EP2844971A1 - Method for determining 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 a sensor - Google Patents

Method for determining 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 a sensor

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Publication number
EP2844971A1
EP2844971A1 EP13718848.8A EP13718848A EP2844971A1 EP 2844971 A1 EP2844971 A1 EP 2844971A1 EP 13718848 A EP13718848 A EP 13718848A EP 2844971 A1 EP2844971 A1 EP 2844971A1
Authority
EP
European Patent Office
Prior art keywords
output signal
evaluation circuit
offset
sensor
combustion chamber
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP13718848.8A
Other languages
German (de)
French (fr)
Inventor
Harald Ryll
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Robert Bosch GmbH
Original Assignee
Robert Bosch GmbH
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Robert Bosch GmbH filed Critical Robert Bosch GmbH
Publication of EP2844971A1 publication Critical patent/EP2844971A1/en
Withdrawn legal-status Critical Current

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Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
    • G01L27/00—Testing or calibrating of apparatus for measuring fluid pressure
    • G01L27/002—Calibrating, i.e. establishing true relation between transducer output value and value to be measured, zeroing, linearising or span error determination
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02D—CONTROLLING COMBUSTION ENGINES
    • F02D41/00—Electrical control of supply of combustible mixture or its constituents
    • F02D41/24—Electrical control of supply of combustible mixture or its constituents characterised by the use of digital means
    • F02D41/26—Electrical control of supply of combustible mixture or its constituents characterised by the use of digital means using computer, e.g. microprocessor
    • F02D41/28—Interface circuits
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02B—INTERNAL-COMBUSTION PISTON ENGINES; COMBUSTION ENGINES IN GENERAL
    • F02B77/00—Component parts, details or accessories, not otherwise provided for
    • F02B77/08—Safety, indicating, or supervising devices
    • F02B77/085—Safety, indicating, or supervising devices with sensors measuring combustion processes, e.g. knocking, pressure, ionization, combustion flame
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02D—CONTROLLING COMBUSTION ENGINES
    • F02D35/00—Controlling engines, dependent on conditions exterior or interior to engines, not otherwise provided for
    • F02D35/02—Controlling engines, dependent on conditions exterior or interior to engines, not otherwise provided for on interior conditions
    • F02D35/023—Controlling engines, dependent on conditions exterior or interior to engines, not otherwise provided for on interior conditions by determining the cylinder pressure
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02P—IGNITION, OTHER THAN COMPRESSION IGNITION, FOR INTERNAL-COMBUSTION ENGINES; TESTING OF IGNITION TIMING IN COMPRESSION-IGNITION ENGINES
    • F02P19/00—Incandescent ignition, e.g. during starting of internal combustion engines; Combination of incandescent and spark ignition
    • F02P19/02—Incandescent ignition, e.g. during starting of internal combustion engines; Combination of incandescent and spark ignition electric, e.g. layout of circuits of apparatus having glowing plugs
    • F02P19/028—Incandescent ignition, e.g. during starting of internal combustion engines; Combination of incandescent and spark ignition electric, e.g. layout of circuits of apparatus having glowing plugs the glow plug being combined with or used as a sensor
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
    • G01L23/00—Devices or apparatus for measuring or indicating or recording rapid changes, such as oscillations, in the pressure of steam, gas, or liquid; Indicators for determining work or energy of steam, internal-combustion, or other fluid-pressure engines from the condition of the working fluid
    • G01L23/22—Devices or apparatus for measuring or indicating or recording rapid changes, such as oscillations, in the pressure of steam, gas, or liquid; Indicators for determining work or energy of steam, internal-combustion, or other fluid-pressure engines from the condition of the working fluid for detecting or indicating knocks in internal-combustion engines; Units comprising pressure-sensitive members combined with ignitors for firing internal-combustion engines
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
    • G01L23/00—Devices or apparatus for measuring or indicating or recording rapid changes, such as oscillations, in the pressure of steam, gas, or liquid; Indicators for determining work or energy of steam, internal-combustion, or other fluid-pressure engines from the condition of the working fluid
    • G01L23/22—Devices or apparatus for measuring or indicating or recording rapid changes, such as oscillations, in the pressure of steam, gas, or liquid; Indicators for determining work or energy of steam, internal-combustion, or other fluid-pressure engines from the condition of the working fluid for detecting or indicating knocks in internal-combustion engines; Units comprising pressure-sensitive members combined with ignitors for firing internal-combustion engines
    • G01L23/221—Devices or apparatus for measuring or indicating or recording rapid changes, such as oscillations, in the pressure of steam, gas, or liquid; Indicators for determining work or energy of steam, internal-combustion, or other fluid-pressure engines from the condition of the working fluid for detecting or indicating knocks in internal-combustion engines; Units comprising pressure-sensitive members combined with ignitors for firing internal-combustion engines for detecting or indicating knocks in internal combustion engines
    • G01L23/222—Devices or apparatus for measuring or indicating or recording rapid changes, such as oscillations, in the pressure of steam, gas, or liquid; Indicators for determining work or energy of steam, internal-combustion, or other fluid-pressure engines from the condition of the working fluid for detecting or indicating knocks in internal-combustion engines; Units comprising pressure-sensitive members combined with ignitors for firing internal-combustion engines for detecting or indicating knocks in internal combustion engines using piezoelectric devices
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01M—TESTING STATIC OR DYNAMIC BALANCE OF MACHINES OR STRUCTURES; TESTING OF STRUCTURES OR APPARATUS, NOT OTHERWISE PROVIDED FOR
    • G01M15/00—Testing of engines
    • G01M15/04—Testing internal-combustion engines
    • G01M15/08—Testing internal-combustion engines by monitoring pressure in cylinders
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02D—CONTROLLING COMBUSTION ENGINES
    • F02D41/00—Electrical control of supply of combustible mixture or its constituents
    • F02D41/24—Electrical control of supply of combustible mixture or its constituents characterised by the use of digital means
    • F02D41/26—Electrical control of supply of combustible mixture or its constituents characterised by the use of digital means using computer, e.g. microprocessor
    • F02D41/28—Interface circuits
    • F02D2041/281—Interface circuits between sensors and control unit
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02D—CONTROLLING COMBUSTION ENGINES
    • F02D41/00—Electrical control of supply of combustible mixture or its constituents
    • F02D41/24—Electrical control of supply of combustible mixture or its constituents characterised by the use of digital means
    • F02D41/26—Electrical control of supply of combustible mixture or its constituents characterised by the use of digital means using computer, e.g. microprocessor
    • F02D41/28—Interface circuits
    • F02D2041/281—Interface circuits between sensors and control unit
    • F02D2041/285—Interface circuits between sensors and control unit the sensor having a signal processing unit external to the engine control unit

