AFTERTREATMENT SYSTEM FOR MOTOR VEHICLE
An aftertreatment system for an internal combustion engine includes a diesel cold start catalyst member, a lean NOx trap (LNT) member arranged directly adjacent to and downstream of the diesel cold start catalyst, and a selective catalyst reduction (SCR) member arranged downstream of the LNT. The diesel cold start catalyst is operable to reduce NOx emissions at operating temperatures below 200° C. and the LNT and SCR system are operable to reduce NOx emissions at operating temperatures above 200° C.
The subject disclosure relates to the art of aftertreatment systems and, more particularly, to an aftertreatment system for a motor vehicle.
Internal combustions engines, when operated, often produce undesirable gases such as CO, CO2, NOx, and the like. Many countries have introduced regulations limiting emissions from internal combustion engines. Various aftertreatment systems have been introduced to reduce emissions. In many instances, existing aftertreatment systems operate during normal operating conditions. During normal operating conditions, exhaust components have been heated to operating temperatures which may be in excess of about 175° C.
New emissions regulations are being implemented to address emissions that may occur below normal operating temperatures. Current aftertreatment systems may employ an electric heater positioned to heat an aftertreatment catalyst to further reduce emissions during, for example, cold starts. Electric heaters add additional components that necessitate periodic maintenance and increase an overall complexity of aftertreatment devices. Further, electric heaters require a warm up period during such time as emissions may occur at levels that do not meet current and pending regulations. Accordingly, it is desirable to provide an aftertreatment system that operates during cold starts to reduce emissions of an internal combustion engine operating below normal operating temperatures.
SUMMARYIn one exemplary embodiment, an aftertreatment system for an internal combustion engine includes a diesel cold start catalyst member, a lean NOx trap (LNT) member arranged directly adjacent to and downstream of the diesel cold start catalyst, and a selective catalyst reduction (SCR) member arranged downstream of the LNT. The diesel cold start catalyst is operable to reduce NOx emissions at operating temperatures below 200° C. and the LNT and SCR system are operable to reduce NOx emissions at operating temperatures above 200° C.
In addition to one or more of the features described above or below, or as an alternative, further embodiments could include a diesel exhaust fluid (DEF) injection system operable to introduce a diesel exhaust fluid into exhaust gases produced by the internal combustion engine.
In addition to one or more of the features described above or below, or as an alternative, further embodiments could include wherein the DEF injection system is arranged downstream of the LNT and upstream of the SCR.
In addition to one or more of the features described above or below, or as an alternative, further embodiments could include a transfer tube fluidically connecting the diesel cold start catalyst and LNT with the SCR.
In addition to one or more of the features described above or below, or as an alternative, further embodiments could include wherein the DEF injection system is fluidically connected to the transfer tube.
In addition to one or more of the features described above or below, or as an alternative, further embodiments could include wherein the DEF injection system comprises a urea injector.
In addition to one or more of the features described above or below, or as an alternative, further embodiments could include at least one of an O2/NOx sensor and an exhaust gas temperature (EGT) sensor arranged upstream of the diesel cold start catalyst, and at least one of an O2/NOx sensor and an EGT sensor arranged downstream of the LNT.
In addition to one or more of the features described above or below, or as an alternative, further embodiments could include a first differential pressure sensor (DPS) arranged upstream of the SCR and a second DPS arranged downstream of the SCR.
In addition to one or more of the features described above or below, or as an alternative, further embodiments could include wherein the diesel cold start catalyst and LNT are arranged in a common housing.
In addition to one or more of the features described above or below, or as an alternative, further embodiments could include a rear oxidation catalyst (ROC) arranged downstream of the SCR.
In accordance with another aspect of an exemplary embodiment, a motor vehicle includes an internal combustion engine including an exhaust system, and an aftertreatment system fluidically connected to the exhaust system. The aftertreatment system includes a diesel cold start catalyst (diesel cold start catalyst) member, a lean NOx trap (LNT) member arranged directly adjacent to and downstream of the diesel cold start catalyst, and a selective catalyst reduction (SCR) member arranged downstream of the LNT. The diesel cold start catalyst is operable to reduce NOx emissions at operating temperatures below 200° C. and the LNT and SCR system are operable to reduce NOx emissions at operating temperatures above 200° C.
