JPH0826554B2 - Hydraulic circuit device of hydraulic excavator - Google Patents

Description

TECHNICAL FIELD The present invention relates to a hydraulic circuit device for a hydraulic excavation work machine for a construction vehicle.

[Conventional technology]

In the hydraulic circuit of the hydraulic excavator including the boom, arm, and bucket, as shown in FIGS. 2 and 3, the discharge circuits 3 and 4 of the two hydraulic pumps 1 and 2 are for lifting and lowering the boom. Boom switching valves 5A and 5B and arm switching valves 6A and 6B for bending and extending the arms are provided, and these switching valves 5A, 5B and 6A and 6B are sequentially switched by pilot pressure oil, and two hydraulic pumps 1 , 2 of pressure oil are merged, and a pair of boom cylinders 7
And one arm cylinder 8 is driven.

[Problems to be solved by the invention]

In the above case, the boom cylinder 7 and the arm cylinder 8
Is powerfully driven by two hydraulic pumps 1 and 2, so it is good for heavy excavation, but the intermediate excavation work that requires relatively little force after heavy excavation work and the operation of boom and arm cylinders 7 and 8 When adjusting the leveling work at a slower speed, the combined oil of the two hydraulic pumps 1 and 2 is used to adjust the switching stroke of the boom and arm switching valves 5A, 5B, 6A and 6B. Moreover, since the flow rate into the cylinder must be reduced, the operation is complicated and inconsistent, making it difficult for a novice operator to operate.

[Object of the Invention]

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a boom and an arm cylinder with two units.
By changing the delivery flow rate of the two hydraulic pumps, the force and speed of the boom and arm cylinders can be controlled, which simplifies the operation of the work machine and makes it easier for the novice operator to operate the hydraulic circuit device of the hydraulic excavator. To provide.

[Means for solving problems]

In order to achieve the above object, the present invention provides an arm low-speed switching valve 29 that is provided in the hydraulic circuit of one hydraulic pump 21 to extend and retract the arm cylinder 34 by a switching operation, and a hydraulic circuit of the other hydraulic pump 22. Boom low-speed switching valve 37 that is installed in
And a boom high speed increasing switching valve 25 provided in the hydraulic circuit of one hydraulic pump 21 to supply the discharge oil of the hydraulic pump 21 to the bottom side of the boom cylinder 40 by a switching operation, and the hydraulic circuit of the other hydraulic pump 22. And a boom high speed switching valve 25 and a boom low speed switching valve which are interlocked with the boom operation lever 65 and the arm high speed switching valve 42 which is provided on the arm pump 34 to supply the oil discharged from the hydraulic pump 22 to the arm cylinder 34. Boom operation PPC valve 54 for switching operation with 37, and arm high speed increase switching valve 42 and arm low speed switching valve 29 linked with arm operation lever 66.
Arm operation PPC valve 52 for performing switching operation between the boom high speed acceleration switching valve 25 and the boom operation mode switching valve 63 for opening and closing the switching pilot circuit provided in the switching pilot circuit of the boom high speed acceleration switching valve 25, and the arm high speed acceleration valve. An arm operation mode switching valve 60, which is provided in the switching pilot circuit of the switching valve 42 and opens and closes the switching pilot circuit, is provided.

[Action]

Without operating the boom operation mode switching valve 63 and the arm operation mode switching valve 60, operate the boom operation lever 65 to operate the boom operation PPC valve 54 to switch the boom high speed increase switching valve 25 and the boom low speed change valve 37. The hydraulic oil of one hydraulic pump 21 and the hydraulic oil of the other hydraulic pump 22 respectively.
It is supplied to the bottom side of 40 to extend the boom cylinder 40.

Then, by switching the boom operation mode switching valve 63, the pilot pressure to the boom high speed acceleration switching valve 25 is shut off,
The supply of oil from the boom high speed speed changeover valve 25 to the boom cylinder 40 is stopped, and the pressure oil is supplied to the boom cylinder 40 only from the other hydraulic poun 22. In addition, the arm operation lever 66 is operated to operate the arm operation PPC valve 52 to operate the arm high speed switching valve 42.
And the arm low speed switching valve 29 are switched to switch one of the pressure oil pumps 21
And the pressure oil of the other hydraulic pump 22 are supplied to the bottom side of the arm cylinder 34 to extend the arm cylinder 34.

