CN105984493B - Riding rice transplanter or riding direct seeder - Google Patents

Abstract

A riding rice transplanter or a riding direct seeder is provided with an arm support shaft (45) arranged at the bottom of a transmission case (3), the arm support shaft swings a connecting lever arm (44), a pinion (42) arranged at the lower part of a steering shaft (41) in the transmission case (3) is meshed with a steering gear (46) arranged at the arm support shaft (45) in the transmission case (3), so that the rotating shaft (41) and the arm support shaft (45) are linked, the steering shaft (41) is supported at two positions of the upper part and the lower part clamping the pinion (42) through a lower part 1 bearing part (43d) and an upper part 1 bearing part (43u), the lower part 1 bearing part (43d) is arranged at the lower side of the pinion (42), and the upper part 1 bearing part (43u) is arranged at the upper side of the pinion (42) at the lower part of the space in the transmission case (3). The durability of the power transmission structure between the steering shaft and the connecting rod arm can be improved.

Description

Riding rice transplanter or riding direct seeder

Technical Field

The present invention relates to a riding rice transplanter or a riding direct seeder, which comprises a steering shaft and a connecting lever arm, wherein the steering shaft is supported in a state that the lower end side of the steering shaft is inserted into a gear box; a connecting lever arm is provided on the lower side of the gearbox.

Background

As described above, the following technique [1] is known as a work vehicle in which a steering shaft and a link arm are supported in a 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 portion of the transmission case, and the lower end side of the steering shaft is supported by a ball bearing provided on the bottom wall of the transmission case.

The pinion gear of the steering shaft is engaged with the sector gear of the rotary shaft that rotates integrally with the link arm at a position slightly above the portion supported by the ball bearing. The rotation of the steering shaft is transmitted to the link arm by the engagement of the pinion gear with the sector gear (see patent document 1).

In this work vehicle, the lower end side of the arm support shaft that rotates integrally with the link arm is supported by a ball bearing provided on the bottom wall of the transmission case, and the upper end side of the arm support shaft is supported by a ball bearing on a support portion extending from the lateral side wall of the transmission case above the sector gear (see patent document 1).

Patent document 1: japanese patent laid-open No. 2007-325528 (paragraphs "0043 and 0044", FIGS. 8 and 9)

In the work vehicle described in patent document 1, the lower end side of the steering shaft is accurately supported by the ball bearing.

However, on the upper end side, the distance from the meshing position of the pinion and the sector gear to the support portion on the upper end side becomes long, and the spline shaft may be slightly deflected. Alternatively, the steering shaft is supported by the output shaft of the torque generator through a detachable coupling structure such as spline fitting, and the spline shaft may be slightly inclined because of backlash in the supporting structure portion.

If the spline shaft is slightly inclined from the upper side to the lower side due to the deflection or looseness of the spline shaft, uneven wear may easily occur in the pinion and the sector gear at the meshing portion between the pinion and the sector gear, which may cause a reduction in durability.

In the work vehicle described in patent document 1, the lower end side and the upper end side of the arm support shaft that rotates integrally with the link arm are supported by ball bearings, and therefore, the work vehicle is useful in that the arm support shaft can be supported with good stability. However, in this structure, since the support portion of the ball bearing that supports the upper end side of the arm support shaft is configured to extend from the lateral side wall of the transmission case, the arm support shaft may be knocked in from below when the arm support shaft is attached from the bottom side of the transmission case. In this case, since a large impact load acts on the support portion of the ball bearing projecting from the lateral side wall of the transmission, there is a tendency to increase the weight of the transmission in order to increase the strength of the support portion, which leaves room for improvement.

Disclosure of Invention

Problems to be solved by the invention

The invention aims to provide a riding rice transplanter or a riding direct seeder, which can improve the durability of a power transmission structure between a steering shaft and a connecting rod arm.

The invention can improve the supporting strength of the upper end side supporting part of the arm fulcrum shaft of the connecting lever arm while avoiding the increase of the weight of the gear box.

Means for solving the problems

[ solution 1]

In order to achieve the above object, a riding rice transplanter or a riding direct seeder according to the present invention includes: a steering shaft disposed with a lower end side thereof inserted into the transmission case; a link lever arm provided at a lower side of the transmission case; and an arm support shaft that is disposed at a bottom of the transmission case and that swings the link arm, wherein the steering shaft and the arm support shaft are interlocked by meshing a pinion gear provided at a lower portion of the steering shaft in the transmission case and a steering gear provided at the arm support shaft in the transmission case, and the steering shaft is supported at two positions, i.e., upper and lower positions, on both sides of the pinion gear by a lower 1 st bearing portion and an upper 1 st bearing portion, the lower 1 st bearing portion being provided at a lower portion of the pinion gear, and the upper 1 st bearing portion being provided at an upper portion of the pinion gear in a lower portion of a space in the transmission case.

[ action and Effect of claim 1]

According to the structure of claim 1, the steering shaft is supported by the lower 1 st bearing portion provided on the lower side of the pinion and the upper 1 st bearing portion provided on the upper side of the pinion at the lower portion of the space in the transmission case. That is, the steering shaft is supported at two positions, upper and lower, in the lower portion of the space in the transmission case with the pinion interposed therebetween. Thus, the steering shaft is in a state in which its horizontal position is restricted at two upper and lower positions close to the meshing position between the pinion gear and the sector gear.

Therefore, the possibility of deflection occurring in the steering shaft due to a load or the like generated at the meshing portion with the sector gear is reduced, and the position of the pinion is accurately maintained even in a support structure in which the upper portion of the steering shaft is largely or hardly loosened. This reduces the possibility of uneven wear of the pinion and the sector gear, and has the advantage that the durability of the power transmission structure between the steering shaft and the link arm can be improved.

[ solution 2]

In another aspect of the present invention to achieve the above object, the upper 1 st bearing portion is supported by an axle-side mounting portion extending from a wall of the transmission case.

[ action and Effect of claim 2]

According to the structure of claim 2, since the upper-stage 1 bearing portion is supported by the shaft-side mounting portion extending from the wall of the transmission case, the steering shaft can be firmly supported at two positions, i.e., the upper and lower positions sandwiching the pinion gear, by effectively utilizing the strength of the wall of the transmission case itself.

Therefore, the support structure of the upper 1 st bearing portion can be firmly configured with a simple structure.

[ solution 3]

In another aspect of the present invention to achieve the above object, the shaft-side mounting portion is formed across a front wall and a lateral wall of the transmission case.

[ action and Effect of claim 3]

According to the structure of claim 3, since the shaft-side mounting portion projecting from the wall of the transmission case is formed across the front wall and the lateral wall of the transmission case, there is an advantage that the mounting strength of the shaft-side mounting portion to the wall is easily and firmly secured with a simple structure.

[ solution 4]

In another aspect of the present invention to achieve the above object, the transmission case is configured to be openable and closable, and includes a case-shaped case body portion having an opening portion formed at one end side in a left-right direction, and a lid-shaped case portion closing the opening portion, and the shaft-side mounting portion is provided in the case body portion.

