Method for increasing the temperature of an exhaust gas catalyst

Abstract

One aspect of the invention relates to a method 100 for increasing the temperature of an exhaust gas catalyst for a hybrid motor vehicle, the vehicle comprising an onboard network supplied with power by an auxiliary battery and a DC-to-DC converter, the method 100 comprising the steps, carried out by a computer 12 of the vehicle, of: - detecting 101 a request to start a combustion engine; - if the temperature of the catalyst is below an operating threshold temperature, electrically connecting 102 an electrical heating device for electrically heating the catalyst, the electrical heating device belonging to the onboard network; - electrically disconnecting 104 at least one electrical component from the onboard network; - when the temperature of the catalyst is equal to or higher than the operating threshold temperature, starting 105 the combustion engine; - electrically disconnecting 106 the electrical heating device from the catalyst.

Description

DESCRIPTION TITLE OF THE INVENTION: METHOD FOR INCREASING THE TEMPERATURE OF AN EXHAUST GAS CATALYST

[0001] The present invention claims priority from French application No. 2307634 filed on 17.07.2023, the content of which (text, drawings and claims) is incorporated herein by reference.

[0002] One aspect of the invention relates to a method for increasing the temperature of an exhaust gas catalyst for a motor vehicle equipped with an internal combustion engine. This aspect of the invention finds a particularly interesting application in hybrid vehicles equipped with an exhaust gas catalyst incorporating an electric heating device.

[0003] In motor vehicles equipped with an internal combustion engine, exhaust gas treatment is a major issue. The purpose of this treatment is to reduce the emissions of various pollutants resulting from the operation of the internal combustion engine.

[0004] Typically, in a motor vehicle equipped with an internal combustion engine, exhaust gas treatment is carried out by a catalyst whose role is to transform the most toxic components of the exhaust gases into less toxic elements. The chemical reactions that occur within the catalyst result in pollution control that is more or less effective depending on the temperature of the catalyst.

[0005] In order to increase the speed at which the engine and therefore the catalyst heat up, it is known from document US-B2-7367179 to reduce the efficiency of the internal combustion engine by applying an additional load, for example, two glow plugs.

[0006] Although this solution allows the catalyst temperature to be increased more quickly, it is still not satisfactory.

[0007] In order to optimize the depollution of exhaust gases, it is also known to integrate an electric catalyst heating device into the vehicle.

[0008] This heating device aims to allow the catalyst to reach operating temperature quickly before starting the internal combustion engine.

[0009] In order to increase the catalyst temperature in a short time, the electric heating device consumes a very high electrical power (a few kW) which is supplied entirely or partially by a 12V on-board network. It is known to oversize the 12V service battery as well as the DC / DC converter of the vehicle to allow the supply of such electrical power.

[0010] This oversizing results in significant bulk and high costs.

[0011] The aim of the invention is in particular to propose a method for increasing the temperature of an exhaust gas catalyst making it possible to avoid such oversizing.

[0012] In this context, the invention thus relates, in its broadest sense, to a method for increasing the temperature of an exhaust gas catalyst for a hybrid motor vehicle, the hybrid motor vehicle comprising an on-board network electrically powered by a service battery and a DC / DC converter, the method comprising the steps, executed by a computer of the vehicle, of: Detect a request to start a vehicle's thermal engine; If the catalyst temperature is below an operating threshold temperature, electrically connect an electric catalyst heating device, the electric heating device belonging to the on-board network; Electrically disconnect at least one electrical component from the on-board network, said electrical component being different from the electric heating device; When the catalyst temperature is equal to or higher than the operating threshold temperature, start the heat engine; Electrically disconnect the electric heating device from the catalyst.

[0013] For the remainder of the description, the term "connect" means that the electric heating device or an electrical component is passing through an electric current supplied by the service battery as well as by the DC / DC converter and is in operation. Conversely, the term "disconnect" means that the electric heating device or an electrical component is not passing through an electric current and is not in operation.

[0014] Since at least one electrical component is disconnected when powering the electric heating device, the overall electrical consumption of the on-board network is maintained at an acceptable level without requiring oversizing the service battery, or even the DC / DC converter.

[0015] This electrical component can, for example, be formed by a heating device for a vehicle seat.

