JPH058741A - Electric power steering structure for tractor - Google Patents

Abstract

PURPOSE:To decrease motive power loss, a housing space and a production cost respectively, by driving an electric actuator based on the torque difference of a steering wheel support shaft and a steering shaft, and by adding auxiliary power to a front wheel steering mechanism so as to make the torque difference zero. CONSTITUTION:Steering for right and left front wheels are operated by a steering wheel 6, interlocking and connecting a reduction gear 10 to the steering wheel 6 through a steering shaft 11, interlocking and connecting a steering gear box 12 to the reduction gear 10 through a drive shaft 13, and interlocking and connecting the right and left front wheels to the steering gear box 12 through a front wheel steering mechanism 14. An electric actuator 15 is linkage- connected to the reduction gear 10. A torque sensor 17 to detect each torque difference between them is interposed between a support shaft 16 of the steering wheel 6 and the steering shaft 11. The electric actuator 15 is driven by a control unit 18 based on the detecting signal from the torque 17, and it is controlled so as to make the torque difference zero.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electric power steering structure for a tractor.

[0002]

2. Description of the Related Art Conventionally, as one embodiment of a hydraulic power steering structure for a tractor, a reduction gear is linked to a steering wheel via a steering shaft, and a steering gear box is linked to the reduction gear via a drive shaft. , The left and right front wheels are interlockingly connected to the steering gear box through the front wheel steering mechanism, and the steering operation of the left and right front wheels can be performed by the handle, and the front wheel steering mechanism is provided with a hydraulic cylinder. Oil in the hydraulic tank is supplied to the hydraulic cylinder from the hydraulic pump provided in the prime mover in conjunction with the operation of the steering wheel, and the hydraulic cylinder is expanded / contracted to add a supplementary force to the front wheel steering mechanism. There are things that can be done.

[0003]

However, in the above hydraulic power steering structure, when the steering wheel is operated,
Since the hydraulic pump of the prime mover is always operated, the power supply force (for example, tilling horsepower) is supplied to the cultivator, which is the original purpose of the prime mover of the tractor.
There was a problem of causing a loss in.

Also, many hydraulic pipes and hydraulic devices are required, and it is difficult to store them in a limited space of a tractor, especially a small tractor.

[0005]

Therefore, in the present invention, a reduction gear is linked to a steering wheel via a steering shaft, a steering gear box is linked to the reduction gear via a drive shaft, and a steering gear box is connected to the steering gear box. The front left and right wheels are interlockingly connected via the front wheel steering mechanism to enable steering operation of the front left and right wheels by the handle, the speed reducer is interlockingly connected to the electric actuator, and it is connected to the handle shaft. A torque sensor that detects the difference between the torque of the support shaft and the torque of the steering shaft is provided between the steering shaft and the steering shaft, and the detection output from the torque sensor is input to the control unit. It is possible to add an assisting action to the front wheel steering mechanism so that the output value detected by the torque sensor becomes zero by operating the electric actuator. There is provided St. an electric power steering structure of the tractor to be.

[0006]

[Operation] When changing the traveling direction of the tractor to the left side or the right side, by rotating the handle, power is transmitted to the steering shaft → reduction gear → drive shaft → steering gear box → front wheel operation mechanism, The left-right front wheel can be turned to a required angle to change the running.

At this time, when the torque sensor interposed between the support shaft of the steering wheel and the steering shaft detects a difference between the torque of the support shaft and the torque of the steering shaft,
The detection output is input to the control unit, the electric actuator is operated via the control unit, and a force assisting action is added to the front wheel steering mechanism so that the detection output value of the torque sensor becomes zero. The operation of the handle can be lightened.

Moreover, since the electric actuator is used as the driving means for adding the assisting action to the front wheel steering mechanism, the horsepower of the motive power of the tractor is not reduced, and the power is not applied to the tiller. Power can be reliably supplied.

[0009]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1A shows a tractor equipped with an electric power steering structure according to the present invention, in which 1 is a vehicle frame, 2 is a motor part, 3 is a driving part, 4 is a front wheel,
5 is a rear wheel.

The driver 3 has a handle 6 at the front, a seat 7 at the rear of the handle 6, and various operation levers 8 at the left and right sides of the seat 7.

According to the present invention having the above-mentioned structure, the electric power steering mechanism P is provided between the steering wheel 6 and the left and right front wheels 4 and 4, and the mechanism P will be described below with reference to FIGS. Will be described with reference to.

That is, in the electric power steering mechanism P, as shown in FIGS. 2 and 3, the reduction gear is attached to the steering wheel 6.
The steering gear box 12 is connected to the speed reducer 10 via the drive shaft 13.
The left and right front wheels 4, 4 are interlocked with each other via the front wheel steering mechanism 14 to enable the steering operation of the left and right front wheels 4, 4 by the handle 6, and the speed reducer 10 is provided with an electric actuator. A torque sensor 17 is connected between the support shaft 16 of the steering wheel 6 and the steering shaft 11 for detecting the difference between the torque of the support shaft 16 and the torque of the steering shaft 11, and the same torque is provided. The detection output from the sensor 17 is input to the control unit 18, the electric actuator 15 is operated via the control unit 18, and the front wheel steering mechanism 14 is set so that the detection output value of the torque sensor 17 becomes zero. Auxiliary action can be added.

