Auxiliary device for controlling an engine with electromagnetically controlled injectors

Abstract

The invention relates to an auxiliary engine control device (30) configured to be interposed between an ECU (12) and an electromagnetic injector of a combustion engine. The device comprises a simulation stage (40), configured to bring a first high-side connection terminal (31) to a predefined potential and to apply a voltage curve to a first low-side connection terminal (33). The device comprises a microcontroller (44) connected to the simulation stage, configured, in order to extend fuel injection by the injector, to maintain a current through the coil of the injector when the ECU requests closure of the injector. The microcontroller is also configured to control the simulation stage so that the first high-side connection terminal is brought to the predefined potential and a voltage curve is applied to the first low-side connection terminal, wherein the voltage curve is a simulation of a voltage curve that would appear at the low-side ECU terminal after the ECU requests closure of the electromagnetic injector in the absence of the auxiliary engine control device.

Description

DP.FRTE.0004 / PC 1 SUPPLEMENTARY ENGINE CONTROL DEVICE FOR ELECTROMAGNETIC-CONTROLLED INJECTORS Technical Field

[0001] In general, the invention relates to a supplementary device for controlling an internal combustion engine. Technological background

[0002] The state of the art includes complementary engine control devices that supplement a car's original equipment and enable improved performance in terms of power, engine torque, responsiveness, and / or harmful emissions (CO2, NOx). X (e.g., soot, etc.) This is referred to as automotive "personalization" (or "tuning").

[0003] The function of injectors is to inject precise quantities of fuel into the cylinders of an internal combustion engine. The engine control unit (ECU) controls an electromagnetically operated injector (coil-type or electromagnet injector) by controlling the current flowing through the injector coil. The magnetic field generated by the coil opens the injector by lifting, or allowing the needle (the injector's closing mechanism) to rise. Modulating the current controls the magnetic flow through the coil. When the ECU cuts off the current, the needle is pushed back onto its seat, closing the injection ports.

[0004] Document DE 198 36 113 describes an additional engine control device connected to the electromagnetic fuel injection valves. This allows the injection durations determined by the original engine control unit to be extended, resulting in an increased quantity of fuel injected. A similar device is described in document DE 198 37 060.

[0005] Document EP 2 143 917 describes an additional engine control device that is connected between the original engine control unit and the injection system. This additional device intercepts the signals sent by the original engine control unit to the injection system and replaces them with signals that define modified fuel quantities based on engine speed. DP.FRTE.0004 / PC 2 exceeds a certain threshold. More specifically, beyond a certain engine speed, the amount of fuel determined by the supplementary device is reduced compared to that predicted by the original control unit. The resulting effect of this intervention is that the driver experiences less dynamic behavior from their car at high engine speeds. This naturally encourages them to shift gears and adopt an economical, and therefore environmentally friendly, driving style.

[0006] Document EP 2957752 A1 describes an add-on motor control device comprising a microcontroller, non-volatile memory, an interface unit, an analog input, and an analog output. The interface unit connects the microcontroller to a computer bus and allows the microcontroller to listen for data on the bus. The analog input is connected to the microcontroller via an analog-to-digital converter and is used to connect the add-on device to a sensor. The analog output is connected to the microcontroller via a digital-to-analog converter and is used to connect the add-on device to an analog input of the original motor control unit.The microcontroller is designed so that it can listen to data on the bus, calculate a correction of a signal applied to the analog input based on a map stored in memory, and output a corrected signal to the analog output, which corresponds to the signal applied to the analog input but includes said correction.

[0007] Document FR 3045729 concerns a bioethanol conversion system that allows gasoline vehicles to use both unleaded gasoline (SP95 and SP98) and high-ethanol fuel (e.g., E85). The system includes an additional engine control device that modifies the injector signal (affecting its opening time) by connecting only via a tap into the injector's power supply wires.

