Transport vehicles, rails, and material transport systems in manufacturing plants
By using horizontal and vertical steering wheels in the steering unit of the transport vehicle to contact the guide rail, the vibration and impact problems during the branch are solved, and a more stable driving path is achieved.
Patent Information
- Application Number
- CN202111160549.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Priority Date
- 2020-10-06
- Filing Date
- 2021-09-30
- Publication Date
- 2024-12-17
- Estimated Expiration
- 2041-09-30
AI Technical Summary
In semiconductor manufacturing plants, vibration and impact are easily generated when transporting vehicles are branches in the driving path, affecting their smooth driving.
A steering unit including a horizontal steering wheel and a vertical steering wheel is designed, which can contact the vertical and horizontal guide rails in the branch of the traveling track, and through the vertical and horizontal main body of the moving body, it ensures that the vehicle is more stable in the branch direction. Drive to reduce shock and vibration.
It realizes smooth driving in the branches, reduces vibration and impact, and improves the operating stability and efficiency of the transported vehicle.
Smart Images
Figure CN114380005B_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to an article transport system in a manufacturing plant, and more particularly to a transport vehicle, a track, and an article transport system capable of traveling more smoothly on a branch portion. Background Art
[0002] Semiconductor (or display) manufacturing processes are processes for manufacturing semiconductor elements on substrates (e.g., wafers), including exposure, evaporation, etching, ion implantation, cleaning, packaging, etc. A manufacturing plant for manufacturing semiconductor elements is composed of one or more clean rooms, and manufacturing equipment for performing semiconductor manufacturing processes is arranged on each floor.
[0003] In order to maximize the efficiency of the semiconductor manufacturing process, not only methods for improving each semiconductor manufacturing process are introduced, but also means for quickly and efficiently transporting items (for example, substrates) between various manufacturing equipment are introduced. Representatively, an OHT (overhead hoist transport) system is used to transport items along a path set on the ceiling of a semiconductor manufacturing plant. Usually, an OHT system includes a track that constitutes a driving path and a transport vehicle that travels along the track and transports items. In addition, when items need to be kept during transportation between semiconductor manufacturing equipment, a storage system for storing the corresponding items can be set up.
[0004] On the other hand, a branch portion is formed in the travel path of the transport vehicle to guide the vehicle to selectively travel from one path to one of two or more paths. In the corresponding branch portion, the transport vehicle can travel in a straight direction or in a branch direction. As the transport vehicle is required to travel at a higher speed, a technology is required to allow the transport vehicle to travel smoothly while suppressing vibration or shock generated when traveling straight or in a branch direction. Summary of the invention
[0005] Therefore, the embodiments of the present invention provide a transport vehicle, a track, and an article transport system that enable the transport vehicle to travel smoothly in a branching portion of a travel path.
[0006] The problems to be solved by the present invention are not limited to those mentioned above, and those skilled in the art will clearly understand other problems to be solved that are not mentioned from the following description.
[0007] A transport vehicle according to an embodiment of the present invention transports articles in an article transport system of a manufacturing plant, and the transport vehicle comprises: a travel unit that travels along a travel track; and a steering unit that selectively contacts a steering guide track in a branch portion of the travel track. The steering unit comprises: a horizontal steering wheel that contacts a vertical guide portion of the steering guide track; and a vertical steering wheel that contacts a horizontal guide portion of the steering guide track.
[0008] In one embodiment, the steering unit may further include: a moving body that moves in a direction perpendicular to the moving direction of the transport vehicle; a horizontal body that is coupled to the moving body; and a vertical body that is coupled to an upper portion of the horizontal body.
[0009] In one embodiment, the moving body may move in the branch portion in a direction opposite to the moving direction of the transport vehicle.
[0010] In one embodiment, the horizontal steering wheel may be provided as a pair of horizontal steering wheels combined with the horizontal body, and the vertical steering wheel may be provided as a pair of vertical steering wheels combined with the vertical body.
[0011] In one embodiment, the interval between the pair of vertical steering wheels may be greater than the distance between the horizontal guide parts in the intersection of the straight travel guide rail and the branch travel guide rail.
[0012] According to an embodiment of the present invention, a track is used for moving a transport vehicle in an article transport system of a manufacturing plant, and the track includes: a travel track, which provides a path for the transport vehicle to travel; and a steering guide track, which guides the travel direction of the transport vehicle in a branch portion of the travel track. The steering guide track may include: a vertical guide portion, which contacts with a horizontal steering wheel of the transport vehicle to guide the transport vehicle; and a horizontal guide portion, which contacts with a vertical steering wheel of the transport vehicle to guide the transport vehicle.
[0013] In one embodiment, the horizontal guide portion may include: a vertical structure installed facing the vertical guide portion; and a horizontal structure combined to protrude from the vertical structure in a horizontal direction.
[0014] In one embodiment, the turning guide track may include: a straight travel guide track for guiding the transport vehicle in a straight direction; and a branch travel guide track for guiding the transport vehicle in a branch direction.
[0015] In one embodiment, the branch travel guide rail may be formed from the opposite side of the branch direction through an intersection with the straight travel guide rail toward the branch direction.
[0016] In one embodiment, in the intersection portion, the horizontal guide portions may be arranged such that a distance between them is smaller than a distance between a pair of vertical steering wheels of the transport vehicle.
[0017] The article transport system of a manufacturing plant according to an embodiment of the present invention includes: a transport vehicle for transporting articles; and a track for moving the transport vehicle. The track includes: a travel track for providing a path for the transport vehicle to travel; and a steering guide track for guiding the travel direction of the transport vehicle in a branch portion of the travel track. The steering guide track may include: a vertical guide portion for contacting with a horizontal steering wheel of the transport vehicle to guide the transport vehicle; and a horizontal guide portion for contacting with a vertical steering wheel of the transport vehicle to guide the transport vehicle.
[0018] According to an embodiment of the present invention, when branching, the horizontal steering wheels of the transport vehicle contact the vertical guide portion of the steering guide rail and the vertical steering wheels of the transport vehicle contact the horizontal guide portion of the steering guide rail, so that the transport vehicle can travel more smoothly in the branch portion.
[0019] The effects of the present invention are not limited to those mentioned above, and those skilled in the art will clearly understand other effects not mentioned from the following description. BRIEF DESCRIPTION OF THE DRAWINGS
[0020] Figure 1 An example of an article transport system in a manufacturing plant is shown.
[0021] Figure 2 as well as Figure 3 A schematic structure of a transport vehicle according to an embodiment of the present invention is shown.
[0022] Figure 4 as well as Figure 5 An example of a transport vehicle traveling in a branch portion in the article transport system according to the embodiment of the present invention is shown.
[0023] Figure 6 Examples of rails and transport vehicles in the article transport system according to the embodiment of the present invention are shown.
[0024] Figure 7 An example of a turning guide track according to an embodiment of the present invention is shown.
[0025] Figure 8 An example of a steering portion of a transport vehicle according to an embodiment of the present invention is shown.
[0026] Fig. 9 A branching portion of a track according to an embodiment of the invention is shown. DETAILED DESCRIPTION
[0027] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings so that a person having ordinary knowledge in the technical field to which the present invention belongs can easily implement the present invention. The present invention can be implemented in various different ways and is not limited to the embodiments described herein.
[0028] In order to clearly describe the present invention, parts not related to the description are omitted, and the same or similar components are denoted by the same reference numerals throughout the entire specification.
[0029] In addition, among the multiple embodiments, the same reference numerals are used for components having the same structure and only a representative embodiment is described, and in the remaining embodiments, only the structure different from the representative embodiment is described.
[0030] Throughout the specification, when it is stated that a part is "connected (or coupled)" to another part, it includes not only the case of "direct connection (or coupling)" but also the case of "indirect connection (or coupling)" with other components placed in between. In addition, when it is stated that a part "includes" a certain constituent element, unless otherwise stated, it means that other constituent elements may be included rather than excluded.
[0031] Unless otherwise defined, all terms used herein, including technical or scientific terms, have the same meaning as those generally understood by a person having ordinary knowledge in the technical field to which the present invention belongs. Terms such as terms defined in commonly used dictionaries should be interpreted as having the same meaning as that in the context of the relevant technology, and will not be ideally or excessively interpreted as formal meanings unless explicitly defined in this application.
[0032] Figure 1 An example of an article transport system within a manufacturing plant is shown. It may be that a semiconductor or display manufacturing line is composed of one or more clean rooms, and a manufacturing device 1 for performing a manufacturing process is provided in each clean room. Generally, a processed substrate (e.g., a wafer) can be finally completed by repeatedly performing multiple manufacturing processes on the substrate, and if the manufacturing process is completed in a specific semiconductor manufacturing device 1, the substrate is transported to the equipment for the next manufacturing process. Here, the substrate can be transported in a state of being stored in a container that can accommodate multiple substrates (e.g., front opening unified pod, FOUP; front opening wafer transport box). The container containing the substrate can be transported by a transport vehicle (e.g., overhead hoist transport, OHT) 20.
[0033] The vehicle 20 travels on a rail 10 installed on the ceiling and interacts with an upstream server (vehicle control device) that instructs the transfer operation command by wireless communication. The vehicle control device receives a command related to the transfer based on the operation process from the integrated control system. In order to enable the vehicle 20 to complete the transfer operation in the shortest time according to the command of the integrated control system, it searches for the shortest path from the departure point to the destination, selects a transport vehicle 20 located at the best position suitable for performing the transfer operation, and instructs the transfer command. According to the transfer command of the vehicle control device, the transport vehicle 20 moves the logistics from any port indicated by the vehicle control device to the destination port.
[0034] Reference Figure 1 In a semiconductor or display manufacturing line, a manufacturing device 1 for performing a process may be provided. A track 10 forming a transport path (e.g., a ceiling track) for transporting articles between the manufacturing devices 1 and a plurality of transport vehicles 20 running on the track 10 and transporting articles to the manufacturing devices 1 may be provided. At this time, the article transport vehicle 20 may receive a driving power supply through a power supply unit (e.g., a power supply cable) formed along the track 10.
[0035] When the transport vehicle 20 transports articles between the manufacturing equipment 1, the articles can be directly transported from a specific manufacturing equipment to other manufacturing equipment, or the articles can be stored in a storage device and then transported to other manufacturing equipment. A storage device (e.g., an article storage unit 30) can be provided on one side of the track 10. The storage device can include a shelf-shaped storage (stocker) that can be injected with inert gas to maintain a clean environment in the container, a side rail buffer that is provided adjacent to the side of the track 10 and stores the articles, or an under-track buffer that is provided in the lower area of the track 10 and stores the articles, or a maintenance lift for maintaining and repairing the transport vehicle.
[0036] Figure 2 as well as Figure 3 A schematic structure of a transport vehicle 20 according to an embodiment of the present invention is shown. Figure 2 The transport vehicle 20 is shown as viewed from the direction of the travel path. Figure 3 The transport vehicle 20 is shown as viewed from the side of the travel path.
[0037] Reference Figure 2 as well as Figure 3 The transport vehicle 20 includes a travel unit 210 that travels along the travel track 110, a steering unit 220 that selectively contacts the steering guide track in a branch portion of the travel track 110, and a holding unit 230 that holds the transported article.
[0038] The travel unit 210 includes a driving body 211 installed as a device for the transport vehicle 20 to travel, a travel wheel 212 that rotates in contact with the travel rail 110, and a travel guide wheel 213 that rotates in contact with the side of the travel rail 110. The transport vehicle 20 may travel along the travel rail 110 by the rotation of the travel wheel 212, and the travel guide wheel 213 may prevent the transport vehicle 20 from escaping from the travel rail 110.
[0039] The steering unit 220 is a device for guiding the transport vehicle 20 to selectively travel in the branch part. The detailed structure of the steering unit 220 according to the embodiment of the present invention is described in detail below. The holding unit 230 can hold the transport object and load or unload the object on each device 1 through lifting and lowering drive.
[0040] Figure 4 as well as Figure 5 An example of a transport vehicle traveling in a branch portion in the article transport system according to the embodiment of the present invention is shown. Figure 4 The transport vehicle 20 is shown traveling in the branching direction in the branching portion. Figure 5 The transport vehicle 20 is shown traveling in the straight direction at the branching portion.
[0041] like Figure 4 as well as Figure 5 As shown, the branch turning guide track of the turning guide track 120 is formed from the opposite direction of the branch direction through the intersection point with the straight branch guide track to the branch direction. Figure 4 As shown in FIG. 1 , when the transport vehicle 20 moves in a branching direction (eg, left direction), the steering unit 220 of the transport vehicle 20 moves in a direction opposite to the branching direction (eg, right direction). Figure 5 As shown in FIG. 2 , when the transport vehicle 20 travels in the straight direction, the steering unit 220 of the transport vehicle 20 moves in the branch direction (eg, left direction). Figure 4 as well as Figure 5 The turning guide rail 120 shown in the figure allows the turning unit 220 of the transport vehicle 20 to travel along the turning guide rail 120 , thereby reducing the shock and vibration generated when the transport vehicle 20 travels in the branching direction.
[0042] In addition, if Figure 4 as well as Figure 5As shown, when the transport vehicle 20 travels in the branching direction, the one side running wheel 212 of the transport vehicle 20 contacts the travel rail 110, but the opposite side running wheel 212 does not contact the travel rail 110 and becomes a floating state. According to an embodiment of the present invention, instead of the opposite side running wheel 212, the vertical steering wheel 222 of the steering unit 220 contacts the horizontal guide portion 122 of the steering guide rail 120 to travel. That is, when the transport vehicle 20 travels in the branching direction, the one side running wheel 212 contacts the travel rail 110 to travel, and on the opposite side, the vertical steering wheel 222 contacts the horizontal guide portion 122 of the steering guide rail 120 to travel, thereby preventing the transport vehicle 20 from tilting and buffering the impact and vibration that may be generated in the floating state.
[0043] Figure 6 An example of a rail 10 and a transport vehicle 20 in the article transport system according to the embodiment of the present invention is shown. Figure 6 Shown as Figure 5 In this case, the transport vehicle 20 travels in the straight direction.
[0044] The article conveying system of the manufacturing plant according to the embodiment of the present invention includes a conveying vehicle 20 for conveying articles and a track 10 for moving the conveying vehicle 20. In the embodiment of the present invention, the conveying vehicle 20 includes a traveling unit 210 traveling along the traveling track 110 and a steering unit 220 selectively contacting the turning guide track 120 in a branch portion of the traveling track 110. The steering unit 220 includes a horizontal steering wheel 221 contacting the vertical guide portion 121 of the turning guide track 120 and a vertical steering wheel 222 contacting the horizontal guide portion 122 of the turning guide track 120.
[0045] According to an embodiment of the present invention, the track 10 includes a travel track 110 that provides a path for the transport vehicle 20 to travel, and a turning guide track 120 that guides the travel direction of the transport vehicle 20 in a branch portion branched from the travel track 110. The turning guide track 120 includes a vertical guide portion 121 that contacts with a horizontal turning wheel 221 of the transport vehicle 20 to guide the transport vehicle 20, and a horizontal guide portion 122 that contacts with a vertical turning wheel 222 of the transport vehicle 20 to guide the transport vehicle.
[0046] In the embodiment of the present invention, the steering unit 220 further includes a moving body 223 that moves in a direction perpendicular to the moving direction of the transport vehicle 20, a horizontal body 224 coupled to the moving body 223, and a vertical body 225 coupled to the upper side of the horizontal body 224. Figure 6As shown, the moving body 223 can move in the turning part 220 along the guide rail in a direction perpendicular to the driving direction of the transport vehicle 20 (left and right direction). A horizontal body 224 can be installed above the moving body 223, and a vertical body 225 can be installed above the horizontal body 224.
[0047] In the embodiment of the present invention, the moving body 223 can move in the branch portion in a direction opposite to the moving direction of the transport vehicle 20. Figure 4 as well as Figure 5 As shown, when the transport vehicle 20 moves in the branch direction (for example, the left direction), the moving body 223 moves in the direction opposite to the branch direction (for example, the right direction), and when the transport vehicle 20 moves in the straight direction, the moving body 223 moves in the branch direction (for example, the left direction). Figure 4 as well as Figure 5 The turning guide rail 120 shown in the figure allows the turning unit 220 of the transport vehicle 20 to travel along the turning guide rail 120 , thereby reducing the shock and vibration generated when the transport vehicle 20 travels in the branching direction.
[0048] In an embodiment of the present invention, the horizontal steering wheel 221 may be provided as a pair of horizontal steering wheels combined with the horizontal body 224, and the vertical steering wheel 222 may be provided as a pair of vertical steering wheels combined with the vertical body 225. That is, the horizontal steering wheel 221 and the vertical steering wheel 222 may each be configured as a pair of wheels arranged at a certain interval in the front-rear direction. Figure 8 The horizontal steering wheel 221 may include a front horizontal steering wheel 221A and a rear horizontal steering wheel 221B combined with the horizontal body 224. The vertical steering wheel 222 may include a front vertical steering wheel 222A and a rear vertical steering wheel 222B.
[0049] The distance d0 between a pair of vertical steering wheels can be set to be larger than the distances d1 and d2 between the horizontal guides in the intersection of the straight travel guide track and the branch travel guide track. That is, the distance d0 between the front vertical steering wheel 222A and the rear vertical steering wheel 222B is configured to be larger than the area separated by the horizontal guide 122 in the intersection without the horizontal guide 122, so that at least one of the front vertical steering wheel 222A and the rear vertical steering wheel 222B is always in contact with the horizontal guide 122 of the steering guide track 120. Therefore, it is possible to prevent the vertical steering wheel 222 from being in a floating state, and reduce the impact and vibration generated in the floating state.
[0050] On the other hand, according to an embodiment of the present invention, the horizontal guide portion 122 of the turning guide rail 120 may include a vertical structure 122A installed opposite to the vertical guide portion 121 and a horizontal structure 122B combined to protrude from the vertical structure 122A in the horizontal direction.
[0051] In an embodiment of the present invention, the turning guide rail 120 may include a straight travel guide rail for guiding the transport vehicle 20 in a straight direction and a branch travel guide rail for guiding the transport vehicle 20 in a branch direction. Figure 6 The straight travel guide track may include a straight travel vertical guide portion 121 and a straight travel horizontal guide portion 122 , and the branch travel guide track may include a branch travel vertical guide portion 123 and a straight travel horizontal guide portion 124 .
[0052] In an embodiment of the present invention, the branch travel guide track may be formed from the opposite side of the branch direction through the intersection with the straight travel guide track toward the branch direction. Figure 7 As shown, the branch travel guide rails 123 and 124 can be formed from the opposite direction of the branch direction through the intersection with the straight travel guide rails 121 and 122 to the branch direction.
[0053] In addition, if Fig. 9 As shown, in order to realize the N-shaped branching part, the branching travel guide rails 123 and 124 can be formed from the opposite direction of the branching direction through the intersection with the straight travel guide rails 121 and 122 to the branching direction, and then extend to the outer side of the curved path of the transport vehicle 20 at the confluence. In this case, at least one of the front vertical steering wheel 222A and the rear vertical steering wheel 222B is always in contact with the horizontal guide part 122 of the steering guide rail 120 in both the branching part and the confluence. Therefore, in the branching part and the confluence, it is possible to prevent the vertical steering wheel 222 from being in a floating state, and reduce the impact and vibration generated in the floating state.
