Track travel-type work vehicle

Abstract

To provide a track travel-type work vehicle provided with a travel device which enables both track traveling and ground traveling even with a simple structure.SOLUTION: A travel device installed on a chassis 2 of this work vehicle is provided with track wheels 21a and 21b of a motor drive type used for track driving and ground wheels 31a-31c used for ground traveling. An elevation difference H between a lowest point P2 of a part of a tread 211 provided on each of the track wheels 21a and 21b in contact with the upper surface of a track 80 and a lowest point P1 of each of the ground wheels 31a-31c is set equal to or smaller than an outer diameter D of a circulation pipe 81 constituting the track 80, and the lowest point P1 of the ground wheels of each of the ground wheels 31a-31c is set at a position lower by an elevation difference δ than a lowest pint P3 of a flange 212 of each of the track wheels 21a and 21b. Thus, only by moving the work vehicle from on the track 80 onto the ground G, the ground wheels 31a-31c can be grounded to travel on the ground with the track wheels 21a and 21b floating from the ground G.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The present invention relates to a track-running work vehicle, and more specifically to a track-running work vehicle that is capable of running on the ground and has a distinctive running gear configuration, such as a work vehicle that uses a circulation pipe for circulating a heat transfer medium such as hot water and is placed in a horticultural greenhouse, or that runs on a track formed by dedicated rails or the tracks of a road-rail vehicle (in this specification, both uses are collectively referred to as a "track-running work vehicle"). [Background technology]

[0002] As an example, one such horticultural greenhouse has a circulation pipe placed on the ground inside the greenhouse, and a heat transfer medium such as hot water is circulated through this circulation pipe to heat the inside of the greenhouse.

[0003] In such a horticultural greenhouse, as shown in the plan view of Figure 11 as an example, planting areas 91 where crops etc. are planted within the greenhouse 90 are alternately provided, and aisles 92 for managing the crops grown in the planting areas 91 and carrying out tasks such as harvesting are arranged, and by arranging hot water circulation pipes 81 in each aisle, not only is it possible to heat the entire greenhouse 90, but for example, by arranging two circulation pipes 81, 81 in parallel in each aisle 92, the circulation pipes 81, 81 can be repurposed as tracks 80 for running track-type work vehicles, allowing the work vehicles to run within the greenhouse 90, thereby improving workability during crop management and harvesting, and aerial work vehicles with a deck that can be raised and lowered for workers to board are also used as such work vehicles.

[0004] As an example of a track-running work vehicle that runs on a track 80 formed by circulation pipes 81, 81 in this manner, as shown in Figure 12, there is proposed a work trolley (hereinafter referred to as the "work vehicle") 100 that is capable of running on a track 80 by providing a metal disk 45 that rotates while making contact with the side of the circulation pipe 81 that constitutes the track 80 inside the wheel 40 that rolls on the ground G (see Patent Document 1), and a work vehicle 100 that can run on both the track and on the ground using a common wheel 50 with a fixed rotation direction, as shown in Figure 13 (see Patent Document 2).

[0005] Here, the track 80 formed by the circulation pipe 81 is provided in each of the passages 92 provided between the planting sections 91 as shown in Figure 11, so when work is completed in one of the passages 92 (92a as an example) using the work vehicle 100 and work is to be moved to another passage 92 (92b as an example), the work vehicle 100 must be moved from one track 80a provided in one passage 92a to another track 80b provided in the other passage 92b.

[0006] When moving the work vehicle 100 from one track 80a to another track 80b in this way, the work vehicle 100 that has been traveling along the first track 80a is first moved beyond the end of the first track 80a (part 82 in Figure 11) onto the ground G, and then this work vehicle 100 is moved on the ground G to a position on the extension of the other track 80b, and then, in the work vehicle described with reference to Figure 12, this is done by moving the work vehicle 100 forward (or backward) towards the other track 80b until the other track 80b is positioned between the discs 45, 45 provided inside the wheels 40, 40, and in the work vehicle 100 of Figure 13, this is done by moving the work vehicle 100 forward (or backward) towards the other track 80b until the wheels 50 ride up onto the other track 80b.

[0007] In this way, in order to be able to move the work vehicle 100 from one track 80a to another track 80b, it is necessary to have it travel on ground G where no track 80 is provided, while changing direction. The work vehicle 100 in Figure 12 is configured to be able to travel on its own on ground G from one track 80a to another track 80b by using the front wheels 40a, 40a as steering wheels and by being provided with a steering mechanism 46 that steers the front wheels 40a, 40a.

