KR20030095200A - Valve stroke sensor - Google Patents

Abstract

Provided is a valve stroke sensor that absorbs core misalignment of the spool and stroke detection unit, is easy to process and assemble, and has high detection accuracy.

Valve stroke sensor that detects the stroke amount of the spool. The valve stroke sensor is fixed to the spool end of the valve and strokes along with the spool, the to-be-detected body is arranged to cover the outside of the to-be-detected body, and a stroke detection unit for outputting a signal according to the stroke amount of the to-be-detected body, and core misalignment. It is made by providing a core shift absorbing means for absorbing.

Description

VALVE STROKE SENSOR

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a valve stroke sensor, and more particularly, to a valve stroke sensor used for detecting a valve movement amount, correcting a valve movement amount, or controlling a variable displacement pump or engine.

In general, an actuator is often used in a hydraulic circuit, and pressure supply and discharge of hydraulic oil for controlling the operation of the actuator is performed by a valve. The valve generally controls the operation of the actuator by changing the direction in which the pressurized oil flows by inserting the spool hermetically into the valve main body and by stoking the spool from the neutral position. Since this valve is equipped with a stroke sensor and measures the stroke amount, the flow rate or the differential pressure flowing through the spool is detected and used for the control of the hydraulic equipment.

The stroke sensor attached to the valve has a rod attached to the end of the spool, and a core is attached thereto, and a stroke detection unit covering the outside of the core is attached to the side surface of the valve body on the spool end side. When the valve is operated and the spool strokes, the stroke sensor measures the position of the core and the measurement signal is output as the position of the spool.

As a prior art of such a stroke sensor, the position detector of the valve apparatus is proposed by Unexamined-Japanese-Patent No. 9-303327. According to the publication, as shown in Fig. 4, the position detector 60, which is a stroke sensor, is provided through the cover 62 and the mounting bolt 63 attached to the side position of the valve body 61.

The mounting bolt 63 has a shaft hole in the center thereof, is fitted to a part of the outer circumference of the inner pipe 66 fitted inside the stroke detection unit 65, and is fixed at the end of the stroke detection unit 65. In addition, a male screw is screwed into the female screw of the mounting hole provided on the valve body side in the shaft portion of the mounting bolt 63, and the seal ring 67 is fitted into the circumferential groove provided on the outer peripheral portion thereof.

With the above configuration, when the zero point adjustment of the output is performed, the position detector 60 loosens the fixing nut 68 and makes the installation nut 63 rotatable with respect to the installation hole. Turn to adjust the screw insertion amount. Thereby, the zero point of the output voltage from the stroke detection part 65 with respect to the core 69 can be adjusted.

At the time of adjustment, since the output voltage of the stroke detection part 65 can be adjusted while actually checking, zero point adjustment can be easily performed in a short time. In addition, since the sealing nut 67 is sealed between the fixing nut 68 and the mounting bolt 63, it is described that oil in the valve body does not leak during the adjusting operation.

In order to reduce the power supply and improve the detection accuracy, the position detector needs to reliably detect the position of the core by reducing the gap between the stoke detecting unit and the core. However, in Japanese Unexamined Patent Application Publication No. 9-303327, although the spool is slidably supported by the valve body, core displacement occurs between the spool and the position detector because the position detector is attached by attaching a cover to the side position of the valve body. It becomes easy and it is difficult to make a clearance small.

This core shift is caused by, for example, the position shift between the valve body and the cover and the inclination of the screw hole for screwing the core drilled into the spool. In particular, since the core is formed integrally with the long rod, it is necessary to make the screw hole inclined with high accuracy, but it is difficult to obtain the precision. This position detector has a large core shift at the tip due to the coaxiality of the screw hole of the spool and the inclination of the screw hole, and easily causes a core shift between the core attached to the spool and the position detection unit, and has a large gap. There is a need.

In this position detector, if the gap is made small, the core and the inside of the inner pipe may interfere with parts, or the core may be damaged. If the gap is made larger, the detection accuracy is lowered and the function of the position detector is lowered. The problem arises.

