ARTICLE TRANSPORT DEVICE

This Nonprovisional application claims priority under 35 U.S.C. § 119 on Patent Application No. 2023-094982 filed in Japan on Jun. 8, 2023, the entire contents of which are hereby incorporated by reference.

TECHNICAL FIELD

The present invention relates to an article transport device.

BACKGROUND ART

An article transport device that travels along a guide rail so as to transport an article is conventionally known. For example, Patent Literatures 1 and 2 each disclose a traveling vehicle that an article transport device has. The traveling vehicle has a pair of guide rollers between which a rail on which a wheel of the traveling vehicle rolls is sandwiched from both sides. Driving of a driving wheel of the traveling vehicle causes each of the pair of guide rollers to roll on a side surface of the rail. This allows the article transport device to travel along the rail.

CITATION LIST
Patent Literature

[Patent Literature 1]

Japanese Patent No. 2572993

[Patent Literature 2]

Japanese Patent No. 3702738

SUMMARY OF INVENTION
Technical Problem

Note that each of a pair of guide rollers is worn as a result of traveling of a traveling vehicle. Wear of the guide rollers increases a tilt of the traveling vehicle with respect to a rail. Thus, it is considered that wear of the guide rollers causes, for example, a decrease in straight traveling performance of an article transport device.

An object of an aspect of the present invention is to sense that a first guide roller of a first guide roller pair has been worn and/or that a second guide roller of a second guide roller pair has been worn.

Solution to Problem

In order to attain the object, an article transport device in accordance with an aspect of the present invention includes a traveling vehicle, the traveling vehicle having: a first wheel; a second wheel that is disposed so as to be spaced apart from the first wheel in a traveling direction, which is a direction along a guide rail; a first guide roller pair that has a pair of first guide rollers between which the guide rail is sandwiched in a direction intersecting the traveling direction; a second guide roller pair that has a pair of second guide rollers between which the guide rail is sandwiched in the direction intersecting the traveling direction and that is disposed so as to be spaced apart from the first guide roller pair in the traveling direction; a frame in which the traveling direction is a longitudinal direction and to which the first guide rollers and the second guide rollers are attached; a first sensor which detects a horizontal distance between the frame and the guide rail; and a second sensor which is disposed so as to be spaced apart from the first sensor in the traveling direction and which detects the horizontal distance between the frame and the guide rail, the first sensor and the second sensor each being attached to the frame, the first guide roller pair being located closer to the first wheel than the second guide roller pair and the second sensor in the traveling direction, the first sensor being located closer to the first wheel than the second guide roller pair and the second sensor in the traveling direction, a distance between the first sensor and the first guide roller pair in the traveling direction being shorter than a distance between the first sensor and the first wheel in the traveling direction, and a distance between the second sensor and the second guide roller pair in the traveling direction being shorter than a distance between the second sensor and the second wheel in the traveling direction.

Advantageous Effects of Invention

An aspect of the present invention makes it possible to sense that a first guide roller of a first guide roller pair has been worn and/or that a second guide roller of a second guide roller pair has been worn.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a view schematically illustrating an example of an article transport facility in accordance with Embodiment 1 of the present invention.

FIG. 2 is a perspective view of a stacker crane illustrated in FIG. 1.

FIG. 3 is a perspective view of a traveling vehicle of the stacker crane illustrated in FIG. 2.

FIG. 4 is a plan view of the traveling vehicle of the stacker crane illustrated in FIG. 2, as viewed from above.

FIG. 5 is a plan view of a raising and lowering platform of the stacker crane illustrated in FIG. 2, as viewed from above.

FIG. 6 is a cross-sectional view of the raising and lowering platform of the stacker crane illustrated in FIG. 2, as viewed from the right side.

FIG. 7 is a view schematically describing a bar code reader and a bar code provided on a side surface of a traveling rail.

FIG. 8 is a block diagram illustrating an electrical of the configuration stacker crane illustrated in FIG. 2.

FIG. 9 is a view schematically describing tilts of a traveling vehicle, a raising and lowering platform, and a fork section with respect to a traveling guide rail when a stacker crane is stopped.

FIG. 10 is a plan view of a stacker crane of an article transport facility in accordance with Embodiment 2 of the present invention, as viewed from above.

FIG. 11 provides (i) a cross-sectional view taken at a central position illustrated in FIG. 10 and (ii) a cross-sectional view taken along line A-A illustrated in FIG. 10.

DESCRIPTION OF EMBODIMENTS
Embodiment 1

The following will describe an embodiment of the present invention in detail with reference to FIGS. 1 to 9.

[Article Transport Facility]

An overview of an article transport facility 100 will be described with reference to FIG. 1. FIG. 1 is a view schematically illustrating an example of the article transport facility 100. Further, for convenience of description, an up-down direction, a front-rear direction, and a right-left direction are defined as indicated by arrows in FIG. 1, etc. Note that, in the present embodiment, the up-down direction is a direction orthogonal to the front-rear direction and the right-left direction, and the front-rear direction is a direction orthogonal to the right-left direction.

The article transport facility 100 illustrated in FIG. 1 includes a stacker crane 1, load shelves 2, a traveling guide rail 3, and a traveling rail 4. The load shelves 2 are each a shelf on which an article can be placed. The load shelves 2 are each provided with a plurality of stages in the up-down direction, and a space for placing an article is partitioned in the right-left direction of each of the stages. The traveling guide rail 3 and the traveling rail 4 that constitute a traveling path of the stacker crane 1 are installed on a floor between a front load shelf 2 and a rear load shelf 2, and the stacker crane 1 is capable of traveling in a space between the front load shelf 2 and the rear load shelf 2. The traveling guide rail 3 is an example of a guide rail. The traveling rail 4 is installed in parallel with the traveling guide rail 3. A longitudinal direction of each of the traveling guide rail 3 and the traveling rail 4 is the right-left direction.

The stacker crane 1 device for transporting an article. The stacker crane 1 is an example of an article transport device. A height of the stacker crane 1 in the up-down direction is about 2 m to 18 m. The stacker crane 1 travels along the traveling guide rail 3. In the present embodiment, a traveling direction D1 of the stacker crane 1 is the right-left direction. In the article transport facility 100, a plurality of stacker cranes 1 travel on a single traveling guide rail 3 and a single traveling rail 4. Note that the article transport facility 100 may be configured such that one stacker crane 1 travels on the traveling guide rail 3 and the traveling rail 4.

In the following description, the stacker crane 1 illustrated in a left-hand part of FIG. 1 is referred to as a stacker crane 1A, and the stacker crane 1 illustrated in a right-hand part of FIG. 1 is referred to as a stacker crane 1B.

In a case where the stacker cranes 1A and 1B are in a standby state in which no article is transported, the stacker cranes 1A and 1B are kept on standby at home positions HP1 and HP2, respectively. The home position HP1 of the stacker crane 1A is provided on the left side of the traveling guide rail 3, and the home position HP2 of the stacker crane 1B is provided on the right side of the traveling guide rail 3. A loading and unloading port EP1 through which an article is transferred to or from the stacker crane 1A is provided on the right side of the home position HP1. A loading and unloading port EP2 through which an article is transferred to or from the stacker crane 1B is provided on the left side of the home position HP2. Note that the home position HP1 and the loading and unloading port EP1 may be located at an identical position and that the home position HP2 and the loading and unloading port EP2 may be located at an identical position. A transport position CP1 is a position at which the stacker crane 1A can load or unload an article on or from the front load shelf 2 or the rear load shelf 2. A transport position CP2 is a position at which the stacker crane 1B can load or unload an article on or from the front load shelf 2 or the rear load shelf 2. The transport positions CP1 and CP2 vary in accordance with a position of the front or rear load shelf 2 on which an article to be loaded or unloaded is placed. The transport position CP1 of the stacker crane 1A is a position on the traveling guide rail 3 which position is more rightward than the loading and unloading port EP1. The transport position CP2 of the stacker crane 1B is a position on the traveling guide rail 3 which position is more leftward than the loading and unloading port EP2.

The stacker crane 1A moves to the home position HP1, the loading and unloading port EP1, or the transport position CP1 in accordance with a transport command signal. The stacker crane 1B moves to the home position HP2, the loading and unloading port EP2, or the transport position CP2 on the basis of the transport command signal. For example, in a case where the stacker crane 1A receives the transport command signal for loading an article in the fourth row from the left on the front load shelf 2, the stacker crane 1A receives the article from a loading conveyor at the loading and unloading port EP2 and then moves to the transport position CP1 illustrated in FIG. 1. Upon completion of loading of the article in the front load shelf 2 at the transport position CP1 illustrated in FIG. 1, the stacker crane 1A moves to the home position HP1, the loading and unloading port EP1, or the transport position CP1 in accordance with a subsequent transport command signal. In contrast, in a case where the stacker crane 1A receives the transport command signal for picking an article placed in the fourth row from the left on the front load shelf 2, the stacker crane 1A moves to the transport position CP1 illustrated in FIG. 1. Upon completion of picking of the article from the load shelf 2A at the transport position CP1 illustrated in FIG. 1, the stacker crane 1A moves to the loading and unloading port EP1 and transfers the article to an unloading conveyor at the loading and unloading port EP1. The stacker crane 1A moves to the home position HP1, the loading and unloading port EP1, or the transport position CP1 in accordance with a subsequent transport command signal.

The loading and unloading ports EP1 and EP2 are each located on an outside of the load shelves 2 in the traveling direction. Note, however, that the present invention is not limited to such a configuration. The loading and unloading ports EP1 and EP2 each may be located at a position that overlaps a corresponding one of the load shelves 2 in the traveling direction. That is, the loading and unloading ports EP1 and EP2 each may be provided to a corresponding one of the front and rear load shelves 2. In this case, openings through each of which an article can be transferred are formed in the load shelves 2 that are provided with the loading and unloading ports EP1 and EP2. For example, the stacker crane 1A stops in front of a row of the load shelf 2 that is provided with the loading and unloading port EP1. Further, the loading and unloading ports EP1 and EP2 are loading and unloading ports that are different from each other. Note, however, that the present invention is not limited to such a configuration. The loading and unloading port EP2 may be a loading and unloading port that is identical to the loading and unloading port EP1.

[Stacker Crane]

Next, a detailed configuration of the stacker crane 1A will be described with reference to FIGS. 2 to 7. FIG. 2 is a perspective view illustrating the stacker crane 1A illustrated in FIG. 1. As illustrated in FIG. 2, the stacker crane 1A includes a mast 10, a traveling vehicle 20, a raising and lowering platform 30, a control box 40, and a driver box 45.

[Mast]

The mast 10 is a columnar member that extends in the up-down direction. The stacker crane 1A is provided with a pair of masts 10. Note that, in the following description, the mast 10 illustrated in the left-hand part of the drawing (the mast 10 on the home position HP1 side) is referred to as a first mast 10A, and the mast 10 illustrated in the right-hand part of the drawing (the mast 10 on the transport position CP1 side) is referred to as a second mast 10B.

The first mast 10A and the second mast 10B are spaced apart from each other in the right-left direction. The raising and lowering platform 30 (described later) is provided between the first mast 10A and the second mast 10B. The first mast 10A and the second mast 10B are provided with respective raising and lowering guide rails 11. The raising and lowering guide rails 11 guide the raising and lowering platform 30 in the up-down direction.

To upper parts of the masts 10, an upper frame 12 is provided. The upper frame 12 is provided so as to connect an upper end portion of the first mast 10A and an upper end portion of the second mast 10B. The upper frame 12 is engaged with an upper rail (not illustrated) that is provided so as to be parallel to the traveling guide rail 3. Further, the upper frame 12 is provided with a guide roller(s), and the upper parts of the masts 10 are guided along the upper rail by the guide roller(s) of the upper frame 12. That is, the upper end portions of the masts 10 are guided in the traveling direction D1 by the upper rail. Note that the stacker crane 1A may be configured not to have the upper frame 12.

Raising and lowering motors 13, which are driving sections for raising and lowering the raising and lowering platform 30 with respect to the masts 10, are provided to lower parts of the respective pair of masts 10. The raising and lowering motors 13 are provided on a rear side of the masts 10, that is, on the traveling rail 4 side with respect to the masts 10.

The raising and lowering motors 13 drive driving drums (not illustrated) that are provided to the lower parts of the respective masts 10. In a case where the raising and lowering motors 13 rotate forward or backward, raising and lowering belts (not illustrated) wound on the respective driving drums advance or retract with respect to the driving drums. Pulleys for locking the raising and lowering belts are provided to the upper parts of the respective pair of masts 10. The raising and lowering platform 30 is fixed to one end of a raising and lowering belt, and a counterweight is fixed to the other end of the raising and lowering belt. Advance or retraction of the raising and lowering belts moves the raising and lowering platform 30 in the up-down direction along the raising and lowering guide rails 11. That is, the raising and lowering platform 30 is raised and lowered with respect to the masts 10 in a raising and lowering direction D2 by driving of the raising and lowering motors 13. Note that the raising and lowering platform 30 may be configured to be raised and lowered with respect to the masts 10 by raising and lowering wires or raising and lowering chains in place of the raising and lowering belts.

[Traveling Vehicle]

Next, a detailed configuration of the traveling vehicle 20 will be described with reference to FIGS. 3 and 4. FIG. 3 is a perspective view of the traveling vehicle 20 of the stacker crane 1A illustrated in FIG. 2. FIG. 4 is a plan view of the traveling vehicle 20 of the stacker crane 1A illustrated in FIG. 2, as viewed from above. As illustrated in FIGS. 3 and 4, the traveling vehicle 20 has a vehicle frame 21. The vehicle frame 21 is constituted by a first side frame 211, a second side frame 212, a first connection frame 213, and a second connection frame 214. In the present embodiment, the first side frame 211, the second side frame 212, the first connection frame 213, and the second connection frame 214 are integrally formed.

Note that the frames 211 to 214 constituting the vehicle frame 21 are not limited to those integrally formed and may be separate members. In this case, a left end portion of the first connection frame 213 and a left end portion of the second connection frame 214 are fixed to the first connection frame 213 by a bolt or the like. Further, a right end portion of the first connection frame 213 and a right end portion of the second connection frame 214 are fixed to the second connection frame 214 by a bolt or the like. In a case where the frames 211 to 214 are separate members, the stacker crane 1 that has a large size can be delivered in a disassembled state. Thus, the stacker crane 1 can be transported in a compact manner while being delivered.

As illustrated in FIG. 3, the first side frame 211 is a frame that is located in a front part of the traveling vehicle 20, and extends in a direction along the traveling guide rail 3 and the traveling rail 4. That is, the first side frame 211 is a frame in which the right-left direction, which is the traveling direction D1, is the longitudinal direction. The second side frame 212 is a frame that is located in a rear part of the traveling vehicle 20, and extends in the direction along the traveling guide rail 3 and the traveling rail 4. That is, the second side frame 212 is a frame in which the right-left direction is the longitudinal direction. As illustrated in FIG. 4, the second side frame 212 faces the first side frame 211 in the front-rear direction. A length of the second side frame 212 in the right-left direction is shorter than a length of the first side frame 211 in the right-left direction.

As illustrated 3, in FIG. 3, the first connection frame 213 is a frame that connects the first side frame 211 and the second side frame 212, and is located on the left side with respect to the traveling vehicle 20. More specifically, the first connection frame 213 connects a left end portion of the first side frame 211 and a left end portion of the second side frame 212. The first connection frame 213 is a frame in which the front-rear direction is the longitudinal direction. As illustrated in FIG. 4, the first mast 10A is erected on the first connection frame 213.

As illustrated in FIG. 3, the second connection frame 214 is a frame that connects the first side frame 211 and the second side frame 212, and is located on the right side with respect to the traveling vehicle 20. More specifically, the second connection frame 214 connects a right end portion of the first side frame 211 and a right end portion of the second side frame 212. The second connection frame 214 is a frame in which the front-rear direction is the longitudinal direction. The second connection frame 214 faces the first connection frame 213 in the right-left direction. As illustrated in FIG. 4, the second mast 10B is erected on the second connection frame 214.

As illustrated in FIG. 3, the traveling vehicle 20 has a plurality of wheels that travel on the traveling guide rail 3 and the traveling rail 4. More specifically, the traveling vehicle 20 has a first driving wheel 22, a second driving wheel 23, a first driven wheel 24, and a second driven wheel 25. The first driving wheel 22 is an example of a first wheel, and the second driving wheel 23 is an example of a second wheel.

The first driving wheel 22 and the second driving wheel 23 are attached to the first side frame 211 and roll on an upper surface of the traveling guide rail 3. The first driving wheel 22 is disposed so as to be spaced apart from the second driving wheel 23 in the right-left direction. More specifically, the first driving wheel 22 is located on the left end portion side of the first side frame 211 when viewed from a central position CL in the right-left direction of the vehicle frame 21. The second driving wheel 23 is located on the right end portion side of the first side frame 211 when viewed from the central position CL. The first driving wheel 22 is located on the left side of the first connection frame 213 in the right-left direction. The second driving wheel 23 is located on the right side of the second connection frame 214 in the right-left direction.

The first driven wheel 24 and the second driven wheel 25 are attached to the second side frame 212 and roll on an upper surface of the traveling rail 4. The first driven wheel 24 is disposed so as to be spaced apart from the second driven wheel 25 in the right-left direction. More specifically, the first driven wheel 24 is located on the left end portion side of the second side frame 212 when viewed from the central position CL in the right-left direction of the vehicle frame 21. The second driven wheel 25 is located on the right end portion side of the second side frame 212 when viewed from the central position CL. The first driven wheel 24 is located on the right side of the first driving wheel 22 in the right-left direction. The second driven wheel 25 is located on the left side of the second driving wheel 23 in the right-left direction.

The vehicle frame 21 is provided with traveling motors 26 that are driving sections for causing the stacker crane 1A to travel. Note that, in the following description, the traveling motor 26 illustrated in the left-hand part of the drawing (the traveling motor 26 on the home position HP1 side) is referred to as a first traveling motor 26A, and the traveling motor 26 illustrated in the right-hand part of the drawing (the traveling motor 26 on the transport position CP1 side) is referred to as a second traveling motor 26B. The first traveling motor 26A is located on the left end portion side of the first side frame 211 and drives the first driving wheel 22. The second traveling motor 26B is located on the right end portion side of the first side frame 211 and drives the second driving wheel 23.

The traveling vehicle 20 has a first guide roller pair 28 and a second guide roller pair 29. The first guide roller pair 28 and the second guide roller pair 29 are attached to the first side frame 211. The second guide roller pair 29 is disposed so as to be spaced apart from the first guide roller pair 28 in the right-left direction. The first guide roller pair 28 is located on the left side in the right-left direction, and the second guide roller pair 29 is located on the right side in the right-left direction. That is, the first guide roller pair 28 is located closer to the first driving wheel 22 than the second guide roller pair 29 in the right-left direction. Further, the first guide roller pair 28 is located closer to the first driving wheel 22 than a second distance sensor 80B (described later) in the right-left direction. The first guide roller pair 28 and the second guide roller pair 29 are located between the first driving wheel 22 and the second driving wheel 23 in the right-left direction.

In a case where the first guide roller pair 28 and the second guide roller pair 29 are located between the first driving wheel 22 and the second driving wheel 23, the first guide roller pair 28 and the second guide roller pair 29 are provided in an empty space between the first driving wheel 22 and the second driving wheel 23. This makes it possible to provide the first guide roller pair 28 and the second guide roller pair 29 to a frame of the traveling vehicle 20 without any constraint imposed by other members.

As illustrated in FIG. 4, when viewed from the central position CL in the right-left direction of the vehicle frame 21, the first guide roller pair 28 is located on the left side of the first side frame 211 and is located on the right side of the first connection frame 213. The first guide roller pair 28 is constituted by a pair of first guide rollers 281. The traveling guide rail 3 is sandwiched between the pair of first guide rollers 281 in the front-rear direction. More specifically, a front first guide roller 281 comes into contact with a front side surface of the traveling guide rail 3 and rolls on the front side surface of the traveling guide rail 3. A rear first guide roller 281 comes into contact with a rear side surface of the traveling guide rail 3 and rolls on the rear side surface of the traveling guide rail 3.

When viewed from the central position CL in the right-left direction of the vehicle frame 21, the second guide roller pair 29 is located on the right side of the first side frame 211 and is located on the left side of the second connection frame 214. The second guide roller pair 29 is constituted by a pair of second guide rollers 291. The traveling guide rail 3 is sandwiched between the pair of second guide rollers 291 in the front-rear direction. More specifically, a front second guide roller 291 comes into contact with the front side surface of the traveling guide rail 3 and rolls on the front side surface of the traveling guide rail 3. A rear second guide roller 291 comes into contact with the rear side surface of the traveling guide rail 3 and rolls on the rear side surface of the traveling guide rail 3.

The first guide rollers 281 of the first guide roller pair 28 and the second guide rollers 291 of the second guide roller pair 29 are elastic rollers. As an example, the first guide rollers 281 and the second guide rollers 291 are made of urethane. In a case where the first driving wheel 22 and the second driving wheel 23 are driven, the traveling vehicle 20 is guided in a direction along the traveling guide rail 3 by the first guide roller pair 28 and the second guide roller pair 29. Thus, the stacker crane 1A travels in the traveling direction D1.

According to the above configuration, the traveling guide rail 3 on which the first driving wheel 22 and the second driving wheel 23 travel are sandwiched by the first guide roller pair 28 and the second guide roller pair 29. This allows the traveling vehicle to easily travel straight in the traveling direction D1 by the first guide roller pair 28 and the second guide roller pair 29. This makes it possible to improve straight traveling performance of the traveling vehicle.

As illustrated in FIG. 3, a plurality of distance sensors 80 are attached to the first side frame 211 of the traveling vehicle 20. The distance sensors 80 are sensors that detect a horizontal distance between the first side frame 211 and the traveling guide rail 3. More specifically, the distance sensors 80 detect a horizontal distance between a front surface of the first side frame 211 and the rear side surface of the traveling guide rail 3. In the present embodiment, the distance sensors 80 detect a distance in the front-rear direction between the first side frame 211 and the traveling guide rail 3. Examples of the distance sensors 80 include infrared sensors.

In the following description, the distance sensor 80 illustrated in the left-hand part of the drawing (the distance sensor 80 on the home position HP1 side) is referred to as a first distance sensor 80A, and the distance sensor 80 illustrated in the right-hand part of the drawing (the distance sensor 80 on the transport position CP1 side) is referred to as a second distance sensor 80B. The first distance sensor 80A is an example of a first sensor, and the second distance sensor 80B is an example of a second sensor.

As illustrated in FIG. 4, the first distance sensor 80A and the second distance sensor 80B are located between the first driving wheel 22 and the second driving wheel 23 in the right-left direction. More specifically, the first distance sensor 80A and the second distance sensor 80B are located between the first guide roller pair 28 and the second guide roller pair 29 in the right-left direction. In a case where the first distance sensor 80A and the second distance sensor 80B are located between the first driving wheel 22 and the second driving wheel 23, the first distance sensor 80A and the second distance sensor 80B are installed in an empty space between the first driving wheel 22 and the second driving wheel 23. This makes it possible to attach the first distance sensor 80A and the second distance sensor 80B to the frame of the traveling vehicle 20 without any constraint imposed by other members.

Note that the first distance sensor 80A may be located between the first driving wheel 22 and the first guide roller pair 28 in the right-left direction. Further, the second distance sensor 80B may be located between the second driving wheel 23 and the second guide roller pair 29 in the right-left direction.

The first distance sensor 80A is disposed so as to be spaced apart from the second distance sensor 80B in the right-left direction. The first distance sensor 80A is located on the left side in the right-left direction, and the second distance sensor 80B is located on the right side in the right-left direction. That is, the first distance sensor 80A is located closer to the first driving wheel 22 than the second distance sensor 80B in the right-left direction. Further, the first distance sensor 80A is located closer to the first driving wheel 22 than the second guide roller pair 29 in the right-left direction. The first distance sensor 80A and the second distance sensor 80B are attached to the vehicle frame 21 on opposite sides in the right-left direction when viewed from the central position CL in the right-left direction. The first distance sensor 80A is on the left when viewed from the central position CL in the right-left direction of the first side frame 211, and the second distance sensor 80B is on the right when viewed from the central position CL in the right-left direction of the first side frame 211.

The above configuration makes it possible to widen a distance between (a) the first distance sensor 80A that is located on one side from the central position CL in the right-left direction and (b) the second distance sensor 80B that is located on the other side from the central position CL in the right-left direction. This makes it possible to more accurately detect a tilt of a traveling vehicle with respect to a guide rail.

The first distance sensor 80A is attached to a position closer to the first driving wheel 22 than the second distance sensor 80B. The first distance sensor 80A is disposed near the first guide roller pair 28. Specifically, a distance L1 in the right-left direction between the first distance sensor 80A and the first guide roller pair 28 is shorter than a distance L2 in the right-left direction between the first distance sensor 80A and the first driving wheel 22. More specifically, the distance L1 is a distance in the right-left direction between the first distance sensor 80A and a center of a rotation axis of the first guide rollers 281 of the first guide roller pair 28. Further, the distance L2 is a distance in the right-left direction between the first distance sensor 80A and a center of a rotation axis of the first driving wheel 22.

The second distance sensor 80B is disposed near the second guide roller pair 29. Specifically, a distance L3 in the right-left direction between the second distance sensor 80B and the second guide roller pair 29 is shorter than a distance L4 in the right-left direction between the second distance sensor 80B and the second driving wheel 23. More specifically, the distance L3 is a distance in the right-left direction between the second distance sensor 80B and a center of a rotation axis of the rear second guide rollers 291 of the second guide roller pair 29. The distance L4 is a distance in the right-left direction between the second distance sensor 80B and a center of a rotation axis of the second driving wheel 23.

As illustrated in FIGS. 3 and 4, a bar code reader 81 is attached to the second side frame 212 of the traveling vehicle 20. The bar code reader 81 is a device that reads a bar code 83 provided on a front side surface of the traveling rail 4. The bar code reader 81 is disposed between the traveling guide rail 3 and the traveling rail 4 in top view. That is, the bar code reader 81 is attached to the traveling vehicle 20 so as to be located between the traveling guide rail 3 and the traveling rail 4 in the front-rear direction. The bar code reader 81 faces the front side surface of the traveling rail 4.

The bar code reader 81 and the bar code 83 are described here with reference to FIG. 7. FIG. 7 is a view schematically describing the bar code reader 81 and the bar code 83 provided on the side surface of the traveling rail 4. As illustrated in FIG. 7, the bar code 83 is provided on the side surface of the traveling rail 4. More specifically, the bar code 83 is provided on the front side surface of the traveling rail 4. The bar code 83 includes position information that is information pertaining to a position in the longitudinal direction of the traveling rail 4. The position information included in the bar code 83 is information corresponding to a position of the stacker crane 1A in the traveling direction. The stacker crane 1A moves to the home position HP1 or the transport position CP1 on the basis of the position information read from the bar code 83 of the traveling rail 4.

As illustrated in FIG. 4, an emergency stop sensor 82 is attached to the first side frame 211. The emergency stop sensor 82 is a sensor for stopping traveling of the stacker crane 1A in a case where the stacker crane 1A travels beyond the home position HP1 or the transport position CP1 at which the stacker crane 1A is scheduled to stop.

A cable 90 is a cable that supplies motive power to the stacker crane 1A. The cable 90 makes it possible to supply electric power to each drive section of the stacker crane 1A. The cable 90 is held by a Cableveyor (registered trademark) and is driven by traveling of the stacker crane 1A. In a direction orthogonal to the traveling direction D1 in top view, the cable 90 is connected to the traveling vehicle 20 from a rear-side region that is among two regions obtained by partitioning with the traveling rail 4 serving as a center and that is opposite from a front-side region in which the traveling guide rail 3 is located. That is, in the front-rear direction, the cable 90 is connected to the traveling vehicle 20 from behind the traveling rail 4 with the traveling rail 4 at the center between the front-side and rear-side regions.