[0008] In addition, in the work vehicle 100 of Figure 13, both wheels 50 (50a, 50b) are fixed wheels that cannot be steered, and a rise-and-fall caster 51 having a rotation axis that rotates in a direction perpendicular to the rotation axis of the wheel 50 is provided on the front side of the chassis 102, and by lowering the caster 51, the front wheel 50a is raised off the ground, and the front end of the work vehicle 100 can be moved left and right by pushing it with a hand, so that the work vehicle 100 can be rotated around the rear wheels 50b, 50b to change direction. [Prior art documents] [Patent documents]

[0009] [Patent Document 1] Japanese Patent Application Publication No. 2017-171216 [Patent Document 2] Japanese Patent Application Laid-Open No. 2006-206260 Summary of the Invention [Problem to be solved by the invention]

[0010] Of the work vehicles 100 described above, in the work vehicle 100 described in Patent Document 1, which was explained with reference to Figure 12, the front wheels 40a are configured as steering wheels, and a steering mechanism 46 is provided to steer these steering wheels 40a, so that a worker on board the work vehicle 100 can drive the work vehicle 100 on the ground G while operating the handle 47 provided on the steering mechanism 46, thereby making it possible to self-propel the work vehicle 100 from one track 80a to another track 80b.

[0011] However, the track-running work vehicle 100 does not require a steering mechanism 46 because it is normally used by running along the track 80, and adopting a configuration that includes a steering mechanism 46 would result in increased costs due to the increased number of parts.

[0012] Furthermore, since the front wheels 40a are steerable and not fixed, if the passengers do not fix the front wheels by gripping the handlebars, not only will the front wheels rattle even when running on the track, reducing running stability, but if a steering angle is unintentionally applied to the front wheels 40a, there is also a risk that the front wheels 40a will run onto the track 80 or derail from the track 80.

[0013] On the other hand, in the work vehicle 100 described in Patent Document 2, which is explained with reference to Figure 13, both the front wheels 50a and the rear wheels 50b are configured as fixed wheels that cannot be steered, and by using wheels with flanges, the risk of derailment is low and the vehicle can run stably on the track 80, and costs can be reduced because no steering mechanism is provided.

[0014] However, the wheels 50 (50a, 50b) of the work vehicle 100 shown in Figure 13 are shared for both track running and ground running, so when running on the ground, the vehicle can only run straight forward and backward.

[0015] Therefore, the work vehicle 100 shown in Figure 13 has casters 51, 51 on the front side of the chassis 102, and a lifting mechanism for raising and lowering these casters 51, 51.As a result, the device configuration becomes complex and the cost increases due to the increased number of parts.

[0016] Furthermore, in the configuration of the work vehicle 100 described in Patent Document 2 shown in Figure 13, when the casters 51, 51 are lowered, the work vehicle cannot travel forward or backward, and when the casters 51, 51 are raised, the work vehicle cannot change direction and can only travel straight forward or backward.

[0017] As a result, when trying to drive the work vehicle 100 described in Patent Document 2 on the ground, each time a direction change is made, the casters 51, 51 must be lowered until the front wheels 50a are lifted off the ground, then the front side of the work vehicle 100 must be rotated around the rear wheels 50b to change direction, and then the casters 51, 51 must be raised and stored again, the front wheels 50a must be placed on the ground, and the work vehicle 100 must then be moved straight forward or backward, and these operations must be repeated to move from one track 80a to another track 80b, which is cumbersome.

[0018] Thus, in the work vehicle 100 described in Patent Document 2, the lifting mechanism frequently repeats the raising and lowering operation of the casters 51, 51, which increases the risk of failure of the lifting mechanism or the casters 51, 51.

[0019] Furthermore, in the work vehicle 100 described in Patent Document 2, if the casters 51 or the caster lifting mechanism break down, not only will it become difficult to move on the ground while changing direction, but if the casters 51, 51 break down in a lowered position and can no longer be raised (stored), the work vehicle 100 will not even be able to move straight forward or backward.

[0020] Therefore, there is a need to develop a track-type work vehicle equipped with a running device that allows for easier and more reliable running on the ground with direction changes while reducing the risk of breakdowns by using a simpler device configuration.

[0021] Therefore, the present invention was developed to eliminate the drawbacks of the above-mentioned conventional technology, and aims to provide a track-running work vehicle equipped with a running device that can run not only on a track but also on the ground with direction changes, with a relatively simple configuration, without adopting complex structures such as a lifting mechanism. [Means for solving the problem]

[0022] The means for solving the problems are described below together with the reference numerals used in the description of the embodiment of the invention. These reference numerals are intended to clarify the correspondence between the claims and the description of the embodiment of the invention, and needless to say, are not used to restrict the interpretation of the technical scope of the present invention.

[0023] In order to achieve the above object, the track-traveling type work vehicle 1 of the present invention is A running device 10 is provided on the chassis 2, and a pair of tracks 80 are made up of hot water circulation pipes 81 arranged parallel to the ground G. In this running vehicle 1, The traveling device 10 includes a track traveling device 20 for traveling on the track 80, and a ground traveling device 30 for traveling on the ground G, The track running device 20 is provided with a pair of track wheels 21a, 21a; 21b, 21b, each of which has a tread 211 placed on the track 80 and a flange (212, 212') protruding from the end of the width direction of the tread 211 in the outer circumferential direction, at one end 2a side and the other end 2b side of the chassis 2 in the track running direction, and a drive motor 22 that drives at least one of the track wheels 21a, 21a; 21b, 21b, The ground running device 30 is provided with a pair of rotatable ground wheels 31a, 31a; 31b, 31b (or 31b', 31b') at least at the one end 2a side and the other end 2b side of the chassis 2, respectively, which enable the ground running, and which are positioned so as not to interfere with the track 80 when running on the track, The pair of ground wheels provided on at least one side of the one end 2a or the other end 2b of the chassis 2 are configured as swivel casters, The height difference H (see Figure 5) between the lowest point P2 of the part of the tread surface 211 of the track wheels 21a, 21b that comes into contact with the upper surface of the track and the lowest point P1 of the ground wheels 31a, 31b is set to be equal to or less than the outer diameter D of the pipe 81 that constitutes the track 80, and the lowest point P1 of the ground wheels 31a, 31b is set at a position lower than the lowest point P3 of the flange 212 of the track wheels 21a, 21b (in the embodiment, a position lower by the height difference δ in Figure 5) (Claim 1).