In order to prevent this, it is necessary to use a positioning pin between the valve body and the cover, and to reduce core coordination by reducing the coaxiality of the spool and the inclination of the screw hole, but the cost is high and the number of assembly steps The problem arises that there are many. In addition, even when the valve body and the cover are aligned at the time of assembly, core shift may occur due to vibration or the like at the time of use, and the above problem also occurs.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and an object of the present invention is to provide a valve stroke sensor that absorbs core shift between the spool and the stroke detection unit, in particular, facilitates processing and assembly, and has a high detection accuracy. It is done.

1 is a side sectional view of a valve stroke sensor according to the first embodiment of the present invention.

2 is a side sectional view of a first valve stroke sensor of a second embodiment according to the present invention.

3 is a side sectional view of a second valve stroke sensor of a third embodiment according to the present invention.

4 is a side sectional view of a conventional position detector.

(Explanation of symbols for the main parts of the drawing)

One … Valve stroke sensor 1A. 1st valve stroke sensor

1B. Second valve stroke sensor 2. Valve body

3…. Spool 4,21... Mounting bolt

5…. Cover 6. sleeve

7. Retainer 9... Cap nut

10... Stroke detection section 11. Stroke detector

12... Detected object 12A... First detected object

12B. Second detected object 22... H-shaped seam

25…. First spring 26... Spring receptacle

Dm… Core shift absorbing means

In order to achieve the above object, the invention of the valve stroke sensor according to the present invention is a valve stroke sensor, which is attached to the spool end of the valve and arranged so as to cover the outside of the to-be-detected body and the to-be-detected body. And a stroke detection section for outputting a signal corresponding to the stroke amount of the object to be detected, and a core displacement absorbing means for absorbing the core displacement.

The stroke detection unit may be provided by supporting means for supporting the detected object concentrically.

Further, the core displacement absorbing means covers the parallel portion of the object to be detected and has a thread portion formed at one end of the spool, a parallel portion of the object to be installed on the spool side, and a gap allowing the core deviation. It may be made of a cap nut that is screwed together.

The zero point may be adjusted by moving in the axial direction.

According to the above configuration, the valve stroke sensor is adapted to absorb the core deviation by providing a core displacement absorbing means so that the detected object and the stroke detection portion are coaxial even if a core displacement occurs in the spool and the stroke detection portion. For this reason, even if the clearance between the to-be-detected body and the stroke detection part is made small, the valve stroke sensor does not cause interference, there is no damage, etc., and the detection accuracy is improved.

Since only the core shift absorbing water is provided between the spool and the to-be-detected part of the stroke detection part, there is no need to improve the coaxiality between the spool and the stroke detection part, and the spool and the stroke detection part can be made cheap. In addition, since the spool and the stroke detection unit are connected by the core shift absorbing means, the assembly becomes easy.

Since the stroke detection unit is provided with support means for supporting the object to be detected concentrically, the coaxiality can be secured simply by inserting the object to be detected into the stroke detection unit, and the gap can be made small without interference, thereby detecting the object to be detected. Improve precision

Since the to-be-detected body is attached to the threaded portion of the spool by the cap nut with a gap allowing the core shift, the core shift is absorbed only by attaching the stroke detection portion to the cover to connect the spool and the stoke detection portion. As a result, there is no need to improve the part precision, the parts can be made cheap, and the assembly is easy.

EMBODIMENT OF THE INVENTION Hereinafter, the Example of the valve stroke sensor which concerns on this invention is described with reference to drawings.

First, the valve stroke sensor of the first embodiment will be described with reference to FIG. 1 is a side sectional view of a valve stroke sensor 1 as a first embodiment.

In FIG. 1, the valve stroke sensor 1 mainly includes the valve body 2, the spool 3, the mounting bolt 4, the cover 5, the sleeve 6, the spring 7, and the retainer 8. ), The cap nut 9 and the stroke detection unit 10.

