JPS5842393B2 - self-propelled car - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a first state in which fluid pressure motors for driving left and right traveling devices separately are driven by separate pumps, and integrally driven by combined fluid from these pumps. The present invention relates to a self-propelled vehicle equipped with a shift valve for switching to a second state, and more particularly to a self-propelled vehicle capable of appropriately and automatically switching drive states depending on driving conditions.

Japanese Utility Model Application Publication No. 50-39923 discloses a technique for automatically switching the driving state as described above.

However, this structure uses a mechanical mechanism that rotates unsteadily to change the shift valve, so it is difficult to assemble it to the aircraft, and it also requires hydraulic pressure. Since it uses a mechanical mechanism that is different from the structure, it has the disadvantage of being expensive.

Furthermore, in this structure, a throttle valve is provided in the circuit to the tank that relieves the pilot pressure, so when the shift valve returns to its original state against the IJ-F pressure, the action of the throttle valve is The disadvantage was that there was a delay.

The present invention aims to eliminate the above-mentioned drawbacks.

Next, embodiments of the present invention will be described in detail based on illustrative drawings.

A swivel base 2 is mounted on a traveling machine base equipped with crawler traveling devices 1 and 1.
is provided so as to be able to rotate freely around the vertical axis 2, and the control unit 3 is mounted on the swivel base 2.
and an excavation device 4 is provided in the front part thereof, and an earth removal device 5 is provided on the traveling machine base, and the said traveling devices 1, 1,
The swivel base 2 and both working devices 4 and 5 are configured to be driven by hydraulic pressure, which is an example of a fluid pressure type.
Although it is a stand, it is a self-propelled work vehicle that can perform both ground excavation and earth removal work.

To drive the left and right crawler traveling devices 1, 1, two hydraulic pumps P1. The pressure oil from P2 is transferred to the control valve ■1. By the switching operation (2), the hydraulic motors are supplied to the first and second hydraulic motors M1 and M2 for traveling through the rotary joint 6, and are hydraulically driven in the forward and reverse directions.

As shown in FIG. 2, both the pumps P1. In the middle of the pressure oil supply path from P2, the control valve v1. On the upper side of each V2,
A speed change valve 7 is provided, and by switching the speed change valve 7, a first state in which the first and second oil motors M12M2 are respectively driven by the first pump P1 and the second pump P2, respectively; Pump P1. The pressure oil from P2 is combined, and the combined pressure oil is transferred from the first motor M1 to the second motor M.
It is configured so that it can be switched to a second state in which it is supplied to the motors 2 and 2 and driven integrally.

A branch flow path 9 is connected to each of the pressure oil flow paths to the first motor M1 and the second motor M2 through a one-way valve 8.
At the same time, this branch flow path 9 is interlocked and connected to the speed change valve 7 via a pilot pressure mechanism 10, and the speed change valve 7 is removed in accordance with the load on both motors M12M2, that is, the running load. For example, when the supply pressure to the motor M12M2 increases in the second drive state, the speed change valve 7 is automatically switched to the first drive state. It is configured to be automatically and reversibly switched.

As shown in FIG. 3, the pilot pressure mechanism 10 is constructed by applying pilot pressure to one side of the balance valve 12, which has a valve body 12 biased toward the closing side via a compression spring 11. The branch flow path 9 is connected in communication, and the IJ IJ-F circuit 14 is connected in communication with the other downstream side, and the branch flow path 9 and the IJ IJ-F circuit 14 are balanced with the speed change valve 7. Valve 1
It is connected to the body 15 of No. 3 through communication ports 16 and 17 formed therein.

