Work vehicles

Abstract

To make a moving work vehicle traveling in plant cultivation facility perform entry positioning to an adjacent working passage easily and efficiently.SOLUTION: In a working vehicle that travels on each working passage 9 between a large number of cultivation beds 5 and a moving passage 4 leading to each working passage 9 at an end part of the cultivation beds 5, a bearing ring 20b traveling on a pair of right / left rails 13 arranged on each working passage 9 and wheels 20a traveling on the moving passage 4 are provided for a traveling vehicle body 21, and the wheels (20a, 20b) are capable of turning directions by wheel turning means (M), working passage entry position detection sensors 33, 37L, 37R, 40L, 40R which detect the rails 13 are provided for a side opposing to the rails 13 of the traveling vehicle body 21, and the working passage entry position detection sensors (33, 37L, 37R, 40L,40R) stop the working vehicle body 21 when a working passage entry position is detected when traveling on the moving passage 4.SELECTED DRAWING: Figure 6

Description

[Technical field]

[0001] The present invention relates to a work vehicle, such as a transport vehicle, that transports storage buckets for storing harvested crops in a plant cultivation facility. [Background technology]

[0002] In a plant cultivation facility, there is a configuration of a traveling device that performs work traveling in a work passage along a crop cultivation row and travel traveling in a travel passage that leads to a work passage along another crop cultivation row (Patent Document 1) [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2017-163928 A Summary of the Invention [Problem to be solved by the invention]

[0004] According to Patent Document 1, when the control device determines that the work vehicle has left the work aisle, the outside of the left and right running wheels are rotated forward and the inside of the turning wheel is rotated in the reverse direction, causing the running body to turn on the spot, which has the advantage of reducing the turning radius.

[0005] However, since the traveling vehicle body turns, it is difficult to align the entry position into the next adjacent work passage.

[0006] In view of the above, an object of the present invention is to easily and efficiently align an entry position into an adjacent working passage. [Means for solving the problem]

[0007] The first aspect of the present invention is In a work vehicle traveling on each of the work passages (9) between a large number of cultivation beds (5) and a moving passage (4) leading to each of the work passages (9) at the end of the cultivation beds (5), a traveling body (21) is provided with raceways (20b) that travel on a pair of left and right rails (13) arranged on each of the work passages (9) and wheels (20a) that travel on the moving passage (4), and the wheels (20a, 20b) are rotatable by a wheel turning means (M). A work passage entry position detection sensor (33, 37L, 37R, 40L, 40R) that detects the rail (13) is provided on the side of the traveling body (21) facing the rail (13), and when the work passage entry position detection sensor (33, 37L, 37R, 40L, 40R) detects the work passage entry position while traveling on the moving passage (4), the traveling body (21) is stopped, a sensor arm (34) protruding forward from the front side of the traveling body (21) is provided with a work passage entry position detection sensor (33, 37L, 37R, 40L, 40R); The work vehicle is provided with extension / retraction means (42, 43) for setting the sensor arm (34) in a forward protruding state and a retracted state relative to the traveling body (21), and is configured so that the sensor arm (34) is extended to the protruding state while traveling on the travel passage (4) and is shortened to the retracted state while traveling on the work passage (9). The second aspect of the present invention is In the first work vehicle of the present invention, the work passage entry position detection sensors (40L, 40R) are proximity sensor type sensors. The third aspect of the present invention is The rail (13) is a hot water pipe having a rail end (13t) that is connected in a U-shape at the starting end of the work passage (9), and the sensor arm (34) is provided with a contact prevention detection sensor (39, 41) that detects the rail end (13t).This is a work vehicle of the first or second invention. The first invention related to the present invention In a work vehicle that travels on each of the work passages (9) between a number of cultivation beds (5) and on a moving passage (4) that leads to each of the work passages (9) at the end of each of the cultivation beds (5), a traveling body (21) is provided with raceways (20b) that travel on a pair of left and right rails (13) arranged on each of the work passages (9) and wheels (20a) that travel on the moving passage (4), and the wheels (20a, 20b) can be turned by a wheel turning means (M); On the side of the traveling vehicle body (21) facing the rail (13), a work passage entry position detection sensor (33, 37L, 37R, 40L, 40R) for detecting the rail (13) is provided, and when the work passage entry position detection sensor (33, 37L, 37R, 40L, 40R) detects the work passage entry position while traveling on the moving passage (4), Running The vehicle body (21) is configured to stop.

