TECHNICAL FIELD OF THE INVENTION

This invention concerns a method for controlling operation of a hybrid automotive vehicle equipped with an internal combustion engine, an electric machine and an electronic control unit, each of the internal combustion engine and the electric machine being adapted to deliver torque to a driveline of the vehicle. The invention also concerns a hybrid automotive vehicle adapted to perform such a method.

BACKGROUND OF THE INVENTION

On hybrid vehicles, electrically powered auxiliary equipments are fed by an electric machine or by a battery set. If several auxiliary equipments are activated at the same time, the electrical needs of those equipments can reach a peak, in terms of instant power, or in terms of energy, or both. If the peak of electrical need is high in a period when the internal combustion engine is shut down, a restart of this engine may be needed in order to generate enough extra electrical energy to operate the auxiliary equipments. A restart of the internal combustion engine provokes fuel over-consumption.

For instance, the simultaneous use of electrically driven power take-off and air conditioning systems can provoke a peak of electrical need and, as a consequence, a restart of the internal combustion engine.

To avoid restart of the internal combustion engine, it is possible to control the operation of the electrically fed auxiliary equipments in order to avoid peaks of electrical need, as explained in WO-A-2008/050617. In this case, each auxiliary equipment estimates its future electrical consumption, and the electronic control unit is adapted to allocate available power between the equipments when a lack of power is forecast. This solution does not allow the operation of all the auxiliary equipments at a time in all circumstances, because it only manages priority between the equipments.

Another solution, explained in US-B-7 503 413, determines when to allow the internal combustion engine to be placed in an engine standby mode. If an electrical power need is forecast, the engine is not allowed to standby in order to be able to generate electrical power at the time of the need. The main drawback of the technique is that it only avoids stopping the engine for restarting it immediately thereafter.

Neither of these two techniques is able to adapt the electrical energy production on the basis of an estimate of future electrical energy needs. SUMMARY OF THE INVENTION

This invention aims at proposing a new method for controlling operation of a hybrid automotive vehicle which forecasts the upcoming operations of electrically fed auxiliary equipments, estimates future electrical energy needs and, if a shortage of electrical energy is forecast, generates extra electrical energy.

To this end, the invention concerns a method for controlling operation of a hybrid automotive vehicle, equipped with an internal combustion engine, an electric machine, an electronic control unit and at least one electrically powered auxiliary equipment, each of the internal combustion engine and the electric machine being adapted to deliver torque to a driveline of the vehicle. This method is characterized in that it comprises at least the following steps:

a) forecast of the upcoming operations of electrically fed auxiliary equipments of the vehicle ;

b) estimation of future electrical energy needs for the auxiliary equipments to execute the upcoming operations forecast at step a);

c) comparison between the energy needs estimated at step b) and the actual status of electrical energy production of the vehicle, its electrical energy consumption and the state of reserve of electrical energy on-board the vehicle;

d) forecast of a possible electrical energy shortage on the basis of the comparison made at step c);

e) if a shortage of electrical energy is forecast at step d), generation of extra torque by the internal combustion engine.

Thanks to the invention, electrical energy need peaks are anticipated, extra electrical energy is generated by the internal combustion engine, and electrical energy is used for the right use, at the right time and at the lowest cost. Inappropriate engine restarts or shutdowns are avoided, all the operations of the auxiliary equipments are executed and fuel is saved.

According to further aspects of the invention which are advantageous but not compulsory, such a method might incorporate one or several of the following features:

- The totality of the extra torque generated at step e) is delivered to the driveline of the vehicle and energy taken from a battery set connected to said electric machine is decreased.

- It comprises a further step f) of conversion of at least a part of the extra torque generated by the internal combustion engine at step e) into energy and storage of said energy. - At step f), energy is converted into electrical energy and stored in a battery set connected to the electric machine.

- At step f), energy is converted into pneumatic energy and stored in a tank.

- The vehicle is equipped with an automatic gearbox and at step e), the ratio of the automatic gearbox is selected on the basis of the extra torque to be generated by the internal combustion engine.

- If a shortage of electrical energy is forecast at step d), the operation conditions of the internal combustion engine are set for a predetermined period of time for what concerns at least its regime and its operation period(s).

- In step e), extra torque is generated by increasing the ratio of the torque delivered by the internal combustion engine with respect to the global torque delivered by the internal combustion engine and the electric machine to the driveline, as compared to a situation where no shortage of electrical energy is forecast at step d).

- At least a part of the extra torque generated at step e) is delivered to the driveline of the vehicle.

The method may further comprises the steps of:

a') forecast (101) of the upcoming path to be followed by the vehicle (1);

b') estimation (102) of future electrical energy needs, positive or negative, for the electric machine to deliver torque to the driveline along the path forecast at step a); so that, at step c), the energy needs estimated at step b') are added to the energy needs estimated at step b).

The invention also concerns a hybrid automotive vehicle with which the above- mentioned method can be implemented. More precisely, the invention concerns a hybrid automotive vehicle equipped with an internal combustion engine, an electric machine, an electronic control unit and at least one electrically powered auxiliary equipment, each of said internal combustion engine and said electric machine being adapted to deliver torque to a driveline of the vehicle. This vehicle is characterized in that it comprises means to forecast upcoming operations of the electrically fed auxiliary equipments on the basis of a predetermined route to be followed by the vehicle, means to estimate the electrical energy needs for the auxiliary equipments to execute the operations, means to compare the electrical energy needs to the actual status of electrical energy production of the vehicle, its electrical energy consumption and the state of reserve of electrical energy on-board the vehicle, means to forecast a possible electrical energy shortage and means to control the internal combustion engine so as to generate extra torque if an electrical energy shortage is forecast. According to further aspects of the invention which are advantageous but not compulsory, such a vehicle might incorporate one or several of the following features:

- It comprises means to convert at least a part of the extra torque into energy and to store said energy.

- An electronic control unit includes at least the means to estimate the electrical needs for the auxiliary equipment to execute the operations, the means to compare the electrical energy needs to the actual status of electrical energy production of the vehicle, its electrical energy consumption and the state of reserve of electrical energy on-board the vehicle, the means to forecast a possible electrical energy shortage, and the means to control the internal combustion engine.

- The electronic control unit is adapted to control the ratio of the torque delivered by the internal combustion engine with respect to the global torque delivered by the internal combustion engine and the electric machine to the driveline.

- The electronic control unit is adapted to control an automatic gearbox connected to the driveline of the vehicle.

- The electronic control unit is adapted to set the operation conditions of the internal combustion engine.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will now be explained in correspondence with the annexed figures and as an illustrative example, without restricting the object of the invention. In the annexed figures:

figure 1 is a schematic representation of a truck embodying the invention;

- figure 2 is a block diagram representing a method according to the invention.

DETAILED DESCRIPTION OF SOME EMBODIMENTS

As illustrated on figure 1 , a hybrid vehicle 1 comprises an internal combustion engine 10 connected to a gearbox 12, which can be automatic or automated manual. The vehicle 1 also comprises an electric machine 20 fed by a battery set 22. Each of the internal combustion engine 10 and the electric machine 20 are adapted to deliver torque to a driveline 30 of the vehicle 1. The internal combustion engine 10 is also adapted to deliver torque to the electric machine 20 in order for it to generate electrical energy.

A sensor 42 monitors the state of charge of the battery set 22 and is adapted to deliver, in the form of an electric signal S ₄₂ , information about the state of charge of battery set 22 to an electronic control unit 40. The internal combustion engine 10 may also be adapted to deliver torque to a compressor 28, in order to pressurize a quantity of air which can be stored in a tank 24. The hybrid vehicle 1 may be provided with pneumatically powered auxiliary equipment 54, such as a braking system, fed by the pneumatic energy tank 24. The compressor, rather than being directly mechanically driven by the engine, can be driven by an electrical motor deriving its electrical energy, directly or indirectly from the battery set 22.

A pressure sensor 44 monitors the pressure in the tank 24 and is adapted to send, in the form of an electric signal S ₄₄ , the value of the air pressure in the tank 24 to the electronic control unit 40.

The hybrid vehicle 1 is provided with an electrically powered auxiliary equipment 50, such as a garbage compactor, which is driven by an electrical machine 51 , deriving its electrical energy, directly or indirectly from the battery set 22.

The hybrid vehicle 1 may include several other electrically powered auxiliary equipments, such as lights, a power steering or a cooling system, which are not represented on the figures. Such systems can also include an electric tailgate, an electric heater, a refrigeration unit for controlled temperature transport, a tipper, a crane, cherry picker, concrete mixer... , or any application that may use a vehicle power take-off and that can be electrically powered on a hybrid vehicle. It must be noted that such equipment can be in fact hydraulically driven, but the hydraulic circuit may itself be pressurized by an electrically driven pump.

The hybrid vehicle 1 comprises an electronic control unit 40 which communicates with the internal combustion engine 10, the electric machine 20, and controls the gearbox 12 via respective electronic signals Si ₀ , S ₂₀ and S ₂ . The electronic control unit 40 is represented here as unitary, but it could be in the form of several electronic control units connected, for example, by a databus of an electronic control network of the vehicle.

The hybrid vehicle 1 also comprises forecasting means 60 which are adapted to provide a forecast of upcoming expected use of electrically fed auxiliary equipments of the vehicle for an upcoming given period of time. The expected use may include information about upcoming events where it can be anticipated a certain use of at least one electricity consuming auxiliary equipment, such as a bus stop, a tunnel or the proximity of a place where the vehicle is expected to execute specific operations, such as loading or unloading with an electric tailgate. It may also include information about the theoretic order and duration of specific operations. For instance, a garbage truck may have to execute compactions every four times garbage is collected. Such information can be based on the comparison of an instant location of the vehicle, as provided for example, with a previously stored database of locations where certain auxiliary equipment operation is to happen. Such information can also be based on the detection of the occurrence of a certain number of vehicle operating parameter conditions, which may be associated with an upcoming operation of certain auxiliary equipment.

The forecasting means can also comprise a navigation device capable of determining a route which to be followed by the vehicle 1. The route gives information about the path of the vehicle for an upcoming given period of time. The path may include geographic information, such as slopes and curves of the road, as well as traffic related indications, such as an average speed on a path portion, compulsory stopping points, etc...

Therefore, the forecasting means 60 may forecast both the upcoming path and the expected use of the vehicle. The forecasting means can deliver, in the form of an electric signal S ₆ o, information concerning the expected use, and possibly also concerning the upcoming path, to the electronic control unit 40

On this purpose, forecasting means 60 may include a slope sensor or any equivalent means. Forecasting means 60 may also include a satellite navigation system, for example based on GPS, in order to localize curves, bus stops, tunnels, places of delivery of goods, or any other place that may need operations for any of the equipments of the vehicle.

At an initialization step 100 of the method of the invention, it may be possible to input to the system information about an upcoming mission of the vehicle 1. This information can for example be a mission profile including a path for the vehicle along a route, and a set of expected uses, such as a set of delivery points and associated cargo loading/unloading which could require some amount of electricity to be delivered to power auxiliary equipment, or such as a set of garbage collection locations, with an associated expected mount of garbage to collect.

In a first step 101 of the method of the invention, one forecasts the upcoming operations of electrically fed auxiliary equipments of the vehicle 1. This may be done on the basis of the mission profile determined at step 100. If it appears on the information of the route that, at a stop of the truck, a garbage compaction will be executed, the garbage compactor 50 will be used and an operation of the power take-off 51 will be forecast. Step 101 is executed for all the electrically fed auxiliary equipments of the vehicle. For instance, if a steep downward slope is about to come in the following kilometers, a braking may be executed by the pneumatic braking systems 54 of the vehicle, thereby consuming air from the tank 24 which will need to be replenished by an electrically driven compressor.

Step 101 may also include a forecast of the upcoming electric production or consumption by the traction engine. For instance, for a same steep downward slope expected ahead, a regenerative braking may be executed by the traction electric machine used as a generator, thereby producing electric energy which can be directly used by the auxiliary equipment and/or stored in the battery set 22.

The period of future time during which operations are forecast is adjustable. It can depend on the type and size of vehicle, the number of auxiliary equipments to consider or the maximal electrical power that it can produce. For instance, this period of time can be set for a period of time between 30 seconds to ten minutes. That means for example a possible switching on of the lights in a tunnel in that period of time ahead is taken into account.

At a second step 102, an estimation of future electrical energy needs for the auxiliary equipments to execute the upcoming operations forecast at step 101 is executed by the electronic control unit 40. In this step, one determines, for example, the amount of electrical power and/or energy needed to execute an operation, the duration of this operation and the moment at which this operation will be executed. This may be done for all the operations forecast at step 101. Of course, if electric energy production or consumption by the traction electric machine is forecast at step 101 , an estimation of future electrical energy needs, either positive or negative, by the traction machine can also be estimated at step 102.

At the end of step 102, a time mapping of the electrical energy and/or power needs may be completed.

At the same time or before step 102, a step 103 of the method of the invention may be implemented with sensors 42 and 44 and the electronic control unit 40. In this step, the actual status of electrical power production of the vehicle, its electrical power consumption and the state of reserve of electrical energy on-board the vehicle can be determined thanks to signal S ₄₂ . This may include the electric power produced by the electric machine 20 or by a separate generator, the electrical power consumption of the electrically powered auxiliary equipments, such as garbage compactor 50, of the vehicle 1 , the electrical energy stored in the battery set 22 and/or the pneumatic energy stored in tank 24 transmitted by signal S ₄₄ .

After steps 102 and 103, a further step 104 of the method of the invention is implemented with electronic control unit 40. At this step 104, a comparison is made between the electrical energy needs estimated at step 102 and the actual status of electrical power production of the vehicle, its electrical power consumption and the state of reserve of electrical energy on-board the vehicle determined on step 103.

On the basis of the comparison made at step 104, a further step 105 of the method of the invention is implemented with electronic control unit 40. In this step, one determines if a shortage of electrical energy is forecast in the period of time for which an estimate took place at step 102. If the electrical energy needs estimated at step 102 are larger than the availabilities of electrical energy determined at step 103, a shortage may occur. The magnitude of the shortage may also be estimated, as well as its spread over a certain period of time. As a consequence, an extra-production of electrical energy will be needed.

Steps 102, 104 and 105 are for example implemented with a microchip integrated in the electronic control unit 40, or any other electronic component of the electronic control network 80.

If no shortage is forecast, the method goes back to steps 100 and 103.

If a shortage is forecast at step 105, extra torque is generated by the internal combustion engine 10 at a step 106 of the method of the invention. This extra torque is generated by increasing the ratio of the torque delivered by the internal combustion engine 10 with respect to the global torque delivered by the internal combustion engine 10 and the electric machine 20 to the driveline 30, as compared to a situation where no shortage of electrical energy is forecast. In fact, several scenarios are possible. In one of them, the part of electrical energy used to deliver torque to the driveline 30 is reduced and the electrical energy stored can be used to operate the auxiliary equipments at a subsequent time. In a second scenario, the electric machine 20 may deliver no torque to the driveline 30, the global torque delivered to the driveline 30 being then delivered solely by the internal combustion engine 10, and a large amount of electrical energy remaining then available to operate the auxiliary equipments. .

In a third scenario, an even higher torque is generated by the internal combustion engine so that the required of torque is delivered to the driveline, solely by the internal combustion engine 10, while the exceeding torque is used by the electric machine 20 to generate electrical energy which can be used to operate the auxiliary equipments and/or stored in the battery set 22 for being used by the auxiliary equipment at a further point in time.

In order to maximize electrical energy production by the internal combustion engine 10, the operation conditions of the engine may be set for a predetermined period by the electronic control unit 40, for what concerns its regime and its operation period(s). The period of time during which the extra torque is generated may be controlled in order to produce electrical energy at the best moment, i.e. at a point where a minimal amount of extra fuel is necessary to generate the extra torque. The best moment can be, for instance, a slight slope located one kilometer ahead of the place where the peak of electrical power need will occur.

An optimal use of the internal combustion engine 10 may be achieved by setting the ratio of the automatic gearbox 12 on the basis of the extra torque to be generated, thanks to signal S ₁₂ . For instance, during the extra torque generation, the ratio of the gearbox 12 may be reduced or increased so that extra torque is generated at a favorable torque/engine speed operating point where a minimal amount of extra fuel is necessary to generate the extra torque.

If no shortage were forecast, a restart and a production of extra torque by the internal combustion engine 10 could be needed during a climb at a high cost. In that case, the production of extra-electrical energy would provoke a fuel overconsumption.

The extra torque generated at step 106 can be distributed by different manners. For instance, a part of this extra torque can be delivered, at a step 107, to the driveline 30 of the hybrid vehicle 1 in order to save electrical energy normally delivered by the electric machine 20. If necessary, the totality of the extra torque generated can be delivered to the driveline 30. This can be done when the electrical energy reserves on-board the vehicle can be sufficient to provide, at the right time, the electrical energy needed by one or several electrically powered auxiliary equipments.

As described above, the extra torque generated at step 106 can be converted into energy which can be stored on-board the vehicle. In this case, the extra torque is delivered, at a step 108, to the electric machine 20 and electrical energy is generated. The electrical energy generated is stored, at a step 109, in the battery set 22 and may be delivered to at least one electrically-powered auxiliary equipment in the following minutes.

The extra torque can also be delivered to mechanically-driven compressor 28 and, in a step 1 10, converted into pneumatic energy in the form of the pressure of pressurized air stored in tank 24, at step 111. Pneumatic energy can be delivered at a further time point, as pressurized air, to the braking systems 54 in order to safely descend a steep slope.

According to another embodiment of the invention, forecasting means 60 can be integrated in the electronic control unit 40.

According to another embodiment of the invention, the totality of the extra torque generated at step 106 can be converted into energy and stored.

The invention is applicable with trucks, buses, cars and any other automotive hybrid vehicle.