EP3033600A1 - Air mass flow meter - Google Patents

Air mass flow meter

Info

Publication number
EP3033600A1
EP3033600A1 EP14742502.9A EP14742502A EP3033600A1 EP 3033600 A1 EP3033600 A1 EP 3033600A1 EP 14742502 A EP14742502 A EP 14742502A EP 3033600 A1 EP3033600 A1 EP 3033600A1
Authority
EP
European Patent Office
Prior art keywords
air mass
sensor element
signal characteristic
mass flow
signal
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Withdrawn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
EP14742502.9A
Other languages
German (de)
French (fr)
Inventor
Stephan Schürer
Thorsten Knittel
Stephen Setescak
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.)
Continental Automotive GmbH
Original Assignee
Continental Automotive 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 Continental Automotive GmbH filed Critical Continental Automotive GmbH
Publication of EP3033600A1 publication Critical patent/EP3033600A1/en
Withdrawn legal-status Critical Current

Links

Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01F—MEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL; METERING BY VOLUME
    • G01F1/00—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow
    • G01F1/68—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow by using thermal effects
    • G01F1/684—Structural arrangements; Mounting of elements, e.g. in relation to fluid flow
    • G01F1/688—Structural arrangements; Mounting of elements, e.g. in relation to fluid flow using a particular type of heating, cooling or sensing element
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01F—MEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL; METERING BY VOLUME
    • G01F1/00—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow
    • G01F1/68—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow by using thermal effects
    • G01F1/684—Structural arrangements; Mounting of elements, e.g. in relation to fluid flow
    • G01F1/6845—Micromachined devices
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01F—MEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL; METERING BY VOLUME
    • G01F1/00—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow
    • G01F1/68—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow by using thermal effects
    • G01F1/696—Circuits therefor, e.g. constant-current flow meters
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01F—MEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL; METERING BY VOLUME
    • G01F1/00—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow
    • G01F1/68—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow by using thermal effects
    • G01F1/696—Circuits therefor, e.g. constant-current flow meters
    • G01F1/6965—Circuits therefor, e.g. constant-current flow meters comprising means to store calibration data for flow signal calculation or correction
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01F—MEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL; METERING BY VOLUME
    • G01F25/00—Testing or calibration of apparatus for measuring volume, volume flow or liquid level or for metering by volume
    • G01F25/10—Testing or calibration of apparatus for measuring volume, volume flow or liquid level or for metering by volume of flowmeters
    • 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
    • F02D41/02—Circuit arrangements for generating control signals
    • F02D41/18—Circuit arrangements for generating control signals by measuring intake air flow
    • F02D41/187—Circuit arrangements for generating control signals by measuring intake air flow using a hot wire flow sensor
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01F—MEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL; METERING BY VOLUME
    • G01F1/00—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow
    • G01F1/68—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow by using thermal effects
    • G01F1/684—Structural arrangements; Mounting of elements, e.g. in relation to fluid flow
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01F—MEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL; METERING BY VOLUME
    • G01F1/00—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow
    • G01F1/68—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow by using thermal effects
    • G01F1/684—Structural arrangements; Mounting of elements, e.g. in relation to fluid flow
    • G01F1/6842—Structural arrangements; Mounting of elements, e.g. in relation to fluid flow with means for influencing the fluid flow
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01F—MEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL; METERING BY VOLUME
    • G01F1/00—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow
    • G01F1/68—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow by using thermal effects
    • G01F1/696—Circuits therefor, e.g. constant-current flow meters
    • G01F1/698—Feedback or rebalancing circuits, e.g. self heated constant temperature flowmeters
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01F—MEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL; METERING BY VOLUME
    • G01F5/00—Measuring a proportion of the volume flow

