adjusting stroke characteristics. FIG. 11 is a block diagram illustrating the configuration of a solenoid valve according to a third embodiment of the present invention.

[0013] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In each drawing for explaining the embodiment, the same components are generally designated by the same reference numerals, and repeated description thereof will be omitted as appropriate.

[0014] <Configuration of solenoid valve> <<Solenoid section>> Fig. 1 is a block diagram illustrating the configuration of a solenoid valve according to a first embodiment of the present invention. Fig. 2 is a schematic cross-sectional view illustrating the configuration of the solenoid valve. As shown in Fig. 1, the solenoid valve 1 includes a solenoid section 10, a valve section 20, and an electrical adjustment section 30.

[0015] 1 and 2, the solenoid unit 10 includes an electromagnetic coil 11, an internal coil core 13, a casing 15, and a plunger 17. Of these, the electromagnetic coil 11 and the internal coil core 13 are fixed within the casing 15.

[0016] The electromagnetic coil 11 is a solenoid coil in which a conductor is wound around the coil core 13 and the internal space 19. The electromagnetic coil 11 generates a magnetic field by a current supplied from an external power source. This causes the electromagnetic coil 11 to magnetize the plunger 17 and pull it into the internal space 19.

[0017] The coil core 13 is disposed on the opposite side of the plunger 17 and the internal space 19 from the valve portion 20. The coil core 13 is an element that increases the inductance of the magnetic field generated by the electromagnetic coil 11.

[0018] The plunger 17 is disposed with at least a portion inserted into the internal space 19, with an air gap provided between it and the coil core 13. The plunger 17 disposed in the internal space 19 has one end facing the coil core 13 and the other end connected to a valve body 21 of the valve section 20. The plunger 17 is movable within the internal space 19 along the extension direction of the electromagnetic coil 11 (the up-and-down direction in FIG. 2 ). As a result, the plunger 17 is subjected to a magnetic force due to a magnetic field generated when a current is supplied to the electromagnetic coil 11, and moves within the internal space 19.

[0019] <<Valve Unit>> The valve unit 20 is a functional block that adjusts the opening and closing degree of the valve for the flow path 51 provided in the body 50 in accordance with the operation of the plunger 17. As shown in Figure 2, the valve unit 20 includes a valve element 21, a valve seat 23, a spring 25, and a valve unit cover 27. The valve element 21, the valve seat 23, and the spring 25 are housed in the valve unit cover 27.

[0020] The valve body 21 is configured by combining a columnar portion 21A (e.g., a cylinder or a rectangular pillar) connected to the other end of the plunger 17 and a contact portion 21B (e.g., a truncated cone or pyramid, or may be a cylinder or a rectangular pillar like the columnar portion 21A) on the valve seat 23 side. A spring 25 supported by the valve portion cover 27 is provided near the boundary between the columnar portion 21A and the contact portion 21B. The spring 25 applies a biasing force to the contact portion 21B toward the valve seat 23 side.

[0021] The valve seat 23 is disposed so as to surround the opening of the flow path 51A (51) exposed on the surface 50A of the body 50. The valve seat 23 functions as a support for the valve element 21. In the open valve state, the valve seat 23 is spaced apart from the valve element 21. On the other hand, in the closed valve state, the valve seat 23 is pressed by the abutment portion 21B of the valve element 21.

[0022] <<<Operation of Solenoid Valve>>> Here, the operation of the solenoid valve 1 will be described. When no current flows through the electromagnetic coil 11, no magnetic field is generated by the electromagnetic coil 11, and therefore no magnetic force is applied to the plunger 17. As a result, the valve body 21 is pressed against the valve seat 23 by the biasing force of the spring 25. This blocks the opening of the flow path 51A, resulting in a valve-closed state, and the flow of fluid between the flow path 51A and the flow path 51B (51B) is blocked.

