JPH0241935A - Steering operation structure of agricultural vehicles - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention comprises a standard drive clutch 9 that is configured so that only the front wheels can be steered and that drives the front wheels at approximately the same speed as the rear wheels; A front wheel transmission is provided that can selectively switch between a friction clutch for increasing the speed of the front wheels that is driven at a higher speed than the front wheels, and a linking member whose displacement is operated by steering the front wheels by a predetermined amount or more, and switching between the front wheel transmission and the front wheel transmission. The agricultural vehicle is connected to an operating member via a stroke absorbing spring, and is configured to switch from the engaged state of the standard drive clutch to the engaged state of the front wheel speed increasing friction clutch by displacement operation of the linking member. Regarding steering operation structure.

[Conventional technology]

As the conventional operation structure, for example, Japanese Patent Application Laid-open No. 6
As shown in Japanese Patent No. 3-34229, the linking member and the front wheel transmission are interlocked only through the operating wire and the stroke absorbing spring.

[Problem to be solved by the invention]

The spring transmits the displacement of the linking member due to steering of the front wheels at a setting of 1 or more to the front wheel transmission, engages and operates the front wheel speed increasing friction clutch, and absorbs a displacement of the linking member that is more than necessary. The spring force is set to a large value in order to increase the accuracy of the linkage.

However, since this linkage structure uses only a spring with a large spring force, when the front wheels are rotated over a set distance, the friction clutch is rapidly engaged and activated, causing the front wheels to suddenly shift from the standard state to the increased speed state. Will have to switch. As a result, the front wheels suddenly accelerate while the aircraft is turning, causing problems such as mud splashing in paddy fields and pushing down grass in grassy areas.

An object of the present invention is to eliminate the above-mentioned disadvantages.

The object of the present invention is to provide a steering operation structure for an agricultural vehicle that allows smooth turning.

[Means to solve the problem]

A feature of the present invention is that in the steering operation structure for an agricultural vehicle having the above configuration, during the linkage between the linking member and the switching member, the relative displacement of the predetermined platform is made weaker than the elastic force of the spring. An elastic accommodating mechanism is provided to provide elasticity, and its functions and effects are as follows.

[For production]

That is, when the front wheels are steered by a set amount, the linking member starts to be displaced. At this time, the switching operation member receives a displacement operation force of only the elastic force of the elastic accommodation mechanism, resulting in a half-clutch state in which friction is transmitted with a weak force. The clutch is engaged with a strong force via the spring due to the displacement of the predetermined amount or more, and
Displacement of the linking member in excess of the required amount is absorbed by the expansion of the spring.

〔Effect of the invention〕

Therefore, according to the present invention, when switching from the standard drive state to the front wheel speed increase state, the half-clutch state appears only within a predetermined steering range, and the front wheel speed increase state is set for steering beyond that range. This eliminates sudden drive switching when the aircraft turns.
It is possible to turn smoothly. As a result, it was possible to eliminate the risk of mud splashing, grass being pushed over, etc.

Further, it is conceivable to use an electric detection means and a control means to achieve the above-mentioned effect, but this has the disadvantage that the structure becomes complicated and the cost increases. It is sufficient to simply add , and the structure does not become complicated.

〔Example〕

Embodiments of the present invention will be described below based on the drawings.

FIG. 5 shows an agricultural tractor which is an example of an agricultural vehicle according to the present invention. This agricultural tractor is equipped with a pair of left and right wheels (1), (2) at the front and rear, and is constructed such that only the front wheels (1), (1) can be steered using a steering handle (3). 1) and (2) are configured to be driven to travel. And the front wheel (
1), the standard condition where (1) is driven at approximately constant speed with the rear wheels (2), (2), and the front wheels (1), (1) are driven with the rear wheels (2),
A front wheel transmission (4) is provided which can switch to a front wheel speed increasing state in which the front wheels are driven at a higher speed than (2).

The front wheel speed increasing device (4) is constructed as shown in FIG. In other words, a small-diameter gear (7) that is always engaged with the transmission gear (6) inside the mission case (5) is fitted around the rotating shaft (8) with a spline, and a standard drive gear (9) that is engaged with this gear (7). is loosely fitted onto the output shaft (10) for the front wheels (1), (1), and a gear portion (12a) in which a large diameter gear (11) fitted externally with a spline on the rotating shaft (8) engages. The formed rotating drum (12) is fitted around the output shaft (10) for free rotation. And between the standard drive gear (9) and the rotating drum (12), the output shaft (10) has a
A shift member (13) that can be integrally rotated and freely shifted in the axial direction is fitted onto the outside, and a claw clutch (14) as a standard drive clutch is fitted between the shift member (13) and the standard drive gear (9). ) is configured. On the other hand, a multi-disc friction clutch (16) is provided between the rotating drum (12) and an inner shaft (15) that is spline-fitted on the output shaft (10) inside the rotary drum (12). Then, the shift member (
13) with the standard drive gear (9), it is possible to set the standard drive state in which the peripheral speeds of the front and rear wheels (1) and (2) are at -road speed, and also to disengage the pawl clutch (14). At the same time, by pressing the friction clutch (16) with the shift member (13) to engage the clutch,
The configuration is such that a front wheel speed increase state can be created in which the circumferential speed of the front wheels is set higher than the circumferential speed of the rear wheels.

