JP7801993B2 - Paddy field farming machine - Google Patents

Description

The present invention relates to a paddy field working machine in which working devices such as seedling planting devices and sowing devices are supported at the rear of a body supported by running wheels so that they can be raised and lowered.

In a riding rice transplanter, which is an example of a paddy field working machine, as disclosed in Patent Documents 1 and 2, a float is supported at the bottom of the seedling planting device (equivalent to the working device) so that it can swing up and down, and the float follows the ground surface of the rice field.
In Patent Documents 1 and 2, a height detection unit that detects the height of the seedling planting device from the float is provided on the float, and the height of the seedling planting device from the float is detected by the height detection unit as the height of the seedling planting device from the rice field surface.

Based on the detection by the height detection unit, the seedling planting device is automatically raised and lowered relative to the machine body so that the seedling planting device is maintained at a preset height above the rice field surface, and the planting depth of the seedlings in the seedling planting device is maintained at a preset depth.

Japanese Patent Application Laid-Open No. 2013-59267 (see 54, 55, and 68 in FIG. 6) Japanese Patent Application Laid-Open No. 2016-49067 (see 41 in FIG. 3)

When a paddy field working machine is equipped with a float and a height detection unit, a regulating mechanism may be provided for the float, and the regulating mechanism restricts the float to an upper or lower limit position relative to the working device when it swings up and down relative to the seedling planting device.

The present invention aims to simplify the structure of a paddy field working machine when the height detection unit and regulating mechanism are mounted on a float.

The paddy field working machine of the present invention comprises a body supported by wheels for running, a working device supported at the rear of the body so that it can be raised and lowered, a float supported at the bottom of the working device so that it can swing up and down and follows the surface of the rice field, a height detection unit that detects the height of the working device from the float, a lifting control unit that raises and lowers the working device relative to the body based on the detection by the height detection unit so that the working device is maintained at a predetermined height above the surface of the rice field, and a regulating mechanism that is provided separately from the height detection unit and regulates at least one of the upper and lower limit positions of the float 's up and down swing relative to the working device, the height detection unit being provided on one of the right and left sides of the part of the float that is supported on the working device so that it can swing up and down, and the regulating mechanism being provided on the other of the right and left sides of the part of the float that is supported on the working device so that it can swing up and down .

According to the present invention, a height detection unit that detects the height of the work device from the float is provided on the float, and based on the detection by the height detection unit, the work device is raised and lowered relative to the machine body by the lifting control unit so that the work device is maintained at a predetermined set height from the rice field surface.
According to the present invention, the float is provided with a restriction mechanism, and when the float swings up and down relative to the working device, the restriction mechanism restricts the float to at least one of the upper limit position and the lower limit position of the up and down swing relative to the working device.
Furthermore, since the height detection unit and the regulating mechanism are provided at different positions on the left and right sides of the float, interference between the height detection unit and the regulating mechanism is further reduced, and the configuration to avoid interference between the height detection unit and the regulating mechanism is unnecessary or small-scale, which is advantageous in terms of simplifying the structure when providing the height detection unit and the regulating mechanism.

In the present invention,
a body supported by wheels for running;
a working device supported at the rear of the machine body so as to be able to rise and fall;
a float supported on the lower part of the working device so as to be able to swing up and down and follow the ground contact with the rice field surface;
a height detection unit that detects the height of the working device from the float;
an elevation control unit that raises and lowers the working device relative to the machine body based on detection by the height detection unit so that the working device is maintained at a preset height from the rice field surface;
a restriction mechanism provided separately from the height detection unit and configured to restrict the float to at least one of an upper limit position and a lower limit position of up-and-down swing relative to the working device,
the height detection unit has a restriction unit that restricts the float to one or both of an upper limit position and a lower limit position relative to the working device,
the regulating mechanism regulates the float to both an upper limit position and a lower limit position of up-and-down swing relative to the working device,
It is preferable that the upper limit position of the restriction mechanism is set above the upper limit position of the restriction portion, and the lower limit position of the restriction mechanism is set below the lower limit position of the restriction portion.

In paddy field farming equipment, floats are often made by blow molding synthetic resin and are configured to have a relatively large contact area, so unevenness in the paddy field surface can cause the entire float to elastically deform and twist slightly.

As mentioned above, if the float swings upward while elastically deformed, it may reach the upper limit of the regulating mechanism before reaching the upper limit of the regulating part of the height detector, and the regulating mechanism may restrict the float at the upper limit. Similarly, if the float swings downward while elastically deformed, it may reach the lower limit of the regulating mechanism before reaching the lower limit of the regulating part of the height detector, and the regulating mechanism may restrict the float at the lower limit.
It is desirable for the height detection unit to detect the height over the entire range from the upper limit position to the lower limit position of the height detection unit's regulating part, so when the above-mentioned situation occurs, it becomes difficult for the height detection unit to detect the height over the entire range from the upper limit position to the lower limit position of the height detection unit's regulating part.

According to the present invention, the upper limit position of the regulating mechanism is set above the upper limit position of the regulating part of the height detection part, and the lower limit position of the regulating mechanism is set below the lower limit position of the regulating part of the height detection part.
As a result, even if the float elastically deforms, it is more likely to reach the upper limit position of the regulating part of the height detection unit before reaching the upper limit position of the regulating mechanism, and it is more likely to reach the lower limit position of the regulating part of the height detection unit before reaching the lower limit position of the regulating mechanism.Therefore, it becomes easier for the height detection unit to detect over the entire range spanning the upper limit position and lower limit position of the regulating part of the height detection unit, and a decrease in the detection performance of the height detection unit can be prevented.

According to the present invention, the height detection unit is provided on the right side of the portion of the float that is supported by the working device so that it can swing up and down, and the restriction mechanism is provided on the left side. Alternatively, the height detection unit is provided on the left side of the portion of the float that is supported by the working device so that it can swing up and down, and the restriction mechanism is provided on the right side.

As a result, when the float is supported on the work equipment so that it can swing up and down, the left and right balance of the float is good, allowing the float to swing up and down stably and follow the ground stably on the rice field surface, allowing the height detection unit to stably detect the height from the float to the work equipment.

In the present invention,
a body supported by wheels for running;
a working device supported at the rear of the machine body so as to be able to rise and fall;
a float supported on the lower part of the working device so as to be able to swing up and down and follow the ground contact with the rice field surface;
a height detection unit that detects the height of the working device from the float;
an elevation control unit that raises and lowers the working device relative to the machine body based on detection by the height detection unit so that the working device is maintained at a preset height from the rice field surface;
a restriction mechanism provided separately from the height detection unit and configured to restrict the float to at least one of an upper limit position and a lower limit position of up-and-down swing relative to the working device,
The height detection unit is preferably provided at the front of the float, and is provided forward of the restriction mechanism in a side view.

According to the present invention, the height detection portion is provided forward of the restriction mechanism in a side view.
As a result, the height detection unit and the regulating mechanism are located at different positions in the front-to-back direction relative to the float, which reduces interference between the height detection unit and the regulating mechanism, making the configuration to avoid interference between the height detection unit and the regulating mechanism unnecessary or small-scale, thereby simplifying the structure when installing the height detection unit and the regulating mechanism.

According to the present invention, for example, when the height detection unit is configured to extend upward from the float, the height detection unit is located forward of the restriction mechanism in side view, making it easier to extend the height detection unit upward from the float while avoiding the various parts of the work device.

In this invention, it is preferable that a fulcrum member is supported on the lower part of the working device along the left-right direction, and a support arm is connected to the fulcrum member and extends diagonally downward and rearward, the float is supported on the rear part of the support arm so that it can swing up and down around an axis along the left-right direction, the height detection unit is provided forward of the fulcrum member in a side view, and the restriction mechanism is provided rearward of the fulcrum member in a side view.

