Method for controlling the power supply of solenoid fuel injectors in a hybrid motor vehicle

Abstract

A method for controlling the electrical power supply of injectors for a hybrid automotive vehicle, including an internal combustion engine and an electric motor. A first electrical network, having a first DC voltage, supplies power to a motor control of the engine. A second electrical network having a second DC voltage, higher than the first DC voltage, supplies power to the electric motor. The method includes connecting the second DC voltage to the injectors; reading the value of the second DC voltage; adapting control parameters of the injectors based on the value of engine speed, engine temperature and injection pressure upstream of the injectors; and controlling the injectors using the second DC voltage. Wherein there is no change in the control parameters when the value is higher than a threshold value; and changing at least one of the control parameters when the value is lower than the threshold value.

Claims

1. A method for controlling the electrical power supply of solenoid fuel injectors for a hybrid automotive vehicle, including both an internal combustion propulsion engine and an electric motor, said internal combustion propulsion engine performing multiple fuel injections per cylinder within an operating cycle, said hybrid automotive vehicle being provided with a first electrical network powered at a first DC voltage that is intended to supply power to a motor control of the internal combustion propulsion engine and a second electrical network powered at a second DC voltage, said second DC voltage being higher than the first DC voltage and intended to supply power to the electric motor, said method comprising: i. connecting the second DC voltage to the electrical power supply of the solenoid fuel injectors; ii. reading the value of the second DC voltage; iii. adapting the control parameters of the solenoid fuel injectors on the basis of the value read in step ii, of an engine speed of the internal combustion propulsion engine, of a temperature of the internal combustion propulsion engine and of an injection pressure upstream of the solenoid fuel injectors; iv. controlling the solenoid fuel injectors using the second DC voltage, wherein: iv.a. there is no change in the injector control parameters when the value is higher than or equal to a threshold value; and iv.b. at least one of the injector control parameters is changed when the value is lower than the threshold value, the at least one of the injector control parameters of the solenoid injectors including fuel injection time; v. performing a consistency test of the adapted control parameters, the consistency test including determining if a total fuel injection time of the adapted control parameters is longer than a time available for the operating cycle of the internal combustion propulsion engine; and vi. lowering a number of the multiple fuel injections when the consistency test of the adapted control parameters fails.

2. A non-transitory computer readable recording medium, on which a computer program is recorded comprising program code instructions for executing the steps of the method as claimed in claim 1.

3. An electronic computer for a hybrid automotive vehicle including both an internal combustion propulsion engine and an electric motor, comprising means for implementing a method for controlling the electrical power supply of solenoid fuel injectors as claimed in claim 1.

4. A non-transitory computer readable recording medium, on which a computer program is recorded comprising program code instructions for executing the steps of the method as claimed in claim 2.

5. An electronic computer for a hybrid automotive vehicle including both an internal combustion propulsion engine and an electric motor, comprising means for implementing a method for controlling the electrical power supply of solenoid fuel injectors as claimed in claim 2.

6. An electronic computer for a hybrid automotive vehicle including both an internal combustion propulsion engine and an electric motor, comprising means for implementing a method for controlling the electrical power supply of solenoid fuel injectors as claimed in claim 2.

7. The method as claimed in claim 1, wherein the at least one of the injector control parameters of the solenoid injectors includes engine angle at the start of fuel injection.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Aspects of the invention will be better understood upon reading the following description. This description is purely illustrative and should be read with reference to the appended drawings, in which FIG. 1 shows a flow diagram presenting the various steps of a method according to an aspect of the invention.

(2) It should be noted that if the FIGURE provides a detailed disclosure of the invention for its implementation, said FIGURE may of course serve to define an aspect of the invention better, as the case may be.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

(3) In the description, the same numerical references denote identical or functionally similar elements.

(4) The method according to an aspect of the invention implements multiple hardware or software components and multiple agents, to which reference will be made throughout the remainder of the description.

(5) In the description, actions are assigned to devices or to programs; this means that these actions are executed by a microprocessor of this device or of the device including the program, said microprocessor then being controlled by instruction codes recorded in a memory of the device. These instruction codes allow the means of the device to be implemented, and therefore allow the undertaken action to be carried out.

(6) FIG. 1 shows a flow diagram implemented by a method for controlling the electrical power supply of solenoid fuel injectors for a hybrid automotive vehicle, including both an internal combustion propulsion engine MCI and an electric motor ME, said hybrid automotive vehicle being provided with a first electrical network powered at a first DC voltage V1 that is intended in particular to supply power to the motor control of the internal combustion propulsion engine MCI and a second electrical network powered at a second DC voltage V2, said second DC voltage V2 being higher than the first DC voltage V1 and intended in particular to supply power to the electric motor ME.

(7) By way of illustrative example, which is in no way limiting with regard to the scope of an aspect of the invention, the value of the first DC voltage V1 is 12 V and it arises from a battery of lead-acid accumulators and the value of the second DC voltage V2 is 48 V and it arises from a battery of lithium-ion accumulators.

