JPH08119129A - Power steering structure for work vehicle - Google Patents

Abstract

PURPOSE: To increase a steering angle for front wheels, regarding a power steering structure for the front wheels of a work vehicle. CONSTITUTION: A pitman arm 7 and the actuator section 8 of a power steering device for driving the pitman arm 7 are vertically laid on a body frame 1 forward of a front wheel axle 6a, so as to be positioned within the transverse breadth of right and left frame sections 1, and capable of free oscillation right and left with the arm 7 kept as a front support point (a). The pitman arm 7 and a front wheel knuckle arm are jointed to each other via tie rods 12 and 12. In addition, the actuator section 8 of the device is laid, so as to be positioned within the vertical breadth of the frame 1, and the pitman arm 7 is positioned below the lower end of the frame 1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power steering structure for front wheels of a work vehicle such as a tractor and a riding lawn mower.

[0002]

2. Description of the Related Art Conventionally, in order to drive the front wheels of a tractor through a power steering device, Japanese Patent Application Laid-Open No. 56-95712.
As disclosed in Japanese Patent Laid-Open Publication No. 2005-163, it is adapted to be driven via a linkage type separate type power steering device in which a pitman arm and a knuckle arm for front wheels are connected by a power cylinder.

[0003]

Since the power cylinder for connecting the pitman arm and the knuckle arm is arranged on the lateral side of the airframe, when the steering handle is largely cut, the front wheel hits the piston rod of the power cylinder. Therefore, there is an inconvenience that the cutting angle of the front wheels cannot be increased so much.

An object of the present invention is to increase the turning angle of the front wheels and to arrange the power steering device compactly so as to avoid contact with other objects.

[0005]

A first characteristic structure of the present invention is to provide a power for driving a pitman arm and a pitman arm in a vehicle body frame located in front of an axle of a front wheel in a lateral width of the left and right frames. The actuator part of the steering device is arranged vertically and pivotally with the pitman arm as the front fulcrum, and the pitman arm and the knuckle arm of the front wheel are interlockingly connected through a tie rod. The actuator part of the steering device is arranged in a state of being positioned within the vertical width of the vehicle body frame, and the pitman arm is arranged below the lower end of the vehicle body frame.

A second characteristic configuration of the present invention is that the actuator portion of the power steering device is obliquely arranged with respect to the vehicle body frame and fixed in two directions, ie, the front-rear direction and the left-right direction.

[0007]

According to the first characteristic construction of the present invention, since the front wheel can be steered from the front of the front wheel via the pitman arm, the front wheel does not come into contact with the steering mechanism during steering operation, and The cutting angle can be increased.

Further, since the actuator portion of the power steering device is arranged in the space surrounded by the vehicle body frame, it is possible to avoid the actuator portion from coming into contact with another object.

Further, since the actuator portion of the power steering device is arranged within the vertical width of the vehicle body frame and the pitman arm is arranged below the lower end of the vehicle body frame, for example, the pitman arm is arranged within the vertical width of the vehicle body frame. Compared with the case where the actuator part of the power steering device is arranged below the lower end of the vehicle body frame, the notch formed on the side surface of the vehicle body frame, that is, the tie rod that interlocks and connects the pitman arm and the front knuckle arm The notch part to be inserted can be made small.

That is, in the case where the pitman arm is arranged within the vertical width of the vehicle body frame, the pitman arm extended to increase the cutting angle of the front wheel is extended along with the swing of the vehicle body frame. In order to avoid this, a notch portion is formed on the side surface of the vehicle body frame, but this notch portion becomes long in the front-rear direction. However, when the pitman arm is arranged below the lower end of the frame, the notch formed on the side surface of the frame is a small notch sufficient for inserting the tie rod that interlocks and connects the pitman arm and the knuckle arm of the front wheel.

According to the second characteristic configuration of the present invention, the actuator portion of the power steering device is obliquely arranged with respect to the vehicle body frame, and is attached to a corner of the vehicle body frame so as to be in two directions, ie, a front-rear direction and a left-right direction. Therefore, it can be firmly fixed and supported.

[0012]

According to the first characteristic configuration of the present invention, the front wheel does not come into contact with a part of the power steering device during the steering operation of the front wheel, and the cutting angle of the front wheel can be increased. By disposing the actuator portion of the power steering device in the space surrounded by the vehicle body frame, it is possible to avoid the actuator portion from coming into contact with another object. In addition, by disposing the pitman arm below the lower end of the vehicle body frame, the cutting angle of the front wheels can be increased without lowering the strength of the vehicle body frame.