[0008] US Patent 2010 / 332104 A1 relates to a device for converting a conventional internal combustion engine designed to run on conventional (non-alcohol) fuel into an engine capable of running on alcohol, gasoline, or any mixture of the two. The device intercepts control signals sent by the engine control unit (ECU) and adjusts the signals for fuels containing alcohol. The device acquires the pulse-width modulated signal from the ECU and modifies this signal. DP.FRTE.0004 / PC 3 adds a pulse width so that the resulting sum is adapted to the modified fuel (containing alcohol). The correction can be constant. The modified signal is then sent by the device to the fuel injectors.

[0009] Some modern ECUs perform advanced diagnostic routines, which may trigger an engine fault if an additional engine control device is inserted between the ECU and the injectors. General description

[0010] A complementary engine control device better suited for modern cars is proposed.

[0011] The supplementary engine control device according to the invention is intended to be interposed between the ECU and the electromagnetic injectors of an internal combustion engine. The device comprises: a high-side (HS) stage including a first HS connection terminal for connecting the supplementary engine control device to an HS ECU terminal and a second HS connection terminal for connecting the supplementary engine control device to an HS pole of an electromagnetic injector coil; a low-side (LS) stage including a first LS connection terminal for connecting the supplementary engine control device to an LS ECU terminal and a second LS connection terminal for connecting the supplementary engine control device to an LS pole of the electromagnetic injector coil; the HS stage comprising a first branch connecting the first HS connection terminal to the second HS connection terminal;the LS stage comprising a second branch, connecting the first LS connection terminal to the second LS connection terminal, with a first electronic switch to close or open the second branch; the HS stage comprising a second electronic switch arranged to apply a supply voltage to the second HS connection terminal and the LS stage comprising a third electronic switch arranged to ground the second LS connection terminal. The supplementary engine control system also includes: DP.FRTE.0004 / PC 4 a simulation stage connected to the first HS connection terminal and the first LS connection terminal, the simulation stage being configured to pull the first HS connection terminal to a predefined potential and to apply a voltage curve to the first LS connection terminal; a microcontroller connected to the first, second and third electronic switches and to the simulation stage, the microcontroller being configured, in order to extend a fuel injection by the electromagnetic injector, o to open the first electronic switch and thus the second branch when the ECU requests the closure of the electromagnetic injector, o to close the second and third switches in order to maintain a current through the coil;and to control the simulation stage so that the first HS connection terminal is pulled to a predefined potential and a voltage curve is applied to the first LS connection terminal, the voltage curve being a simulation of a voltage curve that would appear at the ECU LS terminal after the request to close the electromagnetic injector by the ECU in the absence of the additional engine control device.;

[0012] The first branch connecting the first HS connection terminal to the second HS connection terminal may include a diode oriented from the first HS connection terminal to the second HS connection terminal.

[0013] The supplementary engine control device may include a voltage sensor connected to the first LS connection terminal to detect a voltage increase when the ECU requests the closure of the electromagnetic injector. The microcontroller can be configured to detect the closure of the electromagnetic injector when the voltage at the first LS connection terminal exceeds a threshold. Exceeding the threshold can trigger an interrupt in the microcontroller.

[0014] Preferably, the simulation stage is configured to incorporate a needle closure signature into the voltage curve applied to the first low-side connection terminal. The needle closure signature can consist of a characteristic voltage variation at the moment the injector physically closes. More generally, the microcontroller can be configured to control the stage of DP.FRTE.0004 / PC 5 simulation so as to produce any characteristic signal (signature) whose appearance is monitored by the ECU.

[0015] According to a preferred embodiment of the invention, the simulation stage comprises one or more storage capacitors connected to the first high-side connection terminal through a diode, the simulation stage being configured to generate the voltage curve at the first low-side connection terminal using a discharge of the storage capacitor(s).

[0016] The simulation stage is configured to generate the needle closure signature by modifying the discharge of the storage capacitor(s).

[0017] According to a preferred embodiment of the invention, the simulation stage includes a current source for pulling the first high-side connection terminal to a predefined potential, e.g. to ground.

