Automated guided vehicle

Abstract

Provided is an automated guided vehicle in which a high-stroke and flat lifting device is mounted to achieve lowering of the floor of the automated guided vehicle, and that can be adapted to a load of a low path line and can handle the path lines of a wide variety of loads by the one identical vehicle. The automated guided vehicle comprises a carriage provided with a driving wheel and configured so as to be able to freely travel, and a lifting device 4 provided on the carriage so as to be freely liftable and lowerable. The lifting device 4 includes: a device lifting part 13 having, on a lower surface, a load placing part S for placing a load and having a cam follower guide surface G1 parallel to a traveling surface of the carriage; a device foundation part 12 fixed to a lower fixed position of the device lifting part 13 and having a cam follower guide groove G2 extending in a direction parallel to a traveling surface of the carriage; a link mechanism 28 having first and second link arms 19, 20 of which intermediate parts are pin-joined and connected to each other in an X-shape rotatably around the joint part; and a drive mechanism 29 for moving a first cam follower 22 of the first link arm 19.

Description

automated guided vehicle

[0001] The present invention relates to an automated guided vehicle.

[0002] In recent years, automated guided vehicles (AGVs) that can automatically transport materials without human intervention have been used in factories and logistics sites. Some of these AGVs are equipped with a lifting device. The AGVs with the lifting device move under a target load, such as a box pallet, and then lift the load using the lifting device to transport it to the next destination. For example, Patent Document 1 discloses a lift table for an AGV that lifts and lowers a load by extending and contracting the links of a pantograph mechanism by raising and lowering a screw of a worm jack driven by a motor. Patent Document 2 discloses a guided AGV that moves the swing fulcrum via a female screw member provided on a swing fulcrum member of a link mechanism and a male screw member threadedly engaged with the female screw member using a motor to move the swing fulcrum and perform the lifting operation of the link mechanism.

[0003] JP-A-62-244897 JP-A-59-220446

[0004] Here, lifting devices are required to be able to lift and lower loads along low or diverse pass lines. In contrast, the lift table described in Patent Document 1 employs a worm jack that moves vertically during lifting and lowering. Therefore, depending on the height of the worm jack, it may be difficult to achieve both a flat lifting device and a long stroke. Furthermore, because the motor output shaft is concentrically connected to the jack stroke input shaft, the motor is positioned midway through the device, which may affect the height of the lifting device depending on the motor's size. This hinders the flattening of automated guided vehicles, and may result in problems such as the inability of the automated guided vehicle to crawl under the load depending on the load's pass line, or the need to provide different automated guided vehicles for different pass lines depending on the differences between multiple pass lines. In the lifting device described in Patent Document 2, the horizontal linear motion mechanism, which includes a motor and a rotating screw shaft, is connected to a swing fulcrum. Therefore, the position of the horizontal linear motion mechanism depends on the position of the swing fulcrum, which may affect the height of the lifting device, resulting in the same problems as those described in Patent Document 1.

[0005] The present invention has been made in view of the above-mentioned circumstances, and the problem that the present invention aims to solve is to provide an unmanned guided vehicle that can accommodate loads on low pass lines and pass lines for a wide variety of loads with the same vehicle, by locating the drive mechanism of the lifting device at a low position to realize a lifting device with a long stroke and a low profile, and by installing this lifting device, can realize a low-floor unmanned guided vehicle.

[0006] The present invention employs the following means to solve the above problems. That is, an automated guided vehicle of the present invention comprises a carriage equipped with drive wheels and configured to be freely movable, and a lifting device provided on the carriage so as to be able to be raised and lowered, the lifting device having a load placement section for placing a load thereon and having a cam follower guide surface on its underside parallel to the running surface of the carriage, an equipment base section fixed to a fixed position below the equipment lifting section and having a cam follower guide groove extending in a direction parallel to the running surface of the carriage, and first and second link arms having intermediate sections joined by a pin and connected to each other in an X-shape so as to be rotatable about the joint, a first end of the first link arm being rotatably supported at a fixed position on the equipment lifting section, and a first cam follower being attached to a second end of the first link arm. the first cam follower is engaged with the cam follower guide groove, a first end of the second link arm is rotatably supported at a fixed position on the device base, a second cam follower is provided at the second end of the second link arm, and the second cam follower is engaged with the cam follower guide surface; and a drive mechanism that moves the first cam follower in the parallel direction, wherein the drive mechanism is provided on the device base and comprises: a screw shaft that is provided on the device base and extends in the parallel direction; a moving member that is screwed onto the screw shaft and supported so as not to be rotatable relative to the screw shaft, and on which the first cam follower is provided; and a drive source that rotationally drives the screw shaft.