Definitions

  • the invention relates to an air-mass meter with a sensor element for detecting an air mass flow and He ⁇ generating a signal and with an electronic circuit for processing the signal from the sensor element, the sensor ⁇ element produces a non-linear signal characteristic. Furthermore, the invention relates to a method for processing
  • Air mass meters are suitable for detecting a mass flow of a fluid (air mass flow) in a flow channel.
  • a flow channel can be for example an air intake pipe ⁇ an internal combustion engine.
  • an internal combustion engine Depending on the value detected by the air mass meter mass flow both diagnoses, for example, the operation of the internal combustion engine Runaway ⁇ leads can be also be performed as a control of the internal combustion engine. For these purposes, also under different operating conditions reliable and accurate as possible, he ⁇ grasp the actual mass flow important.
  • DE 19724659 AI discloses a mass flow sensor device comprising a sensor element.
  • the sensor element is arranged and integrated on a separate chip.
  • an off ⁇ evaluation electronics which is formed separately, but is electrically coupled with the sensor unit.
  • Modern air mass meters for example, built in microsystem (MEMS) technology are very fast and detect almost every change in the air mass flow. In addition, they can be between in Air intake manifold to the internal combustion engine flowing air and from the internal combustion engine back flowing air. Also pulsations in the air intake pipe, which are caused by the cyclical operation of reciprocating internal combustion engines, are detected by high-speed air mass meters and converted by the sensor element into a signal.
  • MEMS microsystem
  • the invention has for its object to provide a fast air ⁇ mass meter, which has the lowest possible error in the processing of the signal.
  • the invention has for its object to provide a method for processing signals of an air mass meter, in which the lowest possible processing error occurs.
  • the electronic circuit initially has an element for order ⁇ conversion of the non-linear signal characteristic from the sensor element in a corrective to a, at least in sections not ⁇ linear signal characteristic error in the formation of the mean value are used for the air mass flow in the filter element is substantially reduced.
  • the first Temperatursen ⁇ sorelement, the second temperature sensing element and the heating element have a different ⁇ generally response.
  • the first temperature sensor element is cooled only by the air mass flow and not heated by the heating element.
  • the second temperature sensor element is first heated by the heating element and then cooled further with increasing air mass flow.
  • the heating element is exclusively cooled by the air mass flow. All these components also have Ferti ⁇ tolerances. In the conversion of the non-linear signal characteristic from the sensor element into a cor- rectifying, at least partially non-linear signal ⁇ characteristic to be considered. The corrective, at least partially non-linear signal characteristic can therefore be adjusted with high precision for the individual air mass meter due to a series of specific information.
  • This specific information can be stored in an electronic memory of the air mass meter.
  • the specific information includes the response of the first temperature sensor, the second temperature sensor and the heating element and the manufacturing tolerances of these components.
  • the filter element performs the integration for averaging in the air mass space and not in the signal space.
  • a conversion element for converting the linear signal characteristic into a correcting, at least partially non-linear signal characteristic By means of a conversion element for converting the linear signal characteristic into a correcting, at least partially non-linear signal characteristic, it is possible to effectively avoid faulty signal processing, which occurs especially at low mass flows.
  • the relay element for forwarding the signals detected by the sensor element and processed by the element for the conversion the filter element and the conversion element to provide loading ists is accurate signals representative of the mass air flow in the air ⁇ mass meter. These highly accurate signals are sent to the engine controller.
  • a particularly accurate air mass meter is disclosed, with the aid of which the combustion of fuel in the cylinders of an internal combustion engine can be optimally adjusted. This is a contribution to the optimal use of fossil fuel reserves and to protect the environment. The same applies to the method for processing signals of an air mass meter.
  • the sensor element and the electronic circuit are formed on a single semiconductor element. This has the advantage that the component can be constructed inexpensively and very error-free.
  • the sensor element and the electronic circuit can be produced in microsystem technology. It is advantageous if the sensor element has a first Tempe ⁇ ratursensorelement and a second temperature sensor element. With the first and the second temperature sensor element, the air mass flow can be determined simply and accurately in the so-called differential temperature method. For this purpose, it is advantageous if it has if it has if it has if it has if it has if it has if it has if it has if it has if it has if it has if it has if it has if it has if it has if it has if it has if it has if it has if it has if it has if it has if it has if it has if it has if it has if it has if it has if it has if it has if it has if it has if it has if it has a
  • FIG. 1 shows an internal combustion engine
  • FIG. 2 shows an air mass meter according to the invention with a
  • FIG. 3 shows schematically the components of the invention
  • Air mass meter Figure 4a the pulsating in the air intake air mass flow in
  • FIG. 4b shows the non-linear signal characteristic of the sensor element
  • FIG. 4c shows a non-linearized time-dependent signal
  • FIG. 5a shows the air mass flow pulsing in the air intake pipe in FIG.
  • Figure 5b shows the nonlinear signal characteristic of the sensor element
  • FIG. 6a shows an example of a faulty signal
  • 6b shows the converted signal of the sensor element in From ⁇ dependence of the real air mass flow
  • Figure 7 a sensor element of an air mass meter.
  • FIG. 1 shows an internal combustion engine 11.
  • This internal combustion engine 11 may be both an internal combustion engine 11 driven by gasoline and an internal combustion engine 11 driven by diesel fuel. It is also conceivable that the internal combustion engine 11 is driven by gas.
  • air filter 15 By the air filter 15 outside air is sucked into the air intake pipe 14 and transported to the engine 11.
  • Ver ⁇ incineration of the fuel it is necessary to determine the transported in the air intake pipe 14 air mass flow Q exactly. This determination of air mass flow Q will be within the air mass senmesser 6, which passes its signal S to the engine controller. 8
  • the engine controller 8 controls depending on the
  • Air mass meter 6 supplied signal S for example, the injection pump 13 and the injectors 12.
  • each cylinder 16 of the engine 11 is supplied in accordance with the intake air mass Q a precisely metered amount of fuel through the injectors 12.
  • Air mass flow Q toward the cylinders 16 allows optimal combustion of the supplied via the injection pump 13 and the injectors 12 to the engine 11 fuel. This allows optimum efficiency of the internal combustion engine 11 and thus an economical consumption of fuels and a relief of the environment.
  • the known internal combustion engines 11 are cyclical internal combustion engines in which the cylinders 16 are alternately filled with fresh air, followed by combustion of the injected fuel, and whereupon the exhaust gases are removed from the cylinders 16, the mass air flow Q is made to the Internal combustion engine is not continuous, but it is coupled with a so-called pulsation.
  • the pulsations arise because each cylinder 16 per combustion process, only a certain discrete amount of fresh air is supplied. After the supply of the fresh air into the cylinder 16, the air inlet valve of the cylinder 16 is closed, and the air mass flow Q is abruptly interrupted. These pulsations are evident in the signal S of a fast and modern air-mass meter 6.
  • Mo ⁇ gating 8 can not handle a rapidly pulsating signal S MAF. 6
  • modern micromechanical air mass sensors 6 absorb this pulsation almost completely and convert it into an output signal S.
  • the engine control unit 8 only the average air mass flow Q is of interest, and only this value can process the engine control 8, for example, to control the injection pump 13 and the injectors 12 accordingly.
  • modern engine control units are controlled by a signal which consists of digi ⁇ tal single pulses, the time interval between the digital single pulses is considered as a measure of the air mass flow Q. In this time difference measurement, the time between the edge of a start signal and the edge of a stop signal is determined with a certain resolution. Whether the rising or falling edge is used depends on the electronics used in the motor control.
  • Both the pulsation in the air mass flow Q and the transmission of the time signal ⁇ S to the motor controller 8 include sources of error, both electronic noise signals as well as the characteristics of modern micromechanical air knives 6 are their own.
  • the first temperature sensor element is cooled only by the air mass flow and not heated by the heating element.
  • the second temperature sensor element is first of Heating element heated and then cooled with increasing air mass flow more and more.
  • the heating element is exclusively cooled by the air mass flow. All these components also have manufacturing tolerances.
  • These error sources degrade the resolution in the time difference measurement during the transmission of the timing signal ⁇ S to the motor controller 8.
  • Figure 2 shows an air mass meter 6 with a sensor element 1 for detecting an air mass flow Q and for generating a signal S.
  • the sensor element is a fast sensor element, which is built, for example, in microsystem (MEMS) technology
  • MEMS microsystem
  • the air mass meter 6 has an electronic circuit 7 for processing the signal from the sensor element 1.
  • the sensor element 1 shows a non-linear signal characteristic.
  • the signal characteristic 9 corresponds to all signals S which can be generated by the sensor element 1 to the corresponding air mass flows Q.
  • the non-linear relationship between the air mass flow Q and the signals S sensor element 1 is shown and explained later in Figure 3 in the Q-S diagram of the sensor element 1.
  • the electronic circuit 7 shown in FIG. 2 initially contains an element 2 for converting the non-linear signal characteristic 9 from the sensor element 1 into a correcting, at least partially non-linear signal characteristic 10.
  • the corrective, at least partially non-linear signal S thus generated is then applied to a filter element 3 passed.
  • This filter element 3 is integrated via the signal S received by the element 2 for conversion of the nonlinear signal characteristic 9. This integration takes place over the time t.
  • the function of the integral S (t) by dt in the filter element 3 (j "S (t) dt) formed.
  • the signal S is in this case the same as the air mass senstrom Q is a dependent function of the time t.
  • the integral IS ⁇ t ) dt corresponds to the mean air mass flow Q, with the pulsations now being filtered out by the filter element 3.
  • the signal S thus generated by the filter element 3 is then converted 4 element for converting the now integrated correcting, at least partially non-linear signal characteristic 10 in a non-linear signal characteristic 9 fed.
  • the now completely nonlinear signal is then forwarded to a relay element 5 for passing on the signal S detected by the sensor element 1 and processed by the element 2 for conversion, the filter element 3 and the conversion element 4. From the relay element 5, a digital time signal A S is sent to the motor controller 8.
  • the time interval between two individual pulses of this digital time signal ⁇ S corresponds to the measured by the air mass meter 6 with the sensor element 1 and further processed with the electronic circuit 7, in particular averaged, signal value S for the air mass flow Q.
  • the air mass meter 6 shown in Figure 2 can with the inventive Method for processing signals to be operated.
  • the air mass meter 6 has a sensor element 1 for detecting an air mass flow Q and for generating a signal S.
  • the air mass meter 6 has an electronic circuit 7 for processing the signal S from the sensor element 1, wherein the sensor element 1 generates a nonlinear signal characteristic 9.
  • ⁇ process according to the transformation of the non-linear signal characteristic 9 of the sensor element 1 in a cor- yawing, at least partially non-linear signal characteristic ⁇ line 10. Then, first takes place the filtering takes place of the correcting at least partially non-linear signal characteristic curve 10, for example, in an integration over the Function j " S (t) dt, whereby the mean air mass flow Q is determined, followed by a conversion of the filtered correcting, at least partially nonlinear signal characteristic 10 into a non ⁇ linear signal characteristic 9, after which a transfer of the data detected by the sensor element 1 and by the Element 2 for conversion, the filter element 3 and the conversion element 4 processed signals.
  • FIG. 3 shows schematically the components of the air mass meter 6 according to the invention with their functions.
  • the sensor element 1 can be seen, which is usually constructed in MEMS technology (microsystem technology) and detects the air mass flow Q.
  • the sensor element 1 and the electronic circuit 7 are formed on a single semiconductor element.
  • the fast sensor element 1 generates a non-linear signal characteristic ⁇ 9, in the corresponding air mass flow Q - is shown - Signal S diagram.
  • This non-linear signal characteristic 9 is electronically converted by the element 2 for conversion to a corrected, at least partially non-linear signal ⁇ characteristic, wherein the signal space produced by the sensor element 1 is left and a transition is made back to the real air mass flow space.
  • Signal S shows a corrective, at least partially non-linear characteristic curve.
  • the filter element On this corrective, at least partially non-linear characteristic, the filter element
  • the relay element 5 Based on this non-linear signal characteristic 9, the relay element 5 generates an electronic time signal A S, which is supplied to the motor control 8. In addition to the electronic
  • Transfer element 5 is the time signal ⁇ S to be detected, which is generated by the relay element 5.
  • the upper function shows the ideal signal characteristic from which a sharp time signal AES could be transmitted to the engine control unit 8.
  • the time signals are always electronically noisy, as shown in the lower time signal A s. Due to the electronic noise the time signal ⁇ S becomes an error of + - ⁇ , which is passed to the engine controller 8 added.
  • the conversion of the integrated correcting, at least partially nonlinear signal characteristic 10 into a non-linear signal characteristic 9 with the element 4 for generating the nonlinear signal characteristic 9 took place. The problem of error propagation in the individual signals S and Time signal ⁇ S will be explained later.
  • FIG. 4 a shows the air mass flow Q pulsating in the air intake pipe 14 as a function of the time t.
  • an ideal sinusoidal pulsation is shown.
  • the real air mass flow Q thus moves here in the air intake pipe 14 between a maximum value Q ma x and a minimum value 0, which occurs when all the air inlet valves of Ver ⁇ combustion engine 11 are closed, and the air mass flow Q in the air intake pipe 14 comes to a standstill.
  • the transition from the nonlinear signal characteristic 9 to the linear signal characteristic 10a can be adapted for each air mass flow Q lying in the measuring range of the sensor element 1 and any pipe cross section lying in the measuring range, according to the requirements of the users of the air mass meter using a characteristic diagram.
  • This map can be stored, for example, in an electronic memory in the element 2 for conversion. If, after the linearization of the nonlinear signal S by means of the filter element 3, an electronic integration j " S (t) dt is carried out via the signal function S (t), no deviation of the mean value from the average air mass flow Q present in the real air mass space is obtained. Der by the nonlinear sensor characteristic 9 of the Sensor element 1 resulting integration error was eliminated by the linearization of the signal with the element 2 for conversion.
  • the measured value for the mean air mass flow Q thus determined must be forwarded to the engine control unit 8 in the form of a time signal. Since the electronic noise in the time signal is clearly noticeable in the case of small signal values for the air mass flow Q, the conversion of the linear signal characteristic according to FIG. 5c after the implementation of the integration by the filter element 3 by the element 4 for generating a nonlinear signal characteristic 10 is necessary. These again non-linear signal characteristic are particularly well suited to pass a time-dependent signal, which is proportional to the air mass flow Q in the air intake pipe 14, to the motor controller 8, without generating a large error ⁇ in the time signal AS.
  • a sensor element 1 having, for example, a first and a second temperature sensor, between which a heating element is arranged, have the first temperature sensor element, the second Temperature sensor element and the heating element on a generally different response.
  • the first temperature sensor element is for example only cooled by the air mass flow ⁇ and not heated by the heating element.
  • the second temperature sensor element is first heated by the heating element and then cooled further with increasing air mass flow.
  • the heating element is exclusively cooled by the air mass flow. All these components also have Ferti ⁇ tolerances. These sources of error in turn degrade the resolution in the time difference measurement during the transmission of the time signal ⁇ S to the motor controller 8.
  • FIG. 6 a shows an example of a faulty signal, which can arise due to the component tolerances and the different response times of the temperature sensor elements 18, 19 and of the heating element 20.
  • Q stands in the diagram shown here for the
  • Air mass flow The error, which arises according to the component tolerances and different response times, is output in percent.
  • the second tempera ⁇ tursensorelement 19 is cooled only slightly by the low air mass flow Q and is thus disproportionately heated by the heating element 20.
  • the error continues to be corrected, wherein, for example, with an air mass flow Q of one hundred relative units, the error just described is completely compensated.
  • the higher air mass flow Q starts to dominate at the second temperature sensor element 19 and this cool überpropor ⁇ tion strong, whereupon a negative error occurs, which builds up to about four hundred relative units of the air mass flow Q.
  • the errors caused in the air mass meter by the component tolerances and different response times overlap, which leads to an approximation to the optimum, error-free range for the air mass flow.
  • FIG. 6b shows the converted signal of the sensor element 1 as a function of the actual air mass flow Q.
  • the dashed line 10a shows the nonlinear sensor characteristic curve 9 after its simple linearization.
  • the curve shows the reference numeral 10, the correcting, at least from ⁇ section-wise non-linear signal response 10 resulting from the nonlinear sensor characteristic 9 was generated taking into account the component tolerances and the different response times.
  • FIG. 7 shows a sensor element 1 of an air flow sensor 6.
  • the sensor element 1 includes a substrate 17, on which a first temperature-sensor element 18 and a second temperature sensor element are arranged ⁇ 19th Between the first temperature sensor element 18 and the second temperature sensor element 19, a heater 20 is arranged on the substrate 17. The direction of the air mass flow Q is indicated by the arrow.

