Device and method for controlling a module for heating a plurality of injectors

Abstract

A method, and associated device, for controlling a module for heating a plurality of fuel injectors of an engine of a vehicle, the heating module including a plurality of electromagnetic induction elements each connected to an injector of the plurality of fuel injectors and being configured, when an electric excitation current passes through the electromagnetic induction elements, to heat the injector by induction, the method including a step of generating an electric supply current and a step of generating, from the electric supply current, a plurality of electric excitation currents phase shifted relative to one another and materialized by electric excitation current signals, each of the electric excitation currents intended to supply one of the electromagnetic induction elements. The method being notable in that the electric excitation current signals are phase shifted such that the sum of the absolute values of the amplitudes of the signals is constant.

Claims

1. A device for controlling a module configured to heat a plurality of fuel injectors of an engine of a vehicle, said heating module including a plurality of electromagnetic induction devices, each of said electromagnetic induction devices being connected to an injector of the plurality of fuel injectors and being configured, when an electric excitation current passes through said electromagnetic induction devices, to heat said injector by induction, said device comprising: a power generator configured to generate an electric supply current; and a phase shift system configured to generate, from the electric supply current generated by the power generator, a plurality of electric excitation currents phase shifted relative to one another and materialized by electric excitation current signals, each of said electric excitation currents supplying at least one of the electromagnetic induction devices of the plurality of electromagnetic induction devices, the phase shift system comprising a number of H bridges equal to the number of injectors equipped with electromagnetic induction devices, and a controller configured to control the delivery of n electric excitation current signals phase shifted $\frac{{180}^{}}{n}$ via said H bridges, each H bridge enabling delivery of an electric excitation alternating current signal to an electromagnetic induction device at a moment determined by said controller, wherein the phase shift system is configured to phase shift the electric excitation current signals such that, for each of a plurality of duty cycles, the sum of the absolute values of the amplitudes of said signals is equal to a constant value at any given time, wherein an electric excitation current delivered by an H bridge is an alternating current of which the half-period is defined by one of the duty cycles, said duty cycle being selected from one of the values $p\frac{100\%}{n}$ where p is natural number between 0 and n.

2. The device as claimed in claim 1, wherein the electromagnetic induction devices are a plurality of induction coils.

3. A vehicle comprising: an engine comprising a plurality of fuel injectors; a heating module comprising a plurality of electromagnetic induction devices, each of said electromagnetic induction devices being connected to an injector of the plurality of fuel injectors and being configured, when an electric excitation current passes through said electromagnetic induction devices, to heat said injector by induction; and the device for controlling said heating module as claimed in claim 1.

4. A method for controlling the module configured to heat the plurality of fuel injectors of the engine of the vehicle using the device according to claim 1, said heating module including a plurality of electromagnetic induction devices, each of said electromagnetic induction devices being connected to an injector of the plurality of fuel injectors and being configured, when an electric excitation current passes through said electromagnetic induction devices, to heat said injector by induction, said method comprising: generating an electric supply current; generating, from the generated electric supply current, a plurality of electric excitation currents phase shifted relative to one another and materialized by electric excitation current signals, each of said electric excitation currents supplying at least one of the electromagnetic induction devices of the plurality of electromagnetic induction devices, n electric excitation current signals being generated by being phase shifted by $\frac{{180}^{}}{n},$ n being natural number greater than or equal to 1 and equal to the number of injectors equipped with electromagnetic induction devices, each electric excitation current signal being an alternating current of which the half-period is defined by a duty cycle selected from one of the values $p\frac{100\%}{n}$ where p is a power level of the duty cycle and is a natural number between 0 and n, such that, for the selected duty cycle, the sum of the absolute values of the amplitudes of said signals is equal to a constant value at any given time.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Further features and advantages of the invention will become clear from the following description provided with reference to the accompanying figures, which are given by way of non-limiting example and in which identical references are given to similar components:

(2) FIG. 1 is a schematic representation of a vehicle according to the invention.

(3) FIG. 2 illustrates electric excitation current signals phase shifted by 45 and of which the duty cycle is 25% for an exemplary application with 4 H bridges.

(4) FIG. 3 illustrates electric excitation current signals phase shifted by 45 and of which the duty cycle is 50% for an exemplary application with 4 H bridges.