According to the second characteristic configuration of the present invention, the actuator portion of the power steering device disposed in the vehicle body frame can be firmly supported with respect to the vehicle body frame from two directions of front and rear and left and right. Support strength of the part is improved.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to a power steering device for front wheels of a tractor.

FIG. 1 shows the entire tractor. In this tractor, a vehicle body frame is a monocoque in which a clutch housing 3 directly connected to an engine 2 and a transmission case 5 at the rear of the machine body are connected by a tubular transmission case 4 made of sheet metal. A battery 5 and a radiator 6 are mounted on a frame 1 as a vehicle body frame which is composed of a body and extends forward from the engine 2. Below the frame 1, an axle case 6 for front wheels 6 is mounted.
A is mounted around the front and rear axis P so as to be freely rotatable.

The front wheels 6 are driven via an integral type power steering device S, and are mounted on the frame 1 in front of the axle 6a of the front wheels 6, as shown in FIGS.
As shown in FIG. 3, the pitman arm 7 in a state of being positioned within the lateral width of the frame 1 and the controller 8 as an actuator section of the power steering device that drives the pitman arm, that is, a controller in which a valve and a cylinder are integrally configured. 8, controller 8 is frame 1
And the pitman arm 7 is positioned below the lower end of the frame 1 while being positioned within the vertical width of the frame 1, and further, the pitman arm 7 is swingably arranged left and right with the front fulcrum a as the front fulcrum a. The worm shaft 8a, which is a rotating shaft of the steering wheel 8, and the rotating shaft 9a of the handlebar 9 are interlockingly connected through a joint shaft 10, and the pitman arm 7 and the knuckle arms 11 and 11 of the left and right front wheels 6 and 6 are tie rods, respectively. 12 and 12 are interlockingly connected.

The controller 8 is arranged in an inclined posture of 40 degrees with respect to the center line of the frame 1 along the front-rear direction, and is bolted to the frame 1 from two directions, the front-rear direction and the left-right direction. It is fixed.

That is, the boss portions 8b and 8b provided on the controller 8 are applied to the reinforcing frame 1b for reinforcing and connecting the left and right frame portions 1a and 1a and one frame portion 1a of the left and right frame portions 1a and 1a. It is attached and fixed through two bolts 13, 13 from the front-rear direction and the left-right direction.

On the side surface of the frame 1, there is provided a small notch 1c for inserting a tie rod 12 for interlockingly connecting the pitman arm 7 and the knuckle arm 11 of the front wheel.

[Other Embodiments] The power steering device may be of the full hydraulic type.

The body frame may be a frame type body.

The work vehicle may be a riding lawn mower.

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 configuration of the accompanying drawings by the entry.

[Brief description of drawings]

FIG. 1 is a schematic side view of a tractor.

FIG. 2 is a plan view of a steering device.

FIG. 3 is a side view of the same.

[Explanation of symbols]

 1 Body Frame 6 Front Wheel 6a Axle 7 Pitman Arm 8 Actuator 11 Knuckle Arm 12 Tie Rod a Front Support S Power Steering Device

Claims (2)

[Claims] 1. A work vehicle for driving a pair of left and right front wheels via a power steering device, wherein a left and right frame portion (1) is attached to a vehicle body frame (1) in front of an axle (6a) of the front wheels (6). ), The actuator portion (8) of the power steering device (S) for driving the pitman arm (7) and the pitman arm (7) is vertically moved, and the pitman arm (7) is a front fulcrum ( a)
The pitman arm (7) and the knuckle arm (1) of the front wheel (6) are arranged so as to be swingable left and right.
1) and (11) are interlockingly connected to each other via tie rods (12) and (12), and further, the actuator portion (8) of the power steering device (S) is connected to the vehicle body frame (1).
A power steering structure for a working vehicle in which the pitman arm (7) is disposed below the lower end of the vehicle body frame (1) while being disposed in the vertical width of the vehicle body. 2. The actuator section (8) of the power steering device (S) is obliquely arranged with respect to the vehicle body frame (1) and is fixed in two directions, a front-rear direction and a left-right direction. The steering structure of the work vehicle described in.