JPH08291540A - Hydraulic circuit - Google Patents

Abstract

PURPOSE: To simultaneously actuate hydraulic cylinders by arranging main pumps to supply pressure oil to plural hydraulic cylinders, and arranging main valves to switch a flow of pressure oil supplied from these respective main pumps with every kind of respective hydraulic cylinders. CONSTITUTION: Pressure oil is supplied to a hydraulic cylinder 4 for a bucket by driving a first main pump 8. At the same time, pressure oil is supplied to a hydraulic cylinder 5 for a boom by driving a second main pump 9. In that case, a flow of the pressure oil from the pump 8 is switched by using a valve 10, and a flow of the pressure oil from the pump 9 is switched by using a valve 11. Then, the bucket and the boom are simultaneously actuated. The valve 10 is switched, and when the pressure oil from the pump 8 is supplied to the cylinder 5 and the pressure oil from the pump 9 is supplied to the cylinder 5 by the valve 11, the pressure oil is increased more than usual, and the boom is actuated at high speed. Therefore, excavating work or the like can be quickly performed.

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, such as a boom and a bucket of a wheel loader.

[0002]

2. Description of the Related Art Conventional hydraulic circuits for operating a boom and a bucket of a wheel loader, which is an example of a working device for an industrial vehicle, include those shown in FIGS. That is, 51 is a bucket hydraulic cylinder that operates a bucket, and 52 is a boom hydraulic cylinder that operates a boom. The vehicle body is provided with two pumps 54, 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 integrated into one pipe 56, and the flow of pressure oil is provided on the downstream side of this pipe 56 with the boom hydraulic cylinder 52.
There is provided one main valve 57 for switching between the side of and the side of the bucket hydraulic cylinder 51. Main valve above
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 consists of and. In addition, a pipe 60 that connects the discharge side of the other pump 55 and the main valve 57.
A steering valve 61 is provided midway.

According to this, when the bucket is turned upward, one switching valve 58 of the main valve 57 is set to the neutral position A2.
To the switching position A1. As a result, the pressure oil flows from both pumps 54, 55 into the switching valve 58 through the pipe 56, is switched at the switching position A1 and flows through the pipe 65, and is supplied to the extension side working chamber 62 of the bucket hydraulic cylinder 51. To be done. As a result, the piston rod 63 of the bucket hydraulic cylinder 51 extends and the bucket operates upward.
At this time, the oil in the shortening 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 to the pipe 68, and further to the pipe 69. It is collected in the oil tank 53.

When the bucket is 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.

When the boom is rotated upward to lift the bucket, one switching valve 58 of the main valve 57 is used.
The other switching valve 59 is switched from the neutral position B2 to the switching position B1 in the state where the switch position is switched to the neutral position A2. As a result, the pressure oil passes from both pumps 54 and 55 through the pipe 56, passes through the switching valve 58 at the neutral position A2 and flows into the other switching valve 59, and is switched at the switching position B1 to pass through the pipe 73 and both booms. Is supplied to the extension side working chamber 70 of the hydraulic cylinder 52 for use. This allows the piston rod of the hydraulic cylinder 52 for both booms to
71 extends and the boom rotates upward. At this time, the oil in the shortening side working chamber 72 of both boom hydraulic cylinders 52 respectively flows into the switching valve 59 through the pipe 74,
The oil is collected in the oil tank 53 after being switched at the switching position B1 through the pipe 75, the pipe 76 and the pipe 69.

When the boom is rotated downward to lower the bucket, one switching valve 58 of the main valve 57 is switched to the neutral position A2 and 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-mentioned conventional type, since one main valve 57 is provided for two pumps 54, 55, the boom hydraulic cylinder 52 is not provided.
And the bucket hydraulic cylinder 51 could not be operated at the same time, and therefore the boom and the bucket could not be operated at the same time. Also, when operating only the boom, it was not possible to operate this boom faster than usual.

