Electromagnetic valve

Abstract

An electromagnetic valve comprises a valve body in which an inlet port and an outlet port for a fluid are formed, between which a valve seat and a valve chamber are formed, a valve body which is arranged in the valve chamber and can approach and move away from the valve seat, a piston which is arranged in the valve body and is moved in a direction in which it brings the valve body towards and away from the valve seat, a solenoid around which a coil is wound to drive the piston, a magnet which is attached to the piston, and a magnetic sensor which is provided on the valve body and detects the magnetic flux density of the magnet.

Description

solenoid valve

[0001] The present disclosure relates to solenoid valves.

[0002] Japanese Patent Laid-Open Publication No. 8-291887 (Patent Document 1) and Japanese Patent Publication No. 52-36287 (Patent Document 2) propose solenoid valves that are capable of detecting abnormalities or failures in the solenoid valve.

[0003] The solenoid valve of Patent Document 1 detects an abnormality by observing the current waveform of the coil for driving the plunger, but does not detect the position of the plunger itself.

[0004] In the solenoid valve of Patent Document 2, an abnormality is detected by a separately provided coil, but the position of the plunger itself is not detected.

[0005] In consideration of the above, the present disclosure aims to provide a solenoid valve that can detect a failure by detecting the position of the plunger.

[0006] The solenoid valve according to the first aspect comprises a valve body having an inlet and an outlet for a fluid, with a valve seat and a valve chamber formed therebetween; a valve element disposed within the valve chamber and capable of moving toward and away from the valve seat; a plunger disposed within the valve body and moving the valve element in a direction toward and away from the valve seat; a solenoid wound with a coil for driving the plunger; a magnet attached to the plunger; and a magnetic sensor provided in the valve body for detecting the magnetic flux density of the magnet.

[0007] In this solenoid valve, by passing current through the solenoid coil, the valve element can be moved in a direction away from the valve seat, thereby allowing fluid to flow from the inlet to the outlet.

[0008] A magnet is attached to the plunger, so when the plunger moves, the distance between the magnet and a magnetic sensor provided in the valve body changes, and the magnetic flux density of the magnet detected by the magnetic sensor changes.

[0009] For example, if the plunger that moves the valve element moves in the direction that separates the valve element from the valve seat, causing the magnet to approach the magnetic sensor, when the magnetic flux density detected by the magnetic sensor is large, it can be detected that the plunger has moved in the direction that separates the valve element from the valve seat. Also, when the magnetic flux density detected by the magnetic sensor is small, it can be detected that the plunger has moved the valve element toward the valve seat. Therefore, with this solenoid valve, it is possible to detect a malfunction of the solenoid valve from the relationship between the energization of the coil and the position of the plunger. With this solenoid valve, it is possible to detect the position of the plunger regardless of whether the coil is energized.

[0010] The solenoid valve according to the second aspect comprises a valve body having an inlet and an outlet for a fluid, with a valve seat and a valve chamber formed therebetween; a valve element disposed within the valve chamber and capable of moving toward and away from the valve seat; a plunger disposed within the valve body and moving the valve element in a direction toward and away from the valve seat; a solenoid wound with a coil for driving the plunger; and a magnetic sensor provided in the valve body and detecting the magnetic flux density of the coil passing through the plunger.

[0011] In this solenoid valve, by passing current through the solenoid coil, the valve element can be moved in a direction away from the valve seat, thereby allowing fluid to flow from the inlet to the outlet.

[0012] When the plunger moves, the distance between the plunger and the magnetic sensor provided on the valve body changes, and the magnetic flux density of the coil that passes through the plunger changes at the location where the magnetic sensor is installed.

