Pressure sensor

Details Pressure sensor Pressure sensor

1988-09-14

1990-06-12

Woodiel, Donald O.

Measuring and testing

Fluid pressure gauge

Diaphragm

338 4, G01L 708, G01L 906

Patent

active

049322664

DESCRIPTION:

BRIEF SUMMARY
BACKGROUND OF THE INVENTION

1. Field of the Invention
This invention relates in general to fluid pressure measuring, more specifically to an assembly including a protective separator and pressure sensitive element on support means, for transmitting pressure to the element accurately over broad manufacturing and assembly tolerances.
2. Description of the Prior Art
Sensors for detecting pressures in diesel and gasoline engines, ranging from the relatively high pressure of combustion to the lower pressure of fuel delivery pumps, generally have a measuring element which includes a pressure-sensitive element on support means, in a transmitter housing that includes a compartment which extends sealingly through an opening in the pressure vessel wall of the engine or pump system and into the pressure vessel. The support means is screwed into the compartment, with the sensitive portion of the element pressed flatly against the inner surface of the compartment at a diaphragm wall which extends into the vessel wherein the diaphragm yields to the fluid pressure.
For this purpose, however, a relatively large inner diameter of the compartment is required, which reduces the strength of the transmitter housing. In addition, the pressure responsive diaphragm of the compartment wall must be against the pressure sensitive element as flat as possible. Even the smallest tolerance differences and angle errors can lead to measurement errors because of the relatively small film thickness of the pressure-sensitive element.


SUMMARY OF THE INVENTION

The pressure sensor, according to the invention, provides accurate transmission of pressure to the pressure-sensitive element with small overall dimensioning and relatively large assembly tolerances. In addition, no thread is needed for installing the support means. Accordingly, the diameter of the compartment can be relatively small, so that the mechanical strength of the housing is improved. The mechanical fastening of the measuring element of the transmitter housing is ensured in a simple manner, e.g. by means of a weld connection to the support means which may comprise a steel rod. Since no installation thread is located on the support in the area of the pressure-sensitive element and the diaphragm within the compartment, this area is free of mechanical vibrations or deformation brought about by means of the installation of the transmitter housing in the pressure vessel wall. The pressure values transmitted by the diaphragm are accordingly not falsified by means of mechanical vibrations from the pressure vessel wall. The pressure-sensitive area of the pressure sensor is decoupled to a great extent from the twisting of the transmitter housing when it is screwed into the wall.
Conductor stripes, printed on the measuring element in a simple manner make contact with a pressure sensitive resistive film outside the area of the pressure sensor that is acted upon by pressure. The conductor strips and the resistive film can overlap. Since no feed wires are needed in the critical transmitter area and no measures for insulation are needed, a simple electrical feed line to the resistive film results.
Accordingly, there is provided a pressure sensor for detecting the pressure of a fluid confined behind a wall of a pressure vessel. The pressure sensor includes pressure sensitive means, electrically responsive to mechanical pressure, located in a compartment of a housing. The compartment, which is closed relative to the fluid, includes a diaphragm in communication with the fluid, which is moveable in response to changes in the pressure of the fluid. The pressure sensitive means is mounted in the compartment for receiving mechanical pressure exerted by movement of the diaphragm. A cap is mounted between the pressure sensitive means and the diaphragm for transmitting the mechanical pressure between them.
A support body fixedly joined with the housing, positions the pressure sensitive means so that it receives the mechanical pressure from the diaphragm. In one embodiment the support body is fixedl

REFERENCES:
patent: 3857287 (1974-12-01), Sonderegger
patent: 4483179 (1984-11-01), Oshima et al.
patent: 4570097 (1986-02-01), Shukla et al.
patent: 4735091 (1988-04-01), Engeler et al.

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