Drive unit and automated guided vehicle including the same

Abstract

To make traveling stability and carrying stability compatible while reducing the vehicle height of an unmanned carrier.SOLUTION: The drive shaft 40 is supported by the drive shaft holder 38 so as to be rotatable (swingable) about the support shaft 44. Thus, only the drive shaft 40 can be rolled with respect to the vehicle body 2 of the automatic guided vehicle 1. As a result, even when the automatic guided vehicle 1 travels on an uneven road surface, the horizontal state of the vehicle body 2 can be maintained, and the driving wheels 60,62 can be made to follow the unevenness of the road surface to prevent the driving wheels 60,62 from being lifted from the road surface, so that both traveling stability and transport stability can be achieved. In addition, since it is not necessary to provide a swing control plate to protrude from the second driving unit 6 as in the conventional structure in order to roll the second driving unit 6, the height of the second driving unit 6, that is, the vehicle height of the automatic guided vehicle 1 can be suppressed to be low.SELECTED DRAWING: Figure 13

Description

[Technical Field]

[0001] The present invention relates to a drive unit for driving an automated guided vehicle and an automated guided vehicle equipped with the same. [Background technology]

[0002] Japanese Patent Publication No. 8-11741 (Patent Document 1) describes an unmanned guided vehicle that has a vehicle body, a drive unit supported on the vehicle body, and casters arranged at the four corners of the vehicle body, and that transports cargo (including carts) arranged above the vehicle body to a predetermined location.

[0003] In this automated guided vehicle, the drive unit has a pair of swing control plates that protrude toward the vehicle body, and rollers arranged on the protruding ends of the pair of swing control plates abut against the vehicle body, so that the drive unit is supported by the vehicle body in a state where it is only allowed to rotate (swing) around a traveling axis extending in the traveling direction. With this configuration, the automated guided vehicle described in the above publication can roll only the drive unit relative to the vehicle body even when traveling on an uneven road surface, thereby maintaining the vehicle body in a horizontal state and causing the drive wheels of the drive unit to follow the unevenness of the road surface, preventing the drive wheels from lifting off the road surface. As a result, the automated guided vehicle described in the above publication can achieve both traveling stability and transport stability. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 8-11741 Summary of the Invention [Problem to be solved by the invention]

[0005] Recently, there has been an increasing demand for low-floor automated guided vehicles that can tow vehicles such as bogies while fitting underneath the vehicles. Because such low-floor automated guided vehicles must fit into the limited space underneath vehicles such as bogies, it is desirable to keep the vehicle height (height from the floor) of the automated guided vehicles as low as possible. On the other hand, even for low-floor automated guided vehicles, it is important to achieve both running stability and transport stability. However, in the automated guided vehicle described in the above publication, in which a swing control plate that protrudes toward the vehicle body is provided on the drive unit to enable the drive unit to roll relative to the vehicle body, there is a limit to how much the vehicle height can be reduced, and there is still room for improvement in terms of reducing the vehicle height.

[0006] The present invention has been made in view of the above, and one of its objects is to provide a technology that can achieve both running stability and transport stability while reducing the vehicle height of an automated guided vehicle. [Means for solving the problem]

[0007] The drive unit and the automated guided vehicle equipped with the same of the present invention employ the following means to achieve the above-mentioned object.

[0008] A preferred embodiment of the drive unit according to the present invention provides a drive unit for driving an automated guided vehicle. The drive unit includes a base plate, first and second drive wheels, a drive shaft that rotatably supports the first and second drive wheels, a shaft support unit integrated with the base plate, and at least one motor disposed on the base plate. The shaft support unit has an axis that extends perpendicularly to both the vertical direction and the direction in which the drive shaft extends. The shaft support unit supports the drive shaft so that the drive shaft can rotate about the axis. The motor is mechanically connected to the first and second wheels so as to drive the first and second wheels. Here, the term "integrated" in the present invention preferably encompasses an embodiment in which the shaft support unit is integrally molded with the base plate, as well as an embodiment in which the shaft support unit is integrated with the base plate by fastening members, welding, or the like.

[0009] According to the present invention, the drive shaft can rotate about an axis extending perpendicular to both the vertical direction and the direction in which the drive shaft extends, allowing only the drive shaft to roll relative to the base plate, i.e., the body of the automated guided vehicle. This allows the body to remain horizontal even when the automated guided vehicle travels on an uneven surface, and the drive wheels of the drive unit can follow the unevenness of the road surface, preventing the drive wheels from lifting off the road surface, thereby achieving both running stability and transport stability. Moreover, because the drive shaft is only supported rotatably about its axis, there is no need to provide the drive unit with a swing control plate that protrudes toward the body, as in conventional structures. This allows the height of the drive unit, i.e., the height of the automated guided vehicle, to be kept low.

[0010] According to a further aspect of the drive unit of the present invention, the drive shaft has a pair of first flat surfaces parallel to each other on its outer circumferential surface, and the shaft support portion has a pair of second flat surfaces parallel to each other, and supports the drive shaft with the first flat surface disposed between the pair of second flat surfaces.

