Transport vehicle

Abstract

In this transport vehicle, a fork is disposed so as to protrude rearward from a lifting device. A vehicle body is provided with a body portion for supporting a travel drive device (5) and a pair of leg portions disposed so as to protrude rearward from the body portion on both sides in the width direction with respect to the lifting trajectory of the fork. A drive wheel (41) and a rotation detection device (6) for detecting the rotation of the drive wheel (41) are supported by the travel drive device (5). The rotation detection device (6) comprises a driven roller (61) that is disposed so as to be in contact with the outer peripheral surface of the drive wheel (41) and rotates in response to the rotation of the drive wheel (41), and a rotation sensor that detects the rotation of the driven roller (61). A rotational axis (A2) of the driven roller (61) is disposed above a rotational axis (A1) of the drive wheel (41) and at a position in a traveling direction (T) different from the rotational axis (A1) of the drive wheel (41).

Description

Transport Vehicle

[0001] The present invention relates to a transport vehicle.

[0002] Patent Document 1 below discloses a transport vehicle (1) including a drive wheel (7), a traveling drive device (6) that drives the drive wheel (7), and a rotation detection device that detects the rotation of the drive wheel (7). Note that the reference numerals shown in parentheses in the description of the background art are those of Patent Document 1.

[0003] Japanese Patent Application Laid-Open No. 2007-293389

[0004] In the transport vehicle (1) of Patent Document 1, the rotation detection device includes a first gear (8) that rotates integrally with the drive wheel (7), a second gear (9) that meshes with the first gear (8), a third gear (10) having an outer diameter different from that of the first gear (8) and meshing with the second gear (9), and a rotation sensor (19) that detects the rotation of the third gear (10).

[0005] Therefore, a relatively large space needs to be secured for the arrangement of the above rotation detection device, leading to an increase in the size of the transport vehicle (1).

[0006] Thus, in a configuration including a rotation detection device, it is desired to realize a transport vehicle that is easy to miniaturize.

[0007] In view of the above, the characteristic configuration of the transport vehicle is as follows: a transport vehicle comprising: forks for supporting a pallet; a lifting device for raising and lowering the forks; a plurality of wheels including a drive wheel; a driving device for driving the drive wheel; and a vehicle body supporting the lifting device, the plurality of wheels, and the driving device, wherein a specific direction along the horizontal plane is defined as the front-rear direction, one side of the front-rear direction is defined as the front, the other side of the front-rear direction is defined as the rear, a direction along the horizontal plane that is perpendicular to the front-rear direction is defined as the width direction, a direction along the rotation axis of the drive wheel is defined as the axial direction, and a direction perpendicular to the axial direction when viewed in the vertical direction is defined as the travel direction; the forks are arranged to protrude from the lifting device toward the rear; the vehicle body comprises a main body that supports the driving device, and a pair of legs arranged on both sides in the width direction with respect to the lifting trajectory of the forks so as to protrude from the main body toward the rear; and further comprises a rotation detection device for detecting the rotation of the drive wheel. The drive wheel and the rotation detection device are supported by the travel drive unit, and the rotation detection device comprises a driven roller arranged to contact the outer circumferential surface of the drive wheel and to rotate in conjunction with the rotation of the drive wheel, and a rotation sensor for detecting the rotation of the driven roller, wherein the rotation axis of the driven roller is located above the rotation axis of the drive wheel and is positioned in a different direction from the rotation axis of the drive wheel in the direction of travel.

[0008] This configuration allows the driven rollers of the rotation detection device to be positioned in the space formed diagonally above the drive wheels. This makes it easier to suppress the increase in size of the transport vehicle that would otherwise be required to accommodate the rotation detection device. In other words, it is easier to miniaturize the transport vehicle in a configuration that includes a rotation detection device.

