JPH0755030A - Directional control valve for flow rate assistance - Google Patents

Abstract

PURPOSE:To assist two actuators with pressure oil, to make a directional control valve compact and to flow return oil from one of the actuators out to a tank. CONSTITUTION:In a spool 21 of a valve block 20, first and second spools 22, 23 are fit and inserted, this first spool 22 is positioned at a neutral position by a first spring 36 and devised to move to a position to supply to an actuator by pressure oil of a second pressure part 47, the second spool 23 is positioned at a neutral position by a second spring 41 and positioned at a position to flow return oil out to a tank by pressure oil of a first pressure chamber 42, and it is positioned at a position to supply pressure oil to the actuator by pressure oil of a third pressure chamber 52.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is used in a pressure oil supply device for supplying the discharge pressure oil of a hydraulic pump to a plurality of actuators by a plurality of directional control valves and supplying the discharge pressure oil of the hydraulic pump to a plurality of actuators. The present invention relates to a flow control directional control valve that operates at high speed.

[0002]

2. Description of the Related Art As a pressure oil supply device for supplying pressure oil discharged from a hydraulic pump to a plurality of actuators, a plurality of directional control valves are provided in a discharge passage of the hydraulic pump to supply the pressure oil to a plurality of actuators. For example, a boom cylinder, an arm cylinder, which is provided with a boom directional control valve, an arm directional control valve, a bucket directional control valve, a swing directional control valve, and a left and right traveling directional control valve in the discharge passage of a hydraulic pump. A hydraulic circuit of a power shovel that supplies pressure oil to a bucket cylinder, a swing motor, and a left and right traveling motor is known.

The directional control valves used in such a hydraulic circuit have the same size in order to make them common, and the maximum flow rates that can be supplied to the actuators are the same, and the maximum operating speeds of the actuators are the same. Therefore, when a specific actuator is operated at high speed, a flow rate support directional control valve is provided so that a large flow rate can be supplied to the specific actuator.

For example, in the hydraulic circuit of the above-mentioned power shovel, since it is necessary to operate the boom cylinder and the arm cylinder at high speed, the boom flow direction control valve and the boom direction control valve are arranged in parallel with the boom direction control valve and the arm direction control valve. A valve and arm flow direction control valve are installed to supply a large flow rate to the boom cylinder and arm cylinder.

[0005]

When a large flow rate is to be supplied to a specific actuator as described above, directional control valves for supporting the flow rate are required as many as the specific actuators for supplying the large flow rate. Since the directional control valve has a spool fitted in the valve block, the number of valve blocks becomes large, the pressure oil supply device becomes large, and the installation space becomes large.

Incidentally, as shown in Japanese Utility Model Laid-Open No. 4-134969, two spools are fitted and inserted in one valve block,
A valve is known that controls the opening and closing of two circuits by moving the two spools. In this valve, the two spools are biased in one direction by springs and the pilot pressure is applied to the springs. Since it is a structure that pushes in the other direction against, the circuit opens and closes the circuit to allow the pressure oil to flow, but it only has the function of preventing the pressure oil from flowing.

For this reason, when the above-mentioned valve is used as a boom support directional control valve or an arm support directional control valve, pressure oil is supplied to the boom cylinder or arm cylinder, or the pressure oil is supplied. It just stops and does not function for the return oil flow from the boom cylinder and arm cylinder.

However, since the return oil from the actuator flows out into the tank through the meter-out opening of the directional control valve, when the return oil of the actuator is large, the flow resistance becomes large and the back pressure becomes large. Large hydraulic horsepower and large circuit loss. For example, when pressure oil is supplied to the compression chamber of the arm cylinder to perform a compression operation, a large amount of oil is returned from the expansion chamber, resulting in a large back pressure and thus a large driving pressure.

