JP4750516B2 - Paddy field work vehicle - Google Patents

Description

  The present invention relates to a paddy field work vehicle such as a riding rice transplanter or a riding direct sowing machine.

A riding rice transplanter, which is an example of a paddy field work vehicle, is equipped with a hydraulic cylinder that drives the seedling planting device up and down and a hydraulic power steering mechanism, and a hydraulic pump that supplies hydraulic oil to the hydraulic cylinder and power steering mechanism. I have.
In this case, as disclosed in Patent Document 1, a transmission case (8 in FIGS. 2, 4 and 6 of Patent Document 1) is provided at the front of the machine body, and a hydraulic pump (Patent) The drive shaft (92 in FIGS. 2, 4 and 6 of Patent Document 1) is provided with the power of the engine (FIG. 2 in FIG. 2 and 15 in FIG. 6). Is configured to be transmitted via a transmission belt.

Japanese Patent Laid-Open No. 10-288150 (FIGS. 2, 4, and 6)

  When a drive shaft is connected to a hydraulic pump, the drive shaft is generally configured to be connected by a spline structure, and it is necessary to sufficiently lubricate a spline portion that connects the hydraulic pump and the drive shaft. In Patent Document 1, since the drive shaft is provided outside the transmission case, grease is also applied to the spline portion that connects the hydraulic pump and the drive shaft.

However, in Patent Document 1, since the drive shaft and the spline portion that connects the hydraulic pump and the drive shaft are close to the outside, grease is likely to disappear, and the grease is likely to disappear at the spline portion that connects the hydraulic pump and the drive shaft. If insufficient, wear may rapidly develop in the spline part connecting the hydraulic pump and the drive shaft. This creates a need to replenish grease frequently.
In the paddy field vehicle, when the drive shaft is connected to the hydraulic pump and the power of the engine is transmitted to the drive shaft, the spline portion connecting the hydraulic pump and the drive shaft is sufficiently lubricated. The purpose is to be able to

[I]
(Constitution)
The first feature of the present invention is that the paddy field vehicle is configured as follows.
A mission case is provided at the front of the aircraft, and a hydraulic pump is provided at the upper part of one lateral side of the mission case. A hydrostatic continuously variable transmission is provided on the other lateral side of the transmission case, and the engine power is transmitted to the input shaft of the hydrostatic continuously variable transmission. The drive shaft connected to the hydraulic pump extends to the other lateral side of the mission case along the left-right direction inside the mission case, and the input shaft and drive shaft of the hydrostatic continuously variable transmission are connected to the mission case. It connects internally and is comprised so that the motive power of an engine may be transmitted to a drive shaft. A steering handle is provided on the upper side of the mission case, and the steering shaft interlocked with the steering handle is inclined so that the lower side is located on the front side of the upper side so as to be close to the drive shaft inside the mission case. The steering shaft is passed through the front wall of the transmission case and the drive shaft, and is tilted vertically along the front wall of the transmission case so as to extend along the entire length. The right and left front wheels are configured to be steerable.

(Function)
When the drive shaft is connected to the hydraulic pump and the engine power is transmitted to the drive shaft, according to the first feature of the present invention, the drive shaft and the spline portion connecting the hydraulic pump and the drive shaft are provided. It will be placed inside the mission case.
A mission case having a relatively large volume is generally filled with lubricating oil to form an oil bath. Therefore, as in the first feature of the present invention, a drive shaft or a spline portion that connects the hydraulic pump and the drive shaft is provided. By arranging it inside the transmission case, the spline connecting the drive shaft and the hydraulic pump and the drive shaft is sufficiently lubricated by the lubricating oil, and the spline connecting the hydraulic pump and the drive shaft is external In other words, the grease (lubricating oil) is not easily exposed to the surface.

