Solenoid valve

Abstract

To provide a solenoid valve capable of suppressing change of a valve opening due to temperature.SOLUTION: A solenoid valve 1 comprises: an electromagnetic coil 11; a plunger 17 that operates due to a magnetic field generated when a current is supplied to the electromagnetic coil 11; a valve unit 20 that is connected to the plunger 17, and adjusts a valve opening relative to a flow path according to the operation of the plunger 17; and an electrical adjustment unit 30 that adjusts the current supplied to the electromagnetic coil 11 using a resistive element whose resistance value varies depending on temperature.SELECTED DRAWING: Figure 1

Description

[Technical field]

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

[0002] Solenoid valves are widely used in devices that require control of the flow rate of a fluid. 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 value of power supplied to a coil.

[0003] For example, Patent Document 1 discloses an example of a solenoid valve. According to Patent Document 1, "A valve body is fixed to the lower end of a plunger that reciprocates relative to a valve seat. A closing spring for pressing the valve body against the valve seat is interposed between the fixed core provided on the upper part of the excitation coil and the plunger, and elastically presses the plunger downward. Therefore, when the excitation coil is not energized, the plunger is lowered by the spring pressure of the closing spring, and the valve body is pressed against the valve seat to close the valve hole. When the excitation coil is energized, the plunger is attracted to open the valve hole and communicate with the outlet." [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Publication No. 58-35053 Summary of the Invention [Problem to be solved by the invention]

[0005] However, as mentioned above, solenoid valves are made up of a combination of various parts, so even if the same power is supplied, the valve opening degree changes due to factors such as temperature changes. For example, if the resistance value of the excitation coil changes, the current flowing through the excitation coil changes, and the magnetic force applied to the plunger changes. This changes the valve opening degree.

[0006] For example, if a resin material is used for the valve body, it will expand / contract with temperature, which will have a large effect on the valve opening. The properties of other materials may also change with temperature, which may affect the valve opening.

[0007] Since the change in the resistance value of the excitation coil is a change in electrical characteristics, it is possible to reduce the effect of this change by, for example, current feedback control. However, other changes are mechanical changes, and therefore cannot be adequately dealt with by current feedback control alone.

[0008] SUMMARY OF THE PRESENT EMBODIMENTS An object of the present invention is to provide a solenoid valve capable of suppressing changes in valve opening caused by temperature. [Means for solving the problem]

[0009] 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 portion connected to the plunger and adjusting the valve opening to the flow path in accordance with the operation of the plunger, and an electrical adjustment portion that adjusts the current supplied to the electromagnetic coil by a resistive element whose resistance value varies with temperature. Effect of the Invention

[0010] According to the present invention, it is possible to suppress changes in valve opening caused by temperature. [Brief description of the drawings]

[0011] [Figure 1] 1 is a block diagram illustrating a configuration of a solenoid valve according to a first embodiment of the present invention. [Diagram 2] 2 is a schematic cross-sectional view illustrating the configuration of a solenoid valve; [Diagram 3] FIG. 4 is a circuit diagram relating to the supply of current to an electromagnetic coil. [Figure 4] FIG. 11 is a circuit diagram according to a second embodiment of the present invention. [Diagram 5] FIG. 11 is a circuit diagram according to a third embodiment of the present invention. [Figure 6] 11 is a circuit diagram in which each resistance element of the electrical adjustment unit is connected in parallel to an electromagnetic coil. FIG. [Figure 7] 11A and 11B are diagrams illustrating a method for adjusting stroke characteristics for the purpose of suppressing variations in stroke characteristics between products. [Figure 8] FIG. 11 is a circuit diagram according to a fourth embodiment of the present invention. [Figure 9] 13A to 13C are diagrams illustrating a method for adjusting stroke characteristics for the purpose of suppressing variations in stroke characteristics between products in a fourth embodiment of the present invention. [Figure 10] FIG. 11 is a block diagram illustrating the configuration of a solenoid valve according to a fifth embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] (Embodiment 1) Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In each drawing for explaining the embodiment, the same members are generally designated by the same reference numerals, and repeated description thereof will be omitted as appropriate.