[0011] When an automated guided vehicle pulls a carriage, a relative positional misalignment may occur between the base plate including the shaft support and the drive shaft in the direction of travel, causing contact between the shaft support and the drive shaft. According to this embodiment, the contact between the shaft support and the drive shaft can be surface contact between a first plane and a corresponding second plane, thereby reducing the surface pressure generated between the shaft support and the drive shaft. This makes it possible to prevent a decrease in the strength of the shaft support and the drive shaft.

[0012] According to a further aspect of the drive unit of the present invention, the shaft support portion has a resin plate that can come into contact with the pair of first flat surfaces, and the resin plate is disposed on the second flat surface.

[0013] According to this embodiment, when the shaft support portion and the drive shaft come into contact with each other, the drive shaft can first come into contact with the resin plate, thereby improving the sliding properties (rotational and swinging properties) of the drive shaft relative to the shaft support portion when the shaft support portion and the drive shaft come into contact with each other.

[0014] According to a further aspect of the drive unit of the present invention, the motor includes a first motor mechanically connected to the first drive wheel and a second motor mechanically connected to the second drive wheel.

[0015] According to this aspect, the rotation speeds of the first drive wheel and the second drive wheel can be controlled separately, so that the drive unit can also function as a steering unit.

[0016] According to a further embodiment of the drive unit of the present invention, the drive unit further includes a top plate. The base plate has a first rotation shaft extending in the vertical direction. The top plate has a second rotation shaft extending in the vertical direction. The first rotation shaft and the second rotation shaft are engaged to be rotatable relative to each other.

[0017] According to this aspect, the base plate can be rotated relative to the top plate. That is, by fastening the top plate to the body of the automated guided vehicle, the drive unit can be rotated relative to the body. This improves the turning ability of the automated guided vehicle.

[0018] According to a preferred embodiment of the present invention, an automated guided vehicle capable of transporting a carriage to a predetermined location is configured, the automated guided vehicle comprising a vehicle body, at least one auxiliary wheel disposed on the vehicle body, and a drive unit according to any of the above aspects of the present invention disposed on the vehicle body.

[0019] According to the present invention, since the drive unit according to any of the above-described aspects of the present invention is provided, it is possible to achieve the same effects as those achieved by the drive unit of the present invention, for example, the effect of achieving both running stability and transport stability while reducing the vehicle height of the automated guided vehicle.

[0020] According to a further aspect of the present invention, there is provided an automated guided vehicle capable of transporting a carriage to a predetermined location. The automated guided vehicle includes a vehicle body, at least one auxiliary wheel disposed on the vehicle body, and a drive unit according to any of the above aspects disposed on the vehicle body. The drive unit further includes a top plate. The motor includes a first motor mechanically connected to the first drive wheel and a second motor mechanically connected to the second drive wheel. The base plate has a first rotation shaft extending vertically. The top plate has a second rotation shaft extending vertically and is fastened to the vehicle body, the first rotation shaft and the second rotation shaft being engaged so as to be rotatable relative to each other.

[0021] According to this aspect, since the drive unit according to any one of the above-described aspects of the present invention is provided, it is possible to achieve the same effects as those achieved by the drive unit according to the present invention, for example, the effect of achieving both running stability and transport stability while reducing the vehicle height of the automated guided vehicle. Furthermore, since the rotation speeds of the first drive wheel and the second drive wheel can be controlled separately, the drive unit can also function as a steering unit. Furthermore, since the drive unit can be rotated relative to the vehicle body, the turning ability of the automated guided vehicle can be improved. [Effects of the Invention]

[0022] According to the present invention, it is possible to achieve both running stability and transport stability while reducing the vehicle height of an automated guided vehicle. [Brief explanation of the drawings]