In addition to one or more of the features described above or below, or as an alternative, further embodiments could include a diesel exhaust fluid (DEF) injection system operable to introduce a diesel exhaust fluid into exhaust gases produced by the internal combustion engine.
In addition to one or more of the features described above or below, or as an alternative, further embodiments could include wherein the DEF injection system is arranged downstream of the LNT and upstream of the SCR.
In addition to one or more of the features described above or below, or as an alternative, further embodiments could include a transfer tube fluidically connecting the diesel cold start catalyst and LNT with the SCR.
In addition to one or more of the features described above or below, or as an alternative, further embodiments could include wherein the DEF injection system is fluidically connected to the transfer tube.
In addition to one or more of the features described above or below, or as an alternative, further embodiments could include wherein the DEF injection system comprises a urea injector.
In addition to one or more of the features described above or below, or as an alternative, further embodiments could include a diesel exhaust fluid (DEF) injection system arranged downstream of the LNT.
In addition to one or more of the features described above or below, or as an alternative, further embodiments could include at least one of an O2/NOx sensor and an exhaust gas temperature (EGT) sensor arranged upstream of the diesel cold start catalyst, and at least one of an O2/NOx sensor and an EGT sensor arranged downstream of the LNT.
In addition to one or more of the features described above or below, or as an alternative, further embodiments could include a first differential pressure sensor (DPS) arranged upstream of the SCR and a second DPS arranged downstream of the SCR.
In addition to one or more of the features described above or below, or as an alternative, further embodiments could include wherein the diesel cold start catalyst and LNT are arranged in a common housing.
The above features and advantages, and other features and advantages of the disclosure are readily apparent from the following detailed description when taken in connection with the accompanying drawings.
Other features, advantages and details appear, by way of example only, in the following detailed description, the detailed description referring to the drawings in which:
The following description is merely exemplary in nature and is not intended to limit the present disclosure, its application or uses. It should be understood that throughout the drawings, corresponding reference numerals indicate like or corresponding parts and features.
A motor vehicle, in accordance with an aspect of an exemplary embodiment, is indicated generally at 10 in
In accordance with an aspect of an exemplary embodiment illustrated in
In accordance with an aspect of an exemplary embodiment, aftertreatment system 34 includes a diesel cold start catalyst member 60 and a lean NOx trap (LNT) member 64 arranged in a common housing 66. While arranged in a common housing, it is to be understood that diesel cold start catalyst member 60 and LNT member 64 may exist in the common housing as separate components or bricks. Further, it is to be understood that diesel cold start catalyst member 60 and LNT member 64 may each include a unique substrate with specific zone-coating that provides a separation between bricks. LNT member 64 is arranged downstream of diesel cold start catalyst member 60 as will become evident herein. Exhaust gases enter into, and raise an internal temperature of, LNT member 64 after being processed by diesel cold start catalyst member 60. Common housing 66 includes an inlet 69 fluidically connected to turbine outlet 50 and an outlet 71 that is fluidically connected to a transfer tube 74. Diesel cold start catalyst member 60 operates to reduce NOx emissions in exhaust gases that are at temperatures below about 200° C. and LNT member 64 operates to reduce NOx emissions that may be present in exhaust gases that are at a temperature in excess of about 200° C. In this manner, diesel cold start catalyst member 60 and LNT member 64 operate in tandem to reduce NOx emissions that may be present in exhaust gases from initial start up to normal operating conditions.