In paddy field working machines, a fulcrum member is supported at the bottom of the working device along the left-right direction, a support arm is connected to the fulcrum member and extends diagonally downward and rearward, and a float is sometimes configured to be supported at the rear of the support arm so that it can swing up and down around an axis along the left-right direction.

According to the present invention, in the above-described configuration, the height detection unit is provided forward of the fulcrum member in side view, and the restriction mechanism is provided rearward of the fulcrum member in side view, so that the fulcrum member is provided between the height detection unit and the restriction mechanism in side view. This allows the fulcrum member to be provided by effectively utilizing the space between the height detection unit and the restriction mechanism in side view, allowing the fulcrum member, height detection unit, and restriction mechanism to be provided compactly.

In the present invention, it is preferable that the height detection unit has a restriction unit that restricts at least one of the upper and lower limit positions of the float relative to the working device.

According to the present invention, for example, when the float is restricted at the upper limit position by the restriction mechanism, the restriction portion of the height detection unit restricts the float to at least one of the upper limit position and the lower limit position. For example, when the float is restricted at the lower limit position by the restriction mechanism, the restriction portion of the height detection unit restricts the float to either the upper limit position or the lower limit position.

According to the present invention, when the float is restricted at the upper limit position by the restricting portion and restricting mechanism of the height detector, the restriction at the upper limit position acts on multiple portions of the float.When the float is restricted at the lower limit position by the restricting portion and restricting mechanism of the height detector, the restriction at the lower limit position acts on multiple portions of the float.
The upper limit (lower limit) position of the float is regulated stably by restricting the float at the upper limit (lower limit) position on multiple portions of the float.

According to the present invention, for example, if the float is restricted at the upper limit position by the restricting portion of the height detection unit and restricted at the lower limit position by the restricting mechanism, or if the float is restricted at the lower limit position by the restricting portion of the height detection unit and restricted at the upper limit position by the restricting mechanism, the float is restricted at both the upper limit and the lower limit positions, preventing the float from swinging up and down significantly.

In the present invention, it is preferable that the height detection unit has a restriction unit that restricts the float at both the upper and lower limit positions relative to the working device, and that the restriction mechanism restricts the float at both the upper and lower limit positions of its up and down swing relative to the working device.

According to the present invention, the float is restricted at both the upper limit position and the lower limit position by the restricting portion and the restricting mechanism of the height detecting portion, so that the float is prevented from swinging up and down to a large extent.
According to the present invention, the float is restricted at its upper limit position by the restricting portion and restricting mechanism of the height detection portion, and the restriction at the upper limit position acts on multiple parts of the float.The float is restricted at its lower limit position by the restricting portion and restricting mechanism of the height detection portion, and the restriction at the lower limit position acts on multiple parts of the float.
By restricting a plurality of portions of the float at the upper limit position and restricting a plurality of portions of the float at the lower limit position, the float is stably restricted at the upper limit position and the lower limit position.

In the present invention, the regulating mechanism preferably includes a regulating pin supported by the working device, a regulating link supported by the float so as to be swingable around an axis extending in the left-right direction, and an elongated hole that opens along the longitudinal direction of the regulating link and into which the regulating pin is inserted. When the regulating pin reaches one end of the elongated hole, the float is regulated at the upper limit position of the regulating mechanism, and when the regulating pin reaches the other end of the elongated hole, the float is regulated at the lower limit position of the regulating mechanism.

According to the present invention, the restriction mechanism has a restriction pin and a restriction link with an elongated hole, and the restriction pin is inserted into the elongated hole, which simplifies the structure of the restriction mechanism.

In the present invention, it is preferable that the restriction mechanism has right and left support members supported by the working device, and that the restriction pin is attached across the right and left support members.

According to the present invention, the control pin is attached across the right and left support members supported by the work device, and is supported at both ends, thereby improving the support strength of the control pin.

In the present invention, the float preferably has a first portion supported on the working device so as to be able to swing up and down, and a second portion connected to the front of the first portion and having a width in the left-right direction greater than the width of the first portion, and the height detection unit is preferably provided on one of the right and left portions of the second portion, and the restriction mechanism is preferably provided on the other of the right and left portions of the second portion.

According to the present invention, in a float having a first portion with a small width and a second portion with a large width, a height detection unit is provided on one of the right and left portions of the second portion of the float, and a regulating mechanism is provided on the other of the right and left portions of the second portion of the float, making it easier to position the height detection unit and the regulating mechanism apart in the left-right direction from the float.
This further reduces interference between the height detection unit and the regulating mechanism, making the configuration to avoid interference between the height detection unit and the regulating mechanism unnecessary or small-scale, which is advantageous in terms of simplifying the structure when installing the height detection unit and the regulating mechanism.

In the present invention, the working device is a seedling planting device having a seedling tray on which seedlings are placed, a planting arm that removes the seedlings from the seedling tray and plants them in the rice field, and a planting transmission case that supports the planting arm on its side, and it is preferable that the planting transmission case be positioned in a position offset in the left-right direction from the position above the regulating mechanism.

According to the present invention, the working device is a seedling planting device, which is provided with a seedling tray on which the seedlings are placed, a planting arm that removes the seedlings from the seedling tray and plants them on the rice field surface, and a planting transmission case that supports the planting arm on its side.
In this case, since the regulating mechanism is located behind the height detection unit in a side view, the regulating mechanism and the planting transmission case may come close to each other in the front-to-back direction.

According to the present invention, the planting transmission case is positioned laterally away from the position above the regulating mechanism, which reduces interference between the regulating mechanism and the planting transmission case, allowing the regulating mechanism and the planting transmission case to be positioned comfortably.

FIG. 1 is a left side view of a riding rice transplanter. FIG. 2 is a plan view of the seedling planting device and the ground leveling device. FIG. 2 is a plan view showing the support structure for the center float and the side float. FIG. 2 is a front view of the vicinity of the center float. FIG. 2 is a left side view of the vicinity of the center float. FIG. 2 is a left side view of the vicinity of the center float. FIG. 2 is a left side view of the vicinity of the rear of the center float. FIG. 2 is a plan view of the vicinity of the rear of the center float. FIG. 2 is a left side view of the vicinity of the side float. FIG. 2 is a left side view of the vicinity of the side float. FIG. 2 is a plan view showing the support structure of the side float. FIG. 2 is a plan view of the center float. FIG. FIG. FIG. 2 is a left side view of the center float. FIG. 2 is a left side view showing the lifting structure of the ground leveling device. FIG. FIG. FIG. 2 is a schematic diagram showing the linkage between the control device and each part. FIG. 13 is a left side view of the vicinity of a side float in a seventh modified embodiment of the invention.

Figures 1 to 20 show a riding rice transplanter, an example of a paddy field working machine. In Figures 1 to 20, F indicates the forward direction, B indicates the backward direction, U indicates the upward direction, D indicates the downward direction, R indicates the rightward direction, and L indicates the leftward direction.

(Overall configuration of riding rice transplanter)
As shown in FIG. 1 , a machine body 3 is supported by right and left front wheels 1 (corresponding to wheels for driving) and right and left rear wheels 2 (corresponding to wheels for driving). A link mechanism 4 extends rearward from the rear of the machine body 3, and a seedling planting device 5 (corresponding to a working device) is supported at the rear of the link mechanism 4. A fertilizer applicator 6 is supported at the rear of the machine body 3, and a soil leveling device 30 is supported at the front of the seedling planting device 5. The link mechanism 4 is raised and lowered by extending and retracting a hydraulic cylinder 7, which in turn raises and lowers the seedling planting device 5. The hydraulic cylinder 7 is connected between the rear of the machine body 3 and the link mechanism 4. A driver's seat 8 and a steering handle 9 for steering the front wheels 1 are provided on the machine body 3. Right and left support frames 10 are connected to the right and left front portions of the machine body 3 and extend upward, and a spare seedling tray 11 is attached to the support frames 10.