(5) FIG. 4 illustrates electric excitation current signals phase shifted by 45 and of which the duty cycle is 75% for an exemplary application with 4 H bridges.

(6) FIG. 5 illustrates electric excitation current signals phase shifted by 45 and of which the duty cycle is 100% for an exemplary application with 4 H bridges.

DETAILED DESCRIPTION OF THE INVENTION

(7) FIG. 1 schematically illustrates a vehicle 1 according to the invention. The vehicle 1 is preferably a motor vehicle, although this does not limit the scope of the present invention, which can apply to any type of vehicle comprising fuel injectors.

(8) Such a vehicle 1 comprises an engine 3, a heating module 8 and a device 10 for controlling said heating module 8.

(9) In this example, the engine 3 is an internal combustion engine, although this does not limit the scope of the present invention. Such an engine 3 comprises n cylinders 4 and n fuel injectors 5, n being a natural number greater than or equal to 1. Each cylinder 4 is connected to a piston 6 and comprises a combustion chamber 4a into which an injector 5 introduces fuel of which the combustion combined with a combustion agent allows the actuation of the corresponding piston 6. The mechanical force created by the movement of the piston 6 is then transmitted, via transmission elements 7, to the wheels (not shown) of the vehicle 1 in order to set said vehicle in motion.

(10) The heating module 8 comprises n electromagnetic induction means, each of said electromagnetic induction means being connected to an injector 5 of the plurality of fuel injectors 5 and being configured to heat said injector 5 by induction when an electrical excitation current passes through said electromagnetic induction means.

(11) In this preferred example, each electromagnetic induction means is present in the form of an electromagnetic induction coil 9 wound around an injector 5 so as to allow the heating of the fuel passing through the injector 5 when the coil 9 is supplied with an electrical excitation current.

(12) The device 10 for controlling the heating module 8 of the fuel injectors 5 comprises a generation unit 12 and a phase shift unit 14.

(13) The generation unit 12 is configured to generate an electric supply current for the phase shift unit 14 and may be present in the form of a power supply battery associated with a current hashing device. Such an assembly for example delivers an alternating current of sufficiently high amplitude and frequency to induce rapid heating of the coils, for example 25 amps at 10 kHz.

(14) The phase shift unit 14 is configured to deliver, from the electric supply current generated by the generation unit 12, a plurality of electric excitation currents materialized by electric excitation current signals, and each of said electric excitation current signals supplies one of the electromagnetic induction coils 9.

(15) In accordance with the invention, the phase shift unit 14 is configured to phase shift the electric excitation current signals such that the sum of the absolute values of the amplitudes of said signals is constant in order to eliminate the undulations of the electric supply current at the terminals of the generation unit 12.

(16) To this end, the phase shift unit 14 comprises n H bridges 16 equal to the number of injectors 4 and a means 18 for controlling said H bridges 16, each H bridge 16 making it possible to deliver an electric excitation current signal to an injector 4 at a moment determined by said control means 18.

(17) The control means 18 is configured to determine n separate moments for the provision of n phase-shifted electric excitation current signals by the n H bridges 16.

(18) The phase shift unit 14 is configured to phase shift the electric excitation current signals delivered by the n H bridges 16 phase shifted by

(19) $\frac{{180}^{}}{n}$
relative to one another.

(20) The electric excitation current delivered by an H bridge 16 is an alternating current of which the half-period is defined by a duty cycle. In order to ensure that the sum of the absolute values of the amplitudes of the electric excitation current signals is constant, this duty cycle is selected from one of the values

(21) $p\frac{100\%}{n}$
where p is between 0 and n, n being the number of electromagnetic induction coils 9.

(22) FIGS. 2 to 5 illustrate examples of electric excitation current signals and electric supply current signals for a number of electromagnetic induction coils n equal to 4.

(23) The generation unit 12 firstly generates an electric supply current in a step E1.

(24) Then, in a step E2, the phase shift unit 14 generates, from the electric supply current generated by the generation unit 12, a plurality of electric excitation currents materialized by electric excitation current signals that have been phase shifted such that the sum of the absolute values of the amplitudes of said signals is constant.

(25) With reference to FIG. 1, each H bridge 16 delivers, from the electric supply current generated by the generation unit 12, an electric excitation current, and the means 18 for controlling the phase shift unit 14 periodically determines four separate moments such that the four H bridges 16 periodically deliver four electric excitation current signals phase shifted by 45 relative to one another.

