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:
Sep. 20, 1988
Filed:
May. 21, 1987
William Pickering, University Heights, OH (US);
Wayne T Wiblin, Ashtabula, OH (US);
Caterpillar Industrial Inc., Mentor, OH (US);
Abstract
An apparatus for controlling the supply of power to an electric drive motor normally controls the duty cycle of a power switching element to produce a variety of vehicle speeds. The apparatus typically controls the rate of change of the duty cycle to provide smooth vehicle operation. During periods of extended high speed, high load operation the apparatus bypasses the power switching element and connects the vehicle battery directly to the drive motor via a contactor. Under normal operating conditions the bypass contactor is energized after a relatively short preselected delay; however, where the vehicle is heavily loaded, such that current limiting of the power switching element exists, the apparatus interactively delays energization of the bypass contactor to allow the vehicle sufficient time to accelerate to a higher speed. Such a control system advantageously reduces drive line shock and jerky operation of the vehicle, as well as, excessive sparking at the contactor.