JPH03157275A - Hydraulic type running drive device for working vehicle - Google Patents

Abstract

PURPOSE:To improve straight running ability and drivability by a method wherein a rotation direction is shifted by a running control valve to control the feed and discharge of pressure oil to and from a pair of hydraulic motors for an uneven terrain type running devices on both sides, and a delivery amount of d variable volume type hydraulic pump is varied and an equivalent branch feed is effected by a flow divider. CONSTITUTION:A hydraulic motor M1 is linked to a crawler drive wheel 5a of each of crawler running devices 5 on both sides of a crawler type running device body, e.g. a radio controllable reel type lawn mower. A pair of running control valves (three position switching valve) V1 mounted to respective hydraulic motors M1 through respective feed discharge oil passages 8 are connected to the delivery side of a variable volume type first hydraulic pump P1 through a feed oil passage 8, in which a flow divider 7 is located, and connected to the suction side of the first hydraulic pump P1 through a return oil passage 9. The flow divider 7 branches oil, inputted through an input port 7a, into two equivalent amounts of branch oil, and each branch oil is feedable through each output port 7b to running control valves V1 and V2.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention provides a hydraulic system for a work vehicle that is provided with an uneven terrain type left and right traveling device and configured such that each of the left and right traveling devices is driven separately by a pair of hydraulic motors. The present invention relates to a type traveling drive device.

[Conventional technology]

As shown in Fig. 4, the above-mentioned work vehicle conventionally consists of a variable displacement expansion hydraulic pump (P) and a hydraulic motor (M1), and moves forward across the neutral position by operating the swash plate angle of the hydraulic pump (P). A hydraulic continuously variable transmission (H3T) that can switch between side and reverse is attached to each of the left and right travel devices (5) and (5), and the engine (E) is accelerated for work travel, etc. It is now possible to change the traveling speed steplessly even when the vehicle is in the set state, and it is also possible to make pivot turns by driving one of the left and right traveling devices forward and the other in reverse. There was something.

[Problem to be solved by the invention]

Conventionally, due to manufacturing errors between the left-hand continuously variable transmission and the useful continuously variable transmission, a drive speed difference between the left and right traveling devices has occurred, and straight-line performance has tended to deteriorate.

It is an object of the present invention to provide a drive system that can provide continuous speed change when the engine accelerator is set, and can also perform pivot turns while providing straight-line performance at a relatively low cost.

[Means to solve the problem]

In the hydraulic traveling drive device for a work vehicle according to the present invention,
In order to achieve this purpose, a pair of hydraulic motors that separately drive the left and right traveling devices of the rough terrain type are each equipped with a travel control valve that can be freely switched between forward and reverse directions, and the inflow oil is divided between one of the travel control valves and the other. One variable displacement hydraulic pump is connected to each of the travel control valves via a flow divider that divides and supplies equal amounts of water to the travel control valves. And its effect,
And the effects are as follows.

[For production]

When both of the left and right travel control valves are switched to the drive position, one of the divided flow parts supplied from the hydraulic pump to the flow divider is supplied to one hydraulic motor, and the other flow control valve is supplied to the other hydraulic motor. Furthermore, one branch part and the other branch part are supplied in equal amounts, and both of the left and right hydraulic motors are driven at the same or approximately the same rotational speed. Therefore, if both the left and right travel control valves are on the forward rotation side or the reverse rotation side, both the left and right travel devices are driven in the forward or reverse direction, and the drive speeds of the left and right travel devices are equal or almost equal. The aircraft moves straight or almost straight in the forward or reverse direction.

When one of the left and right travel control valves is on the forward rotation side and the other is on the reverse rotation side, one of the left and right travel control devices is driven to the forward movement side and the other to the reverse movement side, and the aircraft makes a pivot turn. Furthermore, even if the engine is in the accelerator set state, the discharge amount of the variable displacement hydraulic pump changes steplessly and the motor speed changes steplessly, so the traveling speed changes steplessly.

〔Effect of the invention〕

The variable displacement hydraulic pump's discharge amount can be changed, the flow divider can supply an equal amount of divided flow, and the travel control valve can change the rotation direction, allowing for continuously variable speed travel and pivot turning, making work more efficient. However, it was designed to have relatively good straight-line performance and be easy to maneuver. Furthermore, it was possible to achieve an economical advantage by providing only one variable displacement pump as a hydraulic pump, and one that could discharge in only one direction.

〔Example〕

Next, examples will be shown.

As shown in Figure 3, a reel-type machine is installed at the front of a crawler-type traveling body with an engine (E) at the rear of the body, which can be raised and lowered via a link mechanism (1) that is raised and lowered by a lift cylinder (C). While connecting the lawn mowing device (2),
The traveling aircraft is equipped with a controller (4) that receives operation signals from a control device (not shown) through an antenna (3) and automatically performs travel and work control based on the input signals, and radio control is performed. This is a reel-type lawn mower that is capable of

The first to third hydraulic pumps (PI) and (P2) are installed on the traveling aircraft to enable the aircraft to travel and drive the lawn mower.
.

