Method for implementing a specific operating phase of the internal combustion engine of a hybrid vehicle

Abstract

The present invention relates to a method of implementing a particular phase of operation of a thermal engine of a hybrid vehicle comprising an electric machine powered by a battery.It comprises the following steps: assessing the need to initiate a particular operating phase and the duration of said phase; assessing the mechanical power capable of being produced by said internal combustion engine; determining the future trajectory of the motor vehicle; assessing the mechanical power required to ensure said trajectory and calculating the difference between this mechanical power and the mechanical power capable of being produced by said internal combustion engine; calculating the electrical power required to operate said electric machine as a function of said difference in mechanical power; and initiating said particular operating phase of said internal combustion engine as a function of said electrical power required to operate said electric machine and the electrical energy stored in said battery. Figure to be published with the abbreviation: Fig. 2.

Description

Title of the invention: Method for implementing a particular phase of operation of the internal combustion engine of a hybrid vehicle

[0001] The present invention relates to a method of controlling a hybrid motor vehicle comprising a thermal engine and an electric machine.

[0002] More particularly, the present invention relates to a method for conditionally implementing a particular phase of operation of the internal combustion engine of the hybrid vehicle.

[0003] Known hybrid vehicles include an internal combustion engine and at least one electric motor. The internal combustion engine is fueled by a combustible hydrocarbon, while the electric motor is powered by a battery.

[0004] Reference may be made to publication FR-A1-3022495, which describes such a drive system and an associated control method. In one of the embodiments disclosed by this publication, the internal combustion engine is associated with a first electric machine, which can be described as the primary machine, and which is capable of driving the vehicle on its own or in combination with the internal combustion engine, and furthermore with a second electric machine, which can be described as the secondary machine, which only serves to recharge a battery when driven by the internal combustion engine, but which cannot participate in driving the vehicle. Other hybrid drive systems are possible, in particular systems comprising several electric machines, for example two, which are capable of driving the vehicle.

[0005] The internal combustion engine has a catalyst at the exhaust outlet, which notably reduces the nitrogen oxides produced during the combustion reaction. However, this catalyst must be heated above a certain temperature threshold to be effective, that is, to achieve a sufficiently high rate of nitrogen oxide reduction.

[0006] Therefore, the coupling of the heat engine and the electrical machine(s) must be adjusted so that the heat engine operates according to particular operating phases allowing the catalyst to maintain its temperature.

[0007] On the other hand, there are specific operating phases of the internal combustion engine that are more demanding, for example when it comes to regenerating a particulate filter. This specific operating phase is then activated when the mass of fine particles stored inside the filter reaches a predefined threshold.

[0008] When the internal combustion engine is a spark-ignition engine, for example a gasoline engine, it is necessary to mechanically drive the internal combustion engine via the electric motor, while the fuel injection is cut off, so as to supply the particulate filter with air and consequently with oxygen. The internal combustion engine then acts as an air pump, which helps to promote the combustion of the fine particles stored in the filter.

[0009] Such a particular operating phase necessarily negatively impacts the vehicle's driving conditions, as it places a strain on the electric motor, which must simultaneously provide both the vehicle's propulsion and, in addition, drive the internal combustion engine. Therefore, it is essential to ensure, before initiating the regeneration of the particulate filter, that the battery is sufficiently charged.

[0010] On the other hand, if the motor vehicle begins an upward course, such a particular phase of operation may not be able to reach its end due to a lack of sufficient energy to be able to propel the vehicle.

[0011] Also, a problem which arises and which the present invention aims to solve is to provide a method of controlling a hybrid motor vehicle which makes it possible to start a particular phase of operation of the internal combustion engine without having it interrupted untimely.

