# US 5,703,282 A · Pressure sensor for pressure detection in combustion chamber of internal combustion engine

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- Number: US 5,703,282 A
- Document ID: US5703282A
- Status: Granted
- Kind: A
- Application number: 08/734,240
- Filed: 1996-10-16
- Granted: 1997-12-30
- Earliest claimed: 1995-10-19
- Assignees: Robert Bosch GmbH
- Inventors: Matthias Kuesell; Andreas Duell; Karl Bender; Kay Borchert
- Web page: https://patentgrep.com/patent/US5703282A

## CPC

- G01L 23/08: operated electrically {(G01L23/22 takes precedence)}
- G01L 23/18: by resistance strain gauges
- G01L: MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE (weighing G01G)

## Abstract

A pressure sensor for pressure detection in a combustion chamber of internal combustion engines of motor vehicles has a housing provided with an opening, a measuring element, a plunger arranged in the opening of the housing and having one end acting on the measuring element so that a measuring signal is produced proportionally to a pressure to be determined, the plunger directly abutting against the measuring element and having a material with a yielding point which is smaller than a breaking limit of a material of the measuring element, the end of the plunger which acts on the measuring element is spherical and abuts against the measuring element with such a contact surface that occurring stresses do not exceed a predetermined nominal value.

## Claims

### Claim 1

A pressure sensor for pressure detection in a combustion chamber of internal combustion engines of motor vehicles, comprising a housing provided with an opening; a measuring element; a plunger arranged in said opening of said housing and having one end acting on said measuring element so that a measuring signal is produced proportionally to a pressure to be determined, said plunger directly abutting against said measuring element and having a material with a yielding point which is smaller than a breaking limit of a material of said measuring element, said end of said plunger which acts on said measuring element being spherical and directly abutting against said measuring element with such a contact surface that occurring stresses do not exceed a predetermined nominal value.

### Claim 2 (depends on 1)

A pressure sensor as defined in claim 1, wherein a difference of a roughness of a surface of said end of said plunger and a roughness of a surface of said measuring element is not greater than two micrometers.

### Claim 3 (depends on 1)

A pressure sensor as defined in claim 1, wherein a difference of a roughness of a surface of said one end of said plunger and a roughness of a surface of said measuring element is not greater than one micrometer.

### Claim 4 (depends on 1)

A pressure sensor as defined in claim 1, wherein said measuring element is a silicon chip in which resistors connected in a Wheatstone bridge are arranged.

### Claim 5 (depends on 4)

A pressure sensor as defined in claim 4, wherein said resistors are piezo-resistive resistors.

### Claim 6 (depends on 1)

A pressure sensor as defined in claim 1, wherein said plunger and said opening of said housing are formed so that said plunger is guided in said opening of said housing.

### Claim 7 (depends on 1)

A pressure sensor as defined in claim 1, wherein said opening has an end which is closed with a diaphgram, said plunger having another ending abutting against said diaphragm.

### Claim 8 (depends on 1)

A pressure sensor as defined in claim 1, wherein said plunger abut against said measuring element in a contact region which does not have a passivating layer covering the resistors.

### Claim 9 (depends on 1)

A pressure sensor as defined in claim 1, wherein said measuring element and said plunger have surfaces which are spaced from one another so as to form a gap; and further comprising a gel-like mass located in said gap.

### Claim 10 (depends on 9)

A pressure sensor as defined in claim 9; and further comprising a passivating layer arranged on a surface of said measuring element, said gel-like mass being located on said passivating layer.