JP2001173611A - Displacement sensor for hydraulic equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent hydraulic force from being given to a sensor main unit of low pressure resistance, decrease slide resistance of a moving member, and further attain compactness of a device and reduction of the number of part items. SOLUTION: A hydraulic chamber 4 and a core 2 are covered with a retainer 7 and a tube 1 and separated from a sensor main unit 3.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a displacement sensor for hydraulic equipment for detecting a displacement of a moving member of a hydraulic equipment such as a flow control valve. More specifically, the present invention relates to a displacement sensor for hydraulic equipment that can eliminate sliding resistance of a moving member and can prevent hydraulic pressure from being applied to a sensor body.

[0002]

2. Description of the Related Art A differential transformer type displacement sensor is widely used to detect displacement of a spool which is a moving member of a flow control valve.

FIG. 6 is a diagram showing a basic configuration of a differential transformer type displacement sensor.

In FIG. 6, it is assumed that the position of the center point S has changed from the reference position X0 by moving the core K along the X-axis direction. At this time, a difference occurs between the degree of magnetic coupling between the primary coil L3 and the secondary coil L1, and the degree of magnetic coupling between the primary coil L3 and the secondary coil L2. Here, when the primary coil L3 is excited, an induced electromotive force is generated in the secondary coils L1 and L2. Since the two secondary coils L1 and L2 are connected so that their polarities are opposite, an output voltage corresponding to the displacement of the core K can be obtained.
Thus, the displacement of the core K is detected.

FIG. 7 is a diagram showing a conventional technique using a differential transformer type displacement sensor.

A spool 30 is mounted on a valve body 32 of the flow control valve.
Is provided. The pressure oil in the spool 30 is the hydraulic chamber 22,
It is displaced by being supplied and discharged to 23. When the solenoid valve 20 is operated, the pressure oil is supplied to the hydraulic chamber 22 or 23.
Supplied to The core 31 of the differential transformer type displacement sensor 50 is connected to one end of the spool 30. The sensor flange 19 incorporates a primary coil and a secondary coil shown in FIG. The sensor flange 19 accommodates the core 31 therein and is mounted on the valve body 32.

In FIG. 7, when the solenoid valve 20 is operated, pressure oil is supplied to the hydraulic chamber 22 or 23 via the oil passage 21. As a result, the spool 30 moves.
When the spool 30 moves, the core 31 is displaced, and a voltage corresponding to the displacement of the core 31 is output from the sensor flange 19. The movement amount (movement position) of the spool 30 can be detected from the output voltage value.

[0008]

As shown in FIG. 7, in the prior art, a resin is used for the material of the sensor flange 19. This is to prevent the detected value of the displacement of the core 31 from being affected by magnetism.

However, the strength of the resin sensor flange 19 with respect to hydraulic pressure is lower than that of metal. When the sensor flange 19 having a low pressure resistance acts directly on the pressure oil as described above, the sensor flange 19 may be damaged.

In the prior art shown in FIG.
The entirety of the differential transformer type displacement sensor 50 is completely isolated from the hydraulic chambers 22 and 23 so that the pressure oil does not leak to the differential transformer type displacement sensor 50 side from the components 2 and 23. That is, the seal 27 is provided on the outer periphery of the spool 30 so that the pressure oil in the hydraulic chamber 23 does not leak to the differential transformer type displacement sensor 50 side. For this reason, the differential transformer type displacement sensor 50
Operates in an environment that does not act on pressurized oil. This prevents the pressure oil from acting on the sensor flange 19 and damaging it.

The seals 26 and 27 are provided on the outer periphery of the spool 30 and are in contact with the inner wall of the valve body 23. Therefore, when the spool 30 moves, the seals 26 and 27 slide on the inner wall of the valve main body 32, and sliding resistance occurs between the seals 26 and 27 and the inner wall of the valve main body 32.

When sliding resistance occurs between the seals 26 and 27 and the inner wall of the valve body 32, hysteresis occurs in the relationship between the amount of movement of the spool 30 and the pressure in the hydraulic chambers 22 and 23. That is, even if the same command is given to the spool 30, the movement position of the spool 30 shifts. Therefore spool 3
There is a problem that the controllability of 0 is deteriorated.

Further, in the prior art, since the entire structure of the differential transformer type displacement sensor 50 is completely isolated from the hydraulic chambers 22 and 23, the length of the device along the longitudinal direction of the spool 30 becomes large. There is a problem that the space is increased. Further, there is a problem that the number of parts increases.

An object of the present invention is to prevent hydraulic pressure from being applied to a sensor body having low pressure resistance, to reduce sliding resistance of a moving member, to further reduce the size of the apparatus, and to reduce the number of parts. I do.

