JP6132756B2 - Work vehicle - Google Patents

Description

  The present invention relates to a work vehicle including a steering shaft that is supported in a state in which a lower end side is inserted into a transmission case, and a pitman arm that is arranged on the lower side of the transmission case.

As described above, the work vehicle described in [1] below is known as a work vehicle in which the steering shaft and the pitman arm are supported by the transmission case.
[1] That is, in the transmission case, the upper end side of the steering shaft is supported by a torque generator fixed to the upper part of the transmission case, and the lower end side is supported by a ball bearing provided on the bottom wall of the transmission case. .
The pinion gear provided on the steering shaft and the sect gear provided on the rotating shaft that rotates together with the pitman arm are engaged with each other at a position slightly above the position supported by the ball bearing. The rotation of the steering shaft is transmitted to the pitman arm by the engagement of the pinion gear and the sect gear (see Patent Document 1).
Also, in this work vehicle, the lower end side of the arm spindle that rotates integrally with the pitman arm is supported by a ball bearing mounted on the bottom wall of the transmission case, and the upper end side is above the sect gear and from the side wall of the transmission case. It is supported by the ball bearing with respect to the extended support part (refer patent document 1).

JP 2007-325528 A (paragraphs [0043, 0044], FIG. 8, FIG. 9)

In the work vehicle described in Patent Document 1, the steering shaft is accurately supported by a ball bearing on the lower end side.
However, on the upper end side, the distance from the engagement of the pinion gear and the sect gear to the support portion on the upper end side becomes long, and there is a possibility that the spline shaft will be bent slightly.
Alternatively, the steering shaft may be supported with respect to the output shaft of the torque generator using a detachable connection structure such as spline fitting, and the spline shaft may be slightly inclined due to rattling generated in the support structure portion. There is.
In this way, if the upper side of the spline shaft tilts even slightly with respect to the lower side due to bending or rattling of the spline shaft, uneven wear tends to occur between the pinion gear and the sect gear at the meshing position between the pinion gear and the sect gear. There is a possibility that it may be a factor of decline, and there is room for improvement in this respect.

  Further, in the work vehicle described in the above-mentioned Patent Document 1, since the lower end side and the upper end side of the arm support pivoting integrally with the pitman arm are both supported by ball bearings, the arm support can be stably provided. It is useful in that it can be supported. However, in this structure, since the support portion of the ball bearing that supports the upper end side of the arm support shaft is extended from the lateral side wall of the mission case, the arm support shaft is mounted from the bottom side of the mission case. At this time, the arm support shaft may be driven from below. In that case, since a large or shocking load may act on the support portion of the ball bearing extended from the lateral side wall of the mission case, the weight of the mission case increases to improve the strength of the support portion. There is room for improvement in this regard.

The present invention is intended to provide a work vehicle capable of improving durability in a power transmission structure between a steering shaft and a pitman arm.
The present invention is intended to improve the support strength at the upper end side support portion of the arm support shaft of the pitman arm while avoiding an increase in the weight of the mission case.

[Solution 1]
The technical means of the working machine according to the present invention taken in order to solve the above problems includes a steering shaft arranged with the lower end side inserted into the transmission case, and a pitman arm arranged below the transmission case. And an arm spindle disposed at the bottom of the transmission case so as to swing the pitman arm, and a pinion gear provided at a lower portion of the steering shaft in the transmission case, and in the transmission case The steering shaft and the arm support shaft are linked to each other and meshed with a steering gear provided on the arm support shaft, and the steering shaft is provided below the pinion gear. The lower first bearing portion and the upper side of the pinion gear at the lower portion of the space inside the transmission case By the provided upper first bearing portion is supported by the upper and lower positions sandwiching said pinion gear, said upper first bearing portion is supported on the shaft side mounting portion extending from the case wall of the transmission case, The shaft side mounting portion is formed across the front wall and the lateral wall of the transmission case, and the arm support shaft is pivotally supported by an upper second bearing portion provided above the steering gear. The shaft-side mounting portion and the arm-side mounting portion, which are supported by the arm-side mounting portion provided on the lateral wall of the transmission case, and extend from the case wall of the transmission case, are the shaft-side mounting portion. And an intermediate connection part located between the arm side mounting part and the intermediate connection part, and the intermediate connection part is formed to project from the inner surface of the lateral wall of the transmission case in a rib shape. And is that is.

[Operation and effect of invention according to Solution 1]
According to the configuration of the present invention according to the above solution 1, the steering shaft includes the lower first bearing portion provided below the pinion gear, and the upper first shaft provided above the pinion gear in the lower portion of the space inside the transmission case. It is supported by the bearing part. That is, the steering shaft is supported at both the upper and lower positions sandwiching the pinion gear in the lower portion of the space inside the transmission case. As a result, the steering shaft is in a state in which the position in the horizontal direction is restricted at both the upper and lower positions near the meshing position of the pinion gear and the sect gear.
Therefore, the possibility that the steering shaft will bend due to the load generated at the meshing position with the sect gear is reduced, and the pinion gear is positioned accurately even if the upper part of the steering shaft has a slightly rattling support structure. Retained. As a result, there is less possibility of uneven wear occurring between the pinion gear and the sect gear, and there is an advantage that the durability of the power transmission structure between the steering shaft and the pitman arm can be improved.

Since the upper first bearing portion is supported by the shaft side mounting portion extending from the case wall of the transmission case, the steering at both the upper and lower positions sandwiching the pinion gear by effectively utilizing the strength of the case wall of the transmission case itself The shaft can be firmly supported.
Therefore, there is an advantage that the support structure of the upper first bearing portion can be firmly configured with a simple structure.
In addition, since the shaft side mounting part that extends from the case wall of the transmission case is formed across the front wall and the lateral wall of the transmission case, the mounting strength of the shaft side mounting part to the case wall can be simplified. There is an advantage that it is easy to keep firmly.