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

[0010]

First and second spools 22 and 23 are fitted on the left and right sides of a spool hole 21 of a valve block 20, and an intermediate port 24 is provided on the left and right middle portion of the spool hole 21.
To form the opposite ends 2 of the first and second spools 22 and 23.
A first pressure receiving portion 42 opened to 2a and 23a, and a first spool 22 that communicates with and is blocked by the first spool 22.
The pump port 27 and the first actuator port 29 are formed, and the second spool 23 communicates with the spool hole 21 thereof.
The second pump port 28, the second actuator port 30, and the second tank port 32, which are shut off, are formed, and
The spool 22 is held in a neutral position where each port is blocked by the first spring 36, and is moved to the first position where the first pump port 27 and the first actuator port 29 communicate with each other by the pressure oil of the second pressure receiving portion 47. In addition, the first spool is communicated with the left end chamber 36a of the spool 22 so as not to be affected by the pressure of the first pressure receiving chamber, and the second spool 23
Is held at a neutral position where each port is blocked by the second spring 41, and the second pump port 28 is closed by the pressure oil in the third pressure receiving chamber 52.
And the second actuator port 30 are communicated with each other and the second actuator port 30 and the second tank port 32 are shut off to a first position, and the second actuator port 30 is moved to the second position by the pressure oil in the first pressure receiving chamber 42. A flow control directional control valve configured to communicate with the tank port 32 and move to a second position that blocks the second actuator port 30 and the second pump port 28.

[0011]

[Operation] By moving the first spool 22, pressure oil can be supplied to the first specific actuator, and by moving the second spool 23, pressure oil can be supplied to the second specific actuator. 1st and 2nd spool 22,2
Since 3 is provided in one valve block 20, it can be made compact, and further by moving the second spool 23 to the second position, the return oil of the second specific actuator can flow out to the tank. Therefore, a large flow rate can be discharged to the tank, and the second specific actuator can be operated smoothly.

[0012]

[Example] As shown in Fig. 1, a pair of hydraulic pumps 1
The discharge path 1a of the
Inlet of the left traveling directional control valve 4, the turning directional control valve 5, the boom directional control valve 6, the right traveling directional control valve 7, the bucket directional control valve 8, and the flow rate assisting directional control valve 9 according to the present invention. The hydraulic oil is supplied to the arm cylinder 10, the left traveling motor, the swing motor, the boom cylinder 11, the right traveling motor, and the bucket cylinder by the respective directional control valves. The flow control directional control valve 9 includes an arm portion 9a and a boom portion 9b. The arm portion 9a is connected to the extension chamber 10a of the arm cylinder 10 by an arm support circuit 12 and the boom portion 9b is a boom. The support circuit 14 is connected to the extension chamber 11a of the boom cylinder 11. Reference numeral 15 is a lock valve.

The details of the flow control directional control valve 9 are shown in FIG.
It will be described based on. Spool hole 21 of valve block 20
The first spool 22 and the second spool 23 are slidably inserted in the left and right of the, and an intermediate port 24 is formed in the left and right intermediate portion of the spool hole 21. First and second outlet ports 25, 2
6, first and second pump ports 27 and 28, first and second actuator ports 29 and 30, and first and second tank ports 31 and 32 are respectively formed, and the first spool 22 has a first outlet port 25. Communicates with the first pump port 27.
A first small diameter portion 33 and a first cutout 34 for blocking and a second small diameter portion 35 for communicating and blocking the first actuator port 29 and the first tank port 31 are formed, and each port is blocked by a first spring 36. Is held in a neutral position, the second spool 23 is connected to the second outlet port 26 and the second outlet port 26.
A third small diameter portion 37 for communicating / blocking the pump port 28, a second notch 38, a fourth small diameter portion 39 for communicating / blocking the second actuator port 30 and the second tank port 32, and a third small diameter portion 39.
The notch 40 is formed and the second spring 41 is formed.
It is held in a neutral position that shuts off each port.

The facing end surfaces 22a and 23a of the first and second spools 22 and 23 face the intermediate port 24 and form a first pressure receiving chamber 42 with the intermediate port 24. The first pressure receiving chamber 42 is formed.
Is communicated with the spring chamber 36a of the first spring 36 through the shaft hole 43 of the first spool 22.

A spring receiving cylinder 44 is fixed to the left end surface 20a of the valve block 20 via a plate 43, and the one end small diameter portion 22b of the first spool 22 is fixed to the plate 4.
3, the piston 46 is bolted, and the piston 46 is fitted into the inner peripheral surface 44a of the spring receiving cylinder 44 to form the spring chamber 36a. The piston 46, the one end small diameter portion 22b, the spring receiving cylinder 44, and the valve block 2
A second pressure receiving chamber 47 is formed between the first end portion 20a of the first spool 22 and the left end face 20a of the second pressure receiving chamber 47, and the first spool 22 is moved to the left via the piston 46 by the pressure oil supplied to the second pressure receiving chamber 47. And

A spring receiving cylindrical body 48 is attached to the right end surface 20b of the valve block 20, and a rod 49 provided in the spring receiving cylindrical body 48 is connected to the second spool 23 and is attached to the rod 49. A second spring 41 is provided between the first and second spring receivers 50, 51 to provide a second
The spool 23 is held in the neutral position, and the first pressure receiving portion 42 is
The second spool 23 is moved to the first position by the pressure oil of No. 3 and is moved to the second position by the pressure oil of the third pressure receiving chamber 52 in the spring receiving cylinder 48.