(Overall configuration of seedling planting device)
As shown in Figures 1, 2, and 3, the seedling planting device 5 is configured as an eight-row planting device, and includes a feed case 12, a support frame 13, a planting transmission case 14, a rotating case 15, a planting arm 16, a center float 17 (corresponding to a float), side floats 18 and 19 (corresponding to floats), and a seedling tray 20. The feed case 12 is supported at its lower part by the rear of the link mechanism 4, and a square pipe-shaped support frame 13 is connected to the feed case 12 and extends in the left-right direction. Four planting transmission cases 14 are connected to the support frame 13 and extend rearward. The rotating case 15 is rotatably supported on the right and left rear of the planting transmission case 14, and a pair of planting arms 16 is attached to the rotating case 15. The seedling tray 20, on which the seedlings are placed, is supported by the planting transmission case 14 for reciprocating movement in the left-right direction. As the machine body 3 advances, the paddy field G (see FIG. 5 ) is leveled by the soil leveling device 30. In the seedling planting device 5, the seedling tray 20 is driven to reciprocate in the left-right direction, while the rotating case 15 is driven to rotate, and the planting arm 16 removes the seedlings from the seedling tray 20 and plants them in the paddy field G.

(Configuration of transmission system to rotating case in seedling planting device)
As shown in Fig. 2, power from an engine (not shown) mounted on the machine body 3 is transmitted via a transmission shaft 26 (see Fig. 1) to an input shaft 27 inside the feed case 12. An output shaft 28 is provided at the bottom of the feed case 12, and the power transmitted to the input shaft 27 is transmitted to the output shaft 28 via a transmission chain 29.

The power of the output shaft 28 of the feed case 12 is transmitted to the drive shaft 35 via the transmission shaft 32, input shaft 31, torque limiter 33, transmission chain 34, and few-thread clutch 36 housed inside the cylindrical cover 37, causing the drive shaft 35 to rotate, and the rotating case 15 and planting arm 16 to rotate counterclockwise in Figure 1.

(Overall configuration of the fertilizer application device)
1 and 3, the fertilizer application device 6 has a hopper 21, a delivery unit 22, a blower 23, a furrow former 24, and a hose 25. As the machine body 3 moves forward, fertilizer from the hopper 21 is delivered to the hose 25 by the delivery unit 22, air from the blower 23 is supplied to the hose 25, and the fertilizer is supplied to the furrow former 24 through the hose 25. As the machine body 3 moves forward, furrows are formed in the rice field surface G (see FIG. 5) by the furrow former 24, the fertilizer supplied to the furrow former 24 is then supplied from the furrow former 24 into the furrows in the rice field surface G, and the furrows in the rice field surface G are filled in with soil covering members 38.

(Configuration of Support Arm of Fulcrum Member)
As shown in Figures 3, 4, and 5, the seedling planting device 5 (working device) has a fulcrum member 41 supported on the lower part of the seedling planting device 5 (working device) in the left-right direction, several pairs of support arms 41a, 41b, 41c connected to the fulcrum member 41 and extending diagonally downward and rearward, and several center floats 17 (floats) and side floats 18, 19 (floats) supported on the rear parts of the pairs of support arms 41a, 41b, 41c so as to be able to swing up and down around an axis P2 that runs in the left-right direction and follow the ground contact with the rice field surface G.

As shown in Figure 3, the left-right distance W1 between the pair of support arms 41a of the fulcrum member 41, the left-right distance W2 between the pair of support arms 41b of the fulcrum member 41, and the left-right distance W3 between the pair of support arms 41c of the fulcrum member 41 are the same value, and the distance W3 is larger than the distances W1 and W2.

As shown in Figures 3, 7, 8, and 9, a flat plate-shaped first member 39 is connected to the upper surfaces of the support arms 41a and 41b of the fulcrum member 41 at the midpoint between the front and rear of the support arms 41a and 41b. A channel-shaped second member 40 is connected to the upper surfaces of the rear portions of the support arms 41a and 41b of the fulcrum member 41.

As shown in Figures 3, 10, and 11, a flat plate-shaped first member 39 is connected to the upper surface of the rear part of the support arm 41c of the fulcrum member 41.

The channel-shaped second member 40 is connected across the front-to-rear intermediate portion of the support arm 41c of the fulcrum member 41, with the open portion of the second member 40 facing forward. The second member 40 is connected across the lateral surface of the support arm 41c of the fulcrum member 41, and in side view, the second member 40 does not extend above or below the upper or lower end of the support arm 41c of the fulcrum member 41 (see Figure 10).

With the above configuration, as shown in Figure 3, the left-right spacing W1 between the pair of support arms 41a located in the left-right center of the seedling planting device 5 (working device) and the left-right spacing W3 between the pair of support arms 41c located on the right and left sides of the seedling planting device 5 (working device) are set to different values.

The left-right distance W3 between the pair of support arms 41c located on the right and left sides of the seedling planting device 5 (working device) is set to be greater than the left-right distance W1 between the pair of support arms 41a located in the left-right center of the seedling planting device 5 (working device).

As shown in Figures 10 and 11, a flat plate-shaped first member 39 is connected across the rear of the pair of support arms 41c of the fulcrum member 41, and a channel-shaped second member 40 is connected across the portions of the pair of support arms 41c of the fulcrum member 41 that are closer to the fulcrum member 41 than the first member 39. The second member 40 is connected across the lateral surfaces of the pair of support arms 41c of the fulcrum member 41.

(Center float configuration)-1
12 to 15, the center float 17 is manufactured by blow molding and has a first portion 91, which is the rear portion, and a second portion 92, which is the front portion. The right portion of the second portion 92 is located below the planting depth lever 42 and the guide portion 43 (see FIG. 4).

As shown in Figures 12 and 15, the center float 17 (float) has a first portion 91 supported on the lower part of the seedling planting device 5 (working device), and a second portion 92 connected to the front of the first portion 91 and extending diagonally forward and upward from the front of the first portion 91 in a side view.

The width W21 of the second portion 92 in the left-right direction is greater than twice (or three times) the width W11 of the first portion 91 in the left-right direction.
The width W22 in the left-right direction extending from the right end of the first part 91 to the right end of the second part 92 is larger than the width W11 in the left-right direction of the first part 91, and the width W23 in the left-right direction extending from the left end of the first part 91 to the left end of the second part 92 is larger than the width W11 in the left-right direction of the first part 91.
The length L2 of the second portion 92 in the front-rear direction is shorter than the length L of the first portion 91 in the front-rear direction.
As shown in Figure 4, the planting depth lever 42 (float position change part) is provided within the range of the width W21 in the left-right direction of the second part 92 when viewed from the front.

(Center float configuration)-2
12 to 15, in the center float 17, the upper surface 91a and the lower surface 91b of the first portion 91 are substantially parallel in side view. The upper surface 92a of the second portion 92 extends obliquely upward and forward in a substantially linear manner from the front portion of the upper surface 91a of the first portion 91 in side view.

In the second portion 92 of the center float 17, the underside 92b (corresponding to the first underside) of the second portion 92 extends forward in parallel from the front portion of the underside 91b of the first portion 91 in side view.

The connecting portion 92d of the second portion 92, which is arc-shaped in side view, extends diagonally upward and forward from the front portion of the underside portion 92b of the second portion 92 in side view. The underside portion 92c (corresponding to the second underside portion) of the second portion 92 extends diagonally upward and forward from the front portion (upper portion) of the connecting portion 92d of the second portion 92 in side view.

