JP2001153240A - Direction selection valve - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a direction selection valve capable of improving assembling efficiency by obtaining a desired flow gain without a sleeve. SOLUTION: The output flow of a working fluid flowing out through communicating holes 26, 27 of a spool 20 is determined not depending on the diameter of a cylindrical part 22 which is the diameter of the spool 20, but depending on the opening diameter of the communicating holes 26, 27 and the position of arrangement of the communicating holes 26, 27, whereby a desired flow gain can be obtained by varying the opening diameter of the communicating holes 26, 27 or the position of arrangement of the communicating holes.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a directional control valve for switching a destination of a working fluid supplied from a working fluid supply source.

[0002]

2. Description of the Related Art As a conventional directional control valve, for example, there is one shown in FIG. That is, the main body 1 of the switching valve
The spool 2 moves in the axial direction (the direction a and the direction b) to switch the flow. Spool 2 in a direction
Is moved, the supply port P communicates with the control port A, the control port B communicates with the return port T, and the flow of the working fluid is generated. When the spool is moved in the direction b, the supply port P and the control port B communicate with each other, and the control port A and the return port T communicate with each other, so that the working fluid can flow.

The spool 2 is operated by a manual operation, a mechanical operation by a machine such as a cam roller, a pilot pressure operation by a pilot pressure, an electromagnetic operation by an electromagnetic force, and a pressure of a pilot portion operated by an electromagnetic force. There is an electromagnetic pilot type that operates the main spool.

Such a directional control valve is used in many industrial machines that control the position and speed of the actuator by controlling the flow rate by holding the position of the spool 2 at an arbitrary value.

When the spool 2 is displaced and the working fluid passes through the flow path, the working fluid is restricted and the flow velocity increases,
The pressure is locally reduced by Bernoulli's theorem. This is described in 1986 Edition Practical Hydraulic Pocket Book published by Japan Hydraulic Manufacturers Association, pages P22 and P23.

FIG. 5 is a partially enlarged sectional view of FIG. FIG.
In the following, the force acting on the spool 2 will be described. When the diameter D of the spool 2 and the opening amount xν of the valve are F1, the force that constantly acts in the axial direction is represented by the following equation. F1∝−Fcosθ ≒ −2CdπDxν (P1−P2) cosθ (1) where Cd is a flow coefficient, θ is a jet ejection angle, and P1 and P2.
Is the pressure upstream and downstream of the valve. F1 is called a steady fluid force and acts in a direction to close the valve.

In the equation (1), the term CdπDxν (P1−P2) is proportional to the output flow rate Q2, and can be rewritten as follows. F1∝Q2cos θ (2) This means that the steady-state fluid force F1 is proportional to the product of the output flow rate Q2 and the cosine cos θ of the ejection angle θ. Therefore, the operating force Ft of the spool 2 also needs to be increased in proportion to the flow rate. For this reason, it is necessary to provide a pilot valve in the directional switching valve having a large output flow rate Q2 to provide a two-stage type in which the spool 2 is operated by the pilot pressure.

Further, in such a directional control valve, as described in FIG. 5, the output flow rate Q2 passing through the opening of the valve is:
The output flow rate Q2 is proportional to the opening area of the valve and the opening area of the valve is proportional to the diameter D of the spool 2 and the spool displacement (valve opening xv). , The flow rate gain is also uniquely determined. On the other hand, in a servo valve often used in closed loop control, the flow rate gain is related to the loop gain.

Therefore, in order to obtain various desired flow gains, a sleeve 3 is provided between the valve body 1 and the spool 2 as shown in FIG. Is formed, and the flow rate gain is changed by changing the diameter of the hole 4 of the sleeve 3 or the width of the groove.

[0010]

However, in such a conventional directional control valve, the operating force Ft increases in the case of the one shown in FIG. 4 because the steady-state fluid force F1 increases as the output flow rate Q2 increases. However, it is difficult to set the valve to a predetermined opening amount or to maintain the predetermined opening amount, the operability is reduced, and in order to enhance the operability, for example, when a pilot valve is provided, the size becomes large, and the cost increases. However, there is a problem that the bulk increases.

