Transport vehicle

Abstract

In this transport vehicle, a fork (1) is disposed so as to protrude from a lifting device (2) toward the rear side (D2). A vehicle body (3) is provided with a body portion (31) for supporting a traveling drive device, and a pair of leg portions (32) disposed so as to protrude from the body portion (31) toward the rear side (D2) on both sides in the width direction with respect to the lifting trajectory of the fork (1). A first obstacle sensor (91A) is disposed so as to protrude from the upper surface of a first leg portion (32A), which is one of the pair of leg portions (32). A second obstacle sensor (91B) is disposed so as to protrude from the upper surface of a second leg portion (32B), which is the other of the pair of leg portions (32). The first obstacle sensor (91A) and the second obstacle sensor (91B) are disposed so as to overlap the lifting device (2) in a width-direction view along the width direction (W).

Description

Transport Vehicle

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

[0002] In Patent Document 1 below, there is disclosed a transport vehicle (1) including a fork (60) that supports a pallet, a lifting device (70) that raises and lowers the fork (60), and an obstacle sensor (21F) that detects an obstacle existing around the vehicle body (3). Note that the reference numerals shown in parentheses in the description of the background art are those of Patent Document 1.

[0003] In the transport vehicle (1) of Patent Document 1, when traveling such that the fork (60) is positioned on the front side in the traveling direction, the obstacle sensor (21F) detects an obstacle existing on the front side in the traveling direction.

[0004] Japanese Patent Application Laid-Open No. 2019-105995

[0005] However, in the transport vehicle (1) of Patent Document 1, since the obstacle sensor (21F) is disposed in the vicinity of the fork (60), for example, when the pallet is not properly supported by the fork (60), the pallet may contact the obstacle sensor (21F), and there is a possibility that the obstacle sensor (21F) may be damaged.

[0006] Therefore, it is desired to realize a transport vehicle that is less likely to avoid contact between the pallet supported by the fork and the obstacle sensor.

[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; a vehicle body supporting the lifting device, the plurality of wheels, and the driving device; and a control device for controlling the lifting device 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 side, the other side of the front-rear direction is defined as the rear side, and a direction along the horizontal plane that is perpendicular to the front-rear direction is defined as the width direction; the forks are arranged to protrude from the lifting device toward the rear side; 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 side; and further comprising a first obstacle sensor and a second obstacle sensor for detecting obstacles present around the vehicle body. The first obstacle sensor is positioned to protrude from the upper surface of the first leg, which is one of the pair of legs, and the second obstacle sensor is positioned to protrude from the upper surface of the second leg, which is the other of the pair of legs. The first and second obstacle sensors are positioned so as to overlap with the lifting device when viewed in the width direction along the width direction.

[0008] In this configuration, the first and second obstacle sensors are positioned so as to overlap with the lifting device in a widthwise view along the width direction. This allows the first and second obstacle sensors to be positioned away from the front of the fork tip. Therefore, it is easier to avoid the pallet supported by the fork coming into contact with at least one of the first and second obstacle sensors when the pallet is not properly supported by the fork. Furthermore, in this configuration, the first obstacle sensor is positioned so as to protrude from the upper surface of the first leg, and the second obstacle sensor is positioned so as to protrude from the upper surface of the second leg. This ensures that the detection areas of the first and second obstacle sensors are secured. Even in this configuration, as described above, since the first and second obstacle sensors are positioned so as to overlap with the lifting device in a widthwise view, it is possible to avoid the pallet coming into contact with at least one of the first and second obstacle sensors.

[0009] A perspective view of the transport vehicle according to the first embodiment. A bottom view of the transport vehicle according to the first embodiment. A plan cross-sectional view of the transport vehicle according to the first embodiment. A side view of the transport vehicle according to the first embodiment. A plan cross-sectional view showing the configuration of the travel drive system and rotation detection device of the transport vehicle according to the first embodiment. A perspective view showing the first obstacle sensor and second obstacle sensor, etc., of the transport vehicle according to the first embodiment. A perspective view showing the third obstacle sensor, etc., of the transport vehicle according to the first embodiment. A perspective view of the transport vehicle according to the second embodiment viewed from the rear. A plan view of the transport vehicle according to the second embodiment. A front view of the transport vehicle according to the second embodiment. A side view of the transport vehicle according to the second embodiment. A perspective view of the transport vehicle according to the second embodiment viewed from the front.