(8) The parameters that an aspect of the invention proposes adapting are the fuel injection time Ti and the angle at the start of injection Ai (step I).

(9) Specifically, if the voltage varies, because an aspect of the invention proposes working with the DC voltage delivered by the battery of accumulators powering the electric motor ME, then it is necessary to take into account the fact that the charging time for the inductance of a solenoid fuel injector will vary with the DC voltage that is actually applied. For an assembly of the prior art powering the solenoid injectors at a known and stabilized voltage, this accounting and adaption is not essential.

(10) An aspect of the invention therefore proposes starting with the nominal settings stored in the memory of the engine control computer, for example, and adapting them according to the voltage measured in real time. This value of the second DC voltage V2 measured in real time is referred to as the second available DC voltage V2m.

(11) In step II, the second available DC voltage V2m, along with the engine temperature Tm, the pressure Pm upstream of the solenoid injectors and the engine speed N, are therefore measured.

(12) The engine temperature Tm may be deduced from the temperature of the coolant of the internal combustion propulsion engine MCI, which is typically a parameter tracked by the engine control computers and therefore does not require an additional sensor. This parameter affects the quality of combustion in the cylinders and may lead to the retained injection parameters being corrected.

(13) It is also important to track the pressure Pm upstream of the solenoid injectors, since the rate of the solenoid injectors, and hence the volume injected for a given solenoid injector opening time, may fluctuate. In modern direct injection engines, this pressure Pm is tracked and there is therefore no need to add a sensor to those already present here either.

(14) The engine speed N is also important since it affects the time available for carrying out injections. It is one of the basic quantities tracked in an engine control computer.

(15) It is therefore possible, by using quantities that are available and tracked by the engine control computer, to have an accurate insight into the operating conditions of the internal combustion propulsion engine MCI a short time before the solenoid injector is activated.

(16) In step III, the second available DC voltage V2m is evaluated by comparing it with a threshold. In the illustrated example in which the nominal control voltage of the solenoid injectors is 65 V, the threshold value is 60 V.

(17) If the second available DC voltage V2m is higher than or equal to this threshold of 60 V, then there is no need to correct the injection parameters. The compensation time Ts is set to 0 in step IVb, such that the corrected injection time Tic defined in step V by: Tic=Ti+Ts is identical to the initial injection time Ti.

(18) If the second available DC voltage V2m is lower than this threshold of 60 V, then the injection parameters need to be corrected. The compensation time Ts is calculated by taking into account the previously measured influencing factors, i.e. the engine temperature Tm, the pressure Pm upstream of the solenoid injectors and the engine speed N (step IVa). This corrective factor, the compensation time Ts, is denoted by Ts=f(V2m; Tm; Pm). The corrected injection time Tic defined in step V by: Tic=Ti+Ts is then established.

(19) Step VI makes it possible to compute the corrected angle at the start of injection Aic, defined on the basis of the angle at the start of injection Ai established in step I, decreased by a corrective factor which depends on the compensation time Ts and on the engine speed N, denoted by g (N; Ts).

(20) These corrective factors may be established on the basis of computing laws or else nomograms drawn up for each type of engine during trials.

(21) The two corrected parameters, i.e. the corrected injection time Tic and the corrected angle at the start of injection Aic, are then used by the engine control computer of the internal combustion propulsion engine MCI to monitor the electrical power supply of the solenoid injectors, which are directly powered by the second DC voltage V2.

(22) In one advantageous variant, in the case of an internal combustion propulsion engine MCI including strategies of multiple fuel injections per cylinder within one and the same operating cycle, the introduction of a consistency test is proposed to determine whether or not the envisaged number of multiple injections is possible.

(23) If the consistency test of the adapted control parameters is passed, i.e. if the established total injection time is compatible with the time provided by the operating conditions of the internal combustion propulsion engine MCI, then the number of envisaged multiple injections is kept.

(24) If the consistency test of the adapted control parameters is failed, i.e. if the established total injection time is longer than the time provided by the operating conditions of the internal combustion propulsion engine MCI, then the number of envisaged multiple injections is decreased, even if that means limiting it to a single injection in the least favorable situation.

(25) An aspect of the present invention also covers a recording medium that can be read by a computer, on which a computer program is recorded comprising program code instructions for executing the steps of the method as described above.

(26) Lastly, an aspect of the invention relates to an electronic computer for a hybrid automotive vehicle including both an internal combustion propulsion engine MCI and an electric motor ME, which is noteworthy in that it includes means for implementing a method for controlling the electrical power supply of solenoid fuel injectors according to the features mentioned above.

(27) It should be noted that an aspect of the invention may easily be adapted to actuators within the automotive vehicle other than just the solenoid injectors described above, without departing from the scope of the present invention.

(28) It should also be noted that an aspect of the invention is not applicable such as described to a scenario in which the second DC voltage is substantially higher than the maximum permissible voltage for the solenoid injectors (such as the case of electric motors powered at a voltage of 400 V for example). In such a scenario it would be necessary to provide a voltage buck device if the second DC voltage V2 risked damaging the solenoid injectors.