More specifically, at initial startup, the temperature of exhaust gases passing from internal combustion engine system 24 is typically below 200° C. Diesel cold start catalyst member 60 may include a catalyst and/or zeolite trap (not separately labeled) configured to reduce NOx emissions in exhaust gases at start up temperature. Exhaust gas temperatures starts to climb with continued operation of internal combustion engine system 24 and LNT member 64 is heated. As exhaust gas temperatures approach operating temperatures of about 200° C. or higher, diesel cold start catalyst member 60 begins to lose NOx emission reduction efficacy. However, LNT member 64, being heated by the exhaust gases passing from diesel cold start catalyst member 60, has reached an effective operating temperature. As such, as the efficacy of diesel cold start catalyst member 60 drops, LNT member 64 takes over to continue to reduce NOx emissions.
In further accordance with an exemplary aspect, a transfer tube 74 includes an inlet portion 77 fluidically connected to outlet 71 and an outlet portion 79 fluidically connected to a selective catalyst reduction (SCR) system 84. SCR system 84 may also take the form of an SCRF system which includes a diesel particulate filter system. SCR system 84 processes the exhaust gases passing from LNT member 64 to further reduce emissions. SCR system 84 includes an inlet section 86 fluidically connected to outlet portion 79 of transfer tube 74 and an outlet section 88 that may be connected to a rear oxidation catalyst (ROC) 91 through an exhaust conduit 94. ROC 91 is fluidically connected to exhaust outlet pipe 36 and operates to oxidize gases such as CO, HC, and NH3 that may pass from SCR system 84.
In still further accordance with an aspect of an exemplary embodiment, a diesel exhaust fluid (DEF) injection system 114 may be arranged downstream of LNT member 64 and upstream of SCR system 84. DEF injection system 114 may be selectively controlled to introduce an amount of diesel exhaust fluid into the exhaust gases passing through, for example, transfer tube 74. In accordance with an aspect of an exemplary embodiment, DEF injection system 114 includes a urea injector. It is to be understood that DEF injection system 114 may be configured to introduce a wide range of diesel exhaust fluids into the exhaust gases passing into transfer tube 74. The introduction of diesel exhaust fluid may be controlled based on inputs from various sensors associated with aftertreatment system 34 to still further reduce emissions, particularly NOx.
In still further accordance with an exemplary aspect, aftertreatment system 34 may include a first O2/NOx sensor 124 arranged in inlet 69 of common housing 66 and a second O2/NOx sensor 125 arranged at outlet 71 of common housing 66. Additionally, a first exhaust gas temperature (EGT) sensor 130 is arranged in inlet 69 and a second EGT sensor 131 is arranged at outlet 71. Also, a first differential pressure sensor (DPS) 134 is arranged at inlet section 86 of SCR system 84 and a second DPS 135 is arranged at outlet section 88 of SCR system 84. Each of the above sensors may be connected to a controller (not shown) which may be employed to control aspects of turbocharger 40, such as waste gate position, DEF injection system 114 and the like.
It is to be understood that exemplary embodiments describe a system for reducing NOx emissions produced by an internal combustion engine during both a cold start period and normal operating conditions. The diesel cold start catalyst (diesel cold start catalyst) member of the present invention is positioned so as to both process exhaust gases during a cold start or gases at temperatures below about 200° C. as well as provide a pre-heat function for a lean NOx trap positioned downstream. In this manner, the exemplary embodiment eliminates the need for electric pre-heaters that must be operated to pre-heat the LNT member. Further, the particular arrangement of components provides a broader range of emission reduction that spans cold start, e.g., below about 200° C., and normal operation, e.g., exhaust temperatures above about 200° C., in order to meet new emission regulations.
The term “about” is intended to include the degree of error associated with measurement of the particular quantity based upon the equipment available at the time of filing the application. For example, “about” can include a range of +8% or 5%, or 2% of a given value. Further, the term “about” should be understood to represent a general indication of temperature values as particular temperature values may be dependent upon various system constraints, materials employed and the like.
While the above disclosure has been described with reference to exemplary embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from its scope. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the disclosure without departing from the essential scope thereof. Therefore, it is intended that the invention not be limited to the particular embodiments disclosed, but will include all embodiments falling within the scope of the application.