[0007] In one aspect of the present invention, the moving member is provided with an auxiliary cam follower that is spaced apart from the first cam follower in the traveling direction of the carriage and that engages with the cam follower guide groove.

[0008] In one aspect of the present invention, the moving member is provided so as to extend in the width direction of the carriage, and the link mechanism is provided on each of the left and right ends of the moving member.

[0009] In one aspect of the present invention, the first and second lifting devices are provided spaced apart in the traveling direction of the carriage.

[0010] In one aspect of the present invention, the device lifting section comprises a lifting section main body with the second cam follower engaged on its underside, a loading platform placed on the lifting section main body, and a cover rotatably connected to one end of the loading platform in the front or rear of the carriage in the direction of travel, the cover having its lower end slidably abutting the upper surface of the carriage.

[0011] In one aspect of the present invention, the first cam follower comprises an outer ring and a fixed shaft portion that are arranged in the cam follower guide groove, the fixed shaft portion is fixed to the movable member, the movable member is provided with a cylindrical wall portion that surrounds the fixed shaft portion, and the first link arm is attached so as to be freely rotatable around the cylindrical wall portion.

[0012] According to the present invention, by locating the drive mechanism of the lifting device at a low position, a long-stroke and flat lifting device can be realized, and by installing this lifting device, an unmanned guided vehicle can be made to have a low floor, making it possible to provide an unmanned guided vehicle that is suitable for loads with low pass lines and can handle the pass lines of a wide variety of loads with the same vehicle.

[0013] Fig. 1 is a top view of an automated guided vehicle according to an embodiment of the present invention. Fig. 2 is a side view of Fig. 1. Fig. 2 is a top view of a lifting device according to an embodiment of the present invention. Fig. 3 is a side view of Fig. 3. Fig. 3 is a cross-sectional view taken along the arrows A-A in Fig. 3. Fig. 4 is a cross-sectional view taken along the arrows B-B in Fig. 4. Fig. 4 is a cross-sectional view taken along the arrows C-C in Fig. 4. Fig. 4 is a side view showing the mounting relationship of a lifting device for an automated guided vehicle according to an embodiment of the present invention. Fig. 5 is a cross-sectional view taken along the arrows D-D in Fig. 4.

[0014] An embodiment of the present invention will now be described with reference to the accompanying drawings. (Embodiment) Fig. 1 shows a top view of an automated guided vehicle according to this embodiment, and Fig. 2 shows its side view. An automated guided vehicle 10 of the present invention comprises a carriage 1 equipped with drive wheels 2 and configured to be freely movable, and a lifting device 4 provided on the carriage 1 so as to be able to move up and down. The drive wheels 2 are disposed on the central side of the carriage 1, and driven wheels 3 are disposed on the front and rear sides, with a total of one set (two) of lifting devices 4 disposed at the front and rear of the carriage 1. A load presence detection sensor 5 is disposed on top of the lifting device 4.

[0015] A top view of the lifting device 4 is shown in Fig. 3, and a side view is shown in Fig. 4. A cross-sectional view taken along the line A-A of the top view (Fig. 3) is shown in Fig. 5, a cross-sectional view taken along the line B-B of the side view (Fig. 4) is shown in Fig. 6, and a cross-sectional view taken along the line C-C of the side view (Fig. 4) is shown in Fig. 7. For simplification, components 24 and 25 (link connecting members, described later) are omitted from Fig. 6.

