Transport vehicle

Abstract

To provide a technology that is able to prevent breakage of a transmission mechanism even when overload is applied to a dolly by a steering motor.SOLUTION: A dolly according to the present disclosure may include: a chassis; wheels supported on the chassis and grounded on the ground; holding members supported on the chassis so as to be each rotatable around a turning shaft, and each rotatably holding the wheel around a rotary shaft; a steering handle gripped by a user; an input sensor that detects an operation of the steering handle by the user; a steering motor that drives according to the operation by the user detected by the input sensor; and transmission mechanisms that each connect the steering motor and the holding member with each other and each rotate the holding member around the turning shaft according to the driving of the steering motor. The steering handle and the transmission mechanism may be mechanically separated. The transmission mechanism may include a torque limiter interposed between the steering motor and the holding member.SELECTED DRAWING: Figure 22

Description

[Technical field]

[0001] The technology disclosed herein relates to a transport vehicle. [Background technology]

[0002] Patent Document 1 discloses a vehicle. The vehicle includes a chassis, wheels supported by the chassis and in contact with the ground, a holding member supported by the chassis so as to be rotatable around a steering axis and holding the wheels rotatable around a rotation axis, a steering wheel held by a user, an input sensor that detects an operation of the steering wheel by the user, a steering motor that is driven in response to the operation by the user detected by the input sensor, and a transmission mechanism that connects the steering motor and the holding member and rotates the holding member around the steering axis in response to the drive of the steering motor. The steering wheel and the transmission mechanism are mechanically separated. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2006-44621 A Summary of the Invention [Problem to be solved by the invention]

[0004] When the vehicle described above is used as a transport vehicle for transporting luggage, if an overload is applied from the steering motor, the transmission mechanism may be damaged. This specification provides a technology that can prevent the transmission mechanism from being damaged in the transport vehicle even if an overload is applied from the steering motor. [Means for solving the problem]

[0005] In one or more embodiments, the transporter may include a chassis, wheels supported by the chassis and in contact with the ground, a holding member supported by the chassis so as to be rotatable about a steering axis and holding the wheels rotatably about a rotation axis, a steering wheel held by a user, an input sensor detecting an operation of the steering wheel by the user, a steering motor driven in response to the operation by the user detected by the input sensor, and a transmission mechanism connecting the steering motor and the holding member and rotating the holding member about the steering axis in response to the driving of the steering motor. The steering wheel and the transmission mechanism may be mechanically separated. The transmission mechanism may include a torque limiter interposed between the steering motor and the holding member.

[0006] According to the above configuration, the transmission mechanism is equipped with a torque limiter interposed between the steering motor and the retaining member, so that even if an overload is applied from the steering motor, damage to the transmission mechanism can be prevented. [Brief description of the drawings]

[0007] [Figure 1] FIG. 2 is a perspective view of a transporter 2 according to the embodiment, seen from above on the front right. [Diagram 2] FIG. 2 is a perspective view of a chassis unit 4 according to the embodiment, as viewed from below on the front right side. [Diagram 3] FIG. 2 is a perspective view of a chassis unit 4 according to the embodiment, as viewed from above and behind on the right. [Figure 4] 2 is a cross-sectional view of a chassis unit 4 according to the embodiment, taken along a cross section along the front-rear and up-down directions. FIG. [Diagram 5] 2 is a cross-sectional view of a chassis unit 4 according to the embodiment, taken along a cross section along the left-right direction and the up-down direction. FIG. [Figure 6] 2 is a perspective view of a handle unit 8 according to the embodiment, seen from above on the rear right side. FIG. [Figure 7] 1 is a perspective view of a lower portion of a handle unit 8 according to an embodiment, viewed from below on the front right. [Figure 8]1 is a perspective view of the support pipe 78, clamp member 80, fixing member 82, handle shaft 84, and rotation angle sensor 88 of the handle unit 8 according to the embodiment, as viewed from below and to the front right. [Figure 9] 1 is a perspective view of a movable cam member 90 of a handle unit 8 according to the embodiment, as viewed from above on the rear left side. [Figure 10] 1 is a perspective view of a fixed cam member 92 of a handle unit 8 according to the embodiment, as viewed from above on the front left. FIG. [Figure 11] 2 is a cross-sectional view showing a lower part of a handle unit 8 according to an embodiment of the present invention in a state in which a steering operation to the right has been performed, the cross-sectional view being taken along the front-rear and left-right directions. FIG. [Figure 12] 1 is a perspective view of the lower part of the handle unit 8 according to the embodiment, seen from below and on the front right, in a state in which a steering operation to the right has been performed in the handle unit 8 according to the embodiment. FIG. [Figure 13] 13 is a perspective view of a handle unit 108 according to a modified example, as viewed from above and rear right. FIG. [Figure 14] 1 is a perspective view of a support pipe 114, a clamp sleeve 116, an upper arm plate 120, and a handle sleeve 124 of a handle unit 108 according to a modified example, as viewed from above and rear right. [Figure 15] 13 is a cross-sectional view of a lower portion of a handle unit 108 according to a modified example, taken along a cross section along the front-rear and up-down directions. FIG. [Figure 16] This is an oblique view of the support pipe 114, clamp sleeve 116, upper arm plate 120, lower arm plate 122, handle sleeve 124, handle shaft 126, slide sleeve 134, and coil spring 136 of the handle unit 108 of a modified example, viewed from the front right below. [Figure 17] 13 is a cross-sectional view of a lower portion of a handle unit 108 according to a modified example, taken along a cross section along the left-right and up-down directions. FIG. [Figure 18]This is an oblique view of the support pipe 114, clamp sleeve 116, upper arm plate 120, lower arm plate 122, handle sleeve 124, handle shaft 126, and coil spring 136 of the handle unit 108 of a modified example, viewed from the front right below. [Figure 19] 13 is a cross-sectional view of a lower portion of a handle unit 108 according to a modified example, taken along cross sections along the left-right and up-down directions, in a state in which a steering operation to the right has been performed in the handle unit 108. FIG. [Figure 20] 1 is a perspective view of a steering unit 10 and a front wheel unit 12 according to an embodiment, viewed from above on the front left. [Figure 21] 1 is a perspective view of a steering unit 10 according to an embodiment, seen from above on the front left. [Figure 22] 1 is a cross-sectional view of a steering unit 10 according to an embodiment, taken along a cross section along the front-rear and left-right directions. [Diagram 23] 1 is an exploded oblique view of the spindle 178, cam wheel 180, movable gear 182, and coil spring 184 of the steering unit 10 according to the embodiment, viewed from the rear left below. [Figure 24] 1 is a cross-sectional view of a steering unit 10 according to an embodiment, taken along a cross section along the front-rear and up-down directions. [Diagram 25] 1 is a perspective view of a right front wheel unit 12a according to an embodiment, as viewed from above on the front left. [Figure 26] 2 is a cross-sectional view of a right front wheel unit 12a according to the embodiment, taken along a cross section along the left-right and up-down directions. FIG. [Figure 27] 1 is a front view of a steering unit 10 and a front wheel unit 12 according to an embodiment in a non-sinking state. [Figure 28] FIG. 2 is a front view of the steering unit 10 and the front wheel unit 12 according to the embodiment in a maximum sinking state. [Figure 29]FIG. 1 is a top view of the steering plate 170, the right tie rod 172, the left tie rod 174, the right front wheel unit 12a, and the left front wheel unit 12b in the steering unit 10 and front wheel unit 12 of the embodiment when steering to the right in a non-sinking state. [Diagram 30] FIG. 1 is a top view of the steering plate 170, the right tie rod 172, the left tie rod 174, the right front wheel unit 12a, and the left front wheel unit 12b in the steering unit 10 and front wheel unit 12 of the embodiment when steering to the right in the maximum sinking state. [Diagram 31] 1 is a perspective view of a rear wheel unit 14 according to an embodiment, as viewed from above and to the rear right. [Diagram 32] 1 is a perspective view of a right rear wheel unit 14a according to an embodiment, as viewed from above on the rear left side. FIG. [Diagram 33] FIG. 2 is a rear view of the lower part of the transporter 2 according to the embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] Representative and non-limiting examples of the present invention will now be described in detail with reference to the drawings. This detailed description is intended simply to provide those skilled in the art with details for implementing preferred examples of the present invention, and is not intended to limit the scope of the present invention. Additionally, additional features and inventions disclosed below may be used separately or in conjunction with other features and inventions to provide further improved transport vehicles, methods of making and using the same.

[0009] Furthermore, the combinations of features and steps disclosed in the following detailed description are not essential to the practice of the invention in its broadest sense, but are specifically described only to illustrate representative embodiments of the invention. Furthermore, the various features of the representative embodiments described above and below, and the various features of those described in the independent and dependent claims, do not have to be combined in the exact embodiments described herein, or in the exact order listed, to provide additional and useful embodiments of the invention.

[0010] All features described in the specification and / or claims are intended to be disclosed individually and independently of one another as limitations to the original disclosure and claimed particulars, apart from any configuration of features described in the examples and / or claims. Furthermore, all numerical ranges and group or aggregate descriptions are intended to disclose their intermediate configurations as limitations to the original disclosure and claimed particulars.

[0011] In one or more embodiments, the transporter may include a chassis, wheels supported by the chassis and in contact with the ground, a holding member supported by the chassis so as to be rotatable about a steering axis and holding the wheels rotatably about a rotation axis, a steering wheel held by a user, an input sensor detecting an operation of the steering wheel by the user, a steering motor driven in response to the operation by the user detected by the input sensor, and a transmission mechanism connecting the steering motor and the holding member and rotating the holding member about the steering axis in response to the driving of the steering motor. The steering wheel and the transmission mechanism may be mechanically separated. The transmission mechanism may include a torque limiter interposed between the steering motor and the holding member.

[0012] According to the above configuration, the transmission mechanism is equipped with a torque limiter interposed between the steering motor and the retaining member, so that even if an overload is applied from the steering motor, damage to the transmission mechanism can be prevented.