[0024] The pair of ground wheels 31a, 31a and 31b, 31b on the one end 2a side and the other end 2b side of the chassis 2 can both be swivel casters (claim 2).

[0025] The above-mentioned swivel caster can be one that fixes the yoke 311 of the swivel caster (see the enlarged view in Figure 5 for the yoke 311) so that it cannot rotate at any rotation position, and is equipped with a stopper mechanism (not shown) that can release this fixation (Claim 3).

[0026] In a configuration in which both of the pair of ground wheels 31a, 31a; 31b, 31b provided on the one end 2a side and the other end 2b side of the chassis 2 of the ground running device 30 are swivel casters, a rotation direction is fixed in the same direction as the track wheels 21a, 21b at an intermediate position between the pair of ground wheels 31a, 31a provided on the one end 2a side of the chassis 2 and the pair of ground wheels 31b, 31b provided on the other end 2b side of the chassis 2. It is also possible to provide a pair of fixed wheels 31c, 31c for running on the ground, each of which is rotatable, and in this case, the fixed wheels 31c, 31c are provided in a position where they do not interfere with the track 80 when running on the track, and so that the lowest point P4 of the fixed wheels 31c, 31c is at the same height as the lowest point P1 of the pair of ground wheels 31a, 31a; 31b, 31b provided on the one end 2a side and the other end 2b side of the chassis 2 (Claim 4).

[0027] A deck 4 on which workers can board and a lifting mechanism 3 for raising and lowering the deck 4 may be provided on the chassis 2 equipped with the running device 10 of the above structure (claim 5). [Effects of the Invention]

[0028] With the configuration of the present invention as described above, the track-traveling type working vehicle 1 of the present invention can achieve the following significant effects.

[0029] The height difference H between the lowest point P2 of the part of the tread surface 211 of the track wheels 21a, 21b that comes into contact with the upper surface of the track 80 and the lowest point P1 of the ground wheels 31a, 31b, 31b', 31c is set to be equal to or less than the outer diameter D of the pipe 81 that constitutes the track 80 (H≦D), and the lowest point P1 of the ground wheels 31a, 31b, 31b', 31c is set at a position lower than the lowest point P3 of the flange 212 of the track wheels 21a, 21b (a position lower by the height difference δ in the example of Figure 5).As a result, simply by lowering the work vehicle 1 from the track 80 onto the ground G, the ground wheels 31a, 31b, 31b', 31c come into contact with the ground, while the track wheels 21a, 21b, including the flange 212, are positioned in a raised state where they do not come into contact with the ground.

[0030] As a result, without providing a lifting mechanism for raising and lowering the ground wheels 31a, 31b, 31b', 31c on the ground running device 30, it is possible to switch the running state from track running using the track running device 20 to ground running using the ground running device 30 simply by running the work vehicle 1 over the end of the track 80 onto the ground G, which makes it possible to reduce costs compared to when a lifting mechanism is provided, and by making it possible to significantly simplify the device configuration, it is less prone to malfunctions, and it is possible to equip the work vehicle 1 with a ground running device 30 that is highly reliable and easy to maintain.

[0031] Furthermore, at least one of the pair of ground wheels 31a, 31a; 31b, 31b provided on one end 2a and the other end 2b of the chassis 2 is made into a swivel caster, so that the work vehicle 1 can be easily turned and changed direction by pushing it by hand from the side while traveling on the ground.

[0032] In particular, in a configuration in which the pair of ground wheels 31a, 31a; 31b, 31b provided on one end 2a and the other end 2b of the chassis 2 are both swivel casters, the work vehicle 1 can be driven over the end of the track 80 onto the ground G, and then by manually pushing the work vehicle 1 from the side, the work vehicle 1 can be driven on the ground in a direction perpendicular to the longitudinal direction of the track 80 as shown in Figure 9, and the work vehicle 1 can be moved from one track 80 (for example, 80a) to another track 80 (for example, 80b) without turning the work vehicle 1.

[0033] Furthermore, if all or some of the ground wheels (31a, 31a and / or 31b, 31b) are made swivel casters, the straight-line running ability of the work vehicle 1 will be reduced, and in particular, if the ground is inclined, it will be difficult to run in a direction that crosses the direction of the inclination. However, if swivel casters are used that fix the yoke 311 so that it cannot be rotated at any rotation position and that are equipped with a stopper mechanism (not shown) that can release this fixation, the straight-line running stability of the work vehicle 1 can be improved by running the work vehicle 1 with the yoke 311 fixed by the stopper mechanism, and the work vehicle 1 can be easily pushed by hand even on inclined ground.

