Traction trolley

Abstract

To provide a tow cart that can tow plural carts and makes it possible to reduce a turning radius difference between inner wheels.SOLUTION: A tow cart 1 includes a 4WS mechanism 21 including front wheels 31A that are stationary wheels, rear wheels that are stationary wheels, and a link part that rotates one of the front wheels and rear wheels along with the rotation of the other of the front wheels and rear wheels about a gravity direction, a tow part 22 having plural casters 212 that are free wheels, are fixed to the 4WS mechanism, and tows the cart or has a pallet placed on the top, and a coupling part 12 capable of being coupled to a carrier 100. The length of the 4WS mechanism in an advancing direction is shorter than the length of the tow part.SELECTED DRAWING: Figure 1

Description

Technical Field

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[0001] Embodiments of the present invention relate to a towing carriage.

Background Art

[0002] As an instrument for loading and moving goods on a factory production line or the like, carts and pallets are known. Carts and pallets are, for example, connected or placed on a transport vehicle and transported together with the loaded goods. As the transport vehicle, for example, an unmanned transport vehicle such as an AGV (Automatic Guided Vehicle) that is guided by the magnetism emitted by a magnetic tape or magnetic rod laid on the floor surface and travels unmanned, or a manned transport vehicle such as a turret truck or an electric towing vehicle operated by an operator is known. Also known is a towing carriage that can tow a plurality of carts by being towed by an AGV or the like (see, for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

[0007] According to the present invention, it is possible to provide a towing trolley that can tow multiple trolleys and reduce the difference in inner wheel radius. [Brief explanation of the drawing]

[0008] [Figure 1] A perspective view showing the configuration of a towing traction vehicle according to the first embodiment of the present invention. [Figure 2] A perspective view showing the configuration of the traction truck. [Figure 3] This is an exploded perspective view showing a modified example of the 4WS mechanism in the configuration of the same towing traction vehicle. [Figure 4] An exploded perspective view showing the configuration of the traction truck. [Figure 5] An exploded perspective view showing the configuration of the 4WS mechanism and connecting section. [Figure 6] An exploded perspective view showing the link section, caster, and connecting section of the 4WS mechanism. [Figure 7] An explanatory diagram showing an example of evaluation test 1 for the towing traction unit. [Figure 8] This is an explanatory diagram schematically showing the trajectory as a result of evaluation test 1 of the towing traction unit. [Figure 9]Explanatory drawing showing the results of Evaluation Test 1 of the same towing cart. [Figure 10] Explanatory drawing showing the results of Evaluation Test 2 of the same towing cart. [Figure 11] Explanatory drawing showing the results of Evaluation Test 2 of the same towing cart. [Figure 12] Perspective view showing the configuration of the towing cart according to the second embodiment of the present invention. [Figure 13] Perspective view showing the configuration of the same towing cart. [Figure 14] Perspective view showing the configuration of the towing cart according to the third embodiment of the present invention. [Figure 15] Perspective view showing the configuration of the same towing cart. [Figure 16] Exploded perspective view showing the configuration of the same towing cart. [Figure 17] Perspective view showing the configuration of the towing cart according to the fourth embodiment of the present invention. [Figure 18] Perspective view showing the configuration of the same towing cart. [Figure 19] Perspective view showing the configuration of the same towing cart. [Figure 20] Perspective view showing the configuration of the same towing cart.

Mode for Carrying Out the Invention

[0009] (First Embodiment) Hereinafter, the configuration of the towing cart 1 according to the first embodiment of the present invention will be described with reference to FIGS. 1 to 6.

[0010] FIG. 1 is a perspective view showing the configuration of the towing cart 1 according to the first embodiment of the present invention, FIG. 2 is a perspective view showing the configuration of the towing cart 1, and FIG. 3 is a perspective view showing a modified example of the configuration of the towing cart 1 in which the length of the 4WS mechanism unit 21 is changed. FIG. 4 is an exploded perspective view showing the configuration of the towing cart 1, FIG. 5 is an exploded perspective view showing the configuration of the 4WS mechanism unit 21 and the connecting unit 12, and FIG. 6 is an exploded perspective view showing the configuration of the caster 31 and the link unit 32 of the 4WS mechanism unit 21 and the connecting unit 12.

[0011] As shown in Figures 1 and 2, the towing trolley 1 is connected to the transport vehicle 100 by a coupling part 12 and is a transport jig that moves along the floor surface by casters 31 and 51 as the transport vehicle 100 moves. The towing trolley 1 is towed by the transport vehicle 100 while holding multiple trolleys 200 or pallets by a base 11. In this embodiment, the towing trolley 1 is configured to tow multiple trolleys 200.

[0012] First, I will explain the transport vehicle 100 and the trolley 200.

[0013] The transport vehicle 100 is an unmanned transport vehicle such as an AGV (Automatic Guided Vehicle), or a manned transport vehicle such as a turret truck or an electric towing vehicle. In this embodiment, the transport vehicle 100 will be referred to as AGV100 and described below. For example, the AGV100 is guided by magnetic fields emitted from magnetic tapes or magnetic rods laid on the floor along a transport route, and travels unmanned for transporting goods within a factory premises. The AGV100 has a coupling part that is connected to the towing trolley 1.

[0014] As shown in Figure 1, the trolley 200 comprises a loading platform 211 and a plurality of casters 212 attached to the loading platform 211. For example, the trolley 200 is a cage trolley or a flatbed trolley. In this embodiment, an example using a cage trolley will be described. Hereafter, the trolley 200 will be described as a cage trolley 200.

[0015] The cage trolley 200 comprises a loading platform 211, a plurality of casters 212 attached to the loading platform 211, and a railing 213. The loading platform 211 is formed, for example, in the shape of a rectangular flat plate, so that a load can be placed on it.

