JP4144155B2 - Front wheel transmission for work vehicle - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a front wheel transmission for a work vehicle, and more particularly to a front wheel transmission for a work vehicle such as an agricultural tractor or a riding management machine.
[0002]
[Prior art and problems to be solved by the invention]
2. Description of the Related Art Conventionally, work vehicles such as small tractors and passenger management machines are arranged with a power transmission shaft between a clutch housing and a transmission case provided at the rear of the clutch housing to transfer the rotational power of the engine to the transmission in the transmission case. Communicating. Further, the rotational power decelerated by the transmission is formed so as to be transmitted to the front wheels in front of the transmission case via the front wheel transmission.
[0003]
Thus, many of the front wheel transmissions are a combination of a wet multi-plate clutch and a transmission gear. Switching between the constant-speed four-wheel drive and the front-wheel speed-up four-wheel drive by switching the wet multi-plate clutch to the front wheels. introduce. However, the wet multi-plate clutch is expensive, and the wet multi-plate clutch and the transmission gear are combined, so there is a limit to downsizing. Furthermore, if the switching between the constant speed 4WD and the front wheel speed increasing 4WD is manually performed, the operation is complicated and an operation delay is likely to occur.
[0004]
Therefore, there is a technical problem to be solved in order to improve the operability by automating the switching operation and making the front wheel transmission of the work vehicle inexpensive and compact, and the present invention solves this problem. The purpose is to do.
[0005]
[Means for Solving the Problems]
The present invention has been proposed to achieve the above object, and the invention according to claim 1 is provided between the clutch housing (13) and a transmission case (14) provided behind the clutch housing (13). A power transmission shaft (15) is arranged on the front side to transmit the rotational power of the engine (12) to the transmission in the transmission case (14), and the rotational power reduced by the transmission is transmitted to the front wheel transmission (40). A transmission vehicle to the front wheel (20) in front of the transmission case (14), wherein the front wheel transmission (40) is configured in a gear case (18) attached to the front surface of the transmission case (14). Between the input shaft (41) and the output shaft (47) for the gear case (18), the rotational power transmitted to the front wheels (20) is transmitted at "constant speed" or "acceleration". A set of constantly meshing gears is provided, a slide key (46) biased toward the outer periphery of the input shaft (41) is provided in the input shaft (41), and an engaging portion of the slide key (46) Is engaged with the engaged portion provided at the pivotally attached portion of the constantly meshing gear, whereby the rotational power of the input shaft (41) is output through one of the constantly meshing gears. In a transmission device for a work vehicle configured by a key shift type transmission mechanism that transmits to a shaft (47),
A shifter (55), which is a speed change operation unit, is provided at the front part of the gear case (18) so as to be able to rotate back and forth, and the input shaft (41) for sliding the slide key (46) on the lower end of the shifter (55). ) Connect the front end of the shifter operating shaft (45) inserted inside,
The steering rod (64) connected to the pitman arm (60) through the steering gear device (24) provided at the lower end of the steering shaft (23) that rotates integrally with the steering handle (22) is operated. The drag arm boss (61) pivotally mounted in the lower left and right direction of the clutch housing (13) is connected to the tip of a drag arm (62) fixed to the vehicle body center side, while the drag arm boss (61 The arm boss (66) is pivotally mounted in the left-right direction at the lower position of the boss), and the arm (67) protrudes upward on the vehicle body center side of the arm boss (66), and on the vehicle body side of the arm boss (66). The arm (68) protrudes rearward, and a detent recess (70a) is provided on the lower surface of the drag arm boss (61) on the vehicle body side. An arc-shaped cam (70) provided at the center is fixed, and a boss (71) provided at the tip of the arm (68) is brought into contact with the circumferential surface of the cam (70), while the drag arm is provided. The boss (61) has a drag arm (63) fixed on the side of the vehicle body, and a drag rod (65) is forwardly connected to the tip of the drag arm (63) to connect to the knuckle arm.
Further, the upper end of the shifter (55) and the tip of the arm (67) are connected by a rod (72), and the slide key (46) is "increased" in conjunction with the operation of the steering handle (22). The gear case (18) is detachably attached to the front surface of the transmission case (14), and is connected to the front wheel transmission (40) from the transmission case (14). A reduction gear is provided between a rear wheel transmission shaft (28), which is a shaft for taking out power, and an input shaft (41) of the front wheel transmission (40). At this time, the front wheel is transmitted from the transmission case (14). A large-diameter gear (53) is fixed to a reduction gear shaft (52) pivotally mounted between the rear wheel transmission shaft (28) and the input shaft (41) for extracting power to the transmission (40). Set the gear (53) meshes the output gear (49) with the front end portion of the rear wheel transmission shaft (28) projecting forward from the transmission case (14), and the reduction gear shaft (52) has a small diameter gear ( 54), and the gear (54) is meshed with the input gear (48) fixed to the rear end of the input shaft (41).
