JPH01164875A - control valve - Google Patents

Abstract

PURPOSE:To prevent the control operation from being disturbed due to variations in the speed of motion of a spool caused by leakage of hydraulic oil from the fitting and sliding section between a sleeve and the spool by forming a drain passage from the fitting section to an low pressure port. CONSTITUTION:A drain passage for discharging hydraulic oil having entered from the high pressure port 5 side to the low pressure port 6 side is formed in the fitting section of a sleeve 1 and a spool 2 in a control valve. Accordingly, when the spool 2 is slid and displaced in association with feed and discharge of hydraulic oil to and from a rear chamber 3 by a pilot circuit 9, it is possible to eliminate the affection by leakage of hydraulic oil from the high pressure port side to the rear chamber 3.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a control valve for controlling pressure oil in, for example, a hydraulic elevator, and particularly to improving the operating accuracy thereof.

[Conventional technology]

Fig. 3 is a sectional view showing a conventional control valve similar to the one shown in, for example, Japanese Utility Model Application Publication No. 51-200774. (2) is a spool provided in the valve chamber (1a) so as to be slidable in the axial direction; (3) is a sleeve (1);
), the first back chamber (4) is configured at one end of the first back chamber (3
), a second back chamber (5) is formed in the other end of the sleeve (1) opposite to the valve chamber (1a);
The first back chamber (3) is connected to the high-pressure bow located at
(61 is a low pressure port that is provided in the sleeve ill and communicates with the valve chamber (1a), and is placed opposite the high pressure port (5) near the second back chamber (2)) i71 is the concave part of the sleeve (2) Choke (8) formed by high pressure port (5)
is a push spring installed in the second back chamber (4) and fully presses the spool (2), (9) is the first pilot circuit that communicates with the first back chamber (3), (1G is the second back chamber (4) ), +111 is connected to the first pilot circuit (
9) Variable throttle valve provided in.

@ is an oil tank provided at the end of the circuit on the low pressure port (6) side.

The conventional control valve is configured as described above, and the pressure oil flows from the high pressure port (5), the choke (7), and the low pressure port (6) to the oil tank a.
Pressure oil is introduced from the first pilot circuit (9) into the first back chamber (3) via the variable throttle valve Ut, and from the second back chamber (4) to the second pilot circuit (4). A drain circuit is formed in the drain circuit. And variable throttle valve α
The force of the pressure oil acting on the first back chamber (3) side of the spool (2) due to the operation of υ etc. and the force acting on the spool (2) due to the push spring (8)
) by slidingly displacing the area of the choke (7),
Choke (7) Flow rate of pressure oil passing through all and high pressure port (
5) High pressure bow [5] due to changes in side pressure;
The pressure on the low pressure port (6) side is controlled.

[Problem that the invention seeks to solve]

In the conventional control valve as described above, pressure oil leaks from the gap between the fitting part of the sleeve (1) and the spool (2) to the first back chamber (3) at the high pressure port (5), but the amount of leakage is small. There is a problem in that the operating speed of the spool (2), which slides and is displaced, changes due to changes in the pressure on the high pressure port (5) side and changes in the viscosity of the pressure oil, making it impossible to obtain the desired control action. Ta.

In addition, in order to prevent leakage of pressure oil from the fitting part of the sleeve (1) and the spool (2), it is possible to provide a sealing material such as an O-ring on the sleeve (1), etc.; 2) As the sliding resistance increases.

Since the sliding resistance of the spool (2) changes due to changes in the sealing pressure and changes in the temperature of the pressure oil, the control action becomes even more unstable.

The present invention was made to solve this problem, and prevents disturbances in the control action due to changes in the operating speed of the spool due to leakage of pressure oil from the fitting portion of the sleeve and spool, thereby ensuring good operation. The purpose is to obtain a control valve that

[Failure to solve the problem]

The control valve according to the present invention is provided with a low-pressure port side hedrain flow path from the fitting and sliding portion of the sleeve and the spool. flows out to the low pressure port side through the drain flow path and no longer flows into the back chamber of the valve chamber.