[0013] In one or more embodiments, the transmission mechanism may include a steering angle sensor disposed between the steering motor and the holding member for detecting a steering angle in the transmission mechanism, and the torque limiter may be disposed between the steering motor and the steering angle sensor.

[0014] According to the above configuration, the torque limiter is disposed between the steering motor and the steering angle sensor, so that even when the torque limiter is activated and the transmission of power in the transmission mechanism is cut off, it is possible to prevent the steering angle detected using the steering angle sensor from deviating from the actual steering angle in the transmission mechanism.

[0015] In one or more embodiments, the transmission mechanism may further include a steering shaft that is rotatable with respect to the chassis and that rotates in response to driving of the steering motor, a link member fixed to the steering shaft, and a tie rod having one end rotatably attached to the link member and the other end rotatably attached to the holding member. The steering angle sensor may be disposed between the steering motor and the steering shaft.

[0016] According to the above configuration, the torque limiter and the steering angle sensor can be disposed at positions away from the wheels and the holding member.

[0017] In one or more embodiments, the transmission mechanism may further include an intermediate shaft that is rotatable with respect to the chassis and is interposed between the steering motor and the steering shaft. The intermediate shaft may have a first gear portion. The steering shaft may have a second gear portion that meshes with the first gear portion. The steering angle sensor may be attached to the intermediate shaft.

[0018] According to the above configuration, the steering angle can be detected by the steering angle sensor with higher accuracy.

[0019] In one or more embodiments, the transmission mechanism may further include a spindle that is rotatable relative to the chassis and rotates in response to driving of the steering motor. The spindle may have a cylindrical worm portion. The relay shaft may further include a worm wheel portion that meshes with the cylindrical worm portion.

[0020] According to the above configuration, although rotation is transmitted from the spindle to the intermediate shaft, rotation is not transmitted from the intermediate shaft to the spindle. Therefore, even if the retaining member receives torque around the steering axis due to, for example, an external force, the torque can be prevented from being transmitted to the steering motor via the transmission mechanism.

[0021] In one or more embodiments, the steering motor may include a motor shaft that rotates in response to driving of the steering motor. The motor shaft may have a third gear portion. The torque limiter may include a cam wheel fixed to the spindle, a movable gear that is movable relative to the spindle along the axial direction of the spindle and meshes with the third gear portion, and a coil spring that biases the movable gear toward the cam wheel relative to the spindle. The cam wheel may have a cam groove. The movable gear may have a cam protrusion that corresponds to the cam groove.

[0022] According to the above configuration, a torque limiter can be realized with a simple configuration.

[0023] (Example) The transporter 2 shown in FIG. 1 includes a chassis unit 4, a loading platform unit 6, a handle unit 8, a steering unit 10, a front wheel unit 12, and a rear wheel unit 14. The transporter 2 transports luggage loaded on the loading platform unit 6. The transporter 2 includes a receiver (not shown) mounted on the chassis unit 4. The transporter 2 can operate in a manual mode in which the transporter 2 moves forward or backward while a user standing behind the handle unit 8 holds the handle unit 8. Alternatively, the transporter 2 can operate in a follow-up mode in which the transporter moves by following a beacon (not shown) carried by a user standing in front of the chassis unit 4, or in an automatic mode in which the transporter 2 moves according to instructions from a remote control (not shown) carried by the user. In this case, the transporter 2 receives radio waves from the beacon or remote control by the receiver. Alternatively, the transporter 2 can operate in a parking mode in which the rear wheel unit 14 is locked and the transporter 2 remains stopped on the spot.

[0024] (Chassis Unit 4) As shown in Figs. 2 and 3, the chassis unit 4 includes a base plate 20, a front support member 22, a rear support member 24, a lower right frame 26, a lower left frame 28, an upper right frame 30, an upper left frame 32, a battery box 34, and a controller case 36. The base plate 20 is an aluminum member having a generally rectangular flat plate shape with its longitudinal direction along the front-rear direction and its short side direction along the left-right direction. As shown in Fig. 2, the front support member 22 is a steel member and is fixed to the underside of the base plate 20 at the front of the base plate 20. The rear support member 24 is a steel member and is fixed to the underside of the base plate 20 at the rear of the base plate 20. The lower right frame 26 and the lower left frame 28 are both steel members and extend in the front-rear direction below the base plate 20. The front portion of the lower-right frame 26 and the front portion of the lower-left frame 28 are each fixed to the front support member 22. The rear portion of the lower-right frame 26 and the rear portion of the lower-left frame 28 are each fixed to the rear support member 24. As shown in Fig. 3, the upper-right frame 30 and the upper-left frame 32 are both aluminum members, and extend in the front-rear direction above the base plate 20. The upper-right frame 30 and the upper-left frame 32 are each fixed to the upper surface of the base plate 20.

[0025] As shown in FIG. 3, the battery box 34 is a resin member and is disposed near the rear of the base plate 20 and below the base plate 20. The battery box 34 is fixed to the rear support member 24. As shown in FIG. 4, a battery attachment section 40 to which a battery pack 38 can be attached and detached is provided inside the battery box 34. The battery pack 38 includes secondary battery cells, such as lithium-ion battery cells. The transporter 2 operates by power supplied from the battery pack 38 attached to the battery attachment section 40. An openable battery cover 42 is provided at the rear of the battery box 34. The battery pack 38 can be attached and detached to and from the battery attachment section 40 by sliding the battery pack 38 in the front-rear direction relative to the battery attachment section 40 with the battery cover 42 open.

[0026] 2, the controller case 36 is a resin member, and is disposed below the base plate 20 and near the center of the base plate 20. The controller case 36 is fixed to the lower right frame 26 and the lower left frame 28 in a state in which it is placed on the upper surfaces of the lower right frame 26 and the lower left frame 28. As shown in FIGS. 4 and 5, the controller case 36 holds one main control circuit board 44, two drive control circuit boards 46, 48, and four electric brake circuit boards 50, 52, 54, 56.

[0027] As shown in Fig. 4, the main control circuit board 44 is housed inside a circuit board case 44a. The circuit board case 44a is housed inside the rear of the controller case 36. The circuit board case 44a is arranged so that the main control circuit board 44 is aligned in the up-down and left-right directions. The main control circuit board 44 is equipped with a circuit for controlling the operation of the transporter 2.

[0028] As shown in FIG. 5, the drive control circuit boards 46, 48 are housed in circuit board cases 46a, 48a, respectively. As shown in FIG. 4, the circuit board cases 46a, 48a are housed in the front lower part inside the controller case 36. The circuit board cases 46a, 48a are arranged so that the drive control circuit boards 46, 48 are aligned in the front-rear direction and the left-right direction. The drive control circuit boards 46, 48 are electrically connected to the main control circuit board 44. The operation of the drive control circuit boards 46, 48 is controlled by the main control circuit board 44. The drive control circuit boards 46, 48 are equipped with circuits for controlling the operation of the steering motor 176, the right front wheel motor 232, the left front wheel motor 242, the right rear wheel motor, the left rear wheel motor, the right rear wheel electromagnetic brake, and the left rear wheel electromagnetic brake, which will be described later.

[0029] As shown in Fig. 5, the electric brake circuit boards 50, 52, 54, 56 are attached to heat dissipation cases 50a, 52a, 54a, 56a, respectively. The heat dissipation cases 50a, 52a, 54a, 56a include circuit board housings 50b, 52b, 54b, 56b that house the electric brake circuit boards 50, 52, 54, 56, respectively, heat dissipation fins 50c, 52c, 54c, 56c, and cooling fans 50d, 52d, 54d, 56d. The heat dissipation cases 50a, 52a are housed in the upper front part inside the controller case 36. The heat dissipation cases 50a, 52a are arranged so that the electric brake circuit boards 50, 52 are aligned in the front-rear and left-right directions, and the cooling fans 50d, 52d face upward. The heat dissipation cases 54a, 56a are fixed to a heat dissipation plate 58 fixed to the controller case 36 at the lower front of the exterior of the controller case 36. The heat dissipation cases 54a, 56a are arranged so that the electric brake circuit boards 54, 56 are aligned in the front-rear and left-right directions and the cooling fans 54d, 56d face downward. The electric brake circuit boards 50, 54 and the cooling fans 50d, 54d are electrically connected to the drive control circuit board 46. The operation of the electric brake circuit boards 50, 54 and the cooling fans 50d, 54d is controlled by the drive control circuit board 46. The electric brake circuit boards 52, 56 and the cooling fans 52d, 56d are electrically connected to the drive control circuit board 48. The operation of the electric brake circuit boards 52, 56 and the cooling fans 52d, 56d is controlled by the drive control circuit board 48. The electric brake circuit boards 50, 52, 54, 56 are equipped with circuits for applying electric brakes to the right front wheel motor 232, the left front wheel motor 242, the right rear wheel motor, and the left rear wheel motor, which will be described later.

[0030] (Cargo unit 6) As shown in FIG. 1, the loading platform unit 6 includes a main frame 60, a right guard 62, a left guard 64, and a front guard 66. The main frame 60, the right guard 62, the left guard 64, and the front guard 66 are all made of steel round pipes. The main frame 60 is disposed above the base plate 20 of the chassis unit 4 along the front-rear and left-right directions. The main frame 60 is fixed to the upper right frame 30 and the upper left frame 32 of the chassis unit 4 while being placed on the upper surfaces of the upper right frame 30 and the upper left frame 32. On the upper surface of the main frame 60, luggage to be transported by the transport vehicle 2 is placed. The right guard 62 is attached to the right end of the main frame 60 so as to protrude upward from the upper surface of the main frame 60. The right guard 62 is disposed along the front-rear and up-down directions. The left guard 64 is attached to the left end of the main frame 60 so as to protrude upward from the upper surface of the main frame 60. The left guard 64 is disposed so as to extend along the front-rear and up-down directions. The front guard 66 is attached to the front end of the main frame 60 so as to protrude above the upper surface of the main frame 60. The front guard 66 is disposed so as to extend along the left-right and up-down directions.

