JPH01275969A - Flow control valve - Google Patents

Abstract

PURPOSE:To secure such a valve that is excellent in responsiveness and makes a flow rate accurately controllable by forming a notch groove and a seat in a main spool, and energizing this main spool with flow force and spring load acting on the main spool. CONSTITUTION:A main spool 13 is inserted into a valve body 10 with a flow controlling port 11 and a low pressure port 12. This main spool 13 has both first and second large diametral part 14, 15 and a small diametral part 16, and a notch groove 23 is formed in the first large diametral part 14, while a cone seat 17 is installed as well. The main spool 13 is energized to the right by a spring 18 and the cone seat 17 is pressed to a seat 19, while the second large diametral part 15 comes into contact with a movable lever 20a of an electric actuator 20. If this electric actuator 20 is energized with current, the main spool is moved to the left, whereby flow proportioned to a thrust of the actuator 20 flows from an interval between6 the seat 19 and the notch groove 23.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a flow control valve used in a hydraulic system of construction machinery, etc.

[Conventional technology]

As shown in FIG. 5, the main poppet 3 connects the flow rate control port 1 and the drain port 2.
is set to the blocking position by a spring 4, and a drain hole 5 is formed to open the port 1 to the drain port 2, and this drain hole 5 is freely opened and closed by a stem 7 moved by a pilot piston 6, so that the inside of the pilot pressure chamber 8 can be opened and closed. The pilot piston 6 is moved by the pilot pressure to open the drain hole 5 with the stem 7, thereby generating a flow from the port 1 to the drain port 2, and the high pressure oil acting on the shoulder 3a of the main poppet 3 Pressure oil flows out from port 1 to drain port 2 by pushing 3 against spring 4, and drains the pressure oil from port 1 to drain port 2.
Flow control valves are known that control the flow rate of .

[Problem to be solved by the invention]

With such a flow control valve, the pilot piston 6 is displaced by the pilot pressure, which displaces the main poppet 3 to control the flow rate, so there is a time difference between when the pilot pressure flows in and the flow rate changes. Responsiveness becomes poor.

The system requires a pilot pressure supply mechanism because pilot pressure is supplied to the back pressure chamber 7a of the stem 7 to move the stem 7, thereby controlling the pressure in the spring chamber of the main poppet 3 and controlling the flow rate. In addition, not only the stroke of the stem 7 changes due to an error in the supply of pilot pressure, but also leakage from the sliding portion 9 of the stem 7 to the pilot pressure chamber 8 side tends to occur, making it impossible to accurately control the flow rate.

Therefore, an object of the present invention is to provide a flow control valve that can solve the above-mentioned problems.

[Means and effects for solving the problem] A flow rate control port and a low pressure port are connected to each other by a seat formed in the main spool and a notch groove, and the main spool is placed at a position that blocks the port and the low pressure port. A spring that presses the main spool and an electric actuator that applies a force that pushes the main spool to a position where the port and the low pressure port are communicated through the notched groove are provided. At the same time, the flow force caused by the pressure oil flowing in the notched groove and the direction of movement of the main spool are the same, and the force that pushes the main spool can be precisely and minutely controlled, making it possible to control the flow rate with high precision. It is.

〔Example〕

A main spool 13 that connects the flow rate control port 11 and the low pressure port 12 is slidably inserted into the valve body 10 along the valve hole 10a. It has a diameter section 14.15 and a small diameter section 16, and has a first large diameter section 1.
4 is provided with a seat, for example a cone seat 17, and is pushed rightward by a spring 18 so that the cone seat 17 is pressed against the seat seat 19, and the valve body 1 is attached to the second small diameter portion 15.
The movable rod 20a of the electric actuator 20 attached to the electric actuator 20 is in contact with the movable rod 20a, and the main spool 13 is pushed to the left against the spring 18 by the thrust of the movable rod 20a proportional to the current supplied to the electric actuator 20. As a result, the cone seat 17 is separated from the seat seat 19, and pressure oil flows from the port 11 to the low pressure port 12 through the notched groove 23 formed in the first large diameter portion 14.

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 and communicates with the tank 25.

As shown in FIG. 2, the seat may be a spherical sheet 26 and the seat seat 19 may be spherical, or a combination of both may be used.