The spool hole 2a is drilled in the valve body 2, and the spool 3 is slidably inserted in the spool hole 2a so as to be slidable. The screw hole 3 is drilled in the spool 3 on the shaft center, and the mounting bolt 4 is screwed into the screw hole 3a. The mounting bolt 4 has one end screw 4a screwed into the screw hole 3a at one end or the other end screw 4b at the other end. The end surface 4c of the other end side screw 4b is formed flat. The other end side screw 4b may be provided on the spool 3 to integrally install the spool 3 and the mounting bolt 4.

The cover 5 is attached to one end side of the valve body 2 on which one end of the spool 3 protrudes, and has a bottomed hole 5a for accommodating the spring 7, the retainer 8, and the like therein. ) Is formed. The cover 5 is attached to the valve body 2 by the bolt which is not shown in figure. The bottomed hole 5a is provided with a threaded hole 5b for the sleeve to which the sleeve 6 is screwed.

The sleeve 6 has a male screw 6a which is screwed to the cover 5 at its outer circumference and a hollow hole with a step inside thereof, and is formed therein to slidably support the detected object 12. One hole 6b and a second hole 6c are provided.

In the center portion of the sleeve 6, a third hole 6e into which the outer diameter portion of the stroke detection portion 10 is inserted is drilled. The first hole 6b, the second hole 6c, and the third hole 6e are drilled with a predetermined coaxiality, so that the interference between the detected object 12 and the stroke detection unit 10 is reduced. This eliminates work and improves detection accuracy. On the other end side of the sleeve 6, a 6 d screw hole for a detector through which the stroke detection part 10 is screwed is drilled.

The spring 7 is supported by the valve main body 2 via the retainer 8 and the other end contacting the cover 5 via the retainer 8, and holds the spool 3 in the neutral position. The spool 3 strokes left and right against the spring 7 to operate and supply the fluid from the pressure source to the actuator, and this stroke is detected by the stroke detection unit 10.

The cap nut 9 is screwed to the mounting bolt 4 with the to-be-detected body 12 fitted. The inner side 9a of the cap nut 9 is provided with a clearance Cr allowing the core shift between the spool 3 and the stroke detection unit 10 at right angles to the shaft center. In addition, the cap nut 9 and the mounting bolt 4 sandwich the parallel portion 12a of the object to be detected 12 with a very small gap in the axial direction, and the object to be detected 12 is about the shaft center. It is movable in a perpendicular direction.

The very small gap in the axial direction between the cap nut 9 and the mounting bolt 4 is adjusted by screwing the cap nut 9 and the mounting bolt 4 so as to have a dimension slightly thicker than the parallel portion 12a. Alternatively, a spacer slightly thicker than the parallel portion 12a may be inserted between the cap nut 9 and the mounting bolt 4 to adjust the spacer.

The stroke detection part 10 is comprised by the stroke detector 11 and the to-be-detected body 12. As shown in FIG. The stroke detector 11 extracts a signal proportional to the stroke of the to-be-detected body 12 using a non-contact differential transformer, for example, detects the stroke amount of the spool 3, and outputs it as an electric signal.

The stroke detector 11 is attached by screwing the case 11a to the sleeve 6 with a male screw 6a, while the sleeve 6 is screwed into the sleeve screw hole 5b of the cover 5. It is.

As for the case 11a, the front-end | tip of the outer peripheral part is inserted in the 3rd hole 6e of the sleeve 6, and the stroke detector 11 is the 1st hole 6b which is a guide of the to-be-detected body 12, and Coaxiality of the two holes 6c is obtained.

As a result, the stroke detector 11 is inserted into the sleeve 6 so that the to-be-detected body 12 is easily allowed to be installed in the stroke detector 11, and the stroke detector 11 and the to-be-detected body 12 are provided. The cylindrical portion 12b is stuck with a small predetermined gap.

In the stroke detector 11, the male screw 11b of the case 11a is movably attached to the detector screw hole 6d of the sleeve 6, and the zero point of the voltage at the neutral position is adjustable by the movement. . The stroke detector 11 is fastened to the sleeve 6 by means of a nut 14 after adjustment.

