JPH0651504U - Control valve - Google Patents

Abstract

(57) [Summary] [Purpose] To simplify the machining of the body and improve the positional accuracy with respect to the spool. [Structure] The casting holes 11 and 12 formed in the sliding hole 10 of the body 1 pass through the through hole 13, the sliding hole 10, the through hole 14 and the through hole 15, the sliding hole 10 and the through hole 16 at right angles to the axis. To the opening 1 by wire-cut electrical discharge machining
7 and 18 and adjacent lands 31 and 3 of the spool 3 are formed.
2 and 33, 34 between the outer side surfaces 31a, 32a and 33
The distance between a and 34a is made equal to the axial width D of the openings 17 and 18, and the land width W is set to the width of the openings 17 and 1.
8 is equal to or less than the widening length E of 8 minus the stroke S of the spool 3.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a control valve such as a servo valve or a proportional valve, and more particularly to a control valve that can maintain the relationship between a body and a spool with high precision with a simple structure.

[0002]

[Prior art]

 Conventionally, in order to ensure high pressure resistance and durability with this type of control valve, it was necessary to use a high hardness sleeve on the sliding surface of the spool.

FIG. 12 shows a schematic structure of a directional flow control valve usually called a servo valve. A high hardness sleeve 2 is fitted in a sleeve hole 1a of a body 1, and an inner peripheral surface of the sleeve 2 is formed. The spool 3 is slidably loosely inserted into the valve hole 2a. The widths A1 and B1 of the circumferential grooves 2b and 2b 'of the sleeve 2 which are required to have the highest dimensional accuracy are processed with extremely high accuracy by a wire cut electrical discharge machining method or the like, and the interval C1 is also highly accurate. I kept it.

However, since the valve construction using such a sleeve has low productivity and is extremely expensive, the control valve generally used as a proportional valve in a relatively low pressure line is shown in FIG. As described above, the body 1 without the sleeve has been used in which the circumferential grooves 1c and 1c 'formed in the valve sliding hole 1b in which the spool 3 slides by casting are turned beforehand.

[0005]

[Problems to be solved by the device]

 However, in such a conventional control valve body that has been turned, the dimensional accuracy of the widths A2 and B2 of the grooves 1c and 1c 'shown in FIG. 13 and the interval C2 thereof is the same as that of the grooves 2b and 2b shown in FIG. Since the precision of one digit or two digits deteriorates due to the dimensional precision of the widths A1 and B1 of ′ and the interval C1 thereof, the stroke of the spool is increased by almost one digit to cover the degradation of the precision.

For example, with a high-precision body using a high-hardness sleeve, the processing accuracy of the sleeve is 0. When the full stroke of the spool is 0.5 mm at 01 mm, the full stroke of the spool is required to be 5 mm in order to be comparable with the turning body having a machining accuracy of 0.1 mm. Actually, the full stroke of the control valve spool is often 2 to 3 mm, so the machining accuracy during turning was 0.05 mm, and machining was almost impossible.

Therefore, in a control valve having a body formed by turning, a spool is provided with a taper, a notch or the like so that the spool is overlapped or underlapped at its neutral position, and the flow rate gain is positively reduced to improve the processing accuracy. It covered the lowness. With this configuration, there is a problem that delicate control of the hydraulic pressure due to a slight change in the spool cannot be obtained, and the spool has a large stroke, resulting in poor responsiveness.

Therefore, in the hydraulic system using the control valve composed of the sleeveless turned body as shown in FIG. 13, the system accuracy is as high as that of the control valve composed of the body having the highly accurate sleeve. It has been generally accepted that it is one or two orders of magnitude lower than the system accuracy of existing hydraulic systems.

The present invention has been made in view of the above points, and it is an object of the present invention to significantly improve the positional accuracy with respect to the spool while simplifying the processing of the body as much as possible.

[0010]

[Means for Solving the Problems]

 In order to achieve the above object, the present invention provides a control valve for controlling a flow direction and a flow rate by causing a spool to slide in a sliding hole of a body in which a casting groove is formed, so that the body is The casting groove is penetrated in a direction perpendicular to the axis of the sliding hole, and an opening is formed on both sides in the axial direction by wire-cut electric discharge machining, and the spool has a width in the axial direction of the opening. A control valve that has a pair of adjacent lands that have the same distance between the outer surfaces, and the width of each land is less than or equal to the widening length on one side of the above opening minus the stroke of this spool. Is provided.