[0034] Furthermore, in a configuration in which both of the pairs of ground wheels 31a, 31a; 31b, 31b provided on one end 2a and the other end 2b of the chassis 2 are swivel casters, and a pair of fixed wheels 31c, 31c for ground running are provided at an intermediate position between the pair of ground wheels 31a, 31a provided on one end 2a of the chassis 2 and the pair of ground wheels 31b, 31b provided on the other end 2b of the chassis 2, and each of these wheels is rotatable and fixed in the same rotational direction as the track wheels 21a, 21b, straight-line stability can be significantly improved compared to when ground running is performed using only swivel casters 31a, 31b.

[0035] Furthermore, with this configuration, it is possible to rotate the work vehicle 1 around the fixed wheels 31c, 31c, and by rotating the work vehicle 1 with a small turning radius, it is possible to change direction within a small space.

[0036] Furthermore, the work vehicle 1 is configured with a deck 4 on the chassis on which workers can board, and a lifting mechanism 3 for raising and lowering the deck 4, making it easy to manage tall plants and harvest crops from those plants. [Brief explanation of the drawings]

[0037] [Figure 1] 1 is a perspective view of a work vehicle according to a first embodiment (with the deck lowered). [Figure 2] 1 is a perspective view of a work vehicle according to a first embodiment (with the deck raised); [Figure 3] FIG. 2 is a perspective view of the chassis portion of the work vehicle of the first embodiment as viewed from the bottom side. [Figure 4] FIG. 2 is a rear view of the chassis portion of the work vehicle of the first embodiment. [Figure 5] FIG. 2 is a side view of the chassis portion of the work vehicle of the first embodiment. [Figure 6] FIG. 10 is a side view of the chassis portion of the work vehicle of the second embodiment. [Figure 7] FIG. 11 is a side view of the chassis portion of the work vehicle of the third embodiment. [Figure 8] This is an explanatory diagram of the operations when moving a work vehicle (Example 1) from one track to another track, where (A) shows the operation of lowering the work vehicle from one track to the ground, (B) shows the operation of turning the work vehicle, (C) shows the operation of moving the work vehicle to an extension of the other track, (D) shows the operation of turning the work vehicle, and (E) shows the operation of placing the work vehicle on the other track. [Figure 9] FIG. 10 is an explanatory diagram of the operation when the work vehicle of the second embodiment is moved from one track to another track. [Figure 10] 10 is an explanatory diagram of the turning operation of the work vehicle of the third embodiment. FIG. [Figure 11] FIG. 1 is an explanatory diagram of an example of the internal configuration of a house equipped with a circulation pipe. [Figure 12] FIG. 1 is a front view of a conventional work vehicle (corresponding to FIG. 2 of Patent Document 1). [Figure 13] FIG. 1 is a perspective view of a conventional work vehicle (corresponding to FIG. 1 of Patent Document 2). DETAILED DESCRIPTION OF THE INVENTION

[0038] The configuration of the present invention will be described below with reference to the accompanying drawings.

[0039] In the following explanation, the track-traveling work vehicle 1 of the present invention will be explained as an example configured as a high-altitude work vehicle, but the configuration of the running device 10 provided on the chassis of the work vehicle 1 of the present invention can also be used in various work vehicles other than high-altitude work vehicles, such as harvest transport vehicles, and low-altitude work vehicles that transport workers who work standing or sitting on the work vehicle and perform work at low altitudes.

[0040] Furthermore, in the following embodiments, the work vehicle 1 of the present invention will be described as being configured as a high-altitude work vehicle equipped with a lifting mechanism 3 that raises and lowers the deck 4 on which the worker boards, but this is not limited to this configuration. For example, the configuration of the running device 10 of the present invention can be applied to a high-altitude work vehicle that has a work platform with stairs formed by assembling a pipe frame or the like on the chassis 2, and allows the worker to work at height by climbing and descending the stairs on his own and boarding the work platform, and the configuration of the present invention is not limited to the configuration described below.

[0041] [Overall configuration of the work vehicle] In Figures 1 and 2, reference numeral 1 denotes a track-running type work vehicle of the present invention, and this work vehicle 1 is equipped with a chassis 2 equipped with a running device 10, and a deck 4 that rises and falls on the chassis 2 via a lifting mechanism 3 consisting of a scissor link mechanism.

[0042] A protective fence 5 is provided on this deck 4 to prevent workers and luggage on the deck 4 from falling, and when the deck 4 is lowered and the work vehicle 1 is pushed by hand to move on the ground G, the movement can be easily made by grabbing the protective fence 5.

[0043] In the illustrated embodiment, an example of a work vehicle 1 of the present invention is shown as a high-altitude work vehicle having a structure in which the deck 4 can be raised and lowered by a lifting mechanism 3 consisting of a scissor link mechanism, but the structure of the present invention can also be applied to high-altitude work vehicles equipped with various known lifting mechanisms, such as a high-altitude work vehicle in which the deck can be raised and lowered by a telescopic mast that is erected vertically on the chassis 2 and extends and contracts in the vertical direction.

