# US 4,393,715 A · Absolute pressure pick-up, especially for measuring pressure at intake in internal combustion engines

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- Number: US 4,393,715 A
- Document ID: US4393715A
- Status: Granted
- Kind: A
- Application number: 06/256,975
- Filed: 1981-04-23
- Granted: 1983-07-19
- Earliest claimed: 1980-05-07
- Assignees: Regie Nationale des Usines Renault
- Inventors: Claude Lombard
- Web page: https://patentgrep.com/patent/US4393715A

## CPC

- G01L 9/0036: {using variations in inductance}
- G01L: MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE (weighing G01G)

## Abstract

Disclosed is an absolute pressure pick-up for the intake in an internal combustion engine. The pick-up consists of a screened magnetic circuit equipped with a mobile core placed inside an elastic bellows. A chamber (4) that receives either the pressure to measure or the reference vacuum is around the bellows.

## Claims

### Claim 1

A pressure pick-up comprising:
a sealable rigid cylindrical envelope having two ends;
a fluid tight elastic bellows in said envelope and having one end attached to one of said ends of said envelope;
biasing means associated with said bellows for expanding said bellows;
a ferrite screened magnetic circuit in said bellows;
a mobile ferrite core in said circuit and fixed to the other end of said bellows;
a single induction coil within said circuit, said coil having two ends extending out of said envelope;
means for applying a fluid pressure in said envelope and only on the outside of said bellows; and
means for providing a fluid tight seal for said envelope at points where said two ends exit said envelope.

### Claim 2 (depends on 1)

The pick-up of claim 1 wherein said circuit, ferrite core and induction coil are all coaxial with the longitudinal axis of said envelope, and including screw means for adjusting the initial axial position of said coil relative to said circuit.

### Claim 3 (depends on 1, 2)

The pick-up of claims 1 or 2 wherein the interior of said bellows is subject to an air pressure less than atmospheric pressure.