This disclosure relates generally to an exhaust gas aftertreatment component in a multiple path configuration.
An exhaust system conducts hot exhaust gases generated by an engine through various exhaust components to reduce emissions and control noise. In one traditional configuration, the exhaust system includes an injection system that injects a NOx reduction fluid such as urea, NH3 carbonate, or any reduction gas or liquid that is a solution of urea and water for example, upstream of a selective catalytic reduction (SCR) catalyst. The injection system includes a doser or injector that sprays the injected fluid into the exhaust stream. The spray is typically concentrated in one area and then spreads out to mix with the exhaust gases. The urea from the injected fluid should be transformed as much as possible into ammonia (NH3) before reaching the SCR catalyst. Low temperature conditions and certain packaging configurations can make this transformation more difficult.
An exhaust system according to an exemplary aspect of the present disclosure includes, among other things, a first aftertreatment substrate configured to receive exhaust gases from an engine and a second aftertreatment substrate downstream of the first aftertreatment substrate, wherein the first aftertreatment substrate is smaller than the second aftertreatment substrate. A multi-way valve configured to direct exhaust gas through the first aftertreatment substrate prior to entering the second aftertreatment substrate when an exhaust gas temperature is below a first predetermined temperature, and is configured to allow exhaust gas to bypass the first aftertreatment substrate and enter the second aftertreatment substrate when the exhaust gas temperature is above a second predetermined temperature, and is configured to allow exhaust gas to be directed through both the first and second aftertreatment substrates when between the first and second predetermined temperatures.
In a further non-limiting embodiment of the foregoing system, the first aftertreatment substrate and the second aftertreatment substrate comprise SCR substrates.
In a further non-limiting embodiment of any of the foregoing systems, a DOC or DOC/DPF and a mixer are upstream of the second aftertreatment substrate and downstream of the first aftertreatment substrate.
In a further non-limiting embodiment of any of the foregoing systems, an injection system has at least a first doser configured to inject a reducing agent into the mixer and a second doser configured to inject the reducing agent upstream of the first aftertreatment substrate.
In a further non-limiting embodiment of any of the foregoing systems, the first aftertreatment substrate is positioned immediately downstream of a turbocharger, and the system includes a housing that surrounds the second aftertreatment substrate, a first pipe having a first pipe end in fluid communication with a turbocharger outlet pipe and a second pipe end in fluid communication with an inlet to the housing, and a second pipe having a first pipe end in fluid communication with the turbocharger outlet pipe and a second pipe end in fluid communication with the inlet to the housing, and wherein the multi-way valve is positioned within one of the first pipe and the second pipe.
In a further non-limiting embodiment of any of the foregoing systems, the multi-way valve is positioned within the first pipe and the first aftertreatment substrate is positioned within the second pipe to provide a parallel configuration.
In a further non-limiting embodiment of any of the foregoing systems, the multi-way valve is positioned within the first pipe and the first aftertreatment substrate is positioned within the first pipe downstream of the multi-way valve, and wherein when the multi-way valve is in a closed position exhaust gas bypasses the first aftertreatment substrate and flows through the second pipe to the inlet to the housing.
In a further non-limiting embodiment of any of the foregoing systems, the multi-way valve is positioned within the first pipe and the first aftertreatment substrate is positioned within the second pipe, and wherein when the multi-way valve is in a closed position exhaust gas flows through the second pipe into the first aftertreatment substrate.
In a further non-limiting embodiment of any of the foregoing systems, the first aftertreatment substrate is positioned immediately downstream of a turbocharger, and the system includes a housing that surrounds the second aftertreatment substrate, a first plenum that fluidly connects an outlet from the first aftertreatment substrate to the inlet to the housing, a second plenum in fluid communication with a turbocharger outlet pipe, wherein the first aftertreatment substrate is positioned between the first and second plenums, and a pipe portion connecting the second plenum to the first plenum and extending parallel to the first aftertreatment substrate, and wherein the multi-way valve is located within the pipe portion.
An exhaust system, according to yet another exemplary aspect of the present disclosure includes, among other things, a first aftertreatment component including at least one first aftertreatment substrate configured to receive exhaust gases from an engine and a second aftertreatment component downstream of the first aftertreatment component. A first housing surrounds at least one upstream substrate, a second housing surrounds at least one second aftertreatment substrate, and a mixer has a mixer housing with an upstream end connected to the first housing and a downstream end connected to the second housing. The first aftertreatment substrate is smaller than the second aftertreatment substrate. A multi-way valve configured to direct exhaust gas through the first aftertreatment substrate prior to entering the second aftertreatment substrate when an exhaust gas temperature is below a first predetermined temperature, and is configured to allow exhaust gas to bypass the first aftertreatment substrate and enter the second aftertreatment substrate when the exhaust gas temperature is above a second predetermined temperature, and is configured to allow exhaust gas to be directed through both the first and second aftertreatment substrates when between the first and second predetermined temperatures.
In a further non-limiting embodiment of any of the foregoing systems, the at least one first aftertreatment substrate and the at least one second aftertreatment substrate comprise SCR substrates, and wherein the upstream substrate comprises a DOC or DOC/DPF, and the system includes an injection system with at least a first doser configured to inject a reducing agent into the mixer and a second doser configured to inject the reducing agent upstream of the first aftertreatment substrate, and wherein where the multi-way valve and the first and second dosers are controlled by at least one electronic control unit.
