Traction device

Abstract

To provide a traction device which can more stably tow a carriage with casters.SOLUTION: A traction device 10 is attached to a movable body 11, tows a carriage 13 with casters 14 behind the movable body 11, and comprises: a connection unit 22 which can connect and release the carriage 13; and a fixed wheel unit 23 which is provided connected to the connection unit 22, and has fixed wheels 53a capable of rolling back and forth. The connection unit 22 has a carriage lock part 43, and a lifting drive part 44 for lifting the carriage lock part 43. The connection unit 22 can be connected to the carriages 13 when pushed upward against the same. The fixed wheel unit 23 has a base part 52 to which a downward load is transmitted from the connection unit 22, and a fixed wheel pair 53 which is supported by the base part 52 laterally swingably and in which a plurality of fixed wheels 53a are coaxially located on right and left sides of a swing axis L2 extending back and forth. The plurality of fixed wheels 53a are brought into pressure-contact with a road surface by a downward load from the connection unit 22.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to a towing device that is attached to a moving body and is used to tow a dolly with casters. [Background technology]

[0002] Conventionally, as a towing device that is attached to a moving body and tows a dolly with casters, for example, the following Patent Document 1 is known. Patent Document 1 proposes a connection structure for a basket dolly in a transport vehicle, in which a swingable abutment lever and a stopper member are provided in front and behind a frame that fits under the underside of the cage of the basket dolly, and the basket dolly is sandwiched between the abutment lever and the stopper portion and towed by the transport vehicle. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Utility model registration No. 3228245 Summary of the Invention [Problem to be solved by the invention]

[0004] However, in the towing device of Patent Document 1, unless the rear wheels are fixed, when centrifugal force is generated in the cart during turning, the cart will deviate significantly outward from the travel path of the transport vehicle, making it impossible to tow the cart stably, which is an issue.

[0005] SUMMARY OF THE PRESENT EMBODIMENT An object of the present invention is to provide a towing device capable of towing a caster-equipped cart more stably. [Means for solving the problem]

[0006] In order to achieve the above-mentioned object, the present invention provides a towing device that is attached to a movable body and tows a caster-equipped trolley behind the movable body, comprising a connecting unit capable of connecting and releasing the trolley, and a fixed wheel unit that is connected to the connecting unit and has fixed wheels that can roll back and forth, the connecting unit has a trolley engagement portion and a lifting drive portion that raises and lowers the trolley engagement portion, the trolley engagement portion can be pressed upward to engage the trolley, the fixed wheel unit has a base portion to which downward loads from the connecting unit are transmitted, and a fixed wheel pair that is supported on the base portion so as to be able to swing freely back and forth, and has multiple fixed wheels arranged coaxially on the left and right of the swing axis extending back and forth, and the multiple fixed wheels are pressed against the road surface by the downward load from the connecting unit.

[0007] The fixed wheel unit is connected to the coupling unit by a support arm extending forward and backward, and can be positioned between the bogie connected to the coupling unit and the road surface.

[0008] The base portion may have a fixed base fixed to the support arm, a swinging base supported by the fixed base so as to be swingable left and right about a swing axis and supporting a pair of fixed wheels below the swing axis, and a swing biasing means for keeping the swinging base in a neutral position. It is preferable that all wheels of the caster-equipped dolly are casters. Effect of the Invention

[0009] In the towing device of the present invention, a connecting unit that connects to a trolley can press the trolley upward to engage with the trolley, and a fixed wheel that can roll back and forth is supported on the base to which the downward load from the connecting unit is transmitted, and is pressed against the road surface by the downward load from the connecting unit.Therefore, even if centrifugal force acts on a trolley with casters towed by a moving body, the fixed wheel that is pressed against the road surface can provide friction against the centrifugal force.

[0010] In the fixed wheel unit, multiple fixed wheels that can roll back and forth are arranged coaxially on the left and right of the swing axis that extends back and forth and are supported integrally as a fixed wheel pair and swing back and forth, so when the centrifugal force generated in the bogie from the connecting unit is transmitted to the fixed wheel unit, an outward force acts on the base part and is loaded as an outward force on the fulcrum that supports the fixed wheel pair so that it can swing freely. As a result, the contact pressure of the fixed wheels that are arranged outside the swing axis among the multiple fixed wheels against the road surface increases, and the friction force against the centrifugal force increases.

[0011] Therefore, when a cart with casters is towed by a moving body, even if centrifugal force is generated in the cart, the cart can be prevented from deviating significantly outward from the traveling trajectory of the moving body, and the cart with casters can be towed stably.

[0012] If the fixed wheel unit is connected to the connecting unit by a support arm extending forward and backward and can be positioned between the trolley and the floor surface, multiple fixed wheels can be grounded on the road surface under the trolley connected to the connecting unit, allowing the caster-equipped trolley to be towed stably.

[0013] If the base portion has a fixed base fixed to the support arm, a swinging base supported by the fixed base so as to be freely swingable left and right about the swing axis and supporting a pair of fixed wheels below the swing axis, and a swing biasing means for keeping the swinging base in a neutral position, when centrifugal force is acting on the trolley, the contact pressure of the fixed wheels positioned outside the swing axis against the road surface can be increased, and when centrifugal force is not acting on the trolley, the contact pressure of the multiple fixed wheels against the road surface can be restored to approximately equal levels, making it easier to tow more stably. [Brief description of the drawings]

[0014] [Figure 1] 1 is a side view of a state in which a towing device according to an embodiment of the present invention is attached to a moving body. [Diagram 2] 2A and 2B are perspective views of the towing device of FIG. 1 mounted on a moving body, in which (a) shows a state in which a coupling unit is protruded, and (b) shows a state in which the coupling unit is stored. [Diagram 3]FIG. 2(a) is a perspective view of the traction device, and FIG. 2(b) is a side view. [Figure 4] FIG. 2 is a plan view showing a state in which a bogie is towed by the towing device, in which (a) shows a state in which the coupling unit is not swinging, and (b) shows a state in which the coupling unit is swinging. [Diagram 5] 4A and 4B are perspective views showing an upper part of a swinging coupling part in the traction device, in which (a) shows a state in which the coupling unit is not swinging, and (b) shows a state in which the coupling unit is swinging. [Figure 6] FIG. 4 is an exploded perspective view of a cam mechanism provided in a swing coupling portion of the traction device. [Figure 7] 7A to 7C are diagrams illustrating the operation of the cam mechanism in FIG. 6. [Figure 8] FIG. 4 is a side view illustrating an inter-diagonal biasing means of the traction device. [Figure 9] 13 is a perspective view showing a locking portion of a link mechanism portion provided in a connecting unit of the towing device and a locking portion of a support arm of a fixed wheel unit. FIG. [Figure 10] 10A and 10B are explanatory diagrams of the operation of the locking part of the link mechanism part shown in FIG. 9, in which (a) shows the locked state in which the connecting unit is fully extended, (b) shows the unlocked state, and (c) shows the contracted state of the connecting unit. [Figure 11] FIG. 2A is a perspective view of the coupling unit and fixed wheel unit of the towing device, and FIG. 2B is a perspective view of the inside of the fixed wheel unit through the fixed base. [Figure 12] 4A and 4B are side views showing the connecting portion between the connecting unit and the fixed wheel unit in the towing device, in which (a) shows the support arm in a locked state, and (b) shows the support arm in an unlocked state. [Figure 13] FIG. 2 is a front view of the fixed wheel unit in the towing device, in which (a) shows the device traveling straight ahead and (b) shows the device turning. [Figure 14] 10 is an explanatory diagram of the operation when the traction device is used to tow a traction vehicle, and is a layout diagram showing the vicinity of a preset placement position of the traction vehicle. FIG. [Figure 15] 13(a) to 13(d) are diagrams for explaining the operation when the traction device tows a cart, and are side views showing the operation of a coupling unit. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. 1 and 2, the towing device 10 of this embodiment is a device that is attached to a moving body 11 and tows a dolly 13 with casters 14 at the rear of the moving body 11. The moving body may of course be operated by a person, but the moving body 11 of the embodiment described below is sufficient as long as it can automatically travel unmanned on a road surface 15 and can move unmanned along a route set for transporting the dolly 13 or by remote control, and is configured to automatically control forward movement, backward movement, acceleration, deceleration, turning, turning, etc., so that unmanned travel can be performed.

[0016] The unmanned mobile body 11 of this embodiment has the shape of a handcart with a handle 11b provided at the rear of the main body 11a, and has a structure capable of automatic travel with a drive mechanism, a control mechanism, etc. provided on the main body 11a. On the other hand, the towed object is a cart 13 having casters 14 as wheels, such as a basket cart or slim cart. In this embodiment, all the wheels of the cart 13 that come into contact with the road surface 15 are made of casters 14.

[0017] As shown in Figures 3(a) and (b), the towing device 10 comprises a support unit 21 fixed to the rear of the unmanned mobile body 11, a coupling unit 22 supported by the support unit 21 so as to protrude rearward of the unmanned mobile body 11 and capable of coupling and uncoupling the trolley 13, and a fixed wheel unit 23 coupled to the coupling unit 22.

[0018] The support unit 21 comprises a mounting part 24 mounted to the rear of the unmanned mobile body 11, and a link mechanism part 25 that supports the connecting unit 22 relative to the mounting part 24 so that the connecting unit 22 can protrude and contract. The mounting part 24 is provided with a swinging connecting part 26 that connects the mobile body 11 and the link mechanism part 25 so that the mobile body 11 and the link mechanism part 25 can rotate relative to each other relative to each other, so that the trolley 13 can swing freely relative to the mobile body 11 when the traction device 10 is towing the traction device 10, as shown in Figures 4(a) and (b).

[0019] As shown in Figures 3(a)(b) and 5(a)(b), the swingable connecting part 26 has upper and lower shaft support parts 28 fixed to the main body part 11a and the handle 11b of the unmanned vehicle 11 via supports 27, and a connecting shaft 29 rotatably supported by the upper and lower shaft support parts 28 and arranged along the vertical direction. A connecting cylinder part 31 into which the connecting shaft 29 is loosely fitted so as to be rotatable relative to the shaft support part 28 is provided in the shaft support part 28, and the connecting shaft 29 is arranged to pass through it. The connecting shaft 29 is made of a hollow pipe material, and the link mechanism part 25 is connected to the upper end thereof.

[0020] A cam mechanism 32 is provided on the swingable connecting portion 26 for automatically positioning the link mechanism portion 25, which is swingably supported, at a predetermined swing position. As shown in Figures 5(a)(b) and 6, the cam mechanism 32 has a cylindrical cam 33 provided on the end of the connecting cylinder portion 31 of the upper shaft support portion 28, a cam follower 35 protruding radially from the outer circumferential surface of the connecting shaft 29 and arranged so as to be displaceable in the axial direction by an elongated hole 34, and a cam biasing means 36 arranged inside the connecting shaft 29 for biasing the cam follower 35 so as to press it against the cylindrical cam 33.

[0021] 6 and 7, the cam mechanism 32 is provided with a cam surface so that the cylindrical cam 33 is positioned at a predetermined position, specifically, the foremost position Pa along the central axis L1 in the front-rear direction of the movable body 11, and the upper end of the cam surface is located at the foremost position Pa. When the cylindrical cam 33 swings as shown in FIG. 5(b), the cam follower 35 in contact with the cam surface is displaced from the foremost position Pa, and the cam follower 35 biased by the cam biasing means 36 moves along the cam surface to the foremost position Pa, thereby rotating the connecting shaft 29. As a result, the link mechanism 25 is automatically positioned at a predetermined swing position, specifically, at a position along the central axis L1 in the front-rear direction of the dolly 13, as shown in FIG. 5(a).

[0022] 3(a) and (b), the link mechanism 25 is configured by a parallel link mechanism in which the mounting part 24 and the connecting unit 22 are connected by an upper arm 37a and a lower arm 37b. The link mechanism 25 can be extended and retracted by raising and lowering the connecting unit 22 relative to the mounting part 24, so that the connecting unit 22 can be extended and retracted relative to the unmanned mobile body 11 as shown in FIGS. 2(a) and (b).

[0023] The link mechanism 25 is also provided with a diagonal biasing means 38 for biasing the diagonal portions of the parallel link mechanism. The diagonal biasing means 38 biases the link mechanism 25 in a direction in which the link unit 22 is raised and the link mechanism 25 is contracted, as shown in FIG. 8. The diagonal biasing means 38 is set to an appropriate biasing force according to the weight of the link unit 22 and the fixed wheel unit 23, and is a biasing force capable of holding the link unit 22 and the fixed wheel unit 23 at an intermediate position between the most raised position and the most lowered position, as shown in FIG. 8. Therefore, when the link mechanism 25 is fully deployed and protruded and the dolly 13 is not connected to the link unit 22, the fixed wheel 53a is disposed in a floating state separated from the road surface 15, as shown in FIG. 3(b) and the like.

[0024] Furthermore, the link mechanism 25 is provided with a lock portion 41 that restricts rotation at each joint where the mounting portion 24 and the connecting unit 22 are connected to the upper arm and the lower arm when the link mechanism 25 is in the most contracted state and the most extended state, thereby preventing operation of the link mechanism 25. In this embodiment, as shown in Figures 9 and 10(a) to (c), the link mechanism 25 has a lock lever 42 that is provided on the connecting unit 22 so as to be slidable up and down, and a plurality of locking portions 43 that are provided near the fulcrum of the upper arm 37a and can be engaged with and disengaged from the lock lever 42.

[0025] When the link mechanism 25 is deployed and the lock lever 42 is engaged with one of the engagement parts 43 of the upper arm 37a as shown in FIG. 10(a), the connecting unit 22 is disposed in a protruding state as shown in FIG. 2(a). Between one of the engagement parts 43 and the lock lever 42, a clearance is provided that allows the fixed wheel 53a to move up and down between a position where the fixed wheel 53a contacts the road surface 15 and a position where the fixed wheel 53a is separated from the road surface 15. When the lock lever 42 is released as shown in FIG. 10(b), the link mechanism 25 can be contracted. When the lock lever 42 is engaged with the other engagement part 43 with the link mechanism 25 contracted as shown in FIG. 10(c), the connecting unit 22 is disposed in a most contracted storage state as shown in FIG. 2(b).

[0026] 11, the connecting unit 22 has a cart locking part 43 that can be engaged with and disengaged from the cart 13, a lifting drive part 44 that raises and lowers the cart locking part 43, and a relative position detection part 45 that detects the relative position between the cart locking part 43 and the cart 13. The cart locking part 43 has a locking part main body 46 that is substantially L-shaped in side view and has a bottom part and a side part, a front-rear direction locking part 47 that is provided at the bottom and chucks and locks a part of the cart 13 in the front-rear direction, and a vertical direction locking part 48 that is provided at the side and chucks and locks a part of the cart 13 in the up-down direction. The lifting drive part 44 is a linear actuator that drives the cart locking part 43 to lift and lower.

[0027] The relative position detection unit 45 detects the front-to-rear and up-down positions of the trolley 13 relative to the trolley engagement portion 43, and in this embodiment has a sensor that detects when the side of the trolley engagement portion 43 approaches or comes into contact with a part of the trolley 13 in the front-to-rear direction when the unmanned mobile body 11 retreats, and a sensor that detects when the bottom of the trolley engagement portion 43 approaches or comes into contact with a part of the trolley 13 in the top-to-bottom direction when the trolley engagement portion 43 rises. A detection signal detecting the front-rear proximity or contact with the trolley 13 is transmitted to a control unit (not shown), which stops the unmanned mobile body 11 from moving backward and drives the front-rear locking unit 47. The detection signal detecting the front-rear proximity or contact with the trolley 13 is also transmitted to a control unit (not shown) when the lifting drive unit 44 lifts the trolley locking unit 43, which stops the lifting drive unit 44 from lifting the trolley locking unit 43 and drives the up-down locking unit 48. In such a coupling unit 22, the lifting drive unit 44 presses the trolley locking unit 43 upward, and the trolley 13 is stably locked in a state where it is strongly pressed upward by the trolley locking unit 43.

[0028] 11(a) and (b), the fixed wheel unit 23 has a support arm 51 connected to the connecting unit 22 and extending rearward, a base portion 52 connected to the connecting unit 22 by the support arm 51 and to which a downward load from the connecting unit 22 is transmitted, and a fixed wheel pair 53 in which a plurality of fixed wheels 53a supported by the base portion 52 so as to be swingable left and right and rollable in the front-rear direction are arranged coaxially side by side. The support arm 51 is an arm extending from the connecting unit 22 so that the fixed wheel pair 53 can be arranged between the dolly 13 and the road surface 15. In this embodiment, in order to tow the dolly 13 with casters more stably, it is preferable that the fixed wheel unit 23 is configured to be arranged near the center of gravity of the dolly 13 connected to the connecting unit 22.

[0029] In this embodiment, the support arm 51 is connected to the connecting unit 22 so as to be able to expand and contract in the front-rear direction. As shown in Fig. 9, a locking section 54 for preventing the movement of the support arm 51 is provided at the connecting portion between the support arm 51 and the connecting unit 22, and is connected to a locking section 41 for preventing the movement of the link mechanism section 25. As shown in Figs. 12(a) and 12(b), the locking section 54 has an arm locking lever 55 provided to be able to swing near the fulcrum of the support arm 51, and a plurality of arm engaging sections 56 provided on the support arm 51 and able to engage and disengage with a claw 55a of the arm locking lever 55.

[0030] As shown in FIG. 12(a), when the claw 55a of the arm lock lever 55 is engaged with one of the arm engagement parts 56, the support arm 51 is held in a predetermined deployed position. As shown in FIG. 12(b), when the claw 55a of the arm lock lever 55 is released from the arm engagement part 56, the arm lock lever 55 becomes swingable. In this embodiment, by engaging the claw 55a of the arm lock lever 55 with the other arm engagement part 56, the support arm 51 can be held in a contracted state arranged in the vertical direction. As shown in FIG. 9, the arm lock lever 55 is connected to the lock lever 42 that regulates the operation of the link mechanism part 25 by a wire 55b or the like, and the arm lock lever 55 is also operated by operating the lock lever 42.

[0031] The base portion 52 is connected to the connecting unit 22 by the support arm 51, and is configured so that a reaction force generated when the carriage locking portion 43 of the connecting unit 22 strongly presses the carriage 13 upward to lock it is transmitted via the support arm 51. The base portion 52 has a fixed base 52a fixed to the support arm 51, a swinging base 52b supported so as to be swingable left and right on the fixed base 52a and supporting the fixed wheel pair 53 below the swing fulcrum, and a swing biasing means 57 consisting of a substantially V-shaped leaf spring interposed between the fixed base 52a and the swinging base 52 so as to keep the swinging base 52b in a neutral position.