The present invention solves the above problems, and an object thereof is to provide a hydraulic circuit capable of simultaneously operating a plurality of hydraulic cylinders for operating a work device (boom, bucket, etc.).

[0009]

In order to solve the above problems, a hydraulic circuit according to the first aspect of the present invention includes an industrial vehicle including a main pump for supplying pressure oil to a plurality of hydraulic cylinders for operating a plurality of working devices. A plurality of main valves are provided for switching the flow of the pressure oil supplied from each of the main pumps, for each type of the hydraulic cylinders.

In the hydraulic circuit according to the second aspect of the present invention, the industrial vehicle is a wheel loader, the working device is a bucket and a boom, and the hydraulic cylinders are a bucket hydraulic cylinder for operating the bucket and a boom hydraulic cylinder for operating the boom, respectively. A hydraulic cylinder, a main pump serving as a first main pump that supplies pressure oil to the bucket hydraulic cylinder, and a second main pump that supplies pressure oil to the boom hydraulic cylinder, respectively, and main valves respectively serving as the first main pump and the first main pump. A first main valve for switching the flow of pressure oil supplied from the main pump and a second main valve for switching the flow of pressure oil supplied from the second main pump.

Further, the hydraulic circuit according to the third aspect of the present invention is
The first main valve selectively supplies the pressure oil supplied from the first main pump to either the bucket hydraulic cylinder or the boom hydraulic cylinder, and the second main valve supplies the hydraulic oil from the second main pump. The pressure oil is supplied to the boom hydraulic cylinder.

[0012]

According to the structure of the first invention, when only one working device is operated, one main pump is driven to supply pressure oil to one hydraulic cylinder and one main valve is used. Then, the flow of the pressure oil supplied to the one hydraulic cylinder may be switched.

Further, by driving the plurality of main pumps to supply the pressure oil to the plurality of hydraulic cylinders and switching the flow of the pressure oil supplied to the plurality of hydraulic cylinders by using the plurality of main valves. , Multiple working devices can be operated simultaneously.

According to the second aspect 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 pressure oil supplied from the first main pump is switched using the first main valve, and the flow of pressure oil supplied from the second main pump is switched using the second main valve. Thus, the bucket and the boom can be operated at the same time.

According to the third aspect of the present invention, the pressure oil supplied from the first main pump is switched to the hydraulic cylinder for boom and the pressure oil supplied from the second main pump is switched. Is supplied to the boom hydraulic cylinder by the second main valve,
The amount of pressure oil supplied to the boom hydraulic cylinder is the sum of the amount supplied from the first main pump and the amount supplied from the second main pump. As described above, the amount of pressure oil supplied to the boom hydraulic cylinder can be increased more than usual, so that the boom can be operated faster than usual.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An 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, and is provided with a bucket 2 and a boom 3 which are an example of a working device. The bucket 2 is operated by a bucket hydraulic cylinder 4, and the boom 3 is operated by a pair of left and right boom hydraulic cylinders 5.

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

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 downstream of the switching valve 12 and connected to the boom hydraulic cylinder 5. The second main valve 11 is composed of a 6-port 4-position switching valve 14 connected to the boom hydraulic cylinder 5. Each of the above switching valves 12, 13, 14
Can be switched by an operating lever (not shown) provided in the driver's seat.

The operation of the above structure will be described below.
When the bucket 2 is turned upward, the switching lever 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 so that the piping 17
And is supplied to the extension side working chamber 18 of the bucket hydraulic cylinder 4. As a result, the piston rod 19 of the bucket hydraulic cylinder 4 extends and the bucket 2 operates 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, is switched at the switching position A1, passes from the pipe 22 to the pipe 23, and further via the pipe 24. It is collected in the oil tank 7.

When the bucket 2 is turned downward,
The switching valve 12 of the first main valve 10 may be 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. As a result, 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 and flowing into the switching valve 13, it is switched at the switching position B1 and supplied to the extension side working chamber 26 of the boom hydraulic cylinders 5 through the pipe 25. As a result, the piston rod of the hydraulic cylinder 5 for both booms is
27 extends and the boom 3 rotates upward at a normal speed. At this time, the oil in the shortening side working chambers 28 of the hydraulic cylinders 5 for both booms passes through the pipes 29, respectively, and the switching valve 13
Is collected in the oil tank 7 through the pipe 30, the pipe 31 and the pipe 24.