In order to change the flow rate gain without depending on the diameter D of the spool 2, it is necessary to provide a sleeve 3. The sleeve 3 is pressed into the valve body 1 or an O-ring groove is provided in the sleeve 3. After assembling so as to eliminate leakage between the ports, it is necessary to fit the spool 2 to the sleeve 3, and there is a problem that the assembling is not easy and the assembling property is poor.

The present invention has been made in view of such a conventional problem, and a direction in which a desired flow rate gain can be obtained without providing a sleeve and the assemblability can be improved. It is an object of the present invention to provide a directional control valve that can provide a directional control valve, prevent an increase in size and cost, and improve operability.

[0013]

The gist of the present invention to achieve the above object lies in the following inventions. [1] In a directional switching valve configured to switch a destination of a working fluid supplied from a working fluid supply source, a plurality of ports (P, A, T) respectively connected to the pressure supply source and the destination are opened. A valve body (10), and a spool (20) that can be communicated between the ports (P, A, T) and can be shut off by moving within the valve body (10). 20) has a cylindrical portion (22) forming the outer shape of the spool (20), and a valve chamber (25) formed inside the spool (20);
The cylindrical portion (22) has a communication hole (26, 27) that can communicate the port (P, A, T) with the valve chamber (25).
A directional control valve, comprising:

[2] In a directional switching valve configured to switch a destination of a working fluid supplied from a working fluid supply source, a plurality of ports (P, A, T) respectively connected to the pressure supply source and the destination. And a spool (20) that can be communicated between the ports (P, A, T) and shut off by moving within the valve body (10), The spool (20)
Is a tubular portion (22) forming an outer shape of the spool (20).
And a valve chamber (2) formed inside the spool (20).
5), and the tubular portion (22) has communication holes (26, 27) capable of communicating the ports (P, A, T) with the valve chamber (25). Communication holes (26, 27)
Are formed in parallel with each other in the direction of the cylinder axis of the cylindrical portion (22), and the communication holes (26, 27) are arranged in a direction orthogonal to the cylinder axis of the cylindrical portion (22). A directional switching valve, wherein the directional switching valve is provided in the directional control valve.

[3] The valve chamber (25) is formed between a shaft portion (23) forming a central axis of the spool (20) and the cylindrical portion (22). The directional control valve according to [1] or [2].

Next, the operation of the invention described in each of the above items will be described. The working fluid flows into the valve chamber (25) of the spool (20), then flows out of the communication holes (26, 27), and flows out of the working fluid from predetermined ports (P, A, T) to a predetermined destination. Sent.

The communication holes (26, 27) of the spool (20)
The output flow rate of the working fluid flowing out of the spool (20)
The opening diameter of the communication holes (26, 27) and the communication holes (26, 2) are not determined by the diameter of the cylindrical portion (22),
It is determined by the position where 7) is arranged. Therefore, the opening diameter of the communication holes (26, 27) and the communication holes (26, 2)
By changing the position where 7) is arranged, the cylindrical portion (2
A desired flow rate gain can be obtained without depending on the diameter (2) of the spool (diameter of the spool).

Accordingly, there is no need to provide a sleeve to obtain a desired flow gain, and the sleeve is connected to the valve body (1).
It is not necessary to assemble the valve body (10) simply by attaching the spool (20) to the valve body (10) without the need to press-fit or provide an O-ring groove in the sleeve to eliminate leakage between ports. I do.

Also, a plurality of communication holes (26, 27) are provided side by side in the cylinder axis direction of the cylindrical portion (22).
27) is drilled in a direction perpendicular to the cylinder axis of the tubular portion (22). When the spool (20) moves in the valve body (10), each insertion hole is The working fluid flows in the order in which the working fluids are arranged in the cylinder axis direction, and eventually the working fluid flows through all of the plurality of communication holes (26, 27).

