Cummins Engine Company, Inc.

Steven A Archuleta

Richard G Varo

A piston-mounted power generator has a piston-mounted magnet unit (1) formed of a coil (2) with a permanent magnet core (3) that is fitted with pole extensions (5, 6). The unit (1) is mounted to the piston skirt (8) with the pole extensions having a small clearance from the inner wall (10) of the piston cylinder formed by cylinder wall liner (12). Shallow grooves (14) are machined into the cylinder wall (10). The grooves (14) have a crescent-shaped longitudinal cross section, that extends circumferentially in the cylinder wall (10) for a distance that is only slightly longer than the width of the pole extensions. The width of each groove (14) is equal to the spacing between the pole extensions (5, 6) and the axial spacing between the adjacent pairs of grooves (14) is equal to the thickness of the pole extensions (5, 6). Electrical power is generated in the coil 2 by the rapid change in flux in the magnetic circuit linked through it as the effective gap between the poles and wall changes as the poles (5, 6) pass each of the grooves (14) and is maximized when the spacing of the poles and grooves results in the magnetic circuit being made and broken simultaneously at both poles. Transducers and telemetry modules (TTM) can be mounted within the interior of the piston and electrically connect to the coil to be powered thereby. To increase the power generated, the grooves (14') can be backfilled with a nonmagnetic material (15) by flame-spraying or the like. For special pistons, annular grooves can be used instead ones having the preferred crescent shape.

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Columbus, IN, United States of America

Steven A Archuleta