Since the upper second bearing portion is supported by the arm side mounting portion provided on the lateral wall of the transmission case, the arm support disposed at the bottom of the transmission case is utilized by effectively utilizing the strength of the transmission case wall itself. The shaft can be firmly supported. Therefore, there is an advantage that the support structure of the upper second bearing portion can be firmly configured with a simple structure.

The shaft-side attachment portion and the arm-side attachment portion are integrally connected by an intermediate connection portion, whereby the steering shaft supported by the shaft-side attachment portion and the arm support shaft supported by the arm-side attachment portion. There is an advantage that the supporting strength can be further increased.
There is an advantage that the intermediate connection portion can be configured simply by a rib-like member formed to protrude from the inner side wall of the transmission case.

[Solve hand stage 2]
The other technical means of the present invention taken in order to solve the above-mentioned problems are that the transmission case has a box-shaped case main body having an opening formed on one end side in the left-right direction, and a lid for closing the opening. The case-side case portion is configured to be openable and closable, and the shaft-side attachment portion is provided to the case main body portion.

[Action and Effect of the invention according to resolve hand stage 2]
According to the configuration of the invention according to the above solution hand stage 2, the shaft-side mounting portion so provided in the box-shaped case body rather than the cap-like case portion, but easily formed larger shaft side mounting portion itself In addition, it is also possible to provide the shaft side mounting portion so as to function as a reinforcing rib of the box-shaped case main body portion. Therefore, there is an advantage that it is easy to configure a transmission case having a shaft-side mounting portion with a simple structure.

[Solve hand stage 3]
Another technical means of the present invention taken to solve the above problem is that a bottom opening for inserting and removing the steering shaft is formed in the bottom wall of the transmission case, and the lower first bearing portion is provided in the bottom opening. It is that.

[Action and Effect of the invention according to resolve hand stage 3]
According to the configuration of the invention according to the above solution hands stage 3, by utilizing the bottom opening for insertion and removal of the steering shaft as a mounting portion of the lower first bearing part, aims to simplify the mounting structure of the lower first bearing There are benefits to get.

[Solve hand stage 4]
Another technical means of the present invention taken to solve the above problem is that the lower first bearing portion is configured to be detachable from the lower side with respect to the bottom opening, and the inner diameter of the lower first bearing portion is That is, the outer diameter of the lower first bearing portion is smaller than the outer diameter of the pinion gear and larger than the outer diameter of the pinion gear.

[Action and Effect of the invention according to resolve hand stage 4]
According to the configuration of the invention according to the above solution hands stage 4, the inner diameter is smaller than the outer diameter of the pinion gear, by an outer diameter comprises a first bearing portion lower part is formed larger than the outer diameter of the pinion gear, the The lower first bearing portion can prevent the pinion gear from coming off downward. When the lower first bearing portion is removed, the steering shaft can be attached and detached together with the pinion gear.
Therefore, there is an advantage that the steering shaft and the pinion gear can be easily attached and detached.

[Solve hand stage 5]
Another technical means of the present invention taken in order to solve the above problem is that the upper first bearing portion is formed so that an outer diameter thereof is smaller than an inner diameter of the bottom opening. .

[Action and Effect of the invention according to resolve hand stage 5]
According to the configuration of the invention according to the above solution hands stage 5, by removing the lower first bearing part, it can also be desorbed first bearing upper from the bottom opening.
Therefore, it is possible to detach the steering shaft from the bottom opening in a state where the bearing portions are mounted in advance on both the upper and lower sides of the pinion gear of the steering shaft, and there is an advantage that the detaching operation of the steering shaft and the upper and lower bearing portions can be easily performed. .

[Solve hand stage 6]
Another technical means of the present invention taken to solve the above-described problem is that the shaft mounting portion, the arm mounting portion, and the intermediate connection portion are provided to form a bearing mounting portion. As for the portion, the shaft side mounting portion corresponding to the periphery of the steering shaft and the arm side mounting portion corresponding to the periphery of the arm support shaft are formed wider in the left-right direction in plan view than the intermediate connection portion. That's what it means.

[Action and Effect of the invention according to resolve hand stage 6]
According to the configuration of the invention according to the above solution hands stage 6, lateral width in plan view of the shaft-side mounting portion and the arm side attachment portion for supporting the steering shaft or the arm support shaft, in the lateral direction than the intermediate connecting portion Because it is widely formed, the intermediate connection part with a short projecting length in the left-right direction is compact as a whole, and the projecting length is short so that it is easy to maintain a strong support strength against loads in the vertical direction. ing.
Therefore, there is an advantage that the intermediate connection portion having a short projecting length from the case wall of the transmission case can be firmly supported not only in the front-rear direction of the front-rear shaft side attachment portion and the arm-side attachment portion but also in the vertical direction.

[Solve hand stage 7]
Another technical means of the present invention taken to solve the above problem is that the upper end side of the steering shaft is connected to the output shaft of a power steering device provided on the upper side of the transmission case.

[Action and Effect of the invention according to resolve hand stage 7]
According to the configuration of the invention according to the above solution hands stage 7, the power to support the steering shaft to the output shaft of the steering device, regardless of whether such slight backlash in the connection points are present, stably supported by There are benefits to get.

[Solve hand stage 8]
Another technical means of the present invention taken in order to solve the above problems, the arm side attachment portion is that the longitudinal ribs for reinforcement against vertical loads are formed.

[Action and Effect of the invention according to resolve hand stage 8]
According to the configuration of the invention according to the above solution hands stage 8 is supported on the arm side attachment portion of the second bearing portion upper extending from the case wall of the transmission case supporting the upper side of the arm support shaft, the arm Since the attachment portion is provided with vertical ribs for reinforcement against the load in the vertical direction, the strength of the arm side attachment portion with respect to the load in the vertical direction can be improved with a relatively lightweight structure.
Therefore, when avoiding an increase in the weight of the transmission case, when mounting the arm support shaft of the pitman arm on the bottom side of the transmission case, the arm support shaft is driven from the lower side and a large load is applied to the arm side mounting portion from the lower side. Also when it acts, there exists an advantage which becomes easy to suppress damage etc. of an arm side attaching part.