Definitions

  • the invention relates to a method for determining an offset of an output signal of an evaluation circuit integrated in a sensor, preferably a combustion chamber pressure sensor installed in a combustion chamber of an internal combustion engine, in which the output signal is fed to a control unit which evaluates the output signal, wherein before each Measurement of the sensor a reset of the evaluation circuit to adjust the output signal to a base level is performed and a sensor.
  • Today glow plugs are used, which include a pressure sensor, which measure the cylinder pressure during combustion of a fuel-air mixture in an internal combustion engine.
  • the pressure sensor comprehensive glow plugs have an evaluation circuit, which is connected downstream of the pressure sensor in the glow plug.
  • the pressure sensor operates on the basis of a piezoelectric measuring method, wherein the detected pressure is converted into an electrical output signal which is output and detected by an engine control unit. Due to the piezoelectric measuring method, the evaluation circuit downstream of the pressure sensor must be reset to zero level before each combustion process by means of an internal algorithm in order to avoid a drift in the output signal.
  • the invention is thus based on the object of specifying a method for determining an offset of an output signal of the evaluation circuit integrated in a sensor, in which the offset shift of the output signal which takes place on a reset is reliably determined.
  • the object is achieved in that the controller determines the offset of the output signal of the evaluation circuit as a result of a given by the evaluation circuit start signal. Due to the determination of the offset in the control unit can be dispensed with additional processing units in the evaluation of the sensor, which has a cost-reducing effect. The determination of the offset in the engine control unit is carried out without additional hardware effort, since the existing means in the engine control unit for software evaluation of the offset can be used. Thus, by the engine control unit, the offset of the output signal of the evaluation circuit can be easily determined.
  • the start signal is in a, preferably short-term, applying a predetermined level to the output signal of the evaluation circuit.
  • the start signal is generated for the determination of the offset of the output signal in the control unit and thus in a simple manner in the evaluation circuit.
  • the predetermined level of the output signal corresponds to the level of the ground terminal of the evaluation circuit.
  • the controller detects the reset at the right time and can perform the offset determination.
  • the control unit carries out the calculation of the offset in a defined period of time, wherein the period is started in particular immediately after the start signal has been received.
  • the offset of the output signal is thereby actively triggered by the sensor alone.
  • the start signal is triggered by an internal reset of the evaluation circuit. Since this reset is already provided in the evaluation circuit, eliminates an additional circuit element.
  • the defined period of time is selected such that a diagnosis of the output signal of the evaluation circuit that is running in the control unit is not recognized. Thus, diagnoses remaining in the control unit remain unimpaired by the offset determination of the control unit.
  • a currently determined output signal of the evaluation circuit is corrected.
  • the pressure actually occurring during a combustion process in the combustion chamber of the internal combustion engine can thus be determined and further processed at any time.
  • a refinement of the invention relates to a sensor, preferably a combustion chamber pressure sensor installed in a combustion chamber of an internal combustion engine, comprising an evaluation circuit which sends an output signal to a control unit for evaluation, wherein a reset of the evaluation circuit for adjusting the output signal to a base level is carried out before each measuring operation of the sensor becomes.
  • a sensor which enables a reliable determination of the offset of the output signal of the evaluation circuit
  • These means include simple circuits that do not require higher intelligence comparable to a bus system.
  • the means comprise a switching logic which applies the start signal to an output of the evaluation circuit.
  • This simple switching logic can be easily inserted in a trained as ASIC evaluation in the course of a pattern revision.
  • the switching logic is designed as a transistor.
  • the use of a transistor allows a cost-effective design of the circuit, which is structurally very easy to inject into the evaluation circuit.
  • the switching logic is preceded by a flip-flop for setting a defined period for determining the offset.
  • the use of the flip-flop for controlling the switching logic in the evaluation of the sensor leads to an active signaling against the control unit, which determines the offset after receiving these signals.
  • a further development of the invention relates to a control unit for determining an offset of an output signal of an evaluation circuit integrated in a sensor, preferably a combustion chamber pressure sensor installed in a combustion chamber of an internal combustion engine, which evaluates an output signal of the evaluation circuit.
  • a control unit which can easily determine an offset of the output signal of the evaluation circuit, means are provided which determine an offset of the output signal of the evaluation circuit after detection of a signal output by the evaluation of the sensor start signal.
  • the means determines the offset in a time period predetermined by a duration of the occurrence of the start signal.
  • the operation of the controller is controlled by the active output of the reset by the evaluation circuit.
  • the control unit does not require any additional intelligence in this procedure.
  • the means preferably a microprocessor, correct a currently measured output signal of the evaluation circuit with the offset and supply the corrected output signal to the further evaluation. As a result of this correction, the actual value of the pressure measured by the sensor in the combustion chamber of the internal combustion engine is always present for further evaluation.
  • Figure 1 Schematic representation of the arrangement of a glow plug in an internal combustion engine
  • Figure 2 an output signal of the evaluation circuit over a crankshaft angle range after an internal sensor reset
  • Figure 3 schematic representation of the evaluation circuit of the sensor
  • Figure 4 schematic sequence of the signal processing in a control unit
  • starting aid for the ignition of the fuel-air mixture introduced in the diesel engine at ambient temperatures of ⁇ 40 ° C.
  • glow systems consist of glow plugs, a Glühzeit Kunststoff Congress and a
  • Annealing software which is stored in an engine control unit, exist.
  • FIG. 1 shows such an annealing system 1 schematically.
  • the glow plug 2 protrudes into the combustion chamber 3 of the diesel engine 4.
  • the glow plug 2 is on the one hand connected to the Glühzeit Kunststoff 5 and on the other hand leads to a vehicle electrical system voltage 6, which drives the glow plug 2 with a rated voltage of, for example, 4.4 or 7 volts.
  • the Glühzeit Kunststoffbericht 5 is connected to the engine control unit 7, which in turn leads to the diesel engine 4.
  • a combustion chamber pressure sensor 8 is integrated, which thus also projects into the combustion chamber 3 of the diesel engine 4 and which with the
  • Engine control unit 7 is connected.
  • the combustion chamber pressure sensor 8 operates according to a piezoelectric measuring method, wherein the pressure detected by the combustion chamber pressure sensor 8 is converted into an electrical output signal which is detected by the engine control unit 7.
  • Figure 2 shows a representation of the course of the combustion chamber pressure p, which is measured by the combustion chamber pressure sensor 8, over a crankshaft angle range.
  • the combustion chamber pressure p assumes a maximum in a running in the combustion chamber 3 of the diesel engine 4 combustion of the fuel-air mixture and then flattens again.
  • an evaluation circuit 9 an internal
  • Reset R performed, which causes a jump in the output signal A of the integrated circuit in the combustion chamber pressure sensor 8 evaluation 9, which is illustrated in Figure 2 with ⁇ and the output signal A falsified by this offset.
  • the evaluation circuit 9 arranged in the combustion chamber pressure sensor 8 is shown in FIG. This connects to the combustion chamber pressure sensor 8 with a charge amplifier 10, which in turn is connected to a monoflop 1 1. Between the charge amplifier 10 and the monoflop 1 1, a reference voltage 12 of 0.7 volts is arranged in an input of the monoflop 1 1, which is connected to ground. The monoflop 1 1 leads to the output 14 of the evaluation circuit 9, at which the output signal A is removed from the engine control unit 7. Between the output of the monoflop 1 1 and the output 14, a transistor 13 is provided, which is triggered by the charge amplifier 10.
  • the charge amplifier 10 includes a reset logic and sets the output of the evaluation circuit 9 before each new combustion, which is to be detected by the glow plug 2 and the combustion chamber pressure sensor 8 in the combustion chamber 3 of the diesel engine 4 to ground. This reduces the level of the output signal A of the evaluation circuit 9 for the time duration during which the monoflop 1 1 is active. This brief pulling down of the
  • Level of the output signal A is detected at the output 14 by the engine control unit 7 and evaluated as a start signal for determining the offset of the output signal A of the evaluation circuit.
  • the motor controller 7 starts the offset detection and at the same time the offset compensation.
  • the output signal A of the evaluation circuit 9 is referred to ground in a simple manner.
  • This switching instant takes place directly with the reset R of the integrator stage, which is contained in the charge amplifier 10.
  • the reset R is followed by the defined period of time ⁇ t, for example in the range of a few tens of seconds.
  • This period At is determined by the monoflop 1 1, which is also triggered by the internal reset R.
  • the jump of the output signal A to ground generates an edge of the output signal A at the output 14 of the evaluation circuit 9, which starts a counter 16 in the engine control unit 7 (FIG. 4).
  • the counter 16 counts a predetermined number of signal values of the output voltage A of
  • Evaluation circuit 9 which are written in an array 17. Once the required number of signal values has been reached in the array 17, in an offset calculation 18, the signal values stored in the array 17 are input
  • Mean value is formed, which is compared with a nominal offset of, for example, 0.7 volts. The difference between the calculated mean and the
  • Nominaloffset forms the offset 19 of the output signal A of
  • Combustion chamber pressure sensor 8 measured pressure in the combustion chamber 3 of the diesel engine 4 corresponds. The corrected output signal A k is then fed to the further evaluation.
  • Engine control unit 7 does not have to be done.
  • the proposed solution is application neutral.
  • the engine control unit 7 recognizes by the executed by the evaluation circuit 9 Reset R the right time to determine the offset. During the At period, a new offset is determined, and for the remainder of the cycle, this new offset becomes the current one

