JPH07277215A - Steering device - Google Patents

Abstract

PURPOSE:To set up the turning angle of a wheel large with search for the form of Ackermann jeantaud by providing a connecting arm to interlockingly connect right and left relay arms to each other for composing a four-train link mechanism. CONSTITUTION:The connecting rod pivotally supporting point Q of a knuckle arm 6 is arranged nearer outsides in directions right and left to a machine body than the pivotally attaching point P of right and left knuckle arms 6, 6 to a front axile case, and a pair of right and left relay arms 88 being oscillatable around upward oscillating supports X, X are arrangedly provided between right and left knuckle arms 6, 6. The relay arms 8, 8 are arranged in a state where they are extended along the front (in a direction leaving for the connecting rod pivotally supporting point Q from the pivotally attaching point P), and the right and left relay arms 8, 8 are mutually interlockingly connected with a connecting arm 10 so as to turn to the same direction for composing a four-train parallel link mechanism B. Thus the steering device by which the maximum turning angle of a steering wheel can be enlarged with search for Ackermann Jeantaud theory can be obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a steering device in which the steering angle of a wheel on the inside of a turn associated with a turning operation is larger than the steering angle of a wheel on the outside of a turn, that is, a steering device incorporating the so-called Ackermann-Junt theory. In particular, the present invention relates to a technique for increasing the maximum turning angle of a wheel. The present invention is also applicable to work machines such as tractors and lawnmowers, industrial vehicles such as forklifts and trucks, or automobiles.

[0002]

2. Description of the Related Art For example, as in a steering device for a tractor disclosed in Japanese Patent Laid-Open No. 3-208774, Ackermann-Junt theory is adopted as a structure for connecting left and right knuckle arms with a single straight tie rod. There is something.
In this structure, the pivot point between the knuckle arm and the tie rod (reference numeral 26) is closer to the outside in the lateral direction of the machine than the pivot point between the knuckle arm (reference numeral 25) and the front axle case (reference numeral 24). There is a feature that they are placed in different positions.

[0003]

Therefore, in the steering apparatus having the above structure, the tie rod and the axle case tend to come into contact with each other relatively easily due to the steering operation of the wheels, and the maximum turning angle is set to a large value. About is a disadvantage.

Therefore, there is a means for increasing the wheel turning angle by increasing the front-rear distance between the tie rod and the front axle case, as in the tractor disclosed in Japanese Patent Application Laid-Open No. 5-65071. However, with this means, the knuckle arm is greatly extended forward, the hub portion supporting the steered wheels is enlarged, and the degree of freedom in the layout of the brake device and its piping is reduced. Has a disadvantage in that it is difficult to increase the size of the knuckle arm itself due to the arrangement space, and the swing space of the knuckle arm becomes large and the movement space of the tie rod also becomes large. There are necessary disadvantages.

It is an object of the present invention to adopt the form of the Ackermann-Junt theory, and to reduce the space required for the operation of the steering device without unnecessarily increasing the size of the knuckle arm and to obtain a large wheel turning angle. The point is to get the device.

[0006]

In order to achieve the above-mentioned object, the present invention provides a tie rod pivot point of each knuckle arm in the left-right direction with respect to the machine body, rather than a pivot point of each left and right knuckle arm to a device fixing portion. A pair of left and right relay arms that are arranged close to the outside and that can swing around a fulcrum located between the left and right knuckle arms are provided, and these relay arms extend along the direction from the pivot point to the tie rod pivot point. The left tie rod, which is arranged in a state of being taken out, forms a four-link mechanism by providing a connecting arm that interlocks and connects the left and right relay arms, and interlocks and connects the tip of the left relay arm and the left tie rod pivot. The steering device is characterized in that a right tie rod for interlockingly connecting the tip of the right relay arm and the right tie rod pivot is provided.