[Solve hand stage 9]
Another technical means of the present invention taken in order to solve the above problem is that the vertical rib is formed across the upper surface of the arm-side mounting portion and the lateral wall of the transmission case.

[Action and Effect of the invention according to resolve hand stage 9]
According to the invention according to the above resolution hand stage 9, longitudinal ribs for reinforcement against vertical load on the arm mounting portion, since it is formed over the lateral wall Metropolitan the top and the transmission case of the arm-side attachment portion, the arm The reinforcing structure of the side mounting portion can be configured simply using the horizontal wall and vertical rib of the transmission case.

[Solve hand stage 10]
Another technical means of the present invention taken in order to solve the above-mentioned problem is that the upper first bearing portion located close to the upper side of the pinion gear is formed on the shaft side formed across the front wall and the lateral wall of the transmission case. It is supported by the mounting portion, and the shaft side mounting portion and the arm side mounting portion are integrally connected to each other by an intermediate connection portion located between the shaft side mounting portion and the arm side mounting portion. That is.

[Action and Effect of the invention according to resolve hand stage 10]
According to the invention according to the above resolution hand stage 10, since the shaft-side mounting portion and the arm side attachment portion are integrally connected by an intermediate connecting portion, the steering shaft, and the arm is supported by the shaft-side mounting portion There is an advantage that the support strength of the arm supporting shaft supported by the side mounting portion can be increased with a simple structure.

[Solve hand stage 11]
Another technical means of the present invention taken in order to solve the above problem is that the vertical ribs are formed at both front and rear positions of the upper second bearing portion.

[Action and Effect of the invention according to resolve hand stage 11]
According to the invention according to the above resolution hand stage 11, there is an advantage that can increase the strength before and after positions on both sides of the second upper bearing portion.

[Solve hand stage 12]
According to another technical means of the present invention taken to solve the above-mentioned problem, the longitudinal rib is formed such that the longitudinal rib on the side farther from the steering shaft is larger than the longitudinal rib on the side close to the steering shaft. That's what it means.

[Action and Effect of the invention according to resolve hand stage 12]
According to the invention according to the above resolution hand stage 12, than the side close longitudinal ribs on the steering shaft, since the longitudinal rib farther from the steering shaft is larger, it is formed smaller either side ribs Compared to the case, the strength and strength can be increased, and when the shaft side mounting portion and the arm side mounting portion are connected by the intermediate connection portion, the side far from the steering shaft that is not connected to the intermediate connection portion There is an advantage that it can be reinforced strongly and durability can be further improved.

[Solve hand stage 13]
Another technical means of the present invention taken in order to solve the above problem is that the vertical ribs are connected to each other by horizontal ribs along the horizontal direction.

[Action and Effect of the invention according to resolve hand stage 13]
According to the invention according to the above resolution hand stage 13, by longitudinal ribs to each other are connected, there is an advantage that may enhance even more strength.

[Solve hand stage 14]
Another technical means of the present invention taken in order to solve the above problems, the longitudinal ribs over transverse wall Prefecture of the transmission case and the upper surface of the arm side attachment portion, formed at both front and rear sides of the upper second bearing portion is, the upper first bearing portion located adjacent to the upper side of the pinion gear, the is supported by the shaft-side mounting portion formed over the front wall and the lateral wall Metropolitan of the transmission case, the arm and its shaft-side mounting portion the side mounting portion, the integrally connected to each other by the intermediate connecting portion located between the shaft-side mounting portion and the arm side attachment portion, than the longitudinal ribs of the side closer to the steering shaft, the steering shaft That is, the vertical ribs on the side far from the center are formed large, and the vertical ribs are connected to each other by horizontal ribs along the horizontal direction.

[Action and Effect of the invention according to resolve hand stage 14]
According to the invention according to the above resolution hand stage 14, the same action and effect as the solutions 8,9,10,11,12, and 13.

It is a right view of a riding type rice transplanter. It is a right view which shows a mission case and a vehicle body frame. It is a top view which shows a mission case. It is a longitudinal cross-sectional view of a mission case. It is sectional drawing which shows the lower bearing location of a steering shaft. It is a perspective view of a mission case main part. It is a diagram which shows the power transmission system to a traveling apparatus. It is a diagram which shows the power transmission system | strain to a seedling planting apparatus.

Hereinafter, an example of an embodiment of the present invention will be described based on the drawings.
〔overall structure〕
FIG. 1 shows a right side surface of a riding type rice transplanter as an example of a work vehicle.
This riding type rice transplanter includes a pair of left and right steering operations and driveable front wheels 11F and a pair of left and right driveable rear wheels 11R below the body frame 10, and an engine E mounted on the body frame 10. The self-propelled traveling vehicle body 1 in which the front wheels 11F and the rear wheels 11R are driven by the power from the vehicle is provided.
The traveling vehicle body 1 is provided with a prime mover 13 with an engine E built in at the front of the fuselage, and reserve seedling platforms 14 are provided on the left and right sides thereof. A boarding driving unit having a steering handle 15 and a driving seat 12 for steering the front wheel 11F is provided at the center in the front-rear direction of the traveling vehicle body 1 on the rear side of the driving unit 13. A seedling planting device 2 is supported at a rear portion of the traveling vehicle body 1 through a link mechanism 17 having a lift cylinder 18 so as to be movable up and down.
The riding type rice transplanter configured in this way performs planting work of seedlings such as rice on the field as “ground work” by the seedling planting device 2.

