JPH02290726A - Turning control device of tractor - Google Patents

Abstract

PURPOSE:To improve safety during turning in a control device provided with a high/low speed switching device which makes switching so that the peripheral speed of front wheels may be higher than that of rear wheels by detecting the connection of a pair of right and left brake pedals to make it impossible to switch the high/low speed switching device under a low speed condition. CONSTITUTION:A tractor transmits the power of an engine 2 to right and left rear wheels 11 through a main clutch 12, a main transmission 13, a sub transmission 13a and a rear wheel differential device 14, and transmits it to right and left front wheels 9 through a gear mechanism 16, a transmission shaft 18, a high/low speed switching device 19, a propeller shaft 20 and a front wheel differential device 21. The high/low speed switching device 19 provides a two-wheel driving condition during disengaging low and high speed hydraulic clutches 21, 22, a four-wheel driving condition during engaging the low speed hydraulic clutch 21, and a double speed turning condition in which front wheels 9 are rotated approximately twice as high as the peripheral speed of rear wheels 11 during engaging the high speed hydraulic clutch 22. In this case when a connection detector 38 detects the connection of a pair of right and left brake pedals, the high/low speed switching device 19 is controlled so as to make switching to low speed impossible.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a swing control device for a tractor.

(Prior art) In a four-wheel drive tractor that drives front and rear wheels, a high-low speed switching device is installed in the front wheel drive system, and the high-low speed switching device is installed when a turning detection device linked to the steering system detects a turning. There is a device that switches from low speed to high speed, increasing the circumferential speed of the front wheels to about twice the circumferential speed of the rear wheels from the normal running state where the front and rear wheels are synchronized, making it possible to make sharp turns in a small radius.

This kind of turning control is used exclusively when traveling at low speeds, such as when working in a field, and if used when traveling at high speeds, such as when traveling on a road, it is common to cause a fall accident.

Therefore, a release switch is provided in the control circuit, and when the vehicle is traveling at high speed, the release switch is operated to turn off the turning control.

(Problem B that the invention seeks to solve) However, in the past, a release switch was simply provided, and the operator had to turn it off manually when driving at high speeds, which caused the problem of falling accidents caused by forgetting to turn it off. .

In view of these conventional problems, the present invention disables the high/low speed switching device when the pair of left and right brake pedals are connected when driving on the road, and also prevents high speed driving even if the pair of left and right brake pedals is connected. The purpose of this system is to make the system inoperable so that the driver can safely turn in normal four-wheel drive.

(Means for Solving the Problems) The present invention includes a turning detector 28 that is linked to a steering system, and a turning detector 28 that causes the circumferential speed of the front wheels 9 to be higher than the circumferential speed of the rear wheels 11 when turning. In a tractor equipped with a high/low speed switching device 19 that switches between the left and right brake pedals 36, the pair of left and right brake pedals 36 that operate the left and right rear wheel brakes 37 can be freely disconnected from each other. a connection detector 38 for disabling the high/low speed switching device 19 in a low speed state, and a high speed detector 29 for detecting the traveling speed and disabling the high/low speed switching device 19 in a low speed state when traveling at high speed. It has been established that

(Function) When the pair of left and right brake pedals 36 are connected when traveling on the road, the connection detector 38 is activated and the high/low speed switching device 19 becomes unable to switch in a low speed state. Therefore, even if the turning detector 28 detects a turn, the tractor turns with normal four-wheel drive.

Even if you forget to connect the brake pedal 36, if you drive at high speed, the high speed detector 29 will work and the high/low speed switching device 1 will operate.
9 cannot be switched at low speeds, it is possible to turn safely without fear of falling over.

(Example) Hereinafter, the present invention will be described in detail with reference to the illustrated example.
In the figure, 1 is a tractor body, which includes an engine 2, a clutch housing 3, a transmission case 4, and the like. 5 is a bonnet, 6 is a handle, 7 is a driver's seat, and 8 is a hydraulic system for lifting and lowering the working machine.

A pair of left and right front wheels 9 are supported at both left and right ends of a front axle case 10 suspended at the front of the tractor body 1, and are capable of steering operation in conjunction with a steering system including a steering wheel 6 and the like. 11 is a pair of left and right rear wheels, 35 is a cabin,
36 is a pair of left and right brake pedals.

