Stacker crane

A stacker crane includes a first covering body covering a sliding section of a mast and an ascending and descending unit, and providing a first space extending vertically along the mast, a second covering body providing a second space extending vertically along the mast and partitioned from the first space by a first barrier, a plurality of exhaust holes that are vertically dispersed in the first barrier and cause the first space and the second space to be in communication, and an exhaust device that is attached to the mast and expels air in the second space at a portion in a vertical direction.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to stacker cranes that travels along shelves storing loads and transfer loads between shelves.

2. Description of the Related Art

In, for example, industrial establishments that handle a large number of loads, loads are stored vertically and horizontally on shelves, and placing and removal of the loads is automated using a stacker crane that moves along the shelves.

With stacker cranes used in clean rooms, it is difficult to reduce the amount of dust generated at the sliding section because the sliding section is large, so sometimes implementations to remove the dust generated at the sliding section are devised.

For example, Japanese Unexamined Patent Application Publication No. 2008-74542 discloses a technique for capturing dust in a stacker crane having a long mast designed for tall, vertically stacked shelves and a covered area behind the mast where a chain for driving the ascending and descending unit rotates. The dust generated throughout the entire mast is captured by drawing in the air in the covered area with a plurality of fan filter units installed in top and bottom ends of the covered area.

However, with the sort of conventional technique disclosed in Japanese Unexamined Patent Application Publication No. 2008-74542, the longer the overall length of the mast is, the greater number of fan filter units are required to be attached to the mast, thus increasing the weight of the stacker crane, which necessitates more power to operate the stacker crane.

SUMMARY OF THE INVENTION

Preferred embodiments of the present invention provide a stacker crane that efficiently captures dust generated from a mast of a stacker crane, throughout an entire area of the mast, and significantly reduces or prevents spreading of dust inside a clean room.

A stacker crane according to a preferred embodiment of the present invention includes a travel unit that moves along a shelf that stores a load, a transfer unit that transfers the load to the shelf, a mast extending vertically and attached to the travel unit, and an ascending and descending unit that slides along the mast and moves the transfer unit vertically. The stacker crane includes a first covering body covering a sliding section of the mast and the ascending and descending unit, and defining a first space extending vertically along the mast; a second covering body defining a second space extending vertically along the mast, the second space being partitioned from the first space by a first barrier; a plurality of exhaust holes that are vertically dispersed in the first barrier to cause the first space and the second space to be in communication; and an exhaust device that is attached to the mast, and expels air in the second space, at a portion in a vertical direction.

With this unique structure, the exhaust device expels the air in the second space at a portion in a vertical direction along the mast, and the air in the first space is drawn into the second space via a plurality of exhaust holes dispersed vertically along the mast. In other words, negative pressure in the second space generated by the exhaust device is even throughout the vertical direction along the mast, such that the air in the first space is drawn in evenly or substantially evenly throughout the vertical direction. Thus, airborne dust in the first space is efficiently captured with a single exhaust device throughout the entire wide range in the vertical direction. Thus, dust generated from the sliding section throughout the length of the mast is efficiently captured by a small number of exhaust devices.

The stacker claim may further include a second barrier that extends vertically and defines a third space and a fourth space by horizontally partitioning the first space. The exhaust device may include an intake port located nearer the third space than the fourth space, the plurality of exhaust holes may include a plurality of first exhaust holes that cause the third space and the second space to be in communication and a plurality of second exhaust holes that cause the fourth space and the second space to be in communication, and an airflow resistance of the plurality of first exhaust holes may be higher than an airflow resistance of the plurality of second exhaust holes.

With this unique structure, regardless of where the exhaust device is attached at the perimeter of the mast, airborne dust in the first space is able to be captured evenly and efficiently. Accordingly, the degree of freedom regarding attachment of the exhaust device to the stacker crane (i.e., the design freedom) increases.

Moreover, the exhaust device may be disposed between the mast and the shelf.

With this unique structure, the travel distance of the stacker crane within the limited installation area is able to be significantly increased or maximized.

Moreover, a guiding space that is in communication with the second space and an intake port of the exhaust device may be provided between the mast and the exhaust device.

With this unique structure, the performance ability of the exhaust device is effectively utilized.

Various preferred embodiments of the present invention provide a stacker crane that efficiently captures dust generated at, for example, the sliding section of the mast, throughout the entire vertical area of the mast, and does not contaminate, for example, a clean room with dust from the mast.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Next, stacker cranes according to preferred embodiments of the present invention will be described with reference to the Drawings. Note that the following preferred embodiments are merely examples of the stacker cranes according to the present invention. As such, the scope of the present invention is defined by the scope of the language in the appended claims, using the below preferred embodiments as references, and is not intended to be limited merely by the following preferred embodiments. Accordingly, among the elements in the following preferred embodiments, those not recited in any one of the independent claims defining the most generic aspects of the inventive concept are described as being used to achieve a preferred embodiment of the present invention, and are not absolutely necessary to overcome the problem described herein.