[0009] Perspective view of the transport vehicle according to the embodiment Bottom view of the transport vehicle according to the embodiment Plan cross-sectional view of the transport vehicle according to the embodiment Plan cross-sectional view showing the configuration of the travel drive system and rotation detection device Side view showing the configuration of the travel drive system and rotation detection device

[0010] In the following description, the transport vehicle 100 according to the embodiment will be explained with reference to the drawings.

[0011] As shown in Figures 1 and 2, the transport vehicle 100 comprises a fork 1, a lifting device 2, a vehicle body 3, a plurality of wheels 4, and a driving device 5.

[0012] In the following description, a specific direction along the horizontal plane will be referred to as the "front-rear direction D". One side of the front-rear direction D will be referred to as the "front side D1", and the other side of the front-rear direction D will be referred to as the "rear side D2". Furthermore, a direction along the horizontal plane that is perpendicular to the front-rear direction D will be referred to as the "width direction W". In this application, the "vertical direction" refers to the vertical direction when the transport vehicle 100 is positioned on a horizontal plane.

[0013] The fork 1 is configured to support the pallet P. The fork 1 is positioned to protrude from the lifting device 2 toward the rear D2. In this embodiment, a pair of forks 1 are arranged side by side with a gap between them in the width direction W. As the pallet P, various existing pallets commonly used in the logistics industry can be used.

[0014] As shown in Figures 1 and 3, the lifting device 2 is a device for raising and lowering the fork 1. In this embodiment, the lifting device 2 comprises a pair of lifting rails 21, a pair of lifting rollers 22, a pair of roller support members 23, a fork connecting member 24, a lifting member 25, a lifting drive device 26, and a pair of chains 27.

[0015] Each of the pair of lifting rails 21 is formed to extend along the vertical direction. The pair of lifting rails 21 are arranged side by side with a gap between them in the width direction W.

[0016] Each of the pair of lifting rollers 22 is configured to roll along the lifting rail 21. In this embodiment, each of the pair of lifting rollers 22 is configured to rotate freely around a rotation axis along the width direction W. Each of the pair of lifting rollers 22 is arranged to roll on a pair of rolling surfaces on the lifting rail 21 that face each other in the front-rear direction D.

[0017] Each of the pair of roller support members 23 is a member that rotatably supports the lifting roller 22. In this embodiment, each of the pair of roller support members 23 is formed in a plate shape perpendicular to the width direction W.

[0018] The fork connecting member 24 is the member to which the forks 1 are connected. A pair of roller support members 23 are fixed to the fork connecting member 24. In this embodiment, the fork connecting member 24 is formed in a plate shape perpendicular to the front-rear direction D.

[0019] The lifting member 25 is a member that is raised and lowered by a lifting drive device 26 via a pair of chains 27. The lifting member 25 is connected to a fork connecting member 24. Therefore, as the lifting member 25 moves up and down, the fork 1 moves up and down via the fork connecting member 24. In this embodiment, the lifting member 25 is formed in the shape of a plate perpendicular to the vertical direction.

[0020] As shown in Figure 1, the lifting drive device 26 is a device that raises and lowers a lifting member 25 via a pair of chains 27. In this embodiment, the lifting drive device 26 comprises a pair of sprockets (not shown) around which the pair of chains 27 are wound, and a lifting drive source (not shown) that rotates the pair of sprockets.

[0021] In this embodiment, one end of a pair of chains 27 is connected to a lifting member 25. Although not shown in the figures, the other end of the pair of chains 27 is connected to a pair of forks 1, a pair of lifting rollers 22, a pair of roller support members 23, a fork connecting member 24, and a counterweight that balances the lifting member 25.

[0022] As shown in Figure 2, the vehicle body 3 is configured to support the lifting device 2, a plurality of wheels 4, and the driving device 5. The vehicle body 3 comprises a main body 31 and a pair of legs 32.

[0023] The main body 31 is configured to support the travel drive unit 5. In this embodiment, the main body 31 includes a swivel support section 311 and a pair of rail support sections 312.

