Power plants – Combustion products used as motive fluid – External-combustion engine type
Reexamination Certificate
1999-05-13
2001-04-17
Denion, Thomas (Department: 3748)
Power plants
Combustion products used as motive fluid
External-combustion engine type
C060S039600, C060S595000, C060S413000, C060S614000
Reexamination Certificate
active
06216444
ABSTRACT:
BACKGROUND OF THE INVENTION
The invention relates to a combustion engine with a combustion chamber which has an ignition device to burn a fuel accompanied by formation of a combustion gas during an explosion stroke. The combustion engine has a rigid wall which is displaceable by an expanding combustion gas and whose movement can be transmitted to a drive shaft.
Conventional combustion engines of this type are for example Otto engines and diesel engines or Stirling engines. With diesel engines and Otto engines, the combustion chamber is formed by a cylinder in which a piston is housed displaceably, which piston forms the rigid displaceable wall which is connected to a drive shaft.
Furthermore it is known from DE-OS 32 14 516 that the combustion gas generated in a combustion chamber, which is formed from a cylinder within which a piston is housed, is guided, after a first expansion and conversion into mechanical work, into a second cylinder with a piston housed therein for further expansion accompanied by further conversion into mechanical work.
SUMMARY OF THE INVENTION
The object of the invention is to increase the efficiency of a combustion engine of the type named previously, and this is achieved according to the invention in that the combustion chamber has a constant volume and a working chamber (also called pumping chamber) separate from the combustion chamber, but connected to the combustion chamber, is provided in order to convert the energy of the combustion gas into mechanical energy. The working chamber (or pumping chamber) has the displaceable rigid wall, and is preferably formed by a cylinder in which a piston is displaceably stored, which piston forms the displaceable rigid wall.
With conventional combustion engines of the type named previously, in which the displaceable wall is arranged directly in the combustion chamber, the combustion gas drawn off from the combustion chamber at the end of the explosion stroke is still under a relatively high above-atmospheric pressure. Because, within the combustion engine according to the invention, the combustion and conversion into mechanical work take place in different chambers, the energy inherent in the expanding work also takes place in different chambers. Thus, the energy inherent in the expanding combustion gas can largely be utilized. Advantageously, the pumping chamber (depending on, inter alia, the fuel used) can be designed so that at the end of the explosion stroke, when the end position of the displaceable wall is reached, the combustion gas is expanded to approximately atmospheric pressure.
Furthermore, the filling and the combustion process in the combustion chamber can be optimized so that no conversion of the energy of the combustion gas into mechanical driving energy of the engine takes place in the combustion chamber itself. Thus, the combustion chamber can, for example, in its shaping and in the arrangement of the ignition element, be optimally matched to the combustion process.
A pulsating recoil drive for water vehicles is known from WO 98/01338, in which the combustion gas formed in a combustion chamber is conducted into a pumping chamber filled with water, from which it expels the water by creation of a recoil. The pumping chamber of this combustion engine has no rigid displaceable wall, however, and instead forms a hydraulic element. Separate combustion and pumping chambers are used here because of the impossibility of filling the combustion chamber with water directly.
With the combustion engine according to the invention, an implosion stroke succeeding the explosion stroke is preferably provided in which the thermal energy of the expanded hot combustion gas is also to be at least partially utilized. To do this, a cooling medium is sprayed into the pumping chamber whereby the volume of the combustion gas reduces abruptly and a below-atmospheric pressure results which acts on the displaceable rigid wall of the pumping chamber.
With the combustion engine according to the invention, the feed lines or openings for fresh air and fuel, or for the mixture thereof, advantageously discharge exclusively into the combustion chamber, i.e. no such feed lines lead to the pumping chamber. The pumping chamber has advantageously only an exhaust gas outlet valve, and an overflow opening from the combustion chamber as gas inflow or gas outflow openings.
To achieve the highest possible efficiency and to minimize the resulting pollutants, the combustion chamber is advantageously filled with essentially constant charges of a combustible mixture (i.e. in contrast to conventional diesel or Otto engines, advantageously no charge-dependent filling of the combustion chamber is carried out). The ignition of the mixture takes place at a pressure of approx. 0.5 to 2 bar, preferably at approximately atmospheric pressure.
If the combustion engine according to the invention is for example to be used as a drive for a motor vehicle, it is proposed, in a first embodiment of the invention, in order to control the speed of the combustion engine, to connect to the drive shaft of the engine an infinitely variable, preferably hydrostatic transmission, whose function is explained in more detail in the description of the Figures. In a second embodiment of the invention, the power of the combustion engine is set such that, between work strokes in which ignitions of the mixture take place in the combustion chamber, idle strokes without such ignitions are interposed. In this case, a non-positive mechanical geared transmission can also be connected to the drive shaft, preferably via a clutch.
In a further embodiment, a hydraulic pumping device, which has at least one hydraulic-piston-cylinder unit, is driven directly by the piston of the pumping chamber without interpositioning of a crankshaft and rotating drive shaft. This hydraulic pumping device is designed to have an adjustable pumping volume and pressure, and it is therefore possible to use as a hydraulic engine driven by this hydraulic pumping device a non-adjustable hydraulic engine with a high degree of efficiency. As such a constant hydraulic engine, an inclined-disk piston engine which has an efficiency of &eegr;>0.9 in a large speed range, is particularly suitable. As hydraulic pumping devices based on piston cylinders also have a very high efficiency, overall an excellent total efficiency results.
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Denion Thomas
Trieu Thai-Ba
Wenderoth , Lind & Ponack, L.L.P.
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