JPS5831441Y2 - tractor - Google Patents

Description

[Detailed description of the invention] This invention connects the oil supply and drainage passage of the hydraulic actuator for driving the attachment in series in the middle of the oil passage that supplies pressure oil to the control valve of the hydraulic cylinder for driving the lift arm installed in the aircraft. The present invention relates to an I-actor in which a connection portion is provided and a relief valve is provided in the middle of a pressure oil supply path from the control valve to the hydraulic cylinder.

The above tractor was originally designed to be able to operate Attachment I/drive hydraulic actuator with a simple piping configuration using a hydraulic circuit whose capacity was set for driving the lift arm. Even when driving the drive hydraulic actuator, the return oil is returned to the tank via the control valve to the lift arm drive hydraulic cylinder, that is, the pressure oil supply path to the lift arm drive hydraulic cylinder. The overall structure is simplified by using a part of the oil drain passage as well as the oil drainage passage for the attachment driving hydraulic actuator.

However, with the conventional structure configured in this way, when it becomes necessary to drive the lift 1 to arm drive hydraulic cylinder while the attachment I/drive hydraulic actuator is in use, the attachment I/drive hydraulic actuator Since the sum of both the drive load of the pump and the drive load of the lift arm drive hydraulic cylinder acts as the pump drive load, the pump was originally designed with the maximum drive load on the lift arm drive hydraulic cylinder side in mind. However, there is a risk of overloading the hydraulic pump.

Therefore, in order to avoid such a danger, the set pressure of the relief valve arranged in the pressure oil supply path to the hydraulic cylinder for driving the lift l-arm should be set sufficiently low, or the setting pressure should be set sufficiently low. In the former case, a separate relief valve corresponding to the maximum load of the hydraulic pump may be provided in the pressure oil supply path before reaching the attachment drive actuator. When using only the hydraulic cylinder for driving the lift arm without using an actuator, the relief pressure in the pressure oil supply path is too low to drive the lift arm with the desired large driving force. In addition, in the latter case, when the attachment drive hydraulic actuator and the lift arm drive hydraulic cylinder are used simultaneously, and when only the attachment drive hydraulic actuator is used alone, the attachment drive hydraulic actuator This results in a significant difference in the set relief pressure for the hydraulic actuator, which has the disadvantage that the required power required for the attachment drive hydraulic actuator cannot be stably secured.

The technical problem to be solved by the present invention is that, in one or more actuators equipped with a connection part for the attachment drive hydraulic actuator as described above, while stably securing the required power of the attachment drive hydraulic actuator, the attachment When the drive hydraulic actuator is not connected, the drive force from the glue 71 to the arm drive hydraulic cylinder is also secured as expected, and when both hydraulic systems are used simultaneously, the power from the attachment drive hydraulic actuator is The structure is configured so that the hydraulic cylinder for driving the lift arm is driven only when a load that can be lifted within the remaining power of the hydraulic pump is acting on the lift arm. The purpose is to avoid overloading.

The technical means of this invention taken to solve the above problems are as follows:
In the middle of the oil path that supplies pressure oil to the control valve of the hydraulic cylinder for driving the lift arm installed in the aircraft body, a connecting part is provided to connect the oil supply and drainage path of the hydraulic actuator for driving the attachment in series, and the control valve In a tractor in which a relief valve is provided in the middle of the pressure oil supply path from the hydraulic actuator to the hydraulic cylinder, a preliminary oil drain path that communicates with the tank is branched from the middle of the oil drain path of the hydraulic actuator, and a preliminary oil drain path is provided in the preliminary oil drain path. This is because a valve mechanism for adjusting the discharge amount is provided.

The effects obtained by taking the above technical measures are as follows.

In other words, a preliminary oil drainage path to a tank equipped with a valve mechanism for adjusting the drainage amount is connected in the middle of the oil drainage path from attachment 1 to the drive hydraulic actuator, so when both hydraulic devices are used at the same time. In addition, the sum of the individual loads of both hydraulic devices does not directly act as a driving load for the hydraulic pump, but is short-circuited with the driving load of the attachment drive hydraulic actuator and is discharged from the preliminary oil drain path to the tank side. The drive load on the knot arm drive hydraulic cylinder side, which is driven by the remaining pressure oil that was not present, can be used as the drive load for the hydraulic pump.
If the load on the hydraulic cylinder for driving the lift arm is close to the maximum value, there is a risk that this load and the drive load on the hydraulic actuator for driving the attachment will be added together and give an excessive load to the hydraulic pump. This can be avoided, and moreover, the required power of the attachment drive hydraulic actuator can be secured preferentially.

In addition, the setting pressure of the relief valve provided in the pressure oil supply path to the hydraulic cylinder for driving the lift arm can be determined as a setting pressure sufficient to drive the lift arm with the maximum load. When only the hydraulic cylinder is used alone, it can be driven with a large output that effectively utilizes the hydraulic pump driving force without wasting it.

Embodiments of the present invention will be described below with reference to the drawings.

