FR2979604A1 - Arbitration method for starting diesel engine for propulsion or traction of hybrid vehicle e.g. serial hybrid vehicle, involves sending instruction sent to starting device for starting of engine at end of countdown - Google Patents

Abstract

The method (2) involves considering a starting request (20) comprising desired maximum time (24) of provision of weakest engine torque and time (34) required for driving to start up of an engine given by a starting device (10). Current starting criticality time is modified. The remaining time (28) of advised fast pre-heating is considered before driving the engine by function of piloting steering candles (6). The possible time of pre-heating is indicated by a countdown. An instruction is sent to the starting device for starting the engine at end of the countdown. An independent claim is also included for a hybrid vehicle.

Description

The present invention relates to a start-up arbitration strategy for a diesel type engine used for a hybrid vehicle, as well as a hybrid vehicle implementing such a strategy. BACKGROUND OF THE INVENTION Some hybrid vehicles include a diesel engine and an electric machine that can be used for the traction of the vehicle, with a mounting of these hybrid series or hybrid type engines.

The vehicle comprises batteries storing electrical energy, which give a certain autonomy to achieve an electric ride without emission of polluting gas, also called "ZEV" mode. Depending on the charging capacity of the batteries, and depending on the possibility of recharging these batteries on an external power supply network, for example with a rechargeable vehicle on a "plug-in" type socket, it is possible to obtain the possibility of driving relatively long time without starting the diesel engine. We seek to achieve today on the electric mode courses of the order of 30 or 50km, which is interesting for urban driving in particular.

An engine management calculator manages the operation of each engine to meet the demands of the driver, and to optimize energy consumption and the emission of gaseous pollutants. For this type of hybrid vehicle it must be possible to start the diesel engine at any time, in a manner planned in advance or unexpectedly, to meet different needs such as extending the range of the vehicle once the electric batteries discharged , the initiation of comfort functions such as heating, or the delivery of a high torque following the request of the driver, for example to accelerate the vehicle in the case of an overtaking maneuver.

A problem that arises then is that the diesel engine cools during these periods of inactivity, while it must have a combustion chamber temperature high enough to allow a sufficiently fast start depending on the conditions posed by the start requests. Heating the combustion chambers is by glow plugs powered by an electric current, which may include different technologies. A so-called "ceramic" technology allows a prolonged maintenance in temperature without premature wear of these candles, but it involves a high cost. A so-called "metal" technology has a low cost, but the candles wear out quickly in case of prolonged temperature maintenance. To anticipate starting of the diesel engine, a known strategy for preparing certain functions of this engine to start it, presented in particular by the document FR-A1-2931119, makes a determination of the torque demand to the wheels coming from the driver, and a determination of thresholds representing the energy optimization as well as the capacity to deliver the torque requested by the engines, to anticipate these starts.

It is thus possible to provide diesel engine start-ups, and to perform on-demand actions such as preheating the spark plugs to prepare these starts. However, this strategy does not take into account certain specificities relating to the time required to start a diesel engine, depending on the preheating time of the combustion chambers, or the actuation time of the engine drive device ensuring its start. , as a starter or an alternator, to arbitrate the start-up tradeoffs between the quality and urgency of this startup. The present invention is intended to avoid these disadvantages of the prior art.

To this end, it proposes a start-up arbitrage strategy for a diesel engine used for the traction or propulsion of a hybrid vehicle, taking into account various information on the state of the vehicle, as well as the maximum time required for at the disposal of the engine torque requested by one or more functions that issue engine start requests, to arbitrate the start time of this engine, characterized in that it performs the following steps when at least a first request is submitted to it: it takes into account the start-up request comprising the maximum desired time for providing the lowest engine torque, as well as the drive time required for starting the engine given by the starting device, to modify a common start-up criticality established by the arbitrage strategy, which goes from an arbitrary high value in the absence of a query, to a higher value s low dependent on this desired maximum time; - from the new start-up criticality, it delivers a candle piloting function, a candle preparation request with an adjusted dynamic; - It takes into account a remaining time of rapid warm-up recommended before driving the engine, given in return by the candle piloting function, and a countdown indicating the possible preheating time remaining; and - it sends to the starting member a starting instruction of the engine at the end of this countdown.

An advantage of the start-up arbitration strategy according to the invention is that it makes it possible to constantly monitor the start-up requests, to follow their evolutions and to respond as best as possible, in order to ensure comfort as well as security. The arbitration strategy according to the invention may further include one or more of the following features, which may be combined with each other.

Advantageously, in the event of a start-up request comprising a maximum desired time of provision of the engine torque, which is less than a preheating time recommended for rapid start-up of the engine without misfiring this engine, it may decide a early engine start before this time is advised. In particular, the arbitration strategy can decide an early start of the engine when the recommended rapid warm-up time remaining is greater than a value of about 2s. Advantageously, the arbitration strategy updates the current start-up criticality time to a lower value, if a change in the maximum desired times for provisioning the motor torque of the current startup requests leads to a new value of current critical start time which is lower than the current countdown of the remaining warm-up time.