When the boom 3 is rotated downward at a normal speed to lower the bucket 2, the first main valve 10
One switching valve 12 may be switched to the neutral position A2, and the other switching valve 13 may be switched to the switching position B3 to shorten the piston rods 27 of both boom hydraulic cylinders 5. Further, by switching the other switching valve 13 to the switching position B4, the boom 3 can be freely rotated up and down.

When the bucket 2 is turned upward and the boom 3 is rotated upward to lift the bucket 2, at the same time, the switching lever 12 of the first main valve 10 is operated by operating the operation lever. Is switched from the neutral position A2 to the switching position A1, and the second main valve
The switching valve 14 of 11 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 the first main valve 10 described above.
Of the bucket hydraulic cylinder 4 is supplied to the extension side working chamber 18 of the bucket hydraulic cylinder 4 and the piston rod 19 of the bucket hydraulic cylinder 4 is extended to form the bucket 2 Operates upward. At the same time, the pressure oil discharged from the second main pump 9 passes through the pipe 32 and the switching valve 14 of the second main valve 11 described above.
To the extension side working chambers 26 of the boom hydraulic cylinders 5, and the piston rods 27 of the boom hydraulic cylinders 5 are extended to move the boom 3 to the boom 3. Rotate upwards.

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, is switched at the switching position A1, and is switched from the pipe 22 to the pipe.
It is collected in the oil tank 7 through 23 and further through the pipe 24. Also, the shortening side working chamber 28 of the hydraulic cylinders 5 for both booms is
The oil in each flows into the switching valve 14 through the pipe 34 and is switched at the switching position C1 so that the oil flows from the pipe 35 to the pipe 36.
The oil is collected in the oil tank 7 through the pipe 37.

Similarly, when the bucket 2 is turned upward and the boom 2 is turned downward to lower the bucket 2, the switching valve 12 of the first main valve 10 is switched to the switching position A1. , Second main valve 11
It suffices to switch the switching valve 14 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 moved. It suffices to switch the switching valve 14 to the switching position C1. Further, when the bucket 2 is turned downward and the boom 2 is turned downward to lower 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 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 at the same time, the switching valve 12 of the first main valve 10 is set to the switching position A.
Switch to 1 and switch valve of the second main valve 11
14 may be switched to the switching position C4. Further, when the downward movement of the bucket 2 and the free rotation of the boom 3 are simultaneously performed, the switching valve 12 of the first main valve 10 is switched to the switching position A3, and
The switching valve 14 of the second main valve 11 may be switched to the switching position C4.

Thus, the operation of the bucket 2 and the boom 3
The operation of the bucket 2 and the operation of the boom 3 can be performed at the same time, and thus 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 discharge amounts of the first main pump 8 and the second main pump 9, respectively.

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

Further, when the boom 3 is rotated upward at a higher speed than usual, one switching valve 12 of the first main valve 10 is switched to the neutral position A2 and the other switching valve 13 is switched.
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 and 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. At the same time, the pressure oil discharged from the second main pump 9 flows into the switching valve 14 of the second main valve 11 through the pipe 32, and the switching position C1
And is supplied to the extension side working chambers 26 of the hydraulic cylinders 5 for both booms.

At this time, the oil in the shortening side working chambers 28 of the hydraulic cylinders 5 for both booms respectively flows into the switching valve 13 through the pipe 29 and is switched at the switching position B1 so that the pipe 30
From the pipe 31 to the oil tank 7 via the pipe 24, and at the same time, flows into the switching valve 14 through the pipe 34, and is switched at the switching position C1 to switch from the pipe 35 to the pipe.
The oil is collected in the oil tank 7 through 36 and further through the pipe 37.