[0018] Preferably, the complementary motor control device includes non-volatile memory connected to or integrated with the microcontroller, the microcontroller having access to data stored in the memory, e.g., one or more maps. The microcontroller and the memory (and possibly other components) can be integrated on the same chip, so as to form a system-on-a-chip (SoC).

[0019] The complementary control device may include an interface unit configured to connect the microcontroller to a computer bus (e.g., a PT-CAN bus), enabling the microcontroller to listen for data on said bus and, optionally, to transmit data on said bus.

[0020] Preferably, the complementary engine control device includes several channels configured in this way, so as to be able to control several electromagnetic injectors in parallel.

[0021] The additional device can intercept the injector control signals from the ECU and replace them with modified control signals. The corrections or modifications applied by the microcontroller may depend on input data, such as data monitored on a data bus (e.g., engine speed, accelerator pedal position, and / or oil temperature), and a map stored in memory. The modifications may also depend on other parameters. DP.FRTE.0004 / PC 6 obtained on analog lines to which the supplementary device is connected. The supplementary device modifies the injector control, e.g., injection durations, resulting in different engine behavior. This approach allows, in particular, the engine to run on a different type of fuel than the one for which it was initially configured.

[0022] The engine control module according to the invention allows for a more accurate reproduction of the voltage signal expected by the ECU at its LS terminal when it requests injector closure. Consequently, the risk of the ECU detecting a malfunction and entering error mode is significantly reduced. The engine control module is particularly suitable for integration into vehicles whose ECUs monitor for specific signatures in the voltage signal or perform advanced diagnostics on this signal. It should be noted that the proposed solution can be adapted to different types of vehicles and / or fuels through programming and / or configuration of the microcontroller and / or the simulation stage. Brief description of the drawings

[0023] Other features and characteristics of the invention will become apparent from the detailed description presented below, by way of illustration, with reference to the attached drawings which show: Fig. 1: an engine control unit (ECU) connected to the coil of an electromagnetic injector according to the prior art; Fig. 2: a diagram of the voltages at the HS and LS terminals of the ECU as a function of time t during a pilot cycle of a main injection according to the state of the art; Fig. 3: Diagram of a complementary engine control device according to an embodiment of the invention connected between an ECU and the coil of an electromagnetic injector;

[0024] In figures 1 and 3, the dashed lines are used to delimit groups of components or "levels" which are referred to in the text. DP.FRTE.0004 / PC 7 Detailed description

[0025] An electromagnetic injector uses a coil that is activated by currents. The magnetic field generated by the coil when a current passes through it creates a force that lifts a mechanical component of the injector against a force exerted by a spring.

[0026] Figure 1 shows, by way of illustration, how the current through the coil 10 of an electromagnetic injector is controlled by an ECU 12. The coil 10 is arranged between an HS (high side) terminal 14 and an LS (low side) terminal 16 of the ECU 12. The ECU 12 flows a direct current to open and keep open the injector by applying a positive voltage to the HS terminal 14 and grounding the LS terminal 16.

[0027] The injector's response time can be reduced if the initial current intensity is high. However, since the injector coil is an inductor, it opposes changes in the current flowing through it. For example, after applying a voltage U, the coil current, initially 0, increases according to the law where t is the time, I the current intensity, R the coil resistance, L the coil inductance, and T = L / R the time constant. It can be seen that a high initial voltage is necessary for the current in the coil to reach a desired current intensity in a short time. The voltage of a conventional vehicle battery 18 (supplying, e.g., 12 V) is insufficient to power the injector coil 10 in the initial phase. To increase the voltage to a higher level, e.g., 48 V or 60 V, the ECU 12 can connect the coil 10 to a boost converter 20. A higher supply voltage reduces the injector opening delay. Once the injector is open, such a high voltage is no longer needed, the battery voltage will be sufficient: coil 10 can therefore be disconnected from boost converter 20 (using switch E2) and connected to battery 18 (using switch E2).The current can be pulse-width modulated (PWM) by switch E1 to keep the injector open with a minimum current.

