JPH0880756A - Four-wheel drive work vehicle - Google Patents

Abstract

PURPOSE: To provide a four-wheel drive work vehicle capable of simplifying the action of an operator at a butt where the direction of a vehicle body is largely changed. CONSTITUTION: This four-wheel drive work vehicle is provided with a front wheel transmission mechanism 16 capable of being switched to the acceleration state setting the revolving speed of front wheels 1 higher than the revolving speed of rear wheels 2 or the constant speed state setting the revolving speeds of the front wheels 1 and rear wheels 2 nearly equal, a linking means B linking the front wheel transmission mechanism 16 and a steering device A to switch the front wheel transmission mechanism 16 to the acceleration state from the constant speed state when the right or left steering angle of the steering device A against the front wheels 1 becomes a prescribed angle or above, and a work device attitude control means 100 forcibly changing the attitude of a work device 6 mounted on a vehicle body from the work attitude to the nonwork attitude interlockingly when the right or left steering angle of the steering device A becomes the prescribed angle and the front wheel transmission mechanism 16 is switched from the constant speed state to the acceleration state.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a speed increasing state in which the rotational speed of front wheels is set higher than the rotational speed of rear wheels, and a constant speed in which the rotational speeds of the front and rear wheels are set to approximately the same speed. The front wheel speed change mechanism is provided so that the front wheel speed change mechanism can be switched between the constant speed state and the speed increase state when the left and right operation angle of the steering device with respect to the front wheel exceeds a set angle. The present invention relates to a four-wheel drive work vehicle provided with a linking means for linking the steering device with the steering device.

[0002]

2. Description of the Related Art Conventionally, in a four-wheel drive type work vehicle, such as an agricultural tractor, equipped with a working device such as a rotary tiller at the rear part of a traveling vehicle, the next work process is performed on a headland of a field. When the direction is changed to, the steering operation and the operation of raising the work device from the ground work posture to the non-work posture are performed.

[0003]

Therefore, in the four-wheel drive type work vehicle having the above-mentioned conventional structure, the steering operation and the non-working posture of the working device are changed at a portion such as a headland where the direction of the vehicle body is largely changed. The operator has to perform both the changing operation and the changing operation, which is troublesome. The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a four-wheel drive type work vehicle that can be easily operated by an operator at a location such as a headland that greatly changes the direction of the vehicle body.

[0004]

In order to achieve the above object, a four-wheel drive work vehicle according to the present invention has a speed increasing state in which the rotation speed of the front wheels is set higher than the rotation speed of the rear wheels. A front wheel transmission mechanism capable of switching the rotation speeds of the front wheels and the rear wheels to a constant speed state in which the rotation speeds of the front wheels and the rear wheels are set to substantially the same speed. In a four-wheel drive work vehicle provided with a linking means for linking the front wheel speed change mechanism and the steering device so that the mechanism is switched from a constant speed state to a speed increasing state, a left and right operating angle of the steering device is set. When the front wheel speed change mechanism is switched from the constant speed state to the speed increasing state when the angle is greater than or equal to the angle, the working device mounted on the vehicle body is
It is characterized in that it is provided with a work device posture control means for forcibly changing the posture from the working posture to the non-working posture.
Further, in order to achieve the above object, the four-wheel drive work vehicle according to the present invention has a speed-up state in which the rotation speed of the front wheels is set higher than the rotation speed of the rear wheels, and the front and rear wheels are A front wheel speed change mechanism that can switch the rotation speed to a constant speed state that is set to approximately the same speed is provided, and the front wheel speed change mechanism is increased from the constant speed state when the left-right operation angle of the steering device with respect to the front wheels becomes equal to or more than a set angle. A switching means is provided to link the front wheel speed change mechanism and the steering device so as to switch to the high speed state, and further, when the traveling speed change device is switched to the reverse drive,
In a four-wheel drive type work vehicle including a forcible lifting control means for forcibly lifting a working device mounted on a vehicle body, the front wheel speed change mechanism is fixed by setting the left and right operating angles of the steering device to a set angle or more. In conjunction with switching from the high speed state to the high speed state, the forcible raising control means and the front wheel transmission mechanism are linked so as to forcibly raise the working device from the working posture to the non-working posture. The operation and effect of the characteristic configuration which may be configured as follows are as follows.

