JPS6022137B2 - Bucket operation control device for tractor shovels, etc. - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a hydraulic control circuit for a built-in device for earth-moving machinery such as a tractor shovel, and its purpose is to automatically prevent the load from falling when raising and lowering the load. The object of the present invention is to provide a bucket operation control device for controlling the posture of a Kukumihishitaka.

Generally, as shown in Fig. 1, a loading device for an earthmoving machine connects a lift arm 2 attached to a machine frame 1 to a lift cylinder 3.
The bucket cylinder 5 is raised and lowered by the operation of the bucket cylinder 5.
The bucket 4 supported at the tip of the lift arm 2 can be lifted up and down by the operation of the lift arm 2, and is used to carry out a series of operations such as excavating, loading and unloading earth, sand, rocks, etc. The present invention achieves the above object in this type of device, and FIG. 2 shows an embodiment of the operating hydraulic circuit of the present invention in a loading device as shown in FIG.

6 is an engine; 7 is a constant discharge type hydraulic pump driven by the engine 6; the hydraulic pump 7 supplies pressure oil to the lift cylinder 3 and the bucket cylinder 5;

Reference numeral 8 indicates a directional switching valve for controlling the lift cylinder (hereinafter simply referred to as the lift switching valve); 9 indicates a directional switching valve for controlling the bucket cylinder (hereinafter simply referred to as the bucket switching valve); 11
is a flow dividing/concentrating device, for example, a synchronized valve consisting of a pair of constant displacement hydraulic pump/motors 11a and 11b,
When a certain amount of oil flows into 11a, 11a acts as a motor and rotates the pump 11b synchronously.
If the amount of oil discharged from the pump motor 11b is arbitrarily set, the set amount is discharged from the pump/motor 11b.

The upflow side boat of the synchronized valve 11 is followed by the lift switching valve 8 and piping 23, and the diverting side boats of the synchronized valve 11 are connected to the rod side chambers 3b, 5b of the lift cylinder 3 and bucket cylinder 5 with piping 14, 13, respectively. A relief valve 19 and a check valve 16 are interposed in the middle of the branch pipe 13, and a branch pipe is connected to the tank 201.

A relief valve 17 and a check valve 15 are connected to the piston side chamber 5a of the bucket cylinder 5 through a piping 22 so as to face the tank 20', and also connected to the bucket switching valve 9 via a piping 21 to form the piston side chamber 5a of the bucket cylinder 5. It is configured to be able to supply pressure oil to.
Note that the flow dividing/concentrating device 11 is not limited to a tuned valve, but also a third valve.
As shown in the figure, the same effects as described below can be obtained even with a flow dividing valve equipped with a pair of throttles 11a and 11b, which allow the flow rate of oil to be set in advance and flowed at an arbitrary ratio.
To explain the operation of the embodiment of the present invention configured as above, first, when the lift cylinder 3 is raised, the high pressure oil discharged from the hydraulic pump 7 by the drive of the engine 6 is guided to the lift switching valve 8. I'm scared.

When the boat of the switching valve 8 is switched from the neutral position B to the neutral position C in order to raise the lift arm 2 (see FIG. 1), high pressure oil flows into the piston side chamber 3a of the lift cylinder 3. At this time, the oil accumulated in the rod side chamber 3b of the lift cylinder 3 is pushed out and passed through the hydraulic pump/motor 11a of the synchronized valve 11 from the C position of the switching valve 8 to the tank 201.
This flows down. At this time, a certain amount of oil passes through the hydraulic pump/motor 11a, so this hydraulic pump/motor 11a acts as a motor, and the other hydraulic pump/motor lb
Rotate synchronously. As a result, a set flow rate of oil flows out from the hydraulic pump/motor 11b acting as a pump, and the oil in the rod side chamber 5b of the bucket cylinder 5 passes through the pipes 12 and 13 to the hydraulic pump/motor 11b acting as a pump. Along with this, the pipe 23-
It flows down into the tank 20 via the lift switching valve 8. Accordingly, the piston on the bucket cylinder 5 side moves, and an amount of oil sufficient to replenish the space created in the piston side chamber 5a flows from the tank 20 through the check valve 15 into the piston side chamber 5a of the bucket cylinder 5. In this way, the lift cylinder 3 is raised and the bucket cylinder 5 is moved in the vertical direction, and the bucket 4 is smoothly and automatically extended (
(forward tilt) operation control is possible. Note that if you try to raise the lift cylinder 3 when the bucket cylinder 5 is at the lowering end, the return oil from the bucket cylinder 5 will run out, so one of the hydraulic pump motors 1 1a will not be able to handle the discharge from the lift cylinder 3. Although it attempts to rotate using oil, the other hydraulic pump/motor 11b cannot rotate, and the synchronous valve 11 becomes inoperable. However, in this case, since oil is sucked from the check valve 16 and supplied to the hydraulic pump/motor 11b side of the synchronization valve 11, the synchronization valve 11 operates, allowing the lift arm to rise. Next, when lowering the lift cylinder 3, when the boat of the lift cylinder control directional control valve 8 is switched to A, high pressure oil flows into the synchronization valve 11 in the opposite direction to the above-mentioned upward movement, and the hydraulic pump/motor la, 11b Distribute oil at a preset constant ratio to the rod side chamber 3b of the lift cylinder 3 and the rod side chamber 5b of the bucket cylinder 5.
At the same time, the bucket cylinder 5 is operated in conjunction with the bucket cylinder 5 to give the bucket 4 (FIG. 1) a supine (backward) action.