[0024] The swivel support section 311 is configured to support the travel drive unit 5 so that it can rotatably support it around a swivel axis C1 that is aligned in the vertical direction. In this embodiment, the swivel support section 311 comprises a fixed section 313 and a swivel section 314.

[0025] The swivel section 314 is supported by the fixed section 313 so as to be able to rotatably around the swivel axis C1. In this embodiment, the swivel section 314 is formed in the shape of an annular plate with the swivel axis C1 as the center. The fixed section 313 is formed in the shape of a plate perpendicular to the swivel axis C1.

[0026] As shown in Figure 3, the pair of rail support sections 312 are configured to support the pair of lifting rails 21. The pair of rail support sections 312 are arranged separately on both sides in the width direction W relative to the swivel support section 311. In this embodiment, the pair of rail support sections 312 are fixed to the fixing section 313. In addition, in this embodiment, each of the pair of rail support sections 312 is provided with a fixing wall 315.

[0027] Each of the pair of fixed walls 315 is formed to extend along the vertical direction. A lifting rail 21 is fixed to each of the pair of fixed walls 315. In this embodiment, each of the pair of fixed walls 315 is formed in the shape of a plate perpendicular to the front-rear direction D. Each of the pair of fixed walls 315 is fixed to the lifting rail 21 in a state where it is in contact with the lifting rail 21 from the front side D1.

[0028] The pair of legs 32 are positioned on both sides in the width direction W with respect to the lifting trajectory of the fork 1. The pair of legs 32 are formed to protrude from the main body 31 toward the rear side D2. In this embodiment, each of the pair of legs 32 has a hollow structure.

[0029] As shown in Figure 2, the plurality of wheels 4 include drive wheels 41. In this embodiment, the plurality of wheels 4 include a pair of drive wheels 41 and two pairs of driven wheels 42.

[0030] In the following explanation, the direction along the rotation axis of the drive wheel 41 will be referred to as the "axial direction L". Furthermore, the direction perpendicular to the axial direction L when viewed from above and below will be referred to as the "travel direction T".

[0031] The drive wheels 41 are among the multiple wheels 4 and are driven by the travel drive unit 5. The drive wheels 41 are supported by the travel drive unit 5. In this embodiment, a pair of drive wheels 41 are arranged coaxially. The pair of drive wheels 41 are arranged side by side with a gap between them in the axial direction L.

[0032] The driven wheels 42 are among the multiple wheels 4 that are not driven by the drive unit including the travel drive unit 5. In this embodiment, a pair of driven wheels 42 are rotatably supported on each of the pair of legs 32. The pair of driven wheels 42 supported on each of the pair of legs 32 are arranged coaxially so as to be spaced apart from each other in the width direction W. In the example shown in Figure 2, the pair of driven wheels 42 are supported on each of the pair of legs 32 in the portion D2 behind the lifting device 2.

[0033] In this embodiment, the difference in rotation of the pair of drive wheels 41 causes the travel drive unit 5, to which the pair of drive wheels 41 are supported, to rotate around the pivot axis C1. When the travel drive unit 5 is rotated at a 90° angle, the pair of drive wheels 41 are driven to rotate, causing the transport vehicle 100 to rotate around the vehicle pivot axis C2 which is aligned vertically. In this embodiment, the vehicle pivot axis C2 is positioned so as to pass through an intermediate position in the width direction W between the pair of driven wheels 42 supported by one leg portion 32 and the pair of driven wheels 42 supported by the other leg portion 32 (a position equally spaced from the pair of driven wheels 42) on the rotation axis of the two pairs of driven wheels 42. The "rotation angle of the travel drive unit 5" is the angle at which the rotation axis of the drive wheels 41 intersects the width direction W.

[0034] The travel drive unit 5 is a device that drives the drive wheels 41. As shown in Figures 4 and 5, in this embodiment, the travel drive unit 5 includes a pair of first support members 51, a second support member 52, a third support member 53, and a pair of travel drive sources 54.