As shown in FIG. 15 , in a side view, the front-rising angle θ1 of the lower surface 92c of the second portion 92 relative to the lower surface 91b of the first portion 91 is greater than the front-rising angle θ2 of the upper surface 92a of the second portion 92 relative to the lower surface 91b of the first portion 91.

The upper surface portion 92a of the second portion 92 extends obliquely upward and forward from the front portion of the upper surface portion 91a of the first portion 91 in a side view.
In a side view, the lower surface portions 92b, 92c of the second part 92 have a first lower surface portion 92b extending parallel and forward from the lower surface portion 91b of the first part 91, and a second lower surface portion 92c extending diagonally forward and upward from the front of the first lower surface portion 92b.
In a side view, the front rising angle θ1 of the second lower surface portion 92c of the second portion 92 relative to the lower surface portion 91b of the first portion 91 is greater than the front rising angle θ2 of the upper surface portion 92a of the second portion 92 relative to the lower surface portion 91b of the first portion 91.

In the second part 92, the joint portion 90 (portion) corresponding to the mating portion of a pair of molds used in blow molding is located closer to the lower surface portions 92b and 92c of the second part 92 than the intermediate portion between the upper surface portion 92a of the second part 92 and the lower surface portions 92b and 92c of the second part 92 in a side view.

(Center float configuration)-3
As shown in Figures 12 to 15, in the center float 17, right and left recesses 93 that are recessed downward are provided on the upper surface 92a of the second portion 92, and right and left recesses 94 that are recessed upward are provided on the lower surface portions 92b, 92c and the connecting portion 92d of the second portion 92.

The furrow former 24 (see Figures 1, 3, and 4) of the fertilizer applicator 6 is attached to the recesses 93 and 94 of the center float 17, and the soil cover members 38 (see Figures 3, 7, and 8) are attached to the right and left portions of the first portion 91. A downwardly recessed recess 98 is provided on the right portion of the upper surface 92a of the second portion 92, and the recess 98 is connected to the right recess 93.

A downwardly recessed recess 95 is provided on the left side of the upper surface 92a of the second portion 92, and an upwardly recessed recess 96 is provided on the left side of the lower surface 92b and connecting portion 92d of the second portion 92.

Downwardly recessed recesses 97 (corresponding to upper recesses) are provided on the upper surface 92a of the second portion 92 between the right and left recesses 93 and on the right side of the right recess 93. The recesses 97 have an elongated shape extending in the front-to-rear direction in plan view.

As shown in Figures 12 and 15, a recess 97 (upper recess) extending from the upper surface 92a of the second portion 92 toward the lower surface portions 92b and 92c of the second portion 92 is provided on the upper surface 92a of the second portion 92. The recess 97 (upper recess) is formed along the front-to-rear direction, and its depth from the upper surface 92a of the second portion 92 becomes shallower toward the rear.

(Center float configuration)-4
As shown in Figures 4, 13, and 14, in the center float 17, upwardly recessed recesses 99 (corresponding to lower recesses) are provided on the lower surface portions 92b, 92c and the connecting portion 92d of the second portion 92, and an upwardly recessed recess 100 is provided on the lower surface portion 91b of the first portion 91.

The recess 100 is formed in the front-to-rear direction, extending from the rear of the recess 99 to the rear end of the underside 91b of the first section 91. The left-to-right width of the recess 100 is the same as the left-to-right width of the rear of the recess 99.

As shown in Figures 12 to 15, the joint portion 90 is formed by bending the upper surface 92a of the second portion 92 downward at the right side of the front end of the second portion 92, and an attachment portion 101 is provided on the joint portion 90, which extends below the upper surface 92a of the second portion 92.

As shown in Figures 4, 13, and 14, recesses 99 (lower recesses) are provided on the lower surfaces 92b and 92c of the second portion 92, extending from the lower surfaces 92b and 92c of the second portion 92 toward the upper surface 92a of the second portion 92. The recesses 99 (lower recesses) are formed along the front-to-rear direction, and the width of the recesses 99 (lower recesses) in the left-to-right direction increases toward the front.

As shown in Figures 12 to 15, an attachment portion 101 is provided at the front end of the second portion 92, extending below the upper surface portion 92a of the second portion 92 in a side view, and the height detection unit 50 is attached to the attachment portion 101.

(Configuration of attachment of fulcrum member to support arm in center float)-1
7 and 8, there is provided a mounting member 59 attached to the center float 17 (float). By attaching the mounting member 59 to the fulcrum shaft 63, the center float 17 (float) is supported by the rear parts of the pair of support arms 41a of the fulcrum member 41 so as to be able to swing up and down around the axis P2 via the fulcrum shaft 63.

The mounting member 59 is formed in a rectangular shape in a plan view and has a base portion 59a attached to the center float 17 (float), and right and left side portions 59b extending upward from the right and left portions of the base portion 59a and attached to the fulcrum shaft 63.

(Configuration of attachment of fulcrum member to support arm in center float)-2
5 and 6, a regulating mechanism 67 is attached across the fulcrum member 41 and the second portion 92 of the center float 17. The regulating mechanism 67 is provided on the left side of the planting transmission case 14 located above the center float 17, and the planting transmission case 14 located above the center float 17 is positioned to the right of the position above the regulating mechanism 67.

The restriction mechanism 67 has right and left support members 64, a restriction pin 65, and a restriction link 66. The right and left support members 64 are connected to a portion of the fulcrum member 41 located above the center float 17 and extend diagonally rearward and downward from the fulcrum member 41. A top plate portion (not shown) is connected to the upper parts of the right and left support members 64, and the restriction pin 65 is attached to the rear of the right and left lateral portions 64b of the support members 64.

A bracket 69 is attached to the recesses 95, 96 (see Figures 12 and 13) in the second portion 92 of the center float 17. The restriction link 66 is formed by bending a long, thin plate into a channel shape and is supported by the bracket 69 so that it can swing up and down around an axis P3 that runs in the left-right direction. A long hole 66a is opened along the longitudinal direction of the restriction link 66. Right and left support members 64 are positioned inside the restriction link 66, and a restriction pin 65 is inserted into the long hole 66a of the restriction link 66.

When the seedling planting device 5 descends relative to the center float 17 (when the center float 17 rises relative to the seedling planting device 5), the regulating link 66 swings downward. The regulating pin 65 hits the front end of the elongated hole 66a of the regulating link 66, stopping the center float 17 from rising relative to the seedling planting device 5 (this corresponds to a state in which the center float 17 is restricted at its upper limit position relative to the seedling planting device 5).

When the seedling planting device 5 rises relative to the center float 17 (when the center float 17 descends relative to the seedling planting device 5), the regulating link 66 swings upward. The regulating pin 65 hits the rear end of the elongated hole 66a of the regulating link 66, stopping the center float 17 from descending relative to the seedling planting device 5 (this corresponds to a state in which the center float 17 is restricted at its lowest position relative to the seedling planting device 5).

(Configuration of attachment of fulcrum member to support arm in side float)-1
10 and 11, the mounting member 60 is attached to the rear of the side float 19. The mounting member 60 has a base portion 60a formed in a rectangular shape in a plan view, and right and left lateral side portions 60b extending upward from the right and left portions of the base portion 60a.

The front end of the base plate portion 59a of the mounting member 60 extends forward from the front end of the lateral side portion 60b of the mounting member 60, and the length of the base plate portion 59a of the mounting member 60 in the front-to-rear direction is longer than the length of the lateral side portion 60b of the mounting member 60 in the front-to-rear direction. Two points on the front of the base plate portion 60a of the mounting member 60 are connected to the upper surface of the rear portion of the side float 19 by bolts 73.