[ action and Effect of claim 4]

According to the structure of claim 4, since the shaft-side mounting portion is provided not in the lid-like box portion but in the box-like box main body, the shaft-side mounting portion itself can be easily formed large, and the shaft-side mounting portion can be provided to function as a reinforcing rib of the box-like box main body. Therefore, the transmission having the shaft-side mounting portion is advantageously easily constructed with a simple structure.

[ solution 5]

In another aspect of the present invention to achieve the above object, a bottom opening for inserting and removing the steering shaft is formed in a bottom wall of the transmission case, and the lower 1 st bearing portion is provided in the bottom opening.

[ action and Effect of claim 5]

According to the structure of claim 5, the bottom opening for inserting and removing the steering shaft is used as the mounting portion of the lower 1 st bearing portion, so that the mounting structure of the lower 1 st bearing portion can be simplified.

[ solution 6]

In another aspect of the present invention to achieve the above object, the lower 1 st bearing portion is configured to be detachable from the bottom opening from a lower side, an inner diameter of the lower 1 st bearing portion is formed smaller than an outer diameter of the pinion gear, and an outer diameter of the lower 1 st bearing portion is formed larger than the outer diameter of the pinion gear.

[ action and Effect of claim 6]

According to the structure of claim 6, since the inner diameter of the lower 1 st bearing portion is formed smaller than the outer diameter of the pinion gear and the outer diameter of the lower 1 st bearing portion is formed larger than the outer diameter of the pinion gear, the lower 1 st bearing portion can be used to prevent the pinion gear from coming off downward, and the steering shaft can be attached and detached together with the pinion gear by detaching the lower 1 st bearing portion.

Therefore, the steering shaft and the pinion can be easily attached and detached.

[ solution 7]

In another aspect of the present invention to achieve the above object, the upper 1 st bearing portion is formed such that an outer diameter of the upper 1 st bearing portion is smaller than an inner diameter of the bottom opening.

[ action and Effect of claim 7]

According to the structure of claim 7, the upper 1 st bearing portion can be attached to and detached from the bottom opening by detaching the lower 1 st bearing portion.

Therefore, the bearing portions can be mounted in advance on both the upper and lower sides of the pinion gear of the steering shaft, and the steering shaft can be attached and detached from the bottom opening in this state, which has an advantage that the attachment and detachment operation of the steering shaft and the upper and lower bearing portions can be easily performed.

[ solution 8]

In another aspect of the present invention to achieve the above object, the arm support shaft is pivotally supported by an upper 2 nd bearing portion provided on an upper side of the steering gear, and the upper 2 nd bearing portion is supported by an arm side mounting portion provided on a lateral wall of the transmission case.

[ action and Effect of claim 8]

According to the structure of claim 8, since the upper 2 nd bearing portion is supported by the arm-side mounting portion provided on the lateral wall of the transmission case, the arm support shaft disposed at the bottom of the transmission case can be firmly supported by effectively utilizing the strength of the wall of the transmission case itself. Therefore, the support structure of the upper 2 nd bearing portion is advantageously configured to be strong with a simple structure.

[ solution 9]

In another aspect of the present invention to achieve the above object, the shaft-side mounting portion and the arm-side mounting portion that protrude from the wall of the transmission case are integrally connected to each other by an intermediate connecting portion that is located between the shaft-side mounting portion and the arm-side mounting portion.

[ action and Effect of claim 9]

According to the structure of claim 9, the shaft-side mounting portion and the arm-side mounting portion are integrally connected by the intermediate connecting portion, and therefore, there is an advantage that the support strength of the steering shaft supported by the shaft-side mounting portion and the arm support shaft supported by the arm-side mounting portion can be further improved.

[ solution 10]

In another aspect of the present invention to achieve the above object, the intermediate connecting portion is formed to protrude from an inner surface of the lateral wall of the transmission case in a rib shape.

[ action and Effect of claim 10]

According to the structure of claim 10, there is an advantage that the intermediate connection portion can be easily configured by using the rib-like member formed to protrude from the inner surface of the lateral wall of the transmission case.

[ solution 11]

In another aspect of the present invention to achieve the above object, the shaft-side mounting portion, the arm-side mounting portion, and the intermediate connecting portion constitute a bearing mounting portion, and the shaft-side mounting portion corresponding to the steering shaft periphery and the arm-side mounting portion corresponding to the arm support shaft periphery of the bearing mounting portion are formed to be wider in the left-right direction than the intermediate connecting portion in a plan view.

[ action and Effect of claim 11]

According to the structure of claim 11, since the width in the lateral direction in plan view of the axle-side mounting portion and the arm-side mounting portion that support the steering axle and the arm support shaft is wider than the width in the lateral direction of the intermediate connecting portion, the intermediate connecting portion having a short protruding length in the lateral direction is compact as a whole, and the supporting strength against the load in the vertical direction is easily and firmly maintained because the protruding length is short.

Therefore, there are advantages in that: the intermediate connecting portion having a short protruding length from the wall of the transmission case can firmly support not only the front and rear shaft-side mounting portions and the arm-side mounting portion in the front and rear direction but also in the up and down direction.

[ solution 12]

In another aspect of the present invention to achieve the above object, an upper end side of the steering shaft is coupled to an output shaft of a power steering device provided above the transmission case.

[ action and Effect of claim 12]

The structure according to claim 12 has the following advantages: the support of the steering shaft with respect to the output shaft of the power steering apparatus can be stably performed regardless of whether there is a large or small looseness or the like in the coupling portion of the steering shaft.

[ solution 13]

Another aspect of the present invention for achieving the above object is to provide: a steering shaft disposed with a lower end side thereof inserted into the transmission case; a link lever arm provided at a lower side of the transmission case; and an arm support shaft disposed at a bottom of the transmission case and configured to swing the link arm, wherein the steering shaft is interlocked with the arm support shaft by meshing a pinion gear provided at a lower portion of the steering shaft in the transmission case with a steering gear provided at the arm support shaft in the transmission case, and the steering shaft is supported at two positions, one above the other, on both sides of the pinion gear by a lower 1 st bearing portion and an upper 1 st bearing portion, the lower 1 st bearing portion being provided at a lower portion of the pinion gear, the upper 1 st bearing portion being provided at an upper portion of the pinion gear at a lower portion of a space in the transmission case, the upper 1 st bearing portion being supported by a shaft-side mounting portion protruding from a case wall of the transmission case, a bottom opening for inserting and removing the steering shaft being formed at a bottom wall of the transmission case, the bottom opening is provided with the lower 1 st bearing portion, the lower 1 st bearing portion is configured to be detachable from the bottom opening from a lower side, an inner diameter of the lower 1 st bearing portion is formed smaller than an outer diameter of the pinion gear, an outer diameter of the lower 1 st bearing portion is formed larger than the outer diameter of the pinion gear, and the upper 1 st bearing portion is formed such that the outer diameter of the upper 1 st bearing portion is smaller than the bottom opening.

[ action and Effect of claim 13]

With the configuration of claim 13, the same actions and effects as those of claims 1, 2, 5, 6, and 7 can be obtained.

