JPH0733970Y2 - Work vehicle steering structure - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to a front wheel steering structure in a working vehicle such as an agricultural tractor or a riding type rice transplanter.

[Conventional technology]

In an agricultural tractor which is one of the work vehicles, as disclosed in, for example, Japanese Patent Laid-Open No. 60-128077, a pitman arm extends from the power steering unit provided in the front axle case toward the front of the machine body. There is also a structure in which knuckle arms provided on the left and right front wheel support cases are extended to the front of the machine body, and tie rods are installed between the knuckle arms and the pitman arm to form a front wheel steering structure.

In this way, if one end of the tie rod is supported by the pitman arm, when one tie rod is bent forward over the left and right knuckle arms, the tie rod does not hang downward.

[Problems to be solved by the device]

If the work vehicle such as an agricultural tractor is particularly small,
The engine or mission case is arranged between the left and right front wheels. However, when the steering mechanism is arranged between the left and right front wheels as in the disclosed structure, the mounting position of the engine or the mission case also moves upward. As described above, the higher the mounting position of the engine or the mission case is, the higher the center of gravity of the entire machine body is, so that a problem remains in terms of traveling stability for a work vehicle traveling on a weak work site.

The present invention has been made in view of the above-mentioned problems, and an object thereof is to configure so that the center of gravity of the body can be lowered while preventing the tie rod from hanging downward. .

[Means for Solving the Problems]

A feature of the present invention is that the steering structure of the work vehicle as described above is configured as follows. In other words, a swingable arm around the axis of the vertical axis is provided between the pair of left and right front wheels, and tie rods are installed over the knuckle arms of the left and right front wheels and the swing end side of the arms. A steering mechanism is arranged further forward or rearward, and this steering mechanism and either the left or right front knuckle arm are linked and linked via a drag link, and the left and right tie rods intersect each other in a plan view near the arm. As described above, the connecting points for the arms of the left and right tie rods are arranged in the left-right direction.

[Action]

With the above-mentioned structure, the tie rod is prevented from hanging down by the supporting action of the arm, but since this arm simply swings in conjunction with the steering operation of the front wheels, the support of this arm is The structure may be simple, such as pins and brackets, and does not require a particularly large space. Then, the steering mechanism that requires a space is arranged in front of or behind the tie rod, and the drag link is arranged on one side of the left and right of the machine body.

Therefore, a relatively large space is obtained between the left and right front wheels, and a particularly large obstacle is eliminated. As a result, the engine or the mission case can be arranged so as to be dropped between the left and right front wheels.

Then, by crossing the left and right tie rods and connecting them to the arm, the steering angles of the left and right front wheels can be brought close to an ideal value. That is, in the two-wheel steering structure, since the turning center exists on the line connecting the rotation axes of the left and right non-steering wheels (rear wheels in the present application), the steering angle of the turning inside steered wheel is theoretically the turning angle. The steering angle of the outer steered wheels is larger than the steering angle, and the angle difference is larger as the turning radius is smaller.

For example, when the arm and the left and right tie rods are simply connected, the angular difference between the left and right steered wheels becomes smaller than the theoretical value as the steering angle increases, and the slippage of the inner or outer steered wheels becomes noticeable. Although there is a tendency, in the present invention with the tie rod cross arrangement, as the turning angle of the steering mechanism increases, the steering angle of the steering wheel on the inside of the turning increases more and the steering angle of the steering wheel on the outside of the turning increases. The steering angle can be made closer to the theoretical steering angle so that stable turning with less wheel slip can be obtained.

In other words, the rational arrangement of the arms and drag links has made it possible to simultaneously achieve the drop arrangement of the mechanical devices between the left and right front wheels and the appearance of a steering angle close to the ideal one.

[Effect of device]

As a result, it is possible to lower the position of the engine or the mission case while preventing the tie rod from hanging down, and the steering structure that improves the running stability of the work vehicle can realize a smoother and more stable turning state. I was able to realize it while making it available.

〔Example〕

Hereinafter, an embodiment of the present invention will be described with reference to the drawings by a riding type rice transplanter which is one of the working vehicles.

As shown in FIGS. 1 and 2, the engine (1) and the mission case (2) are arranged at the front of the machine body, and the front axle case (3) is extended from the mission case (2) to the left and right. A front wheel (4) is steerably supported on both ends of the steering wheel. As a result, the power of the engine (1) is transmitted to the front wheels (4) by a gear shift operation (not shown) in the transmission case (2) and is transmitted to the front wheels (4) and the rear wheels (via the transmission shaft (5)). It is transmitted to 6).

Next, the steering structure of the front wheel (4) will be described in detail. As shown in FIG. 1 and FIG. 2, the arm (7) is swingable around the lower axis (P ₁ ) of the lower portion of the mission case (2). ) Is attached. Then, the knuckle arm (8) of the front wheel (4) is extended forward, and a pair of tie rods (9) are laid across the left and right knuckle arms (8) and the central arm (7).

In this case, one tie rod (9) is connected to the upper surface of the arm (7) and the other tie rod (9) is connected to the lower surface of the arm (7), and both tie rods (9) are connected as shown in FIG. They intersect each other in a plan view. That is,
The left and right tie rods (9), (9) are connected to the respective arms (7) at the left and right connecting positions.

A steering mechanism (11) having a steering handle (10) is arranged on the upper front side of the mission case (2), and a swingable pitman arm (12) is slanted downward from the steering mechanism (11). A drag link (13) is extended from the pitman arm (12) and the one knuckle arm (8) by being extended.

It should be noted that reference numerals are added to the claims of the utility model for convenience of comparison with the drawings, but the present invention is not limited to the structure of the accompanying drawings by the entry.

[Brief description of drawings]

The drawings show an embodiment of the steering structure of a work vehicle according to the present invention. Fig. 1 is a vertical sectional side view of the front half of a riding type rice transplanter, and Fig. 2 is a plan view showing the steering structure of the front wheels of the riding type rice transplanter. FIG. 3 is a plan view showing a front wheel steering structure in another embodiment. (4) …… Front wheel, (7) …… Arm, (8) …… Knuckle arm, (9) …… Tie rod, (11) …… Steering mechanism, (13) …… Drag link, (P ₁ )… … Vertical axis.

Claims (1)

[Scope of utility model registration request] _1. An arm (7) swingable about a vertical axis (P ₁ ) is provided between a pair of left and right front wheels (4), (4), and the left and right front wheels (4), (4) are Knuckle arm (8),
Tie rods (9) and (9) are installed over (8) and the swing end side of the arm (7), respectively, and steering is performed forward or backward from the center of the left and right front wheels (4) and (4). The mechanism (11) is arranged, and the steering mechanism (11) and either one of the left and right knuckle arms (8) of the front wheels (4) are interlockingly connected via a drag link (13), and the arm (7) is connected. ), The connection points of the left and right tie rods (9), (9) with respect to the arm (7) are reversed so that the left and right tie rods (9), (9) intersect each other in a plan view. The steering structure of the work vehicle that is arranged.