FR2994920A1 - Method for optimizing electric rolling and starting of depollution system of e.g. petrol engine of hybrid vehicle, involves supporting rolling of system without requiring starting of engine if power is lesser than starting threshold - Google Patents

Abstract

The method involves implementing a driving strategy for providing a nominal optimized traction energy threshold. An electric machine i.e. traction motor (36), is maintained by the energy threshold if a driver requires a power lesser than the energy threshold. A depollution strategy is established to give a starting threshold of a depollution system, where the starting threshold is leveled with energy remaining in a battery (12). Rolling of the system is supported by the energy without requiring starting of an internal combustion engine (28) if the power is lesser than the starting threshold. An independent claim is also included for a hybrid vehicle.

Description

The present invention relates, for a hybrid vehicle, to a method for optimizing the running with an auxiliary energy, and to a method for optimizing the running with an auxiliary energy, and to provide a method for optimizing the running with an auxiliary energy. priming the pollution control system of a heat engine, and a hybrid vehicle implementing such a strategy.

Some hybrid vehicles comprise a combustion engine which may be of the gasoline or diesel type, associated with a second engine using an auxiliary energy source, operating without emission of polluting gases and which can be recharged during the running of this vehicle, to reduce energy consumption and emissions of gaseous pollutants.

The second motorization can be in particular an electric traction machine powered by batteries, which can be recharged only by the onboard electrical machine, or by an external electricity distribution network, after a connection on the network during a shutdown. of the vehicle.

The electric machine can operate as a traction motor of the vehicle, by taking electrical energy from the batteries, or by a generator, by recovering the kinetic energy of the vehicle to produce a charging current of these batteries. It is thus possible to achieve different modes of operation, including in particular an operation only with the heat engine, operation only with the second engine without emission of pollutant gas, or operation combining these two engines to deliver a higher power. The heat engines generally comprise different systems 30 for treating the exhaust gas emissions, which are in the exhaust line, in order to perform in particular a gas catalysis, a filtering of the emitted particles and a regeneration of the filter, or a reduction of nitrogen oxides. To be effective, these pollution control systems must operate under certain conditions, especially with relatively high temperatures.

A problem that arises for these hybrid vehicles is that depending on the conditions, with a traction of the vehicle by the second engine to optimize the fuel efficiency, the engine can remain stopped for periods of more or less significant duration. The exhaust line may not heat up enough when starting the vehicle, or cool down after warming up. Some types of hybrid vehicles include electric heating of the pollution control systems, but heating consumes a relatively large electrical power, which then decreases the range of the vehicle.

In general, for hybrid vehicles it is sought not to activate the engine during the starting of the vehicle, using the second engine during this start and for low speed runs, in order to optimize fuel consumption. energy. In this case, there is no priming of the pollution control system of the engine. This demand is even more important for a hybrid vehicle with rechargeable batteries on an electricity distribution network, this vehicle usually starting with full batteries. A known engine management method, presented in particular by document FR-A1-2808050, controls the starting of the engine according to the power demands presented by the driver, and the temperature of the pollution control system. In particular, when the temperature of the pollution control system is insufficient to ensure its activation, the power of the heat engine is limited to reduce emissions of gaseous pollutants.

A problem that arises is that it is necessary to manage the antagonistic electric driving needs after starting the vehicle, and priming the pollution control system of its engine. The present invention is intended to avoid these disadvantages of the prior art. To this end, it proposes a method of optimizing the energy consumption and the depollution of the heat engine, for a hybrid vehicle comprising a second engine powered by a renewable auxiliary energy reserve, and a traction engine comprising minus an exhaust gas depollution system requiring a warm-up to start its operation, this vehicle implementing a traction strategy giving a first nominal threshold of optimized traction energy, which maintains traction by the second engine if the driver requires a power lower than this threshold in order to optimize energy consumption, characterized in that it establishes a decontamination strategy giving a second threshold of priming of the pollution control system, defined with respect to this first nominal threshold of traction and the level of energy remaining in the auxiliary energy reserve, which e driving with this energy by not requiring starting of the engine for the need for ignition, if the traction strategy does not require it, or if the driver power demand is below this second threshold of ignition. An advantage of the method according to the invention, and that the implementation of the second strategy dependent on the first, makes it possible to limit the starting of the engine to the case of operation requiring at the same time a rather strong power, with reserves of energy in the batteries, which makes it possible to promote electric driving and the reduction of polluting gas emissions. The optimization method may further include one or more of the following features, which may be combined with each other.

Advantageously, the second threshold of priming of the pollution control system is equal to the first nominal threshold of optimized traction energy, so as not to anticipate start of the engine from a low demand of power of the driver.