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Computer Hardware Design (AREA)
  • Microelectronics & Electronic Packaging (AREA)
  • Measuring Fluid Pressure (AREA)
  • Combined Controls Of Internal Combustion Engines (AREA)

Abstract

The invention relates to a method for determining an offset of an output signal of an evaluation circuit integrated in a sensor, preferably of a combustion chamber pressure sensor (8) installed in a combustion chamber (3) of an internal combustion engine (4), in which combustion chamber pressure sensor the output signal (A) is fed to a control unit (7), which evaluates the output signal (A), wherein a reset (R) of the evaluation circuit (9) for calibrating the output signal (A) to a base level is performed before each measurement process of the sensor (8). In a method in which the offset of the output signal can be determined especially accurately and simply, the control unit (7) determines the offset of the output signal (A) of the evaluation circuit (9) as a result of a start signal output by the evaluation circuit (9).

Description

Beschreibung  description
Titel title
Verfahren zur Bestimmung eines Offsets eines Ausgangssignales einer, in einem Sensor integrierten Auswerteschaltung, vorzugsweise eines in einem Brennraum einer Brennkraftmaschine verbauten Drucksensors und ein Sensor Method for determining an offset of an output signal of an evaluation circuit integrated in a sensor, preferably a pressure sensor installed in a combustion chamber of an internal combustion engine, and a sensor
Stand der Technik Die Erfindung betrifft ein Verfahren zur Bestimmung eines Offsets eines Ausgangssignales einer in einem Sensor integrierten Auswerteschaltung, vorzugsweise eines in einem Brennraum einer Brennkraftmaschine verbauten Brenn- raumdrucksensors, bei welchem das Ausgangssignal einem Steuergerät zugeführt wird, welches das Ausgangssignal auswertet, wobei vor jedem Messvor- gang des Sensors ein Reset der Auswerteschaltung zum Abgleich des Ausgangssignales auf ein Basisniveau durchgeführt wird sowie ein Sensor. PRIOR ART The invention relates to a method for determining an offset of an output signal of an evaluation circuit integrated in a sensor, preferably a combustion chamber pressure sensor installed in a combustion chamber of an internal combustion engine, in which the output signal is fed to a control unit which evaluates the output signal, wherein before each Measurement of the sensor a reset of the evaluation circuit to adjust the output signal to a base level is performed and a sensor.
Heute werden Glühstiftkerzen verwendet, die einen Drucksensor umfassen, welcher den Zylinderdruck während der Verbrennung eines Kraftstoff-Luft- Gemisches in einer Brennkraftmaschine messen. Solche, den Drucksensor umfassende Glühstiftkerzen besitzen eine Auswerteschaltung, die dem Drucksensor in der Glühstiftkerze nachgeschaltet ist. Der Drucksensor arbeitet auf der Basis eines piezoelektrischen Messverfahrens, wobei der detektierte Druck in ein elektrisches Ausgangssignal umgewandelt wird, welches ausgegeben und von einem Motorsteuergerät erfasst wird. Bedingt durch das piezoelektrische Messverfahren muss die dem Drucksensor nachgeschaltete Auswerteschaltung vor jedem Verbrennungsvorgang anhand eines internen Algorithmus auf Nullniveau zurückgesetzt werden, um einen Drift des Ausgangssignals zu vermeiden. Today glow plugs are used, which include a pressure sensor, which measure the cylinder pressure during combustion of a fuel-air mixture in an internal combustion engine. Such, the pressure sensor comprehensive glow plugs have an evaluation circuit, which is connected downstream of the pressure sensor in the glow plug. The pressure sensor operates on the basis of a piezoelectric measuring method, wherein the detected pressure is converted into an electrical output signal which is output and detected by an engine control unit. Due to the piezoelectric measuring method, the evaluation circuit downstream of the pressure sensor must be reset to zero level before each combustion process by means of an internal algorithm in order to avoid a drift in the output signal.
Aufgrund der eingangsseitigen elektrischen Beschaltung der Auswerteschaltung des Drucksensors kann es passieren, dass das Ausgangssignal nach einem in- ternen Reset einen Sprung nach höheren oder nach niedrigeren Spannungswerten aufweist. Hervorgerufen werden diese Sprünge durch Störsignale am Eingang einer Integratorstufe der Auswerteschaltung zum Zeitpunkt direkt nach dem Rücksetzen des Integrators. Due to the input-side electrical wiring of the evaluation circuit of the pressure sensor, it may happen that the output signal after a domestic Reset has a jump to higher or lower voltage values. These jumps are caused by interference signals at the input of an integrator stage of the evaluation circuit at the time directly after the resetting of the integrator.
Aufgrund der Signalsprünge nach dem Reset kommt es zu einer Offsetverschie- bung des gesamten Drucksignals und somit auch des als Spannung gelieferten Ausgangssignals des Drucksensors im darauf folgenden Zyklus. Due to the signal jumps after the reset, there is an offset shift of the entire pressure signal and thus also of the output signal of the pressure sensor delivered as voltage in the subsequent cycle.
Offenbarung der Erfindung Disclosure of the invention
Der Erfindung liegt somit die Aufgabe zugrunde, ein Verfahren zur Bestimmung eines Offsets eines Ausgangssignales der in einem Sensor integrierten Auswerteschaltung anzugeben, bei welchem die auf einen Reset erfolgende Offsetverschiebung des Ausgangssignals zuverlässig bestimmt wird. The invention is thus based on the object of specifying a method for determining an offset of an output signal of the evaluation circuit integrated in a sensor, in which the offset shift of the output signal which takes place on a reset is reliably determined.