The fulcrum shaft 63 is supported across the rear lateral surfaces of the support arms 41c of the fulcrum member 41. The right and left lateral sides 60b of the mounting member 60 are positioned between the support arms 41c of the fulcrum member 41, and are attached to the fulcrum shaft 63 so as to be able to swing up and down around the axis P2.

A coil spring 74 is attached to the fulcrum shaft 63, with one end 74a of the spring 74 abutting the rear of the base portion 60a of the mounting member 60. Multiple mounting holes 41d are formed in the support arm 41c of the fulcrum member 41, and the other end 74b of the spring 74 is inserted into the mounting holes 41d.

The end 74a of the spring 74 presses down on the rear of the side float 19, and the side float 19 is urged in a forward upward direction around the fulcrum shaft 63 (axis center P2). By inserting the end 74b of the spring 74 into another mounting hole 41d of the support arm 41c of the fulcrum member 41, the urging force of the spring 74 can be changed.
As shown in FIG. 9, the side float 18 also has a fulcrum shaft 63, a mounting member 60, and a spring 74 similar to those of the side float 19.

(Configuration of attachment of fulcrum member to support arm in side float)-2
9, 10, and 11, a restriction pin 75 is attached across the lateral surface of the support arm 41b of the fulcrum member 41 and across the lateral surface of the support arm 41c of the fulcrum member 41. A stopper portion 41e is attached to the fulcrum member 41 at a portion located above the side floats 18, 19.

Bracket 76 is attached to side floats 18, 19, and restriction link 77 is supported by bracket 76 so that it can swing up and down around axis P7 along the left-right direction. An elongated hole 77a is opened along the longitudinal direction of restriction link 77, and restriction pin 75 is inserted into elongated hole 77a of restriction link 77.

When the seedling planting device 5 descends relative to the side floats 18, 19 (when the side floats 18, 19 rise relative to the seedling planting device 5), the front of the side floats 18, 19 hits the stopper portion 41e of the fulcrum member 41, stopping the side floats 18, 19 from rising relative to the seedling planting device 5 (this corresponds to a state in which the side floats 18, 19 are restricted at their upper limit position relative to the seedling planting device 5).

When the seedling planting device 5 rises relative to the side floats 18, 19 (when the side floats 18, 19 descend relative to the seedling planting device 5), the restricting link 77 swings upward. The restricting pin 75 hits the rear end of the elongated hole 77a of the restricting link 77, preventing the side floats 18, 19 from descending relative to the seedling planting device 5 (this corresponds to a state in which the side floats 18, 19 are restricted at their lowest position relative to the seedling planting device 5).

(Configuration of planting depth lever)
As shown in Figures 3, 4, and 8, a manually operable planting depth lever 42 (corresponding to the float position changer) (corresponding to the height adjuster) is connected to the fulcrum member 41 and extends diagonally forward and upward. The planting depth lever 42 is provided on the right side of the link mechanism 4 (see Figure 1), and is provided above the right part of the second part 92 of the center float 17, which will be described later.

The guide portion 43 is connected to the support frame 13 and is located on the right side of the link mechanism 4 (see Figure 1). The planting depth lever 42 is inserted into and guided by the guide portion 43, and by engaging the planting depth lever 42 with the guide portion 43, the planting depth lever 42 is held at any position by the guide portion 43. By engaging the planting depth lever 42 with the guide portion 43, the position of the axis P2 can be fixed and the seedling set depth B1 can be set.

(Configuration of guide part)
17 and 18, the guide portion 43 has a main body portion 44 and an engaging member 45 (corresponding to a reinforcing member). The main body portion 44 is configured by bending a flat plate into a channel shape, and openings 44b and 44c are formed on an upper surface portion 44a (corresponding to a reinforcing member) of the main body portion 44.

The opening 44b of the main body 44 is rectangular in plan view. The engaging member 45 is flat and has a thickness greater than that of the top surface 44a of the main body 44. A rectangular opening 45a is formed in the engaging member 45, and multiple protruding engaging portions 45b are provided on the right side of the opening 45a.

The planting depth lever 42 is inserted into the openings 44b, 45a of the guide portion 43 (main body portion 44 and engaging member 45) and guided along the openings 44b, 45a of the guide portion 43 (main body portion 44 and engaging member 45). The planting depth lever 42 is held in place by engaging the engaging portion 45b of the guide portion 43 (engaging member 45). Engaging the planting depth lever 42 with the guide portion 43 fixes the position of the axis P2, allowing the seedlings to be set at a set depth B1.

The opening 44c of the main body 44 is formed in a rectangular shape in a plan view, and a large number of protruding engaging portions 44d are provided on the left side of the opening 44c of the main body 44.
The seedling removal amount lever 46 is inserted into the opening 44c of the guide part 43 (main body part 44) and guided along the opening 44c of the guide part 43 (main body part 44). The seedling removal amount lever 46 is held in the guide part 43 by engaging with the engaging part 44d of the guide part 43 (main body part 44).

With the above configuration, as shown in Figures 17 and 18, a reinforcing member (the upper surface 44a of the main body 44 and the engaging member 45) is provided at the portion (engaging portion 45b) of the guide portion 43 where the planting depth lever 42 (height adjuster) engages. By providing a reinforcing member in this way, strength can be maintained even when the number of engaging portions 45b is increased. Therefore, while using a guide portion 43 of approximately the same size as conventional guide portions, the number of engaging portions 45b can be increased to allow for finer planting depth adjustment.

(Configuration for controlling the lifting and lowering of the seedling planting device)
As shown in FIGS. 4, 5 and 6, a height detection unit 50 is provided to detect the height from the center float 17 (float).

The height detection unit 50 is provided in front of the restriction mechanism 67 in a side view.
It is equipped with a fulcrum member 41 supported on the bottom of the seedling planting device 5 (working device) along the left-right direction, and a support arm 41a connected to the fulcrum member 41 and extending diagonally downward and rearward, and the center float 17 (float) is supported at the rear of the support arm 41a of the fulcrum member 41 so that it can swing up and down around an axis P2 along the left-right direction.
The height detection unit 50 is provided in front of the fulcrum member 41 in a side view, and the restriction mechanism 67 is provided behind the fulcrum member 41 in a side view.

The height detection unit 50 has a regulating unit 48 that regulates at least one of the upper limit position and the lower limit position of the center float 17 (float) relative to the seedling planting device 5 (working device).
The height detection unit 50 has a regulating unit 48 that regulates the center float 17 (float) at both the upper and lower limit positions relative to the seedling planting device 5 (working device).

(Seedling planting device lift control)-1
19, a lift control unit 71 as software is provided in the control device 70. A control valve 49 is provided which supplies and discharges hydraulic oil to and from the hydraulic cylinder 7 (see FIG. 1) to cause the hydraulic cylinder 7 to expand and contract, and the control valve 49 is operated by the lift control unit 71.

The state shown in Figure 5 is when the planting depth lever 42 is operated to its forward-most position relative to the guide portion 43, the axis P2 of the center float 17 and side floats 18, 19 is at its highest position relative to the seedling planting device 5, and the seedling setting depth B1 is set to its deepest position.

The state shown in Figure 6 is when the planting depth lever 42 is operated to its rearmost position relative to the guide portion 43, the axis P2 of the center float 17 and side floats 18, 19 is at its lowest position relative to the seedling planting device 5, and the seedling setting depth B1 is set to its shallowest position.