The valve block 20 is provided with left and right pressure compensating valves 53. The pressure compensating valve 53 is provided with a poppet 55 on a valve body 54, and the poppet 55 is crimped to a valve seat 57 of the valve block 20 by a spring 56. Then, the first and second outlet ports 25 and 26 and the first and second actuator ports 29 and 3
0 is cut off, and the outlet side pressure is set by the load pressure supplied to the spring chamber 56a and the inlet side pressure acting on the poppet 55.

The pressure compensating valve 53 is set by the pump discharge pressure and the highest load pressure when pressure oil is simultaneously supplied to the actuators having different loads, thereby compensating the pressure, thereby supplying pressure oil to the actuators having different loads at the same time. It is provided for each of the directional control valves.

The arm pilot valve 60 uses the pressure oil discharged from the pilot hydraulic pump 61 as the first and second pilot circuits 6
2, 63, and the first and second pilot circuits 6
2, 63 are the first and second pressure receiving portions 3 of the directional control valve 3 for arm.
a and 3b and the first and third pressure receiving chambers 42 and 52, respectively.

The boom pilot valve 64 uses the pressure oil discharged from the pilot hydraulic pump 61 for the first and second pilot circuits 6.
5, 66, and the first and second pilot circuits 6
Reference numerals 5 and 66 denote the first and second pressure receiving portions 6 of the boom directional control valve 6.
The second pilot circuit 66 is connected to a and 6b and communicates with the second pressure receiving chamber 47.

Next, the operation will be described. Boom cylinder 11
When extending and raising the boom. Boom pilot valve 6
4 is operated to output pressure oil to the second pilot circuit 66. As a result, the boom directional control valve 6 is at the raised position a, and the discharge pressure oil of the hydraulic pump 1 is supplied to the extension chamber 11a of the boom cylinder 11. As a result, the boom directional control valve 6 is set to the raised position a, and the discharge pressure oil of the hydraulic pump 1 is supplied to the extension chamber 11a of the boom cylinder 11. At the same time, the pilot pressure oil is supplied to the second pressure receiving chamber 47 of the flow rate control directional control valve 9 to push the first spool 22 to the left to reach the first position, and the first pump port 27 and the first outlet port 25. Communicates with the first small diameter portion 33 and the first notch 34 and the first actuator port 29 and the first tank port 31.
Remains off, the discharge pressure oil of the hydraulic pump 1 is supplied to the extension chamber 11a of the boom cylinder 11 from the first pump port 27, the first outlet port 25, and the first actuator port 29. A large flow rate is supplied to the extension chamber 11a of the column 11.

When the arm cylinder 10 is extended and the arm is lowered to excavate. The arm pilot valve 60 is operated to output pilot pressure oil to the second pilot circuit 63.
As a result, the arm directional control valve 3 is set to the first position b, and the discharge pressure oil of the hydraulic pump 1 is supplied to the extension chamber 10a of the arm cylinder 10. At the same time, the pilot pressure oil is supplied to the third pressure receiving chamber 52 of the flow control direction control 9 for the second control.
The spool 23 is pushed leftward to the first position, the second pump port 28 and the second outlet port 26 are communicated with each other, and the second actuator port 30 and the second tank port 30 remain blocked, so that the hydraulic pump 1 discharge pressure oil is second
The extension chamber 10 of the arm cylinder 10 from the pump port 28, the second outlet port 26, and the second actuator port 30.
Since it is supplied to a, the extension chamber 10 of the arm cylinder 10
Since it is supplied to a, the extension chamber 10 of the arm cylinder 10
A large flow rate is supplied to a.