[0031] (Handle unit 8) 6, the handle unit 8 includes a switch box 70, a right handle 72, a left handle 74, a handle arm 76, a support pipe 78, a clamp member 80, a fixed member 82, a handle shaft 84, a base member 86, a rotation angle sensor 88, a movable cam member 90, a fixed cam member 92, and a coil spring 94. In the following description, the right handle 72, the left handle 74, the handle arm 76, and the support pipe 78 are collectively referred to as the steering handle 73.

[0032] The switch box 70 is provided with a main power switch 96, a mode change switch 98, a trigger switch 100, a travel direction change switch 102, a speed change switch 104, and a warning horn switch 106. The main power switch 96 can switch the main power of the transport vehicle 2 on / off. The mode change switch 98 can switch the operation mode of the transport vehicle 2 among a manual mode, an automatic mode, and a parking mode. The trigger switch 100 can switch the forward and reverse of the transport vehicle 2 on / off and adjust the travel speed of the transport vehicle 2 in the manual mode. The travel direction change switch 102 can switch the travel direction of the transport vehicle 2 in the manual mode. The speed change switch 104 can switch the travel speed of the transport vehicle 2 in the manual mode. The warning horn switch 106 can sound a warning horn using a buzzer (not shown) built into the switch box 70. The main power switch 96, the mode change switch 98, the trigger switch 100, the travel direction change switch 102, the speed change switch 104, the horn switch 106, and the buzzer are each electrically connected to the main control circuit board 44 (see FIG. 4).

[0033] The right handle 72 includes a support portion 72a extending in the vertical direction and a handle portion 72b bent to the right from the upper end of the support portion 72a. The lower end of the support portion 72a is fixed to a handle arm 76. A right grip 72c is provided at the right end of the handle portion 72b. The switch box 70 is fixed to the handle portion 72b to the left of the right grip 72c. The left handle 74 includes a support portion 74a extending in the vertical direction and a handle portion 74b bent to the left from the upper end of the support portion 74a. The lower end of the support portion 74a is fixed to the handle arm 76. A left grip 74c is provided at the left end of the handle portion 74b. The upper end of a support pipe 78 is fixed to the handle arm 76. The support pipe 78 extends in the vertical direction. The clamp member 80 includes clamp pieces 80a and 80b that clamp the support pipe 78 from both the left and right sides. A fastening portion 80c is formed at the rear end of the clamp pieces 80a and 80b to be fastened by a fastener (not shown). When the fastener of the fastening portion 80c is tightened, the clamp pieces 80a and 80b are pressed strongly against the outer surface of the support pipe 78, and the support pipe 78 is fixed to the clamp member 80. When the fastener of the fastening portion 80c is loosened, the clamp pieces 80a and 80b are not pressed against the outer surface of the support pipe 78, and the support pipe 78 becomes movable in the vertical direction relative to the clamp member 80 and can rotate around the vertical direction. With the fastener of the fastening portion 80c loosened, the support pipe 78 is adjusted to a desired position and angle relative to the clamp member 80, and then the fastener of the fastening portion 80c is tightened, thereby fixing the position and angle of the support pipe 78 relative to the clamp member 80.

[0034] As shown in FIG. 7, the front part of the clamp member 80 is fixed to a fixed member 82. The upper end of a handle shaft 84 is fixed to the fixed member 82. The lower end of the handle shaft 84 is rotatably supported by a base member 86. The base member 86 is fixed to the upper surface of the base plate 20 of the chassis unit 4. A rotation angle sensor 88 is fixed to the lower part of the base member 86. The rotation angle sensor 88 is connected to the lower end of the handle shaft 84. The rotation angle sensor 88 detects the rotation angle of the handle shaft 84 relative to the base member 86. The rotation angle sensor 88 may be, for example, a potentiometer that detects a change in electrical resistance value according to a change in the rotation angle. Alternatively, the rotation angle sensor 88 may be a magnetic rotary sensor including a Hall element whose position is fixed relative to the base member 86 and a permanent magnet whose position is fixed relative to the handle shaft 84. The rotation angle sensor 88 is electrically connected to the main control circuit board 44 (see FIG. 4).

[0035] 8, a guide protrusion 84a is provided on the handle shaft 84. The guide protrusion 84a protrudes radially outward from the outer circumferential surface of the handle shaft 84 and extends along the axial direction of the handle shaft 84.

[0036] As shown in FIG. 9, the movable cam member 90 has a substantially cylindrical shape. Cam protrusions 90a and 90b extending downward are formed on the lower portion of the movable cam member 90. The cam protrusions 90a and 90b are provided with first cam faces 90c and 90d and second cam faces 90e and 90f, respectively. When the movable cam member 90 is viewed from above, the first cam faces 90c and 90d are inclined so as to face from the bottom to the top in the clockwise direction. When the movable cam member 90 is viewed from above, the second cam faces 90e and 90f are inclined so as to face from the bottom to the top in the counterclockwise direction. A guide groove 90g is formed on the inner peripheral surface of the movable cam member 90. The guide groove 90g has a width corresponding to the guide protrusion 84a (see FIG. 8) and extends in a direction along the central axis of the movable cam member 90. When the movable cam member 90 is attached to the handle shaft 84, the guide protrusion 84a engages with the guide groove 90g so as to be slidable in the vertical direction. Therefore, the movable cam member 90 is held on the handle shaft 84 so as to be movable in the vertical direction. A spring receiving portion 90h that supports a coil spring 94 is formed on the upper part of the movable cam member 90. As shown in FIG. 7, the coil spring 94 biases the movable cam member 90 downward against the fixed member 82.

[0037] As shown in FIG. 10, the fixed cam member 92 includes a cylindrical portion 92a having a substantially cylindrical shape and a flange portion 92b extending radially outward from the lower end of the cylindrical portion 92a. The fixed cam member 92 is fixed to the base member 86 (see FIG. 7) by fastening the flange portion 92b to the upper surface of the base member 86 with a fastener (not shown). Cam recesses 92c and 92d corresponding to the cam protrusions 90a and 90b of the movable cam member 90 are formed on the upper portion of the cylindrical portion 92a. The cam recesses 92c and 92d are provided with first cam surfaces 92e and 92f and second cam surfaces 92g and 92h, respectively. The first cam surfaces 92e and 92f correspond to the first cam surfaces 90c and 90d of the movable cam member 90, respectively. The second cam surfaces 92g and 92h correspond to the second cam surfaces 90e and 90f of the movable cam member 90, respectively. In addition, stopper portions 92i and 92j are provided on the inner peripheral surface of the cylindrical portion 92a. As shown in Fig. 11, when the handle shaft 84 rotates relative to the fixed cam member 92, the stopper portions 92i and 92j come into contact with the guide protrusions 84a of the handle shaft 84, thereby restricting the rotation range of the handle shaft 84.

[0038] In the handle unit 8 shown in Fig. 6, when the user rotates the steering wheel 73 clockwise (or counterclockwise) as viewed from above, the handle shaft 84 rotates clockwise (or counterclockwise). At this time, as shown in Fig. 12, the movable cam member 90 rotates integrally with the handle shaft 84, so that the first cam faces 90c, 90d (or the second cam faces 90e, 90f) of the movable cam member 90 slide against the first cam faces 92e, 92f (or the second cam faces 92g, 92h) of the fixed cam member 92, and the movable cam member 90 moves upward against the biasing force of the coil spring 94 while rotating relatively to the fixed cam member 92. At this time, the torque due to the reaction force that the movable cam member 90 receives from the fixed cam member 92 acts on the user who rotates the steering wheel 73.

[0039] In the handle unit 8, the fixed member 82, the handle shaft 84, the coil spring 94, the movable cam member 90, the fixed cam member 92, and the rotation angle sensor 88 are arranged on the same axis. By adopting such a configuration, it is possible to reduce the dimensions in the front-rear and left-right directions.

[0040] (Handle unit 108) The transporter 2 may include a handle unit 108 shown in Figs. 13-19 instead of the handle unit 8. As shown in Fig. 13, the handle unit 108 includes a switch box 110, a handle bar 112, a support pipe 114, a clamp sleeve 116, a clamp member 118, an upper arm plate 120, a lower arm plate 122, a handle sleeve 124, a handle shaft 126 (see Fig. 15), a cover member 128, a base member 130, a rotation angle sensor 132, a slide sleeve 134 (see Fig. 15), and a coil spring 136 (see Fig. 15). In the following description, the handle bar 112 and the support pipe 114 are collectively referred to as a steering handle 113.

[0041] The handlebar 112 extends in the left-right direction. A right grip 112a is provided at the right end of the handlebar 112. The switch box 110 is fixed to the handlebar 112 near the right grip 112a. The switch box 110 has a configuration substantially similar to that of the switch box 70 of the handle unit 8. A left grip 112b is provided at the left end of the handlebar 112. The upper end of a support pipe 114 is fixed to the center of the handlebar 112. The support pipe 114 extends in the up-down direction. The support pipe 114 passes through a clamp sleeve 116. As shown in FIG. 14, a clamp portion 116a is provided at the upper end of the clamp sleeve 116. A slit 116b is formed in the clamp portion 116a and extends downward from the upper end of the clamp portion 116a. As shown in FIG. 13, the clamp member 118 includes clamp pieces 118a and 118b that clamp the clamp portion 116a of the clamp sleeve 116 from both the left and right sides. A bolt 118c and a nut 118d are attached to the rear ends of the clamp pieces 118a and 118b. The bolt 118c penetrates the rear parts of the clamp pieces 118a and 118b. The nut 118d is screwed onto the tip of the bolt 118c. The nut 118d is provided with a pin 118e. By raising the pin 118e and rotating the pin 118e relative to the bolt 118c, the nut 118d can be rotated relative to the bolt 118c. When the nut 118d is tightened to the bolt 118c, the clamp pieces 118a and 118b are strongly pressed against the outer surface of the clamp portion 116a of the clamp sleeve 116, and the inner surface of the clamp portion 116a is strongly pressed against the outer surface of the support pipe 114. This fixes the support pipe 114 to the clamp sleeve 116. When the nut 118d is loosened relative to the bolt 118c, the clamp pieces 118a, 118b are no longer pressed against the outer surface of the clamp sleeve 116, and therefore the inner surface of the clamp portion 116a is no longer pressed against the outer surface of the support pipe 114. This allows the support pipe 114 to move up and down relative to the clamp sleeve 116 and to rotate around the up and down direction.With nut 118d loosened from bolt 118c, support pipe 114 can be adjusted to the desired position and angle relative to clamp sleeve 116, and then nut 118d can be tightened onto bolt 118c to fix the position and angle of support pipe 114 relative to clamp sleeve 116.