  The seedling planting device 2 is configured in an eight-row planting type, and includes four transmission cases 21, a planting case 22 supported rotatably on the right and left lateral sides of the rear portion of the transmission case 21, A pair of planting arms 23 provided at both ends of the attached case 22, a grounding float 24, a seedling platform 20 on which a seedling is placed, and the like are provided. As a result, the planting case 22 is rotationally driven as the seedling platform 20 is reciprocated laterally to the left and right, and the planting arm 23 alternately takes out seedlings from the lower part of the seedling platform 20 and puts them on the rice field. Configured to plant.

A transmission case 3 that pivotally supports a front wheel 11F is connected and fixed to the front portion of the vehicle body frame 10 in the traveling vehicle body 1, and a rear transmission case 19 equipped with rear wheels 11R on the left and right is provided at the rear portion of the vehicle body frame 10. It is supported so that it can roll. A front frame 10F extends forward from the mission case 3, and an engine E is mounted sideways on the front frame 10F.
As shown in FIGS. 2 to 4, on the left and right sides of the transmission case 3, the front axle case 3A extends left and right, and left and right front wheels 11F and 11F are provided. A torque generator 4 (corresponding to a power steering device) is provided on the upper side of the transmission case 3, and a steering handle 15 is provided at the upper end of a steering operation shaft 15 a erected upward from the torque generator 4. . A main transmission lever 16 that changes the vehicle speed by operating a hydrostatic continuously variable transmission 61, which will be described later, is disposed on the side of the steering handle 15.

[Power transmission system]
A power transmission system in which the power of the engine E is transmitted to the front wheels 11F and the rear wheels 11R of the travel drive system, and a power transmission system that is transmitted to the seedling planting device 2 as a work device will be described.

[About driving system]
As shown in FIG. 3, a pair of left and right front axle cases 3 </ b> A are provided on the left and right sides of the mission case 3. The front wheel case 3A supports the front wheel 11F so that it can be steered by turning around an axis along the vertical direction.

  As shown in FIGS. 3 and 7, a hydrostatic continuously variable transmission 61 is connected to the mission case 3 in a state of being located on the left lateral portion on the upper side of the mission case 3. The hydrostatic continuously variable transmission 61 has a neutral stop position, and is configured to be steplessly variable from the neutral stop position to the forward side and the reverse side. The hydrostatic continuously variable transmission 61 has a transmission input shaft 61a and a transmission output shaft 61b that extend to the outside. The power of the engine E is transmitted to the transmission input shaft 61a of the hydrostatic continuously variable transmission 61 through the belt transmission mechanism 61c. A portion of the speed change input shaft 61 a located on the opposite side of the belt transmission mechanism 61 c and the speed change output shaft 61 b are arranged so as to enter the inside of the transmission case 3.

  A hydraulic pump 62 is connected to the right side portion of the mission case 3. The pump input shaft 62 a of the hydraulic pump 62 is disposed so as to enter the inside of the mission case 3. The pump input shaft 62a is arranged concentrically with the speed change input shaft 61a, and is splined so as to rotate integrally with the speed change input shaft 61a by an extension input shaft 61d. As a result, the power of the engine E is transmitted from the transmission input shaft 61a of the hydrostatic continuously variable transmission 61 to the hydraulic pump 62, and the hydraulic pump 62 is driven.

  A first transmission shaft 63 that is rotatably supported inside the transmission case 3 is splined to the transmission output shaft 61b. The first transmission shaft 63 is provided with a first shift gear 64 that rotates integrally with the first transmission shaft 63 and is slidable with respect to the first transmission shaft 63 by a spline structure. . The first shift gear 64 is integrally provided with a first high speed gear 64a and a first low speed gear 64b having a diameter larger than that of the first high speed gear 64a.

  On the lower transmission side of the first transmission shaft 63, a second transmission shaft 65 parallel to the first transmission shaft 63 is supported and provided in the transmission case 3. The second transmission shaft 65 is provided with a large-diameter gear 65 a and a medium-diameter gear 65 b smaller in diameter than the large-diameter gear 65 a fixed to the second transmission shaft 65. By shifting the first shift gear 64, one of the meshing of the first high speed gear 64a and the large diameter gear 65a and the meshing of the first low speed gear 64b and the medium diameter gear 65b is selected. Power can be transmitted from the transmission shaft 63 to the second transmission shaft 65. A small-diameter gear 65c having a smaller diameter than the medium-diameter gear 65b is fixed to the second transmission shaft 65.

  On the lower transmission side of the second transmission shaft 65, a third transmission shaft 67 parallel to the second transmission shaft 65 is supported and provided in the transmission case 3. The third transmission shaft 67 is provided with a second shift gear 68 that rotates integrally with the third transmission shaft 67 and is slidable with respect to the third transmission shaft 67 by a spline structure. . The second shift gear 68 is integrally provided with a second high speed gear 68a and a second low speed gear 68b having a diameter larger than that of the second high speed gear 68a. By shifting the second shift gear 68, either the meshing of the medium diameter gear 65b and the second high speed gear 68a or the meshing of the small diameter gear 65c and the second low speed gear 68b is selected, and the second transmission Power can be transmitted from the shaft 65 to the third transmission shaft 67. A transmission gear 69 is fixed to the third transmission shaft 67. A first bevel gear 70 is fixed to the third transmission shaft 67.

  On the lower transmission side of the third transmission shaft 67, a pair of front transmission shafts 71 are arranged in contact with each other in parallel with the third transmission shaft 67. A differential mechanism 72 is provided between the pair of front transmission shafts 71. A differential case 72 a of the differential mechanism 72 is rotatably supported inside the mission case 3. A transmission gear 69 fixed to the third transmission shaft 67 is meshed with a driven gear 72b fixed to the differential case 72a.

  A differential lock body 72c is externally fitted to one front transmission shaft 71 of the pair of front transmission shafts 71 so as to be integrally rotatable and slidable by a key structure. The differential lock body 72c can be switched between a differential enabled state (diff lock released state) released from the differential case 72a and a differential disabled state (diff locked state) engaged with the differential case 72a. It is configured.

