JPH09188270A - Steering device for working vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To stably and excellently carry out steering by varying an assist quantity of an electric power steering device assisting a steering wheel according to a traveling condition of a traveling device provided in a traveling vehicle body. SOLUTION: A detection signal from a torque sensor 12 is inputted into a controller 16 serving as an assist quantity change controlling means mounted on a traveling machine body. In the controller 16, on the basis of the detection result of the torque sensor 12, control signals S1-S5 for driving an electric motor 13 or an electromagnetic clutch 17 are outputted by means of a computing means 16A consisting of a microcomputer. On the basis of these control signals S1-S5, a driving signal driving the electric motor 13 and the like is outputted by means of a driving means 16B. In this way, steering can be excellently carried out stably.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a steering device for a work vehicle equipped with an electric power steering device that assists a steering wheel.

[0002]

2. Description of the Related Art Conventionally, as a steering apparatus for a work vehicle of this type, a steering wheel is simply assisted by a constant torque.

[0003]

However, in the above-mentioned conventional structure, for example, in a paddy field working vehicle such as a passenger type rice transplanter, when the vehicle is in a traveling state in which the direction is largely changed in a headland, There are times when the vehicle is in a traveling state where it keeps traveling almost straight, such as when traveling, and when making a large turn, the amount of assist is increased to perform light steering,
On the other hand, in the case of working traveling in a state where it is almost straight, the steering amount is set to be relatively heavy so that the steering amount will not be too light and will not cause unnecessary meandering. It has been desirable to be able to change and adjust the assist amount of the steering wheel according to the above.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a steering apparatus for a work vehicle that can be adjusted so that an appropriate assist amount can be obtained according to a running state.

[0005]

[Means for Solving the Problems]

(Structure) A steering apparatus for a work vehicle according to claim 1 of the present invention includes an electric power steering apparatus for assisting a steering wheel, and the electric power steering apparatus according to a traveling state of the traveling apparatus provided on a traveling vehicle body. A characteristic configuration is that an assist amount change control means for changing the assist amount is provided.

(Operation) According to the configuration of claim 1 of the present invention, the assist amount of the electric power steering device is changed according to the traveling state of the traveling device. In the case of a driving state in which the direction is greatly changed, the assist amount is set to a large amount to lighten the steering, and in the case of a driving state in which the vehicle travels in a straight line, the steering is not unnecessary. Thus, proper steering can be performed by setting a small assist amount and changing to a relatively heavy steering state.

(Effect) Therefore, according to the structure of claim 1 of the present invention, since the steering is appropriately performed according to the traveling state, the steering becomes unduly light or vice versa. Since it does not, stable steering can be performed well.

(Structure) The steering apparatus for a work vehicle according to claim 2 of the present invention is the steering apparatus according to claim 1, wherein the assist amount change control means is a speed that imparts a driving speed difference to the left and right wheels of the traveling device. The assisting amount of the electric power steering device is changed according to the operating state of the restricting means.

(Operation) According to the configuration of claim 2 of the present invention, the case where the vehicle body is turned by operating the speed regulating means for providing the driving speed difference to the left and right wheels in the traveling device, and such a case The assist amount of the electric power steering device is changed depending on whether the traveling device is normally operated without speed regulation. Then, as in the former case, when the speed regulating means that gives the driving speed difference to the left and right wheels of the traveling device is actuated, specifically, the side clutch that turns on and off the power transmission to each of the left and right wheels of the traveling device. When the side brakes that individually brake the left and right wheels are activated, it is determined that the vehicle is in a direction-changing state, the assist amount is increased, and steering is made lighter.
As in the latter case, when the speed control means is not operating, it is determined that the vehicle is in a normal traveling state, and the assist amount is set to a relatively small state so that steering is not unduly lightened. Become.

(Effect) Therefore, according to the configuration of claim 2 of the present invention, the side clutch or the side clutch that is in a normal traveling state or that largely changes the direction of the machine body based on the operation of the speed regulating means. It is controlled so that steering can be performed with an assist amount most suitable for the traveling state by determining whether or not the vehicle is in a traveling state in which a speed regulating means such as a side brake is operated, so that the steering can be stably and favorably performed.

(Structure) According to a third aspect of the present invention, in the steering apparatus for a working vehicle according to the first aspect, the assist amount change control means shifts the power transmitted from the engine to the traveling device. The assist amount of the electric power steering device is changed according to vehicle speed information obtained based on the shift operation amount of the hydrostatic continuously variable transmission and the accelerator operation amount of the engine. The configuration.

