JP2577225B2 - Flow control valve - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a flow control valve used for a hydraulic device of a construction machine.

[Conventional technology]

As shown in FIG. 6, the port 1 for flow control and the drain port 2 are cut off by the main poppet 3, the main poppet 3 is closed by the spring 4, and the port 1 is opened to the drain port 2. A drain hole 5 is formed, and the drain hole 5 is
The pilot piston 6 is moved by the pilot pressure in the pilot pressure chamber 8 and the drain hole 5 is opened by the stem 7 so that the drain port 2 can be opened from the port 1.
The main poppet 3 is pushed against the spring 4 with high-pressure oil acting on the shoulder 3a of the main poppet 3 so that the pressurized oil flows from the port 1 to the drain port 2 and 2. Description of the Related Art A flow control valve that controls a flow rate is known.

[Means and actions for solving the problems]

With such a flow control valve, the pilot piston 6 is displaced by the pilot pressure, whereby the main poppet 3 is displaced.
Is displaced to control the flow rate, so that there is a time difference between the flow of the pilot pressure and the change of the flow rate, resulting in poor responsiveness.

Since the flow rate is controlled by controlling the pressure of the spring chamber of the main poppet 3 with the stem 7, the flow rate cannot be accurately controlled.

Oil leaks easily from the sliding portion 9 of the stem 7 to the pilot pressure chamber 8 side, and the flow rate cannot be controlled accurately.

Therefore, an object of the present invention is to provide a flow control valve capable of solving the above-mentioned problem of the present invention.

[Means and actions for solving the problem]

A main spool 13 that connects and disconnects the flow control port 11 and the low-pressure port 12 to and from the valve hole 10a of the valve body 10 is shut off when it slides toward the flow control port 11, and slides toward the low-pressure port 12 side. The main spool 13 is provided with a notch groove 23 and a sheet, and the main spool 13 is biased toward the flow control port 11 by a spring 18 so that the seat is valved. The port 11 for flow control and the low-pressure port 12 are blocked by pressing against the seat 19 of the main body 10, and the main spool 13 slides toward the low-pressure port 12 against the spring force to move the seat and the seat 19 together. Remote and main port 11
Is a flow control valve provided with a mechanism for applying a pressing force to a position opening the low-pressure port 12 through the notch groove 23. As a result, the port and the low-pressure port communicate with each other as soon as the force is applied, thereby improving the responsiveness and using the flow fence by the pressurized oil flowing through the cutout groove.

〔Example〕

A main spool 13 for disconnecting the flow control port 11 and the low pressure port 12 is slidably fitted along the valve hole 10a in the valve body 10, and the main spool 13 has a first and a second large diameter. The first large-diameter portion 14 includes a seat, for example, a cone seat 17, and the cone seat 17 is pushed to the right by a spring 18 to move the cone seat 17 to the seat seat 19. The second small diameter portion 15 faces the pilot pressure chamber 20, and the pilot pressure of the pilot source 21 is supplied from the pilot signal generator 22 to the pilot pressure chamber 20, and the main spool 13 is moved by the pilot pressure. The cone seat 17 is pushed to the left against the spring 18 so that the cone seat 17 separates from the seat 19, and the first large diameter portion
Pressure oil flows from the cutout groove 23 formed in the port 14 to the low-pressure port 12 from the port 11.

The spring 18 is supported by a spring receiver 24 attached to the valve body 10, and the low-pressure port 12 is formed in the spring receiver 24 to form a tank.
Communicates with 25.

As shown in FIG. 2, the seat may be a spherical seat 26 and the seat 19 may be spherical. Further, a cone sheet and a spherical sheet may be combined.

In addition, as shown in FIG.
The small-diameter projecting portion 27 may be integrally formed with the small-diameter projecting portion 27, the cone sheet 17 may be fitted to the small-diameter projecting portion 27, and the cone sheet 17 may be attached by tightening the nut 29 via the retainer 28.

In the holding or neutral state, the main spool 13 is pushed rightward by the force of the spring 18 and the cone seat portion 17 is seated.
The port 11 and the low-pressure port 12 are closed by crimping to 19, and the amount of internal leakage, that is, oil leakage from the port 11 to the low-pressure port 12 is made zero.

