EP1255926B1 - Method and device for calibrating a pressure sensor - Google Patents

Method and device for calibrating a pressure sensor Download PDF

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Publication number
EP1255926B1
EP1255926B1 EP20010911382 EP01911382A EP1255926B1 EP 1255926 B1 EP1255926 B1 EP 1255926B1 EP 20010911382 EP20010911382 EP 20010911382 EP 01911382 A EP01911382 A EP 01911382A EP 1255926 B1 EP1255926 B1 EP 1255926B1
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EP
European Patent Office
Prior art keywords
pressure
sensor
region
low
internal combustion
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.)
Expired - Fee Related
Application number
EP20010911382
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German (de)
French (fr)
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EP1255926A2 (en
Inventor
Klaus Joos
Jens Wolber
Thomas Frenz
Hansjoerg Bochum
Matthias Kuesell
Markus Amler
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Robert Bosch GmbH
Original Assignee
Robert Bosch GmbH
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Filing date
Publication date
Priority to DE10003906 priority Critical
Priority to DE2000103906 priority patent/DE10003906A1/en
Application filed by Robert Bosch GmbH filed Critical Robert Bosch GmbH
Priority to PCT/DE2001/000271 priority patent/WO2001055573A2/en
Publication of EP1255926A2 publication Critical patent/EP1255926A2/en
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Publication of EP1255926B1 publication Critical patent/EP1255926B1/en
Expired - Fee Related legal-status Critical Current
Anticipated expiration legal-status Critical

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Classifications

    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02MSUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
    • F02M65/00Testing fuel-injection apparatus, e.g. testing injection timing ; Cleaning of fuel-injection apparatus
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02DCONTROLLING COMBUSTION ENGINES
    • F02D41/00Electrical control of supply of combustible mixture or its constituents
    • F02D41/24Electrical control of supply of combustible mixture or its constituents characterised by the use of digital means
    • F02D41/2406Electrical control of supply of combustible mixture or its constituents characterised by the use of digital means using essentially read only memories
    • F02D41/2425Particular ways of programming the data
    • F02D41/2429Methods of calibrating or learning
    • F02D41/2441Methods of calibrating or learning characterised by the learning conditions
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02DCONTROLLING COMBUSTION ENGINES
    • F02D41/00Electrical control of supply of combustible mixture or its constituents
    • F02D41/24Electrical control of supply of combustible mixture or its constituents characterised by the use of digital means
    • F02D41/2406Electrical control of supply of combustible mixture or its constituents characterised by the use of digital means using essentially read only memories
    • F02D41/2425Particular ways of programming the data
    • F02D41/2429Methods of calibrating or learning
    • F02D41/2451Methods of calibrating or learning characterised by what is learned or calibrated
    • F02D41/2474Characteristics of sensors
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02DCONTROLLING COMBUSTION ENGINES
    • F02D41/00Electrical control of supply of combustible mixture or its constituents
    • F02D41/30Controlling fuel injection
    • F02D41/38Controlling fuel injection of the high pressure type
    • F02D41/3809Common rail control systems
    • F02D41/3836Controlling the fuel pressure
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02DCONTROLLING COMBUSTION ENGINES
    • F02D41/00Electrical control of supply of combustible mixture or its constituents
    • F02D41/22Safety or indicating devices for abnormal conditions
    • F02D41/222Safety or indicating devices for abnormal conditions relating to the failure of sensors or parameter detection devices
    • F02D2041/223Diagnosis of fuel pressure sensors
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02DCONTROLLING COMBUSTION ENGINES
    • F02D2250/00Engine control related to specific problems or objectives
    • F02D2250/31Control of the fuel pressure
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02DCONTROLLING COMBUSTION ENGINES
    • F02D41/00Electrical control of supply of combustible mixture or its constituents
    • F02D41/24Electrical control of supply of combustible mixture or its constituents characterised by the use of digital means
    • F02D41/2406Electrical control of supply of combustible mixture or its constituents characterised by the use of digital means using essentially read only memories
    • F02D41/2425Particular ways of programming the data
    • F02D41/2429Methods of calibrating or learning
    • F02D41/2432Methods of calibration
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02DCONTROLLING COMBUSTION ENGINES
    • F02D41/00Electrical control of supply of combustible mixture or its constituents
    • F02D41/30Controlling fuel injection
    • F02D41/38Controlling fuel injection of the high pressure type
    • F02D41/3809Common rail control systems
    • F02D41/3836Controlling the fuel pressure
    • F02D41/3845Controlling the fuel pressure by controlling the flow into the common rail, e.g. the amount of fuel pumped
    • F02D41/3854Controlling the fuel pressure by controlling the flow into the common rail, e.g. the amount of fuel pumped with elements in the low pressure part, e.g. low pressure pump

