Method for preheating an after-treatment device

Abstract

Disclosed is a preheating method for controlling the rise in temperature of an after-treatment device (100) of a motor vehicle that is driven at least partially by an internal combustion engine, characterised in that the preheating method comprises a step (6) of pre-heating the after-treatment device (100) at a threshold heating power level (22, 44) and at least one cycle (40, 42) following the pre-heating step (6), this cycle (40, 42) comprising a step (7, 8) of detecting a user activity included in a list of key activities representing a desire (103) to start up the vehicle and a step (9, 10) of increasing the heating power level to a higher heating power level when a key activity representing a desire (103) to start up the vehicle is detected.

Description

[0001] DESCRIPTION

[0002] METHOD FOR PREHEATING A POST-TREATMENT DEVICE

[0003] The present invention relates to the field of pollution control of vehicles which are powered at least in part by an internal combustion engine, i.e. for example a hybrid vehicle or a pure thermal vehicle. The invention relates more particularly to a method for preheating a device for post-treatment of the polluting emissions of such an engine, configured to control the rise in temperature of a post-treatment device.

[0004] Car manufacturers are seeking to reduce pollutant emissions from internal combustion engines, including emissions of unburned hydrocarbons (HC), nitrogen oxides (NOx) and nitric oxide (CO), as well as emissions of carbon dioxide (CO2), a greenhouse gas, across their ranges of vehicles powered at least in part by such internal combustion engines.

[0005] A known way to reduce the release into the outside atmosphere of polluting molecules contained in the combustion gases of these engines is to add post-treatment devices to the vehicle's exhaust system, for example these systems can be exhaust catalysts, which treat the exhaust gases, in particular three-way catalysts in the case of gasoline engines which allow the oxidation of unburned hydrocarbons and carbon monoxide, and the reduction of nitrogen oxides. The catalysts currently present on vehicles on the market require, in order to be at their maximum capacity, that is to say, to achieve sufficient efficiency in converting polluting molecules into more harmless molecules, to reach a certain temperature, which can be called the ignition temperature. In general, the temperature necessary for the proper functioning of a catalyst is approximately 450°C.

[0006] It is therefore appropriate to carry out a preheating operation of the post-treatment device on board a vehicle in order to aim for a triggering temperature of this post-treatment device as soon as possible after starting the vehicle. As is known, to carry out this preheating operation, manufacturers add electrical devices, for example heating grids, to the catalysts. These grids allow the catalyst to increase in temperature.

[0007] The electrical energy used to make the pollution control systems efficient via these preheating methods is drawn from a battery, which naturally has a certain storage capacity.

[0008] As mentioned, it is known to carry out a preheating operation so that the catalyst is effective as soon as the vehicle is started, and it is known to anticipate this preheating operation so that the user is not forced to wait unreasonably before starting his vehicle. The preheating operation is launched at a determined time, this time being for example when the user approaches the vehicle.

[0009] Conventionally, it is intended that the user starts the vehicle and its combustion engine directly after this preheating phase of the post-treatment device. Following this, the battery can be recharged by an alternator or a system of this type. This system is known from the prior art, in particular in document US5155995A.

[0010] A disadvantage of such a system is the risk that the preheating of the post-treatment device is carried out while the vehicle powered at least in part by an internal combustion engine is not subsequently started. This can typically be the case when the user follows the classic steps of a start (unlocking the vehicle, getting into the driving position, etc.), but without going as far as starting the vehicle. The battery cannot then be recharged as planned in the classic scenario. This scenario carried out repeatedly will tend to draw a lot of energy from the battery, which implies a critical decrease in the battery level and a long-term reduction in the preheating capacity.

[0011] The present invention aims to propose a solution to the technical problem set out above by proposing a method for preheating a post-treatment device making it possible to adapt the temperature rise according to the upcoming operating mode. Such a method makes it possible to optimize the preheating of a post-treatment device.The present invention thus aims at a preheating method intended to control the rise in temperature of a post-treatment device of a vehicle powered at least in part by an internal combustion engine, characterized in that the preheating method comprises a step of launching preheating of the post-treatment device to a threshold heating power level, and at least one cycle following the launching step, this cycle comprising a step of detecting a user action included in a list of key actions representative of a desire to start the vehicle, and a step of increasing the heating power level to a higher heating power level when a key action representative of a desire to start the vehicle is detected.

