JPS6352244B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a servo valve, and particularly to a servo valve using a hydraulic actuator.

[Prior art] Control valves using spools, whether solenoid valves or hydraulic valves, are difficult to process to achieve so-called zero polymerization. Conventionally, when the spool reaches the neutral position, all ports are blocked and closed. They are often of the so-called forward polymerization overlap valve type.

Of course, in order to improve the accuracy of controllability as a control valve, it is required to use zero polymerization, which is the ideal form, unless there are special circumstances, and a servo valve was proposed as one of the countermeasures.

Figures 1 to 3 show such conventional servo valves, in which 1 is the sleeve, 2 is the spool, 3 is the pressure oil ( _Ps ) port, 4 is the return (R) port, and 5 is the A control port. Port 6 is designated as the B control port, and spool 2
is provided with a land portion 7 corresponding to the hydraulic port 3 and the return port 4. Note that 8 and 9 indicate annular openings of the pressure oil port 3 and the return port 4, respectively.

10 in the figure is a hydraulic actuator, and chambers 12 and 13 are formed on the left and right through a piston 11, and the control port 5 of the servo valve is connected to the chamber 12.
The control ports 6 are connected to the chambers 13, respectively.

Then, the spool 2, which is reciprocatably assembled in the sleeve 1, is moved in the direction of the arrow X (to the right in the figure).
When the _piston 11 is displaced to
At the same time, the oil in the chamber 13 is returned to the tank (not shown) or elsewhere via the control port 6 and the return port 4. Spool 2 is pointing backwards to Y
When displaced in the direction (to the left in the figure), the hydraulic actuator 10 performs a movement opposite to the above.

Therefore, in the case of a servo valve that performs such a movement, in order to make the displacement of the piston 11 accurately proportional to the displacement of the spool 2, on the spool 2 side: the axis a1 in the axial direction of each land portion 7;
And, it is necessary to process so that the distance _b1 between each land portion 7 and the width a2 of the annular opening of the pressure oil port 3 on the sleeve 1 side satisfy a1=a2 and b1=b2.

[Problems to be solved by the invention] However, in the case of conventional servo valves, it is necessary to perform processing such as hollowing out the inner surface of the sleeve 1 with a full-form tool etc. There was a problem in that dimensional control required advanced technology and high-precision processing machines. In other words, cutting the width a2 and distance b2 on the sleeve 1 side, and especially cutting the annular openings 8 and 9, requires machining on the inner surface of the cylinder, making dimensional measurement management extremely difficult and machining costs extremely high. It was hot.

[Means for Solving the Problems] The present invention was made in view of such conventional problems, and includes a sleeve for pressure oil, a return port, and a control port in a sleeve having pressure oil, return, and control ports. In a servo valve in which a spool with a corresponding land portion is reciprocatably combined, the sleeve has a hollow cylindrical shape and is provided with openings for the pressure oil and return port along the axial direction, and The distance between the centers of the openings is P1, and the diameter of each hole is d1.
2 (however, P2=P1), and the outer diameter is d2 (however, d
2=d1), and includes a pin that comes into sliding contact with the inner surface of the sleeve together with each land portion, and the land portion slides into sliding contact with the land portion in the axial direction from the periphery of each pin toward the shaft portion between the land portions. It is an object of the present invention to provide a servo valve characterized by having a channel-shaped recessed passage having a width W (where W≦d1 and d2) that communicates the surface and the side surface.

[Operation of the invention] That is, when a spool obtained by accurately controlling dimensions so as to satisfy even the conditions of dimensions P1=P2 and d1=d2 is assembled with a sleeve, the pressure oil port and return port of the sleeve are The center distance between the holes and the spool pin, the hole diameter of the sleeve's pressure oil port and return port, and the spool pin diameter are the same, so when the spool is not moved, the ports and pins are completely aligned. , resulting in a so-called zero polymerization state.

Then, when the spool is moved, the passage of the spool opens to the openings of the pressure oil port and the return port in accordance with the displacement of the spool.

Therefore, the displacement of the spool appears as a parallel movement of the pin, and the opening areas of the pressure oil port and return port on the sleeve side are approximately proportional to the displacement of the spool, and the output flow rate changes with respect to the displacement of the spool. It is a proportional relationship.

[Example] Hereinafter, an example of the present invention will be described based on the drawings. Note that, in the following, parts common to those in the prior art will be indicated by the same reference numerals, and redundant explanation will be omitted.

4 to 10 show one embodiment of the present invention.

The sleeve 1 has a pressure oil port 3, a return port 4,
Although the control ports 5 and 6 are provided as in the conventional case, the annular openings 8 and 9 are not present, and the pressure oil port 3 and return port 4 are opened as they are on the cylindrical inner surface of the sleeve 1. That is, the sleeve 1 has a pressure oil port 3 and a return port 4 on its cylindrical inner surface, which have a center-to-center distance of P1 in the axial direction and have the same hole diameter of d1.
and is open on the hollow inner surface side.

On the other hand, the spool 2 has pins 20, 2 on the land portion 7.
1, 22 and passages 23, 24, 25.
The land portions 7 are formed on the spool 2 in positions and numbers corresponding to the pressure oil ports 3 and the return ports 4, and the land portions 7 are provided with a center-to-center distance of P2 in the axial direction and an outer diameter of the same size. pin 2 as d2
0, 21, 22 are attached, and land portions 7, 7 are further attached from the periphery of each pin 20, 21, 22.
Passages 23, 24, 2 toward the shaft portion 28 between
5 is provided. Each of the passages 23, 24, and 25 is recessed in the shape of a groove so that the sliding surface 26 and the side surface 27 communicate with each other in the axial direction of the land portion.

