Power plants – Fluid motor means driven by waste heat or by exhaust energy... – With supercharging means for engine
Reexamination Certificate
2000-04-17
2001-07-17
Nguyen, Hoang (Department: 3748)
Power plants
Fluid motor means driven by waste heat or by exhaust energy...
With supercharging means for engine
C060S605100, C415S042000, C415S045000
Reexamination Certificate
active
06260358
ABSTRACT:
BACKGROUND OF THE INVENTION
The invention relates to a multi-cylinder internal combustion engine with an exhaust-gas turbocharger and with at least two separate exhaust-gas lines to the turbine of the exhaust-gas turbocharger which are assigned to different cylinders or cylinder groups, and which can be joined ahead of the turbine or maintained separated depending on the operating condition of the engine.
In the case of supercharged internal combustion engines, in particular engines with an unfavourable ignition sequence, such as, for example, 8- or 5-cylinder engines, the charge exchange can be improved by feeding the turbine with separate exhaust-gas streams from different cylinders or cylinder groups. With pulse charging, in which, where appropriate, the exhaust gases from each cylinder are supplied individually to the turbine, interaction of the cylinders with one another is reduced or avoided. Some of the otherwise unusable expansion energy of the cylinders can be recovered by means of pulsed charging, whereby the transport of energy to the turbine is greatly improved. Particularly in the lower to medium load and speed range of the internal combustion engine, the delivery of air to the engine is assisted by the increased turbine power and the correspondingly increased compressor output of the exhaust-gas turbocharger. However, in the upper load range, for example above the medium speed of the internal combustion engine, conventional turbine designs will give rise, in the case of pulsed charging, to overcharging of the engine.
DE 32 00 521 C2 proposes an arrangement which provides two parallel exhaust-gas lines for conducting the exhaust gases to the turbine. The exhaust-gas lines have a connection upstream of the turbine and can be fluidically connected or they can be kept separated depending on the position of an actuator. The actuator is designed as a rotatable intermediate wall of the turbine inlet ports, having an axis of rotation coinciding with the turbine axis. The rotatable intermediate wall is controlled by a control unit and is brought into one of the end positions, as required, depending on the operating load. For pulsed charging in the lower partial load range, the exhaust-gas lines are separated, but they are in communication with one another in the other end position of the intermediate wall.
In the known device, in which the rotatable intermediate wall between two adjacent ports controls the fluidic communication or separation between the exhaust-gas streams from the cylinders to the turbine, effective pulsed charging and the change-over between the two charging methods available can not be achieved for multicylinder internal combustion engines, or only with a high structural outlay. Each pair of exhaust-gas lines has to have its own actuator, and the actuating movements of the various actuators must be synchronized.
It is the object of the present invention to provide on internal combustion engine, which, with a low structural outlay, permits communication between, or separation of, the exhaust-gas lines upstream of the turbine, as required.
SUMMARY OF THE INVENTION
In a multi-cylinder internal combustion engine including an exhaust gas turbocharger to which at least two separate exhaust lines extend from different groups of cylinders of the engine, the exhaust lines have discharge openings arranged adjacent one another along a control surface area and a control slide member supported so as to be movable relative to the exhaust gas discharge openings includes wall portion movable with the slide member between a position in which the wall portions of the slide member are in alignment with stationary wall portions between the discharge openings for maintaining the exhaust gas flow passages separated from one another and a position in which the wall portions on the slide member are out of alignment with the stationary wall portions, wherein the exhaust gas lines are in communication with one another.
According to the invention, the actuator for separating or joining the exhaust-gas lines is designed as a control slide structure, which includes wall portions of the exhaust-gas lines and is arranged in a region of the exhaust-gas lines in which the latter lie approximately in one plane one adjacent the other. When the control slide structure is in the closed position, the moveable wall portions are disposed adjacent the fixed wall portions of the exhaust-gas lines, which are thus fluidically separated from one another. For joining the exhaust-gas lines, the moveable wall portions are brought out of alignment with the containing line walls such that the adjacent the exhaust-gas lines are joined. In this case, by means of the slide according to the invention, all the exhaust-gas lines can be simultaneously interconnected, or if required, separated, in order to operate the internal combustion engine with pulsed charging.
Expediently, the control slide structure is arranged in the region of the openings of the exhaust-gas lines into the turbine and can thus be integrated into the turbine housing. The path of the exhaust-gas lines between the internal combustion engine and the exhaust-gas turbocharger is freely selectable and, even in the case of arrangements according to the invention in which each cylinder is to be assigned a separate exhaust-gas line, a small construction volume for the internal combustion engine can thus be achieved. The control slide structure may advantageously be designed to be axially and/or rotatably moveable.
In a preferred embodiment of the invention, the control slide structure is designed as a rotary slide which is in the form of an annular disc and which is arranged concentrically to the turbine axis. The openings of the exhaust-gas lines into the turbine housing in this case extend around the axis of rotation of the turbine in the form of a sector of a circle, the respective exhaust-gas streams flowing into the turbine approximately tangentially. In this case, the opening sectors of the exhaust-gas lines can be separated from, and connected to, one another by means of wall portions on the rotary slide. The opening sectors are advantageously arranged at equal circumferential angles around the turbine axis, adjacent exhaust-gas lines having a common wall portion in the region of the openings.
It is considered to be expedient if the control slide structure carries a projecting tongue for each exhaust-gas line, the said tongues being distributed uniformly over the circumference of the rotary slide. When the rotary slide is in the closed position for the purpose of pulsed charging, the tongues are in alignment with the common end portions of the walls of the exhaust-gas lines in the opening region, and the cylinder exhaust gases are thus guided individually in separate streams into the turbine. In this case, the thickness of the tongues and the wall thickness of the common end portions of the exhaust-gas lines are approximately equal.
One or more passage orifices may be provided in the control slide structure in the regions between the tongues, the said orifice or orifices lying radially adjacent an entrance, of the discharge line for exhaust gases covered by the rotary slide. In this case, the passage orifice can be brought into overlap with the entrance and interacts with the edge of the entrance like a valve. The discharge line can thus be controlled via the position of the control slide structure or, in the version, in which the actuating slide is a rotary slide, via the angular position of the rotary slide. The discharge line from the turbine housing expediently opens into the charge-air line downstream of the compressor of the exhaust-gas turbocharger and may be used for purposes of exhaust-gas recirculation or else for diverting charge air to the exhaust-gas tract of the internal combustion engine.
An exemplary embodiment of the invention is explained in greater detail below with reference to the drawing:
REFERENCES:
patent: 5454225 (1995-10-01), Sumser et al.
patent: 6073447 (2000-06-01), Kawakami et al.
patent: 31 45 835 (1983-
Daudel Helmut
Finger Helmut
Fledersbacher Peter
Sumser Siegfried
Bach Klaus J.
Daimler-Chrysler AG
Nguyen Hoang
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