Hybrid cycle combustion engine and methods
An improved internal combustion engine of the four-stroke variable volume type operates by refraining from introducing substantial fuel into the working medium during the compression stroke until substantially maximum pressure of the working medium has been reached and utilizing at least one of the following processes: (a) causing combustion of fuel under substantially constant volume conditions; and (b) causing the power stroke to provide a larger volume to combustion products than the compression stroke provides to the working medium. Related methods are also provided.
1. A method of operating an internal combustion engine, of the type having a housing, a piston rotatably mounted in the housing and coupled to a shaft, and wherein occur phases of compression, combustion, and expansion in the housing, and wherein, in the compression phase, air introduced through an intake port into the housing is compressed by reducing volume of a compression chamber in the housing from an initial volume to a second volume that is less than the initial volume, and wherein the housing includes an exhaust port through which are passed gases resulting from combustion of fuel during the combustion phase, the method comprising:
providing a recess in the housing and configuring the piston so that, in the course of rotation of the piston, the piston at least in part covers the recess during the combustion phase to form a constant volume combustion chamber and during the expansion phase defines at least in part an expansion chamber volume that undergoes expansion of gases from combustion while the expansion chamber volume increases to a third volume that is larger than the initial volume;
introducing the fuel into the recess;
causing combustion, in the combustion phase, of the fuel that has been introduced into the combustion chamber, wherein reduction in volume during the compression phase, in combination with the introduction of the fuel, causes spontaneous combustion of the fuel; and
wherein the housing and the piston form, over the course of shaft rotation, the initial, second and third volumes in differing amounts for the phases of compression, combustion and expansion, in a manner that is smooth and continuous.
2. A method of operating an internal combustion engine according to claim 1 , further comprising using an energy recovery system to increase temperature of the fuel before it is introduced to the recess.
3. A method of operating an internal combustion engine according to claim 2 , further comprising using the energy recovery system to further reduce temperature of the gases from the combustion in the combustion phase.
4. A method of operating an internal combustion engine according to claim 2 , wherein using the energy recovery system further includes causing thermo-chemical decomposition of gaseous fuel.
5. A method of operating an internal combustion engine according to claim 2 , wherein using the energy recovery system further includes causing a catalyst-assisted reaction to occur at a temperature between about 450 degrees C. and about 750 degrees C.