[0023] [Figure 1] 1 is a schematic diagram showing the outline of the configuration of an automatic guided vehicle 1 according to an embodiment of the present invention. [Figure 2] 2 is a schematic diagram showing the outline of the configuration of a second drive unit 6. FIG. [Figure 3] 10 is a side view of the second drive unit 6 as seen from one side in the axial direction of the drive shaft 40. FIG. [Figure 4]FIG. 2 is a plan view of the second drive unit 6 as seen from above. [Figure 5] FIG. 2 is a perspective view showing the appearance of the top plate 20. [Figure 6] FIG. 2 is an exploded perspective view of a second drive unit 6. [Figure 7] FIG. 2 is a perspective view showing the appearance of a base plate 30. [Figure 8] 2A to 2C are three-view diagrams showing the outline of the configuration of the base plate 30. [Figure 9] 4 is an explanatory diagram showing the relative positional relationship between the base plate 30 and the drive shaft 40. FIG. [Figure 10] FIG. 10 is a plan view seen from the direction of arrow E in FIG. 9. [Figure 11] FIG. 10 is a side view seen from the direction of arrow F in FIG. 9. [Figure 12] FIG. 10 is a front view seen from the direction of arrow G in FIG. 9. [Figure 13] FIG. 4 is a cross-sectional view showing the XX section of FIG. [Figure 14] FIG. 5 is a cross-sectional view showing the YY cross section of FIG. [Figure 15] FIG. 2 is a perspective view showing the appearance of a drive shaft holder 38. [Figure 16] 10A and 10B are three-view diagrams showing the outline of the configuration of a drive shaft holder 38. [Figure 17] FIG. 17 is a cross-sectional view showing the TT cross section of FIG. [Figure 18] 10 is an explanatory diagram showing how the drive shaft 40 is assembled to the drive shaft holder 38. FIG. [Figure 19] FIG. 2 is a perspective view showing the outline of the configuration of a drive shaft 40. [Figure 20] 4 is a front view of the drive shaft 40 as seen from one side in the direction in which the axis of the through hole 42a extends. FIG. [Figure 21] 10 is an explanatory diagram showing a state in which a drive shaft 40 is supported by a drive shaft holder 38. FIG. [Figure 22] 10 is a three-view diagram showing a state in which a drive shaft 40 is supported by a drive shaft holder 38. FIG. [Figure 23] 23 is an enlarged view of a main part of the H part of FIG. 22. FIG. [Figure 24]FIG. 11 is a cross-sectional view showing the ZZ cross section of FIG. DETAILED DESCRIPTION OF THE INVENTION

[0024] Next, the best mode for carrying out the present invention will be described using examples. [Example]

[0025] As shown in FIG. 1 , an automated guided vehicle 1 according to this embodiment includes a vehicle body 2, first and second drive units 4, 6 arranged on the vehicle body 2, a pair of training wheels 8, 8 arranged on the vehicle body 2 (only one training wheel 8 is shown in FIG. 1 ), a towing hook 10 arranged on the vehicle body 2, a battery 12 arranged on the vehicle body 2 as a driving source, and a control unit 14 arranged on the vehicle body 2 for controlling the entire automated guided vehicle 1. The automated guided vehicle 1 according to this embodiment is configured as a low-floor type that tows a carriage 90 while sliding underneath the carriage 90. For ease of explanation, the left-right direction in FIG. 1 will hereinafter be referred to as the traveling direction, and in particular, the left direction in FIG. 1 will be referred to as the forward traveling direction, and the right direction in FIG. 1 will be referred to as the backward traveling direction. The left direction in FIG. 1 may also be referred to as the front side, and the right direction in FIG. 1 as the rear side.

[0026] 1, the first drive unit 4 is disposed approximately in the center of the vehicle body 2 in the traveling direction. Although not shown, the first drive unit 4 includes, for example, one DC brush motor, a differential gear device connected to the rotary shaft of the DC brushless motor, and a pair of drive wheels connected to the differential gear device. The first drive unit 4 causes the automated guided vehicle 1 to travel forward and backward by transmitting the rotation of the rotary shaft of the DC brushless motor, which is caused by the drive of the DC brushless motor, to the pair of drive wheels via the differential gear device.

[0027] As shown in Figure 1, the second drive unit 6 is disposed at the end of the vehicle body 2 in the forward travel direction. As shown in Figures 2 to 4, the second drive unit 6 is composed of a top plate 20 and a unit main body 22 supported on the top plate 20 so as to be rotatable relative to the top plate 20. The second drive unit 6 is an example of an embodiment corresponding to the "drive unit" of the present invention.

[0028] The top plate 20 is fixedly fastened to the vehicle body 2 with fastening members such as bolts. As shown in FIG. 5, the top plate 20 has a pair of guide walls 20a, 20b, a cylindrical flanged bearing holder 21, and a substantially cylindrical potentiometer holder 23. The guide walls 20a, 20b are erected on the back surface of the top plate 20 (the surface opposite the surface (front surface) facing the vehicle body 2). The guide walls 20a, 20b are disposed at the front and rear ends of the top plate 20, respectively. The guide walls 20a, 20b have an arc shape in plan view that is convex in a direction away from the center of the top plate 20. The bearing holder 21 has a shaft portion and a flange portion. The bearing holder 21 is fastened to the approximately center of the back surface of the top plate 20 via the flange portion with fastening members such as bolts so that the shaft portion protrudes from the back surface of the top plate 20. The inner diameter of the bearing holder 21 is substantially the same as the outer diameter of a ball bearing 33, which will be described later. The potentiometer holder 23 is located approximately in the center of the back surface of the top plate 20 and is fastened to the inside of the bearing holder 21 with a fastening member such as a bolt so as to protrude from the back surface of the top plate 20. The bearing holder 21 is an example of an embodiment corresponding to the "second rotation shaft" of the present invention.

[0029] As shown in FIG. 6 , the unit body 22 mainly includes a base plate 30, a flanged cylindrical rotating shaft 32, a ball bearing 33, a thrust bearing 34, a potentiometer 36, a drive shaft holder 38, a drive shaft 40 swingably supported by the drive shaft holder 38, motor units MU1 and MU2, a pair of drive wheels 60 and 62 rotatably supported by the drive shaft 40, and a travel sensor bracket 64. The second drive unit 6 can independently drive the drive wheels 60 and 62 using the motor units MU1 and MU2, and therefore functions not only as a drive device but also as a steering device. The rotating shaft 32 is an example of a configuration corresponding to a "first rotating shaft" in the present invention. The drive wheels 60 and 62 are examples of a configuration corresponding to a "first drive wheel" and a "second drive wheel" in the present invention, respectively.

