JPH0749667B2 - Hydraulic device for operation of parallel movement of attachment of agricultural loader - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention provides an attachment (for example, a bucket, a haze cutter, or an aerial work platform) of an agricultural loader detachably mounted on a tractor according to required work. The present invention relates to a hydraulic device for performing a parallel movement operation in a substantially horizontal state or in an inclined state.

<Prior Art> As this type of hydraulic operation, many proposals have been made in the past. For example, as shown in FIG. 8 and FIG.
Japanese Patent Laid-Open No. 60-44457 discloses a hydraulic operation proposed by the applicant.

It is a hydraulic pump 11 that constitutes the hydraulic system of the agricultural loader 1.
On the other hand, the lift cylinder 4 is connected by the lift operation valve 12a so that it can be expanded and contracted, and the dump cylinder 7 is connected by the dump operation valve 13b so that it can be expanded and contracted.
A parallel movement cylinder 5 is attached to the mechanically driven expandable / contractible cylinder, and the parallel movement cylinder 5 is integrally formed with the lift operation valve 12a via a parallel movement operation circuit.
And the lift cylinder 3 is expanded and contracted by operating the lift operation valve 12a to drive the lift arm 3 up and down, the parallel movement cylinder 5 expands and contracts to operate the dump cylinder 7 in response to this. The attachment 6 is configured to be in an attachment automatic parallel movement state in which the attachment 6 is moved in parallel while adjusting the swing.

That is, the lift operation valve 12a is configured to be switchable between the parallel rising position L, the stop position M, and the parallel lower rising position N. For the parallel rising position L and the parallel lowering position N where the attachment 6 moves in parallel, , Oil chamber 5a of translation cylinder 5
And the rake drive side oil chamber 7b of the dump cylinder 7 are communicated with each other, and the dump drive side oil chamber 7a of the dump cylinder 7 and the lift drive side oil chamber 4a of the lift cylinder 4 are communicated with each other. The oil chamber of the translation cylinder 5
The communication between 5a and the rake drive side oil chamber 7b of the dump cylinder 7 is cut off, and the communication between the dump drive side oil chamber 5a and the lift drive side oil chamber 4a of the lift cylinder 4 is also cut off. .

In these figures, reference numeral 2 is a relief valve,
25 is a tank.

<Problems to be Solved by the Invention> In the conventional example described above, the lift operation valve 12a is configured as a three-position switching valve dedicated to parallel movement operation, and the tractor is standardly equipped as a hydraulic device of an agricultural loader. The 3-position switching valve cannot be used as it is as a lift control valve, and the parallel movement control circuit is integrated in the 3 position control valve.
Since the position 7 connecting valve is used, the valve structure is complicated and cannot be implemented inexpensively.

In addition, since the valve device 12a added for parallel movement of the attachment cannot be made small, it requires a lot of labor for its installation and piping to install it in a narrow space, and it is not possible to improve the work efficiency of assembly. .

Moreover, when the lift arm 3 is moved up and down by the lift operation valve 12a, the attachment 6 always moves in parallel, so that the attachment 6 cannot be lift-driven with the posture fixed to the lift arm.

Moreover, since the lift operation valve 12a is additionally equipped as a dedicated valve, it cannot be provided at a position where it can be easily operated from the beginning, resulting in poor operability.

<Means for Solving Problems> The present invention has been made to solve the above problems,
The conventional hydraulic device for parallel movement of attachment is improved as follows.

That is, the lift operating valve 12 that is standardly equipped with the hydraulic device for agricultural loaders is used as it is, and the lift operating valve 12 is also used.
A selection valve 16 for parallel movement operation is provided independently of the above.

This parallel movement operation selection valve 16 comprises a parallel movement operation position K and a parallel movement rest position J, and the parallel movement operation position K of this selection valve 16 is the oil chamber 5a of the parallel movement cylinder 5 and the dump cylinder 7. While communicating with the scoop drive side oil chamber 7b and the dump drive side oil chamber 7a of the dump cylinder 7 and the ascending drive side oil chamber 4a of the lift cylinder 4, the parallel movement of the selection valve 16 is stopped. Position J is the oil chamber 5a of the translation cylinder 5 and the rake drive side oil chamber 7b of the dump cylinder 7.
It is characterized in that the communication between the dump drive side oil chamber 7a and the lift drive side oil chamber 4a of the lift cylinder 4 is also blocked.