Landscapes

  • Physics & Mathematics (AREA)
  • Fluid Mechanics (AREA)
  • General Physics & Mathematics (AREA)
  • Measuring Volume Flow (AREA)
  • Combined Controls Of Internal Combustion Engines (AREA)

Abstract

The invention relates to an air mass flow meter, comprising a sensor element for detecting an air mass flow and for producing a signal and comprising an electronic circuit for processing the signal from the sensor element, wherein the sensor element produces a non-linear signal characteristic. In order to specify a rapid air mass flow meter that has as small an error as possible in the processing of the signal, the electronic circuit (7) first has an element (2) for converting the non-linear signal characteristic (9) from the sensor element (1) into a correcting signal characteristic (10) that is non-linear at least in some segments, and the circuit then has a filter element (3), a conversion element (4) for converting the correcting signal characteristic (10) which is non-linear at least in some segments into a non-linear signal characteristic (9), and a relay element (5) for relaying the signals (S) detected by the sensor element (1) and processed by the linearization element (2), the filter element (3), and the conversion element (4).

Description

Beschreibung Luftmassenmesser Die Erfindung betrifft einen Luftmassenmesser mit einem Sensorelement zur Erfassung eines Luftmassenstroms und zur Er¬ zeugung eines Signals und mit einer elektronischen Schaltung zur Verarbeitung des Signals vom Sensorelement, wobei das Sensor¬ element eine nichtlineare Signalkennlinie erzeugt. Weiterhin betrifft die Erfindung ein Verfahren zur Verarbeitung vonDescription air mass meter The invention relates to an air-mass meter with a sensor element for detecting an air mass flow and He ¬ generating a signal and with an electronic circuit for processing the signal from the sensor element, the sensor ¬ element produces a non-linear signal characteristic. Furthermore, the invention relates to a method for processing
Signalen eines Luftmassenmessers, wobei der Luftmassenmesser ein Sensorelement zur Erfassung eines Luftmassenstroms und zur Erzeugung eines Signals aufweist und eine elektronische Signals of an air mass meter, wherein the air mass meter has a sensor element for detecting an air mass flow and for generating a signal and an electronic
Schaltung zur Verarbeitung des Signals vom Sensorelement auf- weist, wobei das Sensorelement eine nichtlineare Signalkennlinie erzeugt . Circuit for processing the signal from the sensor element up, wherein the sensor element generates a non-linear signal characteristic.
Luftmassenmesser sind geeignet zum Erfassen eines Massenstroms eines Fluids (Luftmassenstroms) in einem Strömungskanal. Ein derartiger Strömungskanal kann beispielsweise ein Luftansaug¬ rohr einer Brennkraftmaschine sein. Abhängig von dem durch den Luftmassenmesser erfassten Massenstrom können sowohl Diagnosen beispielsweise des Betriebes der Brennkraftmaschine durchge¬ führt werden als auch eine Steuerung der Brennkraftmaschine erfolgen. Zu diesen Zwecken ist ein auch unter unterschiedlichen Betriebsbedingungen zuverlässiges und möglichst präzises Er¬ fassen des tatsächlichen Massenstroms wichtig. Air mass meters are suitable for detecting a mass flow of a fluid (air mass flow) in a flow channel. Such a flow channel can be for example an air intake pipe ¬ an internal combustion engine. Depending on the value detected by the air mass meter mass flow both diagnoses, for example, the operation of the internal combustion engine Runaway ¬ leads can be also be performed as a control of the internal combustion engine. For these purposes, also under different operating conditions reliable and accurate as possible, he ¬ grasp the actual mass flow important.
DE 19724659 AI offenbart eine Massenstromsensorvorrichtung, die ein Sensorelement umfasst. Das Sensorelement ist auf einem eigenen Chip angeordnet und integriert. Ferner ist eine Aus¬ werteelektronik offenbart, die separat ausgebildet ist, aber mit der Sensoreinheit elektrisch gekoppelt ist. Moderne, zum Beispiel in Mikrosystem (MEMS ) -Technik gebaute Luftmassenmesser sind sehr schnell und erfassen nahezu jede Änderung im Luftmassenstrom. Zudem können sie zwischen im Luftansaugrohr zur Brennkraftmaschine strömender Luft und von der Brennkraftmaschine zurück strömender Luft unterscheiden. Auch Pulsationen im Luftansaugrohr, die durch die zyklische Arbeitsweise von Kolbenbrennkraftmaschinen entstehen, werden von schnellen Luftmassenmessern erfasst und vom Sensorelement in ein Signal umgewandelt. Gerade diese Pulsationen können jedoch zur erheblichen Verfälschung des Messwertes für den mittleren Luftmassenstrom führen. Der Erfindung liegt die Aufgabe zugrunde, einen schnellen Luft¬ massenmesser anzugeben, der einen möglichst geringen Fehler bei der Verarbeitung des Signals aufweist. Darüber hinaus liegt der Erfindung die Aufgabe zugrunde, ein Verfahren zur Verarbeitung von Signalen eines Luftmassenmessers anzugeben, bei dem ein möglichst geringer Verarbeitungsfehler auftritt. DE 19724659 AI discloses a mass flow sensor device comprising a sensor element. The sensor element is arranged and integrated on a separate chip. Further, there is disclosed an off ¬ evaluation electronics, which is formed separately, but is electrically coupled with the sensor unit. Modern air mass meters, for example, built in microsystem (MEMS) technology are very fast and detect almost every change in the air mass flow. In addition, they can be between in Air intake manifold to the internal combustion engine flowing air and from the internal combustion engine back flowing air. Also pulsations in the air intake pipe, which are caused by the cyclical operation of reciprocating internal combustion engines, are detected by high-speed air mass meters and converted by the sensor element into a signal. However, it is precisely these pulsations that can lead to a significant falsification of the measured value for the average air mass flow. The invention has for its object to provide a fast air ¬ mass meter, which has the lowest possible error in the processing of the signal. In addition, the invention has for its object to provide a method for processing signals of an air mass meter, in which the lowest possible processing error occurs.
Die Aufgaben werden durch die Merkmale der unabhängigen Ansprüche gelöst . Da die elektronische Schaltung zunächst ein Element zur Um¬ wandlung der nichtlinearen Signalkennlinie vom Sensorelement in eine in eine korrigierende, zumindest abschnittsweise nicht¬ lineare Signalkennlinie aufweist, werden Fehler bei der Bildung des Mittelwertes für den Luftmassenstrom in dem Filterelement wesentlich reduziert. Bei einem Sensorelement, das einen ersten und einen zweiten Temperatursensor aufweist, zwischen denen ein Heizelement angeordnet ist, weisen das erste Temperatursen¬ sorelement, das zweite Temperatursensorelement und das Heiz¬ element ein in der Regel unterschiedliches Ansprechverhalten auf. Beispielsweise wird das erste Temperatursensorelement nur vom Luftmassenstrom gekühlt und nicht vom Heizelement erwärmt. Das zweite Temperatursensorelement hingegen wird zunächst vom Heizelement erwärmt und dann mit zunehmendem Luftmassenstrom immer weiter abgekühlt. Das Heizelement wird vom Luftmassenstrom ausschließlich gekühlt. Alle diese Bauteile weisen zudem Ferti¬ gungstoleranzen auf. Diese Aspekte können bei der Umwandlung der nichtlinearen Signalkennlinie vom Sensorelement in eine kor- rigierende, zumindest abschnittsweise nichtlineare Signal¬ kennlinie berücksichtigt werden. Die korrigierende, zumindest abschnittsweise nichtlineare Signalkennlinie kann also für den einzelnen Luftmassenmesser aufgrund einer Reihe von spezifischen Informationen hochgenau angepasst werden. Diese spezifischen Informationen können in einem elektronischen Speicher des Luftmassenmessers abgelegt sein. Zu den spezifischen Informationen gehören das Ansprechverhalten des ersten Temperatursensors , des zweiten Temperatursensors und des Heizelementes sowie die Fertigungstoleranzen dieser Bauteile. Das Filterelement führt die Integration zur Mittelwertbildung im Luftmassenraum aus und nicht im Signalraum. Durch ein Umwandlungselement zur Umwandlung der linearen Signalkennlinie in eine korrigierende, zumindest abschnittsweise nichtlineare Signalkennlinie lassen sich feh- lerhafte Signalweiterverarbeitungen, die besonders bei geringen Massenströmen auftreten, effektiv vermeiden. Die vom Weitergabeelement zur Weitergabe der vom Sensorelement erfassten und durch das Element zur Umwandlung, das Filterelement und das Umwandlungselement verarbeiteten Signale, stellen damit be- sonders genaue Signale dar, die den Luftmassenstrom im Luft¬ massenmesser abbilden. Diese hochgenauen Signale werden an die Motorsteuerung gesendet. Damit ist ein besonders genauer Luftmassenmesser offenbart, mit dessen Hilfe die Verbrennung von Kraftstoff in den Zylindern einer Brennkraftmaschine optimal eingestellt werden kann. Dies ist ein Beitrag zur optimalen Nutzung von fossilen Brennstoffreserven und zur Schonung der Umwelt. Auch für das Verfahren zur Verarbeitung von Signalen eines Luftmassenmessers gilt das soeben Gesagte. Bei einer Weiterbildung sind das Sensorelement und die elektronische Schaltung auf einem einzigen Halbleiterelement ausgebildet . Dies hat den Vorteil, dass das Bauteil kostengünstig und besonders fehlerfrei aufgebaut werden kann. Dazu kann das Sensorelement und die elektronische Schaltung in Mikrosystem- Technologie hergestellt sein. Es ist vorteilhaft, wenn das Sensorelement ein erstes Tempe¬ ratursensorelement und ein zweites Temperatursensorelement aufweist. Mit dem ersten und dem zweiten Temperatursensorelement kann der Luftmassenstorm im sogenannten Differenztemperatur- verfahren einfach und genau bestimmt werden. Dazu ist es vorteilhaft, wenn es ein Heizelement aufweist, das zwischen dem ersten und dem zweiten Temperatursensorelement angeordnet ist. The objects are achieved by the features of the independent claims. Since the electronic circuit initially has an element for order ¬ conversion of the non-linear signal characteristic from the sensor element in a corrective to a, at least in sections not ¬ linear signal characteristic error in the formation of the mean value are used for the air mass flow in the filter element is substantially reduced. In a sensor element having a first and a second temperature sensor, between which a heating element is arranged, the first Temperatursen ¬ sorelement, the second temperature sensing element and the heating element have a different ¬ generally response. For example, the first temperature sensor element is cooled only by the air mass flow and not heated by the heating element. The second temperature sensor element, however, is first heated by the heating element and then cooled further with increasing air mass flow. The heating element is exclusively