The embodiments, examples and alternatives of the preceding paragraphs, the claims, or the following description and drawings, including any of their various aspects or respective individual features, may be taken independently or in any combination. Features described in connection with one embodiment are applicable to all embodiments, unless such features are incompatible.
The various features and advantages of the disclosed examples will become apparent to those skilled in the art from the detailed description. The figures that accompany the detailed description can be briefly described as follows:
This disclosure details an exemplary exhaust system with a light off aftertreatment component having a bypass configuration.
As shown in
Upstream of the in-line exhaust aftertreatment assembly 20 is a bypass arrangement 40 that includes an additional aftertreatment exhaust component. In one example, the bypass arrangement 40 includes an aftertreatment substrate 42 and a valve 44. The bypass arrangement 40 is configured to provide ultra low NOx emission and facilitate the reduction of cold start emissions. The bypass arrangement 40 can comprise various configurations, examples of which are shown in
Exhaust gas exits the bypass arrangement 40 and enters the first exhaust component 22 of the in-line exhaust aftertreatment assembly 20. In one example, the first aftertreatment substrate 24 of the first exhaust component 22 comprises a diesel oxidation catalyst (DOC) or a DOC combined with a diesel particulate filter (DPF). Exhaust gas exits the first exhaust component 22 and enters the mixer 26, which is used to direct a mixture of a reducing agent and engine exhaust gases into the second aftertreatment substrate 30 of the second exhaust component 28. The second aftertreatment substrate 30 comprises at least one catalytic reduction (SCR) substrate 24, for example. Downstream of the second aftertreatment substrate 30 there may be various additional downstream exhaust components 46, which can include pipes, mufflers, resonators, etc. The downstream exhaust components 46 direct the exhaust gases to an outlet to atmosphere via a tailpipe 48. The components can be mounted in various different configurations and combinations dependent upon the type of application and available packaging space.
An injection system 50 includes an injector or doser 52 that delivers a reducing agent, e.g., a NOx reduction fluid such as urea, NH3 carbonate, or any reduction gas or liquid that is a solution of urea and water, into an internal cavity 54 of the mixer 26 and upstream of the second aftertreatment substrate 30. The operation of the doser 52 is known, and any type of injector or doser can be used. The mixer 26 mixes engine exhaust gases with the injected reducing agent. In one example, the doser 52 is mounted to an outer peripheral surface of an outer housing 56 of the mixer 26 at a doser mount interface 58 as shown in
In one example, the bypass arrangement 40 includes a second injector or doser 64 as shown in
The controller 62 can include a processor, memory, and one or more input and/or output interfaces that are communicatively coupled via a local interface including one or more buses and/or other wired or wireless connections, for example. The controller 62 operates as known and may be a hardware device for executing software and can comprise a processor, a central processing unit (CPU), or generally any device for executing software instructions. The controller 62 can be a main vehicle controller or a dedicated controller for the exhaust system. One or more vehicle sensors 38 provide vehicle data to the controller 62. In one example, the sensors 38 include a temperature sensor to sense a temperature of the ambient environment.
The bypass arrangement 40 provides for the upstream aftertreatment substrate, e.g. the upstream SCR, to be smaller in size than the downstream aftertreatment substrate 30, e.g. the downstream SCR. The multi-way valve 44 is configured to direct exhaust gas through the upstream SCR prior to entering the downstream SCR when an exhaust gas temperature is, for example, below a predetermined temperature, and is configured to allow exhaust gas to bypass the upstream SCR and enter the downstream SCR when the exhaust gas temperature is above the predetermined temperature. This allows for a smaller diameter (smaller size) light off SCR to be brought closer the engine heat source to reduce thermal inertial and enable earlier light off. The smaller size SCR provides for a faster light off during a cold start condition, but is flow restrictive at higher exhaust gas flow rates when the system is at a desired operating temperature and the light off SCR is no longer needed. This enables a close-coupled aftertreatment and conventional aftertreatment system to work independently throughout the full operating range of the engine 12 without back pressure penalty. Additionally or alternatively, there may be a second predetermined temperature. In such a case, a multi-way valve may be configured to direct exhaust gas through the first aftertreatment substrate prior to entering the second aftertreatment substrate when an exhaust gas temperature is below a first predetermined temperature, and is configured to allow exhaust gas to bypass the first aftertreatment substrate and enter the second aftertreatment substrate when the exhaust gas temperature is above a second predetermined temperature, and is configured to allow exhaust gas to be directed through both the first and second aftertreatment substrates when between the first and second predetermined temperatures.
Examples of the bypass arrangement 40 are shown in
In the example of
In one example, the first aftertreatment substrate 42 includes a center housing 96, an inlet cone 98 connected to an upstream end of the center housing 96, and an outlet cone 100 connected to the downstream end of the center housing 96. In one example, the inlet cone 98 includes the doser mount interface 66 that is configured to receive the doser 64.
In the example of
Although a specific component relationship is illustrated in the figures of this disclosure, the illustrations are not intended to limit this disclosure. In other words, the placement and orientation of the various components shown could vary within the scope of this disclosure. In addition, the various figures accompanying this disclosure are not necessarily to scale, and some features may be exaggerated or minimized to show certain details of a particular component.
The preceding description is exemplary rather than limiting in nature. Variations and modifications to the disclosed examples may become apparent to those skilled in the art that do not necessarily depart from the essence of this disclosure. Thus, the scope of legal protection given to this disclosure can only be determined by studying the following claims.