[0013] For example, in the case of a solenoid valve in which a plunger that moves a valve element is configured to move in a direction in which the valve element contacts the valve seat and moves away from a magnetic sensor by energizing a solenoid coil, if the magnetic flux density detected by the magnetic sensor is equal to or less than a preset value, it can be detected that the plunger is moving in the direction in which the valve element contacts the valve seat.Also, if the magnetic flux density detected by the magnetic sensor when the coil is energized exceeds a preset value, it can be detected that the plunger is positioned in a direction in which the valve element moves away from the valve seat, i.e., that the plunger is not in the correct position.

[0014] In a third aspect, in the solenoid valve according to the first aspect, the plunger is cylindrical, and the magnet is inserted into and fixed to an upper end portion of a hole in the plunger.

[0015] In this solenoid valve, the plunger is cylindrical and the magnet is inserted into and fixed to the upper end of the plunger hole, making it lighter than a plunger with a cylindrical shape.

[0016] A fourth aspect is a solenoid valve according to any one of the first to third aspects, which has a pipe whose interior is connected to the valve chamber side and is isolated from the outside air, the plunger is arranged to slide up and down within the pipe, and the magnetic sensor is arranged outside the pipe.

[0017] The plunger is located inside a pipe that is connected to the valve chamber but is isolated from the outside air, so the fluid in the valve chamber does not leak to the outside air. If the magnetic sensor were located inside the pipe, it would be necessary to form a hole in the pipe to pass the wiring that outputs the magnetic sensor signal and to seal the gap between the hole and the wiring with a sealant or the like to prevent the fluid in the pipe from leaking to the outside air. However, by locating the magnetic sensor outside the pipe, this seal is not required, making the configuration simpler.

[0018] In a fifth aspect, in the solenoid valve according to the fourth aspect, there is provided an attractor made of magnetic stainless steel that connects the pipe and the valve body, and a compression coil spring is disposed between the attractor and the plunger.

[0019] When a magnetic stainless steel attractor is provided, energizing the solenoid coil magnetizes the attractor and plunger, generating a magnetic attraction between them and compressing the plunger against the resilience of the compression coil spring. When the solenoid coil is de-energized, the electromagnetic attraction force disappears and the resilience of the compression coil spring returns the plunger to its original position before it was attracted.

[0020] As described above, according to the solenoid valve of the present disclosure, it is possible to detect a malfunction of the solenoid valve by detecting the position of the plunger.

[0021] FIG. 1 is a longitudinal cross-sectional view illustrating the configuration of a solenoid valve according to a first embodiment of the present disclosure, showing a fully open state in which both the pilot valve and the main valve are open (a state in which the solenoid is not energized); FIG. 2 is a longitudinal cross-sectional view illustrating the configuration of a solenoid valve according to a first embodiment of the present disclosure, showing a fully closed state in which both the pilot valve and the main valve are closed (a state in which the solenoid is energized); FIG. 3 is a flowchart illustrating control of fault diagnosis of a solenoid valve according to the first embodiment; FIG. 4 is a longitudinal cross-sectional view illustrating the configuration of a solenoid valve according to a second embodiment of the present disclosure, showing a fully open state in which both the pilot valve and the main valve are open (a state in which the solenoid is not energized); FIG. 5 is a longitudinal cross-sectional view illustrating the configuration of a solenoid valve according to a second embodiment of the present disclosure, showing a fully closed state in which both the pilot valve and the main valve are closed (a state in which the solenoid is energized); and FIG. 6 is a longitudinal cross-sectional view illustrating the configuration of a solenoid valve according to a second embodiment of the present disclosure, showing a fully open state in which both the pilot valve and the main valve are open (a state in which the solenoid is not energized). 1 is a longitudinal cross-sectional view illustrating a configuration of a solenoid valve according to a second embodiment of the present disclosure, showing a fully closed state (a state in which the solenoid is energized) in which both the pilot valve and the main valve are closed. 2 is a flowchart illustrating control of a fault diagnosis of a solenoid valve according to a third embodiment.

