JP3022427B2 - Power transmission device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power transmission device, and can be used, for example, for a front wheel drive device of an agricultural tractor or the like.

[0002]

2. Description of the Related Art When turning an agricultural tractor in a field, it is desirable to improve the working efficiency and to turn the body with a small radius without damaging the field. In addition, in order to obtain a large thrust in a field where the ground is soft, it is better to drive the aircraft with four-wheel drive than with two-wheel drive. For this reason, conventionally, in a four-wheel drive type agricultural tractor, a front wheel speed increasing device is provided in a front wheel drive system, and the front wheel speed increasing device is switched to a low speed side when going straight, and is switched to a high speed side when turning, so that the peripheral speed of the front wheel is increased. A tractor with a so-called double speed mechanism that is configured to reduce the turning time and turning radius has appeared.

[0003]

In the conventional apparatus described above, the turning speed of the front wheels is increased at the time of turning to reduce the turning radius of the body, but a shock occurs when the front wheel speed increasing device is switched. There is a problem that the front wheels scratch the ground and become rough because the front wheels accelerated and drag the rear wheels to travel.

[0004]

SUMMARY OF THE INVENTION The present invention has been proposed in view of the above-mentioned problems, and has the following technical features.
He took the hand stage. That is, the driving side rotating body 65 and the driven side rotating body 75 are on the same axis, and the driving side rotating body 6
In a power transmission device provided with a driven-side rotating body 75 on an extension line of the axis 5 of FIG. 5, an uneven cam portion 65a is provided at a portion of the driving-side rotating body 65 facing the driven rotating body 75, A driven ring body 72 having an uneven cam portion 72a between the rotating body 65 and the driven side rotating body 75 is used as a shaft.
It is provided in an idle state so that the rotational power is transmitted from the drive side rotating body 65 side to the driven ring body 72 side by engagement of the two cam portions 65a, 72a, and the driven ring body 72 and the driven side rotating body 75 Locking pawl 7 that can be disengaged and transmit power
2b and 75b are provided, and the cam portion 65a of the driving-side rotating body 65 is provided.
Is the cam portion 7 of the driven ring body 72 during forward rotation or reverse rotation.
2a, the engaging pawls 72b and 75b are engaged with each other, and the driven rotator 75 is forcibly driven.
When the rotation speed of the driven-side rotator 75 exceeds the rotation speed of the drive-side rotator 65 due to the preceding rotation of the driven ring member 72, the driven ring member 72 is moved to the drive-side rotator 65 by the urging means 78 so that the locking claws 72b, 75b The power transmission device is characterized in that the meshing between them is released and the rotational driving force to the driven-side rotating body 75 is cut off.

[0005]

Embodiments of the present invention will be described below with reference to the embodiments shown in the drawings. First, the structure will be described.
Has a front wheel 2, 2 and a rear wheel 3, 3 at the front and rear of the body, respectively, as a traveling device, and has an engine 4 mounted at the front of the body and a clutch housing 5 connected to the rear. The clutch 6 in the clutch housing 5 is disengaged by depressing the clutch pedal 7, and prevents transmission of power to the transmission described below.

A forward / reverse switching mechanism 10 is accommodated in the rear surface of the clutch housing 5. When the forward / backward switching lever (not shown) is tilted forward, the fuselage moves forward. That is, a synchromesh type forward / reverse switching transmission 13 is provided on the transmission shaft 12, and when the shift fork is operated to move the sleeve 14 to the front side, the gear 16 on the forward rotation rotates the transmission shaft 12 The power in the forward direction is transmitted to the transmission shaft 12 via the gear 17 formed at the end of the clutch shaft 8 and the gear 16 on the transmission shaft 12.

When the sleeve 14 is moved rearward, the gear 16 is rotated by a large-diameter gear 20 of a counter shaft 18 suspended below the transmission shaft 12 and a small-diameter gear 21 at the rear of the counter shaft 18. Is transmitted to a gear 22 on the transmission shaft 12 via a back counter-gear (not shown) sequentially, and the gear 22 is directly connected to the transmission shaft 12 to transmit power in the reverse direction.

