Travel device

Abstract

The present invention relates to a traveling device, and an object thereof is to provide a new type of traveling device that does not cause enlargement and is expected to improve operation performance and work efficiency. The traveling device (100) can move forward and backward relative to the object to be carried (300), and has a fork (1) whose one end (1A) is supported by a main body (6) and the other end (1B) protrudes from the main body, and the object to be carried is loaded by inserting the other end into the object to be carried; a rotating body (3) which is mounted on the other end of the fork through a connecting mechanism and is used for changing the relative position with the fork; an auxiliary rotating body (4) which is arranged on at least one side closer to the insertion and extraction direction of the fork than the rotating body and can be in a position lower than the rotating body by lowering the fork; a drop detection device (17) which is arranged on at least one side closer to the insertion and extraction direction of the fork than the auxiliary rotating body and detects a drop (303) on the object to be carried, and when a drop is detected, the fork is lowered.

Description

Technical Field

[0001] The present invention relates to a traveling device. Background Art

[0002] Goods in factories and warehouses are often stored in a state of being placed on pallets as objects to be carried. Pallets are made of wood, resin, or metal and are lifted and carried by a manual fork lift (hereinafter referred to as a pallet truck) of a self-propelled or manually operated traveling device. Therefore, a socket is formed horizontally below the pallet for the insertion or extraction of the claws of the manual fork lift, that is, the forks. Structurally, since the upper beam portion of the socket protrudes upward from the lower surface of the pallet, a drop is formed. Therefore, in order to lift the pallet or the like, it is necessary to insert the forks into the socket across this drop. In order to insert the forks into the socket of the pallet, the rotating body that supports the front end of the forks at the front end of the forks must cross the drop, so this rotating body becomes an obstacle to the fork insertion operation. In addition, in the case of an empty pallet without loaded goods or a pallet loaded with light goods, since the pallet becomes an obstacle to the extraction and insertion operation of the forks, the pallet itself moves, reducing the operation performance and work efficiency. In response to this, the prior art, for example, Patent Document 1 (JP-A-2005-29082) proposes a solution that attempts to provide one or more wheels as rotating bodies at the front end and the rear end of the forks, or provide auxiliary wheels between the front and rear wheels that can extend below the plane connecting the front and rear wheels to reduce the resistance when the forks are extracted and inserted.

[0003] In the case of the conventional auxiliary wheel type, in order to change the relative positional relationship between the rotating body and the auxiliary wheels, the lifting function of the forks and the movement of the auxiliary wheels each require a separate mechanism or drive source, which is also the main reason for the enlargement of the equipment. Summary of the Invention

[0004] In view of the above problems, the present invention provides a new traveling device that does not cause the enlargement of the equipment, and aims to improve the operation performance and work efficiency.

[0005] The traveling device provided by the present invention can move forward and backward relative to the object to be carried, and is characterized in that it has a fork, one end of the fork is supported by the main body, and the other end protrudes from the main body, and the object to be carried is loaded by inserting the other end into the object to be carried; a rotating body, which is installed at the other end of the fork through a connecting mechanism and is used to change the relative position with the fork; an auxiliary rotating body, which is arranged in at least one of the fork insertion direction and the fork extraction direction closer to the rotating body, and can be in a position relatively lower than the rotating body by lowering the fork; a drop detection device, which is arranged in at least one of the fork insertion direction and the fork extraction direction closer to the auxiliary rotating body, and is used to detect the drop provided on the object to be carried, and when the drop detection device detects the drop, the fork is lowered.

[0006] According to the present invention, a rotating body and an auxiliary rotating body are configured. The rotating body is arranged on the fork, and the auxiliary rotating body is arranged in at least one of the fork insertion direction and the fork extraction direction closer to the rotating body, and can be in a position relatively lower than the rotating body by lowering the fork. A drop detection device is configured. The drop detection device is arranged in at least one of the insertion direction of the auxiliary rotating body or the extraction direction of the fork, and is used to detect the drop provided on the object to be carried. When the drop detection device detects the drop, the fork is lowered. Therefore, compared with the existing structure, the load applied to the drop when the rotating body passes through the drop can be reduced. Therefore, the present invention can provide a new traveling device that does not cause the equipment to be enlarged and can improve the operation performance and work efficiency. Brief Description of the Drawings

[0007] Figure 1 is a perspective view of a form of the traveling device related to the present invention and a pallet.

[0008] Figure 2 is a side view of the structure of the traveling device.

[0009] Figure 3 is a schematic diagram of the lifting device of the fork equipped with the traveling device.

[0010] Figure 4 is a schematic diagram of the link mechanism that makes the driven wheel displace with the lifting of the fork.

[0011] Figure 5 is an enlarged view of the structure behind the fork.

[0012] Figure 6 (a)-(c) are schematic diagrams of the positional relationship between the driven wheel and the auxiliary wheel with the lifting of the fork.

[0013] Figure 7It is a schematic diagram of the structure of the first embodiment in which the auxiliary wheel is arranged in front of the driven wheel. Among them, (a) shows the state where the driven wheel touches the ground, and (b) shows the state where the driven wheel is at a position higher than the auxiliary wheel.

[0014] Figure 8 It is a schematic diagram of the structure of the second embodiment in which the auxiliary wheel is arranged behind the driven wheel. Among them, (a) shows the state where the driven wheel touches the ground, and (b) shows the state where the driven wheel is at a position higher than the auxiliary wheel.

[0015] Figure 9 It is a schematic diagram of the structure of the third embodiment in which the auxiliary wheels are respectively arranged in front of and behind the driven wheel. Among them, (a) shows the state where the driven wheel touches the ground, and (b) shows the state where the driven wheel is at a position higher than the two auxiliary wheels.

[0016] Figure 10 It is a side view of the initial insertion state where the forklift forks are inserted into the pallet in the first embodiment.

[0017] Figure 11 It is that the auxiliary wheel 5 moves from Figure 1 the state to the state of moving upward above the drop.

[0018] Figure 12 It is a schematic diagram of the state where the driven wheel moves upward and the auxiliary wheel contacts the upper surface of the drop as the forklift forks descend.

[0019] Figure 13 It is a schematic diagram of the state where the forklift forks move in the state where the auxiliary wheel contacts the upper surface of the drop.

[0020] Figure 14 It is a schematic diagram of the state where the driven wheel descends and contacts the upper surface of the drop as the forklift forks rise.

[0021] Figure 15 It is a schematic diagram of the state where the forklift forks move in the state where the driven wheel contacts the upper surface of the drop.

[0022] Figure 16 It is a schematic diagram of the state where the driven wheel crosses the drop.

[0023] Figure 17 It is a schematic diagram of the initial state of withdrawing the forklift forks from the pallet.

[0024] Figure 18 It is a schematic diagram of the state where the driven wheel rises and the auxiliary wheel is set as the forklift forks descend.

[0025] Figure 19 It is a schematic diagram of the state where the driven wheel is above the drop during withdrawal.

[0026] Figure 20 It is to make the forklift forks from Figure 19Schematic diagram of the state where the state rises.

[0027] Figure 21 It is a schematic diagram of the state where the fork is withdrawn in the state where the driven wheel contacts the upper surface of the drop.

[0028] Figure 22 It is a schematic diagram of the state where the fork is withdrawn from the tray.

[0029] Figure 23 It is a side view of the initial insertion state where the fork is inserted into the tray in the second embodiment.

[0030] Figure 24 It is a schematic diagram of the state where as the fork descends, the driven wheel moves upward and the auxiliary wheel touches the ground.

[0031] Figure 25 It is from Figure 24 Schematic diagram of the state where the fork is inserted starting from the state, and the driven wheel contacts the upper surface of the drop.

[0032] Figure 26 It is a schematic diagram of the state where the fork rises and the auxiliary wheel rises.

[0033] Figure 27 It is a schematic diagram of the state where the driven wheel contacts the upper surface of the drop in the state where the auxiliary wheel rises, and the fork moves in the insertion direction in the state where the auxiliary wheel rises.

[0034] Figure 28 It is a schematic diagram of the state where the driven wheel and the auxiliary wheel cross the drop.

[0035] Figure 29 It is a schematic diagram of the initial state of withdrawing the fork from the tray.

[0036] Figure 30 It is a schematic diagram of the state where the auxiliary wheel is above the drop when the fork is withdrawn.

[0037] Figure 31 It is a schematic diagram of the state where the auxiliary wheel contacts the upper surface of the drop when the fork is withdrawn.

