Patent Application
20170306901
Internal combustion engines often incorporate exhaust gas recirculation (EGR) systems to improve exhaust gas quality and fuel efficiency of the engine. In an internal combustion engine, where peak combustion temperature can exceed 2,500 degrees F. (1,372 degrees C.), nitrogen in the air reacts with oxygen to produce nitrous oxides (NOx). To reduce the level of NOx emissions, an EGR system routes a portion of the exhaust gas to a location upstream of the internal combustion engine where it is mixed with the fresh air supply and then recirculated to the internal combustion engine. The mixture of the exhaust gas with the fresh air supply dilutes the incoming fuel charge, thereby lowering flame temperatures. One location for mixing the exhaust gas with the fresh air supply may be at the intake manifold of the engine.
For internal combustion engines incorporating an EGR system, tubes through which the exhaust gas is routed to the intake manifold run external to the intake manifold, and therefore, more space is required in an engine compartment in which the internal combustion engine and intake manifold are housed. However, weight and space restraints are becoming more critical in vehicles as the designs are becoming more streamlined. One area in which a reduction in space is desired is the engine compartment.
Therefore, there exists a need for an intake manifold incorporating exhaust gas recirculation in a more compact manner to reduce the amount of space that the intake manifold may occupy, for example, within an engine compartment of a vehicle.
Exhaust gas recirculation (EGR) may be employed in conjunction with an intake manifold of an internal combustion engine to reduce NOx emissions. To conserve space, for example, within an engine compartment of a vehicle, the intake manifold may include an internal EGR tube. An exemplary intake manifold may include an upper manifold configured to receive fresh air, an EGR tube configured to introduce exhaust gas into the upper manifold to be mixed with the fresh air, and a lower manifold configured to distribute the mixture of the fresh air and the exhaust gas cylinders of the internal combustion engine. The upper manifold may include an upper shell and a lower shell that may cooperate to define at least one channel in which at least a portion of the EGR tube may be secured.
An exemplary process of manufacturing an intake manifold, such as the exemplary intake manifold described above, may include first forming a lower shell and an upper shell of an upper manifold of the intake manifold, where at least one of the lower shell and the upper shell define at least one channel. The process may then include forming an EGR tube having at least one portion that corresponds to the at least one channel. The process may then include inserting the at least one portion of the EGR tube into the at least one channel. The process may further include attaching the upper shell to the lower shell such that the EGR tube is secured therebetween.
Referring now to the figures,
The intake manifold 10 may also include an exhaust gas recirculation (EGR) tube 20 secured within the upper manifold 12, as described in more detail hereinafter. The EGR tube 20 generally may be configured to introduce exhaust gas from the internal combustion engine into the upper manifold 12 to be mixed with the fresh air. The resulting mixture may then be distributed to cylinders (not shown) of the internal combustion engine. The EGR tube 20 may be located near the air intake 22 such that the exhaust gas may be mixed with the fresh air as it enters the intake manifold 10 to increase the mixing before distribution to the engine cylinders. The lower manifold 14 may include an exhaust gas conduit 24 by which the exhaust gas may flow from the internal combustion engine to the EGR tube 20. The intake manifold 10 may further include a collar 26 connecting the EGR tube 20 and the exhaust gas conduit 24. The collar 26 may also serve as a seal preventing the exhaust gas from coming into contact with any portion of the upper manifold 12 without first being mixed with the fresh air.
Because the exhaust gas may be at very high temperatures (e.g., approximately 200 degrees C.), the EGR tube 20 may be made of a material to withstand such high temperatures. For example, the material may be configured to withstand continuous temperatures as high as 220 degrees C., and intermittent temperatures as high as 240 degrees C. Exemplary materials may include, but are not limited to, plastics, such as a polyamide resin. A plastic material may enable the EGR tube 20 to be lighter and manufactured at a lower cost than other materials, such as steel or metal. Further, the plastic withstands the heat from the exhaust gas, and therefore insulates the intake manifold 10 from the heat, as opposed to conducting the heat from the exhaust gas to the upper manifold 12. In contrast, the upper manifold 12 does not come into direct contact with the exhaust gas, only with combustible mixture at a lower temperature. Therefore, the material of the upper shell 16 and the lower shell 18 does not have to be able to withstand the same high temperatures as the material of the EGR tube 20. For example, the material may be plastic configured to withstand a maximum temperature of only 150 degrees C.
To distribute the mixture of fresh air and exhaust gas to the engine cylinders, the upper shell 16 and the lower shell 18 may define plenums 28a, 28b into which the fresh air may flow from the air intake 22 and the exhaust gas may flow from the EGR tube 20, as seen in
The upper shell 16 and the lower shell 18 may also define channels 30 each in fluid communication with at least one of the plenums 28a, 28b, and the lower manifold 14 may define a plurality of ports 32 each corresponding to one of the channels 30 and to one of the engine cylinders. In general, the number of channels 30 and ports 32 may correspond to the number of cylinders of the internal combustion engine. While the figures depict a total of six channels 30 and six ports 32 for a 6-cylinder engine, it should be appreciated that the intake manifold 10 may be configured for an internal combustion engine of any number of cylinders, including a 4-cylinder engine and an 8-cylinder engine. After the exhaust gas and the fresh air mix, the mixture may then flow through the plenums 28a, 28b to each of the channels 30 into the ports 32 to the engine cylinders.
