INTERNAL COMBUSTION ENGINES
STATE OF THE ART OF THE ENGINE
Most commonly used type of internal combustion engine:
In-line engines are the designation of the design of a reciprocating piston engine,
the cylinders are in a row. In-line engines are by far the most common type of
internal combustion engine in cars, trucks, marine diesel engines (up to 14 cylinders)
and motorcycles. Four-cylinder in-line engines are most commonly used.
V-engine is a design of a reciprocating piston engine with several cylinders.
In the classic V-engine, the two cylinder banks stand against each other at the bank
angle on the crankcase below. After the in-line engine, it is the most widespread
Frictional losses in piston engines:
Otto engines have an efficiency between 20% and a maximum of 35%.
Based on 100 percent fuel energy in an Internal combustion engine, only around
30 percent of the energy from the engine is output as useful power via the crankshaft.
Frictional losses in the internal combustion engine reduce efficiency and have
a negative effect on consumption. An important lever against consumption in the
combustion engine is the minimization of friction.
The pure share of waste heat from engine friction is around 10 percent. The frictional
energy is lost as waste heat.
Frictional losses in internal combustion engines are caused by the vibratory motion of
pistons and valves and rotary motion in bearings. The friction losses between piston
and cylinder are greatest. A significant proportion of the friction losses is caused
by the plain bearings for connecting rods and crankshafts that are commonly used today.
As can be seen from the Stribeck curve, a hydrodynamic bearing passes
through the three stations of static or boundary friction, mixed friction and fluid
friction during operation.
Piston friction occurs on the contact surfaces between the piston rings and the cylinder bore
and between the piston skirt and the cylinder bore. A thin one forms on this contact surface
Oil film in which a shear stress is generated.
The mechanical losses in the motor amount to between 9% and 10% of the full load power and
are almost entirely dependent on the speed. The friction share of the piston group is
approx. 5% and that of the crankshaft approx. 3% of the losses. An important lever in the
combustion engine is the minimization of friction.
Since the internal combustion engine will continue to play a decisive role in the
future and under the pressure of ever stricter CO2 limits, the engine developers
optimize every component in terms of its friction in order to reduce fuel consumption.
The reduction of fuel consumption and CO2 emissions are and will remain the main
challenges for automobile manufacturers worldwide.
A reduction in the friction losses caused by the Sliding bearing and piston by 1%
(from 9% to 8% while the net power remains constant) increases the motor efficiency
by approx. 1 percentage points (e.g. from 30% to 31%) i.e. the increase in motor
efficiency is 3,3%. This leads to a reduction in fuel consumption and CO2 emissions.
The task is to develop a piston machine in which
1- The connecting rod should be moved if possible without deflection (close to its
cylinder axis), thereby reducing the lateral forces on the piston and reducing the
friction between the piston and the cylinder wall
2- the bearing friction of the connecting rod and the crankshaft should be reduced.
NEW PISTON MACHINE WITH ROCKER ARMS AND CRANK DRIVE
Inventor : Dr. Mustafa YOUSSEF
Applicant: Thermal PowerTec Ltd., Zurich/ Swizerland
A piston machine for use as a 4- or 2-stroke engine or as a working machine (compressor or pump)
consisting of a housing in which an even number of cylinders, preferably four cylinders,
which are arranged on two cylinder banks, have the same number of pistons (2) and piston
rod (3), an equilateral rocker arm (4), a crank connecting rod (5) and a crankshaft (12)
with a crank (11). A piston connecting rod (3) is connected to the piston on the one hand by
a piston pin (8) and on the other hand to the rocker arm (4). When the piston moves between
the top and bottom dead centre, the rocker arm performs a rotary oscillating movement. As
a result, the crank connecting rod (5) connected to the rocker arm (4) moves in a downward
and upward movement and causes the crank (11) and the crankshaft (12) to rotate.
Figures 1 to 3 show an example of the invention; a reciprocating piston engine with four
cylinders divided into two rows, according to the four-stroke process:
Another design for the connection of the rocker arm (4) with the crank connecting rod (5)
and the crank (11) is shown in Fig. 4. The rocker arm (4) has a third arm (15) which is arranged
obliquely or vertically and can be arranged below or above the axis of rotation of the
rocker arm (4). The crank connecting rod (5) connects the crank (11) with the arm (15) through
two bearings. The arm (15) rotates swinging with the rocker arm and, with the crank connecting
rod (5), brings the crank and the crankshaft in continuous rotary motion.
ADVANTAGES OF THE INVENTION
The new piston engine has the following advantages over the conventional 4-cylinder piston
- A reduction in the number of cranks in the crankshaft from four to one crank leads to less
construction costs for the crankshaft
- Reduction of the full rotation in several bearings to rotary oscillating with a small angle
of rotation (from 360 ° to ± 50 °)
- It is easier to change the type of contact from sliding to roller bearings
- The lateral piston forces on the cylinder walls are generated by a practically axial
movement of the piston connecting rod (3) with a small deflection (gama = 3 °)
- A reduction in the friction losses caused by the Sliding bearing and piston by 1%
(from 9% to 8%) increases the motor efficiency by approx. 1 percentage points (e.g.
from 30% to 31%) i.e. the increase in motor efficiency is 3.3%. This leads to
a reduction in fuel consumption and CO2 emissions.
- The radius of eccentricity of the crankshaft can be selected larger or smaller for a
certain piston stroke length