Crane

Patent metadata

Field	Value
Publication number	US-2016257534-A1
Application number	US-201615055721-A
Country	US
Kind code	A1
Filing date	Feb 29, 2016
Priority date	Mar 2, 2015
Publication date	Sep 8, 2016
Grant date	—

Abstract

A crane includes an overload safety device and a identifying unit. The overload safety device includes a maximum-load calculating unit configured to calculate a maximum load that a winch drum is capable of winding up with driving torques output from the remaining electric motors other than a failed electric motor identified by the identifying unit, an updating unit configured to update a set hoisting ability value stored in a storing unit to a value equal to the maximum load, and a control unit configured to cause the remaining electric motors to operate when a value of a load derived by a load deriving unit is equal to or smaller than a latest set hoisting ability value stored in the storing unit and stop the operation of the plurality of electric motors when the value of the load derived by the load deriving unit exceeds the latest set hoisting ability value.

First claim

1 . A crane which performs winding-up and winding-down of a target object, the crane comprising:
a winch drum configured to rotate for the winding-up and the winding-down of the target object; a plurality of electric motors configured to be operated by supply of electric power to output respective driving torques for rotating the winch drum; a load deriving unit configured to derive a value of a load of the target object, the load being a load applied to the winch drum; an overload safety device configured to monitor the value of the load derived by the load deriving unit and stop an operation of each of the plurality of electric motors when the value of the load exceeds a set hoisting ability value of the crane to stop the rotation of the winch drum; and an identifying unit configured to identify a failed electric motor among the plurality of electric motors, wherein the overload safety device includes:
a storing unit configured to store the set hoisting ability value;
a maximum-load calculating unit configured to calculate a maximum load which the winch drum is capable of winding up with the driving torques output from the remaining electric motors other than the failed electric motor identified by the identifying unit;
an updating unit configured to update the set hoisting ability value stored in the storing unit to a value equal to the maximum load calculated by the maximum-load calculating unit; and
a control unit configured to perform control of the plurality of electric motors, and
the control unit performs control for stopping the operation of the failed electric motor identified by the identifying unit, causing the remaining electric motors to operate when the value of the load derived by the load deriving unit is equal to or smaller than a latest set hoisting ability value stored in the storing unit, and stopping the operation of the plurality of electric motors when the value of the load derived by the load deriving unit exceeds the latest set hoisting ability value.

2 . The crane according to claim 1 , further comprising an informing unit configured to inform an operator of the crane that the set hoisting ability value is updated, in response to the update, by the updating unit, of the set hoisting ability value stored in the storing unit.

3 . The crane according to claim 2 , wherein the informing unit is a display device which displays the set hoisting ability value after the update.

4 . The crane according to claim 1 , further comprising:
a permission input unit for receiving an input of an instruction for permitting the update of the set hoisting ability value; and an update permitting unit configured to grant permission for the update of the set hoisting ability value to the updating unit in response to the input of the instruction to the permission input unit, wherein the updating unit updates the set hoisting ability value in response to the identifying of the failed electric motor by the identifying unit and the granting of the permission for the update from the update permitting unit.

Assignees

• Kobe Steel Ltd
• Kobelco Cranes Co Ltd

Inventors

• Kawai Hiroaki
• Hiekata Takashi
• Inoue Koji
• Sasai Shintaro
• Yamashita Toshiro
• Shimomura Koichi
• Ogawa Tetsuya

Classifications

• B66C23/905

  electrical · CPC title

• B66C13/50 Primary

  Applications of limit circuits or of limit-switch arrangements (for winding mechanisms B66D1/56) · CPC title

• B66C13/22

  for electric drives (transmitting control pulses B66C13/40; systems or devices of general application H02P) · CPC title

• B66C15/00

  Safety gear (for rope, cable, or chain winding mechanisms B66D1/54) · CPC title