In the invention according to claim 2 , power transmission is cut off between two sets of constantly meshing gears that transmit the rotational power of the input shaft (41) at "constant speed" or "acceleration". The front wheel transmission apparatus for a work vehicle according to claim 1, wherein a neutral portion is provided .
[0006]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. In the figure, reference numeral 10 denotes a small tractor as an example of a work vehicle. An engine 12 is mounted on a front portion of a vehicle body 11, and a clutch housing 13 is attached to a rear portion thereof. A transmission case 14 is fixed to the rear lower portion of the vehicle body 11, and a power transmission shaft 15 is disposed between the clutch housing 13 and the transmission case 14 to transmit the rotational power of the engine 12 to the transmission case 14.
[0007]
As will be described later, the power shifted by the transmission in the transmission case 14 is transmitted to the rear wheel 16 and also to the PTO take-out shaft 17 protruding rearward of the transmission case 14. A gear case 18 is attached to the front surface of the transmission case 14, and the power input to the transmission case 14 is shifted by a transmission within the gear case 18 and transmitted from the front wheel transmission shaft 19 to the front wheel 20. A transmission case 21 made of a substantially U-shaped sheet metal having an open bottom surface is installed between the clutch housing 13 and the transmission case 14, and the transmission case 21, the gear case 18, the front wheels are installed in the transmission case 21. Cover the transmission shaft 19 and the like. A steering handle 22 is a steering operation unit, and a steering gear device 24 is provided at the lower end portion of the steering shaft 23 that rotates integrally with the steering handle 22.
[0008]
The rotational power of the engine 12 is transmitted from the power transmission shaft 15 to the input shaft 26 in the transmission case 14 via the main clutch 25 provided in the clutch housing 13. A transmission shaft 27 is pivotally attached to the rear portion of the input shaft 26 so as to be coaxial with the input shaft 26, and a rear wheel transmission shaft is disposed below the input shaft 26 in parallel with the input shaft 26 and the transmission shaft 27. 28, a PTO transmission shaft 29 and a counter shaft 30 are pivotally attached. The power input to the input shaft 26 is transmitted to the cylindrical gear 33 that idles on the rear wheel transmission shaft 28 through the meshing of the gears 31 and 32, and is shifted by the main transmission 34 and the auxiliary transmission 35. Is transmitted from the rear wheel transmission shaft 28 to the rear wheels 16 and 16 via the rear differential device 36, and after being shifted by the PTO transmission device 37 from the cylindrical gear 33, the PTO transmission shaft 29 is moved to the PTO. It is transmitted to the take-out shaft 17.
[0009]
Here, a front wheel transmission device 40 is provided inside the gear case 18, and a constant speed four-wheel drive gear 42 and a front wheel speed-up four-wheel drive gear 43 are pivoted freely on an input shaft 41 of the front wheel transmission device 40. A plurality of locking grooves 44, 44... That are recessed in the radial direction are provided at the pivot portions of these gears 42, 43, and an engaged portion to which a tip of a slide key 46 described later is engaged is provided. Is formed. Further, an input gear 48 is fixed to the rear end portion of the input shaft 41 and meshed with an output gear 49 provided at the front end portion of the rear wheel transmission shaft 28 so that the rotational power of the rear wheel transmission shaft 28 is changed to the front wheel speed change. It is configured to be taken into the device 40. On the other hand, a gear 50 having substantially the same diameter as that of the constant-speed four-wheel drive gear 42 is fixed to the output shaft 47 of the front-wheel transmission device 40 so as to be always meshed with the constant-speed four-wheel drive gear 42 and the front wheel speed-up four-wheel drive gear. The front wheel transmission shaft 19 is connected to the front end of the output shaft 47.
