Method for managing misfires in a hydrogen internal combustion engine

Abstract

The invention relates to a method for managing misfires (1) in a hydrogen internal combustion engine for a motor vehicle, the hydrogen internal combustion engine having at least one cylinder, the method comprising a preliminary step (10) of detecting a misfire in the cylinder, followed by additional steps of: Incrementing (40) a misfire counter associated with the cylinder; Evaluating (42) a hydrogen concentration value at the exhaust from the previously incremented misfire counter; If the hydrogen concentration value is greater than a predetermined threshold value, then the method triggers (44) a cut-off of the injection within the cylinder concerned. Figure 1

Description

Title of the invention: METHOD for managing misfires in a hydrogen thermal engine Technical field of the invention

[0001] The invention relates, in general, to the technical field of managing a thermal engine, in particular managing misfires in a hydrogen internal combustion engine. State of the prior art

[0002] Today, within a powertrain of a motor vehicle comprising a conventional internal combustion engine, i.e. one whose energy source is a fossil fuel, a misfire detection strategy is implemented within a computer controlling the powertrain.

[0003] In particular, on internal combustion engines with controlled ignition, this strategy for detecting misfires has been imposed by OBD regulations (acronym for “On Board Diagnostics”) since the Euro3 standard.

[0004] This regulation requires the detection of two types of faults: — a level of misfires resulting in the OBD standard being exceeded on cycle (detection must be done by analyzing the misfire rate over 1000 engine cycles); — a level of misfires resulting in damage to the catalyst due to excessively high temperature (detection must be done by analyzing the misfire rate over 200 engine cycles).

[0005] In the case of a hydrogen internal combustion engine, the two previous points of the ODB regulations also apply. However, for these hydrogen internal combustion engines, there is a life case that must be specifically managed: hydrogen can ignite very easily from 4% concentration in the air. In an already very hot exhaust line, following a misfire, the hydrogen injected by the hydrogen internal combustion engine will end up in the exhaust line and risks generating explosions in the catalyst or more generally in said exhaust line. This has the risks of destruction of mechanical parts, noise (explosion) audible in the motor vehicle and outside the motor vehicle (risk of panic) or even significant after-sales service costs and a significantly damaged brand image. Statement of the invention

[0006] The invention aims to remedy all or part of the drawbacks of the state of the technique, in particular by offering a solution enabling misfire management adapted to hydrogen internal combustion engines.

[0007] To do this, there is proposed, according to a first aspect of the invention, a method for managing misfires of a hydrogen internal combustion engine for a motor vehicle, the hydrogen internal combustion engine comprising at least one cylinder, the method comprising a preliminary step of detecting a misfire in the cylinder, as well as additional steps of: a. Incrementing a misfire counter associated with the cylinder; b. Evaluation of an exhaust hydrogen concentration value from the previously incremented misfire counter; c. If the hydrogen concentration value is higher than a predetermined threshold value, then the process triggers a cut-off of the injection within the cylinder concerned.

[0008] According to one embodiment, the threshold value is approximately 4%.

[0009] According to one embodiment, during step c), the method comprises a step alerting a user of the motor vehicle, concomitant with the injection cut-off step.

[0010] According to one embodiment, the hydrogen internal combustion engine comprising two or more cylinders, the preliminary step of detecting a misfire taking place in one of the cylinders, step a) further comprises an incrementation of a global misfire counter on all the cylinders.

[0011] According to one embodiment, the evaluation of a value of the exhaust concentration is carried out from all of the misfire counters associated with each of the cylinders and from the overall misfire counter.

[0012] According to one embodiment, the misfire counter accumulates the volumes of hydrogen actually injected into the cylinder and having been the subject of a misfire.

[0013] According to one embodiment, the method comprises steps of implementing the ODB regulation.

[0014] According to another aspect of the invention, there is provided a powertrain for a motor vehicle comprising a hydrogen internal combustion engine, and a computer is arranged so as to implement a method having at least one of the preceding technical characteristics.

[0015] According to yet another aspect of the invention, there is provided a motor vehicle comprising a powertrain having one of the preceding technical characteristics. brief description of the figures

[0016] Other characteristics and advantages of the invention will emerge on reading the description which follows, with reference to the appended figures, which illustrate: • [Fig.l]: a flowchart representing a method for managing misfires according to the invention.

[0017] For clarity, identical or similar elements are identified by identical reference signs throughout the figures. DETAILED description of an embodiment

[0018] [Fig.l] illustrates a flowchart representing a misfire management method 1 according to the invention. The misfire management method 1 according to the invention is intended to be implemented by a control and monitoring computer for a powertrain comprising a hydrogen internal combustion engine, this powertrain being able to equip a motor vehicle.

[0019] As for a conventional internal combustion engine using hydrocarbons, such as gasoline or LPG or Natural Gas, the hydrogen internal combustion engine must be supervised by a misfire management process (or "misfire" according to the corresponding Anglo-Saxon terminology) as required by the ODB regulation since the Euro 3 standard. As a reminder, this regulation requires the detection of two types of faults. The first type of fault corresponds to a misfire rate over a cycle, a threshold of which is imposed by the ODB regulation: the analysis is carried out on the misfire rate per 1000 cycles carried out by the thermal engine. The second type of fault concerns a misfire rate which will cause damage to the exhaust line catalyst due to an excessively high temperature resulting from the combustion of fuel, which has been the subject of misfires within the thermal engine, in said exhaust line.For this type of fault, ODB regulations require an analysis of the misfire rate over 200 cycles carried out by the thermal engine.

[0020] The misfire management method 1 according to the invention implements the ODB regulation, because it is intended to be implemented in relation to a hydrogen internal combustion engine, the latter also being a spark-ignition engine like its conventional hydrocarbon counterparts. The hydrogen internal combustion engine comprises at least one cylinder.

[0021] For this, the misfire management method 1 according to the invention comprises a preliminary step 10 of detecting a misfire in the cylinder of the hydrogen internal combustion engine.

[0022] In a step 20, the misfire management method 1 according to the invention evaluates an average of the misfire rate over 1000 engine cycles. For a four-stroke thermal engine, an engine cycle corresponds to two rotations of a crankshaft of the thermal engine, i.e. two top dead centers (TDC) for a piston of the cylinder concerned. Therefore, in practice, the misfire management method 1 according to the invention calculates the misfire rate over 2000 TDC.

[0023] In a step 22, the misfire management method 1 according to the invention determines whether the average misfire rate previously evaluated in step 20 exceeds the threshold imposed by the ODB regulations for this situation. If this is the case, in a step 24, the misfire management method 1 according to the invention precedes the lighting of the fault indicator light, or also called the engine warning light, on the dashboard of the motor vehicle so as to warn a user of said motor vehicle and applies possible degraded operating modes of the hydrogen internal combustion engine.

[0024] In a step 30, parallel to the preceding step 20, the misfire management method 1 according to the invention evaluates an average of the misfire rate over 200 engine cycles, i.e. for 400 TDC for a four-stroke thermal engine. In a step 32, the misfire management method 1 according to the invention then determines whether the average of the misfire rate previously evaluated in step 30 exceeds the threshold imposed by the ODB regulations for this situation. If this is the case, in a step 34, the misfire management method 1 according to the invention precedes an intermittent lighting of the fault indicator light, or also called engine warning light, on the dashboard of the motor vehicle so as to warn a user of said motor vehicle and applies engine torque limitations while proceeding with injection cuts on the cylinder concerned by this exceeding of the threshold in this situation.

[0025] However, it turns out that, for a hydrogen internal combustion engine, a particular life situation must be managed by the misfire management method 1 according to the invention. This life situation was cited in the preamble and concerns the concentration of unburned hydrogen in the exhaust line of the hydrogen internal combustion engine.

[0026] To manage this life situation, the misfire management method 1 according to the invention comprises a series of steps 40 to 44 carried out in parallel with steps 20 to 24, on the one hand, and 30 to 34, on the other hand, previously described in relation to the ODB regulations.

[0027] In a step 40, the misfire management method 1 according to the invention increments a misfire counter associated with the cylinder concerned. Then, in a step 42, the misfire management method 1 according to the invention evaluates a hydrogen concentration value in the exhaust from the misfire counter thus incremented.

[0028] In a step 44, if the hydrogen concentration value is greater than a predetermined threshold value, then the misfire management method 1 according to the invention triggers a cut-off of the injection within the cylinder concerned. The predetermined threshold value is for example 4%. At the same time as the cut-off, the misfire management method 1 according to the invention alerts the user, for example, by lighting up the fault indicator light, or engine warning light.

[0029] In an alternative embodiment of the misfire management method 1 according to the invention, the hydrogen internal combustion engine comprises two or more cylinders. The previously described steps of the misfire management method 1 according to the invention are implemented for each of the cylinders of the hydrogen internal combustion engine. In addition, step 40 comprises the incrementation of a global misfire counter over all of the cylinders of the hydrogen internal combustion engine. Therefore, the evaluation of a value of the exhaust concentration of step 42 is carried out from all of the misfire counters associated with each of the cylinders and from the global misfire counter.

[0030] In an alternative embodiment, the misfire counter accumulates the volumes of hydrogen actually injected into the cylinder and having been the subject of a misfire.

[0031] Naturally, the invention is described in the foregoing by way of example. It is understood that the person skilled in the art is able to carry out different variant embodiments of the invention without departing from the scope of the invention.

[0032] It is emphasized that all features, as they emerge for a person skilled in the art from the present description, the drawings and the attached claims, even if they have been specifically described only in relation to other determined features, both individually and in any combinations, may be combined with other features or groups of features disclosed herein, provided that this has not been expressly excluded or that technical circumstances make such combinations impossible or devoid of sense.

Claims

Claims

1. Method for managing misfires (1) of a hydrogen internal combustion engine for a motor vehicle, the hydrogen internal combustion engine comprising at least one cylinder, the method comprising a preliminary step (10) of detecting a misfire in the cylinder, characterized in that the method comprises additional steps of: a. Incrementing (40) a misfire counter associated with the cylinder; b. Evaluating (42) a hydrogen concentration value in the exhaust from the previously incremented misfire counter; c. If the hydrogen concentration value is greater than a predetermined threshold value, then the method triggers (44) a cut-off of the injection within the cylinder concerned.

2. Method according to claim 1, characterized in that the threshold value is approximately 4%.

3. Method according to one of claims 1 to 2, characterized in that, during step c), the method comprises a step of alerting a user of the motor vehicle, concomitant with the step of cutting off the injection.

4. Method according to one of claims 1 to 3, characterized in that, the hydrogen internal combustion engine comprising two or more cylinders, the preliminary step of detecting a misfire taking place in one of the cylinders, step a) further comprises an incrementation of a global misfire counter on all the cylinders.

5. Method according to claim 4, characterized in that the evaluation of a value of the exhaust concentration is carried out from the set of misfire counters associated with each of the cylinders and from the overall misfire counter.

6. Method according to one of claims 1 to 5, characterized in that the misfire counter accumulates the volumes of hydrogen actually injected into the cylinder and having been the subject of a misfire.

7. Method according to one of claims 1 to 6, characterized in that the method comprises steps (20, 22, 24, 30, 32, 34) of implementing the ODB regulations.

8. Powertrain for a motor vehicle comprising a hydrogen internal combustion engine, characterized in that it further comprises a computer arranged so as to implement the method according to one of claims 1 to 7.

9. Motor vehicle, characterized in that it comprises a powertrain according to claim 8.

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