JP2003092904A - Apparatus for lifting implement - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an apparatus for lifting an implement capable of selecting a form lowering the implement by own weight and a forcible lowering form by pressure of a lift cylinder and reducing a cost. SOLUTION: This apparatus for lifting can operate one lift cylinder as a double-acting hydraulic cylinder 13 and operate the other lift cylinders as single- acting hydraulic cylinders 12 among a plurality of lift cylinders for operating lift arms 9. All of these lift cylinders are used as single-acting hydraulic cylinders when the implement is normally lowered and one lift cylinder which can be operated as the lift cylinder 13 is changed to the double-acting type hydraulic cylinder 13 when the implement is forcibly lowered.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a working machine lifting device for controlling a working machine mounted on a mobile agricultural machine such as an agricultural tractor by operating a lift arm by a plurality of lift cylinders.

[0002]

2. Description of the Related Art Conventionally, a lift arm is provided at the front or rear of a mobile agricultural machine such as an agricultural tractor, and a working machine suspended by the lift arm is extended and contracted by a lift cylinder connected to the lift arm. There is known a work machine lifting device that is controlled to move up and down. In addition, a single-acting hydraulic cylinder is generally used as a lift cylinder in this type of working machine lifting device, and when raising the working machine, pressure oil is supplied to the hydraulic cylinder to extend the piston rod, Further, when the working machine is lowered, the piston rod is retracted by the weight of the working machine to lower the working machine.

In the above-described working machine lifting device, when the working machine mounted on the lift arm encounters a hard rock or the like in the ground and a lifting force is applied, the working machine is relatively freely retracted upward. While the work machine can be prevented from being damaged,
Since the work implement descends due to the weight of the work implement itself, it is not possible to obtain the planned working depth from the beginning in order to prevent the work implement from immediately entering the ground in a hard field, and the unplowed part is There are problems such as many occurrences. Therefore, in order to solve the problem that the unplowed portion occurs in the latter while leaving the former advantage of preventing damage to the working machine, the lift cylinder of the working machine lifting device is changed to a double-acting hydraulic cylinder. None, this double-acting hydraulic cylinder is always used as a single-acting type to control the work machine up and down, and at the start of work on a hard field, etc., the single-acting type is switched to the double-acting type. It was considered that the working machine was forcibly lowered by hydraulic pressure by supplying the pressure oil to the pressure chamber on the descending side of the cylinder.

[0004]

However, in the working machine lifting apparatus employing such a double-acting hydraulic cylinder, the lift force for lifting the working machine is increased by connecting a plurality of lift cylinders to the lift arm. It is possible to install heavy work equipment by increasing the number of lift cylinders.In this case, if all of the plurality of lift cylinders are double-acting hydraulic cylinders, the hydraulic cylinder itself and There is a problem of high cost. Therefore, in view of these problems, the present invention intends to provide a working machine lifting device capable of suppressing the cost increase while leaving the advantage of switching from the single-acting type to the double-acting type.

[0005]

In order to solve the above-mentioned problems, a working machine lifting device of the present invention controls a working machine up and down by operating a lift arm by a plurality of lift cylinders. , One is a double-acting hydraulic cylinder, the remaining lift cylinders are single-acting hydraulic cylinders, and all of these lift cylinders are always used as single-acting hydraulic cylinders when the working machine descends. The working machine is lowered by its own weight, and when the working machine is forcibly lowered, one lift cylinder, which is the double-acting hydraulic cylinder, is switched to the double-acting type and the lift cylinder is operated by the operation. It is characterized in that the working machine is configured to be forcibly lowered. Further, when the working machine is forcibly lowered, while supplying pressure oil to the downward pressure chamber of the lift cylinder, which is a double-acting hydraulic cylinder,
It is characterized in that the control valve is switched and controlled so that the oil is drained from the rising pressure chamber of the lift cylinder. Further, control the forced lowering of the working machine based on the continuous lowering command of the lowering operation tool so as to switch from the previous lowered state due to the weight of the working machine to the forced lowering state using the double-acting hydraulic cylinder. Is characterized by.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described with reference to the drawings. As shown in FIGS. 1 and 2, an agricultural tractor 1 includes a pair of left and right crawler traveling devices 3 and 3 at a lower portion of a body frame 2, and an engine (not shown) provided in a hood 4 provided at a front portion of the body frame 2. It is equipped with.
In addition, the cabin 5 arranged in the substantially central portion of the body frame 2
There is a driver's seat 6 inside, and a rotary tiller at the rear of the machine,
It is equipped with a working machine lifting device 7 for mounting a working machine such as a plow. The working machine lifting device 7 includes a pair of left and right lift arms 9 and 9 rotatably pivoted on an upper portion of a mounting plate 8 standing upright on the rear of the machine body, and lift rods 10 and 10 at the tips of the lift arms 9 and 9. And left and right lower links 11 and 11 connected through the left and right, and left and right lift cylinders 12 and 13 that connect the lower ends to the body frame 2 and the upper ends to the middle portions of the left and right lift arms 9 and 9, A three-point link hitch is also commonly used in the work machine lifting device 7.