  As shown in FIGS. 2 and 7, the rear portion of the mission case 3 is provided with a travel output shaft 74 that protrudes rearward from the rear end portion of the mission case 3. A second bevel gear 75 is provided at the front end of the travel output shaft 74. The second bevel gear 75 is meshed with the first bevel gear 70 fixed to the third transmission shaft 67, whereby power is transmitted from the third transmission shaft 67 to the travel output shaft 74.

  A rear transmission case 19 that supports the pair of left and right rear wheels 11R is provided, and a rear transmission shaft 77 is interlocked and linked between the travel output shaft 74 and the rear transmission shaft 76 of the rear transmission case 19. . The power transmitted to the rear transmission shaft 76 is transmitted to the left and right rear wheels 11R via the side clutch 73, respectively.

  As a result, the power of the engine E causes the transmission output shaft 61b, the first transmission shaft 63, the second transmission shaft 65, the third transmission shaft 67, the differential mechanism 72, and the front transmission shaft 71 of the hydrostatic continuously variable transmission 61 to be transmitted. Via the differential case 72a of the differential mechanism 72, the travel output shaft 74, and the rear transmission shaft 76, and then transmitted to the pair of left and right rear wheels 11R.

[About work equipment drive system]
Next, the transmission structure to the seedling planting device 2 which is a working device will be described.
As shown in FIG. 8, on the lower transmission side of the second transmission shaft 65, a fourth transmission shaft 80 parallel to the second transmission shaft 65 is supported and provided in the transmission case 3. A work output gear 81 is fixed to the second transmission shaft 65. The power of the second transmission shaft 65 is configured to be transmitted from the work output gear 81 to the fourth transmission shaft 80 via the torque limiter T.

  The fourth transmission shaft 80 is provided with a planting shift gear 84 that rotates integrally with the fourth transmission shaft 80 and is slidable with respect to the fourth transmission shaft 80 by a spline structure. Yes. The planting shift gear 84 is integrally provided with a first planting low speed gear 84a and a first planting high speed gear 84b having a smaller diameter than the first planting low speed gear 84a.

  The first transmission shaft 63 includes a first loose-fitting gear 85a, a second loose-fitting gear 85b, a third loose-fitting gear 85c, a fourth loose-fitting gear 85d, and a fifth loose-fitting gear 85e. On the other hand, it is supported so as to be relatively rotatable. The first loose-fitting gear 85a, the second loose-fitting gear 85b, the third loose-fitting gear 85c, the fourth loose-fitting gear 85d, and the fifth loose-fitting gear 85e are fixed to each other so as to rotate together. The diameters of the gears are set such that the first loose-fit gear 85a, the second loose-fit gear 85b, the third loose-fit gear 85c, the fourth loose-fit gear 85d, and the fifth loose-fit gear 85e increase in order. .

  The planting shift gear 84 is engaged with the first planting low-speed gear 84a and the first loose-fitting gear 85a and the first planting high-speed gear 84b by sliding the second speed change operation rod 27. And meshing with the fifth loose-fitting gear 85e can be selected. Thus, the power transmitted from the planting shift gear 84 to the lower transmission side can be shifted in two stages. As described above, the planting shift gear 84, the second speed change operating rod 27, the first loosely fitted gear 85a, the fifth loosely fitted gear 85e, and the like constitute the second speed change mechanism S2 disposed in the transmission case 3. Yes. That is, the second speed change mechanism S2 shifts the power from the engine E to two stages (an example of “multiple stages”), so that the seedling as “ground work” by the seedling planting device 2 that is the “work apparatus”. Change the planting interval (between stocks) in two stages.

  A fifth transmission shaft 86 parallel to the first transmission shaft 63 is supported in the transmission case 3 on the lower transmission side of the fourth transmission shaft 80 and the first transmission shaft 63. The fifth transmission shaft 86 is provided with a first transmission gear 87a, a second transmission gear 87b, a third transmission gear 87c, and a fourth transmission gear 87d that are supported in a relatively rotatable manner. The diameters of the gears are such that the first transmission gear 87a, the second transmission gear 87b, the third transmission gear 87c, and the fourth transmission gear 87d become smaller in this order. The first transmission gear 87a is always meshed with the first loose gear 85a, the second transmission gear 87b is always meshed with the second loose gear 85b, and the third transmission gear 87c is meshed with the third loose gear 85c. The fourth transmission gear 87d is always meshed with the fourth loosely engaging gear 85d. A third bevel gear 88 is fixed to the fifth transmission shaft 86.

  The fifth transmission shaft 86 is provided by a large-diameter cam portion 26b provided on one end side of the first transmission operation rod 26 by sliding the first transmission operation rod 26 inserted in the center of the fifth transmission shaft 86 in the axial direction. A transmission ball (not shown) engaged with and supported by is pushed outward and displaced in the radial direction. By engaging the transmission ball with the central hole of any one of the first transmission gear 87a, the second transmission gear 87b, the third transmission gear 87c, and the fourth transmission gear 87d, Only one set is selected for meshing transmission, and the power transmitted to the driven fifth transmission shaft 86 can be shifted in four stages. As described above, the first transmission gear 87a, the second transmission gear 87b, the third transmission gear 87c, the fourth transmission gear 87d, the first speed change operation rod 26, the transmission ball, and the like are arranged in the mission case 3. A transmission mechanism S1 is configured. In other words, the first speed change mechanism S1 shifts the power from the engine E to four stages (an example of “multiple stages”), so that the seedling as “ground work” by the seedling planting device 2 that is the “work apparatus”. Change the planting interval (between stocks) to 4 levels.

  As described above, the power of the planting system is changed to a total of eight speeds by combining the four speeds by the operation of the first speed change operation rod 26 and the two speeds by the operation of the second speed change rod 27. It is configured to be able to do.

On the rear side of the mission case 3, a cylindrical body 90 that is supported so as to be rotatable relative to the mission case 3 is provided. The cylindrical body 90 is provided with a fourth bevel gear 91.
The fourth bevel gear 91 is meshed with a third bevel gear 88 fixed to the fifth transmission shaft 86.

