JPH0320185A - Solenoid valve - Google Patents

Abstract

PURPOSE:To find the right or wrong of an operating state easily as well as to aim at the facilitation of prevention against trouble occurrence by building in a malfunction detecting means which generates a malfunction detection signal when right or wrong of operation in a solenoid valve is detected and it is defective. CONSTITUTION:A solenoid valve 1 is constituted of a valve body 10 and a solenoid unit 20, and a malfunction detecting element 40 detecting a malfunction of the solenoid valve 1 is installed in this solenoid unit 20 together with an AC driving solenoid 25 consisting of a mold coil 22, iron core 23, and a plunger 24. The malfunction detecting element built-in this solenoid valve 1 outputs a malfunction detection signal when an operating state of the solenoid valve 1 has come to a response defective state or a continuous current defective state. With this constitution, right or wrong in the operating state can be easily found out, thus facilitation of prevention against trouble occurrence can be promoted.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a solenoid valve for controlling opening/closing or switching of a fluid flow path. [Conventional technology and its problems] Conventionally, solenoid valves can be controlled directly by electrical signals from a control circuit, and can also be easily controlled remotely, so it has been difficult to use fluid pressure such as hydraulic pressure or pneumatic pressure. It is widely used as a directional control valve in fluid pressure circuits (hereinafter referred to as "equipment"). When a solenoid valve is energized by applying AC or DC power supply voltage to the solenoid, the movable member moves in one direction, thereby changing the position of the valve body that is linked to the movable member and switching the flow path. There are two types of solenoid valves: direct-drive solenoid valves, in which the valve body is directly moved by a solenoid, and pilot-type solenoid valves, which use fluid pressure to assist in moving the valve body. Such solenoid valves are generally equipped with an indicator light that lights up when energized. This allows the operator to check whether or not the solenoid valve is energized when installing the solenoid valve or while the equipment is in operation.

By the way, in general, not only solenoid valves but also various devices incorporated into equipment, in addition to failures where the functions are completely lost, malfunctions in which the functions deteriorate due to wear of seal members or clogging with dust, etc. It may become a state. In malfunctioning conditions, the problem with the overall operation of the equipment is minor, and in many cases it is possible to maintain the equipment's operational status.
If you continue to use the equipment in a malfunctioning state, the functionality may deteriorate and reach a failure state, which may cause the equipment to suddenly stop operating. Therefore, in order to prevent equipment from suddenly stopping, we conduct timely inspections to detect equipment malfunctions at an early stage, and if malfunctions are detected, parts are replaced or cleaned, and equipment is operated properly. It is necessary to keep it in good condition. However, the problem with conventional solenoid valves is that workers cannot easily know whether the solenoid valve is in good working condition. In other words, at the time of inspection,
Maintenance work was extremely troublesome, as the solenoid valve had to be removed from the equipment and disassembled. Inspections require a lot of time and effort, especially when a large number of solenoid valves are incorporated into the equipment. Furthermore, even if a malfunction occurred in equipment due to malfunction of a solenoid valve, it was not possible to quickly confirm that the cause of the malfunction was the solenoid valve. SUMMARY OF THE INVENTION In view of the above-mentioned problems, it is an object of the present invention to provide a solenoid valve that can easily determine whether the operating state is good or bad and can easily prevent failures. [Means for Solving the Problem] In order to solve the above-mentioned problem, the invention of claim 1 is a solenoid valve configured to control a wave path of a fluid using a solenoid activated by energization, It is characterized by having a built-in malfunction detection means that detects whether the solenoid valve is operating properly and generates a malfunction detection signal when the solenoid valve is malfunctioning. The invention of claim 2 is characterized in that the malfunction detecting means of the invention of claim 1 detects a malfunction when the response time of the pressure sensor and the flow path control based on the output signal of the pressure sensor exceeds a predetermined time. and a response failure detection means that generates a signal. The invention according to claim 3 is characterized in that the malfunction detection means according to the invention according to claim 1 includes energization failure detection means that generates a energization failure signal when the magnitude of the energizing current of the solenoid becomes a value outside a certain range. It is composed of the following characteristics: [Function] A solenoid is activated by electricity and controls the flow path of fluid. The malfunction detection means detects whether the solenoid valve is operating properly, and generates a malfunction detection signal when the solenoid valve is malfunctioning. A pressure sensor outputs an output signal according to pressure. The poor response detection means generates a poor response signal when the response time for controlling the flow path exceeds a predetermined time based on the output signal of the pressure sensor. The energization failure detection means generates an energization failure signal when the magnitude of the energizing current of the solenoid falls outside a certain range. [Examples] Examples of the present invention will be described below with reference to the drawings. FIG. 1 is a cross-sectional front view of a solenoid valve l according to the present invention. The solenoid valve l includes a valve body lO and a solenoid unit 2.