[0012] In order to solve this problem, and according to a first objective, a method is proposed for the conditional implementation of a particular operating phase of a heat engine in a hybrid motor vehicle powertrain, said powertrain further comprising an electric machine powered by a battery capable of storing electrical energy. The method according to the invention comprises the following steps: the need to initiate a particular operating phase of said heat engine and the duration of said phase are evaluated; the mechanical power capable of being produced by said heat engine during said particular operating phase is evaluated; the future travel of the motor vehicle is determined during a period corresponding to said duration of said particular operating phase;The mechanical power required by the powertrain to ensure said future operation during said period is evaluated, and the difference between this mechanical power and the mechanical power capable of being produced by said internal combustion engine is calculated; the electrical power required for the operation of said electrical machine during said period is calculated as a function of said difference in mechanical power; and said particular operating phase of said internal combustion engine is initiated as a function of said calculated electrical power required for the operation of said electrical machine and the electrical energy stored in said battery.

[0013] Thus, a feature of the invention lies in taking into account the future trajectory of the motor vehicle during a time interval corresponding to the duration of the specific operating phase required by the internal combustion engine, in order to be able to trigger this operating phase. This future trajectory is determined, for example, by a GPS device programmed by the vehicle's driver. It allows for the definition of a temporal projection of the power required by the powertrain.

[0014] In other words, by taking this future race into account, it is determined whether the specific operating phase of the vehicle's internal combustion engine can be initiated, given the available battery capacity. Indeed, it is the electric motor that will have to supplement, at least partially, the internal combustion engine, which is temporarily unable to operate during this specific phase.

[0015] Thus, the said particular operating phase of the said internal combustion engine is preferentially triggered if, in addition, the said electrical energy stored in the said battery is greater than a minimum authorization threshold. Indeed, if the battery is completely discharged, the particular operating phase cannot be initiated in any case.

[0016] Also, according to a particularly advantageous embodiment of the invention, the electrical energy stored in said accumulator battery at the end of said period is further evaluated in order to trigger said particular operating phase of said internal combustion engine. More precisely, the electrical energy that will most likely be stored in the accumulator battery at the end of the particular operating phase of the internal combustion engine is evaluated. This is obviously made possible by determining the future stroke during the period corresponding to this phase.

[0017] Advantageously, said particular operating phase of said internal combustion engine is triggered if, in addition, said electrical energy stored in said battery at the end of said period is greater than a deactivation threshold. In this way, a completely discharged battery is avoided as soon as the particular operating phase ends.

[0018] According to a particularly advantageous embodiment of the invention, the method further comprises the following steps: the limiting mechanical power capable of being produced by said electric machine is supplied; the total time during which the mechanical power supplied by said electric machine is less than said difference in mechanical power is calculated; and said particular operating phase of said heat engine is triggered if, furthermore, said total time is less than a time threshold.

[0019] Indeed, the charge of the accumulator battery at the moment one decides to start The specific operating phase of the internal combustion engine is important to understand. However, it is possible that, despite a significant load, future driving conditions may be so severe that the electric motor's capabilities, even with a fully charged battery, will not allow it to operate in this specific phase. Therefore, the total duration for which this limitation exists is assessed, and the implementation of this specific operating phase may be permitted if this total duration is short and below the predefined threshold.

[0020] Furthermore, the torque allowed by the heat engine and the speed allowed by said heat engine during said particular operating phase are provided in order to evaluate said mechanical power capable of being produced by said heat engine. The calculations for evaluating the mechanical power of the heat engine capable of being produced will be detailed in the following description.

[0021] According to a particularly advantageous embodiment, the minimum and maximum torques allowed by the heat engine and the minimum and maximum speeds allowed by said heat engine during said particular phase of operation are provided in order to evaluate the minimum mechanical power and the maximum mechanical power capable of being produced by said heat engine.

[0022] Accordingly, the difference in mechanical power with said minimum mechanical power capable of being produced by said heat engine is calculated on the one hand, and the difference in mechanical power with said maximum mechanical power capable of being produced by said heat engine is calculated on the other hand.

[0023] According to one embodiment, said particular operating phase of said heat engine is triggered, depending on said calculated electrical power required for the operation of said electrical machine and the electrical energy stored in said battery of accumulators, or, if the need to trigger a particular operating phase of said heat engine is required for a duration exceeding another duration threshold.

[0024] Indeed, there are situations where a particular operating phase of the internal combustion engine is imperative, otherwise the engine's own operation may be compromised. Therefore, it is necessary to begin this phase regardless of the circumstances, even if it cannot be completed.