Note that the return oil from the bucket cylinder 5 returns to the tank 20 via the relief valve 17.

At this time, if the quantitative balance between the oil flowing out from the piston side chamber 3a and the oil flowing into the rod side chamber 3b in the rod side chamber 3b of the lift cylinder IJ cylinder 3 is lost and the oil supply is insufficient, the oil is replenished by the check valve 18. Also, if bucket cylinder 5
When the lift cylinder 3 is lowered when it is at the supine end, the hydraulic pump/motor 11 of the synchronized valve 11
The high pressure oil flowing out from the b side can return to the tank 20 by operating the relief valve 19. As explained in detail above, according to the hydraulic control circuit according to the present invention, when raising and lowering the lift arm, the lift cut-off valve 8
By simply operating the bucket cylinder, the bucket posture can be smoothly and automatically controlled by interlocking the bucket cylinder, and the bucket operation can be freely controlled by setting the flow rates of the synchronized valve's hydraulic pump and motor to any desired ratio. As a result, the bucket always maintains a proper posture while the IJ foot arm is being raised and lowered, and the load in the bucket will not fall during work.

Furthermore, components such as mechanical leveling that obstruct the field of vision are not required, and the circuit of the present invention can be installed in any small space. As described above, the present invention is highly economical and greatly contributes to improved work efficiency and safety.

[Brief explanation of the drawing]

FIG. 1 is a side view of a tractor shovel, FIG. 2 is a hydraulic control circuit diagram showing an embodiment of the present invention, and FIG. 3 is a hydraulic control circuit diagram showing another embodiment. 3...Lift cylinder, 5...Nocket cylinder, 8
...Directional sliding valve for lift cylinder control, 9...
... Directional switching valve for bucket cylinder control, 11. ．． ．．・
...Dividing and collecting flow equipment, 15, 16... Check valve, 17, 19... Relief valve. Figure 1 Figure 2 Figure 3

Claims (1)

[Claims] 1 Switching the hydraulic pressure to the lift cylinder that raises and lowers the lift arm, the bucket cylinder that raises and lowers the bucket supported at the tip of the lift arm, the hydraulic pump that supplies pressure oil to both of the cylinders, and the hydraulic pressure to the lift cylinder. In a tractor shovel, etc. equipped with a directional control valve for controlling the lift cylinder and a directional control valve for controlling the bucket cylinder that switches pressure oil to the bucket cylinder, the rod side chamber of the lift cylinder and the directional control valve for controlling the lift cylinder are connected to each other. At the branch point of the branch pipe that branches from the pipe that communicates with the rod side chamber of the bucket cylinder, there is a pipe that connects the boat on the collection side to the directional switching valve for controlling the lift cylinder, and a boat on the diverter side that communicates with the directional switching valve for controlling the lift cylinder. In addition to interposing flow dividing and collecting equipment connected to the pipes communicating with the side chambers of both rods,
A bucket operation control device for a tractor shovel, etc., characterized in that a relief valve and a check valve are connected via piping to the piston side chamber of the bucket cylinder.