[0010] 1. In the following first embodiments, the transport vehicle 100 according to the first embodiment will be described with reference to Figures 1 to 7.

[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 positioned to roll on a rolling surface on the lifting rail 21 facing 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 the shape of a plate 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. The other end of the pair of chains 27 is connected to a counterweight 28 (see Figure 4) via a weight connecting member 281. The counterweight 28 is a member for balancing the pair of forks 1, the pair of lifting rollers 22, the pair of roller support members 23, the fork connecting member 24, and the lifting member 25. The weight connecting member 281 rotatably supports the weight roller 29. The weight roller 29 is arranged to roll on a rolling surface facing the front-rear direction D on the lifting rail 21. In this embodiment, one pair of weight rollers 29 rolls on the rolling surface of one lifting rail 21, while another pair of weight rollers 29 rolls on the rolling surface of the other lifting rail 21. In this embodiment, on each of the pair of lifting rails 21, the rolling surface of the weight roller 29 is located on the opposite side in the width direction W from the rolling surface of the lifting roller 22 (see Figure 3).

[0022] As shown in Figures 3 and 4, 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. In this embodiment, the vehicle body 3 further comprises a cover 33 (see also Figure 1).

[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, a pair of lower rail support sections 312, and an upper rail support section 313.

[0024] As shown in Figure 3, 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.

[0025] The pair of lower rail support sections 312 are configured to support the lower parts of the pair of lifting rails 21. The pair of lower 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, each of the pair of lower rail support sections 312 is provided with a fixed wall 314.

[0026] As shown in Figure 4, each of the pair of fixed walls 314 is formed to extend along the vertical direction. A lifting rail 21 is fixed to each of the pair of fixed walls 314. In this embodiment, each of the pair of fixed walls 314 is formed in the shape of a plate perpendicular to the front-rear direction D. Each of the pair of fixed walls 314 is fixed to the lifting rail 21 in a state where it is in contact with the lower part of the lifting rail 21 from the front side D1.

[0027] The upper rail support portion 313 is configured to support the upper parts of the pair of lifting rails 21. In this embodiment, the upper rail support portion 313 is formed in the shape of a plate perpendicular to the vertical direction. The upper rail support portion 313 is fixed to the pair of lifting rails 21 in a state where it is in contact with the upper ends of the pair of lifting rails 21 from above.

[0028] As shown in Figure 3, 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. Hereinafter, one of the pair of legs 32 will be referred to as the "first leg 32A" and the other as the "second leg 32B".

[0029] As shown in Figure 1, the cover 33 is formed to cover the main body 31. In this embodiment, the cover 33 is formed so as not to interfere with the lifting trajectories of the pair of forks 1, as well as the lifting trajectories of the pair of roller support members 23, fork connecting member 24, and lifting member 25 of the lifting device 2.

[0030] 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.

[0031] 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".

[0032] 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.

[0033] 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.

[0034] 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.

[0035] The travel drive unit 5 is a device that drives the drive wheels 41. As shown in Figure 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.

[0036] The pair of first support members 51 are supported by the swivel support portion 311 so as to be able to rotatably around the swivel axis C1. The pair of first support members 51 are arranged separately on both sides of 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 the shape of a plate perpendicular to the travel direction T. The pair of first support members 51 are arranged to extend downward from the swivel support portion 311.

[0037] 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.

[0038] 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.

[0039] 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.

[0040] 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.

[0041] 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.

[0042] As shown in Figure 6, the transport vehicle 100 is equipped with a first obstacle sensor 91A and a second obstacle sensor 91B.