[0044] [Chassis] (1) Overall structure of the chassis The aforementioned chassis 2, which is equipped with a deck 4 and a lifting mechanism 3 for raising and lowering the deck 4, is configured in a rectangular box shape when viewed from above, as shown in Figures 1 to 3, and is equipped with a running device 10 that enables the box-shaped chassis 2 to run.

[0045] As described with reference to Figure 11, this running device 10 is equipped with a track running device 20 for running on a track 80, which is here formed by a pair of circulation pipes 81, 81 and is arranged parallel to the ground of a passage 92 provided in a horticultural greenhouse 90, and a ground running device 30 for running on the ground G (see Figure 3).

[0046] (2) Track running device The track running device 20 described above enables running on a track with the longitudinal direction of the chassis 2 as the running direction, and is equipped with a pair of track wheels 21a, 21a; 21b, 21b arranged at one end 2a and the other end 2b of the longitudinal direction of the chassis 2, respectively, at an interval corresponding to the width of the track 80, and a drive motor 22 that drives at least one of the track wheels 21a, 21a; 21b, 21b (in the illustrated example, all of the track wheels 21a, 21a; 21b, 21b).

[0047] As shown in the enlarged view in Figure 4(A), the above-mentioned track wheels 21a, 21b each have a tread 211 which is the contact surface with the upper part of the track 80 (here, the circulation pipe 81), and a flange 212 which protrudes outward from the widthwise end of the tread 211. In this embodiment, a pair of track wheels 21a, 21a; 21b, 21b which have the flange 212 at one widthwise end of the tread 211 are attached symmetrically to both ends of the axle 23, so that the track 80 is positioned between the flanges 212, 212 and the treads 211 of the track wheels 21a, 21a; 21b, 21b are placed on the track 80.

[0048] The tread surface 211 may be formed in a cylindrical shape as shown in FIG. 4(A), but may also be formed in a tapered shape with the diameter of the tread surface 211 varying in the width direction.

[0049] Furthermore, the track wheels 21a, 21a; 21b, 21b may be attached in a different manner to the axle 23 so that the tread 211 is placed on the track 80 (circulation pipe 81) with the flange 212 positioned inside the track as shown in Figure 4(B), and track wheels 21a, 21b may be used that have flanges 212', 212' provided on both ends of the width of the tread 211, as shown in the enlarged view shown as a "variant example" in Figure 4(A), so that each of the circulation pipes 81, 81 is inserted between a pair of flanges 212', 212' provided on each track wheel 21a, 21b, and in this case, track wheels 21a, 21b may be used that have a structure similar to a door roller, in which the surface of the tread 211 changes into a semicircular arc shape from the tread 211 to the inner side of the flanges 212', 212', and a semicircular arc groove is formed between the flanges 212', 212'.

[0050] However, in a configuration in which the circulation pipe 81 is folded back in a loop at the end of the track 80 as shown in Figure 11, by configuring a pair of track wheels 21a, 21a; 21b, 21b, which have a flange 212 only on one widthwise end side of the tread 211 as shown in Figures 3 and 4(A), to be symmetrically attached to both ends of the axle 23 with the flange 212 facing outward, it is possible to avoid interference between the flange 212 and the part 82 of the circulation pipe 81 that connects the end of the track 80 in the widthwise direction.

[0051] When the track 80 is arranged between the flanges 212, 212 of a pair of track wheels 21a, 21a; 21b, 21b in this manner, the inner spacing W2 of the flanges is made larger than the outer width W1 of the track as shown in Figure 4(A), within the range where the track wheels 21a, 21a; 21b, 21b do not derail.

[0052] This configuration makes it easier to align the work vehicle 1 when it is placed on the track 80.

[0053] At least one of these track wheels 21a, 21a; 21b, 21b is configured to be rotationally driven by a drive motor 22, and in the illustrated embodiment, the rotational driving force of the drive motor 22 is transmitted to axles 23, 23 that connect a pair of track wheels 21a, 21a; 21b, 21b provided on one end 2a and the other end 2b of the chassis 2, respectively, via power transmission means (e.g., a chain and a sprocket, etc.) not shown, thereby rotating all of the track wheels 21a, 21a; 21b, 21b, so that the work vehicle 1 can run on the track 80.

[0054] (3) Ground running device The ground running device 30 is provided so that when the work vehicle 1 of the present invention is lowered from the track 80 onto the ground G where there is no track 80, the worker can push the work vehicle 1 by hand to run on the ground G, and at least at one end 2a and the other end 2b of the longitudinal direction of the chassis 2, a pair of ground wheels 31a, 31a; 31b, 31b (or 31b', 31b') that enable running on the ground are provided in positions that do not interfere with the track 80 when running on the track.

[0055] As shown in Figure 11, in a configuration in which the circulation pipe 81 is folded back in a loop at the end of the track 80, the ground wheels 31a, 31a; 31b, 31b are positioned further outboard in the width direction of the chassis 2 than the track wheels 21a, 21a; 21b, 21b, which is preferable in that it also avoids interference with the part 82 of the circulation pipe 81 that connects the ends of the track 80 in the width direction.