[0025] According to another object, a hybrid motor vehicle is proposed comprising, on the one hand, a thermal engine and an electric machine powered by a battery of accumulators capable of storing electrical energy and, on the other hand, an on-board computer adapted to implement the method as described above.

[0026] Other features and advantages of the invention will become apparent upon reading the following: The following description describes a particular embodiment of the invention, given by way of example but not limitation, with reference to the attached drawings on which:

[0027] [Fig. 1] is a flowchart showing the first steps of the method according to the invention; and,

[0028] [Fig.2] is a flowchart showing further steps of the method according to the invention.

[0029] The method according to the invention applies to a hybrid motor vehicle comprising a thermal engine and at least one electric machine. The thermal engine is powered by a conventional fuel, while the electric machine is powered by one or more rechargeable batteries.

[0030] The internal combustion engine requires specific operating conditions when, for example, activating the heating of a catalyst or the regeneration of its particulate filter, or carrying out self-diagnostics.

[0031] Also, to command and control these particular operating conditions, the vehicle is equipped with an on-board computer including a diagnostic interface allowing hardware diagnostics of the internal combustion engine and the main equipment of the vehicle.

[0032] Consequently, the on-board computer includes a program enabling the vehicle to be controlled in accordance with the invention, whenever a particular phase of vehicle operation is required.

[0033] Thus, when the mass of fine particles stored in the filter reaches a predetermined threshold, for example, the particulate filter must be regenerated. At this point, fuel injection is stopped, and the electric motor takes over to drive both the motor vehicle and the internal combustion engine. The latter then acts as a pump to supply air, and consequently oxygen, for the combustion of the fine particles.

[0034] Under these conditions, it is understood that the battery of accumulators must be sufficiently charged to be able to power the electric machine, which must produce a significant amount of mechanical power.

[0035] When internal combustion engine self-diagnostics are required, for some of them the internal combustion engine remains running. Consequently, it can contribute to the propulsion of the motor vehicle, to a certain extent, in addition to the electric motor. This mode of operation is called "parallel hybrid".

[0036] It is then understood that the implementation of these particular operating conditions requires stressing the electric machine more or less, and consequently, the battery of accumulators.

[0037] However, under certain driving conditions, the powertrain, including the internal combustion engine and the electric motor, is under considerable stress, for example when the The vehicle begins climbing a mountain pass. Also, for example, a regeneration of the particulate filter, started before the climb, may be interrupted before its completion if the battery is not sufficiently charged to power both the vehicle and the combustion engine during the climb.

[0038] Thanks to the method according to the invention, the future driving conditions of the motor vehicle are anticipated in order to decide whether or not to initiate one or another of the particular operating conditions.

[0039] These future driving conditions, in other words, the temporal projection of the power required by the powertrain, are developed from a pre-programmed GPS route or are determined by a driving assistance system according to the ADASIS protocol for example, which will allow the selection of a route from a plurality of possible routes, for example the route which will result in the highest power requirement.

[0040] The method then operates in three successive steps. First, in a first step, the minimum and maximum mechanical powers capable of being produced by the heat engine during the particular phase of operation are calculated.

[0041] Then, in a second step according to an iterative process, the energy level contained in the battery of accumulators at the end of the particular phase of operation is estimated, and also, the duration for which the constraints emitted by the heat engine would not be respected at the end of the particular phase if it were activated at a given time t.

[0042] And finally, in a third step, depending on the current energy contained in the accumulator battery and the estimated energy at the end of the particular phase requested by the heat engine or the duration during which the constraints emitted by the heat engine would not be respected, a decision is made to accept or not the request for the particular operating phase requested by the heat engine.

[0043] Thus, as soon as a particular operating phase of the heat engine is required, the first step of the method, illustrated in the flowchart of [Fig. 1], consists of calculating the maximum and minimum mechanical power that can be produced by the heat engine during the particular operating phase. To do this, in a first recording substep 10 of the first step, torque values ​​and rotational speed values ​​permitted by the heat engine during the particular operating phase to be implemented are recorded.

