US 12,442,710 B2
Method for monitoring the function of a capacitive pressure measuring cell
Peter Kimbel, Tettnang (DE); Manfred Maurus, Bad Waldsee (DE); Fabian Kuhnhäuser, Ravensburg (DE); and Oliver Blankenhorn, Bodnegg (DE)
Assigned to IFM Electronic GmbH, Essen (DE)
Appl. No. 18/022,857
Filed by IFM Electronic GmbH, Essen (DE)
PCT Filed Jul. 23, 2021, PCT No. PCT/EP2021/070678
§ 371(c)(1), (2) Date Feb. 23, 2023,
PCT Pub. No. WO2022/042964, PCT Pub. Date Mar. 3, 2022.
Claims priority of application No. 10 2020 122 128.2 (DE), filed on Aug. 25, 2020.
Prior Publication US 2023/0314260 A1, Oct. 5, 2023
Int. Cl. G01L 27/00 (2006.01); G01L 9/00 (2006.01); G01L 9/12 (2006.01); G01L 19/00 (2006.01); G01L 19/04 (2006.01)
CPC G01L 27/007 (2013.01) [G01L 9/0072 (2013.01); G01L 19/0092 (2013.01)] 4 Claims
OG exemplary drawing
 
1. A method for monitoring a function of a capacitive pressure measuring cell (10) comprising a measuring capacitor (CM) and a reference capacitor (CR) as well as a temperature element,
wherein a pressure measurement value p is obtained by forming a quotient Q from the capacitance values of the reference capacitor (CR) and the measuring capacitor (CM),
the method comprising the following method steps:
in a matching procedure, determining and storing in a lookup table a characteristic curve of values of the quotient Q and the corresponding capacitance of the measuring capacitor (CM) versus pressures at different temperature scenarios, so as to define an expected behavior of a course in which corresponding absolute values of the quotient Q and the capacitance of the measuring capacitor (CM) are compared with each other at the different temperature scenarios;
then in an operation step, continuously assigning each of the corresponding absolute values of the quotient Q and the corresponding capacitance of the measuring capacitor (CM) from the lookup table with a pressure measurement value p at a temperature detected at a respective moment by the temperature element;
continuing with the operation step, determining a behavior of a course in which corresponding absolute values of the quotient Q and the capacitance of the measuring capacitor (CM) are compared with each other at the temperatures detected by the temperature element;
wherein:
in the case of a significant deviation of the determined behavior from the expected behavior, the evaluation unit is temporarily switched into a safety mode while a temperature gradient detected by the temperature element is evaluated; then
if there is a significant increase in the detected temperature gradient, a temperature compensation is initiated; and
if there is no significant increase in the detected temperature gradient, an error signal is generated.