Multilevel pressure sensor

Patent metadata

Field	Value
Publication number	US-9989431-B2
Application number	US-201415103107-A
Country	US
Kind code	B2
Filing date	Nov 14, 2014
Priority date	Dec 11, 2013
Publication date	Jun 5, 2018
Grant date	Jun 5, 2018

Abstract

A pressure sensor comprises a deformable measuring diaphragm, and a mating body connected in a pressure-tight manner and forms a measuring chamber in which a reference pressure is present. A pressure can be applied to an outside of the measuring diaphragm. The pressure sensor has a capacitive transducer having at least one mating body electrode and at least one diaphragm electrode. Above a pressure limit value for the pressure, at least one central surface section of the measuring diaphragm rests against the mating body with a contact surface area, the size of which is dependent on the pressure. The pressure sensor also has a resistive transducer for converting a pressure-dependent deformation of the measuring diaphragm, when pressed in a range of values above the pressure limit value, into an electrical signal using an electrical resistance which is dependent on the contact surface area of the measuring diaphragm on the mating body.

First claim

The invention claimed is:

1. A pressure sensor, comprising:
a measuring diaphragm;
a mating body, said measuring diaphragm is in pressure-tight connection with said mating body along a circumferential edge;
a measuring chamber formed between said mating body and said pressure diaphragm in which a reference value is applied;
a capacitive transducer with at least one mating body electrode and at least one diaphragm electrode; and
a resistive transducer, wherein:
a pressure to be measured is applied to the outside of said measuring diaphragm facing away from said measuring chamber;
said measuring diaphragm is deformable on the basis of the pressure;
the capacity between said at least one mating body electrode and said at least one diaphragm electrode depends on the pressure-dependent deformation of said measuring diaphragm;
at least a central surface section of said measuring diaphragm rests on said mating body with a resting surface area whose size depends on the pressure above a pressure limit value for the pressure; and
said resistive transducer converts a pressure-dependent deformation of said measuring diaphragm at pressures in a value range above a pressure limit value into an electrical signal based on an electrical resistance that is dependent on said resting surface area of said measuring diaphragm on said mating body.

2. The pressure sensor according to claim 1 , wherein:
said resistive transducer has at least two electrodes, with the electrical resistor on the basis of which said resistive transducer provides the electrical signal must be determined between the at least two electrodes.

3. The pressure sensor according to claim 2 , wherein:
said resistive transducer has at least one resistor layer in which at least one of said electrodes of said resistive transducer is coated;
the resistor layer of a first electrode of said resistive transducer has a contact surface area to a second electrode and/or to a resistor layer of said second electrode depending on the resting surface area of said measuring diaphragm on said mating body at pressures above the pressure limit value.

4. The pressure sensor according to claim 3 , wherein:
the contact surface area being essentially equal to the resting surface area.

5. The pressure sensor according to claim 3 , wherein:
said resistance layer comprises SiC or TiO2.

6. The pressure sensor according to claim 2 , wherein:
said diaphragm electrode of said capacitive transducer forms a first electrode of said resistive transducer; and
said at least one mating body electrode of said capacitive transducer forms a second electrode of the resistive transducer.

7. The pressure sensor according to claim 1 , wherein:
said capacitive transducer comprises at least two mating body electrodes, with the first of the mating body electrodes being arranged in a first radial area, and the second of the mating body electrodes being arranged in a second radial area, with the first radial area comprising smaller radii than the second radial area, with the resting surface area being formed only in the first radial area for a first pressure range above the pressure limit value, with the resistive transducer being designed to provide a signal that depends on the resistance between said first mating body electrode and said diaphragm electrode.

8. The pressure sensor according to claim 7 , wherein:
said evaluation circuit is designed to determine a pressure measuring value dependent on a capacity between a diaphragm electrode and the second mating body electrode in at least a partial section of said first pressure range that directly follows the pressure limit value.

9. The pressure sensor according to claim 1 , furthermore comprising:
an evaluation circuit that is designed to provide a pressure measuring value dependent on the capacity for pressures below the pressure limit value, with the signal of said resistive transducer becoming part of the determination of the pressure measuring value above the pressure limit value.

10. The pressure sensor according to claim 9 , wherein:
said evaluation circuit is designed to determine a pressure measuring value depending on the signal from said resistive transducer when the resistance falls below a resistance limit value.

11. The pressure sensor according to claim 1 , wherein:
said measuring diaphragm and said mating body include a ceramic material—in particular, corundum—with the electrodes of the capacitive transducer comprising metal.

12. The pressure sensor according to claim 1 , wherein:
said measuring diaphragm comprises a semiconductor—in particular, silicon.

Assignees

• Endress Hauser Gmbh Co Kg

Inventors

• Rossberg Andreas
• Textor Olaf
• Wosnitza Elmar

Classifications

• G01L9/0072 Primary

  using variations in capacitance · CPC title

• G01L9/0051

  using variations in ohmic resistance · CPC title