[0035] The pair of first support members 51 are connected to the swivel section 314 so as to rotate integrally with the swivel section 314. The pair of first support members 51 are arranged separately on both sides in the travel direction T with respect to the swivel axis C1. In this embodiment, each of the pair of first support members 51 is formed in a plate shape perpendicular to the travel direction T. The pair of first support members 51 are arranged to extend downward from the swivel section 314.

[0036] The second support member 52 extends along the travel direction T so as to pass through the pivot axis C1. The second support member 52 is positioned to connect the pair of first support members 51.

[0037] The third support member 53 is configured to support a pair of travel drive sources 54. The third support member 53 is positioned between the pair of first support members 51 in the travel direction T. The third support member 53 is supported by the pair of first support members 51. In this embodiment, the third support member 53 includes a pair of first wall portions 531 and a pair of second wall portions 532.

[0038] Each of the pair of first wall portions 531 is formed in a plate shape perpendicular to the travel direction T. The pair of first wall portions 531 are arranged to face each other with a gap between them in the travel direction T. Each of the pair of first wall portions 531 is connected to a pair of first support members 51.

[0039] Each of the pair of second wall portions 532 is formed in a plate shape perpendicular to the axial direction L. The pair of second wall portions 532 are arranged to face each other with a gap between them in the axial direction L. Each of the pair of second wall portions 532 supports a pair of drive sources 54. In this embodiment, a pair of drive wheels 41 are arranged separately on both sides of the pair of second wall portions 532 in the axial direction L.

[0040] Each of the pair of drive sources 54 is a drive source for a pair of drive wheels 41. The pair of drive sources 54 are configured to drive the pair of drive wheels 41 independently of each other. The pair of drive sources 54 are spaced apart from each other in the axial direction L. Each of the pair of drive sources 54 is supported by a pair of second wall portions 532. In this embodiment, each of the pair of drive sources 54 is an electric motor.

[0041] As shown in Figures 4 and 5, the transport vehicle 100 is equipped with a rotation detection device 6. The rotation detection device 6 is a device that detects the rotation of the drive wheels 41. In this embodiment, the transport vehicle 100 is equipped with a pair of rotation detection devices 6 in order to detect the rotation of a pair of drive wheels 41.

[0042] The rotation detection device 6 is supported by the drive unit 5. The rotation detection device 6 includes a driven roller 61 and a rotation sensor 62. The driven roller 61 is a roller that rotates in conjunction with the rotation of the drive wheel 41. The driven roller 61 is positioned so as to be in contact with the outer circumferential surface of the drive wheel 41. The rotation sensor 62 is a sensor that detects the rotation of the driven roller 61. In this embodiment, the rotation sensor 62 is an encoder.

[0043] As shown in Figure 5, the rotation axis of the driven roller 61 is located above the rotation axis of the drive wheel 41 and is positioned at a different location in the direction of travel T from the rotation axis of the drive wheel 41. In Figure 5, "A1" is the rotation axis of the drive wheel 41 and "A2" is the rotation axis of the driven roller 61.

[0044] In this embodiment, the rotation axis of the driven roller 61 is disposed within at least one of the following ranges: within a range below the upper end of the outer peripheral surface of the drive wheel 41 and within a range between both ends in the traveling direction T on the outer peripheral surface of the drive wheel 41. In the example shown in FIG. 5, the rotation axis of the driven roller 61 is disposed within both of the following ranges: within a range below the upper end of the outer peripheral surface of the drive wheel 41 and within a range between both ends in the traveling direction T on the outer peripheral surface of the drive wheel 41. In FIG. 5, “L1” is a dashed line indicating the position of the upper end of the outer peripheral surface of the drive wheel 41. Further, “L2” is a dashed line indicating the position of one end in the traveling direction T on the outer peripheral surface of the drive wheel 41, and “L3” is a dashed line indicating the position of the other end in the traveling direction T on the outer peripheral surface of the drive wheel 41.

