PADDY FIELD WORK MACHINE

BACKGROUND OF THE INVENTION

1. Technical Field of the Invention

The invention is directed to a paddy field work machine comprising: a riding type driving section; a main change speed device configured to change in speed of a driving force from an engine; and a transmission case configured to receive the driving force from the main change speed device for outputting the inputted driving force to a propelling device and an implement work section.

2. Description of the Related Art

Such a conventional paddy field work machine is disclosed in e.g. JP 2009-092169 A which describes a riding type rice seedling planting machine - one example of the paddy field work machine.

Such a riding type rice seedling planting machine includes: a gear type auxiliary change speed mechanism; and a gear type, planting pitch providing change speed device, with each being housed within a case acting as a transmission case. The driving force inputted from the main change speed device into the case is divided into a propelling device oriented force and a work implement oriented force. The divided, propelling device oriented force is inputted into the gear type auxiliary change speed mechanism and changed in speed, and outputted therefrom to front wheels and rear wheels. On the other hand, the work implement oriented force is inputted into the gear type, planting pitch providing change speed device and changed in speed, and outputted therefrom to a seedling planting device.

In the paddy field work machine, it is of advantage if the propelling device can be driven with a greater driving force than the force when the work machine is propelled while driving the work implement, and the force when the work machine is moved to/from the field. Th is allows for smooth movement over a ridge in the field, as well as smooth escape from the muddy field when the propelling device is sunken into a deep muddy layer, so that the movement between the fields and the implement work on the field can be done quickly and easily.

With the conventional change speed and transmission technique as described above, if the propelling device is to be driven with a greater driving force than the force when the work machine is propelled while driving the work implement, and the force when the work machine is moved to/from the field, large number of speeds (speed stages) are required for a single, gear type auxiliary change speed mechanism. However, this results in increased size of the auxiliary change speed mechanism with large diameter gears, as well as increased vertical dimension of the transmission case.

In view of the foregoing, it is desired to provide a paddy field work machine which drives the propelling device sufficient to move between the ridges and to escape from the field while avoiding a size increase of the transmission case, and which provides the implement work section with a simple transmission structure for changing in speed in multiple speeds (speed stages).

SUMMARY OF THE INVENTION

One aspect of the paddy field work machine is as under :-

A paddy field work machine comprising:

a riding type driving section;

a main change speed device configured to change in speed of a driving force from an engine; and

a transmission case configured to receive the driving force from the main change speed device for outputting the inputted driving force to a propelling device and an implement work section;

characterized in that

the transmission case houses an auxiliary gearshift transmission, a work implement gearshift transmission and a propelling device auxiliary gearshift transmission;

the auxiliary gearshift transmission is configured to change in speed of the driving force from the main change speed device to one of a plurality of speeds, and to divide and output the driving force into a work implement oriented force and a propelling device oriented force;

the work implement gearshift transmission is configured to change in speed of the outputted work implement oriented force to one of a plurality of speeds, and to output the force to the implement work section; and

the propelling device auxiliary gearshift transmission is configured to change in speed of the outputted propelling device oriented force into one of a plurality of speeds, and to output the force to the propelling device.

According to the above aspect, the driving force from the main change speed device is inputted into the auxiliary gearshift transmission and changed in speed, and thereafter inputted into the propelling device auxiliary gearshift transmission and further changed in speed, and the resulting force is outputted to the propelling device. Therefore, compared with the structure in which the driving force from the main change speed device is changed in speed with one and only multiple stage, gearshift transmission and the resulting drive force is outputted therefrom, the driving force from the main change speed device can be changed into one of a multiple speeds (speed stages) and outputted to the propelling device, while restricting against diameter enlargement of the gears in each of the auxiliary gearshift transmission and the propelling device auxiliary gearshift transmission. That is, the driving force having a rotational speed appropriate for the movement between the fields and the implement work on the field can be generated and outputted to the propelling device; and further, the driving force having a rotational speed sufficient for smooth movement over a ridge in the field, as well as for escape from the muddy field, can be generated and outputted to the propelling device.

According to the above aspect, the driving force from the main change speed device is inputted into the auxiliary gearshift transmission and changed in speed, and thereafter inputted into the propelling device auxiliary gearshift transmission and further changed in speed. Therefore, while the auxiliary gearshift transmission has a simple structure as well as utility for a work implement oriented gearshift transmission, a multiple of the work implement oriented speeds (speed stages) can be provided by combining the number of speeds (speed stages) in the auxiliary gearshift transmission with the number of speeds (speed stages) in the work implement gearshift transmission, for outputting the resulting driving force to the implement work section in one of the multiple of work implement oriented speeds (speed stages).

