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A control system for an EGR-arrangement

IP.com Disclosure Number: IPCOM000019770D
Publication Date: 2003-Sep-29
Document File: 3 page(s) / 67K

Publishing Venue

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Abstract

Conventional EGR arrangements have a first valve for regulating the supply of recirculating exhaust gases to the engine and a second valve for regulating the supply of air to the engine. An electric control unit is arranged to control a first control valves for supplying a first control pressure to the first valve and a second control valve for supplying a second control pressure to the second valve. According to the invention, the first valve and the second valve are connected to one control valve in parallel, which control valve supplies one and the same control pressure to the first valve and the second valve. A condition for this invention is that the first valve and the second valve work within different range of pressures. According to the invention, a simple and reliable control system of an EGR arrangement is obtained including few components.

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A control system for an EGR arrangement.

By the technique called EGR (Exhaust Gas Recirculation), it is known to recirculate a part of the exhaust gases from a combustion engine to an inlet conduit supplying air to the internal combustion engine. In such a recirculation system, a mixture of air and exhaust gases is supplied to the cylinders of the engine. The supply of exhaust gases to the air results in a lower combustion temperature, which leads to a reduced quantity of nitrogen oxides NOX in the exhaust gases.

Conventional EGRarrangements have a first valve for regulating the supply of recirculating exhaust gases to the engine and a second valve for regulating the supply of air to the engine. An electric control unit is arranged to control a first control valves for supplying a first control pressure to the first valve and a second control valve for supplying a second control pressure to the second valve. According to the invention, the first valve and the second valve are connected to one control valve in parallel, which control valve supplies one and the same control pressure to the first valve and the second valve. A condition for this invention is that the first valve and the second valve work within different range of pressures. According to the invention, a simple and reliable control system of an EGRarrangement is obtained including few components.

In the attached Fig.1, a preferred embodiment of the invention is shown. Fig.1 shows an overcharged diesel engine 1, which may be a driving motor for a heavy vehicle. The exhaust gases from the diesel engine 1 is conducted, via an exhaust manifold 2, to the cylinders of an exhaust gas conduit 3. The exhaust gases is arranged to drive a turbine 4, before they are conducted away. The turbine 4 drives a compressor 5. The compressor 5 compresses the air in an inlet conduit 6. A cooler 7 is arranged in the inlet conduit 6 for cooling the compressed air. A return conduit 8 is intended to conduct exhaust gases from the exhaust gas conduit 3 to the inlet conduit 6.

The return conduit 8 comprises a first valve 9, which regulates the flow of the recirculating exhaust gases. The first valve 9 may be a seat valve or a throttle valve. The return conduit 8 comprises a cooler 10 for cooling the recirculating exhaust gases. In an overcharged diesel engine 1, the air in the inlet conduit 6 has a higher pressure than the exhaust gases. Therefore, a venturi 11 is used to overcome said pressure difference and mix the exhaust gases, from the return conduit 8, in the air in a first branched part of the inlet conduit 6’. The mixed composition is conducted to the respective cylinders of the diesel engine 1 via an inlet manifold 12. An air cylinder 13 is arranged to adjust a second valve 14, which is arranged to regulate the air flow in a second branched part of the inlet 6’’, which is arranged in parallel to the first branched part 6’. The second valve 14 may be a throttle vale. An electric control uni...