Further, as shown in FIG. 3, a small diameter protrusion 27 is integrally formed on the first large diameter part 14 of the main spool 13.
At the same time, the cone sheet 17 is fitted to the retainer 28.
The cone seat 17 may be attached by tightening with a nut 29 via the nut 29.

In the held or neutral state, the main spool 13 is pushed to the right by the force of the spring 18, and the cone seat portion 17 presses against the seat seat 19, blocking the port 11 and the low pressure port 12, and reducing the amount of internal leakage. In other words, the leakage from the port 11 to the low pressure port 12 is made zero.

At this time, the leakage to the chamber 21 side facing the movable rod 20a is caused by the second
The gap between the large diameter portion 15 and the valve hole 10a is made small, and the fitting dimension p1 is made large to minimize the gap. However, by attaching the seal ring 15a to the second large diameter portion 15, the leakage can be virtually eliminated.

Furthermore, when the value of the current supplied to the electric actuator 2o is increased, the thrust of the movable rod 20a increases, pushing the main spool 13 to the left against the spring 18, and first the cone seat 17 and the seat seat 19 are moved. Then, the notch groove 23 of the first large diameter portion 14 opens to the low pressure port 12, and the port 1
1 pressure oil gradually begins to flow through the notched groove 23, is discharged to the low pressure port 12, and flows out into the tank 25.

As a result, the flow rate of the port 11 becomes a predetermined flow rate determined by the spring force of the spring 18 and the thrust of the movable rod 20a of the electric actuator 2o. That is, the notch groove 23 and the spring force of the spring 18 are set so that the flow from the port 11 to the low pressure port 12 flows in response to the force pushing the main spool 13 to the left. Flow rate can be controlled with high precision.

In addition, the thrust force of the electric actuator 20 is applied to the right end surface of the second large diameter portion 15 of the main spool 13 so that the main spool 13
Therefore, when the supply current of the electric actuator 20 is changed, the thrust force increases immediately and the main spool 1 is pushed to the left.
3 moves to the left, the response is good, and the pushing force can be precisely and minutely controlled, so the flow rate can be controlled with high precision.

In addition, since the flow force and spring load from the flow flowing through the notched groove 23 are used, a flow rate proportional to the solenoid thrust can be flowed regardless of the pressure of the port 11, and the pressure compensation bone flow 2 control valve and,
Flow rate can be controlled with even greater precision.

FIG. 4 shows a second embodiment, in which the first large diameter portion 14 of the main spool 13 and the cone seat 17 are spaced apart from each other in the axial direction.

〔Effect of the invention〕

By pushing the main spool 13, the pressure oil in the port 11 flows out to the low pressure port 12 through the notched groove 23, so by pushing the main spool 13 with the electric actuator 20, the pressure oil in the port 11 immediately flows to the low pressure port 12, so there is a response. In addition to having good performance, it can be used as a pressure compensating bone flow control valve by using the flow force and spring load generated by the pressure oil passing through the notch groove 23, and moreover, the electric actuator 2
Since the force that pushes the main spool can be accurately and minutely controlled by setting 0, the flow rate can be precisely controlled in accordance with the thrust of the electric actuator 20.

Further, since the main spool 13 only blocks the port 11 and the low pressure port 12, internal raffle is less likely to occur.

[Brief explanation of the drawing]

1 to 4 show embodiments of the present invention, and FIG. 1 is a first embodiment of the present invention.
2 and 3 are explanatory diagrams of different embodiments of the sheet, FIG. 4 is a sectional view of the second embodiment, and FIG. 5 is a sectional view of a conventional example. 11 is a port, 12 is a low pressure port, 13 is a main spool,
18 is a spring, 19 is a seat seat, 20 is an electric actuator, and 23 is a notched groove. Applicant Komatsu Manufacturing Co., Ltd. Representative Patent Attorney Masaaki Yonehara

Claims (1)

[Claims] A notch groove 23 and a seat are formed in the main spool 13 that connects the flow rate control port 11 and the low pressure port 12, and the main spool 13 is attached by a spring 18 in the direction in which the seat is pressed against the seat seat 19. Then the main spool 1
3 to separate the seat and the seat seat 19 against the spring force, and an electric actuator 20 for pushing the main port 11 to a position where it opens to the low pressure port 12 through the notch groove 23. valve.