As shown in Figures 5, 6, and 19, the height from the rice field surface G (center float 17) to the height sensor 68 (detection axis 68a) is set as the set height A1 in the control device 70 (lift control unit 71). When the height from the rice field surface G (center float 17) to the height sensor 68 (detection axis 68a) is set to the set height A1, the detection arm 54 (detection value of the height sensor 68) is in the neutral position C1.

When the planting depth lever 42 is operated forward relative to the guide part 43 (towards the deeper side of the set seedling depth B1), the linkage rod 58 is operated forward, and the support member 53 is operated upward by the first link 51 and second link 52, so that the height from the rice field surface G (center float 17) to the height sensor 68 (detection axis 68a) is maintained at the set height A1.

When the planting depth lever 42 is operated backward relative to the guide part 43 (towards the shallower side of the set seedling depth B1), the linkage rod 58 is operated backward, and the support member 53 is operated downward by the first link 51 and second link 52, so that the height from the rice field surface G (center float 17) to the height sensor 68 (detection axis 68a) is maintained at the set height A1.

(Seedling planting device lift control)-2
As shown in Figures 5, 6 and 19, when the seedling planting device 5 moves up and down relative to the center float 17 which follows the ground on the rice field surface G, the detection arm 54 (detection value of the height sensor 68) moves upward (downward) from the neutral position C1, so the lifting control unit 71 operates the control valve 49 and the seedling planting device 5 is raised and lowered by the hydraulic cylinder 7 so that the detection arm 54 (detection value of the height sensor 68) returns to the neutral position C1.

By raising and lowering the seedling planting device 5 so that the detection arm 54 (detection value of the height sensor 68) is in the neutral position C1, the height from the rice field surface G (center float 17) to the height sensor 68 (detection axis 68a) is maintained at the set height A1, and the seedling planting depth by the planting arm 16 is maintained at the set depth B1.

(Relationship between the height detection unit and the restriction mechanism)-1
The relationship between the regulating portion 48 of the height detecting portion 50 and the regulating mechanism 67 of the center float 17 will be described below.

As shown in Figures 5 and 6, when the height from the rice field surface G (center float 17) to the height sensor 68 (detection axis 68a) is the set height A1 and the detection arm 54 (detection value of the height sensor 68) is in the neutral position C1 (see Figure 19), the regulating pin 65 in the regulating mechanism 67 is located in the front-to-rear middle of the elongated hole 66a of the regulating link 66.

When the seedling planting device 5 descends relative to the center float 17 (when the center float 17 rises relative to the seedling planting device 5), the front of the detection arm 54 hits the front end of the regulating part 48, and the height detection part 50 on the center float 17 is regulated at the upper limit position of the height detection part 50.

When the height detection unit 50 of the center float 17 is restricted at its upper limit position, the restriction pin 65 of the restriction mechanism 67 has not reached the front end of the elongated hole 66a of the restriction link 66, and the restriction mechanism 67 part of the center float 17 can still rise.

If the regulating mechanism 67 portion of the center float 17 rises further due to twisting of the center float 17, the regulating pin 65 of the regulating mechanism 67 will hit the front end of the elongated hole 66a of the regulating link 66, and the regulating mechanism 67 portion of the center float 17 will be restricted to the upper limit position of the regulating mechanism 67.

When the seedling planting device 5 rises relative to the center float 17 (when the center float 17 descends relative to the seedling planting device 5), the rear of the detection arm 54 hits the rear end of the regulating part 48, and the part of the center float 17 near the height detection part 50 is regulated at the lower limit position of the height detection part 50.

When the height detection unit 50 of the center float 17 is restricted at its lowest position, the restriction pin 65 of the restriction mechanism 67 has not reached the rear end of the elongated hole 66a of the restriction link 66, and the restriction mechanism 67 part of the center float 17 can still descend.

If the regulating mechanism 67 portion of the center float 17 further descends due to twisting of the center float 17, the regulating pin 65 of the regulating mechanism 67 will hit the rear end of the elongated hole 66a of the regulating link 66, and the regulating mechanism 67 portion of the center float 17 will be restricted to the lowest position of the regulating mechanism 67.

(Relationship between the height detection unit and the restriction mechanism)-2
With the above configuration, as shown in Figures 5 and 6, the upper limit position of the regulating mechanism 67 is set above the upper limit position of the regulating section 48 of the height detection section 50, and the lower limit position of the regulating mechanism 67 is set below the lower limit position of the regulating section 48 of the height detection section 50.

The height detection unit 50 is located on either the right or left side of the part of the center float 17 (float) that is supported so as to be able to swing up and down on the seedling planting device 5 (working device) (the part of the mounting member 59).

The regulating mechanism 67 is provided on the other of the right and left sides of the portion of the center float 17 (float) that is supported on the seedling planting device 5 (working device) so that it can swing up and down (the mounting member 59 portion).

As shown in Figure 12, the center float 17 (float) has a first part 91 that is supported on the seedling planting device 5 (working device) so that it can swing up and down, and a second part 92 that is connected to the front of the first part 91 and has a left-right width W21 that is greater than the left-right width W11 of the first part 91.

4, the height detection unit 50 is provided on one of the right and left portions of the second portion 92. The restriction mechanism 67 is provided on the other of the right and left portions of the second portion 92.
The planting transmission case 14 is positioned at a position offset to the left and right from the position above the regulating mechanism 67.

(Overall configuration of ground leveling device)
As shown in FIGS. 1 and 2, a soil leveling device 30 is supported at the front of the seedling planting device 5 and is disposed behind the rear wheels 2.
As shown in FIGS. 2 and 16, the ground leveling device 30 has a transmission case 80, a support frame 81, a drive shaft 82, ground leveling rotors 83 and 84, a support frame 85, and a cover 86.

The support case 78 is connected to the planting transmission case 14 at the left end, and the support bracket 79 is connected to the right end of the support frame 13. The transmission case 80 is supported by the support case 78 so as to be able to swing up and down around the axis P8 of the input shaft 31 and the transmission shaft 32, and extends diagonally forward and downward. The support frame 81 is supported by the support bracket 79 so as to be able to swing up and down around the axis P8, and extends diagonally forward and downward.

The drive shaft 82 is supported across the transmission case 80 and the front of the support frame 81 so as to be rotatable around a center axis P9 that runs in the left-right direction. Multiple rotating bodies 83 are attached to the center of the drive shaft 82 in the left-right direction so as to be positioned in front of the center float 17. Multiple rotating bodies 84 are attached to the right and left ends of the drive shaft 82 so as to be positioned in front of the side floats 18 and 19.

A round pipe-shaped support frame 85 is connected between the transmission case 80 and the support frame 81. A sheet metal cover 86 is connected to the support frame 85 and is located behind the rotors 83 and 84.

The transmission shaft 87 is supported throughout the support case 78 and the interior of the transmission case 80, and is connected to the input shaft 31 of the planting transmission case 14 at the left end. Inside the transmission case 80, a transmission chain 88 is attached between a sprocket on the transmission shaft 87 and a sprocket on the drive shaft 82, and a torque limiter 89 is installed between the sprocket on the transmission shaft 87.

Power transmitted to the input shaft 31 of the planting transmission case 14 at the left end is transmitted to the drive shaft 82 via the transmission shaft 87, torque limiter 89, and transmission chain 88, causing the drive shaft 82 and rotors 83 and 84 to rotate counterclockwise in the figure. By rotating the rotors 83 and 84 counterclockwise in Figure 16, the rice field surface G is leveled, and mud thrown backward from the rotors 83 and 84 is stopped by the cover 86.