[0016] Casters 212 are provided, for example, one at each of the four corners of the loading platform 211, so as to be able to support the platform and move along the floor. Casters 212 are, for example, swivel wheels. Fences 213 are provided, for example, along three sides of the loading platform 211 perpendicular to the loading surface to prevent the load from falling off the platform 211. Fences 213 are provided along all four sides of the loading platform 211 and may be configured to be partially openable and closable.

[0017] Next, the towing trolley 1 will be described. As shown in Figures 1 to 6, the towing trolley 1 comprises a base 11 and a connecting part 12. The towing trolley 1 covers the cage trolley 200 with the base 11, and when towed, it tows the cage trolley 200 which is placed inside the base 11.

[0018] As shown in Figures 1 to 4, the base 11 comprises a 4WS mechanism 21 and a traction unit 22.

[0019] As shown in Figures 5 and 6, the 4WS mechanism 21 comprises four first casters 31, a link section 32, a mounting section 33, two (a pair of) rotating discs 34, and a weight 35.

[0020] The first caster 31 is a fixed wheel. The first caster 31 is configured such that a wheel 31c is rotatably attached to a fork 31a provided on the link section 32 by a hinge pin 31b or the like. Of the four first casters 31, two constitute the front wheels 31A, and the remaining two constitute the rear wheels 31B. When the direction along the direction of travel of the towing trolley 1 is defined as the longitudinal direction, the longitudinal distance (axle distance) (or the distance between the pair of rotating discs 34) L1 between the front wheels 31A and the rear wheels 31B is shorter than the longitudinal length L2 of the towing section 22. Preferably, the axle distance L1 between the front wheels 31A and the rear wheels 31B is at least 1 / 4 of the longitudinal length L2 of the towing section 22, and shorter than the longitudinal length L2 of the towing section 22. More preferably, the distance L1 between the front wheels 31A and the rear wheels 31B is at least half the length L2 of the traction unit 22 in the longitudinal direction, and shorter than three-quarters of the length L2 of the traction unit 22 in the longitudinal direction.

[0021] That is, the distance L1 between the front wheels 31A and the rear wheels 31B of the 4WS mechanism unit 21 is such that L1 < L2, preferably L2 / 4 ≤ L1 < L2, and more preferably L2 / 2 ≤ L1 < 3·L2 / 4. Among a plurality of second casters 51 described later in the towing unit 22, when the distance between the front wheels 51A and the rear wheels 51B during traveling is L3, the distance L1 between the front wheels 31A and the rear wheels 31B is such that L1 < L3, preferably L3 / 4 ≤ L1 < L3, and more preferably L3 / 2 ≤ L1 < 3·L3 / 4 may be set. Also, the length L2 and the distance L3 may be the same length. As a specific example, FIG. 2 shows a towing cart 1 in which L1 is set to 1500 mm and L3 is set to 2520 mm. As long as L1 and L2 (or L3) are in the above relationship, the 4WS mechanism unit 21 can be set as appropriate. Also, as another specific example, FIG. 3 illustrates a towing cart 1 in which L1 is set to 1200 mm, which is shorter than the 4WS mechanism unit 21 in FIG. 2.

[0022] The link portion 32 includes a front wheel mounting portion 41, a rear wheel mounting portion 42, a first link member 43, a second link member 44, and a link rotating member 45. The width of the link portion 32 is formed smaller than the mounting width of the caster 212 in the width direction of the cart 200. Also, the width of the link portion 32 is set to a dimension that does not contact the caster 212 even when the caster 212 is eccentric inward.

[0023] Two first casters 31 (front wheels 31A) are provided on the front wheel mounting portion 41. For example, the fork 31a of the front wheel 31A is fixed to the lower surface of the front wheel mounting portion 41. The front wheel mounting portion 41 is fixed to the mounting portion 33 so as to be rotatable around a single axis. The front wheel mounting portion 41 is formed in a plate shape or a frame shape. The front wheel mounting portion 41 is formed to be able to mount two first casters 31 separated by a predetermined distance in the width direction orthogonal to the traveling direction and the gravitational direction of the towing cart 1. Also, the front wheel mounting portion 41 is formed to be able to mount the connecting portion 12. For example, the front wheel mounting portion 41 has a connected portion 41a fixed to the upper surface of the front wheel mounting portion 41 by a fastening member 99 such as a bolt that can rotatably mount the connecting portion 12 around a single axis along the width direction.

[0024] Two first casters 31 (rear wheels 31B) are attached to the rear wheel mounting section 42. For example, the forks 31a of the rear wheels 31B are fixed to the lower surface of the rear wheel mounting section 42. The rear wheel mounting section 42 is fixed to the mounting section 33 so as to be rotatable around a single axis. The rear wheel mounting section 42 is formed in the shape of a plate or a frame. The rear wheel mounting section 42 is formed so as to be able to accommodate two first casters 31 spaced a predetermined distance apart in the width direction perpendicular to the direction of travel and the direction of gravity of the towing trolley 1. For example, the predetermined distance in the width direction of the two first casters 31 attached to the rear wheel mounting section 42 is the same as the predetermined distance in the width direction of the two first casters 31 attached to the front wheel mounting section 41. The rear wheel mounting section 42 is attached to the mounting section 33 so as to be rotatable around a single axis along the direction of gravity.

[0025] The first link member 43 is formed in a plate shape that is long in one direction. One end of the first link member 43 is rotatably attached to the front wheel mounting portion 41 on one end side, for example the right side, in the width direction, via a washer 97 made of POM (polyoxymethylene) or the like, by fastening members 99 such as hinge pins, bolts and nuts. The other end of the first link member 43 is rotatably attached to the link rotation member 45 via a washer 97 made of POM (polyoxymethylene) or the like, by fastening members 99 such as hinge pins, bolts and nuts.