Thus, when the work machine is to move between the fields or when the propelling device is sunken into a deep muddy layer, the propelling device is driven with a driving force sufficient to move over a ridge in the field, as well as escaping from the muddy field, so that the movement between the fields and the escape from the muddy field can be done quickly and easily. Besides, this provides another advantage resulting from smaller gear diameter of the gears in each of the gearshift transmissions for making the transmission case compact with a smaller height from the ground. In addition, the implement work section can be configured to provide a multiple of the work implement oriented speeds (speed stages), with the auxiliary gearshift transmission having a simple structure, as well as utility for a work implement oriented gearshift transmission.

According to one preferred aspect of the invention, the riding type driving section includes: a driver's seat side operating section having a driver's seat, and a steering wheel side operating section having a steering wheel; and the steering wheel side operating section includes an auxiliary shift tool for shifting the auxiliary gearshift transmission.

According to the above aspect, even when the driver's hand is placed on the steering wheel, the hand can reach the auxiliary shift tool easily and quickly with only a slight movement of the hand from the steering wheel for operating auxiliary shift tool.

Compared with the propelling device auxiliary gearshift transmission, the auxiliary gearshift transmission is used more frequently to effect the change in speed, since typically the auxiliary gearshift transmission is operative for a switchover between when the work machine is propelled while driving the work implement and when it is

moved to/from the field; whereas the propelling device auxiliary gearshift transmission is operative when the work machine is moving over a ridge in the field and when it is escaping from the muddy field. According to the present aspect, the auxiliary gearshift transmission, operated more frequently, can be changed in speed with more ease and thus of more advantage.

According to another preferred aspect of the invention, the riding type driving section includes: a driver's seat side operating section having a driver's seat, and a steering wheel side operating section having a steering wheel; and the driver's seat side operating section includes a propelling device auxiliary shift tool for shifting the propelling device auxiliary gearshift transmission.

According to the above aspect, the propelling device auxiliary shift tool for changing in speed of the propelling device auxiliary gearshift transmission is arranged in the vicinity of the driver's seat, and so advantageously the propelling device auxiliary shift tool will not block the steering operation.

Compared with the auxiliary gearshift transmission, the propelling device auxiliary gearshift transmission is used less frequently to effect the change in speed, since typically the auxiliary gearshift transmission is operative for a switchover between when the work machine is propelled while driving the work implement and when it is moved to/from the field; whereas the propelling device auxiliary gearshift transmission is operative when the work machine is moving over a ridge in the field and escaping from the muddy field.

According to the present aspect, the propelling device auxiliary gearshift transmission, operated less frequently, is advantageously arranged at a position difficult to block the steering operation.

According to still another preferred aspect of the invention, the work implement gearshift
transmission includes: an input shaft; a pair of input gears supported on the input shaft to be rotatable in unison with and slidable relative to the input shaft; and a gearshift transmission section; wherein, when one of the pair of input gears is engaged with a pair of change speed gears of the gearshift transmission section, the work implement gearshift transmission is configured to change in speed of the driving force of the pair of change speed gears to one of a plurality of speeds and transmitting the driving force to an output shaft.

According to the above aspect, the work implement gearshift transmission may have a predetermined number of a multiple gearshift speeds (speed stages) by combining the number of speeds (speed stages), which is produced by a mesh between the pair of input gears and the pair of change speed gears in the gearshift transmission section engaged therewith, with the number of speeds (speed stages) in the gearshift transmission section.

That is, compared with the work implement gearshift transmission having one and only input gear for providing the work implement gearshift transmission with a predetermined number of a multiple of speeds (speed stages), the present aspect reduces the number of gears in the gearshift transmission section for providing the work implement gearshift transmission with the predetermined number of a multiple gearshift speeds (speed stages).

Thus, the work implement gearshift transmission can be downsized with smaller number of gears in the gearshift transmission section, while driving the implement work section at one of the multiple gearshift speeds (speed stages).

According to still yet another preferred aspect of the invention, the gearshift transmission section includes: an intermediate transmission shaft supporting the pair of change speed gears to be rotatable in unison therewith; the output shaft; and a gear pair extending between the output shaft and a portion of the intermediate transmission shaft extending between the pair of change speed gears for changing in speed of the driving force of the intermediate transmission shaft and outputting the driving force to the output shaft.

According to the above aspect, a greater difference can be provided between (i) a gearshift ratio between one of the pair of the input gears and the change speed gear in the gearshift transmission section meshed therewith and (ii) a gearshift ratio between the other of the pair of the input gears and the change speed gear in the gearshift transmission section meshed therewith, whereby the work implement gearshift transmission as a whole may have a larger variety of gearshift speeds (speed stages).

Thus, the implement work section may be driven with a larger variety of gearshift speeds.

If the subject work machine is a paddy field rice seedling planting machine, it can advantageously perform a seedling planting operation while adjusting a planting pitch with a larger variation in the propelling direction.