[Raising and Lowering Platform]

A detailed configuration of the raising and lowering platform 30 will be described with reference to FIGS. 5 and 6. FIG. 5 is a plan view of the raising and lowering platform 30 of the stacker crane 1A illustrated in FIG. 2, as viewed from above. FIG. 6 is a cross-sectional view of the raising and lowering platform 30 of the stacker crane 1A illustrated in FIG. 2, as viewed from the right side.

The raising and lowering platform 30 allows an article M to be placed thereon (see FIG. 6) and is provided so as to be capable of being raised and lowered with respect to the masts 10. As illustrated in FIG. 5, the raising and lowering platform 30 includes a raising and lowering platform frame 31, a fork section 60, a turning section 70, and a cable box 37. The fork section 60 and the turning section 70 are mounted on the raising and lowering platform frame 31.

The raising and lowering platform frame 31 is provided with guide sections 32 that guide the raising and lowering platform 30 in the raising and lowering direction D2 in accordance with advance or retraction of the raising and lowering belts. The guide sections 32 have respective fixing parts 33 and respective guide shoes 35. One end of a corresponding one of the raising and lowering belts that are inserted through respective openings 34 which are formed in the respective fixing parts 33 is fixed to each of the fixing parts 33. Advance or retraction of the raising and lowering belts causes the fixing parts 33 to be pulled upward or lowered downward. The guide shoes 35 are engaged with the respective raising and lowering guide rails 11 of the masts 10 and slide with respect to the respective raising and lowering guide rails 11.

The fork section 60 loads or unloads the article M between the load shelf 2 and the raising and lowering platform 30. The fork section 60 is provided on a turning frame 71 of the turning section 70 (described later). The fork section 60 has a fork 61, arm sections 62, a gear box 65, and at least one fork motor unit 66. The fork 61 has a placement surface 611 (see FIG. 6) on which the article M can be placed. An upper surface of the fork 61 is the placement surface 611. The fork 61 is attached to the gear box 65.

The arm sections 62 are a pair of arm sections provided on the right and left. The fork 61 moves in an advance and retraction direction D4 (see FIG. 6) with respect to the raising and lowering platform 30 in accordance with movement of the arm sections 62 in the front-rear direction. The arm sections 62 have respective first arms 63 and respective second arms 64. On a first end 631 side in the longitudinal direction of a first arm 63, the first arm 63 is connected to the fork 61 via the gear box 65. The first arm 63 rotates about a rotation shaft A1 with respect to the gear box 65.

On a second end 632 side in the longitudinal direction of the first arm 63, the first arm 63 is connected to a second arm 64. In other words, the first arm 63 is provided on the first end 641 side in the longitudinal direction of the second arm 64. The first arm 63 rotates about a rotation shaft A2 with respect to the second arm 64.

On a second end 642 side in the longitudinal direction of the second arm 64, the second arm 64 is connected to a fork motor 67 (see FIG. 6) that the fork motor unit 66 has. The fork motor unit 66 is a driving section for moving the fork 61 in the advance and retraction direction D4. In a case where a driving force is transmitted from the fork motor 67, the second arm 64 rotates about a rotation shaft A3 with respect to the raising and lowering platform 30.

The at least one fork motor unit 66 comprises a plurality of fork motor units 66. The fork motor units 66 have respective fork motors 67 and respective encoders (not illustrated). In a case where the fork motors 67 rotate forward or backward, a pair of the second arms 64 rotate about respective rotation shafts A3. In a case where the second arms 64 rotate about the respective rotation shafts A3, first ends 641 of the respective second arms 64 move in a front or rear direction. A pair of the first arms 63 are each moved in the front-rear direction in accordance with movement of the first ends 641 of the respective second arms 64 in the front-rear direction. In this case, second ends 632 of the respective first arms 63 rotate with respect to the respective second arms 64, and first ends 631 of the respective first arms 63 rotate with respect to the gear box 65. The fork 61 is moved in the front-rear direction together with the gear box 65 in accordance with movement of the first ends 631 of the respective first arms 63 in the front-rear direction. In the present embodiment, the advance and retraction direction D4 of the fork 61 of the fork section 60 is the front-rear direction.

The turning section 70 turns the fork section 60 by rotating with respect to the raising and lowering platform 30. The turning section 70 has a turning frame 71 and a turning motor unit 75.

The turning frame 71 is a disk-shaped member and is provided with the fork section 60. As illustrated in FIG. 6, the turning frame 71 is connected to a rotation shaft A4 of a turning motor 76 of the turning motor unit 75. The turning motor unit 75 is a driving section that rotates the turning frame 71. The turning motor unit 75 has the turning motor 76 and an encoder (not illustrated). In a case where a driving force is applied to the turning frame 71 from the turning motor 76, the turning frame 71 rotates about the rotation shaft A4. In a case where the turning frame 71 rotates with respect to the raising and lowering platform 30, the fork section 60 turns in a turning direction D3 with respect to the raising and lowering platform 30.

A position of the fork section 60 (see FIG. 5) is a position that allows the article M to be loaded or unloaded on or from the load shelf 2 which is located in front of the stacker crane 1A. In a case where the turning frame 71 of the turning section 70 rotates 180 degrees from a position illustrated in FIG. 5, the fork section 60 turns with rotation of the turning frame 71. In a case where the fork section 60 turns 180 degrees from the position illustrated in FIG. 5, the fork section 60 allows the article M to be loaded or unloaded on or from the rear load shelf 2 which is located behind the stacker crane 1A.

The cable box 37 is a box in which cables for connecting (i) various devices mounted on the raising and lowering platform 30, such as a sensor(s), and (ii) a device(s) disposed outside the raising and lowering platform 30 are aggregated. The cable box 37 is disposed on the left side (home position HP1 side) with respect to the raising and lowering platform 30. Cables for communicating signals to the fork motor units 66 and the turning motor unit 75 each mounted on the raising and lowering platform 30 are aggregated in the cable box 37. The cable box 37 is provided with a connector plate in which a connector to which a raising and lowering cable is connected is installed. The connector of the cable box 37 is connected by the raising and lowering cable to a connector that is installed in a connector plate of the driver box 45.

[Control Box]

The control box 40 is attached to the first mast 10A. The control box 40 is attached to a rear side of the first mast 10A in the front-rear direction. The control box 40 is a housing that houses a control device 41 which carries out electronic control of the stacker crane 1A as a whole. The control device 41 is an example of a control section.

An electrical configuration of the stacker crane 1A will be described with reference to FIG. 8. FIG. 8 is a block diagram illustrating the electrical configuration of the stacker crane 1A illustrated in FIG. 2. As illustrated in FIG. 8, the control device 41 is constituted by a computer that includes a processor such as a central processing unit (CPU), a memory such as a RAM or a ROM, and a communication interface. The processor of the control device 41 carries out various types of control and various operations by executing various programs stored in the memory. The processor of the control device 41 mainly carries out control of traveling of the stacker crane 1A, control of raising and lowering of the raising and lowering platform 30, control of advance or retraction of the fork section 60, and control of turning of the turning section 70. The control device 41 is connected to a raising and lowering driver 46, a traveling driver 47, a fork driver 48, and a turning driver 49 so that information communication can be carried out. The raising and lowering driver 46 carries out control of motive power supplied to the raising and lowering motors 13. The traveling driver 47 carries out control of motive power supplied to the traveling motors 26. The fork driver 48 carries out control of motive power supplied to the fork motors 67. The turning driver 49 carries out control of motive power supplied to the turning motor 76.

The control device 41 controls each of the drivers 46 to 49. Specifically, the control device 41 transmits a command signal to each of the drivers 46 to 49 and controls operation of each of the drivers 46 to 49. More specifically, the control device 41 transmits a position command to each of the drivers 46 to 49. On the basis of the command signal from the control device 41, each of the drivers 46 to 49 outputs electric power to be supplied to a corresponding one of the motors 13, 26, 67, and 76.

Further, the control device 41 is electrically connected to the distance sensors 80, the bar code reader 81, and the emergency stop sensor 82. The control device 41 calculates a distance between the traveling guide rail 3 and the traveling vehicle 20 on the basis of signals acquired from the distance sensors 80. The control device 41 acquires position information read by the bar code reader 81, and controls the traveling driver 47 on the basis of the acquired position information. The control device 41 controls the traveling driver 47 on the basis of a signal acquired from the emergency stop sensor 82.

[Driver Box]

As illustrated in FIG. 2, the driver box 45 is attached to the first mast 10A. The driver box 45 is attached to a front side of the first mast 10A in the front-rear direction. The driver box 45 houses the raising and lowering driver 46, the traveling driver 47, the fork driver 48, and the turning driver 49. The drivers 46 to 49 are aggregated in one driver box 45. The fork driver 48 and the turning driver 49 are disposed outside the raising and lowering platform 30. The fork driver 48 and the turning driver 49 are connected to the cable box 37 of the raising and lowering platform 30 by a raising and lowering cable (not illustrated).

As illustrated in FIG. 8, the raising and lowering driver 46 is electrically connected to the raising and lowering motors 13. The raising and lowering driver 46 controls, on the basis of the command signal from the control device 41, an amount of electric current supplied to the raising and lowering motors 13. The raising and lowering driver 46 controls, on the basis of information fed back from an encoder (not illustrated) (an external encoder or a raising and lowering motor encoder), the amount of the electric current supplied to the raising and lowering motors 13. The raising and lowering driver 46 includes a driving circuit that supplies electric current to the raising and lowering motors 13.

The traveling driver 47 is electrically connected to the traveling motors 26. The traveling driver 47 controls, on the basis of the command signal from the control device 41, an amount of electric current supplied to the traveling motors 26. The traveling driver 47 controls, on the basis of information fed back from an encoder (not illustrated) (an external encoder or a traveling motor encoder), the amount of the electric current supplied to the traveling motors 26. The traveling driver 47 includes a driving circuit that supplies electric current to the traveling motors 26.

The fork driver 48 is electrically connected to the respective fork motors 67 of the fork motor units 66. The fork driver 48 controls, on the basis of the command signal from the control device 41, an amount of electric current supplied to the fork motors 67. The fork driver 48 controls, on the basis of information fed back from an encoder (not illustrated) that each of the fork motor unit 66 has, the amount of the electric current supplied to the fork motors 67. The fork driver 48 includes a driving circuit that supplies electric current to the fork motors 67.

The turning driver 49 is electrically connected to the turning motor 76 of the turning motor unit 75. The turning driver 49 controls, on the basis of the command signal from the control device 41, an amount of electric current supplied to the turning motor 76. Further, the turning driver 49 controls, on the basis of information fed back from an encoder (not illustrated) that the turning motor unit 75 has, the amount of the electric current supplied to the turning motor 76. The turning driver 49 includes a driving circuit that supplies electric current to the turning motor 76.

Note that, in the article transport facility 100, a configuration of the stacker crane 1B is similar to that of the stacker crane 1A, except for a part of the configuration. The following will describe the part of the configuration of the stacker crane 1B which part is different from the configuration of the stacker crane 1A. In the following description, wheels of the traveling vehicle 20 of the stacker crane 1B are referred to as a first driving wheel 1B22, a second driving wheel 1B23, a first driven wheel 1B24, and a second driven wheel 1B25, respectively. Further, a first side frame among frames constituting the vehicle frame 21 of the stacker crane 1B is referred to as a first side frame 1B211, and a second side frame among the frames constituting the vehicle frame 21 is referred to as a second side frame 1B212. Configurations of the wheels 1B22 to 1B25 of the stacker crane 1B, and the first side frame 1B211 and the second side frame 1B212 of the vehicle frame 21 are different from the configurations of the wheels 22 to 25 of the stacker crane 1A, and the first side frame 211 and the second side frame 212 of the vehicle frame 21.

A rail on which the first driving wheel 1B22 and the second driving wheel 1B23 of the traveling vehicle 20 of the stacker crane 1B roll is different from a rail on which the first driving wheel 22 and the second driving wheel 23 of the traveling vehicle 20 of the stacker crane 1A roll. That is, the first driving wheel 22 and the second driving wheel 23 of the stacker crane 1A roll on an upper surface of the traveling guide rail 3, and the first driving wheel 1B22 and the second driving wheel 1B23 of the stacker crane 1B roll on an upper surface of the traveling rail 4.

The first driving wheel 1B22 and the second driving wheel 1B23 are attached to the second side frame 1B212 of the traveling vehicle 20. Further, the first driven wheel 1B24 and the second driven wheel 1B25 of the stacker crane 1B are attached to the first side frame 1B211. The length in the right-left direction of the second side frame 1B212 to which the driving wheels are attached is longer than the length in the right-left direction of the first side frame 1B211 to which the driven wheels are attached. The first guide roller pair 28 and the second guide roller pair 29 of the stacker crane 1B are attached to the first side frame 1B211 as in the case of the first guide roller pair 28 and the second guide roller pair 29 of the stacker crane 1A.

Note that, as in the case of the stacker crane 1A, in the front-rear direction, the cable 90 of the stacker crane 1B is connected to the traveling vehicle 20 of the stacker crane 1B from behind the traveling rail 4 with the traveling rail 4 at the center between the front-side and rear-side regions. Note, however, that the present invention is not limited to such a configuration. In the front-rear direction, the cable 90 of the stacker crane 1B may be connected to the traveling vehicle 20 of the stacker crane 1B from the front of the traveling guide rail 3 with the traveling guide rail 3 at the center between the front-side and rear-side regions.

[Sensing by Control Device]

The control device 41 senses, on the basis of a horizontal distance detected by the first distance sensor 80A, that the first guide rollers 281 of the first guide roller pair 28 have been worn. Further, the control device 41 senses, on the basis of a horizontal distance detected by the second distance sensor 80B, that the second guide rollers 291 of the second guide roller pair 29 have been worn.

A case where the first guide rollers 281 of the first guide roller pair 28 have been worn will be used as an example to describe sensing of wear of the guide rollers by the control device 41. Note that sensing of wear of the second guide rollers 291 of the second guide roller pair 29 by the control device 41 is carried out as in the case of sensing of wear of the first guide rollers 281 of the first guide roller pair 28 by the control device 41.