[0042] As shown in FIG. 15, the upper arm plate 120 connects the clamp sleeve 116 and the handle sleeve 124. The lower arm plate 122 connects the clamp sleeve 116 and the handle sleeve 124 below the upper arm plate 120. The handle sleeve 124 is fixed to the upper end of the handle shaft 126. The handle shaft 126 penetrates a cover member 128 and a base member 130. The cover member 128 rotatably supports the handle shaft 126 at the upper end of the cover member 128. The base member 130 rotatably supports the handle shaft 126 at the lower end of the base member 130. The cover member 128 is fixed to the base member 130. The base member 130 is fixed to the upper surface of the base plate 20 (see FIG. 3) of the chassis unit 4. A rotation angle sensor 132 is fixed to the lower part of the base member 130. The rotation angle sensor 132 is connected to the lower end of the handle shaft 126. The rotation angle sensor 132 detects the rotation angle of the handle shaft 126 relative to the base member 130. The rotation angle sensor 132 may be, for example, a potentiometer that detects a change in electrical resistance value according to a change in the rotation angle. Alternatively, the rotation angle sensor 132 may be a magnetic rotary sensor including a Hall element whose position is fixed relative to the base member 130 and a permanent magnet whose position is fixed relative to the handle shaft 126. The rotation angle sensor 132 is electrically connected to the main control circuit board 44 (see FIG. 4).

[0043] The slide sleeve 134 is attached to the handle shaft 126 so as to cover the outer circumferential surface of the handle shaft 126 inside the cover member 128 and the base member 130. As shown in FIG. 16, the slide sleeve 134 is provided with guide grooves 134a, 134b, a spring receiving portion 134c, and ball holding holes 134d, 134e (see FIG. 17). The guide grooves 134a, 134b are recessed radially inward from the outer circumferential surface of the slide sleeve 134 and extend in the vertical direction. Guide pins 150a, 150b extending in the vertical direction are slidably engaged with the guide grooves 134a, 134b. As shown in FIG. 15, the lower portions of the guide pins 150a, 150b are fixed to the base member 130. Therefore, the slide sleeve 134 is held so as to be movable in the vertical direction relative to the base member 130. The spring receiving portion 134c supports the lower end of the coil spring 136. Coil spring 136 is disposed inside cover member 128 and base member 130, and biases slide sleeve 134 downward relative to cover member 128. In the following description, the portion of the upper part of cover member 128 that supports the upper end of coil spring 136 is also referred to as fixed member 128a.

[0044] As shown in Fig. 17, the balls 152a and 152b enter the ball retaining holes 134d and 134e from the inside. The inner diameters of the ball retaining holes 134d and 134e are slightly larger than the outer diameters of the balls 152a and 152b. Since the outsides of the ball retaining holes 134d and 134e are covered by the base member 130, the ball retaining holes 134d and 134e rotatably retain the balls 152a and 152b. The balls 152a and 152b also enter the ball grooves 126a and 126b formed on the outer circumferential surface of the handle shaft 126 from the outside. As shown in Fig. 18, the ball grooves 126a, 126b respectively include first ball grooves 126c, 126d which are inclined from bottom to top as they move counterclockwise when the handle shaft 126 is viewed from above, and second ball grooves 126e, 126f which are inclined from bottom to top as they move clockwise. The balls 152a, 152b can roll along the first ball grooves 126c, 126d and the second ball grooves 126e, 126f, respectively. In the following description, the slide sleeve 134 and the balls 152a, 152b are also collectively referred to as the movable cam member 135 (see Fig. 17).

[0045] In the handle unit 108 shown in Fig. 13, when the user rotates the steering wheel 113 clockwise (or counterclockwise) as viewed from above, the handle shaft 126 rotates clockwise (or counterclockwise). At this time, as shown in Fig. 19, the balls 152a, 152b held in the ball holding holes 134d, 134e roll in the first ball grooves 126c, 126d (or the second ball grooves 126e, 126f) of the handle shaft 126, and the slide sleeve 134 moves upward against the biasing force of the coil spring 136. At this time, a torque due to a reaction force that the handle shaft 126 receives from the slide sleeve 134 via the balls 152a, 152b acts on the user who rotates the steering wheel 113.

[0046] In the handle unit 108, the fixed member 128a, the handle shaft 126, the coil spring 136, the movable cam member 135, and the rotation angle sensor 132 are arranged on the same axis. This configuration can reduce the dimensions in the front-rear and left-right directions. In addition, in the handle unit 108, most of the handle shaft 126, the coil spring 136, and the periphery of the movable cam member 135 are covered by the cover member 128 and the base member 130. This configuration can prevent mud or water from adhering to the handle shaft 126, the coil spring 136, and the movable cam member 135, causing malfunction.

[0047] (Steering unit 10) As shown in Figure 20, the steering unit 10 is attached to a front support member 22 below the front part of the base plate 20 (see Figure 2) of the chassis unit 4. The steering unit 10 is connected to the front wheel unit 12 and steers the front wheel unit 12.

[0048] As shown in Fig. 21, the steering unit 10 includes a motor housing 160, a motor support member 162, a gear housing 164, a steering angle sensor 166, a steering shaft 168, a steering plate 170, a right tie rod 172, and a left tie rod 174. The motor housing 160 is fixed to the motor support member 162. The motor support member 162 is fixed to the gear housing 164. The gear housing 164 is fixed to the front support member 22 (see Fig. 20) of the chassis unit 4.

[0049] As shown in FIG. 22, a steering motor 176 is housed inside the motor housing 160. The steering motor 176 is, for example, an inner rotor type brushless DC motor. The steering motor 176 is electrically connected to the drive control circuit board 46 (see FIG. 5). The drive control circuit board 46 controls the operation of the steering motor 176. The steering motor 176 has a motor shaft 176a extending in the front-rear direction. The motor shaft 176a is rotatably held by the motor housing 160 near its rear end, and is rotatably held by the motor support member 162 at its front portion. The front portion of the motor shaft 176a penetrates the motor support member 162 and enters the inside of the gear housing 164. A gear portion 176b is formed near the front end of the motor shaft 176a.

[0050] The gear housing 164 accommodates a spindle 178, a cam wheel 180, a movable gear 182, a coil spring 184, a cylindrical worm 186, a worm wheel 188, and an intermediate shaft 190. The spindle 178 is disposed along the front-rear direction. The spindle 178 is rotatably held by the gear housing 164 near its front end and at its rear. The spindle 178 is also rotatably held by the motor support member 162 near its rear end.

[0051] The cam wheel 180 is fixed near the rear end of the spindle 178. As shown in FIG. 23, a cam groove 180a is formed on the front surface of the cam wheel 180. The movable gear 182 is attached to the spindle 178 forward of the cam wheel 180. The movable gear 182 is held by the spindle 178 so as to be movable in the front-rear direction relative to the spindle 178 and rotatable around the front-rear direction. A gear portion 182a that meshes with a gear portion 176b (see FIG. 22) of the motor shaft 176a is formed on the outer circumferential surface of the movable gear 182. A recess 182b into which the cam wheel 180 fits is formed on the rear portion of the movable gear 182. A cam protrusion 182c that corresponds to the cam groove 180a of the cam wheel 180 is formed in the recess 182b. The coil spring 184 is attached to the spindle 178 forward of the movable gear 182. The coil spring 184 is held by a spring receiving portion 178a provided on the spindle 178. The coil spring 184 biases the movable gear 182 rearward relative to the spindle 178.

[0052] When the motor shaft 176a (see FIG. 22) rotates, the movable gear 182 also rotates. When the cam protrusion 182c of the movable gear 182 is engaged with the cam groove 180a of the cam wheel 180, the cam wheel 180 rotates with the rotation of the movable gear 182, and the spindle 178 also rotates. When the torque acting between the movable gear 182 and the cam wheel 180 is small, the engagement between the cam protrusion 182c and the cam groove 180a is maintained by the biasing force of the coil spring 184, and the transmission of rotation from the motor shaft 176a to the spindle 178 is maintained. On the other hand, when the torque acting between the movable gear 182 and the cam wheel 180 is large, the movable gear 182 moves forward against the biasing force of the coil spring 184, the engagement between the cam protrusion 182c and the cam groove 180a is released, and the transmission of rotation from the motor shaft 176a to the spindle 178 is interrupted. That is, the cam wheel 180 , the movable gear 182 , and the coil spring 184 form a torque limiter 181 .

[0053] As shown in Fig. 22, the cylindrical worm 186 is fixed to the front part of the spindle 178. The worm wheel 188 is arranged to mesh with the cylindrical worm 186. As shown in Fig. 24, the worm wheel 188 is fixed to the upper part of the intermediate shaft 190. The intermediate shaft 190 is arranged to extend in the up-down direction. The intermediate shaft 190 is rotatably held by the gear housing 164 near the upper end and at the center. A gear portion 190a is formed near the lower end of the intermediate shaft 190.