At this time, leakage oil to the pilot pressure chamber 20 side is reduced as much as possible by reducing the gap between the second large diameter portion 15 and the valve hole 10a, and to increase the fitting dimension l _1. However. By attaching the seal ring 15a to the second large diameter portion 15, oil leakage can be made virtually zero.

When the pilot pressure is supplied from the pilot source 21 to the pilot pressure chamber 20 by switching the pilot signal generating device 22, for example, the pilot valve, the pilot pressure acts on the end face of the second large-diameter portion 15 to push the main spool 13 against the spring 18. To the left, the cone seat 17 and the seat 19 are separated from each other.
The notch groove 23 of the large diameter portion 14 opens to the low pressure port 12, and the pressure oil of the port 11 gradually starts flowing through the notch groove 23,
And discharged into the tank 25.

Thus, the flow rate of the port 11 becomes a predetermined flow rate determined by the spring force of the spring 18 and the pilot pressure in the pilot pressure chamber 20. That is, since the flow rate from the port 11 to the low-pressure port 12 is set so that the flow rate thereof flows according to the force pressing the main spool 13 to the left, the spring force of the notch groove 23 and the spring 18 is set. The flowing flow rate can be controlled accurately.

Further, the pilot pressure is applied to the right end face of the second large-diameter portion 15 of the main spool 13 to push the main spool 13 to the left, so that the pressure receiving area is large. Responsiveness is good because it moves to the side.

In addition, the flow rate proportional to the pilot pressure can be flowed regardless of the pressure of the port 11 by using the flow force and the spring load due to the flow of the oil flowing through the notch groove 23, so that a flow control valve with pressure compensation can be provided. It is possible to control the flow rate with higher accuracy.

FIG. 4 shows a second embodiment in which the pilot pressure is
The pressure is increased at 30, and the main spool 13 is pressed against the spring 18.

FIG. 5 shows a third embodiment, in which the first large-diameter portion 14 of the main spool 13 and the cone sheet 17 are spaced apart in the axial direction.

In addition, an electromagnetic proportional pressure control valve, a proportional pressure control valve, or the like may be used as the aforementioned pilot signal generator 22,
The main spool 13 may be directly pushed by a proportional solenoid, or the main spool 13 may be pushed directly by an operation lever via a spring. That is, a mechanism for applying a force for pressing the main spool 13 against the spring force may be provided.

〔The invention's effect〕

Pressing the main spool 13 causes the pressure oil in the flow control port 11 to flow out to the low-pressure port 12 through the notch groove 23.By pressing the main spool 13, the pressure oil in the flow control port 11 immediately flows into the low-pressure port 12. Responsiveness is good because it flows.

Further, since only the flow control port 11 and the low pressure port 12 are shut off by the main spool 13, internal oil leakage hardly occurs.

Also, the direction in which the pressure oil of the flow control port 11 flows through the notch groove 23 to the low pressure port 12 is the same as the direction in which the main spool 13 slides to the position where the flow control port 11 communicates with the low pressure port 12. Therefore, a flow control valve with pressure compensation can be provided by using a flow force and a spring load generated by the pressure oil passing through the notch groove 23.
It is possible to precisely control the flow rate in proportion to the applied force regardless of the pressure of 11.

[Brief description of the drawings]

1 to 5 show an embodiment of the present invention, and FIG.
2 and 3 are explanatory views of different embodiments of the seat, FIGS. 4 and 5 are cross-sectional views of the second and third embodiments, and FIG. 6 is a cross-section of a conventional example. FIG. 11 is a port, 12 is a low pressure port, 13 is a main spool, 18 is a spring, 19 is a seat, and 23 is a cutout groove.

Claims (1)

(57) [Claims] A main spool (13) for communicating / blocking a flow control port (11) and a low pressure port (12) in a valve hole (10a) of a valve body (10).
The main spool 13 is provided with a notch groove 23 and a sheet so as to shut off when sliding toward the flow control port 11 side and to slide when communicating with the low pressure port 12 side. By urging 13 toward the flow control port 11 side with a spring 18, the seat is pressed against the seat 19 of the valve body 10 to shut off the flow control port 11 and the low pressure port 12. A mechanism is provided to slide against the low pressure port 12 side against the spring force to separate the seat and the seat 19, and to apply a force to push the main port 11 to a position where the main port 11 is opened to the low pressure port 12 through the cutout groove 23. A flow control valve characterized in that: