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An arrangement for cooling of recirculating exhaust gases of an internal combustion engine

IP.com Disclosure Number: IPCOM000130593D
Publication Date: 2005-Oct-28
Document File: 2 page(s) / 39K

Publishing Venue

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Abstract

In internal combustion engines a technique called EGR is used to recirculate a certain amount of burned exhaust gases from a combustion process back into the engine, for the purpose to lower the temperature of the combustion and thereby reducing formation of oxides of nitrogen (NOX). The effect of EGR can be enhanced if the EGR-gases are cooled. According to this arrangement the exhaust gases are introduced in an EGR-cooler at an elevated pressure meaning that there is a higher temperature difference between the gases and the cooling media. This enables use of a cooler with relative small dimensions that facilitates mounting in spaces that are limited, and/or a more efficient cooling.

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An arrangement for cooling of recirculating exhaust gases of an internal combustion engine

By the technique called EGR (Exhaust Gas Recirculation), it is known to recirculate a certain amount of burned exhaust gases from a combustion process of an internal combustion engine back into the engine. As a consequence, a lower temperature of the combustion and a reduced formation of Oxides of Nitrogen (NOX) are obtained. However, an effective cooling of the exhaust gases reduces the amount of Oxides of Nitrogen further. Since the accessible space for components in a vehicle is very restricted, the use of larger EGR-coolers ought to be avoided.

The object of the invention is to provide an arrangement for cooling of the recirculating exhaust gases in an effective manner without using EGR-cooler with larger dimensions. This object is achieved by separating and recirculating a part of the exhaust gases having a higher pressure than an average pressure of the exhaust gases in the exhaust system. This high-pressure part of the exhaust gases also has a corresponding higher temperature than an average temperature of the exhaust gases in the exhaust system. By the use of such a part of the exhaust gases, an increased temperature difference ΔT is arisen between the recirculating exhaust gases and the cooling medium in the EGR-cooler. This results in a more effective cooling of the recirculating exhaust gases in the EGR-cooler. After the cooling process in the EGR-cooler, the recirculating exhaust gases are returned into the cylinders at an appropriate time after the inlet valves have been closed. According to the above, it is possible to cool the recirculating exhaust gases in a more effective manner than in a conventional EGR-cooler. Thereby, the formation of Oxides of Nitrogen (NOX) in the exhaust gases is reduced.

Fig. 1 shows an embodiment of an arrangement according to the invention. One cylinder 1 of a supercharged (turbocharged) internal combustion is shown in fig. 1. The cylinder 1 is provided with two intake valves 2a, b, one exhaust valves 3b and one valve 3a, which is controlled in a manner such that it works as an EGR-valve 3a. The exhaust...