[0032] As shown in Fig. 13(a), the fixed wheel pair 53 is integrated by coaxially arranging multiple fixed wheels 53a that can roll back and forth and fixing them to the oscillating base 52b. The multiple fixed wheels 53a are arranged symmetrically about an imaginary oscillating axis L2 that passes through the oscillating fulcrum 58 and extends in the front-rear direction. Therefore, when the oscillating base 52b oscillates relative to the fixed base 52a, the entire fixed wheel pair 53 oscillates about the oscillating axis 62. The oscillating base 52b and the fixed wheel pair 53 oscillate or fall relative to the fixed base 52a and are restored to a neutral position by the oscillating biasing means 57.

[0033] In such a fixed wheel unit 23, the fixed wheels 53a of the fixed wheel pair 53 are pressed against the road surface 15 by the downward load transmitted from the connecting unit 22 to the base part 52 via the support arm 51. While the dolly 13 is connected to the connecting unit 22 and moves straight on the flat road surface 15, the fixed wheels 53a roll against the road surface 15 with uniform contact pressure due to the load from the support arm. When centrifugal force is generated in the caster-equipped dolly 13 when turning while being towed, an outward force due to the centrifugal force is transmitted to the fixed base 52a of the base part 52 via the support arm 51 as shown in FIG. 13(b). This outward force applied to the fixed base 52a is applied to the swing fulcrum 58 of the swing base 52b. As a result, since the fixed wheel pair 53 supported by the oscillating base 52b is in contact with the road surface 15, the oscillating fulcrum 58 side of the fixed wheel pair 53 will attempt to oscillate in a direction in which it falls outward, and the fixed wheel 53a, which is positioned outside the oscillating fulcrum 58 and the oscillating axis L2, will attempt to increase the height from the fixed base 52a to the ground surface.

[0034] However, since the distance between the carriage locking portion 43 of the coupling unit 22 and the road surface 15 does not change whether the carriage is moving straight or turning, the height from the fixed base 52a to the ground surface does not increase, and the contact pressure of the fixed wheels 53a arranged on the outside against the road surface 15 increases accordingly, providing a so-called self-boosting effect. As a result, the outward frictional force obtained by the fixed wheel pair 53 can be increased in accordance with the centrifugal force generated in the carriage 13.

[0035] 11, the fixed wheel unit 23 of this embodiment is provided with an emergency stop lever 61 for stopping the traveling of the unmanned mobile body 11 when another object abuts against or approaches the unit. The emergency stop lever 61 is disposed across the entire width of the fixed wheel unit 23, rearward of all the fixed wheels 53a of the fixed wheel pair 53. By means of this emergency stop lever 61, a detection signal of abutment against or proximity to another object can be transmitted to, for example, the ECU of the unmanned mobile body 11, so that the traveling of the unmanned mobile body 11 can be stopped.

[0036] Next, the operation of towing the dolly 13 using such a towing device 10 will be described using an example of towing the dolly 13 placed in a preset position. First, as shown in Fig. 2(b), the link mechanism 25 and support arm 51 of the towing device 10 arranged in a contracted state at the rear of the dolly 13 are deployed, and locked by the lock lever 42 and arm lock lever 55, respectively, to prepare the towing device 10 in a state in which it protrudes rearward from the unmanned mobile body 11 as shown in Fig. 2(a). In this state, the unmanned mobile body 11 travels along a predetermined track, travels to a predetermined position where it will tow the dolly 13 as shown in Fig. 14, recognizes the position of the landmark 62, and stops. From this position, the unmanned mobile body 11 turns 90 degrees, and then moves back linearly to start the coupling operation.

[0037] At the stage at which the coupling operation starts, as shown in Fig. 15(a), the fixed wheel unit 23 is raised from the road surface 15 by the biasing force of the diagonal biasing means 38 of the link mechanism section 25. Also, as shown in Fig. 14, the coupling unit 22 is placed on the central axis L1 of the unmanned mobile body 11 by the cam mechanism 32 of the support unit 21. When the unmanned mobile body 11 moves backward in this state, as shown in Fig. 15(b), the relative position detection section 45 of the coupling unit 22 detects that the carriage locking section 43 and the carriage 13 have come close to or come into contact with each other in the front-rear direction, and the unmanned mobile body 11 stops moving backward.