[0022] [First embodiment] A solenoid valve 100 according to a first embodiment of the present disclosure will be described using Figures 1 and 2. Here, Figure 1 is a diagram for explaining the configuration of the solenoid valve 100 according to this embodiment, showing the fully open state, and Figure 2 shows the fully closed state. Note that in the following description of the embodiment, the up / down, left / right, and inside / outside directions refer to directions within the plane of Figures 1 and 3, and are not intended to narrow the technical scope of the present disclosure.

[0023] The solenoid valve 100 of this embodiment is a pilot-operated solenoid valve that can be used in the refrigeration cycle of an automotive air conditioner, etc., and includes a main valve portion 10 and a pilot valve portion 20 within a valve body 30. The flow of fluid between a fluid inlet 31 and an outlet 32 ​​is controlled by the main valve portion 10. The inlet 31 and the outlet 32 ​​are formed in the valve body 30. A main valve chamber 33 is provided between the inlet 31 and the outlet 32. As described below, a main valve element 40, an example of a valve element of the present disclosure, is housed within the main valve chamber 33 and is capable of sliding vertically. The main valve portion 10 is formed on one side (lower in the illustrated embodiment) of the sliding direction of the main valve element 40, and the pilot valve portion 20 is formed on the other side (upper in the illustrated embodiment). Female threads 30b and 30c are formed in the valve body 30. The valve body 30 and the main valve element 40 are made of an aluminum material, such as aluminum or an aluminum alloy.

[0024] A cylindrical plunger 50, which slides a pilot valve element 60, is disposed in a pipe 51 that opens downward at the center of the top of the solenoid valve 100. A cylindrical magnet 102 is inserted and fixed into the upper end of the hole in the plunger 50. As an example, the magnet 102 is magnetized with a south pole on one radial side and a north pole on the opposite radial side. The arrow Lm in the figure indicates the magnetic field lines. Since the plunger 50 of this embodiment is formed in a cylindrical shape, it is lighter than a plunger formed in a cylindrical shape.

[0025] The pilot valve element 60 is connected to the plunger 50 and is configured to slide up and down within the pipe 51 together with the plunger 50. That is, the plunger 50 slides up and down within the pipe 51 by the operation of the solenoid 70. An attractor 80 is provided as a means for driving the plunger 50 by the operation of the solenoid 70. The attractor 80, made of magnetic stainless steel, is magnetized when current is applied to the solenoid 70 by appropriate control means (not shown). The attractor 80 attracts the plunger 50 downward, overcoming the resilience of a spring 52, which is a compression coil spring, disposed between the attractor 80 and the plunger 50. The pipe 51 housing the plunger 50 is open downward and is fixed to the attractor 80 by appropriate means such as crimping or welding. The solenoid 70 is configured by surrounding a bobbin 70b, around which a coil 70a is wound, with a yoke 70c made of a magnetic material. A protruding portion 70d that protrudes outward is formed on the lower side (valve body side) of the yoke 70c.

[0026] A cover 104 that covers the solenoid 70 is provided on the top of the valve body 30. The cover 104 has an open top, which is closed by a lid 104A. A control board 106 serving as a control device is provided inside the cover 104, spaced above the plunger 50.

[0027] As an example, a magnetic sensor 108 that detects the strength of magnetic flux density is provided on the underside of control board 106, and electrical components such as a microcomputer 110 are mounted on the upper surface of control board 106. By arranging magnetic sensor 108 on the outside of pipe 51 in this way, it is not necessary to form a hole in pipe 51 through which wiring for outputting a signal from magnetic sensor 108 passes and to seal the gap between the hole and the wiring with a sealant or the like to prevent the fluid in pipe 51 from leaking to the outside air, thereby simplifying the configuration.

[0028] Although the magnetic sensor 108 in this embodiment is a Hall element, a magnetic sensor other than a Hall element, such as a magnetoresistive element, can also be used.