(Configuration of lifting and lowering of ground leveling device)
As shown in Figures 4 and 16, the ground leveling lifting mechanism 105 (corresponding to the ground leveling device position changing unit) is provided across the support frame 13 and the ground leveling device 30, on the left side of the link mechanism 4 (see Figure 1), and above the left part of the second part 92 of the center float 17. The ground leveling lifting mechanism 105 includes a support frame 106, a lifting gear 107, a gear mechanism 108, an electric motor 109, and a connecting member 110. The lifting gear 107 is supported by the support frame 106 so as to be swingable up and down about an axis P10 extending in the left-right direction. A gear mechanism 108 equipped with a pinion gear 108a and the electric motor 109 that drives the gear mechanism 108 are attached to the upper part of the support frame 106, and the pinion gear 108a is engaged with the lifting gear 107.

The connecting member 110 is attached to the drive shaft 82 of the soil leveling device 30 via a bearing, and the upper part of the connecting member 110 is connected to the lifting gear 107. When the pinion gear 108a of the gear mechanism 108 is driven to rotate forward and backward by the electric motor 109, the lifting gear 107 is swung up and down around the axis P10, and the support position of the soil leveling device 30 on the seedling planting device 5 is changed up and down via the connecting member 110. The soil leveling lifting mechanism 105 (soil leveling device position change unit) is located within the range of the left-right width W21 of the second part 92 of the center float 17 when viewed from the front.

(Configuration of height adjustment of ground leveling device)
16 and 19, a height sensor 111 is provided to detect the angle of the lifting gear 107 relative to the support frame 106, and the detection value of the height sensor 111 is input to the control device 70. The height sensor 111 detects the angle of the lifting gear 107 relative to the support frame 106, thereby detecting the height of the soil leveling device 30 relative to the seedling planting device 5.

A planting depth sensor 113 is provided to detect the operating position of the planting depth lever 42. The detected value of the planting depth sensor 113 is input to the control device 70, and the set seedling depth B1 (see Figures 5 and 6) is detected based on the operating position of the planting depth lever 42.

A manually operable height adjustment switch 112 is provided near the control handle 9 (see FIG. 1), and an operation signal from the height adjustment switch 112 is input to the control device 70.
The height adjustment switch 112 sets and changes the leveling set height A2 (leveling depth), which is the height from the rice field surface G to the leveling device 30 (drive shaft 82).

A ground leveling lifting control unit 72 (software) is provided in the control device 70. Based on the operation signal of the height adjustment switch 112, the detection value of the height sensor 111, and the detection value of the planting depth sensor 113, the ground leveling lifting control unit 72 operates the electric motor 109 to change the support position of the ground leveling device 30 in the seedling planting device 5 up or down, as explained below.

The set seedling depth B1 (see Figures 5 and 6) is detected by the detection value of the planting depth sensor 113, and the height of the soil leveling device 30 relative to the seedling planting device 5 is detected by the height sensor 111, thereby detecting the height from the rice field surface G to the soil leveling device 30 (drive shaft 82).

The electric motor 109 operates to change the support position of the soil leveling device 30 in the seedling planting device 5 up or down so that the height from the rice field surface G to the soil leveling device 30 (drive shaft 82) becomes the soil leveling set height A2 (soil leveling depth) set (changed) by the height adjustment switch 112.

When the planting depth lever 42 is operated to change the seedling set depth B1 (see Figures 5 and 6), the height from the rice field surface G to the soil leveling device 30 (drive shaft 82) is detected based on the detection value of the planting depth sensor 113 and the detection value of the height sensor 111.

As described above, the electric motor 109 operates to change the support position of the soil leveling device 30 in the seedling planting device 5 up or down so that the height from the rice field surface G to the soil leveling device 30 (drive shaft 82) becomes the soil leveling set height A2 (soil leveling depth) set (changed) by the height adjustment switch 112.

As a result, even if the planting depth lever 42 is operated to change the seedling set depth B1 (see Figures 5 and 6), the height from the rice field surface G to the soil leveling device 30 (drive shaft 82) is maintained at the soil leveling set height A2 (soil leveling depth) set (changed) by the height adjustment switch 112.

(First Alternative Embodiment of the Invention)
The recesses 97 and 98 may be eliminated from the upper surface 92a of the second portion 92 of the center float 17.
In the undersides 92b, 92c and the connecting portion 92d of the second portion 92 of the center float 17, instead of the recess 99 whose width in the left-right direction increases toward the front, the recess 99 may have the same width in the left-right direction at the front and the rear, similar to the recess 100.

(Second Alternative Embodiment of the Invention)
In the center float 17, the widths W22 and W23 shown in FIG. 12 may be set slightly smaller than the width W11, so that the width W21 is greater than twice the width W11 and less than three times the width W11.
The length L2 may be configured to be longer than the length L1.

(Third Alternative Embodiment of the Invention)
The configuration of the center float 17 shown in Figures 12 to 15 may be adopted for the side floats 18, 19. In this case, the configurations described in the above (First Alternative Embodiment of the Invention) (Second Alternative Embodiment of the Invention) may be adopted for the side floats 18, 19.

(Fourth Alternative Embodiment of the Invention)
As described above (second alternative embodiment of the invention), in the center float 17, if the width W21 shown in Figure 12 is greater than twice the width W11 and less than three times the width W11, the planting depth lever 42 (float position change part) may be arranged outside the range of the width W21 in the left-right direction of the second part 92 when viewed from the front.

Similarly, the ground leveling lifting mechanism 105 (ground leveling device position changing unit) may be provided outside the range of the width W21 in the left-right direction of the second portion 92 of the center float 17 when viewed from the front.
The height detection unit 50 may be provided outside the range of the width W21 in the left-right direction of the second portion 92 of the center float 17 when viewed from the front.

(Fifth Alternative Embodiment of the Invention)
In the support arms 41a, 41b, and 41c of the fulcrum member 41 shown in FIG. 3, the distance W1 and the distance W2 may be the same value, and the distance W3 may be smaller than the distances W1 and W2.

The intervals W1, W2, and W3 may be different from one another. In this case, the values of the intervals W1, W2, and W3 may be set so as to satisfy the following relational expressions (1) to (4).
(1) Spacing W1 > Spacing W2 > Spacing W3
(2) Distance W1 < Distance W2 < Distance W3
(3) Spacing W1 > Spacing W2 = Spacing W3
(4) Interval W1 < Interval W2 = Interval W3

(Sixth Alternative Embodiment of the Invention)
In the support arms 41a, 41b of the fulcrum member 41, similar to the support arm 41c of the fulcrum member 41 shown in Figures 10 and 11, the first member 39 may be connected across the rear of the support arms 41a, 41b of the fulcrum member 41, and the second member 40 may be connected across the portion of the support arms 41a, 41b of the fulcrum member 41 that is closer to the fulcrum member 41 than the first member 39.
The second member 40 may be connected across the lateral surfaces of the support arms 41 a and 41 b of the fulcrum member 41 .

(Seventh Alternative Embodiment of the Invention)
When the second member 40 is connected across the lateral surfaces of the support arms 41b, 41c of the fulcrum member 41, the open portion of the second member 40 may be configured to face rearward, as shown in Figure 20.
With the above configuration, the open portion of the second member 40 faces rearward.

When the second member 40 is connected across the lateral surface of the support arm 41a of the fulcrum member 41, the open portion of the second member 40 may be configured to face rearward, as shown in Figure 20.

When the second member 40 is connected across the lateral surfaces of the support arms 41a, 41b, and 41c of the fulcrum member 41, the open portion of the second member 40 may be configured to face downward.

(Eighth Alternative Embodiment of the Invention)
5 and 6, the restricting unit 48 of the height detecting unit 50 may have an upper limit position and eliminate the lower limit position, or may have a lower limit position and eliminate the upper limit position. The restricting mechanism 67 may have an upper limit position and eliminate the lower limit position, or may have a lower limit position and eliminate the upper limit position.