[0028] Figure 2 schematically illustrates the voltages applied by an ECU 12 to its HS and LS terminals, respectively. The ECU 12 requests the injector to open by applying a boost voltage (approximately 60 V) to the HS terminal, while the LS terminal is at this stage DP.FRTE.0004 / PC 8 connected to ground. The boost voltage at the HS terminal is maintained for a certain time (boost phase). When the injector is opened, ECU 12 reduces the voltage at the HS terminal and applies the pulse-width modulated battery voltage (e.g., 12 V) (PWM phase).

[0029] To close the injector, the ECU 12 opens switch E3, thus disconnecting terminal LS 16 from ground. Due to the inductance of coil 10, this results in a voltage spike (limited in amplitude by, for example, a freewheeling diode 22). The falling edge of this spike resembles an exponential decay curve (see Figure 2). However, when the magnetic field of coil 10 is no longer sufficient to hold the injector's mechanical element in the open position, the element moves and induces a small, characteristic change in the voltage across the coil. Since the induced voltage is at its maximum just before the mechanical element reaches its seat, it allows the precise determination of the injector needle's closing time. This characteristic voltage change is called the needle closure signature.A modern ECU can be equipped with a voltage sensor 24 between its HS 14 and LS 16 terminals and configured to detect the presence of the needle closing signature within a predefined time interval for diagnostic purposes. If the ECU 12 detects the absence of the needle closing signature within this interval, it can conclude that there is a fault in the injection system and trigger the check engine light and / or activate engine limp mode.

[0030] An advantageous embodiment of the invention relates to a supplementary engine control device that can be interposed between the ECU and the electromagnetic injectors of an internal combustion engine in order to extend the injector opening time and thus increase the amount of fuel injected. The device can, in particular, be used to change engine behavior and / or to adapt the engine to a different type of fuel, e.g., E85 instead of E10.

[0031] Figure 3 schematically shows a complementary engine control device 30 (hereinafter "device" or "device 30") interposed between the ECU 12 and the coil 10 of an electromagnetic injector.

[0032] Device 30 includes a high-side (HS) stage 26 comprising a first HS connection terminal 31 for connecting device 30 to ECU terminal HS 14 and a second HS connection terminal 32 for connecting device 30 to the HS pole of the coil DP.FRTE.0004 / PC 9 10. The device 30 further includes a lower side (LS) stage 28 including a first connection terminal LS 33 for connecting the device 30 to the ECU terminal LS 16 and a second connection terminal LS 34 for connecting the device 30 to the LS pole of the coil 10. When the device 30 is installed, the direct connection between the HS terminal 14 of the ECU 12 and the coil 10 and the direct connection between the LS terminal 16 of the ECU 12 and the coil 10 are interrupted (illustrated by the scissors) and diverted via the HS stage 26, respectively the LS stage 28, of the device 30.

[0033] The HS 26 stage of the device 30 includes a first branch 36 connecting the first HS 31 connection terminal to the second HS 32 connection terminal. The first branch 36 includes a diode 37 oriented from the first HS 31 connection terminal to the second HS 32 connection terminal.

[0034] The LS 28 stage includes a second branch 38, connecting the first connection terminal LS 33 to the second connection terminal LS 34. The second branch 38 includes an electronic switch S1 to close or open the second branch 38.

[0035] Stage HS 26 includes an electronic switch S7 arranged to apply a supply voltage (e.g. battery voltage) to the second connection terminal HS 32.

[0036] The LS 28 stage includes an electronic switch S2 arranged to ground the second connection terminal LS 34.

[0037] The device 30 includes a simulation stage 40 connected to the first HS connection terminal 31 and the first LS connection terminal 33. The simulation stage 40 is configured to pull the first HS connection terminal 31 to a predefined potential, and to apply a voltage curve to the first LS connection terminal 33.