Other aspects of the invention, as well as advantageous effects derived from the same, will be apparent by reading the detailed description as follows with reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings:-

Fig. 1 is a side view showing an entire paddy field work machine;

Fig. 2 is a plan view showing the entire paddy field work machine;

Fig. 3 is a diagram showing a driving force transmission apparatus;

Fig. 4 is a diagram showing a portion of the transmission apparatus corresponding to a
work implement driving force transmission;
Fig. 5 is a developed view in section showing an auxiliary gearshift transmission, a propelling device auxiliary gearshift transmission and a front wheel differential mechanism;

Fig. 6 is view in section showing the work implement gearshift transmission; and;

Fig. 7 is a side view in vertical section showing a portion of a transmission case housing the auxiliary gearshift transmission, the propelling device auxiliary gearshift transmission and the front wheel differential mechanism.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT (S)

An embodiment of the invention will be described hereinafter with reference to the accompanying drawings.

Fig. 1 is a side view showing an entire paddy field work machine according to an embodiment of the invention. Fig. 2 is a plan view showing the entire paddy field work machine according to the same embodiment. As shown in Figs. 1 and 2, the paddy field work machine (exemplified herein as a paddy field rice seedling planting machine) according to the embodiment includes: a the self-propelling vehicle configured to run by itself via a pair of, right and left, steering and driving front wheels (each forms an example of a propelling device) 1, 1 and a pair of, right and left, driving rear wheels (each forms an example of a propelling device) 2, 2; an implement work section 4 connected to a rear portion of a vehicle body frame 3 of the self-propelling vehicle via a link mechanism 6 to be raised and lowered relative to the ground; and a fertilizer feeding device 7 disposed at a rearward position of the self-propelling vehicle.

The paddy field work machine is configured to swing the link mechanism 6 by a hydraulic cylinder 5 to lower the implement work section 4 to a lowered state where ground engaging floats 23 come into contact with the ground in a field. In this state, the self-propelling vehicle is propelled to perform a six-row seedling planting work by the implement work section 4; and a fertilizer feeding work in which the fertilizer is supplied to the field by the fertilizer feeding device 7 adjacent to lateral sides of the six-row planted seedlings.

The self-propelling vehicle will be described next in more detail.

As shown in Figs. 1 and 2, the self-propelling vehicle includes a riding type driving section having a driver's seat 11 disposed at a rearward position of the vehicle body. The riding type driving section 10 includes: a driving section (an example of a driver's seat side operating section) 10 A h aving a driver's seat 11 and a control panel 12 disposed on each of right and left sides of the driver's seat 11; and a steering section (an example of a steering wheel side operating section) 1 OB having a steering wheel 15 provided forwardly of the driver's seat 11 and a driver's control panel 16 provided downwardly of the steering wheel 15.

The self-propelling vehicle includes an engine 30 mounted at a forward position of the vehicle body frame 3. A driving force (or power) from the engine 30 is transmitted to right and left front wheel driving cases 31 and a rear wheel driving case 32 for driving the pair of right and left front wheels 1, 1 and the pair of right and left rear wheels 2, 2, respectively.

The implement work section 4 will be described next in more detail.

As shown in Figs. 1 and 2, the implement work section 4 includes a planting body frame 25 having its forward end connected to a rear end of the link mechanism 6. The planting body frame 25 includes: a feeding case 26 connected to a rear end of the link mechanism 6; and three (3) planting power feeding cases 27 arranged in a right/left direction relative to the self-propelling vehicle body at a predetermined distance from one another.

The implement work section 4 includes: six (6) seedling planting mechanisms 22 arranged in the right/left direction relative to the self-propelling vehicle body, with each being drivingly supported at a rear end on a right/left side of the planting power feeding case 27 associated therewith; a seedling mount 21 provided upwardly of the planting body frame 25 with a rearward inclination toward a lower end thereof; and three (3) ground engaging floats 23 arranged downwardly of the planting body frame 25, side by side in the right/left direction relative to the self-propelling vehicle body.

The implement work section 4 is configured to drive the seedling planting mechanisms 22, the seedling mount 21 and seedling vertically feeding belts 24 extending along six (6) rows of seedling mounting sections in the seedling mount 21.

In particular, the driving force from the engine 30 is inputted into the feeding case 26 for dividing it into a planting force and a seedling feeding force. The divided, planting force is transmitted to the planting power feeding case 27 for driving the seedling planting mechanism 22. On the other hand, the divided, seedling feeding force is transmitted to a seedling mount transversely feeding mechanism (not shown). In response thereto, the seedling mount 21 is transversely reciprocated in association with a seedling planting movement of the seedling planting mechanism 22. Also, the divided, seedling feeding force is transmitted to a seedling mount vertically feeding mechanism (not shown). In response thereto, the seedling vertically feeding belts 24 are driven.

The fertilizer feeding device 7 will be described next in more detail.

