None.
1. Field of the Invention
This disclosure relates to an air inlet system for furnishing charge air, including recirculated exhaust gas, to the cylinders of a reciprocating internal combustion engine.
2. Related Art
Diesel engines, while offering excellent fuel economy, must be controlled ever more stringently in terms of exhaust emissions, particularly oxides of nitrogen (NOx) and particulate matter. In an effort to control NOx without causing an undue loss in fuel economy, engine designers have relied upon increasingly higher amounts of exhaust gas recirculation (EGR). More specifically, EGR rates of approximately 30% at peak power conditions and 60% at low speed and load are on the horizon. Unfortunately, it is difficult to furnish very high amounts of EGR to an engine's cylinders in a uniform manner. That is, without providing too much EGR to one cylinder while too little to others. Maldistribution of EGR causes an engine to run rough and with unacceptable emissions. Furthermore, this can lead to undesirable temperature nonuniformities in various engine components. Although an extremely lengthy intake tract may be used to provide adequate mixing of EGR with the other components of charge air, a long intake tract may not be package feasible, particularly in vehicular applications.
It would be desirable to provide an inlet system for an internal combustion engine, such as a diesel engine, having the capability of fully mixing large amounts of EGR in a charge air stream so as to prepare a uniform mixture for induction into the engine's power cylinders. It would further be desirable to minimize the package volume required for an engine's air induction system.
According to an aspect of the present invention, an air supply system for a reciprocating internal combustion engine includes an air inlet connected to a mixing volute. The mixing volute is configured to impart swirl in a first direction to air passing from the air inlet and through the mixing volute. An EGR injector introduces exhaust gas into air passing through the mixing volute. The EGR injector is configured to impart swirl in a second direction to EGR gases passing through the injector and into charge air flowing through the mixing volute, so that the EGR gases and air will become mixed while traveling through the mixing volute. An intake system conducts mixed air and EGR gases from the mixing volute to one or more power cylinders of the engine.
According to another aspect of the present invention, the EGR injector is located at an axial centerline line of the volute, with the EGR injector including an exhaust gas passage and a flow director, positioned at the discharge end of the exhaust gas passage, and causing EGR gases to be discharged with a swirling motion. The EGR injector causes the swirling motion of the exhaust gases to have a direction of rotation which is opposite the direction or rotation imparted by the mixing volute to charge air flowing through the mixing volute. In this manner, excellent mixing of the air and exhaust gases is achieved.
According to another aspect of the present invention, the mixing volute and EGR injector are located within a common housing containing a charge air compressor inlet duct. In an embodiment, the compressor inlet duct is bifurcated.
It is an advantage of an air supply system according to the present invention that the system is particularly useful for use with V-block engines having relatively shorter induction air flow paths than those typically associated with in-line engines.
It is an advantage of an air induction system according to the present invention that EGR will be introduced not only into the core portion of the air flowing into the engine, but also into the boundary or more remote portions of the flow so as to promote an even distribution of EGR to the engine's cylinders.
It is another advantage of a system according to the present invention that pressure drop on both the EGR and charge air sides of the inducted gases will be minimized.
It is yet another advantage of a system according to the present invention that an engine equipped with this system may be optimized for minimum exhaust emissions because of the more finely regulated and even distribution of EGR to the engine's various cylinders.
It is yet another advantage of the present invention that, as a result of more even EGR flow to each cylinder, the cylinders will develop nearly identical peak pressures, permitting the engine to be calibrated at peak power to take maximum advantage of each cylinder instead of being restricted because of maldistribution of the cylinder pressures.
It is yet another advantage of a system according to the present invention that fuel economy will be improved because of the absence of a need to retard injection timing with a diesel engine to achieve mandated NOx levels.
It is yet another advantage of a system according to the present invention that the noise, vibration, and harshness (NVH) of an engine will be improved with the present system because even distribution of EGR will prevent discordant sounding combustion.
It is yet another advantage of a system according to the present invention that the package volume of an air induction system having turbocharging and intercooling, particularly in the context of a V-block engine, may be reduced.
Other advantages, as well as features of the present invention, will become apparent to the reader of this specification.
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Details of combination turbocharger compressor inlet and EGR mixer 10 are shown in
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According to another aspect of the present invention, a method for supplying charge air to an internal combustion engine includes drawing charge air into a turbocharger compressor, followed by reducing the temperature of compressed air flowing from the compressor by passing the compressed air through an intercooler. The charge air is passed from the intercooler through an EGR mixer, wherein the charge air is caused to swirl in a first direction of rotation through a mixing volute located within the EGR mixer. Exhaust gases are introduced into the EGR mixer. The exhaust gases are introduced into the EGR mixer so as to swirl through the mixing volute in a second direction of rotation, whereby the charge air and the exhaust gases will become mixed. Then the mixed charge air, containing exhaust gas, is introduced to the engine. Optionally, the method further includes passing charge air to the turbocharger compressor through an inlet duct contained within a housing containing the mixing volute.
The foregoing invention has been described in accordance with the relevant legal standards, thus the description is exemplary rather than limiting in nature. Variations and modifications to the disclosed embodiment may become apparent to those skilled in the art and fall within the scope of the invention. Accordingly the scope of legal protection afforded this invention can only be determined by studying the following claims.