The transmission shaft 12 is a cylindrical coupler-2.
4 and is interlockingly connected to an input shaft 26 protruding from a front transmission case 25 via the front transmission case 4. A drive pinion 28 is coaxially mounted behind the input shaft 26, and a main transmission including a large-diameter gear 29 a, a medium-diameter gear 29 b, a small-diameter gear 29 c, and a pawl 29 d is provided at the front of the drive pinion 28. A counter gear 29 is freely rotatably fitted.

Reference numeral 33 denotes a cylindrical boss behind and spline-fitted to the drive pinion 28. A sliding gear 35 is spline-fitted on the boss 33 so as to be movable in the forward and backward directions. Reference numeral 36 denotes a sub-transmission gear loosely fitted to the drive pinion 28, and has a claw portion 36a at the forefront. A gear 38 for taking out front wheel power is spline-fitted to the drive pinion 28 at the rear of the gear 36 for the auxiliary transmission.

On the other hand, a PTO counter disposed below the drive pinion 28 and disposed along the front-rear direction.
The shaft 40 is operatively connected to the counter-shaft 18 via two cylindrical couplings 41, 42 and the like.
A boss 45 is freely rotatably fitted to a front portion of the PTO counter shaft 40 located in the rear transmission case 44, and a gear 47 is spline-fitted to the front portion of the boss 45.

The gear 47 always meshes with a gear 49 formed at the rear end of the input shaft 26. Also,
Two gears 50 and 51 are rotatably and loosely fitted on the front and rear of the boss 45, and claw portions 50a and 51a are formed at the rear of the gears 50 and 51, respectively.
Is designed to always mesh with the large-diameter gear 29a of the main transmission counter-gear 29, and the rear gear 51 is always meshed with the medium-diameter gear 29b.

A counter gear 54 having two large and small gears 52 and 53 is loosely fitted on the PTO counter shaft 40 at the rear portion of the boss 45, and the large diameter gear 52 is used as the small diameter of the main transmission counter gear 29. The rear small-diameter gear 53 is always meshed with the sub-transmission gear 36. The shifter on the boss 45
When the gear 56 is moved forward from the state shown in FIG. 3 to connect the boss 45 and the gear 50, "1st speed" of the main transmission is obtained. When the shifter 57 is moved forward from the state shown in FIG.
5 and the gear 51 are connected to obtain the second speed of the main speed change,
By connecting the boss 45 and the large-diameter gear 52 by moving the shifter 57 backward, the third speed is obtained. At this time, if the sliding gear 35 is moved to the front side to connect the claw portion 29d of the main transmission counter-gear 29 and the boss 33, the auxiliary transmission becomes "high speed". Is moved to the rear side to connect the boss 33 and the claw portion 36a of the sub-transmission gear 36, thereby obtaining the "low speed" of the sub-transmission.

In this embodiment, the combination of the main transmission and the auxiliary transmission enables a six-speed shift in forward and backward traveling, and the rotational power reduced here is transmitted to the differential gear of the rear wheels 3, 3. (Not shown) to rotate the rear wheels 3, 3.
Next, the front wheel drive system will be described. A gear 60 is freely rotatably fitted to the rear end of the counter gear 54 loosely fitted on the PTO counter-shaft 40, and the gear 60 is configured to mesh with the front wheel power takeout gear 38, It is also configured to mesh with a front wheel drive gear 62 which is mounted on a lower portion of the rear transmission case 44. 6
3 and 64 are bearings for supporting the front wheel drive gear 62. A drive ring body 65 is provided integrally with a front portion of the front wheel drive gear 62 which is a drive body, and a mountain-shaped cam portion 65a including a plurality of uneven portions is provided on the front side thereof.

Reference numeral 67 denotes a driven-side first shaft which is coaxial with the front wheel driving gear 62 and disposed in front of the front wheel driving gear 62. The rear shaft end of the first shaft 67 is formed on the front wheel driving gear 62. The shaft hole 68 is loosely fitted. Reference numeral 70 denotes a cylindrical rotating body provided so as to cover a portion where the front wheel drive gear 62 and the first drive shaft 67 overlap, and is driven to rotate by the drive ring body 65.

