METHOD FOR CORRECTING A MINIMUM IGNITION SETTING OF AN INTERNAL COMBUSTION ENGINE

Abstract

The invention relates to a method for correcting a minimum ignition setting (1) of an internal combustion engine of a motor vehicle powertrain, the internal combustion engine having an exhaust gas outlet, characterized in that the method comprises steps of: Analyzing (11) an exhaust temperature (2) at the exhaust gas outlet; Determining (12) a temperature delta between the previously analyzed exhaust temperature and a predetermined maximum exhaust temperature; Determining (13) a correction factor from the previously determined temperature delta; and, Calculating (14) a limit of the minimum ignition setting (4) as a function of the previously determined correction factor. Figure 1

Description

Title of the invention: Method for correcting a minimum setting of the ignition of an internal combustion engine Technical field of the invention

[0001] The invention relates, in general, to the technical field of controlling an internal combustion engine. In particular, the invention relates to a method for correcting a minimum ignition setting of an internal combustion engine. State of the prior art

[0002] Today, an exhaust temperature of an internal combustion engine is ensured by a minimum ignition setting. For this, a single two-dimensional map is configured in order to provide protection against ignition. This two-dimensional map is defined taking into account two requirements: combustion stability within the internal combustion engine (a minimum stability is required for a drive constraint) and an exhaust hydrocarbon rate (for an exhaust gas emission constraint). Control of the exhaust temperature is important for protection of the exhaust line and / or the turbocharger.

[0003] In current systems, the minimum ignition setting of an internal combustion engine has the disadvantage of generating too high an engine torque. It is difficult to obtain a low engine torque associated with an exhaust temperature below the maximum assigned temperature. The two-dimensional mapping alone requires a high minimum ignition setting to ensure robust exhaust protection, hence the high engine torque of the internal combustion engine. The second disadvantage is an activation of an injection cut-off (single injection or multiple injections) which degrades the stability of the engine torque of the internal combustion engine as well as the exhaust gas emissions. Statement of the invention

[0004] The invention aims to remedy all or part of the drawbacks of the state of the art by proposing in particular a solution allowing.

[0005] To do this, there is proposed, according to a first aspect of the invention, a method for correcting a minimum ignition setting of an internal combustion engine of a motor vehicle powertrain, the internal combustion engine comprising an exhaust gas outlet, the method comprising steps of: a. Analyzing an exhaust temperature at the exhaust gas outlet; b. Determination of a temperature delta between the previously analyzed exhaust temperature and a predetermined maximum exhaust temperature; c. Determination of a correction factor from the previously determined temperature delta; and, d. Calculation of a minimum ignition timing limit based on the previously determined correction factor.

[0006] According to one embodiment, the correction factor is a barycentric correction factor.

[0007] According to one embodiment, the determination of the correction factor is based on an interpolation between two high and low maps of minimum ignition adjustment.

[0008] According to one embodiment, the high and low maps are determined from engine load information of the internal combustion engine.

[0009] According to one embodiment, the high and low maps are determined from information on the rotation speed of the internal combustion engine.

[0010] According to one embodiment, during step a), following the analysis of the exhaust temperature, steps c) to d) are only triggered if the determined exhaust temperature is greater than a predetermined threshold value.

[0011] According to another aspect of the invention, there is provided a powertrain for a motor vehicle comprising an internal combustion engine, as well as a computer which is arranged so as to implement a method for correcting a minimum ignition setting according to the invention having at least one of the preceding technical characteristics

[0012] 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

[0013] Other characteristics and advantages of the invention will emerge on reading the description which follows, with reference to the appended figures, which illustrate: • [Fig-1]: a flowchart illustrating a method for correcting an ignition setting of an internal combustion engine according to the invention; • [Fig.2]: a graph illustrating, in a timing diagram, an example of correction of a minimum ignition setting obtained by implementing the process illustrated in [Fig.l].

[0014] For clarity, identical or similar elements are identified by identical reference signs throughout the figures. DETAILED description of an embodiment

[0015] [Fig. 1] illustrates a flowchart of a preferred embodiment of a method for correcting a minimum ignition setting 1 of an internal combustion engine according to the invention.

[0016] The method for correcting a minimum ignition setting 1 of an internal combustion engine according to the invention comprises, here, a first step 11 of analyzing an exhaust temperature 2 at an exhaust gas outlet of the internal combustion engine. An exhaust temperature profile 20 is calculated, like that illustrated in [Fig.2]. The exhaust temperature thus analyzed is compared to an exhaust temperature threshold value Ts. If the analyzed exhaust temperature is below the threshold value Ts, the method for correcting a minimum ignition setting 1 of an internal combustion engine according to the invention continues the analysis of the exhaust temperature 2.

[0017] Otherwise, if the analyzed exhaust temperature, at a time t0 exceeds the threshold value Ts, the method for correcting a minimum ignition setting 1 of an internal combustion engine according to the invention moves on to a step 12 of determining a temperature delta A between the previously analyzed exhaust temperature and a predetermined maximum exhaust temperature Tmax.

[0018] Then, the method for correcting a minimum ignition setting 1 of an internal combustion engine according to the invention comprises a step 13 of determining a correction factor from the previously determined temperature delta A. The correction factor is, here, a barycentric factor. For this, the determination of the correction factor also takes into account two high 131 and low 132 maps of minimum ignition setting. Each of the high 131 and low 132 maps of minimum ignition setting is developed from, on the one hand, information on the speed of the internal combustion engine, in particular a rotational speed of a crankshaft of the latter, and, on the other hand, information on the load of said internal combustion engine, in particular a torque supplied by said internal combustion engine.Thus, the correction factor is based on an interpolation between the two high 131 and low 132 maps of minimum ignition adjustment.

[0019] Then, the method for correcting a minimum setting of the ignition 1 of an internal combustion engine according to the invention comprises a step 14 of calculating a limit of the minimum setting of the ignition 4 as a function of the previously determined correction factor. Thus, the limit of the minimum setting of the ignition 4 is between a lower limit L-Imin and an upper limit H-Imin of the minimum setting of the ignition 4.

[0020] This is exemplified by curve 40 in the timing diagram of [Fig.2]. In particular, at the instant t0 where the analyzed exhaust temperature exceeds the threshold value Ts, the limit of the minimum ignition setting 4 is equal to the lower limit L-Imin. Then as the temperature delta D decreases, the limit of the minimum ignition setting 4 increases to reach the upper limit H-Imin when the analyzed exhaust temperature 4 reaches a maximum exhaust temperature Tmax, at time t2. Mainly by inertia, the exhaust temperature 2 exceeds this maximum exhaust temperature Tmax and then returns, from time t3, below the maximum exhaust temperature Tmax. Between times t2 and t3, the limit of the minimum ignition setting 4 remains at the value of the upper limit H-Imin. From time t3, the limit of the minimum ignition setting 4 decreases as the analyzed exhaust temperature 2 decreases.

[0021] Also illustrated in [Fig.2], an evolution 5 of an engine torque of the internal combustion engine obtained with the method for correcting a minimum ignition setting 1 of an internal combustion engine according to the invention is associated, for purely illustrative purposes, with the exhaust temperature profile 20. By implementing the method for correcting a minimum ignition setting 1 of an internal combustion engine according to the invention, before time t0, while the internal combustion engine is in a state where the limit of the minimum ignition setting 4 is at the value of the lower limit, a first minimum torque 51 can be obtained in this situation. Between times t2 and t3, it is possible to obtain a second minimum torque 52. The two minimum torques 51 and 52 are, here, on a minimum torque profile 50 achievable by the internal combustion engine in operation.It should be noted that this minimum torque profile 50 follows the evolution 40 of the limit of the minimum ignition setting 4. .

[0022] In order to implement the method for correcting a minimum ignition setting 1 of an internal combustion engine according to the invention within a powertrain, the latter, comprising an internal combustion engine, also comprises a computer arranged for this purpose. The internal combustion engine may be a gasoline or diesel thermal engine. The powertrain may be a hybrid powertrain comprising, in addition to the internal combustion engine, one or more electric machines.

[0023] The implementation of a method for correcting a minimum ignition setting 1 of an internal combustion engine according to the invention to control an operation of an internal combustion engine makes it possible to obtain better control of the engine torque of said internal combustion engine because a lower engine torque is possible when the exhaust temperature is low: the torque range is greater when the exhaust temperature is below the maximum limit thanks to the low minimum ignition setting thus calculated by the method according to the invention. Additionally, the internal combustion engine exhaust system, particularly the turbocharger and catalyst, is properly protected with less compromise on the minimum engine torque expected for powertrain management, drivability and exhaust emissions. Furthermore, the elimination of fuel injection cuts leads to better torque management and lower exhaust emissions.

[0024] 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.

[0025] 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 concretely they have only been described 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 meaningless.

Claims

Claims

1. Method for correcting a minimum ignition setting (1) of an internal combustion engine of a motor vehicle powertrain, the internal combustion engine having an exhaust gas outlet, characterized in that the method comprises steps of: a. Analyzing (11) an exhaust temperature (2) at the exhaust gas outlet; b. Determining (12) a temperature delta (A) between the previously analyzed exhaust temperature and a predetermined maximum exhaust temperature (Tmax); c. Determining (13) a correction factor from the previously determined temperature delta; and, d. Calculating (14) a limit of the minimum ignition setting (4) as a function of the previously determined correction factor.

2. Method according to claim 1, characterized in that the correction factor is a barycentric correction factor.

3. Method according to one of claims 1 to 2, characterized in that the determination of the correction factor is based on an interpolation between two high (131) and low (132) maps of minimum ignition adjustment.

4. Method according to claim 3, characterized in that the high and low maps are determined from engine load information of the internal combustion engine.

5. Method according to one of claims 3 and 4, characterized in that the high and low maps are determined from information on the rotation speed of the internal combustion engine.

6. Method according to one of claims 1 to 5, characterized in that during step a), following the analysis of the exhaust temperature, steps c) to d) are only triggered if the determined exhaust temperature is greater than a predetermined threshold value (Ts).

7. Powertrain for a motor vehicle comprising an internal combustion engine, characterized in that it further comprises a computer which is arranged so as to implement a

8. method for correcting a minimum ignition setting according to one of claims 1 to 6. Motor vehicle, characterized in that it comprises a powertrain according to claim 7.

Images