JP2721085B2 - Travel transmission structure of work vehicle - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a traveling transmission structure for a working vehicle having a pair of left and right traveling devices of a crawler type or a multi-wheel type.

[0002]

2. Description of the Related Art As an example of the work vehicle described above, there is a combine having a pair of right and left crawler type traveling devices. An example of the traveling transmission structure is disclosed in Japanese Patent Application Laid-Open No. 3-204379. In this structure, a pair of left and right side gears for transmitting power to each of the left and right traveling devices is provided, a first transmission gear and a second transmission gear are arranged for the left and right side gears, and the left and right side gears are connected to the first transmission gear. The slide operation can be performed independently of each other over a position engaging with the second transmission gear and a position engaging with the second transmission gear. The power from the engine is transmitted to the first transmission gear as forward rotation power via a transmission (11 in FIG. 2 of the above publication), and the power from the transmission is transmitted to a transmission shaft (FIG. 2 of the above publication). 15), and transmitted as a reduced forward rotation power to the second transmission gear via a chain reduction mechanism (17 in FIG. 2 of the above-mentioned publication) and a transmission shaft (16 of FIG. 2 of the above-mentioned publication).

[0003] With the above structure, when the left and right side gears are brought into mesh with the first transmission gear, the left and right traveling devices are driven to rotate forward at the same speed, and the body moves straight. When the left side gear is engaged with the second transmission gear as shown in FIG. 2 of the above publication, the left traveling device is driven to rotate forward at a lower speed than the right traveling device, and the left and right traveling devices are driven. The aircraft turns left and turns based on the speed difference.

[0004]

As described above, in the case of changing the direction of the fuselage by decelerating one of the traveling devices and changing the direction of the fuselage, the second transmission transmits the forward rotation power decelerated by the chain reduction mechanism. To the gear. And in order to make sure the aircraft turns even on soft ground,
It is preferable that the difference between the driving speeds of the left and right traveling devices is large, that is, that the forward rotation power to one traveling device is sufficiently reduced. However, in the above-described structure, the reduction ratio of the chain reduction mechanism corresponds to the reduced forward rotation power, and only the gear ratio between the upper sprocket and the lower sprocket in the chain reduction mechanism, The overall reduction ratio (decelerated forward power) is determined.
Since the space for winding the chain is required, the outer diameter of the lower sprocket cannot be made sufficiently large due to restrictions from other parts. Accordingly, it is difficult to sufficiently increase the reduction ratio of the chain reduction mechanism, that is, when transmitting the forward rotation power for turning to the second transmission gear, it is difficult to transmit the sufficiently reduced forward rotation power. Therefore, in order to sufficiently reduce the forward rotation power, it is necessary to enlarge the outside of the transmission case or the like and increase the outer diameter of the lower sprocket in the chain reduction mechanism. According to the present invention, when transmitting the forward rotation power for turning to one traveling device, the sufficiently decelerated forward rotation power is transmitted to the one traveling device without increasing the size of an existing transmission case or the like. It is intended to be configured to be able to.

[0005]

A feature of the present invention resides in that the following structure is provided in the traveling power transmission structure for a working vehicle as described above. That is, the second transmission gear is rotatably fitted to the transmission shaft which fixedly supports the first transmission gear to which the forward rotation power for straight traveling is transmitted, and transmits the power to each of the pair of left and right traveling devices. A pair of left and right side gears are slidably operable and relatively rotatable over a transmission shaft between an interlocking connection position with the first transmission gear and an interlocking connection position with the second transmission gear, and an end of the transmission shaft. Output gear fixed to the output gear, a large-diameter third transmission gear meshing with the output gear, a transmission shaft supporting the third transmission gear, and the power of this transmission shaft being transmitted to the second transmission gear.
A fourth transmission gear having a small diameter for transmitting to the transmission gear;
It is configured to convert the forward rotation power transmitted to the transmission gear into reduced forward rotation power and transmit it to the second transmission gear.

