JPH029970B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention provides a pair of left and right front wheels that can be steered freely, and a pair of left and right rear wheels that cannot be steered. A first state in which transmission is performed such that the average circumferential speed and the average circumferential speed of the pair of said rear wheels are the same or almost the same, and the average circumferential speed of the pair of said front wheels is greater than the average circumferential speed of the pair of said rear wheels. The present invention relates to a driving operation structure for an agricultural tractor provided with a front wheel transmission that can be switched freely to a second state in which transmission is performed at an increased speed.

[Conventional technology]

In the agricultural tractor described above, conventionally, [] the front wheel transmission changes from one of the first state and the second state as the front wheels are steered or one of the brake pedals is depressed. The front wheel transmission is linked to a steering operating device or a brake pedal so that the transmission can be automatically switched to the other. (For example, see Japanese Patent Application Laid-Open No. 53-47631.) [] A continuously variable transmission is provided in the front wheel drive system, and in conjunction with the steering operation of the steering system, the speed of the front wheels is increased steplessly when turning. (For example, see Japanese Unexamined Patent Publication No. 58-211923.) The techniques shown in [] and [] above were known.

[Problem that the invention seeks to solve]

However, the conventional techniques described in [] and [] above have the following problems.

[B] Considering the prior art described in [] above, it is generally necessary to turn while increasing the speed of the front wheels to reduce the area where the headland is disturbed by turning the aircraft, and to In order to widen the range in which the intended work can be carried out effectively, it is necessary for the tractor to make sharp turns with the front wheels increased when traveling on general roads or farm roads during so-called work in the field. In fact, from a safety perspective, there was a problem in that the front wheels suddenly accelerated during steering, causing a delay in returning the steering wheel, which could lead to unexpected accidents.

[B] Also, considering the prior art described in [] above, in this prior art, the speed increase rate is gradually increased in conjunction with the steering operation from going straight to turning. Therefore, it is advantageous in that it is possible to avoid the inconvenience caused by sudden speed increase as in the case [] above, but on the other hand, the structure of the front wheel transmission itself becomes complicated because it is equipped with a continuously variable transmission. However, there was an unavoidable disadvantage in terms of transmission efficiency.

In order to solve the problems in [a] and [b] above, a means for artificially switching between a state in which the front wheels are allowed to accelerate and a state in which they are not allowed to be increased is added to the prior art described in [] above. Although it is not unthinkable to provide a switch, in this case, there is a new problem of unexpected operation due to forgetting to switch.

The purpose of the present invention is to make it possible to sufficiently reduce the headland area and sufficiently improve work efficiency, and also to enable safe driving on the road, to have a simple structure, good transmission efficiency, and to avoid forgetting operations. An object of the present invention is to provide a running operation structure for an agricultural tractor that can speed up the front wheels without any trouble.

[Means to solve the problem]

The characteristic configuration of the present invention for achieving the above object is that, in the above-mentioned operating structure for running an agricultural tractor, a steering state in which the steering angles from the straight-ahead state to the leftward and rightward directions are less than about 40 degrees is provided. When the front wheel is present, the front wheel transmission is in the first state, and when the front wheel is steered from the straight-ahead state to a state in which it swings leftward and rightward by approximately 40 degrees or more, the front wheel In order to automatically switch the front wheel transmission to the second state, a linkage mechanism is provided that links the steering operation device of the steering wheel and the front wheel transmission, and its operation and effect are as follows. It is as follows.

[Operation] Even if the front wheels are steered, if the steering angle is smaller than approximately 40 degrees, the front wheel transmission is in the first state due to the linkage mechanism, and the front wheels are maintained in a non-speed increasing state. When the front wheels are steered so that the steering angle is approximately 40 degrees or more, the front wheel transmission automatically switches to the second state due to the linkage mechanism, and the front wheels are in the increased speed driving state. It becomes.

The maximum steering angle of this type of agricultural tractor is approximately 55 degrees, and the need for the machine to turn around this maximum steering angle is when making an interlining turn on the headland of a field, etc. The steering angle, which is limited to turning during work and is operated while an agricultural tractor is traveling at a certain speed on general roads or farm roads, is approximately
Normally, the steering angle is less than 30 degrees, and on general roads, agricultural tractors are steered within a range close to the maximum steering angle of 40 degrees or more when entering a garage, where the tractor is operated with the machine almost stationary. limited to cases such as Therefore, even if no special front wheel increase check means is used, the front wheels will not suddenly increase speed while driving at high speed.