[0023] In contrast, when current is supplied to the electromagnetic coil 11, a magnetic field is formed that passes through the internal space 19, the internal coil core 13, the casing 15, and back into the internal space 19. This magnetic field magnetizes the internal coil core 13 and the plunger 17. When the magnetic force acting on the plunger 17 becomes greater than the biasing force of the spring 25, the plunger 17 moves in the internal space 19 toward the internal coil core 13. This causes the valve body 21 to move away from the valve seat 23, resulting in an open valve state, where the flow paths 51A and 51B are connected, allowing fluid to flow between the flow paths 51A and 51B.

[0024] <<Electrical Adjustment Unit>> In this embodiment, the electrical adjustment unit 30 is a functional block that is connected in parallel to the electromagnetic coil 11 and adjusts the current supplied to the electromagnetic coil 11. By adjusting the current supplied to the electromagnetic coil 11, it is possible to adjust the stroke characteristics of the plunger 17. Here, the stroke characteristics include, for example, the timing at which the valve opens when a certain current is applied and the stroke amount of the plunger 17 at that time.

[0025] By adjusting the stroke characteristics, it becomes possible to appropriately adjust the flow rate of the fluid. Furthermore, by suppressing the variation in stroke characteristics between products, it becomes possible to appropriately control the flow rate of the fluid in each flow path when multiple solenoid valves are used.

[0026] FIG. 3 is a circuit diagram according to the first embodiment of the present invention. As shown in FIG. 3, in this embodiment, the electromagnetic coil 11 and the electrical adjustment unit 30 are connected in parallel. Therefore, assuming that the value of the current flowing through the circuit is constant, as the resistance value of the electrical adjustment unit 30 increases, the current flowing through the electrical adjustment unit 30 decreases, and the current supplied to the electromagnetic coil 11 increases. This increases the magnetic force applied to the plunger 17. In contrast, as the resistance value of the electrical adjustment unit 30 decreases, the current flowing through the electrical adjustment unit 30 increases, and the current supplied to the electromagnetic coil 11 decreases. This decreases the magnetic force applied to the plunger 17.

[0027] In this way, in this embodiment, the current supplied to the electromagnetic coil 11 can be adjusted by switching the resistance value of the electrical adjustment unit 30 and controlling the current diverted to the electrical adjustment unit 30.

[0028] As shown in FIG. 3 , the electrical adjustment unit 30 includes a plurality of resistance elements (e.g., Ra-Rd), resistance switching switches (first switches; e.g., SWa-SWd) provided corresponding to the respective resistance elements to switch the combination of the resistance elements, and a switch (second switch) SWm to switch the electrical adjustment unit 30 on and off. The plurality of resistance elements Ra-Rd in the electrical adjustment unit 30 are connected in series. The electrical adjustment unit 30 may be configured such that the resistance elements are connected in parallel, or may be configured such that a portion of the resistance elements connected in parallel is combined with a portion of the resistance elements connected in series. The number of resistance elements is not limited to this example and may be three or less (including one), or five or more.

[0029] Each switch can be manually turned on and off. In this case, the solenoid valve body is not touched, so it can be operated without stopping the solenoid valve.

[0030] The resistance value of each resistive element may be selected according to the resistance value of the electromagnetic coil 11, and may be set to, for example, a value several times to several hundred times the resistance value of the electromagnetic coil. Furthermore, the adjustment range (current adjustment range) of the current supplied to the electromagnetic coil 11 may be set, and the resistance value of each resistive element may be set so as to cover the range from the lower limit to the upper limit of the current adjustment range.

[0031] When the switch SWm is off, no current flows through the electrical adjustment unit 30, and all of the current supplied from the external power supply is supplied to the electromagnetic coil. Therefore, current adjustment is performed when the switch SWm is on.