[ solution 14]

Another aspect of the present invention for achieving the above object is to provide: a steering shaft disposed with a lower end side thereof inserted into the transmission case; a link lever arm provided at a lower side of the transmission case; and an arm support shaft disposed at a bottom of the transmission case and configured to swing the link arm, wherein the steering shaft is interlocked with the arm support shaft by meshing a pinion gear provided at a lower portion of the steering shaft in the transmission case with a steering gear provided at the arm support shaft in the transmission case, and the steering shaft is supported at two positions of upper and lower sides sandwiching the pinion gear by a lower 1 st bearing portion and an upper 1 st bearing portion, the lower 1 st bearing portion being provided at a lower side of the pinion gear, the upper 1 st bearing portion being provided at an upper side of the pinion gear at a lower portion of a space in the transmission case, the upper 1 st bearing portion being supported by a shaft-side mounting portion formed across a front wall and a lateral wall of the transmission case, the arm support shaft being pivotally supported by an upper 2 nd bearing portion provided at an upper side of the steering gear, the upper 2 nd bearing portion is supported by an arm-side mounting portion provided on a 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.

[ action and Effect of claim 14]

With the configuration of claim 14, the same actions and effects as those of claims 1, 2, 3, 8, and 9 can be obtained.

[ solution 15]

Another aspect of the present invention for achieving the above object is to provide: a steering shaft disposed with a lower end side thereof inserted into the transmission case; a link lever arm provided at a lower side of the transmission case; and an arm support shaft disposed at a bottom of the transmission case and configured to swing the link arm, wherein the steering shaft is interlocked with the arm support shaft by meshing a pinion gear provided at a lower portion of the steering shaft in the transmission case with a steering gear provided at the arm support shaft in the transmission case, and the steering shaft is supported at two positions, up and down, sandwiching the pinion gear by a lower 1 st bearing portion and an upper 1 st bearing portion, the lower 1 st bearing portion being provided at a lower portion of the pinion gear, the upper 1 st bearing portion being provided at an upper portion of the pinion gear at a lower portion of a space in the transmission case, the transmission case being configured to be openable and closable, and including a case main body portion having a box shape with an opening portion formed at one end side in a left-right direction, and a lid-like case portion closing the opening portion, the upper 1 st bearing portion is supported by an axle-side mounting portion formed across the front wall and the lateral wall of the tank body, the arm support shaft is pivotally supported by an upper 2 nd bearing portion provided on the upper side of the steering gear, the upper 2 nd bearing portion is supported by an arm-side mounting portion provided on the lateral wall of the tank body, the axle-side mounting portion and the arm-side mounting portion are integrally connected to each other by an intermediate connecting portion, and the intermediate connecting portion is located between the axle-side mounting portion and the arm-side mounting portion.

[ action and Effect of claim 15]

With the configuration of claim 15, the same actions and effects as those of claims 1, 2, 3, 4, 8, and 9 can be obtained.

[ solution 16]

Another aspect of the present invention for achieving the above object is to provide: a steering shaft disposed with a lower end side thereof inserted into the transmission case; a link lever arm provided at a lower side of the transmission case; and an arm support shaft disposed at a bottom of the transmission case and configured to swing the link arm, wherein the steering shaft is interlocked with the arm support shaft by meshing a pinion gear provided at a lower portion of the steering shaft in the transmission case with a steering gear provided at the arm support shaft in the transmission case, and the steering shaft is supported at two positions of upper and lower sides sandwiching the pinion gear by a lower 1 st bearing portion and an upper 1 st bearing portion, the lower 1 st bearing portion being provided at a lower side of the pinion gear, the upper 1 st bearing portion being provided at an upper side of the pinion gear at a lower portion of a space in the transmission case, the upper 1 st bearing portion being supported by a shaft-side mounting portion formed across a front wall and a lateral wall of the transmission case, the arm support shaft being pivotally supported by an upper 2 nd bearing portion provided at an upper side of the steering gear, the upper 2 nd 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 are integrally connected to each other by an intermediate connecting portion, the intermediate connecting portion is located between the shaft-side mounting portion and the arm-side mounting portion, the intermediate connecting portion protrudes from an inner surface of the lateral wall of the transmission case and is formed in a rib shape, the shaft-side mounting portion, the arm-side mounting portion and the intermediate connecting portion constitute a bearing mounting portion, and the bearing mounting portion corresponds to the shaft-side mounting portion around the steering shaft and corresponds to the arm-side mounting portion around the arm support shaft and is formed in a width in a left-right direction in a plan view as compared with the intermediate connecting portion.

[ action and Effect of claim 16]

With the configuration of claim 16, the same actions and effects as those of claims 1, 2, 3, 8, 9, 10, and 11 can be obtained.

[ solution 17]

Another aspect of the present invention for achieving the above object is to provide: a steering shaft disposed with a lower end side thereof inserted into the transmission case; a link lever arm provided at a lower side of the transmission case; and an arm support shaft disposed at a bottom of the transmission case and configured to swing the link arm, wherein the steering shaft is interlocked with the arm support shaft by meshing a pinion gear provided at a lower portion of the steering shaft in the transmission case with a steering gear provided at the arm support shaft in the transmission case, and the steering shaft is supported at two positions, up and down, sandwiching the pinion gear by a lower 1 st bearing portion and an upper 1 st bearing portion, the lower 1 st bearing portion being provided at a lower portion of the pinion gear, the upper 1 st bearing portion being provided at an upper portion of the pinion gear at a lower portion of a space in the transmission case, the transmission case being configured to be openable and closable, and including a case main body portion having a box shape with an opening portion formed at one end side in a left-right direction, and a lid-like case portion closing the opening portion, the upper 1 st bearing portion is supported by an axle-side mounting portion formed across a front wall and a lateral wall of the case main body, the arm support shaft is pivotally supported by an upper 2 nd bearing portion provided on an upper side of the steering gear, the upper 2 nd bearing portion is supported by an arm-side mounting portion provided on a lateral wall of the case main body, the axle-side mounting portion and the arm-side mounting portion are integrally connected to each other by an intermediate connecting portion located between the axle-side mounting portion and the arm-side mounting portion, the intermediate connecting portion is formed in a rib-like shape protruding from an inner surface of the lateral wall of the transmission case, and a bearing mounting portion is constituted by the axle-side mounting portion, the arm-side mounting portion and the intermediate connecting portion, the bearing mounting portion corresponding to the axle-side mounting portion around the steering shaft and the arm-side mounting portion corresponding to the arm support shaft around the steering shaft, the intermediate connection portion is formed to be wider in the left-right direction in plan view than the intermediate connection portion.

[ action and Effect of claim 17]

With the configuration of claim 17, the same actions and effects as those of claims 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, and 11 can be obtained.

[ solution 18]

Another aspect of the present invention for achieving the above object is to provide: a steering shaft disposed with a lower end side thereof inserted into the transmission case; a link lever arm provided at a lower side of the transmission case; and an arm support shaft disposed at a bottom of the transmission case and configured to swing the link arm, wherein the steering shaft and the arm support shaft are configured to be interlocked with each other by a pinion gear provided in the steering shaft and a steering gear provided in the arm support shaft and engaged with the pinion gear, on a bottom side in the transmission case, and the arm support shaft is pivotally supported by an upper 2 nd bearing portion provided on an upper side of the steering gear, the upper 2 nd bearing portion being supported by an arm side mounting portion extending from a case wall of the transmission case, and a vertical rib for reinforcing a load in a vertical direction is formed on the arm side mounting portion.