In FIG. 2, 11a, 11b, 13a and 13b are universal joints, and 19 is a joint. In FIG. 3, 14a is a pitman arm, 14b is a tie rod, 20 is a front axle case, and 21 is a transmission case.

The embodiment of the present invention is configured as described above, and according to this embodiment, the following operational effects are produced.

When the traveling of the tractor A is changed to the left side or the right side, by rotating the handle 6,
Steering shaft 11 → Reducer 10 → Drive shaft
13 → Steering gear box 12 → Power is transmitted to the front wheel steering mechanism 14 so that the left and right front wheels 4, 4 can be turned at a desired angle to change the traveling.

At this time, the torque sensor 17 interposed between the support shaft 16 of the steering wheel 6 and the steering shaft 11 is
When the difference between the torque of 16 and the torque of the steering shaft 11 is detected, the same detection output is input to the control unit 18, and the control unit
The electric actuator 15 is operated via 18 to lighten the operation of the handle 6 in order to add a supplementary force to the front wheel steering mechanism 14 so that the detection output value of the torque sensor 17 becomes zero. You can Moreover, since the electric actuator 15 is used as a drive means for adding an auxiliary action to the front wheel steering mechanism 14, the horsepower of the motive power of the tractor A is not reduced, and power is supplied to the tiller or the like. Can be reliably performed.

Further, as shown in FIG. 4, the expansion / contraction sliding portions 11c, 11d are provided on the upper and lower portions of the steering shaft 11, respectively, so that the torque sensor 17 can be slid in the axial direction. It can be absorbed by 11d, and the sensing accuracy of the torque sensor can be kept good.

5 and 6 show an electric actuator 15
The mounting structure is shown in Fig. 1. Mounting plate 22 is mounted on vehicle body frame 1, speed reducer 10 is mounted on the front part of the mounting plate 22, and electric actuator 15 is mounted on the rear part. Input shaft of machine 10
10a and 10a are interlockingly connected via a joint 19. 10b and 11e are bevel gears.

As described above, since the reduction gear 10 and the electric actuator 15 are attached to the attachment plate 22 and they are integrally attached to the vehicle body frame 1, the cores of the output shaft 15a and the input shaft 10a are arranged. The output can be performed accurately, the transmission efficiency from the electric actuator 15 to the speed reducer 10 can be increased, and labor saving (miniaturization) can be achieved.

As the joint 19, an inexpensive and compact one such as an involute joint can be used.

[0022]

According to the invention, the following effects can be obtained.

That is, since it is possible to add a supplementary force to the front wheel steering mechanism by the electric actuator, the driving force from the prime mover part to the cultivating part of this machine such as a hydraulic power steering structure is increased. There is no loss in power supply, and power can be reliably supplied to the cultivating part and the like, and the functions of the cultivating part and the like can be fully exerted.

The electric actuator has a simple structure and can be retrofitted. Moreover, unlike the hydraulic power steering structure, many hydraulic pipes and hydraulic equipment are not required, so a space for accommodating them is required. It is not necessary to provide a tractor, which is particularly effective for small tractors.

When the electric actuator is provided, the manufacturing cost can be reduced as compared with the hydraulic power steering structure.

[Brief description of drawings]

FIG. 1 is a side view of a tractor including an electric power steering structure according to the present invention.

FIG. 2 is a side view of an electric power steering mechanism.

FIG. 3 is an explanatory plan view of the mechanism.

FIG. 4 is a side view of a steering shaft as another embodiment.

FIG. 5 is a side view illustrating a mounting structure of an electric actuator.

FIG. 6 is an explanatory view of the same plane.

[Explanation of symbols]

 A tractor P Electric power steering mechanism 1 Body frame 2 Motor part 3 Driving part 4 Front wheel 5 Rear wheel 6 Handle 7 Seat 8 Various levers 10 Speed reducer 11 Steering shaft 12 Steering box 13 Drive shaft 14 Front wheel steering mechanism 15 Electric Actuator 16 Spindle 17 Torque sensor 18 Controller 19 Joint 20 Front axle case 21 Transmission case 22 Mounting plate

Claims (1)

Claims: 1. A steering gear is connected with a reduction gear 10 to a handle 6 via a steering shaft 11, and a steering gear box 12 is linked to the reduction gear 10 via a drive shaft 13. Left and right front wheels 4, 4 in box 12
Are interlockingly connected via the front wheel steering mechanism 14, and the handle 6
This enables steering operation of the left and right front wheels 4 and 4, and also connects the electric actuator 15 to the speed reducer 10 in an interlocking manner.
A torque sensor 17 for detecting the difference between the torque of the support shaft 16 and the torque of the steering shaft 11 is provided between the support shaft 16 of the steering wheel 6 and the steering shaft 11, and the detection output from the torque sensor 17 is provided. Can be input to the control unit 18 and the electric actuator 15 can be operated via the control unit 18 to add an assisting action to the front wheel steering mechanism 14 so that the detection output value of the torque sensor 17 becomes zero. The electric power steering structure of the tractor is characterized by