[0032] The electrical adjustment unit 30 is configured to be able to switch the resistance within the electrical adjustment unit 30 by switching on / off the switch units SWa-SWd provided in each of the resistance elements Ra-Rd. For example, when a certain switch unit is off, the path via the switch unit is blocked, and the resistance value of the electrical adjustment unit 30 increases by the amount of this resistance element.

[0033] On the other hand, when a switch section is on, there is a current path that passes through this switch section. As a result, this section forms a parallel circuit with the switch section and the corresponding resistive element, and the resistance value is the combined resistance value of the switch section and the resistive element. However, since the resistance value of the switch section is much smaller than that of the resistive element, the resistance value of this section is almost the same as the resistance value of the switch section. In other words, although a parallel circuit is formed with the switch section and the corresponding resistive element, most of the current flows through the switch section, and almost no current flows through the resistive element. In this way, the resistive element becomes almost non-functional, so there is no need to take the resistance value of the resistive element into consideration.

[0034] Fig. 4 is a diagram showing an example of a combination of resistor elements. Fig. 4 shows the combination of resistor elements when four resistor elements with resistance values ​​of R, 2.2R, 4.7R, and 10R are used, and the combined resistance value of the electrical adjustment unit 30. Note that "R" in Fig. 4 indicates the smallest resistance value among these resistor elements.

[0035] In Fig. 4, when "1" is written, the switch is off and current flows through the resistor element, so the resistance value of that resistor element is added to the combined resistance value. In contrast, when "0" is written, the switch is on and almost no current flows through the resistor element, so the resistance value of the resistor element does not need to be taken into account. In the example of Fig. 4, the combined resistance value of the electrical adjustment unit 30 can be adjusted in stages from 0 to 17.9R.

[0036] 5 is a circuit diagram in which each resistance element of the electrical adjustment unit is connected in parallel to the electromagnetic coil. Each resistance element Ra-Rd, together with a corresponding switch unit SWa-SWd, constitutes a resistance element block BLa-BLd. In each resistance element block BLa-BLd, the resistance element Ra-Rd and the corresponding switch unit SWa-SWd are connected in series. Multiple resistance element blocks BLa-BLd are connected in parallel.

[0037] In this case, compared to when the resistance elements Ra-Rd are connected in series, the current flowing through each resistance element is smaller, allowing the size of the resistance elements used to be reduced. Furthermore, even if the switch unit SWm that switches the electrical adjustment unit 30 on and off is not provided, all current supplied from the external power source can be supplied to the electromagnetic coil by turning off the switches SWa-SWd that are connected in series to each resistance element, making the switch unit SWm unnecessary. This makes it possible to further reduce the size of the electrical adjustment unit 30, and ultimately the solenoid valve. The configuration of the electrical adjustment unit 30 shown in FIG. 5 can also be applied to the following embodiments.

[0038] Fig. 6 is a circuit diagram when a variable resistor is used in the electrical adjustment unit. As shown in Fig. 6, the electrical adjustment unit 30 may include a variable resistor Rch instead of the resistance element in Fig. 3. By including a variable resistor, it becomes possible to precisely adjust the resistance value of the electrical adjustment unit 30.

[0039] <Relationship Between Current Supplied from External Power Supply and Fluid Flow Rate> Here, the relationship between the current supplied from the external power supply (hereinafter also referred to as power supply current) and the fluid flow rate will be described. FIG. 7 is a diagram illustrating the relationship between the current supplied from the external power supply and the fluid flow rate. In FIG. 7, the horizontal axis represents the current supplied from the external power supply, and the vertical axis represents the fluid flow rate. FIG. 7 also shows a graph of the relationship between the current supplied from the external power supply and the fluid flow rate when the resistance value of the electrical adjustment unit 30 is set to Rt1-Rt5 (Rt1<Rt2<Rt3<Rt4<Rt5).

[0040] As shown in Figure 7, when the current supplied from the external power supply is small, the valve remains closed and no fluid flows. When the current supplied from the external power supply increases, the valve opens and fluid begins to flow. The power supply current when fluid begins to flow is called the lift-off current. When the current supplied from the external power supply increases further, the flow rate of the fluid increases further.