[ action and Effect of claim 18]

According to the structure of claim 18, since the upper 2 nd bearing portion that supports the upper side of the arm support shaft is supported by the arm side mounting portion that protrudes from the wall of the transmission case and has the vertical rib for reinforcing the load in the vertical direction, the strength of the arm side mounting portion against the load in the vertical direction can be increased with a relatively lightweight structure.

Therefore, there are advantages in that: when the arm support shaft of the connecting lever arm is provided on the bottom side of the transmission case, damage to the arm-side mounting portion and the like can be easily suppressed even when the arm support shaft is knocked in from below and a large load acts on the arm-side mounting portion from below.

[ solution 19]

In another aspect of the present invention to achieve the above object, the longitudinal rib is formed to extend across an upper surface of the arm-side mounting portion and a lateral wall of the transmission case.

[ action and Effect of claim 19]

According to the structure of claim 19, since the vertical rib for reinforcing the vertical load acting on the arm-side mounting portion is formed so as to straddle the upper surface of the arm-side mounting portion and the lateral wall of the transmission case, the reinforcing structure of the arm-side mounting portion can be simply configured by the lateral wall and the vertical rib of the transmission case.

[ solution 20]

In another aspect of the present invention to achieve the above object, the upper 1 st bearing portion located on the upper side of the pinion is supported by an axle-side mounting portion formed across the front wall and the lateral wall of the transmission case, the axle-side mounting portion and the arm-side mounting portion are integrally connected to each other by an intermediate connecting portion located between the axle-side mounting portion and the arm-side mounting portion.

[ action and Effect of claim 20]

According to the structure of claim 20, since the shaft-side mounting portion and the arm-side mounting portion are integrally connected by the intermediate connecting portion, there is an advantage in that: the support strength of a steering shaft supported by an axle-side mounting portion and an arm support shaft supported by the arm-side mounting portion can be improved with a simple configuration.

[ solution 21]

In another aspect of the present invention to achieve the above object, the longitudinal ribs are formed at both front and rear sides of the upper 2 nd bearing portion.

[ action and Effect of claim 21]

The structure according to claim 21 has the following advantages: the strength of the front and rear side positions of the 2 nd bearing part can be improved.

[ solution 22]

In another aspect of the present invention to achieve the above object, among the longitudinal ribs, a longitudinal rib on a side away from the steering shaft is formed larger than a longitudinal rib on a side close to the steering shaft.

[ action and Effect of claim 22]

According to the structure of claim 22, the longitudinal rib on the side away from the steering shaft is formed larger than the longitudinal rib on the side close to the steering shaft, and therefore, there is an advantage in that: further, in the case where the shaft-side mounting portion and the arm-side mounting portion are coupled by the intermediate coupling portion, the side away from the steering shaft, which is not coupled to the intermediate coupling portion, can be reinforced firmly, and durability can be further improved.

[ solution 23]

In another aspect of the present invention for achieving the above object, the longitudinal ribs are connected to each other by a transverse rib extending in a horizontal direction.

[ action and Effect of claim 23]

The structure according to claim 23 has the following advantages: by connecting the longitudinal ribs, the strength can be further improved.

[ solution 24]

Another aspect of the present invention for achieving the above object is to provide: a steering shaft disposed with a lower end side thereof inserted into the transmission case; a link lever arm provided at a lower side of the transmission case; and an arm support shaft disposed at a bottom of the transmission case and configured to swing the link arm, wherein the steering shaft and the arm support shaft are linked by a pinion gear provided in the steering shaft and a steering gear provided in the arm support shaft and meshing with the pinion gear, the arm support shaft is pivotally supported by an upper 2 nd bearing portion provided on an upper side of the steering gear, the upper 2 nd bearing portion is supported by an arm side mounting portion provided on a lateral wall of the transmission case, vertical ribs for reinforcing a vertical load are formed on the arm side mounting portion, the vertical ribs are formed on front and rear sides of the upper 2 nd bearing portion across an upper surface of the arm side mounting portion and the lateral wall of the transmission case, and an upper 1 st bearing portion located near an upper side of the pinion gear is supported by an axle side mounting portion, the shaft-side mounting portion is formed to extend 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, the intermediate connecting portion is located between the shaft-side mounting portion and the arm-side mounting portion, a longitudinal rib on a side remote from the steering shaft is formed larger than a longitudinal rib on a side close to the steering shaft, and the longitudinal ribs are connected to each other by a lateral rib along a horizontal direction.

[ action and Effect of claim 24]

With the configuration of claim 24, the same actions and effects as those of claims 18, 19, 20, 21, 22, and 23 can be obtained.

Drawings

Fig. 1 is a right side view of the riding rice transplanter.

Fig. 2 is a right side view showing the transmission and the vehicle body frame.

Fig. 3 is a plan view showing the transmission case.

Fig. 4 is a longitudinal sectional view of the transmission.

Fig. 5 is a sectional view showing a lower bearing portion of the steering shaft.

Fig. 6 is a perspective view of the main body portion of the transmission.

Fig. 7 is a circuit diagram showing a power transmission system to a running device.

Fig. 8 is a circuit diagram showing a power transmission system to the seedling planting device.

Description of the symbols

3 speed changing box

4-power steering device

4a output shaft

30 case main body part

31 cover-shaped box part

30b bottom wall

30f front wall

30s transverse wall

32 bottom opening

34 axle side mounting part

35 intermediate connection part

36 arm side mounting part

37 longitudinal rib

37a proximal longitudinal rib

37b distal longitudinal rib

38 transverse rib

41 steering shaft

42 pinion

43d lower 1 st bearing part

43u Upper 1 st bearing section

44 connecting rod arm

45-arm fulcrum shaft

46 steering gear

48u Upper 2 nd bearing part

D2 outer diameter

D3 inner diameter

Detailed Description

An example of an embodiment of the present invention will be described below with reference to the drawings.

[ integral Structure ]

Fig. 1 shows a right side surface of a riding type rice transplanter as an example of a working vehicle.

The riding rice transplanter has a self-propelled traveling vehicle body 1, and the traveling vehicle body 1 has a pair of left and right steerable and drivable front wheels 11F and a pair of left and right drivable rear wheels 11R below a vehicle body frame 10, and drives the front wheels 11F and the rear wheels 11R by receiving power from an engine E mounted on the vehicle body frame 10.

The traveling vehicle body 1 has a power unit 13 with an engine E incorporated therein at a front portion thereof, and preliminary seedling stages 14 on both left and right sides thereof. A riding section having a steering handle 15 and a driver seat 12 for steering the front wheels 11F is provided at the central portion in the front-rear direction of the running vehicle body 1 on the rear side of the power section 13. The seedling planting device 2 is supported by a link mechanism 17 provided with a lift cylinder 18 at the rear of the traveling vehicle body 1 so as to be able to be lifted and lowered.

The riding rice transplanter having the above-described structure is a machine for performing a planting operation of planting rice or other seedlings on the ground by the seedling planting device 2 as a "work on the ground".