[0030] 7 and 8, the base plate 30 has a main body 30a and a pair of motor fixing portions 30b, 30b integrated with the main body 30a. On the front surface side of the main body 30a (the surface facing the top plate 20), four guide rollers GR11, GR12, GR13, GR14 and four guide rollers GR21, GR22, GR23, GR24 are arranged, as shown in FIG.

[0031] As shown in Fig. 6, the guide rollers GR11, GR12, GR13, and GR14 are rotatably supported by the main body 30a at approximately the four corners of the main body 30a via shafts (not shown) arranged perpendicular to the main body 30a. More specifically, the guide rollers GR11 and GR12 are arranged at the front corners of the main body 30a, and the guide rollers GR13 and GR14 are arranged at the rear corners of the main body 30a. The guide rollers GR11 and GR12 can abut against the inner surface of the guide wall 20a of the top plate 20, and the guide rollers GR13 and GR14 can abut against the inner surface of the guide wall 20b of the top plate 20.

[0032] 6, the guide rollers GR21 and GR22 are rotatably supported on the main body 30a via shafts (not shown) arranged between the guide rollers GR11 and GR12 so as to extend radially from the axis of the rotating shaft 32. The guide rollers GR23 and GR24 are rotatably supported on the main body 30a via shafts (not shown) arranged between the guide rollers GR13 and GR14 so as to extend radially from the axis of the rotating shaft 32. The guide rollers GR21, GR22, GR23, and GR24 can abut against the rear surface of the top plate 20.

[0033] As shown in FIGS. 7 to 9, 11, and 12, the motor fixing portions 30b are erected on the back surface of the main body portion 30a (the surface opposite to the surface facing the top panel 20). As shown in FIG. 8, the motor fixing portions 30b are generally L-shaped in plan view. The motor fixing portions 30b have open notches 30c at the end opposite to the end connected to the back surface of the main body portion 30a. The width across flats Waf (see FIG. 8) of the notches 30c is set to a value slightly larger than the dimension Dts (see FIG. 22) between a pair of flat portions 42b of the drive shaft 40, which will be described later.

[0034] As shown in Figures 9 to 14, the rotating shaft 32 has a shaft portion and a flange portion integrated with the shaft portion. As shown in Figures 9, 11 to 14, the rotating shaft 32 is fastened to the approximate center of the surface of the base plate 30 via the flange portion with a fastening member such as a bolt so that the shaft portion protrudes from the surface of the base plate 30. As shown in Figures 13 and 14, the shaft portion of the rotating shaft 32 is disposed inside the shaft portion of the bearing holder 21. A ball bearing 33 is disposed between the shaft portion of the rotating shaft 32 and the inside of the shaft portion of the bearing holder 21. Furthermore, a thrust bearing 34 is disposed between the flange portion of the rotating shaft 32 and the flange portion of the bearing holder 21. This allows the base plate 30 to rotate relative to the top plate 20 via the ball bearing 33 and the thrust bearing 34.

[0035] 13 and 14, the potentiometer 36 is disposed inside the rotary shaft 32 and engaged with the potentiometer holder 23. The potentiometer 36 detects the rotational displacement of the unit body 22 relative to the top plate 20.

[0036] As shown in Figures 15 and 16, the drive shaft holder 38 is composed of a pair of plate portions 38a, 38a and a pair of extension portions 38b, 38b extending integrally from the pair of plate portions 38a, 38a so as to connect the pair of plate portions 38a, 38a. The drive shaft holder 38 is generally U-shaped in front view and generally inverted U-shaped in side view. The drive shaft holder 38 is fastened to the base plate 30 by fastening members such as bolts, with the extending end faces of the pair of extension portions 38b, 38b abutting against the back surface of the base plate 30. The drive shaft holder 38 is an example of a configuration that corresponds to a "shaft support portion" of the present invention.

[0037] As shown in FIGS. 15 and 16, each of the pair of plate portions 38a has a through hole 39a disposed approximately in the center of the pair in the longitudinal direction and a pair of circular recesses 39b disposed on either side of the through hole 39a. As shown in FIGS. 15 to 17, the pair of circular recesses 39b are disposed so as to open on the surfaces of the pair of plate portions 38a that face each other. The distance dts (see FIG. 16) between the surfaces of the pair of plate portions 38a that face each other is set to a value slightly larger than the dimension Dts between a pair of flat portions 42b and 42c of the drive shaft 40, which will be described later. As shown in FIG. 18, resin circular plates 39c are accommodated in the pair of circular recesses 39b, and in this state, the plates 39c are fastened to the plate portions 38a by fastening members such as bolts. The thickness of the circular plates 39c is set to a value slightly greater than the depth of the circular recess 39b. In other words, the circular plates 39c protrude slightly from the surface where the pair of plate portions 38a face each other. The distance between the opposing circular plates 39c is set to a value equal to or slightly greater than the dimension between a pair of flat portions 42b and 42c of the drive shaft 40 (described later). The surface where the pair of plate portions 38a face each other is an example of a "second plane" in the present invention. The axis of the through hole 39a is an example of an "axis extending in a direction perpendicular to both the vertical direction and the extension direction of the drive shaft" in the present invention. Furthermore, the circular plates 39c are an example of a "resin plate" in the present invention.