[0054] A steering angle sensor 166 is fixed to the upper part of the gear housing 164. The steering angle sensor 166 is connected to the upper end of the relay shaft 190. The steering angle sensor 166 detects the rotation angle of the relay shaft 190 with respect to the gear housing 164. The steering angle sensor 166 may be, for example, a potentiometer that detects a change in electrical resistance value according to a change in the rotation angle. Alternatively, the steering angle sensor 166 may be a magnetic rotary sensor including a Hall element whose position is fixed with respect to the gear housing 164 and a permanent magnet whose position is fixed with respect to the relay shaft 190. The steering angle sensor 166 is electrically connected to the main control circuit board 44 (see FIG. 4).

[0055] The steering shaft 168 is rotatably held by the gear housing 164 near the upper end and at the upper part. The steering shaft 168 is arranged along the up-down direction. A gear part 168a that meshes with a gear part 190a of the intermediate shaft 190 is formed on the upper part of the steering shaft 168. The lower end of the steering shaft 168 is fixed near the front end of the steering plate 170. As shown in FIG. 21, the steering plate 170 has a long and thin flat plate shape with a longitudinal direction in the front-rear direction and a transverse direction in the left-right direction. The rear end of the right tie rod 172 and the rear end of the left tie rod 174 are respectively connected near the rear end of the steering plate 170. The rear end of the right tie rod 172 is connected to the steering plate 170 so as to be rotatable around two axes perpendicular to the longitudinal direction of the right tie rod 172. The rear end of the left tie rod 174 is connected to the steering plate 170 so as to be rotatable about two axes perpendicular to the longitudinal direction of the left tie rod 174 .

[0056] As shown in FIG. 22, when the spindle 178 rotates due to the rotation of the motor shaft 176a, the rotation of the spindle 178 is transmitted to the relay shaft 190 via the cylindrical worm 186 and the worm wheel 188. As shown in FIG. 24, when the relay shaft 190 rotates, the steering shaft 168 rotates accordingly, and the rear end of the steering plate 170 rotates in the left-right direction. This rotation of the steering plate 170 moves the right tie rod 172 and the left tie rod 174 shown in FIG. 21, and the front wheel unit 12 is steered. In the following description, the steering shaft 168, the steering plate 170, the right tie rod 172, the left tie rod 174, the spindle 178, the torque limiter 181, the cylindrical worm 186, the worm wheel 188, and the relay shaft 190 are also collectively referred to as the transmission mechanism 169.

[0057] In the manual mode, the main control circuit board 44 (see FIG. 4) calculates the steering angle to be realized in the steering unit 10 based on the detection signals from the rotation angle sensors 88, 132 of the handle units 8, 108 (see FIGS. 6 and 13). Then, the main control circuit board 44 calculates the rotation angle to be realized by the steering motor 176 based on the steering angle to be realized in the steering unit 10, and instructs the drive control circuit board 48 to drive the steering motor 176. As a result, a steering angle corresponding to the user's operation of the handle units 8, 108 is realized in the steering unit 10.

[0058] (Front wheel unit 12) As shown in Fig. 20, the front wheel unit 12 is attached to a front support member 22 below the front part of the base plate 20 (see Fig. 2) of the chassis unit 4. The front wheel unit 12 includes a right front wheel unit 12a and a left front wheel unit 12b. The right front wheel unit 12a includes a right front wheel 192, a right gear housing 194, a right motor housing 196, a right kingpin 198, a right sleeve 200, an upper right arm 202, a lower right arm 204, a right shock absorber 206, a right steering plate 208, and a right actual steering angle sensor 210. The left front wheel unit 12b includes a left front wheel 212, a left gear housing 214, a left motor housing 216, a left kingpin 218 (see FIG. 27), a left sleeve 220, a left upper arm 222, a left lower arm 224, a left buffer member 226, a left steering plate 228, and a left actual steering angle sensor 230. In the following description, the right gear housing 194, the right kingpin 198, the right sleeve 200, and the right steering plate 208 are collectively referred to as the right retaining member 195, and the left gear housing 214, the left kingpin 218, the left sleeve 220, and the left steering plate 228 are collectively referred to as the left retaining member 215. In addition, the right side retaining member 195, the upper right arm 202, the lower right arm 204, the right side buffer member 206, the left side retaining member 215, the upper left arm 222, the lower left arm 224, the left side buffer member 226, and the steering unit 10 are collectively referred to as the suspension mechanism 11.

[0059] As shown in FIG. 25, the right gear housing 194 is disposed on the left side of the right front wheel 192. The right motor housing 196 is fixed to the left part of the right gear housing 194. As shown in FIG. 26, the right motor housing 196 accommodates a right front wheel motor 232 inside. The right front wheel motor 232 is, for example, an inner rotor type brushless DC motor. The right front wheel motor 232 is electrically connected to a drive control circuit board 46 (see FIG. 5). The drive control circuit board 46 controls the operation of the right front wheel motor 232. The right front wheel motor 232 includes a right front wheel motor shaft 232a extending in the left-right direction and a right front wheel motor rotation speed sensor 232b that detects the rotation speed of the right front wheel motor shaft 232a. The right front wheel motor shaft 232a is rotatably held by the right motor housing 196 near the left end and rotatably held by the right gear housing 194 near the right end. The right front wheel 192 is equipped with a right front wheel axle 192a extending to the left. The right front wheel axle 192a is rotatably held in a right gear housing 194 near the left end. A planetary gear mechanism 234 is accommodated inside the right gear housing 194. The planetary gear mechanism 234 reduces the rotation of the right front wheel motor shaft 232a and transmits it to the right front wheel axle 192a. When the right front wheel motor 232 is driven, the rotation of the right front wheel motor shaft 232a is transmitted to the right front wheel axle 192a via the planetary gear mechanism 234, causing the right front wheel 192 to rotate.

[0060] The right kingpin 198 is fixed to the upper part of the right gear housing 194. The right kingpin 198 extends in the up-down direction. The upper part of the right kingpin 198 is inserted into the right sleeve 200. The right kingpin 198 is rotatably held by the right sleeve 200 near the upper end and the lower end of the right sleeve 200. As shown in FIG. 25, the right end of the upper right arm 202 is connected to the upper part of the right sleeve 200 so as to be rotatable around a rotation axis along the front-rear direction. The right end of the right lower arm 204 is connected to the lower part of the right sleeve 200 so as to be rotatable around a rotation axis along the front-rear direction. As shown in FIG. 20, the left end of the upper right arm 202 is connected to the upper right connecting part 22a of the front support member 22 so as to be rotatable around a rotation axis along the front-rear direction. The left end of the right lower arm 204 is rotatably connected to the right lower connecting portion 22b of the front support member 22 about a rotation axis along the front-rear direction. Therefore, the right sleeve 200 is supported by the front support member 22 so as to be movable within the movable range of the upper right arm 202 and the lower right arm 204.

[0061] The right-side shock absorbing member 206 includes a damper 206a and a coil spring 206b. An upper end of the right-side shock absorbing member 206 is connected to the front surface of the front support member 22 so as to be rotatable about a rotation axis along the front-rear direction. A lower end of the right-side shock absorbing member 206 is connected to the front surface of the right lower arm 204 so as to be rotatable about a rotation axis along the front-rear direction. Therefore, when the right front wheel 192 moves in the up-down direction relative to the front support member 22, the damping force of the damper 206a and the elastic restoring force of the coil spring 206b suppress the transmission of impact and vibration from the right front wheel 192 to the chassis unit 4.

[0062] 25, the right steering plate 208 is fixed near the lower end of the right kingpin 198. The front end of the right tie rod 172 is connected to the left front end of the right steering plate 208 so as to be rotatable around two axes perpendicular to the longitudinal direction of the right tie rod 172. When the right front wheel unit 12a is viewed from above, the right tie rod 172 crosses the upper right arm 202 and the lower right arm 204. When the front wheel unit 12 is steered to the right (or left), the rear end of the steering plate 170 (see FIG. 21) moves to the right (or left), causing the right steering plate 208, the right kingpin 198, the right gear housing 194, the right motor housing 196, and the right front wheel 192 to rotate clockwise (or counterclockwise) relative to the right sleeve 200, when viewed from above, with the axial direction of the right kingpin 198 as the steering axis.

[0063] The right actual steering angle sensor 210 is fixed to an upper part of the right sleeve 200. The right actual steering angle sensor 210 is connected to an upper end of the right kingpin 198. The right actual steering angle sensor 210 detects a rotation angle of the right kingpin 198 with respect to the right sleeve 200. The right actual steering angle sensor 210 may be, for example, a potentiometer that detects a change in electrical resistance value according to a change in the rotation angle. Alternatively, the right actual steering angle sensor 210 may be a magnetic rotary sensor including a Hall element whose position is fixed with respect to the right sleeve 200 and a permanent magnet whose position is fixed with respect to the right kingpin 198. The right actual steering angle sensor 210 is electrically connected to the main control circuit board 44 (see FIG. 4).

[0064] As shown in Fig. 20, the left front wheel unit 12b has a configuration symmetrical to the right front wheel unit 12a. The left front wheel unit 12b will be described below with reference to Figs. 25 and 26 which show the right front wheel unit 12a.

[0065] As shown in FIG. 25, the left gear housing 214 is disposed on the right side of the left front wheel 212. The left motor housing 216 is fixed to the right part of the left gear housing 214. As shown in FIG. 26, the left front wheel motor 242 is accommodated inside the left motor housing 216. The left front wheel motor 242 is, for example, an inner rotor type brushless DC motor. The left front wheel motor 242 is electrically connected to a drive control circuit board 48 (see FIG. 5). The drive control circuit board 48 controls the operation of the left front wheel motor 242. The left front wheel motor 242 includes a left front wheel motor shaft 242a extending in the left-right direction and a left front wheel motor rotation speed sensor 242b that detects the rotation speed of the left front wheel motor shaft 242a. The left front wheel motor shaft 242a is rotatably held by the left motor housing 216 near the right end and rotatably held by the left gear housing 214 near the left end. The left front wheel 212 is equipped with a left axle 212a extending to the right. The left axle 212a is rotatably held by a left gear housing 214 near its right end. A planetary gear mechanism 244 is housed inside the left gear housing 214. The planetary gear mechanism 244 reduces the rotation of the left front wheel motor shaft 242a and transmits it to the left axle 212a. When the left front wheel motor 242 is driven, the rotation of the left front wheel motor shaft 242a is transmitted to the left axle 212a via the planetary gear mechanism 244, causing the left front wheel 212 to rotate.

