Article transport facility

Patent metadata

Field	Value
Publication number	US-12084093-B2
Application number	US-202117395538-A
Country	US
Kind code	B2
Filing date	Aug 6, 2021
Priority date	Aug 7, 2020
Publication date	Sep 10, 2024
Grant date	Sep 10, 2024

Abstract

A travel unit travels in a curved section in an orientation in which a target wheel comes into contact with a target rail, a guide wheel comes into contact with a guide rail, and a non-target wheel does not come into contact with a non-target rail. The control unit changes the rotational speed of a first wheel and a second wheel in the curved section relative to the rotational speed of the first wheel and the second wheel in a straight section in accordance with the ratio of a second length, which is the length of the target rail along a travel path, to a first length, which is the length of the curved section along the travel path at a center portion in a widthwise direction of the travel path.

First claim

What is claimed is:

1. An article transport facility comprising:
travel rails arranged along a travel path;
a transport vehicle configured to travel along the travel rails and transport an article; and
a control unit configured to control a traveling operation of a travel unit included in the transport vehicle,
wherein:
the travel path includes a straight section that is formed in a straight shape in a plan view, and a curved section that is formed in a curved shape in a plan view,

in the straight section, a first travel rail and a second travel rail among the travel rails are arranged separately on respective sides of a center portion in a widthwise direction of the travel path and, in the curved section, with one out of the first travel rail and the second travel rail being a target rail and the other one being a non-target rail, at least the target rail, out of the target rail and the non-target rail, is arranged along the travel path, and a guide rail that is different from the target rail and the non-target rail is also arranged along the travel path,
the travel unit includes a first wheel configured to roll on a traveling surface of the first travel rail, a second wheel configured to roll on a traveling surface of the second travel rail, a drive unit configured to rotate the first wheel and the second wheel at the same speed, and a guide wheel configured to roll on a guide surface of the guide rail,
when a target wheel is the first wheel when the target rail is the first travel rail, and when the target wheel is the second wheel when the target rail is the second travel rail, and a non-target wheel is whichever one of the first wheel and the second wheel is not the target wheel,
the travel unit travels in the curved section in an orientation in which the target wheel comes into contact with the target rail, the guide wheel comes into contact with the guide rail, and the non-target wheel does not come into contact with the non-target rail, and
the control unit changes a rotational speed of the first wheel and the second wheel in the curved section relative to a rotational speed of the first wheel and the second wheel in the straight section in accordance with a ratio of a second length, which is a length of the target rail along the travel path, to a first length, which is a length of the curved section along the travel path at the center portion in the widthwise direction of the travel path.

2. The article transport vehicle according to claim 1 ,
wherein the control unit sets the rotational speed of the first wheel and the second wheel in the curved section in a case of traveling at a set speed, to a speed obtained by multiplying the rotational speed of the first wheel and the second wheel in a case of traveling in the straight section at the set speed by a value obtained by dividing the second length by the first length.

3. The article transport vehicle according to claim 1 ,
wherein the control unit starts changing the rotational speed of the first wheel and the second wheel in accordance with a timing at which the travel unit enters the curved section from the straight section and a timing at which the travel unit enters the straight section from the curved section.

4. The article transport vehicle according to claim 1 ,
wherein when changing the rotational speed of the first wheel and the second wheel between the rotational speed in the straight section and the rotational speed in the curved section, the control unit changes the rotational speed of the first wheel and the second wheel such that a first-order differential value of the rotational speed is constant.

5. The article transport vehicle according to claim 1 ,
wherein when changing the rotational speed of the first wheel and the second wheel between the rotational speed in the straight section and the rotational speed in the curved section, the control unit changes the rotational speed of the first wheel and the second wheel such that a second-order differential value of the rotational speed is constant.

6. The article transport vehicle according to claim 1 , wherein:
a detected body is provided at a position corresponding to a boundary between the straight section and the curved section in the travel path, and an information holder is provided at a position on an upstream side of the travel path with respect to the boundary, the information holder holding address information indicating the position,
the transport vehicle includes a detection device configured to detect the detected body, a reading device configured to read the address information held by the information holder, and a measuring device configured to measure a travel distance of the travel unit,
a region extending along the travel path on both sides of the boundary is a boundary region,
the control unit derives an estimated current position that is a current estimated position of the travel unit based on the address information read by the reading device and the travel distance measured by the measuring device, and determines that the travel unit has reached the boundary and starts changing the rotational speed of the first wheel and the second wheel if a first condition or a second condition is satisfied,
the first condition is that the estimated current position is a position within the boundary region, and that the detected body has been detected by the detection device, and
the second condition is that, after the estimated current position entered the boundary region, the estimated current position has reached an end portion of the boundary region on a downstream side of the travel path without the detected body being detected by the detection device.

7. The article transport vehicle according to claim 1 , wherein:
when the travel unit is a first travel unit, the transport vehicle includes a second travel unit arranged on a front side in a front-back direction along the travel path with respect to the first travel unit, and a main body portion connected to the first travel unit and the second travel unit,
the first travel unit is connected to the main body portion so as to be rotatable about a first axis parallel to the vertical direction,
the second travel unit is connected to the main body portion so as to be rotatable about a second axis parallel to the vertical direction,
assuming that the guide wheel is a first guide wheel, the second travel unit includes a third wheel configured to roll on the traveling surface of the first travel rail, a fourth wheel configured to roll on the traveling surface of the second travel rail, and a second guide wheel configured to roll on the guide surface of the guide rail,
the control unit controls the rotational speed of the first wheel and the second wheel so as to adjust the rotational speed to a target rotational speed, and causes the second travel unit to travel following the traveling of the first travel unit,
when the target wheel is a first target wheel and the non-target wheel is a first non-target wheel, a second target wheel is the third wheel when the first wheel is the first target wheel, the second target wheel is the fourth wheel when the second wheel is the first target wheel, and a second non-target wheel is whichever one of the third wheel and the fourth wheel is not the second target wheel,
the second travel unit travels in the curved section in an orientation in which the second target wheel comes into contact with the target rail, the second guide wheel comes into contact with the guide rail, and the second non-target wheel does not come into contact with the non-target rail, and
the control unit determines that the first travel unit has reached the boundary between the straight section and the curved section in the travel path and starts changing the rotat

Assignees

• Daifuku Kk

Inventors

• Otsuka Hiroshi

Classifications

• B61C13/00

  Locomotives or motor railcars characterised by their application to special systems or purposes (B61C11/00 takes precedence; self-propelled scaffold cars, break-down cranes, inspection trolleys B61D15/00; general design of track recording vehicles B61K9/00) · CPC title

• B61C11/04

  tractive effort applied to racks · CPC title

• B65G2201/0297

  Wafer cassette · CPC title

• B65G1/0457

  with suspended load carriers · CPC title

• B61C17/12 Primary

  Control gear; Arrangements for controlling locomotives from remote points in the train or when operating in multiple units (control from points outside the train B61L3/00; fluid-actuated telemotors, servomotors F15B; control devices in general G05) · CPC title