[0010]
Inside the input shaft 41, a shifter operating shaft 45 made of a solid bar is slidably inserted in the front-rear direction, and the rear end portion of the shifter operating shaft 45 is cut into a slit shape to form two slides. Keys 46 and 46 are pivotally attached. A spring S is interposed between the tip portions of the pair of slide keys 46 and 46 so that the tip portions of the slide keys 46 and 46 are expanded toward the outer peripheral direction of the input shaft 41 by the spring S. When the shifter operating shaft 45 is slid back and forth and the slide keys 46 and 46 enter the locking groove 44 of either the constant speed four-wheel drive gear 42 or the front wheel speed-up four-wheel drive gear 43 when energized, the constant speed is reached. Either the four-wheel drive gear 42 or the front wheel speed-up four-wheel drive gear 43 rotates integrally with the input shaft 41, and the rotational power of the input shaft 41 is transmitted to the output shaft 47 at "constant speed" or "speed increase". A key shift type transmission mechanism is configured.
[0011]
Here, the front end portion of the rear wheel transmission shaft 28 protrudes forward of the transmission case 14, and an output gear 49 is provided at the protruding portion, and the input gear 48 is provided at the rear end portion of the input shaft 41 of the front wheel transmission 40. Is fixed. A reduction gear 52 is pivotally mounted between the transmission shaft 28 and the input shaft 41, which is a shaft for taking out power from the transmission case 14 to the front wheel transmission 40, and the reduction gear 52 has a large diameter. 53 is fixed and meshed with the output gear 49 , and a small-diameter gear 54 is fixed to the reduction gear 52 and meshed with the input gear 48 . That is, the rotational force of the rear wheel transmission shaft 28 is configured to be taken into the input shaft 41 of the front wheel transmission 40 after being decelerated by the gears 53 and 54 of the reduction gear shaft 52. Further, a shifter 55 that is a speed change operation unit is provided at a front portion in the gear case 18 so as to be able to turn back and forth, and the shifter 55 is connected to a front end portion of the shifter operation shaft 45.
[0012]
On the other hand, the steering gear device 24 is fixed to the upper portion of the clutch housing 13, and the pitman arm 60 is rotated by the rotation of the steering shaft 23. A drag arm boss 61 is pivotally attached to the lower side of the clutch housing 13 in the left-right direction, and a drag arm 62 is fixed to the vehicle body center side of the drag arm boss 61, and on the vehicle body side side of the drag arm boss 61. The drag arm 63 is fixed. Then, the distal end portion of one drag arm 62 and the distal end portion of the pitman arm 60 are connected by a steering rod 64, and the drag rod 65 is connected to the distal end portion of the other drag arm 63 to thereby knuckle arm (not shown). ). The steering gear device 24, the steering rod 64, the drag arm boss 61, the drag arms 62 and 63, the drag rod 65, and the like constitute a rotation member that interlocks with the rotation operation of the steering handle 22.
[0013]
Further, below the clutch housing 13, an arm boss 66 is pivotally attached to the lower position of the drag arm boss 61 in the left-right direction, and an arm 67 protrudes upward on the vehicle body center side of the arm boss 66. An arm 68 is projected rearward on the side of the vehicle body. An arc-shaped cam 70 is fixed to the lower surface of the drag arm boss 61 on the side of the vehicle body. The cam 70 is provided with a detent recess 70 a at the center of the arc, and a boss 71 (or roller) provided at the tip of the arm 68 is brought into contact with the circumferential surface of the cam 70. Further, the upper end of the shifter 55 and the tip of the arm 67 are connected by a rod 72.
[0014]
Thus, if the steering handle 22 is rotated, the pitman arm 60 of the steering gear device 24 rotates, and one drag arm 62 is pushed and pulled via the steering rod 64, and the drag arm boss 61 and the other The drag arm 63 rotates. Accordingly, the drag rod 65 is pushed and pulled, and the front wheels 20 and 20 that are steered wheels are turned to the left or right. Further, since the cam 70 rotates integrally with the drag arm boss 61, the boss 71 in contact with the cam 70 is pushed and moved from the detent recess 70a, and the arms 67, 68 and the arm boss 66 are integrated. The rod 72 is pushed and pulled, and the shifter 55 is rotated.
[0015]
Thus, the front wheels 20 and 20 are turned by the steering operation, the shifter operation shaft 45 of the front wheel transmission 40 is slid, and the tip of the slide keys 46 and 46 is locked to one of the gears 42 or 43. When entering the groove 44, the gear is shifted by the corresponding gear combination. That is, the switching operation of the front wheel transmission 40 can be automated in conjunction with the steering operation.