[0038] Figure 32 It is a schematic diagram of the state where the fork descends, the driven wheel rises, and the auxiliary wheel contacts the upper surface of the drop when the fork is withdrawn.

[0039] Figure 33 It is a schematic diagram of the state where the driven wheel contacts the upper surface of the drop when the fork is withdrawn.

[0040] Figure 34 It is a schematic diagram of the state where the auxiliary wheel passes through the drop.

[0041] Figure 35 It is a schematic diagram of the state where the fork is withdrawn from the tray.

[0042] Figure 36 It is a side view of the initial insertion state where the fork is inserted into the pallet in the third embodiment equipped with two auxiliary wheels.

[0043] Figure 37 It is the state where the auxiliary wheel moves from Figure 36 to above the drop. It is a side view of this state.

[0044] Figure 38 It is a schematic diagram of the state where, as the fork descends, the driven wheel moves upward and the other auxiliary wheel is located on the upper surface of the drop.

[0045] Figure 39 It is a schematic diagram of the state where the fork moves in the state where one of the auxiliary wheels contacts the upper surface of the drop.

[0046] Figure 40 It is a schematic diagram of the state where, as the fork ascends, the driven wheel descends and contacts the upper surface of the drop.

[0047] Figure 41 It is a schematic diagram of the state where the fork moves in the insertion direction in the state where the driven wheel contacts the upper surface of the drop.

[0048] Figure 42 It is a schematic diagram of the state where the driven wheel and multiple auxiliary wheels straddle the drop.

[0049] Figure 43 It is a schematic diagram of the initial state of withdrawing the fork from the pallet.

[0050] Figure 44 It is a schematic diagram of the state where the other auxiliary wheel is located above the drop when withdrawing the fork.

[0051] Figure 45 It is a schematic diagram of the state where, when withdrawing the fork, the fork descends, the driven wheel ascends, and the other auxiliary wheel contacts the upper surface of the drop.

[0052] Figure 46 It is a schematic diagram of the state where, when withdrawing the fork, the driven wheel is above the drop in the state where the driven wheel contacts the upper surface of the drop.

[0053] Figure 47 It is a schematic diagram of the state where the fork ascends and the driven wheel descends and contacts the upper surface of the drop.

[0054] Figure 48 It is a schematic diagram of the state where the fork is moved in the withdrawal direction in the state where the driven wheel contacts the upper surface of the drop.

[0055] Figure 49 It is a schematic diagram of the state of withdrawing the fork from the pallet.

[0056] Figure 50It is a structural module diagram of a control system for a traveling device.

[0057] Figure 51 It is a flowchart of the forklift insertion process in the first and third embodiments.

[0058] Figure 52 It is a flowchart of the forklift extraction process in the first embodiment.

[0059] Figure 53 It is a flowchart of the forklift insertion process in the second embodiment.

[0060] Figure 54 It is a flowchart of the forklift removal process in the second and third embodiments.

[0061] Figure 55 It is a structural module diagram of a control system for an automatic handling system of a transporting traveling device.

[0062] Figure 56 It is a flowchart of the operation of the automatic handling system.

[0063] Figure 57 (a) to (c) thereof are schematic diagrams of a wheel structure for facilitating the tray of a conventional manual hand forklift to cross a drop.

[0064] Figure 58 It is a comparison result table of the wheel structures of the conventional wheel structure and the wheel structure of the present embodiment. Detailed implementation mode

[0065] The traveling device related to the present invention includes a forklift that is lifted and lowered by a lifting mechanism equipped with a motor, etc., a wheel as a rotating body installed at least on either the front or the rear of the forklift, and an auxiliary rotating body installed at least on either the front or the rear of the wheel. It is configured such that by lowering the forklift, the auxiliary rotating body can be in a position lower than the rotating body of the forklift. In order to insert the forklift into the tray, the traveling device is provided with a drop detection device, which is a device for detecting the drop of the tray in front of the rotation center axis of the auxiliary rotating body. The traveling device controls the lifting position of the forklift according to the detection result of the drop detection device.

[0066] In the past, when inserting or extracting the forklift equipped on the traveling device on a double-sided loading type tray that can be loaded on either the upper or lower side, the traveling device needed to move with an impact to make the wheels and the like rotate to cross the drop existing on the lower surface of the tray, and the forklift could not be inserted or extracted without a load. In addition, when there is no cargo loaded on the tray or when light cargo is loaded, the wheel applies a force greater than or equal to the static friction force in the horizontal direction to the drop on the lower surface of the tray, resulting in the movement of the tray, and it is difficult to insert the forklift into the tray surely. There is still room for improvement in terms of work efficiency and operation performance.

[0067] In this regard, by adopting the configuration of the present embodiment, it is not necessary to add complex mechanisms and actuators. Just by the operation of the fork lifting mechanism, the forks can be inserted into or withdrawn from the pallet without load. Even when the traveling device moves by itself in the factory under autonomous driving to carry the pallet, this configuration can effectively function to ensure that the traveling device can indeed perform autonomous traveling and carrying.

[0068] The embodiments of the traveling device of the present invention will be described below with reference to the accompanying drawings in sequence. In the embodiments, the same reference numerals are given to the parts having the same functions and the same structures, and repeated descriptions are appropriately omitted. There are also cases where some parts are omitted or simplified in the drawings to help understand some of the configurations.

[0069] Figure 1 (a), Figure 1 (b) is a perspective view of an example of a traveling device according to the present invention, that is, a pallet truck 100 and a pallet 300 carried by the pallet truck 100. Figure 2 It is a side view of the pallet truck 100. Pallet trucks are available in both autonomous and manually operated types. The pallet truck 10 involved in the present embodiment is an autonomous traveling pallet truck.

[0070] The pallet truck 100 has a pair of forks 1 that are parallel to each other and can be lifted and lowered for loading the pallet 300 as the object to be carried, drive wheels 2 as driving rotating bodies provided on the main body 6, and follower wheels 3 as rotating bodies respectively arranged at the front ends 1B of the forks 1. One end of the fork 1, that is, the rear end 1A, is supported inside the main body 6, and the other end, that is, the front end 1B, is formed in an arm shape protruding from the main body 6. Since the pallet truck 100 can move forward and backward relative to the pallet 300, the forks provided therein can also move forward and backward relative to the pallet 300. In the present embodiment, the arrow R1 indicates the insertion direction of the forks, and the arrow R2 indicates the withdrawal direction of the forks.

[0071] Inside the main body 6, a drive motor 22 as a drive source for driving the drive wheels 2, a lifting mechanism 20 for lifting the forks 1, a lifting motor 23 as a drive source for starting the lifting mechanism to lift the forks 1, a measuring device 24 for measuring the lifting amount of the forks 1, a storage battery 25 as a power supply unit, a control unit 26 which is a control device of the pallet truck 100 for controlling each motor and sensor, a map database memory 27 for storing map data necessary for autonomous traveling, and a path calculation unit, that is, a calculation device 28 for calculating the traveling path and traveling distance to a specified destination are built in. In addition, a pallet position detection device 7 such as a detection camera is provided in front of the main body 6 for detecting the position of the pallet. The drive wheels 2 are installed below the main body 6, and the front end 1B of the forks 1 is supported by the main body 6 and the lifting mechanism 20.

[0072] The pallet 300 is, for example, a double-sided loadable wooden pallet, and insertion holes 301 for inserting or withdrawing the forklift 1 are formed around the lower part thereof. A plurality of beams are arranged at the lower part of the insertion holes 301, forming a drop 303 under the pallet.

[0073] The lifting mechanism 20 is composed of a ball screw shaft 201 and a link mechanism 202 as shown in Figure 3 , Figure 4 . The ball screw shaft 201 is vertically arranged rotatably in the main body 6, and is mounted at the front end 1B of the forklift 1 inserted into the main body 6, and is driven by the forward and reverse rotation of the lifting motor 23. The link mechanism is composed of four links 203, 204, 205, and 206. The link 203 is a rod-shaped link, and joints are provided at both ends thereof. One end of the link 203 is pivotally connected to the main body 6 such as the fixing plate 207 on the ball screw shaft 201, and is connected to a position that does not change in height as the forklift 1 moves up and down. The other end of the link 203 is pivotally connected to the link 204. Three joints are provided in the plate-shaped link 204. One is connected to the link 203, one is connected to the link 205, and the other is connected to the other end 1B of the forklift 1 through the shaft 208.