Some paddy work vehicles have a steering handle on the upper side of a mission case, and the right and left front wheels are configured to be steerable via a steering shaft that is linked to the steering handle.
According to the first feature of the present invention, the steering shaft is arranged in the vertical direction so as to be close to the drive shaft inside the transmission case. Thus, by arranging the drive shaft in the left-right direction and the steering shaft in the up-down direction to intersect, the drive shaft while avoiding mutual interference between the bearing supporting the drive shaft and the bearing supporting the steering shaft. And the steering shaft can be arranged close to each other.
The paddy field vehicle is equipped with a hydrostatic continuously variable transmission on the side of the transmission case, and the engine power is transmitted to the input shaft of the hydrostatic continuously variable transmission. Some are configured to be transmitted from the shaft to the transmission inside the transmission case. If comprised in this way, the input shaft of a hydrostatic continuously variable transmission will be arrange | positioned close to the wall part of a mission case by providing a hydrostatic continuously variable transmission in the edge part of the side part of a mission case. It becomes possible.
According to the first feature of the present invention, the input shaft and the drive shaft of the hydrostatic continuously variable transmission are connected inside the transmission case, and the power of the engine is transmitted to the drive shaft. The steering shaft passes between the drive case and the front wall of the transmission case that is inclined so that the lower side is located on the front side of the upper side, and extends over the entire length of the front wall of the transmission case. It is inclined in the vertical direction and arranged in the vertical direction. As described above, by effectively using the space between the wall portion in front of the transmission case and the drive shaft, the steering shaft can be appropriately arranged without wasting the internal space of the transmission case. .

(The invention's effect)
According to the first feature of the present invention, when a drive shaft is connected to the hydraulic pump and the engine power is transmitted to the drive shaft in the paddy field work vehicle, the drive shaft, the hydraulic pump and the drive shaft are The spline part to be connected can be sufficiently lubricated by the lubricating oil, and the wear of the spline part to connect the hydraulic pump and the drive shaft can be suppressed. I was able to improve.
According to the first feature of the present invention, the drive shaft and the steering shaft described above can be disposed close to each other, and a useless space between the drive shaft and the steering shaft can be reduced. It became advantageous in terms of compactness.
According to the first aspect of the present invention, when the lateral side portion of the transmission case is provided with a hydrostatic continuously variable transmission and the input shaft and the drive shaft of the hydrostatic continuously variable transmission are connected inside the transmission case. In addition, the steering shaft can be appropriately arranged without wasting the space inside the transmission case, which is advantageous in terms of downsizing the transmission case.

[II]
(Constitution)
The second feature of the present invention resides in the following configuration in the paddy field work vehicle of the first feature of the present invention.
A steering shaft equipped with a steering member for steering the front wheels is provided on the rear side of the lower part of the steering shaft in parallel with the steering shaft, and the gears of the steering shaft and the steering shaft are engaged in the transmission case. Thus, the steering member is swung by the steering shaft, and the front wheels are steered.

[III]
(Constitution)
The third feature of the present invention resides in the following configuration in the paddy field work vehicle of the first or second feature of the present invention.
An oil passage member that returns hydraulic oil overflowed from the hydrostatic continuously variable transmission to a predetermined position is provided inside the transmission case.

(Function)
According to the third feature of the present invention, as in the second feature of the present invention, the “action” described in the preceding paragraphs [I] and [II] is provided. In addition, the following “action” is provided. Yes.
When the paddy work vehicle is equipped with a hydrostatic continuously variable transmission as described in [II] above, the lubricating oil in the transmission case is supplied to the hydrostatic continuously variable transmission as hydraulic fluid. There are many. In this case, if an oil passage member (pipe, hose, etc.) that returns the hydraulic oil overflowed from the hydrostatic continuously variable transmission to a predetermined position is provided outside the transmission case, the hydraulic oil does not leak from the oil passage member. It is necessary to perform a sufficient sealing process on the oil passage member.

  According to the third feature of the present invention, when an oil passage member (pipe, hose, etc.) for returning the hydraulic oil overflowed from the hydrostatic continuously variable transmission device to a predetermined position is provided, the oil passage member is provided inside the transmission case. Yes. Thereby, even if the hydraulic oil leaks from the oil passage member, it only returns to the inside of the transmission case, and therefore it is not necessary to perform a sufficient sealing process on the oil passage member.

(The invention's effect)
According to the third feature of the present invention, the “effect of the invention” described in the preceding paragraphs [I] and [II] is provided in the same manner as the second feature of the present invention. In addition, the following “effect of the invention” is provided. Is provided.
According to the third aspect of the present invention, when an oil passage member (pipe, hose, etc.) for returning the hydraulic oil overflowed from the hydrostatic continuously variable transmission device to a predetermined position is provided, the oil passage member needs to be sufficiently sealed. It became advantageous in terms of simplification of the structure and reduction of production costs.