[0013] <Solenoid valve configuration> <<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 unit 10, a valve unit 20, and an electrical adjustment unit 30.

[0014] 1 and 2, the solenoid unit 10 includes an electromagnetic coil 11, an inner coil core 13, a casing 15, and a plunger 17. Of these, the electromagnetic coil 11 and the inner coil core 13 are fixed within the casing 15.

[0015] The electromagnetic coil 11 is a solenoid coil in which a conductor is wound so as to surround 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.

[0016] The coil core 13 is disposed on the opposite side to the valve portion 20 with respect to the plunger 17 and the internal space 19. The coil core 13 is an element that increases the inductance of the magnetic field generated by the electromagnetic coil 11.

[0017] The plunger 17 is disposed with at least a portion thereof inserted into the internal space 19 while providing an air gap with 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-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.

[0018] <<Valve section>> The valve section 20 is a functional block that adjusts the opening and closing degree of the valve for a flow path 51 provided in a body 50 in response to the operation of the plunger 17. As shown in Fig. 2, the valve section 20 includes a valve body 21, a valve seat 23, a spring 25, and a valve section cover 27. The valve body 21, the valve seat 23, and the spring 25 are housed in the valve section cover 27.

[0019] The valve body 21 is configured by combining a columnar portion 21A (e.g., a cylinder or a rectangular column) connected to the other end of the plunger 17 and an abutment portion 21B (e.g., a truncated cone or pyramid, or may be a cylinder or a rectangular column 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 abutment portion 21B. The spring 25 applies a biasing force to the abutment portion 21B toward the valve seat 23 side.

[0020] The valve seat 23 is disposed so as to surround the opening of the flow passage 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 contact portion 21B of the valve element 21.

[0021] <<<Solenoid valve operation>>> 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 results in a valve-closed state in which the opening of the flow path 51A is blocked, and the flow of fluid between the flow paths 51A and 51B (51) is blocked.

[0022] In contrast, when a current is supplied to the electromagnetic coil 11, a magnetic field is formed that passes through the internal space 19, the coil core 13, the casing 15, and then back to the internal space 19. This magnetic field magnetizes the 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 coil core 13. This causes the valve body 21 to be separated from the valve seat 23, resulting in an open valve state, and the flow paths 51A and 51B to be in communication with each other, allowing fluid to flow between the flow paths 51A and 51B.

[0023] <<Electrical adjustment section>> The electrical adjustment unit 30 in this embodiment is a functional block that is connected in parallel to the electromagnetic coil 11 to adjust the current supplied to the electromagnetic coil 11. By adjusting the current supplied to the electromagnetic coil 11, the stroke of the plunger 17 can be adjusted in response to changes in the valve opening caused by temperature.

[0024] Since the valve opening is adjusted by adjusting the stroke, it is possible to suppress changes in the valve opening caused by temperature, making it possible to appropriately adjust the flow rate of the fluid even when the temperature changes.

[0025] FIG. 3 is a circuit diagram related to the supply of current to the electromagnetic coil. As shown in FIG. 3, in this embodiment, the electromagnetic coil 11 and the electrical adjustment unit 30 are connected in parallel. Therefore, when the value of the current flowing through the circuit is constant, if 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. As a result, the magnetic force applied to the plunger 17 increases, and the valve opening becomes larger. On the other hand, if 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. As a result, the magnetic force applied to the plunger 17 decreases, and the valve opening becomes smaller.

[0026] In this manner, in the present embodiment, the current supplied to the electromagnetic coil 11 can be adjusted by controlling the current diverted to the electrical adjustment unit 30 in accordance with fluctuations in the resistance value of the electrical adjustment unit 30.

[0027] 3, the electrical adjustment unit 30 includes a resistance element Rt. The resistance element Rt is an element whose resistance value varies with temperature. For example, a thermistor such as an NTC (Negative Temperature Coefficient) thermistor, a PTC (Positive Temperature Coefficient) thermistor, or a CTR (Critical Temperature Resistor) thermistor is used as the resistance element Rt.