It consists of 0. The valve body 1O is composed of a valve body 11 having a valve chamber 11a passing through the center in the axial direction, an end cover 12 that closes one end of the valve body 11, and a pilot base 13 connected to the other end of the valve body 11. The valve body l1 has boats (vents) P, A, B, R, which respectively communicate with the valve chamber 11a. ．． R8
is placed at an appropriate location. Boat P is connected to a pneumatic source (not shown) via piping, and boats A and B are connected to a pneumatic cylinder 90, which is an external device. Port R. , R
m is the exhaust port. A spool 14 is inserted into the valve chamber 11a, and has a small-diameter piston l7 and a large-diameter piston 18 arranged at both ends, respectively. The valve chamber 11a is partitioned by the close contact between the protrusions formed at appropriate places on the inner wall of the valve chamber 11a, and the ports P, A, B, R. , Rl can be switched. Further, the valve body 11 has a pressure sensor 30 built into the port A for detecting malfunction of the solenoid valve l. The pressure sensor 30 has a built-in waveform shaping circuit that converts a signal depending on the level of pressure into an on/off signal. The end cover 12 is provided with a piston chamber 17a in which the piston l7 slides, and the piston chamber l7a is always connected to the port P via a ventilation passage 15a inside the end cover 12 and a ventilation passage 15 bored in the valve body 11. It communicates with The pilot base l3 is provided with a piston chamber 118a in which the piston 18 slides, and a pilot valve l9 that opens and closes by movement of a plunger 24, which will be described later. Port PR is an exhaust port for exhausting pilot air from the piston chamber 18a. On the other hand, the solenoid unit 20 includes a molded coil 2.
2, an iron core 23, and an AC-driven solenoid 25 consisting of a plunger 24, as well as a malfunction detection section 40 for detecting malfunction of the solenoid valve l. The output signal of the pressure sensor 30 is input to the malfunction detection section 40 via a lead wire (not shown). Furthermore, display LEDs 31 and 32 for displaying the operating status of the solenoid valve 1 are provided on the top surface of the solenoid unit 20 at positions that are easily visible from the outside. Display LE
D31 emits green light when turned on, and the display LED 32 emits red light. Electrical connection between the solenoid valve l and a control device (not shown) is made through the fixed socket 26a of the solenoid unit 20.
This is done via a group of lead wires 27 that are wired in one-touch using a detachable plug 26b. In the figure, 15b is an air passage for guiding pilot pressure to pilot valve l9, 19a is a pot that moves in conjunction with plunger 24, and 29 is a manual operation member for manually opening and closing pilot valve l9. ．． The solenoid valve 1 configured as described above is a well-known 5-port 2
Operates as a direct pilot type directional control valve. Next, the basic operation of the solenoid valve l will be briefly explained. When no AC voltage is applied to the solenoid 25, that is,
When de-energized, the plunger 24 is compressed by the compression spring 28.
is pressed against the pilot base l3, and the pilot valve 19 is in the closed state (the state shown in Fig. 1). In this case, the piston l is caused by the air pressure supplied from the boat P.
7 is pressed, the spool 14 moves to the right end side as shown in Fig. 1, and a wave path is formed in which port A and boat P communicate with each other, and boat B and port Rg communicate with each other. When the solenoid 25 is energized, the plunger 24 is drawn toward the iron core 23 by magnetic force against the biasing force of the compression spring 28, and the pilot valve l9 opens. As a result, the ventilation path 15
．． Pilot pressure from port P is also applied to piston 18 via port 15b. Piston 18 is piston l7
Since the diameter is larger than that of boat R., spool l4 moves to the left end side, and port A is connected to boat R. and boat B communicates with port P.