[IV]
(Constitution)
The fourth feature of the present invention resides in the following configuration in the paddy field work vehicle of the third feature of the present invention.
A front axle case is connected to the transmission case, a front wheel is supported on the front axle case in a freely steerable manner, and a predetermined position where hydraulic fluid overflowed from the hydrostatic continuously variable transmission is returned is defined as the front axle case.

(Function)
According to the fourth feature of the present invention, the “action” described in the preceding paragraphs [I] to [III] is provided in the same manner as the third feature of the present invention. In addition, the following “action” is provided. ing.
According to the fourth feature of the present invention, the hydraulic oil that has overflowed from the hydrostatic continuously variable transmission is returned to the front axle case via the oil passage member, and returns from the front axle case to the transmission case. In this way, the hydraulic oil overflowed from the hydrostatic continuously variable transmission is not returned to the transmission case immediately, but is returned to the transmission case via the front axle case. Cooling can be expected (because the front axle case has an elongated shape and a relatively large surface area).

(The invention's effect)
According to the fourth feature of the present invention, as in the third feature of the present invention, the “effect of the invention” described in the preceding paragraphs [I] to [III] is provided. In addition, the following “invention” is provided. Effect.
According to the fourth aspect of the present invention, it is possible to expect cooling of the hydraulic oil that has overflowed from the hydrostatic continuously variable transmission, so that deterioration of the hydraulic oil can be suppressed, and durability of the paddy field work vehicle is improved. I was able to.

[1]
As shown in FIG. 1, a link mechanism 3 and a hydraulic cylinder 4 that drives the link mechanism 3 to move up and down are provided at the rear part of the airframe having right and left front wheels 1 and right and left rear wheels 2. A seedling planting device 5 is supported at the rear of the mechanism 3 to constitute a riding type rice transplanter as an example of a paddy field work vehicle.

  As shown in FIG. 1, the seedling planting device 5 includes a transmission case 6, a planting case 7 that is rotatably supported at the rear part of the transmission case 6, and a pair of plantings provided at both ends of the planting case 7. The arm 8, the grounding float 9, and the seedling platform 10 are provided. As a result, the planting case 7 is rotationally driven as the seedling platform 10 is driven to reciprocate laterally to the left and right, and the planting arm 8 alternately takes out the seedlings from the lower part of the seedling platform 10 and puts them on the rice field. Plant.

  As shown in FIG. 1, a hopper 12 for storing fertilizer and a feeding portion 13 are fixed to the rear side of the driver seat 11, and a blower 14 is provided below the driver seat 11. A groover 15 is provided in the ground float 9, and a hose 16 is connected across the feeding portion 13 and the groover 15. As a result, the fertilizer is fed from the hopper 12 by a predetermined amount by the feeding section 13 along with the seedling planting as described above, and the fertilizer is supplied to the groove producing device 15 through the hose 16 by the blower 14 blowing. Yes, fertilizer is supplied to the rice field through the groove producing device 15. By storing the seed pods in the hopper 12 instead of the fertilizer, a direct sowing operation for supplying the seed potatoes from the hopper 12 to the rice field via the groove producing device 15 can also be performed (in this case, the seedling planting device 5 is stopped). .

[2]
Next, the transmission structure to the right and left front wheels 1 and the right and left rear wheels 2 in the mission case 17 will be described.
As shown in FIG. 1, a mission case 17 is fixed to the front part of the aircraft, and an engine 19 is supported on a support frame 18 connected to the front part of the mission case 17. The right and left front axle cases 20 are connected to the right and left lateral sides of the mission case 17 so that the right and left front wheels 1 can be steered around the vertical axis of the right and left front axle cases 20. It is supported by.

  As shown in FIGS. 1 and 2, a hydrostatic continuously variable transmission 21 is connected to an upper front portion of the left side portion of the mission case 17, and the power of the engine 19 is hydrostatic continuously variable. It is transmitted to the input shaft 21a of the device 21 via a transmission belt (not shown). The hydrostatic continuously variable transmission 21 has a neutral stop position, and is configured to be continuously variable on the forward side and the reverse side. As shown in FIGS. 2 and 3, the input shaft 21 a and the output shaft 2 b of the hydrostatic continuously variable transmission 21 enter the interior of the transmission case 17, and are moved back and forth (hydrostatic non-static). The input shaft 21a of the step transmission 21 is disposed on the front side, and the output shaft 2b of the hydrostatic continuously variable transmission 21 is disposed on the rear side. The input shaft 21a of the hydrostatic continuously variable transmission 21 is the transmission case 17. It is located in the upper part of the front part of the transmission case 17 and is close to the front wall part 17 a of the mission case 17.