[0016] 4, the lifting device 4 includes a device lifting section 13, a device base section 12, a link mechanism 28, and a drive mechanism 29. The device lifting section 13 has a load placement section S on which a load is placed, and is provided on its underside with a cam follower guide surface G1 that is parallel to the traveling surface of the carriage. The device base section 12 is fixed in a fixed position below the device lifting section 13, and has a cam follower guide groove G2 that extends in a direction parallel to the traveling surface of the carriage 1. The link mechanism 28 has a first link arm 19 and a second link arm 20 which are connected at their middle portions by a pin and which are connected in an X-shape so as to be freely rotatable around the joint, and the first end 19a of the first link arm 19 is rotatably supported at a fixed position on the device lifting section 13, a first cam follower 22 is provided at the second end 19b of the first link arm 19, and the first cam follower 22 is engaged with the cam follower guide groove G2, the first end 20a of the second link arm 20 is rotatably supported at a fixed position on the device base section 12, and a second cam follower 21 is provided at the second end 20b of the second link arm 20, and the second cam follower 21 is engaged with the cam follower guide surface G1.

[0017] The drive mechanism 29 moves the first cam follower 22 in a direction parallel to the running surface of the bogie 1. As shown in Fig. 5, the drive mechanism 29 is provided on the device base 12 and includes: a screw shaft 14 extending in a direction parallel to the running surface of the bogie 1; a moving member 15 threadedly attached to the screw shaft 14, supported so as not to be rotatable relative to the screw shaft 14, and to which the first cam follower 22 shown in Fig. 4 is coupled; and a motor (drive source) 11 that rotationally drives the screw shaft 14.

[0018] As shown in Figures 4 and 7, the moving member 15 is provided with an auxiliary cam follower 23 that is spaced apart from the first cam follower 22 in the traveling direction of the carriage 1 and engages with the cam follower guide groove G2. As shown in Figure 6, the moving member 15 is provided so as to extend in the width direction of the carriage 1 (the up-and-down direction on the paper), and link mechanisms 28, 28 are provided on both the left and right ends of the moving member 15. As shown in Figures 1 and 2, first and second lifting devices 4, 4 are provided with an interval in the traveling direction of the carriage 1.

[0019] Figure 8 is a side view showing the mounting relationship of the lifting device 4 of the automated guided vehicle 10 according to this embodiment. As shown in Figure 8, the device lifting section 13 includes a lifting section main body 30 with the second cam follower 21 engaged on its underside, a load receiving platform 31 placed on the lifting section main body 30, and a cover 32 rotatably connected to one end of the load receiving platform 31 in the front or rear direction of travel of the carriage 1, the lower end of which slidably abuts against the upper surface of the carriage 1. Note that the cover 32 and related members are omitted from Figures 4 and 5 for simplification.

[0020] The components of the automated guided vehicle 10 configured as described above will be described in further detail below. As shown in Figures 4 to 7, the device base 12 is composed of a bottom plate 12a and a guide member 12b that rises vertically upward from the bottom plate 12a. The body of the motor 11 is fixed to the bottom plate 12a, and a fixed shaft member 17 is fixed to the guide member 12b. The guide member 12b is provided with a cam follower guide groove G2 that extends in a direction parallel to the running surface of the carriage 1, and the first cam follower 22 and the auxiliary cam follower 23 are engaged in the guide member 12b. The cam follower guide groove G2 is provided with a rolling surface Y that sandwiches the upper and lower outer rings of the first cam follower 22 and the auxiliary cam follower 23.

[0021] 5, a screw shaft 14 is coupled to the output shaft of the motor 11. A moving member 15 is provided with a female thread corresponding to the screw shaft 14, and is connected to the screw shaft 14 by thread engagement.

[0022] As shown in Figures 6 and 7, two sets of link mechanisms 28, 28, each consisting of members 16 to 23, are arranged on either side of the moving member 15. The fixed shaft portion (inner ring bearing shaft) of the auxiliary cam follower 23 and the fixed shaft portion (inner ring bearing shaft) of the first cam follower 22 shown in Figure 4 are fixed to the moving member 15. A second link arm 20 is connected to the fixed shaft member 17 in a state where it has a degree of freedom of rotation about the axis 17. A first link arm 19 is rotatably attached to the fixed shaft portion of the first cam follower 22.

[0023] Here, the coupled state of the moving member 15, first cam follower 22, and first link arm 19 will be described in further detail. Figure 9 is a cross-sectional view taken along the line D-D in Figure 4. As shown in Figure 4, the first cam follower 22 includes an outer ring 53 and a fixed shaft portion 51 that are disposed within the cam follower guide groove G2. The outer ring 53 is mounted with a plurality of needle rollers 55 interposed therebetween so that the outer ring 53 can rotate around the fixed shaft portion 51 while rolling the plurality of needle rollers 55.

