JP3318973B2 - Tractor steering wheel drive - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a tractor steering wheel drive device.

[0002]

2. Description of the Related Art A clutch is provided between a steering wheel on one of the left and right sides of a tractor and a differential device for turning transmission on and off. In the form of two-wheel drive by disengaging the clutch, by applying a brake to the axle on the differential device side by this clutch disengagement,
High-speed (double speed) the steered wheels on the opposite side of this clutch release
In the form of the steered wheel drive device that is driven to facilitate the steerable turning, if the operation range of the brake is narrow, it is difficult to perform the steering smoothly.

Accordingly, the present invention provides a mower at the front of the fuselage.
In the direction opposite to the direction of grass ejection
Only when the vehicle turns in the opposite direction, the effective range of the axle brake with respect to the steering turning angle of the steered wheels is widened, and smooth switching to high-speed driving and steering are performed.

[0004]

SUMMARY OF THE INVENTION The invention is a steerable vehicle.
With rear wheels 2, 3 and unsteerable front wheels 10, 10,
Wheels 2, 3, 10, and 10 are driven when going straight to drive four wheels
It is configured to run in the state, the left and right lateral
A mower 20 having a grass spout on one side
Rear actuators that support the left and right rear wheels 2 and 3
The differential device 1 and the 2WD / 4WD
The switching clutch 4 and the steering differential shaft 8 that perform switching
One brake device is installed, and the
When turning the aircraft in the direction, first turn the rear wheel inside
Turn off the power transmission of 2 and rear right and left rear wheels 2 and 3 from 4WD to 2WD
After that, the brake is applied according to the steering angle of the rear wheel 2.
While operating the key device, gradually increase the rotation outside the turning
The tractor steering wheel drive device is provided with an interlocking mechanism 6 for operating the tractor.

[0005]

[Function] When mower 20 is attached to the front of the aircraft and goes straight
Is a four-wheel drive type in which front and rear wheels 2, 3, 10, and 10 are driven
Will be maintained. Normally, mower 20 is used to cut corners.
When running, do not run on the grass or grass
Swing the aircraft to the opposite side of the mower 20 grass outlet.
Mowing the grass, but in such a case,
The power transmission to the rear wheels is cut off, and the state changes from 4WD to 2WD.
And turn the steering wheel further inward
When operated, the interlocking mechanism 6 operates according to the steering angle of the rear wheel 6.
The braking is applied to the directional differential shaft 8, and the rotation of the rear wheel 3 outside the turning
Gradually rise. For this reason, even if there is a tree, a small radius
Can cut the area around trees .

[0006]

The present invention is constructed as described above.
The following technical effects are obtained. That is, the steerable rear wheels 2,
3 and unsteerable front wheels 10, 10;
All three, ten, and ten are driven when going straight, and are in a four-wheel drive state.
It is configured to run, and on the front part of the fuselage
Tractor connected to mower 20 having grass outlet
Rear axle hub that supports the left and right rear wheels 2 and 3
Switching between the differential device 1 and the 2WD / 4WD in the housing 33
A single brake for braking the switching clutch 4 and the steering differential shaft 8
Provide a rake device, in the direction opposite to the grass discharge direction
When the aircraft turns, first the rear wheel 2
Turn off the power transmission and change the rear wheels 2 and 3 from 4WD to 2WD
After that, according to the steering angle of the rear wheel 2, the braking device
And gradually increase the rotation outside the turn.
The aircraft in the opposite direction of the grass
When turning, the rear wheel 3 on the outside of turning turns
Rather than increase at a stroke compared to the rolling speed, first,
After passing through the state, the steering differential shaft 8 inside the turning is braked
The rotation of the rear wheel 3 outside the turning gradually increases
As it rises, the change in rotational speed outside the rear wheel is smooth
The aircraft can be turned smoothly without damaging the grassland.
Can be.

On the other hand, the aircraft is turned in the grass discharge direction,
The rotation speed of the rear wheel 2 outside the turning
Instead of turning in the normal four-wheel drive state
Therefore, the turning radius is larger than in the previous case,
Because the aircraft does not travel on the grass
It will not interfere with the recovery of grass and turf .

[0008]

1 to 6, a tractor body 9 has a driver's seat 11 and a steering handle 12 on the front wheels 10, 10 and an engine E on the rear, steered wheels 2, 3.
And the front wheel 1 is driven by the driving of the engine E.
It is a four-wheel drive mode in which the vehicle travels by driving 0, 10 and the steered wheels 2, 3. The car body 9 is
Clutch housing 1 having PTO clutch 13 and the like
4. A main transmission housing 15 having a hydraulic continuously variable transmission HST and the like, a transmission case 19 having an auxiliary transmission 16, a front wheel differential device 17, a PTO transmission 18 and the like are integrally connected to each other to form a front side of the vehicle body 9. This is an example in which the mower 20 is mounted to perform mower work. 21
Is a gauge wheel, and 22 is a transmission shaft that interlocks between the PTO shaft 23 at the front of the transmission case 19 and the input shaft 24 of the mower 20.

