JPS6219673Y2 - - Google Patents

Description

[Detailed description of the invention] This invention is equipped with a crane at the front of the vehicle and a double-acting hydraulic cylinder equipped with a ground plate at the rear of the vehicle. The present invention relates to a work vehicle in which the ground plate is extended and installed on the ground.

Today, power units have come to be used in various fields as a convenient hydraulic drive means.

This power unit consists of a tank, an electric motor,
a hydraulic pump driven by the electric motor;
It consists of a relief valve and a directional switching valve installed in the discharge oil path of a hydraulic pump. As for the directional control valve, there are known a 3-position directional control valve with a neutral position and a spring offset type 2-position directional control valve without a neutral position. It is widely used because it is relatively inexpensive. By the way, the power unit equipped with this spring offset type two-position directional control valve is used to drive the double-acting hydraulic cylinder of the work vehicle (this is to ensure safety performance during crane work). In the case where the spring offset type 2 position directional control valve is adopted for this purpose, the oil passage connecting the spring offset type 2 position directional control valve and the double acting type hydraulic cylinder is connected to the state where the spring offset type 2 position directional control valve is located at the offset position. When the hydraulic pump is driven, the double-acting hydraulic cylinder is driven to extend. Therefore, if the operator is inexperienced, the double-acting hydraulic cylinder will extend at the same time as the switch for driving the electric motor is operated, which is dangerous and may cause an unexpected accident.

In the above-mentioned work vehicle, the present invention provides that when the electric motor is driven via the switch and the spring offset type two-position directional control valve is in the offset position, the oil discharged from the hydraulic pump is transferred to the double-acting type. When the spring offset two-position directional control valve is in a non-offset position, the oil discharged from the hydraulic pump is supplied to the side that drives the double-acting hydraulic cylinder to extend. The double-acting hydraulic cylinder and the spring offset type 2-position directional switching valve are connected via an oil passage, and with this configuration, the switch and the spring offset type 2-position directional switching valve are connected via an oil passage. It is safe because the double-acting hydraulic cylinder is driven to extend only when both valves are operated.

Next, the present invention will be explained in detail based on one specific example.

In FIG. 1, A is a working vehicle, and a crane B is mounted just behind the driver's cab. This crane B is equipped with a telescoping boom 1, a hoisting cylinder 2 that controls the elevating of the telescoping boom 1, and outriggers 3 that raise the vehicle body until the front wheels of the vehicle are lifted up after the vehicle is extended outward on both sides. This is an operating lever that controls the operation of the telescopic boom 1, the hoisting cylinder 2, the outrigger 3, etc. The valves operated by these are operated by the engine power PTO
Discharge oil from a hydraulic pump is supplied via the device.

In FIG. 2, C is a power unit installed in the working vehicle, and this power unit C
The hydraulic pump 7 includes an electric motor 6, a hydraulic pump 7 pivotally connected to the electric motor 6, a tank 8, a spring offset type two-position directional switching valve 9, a relief valve 10, and the like.

In Figures 1 and 2, reference numeral 5 denotes a double-acting hydraulic cylinder, which is located behind the rear wheels of the vehicle, and when the cylinder is extended and driven, a ground plate 5' provided at its lower end is installed on the ground, allowing it to be used during crane work. This contributes to ensuring the stability of work vehicles. In the spring offset type two-position directional control valve 9, in its offset position, the A port communicates with the contraction side pressure oil chamber of the double-acting hydraulic cylinder 5 via the oil supply/drain passage 11, and the B port communicates with the pressure oil chamber on the reduction operation side of the double-acting hydraulic cylinder 5. It communicates with the extension side pressure oil chamber of the double-acting hydraulic cylinder 5 through the oil passage 12, and when oil is discharged from the hydraulic pump 7 in this state, the double-acting hydraulic cylinder 5 is connected to the contracting side, that is, the double-acting hydraulic cylinder 5. Discharge oil is supplied to the storage side of the dynamic hydraulic cylinder 5, and when the operator performs a switching operation from the offset position via the operating lever 13, the hydraulic pump 7 is connected to the oil supply and discharge path 12, and the oil supply and discharge is performed. Oil road 1
1 is connected to the tank 8, when oil is discharged from the hydraulic pump 7, the discharged oil is directed to the side where the double-acting hydraulic cylinder 5 extends, that is, to the non-storage side of the double-acting hydraulic cylinder 5. It is supplied. 1
4 is a pilot type check valve inserted in the oil supply/drainage path 12, and is used to drain oil from the extension side pressure oil chamber of the double-acting hydraulic cylinder 5 during crane work with the ground plate 5' installed on the ground. It has a blocking effect. Reference numeral 15 denotes a pilot check valve inserted in the oil supply and discharge passage 11, which prevents the piston rod of the double acting hydraulic cylinder 5 from moving downward under its own weight. 16 is a battery, and a switch 17 is inserted in the electric circuit between the battery 16 and the electric motor 6. And this switch 17
When turned ON, the electric motor 6 is driven.