[0024] The moving member 15 is provided with a cylindrical wall portion 41 that protrudes laterally, and the fixed shaft portion 51 of the first cam follower 22 is inserted into the inside of the cylindrical wall portion 41. A male thread is formed on the tip end 57 of the fixed shaft portion 51, and is screwed into a female thread formed on the inside of the moving member 15. The first link arm 19 is provided with a circular opening K at its second end 19b, and is fitted onto the outer periphery of the cylindrical wall portion 41 of the moving member 15 with a bearing 42 interposed therein. A spacer 43 is disposed between the first link arm 19 and the moving member 15, so that the gap between the first link arm 19 and the moving member 15 is constant. With this configuration, the first link arm 19 is rotatably attached around the cylindrical wall portion 41 via the cylindrical bearing 42.

[0025] The outer ring 53 is movable in the front-to-back direction of the page (direction perpendicular to the page) along a cam follower guide groove G2 provided in the device base 12. With this configuration, when the movable member 15 moves in the front-to-back direction of the page, the outer ring 53 of the first cam follower 22 moves while being guided by the cam follower guide groove G2. Meanwhile, the first link arm 19 rotates relative to the bearing 42, and the first link arm 19 swings around the axis of a fixed shaft member 18 (FIG. 4), which will be described later.

[0026] The swing shaft member 16 is fixed to the first link arm 19, and the second link arm 20 is connected to the swing shaft member 16 in a state having a degree of freedom of rotation about the axis of the swing shaft member 16. As a result, the first link arm 19 and the second link arm 20 are connected to each other in a state having a degree of freedom of rotation about the swing axis X in FIG.

[0027] As shown in Figures 4 and 5, a fixed shaft portion (inner ring shaft of bearing) of a second cam follower 21 is fixed to a second end portion 20b of the second link arm 20. A set (two pieces) of first link arms 19 are fixed by a link connecting member 24. A set (two pieces) of second link arms 20 are fixed by a link connecting member 25. A fixed shaft member 18 is fixed to the device lifting unit 13. A cam follower guide surface G1 is provided on the device lifting unit 13, and is configured to contact the upper side of the outer ring of the second cam follower 21. The first link arm 19 is connected to the fixed shaft member 18 in a state where it has a degree of freedom of rotation about the axis of the fixed shaft member 18.

[0028] As shown in Figure 8, the device base 12 of the lifting device 4 is fixed to the bogie 1. In order to flatten the vehicle, a partial cutout hole is provided in the bottom surface of the bogie 1 so that part of the device base 12 of the lifting device can be brought as close as possible to the running floor side. A load receiving platform 31 is installed on the top of the lifting section main body 30 of the lifting device 4. A cover 32 is connected to the load receiving platform 31 via a hinge 33. Because the hinge 33 has a degree of freedom of rotation, the part of the cover 32 opposite the fixed part of the hinge 33 is in contact with the top surface of the bogie 1.

[0029] The operation of the automated guided vehicle configured as described above will now be described. The vehicle travels by rotating the drive wheels 2, and the vehicle is steered by the speed difference between the pair of drive wheels 2. After the automated guided vehicle 10 stops traveling under the target load, it activates the lifting device 4 to lift a portion of itself, thereby lifting the load. At this time, the pair of lifting devices 4, 4 operate independently. The load presence detection sensor 5 is used to monitor whether the load has been lifted correctly, and a control device (not shown) of the automated guided vehicle 10 makes a determination based on the signal output state of the load presence detection sensor 5. Note that the movement of the automated guided vehicle may be performed by any method, such as line tracing, landmark detection, or SLAM (Simultaneous Localization and Mapping), and as these are well-known techniques, a description of these methods will be omitted here.