[0007]

For example, as in the comparative example shown in FIG. 3, the tip of the swing arm 8 and the left and right knuckle arms 6 provided at the left and right centers.
The respective 6 ties are interlockingly connected by different tie rods 9, 9, and the tie rods 9 are obliquely connected to the knuckle arm 6 for pivotal support, thereby increasing the maximum turning angle of the front wheel 1 when hitting the front axle case 7. It is possible. Certainly, although the cutting angle itself can be increased by this means, since the tie rod 9 is obliquely arranged, the forward protruding length of the swing arm 8 is large, and a large space is still required for the swing movement thereof. The difference between the turning angle α of the turning inner front wheel 1 and the turning angle front β of the turning outer front wheel 1 (see FIG. 4) is also smaller than the difference required for the Ackermann-Jant form.

Therefore, in the steering apparatus of the present invention shown in FIG. 2, the swing arm 8 described above is replaced by a pair of left and right relay arms 8.
8 and the interlocking connection is made by the connecting arm 10, the length of the tie rod 9 can be made shorter than that of the comparative example, and the required turning angle of the steering wheel 1 can be obtained while the relay arm 8 The protruding length can be shortened. That is, it is possible to reduce the space required for moving the tie rod 9 and the relay arm 8 as compared with the comparative example technique while increasing the maximum cutting angle as compared with the conventional technique.

Further, since there are a pair of left and right relay arms 8, the flexibility of adjusting the operating characteristics of the quadruple link mechanism B is large by changing the position of the swing fulcrum X and the initial setting arrangement angle. . Therefore, it is easy to adopt the Ackermann junto form even if the specifications such as the wheelbase and tread are changed.

By the way, if the turning angle of the steering wheel is increased and the space required for the steering device is not increased, for example, a single tie rod bent and formed in a substantially trapezoidal shape is used. Means for providing may be considered. However, the steering wheel has alignment such as kingpin angle and caster angle, and the knuckle arm swings three-dimensionally, so the tie rod and knuckle arm are connected by a spherical joint such as a ball joint,
Therefore, the tie rod largely hangs down by its own weight in the free state. In the present invention, however, the relay arm that pivotally connects the tie rod ends simply swings to the left and right, so to speak, it is supported in the shape of a cantilever, so that the hanging of the tie rod is eliminated and a predetermined height is achieved. It also has the function of maintaining the position.

[0011]

As a result, the steering device capable of increasing the maximum turning angle of the steering wheel while adopting the Ackermann-Junt theory is adopted, and the space for disposing the steering device is also increased by adopting the four-link mechanism with the pair of left and right relay arms. It could be offered as a suppressed and reasonable one.

[0012]

Embodiments of the present invention will be described below with reference to the drawings. A tractor is shown in FIG. 1, 1 is a steering front wheel, 2 is a driving rear wheel, 3 is a driving part, 4 is a body frame, and 5 is a steering handle. This tractor employs an all-hydraulic power steering system.
The structure of the main part of will be described.

A steering apparatus A is shown in FIG. 2, 6 is a knuckle arm that supports the front wheel 1, 7 is a front axle case, 8 is a relay arm, 9 is a tie rod that connects the knuckle arm 6 and the relay arm 8. Reference numeral 10 is a connecting arm for connecting the left and right tie rods 9, 9 together. Incidentally, the front wheel 1 is also a driving wheel, and the front wheel is transmitted from the transmission shaft 11 for driving the front wheel through a differential mechanism (not shown) in the front axle case 7 and an interlocking mechanism (not shown) in the knuckle arm 6 part. It is transmitted to 1.

The steering structure will be described in detail. The front axle case of each of the left and right knuckle arms 6 and 6 (corresponding to the device fixing portion).
The tie rod pivot point Q of the knuckle arm 6 is arranged closer to the outside in the left-right direction with respect to the machine body than the pivot point P to
In addition, a pair of left and right relay arms 8, 8 that can swing around the upward swing fulcrums X, X are provided between the left and right knuckle arms 6, 6. These relay arms 8 and 8 are
Forward (direction from pivot point P to tie rod pivot point Q)
The parallel quadruple link mechanism B is configured by interlocking and connecting the left and right relay arms 8 and 8 with the connecting arm 10 so as to face in the same direction.