[0054] As described above, in the intersection, the distance between the horizontal guides 122 is set smaller than the distance between the pair of vertical steering wheels of the transport vehicle 20. That is, in the intersection, the distance between the horizontal guides 122 is configured to be smaller than the distance between the front vertical steering wheel 222A and the rear vertical steering wheel 222B, so that at least one of the front vertical steering wheel 222A and the rear vertical steering wheel 222B is always in contact with the horizontal guide 122 of the steering guide rail 120. Thus, it is possible to prevent the vertical steering wheel 222 from being in a floating state, and to reduce the shock and vibration generated in the floating state.
[0055] In addition, according to an embodiment of the present invention, the vertical steering wheel 222 is not only formed at the front / rear, but can also be formed on both sides with the vertical body 225 as the center. In this case, a horizontal structure 122B that can contact the vertical steering wheel 222 can also be formed in the vertical guide portion 121 of the steering guide rail 120. The vertical steering wheels 222 are formed on both sides with the vertical body 225 as the center, and a horizontal structure is formed in which the vertical steering wheel 222 can contact both the vertical guide portion 121 and the horizontal guide portion 122, so that the transport vehicle 20 can travel more stably in the branch portion.
[0056] This embodiment and the drawings attached to this specification only clearly indicate a part of the technical concept included in the present invention. It is obvious that modifications and specific embodiments that can be easily derived by those skilled in the art within the scope of the technical concept included in the specification and drawings of the present invention are all included in the scope of rights of the present invention.
[0057] Therefore, the concept of the present invention should not be limited to the illustrated embodiments, but rather to the appended claims. All concepts that are equivalent to or equivalently modified to the claims belong to the scope of the concept of the present invention.
Claims
1. A transport vehicle for transporting articles in an article transport system of a manufacturing plant. It is characterized in that The transport vehicle includes: A travel unit, which travels along the travel track; and a steering unit, selectively contacting the steering guide rail in a branch portion of the travel rail branch, The steering unit comprises: a horizontal steering wheel in contact with a vertical guide portion of the steering guide track; a vertical steering wheel in contact with a horizontal guide portion of the steering guide track; and The moving body moves in a direction perpendicular to the moving direction of the transport vehicle. When the transport vehicle passes through the branch portion, the travel unit is replaced by the travel unit being in a floating state without contact with the travel rail, and the vertical steering wheel contacts the horizontal guide portion. The steering guide track comprises: A straight travel guide track guides the transport vehicle in a straight travel direction; and The branch travel guide track guides the transport vehicle to the branch direction. The branch travel guide rail is formed from the opposite side of the branch direction through the intersection with the straight travel guide rail toward the branch direction. When the transport vehicle moves in the branching direction, the moving body moves in the direction opposite to the branching direction in the branching portion.
2. The transport vehicle according to claim 1, It is characterized in that The steering unit also includes: a horizontal body, combined with the moving body; and The vertical body is combined with the upper part of the horizontal body.
3. The transport vehicle according to claim 2, It is characterized in that The horizontal steering wheels are provided as a pair of horizontal steering wheels combined with the horizontal body, The vertical steering wheels are provided as a pair of vertical steering wheels combined with the vertical body.
4. The transport vehicle according to claim 3, It is characterized in that The interval between the pair of vertical steering wheels is larger than the distance between the horizontal guide parts in the intersection of the straight travel guide rail and the branch travel guide rail.