[0038] To pull the first HS 31 connection terminal to ground, the simulation stage 40 includes a current source 42 that can be connected to the first HS 31 connection terminal via an electronic switch S4. When the electronic switch S4 is closed and the current source 42 is active, the diode 23 of the ECU 12 is biased to ground. Consequently, the potential at the first HS 31 connection terminal (and therefore the voltage at the HS 14 terminal of the ECU) is -Useuii, where Useuii is the threshold voltage of diode 23. DP.FRTE.0004 / PC 10

[0039] The device 30 further includes a microcontroller 44, a voltage sensor 46 connected to the first or second HS connection terminal 31, 32, a voltage sensor 48 connected to the second LS connection terminal 34 and a current sensor 50 arranged to measure the current through the coil 10. The microcontroller 44 controls the operation of the device 30. Preferably, it includes a network interface for connecting it to one or more computer buses of the car, e.g. the PT-CAN bus (“Powertrain Controller Area Network”) as well as an internal or external memory 52 in which the map(s) defining the engine reprogramming are stored.

[0040] The device 30 can operate in a passive mode, in which the control of the injector is not modified. In this operating mode, the microcontroller 44 opens (or keeps open) switches S2, S3, S4, S5, S6 and S7 and closes (or keeps closed) switch S1.

[0041] If device 30 is operating in active mode, in which it modifies the injector opening time, the main operation is as follows.

[0042] The initial configuration corresponds to the passive mode configuration (S2, S3, S4, S5, S6, and S7 open, and S1 closed). a. The microcontroller 44 monitors the voltage measured by the voltage sensor 46. When the ECU 12 requests the injector to open, it applies the "boost" voltage to its HS terminal 14 by closing switch E2, with switch E3 closed. The onset of the signal requesting the injector to open is detected by the microcontroller 44 as the rising edge of the voltage measured by the voltage sensor 46. b. During the boost phase, a storage capacitor 54 of the device 30, connected via a diode 53 to the first HS connection terminal 31, is charged to approximately the boost voltage. c. The ECU 12 terminates the boost phase by opening switch E2 and then applies the battery voltage by closing switch E1. The ECU 12 can modulate the voltage at its HS 14 terminal using a PWM control of switch E1. d.When ECU 12 requests injector closure, it opens switch E3, resulting in a rise in voltage at the second terminal of. DP.FRTE.0004 / PC 11 LS connection 34, monitored by voltage sensor 48. When microcontroller 44 detects this rising edge, it rapidly opens (e.g., reaction time < 10 ps) switch S1 and closes switch S2 to reconnect the second LS connection terminal 34 to ground, thus keeping the injector open. e. While switch S1 is open, device 30 monitors the voltage between terminals HS 14 and LS 16 of ECU 12, as well as the current through injector coil 10. o Monitoring the voltage between terminals HS 14 and LS 16 of ECU 12: After opening switch E3, ECU 12 expects a rapid increase in voltage at its LS 16 terminal, limited by diode 22 to the boost voltage for a duration Ddamp (see Figure 2), followed by a voltage decrease, primarily exponential. ECU 12 also expects this falling edge to contain the injector closing signature. To produce a voltage signal at the first LS 33 connection terminal mimicking the expected signal, microcontroller 44 first closes switch S3, which brings the voltage at input 56 of the voltage follower 58 to approximately the boost voltage. At the same time, the closing of switch S3 causes the capacitance 60 to be charged through resistor 62. After a certain time, preferably at least approximately equal to Ddamp, e.g. 100 ps, ​​the microcontroller 44 opens switch S3 and closes switches S4, S5 and S6.Closing switch S4 pulls the first HS 31 connection terminal to the defined potential (-Useuii). Closing switches S5 and S6 discharges capacitor 60. The injector's closing signature is simulated by a brief opening (e.g., 20 ps) of switches S5 and S6: their opening interrupts the discharge of capacitor 60 and causes a small voltage rise at input 56 of the voltage follower 58. The microcontroller 44 then closes switches S5 and S6 so that the discharge of capacitor 60 can continue. Capacitors and resistors 62, 63, and 64 are sized so that the discharge produces approximately the falling edge expected by ECU 12. They can be adapted to the type of ECU. Switches S5 and S6 can be controlled in different modes. DP.FRTE.0004 / PC 12 Varying the time constant of the voltage signal: if both switches S5 and S6 are closed, a rapid decrease in voltage is observed at input 56 of the voltage follower 58 (rapid discharge of capacitor 60); if only one of switches S5 and S6 is closed, the voltage decrease is slower (the time constant depends on resistors 62, 63, 64). At the end of this simulation step, the microcontroller 44 opens switches S4, S5, and S6. o Control of the current through the injector coil 10 The microcontroller 44 drives the current through the injector coil 10 by means of a PWM signal sent to switch S7, with switch S2 closed. Preferably, the microcontroller 44 determines the shape (in particular the duty cycle) of the PWM signal from current and / or voltage measurements taken during the last previous injection(s). Alternatively, the microcontroller 44 can be configured to control the PWM signal in closed loop based on current measurements provided by the current sensor 50. The microcontroller 44 requests the injector to close (depending on the modified injection duration) by opening switch S2. The PWM signal sent to switch S7 is stopped (by opening switch S7) at the latest when switch S2 is opened or, preferably, a certain time (e.g., about 100 ps) before switch S2 is opened. f. When step e. is finished, i.e.when switches S2, S4, S5, S6, S7 have been opened, the microcontroller 44 closes switch S1 and returns device 30 to the starting configuration.

