Dynamoelectric machine and tachometer

Abstract

A speed sensing tachometer is built into the end bracket or end bell of a variable speed dynamoelectric machine such as a DC motor. The tachometer is completely recessed and close to the bearing supporting the shaft to occupy a minimum of longitudinal space in the machine. Multiple poles are provided on the rim of the tachometer rotor fastened to the machine shaft and these poles cooperate with first and second Hall effect switches. An electrical circuit is also provided in the same recess in the end bracket and connected to the Hall switches so that the output from the stator of the tachometer includes both a digital and an analog signal output with rotational direction sensing. Such built-in tachometer permits the DC motor to be a double shaft extension motor so that a load, fan or brake may be mounted at each end. The foregoing abstract is merely a resume of one general application, is not a complete discussion of all principles of operation or applications, and is not to be construed as a limitation on the scope of the claimed subject matter.