Erfindungsgemäß wird die Aufgabe dadurch gelöst, dass das Steuergerät infolge eines von der Auswerteschaltung abgegebenen Startsignals den Offset des Ausgangssignals der Auswerteschaltung bestimmt. Aufgrund der Bestimmung des Offsets in dem Steuergerät kann auf zusätzliche Recheneinheiten in der Auswerteschaltung des Sensors verzichtet werden, was sich kostenreduzierend auswirkt. Die Bestimmung des Offsets im Motorsteuergerät erfolgt dabei ohne zusätzlichen hardwaremäßigen Aufwand, da die im Motorsteuergerät vorhandenen Mittel zur softwaremäßigen Auswertung des Offsets genutzt werden. Somit kann durch das Motorsteuergerät der Offset des Ausgangssignals der Auswerteschaltung einfach bestimmt werden. According to the invention the object is achieved in that the controller determines the offset of the output signal of the evaluation circuit as a result of a given by the evaluation circuit start signal. Due to the determination of the offset in the control unit can be dispensed with additional processing units in the evaluation of the sensor, which has a cost-reducing effect. The determination of the offset in the engine control unit is carried out without additional hardware effort, since the existing means in the engine control unit for software evaluation of the offset can be used. Thus, by the engine control unit, the offset of the output signal of the evaluation circuit can be easily determined.
Vorteilhafterweise besteht das Startsignal in einem, vorzugsweise kurzzeitigen, Anlegen eines vorgegebenen Pegels an das Ausgangssignal der Auswerteschaltung. Das Startsignal wird für die Bestimmung des Offsets des Ausgangssignals im Steuergerät und somit auf einfache Art und Weise in der Auswerteschaltung erzeugt. Advantageously, the start signal is in a, preferably short-term, applying a predetermined level to the output signal of the evaluation circuit. The start signal is generated for the determination of the offset of the output signal in the control unit and thus in a simple manner in the evaluation circuit.
In einer Ausgestaltung entspricht der vorgegebene Pegel des Ausgangssignals dem Pegel des Masseanschlusses der Auswerteschaltung. Durch das kurzzeitige einfache Herabziehen des aktuellen Pegels des Ausgangssignals auf das Niveau des Masseanschlusses wird dem Steuergerät signalisiert, dass ein Reset vorgenommen wurde. Somit erkennt das Steuergerät den Reset zum richtigen Zeitpunkt und kann die Offsetbestimmung durchführen. In einer Variante führt das Steuergerät nach Empfang des Startsignals in einem definierten Zeitraum die Berechnung des Offsets durch, wobei der Zeitraum insbesondere unmittelbar nach Empfang des Startsignals gestartet wird. Somit wird in dem Zeitraum, in welchem der Pegel des Ausgangssignals auf Massean- schluss liegt, im Steuergerät der Offset des Ausgangssignals berechnet. Die Off- setbestimmung innerhalb des zum Sensor extern angeordneten Steuergerätes wird dabei allein aktiv durch den Sensor ausgelöst. In one embodiment, the predetermined level of the output signal corresponds to the level of the ground terminal of the evaluation circuit. By briefly simply lowering the current level of the output signal to the level of the ground connection is signaled to the controller that a reset has been made. Thus, the controller detects the reset at the right time and can perform the offset determination. In one variant, after receiving the start signal, the control unit carries out the calculation of the offset in a defined period of time, wherein the period is started in particular immediately after the start signal has been received. Thus, in the period in which the level of the output signal is grounded, calculated in the control unit, the offset of the output signal. The offset determination within the control unit arranged externally to the sensor is thereby actively triggered by the sensor alone.
In einer Variante wird das Startsignal durch einen internen Reset der Auswerteschaltung ausgelöst. Da dieser Reset bereits in der Auswerteschaltung vorgesehen ist, entfällt ein zusätzliches Schaltungselement. In one variant, the start signal is triggered by an internal reset of the evaluation circuit. Since this reset is already provided in the evaluation circuit, eliminates an additional circuit element.
In einer Weiterbildung wird der definierte Zeitraum so gewählt, dass eine im Steuergerät ablaufende Diagnose des Ausgangssignals der Auswerteschaltung nicht erkannt wird. Somit bleiben im Steuergerät vorhandene Diagnosen durch die Offsetbestimmung des Steuergerätes unbeeinträchtigt. In a further development, the defined period of time is selected such that a diagnosis of the output signal of the evaluation circuit that is running in the control unit is not recognized. Thus, diagnoses remaining in the control unit remain unimpaired by the offset determination of the control unit.
Ferner wird mit dem berechneten Offset ein aktuell bestimmtes Ausgangssignal der Auswerteschaltung korrigiert. Mittels dieses korrigierten Ausgangssignals kann somit jederzeit der tatsächlich während eines Verbrennungsprozesses im Brennraum der Brennkraftmaschine auftretende Druck ermittelt und weiterverarbeitet werden. Furthermore, with the calculated offset, a currently determined output signal of the evaluation circuit is corrected. By means of this corrected output signal, the pressure actually occurring during a combustion process in the combustion chamber of the internal combustion engine can thus be determined and further processed at any time.
Eine Weiterbildung der Erfindung betrifft einen Sensor, vorzugsweise einen in einem Brennraum einer Brennkraftmaschine verbauten Brennraumdrucksensor, umfassend eine Auswerteschaltung, welche ein Ausgangssignal zur Auswertung an ein Steuergerät sendet, wobei vor jedem Messvorgang des Sensors ein Reset der Auswerteschaltung zum Abgleich des Ausgangssignales auf ein Basisniveau durchgeführt wird. Bei einem Sensor, welcher eine zuverlässige Bestimmung des Offsets des Ausgangssignals der Auswerteschaltung ermöglicht, sind Mittel vorhanden, welche an das Steuergerät ein von der Auswerteschaltung abgegebenes Startsignal zur Bestimmung des Offsets des Ausgangssignals der Auswerteschaltung ausgeben. Diese Mittel umfassen dabei einfache Schaltungen, die keine höhere Intelligenz vergleichbar mit einem Bussystem erfordern. A refinement of the invention relates to a sensor, preferably a combustion chamber pressure sensor installed in a combustion chamber of an internal combustion engine, comprising an evaluation circuit which sends an output signal to a control unit for evaluation, wherein a reset of the evaluation circuit for adjusting the output signal to a base level is carried out before each measuring operation of the sensor becomes. In a sensor which enables a reliable determination of the offset of the output signal of the evaluation circuit, there are means which send to the control unit a starting signal output by the evaluation circuit for determining the offset of the output signal of the Output evaluation circuit. These means include simple circuits that do not require higher intelligence comparable to a bus system.