The stroke detector 11 is protected by a sealing member, a container, or the like so that fluid does not enter from the bottomed hole 5a side of the cover 5. The stroke detector 11 may be any sensor such as a sensor capable of detecting a displacement amount such as a potentiometer regardless of contact or non-contact type.

The to-be-detected body 12 is formed by the parallel part 12a in the one end on the side of the spool 3, the cylindrical part 12b in the other end side, and the rod part 12c, 12d with the step difference between them. It is. The parallel portion 12a is fitted into the flat end surface 4c and the cap nut 9 of the mounting bolt 4 screwed into the screw hole 3a formed at one end of the spool 3, and is movable in the direction perpendicular to the axial center. Is attached.

The large diameter rod portion 12c of the rod portion is hermetically inserted and slidably supported in the first hole 6b of the sleeve 6, and the small diameter rod portion 12d is inserted into the second hole 6c of the sleeve 6. It is. The cylinder 12b is housed inside the stroke detector 11 as a core, and the stroke position is detected by the stroke detector 11.

Since the rod 12c and 12d are hermetically inserted and slidably supported in the first hole 6b and the second hole 6c, the cylindrical portion 12b of the tip portion is stroked. The gap with the detector 11 can be made small.

In addition, since the parallel part 12a by the side of the spool 3 is fitted so that the parallel part 12a on the spool 3 side is movable so that it may move to an axial center perpendicular direction by the cap nut 9, even if core shift | deviation with respect to the spool 3 arises, The body 12 to be detected is accommodated in the stroke detection unit 10 while moving in the axial center perpendicular direction.

Thus, the to-be-detected body 12 can be easily inserted in the predetermined position of the stroke detector 11, and the to-be-detected body 12 becomes a core which moves integrally with the spool 3, and the stroke The position is detected by the stroke detector 11 (differential transformer).

In the above configuration, an example of assembling will be described next. Screw the mounting bolt (4) into the screw hole (3a) of the spool (3). The flat end surface 4c of the mounting bolt 4 is brought into contact with the end surface of the parallel portion 12a of the object to be detected 12, and the parallel portion 12a is covered by the cap nut 9 to detect the object. Attach (12) to the mounting bolt (4).

At this time, the parallel part 12a is fitted with the clearance Cr which can be moved by the cap nut 9 and the installation bolt 4 at right angles to an axial center. Thus, the to-be-detected body 12 is fitted by the cap nut 9 and the installation bolt 4 so that a movement to a perpendicular direction to an axial center is carried out, and the core shift absorption means Dm is formed. In addition, the rod parts 12c and 12d and the cylinder part 12b of the to-be-detected body 12 protrude from the cap nut 9, and are attached.

The cover 5 receives the spring 7 and the retainer 8 in the bottomed hole 5a and is attached to the side of the valve body 2, and the spool 3 is attached to the spring 7 and the retainer 8. The neutral position is maintained by The stroke detector 11 is inserted into the sleeve 6 and integrated.

The sleeve 6 is inserted into the cover 5 while inserting the object 12 to be detected into the first hole 6b. At this time, even if the shaft centers of the stroke detector 11 and the spool 3 are shifted, by inserting the 1st hole 6b into the to-be-detected body 12, the to-be-detected body 12 is perpendicular to the shaft 3 with respect to the bush 3. Direction, the core shift is absorbed, and the stroke detector 11 is attached to the cover 5 via the sleeve 6.

Thus, the to-be-detected body 12 moves and absorbs the core shift | offset | difference with the spool 3 by the clearance Cr provided between the cap nuts 9, and the to-be-detected body 12 is sent to the stroke detector 11 It is inserted without twisting. In addition, the cylindrical part 12c of the to-be-detected object 12 is accommodated in the inside of the stroke detector 11 with a very small predetermined clearance gap.

