JP2622107B2 - Front wheel drive control device for four-wheel drive agricultural tractor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a front-wheel drive control device for a four-wheel drive agricultural tractor.

[0002]

2. Description of the Related Art Conventionally, a technique for increasing the peripheral speed of a front wheel when a four-wheel drive agricultural tractor makes a turn at the field end is known, for example, as disclosed in Japanese Patent Application Laid-Open No. Sho 54-12138.

[0003]

However, in the conventional front wheel drive control device, when the steering wheel is operated at a turning angle of, for example, 40 degrees or more, the speed of the front wheels is automatically switched with respect to that of the rear wheels. The switching operation to increase the speed is performed regardless of the traveling speed, whether the traveling speed is low or high.

[0004] Therefore, when the work such as tilling or scraping is performed in a field, the speed is always low, so that there is no problem even if the front wheels are driven at an increased speed. You do it. However, when driving on the road (during high-speed driving), when the steering wheel reaches a sharp curve and the steering wheel is operated by a predetermined angle or more, if the front wheels are switched to speed-up, the front wheels suddenly start a sharp turn, and steering stability is impaired. ,Also,
There is a problem that not only an overload occurs in the transmission, the differential, the drive shaft, and the like, but also that the tires are worn out early.

In an agricultural tractor, the front wheels are
Because it is a steered wheel and is not covered with a fender to ensure forward visibility, a considerable amount of mud may jump up when the front wheels are driven at an increased speed during high-speed running. That is, when a small turn is performed by increasing the front wheel speed in a wet field or the like in a high-speed running state, a large amount of mud is flipped backward and left and right by the front wheel. Case), the mud was spread, and the mud was scattered outside from the headland, thereby contaminating the alleys around the field.

Therefore, in the present invention, it is determined that it is necessary to reduce the turning radius when the traveling speed is low while working in a field or the like, and only at that time the front wheels automatically increase with respect to the rear wheels. Speed, prevent the front wheels from switching to increased speed at high speeds, reduce mud bouncing when turning in wet fields, and reduce power loss during small turning. The purpose is to do so.

[0007]

According to the present invention, the left and right front wheels 5, 5 which can be steered by the steering handle 8 and can be driven by the front wheel traveling transmission system 25, and the traveling speed can be shifted in a plurality of high and low steps. The object described above is achieved in a four-wheel drive agricultural tractor having left and right rear wheels 6, 6 driven by a rear wheel traveling transmission system M having a simple traveling transmission device 16 and a rear wheel differential device 17. In order to do so, the following technical measures have been taken.

That is, according to the present invention, the front wheel traveling power transmission system 25 is branched from a rear wheel traveling power transmission system M between the traveling transmission 16 and the rear wheel differential device 17, and the front wheel traveling power transmission system 25 is provided. Drive rotation to the front wheels 5 and 5 is performed on the rear wheels 6 and 25.
6, a front wheel speed changeover device 30 that can be switched to a speed increase or substantially the same speed, a front wheel differential device 32 driven via the front wheel speed changeover device 30, and a drive rotation of the front wheels 5, 5 is cut off. The front wheel speed change-over switching device 30 switches from the substantially same speed to the speed increase only when the steering angle of the left and right front wheels 5, 5 is equal to or larger than the set angle and the traveling speed is low. It is characterized by the fact that it is configured to make a turning run, and by adopting such a configuration, it is approaching a sharp curve when traveling on the road etc. in a high speed running state for movement. As a result, it is possible to prevent the front wheels 5 from being accelerated when the steering wheel 8 is turned, and to ensure the steering stability without the front wheels 5 undergoing a sharp turning operation due to the speed increase switching during high-speed steering. be able to.

Further, when turning and steering in a wet field or the like,
Since the front wheel speed changeover device 30 is configured to switch from substantially the same speed to the speed increase only when the traveling speed is low, the small turning by the speed increase of the front wheels 5 is not performed at the time of high speed traveling, and the mud by the front wheels is not generated. Can be suppressed to an allowable range. Further, since the front wheels 5 are driven at an increased speed only when the traveling speed is low, power loss during turning steering can be suppressed to a small extent and tire wear can be prevented.

Further, the front wheel drive transmission system 25 is provided with a clutch means 28 for connecting and disconnecting the drive rotation of the front wheel 5, so that four-wheel drive with high-speed restraint according to the work situation,
It can be switched to rear wheel drive.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to the illustrated embodiment. FIG. 1 illustrates a four-wheel drive agricultural tractor, in which 1 is a tractor body, an engine 2, and an engine 2.
It is composed of a clutch housing 3, a transmission case 4, etc., and has left and right front wheels 5 and left and right rear wheels 6 that can be driven and rotated. Reference numeral 7 denotes a hood, and 8 denotes a steering handle. As shown in FIG. 3, the left and right front wheels 5 can be steered from a steering gear box 9 on the tractor body 1 via a sector shaft 10, a pitman arm 11, a drag ring 12, and the like. .
Reference numeral 13 denotes a driver's seat, and reference numeral 14 denotes a hydraulic device for lifting and lowering the work implement.