The valve chamber 11a is partitioned and the flow path is switched so as to communicate with the valve chamber 11a. In this way, when the operating state of the solenoid valve 1 is good, switching control of the compressed air flow path is performed by turning on and off the energization to the solenoid 25, and the flow path of the compressed air is controlled to be switched between the port A and the boat B.
The pressure at changes quickly with a predetermined response time. However, for example, the movement of the spool l4 may be slowed down due to leakage of airtightness due to wear of the sealing member provided at a proper location, or due to the entrapment of dust. If the movement of the subur 14 is slow, the response time of pressure changes at ports A and B to on/off of energization becomes longer. In other words, the operating state of the solenoid valve 1 becomes a poor response state.

Also, if minute dust gets mixed in between the plunger 24 and the iron core 23, the plunger 2
4 and the iron core 23 become incomplete, the plunger 24 vibrates in the axial direction, and the operating state of the solenoid valve 1 becomes a energization failure state. FIG. 5 is a diagram showing changes in the current applied to the solenoid 25. When the operating state of the solenoid valve l is good, the magnitude of the current gradually decreases as the plunger 24 moves from startup, as shown by the curve j in the figure, and the magnitude of the current decreases between the plunger 24 and the iron core 23. After adsorption, the holding current value h becomes constant. On the other hand, in an energization failure state, as shown by curve k, the current does not decrease to the holding current value h and fluctuates as the plunger 24 vibrates. If left in a state of poor energization, the molded coil 22 may break or the solenoid valve l may malfunction. The malfunction detection unit 40 built into the solenoid valve l of this embodiment sends a malfunction detection signal SO when the operating state of the solenoid valve l becomes a malfunction state such as the above-mentioned poor response state or poor energization state. Outputs . FIG. 2 is a block diagram showing the structure of the malfunction detection section 40, and FIGS. 3 and 4 are timing charts showing the operation of the malfunction detection section 40. The malfunction detection section 40 includes a conduction failure detection section 4l, a response failure detection section 42, and a signal output section 43. The energization failure detection unit 41 includes a current-voltage conversion unit 5l that converts the value of the energized current of the solenoid 25 into a voltage, and a reference voltage generator that generates a reference voltage corresponding to a predetermined value Xa (see FIG. 5) of the energized current. section 52, when the output of the current-voltage conversion section 51 is larger than the output of the reference voltage generation section 52, rl{J
A comparator 53 outputting a signal S53 and a signal S5
3 is rH, the signal holding section 54 outputs a conduction failure signal Sl (active high). The current-voltage converter 51 has a time constant circuit to avoid following the peak current at startup. Poor response detection unit 4
2 is an edge detection unit 6L that detects the on/off timing of energization to the solenoid 25; an edge detection unit 62 that detects the rising and falling timings of the output signal S30 of the pressure sensor 30; and an edge detection unit 61 that detects the timing of the output signal S61 of the edge detection unit 61. It consists of a timer part 63 that outputs a poor response signal 32 (active high) as a time-up signal when the time t1 is started and a time tl is counted, and a signal holding part 64 that holds the poor response signal S2. The timer section 63 is reset by the output signal S62 of the edge detection section 62. The signal output unit 43 also outputs a energization failure signal S.
an OR circuit 71 that outputs a malfunction detection signal SO when at least one of the response failure signal S2 and the response failure signal S2 is "H";
and an AND circuit 72 that outputs a good operation signal S72 only when both the energization failure signal S1 and the response failure signal S2 are "L".The operation failure detection signal SO is
A good operation signal 372 is sent to a control device (not shown) and applied to the display LED 32, and is applied to the display LED 31. In FIG. 3, when the solenoid valve 1 is operating well, the energization failure signal S1 is rl,J, but the energization current is at the value . When the voltage exceeds the voltage and becomes a poor energization state, the comparator 53
When the output signal S53 first becomes rHJ, the energization failure signal Sl becomes "H". Therefore, the malfunction detection signal SO also becomes "H" and the display LED 32 lights up. The rl{J state of the energization failure signal S1 continues until the operator confirms that the operating state of the solenoid valve 1 has become defective and resets the signal holding unit 54 by operating a reset switch (not shown). Ru. Note that the control device displays the occurrence of a malfunction on a central control panel or the like based on the malfunction detection signal SO. In FIG. 4, even if the solenoid valve 1 is operating well, a predetermined response time t from the energization on/off timing is shown.