[0045] In this embodiment, a driven roller 61 is disposed on each of the pair of drive wheels 41. The pair of driven rollers 61 are disposed separately on both sides in the traveling direction T with respect to the rotation axes of the pair of drive wheels 41.

[0046] In this embodiment, the rotation detection device 6 is disposed below the bottom surface 311a of the turning support portion 311 and above the rotation axis of the drive wheel 41. The bottom surface 311a is a surface facing the lower side of the turning support portion 311. In this embodiment, the bottom surface 311a is the lower end surface of the turning portion 314.

[0047] As shown in FIG. 4, in this embodiment, a pair of rotation sensors 62 are disposed to detect the rotation of the pair of driven rollers 61, respectively. In this embodiment, a sensor such as an encoder for detecting the rotation of the output element of the traveling drive source 54 is mounted on the traveling drive source 54. The rotation sensor 62 is provided independently of the sensor mounted on the traveling drive source 54. According to such a configuration, since the traveling state of the transport vehicle 100 can be monitored doubly, it is easy to improve the accuracy and safety of the traveling control of the transport vehicle 100.

[0048] In this embodiment, the rotation detection device 6 further includes a pair of fixed members 63. The pair of fixed members 63 are respectively fixed to the pair of second wall portions 532. A driven roller 61 and a rotation sensor 62 are supported on each of the pair of fixed members 63. In this embodiment, the driven roller 61 and the rotation sensor 62 are arranged separately in the axial direction L with respect to the fixed member 63.

[0049] Also, in this embodiment, the rotation detection device 6 is arranged inside the outer edge of the turning locus of the drive wheel 41 (refer to the dashed line in FIG. 4) when the traveling drive device 5 turns around the turning axis C1 in a top-down view.

[0050] As shown in FIG. 4, in this embodiment, the transport vehicle 100 further includes a turning position sensor 7.

[0051] The turning position sensor 7 is a sensor that detects whether the turning angle of the traveling drive device 5 with respect to the width direction W is within a set angle range including 90°. The set angle range is set to, for example, 90 ± 20°. In this embodiment, a pair of detected portions 71 that extend away from each other in the traveling direction T from the pair of first support members 51 are provided. The pair of detected portions 71 turn as the traveling drive device 5 turns. In this embodiment, when the turning position sensor 7 detects any one of the pair of detected portions 71, it is determined that the turning angle of the traveling drive device 5 is within the above set angle range. Also, in this embodiment, the turning position sensor 7 is supported by the rail support portion 312 of the main body portion 31.

[0052] [Other Embodiments] (1) In the above embodiment, the rotation axis of the driven roller 61 was described as being located in both the range below the upper end of the outer circumferential surface of the drive wheel 41 and the range between the two ends of the running direction T on the outer circumferential surface of the drive wheel 41. However, the configuration is not limited to such an embodiment, and for example, the rotation axis of the driven roller 61 may be located in either the range below the upper end of the outer circumferential surface of the drive wheel 41 or the range between the two ends of the running direction T on the outer circumferential surface of the drive wheel 41. Alternatively, the rotation axis of the driven roller 61 may be located above the rotation axis of the drive wheel 41 and at a different position in the running direction T from the rotation axis of the drive wheel 41, and does not have to be located in either the range below the upper end of the outer circumferential surface of the drive wheel 41 or the range between the two ends of the running direction T on the outer circumferential surface of the drive wheel 41.

[0053] (2) In the above embodiment, the pair of driven rollers 61 were described as being arranged on both sides in the travel direction T with respect to the rotation axis of the pair of drive wheels 41. However, the system is not limited to such a configuration, and the pair of driven rollers 61 may be arranged on one side in the travel direction T with respect to the rotation axis of the pair of drive wheels 41.

[0054] (3) In the above embodiment, a configuration in which the travel drive unit 5 rotates around the pivot axis C1 by the difference in rotation of a pair of drive wheels 41 was described as an example. However, the configuration is not limited to such a configuration, and for example, a configuration in which a drive unit is provided to rotate the travel drive unit 5 around the pivot axis C1 may also be used. In this configuration, there may be only one drive wheel 41.