Then, by switching the arm operation mode switching valve 60, the pilot pressure to the arm high speed acceleration switching valve 42 is shut off, and the oil supply from the arm high speed acceleration switching valve 42 to the arm cylinder 34 is stopped to the arm cylinder 34. The pressure oil is supplied only from one hydraulic pump 21.

〔Example〕

 An embodiment of the present invention will be described below with reference to FIG.

In the drawing, 20 is a fixed displacement pilot control pump, and 21 and 22 are variable displacement hydraulic pumps.

The discharge side of one hydraulic pump 21 is connected to the ports 25a and 25b of the boom high speed increase / reversal switching valve 25 via pipes 23 and 24,
A check valve 26 is provided in the pipe line 23. The port 25c of the boom high speed speed increase switching valve 25 communicates with the tank 27, and the port 25d is connected to the port 29a of the arm low speed switching valve 29 via the pipe line 28. Further, the discharge side of the hydraulic pump 21 is connected to the port 29b of the arm low speed switching valve 29 via the pipe line 30,
A check valve 31 is provided in this conduit 30. The ports 29c, 29d of the arm low speed switching valve 29 are connected to the arm cylinder 34 via the pipes 32, 33, and the port 29c, 29d of the arm low speed switching valve 29 is connected.
The e and 29f communicate with the tank 27.

The discharge side of the other hydraulic pump 22 is connected to the ports 37a and 37b of the boom low speed switching valve 37 via the pipes 35 and 36, and the pipe 35 is provided with a check valve 36 '. Boom low speed switching valve
Port 37c of 37 leads to tank 27, and ports 37d and 37e
Is connected to the boom cylinder 40 via lines 38, 39. Further, the port 37f of the boom low speed switching valve 37 is connected to the arm high speed increasing switching valve via a pipe line 41 and a pipe line 44 having a check valve 43.
It is connected to ports 42a and 42b of 42. Further, the discharge side of the hydraulic pump 22 is connected to a port 42b of the arm high speed speed up switching valve 42 via a pipe line 45. The ports 42c, 42d of the arm high speed speed changeover valve 42 are connected to the arm cylinder 34 via the pipes 46, 47, and the ports 42e, 42f of the arm high speed speed changeover valve 42 communicate with the tank 27.

Further, a check 48 is provided in the pipe line 47, and the port 25e of the boom high speed increase / reduction switching valve 25 is connected to the bottom side of the boom cylinder 40 via a pipe line 49. 50 is provided.

An arm operation PPC valve 52 is provided on one discharge line 51 of the pilot control pump 20, and a boom operation PPC valve 54 is provided on the other discharge line 53, and the discharge lines 51 and 53 communicate with an accumulator 55. There is.

The pilot port 52a of the arm operation PPC valve 52 is provided with a high speed / low speed switching valve 42 for the arm via pilot lines 56, 57.
It is connected to one of the 29 pilot ports 42g, 29g,
The pilot port 52b of the arm operation PPC valve 52 is connected to the other pilot ports 42i, 29i of the high speed / low speed switching valves 42, 29 via the pilot lines 58, 59, and the arm is connected to the pilot line 58. An operation mode switching valve 60 is provided.

In addition, the pilot port 54a of the boom operation PPC valve 54
Is connected to the pilot ports 25g and 37g of the boom high speed and low speed switching valves 25 and 37 via pilot lines 61 and 62,
A boom operation mode switching valve 63 is provided in the pilot conduit 61, and the pilot port 54b of the boom operating PPC valve 54 is connected to the pilot port 37i of the boom low speed switching valve 37 via the pilot conduit 64.

 Next, the operation will be described.

When the boom operation lever 65 is operated to the up side, the boom operation PPC valve 54 operates and pilot pressure rises in the pilot port 25g of the boom high speed increase switching valve 25 and the pilot port 37g of the boom low speed switching valve 37, respectively, and the boom height increases. Acceleration,
The low speed switching valves 25 and 37 are switched. For this reason, the oil discharged from the hydraulic pump 22 is supplied to the boom low-speed switching valve 37 and the pipeline.
The boom cylinder 40 is extended via 38 to enter the bottom side of the boom cylinder 40, and the oil discharged from the hydraulic pump 21 enters the bottom side of the boom cylinder 40 via the boom high speed increase / decrease switching valve 25 and the conduit 49. .