[0028] NTC thermistors have a negative temperature coefficient, meaning that their resistance decreases gradually as the temperature increases. NTC thermistors are made from materials such as manganese, cobalt, nickel, and iron.

[0029] A PTC thermistor is a thermistor with a positive temperature coefficient, and has the characteristic that its resistance increases rapidly when a certain temperature is exceeded. PTC thermistors are made by doping barium titanate with rare earth elements.

[0030] CTR thermistors are thermistors with a negative temperature coefficient, and have the characteristic that their resistance drops sharply when a certain temperature is exceeded. CTR thermistors are made of ceramics containing vanadium oxide with additives.

[0031] The resistance element Rt may include any one of an NTC thermistor, a PTC thermistor, and a CTR thermistor. If the valve opening becomes smaller as the temperature increases, a thermistor (e.g., a PTC thermistor) whose resistance value increases as the temperature increases is used for the resistance element Rt. This increases the current supplied to the electromagnetic coil 11, and the magnetic force applied to the plunger 17 becomes larger. This allows the valve opening to be increased.

[0032] On the other hand, if the valve opening degree increases as the temperature rises, a thermistor (e.g., an NTC thermistor or a CTR thermistor) whose resistance value decreases as the temperature rises may be used for the resistance element Rt, or a platinum temperature detector may be used. In this case, the current supplied to the electromagnetic coil 11 decreases, and the magnetic force applied to the plunger 17 decreases. This allows the valve opening degree to be reduced.

[0033] <Major Effects of the Present Embodiment> According to this embodiment, an electrical adjustment unit 30 is provided that has a resistance element whose resistance value varies with temperature and adjusts the current supplied to the electromagnetic coil 11. This configuration allows the plunger stroke to be adjusted, so that changes in the valve opening caused by temperature can be suppressed. Furthermore, this configuration does not require the stroke adjustment to be performed directly on the valve body and can be performed without stopping the device, so that the stroke of the plunger 17 can be easily adjusted.

[0034] Moreover, 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 makes it possible to adjust the stroke of the plunger 17.

[0035] According to this embodiment, the resistance element Rt includes one of an NTC thermistor, a PTC thermistor, and a CTR thermistor depending on the change in the valve opening caused by temperature. This configuration allows the use of a thermistor with appropriate characteristics depending on the change in the valve opening caused by temperature.

[0036] (Embodiment 2) Next, a description will be given of embodiment 2. Fig. 4 is a circuit diagram according to embodiment 2 of the present invention. As shown in Fig. 4, in this embodiment, an electromagnetic coil 11 and an electrical adjustment unit 30 are connected in series.

[0037] When the resistance value R30 of the electrical adjustment unit 30 (here, the resistance value of the resistive element Rt) decreases, the combined resistance value of the entire circuit (the resistance value R11 of the electromagnetic coil 11 + the 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. This increases the magnetic force applied to the plunger 17, and the valve opening becomes larger. 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. This reduces the current flowing through the entire circuit, and therefore reduces the current supplied to the electromagnetic coil 11. This reduces the magnetic force applied to the plunger 17, and the valve opening becomes smaller.

[0038] If the valve opening becomes smaller as the temperature rises, the resistance element Rt may be a thermistor (e.g., an NTC thermistor or a CTR thermistor) whose resistance value decreases as the temperature rises, or a platinum temperature detector. In this case, the current supplied to the electromagnetic coil 11 increases, and the magnetic force applied to the plunger 17 becomes larger. This allows the valve opening to be increased.

[0039] On the other hand, if the valve opening degree increases as the temperature rises, a thermistor (e.g., a PTC thermistor) whose resistance value increases as the temperature rises is used for the resistance element Rt. This reduces the current supplied to the electromagnetic coil 11, and the magnetic force applied to the plunger 17 becomes smaller. This makes it possible to reduce the valve opening degree.

[0040] In this embodiment, in which the electromagnetic coil 11 and the electrical adjustment unit 30 are connected in series, the resistance value R30 of the electrical adjustment unit 30 changes with temperature, thereby controlling the combined resistance value of the entire circuit, thereby adjusting the current supplied to the electromagnetic coil 11 and, ultimately, adjusting the valve opening degree.