[0041] 7, when the resistance value of the electrical adjustment unit 30 is large, the current supplied to the electromagnetic coil 11 is larger than when the resistance value is small, and therefore the fluid starts to flow even with a small power supply current. Therefore, when the resistance value of the power supply adjustment unit 30 is large, the lift-off current is small, and when the resistance value of the power supply adjustment unit 30 is small, the lift-off current is large.

[0042] <Method of Adjusting Stroke Characteristics> Next, a method of adjusting stroke characteristics will be described. FIG. 8 is a diagram illustrating a method of adjusting stroke characteristics. In FIG. 8, the horizontal axis represents the resistance value of the electrical adjustment unit 30, and the vertical axis represents the lift-off current. Note that the resistance value Rs on the horizontal axis is set for convenience of explanation. FIG. 8 also shows a graph of the relationship between the resistance value of the electrical adjustment unit 30 and the lift-off current for each of the three solenoid valves (1), (2), and (3).

[0043] As shown in FIG. 8 , when the resistance values ​​of the electrical adjustment units 30 are the same, the lift-off current is largest for solenoid valve (1), followed by solenoid valve (2) and solenoid valve (3) in that order. This accounts for individual product differences (manufacturing variations). For example, if it is desired to set the lift-off current of each solenoid valve (1)-(3) to a predetermined current (set lift-off current) Is, referring to FIG. 8 , the resistance value of solenoid valve (1) should be adjusted to approximately 1.5 Rs, the resistance value of solenoid valve (2) to approximately 0.9 Rs, and the resistance value of solenoid valve (3) to approximately 0.6 Rs. Setting the resistance values ​​of each solenoid valve (1)-(3) in this manner reduces variations in stroke characteristics between products.

[0044] Specifically, the manufacturing process involves first operating the switch unit so that the electrical adjustment unit 30 has a predetermined resistance value, and gradually increasing the voltage (applied voltage) from the external power supply. Then, the applied voltage and current (lift-off current) are measured the instant the fluid starts to flow. These operations are repeated while switching the resistance value. Once all operations for one product are complete, similar operations are performed for the other solenoid valves that are being adjusted for manufacturing variations. Once operations for all products are complete, the resistance value of the electrical adjustment unit 30 for each product is adjusted based on the measurement data, as described above, so that the lift-off current reaches a predetermined value.

[0045] <Major Effects of the Present Embodiment> This embodiment is provided with an electrical adjustment unit 30 that adjusts the current supplied to the coil. With this configuration, there is no need to make adjustments directly to the valve body, and there is no need to stop the device. Furthermore, because the adjustment itself does not require time or effort, it is possible to easily adjust the stroke characteristics of the plunger 17 without stopping the device. By adjusting for individual differences in stroke characteristics, it is possible to adjust the current at which the solenoid valve begins to open (lift-off current), which reduces variations in the magnetic characteristics, etc., of each solenoid valve and makes it easy to keep the timing at which the fluid starts to flow consistent between devices.

[0046] This also ensures that the current when the valve is open is constant, so that the current value when controlling a specific flow rate falls within a predetermined range, reducing variations between products. Also, variations in responsiveness to control between products are reduced.

[0047] Furthermore, according to this embodiment, the electrical adjustment unit 30 is connected in parallel with the electromagnetic coil 11. With this configuration, the current supplied to the electromagnetic coil 11 can be adjusted by controlling the current diverted to the electrical adjustment unit 30. This allows the stroke characteristics of the plunger 17 to be adjusted.