[0038] As shown in Figures 18 to 20, the drive shaft 40 has small-diameter portions 41a, 41b located at both ends in the axial direction, and a large-diameter portion 42 connecting the small-diameter portions 41a, 41b. As shown in Figure 13, sprockets SP1, SP2 and drive wheels 60, 62 are attached to the small-diameter portions 41a, 41b, respectively, in that order. As shown in Figures 18, 19, 22, and 23, the large-diameter portion 42 has a through-hole 42a located at the center in the axial direction and a pair of flat portions 42b, 42c perpendicular to the axis of the through-hole 42a. 6 and 18, with a roller bearing 43 fitted in the through hole 42a, the drive shaft 40 is aligning the through hole 42a with a pair of through holes 39a, 39a of the drive shaft holder 38, and inserting a support shaft 44 from one through hole 39a through the inner hole of the roller bearing 43 to the other through hole 39a, so that the drive shaft 40 is swingably supported by the drive shaft holder 38 (see FIGS. 21 and 22). More specifically, the drive shaft 40 is supported by the drive shaft holder 38 so as to be rotatable (swingable) about the support shaft 44, whose axis extends in a direction perpendicular to both the vertical direction (the axial direction of the shaft portion of the rotating shaft 32) and the axial direction of the drive shaft 40 (arrows OD in FIGS. 21 and 22). When the drive shaft 40 is supported by the drive shaft holder 38, the pair of flat surfaces 42b, 42c face the plate portions 38a, 38a, particularly the circular plates 39c, as shown in Fig. 23, and also face the notches 30c, 30c of the motor fixing portions 30b, 30b, as shown in Fig. 24. This allows for surface contact between the drive shaft 40 and the drive shaft holder 38, and between the drive shaft 40 and the motor fixing portions 30b, 30b, when the drive shaft 40 moves in the axial direction of the support shaft 44 (the up-down direction in Fig. 23, the left-right direction in Fig. 24). 23, when the drive shaft 40 moves in the axial direction of the support shaft 44, the pair of flat surfaces 42b, 42c first come into contact with the circular plates 39c, 39c, rather than with the surfaces of the plate portions 38a, 38a of the drive shaft holder 38 that face each other. The flat surfaces 42b, 42c are an example of an embodiment that corresponds to the "first flat surface" of this invention.

[0039] As shown in FIG. 14, motor units MU1 and MU2 are fastened to base plate 30 with fastening members such as bolts. As shown in FIG. 6, motor units MU1 and MU2 have motors M1 and M2 and gearboxes GB1 and GB2 mechanically connected to the motors M1 and M2. Sprockets SP3 and SP4 are attached to the output shafts (not shown) of gearboxes GB1 and GB2, respectively. A chain CH1 is wound around sprockets SP1 and SP3, and a chain CH2 is wound around sprockets SP2 and SP4. Motors M1 and M2 are examples of embodiments corresponding to the "first motor" and "second motor" of the present invention, respectively.

[0040] As shown in FIG. 14, the travel sensor bracket 64 is fastened to the base plate 30 with fastening members such as bolts. A travel sensor (not shown) and a marker sensor (not shown) are attached to the travel sensor bracket 64. The travel sensor detects a guide band (not shown) (e.g., a magnetic tape) installed on the floor surface so that the automated guided vehicle 1 can travel along a preset travel route. The marker sensor detects a marker (not shown) installed on the floor surface near the guide band in order to cause the automated guided vehicle 1 to execute a predetermined command, such as "stop traveling" or "accelerate."

[0041] The towing hook 10 is configured to be changeable between a state in which it can engage with the frame 92 of the bogie 90 and a state in which it can disengage from the frame 92. Specifically, as shown in FIG. 1, the towing hook 10 is in a towing-enabled state by protruding from the top surface of the vehicle body 2, and in a non-towing state by retracting inside the vehicle body 2.

[0042] The battery 12 is used as a power source for driving the motors M1 and M2 and the control unit 14.

[0043] The control unit 14 is configured as a microprocessor centered around a CPU, and in addition to the CPU, is equipped with a ROM for storing processing programs, a RAM for temporarily storing data, and input / output and communication ports (not shown). Position deviation signals from travel sensors, command signals from marker sensors, object detection signals from obstacle sensors (not shown), signals required for managing the battery 12 (e.g., terminal voltage from a voltage sensor (not shown) installed between the terminals of the battery 12 and current detected by a current sensor (not shown)), and the rotation speed of the drive wheels 60, 62 from a rotation speed sensor (not shown) are input to the control unit 14 via the input ports. Drive signals to the motors M1, M2 and operation signals to the tow hook 10 and the lift device 16 are also output from the control unit 14 via the output ports.