[0015]

According to the present invention, there is provided a hydraulic device mounted on a hydraulic device provided with a moving member which is displaced by supplying hydraulic oil to a hydraulic chamber (4). (3), a displacement sensor connected to a moving member, and a sensor body accommodating the displacement member.
In a displacement sensor for hydraulic equipment that detects the displacement of the moving member by detecting the displacement of the displacement member,
A pressure vessel (60, 1,...) Covering the hydraulic chamber (4) and the displacement member so as to be isolated from the sensor body (3);
7) is provided.

The present invention will be specifically described with reference to FIG.

According to the present invention, the hydraulic chamber 4 and the core 2 are separated from the sensor body 3 by being covered with the retainer 7 and the tube 1. As a result, the pressure oil in the hydraulic chamber 4 does not directly act on the sensor body 3. Therefore, it is possible to prevent the hydraulic pressure from being applied to the sensor body 3 having low pressure resistance. Also, since the hydraulic chamber 4 and the core 2 are covered with the retainer 7 and the tube 1 to prevent leakage of pressurized oil,
There is no need to provide a seal around the moving member, such as the spool 5, which is a moving member and generates sliding resistance. Therefore, the sliding resistance of the spool 5 decreases. Further, the retainer 7 and the tube 1 are not separated from the hydraulic chamber 4 as in the prior art.
And a structure that isolates the core 2 of the sensor unit 15 from the sensor main body 3 of the sensor unit 15. For this reason, the length of the device along the longitudinal direction of the spool 5 can be reduced, and the device can be made more compact. Also, the number of parts can be reduced.

Therefore, according to the present invention, it is possible to prevent hydraulic pressure from being applied to the sensor body 3 having low pressure resistance, reduce the sliding resistance of the spool 5, further reduce the size of the apparatus, and reduce the number of parts. Reduction can be achieved.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a displacement sensor for hydraulic equipment according to the present invention will be described below with reference to the drawings.

FIG. 1A shows a hydraulic circuit diagram of the present embodiment. In this embodiment, a flow control valve is assumed as the hydraulic device.

As shown in FIG. 1A, the main pump 1
2 is driven by an engine (not shown) to discharge pressure oil and supply it to a flow control valve 13 which is a hydraulic device. The actuator 14 is configured so that the pressure oil discharged from the main pump 12
3 to be driven. The flow control valve 13 is a control valve that controls a flow amount and a direction of the pressure oil supplied to the actuator 14 by controlling a moving amount and a moving direction of the spool 5 that is a moving member.

The flow control valve 13 has a flow control valve body 6 and a sensor unit 15. The sensor section 15 is mounted on the flow control valve body 6. A spool 5 is provided inside the flow control valve body 6. Pilot pump 11
Discharges pressure oil for driving the spool 5. Sensor unit 15
Is a differential transformer type displacement sensor for detecting the moving position of the spool 5.

As shown in FIG. 1A, the sensor section 15 is mainly composed of a sensor supporting member 9 fixed to the flow control valve main body 6 and a sensor main body 3 fixed to the sensor supporting member 9. Become. The sensor support member 9 is fixed to the flow control valve body 6 via the retainer 7. The retainer 7 is connected to the tube 1 and as a whole a pressure vessel 60 (see FIG. 3)
Is composed. The hydraulic chamber 4 is formed by the retainer 7. The sensor support member 9 is formed with a pilot conduit 35 for guiding pressure oil discharged from the pilot pump 11 to the hydraulic chamber 4. The spool 5 is displaced by supplying pressure oil to the hydraulic chamber 4. In FIG. 1A, a pressure control valve provided between the pilot pump 11 and the hydraulic chamber 4 is omitted. Pressure oil having a size corresponding to a command value applied to the pressure control valve is supplied to the hydraulic chamber 4.

A core 2 as a displacement member is connected to one end of the spool 5 via a plug 34. The core 2 is housed inside the sensor body 3. When the core 2 is displaced, an induced electromotive force is generated in the coil 10 in the sensor body 3. The displacement of the spool 5 is detected by detecting the output voltage extracted from the sensor main body 3.

The hydraulic chamber 4 and the core 2 are covered with a retainer 7 and a tube 1 so as to be separated from the sensor body 3. For this reason, the pressure oil in the hydraulic chamber 4 stays in the retainer 7 and the tube 1 and acts on the core 2 but does not act on the sensor main body 3.

FIG. 1B is a view of the flow control valve 13 as viewed from an arrow A.