Then, move the front wheels (1) and (1) approximately 4
When the vehicle is steered to either the left or right by 0 degrees, the standard driving state is automatically switched to the front wheel speed increasing state. To be more specific, as shown in Fig. 1, a fixed cam plate (18) is provided on the pitman arm (17) that swings around the vertical axis in conjunction with the turning operation of the steering handle (3), and a side A swinging arm (19) serving as a linking member swinging around the vertical axis (P) of the cam plate (18) is provided in duplicate. A cam groove (21) is formed in the cam plate (18) with a pin (20) protruding from the swing arm (19).
When the pitman arm (17) swings left and right by more than a predetermined angle from the straight-ahead state, the pin (20) is guided by the cam groove (21) and the swing arm (19) swings forward. It is configured to work. And the swing arm (19
) and a shift fork (22) acting as a switching operation member for operating the shift by acting on the shift member (13) via a rod (23) and a stroke absorbing spring (24). They are interlocked. In order to ensure that the friction clutch (16) is engaged, this spring (24) is designed to increase the amount of rod pulling operation associated with the swinging of the swinging arm (19) than the amount of operating displacement of the shift fork (22>). Since it is set, it is intended to absorb the stroke.

An elastic accommodation mechanism allows a predetermined amount of relative displacement between the swing arm (19) and the shift fork (22) with an elastic force weaker than the elastic force of the spring (24). (25) is inserted. More specifically, as shown in FIG. 2, the end of the rod (23) is bent and formed, and an engagement member (27) is provided in which a long hole (26) into which the bent portion engages is formed. The negative end of this engaging member (27) and the shift fork (22Hf)
i-action arm (28) and said spring (24).
are connected. Then, a flexible spring (29) whose spring force is set to be weaker than that of the spring (24) is stretched across the bent part of the rod (23) and the inner surface of the elongated hole (26) on the side where the spring (24) is stretched. It has been done.

With this configuration, as shown by the solid line (L) in FIG. 3, the rod (
At the beginning of switching, the change in the pressing force (Y) of the friction clutch (16) with respect to the pulling operation displacement amount (X) of 23) is a gradual change due to the flexibility spring (29), and in this region (S), the clutch is half-closed. A state emerges. When the rod (23) reaches the end of the elongated hole (26), it is pulled by the strong spring (24), so that the friction clutch (16) is reliably engaged and operated. Therefore, compared to the case where only the stroke absorbing spring (24) having the characteristics shown by the dotted line <7) in FIG. 3 is linked, the aircraft can turn smoothly.

[Another example]

As shown in FIG. 6, the elastic accommodation mechanism (25) is attached to the stroke absorbing spring (
24> and the flexible spring (29), and a spring receiving plate (24) integrally formed with the rod (23) is provided before and after
31a), (31b) are externally inserted so as to be relatively movable, and a relay shaft member (30
) may be provided with a fixed partition (32) so that the flexible spring (29) begins to compress as the rod (23) is displaced.

Incidentally, although reference numerals are written in the claims section for convenient comparison with the drawings, the present invention is not limited to the structure shown in the accompanying drawings.

[Brief explanation of the drawing]

The drawings show an embodiment of the steering operation structure for an agricultural vehicle according to the present invention, FIG. 1 is a system diagram showing the linkage structure, FIG. 2 is a plan view of the main parts, and FIG. FIG. 4 is a sectional view of the front wheel transmission, FIG. 5 is a side view of the entire agricultural tractor, and FIG. 6 is a plan view of the main parts of another embodiment. (1), (1)...Front wheel, (2), (2)...
...Rear wheel, (4) ...Front wheel transmission, (
14)...Clutch, (16)...Friction clutch, (22)...Switching operation member, (2
4) Spring, (25) Elastic flexibility mechanism.

Claims (1)

[Claims] A standard drive clutch (14) configured so that only the front wheels (1), (1) can be steered and drives the front wheels (1), (1) at approximately the same speed as the rear wheels (2), (2). and front wheels (1), (1
) and a friction clutch (16) for increasing the speed of the front wheels, which drives the rear wheels (2) at a higher speed than the rear wheels (2), (2). ) is connected to the switching member (22) of the front wheel transmission (4) via a stroke absorbing spring (24), and the linking member (19) is operated to be displaced by steering by a preset amount or more. The standard drive clutch (
14) is engaged, the front wheel speed increasing friction clutch (1
6) A steering operation structure for an agricultural vehicle configured to switch to the on state, wherein a predetermined amount of relative displacement occurs during the linkage between the linking member (19) and the switching member (22). A steering operation structure for an agricultural vehicle, which is provided with an elastic accommodation mechanism (25) that allows the above-mentioned movement with an elastic force weaker than the elastic force of the spring (24).