Abstract

The invention relates to a method and a device for calibrating a pressure sensor (7) of a fuel dosing system of an internal combustion engine. Said fuel dosing system comprises a high-pressure pump (2) that delivers fuel from a low-pressure zone (ND) to a high-pressure zone (HD). The injectors (5) that dose the fuel from the high-pressure zone (HD) into the combustion chambers (6) of the internal combustion engine are controlled according to working characteristics. The dosing system further comprises the pressure sensor (7) that measures the pressure in the high-pressure zone (HD). The aim of the invention is to calibrate the pressure sensor (7) in such a manner that the offset-error can be reduced to a minimum. To this end, the pressure in the high-pressure zone (HD) is used as a reference pressure, the pressure in the high-pressure zone (HD) is measured by the pressure sensor (7) as the sensor pressure and the characteristic line of the pressure sensor (7) is corrected in such a manner that the difference from reference pressure and sensor pressure is reduced to a minimum.

Description

    State of the art
  • The present invention relates to a method and apparatus for calibrating a pressure sensor of a fuel metering system of an internal combustion engine, such as an engine. From DE 195 47 647 known. The fuel metering system includes a high pressure pump for delivering fuel from a low pressure region to a high pressure region, injectors controllable in dependence on operating characteristic for metering the fuel from the high pressure region into combustion chambers of the internal combustion engine and the pressure sensor for measuring the pressure in the high pressure region.
  • The fuel metering system is designed, for example, as a Canton-Rail direct fuel injection system with a prefeed pump and an on-demand or demand-controlled high-pressure pump. The prefeed pump is, for example, designed as an electric fuel pump and delivers fuel from a fuel reservoir into the low-pressure region of the fuel metering system. In the low pressure range prevails an admission pressure of for example 4 bar. The high-pressure pump delivers the fuel from the low-pressure region into a high-pressure accumulator in the high-pressure region of the fuel metering system. In the high pressure accumulator prevails at gasoline fuel For example, a pressure of 150 to 200 bar and diesel fuel at a pressure of, for example, 1500 to 2000 bar. From the high-pressure accumulator branch off from several injectors, which inject the fuel from the high-pressure accumulator with the applied there injection pressure in the combustion chambers of the internal combustion engine with appropriate control. The injectors can be controlled depending on specific operating parameters. Furthermore, a pressure sensor is arranged in the high-pressure accumulator, by means of which the injection pressure prevailing in the high-pressure accumulator is determined and a corresponding electrical signal is passed to a control unit of the internal combustion engine. Finally, from the high-pressure region of the fuel metering system, a pressure control line branches off, which opens into the low-pressure region via a pressure control valve. From the low-pressure area of the fuel supply system branches off a low-pressure line, which leads via a low-pressure regulator back into the fuel tank.
  • Pressure sensors, such as those used in fuel metering systems, typically have a static offset error, i. the zero point is not displayed reliably. An offset error causes the measured value of pressure sensors, especially in the low pressure range, to have large relative deviations from the actual pressure value.
  • In the starter phase of direct-injection rail internal combustion engines is usually a low pressure. The internal combustion engine is usually started with a low pre-pressure generated by the prefeed pump, and only later is switched to the high pressure. Since the injected via the injectors into the combustion chambers fuel mass is heavily dependent on the pressure prevailing in the high-pressure accumulator injection pressure, this would have in the starting phase of the internal combustion engine to be included in the calculation of the injection time. Due to the above-described inaccuracies of the pressure sensor, especially at low pressures, but this is usually not possible. Therefore, according to the prior art, the start of a direct-injection internal combustion engine generally proceeds without the inclusion of the current pressure prevailing in the high-pressure region.
  • From the aforementioned disadvantages of the prior art, the object of the present invention is to calibrate a pressure sensor of a fuel metering system of an internal combustion engine such that the offset error is minimized.
  • To achieve this object, the invention proposes, starting from the method of the type mentioned above, that a pressure prevailing in the high-pressure region is used as the reference pressure, that the pressure prevailing in the high-pressure region is measured as the sensor pressure by the pressure sensor, and the characteristic of the pressure sensor is such is corrected so that the difference between reference pressure and sensor pressure is minimized.
  • Advantages of the invention
  • Since the offset error from pressure sensor to pressure sensor has a high degree of dispersion, no generally valid application for minimizing an offset error in pressure sensors is possible, but each pressure sensor must be individually adjusted.