o, the output signal S30 of the pressure sensor 30 falls or rises. At this time, the timer part 63 starts timing operation at the on/off timing, but is reset before the time is up at the falling or rising timing of the output signal S30 of the pressure sensor 30, so the response failure signal S2 is rl, J. When the response time of the solenoid valve l, that is, the time difference between the timing of energization and the timing of change of the output signal S30 is in a poor response state that is longer than the predetermined time tl (tl>to), the timer part 63 times out. Then, the response failure signal S2 is r
It becomes H. Therefore, the malfunction detection signal SO is rl
{J, and the display LED 32 lights up. The "H" state of the poor response signal S2 is maintained until the signal holding unit 64 is reset.In other words, in the solenoid valve 1, when the operating state is good, the display LED 31, which emits green light, lights up. Once the operating state becomes defective, the red indicator LED 32 lights up until a reset operation is performed. The hindrance in operation is slight, and the operation of the solenoid valve l can be continued.According to the above-mentioned embodiment, the display LED 32 is provided to indicate that the operating state has become defective, so that it can be checked at the time of inspection. , the operation status of the solenoid valve I can be checked visually from the outside.In addition, by outputting the malfunction detection signal SO to the central control device, the operation status of the solenoid valve I can be checked centrally. In the above-described embodiment, the malfunction detection unit 40 detects a malfunction when the total usage time or number of times of use of the solenoid valve l reaches a set value. Life detection means for outputting a signal may be provided. In the above embodiment, pressure sensor 30 may be provided at port A and port B.
0 may be provided, and the poor response signal S2 may be generated when the response time of pressure change in at least one port becomes longer than the set time. In the embodiments described above, the configurations of the energization failure detection section 4l and the response failure detection section 42, the shape and material of the valve body IO and the solenoid unit 20, etc. can be changed in various ways.
For example, as the timer part 63, charging is started by the output signal 561 of the edge detection part 61, and the edge detection part 6
2, a comparator circuit that outputs a response failure signal S2 when the charging voltage of the capacitor becomes higher than a predetermined voltage, or a counter that counts the number of reference clock pulses, as well as a known timer. means can be used. [Effects of the Invention] According to the present invention, it is possible to easily know whether the operating state is good or bad, and it is possible to easily prevent the occurrence of failures.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional front view of a solenoid valve l according to the present invention, FIG. 2 is a block diagram showing the configuration of the malfunction detection section, FIGS. 3 and 4 are timing charts showing the operation of the malfunction detection section, FIG. 5 is a diagram showing changes in the energizing current of the solenoid. l... Solenoid valve, 25... Solenoid, 30... Pressure sensor, 40... Malfunction detection section (malfunction detection means), 4l...Positive energization detection section (poor energization detection means), 42...Poor response detection section (poor response detection means),
SO...Poor operation detection signal, S1...Poor energization signal, S2...Poor response signal.

Claims (3)

[Claims] (1) A solenoid valve configured to control a fluid flow path using a solenoid activated by energization, which detects whether the solenoid valve is operating properly and generates a malfunction detection signal when the solenoid valve is malfunctioning. 1. A solenoid valve characterized by having a built-in means for detecting malfunction that occurs. (2) The malfunction detection means includes a pressure sensor, and a response failure detection means that generates a response failure signal when the response time of control of the flow path exceeds a predetermined time based on the output signal of the pressure sensor. 2. The solenoid valve according to claim 1, comprising: (3) The malfunction detection means is characterized in that the malfunction detection means includes a conduction failure detection means that generates a conduction failure signal when the magnitude of the energization current of the solenoid falls outside a certain range. 1. The solenoid valve according to 1.