<Operation> In the present invention, the lift operation valve 12 that is standardly equipped in the hydraulic device for agricultural loaders is used as it is, and the parallel operation selection valve 16 is provided independently of the lift operation valve 12, and the selection valve 16 is provided. Is basically the translation operation position K,
A two-position switching valve having a parallel movement rest position J,
When the attachment 6 is moved in parallel, the selection valve 16 is selected at the parallel movement operation position K, and the lift operation valve 12 moves the lift arm 3 up and down.

When the attachment 6 is lift-driven while the posture is fixed to the lift arm 3, the selection valve 16 is selected to the parallel movement rest position J to block the movement of the dump cylinder 7, and the lift operation valve 12 is used to lift the lift arm. Raise and lower only 3.

<Embodiment> FIGS. 1 and 2 are schematic views of a hydraulic system showing an embodiment of the present invention. FIG. 1 shows a mode in which the attachment 6 is raised in parallel, and FIG. The mode at the time of making is shown.

In these drawings, reference numeral 1 denotes an agricultural loader, which is mounted on a tractor (not shown) so as to be replaceable via a base 2, and the base 2 is pivotally supported at its base end to move up and down. Lift arm 3 movably provided, and lift arm 3
A double-acting lift cylinder 4 that vertically swings, a single-acting parallel-moving cylinder 5 that expands and contracts in response to the vertical swing of the lift arm 3, and a pivotally detachable support at the tip of the lift arm 3. Attachment (bucket) 6 and double-acting dump cylinder 7 that swings the attachment 6 up and down
It is equipped with.

The hydraulic device for parallel movement of the attachment is a hydraulic pump 11 that is standardly equipped with the hydraulic device of the agricultural loader.
Similarly, in addition to the lift operation valve 12 and the dump operation valve 13, an auxiliary valve device 15 is provided, and this auxiliary valve device 15 is provided with a parallel movement operation selection valve 16 which is a characteristic part of the present invention.

That is, the hydraulic pump 11 that constitutes the hydraulic device of the agricultural loader 1
On the other hand, the lift cylinder 4 is connected by the lift operation valve 12 so that it can be expanded and contracted, the dump cylinder 7 is connected by the dump operation valve 13 so that it can be expanded and contracted, and the translation cylinder 5 is mechanically driven by the lift cylinder 4. Attachable to expand and contract,
In the state where the parallel movement cylinder 5 is connected to the dump cylinder 7 through the parallel movement operation selection valve 16 and the lift operation valve 12 is operated to extend and contract the lift cylinder 4 to drive the lift arm 3 up and down. Following this, the parallel movement cylinder 5 expands and contracts to actuate the dump cylinder 7 to move the attachment 6 in parallel while adjusting the swing of the attachment 6 to be in an attachment automatic parallel movement state.

The auxiliary valve device 15 is configured independently of the lift operation valve 12 and is provided so as to intervene in the parallel movement oil passages 8 and 9 connecting the parallel movement cylinder 5 and the dump cylinder 7.
As shown in the figure, the parallel movement operation selection valve 16 which is a general-purpose two-position switching valve is provided.

The selection valve 16 has a parallel movement operation stop position J and a parallel movement operation position K, and is configured so that two-position switching control can be performed with a selection valve operation switch 17, and the lift operation valve 12 is operated with an operation handle 27. However, by appropriately turning on the switch 17, the attachment 6 can be moved in parallel.

In order to raise the attachment 6 in parallel, the lift operation valve 12 is moved to the raised position A while the dump operation valve 13 is in the neutral position F as shown in FIG. Turn 17 on. Then, the selection valve 16 is switched from the parallel movement stop position J to the parallel movement operation position K, and the oil chamber 5a of the parallel movement cylinder 5 and the rake drive side oil chamber 7b of the dump cylinder 7 communicate with each other.
The dump drive side oil chamber 7a of the dump cylinder 7 and the lift drive side oil chamber 4a of the lift cylinder 4 communicate with each other. In this state, the pressure oil from the pump 11 flows into the ascending drive side oil chamber 4a of the lift cylinder 4 and the oil passage 8b of the auxiliary valve device 15, and the oil flowing out from the descending side oil chamber 4b of the lift cylinder 4 is stored in the tank. Return to 25.