  • According to the invention, an adaptation of the sensor characteristic curve is thus carried out individually for each pressure sensor. The inventive method is based on the consideration that in a measuring range. in which the pressure sensor the largest offset error, the reference pressure is determined with a higher accuracy than the sensor pressure can be measured by the pressure sensor. If the sensor characteristic curve is then corrected in such a way that the difference between the differential pressure and the sensor pressure is minimized, preferably set to zero, it can be assumed that the pressure sensor calibrated according to the method of the invention has a higher measuring accuracy than a pressure sensor with an unadapted sensor characteristic.
  • According to an advantageous development of the present invention, it is proposed that, after measuring the sensor pressure by the pressure sensor and before correcting the characteristic curve of the pressure sensor, it be checked whether the measured sensor pressure is within predefined plausibility limits. If the sensor pressure is outside a plausibility check, it is assumed that the pressure sensor is defective. In this case, an adaptation of the sensor characteristic makes no sense, the calibration of the pressure sensor is aborted and a corresponding error message is output.
  • The prerequisite for selecting the reference pressure is that the reference pressure can be determined with a higher accuracy than the sensor pressure can be measured by the pressure sensor.
  • According to the present invention, it is proposed that the pressure in the high-pressure region is produced by activating a prefeed pump of the fuel metering system for generating the low-pressure in the low-pressure region and guiding the low-pressure into the high-pressure region. Thus, the pre-pressure generated by the feed pump is also in the High pressure range of the fuel metering system.
  • The low-pressure regulator of the fuel metering system has, for example, an accuracy of about ± 6%, which corresponds to a pre-pressure of about 4 bar ± 240 mbar. A pressure set at the low pressure regulator can thus be determined with a higher accuracy than the sensor pressure can be measured by the pressure sensor in the high pressure region. The pressure prevailing in the low-pressure region can, for example, be conducted into the high-pressure region via additional pressure-equalizing lines or by opening already existing connecting lines between the low-pressure region and the high-pressure region. As reference pressure, the pressure set at a low pressure regulator of the fuel metering system in the low pressure range is then advantageously used.
  • According to another preferred embodiment of the present invention, it is proposed that the pressure from the low-pressure region through open inlet valves and exhaust valves of the high-pressure pump is passed into the high-pressure region, wherein the pressure set as the reference pressure of the low-pressure regulator of the fuel metering system in the low-pressure region taking into account the opening pressure of the intake valves and exhaust valves of the high pressure pump is used. This embodiment has the advantage that no additional pressure compensation lines have to be provided between the low-pressure region and the high-pressure region; rather, an already existing connection between the low pressure area and the high pressure area via the inlet valves, the high pressure pump and the outlet valves is used to direct the pressure from the low pressure area to the high pressure area. The opening pressures of the inlet and outlet valves of the high-pressure pump also have an accuracy of about ± 6%, so that the reference pressure can be determined with an accuracy of at least ± 500 mbar. In a high pressure sensor used in a fuel metering system of a direct injection gasoline engine with a measuring range of about 150 bar, this corresponds to an accuracy of about ± 0.3%. With such high accuracy, the sensor pressure can not be determined by the pressure sensor.
  • Alternatively, it is proposed according to a further preferred embodiment of the present invention that the reference pressure is measured by a high-precision low-pressure sensor arranged at least at times in the high-pressure region. The low-pressure sensor can be introduced, for example, for the purpose of measuring the reference pressure in the high-pressure region of the fuel metering system and removed therefrom after the measurement. Another possibility is that the low-pressure sensor is permanently installed in the low-pressure region and that the reference pressure used is the measured value of the low-pressure sensor minus the opening pressures of the inlet and outlet valves of the high-pressure pump. The low pressure sensor has a measuring range of about 5 bar. Because of this limited measurement range compared to the sensor of the fuel metering system, relative inaccuracies (in percent) have less of an effect on the absolute value (in bar) of the measured pressure. With the help of the low pressure sensor, the reference pressure can thus be measured much more accurately than the sensor pressure can be measured by the pressure sensor.
  • According to another advantageous development of the present invention, it is proposed that the reference pressure is the ambient pressure. The ambient pressure is usually present with a much higher accuracy than the sensor pressure through the Pressure sensor can be measured. The ambient pressure can be measured via a special ambient pressure sensor. After a predetermined service life of the internal combustion engine, the ambient pressure can also be measured by a Saugrohrdrucksensor. The ambient pressure can also be entered manually. For example, the value entered may be a value measured at the location or a value typical of the location.