[0006]

With the construction described above, for example, as shown in FIG. 1, the forward rotation power for straight traveling transmitted to the first transmission gear 24 is transmitted to the transmission shaft 25, the output gear 42 having a small diameter of the transmission shaft 25, and the large diameter. Through the third transmission gear 45, the transmission shaft 19, and the small-diameter fourth transmission gear 32, the transmission is sufficiently reduced and transmitted to the second transmission gear 30. In this case, when the transmission is performed from the small-diameter output gear 42 to the large-diameter third transmission gear 45 and when the transmission is performed twice from the small-diameter fourth transmission gear 32 to the second transmission gear 30, the normal transmission is performed. The rolling power is reduced. Further, since a transmission chain that requires a relatively large space as in the conventional structure is not used, restrictions from other parts are reduced, and the third transmission gear 45 is set to a large diameter gear. be able to. Since another cylindrical shaft or the like is not externally fitted to the end of the transmission shaft 25, when the output gear 42 is fixed to the end of the transmission shaft 25, the output gear 42 is connected to the outer diameter of the transmission shaft 25. The gear can be set to a sufficiently small diameter that is slightly larger than the gear.

With the above arrangement, when the left and right side gears are linked to the first transmission gear, the forward power transmitted to the first transmission gear is transmitted to the left and right traveling devices, and the left and right traveling devices are driven at the same speed. The aircraft moves straight ahead. Then, when the right or left side gear is separated from the first transmission gear and linked to the second transmission gear from the above-described state, the forward rotation power sufficiently reduced as described above is transmitted to the second transmission gear. Therefore, the right or left traveling device is driven forward at low speed by the decelerated forward power, and the aircraft turns right or left due to the difference in driving speed between the left and right traveling devices, and turns. is there.

For example, in the configuration shown in FIG. 1, the output gear 42 can be set to a sufficiently small diameter and the third transmission gear 45 can be set to a sufficiently large diameter.
There is a case where the forward rotation power can be sufficiently reduced only at the time of transmission to the third transmission gear 45 having a large diameter. In such a case, it is not necessary to make the second transmission gear 30 particularly large in diameter. Therefore, the diameter of the gear 28 that transmits power from the side gear 26 to the traveling device 27 can be reduced, and the position of the shaft of the gear 28 can be raised above the second transmission gear 30. Thereby, especially when the gear arrangement as shown in FIG. 1 is adopted, the bottom of the transmission case 1 (near the gear 28) can be raised to increase the minimum ground clearance of the work vehicle.

[0009]

As described above, when the forward rotation power decelerated for turning is transmitted to one traveling device, the forward rotation power sufficiently reduced without using a large space is transmitted to the one traveling device. You can now communicate. Thus, it is not necessary to make a structural change such as enlarging the outer transmission case and the like, which is advantageous in terms of structure. The difference between the driving speeds of the left and right traveling devices can be made sufficient between the other traveling device driven by the forward rotation power for straight traveling and the one traveling device driven by the reduced forward rotation power. Therefore, the steering and turning operations of the aircraft can be performed reliably even on particularly soft ground,
The steering and turning characteristics of the work vehicle were improved.

[0010]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a structure inside a transmission case 1 of a traveling system of a combine, which is one of the working vehicles, in which power from an engine (not shown) uses a belt transmission mechanism (not shown) provided with a tension clutch. The power is transmitted to the input pulley 3 of the belt-type continuously variable transmission 2 through the transmission. Power from the output shaft 4 of the belt-type continuously variable transmission 2 is cut via a first gear 5, a second gear 6, a first transmission shaft 7, a third gear 8, a fourth gear 9 and an output pulley 10 ( (Not shown).

A forward gear 11 and a reverse gear 12 are externally fitted to the first transmission shaft 7 so as to be relatively rotatable. A shift gear 13 is slidable between the forward and backward gears 11 and 12 by a spline structure. Is fitted outside. With this structure, when the shift gear 13 is engaged with the forward gear 11, the power of the first transmission shaft 7 is moved forward and the fifth gear 14
(Occlusion with the forward gear 11) to the second transmission shaft 15. When the shift gear 13 is engaged with the reverse gear 12, the power of the first transmission shaft 7 is moved in reverse and the reverse gear 12, the sixth gear pair 16, and the fifth gear 14 (the sixth gear pair 1).
6 and is transmitted to the 22nd transmission shaft 15.