[0029] The microcomputer 110 can detect the position of the plunger 50 from the strength of the magnetic flux density detected by the magnetic sensor 108. That is, when the magnet 102 is located close to the magnetic sensor 108, the magnetic flux density is strong and the Hall output voltage is high. When the magnet 102 is located far from the magnetic sensor 108, the magnetic flux density is weak and the Hall output voltage is low. Therefore, by measuring the Hall output voltage, it is possible to detect whether the magnet 102 is close or far away, i.e., the position of the plunger 50. In this embodiment, the magnetic sensor 108 is located above the plunger 50 in the axial direction.

[0030] A female connector 112 is provided on the side of the cover 104 for electrically connecting the electrical circuit of the control board 106 to an external device (not shown) of the air conditioning system. One example of the external device is an air conditioner ECU of an automotive air conditioner. Electrical signals are transmitted and received between the control board 106 and the external device. The control board 106 can control the supply of electricity to the solenoid 70 (for example, by turning it on and off) in response to instructions from the external device.

[0031] The aspirator 80 has an overall multi-stage cylindrical shape with through holes formed at the top and bottom, and the pipe 51 is attached to it. In this state, the aspirator 80 is inserted or screwed into the upper large-diameter hole 30a formed in the valve body 30. Then, the male screw 71 is inserted into the through hole formed in the protruding portion 70d of the solenoid 70 inserted around the outer periphery of the pipe 51, and screwed into the female screw formed in the valve body 30. As a result, the aspirator 80 is pressed against and fixed to the valve body 30. The cylindrical shape of the aspirator 80 roughly consists of an upper small-diameter portion 81 and a lower large-diameter portion 82. The lower open end of the pipe 51 is fixed to the small-diameter portion 81. The large-diameter portion 82 is fixed to the valve body 30 as described above. The plunger 50 is housed in the pipe 51 fixed to the small-diameter portion 81 so that it can slide up and down.

[0032] A cylindrical main valve element accommodating portion (space) 82a is formed inside the large diameter portion 82 of the suction element 80, and the main valve element 40 is accommodated in this main valve element accommodating portion 82a so that it can slide vertically. The space is divided into upper and lower portions by the main valve element 40, so that the lower portion serves as the main valve chamber 33 and the upper portion serves as the pilot valve chamber 34. The outside of the large diameter portion 82 of the suction element 80 is sealed from the valve body 30 by an appropriate O-ring 83, and the inside of the large diameter portion 82 is sealed from the outer peripheral surface of the main valve element 40 (the portion that slides with the suction element 80) that slides inside the large diameter portion 82 by an appropriate main valve element sealing 43, preventing refrigerant leakage.

[0033] By configuring as described above, the inside of the pipe 51 is in communication with the pilot valve chamber 34 side but is isolated from the outside air.

[0034] In the illustrated embodiment of the present disclosure, the small diameter portion 81 and the large diameter portion 82 of the suction element 80 are integrated into one cylindrical member with a step interposed therebetween. Of course, depending on the embodiment, although not shown, the small diameter portion 81 and the large diameter portion 82 may be configured as separate members and fixed together by appropriate means. The key is that the suction element 80 must be able to attract and drive the plunger 50 when current is applied to the solenoid 70. In the present disclosure, the member that drives the plunger 50 by attraction and accommodates the main valve body 40 so that it can slide up and down is referred to as the suction element 80. It does not matter whether the suction element 80 is configured as a single member or multiple members.

[0035] The main valve section 10 is made up of a main valve packing 41 attached to the underside of the main valve element 40 and a main valve seat 35 formed between the inlet 31 and the outlet 32 ​​of the valve body 30. The pilot valve section 20 is made up of a pilot valve packing 61 attached to the underside of the pilot valve element 60 and a pilot valve seat 42 formed on the upper side of the main valve element 40. A pilot passage 45 and a pressure equalizing hole 44 are formed in the main valve element 40. The pilot valve seat 42 is provided at the end of the pilot passage 45. The pressure equalizing hole 44 communicates between the main valve chamber 33 and the pilot valve chamber 34, and the cross-sectional area of ​​the pressure equalizing hole 44 is smaller than the cross-sectional area of ​​the pilot passage 45.

