Controlled catalytic converter heating
The rate at which a catalytic converter for an internal combustion engine heats up to its normal operating temperature range can be increased by applying an electrical load that is powered by the internal combustion engine. Applying the electrical load demands more power from the engine which therefore has to work harder to maintain a given engine speed. The internal combustion engine then generates more heat that can be used to reduce the time to bring the catalytic converter up to its working temperature. The electrical load can be a catalytic converter heater to further reduce the time to bring the catalytic converter up to its working temperature. The result is a reduction in emissions.
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1. Field
Example embodiments of the invention relate to controlling heating of a catalytic converter.
2. Related Art
A significant proportion of the emissions from a modern automotive internal combustion engine occurs during the first few minutes of the engine operation following a cold start. This is due to the catalytic converter not being able to function correctly until it achieves “light off”, that is until it has reached its working temperature.
A catalytic converter can be very effective at reducing unwanted exhaust emissions when it is operating at its working temperature. However, until a catalytic converter reaches its working temperature, it works inefficiently at best. As a result, untreated exhaust gas can exit the end of the exhaust, or tailpipe. In the first two to three minutes of warm-up following a cold start, about 60% to 80% of exhaust, or tailpipe, emissions occur.
The regulatory authorities are imposing ever more strict emission regulations. In order to provide an effective reduction in exhaust emissions, it is therefore desirable to cause the catalytic converter to get up to working temperature as quickly as possible.
Various approaches have been employed to reduce the time that it takes a catalytic converter to reach its working temperature. One approach is to moving the catalytic converters as close to the exhaust ports as possible. A further approach that has been suggested is to provide an exhaust gas combustion system. A further approach is to provide a mechanism to retain the heat in a catalytic converter between journeys. All of these approaches involve expensive modifications to an existing engine system and/or exhaust system and/or provide packaging challenges.
It has also been suggested to provide electrical and/or flame heaters for catalytic converters, although this has not been done in an integrated manner.
Other engine based approaches include providing precise fuelling control, providing controlled ignition retarding, providing secondary air injection, using high starting engine speed and providing changes to the catalyst physics. These approaches include various disadvantages including a less enjoyable driving experience (e.g. due to increased noise), reductions in performance, complexity, combustion stability and cost.
Accordingly, there is still a need for an improved solution to reduce the time taken for a catalytic converter to reach its working temperature.
SUMMARYAn example embodiment of the invention can provide a method of operating an engine system. The engine system can include an internal combustion engine that is operable to apply drive to a drive train, a catalytic converter through which exhaust gases from the internal combustion engine pass and a control system. The method can include the control system determining whether the internal combustion engine is in an operating phase in which the catalytic converter is not at its working temperature. In response to such a determination by the control system, the control system can activate an electrical load element that is powered by the internal combustion engine whereby an additional load is placed on the internal combustion engine.
By activating an electrical load element that is driven by the internal combustion engine, the internal combustion engine has to work harder to maintain a give engine speed and therefore generates more heat that can be used to reduce the time that it takes to bring the catalytic converter up to its working temperature. As a result, a reduction in emissions can be achieved.
In an example embodiment the electrical load is a catalytic converter heater. In this case, there is the added benefit that the catalytic converter heater is also working to increase the temperature of the catalytic converter, which has the effect of further reducing the time that it takes to bring the catalytic converter up to its working temperature and further reducing emissions.
An embodiment of the invention can provide an engine system. The engine system can include an internal combustion engine that is operable to apply drive to a drive train, a catalytic converter through which exhaust gases from the internal combustion engine pass and a control system. The control system can be operable to determine whether the internal combustion engine is in an operating phase in which the catalytic converter is not at its working temperature and, if so, to activate an electrical load element that is powered by the internal combustion engine, whereby an additional load is placed on the internal combustion engine.
A motor vehicle can be provided with such an engine system. The electrical load can be in the form of a catalytic converter heater. The operating phase operating phase of the internal combustion engine can be a start up phase.
The motor vehicle can be a hybrid vehicle that also includes at least one electric drive motor. The operating phase of the internal combustion engine can be one of a start up phase and an electrical drive phase.
Specific example embodiments of the present invention will now be described by way of example only with reference to the accompanying drawings.
An example embodiment of the invention seeks to increase the rate at which a catalytic converter heats up to its normal operating temperature range by applying an electrical load that is powered by an internal combustion engine during a start up phase. Applying the electrical load demands more power from the engine which therefore has to work harder to maintain a given engine speed. The internal combustion engine therefore generates more heat that can be used to reduce the time to bring the catalytic converter up to its working temperature. As a result, a reduction in emissions can be achieved.