A first high-speed gear 17 is fitted on the second transmission shaft 15 so as to be relatively rotatable, and a shift gear 18 is fitted with a spline structure so as to be slidable. A cylindrical shaft 39 is externally rotatably fitted to a third transmission shaft 19 disposed in the transmission case 1. The low-speed gear 20, the medium-speed gear 21, and the second high-speed gear 2
2 is fixed, and the first and second high-speed gears 17 and 22 are engaged. As a result, the shift gear 18 is slid and the first high-speed gear 17, the medium-speed gear 21 and the low-speed gear 20 are operated.
, The forward rotation power from the second transmission shaft 15 can be shifted to three stages of high, medium and low. This forward rotation power is transmitted from the linear gear 23 fixed to the cylindrical shaft 39 to the first rotation. The power is transmitted to the transmission gear 24.

Right and left side gears 26 are rotatably and slidably fitted on a fourth transmission shaft 25 (corresponding to a transmission shaft characteristic of the present invention) to which the first transmission gear 24 is fixed. And the input gears 28 of the left and right traveling devices 27
Are always engaged with the left and right side gears 26. Thus, by engaging the left and right side gears 26 with the first transmission gear 24 (corresponding to an interlocking connection position with the first transmission gear 24), the forward rotation power for straight traveling is transmitted to the left and right crawler type traveling device 27. I do. The spring 29 is connected to the side gear 26.
To the first transmission gear 24 side.

A pair of second transmission gears 30 are mounted on the left and right sides of the fourth transmission shaft 25 so as to be rotatable relative to each other, and a multi-plate friction clutch 31 is provided between the left and right second transmission gears 30 and the side gear 26.
Is provided. A small-diameter output gear 42 is fixed to the right end of the fourth transmission shaft 25 in the drawing, and a large-diameter third transmission gear 45 that is rotatably fitted to the third transmission shaft 19 is engaged with the output gear 42. ing. A shift member 44 is slidably fitted to the third transmission shaft 19 in a spline structure, and a switching lever 41 capable of slidably operating the shift member 44 is provided in a control section of the fuselage. A pair of small-diameter fourth transmission gears 32 are fixed to the left and right of the third transmission shaft 19, and the left and right fourth transmission gears 32 are engaged with the left and right second transmission gears 30.

With the above structure, as shown in FIG. 1, when the switching lever 41 is operated to the gentle turning position and the shift member 44 is slid to the left in the drawing, the shift member 44 meshes with the third transmission gear 45. Thereby, the first transmission gear 24
The forward rotation power for straight traveling transmitted to the fourth transmission shaft 25,
The power is converted into low-speed forward power via the output gear 42, the third transmission gear 45, the third transmission shaft 19, and the left and right fourth transmission gears 32, and transmitted to the left and right second transmission gears 30. Therefore,
For example, when the left side gear 26 is operated to be separated from the first transmission gear 24 and the friction clutch 31 is pressed and operated by the pressing portion 43 of the left side gear 26 (corresponding to an interlocking connection position with the second transmission gear 30), The low-speed forward power of the second transmission gear 30 is transmitted to the left traveling device 27, and the aircraft slowly turns left due to the speed difference between the left and right traveling devices 27.

Next, when the switching lever 41 is operated to the pivot position and the shift member 44 is slid rightward on the paper, the shift member 44 separates from the third transmission gear 45 and a convex portion on the inner surface of the transmission case 1. Bite 1a. Thus, the left and right second transmission gears 30 are stopped and held by the third transmission gear 19 and the left and right fourth transmission gears 32. Thereby, for example, the left side gear 26 is connected to the first transmission gear 24.
When the friction clutch 31 is pressed and operated by the pressing portion 43 of the left side gear 26, the left traveling device 2
The brake is applied to 7, and the aircraft turns to the left.

Next, the sliding operation structure of the left and right side gears 26 will be described. As shown in FIGS. 2 and 1, an operation arm 38 for sliding the left and right side gears 26 is provided.
And a hydraulic cylinder 33 for swinging the hydraulic cylinder. In this case, the hydraulic cylinder 33 is provided with a spring (not shown) for urging the hydraulic cylinder 33 toward the contraction side.
4 is supplied to an electromagnetically operated control valve 35 for a hydraulic cylinder 33. And the side gear 2
6 is separated from the first transmission gear 24 and the friction clutch 3
When the hydraulic cylinder 33 is extended until it moves to a neutral stop position where no 1 is pressed and operated, a drain oil passage 36 is provided to remove hydraulic oil from the hydraulic cylinder 33 and stop the hydraulic cylinder 33 at the neutral stop position. A variable relief valve 37 is provided in the drain oil passage 36.