As shown in FIG. 2, a transmission transmission system M such as a traveling transmission 16 and a rear wheel differential 17 interlocked with the engine 2 via a clutch 15 is built in the transmission case 4, and the rear wheels The differential device 17 is linked to each rear wheel 6 via a final reduction gear 18. Each rear wheel 6 has a rear wheel brake 19
The rear wheel brakes 19 can be operated simultaneously or independently of each other by interlocking and independent operation of a pair of left and right brake pedals 20 juxtaposed on one side of the tractor body 1. ing.

The traveling transmission 16 has a main transmission section 21 and an auxiliary transmission section 22. The main transmission section 21 can change the traveling speed in multiple steps by a main transmission lever (not shown). The speed can be shifted between high and low speeds H and L by the sub-transmission lever 23. The sub-transmission portion 22 is provided with a low-speed detector 24 such as a limit switch for detecting a low speed side of the sub-transmission lever 23, that is, a low vehicle speed.

A transmission shaft 26, 27 of a front wheel transmission transmission system 25 interlocked therewith is mounted under the traveling transmission 16 in parallel with each other, and a manually operable clutch means 28 is provided between the transmission shafts 26, 27. Is provided. Here, the front wheel traveling transmission system 25 is provided to be branched from the rear wheel traveling transmission system between the traveling transmission 16 and the rear wheel differential device 17. That is, the gear is branched by step-contacting the shift gear 17B provided on the drive pinion shaft 17A of the rear wheel differential device 17 with the gear 26A provided on the transmission shaft 26.

Further, the transmission shaft 27 has a gear 27A, and the power take-out case 2 mounted on the lower abdomen of the transmission case 4.
9 interlocks with a front wheel differential device 32 in a front axle case via a propulsion shaft 31 from a front wheel speed changeover device 30 in the front wheel axle 9, and interlocks with each front wheel 5 from the front wheel differential device 32 via a final reduction device 33. Can be increased or substantially equalized with respect to the rear wheel 6.

A front wheel speed changeover device 30 capable of changing the speed of the front wheels 5 to substantially the same speed as the front wheel 5 includes a planetary speed reducer 34 engaged with a gear 27A, a same speed hydraulic clutch 35 and a speed increasing hydraulic clutch 36. When the same-speed hydraulic clutch 35 is connected, the peripheral speed of the front wheel 5 is about 1.05 times that of the rear wheel 6, and when the speed-increasing hydraulic clutch 36 is connected, the peripheral speed of the front wheel 5 is about twice that at low speed. The two clutches 35, 3
The front wheel 5 can be connected and disconnected by cutting both the wheels 6.

That is, when the speed-increasing hydraulic clutch 36 is connected in conjunction with the turning operation of the steering handle 8, the front wheels 5 are driven to increase speed, and when the clutch 36 is disengaged and the clutch 35 is engaged, the front wheels 5 are substantially disengaged. It is assumed that they are driven at the same speed. FIG. 3 shows a control system, in which 37 is a hydraulic pump, 38 is a flow dividing valve, and 39 is a relief valve. Reference numeral 40 denotes a three-position switching electromagnetic valve which constitutes switching means for the same-speed hydraulic clutch 35 and the speed-increasing hydraulic clutch 36. The solenoid valve 40 has solenoids 41 and 42 and is controlled by a control circuit 43.

Reference numeral 44 denotes a turning detector, which detects when the steering angle of the steering wheel 8 exceeds a certain value in conjunction with the sector shaft 10. 45 is a one-brake detector, which releases the interlock of the left and right brake pedals 20 and operates it.
It is configured to detect as one-sided operation of the rear wheel brake 19. 46 is a switch. A high-speed detector 47 detects a high speed of the vehicle speed. The high-speed detector 47 may detect the high speed of the sub-transmission unit 22 or may detect the high-speed side of the multi-speed transmission of the main transmission unit 21.

In this embodiment, the control circuit 43 comprises a low speed detector 24, a turning detector 44 and a one-brake detector 4.
5 is given to the solenoid 42 of the solenoid valve 40 at the time of all the detections, and the same speed command is given to the solenoid 41 when any of them is missing. At the time, a disconnection command is given to the solenoids 41 and 42.