[0008] The second invention related to the present invention is the first invention related to the present invention. In the vehicle, a sensor arm 34 protruding forward from the front side of a traveling body 21 is provided with work passage entry position detection sensors 33, 37L, 37R, 40L, 40R.

[0009] The third invention related to the present invention is the second invention related to the present invention. In the above, the work passage entry position detection sensors (40L, 40R) are proximity sensors.

[0010] The fourth invention related to the present invention is the second or third invention related to the present invention. In the embodiment, the rail 13 is a hot water pipe and has a rail end 13t that is connected in a U-shape at the start end of the working passage 9, and the sensor arm 34 is provided with contact prevention detection sensors 39, 41 that detect the rail end 13t.

[0011] The fifth invention related to the present invention is any one of the second to fourth inventions related to the present invention. The sensor arm 34 is provided with extension / contraction means 42, 43 for changing the sensor arm 34 into a forward protruding state and a retracted state relative to the traveling vehicle body 21, and is configured so that the sensor arm 34 is extended to the protruding state while traveling on the transfer passage 4 and is shortened to the retracted state while traveling on the working passage 9. Effect of the Invention

[0012] According to the present invention, when moving to adjacent cultivation beds 5, the change in the posture of the traveling body 21 entering between the cultivation beds is reduced, making it easier to align the body. In addition, since the traveling body 21 does not rotate, the space of the moving passage 4 can be made compact. Furthermore, the work passage entry position detection sensors 33, 37L, 37R, 40L, and 40R can reliably detect the rails 13. Also, the distance between the traveling body 21 and the cultivation bed 5 can be set to a predetermined value, and the traveling body 21 can be prevented from contacting the cultivation bed 5. Furthermore, while the traveling body 21 is unlikely to contact the cultivation bed 5 when traveling on the moving passage 4, the traveling body 21 can enter the innermost part of the passage when moving on the work passage 9, so that work can be performed on the crops at the innermost part of the passage. The first invention related to the present invention According to the invention, when the traveling body 21 moves to an adjacent cultivation bed 5, the change in the posture of the traveling body 21 when moving between the cultivation beds is reduced, and the positioning is facilitated. In addition, since the traveling body 21 does not rotate, the space of the moving passage 4 can be made compact.

[0013] According to the second and third inventions related to the present invention, the first invention related to the present invention In addition to the above effects, the working passage entry position detection sensors 33, 37L, 37R, 40L, 40R can reliably detect the rails 13. Also, the distance between the traveling body 21 and the cultivation bed 5 can be kept at a predetermined distance, and the traveling body 21 can be prevented from contacting the cultivation bed 5.

[0014] According to the fourth aspect of the present invention, the second and third aspects of the present invention In addition to the above effects, it is possible to detect that the traveling vehicle body 21 is entering the working passage 9. Also, it is possible to prevent the traveling vehicle body 21 from abnormally approaching the rail 13 while traveling on the transfer passage 4.

[0015] According to the fifth aspect of the present invention, the second to fourth aspects of the present invention In addition to the above effect, the traveling vehicle body 21 is unlikely to come into contact with the cultivation beds 5 when traveling on the moving passage 4. When traveling on the work passage 9, the traveling vehicle body 21 can enter the inner side of the passage, so that work can be performed on the crops at the inner side of the passage. [Brief description of the drawings]