As shown in FIG. 1B, the sensor support member 9 is fixed to the flow control valve body 6 by support member fixing screws 33a and 33b. The sensor main body 3 is fixed to the sensor support member 9 by sensor fixing screws 8a and 8b.

FIG. 2 is an enlarged view of the sensor section 15 of FIG.

As shown in FIG. 2, the retainer 7 and the tube 1 are joined at a joint 16. The retainer 7 and the tube 1 are joined so that the core 2 can be inserted into the tube 1. For joining the retainer 7 and the tube 1, any joining means such as welding can be used. For example, retainer 7
And the tube 1 can be welded by brazing.
Further, the retainer 7 and the tube 1 may be formed integrally by, for example, press working. The material of the retainer 7 and the tube 1 is made of, for example, SUS. In particular, since the tube 1 faces the coil 10, it is necessary to use a non-magnetic material. As the material of the sensor main body 3, a resin for housing the coil 10 is used.

[0030] Seals 39 and 40 are provided between the retainer 7 and the sensor support member 3. These seals 3
9 and 40 prevent the pressure oil in the hydraulic chamber 4 from leaking to the outside.

FIG. 3 is a view showing a state in which the sensor section 15 is fixed to the flow control valve body 6, and is an exploded view of the sensor section 15.

As shown in FIG. 3, the plug 34 is connected to the spool 5 by screwing. The core 2 is connected to the plug 34 by screwing. The spool 5, the plug 34, and the core 2 may be integrally formed by, for example, shaving.

The pressure vessel 60 connecting the retainer 7 and the tube 1 is arranged at a position for accommodating the plug 34 and the core 2 connected to the spool 5.

Then, the retainer 7 of the pressure vessel 60 is fixed to the flow control valve main body 6 by fixing the sensor support member 9 to the flow control valve main body 6 with the support member fixing screws 33a and 33b.

Further, the sensor body 3 is fixed to the sensor fixing screw 8.
By fixing to the sensor support member 9 by a and 8b,
The core 2 in the tube 1 is housed in the sensor body 3.

Next, the operation of the first embodiment will be described with reference to FIG.

Now, the pilot pump 11 enters the hydraulic chamber 4 from the pilot pump 11 through the pilot line 35.
It is assumed that pressure oil is supplied via a pressure control valve (not shown) and the pilot line 35. At this time, the pressure oil supplied to the hydraulic chamber 4 is supplied to the seals 39 and 40 and the pressure vessel 6.
It is isolated from the sensor body 3 by 0,1,7.
Therefore, the pressure oil in the hydraulic chamber 4 does not act on the sensor body 3.
Therefore, no oil pressure is applied to the sensor body 3.

As described above, according to this embodiment, the hydraulic chamber 4
Further, since the core 2 is separated from the sensor main body 3 by covering the core 2 with the retainer 7 and the tube 1, it is possible to prevent hydraulic pressure from being applied to the sensor main body 3 having low pressure resistance.

When the pressure oil is supplied into the hydraulic chamber 4, the spool 5 moves to a position corresponding to the pressure of the pressure oil. Since the spool 5 is not provided with a seal to prevent pressure oil leakage,
The sliding resistance accompanying the movement of the spool 5 becomes very small. The core 2 is displaced in accordance with the movement of the spool 5, and an induced electromotive force is generated in the coil 10 in the sensor main body 3, and an output voltage is extracted from the sensor main body 3. The moving position of the spool 5 is detected from the output voltage taken out. Since the sliding resistance of the spool 5 is small, no hysteresis occurs in the spool 5. Therefore, the control of the flow control valve 13 can be performed with high accuracy.

As described above, according to the present embodiment, the hydraulic chamber 4
Further, since the pressure oil leakage is prevented by covering the core 2 with the retainer 7 and the tube 1, the sliding resistance of the spool 5 can be extremely reduced, and the controllability can be improved.

Further, according to the present embodiment, the retainer 7 and the tube 1 are provided in the sensor unit 15 instead of isolating the entire sensor unit 15 from the hydraulic chamber 4 as in the prior art. The core 2 and the sensor body 3 of the sensor unit 15 are configured to be isolated from each other. For this reason, the length of the device along the longitudinal direction of the spool 5 can be reduced, and the device can be made more compact. Also, the number of parts can be reduced.

In this embodiment, since no pressure is applied to the sensor main body 3, the bolts 8a for fixing the sensor main body 3,
8b can be reduced in diameter.

If the retainer 7 is attached to the flow control valve body 6 in a state where the central axis of the tube 1 is shifted from the central axis of the core 2, problems such as an increase in sliding resistance of each part may occur. is there.