The longitudinal length of the valve body 12 corresponds to the length between the two-speed communication ports 16 and 17, and the communication port 17 communicating with the relief circuit 14 is configured to be closable by the piston portion 18 of the valve body 12. When the balance valve 13 is opened against the urging force of the compression spring 11 as the supply pressure to the first motor M1 and the second motor M2 increases, the IJ-IJ-flow circuit 14 is closed, Pilot pressure is applied to the speed change valve 7 to switch from the second driving state to the first driving state, and in this switching state, the motor M12M2
The balance valve 13 is closed so that the hydraulic oil supplied to the motors does not flow through the IJ IJ circuit 14, and on the other hand, when the supply pressure to both motors M12M2 becomes lower than the set value due to switching, the balance valve 13 is closed. At the same time, the IJ-IJ-F circuit 14 is opened only in the closed state, and the shift valve 7 is switched from the first drive state to the second drive state by the biasing force of the return spring 19. .

A stopper 2 adjacent to the communication port 17 prevents the valve body 12 from moving toward the IJ IJ-F circuit 14 closing side.
0, and is configured to maintain the closed state of the relief circuit 14 by the balance valve 13 only when a pilot pressure higher than the set value is applied.

Note that the present invention is not limited to the type of work vehicle as in the above-mentioned embodiment, but is also applicable to the left-right running motor M12M2 which can be switched between the above-mentioned first state and second state by switching the speed change valve 7. If so, it can be applied to various types of self-propelled vehicles.

In summary, the present invention provides a pilot pressure for automatically and reversibly operating the shift valve 7 to enter the first driving state as the supply pressure to the motor M12M2 increases in the officially registered self-propelled vehicle. A mechanism 10 is provided, and in the pilot pressure mechanism (2), the motor M12M2
The IJ-flow circuit 14 from the downstream side of the balance valve 13, which is automatically and reversibly opened as the supply pressure increases, is configured to be opened only when the balance valve 13 is closed. It is characterized by

In other words, as the running load increases, the second drive state is automatically switched to the first drive state, and the running can be performed continuously and satisfactorily in accordance with the running load. Only when switching to the second drive state, the relief circuit 14 is opened to ensure that the shift valve 7 is switched back, and the balance valve 13 is opened to switch from the second drive state to the first drive state. Occasionally, the relief circuit 14 is closed, and the supply fluid to the motor M19M2 is drained through the relief circuit 14 due to the pilot pressure take-off, thereby reliably avoiding a reduction in running torque, and responding to an increase in running load. It has now become possible to reliably run the vehicle in the first drive state.

In this way, since the shift valve 7 is switched via the balance valve 13, unlike the conventional structure described at the beginning, which uses a mechanical mechanism that rotates for unstable switching, Installation on the aircraft is not complicated and can be easily assembled, and there is no need to install a throttle valve to apply constant pressure to a mechanical mechanism that rotates unstably. The valve can be restored quickly, and by omitting the throttle valve, it can be constructed at low cost.

[Brief explanation of the drawing]

The drawings show an embodiment of a self-propelled vehicle according to the present invention; FIG. 1 is an overall side view of the working vehicle, FIG. 2 is a hydraulic circuit diagram for driving the vehicle, and FIG. 3 is a longitudinal sectional view showing a pilot pressure mechanism. be. 1... Traveling device, 7... Speed change valve, 10... Pilot pressure mechanism, 13...
・Balance valve, 14...Relief circuit, P
l, P2...Pump, M18M2...
motor.

Claims (1)

[Claims] 1. The fluid pressure motors M12M2 for driving the left and right traveling devices 1, 1 separately are connected to separate pumps P1. A first state in which pumps P2 are driven, and those pumps P1. The self-propelled vehicle is provided with a speed change valve 7 for switching to a second state in which the motor M12M is integrally driven by the combined fluid from the motor M12M.
A pilot pressure mechanism 10 is provided for automatically and reversibly operating the speed change valve 7 to bring it into the first drive state as the supply pressure to the motor M12M2 increases, and the pilot pressure mechanism 10 controls the motor M12M2. The IJ-F circuit 14 from the downstream side of the balance valve 13, which is automatically and reversibly opened as the supply pressure increases, is configured to be opened only when the balance valve 13 is closed. A self-propelled car.