As described above, the hydraulic cylinders 5 for both booms are
The amount of pressure oil supplied to the extension side working chamber 26 is the sum of the amount supplied from the first main pump 8 and the amount supplied from the second main pump 9, and correspondingly, for both booms The amount of pressure oil discharged from the shortening working chamber 28 of the hydraulic cylinder 5 is 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
Since both the amount of pressure oil supplied to the boom-side working chamber 28 and the amount of pressure oil discharged from the shortening side working chamber 28 can be increased more than usual, the piston rods 27 of the hydraulic cylinders 5 for both booms extend at a high speed, and the boom It is possible to rotate 3 upward at a higher speed than usual. When the boom 3 is rotated downward at a higher speed than usual, one switching valve 12 of the first main valve 10 is switched to the neutral position A2 and 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, a 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.

[0034]

As described above, according to the first aspect of the present invention, when only one working device is operated, one main pump is driven to supply pressure oil to one hydraulic cylinder, and The main valve may be used to switch the flow of pressure oil supplied to the one hydraulic cylinder.

By driving the plurality of main pumps to supply the pressure oil to the plurality of hydraulic cylinders, and switching the flow of the pressure oil supplied to the plurality of hydraulic cylinders by using the plurality of main valves. , Multiple working devices can be operated simultaneously.

As described above, not only the plurality of working devices can be operated separately, but also the plurality of working devices can be simultaneously operated, so that the work can be performed quickly. According to the second aspect 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. By switching the flow of pressure oil supplied from the first main pump using the first main valve and switching the flow of pressure oil supplied from the second main pump using the second main valve, The boom and boom can be operated simultaneously. Therefore, excavation work or the like can be performed quickly.

According to the third aspect of the present invention, the first main valve is switched to supply the pressure oil supplied from the first main pump to the boom hydraulic cylinder, and the pressure oil supplied from the second main pump is supplied to the first hydraulic pump. By supplying the boom hydraulic cylinder with the two main valves, the amount of pressure oil supplied to the boom hydraulic cylinder becomes the sum of the supply amount from the first main pump and the supply amount from the second main pump. . As described above, the amount of pressure oil supplied to the boom hydraulic cylinder can be increased more than usual, so that the boom can be operated faster than usual.

[Brief description of 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 according to another embodiment of the present invention.

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

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

[Explanation of symbols]

 1 Wheel Loader (Industrial Vehicle) 2 Bucket (Working Device) 3 Boom (Working Device) 4 Bucket Hydraulic Cylinder 5 Boom Hydraulic Cylinder 8 1st Main Pump 9 2nd Main Pump 10 1st Main Valve 11 2nd Main Valve

Claims (3)

[Claims] 1. An industrial vehicle is provided with a plurality of main pumps for supplying pressure oil to a plurality of hydraulic cylinders for operating a plurality of work devices, and a plurality of main pumps for switching the flow of pressure oil supplied from each of these main pumps. A hydraulic circuit, wherein a valve is provided for each type of the hydraulic cylinders. 2. An industrial vehicle is a wheel loader, a work device is a bucket and a boom, hydraulic cylinders are a bucket hydraulic cylinder for operating a bucket and a boom hydraulic cylinder for operating a boom, and a main pump is for each. A first main pump that supplies pressure oil to the bucket hydraulic cylinder and a second main pump that supplies pressure oil to the boom hydraulic cylinder are used, and main valves are respectively provided for the pressure oil supplied from the first main pump. The first main valve for switching the flow and the second
The hydraulic circuit according to claim 1, wherein the hydraulic circuit is a second main valve that switches the flow of pressure oil supplied from the main pump. 3. A first main valve selectively supplies pressure oil supplied from a first main pump to either one of a bucket hydraulic cylinder and a boom hydraulic cylinder, and a second main valve supplies the pressure oil. 2. The hydraulic circuit according to claim 2, wherein the pressure oil supplied from the two main pumps is supplied to the boom hydraulic cylinder.