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
  • F02D41/30—Controlling fuel injection
  • F02D41/38—Controlling fuel injection of the high pressure type
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
  • F02D—CONTROLLING COMBUSTION ENGINES
  • F02D41/00—Electrical control of supply of combustible mixture or its constituents
  • F02D41/24—Electrical control of supply of combustible mixture or its constituents characterised by the use of digital means
  • F02D41/2406—Electrical control of supply of combustible mixture or its constituents characterised by the use of digital means using essentially read only memories
  • F02D41/2425—Particular ways of programming the data
  • F02D41/2429—Methods of calibrating or learning
  • F02D41/2432—Methods of calibration
  • F02D41/2435—Methods of calibration characterised by the writing medium, e.g. bar code
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
  • F02D—CONTROLLING COMBUSTION ENGINES
  • F02D41/00—Electrical control of supply of combustible mixture or its constituents
  • F02D41/24—Electrical control of supply of combustible mixture or its constituents characterised by the use of digital means
  • F02D41/2406—Electrical control of supply of combustible mixture or its constituents characterised by the use of digital means using essentially read only memories
  • F02D41/2425—Particular ways of programming the data
  • F02D41/2429—Methods of calibrating or learning
  • F02D41/2451—Methods of calibrating or learning characterised by what is learned or calibrated
  • F02D41/2464—Characteristics of actuators
  • F02D41/2467—Characteristics of actuators for injectors

