JPH0880757A - Front wheel accelerating device for tractor - Google Patents

Abstract

PURPOSE: To prevent a detection section from being affected by the external environment by arranging an acceleration steering angle detecting sensor at the center section of a front axle case, and storing the detection section in the front axle case. CONSTITUTION: A power steering device rotates front wheels via both rod type steering cylinders 3. A front wheel accelerating device detects the steering angle of a tractor and accelerates the front wheels when the steering angle becomes the prescribed angle or above. A shaft 4 constituting a steering angle detecting sensor is arranged nearly parallel with each steering cylinders 3 and slidably supported in a front axle case 1, and the center section of the steering cylinder 3 and the detection section 10 of the steering angle detecting sensor are stored in the front axle case 1. The detection section 10 is prevented from being affected by the external environment such as mud, soil, and dust.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mounting structure for a speed-increasing steering angle detection sensor of a front-wheel speed-increasing mechanism, which enables a smooth turning of a tractor at the end of a field without ruining the field.

[0002]

2. Description of the Related Art Conventionally, a front wheel speed increasing mechanism and a double rod type steering cylinder type power steering device are provided.
The technique of attaching the front wheel steering angle sensor to the front wheel final case is known from Japanese Utility Model Publication Nos. 6-264 and 6-27459, and the front wheel steering angle sensor is mounted on the outside of the front axle case. The technique is known from Japanese Utility Model Publication No. 6-22599.

[0003]

However, in the case of the former technique, since the sensor is attached to the front final case, the wiring of the sensor must be wired from the central part of the case to the case, and the soil, There was a risk of breaking the wire when hit by stones or grass. Further, in the latter technique, since the sensor is installed outside the front axle case, adhesion of soil or the like to the sensor may cause a failure.

[0004]

In order to solve such problems, the present invention provides a power steering device for rotating front wheels by a double rod type steering cylinder,
In a configuration equipped with a front wheel speed increasing device that detects the steering angle of the tractor and accelerates the front wheels when it rotates more than a set angle, the shaft that constitutes the steering angle detection sensor is arranged substantially parallel to the steering cylinder. Then, the front axle case is slidably supported, and the central portion of the steering cylinder and the detection portion of the steering angle detection sensor are housed in the front axle case.

[0005]

[Operation] With the above configuration, the speed-increasing steering angle detection sensor is located in the center of the front axle case away from the final case near the front wheels, and the detection portion is housed in the front axle case. As a result, the detecting section is not affected by the external environment such as mud, dirt, dust and the like.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The problems to be solved by the present invention and the means for solving the problems are as described above. Next, the structure of the embodiments shown in the accompanying drawings will be described. 1 is an overall side view of the tractor, FIG. 2 is a front view showing a front wheel speed increasing steering angle sensor mechanism of the present invention, FIG. 3 is a sectional view showing the same front wheel speed increasing steering angle sensor mechanism, and FIG. It is a hydraulic circuit diagram of a speed mechanism.

In FIGS. 1 and 4, power is transmitted to a mission case M rearward of an engine arranged at the front of the tractor A, gears are changed in the transmission case M, and rear wheels 20 are passed through a rear wheel differential mechanism. Further, the front wheel transmission is housed in the power transmission path in the transmission case M, and the front wheel drive hydraulic clutch 24 and the front wheel speed increasing clutch 23 of the same speed as the rear wheels are arranged. From the front wheel drive output shaft projecting from the front shaft, the power is transmitted to the input shaft 19 of the front axle case 1 via the transmission shaft 16, and the power is transmitted from the input shaft 19 to the front differential mechanism via the pinion 17.
The front wheels 21 are driven.

The front wheel speed increasing hydraulic clutch 23 and the front wheel driving hydraulic clutch 24 can be operated by selectively sending pressure oil by switching the electromagnetic valve 25.
Can be switched by energizing and operating the solenoid 25a. The solenoid 25a is connected to the switch 12 via the controller 26. As described later, the front wheels are rotated by a set angle or more, and the switch 12 is turned on. , The front wheels are accelerated during work. This work can be detected by providing a switch on the work clutch lever or the like and connecting it to the controller.

Further, as shown in FIG. 2, a double rod type steering cylinder 3 is laterally installed laterally in the front portion of the front axle case 1 in which the front differential mechanism is housed, and the central portion thereof is attached to the front axle case 1. When the steering wheel 18 housed and placed in the driver's seat is rotated, the switching valve provided at the lower portion of the steering wheel 18 is switched to send pressure oil to the steering cylinder 3 and the steering wheel 18 is operated.
The piston rod 3a on the side where is rotated is extended. The tip of the piston rod 3a is connected to a tie rod 8 via a joint 9, and a knuckle arm 14 is connected to the tip of the tie rod 8.
Is fixed to the final case 27 and steering 1
The front wheel 21 is configured to be steerably rotated about the kingpin by the rotation of 8.