[0041] 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 R30 of the electrical adjustment unit 30, and the voltage applied to the circuit. This makes it possible to adjust the stroke of the plunger 17.

[0042] (Embodiment 3) Next, a third embodiment will be described. In this embodiment, a plurality of resistive elements are used to adjust the valve opening degree depending on the temperature. In this embodiment, the use of a plurality of resistive elements makes it possible to adjust both the valve opening degree depending on the temperature and the individual difference in stroke characteristics between products. 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. FIG. 5 is a circuit diagram according to the third embodiment of the present invention.

[0043] 5, the electrical adjustment unit 30 is connected in parallel with the electromagnetic coil 11. The electrical adjustment unit 30 includes a plurality of resistance elements (e.g., Rt1-Rt4), a resistance switching switch unit (first switch unit; e.g., SW1-SW4) that switches the current supply to the resistance elements, and a switch unit (second switch unit) SWm that switches the electrical adjustment unit 30 on / off.

[0044] 5, the multiple resistance elements Rt1-Rt4 in the electrical adjustment unit 30 are connected in series. 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 these resistance elements are connected in series are combined. The number of resistance elements is not limited to this example, and may be three or less, or five or more.

[0045] Each switch can be turned on and off manually. In this case, the solenoid valve body is not touched, so it can be operated without stopping the solenoid valve.

[0046] These resistance elements Rt1-Rt4 may include at least one of an NTC thermistor, a PTC thermistor, and a CTR thermistor. For example, all of the resistance elements Rt1-Rt4 may be resistance elements (e.g., thermistors) whose resistance value varies with temperature. Furthermore, these resistance elements Rt1-Rt4 may include resistance elements whose resistance value varies with temperature and resistance elements whose resistance value does not depend on temperature changes. Note that a "resistance element whose resistance value does not depend on temperature changes" is a resistance element whose resistance value varies less with temperature changes than a "resistance element whose resistance value varies with temperature," and for which there is no need to consider the variation in resistance value due to temperature changes.

[0047] Of these resistance elements Rt1-Rt4, some resistance elements can be allocated for adjusting the valve opening degree based on temperature, and the other resistance elements can be allocated for adjusting the individual differences in stroke characteristics between products. In this case, a thermistor (a resistance element whose resistance value varies with temperature) having characteristics corresponding to the first embodiment is used as the resistance element for adjusting the valve opening degree based on temperature. On the other hand, there is no restriction on the characteristics of the thermistor used as the resistance element for adjusting the individual differences in stroke characteristics between products, and a resistance element other than a thermistor (a resistance element that does not depend on temperature changes) may be used. Note that multiple resistance elements can be allocated for adjusting the valve opening degree based on temperature. This makes it possible to more appropriately adjust the valve opening degree based on temperature.

[0048] All of the resistance elements Rt1-Rt4 may be used for the purpose of adjusting the valve opening degree according to temperature.

[0049] The resistance value of the resistance element for adjusting the individual differences in stroke characteristics between products may be selected according to the resistance value of the electromagnetic coil 11, and may be set, for example, to a value several times to several hundred times the resistance value of the electromagnetic coil. In addition, the adjustment range of the current supplied to the electromagnetic coil 11 (current adjustment range) may be set, and the resistance value of each resistance element may be set so as to cover the range from the lower limit to the upper limit of the current adjustment range.

[0050] When the switch unit SWm is off, no current flows through the electrical adjustment unit 30, and therefore all of the current supplied from the external power source is supplied to the electromagnetic coil 11. Therefore, current adjustment to the electromagnetic coil 11 is performed with the switch unit SWm in the on state.

[0051] The electrical adjustment unit 30 can switch the current supply to the resistance elements in the electrical adjustment unit 30 by switching on / off the switch units SW1-SW4 provided in each of the resistance elements Rt1-Rt4. For example, when a certain switch unit is off, the path through the switch unit is cut off, so that only the corresponding resistance element functions. As a result, the resistance value of the electrical adjustment unit 30 increases by the amount of this resistance element.