[0066] The left kingpin 218 is fixed to the upper part of the left gear housing 214. The left kingpin 218 extends in the up-down direction. The upper part of the left kingpin 218 is inserted inside the left sleeve 220. The left kingpin 218 is rotatably held by the left sleeve 220 near the upper end and the lower end of the left sleeve 220. As shown in FIG. 25, the left end of the left upper arm 222 is connected to the upper part of the left sleeve 220 so as to be rotatable around a rotation axis along the front-rear direction. The left end of the left lower arm 224 is connected to the lower part of the left sleeve 220 so as to be rotatable around a rotation axis along the front-rear direction. As shown in FIG. 20, the right end of the left upper arm 222 is connected to the left upper connecting part 22c of the front support member 22 so as to be rotatable around a rotation axis along the front-rear direction. The right end of the left lower arm 224 is rotatably connected to the left lower connecting portion 22d of the front support member 22 around a rotation axis along the front-rear direction. Therefore, the left sleeve 220 is supported by the front support member 22 so as to be movable within the movable range of the left upper arm 222 and the left lower arm 224.

[0067] The left side buffer member 226 includes a damper 226a and a coil spring 226b. An upper end of the left side buffer member 226 is connected to the front surface of the front support member 22 so as to be rotatable about a rotation axis along the front-rear direction. A lower end of the left side buffer member 226 is connected to the front surface of the left lower arm 224 so as to be rotatable about a rotation axis along the front-rear direction. Therefore, when the left front wheel 212 moves in the up-down direction relative to the front support member 22, the damping force of the damper 226a and the elastic restoring force of the coil spring 226b suppress the transmission of impact and vibration from the left front wheel 212 to the chassis unit 4.

[0068] 25, the left steering plate 228 is fixed near the lower end of the left kingpin 218. The front end of the left tie rod 174 is connected to the right front end of the left steering plate 228 so as to be rotatable around two axes perpendicular to the longitudinal direction of the left tie rod 174. When the left front wheel unit 12b is viewed from above, the left tie rod 174 crosses the left upper arm 222 and the left lower arm 224. When the front wheel unit 12 is steered to the right (or left), the rear end of the steering plate 170 (see FIG. 21) moves to the right (or left), causing the left steering plate 228, the left kingpin 218, the left gear housing 214, the left motor housing 216, and the left front wheel 212 to rotate clockwise (or counterclockwise) relative to the left sleeve 220, when viewed from above, with the axial direction of the left kingpin 218 as the steering axis.

[0069] The left actual steering angle sensor 230 is fixed to an upper part of the left sleeve 220. The left actual steering angle sensor 230 is connected to an upper end of the left kingpin 218. The left actual steering angle sensor 230 detects a rotation angle of the left kingpin 218 with respect to the left sleeve 220. The left actual steering angle sensor 230 may be, for example, a potentiometer that detects a change in an electrical resistance value according to a change in the rotation angle. Alternatively, the left actual steering angle sensor 230 may be a magnetic rotary sensor including a Hall element whose position is fixed with respect to the left sleeve 220 and a permanent magnet whose position is fixed with respect to the left kingpin 218. The left actual steering angle sensor 230 is electrically connected to the main control circuit board 44 (see FIG. 4).

[0070] As shown in Fig. 27, when the chassis unit 4 is not sunken relative to the right front wheel 192 or the left front wheel 212 (hereinafter also referred to as a non-sunk state), the steering plate 170 is located above the right steering plate 208 or the left steering plate 228 by a first predetermined height H1. Such a non-sunk state is realized, for example, when no baggage is placed on the bed unit 6 and the transporter 2 is stopped. In contrast, as shown in Fig. 28, when the chassis unit 4 is maximally sunken relative to the right front wheel 192 or the left front wheel 212 (hereinafter also referred to as a maximum sunken state), the steering plate 170 is located below the right steering plate 208 or the left steering plate 228 by a second predetermined height H2. Such a state of maximum subsidence is realized, for example, when the maximum load allowed by the right-side buffer member 206 and the left-side buffer member 226 is applied to the right-side buffer member 206 and the left-side buffer member 226 during use of the transport vehicle 2. In the transport vehicle 2 of this embodiment, the first predetermined height H1 and the second predetermined height H2 are substantially equal. In this case, as shown in Fig. 29, the lengths R1 and L1 of the right-side tie rod 172 and the left-side tie rod 174 projected onto a plane perpendicular to the vertical direction in a state of no subsidence are substantially equal to the lengths R2 and L2 of the right-side tie rod 172 and the left-side tie rod 174 projected onto a plane perpendicular to the vertical direction in a state of maximum subsidence as shown in Fig. 30.

[0071] The lengths R and L of the right tie rod 172 and the left tie rod 174 projected on a plane perpendicular to the vertical direction increase as the chassis unit 4 sinks from a non-sunk state, and reach a maximum when the steering plate 170 reaches the same height as the right steering plate 208 and the left steering plate 228. After that, as the chassis unit 4 sinks further toward the maximum sinking state, the steering plate 170 drops below the right steering plate 208 and the left steering plate 228, and the lengths R and L of the right tie rod 172 and the left tie rod 174 projected on a plane perpendicular to the vertical direction decrease. In the transport vehicle 2 of this embodiment, the lengths R1 and L1 in the non-sunk state and the lengths R2 and L2 in the maximum sinking state are approximately equal, so that the fluctuation range of the lengths R and L of the right tie rod 172 and the left tie rod 174 projected on a plane perpendicular to the vertical direction can be reduced.

[0072] (Rear wheel unit 14) As shown in FIG. 31, the rear wheel unit 14 is attached to the rear support member 24 below the rear of the base plate 20 (see FIG. 2) of the chassis unit 4. The rear wheel unit 14 includes a right rear wheel unit 14a and a left rear wheel unit 14b. The right rear wheel unit 14a includes a right rear wheel 252, a right gear housing 254, a right motor housing 256, a right brake housing 258, a right clutch lever 260, a right rear wheel rotation speed sensor 262 (see FIG. 32), and a right buffer member 264. The left rear wheel unit 14b includes a left rear wheel 272, a left gear housing 274, a left motor housing 276, a left brake housing 278, a left clutch lever 280, a left rear wheel rotation speed sensor 282, and a left buffer member 284.

[0073] As shown in FIG. 32, the right gear housing 254 is disposed on the left side of the right rear wheel 252 and rotatably holds a right rear wheel axle (not shown) of the right rear wheel 252. The right gear housing 254 extends forward and upward from the right rear wheel axle. The right motor housing 256 is fixed to the left part of the front upper part of the right gear housing 254. The right brake housing 258 is fixed to the left part of the right motor housing 256. A right rear wheel motor (not shown) is accommodated inside the right motor housing 256. The right rear wheel motor is, for example, an inner rotor type brushless DC motor. The right rear wheel motor is electrically connected to the drive control circuit board 46 (see FIG. 5). The drive control circuit board 46 controls the operation of the right rear wheel motor. The right rear wheel motor includes a right rear wheel motor shaft (not shown) extending in the left-right direction and a right rear wheel motor rotation speed sensor (not shown) that detects the rotation speed of the right rear wheel motor shaft. The right brake housing 258 houses a right rear wheel electromagnetic brake (not shown). The right rear wheel electromagnetic brake is connected to the right rear wheel motor shaft. The right rear wheel electromagnetic brake switches between a state in which rotation of the right rear wheel motor shaft is permitted and a state in which rotation is prohibited. The right rear wheel electromagnetic brake is electrically connected to the drive control circuit board 46 (see FIG. 5). The drive control circuit board 46 controls the operation of the right rear wheel electromagnetic brake. In the parking mode, the right rear wheel electromagnetic brake is maintained in a state in which rotation of the right rear wheel motor shaft is prohibited.

[0074] A spur gear mechanism (not shown) and a clutch mechanism (not shown) are housed inside the right gear housing 254. The spur gear mechanism reduces the speed of rotation of the right rear wheel motor shaft and transmits it to the right rear wheel axle. When the right rear wheel motor is driven, the rotation of the right rear wheel motor shaft is transmitted to the right rear wheel axle via the spur gear mechanism, causing the right rear wheel 252 to rotate. The clutch mechanism switches between a state in which the transmission of rotation from the right rear wheel motor shaft to the right rear wheel axle is permitted and a state in which the transmission is interrupted in response to the operation of the right clutch lever 260. Therefore, when the right rear wheel electromagnetic brake prohibits the rotation of the right rear wheel motor shaft, the clutch mechanism can be switched to a state in which the transmission of rotation from the right rear wheel motor shaft to the right rear wheel axle is interrupted, thereby preventing the right rear wheel 252 from locking. The right rear wheel speed sensor 262 is fixed to the left part of the lower rear part of the right gear housing 254. The right rear wheel rotation speed sensor 262 is connected to the left end of the right rear axle. The right rear wheel rotation speed sensor 262 detects the rotation speed of the right rear axle relative to the right gear housing 254. The right rear wheel rotation speed sensor 262 is electrically connected to the main control circuit board 44 (see FIG. 4).