[0056] Of the two pairs of ground wheels 31a, 31a; 31b, 31b mentioned above, the pair of ground wheels 31a, 31a or 31b, 31b provided at at least one of the longitudinal ends 2a and 2b of the chassis 2 are constituted by known swivel casters.

[0057] This swivel caster has a structure in which a wheel 312 is rotatably attached to a yoke 311 that is rotatable around a vertical axis (see enlarged view in Figure 5), and by rotating the yoke 311 horizontally, the rotation direction (travel direction) of the wheel 312 can be directed in any direction over 360°.

[0058] Although not shown in the figures, some such swivel casters are equipped with a stopper mechanism that fixes the rotation position of the aforementioned yoke 311 at any position so that it cannot rotate, and that allows this fixation to be released.In the work vehicle 1 of the present invention, all or some of the swivel casters used as the aforementioned ground wheels 31a, 31a; 31b, 31b may be swivel casters equipped with such a stopper mechanism.

[0059] In the embodiment shown in Figure 5, both the ground wheels 31a and 31b provided on one end 2a and the other end 2b of the chassis 2 are configured as swivel casters, but instead of this configuration, as shown in Figure 7, either one of the end 2a or the other end 2b (the other end 2b in the example of Figure 7) may be configured as a fixed wheel 31b' whose rotation direction is fixed in the same direction as the track wheels 21a and 21b.

[0060] Furthermore, in the embodiment shown in Figure 5, a pair of swivel casters 31a, 31a; 31b, 31b are provided as ground wheels at each of one end 2a and the other end 2b of the chassis 2, and a pair of fixed wheels 31c, 31c, each of which is independently rotatable and whose rotation direction is fixed in the same direction as the track wheels 21a, 21b, are further provided as ground wheels at an intermediate position between the swivel caster 31a at one end 2a and the swivel caster 31b at the other end. However, instead of this configuration, as shown in Figure 6, the ground wheels may be formed only by the swivel casters 31a, 31b provided at each of one end 2a and the other end 2b of the chassis 2, and fixed wheels (wheels corresponding to symbol 31c in Figure 5) as ground wheels may not be provided.

[0061] The ground wheels 31a, 31b, 31b', 31c provided on the ground running device 30 configured as described above are attached to the chassis 2 so that, as shown in Figure 5, the height difference H between the lowest point P2 of the part of the tread surface 211 of the track wheels 21a, 21b that comes into contact with the upper surface of the track 80 and the lowest point P1 of the ground wheels 31a, 31b, 31b', 31c is equal to or less than the outer diameter D of the circulation pipe 81 that constitutes the track (H < D), and the lowest point P1 of the ground wheels 31a, 31b, 31b', 31c is lower than the lowest point P3 of the flange 212 of the track wheels 21a, 21b (a position lower by the height difference δ in Figure 5).

[0062] With this configuration, when the work vehicle 1 is lowered from the track 80 onto the ground G, the ground wheels 31a, 31b, 31b', 31c come into contact with the ground, while the track wheels 21a, 21b, including the flanges 212, are in a raised state without coming into contact with the ground, making it possible for the work vehicle 1 to travel using the ground wheels 31a, 31b, 31b', 31c.

[0063] Furthermore, if the height difference H between the lowest point P2 of the part of the tread surface 211 of the track wheels 21a, 21b that comes into contact with the upper surface of the track 80 and the lowest point P1 of the ground wheels 31a, 31b, 31b', 31c is made too small compared to the outer diameter D of the circulation pipe 81, the work vehicle 1 will be subjected to a large impact when lowering it from the track 80 onto the ground G, and it will be difficult to get the work vehicle 1 up onto the track 80 from the ground G.

[0064] On the other hand, when running on the track, if the tread surfaces 211 of the track wheels 21a, 21b are in contact with the track 80, track running is possible even if the ground wheels 31a, 31b, 31b', 31c are in contact with the ground, so it is desirable that the above-mentioned height difference H and the outer diameter D of the circulation pipe 81 be similar dimensions, and they may also be the same dimension (H=D).

[0065] On the other hand, to prevent the flanges 212 of the track wheels 21a, 21b from coming into contact with the ground when running on the ground, the lowest points P1 of the ground wheels 31a, 31b, 31b', 31c are set at a position lower than the lowest point P3 of the flanges 212, creating a height difference δ (0<δ) between the lowest point P3 of the flanges 212 and the lowest point P1 of the ground wheels 31a, 31b, 31b', 31c.

[0066] It is desirable to set this height difference δ taking into consideration the margin required to prevent the flanges 212 of the track wheels 21a, 21b from coming into contact with the ground when the wheels are running on the ground.

[0067] [Operations, etc.] (1) Example 1 (Figure 5) Of the work vehicles 1 of the present invention described above, the work vehicle 1 (embodiment 1) having the configuration shown in Figures 3 to 5, which is equipped with a pair of swivel casters 31a, 31a; 31b, 31b on each of the one end 2a and the other end 2b of the chassis 2 as ground running devices 30, and with fixed wheels 31c, 31c at an intermediate position between the swivel casters 31a, 31a on the one end 2a side and the swivel casters 31b, 31b on the other end 2b side, can be moved from one track to another by the following steps shown in Figure 8.