[0052] However, since the resistance element that adjusts the valve opening degree according to temperature is always in use, the corresponding switch unit is always off, and therefore the switch unit corresponding to this resistance element may be omitted as appropriate.

[0053] In contrast, 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.

[0054] Alternatively, each resistance element may not be assigned a specific role, and all resistance elements may be used to adjust the valve opening degree due to temperature and to adjust for individual differences in stroke characteristics between products. In this case, the resistance elements Rt1-Rt4 may include multiple thermistors with different resistance values ​​and temperature characteristics. By changing the combination of thermistors by turning on / off the switch section of each resistance element, the original resistance value of the thermistor is used to adjust for individual differences in stroke characteristics between products, while the resistance value that changes due to temperature is used to adjust the valve opening degree due to temperature.

[0055] 6 is a circuit diagram in which the resistor elements Rt1-Rt4 of the electrical adjustment unit 30 are connected in parallel to the electromagnetic coil. Each resistor element Rt1-Rt4 constitutes a resistor element block BL1-BL4 together with a corresponding switch unit SW1-SW4. In each resistor element block BL1-BL4, the resistor element Rt1-Rt4 and the corresponding switch unit SW1-SW4 are connected in series. The multiple resistor element blocks BL1-BL4 are connected in parallel.

[0056] In this case, the current flowing through each resistance element is smaller than that when each resistance element Rt1-Rt4 is connected in series, so that the size of the resistance element used can be reduced. Also, even if the switch unit SWm for switching on / off the electrical adjustment unit 30 is not provided, the switch unit SWm is not required because all the current supplied from the external power source can be supplied to the electromagnetic coil 11 by turning off the switch units SW1-SW4 connected in series to each resistance element. As a result, the electrical adjustment unit 30 and, in turn, the solenoid valve can be made smaller. As described above, the switch unit corresponding to the resistance element that adjusts the valve opening degree according to temperature may be omitted as appropriate. The configuration of the electrical adjustment unit 30 shown in FIG. 6 is also applicable to each of the following embodiments.

[0057] Next, a method of adjusting stroke characteristics for the purpose of suppressing the variation in stroke characteristics between products will be described. FIG. 7 is a diagram for explaining a method of adjusting stroke characteristics for the purpose of suppressing the variation in stroke characteristics between products. In FIG. 7, the horizontal axis indicates the resistance value of the electrical adjustment unit 30, and the vertical axis indicates the lift-off current. The power supply current when the fluid starts to flow is called the lift-off current. The resistance value Rts on the horizontal axis is set for convenience of explanation. FIG. 7 shows the relationship between the resistance value of the electrical adjustment unit 30 and the lift-off current in three solenoid valves (1), (2), and (3) as a graph.

[0058] As shown in FIG. 7, when the resistance values ​​of the electrical adjustment units 30 are set to the same value, the lift-off current is the largest for the solenoid valve (1), followed by the solenoid valve (2) and then the solenoid valve (3). This results in variation (individual difference) in stroke characteristics between products. For example, when it is desired to set the lift-off current of each of the solenoid valves (1)-(3) to a predetermined current (set lift-off current) Is, referring to FIG. 7, the resistance value of the electrical adjustment unit 30 is set so that the solenoid valve (1) is the largest, followed by the solenoid valve (2) and then the solenoid valve (3). By setting the resistance values ​​of the electrical adjustment units 30 of the solenoid valves (1)-(3) in this manner, variation in stroke characteristics between products can be suppressed.

[0059] However, in this embodiment, since the stroke characteristics are also adjusted for the purpose of adjusting the valve opening degree due to temperature, it should be noted that the resistance value of the electrical adjustment unit 30, which is intended to adjust the stroke characteristics to suppress variation in stroke characteristics between products, may vary slightly from that shown in Figure 7.

[0060] According to this embodiment, the electrical adjustment unit 30 includes a plurality of resistance elements and a first switch unit for resistance switching that switches the current supply to the resistance elements. In addition, the plurality of resistance elements in the electrical adjustment unit 30 are connected in series. With this configuration, the resistance value of the electrical adjustment unit 30 can be easily switched by switching on / off the first switch corresponding to each resistance element.