Vorteilhafterweise umfassen die Mittel eine Schaltlogik, welche das Startsignal an einen Ausgang der Auswerteschaltung anlegt. Diese einfache Schaltlogik kann im Zuge einer Musterüberarbeitung einfach in einer als ASIC ausgebildeten Auswerteschaltung eingefügt werden. Advantageously, the means comprise a switching logic which applies the start signal to an output of the evaluation circuit. This simple switching logic can be easily inserted in a trained as ASIC evaluation in the course of a pattern revision.
In einer Variante ist die Schaltlogik als Transistor ausgebildet. Die Verwendung eines Transistors erlaubt eine kostengünstige Ausgestaltung der Schaltung, die auch konstruktiv sehr einfach in die Auswerteschaltung einpflegbar ist. In a variant, the switching logic is designed as a transistor. The use of a transistor allows a cost-effective design of the circuit, which is structurally very easy to inject into the evaluation circuit.
In einer Ausgestaltung ist der Schaltlogik eine Kippschaltung zur Einstellung eines definierten Zeitraumes zur Offsetbestimmung vorgeschaltet. Die Verwendung der Kippschaltung zur Ansteuerung der Schaltlogik in der Auswerteschaltung des Sensors führt zu einer aktiven Signalgebung gegenüber dem Steuergerät, welches nach Empfang dieser Signale den Offset bestimmt. In one embodiment, the switching logic is preceded by a flip-flop for setting a defined period for determining the offset. The use of the flip-flop for controlling the switching logic in the evaluation of the sensor leads to an active signaling against the control unit, which determines the offset after receiving these signals.
Eine weitere Weiterbildung der Erfindung betrifft ein Steuergerät zur Bestimmung eines Offsets eines Ausgangssignales einer in einem Sensor integrierten Auswerteschaltung, vorzugsweise eines in einem Brennraum einer Brennkraftmaschine verbauten Brennraumdrucksensors, welches ein Ausgangssignal der Auswerteschaltung auswertet. Bei einem Steuergerät, was einfach einen Offset des Ausgangssignals der Auswerteschaltung bestimmen kann, sind Mittel vorhanden, welche nach Detektion eines von der Auswerteschaltung des Sensors ausgegebenen Startsignals einen Offset des Ausgangssignals der Auswerteschaltung bestimmen. Dies hat den Vorteil, dass die Funktion der Offsetbestimmung in die Software des Steuergerätes integriert werden kann, ohne dass eine Notwendigkeit von zusätzlichen Hardwareelementen besteht. A further development of the invention relates to a control unit for determining an offset of an output signal of an evaluation circuit integrated in a sensor, preferably a combustion chamber pressure sensor installed in a combustion chamber of an internal combustion engine, which evaluates an output signal of the evaluation circuit. In a control unit, which can easily determine an offset of the output signal of the evaluation circuit, means are provided which determine an offset of the output signal of the evaluation circuit after detection of a signal output by the evaluation of the sensor start signal. This has the advantage that the function of the offset determination can be integrated into the software of the control unit without the need for additional hardware elements.
In einer weiteren Ausführungsform bestimmen die Mittel den Offset in einem Zeitraum, der durch eine Dauer des Auftretens des Startsignals vorgegeben ist. Die Arbeitsweise des Steuergerätes wird dabei durch die aktive Ausgabe des Resets durch die Auswerteschaltung gesteuert. Das Steuergerät benötigt bei diesem Vorgehen keine zusätzliche Intelligenz. Insbesondere korrigieren die Mittel, vorzugsweise ein Mikroprozessor, ein aktuell gemessenes Ausgangssignal der Auswerteschaltung mit dem Offset und führen das korrigierte Ausgangssignal der weiteren Auswertung zu. Infolge dieser Korrektur liegt immer der tatsächliche Wert des vom Sensor gemessenen Druckes im Brennraum der Brennkraftmaschine zur weiteren Auswertung vor. In another embodiment, the means determines the offset in a time period predetermined by a duration of the occurrence of the start signal. The operation of the controller is controlled by the active output of the reset by the evaluation circuit. The control unit does not require any additional intelligence in this procedure. In particular, the means, preferably a microprocessor, correct a currently measured output signal of the evaluation circuit with the offset and supply the corrected output signal to the further evaluation. As a result of this correction, the actual value of the pressure measured by the sensor in the combustion chamber of the internal combustion engine is always present for further evaluation.
Die Erfindung lässt zahlreiche Ausführungsformen zu. Eine davon soll anhand der in der Zeichnung dargestellten Figuren näher erläutert werden. Es zeigt: The invention allows numerous embodiments. One of them will be explained in more detail with reference to the figures shown in the drawing. It shows:
Figur 1 : Prinzipdarstellung der Anordnung einer Glühstiftkerze in einem Verbrennungsmotor Figur 2: ein Ausgangssignal der Auswerteschaltung über einem Kurbelwellen- winkelbereich nach einem internen Sensorreset Figure 1: Schematic representation of the arrangement of a glow plug in an internal combustion engine Figure 2: an output signal of the evaluation circuit over a crankshaft angle range after an internal sensor reset
