Fuel conversion system and unit for a heat-engine vehicle, and method for adjusting the distribution of fuel

Abstract

The invention relates to a fuel conversion system and unit for a heat-engine vehicle, and to a method for adjusting the distribution of fuel. The invention relates mainly to a fuel conversion unit (1) for a heat-engine vehicle, the vehicle comprising at least a first injector (4) and at least a second injector (6) that can be operated by a microcontroller (7) of the conversion unit (1), which microcontroller (7) is also designed to collect an injection signal, which conversion unit (1) further comprises a fuel sensor (8), characterized in that the microcontroller (7) is configured to determine the composition of the fuel, and, for each engine cycle: • To determine an injection duration of the first injector (4) from the data in the injection signal; • To determine an injection duration of the second injector (6) from the injection duration of the first injector (4) and from the determined fuel composition, and To operate the second injector (6) for the determined injection duration in order to deliver a complementary quantity of fuel.

Description

DESCRIPTION Title: Fuel conversion unit and system for an internal combustion engine vehicle, and method for adjusting fuel distribution. TECHNICAL FIELD

[0001] The invention falls within the field of fuel conversion systems for internal combustion engine vehicles, in particular bioethanol conversion systems. PRIOR ART AND DISADVANTAGES OF PRIOR ART

[0002] In a context of limiting the use of fossil fuels, fuels containing a significant proportion of biomass have been offered for several years. This is the case, for example, with bioethanol, known as E85 superethanol, which comprises unleaded gasoline and between 65% and 85% by volume of ethanol derived from biomass. However, while the most recent vehicles are compatible with this type of fuel, this is not the case for a large portion of the vehicle fleet currently on the road. Indeed, superethanol has a lower energy density compared to unleaded gasoline such as E10 – which contains up to 10% ethanol – and E5, which contains up to 5% ethanol. The energy released by the combustion of superethanol is therefore insufficient to power the engines of incompatible vehicles. The E5, E10, and E85 labels comply with Directive 2014 / 94 / EU of the European Parliament and of the Council.

[0003] To overcome this drawback, bioethanol conversion kits are available for installation in gasoline vehicles. These kits include a fuel sensor that generates a signal to determine the fuel composition and a microcontroller that controls the vehicle's fuel injectors, ensuring they deliver a sufficient quantity of superethanol to properly fuel the engine. One such kit is described, for example, in publication FR3045729.

[0004] However, vehicle injection strategies, implemented by the vehicle's computer, vary greatly depending on the model. Furthermore, these injection strategies are designed to optimize fuel consumption for a specific type of fuel, generally E5 or E10 gasoline. Therefore, modifying injection strategies to adapt them to another fuel such as E85 superethanol can prove particularly complex. In addition, the Reprogramming of injection strategies by the manufacturer can render inoperative a conversion box already installed on a vehicle. OBJECTIVE OF THE INVENTION

[0005] The invention therefore aims to provide a reliable fuel conversion system that is simple to implement and overcomes the disadvantages of the prior art. DESCRIPTION OF THE INVENTION

[0006] To this end, the invention relates to a fuel conversion unit for an internal combustion engine vehicle, which vehicle comprises at least one fuel tank, an electronic control unit (ECU), at least one first fuel injector fluidly connected to a fuel outlet line from the tank and controllable by the ECU, and at least one second injector fluidly connected to the tank outlet line and controllable by a microcontroller of the conversion unit, which microcontroller is further provided to receive an injection signal emitted by the ECU to the first injector, which conversion unit further comprises a fuel sensor controlled by the microcontroller, characterized in that the microcontroller of the conversion unit is configured to determine the composition of the fuel in the tank from the data of the fuel sensor, and for each engine cycle: • Determine the injection duration of the first injector from the injection signal data; • Determine the injection duration of the second injector based on the injection duration of the first injector and the determined fuel composition, and • Control the second injector according to the determined injection duration to deliver an additional quantity of fuel.