cooled by the air mass flow. All these components also have Ferti ¬ tolerances. In the conversion of the non-linear signal characteristic from the sensor element into a cor- rectifying, at least partially non-linear signal ¬ characteristic to be considered. The corrective, at least partially non-linear signal characteristic can therefore be adjusted with high precision for the individual air mass meter due to a series of specific information. This specific information can be stored in an electronic memory of the air mass meter. The specific information includes the response of the first temperature sensor, the second temperature sensor and the heating element and the manufacturing tolerances of these components. The filter element performs the integration for averaging in the air mass space and not in the signal space. By means of a conversion element for converting the linear signal characteristic into a correcting, at least partially non-linear signal characteristic, it is possible to effectively avoid faulty signal processing, which occurs especially at low mass flows. By the relay element for forwarding the signals detected by the sensor element and processed by the element for the conversion, the filter element and the conversion element to provide loading Sonders is accurate signals representative of the mass air flow in the air ¬ mass meter. These highly accurate signals are sent to the engine controller. Thus, a particularly accurate air mass meter is disclosed, with the aid of which the combustion of fuel in the cylinders of an internal combustion engine can be optimally adjusted. This is a contribution to the optimal use of fossil fuel reserves and to protect the environment. The same applies to the method for processing signals of an air mass meter. In a development, the sensor element and the electronic circuit are formed on a single semiconductor element. This has the advantage that the component can be constructed inexpensively and very error-free. For this purpose, the sensor element and the electronic circuit can be produced in microsystem technology. It is advantageous if the sensor element has a first Tempe ¬ ratursensorelement and a second temperature sensor element. With the first and the second temperature sensor element, the air mass flow can be determined simply and accurately in the so-called differential temperature method. For this purpose, it is advantageous if it has a heating element which is arranged between the first and the second temperature sensor element.
Die Erfindung wird anhand der folgenden Figuren näher erläutert. Es zeigen: The invention will be explained in more detail with reference to the following figures. Show it:
Figur 1 einen Verbrennungsmotor, FIG. 1 shows an internal combustion engine,
Figur 2 einen erfindungsgemäßen Luftmassenmesser mit einem 2 shows an air mass meter according to the invention with a
Sensorelement,  Sensor element,
Figur 3 schematisch die Bestandteile des erfindungsgemäßen Figure 3 shows schematically the components of the invention
Luftmassenmessers , Figur 4a den im Luftansaugrohr pulsierende Luftmassenstrom in  Air mass meter, Figure 4a the pulsating in the air intake air mass flow in
Abhängigkeit von der Zeit,  Dependence on time,
Figur 4b die nichtlineare Signalkennlinie des Sensorelementes, Figur 4c ein nicht linearisiertes zeitabhängiges Signal, 4b shows the non-linear signal characteristic of the sensor element, FIG. 4c shows a non-linearized time-dependent signal,
Figur 5a den im Luftansaugrohr pulsierende Luftmassenstrom in FIG. 5a shows the air mass flow pulsing in the air intake pipe in FIG
Abhängigkeit von der Zeit, Figur 5b die nichtlineare Signalkennlinie des Sensorelementes,  Dependence on time, Figure 5b shows the nonlinear signal characteristic of the sensor element,
Figur 5c die linearisierte Signalkennlinie des Sensorele¬ mentes, Figur 5d ein linearisiertes zeitabhängiges Signal, 5c shows the linearized signal characteristic of the Sensorele ¬ mentes, Figure 5d a linearized time-dependent signal,
Figur 6a ein Beispiel für ein fehlerhaftes Signal, Figur 6b das umgewandelte Signal des Sensorelementes in Ab¬ hängigkeit vom realen Luftmassenstrom, Figur 7 ein Sensorelement eines Luftmassenmessers. FIG. 6a shows an example of a faulty signal, 6b shows the converted signal of the sensor element in From ¬ dependence of the real air mass flow, Figure 7, a sensor element of an air mass meter.
Figur 1 zeigt einen Verbrennungsmotor 11. Bei diesem Verbrennungsmotor 11 kann es sich sowohl um einen mit Benzin angetriebenen Verbrennungsmotor 11 als auch um einen mit Diesel- kraftstoff angetriebenen Verbrennungsmotor 11 handeln. Denkbar ist auch, dass der Verbrennungsmotor 11 mit Gas angetrieben wird. Am Verbrennungsmotor 11 ist ein Ansaugrohr 14 zu erkennen, das mit einem Luftfilter 15 verbunden ist. Durch den Luftfilter 15 wird Außenluft in das Luftansaugrohr 14 gesaugt und zu dem Verbrennungsmotor 11 transportiert. Für eine optimale Ver¬ brennung des Kraftstoffes ist es notwendig, den im Luftansaugrohr 14 transportierten Luftmassenstrom Q genau zu bestimmen. Diese Bestimmung des Luftmassenstromes Q erfolgt mit dem Luftmas¬ senmesser 6, der sein Signal S an die Motorsteuerung 8 weitergibt. Die Motorsteuerung 8 steuert in Abhängigkeit von dem vomFIG. 1 shows an internal combustion engine 11. This internal combustion engine 11 may be both an internal combustion engine 11 driven by gasoline and an internal combustion engine 11 driven by diesel fuel. It is also conceivable that the internal combustion engine 11 is driven by gas. On the internal combustion engine 11, an intake pipe 14 can be seen, which is connected to an air filter 15. By the air filter 15 outside air is sucked into the air intake pipe 14 and transported to the engine 11. For optimal Ver ¬ incineration of the fuel it is necessary to determine the transported in the air intake pipe 14 air mass flow Q exactly. This determination of air mass flow Q will be within the air mass senmesser 6, which passes its signal S to the engine controller. 8 The engine controller 8 controls depending on the
Luftmassenmesser 6 gelieferten Signal S zum Beispiel die Einspritzpumpe 13 und die Einspritzdüsen 12. Auf diese Art und Weise wird jedem Zylinder 16 des Verbrennungsmotors 11 entsprechend der angesaugten Luftmasse Q eine genau dosierte KraftStoffmenge über die Einspritzdüsen 12 zugeführt. Die genaue Kenntnis desAir mass meter 6 supplied signal S, for example, the injection pump 13 and the injectors 12. In this way, each cylinder 16 of the engine 11 is supplied in accordance with the intake air mass Q a precisely metered amount of fuel through the injectors 12. The exact knowledge of the
Luftmassenstromes Q hin zu den Zylindern 16 ermöglicht eine optimale Verbrennung des über die Einspritzpumpe 13 und die Einspritzdüsen 12 zu dem Verbrennungsmotor 11 zugeführten Kraftstoffes. Dies ermöglicht einen optimalen Wirkungsgrad des Verbrennungsmotors 11 und damit einen sparsamen Verbrauch von Kraftstoffen und eine Entlastung der Umwelt. Air mass flow Q toward the cylinders 16 allows optimal combustion of the supplied via the injection pump 13 and the injectors 12 to the engine 11 fuel. This allows optimum efficiency of the internal combustion engine 11 and thus an economical consumption of fuels and a relief of the environment.
Da die bekannten Verbrennungsmotoren 11 zyklische Brennkraftmaschinen sind, bei denen die Zylinder 16 abwechselnd mit Frisch- luft befüllt werden, wonach es zur Verbrennung des eingespritzten Kraftstoffes kommt, und woraufhin die Abgase aus den Zylindern 16 entfernt werden, erfolgt der Luftmassenstrom Q hin zu dem Verbrennungsmotor nicht kontinuierlich, sondern er ist mit einer sogenannten Pulsation gekoppelt . Die Pulsationen entstehen, weil jedem Zylinder 16 pro Verbrennungsvorgang nur eine bestimmte diskrete Menge Frischluft zugeführt wird. Nach der Zuführung der Frischluft in den Zylinder 16 wird das Lufteinlassventil des Zylinders 16 geschlossen, und der Luftmassenstrom Q wird abrupt unterbrochen. Diese Pulsationen zeigen sich deutlich im Signal S eines schnellen und modernen Luftmassenmessers 6. Die Mo¬ torsteuerung 8 kann jedoch ein schnell pulsierendes Signal S des Luftmassenmessers 6 nicht verarbeiten. Moderne mikromechanisch aufgebaute Luftmassenmesser 6 nehmen diese Pulsation jedoch fast vollständig auf und wandeln sie in ein Ausgangssignal S um. Für die Motorsteuerung 8 ist lediglich der mittlere Luftmassenstrom Q von Interesse, und auch nur diesen Wert kann die Motorsteuerung 8 verarbeiten, um zum Beispiel die Einspritzpumpe 13 und die Einspritzdüsen 12 entsprechend zu steuern. Zudem werden moderne Motorsteuergeräte mit einem Signal angesteuert, das aus digi¬ talen Einzelpulsen besteht, wobei der zeitliche Abstand zwischen den digitalen Einzelpulsen als Maß für den Luftmassenstrom Q gewertet wird. Bei dieser Zeitdifferenzmessung wird die Zeit zwischen der Flanke eines Startsignals und der Flanke eines Stoppsignals mit einer gewissen Auflösung bestimmt. Ob die steigende oder die fallende Flanke benutzt wird, hängt von der verwendeten Elektronik in der Motorsteuerung ab. Since the known internal combustion engines 11 are cyclical internal combustion engines in which the cylinders 16 are alternately filled with fresh air, followed by combustion of the injected fuel, and whereupon the exhaust gases are removed from the cylinders 16, the mass air flow Q is made to the Internal combustion engine is not continuous, but it is coupled with a so-called pulsation. The pulsations arise because each cylinder 16 per combustion process, only a certain discrete amount of fresh air is supplied. After the supply of the fresh air into the cylinder 16, the air inlet valve of the cylinder 16 is closed, and the air mass flow Q is abruptly interrupted. These pulsations are evident in the signal S of a fast and modern air-mass meter 6. Mo ¬ gating 8 can not handle a rapidly pulsating signal S MAF. 6 However, modern micromechanical air mass sensors 6 absorb this pulsation almost completely and convert it into an output signal S. For the engine control unit 8, only the average air mass flow Q is of interest, and only this value can process the engine control 8, for example, to control the injection pump 13 and the injectors 12 accordingly. In addition, modern engine control units are controlled by a signal which consists of digi ¬ tal single pulses, the time interval between the digital single pulses is considered as a measure of the air mass flow Q. In this time difference measurement, the time between the edge of a start signal and the edge of a stop signal is determined with a certain resolution. Whether the rising or falling edge is used depends on the electronics used in the motor control.
Sowohl die Pulsation im Luftmassenstrom Q als auch die Übertragung des Zeitsignals ÄS an die Motorsteuerung 8 beinhalten Fehlerquellen, sowohl aus elektronischen Rauschsignalen als auch aus den Kennlinien, die modernen mikromechanischen Luftmas- senmessern 6 zu eigen sind. Bei einem Sensorelement das einen ersten und einen zweiten Temperatursensor aufweist, zwischen denen ein Heizelement angeordnet ist, weisen das erste Tempe¬ ratursensorelement, das zweite Temperatursensorelement und das Heizelement ein in der Regel unterschiedliches Ansprechverhalten auf. Beispielsweise wird das erste Temperatursensorelement nur vom Luftmassenstrom gekühlt und nicht vom Heizelement erwärmt. Das zweite Temperatursensorelement hingegen wird zunächst vom Heizelement erwärmt und dann mit zunehmendem Luftmassenstrom immer weiter abgekühlt. Das Heizelement wird vom Luftmassenstrom ausschließlich gekühlt. Alle diese Bauteile weisen zudem Fertigungstoleranzen auf. Diese Fehlerquellen verschlechtern zum Beispiel die Auflösung bei der Zeitdifferenzmessung während der Übertragung des Zeitsignals ÄS an die Motorsteuerung 8. Both the pulsation in the air mass flow Q and the transmission of the time signal ÄS to the motor controller 8 include sources of error, both electronic noise signals as well as the characteristics of modern micromechanical air knives 6 are their own. In a sensor element having a first and a second temperature sensor, between which a heating element is arranged, the first Tempe ¬ ratursensorelement, the second temperature sensor element and the heating element on a generally different response. For example, the first temperature sensor element is cooled only by the air mass flow and not heated by the heating element. The second temperature sensor element, however, is first of Heating element heated and then cooled with increasing air mass flow more and more. The heating element is exclusively cooled by the air mass flow. All these components also have manufacturing tolerances. These error sources, for example, degrade the resolution in the time difference measurement during the transmission of the timing signal ÄS to the motor controller 8.
Um dieser Problematik zu begegnen zeigt Figur 2 einen Luftmassenmesser 6 mit einem Sensorelement 1 zur Erfassung eines Luftmassenstromes Q und zur Erzeugung eines Signals S. Bei dem Sensorelement handelt es sich um ein schnelles Sensorelement, das zum Beispiel in Mikrosystem (MEMS ) -Technik gebaut ist. Der Luftmassenmesser 6 weist eine elektronische Schaltung 7 zur Verarbeitung des Signals vom Sensorelement 1 auf. Das Sensorelement 1 zeigt eine nichtlineare Signalkennlinie. Die Signalkennlinie 9 entspricht allen Signalen S, die zu den entsprechenden Luftmassenströmen Q vom Sensorelement 1 erzeugt werden können. Der nichtlineare Zusammenhang zwischen dem Luftmassenstrom Q und den Signalen S Sensorelements 1 wird später in Figur 3 in dem Q-S-Diagramm des Sensorelementes 1 dargestellt und erklärt. To counter this problem, Figure 2 shows an air mass meter 6 with a sensor element 1 for detecting an air mass flow Q and for generating a signal S. The sensor element is a fast sensor element, which is built, for example, in microsystem (MEMS) technology , The air mass meter 6 has an electronic circuit 7 for processing the signal from the sensor element 1. The sensor element 1 shows a non-linear signal characteristic. The signal characteristic 9 corresponds to all signals S which can be generated by the sensor element 1 to the corresponding air mass flows Q. The non-linear relationship between the air mass flow Q and the signals S sensor element 1 is shown and explained later in Figure 3 in the Q-S diagram of the sensor element 1.
Die in Figur 2 gezeigte elektronische Schaltung 7 beinhaltet zunächst ein Element 2 zur Umwandlung der nichtlinearen Signalkennlinie 9 vom Sensorelement 1 in eine korrigierende, zu- mindest abschnittsweise nichtlineare Signalkennlinie 10. Das so erzeugte korrigierende, zumindest abschnittsweise nichtlineare Signal S wird dann an ein Filterelement 3 weitergegeben. Dieses Filterelement 3 integriert über das von dem Element 2 zur Um¬ wandlung der nichtlinearen Signalkennlinie 9 empfangene Signal S. Diese Integration erfolgt über die Zeit t. Damit wird im Filterelement 3 die Funktion Integral S(t) nach dt (j" S (t)dt ) gebildet. Das Signal S ist hierbei genauso wie der Luftmas¬ senstrom Q eine von der Zeit t abhängige Funktion. Das Integral I S{t)dt entspricht dem mittleren Luftmassenstrom Q, wobei nun die Pulsationen vom Filterelement 3 herausgefiltert wurden. Das so vom Filterelement 3 erzeugte Signal S wird dann einem Umwand- lungselement 4 zur Umwandlung der nun integrierten korrigierenden, zumindest abschnittsweise nichtlineare Signalkennlinie 10 in eine nichtlineare Signalkennlinie 9 zugeleitet. Das nun wieder vollständig nichtlineare Signal wird dann einem Wei- tergabeelement 5 zur Weitergabe der vom Sensorelement 1 erfassten und durch das Element 2 zur Umwandlung, das Filterelement 3 und das Umwandlungselement 4 verarbeiteten Signal S zugeleitet. Vom Weitergabeelement 5 wird ein digitales Zeitsignal ÄS an die Motorsteuerung 8 gesendet. Der zeitliche Abstand zwischen zwei Einzelpulsen dieses digitalen Zeitsignals ÄS entspricht dann dem vom Luftmassenmesser 6 mit dem Sensorelement 1 gemessenen und mit der elektronischen Schaltung 7 weiterverarbeiteten, insbesondere gemittelten, Signalwertes S für den Luftmassenstrom Q. Der in Figur 2 gezeigte Luftmassenmesser 6 kann mit dem erfindungsgemäßen Verfahren zur Verarbeitung von Signalen betrieben werden. Dabei weist der Luftmassenmesser 6 ein Sensorelement 1 zur Erfassung eines Luftmassenstromes Q und zur Erzeugung eines Signals S auf. Weiterhin weist der Luftmas- senmesser 6 eine elektronische Schaltung 7 zur Verarbeitung des Signals S vom Sensorelement 1 auf, wobei das Sensorelement 1 eine nichtlineare Signalkennlinie 9 erzeugt. Bei dem erfindungs¬ gemäßen Verfahren erfolgt zunächst die Umwandlung der nichtlinearen Signalkennlinie 9 vom Sensorelement 1 in eine korri- gierende, zumindest abschnittsweise nichtlineare Signalkenn¬ linie 10. Dann erfolgt die Filterung der korrigierenden, zumindest abschnittsweise nichtlinearen Signalkennlinie 10 zum Beispiel in einer Integration über die Funktion j" S(t)dt , wobei der mittlere Luftmassenstrom Q ermittelt wird. Dann erfolgt eine Umwandlung der gefilterten korrigierenden, zumindest abschnittsweise nichtlineare Signalkennlinie 10 in eine nicht¬ lineare Signalkennlinie 9, wonach eine Weitergabe der von dem Sensorelement 1 erfassten und durch das Element 2 zur Umwandlung, das Filterelement 3 und das Umwandlungselement 4 verarbeiteten Signale erfolgt. Figur 3 zeigt schematisch die Bestandteile des erfindungsgemäßen Luftmassenmessers 6 mit ihren Funktionen. Zunächst ist das Sensorelement 1 zu erkennen, das in der Regel in MEMS-Technologie (Mikrosystem-Technologie ) aufgebaut ist und den Luftmassenstrom Q erfasst. Das Sensorelement 1 und die elektronische Schaltung 7 sind auf einem einzigen Halbleiterelement ausgebildet. Das schnelle Sensorelement 1 erzeugt eine nichtlineare Signal¬ kennlinie 9, die im dazugehörigen Luftmassenstrom Q - Signal S-Diagramm - dargestellt ist . Diese nichtlineare Signalkennlinie 9 wird vom Element 2 zur Umwandlung elektronisch in eine korrigierenden, zumindest abschnittsweise nichtlineare , Signal¬ kennlinie gewandelt, wobei der von dem Sensorelement 1 erzeugten Signalraum verlassen wird und ein Übergang zurück in den realen Luftmassenstromraum erfolgt. Das neben dem Element 2 zur Um- Wandlung gezeigte Diagramm des Luftmassenstromes Q und desThe electronic circuit 7 shown in FIG. 2 initially contains an element 2 for converting the non-linear signal characteristic 9 from the sensor element 1 into a correcting, at least partially non-linear signal characteristic 10. The corrective, at least partially non-linear signal S thus generated is then applied to a filter element 3 passed. This filter element 3 is integrated via the signal S received by the element 2 for conversion of the nonlinear signal characteristic 9. This integration takes place over the time t. Thus the function of the integral S (t) by dt in the filter element 3 (j "S (t) dt) formed. The signal S is in this case the same as the air mass senstrom Q is a dependent function of the time t. The integral IS {t ) dt corresponds to the mean air mass flow Q, with the pulsations now being filtered out by the filter element 3. The signal S thus generated by the filter element 3 is then converted 4 element for converting the now integrated correcting, at least partially non-linear signal characteristic 10 in a non-linear signal characteristic 9 fed. The now completely nonlinear signal is then forwarded to a relay element 5 for passing on the signal S detected by the sensor element 1 and processed by the element 2 for conversion, the filter element 3 and the conversion element 4. From the relay element 5, a digital time signal A S is sent to the motor controller 8. The time interval between two individual pulses of this digital time signal ÄS then corresponds to the measured by the air mass meter 6 with the sensor element 1 and further processed with the electronic circuit 7, in particular averaged, signal value S for the air mass flow Q. The air mass meter 6 shown in Figure 2 can with the inventive Method for processing signals to be operated. In this case, the air mass meter 6 has a sensor element 1 for detecting an air mass flow Q and for generating a signal S. Furthermore, the air mass meter 6 has an electronic circuit 7 for processing the signal S from the sensor element 1, wherein the sensor element 1 generates a nonlinear signal characteristic 9. In the fiction, ¬ process according to the transformation of the non-linear signal characteristic 9 of the sensor element 1 in a cor- yawing, at least partially non-linear signal characteristic ¬ line 10. Then, first takes place the filtering takes place of the correcting at least partially non-linear signal characteristic curve 10, for example, in an integration over the Function j " S (t) dt, whereby the mean air mass flow Q is determined, followed by a conversion of the filtered correcting, at least partially nonlinear signal characteristic 10 into a non ¬ linear signal characteristic 9, after which a transfer of the data detected by the sensor element 1 and by the Element 2 for conversion, the filter element 3 and the conversion element 4 processed signals. Figure 3 shows schematically the components of the air mass meter 6 according to the invention with their functions. First, the sensor element 1 can be seen, which is usually constructed in MEMS technology (microsystem technology) and detects the air mass flow Q. The sensor element 1 and the electronic circuit 7 are formed on a single semiconductor element. The fast sensor element 1 generates a non-linear signal characteristic ¬ 9, in the corresponding air mass flow Q - is shown - Signal S diagram. This non-linear signal characteristic 9 is electronically converted by the element 2 for conversion to a corrected, at least partially non-linear signal ¬ characteristic, wherein the signal space produced by the sensor element 1 is left and a transition is made back to the real air mass flow space. The diagram of the mass air flow Q and of the air flow shown next to the element 2 for conversion