Wear of one of the pair of first guide rollers 281 causes the traveling vehicle 20 to be highly unstable in the front-rear direction with respect to the traveling guide rail 3. That is, a distance between the first side frame 211 and the traveling guide rail 3 is greatly changed. For example, in a case where the front first guide roller 281 has been worn, a distance detected by the first distance sensor 80A between the first side frame 211 and the traveling guide rail 3 may be increased. In a case where the rear first guide roller 281 has been worn, the distance detected by the first distance sensor 80A between the first side frame 211 and the traveling guide rail 3 may be decreased. The control device 41 senses, from a change in horizontal distance detected by the first distance sensor 80A, that one of the pair of the first guide rollers 281 has been worn.

The first distance sensor 80A is provided near the first guide roller pair 28, and the second distance sensor 80B is provided near the second guide roller pair 29. This makes it possible to sense that a first guide roller of the first guide roller pair 28 has been worn and/or that a second guide roller of the second guide roller pair 29 has been worn.

The control device 41 senses a tilt of the traveling vehicle 20 on the basis of the horizontal distance detected by the first distance sensor 80A and the horizontal distance detected by the second distance sensor 80B. Specifically, on the basis of the horizontal distance detected by the first distance sensor 80A and the horizontal distance detected by the second distance sensor 80B, the control device 41 senses a tilt of the traveling vehicle 20 in the front-rear direction with respect to the traveling guide rail 3 during stopping of traveling.

Control by the control device 41 in a case where the traveling vehicle 20 that has been stopped is tilted with respect to the traveling guide rail 3 will be described with reference to FIG. 9. FIG. 9 is a view schematically describing tilts of the traveling vehicle 20, the raising and lowering platform 30, and the fork section 60 with respect to the traveling guide rail 3 when the stacker crane 1A is stopped.

The first guide rollers 281 and the second guide rollers 291 are elastic members. Thus, the first guide rollers 281 and the second guide rollers 291 are strained by a load applied in the front-rear direction. In a case where the first guide rollers 281 and/or the second guide rollers 291 are strained, the traveling vehicle 20 is in a state of being tilted obliquely in the front-rear direction with respect to the traveling guide rail 3. As illustrated in FIG. 9, when traveling of the stacker crane 1A is stopped, the traveling vehicle 20 may be in a state of being tilted obliquely in the front-rear direction with respect to the traveling guide rail 3. In a case where the traveling vehicle 20 is tilted in the front-rear direction with respect to the traveling guide rail 3, the raising and lowering platform 30 is also tilted obliquely in the front-rear direction with respect to the traveling guide rail 3 in accordance with the tilt of the traveling vehicle 20.

On the basis of the horizontal distance detected by the first distance sensor 80A and the horizontal distance detected by the second distance sensor 80B, the control device 41 calculates a tilt of the traveling vehicle 20 with respect to the traveling guide rail 3 and senses the tilt of the traveling vehicle 20. The control device 41 controls the turning section 70 in accordance with the sensed tilt of the traveling vehicle. Specifically, the control device 41 drives the turning motor 76 so as to rotate the turning frame 71 in a direction opposite from a direction of the tilt of the traveling vehicle 20 with respect to the traveling guide rail 3 in the front-rear direction. For example, in a case where the traveling vehicle 20 is tilted in the direction indicated by an arrow A, the control device 41 can advance or retract the fork 61 of the fork section 60 perpendicularly with respect to the load shelves 2 by rotating the turning frame 71 in a direction of an arrow B.

The above configuration enables the first distance sensor 80A and the second distance sensor 80B to detect the tilt of the traveling vehicle 20 with respect to the traveling guide rail 3. With this, in a case where a first guide roller and/or a second guide roller is/are strained, it is possible to accurately sense the tilt of the traveling vehicle with respect to the traveling guide rail 3.

Further, according to the above configuration, driving of the turning section 70 is controlled in accordance with the tilt of the traveling vehicle. This prevents an article from being loaded or unloaded in a state in which the fork section is tilted with respect to a load shelf by the tilt of the traveling vehicle. This makes it possible to accurately load or unload the article on or from the load shelf.

Embodiment 2

The following will describe another embodiment of the present invention in detail with reference to FIGS. 10 and 11. Note that for convenience, members having functions identical to those of the respective members described in Embodiment 1 are given respective identical reference numerals, and a description of those members is omitted. A traveling vehicle 20A of a stacker crane 1A in accordance with Embodiment 2 is different from the traveling vehicle 20 of the stacker crane 1A in accordance with Embodiment 1 in that a first driving wheel 22A is traveling on a traveling rail 4.

FIG. 10 is a plan view of the stacker crane 1A of an article transport facility 100A in accordance with Embodiment 2 of the present invention, as viewed from above. FIG. 11 provides (i) a cross-sectional view taken at a central position CL illustrated in FIG. 10 and (ii) a cross-sectional view taken along line A-A illustrated in FIG. 10. A reference sign 200 in FIG. 11 shows the cross-sectional view taken at the central position CL illustrated in FIG. 10. A reference sign 201 in FIG. 11 shows the cross-sectional view taken along line A-A illustrated in FIG. 10.

As illustrated in FIG. 10, the first driving wheel 22A of the stacker crane 1A is attached to a second side frame 212A and rolls on an upper surface of the traveling rail 4. The first driving wheel 22A is located on a left end portion side of the second side frame 212A when viewed from a central position CL in a right-left direction of a vehicle frame 21. The first driving wheel 22A is located on a left side of a first connection frame 213 in the right-left direction. A first traveling motor 26A of the stacker crane 1A is provided to the second side frame 212A. More specifically, the first traveling motor 26A is located on the left end portion side of the second side frame 212A when viewed from the central position CL in the right-left direction of the vehicle frame 21.

A first driven wheel 24A of the stacker crane 1A is attached to a first side frame 211A and rolls on an upper surface of a traveling guide rail 3. The first driven wheel 24A is located on a left end portion side of the first side frame 211A. The first driven wheel 24A is located on a right side of the first driving wheel 22A in the right-left direction.

Note that the first driving wheel 22A and the first traveling motor 26A may be located on the right side of the second side frame 212A when viewed from the central position CL in the right-left direction of the vehicle frame 21. That is, the first driving wheel 22A and the second driving wheel 23 may be located at an identical position on the left side or the right side in the right-left direction without being spaced apart from each other in the right-left direction.

A first distance sensor 80A is attached to a position closer to the first driven wheel 24A than a second distance sensor 80B. Specifically, a distance L1 in the right-left direction between the first distance sensor 80A and a first guide roller pair 28 is shorter than a distance L5 in the right-left direction between the first distance sensor 80A and the first driven wheel 24A. More specifically, the distance L5 is a distance in the right-left direction between the first distance sensor 80A and a center of a rotation axis of the first driven wheel 24A.

Further, a bar code reader 81A is attached to the first side frame 211A of the traveling vehicle 20A. The bar code reader 81A reads a bar code 83A provided on a front side surface of a traveling guide rail 3A. The bar code 83A includes position information that is information pertaining to a position in a longitudinal direction of the traveling guide rail 3A. The stacker crane 1A of the present embodiment moves to each transport position CP1 on the basis of the position information read from the bar code 83A of the traveling guide rail 3A. Note that, in place of the bar code reader 81A, a reader that reads a scale provided on a side surface of the traveling guide rail 3A may be attached.

