JP2002172946A - Tractor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To smoothly turn a body at a desired turning radius. SOLUTION: This tractor has a differential front wheel speed-up mechanism 21 for transmitting a driving force from an engine 2 to front and rear wheels 4 and 7. The differential front wheel speed-up mechanism 21 is interlocked and connected to a steering member 5, and the front wheel speed-up mechanism 21 is operated interlocking with an operation of the steering member 5 to increase or decrease speeds of the front and rear wheels 4 and 7.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a tractor which is equipped with an agricultural work machine such as a tilling work machine at a rear portion of a machine body to perform various agricultural works.

[0002]

Conventionally, a central differential mechanism is provided at the center of a drive system connecting the front wheels and the rear wheels, and the speed ratio of the front and rear wheels is changed by the central differential mechanism during the turning of the body to make the body smooth. There is a front wheel speed increasing means for turning. However, in the case of such means, there are problems such as slippage occurring depending on the state of the load applied to the front and rear wheels, and inability to perform stable turning because the speed ratio between the front and rear wheels is not stable.

[0003]

SUMMARY OF THE INVENTION Accordingly, the present invention provides a differential front wheel speed increasing mechanism for transmitting driving force from an engine to front and rear wheels.
When the front wheel speed-up mechanism is operated in conjunction with the operation of the steering member to accelerate and decelerate the front and rear wheels, and when the aircraft is turned by operating the steering member such as the steering wheel, the front wheel speed-up mechanism also operates, In addition to turning the front and rear wheels at a speed ratio suitable for the turning radius, the turning of the airframe is performed satisfactorily, and a shock accompanying a speed change is eliminated to improve turning performance.

Further, a front wheel speed increasing mechanism is constituted by two front and rear planetary gear mechanisms, and an actuator driven in accordance with a steering wheel turning angle is connected to the front and rear planetary gear mechanisms in forward and reverse directions.
When the steering wheel is turned, an output difference is generated in the front and rear planetary gear mechanism to make the front and rear wheel speed ratios different.When turning the aircraft, the front and rear wheel speed ratio according to the turning radius is selected, and the target It is intended to smoothly turn the aircraft with a turning radius.

[0005] Further, as the turning angle of the steering wheel becomes larger, the front wheel side is accelerated and the rear wheel side is decelerated to enable a good turning while keeping the average speed of the body substantially constant. This improves workability.

[0006]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a side view of the whole, and FIG. 2 is a plan view of the same. In FIG. 1, (1) is a tractor, and an engine (2) is shown.
(3) Left and right front wheels (4) on both sides
(4), a round steering handle (5) is provided at the rear of the hood (3), and a driver's seat (6) is installed behind the handle (5). The left and right rear wheels (7) and (7) are installed on the vehicle, and the left and right brake pedals (9) and (9) and the clutch pedal (10) are arranged on the front step (8) of the driver's seat (6). Is seated on the driver's seat (6) and travels, and at the rear of the tractor
Rotary cultivator (1) via the point link mechanism (11)
2) is installed so as to be able to move up and down freely to perform tilling work.

A traveling main transmission lever (13) and an elevating lever (14) for elevating and lowering the work implement (12) are disposed on the right side of the driver's seat (6).
5) and a PTO shift lever (16) for shifting the output of the work implement (12) is disposed on the left side of the driver's seat (6).

As shown in FIG. 3, a power transmission mechanism (17) for the engine (2) includes a main clutch section (18) for disconnecting engine power, and a main and sub-motor for changing a power rotational speed according to a working state. A transmission case (20) having a transmission unit (19), and a central forced differential for distributing the output from the auxiliary transmission unit of the transmission case (20) to the front wheels (4) and the rear wheels (7) so that the speed ratio can be changed. A mechanism (21) and a front-rear speed change output from the forced differential mechanism (21) are input to cause a differential phenomenon in the rotation of each of the left and right front wheels (4) (4) and the rear wheels (7) (7). Front and rear differential mechanism (22) (2
3), and the output of the engine (2) is transmitted to the main / sub transmission unit (1).
9) and transmitted to the front wheel (4) and the rear wheel (7) via the central forced differential mechanism (21) and the front-rear differential mechanism (22) (23) to travel and turn the body. .