[0043] The first obstacle sensor 91A and the second obstacle sensor 91B are sensors that detect obstacles present around the vehicle body 3. In this embodiment, the first obstacle sensor 91A and the second obstacle sensor 91B are sensors that detect obstacles that intersect a first detection surface S1 that is aligned horizontally. The first obstacle sensor 91A and the second obstacle sensor 91B are arranged so that their respective first detection surfaces S1 are at the same height. In this embodiment, the first obstacle sensor 91A and the second obstacle sensor 91B are arranged, or the areas of their first detection surfaces S1 are set, so that their first detection surfaces S1 do not interfere with each other. The first detection surface S1 is a "detection surface" that indicates the area in which obstacles can be detected by the first obstacle sensor 91A and the second obstacle sensor 91B, respectively.

[0044] The first obstacle sensor 91A is disposed so as to protrude from the upper surface of the first leg portion 32A. The second obstacle sensor 91B is disposed so as to protrude from the upper surface of the second leg portion 32B. In the illustrated example, each of the first obstacle sensor 91A and the second obstacle sensor 91B is disposed inside the leg portion 32 so as to protrude upward from the upper surface thereof through a through hole that vertically penetrates the upper surface of the hollow leg portion 32 (see also FIG. 4). For example, a configuration in which the first obstacle sensor 91A is installed on the upper surface of the first leg portion 32A is included in the configuration of "the first obstacle sensor 91A is disposed so as to protrude from the upper surface of the first leg portion 32A", and a configuration in which the second obstacle sensor 91B is installed on the upper surface of the second leg portion 32B is included in the configuration of "the second obstacle sensor 91B is disposed so as to protrude from the upper surface of the second leg portion 32B".

[0045] As shown in FIGS. 4 and 6, the first obstacle sensor 91A and the second obstacle sensor 91B are disposed so as to overlap the lifting device 2 in a width direction view along the width direction W. In the illustrated example, the first obstacle sensor 91A and the second obstacle sensor 91B are disposed so as to overlap the lifting locus of the fork connecting member 24 of the lifting device 2 in a width direction view along the width direction W. Here, regarding the arrangement of two elements, "overlapping in a specific direction view" means that when a virtual straight line parallel to the line-of-sight direction is moved in each direction orthogonal to the virtual straight line, there is at least a part of a region where the virtual straight line intersects both of the two elements.

[0046] As shown in FIG. 4, in the present embodiment, the transport vehicle 100 further includes a control device 10. The control device 10 is a device that controls the lifting device 2 and the traveling drive device 5. In the present embodiment, the control device 10 is fixed to the vehicle body 3 so as to be located on the front side D1 with respect to the pair of lifting rails 21.

[0047] When the control device 10 drives the drive wheels 41 of the traveling drive device 5 so that the vehicle body 3 moves at least to the rear side D2, the control device 10 executes traveling avoidance control for controlling the lifting device 2 so that the fork 1 is positioned within the sensor avoidance range. Here, the "sensor avoidance range" is a range of the vertical position of the fork 1 in which the fork 1 and the pallet P supported by the fork 1 are above the respective first detection surfaces S1 of the first obstacle sensor 91A and the second obstacle sensor 91B. FIG. 4 shows a state in which the traveling avoidance control is being executed.

[0048] In the present embodiment, when the fork 1 does not support the pallet P, the control device 10 does not execute the traveling avoidance control. Further, when the control device 10 drives the drive wheels 41 of the traveling drive device 5 so that the vehicle body 3 moves to the front side D1, the control device 10 does not execute the traveling avoidance control. When the control device 10 does not execute the traveling avoidance control, the fork 1 is arranged at the reference height. The reference height is set, for example, to the height of the lower limit of the lifting range of the fork 1. In the present embodiment, in the traveling avoidance control, the fork 1 is raised from the reference height to a height at which the fork 1 is positioned within the sensor avoidance range. The reference height is a height at which the fork 1 is arranged above or below the first detection surface S1 of the first obstacle sensor 91A and the pallet P supported by the fork 1 intersects the first detection surface S1. Therefore, when the fork 1 does not support the pallet P, the first detection surface S1 of the first obstacle sensor 91A does not interfere with the fork 1 even if the traveling avoidance control is not executed.