[0074] The link 205 is a rod-shaped link extending longitudinally of the forklift 1, and joints are provided at both ends thereof. One end is pivotally connected to the link 204, and the other end is pivotally connected to the link 206. Three joints are provided in the plate-shaped pivot 206. One is connected to the link 205, one is connected to the driven wheel 3, and the other is connected to the front end 1A of the forklift 1 through the shaft 209. The driven wheel 3 is rotatably supported by the link 206 through the shaft 15.

[0075] The above link mechanism 209 raises and lowers the forklift 1 through the drive of the lifting motor 23, changing the relative positions of the forklift 1 and the driven wheel 3. When the forklift 1 rises, the link 204 rotates in the direction of pushing the link 204 forward with the shaft 208 (joint) connected to the forklift as the center. Thus, the link 206 connected to the link 205 rotates in the direction of the driven wheel 3 descending with the shaft 209 (joint) connected to the forklift 1 as the center. That is, when the forklift 1 rises, the driven wheel 3 moves relatively downward. When the forklift 1 descends, the link 204 rotates in the direction of pulling the link 205 backward with the shaft 208 connected to the forklift 1 as the center. Accordingly, the link 206 connected to the link 205 rotates in the direction of the driven wheel 3 rising with the shaft 209 connected to the forklift 1 as the center. That is, when the forklift 1 descends, the driven wheel 3 moves relatively upward.

[0076] As shown in Figure 1 , Figure 2 , Figure 5As shown in the figure, the pallet truck 100 has auxiliary wheels 4 and 5 as auxiliary rotating bodies. The auxiliary wheel 4 is provided at a position in front of the driven wheel 3 of the fork 1 and can be in a position lower than the driven wheel 3 as the fork 1 descends. The auxiliary wheel 5 is provided at a position behind the driven wheel and can be in a position lower than the driven wheel 3 as the fork 1 descends. The auxiliary wheel 4 is rotatably supported by the fork 1 through the shaft 16. The auxiliary wheel 5 is rotatably supported by the link 205 through the shaft 12.

[0077] As shown in Figure 5 the figure, the fork 1 is provided with a drop detection device 17 and a drop detection device 18 for detecting the drop. The drop detection device 17 is installed at a position in front of the shaft 16 which is the rotation center of the auxiliary wheel 4. The drop detection device 18 is installed at a position behind the shaft 12 which is the rotation center of the auxiliary wheel 5. That is, the drop detection device 17 is arranged closer to the fork insertion direction R1 than the auxiliary wheel 4, and the drop detection device 18 is arranged closer to the fork extraction direction R2 than the auxiliary wheel 5 to detect the drop 303.

[0078] In this embodiment, the auxiliary wheel 4 and the auxiliary wheel 5 are provided. However, as long as at least one of the auxiliary wheels is provided, the mechanism as an auxiliary wheel can be realized. The drop detection devices 17 and 18 are composed of reflective optical sensors and detect the distance or position of the drop to the pallet described later.

[0079] When only the auxiliary wheel 4 which is provided in front of the driven wheel 3 of the fork 1 and can be in a position lower than the driven wheel 3 as the fork 1 descends is provided, the drop detection device 18 is installed at a position behind the shaft 16 of the driven wheel 3. When only the auxiliary wheel 5 which is provided behind the driven wheel 3 and can be in a position lower than the driven wheel 3 as the fork 1 descends is provided, the drop detection device 18 is installed at a position in front of the shaft 16 of the driven wheel 3.

[0080] Next, Figure 6 the positional relationship between the driven wheel 3 and the auxiliary wheel 4 caused by the lifting of the fork 1 is shown in (a) to (c) of Figure 6 This is an example with only the auxiliary wheel 4. When the fork 1 descends from the Figure 6 (a) position to Figure 6 (b) and 6(c) in sequence, as the fork 1 descends, the auxiliary wheel 4 fixed on the fork 1 descends, and the driven wheel 3 moves relatively upward. Therefore, by lowering the fork 1, the positional relationship between the driven wheel 3 and the auxiliary wheel 4 changes relatively.

[0081] Next, the actions of the driven wheel 3 and the auxiliary wheel 4 accompanying the lifting action of the fork 1 will be described.

[0082] Figure 7(a) and (b) show the case where the auxiliary wheel 4 is closer to the front end 1B of the forklift 1 than the driven wheel 3. Figure 8 (a) and (b) show the case where the auxiliary wheel 5 is closer to the front end 1B of the forklift 1 than the driven wheel 3. Figure 9 (a) and (b) show the case where the auxiliary wheels 4 and 5 are respectively provided closer to both the front end side 1B and the rear end 1A than the driven wheel 3.

[0083] Figure 7 In (a), it is a schematic view when the pallet truck 100 makes the driven wheel 3 contact the ground and perform normal driving, etc., and in (b), it is a schematic view when the forklift 1 is lowered to a position where the driven wheel 3 is higher than the auxiliary wheel 4. The forklift 1 is lifted and lowered by the ball screw shaft 201 rotated by the lifting motor 23 described above. The driven wheel 3 is hinged to the forklift 1 through the linkages 203 - 206, and the relative position with the forklift 1 changes as the forklift 1 is lifted and lowered. The linkages 203 - 206 are configured such that when the forklift 1 is lowered to Figure 7 the lowest point shown in (b), the driven wheel 3 is in a position higher than the auxiliary wheel 4.

[0084] Figure 8 In (a), it is a schematic view when the pallet truck 100 makes the driven wheel 3 contact the ground for normal driving, and in (b), it is a schematic view when the forklift 1 is lowered to a position where the driven wheel 3 is higher than the auxiliary wheel 5. The forklift 1 is lifted and lowered by the ball screw shaft 201 rotated by the lifting motor 23 described above. The driven wheel 3 is hinged to the forklift 1 through the linkages 203 - 206, and the relative position with the forklift 1 changes as the forklift 1 is lifted and lowered. The linkages 203 - 206 are configured such that when the forklift 1 is lowered to Figure 7 the lowest point shown in (b), the driven wheel 3 is in a position higher than the auxiliary wheel 4.

[0085] Figure 9 In (a), it is a schematic view when the pallet truck 100 makes the driven wheel 3 contact the ground for normal driving, and in (b), it is a schematic view when the forklift 1 is lowered to a position where the driven wheel 3 is higher than the auxiliary wheels 4 and 5. The forklift 1 is lifted and lowered by the ball screw shaft 201 rotated by the lifting motor 23 described above. The driven wheel 3 is hinged to the forklift 1 through the linkages 203 - 206 and changes its relative position with the forklift 1 as the forklift 1 is lifted and lowered. The linkages 203 - 206 are configured such that when the forklift 1 is lowered to Figure 7 the lowest point shown in (b), the driven wheel 3 is in a position higher than the auxiliary wheels 4 and 5.

[0086] The following describes the operation of the pallet truck 100 automatically crossing the height difference 303 on the lower surface of the pallet.

[0087] (First Embodiment)

[0088] Figures 10 to 16 It shows the operation of inserting the pallet 300 (the fork insertion process of the first embodiment) when the auxiliary wheel 4 that can be positioned below the driven wheel 3 by lowering the forks 1 is arranged closer to the front end 1B of the forks 1 than the driven wheel 3. When the pallet truck 100 inserts the forks 1 into the pallet 300, the pallet detection device 7 installed in front of the main body 1 for detecting the pallet position detects the position of the pallet 300 or the position of the fork insertion hole 301 located on the side of the pallet 300, calculates the moving amount of the pallet truck 100 based on the rotation angle of the drive wheel 2, and approaches the pallet while performing travel control. The automatic travel control and the lifting control of the forks 1 will be described later.

[0089] Figure 10 It shows the state where the drop detection device 17 provided in front of the auxiliary wheel 4 is located on the drop 303. Figure 10 In the state shown, the drop detection device 17 is mounted on the forks 1 with the detection surface facing downwards. When the drop detection device 17 detects the drop 303 on the lower surface of the pallet, the forks 1 are lifted and lowered until the auxiliary wheel 4 is positioned above the upper surface 303a of the drop.

[0090] After the drop detection device 17 detects the drop 303 and the forks 1 are lifted and lowered so that the auxiliary wheel 4 is positioned above the upper surface 303a of the drop, the pallet truck 100 drives the drive wheel 2 so that the drive wheel 2 moves a distance equivalent to the distance from the drop detection device 17 to the center of rotation of the axis of the auxiliary wheel 4 (the center of rotation of the shaft 16). Then, as Figure 11 shown, the forks 1 are inserted into the insertion port 301 until the auxiliary wheel 4 reaches the drop 303.

