JPS63318374A - Pressure control valve - Google Patents

Abstract

PURPOSE:To obtain a simple structure by installing a pilot poppet which allows the communication between a high pressure chamber and a pilot pressure chamber by the operation of the high pressure oil in the high pressure chamber and allowing the pilot pressure chamber to communicate to a low pressure chamber through an orifice. CONSTITUTION:A main spool 23 for allowing the communication and disconnection between a high pressure chamber 21 and a low pressure chamber 22 is fitted into a valve body 20, and a pilot pressure chamber 25 communicates to the low pressure chamber 22 through an oil hole 28 and an orifice 29. When the pressure in the high pressure chamber 21 becomes the pressure determined by the pressure receiving area of a pilot poppet 32 and the springy force of a spring 33, the pilot poppet 32 is pushed downward, and the pressurized oil flow into the pilot pressure chamber 25 fro the oil hole 28, and the main spool 23 is pushed leftward by the pressure generated on passing through the orifice 29. Therefore, the simple structure is obtained, and the thrust force of the main spool can be increased.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a pressure control valve that prevents damage to hydraulic equipment or hydraulic equipment due to abnormal pressure in a hydraulic circuit.

[Conventional technology]

As shown in FIG. 7, a main poppet 4 and a pilot poppet 5 are provided in the valve body 1 to disconnect the high pressure side 2 and the low pressure side 3, and the pilot poppet 5 resists the spring 6 by the pressure oil on the high pressure side 2. When the main poppet 4 is opened, oil flows from the high pressure side 2 to the low pressure side 3 through the orifice 7 of the main poppet 4, and a pressure difference is generated before and after the main poppet 4, and the main pot 4 opens against the spring 8, and the oil flows from the high pressure side 2 to the low pressure side 3. A pressure control valve is known that communicates with the low pressure side 3 and allows high pressure oil to flow out to the low pressure side.

[Problem that the invention seeks to solve]

In such a pressure control valve, the shaft portion 5a of the pilot poppet 5 faces the high-pressure side 2, and the pilot poppet 5 moves against the spring 6 using its pressure oil to separate the seat portion 5b from the seat seat 9 and release the spring of the main poppet 4. The structure is such that the chamber 4a is communicated with the low pressure side 3 through the oil hole 10, and the structure of the pilot poppet 5 itself becomes complicated, resulting in a complicated structure of the entire pressure control valve.

Further, high pressure oil acts on the shoulder portion 4a of the main poppet 4, and the area on which the high pressure oil acts becomes smaller than the cross-sectional area of the main poppet 4, increasing hysteresis.

Further, since the main poppet 4 is of a cone sheet type, the passage area changes greatly, the hydraulic pulsation is large, and the stability during operation is poor.

Further, since the shaft portion 5a of the pilot poppet 5 faces the high-pressure side 2, it is difficult to integrate the structure and the size increases.

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

[Means and actions for solving the problem] The main spool that connects the high pressure chamber and the low pressure chamber is held in the blocking position by a spring,
The pilot pressure chamber is moved to a communicating position by the pilot pressure in the pilot pressure chamber opened at the end face, and a pilot poppet is provided which is actuated by high pressure oil in the high pressure chamber to communicate the high pressure chamber and the pilot pressure chamber, and the pilot pressure chamber is connected to an orifice. It communicates with the low pressure chamber through the spool, which has a simple structure and can increase the thrust of the main spool.

〔Example〕

As shown in FIG. 1, a main spool 23 that disconnects the high pressure chamber 21 and the low pressure chamber 22 is fitted into the valve body 20. 1
It consists of a second large diameter part 26 facing the large diameter part 24 and a pilot pressure chamber 25, and a small diameter part 27 connecting the first and second large diameter parts 24 and 26. In addition to communicating with the low pressure chamber 22, the main spool 23 is pushed to the right by a spring 30 and is connected to the high pressure chamber 2.
1 and the low pressure chamber 22 are held in a position where the first large diameter portion 24 blocks them, the first oil hole 28 and the high pressure chamber 21 communicate with each other through the hole 31, and the pilot poppet 32 is connected to the periphery of the hole 31 by a spring 33.
In other words, it is crimped to the seat seat 34 to shut it off, and the pilot poppet 32 has a hole 31 with a diameter d connected to the high pressure chamber 2.
1 acts, the second large diameter portion 26 has a diameter D (Da
d).

When the pressure P in the high pressure chamber 21 exceeds the set pressure 20 determined by the pressure receiving area of the pilot poppet 32 and the spring force of the spring 33, the pilot poppet 32 is pushed down and the high pressure chamber opens as shown in FIG. Pressure P inside 21
, flows into the pilot pressure chamber 25 from the oil hole 28, and at the same time, the pressure oil that flows into the oil hole 28 flows through the orifice 29 to the low pressure chamber 22 and drains into the tank 35.
Pressure P2 is generated when passing through the orifice 29, and this pressure P2 acts on the right end surface 26a of the second large diameter portion 2B to push the main spool 23 to the left against the spring 30, and the high pressure chamber 21
The high-pressure oil inside is transferred from the notch groove 36 of the first large-diameter portion 24 to the low-pressure chamber 2.
2, the pressure P1 in the high pressure chamber 21 decreases to the set pressure Po.

When the pressure P in the high pressure chamber 21 drops below the set pressure P0, the pilot poppet 32 is pressed against the seat seat 34 by the spring 33, and the pressure oil in the high pressure chamber 21 no longer flows into the oil hole 28. When the pressure P2 is no longer generated, the main spool 23 is moved to the right by the spring 30 to the state shown in FIG.