〔Example〕

FIG. 1 is a diagram corresponding to FIG. 3 showing an embodiment of the control valve according to the present invention, and in FIG. 2, the same reference numerals as in FIG. 1 indicate the same parts.
(13 is a groove disposed on the relative sliding surface of the valve chamber (1a) and the spool (2) and recessed in the spool (2).
The spool (2) has an annular shape perpendicular to the axis of the spool (2) and is provided on the outer periphery of the surface of the spool (2). I is provided at a position opposite to the low pressure port (6) of the spool (2) and the spool (2)
α9 is the through hole provided across the axis of the spool (
2) A through hole provided along the axis of the spool (2) from the bottom of one side of the annular groove αj perpendicular to the axis to the bottom of the other side; This is a drain flow path consisting of a conduit opening into the through hole α9, a groove α1 through hole +141α9, and a conduit αe.

In the control valve configured as described above, the sleeve (1
) and the spool (2) from the high pressure port (5) side enters the groove α3 and flows into the drain flow path (171
It flows out to the low pressure port (6) side through the first back chamber (3
).

In addition, the pressure oil from the first back chamber (3) from the first pilot circuit (9) also enters the fitting sliding part of the sleeve (1) and spool (2) through the drain passage system and into the low pressure port ( 6) Outflow to the side. For this reason, the spool (2) is displaced by sliding due to the supply and discharge of pressure oil to the first back chamber (3) by the first pilot circuit (9), but the influence of the leakage pressure oil from the high pressure port (5) side is (2) The problem of sliding displacement is eliminated. Therefore, a control valve is realized in which a normal sliding displacement operation of the spool (2) can be obtained and a required control action of the pressure oil can be obtained. In addition, if you use a spool like this (
The normal sliding displacement operation in 2) is similar to that obtained when a sealing material is interposed in the fitting and sliding part of the sleeve (1) and spool (2), and it is a simple device with low sliding resistance. With this configuration, the desired effect can be obtained inexpensively and easily with high precision.

FIG. 2 shows another embodiment of the control valve according to the present invention. In FIG. 2, the same reference numerals as in FIG. This groove is disposed on the surface and recessed in the valve chamber (1a), has an annular shape perpendicular to the axis of the spool (2), and is provided around the inner surface of the valve chamber (1a). αe is provided in the sleeve +1) and one end has a groove α
The other end is a conduit opening on the bottom surface of the pipe, and the other end is a conduit opening on the low pressure port (6) side.

That is, in this embodiment as well, the pressure oil that entered the fitting sliding portion of the sleeve (1) and spool (2) from the high pressure port (5) side enters the groove 0 and flows from the drain flow path aη to the low pressure port (6). It flows out to the side. Therefore, although a detailed explanation will be omitted, it is clear that the same effect as the embodiment shown in FIG. 1 can be obtained in this embodiment as well.

〔Effect of the invention〕

As described above, the present invention has all stages of a drain flow path for causing pressurized oil that has entered the fitting sliding portion of the sleeve and spool from the high pressure port side to flow out to the low pressure port side. Therefore, when the spool slides and displaces due to the supply and discharge of pressure oil to and from the back chamber by the pilot circuit, the spool slides and displaces without being affected by the pressure oil leaking from the high pressure port side to the back chamber. The present invention provides a control valve that can perform displacement operations and easily obtain the required control action.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing one embodiment of the control valve according to the present invention, FIG. 2 is a view corresponding to FIG. 1 showing another embodiment of the control valve according to the invention, and FIG. 3 is a conventional control valve. This is a diagram equivalent to Figure 1. In the figure, (1) is the sleeve, (2) is the spool, (
3) is the first back chamber, (5) is the high pressure port, and 6) is the low pressure port. (7) is the choke, (9) is the first pilot circuit, σ3
is a groove. αη is a drain flow path. In addition, the same parts or corresponding parts in FIG. 9 are indicated by the same reference numerals.

Claims (1)

[Claims] A spool that slides in the axial direction is provided in the sleeve, pressure oil is introduced by a pilot circuit into a back chamber facing the end of the spool, and the spool is slidably displaced by operating the supply and discharge of this pressure oil. , by changing the area of the choke part of the flow path formed by both the sleeve and the spool,
In the control valve that controls the pressure or flow rate of the pressure oil on the high pressure port side provided on one side of the choke part and the low pressure port side provided on the other side, one of the two relative sliding surfaces. an annular groove that is recessed in the sleeve and that extends along the circumferential surface and intersects the axis; one end of the groove is opened in the sleeve; A control valve characterized in that the control valve is provided with a drain flow path whose other end is open to the low pressure port side.