According to the third aspect of the present invention, the actual vehicle speed is indirectly determined by calculating the product of the shift operation amount of the hydrostatic continuously variable transmission and the accelerator operation amount of the engine. Based on this calculation result, for example, when the vehicle speed is high, the assist amount is reduced to make the steering heavy, and when the vehicle speed is low, the assist amount is increased to make the steering lighter. As a result, appropriate steering can be performed according to the vehicle speed.

(Effect) Therefore, according to the configuration according to claim 3 of the present invention, is it a high-speed running state in which excessively large steering is not performed based on the operating states of the hydrostatic continuously variable transmission and the engine? Or, it is judged whether or not the vehicle is in a low-speed traveling state that causes the aircraft to make a large turn, and the result of that determination is that the steering amount is controlled so that the steering assist can be performed with the most suitable amount of assistance. In addition to being excellent, the sensor for exclusive use for detecting the vehicle speed is not required, so that it can be constructed at low cost.

[0014]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a riding type rice transplanter as an example of a work vehicle. In this riding type rice transplanter, an engine 4, a mission case 5, a boarding control unit 6 and the like are mounted on a traveling machine body 3 supported by a pair of left and right front wheels 1, 1 and rear wheels 2, 2 so as to travel. , The seedling planting device 8 at the rear end of the traveling machine body 3 via the four-link mechanism 7.
Is configured so that it can be moved up and down.

As shown in FIGS. 1 and 2, a steering handle 9 is installed in the boarding control section 6, and the steering handle 9 and the front wheels 1 and 1 are electrically powered. It is interlockingly connected through 10. More specifically, the handle shaft 1 of the steering handle 9
1 is provided with a torque sensor 12 for detecting a turning torque of the steering wheel 9, and an electric motor 13 for applying an assisting force for turning the handle shaft 11 based on a detection result of the torque sensor 12 is electromagnetically driven. Clutch 1
7 and the gear interlocking mechanism 14 through the handle shaft 11
It is linked and linked. The handle shaft 11 and the front wheels 1 and 1 are interlocked with each other via a linkage mechanism such as a pitman arm, a knuckle arm, and a tie rod. The detection signal of the torque sensor 12 is input to the control device 16 mounted on the traveling machine body 3 as the assist amount change control means. Then, the control device 16 has a drive signal for driving and controlling the electric motor 13 based on the detection result of the torque sensor 12 and a drive signal for driving and controlling the electromagnetic clutch 17 for turning on and off the transmission of the output of the electric motor 13. Is output. That is, as shown in FIG. 2, the control device 16 inputs the detection signal of the torque sensor 12 and controls the control signal S for driving the electric motor 13 or the electromagnetic clutch 17.
Operation means 16A including a microcomputer for outputting 1, S2, S3, S4, S5 and control signals S1, S2, S for these
The drive means 16B for outputting a drive signal for actually driving the electric motor 13 and the like based on S3, S4 and S5.

Further, as shown in FIG. 1 and FIG. 2, a pair of left and right side brake operating pedals on the step portion 18 of the boarding operation portion 6 of the traveling machine body 3 are operable by a driver seated on a seat 19 to operate the pedals. 20L and 20R are arranged. This side brake operating pedal 20L, 20R
And the side brakes 21L and 21R as the traveling device operation restricting means provided on the respective axles of the rear wheels 2 and 2 as the traveling device, are linked through a mechanical linkage mechanism such as a rod or a link (not shown). ing. Then, limit switches 22L and 22R for detecting whether or not each of the side brake operating pedals 20L and 20R are depressed are provided, and the detection signals of these limit switches 22L and 22R are the control device. It is input to 16 arithmetic means 16A. Further, the control panel 23 of the boarding control unit 6 is provided with an adjusting potentiometer 24 for artificially appropriately setting the standard value of the assist amount of the electric power steering device 10, and the adjusting potentiometer 24 is also provided.
Is output to the arithmetic means 16A of the control device 16. Then, the calculating means 16A is configured to operate the limit switch 2
Based on the presence or absence of the detection signal input from 2L and 22R,
When the detection signals from both limit switches 22L and 22R are not input, that is, when neither of the side brake operating pedals 20L and 20R is depressed, the standard assist preset by the adjusting potentiometer 24 is set in advance. Control signals S1, S2 for driving the electric motor 13 so as to assist the steering wheel 9 by the amount.
S3 and S4 and a control signal S5 for switching the electromagnetic clutch 17 from the disengaged state to the engaged state are output. When the detection signal is input only from one of the limit switches 22L and 22R, the electric motor 13 is driven so as to assist the steering wheel 9 with a larger assist amount at a predetermined rate than the standard assist amount. Control signals S1, S
2, S3, S4 and a control signal S5 for switching the electromagnetic clutch 17 from the disengaged state to the engaged state are output.

