US 4,110,676 AGranted

Dynamoelectric machine and tachometer

AssigneeReliance Electric Company

InventorsJohn D. Edick, Kenneth A. Ostrander

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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.

Claims13

Dependent claims

A combined dynamoelectric machine and tachometer enclosed within a single frame, comprising in combination,

an end bracket forming a part of said frame and surrounding a rotatable shaft of the machine,
wall means defining recess means in said end bracket,
a tachometer rotor mounted within said recess means and connected to be rotated in accordance with rotation of said shaft of the machine,
said tachometer rotor having a plurality of magnetic poles,
magnetically responsive first and second transducer means having an electrical output,
means mounting both said transducer means in said recess means close to said magnetic poles of said rotor to be magnetically actuated by rotation of said tachometer rotor,
means including said rotor and both said transducer means to sense direction as well as rotational speed of said tachometer rotor,
said second transducer means being mounted in a position spaced from said first transducer means by a distance p(n + 1/2), where n is any integer and p is the pole pitch between adjacent north and south poles,
said direction sensing means including a D flip-flop,
one transducer means being connected to the clock input of said flip-flop and the other transducer means being connected to the data input of said flip-flop,
and amplifier means connected to the Q and Q outputs of said flip-flop to establish a negative or a positive output from said amplifier in accordance with first and second directions of rotation of the machine, respectively.

8 more elements

Dependencies are inferred from the claim text.