[0016] [Figure 1] 1 is a schematic diagram of a plant cultivation facility that utilizes a work vehicle according to an embodiment of the present invention. [Diagram 2] FIG. 2A is a side view of a harvesting work vehicle of the work vehicle, and FIG. 2B is a plan view of the harvesting work vehicle. [Diagram 3] FIG. 2 is a side view showing an example of harvesting operation of the work vehicle. [Figure 4] FIG. 4 is an explanatory diagram showing the stacking of buckets of the work vehicle. [Diagram 5] FIG. 2 is a side view showing the travel means of the work vehicle and its surroundings. [Figure 6]13A and 13B are plan views showing the detection state of the work passage entry position in the work vehicle. [Figure 7] 6A and 6B are side views showing the movement of a sensor arm in the work vehicle. [Figure 8] 13 is a plan view showing another example of a detection state of the work passage entry position in the work vehicle. FIG. [Figure 9] 13A is a side view showing the travel means and its surroundings of the work vehicle of the other embodiment, and FIG. 13B is a plan view showing the state in which the work passage entry position of the other embodiment is detected. [Figure 10] 13A is a side view showing the travel means and its surroundings of the work vehicle of the other embodiment, and FIG. 13B is a plan view showing the state in which the work passage entry position of the other embodiment is detected. [Figure 11] 13A and 13B are plan views showing the state in which the working passage entry position is detected in the same alternative embodiment. [Figure 12] 5A and 5B are plan views showing an operating state of the extension / contraction means of the sensor arm of the work vehicle according to the embodiment of the present invention. [Figure 13] 13A and 13B are plan views showing other states of operation of the extension / contraction means of the sensor arm. [Figure 14] 1 is a control block diagram of a work vehicle according to an embodiment of the present invention. [Figure 15] 5A and 5B are plan views illustrating the operation of the wheels by the wheel turning means of the work vehicle. [Figure 16] 13 is a plan view illustrating the operation of the wheel by the wheel turning means. FIG. [Figure 17] 13 is a plan view illustrating the operation of the wheel by the wheel turning means. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] A greenhouse system according to an embodiment of the present invention will be described below.

[0018] FIG. 1 shows an example of a cultivation facility, which includes a cultivation room 1, which is a greenhouse in which the indoor environment, such as temperature and humidity, is controlled by heaters and humidifiers, and a shipping room 2 adjacent to the cultivation room 1. In the center of the cultivation room 1, a main passage 4 is provided through which workers, mobile work vehicles (work trolleys) 3, pest control vehicles, etc. can pass, and this main passage 4 is a concrete passage with a concrete road surface. At both sides of the main passage 4, a cultivation space 6 for cultivating crops is formed by arranging a large number of cultivation beds 5, which serve as cultivation units, in rows. The cultivation beds 5 are cultivation beds made of rock wool, which serves as a culture medium, and nutrient solution is supplied to each cultivation bed 5 from a nutrient solution supplying device 7 in the shipping room 2.

[0019] In addition, entrances 8 to the cultivation room 1 equipped with opening and closing doors are provided at both ends of the main passage 4, and one of the entrances 8 can be used to access the adjacent shipping room 2. The other entrance 8 can be used to access the cultivation facility from the outside. The mobile work vehicle 3 can be moved from the main passage 4 to a sub-passage 9 between each cultivation bed 5, and various tasks can be performed on the plants being cultivated while moving the mobile work vehicle 3 along the cultivation beds 5 on the sub-passage 9. The sub-passage 9 is a passage formed in the front-rear direction between the left and right sides of each cultivation bed 5. The mobile work vehicle 3 runs on rails 13 on the left and right heating pipes laid on the sub-passage 9 for heating the entire greenhouse.

[0020] The shipping room 2 is provided with the nutrient solution supplying device 7 and a sorting device 10 that sorts the harvested crops (fruits) such as tomatoes by weight, size, or grade. The sorting device 10 is a pre-treatment device that processes the cultivated crops before shipping. The sorting device 10 is configured with a sorting conveyor 11 that transports and sorts the harvested crops, and harvested product storage sections 12 for each class provided on both sides of the sorting conveyor 11, and is configured to supply the harvested crops from the sorting conveyor 11 to each harvested product storage section 12 and sort them into each class. The sorting conveyor 11 is configured to be bent in an L-shape in a plan view. Each harvested product storage section 12 is provided with a storage box for storing the harvested crops, and the harvested crops are shipped by this storage box.