[0011]

[Action]

 By configuring the control valve according to the present invention as described above, the machining of the casting groove for forming the passage formed in the sliding hole of the body is omitted or the chipping of the casting is prevented. The chamfering level is set to a level that is sufficient for machining, and the wire cutting electrical discharge machining method is used to widen the openings on both sides of the casting groove to obtain machining accuracy. The processing accuracy can be greatly improved.

In the spool inserted into the sliding hole, adjacent lands are positioned at both ends of the opening in a neutral state, and when the spool moves in the axial direction from this state, the flow direction is switched. At this time, the land width of the spool is set to be equal to or less than the widening length of one side of the above opening minus the stroke of the spool, so that even if the spool moves a full stroke in the axial direction, There is no risk that a part of them will go into the casting groove and the pressure distribution in the circumferential direction due to the width of the land will be uneven, and the imbalance in the radial pressing of the spool will not occur, thus stabilizing the spool. It becomes possible to move.

[0013]

【Example】

 An embodiment of the present invention will be specifically described below with reference to the drawings. 1 is a plan view showing an embodiment of the present invention, FIG. 2 is a side sectional view thereof, FIG. 3 is a plan view showing a state of the body before wire-cut electric discharge machining, and FIG. 4 is a side sectional view thereof. 5 is a plan view showing a state after wire-cut electric discharge machining, FIG. 6 is a side sectional view thereof, FIG. 7 is a perspective view showing a wire-cut electric discharge machining state of the body, and FIG. 8 is a side view showing a spool shape. .

As shown in FIGS. 3 and 4, the body 1 before the wire-cut electric discharge machining is provided with a sliding hole 10 and a casting groove 11 formed at a predetermined position in the axial direction of the sliding hole 10. , 12 and through holes 13, 14, 15, 16 for wire cut electric discharge machining. The through holes 13, 15 are provided in the upper surface 1d of the body 1, and the through holes 14, 16 are provided in the mounting surface 1e. The through holes 13 and 14 and the through holes 15 and 16 are located on the same axis, the through holes 13, 15 and 14 and 16 have the same diameter, and the casting grooves 11 and 12 have the same width. ing.

Here, as shown in FIG. 7, the wire electrode 4 is inserted through the through hole 13, the sliding hole 10 and the through hole 14, and the body 1 is moved in the X and Y directions while supplying the working liquid. The casting groove 11 shown in FIGS. 3 and 4 is widened to both sides of the sliding hole 10 in the axial direction, and the rectangular hole-shaped opening 17 having the width D shown in FIGS. 5 and 6 is inserted into the through hole 13 of the sliding hole 10. Side and through hole 14 side. Further, the wire electrode 4 is inserted into the through hole 15, the sliding hole 10 and the through hole 16 to similarly form an opening 18 having a width D by electrical discharge machining.

On the other hand, as shown in FIG. 8, the spool 3 inserted into the sliding hole 10 of the body 1 has the outer surfaces 31 a, 32 a of the lands 31, 32 and 33, 34 and the 33 a, 34 a. And the width W of each land 31, 32, 33, 34 is set to be the same as the width D of the openings 17, 18 and the end face of the cast-out grooves 11, 12 of the body 1 as shown in FIG. W ≦ E−S is set so that the distance between the end faces of the openings 17 and 18, that is, the length obtained by subtracting the stroke S of the spool 3 from the widening length E subjected to electric discharge machining is not more than the length.

Next, the operation of the embodiment having the above-described structure will be described. In FIGS. 1 and 2, the relationship between the lands 31, 32 and the opening 17 is as follows. Since the relationship is the same as that of 18, the following description will be made only on the former, and the description on the latter will be omitted.

In the state shown in FIGS. 1 and 2 in which the spool 3 is in the neutral position, the opening 17 is closed by the lands 31 and 32, and the pressure supply port P, the tank connection port T and the load connection port T are connected. Each port C is blocked. FIG. 9 is an enlarged plan sectional view showing the relationship between the opening 17 and the lands 31 and 32. The casting groove 11 has a shape that widens downward in the figure due to the draft, so that there is no chipping of the casting. It is chamfered by a simple boring process to prevent it, but the draft is slightly different on the left and right, and the lower left part of the figure remains unprocessed.