[0049] As shown in FIG. 7, in the present embodiment, the transport vehicle 100 further includes a third obstacle sensor 92 and a measurement range sensor 93.

[0050] The third obstacle sensor 92 is a sensor that detects obstacles present around the vehicle body 3. The third obstacle sensor 92 is positioned on the front side D1 of the main body 31 of the vehicle body 3. In this embodiment, the third obstacle sensor 92 is configured to detect obstacles that intersect the second detection surface S2 which is aligned horizontally. In this embodiment, the third obstacle sensor 92 is fixed to the vehicle body 3 so as to protrude from the front side D1 of the cover 33. In the example shown in Figure 7, a slit aligned with the width direction W is formed in the cover 33 so that the second detection surface S2 of the third obstacle sensor 92 does not interfere with the cover 33. The second detection surface S2 is a detection surface that indicates the region in which obstacles can be detected by the third obstacle sensor 92.

[0051] The range sensor 93 is a sensor used in SLAM (Simultaneous Localization and Mapping), a technology for automated guided vehicles such as the transport vehicle 100 to travel automatically. As shown in Figure 4, in this embodiment, the range sensor 93 is positioned on the upper rail support portion 313 of the vehicle body 3 so as to protrude upward from the upper surface of the cover 33 through a through hole that penetrates the upper surface in the vertical direction.

[0052] As shown in Figure 6, in this embodiment, the transport vehicle 100 further includes a pair of first pallet detection sensors 94, a pair of second pallet detection sensors 95, a pair of third pallet detection sensors 96, a pair of first collision detection sensors 97, and a second collision detection sensor 98.

[0053] The pair of first pallet detection sensors 94 are a "pair of pallet detection sensors" that detect whether or not a pallet P is located within the region between the pair of legs 32 in the width direction W. Each of the pair of first pallet detection sensors 94 is positioned at the rear end D2 of the pair of legs 32.

[0054] In this embodiment, each of the pair of first pallet detection sensors 94 is a laser distance sensor that emits a laser beam B in a straight line. Each of the pair of first pallet detection sensors 94 is positioned inside the hollow leg portion 32 and emits the laser beam B toward the rear D2 through a through hole that penetrates the surface of the leg portion 32 facing the rear D2 in the front-rear direction D (see also Figure 4). In this embodiment, the control device 10 determines that the pallet P is located within the region between the pair of leg portions 32 in the width direction W if the pallet P is located between the pair of laser beams B in the width direction W without contact with the pair of laser beams B emitted by the pair of first pallet detection sensors 94.

[0055] The pair of second pallet detection sensors 95 are sensors that detect whether or not the pallet P is properly supported by the pair of forks 1. Each of the pair of second pallet detection sensors 95 is positioned on the pair of forks 1. In this embodiment, each of the pair of second pallet detection sensors 95 is positioned at the front end D1 of the pair of forks 1.

[0056] Furthermore, in this embodiment, each of the pair of second pallet detection sensors 95 includes a first dog 951 that is pressed downward by the pallet P and swings when the pallet P is supported in the appropriate position by the pair of forks 1, and a first microswitch 952 that detects the swing of the first dog 951 (see also Figure 4). The control device 10 determines that the pallet P is properly supported by the pair of forks 1 without tilting when both of the pair of first dogs 951 swing downward and the pair of first microswitches 952 detect their swing.

[0057] The pair of third pallet detection sensors 96 are sensors that detect whether or not the pallet P is properly supported by the pair of forks 1. Each of the pair of third pallet detection sensors 96 is positioned on the pair of forks 1. In this embodiment, each of the pair of third pallet detection sensors 96 is positioned at the front end D1 of the pair of forks 1, above the pair of second pallet detection sensors 95.

[0058] Furthermore, in this embodiment, each of the pair of third pallet detection sensors 96 includes a second dog 961 that is pressed forward D1 by the pallet P and swings when the pallet P is supported in an appropriate position by the pair of forks 1, and a second microswitch 962 that detects the swing of the second dog 961 (see also Figure 4). The control device 10 determines that the pallet P is supported by the pair of forks 1 in an appropriate position in the front-rear direction D when both of the pair of second dogs 961 swing forward D1 and the pair of second microswitches 962 detect their swing.