[Effects of the Invention] Due to the above-mentioned effects, although the front wheels are increased in speed in order to reduce the headland area and improve work efficiency, it is possible to increase the speed of the aircraft while running at high speed on the road where there is no need to increase the speed of the front wheels. Sharp turns can be avoided without requiring a special restraint structure.

Due to the above-mentioned effect, there is no need to perform an operation to check or release a sharp turn of the aircraft while traveling at high speed, and there is no risk of unexpected operation due to forgetting to perform the operation.

Due to the above-mentioned effects, smooth speed increase of the front wheels can be performed without requiring a continuously variable transmission, so that the structure does not become complicated or the transmission efficiency decreases due to the use of a continuously variable transmission.

〔Example〕

As shown in FIG. 8, a pair of left and right front wheels 1a,
1b that can be steered and driven, and a pair of left and right non-steering type rear wheels 2a, 2b that can be driven, and various working devices such as a rotary tiller can be operated up and down. The agricultural tractor is equipped with a lift arm 3 that can be freely connected and a power take-off shaft 4 that transmits power to a connecting work device.

A front wheel transmission 15 located between a traveling transmission (not shown) and the front wheels 1a and 1b is installed at the front end of the transmission case 14 forming the rear part of the traveling body. , this transmission 15 is constructed as shown in FIGS. 2 to 4.

That is, a standard speed transmission gear 18 is interlocked with a front wheel output gear 16 of a traveling transmission case (not shown) via a gear 17 and is provided with a clutch pawl portion 18a; Each of the speed increasing transmission gears 22, which are interlocked via a gear 20 and equipped with a multi-plate friction clutch 21, is attached to an output shaft 23 so as to be relatively rotatable. Transmission member 25 that can be used for both transmission and transmission
is installed.

Then, by sliding the shifter 26 which is slidably attached to the transmission case 14 via a support shaft 27, the transmission member 25 is slid, and the transmission member 25 engages and disengages from the clutch pawl 18a. Standard speed transmission gear 18 with possible clutch pawl 25a
When engaged rotatably with the front wheels 1, the pair of front wheels 1
Average circumferential speed of wheels a and 1b and pair of rear wheels 2a and 2b
The transmission member 25 enters the first transmission state in which the transmission is transmitted to the front wheel differential mechanism 28 so that the average peripheral speed of
When the pair of rear wheels 2a and 2b are released from the friction clutch 21 and the friction clutch 21 is in a non-acting state,
Only the front wheels 1a, 1b are driven, and the pair of front wheels 1a, 1b are in an idle state, resulting in a neutral state in which the transmission to the front wheels 1a, 1b is cut off, and the transmission member 25 is moved by the transmission section 25b to engage the friction clutch 21. When the operation is performed to rotate integrally with the speed-increasing transmission gear 22, the average circumferential speed of the pair of front wheels 1a, 1b is made larger than the average circumferential speed of the pair of rear wheels 2a, 2b, and the The second transmission state is set in which speed-up transmission is performed to the front wheel differential mechanism 28 so that the front wheel drive speed is approximately twice as high as in the first transmission state.

