JPH0616149A - Turning control device for tractor - Google Patents

Abstract

PURPOSE:To attain turning with a small turning radius by constituting in such a way that when a front wheel steering angle is operated by equal to or more than a prescribed angle, a high speed and low speed switching device is switched to high speed, and a turning-inside rear wheel brake device is operated simultaneously. CONSTITUTION:In a front wheel clutch 10, low speed and high speed movement receiving plates 15 and 16 and low speed and high speed clutch gears 20 and 23 are arranged on a clutch shaft 10, and front wheel driving is constituted to be switched to low speed or high speed. Within a steering angle setting angle detected by a steering sensor, the front wheel clutch 10 is kept in neutral, and a tractor travels only by driving rear wheels, and within constant range where a steering angle is equal to or larger than that, the front wheel clutch 10 is thrown in low speed. When the steering angle becomes equal to or larger than a prescribed angle, the front wheel clutch 10 is switched automatically to high speed, and a turning-inside brake device 37 is operated simultaneously, and a brake is applied to a turning inside rear wheel, so that turning can be attained with a small turning radius without requiring complicated operation.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a turning control device for a tractor.

[0002]

2. Description of the Related Art In recent years, a high / low speed switching device has been incorporated in a front wheel drive system of a tractor so that the peripheral speeds of front and rear wheels are substantially equal when traveling straight, and the peripheral speed of a front wheel is substantially smaller than that of a rear wheel when turning. It is known that the speed is increased by about twice to create a high speed state. In the tractor and the like, brake devices for braking the rear wheels are provided independently on the left and right, and these are operated by operating a pair of left and right brake pedals provided at the foot of the driver. At the same time
Alternatively, they can be individually braked.

The left and right brake pedals are not connected except for traveling on the road which moves at a high speed. During general plowing work, the rear wheels on the inside of the turn are braked to turn the machine body with a small turning radius.

[0004]

When a tractor having a high / low speed switching device is used for cultivating work or the like, and if it is desired to turn the body with a minimum turning radius, the front wheel drive system is set to a high speed state. In addition, the brake device on the inside of the turn must be depressed to operate the brake device.This operation is complicated because the steering handle operation and the hydraulic lever operation are performed when turning at the field end. Further, it is also a burden on the driver to keep turning the brake pedal to turn when turning at the edge of the ridge.

[0005]

The present invention has been proposed in order to solve the above-mentioned inconvenience, and has taken the following technical means. That is, a high / low speed switching device that switches the driving state of the front wheels to high / low speed, a pair of left and right brake devices that independently brake the left and right rear wheels, and a steering angle detection device that detects the steering angle of the front wheels. In a tractor having
When the steering angle detecting device detects that the steering angle of the front wheels has been operated to a predetermined angle or more, the control means switches the high / low speed switching device to the high speed side and brakes the braking device of the rear wheel on the inside of the turn. The structure of the tractor turning control device is characterized in that

[0006]

Embodiments of the present invention will be described below based on the embodiments shown in the drawings. First, the structure will be explained as follows.
Is a tractor. The engine 2 is mounted on the front part of the machine frame, and the bevel gear of the rear wheel differential device 6 is attached to the rear end of the transmission shaft 5 that is mounted in the transmission case 3 and is mounted in the rearward direction. A bevel pinion 8 meshing with 7 is attached. And the clutch of the front wheel drive system (hereinafter referred to as the front wheel clutch)
A pair of transmission gears 11 and 12 having different numbers of teeth for transmission to 10 are attached.

A two-stage variable speed wet type multi-plate clutch is used as the front wheel clutch 10, and a clutch shaft 14 parallel to the transmission shaft 5 is provided with a low-speed passive plate 15, ..., And a high-speed passive plate 16 on both sides. , A receiving plate 18 having a driving plate 19 corresponding to the low speed passive plate 15, a low speed clutch gear 20 having a driving plate 19, and a driving plate 22 corresponding to the high speed passive plate 16. A high-speed clutch gear 23 including ... Is provided.

The clutch gears 20 and 23 are the clutch shaft 14
Is rotatable with respect to each of the transmission gears 11, 1
2 meshes separately. The front wheel clutch 10 includes a transmission gear 1 that includes a hydraulic switching valve 25 and a pressure control valve 26.
1 and the clutch gear 20 mesh with each other at a low speed, the transmission gear 12 and the clutch gear 23 mesh with each other at a high speed, and both are disengaged into three stages.