  • Another advantage of this development according to the invention results in an additional possibility of diagnosis of the fuel metering system. After adaptation of the sensor characteristic curve, the prefeed pump can be activated, so that a pre-pressure builds up. The pre-pressure is directed to the high pressure area. The in the high pressure area, in particular in the high-pressure accumulator, adjusting pressure is measured and stored as normal value in a memory of the control unit of the internal combustion engine. During operation of the internal combustion engine, the pressure setting in the high-pressure region during a longer flow of the prefeed pump is then compared with the stored normal value. If the pressure and the normal value deviate from each other beyond a predetermined limit value, an error is concluded in the low-pressure region of the fuel metering system.
  • According to yet another advantageous development of the present invention, it is proposed that the reference pressure of the opening pressure of a pressure control valve or a pressure limiting valve of the fuel metering system is used in a specific operating state of the internal combustion engine. A pressure control valve of the fuel metering system is usually normally closed with spring load. The pressure control valve is thus closed without electrical control and opens at a predetermined pressure. This Opening pressure may depend on environmental parameters, such as engine speed, mass flow through the pressure control valve, ambient temperature, etc., but is generally known in certain operating conditions with relatively high accuracy. For example, in direct-injection gasoline internal combustion engines at idle speed, the opening pressure of the pressure control valve with an accuracy of about ± 2.5 bar known. The inaccuracies of the pressure sensor of the fuel metering system are usually much higher. If, during operation of the internal combustion engine at idle speed, the pressure control valve opens, it can be assumed that prevails in the high pressure region, a pressure which corresponds approximately to the opening pressure of the pressure control valve. This pressure is then used as the reference pressure for the adaptation of the sensor characteristic.
  • A fuel metering system with an on-demand high pressure pump does not have a pressure control valve but only a passive, spring loaded closed relief valve - (pressure relief valve) with the same pressure values as a pressure control valve. The process of the invention can be carried out here in an analogous manner.
  • This development according to the invention has the additional advantage that errors of the fuel metering system can be detected during operation of the internal combustion engine. During operation of the motor vehicle, the pressure control valve is switched off during certain operating states, ie closed. The pressure which is established in the high-pressure region is measured and compared with a desired value which, depending on various operating parameters, in particular the mass flow through the pressure control valve and the temperature of the pressure control valve, in the control device Internal combustion engine is stored. If the measured pressure deviates from the desired value beyond a predetermined limit value, it is assumed that there is a fault in the fuel metering system. Conceivable operating states for this function test are, for example, during a fuel cut or in an idling phase of the internal combustion engine. In order to limit the influence of temperature on the functional test, it is additionally conceivable to carry out the functional test only within a predetermined temperature range. This is easily possible since the function test reacts to slow changes in the fuel metering system and it is usually sufficient to carry out the functional test once per trip.
  • According to a preferred embodiment of the present invention, it is proposed that the method be carried out automatically during the starting process of the internal combustion engine after switching on the ignition and before the activation of the starter. During this period, a pre-pressure in the low-pressure region of the fuel metering system is established by the prefeed pump; in the high pressure area is still no injection pressure.
  • Furthermore, it is proposed that the method be carried out automatically during the overrun of the internal combustion engine after switching off the internal combustion engine and before switching off the ignition. During the wake, injection pressure is no longer present in the high pressure area of the fuel metering system; The prefeed pump continues to build up a form.
  • Finally, it is proposed that the method after assembly or after a repair of the fuel metering system of the internal combustion engine, in particular after replacement of the pressure sensor, is carried out. With the help of a suitable tester, the pre-feed pump can be controlled in such a way that it builds up a pre-pressure. The remaining elements of the fuel metering system are controlled in such a way that no injection pressure is applied in the high-pressure region and that the admission pressure is conducted from the low-pressure region into the high-pressure region.