[0009] The traveling transmission mechanism comprises a traveling output shaft 25 constantly driven by an engine E, and a hydraulic continuously variable transmission HS.
The front axle 27 of the front axle housing 26 is transmitted through the T, the auxiliary transmission device 16, the differential device 17, and the like to drive and drive the front wheels 10 at both left and right ends. Among these, the hydraulic continuously variable transmission HST is capable of continuously changing the speed from the neutral position N to the forward high-speed position F or the reverse high-speed position R by operating the transmission lever or the transmission petal 28. Further, from the auxiliary transmission 16, the transmission shafts 29, 30 to the steered wheels 2, 3 side, the bevel pinion gear 31, the bevel wheel gear 32, and the like at the end of the transmission gears mesh with each other to transmit the differential device 1, and The left and right steered wheels 2, 3 can be driven from the differential device 1 via the steering differential shaft 8, which is a left and right rear axle in the rear axle housing 33. Between the transmission shafts 29 and 30, a full-time four WD3
6 is provided, and the drive-side transmission shaft 29 is
Transmission drive only when the rotation is higher than the transmission shaft 30 on the side,
Further, there is provided a lock mechanism for constantly switching the full-time four WD 36 to the interlocking fixed state.

[0010] A final case 37 is connected to the left and right ends of the rear axle housing 33, and the left and right opposed steering wheels 2, 3 are connected to the outer end of the final case 37.
A steering case 39 on which a wheel shaft 38 is mounted is supported so as to be steerable around a king pin 40, and the steering handle 12 is operated so as to be steered and linked via a power steering device, a tie rod or the like. Fork brake cams 41 and 42 are provided before and after the steering case 39 integrally rotates.

The steering differential shaft 8 on one side in the rear axle housing 33 is moved in the axial direction by a switching clutch 4 that is movable in the axial direction between the steering differential shaft 8 and a bevel gear 43 that is bearing in the final case 37. Power can be transmitted from the steering differential shaft 8 to the bevel gear 43. On the opposite side of the switching clutch 4 from the bevel gear 43, a disc brake 7 of a brake body 34 integrated with the steering differential shaft 8 is integrated.
4, and the movement of the switching clutch 4
After the switching clutch 4 is disengaged, a brake is applied to the steering differential shaft 8 to be fixed.

The interlocking of the switching clutch 4 having such a brake 7 by the brake cams 41 and 42 is performed by the interlocking mechanism 6.
A link rod 49 connects the distal ends of link arms 47 and 48 which are pivotally supported 45 and 46 to 3, and an elastic body 5 made of a suitable elastic leaf spring is fixed to the pivot shaft 45 on one end side. The roller 50 at the tip of the elastic body 5 is in contact with the brake cams 41 and 42. In addition, a shifter 51 that can move by engaging the switching clutch 4 is provided integrally with the pivot shaft portion 46 on the other end side, and the shifter 51 is always resiliently springed toward the entrance side of the switching clutch 4 by a spring 52. ing.

With such a configuration, the vehicle can turn by steering the rear steered wheels 2 and 3 with the steering handle 12. When the vehicle is traveling straight ahead, the roller 50 of the elastic body 5 is located in the valley between the brake cams 41 and 42, the switching clutch 4 is in the engaged state, and the bevel gear 8 43, the power transmitted to the bevel pinion gear 31 is transmitted via the differential device 1 to the left and right steered wheels 2, 3.
And the vehicle is driven in a four-wheel drive mode by the transmission of the front wheels 10.

When the steering wheel is turned, the steering wheels 2 and 3 rotate around the kingpin 40 to cause the brake cam 4 to rotate.
Since the brake cams 41 and 42 are rotated,
When the roller 50 located in the valley between 42 is pushed, the elastic body 5 is rotated around the pivot shaft portion 45, the switching clutch 4 is disengaged by the shifter 51, and the transmission of the bevel gear 43 is cut off. The steered wheels 2 are free to rotate. At the same time, almost no driving force is transmitted to the steered wheels 3 on the opposite side via the differential device 1. Therefore, at this time, the state is switched from the four-wheel drive state to the two-wheel drive state.

