Pulse generator for variable-speed drives

Claim 1

A pulse generator for variable speed drives, particularly sewing machine drives having a main rotatable shaft and a housing, comprising: a casing defining an inner space; a generator shaft rotatably mounted in said casing and rotatable in synchronism with the main shaft of the sewing machine drive; a pulse disc having light-dark zones connected to said generator shaft in said inner space; a light transmitting module and a light-receiving module in said casing disposed on either side of at least a portion of said pulse disc; said casing including on either side of said pulse disc and spaced from said pulse disc, bearing surfaces bearing against corresponding bearing surfaces of said generator shaft for centering and rotatably mounting said pulse disc in said inner space of said casing, said bearing surfaces including axially extending and radially extending surfaces relative the axis of the said generator shaft to axially and radially hold the position of said casing with respect to said generator shaft; said casing comprising two casing parts each having one receiving chamber for radially receiving one of said light-transmitting and light-receiving modules respectively; each of said casing parts including a radial wall separating said receiving chamber from said inner space with a plurality of axially extending parallel apertures extending through each wall between each of said receiving chambers and said inner space for the passage of light between said light-transmitting module and said light-receiving module and through portions of said pulse disc; each of said light-transmitting and light-receiving modules including a circuit board, each of said receiving chambers comprising a slide-in compartment for radially receiving each of said circuit boards respectively; and each of said receiving chambers of each casing parts being closed when said casing parts are assembled to form said casing by a cover plate extending from the other of said casing parts.