JPH08100806A - Hydraulic control circuit - Google Patents

Abstract

PURPOSE: To simplify a device without requiring any confluent control valve in joining pumps connected with respective two circuit systems. CONSTITUTION: A first and a second confluent control valves 28, 29 are opened and closed to a boom cylinder 32 to perform confluent control and a third confluent control valve 40 is opened and closed to an arm cylinder 44 to perform confluent control.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydraulic control circuit having a plurality of circuit systems such as a power shovel.

[0002]

2. Description of the Related Art FIG. 4 shows a hydraulic circuit of a conventionally known power shovel. This circuit includes a first pump 1, a second pump 2 and a sub pump 3 for remote control.
It has. Then, one circuit system connected to the first pump 1 is provided with four control valves 4 to 7. Each of these control valves is normally open, and when they are all in the normal position, the first
The oil of the pump 1 returns to the tank 9 through the tank passage 8. Also, in the other circuit system connected to the second pump 2,
Control valves 10 to 13 similar to the one circuit system
And when all of them are in the normal position, the second
The oil of the pump 2 returns to the tank 9 through the tank passage 14.

[0003]

The above-mentioned conventional drawbacks as described above are that control valves 5 and 13 for joining the oils of the first and second pumps 1 and 2 must be provided. In other words, the boom cylinder B is controlled by the other control valve 12, but for speeding up etc.,
Combine the oils of the first and second pumps. Therefore, the control valve 5 for merging must be provided in the one circuit system. Also, for the same reason, the arm cylinder A had to be provided with the control valve 13 for merging in the other circuit system. For this reason, the number of control valves in each circuit system increases, which complicates the structure, increases the piping resistance, and causes the size of the device to increase. An object of the present invention is to provide a hydraulic control circuit in which the number of control valves is reduced by simply incorporating a simple merging control valve in order to join the oils of the two circuit systems without requiring a special control valve. .

[0004]

The present invention comprises one circuit system connected to a first pump and the other circuit system connected to a second pump, and each circuit system is a normal circuit for controlling a predetermined actuator. A hydraulic control circuit in which a plurality of open control valves are provided and the specific control valve is switched by the pilot pressure from the sub-pump to merge the oils of the first and second pumps and supply them to the actuator connected to the control valve. Is assumed.

Based on the above-mentioned control circuit, the present invention has a first merging passage connected in parallel to each control valve of one circuit system and connected to a specific actuator of the other circuit system, A specific control valve that controls the specific actuator of the other circuit system and that is switched by the pressure action of the pilot pressure chamber, and a pilot chamber of the specific control valve that is located at the most downstream side of the one circuit system. The second merging control valve that opens and closes under the action of the same pilot pressure as the acting pilot pressure and the other circuit system that closes the open passage when the pilot pressure acts on the pilot pressure chamber, Sometimes controls a third merging control valve that opens an open passage and a specific actuator of one circuit system, and
A specific control valve having a pilot pressure chamber that communicates with the pilot pressure chamber of the merge control valve, and a second merge flow that connects the upstream side of the third merge control valve to the inflow port side of the specific actuator of one circuit system. Passage and this second
It is characterized in that it is provided in the merging passage and is provided with a check valve that allows only the flow from the upstream side of the third merging control valve to the inflow port side of the specific actuator of one circuit system.

[0006]

Since the present invention is configured as described above, when the control valve for controlling the specific actuator of the other circuit system is switched, the pilot pressure at that time is changed to the second value.
It acts on the pilot chamber of the merge control valve. The second merge control valve is closed by the action of this pilot pressure. Therefore,
The oil discharged from the first pump is supplied to the specific actuator of the other circuit system via the first merging passage.
Also, when the control valve that controls a specific actuator of one circuit system is switched, the pilot pressure at that time also acts on the pilot chamber of the third merging control valve, and
Close the merge control valve. If the third merging control valve is closed in this way, the pressure oil from the second pump, which is supplied to the open passage of the other circuit system, passes through the second merging passage, and the above-mentioned identification of one circuit system is performed. Is supplied to the actuator.

[0007]

1 is a circuit diagram shown for a power shovel, in which a first pump 15, a second pump 16 and a sub-pump 17 for remote control are provided. Then, one circuit system connected to the first pump 15 is provided with three control valves 18 to 20, and the other circuit system connected to the second pump 16 is also provided with three control valves 21 to 23. It is provided. And the control valve 1
Each of 8 to 23 is normally open, and the control valves 18 to 20 and 21 to 23 in both circuit systems are set.
Are connected in tandem via their open passages 24, 25. At the same time, each of them is connected in parallel via parallel passages 26 and 27. The first merging control valve 28 connected in parallel with the control valve is provided on the most upstream side of one circuit system as described above,
A second merging control valve 29 connected in tandem with the control valve is provided on the most downstream side. In the normal position, the second merging control valve 29 communicates the open passage 24 with the tank 31 via the check valve 30, and at the switching position (left side in the drawing) of the open passage 24 and the tank. The connection with 31 is cut off.

