JPS6053472A - Four-wheel-driven agricultural tractor - Google Patents

Abstract

PURPOSE:To improve the machine body turning operability at a small radius by providing a front wheel acceleration mechanism increasing the rotating speed of front wheels concurrently with the steering operation of the left and the right front wheels as the steering angle of the front wheels is increased. CONSTITUTION:In a tractor having the left and the right front wheels 1, 1' steerable by a power steering mechanism 5 and the left and the right rear wheels 2, 2', the rear wheels 2, 2' are driven by the power of a reduction unit 10 connected to an engine 17 via a differential mechanism 11. In addition, the front wheels 1, 1' are driven by the power branched from a transmission mechanism between the reduction unit 10 and the differential mechanism 11 via an acceleration mechanism 13 and a differential mechanism 12. In this case, the acceleration mechanism 13 is made a stepless speed changer and controls a speed changing actuator 13A so as to increase the rotating speed of the front wheels 1, 1' as the steering angle is increased when a brake mechanism 8 or 8' individually braking the rear wheels 2, 2' is operated by the operation of a steering handle 4.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a four-wheel drive agricultural tractor, and more specifically, the rotational speed of the front drive wheels when the machine turns is increased compared to that when traveling straight, thereby reducing the radius of the machine. It relates to something that is configured so that it can be turned.

Conventional four-wheel drive agricultural tractors of this type have been equipped with a speed increasing mechanism that can manually switch the rotational speed of the front drive wheels between increased speed and normal speed. When turning the aircraft, it is necessary to increase the speed in addition to steering the nose wheels, which not only has poor operability, but also increases the rotation speed of the nose wheels regardless of the size of the steering angle of the nose wheels. Since the speed is uniformly increased, there are drawbacks such as the aircraft's turning performance is not smooth due to increased speed, and it may also be dangerous.

The present invention has an object to overcome such conventional drawbacks.

The characteristic structure of the four-wheel drive agricultural tractor according to the present invention taken to achieve the above object is as follows:
In addition, the present invention has a front wheel speed increasing mechanism that increases the rotational speed as the steering angle of the front wheels increases. be.

Since the front wheel speed increasing mechanism automatically switches to the speed increasing side in conjunction with the steering operation of the front wheels, there is no need for manual operation to speed up the front wheels when the aircraft turns. In addition, the front wheel speed increasing mechanism changes the rotational speed of the front wheels so that the larger the steering angle of the front wheels becomes, the higher the rotational speed is. The smaller the turning radius, the faster the rotation speed of the front wheels becomes.
The rotational speed of the front wheels can be adjusted according to the turning radius.

Therefore, the present invention has the effect of increasing the rotational speed of the front wheels to improve the maneuverability of the aircraft in a small radius, and also allows the aircraft to turn smoothly regardless of the size of the turning radius. I was able to play it.

Embodiments of the present invention will be described below based on the drawings.

A pair of steerable left and right driving front wheels Q) t (1!l, and a pair of left and right driving rear wheels (2) + ('to, the front wheels (1).

In a four-wheel drive agricultural tractor equipped with a power steering mechanism for the front wheels (1'l) and a mechanism capable of braking the rear wheels (2) and (2'l) separately,
) + (In conjunction with the steering operation of a, the front wheel (1)
+ (1'l0 A front wheel speed increaser f#(3) is provided that changes the rotation speed so that the closer the steering angle is, the faster the rotation speed becomes.

The power steering mechanism includes a sensor (Sl) using a potentiometer/meter that detects the steering angle of the steering handle (4), and a sensor (Sl) using a potentiometer that detects the steering angle of the front wheels (u), (1). (S2), the hydraulic cylinder (5) that drives and steers the front vehicle! (1), (15), and the detection result of the steering angle detection sensor (S2) is the detection result of the steering angle detection sensor (Sl). and a control circuit (7) for controlling the control pulp (6) of the hydraulic cylinder (5) so as to match the above-mentioned hydraulic cylinder (5).

The braking mechanism includes a pair of left and right brakes (8) l (s) capable of braking the rear wheels (1) l (15) separately, and a pair of left and right pedals (9) for operating these separately.
).

(It consists of nine items.

The front wheel speed increasing mechanism (3) is a continuously variable transmission interposed in the transmission system to the front wheel differential mechanism (6) which is branched from the transmission system from the transmission tIQ to the rear wheel differential mechanism Vυ. (to), the pedal (9), (sensor switch (Ss) that detects the current braking operation, (83, and the sensor switch (Ss) that detects the rise of the lift arm (1'J) that raises and lowers the working device 14). S4) and a sensor switch (SS) that detects the shift operation of the shift operation lever (IOA) to the working speed.
and the braking detection sensor switch (Sa).

(The steering angle detection sensor (S2) in the power steering mechanism detects only when only one of the sensor switches (S4) and (SS) detects the presence. Based on the results, a control circuit uQ is provided to operate the actuator (13A) (hydraulic cylinder, etc.) of the continuously variable transmission device μ to change the speed, thereby continuously changing the rotational speed of the front wheels (IJ, (15). It is configured.

(17) is the engine, and (f) is the clutch.

According to the configuration of the above embodiment, when the aircraft direction is performed only by operating the steering wheel (4) while driving on the road, the speed of the front wheels (i) + (15) is not increased and the aircraft direction is normally performed. You can use the handle (
4) and brake the one-side wheel (2 or 2') to make the aircraft turn, the front wheel (1),
<1'> is increased as the steering angle increases, and the aircraft can turn smoothly with a small radius.

Note that the front wheel speed increasing mechanism (3) may be one that changes the speed in stages.

Also, when increasing speed, front wheels (1) + (19
The rear wheel (2), (2) minute speed in the direction of travel is the rear wheel (2).

(The speed may be increased so that it becomes equal to the speed of 2J, and the speed of the front wheel (1) l (1') becomes the rear wheel (2) l
(The speed of 25 may also be increased so that it is slightly faster or slower.

[Brief explanation of the drawing]

The drawings show an embodiment of a four-wheel drive agricultural tractor according to the present invention, with FIG. 1 being a side view, FIG. 2 being an operation and transmission system diagram, and FIG. 3 being a control circuit diagram. ...Drive front wheel, (3)...
...Front wheel speed increase mechanism.

Claims (1)

[Scope of Claims] ■ A pair of left and right drive front wheels (19) that can be freely steered to rotate the front wheels (1) and (1'l) at a rotational speed of 1'l. IJ +, (15) A four-wheel drive agricultural tractor that is provided with a front wheel speed increasing mechanism (3) that changes the rotation speed so that it increases as the steering angle increases. ■ The front wheel speed increasing mechanism ( 3) is a four-wheel drive agricultural tractor according to claim 0, in which the rotational speed is continuously changed. ■ A pair of left and right rear driven wheels (2J + t2) can be braked separately. A four-wheel drive agricultural tractor according to claim 0 or 2, which is a four-wheel drive agricultural tractor.