[0007] The casing may also include the following optional features, considered individually or in all possible technical combinations: - The microcontroller includes a memory space in which is stored a lookup table between, on the one hand, values ​​of injection durations of the second injector and, on the other hand, values ​​of injection durations of the first injector and values ​​of fuel composition. - The unit includes a current sensor connected to the microcontroller and configured to retrieve the injection signal emitted by the computer to the first injector. - The unit includes a temperature probe connected to the microcontroller and configured to measure the temperature of a cylinder head of the engine. - The box includes wireless communication means connected to the microcontroller.

[0008] The invention also relates to a fuel conversion system for an internal combustion engine vehicle, which vehicle includes at least one fuel tank, a computer, at least one first fuel injector fluidly connected to a fuel outlet line from the tank and controllable by the computer, which system includes a conversion unit as described above and a second injector intended to be fluidly connected to the outlet line from the tank and to be controlled by the microcontroller of the conversion unit.

[0009] The system may also include the following optional features, considered individually or in all possible technical combinations: - The second injector is located in an air intake duct of the vehicle's engine upstream of a fuel intake valve in a fuel combustion chamber of said engine.

[0010] The invention finally relates to a method for adjusting the fuel distribution for an internal combustion engine vehicle, which vehicle comprises at least one fuel tank, an electronic control unit (ECU), at least one first fuel injector fluidly connected to a fuel outlet line from the tank and controllable by the ECU, which method is implemented by a conversion system comprising a conversion unit including a microcontroller, which system further comprises a second injector fluidly connected to the outlet line from the tank and controllable by the microcontroller of the conversion unit, which microcontroller is further configured to receive an injection signal emitted by the ECU to the first injector, which conversion unit further comprises a fuel sensor controlled by the microcontroller and fluidly connected to the outlet line from the tank,which process includes a step of determining the fuel composition in the tank from the fuel sensor data, as well as the following steps for each engine cycle: • Determining the injection duration of the first injector from the injection signal data; • Determining the injection duration of the second injector based on the injection duration of the first injector and the determined fuel composition, and • Control of the second injector according to the determined injection duration to deliver an additional quantity of fuel.

[0011] The process may also include the following optional features, considered individually or in all possible technical combinations: - The step of determining the injection duration of the second injector is deduced from a correspondence table between, on the one hand, values ​​of injection durations of the second injector and, on the other hand, values ​​of injection durations of the first injector and values ​​of fuel composition, which table is stored in a memory space of the microcontroller. - The conversion unit includes a temperature probe connected to the microcontroller and configured to measure the temperature of an engine cylinder head, and the process includes the following additional steps • Measurement of the engine cylinder head temperature; • Increase in the injection duration of the second injector by a determined value during each engine cycle if the temperature is below a determined threshold temperature. PRESENTATION OF THE FIGURES

[0012] Other features and advantages of the invention will become clear from the description given below, which is by way of example and not limitation, with reference to the attached figure:

[0013] [Fig. 1] Figure 1 represents a schematic view of the conversion system installed on a vehicle with an internal combustion engine;

[0014] [Fig. 2] Figure 2 represents a schematic view of a detail of the conversion box of the invention;

[0015] [Fig. 3] Figure 3 represents a graph illustrating the injection signal of the first injector and the converted square wave signal used by the microcontroller. DETAILED DESCRIPTION OF THE INVENTION

[0016] It is first clarified that in the figures, the same references designate the same elements regardless of the figure in which they appear and regardless of the form in which those elements are represented. Similarly, if elements are not specifically referenced in one of the figures, their references can easily be found by referring to another figure.

[0017] It is also specified that the figures essentially represent one embodiment of the object of the invention, but that there may be other embodiments which meet the definition of the invention.

[0018] The invention relates to a fuel conversion system 10 for a vehicle with an internal combustion engine.

[0019] Such a vehicle therefore includes a gasoline internal combustion engine – typically running on unleaded E5 or E10 gasoline containing less than 10% ethanol. This type of engine is well known to those skilled in the art and operates cyclically, generally according to a two-stroke or four-stroke cycle.