FIG. 1is a partial view of an automated warehouse system including a stacker crane and shelves.

FIG. 2is a plan view of an automated warehouse system from the top.

As illustrated in these figures, the automated warehouse system200includes two shelves201disposed parallel or substantially parallel to one another and a stacker crane100disposed between the two shelves201. In this preferred embodiment, the automated warehouse system200preferably is a warehouse system used, for example, in a clean room, and places and stores the loads202on the shelves201.

The shelves201align and store loads202in a vertical direction (along the Z axis in the Drawings) and in one horizontal direction (along the X axis in the figures), and allows for loads202to be individually placed and removed in another horizontal direction (along the Y axis in the Drawings).

In this preferred embodiment, the shelves201preferably include support bodies attached so as to protrude horizontally relative to pillars extending vertically, and the loads are placed on these support bodies.

The stacker crane100preferably is a crane including a travel unit101that moves along shelves201that store loads202, a transfer unit102that transfers the loads202to the shelves201, a mast103extending vertically and attached to the travel unit101, and an ascending and descending unit104that slides along the mast103and moves the transfer unit102vertically, and also includes a first covering body105, a second covering body106, exhaust holes136(for example, seeFIG. 3andFIG. 4), and an exhaust device107.

The stacker crane100is able to move the transfer unit102in front of any given load202stored on a shelf201by moving the travel unit101left and right (along the X axis in the Drawings) and moving the ascending and descending unit104vertically along the mast103(along the Z axis in the Drawings). In other words, the stacker crane100can remove any given load from a shelf201and place a load202in any given location on a shelf201. More specifically, a controller automatically controls operation of the transfer unit102.

The travel unit101preferably is a trolley that moves along the shelves201that store the loads202, and causes the stacker crane100to travel horizontally (along the X axis in the Drawings). In this preferred embodiment, the travel unit101includes, for example, a motor, and also includes a lower trolley112that travels horizontally on a lower rail111on the floor of a room, and an upper trolley114that travels horizontally on an upper rail113disposed high in the room.

The transfer unit102is a device that transfers loads202between a shelf201and the stacker crane100. In this preferred embodiment, the transfer unit102preferably uses SCARA technology to transfer loads202with a multi-jointed arm unit. The transfer unit102is able to transfer a load202between shelves201even in a narrow space by rotating the joints of the arm unit.

The ascending and descending unit104includes an ascending and descending platform141that is attached to the mast103in a manner that allows it to slide vertically along the mast103and has the transfer unit102attached thereto, an ascending and descending motor (not shown in the figures) to vertically drive the ascending and descending platform141, and a transmission component142(seeFIG. 3andFIG. 4) such as a chain that transmits the driving power generated by the motor to the ascending and descending platform141.

The mast103is a rod-shaped structural component which extends vertically (along the Z axis in the Drawings), and to which the travel unit101is attached. Following the movement of the travel unit101, the mast103moves parallel or substantially parallel to a horizontal direction (parallel to the X axis in the Drawings). The mast103includes a sliding section134along which the ascending and descending platform141slides, and a sprocket (not shown in the figures), for example, is attached to the upper portion of the mast103and supports the transmission component142.

FIG. 3is a cross sectional view of an imaginary cut made through the mast along line A-A inFIG. 1.

FIG. 4is a cross sectional view of an imaginary cut made through the mast along line B-B inFIG. 1.

FIG. 5is a perspective view from the negative direction of the X axis of the portion of the mast where the exhaust device is attached.

FIG. 6is a perspective view from the positive direction of the X axis of the portion of the mast where the exhaust device is attached.

As illustrated in these figures, the mast103according to this preferred embodiment includes a rectangular or substantially rectangular, plate-shaped core section133elongated in the traveling direction of the stacker crane100(along the X axis in the Drawings) that is disposed in the central portion of the mast103, a rectangular or substantially rectangular, plate-shaped first wall section131and a rectangular or substantially rectangular, plate-shaped second wall section132that are parallel or substantially parallel to the core section133and disposed so as to sandwich the core section133, and a connecting section135that connects the first wall section131and the core section133in a bridge-like manner. Moreover, a first barrier181that connects the second wall section132and the core section133in a bridge-like manner is attached to the mast103. Note that in addition to being a structural section of the mast103, the connecting section135also defines and functions as the first barrier181that partitions the first space191and the second space192.

Moreover, the end of the core section133in the traveling direction includes the sliding section134. The first wall section131and the second wall section132of the mast103have wider traveling direction (X axis directions in the Drawings) widths than the core section133, and the sliding section134is disposed in a region sandwiched by the first wall section131and the second wall section132, fit into place.

Moreover, the first wall section131, the core section133, and the connecting section135define a sack-shaped section (e.g., a C-shaped or square C-shaped section). Moreover, no connection section corresponding to the connecting section135is present between the core section133and the second wall section132.

Note that inFIG. 3andFIG. 4, the first wall section131, the second wall section132, the core section133, and the connecting section135of the mast103, for example, preferably are illustrated as having a solid core, but the structure of the mast103is not particular limited, and may be formed of hollow components or a truss frame with thin plates attached thereto. Moreover, the cross sectional shape of the mast103is not particularly limited.

The first covering body105is a plate-shaped component that defines the first space191extending vertically along the mast103, and covers the sliding section134of the mast103and the ascending and descending platform141of the ascending and descending unit104.

In this preferred embodiment, the first covering body105is attached so as to provide a bridge between an end of the first wall section131in the traveling direction (the end in the negative direction of the X axis in the Drawings) and an end of the second wall section132in the traveling direction (the end in the negative direction of the X axis in the Drawings), and has a vertically extending slit153in a central portion for the ascending and descending platform141to pass through. More specifically, the first covering body105includes a left covering body151that extends from the first wall section131toward the core section133, and a right covering body152that extends from the second wall section132toward the core section133, and the gap between the left covering body151and the right covering body152is the slit153. Here, “cover” does not only mean completely covering; the meaning as used here includes the presence of gaps (slit153) or holes of a size that generate airflow resistance.

The first space191is a space surrounded by the mast103, the first covering body105, and the first barrier181(including the connecting section135), and extends vertically in a long, pillar shape along the mast103. Note that “space” does not mean a space that is completely closed off; the meaning as used here refers to a region enclosed by components to a degree that airflow resistance is generated when air travels from one space to another.

The second covering body106is a plate-shaped component that defines the second space192which is partitioned from the first space191by the first barrier181and extends vertically along the mast103.

In this preferred embodiment, the second covering body106is attached so as to provide a bridge between an end of the first wall section131in the traveling direction (the end in the positive direction of the X axis in the Drawings) and an end of the second wall section132in the traveling direction (the end in the positive direction of the X axis in the Drawings), and extends vertically, as illustrated inFIG. 4andFIG. 6. Moreover, the section of the second covering body106where a duct171that guides air to the exhaust device107is attached is opened so as to allow air to flow from the second space192.

The second space192is a space surrounded by the mast103and the second covering body106, and extends vertically in a long, pillar shape along the mast103.

The air in the second space192is expelled by the exhaust device107, and the second space192has a more negative air pressure than the first space191(including the third space193and the fourth space194). Moreover, the air in the second space192, which extends a long distance vertically, is expelled in a portion of the second space192, but the second space192is designed such that the air throughout the vertical direction is capable of having an even negative pressure or substantially even negative pressure. Although the reason is not clear at this point in time, this is believed to be attributed to the fact that the second space192is smaller in volume than the first space191and negative air pressure generated by the exhaust device107expelling air is able to be caused to propagate rapidly in the vertical directions.

In this preferred embodiment, the transmission component142that transmits driving power to vertically drive the ascending and descending platform141of the ascending and descending unit104rotates through the second space192.

Exhaust holes136are holes that are vertically dispersed in the first barrier181and place the first space191and the second space192in communication.

In this preferred embodiment, the first space191is partitioned into the third space193and the fourth space194by the core section133of the mast103, which also defines and functions as the second barrier182, and exhaust holes136which cause the second space192and the third space193to be in communication and exhaust holes136which cause the second space192and the fourth space194to be in communication are provided. Hereinafter, in order to distinguish between these exhaust holes136, the exhaust holes136that are in communication with the third space193may be referred to as first exhaust holes137, and the exhaust holes136that are in communication with the fourth space194may be referred to as second exhaust holes138.

Moreover, in this preferred embodiment, the airflow resistance of the first exhaust holes137is set to be higher than the airflow resistance of the second exhaust holes138. With this, the air in the third space193and the air in the fourth space194is able to be expelled evenly or substantially evenly, making it possible to evenly draw in dust. Note that the method of setting the difference in airflow resistances is not limited to a particular method; for example, the area of each opening of the first exhaust holes137is able to be set smaller than the area of each opening of the second exhaust holes138, the total number of the first exhaust holes137s is able to be set lower than the total number of the second exhaust holes138, or the total area of the openings of the first exhaust holes137is able to be set to be smaller than the total area of the openings of the second exhaust holes138. Moreover, the openings of the exhaust holes136disposed vertically (including the first exhaust holes137and the second exhaust holes138) may have different size areas. More specifically, the area of the openings of the exhaust holes136near the exhaust device107may be set small, and the area of the openings of the exhaust holes136may be set so as to increase with distance from the exhaust device107.

Here, the third space193is a space to the side near the intake port172of the exhaust device107. Moreover, in this preferred embodiment, the third space193is a space through which electrical equipment, such as cables that receive control signals and supplying power to the transfer unit102attached with the ascending and descending unit104, is routed, and as such, dust generated by, for example, cables rubbing against something, may become airborne.

The fourth space194is a space to the side farther from the intake port172of the exhaust device107. In this preferred embodiment, the fourth space194is a space through which the transmission component142that transmits driving power to vertically drive the ascending and descending platform141of the ascending and descending unit104rotates through, and is a space in which dust may generate from the transmission component142such as a chain or from a sprocket, for example.

The exhaust device107is a device that is attached to the mast103, and expels the air in the second space192, at a portion of the second space192in the vertical direction.

In this preferred embodiment, the exhaust device107preferably is a fan filter unit which includes a fan173that draws in air and a filter174that removes dust from the drawn in air. Moreover, the exhaust device107is disposed between the mast103and a shelf201, in other words, is attached to a side surface of the mast103relative to the traveling direction of the stacker crane100, and a duct171is attached to the exhaust device107to guide the air in the second space192to the exhaust device107.

The duct171is a component that defines a guiding space175that guides the air in the second space192to the exhaust device107.

In this preferred embodiment, the exhaust device107is attached such that a portion of the intake port172protrudes from an end of the mast103in the traveling direction (the end in the positive direction of the X axis the Drawings) and another portion of the intake port172faces the mast103. As a result, the duct171is shaped such that the guiding space175is also provided between the exhaust device107and the portion of the mast103that faces the exhaust device107. In other words, the guiding space175defined by the duct171has a key shape (L shape) in a horizontal plane (in the XY plane in the Drawings). By providing the duct171with this sort of shape, even when the exhaust device107is attached to a side in a direction intersecting the direction in which the first space191and the second space192are aligned, loss of the expelling ability of the exhaust device107deriving from the position of the exhaust device107is able to be significantly reduced or kept to a minimum.

With the stacker crane100described above, the vertical length at which a single exhaust device107is able to evenly or substantially evenly draw in air in the first space191is able to be lengthened. Accordingly, even when the length of the mast103of the stacker crane100is increased, the number of exhaust devices107to be attached is able to be reduced, and airborne dust in the first space191is able to be efficiently captured with less energy. Thus, throughout the entire length of the mast103, dust is able to be effectively prevented from escaping, making it possible to achieve a stacker crane100suitable for use in a clean room.

Note that the present invention is not limited to the above preferred embodiments. For example, preferred embodiments resulting from arbitrary combinations of constituent elements described in the present specification or preferred embodiments in which some constituent elements are left out may also be preferred embodiments of the present invention. The present invention also includes variations of the above preferred embodiments conceived by those skilled in the art unless they depart from the spirit and scope of the present invention, that is, the language in the claims.

For example, the automated warehouse system200is exemplified as preferably being used in a clean room, but may be used in, for example, a depository for temporarily storing various loads in a distribution warehouse.

Moreover, the transfer technique used by the transfer unit102is not limited to SCARA technology; for example, fork or push-pull techniques may be used.

Moreover, the shapes of the first covering body105and the second covering body106are not limited to flat plate shapes; for example, the first covering body105and the second covering body106may be bent as illustrated inFIG. 7, or curved.

Moreover, the exhaust device107may be attached on a side in the traveling direction (along the X axis in the Drawings). In this case, the airflow resistance of the first exhaust holes137, which are, in this case, located relatively close to the intake port172of the exhaust device107, may be set higher than the airflow resistance of the second exhaust holes138, which are, in this case, located farther than the first exhaust holes137.

Moreover, the exhaust device107is not limited to a fan filter unit; for example, the exhaust device107may include an exhaust fan and may expel the air from the exhaust fan out of the clean room via a duct.

Preferred embodiments of the present invention are applicable in, for example, automated warehouse systems installed in industrial establishments requiring a clean space.