JPH0735779Y2 - Cushion structure in speed ratio switching mechanism of steering wheel speed increasing device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Field of Industrial Application The present invention relates to a shock absorbing structure in a speed ratio switching mechanism of a steering wheel speed increasing device.

(B) Conventional technology Conventionally, for example, in a four-wheel drive vehicle such as an agricultural tractor, even though the path length of the steered wheels (front wheels) becomes longer than that of the rear wheels due to an inner wheel difference when turning, etc. Since it is driven at high speed, there is a drawback that it is difficult to make a sharp turn, and in order to eliminate this drawback, a speed increasing device that can switch the speed ratio is interposed between the final drive device of the front wheels and the front propeller shaft. When the steering wheel is steered by a large amount, the speed ratio switching mechanism operates to switch the speed increasing device to the speed increasing state, thereby eliminating the difficulty of sharp turning due to the difference in the path length. There is.

(C) Problems to be solved by the device However, the speed ratio switching mechanism is interlocked with the steering wheel, and it is the speed ratio switching mechanism that keeps the steering wheel speed increasing device in a constant speed operation state at a small steering angle. This can be easily solved by providing play in the mechanism, but if the steering gear is switched to the speed increasing side at a large steering angle and the steering wheel is rotated further, The operation of the ratio switching mechanism causes an overstroke with respect to the speed increasing device, and there is a possibility that both the speed increasing device and the switching mechanism are unduly applied with force and damaged.

(D) Means for Solving the Problems According to the present invention, the front wheels can be driven and steered, and the steering wheel speed-increasing device, which is composed of a plurality of friction plates and a differential gear mechanism and is capable of speed ratio switching, is operated. The push lever that is interlocked with the directional mechanism pushes the switch lever of the speed increasing device to rotate it,
The speed of the input gear of the differential gear mechanism is reduced and the speed of the output gear is increased by the pressure contact force of the friction plates to increase the speed of the output gear linearly from the constant speed operating state to the speed increasing operating state. In the speed ratio switching mechanism configured to switch to
A push rod is slidably inserted into the tip of the switching lever, and a spring receiver, a spring, and a thrust washer are loosely fitted to the rod from the switching lever side in the above order.
The thrust washer is screwed to the push rod, and is fixed by an adjusting mechanism composed of a double nut capable of adjusting the switching start position of the switching lever, and is a buffer in the speed ratio switching mechanism of the steering wheel speed increasing device. It is intended to provide structure.

(E) Action / Effect According to this invention, the push rod of the speed ratio switching mechanism is
It is configured to switch from the constant speed operation state that was held until then to the speed increasing operation state by push operation, and the push operation of the push rod is that the rod is loosely fitted in the switching lever of the speed increasing device. Is transmitted from a double nut (an adjusting mechanism of the switching lever switching start position) screwed to the push rod, the thrust washer, the spring, and the spring receiving body in this order, and is transmitted from the receiving body to the switching lever of the speed increasing device. .

Therefore, even if the push rod of the speed ratio switching mechanism overstrokes, it is absorbed by the spring, and the speed increasing device and the speed ratio switching mechanism are not overpowered.

Also, by using the double nut to transmit the pressing force to the spring, pre-load can be applied to the spring at the time of assembly by tightening the double nut, which simplifies the work. The operation start point and the transmission pressing force can be easily adjusted by changing the position of the double nut.

Also, when the steering mechanism is used to make a turning operation during low-speed traveling such as when traveling in the field or when traveling at an inclined contour line, the front wheels can be accelerated by the steering wheel speed-increasing device, and the aircraft can make a small turn. At this time, due to the cushioning structure, it is possible to absorb the sudden steering transmission force even when the steering is steeply turned.