[0061] This makes it possible to adjust for individual differences in stroke characteristics between products. By suppressing the variation in stroke characteristics between products, it becomes possible to appropriately control the flow rate of fluid in each flow path when multiple solenoid valves are used. 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 makes it easier to suppress variation in the magnetic characteristics, etc., of each solenoid valve and to keep the timing at which the fluid starts to flow consistent between devices.

[0062] Furthermore, since a plurality of resistance elements can be used for adjusting the valve opening degree depending on temperature, it becomes possible to more appropriately adjust the valve opening degree depending on temperature.

[0063] Moreover, according to this embodiment, there is provided a second switch unit that switches on / off the electrical adjustment unit 30. With this configuration, it is possible to stop the electrical adjustment unit 30 when adjustment of the current supplied to the electromagnetic coil 11 is not required. Also, it is possible to prevent the electrical adjustment unit 30 from malfunctioning.

[0064] (Embodiment 4) Next, a fourth embodiment will be described. FIG. 8 is a circuit diagram according to the fourth embodiment of the present invention. In FIG. 8, an electrical adjustment unit 30 including a plurality of resistance elements and the like is connected in series with an electromagnetic coil 11. The configuration of the electrical adjustment unit 30 in FIG. 8 is the same as that in FIG. 5. The electrical adjustment unit 30 may also have the same configuration as that in FIG. 6. In this embodiment as well, it is possible to adjust the valve opening degree due to temperature and to adjust for individual differences in stroke characteristics between products.

[0065] Next, a method for adjusting stroke characteristics for the purpose of suppressing the variation in stroke characteristics between products in this embodiment will be described. FIG. 9 is a diagram for explaining a method for adjusting stroke characteristics for the purpose of suppressing the variation in stroke characteristics between products in embodiment 4 of the present invention. In FIG. 9, the horizontal axis indicates the resistance value (R30) of the electrical adjustment unit 30, and the vertical axis indicates the lift-off voltage. The power supply voltage when the fluid starts to flow is called the lift-off voltage. FIG. 9 shows the relationship between the resistance value of the electrical adjustment unit 30 and the lift-off voltage in three solenoid valves (1), (2), and (3) as a graph.

[0066] As shown in FIG. 9, when the resistance values ​​of the electrical adjustment units 30 are set to the same value, the lift-off voltage is the highest for solenoid valve (1), followed by solenoid valve (2) and then solenoid valve (3), decreasing in that order. This results in variation (individual differences) in stroke characteristics between products. For example, when it is desired to set the lift-off voltages of the solenoid valves (1)-(3) to a predetermined voltage (set lift-off voltage) Vs, referring to FIG. 9, the resistance values ​​of the electrical adjustment units 30 are set so that the solenoid valve (3) is the highest, followed by solenoid valve (2) and then solenoid valve (3), decreasing in that order. By setting the resistance values ​​of the electrical adjustment units 30 of the solenoid valves (1)-(3) in this manner, variation in stroke characteristics between products can be suppressed.

[0067] However, in this embodiment, as in embodiment 3, adjustment of the stroke characteristics is also performed for the purpose of adjusting the valve opening degree due to temperature. Therefore, it should be noted that the resistance value of the electrical adjustment unit 30, which is intended to adjust the stroke characteristics to suppress variation in stroke characteristics between products, may vary slightly from that shown in Figure 9.

[0068] According to this embodiment, even when the electrical adjustment unit 30 is connected in series with the electromagnetic coil 11, the resistance value of the electrical adjustment unit 30 can be easily switched, so that it is possible to adjust the valve opening due to temperature and adjust for individual differences in stroke characteristics between products at the same time.

[0069] (Embodiment 5) Next, a fifth embodiment will be described. In this embodiment, the resistance value of the electrical adjustment unit 30 is automatically adjusted using various sensors. FIG. 10 is a block diagram illustrating the configuration of a solenoid valve according to a fifth embodiment of the present invention. The solenoid valve 1 in FIG. 10 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 a current supplied from an external power source, a voltage sensor that measures the value of a voltage applied to the electromagnetic coil 11 and the electrical adjustment unit 30, a temperature sensor that measures a temperature, a flow sensor that measures a flow rate, and the like.