Advantageously, the arbitration strategy updates the current start-up criticality time to a lower value, if a change in the drive time required for startup, leads to a new value of the current start-up criticality time which is lower than the countdown current of the preheating time remaining.

Updating the current critical start time can then cause the current countdown to be reset from this new current criticality time value. Advantageously, the arbitrage strategy defines requests for the preparation of the candles, with an adjusted dynamic for candles comprising a technology of the "metallic" type. The invention also relates to a hybrid vehicle comprising a diesel engine equipped with glow plugs, an auxiliary engine, and a computer supervising the operation of these engines, which implements a startup arbitration strategy comprising the any of the preceding features.

The invention will be better understood and other features and advantages will appear more clearly on reading the following description given by way of example and in a nonlimiting manner, with reference to the appended drawing of FIG. functional of the environment of the arbitration strategy according to the invention. FIG. 1 shows, for a hybrid vehicle comprising a diesel engine and an electric motor, a set of functions related to a startup preparation strategy comprising the arbitration strategy 2, comprising start request functions "i", a control function of the glow plugs 6 of the diesel engine, a fuel injection control function 8 in this engine, and a control function of the engine starting members 10, which can comprise two bodies such as a starter and an alternator -starter. Note that the start requests 4 issued by the functions "i" may be restart requests coming after previous start requests already issued by these same functions, which were followed by engine stops. The different functions communicate with the start-up arbitrage strategy 2 through information exchanges that can go both ways. The arbitrage strategy 2 is advantageously implemented by the computer that supervises and coordinates the operation of the two engines of the hybrid vehicle. The "i" start request 4 functions are functions that can intervene according to the state of their system, in order to request engine starts to deliver a torque that can be used for the traction of the vehicle, to drive accessories like the air conditioning compressor, or for other requirements such as the production of calories delivered to the heating system of the cabin. Each "i" function sends to the arbitration strategy 2, a restart request level "Ri_redem_MTH" which is 0 in the absence of a request, and 1 in the case of a request. The "i" functions can also be processed by an anticipation strategy 12 such as that presented in particular by the document FR-A1-2931119, to anticipate a need for restarting the engine, and send to the arbitrage strategy 2 a level restart anticipation request 22 "Ri_redem_MTH_ant" which is 0 in the absence of anticipation, and 1 in the case of anticipation. The functions "i" are further processed 14 to determine the criticality of their restart request, and send the arbitration strategy 2 a desired maximum time 24 for providing the engine torque "Ti_max_MTH_tournant". The following values are obtained for a first group of cabin comfort functions such as heating, air conditioning or demisting of the windows, which can issue queries for restarting the engine in an unpredictable manner, but whose requests are not urgent because the effects are noticeable. make it feel slowly: - "Ri_redem_MTH" = 1, when the function is activated by the driver, or according to the evolution of quantities specific to this function, - "Ri_redem_MTH_ant" = NA, no possibility of anticipation; - "Ti_max_MTH_tournant" = 3s, which is a long time given by way of example. The following values are obtained for a second group of functions dependent on variables operating with slow dynamics such as the temperature of the air or engine coolant, or the charge of the battery of the electric traction machine, which can issue requests to restart the engine in a predictable manner, and whose requests are not urgent because unsafe: - "Ri_redem_MTH" = 1, when exceeding a threshold; - "Ri_redem_MTH_ant" = 1, when a threshold is exceeded in anticipation of another threshold; - "Ti_max_MTH_tournant" = 2.5s, which is an average time given as an example.

The following values are obtained for a third group of functions dependent on variables operating with fast dynamics, such as the torque setpoint to the wheels depending on the will of the driver, whose predictability is highly variable but can be improved thanks to the strategy of anticipation 12: - "Ri_redem_MTH" = 1, when exceeding a threshold; - "Ri_redem_MTH_ant" = 1, when a threshold is exceeded in anticipation of another threshold; - "Ti_max_MTH_tournant" = 2s, which is a short time given by way of example.

In this example, the maximum desired time 24 for providing the engine torque "Ti_max_MTH_tournant" is limited to three different predefined values for all the functions. Alternatively the number of values may be larger, each function may even have its own values.

Moreover, the control function of the glow plugs 6 periodically calculates the need for preheating of the engine to start it, which is a function in particular of the temperature of the cooling fluid, the air temperature and the atmospheric pressure. The glow plug control function 6 indicates to the referee strategy 2 a recommended fast warm-up time remaining 28 before driving the engine "Tatt_dem_MTH", to obtain a quality start without a failure in the ignition of the injected fuel. . For example, an immediate start of the engine with a recommended warm-up time 28 of Os is excellent, with a time between 0 and 0.5s is correct, between 0.5 and 1 s is acceptable, between 1 and 2s is bad with risks of failures, and with a time superior to 2s is very bad with risks of not starting. Before starting the engine, the refereeing strategy 2 will ask the glow plug control function 6 a preparation of 5 candles 26 "Dde_prep_MTH", with a dynamic that depends on the urgency of the planned start. The dynamics of preparation is characterized by the heating power of the candles, given by the supply voltage of these candles. Note that a high power delivered to the candles reduces the preheating time, but causes greater wear of these candles. By way of example, the candle preparation request 26 "Dde_prep_MTH" can comprise a level 0 if there is no request for preparation, a level 1 for a low priority request, a level 2 for an average demand. priority, and a level 3 for a high priority request. In return for the candle preparation request 26 "Dde_prep_MTH" by the refereeing strategy 2, the piloting function of the glow plugs 6 begins a countdown or "time out" indicating the remaining warm-up time. The fuel injection control function 8 calculates the quantities of fuel to be injected for each combustion during starting of the engine, as a function of other parameters, in particular of the choice of the starting member that will be used in the case. where there are two, including a conventional starter and an alternator-starter. The choice of the starting device is given directly by the piloting function of the starting device 10. The fuel injection control function 8 receives from the arbitration strategy 2 a starting instruction 30 Dde_dem_MTH ", to make the necessary injections during this start. The driving function of the starting device 10 estimates permanently for each of the starting members, the drive time required for starting the motor 34 "Tent_dem_MTH", and transmits this time to the arbitration strategy 2. The drive time for starting the motor 34 "Tent_dem_MTH", depends on the different levels of torque that can deliver the selected starting member, according to its speed of rotation, which are related in particular to the state of this body as its temperature, or other components such as the voltage of the batteries that power it. The drive time also depends on the resistive torque of the motor that is related to many parameters such as the temperature of the coolant, oil or air. In return, the control function of the starting member 10 receives the starting instruction of the motor 30 "Dde_dem_MTH". According to the various information received periodically, the arbitration strategy 2 will request a preparation of the candles 26 "Dde_prep_MTH" in a timely manner, making a compromise to limit as much as possible the times and the heating power to preserve the duration life of these candles, while ensuring the necessary starts with sufficient conditions of responsiveness and quality of these starts.

The request for the preparation of candles 26 "Dde_prep_MTH" is elaborated by the arbitrage strategy 2, starting from a current start-up criticality time "T_criticité_dem_MTH" that it defines internally. The current starting criticality time "T_criticité_dem_MTH" depends on the presence or absence of startup requests 20 25 "Ri_redem_MTH", which are each associated with their desired maximum time of provision of the motor torque 24 "Ti_max_MTH_tournant", and also depends the training time required to start the motor 34 "Tent_dem_MTH". Starting the engine is all the more urgent as the current critical start-up time "T_criticité_dem_MTH" is low, and even less urgent that this time is high. In the absence of a start request 20, "Ri_redem_MTH" = 0 regardless of the "i" functions of start request 4, and the current start criticality time "T_criticité_dem_MTH" is defined as a value arbitrary high, for example 3s. The arbitration strategy 2 then carries out, as a preventive measure, a low priority candle preparation request 26 "Dde_prep_MTH" with a low level 1 dynamic, ie as soon as a restart anticipation request 22 occurs with "Ri_redem_MTH_ant" = 1, or at regular intervals in the absence of a restart anticipation request 10 22 with any function "i", "Ri_redem_MTH_ant" = 0. The low priority candle preparation request 26 "Dde_prep_MTH" performed at regular intervals thus allows a moderate preheating of the spark plugs with a low power to reduce their wear, which permanently maintains a possibility of not too slow starting of the engine thanks to the thermal inertia at these candles. In the presence of start requests 20 for at least one function "i" we have "Ri_redem_MTH" = 1. The current critical start time "T_criticité_dem_MTH" is calculated for the most critical start request, including the maximum desired time 24 of 20 provision of the engine torque "Ti_max_MTH_tournant" which is the lowest, according to this desired maximum time 24 of provision of torque, and the drive time required for starting the engine 34 "Tent_dem_MTH" . The arbitration strategy 2 then carries out, as a curative, a request for the preparation of the candles 26 "Dde_prep_MTH", with a dynamic adjusted according to the current start-up criticality time "T_criticité_dem_MTH" for the "i" function at the origin of the request the most critical, and according to the remaining time of rapid warming advised 28 before driving the engine "Tatt_dem_MTH", he can comply or not.

This provides a preheating adapted to the minimum necessary, which solicits little candles in the case where the request having the maximum desired time 24 of provision of the engine torque "Ti_max_MTH_tournant" the weakest is not very urgent, and who the strongly demands in the case where the request having the maximum desired time 24 of provision of the engine torque "Ti_max_MTH_tournant" the lowest is urgent. If several start requests 20 appear simultaneously then the most critical start request, that is to say the one comprising the maximum desired time 24 for providing the lowest torque "Ti_max_MTH_tournant", is taken into account by the Arbitrage strategy 2 to establish the current startup criticality time "T_criticité_dem_MTH". This first current critical criticality time value "T_criticité_dem_MTH" is used to initialize the value of the activated countdown when there is a start request "Ri_redem_MTH". The current starting criticality time "T_criticité_dem_MTH" is then updated to a lower value only if an evolution of 20 start requests 20 associated with their time of provision of the engine torque "Ti_max_MTH_tournant" 24, or an evolution of drive time for starting the motor 34 "Tent_dem_MTH" given by the control function of the starting device 10, leads to a value of the current starting criticality time "T_criticité_dem_MTH" lower than the instantaneous value of the account countdown during activation. In this case of update, the countdown being activated is then reset to the new value of the current critical startup time "T_criticite_dem_Dem_MTH", and the dynamics of the request for preparation of candles 26 "Dde_prep_MTH" is set updated accordingly.

The start of the motor drive for its start will be effective as soon as the countdown is finished, or as soon as the remaining time of rapid warming advised 28 before the motor drive "Tatt_dem_MTH" is equal to zero, in order to arbitrate the compromise between the quality and safety of the engine start on the one hand, and the urgency of this start on the other. This arbitration is carried out each time that in the absence of start request "Ri_redem_MTH", one or more MTH startup requests appear.

It is thus possible by optimizing the starts of a diesel engine, use this type of engine which has a higher performance than gasoline engines while preserving the life of the glow plugs, which can allow the use of spark plugs technology "Metallic" including a reduced cost.

We can also ensure the compromise between the life of candles on the one hand, and the requirements of comfort and safety of driving on the other hand. The start-up arbitrage strategy can thus increase the duration of driving in electric mode, and make it possible to achieve journeys that can reach distances of thirty or fifty km, with low outside temperatures that can be between +5 and 5 ° C , while preserving the quality of starting according to the possibilities.

Claims (8)

CLAIMS1 - Starting arbitration strategy of a diesel engine used for the traction or propulsion of a hybrid vehicle, taking into account various information on the state of the vehicle, as well as the desired maximum time of provision of the couple motor (24) requested by one or more functions (4) which issue requests for starting the engine (20), to arbitrate the starting moment of this engine (30), characterized in that it performs the following steps as soon as at least a first request is submitted to it: it takes into account the start request (20) comprising the maximum desired time (24) for providing the lowest engine torque, as well as the training time; necessary for the starting (34) of the motor given by the starting member (10), to modify a current starting criticality established by the arbitration strategy (2), which goes from an arbitrary high value to the absen this request, at a lower value depending on this desired maximum time; - From the new critical start-up criticality, it delivers to a candle piloting function (6), a candle preparation request (26) with an adjusted dynamic; - It takes into account a recommended fast preheating time (28) before driving the engine, given in return by the spark plug control function (6), and a countdown indicating the remaining possible preheating time; and - it sends to the starting member (10) a starting instruction of the motor (30) at the end of this countdown. 2 - Arbitration strategy according to claim 1, characterized in that in the case of a start request (20) comprising a desired maximum time (24) for providing the engine torque, which is less than a preheating time remaining fast recommended (28) for starting the engine without misfiring this engine, it can decide an early start of the engine before the time remaining advised. 3 - arbitration strategy according to claim 2, characterized in that it can decide an early start of the engine when the recommended fast warm-up time remaining (28), is greater than a value of about 2s. 4 - arbitration strategy according to any one of the preceding claims, characterized in that it updates the current critical time of startup to a lower value, if a change in the maximum desired time of provision of the couple engine (24) current start requests (20), leads to a new value of the current start critical time that is lower than the current countdown of the remaining warm-up time. 5 - arbitration strategy according to any one of the preceding claims, characterized in that it updates the current critical start time to a lower value, if an evolution of the training time required for startup ( 34), leads to a new value of the current starting criticality time which is lower than the current countdown of the remaining warm-up time. 6 - arbitration strategy according to claim 4 or 5, characterized in that the update of the current start critical time, causes a reset of the current countdown from this new value of current critical time. 7 - Arbitration strategy according to any one of the preceding claims, characterized in that it defines requests for the preparation of candles (26), with a dynamic adjusted for candles comprising a technology of the "metallic" type. 8 - Hybrid vehicle comprising a diesel engine equipped with glow plugs, an auxiliary motor, and a computer supervising the operation of these engines, characterized in that the calculator implements a startup arbitration strategy (2) performed according to any one of the preceding claims.