JP2648399B2 - Monitor of solenoid valve - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a solenoid valve monitor, and more particularly to a solenoid valve monitor for operating an air clutch and a brake of a press machine.

[0002]

2. Description of the Related Art In order to ensure press working safety, a monitor is provided on a solenoid valve for operating an air clutch and a brake of a press machine. According to safety regulations, a solenoid valve for operating an air clutch or a brake is hardly damaged, and even if the solenoid valve is damaged, it is required to work on the safe side and stop the press machine.

An air clutch and a brake are operated by a pneumatic cylinder and controlled by a solenoid valve. In order to ensure safe operation of this solenoid valve, there is little possibility that two valves will malfunction at the same time. Therefore, when two valves are provided in parallel and they do not operate synchronously, malfunction is detected by the monitor. Japanese Patent Application Laid-Open No. 55-112407, "Double Safety Valve Monitor", discloses a dual valve type solenoid valve which is provided with two valves in parallel and malfunctions when they do not operate synchronously.

[0004]

In the conventional dual-type solenoid valve, an inlet for detecting pressure is opened in a sheet on the supply side of the valve and compressed air is guided to a piston chamber of the monitor. If the pressure fluctuates or the operating pressure rises, the detected pressure changes, so that the monitor operates as a malfunction even though the valve does not malfunction, so-called pseudo detection.

[0005] Further, both valves operate synchronously during normal operation. However, if one of the valves is operated later, a difference in the detected pressure may occur and the monitor may function as a malfunction. Even if the trailing of one valve does not hinder the machine, the machine is stopped and the working efficiency is reduced.

[0006]

In view of the above circumstances, the present invention has a supply port, a load port, and an exhaust port in order to avoid false detection and not to be sensitive to detected pressure. Two valves for inflow and cutoff from the load port to the exhaust port and from the load port to the exhaust port are arranged in parallel, and the valves are seated on the supply side seat and separated from the supply side seat and the exhaust side seat. And an exhaust valve part that moves to and away from the piston chamber. Compressed air that moves the piston to the left and right ends of the piston chamber that slides the piston is guided from an inlet port opened in the supply side sheet, and a signal is generated by movement of the piston. A monitor for an electromagnetic valve which has a switch for generating a signal when the two valves are out of synchronization and generates a signal to the switch based on a difference in the detection pressure of the inlet. The outlet is a monitor solenoid valve communicated.

[0007] The present invention is also a monitor of an electromagnetic valve in which a charge tank is communicated with a flow path connecting an inlet and a piston chamber. Further, a step portion is provided in which a spring receiver is slidably provided on the small diameter portions at both ends of the piston, a coil spring is contracted between the housing and the spring receiver, and both spring receivers are formed in the housing in a neutral state of the piston. It is a monitor of the solenoid valve contacted with.

Further, there is provided a monitor for an electromagnetic valve in which a flow passage penetrating the piston is formed and an orifice is provided in the flow passage.

[0009]

The difference in the detected pressures occurs when the two valves are not synchronized, and compressed air is supplied from the inlet to the piston chamber. However, since the inlet is connected to the discharge port of the exhaust side sheet, The mouth can be enlarged. The two valves are not synchronized, and a difference occurs in the detected pressure, and compressed air is supplied from the inlet to the piston chamber.The inlet may be provided with a surge tank before reaching the piston chamber, or the piston may be over a predetermined pressure. Since it is set so that it moves only after the compressed air is guided, or because a flow path is formed in the axis portion of the piston and an orifice is provided in the flow path, the detection pressure is not easily received, and the pseudo detection is not performed.

[0010]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram of a first embodiment of the present invention. First, a dual valve type solenoid valve will be described. The solenoid valve has three ports, a supply port P, a load port A, and an exhaust port R.
Controls the pneumatic cylinder that activates the air clutch or brake. FIG. 1 shows a state in which the compressed air supplied from the supply port P is shut off by the valve 1, the compressed air in the load port A is discharged from the exhaust port R, and the pneumatic cylinder is not operated. In FIG. 2, the compressed air from the supply port P passes between the valve 1 and the supply-side seat 2 and is supplied to the pneumatic cylinder via the load port A, and the pneumatic cylinder is in an activated state.