[0021] An attracting wire 15 is provided on the upper side of the cultivation bed 5 along the cultivation line, and the cultivated plant P is attracted by an attracting string 17 as an attracting member that hangs down from the attracting wire 15 via an attracting hook 16. The attracting hook 16 is configured to be hung from the attracting wire 15, and is configured to appropriately let the wrapped attracting string 17 hang down, as is well known. After the plant grows to a predetermined height (near the attracting hook 16), the attracting string 17 is sequentially shifted in the arrangement direction of the multiple cultivated plants, i.e., in the longitudinal direction of the cultivation bed 5, while letting out the attracting string 17 from the attracting hook 16, to lower the height of the plant, and the plant is continuously cultivated. Therefore, for example, when a tomato f is cultivated, the tomato stem c will extend from the cultivation bed 5 along the attracting string 17 (FIG. 3).

[0022] The mobile work vehicle 3 is a harvesting work vehicle as shown in Figures 2 and 3. A harvesting arm 22 is provided on a traveling body 21 supported for travel by front, rear, left and right traveling wheels 20 so that the traveling body 21 can travel, and a clamping lift mechanism 25, 26 is provided for stacking and unstacking harvest storage buckets A, A... in multiple stages in upper and lower storage spaces 23, 24 formed in the traveling body 21. The harvesting arm 22 and the upper and lower clamping lift mechanisms 25, 26 are operated by actuators such as control motors in response to command signals output by a control device C (see Figure 14) which receives setting signals and input signals from various sensors such as an imaging device (not shown), so that fruit harvesting and fruit storage in the bucket A are automatically performed.

[0023] The buckets A are stacked in the lower storage space 24 of the upper and lower storage spaces 23, 24, and in this state, tomatoes f harvested by the harvesting arm 22 are successively supplied to the topmost bucket A (FIG. 4(a)). When the topmost bucket A is full, the lower clamping lift mechanism 26 lifts the bottommost bucket A, that is, all buckets A, A... rise (FIG. 4(b)). Then, when the topmost bucket A rises to the standby position of the upper clamping lift mechanism 25, the upper clamping lift mechanism 25 engages and lifts the topmost bucket A, so that the topmost bucket A, which contains the tomatoes, waits in the upper storage space 23 (FIG. 4(c)).

[0024] Next, the empty bucket A is fed with the tomatoes f harvested by the harvesting arm 22 until the bucket A at the top of the lower storage space 24 is filled with them. After that, the bucket A supported by the upper clamping lift mechanism 25 is lowered and placed on the full bucket A (Fig. 1(d)), and all the buckets A, A... are raised by the lower clamping lift mechanism 26, and the second top full bucket A is raised while being supported by the upper clamping lift mechanism 25 (Fig. 1(e)). In this way, the buckets A that are successively filled are transferred in a stack to the upper storage space 23. Then, when the bottom bucket A supported by the lower clamping lift mechanism 26 is filled with the harvested tomatoes f (Fig. 1(f)), the harvesting is completed. The bucket A supported by the upper clamping lift mechanism 25 is stacked on this bottom bucket A (Fig. 1(g)), and all the upper buckets A are lowered (Fig. 1(h)). The multi-stage bucket A containing the harvested tomatoes f is then moved to the lower storage space 24. The bucket A waiting in the lower storage space 24 is moved to the outside of the traveling body 21 by appropriately opening the bottom or by conveyor transport means.

[0025] 3, the support base 27 of the harvesting arm 22 is configured to be movable in the front-rear direction of the traveling body 21 by a guide rail 28 provided along the boundary line between the upper and lower storage spaces 23, 24. Therefore, if all the buckets A, A... are positioned in the lower storage space 24, the harvesting arm 22 can be moved forward along the guide rail 28, and the tomatoes f growing on the stems c approaching the building wall 29 can be harvested. Since there are not many harvested tomatoes f, they can be stored in the uppermost bucket A, which already has storage space remaining.