[0075] A connecting portion 254a is provided near the front upper end of the right gear housing 254. The connecting portion 254a is connected to the rear support member 24 so as to be rotatable around a rotation axis along the left-right direction. The right buffer member 264 includes a damper 264a and a coil spring 264b. The upper end of the right buffer member 264 is connected to the rear support member 24 so as to be rotatable around a rotation axis along the left-right direction, rearward and above the connecting portion 254a. The lower end of the right buffer member 264 is connected to the rear upper surface of the right gear housing 254 so as to be rotatable around a rotation axis along the left-right direction. Therefore, when the right rear wheel 252 moves in the up-down direction relative to the rear support member 24, the damping force of the damper 264a and the elastic restoring force of the coil spring 264b suppress the transmission of impact and vibration from the right rear wheel 252 to the chassis unit 4.

[0076] As shown in Fig. 31, the left rear wheel unit 14b has a configuration symmetrical to the right rear wheel unit 14a. The left rear wheel unit 14b will be described below with reference to Fig. 32 which illustrates the right rear wheel unit 14a.

[0077] As shown in FIG. 32, the left gear housing 274 is disposed on the right side of the left rear wheel 272 and rotatably holds a left rear wheel axle (not shown) of the left rear wheel 272. The left gear housing 274 extends forward and upward from the left rear wheel axle. The left motor housing 276 is fixed to the right part of the front upper part of the left gear housing 274. The left brake housing 278 is fixed to the right part of the left motor housing 276. A left rear wheel motor (not shown) is accommodated inside the left motor housing 276. The left rear wheel motor is, for example, an inner rotor type brushless DC motor. The left rear wheel motor is electrically connected to the drive control circuit board 48 (see FIG. 5). The drive control circuit board 48 controls the operation of the left rear wheel motor. The left rear wheel motor includes a left rear wheel motor shaft (not shown) extending in the left-right direction and a left rear wheel motor rotation speed sensor (not shown) that detects the rotation speed of the left rear wheel motor shaft. The left brake housing 278 houses a left rear wheel electromagnetic brake (not shown). The left rear wheel electromagnetic brake is connected to the left rear wheel motor shaft. The left rear wheel electromagnetic brake switches between a state in which rotation of the left rear wheel motor shaft is permitted and a state in which rotation is prohibited. The left rear wheel electromagnetic brake is electrically connected to the drive control circuit board 48 (see FIG. 5). The drive control circuit board 48 controls the operation of the left rear wheel electromagnetic brake. In the parking mode, the left rear wheel electromagnetic brake is maintained in a state in which rotation of the left rear wheel motor shaft is prohibited.

[0078] A spur gear mechanism (not shown) and a clutch mechanism (not shown) are housed inside the left gear housing 274. The spur gear mechanism reduces the speed of rotation of the left rear wheel motor shaft and transmits it to the left rear wheel axle. When the left rear wheel motor is driven, the rotation of the left rear wheel motor shaft is transmitted to the left rear wheel axle via the spur gear mechanism, causing the left rear wheel 272 to rotate. The clutch mechanism switches between a state in which the transmission of rotation from the left rear wheel motor shaft to the left rear wheel axle is permitted and a state in which the transmission is interrupted in response to the operation of the left clutch lever 280. Therefore, when the left rear wheel electromagnetic brake prohibits the rotation of the left rear wheel motor shaft, the clutch mechanism can be switched to a state in which the transmission of rotation from the left rear wheel motor shaft to the left rear wheel axle is interrupted, thereby preventing the left rear wheel 272 from locking. The left rear wheel rotation speed sensor 282 is fixed to the right part of the lower rear part of the left gear housing 274. The left rear wheel rotation speed sensor 282 is connected to the right end of the left rear axle. The left rear wheel rotation speed sensor 282 detects the rotation speed of the left rear axle relative to the left gear housing 274. The left rear wheel rotation speed sensor 282 is electrically connected to the main control circuit board 44 (see FIG. 4).

[0079] A connecting portion 274a is provided near the front upper end of the left gear housing 274. The connecting portion 274a is connected to the rear support member 24 so as to be rotatable around a rotation axis along the left-right direction. The left buffer member 284 includes a damper 284a and a coil spring 284b. The upper end of the left buffer member 284 is connected to the rear support member 24 rearward and above the connecting portion 274a so as to be rotatable around a rotation axis along the left-right direction. The lower end of the left buffer member 284 is connected to the rear upper surface of the left gear housing 274 so as to be rotatable around a rotation axis along the left-right direction. Therefore, when the left rear wheel 272 moves in the vertical direction relative to the rear support member 24, the damping force of the damper 284a and the elastic restoring force of the coil spring 284b suppress the transmission of impact and vibration from the left rear wheel 272 to the chassis unit 4.

[0080] The main control circuit board 44 (see Figure 4) can calculate the actual traveling trajectory of the transporter 2 based on the steering angle obtained from the detection signal of the steering angle sensor 166 of the steering unit 10, the respective rotation speeds of the right front wheel motor 232 and the left front wheel motor 242 obtained from the respective detection signals of the right front wheel motor rotation speed sensor 232b and the left front wheel motor rotation speed sensor 242b of the front wheel unit 12, and the respective rotation speeds of the right rear wheel motor and the left rear wheel motor obtained from the respective detection signals of the right rear wheel motor rotation speed sensor and left rear wheel motor rotation speed sensor of the rear wheel unit 14.

[0081] As shown in FIG. 33, when the transporter 2 is viewed from the rear, a lower space 290 is formed below the center of the chassis unit 4, extending upward from the ground surface GS. As shown in FIG. 27 and FIG. 28, the lower space 290 includes a midpoint CP1 of a straight line CL1 connecting the center of the right front wheel 192 and the center of the left front wheel 212. The lower space 290 has a width CW1 between the right front wheel 192 and the left front wheel 212. The width CW1 is 1 / 3 or more of the distance W1 between the left side surface of the right front wheel 192 and the right side surface of the left front wheel 212. Also, as shown in FIG. 33, the lower space 290 includes a midpoint CP2 of a straight line CL2 connecting the center of the right rear wheel 252 and the center of the left rear wheel 272. The lower space 290 has a width CW2 between the right rear wheel 252 and the left rear wheel 272. The width CW2 is equal to or greater than 1 / 3 of the distance W2 between the left side surface of the right rear wheel 252 and the right side surface of the left rear wheel 272. With this configuration, even if an obstacle exists on the ground surface GS, it is possible to prevent the steering unit 10, the front wheel unit 12, the rear wheel unit 14, etc. from colliding with the obstacle.

[0082] (Modification) In the above embodiment, the right front wheel motor 232, the left front wheel motor 242, the right rear wheel motor, and the left rear wheel motor may be in-wheel motors (not shown) incorporated in the right front wheel 192, the left front wheel 212, the right rear wheel 252, and the left rear wheel 272.

[0083] In the above embodiments, the steering motor 176, the right front wheel motor 232, the left front wheel motor 242, the right rear wheel motor, and the left rear wheel motor may be an outer rotor type brushless DC motor, a brushed DC motor, an AC motor, or another type of motor.

[0084] 6 may include a movable cam member 90, a fixed cam member 92, a coil spring 94, and a cover member (not shown) that covers a part of the handle shaft 84. In this case, the fixed member 82 may constitute a part of the cover member.

[0085] In the above-described embodiments, the handle units 8, 108 shown in Figures 6 and 13 may include other types of elastic members instead of the coil springs 94, 136. The handle units 8, 108 may also include a damper (not shown) that applies a damping force to the rotation of the handle shafts 84, 126.

[0086] As described above, in one or more embodiments, the transporter 2 includes the chassis unit 4 (an example of a chassis), the right front wheel 192 and the left front wheel 212 (an example of wheels) that are supported by the chassis unit 4 and come into contact with the ground, the right side holding member 195 and the left side holding member 215 (an example of a holding member) that are supported by the chassis unit 4 so as to be rotatable about a steering axis and that hold the right front wheel 192 and the left front wheel 212 so as to be rotatable about a rotation axis, and the steering handles 73, 113 that are held by the user. The steering wheel 73, 113 is provided with a rotation angle sensor 88, 132 (an example of an input sensor) that detects the user's operation on the steering wheel 73, 113, a steering motor 176 that is driven in response to the user's operation detected by the rotation angle sensor 88, 132, and a transmission mechanism 169 that connects the steering motor 176 with a right holding member 195 and a left holding member 215 and rotates the right holding member 195 and the left holding member 215 around the steering axis in response to the driving of the steering motor 176. The steering wheel 73, 113 and the transmission mechanism 169 are mechanically separated. The transmission mechanism 169 is provided with a torque limiter 181 that is interposed between the steering motor 176 and the right holding member 195 and the left holding member 215.

[0087] According to the above configuration, the transmission mechanism 169 is provided with the torque limiter 181 interposed between the steering motor 176 and the right-side holding member 195 and between the steering motor 176 and the left-side holding member 215, so that even if an overload is applied from the steering motor 176, damage to the transmission mechanism 169 can be suppressed.

[0088] In one or more embodiments, the transmission mechanism 169 is disposed between the steering motor 176 and the right retaining member 195 and the left retaining member 215, and includes a steering angle sensor 166 for detecting the steering angle in the transmission mechanism 169. The torque limiter 181 is disposed between the steering motor 176 and the steering angle sensor 166.

[0089] According to the above configuration, the torque limiter 181 is disposed between the steering motor 176 and the steering angle sensor 166. Therefore, even if the torque limiter 181 is activated and the transmission of power in the transmission mechanism 169 is cut off, it is possible to prevent the steering angle detected using the steering angle sensor 166 from deviating from the actual steering angle in the transmission mechanism 169.

[0090] In one or more embodiments, the transmission mechanism 169 further includes a steering shaft 168 that is rotatable relative to the chassis unit 4 and rotates in response to driving of the steering motor 176, a steering plate 170 (an example of a link member) fixed to the steering shaft 168, and a right tie rod 172 and a left tie rod 174 (an example of a tie rod) each having one end rotatably attached to the steering plate 170 and the other end rotatably attached to the right holding member 195 and the left holding member 215. The steering angle sensor 166 is disposed between the steering motor 176 and the steering shaft 168.