Reference numeral 72 denotes a driven ring member that is rotated by the driving ring member 65 in the rotating member 70,
A cam portion 72a made of a mountain-shaped cam surface made up of a plurality of uneven portions is provided on the outer peripheral portion of the rear surface. This cam 72
a and the cam portion 65a of the drive ring body 65 transmit power while meshing with each other with a gap capable of slightly moving in the axial direction and the rotational direction.

Further, a clutch pawl 72b is provided on the outer periphery of the front side of the driven ring body 72 on the front side. 75 is the first shaft 67
Is a driven piece that is spline-fitted to the shaft end, and a clutch claw 75b is formed on the outer periphery of the rear surface. When the clutch pawl 72b of the driven ring body 72 and the clutch pawl 75b of the driven piece 75 are engaged, the front wheel drive gear 62
Is transmitted to the first shaft 67 via the driven piece 75, but when this engagement is disengaged, the first shaft 67 is in a free rotation state, and the front wheel drive gear 62 on the drive side is driven.
Power is not transmitted. A spring 78 is provided in the rotating body 70 and provided between the inner wall thereof and the driven ring body 72, and constantly biases the driven ring body 72 rearward.

Reference numeral 80 denotes a receiving portion which is fitted to the small diameter portion of the rotating body 70, and one end of which is provided on the wall 44 of the rear transmission case 44.
a for locking. 82 is the rotating body 7
0 is a braking piece that penetrates in the front-rear direction and has a rear end portion integrally fixed to the driven ring body 72. A gap 70a is provided in which 82 can move slightly in the circumferential direction. A ring-shaped spring 85 is wound around the outer periphery of the front end of the braking piece 82 via a brake 85a.

When the front wheel drive gear 62 is rotating in the normal rotation direction (body forward direction), the rotational difference between the drive side front wheel drive gear 62 and the driven first shaft 67 is reduced. Does not occur, the rotational power of the front wheel drive gear 62 is supplied to the cam portion 65a of the drive ring body 65 and the driven ring body 7
2 cam portion 72a, clutch pawl 72 of driven ring body 72
b, the torque is transmitted to the first shaft 67 via the clutch pawl 75b of the driven piece 75 in sequence.
When the rotation on the shaft 67 side becomes faster than the rotation speed on the front wheel drive gear 62 side, the cam portion 65a of the drive ring body 65
In the rotational direction, a gap is formed between the driven ring body 72 and the cam portion 72a of the driven ring body 72, so that the driven ring body 72 is pushed backward by the spring 78, and the clutch pawl 72b of the driven ring body 72 and the clutch of the driven piece 75 The engagement with the pawl 75b is released, and the transmission of power is temporarily stopped.

That is, power is not transmitted from the front wheel drive gear 62 to the first shaft 67, which is the driven side. The same applies to the case where the body retreats. When the rotation of the first shaft 67 becomes faster than the front wheel drive gear 62 side, power is not transmitted to the first shaft 67 side, and therefore, the rear wheel drive is temporarily stopped. State.

In this embodiment, the driving ring 6
5, the rotating body 70, the driven ring body 72, the driven body 75, and the like are collectively referred to as a clutch mechanism 90. Next, the front wheel speed increasing mechanism 95 housed in the front transmission case 25 will be described. 96 is an input gear, bearing 97,
At 98, it is pivotally supported on the wall 100.

Reference numeral 101 denotes a second shaft provided at the front of the first shaft 67. The rear end of the second shaft 101 is supported by an input gear 96 via a bearing 102, and the front end of the front transmission case 25 is supported by a bearing 103. It is supported by the front wall.
Numeral 105 denotes a cylindrical rotary drum fixed to the second drive shaft 101.
06 and 107 are provided.