[0044] Next, the operation of the thus configured automated guided vehicle 1, particularly the operation when the automated guided vehicle 1 travels on an uneven road, will be described. When the automated guided vehicle 1 starts traveling, the CPU of the control unit 14 reads detection signals from a travel sensor (not shown) and command signals from a marker sensor (not shown), and executes processing to drive and control the first and second drive units 4, 6 so that the automated guided vehicle 1 travels along the guided lane. When the automated guided vehicle 1 enters under the carriage 90 and reaches a position where it can tow the carriage 90 (see FIG. 1), the marker sensor (not shown) detects a marker (not shown) placed on the floor corresponding to that position. The marker stores a temporary stop command for the automated guided vehicle 1, a drive command for the towing hook 10 and the lift device 16, and a command to restart the automated guided vehicle 1. When the marker sensor detects the marker, it outputs a command signal to the control unit 14.

[0045] When a command signal is input from the marker sensor, the CPU of the control unit 14 temporarily stops the automated guided vehicle 1 and controls the driving of the towing hook 10 and the lift device 16. As a result, the lift device 16 abuts against the frame 92 of the carriage 90, and at least the front wheels of the carriage 90 are lifted from the floor surface F. Here, part of the weight of the carriage 90 acts on the pair of drive wheels of the first drive unit 4 and the pair of drive wheels 60, 62 of the second drive unit 6 via the lift device 16. This improves the gripping force of the pair of drive wheels of the first drive unit 4 and the pair of drive wheels 60, 62 of the second drive unit 6. Note that in this embodiment, at least part of the weight of the carriage 90 acting on the second drive unit 6 is supported not only by the thrust bearing 34 but also by the guide rollers GR21, GR22, GR23, GR24 and the top plate 20, so that the load acting on the thrust bearing 34 can be reduced. This eliminates the need to use a thrust bearing 34 with excessively high load-bearing capacity, thereby preventing the thrust bearing 34 from becoming larger. As a result, it is possible to make the second drive unit 6 more compact. Moreover, because the guide rollers GR21, GR22, GR23, and GR24 roll on the back side of the top plate 20, the unit body 22 can rotate smoothly relative to the top plate 20.

[0046] Meanwhile, when the towing hook 10 is driven, the towing hook 10 engages with the frame 92 of the bogie 90. Then, with the lift device 16 lifting the front wheels of the bogie 90 from the floor surface F and with the towing hook 10 engaged with the frame of the bogie 90, the CPU of the control unit 14 controls the drive of the first and second drive units 4, 6 to restart the automated guided vehicle 1. In this way, the automated guided vehicle 1 tows the bogie 90 to the desired location. Here, in this embodiment, when the automated guided vehicle 1 tows the bogie 90, at least a portion of the tractive force (a force in the direction opposite to the direction in which the bogie 90 is towed) acting on the second drive unit 6 (rotation shaft 32) is received not only by the ball bearing 33 but also by the guide rollers GR11, GR12 and the guide wall 20a, or the guide rollers GR13, GR14 and the guide wall 20b. Therefore, there is no need to use a ball bearing 33 with excessively high radial load resistance. This prevents the ball bearing 33 from becoming larger, thereby enabling the second drive unit 6 to be made more compact. Moreover, the guide rollers GR11 and GR12 roll on the inner surface of the guide wall 20a, and the guide rollers GR13 and GR14 roll on the inner surface of the guide wall 20b, allowing the unit body 22 to rotate smoothly relative to the top plate 20. When a traction force is applied to the second drive unit 6, the drive shaft 40 may move in the axial direction of the support shaft 44 and come into contact with the drive shaft holder 38 and the motor fixing parts 30b. However, as described above, the drive shaft 40 is in surface contact with the drive shaft holder 38 (circular plates 39c) and the motor fixing parts 30b, and therefore the surface pressure generated between the drive shaft 40 and the drive shaft holder 38 (circular plates 39c) and the motor fixing parts 30b can be kept small. This makes it possible to prevent a decrease in strength and an increase in wear of the drive shaft 40, drive shaft holder 38 (circular plates 39c, 39c), and motor fixing parts 30b, 30b. Note that, since the drive shaft 40 is configured to abut against the resin circular plates 39c, 39c instead of the drive shaft holder 38, the drive shaft 40 can be smoothly swung (rotated, rolled).