[0036] The formation of this pressure equalizing hole 44 equalizes the pressure in the main valve chamber 33 and the pilot valve chamber 34, facilitating and smoothing the opening and closing operation of the main valve element 40. Furthermore, the formation of the pressure equalizing hole 44 allows the refrigerant in the main valve chamber 33 to quickly flow into the pilot valve chamber 34 even when there is a sudden pressure change from a compressor (not shown) connected to the solenoid valve 100 while the main valve unit 10 is closed, for example, when the compressor is started, thereby preventing the main valve unit 10 from opening or making it difficult to open.

[0037] In this solenoid valve 100, the valve body 30 and the main valve element 40 are made of an aluminum material such as aluminum or an aluminum alloy, and the attractor 80 is made of magnetic stainless steel. The entire main valve element 40, or at least the surface of the main valve element 40 that slides against the main valve element accommodating portion 82a of the attractor 80, is made of an anodized aluminum layer.

[0038] (Operation and Effect) Next, the operation of the solenoid valve 100 will be described with reference to Figures 1 to 3, taking as an example a case in which the solenoid valve 100 is applied to a refrigeration cycle. Figure 1 shows a state in which the solenoid 70 (coil 70a) is not energized. In this case, no suction force is generated in the attractor 80, so the spring 52 causes the plunger 50 to be lifted upward within the pipe 51, and the pilot valve portion 20 is in an open state. In addition, the main valve element 40 is lifted upward within the main valve chamber 33 by the spring 46, and the main valve portion 10 is in an open state.

[0039] When the compressor (not shown) is operated in this state, for example, high-temperature, high-pressure refrigerant flows from the inlet 31 through the main valve element 10 that is open in the main valve chamber 33 and through the outlet 32. Furthermore, the amount of refrigerant flowing from the pilot valve chamber 34 to the main valve chamber 33 via the pilot passage 45 is greater than the amount of refrigerant flowing from the main valve chamber 33 to the pilot valve chamber 34 via the pressure equalizing hole 44. Therefore, the pressure in the pilot valve chamber 34 becomes smaller than the pressure in the main valve chamber 33, and an upward force is generated on the main valve element 40. Together with the elastic force of the main valve element spring 46, the main valve element 10 is kept in a sufficiently open state, and the flow from the inlet 31 to the outlet 32 ​​is maintained.

[0040] 1, when the solenoid 70 is energized, the attractor 80 and the plunger 50 are magnetized, generating an electromagnetic attractive force between them, which pulls the plunger 50 down against the resilient force of the spring 52. Because the pilot valve element 60 is fixed integrally to the lower part of the plunger 50, the pilot valve element 60 slides up and down within the pipe 51 in unison with the movement of the plunger 50. The attractive force of the attractor 80 pulls the plunger 50 down, and at the same time, the pilot valve element 60 also slides downward. As a result, the pilot valve packing 61 provided below the pilot valve element 60 abuts against the pilot valve seat 42 formed on the upper side of the main valve element 40, which closes the pilot valve portion 20 as shown in FIG. 2 (i.e., blocks the pilot passage 45).

[0041] When the pilot passage 45 is closed, the only passage connecting the pilot valve chamber 34 and the main valve chamber 33 is the pressure equalizing hole 44, eliminating the pressure difference between the two valve chambers. When the plunger 50 further presses the main valve element 40 downward and slides it to its lowest point, the main valve packing 41 formed on the lower side of the main valve element 40 abuts against the main valve seat 35 formed in the valve body 30, closing the main valve unit 10. As a result, as shown in Figure 2, the main valve unit 10 is also closed, closing the flow path of the fluid, such as the refrigerant, and preventing it from flowing from the inlet 31 to the outlet 32.