Signals S zeigt eine korrigierende, zumindest abschnittsweise nichtlineare Kennlinie. Auf dieser korrigierenden, zumindest abschnittsweise nichtlinearen Kennlinie kann das FilterelementSignal S shows a corrective, at least partially non-linear characteristic curve. On this corrective, at least partially non-linear characteristic, the filter element
3 elektronisch integrieren und das Integral j" S(t)dt bilden, womit ein mittlerer Luftmassenstrom Q ermittelt wird und die im Luftansaugrohr 14 vorhandenen Pulsationen heraus gefiltert werden. Durch die korrigierende, zumindest abschnittsweise nichtlineare Signalkennlinie geschieht dies fast völlig feh¬ lerfrei. Nach dem Filterelement 3 ist das Element 4 zur Erzeugung einer nichtlinearen Signalkennlinie 9 zu erkennen. Die nicht¬ lineare Signalkennlinie 9 wird wiederum elektronisch vom Element3 electronically integrated and the integral j "S (t) dt form, whereby a mean air mass flow rate Q is determined and present in the air intake pipe 14 pulsations out are filtered. By correcting, at least partially non-linear signal characteristic, this is done almost entirely FEH ¬ lerfrei. After the filter element 3 can be seen, the element 4 for producing a non-linear signal characteristic. 9 ¬ the non-linear signal characteristic of the element 9 is in turn electronically
4 zur Erzeugung einer nichtlinearen Signalkennlinie 9 erzeugt. Ausgehend von dieser nichtlinearen Signalkennlinie 9 erzeugt das Weitergabeelement 5 ein elektronisches Zeitsignal ÄS, das der Motorsteuerung 8 zugeführt wird. Neben dem elektronischen4 for generating a non-linear signal characteristic 9 generated. Based on this non-linear signal characteristic 9, the relay element 5 generates an electronic time signal A S, which is supplied to the motor control 8. In addition to the electronic
Weitergabeelement 5 ist das Zeitsignal ÄS zu erkennen, das von dem Weitergabeelement 5 erzeugt wird. Die obere Funktion zeigt die ideale Signalkennlinie, aus der ein scharfes Zeitsignal ÄS an die Motorsteuerung 8 übermittelt werden könnte. Leider sind die Zeitsignale in der Realität immer elektronisch verrauscht, was in dem unteren Zeitsignal ÄS dargestellt ist. Durch das elektronische Rauschen wird dem Zeitsignal ÄS ein Fehler von +- ΔΤ hinzugefügt, der an die Motorsteuerung 8 weitergegeben wird. Um diesen Fehler ΔΤ möglichst gering zu halten, erfolgte die Umwandlung der integrierten korrigierenden, zumindest abschnittsweise nichtlineare Signalkennlinie 10 in eine nicht- lineare Signalkennlinie 9 mit dem Element 4 zur Erzeugung der nichtlinearen Signalkennlinie 9. Die Problematik der Fehlerfortpflanzung beim den einzelnen Signalen S und beim Zeitsignal ÄS wird später erläutert. In der Figurenfolge 4 und 5 soll die Problematik näher erläutert werden, die entsteht, wenn schnelle, in MEMS-Technologie ge¬ fertigte, Sensorelemente 1 einen im Luftansaugrohr 14 pulsie¬ renden Luftmassenstrom Q messtechnisch erfassen. In Figur 4a ist der im Luftansaugrohr 14 pulsierende Luftmassenstrom Q in Abhängigkeit von der Zeit t dargestellt. Bei¬ spielhaft ist hier eine ideale sinusförmige Pulsation gezeigt. Der reale Luftmassenstrom Q bewegt sich hier also im Luftansaugrohr 14 zwischen einem Maximalwert Qmax und einem Minimalwert 0, der dann eintritt, wenn alle Lufteinlassventile des Ver¬ brennungsmotors 11 geschlossen sind, und der Luftmassenstrom Q im Luftansaugrohr 14 zum Stillstand kommt . Für die MotorsteuerungTransfer element 5 is the time signal ÄS to be detected, which is generated by the relay element 5. The upper function shows the ideal signal characteristic from which a sharp time signal AES could be transmitted to the engine control unit 8. Unfortunately, in reality, the time signals are always electronically noisy, as shown in the lower time signal A s. Due to the electronic noise the time signal ÄS becomes an error of + - ΔΤ, which is passed to the engine controller 8 added. In order to keep this error ΔΤ as low as possible, the conversion of the integrated correcting, at least partially nonlinear signal characteristic 10 into a non-linear signal characteristic 9 with the element 4 for generating the nonlinear signal characteristic 9 took place. The problem of error propagation in the individual signals S and Time signal ÄS will be explained later. In the figure sequence 4 and 5, the problem will be explained in more detail, which arises when fast, in MEMS technology ge ¬ crafted, sensor elements 1 detect a pulse in the air intake 14 pulsie ¬ ing air mass flow Q metrologically. FIG. 4 a shows the air mass flow Q pulsating in the air intake pipe 14 as a function of the time t. At ¬ way of example here an ideal sinusoidal pulsation is shown. The real air mass flow Q thus moves here in the air intake pipe 14 between a maximum value Q ma x and a minimum value 0, which occurs when all the air inlet valves of Ver ¬ combustion engine 11 are closed, and the air mass flow Q in the air intake pipe 14 comes to a standstill. For the engine control
8 ist jedoch nur der gemittelte Luftmassenstrom Q von Interesse. Um den Mittelwert des Luftmassenstromes Q zu bilden, muss das Integral über die Funktion Q(t) verschwinden, also gleich Null werden. Dies ist in Figur 4a dargestellt, indem die schraffierten Flächen zwischen ti und t2 mit entgegengesetztem Vorzeichen gleich groß sind. Diese Integration kann aber nicht direkt am Luftmassenstrom Q(t) vorgenommen werden, sondern nur an dem vom Sensorelement 1 erzeugten Signal S(t) . Die typische Signalkenn¬ linie eines schnellen in MEMS-Technologie gefertigten Sensorelementes 1 ist in Figur 4b dargestellt. Im Luftmassenstrom- Q-Signal-S-Diagramm ist die nichtlineare Signalkennlinie 9 deutlich zu erkennen. Nach der Umsetzung des in Figur 4a dar- gestellten Luftmassenstromes Q(t) mit dem nichtlinearen Sensorelement 1 nach der in Figur 4b dargestellten Signalkennlinie8, however, only the average air mass flow Q is of interest. In order to form the mean value of the air mass flow Q, the integral must disappear via the function Q (t), ie equal to zero. This is illustrated in FIG. 4a in that the hatched areas between ti and t2 have the same sign with the opposite sign. However, this integration can not be made directly at the air mass flow Q (t), but only at the signal S (t) generated by the sensor element 1. The typical signal characteristic line ¬ a quick manufactured in MEMS technology, the sensor element 1 is illustrated in Figure 4b. The non-linear signal characteristic 9 can be clearly seen in the air mass flow Q signal S diagram. After the conversion of the air mass flow Q (t) shown in FIG. 4a with the non-linear sensor element 1 according to the signal characteristic shown in FIG. 4b
9 erhält man das in Figur 4c dargestellte zeitabhängige Signal S(t) . Durch die nichtlineare Signalkennlinie 9 weicht die Funktion S (t) nun deutlich von der idealen Sinusform ab. Dies wird in Figur 4c dargestellt. Auch hier ist dargestellt, dass die Flächen unter den zwei Halbwellen des periodischen Signals mit entgegengesetztem Vorzeichen gleich groß sein sollen, um den Mittelwert über das periodische Signal zu bilden. Die Integration von ti bis t2 über j" S(t)dt ist demnach Null. Dies ist in der durchgehenden horizontalen Linie in Figur 4c dargestellt. Weiterhin ist zu erkennen, dass diese Mittelwertlinie nun gegenüber dem realen Mittelwert durch die nichtlineare Sig¬ nalkennlinie 9 um den Wert 5s angehoben wurde. 5s stellt den Fehler dar, der sich aus der Nichtlinearität des schnellen, in MEMS-Technologie gefertigten, Sensorelementes 1 ergibt. Diesen Fehler gilt es zu vermeiden. Dazu ist in Figur 5a wiederum die ideale, sinusförmige Funktion Q(t) für den von der Zeit ab¬ hängigen Luftmassenstrom Q im Luftansaugrohr 14 dargestellt. Für die Mittelwertbildung im Luftmassenraum gilt wiederum, dass das Integral tl bis t2 j" Q(t)dt gleich Null werden muss. Zur Umsetzung des realen Luftmassenstromes Q mithilfe des Sensorelementes 1 in ein Signal S wird, wie schon aus Figur 4b bekannt, die in Figur 5b dargestellte nichtlineare Signalkennlinie 9 eingesetzt. Nach dem Stand der Technik wird diese nichtlineare Signalkennlinie 9 dann von einem Element 2 zur Umwandlung in eine lineare Signalkennlinie 10a umgesetzt. Den Übergang von der nichtlinearen Signalkennlinie 9 zur linearen Signalkennlinie 10a kann für jeden im Messbereich des Sensorelementes 1 liegenden Luftmassenstrom Q und jeden im Messbereich liegenden Rohrquerschnitt, entsprechend der Anforderungen der Nutzer des Luftmassenmessers mithilfe eines Kennfeldes angepasst werden. Dieses Kennfeld kann zum Beispiel in einem elektronischen Speicher im Element 2 zur Umwandlung abgelegt sein. Wenn man nun nach der Linearisierung des nichtlinearen Signals S mithilfe des Filterelementes 3 eine elektronische Integration j" S(t)dt über die Signalfunktion S(t) vornimmt erhält man keinerlei Abweichung des Mittelwertes von dem im realen Luftmassenraum vorliegenden Mittelwert für den Luftmassenstrom Q. Der durch die nichtlineare Sensorkennlinie 9 des Sensorelementes 1 entstehende Integrationsfehler wurde durch die Linearisierung des Signals mit dem Element 2 zur Umwandlung ausgemerzt. Der so ermittelte Messwert für den mittleren Luftmassenstrom Q muss jedoch in Form eines Zeitsignals an die Motorsteuerung 8 weitergegeben werden. Da sich das elektronische Rauschen im Zeitsignal besonders bei kleinen Signalwerten für den Luftmassenstrom Q deutlich bemerkbar macht, ist die Umwandlung der linearen Signalkennlinie nach Figur 5c nach der Ausführung der Integration durch das Filterelement 3 durch das Element 4 zur Erzeugung einer nichtlinearen Signalkennlinie 10 notwendig. Diese nun wieder nichtlineare Signalkennlinie eignen sich besonders gut, um ein zeitabhängiges Signal, das proportional zum Luftmassenstrom Q in dem Luftansaugrohr 14 ist, an die Motorsteuerung 8 weiterzugeben, ohne einen großen Fehler ΔΤ im Zeitsignal AS zu erzeugen. 