Bridge crane electric motor control system

• US 5,350,076 A
• Filed: 03/16/1992
• Issued: 09/27/1994
• Est. Priority Date: 01/29/1990
• Status: Expired due to Fees

• Current Assignee: Whiting Corporation (Design Marketing Concepts, Inc.)
• Original Assignee: Whiting Corporation (Design Marketing Concepts, Inc.)
• Inventors: Kalan, Brian A.
• Primary Examiner(s): Huppert, Michael S.
• Assistant Examiner(s): JOHNSON, RAYMOND B
• Application Number:
  US07/851,631
• Time in Patent Office: 925 Days
• Field of Search: 212/149-155, 212/159, 212/205, 212/209, 212/210, 212/214, 212/216, 212/217, 212/270, 414/496, 414/786, 364/183-184, 364/551.01, 364/424.04, 340/434, 340/685, 901/16
• US Class Current: 212/315
• CPC Class Codes: B66C 13/22 for electric drives transmitting control pulses B66C13/40; systems or devices of general application H02P
• CPC Class Codes: B66C 13/48 Automatic control of crane drives for producing a single or repeated working cycle; Programme control
• CPC Class Codes: B66C 15/00 Safety gear for rope, cable, or chain winding mechanisms B66D1/54
• CPC Class Codes: B66C 17/00 Overhead travelling cranes comprising one or more substantially horizontal girders the ends of which are directly supported by wheels or rollers running on tracks carried by spaced supports
• CPC Class Codes: G07C 3/00 Registering or indicating the condition or the working of machines or other apparatus, other than vehicles

Abstract

An improved bridge crane electric motor control system is disclosed, wherein a computer, a programmable controller, is employed to not only control the application of electrical energy to the motors of a bridge crane but also to count and store the instances of overload and of use. The controller is operated in accordance with a computer program which is disclosed and information relating to use is accessible by maintenance workers who may read out the amount of use and abuse of the crane and its motors and take corrective steps. The system provides greater security against unauthorized modification in the field by the operators and employs fewer and more reliable parts than previous such systems.

Claims

1. The method of operating an overhead crane of the type wherein operating units are driven in three different directions so as to position a hoist unit at any desired position within a volume of space for lifting, moving and depositing loads from one position to another within that volume, said overhead crane having three operating units including a bridge movable forwardly and reverse and a trolley movable forwardly and reverse on said bridge, a hoist mechanism mounted on said trolley for up and down movements, each of said three operating units being each independently driven by one of three separate electric motor means, each of which separate motor means is controlled by separate motor control means, said crane also including a source of command signals for operating the crane, said command signals include at least a bridge forward signal, a bridge reverse signal, a trolley forward and a trolley reverse signal, said crane also including a source of bridge overload signals and a source of trolley overload signals;

a single computer of the programmable controller type coupled to each of said three electric motor control means to selectively energize or not energize the three separate electric motors means in response to a predetermined computer program and the command signals, said computer including means for receiving said command signals as inputs, and further including means with at least an incremental bridge overload counter and an incremental trolley overload counter, for storing information as to the number of overload operations of each of said separate electric motor means for said bridge and said trolley and for outputting said information on command, said computer program including at least the following subroutines;

(a) if said bridge forward signal is present, ask if a bridge overload signal in present, if "yes", increase the bridge overload counter and take no action toward further energizing said motor means associated with said bridge, if "no", query if said bridge reverse command signal is present and if the answer to this query in "yes", take no action toward further energizing said motor means associated with said bridge, if "no", energize said electric motor means associated with said bridge to drive said bridge forward;

(b) if said trolley forward signal is present ask if a trolley overload signal is present, if "yes", increase the trolley overload counter and take no action toward further energizing said motor means associated with said trolley, if "no", query if said trolley reverse command signal is present and if the answer to this query is "yes", take no action toward further energizing said motor means associated with said trolley, if "no", energize said electric motor means associated with said trolley to drive said trolley forward;

said means for storing and outputting information stores information generated from said subroutines relative to the use of said crane over a period of time and outputs such information on command;

comprising the steps of;

(a) in response to a specific command to run a first of said three electric motor means in a selected direction, recording the selected direction of motion of said first motor means, sensing if the overload condition for that motor means is present and developing signals indicative of an overload situation in said first of said electric motor means;

(b) in response to a specific command to run a second of said three electric motor means in a selected direction, recording the selected direction of motion of said second motor means, sensing if the overload condition for that motor means is present and developing signals indicative of an overload situation in said electric motor means;

(c) recording said signals indicative of an overload situation in each of said first and second motor means as they occur over time in said programmable controller such that the number of overload situations over time as to each of the said first and said second electric motor means can be accumulated and determined by accessing said recorded information in said programmable controller;

(d) reading out the accumulated information so stored.