Patent Application
20170234208
The present disclosure relates to charge air coolers in the intake system of an internal combustion engine.
It is known to use charge air coolers (CACs) to cool down intake air that has been heated by a pressure charger, such as a turbocharger or supercharger. The power that can be developed by the engine is related to the amount of air that can be inducted into the cylinder. The colder the air, the denser the air, and consequently a greater amount of fuel can be burned in the cylinder thereby generating greater power. Additionally, having cooler air helps to resist engine knock or auto-ignition in a spark-ignition engine. Also, the lower the in-cylinder temperature due to the air being cooler, the less NOx that is formed during the combustion event.
In one prior art system, a CAC 16 is placed in a plenum of an intake manifold 10. Manifold 10 has an upper shell 12 and a lower shell 14 which forms a plenum 18 that houses CAC 16. Manifold 10 has a plurality of runners, a lower part 20 and an upper part 22 that are formed when upper shell 12 and lower shell 14 are affixed via friction welding or any other suitable process. A gasket 24 is provided between CAC 16 and upper and lower shells 12 and 14 to prevent intake air from shortcircuiting CAC 16. One shortcoming of such a configuration is that the coolant in the CAC proximate some cylinders is cooler than that in other cylinders leading to cylinder-to-cylinder variability in temperature. Also, because the intake manifold is heated by being under the hood of the vehicle, the air that is cooled in the plenum heats up during transit through the runners.
The inventor of the present disclosure has recognized that the effectiveness of the charge air cooler (CAC) is increased the closer that the CAC is located to the combustion chamber of the engine. An intake manifold that moves the CAC closer to the combustion chamber of an engine is disclosed. The manifold has an entrance, a plurality of intake runners, a plenum fluidly coupled to the intake runners, and a charger air cooler disposed in each of the intake runners.
The charge air coolers are placed in a downstream end of the intake runners.
Each charge air cooler has a plurality of heat exchange tubes located within the intake runners for conducting a cooling fluid therethrough.
The heat exchange tubes are coupled on an upstream end to a cooling fluid supply header and the heat exchange tubes are coupled on a downstream end to a cooling fluid return header.
A supply orifice and a return orifice are defined through the walls of each of the intake runners. The supply orifices allow a supply of cooling fluid to enter the charge air cooler and the return orifices allow a return of cooling fluid to leave the charge air cooler.
The charge air coolers are placed in an upstream end of the intake runners. In some embodiments, the charge air coolers are inserted in the intake runners prior to assembling the intake manifold.
The coolant is one of: water, a water and ethylene glycol mixture, and air.
The intake runners have a greater cross-sectional area along the length of the runners where the charge air coolers are inserted than along the length of the runners without a charge air cooler installed therein.
The charge air coolers are tube heat exchangers. Tubes of the tube heat exchangers obstruct a portion of the cross section of the runners. To overcome a drop in cross sectional area, a cross-sectional area of the runners is enlarged where the charge air coolers are provided.
Also disclosed is a method to assemble an intake manifold, including: fabricating a first portion of an intake manifold, fabricating a second portion of the intake manifold wherein the second portion includes a plurality of intake runners, inserting a charge air cooler into each of the intake runners, and affixing the first and second portions of the intake manifold.
In some embodiments, the charge air coolers are placed in an upstream end of the intake runners. Alternatively, they are place in a downstream end or along the length of the intake runners.
The method may further include coupling a coolant supply tube to an upstream end of each of the charge air coolers and coupling a coolant return tube to a downstream end of each of the charge air coolers.
The coolant supply tubes are coupled on an upstream end to a coolant supply header and the coolant return tubes are coupled on a downstream end to a coolant return header.
Also disclosed is, an intake manifold for an internal combustion engine having a first intake manifold section having an entrance and a plenum, a second intake manifold section having a plurality of runners adapted to couple to intake ports of the engine, a charge air cooler disposed in each of the runners, and a coolant supply and a coolant return coupled to each of the charge air coolers.
The manifold may further include a coolant supply header coupled to each of the coolant supplies and a coolant return header coupled to each of the coolant returns.
In some embodiments, the runners are of a greater cross-section along the length of the runners in which the charge air coolers are disposed compared to the runners without the charge air coolers.
The charge air coolers are heat exchangers that have a plurality of tubes disposed therein with intake air passing across outside surfaces of the tubes and coolant flowing through the tubes. The coolant is a water-based coolant in some embodiments and air in others.
By providing coolant to each CAC that is nearly the same temperature, the temperature of the air provided to each of the cylinders is nearly same, which presents an advantage of the prior art solution of having a single CAC. Furthermore, the air provided to the cylinders is cooler than it would otherwise be when the CAC is in the plenum. That is particularly the case for the CAC at the downstream end of the intake runner.
As those of ordinary skill in the art will understand, various features of the embodiments illustrated and described with reference to any one of the Figures may be combined with features illustrated in one or more other Figures to produce alternative embodiments that are not explicitly illustrated or described. The combinations of features illustrated provide representative embodiments for typical applications. However, various combinations and modifications of the features consistent with the teachings of the present disclosure may be desired for particular applications or implementations. Those of ordinary skill in the art may recognize similar applications or implementations whether or not explicitly described or illustrated.
In
In
An alternative configuration is shown in
The CAC presents some obstruction to the flow. Thus, in some embodiments, the cross-sectional area of the runner may be increased so that the cross-sectional area available for air flow is not significantly impaired. A small portion of a runner 120 houses a CAC in a section 122 as shown in
In
The CACs shown in
The fluid pumped through the CAC can be a liquid, such as engine coolant, or a gas, such as ambient air. An appropriate pump for the state of the fluid is provided. In some embodiments, the cooling system for the CAC is not solely for that purpose, but may be coupled with another cooling system on a vehicle, such as the engine cooling system. The engine coolant to the CAC could be cooled by the engine's radiator or have a separate radiator for the CAC that bring the temperature of the coolant to a lower temperature than might be used for cooling the engine.
While the best mode has been described in detail with respect to particular embodiments, those familiar with the art will recognize various alternative designs and embodiments within the scope of the following claims. While various embodiments may have been described as providing advantages or being preferred over other embodiments with respect to one or more desired characteristics, as one skilled in the art is aware, one or more characteristics may be compromised to achieve desired system attributes, which depend on the specific application and implementation. These attributes include, but are not limited to: cost, strength, durability, life cycle cost, marketability, appearance, packaging, size, serviceability, weight, manufacturability, ease of assembly, etc. The embodiments described herein that are characterized as less desirable than other embodiments or prior art implementations with respect to one or more characteristics are not outside the scope of the disclosure and may be desirable for particular applications.