[0020] Referring to Figure 1, the engine typically comprises one or more piston cylinders enclosed by a cylinder head 22, which defines a combustion chamber 14 in each cylinder for a fuel-air mixture. Each combustion chamber 14 includes a fresh air inlet connected to a fresh air supply duct into the chamber 14 and an exhaust gas outlet connected to an exhaust gas discharge duct out of the chamber 14. Furthermore, the fresh air inlet ducts are all connected to an air intake duct 15, which includes a means for regulating the airflow (not shown) entering said air intake duct 15. This regulating means is commonly known as the "engine throttle body." Moreover, the exhaust ducts are all connected to an exhaust gas discharge duct.Finally, each cylinder includes an intake valve 13 at the inlet of the combustion chamber 14 and an exhaust valve 32 at the outlet of said combustion chamber 14.

[0021] The vehicle also includes at least one first injector 4, typically a plurality of first injectors 4 installed along a rail Injection (not shown). Many configurations of such first injectors 4 are well known to those skilled in the art; for example, but not limited to, the vehicle may have a single first injector 4 located upstream of the engine throttle body (single-point injection), or multiple first injectors 4 (one per cylinder) located downstream of the engine throttle body (multi-point injection). In multi-point injection, in one configuration, the first injector 4 is positioned to inject fuel directly into the combustion chamber 14 (direct injection). In an alternative configuration, the first injector 4 is positioned to inject fuel upstream of the intake valve 13 of the combustion chamber 14 (indirect injection). The terms upstream and downstream are to be understood in relation to the direction of airflow in the air intake duct 15.

[0022] Finally, in the case of a multi-point injection system, the first 4 injectors can operate simultaneously, semi-sequentially or sequentially, depending on the type of engine and engine cycles.

[0023] These configurations of first injectors 4 and their operation are well known to those skilled in the art, and the invention is suitable for any configuration of first injectors 4 and for any operating scheme of said first injectors 4, although Figure 1 represents a single cylinder and a single first injector 4 opening directly into the combustion chamber 14 (direct injection).

[0024] The operation of these first injectors 4 is controlled by a vehicle control unit 3 powered by the vehicle's battery. This control unit 3 is configured to control each first injector 4 via a control cable 21. Typically, the control unit 3 commands the opening of the first injector 4 by sending it an injection signal 26 (Figures 2 and 3) via the control cable 21. The opening time of this injector 4 is calculated to deliver fuel (in this case, the fuel for which the vehicle is originally designed, for example E10 or E5) in stoichiometric proportions to ensure residue-free combustion in the combustion chamber 14. This opening time, determined by the control unit 3, depends in particular on the engine speed and the position of the engine throttle body, but other parameters are often taken into account, notably the temperature of the engine cylinder head 32.

[0025] To supply these first injectors 4 with fuel, the vehicle includes a so-called low-pressure fuel pump (not shown) housed in a fuel tank 2 of the vehicle, and integrated into a fuel distribution circuit connected to said tank 2. This circuit includes a fuel outlet line 5 from the tank 2, opening into the inlet of the first injectors 4, and an inlet line 16 opening into the tank 2 and exiting from said first injectors 4. The low-pressure fuel pump is powered by the vehicle's battery.

[0026] Furthermore, in the embodiment shown in Figure 1, that is, with first injectors 4 operating in direct injection, the vehicle includes a fuel pump 18 which delivers high pressure to supply these injectors 4, typically in the range of 100 to 200 bar. This high-pressure pump 18 is mechanically powered by the rotation of the vehicle's camshafts. The high-pressure pump is integrated into the outlet line 5 of the fuel distribution circuit, upstream of the first injectors 4, the term "upstream" being understood in relation to the direction of fuel flow through the distribution circuit.