Next, the control valve 35 and the variable relief valve 37
The operation of is described. The state shown in FIG. 2 and FIG.
The left and right side gears 26 are in a straight running state in which the first transmission gears 24 are engaged. In this state, for example, when the operation lever 40 is operated to the left first turning position L1, only the control valve 35 is switched to supply the hydraulic oil to the left hydraulic cylinder 33, and the left side gear 26 slides to the left on the paper. First
Move away from the transmission gear 24. In this case, the variable relief valve 3
7 is fully opened, the drain oil passage 36 is opened at the neutral stop position before the left side gear 26 presses the friction clutch 31, and the hydraulic oil flows out of the variable relief valve 37, so that the left side gear 26 is in the neutral position. Stop at the stop position. This is a state in which the transmission to the left traveling device 27 is cut off, and the aircraft gradually turns left.

When the operating lever 40 is operated to the left second turning position L2, the variable relief valve 37 is throttled, the hydraulic cylinder 33 is extended from the neutral stop position, and the left friction clutch 31 is engaged. Is done. in this case,
As shown in FIG. 1, if the switching lever 41 is operated to the gentle turning position and the shift member 44 is engaged with the third transmission gear 45, the left traveling device 27 is driven forward at a low speed to perform a gentle turning. . Further, the left first turning position L1 and the second turning position L2
When the operating lever 40 is operated between the above state, the operating oil is released from the hydraulic cylinder 33 from the above-described state, and the friction clutch 3
The pressing force to 1 is reduced. Thereby, the friction clutch 31 slips and the forward rotation speed of the left traveling device 27 can be changed.

Conversely, the switching lever 41 is operated to the pivot position to shift the shift member 44 to the convex portion 1 of the transmission case 1.
If the third transmission shaft 19 and the fourth transmission gear 32 are stopped and held by being engaged with the a, the left traveling device 27 is braked when the operation lever 40 is operated to the left second turning position L2. You can make a pivot. Also, the operation lever 40 is moved to the left first position.
When it is located between the second turning position L1 and the second turning position L2, the friction clutch 31 slips and the braking force on the left traveling device 27 can be changed as described above. The above operation is similarly performed at the right first turning position R1 and the second turning position R2.

[Alternative Embodiment] In the embodiment of FIG. 1, the side gear 26 and the first transmission gear 24 have an occlusion structure, and the friction clutch 31 is provided between the side gear 26 and the second transmission gear 30. A friction clutch is provided between the first transmission gear 24 and the side gear 26 and the second transmission gear 3.
0 may be configured as an occlusal structure, both may be configured as an occlusal structure, or both may be provided with a friction clutch.

Incidentally, reference numerals are written in the claims for convenience of comparison with the drawings, but the present invention is not limited to the configuration of the attached drawings by the entry.

[Brief description of the drawings]

FIG. 1 is a schematic view showing a transmission structure in a transmission case.

FIG. 2 is a hydraulic circuit diagram for sliding operation of left and right side gears.

[Explanation of symbols]

 Reference Signs List 19 transmission shaft 24 first transmission gear 25 transmission shaft fixedly supporting first transmission gear 26 side gear 27 traveling device 30 second transmission gear 32 fourth transmission gear 42 output gear

Claims (1)

(57) [Claims] 1. A first power transmission device for transmitting a forward rotation power for straight traveling.
A second transmission gear (30) is rotatably fitted to a transmission shaft (25) that fixedly supports the transmission gear (24), and a pair of left and right transmitting power to each of the pair of left and right traveling devices (27). The transmission shaft (25) is slidably movable relative to the side gear (26) between an interlocking connection position with the first transmission gear (24) and an interlocking connection position with the second transmission gear (30). ) And the transmission shaft (2)
5) a small-diameter output gear (42) fixed to the end portion, and a large-diameter third transmission gear (4) meshing with the output gear (42).
5) a transmission shaft (1) supporting the third transmission gear (45);
9) A small-diameter fourth transmission gear (32) for transmitting the power of the transmission shaft (19) to the second transmission gear (30) is provided, and forward rotation transmitted to the first transmission gear (24). The second transmission gear (30) converts the power into a reduced forward rotation power.
A traveling power transmission structure of a working vehicle configured to transmit power to a work vehicle.