In this state, since the external thread 11b of the case 11a is moved with respect to the detector screw hole 6d of the sleeve 6, the voltage zero point in the neutral position of the stroke detector 11 is adjusted. The stroke detector 11 is fastened to the sleeve 6 by the nut 14 after adjustment, and the assembly ends.

Next, the operation will be described. In FIG. 1, when the spool 3 is operated by an operating lever or the like not shown, the spool 3 strokes against the spring 7 from the neutral position shown in FIG.

With this, the to-be-detected body 12 attached to the spool 3 strokes together. The stroke amount of this to-be-detected body 12 is detected by the stroke detector 11, and is output to the exterior from the stroke detector 11 as an amount of movement of the spool 3.

At this time, since the detected object 12 is guided by the stroke detector 11 to be slidable, the space between the detected object 12 and the stroke detector 11 is kept small and the cylinder 12b is biased. Without this, the detection accuracy can be improved by being arranged near the axis.

Moreover, even if the stroke movement amount is large, since the detected object 12 is guided by the stroke detector 11, the core shift becomes small, and there is no interference between the detected object 12 and the stroke detector 11, Durability and reliability can be improved.

The first valve stroke sensor 1A of the second embodiment will be described with reference to FIG. 2 is a side cross-sectional view showing the first valve stroke sensor 1A. In addition, below, the same code | symbol is attached | subjected to the same component as a prior art example and a 1st Example, and description is abbreviate | omitted.

2, the core shift absorbing means Dm of the first valve stroke sensor 1A is composed of a first mounting bolt 21, an H-shaped joint 22, and a first to-be-detected body 12A.

The first mounting bolt 21 has one end screw 21a screwed into the screw hole 3a at one end and a rod joint 21b at the other end. As for the rod joint part 21b, the spherical shape 21c connected to the H-shaped joint 22 is provided in the front-end | tip. The first mounting bolt 21 is screwed into the screw hole 3a drilled on the shaft center of the spool 3.

The H-shaped joint 22 is formed in an H-shape, and both connecting holes 22a fitted in the spherical shape 21c of the first mounting bolt 21 are drilled. The H-shaped joint 22 is connected to the first mounting bolt 21 on one side and the connection hole 22a on the other side of the first to-be-detected body 12A.

12 A of 1st to-be-detected bodies are connected to the spherical shape 12e and the spherical shape 12e in the one end part on the side of the spool 3, and the rod part 12c, 12d with the step | step is further in the other end side. The cylinder part 12b is formed. The spherical shape 12e of the first to-be-detected body 12A is fitted into the connection hole 22a of the H-shaped joint 22, and the first to-be-detected body 12A is connected to the H-shaped joint 22. As shown in FIG. .

In the above description, the H-shaped joint 22 is formed of an elastic body and may be connected to the spherical shape 21c of the first mounting bolt 21 and the spherical shape 12e of the first to-be-detected body 12A. The H-shaped joint 22 is inserted into the first hole 6b of the sleeve 6. As a result, the H-shaped joint 22 is connected to the first to-be-detected body 12A and the first mounting bolt 21, and the H-shaped joint 22 is held by the first hole 6b of the sleeve 6. Therefore, the connection is easily performed.

Since the assembly and operation in the above configuration are the same as those in the first embodiment, the description is omitted.

The second valve stroke sensor 1B of the third embodiment will be described with reference to FIG. 3 is a side sectional view showing the second valve stroke sensor 1B. In addition, below, the same code | symbol is attached | subjected to the same component as a conventional example and a 1st Example, and description is abbreviate | omitted.

In FIG. 3, the core shift absorbing means Dm of the 2nd valve stroke sensor 1B is comprised by the 1st to-be-detected body 12B, the 1st spring 25, and the spring accommodating part 26. In FIG.

The second to-be-detected body 12B has a sphere 12f at one end of the spool 3 side and a spring receiving sheet portion 12g that is in contact with the sphere 12f, and a rod portion having a step at the center portion. (12h, 12j), and the other end side, the cylindrical portion 12b is formed. The sphere 12f of the second to-be-detected body 12B is coated and attached by the spring receiving sheet portion 12g.