[0005]

In other words, when the front wheels are steered by more than the set angle in a place where the direction of the vehicle body is greatly changed, such as in a headland of a farm field, the rotation speed of the front wheels is increased more than that of the rear wheels to roughen the ground by the wheels. While turning suddenly while suppressing the above, the working device is forced to change its posture to a non-working posture in conjunction with the sudden turning operation. If the posture change is applied to work in which the work device is forcibly lifted when the vehicle moves backward, if the front wheels are steered by more than the set angle, they will be linked to the sudden turning operation. As a result, the work device is forcibly operated so as to be in a non-working posture.

[0006]

As described above, the steering device is automatically switched to the non-working posture so as not to hinder the turning by simply performing the steering operation at a portion where the direction of the vehicle body is largely changed. It is no longer necessary to perform the operation for setting the work posture, and the operation of the operator only needs to be a steering operation, which is simple and improves workability.

[0007]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 2 shows an agricultural tractor as an example of a four-wheel drive work vehicle. This agricultural tractor supports a vehicle body 3 by a pair of left and right front wheels 1, 1 and a pair of left and right rear wheels 2, 2, and also has a drive section 4 and a control section 5 on the vehicle body 3.
And the like, and the rear end of the vehicle body 3 is equipped with a rotary tiller 6, which is an example of a working device, so as to be vertically movable.

As shown in FIG. 1, a drag link 8 linked to a steering handle 7 arranged on the control section 5.
Is linked to the knuckle arm 9 and the pitman arm 11 supported by the front axle case 10 and the left and right knuckle arms 9 and 9 are linked and linked by tie rods 12 and 12 to form a steering device A. On the other hand, a transmission shaft 15 for the front wheel 1 is provided in parallel with the output transmission shaft 14 for supplying power to the rear wheel differential mechanism 13 from the engine 4a as the prime mover 4 via the traveling transmission 4b, and the pair of hydraulic clutches C
A gear type front wheel speed change mechanism 16 is provided which can change the speed change state by C1 and C2. The front wheel transmission mechanism 16 has a speed increasing state in which the rotation speed of the front wheels 1 is set higher than that of the rear wheels 2 and a constant speed state in which the rotation speeds of the front wheels 1 and the rear wheels 2 are set to be substantially the same. The gear and the like are configured to be switchable to and. Then, as shown in FIG. 1, the disc-shaped cam 17 is fixed to the rotational axis position of the front wheel transmission case (not shown) that rotates integrally with the left knuckle arm 9, and
A limit switch 18 for detecting that the cam 17 rotates by a set angle or more is provided.
The detection result of 1 is input to the control device 19.
On the other hand, when an electromagnetic control valve 20 is provided in the pressure oil supply path to the hydraulic clutches C1 and C2, and the limit switch 18 detects the rotation of the cam 17 by a set angle or more, the speed increasing hydraulic clutch C1 is set. Electromagnetic control valve 20 to supply pressure oil
Is controlled by the control device 19. The electromagnetic control valve 20 is a three-position switching type, so that power transmission to the front wheels 1 is cut off at the neutral position N, pressure oil is supplied to the speed increasing hydraulic clutch C1 at the high speed position H, and At the constant speed position L, control is performed so that pressure oil is supplied to the constant speed hydraulic clutch C2. Here, the cam 17 and the limit switch 18
The control device 19 constitutes a linking means B.

As shown in FIGS. 1 and 2, the rotary tiller 6 is mounted on the rear end of the vehicle body 3 so as to be movable up and down via a link mechanism 22 which is operated to move up and down by a hydraulic cylinder 21. A potentiometer 23 for detecting a swing angle of the link mechanism 22 with respect to the vehicle body 3 is provided at a swing axis center of the link mechanism 22, and a detection signal of the potentiometer 23 is input to the control device 19. ing. And the steering wheel 7
A laterally swingable forward / backward movement switching lever 24 for performing forward / backward movement switching is provided on the lateral side of the limit switch, and a limit switch for detecting that the forward / backward movement switching lever 24 is operated in a reverse direction. 25, and this limit switch 2
The signal from 5 is input to the control device 19. The control device 19 electromagnetically controls the hydraulic cylinder 21 so as to forcibly switch the hydraulic cylinder 21 to the raised posture that is the non-working posture when the forward / reverse switching lever 24 is operated to move backward. An operation signal for operating the valve 26 is output, and so-called backup control is executed.