[0026] The second link member 44 is formed in a plate shape that is long in one direction. One end of the second link member 44 is rotatably attached to the rear wheel mounting portion 42 on one end side, for example the right side, in the width direction of the rear wheel mounting portion 42 via a washer 97 made of POM (polyoxymethylene) or the like, and fastening members 99 such as hinge pins, bolts and nuts. The other end of the second link member 44 is spaced apart from the other end of the first link member 43 and is rotatably attached to the link rotation member 45 via a washer 97 made of POM (polyoxymethylene) or the like, and fastening members 99 such as hinge pins, bolts and nuts.

[0027] The link rotating member 45 is fixed to the mounting portion 33 by fastening members 99 such as hinge pins, bolts and nuts, via a washer 97 made of POM (polyoxymethylene) or the like, so that it can rotate around one axis.

[0028] In this type of link section 32, when one of the front wheel mounting section 41 (front wheel 31A) and the rear wheel mounting section 42 (rear wheel 31B) rotates around an axis aligned with the direction of gravity, one of the first link member 43 and the second link member 44 moves, causing the link rotating member 45 to rotate. The rotation of the link rotating member 45 then moves the other of the first link member 43 and the second link member 44, causing the other of the front wheel mounting section 41 (front wheel 31A) and the rear wheel mounting section 42 (rear wheel 31B) to rotate around an axis aligned with the direction of gravity in the opposite direction to the other of the front wheel mounting section 41 (front wheel 31A) and the rear wheel mounting section 42 (rear wheel 31B).

[0029] The mounting portion 33 is formed in the shape of a rectangular frame that is elongated in one direction. The front wheel mounting portion 41 is connected to one end of the mounting portion 33 via a rotating disc 34, and the rear wheel mounting portion 42 is connected to the other end of the mounting portion 33 via a rotating disc 34.

[0030] The mounting portion 33 has a plurality of fixing portions 33a at its tip for fixing the traction portion 22 at multiple locations in the width direction. For example, two fixing portions 33a are provided spaced a predetermined distance apart in the width direction. The fixing portion 33a comprises, for example, two support columns 33b provided in the front-rear direction that protrude from the upper surface of the tip of the mounting portion 33, and a pair of plates 33c provided on each support column 33b, which constitute a seating surface for fastening members 99 such as bolts. A part of the trolley holding portion 52 of the traction portion 22, described later, is placed between the pair of plates 33c, and the pair of plates 33c are fastened with fastening members 99, and the pair of plates 33c are fastened to the support columns 33b with fastening members 99, thereby fixing the traction portion 22 to the mounting portion 33. The fixing portion 33a is fixed, for example, to the base frame 61b and holding frame 61c of the trolley holding portion 52, described later.

[0031] The rotating disc 34 connects the front wheel mounting section 41 and the rear wheel mounting section 42 to the mounting section 33 so that they can rotate around a single axis aligned with the direction of gravity. For example, the rotating disc 34 has a pair of plate-shaped movable bodies 34a that can slide or move relative to each other in the rotational direction around a single axis, with one movable body 34a fixed to the front wheel mounting section 41 and the rear wheel mounting section 42 by fastening members 99 such as screws or bolts, and the other movable body 34a fixed to the mounting section 33 by fastening members 99.

[0032] The weight 35 is provided on the upper part of the mounting portion 33 to apply a predetermined load to the front wheel 31A and the rear wheel 31B. The weight 35 is fixed to the upper surface of the mounting portion 33 by fastening members 99 such as bolts or adhesive. The weight 35 is formed in the shape of a thin plate so that its weight can be adjusted, and the total weight can be adjusted by adjusting the number of plates.

[0033] As shown in Figures 1 to 4, the traction unit 22 includes a plurality of second casters 51 and a trolley holding unit 52.

[0034] The second caster 51 is a free-moving wheel. The second caster 51 is fixed to the trolley support section 52, for example, by fastening members 99 such as bolts. The second caster 51 is provided, for example, in three locations in the front-to-back direction and in pairs in the width direction. In other words, six second casters 51 are provided. The number of second casters 51 is set appropriately depending on the shape of the trolley support section 52, the trolley 200 to be towed, and the load capacity of the trolley 200.

[0035] The second caster 51 includes, for example, a mounting seat 51a fixed to the lower surface of the trolley holding portion 52 by a fastening member 99, a fork 51b rotatably connected to the mounting seat 51a by a rotation axis aligned with the direction of gravity, and a wheel 51c rotatably mounted on the fork 51b via a shaft. The wheel 51c of the second caster 51 has a diameter that allows it to be positioned at a height that allows the trolley holding portion 52 to contact the cage trolley 200. For example, the diameter of the wheel 51c of the second caster 51 is formed to be larger than the diameter of the wheel 31c of the first caster 31. However, as long as the trolley holding portion 52 can contact the cage trolley 200, the wheel 31c of the first caster 31 and the wheel 51c of the second caster 51 may be the same shape (same diameter), and the wheel 31c of the first caster 31 may be larger in diameter than the wheel 51c of the second caster 51.

[0036] Of the six second casters 51, two second casters 51 constitute the front wheels 51A, two second casters 51 constitute the rear wheels 51B, and the remaining two second casters 51 constitute the central wheel 51C, which is positioned between the front wheels 51A and the rear wheels 51B.

[0037] The trolley holding section 52 comprises a frame 61 having an opening 61a that can accommodate multiple cage trolleys 200 inside and is partially open to allow the cage trolleys 200 to move inside, and one or more stoppers 62 that are movably mounted on the frame 61 and open and close the opening 61a, and partition the inside of the frame 61. The opening 61a and the stoppers 62 that open and close the opening 61a constitute a gate for inserting and removing the cage trolleys 200 into and out of the trolley holding section 52.