The fertilizer feeding device 7 is configured to take out a granular fertilizer material stored in a fertilizer tank 18 in a predetermined amount by four (4) feeding devices 19 which are arranged under the fertilizer tank 18 side by side in the right/left direction relative to the self-propelling vehicle body and connected to one another. The fertilizer material taken out by each of the feeding devices 19 is supplied under the transporting wind from a transporting blower 28, to six (6) groove forming devices 29 which are provided in the implement work section 4 and connected to the feeding device 19 associated therewith via a fertilizer feeding hose 29a. Each of the six (6) groove forming device 29 is arranged on a right/left side of seedling planting mechanism 22 associated therewith in the right/left direction relative to the self-propelling vehicle body, and supported by the ground engaging float 23 associated therewith. Each of the groove forming devices 29 forms a fertilizer feeding groove on the field in a region adjacent to a right/left side of a seedling planting site by the seedling planting mechanism 22, and the fertilizer material is supplied to the fertilizer feeding groove via the fertilizer feeding hose 29a.

A driving force transmission apparatus (referred to also as "transmission apparatus" hereinafter) A for driving the right and left front wheels 1, 1, the right and left rear wheels 2, 2 and the implement work section 4 will be described next in more detail Fig. 3 is a diagram showing the transmission apparatus A. Fig. 4 is a diagram showing a portion of the transmission apparatus A corresponding to a work implement driving force transmission 60. Fig. 5 is a developed view in section showing an auxiliary gearshift transmission 40, a propelling device auxiliary gearshift transmission 50 and a front wheel differential mechanism 70.

As shown in Figs. 1-5, the transmission apparatus A includes: a transmission case 35 supported by the right and left front wheels 1,1; and a main change speed device 36 supported on a lateral end portion of the transmission case 35. The transmission apparatus

A further includes: the auxiliary gearshift transmission 40, the propelling device auxiliary gearshift transmission 50, the work implement gearshift transmission 60 and the front wheel differential mechanism 70, each housed within the transmission case 35.

The main change speed device 36 includes an axial plunger type, variable displacement hydraulic pump 36P and an axial plunder type hydraulic motor 36M driven by pressurized oil from the hydraulic pump 36P, to thereby form a hydrostatic stepless transmission (HST). The main change speed device 36 is configured to effect a change speed operation by a main shift lever 37 (an example of a main shift tool) which is provided in the driving section 10A. In the driving section 10A, the main shift lever 37 is arranged on one of the control panels 12 provided on a right side of the driver's seat 11 to be pivotable in a fore/aft direction relative to the vehicle body.

In the transmission apparatus A, the driving force from an output shaft 30a of the engine 30 is inputted to a pump shaft 36a (acting as an input shaft of the hydraulic pump 36) via a belt transmission mechanism 39; and the driving force from a motor shaft 36b (acting as an output shaft of the main change speed device 36) is inputted into the transmission case 35. The driving force inputted into the transmission case 35 is in turn inputted to and changed in speed at the auxiliary gearshift transmission 40, and thereafter divided into, a propelling device oriented force and an implement work oriented force. The divided and outputted propelling device oriented force is inputted to and further changed in speed at the propelling device auxiliary gearshift transmission 50 and further divided into a front wheel oriented force and a rear wheel oriented force. The divided, front wheel oriented force is inputted to the front wheel differential mechanism 70 and goes out of the transmission case 35 through right and left outer sides thereof via a pair of right and left front wheel output shaft 71, 71 of the front wheel differential mechanism 70, toward a pair of right and left front wheel driving cases 31,31. The front wheel differential mechanism 70 is configured to effect a switchover between a differential allowed state (differential unlocked state) and a differential inhibited state (differential locked state) by a differential locking member 72 which is operable to come into engagement with and disengagement from a differential case. The right/left front wheel driving case 31 extends from the right/left side of the transmission case 35, laterally and outwardly relative to the vehicle body. The states of the differential locking member 72 are switched over by a rotatable control shaft 72a (Fig. 5).

In the transmission apparatus A, after the shifting operation by the propelling device auxiliary gearshift transmission 50, the divided and outputted rear wheel oriented force is transmitted to a rear wheel output shaft 35a supported at a rearward position of the transmission case 35, and then goes out through a rear side of the transmission case 35 along the rear wheel output shaft 35a to a rear wheel input shaft 32a of a rear wheel driving case 32. A rear wheel brake BR is mounted on the rear wheel output shaft 35a.

The rear wheel driving case 32 is supported at a rear end portion of the vehicle body frame 3. The rear wheel output shaft 35a is connected to the rear wheel input shaft 32a by a rotary transmission shaft 35b.

In the transmission apparatus A, after the shifting operation by the auxiliary gearshift transmission 40, the divided and outputted work implement oriented force is inputted to and changed in speed by the work implement gearshift transmission 60. Thereafter, the force is transmitted to a work implement oriented output shaft 35c supported at a rear portion of the transmission case 35, and then transmitted rearwardly of the transmission case 35 via the work implement oriented output shaft 35c to a work implement oriented input shaft 26a in the implement work section 4. The work implement oriented output shaft 35c has a work implement oriented clutch 61 mounted thereon, The work implement oriented output shaft 35c is connected to the work implement oriented input shaft 26a via a the rotary transmission shaft 35d provided on the self-propelling vehicle side and extending from the work implement oriented output shaft 35c to a rear end portion of the self-propelling vehicle, and via a rotary transmission shaft 26b provided on the implement work section side and extending from the rotary transmission shaft 35d to the work implement oriented input shaft 26a. The rotary transmission shaft 26b on the implement work section side is connected to the rotary transmission shaft 35d on the self-propelling vehicle side and to the work implement oriented input shaft 26a by respective universal joints.