That is, in conjunction with the turning operation of the steering wheel 8, only when the running speed is low, the speed is switched from substantially the same speed to the increased speed, and the front wheel 5 is driven at an increased speed via the hydraulic clutch 36 to perform the turning. When the speed is high, the vehicle is turned without driving the front wheels 5, or the front wheels 5 are driven at the same speed. Next, the operation of the above embodiment will be described. When a rotary device is mounted behind the tractor body 1 to perform tilling work in a field, for example, the sub-transmission unit 22 is driven at a low speed to run at low speed. At this time, the high-speed detector 47 does not operate, and the low-speed detector 24 operates to operate the drain 41 of the solenoid valve 40.
Are excited, the same-speed hydraulic clutch 35 is connected, and the front wheel 5 rotates at a peripheral speed of about 1.05 times that of the rear wheel 6.

When turning at the end of the field, the steering wheel 8 is largely operated in the turning direction, and the brake pedal 20 in the turning direction, for example, in the case of turning in FIG. , Left rear wheel brake 19
As a result, the left rear wheel 6 is braked, and the vehicle turns one point using the brake as a fulcrum. At this time, in the present embodiment, the turning detector 44 and the one-brake detector 45 work, and the low-speed detector 24 has already been operated.
Is activated, the speed increase command is output from the control circuit 43, the solenoid 42 is excited, and the solenoid valve 40 is switched.
The speed increasing hydraulic clutch 36 is connected. Accordingly, the front wheel 5 is driven at a peripheral speed approximately twice as high as that at the same speed, so that the front wheel 5 does not become a resistance to the rear wheel 6 and the left rear wheel 6 is used as a fulcrum. Can turn quickly with a small radius.
After turning, if the steering wheel 8 is returned to its original state or the depression of the brake pedal 20 is released, the same-speed hydraulic clutch 35 is connected again. That is, only when the steering angle of the steering wheel 8 is equal to or greater than a certain value and the traveling speed is low, the front wheels 5 can be switched from substantially the same speed to the rear wheels 6 to drive at increased speed so that the vehicle can turn.

That is, only when the traveling speed is low, the front wheels 5
Is driven at an increased speed, so that the power loss during turning steering can be reduced as described below,
Tire wear can be prevented. In order to understand such a specific effect, the relationship between the peripheral velocities of the front wheels and the rear wheels at the time of the small turning is described with reference to FIG.

As shown in FIG. 5, small turning (rapid turning)
To do so, the turning center of the aircraft must be located near the side of the rear wheel. At this time, since the distance from the turning center of the front wheel average peripheral speed vector is larger than the distance from the turning center of the rear wheel average peripheral speed vector, it is necessary to set the front wheel average peripheral speed larger than the rear wheel average peripheral speed. Nature occurs.

FIG. 6 shows the relationship between the peripheral velocities. Ideally, as shown in FIG. 6 as an ideal ratio, the average peripheral velocity of the front wheels is gradually increased as the steering angle increases. However, due to structural limitations of the device, a two-stage switching type is provided in which the steering is switched from substantially the same speed to an increased speed when the steering is steered beyond a set angle.

In the example shown in FIG.
Although the front wheel average peripheral speed is set to be approximately twice as large as the rear wheel average peripheral speed when the vehicle is steered by more than °, the ideal ratio and the actual ratio greatly differ around the set angle, If the front-wheel speed-change switching device is speed-changed in a high-speed running state, an extremely large power loss occurs, and a great load is generated on the contact surfaces of the front wheels and the rear wheels, so that the tires are extremely worn.

In addition, if the front wheels are driven at an increased speed when the steering is steered at a set angle or more in a sharp curve or the like during high-speed running on the road, a transmission, a differential, a drive shaft, etc., constituting a drive mechanism are provided. In some cases, overloading occurs, or the tire turns prematurely due to such small turning at a high speed, and the tire needs to be replaced. Since the present invention is configured to drive the front wheels only at low speeds,
Even if the actual ratio between the front wheel average peripheral speed and the rear wheel average peripheral speed deviates from the ideal ratio, power loss and tire wear caused by driving the front wheel at increased speed during small turning can be kept within the allowable range. is there.

Also, when turning and steering in a wet field or the like,
The front wheel speed changeover device 30 is configured to switch from substantially the same speed to the speed increase only when the traveling speed is low. Can be suppressed to an allowable range. That is, when a small turn is performed by increasing the front wheel speed in a wet field or the like in a high-speed running state, a large amount of mud is flipped backward and left and right by the front wheel. In this case, mud is applied, and mud is scattered outside from the headland to soil alleys and the like around the field. However, according to the present invention, these can be prevented.