  2 and 3, the transmission shaft 22 is rotatably supported by a transmission case 17 via a bearing 23, and the output shaft 21b and the transmission shaft 22 of the hydrostatic continuously variable transmission 21 are splined. Connected by. A low-speed gear 24 and a high-speed gear 25 are fixed to the transmission shaft 22, and a shift gear 27 is externally fitted to the transmission shaft 26 arranged in parallel with the transmission shaft 22 so as to rotate and slide integrally with the transmission shaft 26 in a spline structure. Has been. As a result, the shift gear 26 is slid and engaged with the low speed gear 24 and the high speed gear 25, so that the power of the transmission shaft 22 is shifted in two steps to be transmitted to the transmission shaft 26.

  As shown in FIGS. 2 and 3, a pair of transmission shafts 28 are arranged to face each other across the transmission case 17 and the right and left front axle cases 20, and a differential mechanism 29 is provided between the pair of transmission shafts 28. A case 29 a of the differential mechanism 29 is supported by the transmission case 17 through a bearing 33 so as to be rotatable. A transmission gear 30 is fixed to the transmission shaft 26, and a transmission gear 31 fixed to the case 29 a of the differential mechanism 29 is engaged with the transmission gear 30.

  As shown in FIG. 2, a cylindrical member 32 is externally fitted to one transmission shaft 28 by a key structure so as to be integrally rotatable and slidable, and is linked to an operation shaft 41 that slides the cylindrical member 32, and the operation shaft 41. A differential lock pedal (not shown) is provided. Accordingly, when the diff lock pedal is depressed, the operation shaft 41 is rotated, the cylindrical member 32 is slid and engaged with the end of the case 29a of the differential mechanism 29, and the cylindrical member 32 is engaged with the case of the differential mechanism 29. By engaging the end of 29a, the differential mechanism 29 can be locked.

As shown in FIG. 2, a traveling output shaft 34 is provided at the rear part of the mission case 17 and protrudes rearward, and a bevel gear 35 fixed to the case 29 a of the differential mechanism 29 is connected to the bevel gear 35 provided on the traveling output shaft 34. Bites 36. As shown in FIG. 1, a rear axle case 37 that supports the right and left rear wheels 2 is provided, and a transmission shaft 38 extends across a travel output shaft 34 and an input shaft (not shown) of the rear axle case 37. Is connected.
Thereby, as shown in FIGS. 1 and 2, the power of the output shaft 21 b of the hydrostatic continuously variable transmission 21 is transferred to the right and left front wheels via the transmission shafts 22 and 26, the differential mechanism 29, and the transmission shaft 28. 1 and transmitted to the right and left rear wheels 2 via the case 29a of the differential mechanism 29, the travel output shaft 34, and the transmission shaft 38.

  As shown in FIG. 2, a plurality of friction plates 39 are provided between the wall portion inside the mission case 17 and the travel output shaft 34, and the disk-shaped operation member 40 is attached to the travel output shaft 34 so as to be relatively rotatable. An operating shaft 42 that slides the operating member 40 and a brake pedal (not shown) linked to the operating shaft 42 are provided, and the brake pedal and the hydrostatic continuously variable transmission 21 are mechanically connected. It is linked to. Thus, when the brake pedal is depressed, the hydrostatic continuously variable transmission 21 is operated to the neutral stop position, the operation shaft 42 is rotated, the operation member 40 is slid, and the operation member 49 is moved to the friction plate. 39 is pressed, and the traveling output shaft 34 is braked. When the travel output shaft 34 is braked, the right and left front wheels 1 are braked via the differential mechanism 29 and the transmission shaft 28, and the right and left rear wheels are connected via the travel output shaft 34 and the transmission shaft 38. The wheel 2 is braked.

[3]
Next, the transmission structure to the seedling planting device 5 in the mission case 17 will be described.
As shown in FIG. 2, a cylindrical transmission gear 43 is externally fitted to the transmission shaft 22 via a one-way clutch 44, and the forward driving power of the output shaft 21 b of the hydrostatic continuously variable transmission 21 by the one-way clutch 44. Is transmitted to the transmission gear 43, and the reverse power of the output shaft 21 b of the hydrostatic continuously variable transmission 21 is not transmitted to the transmission gear 43 by the one-way clutch 44.