[0038] The frame 61 is formed in the shape of a rectangular frame that is long in the front-rear direction. The frame 61, for example, constitutes an opening 61a with an opening at its rear end. The opening 61a is formed to have an opening width that allows the cage trolley 200 housed within the frame 61 to move. The width of the frame 61 is formed to be slightly larger than the width of the cage trolley 200 and larger than the width of the 4WS mechanism 21. The frame 61 comprises, for example, a base frame 61b on which the second caster 51 is provided, a holding frame 61c that extends upward and inward from the base frame 61b and constitutes a surface that contacts the cage trolley 200, and a cushioning material 61d provided on the front rear surface of the holding frame 61c. For example, the base frame 61b and the holding frame 61c are provided at the front and left and right, respectively, and are formed in a U-shape that extends in the width direction at the front in the direction of travel and extends in the direction of travel to both sides in the width direction.

[0039] The cushioning material 61d absorbs the impact of the cage trolley 200 upon contact. One or more cushioning materials 61d are provided on the surface of the retaining frame 61c, which is positioned at the front and faces the cage trolley 200. The cushioning material 61d is formed from an elastically deformable member, such as a rubber member, a foamed resin material, or a hollow member.

[0040] The stopper 62 is formed to restrict the movement of the cage trolley 200, which is positioned within the frame 61. The stopper 62 is also formed to switch between a state in which the cage trolley 200 is movable within the frame 61 and a state in which its movement is restricted. For example, the stopper 62 rotates between two positions: a lateral position perpendicular to both the longitudinal direction and the direction of gravity of the frame 61, and an upright position aligned with the direction of gravity. In the lateral position, the stopper 62 restricts the movement of the cage trolley 200, and in the upright position, it allows the movement of the cage trolley 200.

[0041] For example, the number of stoppers 62 provided is equal to the number of cage trolleys 200 housed within the frame 61. Alternatively, only one stopper 62 may be provided to open and close the opening 61a. In this embodiment, the stoppers 62 are provided at two locations: the rear end and an intermediate position of the traction section 22. As shown in Figure 4, the stopper 62 comprises a base 62a, a stopper body 62b rotatably mounted on the base 62a within a predetermined angular range, a cushioning material 62c, and a contact member 62d. In a lateral position, the upper surface of the stopper 62 is flush with the upper surface of the frame 61, or lower than the upper surface of the frame 61.

[0042] The base portion 62a is provided on one of the left or right sides of the frame 61. The base portion 62a is formed in a rectangular cylindrical shape. The base portion 62a has elongated holes 62e extending in the direction of gravity on both sides in the front-rear direction. In addition, in the width direction (left-right direction), the outer side of the base portion 62a has a wall portion up to the uppermost end of the base portion 62a, while the inner side is lower than the uppermost end of the base portion 62a.

[0043] The stopper body 62b is formed in the shape of a rectangular rod. The stopper body 62b has an external shape that allows it to be inserted into the base 62a. The stopper body 62b has an elongated hole 62f extending in the direction of gravity and bending outward in an upright position at its lower end, on both sides in the front-rear direction on one end. The stopper body 62b is connected to the base 62a so as to be rotatable and movable by fastening members 99 such as truss screws and nuts that are inserted through the elongated hole 62f and the base 62a.

[0044] The cushioning material 62c absorbs the impact of the cage trolley 200 upon contact. One or more cushioning materials 62c are provided on the surface of the stopper body 62b facing the cage trolley 200. The cushioning material 62c is formed from an elastically deformable member, such as a rubber member, a foamed resin material, or a hollow member.

[0045] The contact member 62d is provided on the end face of one end facing the frame 61 of the stopper body 62b. By contacting the frame 61, the contact member 62d defines the position of the stopper body 62b. For example, the contact member 62d is a contact rubber formed of an elastic body such as a rubber material.

[0046] Also, the 4WS mechanism unit 21 and the traction unit 22 are set in the following relationship. The width orthogonal to the traveling direction of the 4WS mechanism unit 21 is smaller than the width orthogonal to the traveling direction of the traction unit 22. That is, the width between the first casters 31 arranged in the width direction of the 4WS mechanism unit 21 and the width of the link portion 32 are set to be smaller than the width between the second casters 51 arranged in the width direction and the width of the carriage pressing portion 52.

[0047] The base 11 and the cage carriage 200 configured as described above are set in the following relationship. As shown in FIG. 4, when the height from the ground contact surface of the first caster 31 of the 4WS mechanism unit 21 to the upper surface of the attachment portion 33 is H1, the height from the ground contact surface of the second caster 51 of the traction unit 22 to the upper part (holding frame 61c) of the frame 61 is H2, the height from the ground contact surface of the caster 212 of the cage carriage 200 to the lower surface of the loading platform 211 is H3, and the height from the ground contact surface of the caster 212 of the cage carriage 200 to the upper surface of the loading platform 211 is H4, the relationship of H1 < H3 < H4 ≦ H2 is set. Also, when the height from the ground contact surface of the second caster 51 to the stopper 62 in the horizontal posture is H5, the relationship of H4 ≦ H2 ≦ H :5 is set. That is, the towing carriage 1 is formed so as to be able to contact the fence 213 of the cage carriage 200 as an example, but it may be configured to be able to contact the loading surface (loading platform 211).

[0048] Therefore, when the towing trolley 1 and the cage trolley 200 are set up in this relationship, the cage trolley 200 will come into contact with the towing section 22 in the direction of travel and in the width direction when the towing trolley 1 is towed by an AGV 100 or the like. Specifically, in the direction of travel, the front side of the railing 213 of the foremost cage trolley 200 can come into contact with the back of the front holding frame 61c, and the rear side of the railing 213 of each cage trolley 200 can come into contact with the front of the stopper 62. In the width direction, the side of the railing 213 of each cage trolley 200 can come into contact with the outer surface of the holding frame 61c in the width direction. When the stopper 62 in the center of the frame 61 is in an upright position, the front-to-rear sides of adjacent cage trolleys 200 arranged in the direction of travel can come into contact with each other. Therefore, when the towing trolley 1 is moving, the cage trolley 200 comes into contact with the towing section 22, so the towing trolley 1 can tow the cage trolley 200.