[0048] The electrical adjustment unit 30 also includes a plurality of resistance elements and a first switch unit for resistance switching, which is connected in parallel with each of the resistance elements. The plurality of resistance elements in the electrical adjustment unit 30 are also connected in series. With this configuration, the resistance value of the electrical adjustment unit 30 can be easily changed by switching on / off the first switch corresponding to each resistance element. This allows the current diverted to the electrical adjustment unit 30 to be controlled, and ultimately the current supplied to the electromagnetic coil 11 to be adjusted.

[0049] Furthermore, according to this embodiment, a second switch unit is provided that switches on / off the electrical adjustment unit 30. With this configuration, the electrical adjustment unit 30 can be stopped when adjustment of the current supplied to the electromagnetic coil 11 is not required. Furthermore, malfunction of the electrical adjustment unit 30 can be prevented.

[0050] (Embodiment 2) Next, embodiment 2 will be described. Fig. 9 is a circuit diagram according to embodiment 2 of the present invention. As shown in Fig. 9, in this embodiment, electromagnetic coil 11 and electrical adjustment unit 30 are connected in series.

[0051] When the resistance value R30 of the electrical adjustment unit 30 decreases, the combined resistance value of the entire circuit (resistance value R11 of the electromagnetic coil 11 + resistance value R30 of the electrical adjustment unit 30) decreases. When the voltage applied to the circuit is constant, the current flowing through the entire circuit increases, and therefore the current supplied to the electromagnetic coil 11 increases. Therefore, the magnetic force applied to the plunger 17 increases. In contrast, when the resistance value of the electrical adjustment unit 30 increases, the combined resistance value of the entire circuit (resistance value R11 of the electromagnetic coil 11 + resistance value R30 of the electrical adjustment unit 30) increases. As a result, the current flowing through the entire circuit decreases, and therefore the current supplied to the electromagnetic coil 11 decreases. Therefore, the magnetic force applied to the plunger 17 decreases.

[0052] In this embodiment in which the electromagnetic coil 11 and the electrical adjustment unit 30 are connected in series, the combined resistance of the entire circuit is adjusted by switching the resistance value R30 of the electrical adjustment unit 30, thereby making it possible to adjust the current supplied to the electromagnetic coil 11. The electrical adjustment unit 30 may be configured such that these resistance elements are connected in parallel, or may be configured such that a portion in which these resistance elements are connected in parallel and a portion in which they are connected in series are combined.

[0053] The circuit configuration of the electrical adjustment unit 30 is the same as that shown in Fig. 3, except for the presence or absence of the switch unit SWm. Also, similar to Fig. 6, the electrical adjustment unit 30 may include a variable resistor Rch instead of the resistance element.

[0054] <Relationship between voltage applied to electromagnetic coil and fluid flow rate> Here, the relationship between the voltage applied to the electromagnetic coil and the fluid flow rate will be explained. When the voltage applied to the electromagnetic coil 11 is small, the valve remains closed and no fluid flows. When the voltage applied to the electromagnetic coil 11 increases, the valve opens and fluid begins to flow. Then, when the voltage applied to the electromagnetic coil 11 increases further, the fluid flow rate increases even further.

[0055] <Stroke characteristic adjustment method> Next, a method for adjusting the stroke characteristics in this embodiment will be described. Fig. 10 is a diagram for explaining the stroke characteristic adjustment method. In Fig. 10, the horizontal axis represents the resistance value R30 of the electrical adjustment unit 30, and the vertical axis represents the lift-off voltage. The power supply voltage when the fluid starts to flow is called the lift-off voltage. Fig. 10 shows a graph of the relationship between the resistance value of the electrical adjustment unit 30 and the lift-off voltage for each of the three solenoid valves (1), (2), and (3).