  As shown in FIGS. 2, 3 and 5, the transmission gear 45 and the six transmission gears 46 are connected to each other so as to rotate integrally, and the transmission gear 45 and the six transmission gears 46 are rotated relative to the transmission shaft 26. It is freely fitted and the transmission gears 43 and 45 are engaged. Six transmission gears 48 are fitted on a transmission shaft 47 arranged in parallel with the transmission shaft 26 so as to be relatively rotatable, and the six transmission gears 46 and the transmission gears 48 are engaged with each other. An operation rod 49 is provided which selects one of the transmission gears 48 and can be connected to and disconnected from the transmission shaft 47. As described above, the stock transmission 50 is configured by the six transmission gears 46, the transmission gear 48, the operation rod 49, and the like, and the transmission rod 48 is one of the six transmission gears 48 by the operation rod 49. Is selected and coupled to the transmission shaft 47, the power of the transmission shaft 26 is shifted to six stages and transmitted to the transmission shaft 47.

As shown in FIG. 5, an output shaft 51 is provided at the upper portion of the rear portion of the transmission case 17 and protrudes rearward. A bevel gear 52 that is externally fitted to the output shaft 51 so as to be relatively rotatable is fixed to the transmission shaft 47. The bevel gear 53 is engaged. The shift member 54 is externally fitted to the output shaft 51 so as to be rotatable and slidable integrally with the output shaft 51 by a spline structure, and a spring 55 is provided to bias the shift member 54 to the occlusal side with the bevel gear 52, and the shift member 54 is separated from the bevel gear 52. An operation rod 56 for operation is provided, and a planting clutch 57 that can transmit and shut the power of the transmission shaft 47 to and from the output shaft 51 is configured. As shown in FIGS. 1 and 5, a transmission shaft 58 is connected across the output shaft 51 and an input shaft (not shown) of the seedling planting device 5.
Thereby, as shown in FIGS. 1, 2, and 5, the power of the transmission shaft 26 is applied to the seedling planting device via the inter-shaft transmission 50, the bevel gears 52 and 53, the planting clutch 57, the output shaft 51, and the transmission shaft 58. 5 is transmitted.

[4]
Next, the transmission structure of the hydraulic pump 59 in the transmission case 17 will be described.
As shown in FIGS. 2, 3, and 4, a hydraulic pump 59 is connected to an upper front portion on the right lateral side of the mission case 17, and an input shaft 59 a of the hydraulic pump 59 enters the inside of the mission case 17. It is out. The input shaft 21 a of the hydrostatic continuously variable transmission 21 and the input shaft 59 a of the hydraulic pump 59 are arranged concentrically, and the input shaft 59 a of the hydraulic pump 59 is located in the upper part of the front portion of the transmission case 17. And close to the wall 17a in front of the mission case 17.

  As shown in FIGS. 2, 3, and 4, a drive shaft 60 is disposed across the input shaft 21 a of the hydrostatic continuously variable transmission 21 and the input shaft 59 a of the hydraulic pump 59. The input shaft 21a of the device 21 and the drive shaft 60 are connected by a spline structure via a cylindrical connecting member 61, and the input shaft 59a and the drive shaft 60 of the hydraulic pump 59 are connected via a cylindrical connecting member 62. Has been. As a result, the drive shaft 60 is arranged along the left-right direction inside the mission case 17 and is arranged along the wall portion 17 a in front of the mission case 17. As a result, as described in [2] above, the power of the engine 19 is transmitted to the input shaft 21a of the hydrostatic continuously variable transmission 21, and is transmitted to the hydraulic pump 59 via the drive shaft 60. 59 is driven.

  As shown in FIGS. 2, 3, and 4, the mission case 17 is filled with lubricating oil, and the mission case 17 is formed into an oil bath. The oil level of the mission case 17 is determined by a hydrostatic continuously variable transmission 21. Are set slightly above the input shaft 21a and the output shaft 21b. The transmission shafts 26 and 47 and the inter-variety transmission device 50, the output shaft 51, the differential mechanism 29 and the transmission shaft 28, the right and left front positions are positioned lower than the input shaft 21a and the output shaft 21b of the hydrostatic continuously variable transmission 21. An axle case 20 and a travel output shaft 34 are disposed. As described in [5], which will be described later, a hydraulic power steering mechanism 63 is connected to the upper portion of the front portion of the transmission case 17, and a breather pipe 76 having an opening 76 a at the upper portion is connected to the power steering mechanism 63. Provided on the front side, an oil level gauge 77 is provided on the rear side of the power steering mechanism 63.