The auxiliary gearshift transmission 40 will be described next in more detail.

As shown in Figs. 3 and 5, the auxiliary gearshift transmission 40 includes: an input shaft 41 acting as an input shaft of the transmission case 35; an output shaft 42 extending parallel to the input shaft 41; a pair of shift gears 43, 44 mounted on the input shaft 41 to be rotatable in unison with and slidable relative to the input shaft 41; and a pair of shift gears 45, 46 mounted on the output shaft 42 to be rotatable in unison with the output shaft 42. The input shaft 41 is connected to the motor shaft 36b of the main change speed device 36. The pair of shift gears 43, 44 are interconnected to be slidable in unison relative to the input shaft 41.

The auxiliary gearshift transmission 40 provides two, high and low, speeds (speed stages) by shifting the pair of shift gears 43, 44.

In particular, the auxiliary gearshift transmission 40 provides the low speed by meshing the smaller diameter shift gear 43 with one change speed gear 45, whereby the driving force is transmitted from the input shaft 41 via the shift gear 43 and the change speed gear 45 to the output shaft 42.

On the other hand, the auxiliary gearshift transmission 40 provides the high speed by meshing the larger diameter shift gear 44 with the other change speed gear 46, whereby the driving force is transmitted from the input shaft 41 via the shift gear 44 and the change speed gear 46 to the output shaft 42.

Regardless the auxiliary gearshift transmission 40 provides the high speed or the low speed, the driving force on the output shaft 42 is divided into the propelling device oriented force and the outputted work implement oriented force; and the divided and outputted propelling device oriented force is transmitted to the propelling device auxiliary gearshift transmission 50, whereas the divided and outputted work implement oriented force is transmitted to the work implement gearshift transmission 60.

In particular, the output shaft 42 has a propelling device oriented output gear 47 at one end thereof to be rotatable in unison therewith, and a work implement oriented output gear 48 at the other end thereof to be rotatable in unison therewith.

In operation of the auxiliary gearshift transmission 40, when the larger diameter shift gear 52 of the pair of shift gears 51, 52 of the propelling device auxiliary gearshift transmission 50 is meshed with the propelling device oriented output gear 47, the driving force on the output shaft 42 is divided by the propelling device oriented output gear 47 and the work implement oriented output gear 48 into the propelling device oriented force and the implement oriented force, respectively. The divided and outputted propelling device oriented force is transmitted from the propelling device oriented output gear 47 to the propelling device auxiliary gearshift transmission 50, whereas the divided and outputted work implement oriented force is transmitted from the work implement oriented output gear 48 to the work implement gearshift transmission 60.

In operation of the auxiliary gearshift transmission 40, when the smaller diameter shift gear 51 of the pair of shift gears 51, 52 in the propelling device auxiliary gearshift transmission 50 is meshed with the other change speed gear 46, the driving force on the output shaft 42 is divided by the other change speed gear 46 and the work implement oriented output gear 48 into the propelling device oriented force and the implement oriented force, respectively. The divided and outputted propelling device oriented force is transmitted from the other change speed gear 46 to the propelling device auxiliary gearshift transmission 50, whereas the divided and outputted work implement oriented force is transmitted from the work implement oriented output gear 48 to the work implement gearshift transmission 60.

The auxiliary gearshift transmission 40 is configured to change in speed by an auxiliary shift lever 49 which is provided in the steering section 10B for acting as an auxiliary shift tool. The auxiliary shift lever 49 is arranged in the steering section 10B at a portion on a left lower side of the steering wheel 15 adjacent a steering column, to be movable in the right/left direction relative to the self-propelling vehicle body.

The propelling device auxiliary gearshift transmission 50 will be described next in more detail.

The propelling device auxiliary gearshift transmission 50 includes the other change speed gear 46 and the propelling device oriented output gear 47 in the auxiliary gearshift transmission 40; an output shaft 53 extending parallel to the output shaft 42 in the auxiliary gearshift transmission 40; and a pair of shift gears 51, 52 mounted on the output shaft 53 to be rotatable in unison with and slidable relative to the output shaft 53. The pair of shift gears 51, 52 are interconnected to be slidable in unison with each other relative to the output shaft 53.

The propelling device auxiliary gearshift transmission 50 is configured to provide two, high and low, speeds by shifting the pair of shift gears 51, 52.