[0070] The controller 90 includes a calculation device that performs various calculations, a memory that temporarily stores programs and various data, a storage that stores various information, etc. The controller 90 calculates the resistance value of the electrical adjustment unit 30 to be set based on the current value, voltage value, temperature, flow rate measured by the sensors 70, and information such as the set lift-off current and set lift-off voltage stored in the storage.

[0071] At this time, the controller 90 calculates the resistance value of the electrical adjustment unit 30 to be set in consideration of the influence of the adjustment of the stroke characteristics for the purpose of adjusting the valve opening degree according to the temperature. For example, the controller 90 stores in the storage a table in which the temperature corresponds to the resistance value of the electrical adjustment unit 30 for the purpose of adjusting the stroke for adjusting the valve opening degree according to the temperature, and extracts the resistance value of the electrical adjustment unit 30 for the purpose of adjusting the stroke for adjusting the valve opening degree according to the temperature from the measured temperature. The controller 90 also calculates the resistance value of the electrical adjustment unit 30 for the purpose of adjusting the stroke characteristics for suppressing the variation in the stroke characteristics between products. Then, the controller 90 adds up these resistance values ​​to calculate the resistance value of the electrical adjustment unit 30 for the purpose of adjusting the stroke characteristics for the purpose of adjusting the valve opening degree according to the temperature and for suppressing the variation in the stroke characteristics between products.

[0072] Then, the controller 90 turns on / off the switch section corresponding to each resistance element in the electrical adjustment section 30 based on the calculated resistance value, thereby adjusting the resistance value.

[0073] The on / off information of each switch unit after adjustment can be stored in storage, so that the resistance value of the electrical adjustment unit 30 can be set to the same value as the previous time when the device is started up next time.

[0074] According to this embodiment, it is possible to automatically perform the process 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.

[0075] Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments. A person skilled in the art can arbitrarily change, add, or convert the configurations of the embodiments described above without departing from the spirit of the invention. [Explanation of symbols]

[0076] 1 Solenoid valve 10 Solenoid section 11 Electromagnetic coil 13 Coil core 15 Casing 17 Plunger 19 Interior Space 20 Valve section 21 Valve body 23 Valve seat 25 Spring 27 Valve cover 30 Electrical adjustment section 70 Sensors 90 Controller

Claims

1. An electromagnetic coil; A plunger that operates by a magnetic field generated when a current is supplied to the electromagnetic coil; a valve portion connected to the plunger, the valve opening degree of which is adjusted with respect to the flow path in response to an operation of the plunger; an electrical adjustment unit that adjusts the current supplied to the electromagnetic coil by a resistive element whose resistance value varies with temperature; Equipped with Solenoid valve.

2. 2. The solenoid valve according to claim 1, The electrical adjustment unit is connected in parallel with the electromagnetic coil. Solenoid valve.

3. 2. The solenoid valve according to claim 1, The electrical adjustment unit is connected in series with the electromagnetic coil. Solenoid valve.

4. 2. The solenoid valve according to claim 1, The electrical adjustment unit includes a resistance element that is not dependent on temperature changes. Solenoid valve.

5. 2. The solenoid valve according to claim 1, The electrical adjustment unit has a plurality of the resistance elements and a resistance switching switch unit that switches current supply to the resistance elements. Solenoid valve.

6. 6. The solenoid valve according to claim 5, The electrical adjustment unit includes a resistance element that is not dependent on temperature changes, and a switch unit that switches the current supply to the resistance element. Solenoid valve.

7. The solenoid valve according to any one of claims 4 to 6, A plurality of the resistance elements in the electrical adjustment unit are connected in parallel. Solenoid valve.

8. The solenoid valve according to any one of claims 1 to 6, The resistance element includes at least one of an NTC thermistor, a PTC thermistor, and a CTR thermistor in response to a change in valve opening degree due to temperature. Solenoid valve.

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