5. A track used for moving vehicles in a goods handling system in a manufacturing plant. It is characterized in that The track includes: A travel track providing a path for a travel unit of the transport vehicle to travel; and The turning guide track includes: a straight travel guide track for guiding the travel direction of the transport vehicle in the straight direction at a branching portion of the travel track; and a branch travel guide track for guiding the transport vehicle in the branching direction. The steering guide track comprises: a vertical guide portion contacting with a horizontal steering wheel of the transport vehicle to guide the transport vehicle; and a horizontal guide part contacting with the vertical steering wheel of the transport vehicle to guide the transport vehicle, When the transport vehicle passes through the branch portion, the travel unit is replaced by the horizontal guide portion contacting the vertical steering wheel instead of being in a floating state without contacting the travel rail. The branch travel guide rail is formed from the opposite side of the branch direction through the intersection with the straight travel guide rail toward the branch direction. The transport vehicle includes: A travel unit, which travels along the travel track; and a steering unit, selectively contacting the steering guide rail in a branch portion of the travel rail branch, The steering unit comprises: a horizontal steering wheel in contact with a vertical guide portion of the steering guide track; a vertical steering wheel in contact with a horizontal guide portion of the steering guide track; and The moving body moves in a direction perpendicular to the moving direction of the transport vehicle. When the transport vehicle moves in the branching direction, the moving body moves in the direction opposite to the branching direction in the branching portion.
6. The track according to claim 5, It is characterized in that The horizontal guide portion comprises: a vertical structure installed facing the vertical guide portion; and The horizontal structure is combined to protrude from the vertical structure in a horizontal direction.
7. The track according to claim 5, It is characterized in that In the intersection portion, the horizontal guide portions are spaced apart by a distance smaller than a distance between a pair of vertical steering wheels of the transport vehicle.
8. An article transport system in a manufacturing plant, It is characterized in that The article transport system comprises: Moving vehicles and moving goods; and Tracks, used to transport vehicles, The track includes: A travel track providing a path for a travel unit of the transport vehicle to travel; and The turning guide track includes: a straight travel guide track for guiding the travel direction of the transport vehicle in the straight direction at a branching portion of the travel track; and a branch travel guide track for guiding the transport vehicle in the branching direction. The steering guide track comprises: a vertical guide portion contacting with a horizontal steering wheel of the transport vehicle to guide the transport vehicle; and a horizontal guide part contacting with the vertical steering wheel of the transport vehicle to guide the transport vehicle, When the transport vehicle passes through the branch portion, the travel unit is replaced by the horizontal guide portion contacting the vertical steering wheel instead of being in a floating state without contacting the travel rail. The branch travel guide rail is formed from the opposite side of the branch direction through the intersection with the straight travel guide rail toward the branch direction. The transport vehicle includes: A travel unit, which travels along the travel track; and a steering unit, selectively contacting the steering guide rail in a branch portion of the travel rail branch, The steering unit comprises: a horizontal steering wheel in contact with a vertical guide portion of the steering guide track; a vertical steering wheel in contact with a horizontal guide portion of the steering guide track; and The moving body moves in a direction perpendicular to the moving direction of the transport vehicle. When the transport vehicle moves in the branching direction, the moving body moves in the direction opposite to the branching direction in the branching portion.
9. The article transport system according to claim 8, It is characterized in that The steering unit also includes: a horizontal body, combined with the moving body; and The vertical body is combined with the upper part of the horizontal body.
10. The article transport system according to claim 9, It is characterized in that The horizontal steering wheels are provided as a pair of horizontal steering wheels combined with the horizontal body, The vertical steering wheels are provided as a pair of vertical steering wheels combined with the vertical body.
11. The article transport system according to claim 10, It is characterized in that The interval between the pair of vertical steering wheels is larger than the distance between the horizontal guide parts in the intersection of the straight travel guide rail and the branch travel guide rail.
12. The article transport system according to claim 8, It is characterized in that The horizontal guide portion comprises: a vertical structure installed facing the vertical guide portion; and The horizontal structure is combined to protrude from the vertical structure in a horizontal direction.
13. The article transport system according to claim 8, It is characterized in that In the intersection portion, the horizontal guide portions are spaced apart by a distance smaller than a distance between a pair of vertical steering wheels of the transport vehicle.