9, the time-dependent signal shown in FIG. 4c is obtained S (t). Due to the nonlinear signal characteristic 9, the function S (t) now deviates significantly from the ideal sinusoidal shape. This is illustrated in FIG. 4c. Again, it is shown that the areas under the two half-waves of the periodic signal of opposite sign should be equal in size to form the average over the periodic signal. The integration of ti to t2 over j "S (t) dt is therefore zero. This is shown in the continuous horizontal line in Figure 4c. Furthermore, it can be seen that these mean line now compared to the real average value by the nonlinear Sig ¬ nalkennlinie 9 5s represents the error resulting from the nonlinearity of the fast sensor element 1 fabricated in MEMS technology 1. This error should be avoided, and again the ideal sinusoidal function Q is shown in FIG (t) for the air mass flow Q dependent on time in the air intake pipe 14. For averaging in the air mass space, it holds again that the integral t1 to t2 j " Q (t) dt must become equal to zero. For the conversion of the real air mass flow Q by means of the sensor element 1 into a signal S, as already known from FIG. 4b, the non-linear signal characteristic 9 shown in FIG. 5b is used. According to the prior art, this non-linear signal characteristic 9 is then converted by an element 2 for conversion into a linear signal characteristic 10a. The transition from the nonlinear signal characteristic 9 to the linear signal characteristic 10a can be adapted for each air mass flow Q lying in the measuring range of the sensor element 1 and any pipe cross section lying in the measuring range, according to the requirements of the users of the air mass meter using a characteristic diagram. This map can be stored, for example, in an electronic memory in the element 2 for conversion. If, after the linearization of the nonlinear signal S by means of the filter element 3, an electronic integration j " S (t) dt is carried out via the signal function S (t), no deviation of the mean value from the average air mass flow Q present in the real air mass space is obtained. Der by the nonlinear sensor characteristic 9 of the Sensor element 1 resulting integration error was eliminated by the linearization of the signal with the element 2 for conversion. However, the measured value for the mean air mass flow Q thus determined must be forwarded to the engine control unit 8 in the form of a time signal. Since the electronic noise in the time signal is clearly noticeable in the case of small signal values for the air mass flow Q, the conversion of the linear signal characteristic according to FIG. 5c after the implementation of the integration by the filter element 3 by the element 4 for generating a nonlinear signal characteristic 10 is necessary. These again non-linear signal characteristic are particularly well suited to pass a time-dependent signal, which is proportional to the air mass flow Q in the air intake pipe 14, to the motor controller 8, without generating a large error ΔΤ in the time signal AS.
Die Signalverarbeitungsverfahren nach dem Stand der Technik berücksichtigen jedoch nicht das unterschiedliche Ansprechverhalten der Bauelemente des Sensorelementes 1. Bei einem Sensorelement 1, das beispielsweise einen ersten und einen zweiten Temperatursensor aufweist, zwischen denen ein Heizelement angeordnet ist, weisen das erste Temperatursensor- element, das zweite Temperatursensorelement und das Heizelement ein in der Regel unterschiedliches Ansprechverhalten auf. Das erste Temperatursensorelement wird zum Beispiel nur vom Luft¬ massenstrom gekühlt und nicht vom Heizelement erwärmt . Das zweite Temperatursensorelement hingegen wird zunächst vom Heizelement erwärmt und dann mit zunehmendem Luftmassenstrom immer weiter abgekühlt. Das Heizelement wird vom Luftmassenstrom aus- schließlich gekühlt. Alle diese Bauteile weisen zudem Ferti¬ gungstoleranzen auf. Diese Fehlerquellen verschlechtern wiederum die Auflösung bei der Zeitdifferenzmessung während der Übertragung des Zeitsignals ÄS an die Motorsteuerung 8. Daher ist es ein erfindungswesentlicher Gedanke, die nichtlineare Sensorkennlinie 9 nicht einfach nur zu linearisieren, sondern sie mit Informationen über die speziellen Eigenschaften des Sensorelementes 1 zu versehen und damit eine korrigierende, zumindest abschnittsweise nichtlineare Signalkennlinie 10 zu schaffen, die Bauteiltoleranzen und unterschiedliche Ansprechzeiten der Temperatursensorelemente und des Heizelementes berücksichtigt. However, the signal processing methods according to the prior art do not take into account the different response behavior of the components of the sensor element 1. In a sensor element 1 having, for example, a first and a second temperature sensor, between which a heating element is arranged, have the first temperature sensor element, the second Temperature sensor element and the heating element on a generally different response. The first temperature sensor element is for example only cooled by the air mass flow ¬ and not heated by the heating element. The second temperature sensor element, however, is first heated by the heating element and then cooled further with increasing air mass flow. The heating element is exclusively cooled by the air mass flow. All these components also have Ferti ¬ tolerances. These sources of error in turn degrade the resolution in the time difference measurement during the transmission of the time signal ÄS to the motor controller 8. Therefore, it is an essential idea of the invention, not just linearize the non-linear sensor characteristic 9, but with information about the special properties to provide the sensor element 1 and thus to provide a correcting, at least partially non-linear signal characteristic 10, the component tolerances and different response times of the temperature sensor elements and the heating element taken into account.
Figur 6a zeigt ein Beispiel für ein fehlerhaftes Signal, das durch die Bauteiltoleranzen und die unterschiedlichen Ansprechzeiten der Temperatursensorelemente 18, 19 und des Heizelementes 20 entstehen kann. Q steht im hier gezeigten Diagramm für denFIG. 6 a shows an example of a faulty signal, which can arise due to the component tolerances and the different response times of the temperature sensor elements 18, 19 and of the heating element 20. Q stands in the diagram shown here for the
Luftmassenstrom. Der Fehler, der entsprechend der Bauteiltoleranzen und unterschiedlichen Ansprechzeiten entsteht, wird in Prozent ausgegeben. Zunächst entstehen bei geringen Luftmassenströmen Q positive Fehler, da das erste Temperatursensor- element 18 ausschließlich gekühlt wird, das zweite Tempera¬ tursensorelement 19 durch den geringen Luftmassenstrom Q nur wenig gekühlt wird und dadurch überproportional stark von dem Heizelement 20 aufgeheizt wird. Bei zunehmendem Luftmassenstrom Q korrigiert sich der Fehler immer weiter, wobei zum Beispiel bei einem Luftmassenstrom Q von hundert relativen Einheiten der soeben beschriebene Fehler vollständig kompensiert ist. Nun jedoch beginnt der höhere Luftmassenstrom Q am zweiten Temperatursensorelement 19 zu dominieren und dieses überpropor¬ tional stark abzukühlen, woraufhin sich ein negativer Fehler einstellt, der sich bis etwa vierhundert relative Einheiten des Luftmassenstromes Q aufbaut. Danach überlagern sich die im Luftmassenmesser durch die Bauteiltoleranzen und unterschiedlichen Ansprechzeiten hervorgerufenen Fehler, wodurch es zu einer Annäherung an den optimalen fehlerfreien Bereich für den Luftmassenstrom kommt. Air mass flow. The error, which arises according to the component tolerances and different response times, is output in percent. First, at low air mass flows Q positive errors, since the first Temperatursensor- element 18 is exclusively cooled, the second tempera ¬ tursensorelement 19 is cooled only slightly by the low air mass flow Q and is thus disproportionately heated by the heating element 20. As the air mass flow Q increases, the error continues to be corrected, wherein, for example, with an air mass flow Q of one hundred relative units, the error just described is completely compensated. Now, however, the higher air mass flow Q starts to dominate at the second temperature sensor element 19 and this cool überpropor ¬ tion strong, whereupon a negative error occurs, which builds up to about four hundred relative units of the air mass flow Q. After that, the errors caused in the air mass meter by the component tolerances and different response times overlap, which leads to an approximation to the optimum, error-free range for the air mass flow.
In Figur 6b ist das umgewandelte Signal des Sensorelementes 1 in Abhängigkeit vom realen Luftmassenstrom Q dargestellt. Die gestrichelte Linie 10a zeigt die nichtlineare Sensorkennlinie 9 nach ihrer einfache Linearisierung. Dahingegen zeigt die Kurve mit dem Bezugszeichen 10 die korrigierende, zumindest ab¬ schnittsweise nichtlineare Signalkennlinie 10, die aus der nichtlinearen Sensorkennlinie 9 unter Berücksichtigung der Bauteiltoleranzen und der unterschiedlichen Ansprechzeiten erzeugt wurde. Im ersten Bereich wurde der positive Fehler aus Figur 6a entsprechend in die korrigierende, zumindest ab- schnittsweise nichtlineare Signalkennlinie 10 aufgenommen, wobei im Bereich um etwa hundert relative Einheiten des Mas¬ senstromes ein fehlerfreier Bereich des Sensorelementes 1 erreicht ist, in dem die korrigierende, zumindest abschnitts¬ weise nichtlineare Signalkennlinie 10 weitgehend einer linearen Signalkennlinie entspricht, woraufhin sich dann ein Abschnitt eines negativen Fehlers anschließt, der wiederum zu starken Abweichungen der korrigierende, zumindest abschnittsweise nichtlineare Signalkennlinie 10 von der linearen Signalkennlinie 10a führt. FIG. 6b shows the converted signal of the sensor element 1 as a function of the actual air mass flow Q. The dashed line 10a shows the nonlinear sensor characteristic curve 9 after its simple linearization. In contrast, the curve shows the reference numeral 10, the correcting, at least from ¬ section-wise non-linear signal response 10 resulting from the nonlinear sensor characteristic 9 was generated taking into account the component tolerances and the different response times. In the first region of the positive error of Figure 6a was prepared according to the at least taken up in sections non-linear signal characteristic curve 10 corrected, whereby in the area by about hundred relative units of Mas ¬ senstromes a fault-free region of the sensor element 1 is reached, in which the corrective, at least portion ¬ as non-linear signal characteristic 10 largely corresponds to a linear signal characteristic curve, after which is then followed by a section of a negative error, which in turn leads to strong variations in the correcting, at least partially non-linear signal characteristic curve 10 of the linear signal characteristic 10a.
Figur 7 zeigt ein Sensorelement 1 eines Luftmassenmessers 6. Das Sensorelement 1 weist ein Substrat 17 auf, auf den ein erstes Temperatursensorelement 18 und ein zweites Temperatursensor¬ element 19 angeordnet sind. Zwischen dem ersten Temperatur- sensorelement 18 und dem zweiten Temperatursensorelement 19 ist auf dem Substrat 17 ein Heizer 20 angeordnet. Die Richtung des Luftmassenstromes Q ist mit dem Pfeil bezeichnet. Figure 7 shows a sensor element 1 of an air flow sensor 6. The sensor element 1 includes a substrate 17, on which a first temperature-sensor element 18 and a second temperature sensor element are arranged ¬ 19th Between the first temperature sensor element 18 and the second temperature sensor element 19, a heater 20 is arranged on the substrate 17. The direction of the air mass flow Q is indicated by the arrow.