[0027] The first four injectors are therefore perfectly suited to operate with a specific fuel. However, if the tank is filled with a fuel having a lower energy density than the fuel originally intended for the vehicle—typically by replacing E10 or E5 unleaded gasoline with E85 superethanol, which is less energy-dense than E10 or E5 gasoline—then the first four injectors no longer supply enough fuel to ensure proper engine operation. More precisely, the air-fuel mixture is no longer stoichiometric, and the cylinders no longer have sufficient energy to complete the engine's combustion cycle.

[0028] According to the invention, the fuel conversion system 10, in particular to bioethanol (or superethanol E85), is integrated into the vehicle to enable it to provide just enough fuel to restore the stoichiometric air-fuel mixture and bring the extra energy needed to complete the engine cycle.

[0029] With reference to Figures 1 and 2, the conversion system includes a second injector 6 opening into the air intake duct 15, upstream or downstream downstream of the engine throttle body. This second injector 6 is therefore configured to operate in indirect injection.

[0030] The second injector 6 is further supplied with fuel by a fuel bypass line 17 connected to the fuel outlet line 5, for example via a T-fitting. This second injector 6 is not only part of the conversion system of the invention 10, but is also part of the vehicle.

[0031] The conversion system 10 further includes a conversion box 1 which includes a programmable microcontroller 7, typically comprising at least one processor, memory space, input / output interfaces and peripheral units 8, 9, 11, 12. The various elements of the conversion box 1 are powered by the vehicle battery, via electrical terminals 25.

[0032] The microcontroller 7 is configured to drive the second injector 6 via a control cable 24.

[0033] Among the peripheral units, the microcontroller 7 includes a current sensor 9 and a fuel sensor 8. Advantageously, the microcontroller 7 includes two other peripheral units: a temperature probe 11 and wireless communication means 12.

[0034] The current sensor 9 is connected to the control cable 21 of the first injector(s) 4. This current sensor 9 is configured to detect the injection signal 26 sent by the vehicle's control unit 3 to the first injectors 4, without altering the signal. An example of this injection signal 26 is represented by the lower curve in Figure 3, which is a graph with elapsed time on the x-axis and signal intensity on the y-axis. The injection signal 26 comprises a flat, monotonic portion 28—indicating that injector 4 is closed—arranged on either side of a non-monotonic signal portion 29 representing the opening command phase of the first injector 4. Thus, the current sensor 9 allows the microcontroller 7 to retrieve the opening, closing, and injection duration commands for the first injector(s) 4.

[0035] The temperature probe 11 is connected to the cylinder head 22 of the engine and allows the microcontroller 7 to determine in real time the temperature of said cylinder head 22.

[0036] Wireless communication methods 12, for example Bluetooth, allow communication with the microcontroller 7 of the conversion box 1 via a computer device such as a personal computer, tablet or smartphone, to read the data from the microcontroller 7 (data received from peripheral units or command data sent to the second injector 6). This wireless link also allows programming of the microcontroller 7 as needed, and in particular the injection strategies of the second injector 6.

[0037] The fuel sensor 8 is connected to the fuel outlet line 5 and is electrically connected to the microcontroller 7 via a connecting cable 23. During measurement, the fuel sensor 8 sends a signal, for example a square wave, to the microcontroller 7. The frequency of this signal is directly correlated to the fuel composition, and in particular to the volume percentage of ethanol in the fuel. To determine this percentage, the microcontroller 7 executes the following formula stored in memory: Ethanol percentage = Signal frequency in Hz - 50.

[0038] The microcontroller 7 is finally configured - at each engine cycle - to generate an injection signal 27 from the second injector and control the opening of said second injector 6 according to a determined duration which is a function of the profile of the injection signal 26 destined for the first injectors 4, the temperature of the cylinder head 22 of the engine and the composition of the fuel.

[0039] This opening time of the second injector 6 (directly correlated to an additional quantity of fuel to be delivered) is determined via a lookup table between, on the one hand, the said injection time of the second injector 6 and, on the other hand, the injection time of the first injectors 4 during an engine cycle (directly correlated to the initial quantity of fuel delivered by the first injectors 4 during an engine cycle) and the composition of the fuel in the tank 2. This lookup table is stored in the memory space of the microcontroller 7 of the conversion box 1. Thus, the conversion system 10 makes it possible to adjust the total quantity of fuel delivered to restore the stoichiometric air-fuel mixture and allow the completion of a full engine cycle.

[0040] According to the invention, a method for adjusting the fuel distribution implemented by the fuel conversion system 10 will now be described.

[0041] When the vehicle starts, the temperature sensor 11 initiates continuous temperature measurement of the engine's cylinder head 22, and the fuel sensor 8 generates a square wave signal whose frequency is correlated to the fuel composition. This signal is sent to the microcontroller 7, which interprets the signal and determines the fuel composition, and in particular the volume percentage of ethanol in the fuel.

[0042] Once the fuel composition is established, the current sensor 9 captures the injection signal 26 emitted by the vehicle's computer 3 to the first injectors 4 and transmits it directly to the microcontroller 7. To facilitate the interpretation of this signal, the injection signal 26 is first converted into a square wave injection signal 33 (upper curve in Figure 3). More precisely, the portion(s) 28 of the injection signal 26 whose intensity is less than or equal to a first determined threshold value correspond to the base 30 of the square wave injection signal 33, while the portion(s) 29 of the injection signal 26 whose intensity is greater than or equal to a second determined threshold value correspond to the peak 31 of the square wave injection signal 33, the second threshold value being greater than the first threshold value.

[0043] The square injection signal 33 is then interpreted by the microcontroller 7 which thus deduces the opening time of the first injectors 44 during an engine cycle, from the width of the peak 31 of the square signal 33.

[0044] In a later step, the microcontroller 7 determines the injection duration of the second injector 6. This is deduced by the microcontroller 7 from the considered correspondence table by identifying the value of the injection duration of the second injector 6 which corresponds to the determined injection duration of the first injector 4 and to the determined composition of the fuel.

[0045] Finally, the microcontroller 7 generates an injection signal 27 from the second injector 6 which passes through the cable 24 to control said second injector 6, so that the latter opens for the duration determined from the correspondence table and delivers the additional quantity of fuel necessary to complete the engine cycle.

[0046] The successive steps of the process of the invention following the step of determining the fuel composition are repeated for each engine cycle.

[0047] In a particularly advantageous way, and in order to improve the operation of the engine at low temperature, and as long as the temperature of the cylinder head 22 of the engine is below a determined value, for example 15 °C, then the microcontroller 7 commands the increase of the injection duration of the second injector 6 by a determined value during each engine cycle, so as to further increase the quantity of fuel distributed by the second injector 6.

[0048] The description of the embodiment relates more specifically to a conversion system for E85-type superethanol for internal combustion engines. initially designed to operate with E10 or E5 type fuels, the conversion system 10 of the invention is adaptable to other fuel types. This simply requires adapting the injection strategies of the second injector 6 via wireless communication means 12, and, if necessary, modifying the lookup table stored in the microcontroller's memory 7. Furthermore, and advantageously, the invention solves the fouling problems of the fresh air intake ducts and intake valves 13 inherent in a direct injection configuration of the first injectors 4. Indeed, adding a second injector 6 to the air intake duct 15 resolves this problem, as the fuel injected by this second injector 6 has a cleaning effect that prevents deposits, such as oil vapors, from passing through the intake air in the air ducts.

Claims

DEMANDS 1. Fuel conversion unit (1) for an internal combustion engine vehicle, which vehicle comprises at least one fuel tank (2), an electronic control unit (ECU) (3), at least one first fuel injector (4) fluidly connected to a fuel outlet line (5) of the tank (2) and controllable by the ECU (3), and at least one second injector (6) fluidly connected to the outlet line (5) of the tank (2) and controllable by a microcontroller (7) of the conversion unit (1), which microcontroller (7) is further provided to receive an injection signal (26) emitted by the ECU (3) to the first injector (4), which conversion unit (1) further comprises a fuel sensor (8) controlled by the microcontroller (7), characterized in that the microcontroller (7) of the conversion unit (1) is configured to determine the composition of the fuel in the tank (2) from the data of the fuel sensor (8), and for each engine cycle: • Determine an injection duration of the first injector (4) from the injection signal data (26); • Determine the injection duration of the second injector (6) from the injection duration of the first injector (4) and the determined fuel composition, and • Control the second injector (6) according to the determined injection duration to deliver an additional quantity of fuel.

2. Housing (1) according to the preceding claim, characterized in that the microcontroller (7) includes a memory space in which is stored a correspondence table between, on the one hand, values ​​of injection durations of the second injector (6) and, on the other hand, values ​​of injection durations of the first injector (4) and values ​​of fuel compositions.

3. Housing (1) according to claim 1 or 2, characterized in that it comprises a current sensor (9) connected to the microcontroller and configured to recover the injection signal (26) emitted by the computer (3) to the first injector (4).

4. Housing (1) according to any one of the preceding claims, characterized in that it comprises a temperature probe (11) connected to the microcontroller (7) and configured to measure the temperature of a cylinder head (22) of the engine.

5. Housing (1) according to any one of the preceding claims, characterized in that it comprises wireless communication means (12) connected to the microcontroller (7).

6. Fuel conversion system (10) for an internal combustion engine vehicle, which vehicle comprises at least one fuel tank (2), a computer (3), at least one first fuel injector (4) fluidly connected to a fuel outlet line (5) of the tank (2) and controllable by the computer (3), which system (10) comprises a conversion unit (1) according to any one of claims 1 to 5 and a second injector (6) intended to be fluidly connected to the outlet line (5) of the tank (2) and to be controlled by the microcontroller (7) of the conversion unit (1).

7. System (10) according to the preceding claim, characterized in that the second injector (6) is disposed in an air intake duct (15) of the vehicle engine upstream of a fuel intake valve (13) in a fuel combustion chamber (14) of said engine.

8. Method for adjusting the fuel distribution for an internal combustion engine vehicle, which vehicle comprises at least one fuel tank (2), an ECU (1), at least one first fuel injector (4) fluidly connected to a fuel outlet line (5) of the tank (2) and controllable by the ECU (3), which method is implemented by a conversion system (10) comprising a conversion unit (1) having a microcontroller (7), which system (10) further comprises a second injector (6) fluidly connected to the outlet line (5) of the tank (2) and controllable by the microcontroller (7) of the conversion unit (1), which microcontroller (7) is further configured to receive an injection signal (26) emitted by the ECU (3) to the first injector (4),which conversion unit (1) further comprises a fuel sensor (8) controlled by the microcontroller and fluidly connected to the outlet line of the tank (2), which method comprises a step of determining the composition of the fuel in the tank from the data of the fuel sensor (8), as well as the following steps for each engine cycle:, • Determination of the injection duration of the first injector (4) from the injection signal data (26); • Determining the injection duration of the second injector (6) from the injection duration of the first injector (4) and the determined fuel composition, and • Control of the second injector (6) according to the injection duration determined to deliver an additional quantity of fuel.

9. A method according to the preceding claim, characterized in that the step of The determination of the injection duration of the second injector (6) is deduced from a correspondence table between, on the one hand, values ​​of injection durations of the second injector (6) and, on the other hand, values ​​of injection durations of the first injector (4) and values ​​of fuel compositions, which table is stored in a memory space of the microcontroller (7).

10. Method according to claim 8 or 9, characterized in that the conversion box (1) comprises a temperature probe (11) connected to the microcontroller (7) and configured to measure the temperature of a cylinder head (22) of the engine, and in that the method comprises the following additional steps: • Measurement of the temperature of the cylinder head (22) of the engine; • Increase in the injection duration of the second injector (6) by a determined value during each engine cycle if the temperature is below a determined threshold temperature.

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