Trolley unit and assembly method thereof

Abstract

To provide a trolley unit that is not easily restricted by the size of a towing trolley.SOLUTION: A trolley unit 100 is a trolley unit comprising a self-propelled running trolley 1 and a towing trolley 2 to be towed by the running trolley 1. The running trolley 1 has a first loading platform 10 capable of loading cargo, and the towing trolley 2 has a second loading platform 20 capable of loading cargo. The second loading platform 20 is positioned to cover the first loading platform 10 from above. The running trolley 1 and the towing trolley 2 are connected by fitting a protrusion 32 provided on one of an upper surface of the first loading platform 10 and a lower surface of the second loading platform 20 and a recess 36 provided on the other.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a bogie unit and a method for assembling the bogie unit. [Background technology]

[0002] There is known a technique for towing a dolly by a transport vehicle. For example, Patent Document 1 describes a technique for transporting a dolly having a loading platform by a transport vehicle equipped with a towing tool. This towing tool connects the transport vehicle and the dolly by guiding both the left and right side surfaces of the dolly with a pair of receiving parts protruding upward, pressing the front surface of the dolly with multiple forward-facing pressing parts, and pressing the rear surface of the dolly with a movable stopper. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2023-14790 A Summary of the Invention [Problem to be solved by the invention]

[0004] In the connection technology described in Patent Document 1, the carrier vehicle and the dolly are connected by surrounding and supporting the dolly with members arranged on the front, back, left and right sides, so there is a limit to the size of the dolly that can be connected. For this reason, Patent Document 1 cannot be said to be sufficient in terms of reducing the restrictions on the size of the dolly.

[0005] SUMMARY OF THE PRESENT INVETION The present invention has been made in consideration of the above problems, and an object of the present invention is to provide a bogie unit which is not subject to the size constraints of the towing bogie. [Means for solving the problem]

[0006] In order to solve the above problems, a cart unit according to one embodiment of the present invention is a cart unit including a self-propelled traveling cart and a towing cart towed by the traveling cart, the traveling cart having a first platform on which a load can be placed, and the towing cart having a second platform on which a load can be placed. The second platform is disposed so as to cover the first platform from above, and the traveling cart and the towing cart are connected by fitting a convex portion provided on one of an upper surface of the first platform and a lower surface of the second platform into a concave portion provided on the other of the first platform and the second platform.

[0007] Another aspect of the present invention is a method for assembling a bogie unit. This method is a method for assembling a bogie unit including a self-propelled traveling bogie having a first platform on which a load can be placed, and a towing bogie having a second platform on which a load can be placed and towed by the traveling bogie, in which the towing bogie has an enclosure member facing each of the four sides of the traveling bogie. A convex portion is provided on one of the upper surface of the first platform and the lower surface of the second platform, and a concave portion is provided on the other. This assembly method includes placing the towing bogie from above the traveling bogie, positioning the second platform above the first platform, and arranging the enclosure member so as to surround the four sides of the traveling bogie, and connecting the towing bogie to the traveling bogie by fitting the convex portion and the concave portion.

[0008] Any combination of the above components, or mutual substitution of the components or expressions of the present invention between methods, systems, etc. are also valid aspects of the present invention. Effect of the Invention

[0009] According to the present invention, it is possible to provide a bogie unit that is not subject to the restrictions imposed by the size of the towing bogie. [Brief description of the drawings]

[0010] [Figure 1] FIG. 2 is a perspective view illustrating an example of a carriage unit according to the embodiment. [Diagram 2] 2 is a side cross-sectional view showing a coupling mechanism of the carriage unit of FIG. 1. [Diagram 3] FIG. 2 is a plan view showing the surrounding member of the towing dolly of FIG. [Figure 4] FIG. 2 is a perspective view showing the traveling carriage of FIG. 1. [Diagram 5] FIG. 2 is a diagram showing the arrangement of wheels of the traveling carriage of FIG. 1. [Figure 6] FIG. 2 is a block diagram illustrating a schematic configuration of the carriage unit of FIG. [Figure 7] FIG. 13 is a side cross-sectional view showing a modified example equipped with a reciprocating mechanism. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] The present invention will be described below based on preferred embodiments with reference to the drawings. In the embodiments and modified examples, the same or equivalent components and members are given the same reference numerals, and duplicated descriptions are omitted as appropriate. The dimensions of the members in each drawing are enlarged or reduced as appropriate for ease of understanding. Some of the members that are not important for explaining the embodiments are omitted in each drawing.