[0059] The pair of first collision detection sensors 97 are sensors for detecting collisions. Each of the pair of first collision detection sensors 97 is positioned at the tip of each of the pair of forks 1. In this embodiment, each of the pair of first collision detection sensors 97 includes a pressure-sensitive switch.

[0060] The second collision detection sensor 98 is a sensor for detecting collisions. The second collision detection sensor 98 is positioned to surround the vehicle body 3. In this embodiment, the second collision detection sensor 98 is positioned to cover the lower ends of the surfaces of the pair of legs 32 that face opposite each other in the width direction W, and the surface of the cover 33 that faces the front side D1, so as to form a U shape in plan view. In this embodiment, the second collision detection sensor 98 also includes a pressure-sensitive switch.

[0061] As shown in Figure 5, in this embodiment, the transport vehicle 100 further includes a rotation detection device 6 and a rotation position sensor 7.

[0062] 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 the pair of drive wheels 41.

[0063] 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.

[0064] In this embodiment, a pair of rotation sensors 62 are arranged to detect the rotation of a pair of driven rollers 61. In this embodiment, the travel drive source 54 is equipped with a sensor such as an encoder that detects the rotation of the output element of the travel drive source 54. The rotation sensors 62 are provided independently of the sensors mounted on the travel drive source 54. With this configuration, the travel state of the transport vehicle 100 can be monitored in a dual manner, making it easier to improve the accuracy and safety of the travel control of the transport vehicle 100.

[0065] In this embodiment, the rotation detection device 6 further comprises a pair of fixed members 63. Each of the pair of fixed members 63 is fixed to a 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 axially L apart with respect to the fixed members 63.

[0066] Furthermore, in this embodiment, the rotation detection device 6 is positioned inward from the outer edge of the turning trajectory of the drive wheel 41 when the travel drive unit 5 turns around the turning axis C1, when viewed from above. (See the dashed line in Figure 5.)

[0067] In this embodiment, the control device 10 changes the area of ​​the first detection surface S1 of the first obstacle sensor 91A and the second obstacle sensor 91B, and the area of ​​the second detection surface S2 of the third obstacle sensor 92, based on the rotation of a pair of driven rollers 61 detected by a pair of rotation sensors 62. For example, when the control device 10 drives the drive wheels 41 to the drive unit 5 so that the vehicle body 3 moves to the rear side D2 on at least one side in the width direction W, the control device 10 moves the first detection surface S1 of the first obstacle sensor 91A and the second obstacle sensor 91B to one side in the width direction W.

[0068] The swivel position sensor 7 is a sensor that detects whether the swivel angle of the travel drive unit 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 detectable parts 71 are provided that extend from a pair of first support members 51 so as to be spaced apart from each other in the travel direction T. The pair of detectable parts 71 swivel in conjunction with the swivel of the travel drive unit 5. In this embodiment, the control device 10 determines that the swivel angle of the travel drive unit 5 is within the above set angle range when the swivel position sensor 7 detects either of the pair of detectable parts 71. In this embodiment, the swivel position sensor 7 is supported by the lower rail support part 312 of the main body part 31.

[0069] 2. In the second embodiment and subsequent embodiments, the transport vehicle 100 according to the second embodiment will be described with reference to Figures 8 to 12. In this embodiment, the configuration of the lifting device 2 mainly differs from that of the first embodiment. The following description will focus on the differences from the first embodiment. Points that are not specifically described are the same as in the first embodiment.

[0070] As shown in Figures 8 and 9, in this embodiment, the lifting device 2 includes a pair of fixed rails 211, a pair of movable rails 212, a pair of first rollers 221, and a pair of second rollers 222, instead of a pair of lifting rails 21 and a pair of lifting rollers 22. Also, in this embodiment, a counterweight 28 is not provided.

