Self-aligning tachometer with interchangeable elements for different resolution outputs

A tachometer for monitoring the rotation of an output shaft of a motor enclosed within a housing having a standard NEMA end plate secured to the housing via a plurality of fasteners extending through aligned mounting holes in the end plate and the housing wherein the output shaft projects from the housing, the tachometer comprising:

• a) a substantially cylindrical enclosure adapted to be secured to the end plate of the motor housing using the aligned mounting holes in the end plate and the housing, the enclosure having a radial center and a longitudinal axis which, when the enclosure is secured to the housing, are aligned with a longitudinal axis of the output shaft, said enclosure having at least one machined mounting surface in a wall portion thereof which projects radially from said enclosure;
• said mounting surface having an aperture therein open in a radial direction;
• b) a sensor module including at least one sensor, said sensor module mountable on said machined mounting surface of said enclosure such that said module protrudes through said aperture with said sensor facing radially inwardly;
• and
• c) an annular drum having at least one pattern arranged on a circumferential surface thereof capable of being sensed by said sensor, said drum enclosed within said enclosure and operatively fixed on said output shaft for rotation therewith, wherein said at least one pattern is axially aligned with said sensor and radially spaced therefrom by a predetermined radial gap in a self-aligning manner and without further adjustment when said drum is fixed to said output shaft and said enclosure is mounted on said end plate in an operatively assembled relationship, so that upon rotation of said shaft and said drum, said sensor will sense rotation of said pattern.

A tachometer for monitoring the rotation of an output shaft of a motor enclosed within a housing, wherein the output shaft projects from the housing, the tachometer comprising:

• a) an enclosure adapted to be secured to an end plate of the motor housing, the enclosure having a radial center and a longitudinal axis which, when the enclosure is secured to the housing, are aligned with a longitudinal axis of the output shaft, said enclosure having at least one mounting surface in a wall portion thereof, said mounting surface having an aperture therein open in a radial direction;
• b) a sensor module including at least one sensor, said sensor module mountable on said mounting surface of said enclosure such that said module protrudes through said aperture with said sensor facing radially inwardly;
• and
• c) an annular drum having at least one pattern arranged on a circumferential surface thereof capable of being sensed by said sensor, said drum operatively fixed on said output shaft, wherein said at least one pattern is aligned with said sensor and radially spaced therefrom by a predetermined radial gap when said drum is fixed to said output shaft and said enclosure is mounted on said end plate in an operatively assembled relationship, so that upon rotation of said shaft and said drum, said sensor will sense rotation of said pattern, and
• wherein said sensor module mounts said at least one sensor and a second sensor on a common substrate, said module including a programmable circuit connected to receive said first and second electrical signals, said programmable circuit scaling the timings of said timing signals by a scaling factor to provide scaled quadrature output signals, said programmable circuit including a scale selection circuit for setting the scale factor.

A tachometer for monitoring the rotation of an output shaft of a motor enclosed within a housing, wherein the output shaft projects from the housing, the tachometer comprising:

• a) an enclosure adapted to be secured to an end plate of the motor housing, the enclosure having a radial center and a longitudinal axis which, when the enclosure is secured to the housing, are aligned with a longitudinal axis of the output shaft, said enclosure having at least one mounting surface in a wall portion thereof, said mounting surface having an aperture therein open in a radial direction;
• b) a sensor module including at least one sensor, said sensor module mountable on said mounting surface of said enclosure such that said module protrudes through said aperture with said sensor facing radially inwardly;
• and
• c) an annular drum having at least one pattern arranged on a circumferential surface thereof capable of being sensed by said sensor, said drum operatively fixed on said output shaft, wherein said at least one pattern is aligned with said sensor and radially spaced therefrom by a predetermined radial gap when said drum is fixed to said output shaft and said enclosure is mounted on said end plate in an operatively assembled relationship, so that upon rotation of said shaft and said drum, said sensor will sense rotation of said pattern;
• and further comprising a plurality of annular drums interchangeable with said annular drum, each having at least one pattern scaled to a different pulse count, and wherein each drum has a diameter which maintains a constant pattern pitch for each different pulse count.