The spring accommodating seat portion 12g supports the spring accommodating portion 26 pressed by the first spring 25. The spring receiving seat portion 12g receives the elastic supporting force of the first spring 25 and presses the second detected object 12B to the spool 3. As for the 1st hole 6b which supports the large diameter rod part 12h, the coaxiality with the 3rd hole 6e of the sleeve 6 is acquired. The large diameter rod portion 12h is supported by the sleeve 6 so as to be slidable in the first hole 6b. Since the large-diameter rod portion 12h is hermetically inserted with respect to the first tongue portion 6b of the sleeve 6 at a predetermined length and slides without being inclined, the cylindrical portion 12b of the object to be detected 12 Can be accommodated in a very small predetermined gap inside the stroke detector 11. The other small diameter rod portion 12j connects the large diameter rod portion 12h and the cylindrical portion 12b.

One end of the first spring 25 is supported by the sleeve 6 and the other end of the first spring 25 is supported by the second to-be-detected body 12B. The 1st spring 25 presses the 2nd to-be-detected body 12B to the end surface of the bush 3 via the spring accommodating part 26, and the 2nd blood with the stroke of the spool 3 is carried out. The detector 12B is stroked together.

Although the second to-be-detected body 12B is separated from the spool 3, the sphere 12f is constantly contacted by the spool 3 by the pressing of the first spring 25, and the integration is achieved. have. As a result, the second to-be-detected body 12B is immediately pressed by the sphere 12f when moving along with the stroke of the spool 3, and the second to-be-detected body 12B is the first hole of the sleeve 6 ( Guided by 6b), it slides. For this reason, even if the clearance gap with the stroke detection part 10 is made small, the 2nd to-be-detected body 12B will not interfere, and detection accuracy can also be improved.

In one example of the assembly in the above configuration, the cover 5 receives the spring 7 and the retainer 8 in the bottomed hole 5a and is attached to the side surface of the valve body 2, and the spool 3 ) Is in neutral position. Next, the first spring 25 and the spring receiving portion 26 are attached to the second to-be-detected body 12B, and the second to-be-detected body 12B is attached to the sleeve 6 and the stroke detector 11. Is integrated into the unit. The sleeve 6 and the stroke detector 11 are inserted and screwed in from the detector screw holes 6d of the cover 5. As a result, the second valve stroke sensor 1B can be simply assembled.

Since the operation is the same as in the first embodiment, the description is omitted.

In the above embodiment, the sleeve 6 and the case 11a of the stroke detector 11 are separately formed, but may be formed integrally. As a result, the detected object is supported by the stroke detection unit 10. At this time, the stroke detector 11 may be moved relative to the cover 5 in the left and right directions of the illustration to adjust the zero point of the electrical signal at the neutral position.

As described above, according to the valve stroke sensor of the present invention, the core deviation of the spool and the stroke detection unit is absorbed, so that processing and assembly are easy, and the detection accuracy is high.

Claims (5)

In the valve stroke sensor, An object to be attached to the spool end of the valve and to stroke with the spool; A stroke detection unit arranged to cover the outside of the object to be detected and outputting a signal according to the stroke amount of the object to be detected; And A valve stroke sensor comprising a core shift absorbing means for absorbing a core shift. The valve stroke sensor according to claim 1, wherein a core shift absorbing means is provided between the spool and the stroke detection unit. The valve stroke sensor according to claim 1 or 2, wherein support means for supporting the detected object concentrically is provided in the stroke detection unit. 4. The core displacement absorbing means according to any one of claims 1 to 3, wherein the core displacement absorbing means has a thread portion formed at one end of the spool, a parallel portion of a to-be-detected body provided on the spool side, and a gap allowing the core displacement. A valve stroke sensor comprising a cap nut that covers a parallel portion of a detector and is screwed into a threaded portion of a spool. The valve stroke sensor according to any one of claims 1 to 4, wherein the zero point is adjustable by moving in the axial direction.