Reference numeral 108 denotes a disc spring for pressing the rear friction clutch unit 107, and reference numeral 109 denotes a front friction clutch unit 1.
06. 110 is the second axis 101
The counter-shaft 110 is provided with gears 111 and 112 before and after the counter-shaft 110.
Is fixed. The rear gear 111 meshes with the input gear 96, and the front gear 112 meshes with the gear 113 loosely fitted on the second shaft 101.

When the body is moving straight, the rear friction clutch portion 107 is constantly pressed, so that the first shaft 6
7 is driven by the input gear 96 and the friction clutch unit 10.
7, transmitted to the second shaft 101 via the rotating drum 105. In this case, the gear ratio of each transmission gear is set so that the peripheral speed of the front wheels 2 and 2 and the peripheral speed of the rear wheels 3 and 3 are substantially the same. When the steering wheel 118 is turned to operate the front wheels 2 and 2 by a predetermined angle or more to turn the body, the piston 1
09 is pushed forward and the friction clutch unit 106 on the front side
Is connected, and the rear friction clutch unit 107 is free.

In this case, the ratio of the speed increase by the front wheel speed-up mechanism 95 is such that the peripheral speed of the front wheels 2 and 2 is higher than the peripheral speed of the rear wheels 3 and 3, specifically, the peripheral speed ratio is 1.4. It is desirable to set a gear ratio such that the speed is increased about twice. In the figure, reference numeral 120 denotes a third drive shaft connected to the second shaft 101 for driving a front wheel differential (not shown), and 122 denotes a shaft cover.
It is.

In the above example, when the tractor-1 travels in the field, if the vehicle is traveling straight, the front wheel speed increasing mechanism 9
0 indicates a standard four-wheel drive state, that is, a state in which the peripheral speed ratio between the front and rear wheels 2 and 3 is substantially constant, and the aircraft travels. When the front wheels 2, 2 are steered by turning the steering handle 118 at a predetermined angle or more to turn the fuselage on the ridge, the state is switched from the standard 4WD state to the speed increasing state, and the peripheral speed of the front wheels 2, 2 is reduced. The speed is increased to about 1.4 times the peripheral speed of the rear wheels 3,3.

When the peripheral speeds of the front and rear wheels 2 and 3 are changed from approximately the same speed to approximately 1.4 times, in the case of the conventional device, the peripheral speeds of the front wheels 2 and 2 are set at a predetermined front wheel steering angle. At a stretch, so that in a tractor in which both the front and rear wheels are driven, the peripheral speed of the front wheels 2, 2 with respect to the rear wheels 3, 3 can only be about 1.0 times or 1.4 times. However, in the device shown in this embodiment, since the clutch mechanism 90 is provided in front of the front wheel speed-up mechanism 95, the front wheels 2,
When the peripheral speed of the front wheels 2, 2 changes from 1.0 times to 1.4 times and the front wheels 2, 2 try to increase in speed due to the reaction force from the ground, the driving of the front wheels 2, 2 is released. As a result, a state in which only the rear wheels 3, 3 are driven occurs, and as a result, a section is created in which the peripheral speed of the front wheels 2, 2 is gradually increased in a range of about 1.0 to 1.4 times or less, The speed increase of the front wheels 2, 2 can be smoothly performed without shock.

At this time, the peripheral speed of the front wheels 2 and 2 gradually increases, and power is transmitted smoothly, so that the front wheels 2 and 2 do not scratch the ground and roughen the field, so that turning is easy. Become. Further, when the driver makes a comfortable turn by stepping on one brake, the front wheels 2 and 2 receive the ground resistance from the ground.
Tends to rotate at a peripheral speed of 1.4 times or more. In such a case, the clutch mechanism 90 provided in front of the front wheel speed-up mechanism 95 operates to operate the front wheels 2 and 2 Is not transmitted to the vehicle and the body is turned only by driving the rear wheels 3 and 3, so that the so-called pushing action of the front wheels 2 and 2 is eliminated, and the front wheels 2 and 2 simply roll. Does not destroy the field.