[0071] Each of the pair of fixed rails 211 is formed to extend along the vertical direction. The pair of fixed rails 211 are arranged side by side with a gap between them in the width direction W. The pair of fixed rails 211 are fixed to the main body 31. In this embodiment, the pair of fixed rails 211 are arranged on both sides in the width direction W, with the travel drive unit 5 in between.

[0072] Each of the pair of movable rails 212 is formed to extend along the vertical direction. Each of the pair of movable rails 212 is supported so as to be movable in the vertical direction relative to the fixed rail 211.

[0073] As shown in Figure 9, each of the pair of first rollers 221 is rotatably supported with respect to the fixed rail 211. Each of the pair of first rollers 221 is configured to roll on a rolling surface formed on the movable rail 212 that extends vertically as the movable rail 212 moves vertically.

[0074] Each of the pair of second rollers 222 is rotatably supported on the roller support member 23. Each of the pair of second rollers 222 is configured to roll on a rolling surface formed on the movable rail 212 that extends vertically when the lifting member 25 moves vertically. In this embodiment, on each of the pair of movable rails 212, the rolling surface of the second roller 222 is located on the opposite side in the width direction W from the rolling surface of the first roller 221. Also in this embodiment, the lifting member 25 is divided into two members, each connected to the roller support member 23.

[0075] As shown in Figures 10 and 11, in this embodiment, the lifting drive device 26 comprises a pair of sprockets 261 and a hydraulic drive mechanism 8.

[0076] A pair of sprockets 261 are supported by support members 213 connected to a pair of movable rails 212. The pair of sprockets 261 are arranged side by side with a gap between them in the width direction W. A chain 27 is wrapped around each of the pair of sprockets 261. In this embodiment, one end of the pair of chains 27 is connected to a lifting member 25. The other end of the pair of chains 27 is connected to a rail fixing member 214 fixed to a pair of fixed rails 211.

[0077] The hydraulic drive mechanism 8 is configured to generate a driving force to raise and lower the fork 1 using hydraulic pressure. In this embodiment, the hydraulic drive mechanism 8 is positioned between the first obstacle sensor 91A and the travel drive device 5 in the width direction W. In the illustrated example, the hydraulic drive mechanism 8 is positioned between the first obstacle sensor 91A and one of the fixed rails 211 (the left fixed rail 211 in Figure 10) in the width direction W, and overlaps with the fixed rail 211 in a width direction view along the width direction W (see Figure 11).

[0078] In this embodiment, the hydraulic drive mechanism 8 includes a hydraulic cylinder 81, a tank 82, a pump 83, a motor 84, and a switching valve 85.

[0079] The hydraulic cylinder 81 is equipped with a cylinder rod 81a that is interlocked with the fork 1. In this embodiment, the cylinder rod 81a is supported so as to be able to move in and out in the vertical direction. The cylinder rod 81a is connected to a support member 213. As a result, as the cylinder rod 81a moves in and out, the pair of movable rails 212 move in the vertical direction via the support member 213, and the pair of sprockets 261 also move in the vertical direction. Consequently, the pair of forks 1 move up and down via the pair of chains 27, the lifting member 25, and the fork connecting member 24.

[0080] In this embodiment, a pair of hydraulic cylinders 81 are arranged on both sides in the width direction W, flanking the travel drive unit 5. Each of the pair of hydraulic cylinders 81 is positioned in front of the fixed rail 211 D1, and overlaps with the fixed rail 211 in a view along the front-rear direction D.

[0081] Tank 82 stores the oil supplied to and discharged from the hydraulic cylinder 81. Pump 83 generates the hydraulic pressure supplied to the hydraulic cylinder 81. Motor 84 is the drive source for pump 83. In this embodiment, pump 83 is located above motor 84, and tank 82 is located above pump 83. In this embodiment, tank 82, pump 83, and motor 84 are arranged to overlap each other when viewed in the vertical direction.

[0082] The switching valve 85 is configured to switch between a supply oil passage through which oil supplied to the hydraulic cylinder 81 flows and a discharge oil passage through which oil discharged from the hydraulic cylinder 81 flows.