Figur 3: schematische Darstellung der Auswerteschaltung des Sensors Figur 4: schematischer Ablauf der Signalaufbereitung in einem Steuergerät Figure 3: schematic representation of the evaluation circuit of the sensor Figure 4: schematic sequence of the signal processing in a control unit
Kalte Verbrennungsmotoren, insbesondere Dieselmotoren, benötigen bei Umgebungstemperaturen von <40°C eine Starthilfe zur Zündung des in dem Dieselmotor eingeleiteten Kraftstoff-Luft-Gemisches. Als Starthilfe werden Glühsysteme eingesetzt, welche aus Glühstiftkerzen, einem Glühzeitsteuergerät und einerCold internal combustion engines, in particular diesel engines, require a starting aid for the ignition of the fuel-air mixture introduced in the diesel engine at ambient temperatures of <40 ° C. As starting aid, glow systems are used, which consist of glow plugs, a Glühzeitsteuergerät and a
Glühsoftware, die in einem Motorsteuergerät abgelegt ist, bestehen. Annealing software, which is stored in an engine control unit, exist.
Figur 1 zeigt ein solches Glühsystem 1 schematisch. Die Glühstiftkerze 2 ragt dabei in den Brennraum 3 des Dieselmotors 4. Die Glühstiftkerze 2 ist einerseits mit dem Glühzeitsteuergerät 5 verbunden und führt andererseits an eine Bordnetzspannung 6, die die Glühstiftkerze 2 mit einer Nennspannung von beispielsweise 4,4 oder 7 Volt ansteuert. Das Glühzeitsteuergerät 5 ist mit dem Motorsteuergerät 7 verbunden, welches wiederum an den Dieselmotor 4 führt. Darüber hinaus ist in die Glühstiftkerze 2 ein Brennraumdrucksensor 8 integriert, der so- mit ebenfalls in den Brennraum 3 des Dieselmotors 4 ragt und welcher mit demFIG. 1 shows such an annealing system 1 schematically. The glow plug 2 protrudes into the combustion chamber 3 of the diesel engine 4. The glow plug 2 is on the one hand connected to the Glühzeitsteuergerät 5 and on the other hand leads to a vehicle electrical system voltage 6, which drives the glow plug 2 with a rated voltage of, for example, 4.4 or 7 volts. The Glühzeitsteuergerät 5 is connected to the engine control unit 7, which in turn leads to the diesel engine 4. In addition, in the glow plug 2, a combustion chamber pressure sensor 8 is integrated, which thus also projects into the combustion chamber 3 of the diesel engine 4 and which with the
Motorsteuergerät 7 verbunden ist. Der Brennraumdrucksensor 8 arbeitet dabei nach einem piezoelektrischen Messverfahren, wobei der von dem Brennraum- drucksensor 8 erfasste Druck in ein elektrisches Ausgangssignal umgewandelt wird, welches durch das Motorsteuergerät 7 erfasst wird. Figur 2 zeigt eine Darstellung des Verlaufes des Brennraumdruckes p, welcher von dem Brennraumdrucksensor 8 gemessen wird, über einem Kurbelwellenwin- kelbereich. Der Brennraumdruck p nimmt dabei bei einer in dem Brennraum 3 des Dieselmotors 4 ablaufenden Verbrennung des Kraftstoff-Luft-Gemisches ein Maximum ein und flacht dann wiederum ab. Vor jeder neuen Messung wird in dem Brennraumdrucksensor 8 durch eine Auswerteschaltung 9 ein internerEngine control unit 7 is connected. The combustion chamber pressure sensor 8 operates according to a piezoelectric measuring method, wherein the pressure detected by the combustion chamber pressure sensor 8 is converted into an electrical output signal which is detected by the engine control unit 7. Figure 2 shows a representation of the course of the combustion chamber pressure p, which is measured by the combustion chamber pressure sensor 8, over a crankshaft angle range. The combustion chamber pressure p assumes a maximum in a running in the combustion chamber 3 of the diesel engine 4 combustion of the fuel-air mixture and then flattens again. Before each new measurement is in the combustion chamber pressure sensor 8 by an evaluation circuit 9 an internal
Reset R ausgeführt, welcher einen Sprung des Ausgangssignals A der in den Brennraumdrucksensors 8 integrierten Auswerteschaltung 9 verursacht, welcher in Figur 2 mit Δρ verdeutlicht ist und der das Ausgangssignal A um diesen Offset verfälscht. Reset R performed, which causes a jump in the output signal A of the integrated circuit in the combustion chamber pressure sensor 8 evaluation 9, which is illustrated in Figure 2 with Δρ and the output signal A falsified by this offset.
Die im Brennraumdrucksensor 8 angeordnete Auswerteschaltung 9 ist in Figur 3 dargestellt. Diese schließt sich an den Brennraumdrucksensor 8 mit einem Ladungsverstärker 10 an, welcher wiederum mit einem Monoflop 1 1 verbunden ist. Zwischen dem Ladungsverstärker 10 und dem Monoflop 1 1 ist in einem Eingang des Monoflops 1 1 eine Referenzspannung 12 von 0,7 Volt angeordnet, welche gegen Masse verschaltet ist. Der Monoflop 1 1 führt an den Ausgang 14 der Auswerteschaltung 9, an welchem das Ausgangssignal A von dem Motorsteuergerät 7 abgenommen wird. Zwischen dem Ausgang des Monoflops 1 1 und dem Ausgang 14 ist ein Transistor 13 vorgesehen, welcher von dem Ladungsverstärker 10 getriggert wird. Die Ladungsverstärker 10 beinhaltet eine Resetlogik und setzt das Ausgangssignal der Auswerteschaltung 9 vor jeder neuen Verbrennung, welche durch die Glühstiftkerze 2 und den Brennraumdrucksensor 8 im Brennraum 3 des Dieselmotors 4 detektiert werden soll, auf Masse. Damit sinkt der Pegel des Ausgangssignals A der Auswerteschaltung 9 für die Zeitdauer, wäh- rend welcher der Monoflop 1 1 aktiv ist. Dieses kurzzeitige Herunterziehen desThe evaluation circuit 9 arranged in the combustion chamber pressure sensor 8 is shown in FIG. This connects to the combustion chamber pressure sensor 8 with a charge amplifier 10, which in turn is connected to a monoflop 1 1. Between the charge amplifier 10 and the monoflop 1 1, a reference voltage 12 of 0.7 volts is arranged in an input of the monoflop 1 1, which is connected to ground. The monoflop 1 1 leads to the output 14 of the evaluation circuit 9, at which the output signal A is removed from the engine control unit 7. Between the output of the monoflop 1 1 and the output 14, a transistor 13 is provided, which is triggered by the charge amplifier 10. The charge amplifier 10 includes a reset logic and sets the output of the evaluation circuit 9 before each new combustion, which is to be detected by the glow plug 2 and the combustion chamber pressure sensor 8 in the combustion chamber 3 of the diesel engine 4 to ground. This reduces the level of the output signal A of the evaluation circuit 9 for the time duration during which the monoflop 1 1 is active. This brief pulling down of the