[0016]
For example, when the slide key 46 enters the locking groove 44 of the constant-speed four-wheel drive gear 42, the rotation of the input shaft 41 is caused by the meshing of the constant-speed four-wheel drive gear 42 and the gear 50 with the output shaft 47 to the front wheel transmission shaft. 19, the front wheel 20 is rotationally driven at a substantially constant peripheral speed with the rear wheel 16. On the other hand, when the slide key 46 enters the locking groove 44 of the front wheel speed increasing four-wheel drive gear 43, the rotation of the input shaft 41 is engaged with the front wheel speed increasing four wheel driving gear 43 and the gear 51 from the output shaft 47 to the front wheel. Transmitted to the transmission shaft 19, the front wheel 20 is rotationally driven at a circumferential speed approximately twice that of the rear wheel 16. That is, when the tractor 10 goes straight, the four-wheel drive travels at a constant speed by the combination of the gears 42, 50, and when the tractor 10 turns, the front wheel speed increases by the combination of the gears 43, 51. Is turned slightly. When the output gear 49 provided at the front end portion of the rear wheel transmission shaft 28 is slid by a shifter (not shown) to disengage the input gear 48, the rotational power of the rear wheel transmission shaft 28 is changed to the front wheel. It is not transmitted to the transmission 40 and the front wheels 20 are not driven. That is, the tractor 10 is a two-wheel drive running with only the rear wheels 16 and 16.
[0017]
Thus, since the front wheel transmission device 40 is configured by a key shift type transmission mechanism, it is less expensive and can be configured more compactly than a configuration in which a conventional wet multi-plate clutch is combined. In addition, since the shifter 55 that is the speed change operation unit is provided in the front part of the shifter operation shaft 45, the space between the clutch housing 13 and the transmission case 14 can be used effectively. Since the front wheel transmission shaft 19 is disposed below the shifter operation shaft 45, the shaft position on the transmission case 14 side and the shaft position on the front wheel 20 side can be made to coincide with each other at the same height. The power can be transmitted by shaft drive without using the like. Furthermore, since the link mechanism such as the steering operation arm and rod is housed inside the transmission case 21, it can be compactly constructed in the current space.
[0018]
The present invention can be variously modified without departing from the spirit of the present invention, and the present invention naturally extends to the modified one.
[0019]
【The invention's effect】
As described in detail in the above embodiment, the present invention can be formed compactly and inexpensively because the front wheel transmission that is detachably provided on the front surface of the transmission case is constituted by a key shift type transmission mechanism. Further, the front wheel transmission can be automatically switched in conjunction with the shift operation for sliding the shifter operation shaft of the speed change mechanism and the rotation operation of the steering handle, so that no operation delay occurs.
A shifter, which is a shift operation unit, is provided at the front part of the gear case so as to be able to rotate back and forth, and the front end of the shifter operation shaft inserted into the input shaft is connected to the lower end of the shifter to slide the slide key. As a result, the space between the clutch housing and the transmission case can be used effectively.
Furthermore, since the link mechanism such as the arm and rod of the steering operation system is located below the clutch housing, it can be easily housed in the transmission case and can be configured compactly in the current space.
In addition, a large-diameter gear is fixed to a reduction gear shaft pivotally mounted between the rear wheel transmission shaft and the input shaft for extracting power from the transmission case to the front wheel transmission, A front wheel end of the rear wheel transmission shaft meshes with an output gear formed to project forward from the transmission case, and a small-diameter gear is fixed to the reduction gear shaft, and the gear is fixed to the rear end of the input shaft. Therefore, the rotational power of the rear wheel transmission shaft is surely decelerated by the large diameter gear and the small diameter gear of the reduction gear shaft and then taken into the input shaft of the front wheel transmission.
[0020]
In the invention according to claim 2, since the gear case housing the front wheel transmission can be retrofitted to the transmission case, in addition to the effect of the invention according to claim 1, the front wheel transmission according to the specifications of the work vehicle is provided. Additional equipment can be easily installed. In addition, since the power taken in from the transmission case is input to the front wheel transmission after being decelerated by the reduction gear, the shaft rotation at the time of shifting is reduced and the switching shock is small. In addition, since the front wheel transmission is positioned higher than the front wheel shaft position, the link mechanism can be protected without lowering the minimum ground clearance of the vehicle body.
[0021]
The invention according to claim 3 provides the effect of the invention according to claim 1 or 2 by providing a neutral portion between two sets of gears that transmit at "constant speed" or "acceleration" of the front wheel transmission. In addition, since the power transmission is temporarily cut off during switching between “constant speed” and “acceleration”, the shift shock is reduced and the operability and durability can be improved.
[Brief description of the drawings]
The figure shows an embodiment of the present invention.