Definitions

• the invention relates to electronically controlled multi-point injection devices for an internal combustion engine and more particularly to an injection module belonging to such a device and comprising a ramp intended to be connected to a supply pump and more several injectors connected to the ramp and each provided with electrically controlled opening and closing means.
• the injectors are manufactured to meet a nominal characteristic that is desired to be linear.
• Figure 1 shows in thick lines a nominal characteristic that can be considered representative.
• the quantity injected, at a constant pressure difference between the supply and the combustion chamber, is a substantially linear function of the opening time. In practice, manufacturing tolerances cause dispersions, especially for short injection times.
• the fine line curve in Figure 1 shows an example of a real characteristic.
• the injectors must have a characteristic whose deviation from the setpoint characteristic does not exceed a determined percentage, for example +/- 5%. To fulfill this condition, each injector manufactured is subjected to bench tests and, by trial and error, the preload of the closing spring is sought which makes it possible to get as close as possible to the set characteristic. These are long operations which only allow to compensate for limited deviations, since we act globally on the characteristic.
• the present invention aims to provide an injection module making it possible to tolerate relatively large dispersions of the characteristics of the injectors.
• the invention proposes in particular an injection module comprising means for storing a calibration function of each of the injectors and providing said function in a form usable by a calculation unit controlling the duration of the electrical opening command of the injectors.
• the function to be memorized is determined automatically, by reading the quantities injected for a given number of determined opening times distributed over the operating dynamics. This function can then be stored in the form of a polynomial of sufficient degree or in cartographic form.
• the injection of fuel into a chamber is carried out under a differential pressure which varies according to the operating parameters of the engine.
• This situation can be taken into account by using a cartographic model with two inputs (injection time and differential pressure) or by using a polynomial with two variables. Since the calibration can be carried out automatically, the only manual operations being the installation of the injector and its removal, it is possible to accept a very large number of measurement points, with durations of injection can vary within a very wide range, for example from 0.15 ms up to 10 ms. The main variable being the duration of injection, it will suffice to carry out tests for 2 or 3 different differential pressures, on an automatic test bench.
• the memorized model must accompany the injector and be taken into account in its order by the calculation unit.
• the model is stored in a complete module comprising the injection manifold and the injectors which are permanently attached to it, for example, in a read only memory.
• the module can then be provided with a connector for connection with the calculation unit and with the power amplifier which is controlled by this calculation unit and opens the injectors.
• the connector is provided with a contact or contacts making it possible to copy models representative of the correction with respect to the nominal characteristic, with a view to copying in the calculating member.
• the latter can then be programmed to take into account the corrections over each nominal actuation duration, to take account of the real characteristic of each injector.
• the module will generally also include a pressure sensor providing an electrical output signal representative of the injection pressure prevailing in the boom.
• the calculation unit is connected to this sensor and also to a sensor giving the pressure at the intake of the combustion chambers, representative of the pressure which prevails in these chambers during injection.
• the calculation unit can then take into account not only the model representative of the real characteristic as a function of the nominal injection duration, but also the corrections to be made as a function of the differential injection pressure.
• the pressure sensors will generally be piezoresistive sensors, which have the robustness required to have a long service life under the operating conditions of an internal combustion engine. The above characteristics as well as others will appear better on reading the following description of a particular embodiment of the invention, given by way of nonlimiting example.
• FIG. 1 shows an example of variation of the quantity of fuel injected as a function of the duration of injection.
• FIG. 2 shows an example of correction ⁇ t to be performed over the injection duration as a function of the injection time, for several differential pressures p;
• Figure 3 is a perspective view of a module for implementing the invention;
• Figure 4 is a block diagram showing hardware and software components involved in the implementation artwork .
• FIG. 2 shows three functions corresponding to three different values of the differential pressure.
• These calibration functions can be stored in digital form in several different ways.
• a first solution consists in sampling each of the curves, possibly after smoothing, and in memorizing the sampled points for each of the three differential pressures. This gives a cartographic memory. It can be used either by making a correction corresponding to the nearest stored point, or by bilinear interpolation. The complexity of this latter solution, however, makes it unattractive because the corrections made are always relatively small.
• the curves can also be stored in the form of a polynomial with two variables, which gives better continuity than a cartographic memory, or of several polynomials as a function of time corresponding to several differential pressures.
• the module shown diagrammatically in FIG. 3 comprises an injection ramp 10 to which four electrically controlled injectors 12 are connected.
• the rail is provided with a fuel supply connector 14, connected to a high pressure pump, possibly by a regulator.
• Each injector is provided with an electrical connector 16 for connection to conductors contained in a strip 18 provided with a terminal electrical connector 20.
• the module has a non-volatile memory in which the calibration function is loaded. In general, this memory will only be accessible in read mode from a contact of connector 20. However, it is possible to provide a memory that can be rewritten for recalibration after using the module.
• the content of the module memory is provided to be transferred to the memory of an engine control computer at the end of the vehicle integration line. In an alternative embodiment, the module can simply be accompanied by a memory whose content is transferred to the computer at the end of the integration line.
• the module is completed by a pressure sensor, for example piezoelectric, which can be connected to a nozzle 22.
• a second sensor (not shown) is then provided to determine the pressure in the combustion chambers.
• the essential components which are involved in the implementation of the invention are indicated in FIG. 4.
• the functions in the dashed line frame s24 will generally be fulfilled by the engine control computer, into which the function stored in memory 26 is transferred. that accompanies the module.
• the computer 24 can be viewed as having a block 27 for managing the fuel supply to the engine, which receives the operating parameters, such as the position ⁇ of the accelerator pedal, the speed N, the temperature ⁇ , etc. ...
• the block 27 can in particular develop a setpoint pressure PO of the fuel (dashed arrow in FIG. 4).
• this setpoint pressure PO can equally well be produced by a separate element 28, depending for example on the pressure in the combustion chambers at the start of the exhaust.
• the pressure in the ramp 10 is measured by a sensor 30.
• An error term is generated in an adder 32 and supplied to a regulator 34 supplying the ramp 12.
• Block 27 provides a quantity q setpoint to be injected into a correction block 28 in which the calibration function, which may be the actual law of variation, is loaded.
• the block 28 shown receives an output signal from the sensor 30 on an input 34.
• the correction as a function of the pressure can be carried out in this block or in an additional block 36 which receives the output of a pressure sensor in the combustion.
• the pressure in the ramp can be applied to an input 38 in the event that the corrections as a function of the duration and as a function of the differential pressure are carried out in cascade.
• the corrected duration signal is applied to a power circuit 40 for controlling the injectors 12.

Landscapes

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

Applications Claiming Priority (3)

Publications (2)

Family

ID=9523405

Family Applications (1)

Country Status (6)

Families Citing this family (18)

Family Cites Families (12)

• 1998
  • 1998-02-26 FR FR9802345A patent/FR2775318B1/fr not_active Expired - Fee Related
• 1999
  • 1999-02-24 WO PCT/FR1999/000412 patent/WO1999043940A1/fr active IP Right Grant
  • 1999-02-24 BR BR9904895-7A patent/BR9904895A/pt not_active IP Right Cessation
  • 1999-02-24 EP EP99904943A patent/EP0979350B1/de not_active Expired - Lifetime
  • 1999-02-24 US US09/403,415 patent/US6247451B1/en not_active Expired - Lifetime
  • 1999-02-24 DE DE69906642T patent/DE69906642T2/de not_active Expired - Lifetime

Non-Patent Citations (1)

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