[0012] In addition, terms including ordinal numbers such as first, second, etc. are used to describe various components, but these terms are used only for the purpose of distinguishing one component from another component, and the components are not limited by these terms.

[0013] [Embodiment] The configuration of the bogie unit 100 according to the embodiment will be described with reference to the drawings. Fig. 1 is a perspective view showing an example of the bogie unit 100. As indicated by the arrows in Fig. 1, the straight-ahead direction of the bogie unit 100 is referred to as "front" and "forward", the opposite direction is referred to as "rear" and "rear", the rightward direction of the straight-ahead direction is referred to as "right" and "rightward", and the opposite direction is referred to as "left" and "leftward".

[0014] The cart unit 100 is a cart unit equipped with a self-propelled traveling cart 1 and a towing cart 2 towed by the traveling cart 1. The traveling cart 1 has a first platform 10 on which a load can be placed, and the towing cart 2 has a second platform 20 on which a load can be placed. The cart unit 100 is a cart unit capable of placing an object (not shown) on the second platform 20 and transporting it to a destination.

[0015] 1, the towing cart 2 in a separated state before coupling is shown by a solid line, and the outline of the towing cart 2 after coupling is shown by a dashed line. The traveling cart 1 of the embodiment also functions as an unmanned guided vehicle that can load an object (not shown) on the first platform 10 by itself and transport it to a destination.

[0016] The towing dolly 2 of the embodiment mainly includes a second platform 20, four legs 21, four wheels 22, four enclosing members 58, and a second connecting member 34. The second connecting member 34 will be described later.

[0017] In the embodiment, the second mounting table 20 is a mounting table that is rectangular in plan view and is made of pipe material such as a rectangular pillar. The second mounting table 20 includes an outer periphery pipe material in which pipe materials are combined on four sides, and a plurality of pipe materials that are arranged in a lattice shape between the pipe materials on two sides spaced apart from each other in the front and rear.

[0018] The legs 21 are made of, for example, a pipe material such as a cylinder, and extend downward from the four corners of the first mounting table 10. The four corners of the second mounting table 20 are fixed to the legs 21 and supported by the legs 21. The wheels 22 are driven wheels fixed to the lower ends of the legs 21, and smoothly support the horizontal movement of the towing cart 2. The wheels 22 may be, for example, swivel casters. In this case, the towing cart 2 can be smoothly moved along the traveling direction of the traveling cart 1.

[0019] The second mounting table 20 is disposed so as to cover the first mounting table 10 from above. At this time, the traveling cart 1 and the towing cart 2 are connected by a connecting mechanism 30. The connecting mechanism 30 has a convex portion 32 provided on one of the upper surface of the first mounting table 10 and the lower surface of the second mounting table 20 and a concave portion 36 provided on the other, and connects the traveling cart 1 and the towing cart 2 by fitting the convex portion 32 and the concave portion 36 together. In the embodiment, the convex portion 32 is provided on the lower surface of the second mounting table 20, and the concave portion 36 is provided on the upper surface of the first mounting table 10.

[0020] In the coupled state, the wheels 14 of the traveling dolly 1 and the wheels 22 of the towing dolly 2 are in contact with the floor surface (not shown), and the second platform 20 is separated upward from the first platform 10. At this time, the coupling mechanism 30 and the towing dolly 2 are configured so that most of the gravitational load of the luggage placed on the second platform 20 is transmitted to the wheels 22 of the towing dolly 2, and the first platform 10 is hardly subjected to the gravitational load received by the second platform 20. The coupling mechanism 30 and the towing dolly 2 may be configured so that a part of the gravitational load of the luggage placed on the second platform 20 is transmitted to the wheels 14 of the traveling dolly 1 via the first platform 10.

[0021] Fig. 2 is a side cross-sectional view showing the coupling mechanism 30 of the cart unit 100. The coupling mechanism 30 is a mechanism for coupling the traveling cart 1 and the towing cart 2, and has a first coupling member 38, a recess 36, a second coupling member 34, and a rod-shaped member 33. Fig. 2(A) shows a case where the protrusion 32 is provided on the lower surface of the second mounting table 20 and the recess 36 is provided on the upper surface of the first mounting table 10, and Fig. 2(B) shows a case where the recess 36 is provided on the lower surface of the second mounting table 20 and the protrusion 32 is provided on the upper surface of the first mounting table 10. The configuration of Fig. 2(A) will be described below as an example.

[0022] The traveling cart 1 has one or more first connecting members 38 that are detachably attached to the upper surface of the first mounting platform 10, and the first connecting members 38 have a recess 36. The recess 36 in this example is a blind hole. The towing cart 2 has one or more second connecting members 34 that are detachably attached to the lower surface of the second mounting platform 20, and the second connecting members 34 have a protrusion 32. The one or more recesses 36 are provided in the same number as the one or more protrusions 32, at positions corresponding to the one or more protrusions 32.

[0023] The shapes of the first connecting member 38 and the second connecting member 34 are not particularly limited. In the embodiment, as shown in FIG. 1, the first connecting member 38 is a rectangular band-shaped member whose longitudinal direction extends left and right in a plan view. In the embodiment, as shown in FIG. 1, the second connecting member 34 is a rectangular band-shaped member whose longitudinal direction extends left and right in a plan view. In the embodiment, the first connecting member 38 and the second connecting member 34 are provided at two locations on either side of the turning center CL of the traveling carriage 1. That is, the recessed portion 36 and the protruding portion 32 are provided at two locations on either side of the turning center CL of the traveling carriage 1. In this case, the rotation of the towing carriage 2 relative to the traveling carriage 1 can be restricted. When three or more recessed portions 36 and protruding portions 32 are provided, the recessed portions 36 and the protruding portions 32 can be arranged so as to surround the turning center CL. From the viewpoint of evenly sharing the connection load, it is desirable that the multiple recessed portions 36 and the protruding portions 32 are each arranged at an equal distance from the turning center CL.

[0024] The fixing method of the first connecting member 38 is not particularly limited. In the embodiment, the first connecting member 38 is fixed to a tapped hole 37 provided on the upper surface of the first mounting table 10 by using a bolt B1. The bolt B1 is screwed into the tapped hole 37 through a through hole 39 formed in the first connecting member 38. In the embodiment, the first connecting member 38 is fixed by the bolt B1 at two points across the recess 36, but may be bolted at three or more points. The fixing method of the second connecting member 34 is not particularly limited, but in the embodiment, the second connecting member 34 is fixed by using a bolt B2 to a tapped hole (not shown) provided on the lower surface of the second mounting table 20. The bolt B2 is screwed into the tapped hole through a through hole 342 formed in the second connecting member 34. In the embodiment, the second connecting member 34 is fixed by the bolt B2 at two points across the protrusion 32, but may be bolted at three or more points.

[0025] The tapped hole 37 may be provided exclusively for fixing the first connecting member 38, but in the embodiment, it is also used for fixing other types of attachment members (not shown). That is, a general-purpose designed unmanned guided vehicle can be used as the traveling carriage 1. In this case, it is advantageous for reducing design man-hours, and the number of manufacturing man-hours can be reduced compared to the case where a dedicated tapped hole is provided.

[0026] The first mounting table 10 has tap holes 37 provided in advance for mounting at least two types of attachment members. The first mounting table 10 may be one of the attachment members of the first mounting table 10. In addition to the first connecting member 38, the attachment member may be a guide member for a load to be placed on the first mounting table 10, or a hook for hanging a rope for fixing the load. In the embodiment, eight tap holes 37 are provided in the first mounting table 10, and each of the first connecting members 38 uses two of the eight tap holes 37. The number of tap holes 37 is not particularly limited.

[0027] As shown in FIG. 2, the protrusion 32 protrudes downward from the second connecting member 34. The second connecting member 34 and the protrusion 32 are formed separately and then combined. The protrusion 32 is a tip portion of a rod-shaped member 33 inserted into a through hole 35 provided in the second connecting member 34. A flange 31 larger than the through hole 35 is provided on the base end side of the rod-shaped member 33. The flange 31 regulates the vertical position of the protrusion 32. The rod-shaped member 33 has a hollow portion 334 that opens upward. The rod-shaped member 33 is fixed to the second connecting member 34 by press-fitting, bonding, welding, or the like. The tip of the protrusion 32 is conical to facilitate insertion into the recess 36.

[0028] If the protrusion 32 is significantly displaced during normal use, the connection state of the connection mechanism 30 becomes unstable, and the connection may come off. Therefore, in the embodiment, the protrusion 32 is provided on the second mounting table 20 so as to be non-displaceable. Non-displaceable means that the protrusion 32 does not shift or become displaced even if a person applies force to the protrusion 32 without using tools. Specifically, the rod-shaped member 33 having the protrusion 32 is fixed to the second connecting member 34 that is bolted to the second mounting table 20, so that the protrusion 32 is firmly supported by the second mounting table 20 during normal use and is provided so as not to shift its position. Note that when the protrusion is provided on the first mounting table, the protrusion is provided on the first mounting table so as not to be displaceable. Also, in the case of FIG. 2(B), the rod-shaped member 33 may be fixed to the upper surface of the first connecting member 38 without penetrating the first connecting member 38.

[0029] The surrounding member 58 of the towing dolly 2 will be described with reference to Figs. 1 and 3. Fig. 3 is a plan view showing the surrounding member 58 of the towing dolly 2. If the coupling mechanism 30 is unintentionally disconnected, only the traveling dolly 1 will travel, and the towing dolly 2 may be left behind. In this case, the travel of all dollies in the area will be stopped, and a worker will perform a recovery operation to return them to the connected state, during which the transportation operation will be interrupted. Therefore, in the embodiment, the towing dolly 2 has the surrounding member 58 facing each of the four sides of the traveling dolly 1. In this case, even if the coupling mechanism 30 is disconnected, the traveling dolly 1 can continue to tow by pushing the surrounding member 58.

[0030] In this embodiment, the surrounding member 58 is made of, for example, a pipe material such as a cylinder extending substantially horizontally, and is bridged between two adjacent leg portions 21. Both ends of the surrounding member 58 are fixed to the leg portions 21. As shown in Fig. 3, the surrounding members 58 are assembled in a quadrangle so as to surround the towing cart 2 in a plan view. The surrounding members 58 are provided at a position that is not in a blind spot of a sensor mounted on the traveling cart 1, which will be described later.

[0031] The traveling cart 1 will be described with reference to Fig. 4, Fig. 5, and Fig. 6. Fig. 4 is a perspective view showing the traveling cart 1. Fig. 5 is a diagram showing the arrangement of wheels of the traveling cart 1. Fig. 6 is a block diagram showing a schematic configuration of the cart unit 100.

[0032] As an example, the traveling cart 1 may be an autonomous mobile robot (AMR) that autonomously travels to a destination. The traveling cart 1 of the embodiment can generate a travel route from a starting point to a destination and travel autonomously along the generated route. The autonomous travel of the traveling cart 1 can be realized by using an autonomous travel technology based on a known principle. As an example, the traveling cart 1 of the embodiment travels autonomously using a control technology called SLAM (Simultaneous Localization and Mapping).

[0033] Since SLAM is a well-known technology, detailed description will be omitted. SLAM can simultaneously perform the self-location function of the traveling cart 1 and the map creation function. The map creation function is a function that acquires surrounding information about what is around through an imaging means or an on-board sensor, and creates map information, which is a map of the surrounding area, based on this surrounding information. The self-location function is a function that compares the map information with stored data about previously stored locations, and identifies the self-location and self-direction on the map if the stored data and map information match. The traveling cart 1 can calculate the distance between itself and obstacles, landmarks, etc. in the vicinity using SLAM, and control its traveling so as to avoid obstacles based on the calculation results.

[0034] The traveling cart 1 of the embodiment includes a car body 12, a plurality of wheels 14A to 14D, a wheel drive unit 16, an operation unit 17, a battery (not shown), a first mounting base 10, an object detection sensor 11, an obstacle sensor 19, an image sensor 18, and an information processing unit 40. The object detection sensor 11, the obstacle sensor 19, and the image sensor 18 are collectively referred to as mounted sensors. The car body 12 functions as an outer shell that surrounds the components housed therein.

[0035] The operation unit 17 accepts input information based on a user's operation, and provides the input information to the information processing unit 40. The operation unit 17 accepts input of information related to the user's driving, such as a destination, and provides the result to the information processing unit 40.

[0036] As shown in FIG. 4, the wheels 14A to 14D are attached inside the vehicle body 12 so that a part of the wheel protrudes downward from the vehicle body 12. The wheels 14A to 14D are not limited in configuration, but in the embodiment, as shown in FIG. 5, the wheels 14A to 14D include two first wheels 14A, two second wheels 14B, two third wheels 14C, and two fourth wheels 14D. The two first wheels 14A are driving wheels driven by the wheel driving unit 16, and are arranged at a distance from each other on the left and right near the front-rear center. The two second wheels 14B are driven wheels, and are arranged at a distance from each other on the left and right in front of the first wheel 14A. The two third wheels 14C are driven wheels, and are arranged at a distance from each other on the left and right in front of the second wheel 14B. The two fourth wheels 14D are driven wheels, and are arranged at a distance from each other on the left and right behind the first wheel 14A.

[0037] The wheel drive unit 16 drives and rotates the two first wheels 14A based on the control of the information processing unit 40. The wheel drive unit 16 of this embodiment includes two gear motors (not shown) corresponding to the two first wheels 14A, respectively. The wheel drive unit 16 may include a known drive device such as a motor or an engine, instead of the gear motor. The traveling cart 1 moves forward or backward when the two first wheels 14A are driven and rotated at the same speed, and turns right or left around the turning center CL when a speed difference is generated between the two first wheels 14A.

[0038] The battery supplies power to the wheel drive unit 16, the object detection sensor 11, the obstacle sensor 19, the image sensor 18, and the information processing unit 40. The battery in this embodiment is a lithium ion battery. Instead of a lithium ion battery, the battery may include a secondary battery based on a known principle.

[0039] The first mounting table 10 is a plate-like member attached onto the vehicle body 12 so as to cover the upper side of the vehicle body 12. The first mounting table 10 of the embodiment has a substantially rectangular outer shape that is substantially the same as the outer shape of the vehicle body 12 in a plan view.

[0040] The object detection sensor 11 detects an object outside the vehicle body 12, and provides the detection result to the information processing unit 40. The information processing unit 40 creates a map based on the detection result of the object detection sensor 11. During autonomous driving, the information processing unit 40 specifies the vehicle's own position on the map based on the detection result of the object detection sensor 11. In the embodiment, the object detection sensor 11 is provided on each of the front, rear, left and right surfaces of the vehicle body 12. Fig. 4 shows only the object detection sensors 11 arranged on the front and left surfaces.

[0041] The object detection sensor 11 is a sensor capable of detecting an object within a detection range by receiving reflected light of detection light projected by the object detection sensor 11 toward the outside of the vehicle body. As an example, the object detection sensor 11 projects detection light in a range that spreads radially from the object detection sensor 11 as a center between the vehicle body 12 and the first mounting table 10. As an example, the object detection sensor 11 of the embodiment is a LiDAR (Light Detection And Ranging).

[0042] The obstacle sensor 19 detects obstacles outside the vehicle body 12 and provides the detection results to the information processing unit 40. The information processing unit 40 controls the traveling of the traveling carriage 1 so as to avoid the obstacles based on the detection results of the object detection sensor 11 and the obstacle sensor 19 during autonomous traveling. In the embodiment, three obstacle sensors 19 are arranged on the front of the vehicle body 12, one on each of the left and right sides. FIG. 4 shows only one obstacle sensor 19 arranged on the front. For example, the obstacle sensor 19 is an optical sensor, and the optical axis of the detection light is oriented 5 degrees upward from the horizontal plane.

[0043] The image sensor 18 detects guide marks attached to fixtures, accessories, etc., such as floors, ceilings, walls, and shelves, and provides the detection results to the information processing unit 40. The guide marks in the embodiment include lines formed on the floor surface and two-dimensional markers such as two-dimensional codes. The image sensor 18 in the embodiment is a camera having a lens (not shown) and an image sensor (not shown), and is attached to the front of the vehicle body 12. When creating a map, the information processing unit 40 stores the detection results of the image sensor 18 as reference data corresponding to the map. During autonomous driving, the information processing unit 40 compares the detection results of the image sensor 18 with the stored reference data, and uses the comparison results to identify the vehicle's own position on the map.

[0044] The information processing unit 40 will now be described. Each functional block of the information processing unit 40 shown in Fig. 6 can be realized in terms of hardware by elements such as a computer processor, CPU, and memory, electronic circuits, and mechanical devices, and in terms of software by a computer program, etc., but here, functional blocks realized by cooperation between them are depicted. Therefore, it will be understood by those skilled in the art that these functional blocks can be realized in various forms by combining hardware and software.

[0045] The information processing unit 40 includes an input unit 41, a route generating unit 42, a map generating unit 44, a self-location identifying unit 45, a driving control unit 46, a storage unit 47, and a communication unit 48. These functional blocks can exchange information with each other via an information transmission path 43 such as a data bus.

[0046] The input unit 41 acquires the detection results of the mounted sensors and the input information of the operation unit 17. The route generation unit 42 generates a travel route to the destination. The starting point of the travel route may be the current location or a separately set location. The starting point and the destination may be input by the user via the operation unit 17, or may be input from the upper controller 60 via the communication unit 48. In this specification, the upper controller 60 includes a computer system and a mobile information terminal such as a smartphone or a tablet terminal.

[0047] When creating a map, the map generation unit 44 creates a map based on the detection results of the mounted sensors acquired by the input unit 41. During autonomous driving, the map generation unit 44 corrects the map based on the detection results of the mounted sensors acquired by the input unit 41.

[0048] The self-position identifying unit 45 identifies the self-position on the map based on the detection result of the mounted sensor during autonomous driving. The driving control unit 46 controls the wheel drive unit 16 so as to travel on the generated route based on the identified self-position during autonomous driving. The storage unit 47 stores the information inputted by the input unit 41, the map generated by the map generating unit 44, the route generated by the route generating unit 42, the identified self-position, etc. The communication unit 48 transmits and receives information to and from an external device such as the upper controller 60 via a wireless or wired communication line.

[0049] Next, a method for assembling the cart unit 100 will be described. This assembly method includes placing the towing cart 2 over the traveling cart 1, positioning the second mounting table 20 above the first mounting table 10, arranging the surrounding members 58 to surround the four sides of the traveling cart 1, and connecting the towing cart to the traveling cart by fitting the convex portions 32 and the concave portions 36 together.

[0050] The traveling operation of the thus assembled cart unit 100 will be described. As an example, the cart unit 100 starts traveling when it receives a command to start the operation. This operation is mainly controlled by the information processing unit 40 of the traveling cart 1.