[0026] Next, the traveling mechanism of the mobile work vehicle 3 and its peripheral configuration will be described. The pair of traveling wheels 20 on the front, rear, left and right sides are composed of large-diameter rubber wheels 20a supported by wheel axles 30 and small-diameter raceways 20b supported coaxially, and each wheel axle 30 is configured to be driven by a traveling drive motor 31. Therefore, the rubber wheels 20a run on the main passage 4 (hereinafter referred to as the moving passage 4) in the cultivation room 1, and the raceways 20b run along the rails 13 of the sub-passage 9 (hereinafter referred to as the work passage 9). Each wheel axle 30 is equipped with a wheel turning means M, and the wheel axle 30 is configured to be rotatable around the vertical axis, and the rubber wheels 20a and the raceways 20b are configured to be able to change the angle between 0 degrees and 90 degrees together while the traveling body 21 is fixed. For example, when the rubber wheels 20a run on the moving path 4 in the angle 0 degree direction, and when the angle is changed to the angle 90 degrees, the raceways 20b run along the rails 13 and the work passage 9. Therefore, there is no need to change the direction of the traveling body 21. A specific example of the wheel turning means M provided on each traveling device 20 on the front, rear, left and right sides is a motor shaft provided on the vertical axis, with a wheel axle 30 connected to the lower end and a turning drive motor capable of forward and reverse rotation provided on the upper end. As the turning drive motor rotates forward and backward, the wheel axle 30 rotates around the vertical axis, and at the same time, the rubber wheels 20a and raceways 20b rotate.

[0027] Next, the control of determining the entry position of the work passage 9 in the mobile work vehicle 3 while traveling along the travel passage 4 will be described. The rails 13 are arranged in two rows in parallel, and the ends 13t formed in a roughly U-shape to circulate hot water on the rails 13 are arranged in multiple rows, and the control device C inputs the detection value of the work passage entry position detection sensor 33 and determines whether or not the entry position has been reached based on the detection of this work passage entry position detection sensor 33. The rail ends 13t are provided at the start side of each work passage 9.

[0028] A sensor arm 34 is provided protruding forward of the traveling body 1, and a work passage entry position detection sensor 33 in the form of a limit switch is provided on a sensor support rod 35 connecting the left and right sensor arms 34L, 34R on the forward travel direction Fa side of the transfer passage 4, with a detection actuator 33a of the sensor 33 provided in a hanging state. Depending on the set length of the sensor arm 34, the detection actuator 33a of the work passage entry position detection sensor 33 comes into contact with and detects the rearward travel rail 13L of the two rails 13 of the traveling body 21 (Fig. 6(A)), and further comes into contact with and detects the forward travel rail 13R as the traveling body 21 advances (Fig. 6(B)).

[0029] At this point, the control device C determines that the traveling body 21 has reached the adjacent work passage 9, and controls the traveling drive motor 31 to stop. At the same time, it controls the wheel turning means M to change its angle. When the traveling drive motor 31 is started again, the traveling body 21 moves along the pair of rails 13L, 13R with the track wheels 20b moving in the forward direction Fb along the back side of the work passage 9. Then, an approach position detection sensor (not shown) detects that the traveling body 21 has approached the building wall 29, and the traveling body 21 is controlled to stop, the traveling drive motor 31 is reversed, and the traveling body 21 moves in the backward direction and returns to the transfer passage 4 again.

[0030] Furthermore, the vehicle moves to the adjacent work passage 9 to continue work, but the control means C returns the wheel turning means M to an angle of 0 degrees and drives the travel drive motor 31 again to move the work vehicle body 21 along the transfer passage 4, and repeats the above movement by detecting the entry position of the next work passage 9.

[0031] The example shown in FIG. 7 relates to an improvement of the support structure of the sensor arm 34. The sensor arm 34 is supported on the traveling body 21 so as to be freely retracted forward and backward in the protruding direction, and the tip of the sensor arm 34 engages with the rail end 13t formed in a substantially U-shape to circulate hot water through the rail 13, so that the sensor arm 34 can protrude forward and retract forward of the traveling body 21. That is, when the working body 21 is moving through the working passage 9, the sensor arm 34 does not need to protrude, so it is retracted. Then, a hanging locking member 36 is installed on the sensor support rod 35 so that it can engage with the rail end 13t when the working body 21 leaves the working passage 9, so that the locking member 36 engages with the rail end 13t as the traveling body 21 moves backward, and the sensor arm 34 protrudes further as the traveling body 21 moves backward. The locking member 36 is configured to be able to exceed the rail end 13t, for example, by being made of a material that bends appropriately when the sensor arm 34 is in the maximum protruding state and an external force caused by excessive backward movement is applied.

