Classifications

• • 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
  • F02D41/20—Output circuits, e.g. for controlling currents in command coils
  • F02D41/2096—Output circuits, e.g. for controlling currents in command coils for controlling piezoelectric injectors
• • 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
  • F02D41/22—Safety or indicating devices for abnormal conditions
• • 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
  • F02D41/20—Output circuits, e.g. for controlling currents in command coils
  • F02D2041/202—Output circuits, e.g. for controlling currents in command coils characterised by the control of the circuit
  • F02D2041/2051—Output circuits, e.g. for controlling currents in command coils characterised by the control of the circuit using voltage control
• • 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
  • F02D41/20—Output circuits, e.g. for controlling currents in command coils
  • F02D2041/2086—Output circuits, e.g. for controlling currents in command coils with means for detecting circuit failures
  • F02D2041/2089—Output circuits, e.g. for controlling currents in command coils with means for detecting circuit failures detecting open circuits

Definitions

• the invention relates to a method and an arrangement for diagnosing a load drop for a piezoelectric actuator of a single-point arrangement as well as a computer program and a computer program product.
• An injection assembly or an injection system which is also referred to as a common rail system, for internal combustion engines is adapted to introduce fuel into a combustion chamber of an internal combustion engine.
• the injection arrangement as an actuator for acting on an injection valve, for example.
• a diagnosis of the load drop is provided via the power stage module CY372, but this diagnosis only works in certain control unit configurations.
• the document EP 1 138 905 B1 describes a method for detecting a load decrease in the driving of piezoelectric elements in order to reliably detect a drop in the electrical load of one or more of the piezoelectric elements.
• a load drop of a piezoelectric element is detected by monitoring whether a desired voltage is reached on the piezoelectric element in less than a predetermined minimum time. When such a voltage is reached in less than the minimum time, a signal is generated to indicate that a load drop has occurred for that piezoelectric element.
• Such a signal can be initiated countermeasures that may be necessary for troubleshooting. The troubleshooting can be done, for example, in the workshop.
• the signal may also be used to store an error message in an electronic memory.
• the invention relates to a method for diagnosing a load drop at a piezo actuator in an injection arrangement or an injection system in an internal combustion engine.
• a voltage applied to the piezoelectric actuator is measured and compared with a threshold voltage.
• the load drop to be diagnosed is then present if the measured voltage is greater than the threshold voltage.
• the method is suitable, for example, for injection arrangements which are designed as so-called common rail injection arrangements.
• Such injection arrangements also have piezo actuators, which are correspondingly designed as C R piezostats.
• the piezoelectric actuators are provided to act on a valve module of an injection valve of the injection assembly to actuate an injection process and thereby actuate, thereby opening the injection valve and filling fuel into a combustion chamber of the internal combustion engine.
• common rail injection arrangements it is provided that pressure generation and injection of the fuel are temporally and locally decoupled. In this case, the injection pressure is generated by a separate high-pressure pump, which does not necessarily have to be driven in synchronism with the injection processes.
• the threshold voltage provided for comparison can be provided automatically and / or dynamically as a function of an operating point of the injection arrangement.
• the threshold voltage is formed from a sum of a setpoint voltage U S ⁇ ⁇ plus an offset voltage .DELTA.U.
• the setpoint voltage Us o ii as a first summand for the threshold voltage is typically dependent on an operating parameter of the injection arrangement, for example on a pressure of a fuel in the injection arrangement. To implement the Method can therefore be determined by a control unit of this pressure and thus monitored, so that it is possible to adjust the setpoint voltage U S ⁇ ⁇ operatively associated and thus provide for performing an embodiment of the method.
• the offset voltage .DELTA.U as a second summand for the threshold voltage can also be chosen application-related and / or operating-accompanying.
• a value for the offset voltage .DELTA.U can for this purpose also be provided by the control unit during operation on the basis of operating parameters. Accordingly, the threshold voltage is dependent on at least one operating parameter of the injection arrangement, for example the pressure of the fuel.
• the voltage to be measured during the process is measured at the earliest from the end of a charging process for loading the piezoelectric actuator during an injection process. Usually, this voltage is measured after the charging process, typically directly after completion of the charging process.
• the to be diagnosed in a variant of the method load drop of the piezoelectric actuator may have different causes.
• diagnosing the load drop it is, for example, possible to detect an interruption in a wiring harness via which the piezoelectric actuator is supplied with electrical energy starting from the control unit, within the injection arrangement.
• an interruption which is usually longer than a so-called. WackelCAM, within at least one line to which the piezoelectric actuator is connected to the control unit.
• the method can also detect load drops that have other causes.
• the invention further relates to an arrangement for diagnosing a load drop on a piezoelectric actuator in an injection arrangement.
• This arrangement is designed to measure a voltage and further to compare this measured voltage with a threshold voltage.
• the arrangement is to diagnose a presence of a load drop, if the measured voltage is greater than the threshold voltage.
• this arrangement can have a control unit or an engine control unit for an injection arrangement. It may also be provided that the Order a bank voltage measuring bridge, which is designed to measure the voltage has. In this regard, it can be provided that said bank voltage measuring bridge is designed as a component of the control unit.
• the assembly typically the controller as a component of the assembly, is configured to cooperate with the injector assembly to thereby control and thus control and thus control injection events to be performed by the injector assembly, whether or not there is load dumping to regulate.
• the relative threshold diagnostics provided in the invention are at a setpoint and not, as in previous approaches, with absolute values that are typically predetermined.
• the detection probability of a fault in a load drop can be significantly increased while the robustness against misdiagnosis can be increased.
• the new diagnostic function can be set application-specific or applicative, whereas previous approaches offer no possibility for such an adaptation.
• the arrangement described is designed to carry out all the steps of the presented method.
• individual steps of the method can also be carried out by individual components of the arrangement.
• functions of the arrangement or functions of individual components of the arrangement can be implemented as steps of the method.
• the invention further relates to a computer program with program code means in order to perform all the steps of a described method when the computer program is executed on a computer or a corresponding arithmetic unit, in particular in an arrangement according to the invention.
• the computer program product according to the invention with program code means which are stored on a computer-readable data carrier is designed to carry out all the steps of a described method when the computer program is executed on a computer or a corresponding arithmetic unit, in particular in an arrangement according to the invention.
• the load-drop diagnostics function assumes that there is no detection through the application-specific integrated circuit (ASIC), and as a result, note charging does not occur. In the context of the invention, it can either be provided that a recognition by the ASIC is or will be disabled, or that this does not work.
• ASIC application-specific integrated circuit
• the load drop can be diagnosed by the control unit and thus detected, it is possible that measures can be taken to remedy the load drop, starting from the control unit.
• the voltage increases up to the maximum value of the buffer voltage U Buff e r and remains at this level until the output stage ends the charging process at a second time. Then the voltage drops again.
• a voltage measurement is performed in an embodiment of the method. A thereby determined voltage measurement or measured value for the voltage is compared with the threshold voltage, which is the voltage offset U above the setpoint voltage U S ⁇ ⁇ . If the voltage reading is above the voltage threshold Us o ii + U, the load drop is detected. As the nominal voltage typically is dependent on the rail pressure, the threshold shifts automatically to an operating point of the injection assembly.
• the function provided in the context of the invention is realized in a measurement of the voltage curve at a load drop in the control unit and a corresponding diagnostic reaction.
• FIG. 1 shows a schematic representation of a first diagram of voltage curves.
• FIG. 2 shows a schematic diagram of a second voltage curve.
• FIG. 3 shows a schematic representation of an embodiment of an arrangement according to the invention.
• the diagram shown in Figure 1 comprises a vertically oriented axis 2 for a voltage plotted against a horizontally oriented axis 4 for the time.
• a first voltage curve 6 (solid line) and a second voltage curve 8 (dashed line) are shown.
• a first time 10 (solid line)
• a second voltage curve 8 (dashed line)
• a first time 10 is indicated.
• a second time 12 is shown.
• a third time 14 and a fourth time 16 are indicated.
• a value for a target voltage 18 Usoii and a value for a buffer voltage 20 U Buff e r is indicated.
• the first voltage curve 6 shows a typical charging curve in a faultless injection arrangement.
• the charging process for a piezo actuator of the injection assembly begins. This charging process lasts until the second time point 12. The voltage then drops slightly until a third point in time 14, from which the unloading process begins. In this time, the target voltage 18 U S ⁇ ⁇ should be achieved in the adjusted state.
• the discharging process is completed at a fourth time 16 when a voltage of 0 V is reached.
• the second voltage curve 8 in the diagram of Figure 1 is obtained when a load drop occurs at the piezoelectric actuator, which is caused by an interruption of a supply of electrical energy to the piezoelectric actuator.
• the result is that the voltage increases steeper than in the fault-free case and also reaches a much higher value than in the fault-free case.
• a voltage measurement 22 is carried out when a configuration of the method according to the invention is carried out at a fifth time after the second time 12.
• One to this fifth time measured value is compared with the value for a threshold voltage 24.
• the value for the threshold voltage 24 results from a sum of the setpoint voltage 18 U S ⁇ ⁇ and an offset voltage 26 .DELTA.U. It is provided, inter alia, that the setpoint voltage 18 U S ⁇ ⁇ depends on a pressure of a fuel within the injection arrangement. Accordingly, the value for the threshold voltage 24 depends on this pressure. In an embodiment of the method, therefore, the threshold voltage 24 is adapted to a current operation of the injection assembly.
• a condition that speaks for the presence of the load drop at the piezoelectric actuator is that the voltage measured at the fifth time point is greater than the threshold voltage 24. If the voltage measured at the fifth time is less than the threshold voltage 24, no load drop is diagnosed as part of the method.
• the second voltage waveform 8 shown in the diagram of FIG. 1, which occurs in the event of a defect, is measured at a bank voltage measuring bridge in the control unit.
• the diagram of Figure 2 shows a circled in the diagram of Figure 1 detail of the diagram of Figure 1, wherein a third voltage waveform 28 (dotted line) is shown in addition.
• This third voltage waveform 28 is measured by an application specific integrated circuit (ASIC) of the controller in the presence of a load drop.
• ASIC application specific integrated circuit
• the third voltage waveform 28 (dotted line) of the detection mechanism is represented by the ASIC in the case of load drop. Since the piezo actuator is no longer connected due to the interruption, only the parasitic capacitances of the final stage of the control unit are charged. Since these are very small, the voltage at the preset current increases very much. If a second voltage threshold uTOMin 32 is exceeded within a time interval T_uT0Min 30, the ASIC detects the load drop. This is followed by an immediate discharge and a corresponding message to the CPU or a main processor via an SPI or serial peripheral interface. However, due to electromagnetic compatibility (EMC) measures, parasitic capacitances may be so great in certain controller configurations that the voltage increase is not fast enough.
• EMC electromagnetic compatibility
• the detection by the ASIC fails.
• the voltage increases until reaching the maximum available buffer voltage 20 Ussu ff e r and remains at this level until the charging switch is opened at the second time 12. Due to the transfer inductance, the voltage then drops slightly more initially and then remains at a high level until the discharge process. In this case, the diagnosis of the load drop takes place with the method described by FIG.
• FIG. 2 shows a schematic illustration of an embodiment of an arrangement 40 according to the invention for a so-called common rail injection arrangement or a common rail injection system for an internal combustion engine.
• This arrangement 2 comprises a piezoelectric actuator 42, which is designed to act on a valve needle of the injection assembly.
• This piezo actuator 42 is connected in series with a harness resistor 44.
• the piezoelectric actuator 42 and the harness resistor 44 are connected via two electrical lines 46, 48 to a positive pole 50 and a negative pole 52 of a first control device component 54 of a control device 56 as a further component of the arrangement 40.
• the control unit 56 is designed to supply the piezoelectric actuator 42 with electrical energy via the electrical lines 46, 48, so that a voltage is applied to the piezoelectric actuator 42 during ideal operation, which makes it possible to use an injection valve to carry out a Inject injection process.
• the control unit 56 shown schematically has, as a further controller component 58, a bank voltage measuring bridge which is designed to measure the voltage which is applied to the piezoelectric actuator 42.