[0044] We therefore record, on the one hand, the maximum permissible torque value CPLmax and the minimum permissible torque value CPLmin, and on the other hand, the maximum rotational speed allowed VRmax and the minimum allowed rotation speed VRmin on the other hand.

[0045] Then, according to a second comparison substep 12 of the first step, if the maximum torque CPLmax and the minimum torque CPLmin are both positive or nu, in a third power calculation substep 14 of the first step, the minimum mechanical power PMCmin is calculated as the product of the minimum torque CPLmin and the minimum rotational speed VRmin multiplied by ir / 30 and the maximum mechanical power PMCmax is calculated as the product of the maximum torque CPLmax and the maximum rotational speed VRmax multiplied by ir / 30.

[0046] If, on the other hand, the maximum torque CPLmax and the minimum torque CPLmin are both negative, in accordance with a fourth comparison substep 16 of the first step, then in a fifth power calculation substep 18 of the first step, the minimum mechanical power PMCmin is calculated as the product of the minimum torque CPLmin and the maximum rotational speed VRmax multiplied by ir / 30 and the maximum mechanical power PMCmax is calculated as the product of the maximum torque CPLmax and the minimum rotational speed VRmin multiplied by ir / 30.

[0047] But, if the maximum torque CPLmax and the minimum torque CPLmin are of opposite signs, then in a sixth sub-step of power calculation 20 of the first step, the minimum mechanical power PMCmin is calculated as the product of the minimum torque CPLmin and the maximum rotational speed VRmax multiplied by ir / 30 and the maximum mechanical power PMCmax is calculated as the product of the maximum torque CPLmax and the maximum rotational speed VRmax multiplied by ir / 30.

[0048] When the first step illustrated in [Fig.1] is completed, the maximum mechanical power PMCmax and minimum mechanical power PMCmin allowed by the heat engine during the particular phase of operation are known, and these values ​​will then be used in the second step, which consists both of estimating the energy contained in the battery at the end of the duration of the particular phase of operation and of establishing the potential duration during which the minimum and maximum power allowed by the heat engine cannot be respected.

[0049] First, this second step, called the iterative step, operates according to a loop. It is schematically illustrated in the flowchart shown in [Fig.2], delimited by a dashed line 21.

[0050] The implementation of this second step requires supplying the loop not only with the maximum mechanical power PMCmax and minimum mechanical power PMCmin, calculated during the first step, but also with the time projection of the power PTPW required by the powertrain, developed, for example, from a GPS route pre-programmed by the driver, and furthermore with the time required to the realization of the particular operating phase DPPF, which duration DPPF is estimated and transmitted by the internal combustion engine according to its own needs.

[0051] The number of iterations of the NbBCL loop is then the quotient of the time required to carry out the particular operating phase DPPF and a temporal recurrence X of the entry authorization strategy in the particular operating phase.

[0052] Thus, for each iteration until the number NbBCL is reached, in addition to the maximum mechanical powers PMCmax and minimum mechanical powers PMCmin allowed by the heat engine during the particular phase of operation and provided in the first step, the corresponding value PTPW of the time projection of the powers PTPW(t) is also provided.

[0053] Then, according to a first calculation sub-step 26 of the second step, the minimum power PElecMin which the electric machine, or where applicable, the plurality of electric machines, must be provided is calculated on the one hand as the difference between the maximum mechanical power allowed by the heat engine PMCmax and the power required by the powertrain, in other words the value PTPW of the time projection of the powers, and on the other hand the maximum power which the electric machines must provide PElecMax is calculated as the difference between the minimum mechanical power allowed by the heat engine PMCmin and the power required by the powertrain PTPW.

[0054] According to a second calculation substep 28 of the second step, using the maximum power PElecMax and minimum power PElecMin, the total duration TLPMinMax is calculated where the heat engine does not have its minimum and maximum power limits respected.