Further, the control device 19 operates the electromagnetic control valve 20 so as to supply the pressure oil to the speed increasing hydraulic clutch C1 when the limit switch 18 detects the rotation of the cam 17 over the set angle. However, at the same time, it is equipped with a working device posture control means 100 for manipulating the electromagnetic control valve 26 to forcibly switch the rotary tiller 6 to the raised posture that is the non-working posture. Constitutes a forcible ascent means for forcibly ascending. The control device 19 and the front wheel speed increasing mechanism 16 are linked via the hydraulic clutches C1 and C2. As a result, when the steering wheel 7 is steered largely to switch to the front wheel speed increasing state in order to change the direction of the vehicle body 3 in the headland of the field, the rotary tiller 6 is automatically forcibly raised to the non-working posture. Of. At the start of the work, when the operator operates the work device lowering operation switch of the control panel section in order to lower the rotor cultivator 6 in the raised posture to a predetermined ground work position, the control device 1
9 operates the electromagnetic control valve 26 based on the signal from the switch to automatically lower the rotary tiller 6 to a predetermined position detected by the potentiometer 23.

[Other Embodiments] The linking means for linking the steering mechanism and the front wheel speed change mechanism may be mechanically constructed. In this case, as shown in FIG. 3, the limit switch 18 for detecting the steering angle equal to or larger than the set angle is connected in parallel with the limit switch 25 for reverse drive detection in the backup control, so that the backup control is performed by detecting the steering angle equal to or larger than the set angle. Can be executed to function as in the above embodiment.
Further, by interposing the on / off switch 27 for backup control in the circuit of the limit switch 25, it becomes possible to cancel the backup control of the working device linked to the reverse shift and the sharp turn operation. As a four-wheel drive type work vehicle, it can be applied to agricultural work vehicles such as rice transplanters and other industrial four-wheel drive type work vehicles in addition to agricultural tractors. It can also be applied to things such as changing the posture.

It should be noted that although reference numerals are given in the claims for convenience of comparison with the drawings, the present invention is not limited to the configurations of the accompanying drawings by the entry.

[Brief description of drawings]

FIG. 1 is a schematic explanatory diagram showing an overall configuration.

FIG. 2 is an overall side view showing an agricultural tractor.

FIG. 3 is a configuration diagram of a main part of another embodiment.

[Explanation of symbols]

 1 Front Wheel 2 Rear Wheel 3 Vehicle Body 4b Travel Transmission 6 Working Device 16 Front Wheel Transmission Mechanism 19 Forced Raising Control Means 100 Working Device Posture Control Means A Steering Device B Coordination Means

Claims (2)

[Claims] 1. A speed increasing state in which the rotational speed of the front wheel (1) is set higher than the rotational speed of the rear wheel (2) and the rotational speed of the front wheel (1) and the rear wheel (2) are substantially the same. A front wheel speed change mechanism (16) capable of switching to a constant speed set to a speed is provided, and when the left and right operation angle of the steering device (A) with respect to the front wheel (1) becomes a set angle or more, the front wheel speed change mechanism (16). ) From the constant speed state to the speed increasing state,
A four-wheel drive work vehicle provided with a linking means (B) for linking the front wheel speed change mechanism (16) and the steering device (A), wherein a left-right operation angle of the steering device (A) is set. When the front wheel speed change mechanism (16) is switched from the constant speed state to the speed increasing state when the angle is equal to or greater than the angle, the working device (6) mounted on the vehicle body (3) is moved from the working position to the non-working position. A four-wheel drive work vehicle including a work device posture control means (100) for forcibly changing the posture. 2. A speed increasing state in which the rotation speed of the front wheel (1) is set higher than that of the rear wheel (2) and the rotation speed of the front wheel (1) and the rear wheel (2) are substantially the same. A front wheel speed change mechanism (16) capable of switching to a constant speed set to a speed is provided, and when the left and right operation angle of the steering device (A) with respect to the front wheel (1) becomes a set angle or more, the front wheel speed change mechanism (16). ) From the constant speed state to the speed increasing state,
A linking means (B) for linking the front wheel speed change mechanism (16) and the steering device (A) is provided, and when the traveling speed changer (4b) is switched to the reverse drive, the vehicle body (3) is equipped. A four-wheel drive type work vehicle including a forced raising control means (19) for forcibly raising the working device (6), wherein the left-right operation angle of the steering device (A) is a set angle or more. In conjunction with switching the front wheel speed change mechanism (16) from the constant speed state to the speed increasing state, the compulsory lifting operation of the working device (6) from the working posture to the non-working posture is performed. A four-wheel drive type working vehicle in which the ascending control means (19) and the front wheel transmission mechanism (16) are linked.