[0038] 15(c), the bogie locking part 43 is raised by the drive of the lifting drive part 44, and the relative position detection part 45 of the coupling unit 22 detects that the bogie locking part 43 and the bogie 13 are close to each other or in contact with each other in the vertical direction, and the lifting drive part 44 stops lifting. At this time, the bogie is strongly pressed upward by the bogie locking part 43, and the lifting drive part 44 is held in this state. In this state, a part of the bogie 13 is locked by the bogie locking part 43 through the front-rear locking part 47 and the up-down locking part 48. As a result, as shown in FIG. 15(d), the bogie 13 is coupled to the coupling unit 22 of the towing device 10, and further, due to the reaction force of the bogie locking part 43 of the coupling unit 22 pressing a part of the bogie 13 upward, the support arm 51 is pressed down against the biasing force of the diagonal biasing means 57, and the fixed wheel pair 53 of the fixed wheel unit 23 is pressed against the road surface 15.

[0039] In this state, the moving body 11 is appropriately controlled to travel and tow the dolly 13. In the towing state, the swingable coupling portion 26 of the support unit 21 allows the coupling unit 22 to swing left and right relative to the moving body 11, and the multiple fixed wheels 53a can roll while being pressed against the road surface 15. Therefore, as shown in Figures 4(a) and (b), the moving body 11 can make the dolly 13 move straight and turn, so that the dolly 13 can be made to follow, and the dolly 13 can be transported from the starting point to the destination point.

[0040] 15(d) to 15(a), the dolly 13 is released from the coupling unit 22 by performing the reverse operation to that during towing at the destination point. Then, the fixed wheel 53a supported by the support arm 51 moves away from the road surface 15, and the coupling unit 22 is returned to a position on the central axis L1 of the mobile body 11 by the cam mechanism 32. Thereafter, when towing the next dolly 13, the dolly 13 can be towed by traveling to the starting point of the next dolly 13.

[0041] When the use of the towing device 10 is to be ended, as shown in Fig. 9, the handle of the connecting unit 22 is grasped and the lock lever 42 of the connecting unit 22 is gripped to release the engagement between the upper arm 37a of the link mechanism 25 and the engagement portion 43 of the lock lever 42, and also release the engagement between the claw 55a of the arm lock lever 55 and the arm engagement portion 56 of the support arm 51. In this state, the handle of the connecting unit 22 is pulled up. Then, as shown in Fig. 8, the link mechanism 25 of the support unit 21 contracts and the connecting unit 22 rises. Also, the support arm 51 is lowered from the fixed wheel pair 53 side by its own weight and contracts. At this time, since it is biased by the diagonal biasing means 38, the connecting unit 22 can be easily raised and contracted.

[0042] By lifting the connecting unit 22 to the upper end, the towing device 10 is contracted to the maximum extent as shown in Fig. 2(b). When the operation of the lock lever 42 is released in this state, the upper arm 37a of the link mechanism 25 is locked with the locking portion 43 of the lock lever 42, and the claw 55a of the arm lock lever 55 is locked with the arm locking portion 56 of the support arm 51. Therefore, the towing device 10 can be placed in the stored state at the rear of the mobile body 11, so that the operator can store the towing device 10 with a single action.

[0043] The effects of the towing device 10 described above will be described. According to the towing device 10 of this embodiment, the fixed wheels 53a that can roll in the front-rear direction are connected to the connection unit 22 that can connect and release the bogie 13, and the fixed wheels 53a are in contact with the road surface 15 in the connected state connected to the bogie 13. Therefore, when the moving body 11 travels while towing the bogie 13 with casters 14, the left-right movement of the bogie 13 connected by the connection unit 22 can be restricted by the fixed wheels 53a, and stable towing is possible. Since the connection unit 22 is supported so as to be swingable left-right with respect to the moving body 11, when the moving body 11 travels while towing the bogie 13 with casters 14 and traveling around a curve, the bogie 13 with casters 14, whose moving direction is restricted by the fixed wheels 53a, can be smoothly followed by the moving body 11.

[0044] On the other hand, in an open state where the dolly 13 is opened, the fixed wheels 53a are separated from the road surface 15, and the coupling unit 22 is positioned on the central axis L1, which is a predetermined swing position that is automatically set in advance for the unmanned mobile body 11. Therefore, if the coupling unit 22 is released after the dolly 13 is transported to the destination, the coupling unit 22 automatically returns to the central axis L1. As a result, in the open state, the coupling unit can always be positioned in the same position with respect to the unmanned mobile body 11, so that the coupling unit 22 can be easily coupled to an appropriate position of the dolly 13 to be transported next by the automatic travel of the unmanned mobile body 11.

[0045] In the towing device 10 of this embodiment, the support unit 21 has a swinging connection part 26 that is connected to the movable body 11 so that they can rotate relative to each other, and a cam mechanism 32 provided on the swinging connection part 26, so that the operation of automatically positioning the connection unit 22 on the central axis L1 can be easily achieved.

[0046] The oscillating connecting portion 26 has a connecting shaft 29 arranged along the vertical direction and a connecting tube portion 31 loosely fitted into the connecting shaft 29, and the cam mechanism 32 has a cylindrical cam 33 provided on the connecting tube portion 31 and a cam follower 35 protruding radially from the connecting shaft 29, arranged so as to be displaceable in the axial direction, and biased toward the cylindrical cam 33 portion. Therefore, a structure for automatically positioning the connecting unit 22 on the central axis L1 can be provided in a simple and compact structure without using a driving device.

[0047] When the support unit 21 has an attachment part 24 attached to the unmanned mobile body 11, a link mechanism part 25 that supports the connecting unit 22 relative to the attachment part 24 so that the connecting unit 22 can be extended and contracted, and a lock part 41 that prevents the link mechanism part 25 from operating when the link mechanism part 25 is contracted, when the unmanned mobile body 11 is not towing the traction device 10, the towing device 10 can be placed at the rear of the unmanned mobile body 11 in a compact contracted state, without interfering with the use of the unmanned mobile body 11 for other purposes.

[0048] When the link mechanism part 25 is a parallel link mechanism which raises and contracts the connecting unit 22 relative to the mounting part 24 and a diagonal biasing means 38 is provided which biases the diagonal space between the parallel link mechanism in a direction which raises the connecting unit 22, not only can the support unit 21 be arranged more compactly in a plan view when the towing device is not in use, but also, since the connecting unit 22 is biased in a direction which raises it by the diagonal biasing means 38, the support unit 21 can be contracted with less force.

[0049] At that time, since the fixed wheel 53a is configured to be positioned away from the road surface 15 in the open state by the biasing force of the diagonal biasing means 38, it is possible to separate the fixed wheel 53a from the road surface 15 in the open state without using a driving device and to ground the fixed wheel 53a on the road surface 15 in the connected state. Therefore, the structure of the support unit 21 of the connecting unit 22 can be realized with a simple configuration.

[0050] In the towing device 10 of this embodiment, the coupling unit 22 has the carriage locking portion 43, the lifting drive portion 44 for lifting and lowering the carriage locking portion 43, and the relative position detection portion 45 for detecting the relative position between the carriage locking portion 43 and the carriage 13, and the carriage locking portion 43 is lifted to press the carriage 13 upward and lock it, and the reaction force is applied to the fixed wheel 53a via the coupling unit 22, so that the fixed wheel 53a is grounded on the road surface 15. Therefore, in the coupled state, the load of the carriage 13 is used to press the fixed wheel 53a against the road surface 15, so that even if the carriage 13 is a heavy load, the fixed wheel 53a, which can roll back and forth, can be brought into contact with the road surface 15 with sufficient contact pressure, and the movement of the carriage 13 in the left and right direction during towing can be sufficiently restricted, and the carriage 13 with casters 14 can be stably towed.

[0051] The relative position detection unit 45 detects the front-rear approach position and the up-down approach position of the carriage locking unit 43 with respect to a part of the carriage 13, and when the carriage locking unit 43 has a front-rear direction locking unit 47 that locks a part of the carriage 13 in the front-rear direction and a up-down direction locking unit 48 that locks the part of the carriage 13 in the up-down direction, the moving body 11 travels backward to bring the coupling unit 22 closer to the carriage 13, and the carriage locking unit 43 can be easily locked and coupled in the front-rear direction and the up-down direction by the carriage locking unit 43 by raising the carriage locking unit 43 with the lifting drive unit 44. In addition, by releasing the locking by the carriage locking unit 43, lowering the lifting drive unit 44 and moving the unmanned moving body 11 forward, the towing device 10 can be easily detached from the carriage 13. Therefore, the towing device 10 can easily realize the coupling operation and the release operation of the carriage 13.

[0052] In the fixed wheel unit 23 of this embodiment, a plurality of fixed wheels 53a that can roll back and forth are arranged coaxially on the left and right of the swing axis L2 extending back and forth, and are supported integrally as a fixed wheel pair 53 so as to swing back and forth. Therefore, when the centrifugal force generated in the bogie 13 is transmitted from the connecting unit 22 to the fixed wheel unit 23, an outward force acts on the base part 52, and is loaded as an outward force on the swing fulcrum 58 that supports the fixed wheel pair 53 so as to be swingable. As a result, the contact pressure of the fixed wheels 53a arranged outside the swing axis L2 among the plurality of fixed wheels 53a against the road surface 15 increases, and the frictional force against the centrifugal force increases. Therefore, when the bogie 13 is towed by the unmanned mobile body 11, even if a centrifugal force is generated in the bogie 13 during turning, it is possible to prevent the bogie 13 from being significantly deviated outward from the running trajectory of the mobile body 11, and it is possible to tow the bogie 13 more stably.

[0053] In the towing device 10 of this embodiment, the fixed wheel unit 23 is connected to the connecting unit 22 by a support arm 51 extending forward and backward and can be positioned between the trolley 13 and the floor surface, so that the multiple fixed wheels 53 can be grounded on the road surface 15 below the trolley 13 connected to the connecting unit 22, and the caster-equipped trolley 13 can be towed stably.