[0055] If the minimum power that the electric machine PElecMin must supply is greater than the maximum mechanical power achievable by the electric machine PMElecMax and supplied in the second stage, or if the maximum power that the electric machine PElecMax must supply is less than the minimum mechanical power achievable by the electric machine PMElecMax, then this implies that the electric machine cannot produce the power necessary to meet the minimum and maximum power limits set by the internal combustion engine PMCmin, PMCmax, and the driver's input, i.e., the corresponding value PTPW of the power time projection. The driver's input corresponds to the desire to accelerate, which is translated into a power or torque command at the wheel for driving the vehicle.

[0056] Also, under these conditions, the time counter previously initialized to "0" is then incremented by the temporal recurrence of strategy X with respect to its previous value in the loop.

[0057] It will be noted that the maximum mechanical power achievable by the PMElecMax electric machine includes its mechanical limits and the discharge power limits of the storage batteries. Likewise, the minimum mechanical power achievable by the PElecMin electric machine includes its mechanical limits and the charging power limits of the storage battery.

[0058] According to a third substep 30 of the second step, the electrical power to be consumed or produced PElecReq by the electric machine is calculated as a function of the energy difference between a nominal target energy of the vehicle ENC and the energy estimated at each time step of the loop EEst, the calculation of which will be established below. The difference between these two ENC energies, EEst, is entered into a parameterizable table, thus allowing the definition of the estimated optimal electrical power level for charging / discharging.

[0059] According to a fourth sub-step 32 of the second step, the electrical power consumed or produced by the electrical machine PElec is calculated as a function of the mechanical power limits, PElecMax, PElecMin, which the electrical machine must supply, and the electrical power to be consumed or produced PElecReq by the electrical machine.

[0060] Initially, the mechanical power limits PElecMax, PElecMin achievable by the electric machine are limited respectively to the maximum mechanical powers PMElecMax and minimum PMElecMin achievable by the electric machine, i.e. to the maximum and minimum mechanical powers of the electric machine allowing compliance with the corresponding value PTPW of the time projection of the powers and the maximum and minimum powers allowed by the heat engine PMCmax, PMCmin, consolidated with the physical limits of the electric machine.

[0061] These consolidated mechanical powers are denoted respectively PMElecCsMax and PMElecCsMin and are equal to respectively: MIN [SMElecMax; MAX (PElecMax; PMElecMin)]; MIN [SMElecMax; MAX (PElecMin; PMElecMin)].

[0062] In a second step, these mechanical powers of the electric machine PMElecCsMax and PMElecCsMin are respectively converted into maximum and minimum electrical powers PElecWMax and PElecWMin by means of the equations below: PElecWMax = PMElecCsMax + FPP(PMElecCsMax)2; PElecWMin = PMElecCsMin + FPP(PMElecCsMin)2; in which the second-order, parameterizable FPP coefficient is a power loss factor for the electric machine and the battery. The value of this coefficient depends on the sign of the mechanical power considered.

[0063] In a third step, the electrical power to be consumed or produced PElecReq by the electrical machine is consolidated by means of the allowed and calculated power field above: PElec WMax and PElecWMin.

[0064] This then results in the final estimated electrical power PElec, achieved by the electric machine on the current iteration in the loop.

[0065] Finally, based on this estimated final electrical power PElec, we integrate, according to a fifth sub-step of integration 34 of the second step, the estimated energy value EEst at each iteration of the loop from the estimated energy of the previous iteration and also from the estimated final electrical power PElec factor of the aforementioned time recurrence X.

[0066] To initialize this second iterative step, the estimated energy value for the first iteration is the current energy value in the accumulator battery: ENCrt.

[0067] When the maximum number of iterations of the NbBCL loop is reached, then EEst represents the estimated energy at the end of the particular operating phase required by the heat engine, while TLPMinMax represents the total time during which the particular operating phase of the heat engine does not allow the minimum and maximum torques and speeds required by the heat engine, CPLmax, CPLmin and VRmax, VRmin, to be met.

[0068] Thus, in a third and final determination step 36, it is determined whether the particular operating phase of the required heat engine can be authorized, and this is determined not only based on the estimated energy at the end of the particular operating phase required by the heat engine EEst and the total duration during which the particular operating phase of the heat engine does not allow compliance with the minimum and maximum torques and speeds TLPMinMax, thanks to the second step, but also in accordance with predefined values ​​of minimum authorization threshold SMinAuto, deactivation threshold SDésact and adjustable duration threshold STempR.

[0069] Thus, this phase is authorized insofar as the internal combustion engine requires a particular operating phase and if the current energy in the accumulator battery ENCrt is greater than a predefined minimum authorization threshold SMinAuto, on the one hand; and furthermore, if the estimated energy value EEst is greater than a deactivation threshold SDésact also predefined, and the total duration TLPMinMax during which the particular operating phase of the internal combustion engine does not allow compliance with the minimum and maximum torques and speeds required is less than an adjustable duration threshold STempR; or if the particular operating phase of the internal combustion engine has been required for a duration greater than a configurable threshold.

[0070] On the other hand, the particular operating phase of the internal combustion engine is not permitted, if of course it is not required or if the current energy in the ENCrt accumulator battery is less than the SDésact deactivation threshold.

Claims

Demands

1. A method for conditionally implementing a particular operating phase of a heat engine of a hybrid motor vehicle powertrain, said powertrain further comprising an electric machine powered by a battery capable of storing electrical energy, characterized in that it comprises the following steps: - evaluating the need to initiate a particular operating phase of said heat engine and the duration of said phase; - evaluating the mechanical power capable of being produced by said heat engine during said particular operating phase; - determining the future travel of the motor vehicle during a period corresponding to said duration of said particular operating phase;- the mechanical power required by the powertrain to ensure the said future race during the said period is evaluated, and the difference between this mechanical power and the mechanical power capable of being produced by the said internal combustion engine is calculated; - the electrical power required for the operation of the said electric machine during the said period is calculated as a function of the said difference in mechanical power; and the said particular operating phase of the said internal combustion engine is triggered as a function of the said calculated electrical power required for the operation of the said electric machine and the electrical energy stored in the said battery.

2. Method according to claim 1, characterized in that said particular operating phase of said heat engine is triggered if furthermore said electrical energy stored in said battery of accumulators is greater than a minimum authorization threshold (SMinAuto).

3. Method according to claim 1 or 2, characterized in that the electrical energy stored in said accumulator battery at the end of said period (EEst) is further evaluated in order to be able to trigger said particular operating phase of said heat engine.

4. Method according to claim 3, characterized in that said particular operating phase of said heat engine is triggered if in Furthermore, the electrical energy stored in the battery at the end of the period (EEst) is greater than a deactivation threshold (SDésact).

5. A method according to any one of claims 1 to 4, characterized in that it further comprises the following steps: - the limiting mechanical power capable of being produced by said electric machine is supplied; - the total time during which the mechanical power supplied by said electric machine is less than said difference in mechanical power is further calculated; and, - said particular operating phase of said heat engine is triggered if, furthermore, said total time is less than a time threshold (STempR).

6. Method according to any one of claims 1 to 5, characterized in that the torque allowed by the heat engine and the speed allowed by said heat engine during said particular phase of operation are provided in order to evaluate said mechanical power capable of being produced by said heat engine.

7. Method according to claim 6, characterized in that the minimum and maximum torques allowed by the heat engine and the minimum and maximum speeds allowed by said heat engine are provided during said particular phase of operation in order to evaluate the minimum mechanical power and the maximum mechanical power capable of being produced by said heat engine.

8. Method according to claim 7, characterized in that the difference in mechanical power is calculated with said minimum mechanical power capable of being produced by said heat engine, on the one hand, and the difference in mechanical power with said maximum mechanical power capable of being produced by said heat engine, on the other hand.

9. A method according to any one of claims 1 to 6, characterized in that said particular operating phase of said heat engine is triggered, depending on said calculated electrical power required for the operation of said electrical machine and the electrical energy stored in said battery, or, if the need to trigger a particular operating phase of said heat engine is required for a duration greater than another duration threshold.

10. Hybrid motor vehicle comprising, on the one hand, a thermal engine and an electric machine powered by a battery of accumulators capable of storing electrical energy and, on the other hand, an on-board computer adapted to implement the method according to any one of claims 1 to 9.

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