Claims
1. An aftertreatment system for an internal combustion engine comprising:
- a diesel cold start catalyst member;
- a lean NOx trap (LNT) member arranged directly adjacent to and downstream of the diesel cold start catalyst; and
- a selective catalyst reduction (SCR) member arranged downstream of the LNT, wherein the diesel cold start catalyst is operable to reduce NOx emissions at operating temperatures below 200° C. and the LNT and SCR system are operable to reduce NOx emissions at operating temperatures above 200° C.
2. The aftertreatment system according to claim 1, further comprising: a diesel exhaust fluid (DEF) injection system operable to introduce a diesel exhaust fluid into exhaust gases produced by the internal combustion engine.
3. The aftertreatment system according to claim 2, wherein the DEF injection system is arranged downstream of the LNT and upstream of the SCR.
4. The aftertreatment system according to claim 2, further comprising: a transfer tube fluidically connecting the diesel cold start catalyst and LNT with the SCR.
5. The aftertreatment system according to claim 3, wherein the DEF injection system is fluidically connected to the transfer tube.
6. The aftertreatment system according to claim 2, wherein the DEF injection system comprises a urea injector.
7. The aftertreatment system according to claim 1, further comprising: at least one of an O2/NOx sensor and an exhaust gas temperature (EGT) sensor arranged upstream of the diesel cold start catalyst, and at least one of an O2/NOx sensor and an EGT sensor arranged downstream of the LNT.
8. The aftertreatment system according to claim 1, further comprising: a first differential pressure sensor (DPS) arranged upstream of the SCR and a second DPS arranged downstream of the SCR.
9. The aftertreatment system according to claim 1, wherein the diesel cold start catalyst and LNT are arranged in a common housing.
10. The after treatment system according to claim 1, further comprising: a rear oxidation catalyst (ROC) arranged downstream of the SCR.
11. A motor vehicle comprising:
- an internal combustion engine including an exhaust system; and
- an aftertreatment system fluidically connected to the exhaust system, the aftertreatment system comprising:
- a diesel cold start catalyst member;
- a lean NOx trap (LNT) member arranged directly adjacent to and downstream of the diesel cold start catalyst; and
- a selective catalyst reduction (SCR) member arranged downstream of the LNT, wherein the diesel cold start catalyst is operable to reduce NOx emissions at operating temperatures below 200° C. and the LNT and SCR system are operable to reduce NOx emissions at operating temperatures above 200° C.
12. The motor vehicle according to claim 11, further comprising: a diesel exhaust fluid (DEF) injection system operable to introduce a diesel exhaust fluid into exhaust gases produced by the internal combustion engine.
13. The motor vehicle according to claim 12, wherein the DEF injection system is arranged downstream of the LNT and upstream of the SCR.
14. The motor vehicle according to claim 12, further comprising: a transfer tube fluidically connecting the diesel cold start catalyst and LNT with the SCR.
15. The motor vehicle according to claim 14, wherein the DEF injection system is fluidically connected to the transfer tube.
16. The motor vehicle according to claim 10, wherein the DEF injection system comprises a urea injector.
17. The motor vehicle according to claim 10, further comprising: a diesel exhaust fluid (DEF) injection system arranged downstream of the LNT.
18. The motor vehicle according to claim 10, further comprising: at least one of an O2/NOx sensor and an exhaust gas temperature (EGT) sensor arranged upstream of the diesel cold start catalyst, and at least one of an O2/NOx sensor and an EGT sensor arranged downstream of the LNT.
19. The motor vehicle according to claim 10, further comprising: a first differential pressure sensor (DPS) arranged upstream of the SCR and a second DPS arranged downstream of the SCR.
20. The motor vehicle according to claim 10, wherein the diesel cold start catalyst and LNT are arranged in a common housing.
Type: Application
Filed: Mar 23, 2017
Publication Date: Sep 27, 2018
Inventors: Andrea De Filippo (Turin), Andrea Pannuzzo (Turin), Wei Li (Troy, MI)
Application Number: 15/467,440
