Power plants – Fluid motor means driven by waste heat or by exhaust energy... – With supercharging means for engine
Patent
1998-09-18
2000-04-18
Koczo, Michael
Power plants
Fluid motor means driven by waste heat or by exhaust energy...
With supercharging means for engine
60624, F02B 3904, F02M 2507
Patent
active
060500948
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The present invention relates to a supercharged internal combustion engine comprising firstly a turbocompressor unit with an exhaust driven turbo unit, which has an inlet communicating with the exhaust side of the engine, and a compressor unit, which has a suction side communicating with the surrounding atmosphere and a pressure side communicating with the engine intake side, and secondly an exhaust recirculation valve coupled between the exhaust side of the engine and the inlet of the turbo unit, said valve being settable for recirculation of a certain portion of the exhaust to the engine intake side.
DESCRIPTION OF THE RELATED ART
Exhaust can be returned to the intake side of a supercharged engine in essentially two different ways, each having different advantages and disadvantages, namely before or after the compressor. The simplest method technically would be to connect the recirculation line to the suction side of the compressor, but in that case the exhaust must pass through the compressor and then through the charge air cooler which is usually present. A significant disadvantage of this is however, that all the components would in time become coated with harmful soot from the exhaust. This disadvantage can be avoided by introducing the exhaust downstream of said components but if a turbo unit is used with the desired high efficiency, the charge air pressure will be higher than the exhaust pressure within the normal operating rpm range of the engine, which means that some form of pump device is desired which increases the exhaust pressure to a level above the charge air pressure. A supercharged engine with an exhaust pump in the form of an ejector pump is known by SE-A-9301093-2.
SUMMARY OF THE INVENTION
The purpose of the present invention is in general to achieve a supercharged internal combustion engine of the type described by way of introduction which permits return of exhaust to the intake side downstream of the compressor without requiring an exhaust pump. This is achieved according to the invention by virtue of the fact that the turbo unit and the compressor unit are so adapted to each other and to the engine that, within the normal operating speed range of the engine, the exhaust pressure on the inlet side of the turbo unit is higher than the charge air pressure on the pressure side of the compressor unit.
As regards design, this can be achieved with a turbocompressor which is dimensioned so that the pressure fall over the turbine will be greater than normal. A certain loss of efficiency in the turbo unit is in this case unavoidable.
In a preferred further development of the engine according to the invention, the turbo unit is coupled to the engine crank shaft via a reduction gearing and a continuously variable transmission. The loss which arises when redistributing the pressures can thus be recovered so that final result will be a net gain despite the increase in the exhaust pressure on the intake side of the turbo unit. An engine with these characteristic features thus fulfills three important conditions. By combining the setting of the degree of opening of the valve towards the engine intake side with a suitable setting of the rpm of the compressor with the aid of the continuously variable transmission, both the exhaust percent and the amount of air on the intake side can be freely controlled at each point on the operational curve of the engine at the same time as the compound arrangement permits exhaust return without any loss of efficiency.
BRIEF DESCRIPTION OF THE DRAWING
The invention will be described in more detail below with reference to examples shown in the accompanying drawing where the FIGURE shows schematically one embodiment of an engine installation with a six cylinder internal combustion engine.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
The engine 1 in the FIGURE can be a four stroke diesel engine. It shows a turbocompressor unit, generally designated 2, which comprises a turbo unit 3 and a compressor unit 4. The turbo unit 3 is conne
REFERENCES:
patent: 4803969 (1989-02-01), Hiereth et al.
patent: 5131229 (1992-07-01), Kriegler et al.
patent: 5729978 (1998-03-01), Hiereth et al.
Dahlgren Magnus
Udd Soren
AB Volvo
Koczo Michael
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