The seedling planting device 2 is configured as an eight-row planting type, and comprises: four gear boxes 21; a seed planting box 22 rotatably supported on the right and left lateral sides of the rear part of the transmission box 21; a pair of planting arms 23 provided at both ends of the planting box 22; a grounded float 24; and a seedling stage 20 for carrying seedlings. Thus, the seedling stage 20 is driven to be fed horizontally in a reciprocating manner, the planting box 22 is driven to rotate, and the planting arms 23 alternately take out the seedlings from the lower portion of the seedling stage 20 and plant the seedlings on the field surface.

A transmission case 3 that pivotally supports front wheels 11F is fixedly coupled to a front portion of a vehicle body frame 10 of the traveling vehicle body 1, and a rear transmission case 19 equipped with rear wheels 11F on the right and left sides and capable of rolling is supported on a rear portion of the vehicle body frame 10. The front frame 10F extends forward from the transmission case 3, and the engine E is transversely mounted on the front frame 10F.

As shown in fig. 2 to 4, the front axle boxes 3A extend to the left and right outside on both left and right sides of the transmission 3, and left and right front wheels 11F, 11F are provided. A torque generator 4 (corresponding to a power steering device) is provided above the transmission 3, and a steering handle 15 is provided at an upper end of a steering shaft 15a that is provided so as to stand upward from the torque generator 4. A main shift lever 16 that changes the vehicle speed by operating a hydrostatic continuously variable transmission 61, which will be described later, is disposed on a lateral side portion of the steering handle 15.

[ Power Transmission System ]

A power transmission system for transmitting the power of the engine E to the front wheels 11 and the rear wheels 11R of the travel drive system and a power transmission system for transmitting the power to the seedling planting device 2 as a working device will now be described.

[ about a travel drive System ]

As shown in fig. 3, a pair of left and right front axle boxes 3A are provided on both left and right lateral sides of the transmission 3. The front wheel 11F is supported on the front axle box 3A to be rotatable about an axis in the vertical direction.

As shown in fig. 3 and 7, a hydrostatic continuously variable transmission 61 is connected to the transmission 3 in a state of being positioned at a left lateral side portion on an upper side of the transmission 3. The hydrostatic continuously variable transmission 61 has an intermediate stop position, and continuously variable transmission is performed from the intermediate stop position to the forward side and the reverse side. The hydrostatic continuously variable transmission 61 includes a shift input shaft 61a and a shift output shaft 61b extending outward. The power of the engine E is transmitted to the shift input shaft 61a of the hydrostatic continuously variable transmission 61 through the belt transmission 61 c. The portion of the shift input shaft 61a on the opposite side of the belt transmission mechanism 61c and the shift output shaft 61b are arranged in a state of entering the inside of the transmission case 3.

A hydraulic pump 62 is connected to a right lateral side portion of the transmission 3. The pump input shaft 62a of the hydraulic pump 62 is configured to enter a state inside the transmission case 3. The pump input shaft 62a is disposed concentrically with the shift input shaft 61a, and is spline-connected by the extension input shaft 61d so as to rotate integrally with the shift input shaft 61 a. Thus, 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 rotatably supported inside the transmission case 3 is spline-coupled to the transmission output shaft 61 b. A first shift gear 64 that is slidable with respect to the first transmission shaft 63 is externally fitted to the first transmission shaft 63 by a spline structure. The first shift gear 64 integrally includes a first high-speed gear 64a and a first low-speed gear 64b having a larger diameter than the first high-speed gear 64 a.

A second propeller shaft 65 parallel to the first propeller shaft 63 is supported in the transmission case 3 on the downstream side of the transmission of the first propeller shaft 63. A large-diameter gear 65a and an intermediate-diameter gear 65b smaller in diameter than the large-diameter gear 65a are fixed to the second transmission shaft 65. By performing a shift operation on the first shift gear 64, any one of the engagement of the first high-speed gear 64a with the large diameter gear 65a and the engagement of the first low-speed gear 64b with the medium diameter gear 65b is selected, and power can be transmitted from the first 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 transmission downstream side of the second transmission shaft 65, a third transmission shaft 67 parallel to the second transmission shaft 65 is supported in the transmission case 3. A second shift gear 68 that rotates integrally with the third transmission shaft 67 and is slidable relative to the third transmission shaft 67 is externally fitted 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 larger diameter than the second high-speed gear 68 a. By performing a shift operation on the second shift gear 68, any one of the engagement of the intermediate diameter gear 65b with the second high speed gear 68a and the engagement of the small diameter gear 65c with the second low speed gear 68b is selected, and power can be transmitted from the second transmission 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.

A pair of front side propeller shafts 71 are disposed in parallel to the third propeller shaft 67 in a butt joint manner on the downstream side of the third propeller shaft 67. A differential mechanism 72 is provided between the pair of front side transmission shafts 71. The differential case 72a of the differential mechanism 72 is rotatably supported inside the transmission case 3. The transmission gear 69 fixed to the third transmission shaft 67 meshes with the driven gear 72b fixed to the differential case 72 a.

A differential lock body 72c that is rotatable and slidable integrally is fitted to one of the pair of front propeller shafts 71 by a key structure. The differential lock 72c can be switched to these two states: a differential enabled state (differential lock released state) in which engagement with the differential case 72a is released; and a non-differential state (differential lock state) in which the differential case 72a is engaged.

As shown in fig. 2 and 7, a travel output shaft 74 projecting rearward from a rear end portion of the transmission case 3 is provided at a rear portion of the transmission case 3. The traveling output shaft 74 has a second bevel gear 75 at its front end portion. The second bevel gear 75 meshes 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 is provided for supporting the pair of left and right rear wheels 11R, and a rear transmission shaft 77 is coupled in an interlocking manner between the travel output shaft 74 and a 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.

Thus, the power of the engine E is transmitted to the pair of left and right front wheels 11F through 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 side transmission shaft 71 of the hydrostatic continuously variable transmission 61, and is transmitted to the pair of left and right rear wheels 11R through the differential case 72a, the travel output shaft 74, and the rear side transmission shaft 76 of the differential mechanism 72.

[ working device drive System ]

Next, a transmission structure of the working device, i.e., the seedling planting device 2 will be described.

As shown in fig. 8, a fourth propeller shaft 80 parallel to the second propeller shaft 65 is supported in the transmission case 3 on the transmission downstream side of the second propeller shaft 65. An output gear 81 for work is fixed to the second power transmission shaft 65. The power of the second transmission shaft 65 is transmitted from the output gear 81 for work to the fourth transmission shaft 80 through the torque limiter T.

A planting shift gear 84 that rotates integrally with the fourth transmission shaft 80 and is slidable relative to the fourth transmission shaft 80 is externally fitted to the fourth transmission shaft 80 by a spline structure. The planting shift gear 84 integrally includes a first planting low-speed gear 84a and a first planting high-speed gear 84b that is smaller in diameter than the first planting low-speed gear 84 a.

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 that are supported rotatably relative to the first transmission shaft 63. 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 to rotate integrally. The diameters of the gears are increased in the order of 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 85 e.