With the above structure, the side brake 21L,
In a normal traveling state in which steering is performed only by the steering wheel 9 without using 21R, steering is performed with a standard assist amount, and steering is performed such that the side brakes 21L and 21R are also used to make a sharp turn. In this case, steering is performed with an assist amount that is larger than the standard assist amount by a predetermined ratio. Therefore, in the normal traveling state, appropriate assist is provided to the extent that the steering is not unduly lightened, and in the traveling state in which the vehicle body makes a sharp turn, such as in a headland, the side brake 21L , 21R, the assist is performed with an assist amount that is greater than the standard assist amount by a predetermined ratio based on the detection result that only one of them is being used. Further, since the assist amount is automatically changed according to the traveling state, it does not take time to artificially switch.

[Another Embodiment] Another embodiment (corresponding to claim 3) will be described below with reference to the drawings. The riding type rice transplanter will be described, and the same structures as those in the above-described embodiment will not be described and will be denoted by the same reference numerals. As shown in FIGS. 1 and 3, the transmission case 5 to which the power from the engine 4 is transmitted has a hydrostatic continuously variable transmission 25.
HST for detecting the amount of rotation of the shift operation shaft of the hydrostatic stepless transmission 25 in order to detect the amount of shift operation of the hydrostatic stepless transmission 25.
(Abbreviated name of hydrostatic continuously variable transmission) A potentiometer 27 is provided as an operation position sensor. The detection signal of the potentiometer 27 is input to the arithmetic means 16A of the control device 16 as the assist amount change control means. or,
A second potentiometer 28 is provided as a sensor for detecting an accelerator amount that detects an operation angle of an accelerator operating lever for detecting an accelerator operation amount of an engine 4 mounted on the traveling machine body 3, and the second potentiometer 28 detects the second potentiometer 28. The signal is also input to the calculating means 16A of the control device 16. The calculation means 16A is configured so that the accelerator operation amount detected by the second potentiometer 28, that is, the engine speed that is indirectly detected, and the shift state of the hydrostatic continuously variable transmission 25, that is, the hydrostatic continuously variable transmission. The hydrostatic stepless transmission 2 according to the detection result detected by the potentiometer 27 that detects the operation position of the shift operation shaft (not shown) for adjusting the swash plate angle of 25 as the rotation angle of the shaft.
The vehicle speed information V is calculated on the basis of the product of the input rotational speed with respect to 5 and the degree of gear shift, and the electric power steering is in accordance with the calculated vehicle speed information V, for example, in a relationship almost inversely proportional to the vehicle speed information V. It is configured to set the assist amount of the device 10. And this calculating means 1
The PWM signals S1 and S2 for driving the electric motor 13 for assisting the steering wheel 9 from 6A, the steering direction setting control signals S3 and S4, and the electromagnetic clutch 17 driving control signal S5 are output to the driving means 16B. To do. The drive means 16B outputs a signal for driving the electric motor 13 and for engaging and disengaging the electromagnetic clutch 17.

Although the side brake is exemplified as the speed regulating means in the above-mentioned another embodiment, a side clutch for turning on / off the transmission to the right and left wheels may be used.

In the claims, reference numerals are provided for convenience of comparison with the drawings, but the present invention is not limited to the configuration shown in the attached drawings.

[Brief description of the drawings]

FIG. 1 is an overall side view showing a riding type rice transplanter.

FIG. 2 is a schematic explanatory view showing an electric power steering device and the like.

FIG. 3 is a schematic explanatory view showing an electric power steering device and the like of another embodiment.

[Explanation of symbols]

 1, 2 traveling device 3 traveling vehicle body 4 engine 9 steering wheel 10 electric power steering device 16 assist amount control means 21L, 21R speed regulation means

Claims (3)

[Claims] 1. An electric power steering device (10) for assisting a steering wheel (9), and the electric power according to a traveling state of traveling devices (1), (2) provided on a traveling vehicle body (3). Assist amount change control means (16) for changing the assist amount of the steering device (10)
A steering device for a work vehicle equipped with. 2. The assist amount change control means (16)
Is configured to change the assist amount of the electric power steering device (10) in accordance with the operating states of speed regulating means (21L) and (21R) that give a difference in driving speed to the left and right wheels of the traveling device (2). The steering apparatus for the work vehicle according to claim 1. 3. The assist amount change control means (16)
Is based on a shift operation amount of a hydrostatic continuously variable transmission (25) that shifts the power transmitted from the engine (4) to the traveling device (2) and an accelerator operation amount of the engine (4). The work vehicle steering system according to claim 1, wherein the assist amount of the electric power steering system (10) is changed according to the obtained vehicle speed information.