The above-described configuration may be configured to have the following combinations (1) to (6).
(1) An upper limit position is provided and a lower limit position is eliminated in the regulating portion 48 of the height detecting portion 50. An upper limit position is provided and a lower limit position is eliminated in the regulating mechanism 67.
(2) The upper limit position is eliminated and a lower limit position is provided in the regulating portion 48 of the height detecting portion 50. The upper limit position is eliminated and a lower limit position is provided in the regulating mechanism 67.
(3) An upper limit position is provided and a lower limit position is eliminated in the regulating portion 48 of the height detecting portion 50. An upper limit position is eliminated and a lower limit position is provided in the regulating mechanism 67.
(4) The upper limit position is eliminated and a lower limit position is provided in the regulating portion 48 of the height detecting portion 50. The upper limit position is provided in the regulating mechanism 67 and the lower limit position is eliminated.
(5) Either an upper limit position or a lower limit position is provided in the restricting portion 48 of the height detecting unit 50. Both an upper limit position and a lower limit position are provided in the restricting mechanism 67.
(6) The restricting portion 48 of the height detecting portion 50 has both an upper limit position and a lower limit position. The restricting mechanism 67 has either an upper limit position or a lower limit position.

(Ninth Alternative Embodiment of the Invention)
In the height detection unit 50 and the restriction mechanism 67 , the height detection unit 50 may be provided on the left side of the second portion 92 of the center float 17 , and the restriction mechanism 67 may be provided on the right side of the second portion 92 of the center float 17 .

(Tenth Alternative Embodiment of the Invention)
In the seedling planting device 5, the rotating case 15 may be eliminated, and one planting arm 16 may be rotatably supported on the right side of the planting transmission case 14, and one planting arm 16 may be rotatably supported on the left side of the planting transmission case 14.
Instead of the seedling planting device 5, a sowing device (not shown) that supplies rice seeds to the rice field surface G may be provided as a working device.

The present invention can be applied to a paddy field working machine in which a work device such as a seedling planting device or sowing device is supported at the rear of the machine body, which is supported by wheels for running, and can be raised and lowered.

1. Front wheel (wheel)
2 Rear wheel (wheel)
3 Machine body 5 Seedling planting device (working device)
17 Center float (float)
30 Ground leveling device 42 Planting depth lever (float position change part)
50 Height detection unit 71 Lifting control unit 90 Connection part (part)
91 First portion 91b Lower surface portion 92 Second portion 92a Upper surface portion 92b Lower surface portion 92c Lower surface portion 97 Recessed portion (upper recessed portion)
99 Concave portion (lower concave portion)
101 Mounting part 105 Ground leveling device position change part A1 Set height G Paddy field surface L1 Length L2 Length W11 Width W21 Width W22 Width W23 Width θ1 Front rise angle θ2 Front rise angle

Claims (8)

a body supported by wheels for running;
a working device supported at the rear of the machine body so as to be able to rise and fall;
a float supported on the lower part of the working device so as to be able to swing up and down and follow the ground contact with the rice field surface;
a height detection unit that detects the height of the working device from the float;
an elevation control unit that raises and lowers the working device relative to the machine body based on detection by the height detection unit so that the working device is maintained at a preset height from the rice field surface;
a restriction mechanism provided separately from the height detection unit and configured to restrict the float to at least one of an upper limit position and a lower limit position of up-and-down swing relative to the working device ,
the height detection unit is provided on one of the right and left sides of a portion of the float that is supported by the working device so as to be able to swing up and down,
The regulating mechanism is provided on the other of the right and left parts of the float that is supported on the working device so as to be able to swing up and down . the float has a first portion supported on the working device so as to be able to swing up and down, and a second portion connected to a front portion of the first portion and having a width in the left-right direction greater than the width of the first portion in the left-right direction,
the height detection unit is provided on one of the right and left portions of the second portion,
The paddy field working machine according to claim 1 , wherein the regulating mechanism is provided on the other of the right and left portions of the second portion. a body supported by wheels for running;
a working device supported at the rear of the machine body so as to be able to rise and fall;
a float supported on the lower part of the working device so as to be able to swing up and down and follow the ground contact with the rice field surface;
a height detection unit that detects the height of the working device from the float;
an elevation control unit that raises and lowers the work device relative to the machine body based on detection by the height detection unit so that the work device is maintained at a preset height from the rice field surface;
a restriction mechanism that is provided separately from the height detection unit and that restricts the float to at least one of an upper limit position and a lower limit position of up-and-down swing relative to the working device,
The paddy field working machine according to claim 1 or 2 , wherein the height detection unit is provided at a front portion of the float, and is provided forward of the regulating mechanism in a side view. a fulcrum member supported on a lower portion of the working device along the left-right direction, and a support arm connected to the fulcrum member and extending diagonally downward and rearward,
The float is supported at the rear portion of the support arm so as to be able to swing up and down around an axis along the left-right direction,
the height detection unit is provided forward of the fulcrum member in a side view,
The paddy field working machine according to claim 3, wherein the restriction mechanism is provided rearward of the fulcrum member in a side view. a body supported by wheels for running;
a working device supported at the rear of the machine body so as to be able to rise and fall;
a float supported on the lower part of the working device so as to be able to swing up and down and follow the ground contact with the rice field surface;
a height detection unit that detects the height of the working device from the float;
an elevation control unit that raises and lowers the working device relative to the machine body based on detection by the height detection unit so that the working device is maintained at a preset height from the rice field surface;
a restriction mechanism provided separately from the height detection unit and configured to restrict the float to at least one of an upper limit position and a lower limit position of up-and-down swing relative to the working device,
the height detection unit has a restriction unit that restricts the float to one or both of an upper limit position and a lower limit position relative to the working device,
the regulating mechanism regulates the float to both an upper limit position and a lower limit position of up-and-down swing relative to the working device,
the regulating mechanism includes a regulating pin supported by the working device, a regulating link supported by the float so as to be swingable about an axis along the left-right direction, and a long hole that opens along the longitudinal direction of the regulating link and into which the regulating pin is inserted,
When the restriction pin reaches one end of the elongated hole, the float is restricted at the upper limit position of the restriction mechanism,
When the regulating pin reaches the other end of the elongated hole, the float is regulated at the lower limit position of the regulating mechanism. the restriction mechanism has right and left support members supported by the working device,
6. The paddy field working machine according to claim 5 , wherein the regulating pin is attached across the right and left support members. a body supported by wheels for running;
a working device supported at the rear of the machine body so as to be able to rise and fall;
a float supported on the lower part of the working device so as to be able to swing up and down and follow the ground contact with the rice field surface;
a height detection unit that detects the height of the working device from the float;
an elevation control unit that raises and lowers the working device relative to the machine body based on detection by the height detection unit so that the working device is maintained at a preset height from the rice field surface;
a restriction mechanism provided separately from the height detection unit and configured to restrict the float to at least one of an upper limit position and a lower limit position of up-and-down swing relative to the working device,
the height detection unit has a restriction unit that restricts the float to one or both of an upper limit position and a lower limit position relative to the working device,
the regulating mechanism regulates the float to both an upper limit position and a lower limit position of up-and-down swing relative to the working device,
A paddy field working machine in which the upper limit position of the regulating mechanism is set above the upper limit position of the regulating part, and the lower limit position of the regulating mechanism is set below the lower limit position of the regulating part. The working device is a seedling planting device having a seedling tray on which seedlings are placed, a planting arm that removes the seedlings from the seedling tray and plants them on the rice field surface, and a planting transmission case that supports the planting arm on its side.
The paddy field working machine according to claim 1 , wherein the planting transmission case is disposed at a position offset in the left-right direction from a position above the regulating mechanism.