As the steering turn further proceeds, the brake 7 is moved together with the switching clutch 4 through the elasticity of the elastic body 5 so that the brake 7 is pressed against the brake seat 44 and the steered wheels 2 are moved. The side steering differential shaft 8 is elastically braked (FIG. 3). Since the rotation of the steering differential shaft 8 is reduced by the effect of the brake 7, the rotational speeds of the steering differential shaft 8 and the steering wheel 3 on this side via the differential device 1 are sequentially increased, and the rotation of the brake 7 is reduced. When the steering wheel 3 is pressed and fixed to the brake seat 44, the steered wheel 3 is driven at a rotational speed approximately twice as high as the rotational speed when the left and right steered wheels 2, 3 rotate simultaneously and travel straight. It becomes a three-wheel drive state. This facilitates turning. When the brake 7 is applied in this manner, the brake 7 is elastically applied via the elastic body 5 in accordance with the steering. Therefore, the brake operation range A for applying the brake can be set long, and the turning can be smoothly performed. Can be performed. When the steering turn is completed, the brake 7 is released, the switching clutch 4 is engaged, and the four-wheel drive state is established.

FIGS. 7 to 9 are different from the above example in that:
The switching clutch 4 is automatically turned on and off according to the relationship between the rotation speed of the steering differential shaft 8 and the rotation speed of the bevel gear 43 to switch between four-wheel drive and two-wheel drive. Further, at the time of the steering turn, the brake 34 is applied from the two-wheel drive state, thereby driving the steered wheel 3 on the opposite side at a double speed to facilitate the turn.

Between the switching clutch 4 and the bevel gear 43 on the steering wheel 2 side, there are clutch surfaces 55,
56 and inclined surfaces 53 and 54 that are inclined in the axial direction. When the switching clutch 4 rotates at a higher speed than the bevel gear 43, the clutch surface 55 engages with 56 to transmit the steered wheels 2. When the switching clutch 4 rotates at a lower speed than the bevel gear 43, the gap between the inclined surfaces 53 and 54 slides, and the transmission is switched to the two-wheel drive state without transmission. Since the switching clutch 4 is pushed toward the brake 7 against the spring 57, the brake surface 58 of the switching clutch 4
To brake the steering differential shaft 8. by this,
When the steering wheel 3 on the opposite side is transmitted at a high speed via the differential device 1 to be in a three-wheel drive state and the brake 7 is fixed, the steering wheel 3 is driven at double speed.

At the time of turning, if the slipping between the switching clutch 4 and the rotation of the steered wheels 2 becomes faster, the number of times of overtaking due to the sliding of the inclined surfaces 53 and 54 increases,
The effectiveness of the brake 7 also increases. Note that R1 is the turning radius of the tread center between the left and right front wheels 10 and 10 during steering turning, and R2 is the turning radius of the tread center between the steering wheels 2 and 3 in a relationship of R1 <R2. Turned.

As described above, the automatic switching between the four-wheel drive and the two-wheel drive is performed by the automatic switching of the switching clutch 4 at the time of forward traveling transmission, but in the reverse traveling, the switching between the switching clutch 4 and the traveling differential shaft 8 is performed. Between them, a ratchet mechanism 59 is provided, and when the traveling differential shaft 8 rotates in the reverse direction,
No driving force is transmitted to the switching clutch 4. Therefore, the brake 7 does not work in the steering turning during the reverse running.

[Brief description of the drawings]

FIG. 1 is a plan view of a steering wheel and a rear axle housing.

FIG. 2 is a plan sectional view of a part thereof.

FIG. 3 is a graph showing a braking action.

FIG. 4 is a side view showing the transmission of the tractor.

FIG. 5 is a side view of the tractor mower.

FIG. 6 is a plan view thereof.

FIG. 7 is a plan cross-sectional view of a rear axle housing showing another embodiment.

FIG. 8 is an enlarged plan sectional view of a part thereof.

FIG. 9 is a plan view showing the operation of the tractor.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Differential device 2 Steering wheel 3 Steering wheel 4 Switching clutch 5 Elastic body 6 Interlocking mechanism 7 Brake 8 Steering differential shaft

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-2-57484 (JP, A) JP-A-59-216730 (JP, A) JP-A 63-160270 (JP, U) JP-A 53-160270 15247 (JP, U) Fully open sho 61-37078 (JP, U) Fully open sho 54-112237 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) B62D 11/00

Claims (1)

(57) [Claims] 1. Steerable rear wheels 2, 3 and non-steerable front wheels
With front and rear wheels 2,3,10,10
Drives when traveling and runs in a four-wheel drive state
The front of the aircraft has a grass outlet on one side in the horizontal direction.
In the tractor to which the mower 20 is connected
The rear axle housing 33 supporting the wheels 2 and 3
Device 1 and a switching clutch 4 for switching between two-wheel drive and four-wheel drive
And a single braking device for braking the steering differential shaft 8,
When the aircraft was turned in the direction opposite to the direction of the grass
First, turn off the power transmission of the rear wheel 2 inside the turning
The rear wheels 2, 3 from 4WD to 2WD, then
Turn the brake device while operating the brake device according to the steering angle of the wheel 2.
An interlocking mechanism 6 that gradually raises the outward rotation
A tractor steering wheel drive device characterized by the following .