[0012] The launch step is triggered by the detection of a predefined situation, revealing a desire to use the vehicle. This predefined situation may consist of a relationship between the vehicle and the user, for example when the user approaches the vehicle and their remote opening key is detected, or their telephone, or even when the user brings their hand close to the handle. Sensors specific to the detection of this predefined situation may be used, or sensors already fitted to the vehicle. The predefined situation may also consist of a specific moment, for example in the case of triggering the launch step on a daily basis. This specific moment may be configured in the system or acquired as the vehicle is used, for example if the vehicle is unlocked every day at a certain time.

[0013] It should be noted that the predefined situation is indicative of a desire to use the vehicle, i.e. for example a desire or action to enter the vehicle or an action of the user sitting on the driver's seat of the vehicle, but that it is not representative of a desire to start.

[0014] Such an action representative of a desire to start is considered according to the invention during a cycle following the launching step, and in which at least one step of detecting this action and a step of increasing the temperature of the post-treatment device takes place. The detection step implements means capable of detecting one or more key actions listed in a list of key actions representative of a desire to start. These key actions representative of a desire to start are detected by means capable of detecting one or more actions of the user in connection with the vehicle. For example, the fact of fastening one's seat belt may be provided as a key action representative of a desire to start.

[0015] As discussed, the increase step increases the heating power level to an intermediate level, approaching, or reaching, the maximum heating power level.

[0016] The method comprises at least one cycle following the launch step, but it should be noted that it may comprise several successive cycles, with the end of the increase step of a first cycle corresponding to the triggering of the detection step of a following cycle, these successive cycles each comprising an intermediate heating power level, the intermediate heating power level of a cycle being higher than the heating power level of the previous cycle or the threshold heating power level. The succession of these cycles allows in particular that the heating power level reaches the maximum heating power level in successive stages.

[0017] The preheating of the post-treatment device is carried out by a thermal system, for example an electric heating grid, which is powered by a battery. It is understood that the maximum heating power level corresponds to an operating mode in which the thermal system provides the maximum thermal energy that it is capable of providing.

[0018] Advantageously, the preheating method implements a start step and at least one cycle comprising at least one detection step which takes into account a user action and an increase step. Such a configuration of the preheating method, with an increase in the thermal power level in successive stages, makes it possible to better understand cases where the user departs from a conventional vehicle start-up pattern and decides not to start or to delay the start of the vehicle while he is present in the passenger compartment, and thus makes it possible to avoid a maximum of energy losses with complete preheating of the post-treatment device which would be useless. The energy losses will be limited to the stage, or intermediate heating power level, reached by the system.In other words, such a step-by-step increase in the heating level makes it possible to approach the maximum power level, to make the post-treatment device effective if the vehicle is started, but it offers the possibility of realizing that the user will delay or cancel the launch of the vehicle while the level reached during pre-heating is not yet maximum, which makes it possible to save energy consumed by the thermal system. This process thus makes it possible to slow down battery wear and reduce energy consumption, since the alternator will have a lower energy load to provide to the battery at the time of starting. To the extent that the alternator draws the energy necessary to recharge the battery from the internal combustion engine, this thus makes it possible to reduce the fuel consumption of said engine, and therefore its carbon dioxide emissions, which are a greenhouse gas.

[0019] According to another characteristic of the invention, the at least one cycle is a final cycle with a final detection step and a final increase step at the end of which the heating power level is equal to a maximum heating power level.

[0020] In other words, the final cycle is the last cycle carried out by the preheating method and this final cycle makes it possible to reach the maximum heating power level which represents the maximum thermal energy that the thermal system can provide. According to the invention, this final cycle is not immediately triggered but it follows at least the progress of a launch step which has participated in raising the heating power to a threshold value, so that if the key action representing the desire to start which must be detected during the final detection step is not detected, the maximum heating power is not triggered and an energy saving is achieved.

[0021] According to another characteristic of the invention, a plurality of successive cycles are implemented after the launch step, with at least one intermediate cycle taking place between the launch step and the final cycle, the intermediate cycle comprising an intermediate detection step and an intermediate increase step making it possible to increase the heating power level from the threshold heating power level to an intermediate heating power level. It is understood that an intermediate heating power level is of a value greater than the threshold heating power level and of a value less than the maximum heating power level.In the case of a plurality of intermediate cycles, a plurality of intermediate heating power levels may be successively reached during the process, the intermediate heating power levels being distinct from one another to form a stepwise increase in the heating level, with an intermediate heating level reached at the end of an intermediate step which is higher than the intermediate heating level which was reached at the start of this intermediate step.