At the same time, when the steering wheel speed increasing device, which is composed of a plurality of friction plates and a differential gear mechanism and is capable of speed ratio switching, applies pressure contact force to the plurality of friction plates in accordance with the steering angle of the steering wheel, the operating gears are activated. Due to the characteristic that the sum of the rotation speeds of the input gear and output gear of the mechanism is constant, the rotation speed of the input gear of the operating gear mechanism decreases linearly according to the applied pressure contact force, and the rotation of the output gear By increasing the number, the front wheels can be gradually and linearly increased in a stepless manner, and a turning operation with a soft feel for the operator can be performed.

(F) Embodiments An embodiment of the present invention will be described in detail with reference to the drawings. In FIG. 5, A indicates a four-wheel drive tractor, and the clutch housing 2 is driven by power from an engine portion 1 provided at a front portion of the fuselage. The left and right rear wheels 4 arranged on the left and right sides of the case 3 via the mission case 3 are driven, and the left and right front wheels are extended via the front propeller shaft 5 extending in front of the mission case 3 and the final drive device 6. The steering wheel 8 provided on the rear side of the engine unit 1 steers the left and right front wheels 7.

Incidentally, a differential device for distributing power to the front and rear wheels 7, 4, so-called center differential, is not equipped with importance placed on straightness during work steering.

Between the front propeller shaft 5 and the final drive device 6 for the front wheels 7, as shown in FIG. 3, bevel gears 9a, 9b, 9c and 9d as a differential gear mechanism are used. A steering wheel speed increasing device 9 capable of switching the speed ratio is provided.

That is, by connecting the bevel gear 9d with the input shaft 11 connected with the front propeller shaft 5 by the dog clutch 10, the bevel gear 9a connected with the final drive device 6 transmits power at a rotational speed equal to that of the front propeller shaft 5. I am trying to do it.

Further, as is well known, the differential gear mechanism has a characteristic that the sum of the rotational speeds of the input side gear and the output side gear is constant, so that the bevel gear 9d is provided with a large number of friction plates, that is, a wet multi-plate type. By fixing the same to the case 13 of the speed increasing device 9 with the brake 12 of the final drive device 6 via the bevel gear 9a.
In addition, the power is transmitted at a maximum double the rotation speed.

Then, the speed ratio switching differential described above has one tooth 10 of the dog clutch 10 at one end of the slider 14 fitted onto the input shaft 11.
a is formed and a pressure plate 12a of the brake 12 is formed at the other end, and the slider 14 is moved by the operation of the shift fork 15a fixed to the shift shaft 15 through which the case 13 is inserted.

In the figure, reference numeral 16 denotes a return spring for urging the slider 14 in the direction of the dog clutch 10 to maintain a constant speed operation state.

A switching lever 17 is fixed to the end of the shift shaft 15 protruding outside the case 13, as shown in FIGS. 1 and 2, and is pivotally attached to the tip of the lever 17. A tip end of a push rod 20 of a speed ratio switching mechanism 19 is slidably inserted into a joint metal fitting 18 and a shift shaft 15 is rotated by pushing the rod 20.

A substantially triangular cam plate 23 is fixed to the base end of the push rod 20, and an intermediate shaft 22 linked to the pitman arm 21a of the steering gear box 21 is inserted into a recess 23a formed in the plate 23. And the upper and lower cam plates of the cam plate 23
The upper and lower cam rollers 29a, 29b axially supported by the intermediate shaft 22 at a predetermined distance from the intermediate shaft 22 when the steering wheel 8 is set to a large steering angle are pressed by the rotation of the intermediate shaft 22. The push rod 20 is pushed.

The steering mechanism S includes a steering wheel 8, a steering gear box 21, a pitman arm 21a, and an intermediate shaft 2.
2. It is composed of an intermediate link 33 and a drag rod 34.

With the above configuration, when the steering mechanism S makes a turning operation during low-speed traveling such as field traveling or slope contour traveling, the front wheels 7 can be accelerated by the steering wheel speed increasing device 9.
It is possible to make a small turning of the machine body, and at this time, it is possible to absorb a sudden steering transmission force even when the steering is rapidly turned.

At the same time, the steerable wheel speed increasing device 9 composed of a wet multi-plate type brake 12 and a differential gear mechanism and capable of switching the speed ratio gradually and linearly steplessly in accordance with the steering angle of the steering wheel 8. Since the speed can be increased, the operator can perform a turning operation with a soft feel.