[0051] First, the information processing unit 40 generates a travel route to the destination of the traveling vehicle 1. At this time, the information processing unit 40 receives information on the starting point and destination and related information from the upper controller 60 via the communication unit 48. The information processing unit 40 generates the travel route based on information on the destination, etc. The operation of generating the travel route can be realized by the above-mentioned SLAM technology.

[0052] Next, the information processing unit 40 causes the traveling vehicle 1 to travel along the travel route, and when the traveling vehicle 1 arrives at the destination, stops the traveling of the traveling vehicle 1. At this time, the towing vehicle 2 towed by the traveling vehicle 1 also arrives at the destination.

[0053] The features of the cart unit 100 according to this embodiment will be described. The cart unit 100 is a cart unit including a self-propelled traveling cart 1 and a towing cart 2 towed by the traveling cart 1. The traveling cart 1 has a first platform 10 on which a load can be placed, and the towing cart 2 has a second platform 20 on which a load can be placed, the second platform 20 being disposed so as to cover the first platform 10 from above, and the traveling cart 1 and the towing cart 2 are connected by fitting a convex portion 32 provided on one of the upper surface of the first platform 10 and the lower surface of the second platform 20 with a concave portion 36 provided on the other.

[0054] According to this configuration, the traveling bogie 1 can be towed by connecting it to the towing bogie 2 that is shaped to cover the traveling bogie 1, so it can be connected to multiple types of towing bogies 2 of different sizes and is less restricted by the size of the towing bogie 2. Since the range of application of a single traveling bogie 1 is expanded, the utilization efficiency of the traveling bogie 1 is increased compared to a case where a different size of traveling bogie 1 is prepared for each size of the towing bogie 2. In addition, since the number of types of traveling bogies 1 is reduced, the manufacturing costs of the traveling bogies 1 can be suppressed. Also, compared to a configuration in which the towing bogies 2 are connected laterally, the freedom of the traveling route is increased and it can be used in a narrow space.

[0055] Above, examples of the embodiments of the present invention have been described in detail. The above-mentioned embodiments merely show specific examples of implementing the present invention. The contents of the embodiments do not limit the technical scope of the present invention, and many design changes such as changes, additions, and deletions of components are possible within the scope of the invention as defined in the claims. In the above-mentioned embodiments, the contents for which such design changes are possible are described with notations such as "of the embodiment" and "in the embodiment", but design changes may also be permitted for contents without such notations. In addition, hatching in the drawings does not limit the material of the hatched object.

[0056] [Variations] The following describes the modified examples. In the drawings and description of the modified examples, the same or equivalent components and members as those in the embodiment are denoted by the same reference numerals. Descriptions that overlap with the embodiment will be omitted as appropriate, and the description will focus on configurations that differ from the embodiment.

[0057] In the above description, an example in which the convex portion 32 and the concave portion 36 do not advance or retreat has been shown, but the present invention is not limited to this. One or both of the convex portion 32 and the concave portion 36 may be configured to advance and retreat. FIG. 7 is a side cross-sectional view showing a modified connecting mechanism 30 having an advance and retreat mechanism 56. In the modified example, the connecting mechanism 30 has an advance and retreat mechanism 56 that advances and retreats the concave portion 36. The advance and retreat mechanism 56 retreats the concave portion 36 when not connected and advances it when connected based on the user's operation. In the example of FIG. 7, the advance and retreat mechanism 56 is a hydraulic cylinder that advances and retreats the concave portion 36 up and down. Instead of a hydraulic cylinder, the advance and retreat mechanism 56 can employ a known advance and retreat mechanism such as a parallel link mechanism or a cam mechanism driven by a motor (not shown). The connecting mechanism 30 may be configured to advance and retreat the convex portion 32.

[0058] In the above description, an example in which the second mounting table 20 has one stage is shown, but the present invention is not limited to this. The second mounting table may have multiple stages.