[0068] When moving the work vehicle 1 from one track 80a to another track 80b, first, the work vehicle 1 is lowered onto the ground G from the first track 80a.

[0069] This work can be easily performed by using the track running device 20 to run the work vehicle 1 beyond the end of one track 80a onto the ground G (to a position on the extension of one track) (Figures 8(A) to (B)).

[0070] In this way, by moving from one track 80a onto the ground G, the ground wheels 31a to 31c provided on the ground running device 30 come into contact with the ground, while the track wheels 21a, 21b, including the flange 212, are raised above the ground, and in this state, the ground running device 30 is used to rotate the direction of the work vehicle 1 by 90° so that, in the illustrated example, the other end 2b of the chassis 2 faces in line with the extension of the other track 80b (Figures 8(B) to (C)).

[0071] The chassis 2 of the work vehicle 1 shown in Figures 3 to 5 is not only provided with a pair of swivel casters 31a, 31a; 31b, 31b at each of the one end 2a and the other end 2b of the chassis 2 as ground wheels, but also with a pair of fixed wheels 31c that can rotate independently at an intermediate position between the swivel caster 31a at one end 2a and the swivel caster 31b at the other end, so that the work vehicle 1 can turn with a small turning radius around the intermediate position C between the pair of fixed wheels 31c, 31c as shown in Figure 8(B).

[0072] After turning the work vehicle 1 in this way, the work vehicle 1 is pushed forward on the ground G to a position on the extension of the other track 80b (Fig. 8(C)-(D)).

[0073] Then, the work vehicle 1 is again rotated 90° around the midpoint C between the fixed wheels 31c, 31c, and the direction of the work vehicle 1 is changed so that the other end 2b of the chassis 2 faces the other track 80b (Figures 8(D) to (E)).

[0074] After the work vehicle 1 turns, the work vehicle 1 is driven toward the other track 80b until the tread surfaces 211 of the track wheels 21a, 21b run onto the other track 80b, causing the work vehicle 1 to run onto the other track (Figure 8(E)), and the movement of the work vehicle 1 from one track 80a to the other track 80b is completed.

[0075] The work vehicle described in Patent Document 2 cited above required the cumbersome task of using a lifting mechanism to raise and lower the casters 50 each time the work vehicle 100 was turned, but the work vehicle 1 of the present invention does not require such cumbersome work and can be moved relatively easily from one track 80a to another track 80b.

[0076] Moreover, since the work vehicle 1 of Example 1 has a small turning radius, it is possible to change direction and move the work vehicle 1 in a narrow space.

[0077] Furthermore, the illustrated work vehicle is constructed with a deck 4 surrounded by a protective fence 5, so that when traveling on the ground, the work vehicle 1 can be easily operated to move forward, backward, turn, etc. by holding onto this protective fence 5 and traveling along the ground.

[0078] (2) Example 2 (Figure 6) In the work vehicle 1 of Example 1 described with reference to Figure 5, the ground running device 30 is configured to have swivel casters 31a and 31b as well as a fixed wheel 31c positioned midway between the swivel casters 31a and 31b.

[0079] In contrast, the work vehicle 1 of Example 2 shown in Figure 6 differs from the configuration of the ground running device 30 of the work vehicle 1 of Example 1 in that it does not have fixed wheels 31c, and the ground wheels are composed only of swivel casters 31a, 31b.

[0080] In this configuration, as shown in Figure 9, after the work vehicle 1 is lowered from one track 80a to the ground G, the work vehicle 1 is moved in a direction perpendicular to the longitudinal direction of the first track 80a, and then the work vehicle 1 is driven toward the other track 80b and mounted on the other track 80b, thereby completing the movement and eliminating the need to rotate the work vehicle 1.

[0081] In this way, if the ground running device 30 is composed only of swivel casters 31a, 31b, the freedom of movement of the work vehicle 1 when running on the ground increases, but the lack of fixed wheels reduces the stability of the work vehicle 1 when running straight, and in particular, if the ground is inclined, it becomes difficult to run in a direction that intersects with the direction of the inclination.

[0082] Therefore, when the ground wheels that make up the ground running device 30 are composed only of swivel casters 31a, 31b, at least one of these, and preferably two or more, may be swivel casters equipped with a stopper mechanism (not shown) that fixes the yoke so that it cannot turn at any position and enables this fixation to be released, and when running in a straight line, the yoke of the swivel caster may be run in a state where it is fixed so that it cannot turn, thereby enabling straight running in a stable state.

[0083] In addition, the use of such a swivel caster with a stopper mechanism can also be used for the swivel casters 31a and 31b of the ground running device of Example 1 described with reference to Figure 5, and can also be used for the swivel caster 31a of the work vehicle of Example 3 described later in Figure 7.

[0084] (3) Example 3 (Figure 7) In the work vehicle 1 of Example 2 described with reference to Figure 6, a pair of ground wheels 31a, 31a; 31b, 31b provided on one end 2a and the other end 2b of the chassis 2, respectively, are configured as swivel casters.

