# US 5,703,483 A · Pulse tachometer with sender connected to inductive proximity sensor

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- Number: US 5,703,483 A
- Document ID: US5703483A
- Status: Granted
- Kind: A
- Application number: 08/521,983
- Filed: 1995-08-31
- Granted: 1997-12-30
- Earliest claimed: 1994-09-01
- Assignees: Electricite de France (Service National)
- Inventors: Patrick Bernard; Jean-Pierre Atton
- Web page: https://patentgrep.com/patent/US5703483A

## CPC

- G01P 3/49: using eddy currents
- G01P 3/486: delivered by photo-electric detectors
- G01P: MEASURING LINEAR OR ANGULAR SPEED, ACCELERATION, DECELERATION, OR SHOCK; INDICATING PRESENCE, ABSENCE, OR DIRECTION, OF MOVEMENT (measuring or recording blood flow A61B5/02, A61B8/06; monitoring speed or deceleration of electrically-propelled vehicles B60L3/00; vehicle lighting systems adapted to indicate speed B60Q1/54; determining position or course in navigation, measuring ground distance in geodesy or surveying G01C; combined measuring devices for measuring two or more variables of movement G01C23/00; measuring velocity of sound G01H; measuring velocity of light G01J7/00; measuring direction or velocity of solid objects by reception or emission of radiowaves or other waves and based on propagation effects, e.g. Doppler effect, propagation time, direction of propagation, G01S; measuring speed of nuclear radiation G01T; measuring acceleration of gravity G01V; {measuring or recording the speed of trains B61L23/00; speed indicators incorporated in motor vehicles B60K35/00; measuring frequency or phase G01R; traffic control G08G})

## Abstract

The pulse tachometer for measuring the rotation of a rotating element (A) is characterized in that it comprises an inductive proximity sensor (10) placed in the vicinity of this element (A) in order to generate an electric pulse (100) upon each revolution of the element (A), a sender (20) connected to this sensor (10) for receive this electric pulse (100), shaping it and converting it into an optical signal, an optical-fibre link (30) connected to this sender (20) and to a receiver (40) for receiving this optical signal from the sender (20) and routing it to this receiver (40) in order to use it so as to calculate the speed of the rotating element. Application to rotating machines, for example turbine generators.

## Claims

### Claim 1

Pulse tachometer for measuring the rotation of a rotating element (A), comprising an inductive proximity sensor (10) placed in the vicinity of this element (A) in order to generate an electric pulse (100) upon each revolution of the element (A), characterized in that it comprises a sender (20) connected to this sensor (10) in order to receive this electric pulse (100), shape it and convert it into an optical signal, and an optical-fibre link (30) connected to this sender (20) and to a receiver (40) for receiving this optical signal from the sender (2)) and routing it to this receiver (40) in order to use it so as to calculate the speed of the rotating element, the said sender (20) comprising a shaping circuit (21) for stretching the duration of the electric pulse (100), and a converter (22) for converting the stretched electric pulse into an optical signal.

### Claim 2 (depends on 1)

The tachometer according to claim 1, characterized in that the shaping circuit (21) comprises an operational amplifier (211), a diode (212) connected to one input of said operational amplifier, and a programmable changeover switch connected to an output of said amplifier, another input of said operational amplifier (211) being grounded.

### Claim 3 (depends on 2)

Tachometer according to claim 2, characterized in that the programmable changeover switch (213) comprises an electronic switch (2131) and a drive circuit (2132) controlling it.

### Claim 4 (depends on 3)

Tachometer according to claim 3, characterized in that the sender (20) comprises an auxiliary circuit (23) for monitoring the occurrence of the electric pulses (100).

### Claim 5 (depends on 1)

The tachometer as set forth in claim 1, wherein said rotating element comprises a turbine generator shaft.

### Claim 6 (depends on 2)

Tachometer according to claim 2, characterized in that the sender (20) comprises an auxiliary circuit (23) for monitoring the occurrence of the electric pulses (100).

### Claim 7 (depends on 1)

Tachometer according to claim 1, characterized in that the sender (20) comprises an auxiliary circuit (23) for monitoring the occurrence of the electric pulses (100).