The pressure oil that has flowed into the oil passage 8b flows into the dump drive side oil chamber 7a of the dump cylinder 7 via the selection valve 16, and the rake drive side oil chamber
The oil flowing out from 7b flows into the oil chamber 5a of the parallel movement cylinder 5 through the selection valve 16.

At this time, since the oil chamber 5a of the translation cylinder 5 is filled with oil, the return oil from the dump cylinder 7 flows into the oil chamber 5a by an amount corresponding to the extension of the translation cylinder 5 and the dump cylinder 5a. 7 is extended by that amount. This causes the attachment 6 to rise in parallel. The cylinder cross-sectional area of the dump cylinder 7 and the rod cross-sectional area of the parallel movement cylinder are appropriately set so as to maintain the parallel movement of the attachment 6.

In order to lower the attachment 6 in parallel, as shown in FIG. 2, the lift control valve 12 is moved to the lowered position C while the dump control valve 13 is kept in the neutral position F, and the operation switch is moved to any position desired to be raised in parallel. Turn 17 on. Then, contrary to the above, oil flows, and the attachment 6 descends in parallel.

Further, when the parallel movement of the attachment 6 is not required, the operation switch 17 can be turned off at any time to stop the parallel movement of the attachment 6, and only the lift arm can be moved up and down.

1 and 2, the parallel movement operating circuit 15 is provided with a relief valve 19, check valves 20 and 21, and a pilot valve 22, and has the functions described below.

The relief valve 19 is provided when the attachment cylinder 6 descends in parallel (FIG. 2) and the dump cylinder 7 contracts most.
This is for returning the oil to the tank 25 via the relief valve 19 because there is no escape place for the oil in the translation cylinder 5.

The check valve 20 has a structure in which the oil chamber 5a of the parallel movement cylinder 5 is in a vacuum state when the attachment cylinder 6 rises in parallel (FIG. 1) and the dump cylinder 7 is most extended. It is for sending oil to the drive oil chamber 5a via the.

The check valve 21 and the pilot valve 22 are, for example, in FIG. 2, with the switch 17 turned on, the lift operating valve 12 is switched to the neutral position B and the dump operating valve 13 is switched to the rake position E to scoop the attachment 6. When operating, the lift drive side oil chamber 4a of the lift cylinder 4 communicates with the dump drive side oil chamber 7a of the dump cylinder 7 via the oil passage 9b, and also communicates with the tank 31 to lower the lift arm 3 by its own weight. This is to prevent it.

That is, the pilot valve 22 is driven by the pilot pressure of the oil passage 9a to the oil passage 9b.
To close.

FIG. 3 is a circuit diagram of a main part showing another embodiment of the selection valve. This selection valve 16A has a point that the oil passage 8a is bypassed by the neutral port 8c and communicated with the oil passage 8b at the parallel movement stop position J. Different from the above.

FIG. 4 shows another embodiment in which the selection valve 16B is a 5-port 3-position switching valve. The selection valve 16B is a dump cylinder 7
1 in that a speed increasing valve mechanism for increasing the speed of the dumping operation is additionally provided.

For example, the lift operation valve 12 is set to the neutral position B, the dump operation valve 13
To the dump operation position G, and the dump operation handle 28
When the speed increasing switch 18 is turned on, the selection valve 16B is set to the speed increasing position H, and the rake drive side oil chamber 7b of the dump cylinder 7 is turned on.
The return oil of (1) joins the dump drive side oil chamber 7a of the dump cylinder 7 via the selection valve 16B, and the dump speed of the dump cylinder 7 is increased.

FIG. 5 shows another embodiment in which a double-acting lift cylinder 4 and a single-acting parallel moving cylinder 5 are integrally assembled, and other points are the same as in FIG.

FIG. 6 shows another embodiment in which the lift cylinder 4 is configured by a single-acting type, and the circuit of the lift operation valve 12A is partially changed correspondingly, but other points are shown in FIG. Is the same as.

FIG. 7 shows another embodiment in which the single-acting lift cylinder 4 and the single-acting parallel movement cylinder 5 are integrally assembled, and other points are the same as those in FIG.

<Effects of the Invention> The present invention has the following effects because it is configured and operates as described above.