[0083] As shown in Figure 12, in this embodiment, the cover 33 includes a first notch 33A and a second notch 33B.

[0084] The first notch 33A is located in the area of ​​the cover 33 through which the first detection surface S1 of the first obstacle sensor 91A passes. The first notch 33A is formed so that the first detection surface S1 of the first obstacle sensor 91A does not interfere with the cover 33. The second notch 33B is located in the area of ​​the cover 33 through which the first detection surface S1 of the second obstacle sensor 91B passes. The second notch 33B is formed so that the first detection surface S1 of the second obstacle sensor 91B does not interfere with the cover 33. In this embodiment, the first notch 33A and the second notch 33B are formed so that the first detection surfaces S1 of the first obstacle sensor 91A and the second obstacle sensor 91B extend to the front side D1, compared to when they are not formed in the cover 33. In the illustrated example, the first notch 33A and the second notch 33B are slits formed to extend inward in the width direction W and forward D1 from the first obstacle sensor 91A and the second obstacle sensor 91B, respectively. The first notch 33A and the second notch 33B are formed so that the first detection surface S1 of the first obstacle sensor 91A and the first detection surface S1 of the second obstacle sensor 91B overlap with each other at the front D1 relative to the transport vehicle 100.

[0085] As described above, in this embodiment, unlike the first embodiment, the counterweight 28, which is positioned outside the lifting rail 21 in the width direction W, does not move vertically along the lifting rail 21. Instead, the hydraulic drive mechanism 8 is positioned outside one of the fixed rails 211 (the left fixed rail 211 in Figure 10) in the width direction W. As shown in Figures 10 and 11, the hydraulic drive mechanism 8 is positioned above the first notch 33A. Therefore, the first detection surface S1 of the first obstacle sensor 91A does not interfere with the hydraulic drive mechanism 8.

[0086] 3. Other Embodiments (1) In the above embodiment, a configuration was described as 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. 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.

[0087] (2) 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.

[0088] (3) 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 is also possible.

[0089] (4) 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.

[0090] 4. Summary of this embodiment Below, we will describe the outline of the transport vehicle described above.

[0091] 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; a vehicle body supporting the lifting device, the plurality of wheels, and the drive unit; and a control device for controlling the lifting device and the drive unit, wherein the front-rear direction is defined as a specific direction along a horizontal plane, 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, and the direction along the horizontal plane and perpendicular to the front-rear direction is defined as the width direction; the forks are arranged to protrude from the lifting device toward the rear; the vehicle body comprises a main body supporting 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 first obstacle sensor and a second obstacle sensor for detecting obstacles present around the vehicle body, wherein the first obstacle sensor is arranged to protrude from the upper surface of the first leg, which is one of the pair of legs. The second obstacle sensor is positioned to protrude from the upper surface of the second leg, which is the other of the pair of legs, and the first and second obstacle sensors are positioned to overlap with the lifting device in a widthwise view along the width direction.

[0092] In this configuration, the first obstacle sensor and the second obstacle sensor are positioned so as to overlap with the lifting device in a widthwise view along the width direction. This allows the first and second obstacle sensors to be positioned away from the front of the tip of the fork. Therefore, it is easier to avoid the pallet supported by the fork coming into contact with at least one of the first and second obstacle sensors when the pallet is not properly supported by the fork. Furthermore, in this configuration, the first obstacle sensor is positioned so as to protrude from the upper surface of the first leg, and the second obstacle sensor is positioned so as to protrude from the upper surface of the second leg. This ensures that the detection areas of the first and second obstacle sensors are secured. Even in this configuration, as described above, since the first and second obstacle sensors are positioned so as to overlap with the lifting device in a widthwise view, it is possible to avoid the pallet coming into contact with at least one of the first and second obstacle sensors.

[0093] Here, the system further includes a third obstacle sensor for detecting obstacles present around the vehicle body, and it is preferable that the third obstacle sensor is positioned on the front side of the main body.

[0094] With this configuration, even if the detection areas of the first and second obstacle sensors interfere with the main body of the vehicle, the third obstacle sensor can appropriately detect obstacles located in front of the vehicle body.