Therefore, when all of the control valves 18 to 20 and the second merging control valve 29 are in the normal position, the oil of the first pump 15 returns to the tank 31 as it is. On the other hand, the first merging control valve 28 is in the process of passage between the first pump 15 and the boom cylinder 32, cuts off the communication between the both in its normal position, and in the switching position (lower position in the drawing) of the check valve. The two are connected to each other via 33. And these first and second
The merging control valves 28 and 29 are in a relationship interlocking with the control valve 22 that controls the boom cylinder 32 in the other circuit system. That is, this trawl valve 22
Boom cylinder 3 of pilot passages 34, 35 of
2 and the pilot pressure chambers 36, 3 of the first and second merging control valves 28, 29, which become high pressure when the second valve 2 is extended.
It communicates with 7. Therefore, the control valve 22
To the right position in the drawing, the oil in the second pump 16
It flows into the bottom side of the boom cylinder 32 and extends it. At the same time, the pressure from the sub-pump 17 is first,
2 The merging control valves 28 and 29 flow into the pilot pressure chambers 36 and 37 to switch the merging control valves 28 and 29. When the first and second merging control valves 28 and 29 are switched, the communication between the first pump 15 and the tank 31 is cut off, and the first pump 15 and the bottom side of the boom cylinder 32 are connected. As a result, the oils of the first and second pumps 15 and 16 merge on the bottom side of the boom cylinder 32 through the first merging passage 28 and the check valve 39.

On the most downstream side of the other circuit system,
A third merging control valve 40 connected in tandem with the control valves 21 to 23 is provided. This third merging control valve 4
No. 0 has the same configuration as that of the second merging control valve 29. Therefore, as long as each of the control valves 21 to 23 and the third merging control valve 40 is in the normal position, the oil of the second pump 16 passes through the check valve 41. Then it returns to the tank 31 as it is. Further, a second merging passage 42 is connected to the open passage 25 upstream of the third merging control valve 40, and the second merging passage 42 passes through the check valve 43 to the bottom of the arm cylinder 44. It communicates with the side. And this 3rd confluence control valve 40 is the said one circuit system,
It is in a relationship of interlocking with the control valve 19 that controls the arm cylinder 44. That is, of the pilot passages 45, 46 of the control valve 19, the arm cylinder 44
The pilot passage 45, which has a high pressure when the valve is extended, communicates with the pilot pressure chamber 47 of the third merging control valve 40.

Therefore, when all of the control valves 21 to 23 of the other circuit system are held in the normal position and the control valve 19 of the one circuit system is switched to the left side position in the drawing, the oil of the first pump 15 is released from the arm cylinder 44. Flows into the bottom side of. At the same time, the pressure from the sub-pump 17 flows into the pilot pressure chamber 47 of the third merging control valve 40 and switches it. When the third merging control valve 40 is switched, the communication between the second pump 16 and the tank 31 is cut off, so that the oil of the second pump 16 passes through the second merging passage 42 to the bottom side of the arm cylinder 44. Inflow. Also,
The first merging control valve 28 is provided as described above because when the actuator connected to the control valve of one circuit system is operated in the state where the boom cylinder 32 is stopped, the pressure oil of the first pump 15 is This is to prevent the supply to the boom cylinder 32. If the first merging control valve 28 is not provided, if any one of the control valves of the one circuit system is switched, the load pressure of the actuator connected thereto also acts on the boom cylinder 32 to move it. In addition, the first merging valve 28
Since the merging passage 38 is opened and closed, the actuator of the first circuit system and the boom cylinder 32 can be operated simultaneously.

FIG. 2 specifically shows the one circuit system. As is apparent from FIG. 2, the first merge control valve 28 has the first main poppet 48 as a main element. That is, the first merging control valve 28 has a communication hole 50 formed in a portion where the open passage 24 and the pump port 49 that directly communicates with the first pump 15 meet. The communication hole 50 allows the pump port 49 to communicate with the first merging passage 38, and the communication hole 50 has the first hole.
A main poppet 48 is provided. The first main poppet 48 has an orifice 51 formed on its pressure receiving surface, and pressure oil from the pump port 49 is introduced into the back pressure chamber 52 through the orifice 51. The back pressure chamber 52 of the first main poppet 48 communicates with the tank passage 54 via a valve mechanism including a ball 53, or the communication is blocked. That is, the valve mechanism is opened / closed with the movement of the opening / closing member 55. When the pilot pressure from the sub-pump 17 is introduced into the pilot pressure chamber 36, the opening / closing member 55 moves in a direction to push up the ball 53, The valve mechanism is open. Therefore, when the valve mechanism is open, the back pressure chamber 52 becomes the tank pressure, so that the first main poppet 48 opens the communication hole 50 by the pressure action of the first pump 15. When the first main poppet 48 is opened, oil from the pump port 49, that is, the first pump 15 flows to the first merging passage 38,
As described above, it merges with the oil from the second pump 16 and flows into the boom cylinder 32.