As shown in FIGS. 4 to 7, the central forced differential mechanism (21) includes a pair of front and rear symmetric planetary gear mechanisms (24) and (25) for front and rear wheels. (2
4) (25) is a single sun gear (26) and a plurality of planetary gears (2) meshing on the outer periphery of the sun gear (26).
7) and a ring gear (28) meshing with these planetary gears (27) and the like. A large-diameter center gear (30) is fixed to the center of a sun gear shaft (29) connected to the front and rear sun gears (26). The small-diameter output gear (32) fixed to the output shaft (31) of the case (20) meshes with the center gear (30) to rotate the sun gear (26).

The planetary gear (27) is rotatably supported by carriers (35) of carrier shafts (33) and (34), which are front and rear output shafts on the same axis as the sun gear shaft (29). (28) has internal teeth (28a) meshing with each planetary gear (27), and is disposed on the same axis as the sun gear shaft (29), and is arranged in front and rear, and the sun gear shaft (29) or the carrier shaft (33). (3
4) rotatably supported.

Furthermore, a variable displacement hydraulic motor (36)
A speed-increasing gear (38) is attached to the rotating shaft (37), and a speed-change input gear (40) fixed to the speed-change shaft (39) meshes with the speed-increasing gear (38), and both ends of the speed-change shaft (39) Gears (41) and (42) are fixed to the external gear (28A), which is a front ring gear, and the external gear (28b) is connected to the speed increasing gear (41) via a reverse rotation gear (43). , External teeth (28) of a rear gear (28B) which is a rear ring gear.
b), the reduction gear (42) is directly connected to the front and rear gears (28A) (2) when the hydraulic motor (36) is driven forward.
8B), the front gear (28A) is rotated reversely and the rear gear (28B) is rotated forward at the same rotational speed.

The differential mechanisms (22) and (23) include a drive pinion gear (44) and a drive side gear (45).
And a differential pinion gear (47) and a side gear (48) provided in a differential case (46) of the side gear (45).
A front pinion gear (44) is connected to a front carrier shaft (33) via a propulsion shaft (49), a rear pinion gear (44) is connected to a rear carrier shaft (34), and a differential side gear (48) is connected. By connecting the front and rear wheels (4) and (7) to the rotating shaft (50), the left and right front and rear wheels (4) (4).
(7) The differential phenomenon is caused in (7).

Further, a steering gear (52) provided at a lower end of the handle shaft (51) of the steering handle (5) is connected to the steering shaft (5).
3) meshing with the sector gear (54), rotating the steering shaft (53) according to the steering wheel turning angle (handle angle) operated by the steering handle (5), and turning the front wheel (4) in the direction. A steering arm (56) integral with the sector gear (54) is linked to the steering mechanism (55) for conversion. In addition, one end of a connecting member (58) such as a link and a wire is connected to a control arm (57) for driving and changing the rotation speed of the hydraulic motor (36). The steering shaft (53) is equipped with a forward / reverse switching mechanism (59) for switching to reverse rotation, and the output arm (60) of the switching mechanism (59) is connected to the connecting member (5).
The other end of the rear wheel (8) is connected so that the front wheel (4) is reversely accelerated and the rear wheel (7) is reversely decelerated during the reverse turning of the fuselage.

The actuator for rotating the speed increasing gear (38) may be any one of a hydraulic continuously variable transmission (HST), an electric motor and the like, in addition to the hydraulic motor (36). Further, an actuator such as a hydraulic motor (36) and the steering handle (5) may be connected by an electric means to electrically drive and control the actuator.

This embodiment is constructed as described above. As shown in FIG. 6, when the steering handle (5) is steered forward in the neutral position, the hydraulic motor (36) is set to the stop state, and the front and rear ring gears are set. Both (28A) and (28B) stop the rotation. For example, when the sun gear shaft (29) rotates clockwise in the traveling direction, the front and rear carrier shafts (33) and (34)
Is also rotated clockwise at the same rotational speed, so that the aircraft advances straight ahead. In addition, even when turning at a very low speed, the hydraulic motor (36) is kept in a stopped state, and the front and rear wheels (4) and (7) are turned at substantially the same speed as during forward movement.