[0085] In contrast, the work vehicle 1 of Example 3 shown in Figure 7 has a configuration different from that of the work vehicle 1 of Example 2 (Figure 6) in that a pair of ground wheels 31a, 31a provided on one end 2a of the chassis 2 are formed as swivel casters, while a pair of ground wheels provided on the other end 2b of the chassis are formed as fixed wheels 31b', 31b' whose rotation direction is fixed in the same direction as the track wheels 21a, 21b.

[0086] In this way, by making the ground wheels provided on one end 2a or the other end 2b of the chassis 2 (in Figure 7, the ground wheels on the other end 2b side) fixed wheels 31b', the turning radius of the work vehicle 1 becomes larger, but straight-line stability can be improved.

[0087] Furthermore, in comparison with the configuration of the work vehicle 1 of Example 1 (Fig. 5), the number of ground wheels is reduced, which makes it possible to simplify the device configuration and reduce manufacturing costs.

[0088] In the work vehicle 1 of Figure 7 configured in this manner, the work vehicle 1 can be moved from one track 80a to another track 80b by a process similar to that described in Figure 8 for the operation of the work vehicle 1 of Example 1 (Figure 5), except that direction changes while traveling on the ground are centered around the intermediate position C' of the fixed wheel 31b' provided on the other end 2b side of the chassis 2 as shown in Figure 10. [Explanation of symbols]

[0089] 1,100 (Gardening) Work vehicle (rail-running type) 2,102 chassis 2a One end (of the chassis) 2b Other end (of chassis) 3 Lifting mechanism (scissor link mechanism) 4 Decks 5 Protective fence 10 Running gear 20 Track running gear 21a Track wheels (on one end of the chassis) 21b Track wheels (on the other end of the chassis) 211 Tread 212,212' flange 22 Drive motor 23 axles 30 Ground running gear 31a Ground wheels / swivel casters (on one end of the chassis) 31b Ground wheels / swivel casters (on the other end of the chassis) 31b' Ground wheels / fixed wheels (on the other end of the chassis) 31c ground wheels / fixed wheels 311 Yoke (for swivel casters) 312 Wheels (swivel casters) 40,50 wheels 40a,50a front wheel 40b,50b rear wheel 45 Disc 46 Steering mechanism 47 Handle 51 Caster 80 orbit 80a First Orbit 80b Other orbits 81 Circulation pipe (longitudinal direction of track) 82 Part that connects the ends of the track in the width direction 90 Gardening greenhouse 91 Planting Department 92 Passage H Height difference (between the lowest point P2 of the tread of the track wheel that comes into contact with the top surface of the track and the lowest point P1 of the ground wheel) δ Height difference (between the lowest point P3 of the track wheel flange and the lowest point P1 of the ground wheel) W1 Outer width of the track W2 Inner distance between flanges of track wheels G ground P1 lowest point of ground wheels P2 The lowest point of the tread of the track wheel that comes into contact with the top surface of the track P3 Lowest point of track wheel flange P4 Lowest point of fixed wheels (for ground travel)

Claims

1. A track-traveling work vehicle that can travel on a pair of tracks arranged parallel to the ground by a running device installed on the chassis, The traveling device includes a track traveling device for performing track traveling on the track, and a ground traveling device for performing ground traveling on the ground, The track running device is provided with a pair of track wheels, each of which has a tread placed on the track and a flange protruding from an end of the tread in the width direction toward the periphery, at one end and the other end of the chassis in the track running direction, and is also provided with a drive motor that drives at least one of the track wheels, The ground running device is provided with a pair of rotatable ground wheels at least at each of the one end side and the other end side of the chassis, which enable the ground running, at positions where they do not interfere with the track when running on the track, The pair of ground wheels provided on at least one side of the one end side or the other end side of the chassis are swivel casters, A track-running work vehicle characterized in that the difference in height between the lowest point of the part of the tread of the track wheel that comes into contact with the upper surface of the track and the lowest point of the ground wheel is equal to or less than the outer diameter of the pipe that constitutes the track, and the lowest point of the ground wheel is located at a position lower than the lowest point of the flange of the track wheel.

2. 2. A track-traveling work vehicle according to claim 1, wherein both of said pair of ground wheels on said one end side and said other end side of said chassis are swivel casters.

3. 2. A track-traveling work vehicle according to claim 1, characterized in that the swivel caster is provided with a stopper mechanism that fixes the yoke of the swivel caster so that it cannot turn at any turning position and that can release this fixation.

4. The ground running device is provided with a pair of rotatable fixed wheels for ground running, the rotation direction of which is fixed in the same rotation direction as the track wheels, at an intermediate position between the pair of ground wheels provided on the one end side of the chassis and the pair of ground wheels provided on the other end side of the chassis, 3. A track-running work vehicle according to claim 2, wherein the fixed wheels are positioned so as not to interfere with the track when the vehicle is running on the track, and the lowest points of the fixed wheels are at the same height as the lowest points of the pair of ground wheels provided on the one end and the other end of the chassis.

5. 5. A track-traveling work vehicle according to claim 1, further comprising a deck on the chassis on which a worker can board, and a lifting mechanism for raising and lowering the deck.

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