[0016] In addition to the characteristics which have just been mentioned in the preceding paragraph, the method according to the invention may have one or more additional characteristics among the following, considered individually or according to all technically possible combinations.

[0017] According to a non-limiting aspect of the invention, successively to the step of electrically disconnecting the electric heating device from the catalyst, the method comprises a step of electrically connecting at least one electrical component previously electrically disconnected.

[0018] According to a non-limiting aspect of the invention, successively to the step of electrically connecting the electric heating device of the catalyst, the method comprises a step of determining the voltage at the terminals of the service battery, if the determined voltage is lower than a threshold voltage, electrical components of the on-board network are electrically disconnected one after the other until said determined voltage is greater than or equal to said threshold voltage.

[0019] According to a non-limiting aspect of the invention, the threshold voltage is between 12V and 13V.

[0020] According to a non-limiting aspect of the invention, the operating threshold temperature is between 150 and 250 degrees Celsius.

[0021] According to a non-limiting aspect of the invention, the electrically disconnected electrical component contributes to the comfort of the vehicle passengers.

[0022] According to a non-limiting aspect of the invention, the electrical component is formed by a device for heating a seat of the vehicle, a device for heating the steering wheel of the vehicle, an electric air heater for the passenger compartment of the vehicle, a passenger compartment air blower of the vehicle, a motor-fan unit of the vehicle or a heated windscreen of the vehicle.

[0023] According to a non-limiting aspect of the invention, an electrical component is: Electrically disconnected by opening a power supply relay of the electrical component, and Electrically connected by closing the electrical component's power supply relay.

[0024] According to a non-limiting aspect of the invention, the electric heating device of the catalyst is: Electrically connected by closing a power supply relay of the electric heating device, and Electrically disconnected by opening the power supply relay of the electric heating device.

[0025] Another aspect of the invention relates to a hybrid motor vehicle computer, the computer being remarkable in that it is constructed and arranged to execute the steps of the method according to any one of the aforementioned aspects of the invention.

[0026] The invention and its various applications will be better understood by reading the following description and examining the accompanying figures.

[0027] [Fig. 1] schematically illustrates a hybrid automobile vehicle comprising a computer according to one aspect of the invention.

[0028] [Fig. 2] schematically illustrates a method of increasing the temperature of an exhaust gas catalyst for a hybrid motor vehicle according to one aspect of the invention.

[0029] [Fig. 3] schematically illustrates a method of increasing the temperature of an exhaust gas catalyst for a hybrid motor vehicle according to another aspect of the invention.

[0030] The figures are presented for information purposes only and in no way limit the invention.

[0031] Unless otherwise specified, the same element appearing in different figures has a single reference.

[0032] Figure 1 illustrates a hybrid automobile vehicle 1. The vehicle 1 comprises an on-board network 2 electrically powered by a service battery 3 and a DC / DC converter 4.

[0033] The DC / DC converter 4 is a direct-direct current converter arranged to convert a high voltage current, for example 400V, from a traction battery 5 of the vehicle 1 into a service current, for example 12V, and to electrically supply the service battery 3 and the on-board network 2 of the vehicle. Such a direct-direct current converter is commonly referred to by those skilled in the art as a DC / DC converter for “Direct Current / Direct Current” in English.

[0034] The on-board network 2 comprises an electric heating device 6 for a catalyst 7 of the exhaust gases contained in the vehicle 1. The electric heating device 6 can be electrically connected and disconnected from the on-board network 2 by a relay 8.

[0035] The on-board network 2 further comprises electrical components formed for example by a vehicle seat heating device 9i, a vehicle steering wheel heating device 92, an electric passenger compartment air heater 9s, a passenger compartment air blower 94, a motor-fan unit 9s or a heated windscreen 9e. Each electrical component can be electrically connected and disconnected from the on-board network 2 by a relay 10.

[0036] The vehicle 1 further comprises a heat engine 11 and a computer 12 which may, for example, be formed by a vehicle control unit (better known by the acronym VCU for Vehicle Control Unit in English).

[0037] The computer 12 is constructed and arranged to execute the steps of the method 100 for increasing the temperature of an exhaust gas catalyst for a hybrid vehicle according to the invention.

[0038] The method 100 comprises a step 101 of detecting a request to start the thermal engine 11 of the vehicle 1.