A swinging arm 29 whose free end is engaged with the shifter 26, an interlocking tool 31 which is interlocked with the shifter 26 via a rotary cylinder shaft 30 penetrating through the mission case 14, and screwed onto the mission case 14. A spring 33 as shown in FIG. 4 attached across the bolt 32 urges the transmission 15 to the first transmission state. The swinging arm 29, the rotating cylinder shaft 30, the interlocking tool 31, the rotating shaft 34 that passes through the rotating cylinder shaft 30 and the transmission case 14 so as to be able to rotate relative to each other, and the swinging arm 3.
6. Tie rods 7 are attached to the release wire 37, the spring 39, the swinging arm 41 which is attached to the front wheel mounting frame 40 of the traveling aircraft so as to swing around the axis _P3 , the cam mechanism 42, and the front wheel knuckle arm 13. Interlocked Pittman arm 1
1 and the interlocking mechanism 6 between the pitman arm 11 and the steering handle 5, respectively, constitute an interlocking mechanism 43 between the steering handle 5 and the transmission 15, so that the rotation of the front wheels 1a, 1b by rotation of the steering handle 5 is performed. As the steering operation is performed, the transmission 15 is automatically switched as follows. That is, the cam mechanism 4
2 is a pittman arm 1 as shown in FIG.
1, a cam groove 45 formed by a cam plate 44;
The roller 47 is attached to the swing arm 41 via a support shaft 46 so as to swing together, and is fitted into the cam groove 45.As shown by the solid line in FIG. When the Pitman arm 11 is in the set swing range L with the neutral position A where the wheels 1a and 1b are in the straight-ahead state N being an intermediate position,
As the inner portion 45a of the cam groove 45 acts on the roller 47, the transmission 15 is in the first transmission state, and as shown by the imaginary line in FIG.
When the Pitman arm 11 swings to the left or right side of the machine beyond the set swing range L, the outer portion 45b or 45c of the cam groove 45 moves against the roller 47.
, and the transmission 15 is configured to switch to the second transmission state. One limit l of the setting range L is such that the front wheels 1a and 1b are at a position a when they are swung leftward by about 40 degrees (37 degrees to 43 degrees) from the straight-ahead state N, and the other limit is r is set to position b, where the front wheels 1a and 1B are swung approximately 40° (37° to 43°) to the right from the straight-ahead state N; Angle C up to steering limit E ₁ , and
Angle d from straight-ahead state N to rightward steering limit E ₂
are set at approximately 55°. In other words, the switching steering angle between the first state and the second state is set to approximately 40 degrees, and the steering angle from the straight-ahead state N to the left and right is less than approximately 40 degrees. When the front wheels 1a and 1b are in the direction state, the transmission 15 is in the first transmission state, and the front wheels are in a state in which they swing from the straight-ahead state N to the left by about 40 degrees or more and to the right by about 40 degrees or more. When 1a and 1b are steered, the transmission 15 is automatically switched to the second transmission state.

The interlocking tool 31 is configured to slide with respect to the rotary cylinder shaft 30 for spline engagement, and
With this sliding movement, it is configured to engage with the rotating shaft 34 so as to be able to rotate integrally with it, and to be able to separate from it so that it can rotate relative to it. As shown in FIGS. 3 and 5, a support shaft 48 is attached to the mission case 14.
and the first axis P ₄ and the first axis via the fixture 49
The interlocking tool operating members ₅₀ are mounted so as to swing around the respective axes P5, and the operating levers 51 are attached to the mounting fixtures 49 together with the operating members 50 around the first axes _P4 relative to the mission case 14. The operating arm portion 5 of the interlocking tool operating member 50 is slidably inserted into the cylindrical body 52 that is connected so as to swing.
0a so as to be relatively swingable, and the transmission device 15 and the linking mechanism 43 are switched by rotating and sliding the interlocking tool 31 by manual operation of the operating lever 51. be.
That is, as the operating lever 51 is raised and lowered along the vertical groove portion 55a of the guide groove 55 formed in the guide 54 for the operating lever 51 so as to act on the projection 51a of the operating lever 51, the interlocking tool is operated. The horizontal groove portion 5 of the guide groove 55 is configured such that the member 50 swings around the second axis P ₅ and slides the interlocking tool 31 with respect to the rotating cylinder shaft 30 .
5b, the interlocking tool operating member 50 swings around the first axis _P4 to press and rotate the interlocking tool 31, and the interlocking tool 31 moves against the spring 33. It is designed to allow rotational operation by the operator. More specifically, when the operating lever 51 is operated to the first operating position 4WD, the interlocking tool 31 engages with the rotating shaft 34 and the linking mechanism 43 becomes linked, and the switching operation of the shifter 26 by the pitman arm 11 is prevented. When the interlock operating member 50 is moved to the permissible position, the transmission 15 can be switched between the first transmission state and the second transmission state by the Pitman arm 11. Then, when the operating lever 51 is operated to the second operating position 4WD, the interlocking tool 31
is detached from the rotating shaft 34 and the linkage mechanism 43 becomes unlinked, and the shifter 26 is moved away from the spring 3
3, the transmission 15 enters the first transmission state. And the operation lever 51
When operated to the third operation position 2WD, the interlocking tool 31
is detached from the rotating shaft 34 and the linkage mechanism 43 becomes unlinked, and the shifter 26 is moved away from the spring 3
The interlocking tool operating member 50 presses the interlocking tool 31 so as to operate against the rotational speed 3, and the transmission 15 enters the neutral state.

