Japanese automotive manufacturing company MAZDA has introduced new power units marked SKYACTIV-G.
These are petrol fuelled engines with spark ignition with increased compression ratio (1:14 in 2.0 l version and 1:13
in 2.5 l version). These engines are characterized by significantly better parameters and a reduction of combustion
of about 15%. Those who know what’s what know that in spark-ignition engines, the compression ratio higher than
about 1:10 (depending on the engine construction and shape of the combustion chamber) may not be used,
because if you use compression ratio higher than this value, detonation combustion effect occurs, which is
destructive for the engine.
How did MAZDA manage this problem? - I do not know that, but what I know is that on March 29, 1996, in Patent
Office of Poland I made a patent application number P-313550 called: ‘A Method of Conversion of Thermal Energy
into Mechanical Energy in Thermodynamic Engines’, here is a quotation from the abstract of the description: ‘A
High-Energy Method of Conversion of Thermal Energy into Mechanical Energy in Thermodynamic Engines, if used in
the spark ignition internal combustion engine, involves using a high compression ratio and fresh load admission
control whose appropriate mass is maintained at a wide range of engine speeds’. Now what is the essence of my
idea? It is possible to design spark ignition engines characterized by high energy efficiency. In order to achieve this,
increased compression ratio should be used with fresh load mass admission control expressed by a charging
efficiency. Following applying this solution, despite the high compression ratio, detonation ignition effect does not
occur, because during engine operation combustion chamber pressure does not exceed the value at which
detonation combustion occurs. With this project I was in 1996. in one of the automotive companies, but unfortunately
specialists of this factory reject my project. Description this patent application, and acknowledge and rejecting my
application decision of the Patent Office I put below. Of course, the application is before 17 years, at the moment I
developed them differently, please take into attention fact that, despite the fact that I had and am right, my knowledge
of thermodynamics at that time stood at a lower level than at present.
A Method of Conversion of Thermal Energy into
Mechanical Energy in Thermodynamic Engines
Field of the Invention. The object of the invention is a high-energy method of conversion of thermal energy into
mechanical energy in thermodynamic engines that allows to obtain energy efficiency of over 60%.
State of the Art. Methods for thermal energy conversion into mechanical energy in spark ignition internal combustion
engines, as well as in compression-ignition engines, known previously, can produce about 40% energy efficiency.
The Essence of the Method. The objective was to develop a method of engine operation characteristics which will
allow to obtain the energy efficiency exceeding 60%. In spark ignition engine this solution is obtained by applying high
compression ratio and fresh load admission controller which maintains the permanent mass of the load supplied to
the cylinder at a wide range of engine speeds. Mass of the load supplied to the cylinder is expressed by a charging
efficiency which in the method according to the invention is inversely proportional to the compression ratio and is
called the forced charging efficiency. So, if we assume that the most favourable compression ratio for spark ignition
engine is 1:9 proportion, and the engine according to the method, has the compression ratio of 1:23, then the most
favourable ratio of forced filling for this engine will be expressed by the quotient value of 9/23 f = 0.39 , which also in
the engine according to the method with a compression ratio of 1:23 will at the time of ignition allow to obtain
pressure corresponding to pressure obtained at the same time in a classic engine with compression ratio of 1:9.
Keeping this pressure during increasing engine speed in the classic naturally aspirated engine becomes impossible,
because the natural resistance of load filling increasing along with speed, makes pressure of the mixture at moment
of ignition getting smaller and smaller, and the combustion process slowing down. In the engine according to the
method, fresh load admission controller throttle, where clearance window increases with the rotational speed to full
throttle allows you to keep this pressure despite increasing engine speed. With full throttle, the natural load filling
resistance associated with the inlet channels construction give the charging efficiency equal to the forced charging
efficiency which is required for a given compression ratio. It should be noted here that with increasing engine speed,
when the speed of reciprocating piston movements increase, faster combustion of fuel-air mixture may be obtained
through the ignition angle timing, as well as by increasing the mass of the intake load which will allow to increase the
pressure of the mixture at the moment of ignition, while the gas pressure and ignition timing are adjusted to the
specific RPM in order to avoid the effect of detonation combustion. In the method according to the invention, the
cycles of engine operation are identical to those the currently applied in internal combustion engines, with valve
timing and ignition timing are adjusted to the engine operation characteristics.
The essential factors affecting the engine’s increasing energy efficiency according to the method, are:
- The ability to control the load pressure over a wide engine speed range, which has a beneficial effect on the
~ The possibility of total use of gas pressure increase as a result of heating.
Method according to the invention allows to construct high speed engines characterized by the following features:
- High energy efficiency.
- Low noise level during operation.
- Small amount of heat discharged into the coolant.
- Small amount of heat discharged with the exhaust gases.
- The low average operating temperature increases the lifetime of many components, and thus the engine itself.
- Very good mixture combustion.
- The distinctive engine operation that allows to eliminate the multi-stage gearboxes in vehicles.
- Ability to operate at low air pressure allows the engine to be widely used in the aviation industry.
- Compared with currently used engines half as big environmental contamination.
- Compared with currently used engines half as big operating cost.
Dynamics and energy efficiency of the engine according to the method was visualized in the drawings by
comparison with the classic engine, representing: Fig. 1 - The engine heat balance according to the method and the
classic engine. Fig. 2 - Tables with the approximate energy efficiency with respect to different compression ratio and
a corresponding forced charging efficiency. Fig. 3 - Diagram with the approximate torque characteristics for different
compression ratio from Fig. 2.