FIG. 1 is a side view of a small tractor.
FIG. 2 is a side view showing the inside of a transmission system such as a clutch housing and a transmission case.
FIG. 3 is a front view of FIG. 2;
FIG. 4 is an enlarged sectional view of a transmission case and a gear case.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 Tractor 12 Engine 13 Clutch housing 14 Transmission case 15 Power transmission shaft 18 Gear case 19 Front wheel transmission shaft 20 Front wheel 21 Transmission case 22 Steering handle 24 Steering gear device 28 Rear wheel transmission shaft 40 Front wheel transmission device 41 Input shaft 42 Constant speed 4WD Gear 43 Front-wheel speed-up four-wheel drive gear 44 Locking groove 45 Shifter operation shaft 46 Slide key 52 Reduction gear shaft 55 Shifter 61 Drag arm boss 62, 63 Drag arm 64 Steering rod 65 Drag rod

Claims (2)

A power transmission shaft (15) is arranged between the clutch housing (13) and a transmission case (14) provided at the rear of the clutch housing (13) to transmit the rotational power of the engine (12) in the transmission case (14). A transmission vehicle that transmits the rotational power decelerated by the transmission to the front wheels (20) in front of the transmission case (14) via the front wheel transmission (40). In constructing the device (40) in a gear case (18) attached to the front surface of the transmission case (14), a front wheel (20) is provided between the input shaft (41) and the output shaft (47) for the gear case (18). ) Are provided with two sets of constantly meshing gears that transmit the rotational power transmitted to the constant speed or increased speed, and the input shaft (41) has an outer periphery on the input shaft (41). By providing a slide key (46) biased in the direction, and engaging the engaging portion of the slide key (46) with the engaged portion provided in the pivoting portion of the constantly meshing gear, In a transmission for a work vehicle that includes a key shift type transmission mechanism that transmits the rotational power of the input shaft (41) to the output shaft (47) via one of the constantly meshing gears,
A shifter (55), which is a speed change operation unit, is provided at the front part of the gear case (18) so as to be able to rotate back and forth, and the input shaft (41) for sliding the slide key (46) on the lower end of the shifter (55). ) Connect the front end of the shifter operating shaft (45) inserted inside,
The steering rod (64) connected to the pitman arm (60) through the steering gear device (24) provided at the lower end of the steering shaft (23) that rotates integrally with the steering handle (22) is operated. The drag arm boss (61) pivotally mounted in the lower left and right direction of the clutch housing (13) is connected to the tip of a drag arm (62) fixed to the vehicle body center side, while the drag arm boss (61 The arm boss (66) is pivotally mounted in the left-right direction at the lower position of the boss), and the arm (67) protrudes upward on the vehicle body center side of the arm boss (66), and on the vehicle body side side of the arm boss (66). The arm (68) protrudes rearward, and a detent recess (70a) is provided on the lower surface of the drag arm boss (61) on the vehicle body side. An arc-shaped cam (70) provided at the center is fixed, and a boss (71) provided at the tip of the arm (68) is brought into contact with the circumferential surface of the cam (70), while the drag arm is provided. The boss (61) has a drag arm (63) fixed on the side of the vehicle body, and a drag rod (65) is forwardly connected to the tip of the drag arm (63) to connect to the knuckle arm.
Further, the upper end of the shifter (55) and the tip of the arm (67) are connected by a rod (72), and the slide key (46) is "increased" in conjunction with the operation of the steering handle (22). The gear case (18) is detachably attached to the front surface of the transmission case (14), and is connected to the front wheel transmission (40) from the transmission case (14). A reduction gear is provided between a rear wheel transmission shaft (28), which is a shaft for taking out power, and an input shaft (41) of the front wheel transmission (40). At this time, the front wheel is transmitted from the transmission case (14). A large-diameter gear (53) is fixed to a reduction gear shaft (52) pivotally mounted between the rear wheel transmission shaft (28) and the input shaft (41) for extracting power to the transmission (40). Set the gear (53) meshes the output gear (49) with the front end portion of the rear wheel transmission shaft (28) projecting forward from the transmission case (14), and the reduction gear shaft (52) has a small diameter gear ( 54), and the gear (54) is engaged with the input gear (48) fixed to the rear end of the input shaft (41). The neutral part which cuts power transmission is provided between two sets of always-meshing type gears which transmit rotational power of the input shaft (41) at "constant speed" or "acceleration" . Front wheel transmission for work vehicle.

Images