Figure 1 shows the traveling power transmission system and its control system. 12 is a main clutch, 13 is a main transmission, 13a is a sub-transmission,
14 is a rear wheel differential device, and power is transmitted from this rear wheel differential device 14 to the left and right rear wheels 11 via the left and right Hiiragi speed reduction devices 15. Note that each rear wheel 11 is controlled by a rear wheel brake 37. Reference numeral 16 denotes a gear mechanism for the front wheel drive system 17, which connects the left and right front wheels 9 via the gear mechanism 16, the transmission shaft 18, the high/low speed switching device 19, the propeller shaft 20, and the front differential device 21.
Power is transmitted to.

The high-low speed switching device 19 includes a low-speed transmission system that directly connects the transmission shaft 18 and the propeller shaft 20 with a transmission ratio of 1:1 via a low-speed hydraulic clutch 21, a high-speed hydraulic clutch 22, and a gear train 23.
, a high-speed transmission system that interlocks and connects the transmission shaft 18 and propeller shaft 20 via an intermediate shaft 24 and a gear train 25 at a transmission ratio of 1:2. Hydraulic clutch 21. 22 is a friction type, and when both hydraulic clutches 21 and 22 are disconnected, the front wheel 9 is in an idle state and the rear wheel 11 is used for two-wheel drive, and when the low-speed hydraulic clutch 21 is connected, the front wheel 9 is approximately synchronized with the rear wheel 11. The four-wheel drive system rotates at a circumferential speed, and when the high-speed hydraulic clutch 22 is engaged, the front wheels 9 rotate at about twice the circumferential speed of the rear wheels 11, resulting in double-speed turning.

26 is a solenoid valve that controls switching of the hydraulic clutches 21 and 22;
27 is a control circuit that drives this solenoid valve 26. 28
is a turning detector which is configured to turn on when the turning angle of the front wheels 9 reaches approximately 35° or 45° in conjunction with the operation of the steering system. Note that this rotation detector 28
Alternatively, the rotation of the handle 6 or the rotation of the front wheel 9 around the king pin may be directly detected, and as long as the rotation movement can be detected, the mounting position is not particularly limited. 29 is a high speed detector, and as shown in FIG.
By detecting the highest speed of the vehicle, high-speed driving can be detected in advance. That is, the main transmission 1j
I3 is a shift fork 33 fixed to a shift rod 32 by a main shift lever 31 supported by a transmission platform 30.
The high speed detector 29 detects the shift fork 33 and turns it on when the main shift lever 31 is operated to the highest gear. It is installed inside the mission case 13 so as to A connection detector 38 detects connection of the pair of left and right brake pedals 36, and is installed as shown in FIGS. 4 and 5.

That is, as shown in FIGS. 4 and 5, the pair of left and right brake pedals 36 are suspended from a support shaft 40 on the side of the instrument panel 39, and are urged in the return direction by a tension spring 41. A cylindrical body 43 is fixed to the pedal plate 42 of each brake pedal 36, and a connecting pin 4 is attached to the cylindrical body 43.
4 is inserted into the other cylindrical body 43 so as to be freely insertable and removable. Therefore, if the pair of left and right brake pedals 36 are connected by this connecting pin 44, the left and right rear wheel brakes 37 can be operated simultaneously by both pedals 36, and if the connection is released, the left and right rear wheel brakes 37 can be operated by the pair of left and right brake pedals 36. The rear wheel brake 37 can be operated independently. Note that the connecting pin 44 has a bent portion 45, and the bent portion 45
can be locked in the released position of one end of the guide groove 47 of the guide plate 46. Note that 48 is a tension spring. Connected detector 3
8 is attached to the pedal plate 42 on the opposite side to the connecting pin 44, and the pair of left and right brake pedals 36 are connected by the connecting pin 44.
When connected, it is operated by this and turns on.

The control circuit 27 connects the low-speed hydraulic clutch 21 when the turning detector 28 is off, and connects the low-speed hydraulic clutch 2 when the turning detector 28 is on.
1 is disengaged and the high-speed hydraulic clutch 22 is connected, and the rotation detector 28 is configured to operate when the coupling detector 38 is turned on and when the high-speed detector 29 is turned on. Low speed hydraulic clutch 2 even if turned on
1 remains connected, and is configured not to switch from the low-speed hydraulic clutch 2l to the high-speed hydraulic clutch 22. The control circuit 27 is provided with a release switch for preventing the solenoid valve 26 from operating when the rotation detector 28 is turned on.