[0055] (4) In the above embodiment, a configuration in which multiple wheels 4 include drive wheels 41 and driven wheels 42 was described as an example. However, the system is not limited to such a configuration, and for example, all wheels 4 may be drive wheels 41.

[0056] (5) In the above embodiment, a configuration in which a pair of forks 1 are arranged side by side with a gap between them in the width direction W was described as an example. However, the configuration is not limited to such a configuration, and a configuration with one fork 1 or three or more forks 1 may also be used.

[0057] (6) The configurations disclosed in each of the embodiments described above can be applied in combination with configurations disclosed in other embodiments, as long as no inconsistencies arise. With regard to other configurations, the embodiments disclosed herein are merely illustrative in all respects. Therefore, various modifications can be made as appropriate, without departing from the spirit of this disclosure.

[0058] [Summary of this embodiment] The following describes the outline of the transport vehicle described above.

[0059] The transport vehicle comprises: forks for supporting a pallet; a lifting device for raising and lowering the forks; a plurality of wheels including a drive wheel; a drive unit for driving the drive wheel; and a vehicle body supporting the lifting device, the plurality of wheels, and the drive unit, wherein a specific direction along the horizontal plane is defined as the front-rear direction, one side of the front-rear direction is defined as the front, the other side of the front-rear direction is defined as the rear, a direction along the horizontal plane that is perpendicular to the front-rear direction is defined as the width direction, a direction along the rotation axis of the drive wheel is defined as the axial direction, and a direction perpendicular to the axial direction when viewed in the vertical direction is defined as the travel direction; the forks are arranged to protrude from the lifting device toward the rear; the vehicle body comprises a main body that supports the drive unit, and a pair of legs arranged on both sides in the width direction with respect to the lifting trajectory of the forks, protruding from the main body toward the rear; and further comprises a rotation detection device for detecting the rotation of the drive wheel, the drive wheel and the rotation detection device are supported by the drive unit. The rotation detection device comprises a driven roller positioned so as to contact the outer circumferential surface of the drive wheel and rotating in conjunction with the rotation of the drive wheel, and a rotation sensor for detecting the rotation of the driven roller, wherein the rotation axis of the driven roller is located above the rotation axis of the drive wheel and is positioned in a different direction from the rotation axis of the drive wheel in the direction of travel.

[0060] This configuration allows the driven rollers of the rotation detection device to be positioned in the space formed diagonally above the drive wheels. This makes it easier to suppress the increase in size of the transport vehicle that would otherwise be required to accommodate the rotation detection device. In other words, it is easier to miniaturize the transport vehicle in a configuration that includes a rotation detection device.

[0061] Here, it is preferable that the rotation axis of the driven roller is located within at least one of the following ranges: below the upper end of the outer circumferential surface of the drive wheel, and between the two ends of the outer circumferential surface of the drive wheel in the direction of travel.

[0062] This configuration makes it easier to further miniaturize the transport vehicle in at least one of the vertical and horizontal directions.

[0063] Furthermore, it is preferable that the plurality of wheels include a pair of drive wheels arranged coaxially, with a driven roller positioned on each of the pair of drive wheels, and that the pair of driven rollers are positioned on both sides in the direction of travel with respect to the rotation axis of the pair of drive wheels.

[0064] This configuration allows the pair of rotation detection devices to have similar configurations, without requiring them to be symmetrically arranged in the axial direction. Therefore, it is possible to standardize parts between the pair of rotation detection devices, which in turn can reduce the cost of the transport vehicle.

[0065] Furthermore, the main body portion is preferably equipped with a swivel support portion that supports the travel drive device so as to be rotatable around a swivel axis along the vertical direction, and the rotation detection device is preferably positioned below the downward-facing bottom surface of the swivel support portion and above the rotation axis of the drive wheel.