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• Engineering & Computer Science (AREA)
• Chemical & Material Sciences (AREA)
• Combustion & Propulsion (AREA)
• Mechanical Engineering (AREA)
• General Engineering & Computer Science (AREA)
• Fuel-Injection Apparatus (AREA)
• Combined Controls Of Internal Combustion Engines (AREA)
• Electrical Control Of Air Or Fuel Supplied To Internal-Combustion Engine (AREA)

Applications Claiming Priority (2)

Publications (1)

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• 2008
  • 2008-05-26 DE DE102008001971A patent/DE102008001971A1/de not_active Withdrawn
• 2009
  • 2009-04-22 US US12/736,848 patent/US20110140685A1/en not_active Abandoned
  • 2009-04-22 WO PCT/EP2009/054791 patent/WO2009144099A1/de active Application Filing
  • 2009-04-22 KR KR1020107026391A patent/KR101571918B1/ko not_active IP Right Cessation
  • 2009-04-22 CN CN200980118929.1A patent/CN102046950B/zh not_active Expired - Fee Related
  • 2009-04-22 JP JP2011510922A patent/JP5175386B2/ja not_active Expired - Fee Related
  • 2009-04-22 EP EP09753754A patent/EP2294302A1/de not_active Withdrawn

Non-Patent Citations (2)

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