The left tie rod 9 connecting the tip of the left relay arm 8 and the left tie rod pivot point Q in an interlocking manner and the right tie rod 9 connecting the tip of the right relay arm 8 and the right tie rod pivot point Q in an interlocking manner are both left and right inside. The front wheels 1 are arranged in an oblique crossing toward the front and contribute to an increase in the maximum turning angle of the front wheel 1.

The pivot point P is actually three-dimensionally inclined by the caster angle, the kingpin angle, etc., and the vertical position of the tie rod pivot point Q moves up and down with the steering. On the other hand, each of the relay arms 8 and 8 has a simple rocking support structure in which the height level thereof does not change.
The knuckle arm 6 and the relay arm 8 are all connected via a spherical joint. However, the connecting arm 10
The relay arm 8 and the relay arm 8 have a simple pivotal connection structure.

In the steering apparatus A having the above-described structure, the turning angles of the left and right steering front wheels 1, 1 are fulcrum (P, Q, etc.) and arm lengths (relays) of each part in a state where the Ackermann-Junt theory is established. The arm 8 length, knuckle arm length, etc.) are set. For reference, FIG. 4 shows the turning principle based on Ackermann-Junt's theory. Briefly explaining, in a vehicle in which only the front wheels 1 and 1 are steered, the turning center Y is present on a straight line connecting the left and right rear wheels 2 and 2, and the turning angle α of the front inside wheel 1 is the front outside wheel. It is larger than the cutting angle β of 1.

Further, the front-back length of the tie rod pivot point Q and the pivot point P is short, and the knuckle arm 6 is compact in the front-rear direction, but the insides of the tie rods 9, 9 are inclined toward the front side. Therefore, the front wheel 1 can be deeply penetrated outside without hitting the front axle case 7 to increase the cutting angle of the front wheel 1, and the front-rear length of the relay arms 8 and 8 can be shortened by the action of the four-link mechanism B. It's done.

Incidentally, the swing fulcrum X of the right relay arm 8
A piston rod 14a of a double-acting hydraulic steering cylinder 14 is interlockingly coupled to an integrally swinging input piece 13 attached to the steering cylinder 14 and a controller 15 operated by a steering handle 5. , From the hydraulic pump 12, etc.,
An all-hydraulic power steering device C is configured.

[Other Embodiments] The positions of the left and right swing fulcrums X, X are set to the inner side, and the left and right relay arms 8, 8 are formed in an inverted C shape in which the front is open to the left and right outside, or the front is based on the inside. A four-link mechanism B having a regular C-shape may be configured, or the steering cylinder 14 may act on the tie rod 9 and the knuckle arm 6.

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

[Brief description of drawings]

FIG. 1 is a side view of a tractor.

FIG. 2 is a system diagram showing a steering device.

FIG. 3 is a plan view showing a comparative example of the steering device.

[Figure 4] Principle diagram showing Ackermann-Junt's theory

[Explanation of symbols]

 6 Knuckle arm 8 Relay arm 9 Tie rod 10 Connecting arm P Pivot point Q Tie rod pivot point X fulcrum point

Claims (1)

[Claims] 1. Tie rod pivots for the respective knuckle arms (6), (6) rather than pivot points (P), (P) of the left and right knuckle arms (6), (6) to the device fixing portions, respectively. The fulcrums (Q) and (Q) are arranged closer to the outside in the left-right direction with respect to the machine body, and can swing around the fulcrums (X) and (X) located between the left and right knuckle arms (6) and (6). A pair of right and left relay arms (8), (8) are provided, and these relay arms (8),
(8) is arranged so as to extend along the direction from the pivot point (P) to the tie rod pivot point (Q), and the left and right relay arms (8), (8) are interlocked with each other. A left tie rod (9) that interlocks and connects the tip of the left relay arm (8) and the left tie rod pivot (Q) by forming a four-link mechanism (B) by providing a connecting arm (10) for connecting. ,
And a right tie rod (9) for interlockingly connecting the tip of the right relay arm (8) and the right tie rod pivot (Q).