METHOD FOR POWERING A HEATING DEVICE FOR A CATALYTIC CONVERTER

Abstract

The invention relates to a device for powering a heating device (21) of a catalytic converter (20) for a motor vehicle (1) having a thermal engine (M), said vehicle (1) comprising an electrical network (10), a battery (30), a DC/DC voltage converter (80), a first switch (60), a second switch (70) and an electric machine (40), the battery (30) being suitable for operating in a recharging mode, in which it stores electrical energy, and in a discharging mode, in which it supplies electrical energy, characterized in that the first switch (60) is coupled to the catalytic converter (20) and the electric machine (40) and is suitable for being in either a closed-circuit position electrically coupling the catalytic converter (20) and the electric machine (40) to heat up the catalytic converter (20), or in an open-circuit position enabling the electrical isolation of the catalytic converter (20) from the electric machine (40), the second switch (70) is coupled, on the one hand, to the electric machine (40) and to the first switch (60), and, on the other hand, to the DC/DC voltage converter (80), the second switch (70) is suitable for being in either a closed-circuit position enabling the electrical coupling between the electric machine (40) and the battery (30) through the DC/DC voltage converter (80) to enable it to recharge, or in an open-circuit position electrically isolating the battery from the electric machine, or in an open-circuit position electrically isolating the battery (30) from the electric machine (40).

Description

TECHNICAL FIELD

The invention relates to the field of a motor vehicle comprising a thermal engine and equipped with a depollution device having a heating device. The invention also relates to a method for powering the heating device of the depollution control.

PRIOR ART

Nowadays, a motor vehicle having a thermal engine comprises a catalyst, also known as a catalytic converter, for depolluting the exhaust gases emitted by the thermal engine of the vehicle.

The catalytic converter can, in particular, be an electrically heated catalyst (EHC). This type of catalytic converter comprises a heating device which rapidly increases the temperature in the catalytic converter in order to control gas emissions even when the motor vehicle is cold, i.e. when starting. The heating device comprises, in particular, a resistor for heating purposes.

Such a vehicle generally comprises a battery and an electric machine, more precisely a DC machine. The DC machine is able to operate in two operating modes: a motor mode in which the DC machine converts electrical energy into mechanical energy in order to start the thermal engine, and a generator mode in which the electric machine converts the mechanical energy of rotation of the engine into electric energy stored in the battery. The battery is, for example, a 12-volt, 24-volt, or 48-volt battery.

The heating device is coupled to an electrical network via a specific control device and is configured to connect or not connect the heating device to the electrical network and therefore heat or not heat the catalytic converter.

Substantial power is needed more or less instantaneously in order to achieve efficiency and responsiveness of the catalytic converter resistor. A 48-volt battery is commonly used for this purpose. This battery has enough available power to allow heating of the resistor when necessary to allow the gas to be depolluted.

A major disadvantage of this solution is the need to have vehicle electronics compatible with such a voltage level, in the case 48 volts. This solution requires the use of additional circuits which incur an additional cost.

A need therefore exists for a solution allowing these disadvantages to be at least partially overcome.

SUMMARY OF THE INVENTION

For this purpose, the invention relates to a device for powering a heating device of a catalytic converter for a motor vehicle having a thermal engine, said vehicle comprising an electrical network, a battery, a DC/DC voltage converter, a first switch, a second switch and an electric machine, the battery being suitable for operating in a recharging mode, in which it stores electrical energy, and in a discharging mode, in which it supplies electrical energy. The first switch is coupled to the catalytic converter and the electric machine and is suitable for being in either a closed-circuit position electrically coupling the catalytic converter and the electric machine to heat up the catalytic converter, or in an open-circuit position enabling the electrical isolation of the catalytic converter from the electric machine, the second switch is coupled, on the one hand, to the electric machine and to the first switch, and, on the other hand, to the DC/DC voltage converter, the second switch is suitable for being in either a closed-circuit position enabling the electrical coupling between the electric machine and the battery through the DC/DC voltage converter to enable it to recharge, or in an open-circuit position electrically isolating the battery from the electric machine.

The electric machine is advantageously suitable for delivering a voltage of 24 volts or 48 volts.

In one exemplary embodiment, the DC/DC voltage converter is a step-down voltage converter.

The DC/DC voltage converter is, for example, a two-way converter.

In another exemplary embodiment, the battery is a 12-volt battery.

In a second aspect, the invention relates to a method for powering a heating device for a motor vehicle having a thermal engine, said vehicle comprising an electrical network, a catalytic converter capable of depolluting the exhaust gases emitted by the engine and comprising an electric heating device, a battery, a DC/DC voltage converter, an electric machine, a first switch suitable for switching between a closed-circuit state and an open-circuit state, and a second circuit switch suitable for switching between a closed-circuit state and an open-circuit state. Said method comprises the following steps:

• • e1) checking an open-circuit condition of the first switch corresponding to a catalytic converter not electrically heated,
  • e2) detecting a need to activate the electric heating device of the catalytic converter,
  • e3) determining the electrical power required to reach a threshold temperature (Tthreshold) of the catalytic converter and determining the electrical power of the battery, if the battery power is below a charge level Nthresholdcharge, then proceeding to a fourth step e4); if the battery power is above a charge level Nthresholdcharge, then proceeding to a fifth step e5);
  • e4) checking that the second switch is in an open-circuit state and then positioning the first switch in the closed-circuit state to couple the electric machine to the heating device,
  • e6) controlling the electric machine in order to generate an electrical power allowing the catalytic converter to heat up,
  • e7) checking the temperature of the catalytic converter,
  • e8) switching off the heating device and positioning the second switch in an open-circuit state when the temperature of the catalytic converter is at least equal to the threshold temperature,
  • e5) comparing the quantity of electrical power required to heat up the catalytic converter to reach the threshold temperature with the electrical power deliverable by the battery and by the electric machine, if the electrical power deliverable by the battery is sufficient, then proceeding to a ninth step e9), if the electrical power deliverable by the electric machine is sufficient, then proceeding to a tenth step e10), if the electrical power required to heat up the catalytic converter to reach the threshold temperature is greater than the electrical power deliverable by the electric machine and the electrical power deliverable by the battery, then proceeding to an eleventh step e11),
  • e9) switching the second switch to a closed state and switching the first switch to an open state,
  • e12) controlling the DC/DC converter in order to generate the electrical power required by the heating device to heat up the catalytic converter,
  • e10) switching the second switch to an open state and switching the first switch to a closed state,
  • e15) controlling the electric machine in order to generate the electrical power required by the heating device to heat up the catalytic converter, e11) controlling the second switch to a closed state and switching the first switch to a closed state,
  • e18) controlling the electric machine and the battery in order to generate the electrical power required by the heating device to heat up the catalytic converter.

DESCRIPTION OF THE DRAWINGS

Further characteristics and advantages of the invention will become more clearly apparent from a reading of the description below. This description is purely illustrative and should be read with reference to the attached drawings, in which:

FIG. 1 shows an embodiment of the vehicle according to the invention;

FIG. 2 shows a more detailed embodiment of the invention;

FIG. 3 illustrates an exemplary embodiment of the method according to the invention,

FIG. 4 illustrates another exemplary embodiment of the method according to the invention.

DESCRIPTION OF THE EMBODIMENTS

An embodiment of the vehicle according to the invention will now be described with reference to FIG. 1. The invention is suitable for installation in a thermal vehicle 1 or a hybrid vehicle comprising a thermal engine M. The vehicle 1 also comprises an electrical network 10, a catalytic converter 20, a battery 30, an electric machine 40 and an electronic control unit 50. The thermal engine M is, for example, is controlled by an engine control computer (not shown in the figures) which is also installed in the vehicle 1.

The electrical network 10 supplies the equipment of the vehicle 1 with electrical energy. To do this, the electrical network 10 comprises at least one electrical line installed in the vehicle 1 and electrically connected to the equipment to be powered.

The catalytic converter 20 is, for example, positioned at the output of the thermal engine M, and serves to depollute the exhaust gases emitted by the thermal engine M before the exhaust gases are emitted outside the vehicle 1. In the case of a thermal engine M running on diesel, for example, the catalytic converter 20 converts the carbon monoxide and hydrocarbons in the exhaust gases into carbon dioxide and water. In the case of a thermal engine M running on petrol, the catalytic converter 20 converts the carbon monoxide and nitrogen dioxide in the exhaust gases into carbon dioxide.

A high temperature in the catalytic converter 20 accelerates the chemical reactions that occur in the catalytic converter 20 in order to quickly and effectively depollute the exhaust gases from the thermal engine M. To do this, the catalytic converter 20 comprises an electric heating device 21 to heat up the inside of the catalytic converter 20. For this reason, this type of catalytic converter 20 can also be referred to by a person skilled in the art as an electrically heated catalyst.

The heating device 21 comprises, in particular, a heating resistor.

In order to avoid 24-volt or 48-volt electronics, the invention proposes the use of an electric machine 40 capable of supplying a voltage of 24 volts or 48 volts.

As shown in FIG. 2, the electric machine 40 is coupled, on the one hand, to a first switch 60 and, on the other hand, to a second switch 70 for this purpose. The first switch 60 is also coupled to the heating device 21, which is itself coupled to the catalytic converter 20 (not shown in FIG. 2).

Depending on a determined strategy, the first switch 60 is capable of being either in a closed position, enabling electrical energy to flow to the heating device 21 in order to heat up the catalytic converter 20, or in an open position, enabling the heating device 21 to be electrically isolated from the remainder of the electrical circuit 10.

The second switch 70 is also coupled to a DC/DC voltage converter 80. Depending on a determined strategy, the second switch 70 is capable of being either in a closed position, enabling the flow of electrical energy, or in an open position, enabling the electrical isolation of the remainder of the electrical circuit, i.e. the heating device 21 as well as the electric machine 40.

In a first exemplary embodiment, the DC/DC converter 80 is capable of converting the voltage from a value in the order of 24 volts or 48 volts delivered by the electric machine 40 to a voltage compatible with the voltage admissible by the battery 30, for example 12 volts. In this example, the DC/DC converter 80 is a one-way step-down voltage converter.

In a second exemplary embodiment, the DC/DC converter 80 is suitable for converting the voltage originating from the electric battery 30 into a voltage compatible with the heating device 21, i.e. 24 volts or 48 volts, and, on the other hand, is suitable for converting the voltage from a value in the order of 24 volts or 48 volts, delivered by the electric machine 40, into a voltage compatible with the voltage admissible by the battery 30, e.g. 12 volts. In this exemplary embodiment, the DC/DC converter 80 is referred to as a two-way converter. As shown in FIG. 2, the battery 30 is a 12-volt battery and is suitable for being coupled to the on-board network of the vehicle 1.

Thanks to the device according to the invention, there is therefore no need for vehicle electronics 1 compatible with the voltage of the electric machine 40.

The method according to the invention for controlling the heating device 21 will now be presented.

FIG. 3 shows a first embodiment of the method according to the invention corresponding to the use of a one-way DC/DC converter 80.

Said method comprises a first step e1, during which the heating device 21 is in a quiescent state, i.e. it is not activated to heat up the catalytic converter 20; the first switch 60 is in an open state, i.e. the heating device 21 is electrically isolated from the remainder of the electrical circuit 10 of the vehicle 1.

During a second step e2, the method according to the invention detects the need to activate the heating resistor 21 of the catalytic converter 20 in order to heat up the catalytic converter 20. This step can be carried out using an electronic structure in the form of an electronic computer suitable for recording the temperature of the catalytic converter 20 and/or controlling the heating device 21 and the electric machine 40.

If a need to activate the catalytic converter 20 is detected, the method according to the invention proposes to proceed to a third step e3. If no need to heat up the catalytic converter 20 is detected, the method loops to the second step e2.

An assessment is carried out in the third step e3 to determine the amount of electrical power required to heat up the catalytic converter 20, i.e. the electrical energy or electrical power required to raise the temperature of the catalytic converter 20 to a threshold temperature referred to as Tthreshold rendering the catalytic converter effective in depolluting the gases. Analyses of the measured parameters are simple for a person skilled in the art and will not be explained here. The effective temperature of the catalytic converter 20, for example, and/or the engine speed, and/or the gas flows can be measured in order to estimate the electrical power required to heat up the catalytic converter 20 as quickly as possible, depending on e.g. manufacturing data stored in a memory (not shown here). In addition, during the same third step e3, the state of charge of the battery 30 is also analyzed by the electronic computer.

The method according to the invention astutely proposes to take into account the state of charge of the battery 30 in order to power or not power the heating device 21. Thus, if the state of charge of the battery 30 is low, i.e. its charge level is less than a charge level value Nthresholdcharge, the method proposes to proceed to the fourth step e4. If the state of charge of the battery 30 is greater than the charge level Nthresholdcharge, the method according to the invention proposes to proceed to a fifth step e5.

If the state of charge of the battery 30 is low, the method according to the invention consists, during the fourth step e4, in switching the second switch 70 to an open state in order to isolate the heating device 21 and the electric machine 40 from the remainder of the electrical circuit 10 of the vehicle 1. During this fourth step e4, the first switch 60 is also switched to a closed state in order to couple the heating device 21 and therefore the catalytic converter 20 to the electric machine 40. It is then proposed to proceed to a sixth step e6.

During the sixth step e6, the electric machine 40 is controlled in order to generate the electrical power required by the heating device 21 to heat up the catalytic converter 20. The electric machine 40 can astutely generate a variable electrical voltage enabling real-time control of the temperature of the catalytic converter 20. This control of the electrical voltage of the electric machine 40 depending on the electrical power required by the catalytic converter 20 can be implemented by the electronic computer.

The temperature of the catalytic converter 20 is then recorded and analyzed in a seventh step e7, and the electric machine 40 is controlled to provide the necessary power until the catalytic converter 20 reaches its threshold temperature.

If the threshold temperature of the catalytic converter 20 is reached, the method according to the invention comprises an eighth step e8 consisting in deactivating the heating of the catalytic converter 20 by switching the first switch 60 to an open state.

By means of the invention, it is thus possible to control the heating of the catalytic converter 20 without having complex electronics and, above all, in a manner compatible with an electrical voltage equal to 24 volts or 48 volts. By means of the method according to the invention, it is also possible to heat up the catalytic converter 20 using the electric machine 40 without generating electrical or electromagnetic interference over the remainder of the electric network 10, thanks to the presence of the second switch 70 and its open state during the heating of the catalytic converter 20.

As mentioned earlier, if the state of charge of the battery 30 is higher than the charge level Nthresholdcharge, the method according to the invention proposes to proceed to a fifth step e5. During this fifth step e5, the method astutely proposes to switch the second switch 70 and the first switch 60 to a closed state in order to couple the heating device 21 to the DC/DC converter 80 and also to the DC machine 40.

During the fifth step e5, the DC/DC converter 80 and the electric machine 40 are also controlled to jointly generate the electrical power required by the heating device 21 to heat up the catalytic converter 20 to heat up. This function is performed, for example, by an electronic computer.

During the ninth step e9, the temperature of the catalytic converter 20 is then recorded and analyzed, and the DC/DC converter 80 and the electric machine 40 are controlled to provide the necessary power until the catalytic converter 20 reaches its threshold temperature.

If the threshold temperature of the catalytic converter 20 is reached, the method according to the invention comprises a tenth step e10 consisting in deactivating the heating of the catalytic converter 20 by switching the second switch 70 to an open state and alternately by switching the first switch 60 to an open state. The electric machine 40 and the DC/DC converter 80 are obviously controlled to no longer supply electrical energy to the heating device 21.

FIG. 4 shows a second embodiment of the method according to the invention corresponding to the use of a two-way DC/DC converter 80.

Said method comprises a first step e1, during which the heating device 21 is in a quiescent state, i.e. it is not activated to heat up the catalytic converter 20; the first switch 60 is in an open state, i.e. the heating device 21 is electrically isolated from the remainder of the electrical circuit 10 of the vehicle 1.

During a second step e2, the method according to the invention detects the need to activate the heating resistor 21 of the catalytic converter 20 in order to heat up the catalytic converter 20. This step can be carried out using an electronic structure in the form of an electronic computer suitable for recording the temperature of the catalytic converter 20 and/or controlling the heating device 21 and the electric machine 40.

If a need to activate the catalytic converter 20 is detected, the method according to the invention proposes to proceed to a third step e3. If no need to heat up the catalytic converter 20 is detected, the method loops to the second step e2.

An assessment is carried out in the third step e3 to determine the amount of electrical power required to heat up the catalytic converter 20, i.e. the electrical energy or electrical power required to raise the temperature of the catalytic converter 20 to a threshold temperature referred to as Tthreshold rendering the catalytic converter effective in depolluting the gases. Analyses of the measured parameters are simple for a person skilled in the art and will not be explained here. The effective temperature of the catalytic converter 20, for example, and/or the engine speed, and/or the gas flows can be measured in order to estimate the electrical power required to heat up the catalytic converter 20 as quickly as possible, depending on e.g. manufacturing data stored in a memory (not shown here). In addition, during the same third step e3, the state of charge of the battery 30 is also analyzed by the electronic computer.

The method according to the invention astutely proposes to take into account the state of charge of the battery 30 in order to power or not power the heating device 21. Thus, if the state of charge of the battery 30 is low, i.e. its charge level is less than a charge level value Nthresholdcharge, the method proposes to proceed to the thirtieth step e30. If the state of charge of the battery 30 is greater than the charge level Nthresholdcharge, the method according to the invention proposes to proceed to a fifth step e5.

If the state of charge of the battery 30 is low, the method according to the invention consists, during the thirtieth step e30, in choosing either to heat the heating device 21 by means of the electric machine 40, indicated simply by the transition to a fourth step e4, or to use the electrical energy of the electric machine 40 to supply electrical energy to heat up the heating device 21 and to recharge the battery 30, indicated by the transition to a thirty-first step e31. In a case such as the latter, the DC/DC converter will be actuated to ensure that electrical energy is delivered to battery 30.

The fourth step e4 consists in switching the second switch 70 to an open state in order to isolate the heating device 21 and the electric machine 40 from the remainder of the electrical circuit 10 of the vehicle 1. During this fourth step e4, the first switch 60 is also switched to a closed state in order to couple the heating device 21 and therefore the catalytic converter 20 to the electric machine 40. It is then proposed to proceed to a sixth step e6.

During the sixth step e6, the electric machine 40 is controlled in order to generate the electrical power required by the heating device 21 to heat up the catalytic converter 20. The electric machine 40 can astutely generate a variable electrical voltage enabling real-time control of the temperature of the catalytic converter 20. This control of the electrical voltage of the electric machine 40 depending on the electrical power required by the catalytic converter 20 can be implemented by the electronic computer.

The temperature of the catalytic converter 20 is then recorded and analyzed in a seventh step e7, and the electric machine 40 is controlled to provide the necessary power until the catalytic converter 20 reaches its threshold temperature.

If the threshold temperature of the catalytic converter 20 is reached, the method according to the invention comprises an eighth step e8 consisting in deactivating the heating of the catalytic converter 20 by switching the first switch 60 to an open state.

By means of the invention, it is thus possible to control the heating of the catalytic converter 20 without having complex electronics and, above all, in a manner compatible with an electrical voltage equal to 24 volts or 48 volts. By means of the method according to the invention, it is also possible to heat up the catalytic converter 20 using the electric machine 40 without generating electrical or electromagnetic interference over the remainder of the electrical network 10, thanks to the presence of the second switch 70 and its open state during the heating of the catalytic converter 20.

The thirty-first step e31 comprises switching the second switch 70 and the first switch 60 to a closed state in order to couple the heating device 21 and therefore the catalytic converter 20 to the electric machine 40. It is then proposed to proceed to a thirty-second step e32.

During the thirty-second step e32, the electric machine 40 is controlled in order to generate the electrical power required by both the heating device 21 to heat up the catalytic converter 20 and by the battery 30 to recharge it.

In a thirty-third step e33, the temperature of the catalytic converter 20 is then recorded and analyzed and the electric machine 40 is controlled to provide the necessary power until the catalytic converter 20 reaches its threshold temperature.

If the threshold temperature of the catalytic converter 20 is reached, the method according to the invention comprises a thirty-fourth step e34 consisting in deactivating the heating of the catalytic converter 20 by switching the first switch 60 to an open state.

The method astutely proposes a thirty-fifth step e35 consisting in recording the charge level of the battery 30. If the charge level is reached, the method according to the invention then proposes to proceed to a thirty-sixth step e36. If not, the method proposes to continue charging the battery 30 by means of the electric machine 40.

If the state of charge of the battery 30 is reached, the method proposes to deactivate the electric machine 40 during the thirty-sixth step e36, and also, for example, to position the second switch 70 in an open state.

By means of the invention, it is thus possible to control the heating of the catalytic converter 20 without having complex electronics and, above all, in a manner compatible with an electrical voltage equal to 24 volts or 48 volts. By means of the method according to the invention, it is also possible to heat up the catalytic converter 20 using the electric machine 40 without generating electrical or electromagnetic interference over the remainder of the electric network 10, thanks to the presence of the second switch 70 and its open state during the heating of the catalytic converter 20. It is also possible to charge the battery 30 while heating up the catalytic converter 20.

As mentioned earlier, if the state of charge of the battery 30 is higher than the charge level Nthresholdcharge, the method according to the invention proposes to proceed to a fifth step e5. During this fifth step e5, the method according to the invention proposes to record the amount of electrical power required to heat up the catalytic converter 20, i.e. the electrical energy or electrical power required by the heating device 21 to raise the temperature of the catalytic converter 20 to a threshold temperature referred to as Tthreshold rendering the catalytic converter efficient for gas pollution. Analyses of the measured parameters are simple for a person skilled in the art and will not be explained here. The effective temperature of the catalytic converter 20, for example, and/or the engine speed, and/or the gas flows, and also the state of charge of the battery 30 can be measured to estimate, depending, for example, on manufacturing data stored in a memory (not shown here), the electrical power required to heat up the catalytic converter 20 as quickly as possible. These calculations can be performed by the electronic computer.

If the state of charge of the battery 30 is sufficient in itself to raise the temperature of the catalytic converter 20 to a threshold temperature, the method proposes to proceed to a ninth step e9.

If the electrical power required by the heating device 21 to heat up the catalytic converter 20 is only generatable by the electric machine 40, the method proposes to proceed to a tenth step e10.

If the state of charge of the battery 30 is not sufficient in itself to raise the temperature of the catalytic converter 20 to a threshold temperature, and if it is necessary to add the generatable electrical power of the electric machine 40 to it, the method proposes to proceed to an eleventh step e11.

In the ninth step e9, the method proposes to switch the second switch 70 to a closed state and to switch the first switch 60 to an open state in order to isolate the electric machine 40. Only the battery 30, through the DC/DC converter 80, will thus be astutely used to supply the heating device 21 and thus raise the temperature of the catalytic converter 20 to the threshold temperature. The DC/DC converter 80 is used, for example, in buck mode. The method then proposes to proceed to a fourth step e12).

During the twelfth step e12, the DC/DC converter 80 is controlled in order to generate the electrical power required by the heating device 21 to heat up the catalytic converter 20. This command can be performed by the electronic computer 50.

The temperature of the catalytic converter 20 is then recorded and analyzed in a thirteenth step e13, and the DC/DC converter 80 is controlled to provide the power required by the heating device 21 to enable the catalytic converter 20 to reach its threshold temperature. If the threshold temperature of the catalytic converter 20 is reached, the method according to the invention comprises a fourteenth step e14 consisting in deactivating the heating of the catalytic converter 20 by switching the second switch 70 to an open state and/or by stopping the control of the DC/DC converter 80.

By means of the invention, it is thus possible to control the heating of the catalytic converter 20 without using the electric machine 40.

In the tenth step e10, the method proposes to switch the second switch 70 to an open state in order to isolate the heating device 21 and the electric machine 40 from the remainder of the electrical circuit 10 of the vehicle 1. During this fourth step e4, the first switch 60 is switched to a closed state in order to couple the catalytic converter 20 to the electric machine 40. It is then proposed to proceed to a fifteenth step e15.

During the fifteenth step e15, the electric machine 40 is controlled in order to generate the electrical power required by heating device 21 to heat up the catalytic converter 20. The electric machine 40 can astutely generate a variable electrical voltage enabling real-time control of the temperature of the catalytic converter 20. This control of the electrical voltage of the electric machine 40 depending on the electrical power required by the catalytic converter 20 can be implemented by the electronic computer.

In a sixteenth step e16, the temperature of the catalytic converter 20 is then recorded and analyzed, and the electric machine 40 is controlled to provide the necessary power until the catalytic converter 20 reaches its threshold temperature.

If the threshold temperature of the catalytic converter 20 is reached, the method according to the invention comprises a seventeenth step e17 consisting in deactivating the heating of the catalytic converter 20 by switching the first switch 60 to an open state.

By means of the invention, it is thus possible to control the heating of the catalytic converter 20 without having complex electronics and, above all, in a manner compatible with an electrical voltage equal to 24 volts or 48 volts. By means of the method according to the invention, it is also possible to heat up the catalytic converter 20 using the electric machine 40 without generating electrical or electromagnetic interference over the remainder of the electric network 10, thanks to the presence of the second switch 70 and its open state during the heating of the catalytic converter 20.

In the eleventh step e11, the method proposes to switch the second switch 70 and the first switch 60 to a closed state so that the electric machine 40 and the battery 30, through the DC/DC converter 80, provide the electrical power required by the heating device 21 to enable the catalytic converter 20 to reach the desired temperature. It is then proposed to proceed to an eighteenth step e18.

During the eighteenth step e18, both the electric machine 40 and the DC/DC converter 80 are controlled in order to generate the electrical power required by the heating device 21 to heat up the catalytic converter 20. The electric machine 40 can astutely generate a variable electrical voltage enabling real-time control of the temperature of the catalytic converter 20. This control of the electrical voltage of the electric machine 40 depending on the electrical power required by the catalytic converter 20 can be implemented by the electronic computer.

The temperature of the catalytic converter 20 is then recorded and analyzed in a nineteenth step e19, and the electric machine 40 and/or the DC/DC converter 80 is/are controlled to provide the necessary power until the catalytic converter 20 reaches its threshold temperature.

If the threshold temperature of the catalytic converter 20 is reached, the method according to the invention comprises a twentieth step e20 consisting in deactivating the catalytic converter heating 20 by switching the first switch 60 and the second switch 70 to an open state.

In one variant embodiment of the invention (not shown), the method can astutely combine the steps relating to the heating of the catalytic converter 20 with steps relating to the charging of the battery 30, simultaneously enabling the charging of the battery 30 and the heating of the catalytic converter 20 by the electric machine 40. In such a case, the DC/DC converter 80 is a two-way converter.

Thanks to the invention it is possible to perform a rapid heating of the catalytic converter without having vehicle electronics compatible with a voltage of 24 volts or 48 volts.

Claims

1. A method for powering a heating device (21) for a motor vehicle (1) having a thermal engine (M), said vehicle (1) comprising an electrical network (10), a catalytic converter (20) capable of depolluting the exhaust gases emitted by the engine (M) and comprising an electric heating device (21), a battery (30), a DC/DC converter (80), an electric machine (40), a first switch (60) suitable for switching between a closed-circuit state and an open-circuit state, and a second circuit switch (70) state suitable for switching between a closed-circuit state and an open-circuit state,

said method comprising the following steps:

el) checking an open circuit condition of the first switch (60) corresponding to a catalytic converter (20) not electrically heated,

e2) detecting a need to activate the electric heating device (21) of the catalytic converter (20),

e3) determining the electrical power required to reach a threshold temperature (Tthreshold) of the catalytic converter (20) and determining the electrical power of the battery (30), if the power of the battery (30) is below a charge level Nthresholdcharge, then proceeding to a fourth step e4); if the battery power (30) is above a charge level Nthresholdcharge, then proceeding to a fifth step e5);

e4) checking that the second switch (70) is in an open-circuit state and then positioning the first switch (60) in the closed-circuit state in order to couple the electric machine (40) to the heating device (21),

e6) controlling the electric machine (40) in order to generate the electrical power to heat up the catalytic converter (20),

e7) checking the temperature of the catalytic converter (20),

e8) switching off the heating device (21) and positioning the second switch (70) in an open-circuit state when the temperature of catalytic converter (20) is at least equal to the threshold temperature (Tthreshold),

e5) comparing the quantity of electrical power required to heat up the catalytic converter (20) to reach the threshold temperature (Tthreshold) with the electrical power deliverable by the battery

(30) and by the electric machine (40), if the electrical power deliverable by the battery (30) is sufficient, then proceeding to a ninth step e9), if the electrical power deliverable by the electric machine (40) is sufficient, then proceeding to a tenth step e10), if the electrical power required to heat up the catalytic converter (20) to reach the threshold temperature (Tthreshold) is greater than the electrical power deliverable by the electric machine (40) and the electrical power deliverable by the battery (30), then proceeding to an eleventh step e11), e9) switching the second switch (70) to a closed state and switching the first switch (60) to an open state,

e12) controlling the DC/DC converter (80) in order to generate the electrical power required by the heating device (21) to heat up the catalytic converter (20),

e10) switching the second switch (70) to an open state of and switching the first switch (60) to a closed state,

e15) controlling the electric machine (40) in order to generate the electrical power required by the heating device (21) to heat up the catalytic converter 20,

e11) controlling the second switch (70) to a closed state and switching the first switch (60) to a closed state,

e18) controlling the electric machine (40) and the battery (30) in order to generate the electrical power required by the heating device (21) to heat up the catalytic converter (20).