Next, a second embodiment in which the center axis of the core 2 and the center axis of the tube 1 can be made coaxial with high precision will be described.

FIG. 4 is a view showing a second embodiment in which the center axis of the core 2 and the center axis of the tube 1 can be accurately made coaxial with each other. In FIG. 4, FIG.
(B), the same components as those in FIGS. 2 and 3 are denoted by the same reference numerals, and descriptions of these components will be omitted as appropriate.

The flow control valve body 37 shown in FIG. 4 has substantially the same structure as the flow control valve body 6 of the first embodiment. The sensor section 36 has substantially the same structure as the sensor section 15 of the first embodiment. However, the sensor unit 3 of the flow control valve body 37
A concave portion 37a is formed on the side where 6 is mounted. The concave portion 37a is formed on the peripheral edge of the end of the spool 5.

The retainer 17 has a projection 17a inserted into the recess 37a of the flow control valve body 37. The sensor support member 18 has a projection 18a that fits into the recess 37a of the flow control valve body 37 via the projection 17a of the retainer 17.
Are formed.

That is, the concave portion 37a of the flow control valve body 37
The sensor support member projection 18a is fitted together with the retainer projection 17a.

FIG. 5 shows that the sensor unit 36 is a flow control valve main body 37.
FIG. 4 is an exploded view of the sensor section 36, showing a state in which the sensor section 36 is fixed to the sensor section 36.

The pressure vessel 60 ′ connecting the retainer 17 and the tube 1 is arranged at a position for accommodating the plug 34 connected to the spool 5 and the core 2. The convex portion 17a of the retainer 17 is inserted into the concave portion 37a of the flow control valve main body 37.

The retainer 17 of the pressure vessel 60 'is fixed to the flow control valve main body 37 by fixing the sensor support member 18 to the flow control valve main body 37 with the support member fixing screws 33a and 33b. As a result, the sensor support member convex portion 18a is fitted into the concave portion 37a of the flow control valve main body 37 together with the retainer convex portion 17a.

Further, the sensor body 3 is connected to the sensor fixing screws 8.
The core 2 in the tube 1 is accommodated in the sensor main body 3 by being fixed to the sensor support member 18 by a and 8b.

As described above, according to the second embodiment, the retainer projection 17a is provided in the recess 37a of the flow control valve body 37.
At the same time, the retainer 17 can be accurately positioned by fitting the convex portion 18a of the sensor support member.
Thereby, a deviation between the central axis of the core 2 and the central axis of the tube 1 can be eliminated and the coaxial C can be obtained.

In the embodiment described above, the case where the displacement of the spool of the flow control valve is detected has been described. However, the present invention can be applied to any hydraulic device that is operated by pressurized oil. In the present embodiment, the description has been made assuming a differential transformer type displacement sensor as the displacement sensor. However, the present invention can be applied to any displacement sensor as long as the displacement member detects displacement by displacing the inside of the sensor.

[Brief description of the drawings]

FIG. 1 is a hydraulic circuit diagram showing a first embodiment of a displacement sensor for hydraulic equipment according to the present invention.

FIG. 2 is an enlarged view of a sensor unit of FIG. 1;

FIG. 3 is an exploded view of the sensor unit of FIG. 1;

FIG. 4 is a view showing a second embodiment different from FIG. 1;

FIG. 5 is an exploded view of the sensor unit of FIG.

FIG. 6 is a diagram illustrating a basic configuration of a differential transformer type displacement sensor.

FIG. 7 is a diagram showing a conventional technique.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Tube 2 ... Core 3 ... Sensor flange 4 ... Hydraulic chamber 5 ... Spool 13 ... Flow control valve

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Naoki Ishizaki 400, Yokokura Nitta 400, Oyama City, Tochigi Prefecture Inside Koyama Factory, Oyama Plant (72) Inventor Yuichi Yamamoto 400, Yokokura Nitta, Oyama City, Tochigi Prefecture Koyama Factory, Oyama Plant F-term (reference) 3H002 BA01 BB02 BD04 3H081 GG12 GG22

Claims (1)

[Claims] A displacement sensor for a hydraulic device to be mounted on a hydraulic device provided with a moving member that is displaced by supply of pressure oil to a hydraulic chamber (4), the displacement sensor being connected to the moving member. , Sensor body housing displacement member (3)
A displacement sensor for a hydraulic device that detects displacement of a moving member by detecting displacement of a displacement member, wherein the hydraulic chamber (4) and the displacement member are covered so as to be isolated from the sensor body (3). , Pressure vessel (60, 1,
7) A displacement sensor for hydraulic equipment, wherein the displacement sensor is provided.