[0091] After inserting the forks 1 until the auxiliary wheel 4 is located on the drop 303, the forks 1 are lowered so that the auxiliary wheel 4 contacts the upper surface 303a of the drop. Further, from this state, as Figure 12 shown, the forks 1 are depressed until the driven wheel 3 is positioned higher than the auxiliary wheel 4. In the state where the auxiliary wheel 4 contacts the upper surface 303a of the drop and the driven wheel 3 is positioned higher than the auxiliary wheel 4, the pallet truck 100 drives the drive wheel 2 to rotate so that the drive wheel 2 moves a distance equivalent to the distance from the center of rotation of the axis of the auxiliary wheel 4 (the center of rotation of the shaft 16) to the center of rotation of the axis of the driven wheel 3 (the center of rotation of the shaft 15), and as Figure 13 shown, the forks 1 are inserted until the driven wheel 3 reaches the upper surface 303a of the drop.

[0092] After inserting the forks 1 until the driven wheel 3 reaches the upper surface 303a of the drop, the pallet truck 100 raises the forks 1, as Figure 14 shown, so that the driven wheel 3 contacts the upper surface 303a of the drop. As Figure 15As shown, the pallet truck 100 inserts the fork 1 with the driven wheel 3 in contact with the upper surface 303a of the drop, as Figure 16 shown, the driven wheel 3 is lowered from the drop 303 below the pallet. Further, when the drop detection device 17 detects the next drop, it operates in the same manner as described above and crosses the drop 303. Before the positional relationship between the fork 1 and the pallet 300 reaches a state where the pallet truck 100 can lift and carry the pallet 300 in a stable state, the pallet truck 100 operates in the same manner as described above, and by crossing the drop 303, inserts the fork 1 into the pallet.

[0093] Figures 17 to 22 Shows the operation of pulling out the fork 1 from the pallet 300 when the auxiliary wheel 4 is installed in front of the driven wheel 3 of the fork 1 (the pulling-out operation of the first embodiment).

[0094] Figure 17 Shows the state where the drop detection device 18 for detecting the drop 303 behind the rotation center of the rotation axis of the driven wheel 3 (the rotation center of the shaft 15) reaches the upper surface 303a of the drop. In Figure 17 the state shown, the drop detection device 18 is installed on the fork 1 with the detection surface facing downward. When the drop detection device 18 detects the drop 303, the pallet truck 100 is as Figure 18 shown, lowers the fork 1 so that the auxiliary wheel 4 touches the ground, and the driven wheel 3 is at a position higher than the upper surface 303a of the drop. After lowering the auxiliary wheel 4 so that the auxiliary wheel 3 touches the ground and the driven wheel 3 is at a position higher than the upper surface 303a of the drop, the pallet truck 100 drives the drive wheel 2 to rotate, and moves the drive wheel 2 by a distance equivalent to the distance from the drop detection device 18 to the rotation center of the rotation axis of the driven wheel 3 (the rotation center of the shaft 15), and pulls out the fork 1 until Figure 19 shown, the driven wheel 3 reaches the upper surface 303a of the drop.

[0095] After pulling out the fork 1 until the driven wheel 3 reaches the upper surface 303a of the drop, the pallet truck 100 is as Figure 20 shown, raises the fork 1 so that the driven wheel 3 touches the upper surface 303a of the drop. After raising the fork 1 so that the driven wheel 3 touches the upper surface 303a of the drop, the pallet truck 100 is as Figure 21 shown, in the state where the driven wheel 3 touches the upper surface 303a of the drop, pulls out the fork 1, as Figure 22 shown, lowers the driven wheel 3 from the upper surface of the drop. Further, when the drop detection device 18 detects the next drop 303, the pallet truck 100 operates in the same manner as described above and crosses the drop 303. Before completely pulling out the fork 1 from the pallet 300, it operates in the same manner as described above, and pulls out the fork 1 from the pallet by crossing the drop.

[0096] (Second Embodiment)

[0097] Figures 23 to 28 It shows the operation of inserting the pallet 300 when the auxiliary wheel 5, which can be positioned below the driven wheel 3 by lowering the fork 1, is installed behind the driven wheel 3 of the fork 1 (fork insertion process of the second embodiment).

[0098] Figure 23 It shows the state where the drop detection device 17 provided in front of the center of the rotation axis of the driven wheel 3 (rotation center of the shaft 15) is located above the drop 303 of the pallet 300. Figure 23 Among them, the drop detection device 17 is installed on the fork 1 with the detection surface facing downward.

[0099] When the drop detection device 17 detects the drop 303 below the pallet, as Figure 24 shown, the auxiliary wheel 5 of the pallet truck 100 touches the ground, and the driven wheel 3 is positioned above the upper surface 303a of the drop.

[0100] After lowering the fork 1 to make the auxiliary wheel 5 touch the ground and the driven wheel 3 be positioned above the upper surface 303a of the drop, the pallet truck 100 drives the drive motor 22 to rotate the drive wheel 2 and moves a distance equivalent to the distance from the drop detection device 17 to the center of the rotation axis of the driven wheel 3 until, as Figure 25 shown, the driven wheel 3 reaches above the drop 303 on the lower surface of the pallet and inserts the fork 1.

[0101] After the driven wheel 3 reaches the drop 303 on the lower surface of the pallet and inserts the fork 1, the pallet truck 100, as Figure 26 shown, raises the fork 1 to make the driven wheel 3 contact the upper surface 303a of the drop below the pallet.

[0102] After raising the fork 1 to make the driven wheel 3 contact the driven wheel a, as Figure 27 shown, the pallet truck 100 inserts the fork 1 with the driven wheel 3 contacting the upper surface 303a of the drop, and as Figure 28 shown, lowers the driven wheel 3 from the upper surface 303a of the drop. Furthermore, when the drop detection device 17 detects the next drop 303, the pallet truck 100 performs the same operation as above to cross the drop 303. The pallet truck 100 performs the same operation as above before the positional relationship between the fork 1 and the pallet 300 becomes such that the pallet truck 100 can lift and carry the pallet 300 in a stable state, and inserts the fork 1 into the pallet 300 by crossing the drop 303.

[0103] Figures 29 to 35 It shows the operation of extracting from the pallet 300 when the auxiliary wheel 5, which can be positioned below the driven wheel 3 by lowering the fork 1, is installed at the rear position of the driven wheel 3 of the fork 1 (extracting operation of the second embodiment).

[0104] Figure 29It shows the state where the drop detection device 18, which is located behind the center of the rotation axis of the auxiliary wheel 5, is on the drop 303 of the tray 300. In Figure 29 , the drop detection device 18 is mounted on the forklift 1 with the detection surface facing downward. When the drop detection device 18 detects the drop 303, the pallet truck 100 raises and lowers the forklift 1 so that the auxiliary wheel 5 is in a position higher than the upper surface 303a of the drop.

[0105] After the drop detection device 18 detects the drop 303 and the forklift 1 is raised and lowered so that the auxiliary wheel 5 is in a position higher than the upper surface 303a of the drop, the pallet truck 100 operates the drive motor 22 to rotate the drive wheel 2, causing the drive wheel 2 to move a distance equivalent to the distance from the drop detection device 18 to the center of the rotation axis of the auxiliary wheel 5, and withdraws the forklift 1 until, as Figure 30 shown, the auxiliary ground wheel 5 reaches the drop 303.

[0106] After withdrawing the forklift 1 until the auxiliary wheel 5 reaches the drop 303, the pallet truck 100 lowers the forklift 1 so that the auxiliary wheel 5 contacts the upper surface 303a of the drop. The pallet truck 100 further depresses the forklift 1 from this state so that, as Figure 31 shown, the driven wheel 5 is in a position higher than the auxiliary wheel.

[0107] In a state where the auxiliary wheel 5 contacts the upper surface 303a of the drop and the position of the driven wheel 3 is higher than the position of the auxiliary wheel 5, the pallet truck 100 operates the drive motor 22 to rotate the drive wheel 2, causing the drive wheel 2 to move a distance equivalent to the distance from the center of the rotation axis of the auxiliary wheel 5 (the axis of the shaft 12) to the center of the rotation axis of the driven wheel 3 (the axis of the shaft 15), and withdraws the forklift 1 until, as Figure 32 shown, the driven wheel 3 reaches the drop 303.