(P3) is constructed and provided so as to be driven by an engine (E), and a hydraulic drive device is constructed as shown in FIG.

In other words, a hydraulic motor (M1) is linked to the crawler drive wheels (5a) of the left and right crawler type traveling devices (5), (5), and supply and discharge are carried out separately to the pair of hydraulic motors (M1), (M1). A pair of travel control valves (
V1), (V1) is connected to an oil supply path (8) having a flow divider (7).
) to the discharge side of the first hydraulic pump (P1), and
They are respectively connected to the suction side of the first hydraulic pump (P1) via return oil passages (9). Then, the first hydraulic pump (P
+) is configured as a variable displacement pump, and the flow divider (7) divides the oil flowing in from the input port (7a) into two equal volume divided parts, and one divided part is connected to one output port (7b). from the other output port (7b) to one travel control valve (V1), and from the other output port (7b) to the other travel control valve (V1).
The two travel control valves (V1
), (V, ) are configured as three-position switching valves so that the hydraulic motor (M1) can be operated in neutral and reversed. In other words, one of the two equal amount of divided flow parts supplied from the first hydraulic pump (P1) to the flow divider (7) is connected to one hydraulic motor (M1), and the other flow divided part is connected to the other hydraulic motor (M1). A pair of oil motors (M1) that respectively supply oil to the hydraulic motors (M1) and rotate for this oil supply.

(M1) to drive the left and right traveling devices (5), (5) separately. Then, one travel control valve (
The left and right travel device (5 ) and (5) to the forward or reverse side to make the aircraft go straight, or drive one of the left and right traveling devices (5) and (5) to the forward side and the other to the reverse side to move the aircraft. The left and right hydraulic morph (M1) is made by turning the pivot and changing the discharge amount of the first hydraulic pump (P1).

(M1) The drive rotational speed of both of them is changed steplessly to change the traveling speed steplessly.

The oil supply path (8) and the return oil path (9) are configured to supply oil to the second hydraulic pump (P2) via the charge oil path (10).
) is connected to.

A power take-off shaft (11) that transmits rotational force to the lawn mower (2)
) is linked to the hydraulic motor (M2), and the control valve (V2) of this hydraulic motor (M2) is linked to the third hydraulic pump (P
3), and is configured to stop the hydraulic motor (M2) by switching the control valve (V2) and to switch between forward and reverse rotations to stop and drive the lawn mower (2) and change the direction of rotation. be.

The engine (E) is equipped with a start restriction means that automatically operates at zero based on the flowchart shown in Figure 2 to prevent troubles such as the machine running out of control or the lawn mower (2) operating at the same time as the engine starts. This is the aim. That is, it detects whether the control mode is in radio control mode or manual mode, detects whether the first hydraulic pump (P1) is in a neutral operating state, and detects whether the power take-off shaft (11) is in a stopped operating state. , the control mode is in manual mode, the first hydraulic pump (P1) is in a neutral operation state, and furthermore, the power take-off shaft (11) is in a stop operation state. Only then is an engine start check device (not shown) released to allow the engine to start.

The present invention can also be applied when the left and right crawler type traveling devices (5), (5) are changed to a multi-wheel type in which a plurality of wheels are arranged in the longitudinal direction of the aircraft body. Therefore, these are referred to as rough terrain type traveling devices (5).

It can also be used as a work vehicle for various tasks other than lawn mowing, and can also be applied to passenger vehicles.

Incidentally, although reference numerals are written in the claims section for convenient comparison with the drawings, the present invention is not limited to the structure shown in the accompanying drawings.

[Brief explanation of the drawing]

The drawings show an embodiment of the hydraulic travel drive device for a working vehicle according to the present invention, with Fig. 1 being a hydraulic circuit diagram, Fig. 2 being a flowchart for engine start restriction, and Fig. 3 being a side view of the entire lawn mower. be. FIG. 4 is a schematic diagram of a conventional travel drive device. (5)... Traveling device, (7)... Divider, (P1)... Variable displacement hydraulic pump, (V
, )... Travel control valve, (M1)... Hydraulic motor.

Claims (1)

[Claims] A pair of hydraulic motors (M_1), (M_1) that separately drive the rough terrain type left and right travel devices (5), (5) are each equipped with a travel control valve (V_1) that can be freely switched between forward and reverse directions, and the inflow oil 1 to both of the travel control valves (V_1) through a flow divider (7) that divides and supplies equal amounts to one of the travel control valves (V_1) and the other travel control valve (V_1). A hydraulic travel drive system for a work vehicle to which two variable displacement hydraulic pumps (P_1) are connected.