When the steering angle of the front wheels 21 reaches or exceeds the set angle, the front wheel speed increasing device is operated, and in order to detect the turning angle of the front wheels 21, the steering cylinder 3 and A shaft type steering angle sensor unit B is arranged in parallel. As shown in FIGS. 2 and 3, the steering angle sensor unit B is disposed in front of the double rod type steering cylinder 3 and The angle sensor unit B is symmetrically arranged with respect to the center line of the tractor A in the left-right direction, and the center portion of the shaft 4 is inserted into the front axle case 1 via the cylinders 6 and 6 so as to be slidable left and right. Inside the front axle case 1, the lubricating oil filled therein is applied.

The central portion of the shaft 4 is formed with a groove portion 4a having a reduced diameter and is centered in a straight traveling state. The detection portion 10 is provided in the front axle case 1 above the groove portion 4a.
Is formed with a fitting hole 1a, and the balls 11 and 11 are slidably inserted in the fitting hole 1a up and down, the lower end of the ball 11 is fitted into the groove portion 4a, and the ball 11 is provided above the ball 11 with a switch. 12 is screwed, and an abutting portion 12a at the lower end thereof is disposed so as to abut the ball 11. Plates 7 and 7 are vertically (forward and backward) fixed to both ends of the shaft 4, and the plates 7 and 7 are extended rearward to open insertion holes 7a and 7a, respectively. 7
a is the piston rod 3 of the steering cylinder 3
a is loosely fitted.

Further, springs 5 and 5 are fitted onto the shaft 4 on the axial center side of the cylinders 6 and 6 slidably supporting the shaft 4 and inside the shaft 4 support portion of the front axle case 1. It is internally installed, and the springs 5 and 5 are stopped by retaining rings 15 and 15 which are fitted onto the shaft 4,
The shaft 4 is biased so that the shaft 4 is located at a symmetrical position, that is, the groove 4a is located at the center.

With such a structure, when the steering wheel 18 is rotated, the steering cylinder 3 is also driven and the front wheels 21 are also rotated, so that the steering wheel 3 can be turned. And
When the angle becomes equal to or larger than the set angle, the joint 9 contacts and pushes the plate 7, and the shaft 4 connected to the plate 7 also slides. When the shaft 4 slides, the groove 4a
Also, the ball 11 fitted in the groove 4a is pushed upward and slides, the contact portion 12a is pushed, and the switch 12 is turned on. At this time, since the vehicle is traveling on the road or the like when not in operation, the controller 26 does not operate the solenoid 25a to prevent a sudden turn to avoid danger, and when in operation, the solenoid 25a is operated to operate the electromagnetic valve 25. Is switched to stop the pressure oil from being fed to the front wheel drive hydraulic clutch 24, feed the pressure oil to the front wheel speed increasing clutch 23, and operate the clutch to put the front wheel 21 into the speed increasing state. Further, when the steering wheel 18 is returned to the straight traveling state, the joint 9 is separated from the plate 7 and is not pushed, the shaft 4 is centered by the restoring force of the spring 5, and the ball 11 is fitted into the groove portion 4a. When the switch 12 is lowered, the switch 12 is turned off, the solenoid 25a is also turned off, and the front and rear wheels travel at a constant speed.

[0014]

As constructed above, the present invention has the following effects. In other words, since the steering cylinder and the mechanical part of the steering angle detector are housed in the front axle case, the steering cylinder and the shaft and ball detectors are protected by the front axle case. The lubricating oil filled in the case did not corrode, and it was able to slide smoothly without being affected by dirt, mud, dust, etc., and reliability and accuracy could be improved.

[Brief description of drawings]

FIG. 1 is an overall side view of a tractor.

FIG. 2 is a front view showing a front wheel speed-increasing steering angle sensor mechanism of the present invention.

FIG. 3 is a sectional view showing a front wheel speed-increasing steering angle sensor mechanism.

FIG. 4 is a hydraulic circuit diagram of a front wheel speed increasing mechanism.

[Explanation of symbols]

 A tractor B sensor unit 1 front axle case 4 shaft 10 detector 11 ball 12 switch

Claims (1)

[Claims] 1. A structure comprising a power steering device for rotating front wheels by means of a dual rod type steering cylinder, and a front wheel speed increasing device for detecting a steering angle of a tractor and increasing the speed of the front wheels when the steering angle exceeds a set angle. In, a shaft that constitutes a steering angle detection sensor is arranged substantially parallel to the steering cylinder, slidably supported on a front axle case, and a central portion of the steering cylinder and a detection portion of the steering angle detection sensor. The front wheel speed-increasing device for the tractor, which is characterized by housing the front axle case.