[0108] After withdrawing the forklift 1 until the driven wheel 3 reaches the drop 303, the pallet truck 100 raises the forklift 1 so that, as Figure 33 shown, the driven wheel 3 contacts the upper surface 303a of the drop. After raising the forklift 1 to make the driven wheel 3 contact the drop 303, the pallet truck 100, as Figure 34 shown, withdraws the forklift 1 in a state where the driven wheel 3 contacts the upper surface 303a of the drop, and, as Figure 35 shown, lowers the driven wheel 3 from the upper surface 303a of the drop. Further, when the drop detection device 18 detects the next drop 303, the pallet truck 100 operates in the same manner as above to cross the drop 303. Before completely withdrawing the forklift 1 from the pallet, the pallet truck 100 operates in the same manner as above and withdraws the forklift 1 from the pallet 300 by crossing the drop 303.

[0109] (Third Embodiment)

[0110] Figures 36 to 42It shows the operation of inserting the pallet 300 when the auxiliary wheel 4 that can be positioned relatively lower than the driven wheel 3 by lowering the forklift 1 is installed in front of the driven wheel 3 of the forklift 1, and further when the auxiliary wheel 5 that can be positioned relatively lower than the driven wheel 3 by lowering the forklift 1 is installed behind the driven wheel 3 of the forklift 1 (forklift insertion process of the third embodiment).

[0111] In Figure 36 a height difference detection device 17 provided in front of the center of the rotation axis of the auxiliary wheel 5 is mounted on the forklift 1 with the detection surface facing downward. When the height difference detection device 17 detects a height difference 303 under the pallet, the pallet truck 100 raises and lowers the forklift 1 so that the auxiliary wheel 5 is positioned higher than the upper surface 303a of the height difference.

[0112] After the height difference detection device 17 detects the height difference 303 and the forklift 1 is raised and lowered so that the auxiliary wheel 4 is positioned higher than the upper surface 303a of the height difference, the pallet truck 100 drives the drive motor 22 to rotate the drive wheel 2 and moves a distance equivalent to the distance from the height difference detection device 17 to the center of the rotation axis of the auxiliary wheel 4, and inserts the forklift 1 until, as Figure 37 shown, the auxiliary wheel 4 reaches the height difference 303.

[0113] After inserting the forklift 1 until the auxiliary wheel 4 reaches the height difference 303, the pallet truck 100 lowers the forklift 1 while making the auxiliary wheel 4 contact the upper surface 303a of the height difference, and from this state, as Figure 38 shown, depresses the driven wheel 3 until the driven wheel 3 is positioned higher than the auxiliary wheel 4.

[0114] With the auxiliary wheel 4 in contact with the upper surface 303a of the height difference and the driven wheel 3 positioned higher than the auxiliary wheel 5, the pallet truck 100 drives the drive motor 22 to rotate the drive wheel 2 and moves a distance equivalent to the distance from the center of the rotation axis of the auxiliary wheel 4 to the center of the rotation axis of the driven wheel 3, and inserts the forklift 1 until, as Figure 39 shown, the driven wheel 3 reaches the upper surface 303 of the height difference.

[0115] After inserting the forklift 1 until the driven wheel 3 reaches the upper surface 303a of the height difference, the pallet truck 100 raises the forklift 1 so that the driven wheel 3, as Figure 40 shown, contacts the upper surface 303a of the height difference. After the driven wheel 3 contacts the height difference 303 on the lower surface of the pallet, the pallet truck 100, as Figure 41 shown, inserts the forklift 1 in a state where the driven wheel 3 is in contact with the upper surface 303a of the height difference, as Figure 42As shown, the driven wheel 3 and the auxiliary wheel 5 of the forklift 1 disposed near the rear of the driven wheel 3 are lowered from the drop upper surface 303a. Further, when the drop detection device 17 detects the next drop 303, the pallet truck 100 operates in the same manner as described above and crosses the drop 303. The pallet truck 100 operates in the same manner as described above until the positional relationship between the forklift 1 and the pallet 300 reaches a state where the pallet truck 100 can lift and carry the pallet 300 in a stable state. By crossing the drop 303, the forklift 1 is inserted into the pallet 300.

[0116] Figures 43 to 49 Shows the operation when the forklift 1 having the auxiliary wheels 4 and 5 is withdrawn from the pallet 300 (forklift withdrawal process of the third embodiment).

[0117] Figure 43 Shows a state where the drop detection device 18 provided behind the center of the rotation axis of the auxiliary wheel 5 is located on the drop 303 of the pallet 300. In Figure 43 this case, the drop detection device 18 is mounted on the forklift 1 with its detection surface facing downward. When the drop detection device 18 detects the drop 303 below the pallet, the pallet truck 100 raises and lowers the forklift 1 so that the auxiliary wheel 5 is positioned higher than the drop upper surface 303a.

[0118] After the drop detection device 18 detects the drop 303 on the lower surface of the pallet and the forklift 1 is raised and lowered to raise the auxiliary wheel 5 to a position higher than the upper surface of the drop, the pallet truck 100 drives the drive motor 22 to rotate the drive wheel 2 and moves a distance equivalent to the distance from the drop detection device 18 to the center of the rotation axis of the auxiliary wheel 5 to withdraw the forklift 1 until as Figure 44 shown, the auxiliary wheel 5 reaches the drop 303.

[0119] After withdrawing the forklift 1 until the auxiliary wheel 5 reaches the drop on the lower surface of the pallet, the pallet truck 100 lowers the forklift 1 so that the auxiliary wheel 5 contacts the drop upper surface 303a, and at the same time, from this state, presses down the forklift 1 until as Figure 45 shown, the driven wheel 3 is in a position higher than the auxiliary wheel 5.

[0120] In a state where the auxiliary wheel 5 contacts the drop upper surface 303a and the position of the driven wheel 3 is higher than the position of the auxiliary wheel 5, the drive motor 22 is driven to rotate the drive wheel 2 and move a distance equivalent to the distance from the center of the rotation axis of the auxiliary wheel 5 to the center of the rotation axis of the driven wheel 3 to withdraw the forklift 1 until as Figure 46 shown, the driven wheel 3 reaches the drop upper surface 303a.

[0121] After withdrawing the forklift 1 until the driven wheel 3 reaches the drop upper surface 303a, the pallet truck 100 raises the forklift 1, as Figure 47As shown, the driven wheel 3 is brought into contact with the upper surface 303a of the step. After the forklift 1 is lifted and the driven wheel 3 is brought into contact with the upper surface 303a of the step, the pallet truck 100 is as Figure 48 shown. With the driven wheel 3 in contact with the upper surface 303a of the step, the forklift 1 is withdrawn, as Figure 49 shown. The auxiliary wheel 5 is lowered from the upper surface 303a of the step. Further, when the step detection device 18 detects the next step 303, the pallet truck 100 performs the same operation as described above to cross the step 303. Before the forklift 1 is completely withdrawn from the pallet 300, the pallet truck 100 performs the same operation as described above, and withdraws the forklift 1 from the pallet by crossing the step 303.

[0122] The control system configuration of the pallet truck 100 will be described below.

[0123] As Figure 50 shown, on the input side of the control unit 26, the pallet position detection device 7 and the step detection devices 17 and 18 are connected by signal lines. On the output side of the control unit 26, the drive motor 22 and the lift motor 23, which are control objects, are connected by signal lines. The control unit 26 includes a CPU 261 as a central arithmetic unit, a ROM 262 and a RAM 263 as storage units, and a timer 264 as a measurement unit.

[0124] The measuring device 24 for measuring the lifting amount of the forklift 1 is constituted by the control unit 26. The measuring device 24 calculates the lifting amount based on the detection information of the step detection devices 17 and 18. The map database memory 27 is used during independent travel. The path calculation unit 28, like the control unit 26, is constituted by a computer equipped with a CPU, a storage unit, a timer, etc., and is used during independent travel. In the present embodiment, the map database memory 27 and the path calculation unit 28 are separately provided from the control unit 26. Alternatively, the path calculation unit 28 can be constituted by the CPU 261 of the control unit 26, and the map database memory 27 can be constituted by the ROM 262.

[0125] Hereinafter, the control contents of the forklift insertion process (insertion operation) and the forklift withdrawal process (withdrawal operation) according to the first to third embodiments will be described. These forklift insertion process and forklift withdrawal process are mainly executed by the control unit 26, and are also executed during the forklift insertion process and forklift withdrawal process in the automatic transport system described later.

[0126] Figure 51 is a flowchart showing the control contents during the insertion operation of the first and third embodiments. That is, it shows the operation of inserting the forklift 1 into the pallet 300 when the auxiliary wheel 4 is provided in front of the driven wheel 3 and on both the front and rear sides of the driven wheel 3.

