KR100378436B1 - Pilot operated directional control valve having position detecting function - Google Patents

Abstract

A pilot switching valve having a position detection function capable of detecting an operating position of the valve member via a piston for driving the valve member is obtained.

The magnet 21 for position detection is provided in the part located in the breathing chamber 9 side which was isolated from the pilot pressure chamber 13a of the piston 12a which contacts the one end of the spool 6, and the said magnet 21 The magnetic sensor 22 which detects the magnetism from the said magnet 21 is provided in the casing 4 part corresponding to this.

Description

Pilot Switching Valve with Position Detection

The present invention relates to a pilot type switching valve having a position detection function that can detect an operation position of a valve member such as a spool using a magnet.

Pilot-type switching valves capable of monitoring the switching operation of the spool using magnets are already known, for example, as disclosed in Japanese Unexamined Patent Publication No. 7-31021. These switching valves are provided with pistons for receiving pilot fluid pressure at both ends of the spool, respectively, and the magnet is installed at one piston by switching the spool by the pilot fluid pressure acting on these pistons, and the magnet of the casing A detection coil for detecting a change in the magnetic flux at a position corresponding to the position of the magnetic flux, and moving the piston, that is, the spool moving speed from the magnitude of the induced voltage generated in the detection coil by the change in the magnetic flux when the magnet moves with the piston. Detect and determine if it is normal.

However, the conventional switching valve is provided at a position where the magnet is exposed in the pressure chamber of the piston cross section, so that the magnet is in direct contact with the pilot fluid, and the pilot fluid contains water, chemical mist, or metal. When magnetic particles such as powders are contained, they are likely to cause problems such as rust, corrosion, and adsorption of fine particles by contact with them, and are likely to cause a decrease in detection accuracy or a sliding failure due to a decrease in magnetic force. There was a flaw.

In addition, the switching valve generates an induced voltage in the detection coil by the change of the magnetic flux according to the movement of the magnet, detects the moving speed of the spool from the magnitude of the induced voltage, and determines whether the moving speed is normal. The operating position of could not be detected.

The main technical problem of the present invention is to provide a pilot switching valve having a position detection function capable of detecting an operating position of the valve member via a piston for driving the valve member.

Another technical problem of the present invention corresponds to installing a position detecting magnet on a piston in the switching valve, and prevents the magnet from contacting the pilot fluid so as not to be influenced by the pilot fluid, and to provide stable detection accuracy. And to maintain operating characteristics.

1 is a cross-sectional view showing a first embodiment of a switching valve according to the present invention.

FIG. 2 is an enlarged view of a main part of FIG. 1.

3 is a partial schematic cross-sectional view showing a second embodiment of a switching valve according to the present invention.

4 is an enlarged view of a main part of FIG. 3.

5 is an enlarged cross-sectional view of the main part of FIG.

(Explanation of the sign)

P, E1, E2, A, B... Ports 2, 2a, 2b... Pilot valve

4… Casing 5... Valve hole

6... Spool 8.. End sealing member

9... Breathing chambers 11a, 11b. Piston seal

12a, 12b... Piston 13a, 13b... Pressure chamber

20... Position detecting mechanism 21. Magnet

22... Magnetic sensor 31.. Accommodation

In order to solve the above problems, according to the switching valve of the present invention, a magnet for position detection is provided in a piston provided at one end of the valve member, and a magnetic sensor for detecting magnetism from the magnet is provided in a casing portion corresponding to the magnet. Is installed. The position on the piston in which the magnet is installed is the part of the respiratory chamber side partitioned between the valve member end face on one side of the piston. This breathing chamber is hermetically isolated from the pilot pressure chamber on the opposite side of the piston by the piston packing of the outer periphery of the piston, so that the pilot fluid does not flow in.