Advantageously, to anticipate the start of the engine in order to control its emissions at startup, and reduce the need for load shedding of this engine, the second threshold of priming of the pollution control system is equal to the first nominal threshold of optimized traction energy, less a small difference may depend in particular on the speed of the vehicle, the level of charge of the auxiliary energy reserve, and the type of pollution control system used. The subject of the invention is also a hybrid vehicle comprising a traction engine comprising at least one exhaust gas depollution system requiring a warm-up to start its operation, and a second engine powered by an auxiliary energy reserve. renewable, this vehicle implementing a method of optimizing the running with the auxiliary energy and priming of the engine exhaust system, comprising any one of the preceding features.

In particular, the auxiliary energy may be electricity. The invention will be better understood and other features and advantages will emerge more clearly on reading the following description, given by way of example and in a nonlimiting manner with reference to the appended drawings, in which: FIG. a diagram presenting the main functions relating to engines, which are linked to the optimization strategy; FIG. 2 is a block diagram of the optimization method; FIGS. 3 and 4 are graphs showing the speed of the vehicle and the phases of optimal use of the engine, for a first and a second driving cycle; FIGS. 5 and 6 are graphs showing the speed of the vehicle and the behavior of the heat engine with a need for priming of the pollution control system, for the first and second rolling cycles; and FIG. 7 and a graph showing the speed of the vehicle and the strategy for unloading and maintaining the heat engine at a controllable speed for the second driving cycle. FIG. 1 shows, for the traction of a hybrid vehicle, a heat engine 28 comprising a pollution control system having to heat up in order to be effective, one or more electrical machines 36, an intelligent management function of the level of load shedding of the heat engine. 2, and an intelligent start management function of this heat engine 4. The two intelligent management functions 2, 4 implement the method of optimizing the electrical rolling and priming of the pollution control system according to the invention. . Advantageously, a control computer of all the engines of the hybrid vehicle, contains these different functions. The management of the level of load shedding of the heat engine 2 receives information from the pollution control system 6, sending data on its activation level 8 which is related in particular to its temperature. The starting management of the heat engine 4 also receives the same information from the pollutant gas treatment system 6, as well as information on the energy level 12 of the batteries 10 which supply the electric traction machine. The starting management of the heat engine 4 further receives a torque setpoint to the wheels 20 representing the demand of the driver 14, which it expresses by pressing on the accelerator pedal 16 in order to send a signal to a processing interface of the request 18, delivering this set torque.

An intelligent distribution function of the torque setpoint to the wheels 24, receives the torque setpoint to the wheels 20, a start-up decision of the engine 22 coming from the starting management of this engine 4, and a torque limit of the engine 26 from the management of the load shedding level of this motor 2. The intelligent distribution function of the torque setpoint 24 sends a heat engine torque setpoint 30 to this heat engine 28, as well as an electric machine torque set point 34 to this electric machine 36. The electric machine 36 gives a return on its operation 34, to the intelligent distribution function of the torque setpoint 24. The heat engine 28 further receives the torque limit of the heat engine 26 from the management of the level of shedding of the engine 2, and sends information on its operation 32 to the electric machine 36. The method of optimizing the electric rolling and the amor age of the pollution control system, makes it possible to ensure electric running when the vehicle is actuated without starting the heat engine 28. It also allows the engine to be started in order to prime the pollution control system 6 by raising it to temperature while respecting the levels of emission of gaseous pollutants by this engine after it has been started, by releasing it by the electric machine 36, and keeping it at a controllable speed which is the idle speed or a speed close to this idle speed, until the complete priming of the pollution control system.

At each identification of a priming need of the pollution control system, the optimization process achieves three objectives. The first objective is to ensure the electric taxiing to the activation of the vehicle, without starting the heat engine 28. The second objective is to meet the emission levels of gaseous pollutants when the heat engine 28 is requested and that its pollution control system 6 is not yet initiated, by offsetting this engine on operating points highly emissive pollutant gas, and delivering the complement of power required by the driver, by one or more electrical machines 36. The third objective is to initiate the pollution control system 6 after the first start of the heat engine 28 for a traction requirement, either by performing the traction with this engine while respecting the second objective, or by maintaining the engine idle. The optimization method according to the invention can be applied with other sources of auxiliary energy, such as for example compressed air, which can be generated during running of the vehicle by recovering a kinetic energy of this vehicle . The operation of the method of use refers to the diagram of FIG. 2, comprising a first block 40 relating to the stopping of the thermal engine as well as its starts at control speeds allowing the priming of the pollution control system, and a second block 80 concerning the running with this engine as well as its load shedding if necessary. This diagram shows the information on the energy level of the batteries 12, as well as on the wheel torque setpoint 20 established on the basis of the driver's request, which are delivered to the traction strategy 42 giving a first nominal threshold. optimized traction in energy, to evaluate these values with respect to this first threshold. The first nominal energy optimized traction threshold is based on the analysis of the yields of the various traction paths comprising the heat engine, and one or more electrical machines, to distribute the load of each of these engines. In the case where the torque demand is quite low compared to this first threshold, the traction strategy 42 selects an electrical rolling 44, and the method studies the need for activation of the pollution control system 46.

If the pollution control system 46 is in its optimal operating conditions, the method controls a shutdown of the heat engine 48, presented by the branch B. If there is a need for activation of this pollution control system, the method takes into account in addition, the energy level of the batteries 12, to evaluate these values with respect to a second threshold of priming of the pollution control system established by a pollution control strategy 50, which depends on this energy level in the batteries. In the case where the torque demand 20 is quite low compared to the second threshold of priming of the pollution control system, the decontamination strategy 50 controls a stopping of the heat engine 48. In the case where the torque demand 20 is strong enough. with respect to this second threshold, the decontamination strategy 50 requires a start of the engine 52 presented by the branch D, to maintain it at a controllable speed which is the idle speed or a regime close to this idle, in order to start the pollution control system. In the case where the torque demand 20 is relatively high compared to the first nominal value of optimized traction energy, the traction strategy 42 allows a start of the engine 54 to ensure traction of the vehicle. The method then studies the need for activation of the pollution control system 46. If the pollution control system 46 is in its optimum operating conditions depending on the first energy optimized traction nominal threshold, the method controls an authorization to stop the engine. thermal 56 presented by the branch A. Generally, in a first mode of operation, the activation of the vehicle or while driving, the pollutant treatment system 6 is in the optimal operating conditions, l Nominal energy optimization is applied. Decisions for starting or stopping the thermal engine for traction are performed in accordance with the demand of the conductor 20 and the energy level in the battery 12, which corresponds to the branches A and B of the diagram. . If there is a need for activation of the pollution control system 46 with respect to the first nominal threshold of optimized traction in energy, the method 5 commands a stopping prohibition of the heat engine 58 presented by the branch C, which allows a start the heat engine 52 to maintain it at a controllable rate. In the case of this need for activation of the pollution control system 46, the method also sends information 60 to the second block 80 relating to taxiing with traction of the vehicle by the engine, which completes information coming from the activation level. of the pollution control system 62, in order to establish information on the power limitation of the heat engine 64. Advantageously, the second priming threshold of the abatement system is defined relative to the first nominal threshold of optimized traction in energy, so as not to anticipate the start of the engine from a low demand of biasing power, which generally corresponds to an urban-type taxi. In this case, the second threshold of priming of the pollution control system is equal to the first nominal threshold of optimized traction in energy. The second boot threshold is also defined relative to the first nominal threshold, so as to anticipate the start of the engine to control its emissions at startup, and reduce the need for load shedding of this engine. The second threshold of priming of the pollution control system is then equal to the first nominal threshold of optimized traction in energy, minus a small deviation or delta being able to depend in particular on the vehicle speed, the level of charge of the batteries, and the type of system of depollution used. Furthermore, the information on the power limitation of the heat engine 64 is added to the torque setpoint to the wheels 20, to study the capability of the engine 66 to deliver the torque according to this request of the driver.

If the capability of the heat engine to deliver torque 66 under acceptable pollution conditions is established, then the method controls rolling only with this engine 68. If its capability to deliver torque 66 under acceptable pollution conditions is not established, then the process requires a portion of the traction power to the electric machine 70, so as to limit the power delivered by the engine to maintain its operation in ranges where its level of pollution is acceptable. Figures 3 to 7 show, as a function of time t, the speed of the vehicle 90, and the starting of the engine 92, 100, 102, 110, 120, 122, indicating the speed of rotation of this engine. For a vehicle that does not have a need for priming the pollution control system, FIG. 3 shows a rolling cycle with an energy level in the batteries below a threshold. We then have frequent starts of the engine 92, as soon as the speed of the vehicle increases sharply. For the same lack of priming of the pollution control system, Figure 4 shows a rolling cycle with an energy level in the batteries above this threshold. There are then very few starts of the heat engine 92, which take place at points of strong power demand by the driver, corresponding to significant accelerations giving high speeds of the vehicle. For a vehicle having a priming requirement of the pollution control system, and for the same cycle as that shown in FIG. 3, it can be seen from FIG. 5 at the beginning of this cycle after a first start 100 of the heat engine on the request of the traction strategy , a prohibition of stopping the engine 102 and a maintenance running at a controllable regime as the pollution control system is not in the optimal operating conditions, in order to meet the need for the clean-up strategy. This operating mode corresponds to branch C of the diagram of the optimization method presented in FIG. 2. The following starts 92 no longer include the prohibition of stopping the engine, the depollution system being in temperature. For the same need for priming the pollution control system, and for the same cycle as that shown in FIG. 4, FIG. 6 shows during this cycle a start 110 of the heat engine on the demand of the depollution strategy, and a maintaining a controllable regime as the decontamination system is not in the optimal operating conditions, corresponding to the branch D of the scheme of the optimization process shown in FIG. 2. For the controllable regime corresponding to the branches C and D of FIG. diagram, the engine is maintained started with a control of the speed and the load. The traction chain of this engine, including the state of the gearbox comprising the selected gear, and the clutch, is controlled to adjust its rotational speed and minimize the losses of this engine. FIG. 7 shows, for the same cycle as that presented in FIGS. 4 and 6, a traction of the vehicle by the heat engine, which is only performed for a requirement defined by the energy optimization conditions given by the traction strategy 42, and a need for activation 20 of the pollution control system 46. If the energy in the battery 12 is greater than an energy threshold, and the pollution control system 46 out of its optimal conditions, the energy optimization strategy may require a start of the engine on points of high stress, which are potentially highly emissive. In order to obtain the most homogeneous vehicle behaviors possible whatever the state of the pollution control system, the difference between the first energy optimized traction threshold and the second pollution control system start threshold may be small, and reach a zero value. In this case, the holding time of the heat engine at a controlled rate with a controlled load, presented by the branch D of the diagram, may not be sufficient to bring the pollutant treatment system to its optimum conditions. The optimization process then limits by the intelligent management function of the load shedding level of the heat engine 2, the power of the engine to give an acceptable level of emission of gaseous pollutants, by performing load shedding that transfers through the distribution function intelligent intelligent torque setpoint 24, the power demand remaining to be provided to the electric machine 36 This limitation of power delivered by the heat engine evolves proportionally to physical criteria characteristic of the level of priming of the pollution control system, in particular its temperature . The load shedding is active as long as the pollution control system is not in its optimal conditions. Maintaining the operation of the engine is done by controlling the speed and load of this engine.

In FIG. 7, there is successively a starting of the heat engine with a control at a controllable speed 120 to limit the emissions of gaseous pollutants, a complementary part of the traction power being demanded from the electric machine 70. normal of the engine 122 which drives the vehicle, the pollution control system being activated.

Claims (5)

CLAIMS1 - Method for optimizing electric rolling and priming of the pollution control system of a heat engine, for a hybrid vehicle comprising a second motor (36) powered by a renewable auxiliary energy reserve (10), and an engine thermal traction (28) comprising at least one exhaust gas depollution system requiring a warm-up to start its operation, the vehicle implementing a traction strategy giving a first nominal threshold of optimized energy traction, which maintains a traction by the second motor (36) if the driver requests a power below this threshold in order to optimize the power consumption, characterized in that it establishes a decontamination strategy giving a second threshold of initiation of the system of decontamination, defined with respect to this first nominal traction threshold and the energy level remaining in the energy reserve e auxiliary (12), which promotes the running with this energy by not requiring starting of the engine for the need of priming, if the traction strategy does not require it, or if the demand for power of the driver is less than this second boot threshold. 2 - optimization method according to claim 1, characterized in that the second priming threshold of the pollution control system is equal to the first nominal threshold of optimized traction energy, so as not to anticipate starting the engine from a low demand for driver power (20). 3 - optimization method according to claim 1 or 2, characterized in that to anticipate the start of the engine to control its emissions at startup, and reduce the need for load shedding of the engine, the second system boot threshold The decontamination threshold is equal to the first energy optimized traction threshold, minus a small difference that may depend in particular on the speed of the vehicle, the level of charge of the auxiliary energy reserve, and the type of pollution control system used. 4 - Hybrid vehicle comprising a traction engine (28) comprising at least one exhaust gas depollution system requiring a warm-up to start its operation, and a second motor (36) powered by an auxiliary energy reserve renewable (10), characterized in that it implements a method of optimizing the running with the auxiliary energy and priming of the pollution control system of the engine, carried out according to any one of the preceding claims. 5 - hybrid vehicle according to claim 4, characterized in that the auxiliary energy is electricity.