The clutch shaft 14 has a joint 28.
Drive shaft 3 that transmits rotational power to the front wheels via the
It is connected to 0. The shaft 32 (L, L of the rear wheel differential device 6
R) has a wheel pinion 35 (L, R) which meshes with the wheel gears 33 (L, R) of the left and right rear wheels, and a brake plate 38 (L) of the brake device 37 (L, R). , R) are attached. The brakes 39 (L, R) can be individually driven by the brake cylinders 42 (L, R) operated by the control of the switching valve 40 and the pressure control valve 41, and any side can be driven as necessary. The rear wheel can be braked.

The tractor-1 is provided with a steering control device 44 for controlling the steering of the traveling device. The steering control device 44 is configured as shown in FIG. 3, and the steering sensor 47 provided below the intermediate shaft 46 connected to the steering shaft 45 detects the steering angle of the front wheels, that is, the steering angle. This is processed by the controller 50, and an output signal is output to the switching valve 40 and the pressure control valve 41.

Explaining FIG. 4 concretely, A and B are rotation centers at the time of a weak turn and a sharp turn respectively, and C and D are the center points of the rear axle and the front axle, respectively, and the angles θ1, θ2, θ3.
Is a set angle that serves as a reference for control. When the detected steering angle detected by the steering sensor 47 is within the range of θ1, the front wheel clutch 10 is held neutral and only the rear wheels are driven to run. When the detected steering angle is within the range of θ1 to θ2, the clutch 10 is engaged at a low speed. The rotation ratio between the front and rear wheels at this time is R1: R
At 2, the front wheels rotate slightly faster than the rear wheels.

When the detected steering angle is in the range of θ2 to θ3, the front wheel clutch 10 is switched at high speed.
At this time, the rotation ratio of the front wheels to the rear wheels is R3: R4, and the front wheels rotate considerably faster than the rear wheels, so that the rear wheels do not slip even when making a sharp turn, and stable running is performed. You can Further, θ3 is a steering angle at the time of turning with the minimum turning radius, and when the detected steering angle approaches this, the brake device on the inside of the turn is activated to apply a brake on that side to assist a sharp turn. It has become. In this case, since the front wheel clutch 10 is switched to the high speed side, the front wheels do not become braked with respect to the rear wheels, and the vehicle can swiftly turn.

[0013]

As described above, the present invention has a high / low speed switching device for switching the driving state of the front wheels to high / low speed, a pair of left and right brake devices for independently braking the left and right rear wheels, and steering of the front wheels. In a tractor having a steering angle detecting device for detecting an angle, when the steering angle detecting device detects that the steering angle of the front wheels has been operated at a predetermined angle or more, the high / low speed switching device is switched to the high speed side. Since the control means for braking the brake device for the rear wheel on the inside of the turn is provided, when the driver makes a large turning operation of the steering handle to turn the aircraft at the minimum turning radius, the high / low speed switching device is provided. Is automatically switched to the high speed side, and the brake device for braking the rear wheels on the inside of the turn is actuated, so that turning with a small turning radius is achieved.

In particular, according to the present invention, since it is not necessary to depress the brake pedal, which is a heavy labor when a sharp turn is made on the ridge, the turn can be performed easily.

[Brief description of drawings]

FIG. 1 is a side view of a tractor.

FIG. 2 is an explanatory diagram of a main part.

FIG. 3 is a block diagram of a steering control device.

FIG. 4 is an explanatory diagram of steering control.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 tractor 2 engine 3 transmission case 10 front wheel clutch 37 brake device 44 steering control device 50 control means (controller)

Claims (1)

[Claims] 1. A high / low speed switching device for switching a driving state of front wheels to high / low speed, a pair of left and right brake devices for independently braking left and right rear wheels, and a steering angle for detecting a steering angle of front wheels. In the tractor having a detection device, when the steering angle detection device detects that the steering angle of the front wheels has been operated at a predetermined angle or more, the high / low speed switching device is switched to the high speed side, and A turning control device for a tractor, characterized in that a control means for braking the braking device is provided.