  At the rear part of the mission case 3, a planting output shaft 92 that protrudes rearward from the rear end part of the mission case 3 and that is concentrically with the cylindrical body 90 and is located inside the cylindrical body 90 is provided. A planting clutch 93 that rotates integrally with the planting output shaft 92 and is slidable with respect to the planting output shaft 92 is externally fitted to the planting output shaft 92 by a spline structure. . The planting clutch 93 can be switched between an engagement state in which the planting clutch 93 is engaged and a disengagement state in which the planting clutch 93 is not engaged with the cylinder 90. When the planting clutch 93 is engaged, the power of the fifth transmission shaft 86 is transmitted to the planting output shaft 92 via the third bevel gear 88, the fourth bevel gear 91, the cylindrical body 90, and the planting clutch 93. Communicated. On the other hand, when the planting clutch 93 is disengaged, power transmission from the fifth transmission shaft 86 to the planting output shaft 92 can be cut off. The planting clutch 93 is urged toward the engaged state, and by switching the operation shaft 94 supported by the bush 95, the planted clutch 93 is switched between the engaged state and the disengaged state. It is configured.

  As shown in FIG. 8, the power of the planting output shaft 92 is transmitted to the input shaft 98 of the feed case 97 via the rotation transmission shaft 96. By the power input to the input shaft 98, the seedling raising table 20 is reciprocated in conjunction with the driving of the planting arm 23 and the seedling planting operation of the planting arm 23. Thus, seedlings are planted on the farm surface at a planting speed that is shifted by the first transmission mechanism S1 and the second transmission mechanism S2 in accordance with the traveling speed of the machine body. Thereby, rice planting can be performed at a desired planting interval (between plants) by operating the first transmission mechanism S1 and the second transmission mechanism S2.

[Mission case structure]
The internal structure of the mission case 3 is shown in FIGS.
The mission case 3 is a divided case body composed of a box-shaped case main body 30 having an opening 30a on one end side in the left-right direction and a lid-like case 31 provided so as to close the opening 30a. It is comprised by the combination of. The case main body 30 and the lid-like case 31 are made of aluminum die cast, and are integrated by bolting the lid-like case 31 so as to face the opening 30a of the case main body 30.
As shown in FIGS. 4 and 6, the case body 30 includes a front wall 30 f that forms the front surface of the box-shaped mission case 3 in the aircraft traveling direction, a rear wall 30 r that forms the rear surface of the mission case 3, An upper wall 30t constituting the upper surface of the mission case 3, a bottom wall 30b constituting the bottom surface of the mission case 3, and a lateral wall 30s constituting the left side surface of the mission case 3 are provided. The lid-like case portion 31 constitutes the right side surface of the mission case 3, and the mission case 3 is formed in a substantially rectangular box shape as a whole.

As shown in FIGS. 2 to 4, the hydraulic torque generator 4 as a power steering device is mounted on the upper surface of the transmission case 3 in a slightly tilted posture at the front position of the upper wall 30 t of the case body 30. Has been. From the torque generator 4, the steering operation shaft 15 a extends obliquely rearward and upward. From the lower side of the torque generator 4, an output shaft 4 a that is coaxial with the steering operation shaft 15 a and faces downward is arranged so as to enter the mission case 3.
A steering shaft 41 is connected to the lower end side of the output shaft 4a coaxially with the output shaft 4a and the steering operation shaft 15a via a joint 40 having a spline portion on the inner peripheral side. That is, a spline is formed on the outer periphery of the upper end portion 41 a of the steering shaft 41 and is engaged with the spline on the inner peripheral side of the joint 40.

As shown in FIGS. 4 to 6, a bottom opening 32 for inserting / removing the steering shaft 41 is formed at a front position on the bottom wall 30 b side of the case main body 30 of the transmission case 3.
The bottom opening 32 is formed so that the steering shaft 41 can be inserted / removed from the lower side of the transmission case 3, and a lower bearing 43 d (lower first 1) for pivotally supporting the lower end side of the steering shaft 41. It is also used as a mounting portion corresponding to a bearing portion.
In the steering shaft 41, a pinion gear 42 is integrally formed near the lower end opposite to the upper end portion 41a, and the lower bearing 43d is a shaft portion that extends downward from a position where the pinion gear 42 of the steering shaft 41 exists. And is fitted into the bottom opening 32.

The bottom wall 30b of the case main body 30 of the mission case 3 rotates integrally with the pitman arm 44 at a position farther rearward than the position where the bottom opening 32 for inserting and removing the steering shaft 41 is formed. Another bottom opening 33 for mounting the arm support shaft 45 provided in this manner is formed. The other bottom opening 33 is also used as a mounting portion for a lower bearing 48d (corresponding to a lower second bearing portion) for pivotally supporting the arm support shaft 45.
A spline that engages with a spline formed on the inner peripheral side of the sect gear 46 (corresponding to the steering gear) is provided on the outer peripheral surface above the portion pivotally supported by the lower bearing 48d of the arm support shaft 45. The sect gear 46 is formed so that it can be inserted into and removed from the arm support shaft 45 and is integrally rotated.

The sect gear 46 meshes with the pinion gear 42 of the steering shaft 41, and the sect gear 46 is rotated as the steering shaft 41 rotates. As the sect gear 46 rotates, the pitman arm 44 swings within a predetermined angle range via the arm support shaft 45.
The tie rod 47 connected to the free end portion of the pitman arm 44 is interlocked and connected to a knuckle arm (not shown) so that the left and right front wheels 11F and 11F are steered according to the swing operation amount of the pitman arm 44. It is configured.