A tilling device 2 that is moved up and down by a lift arm 1 is installed at the rear of the tractor body, and a shovel device 4 is installed at the front of the tractor body as an attachment that moves up and down via support frames 3. 1 steam support frames 3, 3 each have a single-acting hydraulic cylinder 5
It is configured to swing up and down by the expansion and contraction operations of the double-acting hydraulic cylinders 6, 6.

Next, the drive circuit for the hydraulic cylinders 5, 6.6 will be explained based on FIG. A relief valve 10 is provided in the middle of the oil passage a connecting the control valve 8 to the tank 9, and its oil drainage passage d is communicated with the oil drainage passage C from the control valve 8 to the tank 9.

Further, in the middle of the oil supply path connecting the valve 8 and the tank 9, there is an oil supply and discharge path e to the driving hydraulic cylinder 6.6 of the shovel device 4.

A connecting part 11 is provided to connect the oil supply/drainage passages e and f to the connecting part 11, so that the lift arm hydraulic circuit A and the attachment I and hydraulic circuit B can be arranged in series. It is.

In addition, a control valve 12 is interposed in the oil supply and discharge passages e and f to the hydraulic cylinder 6.6, and a relief valve 13 is interposed between the oil supply and discharge passages e and f, so that a control valve 12 is provided between the oil supply and discharge passages e and f. A preliminary oil drain path g communicating with the tank 9 is provided, and a variable throttle valve 14 is interposed in this oil drain path g as a valve mechanism for adjusting the amount of discharge.

Note that the hydraulic oil is also used as lubricating oil in the transmission case, so the transmission case itself is the tank 9.
It is used for.

Next, to explain the operation, when the shovel device 4 is attached to the front as an attachment as shown in the figure, the tilling device 2 is installed as a rear balance weight, and with the control valve 8 in the neutral position. The control valve 12 is switched to operate the hydraulic cylinder 6.6 to carry out excavating work, and at this time the return oil flows through the valve 8.
The oil then returns to the tank 9 through the oil drain path C.

Further, when the control valve 8 is switched to the lift arm raising side with the hydraulic cylinder 6.6 in operation, if the load on the hydraulic cylinder 5 is large, the shovel device 4
The oil returned from the side returns to the tank 9 through the preliminary oil drain path g, and the hydraulic pump 7 is not overloaded.

Incidentally, since the pressure on the upper side of the variable throttle ridge 14 acts on the hydraulic cylinder 5, the lift arm 1 can be swung upward depending on the weight of the tilling device 2.

Further, for this purpose, it is preferable to set the amount of throttle of the variable throttle valve 14 in advance according to the type of work device to be attached to the lift arm 1.

However, it is necessary to adjust the load so that the load when the two hydraulic cylinders 5, 6.6 are operated does not exceed the allowable load of the pump 7.

Furthermore, when an attachment such as a shovel device is removed, the connecting portion 11 is short-circuited to form a hydraulic circuit consisting only of the hydraulic cylinder 5, and the tilling device 2 or other working device is raised and lowered by the lift arm 1.

In the embodiment, a variable throttle valve 14 was used as a valve mechanism for regulating the discharge amount interposed in the preliminary oil drain path g, but as shown in FIG. cylinder 6
．． It would be convenient to be able to select between a state where only the hydraulic cylinders 6 and 6 can be used, a state where the hydraulic cylinders 5 and 6.6 can be used, and a state where the hydraulic cylinders 5 and 6.6 can be used, and a state where the hydraulic cylinders 5 and 6.

[Brief explanation of the drawing]

The drawings show an embodiment of the tractor according to the present invention. Fig. 1 is an overall side view of the tractor equipped with a working device, Fig. 2 is a hydraulic circuit diagram showing the elevating drive mechanism, and Fig. 3 is a hydraulic circuit diagram showing the elevating drive mechanism. FIG. 7 is a hydraulic circuit diagram showing another embodiment of the valve mechanism. 5...Hydraulic cylinder, 6...Hydraulic actuator, 8...Control valve, 9...
・Tank, 10...Relief valve, 11...
... Connection part, 14 ... Valve mechanism for adjusting the discharge amount,
b...↓...Oil passage, f...Oil drain passage, g...
...Preliminary oil drain path.

Claims (1)

[Scope of claim for utility model registration] ■ Hydraulic cylinder 5 for driving the lift arm installed on the aircraft body
A connection part 11 is provided to connect the oil supply and discharge passage of the attachment driving hydraulic actuator 6 in series in the middle of the oil passage that supplies pressure oil to the control valve 8 of the hydraulic cylinder 5. In a tractor equipped with an IJ valve 10 in the middle of the pressure oil supply path of the hydraulic actuator 6, a preliminary oil drain path g communicating with the tank 9 is branched from the middle of the oil drain path f of the hydraulic actuator 6, and this preliminary oil drain is A tractor characterized in that a valve mechanism 14 for adjusting a discharge amount is interposed in an oil passage g. (2) The tractor according to claim (2), wherein the valve mechanism 14 for adjusting the exhaust flow rate is a throttle valve. (2) The tractor according to claim (2), wherein the valve mechanism 14 for adjusting the exhaust flow rate is a switching valve.