And the above dimensional conditions are P1=P2, d1=d
It is listed as 2. Further, the width W of the passages 23, 24, and 25 is set as W≦d1 (of course, it is also equal to d2).

Formation of pressure oil port 3 and return port 4 to sleeve 1, and pins 20, 21, 2 to spool 2
2 and the formation of passages 23, 24, 25 are carried out as follows.

First, each land portion 7 of the spool 2, specifically the sliding surface 26 of each land portion 7, is provided with a passage 2 having a width of W.
3, 24, and 25 are recessed in the shape of grooves. These passages 2
The depth of the grooves 3, 24, and 25 is arbitrary as long as it does not reach the spool 2 and the shaft portion 28.
If 3, 24, 25 are formed in the axial direction, the sliding surface 2
6 is in communication with the side surface 27.

Next, a hole 29 having its center on the center line of the passages 23, 24, 25 is bored. At this time, the distance between the centers of the holes 29 is set to P2, and the outer diameter is set to d2. Then pins 20, 21, 22 to the hole 29.
are press-fitted, and the portions protruding from the sliding surface 26 are cut or polished to align the top surfaces of each pin 20, 21, 22 with the sliding surface 26 of each land portion 7. Then, with this much work, pins 20 and 2 of the above conditions
1 and 22 and the passages 23, 24, and 25 are recessed.

Further, in the case of the sleeve 1, the holes for the pressure oil port 3 and the return port 4, which have the same hole diameter d1, are formed on the cylindrical surface in a direction perpendicular to the axial direction at positions that satisfy the distance P1 between the centers of the holes. All you have to do is form it and face it.

In other words, machining that satisfies the conditions of dimensions P1=P2, d1=d2 can be performed on the sleeve 1 but not on the spool 2.
Even in this case, there is no need for troublesome machining such as hollowing out the center using a full-form tool using a special machine, and the machining, cutting, and drilling of bar materials can be carried out accurately and accurately using general lathe machining, etc. Easy to do.

With the spool 2 and sleeve 1 thus obtained, as shown in FIG. 10, displacement of the spool 2 appears as parallel movement of the pins 20, 21, and 22. Therefore, the opening area of the pressure oil port 3 and return port 4 on the sleeve 1 side is
The opening area of passages 23, 24, 25 is due to the movement of ports 1 and 22, and the displacement of spool 2 and each port 3,
4 is approximately proportional to the opening area of the spool 2, and the output flow rate is proportional to the displacement of the spool 2. It goes without saying that a key or other means may be appropriately incorporated to prevent the spool 2 from rotating.

FIG. 11 is a diagram showing a second embodiment of the invention. The first embodiment shown in FIGS. 4 to 10 is a so-called four-way valve, and the second embodiment shows a case where the present invention is applied to a three-way valve. Since one return port 4 is used as the control port C, the number of ports is three, and the spool 2
The second embodiment is substantially the same as the first embodiment except that one land portion 7 on the side is omitted, and common parts in the drawings are designated by the same reference numerals and redundant explanation will be omitted.

[Effects of the Invention] As explained above, according to the present invention, the center-to-center distance P1 and diameter d1 of each opening for the pressure oil port and return port provided in the sleeve, and the center-to-center distance of the pin provided in the spool. P2, the diameter d2 and the width W of the passage, the center distance is P1 during processing.
= P2, the diameter is d1 = d2, and the width W = d
This has the effect that a so-called zero-polymerization servo valve, which conventionally required troublesome processing, can be easily manufactured by simply processing it so that the dimensional relationship is 1 and d2.

In addition, since the openings of the pressure oil ports and return ports correspond to the opening area of the passages due to the movement of the pins relative to each port, it is easy to make the openings of the ports almost proportional to the displacement of the spool, making it possible to perform highly accurate control. There is also an effect.

[Brief explanation of the drawing]

Fig. 1 is a sectional view showing a conventional example of a servo valve, Fig. 2 is a sectional view of a conventional sleeve, Fig. 3 is a side view of a conventional spool, and Fig. 4 is a first embodiment of the present invention. A sectional view of a servo valve showing an example, FIG. 5 is a sectional view of the main part of the spool, FIG. 6 is a plan view of the spool, FIG. 7 is a perspective view of the spool, and FIG. 8 is a sectional view of the spool. Figure 9 is an enlarged sectional view taken along the arrow line in Figure 4, Figure 10 is the relationship between the displacement of the spool and the opening area of the port. FIG. 11 is a sectional view corresponding to FIG. 4 showing the second embodiment. 1: Sleeve, 2: Spool, 3: Pressure oil port, 4: Return port, 5, 6: Control port, 7:
Land part, 20, 21, 22: Pin, 23, 2
4, 25: Passage, 26: Sliding surface of land portion, 2
7: Side surface of land part, 29: Hole, P1: Distance between centers of openings for pressure oil and both return ports, P2: Distance between centers of pins, d1: Hole diameter of openings for pressure oil and both return ports , d2: outer diameter of the pin, W: width of the passage.

Claims (1)

[Scope of Claims] 1. A servo valve in which a spool with a land portion corresponding to the pressure oil and return ports is reciprocatably combined in a sleeve having pressure oil, return and control ports, has a hollow cylindrical shape, and is provided with openings along the axial direction for the pressure oil and the return port, the distance between the centers of these openings is P1, and the diameter of each hole is d1, and the spool is connected to the inner surface of the sleeve. A plurality of lands are provided in sliding contact with each other, and each land has a center-to-center distance of P2 (however, P2=P1) and an outer diameter of d2 (however, P2=d1) in the axial direction. The land portion has a width W (provided that W≦d1 and A servo valve characterized in that the passage (d2) is provided in a recessed groove shape.