[0047] If the roadway on which the automated guided vehicle 1 travels is uneven, the drive shaft 40 of the second drive unit 6 swings (rotates, rolls) around the support shaft 44, causing the drive wheels 60, 62 to follow the unevenness of the roadway (road surface). This prevents the drive wheels 60, 62 from lifting off the roadway (road surface). Moreover, in this embodiment, the drive shaft 40 swings (rotates, rolls) relative to the base plate 30. That is, only the drive shaft 40 swings (rotates, rolls). This allows the vehicle body 2 to maintain a horizontal position. As a result, both the running stability and transport stability of the automated guided vehicle 1 can be achieved with a simple configuration. Note that, because only the drive shaft 40 swings (rotates, rolls), there is no need to provide the second drive unit 6 with a swing control plate that protrudes toward the vehicle body 2 (vertically upward), as in conventional structures. As a result, the height of the second drive unit 6, that is, the vehicle height of the automatic guided vehicle 1, can be kept low.

[0048] According to the automated guided vehicle 1 according to the present embodiment described above, the drive shaft 40 of the second drive unit 6 is supported by the drive shaft holder 38 so as to be rotatable (swingable) about the support shaft 44 extending in a direction perpendicular to both the vertical direction (the axial direction of the shaft portion of the rotation shaft 32) and the axial direction of the drive shaft 40, and therefore only the drive shaft 40 can be rolled relative to the body 2 of the automated guided vehicle 1. As a result, even when the automated guided vehicle 1 travels on an uneven road surface, the body 2 can be maintained in a horizontal state, and the drive wheels 60, 62 of the second drive unit 6 can be made to follow the unevenness of the road surface to prevent the drive wheels 60, 62 from lifting off the road surface, thereby achieving both driving stability and transport stability. Furthermore, since the drive shaft 40 is only supported rotatably around the support shaft 44, there is no need to provide the drive unit with a swing control plate that protrudes in the direction in which the vehicle body is positioned (vertically upward), as in conventional structures, and therefore the height of the second drive unit 6, i.e., the vehicle height of the unmanned guided vehicle 1, can be kept low.

[0049] Furthermore, according to the automated guided vehicle 1 of this embodiment, the drive shaft 40 has a pair of flat surfaces 42b, 42c, and the drive shaft 40 is supported on the drive shaft holder 38 so that the pair of flat surfaces 42b, 42c face the pair of plate portions 38a, 38a, in particular the circular plates 39c, 39c arranged on each of the pair of plate portions 38a, 38a, and the notches 30c, 30c of the motor fixing portions 30b, 30b.Therefore, when the automated guided vehicle 1 tows the carriage 90, a relative positional shift occurs between the drive shaft 40 and the drive shaft holder 38 and the base plate 30 (motor fixing portions 30b, 30b) in the traveling direction of the automated guided vehicle 1, and if contact occurs between the drive shaft 40 and the drive shaft holder 38 and the base plate 30 (motor fixing portions 30b, 30b), the contact can be made into surface contact. This reduces the surface pressure generated between the drive shaft 40 and the drive shaft holder 38 and the base plate 30. As a result, it is possible to suppress a decrease in the strength of the drive shaft 40, the drive shaft holder 38, and the base plate 30. Since the drive shaft 40 and the drive shaft holder 38 are configured to contact each other via the resin circular plates 39c, 39c, it is possible to improve the sliding properties (rotational properties, swingability) of the drive shaft 40 relative to the drive shaft holder 38 when the drive shaft 40 and the drive shaft holder 38 come into contact with each other.

[0050] Furthermore, in the automated guided vehicle 1 according to this embodiment, the second drive unit 6 has motor units MU1 and MU2, so that it can independently drive the drive wheels 60 and 62. This allows the second drive unit 6 to function not only as a drive device but also as a steering device.

[0051] Furthermore, according to the automated guided vehicle 1 of this embodiment, the second drive unit 6 is configured to be rotatable relative to the vehicle body 2 of the automated guided vehicle 1, so that the turning ability of the automated guided vehicle 1 can be improved.

[0052] In this embodiment, the second drive unit 6 is configured to function not only as a drive device but also as a steering device, but the second drive unit 6 may also be configured to function only as a drive device. In this case, the second drive unit 6 may be configured to include one motor and a differential gear device connected to the rotary shaft of the motor, and the drive wheels 60, 62 may be connected to the differential gear device via a transmission member such as a chain.

[0053] The present embodiment shows an example of a mode for carrying out the present invention, and therefore the present invention is not limited to the configuration of the present embodiment.