On the other hand, when the pilot pressure chamber 36 reaches the tank pressure, the ball 53 descends and the valve mechanism closes. When the valve mechanism is closed, pressure is accumulated in the back pressure chamber 52, and the communication hole 50 is closed by the action of the spring 56. Therefore, the oil of the first pump 15 stops flowing to the boom cylinder 32. On the other hand, the second merge control valve 29 has a second main poppet 57 as a main element, and the second main poppet 57 is
A communication hole 58 that connects the most upstream open passage 24 and the tank passage 54 is opened and closed. That is, the second main poppet 57 has an orifice 5 on its pressure receiving surface.
9 is formed so that the pressure oil from the open passage 24 is introduced into the back pressure chamber 60 through the orifice 59. The back pressure chamber 60 of the second main poppet 57 communicates with the tank passage 54 via the valve mechanism including the piston 61 and the escape passage 62, or the communication is blocked. That is, when the pilot pressure is supplied to the pilot pressure chamber 37, the communication between the back pressure chamber 60 and the escape passage 62 is blocked by the action of the piston 61. Therefore, the pressure oil introduced from the orifice 59 stays in the back pressure chamber 60, and the communication hole 58 is closed by the action of the spring 63. Communication hole 58
If the control valves 18 to 20 are closed, the pressure oil from the pump port 49 pushes the first main poppet 48 open as described above even if the control valves 18 to 20 are held in the normal position, and the first merging passage 38 is opened. Flow to.

When the pilot pressure chamber 37 reaches the tank pressure,
The valve mechanism including the piston 61 is opened by the pressure in the back pressure chamber 60, and the back pressure chamber 60 is communicated with the tank passage 54 through the escape passage 62. Therefore, the second main poppet 57 moves against the spring to connect the open passage 24 to the tank passage 54. In this one circuit system, the first merging control valve 28 is connected in parallel with the control valves 18 to 20, so that the first merging control valve 28 can be switched by switching any of the control valves. it can. The configuration of the third merging control valve 40 shown in FIG. 3 is exactly the same as that of the second merging control valve 28. Therefore, the details thereof will be omitted, and the same reference numerals will be given to the respective elements of the second merge control valve in the drawings. However, in the other circuit system, the open end 64 of the second merging passage 42 is connected to the most downstream open passage 25. Therefore, unless pressure is applied to the pilot pressure chamber 47, the oil from the open passage 25 flows out into the tank passage 54 as it is and does not flow into the second joining passage 42.

[0014]

Therefore, according to the control circuit of the present invention, it is not necessary to specially provide a control valve for merging, and the circuit can be simplified. Moreover, the hydraulic oils of both circuit systems can be combined with each other. Further, since the respective merging control valves can be switched by the pilot pressure, there is no problem that the arrangement of the respective merging control valves is limited. In other words, if the merging control valve is mechanically linked with another control valve, the arrangement of the merging control valve will be limited, but in the case of the present invention, there is no such restriction.

[Brief description of drawings]

FIG. 1 is a circuit diagram of a first embodiment.

FIG. 2 is a sectional view specifically showing one circuit system.

FIG. 3 is a cross-sectional view of the other circuit system.

FIG. 4 is a circuit diagram of a conventional device.

[Explanation of symbols]

 15 1st pump 16 2nd pump 17 Sub pump 18 Control valve of one circuit system 19 Control valve of one circuit system 20 Control valve of one circuit system 21 Control valve of the other circuit system 22 Control valve of the other circuit system 23 Control valve of the other circuit system 24 Open passage 25 Open passage 29 Second merging control valve 37 Pilot pressure chamber 38 First merging passage 40 Third merging control valve 42 Second merging passage 47 Pilot pressure chamber

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[Procedure amendment]

[Submission date] December 9, 1994

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be amended] Claims

[Correction method] Change

[Correction content]

[Claims]

Claims (1)

[Claims] 1. A circuit system comprising one circuit system connected to a first pump and the other circuit system connected to a second pump, each circuit system being provided with a plurality of normally open control valves for controlling a predetermined actuator. , A specific control valve is switched by the pilot pressure from the sub-pump to join the oils of the first and second pumps to the actuator connected to the control valve and supply the combined hydraulic oil. A first merging passage connected to each control valve in parallel and connected to a specific actuator of the other circuit system, and the specific actuator of the other circuit system are controlled, and the pressure action of the pilot pressure chamber is controlled. There is a specific control valve that switches with
The second merging control valve that opens and closes under the action of the same pilot pressure as the pilot pressure acting on the pilot pressure chamber of the specific control valve, and the pilot pressure acts on the pilot pressure chamber in the other circuit system. When the open aisle is closed when, and the open aisle is opened at other times
A confluence control valve, a specific control valve that controls a specific actuator of one circuit system, and has a pilot pressure chamber that communicates with the pilot pressure chamber of the third confluence control valve; and an upstream of the third confluence control valve. A second merging passage that communicates the side with the inflow port side of the specific actuator of the one circuit system, and a second merging passage that is provided in the second merging passage, A hydraulic control circuit having a check valve that allows only the flow to the inflow port side.