As shown in FIG. 7, when the steering handle (5) is rotated left and right during the straight running, the hydraulic motor (36) is rotated by an amount corresponding to the turning angle of the handle (5). When the transmission shaft (39) rotates clockwise with the number of rotations (forward rotation), the front gear (28A) rotates clockwise and the rear gear (2) rotates.
8B) is rotated to the left, and the front carrier shaft (33) increases the rotation and the rear carrier shaft (34) is decelerated to increase the turning radius (the steering wheel turning angle) by the amount corresponding to the turning angle of the steering wheel.
The front wheel (4) is rotated forward and accelerated and the rear wheel (7) is rotated forward and decelerated to a speed suitable for driving, and the turning performance is improved by performing smooth turning of the aircraft with reduced tire wear on the front wheel (4). It is to let.

Also, when the speed ratio of the front and rear wheels (4) and (7) changes from an appropriate value due to replacement of the rear wheel (7) with a half crawler or a change in tire size, the hydraulic motor (36) is driven. Thus, the speed ratio of the front and rear wheels (4) and (7) can be easily maintained at an appropriate value.

As shown in FIG. 8, the sun gear shaft (29) and the front and rear carrier shafts (3) during reverse running reverse to the forward running described above.
3) When the (34) rotates to the left, the hydraulic motor (36) is reversed in response to the turning operation of the steering handle (5), and when the vehicle is turning backward, the front wheel (4) is reversely accelerated, and the rear wheel ( 7)
In the reverse deceleration state, and the main speed change lever (13)
In response to switching between forward and reverse, the rotation of the hydraulic motor (36) operated by the steering handle (5) is also switched between forward and reverse by the forward / reverse switching mechanism (59) to operate the steering handle (5). The sensation is the same as when moving forward (turning right when steering the steering wheel (5) to the right) to perform reverse turning.
In this case, the number of rotations of the hydraulic motor (36) at the time of reversing is suppressed slightly lower than at the time of moving forward, and the turning operation is stabilized.

FIG. 9 is a diagram showing the above relationship, in which the front and rear wheels (4) and (7) are rotated at the same speed when the body is running straight, and the steering wheel is turned when the body is turned forward and backward. The front wheel (4) is accelerated and the rear wheel (7) is decelerated in a proportional relationship in accordance with the turning angle, so that the average speed of the body is maintained substantially constant.

The gear shown in FIG. 10 has a front gear (28A) through a large-diameter speed increasing gear (61) and a rear gear (28B) through a small-diameter reverse gear (62) and a reduction gear (63). The shaft (39) is interlocked and provided so that the drive of the hydraulic motor (36) is reversed while the drive of the hydraulic motor (36) is made forward in the forward turning of the previous embodiment, and the ring gear (28) is driven by the hydraulic motor (36). The reduction ratio is increased, and the deceleration of the rear wheel (7) is suppressed to be smaller than that in the forward turning of the previous embodiment, thereby improving the efficiency of the turning work when the turning radius is large.

As described above, the center forced differential mechanism (21), which is a differential front wheel speed increasing mechanism for transmitting the driving force from the engine (2) to the front and rear wheels (4) and (7), is provided. The differential mechanism (21) is operated in conjunction with the operation of a certain steering handle (5) to accelerate and decelerate the front and rear wheels (4) and (7).
When the body is turned by operating the steering handle (5), the differential mechanism (21) is simultaneously operated, and the front and rear wheels (4) and (7) are rotated at a speed ratio suitable for the turning radius, so that the body can be turned well. Turning can be performed, and a shock accompanying a speed change can be eliminated to improve turning performance.

Further, the two front and rear planetary gear mechanisms (24)
(25) constitutes the differential mechanism (21), and is a hydraulic motor (3) which is an actuator that is driven according to the steering angle.
6) is interlockingly connected to the front and rear planetary gear mechanisms (24) and (25) in the forward and reverse directions to cause an output difference between the front and rear planetary gear mechanisms (24) and (25) when the steering handle (5) is turned. ,
The front and rear wheels (4) and (7) have different speed ratios, and appropriate front and rear wheels (4) and (7) according to the turning radius when the aircraft turns.
Is selected, and the aircraft turns smoothly at the target turning radius.

Further, as the steering angle of the steering wheel (5) becomes larger, the front wheel (4) side is accelerated and the rear wheel (7) side is decelerated, so that the average speed of the body is kept substantially constant. It is possible to improve the workability by enabling the turning with good small turning performance.