[0059] In the above description, an example was given in which the recess 36 was a blind hole, but the present invention is not limited to this. For example, the recess may be a through hole.

[0060] In the above description, an example in which the second mounting table 20 is separated from the first mounting table 10 in the connected state has been shown, but the present invention is not limited to this. In the connected state, the second mounting table may be in contact with the first mounting table 10.

[0061] In the above description, an example has been shown in which the protrusion 32 and the second connecting member 34 are formed separately, but the present invention is not limited to this. For example, the protrusion may be formed integrally with the second connecting member.

[0062] In the above description, an example has been given in which the surrounding member 58 is a pipe material extending substantially horizontally, but the present invention is not limited to this. For example, the surrounding member may be in a shape other than a pipe shape, such as a plate shape, a string shape, a net shape, a lattice shape, a cloth shape, a film shape, or a combination of these shapes. For example, the surrounding member may be configured to extend in a direction other than the horizontal direction, such as a vertical direction or an oblique direction, or may be configured to combine these shapes.

[0063] In the above description, the traveling cart 1 has four side surfaces and is configured to be a rectangle in plan view, but is not limited thereto and may be various shapes such as a circle or a triangle in plan view. In this case, the enclosing member 58 may be configured according to the shape of the traveling cart 1. Also, the enclosing member 58 may not be provided, and the enclosing member 58 may not face some of the side surfaces of the traveling cart 1.

[0064] Each of these modified examples provides the same functions and effects as the embodiment.

[0065] Any combination of the above-described embodiments and modifications is also useful as an embodiment of the present invention. A new embodiment resulting from the combination has the combined effects of the respective embodiments and modifications. [Explanation of symbols]

[0066] 1 traveling bogie, 2 towing bogie, 10 first mounting base, 20 second mounting base, 32 convex portion, 34 second connecting member, 36 concave portion, 37 tapped hole, 38 first connecting member, 100 bogie unit.

Claims

1. A bogie unit including a self-propelled traveling bogie and a towing bogie to be towed by the traveling bogie, The traveling carriage has a first platform on which a load can be placed, The towing dolly has a second platform on which a load can be placed, the second stage is disposed so as to cover the first stage from above, The running cart and the towing cart are connected to a cart unit by engaging a convex portion provided on one of the upper surface of the first mounting table and the lower surface of the second mounting table with a concave portion provided on the other.

2. The cart unit according to claim 1 , further comprising a first connecting member detachably attached to an upper surface of the first mounting table and having the recess.

3. the first mounting table has tapped holes provided in advance for mounting at least two types of attachment members; The bogie unit according to claim 2 , wherein the first connecting member is fixed to the tapped hole by a bolt.

4. The carriage unit according to claim 1 , wherein the protrusion is provided on the first mount table or the second mount table so as to be unable to be displaced.

5. The bogie unit according to claim 1 , wherein the protruding portion and the recessed portion are provided at a plurality of positions on either side of a turning center of the traveling bogie.

6. The truck unit according to claim 1 , wherein the towing truck has surrounding members facing each of four sides of the traveling truck.

7. The carriage unit according to claim 1 , further comprising an advancing / retracting mechanism for advancing or retracting the convex portion or the concave portion.

8. A method for assembling a carriage unit including a self-propelled traveling carriage having a first platform on which a load can be placed, and a towing carriage having a second platform on which a load can be placed and towed by the traveling carriage, comprising: The towing cart has an enclosure member facing each of the four side surfaces of the traveling cart, a convex portion is provided on one of an upper surface of the first mounting table and a lower surface of the second mounting table, and a concave portion is provided on the other of the upper surface and the lower surface of the second mounting table; This assembly method includes: placing the towing dolly from above the traveling dolly; positioning the second mounting table above the first mounting table; and arranging the surrounding member to surround four sides of the traveling dolly; An assembly method in which the towing cart is connected to the traveling cart by engaging the convex portion with the concave portion.

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