[0049] The connecting portion 12 is provided on the base 11 and is configured to be connectable to the AGV 100. As a specific example, as shown in Figures 1 to 6, the connecting portion 12 is connected, for example, to the 4WS mechanism 21 of the base 11. As shown in Figure 3, the connecting portion 12 includes, for example, a mounting portion 12a that is connected to the front wheel mounting portion 41 of the link portion 32 of the 4WS mechanism 21, and a fixing portion 12b that is fixed to the connected portion of the AGV 100. The mounting portion 12a is connected to the connected portion 41a provided on the front wheel mounting portion 41 of the link portion 32 of the 4WS mechanism 21 so as to be rotatable around an axis in the direction of gravity.

[0050] The fixing portion 12b is formed in the shape of a rod extending from the mounting portion 12a and is configured to be fixable to the connected portion of the AGV 100. For example, if the connected portion of the AGV 100 has a cylindrical pin, the fixing portion 12b has a hole at its tip into which the pin is inserted, and the fixing portion 12b is fixed to the connected portion by the engagement of the pin and the hole. In addition, to allow the towing trolley 1 to easily travel along curved routes in its route, the fixing portion 12b is connected to at least one of the mounting portion 12a and the connected portion so as to be rotatable around an axis in a direction perpendicular to both the direction of travel and the width direction (direction of gravity).

[0051] The towing cart 1 configured as described above uses the 4WS mechanism unit 21 and makes the length of the 4WS mechanism unit 21 in the front-rear direction be not less than half of the length of the towing part 22 in the front-rear direction and shorter than the length of the towing part 22 in the front-rear direction. That is, the distance (axial distance) L1 between the front wheels 31A and the rear wheels 31B of the 4WS mechanism unit 21 is not less than half of the length L2 of the towing part 22 in the front-rear direction (the axial distance when the front wheels 51A and the rear wheels 51B of the towing part 22 are running is L3) and shorter than the length L2 of the towing part 22 in the front-rear direction. That is, the axial distance L1 between the front wheels 31A and the rear wheels 31B is set to L2 / 2≦L1<L2 and / or L3 / 2≦L1<L3. Thereby, the towing cart 1 can reduce the inner wheel difference.

[0052] Next, an example of the evaluation test of the towing cart 1 according to the present embodiment will be described with reference to FIGS. 7 to 11. As the evaluation tests, evaluation test 1 and evaluation test 2 were conducted. First, evaluation test 1 will be described.

[0053] As evaluation test 1, as shown in FIG. 7, a running route T having 90° curves with R = 1 m and R = 1.5 m was run using two types of towing carts 1 with the distance L1 between the pair of turntables 34 of the 4WS mechanism unit 21 being 1200 mm (small) and 1500 mm (large). In FIG. 7, C indicates the rotation center (curvature center) of the curve.

[0054] Also, as shown in FIG. 7, when the towing cart 1 is running, when the tip of the frame 61 of the towing part 22 on the rotation center C side from the rotation center C is position A and the rear end of the frame 61 of the towing part 22 on the rotation center C side from the rotation center C is position B, the distances r from the rotation center C to position A and position B, and the distance y from the rotation center C to the direction parallel to the traveling direction up to the direction orthogonal to the traveling direction at position A and position B were measured.

[0055] At this time, the weight 35 was not provided, and the towing cart 1 was towed in a state where the cage cart 200 was not accommodated. Also, as shown in FIG. 7, the trajectories of the towing part 22 at positions (1) to (6) of the running route T are shown.

[0056] Here, position (1) is the position where the tip of the connecting section 12 is in the middle of the curve and forms a 45° angle, and position (2) is the position where the tip of the connecting section 12 is at the end of the curve and forms a 90° angle. Position (3) is 500 mm further from position (2), position (4) is 1000 mm further from position (2), position (5) is 1500 mm further from position (2), and position (6) is 2000 mm further from position (2).

[0057] As a result of Evaluation Test 1, Figure 8 shows the trajectory of the towing traction vehicle 1 in Evaluation Test 1, and Figure 9 shows the measured values ​​in Evaluation Test 1. As is clear from Figures 8 and 9, it was confirmed that the towing traction vehicle 1 equipped with the 4WS mechanism 21 can suppress the inner wheel difference and turn around a curve with R=1m.

[0058] Furthermore, when a comparative example of a towing traction vehicle, which lacked the 4WS mechanism 21 and only had a towing section 22, with the central caster 51 of the towing section 22 being a fixed wheel, and the length L3 of the towing section 22 being 2520 mm, was driven along the same curved route T, the difference in inner wheel radius was large on curves with R=1m, making turning difficult, while turning was possible on curves with R=1.3m or greater. In other words, the minimum turning radius for a towing traction vehicle without the 4WS mechanism 21 is 1.3m, and it became clear that the towing traction vehicle 1 with the 4WS mechanism 21 of this embodiment can suppress the difference in inner wheel radius more effectively than conventional towing traction vehicles.

[0059] Furthermore, as shown in the trajectory diagram in Figure 8 and the measured values ​​in Figure 9, the towing traction truck 1 with a small L1 in the 4WS mechanism 21 had a larger maximum width from the center of rotation C during travel to the end of the towing section 22 opposite the center of rotation C, at both 1m and 1.5m turning radii R of the travel route. These results clearly show that by increasing the size of the 4WS mechanism 21, the inner wheel difference can be further reduced, and the required passage width can be reduced.