When working in the field, the pair of left and right brake pedals 36 are disconnected by the connection bin 44, and the main transmission 13 is set to a gear other than the highest speed to drive at low speed, so the connection detector 38 and high speed detector 29 remains off,
Control circuit 27 operates as before. That is, when the steering wheel 6 is operated to make a sharp turn at the edge of the field and the front wheel 9 reaches a predetermined turning angle, the turning detector 28 is turned on, so that the control circuit 27
operates to switch the solenoid valve 26 from low speed to high speed. Therefore, the low speed hydraulic clutch 21 is disconnected and the high speed hydraulic clutch 2
2 is connected, the high/low speed switching device 19 switches from low speed to high speed, the front wheels 9 rotate at approximately twice the circumferential speed of the rear wheel 11, and the tractor can quickly turn in a small radius.

Next, when driving at high speeds on the road, such as when moving around a field, the pair of left and right brake pedals 36 are connected by the connecting pin 44.
Even when one of the brake pedals 36 is depressed, the left and right rear wheel brakes 37 always brake the rear wheels 11 at the same time. At this time, the connected detector 3 is
8 is turned on, and the control circuit 27 cuts off the signal from the rotation detector 28. Therefore, even when turning, the high/low speed switching device 19 remains in the low speed state, and the tractor turns safely with normal four-wheel drive in which the front and rear wheels 9,11 rotate at substantially synchronized circumferential speeds.

On the other hand, when driving on the road, the main transmission lever 31 is operated to put the main transmission I3 into the highest gear, but at this time the shift rod 32 and shift fork 33 move in the direction of the arrow a in FIG. , the high speed detector 29 is activated by the shift fork 33 and turned on, and the control circuit 27 turns on the rotation detector 2.
Block the signal from 8. Therefore, even if the brake pedal 36 is forgotten to be engaged, the vehicle can still turn with normal four-wheel drive.

In the case of FIG. 3, a limit switch or the like is used as the high-speed detector 29, but the present invention is not limited to this, and the following modifications are possible.

That is, a laser beam type is used as the high-speed detector 29,
As shown by the imaginary line in FIG. 2, the laser beam may be attached to the tractor body 1 so as to emit a laser beam toward the ground, and the actual traveling speed of the tractor may be detected.

Further, the high speed detector 29 is of a rotation speed detection type that detects the rotation speed using voltage or the like, and is configured to detect the rotation speed of one of the differential yoke shafts 49 of the rear wheel differential device 14, as shown in FIG. Also good. Of course, this can also be provided on the yoke shaft of the front wheel differential device 14.Furthermore, when using the rotation speed detection type high speed detector 29, as shown in FIG. , both detected values may be averaged and corrected by the averaging circuit 50. In this way, it is possible to correct when either the left or right rear wheel 11 slips, and reliability is improved.

As shown in FIG.
2 is made of an insulating material such as resin, and when a pair of left and right brake pedals 36 are connected with a connecting pin 44, both pedals 36
The space may be electrically conductive.

The coupled detector 38 and the high speed detector 29 can also be used in combination.

(Effects of the Invention) According to the present invention, the connection detector 38 detects the connection of the pair of left and right brake pedals 36 to disable the high/low speed switching device 19 in a low speed state, and the connection detector 38 detects the traveling speed. A high-speed detector 29 is provided to disable the high-low speed switching device 19 at low speeds when driving at high speeds, so when driving on the road, by connecting the pair of left and right brake pedals 36, it is possible to turn using normal four-wheel drive. Even if you forget to connect it, you can always turn with normal four-wheel drive when driving at high speeds, significantly improving safety when turning.

[Brief explanation of drawings]

Fig. 1 is a configuration diagram of the main parts showing one embodiment of the present invention, Fig. 2 is a side view of the tractor, Fig. 3 is a sectional view of the high speed detection section, and Fig. 4 is a side view of the brake pedal section. 5 is an enlarged view taken along the line V-V in FIG. 4, FIGS. 6 and 7 are configuration diagrams showing other embodiments of the present invention, and FIG. 8 is an exploded perspective view of the same brake pedal. be. ■--Tractor body, 9.1 front wheel, 11.1 rear wheel, 1
3-・Main transmission device, 19-high/low speed switching device, 27-control circuit, 28-1 turning detector, 29--1 high speed detector, 3
6-brake pedal, 37--rear wheel brake, 38 series connection detector.

Claims (1)

[Claims] (1) A turning detector (28) that is linked to the steering system, and a front wheel (9) that is linked to the turning detector (28) when turning.
a pair of left and right brake pedals (3) that operate the left and right rear wheel brakes (37);
6), a coupling detector (38) for detecting coupling of the pair of left and right brake pedals (36) and disabling the high/low speed switching device (19) in a low speed state; A swing control device for a tractor, comprising: a high speed detector (29) for detecting the traveling speed and disabling the high/low speed switching device (19) in a low speed state when traveling at high speed.