Various approaches mentioned in the background above have been employed to reduce the light off time. However, the prior approaches all include disadvantages. An example embodiment of the invention can provide an improved engine system and method of operation thereof.
As shown in
A control system 26 includes an engine management controller 28 that is responsive to various sensors, including one or more lambda probes 30, one or more catalytic converter temperature sensors 32, and one or more ambient temperature sensors 34, one or more crankshaft sensors 36, etc. In an example embodiment, the control system is also operable to control the automatic transmission 20, braking systems (not shown in
The engine system 12 further includes a battery 40 that is used to provide electrical power electrical components of the engine system via a regulator 42. The battery is kept charged by means of a generator 44 that is driven by the internal combustion engine, for example via a drive belt or drive chain.
In this example embodiment of the invention, the catalytic converter is provided with a catalytic converter heater 45. In
The control system 26 can be responsive to sensors (not shown) to determine if the internal combustion engine is in an operating phase in which the catalytic converter is not at its working temperature. In such a case, the control system 26 can activate the catalytic converter heater 45 to heat the catalytic converter 25. The catalytic converter heater forms an electrical load element that is powered by the internal combustion engine via the generator 44, either directly, or for example via the regulator 42 as shown in
As a result of the additional electrical load caused by the catalytic converter heater 45, the time for heating up the catalytic converter is reduced by the dual effects of the direct heating effect of the catalytic converter heater 45 and the additional load that is placed on the internal combustion engine, whereby the heat output of the internal combustion engine is increased for a given engine speed compared to the situation where the additional electrical load is not applied.
The external load can be applied until the catalytic converter has reached a predetermined temperature, for example a minimum efficient operating temperature, for a predetermined time, or a combination thereof (for example, until it has reached the predetermined temperature or until a predetermined time has elapsed, which ever occurs first). As will be seen in
Where the additional electrical load is in the form of a catalytic converter heater, the time for heating up the catalytic converter is reduced by the dual effects of the catalytic converter heater and the additional load that is placed on the internal combustion engine, whereby the heat output of the internal combustion engine is increased for a given engine speed compared to the situation where the additional electrical load is not applied.
During operation of the engine system shown in
As shown in
In addition, and electric motor 64 and a generator 44 are provided. The internal combustion engine 14, the electric motor 64 and the generator 44 are coupled together via a power split device 66. The power split device 66 allows the vehicle to be powered by the electric motor 64 alone, the internal combustion engine 14 alone or by both together. The power split device 66 also allows internal combustion engine 14 to operate independently of the vehicle speed for charging batteries or providing power to the wheels 68 via the drive shafts 72 as needed. It also acts as a continuously variable transmission (CVT). The electric motor 64 can be coupled to the internal combustion engine 14 via the generator 44.
As mentioned, the control system 26 is responsive to various sensors (not shown). In an example embodiment, the control system is also operable to control the operation of the power split device and the generator and of the catalytic converter heater.
The vehicle further includes a battery 40 that is used to provide electrical power electrical components of the engine system via a regulator 42. The battery is kept charged by power supplied from the generator 44 that is driven by the internal combustion engine 14. Power for charging the battery 40 can also be provided through regenerative braking, solar power and other means.
In operation of the engine system of the vehicle shown in
As a result of the additional electrical load caused by the catalytic converter heater 45, the time for heating up the catalytic converter is reduced by the dual effects of the direct heating effect of the catalytic converter heater 45 and the additional load that is placed on the internal combustion engine, whereby the heat output of the internal combustion engine is increased for a given engine speed compared to the situation where the additional electrical load is not applied.
As described above, with reference to
Thus there has been described a method and apparatus that can increase the rate at which a catalytic converter of an internal combustion engine heats up to its normal operating temperature range by applying an electrical load that is powered by the internal combustion engine during a start up phase. Applying the electrical load demands more power from the internal combustion engine which therefore has to work harder to maintain a given engine speed. The internal combustion engine therefore generates more heat that can be used to reduce the time to bring the catalytic converter up to its working temperature. As a result, a reduction in emissions can be achieved.
Although the embodiments above have been described in considerable detail, numerous variations and modifications will become apparent to those skilled in the art once the above disclosure is fully appreciated. It is intended that the following claims be interpreted to embrace all such variations and modifications as well as their equivalents.