The planting shift gear 84 is configured to be able to select one of the engagement between the first planting low-speed gear 84a and the first loose fitting gear 85a and the engagement between the first planting high-speed gear 84b and the fifth loose fitting gear 85e by sliding the second shift operating lever 27. This makes it possible to perform a two-stage speed change of the power transmitted from the planting shift gear 84 to the downstream side of the transmission. In this way, the planting shift gear 84, the second shift operating lever 27, the first loose fitting gear 85a, the fifth loose fitting gear 85e, and the like constitute the second transmission mechanism S2 disposed in the transmission case 3. That is, the second speed change mechanism S2 changes the interval (inter-plant) of the seedling planting work as the "ground work" by the seedling planting device 2 as the "work device" in two stages by changing the speed of the power from the engine E in two stages (an example of "multi-stage").

A fifth propeller shaft 86 parallel to the first propeller shaft 63 is supported in the transmission case 3 on the downstream side of the transmission of the fourth propeller shaft 80 and the first propeller shaft 63. A first transmission gear 87a, a second transmission gear 87b, a third transmission gear 87c, and a fourth transmission gear 87d are rotatably supported on the fifth transmission shaft 86. The diameters of the gears are reduced in the order of the first transmission gear 87a, the second transmission gear 87b, the third transmission gear 87c, and the fourth transmission gear 87 d. The first loose fitting gear 85a is always engaged with the first transmission gear 87a, the second loose fitting gear 85b is always engaged with the second transmission gear 87b, the third loose fitting gear 85c is always engaged with the third transmission gear 87c, and the fourth loose fitting gear 85d is always engaged with the fourth transmission gear 87 d. A third bevel gear 88 is fixed to the fifth transmission shaft 86.

The first shift operating lever 26 inserted into the center of the fifth transmission shaft 86 is slidably moved in the axial direction, and a transmission ball (not shown) engaged and supported by the fifth transmission shaft 86 is pushed out and displaced radially outward by a large-diameter cam portion 26b provided on one end side of the first shift operating lever 26. By engaging the transmission balls with the center 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 of the four pairs of gears that are always in mesh is selected and mesh transmission is performed, and four-stage speed change of the power transmitted to the driven fifth transmission shaft 86 is possible. In this way, the first transmission gear 87a, the second transmission gear 87b, the third transmission gear 87c, the fourth transmission gear 87d, the first shift operating lever 26, the transmission balls, and the like constitute a first shift mechanism S1 disposed in the transmission case 3. That is, the first speed change mechanism S1 changes the speed of the power from the engine E in four stages (an example of "multi-stage") to change the interval (inter-plant) of the seedling planting work as the "ground work" by the seedling planting device 2 as the "work device" in four stages.

In this way, the power of the planting system can be shifted by a combination of the four-stage shift by operating the first shift operating lever 26 and the two-stage shift by operating the second shift operating lever 27, thereby making it possible to perform a total of eight-stage shift.

A cylindrical body 90 is provided on the rear side of the transmission case 3, and the cylindrical body 90 is supported to be rotatable relative to the transmission case 3. The cylinder 90 has a fourth bevel gear 91. A fourth bevel gear 91 meshes with a third bevel gear 88 fixed to the fifth transmission shaft 86.

A planting output shaft 92 is provided at the rear of the transmission case 3, and the planting output shaft 92 projects rearward from the rear end of the transmission case 3 and is positioned inside the cylindrical body 90 concentrically with the cylindrical body 90. A planting clutch 93 that rotates integrally with the planting output shaft 92 and slides freely relative 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 to these two states: a locked state in which the cylinder 90 is locked; and an engagement released state in which the cylinder 90 is not engaged. When the planting clutch 93 is engaged, the power of the fifth transmission shaft 86 is transmitted to the planting output shaft 92 through the third bevel gear 88, the fourth bevel gear 91, the cylinder 90 and the planting clutch 93. On the other hand, when the planting clutch 93 is in the engagement-released state, the power transmission from the fifth transmission shaft 86 to the planting output shaft 92 can be cut off. The planting clutch 93 is biased to the side that is in the engaged state, and is configured to switch between the engaged state and the disengaged state by moving the operating shaft 94 supported by the bushing 95 forward and backward.

As shown in fig. 8, the power of the planting output shaft 92 is transmitted to the input shaft 98 of the feeding box 97 by rotating the transmission shaft 96. The driving of the planting arms 23 and the reciprocating movement of the seedling placing table 20 in conjunction with the seedling planting operation of the planting arms 23 are performed by the power input to the input shaft 98. Thus, the seedlings are planted on the ground at the planting speed changed by the first speed changing mechanism S1 and the second speed changing mechanism S2 according to the traveling speed of the machine body. Thus, the first speed change mechanism S1 and the second speed change mechanism S2 can be operated to perform rice transplanting at a desired planting interval (inter-plant).

[ Structure of Transmission case ]

Fig. 3 to 6 show an internal structure of the transmission case 3.

The transmission case 3 is formed by combining split cases: a box-shaped box main body 30 having an opening 30a formed at one end side in the left-right direction, and a lid-shaped box 31 for closing the opening 30. The box main body 30 and the lid-like box 31 are aluminum die-cast parts, and are integrated by bolting the lid-like box 31 to face the opening 30a of the box main body 30.

As shown in fig. 4 and 6, the box main body 30 includes: a front wall 30f constituting a front surface in a traveling direction of the body of the box-shaped transmission case 3; a rear wall 30r constituting a rear surface of the transmission case 3; an upper wall 30t constituting an upper surface of the transmission case 3; a bottom wall 30b constituting a bottom surface of the transmission case 3; and a lateral wall 30s constituting a left side surface of the transmission case 3. The lid-like case portion 31 constitutes the right side surface of the transmission case 3, and the entire transmission case 3 is formed in a substantially rectangular case shape.

As shown in fig. 2 to 4, a hydraulic torque generator 4 as a power steering device in a slightly backward posture is mounted on the upper surface of the transmission case 3 at a front position of the upper wall 30t of the case main body 30. The steering shaft 15a extends obliquely rearward and upward from the torque generator 4. A downward output shaft 4a is provided from the lower side of the torque generator 4 so as to concentrically protrude into the transmission case 3 coaxially with the steering shaft 15 a.

A steering shaft 41 having a coaxial shape with the output shaft 4a and the steering shaft 15a is coupled to a lower end side of the output shaft 4a via a coupling 40 having a spline portion on an inner peripheral side. That is, splines are formed on the outer periphery of the upper end portion 41a of the steering shaft 41, and the splines engage with the splines on the inner periphery of the coupling 40.

As shown in fig. 4 to 6, a bottom opening 32 for inserting and removing the steering shaft 41 is formed at a front position of the transmission case 3 on the bottom wall 30b side of the case main body 30.

The bottom opening 32 is formed so as to be able to insert and remove the steering shaft 41 from the lower side of the transmission case 3, and also serves as a mounting portion for a lower bearing 43d (corresponding to the lower 1 st bearing portion) that pivotally supports the lower end side of the steering shaft 41.

A pinion gear 42 is integrally formed in the vicinity of the lower end of the steering shaft 41 opposite to the upper end 41a, and a lower bearing 43d is fitted around a shaft portion of the steering shaft 41 extending downward from a portion where the pinion gear 42 is present, and fitted into the bottom opening 32.