  • As a solution to the object of the present invention, starting from the device for calibrating a pressure sensor of the aforementioned type, further proposed that the device comprises means for performing the method according to one of claims 1 to 11.
  • drawings
  • A preferred embodiment of the present invention will be explained in more detail below with reference to the drawings. Show it:
  • Fig. 1
    a flow diagram of a method according to the invention according to a preferred embodiment; and
    Fig. 2
    a fuel metering system of an internal combustion engine, in which a pressure sensor by means of the inventive method Fig. 1 is calibrated.
    Description of the embodiments
  • In FIG. 1 FIG. 3 is a flow chart of a preferred embodiment of a method for calibrating a pressure sensor of a fuel metering system of an internal combustion engine. In FIG. 2 is a common rail fuel direct injection system trained fuel metering system shown. It has a prefeed pump 1 and an on-demand or demand-controlled high-pressure pump 2. The prefeed pump 1 is designed as an electric fuel pump and delivers fuel from a fuel reservoir 3 into a low-pressure region ND of the fuel metering system. In the low pressure range ND there is a pre-pressure of about 4 bar.
  • The high-pressure pump 2 conveys the fuel from the low-pressure region ND into a high-pressure reservoir 4, the so-called rail, in a high-pressure region HD of the fuel metering system. In the high-pressure accumulator 4 prevails at gasoline fuel pressure of about 150 to 200 bar and diesel fuel at a pressure of about 1500 to 2000 bar. From the high-pressure accumulator 4 four injectors branch off 5, which are controlled depending on the operating parameters and inject the fuel from the high-pressure accumulator 4 with the applied there injection pressure in combustion chambers 6 of the internal combustion engine with appropriate control.
  • In addition, a pressure sensor 7 is arranged in the high-pressure accumulator 4, by which the injection pressure prevailing in the high-pressure accumulator 4 is determined and a corresponding electrical signal is passed to a control unit 8 of the internal combustion engine. The signal lines 9 are in FIG. 2 shown in dashed lines. Finally, a pressure control line 10 branches off from the high-pressure accumulator 4 of the fuel metering system, which opens into the low-pressure region ND via a pressure control valve 11.
  • From the low-pressure region ND of the fuel supply system branches off a low-pressure line 12, which leads via a low-pressure regulator 13 back into the fuel reservoir 3. Between the prefeed pump 1 and the high-pressure pump 2 is a Filter element 14 is arranged. From the high-pressure pump 2, a leak line 15 branches off, via which leak oil or gasoline of the high-pressure pump 2 can flow back into the fuel tank 3.
  • The pressure sensor 7 as used in the fuel metering system has a static offset error, i. the zero point is not displayed reliably. An offset error causes the reading of the pressure sensor. 7, in particular in the low-pressure region, has large relative deviations from the actual prevailing pressure value.
  • In the starter phase of direct-injection common-rail internal combustion engines there is usually a low pressure in the high-pressure accumulator 4. The internal combustion engine is usually started with a low pre-pressure generated by the feed pump 1, and only later is switched to the high pressure. Since the fuel mass injected into the combustion chambers 6 via the injectors 5 is heavily dependent on the injection pressure prevailing in the high-pressure accumulator 4, it would have to be included in the calculation of the injection time in the starting phase of the internal combustion engine. Due to the above-described inaccuracies of the pressure sensor 7, in particular at low pressures, but this is usually not possible. Therefore, according to the prior art, the start of a direct-injection internal combustion engine generally proceeds without the inclusion of the current pressure prevailing in the high-pressure region.
  • In order to increase the accuracy of the pressure sensor 7, the invention proposes a method for calibrating the pressure sensor 7, in which a low pressure prevailing in the high-pressure region HD is used as the reference pressure. The reference pressure is with a high accuracy known or can be determined or measured with high accuracy. The low pressure prevailing in the high-pressure region is also measured as the sensor pressure by the pressure sensor 7. After measuring the sensor pressure by the pressure sensor 7 is checked whether the measured sensor pressure is within predetermined plausibility limits. The characteristic of the pressure sensor 7 is then corrected so that the difference between the reference pressure and the sensor pressure is minimized.
  • There are a variety of ways to determine the reference pressure with a higher accuracy than the sensor pressure can be measured. As a reference pressure, for example, the ambient pressure can be used. Furthermore, the low pressure prevailing in the high-pressure accumulator 4 can also be generated by the prefeed pump 1. For this purpose, the prefeed pump 1 of the fuel metering system is activated. It generates a form in the low-pressure area ND. The admission pressure is led from the low-pressure area ND into the high-pressure area HD by opening the inlet valves and the outlet valves of the high-pressure pump 2. The pressure set at the low-pressure regulator 13 of the fuel metering system in the low-pressure region ND is then used as the reference pressure, taking into account the opening pressure of the inlet valves and outlet valves of the high-pressure pump 2.
  • The low pressure regulator 13 of the fuel metering system has an accuracy of about ± 6%, which corresponds to a pre-pressure of about 4 bar ± 240 mbar. The inlet and outlet valves of the high-pressure pump 2 also have an accuracy of about ± 6%, so that the reference pressure can be determined with an accuracy of at least ± 500 mbar. In one in a fuel metering system of a direct injection gasoline engine used high pressure sensor 7 with a measuring range of about 150 bar, this corresponds to an accuracy of about ± 0.3%. With such a high accuracy, the sensor pressure can not be determined by the pressure sensor 7.
  • It is also conceivable that the reference pressure is measured by a high-precision low-pressure sensor (not illustrated) arranged at least at times in the high-pressure region HD. Such a low-pressure sensor can be introduced for measuring the low pressure in the high-pressure accumulator 4 and removed again after the measurement.
  • The method is preferably performed automatically during the starting process of the internal combustion engine after switching on the ignition and before the activation of the starter. Although during this time the prefeed pump is activated, however, no high pressure is generated in the high-pressure area HD. The intake valves and exhaust valves of the high pressure pump 2 are üblichicherweise designed as passive valves. By opening the inlet valves and the outlet valves of the high-pressure pump 2, the admission pressure is directed into the high-pressure accumulator.
  • Alternatively, the method can also be carried out automatically during the after-running of the internal combustion engine after switching off the internal combustion engine and before switching off the ignition. During the caster, the ignition is still switched on and the control unit 8 drives down the various functions of the motor vehicle in a controlled manner. To carry out the process during the overrun, the prefeed pump 1 must be specifically controlled; and the intake valves and the exhaust valves of the high-pressure pump 2 must be open.
  • The inventive method is preferably according to the Assembly or after a repair of the fuel metering system of the internal combustion engine, in particular after replacement of the pressure sensor 7, carried out.
  • It is also conceivable to carry out the method according to the invention during operation of the internal combustion engine. For this purpose, for example, the opening pressure of the pressure control valve 11 of the fuel metering system in a specific operating state of the internal combustion engine can be used as the reference pressure.
  • The pressure control valve 11 is normally closed with spring load. The pressure control valve 11 is therefore closed without electrical control and opens at a predetermined opening pressure. The opening pressure may depend on environmental parameters such as engine speed, mass flow through the pressure control valve 11, ambient temperature, etc., but is generally known to be relatively accurate in certain operating conditions. For example, e.g. in directly injecting gasoline internal combustion engines at idle speed, the opening pressure of the pressure control valve 11 with an accuracy of about ± 2.5 bar known. The inaccuracies of the pressure sensor 7 of the fuel metering system are usually much higher. If, during operation of the internal combustion engine at idle speed, the pressure control valve 11 opens, it can be assumed that in the high-pressure accumulator 4, a pressure prevails, which corresponds approximately to the opening pressure of the pressure control valve 11. This pressure is then used as the reference pressure for the adaptation of the sensor characteristic.
  • The inventive method in FIG. 1 begins in function block 20. In a subsequent function block 21 the ignition of the motor vehicle is turned on. In a function block 22, the prefeed pump 1 is activated, and in a functional block 23, the inlet valves and outlet valves of the high-pressure pump 2 are opened. In a functional block 24, the reference pressure prevailing in the high-pressure accumulator 4 is read from a memory of the control unit 8. The reference pressure was determined in advance from the pressure set at the low-pressure regulator 13 taking into account the opening pressure of the intake valves and exhaust valves of the high-pressure pump 2 and stored in the memory.
  • In a functional block 25, the pressure prevailing in the high-pressure accumulator 4 is then measured by the pressure sensor 7. The stored in the memory of the controller 8 characteristic of the pressure sensor 7 is read in a function block 26. In a function block 27, the read-in characteristic curve of the pressure sensor 7 is shifted such that the difference between the reference pressure and the sensor pressure is minimized. The corrected characteristic is then stored in a function block 28 in the memory of the controller 8. In a functional block 29, the inventive method is then completed.
  • The control of the internal combustion engine by the control unit 8 is then based on the corrected characteristic of the pressure sensor 7. The pressure sensor 7 now has such a high accuracy that the pressure prevailing in the high-pressure accumulator 4 pressures during the start phase (with the then in the high-pressure accumulator 4th prevailing low pressures) can be included in the calculation of the injection time of the injectors 5.

Claims (8)

  1. Method for calibrating a pressure sensor (7) of a fuel metering system of an internal combustion engine, with the fuel metering system having a high-pressure pump (2) for feeding fuel from a low-pressure region (ND) into a high-pressure region (HD), having injectors (5), which can be activated in a manner dependent on characteristic operating variables, for metering the fuel from the high-pressure region (HD) into combustion chambers (6) of the internal combustion engine, and having the pressure sensor (7) for measuring the pressure in the high-pressure region (HD), with a pressure prevailing in the high-pressure region (HD) being determined as a reference pressure, with the pressure prevailing in the high-pressure region (HD) being measured by the pressure sensor (7) as a sensor pressure, and with the difference between the reference pressure and sensor pressure being formed, characterized in that a pressure is generated in the high-pressure region (HD) by virtue of a prefeed pump (1) of the fuel metering system being activated so as to generate a pressure in the low-pressure region (ND), and with the pressure being conducted from the low-pressure region (ND) into the high-pressure region (HD) and being taken into consideration as a reference pressure, with the characteristic curve of the pressure sensor (7) being corrected in such a way that the difference between the reference pressure and sensor pressure is minimized.
  2. Method according to Claim 1, characterized in that, after the measurement of the sensor pressure by the pressure sensor (7) and before the correction of the characteristic curve of the pressure sensor (7), it is checked whether the measured sensor pressure lies within predefined plausibility constraints.
  3. Method according to Claim 1 or 2, characterized in that the pressure is conducted from the low-pressure region (ND) through open inlet valves and outlet valves of the high-pressure pump (2) into the high-pressure region (HD), with the pressure which is set in the low-pressure region (ND) at a low-pressure regulator of the fuel metering system being taken into consideration, allowing for the opening pressure of the inlet valves and outlet valves of the high-pressure pump (2), as a reference pressure.
  4. Method according to Claim 1 or 2, characterized in that the reference pressure is measured by a high-precision low-pressure sensor which is arranged in the high-pressure region (HD) at least intermittently.
  5. Method according to one of Claims 1 to 4,
    characterized in that the method is carried out automatically during the starting process of the internal combustion engine after the ignition is switched on and before the starter is activated.
  6. Method according to one of Claims 1 to 5,
    characterized in that the method is carried out automatically during the run-down of the internal combustion engine after the internal combustion engine is shut down and before the ignition is switched off.
  7. Method according to one of Claims 1 to 6,
    characterized in that the method is carried out after the assembly of or after a repair to the fuel metering system of the internal combustion engine, in particular after an exchange of the pressure sensor (7).
  8. Device for calibrating a pressure sensor (7) of a fuel metering system of an internal combustion engine, with the fuel metering system having a high-pressure pump (2) for feeding fuel from a low-pressure region (ND) into a high-pressure region (HD), having injectors (5), which can be activated in a manner dependent on characteristic operating variables, for metering the fuel from the high-pressure region (HD) into combustion chambers (6) of the internal combustion engine, and having the pressure sensor (7) for measuring the pressure in the high-pressure region (HD), characterized in that the device has means for carrying out the method according to one of Claims 1 to 7.
EP20010911382 2000-01-29 2001-01-24 Method and device for calibrating a pressure sensor Expired - Fee Related EP1255926B1 (en)