As shown in FIGS. 4 and 5, the steering shaft 41 has an upper bearing 43 u (upper first shaft 43) not only on the shaft portion extending downward from the position where the pinion gear 42 exists but also on the upper side of the pinion gear 42. It corresponds to one bearing part).
As shown in FIGS. 4 to 6, the upper bearing 43 u is attached to the shaft side attachment portion 34 that extends horizontally from the front wall 30 f and the lateral wall 30 s of the mission case 3 in the mission case 3. Yes.
As shown in FIG. 5, the shaft side mounting portion 34 has a recess 34a in which the upper bearing 43u can be fitted from below on the lower surface side, and the steering shaft 41 is pivoted by fitting the upper bearing 43u from below. It is configured to support.

The outer diameters of the upper bearing 43u and the lower bearing 43d are slightly smaller than the inner diameter D3 of the bottom opening 32, can be fitted with appropriate fitting tolerances, and can be inserted / removed through the bottom opening 32 of the mission case 3. It is configured. Further, the inner diameters of the upper bearing 43u and the lower bearing 43d are slightly larger than the outer diameter D1 of the steering shaft 41, are fitted with appropriate fitting tolerances, and are larger than the outer diameter D2 of the pinion gear 42. It is set small.
The upper bearing 43u and the lower bearing 43d are in contact with the upper and lower edges of the pinion gear 42 so that the pinion gear 42 is sandwiched vertically, and the upper bearing 43u is fitted into the recess 34a, and the lower bearing 43d is opened at the bottom. In 32, the retaining ring 32a holds the retaining state.

As shown in FIGS. 4 and 5, the arm support shaft 45 is not limited to the shaft portion positioned below the position where the sect gear 46 exists, but also on the upper side of the sect gear 46, the upper bearing 48 u (upper second bearing). Is equivalent to the department).
As shown in FIGS. 4 to 6, the upper bearing 48 u is attached to the arm-side attachment portion 36 that extends from the lateral wall 30 s of the mission case 3 in the horizontal direction inside the mission case 3.
As shown in FIG. 5, the arm side mounting portion 36 is formed with a recess 36a into which the upper bearing 48u can be inserted from below on the lower surface side, and the arm bearing shaft 45 can be fitted by inserting the upper bearing 48u from below. It is configured to pivot.

The outer diameters of the upper bearing 48u and the lower bearing 48d are slightly smaller than the inner diameter D6 of the bottom opening 33, can be fitted with an appropriate fit tolerance, and can be inserted / removed through the bottom opening 33 of the mission case 3. It is configured.
Further, the inner diameter of the lower bearing 48d is slightly larger than the outer diameter D5 of the spline portion of the arm support shaft 45 and is fitted with an appropriate fit tolerance. The shaft 45 is slightly larger in diameter than the outer diameter D4 in the shaft portion above the spline portion of the support shaft 45, and is fitted with an appropriate fit tolerance.
The upper bearing 48u and the lower bearing 48d are in contact with the upper and lower edges of the sect gear 46, and the upper bearing 48u is fitted into the recess 36a with the sect gear 46 sandwiched vertically, and the lower bearing 48d is opened at the bottom. In 33, the retaining ring 33a holds the retaining state.

As shown in FIGS. 4 to 6, the shaft-side attachment portion 34 and the arm-side attachment portion 36 are integrated with each other by an intermediate connection portion 35 that is located between the shaft-side attachment portion 34 and the arm-side attachment portion 36. It is connected. Since the intermediate connecting portion 35 is formed in a rib shape from the inner surface of the left lateral wall 30s of the case main body portion 30 and is not formed with a concave portion for attaching a bearing or the like, the thickness in the vertical direction is as shown in the figure. It is thinner than the shaft-side mounting portion 34 and the arm-side mounting portion 36, and is formed so as to protrude less from the left lateral wall 30 s than the shaft-side mounting portion 34 and the arm-side mounting portion 36 in plan view.
That is, the shaft-side mounting portion 34 to which the upper bearing 43u that supports the steering shaft 41 is mounted and the arm-side mounting portion 36 to which the upper bearing 48u that supports the arm support shaft 45 is mounted are positioned in the vertical direction with respect to the intermediate connection portion 35. And is formed wider in the horizontal direction than in the intermediate connection portion 35 even in the horizontal direction.
The intermediate connection portion 35 has a smaller thickness and a smaller area than the shaft side attachment portion 34 and the arm side attachment portion 36, but the mission can be achieved by connecting the shaft side attachment portion 34 and the arm side attachment portion 36. While avoiding an increase in the weight of the case 3 as much as possible, the strength of the shaft side mounting portion 34 and the arm side mounting portion 36 can be effectively increased.

A vertical rib 37 is integrally formed on the arm side mounting portion 36 over the upper surface of the arm side mounting portion 36 and the left horizontal wall 30 s of the case main body portion 30 of the transmission case 3. The vertical rib 37 has a vertical plate surface parallel to the axis of the arm spindle 45 supported by the arm side mounting portion 36, and reinforces the vertical load acting on the arm side mounting portion 36. It is provided so that it can be performed effectively.
The vertical ribs 37 are provided on the front and rear sides of the upper bearing 48 u that pivotally supports the arm support shaft 45. Of the front and rear vertical ribs 37, the vertical ribs 37 b farther from the steering shaft 41 are formed larger than the vertical ribs 37 a closer to the steering shaft 41.
Moreover, both the vertical ribs 37a and 37b are connected to each other by a horizontal rib 38 along the horizontal direction, and are configured to further increase the rigidity.

[Other Embodiment 1]
In the above embodiment, the operation of the steering handle 15 is transmitted to the torque generator 4 via the steering operation shaft 15a, and the output of the torque generator 4 is transmitted to the pitman arm 44 via the steering shaft 41. Although the thing was illustrated, it is not restricted to such a structure.
For example, the torque generator 4 is omitted, and the operation of the steering handle 15 is directly transmitted to the steering shaft 41, and the pitman arm 44 is operated in accordance with the operation of the steering shaft 41. May be.
Other configurations may be the same as those in the above-described embodiment.