At this time, if the working fluid starts flowing through the first communication holes (26, 27) and the ejection angle at which the working fluid flows out is not perpendicular to the cylinder shaft, the steady fluid force is applied to the spool (20). Works. However, the first communication holes (26, 27)
The output flow rate of the working fluid flowing through the plurality of insertion holes is smaller than the output flow rate of the working fluid flowing through all of the plurality of insertion holes. Therefore, the steady fluid force when the working fluid flows through the first communication holes (26, 27) is small. It will be.

When the working fluid starts flowing into the next communication hole (26, 27), the ejection angle of the working fluid flowing through the first communication hole (26, 27) becomes perpendicular to the cylinder axis.
The steady fluid force of the working fluid flowing through the first communication holes (26, 27) disappears.

As described above, when the working fluid starts flowing into the next communication hole (26, 27), the previous communication hole (26, 2) starts flowing.
Since the steady fluid force of the working fluid flowing in 7) disappears, the steady fluid force of the working fluid does not increase during the predetermined stroke of the spool (20), and is kept small. Therefore, the spool (20) can be operated with a small operating force, and the spool (2) can be operated.
0) can be easily moved to or maintained at a predetermined position, and operability is improved. Also, in order to improve operability, for example, it is not necessary to provide a pilot valve or the like, and the directional control valve can be downsized.

Further, the valve chamber (25) is provided with a spool (20).
In the one formed between the shaft part (23) and the cylindrical part (22) which form the central axis of the valve body, the diameter is adjusted to the diameter of the accommodation hole for the spool (20) formed in the valve body (10). hand,
The outer diameter of the cylindrical portion (22) of the spool (20) is set. The cylindrical portion (22) of the spool (20) may be formed integrally with the shaft portion (23) of the spool (20), or may be formed separately.

When the cylindrical portion (22) is formed integrally, the number of parts can be reduced and the integrated spool (20) can be assembled directly to the valve body (10). ) Is improved. When the cylindrical part (22) is formed separately, the cylindrical part (2) is formed.
What has been previously fitted to the shaft portion (23) may be assembled to the valve body (10), and the assemblability of the spool (20) is improved.

[0025]

Embodiments of the present invention will be described below with reference to the drawings. 1 and 2 show a directional control valve according to an embodiment of the present invention. 1 is a longitudinal sectional view of the directional control valve, and FIG. 2 is a partially enlarged sectional view of the directional control valve.

As shown in FIG. 1, the directional control valve includes a main valve (3) of a proportional valve or a servo valve having a supply port P, a control port A, and a return port T opened in the valve body 10.
). The supply port P is connected to an outlet port of a working fluid supply source (not shown), the control port A is connected to a control target (not shown), and the return port T is a tank port (not shown) of the working fluid supply source. ). In such a directional control valve, a spool position is held in proportion to an input voltage or an input current, and the flow rate is controlled by an opening area determined by the spool position.

A spool 20 is mounted on the valve body 10. The spool 20 forms the outer shape of the spool 20,
It comprises a cylindrical portion 22 having a cylindrical shape, and a shaft portion 23 forming the central axis of the spool 20 (the cylindrical axis of the cylindrical portion 22). The shaft part 23 is press-fitted into the cylindrical part 22.

The shaft portion 23 includes a large-diameter head portion 231, a large-diameter intermediate portion 232, and a small-diameter shaft portion 233.
The flange 234 of the large-diameter head 231 is stopped by the retaining ring 24 in a state where the flange 234 is in contact with the peripheral portion of the press-in port 222 of the tubular portion 22. The retaining ring 24 is resiliently fitted in an annular groove 223 formed in a peripheral portion of the pressure inlet 222 of the tubular portion 22.

The shaft portion 233 of the cylindrical portion 22 and the shaft portion 23
The gap between the large-diameter head 231 and the large-diameter intermediate portion 232 is the valve chamber 25. The tubular portion 22 is provided with an inflow port 221 through which the supply port P or the control port A can communicate with the valve chamber 25.

As shown in FIG. 1 and FIG.
Are provided with two communication holes 26 and 27, which are orifices capable of communicating the control port A or the return port T with the valve chamber 25, respectively.