(26) With reference to FIGS. 2 to 5, the electric excitation current signals H1, H2, H3 and H4 are alternating current of which the half-period is defined by a duty cycle and of which the frequency F is fixed and is between 10 kHz and 30 kHz.

(27) In accordance with the invention, the duty cycle of each electric excitation current signal H1, H2, H3 and H4 is selected from one of the values p100%/4 where p is between 0 and 4 (since in the case illustrated in FIGS. 2 to 5 n=4), that is to say the duty cycle assumes the values 0%, 25%, 50%, 75% and 100% respectively.

(28) Such a selection advantageously makes it possible to ensure that the sum of the absolute values of the amplitudes of the electric excitation current signals H1, H2, H3 and H4, corresponding to the signal of the electric supply current I generated by the generation unit 12, is constant and that there are thus no longer any undulations of the electric current at the terminals of the generation unit 12.

(29) The choice of the duty cycle is made depending on the necessary heating power. Thus, the higher the duty cycle, the greater the heating power.

(30) Still with reference to FIGS. 2 to 5, each electric excitation current supplies one of the electromagnetic induction coils 9, denoted H1, H2, H3 and H4 consecutively, of the heating module 8 in order to heat the fuel passing through the injector 5 on which the coil 9 is wound.

(31) FIGS. 2 to 5 illustrated the variations of the electric excitation current signals H1, H2, H3 and H4 between 3 A and 3 A over a period defined by the frequency F.

(32) With reference to FIG. 2, the duty cycle of each electric excitation current signal H1, H2, H3 and H4 is 25%. The electric excitation current signals H1, H2, H3 and H4 are phase shifted by 45, the current range of said signals varies between 3 A and 3 A, but two signals are never at the maximum amplitude thereof (in absolute value) of 3 A simultaneously. Since the signal of the electric supply current I corresponds to the sum of the absolute values of the amplitudes of the electric excitation current signals H1, H2, H3 and H4, it is thus constant and equal to 3 A.

(33) With reference to FIG. 3, the duty cycle of each electric excitation current signal H1, H2, H3 and H4 is 50%. The electric excitation current signals H1, H2, H3 and H4 are phase shifted by 45, the current range of said signals varies between 3 A and 3 A, and two of the signals are at the maximum amplitude thereof (in absolute value) of 3 A simultaneously, whilst the amplitude of the two other signals is zero. Since the signal of the electric supply current I corresponds to the sum of the absolute values of the amplitudes of the electric excitation current signals H1, H2, H3 and H4, it is thus constant and equal to 6 A.

(34) With reference to FIG. 4, the duty cycle of each electric excitation current signal H1, H2, H3 and H4 is 75%. The electric excitation current signals H1, H2, H3 and H4 are phase shifted by 45, the current range thereof varies between 3 A and 3 A, and three of the four signals are at the maximum amplitude thereof (in absolute value) of 3 A simultaneously, whereas the amplitude of the fourth signal is zero. The signal of the electric supply current I, corresponding to the sum of the absolute values of the amplitudes of the electric excitation current signals H1, H2, H3 and H4, is thus constant and equal to 9 A.

(35) With reference to FIG. 5, the duty cycle of each electric excitation current signal H1, H2, H3 and H4 is 100%. The electric excitation current signals H1, H2, H3 and H4 are phase shifted by 45, the current range thereof varies between 3 A and 3 A, and the four signals are at the maximum amplitude thereof (in absolute value) of 3 A simultaneously. The signal of the electric supply current I, corresponding to the sum of the absolute values of the amplitudes of the electric excitation current signals H1, H2, H3 and H4, is thus constant and equal to 12 A.

(36) The method according to the invention thus advantageously makes it possible to avoid the use of an EMC filter, which reduces the dimensions of the device whilst avoiding the generation of electromagnetic interference created by undulations in current at the terminals of the generation unit of the device, simultaneously reducing cost.

(37) The invention is not limited to the embodiment described above and can be extended to any adaptation envisaged by a person skilled in the art. For example, it is not necessary to equip all the injectors with heating means, or it is possible to provide more than one injector per cylinder.

(38) Lastly, it will be noted that the invention has been presented for an application of heating fuel injectors of a vehicle engine. Nevertheless, it goes without saying that the invention is applicable to any electromagnetic induction heating device, in particular in all fields of transport or industry.