[Second embodiment]
In the above-described embodiment, the transmission case 3 has a structure in which the split surface is constituted by the split case body of the case main body portion 30 and the lid-like case portion 31 that are divided in the left and right directions along the vertical direction. However, it is not limited to this structure. For example, it may have a structure in which the split surface is divided along the top and bottom in the left-right direction and divided into front and back, or the split surface is divided in the top and bottom along the horizontal direction.
Other configurations may be the same as those in the above-described embodiment.

  The work vehicle to which the present invention is applied is not limited to a riding type rice transplanter, and may be other paddy working machines such as a walking type rice transplanting machine, a riding type direct seeding machine, and a walking type direct seeding machine. Not only a machine but various farming machines such as a tractor, a lawnmower, a transporter, etc. may be used.

3 Mission Case 4 Power Steering Device 4a Output Shaft 30 Case Main Body 31 Lid Case 30b Bottom Wall 30f Front Wall 30s Horizontal Wall 32 Bottom Opening 34 Shaft Side Attachment 35 Intermediate Connection 36 Arm Side Attachment 37 Vertical Rib 37a Near Side Vertical rib 37b Vertical rib 38 Far side rib 41 Steering shaft 42 Pinion gear 43d Lower first bearing portion 43u Upper first bearing portion 44 Pitman arm 45 Arm spindle 46 Steering gear 48u Upper second bearing portion D2 Outer diameter D3 Inner diameter

Claims (14)

A steering shaft arranged with the lower end side inserted into the transmission case;
A pitman arm deployed under the mission case;
An arm support shaft disposed at the bottom of the transmission case so as to swing the pitman arm,
A pinion gear provided in a lower part of the steering shaft in the transmission case;
In the transmission case, the steering gear provided on the arm support shaft is engaged with the steering shaft, and the steering shaft and the arm support shaft are connected to each other.
An upper and lower portion sandwiching the pinion gear by a lower first bearing portion provided below the pinion gear and an upper first bearing portion provided above the pinion gear in the lower portion of the space inside the transmission case. Supported in both positions ,
The upper first bearing portion is supported by a shaft side mounting portion extending from a case wall of the mission case, and the shaft side mounting portion is formed across the front wall and the lateral wall of the mission case,
The arm support shaft is pivotally supported by an upper second bearing portion provided above the steering gear, and the upper second bearing portion is supported by an arm side mounting portion provided on a lateral wall of the transmission case, The shaft side mounting portion and the arm side mounting portion extending from the case wall of the transmission case are integrally connected to each other by an intermediate connection portion located between the shaft side mounting portion and the arm side mounting portion. The intermediate connection portion is a work vehicle that is formed in a rib shape so as to protrude from the inner surface of the lateral wall of the transmission case . The transmission case includes a box-shaped case main body having an opening formed at one end side in the left-right direction, and a lid-shaped case that closes the opening, and is configured to be openable and closable. The work vehicle according to claim 1 , wherein the work body is provided on the case body. The work vehicle according to claim 1 or 2 , wherein a bottom opening for inserting and removing the steering shaft is formed in a bottom wall of the transmission case, and the lower first bearing portion is provided in the bottom opening. The lower first bearing portion is configured to be detachable from the lower side with respect to the bottom opening, and an inner diameter of the lower first bearing portion is smaller than an outer diameter of the pinion gear, and an outer diameter of the lower first bearing portion. The work vehicle according to claim 3, wherein is formed larger than an outer diameter of the pinion gear. The work vehicle according to claim 3 or 4, wherein the upper first bearing portion is formed such that an outer diameter thereof is smaller than an inner diameter of the bottom opening. The shaft side mounting portion, the arm side mounting portion, and the intermediate connection portion are configured to form a bearing mounting portion, and the bearing mounting portion includes the shaft side mounting portion corresponding to the periphery of the steering shaft and the shaft side mounting portion. The work vehicle according to any one of claims 1 to 5, wherein the arm-side attachment portion corresponding to the periphery of the arm spindle is formed wider in the left-right direction in plan view than the intermediate connection portion. The work vehicle according to any one of claims 1 to 6 , wherein an upper end side of the steering shaft is connected to an output shaft of a power steering device provided on the upper side of the transmission case. The work vehicle according to claim 1, wherein the arm-side mounting portion is formed with vertical ribs for reinforcement against a load in a vertical direction. The work vehicle according to claim 8 , wherein the vertical rib is formed across an upper surface of the arm-side mounting portion and a lateral wall of the transmission case. The upper first bearing portion located close to the upper side of the pinion gear is supported by a shaft side mounting portion formed across the front wall and the lateral wall of the transmission case,
The said arm side attachment portion and its shaft-side mounting portion, the integrally coupled with, claim 8 or 9, wherein one another by an intermediate connecting portion located between said shaft-side mounting portion and the arm side attachment portion Work vehicle. The work vehicle according to any one of claims 8 to 10 , wherein the vertical ribs are formed at both front and rear positions of the upper second bearing portion. 12. The work vehicle according to claim 11 , wherein the vertical rib is formed such that a vertical rib on a side farther from the steering shaft is larger than a vertical rib on a side close to the steering shaft. The work vehicle according to claim 11 or 12 , wherein the vertical ribs are connected to each other by a horizontal rib along a horizontal direction. The vertical ribs are formed on both front and rear sides of the upper second bearing portion over the upper surface of the arm side mounting portion and the lateral wall of the transmission case,
The upper first bearing portion located close to the upper side of the pinion gear is supported by a shaft side mounting portion formed across the front wall and the lateral wall of the transmission case, and the shaft side mounting portion and the arm side mounting portion Are integrally connected to each other by an intermediate connecting portion located between the shaft side mounting portion and the arm side mounting portion,
The vertical rib on the side far from the steering shaft is formed larger than the vertical rib on the side close to the steering shaft,
The work vehicle according to claim 8 , wherein the vertical ribs are connected to each other by a horizontal rib along the horizontal direction.

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