Further, in the case of a differential transmission configuration in which the front wheel (4) side is accelerated and the rear wheel (7) side is decelerated during such a turn,
Since turning at high speeds is also restricted, it is not necessary to check at high speeds, and even if the vehicle shifts to turning even at high speeds, the speed is automatically controlled to a low speed to improve work stability.

[0025]

As is apparent from the above embodiments, the present invention provides the driving force from the engine (2) by using the front and rear wheels (4) and (7).
The front wheel speed increasing mechanism (21) is linked to the steering member (5), and the front wheel speed increasing mechanism is interlocked with the operation of the steering member (5). Since the front and rear wheels (4) and (7) are accelerated and decelerated by operating the mechanism (21), the front wheel speed increasing mechanism (21) is used when turning the aircraft by operating the steering member (5) such as a steering handle. Also operate simultaneously to rotate the front and rear wheels (4) and (7) at a speed ratio suitable for the turning radius, to perform a good turning of the aircraft, and to eliminate the shock accompanying the speed change to improve turning performance. Can be done.

Further, the two front and rear planetary gear mechanisms (24)
(25) constitutes a front wheel speed increasing mechanism (21), and an actuator (36) driven in accordance with the steering wheel turning angle is connected to the front and rear planetary gear mechanisms (24) and (25) in forward and reverse directions,
When the steering handle (5) is turned, an output difference is generated between the front and rear planetary gear mechanisms (24) and (25), and the front and rear wheels (4)
Since the speed ratio of (7) is made different, an appropriate speed ratio of the front and rear wheels (4) and (7) according to the turning radius is selected at the time of turning the aircraft, and the aircraft is smoothly turned at the target turning radius. It can be turned.

Further, as the steering angle of the steering wheel (5) becomes larger, the front wheel (4) side is accelerated and the rear wheel (7) side is decelerated, so that the average speed of the body is substantially constant. It is possible to improve the workability by making it possible to make a turn with good small turning performance and maintain good turning.

[Brief description of the drawings]

FIG. 1 is an overall side view.

FIG. 2 is an overall plan view.

FIG. 3 is an explanatory diagram of a traveling drive system of a tractor.

FIG. 4 is an explanatory diagram of a differential mechanism.

FIG. 5 is an explanatory view of connection between a central forced differential mechanism and a steering handle.

FIG. 6 is an explanatory diagram showing a forward and straight traveling state of the drive system.

FIG. 7 is an explanatory diagram showing a forward turning state of the drive system.

FIG. 8 is an explanatory view showing a backward turning state of the drive system.

FIG. 9 is a diagram showing the relationship between turning and speed.

FIG. 10 is an explanatory diagram showing an acceleration / deceleration state of the drive system.

[Explanation of symbols]

 (2) Engine (4) Front wheel (5) Steering handle (steering member) (7) Rear wheel (21) Forced differential mechanism (front wheel speed-up mechanism) (24) (25) Planetary gear mechanism (36) Oil pressure Motor (actuator)

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2B043 AA03 AB08 BA02 BB01 BB03 DA04 DB04 3D043 AA03 AB12 AB17 EA02 EA24 EA42 EB14 EE07 EE08 EE12 EF16 EF18

Claims (3)

[Claims] 1. A front wheel speed increasing mechanism for transmitting a driving force from an engine to front and rear wheels, wherein the front wheel speed increasing mechanism is interlocked to a steering member, and the front wheel speed increasing mechanism is interlocked with the operation of the steering member. A tractor, wherein the tractor is provided so as to increase and decrease the speed of front and rear wheels by operating a speed mechanism. 2. A front wheel speed increasing mechanism comprising two front and rear planetary gear mechanisms, and an actuator driven in accordance with a steering angle of the steering wheel is connected to the front and rear planetary gear mechanisms in forward and reverse directions so that the steering wheel can be turned at the time of turning operation. The tractor according to claim 1, wherein an output difference is generated between the front and rear planetary gear mechanisms so as to make the speed ratio between the front and rear wheels different. 3. The tractor according to claim 1, wherein the steering wheel is provided so as to increase the speed of the front wheels and to reduce the speed of the rear wheels as the steering angle of the steering wheel increases.