METHOD FOR REGENERATION OF A PARTICULATE FILTER FROM A HYBRID VEHICLE

Abstract

One aspect of the invention relates to a method 100 for regenerating a hybrid vehicle particulate filter, comprising the steps of: Determining 101 the maximum torque that a rotating electrical machine can provide; Determining 102 the loss torque of an internal combustion engine when the internal combustion engine is in fuel cut-off mode; Determining 103 the minimum torque that a driver can demand; Determining 104 the torque demanded by a driver; If the maximum torque that the rotating electrical machine can provide is able to compensate, on the one hand, for the loss torque plus the minimum torque and, on the other hand, for the loss torque plus the demanded torque; Controlling 105 the fuel cut-off of the internal combustion engine; and Providing 106 the demanded torque by means of the rotating electrical machine. Figure 2.

Description

Title of the invention: METHOD FOR REGENERATION OF A PARTICLE FILTER OF A HYBRID VEHICLE

[0001] One aspect of the invention relates to a method for regenerating a hybrid vehicle particulate filter. Another aspect of the invention relates to a hybrid vehicle arranged to carry out the steps of the method.

[0002] The invention finds a particularly interesting application in the field of motor vehicles with electric hybridization, that is to say comprising a thermal engine and at least one rotating electrical machine associated with a power battery.

[0003] The invention intends to propose a solution for optimally managing the regeneration of particle filters placed in the exhaust line of combustion gases emitted by the thermal engine of a hybrid vehicle.

[0004] Car manufacturers are striving to reduce or even eliminate pollution from their vehicles by various means, for example by reducing fuel consumption and / or filtering exhaust gases.

[0005] Particle filters were then developed and are now being fitted to more and more vehicles, whether they have petrol or diesel engines. These filters, whether catalyzed or not, are generally made up of cylindrical ceramic blocks forming a multitude of parallel channels of small diameters (of the order of ten microns). The exhaust gases pass through the filter and the particles they contain are trapped in the channels. These particle filters function correctly but have the disadvantage of having to be regenerated regularly to eliminate the particles which tend to obstruct the filter channels.

[0006] Particle removal is generally carried out by combustion by heating the filter. When the temperature of the particulate filter reaches a threshold, and in the presence of oxygen, then the particles will burn and the filter will discharge the particles.

[0007] For a conventional motor vehicle, i.e. with a thermal engine only, when the particulate filter is sufficiently charged, strategies for controlling the thermal engine intervene to raise the temperature of the filter via, for example, a degradation of the combustion of the thermal engine in order to release more thermal energy to heat the filter. Once the particulate filter is hot, i.e. when it has reached or exceeded its regeneration threshold temperature allowing the combustion of the particles, the supply of oxygen is done either during the deceleration phases depending on a demand for engine power from the driver, or by injecting a mixture lean in fuel, therefore rich in oxygen, either by injecting air into the exhaust line by specific means. In a hybrid motor vehicle, for example one with an electric motor that does not release the heat of a thermal engine, the torque provided by the electric motor has the effect of reducing the frequency of life situations allowing the regeneration of the particulate filter such as those envisaged in a conventional motor vehicle.

[0008] For example, document FR-B1-3077341 discloses a method for controlling the regeneration of a particle filter of a hybrid-powered vehicle proposing a plurality of strategies for controlling the regeneration of the particle filter combining control of a thermal engine with an electric motor. However, during a regeneration phase, when the electric motor is saturated, the thermal engine is used to satisfy the driver's torque demand. In such a situation, the thermal engine is not in injection cut-off, and its torque is equal to the difference between the torque supplied by the electric motor and the torque requested by the driver. This operating point is not optimal because the thermal engine provides little torque, and the energy consumed by the electric motor is maximum.

[0009] The aim of the invention is to overcome the drawbacks of the prior art by proposing a method for regenerating a hybrid vehicle particle filter making it possible to avoid positioning the thermal engine at a non-optimal torque point to regenerate the particle filter.

[0010] In this context, the invention thus relates, in its broadest acceptance, to a method for regenerating a particle filter of a hybrid vehicle, the method being remarkable in that it comprises, when the particle filter has a particle rate greater than a first threshold particle rate and a temperature greater than a threshold temperature, the steps, executed by vehicle control means, of: • Determine the maximum torque that a rotating electrical machine of the vehicle can provide; • Determine a couple of losses of a vehicle's thermal engine when the thermal engine is in injection cut-off; • Determine a minimum torque that a vehicle driver can request • Determine a torque requested by a vehicle driver; • If the maximum torque that the rotating electrical machine can provide is able to compensate, on the one hand, the loss torque added to the minimum torque and, on the other hand, the loss torque added to the requested torque; • Control an injection cut-off of the thermal engine; and • Provide the requested torque by means of the electrical machine rotating.

[0011] Thanks to the method according to the invention, before controlling an injection cut-off of the thermal engine, it is ensured that the rotating electrical machine is able to compensate, on the one hand, the torque losses of the thermal engine supplied by the thermal engine when it is in injection cut-off to which is added the minimum torque that the driver of the vehicle can request when releasing the foot and, on the other hand, the torque losses of the thermal engine to which is added the torque currently requested by the driver. Thus, if the torque requested by the driver does not change, it is certain that the rotating electrical machine is able to satisfy the driver's wish while placing the thermal engine in injection cut-off in order to regenerate the particle filter.Furthermore, if the driver completely releases the accelerator pedal, it is also certain that the rotating electrical machine is able to satisfy the driver's wish while placing the engine in injection cut-off in order to regenerate the particle filter.

[0012] In addition to the characteristics which have just been mentioned in the preceding paragraph, the method according to this aspect of the invention may have one or more complementary characteristics among the following, considered individually or according to all technically possible combinations.

[0013] According to a non-limiting aspect of the invention, • The step of controlling an injection cut-off is carried out by gradually reducing an engine torque supplied by the thermal engine until reaching the determined loss torque, and • The step of providing the requested torque is carried out by compensating for the reduction in engine torque by a simultaneous progressive increase in machine torque provided by the rotating electrical machine.

[0014] According to a non-limiting aspect of the invention, the maximum torque that the rotating electrical machine can provide is a function of a state of charge of a power battery arranged to electrically power the rotating electrical machine and of characteristics of the rotating electrical machine.

[0015] According to a non-limiting aspect of the invention, the maximum torque that the rotating electrical machine can provide is also a function of a state of wear of the rotating electrical machine.

[0016] According to a non-limiting aspect of the invention, the method comprises a step, executed by the control means, of stopping the step of controlling an injection cut-off of the heat engine if the particle rate is lower than a second threshold particle rate lower than the first threshold particle rate.

[0017] Another aspect of the invention relates to a hybrid vehicle comprising control means arranged to carry out the steps of the method according to any one of the aforementioned aspects of the invention.

[0018] According to a non-limiting aspect of the invention, the hybrid vehicle comprises a power battery of the 48V or 400V type.

[0019] The invention and its various applications will be better understood by reading the following description and examining the accompanying figures.

[0020] [Fig-1] illustrates, schematically, a hybrid vehicle according to a non- limiting of the invention.

[0021] [Fig.2] shows, schematically, the steps of a method according to a non- limiting of the invention.

[0022] [Fig.3] is a representative graph of torque curves.

[0023] Unless otherwise specified, the same element appearing in different figures has a single reference.

[0024] [Fig.l] schematically illustrates a hybrid vehicle 1 conforming to a non-limiting implementation of the invention.

[0025] In a non-limiting manner, the hybrid vehicle 1 may be formed by a hybrid vehicle of the 48V or 400V type.

[0026] The hybrid vehicle 1 comprises: • A thermal engine 2; • An exhaust line 3 for the combustion gases emitted by the heat engine 2 • A particle filter 4 placed in the exhaust line 3 of the combustion gases emitted by the heat engine 2; • A clutch 5; • A rotating electrical machine 6; • A 7 speed gearbox; • A front wheel shaft 8; • A 400V type power battery 9 arranged to electrically supply the rotating electrical machine 6; • Means of control 10.

[0027] In this non-limiting exemplary embodiment, when the clutch 5 is closed, the heat engine 2 is mechanically connected to the front wheel shaft 8 and is able to transmit a torque to the front wheel shaft 8.

[0028] Furthermore, when the rotating electrical machine 6 is electrically powered by the power battery 9, the rotating electrical machine 6 is able to transmit torque to the front wheel shaft 8.

[0029] In other words, the heat engine 2 and the rotating electrical machine 6 can be operated simultaneously or independently of each other to transmit torque to the front wheel shaft 8.

[0030] The control means 10 are arranged to execute the steps of the method for regenerating a hybrid vehicle particle filter according to a non-limiting aspect of the invention illustrated in [Fig.2].

[0031] In a non-limiting manner, the control means 10 may be formed by a vehicle control unit (better known by the acronym VCU for Vehicle Control Unit in English).

[0032] [Fig.2] shows a step diagram of an embodiment of the method 100 according to the invention and [Fig.3] shows torque curves as a function of time making it possible to illustrate the steps of the method 100.

[0033] More particularly, [Fig.3] illustrates: • A maximum torque Cl that the rotating electrical machine 6 can provide; • A C2 engine torque provided by the thermal engine 2; • A couple of losses C3 from the thermal engine 2; • A minimum torque C4 that can be requested by a driver of vehicle 1; • A torque requested C5 by a driver of vehicle 1; and • A machine torque C6 provided by the rotating electric machine 6.

[0034] The steps of the method 100 are executed by the control means 10 when the particle filter 4 has a particle rate greater than a first threshold particle rate and a temperature greater than a threshold temperature. For this purpose, sensors can transmit particle rate and temperature measurements to the control means 10 in order to compare them with the first threshold particle rate and the threshold temperature.

[0035] The method 100 comprises a step of determining a maximum torque Cl that the rotating electrical machine 6 can provide.

[0036] In a non-limiting implementation, the maximum torque C1 that the rotating electrical machine 6 can provide may be a function of a state of charge of the power battery 9 and of characteristics of the rotating electrical machine 6.

[0037] The state of charge, also known by the acronym SoC (for State of Charge in English) can be provided by a battery control system (not illustrated) to the control means 10. The characteristics of the rotating electrical machine 6 can for example be recorded by the manufacturer in the control means 10. These characteristics can for example correspond to a maximum torque Cl that the rotating electrical machine 6 can provide at a given operating temperature.

[0038] The maximum torque C1 that the rotating electrical machine 6 can provide may also be a function of a state of wear of the rotating electrical machine 6. In a non-limiting manner, this state of wear may be determined by a number of hours of use of said rotating electrical machine 6 or a total distance traveled by the vehicle 1.

[0039] The method 100 also comprises a step, executed by the control means 10, of determining 102 a loss torque C3 of the heat engine 2. This loss torque C3 corresponds to the torque supplied by the heat engine 2 when it is in injection cut-off. It can be recorded by the manufacturer in the control means 10.

[0040] The method 100 also comprises a step, executed by the control means 10, of determining 103 a minimum torque C4 that a driver of the vehicle 1 can request. This minimum torque C4 corresponds to releasing the accelerator pedal of the vehicle 1. It can be recorded by the manufacturer in the control means 10 and can be a function of a slope of the road on which the vehicle is located and / or a load of the vehicle.

[0041] The method 100 also comprises a step, executed by the control means 10, of determining a torque requested C5 by a driver of the vehicle 1. This torque request can be measured by a sensor of movement of the accelerator pedal of the vehicle 1, then transmitted to the control means 10.

[0042] If the maximum torque C1 that the rotating electrical machine 6 can provide is capable of compensating, on the one hand, the loss torque C3 of the thermal engine 2 when it is in injection cut-off to which is added the minimum torque C4 that the driver is likely to request and, on the other hand, the loss torque C3 to which is added the torque requested C5 by the driver of the vehicle 1, the method 100 comprises the steps of: • Control 105 an injection cut-off of the thermal engine 2; • Provide 106 the requested torque C5 by means of the rotating electrical machine 6.

[0043] The injection cut-off consists of a system which cuts off the supply of fuel to the injection pump of the thermal engine 2. This injection cut-off phase will allow the supply of oxygen to the particle filter 4 and therefore to initiate its regeneration.

[0044] In a non-limiting implementation illustrated in zone Z of [Fig. 3], the step 105 of controlling an injection cut-off is executed by progressively reducing the engine torque C2 supplied by the heat engine 2 until reaching the determined loss torque C3. The step 106 of supplying the requested torque C5 is, for its part, executed by compensating for the reduction in engine torque C2 by a simultaneous progressive increase in the machine torque C6 supplied by the rotating electrical machine 6.

[0045] In summary, when the particle filter 4 has a particle rate greater than a first threshold particle rate, a temperature greater than a threshold temperature and the maximum torque C1 that the rotating electrical machine 6 can provide is able to compensate on the one hand, the loss torque C3 to which the torque minimum C4 and, on the other hand, the loss torque C3 to which we add the requested torque C5, the control means 10: • Control 105 an injection cut-off of the thermal engine 2; • Provide 106 the requested torque C5 by means of the rotating electric machine 6.

[0046] In the illustrated example, these steps of driving 105 and supplying 106 begin at the line Za and end at the line Zb.

[0047] Indeed, at the level of the straight line Za, the maximum torque Cl that the rotating electrical machine 6 can provide is able to compensate for the addition of the loss torque C3 and the torque requested C5 by the driver of the vehicle 1. Thus, if there is an injection cut-off positioning the engine torque C2 on the loss torque C3 and the torque requested C5 by the driver does not change, it is certain that the capacity of the rotating electrical machine 6 is sufficient to place the thermal engine 2 in injection cut-off.

[0048] At the level of the straight line Za, the maximum torque C1 that the rotating electrical machine 6 can provide is also able to compensate for the addition of the loss torque C3 and the minimum torque C4 that the driver is likely to request. Thus, if there is an injection cutoff and the torque C5 requested by the driver decreases until it reaches the minimum torque C4, it is certain that the capacity of the rotating electrical machine 6 is sufficient to place the thermal engine 2 in injection cutoff.

[0049] From the line Zb, as the torque requested C5 by the driver of vehicle 1 decreases further, the machine torque C6 is also decreased.

[0050] The method further comprises a step, executed by the control means 10, of stopping 107 the step of controlling 105 an injection cutoff of the heat engine 2 if the particle rate is lower than a second threshold particle rate lower than the first threshold particle rate.

[0051] For this purpose, sensors can transmit particle rate measurements to the control means 10 in order to compare them to the second threshold particle rate.

[0052] The various aspects of the invention mentioned above have numerous advantages. Among these, we can cite: • Satisfy the driver's torque demand; and • Effectively reduce the particle rate of a particulate filter.

Claims

Claims

1. Method (100) for regenerating a particle filter (4) of a hybrid vehicle (1), said method (100) being characterized in that it comprises, when said particle filter (4) has a particle rate greater than a first threshold particle rate and a temperature greater than a threshold temperature, the steps, executed by control means (10) of said vehicle (1), of: • Determining (101) a maximum torque (Cl) that can be supplied by a rotating electrical machine (6) of said vehicle (1); • Determining (102) a loss torque (C3) of a heat engine (2) of said vehicle (1) when said heat engine (2) is in injection cut-off; • Determining (103) a minimum torque (C4) that can be requested by a driver of said vehicle (1); • Determining (104) a requested torque (C5) by a driver of said vehicle (1);• If said maximum torque (Cl) that can be supplied by said rotating electrical machine (6) is able to compensate, on the one hand, said loss torque (C3) added to said minimum torque (C4) and, on the other hand, said loss torque (C3) added to said requested torque (C5); • Control (105) an injection cut-off of said thermal engine (2); and • Supply (106) said requested torque (C5) by means of said rotating electrical machine (6).;

2. Method (100) according to the preceding claim, characterized in that: • The step of controlling (105) an injection cut-off is executed by progressively reducing an engine torque (C2) supplied by the thermal engine (2) until reaching the determined loss torque (C3), and • The step of supplying (106) the requested torque (C5) is executed by compensating for the reduction of said engine torque (C2) by a simultaneous progressive increase in a machine torque (C6) supplied by the rotating electrical machine (6).

3. Method (100) according to any one of the preceding claims, characterized in that the maximum torque (Cl) that the rotating electrical machine (6) can provide is a function of a state of charge of a power battery (9) arranged to electrically supply said rotating electrical machine (6) and of characteristics of said rotating electrical machine (6).

4. Method (100) according to the preceding claim, characterized in that the maximum torque (Cl) that the rotating electrical machine (6) can provide is also a function of a state of wear of said rotating electrical machine (6).

5. Method (100) according to any one of the preceding claims, characterized in that it comprises a step, executed by the control means (10), of stopping (107) the step of controlling (105) a cut-off of injection of the heat engine (2) if the particle rate is lower than a second threshold particle rate lower than the first threshold particle rate.

6. Hybrid vehicle (1) characterized in that it comprises control means (10) arranged to execute the steps of the method (100) according to any one of the preceding claims.

7. Hybrid vehicle (1) according to the preceding claim, characterized in that it comprises a power battery (9) of the 48V or 400V type.

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