[0060] Next, we will explain evaluation test 2. In evaluation test 2, two cage trolleys 200 were placed on the towing trolley 1, and the behavior of the towing trolley 1 when it was driven along the curve of the travel route T was checked to see if sideslip occurred. In addition, as in evaluation test 1, two types of L1, small and large, were used for the 4WS mechanism 21. Weights of 80 kg and 100 kg were loaded onto the rear cage trolley 200, and the weights 35 of the 4WS mechanism 21 were tested in the following cases: 0 kg at the front and rear (no weight 35), 5 kg at the front and rear, and 5 kg at the front and 10 kg at the rear. The trolley was driven along the curve of the travel route T at speeds of approximately 1.5 km / h (slow) and approximately 2.5 km / h (fast), and the driving condition and behavior were judged visually.

[0061] Furthermore, as part of the evaluation, if skidding occurred while driving around a curve, it was rated as "×", and if stable driving was achieved, it was rated as "○". The evaluation results for Evaluation Test 2 are shown in Figures 10 and 11.

[0062] As a result of evaluation test 2, as shown in Figure 10, when the 4WS mechanism 21 was small, sideways slipping or swaying occurred depending on the weight of the cage trolley 200, the weight 35 of the mounting part 33, and the running speed. However, it was found that by adjusting the weight of the weight 35 of the mounting part 33 and the running speed, sideways slipping and swaying could be suppressed, and stable running was possible.

[0063] In contrast, as shown in Figure 11, when the 4WS mechanism 21 was made larger, and the weights 35 of the towing traction truck 1 were set to 5 kg at the front and 10 kg at the rear, stable travel was possible at both R=1m and 1.5m, regardless of the speed of travel.

[0064] This also shows that even if the turning radius is large, the weight of the cage trolley 200 is large, and the centrifugal force due to the weight of the cage trolley 200 is large, increasing the L1 of the 4WS mechanism 21 can suppress lateral slippage and allow for stable travel. Therefore, it has become clear that by appropriately setting the dimensions of the 4WS mechanism 21 and the weight 35 of the mounting part 33 based on the expected load capacity of the cage trolley 200, it is possible to travel along the travel route stably. In each evaluation test, lateral slippage occurred, but since the cage trolley 200 can be towed without lateral slippage by setting the weight, travel speed, and the weight of the cage trolley 200 being transported, this does not mean that the configurations in which lateral slippage occurred in the evaluation test should be excluded from the embodiments.

[0065] In other words, the towing traction truck 1 can reduce the inner wheel difference compared to conventional towing traction trucks by making L1 shorter than L2 (L3), preferably L1 being at least 1 / 4 the length of L2 (L3) and shorter than the longitudinal length L2 of the towing section 22, and more preferably L1 being at least 1 / 2 the length of L2 (L3) and shorter than 3 / 4 the length of L2 (L3).

[0066] As described above, according to the towing trolley 1 of this embodiment, by providing a 4WS mechanism 21 on the towing section 22 and making the length of the 4WS mechanism 21 shorter than the length of the towing section 22, it is possible to tow multiple cage trolleys 200 and reduce the inner wheel difference during travel.

[0067] It should be noted that the present invention is not limited to the embodiments described above. For example, in the example described above, the frame 61 was configured to have a base frame 61b and a retaining frame 61c, but it is not limited to this. Next, a towing trolley 1 according to a second embodiment will be described.

[0068] (Second embodiment) The towing traction vehicle 1 according to the second embodiment will be described using Figures 12 and 13. Note that components of the towing traction vehicle 1 according to the second embodiment that are the same as those of the towing traction vehicle 1 according to the first embodiment are denoted by the same reference numerals, and detailed explanations are omitted.

[0069] For example, as in the second embodiment shown in Figures 12 and 13, the towing section 22 of the towing trolley 1 is configured such that the holding frame 61c is not provided on both sides in the width direction, but only on the front. For example, in the towing trolley 1 shown in Figures 12 and 13, the base frame 61b is set to a height that contacts the loading platform 211 or fence 213 of the cage trolley 200. Even with a towing trolley 1 configured in this way, the inner wheel difference can be reduced by making the 4WS mechanism 21 and the towing section 22 have the above-mentioned relationship of distances L1, L2 (and / or L3).

[0070] Furthermore, the towing trolley 1 may be configured to tow a flatbed trolley instead of a cage trolley 200. For example, when towing a flatbed trolley, the holding frame 61c of the frame 61 may be set to the same height as the flatbed trolley's loading platform, so that the holding frame 61c comes into contact with the flatbed trolley. Alternatively, the height of the holding frame 61c may be made variable to two heights: a first height that contacts the flatbed trolley and a second height that contacts the cage trolley 200. The height of the holding frame 61c may be switched according to the height of the trolley being transported, allowing the trolley to be selected. Also, if trolleys of different heights are used, the trolleys are not limited to flatbed trolleys and cage trolleys, but can be set as appropriate. Furthermore, if the widths of the trolleys are different, the holding frame 61c may be configured to have different widths in addition to heights depending on the orientation.

[0071] Furthermore, although the above example described an example in which the towing trolley 1 tows a cage trolley 200, it is not limited to this. The towing trolley 1 may also be configured to tow a pallet 300. Next, the towing trolley 1 according to the third embodiment will be described.

[0072] (Third embodiment) The towing traction vehicle 1 according to the third embodiment will be described with reference to Figures 14 to 16. Note that components of the towing traction vehicle 1 according to the third embodiment that are the same as those of the towing traction vehicle 1 according to the first embodiment are denoted by the same reference numerals, and detailed explanations are omitted.

[0073] As a third embodiment, the towing trolley 1 for towing the pallet 300 has a base 11 and a connecting part 12, as shown in Figures 14 to 16, and the base 11 comprises a 4WS mechanism part 21 and a towing part 22A.

[0074] The traction unit 22A, which is fixed to the 4WS mechanism unit 21, comprises a second caster 51, a trolley restraining unit 52A which is a grid-like frame on which a pallet 300 can be placed, and a plurality of restricting units 71 provided at the corners and edges of the trolley restraining unit 52A to restrict the movement of the pallet 300.