[0039] This detection can be performed by receiving a signal reflecting a start request that is expected to occur soon. In a non-limiting manner, this signal can be a command signal for opening an opening of the vehicle generated by pressing a remote control or by pressing a button on a mobile application. This signal can also be generated by pressing a start button on the vehicle.

[0040] Following this step of detecting 101 a request to start the heat engine 11, if the temperature of the catalyst 7 is lower than an operating threshold temperature, the method 100 comprises a step of electrically connecting 102 the electric heating device 6 of the catalyst 7. The temperature can be measured by means of a temperature sensor (not shown) arranged near the electric heating device 6 and then transmitted to the computer 12.

[0041] According to a non-limiting implementation, the operating threshold temperature is between 150 and 250 degrees Celsius, typically 200 degrees Celsius.

[0042] The electric heating device 6 of the catalyst 7 is electrically connected to the on-board network 2 by closing the electrical supply relay 8 of the electric heating device 6. As soon as this relay 8 is closed, the electric heating device 6 is electrically supplied by the service battery 3 and the DC / DC converter 4 of the vehicle 1.

[0043] Following the step of electrically connecting 102 the electric heating device 6 of the catalyst 7, the method 100 comprises a step of determine 103 the voltage at the terminals of the service battery 3 electrically supplying the on-board network 2.

[0044] The voltage across the service battery 3 can be measured by a battery management system (not shown) (better known by the acronym BMS for Battery Management System in English). This voltage can then be transmitted to the computer 12.

[0045] If the determined voltage is lower than a threshold voltage, the method 100 comprises a step of electrically disconnecting 104 the electrical components 9i, 92, 9s, 94, 9s, 9e from the on-board network 2 one after the other until the determined voltage is greater than or equal to the threshold voltage.

[0046] In other words, the electrical components 9i, 92, 9s, 94, 9s, 9e are deactivated until the overall electrical load of the on-board network 2 can be supported by the service battery 3, while knowing that the electrical supply to the electric heating device 6 of the catalyst 7 is, for its part, maintained.

[0047] According to a non-limiting implementation, the threshold voltage is between 12V and 13V, typically 12.8V.

[0048] According to a non-limiting implementation, the electrically disconnected electrical component contributes to the comfort of the vehicle passengers. It can for example be formed by a heating device for a vehicle seat 9i, a heating device for the vehicle steering wheel 92, an electric air heater for the passenger compartment 9s, a passenger compartment air blower 94, a motor-fan unit 9s or a heated windshield 9e.

[0049] Each electrical component is electrically disconnected from the on-board network 2, and more particularly from the service battery 3, by opening a relay 10 for supplying electrical power to said electrical component. As soon as this relay 10 is open, the corresponding electrical component is electrically isolated from the on-board network 2 of the vehicle 1. It is therefore no longer electrically supplied by the service battery 3.

[0050] When the temperature of the catalyst 7 is equal to or greater than the operating threshold temperature, the method 100 comprises a step of starting 105 the heat engine 11.

[0051] As catalyst 7 has reached its operating temperature, it is effectively able to fully perform its exhaust gas treatment function.

[0052] When the heat engine 11 is started, the method 100 comprises a step 106 of electrically disconnecting the electric heating device 6 from the catalyst 7.

[0053] The electric heating device 6 of the catalyst 7 is electrically disconnected from the on-board network 2 by opening the electrical supply relay 8 of the electric heating device 6. As soon as this relay 8 is open, the electric heating device 6 is electrically isolated from the on-board network 2 and is no longer electrically supplied.

[0054] Subsequent to the step of electrically disconnecting 106 the electric heating device from the catalyst, the method 100 comprises a step of electrically connecting 107 the at least one electrical component previously electrically disconnected.

[0055] Each electrical component is electrically connected to the on-board network 2 by closing the electrical supply relay 10 of said electrical component. As soon as this relay 10 is closed, the corresponding electrical component is electrically connected to the on-board network 2.

[0056] Figure 3 illustrates a different implementation of a method 100 for increasing the temperature of the exhaust gas catalyst 7 for a hybrid vehicle 1 according to the invention.

[0057] The method 100 comprises a step 101 of detecting a request to start the thermal engine 11 of the vehicle 1.

[0058] Following this step of detecting 101 a request to start the thermal engine 11, if the temperature of the catalyst 7 is lower than an operating threshold temperature, the method 100 comprises a step of electrically connecting 102 the electric heating device 6 of the catalyst 7 to the on-board network 2.

[0059] The method 100 further comprises a step of electrically disconnecting 104 at least one of the electrical components 9i, 92, 9s, 94, 9s, 9e from the on-board network 2 of the vehicle 1.

[0060] According to this embodiment, the step 103 of determining the voltage across the terminals of the service battery 3 is not performed. In this case, at least one of the electrical components 9i, 92, 9s, 94, 9s, 9e of the on-board network 2 is electrically disconnected from the on-board network 2 following the step 102 of electrically connecting the electrical heating device 6 of the catalyst 7. The at least one electrical component to be electrically disconnected can be pre-recorded in the computer 12.

[0061] When the temperature of the catalyst 7 is equal to or greater than the operating threshold temperature, the method 100 comprises a step of starting 105 the heat engine 11, then a step of electrically disconnecting 106 the electric heating device 6 from the catalyst 7.

Claims

CLAIMS

1. Method (100) for increasing the temperature of a catalyst (7) of the exhaust gases for a hybrid motor vehicle (1), said vehicle (1) comprising an on-board network (2) electrically powered by a service battery (3) and a DC / DC converter (4), said method (100) comprising the steps, executed by a computer (12) of said vehicle (1), of: Detect (101) a request to start a thermal engine (11) of said vehicle (1); If the temperature of said catalyst (7) is lower than an operating threshold temperature, electrically connect (102) an electric heating device (6) of said catalyst (7), said electric heating device (6) belonging to said on-board network (2); Electrically disconnect (104) at least one electrical component (9i, 9 2>9s, 94, 95, 9e) of said on-board network (2), said electrical component (9i, 92, 9s, 94, 9s, 9s) being different from said electric heating device (6); When the temperature of said catalyst (7) is equal to or greater than the operating threshold temperature, start (105) said heat engine (11); Electrically disconnect (106) said electric heating device (6) from said catalyst (7).

2. Method (100) according to the preceding claim, characterized in that, successively to the step of electrically disconnecting (106) the electric heating device (6) from the catalyst (7), the method (100) comprises a step of electrically connecting (107) the at least one electrical component (9i, 92, 9s, 94, 9s, 9e) previously electrically disconnected. [Claim s] Method (100) according to any one of the preceding claims, characterized in that, successively to the step of electrically connecting (102) the electric heating device (6) of the catalyst (7), the method (100) comprises a step of determining (103) the voltage at the terminals of the service battery (3), if the determined voltage is lower than a threshold voltage, electrical components (9i, 92, 9s, 94, 9s, 9e) of the on-board network (2) are electrically disconnected one after the other until said determined voltage is higher than or equal to said threshold voltage.

4. Method (100) according to the preceding claim, characterized in that the threshold voltage is between 12V and 13V. [Claim s] Method (100) according to any one of the preceding claims, characterized in that the operating threshold temperature is between 150 and 250 degrees Celsius. [Claim s] Method (100) according to any one of the preceding claims, characterized in that the electrically disconnected electrical component (9i, 92, 9s, 94, 9s, 9e) contributes to the comfort of the passengers of the vehicle (1)-

7. Method (100) according to the preceding claim, characterized in that the electrical component is formed by a device for heating a seat (9i) of the vehicle (1), a device for heating the steering wheel (92) of said vehicle (1), an electric air heater for the passenger compartment (9s) of said vehicle (1), a passenger compartment air blower (94) of said vehicle (1), a motor-fan unit (9is) of said vehicle (1) or a heated windshield (9e) of said vehicle (1). [Claim s] Method (100) according to any one of the preceding claims, characterized in that an electrical component (9i, 92, 9s, 94, 9s, 9e) is: - Electrically disconnected by opening a relay (10) supplying power to said electrical component, and - Electrically connected by closing said relay (10) for supplying power to said electrical component.

9. Method (100) according to any one of the preceding claims, characterized in that the electrical heating device (6) of the catalyst (7) is: Electrically connected by closing a relay (8) supplying power to said electric heating device (6), and - Electrically disconnected by opening said relay (8) of electrical supply of said electric heating device (6).

10. Computer (12) of a hybrid motor vehicle (1), characterized in that it is constructed and arranged to carry out the steps of the method (100) according to any one of the preceding claims.

Images