[0028]

As described above, according to the present invention, the rotating body 65 on the driving side and the rotating body 75 on the driven side are on the same axis, and the rotating body 65 on the driven side is extended along the axis of the rotating body 65 on the driving side. Rotating body 7
In the power transmission device provided with the rotator 5, an uneven cam portion 65 a is provided at a portion of the drive-side rotator 65 facing the driven rotator 75 side, and the drive-side rotator 65 and the driven rotator 7 are provided.
5, a driven ring body 72 having an uneven cam portion 72a is provided on the shaft in a free-rotating manner, and the two cam portions 65a, 72a
The rotational force is transmitted from the drive side rotating body 65 side to the driven ring body 72 side by the meshing, and furthermore, the driven claw 72b capable of engaging and disengaging and transmitting the power to the driven ring body 72 and the driven side rotating body 75. , 75b, and the driving-side rotator 65
When the cam portion 65a presses the cam portion 72a of the driven ring body 72 at the time of forward rotation or reverse rotation, the locking claw 72b,
When the driven rotator 75 is forcibly driven by the engagement of the driven ring 75b and the rotation speed of the driven rotator 75 exceeds the rotation speed of the drive rotator 65 due to the preceding rotation of the driven rotator 75, the driven ring member is 72 is moved to the driving side rotating body 65 side to disengage the locking claws 72b and 75b from each other and the rotational driving force to the driven side rotating body 75 is cut off, so that the driven side rotating body 75 is driven. When the rotating body 65 is rotated faster than the rotating body 65 on the side, the driving force to the driven rotating body 75 is cut off, and an excessive load is not applied to the power transmission system. In addition, this device is not only at the time of the normal rotation, Ru convenient der so acts as a one-way clutch even at the time of reversal.
Further, the driven ring body 72 is provided on the shaft body in a free running manner.
Therefore, the movement in the axial direction is smooth, and it can be stored compactly in the transmission case.

In particular, when this device is used as a front wheel drive device for an agricultural tractor, the front wheels do not brake with respect to the rear wheels in both forward turning and reverse turning.
Small turning is possible.

[Brief description of the drawings]

FIG. 1 is an overall side view.

FIG. 2 is a sectional view of a mission.

FIG. 3 is a sectional view of a mission.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 tractor 2 front wheel 3 rear wheel 4 engine 10 forward / reverse switching device 25 front transmission case 28 drive pinion 38 front wheel power take-out device 44 rear transmission case 62 drive body (front wheel drive gear) 65 drive ring body 65a cam Part 67 Follower (first shaft) 72 Follower ring 72a Cam portion 72b Locking claw 75 Driven rotor 75b Locking claw 78 Energizing means (spring) 90 Front wheel speed control mechanism 95 Front wheel speed increasing mechanism

Claims (1)

(57) [Claims] 1. A rotating body 65 on the driving side and a rotating body 7 on the driven side.
5 is on the same axis, and a driven side rotating body 75 is provided on an extension of the axis of the driven side rotating body 65 in the power transmission device.
An uneven cam portion 65a is provided at a portion facing the side, and a driven ring body 72 having an uneven cam portion 72a between the driving side rotating body 65 and the driven side rotating body 75 is idled around a shaft. The cam portions 65a, 72a are engaged to transmit rotational power from the drive side rotating body 65 side to the driven ring body 72 side, and further to the driven ring body 72 and the driven side rotating body 75. Are locking pawls 72b, 7 that can be disengaged and transmit power.
5b is provided, and when the cam portion 65a of the driving-side rotating body 65 presses the cam portion 72a of the driven ring body 72 at the time of forward rotation or reverse rotation, the locking claws 72b and 75b engage with each other, and the driven rotating body 75 is forcibly driven. The rotation speed of the driven-side rotator 75 is increased by the preceding rotation of the driven-side rotator 75.
When the rotation speed exceeds 5, the urging means 78 moves the driven ring body 72 toward the driving-side rotating body 65, and
A power transmission device characterized in that the engagement between the b and 75b is released and the rotational driving force to the driven side rotating body 75 is cut off.