[0022] The number of intermediate cycles and the type of key action representing the start-up intention which triggers such an intermediate cycle are defined in advance by the manufacturer, each intermediate cycle having its own intermediate heating power level.

[0023] In a first case, the preheating process may not include any intermediate cycle, the process then comprising only a launch step and a final cycle. In this case where only one cycle takes place after the launch step, namely the final cycle, the increase step is such that the intermediate level mentioned is equal to the maximum heating power level.

[0024] In a second case, the preheating method may comprise at least one intermediate cycle, the preheating method then comprising a launch step, one or more intermediate cycles and finally a final cycle. In this case where several cycles including the final cycle follow one another after the launch step, the increase step is such that the intermediate level mentioned tends to approach the maximum heating power level by successively increasing the heating power level from the threshold heating power level reached after the launch step to the maximum heating power level, with a plurality of intermediate heating power levels following one another.

[0025] According to an optional feature of the invention, a predefined situation which can be at the origin of the launch step consists of a detection of the proximity of the user in relation to the vehicle.

[0026] According to an optional characteristic of the invention, a key action representative of a desire to start the vehicle which can be detected in an intermediate cycle consists of an action relating to the positioning of the user in contact with or within the vehicle, such as for example the opening of a door of the vehicle, or the presence in the driver's seat.

[0027] The key actions representing a start-up intention and whether they represent the launch of an intermediate cycle or a final cycle are defined by the manufacturer. A database groups together all the key actions representing a start-up intention, this database being associated with a control unit for piloting the thermal system. The key actions representing a start-up intention are implemented by the manufacturer in the database. The key actions representing a start-up intention are associated with a heating power level of the thermal system associated with the post-treatment device, and the value of this heating power is chosen according to the proximity of the key action associated with the actual start of the vehicle.More specifically, the heating power levels corresponding to actions assumed to be very close chronologically to the actual starting of the vehicle are high and close to the maximum heating power level, while the heating power levels corresponding to actions assumed to be chronologically distant from the actual starting of the vehicle are low, while being higher than the threshold heating power level to achieve the stepwise increase. An action representative of a starting intention considered to be the least close to starting may, for example, consist of opening the door, while an action representative of a starting intention considered to be the closest to actual starting may, for example, consist of detecting a user gesture towards a starting device.Ordering the key actions representative of a desire to start makes it possible to gradually approach the maximum heating power level, while avoiding generating the maximum heating power level for a key action representative of a desire to start which is not closest to starting, for example opening the driver's door, which makes it possible to limit the number of cases where the maximum heating power is delivered while the user ultimately does not start his vehicle. According to another characteristic of the invention, the key action representative of a desire to start the vehicle which can be detected in the final cycle consists of the position of the hand in the area of ​​a vehicle starting device.

[0028] Alternatively, the last key action representative of a starting intention, i.e. the representative key action that can be detected in the final cycle, may be distinct from an action associated with the starting device and may consist, for example, of a user action on the clutch or the brake before starting. The last key action representative of a starting intention is chosen by the manufacturer.

[0029] According to another characteristic of the invention, a verification step is configured to control the effective starting of the vehicle, for a predetermined period of time and starting when the maximum heating power level is reached.

[0030] In other words, following the final cycle, a verification step is initiated, for a period of time that is previously chosen by the manufacturer, and which can be adjusted according to the user's learning practices for starting the vehicle. During this period of time, if the starting device is activated, the preheating process stops.

[0031] According to another characteristic of the invention, the verification step comprises detecting the temperature of the post-treatment device in the case where the actual start-up is not detected. It is thus detected whether the post-treatment device has reached its start-up temperature.

[0032] The invention also relates to a preheating system configured to implement a preheating method as previously mentioned, intended to control the rise in temperature of a post-treatment device of a vehicle powered at least in part by an internal combustion engine, the preheating system comprising at least one thermal system configured to increase the temperature of the post-treatment device, a detection means configured to detect a key action representative of a desire to start the vehicle, a control unit configured to control an increase in the heating power level of the thermal system as a function of the detection of said key action. The preheating system comprises at least one thermal system such as a heating grid configured to provide heat, due to an appropriate electrical power supply, to the post-treatment device.

[0033] The preheating system comprises a control unit configured to modify the heating power level allocated to the thermal system as a function of information detecting a desire to start, the information detecting a desire to start being a key action representative of a desire to start included in a database of the control unit.

[0034] The post-treatment device may in particular be included on at least a portion of the vehicle's exhaust.

[0035] According to another characteristic of the invention, the detection means comprises at least one heterodyne sensor configured to detect a presence in an area close to a starting device, by voltage difference across the terminals of the sensor.

[0036] The preheating system includes at least one heterodyne sensor configured to establish a distance between the sensor and the driver's hand, the position of the hand cannot be known, this detection provides a sphere of possible position of the hand. This detection can make it possible to detect the direction of a hand and therefore the will of an action.

[0037] According to another characteristic of the invention, three heterodyne sensors are positioned at a distance from each other around the area of ​​the starting device.

[0038] The preheating system may include three heterodyne sensors configured to establish a position of the hand in space. This position is established by triangulating the information on the presence of the user's hand in a detection zone common to the sensors.

[0039] Other characteristics, details and advantages of the invention will emerge more clearly on reading the description which follows on the one hand, and examples of embodiment given for informational and non-limiting purposes with reference to the appended drawings on the other hand, in which: [Fig. i] is the schematic representation of the components of a preheating device necessary for the temperature rise of the post-treatment device, according to a preheating method in accordance with the invention;

[0040] [Fig. 2] is a flowchart representing the preheating method of a post-treatment device according to a first embodiment of the invention;

[0041] [Fig. 3] graphically illustrates the evolution of the heating power as a function of the desire to start the vehicle in the preheating process represented by the flowchart in Figure 1;

[0042] [Fig. 4] is a flowchart representing the preheating method of a post-treatment device according to a second embodiment of the invention;

[0043] [Fig. 5] graphically illustrates the evolution of the heating power as a function of the desire to start the vehicle in the preheating process represented by the flowchart in Figure 3;

[0044] [Fig. 6] illustrates an alternative embodiment of means for detecting the desire to start the vehicle by diagramming the interior of a vehicle equipped with a heterodyne sensor configured to detect a desire to start the vehicle and used in the preheating method according to the invention;

[0045] [Fig. 7] illustrates an alternative embodiment of the means for detecting the vehicle's desire to start by diagramming the interior of a vehicle equipped with three heterodyne sensors configured to detect the position of an object in space.

[0046] The features, variants and different embodiments of the invention may be combined with each other in various combinations, provided that they are not incompatible or mutually exclusive. In particular, variants of the invention may be conceived comprising only a selection of features described below in isolation from the other features described, if this selection of features is sufficient to confer a technical advantage and / or to differentiate the invention from the prior art.

[0047] The invention relates to a preheating device for a post-treatment device of a motor vehicle. In order to comply with the anti-pollution standards for vehicles powered at least in part by an internal combustion engine, which are increasingly strict, it is necessary for car manufacturers to find ways to reduce the quantity of polluting molecules (HC, CO, NOx, etc.) that their vehicles can produce. To do this, post-treatment devices such as catalysts are present on the exhaust circuits, making it possible to reduce the release of these pollutants into the outside atmosphere, by filtering the combustion gases emitted by the vehicles' engines. Furthermore, manufacturers are seeking to minimize the release of CO2, a normal product of engine combustion, which is a greenhouse gas.

[0048] The post-treatment device also comprises a thermal system whose function is to increase the temperature of the post-treatment device, if necessary without starting the vehicle, and to carry out a preheating operation so that the post-treatment device is at an optimal operating temperature as soon as the vehicle is started, for example of the order of 450°C. The thermal system may be electrical equipment, powered by an electric battery of the vehicle, such as a heating grille.

[0049] Figure i illustrates a preheating system of a post-treatment device according to the invention, configured to implement the preheating method which will be described subsequently.

[0050] The preheating system of a post-treatment device 100 comprises in particular a thermal system and a control unit 102, in particular configured to control the thermal system 101, and it also comprises a detection means 104, capable of detecting a key action AC representative of a desire to start and of communicating with the control unit 102.

[0051] The control unit 102 is configured to control the thermal system 101. More particularly, according to the invention, the control unit 102 is configured to, on the one hand, generate the ignition of the thermal system 101 and therefore a step of launching the preheating method of the post-treatment device 100, and on the other hand, control the level of heating power generated by the thermal system 101.

[0052] An advantage of the invention is to modulate the temperature rise of the post-treatment device 100 during the preheating step in order to ensure that the post-treatment device 100 is at the correct temperature when the vehicle is started to ensure its effectiveness, while avoiding use cases where the thermal system is supplied at full power so that it delivers maximum heat to the post-treatment device 100 while the vehicle is ultimately not started.

[0053] The control unit 102 may be specific to the thermal system 101 of the invention and exclusively dedicated to the control of the thermal system 101 allowing the preheating of the post-treatment device 100. Alternatively, the control unit 102 may be integrated into the central computer of the vehicle.

[0054] The control unit 102 comprises in memory a database, in which is implemented a list of key actions representative of a starting intention 103, said database also being implemented a heating power level of the thermal system 101 associated with each key action AC representative of a starting intention. In other words, the control unit generates a control instruction of the thermal system, at a given heating power level, as a function of the representative key action AC detected and identified by the control unit. The number of key actions representative of a starting intention present in the list implemented in the database is chosen by the manufacturer and can thus vary from one vehicle application to another.

[0055] The detection means 104 is configured to detect the occurrence of a key action AC representative of a desire to start. A specific detection means is necessary for each key action representative of a desire to start. The detection of key actions representative of a desire to start can also be implemented by reusing detection means already present on the vehicle, such as for example the seat presence sensors.

[0056] As will be described below, such operation of the control unit allows the triggering of intermediate heating power levels for a gradual increase in the temperature of the post-treatment device 100, with in particular a heating level which goes from a threshold heating level obtained after a launch step, allowing a first phase of temperature increase, to a maximum heating level obtained after a final cycle. According to one embodiment, the control unit only includes in its database a key action representative of a desire to start and the preheating method then only includes the launch step and the final cycle launched by the detection of this single key action. By way of non-limiting example, as will be detailed below, this single key action representative of a desire to start may be the presence of the driver's hand near the starting device 2.According to another embodiment, the control unit comprises in its database a plurality of key actions representative of a desire to start, which requires a plurality of detection means. The various representative key actions and the associated detection means are chosen by the manufacturer, depending on the presence of these detection means on the vehicle and / or depending on the relevance of the action considered to represent a desire to start. The preheating method then comprises the launch step, the final cycle which can again be initiated by the detection of the presence of the driver's hand near the start button, and at least one intermediate cycle which can be generated by the detection of other key actions.

[0057] The occurrence of a predefined situation initiates the step of launching the preheating process, this predefined situation being able to be either an automatic situation, daily for example, or a situation occurring more or less remotely from the vehicle, such as for example the launching of preheating by the user via an appropriate application.

[0058] Key actions representative of a desire to start may be, but not limited to, a link between the user and the vehicle when the user is outside the vehicle, such as for example an action by the user on the vehicle key or the detection of the user's hand in the vehicle handle, or a link between the user and the vehicle such as the opening of a vehicle door, or the presence of the user on one of the vehicle's seats.

[0059] The detection means used to detect these key actions can be means specifically dedicated to these detections or already existing means, such as an open door detection sensor already present on the majority of current vehicles, a seat belt detection sensor or a pressure sensor present in the driver's seat.

[0060] It should be noted that each of the actions just given as an example as a key action representative of the start-up desire could also form the predefined situation as previously mentioned, namely the situation which triggers the start-up step of the preheating process.

[0061] Figure 1 also illustrates a succession of steps of the preheating method according to one aspect of the invention, implemented by the preheating device as just described. When a key action AC representative of a desire to start is detected by the detection means 104, the detection information is sent to the control unit 102. The control unit 102 analyzes the relevance of the data received, in particular by comparing the detection information with the list of representative key actions 103 stored in the database associated with the control unit 102. The control unit then identifies the representative key action and the associated heating power level. After this analysis, the control unit 102 communicates the heating power level modification instructions to the thermal system 101, in order to allow the modification of the temperature of the post-treatment device 100.

[0062] Figures 2 and 3 illustrate more particularly a first embodiment of the preheating method during which two main steps take place, including a launch step 6 and a final cycle 40 comprising a final detection step 7 and a final increase step 9 of the heating power level of the thermal system.

[0063] As illustrated in the flowchart in Figure 2, the preheating process begins with the start step 6, initiated by the occurrence of a predefined situation. The start step allows the heating power level of the thermal system to be brought to a threshold power level.

[0064] The launch step is followed in this first embodiment of the preheating method by the final cycle 40, which begins with the final detection step 7 as just mentioned. If there is non-detection 23 of the key action AC representing a desire to start, then the heating power level does not change and a new final detection step 7 is initiated. If there is detection 24 of the key action AC representing a desire to start, then the final increase step 9 is initiated and the control unit controls the thermal system to bring it to a maximum heating power level 26. Figure 3 illustrates the evolution of the heating power level of the thermal system 101 during the preheating method, here expressed as a percentage of the maximum heating level, with in particular a threshold heating level 22 and a maximum heating level 26.Curve 20 is representative of the temperature of the post-treatment device 100 as a function of the time since the start of the preheating process and the heating power level.

[0065] As can be seen in Figure 3, the start step 6 is such that the control unit 102 controls the thermal system 101 so that it operates at a threshold heating level 22, here of the order of 40% of the maximum heating power of the thermal system, so that the temperature of the post-treatment device 100 increases gradually over time, according to a first notable increase 28 on the curve 20. When the key action representative of a desire to start is detected during the final detection step 7 initiating the final cycle 40, the final increase step 9 triggers the increase in the heating power level to the maximum level 26. The temperature of the post-treatment device 100 therefore increases more quickly over time, to form the final increase slope 30 visible on the curve 20, which brings the post-treatment device 100 to the desired temperature.The final cycle 40 in this method is represented by the succession of the final detection step 7 and the final augmentation step 9.

[0066] Figures 4 and 5 illustrate a second embodiment of the preheating method which here comprises at least 3 major steps including a launch step 6 and a final cycle 40 similar to what has been described, as well as at least one intermediate cycle 42 between the launch step and the final cycle and comprising an intermediate detection step 8 and an intermediate increase step 10.

[0067] As illustrated in the flowchart in Figure 4, the preheating method according to the second embodiment begins, as in the first embodiment, with the start step 6, again initiated by the occurrence of a predefined situation and which brings the heating power level to a threshold power level 22, which forms a first heating power increase level. Unlike the first embodiment, the start step is not directly followed by the final cycle 40 but by at least one intermediate cycle 42 between the start step 6 and the final cycle 40. Each of the intermediate cycles makes it possible to raise the heating power level of the thermal system in stages, from the threshold power level 22 to the maximum power level via intermediate power levels.

[0068] The launch step is thus followed in this second embodiment of the preheating method by an intermediate cycle 42, which begins with an intermediate detection step 8. If there is no detection 32 of a key action AC representing a desire to start, then the heating power level does not change and a new intermediate detection step 8 is initiated. If there is detection 34 of the key action AC representing a desire to start, then the intermediate increase step 10 is initiated and the control unit controls the thermal system to bring it to an intermediate threshold level 44.The succession of the intermediate detection step 8 and the intermediate increase step 10 thus forms an intermediate cycle 42 specific to this second embodiment which can be followed either by another intermediate cycle, with a new intermediate detection step which follows said intermediate increase step and a new increase step.

[0069] The or one of the intermediate cycles 42 is extended by the final cycle 40 as soon as the detection 34 of a key action AC representative of a desire to start concerns the key action AC present in the list 103 which has been judged by the manufacturer to be the closest to an effective start of the vehicle. In accordance with what has been described previously, the final cycle 40 is triggered by bringing the heating power level of the thermal system to the maximum power level 26.

[0070] The second embodiment as just mentioned is also notable in that it includes a verification step 46, which is launched when the maximum heating power level 26 is reached.

[0071] The verification step 46 consists of a control phase during which it is verified that the starting of the vehicle is effective, for example by verifying that an action is performed on the starting device 2 for example, such as turning the vehicle key, and this for a defined period of time after the start of the verification step. If it is found that the starting device 2 is engaged, a first operation 48 is generated so as to stop the preheating process. If, on the contrary, it is detected that the starting device is not engaged, a second operation 50 is generated so as to control the priming of the post-treatment device, by measuring the temperature of the post-treatment device.

[0072] When a first result 54 indicates that the post-treatment device 100 has not reached its initiation temperature, the heating power level remains at its maximum, and the second operation is performed in a loop until the initiation temperature is reached. Alternatively, when a second result 56 indicates that the post-treatment device 100 has reached its initiation temperature, the heating power level is reduced to a lower level, which may be the threshold heating power level 22 or an intermediate heating power level 44. The reduction to such a lower heating power level makes it possible to maintain the thermal inertia in the post-treatment device 100 while reducing the electrical consumption of the thermal system 101.

[0073] It should be noted that if the verification step 46 has only been illustrated in the second embodiment, it can also be implemented, without departing from the context of the invention, in the first embodiment of the preheating method.

[0074] Figure 5 illustrates the evolution of the percentage of the heating level of the thermal system during the preheating process, here expressed as a percentage of the maximum heating level, with in particular a threshold heating level 22, an intermediate heating level 44 and a maximum heating level 26. Curve 60 is representative of the temperature of the post-treatment device 100 as a function of the time since the start of the preheating process and the heating power level.

[0075] As can be seen in Figure 5, the launch step 6 is such that the control unit 102 controls the thermal system 101 so that it operates at a first threshold heating level 22, here of the order of 30% of the maximum heating power of the thermal system, so that the temperature of the post-treatment device 100 increases gradually over time, according to a first notable increase 62 on the curve 60 which brings the system to a first temperature level. When a key action representative of a desire to start is detected during the intermediate detection step 8 of the intermediate cycle 42, the intermediate increase step 10 triggers the increase in the heating power level to an intermediate threshold heating power level 44, here 70%. The first intermediate cycle 42 is then completed.This increase in power results in a more rapid increase in the temperature of the post-treatment device 100, this increase 64 being noticeable on the curve 60 of figure 5. The final cycle 40 closes this preheating process 4 by increasing the heating power level to its maximum heating power level 26, the final increase 30 in the temperature of the post-treatment device 100, visible on the curve 60 of figure 5, then being the fastest possible.

[0076] The preheating method may comprise a plurality of intermediate cycles 42 between the launch step 6 and the final cycle 40. The second embodiment is not limiting of the number of possible intermediate cycles 42, the number of intermediate cycles 42 between the launch step 6 and the final cycle 40 being a function of the representative key actions detected and reported to the control unit.

[0077] The power levels allocated to the thermal system 101 during the different stages, which are a function of the type of key action AC representing a desire to start, may vary according to a learning process carried out by the control unit. In other words, a recording of the last cycles implemented during the previous preheating operations and the resulting energy expenditure is provided, in order to optimize the energy expenditure for the following preheating operations and in particular the different heating thresholds to be associated with the detection of the key actions AC.

[0078] We will now describe an example of embodiment of a detection means, with reference to figures 6 and 7, it being understood that this example implementing at least one heterodyne sensor is to be considered as a non-limiting example of the invention.

[0079] The at least one heterodyne sensor comprises a pair of oscillators, with a variable frequency oscillator having an antenna and a fixed frequency oscillator having no antenna. The frequency of the variable frequency oscillator is capable of being modified in response to the passage of the user's hand within the detection field of the antenna of the variable frequency oscillator.

[0080] When nothing interferes in the detection field of the antenna, the frequency of the variable frequency oscillator remains the same, that is to say substantially equal to the frequency of the fixed frequency oscillator. When a body, and in particular the user's hand, enters the detection field of the antenna, the body modifies the frequency of the variable frequency oscillator. The frequencies of each oscillator are processed in a dedicated calculator and the output signal calculated there varies according to the frequencies of each oscillator, and in particular according to the variation of the frequency of the variable frequency oscillator. The analysis of the output signal makes it possible to know the distance between the body and the sensor and this provides a sphere of possible positions of this body in relation to the heterodyne sensor.

[0081] Figure 6 shows an embodiment in which a single heterodyne sensor 66 is used. In this embodiment, the heterodyne sensor 66 is located near the starting device 2. When the driver's hand is located in the detection zone 68 of the sensor 66, the heterodyne sensor 66 is therefore able to know the distance between the hand and the starting device.This results in information on a position of the user's hand relative to the button of the starting device, and the control unit can process this raw material information, in particular by triggering an action on the thermal system when the distance between the hand and the starting device is of a value lower than a threshold distance, or in a more analytical manner by taking into account the evolution of this distance value between the user's hand and the starting device, in particular by triggering an action on the thermal system when the distance, below a certain threshold, tends to decrease.

[0082] Figure 7 shows an alternative embodiment, in which three heterodyne sensors 70 are used, being distributed around the starting device 2. For example, a first heterodyne sensor is arranged substantially in the area of ​​the steering wheel, a second heterodyne sensor and a third heterodyne sensor are arranged at a distance from each other on the dashboard. Each heterodyne sensor operates as previously mentioned and sends information back to the control unit when the hand is detected, that is to say when it is in the detection zone 68 around the heterodyne sensor. The use of 3 heterodyne sensors 70 makes it possible to triangulate the position of the hand and therefore to obtain precise information without needing to locate the sensor on the start button as previously mentioned.The invention, as just described, achieves the goal it set itself, and makes it possible to propose a preheating method by successive temperature steps of a post-treatment device. The heating power level evolves throughout the method, following a launch step and as and when a key action representative of a desire to start the vehicle is detected. Thus, according to the invention, the preheating method is particularly attractive in that it makes it possible to avoid wasting electrical energy from the battery during false starts, and in that it allows on a larger scale the reduction of CO2 production by reducing the drag of the alternator which is used to recharge the battery once the vehicle has started.The preheating method is also attractive in that it takes into account the thermodynamics in the materials of the post-treatment device, as heating the post-treatment device too quickly and repeatedly can be bad for the materials included in the post-treatment device. Variants not described here could be implemented without departing from the context of the invention, provided that, in accordance with the invention, they implement a preheating method according to the invention with steps of increasing the heating level in successive stages.

Claims

CLAIMS 1. Preheating method intended to control the temperature rise of a post-treatment device (100) of a vehicle powered at least in part by an internal combustion engine, characterized in that the preheating method comprises a step of launching (6) preheating the post-treatment device (IOO) to a threshold heating power level (22, 44), and at least one cycle (40, 42) following the launching step (6), this cycle (40, 42) comprising a step of detecting (7, 8) a user action included in a list of key actions representative of a desire to start (103) the vehicle and a step of increasing (9, 10) the heating power level to a higher heating power level when a key action representative of a desire to start (103) the vehicle is detected.

2. Preheating method according to the preceding claim, during which the at least one cycle is a final cycle (40) with a final detection step (7) and a final increase step (9) at the end of which the heating power level is equal to a maximum heating power level (26).

3. Preheating method according to the preceding claim, during which a plurality of successive cycles are implemented after the launch step, with at least one intermediate cycle (42) taking place between the launch step (6) and the final cycle (40), the intermediate cycle (42) comprising an intermediate detection step (8) and an intermediate increase step (10) making it possible to change the heating power level from the threshold heating power level to an intermediate heating power level (22, 44).

4. Preheating method according to the preceding claim, in which a key action representative of a desire to start (103) the vehicle which can be detected in an intermediate cycle (42) consists of an action relating to the positioning of the user in contact with or within the vehicle.

5. Preheating method according to one of claims 2 to 4, in which the key action representative of a desire to start (103) the vehicle which can be detected in the final cycle (40) consists of the position of the hand in the area of ​​a vehicle starting device (2).

6. Preheating method according to one of the preceding claims, in which a verification step (46) is configured to detect the effective start of the vehicle, for a predetermined period of time and starting when the maximum heating power level (26) is reached.

7. Preheating method according to the preceding claim, in which the verification step (46) comprises detecting the temperature (52) of the post-treatment device in the case where the effective start-up is not detected.

8. Preheating system configured to implement a preheating method according to one of the preceding claims, intended to control the rise in temperature of a post-treatment device (100) of a vehicle powered at least in part by an internal combustion engine, the preheating system comprising at least one thermal system (101) configured to increase the temperature of the post-treatment device (100), a detection means (104) configured to detect a desire to start the vehicle, a control unit (102) configured to control an increase in the heating power level of the thermal system (101) as a function of the detection of said key action.

9. Preheating system according to the preceding claim, in which the detection means (104) comprises at least one heterodyne sensor (66) configured to detect a presence in an area close to a starting device, by voltage difference across the terminals of the sensor.

10. Preheating system according to the preceding claim, in which three heterodyne sensors (70) are positioned at a distance from each other around the area of ​​the starting device (2).

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