JPS5830865Y2 - Dozer work vehicle circuit - Google Patents

Description

[Detailed Description of the Invention] The present invention is a dozer in which the left and right traveling devices are configured to be driven by separate motors and pumps, and the motor and dozer lifting cylinder are connected in parallel to the first pump. Regarding circuits of work vehicles.

Conventionally, the dozer cylinder was operated by supplying pressure fluid from only one pump, and when the dozer cylinder was operated without running, the amount of fluid supplied to one drive motor was smaller than the other. However, there was a problem with it running diagonally.

In view of the above points, the purpose of the present invention is to solve the problem of skew when operating the dozer cylinder while the vehicle is not traveling, and also to solve various problems caused by the configuration for this purpose. .

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

A swivel base 2 is attached to a traveling vehicle body equipped with crawler traveling devices 1, 1.
is provided so as to be able to freely rotate around the vertical axis 4, a backhoe 3 is provided at the front of the swivel base 2, and a control unit 4 is provided, and on the other hand,
A dozer device 5 is provided on the traveling vehicle body, and the traveling devices 1, 1,
The swivel base 2 and both working devices 3 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 equipped with a work vehicle so that it can perform both ground excavation and earth removal work.

The left and right traveling devices 1, 1 each have separate traveling motors M1.
, M2 and pump P1. P2, and a travel control valve (1) for the first motor M1 and a dozer control valve (3) for a dozer cylinder 6 for driving and lowering the dozer device are connected in parallel to the first pump P1. On the other hand, a traveling control valve (2) for the second motor M2 and a confluence control valve (4) for supplying the pressure oil from the second pump P2 to the dozer cylinder 6 are connected in parallel to the second pump P2. be.

The merging control valve (4) is configured to be operable in conjunction with the dozer control valve (3), and the traveling control valve (2) for the second pump P2 controls the pressure oil to flow into the center bypass flow when it is in its neutral state. The pressure oil from the second pump P2 is combined and supplied to the dozer cylinder 6 only when the second motor M2 is driven, in other words, when the second motor M2 is running. When the second motor M2 is stopped, in other words when the vehicle is stopped, pressure oil is supplied to the dozer cylinder 6 only from the first pump P1.

In the middle of the merging supply path from the second pump P2 to the dozer cylinder 6, a check valve 7 is installed at a location on the upper side of the merging control valve V4 to prevent backflow from the dozer cylinder 6 side to the second pump P2 side. The interposed flow path portion and the flow path portion interposed with the crest valve 8 are connected in parallel, and when the second motor M2 is stopped (this, the dozer cylinder 6 is at the stroke end (this), The configuration L7 is configured such that when the pressure reaches the limit, the pressure oil from the first pump P1 is relieved through the stop valve 8 at a pressure lower than the set pressure of the relief valve R.

In summary, in the circuit of the dozer work vehicle described above, the present invention provides a merging supply path for the cylinder 6 for the 20th pump P2 in parallel with the motor M2 and substantially connects the motor M2 to the 20th pump P2. A merging control valve 4 is provided in the merging supply path and is connected to enable fluid supply only during driving and is operable in conjunction with the dozer control valve 3 provided in the flow path from the first pump P1. The said merging control valve ■4
In a part of the -E side, a flow path portion including a check valve 7 that prevents backflow from the cylinder 6 side to the second pump Pz side and a flow path portion including a throttle valve 8 are arranged in parallel. It is characterized by being connected.

In other words, since the dozer cylinder 6 is operated by jointly supplying pressure fluid from both pumps PLP2, when operating the dozer cylinder 6 without traveling,
Due to the operation of the dozer cylinder 6, it is possible to avoid a reduction in the amount of pressure fluid supplied to one of the traveling motors, and it has become possible to prevent skewing.

In addition, if pressure fluid is always supplied to the dozer cylinder 6 in a combined manner from both pumps P and P2, a large amount of pressure fluid is jointly supplied to the dozer cylinder 6 when not traveling, and the cylinder 6
There is a problem that the dozer device 5 operates at high speed, making it difficult to adjust the 4-unit lower position of the dozer device 5.
Such a problem can also be solved by making it possible to supply pressure fluid to the dozer cylinder 6 only from the dozer cylinder 6.

Furthermore, when a high load is applied to the dozer cylinder 6 during non-travelling, or when the stroke end is reached, the pressure acting on the dozer control valve (3) and the merging control valve (4) which is operated in conjunction with it increases. An unbalanced load is applied to both control valves V3.
．． Simultaneous switching of V4 requires a large operating force, which causes a problem in which the switching operation becomes difficult, but the merging control valve ■4
Since the throttle valve 8 is installed on the upper side of the dozer cylinder 6, the load on the dozer cylinder 6 increases, but the supply fluid
The pressure rise can be suppressed by relieving the pressure through the throttle valve 6, and such problems can be solved, and an excellent operability can be obtained.

[Brief explanation of the drawing]

The drawings illustrate an embodiment of the circuit of the dozer working vehicle according to the present invention, and FIG. 1 is an overall side view of the working vehicle, and FIG. 2 is a hydraulic circuit diagram. 1... Travel device, 6... Dozer cylinder, 7... Check valve, 8... Throttle valve, M
□, M2...Motor, Pl. P2...Pump, ■3...Dozer control valve, ■4...Merge control valve.

Claims (1)

[Scope of utility model registration request] The left and right traveling devices 1, 1 are configured to be driven by separate motors M1, M2 and pumps P□, P2, and the motor M1 and the dozer lifting cylinder 6 are connected in parallel to the first pump P1. In this circuit of the dozer work vehicle, a confluence supply path for the cylinder 6 is connected to the second pump P2 in parallel with the motor M2 so that fluid can be supplied substantially only when the motor M2 is driven, and A merging control valve 4 that can be operated in conjunction with the dozer control valve 3 provided in the flow path from the first pump P1 is provided in the merging supply path, and a merging control valve 4 on the upper side of the merging control valve 4 of the merging supply path is provided. In a part, the second pump P is connected from the cylinder 6 side.
a flow path portion equipped with a check valve 7 that prevents backflow to the second side;
A circuit for a dozer work vehicle, characterized in that a flow path section provided with a throttle valve 8 is connected in parallel.