[0043] The microcontroller 44 measures the time between the opening request signal and the closing request signal emitted by the ECU 12, which allows it to calculate the injection time T, as predicted by the ECU 12. Preferably, the microcontroller 44 is configured to calculate, based on Ti, the correction (extension) of the injection time (which may depend on other parameters, such as, e.g., alternative fuel, engine speed, accelerator pedal position, a driving mode selected by the driver, etc.) and determine the delay or interval within which the ECU 12 expects the needle closing signal. The microcontroller 44 can thus produce a simulation of the needle closing signal at time DP.FRTE.0004 / PC 13 corresponds to this. The microcontroller 44 also measures the current through coil 10. These current measurements allow the calculation of the rise and fall slopes of the current through the coil, and from this, the duty cycle of the PWM signal to be applied. The microcontroller can be configured to open switch S7 and / or reduce the duty cycle of the PWM modulation if the current through coil 10 is too high.

[0044] The supplementary device 30 can therefore be interposed between the ECU 12 and the electromagnetic injectors, intercept the control signals emanating from the ECU, and substitute modified (corrected) control signals. The corrections or modifications applied by the device 30 may depend on input data, e.g., data monitored on a data bus (e.g., data relating to engine speed, accelerator pedal position, and / or oil temperature, etc.), and on a map stored in memory 52. ​​The corrections or modifications may also depend on other parameters obtained on analog lines to which the device 30 is optionally connected. The device 30 can thus modify the control of the electromagnetic injectors, e.g., the injection durations, resulting in different engine behavior.

[0045] The engine control device 30 reproduces the voltage curve expected by the ECU at its LS terminal. This significantly reduces the risk of the ECU detecting a malfunction and entering error mode. It should be noted that device 30 can operate in a passive mode, in which it simply allows the control signals emitted by the ECU 10 to pass through. This operating mode can be used to analyze and / or record the evolution of currents and voltages during one or more injection cycles. This analysis or recording can then be used by the microcontroller 44 to control the simulation stage 40.

[0046] The switches of device 30 preferably include insulated gate field-effect transistors, e.g. metal-oxide-semiconductor field-effect transistors, better known by the English acronym "MOSFET".

[0047] While specific embodiments have just been described in detail, those skilled in the art will appreciate that various modifications and alternatives to these can be developed in light of the overall teaching provided by the DP.FRTE.0004 / PC 14 presents a disclosure of the invention. Therefore, the specific arrangements and / or methods described therein are intended to be given solely by way of illustration, without any intention of limiting the scope of the invention, which is determined by the extent of the related claims.