As seen in
To secure the EGR tube 20 within the upper manifold 12, the lower shell 18 may define a first channel 40 in which the first portion 34 of the EGR tube 20 may be inserted, and the upper shell 16 and the lower shell 18 may cooperate to define a second channel 42 in which the second portion 36 of the EGR tube 20 may sit. The upper shell 16 may define an upper portion 44 of the channel 42 and the lower shell 18 may define a lower portion 46 of the second channel 42. The first channel 40 and the second channel 42 generally may have the same shape and configuration as the first portion 34 and the second portion 36, respectively. For example, where the second portion 36 of the EGR tube 20 is curved, the second channel 42 may similarly be curved with the same curvature radius. The cross-sectional areas of the first channel 40 and the second channel 42 may be slightly larger than the respective cross-sectional areas of the first portion 34 and the second portion 36 such that the first portion 34 and the second portion 36 may be easily installed during assembly of the upper manifold 12.
To further secure the EGR tube 20 within the upper manifold 12, the second portion 36 of the EGR tube 20 may include tabs 48 extending from the second portion 36, as seen in
The tabs 48 may fit within corresponding grooves 50 in ridges 52 of the lower shell 18. The tabs 48 may be joined together with the grooves 50 and/or the ridges 52 to permanently attach the EGR tube 20 to the lower shell 18. Any process may be used to join the tabs 48 to the grooves 50 and/or the ridges 52, including, but not limited to, welding, friction welding, soldering, or the like. Thus, the EGR tube 20 may be secured within the upper manifold 12 without the use of any external fasteners.
Referring now to
After block 104, process 100 may proceed to block 106 in which the EGR tube 20 may be formed. The EGR tube 20 may be formed by any process or combination of processes, including, but not limited to, molding and welding. For example, the EGR tube 20 may be formed by a one-step injection molding process. Alternatively, each of the portions 34 and 36 may be formed by a one-step injection molding process, and then joined together by welding. As yet another alternative, each of the portions 34 and 36 may be formed by molding two mating parts that are welded together, and then welding the portions 34 and 36 together.
After block 106, process 100 may proceed to block 108 in which the EGR tube 20 may be inserted into the lower shell 18. This step may include inserting the EGR tube 20 such that the first portion 34 is inserted into the first channel 40, and the second portion 36 sits in the lower portion 46 of the second channel 42. Where the EGR tube 20 includes tabs 48 extending from the second portion 36, this step may further include inserting the tabs 48 into grooves 50 of ridges 52, and further joining the tabs 48 with the grooves 50 and/or the ridges 52, for example, by welding, friction welding, or soldering.
After block 108, process 100 may proceed to block 110 in which the upper shell 16 may be attached to the lower shell 18, thereby enclosing the EGR tube 20 within the upper manifold 12. The upper shell 16 and the lower shell 18 may be attached by any mechanism, including, but not limited to fasteners, and/or processes, including, but not limited to, welding.
After block 110, process 100 may proceed to block 112 in which the upper manifold 12 may be attached to a lower manifold 14. The upper manifold 12 and the lower manifold 14 may similarly be attached by any mechanism, including, but not limited to fasteners, and/or processes, including, but not limited to, welding. A collar 26 may be provided to connect the first portion 34 of the EGR tube 20 with an exhaust gas conduit 24 of the manifold 14. Process 100 may end after block 110.
With regard to the processes, systems, methods, heuristics, etc. described herein, it should be understood that, although the steps of such processes, etc. have been described as occurring according to a certain ordered sequence, such processes could be practiced with the described steps performed in an order other than the order described herein. It further should be understood that certain steps could be performed simultaneously, that other steps could be added, or that certain steps described herein could be omitted. In other words, the descriptions of processes herein are provided for the purpose of illustrating certain embodiments, and should in no way be construed so as to limit the claimed invention.
Accordingly, it is to be understood that the above description is intended to be illustrative and not restrictive. Many embodiments and applications other than the examples provided would be upon reading the above description. The scope of the invention should be determined, not with reference to the above description, but should instead be determined with reference to the appended claims, along with the full scope of equivalents to which such claims are entitled. It is anticipated and intended that future developments will occur in the arts discussed herein, and that the disclosed systems and methods will be incorporated into such future embodiments. In sum, it should be understood that the invention is capable of modification and variation and is limited only by the following claims.
All terms used in the claims are intended to be given their broadest reasonable constructions and their ordinary meanings as understood by those skilled in the art unless an explicit indication to the contrary in made herein. In particular, use of the singular articles such as “a,” “the,” “said,” etc. should be read to recite one or more of the indicated elements unless a claim recites an explicit limitation to the contrary.