In particular, the propelling device auxiliary gearshift transmission 50 provides the low speed when the larger diameter shift gear 52 of the pair of shift gears 51, 52 is meshed with the output gear 47 in the auxiliary gearshift transmission 40, whereby the divided and outputted propelling device oriented force from the auxiliary gearshift transmission 40 is transmitted by the shift gear 52 to the output shaft 53.

On the other hand, the propelling device auxiliary gearshift transmission 50 provides the high speed when the smaller diameter shift gear 51 of the pair of shift gears 51, 52 is meshed with the other change speed gear 46 in the auxiliary gearshift transmission 40, whereby the divided and outputted propelling device oriented force from the auxiliary gearshift transmission 40 is transmitted by the shift gear 51 to the output shaft 53.

Regardless the propelling device auxiliary gearshift transmission 50 provides the high speed or the low speed, the driving force on the output shaft 53 is divided into the front wheel oriented force and the rear wheel oriented force by a front wheel output shaft 54 mounted at one end of the output shaft 53 to be rotatable in unison with the output shaft 53, and by a rear wheel output gear 55 mounted at the other end of the output shaft 53 to be rotatable in unison with the output shaft 53, respectively. The divided and outputted front wheel oriented force is transmitted to an input gear 73 to the front wheel differential mechanism 70, whereas the divided and outputted rear wheel oriented force is transmitted to a transmission gear 56 which is mounted on the rear wheel output shaft 35a to be rotatable in unison therewith.

The propelling device auxiliary gearshift transmission 50 is configured to change in speed by a propelling device auxiliary shift lever 57 which is provided in the driving section 10 A fo r acting as a propelling device auxiliary shift tool. The propelling device auxiliary shift lever 57 is arranged on one of the control panels 12 in the driving section 10 A which extends on a left side of the driver's seat 11, to be movable in the fore/aft direction relative to the vehicle body.

Thus, the transmission apparatus A provides one of four (4) auxiliary gearshift speeds (first to fourth auxiliary gearshift speeds) by shifting the auxiliary gearshift transmission 40 and the propelling device auxiliary gearshift transmission 50 in an appropriate manner.

In particular, when the transmission apparatus A is switched over to the fourth auxiliary gearshift speed, the driving force from the main change speed device 36 is subject to an auxiliary change speed operation to provide a rotational speed appropriate for propelling the vehicle, and the resultant force is transmitted to the front wheels 1 and the rear wheels 2.

When the transmission apparatus A is switched over to the third auxiliary gearshift speed, the driving force from the main change speed device 36 is subject to the auxiliary change speed operation to provide a rotational speed appropriate for driving the work implement and lower than the rotational speed at the fourth auxiliary gearshift speed, and the resultant force is transmitted to the front wheels 1 and the rear wheels 2.

When the transmission apparatus A is switched over to the second auxiliary gearshift speed, the driving force from the main change speed device 36 is subject to the auxiliary change speed operation to provide a rotational speed appropriate for driving over a ridge in the field and lower than the rotational speed at the third auxiliary gearshift speed, and the resultant force is transmitted to the front wheels 1 and the rear wheels 2.

When the transmission apparatus A is switched over to the first auxiliary gearshift speed, the driving force from the main change speed device 36 is subject to the auxiliary change speed operation to provide a rotational speed sufficient to escape from the muddy field and lower than the rotational speed at the second auxiliary gearshift speed, and the resultant force is transmitted to the front wheels 1 and the rear wheels 2.

The work implement gearshift transmission 60 will be described next in more detail.

As shown in Figs. 4 and 6, the work implement gearshift transmission 60 includes: an input shaft 62 which receives the driving force from the work implement oriented output gear 48 in the auxiliary gearshift transmission 40 via a torque limiter T; an intermediate transmission shaft 63 and an output shaft 64 each extending parallel to the input shaft 62; a pair of input gears 65, 66 mounted on the input shaft 62 to be rotatable in unison with and slidable relative to the input shaft 62; and the gearshift transmission section 80 extending from the intermediate transmission shaft 63 to the output shaft 64. The intermediate transmission shaft 63 is mounted on the input shaft 41 in the auxiliary gearshift transmission 40 to be rotatable relative to the input shaft 41.

The pair of the input gears 65, 66 are interconnected to be slidable in unison with each other relative to the input shaft 62. The larger input gear 65 of the pair of the input gears 65, 66 is operable to be engaged with and disengaged from a change speed gear 81 located on one outermost side among change speed gears 81-85 which are supported on and arranged axially side by side of the intermediate transmission shaft 63. The smaller input gear 66 of the pair of the input gears 65, 66 is operable to be engaged with and disengaged from the change speed gear 85 located on the other outermost side among the change speed gears 81-85.

The gearshift transmission section 80 includes the five (5) change speed gears 81-85 which are arranged axially of and mounted on the intermediate transmission shaft 63, and four (4) output gears 86-89 mounted on the output shaft 64.