  As shown in FIGS. 2, 3 and 4, boss portions 17 b and 17 c surrounding the input shaft 21 a and the output shaft 21 b of the hydrostatic continuously variable transmission 21 are provided in the transmission case 17, and the input shaft 59 a of the hydraulic pump 59 is connected to the transmission case 21. A surrounding boss portion 17 d is provided in the mission case 17, and a pair of semicircular cutout portions 17 e are formed on the inner peripheral portion of the boss portion 17 b of the mission case 17.

  As a result, as shown in FIGS. 2, 3, and 4, the drive shaft 60 is in the lubricating oil of the transmission case 17, and the transmission is connected to the spline portion that connects the drive shaft 60 and the connecting members 61 and 62. The lubricating oil of case 17 enters. The lubricating oil in the transmission case 17 passes through the bearing 23 and enters the boss portion 17c of the transmission case 17, and the transmission case 17 is connected to the spline portion that connects the output shaft 21b and the transmission shaft 22 of the hydrostatic continuously variable transmission 21. Of lubricating oil.

  As shown in FIGS. 2, 3, and 4, the lubricating oil in the mission case 17 passes through the notch 17 e of the mission case 17 and the gap between the boss 17 b of the mission case 17 and the connecting member 61. The lubricating oil of the transmission case 17 enters the spline portion connecting the input shaft 21a of the hydrostatic continuously variable transmission 21 and the connecting member 61. The lubricating oil in the mission case 17 passes through the gap between the boss portion 17 d of the mission case 17 and the connecting member 62 and enters the boss portion 17 d of the mission case 17, and the input shaft 59 a of the hydraulic pump 59 and the connecting member 62. The lubricating oil of the transmission case 17 enters the spline portion connecting the two.

[5]
Next, the steering structure of the right and left front wheels 1 will be described.
As shown in FIGS. 2, 3, and 4, a hydraulic power steering mechanism 63 is connected to an upper portion of the front portion of the transmission case 17, and a steering handle 64 (see FIG. 1) is disposed above the transmission case 17 and the power steering mechanism 63. The power steering mechanism 63 and the steering handle 64 are coupled to each other via a steering shaft (not shown).

  As shown in FIGS. 2, 3, and 4, the steering shaft 65 passes vertically between the front wall portion 17 a of the transmission case 17 and the drive shaft 60 along the front wall portion 17 a of the transmission case 17. In the transmission case 17, the drive shaft 60 disposed along the left-right direction and the steering shaft 65 disposed along the vertical direction intersect with each other.

  As shown in FIGS. 3 and 4, a gear 65 a is formed at the lower portion of the steering shaft 65, and the lower portion of the steering shaft 65 is rotatably supported by the transmission case 17 via a bearing 66. A boss 65b is connected to the upper portion of the steering shaft 65 by a spline structure, and the boss 65b of the steering shaft 65 is rotatably supported by a boss 17f of the transmission case 17 via a bush 67. The output shaft 63a and the boss portion 65b of the steering shaft 65 are connected by a spline structure.

  As shown in FIG. 3, a steering shaft 68 is rotatably supported at the lower portion of the mission case 17, and a gear 68 a fixed to the upper portion of the steering shaft 68 is engaged with the gear 65 a of the steering shaft 65. A tie rod (not shown) is connected across the steering member 68 b fixed to the lower portion of the direction shaft 68 and the right and left front wheels 1. Thus, when the steering handle 64 is operated, the steering shaft 65 is rotated through the power steering mechanism 63, the steering member 68b of the steering shaft 68 is swung, and the right and left front wheels 1 are steered. Operated.

As shown in FIG. 4, a filter 70 is connected to the lower front portion of the right side portion of the mission case 17, and an internal oil passage 17 g formed on the right side portion (wall portion) of the mission case 17. Is connected from the filter 70 to the hydraulic pump 59. Is connected hydraulic pipe 71 is over the hydraulic pump 59 and the power steering mechanism 63, hydraulic Siri Sunda 4 control valve for supplying and discharging operating the hydraulic oil (refer to FIG. 1) (not shown), the power steering mechanism A hydraulic pipe 72 is connected to 63.