[0075] The restricting portion 71 is, for example, plate-shaped and contacts a part of the outer surface of the pallet 300 to prevent the pallet from falling off the upper surface of the towing portion 22A. In addition, to provide a function similar to that of the restricting portion 71, the trolley holding portion 52A is equipped with a retaining frame 61c at the front.

[0076] With this configuration, the towing trolley 1 can carry and tow multiple pallets 300.

[0077] Furthermore, as another example of a towing trolley 1 capable of transporting pallet 300, a towing trolley 1 according to a fourth embodiment will be described.

[0078] (Fourth embodiment) The towing traction vehicle 1 according to the fourth embodiment will be described with reference to Figures 17 to 20. Note that components of the towing traction vehicle 1 according to the fourth embodiment that are the same as those of the towing traction vehicle 1 according to the first embodiment are denoted by the same reference numerals, and detailed explanations are omitted.

[0079] The towing trolley 1 is not configured to hold the pallet 300 on the towing section 22A, but rather to transport the pallet trolley 400 that transports the pallet 300.

[0080] Here, as shown in Figures 17 to 19, the pallet trolley 400 includes a plurality of casters 410, for example four swivel wheels, a grid-like or plate-like loading platform 420, and a handle bar 430 for human operation. The loading platform 420 also includes restricting parts 421 provided at the corners to restrict the movement of the pallet 300, and a plurality of pairs of projections 422 extending downward toward the center.

[0081] The restricting portion 421 is, for example, plate-shaped and contacts a part of the outer surface of the pallet 300 to prevent the pallet 300 from falling off the top surface of the loading platform 420.

[0082] The projections 422 are provided in pairs from the underside of the cargo bed 420, spaced apart in the width direction of the cargo bed 420, and multiple pairs of these projections 422 are provided at predetermined intervals in the direction of travel of the towing trolley 1. For example, the spacing between the pairs of projections 422 allows for the placement of the mounting portion 33B of the towing trolley 1, which will be described later. For example, the pairs of projections 422 only need to be spaced apart in the width direction. For example, there are four pairs of projections 422 arranged in the direction of travel, so-called four pairs of projections 422. The number of pairs of projections 422 can be set as appropriate.

[0083] As shown in Figures 17 to 20, the towing trolley 1 according to the fourth embodiment is configured such that, for example, the mounting portion 33B, which is an extension of the mounting portion 33 of the 4WS mechanism 21, functions as the towing portion 22B. Specifically, the mounting portion 33B is part of the 4WS mechanism 21 and has a shape that is longer than L1, and is equipped with a second caster 55, which is a swivel wheel, on the lower surface of its rear end.

[0084] Furthermore, the mounting section 33B includes a retaining frame 61c provided on the upper surface of the front end where the front wheel 31A is located, and a stopper 81 provided at the rear end where the second caster 55 is located. The mounting section 33B is set to a length that allows multiple pallet trolleys 400, for example, two pallet trolleys 400 in this embodiment, to be positioned between the retaining frame 61c and the stopper 81. The shape and dimensions of the first caster 31 and second caster 51 of the towing trolley 1, and the caster 410 of the pallet trolley 400, are set so that the upper surface of the mounting section 33B is lower than the lower surface of the loading platform 420 of the pallet trolley 400.

[0085] The stopper 81 is rotatably fixed to the rear end of the mounting portion 33B. One end of the stopper 81 is, for example, rotatably fixed to the rear end of the mounting portion 33B. The stopper 81 rotates between two positions: a lateral position along the longitudinal direction of the mounting portion 33B as shown in Figures 18 and 19, and an upright position along a direction perpendicular to the longitudinal direction of the mounting portion 33B as shown in Figures 17 and 20. The stopper 81 can also be fixed in both the lateral and upright positions and maintain those positions. The method of fixing the stopper 81 in each position can be set as appropriate; for example, it may be fixed by a fixing pin, or a locking mechanism may be provided. As shown in Figures 18 and 19, the upper surface of the stopper 81 in the lateral position is flush with the upper surface of the mounting portion 33B, or lower than the upper surface of the mounting portion 33B.

[0086] Furthermore, as shown in Figures 17 and 20, the upper surface (tip) of the stopper 81 in the upright position is higher than the upper surface of the mounting portion 33B and higher than the lower surface of the loading platform 420 of the pallet trolley 400. That is, as shown in Figures 17 and 20, the stopper 81 in the upright position is formed to be able to contact the side surface of the pallet trolley 400. This allows the stopper 81 to position the pallet trolley 400 on the mounting portion 33B in the lateral position, and restricts the movement of the pallet trolley 400 positioned on the base 11 in the opposite direction to the direction of travel in the upright position. Note that the towing trolley 1 having such a mounting portion 33B may also be configured to accommodate a flatbed trolley having multiple pairs of protrusions 422 on its underside, rather than a pallet trolley 400.

[0087] Furthermore, the width of the 4WS mechanism 21 perpendicular to the direction of travel is smaller than the width between the casters (casters 410) in a direction perpendicular to the direction of travel of the trolley (pallet trolley 400 in this embodiment) transported by the towing unit 22B.

[0088] Such a towing trolley 1 can tow multiple pallet trolleys 400 by restricting the movement of the pallet trolley 400 in the width direction by inserting a pair of projections 422 into the mounting portion 33B. Furthermore, the distance L1 between the axles of the front wheel 31A and rear wheel 31B of the 4WS mechanism 21 is shorter than the distance L4 from the front wheel 31A of the 4WS mechanism 21 to the second caster 55 of the automatic wheel which is the rear wheel of the mounting portion 33, and is at least half the length of the distance L4. Note that the distance L4 from the front wheel 31A of the 4WS mechanism 21 to the second caster 55 of the automatic wheel which is the rear wheel of the mounting portion 33 is the same distance as L2 and L3 described above. That is, if the towing portion 22B does not have a front wheel, the front wheel 31A of the 4WS mechanism 21 also serves as the front wheel of the towing portion 22B. And a towing trolley 1 with such a configuration can obtain the same effects as the other embodiments described above.