[0042] Next, when the power supply to the solenoid 70 is stopped in the state shown in Fig. 2, the electromagnetic attraction force of the attractor 80 by the solenoid 70 is lost. The plunger 50 is pushed upward by the elastic force of the spring 52, and the pilot valve body 60 moves upward together with the plunger 50. The pilot valve packing 61 separates from the pilot valve seat 42 provided on the upper surface of the main valve body 40, and the pilot valve portion 20 enters the open state as shown in Fig. 3.

[0043] As a result, the pilot valve chamber 34 is connected to the outlet 32 ​​via the pilot passage 45 provided in the center of the main valve body 40, and the pressure in the pilot valve chamber 34 changes from high to low.

[0044] As a result, the main valve element 40 moves upward, and the main valve packing 41 fixed to the underside of the main valve element 40 separates from the main valve seat 35, resulting in an open valve state, as shown in FIG.

[0045] (Detection of Plunger Position) In the solenoid valve 100 of this embodiment, the plunger 50 moves in response to an instruction from an external device to turn on or off the power supply to the solenoid 70. However, even when the power supply to the solenoid 70 is turned on or off, there are cases where the plunger 50 does not move for some reason.

[0046] In this embodiment, the position of the plunger 50 can be detected as follows, and a fault diagnosis of the solenoid valve 100 can be performed. The fault diagnosis of the solenoid valve 100 will be described below with reference to the flowchart shown in FIG.

[0047] In step S100, the solenoid 70 (coil 70a) is not energized (energization OFF), and the valve is in an open state (see FIG. 1).

[0048] In step S102, it is determined whether the magnetic flux density detected by the magnetic sensor 108 is large (difference). Specifically, if it is determined that the magnetic flux density exceeds a preset value, it is determined that the magnet 102 is approaching the magnetic sensor 108, i.e., the plunger 50 is moving upward, the main valve packing 41 is separated from the main valve seat 35, and the main valve unit 10 is in an open state.

[0049] On the other hand, if it is determined that the magnetic flux density is equal to or less than the preset value, it is determined that the magnet 102 is separated from the magnetic sensor 108, and therefore the plunger 50 is not in the correct position when the power supply to the solenoid 70 is stopped. Here, "not in the correct position" refers to, for example, the state in which the plunger 50 has moved downward as shown in FIG. 2 (the main valve packing 41 is in contact with the main valve seat 35 formed in the valve body 30, and the main valve unit 10 is in the closed state).

[0050] If it is determined in step S102 that the main valve unit 10 is in an open state, the process proceeds to step S104, and if it is determined that the main valve unit 10 is in a closed state, the process proceeds to step S116. In step S116, for example, an external device can use a display device (not shown) or the like to notify the user that the solenoid valve 100 has failed.

[0051] In step S104, the solenoid 70 is energized to change the main valve unit 10 from an open state to a closed state.

[0052] In the next step S106, the magnitude of the magnetic flux density detected by the magnetic sensor 108 is determined. If it is determined that the magnetic flux density is equal to or less than a preset value, it means that the plunger 50 has moved downward, and the process proceeds to step S108. On the other hand, if it is determined that the magnetic flux density exceeds the preset value, it means that the plunger 50 has not moved downward even though current is applied to the solenoid 70, and the process proceeds to step S116, where a fault is notified to an external device.

[0053] In the next step S108, the power supply to the solenoid 70 is stopped in order to change the main valve unit 10 from the closed state to the open state.

[0054] In the next step S110, it is determined whether the magnetic flux density detected by the magnetic sensor 108 is large or small. If it is determined that the magnetic flux density exceeds a preset value, it means that the magnet 102 is approaching the magnetic sensor 108, the plunger 50 has moved upward, and the main valve unit 10 is in an open state, so the process proceeds to step S112.