The valve 1 has a large-diameter exhaust valve portion 3 formed on the upper side and a supply valve portion 4 formed on the lower side and connected by a shaft portion 5 in the figure, and the shaft portion 5 is located at the load port A. And the exhaust valve 3
Is located on the exhaust side seat 6, the supply valve section 4 is located below the supply side seat 2, and the valve 1 urges the supply valve section 4 upward by the coil spring 7 to move the supply valve section 4 on the supply side. The exhaust valve section 3 is seated on the seat 2 and closed, while the exhaust valve section 3 is opened apart from the exhaust side seat 6 and communicates with the exhaust port R above the exhaust side seat 6. Supply port P and load port A
Are connected in parallel by air flow paths, and a valve 1 is connected to each air flow path.
Are arranged, and the supply port P and the exhaust port R are connected in parallel by an air flow path, and the valve 1 is disposed in each air flow path.

The upper part of the exhaust valve part 3 of the valve 1 is a piston.
11 and slidably fitted to the piston chamber 12. The piston chamber 12 communicates with the pilot flow path 13, and the pilot flow path 13 communicates with the supply port P. The pilot flow path 13 is provided with a pilot valve 14 for flowing or blocking compressed air from the supply port P into the piston chamber 12. The pilot valve 14 is urged from above and below by contracted coil springs 15 and 16. A solenoid 17 is arranged above the pilot valve 14, and when the solenoid 17 is excited, the pilot valve 14 is pushed downward by the solenoid 17 against the urging force of the coil spring 16 to open the pilot flow path 13. Then, the compressed air from the supply port P flows into the piston chamber 12 (the state shown in FIG. 2). When the solenoid 17 is not excited, the pilot valve 14 is pushed upward by the urging force of the coil spring 16 and the pilot flow path 13
And the compressed air from the supply port P is supplied to the piston chamber 12.
Do not let it flow into the tank (as shown in Fig. 1). The pilot flow path
13 is closed by the pilot valve 14, and the valve 1 is urged upward by the urging force of the coil spring 7 so that the valve 1
In order to discharge the compressed air in the piston chamber 12 when the piston 11 rises, the piston chamber 12 and the exhaust port R
And communicate.

FIG. 2 shows a state in which the pneumatic cylinder is activated, the solenoid 17 is energized, the pilot valve 14 is depressed against the urging force of the coil spring 16 and opens, and compressed air from the supply port P is released. After flowing into the piston chamber 12 through the pilot flow path 13, the valve 1 is pushed downward against the urging force of the coil spring 7. Then, the exhaust valve portion 3 of the valve 1 sits on the exhaust side seat 6 and closes, the valve between the supply valve portion 4 and the supply side seat 2 opens and opens, and the compressed air from the supply port P is supplied by the supply valve. Between the unit 4 and the supply side sheet 2, the load port A
And supplied to the pneumatic cylinder.

Next, when the solenoid 17 is not excited, the pilot valve 14 is pushed upward by the urging force of the coil spring 16 as shown in FIG. No air is supplied to the piston chamber 12. Then, the valve 1 is pushed upward by the urging force of the coil spring 7, the supply valve portion 4 is seated on the supply side seat 2 and is closed, and the exhaust valve portion 3 is opened apart from the exhaust side seat 6 and supplied. Compressed air from port P is shut off,
The compressed air of the load port A is supplied to the exhaust valve section 3 and the exhaust side seat 6.
, And is discharged from the exhaust port R, and the pneumatic cylinder is not operated.

In this dual valve type solenoid valve,
Two valves are provided in parallel, and when they do not operate synchronously, malfunction is detected by the monitor. In order to detect whether or not the two valves 1 are synchronized, a detection pressure inlet 21 is opened in the supply side seat 2 of each valve 1 and a piston chamber 23 in which a piston 22 is slidably provided. The piston 22 is moved by the differential pressure of the detection pressure generated when the two valves 1 are not synchronized, and the movement is detected by the limit switch 24 and monitored.

A piston 22 is slidably provided in the piston chamber 23, and a concave portion 25 is formed in an intermediate outer peripheral portion of the piston 22, and a switch operating piece of a limit switch 24 is provided in the concave portion 25.
26 is brought into contact (the state shown in FIGS. 1 and 2). Both sides of the concave portion 25 are outer peripheral portions 27. The inlet 21 is connected to the piston chamber 23 through the flow path 28.
And the piston 22 is operated. 1 and 2, since the two valves 1 are synchronized, the inlet 21
, The piston 22 does not move, and the switch operating piece 26 of the limit switch 24 is located in the concave portion 25 of the piston 22, indicating that it is in a normal operating state.