[0127] In step S201, before the drop detection device 17 detects the drop 303, the control unit 26 moves the pallet truck 100 forward in the direction of the pallet. Here, the drive motor 22 is driven to rotate the drive wheels 2. Then, when the drop detection device 17 detects the drop 303, the drive motor 22 is stopped.

[0128] After the control unit 26 detects the drop 303 by the drop detection device 17, in step S202, the drive motor 22 is driven to rotate the drive wheels 2, and the pallet truck 100 is moved forward until the auxiliary wheels 4 reach the drop 303. In step S203, the control unit 26 drives the lift motor 23 to lower the forklift 1 so that the auxiliary wheels 4 contact the upper surface 303a of the drop. At this time, the forklift 1 is lowered until the driven wheels 3 are at a position higher than the auxiliary wheels 4. The heights of the driven wheels 3 and the auxiliary wheels 4 are determined based on the detection signal of the drop detection device 17.

[0129] In step S204, the control unit 26 drives the drive motor 22 to move the pallet truck 100 forward until the driven wheels 3 reach the drop 303. In step S205, the control unit 26 raises the forklift 1 so that the driven wheels 3 contact the upper surface 303a of the drop. Here, the lift motor 23 is activated to raise the forklift 1. When the driven wheels 3 reach the height at which they contact the upper surface 303a according to the detection signal of the drop detection device 17, the lift motor 23 is stopped.

[0130] In step S206, the control unit 26 operates the drive motor 22 to move the pallet truck 100 forward until the driven wheels 3 drop to the drop 303.

[0131] In step S207, the control unit 26 confirms whether the forklift 1 has been inserted into a position where the pallet 300 can be lifted in a stable state. This can be confirmed in the following ways: for example, by determining whether the pallet position detection device 7 such as a light reflector arranged at the root of the forklift 1 detects the pallet 300, or by measuring the traveling distance after the drop 303 is initially detected. When the pallet 1 is inserted into a position where the pallet 300 can be lifted in a stable state (Yes), the drive motor 22 is stopped to stop the insertion operation, and when it is not inserted into this position (No), the operation of crossing the drop is repeated starting from S201.

[0132] Figure 52 It is a flowchart of the control content of the extraction operation of the first embodiment. That is, it shows the extraction operation of extracting the forklift from the pallet 300 when the auxiliary wheels 4 are arranged in front of the driven wheels 3.

[0133] In step S311, with the fork 1 inserted into the pallet 300, the control unit 26 operates the drive motor 22 in the direction opposite to the forward movement to reverse the pallet truck 100 in the direction of withdrawing the fork 1 from the pallet 300 until the drop detection device 18 detects the drop 303. In step S312, after the control unit 26 detects the drop by the drop detection device 18, it starts the lifting motor 23 to lower the fork 1 while bringing the auxiliary wheel 4 into contact with the ground. At this time, the fork 1 is lowered to a position where the driven wheel 3 is higher than the drop 303.

[0134] In step S313, the control unit 26 drives the drive motor 22 to reverse the pallet truck 100 until the driven wheel 3 reaches the drop 303.

[0135] In step S314, the control unit 26 starts the lifting motor 23 to raise the fork 1 so that the driven wheel 3 contacts the upper surface 303a of the drop. At this time, the fork 1 is raised to a position where the auxiliary wheel 4 is higher than the drop 303.

[0136] In step S315, the control unit 26 starts the drive motor 22 to reverse the pallet truck 100 until the driven wheel 3 descends from the drop 303.

[0137] In step S316, the control unit 26 confirms whether the fork 1 has been completely withdrawn from the pallet 300. For this, it can be confirmed by measuring the travel distance from the start of the withdrawal operation. If the fork 1 has been withdrawn from the pallet 300 (Yes), the control unit 26 ends the withdrawal operation, and if not withdrawn (No), the drop crossing operation is repeated again from step S301.

[0138] Figure 53 It is a flowchart of the control content during the insertion operation of the second embodiment. That is, it shows the fork insertion operation of the pallet 300 when the auxiliary wheel 5 is provided behind the driven wheel 3.

[0139] In step S211, before the drop detection device 17 detects the drop 303, the control unit 26 advances the pallet truck 100 toward the pallet. Here, the drive motor 22 is started to drive the drive wheel 2 to rotate. In step S212, when the drop detection device 17 detects the drop 303, the control unit 26 starts the lifting motor 23 to lower the fork 1 so that the auxiliary wheel 5 contacts the pallet placement surface (ground). At this time, the fork 1 is lowered to a position where the driven wheel 3 is higher than the drop 303.

[0140] In step S213, the control unit 26 drives the drive motor 22 to move the pallet truck 100 forward until the driven wheel 3 reaches the drop 303. In step S214, the control unit 26 activates the lifting motor 23 to lift the fork 1 so that the driven wheel 3 contacts the upper surface 303a of the drop. At this time, the lifting motor 23 is operated in the upward direction to raise the fork 1 to a position where the auxiliary wheel 5 is higher than the drop 303.

[0141] In step S215, the control unit 26 drives the drive motor 22 to move the pallet truck 100 forward until the driven wheel 3 descends onto the drop 303. In step S216, the control unit 26 confirms whether the fork 1 has been inserted into a position where the pallet 300 can be lifted in a stable state. This can be confirmed in the following ways: for example, by determining whether the pallet position detection device 7 such as a light reflector provided at the root of the fork 1 detects the pallet 300, or by measuring the travel distance after the drop 303 is initially detected. If the fork 1 has been inserted into a position where the pallet 300 can be lifted in a stable state (yes), the control unit 26 stops the operation of the drive motor 22 and ends the insertion operation. If it has not been inserted into this position (no), the operation of crossing the drop is repeated again from S201.

[0142] Figure 54 It is a flowchart of the control content of the extraction operation of the second and third embodiments. That is, when the auxiliary wheel 5 is provided behind the driven wheel 3 and when it is provided on both the front and rear sides of the driven wheel 3, it is a flowchart of the operation of inserting the fork into the pallet 300 and extracting it from the pallet 300.

[0143] In step S301, the fork 1 is in a state of being inserted into the pallet 300. In this state, before the drop detection device 18 detects the drop 303, the control unit 26 moves the pallet truck 100 backward in the direction of extracting the fork 1 from the pallet 300. That is, the drive motor 22 drives the drive wheel 2 to rotate in the opposite direction to the forward direction. In step S302, when the drop detection device 18 detects the drop 303, the control unit 26 moves the pallet truck 100 backward until the auxiliary wheel 5 reaches above the drop 303.

[0144] In step S303, the control unit 26 lowers the fork 1 so that the auxiliary wheel 5 contacts the upper surface 303a of the drop. At this time, the lifting motor 23 is driven to lower the fork 1 to a position where the height of the driven wheel 3 is higher than that of the auxiliary wheel 5. The heights of the driven wheel 3 and the auxiliary wheel 5 can be detected by the position drop detection device 18, or a preset lifting stroke can be set only for driving the lifting motor 23.

[0145] In step S304, the control unit 26 drives the drive motor 22 to reverse the pallet truck 100 until the driven wheel 3 reaches the drop 303. In steps S305 and S306, the control unit 26 raises the fork 1 and drives the lift motor 23 to bring the driven wheel 3 into contact with the upper surface 303a of the drop. At the same time, the drive motor 22 is driven to rotate to reverse the pallet truck 100 until the driven wheel 3 descends onto the drop 303.

[0146] In step S307, the control unit 26 confirms whether the fork 1 has been completely withdrawn from the pallet 300. This can be confirmed by measuring the travel distance from the start of the withdrawal operation. If the fork 1 has been withdrawn from the pallet 300 (Yes), the insertion operation is ended. If it has not been withdrawn (No), the operation of crossing the drop is repeated again from S301.

[0147] The traveling device of the fork 1 described in the above embodiment, that is, the pallet truck 100, can travel independently. Therefore, as its usage mode, it can be applied to the automatic material handling system in the warehouse. The automatic material handling system will be described below.