  As a result, as shown in FIG. 4, the lubricating oil in the mission case 17 is sucked into the filter 70 from the suction port (not shown) as working oil, and the hydraulic pump passes through the internal oil passage 17 g of the mission case 17 from the filter 70. 59. The hydraulic oil of the hydraulic pump 59 is supplied to the power steering mechanism 63 via the hydraulic pipe 71 and is supplied to the control valve via the hydraulic pipe 72 and is returned from the control valve to the transmission case 17.

As shown in FIG. 3 and FIG. 4, the inside of the transmission case 17 is extended from a pipe 73 that discharges hydraulic oil that has overflowed from the hydrostatic continuously variable transmission 21, and the pipe 73 is located on the left side of the transmission case 17. Along the inner surface of the side portion (wall portion), it extends downward between the drive shaft 60 and the transmission shaft 26 and extends rearward, and is connected to the left front axle case 20. A U-shaped receiving portion 17 h is integrally formed on the inner surface of the left lateral side (wall portion) of the mission case 17, and a pipe 73 is inserted into the receiving portion 17 h of the mission case 17. The pipe 73 is fixed by the washer 75.
As a result, as shown in FIGS. 2, 3, and 4, the hydraulic oil overflowed from the hydrostatic continuously variable transmission 21 is returned to the left front axle case 20 through the pipe 73, and the left front axle case Twenty hydraulic fluids return to the inside of the mission case 17 through the bearings 33.

[First Alternative Embodiment of the Invention]
In the above-mentioned [Best Mode for Carrying Out the Invention], the vicinity of the input shaft 21a, the output shaft 21b, and the hydraulic pump 59 of the hydrostatic continuously variable transmission 21 of FIG. 2 is configured as shown in FIG. Also good.
As shown in FIG. 6, the drive shaft 60 is rotatably supported by the transmission case 17 via a bearing 78, and the input shaft 21a and the drive shaft 60 of the hydrostatic continuously variable transmission 21 are connected to a connecting member 61 ( The input shaft 59a of the hydraulic pump 59 and the drive shaft 60 are connected by an oval structure without the connection member 62 (see FIG. 2).

  As a result, as shown in FIG. 6, the lubricating oil in the transmission case 17 passes through the bearing 78 and enters the boss portion 17 b of the transmission case 17, and the input shaft 21 a and the drive shaft 60 of the hydrostatic continuously variable transmission 21. The lubricating oil of the transmission case 17 enters the spline portion connecting the two. The lubricating oil of the mission case 17 passes through the bearing 78 and enters the boss portion 17d of the mission case 17, and the lubricating oil of the mission case 17 enters the oval portion connecting the input shaft 59a of the hydraulic pump 59 and the drive shaft 60. .

  As shown in FIG. 6, a transmission gear 79 is fitted on the drive shaft 60 so as to be relatively rotatable, and a shift member 80 is fitted on the drive shaft 60 so as to be integrally rotatable and slidable with the drive shaft 60 in a spline structure. . A transmission gear 81 is disposed between the input shaft 21 a and the output shaft 21 b of the hydrostatic continuously variable transmission 21, and the transmission gear 81 is engaged with the low-speed gear 24 and the transmission gear 79. In the state where the hydrostatic continuously variable transmission 21 is operated to the neutral stop position, the neutral speed stop position to the reverse-side maximum speed position, and the neutral stop position to the forward-side maximum speed position. Is separated from the transmission gear 79 (see FIG. 6). When the hydrostatic continuously variable transmission 21 is operated to the highest speed position on the forward side, the shift member 80 is slid to the left in FIG. 6 and meshes with the transmission gear 79.