In the state shown in FIGS. 3 and 4, since the two valves 1 are not synchronized, there is a difference in the detected pressure at the inlet 21 and the pressure is transmitted from the inlet 21 to the flow path 28 and the piston chamber 23. As a result, the piston 22 moves, the switch operating piece 26 of the limit switch 24 comes into contact with the outer peripheral portion 27 of the piston 22, and the limit switch 24 outputs a signal indicating malfunction. By the way, the compressed air is detected by opening the inlet 21 in the supply side sheet 2. However, if the instantaneous pressure fluctuation or the working pressure of the inlet 21 increases, the detected pressure changes, and therefore, the valve In some cases, so-called spurious detection is performed in which the monitor functions as a malfunction even though the monitor does not malfunction. When both valves operate normally, they operate synchronously. However, when one of the valves operates with a delay, a difference in detected pressure may occur and the monitor may function as a malfunction. The machine may be stopped even if the trailing of one of the valves does not hinder the machine.

In order to solve the above problems, it is effective to reduce the fluctuating pressure. Therefore, the inlet 21 may be detected by narrowing the inlet 21 to a smaller diameter of, for example, about 1.2 mm to 0.8 mm. However, if the orifice of the inlet 21 is too small, false detection may occur due to air quality including drain and oil. Therefore, in the present invention, a small-diameter discharge port 31 communicating with the introduction port 21 is provided in the exhaust side sheet 6 in order to reduce the fluctuation pressure without narrowing the introduction port 21 to a smaller diameter. A part of the compressed air led from the inlet 21 is discharged from the outlet 31, so that the inlet 21 can be enlarged.

1, 2 and 3, the discharge port 31 is provided on the exhaust side seat 6 of the same valve 1, but in FIG. 4, the discharge port 31 is connected to the exhaust side seat 6 of the other valve 1. This is an example in which the exhaust provided in the above is increased. The compressed air introduced from the inlet 21 reaches the piston chamber 23 via the flow path 28 and operates on the piston 22. However, the charge tank 32 having a volume on the side of the piston chamber 23 is connected to the flow path 28. Then, the guided compressed air accumulates in the charge tank 32 and then flows into the piston chamber 23,
It is difficult to receive the detection pressure sensitively, and false detection can be prevented.

The piston 22 is slidably provided in a piston chamber 23. Both ends of the piston 22 are formed in a small diameter portion 33 from a central portion, and a spring receiver 34 is slidably fitted in the small diameter portion 33. A coil spring 35 is contracted between the receiver 34 and the housing 36 to urge the piston 22 from both sides toward the center. At the same interval between the step 37 at the boundary between the small diameter portion 33 of the piston 22 and the center and the step 37 on the other side, the housing 36
A step 38 is also provided. When the valve 1 shown in FIGS. 1 and 2 is synchronized and the piston 22 is in the neutral position, the step 37 of the piston 22 and the step 38 of the housing 36 are in the same position, and the spring receiver 34 is in the two positions. The two coil springs 35 contracted and contracted simultaneously at 37 and 38 urge the piston 22 toward the center.

In the state shown in FIGS. 3 and 4, when the compressed air is guided from the inlet 21 to the piston chamber 23 without the valve 1 being synchronized and the piston 22 moves to the left, the spring receiver 34 of the right coil spring 35 moves. Is the step of the housing 36
When the stepped portion 37 of the piston 22 separates from the spring receiver 34, the urging force applied to the piston 22 toward the center of the right coil spring 35 stops acting, and the compressed air exceeding the urging force is applied. Is guided to the piston chamber 23, and then the piston 22 moves to the left. Therefore, the piston 22 which is urged by the coil springs 35 on both sides and is balanced and in the neutral position has the spring receiver 34 in contact with the step portion of the housing 36. It takes time to rise, and it is difficult to receive the detection pressure sensitively, and false detection can be avoided.

In FIG. 5, a flow path 41 penetrating the central shaft portion is formed in the piston 22 and an orifice 42 is provided in the center thereof, but compressed air guided from the inlet 21 to the piston chamber 23 is passed therethrough. The detection pressure is relaxed so that the detection pressure is not sensitively received, thereby avoiding false detection.

[0023]

According to the present invention, as described above, there are provided two supply ports, a load port, and an exhaust port, and two valves for inflow and shutoff from the supply port to the load port and from the load port to the exhaust port. Arranged in parallel, the valve has a supply valve portion that sits on and separates from the supply side seat and an exhaust valve portion that sits on and separates from the exhaust side seat, and the left and right ends of a piston chamber that slides the piston A switch that guides compressed air that moves the piston to the inlet from the supply-side seat and generates a signal when the piston moves, switches when the two valves are out of synchronization by the difference in the detected pressure of the inlet. In the monitor of the electromagnetic valve configured to generate a signal, a monitor of the electromagnetic valve in which the introduction port communicates with the discharge port opened in the exhaust side sheet, so that the size of the introduction port can be increased. That.