[0091] According to the above configuration, the torque limiter 181 and the steering angle sensor 166 can be disposed at positions away from the right front wheel 192 , the left front wheel 212 , the right side holding member 195 , and the left side holding member 215 .

[0092] In one or more embodiments, the transmission mechanism 169 further includes an intermediate shaft 190 that is rotatable relative to the chassis unit 4 and is interposed between the steering motor 176 and the steering shaft 168. The intermediate shaft 190 has a gear portion 190a (an example of a first gear portion). The steering shaft 168 has a gear portion 168a (an example of a second gear portion) that meshes with the gear portion 190a. The steering angle sensor 166 is attached to the intermediate shaft 190.

[0093] According to the above configuration, the steering angle sensor 166 can detect the steering angle with higher accuracy.

[0094] In one or more embodiments, the transmission mechanism 169 further includes a spindle 178 that is rotatable relative to the chassis unit 4 and rotates in response to driving of the steering motor 176. The spindle 178 includes a cylindrical worm 186 (an example of a cylindrical worm portion). The relay shaft 190 further includes a worm wheel 188 (an example of a worm wheel portion) that meshes with the cylindrical worm 186.

[0095] According to the above configuration, although rotation is transmitted from the spindle 178 to the relay shaft 190, rotation is not transmitted from the relay shaft 190 to the spindle 178. Therefore, even if the right side retaining member 195 and the left side retaining member 215 receive torque around the steering axis due to, for example, an external force, the torque can be prevented from being transmitted to the steering motor 176 via the transmission mechanism 169.

[0096] In one or more embodiments, the steering motor 176 includes a motor shaft 176a that rotates in response to driving of the steering motor 176. The motor shaft 176a includes a gear portion 176b (third gear portion). The torque limiter 181 includes a cam wheel 180 fixed to the spindle 178, a movable gear 182 that is movable relative to the spindle 178 along the axial direction of the spindle 178 and meshes with the gear portion 176b, and a coil spring 184 that biases the movable gear 182 toward the cam wheel 180 relative to the spindle 178. The cam wheel 180 includes a cam groove 180a. The movable gear 182 includes a cam protrusion 182c that corresponds to the cam groove 180a.

[0097] According to the above configuration, the torque limiter 181 can be realized with a simple structure. [Explanation of symbols]

[0098] 2: Transport vehicle 4: Chassis unit 6: Cargo unit 8: Handle unit 10: Steering unit 11: Suspension mechanism 12: Front wheel unit 12a: Right front wheel unit 12b: Left front wheel unit 14: Rear wheel unit 14a: Right rear wheel unit 14b: Left rear wheel unit 20: Base plate 22: Front support member 22a: Upper right side connection part 22b: Lower right side connection part 22c: Upper left connection part 22d: Lower left connection part 24: Rear support member 26: Lower right frame 28: Lower left frame 30: Top right frame 32: Upper left frame 34: Battery box 36: Controller case 38: Battery pack 40: Battery mounting section 42: Battery cover 44: Main control circuit board 44a: Circuit board case 46: Drive control circuit board 46a: Circuit board case 48: Drive control circuit board 48a: Circuit board case 50: Electric brake circuit board 50a: Heat dissipation case 50b: Circuit board housing 50c: Heat sink fin 50d: Cooling fan 52: Electric brake circuit board 52a: Heat dissipation case 52b: Circuit board housing 52c: Heat dissipation fin 52d: Cooling fan 54: Electric brake circuit board 54a: Heat dissipation case 54b: Circuit board housing 54c: Heat sink fin 54d: Cooling fan 56: Electric brake circuit board 56a: Heat dissipation case 56b: Circuit board housing 56c: Heat sink fin 56d: Cooling fan 58: Heat dissipation plate 60: Mainframe 62: Right guard 64: Left guard 66: Front guard 70: Switch box 72: Right-hand drive 72a: Support part 72b: Handle section 72c: Right grip 73: Steering wheel 74: Left-hand drive 74a: Support part 74b: Handle part 74c: Left grip 76: Handle arm 78: Support pipe 80: Clamping member 80a: Clamp piece 80b: Clamp piece 80c: Fastening part 82: Fixing member 84: Handle shaft 84a: Guide protrusion 86: Base material 88: Rotation angle sensor 90: Movable cam member 90a: Cam protrusion 90b: Cam protrusion 90c: First cam surface 90d: First cam surface 90e: Second cam surface 90f: Second cam surface 90g: Guide groove 90h: Spring support 92: Fixed cam member 92a: Cylindrical part 92b: Flange part 92c: Cam recess 92d: Cam recess 92e: First cam surface 92f: First cam surface 92g: Second cam surface 92h: Second cam surface 92i: Stopper part 92j: Stopper part 94: Coil spring 96: Main power switch 98: Mode switch 100: Trigger switch 102: Direction change switch 104: Speed ​​change switch 106: Horn switch 108: Handle unit 110: Switch box 112:Handlebar 112a: Right grip 112b: Left grip 113: Steering wheel 114: Support pipe 116: Clamp sleeve 116a: Clamp section 116b: Slit 118: Clamping member 118a: Clamp piece 118b: Clamp piece 118c:Bolt 118d : Nut 118e: Pin 120: Upper arm plate 122: Lower arm plate 124: Handle sleeve 126: Handle shaft 126a: Ball groove 126b: Ball groove 126c: First ball groove 126d: First ball groove 126e: Second ball groove 126f: 2nd ball groove 128: Cover member 128a: Fixing member 130: Base material 132: Rotation angle sensor 134: Slide sleeve 134a: Guide groove 134b: Guide groove 134c: Spring support 134d: Ball retaining hole 134e: Ball retaining hole 135: Movable cam member 136: Coil spring 150a: Guide pin 150b: Guide pin 152a: Ball 152b: Ball 160: Motor housing 162: Motor support member 164: Gear housing 166: Steering angle sensor 168: Steering shaft 168a: Gear section 169: Transmission mechanism 170: Steering plate 172: Right tie rod 174: Left tie rod 176: Steering motor 176a: Motor shaft 176b: Gear section 178: Spindle 178a: Spring support 180: Cam wheel 180a: Cam groove 181: Torque limiter 182: Movable gear 182a: Gear section 182b: Recess 182c: Cam protrusion 184: Coil spring 186: Cylindrical worm 188: Worm wheel 190: Intermediate shaft 190a: Gear section 192: Right front wheel 192a: Right front axle 194: Right side gear housing 195: Right side holding member 196: Right motor housing 198: Right kingpin 200: Right sleeve 202: Upper right arm 204: Lower right arm 206: Right side buffer member 206a: Damper 206b: Coil spring 208: Right side steering plate 210: Right side actual steering angle sensor 212:Left front wheel 212a: Left axle 214: Left gear housing 215: Left side retaining member 216: Left motor housing 218: Left kingpin 220: Left sleeve 222: Upper left arm 224: Lower left arm 226: Left side shock absorber 226a: Damper 226b : Coil spring 228: Left steering plate 230: Left actual steering angle sensor 232: Right front wheel motor 232a: Right front wheel motor shaft 232b: Right front wheel motor speed sensor 234: Planetary gear mechanism 242: Left front wheel motor 242a: Left front wheel motor shaft 242b: Left front wheel motor speed sensor 244: Planetary gear mechanism 252: Right rear wheel 254: Right side gear housing 254a: Connection part 256: Right motor housing 258: Right brake housing 260: Right clutch lever 262:Right rear wheel speed sensor 264: Right side buffer member 264a: Damper 264b : Coil spring 272: Left rear wheel 274: Left gear housing 274a: Connection part 276: Left motor housing 278: Left brake housing 280: Left clutch lever 282: Left rear wheel speed sensor 284: Left side shock absorber 284a: Damper 284b : Coil spring 290: Downward space

Claims

1. A transport vehicle, The chassis and A wheel supported by the chassis and adapted to contact the ground; a holding member supported on the chassis so as to be rotatable around a steering axis and configured to hold the wheel so as to be rotatable around a rotation axis; A steering wheel held by a user; an input sensor for detecting an operation of the steering wheel by the user; a steering motor that is driven in response to the operation by the user detected by the input sensor; a transmission mechanism that connects the steering motor and the holding member and rotates the holding member around the steering axis in response to driving of the steering motor, The steering wheel and the transmission mechanism are mechanically separated, the transmission mechanism includes a torque limiter interposed between the steering motor and the holding member, the transmission mechanism further includes a steering angle sensor disposed between the steering motor and the holding member for detecting a steering angle in the transmission mechanism, The torque limiter is disposed between the steering motor and the steering angle sensor.

2. The transmission mechanism is a steering shaft that is rotatable relative to the chassis and that rotates in response to driving of the steering motor; A link member fixed to the steering shaft; a tie rod having one end pivotally attached to the link member and the other end pivotally attached to the holding member; 2. The vehicle of claim 1, wherein the steering angle sensor is disposed between the steering motor and the steering shaft.

3. the transmission mechanism further includes an intermediate shaft that is rotatable with respect to the chassis and is interposed between the steering motor and the steering shaft, The intermediate shaft has a first gear portion, The steering shaft has a second gear portion that meshes with the first gear portion, 3. The transporter of claim 2, wherein the steering angle sensor is attached to the intermediate shaft.

4. the transmission mechanism further includes a spindle that is rotatable relative to the chassis and that rotates in response to driving of the steering motor, The spindle has a cylindrical worm portion, The transporter of claim 3 , wherein the intermediate shaft further comprises a worm wheel portion that meshes with the cylindrical worm portion.

5. The steering motor includes a motor shaft that rotates in response to driving of the steering motor, the motor shaft has a third gear portion, The torque limiter, A cam wheel fixed to the spindle; a movable gear that is movable relative to the spindle along an axial direction of the spindle and that meshes with the third gear portion; a coil spring that biases the movable gear toward the cam wheel relative to the spindle, The cam wheel has a cam groove, 5. The vehicle of claim 4, wherein said movable gear has a cam projection corresponding to said cam groove.

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