Further, by switching the boom operation mode switching valve 63, the pilot pressure to the pilot port 25g of the boom high speed increasing switching valve 25 is shut off, and the boom high speed increasing switching valve 25 is switched to the neutral position. Hydraulic pump 22
Only discharge the oil from.

When the boom operation lever 65 is operated to the lower side, the boom operation PPC valve 54 operates in the opposite direction to the above, and pilot pressure is established in the pilot port 37i of the boom low speed switching valve 37, and the boom low speed switching valve 37 is switched. The oil discharged from the hydraulic pump 22 flows to the rod side of the boom cylinder 40, and the boom cylinder 40 contracts.

When the arm operation lever 66 is operated to the up side, the arm operation PPC valve 52 is actuated, and pilot pressure rises in the pilot port 42i of the arm high speed increase switching valve 42 and the pilot port 29i of the arm low speed switching valve 29, respectively, and the arm high Acceleration,
The low speed switching valves 42 and 29 are switched respectively. For this reason, the oil discharged from the hydraulic pump 21 is supplied to the arm low-speed switching valve 29 and the pipeline.
Since the oil discharged from the hydraulic pump 22 enters the bottom side of the arm cylinder 34 via 32 and the arm high speed increase switching valve 42 and the conduit 46, the arm cylinder 34 increases its speed. Is stretched.

Further, by switching the arm operation mode switching valve 60, the pilot pressure to the pilot port 42i of the arm high speed increasing switching valve 42 is shut off, and the arm high speed increasing switching valve 42 is switched to the neutral position. Hydraulic pump 21
Only discharge the oil from.

When the arm operation lever 66 is operated to the lower side, the arm operation PPC valve 52 operates in the opposite direction to the above to increase the arm high speed,
Pilot pressure rises in the pilot ports 29g, 42g of the low speed switching valves 42, 27, the arm high speed increase, the low speed switching valves 42, 27 are switched, and the oil discharged from the hydraulic pump 21 flows to the rod side of the arm cylinder 34. This arm cylinder 34 shrinks.

〔The invention's effect〕

As described in detail above, the hydraulic circuit device of the hydraulic excavator according to the present invention is provided in the hydraulic circuit of the one hydraulic pump 21, and the arm low speed switching valve 29 for performing the expansion and contraction operation of the arm cylinder 34 by the switching operation, The boom low-speed switching valve 37 provided in the hydraulic circuit of the other hydraulic pump 22 for expanding and contracting the boom cylinder 40 by switching operation, and the discharge of the hydraulic pump 21 by switching operation provided in the hydraulic circuit of one hydraulic pump 21. The boom height increasing switching valve 25 for supplying oil to the potom side of the boom cylinder 40 and the arm height for supplying the discharge oil of the hydraulic pump 22 to the arm cylinder 34 by the switching operation provided in the hydraulic circuit of the other hydraulic pump 22. Boom operation PPC valve 54 for performing the switching operation between the boom high speed increase switching valve 25 and the boom low speed switching valve 37 by interlocking with the speed increasing switching valve 42 and the boom operation lever 65.
And an arm operation PPC valve 52 for switching between the arm high speed increase switching valve 42 and the arm low speed changeover valve 29 in conjunction with the arm operation lever 66, and a switching pilot circuit for the boom high speed increasing changeover valve 25. A boom operation mode switching valve 63 that is provided to open and close the switching pilot circuit, and an arm operation mode switching valve 60 that is provided to the switching pilot circuit of the arm high speed increase switching valve 42 to open and close the switching pilot circuit. It is characterized by having.

Therefore, without operating the boom operation mode switching valve 63 and the arm operation mode switching valve 60, the boom operation lever 65 is operated to operate the boom operation PPC valve 54 to operate the boom high speed increase switching valve 25 and the boom low speed change valve 37. The hydraulic oil of one hydraulic pump 21 and the hydraulic oil of the other hydraulic pump 22 are supplied to the bottom side of the boom cylinder 40, respectively.
To extend.