Claims
1. A method of operating an engine system, the engine system including an internal combustion engine that is operable to apply drive to a drive train, a catalytic converter through which exhaust gases from the internal combustion engine pass and a control system, the method comprising:
- determining, by the control system, that the internal combustion engine is in an operating phase in which the catalytic converter is not at its working temperature; and
- activating, by the control system, an electrical load element that is powered by the internal combustion engine so that an additional load is placed on the internal combustion engine in response to said determining by the control system.
2. The method of claim 1, wherein the engine system comprises a generator driven by the internal combustion engine, the electrical load being powered by the internal combustion engine via the generator.
3. The method of claim 1, wherein the engine system includes a battery, and wherein the electrical load draws a current in excess of that available from the battery.
4. The method of claim 1, wherein the electrical load is a catalytic converter heater.
5. The method of claim 4, wherein the catalytic converter heater is integral to the catalytic converter.
6. The method of claim 4, wherein the catalytic converter heater is external to the catalytic converter.
7. The method of claim 1, wherein the additional load is applied until the catalytic converter reaches a predetermined temperature.
8. The method of claim 1, wherein the additional load is applied until the catalytic converter reaches a predetermined temperature or until a predetermined time has elapsed, whichever occurs first.
9. The method of claim 1, wherein the additional load is applied for a predetermined time.
10. The method of claim 1, wherein the operating phase of the internal combustion engine is a start up phase.
11. An engine system comprising:
- an internal combustion engine that is operable to apply drive to a drive train;
- a catalytic converter through which exhaust gases from the internal combustion engine pass; and
- a control system operable to determine that the internal combustion engine is in an operating phase in which the catalytic converter is not at its working temperature, and then to activate an electrical load element that is powered by the internal combustion engineso that an additional load is placed on the internal combustion engine in response to the determination by the control system.
12. The engine system of claim 11, comprising a generator driven by the internal combustion engine, the electrical load being powered by the internal combustion engine via the generator.
13. The engine system of claim 11, wherein the engine system includes a battery, and wherein the electrical load draws a current in excess of that available from the battery.
14. The engine system of claim 11, wherein the electrical load element is in the form of a catalytic converter heater.
15. The engine system of claim 14, wherein the catalytic converter heater is integral to the catalytic converter.
16. The engine system of claim 14, wherein the catalytic converter heater is external to the catalytic converter.
17. The engine system of claim 11, wherein the control system is operable to apply the additional load until the catalytic converter reaches a predetermined temperature.
18. The engine system of claim 11, wherein the control system is operable to apply the additional load until the catalytic converter reaches a predetermined temperature or until a predetermined time has elapsed, whichever occurs first.
19. The engine system of claim 11, wherein the control system is operable to apply the additional load for a predetermined time.
20. The engine system of claim 11, wherein the operating phase of the internal combustion engine is a start up phase.
21. A motor vehicle comprising an engine system, the engine system comprising:
- an internal combustion engine that is operable to apply drive to a drive train;
- a catalytic converter through which exhaust gases from the internal combustion engine pass; and
- a control system operable to determine that the internal combustion engine is in an operating phase in which the catalytic converter is not at its working temperature, and then to activate an electrical load element that is powered by the internal combustion engine so that an additional load is placed on the internal combustion engine in response to the determination by the control system.
22. The motor vehicle of claim 21, comprising the electrical load element is in the form of a catalytic converter heater.
23. The motor vehicle of claim 21, wherein the operating phase of the internal combustion engine is a start up phase.
24. The motor vehicle of claim 21, wherein:
- the motor vehicle is a hybrid vehicle that also includes at least one electric drive motor; and
- the operating phase of the internal combustion engine is one of a start up phase and an electrical drive phase.
25. A method of controlling an engine system having an internal combustion engine and a catalytic converter, the method comprising:
- determining that the catalytic converter is not within a predetermined operating range of temperature;
- based on said determining, activating a heater of the catalytic converter so that an additional load is placed on the internal combustion engine;
- drawing power away from the internal combustion engine to provide power to the activated heater while maintaining an engine speed of the internal combustion engine; and
- heating the catalytic converter with heat provided from both the heater and the internal combustion engine at least while the additional load is placed on the internal combustion engine.
Type: Application
Filed: Mar 24, 2009
Publication Date: Sep 30, 2010
Applicant: DENSO Corporation (Kariya-city)
Inventor: Peter Granqvist (Goteborg)
Application Number: 12/382,800
International Classification: F01N 9/00 (20060101); F01N 3/10 (20060101);