[0089] According to the towing trolley 1 of some embodiments described above, it is equipped with a 4WS mechanism 21 and towing sections 22, 22A, and 22B, and the longitudinal distances L1 and L2 between the 4WS mechanism 21 and the towing sections 22, 22A, and 22B are set to the relationship described above. As a result, the towing trolley 1 can reduce the inner wheel difference regardless of whether the object being towed is a trolley or a pallet. Furthermore, the object being towed and the 4WS mechanism 21 and towing sections 22, 22A, and 22B of the towing trolley 1 are not limited to the examples described above and can be set as appropriate.

[0090] It should be noted that the present invention is not limited to the embodiments described above, and can be modified in various ways during implementation without departing from its essence. Furthermore, each embodiment may be combined as appropriate, and in that case, the combined effects can be obtained. Moreover, the above embodiments include various inventions, and various inventions can be extracted by selecting combinations from the multiple constituent elements disclosed. For example, if the problem can be solved and effects obtained even if some constituent elements are deleted from all the constituent elements shown in the embodiment, then the configuration with these deleted constituent elements can be extracted as an invention. The following is a description equivalent to the invention described in the original claims of this application. [1] A 4WS mechanism having a fixed front wheel, a fixed rear wheel, and a link section that rotates the other of the front wheel and the rear wheel in conjunction with the rotation of one of the front wheel and the rear wheel in the direction of gravity, It has multiple casters that are swivel wheels, fixed to the 4WS mechanism, and a towing unit that either pulls the trolley or places a pallet on its upper surface, A connecting part that can be attached to a transport vehicle, Equipped with, A towing traction vehicle in which the length of the 4WS mechanism in the direction of travel is shorter than the length of the traction section in the direction of travel. [2] The towing traction [3] The length of the 4WS mechanism in the direction of travel is the distance between the axles of the front wheel and the rear wheel, The towing trolley according to [1], wherein the length of the towing section in the direction of travel is the distance between the axles of the front and rear wheels of the caster. [4] The towing trolley according to [1], wherein the towing section has a stopper that restricts the movement of the trolley. [5] The traction unit has a plurality of trolleys arranged inside and a gate through which the trolleys can pass, The stopper is a towing trolley as described in [4] that opens and closes the gate. [6] The 4WS mechanism is connected to the towing trolley described in [1]. [Explanation of symbols]

[0091] 1...Towing trolley, 11...Base, 12...Connecting part, 12a...Mounting part, 12b...Fixing part, 21...WS mechanism part, 22...Towing part, 22A...Towing part, 22B...Towing part, 31...First caster, 31a...Fork, 31A...Front wheel, 31b...Hinge pin, 31B...Rear wheel, 31c...Wheel, 32...Link part, 33...Mounting part, 33a...Fixing part, 33b...Support column, 33B...Mounting part, 33c...Plate, 34...Rotating disc, 34a...Moving body, 35...Weight, 41...Front wheel mounting part, 41a...Connected part, 42...Rear wheel mounting part, 43...First link member, 44...Second link member, 45...Link rotating member, 51...Second caster, 51a...Mounting seat, 51A...Front wheel, 51b...Fork, 51B...Rear Wheel, 51c...wheel, 51C...center wheel, 52...cart restraint, 52A...cart restraint, 55...second caster, 61...frame, 61a...opening, 61b...base frame, 61c...holding frame, 61d...cushioning material, 62...stopper, 62a...base, 62b...stopper body, 62c...cushioning material, 62d...contact member, 62e...elongated hole, 62f...elongated hole, 71...regulating part, 81...stopper, 97...washer, 99...fastening member, 100...transport vehicle, 200...cage cart (cart), 211...loading platform, 212...caster, 213...fence, 300...pallet, 400...pallet cart, 410...caster, 420...loading platform, 421...regulating part, 422...projection, 430...handlebar.

Claims

1. A 4WS mechanism having a mounting portion formed in the shape of a rectangular frame that is long in one direction, two front wheels which are fixed wheels, a front wheel mounting portion to which the two front wheels are fixed, two rear wheels which are fixed wheels, a rear wheel mounting portion to which the two rear wheels are fixed, a rotating disc that connects the front wheel mounting portion and the rear wheel mounting portion to the mounting portion so that the front wheel mounting portion and the rear wheel mounting portion can rotate around a single axis along the direction of gravity, and a link portion that rotates the other of the front wheel mounting portion and the rear wheel mounting portion as one of the front wheel mounting portion and the rear wheel mounting portion rotates around the direction of gravity, A towing unit having multiple casters that are swivel wheels, fixed to the 4WS mechanism, to tow multiple trolleys or to place multiple pallets on its upper surface, A connecting part that can be attached to a transport vehicle, Equipped with, The mounting portion has a fixing portion at its tip for fixing the traction portion, The distance between the axles of the front and rear wheels of the 4WS mechanism in the direction of travel is at least 1 / 4 the length of the traction unit in the direction of travel, and shorter than the length of the traction unit in the direction of travel. A towing trolley in which the width of the 4WS mechanism in the direction of travel is smaller than the width of the towing section in the direction of travel and the width between the casters of the trolley in the direction of travel.

2. The towing trolley according to claim 1, wherein the length of the towing section in the direction of travel is the distance between the axles of the front and rear wheels of the caster.

3. The towing trolley according to claim 1, wherein the towing section has a stopper that restricts the movement of the trolley.

4. The traction unit has multiple trolleys arranged inside and a gate through which the trolleys can pass. The towing trolley according to claim 3, wherein the stopper opens and closes the gate.

5. The towing trolley according to claim 1, wherein the 4WS mechanism is connected to the connecting portion.

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