Among the five (5) change speed gears 81-85 mounted on the intermediate transmission shaft 63, the four (4) gears 81-84, excluding the change speed gear 85 operable to be engaged with and disengaged from the smaller diameter input gear 66, are meshed with the four (4) output gears 86-89 mounted on the output shaft 64, respectively. Whereby, the four (4) gears 81-84 mounted on the intermediate transmission shaft 63 and the four (4) output gears 86-89 mounted on the output shaft 64 form gear pairs G1-G4 between the intermediate transmission shaft 63 and the output shaft 64. Three (3) gear pairs G2-G4 of the gear pairs G1-G4 are provided within a portion of the intermediate transmission shaft 63 extending between the change speed gear 81 to be engaged/disengaged with/from the larger diameter input gear 65 and the change speed gear 85 to be engaged/disengaged with/from the smaller input gear 66.

The five (5) change speed gears 81-85 are mounted on the intermediate transmission shaft 63 to be rotatable in unison with the intermediate transmission shaft 63. The four (4) output gears 86-89 is mounted on the output shaft 64 to be rotatable relative to the output shaft 64. On a cylindrical shaft portion of the output shaft 64 mounting the four (4) output gears 86-89, clutch balls 90 are supported to be revolvable in unison with the output shaft 64 and operable to be engaged/disengaged with/from four (4) notched recesses defined on inner walls of the four (4) output gears 86-89, respectively. Within the cylindrical shaft portion of the output shaft 64, a shift key 91 is operable to engage one of the clutch balls 90 with the notched recess associated therewith to selectively engage one of the four (4) output gears 86-89 with the output shaft 64 to be rotatable in unison with the output shaft 64.

Thus, in operation of the work implement gearshift transmission 60, the pair of the input gears 65, 66 are slid by a slidable shift shaft 67 so that one of the input gears 65, 66 comes into engagement with one of the change speed gears 81 or 85 on the intermediate transmission shaft 63 associated therewith. A shift shaft 92 has the shift key 91 connected thereto at one end thereof. In response to a sliding operation of the shift key 91 by the shift shaft 92, one of the four (4) output gears 86-89 is selectively engaged with the output shaft 64 to be rotatable in unison with each other, so that the work implement oriented driving force transmitted from the auxiliary gearshift transmission 40 is changed to one of eight (8) speeds to be transmitted to the work implement oriented output shaft 35c.

In particular, when the larger diameter input gear 65 is meshed with the change speed gear 81, the driving force transmitted from the work implement oriented output gear 48 of the auxiliary gearshift transmission 40 for rotating the input shaft 62 is changed in speed by the input gear 65 and the change speed gear 81 to be transmitted to the intermediate transmission shaft 63. On the other hand, when the smaller diameter input gear 66 is meshed with the change speed gear 85, the driving force on the input shaft 62 is changed in speed by the input gear 66 and the change speed gear 85 to be transmitted to the intermediate transmission shaft 63 with a different speed ratio from one provided by the larger diameter input gear 65 and the change speed gear 81. When the larger diameter input gear 65 is meshed with the change speed gear 81, the rotational speed on the intermediate transmission shaft 63 becomes higher than one when the smaller input gear 66 is meshed with the change speed gear 85.

Each of the four (4) gear pairs G1-G4 is selectively switched over between an engaged state and a disengaged state by engaging one of the output gears 86-89 with the output shaft 64. When engaged, the driving force on the intermediate transmission shaft 63 is changed in speed at the speed ratio corresponding to one of the gear pairs G1-G4 to be transmitted to the output shaft 64. The four (4) gear pairs G1-G4 have different speed ratios from one another. That is, the rotational speed on the output shaft 64 becomes different when the intermediate transmission shaft 63 and the output shaft 64 are rotated under their operative interconnection by one of the gear pairs G1~G4, since the gear pairs G1~G4 have different gear ratios from one another for operatively connecting the intermediate transmission shaft 63 with the output shaft 64.

Thus, the work implement gearshift transmission 60 is configured to change the outputted work implement oriented force outputted from the auxiliary gearshift transmission 40 into eight (8) speeds to be transmitted to the implement work section 4, to thereby provide one of eight (8) pitches in the propelling direction between two adjacent seedlings planted by the six (6) seedling planting mechanism 22.

Fig. 7 is a view in vertical section showing a portion of the transmission case 35 housing the auxiliary gearshift transmission 40, the propelling device auxiliary gearshift transmission 50 and the front wheel differential mechanism 70. A shown in Fig. 7, the input shaft 41 and the output shaft 42 in the auxiliary gearshift transmission 40; and the output shaft 53 in the propelling device auxiliary gearshift transmission 50 are arranged side by side with inclination upwardly of the front wheel output shaft 71 in the front wheel differential mechanism 70. The output shaft 53 in the propelling device auxiliary gearshift transmission 50 is located rearwardly and upwardly of the front wheel output shaft 71 in the front wheel differential mechanism 70. With these positional relationships, the auxiliary gearshift transmission 40, the propelling device auxiliary gearshift transmission 50 and the front wheel differential mechanism 70 are housed within the transmission case 35.