[0055] On the other hand, if it is determined that the magnetic flux density is equal to or less than the preset value, it means that the magnet 102 is separated from the magnetic sensor 108, and the plunger 50 has not moved upward even when the power supply to the solenoid 70 is stopped. In other words, the main valve unit 10 is in a closed state, so the process proceeds to step S116, and a fault is notified to the external device.

[0056] In the next step S112, an instruction to stop the fault diagnosis is received from the external device, and in step S114, it is determined whether or not the instruction to stop the fault diagnosis has been received. If it is determined in step S114 that the instruction to stop the fault diagnosis has been received, the process ends, but if it is determined that the instruction to stop the fault diagnosis has not been received, the process returns to step S100 and the fault diagnosis continues.

[0057] In the solenoid valve 100 of this embodiment, by performing the failure diagnosis described above, the position of the plunger 50 can be detected to detect a failure of the solenoid valve 100, in this case, it is possible to detect the open / closed state of the main valve unit 10. Furthermore, the solenoid valve 100 configured in this embodiment can constantly detect the position of the plunger 50 regardless of whether or not the solenoid 70 is energized, by detecting the magnetic flux density with the magnetic sensor 108.

[0058] Furthermore, in the solenoid valve 100 of this embodiment, a failure of the solenoid valve 100 can be detected with a simple configuration in which the magnetic sensor 108 detects the magnitude of the magnetic flux density of the magnet 102 .

[0059] If the magnetic field lines of the solenoid 70 affect the detection of the magnetic flux density of the magnet 102 by the magnetic sensor 108, as an example, a magnetic shield 116 made of an electromagnetic steel plate or the like may be provided above the solenoid 70, as shown in FIG. 1.

[0060] Second Embodiment A solenoid valve 100 according to a second embodiment of the present disclosure will be described with reference to FIGS. 4 and 5. FIG.

[0061] The solenoid valve 100 of this embodiment differs from the first embodiment in the positions of the control board 106 and the magnetic sensor 108. In this embodiment, the control board 106 is located lower than in the first embodiment, and the upper end portion of the pipe 51 passes through the center portion of the control board 106.

[0062] The magnet 102 used in the second embodiment is magnetized so that one side in the vertical direction is the south pole and the other side is the north pole, and the magnetic sensor 108 is located close to the side of the pipe 51 so that the magnetic field line Lm passes through the magnetic sensor 108.

[0063] In the solenoid valve 100 of this embodiment, as in the first embodiment, the magnetic flux density of the magnet 102 detected by the magnetic sensor 108 changes depending on the position of the plunger 50, so that a failure of the solenoid valve 100 can be detected in the same manner as in the first embodiment.

[0064] 6 to 8, a solenoid valve 100 according to a third embodiment of the present disclosure will be described. Fig. 6 shows the main valve unit 10 in an open state, and Fig. 7 shows the main valve unit 10 in a closed state.

[0065] Unlike the first and second embodiments, the solenoid valve 100 of this embodiment does not have a magnet 102 provided on the plunger 50, but is configured such that the magnetic sensor 108 detects the magnetic field lines Lm of the solenoid 70, as shown by the arrow in FIG. 6 .

[0066] An example of fault diagnosis of the solenoid valve 100 will now be described with reference to the flowchart shown in FIG.

[0067] In step S200, the solenoid 70 is energized (ON) to change the main valve unit 10 from the open state shown in FIG. 6 to the closed state shown in FIG.

[0068] In the next step S202, while the solenoid 70 is energized (ON), the magnitude of the magnetic flux density detected by the magnetic sensor 108 is determined.

[0069] If it is determined that the magnetic flux density exceeds a preset value, the plunger 50 is positioned upward, i.e., the plunger 50 is not in the normal position when the solenoid 70 is energized (ON), and the main valve unit 10 remains in an open state, so the process proceeds to step S206, and a fault is notified to external devices.