[0032] 8, work passage entry position detection sensors 37L, 37R in the form of limit switches are provided on the sensor support rod 35 at the tip of the sensor arm 34 at two locations, one on the forward direction Fa side of the travel passage 4 and the other in the rear direction. With this configuration, in addition to the fact that the leading work passage entry position detection sensor 37R has the function of the work passage entry position detection sensor 33 of the above embodiment and can detect the entry position of the work passage 9 as the travelling body 21 moves in the travelling passage 4, the trailing work passage entry position detection sensor 37L detects normally because there is no rail detection and contributes to the judgment of the control device C, but the trailing work passage entry position detection sensor 37L detects and can detect overshooting of the travelling body 21. That is, by setting the distance between the left and right work aisle entry position detection sensors 37L, 37R large relative to the distance between the pair of rails 13, it is possible to determine that the work aisle entry position detection sensor 37L has overshot when it detects the rail 13L. In this case, the travel drive motor 31 is rotated in the reverse direction to move the traveling vehicle body 21 backward until it detects the rail 13L again, thereby making it possible to reach the correct entry position.

[0033] In the example shown in Fig. 9, a contact prevention detection sensor 39 is disposed on an auxiliary support rod 38 that spans the middle part of a sensor arm 34. When this contact prevention detection sensor 39 comes into contact with the rail 13 or the rail end 13t and detects this, it is possible to determine that there is a high possibility that the traveling vehicle body 21 moving along the moving passage 4 is abnormally approaching the cultivation bed 5, and to control the traveling vehicle body 21 to move away from the cultivation bed 5 until the contact prevention detection sensor 39 is no longer detecting the contact.

[0034] In the example shown in Fig. 10, the working passage entry position detection sensors 33, 37L, 37R and the contact prevention detection sensor 39 are replaced with proximity sensor type working passage entry position detection sensors 40L, 40R and contact prevention detection sensor 41. Proximity sensors are sensors that can detect the presence or absence of an object without contacting it, and include induction type sensors, capacitance type sensors, magnetic sensors, etc. In the case of contact sensors such as limit switch types, there is a possibility that the device or actuator may be displaced by the impact of the impact, but if they are configured with proximity sensors, this risk is less likely and they can be configured relatively inexpensively.

[0035] In the example shown in FIG. 11, at least one of the proximity sensor type work passage entry position detection sensors 40L, 40R (both in the illustrated example) is configured with a pair of front and rear proximity sensors 40Lf, 40Lr and 40Rf, 40Rr. When the traveling vehicle body 21 enters the work passage 9 in a plan view, if the traveling vehicle body 21 does not enter at an angle to the rail 13, and the work passage entry position detection sensors 40Lf, 40Lr detect the rail 13 almost simultaneously, it is determined that the traveling vehicle body 21 is entering in a normal direction. The same applies to the relationship between the work passage entry position detection sensors 40Rf, 40Rr. On the other hand, if one of the work passage entry position detection sensors 40Lf, 40Lr detects the work passage entry position before the other, it is determined that the traveling vehicle body 21 is entering in an oblique direction in a plan view. For this oblique entry, it is recommended to temporarily move the traveling vehicle body 21 back as specified, adjust the entry posture, and then enter again.

[0036] In the example shown in Fig. 12, a cylinder mechanism 42 is provided as telescopic means for setting the sensor arm 34 in an extended state protruding in front of the traveling body 21 or in a contracted state retracted, and by arbitrarily or automatically retracting it, it is possible to prevent collision with other objects by retracting it during movement in the working passage 9. Note that in Fig. 13, a pantograph 43 is configured as the telescopic means, and a similar effect can be obtained.