[0054] <Additional Notes> In view of the above-mentioned gist of the invention, the automated guided vehicle according to the present invention can be configured in the following aspects. (Aspect 1) "A drive unit for driving an automated guided vehicle, A base plate and first and second drive wheels; a drive shaft that rotatably supports the first and second drive wheels; a shaft support portion that is integrated with the base plate, has an axis that extends in a direction perpendicular to both the vertical direction and the extending direction of the drive shaft, and supports the drive shaft so that the drive shaft can rotate around the axis; at least one motor mechanically connected to the first and second drive wheels so as to be able to drive the first and second drive wheels and disposed on the base plate; A drive unit equipped with (Aspect 2) "The drive shaft has a pair of first flat surfaces parallel to each other on its outer circumferential surface, The shaft support portion has a pair of second flat surfaces parallel to each other, and supports the drive shaft in such a manner that the first flat surface is disposed between the pair of second flat surfaces. The drive unit according to the first aspect. (Aspect 3) The pair of second flat surfaces have resin plates that can come into contact with the pair of first flat surfaces. The drive unit according to aspect 2. (Aspect 4) "The motor includes a first motor mechanically connected to the first drive wheel and a second motor mechanically connected to the second drive wheel. The drive unit according to any one of the first to third aspects. (Aspect 5) "It has more tops, the base plate has a first rotation axis extending in a vertical direction, the top plate has a second rotation axis extending in a vertical direction, The first rotating shaft and the second rotating shaft are engaged to be capable of rotating relative to each other. The drive unit according to 4 above. (Aspect 6) "An automated guided vehicle that can transport a cart to a specified location, The car body and At least one auxiliary wheel disposed on the vehicle body; The drive unit according to any one of the first to fifth aspects, which is disposed on the vehicle body; An automated guided vehicle equipped with (Aspect 7) "The top plate is fastened to the vehicle body. The automated guided vehicle according to aspect 6, which is dependent on aspect 5. [Explanation of symbols]

[0055] 1. Automated guided vehicle (automated guided vehicle) 2. Body (body) 4. First drive unit 6 Second drive unit (drive unit) 8 Training wheels (training wheels) 10 Tow Hook 12 Battery 14 Control Unit 16 Lifting device 20 Top plate (top plate) 20a Guide Wall 20b Guide wall 21 Bearing holder (second rotating shaft) 23 Potentiometer holder 22 Unit body 30 Base Plate (Base Plate) 30a Main body 30b Motor fixing part 30c notch 32 Rotation axis (first rotation axis) 33 Ball bearings 34 Thrust bearing 36 Potentiometer 38 Drive shaft holder (shaft support part) 38a Plate section 38b Extension 39a through hole 39b Circular recess 39c Round Plate (Resin Plate) 40 Drive shaft (drive shaft) 41a Small diameter section 41b Small diameter section 42 Large diameter section 42a through hole 42b Plane part (1st plane) 42c Plane part (1st plane) 43 Roller bearing 44 Support shaft 60 Drive wheel (first drive wheel) 62 Drive wheel (second drive wheel) 64 Travel sensor bracket 90 carts 92 frames MU1 motor unit MU2 motor unit M1 Motor (Motor, 1st Motor) M2 motor (motor, second motor) GB1 Gearbox GB2 Gearbox SP1 sprocket SP2 sprocket SP3 sprocket SP4 sprocket CH1 Chain CH2 Chain GR11 guide roller GR12 guide roller GR13 guide roller GR14 guide roller GR21 guide roller GR22 guide roller GR23 guide roller GR24 guide roller Waf (width across flats) Dts: Dimension between the pair of flat portions 42b and 42c dts: Distance between the surfaces of the pair of plate portions 38a, 38a facing each other

Claims

1. A drive unit for driving an automated guided vehicle, A base plate and first and second drive wheels; a drive shaft that rotatably supports the first and second drive wheels; a shaft support portion that is integrated with the base plate, has an axis that extends in a direction perpendicular to both the vertical direction and the extending direction of the drive shaft, and supports the drive shaft so that the drive shaft can rotate around the axis; at least one motor mechanically connected to the first and second drive wheels so as to be able to drive the first and second drive wheels and disposed on the base plate; A drive unit comprising:

2. the drive shaft has a pair of first flat surfaces parallel to each other on an outer circumferential surface thereof, The shaft support portion has a pair of second flat surfaces parallel to each other, and supports the drive shaft in such a manner that the first flat surface is disposed between the pair of second flat surfaces.

2. The drive unit according to claim 1.

3. the shaft support portion has a resin plate that can come into contact with the pair of first flat surfaces, The resin plate is disposed on the second plane.

3. The drive unit according to claim 2.

4. The motor includes a first motor mechanically connected to the first drive wheel and a second motor mechanically connected to the second drive wheel. A drive unit according to any one of claims 1 to 3.

5. It also has a top plate, the base plate has a first rotation axis extending in a vertical direction, the top plate has a second rotation axis extending in a vertical direction, The first rotating shaft and the second rotating shaft are engaged to be capable of rotating relative to each other.

5. A drive unit according to claim 4.

6. An automated guided vehicle capable of transporting a carriage to a predetermined location, The car body and At least one auxiliary wheel disposed on the vehicle body; The drive unit according to claim 1, which is disposed on the vehicle body; An automated guided vehicle equipped with

7. An automated guided vehicle capable of transporting a carriage to a predetermined location, The car body and At least one auxiliary wheel disposed on the vehicle body; The drive unit according to claim 1, which is disposed on the vehicle body; Equipped with The drive unit further includes a top plate, the motor includes a first motor mechanically connected to the first drive wheel and a second motor mechanically connected to the second drive wheel; the base plate has a first rotation axis extending in a vertical direction, the top plate has a second rotation axis extending in a vertical direction and is fastened to the vehicle body; The first rotating shaft and the second rotating shaft are engaged to be capable of rotating relative to each other. Automated guided vehicle.

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