[0148] Figure 55 It is a schematic diagram of the system configuration of the automatic material handling system 1000. The automatic material handling system 1000 includes a pallet truck 100, a management device 200 that controls the travel route of the pallet truck 100, and an upper management device 300 that controls the management device 200. The pallet truck 100 is equipped with a pallet presence / absence detection unit 111 and a travel control unit 110. The travel control unit 110 controls the travel and stop of the pallet truck 100 by controlling the control unit 26. The upper management device 300 outputs handling request information and has a function of sending the handling request information to the management device 200. The management device 200 has a function of generating operations of the pallet truck 100 based on the transport request information received from the upper management device 300, and performing operation management and path setting. That is, the management device 200 includes a handling operation management unit 210, a path setting unit 211, a handling request receiving unit 212, a transport notification sending unit 213, a notification receiving unit 214, and an operation sending unit 215. The operation sending unit 215 is composed of a communication mechanism for sending to the pallet truck 100.

[0149] The pallet truck 100 receives the operations sent by the operation sending unit 215 of the management device 200, and autonomously travels according to the information of the operations by the travel control unit 110. The operations sent by the operation sending unit 215 are generated and managed by the handling operation management unit 210 based on the handling requests received from the upper management system 300. The autonomous travel of the pallet truck 100 is achieved by a method of controlling the travel distance and posture using an odometer and a gyro sensor, or a method of traveling while identifying its own position using the map information possessed by the pallet truck 100 and external information obtained by a laser rangefinder, a camera, etc. The travel path is set by the path setting unit 211 of the management device 200 according to, for example, two-dimensional coordinate information included in the handling request. The pallet truck 100 has a communication function of sending an operation completion notification to the notification receiving unit 214 of the management device 200 when the operation is completed. When the handling is completed, the management device 200 uses the handling notification sending unit 213 to send an end notification to the upper management device 300.

[0150] Figure 56 It is a flowchart of the actions for moving between pallets and performing operations required for the automatic handling pallet truck 100. The automatic handling system 1000 will be described according to this flowchart. The automatic handling system 1000 sends and receives information through wired or wireless communication between the pallet truck 100, the management device 200, and the upper management device 300, and at the same time, executes according to various set programs.

[0151] In step S101, the handling request receiving unit 212 of the management device 200 receives the pallet handling request sent from the upper management device 300 such as the production process management system of the factory. In step S102, the operation sending unit 215 of the management device 200 sends the pallet recovery operation generated by the handling operation management unit 210 according to the pallet handling request to the pallet truck (travel device) 100.

[0152] In step S103, the pallet truck 100 autonomously travels toward the pallet recovery position. The autonomous travel is controlled by the travel control unit 110 to control the pallet truck 100. After the pallet truck 100 reaches the pallet recovery position, in step S104, the pallet presence / absence detection unit 111 of the pallet truck confirms whether there is a pallet. As a method of confirming the presence or absence of a pallet according to the pallet presence / absence detection unit 111, for example, a method of identifying the insertion hole 301 of the pallet 300 through a depth camera, or a judgment based on the information of the pallet position detection device 7, etc.

[0153] In step S104, when there is a pallet 300 (yes), in step S105, the fork insertion process of inserting the fork 1 into the pallet 300 is executed. When it fails to confirm the presence of the pallet 300 (no), in step S114, the pallet truck 100 sends an error notification to the notification receiving unit 214 of the management device 200.

[0154] In step S105, there is a fork insertion process of inserting the fork 1 described in the first to third embodiments having the auxiliary wheels 4 or 5 described above, or having both the auxiliary wheels 4 and 5, into the pallet 300. The completion of the insertion of the fork 1 can be determined according to, for example, the detection information from the pallet position detection device 7 provided near the root of the fork 1 (the body 6), or the distance that the pallet truck 100 advances when the fork 1 is inserted into the insertion hole 301 of the pallet 300, etc.

[0155] After the fork 1 is inserted, in step S106, the pallet 300 is lifted. Here, the lifting motor 23 is started to lift the fork 1 and lift the pallet 300 from the ground.

[0156] After finishing lifting the pallet 300, in step S107, the pallet truck (traveling device) 100 sends a pallet recovery completion notice to the notification receiving unit 214 of the management device 200. Thereafter, in step S108, the job sending unit 215 of the management device 200 sends the pallet handling job generated based on the pallet handling request to the pallet truck 100 through the handling job management unit 211. In step S109, based on this pallet handling job, the pallet truck 100 travels to the pallet handling position by itself. After the pallet truck 100 reaches the pallet return position, in step S110, the pallet 300 is lowered. Here, the lifting motor 23 operates in the opposite direction to when lifting the pallet, causing the fork 1 to descend and placing the pallet 300 on the placement surface (the ground).

[0157] After that, in step S111, corresponding to the first to third embodiments, a fork extraction process of extracting the fork 1 from the pallet 300 is performed. In step S112, the pallet truck 100 sends a pallet handling completion notice to the notification receiving unit 214 of the management device 200. In step S113, a handling completion notice is sent from the handling notice sending unit 213 of the management device 200 to the upper management system 300, ending one job.

[0158] As described above, there are provided auxiliary wheels 4 and 5 that can make the driven wheel 3 installed in front of the fork 1 in a relatively low position by lowering the fork 1. The height difference detection devices 17 and 18 provided at least one of the front and rear of the rotation center axis of the auxiliary wheel detect the height difference 303 on the lower surface of the pallet 300, and the fork 1 is lowered based on the detection result so that the auxiliary wheel 4 or 5 contacts the height difference. In this way, when crossing the height difference, the contact position of the auxiliary wheel 4 or 5 will surely fall on the upper surface 303a of the height difference, and compared with the auxiliary wheel 4 or 5 contacting the ground, the descending amount of the fork is reduced.

[0159] In particular, in the first embodiment, an auxiliary wheel 4 is provided in front of the driven wheel 3 (in the insertion direction of the fork 1), and the positional relationship between the auxiliary wheel 4 and the driven wheel 3 changes with the detection result of the drop detection device 17, thereby reducing the resistance when the fork 1 of the pallet truck 100 is inserted into the pallet 300.

[0160] In the second embodiment, an auxiliary wheel 5 is provided behind the driven wheel 3 (in the direction of pulling out the fork 1), and the positional relationship between the auxiliary wheel 5 and the driven wheel 3 changes according to the detection result of the drop detection device 18, thereby reducing the resistance when the fork 1 is pulled out from the pallet 300 by the pallet truck 100.

[0161] In the third embodiment, auxiliary wheels 4 and 5 are respectively provided in front of the driven wheel 3 (in the insertion direction of the fork 1) and in the rear (in the withdrawal direction of the fork 1), and the positional relationship between the auxiliary wheels 4, 5 and the driven wheel 3 changes according to the detection results of the drop detection devices 17, 18, respectively, thereby reducing the resistance when the pallet truck 100 inserts the fork 1 into the pallet 300 and when the fork 1 is withdrawn from the pallet 300.

[0162] The drop height of a 1100×1100 size pallet generally used in Japan is about 15mm, and the height of the insertion hole is about 90mm. In comparison, the height of the fork of the pallet truck 100 is about 50mm to 60mm, and the range of motion in the lifting direction when the fork is inserted is only about 30mm. Therefore, reducing the lifting amount of the fork 1 is an effective method to reduce the resistance when the fork is inserted into the pallet 300 of general specifications and when the fork is withdrawn.

[0163] In the case of the third embodiment, it is necessary to have space for installing auxiliary wheels 4 and 5 on both the front and rear sides of the driven wheel 3. On the other hand, in the case of the first or second embodiment in which the auxiliary wheel 4 or the auxiliary wheel 5 is installed on either the front or rear side of the driven wheel 3, even if there is no space for installing auxiliary wheels on both the front and rear sides of the driven wheel 3, when a pallet 300 with a low height 303 is used, or when the height difference can be crossed by making the auxiliary wheel 4 or the auxiliary wheel 5 contact the ground, the present invention is expected to play a role.

[0164] That is to say, when the lifting amount of the fork 1 when crossing the drop is suppressed to a minimum, auxiliary wheels 4 and 5 are set on the front and rear sides of the driven wheel 3. When there is no space for setting auxiliary wheels on the front and rear sides of the driven wheel 3, auxiliary wheels 4 or auxiliary wheels 5 are set on either side of the front and rear of the driven wheel 3. This can reduce the impedance caused by inserting or withdrawing the fork, and is therefore effective.

[0165] The following describes the dimensions of the driven wheels 3, auxiliary wheels 4 and 5, and fork 1 used for the pallet truck 100. Here, the driven wheels 4 and 5 are of the same diameter and made of the same material.