When the arm cylinder 10 is contracted and the arm is moved up and down to dump. The arm pilot valve 60 is operated to output pilot pressure oil to the first pilot circuit 62.
As a result, the arm directional control valve 3 is set to the second position c, the pressure oil discharged from the hydraulic pump 1 is supplied to the compression chamber 10b of the arm cylinder 10, and the pressure oil in the extension chamber 10a flows out to the tank. At the same time, the pilot pressure oil is supplied to the first pressure receiving chamber 42 of the flow rate control directional control valve 9 so that the second spool 2
3 is pushed rightward to the first position, the second pump port 28 and the second outlet port 26 remain blocked, and the second actuator port 30 and the second tank port 30 move to the fourth small diameter portion 39 and the third notch. 40 communicates with the arm cylinder 10
Pressure oil in the expansion chamber 10a of the second actuator port 3
0, it flows into the tank from the second tank port 32, and a large flow rate flows into the tank from the extension chamber 10a of the arm cylinder 10.

At this time, since the pilot pressure oil supplied to the first pressure receiving chamber 42 is supplied into the spring chamber 36a through the shaft hole 43 of the first spool 22, the first spool 22 does not move left and right.

FIG. 3 shows a second embodiment in which the first actuator 29 and the passage 58 are cut off, and the poppet 55 prevents pressure oil from flowing from the first actuator port 29 to the first outlet port 25. is there.

With this configuration, the pressure oil in the extension chamber 11a of the boom cylinder 11 does not flow out into the tank through the gap between the spool hole 21 and the first spool 22, so that the boom cylinder 11 is contracted by an external force to operate the boom cylinder. It is possible to minimize the natural fall of the valve, and the lock valve 15 shown in FIG. 2 can be omitted.

[0027]

By moving the first spool 22, the first spool 22
Pressure oil can be supplied to the specific actuator, and the pressure oil can be supplied to the second specific actuator by moving the second spool 23.
Since 23 is provided in one valve block 20, it can be made compact. Moreover, by moving the second spool 23 to the second position, the return oil of the second specific actuator can be discharged to the tank, and a large flow rate can be discharged from the second specific actuator to the tank, so that the second specific actuator can be operated. It can operate smoothly.

[Brief description of drawings]

FIG. 1 is an overall explanatory view of a pressure oil supply device showing an embodiment of the present invention.

FIG. 2 is a cross-sectional view showing a first embodiment of the flow control directional control valve of the present invention.

FIG. 3 is a sectional view showing a second embodiment of the flow control directional control valve of the present invention.

[Explanation of symbols]

20 ... Valve block, 21 ... Spool, 22 ... First spool, 23 ... Second spool, 25 ... Intermediate port, 27 ... First pump port, 28 ... Second pump port, 29 ... First
Actuator port, 30 ... Second actuator port, 32 ... Second tank port, 36 ... First spring,
41 ... 2nd spring, 42 ... 1st pressure receiving chamber, 47 ... 2nd
Pressure receiving chamber, 52 ... Third pressure receiving chamber.

Claims (1)

[Claims] 1. A first and a second spool 22, 23 are fitted and inserted into the left and right of a spool hole 21 of a valve block 20, and an intermediate port 24 is formed in the left and right intermediate portion of the spool hole 21 to form a first port.
First pump port 2 which is the first pressure receiving portion 42 opened to the opposite end surfaces 22a and 23a of the second spools 22 and 23 and which is communicated with and cut off from the spool hole 21 by the first spool 22.
7 and the first actuator port 29 are formed, and the second spool 23 is communicated with and cut off by the second spool 23.
The pump port 28, the second actuator port 30, and the second tank port 32 are formed, and the first spool 22 is held at a neutral position where each port is blocked by the first spring 36, and the second pressure receiving portion 47 pressurizes oil. First pump port 27 and first actuator port 29
The first spool 22 is communicated with the left end chamber 36a of the spool 22 so that the first spool 22 is not affected by the pressure of the first pressure receiving chamber 42, and the second spool 23 is The second spring 41 holds the neutral position to shut off each port, and the pressure oil in the third pressure receiving chamber 52 holds the second pump port 28 and the second actuator port 30.
To the first position where the second actuator port 30 and the second tank port 32 are shut off.
Direction for supporting flow rate configured to move the second actuator port 30 to the second tank port 32 by the pressure oil in the pressure receiving chamber 42 and move to the second position where the second actuator port 30 and the second pump port 28 are blocked. Control valve.