In the plowing operation in the field, for example, the sub transmission unit 22 is driven at a high speed to travel at a higher speed than during the rotary operation, but when turning, it is necessary to make a sharp turn with a small radius as described above. Therefore, at this time, since the low-speed detector 24 does not work, the switch 46 may be operated to provide a signal for low-speed detection to the control circuit 43. When the vehicle is traveling on the road, the vehicle travels at a high speed with a light load.
By disengaging both the speed increasing hydraulic clutch 36 and the rear wheel 6 alone, high-speed running can be achieved by sole driving of the rear wheel 6 alone, so that the tires of the front wheels 5 can be prevented from being worn, and unnecessary fuel consumption of the engine 2 can be prevented. During this high-speed running, the vehicle is turned so as to approach a sharp curve without driving the front wheels 5 whose steering angle of the steering wheel 8 is equal to or more than a certain value.

The detectors 24, 44, 4 of the embodiment
5, 47 may be any of a contact type and a non-contact type.

[0030]

As described above in detail, according to the present invention, it is possible to secure a small turning movement in the field, to select four-wheel drive or rear-wheel drive while checking at high speed according to the work situation. Sometimes, it is possible to prevent the front wheels from being switched to a speed increase, to reduce splashing of mud during turning steering in a field, and to further reduce power loss during small turning.

[Brief description of the drawings]

FIG. 1 is a side view of a tractor.

FIG. 2 is a configuration diagram of a traveling power system.

FIG. 3 is a block diagram of a control system.

FIG. 4 is a plan view of the tractor showing a turning operation.

FIG. 5 is a diagram showing a relationship between peripheral speeds of a front wheel and a rear wheel at the time of a small turn.

FIG. 6 is a diagram showing a steering angle and an ideal ratio and an actual ratio.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Tractor vehicle body 5 Front wheel 6 Rear wheel 8 Steering handle 16 Transmission 17 Rear wheel differential device 28 Clutch means 30 Front wheel speed increasing switching device 32 Front wheel differential device

Claims (3)

(57) [Claims] 1. Left and right front wheels (5) (5) that can be steered by a steering handle (8) and can be driven by a front wheel traveling transmission system (25), and that can change the traveling speed in a plurality of high and low steps. Four-wheel drive agricultural machine having left and right rear wheels (6) (6) driven by a rear wheel transmission system (M) including a traveling transmission (16) and a rear wheel differential (17). In the tractor, the front wheel drive train (25) is connected to the travel transmission (1).
6) and a rear-wheel drive transmission system (M) between the rear wheel differential device (17) and the front-wheel drive transmission system (2).
In 5), the drive rotation to the front wheels (5) and (5) is performed by the rear wheels (6).
(6) a front wheel speed changeover device (30) capable of switching to a speed increase or substantially the same speed, a front wheel differential device (32) driven via the front wheel speed changeover device (30), and a front wheel (5)
(5) clutch means (28) for connecting and disconnecting the drive rotation;
The front wheel speed changeover device (30) switches from the substantially same speed to the speed increase only when the steering angle of the left and right front wheels (5) and (5) is equal to or larger than the set angle and the traveling speed is low. A front-wheel drive control device for a four-wheel drive agricultural tractor, characterized in that the vehicle is configured to turn. The clutch means (28) for connecting and disconnecting the drive rotation of the front wheels (5) is provided with the front wheel speed increasing switching device (3).
2. The front-wheel drive control device for a four-wheel drive agricultural tractor according to claim 1, wherein the front-wheel drive control device is provided upstream of (0). 3. Left and right front wheels (5) (5) which can be steered by a steering handle (8) and can be driven by a front wheel drive transmission system (25); Four-wheel drive agricultural machine having left and right rear wheels (6) (6) driven by a rear wheel transmission system (M) including a traveling transmission (16) and a rear wheel differential (17). In the tractor, the front wheel drive train (25) is connected to the travel transmission (1).
6) and a rear-wheel drive transmission system (M) between the rear wheel differential device (17) and the front-wheel drive transmission system (2).
In 5), the drive rotation to the front wheels (5) and (5) is performed by the rear wheels (6).
(6) a front wheel speed changeover device (30) capable of switching to a speed increase or substantially the same speed, and a front wheel differential device (32) driven via the front wheel speed changeover device (30); The front wheel speed-increasing switching device (30) is provided for the left and right front wheels (5) (5).
Only when the steering angle is equal to or greater than the set angle and the traveling speed is low, the vehicle is turned from the substantially same speed to the increased speed and the vehicle is turned. Further, the front wheel speed increasing switching device (30) is provided with a speed increasing device. A hydraulic clutch (36) and a hydraulic clutch (35) for the same speed are provided, and the drive rotation of the front wheels (5) and (5) is connected and disconnected by turning on and off the hydraulic clutches (35) and (36). A front wheel drive control device for a four-wheel drive agricultural tractor, characterized in that: