FR3060744A1 - METHOD FOR DETERMINING THE INJECTION RATE OF AN INJECTOR OF A FUEL ASSAY SYSTEM FEEDING A VEHICLE INTERNAL COMBUSTION ENGINE - Google Patents

Abstract

A method for determining an injection dose of an injector (18) in which the internal combustion engine (10) is coupled to an electric machine (40) for transmitting torque. When the vehicle is stopped, the engine (10) operates at a certain predetermined speed (n) and under a predefined load and the current (1) generated by the electric machine (40) is determined, and from the intensity of the current (1) generated by the electrical machine (40) the injection dose (m) of the injector (18) is fixed.

Description

Holder (s): ROBERT BOSCH GMBH.

Extension request (s)

Agent (s): CABINET HERRBURGER.

METHOD FOR DETERMINING THE INJECTION DOSE OF AN INJECTOR OF A FUEL DOSING SYSTEM SUPPLYING A VEHICLE INTERNAL COMBUSTION ENGINE.

FR 3 060 744 - A1 (5 /) Method for determining an injection dose of an injector (18) according to which the internal combustion engine (10) is coupled to an electric machine (40) to transmit a torque.

When the vehicle is stopped, the motor (10) operates at a certain predetermined speed of rotation (n) and under a predefined load and the current (1) generated by the electric machine (40) is determined, and from l intensity of the current (1) generated by the electric machine (40), the injection dose (m) of the injector (18) is fixed.

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Field of the invention

The present invention relates to a method for determining the injection dose of at least one fuel metering system injector of an internal combustion engine of a vehicle as well as a calculation unit and a computer program for the implementation of this process.

State of the art

Fuel metering systems make it possible to dose the fuel necessary for combustion in an internal combustion engine, the fuel being injected by one or more injectors. In the case of direct petrol injection and in the case of common rail injection, the fuel is injected directly into the combustion chamber. The quantity of fuel dosed accurately is a decisive factor for the quality of combustion and thus the consumption and the combustion gases emitted by the internal combustion engine.

However, the quantity of fuel dosed is itself influenced by the properties of the injector. Due to the dispersion of the copies, in the case of injectors used in an internal combustion engine, the fuel dose allocated to the different injectors is often different to have an identical control, which results in a reduction in the quality of combustion. It should also be noted that not all engine cylinders and with the same control generate the same torque. The consequence of the differences in torque is the irregular operation of the engine and the increase in its emissions.

We can verify by a speed up test, the quantitative difference related to the injectors installed in an internal combustion engine, even in the case of a vehicle delivered to the customer, and this in a simple way without requiring disassembly. The specific conditions of the workshop environment allow modified operating modes as well as fixed and stable operating points. In normal driving, this is often not possible because the control unit of the internal combustion engine must apply the driver's request. Differents injected quantities 3060744 rents can be detected at the increase in speed of the internal combustion engine in that starting from a certain idle rotation speed, by predefining a set dosage quantity for all injectors except for one d 'between them, will be accelerated for a fixed period (that is to say a speed increase). This neutralizes the precision, balancing and correction functions with previously learned values, if necessary, to recognize as clearly as possible the actual operating state. The target rotation speed then obtained is measured. We change the injector not ordered. If one or more target rotation speeds vary significantly from the average of the other target rotation speeds, this leads to the conclusion that there is a deviation from the actual injection dose compared to the set dose.

But this has the disadvantage of having only a reduced speed range in which the injectors only provide a small part of their usual dose. In this quantitative range, possible faults which have repercussions especially for a large quantity of dosage do not have enough repercussions to be detected.

Document DE 10 2009 028 374 A1 describes a method according to which, for adapting or diagnosing an internal combustion engine associated with a hybrid vehicle and which constitutes a power unit, with at least one secondary engine, for regulating the different operating states of the internal combustion engine by the secondary engine to have a positive or negative reaction torque applied to the internal combustion engine which is operated with a parameter at a set operating point.

Presentation and advantages of the invention

The invention relates to a method for determining an injection dose of at least one fuel metering system injector of a vehicle internal combustion engine according to which the internal combustion engine is coupled to an electric machine for transmit a torque, the current generated by the electric machine when the vehicle is stopped is determined, the internal combustion engine operating at a certain predefined rotation speed and under a predefined load, and the injection dose of a injector from the value of the current generated by the electric machine.

The invention consists in providing the load applied to an internal combustion engine by an electric machine coupled to the internal combustion engine in the direction of the torque transmission. The electric current generated by the electric machine for a determined speed of rotation of the internal combustion engine is thus a measure of the quantity of fuel actually used. Electric hybrid drive machines are particularly suitable because these machines are usually relatively powerful and can therefore operate at high load points. However, it is also possible to envisage other electrical machines, for example, those intended for dynamic operation (operation by energy recovery) or used in on-board networks at 48V. The present invention makes it possible in particular to directly judge the energy supplied to the engine by the exploitation of the energy balance of the electric machine.

The invention makes it possible to check the injectors and in particular to locate a faulty injector in the workshop in that the load point of the internal combustion engine is shifted for a fixed speed of rotation, towards the high loads at idle. For this, it is important to have an electric machine which can apply a load to the internal combustion engine and thus allow it to use a higher dose of fuel, to prevent the internal combustion engine from going into overspeed and n '' reaches too high a rotation speed. From the current generated by the electric machine we can then conclude with the quantity injected.

We will also be able to control the actuators that influence the energy emitted by the internal combustion engine, such as the exhaust gas return valve, the throttle valve, the inertia valve, the check valve, the turbocharger. Or other. For example, the opening and closing of the exhaust gas recirculation valve can be used to modify the energy supplied by the internal combustion engine and thus modifying the intensity of the current which can be exploited. . The same applies to a turbocharger or other actuator. This makes it possible to diagnose faults (for example) of a seized actuator.

Preferably, before determining the injection dose, in particular already from the start of loading, it is checked whether certain release conditions are met. These include checking the state of charge of the battery supplied by the electric machine to determine its maximum state of charge. The battery must indeed be able to absorb the energy supplied by the electric machine. It is also advantageously a question of verifying the electrical functioning of the components of the internal combustion engine. If one of the release conditions is not met, the load will not be released. It is intended to achieve the release condition actively, for example, by discharging the battery. Preferably, the load is released when the release conditions are met.

Preferably, before determining the injection dose, in particular already before the start of loading, the functions which can influence the result of the test are blocked or cut. This is, for example, the regeneration function of the particulate filter or catalyst.

Preferably, before determining the injection dose, the internal combustion engine is operated in a defined operating state. It is a question of predefining a speed of rotation. Preferably, this also consists in predefining at least one parameter chosen between the pressure of the high pressure fuel accumulator (common rail), the position of the exhaust gas recycling valve, the position of the flap throttle, the defined position of the turbocharger actuator and the like. In this way we will have a comparable result.

Preferably, before determining the injection dose, the doses or the torque associated with the injectors are balanced so that each injector provides practically the same torque component. For example, according to the documents DE 195 27 218 Al DE 2004 010 412 Al, there are known methods of balancing cylinders (also called operating regulation procedure) which, among other things, are known under the name (FBC) Fuel Balance Control. According to these procedures, using sensor installations, the instantaneous speed of the internal combustion engine is entered and the change in the speed entered is analyzed. This makes it possible to determine the variations in torque and to conclude from the variations in the mass of fuel injected into the different cylinders of the internal combustion engine. The differences between the masses of fuel injected can then be compensated for by correcting the target injection mass by applying a mass correction.

A calculation unit according to the invention, for example, the vehicle control device or a test device used in the workshop, makes it possible in particular to execute the method according to the invention in the form of a program.

The method can also be implemented in the form of a computer program, which is advantageous because, in particular very economical in particular if a control device is used which also serves other functions and is available to all manners. Data carriers suitable for the computer program include magnetic, optical or electrical memories such as hard disks, flash memories, EEPROM or DVD memories. The program can also be downloaded from a network of computers (internet, intranet or others).