As shown in FIG. 6, the hook-type stopper 56 that locks the operating lever 51 in the third operating position 2WD is moved so that the action portion 56a enters the movement path of the operating lever 51 and the positioning portion 56b is attached to the guide 54. The connecting pin 5 is placed between the working position where the working part 56a is in contact and the releasing position where the working part 56a is out of the moving path.
The guide 54 is pivotally connected to the guide 54 via the connecting pin 57 so as to swing around the axis 7. The spring 5 fitted onto the connecting pin 57
8 to urge the stopper 56 to the operating position, and to press the stopper 56 to the release position by the operating lever 51.
9 and an operating section 60 for manually operating the stopper 56 to the release position, and when the operating lever 51 is operated to the third operating position 2WD, the stopper 56
When the control lever 51 comes into contact with the operating lever 51, it automatically becomes the release position and allows the operating lever 51 to pass through, and when the operating lever 51 reaches the third operating position 2WD, it automatically returns to the operating position and the operating lever is closed. 51 is held at the third operating position 2WD, and when operating the operating lever 51 to the second operating position 4WD, the stopper 56 is manually released.

In short, when the operating lever 51 is operated to the first operating position 4WD, the average circumferential speed of the front wheels 1a, 1b and the average circumferential speed of the rear wheels 2a, 2b become the same or almost the same, and the front wheels 1a, 1b A four-wheel drive system in which both the front and rear wheels are driven while automatically changing gears in conjunction with the steering operation of the aircraft. state, and move the operating lever 51 to the second position.
When the operation position is set to 4WD, the front wheels 1a, 1
While maintaining the average circumferential speed of b and the average circumferential speed of the rear wheels 2a and 2b to be the same or almost the same regardless of the steering operation of the aircraft, a four-wheel drive state is entered in which both the front and rear wheels are driven. , operation lever 51
When operated to the third operating position 2WD, the rear wheel 2
It is in a two-wheel drive state in which only wheels a and 2b are driven.

The spring catch 61 shown in FIG. 6 is for holding the operating lever 51 in the first operating position 4WD and the second operating position 4WD.

The operating lever 51 is in the first operating position 4WD.
A detection switch 62 detects that the rotation speed of the output shaft 23 is higher than a set rotation speed, and a sensor 63 detects that the rotation speed of the output shaft 23 exceeds a set rotation speed. Then, as shown in FIG. 7, the detection switch 62 and sensor 63 are linked to the indicator lamp 64 and the steering horn 65, and when the detection switch 62 enters the detection state, the indicator lamp 64 is automatically turned on. Additionally, when both the detection switch 62 and sensor 63 are in the detection state, the driving horn 65 is configured to operate automatically, and when the front wheels are operated to enable automatic gear shifting, the indicator lamp 64 lights up. It is displayed by lighting, and a warning is given using the driving horn 65 when the front wheels 1a, 1b are in an increased speed state while driving on the road.

[Another example]

As the transmission for the front wheels, one having a transmission means that is operated by hydraulic pressure may be adopted.

In order to link the steering operation device of the steering wheel and the transmission device for the front wheels, electric means may be used in addition to mechanical means.

[Brief explanation of drawings]

The drawings show an embodiment of the operation structure for running an agricultural tractor according to the present invention, in which Fig. 1 is a plan view of the cam mechanism, Fig. 2 is a partially cutaway side view of the front wheel transmission, and Fig. 3 is the front wheel transmission. Fig. 4 is a partially cutaway front view of the transmission for the
The drawings are a sectional view taken along the line -- of FIG. 3, FIG. 6 is a plan view of the lever stopper, FIG. 7 is an electric circuit diagram, and FIG. 8 is a partially cutaway side view of the entire agricultural tractor. 1a, 1b...front wheels, 2a, 2b...rear wheels, 5...steering handle, 15...front wheel transmission, 43...coupling mechanism.

Claims (1)

[Claims] 1. A pair of left and right front wheels 1a, 1b can be freely steered,
In addition, the pair of left and right rear wheels 2a, 2b are provided so that they cannot be steered, and the average circumferential speed of the pair of front wheels 1a, 1b is the same or almost the same as the average circumferential speed of the pair of rear wheels 2a, 2b. a first state in which transmission is performed so that The operating structure for running an agricultural tractor is provided with a switchable front wheel transmission 15, in which the front wheels 1a are in a steering state in which the steering angle from a straight-ahead state to leftward and rightward directions is less than about 40°. , 1b, the front wheel transmission 15 is in the first state, and the front wheel transmission 15 is in the first state, and the front wheel transmission 15 is turned leftward and rightward from the straight-ahead state.
A steering operation device of the steering handle 5 is configured such that when the front wheels 1a, 1b are steered to a state in which they are swung by 40 degrees or more, the front wheel transmission 15 is automatically switched to the second state. A driving operation structure for an agricultural tractor, which is provided with a linkage mechanism 43 linked to the front wheel transmission 15.