The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Aug. 24, 1993
Filed:
Aug. 30, 1991
William Pickering, University Heights, OH (US);
Bruce A Nielsen, Painesville, OH (US);
Caterpillar Industrial Inc., Mentor, OH (US);
Abstract
Motor control systems having direction contacts for steering current through a motor are commonly associated with electrical industrial vehicles, such as lift trucks. Advantageously, the operation of the direction contacts should be optimized in order to prevent switching the contacts when current is present to the extent that such switching can be eliminated. The instant apparatus includes a logic device for receiving speed and direction demand signals and responsively controlling the direction contacts associated with a vehicle motor. The logic device also receives signals from a current sensor responsive to the magnitude of electrical current flowing through the electric motor. In response to the motor current signal indicating a value less than a predetermined value concurrent with either the motor direction demand signal having a neutral value or the motor speed demand signal having a zero value, the logic means produces a neutral motor direction command signal. Therefore, optimal control of the motor direction contacts is attained.