The communication holes 26 and 27 are arranged side by side in the axial direction of the cylindrical portion 22, and each communication hole 26 and 27 is formed in the cylindrical portion 2.
2 are provided in series at substantially equal intervals in the circumferential direction. Generally, the communication holes 26 and 27 are formed in a circular cross section or a rectangular cross section.

Each of the communication holes 26 and 27 is formed in a direction perpendicular to the central axis of the spool 20 (the cylindrical axis of the cylindrical portion 22). Further, in relation to the flow rate gain, the size of each opening of the communication holes 26 and 27 and the position to arrange them are determined so that the opening area is proportional to the stroke of the spool 20. Further, a communication hole communicating with the return port T is formed in the same manner as the communication holes 26 and 27.

Next, the assembly of the directional control valve will be described. When the shaft portion 23 is pressed into the cylindrical portion 22, the flange 2 of the large-diameter head 231 of the shaft portion 23 is eventually formed.
34 comes into contact with the peripheral edge of the press-in port of the cylindrical portion 22, and press-fitting of the shaft portion 23 is completed. Next, the retaining ring 24 is attached to the cylindrical portion 2.
2 is resiliently fitted in the annular groove 223 of the shaft portion 23.
Is stopped.

Thus, the cylindrical portion 22 and the shaft portion 23
Can be handled integrally, and handling becomes easy. The cylindrical portion 22 and the shaft portion 2 thus integrated.
3 is assembled to the valve body 10, the assembly of the direction switching valve is completed, the assembly of the valve body 10 and the spool 20 can be simplified, and the assemblability of the direction switching valve is improved.

Next, the steady fluid force of the working fluid will be described. When the spool 20 is slightly displaced in the direction a, the working fluid is guided from the supply port P to the valve chamber 25 and flows out through the communication hole 26 to the control port A, and when the communication hole 27 is closed, the communication hole 26 is closed. , In a state of approaching the edge surface 14 of the control port A of the valve body 10. Accordingly, since the opening between the end surface of the communication hole 26 and the edge surface 14 is small, the ejection angle θ of the moving fluid flowing out of the communication hole 26 is small, and the opening amount is small and the ejection angle θ of the working fluid is small. Since the output flow rate Q2 is also small in a small range, the steady fluid force of the working fluid is small.

Next, as shown in FIG. 1, the spool 20 is further displaced in the direction a, and the working fluid is guided from the supply port P to the valve chamber 25 and flows out to the control port A through the communication holes 26 and 27. In this state, the communication hole 26 has already passed through the edge surface 14 of the control port A of the valve body 10. As a result, the ejection angle θ of the working fluid flowing out of the communication hole 26 is obtained.
Is 90 degrees, and no steady-state fluid force is generated from equation (1).

The communication hole 27 is in a state of reaching the edge surface 14 of the control port A of the valve body 10 like the communication hole 26 described above. Thereby, the steady fluid force of the working fluid flowing out of the communication hole 27 becomes small. That is, the steady fluid force of the working fluid flowing out of the communication holes 26 and 27 becomes small as a whole.

Further, the spool 20 is displaced in the direction a,
In a state where the working fluid is guided from the supply port P to the valve chamber 25 and flows out to the control port A through the communication holes 26 and 27, both the communication holes 26 and 27 are the edge surfaces of the control port A of the valve body 10. 14 has already passed. Thereby,
The ejection angles θ of the working fluid flowing out of the communication holes 26 and 27 are both 90 degrees, and no steady fluid force of the working fluid flowing out of the communication holes 26 and 27 is generated.

That is, when the spool 20 is moved to the predetermined stroke position or is maintained at the predetermined stroke position, it is not necessary to control the position of the spool 20 with a large operation force, and the operability is improved.

In the above embodiment, the present invention is applied to the proportional valve and the servo valve. However, the present invention can also be applied to the case where the spool position of the directional control valve is controlled manually or by a mechanical input. Also, the present invention can be applied to an electromagnetic switching valve that is turned on / off by an electromagnetic force.