[0095] Furthermore, it is preferable to further include a pair of pallet detection sensors, each positioned at the rear end of the pair of legs, which detect whether or not the pallet is located within the area between the pair of legs in the width direction.

[0096] This configuration allows for the detection of whether the positional relationship of the pallet being supported by the forks relative to the transport vehicle is appropriate. Therefore, it facilitates proper support of the pallet by the forks.

[0097] Furthermore, the vehicle body preferably comprises a cover that covers the main body, and the cover comprises a first notch located in the area through which the detection surface of the first obstacle sensor passes, and a second notch located in the area through which the detection surface of the second obstacle sensor passes.

[0098] With this configuration, the first notch makes it difficult for the detection surface of the first obstacle sensor to interfere with the cover, and the second notch makes it difficult for the detection surface of the second obstacle sensor to interfere with the cover. As a result, the detection surfaces of both the first and second obstacle sensors can be expanded.

[0099] In the above configuration, the lifting device is preferably equipped with a hydraulic drive mechanism that generates a driving force for raising and lowering the fork by hydraulic pressure, and the hydraulic drive mechanism is preferably located between the first obstacle sensor and the travel drive device in the width direction, and above the first notch.

[0100] This configuration allows for proper raising and lowering of the forks using a hydraulic drive mechanism while avoiding interference between the detection surface of the first obstacle sensor and the hydraulic drive mechanism.

[0101] The technology disclosed herein can be used in transport vehicles.

[0102] 100: Transport vehicle 1: Fork 2: Lifting device 3: Body 31: Main body 32: Legs 32A: First leg 32B: Second leg 33: Cover 33A: First notch 33B: Second notch 4: Wheel 41: Drive wheel 5: Driving device 8: Hydraulic drive mechanism 91A: First obstacle sensor 91B: Second obstacle sensor 92: Third obstacle sensor 94: First pallet detection sensor (pallet detection sensor) 10: Control device P: Pallet S1: First detection surface (detection surface) D: Front-rear direction D1: Front side D2: Rear side W: Width direction

Claims

Forks to support the pallet, A lifting device for raising and lowering the fork, Multiple wheels, including the drive wheels, A drive system that drives the aforementioned drive wheels, The vehicle body supports the lifting device, the plurality of wheels, and the driving device, A transport vehicle comprising a control device for controlling the lifting device and the travel drive device, 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 side, the other side of the front-rear direction is defined as the rear side, and a direction along the horizontal plane that is perpendicular to the front-rear direction is defined as the width direction. The fork is positioned 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 fork, so as to protrude from the main body toward the rear. The vehicle further comprises a first obstacle sensor and a second obstacle sensor for detecting obstacles present around the vehicle body, The first obstacle sensor is positioned to protrude from the upper surface of the first leg, which is one of the pair of legs. The second obstacle sensor is positioned to protrude from the upper surface of the second leg, which is the other leg of the pair. A transport vehicle in which the first obstacle sensor and the second obstacle sensor are arranged to overlap with the lifting device in a widthwise view along the width direction. 　 The vehicle further includes a third obstacle sensor for detecting obstacles present around the vehicle body, The transport vehicle according to claim 1, wherein the third obstacle sensor is positioned on the front side of the main body. 　 The transport vehicle according to claim 1 or 2, further comprising a pair of pallet detection sensors, each positioned at the rear end of a pair of legs, for detecting whether or not the pallet is located within the region between the pair of legs in the width direction. 　 The vehicle body further comprises a cover that covers the main body, The transport vehicle according to claim 1 or 2, wherein the cover comprises a first notch located in the region through which the detection surface of the first obstacle sensor passes, and a second notch located in the region through which the detection surface of the second obstacle sensor passes. 　 The lifting device includes a hydraulic drive mechanism that generates a driving force for raising and lowering the fork using hydraulic pressure. The transport vehicle according to claim 4, wherein the hydraulic drive mechanism is located between the first obstacle sensor and the travel drive device in the width direction, and above the first notch.

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