Further, according to the present invention, the two valves are not synchronized, and a difference occurs in the detected pressure, and compressed air is supplied from the inlet to the piston chamber, but the inlet is provided with a surge tank until reaching the piston chamber. The piston is set so that it moves only when compressed air of a predetermined pressure or higher is introduced, or the piston is provided with a flow passage in the axial line and an orifice in the flow passage, so it is sensitive to the detected pressure. Difficult to detect falsely.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing an operating state when a solenoid is not excited in a specific embodiment of a monitor of an electromagnetic valve of the present invention.

FIG. 2 is a longitudinal sectional view showing an operating state when a solenoid is excited.

FIG. 3 is a longitudinal sectional view showing an operation state when both valves are not synchronized, that is, when the valves malfunction.

FIG. 4 is a longitudinal sectional view of an example in which a discharge port is opened to an exhaust side seat of the other valve.

FIG. 5 is a longitudinal sectional view of a main part in which a flow passage is formed in a central shaft portion of a piston and an orifice is provided in the flow passage.

[Explanation of symbols]

 P ... Supply port A ... Load port R ... Exhaust port 1 ... Valve 2 ... Supply side seat 4 ... Supply valve section 6 ... Exhaust side seat 3 ... Exhaust valve section 22 ... Piston 23 ... Piston chamber 21 ... Inlet 24 ... Limit switch (Example of switch) 31 ... Discharge port 28 ... Flow path 32 ... Charge tank 33 ... Small diameter part 35 ... Coil spring 36 ... Housing 34 ... Spring receiver 38 ... Step part 41 ... Flow path 42 ... Orifice

Claims (4)

(57) [Claims] 1. A valve comprising a supply port, a load port, and an exhaust port, and two valves for inflow and shutoff from a supply port to a load port and from a load port to an exhaust port, which are arranged in parallel. It has a supply valve portion that sits on and separates from the side seat and an exhaust valve portion that sits on and separates from the exhaust side seat, and supplies compressed air that moves the piston to the left and right ends of the piston chamber that slides the piston. An electromagnetic switch that guides from the inlet port opened in the supply side sheet and generates a signal by moving the piston, and when the two valves are not synchronized, generates a signal in the switch by the difference in the detection pressure of the inlet port. A monitor for a solenoid valve, wherein the introduction port and the discharge port opened to the exhaust side sheet communicate with each other. 2. A valve comprising a supply port, a load port, and an exhaust port, and two valves for inflow and shutoff from a supply port to a load port, and from a load port to an exhaust port, are arranged in parallel. It has a supply valve portion that sits on and separates from the side seat and an exhaust valve portion that sits on and separates from the exhaust side seat, and supplies compressed air that moves the piston to the left and right ends of the piston chamber that slides the piston. An electromagnetic switch that guides from the inlet port opened in the supply side sheet and generates a signal by moving the piston, and when the two valves are not synchronized, generates a signal in the switch by the difference in the detection pressure of the inlet port. A valve monitor, wherein a charge tank is connected to a flow path connecting the inlet and the piston chamber. 3. A valve comprising a supply port, a load port, and an exhaust port, and two valves for inflow and shutoff from a supply port to a load port and from a load port to an exhaust port are arranged in parallel, and the valve is a supply valve. It has a supply valve portion that sits on and separates from the side seat and an exhaust valve portion that sits on and separates from the exhaust side seat, and supplies compressed air that moves the piston to the left and right ends of the piston chamber that slides the piston. An electromagnetic switch that guides from the inlet port opened in the supply side sheet and generates a signal by moving the piston, and when the two valves are not synchronized, generates a signal in the switch by the difference in the detection pressure of the inlet port. In the valve monitor, spring receivers are slidably provided on the small diameter portions at both ends of the piston, and a coil spring is contracted between the housing and the spring receiver. A solenoid valve monitor characterized in that the piston contacts the step formed on the housing in a neutral state of the piston. 4. A valve comprising a supply port, a load port, and an exhaust port, and two valves for inflow and shutoff from a supply port to a load port and from a load port to an exhaust port are arranged in parallel. It has a supply valve portion that sits on and separates from the side seat and an exhaust valve portion that sits on and separates from the exhaust side seat, and supplies compressed air that moves the piston to the left and right ends of the piston chamber that slides the piston. An electromagnetic switch that guides from the inlet port opened in the supply side sheet and generates a signal by moving the piston, and when the two valves are not synchronized, generates a signal in the switch by the difference in the detection pressure of the inlet port. A valve monitor, wherein a flow path penetrating the piston is provided, and an orifice is provided in the flow path.