Then, by switching the boom operation mode switching valve 63, the pilot pressure to the boom high speed acceleration switching valve 25 is shut off,
The supply of oil from the boom high speed acceleration switching valve 25 to the boom cylinder 40 is stopped, and the pressure oil is supplied to the boom cylinder 40 only from the other hydraulic pump 22. In addition, the arm operation lever 66 is operated to operate the arm operation PPC valve 52 to operate the arm high speed switching valve 42.
And the arm low speed switching valve 29 are switched to switch one hydraulic pump 21.
And the pressure oil of the other hydraulic pump 22 are supplied to the bottom side of the arm cylinder 34 to extend the arm cylinder 34.

Then, by switching the arm operation mode switching valve 60, the pilot pressure to the arm high speed acceleration switching valve 42 is shut off,
The supply of oil from the arm high speed speed changeover valve 42 to the arm cylinder 34 is stopped, and the pressure oil is supplied to the arm cylinder 34 only from one hydraulic pump 21.

In this way, the boom high speed switching valve 25 and the boom low speed switching valve 37 are simultaneously switched to supply the discharge oil of the two hydraulic pumps 21 and 22 to the boom cylinder 40, and only the boom low speed switching valve 37 is selectively operated. Can be switched to supply the discharge pressure oil of one hydraulic pump 22 to the boom cylinder 40, and the arm high speed speed increasing switching valve 42 and the arm low speed switching valve 29 can be simultaneously switched to operate two hydraulic pumps. The 21, 22 discharge pressure oil is supplied to the arm cylinder 34, and the arm low-speed switching valve 29 is selectively
It is possible to supply only the pressure oil discharged from one hydraulic pump 21 to the arm cylinder 34 by switching only the hydraulic pump 21, and by changing the delivery flow rate of the hydraulic pumps 21 and 22 to the boom and arm cylinders 40 and 34, the boom, The force and speed of the arm cylinders 40, 34 can be controlled.

This simplifies the operation of the work implement and makes it easier for the novice operator to operate.

[Brief description of drawings]

FIG. 1 is a structural explanatory view of an embodiment of the present invention, FIG. 2 is a structural explanatory view of an arm cylinder operating circuit in a hydraulic circuit device of a conventional hydraulic excavating work machine, and FIG. 3 is a structural explanatory view of the boom operating circuit. It is a figure. 21,22 is a hydraulic pump, 25 is a boom high speed switching valve, 29 is an arm low speed switching valve, 37 is a boom high speed switching valve, 42 is an arm high speed switching valve, 52 is an arm operation PPC valve, 54 is Boom operation P
PC valve, 60 is arm operation mode switching valve, 63 is boom operation mode switching valve.

Claims (1)

[Claims] 1. An arm low-speed switching valve 29 which is provided in a hydraulic circuit of one hydraulic pump 21 to perform an extension / contraction operation of an arm cylinder 34 by a switching operation, and a hydraulic circuit of the other hydraulic pump 22 which is provided with a switching operation. A boom low speed switching valve 37 for expanding and contracting the boom cylinder 40 and a boom high speed increasing valve which is provided in the hydraulic circuit of one hydraulic pump 21 and supplies the discharge oil of the hydraulic pump 21 to the bottom side of the boom cylinder 40 by the switching operation. In conjunction with the switching valve 25, the arm high speed increase switching valve 42 provided in the hydraulic circuit of the other hydraulic pump 22 to supply the discharge oil of the hydraulic pump 22 to the arm cylinder 34 by the switching operation, and the boom operation lever 65. Boom operation PPC valve 54 for performing switching operation between the boom high speed increase switching valve 25 and the boom low speed switching valve 37
And an arm operation PPC valve 52 for switching between the arm high speed increase switching valve 42 and the arm low speed changeover valve 29 in conjunction with the arm operation lever 66, and a switching pilot circuit for the boom high speed increasing changeover valve 25. A boom operation mode switching valve 63 that is provided to open and close the switching pilot circuit, and an arm operation mode switching valve 60 that is provided to the switching pilot circuit of the arm high speed increase switching valve 42 to open and close the switching pilot circuit. A hydraulic circuit device for a hydraulic excavating work machine, comprising: