JP3253484B2 - Hydraulic circuit - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydraulic circuit for operating a working device of an industrial vehicle, for example, a boom and a bucket of a wheel loader.

[0002]

2. Description of the Related Art Conventionally, hydraulic circuits for operating a boom and a bucket of a wheel loader, which is an example of a working device of an industrial vehicle, include those shown in FIGS. 5 and 6, for example. That is, 51 is a bucket hydraulic cylinder that operates the bucket, and 52 is a boom hydraulic cylinder that operates the boom. The vehicle body is provided with two pumps 54 and 55 for supplying pressure oil from the oil tank 53 to the bucket hydraulic cylinder 51 and the boom hydraulic cylinder 52. The discharge side of one pump 54 and the discharge side of the other pump 55 are combined into one pipe 56, and the flow of pressure oil flows downstream of this pipe 56 through the hydraulic cylinder 52 for the boom.
And a main valve 57 for switching between the side of the hydraulic cylinder 51 and the side of the hydraulic cylinder 51 for the bucket. Above main valve
Reference numeral 57 denotes a 6-port 3-position switching valve 58 connected to the bucket hydraulic cylinder 51, and a 6-port 4-position switching valve 59 connected downstream of the switching valve 58 and connected to the boom hydraulic cylinder 52. It is composed of Further, a pipe 60 for connecting the discharge side of the other pump 55 and the main valve 57 is provided.
Is provided with a steering valve 61 in the middle.

According to this, when the bucket is turned upward, one of the switching valves 58 of the main valve 57 is moved to the neutral position A2.
To the switching position A1. As a result, the pressure oil flows from the pumps 54 and 55 through the pipe 56 into the switching valve 58, is switched at the switching position A1, flows through the pipe 65, and is supplied to the extension-side working chamber 62 of the bucket hydraulic cylinder 51. Is done. As a result, the piston rod 63 of the bucket hydraulic cylinder 51 is extended, and the bucket operates upward.
At this time, the oil in the shortened side working chamber 64 of the bucket hydraulic cylinder 51 flows into the switching valve 58 through the pipe 66, is switched at the switching position A1, passes from the pipe 67, passes through the pipe 68, and further passes through the pipe 69. Collected in the oil tank 53.

When the bucket is to be turned downward, the switching valve 58 of the main valve 57 is switched to the switching position A3,
The piston rod 63 of the bucket hydraulic cylinder 51 may be shortened.

In order to lift the bucket by rotating the boom upward, one switching valve 58 of the main valve 57 is used.
Is switched to the neutral position A2, the other switching valve 59 is switched from the neutral position B2 to the switching position B1. As a result, the pressure oil flows from the two pumps 54 and 55 through the pipe 56, passes through the switching valve 58 at the neutral position A2, flows into the other switching valve 59, is switched at the switching position B1, and passes through the pipe 73 and both booms. Is supplied to the extension side working chamber 70 of the hydraulic cylinder 52 for use. As a result, the piston rod of the hydraulic cylinder 52 for both booms
Each 71 extends and the boom pivots upward. At this time, the oil in the shortened side working chamber 72 of both boom hydraulic cylinders 52 flows into the switching valve 59 through the pipe 74, respectively.
The oil is switched at the switching position B1 and is recovered from the pipe 75 through the pipe 76 to the oil tank 53 via the pipe 69.

When lowering the bucket by rotating the boom downward, the switching valve 59 of the main valve 57 is switched to the neutral position A2 while the other switching valve 59 is switched to the switching position B3. The piston rods 71 of both boom hydraulic cylinders 52 may be shortened.

[0007]

However, in the above-described conventional type, since one main valve 57 is provided for two pumps 54 and 55, the boom hydraulic cylinder 52 is provided.
And the bucket hydraulic cylinder 51 cannot be operated at the same time, so that the boom and the bucket could not be operated at the same time. When only the boom is operated, the boom cannot be operated at a higher speed than usual.

An object of the present invention is to solve the above-mentioned problem, and an object of the present invention is to provide a hydraulic circuit capable of simultaneously operating a plurality of hydraulic cylinders for operating a working device (boom, bucket, etc.).

[0009]

SUMMARY OF THE INVENTION In order to solve the above problems, a hydraulic circuit according to the present invention is provided for an industrial vehicle, comprising: a bucket hydraulic cylinder for operating a bucket; a boom hydraulic cylinder for operating a boom; A first main pump for supplying pressure oil to the hydraulic cylinder for boom, and a second main pump for supplying pressure oil to the boom hydraulic cylinder for switching the flow of pressure oil supplied from the first main pump. The first main valve and the second main valve
A second main valve for switching a flow of the pressure oil supplied from the main pump; and a first main valve for supplying the pressure oil supplied from the first main pump to one of a bucket hydraulic cylinder and a boom hydraulic cylinder. The second main valve supplies pressure oil supplied from the second main pump to the boom hydraulic cylinder, and switches the first main valve to supply pressure oil to the boom. Supply to the hydraulic cylinder and the second
When the main valve is switched to supply the pressure oil to the hydraulic cylinder for the boom, the pressure oil discharged from the first main pump is supplied to the hydraulic cylinder for the boom through one pipe through the first main valve. The pressure oil discharged from the second main pump is supplied to the boom hydraulic cylinder through the second main valve, and is supplied to the boom hydraulic cylinder through the other pipe which joins the one pipe, and is simultaneously discharged from the boom hydraulic cylinder. The pressure oil is recovered through a first main valve through a specific pipe, and is recovered through a second main valve through another pipe branched from the specific pipe.

[0010]

According to the structure of the present invention, the first main pump is driven to supply the pressure oil to the bucket hydraulic cylinder, and the second main pump is driven to supply the pressure oil to the boom hydraulic cylinder. At this time, the flow of the pressure oil supplied from the first main pump is switched using the first main valve, and the flow of the pressure oil supplied from the second main pump is switched using the second main valve. , The bucket and the boom can be operated simultaneously.

Further , the first main valve is switched to switch the first main valve.
Supplying pressure oil supplied from the main pump to the boom hydraulic cylinder, and supplying pressure oil supplied from the second main pump to the boom hydraulic cylinder by the second main valve, thereby supplying the boom hydraulic cylinder hydraulic oil amount of the Ri Do in a combination of the supply from the supply amount and the second main pump from the first main pump,
The pressure discharged from the boom hydraulic cylinder correspondingly
The amount of power oil flows through one pipe and the other flows through another pipe
Emissions are combined. Therefore, for the boom
The amount of pressure oil supplied to the hydraulic cylinder and the hydraulic
Since both the amount of pressure oil discharged from the bender and the amount of pressure oil discharged from the boom can be made higher than usual, it becomes possible to operate the boom faster than usual.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to FIGS. As shown in FIG. 3, reference numeral 1 denotes a wheel loader, which is an example of an industrial vehicle, provided with a bucket 2 and a boom 3, which are examples of a working device. The bucket 2 is actuated by a bucket hydraulic cylinder 4, and the boom 3 is actuated by a pair of left and right boom hydraulic cylinders 5.

As shown in FIGS. 1 and 2, a vehicle main body of the wheel loader 1 has a first main pump 8 for supplying oil in an oil tank 7 to a hydraulic cylinder 4 for a bucket, and an oil in the oil tank 7. And a second main pump 9 that supplies the hydraulic pressure to the boom hydraulic cylinder 5. These main pumps 8 and 9 are driven by the engine 6. The first
A first main valve for switching the flow of the pressure oil supplied from the first main pump 8 is provided on the discharge side of the main pump 8.
Ten are provided. On the discharge side of the second main pump 9, a second main valve 11 for switching the flow of the pressure oil supplied from the second main pump 9 is provided.

The first main valve 10 is a 6-port 3-position switching valve 12 connected to the bucket hydraulic cylinder 4.
And a 6-port 4-position switching valve 13 connected to the downstream side of the switching valve 12 and connected to the boom hydraulic cylinder 5. The second main valve 11 is constituted by a 6-port 4-position switching valve 14 connected to the boom hydraulic cylinder 5. Each switching valve 12, 13, 14
Is switched by an operation lever (not shown) provided in the driver's seat.

The operation of the above configuration will be described below.
When the bucket 2 is turned upward, the switching valve 12 of the first main valve 10 is switched from the neutral position A2 to the switching position A1 by operating the operation lever. As a result, the pressure oil flows from the first main pump 8 through the pipe 16 into the switching valve 12 and is switched at the switching position A1 to switch the pipe 17
And supplied to the extension side working chamber 18 of the bucket hydraulic cylinder 4. Thereby, the piston rod 19 of the bucket hydraulic cylinder 4 is extended, and the bucket 2 operates upward. At this time, the oil in the shortened side working chamber 20 of the bucket hydraulic cylinder 4 flows into the switching valve 12 through the pipe 21, is switched at the switching position A 1, passes from the pipe 22 through the pipe 23, and further through the pipe 24. Collected in the oil tank 7.

When the bucket 2 is turned downward,
The switching valve 12 of the first main valve 10 is switched to the switching position A3 to shorten the piston rod 19 of the bucket hydraulic cylinder 4.

When the bucket 2 is lifted by rotating the boom 3 upward at a normal speed, one of the switching valves 12 of the first main valve 10 is operated by operating the operation lever.
Is switched to the neutral position A2, the other switching valve 13 is switched from the neutral position B2 to the switching position B1. Thereby, the pressure oil passes from the first main pump 8 through the pipe 16,
After passing through the switching valve 12 at the neutral position A2, it flows into the switching valve 13, is switched at the switching position B1, and is supplied to the extension side working chamber 26 of the hydraulic cylinders 5 for both booms through the pipe 25. Thereby, the piston rod of the hydraulic cylinder 5 for both booms
27 extend, and the boom 3 rotates upward at a normal speed. At this time, the oil in the shortened side working chamber 28 of both the boom hydraulic cylinders 5 passes through the pipe 29 and passes through the switching valve 13
And is switched at the switching position B1 to be recovered from the pipe 30 through the pipe 31 and further through the pipe 24 to the oil tank 7.

When lowering the bucket 2 by rotating the boom 3 downward at a normal speed, the first main valve 10
In the state where one of the switching valves 12 is switched to the neutral position A2, the other switching valve 13 is switched to the switching position B3, and the piston rods 27 of both the boom hydraulic cylinders 5 may be shortened. Further, by switching the other switching valve 13 to the switching position B4, it is possible to make the vertical rotation of the boom 3 free.

When the bucket 2 is turned upward and the boom 3 is turned upward to lift the bucket 2 at the same time, the operating lever is operated to switch the switching valve 12 of the first main valve 10. From the neutral position A2 to the switching position A1, and the second main valve
The eleventh switching valve 14 is switched from the neutral position C2 to the switching position C1.

As a result, the pressure oil discharged from the first main pump 8 passes through the pipe 16 and passes through the first main valve 10.
Of the bucket hydraulic cylinder 4, the piston rod 19 of the bucket hydraulic cylinder 4 extends, and the bucket 2 is moved. Operates upward. At the same time, the pressure oil discharged from the second main pump 9 passes through the pipe 32 and passes through the switching valve 14 of the second main valve 11.
And is switched at the switching position C1, flows through the pipe 33, and is supplied to the extension side working chambers 26 of the hydraulic cylinders 5 for both booms, respectively. Rotate upward.

At this time, the oil in the shortening side working chamber 20 of the bucket hydraulic cylinder 4 flows into the switching valve 12 through the pipe 21 and is switched at the switching position A1 to be switched from the pipe 22 to the piping.
The oil is collected in the oil tank 7 through the pipe 23 and the pipe 24. In addition, the shortened working chamber 28 of the hydraulic cylinder 5 for both booms is used.
Each of the oils inside flows into the switching valve 14 through the pipe 34, and is switched at the switching position C1, and
And is collected in the oil tank 7 via the pipe 37.

Similarly, when simultaneously turning the bucket 2 upward and lowering the bucket 2 by rotating the boom 3 downward, the switching valve 12 of the first main valve 10 is switched to the switching position A1. , Second main valve 11
The switching valve 14 may be switched to the switching position C3. Also,
When the bucket 2 is turned downward and the boom 3 is rotated upward to lift the bucket 2 at the same time, the switching valve 12 of the first main valve 10 is switched to the switching position A3, and the second main valve 11 is switched. The switching valve 14 may be switched to the switching position C1. Further, when simultaneously turning the bucket 2 downward and lowering the bucket 2 by rotating the boom 3 downward, the switching valve 12 of the first main valve 10 is switched to the switching position A3,
The switching valve 14 of the second main valve 11 may be switched to the switching position C3. When the bucket 2 is turned upward and the boom 3 is turned up and down freely, the switching valve 12 of the first main valve 10 is switched to the switching position A.
1 and the switching valve of the second main valve 11
14 may be switched to the switching position C4. Further, when the bucket 2 is turned downward and the boom 3 is turned up and down freely, the switching valve 12 of the first main valve 10 is switched to the switching position A3.
The switching valve 14 of the second main valve 11 may be switched to the switching position C4.

As described above, the operation of the bucket 2 and the boom 3
In addition to performing the operations separately, the operation of the bucket 2 and the operation of the boom 3 can be performed simultaneously, so that excavation work and the like can be performed quickly. At this time, the operating speed of the bucket 2 and the operating speed of the boom 3 can be adjusted by adjusting the respective discharge rates of the first main pump 8 and the second main pump 9.

In the above embodiment, as shown in FIG.
By adjusting the urging force of the spring 38 of the switching valve 14 of the second main valve 11, the switching operation of the switching valve 14
It is also possible to delay the switching operation of the switching valve 12 of the main valve 10.

Further, when the boom 3 is rotated upward at a higher speed than usual, one of the switching valves 12 of the first main valve 10 is switched to the neutral position A2 and the other switching valve 13 is switched to the neutral position A2.
Is switched to the switching position B1, and the switching valve 14 of the second main valve 11 is switched to the switching position C1.

As a result, the pressure oil discharged from the first main pump 8 passes through the pipe 16, passes through the switching valve at the neutral position A2.
After passing through 12, it flows into the switching valve 13, is switched at the switching position B1, and is supplied to the extension side working chamber 26 of both boom hydraulic cylinders 5 through the pipe 25 (corresponding to one of the pipes) . At the same time, the pressure oil discharged from the second main pump 9
It flows into the switching valve 14 of the second main valve 11 through the pipe 32, and is switched at the switching position C1 so that the pipe 33 (the other
(Corresponding to a pipe) , and are supplied to the extension side working chambers 26 of both the boom hydraulic cylinders 5.

At this time, oil in the working chamber 28 on the shortening side of the hydraulic cylinders 5 for both booms is supplied to a pipe 29 (a specific pipe,
At the switching position B1 and is recovered from the pipe 30 through the pipe 31 to the oil tank 7 via the pipe 24 at the same time as the pipe 34 (separately).
Flows into the switching valve 14 through the corresponding to the pipe), it is switched by the switching positions C1 through the street further pipe 37 a pipe 36 from the pipe 35 is collected in the oil tank 7.

As described above, both boom hydraulic cylinders 5
The amount of pressurized oil supplied to the extension side working chamber 26 is the sum of the amount of supply from the first main pump 8 and the amount of supply from the second main pump 9. The amount of pressure oil discharged from the shortening side working chamber 28 of the hydraulic cylinder 5 is also the sum of the amount of discharge flowing through the pipe 29 and the amount of discharge flowing through the pipe 34. Therefore, the extension side working chamber 26
The amount of pressure oil supplied to the boom and the amount of pressure oil discharged from the shortening side working chamber 28 can both be increased more than usual, so that the piston rods 27 of both the boom hydraulic cylinders 5 extend at a high speed, 3 can be rotated upward at a higher speed than usual. When the boom 3 is rotated downward at a higher speed than usual, the one switching valve 12 of the first main valve 10 is switched to the neutral position A2 while the other switching valve 13 is switched to the switching position B3. , Second
The switching valve 14 of the main valve 11 may be switched to the switching position C3.

In the above embodiment, the first main valve 10 is provided on the discharge side of the first main pump 8 and the second main valve 11 is provided on the discharge side of the second main pump 9. However, as another embodiment, As shown in FIG. 4, the third main pump 41 may be added, and the second main valve 11 may be provided on the discharge side of the second main pump 9 and the third main pump 41.

[0030]

As described above, according to the present invention , the first main pump is driven to supply the pressure oil to the bucket hydraulic cylinder, and the second main pump is driven to supply the pressure oil to the boom hydraulic cylinder. In this case, the flow of the pressure oil supplied from the first main pump is switched using the first main valve, and the flow of the pressure oil supplied from the second main pump is switched using the second main valve. , The bucket and the boom can be operated simultaneously. Therefore, excavation work and the like can be performed quickly.

Further , by switching the first main valve, the first
Supplying pressure oil supplied from the main pump to the boom hydraulic cylinder, and supplying pressure oil supplied from the second main pump to the boom hydraulic cylinder by the second main valve, thereby supplying the boom hydraulic cylinder hydraulic oil amount of the Ri Do in a combination of the supply from the supply amount and the second main pump from the first main pump,
The pressure discharged from the boom hydraulic cylinder correspondingly
The amount of power oil flows through one pipe and the other flows through another pipe
Emissions are combined. Therefore, for the boom
The amount of pressure oil supplied to the hydraulic cylinder and the hydraulic
Since both the amount of pressure oil discharged from the cylinder and the amount of pressure oil discharged from the boom can be made higher than usual, it becomes possible to operate the boom faster than usual.

[Brief description of the drawings]

FIG. 1 is a hydraulic circuit diagram according to an embodiment of the present invention.

FIG. 2 is an enlarged view of a main part of the hydraulic circuit in FIG.

FIG. 3 is a side view of a wheel loader provided with the hydraulic circuit.

FIG. 4 is a hydraulic circuit diagram in another embodiment of the present invention.

FIG. 5 is a hydraulic circuit diagram in a conventional example.

FIG. 6 is an enlarged view of a main part of the hydraulic circuit in FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Wheel loader (industrial vehicle) 2 Bucket (working device) 3 Boom (working device) 4 Bucket hydraulic cylinder 5 Boom hydraulic cylinder 8 First main pump 9 Second main pump 10 First main valve 11 Second main valve

──────────────────────────────────────────────────続 き Continuation of front page (58) Field surveyed (Int.Cl. ⁷ , DB name) E02F 9/22 E02F 3/43

Claims (1)

(57) [Claims] 1. A hydraulic cylinder for a bucket that operates a bucket, a hydraulic cylinder for a boom that operates a boom, a first main pump that supplies pressure oil to the hydraulic cylinder for a bucket, and a boom for the boom. A second main pump that supplies pressure oil to the hydraulic cylinder; a first main valve that switches a flow of pressure oil supplied from the first main pump; and a flow of pressure oil supplied from the second main pump A first main valve for selectively switching and supplying the hydraulic oil supplied from the first main pump to one of the bucket hydraulic cylinder and the boom hydraulic cylinder. The second main valve supplies the pressure oil supplied from the second main pump to the boom hydraulic cylinder. When the in-valve is switched to supply the pressure oil to the boom hydraulic cylinder and the second main valve is switched to supply the pressure oil to the boom hydraulic cylinder, the pressure oil discharged from the first main pump is supplied to the first main valve. if a is supplied to the boom hydraulic cylinder through one of the pipes through, to the second pressure fluid discharged from the main pump through the second main valve of one said pipe
The pressure oil supplied to the boom hydraulic cylinder through the other flowing pipe, and simultaneously discharged from the boom hydraulic cylinder, is recovered through the first main valve through the specific pipe, and A hydraulic circuit, wherein the hydraulic circuit is recovered through a second main valve through another pipe branched from the pipe.