In the switching valve of the present invention having the above structure, the piston is driven by the pilot fluid supplied to the pilot pressure chamber, and the valve member is switched via the piston. The magnetic flux density from the magnet moving together with the piston is detected by the magnetic sensor, and the operating position of the piston, that is, the operating position of the valve member, is detected by the change of the magnetic flux density according to the movement of the magnet.

Here, since the magnet is installed at the position of the piston's breathing chamber side, the magnet is not in direct contact with the pilot fluid. Therefore, the magnet is rusted even if the pilot body contains moisture, chemical mist, or magnetic particles such as metal powder. Or corrosion and adsorption of fine particles can maintain a stable performance without causing magnetic degradation or malfunction caused by the adsorbed fine particles.

According to one specific embodiment of the present invention, the magnet is provided on the outer circumference of the piston, and the magnetic sensor is provided on the portion near the outer circumference of the piston in the casing.

According to another specific embodiment of the present invention, an accommodating chamber is formed on an opposing surface of the piston with a valve member, and the magnet is provided in the accommodating chamber so as to be located close to the hydraulic pressure surface of the piston. The magnetic sensor is provided at a position facing the hydraulic pressure surface.

According to another specific embodiment of the present invention, the switching valve is a double pilot type switching valve having two pistons and two pilot valves, in which two pilot valves are intensively installed at one end of the casing, and the other end side of the casing. The magnet and the magnetic sensor are installed at one piston and the casing.

In the present invention, a piston having at least a magnet can be connected to the valve member.

In the present invention, the magnetic sensor is preferably configured to detect the magnetism from the magnet in the entire stroke of the piston so that the entire operating position of the piston can be detected from the change in magnetic flux density due to the variation of the magnet. .

Accordingly, not only the position of the piston, that is, the position of the stroke end of the valve member, but also the position in the middle of the stroke can be determined from the relationship between the position of the valve member from the start of the stroke to the end of the stroke and the operation time. It is possible to easily determine such a thing by a discrimination circuit, and as a result, preventive measures can be prevented before failure, thereby preventing a prolonged shutdown of the work system due to a failure or an accident.

1 shows a first embodiment of a switching valve according to the invention, wherein the switching valve illustrated here is a single pilot switching valve for switching the main valve 1 with one pilot valve 2.

The main valve 1 has a configuration as a five-port valve, and includes a casing 4 made of a nonmagnetic material. The casing 4 has a first member 4a having a rectangular parallelepiped shape, a second member 4b which is connected to one end thereof and serves as an adapter for installing the pilot valve 2, and is connected to the other end as an end cover. It consists of the 3rd member 4c which functions.

Supply ports P and two discharge ports E1 and E2 are provided on one of the upper and lower surfaces of the first member 4a, and two output ports A and B are provided on the other side thereof. Inside the first member 4a, a valve hole 5 in which these ports are opened side by side in the axial direction is provided, and in this valve hole 5, a spool 6 made of a nonmagnetic material which is a valve member for flow switching. This is slidably accommodated.

The outer periphery of the spool 6 is provided with a plurality of sealing members 7 for mutually partitioning the flow paths connecting the respective ports, and the end of the spool 6 on the outer periphery of both ends of the spool 6 End sealing members 8 are provided, respectively, which face between the breathing chamber 9 and the flow path of the working fluid in the valve hole 5 facing each other. Reference numeral 10 in the figure is a guide ring for stabilizing the sliding of the spool (6).

On the other hand, the piston chambers 11a and 11b are formed in the said 2nd member 4b and the 3rd member 4c in the position which both ends of the spool 6 face, respectively. The first piston chamber 11a formed in the second member 4b has a large diameter, and a large diameter first piston 12a is slidably accommodated in the center thereof, and one third member 4c is provided in one of the third members 4c. The formed second piston chamber 11b has a diameter smaller than that of the first piston chamber 11a, and a second piston 12b having a small diameter is slidably accommodated therein. These pistons 12a and 12b are respectively in contact with the cross section of the spool 6 as represented by the second piston 12b or integrally with the spool 6 as represented by the first piston 12a. It is connected and is made to move in synchronism with the said spool 6. In the case of connecting the piston to the spool 6, in the illustrated example, the hook 14a provided on the piston 12a is coupled to the engaging groove 14b of the outer circumference of the spool 6, but the connection method is separately It is not limited.

First and second pressure chambers 13a and 13b are formed on the rear side of each of the pistons 12a and 12b, that is, on the part opposite to the surface in contact with the spool 6, and each piston 12a. Between the pressure chambers 13a and 13b and the breathing chambers 9 and 9, respectively, is formed between the 12b and the spool 6, respectively. It is airtightly cut off by the piston packings 15 and 15 provided on the outer periphery of 12b).

In addition, the first pressure chamber 13a located on the side of the first piston 12a having a large diameter is controlled by the pilot flow paths 16a and 16b via the manual operation mechanism 17 and the pilot valve 2. The second pressure chamber 13b, which is in communication with the supply port P and located on the side of the second piston 12b of small diameter, is always in communication with the supply port P through the pilot flow passage 16c.

When the pilot valve 2 is in the off state and no pilot fluid is supplied to the first pressure chamber 13a, the second piston 12b is driven by the pilot fluid pressure supplied to the second pressure chamber 13b. ), The spool 6 is in the first switching position moved to the left as shown in FIG. In this state, when the pilot valve 2 is turned on and the pilot fluid is supplied to the first pressure chamber 13a, the pilot valve 2 acts on the first piston 12a by the difference in the hydraulic pressure areas of the two pistons 12a and 12b. Since the hydraulic pressure acting force is larger than the hydraulic pressure acting on the second piston 12b, the spool 6 is pushed to the right of the first piston 12a to move to the right, and switches to the second switching position.

In addition, the manual operation mechanism 17 directly connects the pilot flow paths 16a and 16b by pressing the operator 17a so that the first pressure chamber 13a communicates with the supply port P. Is the same as when the pilot valve 2 is turned on.

The pilot valve 2 is an electronically operated pilot valve that opens and closes the pilot flow path by energizing the solenoid. Since its structure and operation are the same as those of the known ones, the detailed description thereof will be omitted.

The switching valve is provided with a position detecting mechanism 20 for detecting an operating position of the spool 6. As can be seen from Fig. 2, the position detecting mechanism 20 is provided on the magnet 21 and the casing 4 side of one of the pistons (the first piston 12a in the illustrated example) and the magnet ( It consists of a magnetic sensor 22 that detects the magnetism from 21. The magnetic sensor 22 detects a change in the magnetic flux density when the magnet 21 moves together with the piston 12a, and increases and decreases the piston. (12a) That is, the operation position of the spool 6 is detected.

The magnet 21 is formed in a ring shape having a notch in a portion of the circumference by mixing magnetic metal powder in a soft elastic base such as synthetic resin or synthetic rubber. The outer circumference of the piston 12a, piston packing ( It is provided in the position closer to the breathing chamber 9 side than 15). That is, it is provided in the above-mentioned position by inserting the said ring-shaped magnet 21 in the state which elastically enlarged the diameter in the installation groove 23 formed in the outer periphery of the piston 12a.

In this case, the thickness of the magnet 21 is slightly smaller than the depth of the mounting groove 23, so that the outer circumferential surface of the magnet 21 is lower than the outer circumferential surface of the piston 12a, thereby sliding on the outer circumferential surface of the piston chamber 11b. It is preferable not to contact, and accordingly, the sliding resistance of the piston 12a due to the sliding contact of the magnet 21 can be prevented from being increased, and the magnet 21 also slightly reduces the magnetic fine particles in the atmosphere. Even if it adsorbs, it can prevent that it adversely affects the sliding of the piston 12a.

In addition, the magnet 21 can be prevented from coming into direct contact with the pilot fluid by providing the magnet 21 at a position on the side of the breathing chamber 9 on the outer periphery of the piston 12a. Even if magnetic particles such as chemical mist or metal powder are contained, the magnet 21 does not rust, corrode or adsorb magnetic particles by contacting them, and deterioration of position detection accuracy or adsorption caused by a decrease in magnetic force. The malfunction of the piston 12a due to the fine particles does not occur.

On the other hand, the magnetic sensor 22 is adapted to detect the magnetism from the magnet 21 in the entire chamber of the spool 6 in the storage chamber 25 formed in the second member 4b of the casing 4. It is provided in close proximity to the magnet 21. That is, the magnetic sensor 22 detects the maximum magnetic flux density closest to the magnet 21 when the piston 12a is at either stroke end, and the piston 12a is at the other stroke end. In this case, the magnet 21 is provided at a position apart from the magnet 21 to detect the minimum magnetic flux density.

The magnetic sensor 22 is connected to a discrimination circuit (not shown) via the lead wire 26, and outputs a detection signal according to the magnetic flux density to the discrimination circuit. In this discriminating circuit, data necessary for position detection, such as the relationship between the respective operating positions, magnetic flux densities, operating times, and fluid pressures when the piston 12a (hence the spool 6) operates normally, is input in advance. When the detection signal from the magnetic sensor 22 is input, the position of both stroke ends of the piston 12a, each position during stroke, etc. are measured based on the said data, and the piston 12a from stroke start to stroke end is measured. From the relationship between the position and the operation time, it is possible to determine whether the operation of the piston 12a (and hence the spool 6) is normal or not. As a result, it is possible to detect the preceding signal before failure and preventive measures, and to prevent the situation such as stopping the operation of the device for a long time due to the occurrence of a failure or an accident.

In addition, the detected position of the piston 12a, an operating time, etc. can be displayed on a display apparatus in numerical value, a graph, etc.

In the above embodiment, one magnetic sensor 22 is provided, but two magnetic sensors may be provided at positions opposite to the magnets 21 at both stroke ends of the piston 12a, respectively. In this case, when the piston 12a is at one stroke end, one magnetic sensor detects the maximum magnetic flux density, the other magnetic sensor detects the minimum magnetic flux density, and on the other side of the piston 12a In the case of the stroke end, the operating position of the spool 6 can be known from the relationship of the change in magnetic flux density detected by the two magnetic sensors by setting the positional relationship between the two magnetic sensors and the magnet so as to be reversed.

In addition, although the magnet 21 is provided in the outer periphery of the piston 12a in the said Example, it can also be provided in another place of a piston. In Fig. 3, a second embodiment of the present invention, in which a magnet is installed, is representatively shown by a double pilot valve having two pilot valves.

The switching valve of this second embodiment is provided with two pilot valves 2a and 2b and two manual operation mechanisms 17a and 17b so that the two pilot valves 2a and 2b are connected to one end of the casing 4 [ On the first piston 12a side]. In addition, the two pistons 12a and 12b have the same size as each other and are not integrally connected to the spool 6, but are in contact with the end face of the spool 6. The first pressure chamber 13a communicates with the supply port P via the pilot flow paths 30a and 30b via the first pilot valve 2a and the first manual operation mechanism 17a. The seal 13b communicates with the supply port P via the pilot flow paths 30a and 30c via the second pilot valve 2b and the second manual operation mechanism 17b.

The switching valve drives two pistons 12a and 12b by alternately supplying pilot fluid to the first pressure chamber 13a and the second pressure chamber 13b to the two pilot valves 2a and 2b. 6).

In the switching valve, the position detecting mechanism 20 is provided on the side of the second piston 12b on the side opposite to the side on which the two pilot valves 2a and 2b are provided.

That is, as can be seen from FIG. 4 and FIG. 5, the second piston 12b is formed with an accommodating chamber 31 extending in the axial direction from the contact surface side with the spool 6 toward the hydraulic pressure surface. The magnet 21 is provided in the inner bottom of the seal 31 so as to be located close to the pressure receiving surface. On the other hand, the third member 4c of the casing 4 is located from the lower surface side of the second member 4b toward the upper surface side at a position on the rear surface side of the wall surface portion facing the hydraulic pressure surface of the second piston 12b. An installation groove 32 is formed, and the magnetic sensor 22 is inserted into this installation groove 32 and is fixed with the screw 33.

The magnetic sensor 22 detects a change in magnetic flux density when the magnet 21 approaches or moves away from the magnetic sensor 22 due to the movement of the second piston 12b.

Structures, functions or preferred modifications and the like of the second embodiment are substantially the same as those in the first embodiment, and their description is omitted.

As described above, the position detection mechanism 20 in each of the above embodiments is not a system for detecting the entire operating position of the spool 6 from the change of the magnetic flux density caused by the movement of the piston. The magnetic sensor may be turned on and off at both stroke ends, so that only the stroke ends of the spool 6 may be detected.

In the first embodiment, a single pilot switching valve having two pistons 12a and 12b is shown, but a return spring is provided instead of a small diameter second piston 12b. Naturally, the spring return type may be a spring return type which deflects the spool 6 at all times by the deflection force of the spring.

As described above, according to the present invention, by providing the position detecting magnet to the piston, the operation position of the valve member can be detected through the piston. In addition, since the magnet is prevented from coming into contact with the pilot fluid by installing the magnet at a portion located on the side of the respiratory chamber of the piston, even if magnetic particles such as moisture, chemical mist or metal powder are contained in the pilot fluid. In order to maintain stable performance without causing the magnet to rust, corrode, or adsorb magnetic particles in contact with them, deterioration in position detection accuracy due to a decrease in magnetic force, malfunction of the piston due to adsorbed fine particles, etc. Can be.

Claims (6)

With multiple ports: A valve hole through which each port opens; A casing having the port and the valve hole; A flow path switching valve member slidably received in the valve hole; A piston chamber formed on at least one end side of the valve member; A piston slidably received in the piston chamber, the piston being operated by the action of a pilot fluid pressure to switch the valve member; A breathing chamber that is partitioned between the piston and the valve member to open to the outside; An end sealing member provided at an end circumference of the valve member and blocking between the working fluid flow path in the valve hole and the breathing chamber; A piston packing installed at an outer circumference of the piston and blocking between a pilot pressure chamber at one side of the piston and the breathing chamber; A magnet which is shifted together with the piston attached to a portion located on the respiratory chamber side of the piston packing of one piston; At least one magnetic sensor provided at a position proximate the magnet in the casing and detecting magnetism from the magnet; And a pilot valve for supplying a pilot fluid to the pilot pressure chamber. The pilot type switching valve having a position detection function according to claim 1, wherein the magnet is provided on an outer circumference of the piston and the magnetic sensor is provided on a portion of the casing close to the outer circumference of the piston chamber. . The pressure receiving surface according to claim 1, wherein a housing chamber is formed on an opposing surface of the piston with the valve member, and the magnet is provided so as to be located close to the hydraulic pressure surface of the piston. Pilot type switching valve having a position detection function, characterized in that the magnetic sensor is installed in a position opposite to. 4. The switching valve according to claim 3, wherein the switching valve is a double pilot switching valve having two pistons and two pilot valves, the two pilot valves being concentrated at one end of the casing and one side at the other end of the casing. A pilot switching valve having a position detection function, characterized in that the magnet and the magnetic sensor are installed on the piston and the casing. The pilot type switching valve according to claim 1, wherein the piston having the magnet and the valve member are integrally connected to each other. 2. The magnetic sensor as set forth in claim 1, wherein the magnetic sensor is configured to detect magnetism from the magnet in the entire stroke of the piston, and is configured to detect the entire operating position of the piston from a change in magnetic flux density due to the change of the magnet. Pilot type switching valve with position detection function.