[0030] In the lifting device 4, the screw shaft 14 rotates in conjunction with the rotation of the output shaft of the motor 11. The rotation of the screw shaft 14 causes the moving member 15, which is connected by a threaded engagement, to move in the axial direction of the screw shaft 14. As the moving member 15 moves, the first cam follower 22 and the auxiliary cam follower 23, which are coupled to the moving member 15, move within the cam follower guide groove G2 along the rolling surface Y. When the moving member 15 moves, a moment acts on the screw shaft 14 because the position of the first cam follower 22 is offset from the central axis of the screw shaft 14. However, in this configuration, by adding the auxiliary cam follower 23, the moment acting on the screw shaft 14 is supported by the rolling surface Y of the auxiliary cam follower 23 and the cam follower guide groove G2. When the moving member 15 moves, the second end 19b of the first link arm 19 also moves in conjunction with the movement of the first cam follower 22.

[0031] The first link arm 19 is connected to the device lifting unit 13 by a fixed shaft member 18 with a degree of rotational freedom, and the second link arm 20 is connected to the device base unit 12 by a fixed shaft member 17 with a degree of rotational freedom. The first link arm 19 and the second link arm 20 are connected to each other via a swing shaft member 16 with a degree of rotational freedom. Furthermore, the moving member 15 and the fixed shaft portion 51 of the first cam follower 22 are fixedly attached, and the fixed shaft portion 51 of the first cam follower 22 and the first link arm 19 are connected to each other with a degree of rotational freedom. Therefore, when the first cam follower 22 moves due to the movement of the movable member 15, the first link arm 19 rotates about the axis of the fixed shaft member 18, and at the same time, the fixed shaft portion 51 of the first cam follower 22 fixed to the movable member 15 and the first link arm 19 rotate about the axis of the first cam follower 22, and the swing shaft member 16 also moves. In conjunction with this movement, the second link arm 20 rotates about the fixed shaft member 17.

[0032] These operations cause the device lifting unit 13, which is joined to the first link arm 19 with a degree of rotational freedom, to move vertically via the fixed shaft member 18. The posture of the device lifting unit 13 is kept horizontal by the outer ring of the second cam follower 21 joined to the second link arm 20 supporting the cam follower guide surface G1 provided on the device lifting unit 13. Link joining members 24 and 25 improve mechanical strength by joining the link arms 19 and 20, respectively.

[0033] The vertical movement of the device lifting unit 13 causes the load receiving platform 31 installed on the top surface of the lifting unit main body 30 to move vertically in conjunction with the load receiving platform 31. The load receiving platform 31 maintains contact with the load receiving platform 31 solely due to its own weight. Therefore, if a structure intrudes between the load receiving platform 31 and the cart 1, only the weight of the load receiving platform 31 acts as a force on the structure, and the load receiving platform 31 itself separates from the lifting unit main body 30. However, the degrees of freedom of the automated guided vehicle 10 in the straight and lateral directions are limited by the shapes of the components of both the lifting unit main body 30 and the load receiving platform 31, so that horizontal movement beyond a certain level cannot occur. The load receiving platform 31 comes into contact with the bottom of the load to be transported by the automated guided vehicle 10, moving (lifting) the load vertically. The cover 32, which is fixed to the loading platform 31 via hinges 33, has a degree of rotational freedom, so that it can be tilted down by its own weight while coming into contact with the upper part of the cart 1 in conjunction with the vertical movement of the loading platform 31. This reduces the gap / space between the loading platform 31 and the cart 1 that occurs when the lifting device 4 moves vertically, and blocks the path for structures to enter the inside of the lifting device 4.

[0034] As described above, the lifting device 4 mounted on the automated guided vehicle 10 of this embodiment performs lifting and lowering operations by moving the first cam follower 22 located below the link mechanism 28. Therefore, the drive mechanism 29 that moves the first cam follower 22 can be positioned below the lifting device 4 and offset from directly below the link mechanism 28. This structure, along with the cutout hole in the carriage 1, allows the actuator (the motor in this invention) to be positioned below the device, making it possible to make the device flatter than the lifting device of Patent Document 2, in which the drive mechanism is located at the swing fulcrum (the position of the swing shaft member 16 in this application). The structure of Patent Document 1, in which the screw shaft 14 is positioned parallel to the running surface of the carriage 1 without using a vertical linear motion device such as a worm jack, reduces height restrictions due to the shaft stroke, allowing for a longer stroke of the device.