Next, the action will be explained.

When the operator turns on the switch 17 to start work, the spring offset type 2
Since the position and direction switching valve 9 is in the state shown in FIG. 5 is supplied to the reduction operation side pressure oil chamber. At this time, if the piston of the double-acting hydraulic cylinder 5 is in the most compressed state at the end of its stroke, the contraction movement of the double-acting hydraulic cylinder 5 does not occur, and the discharged oil is returned to the tank 8 via the relief valve 10. do. Next, when the operator operates the operating lever 13 to switch the spring offset type two-position directional switching valve 9, the oil discharged from the hydraulic pump 7 passes through the oil supply and discharge path 12 to the double-acting hydraulic cylinder 5.
The oil in the contraction side pressure oil chamber of the double-acting hydraulic cylinder 5 is supplied to the extension side pressure oil chamber of the double-acting hydraulic cylinder 5 and returns to the tank 8 via the oil supply/discharge path 11. do. When the extension is completed, the switch 17 is turned OFF to stop driving the electric motor 6, and then the operation of the operating lever 13 is stopped to position the spring offset type two-position directional control valve 9 to the offset position.

In this way, the switch 17 for driving the electric motor 6
The double-acting hydraulic cylinder will not extend just by turning ON, and the double-acting hydraulic cylinder will not operate against the operator's will.

Note that it is possible to save time by operating the double-acting hydraulic cylinder 5 to the retracting side at the same time as the operation for retracting the outriggers 3, so as shown in FIG. A switch 18 is installed in parallel with switch 17 in the link mechanism that transmits the lever movement to the valve.
An actuator for ON/OFF control may be provided.

[Brief explanation of the drawing]

FIG. 1 is a side view of a working vehicle showing an embodiment of the present invention, and FIG. 2 is a circuit diagram thereof. A: Work vehicle, B: Crane, 5': Ground plate,
5; Double acting hydraulic cylinder, 8; Tank, 6; Electric motor, C; Power unit, 17; Switch,
9; Spring offset type 2-position directional valve;
7; Hydraulic pump.

Claims (1)

[Scope of claim for utility model registration] A crane is provided at the front of the vehicle, and a double-acting hydraulic cylinder equipped with a ground plate is provided at the rear of the vehicle, and the double-acting hydraulic cylinder is extended during crane work. The work vehicle in which the ground plate is installed on the ground includes a tank, an electric motor, a hydraulic pump driven by the electric motor, a relief valve provided in a discharge oil path of the hydraulic pump, and a spring offset type 2. When a power unit including a position-direction switching valve is disposed, the electric motor is connected to a battery provided in the vehicle via a switch, and the electric motor is driven via the switch, the spring offset type When the two-position directional control valve is in the offset position, the discharge oil of the hydraulic pump is supplied to the side that drives the double-acting hydraulic cylinder for contraction, and when the spring offset two-position directional control valve is in the non-offset position, the The double-acting hydraulic cylinder and the spring offset type two-position directional switching valve are connected via an oil path so that discharge oil from the hydraulic pump is supplied to the side that drives the double-acting hydraulic cylinder to extend. Characteristic work vehicle.