In the above-described embodiment, the two communication holes 26 and 27 are arranged in the cylindrical portion 22. However, in order to obtain various desired flow gains, the communication holes need to be formed. However, the shape is not limited to a circular cross-sectional shape or a square cross-sectional shape. Further, the number of communication holes is not limited to two, and may be three or more. Further, unless the operability of the direction switching valve is taken into consideration, the communication holes 26 and 27 are not limited to those formed in a direction perpendicular to the cylinder axis of the cylindrical portion 22.

Further, in the above embodiment, the cylindrical portion 22
Although the shaft part 23 and the shaft part 23 are shown separately, the cylindrical part 22 and the shaft part 23 may be integrated as shown in FIG. Thereby, the number of parts can be reduced. Further, in the above-described embodiment, a three-way valve is shown as the direction switching valve. However, the present invention is not limited to this.

[0043]

According to the directional control valve of the present invention, the working fluid flows out from the valve chamber of the spool to each port through the communication hole formed in the cylindrical portion of the spool.
By changing the opening diameter of the communication hole and the arrangement of the communication hole, various desired flow gains can be obtained, and it is not necessary to provide a sleeve having a hole of a predetermined shape in order to obtain a desired flow gain. In this case, the spool may be simply assembled to the valve body, and the assembling property can be improved.

Further, a plurality of communication holes are provided in parallel in the direction of the cylinder axis of the cylindrical portion, and each communication hole is formed in a direction perpendicular to the cylinder axis of the cylindrical portion. When the working fluid starts to flow into the hole, the steady fluid force of the working fluid flowing in the previous communication hole disappears, and the steady fluid force of the working fluid is kept small during the predetermined stroke of the spool, The spool can be operated with a small operating force, and the operability is improved.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of a directional control valve according to an embodiment of the present invention.

FIG. 2 is a partially enlarged cross-sectional view of the directional control valve according to one embodiment of the present invention.

FIG. 3 is a longitudinal sectional view showing a modification of the directional control valve according to one embodiment of the present invention.

FIG. 4 is a longitudinal sectional view of a directional control valve according to a conventional example.

FIG. 5 is a partially enlarged view of FIG. 4;

FIG. 6 is a longitudinal sectional view of a directional control valve according to another conventional example.

[Explanation of symbols]

 A ... Control port P ... Supply port T ... Return port 10 ... Valve body 14 ... Edge surface 20 ... Spool 22 ... Cylindrical part 23 ... Shaft part 24 ... Retaining ring 25 ... Valve chamber 26,27 ... Communication hole 221 ... Inflow port 222 ... Press-in port 223 ... Circular groove 231 ... Large diameter head 232 ... Large diameter middle part 233 ... Shaft part 234 ... Flange

Claims (3)

[Claims] 1. A directional control valve configured to switch a destination of a working fluid supplied from a working fluid supply source, comprising: a valve body having a plurality of ports connected to the pressure supply source and the destination, respectively; A spool capable of communicating with and shutting off between the ports by moving within the valve body; the spool having a tubular portion forming an outer shape of the spool; and a valve formed inside the spool. A direction switching valve, comprising: a chamber; and the cylindrical portion has a communication hole that allows communication between the ports and the valve chamber. 2. A directional switching valve configured to switch a destination of a working fluid supplied from a working fluid supply source, a valve body having a plurality of ports respectively connected to the pressure supply source and the destination, A spool capable of communicating with and shutting off between the ports by moving within the valve body; the spool having a tubular portion forming an outer shape of the spool; and a valve formed inside the spool. And the cylindrical portion has a communication hole capable of communicating each of the ports and the valve chamber. A plurality of the communication holes are arranged in the cylinder axis direction of the cylindrical portion. The direction switching valve, wherein each of the communication holes is formed in a direction orthogonal to a cylinder axis of the cylindrical portion. 3. The directional control valve according to claim 1, wherein the valve chamber is formed between a shaft portion forming a central axis of the spool and the cylindrical portion.