Further, motive power is supplied to the stacker crane 1A of the article transport facility 100A in accordance with the present Embodiment 2 in a noncontact manner. As shown by the reference sign 200 in FIG. 11, the article transport facility 100A includes a guidepath wire 95. The guidepath wire 95 is disposed in parallel with the traveling rail 4. The guidepath wire 95 is an example of a feed section. To the guidepath wire 95, electric power is supplied from a power panel (not illustrated).

A pickup coil 96 is attached to the traveling vehicle 20A of the stacker crane 1A. The pickup coil 96 is an example of a power receiving section. The pickup coil 96 is disposed at a distance from the guidepath wire 95 so as to face the guidepath wire 95. The pickup coil 96 receives electric power from a magnetic field generated from the guidepath wire 95.

As shown by the reference sign 201 in FIG. 11, the traveling rail 4 is provided with a metallic ground rail 5. More specifically, the ground rail 5 extends frontward from a lower end portion of a front side surface of the traveling rail 4. A ground roller 55 is attached to the second side frame 212A of the traveling vehicle 20A. The ground roller 55 is made of an electrically conductive member. The ground roller 55 rolls on an upper surface of the ground rail 5. The ground roller 55 is a roller that has a function as a ground and that is additionally installed separately from a wheel of the traveling vehicle 20A.

Aspects of the present invention can also be expressed as follows:

An article transport device in accordance with a first aspect of the present invention includes a traveling vehicle, the traveling vehicle having: a first wheel; a second wheel that is disposed so as to be spaced apart from the first wheel in a traveling direction, which is a direction along a guide rail; a first guide roller pair that has a pair of first guide rollers between which the guide rail is sandwiched in a direction intersecting the traveling direction; a second guide roller pair that has a pair of second guide rollers between which the guide rail is sandwiched in the direction intersecting the traveling direction and that is disposed so as to be spaced apart from the first guide roller pair in the traveling direction; a frame in which the traveling direction is a longitudinal direction and to which the first guide rollers and the second guide rollers are attached; a first sensor which detects a horizontal distance between the frame and the guide rail; and a second sensor which is disposed so as to be spaced apart from the first sensor in the traveling direction and which detects the horizontal distance between the frame and the guide rail, the first sensor and the second sensor each being attached to the frame, the first guide roller pair being located closer to the first wheel than the second guide roller pair and the second sensor in the traveling direction, the first sensor being located closer to the first wheel than the second guide roller pair and the second sensor in the traveling direction, a distance between the first sensor and the first guide roller pair in the traveling direction being shorter than a distance between the first sensor and the first wheel in the traveling direction, and a distance between the second sensor and the second guide roller pair in the traveling direction being shorter than a distance between the second sensor and the second wheel in the traveling direction.

According to the article transport device in accordance with the first aspect, the first sensor is provided near the first guide roller pair, and the second sensor is provided near the second guide roller pair. This makes it possible to sense that a first guide roller of the first guide roller pair has been worn and/or that a second guide roller of the second guide roller pair has been worn.

In a second aspect of the present invention, the article transport device may be configured, in the first aspect, such that the first guide roller pair and the second guide roller pair are located between the first wheel and the second wheel in the traveling direction. According to the article transport device in accordance with the second aspect, the first guide roller pair and the second guide roller pair are provided in an empty space between the first wheel and the second wheel. This makes it possible to provide the first guide roller pair and the second guide roller pair to a frame of the traveling vehicle without any constraint imposed by other members.

In a third aspect of the present invention, the article transport device is configured, in the first or second aspect, such that the first sensor and the second sensor are located between the first wheel and the second wheel in the traveling direction. According to the article transport device in accordance with the third aspect, the first sensor and the second sensor may be configured to be installed in an empty space between the first wheel and the second wheel. This makes it possible to attach the first distance sensor and the second distance sensor to the frame of the traveling vehicle without any constraint imposed by other members.

In a fourth aspect of the present invention, the article transport device is configured, in any one of the first to third aspects, such that the first wheel and the second wheel are each a driving wheel that is driven by motive power from a driving source. According to the article transport device in accordance with the fourth aspect, the guide rail on which the first wheel and the second wheel, which are driving wheels, travel is sandwiched by the first guide roller pair and the second guide roller pair. This allows the traveling vehicle to easily travel straight in the traveling direction by the first guide roller pair and the second guide roller pair. This makes it possible to improve straight traveling performance of the traveling vehicle.

In a fifth aspect of the present invention, the article transport device is configured, in any one of the first to fourth aspects, to further include a control section that senses a tilt of the traveling vehicle on the basis of the horizontal distance detected by the first sensor and the horizontal distance detected by the second sensor. According to the article transport device in accordance with the fifth aspect, the tilt of the traveling vehicle with respect to the guide rail can be detected by the first sensor and the second sensor. With this, in a case where a first guide roller and/or a second guide roller is/are strained, it is possible to accurately sense the tilt of the traveling vehicle with respect to the guide rail.

In a sixth aspect of the present invention, the article transport device is configured, in any one of the first to fifth aspects, such that the first sensor and the second sensor are attached to the frame on opposite sides in the traveling direction when viewed from a central position in the traveling direction. The article transport device in accordance with the sixth aspect makes it possible to widen a distance between (a) the first sensor that is located on one side from the central position in the traveling direction of the frame and (b) the second sensor that is located on the other side from the central position in the traveling direction of the frame. This makes it possible to more accurately detect a tilt of a traveling vehicle with respect to a guide rail.

In a seventh aspect of the present invention, the article transport device is configured, in the fifth or sixth aspect, to further include: a mast that is erected on the traveling vehicle; a raising and lowering platform that is provided so as to be capable of being raised and lowered with respect to the mast; a fork section that is mounted on the raising and lowering platform and that loads or unloads an article between a load shelf and the raising and lowering platform by moving in an advance and retraction direction; and a turning section that turns the fork section, the control section controlling driving of the turning section in accordance with the tilt of the traveling vehicle which tilt has been sensed from detection results from the first sensor and the second sensor.

According to the article transport device in accordance with the seventh aspect, driving of the turning section is controlled in accordance with the tilt of the traveling vehicle. This prevents an article from being loaded or unloaded in a state in which the fork section is tilted with respect to a load shelf by the tilt of the traveling vehicle. This makes it possible to accurately load or unload the article on or from the load shelf.

[Additional Remarks]

The present invention is not limited to the embodiments, but can be altered by a skilled person in the art within the scope of the claims. The present invention also encompasses, in its technical scope, any embodiment derived by combining technical means disclosed in differing embodiments.

REFERENCE SIGNS LIST

- 1 Stacker crane
- 3 Traveling guide rail
- 4 Traveling rail
- 10 Mast
- 20 Traveling vehicle
- 21 Vehicle frame
- 22 First driving wheel
- 23 Second driving wheel
- 28 First guide roller pair
- 29 Second guide roller pair
- 41 Control device
- 80 Distance sensor
- 81 Bar code reader
- 100 Article transport facility
- 281 First guide roller
- 291 Second guide roller

ARTICLE TRANSPORT DEVICE

Information

Publication Number

Date Filed

Date Published

Inventors

Original Assignees

CPC

International Classifications

Abstract

Description

Claims

Priority Claims (1)