  As shown in FIG. 6, when the hydrostatic continuously variable transmission 21 is operated to the highest speed position on the forward side, the input shaft 21a and the output shaft 21b of the hydrostatic continuously variable transmission 21 are at the same speed and in the same direction. The inside of the hydrostatic continuously variable transmission 21 is set so as to rotate. Actually, however, the output shaft 21b is slightly smaller than the input shaft 21a of the hydrostatic continuously variable transmission 21 due to leakage of hydraulic oil or the like. Rotate at low speed. The reduction ratio from the transmission gears 79 and 81 to the low speed gear 24 is set to “1”. As a result, the power transmitted to the input shaft 21 a of the hydrostatic continuously variable transmission 21 by engaging the shift member 80 with the transmission gear 79 at the highest speed position on the forward side of the hydrostatic continuously variable transmission 21. Is transmitted from the output shaft 21b of the hydrostatic continuously variable transmission 21 to the transmission shaft 22 via a hydraulic circuit inside the hydrostatic continuously variable transmission 21, in addition to transmission gears 79, 81 and It is transmitted to the transmission shaft 22 via the low speed gear 24.

  In a pair of oil passages (not shown) connecting a hydraulic pump (not shown) and a hydraulic motor (not shown) of the hydrostatic continuously variable transmission 21, a bypass that connects intermediate portions of the pair of oil passages An oil passage (not shown) (normally closed) is provided, and when the shift member 80 is engaged with the transmission gear 79 at the highest speed position on the forward side of the hydrostatic continuously variable transmission 21, a bypass is provided. The oil passage is operated to open (communication state). This prevents the hydrostatic continuously variable transmission 21 from becoming a resistance to transmission from the input shaft 21a of the hydrostatic continuously variable transmission 21 to the power via the transmission gears 79 and 81 and the low speed gear 24. ing.

[Second Embodiment of the Invention]
In the above-mentioned [Best Mode for Carrying Out the Invention] [First Alternative Embodiment], the transmission case 21 is provided with a hydrostatic continuously variable transmission 21 on the right lateral side of the mission case 17. A hydraulic pump 59 may be provided on the left lateral side. The power steering mechanism 63 may be omitted, and the steering handle 64 and the steering shaft 65 may be interlocked and connected. You may comprise so that the engine 19 may be provided in the lower side of the driver's seat 11, without providing in the front part of a body.

Overall side view of riding rice transplanter Cross-sectional plan view of the mission case Longitudinal side view of the front of the mission case Front view of the front of the mission case Transverse plan view near the output shaft of the mission case Cross-sectional plan view of the front of the mission case in the first alternative embodiment of the invention

DESCRIPTION OF SYMBOLS 1 Front wheel 17 Transmission case 17a Wall part in front of a transmission case 19 Engine 20 Front axle case 21 Hydrostatic continuously variable transmission 21a Input shaft of hydrostatic continuously variable transmission 59 Hydraulic pump 60 Drive shaft 64 Steering handle 65 Steering shaft
65a Steering shaft gear
68 Steering axis
68a Steering shaft gear
68b Steering member 73 for steering the front wheel

Claims (4)

A transmission case is provided at the front part of the fuselage, a hydraulic pump is provided at the top of one lateral side of the transmission case, and a hydrostatic continuously variable transmission is provided at the other lateral side of the transmission case. Power is transmitted to the input shaft of the hydrostatic continuously variable transmission,
A drive shaft connected to the hydraulic pump extends to the other lateral side portion of the transmission case along the left-right direction inside the transmission case, and the input shaft and the drive shaft of the hydrostatic continuously variable transmission In the transmission case, and configured so that the power of the engine is transmitted to the drive shaft,
A steering handle is provided on the upper side of the mission case, and a steering shaft interlocked with the steering handle is inclined so that the lower side is positioned forward than the upper side so as to be close to the drive shaft inside the mission case. Between the drive wall and the front wall portion of the transmission case formed in such a manner that it is inclined vertically along the front wall portion of the transmission case and arranged in the vertical direction, A paddy field work vehicle configured such that the right and left front wheels can be steered by the steering handle via a steering shaft.   A steering shaft having a steering member for steering the front wheel is provided on the rear side of the lower portion of the steering shaft in parallel with the steering shaft, and the gear of the steering shaft and the steering shaft are provided inside the transmission case. The paddy field work vehicle according to claim 1, wherein the steering wheel is operated to swing by the steering shaft so that the front wheels are steered.   3. The paddy field work vehicle according to claim 1, wherein an oil passage member that returns hydraulic oil overflowed from the hydrostatic continuously variable transmission to a predetermined position is provided inside the transmission case.   A front axle case is connected to the transmission case, a front wheel is supported on the front axle case so as to be steerable, and a predetermined position for returning the hydraulic oil overflowed from the hydrostatic continuously variable transmission is defined as the front axle case. The paddy field work vehicle according to claim 3.

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