[0166] · Driven wheel: diameter 80 mm, made of nylon, load-bearing capacity 1000 kg, maximum load-bearing weight 1000 kg

[0167] · Auxiliary wheel: diameter 35 mm, made of nylon, load-bearing capacity 120 kg, the smallest diameter of the bearing wheel that is easy to purchase

[0168] · Tray size: width 1100 mm, depth 1100 mm, height 120 mm

[0169] · Drop height: 15 mm

[0170] · Drop depth: 90 mm (measured value of wooden tray), 150 mm (measured value of plastic tray)

[0171] · Jacking hole height: 90 mm

[0172] · Fork height: 60 mm

[0173] Distance from the upper surface of the fork to the central axis of the auxiliary wheel: 60 mm

[0174] In order to ensure the gap between the driven wheel 3 that can move by the lifting of the fork 1 and the auxiliary wheels 4 and 5 mounted on the fork 1, when inserting a tray with a height of 90 mm into the jacking hole, a gap is generated when the diameter of the auxiliary wheel is small, and it is necessary to set the distance between the central axis (15) of the driven wheel and the central axes (16, 12) of the auxiliary wheels to 90 mm or less (the depth dimension of the tray difference). It is better that the diameter of the auxiliary wheel is smaller.

[0175] Figure 57 Shows the wheel configurations for facilitating the tray drop of a manual pallet truck in the past. Among them, (a) shows the configuration of the prior art example 1 with a driven wheel 3A and an auxiliary wheel 4A located in front of the driven wheel and fixed to the fork, (b) shows the configuration of the prior art example 2 with two driven wheels 3A, 3A connected by a connecting rod, and (c) shows the configuration of the comparative example 1 combined with the prior art examples 1 and 2.

[0176] The present inventor implemented a Figure 57 simulation comparing the three configurations shown and the configuration of the first embodiment described in the embodiments. The results are as Figure 58 shown.

[0177] The simulation was carried out with the following four wheel configurations.

[0178] · Having a driven wheel 3A and an auxiliary wheel 4A located in front of the driven wheel and fixed to the fork ( Figure 57 (a))

[0179] · Having a configuration with two driven wheels 3A, 3A connected by a connecting rod ( Figure 57 (b))

[0180] · Two follower wheels 3A, 3A connected by a connecting rod and an auxiliary wheel 4A fixed to the forklift in front of them ( Figure 57 (c))

[0181] · Wheel configuration of the first embodiment (see Figure 7 ).

[0182] The pallet conditions during simulation are as follows.

[0183] (Condition 1) Weight of the pallet

[0184] · 4.8 kg (measured weight of a wooden pallet with a general A3 size (950 mm × 650 mm) in the printing industry)

[0185] · 10 kg (measured weight of a general 1100 mm × 1100 mm plastic pallet in Japan)

[0186] · 15 kg (measured weight of a general 1100 mm × 1100 mm wooden pallet in Japan)

[0187] · 20 kg, · 30 kg, · 40 kg

[0188] · Static friction coefficient of the pallet 0.22 (measured with a spring scale)

[0189] · Pallet drop height 15 mm

[0190] The conditions of the traveling device (pallet truck 100) during simulation are as follows.

[0191] · Forklift weight: 20 kg

[0192] · Follower wheel diameter: 80 mm

[0193] · Auxiliary wheel diameter: 35 mm

[0194] · Height of the auxiliary wheel from the ground during insertion: 11.5 mm (height relative to the drop is 3.5 mm)

[0195] · Traveling speed during insertion: 0.2 m / s

[0196] Under the above conditions, the simulation results of the fork inserting into the pallet with various wheel configurations show that for an empty pallet without goods loaded on it, compared with the prior art example 1, the wheel configurations of the prior art example 2 and the comparative example 1 can cross the drop with a lighter pallet. However, even with the configurations of the prior art example 2 and the comparative example 1, when the weight of the pallet is below a certain level, the drop cannot be crossed. Therefore, the weight that can cross the drop has little difference from the frictional force acting on the floor where the pallet is placed. The lateral force exerted by the driven wheel on the drop when crossing the drop has a greater impact than the static friction of the pallet. Therefore, it can be listed as one of the main reasons for the movement of the pallet.

[0197] In this regard, even when performing the fork insertion operation on the lightest pallet (4.8 kg), the wheel configuration of the fork of the present invention can cross the drop. It can be speculated that the reason is that in the case of the configuration of the present embodiment, as Figure 12 , Figure 13 shown, when the fork 1 performs the insertion operation, the driven wheel 3 is lifted upward, and only the auxiliary wheel 4 contacts the drop 303. Therefore, the lateral (fork insertion direction) force exerted on the drop 303 is less than the static friction of the pallet 300. It can also be speculated that when the driven wheel 3 is located above the drop 303, as Figure 14 , Figure 15 shown, the driven wheel 3 descends and moves in contact with the upper surface 303a of the drop. Therefore, in order to exert pressure on the drop 300, as a result, the static friction of the pallet 300 is increased.

[0198] The preferred embodiments of the present invention have been described. The present invention is not limited to specific embodiments. As long as there is no special limitation in the above description, within the scope of the gist of the present invention described in the patent application, various deformations and changes can be made. For example, as a rotating body, for shapes such as rollers and rolls that can make point or line contact with the ground, as long as they are rotatably supported, they are not limited to wheels.

[0199] As an example of the traveling device, in the embodiment, the automatically traveling pallet truck 100 is used as an example for description. However, the configuration of the traveling device is not limited to this type. For example, a manual type traveling device that lifts and lowers the fork 1 by operating a currently known operating part, a traveling device that does not perform automatic traveling but lifts and lowers the fork 1 by a drive source, can also adopt the configuration in which the driven wheel 3 of the present invention moves up and down as the fork lifts and lowers, and the configurations of the auxiliary wheels 4 and 5, and the drop detection devices 17 and 18, to obtain the same effects as those described in this specification.

[0200] The effects described in the embodiments of the present invention only list the best effects obtained by the present invention, and the effects of the present invention are not limited by the content described in the embodiments of the present invention.

Claims

1. A traveling device that can move forward and backward relative to the object to be carried, characterized in that, it has, a fork, one end of the fork is supported by the main body, and the other end protrudes from the main body, and the object to be carried is loaded by inserting the other end into the object to be carried; a rotating body, which is installed at the other end of the fork through a connecting mechanism, so that when the fork rises, the rotating body moves downward relative to the fork, and when the fork descends, the rotating body moves upward relative to the fork; an auxiliary rotating body, the auxiliary rotating body is at a front rotating body connection position closer to the front end of the fork than the rotating body in the fork insertion direction or at a rear rotating body connection position closer to the rear end of the fork than the rotating body in the fork extraction direction, and the distance between the central axis of the auxiliary rotating body and the central axis of the rotating body is less than the depth dimension of the drop provided on the object to be carried; a drop detection device for detecting the drop provided on the object to be carried, the drop detection device is configured to, when detecting the drop on the object to be carried, load the object to be carried with the fork in the following manner, that is, detect the distance between the fork and the drop, raise and lower the fork so that the auxiliary rotating body is at a position higher than the upper surface of the drop, insert the fork until the auxiliary rotating body reaches above the drop, lower the fork until the rotating body is at a position higher than the auxiliary rotating body, insert the fork in a state where the auxiliary rotating body contacts the upper surface of the drop until the rotating body reaches above the drop, raise the fork until the rotating body touches the ground, insert the fork in a state where the rotating body contacts the upper surface of the drop until the rotating body descends from the drop.

2. The traveling device according to claim 1, characterized in that, the auxiliary rotating body is installed at the front rotating body connection position, and the drop detection device is installed at the front detection device connection position.

3. The traveling device according to claim 1, characterized in that, the auxiliary rotating body is installed at the rear rotating body connection position, and the drop detection device is installed at the rear detection device connection position.

4. The traveling device according to claim 1, characterized in that, the auxiliary rotating bodies are respectively installed at the front rotating body connection position and the rear rotating body connection position, and the drop detection devices are respectively installed at the front detection device connection position and the rear detection device connection position.

5. The traveling device according to any one of claims 1 to 4, characterized in that, the lifting mechanism is configured to support one end of the fork through the main body, and the fork is further configured to be able to be lifted and lowered by using the lifting mechanism.

6. The traveling device according to claim 5, characterized in that, the drop detection device is arranged at a front detection device connection position closer to the front end of the fork than the auxiliary rotating body in the fork insertion direction, or at a rear detection device connection position closer to the rear end of the fork than the auxiliary rotating body in the fork extraction direction.

7. The traveling device according to any one of claims 1 to 4, characterized in that, the main body is provided with a driving rotating body driven by a driving source, and the driving rotating body is a driven rotating body.

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