Mtu Motoren-und Turbinen-union Friedrichshafen Gmbh

Dieter Schonfeld

Ralph-Michael Schmidt

Martin Freitag

Torsten Guth

Bernhard Bachle

Injection valves for liquid-fuel mixtures and associated processes

A process and a suitable arrangement for cooling diesel engine exhaust gases in an exhaust gas recirculation system is provided. In order to be able to avoid a contamination of the heat exchanger as well as a resulting required regenerating of the latter in the case of a cooling of the hot exhaust gas flow over a large temperature range, the cooling of the hot exhaust gas flow is carried out in at least two steps in that the exhaust gas flow flows successively through two heat exchangers which are each adapted to the corresponding cooling temperature range. By adapting the heat exchangers to specific small temperature ranges, even hot exhaust gas flows of up to 800.degree. C. can be cooled to a desired low temperature by the series connection of a corresponding number of different heat exchangers, without causing significant contaminations of the exhaust gas cooling arrangement by exhaust gas particles. By the use of known heat exchangers, the construction of the exhaust gas cooling system becomes particularly reasonable with respect to cost.

Process for cooling diesel engine exhaust gases

This invention relates to a two piece piston with a variable compression height, wherein a piston top part can be adjusted with respect to a piston bottom part along the longitudinal axis of the piston preferably by hydraulic devices and can be caused to perform a progressive rotating movement. This rotating movement is achieved by means of two thread sections of opposed pitch which, depending on the moving direction of the piston top part, alternately engage in corresponding counterthread sections on the piston bottom part. These threads and counterthreaded sections are multiple coarse pitch threads and are located on one side only as flanks disposed in the moving direction of the piston top part so that when the moving direction of the piston top part is reversed, a moving-apart of the engaged thread sections and counterthread sections occurs and the thread sections with an opposed pitch engage correspondingly on the flanks on the corresponding counterthread sections. In this case, either the thread sections assigned to the piston top part or the counterthread sections assigned to the piston bottom part are arranged offset with the respect to one another in the circumferential direction, by slightly less than the amount which corresponds to the rotation of the piston top part in the case of a certain stroke.

Growing community of inventors

Markdorf, Germany

Dieter Schonfeld