[0056] As shown in FIG. 10 , when the resistance values ​​of the electrical adjustment units 30 are the same, the lift-off voltage is highest for solenoid valve (1), followed by solenoid valve (2) and solenoid valve (3). This is due to individual product differences. For example, to set the lift-off voltage to a predetermined voltage Vs, the resistance value of the electrical adjustment unit 30 of solenoid valve (1) can be adjusted to R30_1, the resistance value of the electrical adjustment unit 30 of solenoid valve (2) to R30_2 greater than R30_1 (R30_1<R30_2), and the resistance value of the electrical adjustment unit 30 of solenoid valve (3) to R30_3 greater than R30_2 (R30_1<R30_2<R30_3). As a result, the value of the current flowing through each solenoid valve can be adjusted, thereby reducing variations in stroke characteristics between products.

[0057] According to this embodiment, the electrical adjustment unit 30 is connected in series with the electromagnetic coil 11. With this configuration, the current supplied to the electromagnetic coil 11 can be adjusted by the inherent resistance value R11 of the electromagnetic coil 11, the resistance value (combined resistance value) R30 of the electrical adjustment unit 30, and the voltage applied to the circuit. This allows the stroke characteristics of the plunger 17 to be adjusted.

[0058] (Embodiment 3) Next, embodiment 3 will be described. In this embodiment, various sensors are used to automatically adjust the resistance value of the electrical adjustment unit 30. FIG. 11 is a block diagram illustrating the configuration of a solenoid valve according to embodiment 3 of the present invention. The solenoid valve 1 in FIG. 11 has a configuration in which sensors 70 and a controller 90 are added to the configuration in FIG. 1. The sensors 70 include, for example, a current sensor that measures the value of the current supplied from an external power source, a voltage sensor that measures the value of the voltage applied to the electromagnetic coil 11 and the electrical adjustment unit 30, and a flow rate sensor that measures the flow rate of the fluid.

[0059] The controller 90 includes a calculation device that performs various calculations, a memory that temporarily stores programs and various data, a storage device that stores various information, etc. The controller 90 calculates the resistance value to be set for the electrical adjustment unit 30 based on the current and voltage values ​​measured by the sensors 70 and information such as the set lift-off current and set lift-off voltage stored in the storage. The controller 90 then turns on / off the switch units corresponding to the resistance elements in the electrical adjustment unit 30 to adjust the resistance value.

[0060] The on / off information of each switch unit after adjustment can be saved in storage, so that the resistance value of the electrical adjustment unit 30 can be set to the same value as the previous time the next time the device is started.

[0061] According to this embodiment, it is possible to automatically perform the processes from obtaining the current and voltage values ​​in the solenoid valve to adjusting the resistance value of the electrical adjustment unit 30. This reduces the workload involved in adjusting the stroke characteristics.

[0062] Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments. Those skilled in the art can freely change, add, or convert the configurations of the embodiments described above without departing from the spirit of the invention.

[0063] REFERENCE SIGNS LIST 1 solenoid valve 10 solenoid section 11 electromagnetic coil 13 coil core 15 casing 17 plunger 19 internal space 20 valve section 21 valve body 23 valve seat 25 spring 27 valve section cover 30 electrical adjustment section 70 sensors 90 controller

Claims

1. A solenoid valve comprising: an electromagnetic coil; a plunger that operates due to a magnetic field generated when current is supplied to the electromagnetic coil; a valve section connected to the plunger, the valve opening / closing degree for a flow path being adjusted in accordance with the operation of the plunger; and an electrical adjustment section having a plurality of resistance elements and resistance switching switch sections provided corresponding to each of the resistance elements for switching combinations of the plurality of resistance elements, and adjusting the current supplied to the electromagnetic coil.

2. A solenoid valve according to claim 1, wherein the electrical adjustment section is connected in parallel with the electromagnetic coil.

3. A solenoid valve according to claim 1, wherein the electrical adjustment section is connected in series with the electromagnetic coil.

4. A solenoid valve as claimed in claim 1, wherein each of the resistance elements constitutes a resistance element block together with the corresponding switch section, and in each of the resistance element blocks, the resistance element and the corresponding switch section are connected in series, and a plurality of resistance element blocks are connected in parallel.

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