Thereby, the pressure P in the high pressure chamber 21 can be maintained at the set pressure PG determined by the pressure receiving area of the pilot poppet 32 and the spring force of the spring 33.

The above embodiment has the following effects.

(2) The pilot poppet 32 receives the high pressure in the high pressure chamber 21 and releases the high pressure oil, so the structure is simple.

2. Since the main spool 23 receives pilot pressure on the right end surface 26a of the second large diameter portion 26, the pressure receiving area becomes large and the thrust becomes large, so that the influence of sliding resistance when the main spool is operated is reduced. Therefore, the hysteresis of the pressure override characteristic can be reduced.

3. High-pressure oil is relieved from the notched groove 36 of the main spool 24, so the passage area change during relief is small, reducing hydraulic pulsation, and the shape of the notched groove 36 allows the passage area change to be set arbitrarily, reducing hydraulic pulsation. can be arbitrarily made smaller.

4. Since the orifice 29 is provided in the middle of the pilot relief of high-pressure oil to the low-pressure chamber 22, that is, in the oil hole 28, surface pressure pulsations in the pilot pressure chamber 25 are less likely to occur, and the diameter of the orifice 29 can be reduced. By changing the pressure override characteristics, you can change the pressure override characteristics. For example, if the diameter of the orifice 29 is increased, the pressure override characteristic will be decreased, and if the diameter of the orifice 29 is decreased, the pressure override characteristic will be increased.

5. The structure is simple, making it easy to make into a cartridge, and it is also inexpensive.

FIG. 3 shows a second embodiment, in which a spring receiver 37 of a pilot poppet 32 is made slidable to form a pressure receiving chamber 38, and pressure fluid is supplied to this pressure receiving chamber 38 from the outside to cause the spring receiver 37 to slide. This allows the set load of the spring 33 to be adjusted, thereby making it possible to vary the pressure within the high pressure chamber 21.

In this case, the pilot poppet 32 is a sliding type having a hole 32a, and the hole 32a connects the high pressure chamber 21 and the oil hole 2.
8.

FIG. 4 shows a third embodiment, in which a sleeve 40 is attached to the valve body 2o.
The main spool 23 is fitted into the sleeve 4o, and the main spool 23 is biased to the right by the spring 3o to press the cone sheet 41 onto the seat seat 40a of the sleeve 40, thereby forming the high pressure chamber 21. and the low pressure chamber 22 is shut off.

A cap 42 is screwed onto the right end of the sleeve 40 to form a pilot pressure chamber 25 and a main spool 25.
3 is provided with a pilot poppet 32 that disconnects the high pressure chamber 21 and the pilot pressure chamber 25, and the pilot pressure chamber 25 is communicated with the tank 35 through the orifice 29.

If this is the case, the pilot poppet 32 will open due to the pressure in the high pressure chamber 21, and high pressure oil will flow out into the tank 35 through the orifice 29. Pressure will be generated in the pilot pressure chamber 25, causing the main spool 23 to resist the spring 30. The cone seat 41 is moved away from the seat seat 40a and the high pressure oil in the high pressure chamber 21 flows out into the low pressure chamber 22 through the notched groove 36, allowing the pressure in the high pressure chamber 21 to be maintained at the set pressure. .

Furthermore, since the poppet 32 is structured so as to face the high pressure chamber 21 through the passage 23a within the main spool 23, it can be easily integrated and miniaturized.

FIG. 5 shows a fourth embodiment, in which the main spool 23 is provided with a pilot poppet 32 that disconnects the high pressure introduction hole 43 and the pilot hole 44, and when the pilot poppet 32 is opened, the high pressure oil in the high pressure chamber 21 flows into the orifice. 29 to the low pressure chamber 22 to generate pressure, and the pressure flows through the pilot hole 44 to the pilot pressure chamber 2 of the main spool 23.
5 and is pushed to the right against the spring 30, and as the cone seat 45 separates from the seat seat 46, the notch groove 36
The high pressure chamber 21 and the low pressure chamber 22 are communicated with each other.

Further, as shown in FIG. 6, a hole 47 having two orifices may be formed in the main spool 23, and high pressure oil may flow into the low pressure chamber 22 through this hole 47.

[Effects of the Invention] Since the pilot poppet 32 operates to receive high pressure oil in the high pressure chamber 21 and supply the high pressure oil to the pilot pressure chamber 25, the structure is simplified.

Since the pilot pressure acts on the end face of the main spool 23, the pressure-receiving area becomes larger, the thrust becomes larger, and the hysteresis becomes smaller.

[Brief explanation of drawings]

FIG. 1 is a sectional view of the first embodiment of the present invention, FIG. 2 is an explanatory diagram of operation, and FIGS. 3, 4, 5, and 6 are sectional views of the second, third, and
4th and 5th embodiments, and FIG. 7 is a sectional view of the conventional example. 21 is a high pressure chamber, 22 is a low pressure chamber, 23 is a main spool, 25
is a pilot pressure chamber, 29 is an orifice, 30 is a spring,
32 is the pilot poppet.

Claims (1)

[Claims] Main spool 23 that disconnects high pressure chamber 21 and low pressure chamber 22
and a spring 30 that holds this main spool 23 in the blocking position.
A pilot pressure chamber 25 opens at the end face of the main spool 23 that pushes the main spool 23 to the communicating position against this spring force, and connects the pilot pressure chamber 25 and the high pressure chamber 22 to the high pressure inside the high pressure chamber 22. A pressure control valve comprising a pilot poppet 32 that is interrupted by oil and an orifice 29 that communicates a pilot pressure chamber 25 with a low pressure chamber 22.