The push rod 20 is provided with a buffer structure M. In the structure M, the spring receiver 24, the spring 25, and the thrust washer 26 are loosely fitted to the rod 20 from the switching lever 17 side in the above order, The washer 26 is screwed to the push rod 20 and fixed with the double nut 27 that can adjust the switching start position, and the push rod 20 is pushed by the double nut.
27, the thrust washer 26, the spring 25, and the spring receiver 24 are used for transmission to the switching bar 17.

Further, the outer circumferences of the spring receiver 24, the spring 25, and the thrust washer 26 are covered with a cylindrical sleeve 28, and a locking portion 28a is provided on the inner peripheral surface of the end of the sleeve 28 on the spring receiver 24 side. Then, the retaining ring for hole 28b is fitted on the inner peripheral surface of the end portion on the thrust washer 26 side to preload the spring 25. The spring 25 can be used by stacking a large number of disc springs in addition to the coil spring.

Further, the upper and lower cam rollers 29a, 29b are pivotally supported by a roller support plate 31 projecting from a pipe shaft 30 spline-fitted to the intermediate shaft 22, and the auxiliary transmission high / low switching lever provided with the pipe shaft 30 in the operating part. By sliding the wire 32 connected to (not shown) in the axial direction so that the upper and lower cam rollers 29a, 29b do not contact the upper and lower cam surfaces 23b, 23c, the steering wheel speed-up operation is increased. , The sub transmission is operated only when the low speed state is set.

In the figure, 33 is an intermediate link connecting the pitman arm 21a and the intermediate shaft 22, and 35 is a return spring for the tube shaft 30.

With the buffer structure M having the above-described structure, the push rod 20 of the speed ratio switching mechanism 19 absorbs the overload accompanying the speed increase, and even if the push rod 20 overstrokes, it is absorbed by the spring 25 and the steering wheel increases. The speed device 9 and the speed ratio switching mechanism 19 will not be overloaded.

In addition, the structure described above simplifies the buffer structure M,
It is also easy to apply a preload by tightening the double nut that adjusts the switching position, and it is also easy to adjust the speed increase switching operation starting point and the transmission pressing force.

[Brief description of drawings]

FIG. 1 is a side view of a buffer structure according to the present invention (cross section of a main part). FIG. 2 is a plan view of the same. FIG. 3 is a vertical sectional view of the steering wheel speed increasing device. FIG. 4 is a side view of the steering mechanism. FIG. 5 is an overall side view of an agricultural tractor having the structure of the present invention. S: Steering mechanism 4: Rear wheel 5: Front propeller shaft 6: Final drive device 7: Front wheel 9: Directional wheel speed increasing device 17: Switching lever 20: Push rod 24: Spring receiver 25: Spring 26: Thrust washer 28 :sleeve

Claims (1)

[Scope of utility model registration request] 1. A steering mechanism (S) via a steering wheel speed increasing device (9) capable of driving and steering front wheels (7) and comprising a plurality of friction plates and a differential gear mechanism capable of speed ratio switching. ), The switching lever (17) of the speed increasing device (9) is rotated by the push operation of the push rod (20) interlockingly connected to the input gear of the differential gear mechanism. A speed ratio switching mechanism (19) configured to linearly switch the speed increasing device (9) from a constant speed operating state to a speed increasing operating state by decreasing the number and increasing the rotational speed of the output side gear, The push rod (20) is slidably inserted into the tip of the switching lever (17), and the switching lever (17) is attached to the rod (20).
From the side, the spring receiver (24), the spring (25), and the thrust washer (26) are loosely fitted in the above order, and the thrust washer (26) is screwed to the push rod (20).
A buffer structure for a speed ratio switching mechanism of a steering wheel speed increasing device, characterized in that the switching lever (17) is fixed by an adjusting mechanism (27) composed of a double nut capable of adjusting a switching start position.