Claims

DP.FRTE.0004 / PC 15 Demands 1. Supplementary engine control device (30) intended to be interposed between an engine control unit, ECU, 12 and electromagnetic injectors of an internal combustion engine, the supplementary engine control device comprising: a top-side stage (26) including a first top-side connection terminal (31) for connecting the supplementary engine control device (30) to a top-side ECU terminal (14) and a second top-side connection terminal (32) for connecting the supplementary engine control device (30) to a top-side pole of a coil (10) of an electromagnetic injector; a bottom-side stage (28) including a first bottom-side connection terminal (33) for connecting the supplementary engine control device (30) to a bottom-side ECU terminal (16) and a second bottom-side connection terminal (34) for connecting the supplementary engine control device (30) to a bottom-side pole of the coil (10) of the electromagnetic injector;the upper side stage (26) comprising a first branch (36) connecting the first upper side connection terminal (31) to the second upper side connection terminal (32); the lower side stage (28) comprising a second branch (38), connecting the first lower side connection terminal (33) to the second lower side connection terminal (34), with a first electronic switch (S1) for closing or opening the second branch (38); the upper side stage (26) comprising a second electronic switch (S7) arranged to apply a supply voltage to the second upper side connection terminal (32) and the lower side stage (28) comprising a third electronic switch (S2) arranged to ground the second lower side connection terminal (34);the complementary motor control device (30) further comprising: a simulation stage (40) connected to the first high-side connection terminal (31) and to the first low-side connection terminal (33), the simulation stage (40) being configured to pull the first high-side connection terminal to a predefined potential and to apply a voltage curve to the first low-side connection terminal; DP.FRTE.0004 / PC 16 a microcontroller (44) connected to the first, second and third electronic switches (S1, S7, S2) and to the simulation stage (40), the microcontroller (44) being configured, in order to prolong a fuel injection by the electromagnetic injector, o to open the first electronic switch (S1) and therefore the second branch (38) when the ECU (12) requests the closure of the electromagnetic injector, o to close the second and third switches (S7, S2) in order to maintain a current through the coil (10);and to control the simulation stage (40) so that the first high-side connection terminal (31) is pulled to a predefined potential and a voltage curve is applied to the first low-side connection terminal (33), the voltage curve being a simulation of a voltage curve that would appear at the low-side ECU terminal (16) after the request to close the electromagnetic injector by the ECU in the absence of the complementary engine control device (30).

2. The complementary engine control device (30) as claimed in claim 1, comprising a voltage sensor (48) connected to the first bottom-side connection terminal (34) to detect a voltage increase when the ECU (12) requests closure of the electromagnetic injector.

3. The complementary motor control device (30) as claimed in claim 1 or 2, wherein the simulation stage (40) is configured to integrate into the voltage curve applied to the first bottom-side connection terminal a needle closure signature.

4. The complementary motor control device (30) as claimed in any one of claims 1 to 3, wherein the simulation stage (40) comprises one or more storage capacitors (54, 60) connected to the first high-side connection terminal (31) through a diode (53), the simulation stage (40) being configured to generate the voltage curve at the first low-side connection terminal by means of a discharge of the storage capacitor(s) (54, 60).

5. The complementary motor control device (30) as claimed in claim 4, wherein the simulation stage (40) is configured to generate DP.FRTE.0004 / PC 17 the needle closure signature by a modification of the discharge of the storage capacitor(s).

6. The complementary motor control device (30) as claimed in any one of claims 1 to 5, wherein the simulation stage (40) includes a current source (42) for pulling the first high-side connection terminal (31) to a predefined potential.

7. The complementary motor control device (30) according to any one of claims 1 to 6, comprising a non-volatile memory (52) connected to or integrated into the microcontroller (44), the microcontroller (44) having access to data stored in the memory (52).

8. The complementary motor control device (30) according to any one of claims 1 to 7, comprising an interface unit configured to connect the microcontroller (44) to a computer bus (PT-CAN), enabling the microcontroller (44) to listen for data present on said bus and, optionally, to transmit data on said bus.

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