[0070] On the other hand, if it is determined that the magnetic flux density is equal to or less than the preset value, the plunger 50 has moved downward and the main valve 10 is in a closed state, so the process proceeds to step S204.

[0071] In step S204, the power supply to the solenoid 70 is stopped (turned off) in order to change the main valve unit 10 from a closed state to an open state.

[0072] In the next step S208, it is determined whether or not an instruction to stop the fault diagnosis has been received from an external device. If it is determined that an instruction to stop the fault diagnosis has been received, the process is terminated, and if it is determined that an instruction to stop the fault diagnosis has not been received, the process returns to step S200 and the fault diagnosis is continued.

[0073] In the solenoid valve 100 of this embodiment, by performing the failure diagnosis described above, it is possible to detect whether the plunger 50 has moved to the correct position when current is applied to the solenoid 70. Furthermore, in the solenoid valve 100 of this embodiment, a failure of the solenoid valve 100 can be detected with a simple configuration in which the magnetic sensor 108 detects the magnitude of the magnetic flux density of the solenoid 70 that has passed through the plunger 50.

[0074] [Other Embodiments] One embodiment of the present disclosure has been described above, but the present disclosure is not limited to the above, and it goes without saying that various modifications can be made without departing from the spirit of the present disclosure.

[0075] In the above embodiment, the solenoid valve 100 is a pilot-type solenoid valve, and the position of the plunger 50 is detected by the magnet 102 attached to the plunger 50 of the pilot-type solenoid valve. However, the position of the plunger may also be detected by the magnet 102 attached to the plunger of a normal solenoid valve that is not provided with a pilot valve.

[0076] In addition, the control board 106 as a control device notifies external devices of failures and controls the on / off of the power supply to the solenoid 70. It is also capable of detecting abnormalities such as voltage abnormalities, temperature abnormalities (if a temperature sensor for measuring the temperature of the solenoid 70 is provided), and coil breaks in the solenoid 70 (compatible with On Board Diagnostics (vehicle self-diagnosis)), and can also reduce power consumption by, for example, lowering the current value passed through when the load is low.

[0077] The disclosure of Japanese Patent Application No. 2022-36648, filed on March 9, 2022, is incorporated herein by reference in its entirety. All documents, patent applications, and technical standards mentioned herein are incorporated herein by reference to the same extent as if each individual document, patent application, and technical standard was specifically and individually indicated to be incorporated by reference.

Claims

1. A solenoid valve comprising: a valve body having an inlet and outlet for a fluid, with a valve seat and a valve chamber formed therebetween; a valve element disposed within the valve chamber and capable of moving toward and away from the valve seat; a plunger disposed within the valve body and moving the valve element in a direction toward and away from the valve seat; a solenoid wound with a coil for driving the plunger; a magnet attached to the plunger; and a magnetic sensor provided in the valve body and detecting the magnetic flux density of the magnet.

2. A solenoid valve comprising: a valve body having an inlet and outlet for a fluid, with a valve seat and a valve chamber formed therebetween; a valve element disposed within the valve chamber and capable of moving toward and away from the valve seat; a plunger disposed within the valve body and moving the valve element in a direction toward and away from the valve seat; a solenoid wound with a coil for driving the plunger; and a magnetic sensor provided in the valve body and detecting the magnetic flux density of the coil passing through the plunger.

3. The solenoid valve according to claim 1, wherein the plunger is cylindrical, and the magnet is inserted into and fixed to an upper end portion of a hole in the plunger.

4. A solenoid valve according to any one of claims 1 to 3, comprising a pipe whose interior is connected to the valve chamber side and is isolated from the outside air, the plunger being arranged to slide up and down within the pipe, and the magnetic sensor being arranged outside the pipe.

5. The solenoid valve according to claim 4, further comprising a magnetic stainless steel attractor that connects the pipe and the valve body, and a compression coil spring disposed between the attractor and the plunger.

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