# US 9,518,888 B2 · Method for ascertaining an offset of an output signal of an evaluation circuit integrated in a sensor, preferably of a pressure sensor installed in a combustion chamber of an internal combustion engine, and sensor > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 9,518,888 B2 - Document ID: US9518888B2 - Status: Granted - Kind: B2 - Application number: 14/397,905 - Filed: 2013-04-26 - Published: 2015-05-21 - Granted: 2016-12-13 - Earliest claimed: 2012-05-02 - Assignees: Robert Bosch GmbH - Applicants: Robert Bosch GmbH - Inventors: Harald Ryll - Web page: https://patentgrep.com/patent/US9518888B2 ## CPC - G01L 27/002: {Calibrating, i.e. establishing true relation between transducer output value and value to be measured, zeroing, linearising or span error determination} - F02B 77/085: {with sensors measuring combustion processes, e.g. knocking, pressure, ionization, combustion flame} - F02D 35/023: {by determining the cylinder pressure} - F02D 41/28: Interface circuits - F02P 19/028: {the glow plug being combined with or used as a sensor} - G01L 23/22: for detecting or indicating knocks in internal-combustion engines; Units comprising pressure-sensitive members combined with ignitors for firing internal-combustion engines - G01L 23/222: {using piezoelectric devices} - G01M 15/08: by monitoring pressure in cylinders - F02D 2041/281: {between sensors and control unit} - F02D 2041/285: {the sensor having a signal processing unit external to the engine control unit} - G01L: MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE (weighing G01G) - F02B: INTERNAL-COMBUSTION PISTON ENGINES; COMBUSTION ENGINES IN GENERAL (gas-turbine plants F02C; hot-gas or combustion-product positive-displacement engine plants F02G) - F02D: CONTROLLING COMBUSTION ENGINES (vehicle fittings, acting on a single sub-unit only, for automatically controlling vehicle speed B60K31/00; conjoint control of vehicle sub-units of different type or different function, road vehicle drive control systems for purposes other than the control of a single sub-unit B60W) - F02P: IGNITION, OTHER THAN COMPRESSION IGNITION, FOR INTERNAL-COMBUSTION ENGINES; TESTING OF IGNITION TIMING IN COMPRESSION-IGNITION ENGINES ({anti-pollution means for internal-combustion engines F02B17/00}; specially adapted for rotary-piston or oscillating-piston engines F02B53/12; {ignition of gas turbine plants F02C7/26; ignition of jet propulsion plants F02K9/95; starting of combustion engines F02N9/00}; ignition of combustion apparatus in general, glowing plugs F23Q; measuring of physical variables in general G01; controlling in general G05; data processing in general G06; electrical components in general see Section H; {ignition coils H01F38/12}; sparking plugs H01T13/00) - G01M: TESTING STATIC OR DYNAMIC BALANCE OF MACHINES OR STRUCTURES; TESTING OF STRUCTURES OR APPARATUS, NOT OTHERWISE PROVIDED FOR ## Abstract In a method for ascertaining an offset of an output signal of an evaluation circuit integrated in a sensor, the output signal is supplied to a control unit which analyzes the output signal, and a reset of the evaluation circuit for the adjustment of the output signal to a base level is performed prior to each measuring operation of the sensor, and the control unit ascertains the offset of the output signal of the evaluation circuit upon an occurrence of a start signal output by the evaluation circuit. ## Claims ### Claim 1 A method for ascertaining an offset of an output signal of an evaluation circuit integrated in a combustion chamber pressure sensor, the combustion chamber pressure sensor projecting into a combustion chamber of an internal combustion engine, comprising: prior to each measuring operation of the sensor, resetting the evaluation circuit for adjusting the output signal to a base level; forwarding the output signal of the evaluation circuit to a control unit which analyzes the output signal; ascertaining by the control unit an offset of the output signal of the evaluation circuit upon an occurrence of a start signal output by the evaluation circuit; and correcting the output signal of the evaluation circuit using the calculated offset. ### Claim 2 (depends on 1) The method as recited in claim 1, wherein the start signal consists of an application of a predefined level of the output signal of the evaluation circuit. ### Claim 3 (depends on 2) The method as recited in claim 2, wherein the predefined level of the output signal corresponds to a level of a grounded connection of the evaluation circuit. ### Claim 4 (depends on 2) The method as recited in claim 2, wherein the control unit, after receiving the start signal, carries out the calculation of the offset within a predefined time period starting immediately after the receipt of the start signal. ### Claim 5 (depends on 4) The method as recited in claim 4, wherein the predefined time period is selected in such a way that a diagnosis of the output signal of the evaluation circuit running in the control unit is not detected. ### Claim 6 (depends on 4) The method as recited in claim 4, wherein the start signal is triggered by an internal reset of the evaluation circuit. ### Claim 7 A combustion chamber pressure sensor system projecting into a combustion chamber of an internal combustion engine, comprising: an evaluation circuit which transmits an output signal to a control unit which analyzes the output signal, wherein the evaluation circuit performs, prior to each measuring operation of the sensor, an internal reset for adjusting the output signal to a base level; and a start signal unit which outputs to the control unit a start signal for ascertaining an offset of the output signal of the evaluation circuit. ### Claim 8 (depends on 7) The system as recited in claim 7, wherein the start signal unit includes a switching circuit logic which applies the start signal to an output of the evaluation circuit. ### Claim 9 (depends on 8) The system as recited in claim 8, wherein the switching circuit logic is a transistor. ### Claim 10 (depends on 9) The system as recited in claim 9, wherein a flip-flop circuit for adjusting a predefined time period for the offset determination is connected upstream from the switching circuit logic. ### Claim 11 A control unit for ascertaining an offset of an output signal of an evaluation circuit integrated in a combustion chamber pressure sensor, the combustion chamber pressure sensor projecting into a combustion chamber of an internal combustion engine, comprising: a calculation unit including a processor configured to: ascertain an offset of the output signal of the evaluation circuit upon an occurrence of a start signal output by the evaluation circuit; and correct the output signal of the evaluation circuit using the calculated offset and supply the corrected output signal for a further evaluation. ### Claim 12 (depends on 11) The control unit as recited in claim 11, wherein the calculation unit ascertains the offset within a time period which is predefined by a duration of the occurrence of the start signal.