When the spool 3 moves to the right from this state, the left end side of the opening 17 is opened, and the pressure supply port P communicates with the load connection port C via the opening 17 and the casting groove 11. When the spool 3 goes to the right by the full stroke S, S ≦ EW as described above, so that the right side surface 31b of the land 31 is connected to the load from the left side surface 11a of the casting groove 11 as shown by the solid line in FIG. The pressure distribution in the circumferential direction due to the width W of the land 31 of the spool 3 becomes uniform over the entire circumference while remaining in a position where it does not enter the port C, and imbalance due to uneven pressure force in the radial direction does not occur. No, the spool moves smoothly.

In this case, if the full stroke S ′ of the spool 3 is S ′> EW, the lower portion of the right side surface 31b of the land 31 is the casting groove 11 as shown by the phantom line in FIG. Of the land 31a protrudes into the groove from the lower part of the left end surface 11a, but the upper part of the left end surface 11a does not protrude, so that the pressure distribution in the circumferential direction of the land 31 becomes uneven and the smooth movement of the spool 3 is hindered. .

In addition, in FIG. 7 of the above-described embodiment, the case where the wire-cut electric discharge machining is performed for each body 1 has been described. However, if the electric discharge machining machine is large, as shown in FIG. It is also possible to stack the bodies 1 and process them simultaneously with one wire electrode 4. According to this machining method, it is possible to reduce the machining cost per body even with an expensive electric discharge machining method.

Further, in the above-mentioned embodiment, the case where the casting groove is chamfered by the boring process in the pre-processing step has been described, but the chamfering can be performed by another method, and the chamfering can be performed in the as-casted state. By forming a chamfered surface or the like to prevent the corners from missing, the above-mentioned pre-processing becomes unnecessary.

[0023]

[Effect of device]

 As described above, the control valve according to the present invention has the body in which the casting groove formed in the sliding hole is widened in the axial direction by wire-cut electric discharge machining to form the opening, and the outer surface of the adjacent land. Since the distance between them is equal to the axial width of the opening and the land width is less than or equal to the expanded width on one side of the opening minus the stroke of the spool, it is easy to configure. The machining method can significantly improve the axial dimension accuracy of the opening that communicates with the cast hole of the body, and eliminates the expensive sleeve that was conventionally required for a highly accurate control valve.

Further, there is no fear that the pressure distribution acting on the peripheral side surface of the land becomes uneven while the spool moves the full stroke, and the spool can be moved stably without imbalance in pressing in the radial direction of the spool. become.

[Brief description of drawings]

FIG. 1 is a plan view showing an embodiment of the present invention.

FIG. 2 is a side sectional view of the same.

FIG. 3 is a plan view showing a state of the body before wire-cut electric discharge machining.

FIG. 4 is a side sectional view of the same.

FIG. 5 is a plan view showing a state of the body after wire-cut electric discharge machining.

FIG. 6 is a side sectional view of the same.

FIG. 7 is a perspective view showing a wire-cut electric discharge machining state of the same body.

FIG. 8 is a side view of the spool of the same.

FIG. 9 is a plan sectional view of an essential part showing an enlarged relationship between the body and the spool in the neutral position.

FIG. 10 is a plan sectional view of an essential part showing an enlarged relationship between the body and the spool at the position where the body has moved by a full stroke.

FIG. 11 is a perspective view showing another wire cut electric discharge machining state of the body.

FIG. 12 is a sectional view showing an example of a conventional control valve.

FIG. 13 is a sectional view showing another example of a conventional control valve.

[Explanation of symbols]

1 Body 3 Spool 4 Wire Electrode 10 Sliding Hole 11, 12 Casting Groove 13, 14, 1
5,16 through hole 17,18 opening 31,32,3
3,34 lands

Claims (1)

[Scope of utility model registration request] 1. A spool is slid axially in a sliding hole of a body in which a casting groove is formed, whereby
In the control valve for controlling the flow rate, the body includes an opening portion that penetrates the casting groove in a direction orthogonal to an axis of the sliding hole and is widened to both sides in an axial direction by wire cut electric discharge machining. Comprises a pair of adjacent lands having a distance between the outer surfaces that is equal to the axial width of the opening, each land width subtracting the stroke of the spool from the widening length on one side of the opening. A control valve characterized in that the length is equal to or less than the length.