Modified Embodiments

(1) In the foregoing embodiment, each of the auxiliary gearshift transmission 40 and the propelling device auxiliary gearshift transmission 50 is operable to provide two speeds, but this is not limitative. Instead thereof, at least one of the auxiliary gearshift transmission 40 and the propelling device auxiliary gearshift transmission 50 may be configured to provide three (3) or more speeds.

(2) In the foregoing embodiment, the work implement gearshift transmission 60 has four (4) gear pairs G1-G4, but this is not limitative. Instead thereof, the work implement gearshift transmission 60 may have three (3) gear pairs, or five (5) or more gear pairs.

(3) In the foregoing embodiment, in the gearshift transmission section 80, the change speed gears 82-84 are mounted on the intermediate transmission shaft 63 and connected thereto to be rotatable in unison with the intermediate transmission shaft 63; and the output gears 86-89 are mounted on the output shaft 64 to come into engagement/disengagement with/from the output shaft 64, but this is not limitative. Instead thereof, the change speed gears, mounted on the intermediate transmission shaft 63, may come into engagement/disengagement with/from the intermediate transmission shaft 63; and the output gears, mounted on the output shaft 64, may be connected thereto to be rotatable in unison with the output shaft 64.

(4) The invention has applications to not only a paddy field work machine with an implement work section configured to perform a seedling planting operation, but also another type of paddy field work machine having another type of implement work section configured to perform a seed sowing operation.

DESCRIPTION OF REFERENCE SIGNS

1 propelling device (front wheels)

2 propelling device (rear wheels)

4 implement work section

10 riding type driving section

10 A driving section

10 B steering section

11 driver's seat

15 steering wheel

30 engine

35 transmission case

36 main change speed device

40 auxiliary gearshift transmission

49 auxiliary shift tool

50 propelling device auxiliary gearshift transmission

57 propelling device auxiliary shift tool

60 work implement gearshift transmission

62 input shaft

63 intermediate transmission shaft

64 output shaft

65, 66 input gear

80 gearshift transmission section

81, 85 change speed gear

G2,G3, G4 gear pair

What is claimed is:-

1. A paddy field work machine comprising:

a riding type driving section (10);

a main change speed device (36) configured to change in speed of a driving force from an engine (30); and

a transmission case (35) configured to receive the driving force from the main change speed device (36) for outputting the inputted driving force to a propelling device (1, 2) and an implement work section (4);

characterized in that

the transmission case (35) houses an auxiliary gearshift transmission (40), a work implement gearshift transmission (60) and a propelling device auxiliary gearshift transmission (50);

the auxiliary gearshift transmission (40) is configured to change in speed of the driving force from the main change speed device (36) to one of a plurality of speeds, and to divide and output the driving force into a work implement oriented force and a propelling device oriented force;

the work implement gearshift transmission (60) is configured to change in speed of the outputted work implement oriented force to one of a plurality of speeds, and to output the force to the implement work section (4); and

the propelling device auxiliary gearshift transmission (50) is configured to change in speed of the outputted propelling device oriented force into one of a plurality of speeds, and to output the force to the propelling device (1, 2).

2. The paddy field work machine according to claim 1,

wherein the riding type driving section (10) includes: a driver's seat side operating section (10A) having a driver's seat (11), and a steering wheel side operating section (10B) having a steering wheel (15); and

wherein the steering wheel side operating section (10B) includes an auxiliary shift tool (49) for shifting the auxiliary gearshift transmission (40).

3. The paddy field work machine according to claim 1 or 2,

wherein the riding type driving section (10) includes: a driver's seat side operating section (10A) having a driver's seat (11), and a steering wheel side operating section (10B) having a steering wheel (15); and

wherein the driver's seat side operating section (10A) includes a propelling device auxiliary shift tool (57) for shifting the propelling device auxiliary gearshift transmission (50).

4. The paddy field work machine according to any one of claims 1-3,

wherein the work implement gearshift transmission (60) includes:

an input shaft (62);

a pair of input gears (65, 66) supported on the input shaft (62) to be rotatable in unison with and slidable relative to the input shaft (62); and

a gearshift transmission section (80); and wherein, when one of the pair of input gears (65, 66) is engaged with a pair of change speed gears (81, 85) of the gearshift transmission section (80), the work implement gearshift transmission (60) is configured
to change in speed of the driving force of the pair of change speed gears (81, 85) to one of a plurality of speeds and transmitting the driving force to an output shaft (64).

5. The paddy field work machine according to claim 4, wherein the gearshift transmission section (80) includes:

an intermediate transmission shaft (63) supporting the pair of change speed gears (81, 85) to be rotatable in unison therewith;

the output shaft (64); and

a gear pair (G2, G3, G4) extending between the output shaft (64) and a portion of the intermediate transmission shaft (63) extending between the pair of change speed gears (81, 85) for changing in speed of the driving force of the intermediate transmission shaft (63) and outputting the driving force to the output shaft (64).