[0035] Due to the relationship between the lifting unit main body 30 and the load receiving platform 31, if a structure intrudes between the load receiving platform 31 and the cart 1 while the lifting device is operating without handling a load, the load acting on the structure can be limited to the load receiving platform 31. Furthermore, the structure consisting of the cart 1, load receiving platform 31, cover 32, and hinge 33 physically blocks the intrusion route for areas that cannot be covered by the relationship between the lifting unit main body 30 and the load receiving platform 31 alone, thereby preventing the intrusion of structures.

[0036] Thus, by locating the drive mechanism of the lifting device at a low position, a long-stroke and flat lifting device can be realized, and by installing this lifting device, an automatic guided vehicle can be made to have a low floor, and an automatic guided vehicle can be provided that is suitable for loads on low path lines and can handle the path lines of a wide variety of loads with the same vehicle.In the above embodiment, the screw shaft 14 and the moving member 15 are mated with each other using a male screw and a female screw, but a ball screw may also be used here.

[0037] In addition to this, it is possible to select and discard the configurations given in the above embodiments, or to change them to other configurations as appropriate, without departing from the spirit of the present invention.

[0038] REFERENCE SIGNS LIST 1 Carriage 2 Drive wheel 4 Lifting device 10 Automatic guided vehicle 11 Motor (drive source) 12 Device base 13 Device lifting unit 14 Screw shaft 15 Moving member 19 First link arm 19a First end of first link arm 19b Second end of first link arm 20 Second link arm 20a First end of second link arm 20b Second end of second link arm 21 Second cam follower 22 First cam follower 23 Auxiliary cam follower 28 Link mechanism 29 Drive mechanism 30 Lifting unit main body 31 Load receiving platform 32 Cover 33 Hinge 41 Cylindrical wall 51 Fixed shaft portion of first cam follower 53 Outer ring of first cam follower G1 Cam follower guide surface G2 Cam follower guide groove S Load placement area

Claims

1. A device comprising: a carriage equipped with drive wheels and configured to be freely movable; and a lifting device provided on the carriage so as to be able to rise and fall; the lifting device having a load placement section for placing a load, and an equipment lifting section having a cam follower guide surface on its underside parallel to the running surface of the carriage; and an equipment base section fixed at a fixed position below the equipment lifting section, and having a cam follower guide groove extending in a direction parallel to the running surface of the carriage. a link mechanism having first and second link arms connected to each other in an X-shape by pin joints at intermediate portions and rotatably connected to each other around the joint portion, a first end portion of the first link arm being rotatably supported at a fixed position on the device lifting section, a first cam follower being provided at a second end portion of the first link arm and engaging with the cam follower guide groove, a first end portion of the second link arm being rotatably supported at a fixed position on the device base section, a second cam follower being provided at a second end portion of the second link arm and engaging with the cam follower guide surface; and a drive mechanism for moving the first cam follower in the parallel direction, the drive mechanism comprising: a screw shaft provided on the device base section and extending in the parallel direction; a moving member that is screwed onto the screw shaft, supported so as not to be rotatable relative to the screw shaft, and provided with the first cam follower; and a drive source that rotationally drives the screw shaft.

2. An automated guided vehicle as described in claim 1, wherein an auxiliary cam follower is provided on the moving member at a distance from the first cam follower in the traveling direction of the carriage and engaged with the cam follower guide groove.

3. An automated guided vehicle according to claim 1 or 2, wherein the movable member is arranged to extend in the width direction of the carriage, and the link mechanism is provided on each of the left and right ends of the movable member.

4. The unmanned transport vehicle according to claim 3, wherein the first and second lifting devices are provided spaced apart in the traveling direction of the carriage.

5. An unmanned transport vehicle as described in claim 1 or 2, wherein the equipment lifting section comprises a lifting section main body with the second cam follower engaged on its underside, a load receiving platform placed on the lifting section main body, and a cover rotatably connected to one end of the load receiving platform in the front or rear of the traveling direction of the carriage, the lower end of which is in slidable contact with the upper surface of the carriage.

6. An automated guided vehicle as described in claim 1 or 2, wherein the first cam follower comprises an outer ring and a fixed shaft portion disposed in the cam follower guide groove, the fixed shaft portion is fixed to the movable member, the movable member is provided with a cylindrical wall portion surrounding the fixed shaft portion, and the first link arm is attached so as to be freely rotatable around the cylindrical wall portion.

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