A separate bottom opening 33 is formed in the bottom wall 30b of the case main body 30 of the transmission case 3 at a position separated to the rear side from the position where the bottom opening 32 for inserting and removing the steering shaft 41 is formed, and an arm support shaft 45 provided to rotate integrally with the link arm 44 is attached to the opening 33. The other bottom opening 33 also serves as an attachment portion for a lower bearing 48d (corresponding to the lower 2 nd bearing portion), and the lower bearing 48d pivotally supports the arm support shaft 45.

The arm support shaft 45 is pivotally supported on the lower bearing 48d, and has an upper outer peripheral surface formed with splines that engage with splines formed on the inner peripheral side of a sector gear 46 (corresponding to a steering gear), and the sector gear 46 is attached to be detachable from and integrally rotatable with the arm support shaft 45.

The sector gear 46 meshes with the pinion gear 42 of the steering shaft 41, and the sector gear 46 is rotationally operated in accordance with the rotation of the steering shaft 41. The link lever arm 44 is swung within a predetermined angular range by an arm pivot shaft 45 that pivots with the sector gear 46.

A tie rod 47 connected to a free end portion of the link arm 44 is linked to an unillustrated articulated arm, and the left and right front wheels 11F, 11F are steered in accordance with the amount of swing motion of the link arm 44.

As shown in fig. 4 and 5, the steering shaft 41 is pivotally supported by an upper bearing 43u (corresponding to the upper 1 st bearing portion) not only on a shaft portion extending downward from a portion where the pinion gear 42 is present, but also on an upper side of the pinion gear 42.

As shown in fig. 4 to 6, the upper bearing 43u is mounted on the shaft-side mounting portion 34, and the shaft-side mounting portion 34 projects horizontally from the front wall 30f and the lateral wall 30s of the transmission case 3 inside the transmission case 3.

As shown in fig. 5, a recess 34a into which the upper bearing 43u can be fitted from below is formed on the lower surface side of the shaft-side mounting portion 34, and the upper bearing 43u is fitted from below to pivotally support the steering shaft 41.

The upper bearing 43u and the lower bearing 43D have outer diameters slightly smaller than the inner diameter D3 of the bottom opening 32, are fitted with appropriate fitting tolerances, and are configured to be insertable into and removable from the bottom opening 32 of the transmission case 3. 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 an appropriate fitting tolerance, and are set smaller than the outer diameter D2 of the pinion gear 42.

The upper bearing 43u and the lower bearing 43d are fitted into the recess 34a in a state where the upper bearing 43u and the lower bearing 43d are in contact with the upper end edge and the lower end edge of the pinion gear 42 and hold the pinion gear 42 therebetween in the vertical direction, and the lower bearing 43d is held in the bottom opening 32 in a slip-off prevention state by the retainer ring 32 a.

As shown in fig. 4 and 5, the arm support shaft 45 is pivotally supported by an upper bearing 48u (corresponding to the upper 2 nd bearing section) not only on a shaft portion located on the lower side of the portion where the sector gear 46 is located, but also on the upper side of the sector gear 46.

As shown in fig. 4 to 6, the upper bearing 48u is attached to the arm-side mounting portion 36, and the arm-side mounting portion 36 horizontally protrudes from the lateral wall 30s of the transmission case 3 inside the transmission case 3.

As shown in fig. 5, a recess 36a into which the upper bearing 48u can be fitted from below is formed on the lower surface side of the arm-side mounting portion 36, and the upper bearing 48u is fitted from below to pivotally support the arm support shaft 45.

The upper bearing 48u and the lower bearing 48D have outer diameters slightly smaller than the inner diameter D6 of the bottom opening 33, are fitted with appropriate fitting tolerances, and are configured to be insertable into and removable from the bottom opening 32 of the transmission case 3.

The lower bearing 48D is fitted with an inner diameter slightly larger than the outer diameter D5 of the spline portion of the arm support shaft 45 with an appropriate fitting tolerance, and the upper bearing 48u is fitted with an inner diameter slightly larger than the outer diameter D4 of the shaft portion above the spline portion of the arm support shaft 45 with an appropriate fitting tolerance.

The upper bearing 48u and the lower bearing 48d are fitted into the recess 36a in a state where the upper bearing 48u and the lower bearing 48d are in contact with the upper end edge and the lower end edge of the sector gear 46 and vertically sandwich the sector gear 46, and the lower bearing 48d is held in a slip-off state by the retainer ring 33a in the bottom opening 33.

As shown in fig. 4 to 6, the shaft-side mounting portion 34 and the arm-side mounting portion 36 are integrally connected to each other by an intermediate connecting portion 35, and the intermediate connecting portion 35 is located between the shaft-side mounting portion 34 and the arm-side mounting portion 36. The intermediate connecting portion 35 is formed to protrude from the inner surface of the left lateral wall 30s of the box main body portion 30 in a rib shape, and is not formed with a recess for mounting a bearing, and therefore, as shown in the drawing, the thickness in the vertical direction is formed to be thinner than the shaft-side mounting portion 34 and the arm-side mounting portion 36, and the amount of protrusion from the left lateral wall 30s is also smaller than the shaft-side mounting portion 34 and the arm-side mounting portion 36 in a 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 formed to have a greater vertical thickness than the intermediate connection portion 35 and to be wider in the horizontal direction than the intermediate connection portion 35.

The intermediate connecting portion 35 has a smaller thickness and a smaller area than the shaft-side mounting portion 34 and the arm-side mounting portion 36, but since the shaft-side mounting portion 34 and the arm-side mounting portion 36 are connected, the weight of the transmission case 3 can be prevented from being increased as much as possible, and 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 across the upper surface of the arm-side mounting portion 36 and the left lateral wall 30s of the case main body portion 30 of the transmission case 3. The vertical rib 37 has a plate surface in the vertical direction parallel to the axial center of the arm support shaft 45 supported by the arm-side mounting portion 36, and is provided to be able to effectively reinforce the vertical load acting on the arm-side mounting portion 36.

The vertical ribs 37 are positioned on both front and rear sides of an upper bearing 48u that pivotally supports the arm support shaft 45. Further, of the longitudinal ribs 37 in the front and rear, the longitudinal rib 37b on the side far from the steering shaft 41 is formed larger than the longitudinal rib 37a on the side near the steering shaft 41.

Further, the vertical ribs 37a and 37b are connected to each other by the horizontal transverse rib 38, thereby further increasing the rigidity.

[ Another embodiment ]

In the above embodiment, the configuration is exemplified: the operation of the steering handle 15 is transmitted to the torque generator 4 through the steering operation shaft 15a, and the output of the torque generator 4 is transmitted to the connection lever arm 44 through the steering shaft 41, but is not limited to this configuration.

For example, the torque generator 4 may be omitted, and the operation of the steering handle 15 may be directly transmitted to the steering shaft 41, and the link lever arm 44 may be operated in accordance with the operation of the steering shaft 41.

The other structures may be the same as those of the foregoing embodiments.

[ second embodiment ]

In the above-described embodiment, the transmission case 3 is exemplified by a structure including a split case body including the case main body portion 30 and the lid case portion 31 which are split into the upper and lower portions and the left and right portions in the front-rear direction by the split surface, but the structure is not limited to this structure. For example, the partition surface may be divided into a structure in which the partition surface is vertically divided in the left-right direction and the front-rear direction, or a structure in which the partition surface is vertically divided in the horizontal direction.