Pegels des Ausgangssignals A wird am Ausgang 14 durch das Motorsteuergerät 7 detektiert und als Startsignal zur Bestimmung des Offsets des Ausgangssignals A der Auswerteschaltung gewertet. In dem Zeitraum At, in welchem das Ausgangssignal A durch den Transistor 13 auf Masse gesetzt wird, startet das Mo- torsteuergerät 7 die Offseterkennung und gleichzeitig die Offsetkompensation.Level of the output signal A is detected at the output 14 by the engine control unit 7 and evaluated as a start signal for determining the offset of the output signal A of the evaluation circuit. In the period At, in which the output signal A is grounded by the transistor 13, the motor controller 7 starts the offset detection and at the same time the offset compensation.
Das Schalten nach Masse erzeugt keinerlei E MV-Störungen, da zum Zeitpunkt des Schaltens der Pegel des Ausgangssignales A bereits sehr niedrig ist (700 mV oder kleiner). Switching to ground does not produce any E MV disturbances since at the time the switching of the levels of the output signal A is already very low (700 mV or less).
Durch das Einbringen des Schalttransistors 13 in die Auswerteschaltung 9, die als ein ASIC ausgebildet ist, wird das Ausgangssignal A der Auswerteschaltung 9 in einfacher Art und Weise auf Masse bezogen. Dieser Schaltzeitpunkt erfolgt unmittelbar mit dem Reset R der Integratorstufe, welche im Ladungsverstärker 10 enthalten ist. An den Reset R schließt sich der definierte Zeitraum At, beispielsweise im Bereich von einigen 10 s, an. Dieser Zeitraum At wird durch den Monoflop 1 1 bestimmt, der durch den internen Reset R ebenfalls ausgelöst wird. By introducing the switching transistor 13 in the evaluation circuit 9, which is designed as an ASIC, the output signal A of the evaluation circuit 9 is referred to ground in a simple manner. This switching instant takes place directly with the reset R of the integrator stage, which is contained in the charge amplifier 10. The reset R is followed by the defined period of time Δt, for example in the range of a few tens of seconds. This period At is determined by the monoflop 1 1, which is also triggered by the internal reset R.
Der Sprung des Ausgangssignales A auf Masse generiert eine Flanke des Ausgangssignals A am Ausgang 14 der Auswerteschaltung 9, welche in dem Motorsteuergerät 7 einen Zähler 16 startet (Figur 4). Der Zähler 16 zählt eine vorgegebene Anzahl von Signalwerten der Ausgangsspannung A der The jump of the output signal A to ground generates an edge of the output signal A at the output 14 of the evaluation circuit 9, which starts a counter 16 in the engine control unit 7 (FIG. 4). The counter 16 counts a predetermined number of signal values of the output voltage A of
Auswerteschaltung 9, welche in ein Array 17 geschrieben werden. Ist die benötigte Anzahl von Signalwerten in dem Array 17 erreicht, wird in einer Offsetberechnung 18 aus den, im Array 17 abgelegten Signalwerten ein  Evaluation circuit 9, which are written in an array 17. Once the required number of signal values has been reached in the array 17, in an offset calculation 18, the signal values stored in the array 17 are input
Mittelwert gebildet, welcher mit einem Nominaloffset von beispielsweise 0,7 Volt verglichen wird. Die Differenz zwischen dem berechneten Mittelwert und demMean value is formed, which is compared with a nominal offset of, for example, 0.7 volts. The difference between the calculated mean and the
Nominaloffset bildet den Offset 19 des Ausgangssignals A der Nominaloffset forms the offset 19 of the output signal A of
Auswerteschaltung 9, welcher durch den Sprung des Ausgangssignals A verursacht wird. Dieser Offset 19 wird von dem aktuell am Ausgang 14 der Auswerteschaltung 9 anliegenden Ausgangssignal A im Punkt 20 subtrahiert. Durch diese Subtraktion wird ein korrigiertes Ausgangssignal Ak in dem Evaluation circuit 9, which is caused by the jump of the output signal A. This offset 19 is subtracted from the output signal A currently present at the output 14 of the evaluation circuit 9 at point 20. By this subtraction, a corrected output signal A k in the
Motorsteuergerät 7 berechnet, welches dem tatsächlich von dem  Engine control unit 7 calculated, which is actually from the
Brennraumdrucksensor 8 gemessenen Druck im Brennraum 3 des Dieselmotors 4 entspricht. Das korrigierte Ausgangssignal Ak wird anschließend der weiteren Auswertung zugeführt. Combustion chamber pressure sensor 8 measured pressure in the combustion chamber 3 of the diesel engine 4 corresponds. The corrected output signal A k is then fed to the further evaluation.
Durch die Wahl des geeigneten Zeitraumes At des Monoflops, welche gleichzeitig dem Offsetauswertezeitraum des Motorsteuergerätes 7 entspricht, ist es möglich, dass eine Signaldiagnose„Signal-unter-Minimum" in dem By selecting the appropriate period At of the monoflop, which simultaneously corresponds to the offset evaluation period of the engine control unit 7, it is possible that a signal diagnosis "signal below minimum" in the
Motorsteuergerät 7 nicht erfolgen muss. Somit ist die vorgeschlagene Lösung applikationsneutral. Durch dieses Verfahren bleiben an sich im MotorsteuergerätEngine control unit 7 does not have to be done. Thus, the proposed solution is application neutral. By this method remain in the engine control unit
7 vorhandene Diagnosen unbeeinträchtigt. Das Motorsteuergerät 7 erkennt durch den, von der Auswerteschaltung 9 ausgeführten Reset R den richtigen Zeitpunkt zur Bestimmung des Offsets. Während des Zeitraumes At wird ein neuer Offset ermittelt und für den darauffolgenden Restzyklus wird dieser neue Offset von dem aktuellen7 existing diagnoses undisturbed. The engine control unit 7 recognizes by the executed by the evaluation circuit 9 Reset R the right time to determine the offset. During the At period, a new offset is determined, and for the remainder of the cycle, this new offset becomes the current one
Ausgangssignal A abgezogen. Output signal A deducted.