I. In the basic structure of the hydraulic system of the agricultural loader, as a valve device added to move the attachment in parallel with the lifting drive of the lift arm, in the conventional example shown in FIG. 8 and FIG. The 3-position 7-connection valve integrally combined with the operation circuit was used, and the valve structure was complicated, whereas the present invention basically uses only the 2-position 4-connection parallel movement operation selection valve. The valve structure is simple and can be implemented at low cost.

B. The valve device added for the parallel movement of the attachment is basically a simple valve having a 2-position 4-connection structure in the present invention. Since the valve can be made compact and the number of pipe connections can be reduced, the valve can be installed in a narrow space with a margin, and the installation and piping work can be reduced, improving the work efficiency of assembly. .

C. By operating the lift operation valve in a state where the parallel movement operation selection valve is placed in the parallel movement rest position, it is possible to operate only the lift cylinder and drive the lift while the posture of the attachment is fixed to the lift arm.

D. As the lift operation valve, the 3-position directional control valve, which is standard equipment from the beginning, is used as it is at a position where the tractor is easy to operate, so that the tractor can be operated easily and efficiently.

[Brief description of drawings]

1 and 2 are hydraulic circuit diagrams of a hydraulic system according to an embodiment of the present invention. FIG. 1 shows a parallel ascending state, and FIG. 2 shows a parallel descending mode. FIG. 3 is a circuit diagram of a main part showing another embodiment of the selection valve, FIG. 4 is a hydraulic circuit diagram including another selection valve, and FIG. 5 is a double-acting lift cylinder and a single-acting parallel moving cylinder. FIG. 6 is a circuit diagram according to another embodiment in which the above are assembled in a pair, and FIG. 6 is a circuit diagram according to another embodiment in which the lift cylinder and the parallel movement cylinder are configured by a single-acting type.
FIG. 7 is a circuit diagram of another embodiment in which the lift cylinder and the parallel movement cylinder are single-acting type and are integrally assembled. FIG. 8 and FIG. 9 are hydraulic circuit diagrams showing a conventional example, respectively. FIG. 8 shows a mode during parallel rising, and FIG. 9 shows a mode during parallel falling. 1 ... agricultural loader, 3 ... lift arm, 4 ... lift cylinder, 4a ... ascending drive side oil chamber, 5 ... translation cylinder, 5a ... oil chamber, 7 ... dump cylinder, 7a ... Dump drive side oil chamber, 7b …… Scoop drive side oil chamber, 8 (8a ・ 8
b) ・ 9 (9a ・ 9b) …… Oil passage, 11 …… Pump, 12 …… Lift operation valve, 13 …… Dump operation valve, 16 …… Selection valve (parallel movement operation circuit).

Claims (1)

[Claims] 1. A lift cylinder 4 is connected to a hydraulic pump 11 constituting a hydraulic device of an agricultural loader 1 so that it can be expanded and contracted by a lift operation valve 12, and a dump cylinder 7 can be expanded and contracted by a dump operation valve 13. The parallel movement cylinder 5 is attached to the lift cylinder 4 so as to be mechanically driven to expand and contract, and the parallel movement cylinder 5 is connected to the dump cylinder 7 through the parallel movement operation circuit to operate the lift operation valve 12. In the state where the lift cylinder 4 is expanded and contracted to drive the lift arm 3 up and down, the parallel movement cylinder 5 expands and contracts to operate the dump cylinder 7 and move the attachment 6 in parallel while adjusting the swing. In the hydraulic device for operating the attachment parallel movement of the agricultural loader, which is configured to be in the automatic parallel movement state of the attachment, The working circuit is composed of a parallel movement operation selection valve 16 independent of the lift operation valve 12, and this selection valve 16 is provided with a parallel movement operation position K and a parallel movement rest position J. The parallel movement operation position K is the oil chamber 5a of the parallel movement cylinder 5 and the rake drive side oil chamber 7b of the dump cylinder 7.
And the communication between the dump drive side oil chamber 7a of the dump cylinder 7 and the ascending drive side oil chamber 4a of the lift cylinder 4 while the parallel movement pause position J of the selection valve 16 is for parallel movement. Oil chamber 5a of cylinder 5 and rake drive side oil chamber of dump cylinder 7
For parallel movement operation of attachment of agricultural loader, characterized in that the communication with the dump drive side oil chamber 7a and the lift drive side oil chamber 4a of the lift cylinder 4 are also blocked. Hydraulic system