Claims

Luftmassenmesser (6) mit einem Sensorelement (1) zur Erfassung eines Luftmassenstroms (Q) und zur Erzeugung eins Signals (S) und mit einer elektronischen Schaltung (7) zur Verarbeitung des Signals (S) vom Sensorelement (1), wobei das Sensorelement (1) eine nichtlineare Signalkennlinie (9) erzeugt, d a d u r c h g e k e n n z e i c h n e t , dass die elektronische Schaltung (7) Air mass meter (6) with a sensor element (1) for detecting an air mass flow (Q) and for generating a signal (S) and with an electronic circuit (7) for processing the signal (S) from the sensor element (1), wherein the sensor element ( 1) generates a non-linear signal characteristic (9), characterized in that the electronic circuit (7)
zunächst ein Element (2) zur Umwandlung der nichtlinearen Signalkennlinie (9) von dem Sensorelement (1) in eine korrigierende, zumindest abschnittsweise nichtlineare Signalkennlinie (10) aufweist, first an element (2) for converting the non-linear signal characteristic (9) of the sensor element (1) in a correcting, at least partially non-linear signal characteristic (10),
dann ein Filterelement (3) aufweist, then a filter element (3),
dann ein Umwandlungselement (4) zur Umwandlung der korrigierende, zumindest abschnittsweise nichtlineare Sig¬ nalkennlinie (10) in eine nichtlineare Signalkennlinie (9) aufweist und having then a conversion element (4) for converting the corrected, at least partially non-linear Sig ¬ nalkennlinie (10) in a non-linear signal characteristic (9) and
dann ein Weitergabeelement (5) zur Weitergabe der vom Sensorelement (1) erfassten und durch das Linearisie¬ rungselement (2), das Filterelement (3) und das Umwand¬ lungselement (4) verarbeiteten Signale (S) aufweist. then a relay element (5) for relaying the sensor element (1) detected and by the Linearisie ¬ tion element (2), the filter element (3) and the conversion element ¬ (4) processed signals (S).
Luftmassenmesser (6) nach Anspruch 1, d a d u r c h g e k e n n z e i c h n e t , dass das Sensorelement (1) und die elektronische Schaltung (7) auf einem einzigen Halbleiterelement ausgebildet sind. Air mass meter (6) according to claim 1, characterized in that the sensor element (1) and the electronic circuit (7) are formed on a single semiconductor element.
Luftmassenmesser (6) nach Anspruch 1 oder 2, d a d u r c h g e k e n n z e i c h n e t , dass das Sensorelement (1) und die elektronische Schaltung (7) in Mikrosystem-Technologie hergestellt sind. Air mass meter (6) according to claim 1 or 2, characterized in that the sensor element (1) and the electronic circuit (7) are manufactured in microsystem technology.
Luftmassenmesser (6) nach Anspruch 1, 2 oder 3, d a d u r c h g e k e n n z e i c h n e t , dass Sensorelement (1) ein erstes Temperatursensorelement und ein zweites Temperatursensorelement aufweist . Luftmassenmesser (6) nach Anspruch 4, d a d u r c h g e k e n n z e i c h n e t , dass Sensorelement (1) ein Heizelement (20) aufweist, das zwischen dem ersten und dem zweiten Temperatursensorelement (18, 19) angeordnet ist. Air mass meter (6) according to claim 1, 2 or 3, characterized in that the sensor element (1) comprises a first temperature sensor element and a second temperature sensor element. Air mass meter (6) according to claim 4, characterized in that sensor element (1) has a heating element (20) which is arranged between the first and the second temperature sensor element (18, 19).
Verfahren zur Verarbeitung von Signalen (S) eines Luftmassenmessers (6), wobei der Luftmassenmesser (6) ein Sensorelement (1) zur Erfassung eines Luftmassenstroms (Q) und zur Erzeugung eines Signals (S) aufweist und eine elektronische Schaltung (7) zur Verarbeitung des Signals (S) vom Sensorelement (1) aufweist, wobei das Sensorelement (1) eine nichtlineare Signalkennlinie (9) erzeugt, d a d u r c h g e k e n n z e i c h n e t , dass Method for processing signals (S) of an air mass meter (6), wherein the air mass meter (6) has a sensor element (1) for detecting an air mass flow (Q) and for generating a signal (S) and an electronic circuit (7) for processing the signal (S) from the sensor element (1), wherein the sensor element (1) generates a non-linear signal characteristic (9), characterized in that
zunächst die Umwandlung der nichtlinearen Signalkennlinie (9) vom Sensorelement (1) in eine korrigierende nicht¬ lineare Signalkennlinie (10) erfolgt, first takes place the conversion of the non-linear signal characteristic (9) from the sensor element (1) in a corrective not ¬ linear signal characteristic (10),
dann eine Filterung der korrigierenden nichtlinearen Signalkennlinie (lO)erfolgt, then a filtering of the corrective non-linear signal characteristic (10) takes place,
dann eine Umwandlung der gefilterten korrigierende nichtlineare Signalkennlinie (10) in eine nichtlineare Signalkennlinie (9) erfolgt und then a conversion of the filtered corrective non-linear signal characteristic (10) into a non-linear signal characteristic (9) takes place, and
dann eine Weitergabe der von dem Sensorelement (1) erfassten und durch das Linearisierungselement (2), das Filterelement (3) und das Umwandlungselement (4) verarbeiteten Signale (S) erfolgt. then a passing of the sensor element (1) detected and by the linearization element (2), the filter element (3) and the conversion element (4) processed signals (S) takes place.
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KR20160043058A (en) 2016-04-20
US9885594B2 (en) 2018-02-06
CN105431716A (en) 2016-03-23
JP6362696B2 (en) 2018-07-25
WO2015022156A1 (en) 2015-02-19
DE102013215921A1 (en) 2015-03-05
KR101778904B1 (en) 2017-09-15
CN105431716B (en) 2019-03-08
US20160202099A1 (en) 2016-07-14

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