[0054] When the base portion 52 has a fixed base 52a fixed to the support arm 51, a swinging base 52b supported so as to be freely swingable left and right on the fixed base 52a and supporting the fixed wheel pair 53 below the swing fulcrum, and a swing biasing means 57 for maintaining the swinging base 52b in a swing intermediate position, when centrifugal force is acting on the trolley 13, the contact pressure of the fixed wheels 53a arranged outside the swing axis L2 against the road surface 15 can be increased, and when centrifugal force is not acting on the trolley 13, the contact pressure of the multiple fixed wheels 53a against the road surface 15 can be easily restored to approximately equal levels.

[0055] The above embodiment can be modified as appropriate within the scope of the present invention. For example, in the above embodiment, an example of a device in which the fixed wheel 53a is positioned away from the road surface 15 when the connecting unit 22 is not connected to the trolley 13 is described, but this is not particularly limited, and the present invention can be applied in exactly the same way to a towing device that is used in a state in which the fixed wheel 53a is always in contact with the road surface 15. Although an example has been described in which the support unit 21 is configured to be expandable and contractable by the link mechanism 25, it may be configured to be grounded in a constantly protruding state on the movable body 11 without being expanded or contracted.

[0056] In the above embodiment, the traction device 10 of the present invention is described as a traction device in which all wheels that come into contact with the ground are made of casters 14. However, the traction device 10 of the present invention can tow a traction device in which some of the wheels, for example, a pair of front wheels or a pair of rear wheels, are made of fixed wheels. In this case, if the fixed wheels 53b of the traction device 10 are positioned away from the fixed wheels of the traction device in the traveling direction during towing, a deviation occurs between the trajectory along which the fixed wheels 53a of the traction device 10 move during turning and the trajectory along which the fixed wheels of the traction device 13 move, and the frictional force of the fixed wheels 53a of the traction device 10 tends to become a factor that impedes travel. In such a case, it is preferable to tow the traction device 13 in a state in which the fixed wheels 53a are separated from the road surface 15 by removing the force that pushes up the traction device 13 by the coupling unit 22, i.e., the force that pushes up the traction device 13 by the lifting drive unit 44. [Explanation of symbols]

[0057] 10 Traction device 11 Unmanned Vehicles 11a Main body 13 Trolley 14 Caster 15 Road surface 21 Support unit 22 Connecting Unit 23 Fixed wheel unit 24 Mounting part 25 Link mechanism 26 Swinging joint 27 Support 28 Shaft support part 29 Connecting shaft 31 Connecting cylinder part 32 Cam mechanism 33 Cylindrical Cam 34 long hole 35 Cam follower 36 Cam biasing means 37a Upper Arm 37b Lower Arm 38 Diagonal biasing means 41 Rock Section 42 Lock lever 43 Cart locking part 44 Lifting drive unit 45 Relative position detection unit 46 Locking part body 47 Front and rear locking part 48 Vertical locking part 51 Support arm 52 Base 52a Fixed base 52b Swing Base 53a Fixed wheel 53 Fixed wheel pair 54 Rock Section 55 Arm lock lever 55a Claw 56 Arm locking part 57 Swing biasing means 58 Swing fulcrum 61 Emergency stop lever L1 Central axis of the unmanned vehicle L2 Oscillation axis of the oscillation base

Claims

1. A towing device that is attached to a moving body and tows a caster-equipped dolly behind the moving body, A coupling unit capable of coupling and uncoupling the carriage; A fixed wheel unit is provided connected to the connecting unit and has a fixed wheel that can roll back and forth, The coupling unit has a carriage locking portion and a lifting drive portion that lifts and lowers the carriage locking portion, and the carriage locking portion can lock the carriage by pressing it upward, The fixed wheel unit includes a base portion to which a downward load is transmitted from the connecting unit, and a fixed wheel pair in which a plurality of the fixed wheels are coaxially arranged on the left and right of a swing axis supported by the base portion so as to be swingable left and right and extending forward and backward, A towing device, wherein a downward load from the coupling unit presses the plurality of fixed wheels against a road surface.

2. The towing device according to claim 1 , wherein the fixed wheel unit is connected to the coupling unit by a support arm extending forward and backward, and is disposed between the carriage connected to the coupling unit and the road surface.

3. 3. The towing device according to claim 2, wherein the base portion comprises a fixed base fixed to the support arm, a swing base supported by the fixed base so as to be swingable left and right about the swing axis and supporting the fixed wheel pair below the swing axis, and a swing biasing means for maintaining the swing base in a neutral position.

4. 4. A towing device according to claim 1, wherein all wheels of said dolly are casters.

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