BRUSHLESS DC-TACHOMETER

• US 3,848,157 A
• Filed: 10/11/1972
• Issued: 11/12/1974
• Est. Priority Date: 10/11/1972
• Status: Expired due to Term

• Current Assignee: Deceased Kripl
• Original Assignee: Deceased Kripl
• Inventors: Kripl, deceased
• Primary Examiner(s): Hix, L. T.
• Application Number:
  US05/296,735
• Time in Patent Office: 762 Days
• Field of Search: 310/171 340/271 317/5
• US Class Current: 361/239
• CPC Class Codes: G01P 13/045 with speed indication
• CPC Class Codes: G01P 3/4802 by using electronic circuits in general
• CPC Class Codes: G01P 3/49 using eddy currents
• CPC Class Codes: H01F 29/12 having movable coil, winding, or part thereof; having movable shield

Abstract

A brushless dc tachometer system includes a first coil driven by a high frequency oscillator, a second coil which senses change in magnetic field, a non-magnetic rotatable disk element mounted on a shaft concentric with the first and second coils to provide a means for coupling magnetic fields and a detecting system including logic circuits coupled to the output of the second coil for producing an ultimate output signal proportional to the speed and direction of rotation of the input shaft.

Claims

1. A device for sensing the rotational direction and speed of a rotatable member comprising a signal generator having a non-magnetic conductive rotor attached for rotation by said rotatable member;

a pair of input windings proximate said rotor;

a pair of output sense windings in quadrature with said input windings proximate said conductive rotor, said output sense windings being electromagnetically coupled to said input windings solely through said rotor, said output sense windings providing a pair of alternating output signals during rotation of said rotatable member having a phase relation and amplitude dependent on the direction and speed of rotation of said rotor;

energizing means connected to said input windings for applying an alternating energizing current of predetermined frequency and amplitude to said input windings; and

circuit means synchronized by said energizing means for converting said pair of alternating output signals from said output windings to a single unidirectional signal having a polarity and amplitude related to the direction and speed of said rotor.

2. A device for sensing the rotational direction and speed of a rotatable member in accordance with claim 1 in which said energizing means is a drive oscillator connected to said input windings, and said circuit means comprises a pair of gate circuits connected to receive said output signals separately from said output windings said gate circuits being connected to said oscillator for synchronously gating predetermined portions of said alternating output signals, and summing circuit means connected to the outPuts of said gating circuits for summing the gated portions of said output signals said summing circuit producing a unidirectional signal of an amplitude and polarity related to the speed and direction of rotation of said rotor.

3. A device for sensing the rotational direction and speed of a rotatable member in accordance with claim 2 in which said synchronizing signal from said drive oscillator enables one gate circuit to gate odd half cycles of the output signal from one output winding, and enables the second gate circuit to gate even half cycles of the output signal from said second output winding.