[0066] This configuration allows for the placement of a rotation detection device in a space below the bottom surface of the swivel support, where it does not interfere with the drive wheels and the travel drive system. Therefore, it is easier to further miniaturize the transport vehicle.

[0067] In the above configuration, it is preferable that the rotation detection device is positioned inward from the outer edge of the turning trajectory of the drive wheel when the travel drive unit turns around the turning axis, as viewed from above.

[0068] This configuration makes it easier to miniaturize the transport vehicle in the direction perpendicular to the pivot axis of the drive wheels.

[0069] Furthermore, it is preferable that the transport vehicle is further equipped with a swivel position sensor that detects whether the swivel angle of the travel drive device in the width direction is within a set angle range including 90°.

[0070] This configuration allows for the detection, with a simple setup, of whether the drive wheels are being driven for straight-line movement of the transport vehicle or for changing the direction of the transport vehicle.

[0071] The technology disclosed herein can be used in transport vehicles.

[0072] 100: Transport vehicle 1: Fork 2: Lifting device 3: Vehicle body 31: Main body 311: Swivel support part 32: Legs 4: Wheels 41: Drive wheels 5: Travel drive device 6: Rotation detection device 61: Driven roller 62: Rotation sensor 7: Swivel position sensor P: Pallet C1: Swivel axis D: Front-rear direction D1: Front side D2: Rear side W: Width direction L: Axial direction T: Travel direction

Claims

1. A transport vehicle comprising: forks for supporting a pallet; a lifting device for raising and lowering the forks; a plurality of wheels including a drive wheel; a drive unit for driving the drive wheel; and a vehicle body supporting the lifting device, the plurality of wheels, and the drive unit, wherein a specific direction along a horizontal plane is defined as the front-rear direction, one side of the front-rear direction is defined as the front, the other side of the front-rear direction is defined as the rear, a direction along the horizontal plane that is perpendicular to the front-rear direction is defined as the width direction, a direction along the rotation axis of the drive wheel is defined as the axial direction, and a direction perpendicular to the axial direction when viewed in the vertical direction is defined as the travel direction; the forks are arranged to protrude from the lifting device toward the rear; the vehicle body comprises a main body that supports the drive unit, and a pair of legs arranged on both sides in the width direction with respect to the lifting trajectory of the forks, so as to protrude from the main body toward the rear; and further comprises a rotation detection device for detecting the rotation of the drive wheel; the drive wheel and the rotation detection device are supported by the drive unit. The rotation detection device comprises a driven roller positioned so as to be in contact with the outer circumferential surface of the drive wheel and rotating in conjunction with the rotation of the drive wheel, and a rotation sensor for detecting the rotation of the driven roller, wherein the rotation axis of the driven roller is located above the rotation axis of the drive wheel and is positioned in a different direction from the rotation axis of the drive wheel in the direction of travel.

2. The transport vehicle according to claim 1, wherein the rotation axis of the driven roller is located in at least one of the following ranges: below the upper end of the outer surface of the drive wheel, and between the two ends of the outer surface of the drive wheel in the direction of travel.

3. The transport vehicle according to claim 1 or 2, wherein the plurality of wheels include a pair of drive wheels arranged coaxially, each of the pair of drive wheels having a driven roller, and the pair of driven rollers are arranged separately on both sides in the direction of travel with respect to the rotation axis of the pair of drive wheels.

4. The transport vehicle according to claim 1 or 2, wherein the main body includes a pivot support portion that pivotably supports the travel drive device around a pivot axis along the vertical direction, and the rotation detection device is positioned below the downward-facing bottom surface of the pivot support portion and above the rotation axis of the drive wheel.

5. The transport vehicle according to claim 4, wherein the rotation detection device is positioned inward from the outer edge of the turning trajectory of the drive wheel when the travel drive unit turns around the turning axis, in the view from the up and down direction.

6. The transport vehicle according to claim 4, further comprising a turning position sensor for detecting whether the turning angle of the travel drive device in the width direction is within a set angle range including 90°.

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