Claims

Ansprüche claims
Verfahren zur Bestimmung eines Offsets eines Ausgangssignales einer in einem Sensor integrierten Auswerteschaltung, vorzugsweise eines in einem Brennraum (3) einer Brennkraftmaschine (4) verbauten Brennraumdruck- sensors (8), bei welchem das Ausgangssignal (A) einem Steuergerät (7) zugeführt wird, welches das Ausgangssignal (A) auswertet, wobei vor jedem Messvorgang des Sensors (8) ein Reset (R) der Auswerteschaltung (9) zum Abgleich des Ausgangssignales (A) auf ein Basisniveau durchgeführt wird, dadurch gekennzeichnet, dass das Steuergerät (7) infolge eines von der Auswerteschaltung (9) abgegebenen Startsignals den Offset des Ausgangssignals (A) der Auswerteschaltung (9) bestimmt. Method for determining an offset of an output signal of an evaluation circuit integrated in a sensor, preferably a combustion chamber pressure sensor (8) installed in a combustion chamber (3) of an internal combustion engine (4), in which the output signal (A) is fed to a control unit (7), which evaluates the output signal (A), wherein before each measuring operation of the sensor (8) a reset (R) of the evaluation circuit (9) for adjusting the output signal (A) to a base level is performed, characterized in that the control unit (7) due one of the evaluation circuit (9) output signal determines the offset of the output signal (A) of the evaluation circuit (9).
Verfahren nach Anspruch 1 , dadurch gekennzeichnet, dass das Startsignal in einem, vorzugsweise kurzzeitigen, Anlegen eines vorgegebenen Pegels des Ausgangssignals (A) der Auswerteschaltung (9) besteht. A method according to claim 1, characterized in that the start signal in a, preferably short-term, applying a predetermined level of the output signal (A) of the evaluation circuit (9).
Verfahren nach Anspruch 2, dadurch gekennzeichnet, dass der vorgegebene Pegel des Ausgangssignals (A) dem Pegel des Masseanschlusses der Auswerteschaltung (9) entspricht. A method according to claim 2, characterized in that the predetermined level of the output signal (A) corresponds to the level of the ground terminal of the evaluation circuit (9).
Verfahren nach Anspruch 1 , 2 oder 3, dadurch gekennzeichnet, dass dasMethod according to claim 1, 2 or 3, characterized in that the
Steuergerät (7) nach Empfang des Startsignals in einem definierten Zeitraum (At) die Berechnung des Offsets durchführt, wobei der Zeitraum (At) insbesondere unmittelbar nach Empfang des Startsignals gestartet wird. Control unit (7) after receiving the start signal in a defined period (At) performs the calculation of the offset, wherein the period (At) is started in particular immediately after receiving the start signal.
Verfahren nach Anspruch 4, dadurch gekennzeichnet, dass der definierte Zeitraum (At) so gewählt ist, dass eine im Steuergerät (7) ablaufende Diagnose des Ausgangssignals (A) der Auswerteschaltung (9) nicht erkannt wird. Verfahren nach mindestens einem der vorhergehenden Ansprüche dadurch gekennzeichnet, dass das Startsignal durch einen internen Reset (R) der Auswerteschaltung ausgelöst wird. A method according to claim 4, characterized in that the defined period (At) is selected so that in the control unit (7) running diagnosis of the output signal (A) of the evaluation circuit (9) is not detected. Method according to at least one of the preceding claims, characterized in that the start signal is triggered by an internal reset (R) of the evaluation circuit.
Verfahren nach Anspruch 4, 5 oder 6, dadurch gekennzeichnet, dass mit dem berechneten Offset ein aktuell bestimmtes Ausgangssignal (A) der Auswerteschaltung (8) korrigiert wird. A method according to claim 4, 5 or 6, characterized in that with the calculated offset, a currently determined output signal (A) of the evaluation circuit (8) is corrected.
Sensor, vorzugsweise ein in einem Brennraum einer Brennkraftmaschine verbaute Brennraumdrucksensor, umfassend eine Auswerteschaltung (9) welche ein Ausgangssignal (A) an ein Steuergerät (7) sendet, welches das Ausgangssignal (A) auswertet, wobei vor jedem Messvorgang des Sensors (8) ein Reset (R) der Auswerteschaltung (9) zum Abgleich des Ausgangssignales (A) auf ein Basisniveau durchgeführt wird, dadurch gekennzeichnet, dass Mittel (10, 1 1 , 13) vorhanden sind, welche an das Steuergerät (7) ein von der Auswerteschaltung (9) abgegebenes Startsignal zur Bestimmung des Offsets des Ausgangssignals (A) der Auswerteschaltung (9) ausgeben. Sensor, preferably a built in a combustion chamber of an internal combustion engine combustion chamber pressure sensor, comprising an evaluation circuit (9) which sends an output signal (A) to a control unit (7) which evaluates the output signal (A), wherein before each measuring operation of the sensor (8) a Reset (R) of the evaluation circuit (9) for adjusting the output signal (A) to a base level is performed, characterized in that means (10, 1 1, 13) are present, which to the control unit (7) from the evaluation circuit ( 9) issued output signal for determining the offset of the output signal (A) of the evaluation circuit (9).
9. Vorrichtung nach Anspruch 8, dadurch gekennzeichnet, dass die Mittel (10, 1 1 , 13) eine Schaltlogik (13) umfassen, welche das Startsignal an einen9. Apparatus according to claim 8, characterized in that the means (10, 1 1, 13) comprise a switching logic (13), which the start signal to a
Ausgang (14) der Auswerteschaltung (9) anlegt. Output (14) of the evaluation circuit (9) applies.
10. Vorrichtung nach Anspruch 9, dadurch gekennzeichnet, dass die Schaltlogik als Transistor (13) ausgebildet ist. 10. The device according to claim 9, characterized in that the switching logic is designed as a transistor (13).
1 1 . Vorrichtung nach Anspruch 9 oder 10, dadurch gekennzeichnet, dass der1 1. Apparatus according to claim 9 or 10, characterized in that the
Schaltlogik (13) eine Kippschaltung (1 1 ) zur Einstellung eines definierten Zeitraumes (At) zur Offsetbestimmung vorgeschaltet ist. 12. Steuergerät zur Bestimmung eines Offsets eines Ausgangssignales einer in einem Sensor integrierten Auswerteschaltung, vorzugsweise eines in einem Brennraum (3) einer Brennkraftmaschine (4) verbauten Brennraumdruck- sensors (8), welches ein Ausgangssignal (A) der Auswerteschaltung (9) auswertet, dadurch gekennzeichnet, dass Mittel (5a) vorhanden sind, wel- che nach Detektion eines von der Auswerteschaltung (9) ausgegebenen Startsignals einen Offset des Ausgangssignals (A) der Auswerteschaltung (9) bestimmen. Switching logic (13) is a flip-flop circuit (1 1) upstream of setting a defined period (At) for determining the offset. 12. Control unit for determining an offset of an output signal of an integrated in a sensor evaluation circuit, preferably one in a combustion chamber (3) of an internal combustion engine (4) built-in combustion chamber pressure sensor (8) which evaluates an output signal (A) of the evaluation circuit (9), characterized in that there are means (5a) which, after detection, output one of the evaluation circuit (9) Start signal to determine an offset of the output signal (A) of the evaluation circuit (9).
13. Steuergerät nach Anspruch 12, dadurch gekennzeichnet, dass die Mittel (5a) den Offset in einem Zeitraum (At) bestimmen, der durch eine Dauer des Auftretens des Startsignals vorgegeben ist. 13. Control device according to claim 12, characterized in that the means (5a) determine the offset in a time period (At), which is predetermined by a duration of the occurrence of the start signal.
14. Steuergerät nach Anspruch 12 oder 13, dadurch gekennzeichnet, dass die Mittel (5a), vorzugsweise ein Mikroprozessor, ein aktuell gemessenes Ausgangssignal (A) mit dem Offset korrigieren und das korrigierte Ausgangssignal (Ak) der weiteren Auswertung zuführen. 14. Control device according to claim 12 or 13, characterized in that the means (5a), preferably a microprocessor, correct a currently measured output signal (A) with the offset and the corrected output signal (A k ) perform the further evaluation.
EP13718848.8A 2012-05-02 2013-04-26 Method for determining 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 a sensor Withdrawn EP2844971A1 (en)

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PCT/EP2013/058764 WO2013164273A1 (en) 2012-05-02 2013-04-26 Method for determining 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 a sensor

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US9518888B2 (en) 2016-12-13
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JP5868547B2 (en) 2016-02-24
DE102012207291A1 (en) 2013-11-07
WO2013164273A1 (en) 2013-11-07

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