The left and right lift cylinders 12, 13 are
As shown in FIG. 3, all of them are hydraulic cylinders. Among them, one hydraulic cylinder 12 is a single-acting hydraulic cylinder, and the remaining one hydraulic cylinder 13 is a double-acting hydraulic cylinder. I am doing it. Further, the pressure chambers a, a of the left and right lift cylinders 12, 13 are driven by the engine via a descending speed adjusting valve 14, a control valve (control valve) 15 for controlling ascending and descending, and a diversion valve 16. The pressure chamber b of the lift cylinder 13 connected to the hydraulic pump 17 is a double-acting hydraulic cylinder.
It is connected to the hydraulic pump 17 via 8.

More specifically, the control valve 15
Includes an ascending switching valve 19 and a descending switching valve 20, and each of the switching valves 19 and 20 is an ascending electromagnetic proportional valve 2 formed of an electromagnetic proportional valve.
1 and the pilot pressure of the descending solenoid proportional valve 22, the rising solenoid proportional valve 21 is energized, and when the pilot switching causes the rise switching valve 19 to switch from the state shown in the figure to the left, the hydraulic pump 17 The pressure oil from is supplied to the ascending side pressure chambers a and a of the left and right lift cylinders 12 and 13 via a shunt valve 16, an ascending switching valve 19, and a check valve 14a provided in parallel with the descending speed adjusting valve 14, respectively. The piston rods 12a and 13a extend and the lift arms 9 and 9 rotate upward, whereby the working machine rises. Further, when the downward electromagnetic proportional valve 22 is energized and the pilot pressure causes the downward switching valve 20 to switch from the state shown in the drawing to the left, the lifting side pressure chambers a of the left and right lift cylinders 12 and 13 due to the weight of the working machine. , A is discharged from the lift arm 9, while being squeezed by the descending speed adjusting valve 14 and flowing back to the tank T through the descending switching valve 20. 9 descends and rotates, and the working machine descends at the descending speed set by the descending speed adjusting valve 14. And
When the solenoid proportional valves 21 and 22 are not energized, the control valve 15 shuts off the supply and discharge of the pressure oil to and from the rising pressure chambers a of the left and right lift cylinders 12 and 13, and the working machine It is stopped and held at the lifted position. Reference numeral 23 is a lift safety valve for the left and right lift cylinders 12, 13 and 24 is a lift rod cylinder. If one of the lift rods 10, 10 described above is replaced with this lift rod cylinder 24, the attitude control of the working machine with respect to the machine body is performed. The lift rod cylinder 24 is connected to the hydraulic pump 17 via the electromagnetic switching valve 25 and the flow dividing valve 16.

Next, the raising / lowering control of the working machine will be described with reference to FIGS. 4 and 5. Reference numeral 26 denotes a controller for raising / lowering the working machine, which is a well-known microcomputer,
It is composed of a RAM, a ROM, an input circuit, a driver on the output side, and the like. Then, in the input circuit of the controller 26,
Lifting switch operated in the control section (raising operation tool)
27, a lowering switch (lowering operation tool) 28, a potentiometer 29 for detecting the operating position of a position lever provided for setting the up / down position of the working machine, and an upper limit setting device for setting the upper limit when the working machine is raised. 30, a lift arm sensor 31 for detecting an ascending / descending position of the working machine with respect to the machine body, and the like are connected to the driver on the output side. Solenoids 18a and the like of the electromagnetic switching valve 18 for forced lowering are respectively connected.

When the operator turns on the raising switch 27 for a short time, the controller 26 energizes the raising solenoid 21u, and when the raising solenoid 21u is energized, the raising switching valve 19 is operated as described above.
Is switched, and the working machine is raised by the upward rotation of the lift arms 9, 9. Further, when the working machine rises and the detection value of the lift arm sensor 31 and the value set by the upper limit setting unit 30 match, the controller 26 causes the raising solenoid 21 to move.
The energization of u is stopped, and the working machine is stopped and held at the raised position set by the upper limit setting unit 30. On the other hand, when the operator turns on the lowering switch 28 for a short time, the controller 26 energizes the lowering solenoid 22d, and when the lowering solenoid 22d is energized, the lowering switching valve 2 as described above.
0 is switched and the working machine descends by its own weight. When the working machine descends and the detected value of the lift arm sensor 31 and the value of the potentiometer 29 for detecting the operating position of the position lever match, the controller 26 stops energizing the descending solenoid 22d, and the working machine moves to the position lever. To the position set by.