Drawings

The present invention will be described below, in more detail with the aid of exemplary embodiments shown in the accompanying drawings in which:

FIG. 1 is a very schematic representation of an internal combustion engine equipped with a fuel injection installation with several injectors, FIG. 2 shows a simplified flowchart of a preferred embodiment of the method of the invention, and FIG. 3 shows the curves of the speed of rotation and of the quantity injected into an internal combustion engine as well as of the current generated by the electric machine according to a preferred embodiment of the method of the invention.

Description of embodiments

FIG. 1 schematically shows the part of an internal combustion engine equipped with a fuel metering system on which the invention is based, bearing the reference 10. The internal combustion engine is, for example, a diesel engine.

The internal combustion engine 10 has a fuel tank 12 in which a supply system 14 takes the fuel to supply a high pressure fuel line 16. The supply system 14 comprises, for example, a high pressure pump and a dosing unit.

The high pressure fuel line 16 is, for example, in the form of a common rail. The high pressure fuel line 16 is connected to the injectors 18 to inject the fuel directly into the combustion chambers of the cylinders 20 associated with the injectors 18. The operation of the internal combustion engine 10 and in particular of its fuel injection installation comprising the supply system 14, the high pressure fuel line 16 and the injectors 18 is controlled by a calculation unit constituted here by the engine control unit 22. The control device 22 makes it possible to enter the input values, for example the current speed of rotation (engine speed) and to supply output values or to control the actuators, in particular to control the injectors 18.

The crankshaft 24 of the internal combustion engine 10 is connected by a belt transmission 30 to an electric machine 40 operating as an engine or as a generator, for example, in the case of a hybrid engine. The electric machine 40 is also controlled by the control device 22. The electric machine 40 is connected to the battery 42 of the vehicle on-board network by means of a rectifier 41.

The control apparatus 22 is programmed to execute a preferred embodiment of the method of the invention as will be described below with reference to FIGS. 2 and 3. Advantageously, there is thus a method of diagnosing the injectors by the program applied by the control unit or by a workshop tester. FIG. 2 shows the flowchart of a preferred embodiment of the method of the invention and FIG. 3 shows the curves representing the speed of rotation (n) and the dose injected (m) of the internal combustion engine 10 as well as the intensity (i) of the current generated by the electric machine; these different variables are represented as a function of time (t) for the execution of an embodiment of the method of the invention.

In an optional first step 401, it is first checked whether the release conditions are met. These include checking the state of charge of the battery 42 to find out if the battery is not fully charged and that it is able to receive electrical energy generated during the test.

It is only if the release conditions are fulfilled that a step 402 is also optional. In this step, the functions which can influence the result of the test are blocked, in particular the regeneration function of the particle filter or the catalyst.

In step 403, the internal combustion engine is operated in a defined operating state. In particular, provision is thus made to operate at a set speed of rotation (n), for example at idle speed or at a speed of rotation raised with respect to that of idle speed. In addition, to arrive at a defined operating state, it is necessary to predefine the setpoint values of the pressure in the high-pressure accumulator 16 and also the setpoint values of other components of the internal combustion engine 10 and in particular those relating to the valve. exhaust gas re-injection, throttle valve, turbocharger actuators and others. The current injected dose (m) is advantageously blocked.

The actual verification of the injectors 18 begins with step 404 at a first instant to (see FIG. 3). In particular, the load applied by the electric machine 40 is increased step by step or (almost) continuously. This load must be compensated by the internal combustion engine 10 so that its speed of rotation (n) remains constant. The total quantity injected (m) thus increases. Preferably, the relative quantities injected by the different injectors are adapted at the same time so that all the injectors supply the same torque component.

The driving of the electric machine 40 by the internal combustion engine 10 generates an electric current. The electric current obtained is measured and is directly related to the torque generated by this injection. In particular, it is possible to measure the charging current supplying the battery 42.

To obtain a desired setpoint current in the battery, in step 405, the injected dose (m) is adjusted by iterating until the actual current corresponds to the setpoint current, for example at time ti. In this way we can determine the difference between the quantity injected (m) for the charging current 0 and the charging current X or the evolution of the quantity injected for the charging current 0 (to) up to the current of load X (ti). For operation, we can compare in particular to reference values. The reference value describes an increase in the charging current of 10A for an increase in the quantity injected per operating cycle of 10 mg.

If a more or less quantity has to be injected, the overall amount injected is not correct. At the same time the torque balancing described makes it possible to calculate corrections for the quantity or dose injected. By combining the two correction methods, information is obtained concerning the magnitude of the absolute defect, individual of each injector. This makes it possible to diagnose the various injectors to consider them defective if the necessary corrective is too important.

Optionally, in step 406, at time t2, the actuator is checked which influences the energy supplied to the internal combustion engine 10. The actuator setting value is thus modified, for example, the degree d opening of the exhaust gas recycling valve by increasing it for example. This is reflected in the example mentioned by a reduction in the power supplied by the internal combustion engine 10 so that if the injected dose (m) remains the same, it will be necessary to apply a lower electrical charge to maintain the speed of rotation. (n) constant. Then the current (i) decreases.

From the degree of reduction it can be concluded that the actuator is suitable for operation.

The process ends with step 407, for example, at the request of the service technician or if at least one release condition is no longer met thereafter (for example, if the battery is fully charged.

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NOMENCLATURE OF MAIN ELEMENTS

Internal combustion engine

Fuel tank

Fuel system

High pressure pump

Injector

Cylinder

Engine control unit

Belt transmission

Electric machine operating as a motor or as

Generator

Rectifier

On-board network battery

Process steps

Claims (9)

1) Method for determining an injection dose of at least one injector (18) of the fuel metering system of an internal combustion engine (10) of a vehicle according to which the internal combustion engine (10) is coupled to an electric machine (40) for transmitting a torque, the current (1) generated by the electric machine (40) when the vehicle is stopped is determined, the internal combustion engine (10) operating at a certain speed of rotation ( n) predefined and under a predefined load, and the injection dose (m) of an injector (18) is fixed on the basis of the intensity of the current (1) generated by the electric machine (40). 2 °) Method according to claim 1, characterized in that the intensity of the current (1) generated by the electric machine (40) is regulated to a set value by varying the injection dose (m) by at least an injector (18). 3 °) Method according to claim 1 or 2, characterized in that one balances the participation of the injector (18) in the torque before determining the injection dose (m). 4 °) Method according to any one of the preceding claims, characterized in that one determines the evolution of the value of the intensity (1) of the current generated by the electric machine (40) for several different charges and from from this evolution, we conclude that the injector (18) is suitable for operation. 5 °) Method according to any one of the preceding claims, characterized in that one modifies the setting value of an actuator influencing the energy supplied by the internal combustion engine, and one concludes with the aptitude for operation of the actuator from the intensity of the current (1) generated by the electric machine (40). 6 °) Method according to any one of the preceding claims, characterized in that before determining the intensity of the current (1) generated by the electric machine (40), it is checked whether at least one release condition is met and / or at least one function is blocked which can influence the result of the test and / or the thermal machine (10) is put into a determined operating state. 7 °) Method according to any one of the preceding claims, characterized in that the method is applied in a workshop. 8 °) computing unit (22) executing the method according to any one of the preceding claims, for determining an injection dose of an injector (18) of a fuel metering system of an internal combustion engine (10 ) of a vehicle according to which the internal combustion engine (10) is coupled to an electric machine (40) to transmit a torque, the current (1) generated by the electric machine (40) when the vehicle is stopped is determined, the internal combustion engine (10) operates at a certain predetermined speed of rotation (n) and at a predefined load, and the injection dose (m) of an injector (18) is concluded from the value of the current (1) generated by the electric machine (40). 9 °) computer program applied to a computing unit (22) to execute the method according to one of claims 1 to 7, and memory readable by a machine comprising this computer program. 1/2 Ο CM Ο CN Ο CN CN 2/2