The other structures may be the same as those of the foregoing embodiments.

[ third embodiment ]

In the above-described embodiment, the structure in which the shaft-side mounting portion 34 is integrally formed on both the front wall 30f and the lateral wall 30s of the box main body portion 30 has been illustrated, but the present invention is not limited thereto. For example, the shaft-side mounting portion 34 may be formed to protrude from the lateral wall 30s away from the front wall 30f of the box main body 30, or the shaft-side mounting portion 34 may be formed to protrude from the front wall 30f away from the lateral wall 30s of the box main body 30.

The shaft-side mounting portion 34 may be provided so as to stand from the bottom wall 30b while being separated from the front wall 30f and the lateral wall 30s of the box body 30.

The other structures may be the same as those of the foregoing embodiments.

[ fourth embodiment ]

In the above-described embodiment, the arm-side mounting portion 36 is integrally formed with the lateral wall 30s of the box main body portion 30, but the present invention is not limited thereto. For example, the arm-side mounting portion 36 may be provided to stand from the bottom wall 30b apart from the lateral wall 30s of the box main body portion 30.

The other structures may be the same as those of the foregoing embodiments.

[ fifth embodiment ]

In the above-described embodiment, the structure in which the shaft-side mounting portion 34 and the arm-side mounting portion 36 are formed integrally with the intermediate connecting portion 35 has been exemplified, but the shaft-side mounting portion 34 and the arm-side mounting portion 36 may be formed to protrude independently from one inner wall of the box main body portion 30 without using the intermediate connecting portion 35.

The other structures may be the same as those of the foregoing embodiments.

Industrial applicability of the invention

The working vehicle to which the present invention is applied is not limited to a riding type rice transplanter, and may be other paddy field working machines such as a walking type rice transplanter, a riding type direct seeder, and a walking type direct seeder, and may be various agricultural working machines such as a tractor, a mower, a carrier, and the like.

Claims (14)

1. A riding rice transplanter or a riding direct seeder, comprising:

a steering shaft disposed with a lower end side thereof inserted into the transmission case;

a link lever arm provided at a lower side of the transmission case; and

an arm support shaft disposed at a bottom of the transmission case and configured to swing the link arm,

the steering shaft and the arm support shaft are interlocked by engaging a pinion gear provided in a lower portion of the steering shaft in the transmission case with a steering gear provided in the arm support shaft in the transmission case,

the steering shaft is supported at two positions, i.e., an upper position and a lower position, which sandwich the pinion gear, by a lower 1 st bearing portion and an upper 1 st bearing portion, the lower 1 st bearing portion being provided below the pinion gear, the upper 1 st bearing portion being provided above the pinion gear at a lower portion of the transmission case space,

the upper 1 st bearing portion is supported on an axle-side mounting portion that projects from a wall of the transmission case,

the axle-side mounting portion is formed across the front wall and the lateral wall of the transmission case,

the arm support shaft is pivotally supported by an upper 2 nd bearing part provided on an upper side of the steering gear, the upper 2 nd bearing part being supported by an arm side mounting part provided on a lateral wall of the transmission case,

an axle-side mounting portion extending from a wall of the transmission case and the arm-side mounting portion are integrally connected to each other via an intermediate connecting portion between the axle-side mounting portion and the arm-side mounting portion,

the intermediate connecting portion is formed to protrude from an inner surface of a lateral wall of the transmission case in a rib shape.

2. The rice transplanter or direct seeder according to claim 1, wherein the transmission is configured to be openable and closable, and has a box-shaped box body portion having an opening formed at one end side in the left-right direction, and a lid-shaped box portion closing the opening, and the shaft-side mounting portion is provided in the box body portion.

3. The rice transplanter or direct seeder 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 1 st bearing portion is provided in the bottom opening.

4. The rice transplanter or direct seeder according to claim 3, wherein the lower 1 st bearing portion is configured to be attachable to and detachable from the bottom opening from a lower side, an inner diameter of the lower 1 st bearing portion is formed smaller than an outer diameter of the pinion, and an outer diameter of the lower 1 st bearing portion is formed larger than the outer diameter of the pinion.

5. The rice transplanter or direct seeder according to claim 4, wherein the upper 1 st bearing portion is formed such that an outer diameter of the upper 1 st bearing portion is smaller than an inner diameter of the bottom opening.

6. The rice transplanter or direct seeder according to claim 1, wherein the shaft-side mounting portion, the arm-side mounting portion, and the intermediate connecting portion constitute a bearing mounting portion, and 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 of the bearing mounting portion are formed to be wider in the left-right direction than the intermediate connecting portion in a plan view.

7. The rice transplanter or direct seeder according to any one of claims 1, 2, and 6, wherein an upper end side of the steering shaft is coupled to an output shaft of a power steering device provided above the transmission case.

8. The riding rice transplanter or riding direct seeder of claim 1,

the steering shaft and the arm support shaft are configured to be interlocked with each other at a bottom side in the transmission case,

the arm support shaft is pivotally supported by an upper 2 nd bearing portion provided above the steering gear, the upper 2 nd bearing portion being supported by an arm side mounting portion extending from a wall of the transmission case, and a vertical rib for reinforcing a vertical load being formed on the arm side mounting portion.

9. The riding rice transplanter or riding direct seeder of claim 8, wherein the longitudinal rib is formed across an upper surface of the arm-side mounting portion and a lateral wall of the transmission case.

10. The rice transplanter or direct seeder according to claim 8 or 9, wherein the upper 1 st bearing portion located close to the upper side of the pinion is supported by an axle-side mounting portion formed across the front wall and the lateral wall of the transmission case,

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.

11. The rice transplanter or direct seeder according to claim 8 or 9, wherein the longitudinal ribs are formed at positions on both front and rear sides of the upper 2 nd bearing portion.

12. The riding rice transplanter or riding direct seeder according to claim 11, wherein a side of the longitudinal ribs remote from the steering shaft is formed larger than a side of the longitudinal ribs near the steering shaft.

13. The riding rice transplanter or riding direct seeder of claim 11, wherein the longitudinal ribs are connected to each other by transverse ribs in the horizontal direction.

14. The riding rice transplanter or riding direct seeder of claim 8,

the steering shaft and the arm support shaft are configured to be interlocked with each other at a bottom side in the transmission case,

the arm support shaft is pivotally supported by an upper 2 nd bearing part provided on an upper side of the steering gear, the upper 2 nd bearing part is supported by an arm side mounting part provided on a lateral wall of the transmission case, a vertical rib for reinforcing a load in a vertical direction is formed on the arm side mounting part,

longitudinal ribs formed on both front and rear sides of the upper 2 nd bearing portion across an upper surface of the arm-side mounting portion and a lateral wall of the transmission case,

an upper 1 st bearing portion located near an upper side of the pinion is supported by an axle-side mounting portion formed across a front wall and a lateral wall of the transmission case and integrally connected to the arm-side mounting portion by an intermediate connecting portion located between the axle-side mounting portion and the arm-side mounting portion,

the longitudinal rib on the side far from the steering shaft is formed larger than the longitudinal rib on the side near the steering shaft,

the longitudinal ribs are connected to each other by transverse ribs extending in the horizontal direction.

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