Further, when the operator continuously turns on the lowering switch 28 for a set time or longer,
The controller 26 continues to energize the descending solenoid 22d, and the ascending side pressure chamber a of the lift cylinders 12 and 13
Solenoid switching valve 1 for forcibly lowering the oil while prompting drainage from a
The solenoid 18a of No. 8 is energized, the electromagnetic switching valve 18 is switched by it, and pressure oil is supplied from the hydraulic pump 17 to the descending side pressure chamber b of one lift cylinder 13, which is a double-acting hydraulic cylinder. In addition to its own weight, the work machine is forcibly lowered by the downward rotation of the lift arms 9, 9. Also, the lowering switch 28 is continuously turned on.
By operation, the working machine is sufficiently digged into the ground, and if the lowering switch 28 is turned off, the lowering solenoid 22d
To the solenoid 18a of the electromagnetic switching valve 18 is stopped, and the forced lowering control ends. In addition, the raising / lowering control of the working machine is performed by the above-mentioned raising / lowering switches 27, 28.
In addition to the control by the
When 8 is not operated, it can be controlled also by a position lever for controlling the position of the working machine or a tilling depth sensor attached to the rotary tiller.

[0012]

As described above, according to the present invention, one of the plurality of lift cylinders for operating the lift arm 9 is the double-acting hydraulic cylinder 13 and the remaining lift cylinder is the single-acting hydraulic cylinder 12. Normally, any of these lift cylinders is used as a single-acting hydraulic cylinder so that the work machine is lowered by its own weight when the work machine is lowered, and when the work machine is forcibly lowered, the double-action cylinder is used. Since one lift cylinder 13, which is a hydraulic cylinder of a mold, is switched to a double-acting type and the working machine is forcibly lowered by the operation of the lift cylinder, a heavy work by a plurality of lift cylinders is performed. Can be fully raised by the machine, and when lowering the working machine, it can be lowered normally by the weight of the working machine or a double-acting hydraulic cylinder. Both forms of forced downward using is able to select, it is possible to enhance the adaptability of the work by the work machine. And, in such a working machine descending mode, if all of the plurality of lift cylinders are double-acting hydraulic cylinders, the hydraulic cylinder itself and the hydraulic piping for the hydraulic cylinder are costly. However, in the case of the present invention, one of the lift cylinders 13 is a double-acting hydraulic cylinder and the remaining lift cylinders 12 are single-acting hydraulic cylinders, so that the entire apparatus can be inexpensively manufactured. . In addition, when the working machine is forcibly lowered, the lowering operation is added due to the weight of the working machine.
The working machine can be forcibly lowered even by the forcible lowering operation of No. 3, and furthermore, the working machine is excessively forcibly lowered when all of the plurality of lift cylinders are double-acting hydraulic cylinders. It is possible to prevent the possibility that the product will be damaged. Further, when the working machine is forcibly lowered, pressure oil is supplied to the lower pressure chamber b of the lift cylinder 13, which is a double-acting hydraulic cylinder, and the lift cylinders 12, 1
Control valve 1 so that oil is drained from the pressure chambers a,
When the switching control of 5 is performed, the retracting operation of the plurality of lift cylinders can be smoothly performed. Further, the forced lowering of the working machine is controlled based on the continuous lowering command of the lowering operation tool 28 so as to switch from the lowering state due to the weight of the working machine until then to the forced lowering state using the double-acting hydraulic cylinder 13. Then, since the forced lowering operation is added from the middle of the continuous lowering operation state of the working machine, the forced lowering operation of the working machine can be smoothly switched in a state where the shock is reduced. Moreover, since it is possible to determine the operation form of the descending operation tool 28 that originally commands the descending by the weight of the working machine and switch to the forced descending state without separately providing a forced descending operation tool, the operability is improved and the cost is low. It can be installed in

[Brief description of drawings]

FIG. 1 is a side view of an agricultural tractor.

FIG. 2 is a rear view of the agricultural tractor.

FIG. 3 is a hydraulic circuit diagram of a work machine lifting device.

FIG. 4 is a control circuit diagram of a work machine lifting device.

FIG. 5 is a lowering control flowchart of the work machine.

[Explanation of symbols]

1 agricultural tractor 9 Lift arm 12 Lift cylinder (single-acting hydraulic cylinder) 13 Lift cylinder (double-acting hydraulic cylinder) 15 Control valve 28 Down switch (down operation tool) a Ascending pressure chamber b Downward pressure chamber

Claims (3)

[Claims] 1. A lift arm is operated by a plurality of lift cylinders to control a work machine up and down, and one of the plurality of lift cylinders is a double-acting hydraulic cylinder, and the remaining lift cylinder is a single-acting type. No lift hydraulic cylinder, always using any of these lift cylinders as a single-acting hydraulic cylinder to lower the working machine by its own weight when lowering the working machine, and forcibly lowering the working machine. In the working machine lifting device, one lift cylinder, which is the double-acting hydraulic cylinder, is switched to the double-acting type and the working machine is forcibly lowered by the operation of the lift cylinder. 2. When the working machine is forcibly lowered, pressure oil is supplied to a descending pressure chamber of a lift cylinder, which is a double-acting hydraulic cylinder, and is discharged from an ascending pressure chamber of the lift cylinder. 1. The switching control of the control valve according to claim 1,
The work machine lifting device described. 3. The forcible lowering of the working machine is switched to a forcible lowering state using a double-acting hydraulic cylinder from a lowering state due to the weight of the working machine until then, based on a continuous lowering command of the lowering operation tool. The work implement lifting device according to claim 2, which is controlled by the above.