[0037] In the above embodiment, the work passage entry position detection sensors 33, 37L, 37R are positioned slightly offset from the rail 13 detection position at the normal entry position, and the entry position is determined to be appropriate by judging whether the detection state switches to a non-detection state. However, the sensor positions can also be arranged so that the appropriate state is when the work passage entry position detection sensors 33, 37L, 37R are actually detecting the rail 13.

[0038] 15 to 17 show the operation of the wheel turning means M. FIG. 15(A) and FIG. 15(B) show the case where the traveling device 20 of the working vehicle body 21, which has retreated from the working passage 9 to the moving passage 4, is changed to the moving passage 4 traveling state, and the arrows indicate the turning direction. In the case of FIG. 15(A), the front, rear, left and right wheel axles 30, the rubber wheels 20a and the track rings 20b are turned in the same direction. Even in this case, the direction of the rubber wheels 20a can be changed to a state along the moving passage 4, but the phase of the front wheel side rubber wheels and track rings 20b supported by the front wheel axle 30 of the traveling vehicle body 21 is different, and there is a risk that a turning force in the vehicle body turning direction will be generated when the traveling device 20 is driven. For this reason, as shown in FIG. 15(B), by making the turning directions of the left and right wheel axles 30 different, the turning forces are cancelled out and the above-mentioned risk is reduced.

[0039] Figure 16 shows the case where the track wheels 20b run on the rails 13 of the work passage 9. By turning the wheel turning means M, the track wheels 20b are turned so that they are on the inside of the rubber wheels 20a on both the left and right sides, giving the large-diameter rubber wheels 20a a function to prevent them from coming off the rails 13.

[0040] 17, the wheel axle 30 is set in an oblique direction with a turning angle of about 45 degrees by the wheel turning means M. This makes it possible to obtain a turning operation. [Explanation of symbols]

[0041] 4. Passageway 5. Cultivation Beds 9 Work passage 13 Rail 13t Rail end 20 Running wheels 20a Rubber Wheel (Wheel) 20b Raceway ring 21 Running vehicle 33 Work passage entrance position detection sensor 34 Sensor arm 37L Work passage entrance position detection sensor 37R Work passage entrance position detection sensor 39 Contact prevention detection sensor 40L Work passage entrance position detection sensor 40R Work passage entrance position detection sensor 41 Contact prevention detection sensor 42 Cylinder mechanism (expansion means) 43 Pantograph (extension means) M Wheel turning means

Claims

1. In a work vehicle that travels on each of the work passages (9) between a large number of cultivation beds (5) and on a transfer passage (4) that leads to each of the work passages (9) at the end of the cultivation beds (5), a travelling body (21) is provided with raceways (20b) that travel on a pair of left and right rails (13) arranged on each of the work passages (9) and wheels (20a) that travel on the transfer passage (4), the wheels (20a, 20b) are rotatable by a wheel turning means (M), work passage entry position detection sensors (33, 37L, 37R, 40L, 40R) that detect the rails (13) are provided on the side of the travelling body (21) facing the rails (13), and when the work passage entry position detection sensors (33, 37L, 37R, 40L, 40R) detect the work passage entry position while traveling on the transfer passage (4), the travelling body (21) stops, A sensor arm (34) protruding forward from the front side of the traveling vehicle body (21) is provided with a work passage entry position detection sensor (33, 37L, 37R, 40L, 40R), The work vehicle is provided with an extension / contraction means (42, 43) for changing the sensor arm (34) from a forward projecting state to a retracted state relative to the traveling body (21), and the sensor arm (34) is extended to the projecting state while traveling on the moving passage (4) and shortened to the retracted state while traveling on the working passage (9).

2. 2. A work vehicle according to claim 1, wherein the work passage entry position detection sensors (40L, 40R) are proximity sensors.

3. 3. A work vehicle as described in claim 1 or claim 2, wherein the rail (13) is a hot water pipe and has a rail end (13t) that is connected in a U-shape at the start of the work passage (9), and the sensor arm (34) is provided with a contact prevention detection sensor (39, 41) that detects the rail end (13t).

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