Priority Applications (3)

Application Number Priority Date Filing Date Title
DE10003906 2000-01-29
DE2000103906 DE10003906A1 (en) 2000-01-29 2000-01-29 Fuel dosing system pressure sensor calibrating process, involving using pressure in high-pressure zone as reference pressure
PCT/DE2001/000271 WO2001055573A2 (en) 2000-01-29 2001-01-24 Method and device for calibrating a pressure sensor

Publications (2)

Publication Number Publication Date
EP1255926A2 EP1255926A2 (en) 2002-11-13
EP1255926B1 true EP1255926B1 (en) 2009-07-29

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EP20010911382 Expired - Fee Related EP1255926B1 (en) 2000-01-29 2001-01-24 Method and device for calibrating a pressure sensor

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US (1) US6802209B2 (en)
EP (1) EP1255926B1 (en)
JP (1) JP4791671B2 (en)
DE (2) DE10003906A1 (en)
ES (1) ES2328105T3 (en)
RU (1) RU2260142C2 (en)
WO (1) WO2001055573A2 (en)

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RU2002121651A (en) 2004-03-10
JP4791671B2 (en) 2011-10-12
DE10003906A1 (en) 2001-08-09
EP1255926A2 (en) 2002-11-13
ES2328105T3 (en) 2009-11-10
US6802209B2 (en) 2004-10-12
JP2003535313A (en) 2003-11-25
DE50115013D1 (en) 2009-09-10
RU2260142C2 (en) 2005-09-10
WO2001055573A2 (en) 2001-08-02
US20030046990A1 (en) 2003-03-13
WO2001055573A3 (en) 2002-02-14

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