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HYBRID ENGINE
Fig. 1 1. INTRODUCTION In recent years, the research in the field of combustion engine for vehicles and stationary propulsive constructions have led a number of improvements which have opened new perspectives for such machines. Some of the latest improvements include fuel efficiency, pollution reduction, electronic ignition, fuel mixture cooling, direct fuel injection, variable stroke or compression ratio, air-fuel mixing and digital controlling of electromagnetic actuated intake/exhaust valves. All
these advancements have brought the engines some steps forward. However, they
are not sufficient to satisfy the present demanded various environmental laws so
that great efforts are necessary to meet even more severe regulation of the
future, especially the further reduction of the emissions concomitantly with the
fuel consumption. The concept described below tries to solve these problems
using an innovative piston engine arrangement. This concept is a four stroke
engine which can accept all the configurations of the actual four stroke engine
as in line, boxer (opposed pistons) or in V and can operate itself like a
hybrid, recovering the braking energy and the exhaust gases energy. Also this engine can be used as
primemover for the hybrid electric vehicles being cheap, powerful and simple. 2. CONCEPT AND DEVELOPMENT GOALS
The following goals were pursued in the
development of the hybrid engine concept: a) Throttless operation even as spark
ignition engine. b) Energy recovery. c) Reduction in friction loses. d) Similar or identical design of the
components reported to the classic four stroke engine and low development risks. e) Improved efficiency at all rpm but
specially at part loads. f) Improved power density to make the
engine more compatible with the increased weight of the hybrid vehicles.
g) Optimal combustion for
improved consumption and performances as well as reduced emissions. h) Application versatility
(automotive, aeronautical, nautical, spark ignition, diesel, etc.). i) High power density capability also
with alternative energy sources as GPL, natural gas, hydrogen and biofuels. j) Engine block modularity
allowing for a wide range of power options. k) Design simplicity excluding
the need for complex or expensive technology and precious materials. l) Compactness and reduced weight
allowing for easy assembly and maintenance. m) Reduction in wasted energy from the
exhaust. n) Improved durability combined with
improved performances. All these goals were taken into account in the concept of the hybrid engine and have been demonstrate the possibility to achieve small size engines having half cylinder number reported to the same power of a classic four stroke engine. If this engine is turbocharged the power density can be compared with the gas turbine engine level but this time with a very good efficiency.
3. SOLUTION DESCRIPTION
The supercharged engine uses mainly the same elements than a conventional four stroke engine configured in an innovative arrangement and adding an internal compressor placed between piston and crankshaft (Fig. 2).
Fig. 2 This internal
compressor is located in the crankcase but is completely isolated from the
oil pan. The supercharged internal combustion engine uses a solid piston
composed from a motor piston and compressor piston unified by a rod. The motor
piston works inside of a motor cylinder limiting the combustion chamber. The
compressor piston works inside of a compressor cylinder.
The compressor piston and the compressor cylinder have an oval form and
can be enclosed between two connecting rods which transmit the power to the
crankshaft. The compressor cylinder
is located inside a crankcase being closed by a wall. The wall contains few
inlet flexible valve and outlet flexible valve which work automatically like in
all the compressors.
Fig. 3 A plus is a dual power modality: it can use the pneumatic energy to act a lot of devices from the engine or vehicle. It is known that the pneumatic devices are chipper than hydraulic or electric acted mechanisms. Consequently the total price of the vehicle can be lower than actual. In
other configuration (Fig. 1) this concept can be utilized to achieve few hybrid
functions as the partial recovery of the braking energy or the stop and go
operation. The supercharged engine uses an internal compressor which, this
time, delivers all the compressed air directly into a main air tank. In this
case the combustion chamber is supplied with fresh air from the main air tank
when the intake valves are opened. If this supercharged engine is used to drive
a vehicle with mechanical or automatic transmission, when the driver needs to
slow down the vehicle, respectively the acceleration pedal is liberated or/and
the brake pedal are touched, the compressor piston is stressed at maximum to
compress the air in the main air tank. This effort is converted for the vehicle
in braking force. If
the driver needs more engine braking, he can change the transmission ratio in
the gear box and the braking effort is amplified by the increasing rotation
speed of the crankshaft. So, the brake energy is partially saved in the
compressed air form. Simultaneously with the engine brake the fuel supply system
of the engine is in “cut off” operation mode.
Fig. 4 3. ACTUAL STAGE OF THE DEVELOPMENT We created a virtual prototype to verify
the kinematics of the mechanism. The result: there are not kinematical problems.
4. ESTIMATED PARAMETERS In the table 1 are indicated the
estimated parameters for a 0.7 l passenger car engine achieved in different
variants with the proposed technology. It can observe that the maximum power and
torque are enough to drive passenger cars from the segments B, C and D
(subcompact, compact and middle class).
In the table 2 are also indicated the
estimated parameters for a 1.2 l passenger car engine. It can observe that the
maximum power and torque are enough to drive passenger cars from the segments E
and F (executive and luxury class cars) but also SUV’s or sport cars.
The fuel economy for a vehicle at constant speed can be estimated being around 20% for a spark ignition engine having same power level. The throttleless operation is difficult to be estimated but can improve the fuel economy with 2-3%. In city, the hybrid system becomes very important for the fuel economy and that depends by the traffic intensity. This system can recover up to 40% of the braking energy and also can use the stop and go operation. That means an estimated fuel economy being around 30% (depending on the traffic intensity) for both spark ignition or compression engines. The permanent exhaust gas recovery adds another 10% to the fuel efficiency. The reduction in CO2 emissions is proportional. Having so much power density and hybrid operation this concept can be used successfully in the powertrain of the future Formula 1 racing cars. With our proposed brake energy recovery the SPU (surge power units) can reach the maximum imposed weight of 20 Kg having an available energy capacity of some 900 KJ. In case of the hydrogen utilization, the engine configuration largely compensates the low energy density per unit volume specific of this fuel without any supplementary adaptation. A spark ignition variant supplied with hydrogen can reach an efficiency superior to 40%. Due to its small size, this engine can be located almost in any place, conferring to the automotive designer a great flexibility (Fig. 1). Fig. 1 5. ADVANTAGES OF THE CONCEPT -It is much smaller than
conventional four-stroke engine. This engine is employed in the vehicle for attaining
high efficiency for maximum power. The almost standard actual engine in four
cylinders can be easy replaced with the two cylinders engine. The size of the
engine is greatly reduced relative to the size of the vehicle in order to
minimize the effect of engine friction losses and to maximize vehicle fuel
economy. -The number of components of the proposed
two cylinders engine which replace the actual four cylinder engine is with at
least 25% smaller. Consequently the cost of this engine is significantly
less than the cost of the actual power source. -The throttleless operation of this engine
employed in a spark ignition configuration improves the efficiency at part loads
and simplifies the air intake system. -Adding a turbocharger and intercoolers the
high power density becomes very close with that obtained by the turbine engine
used in aviation. -This engine can work properly at high
altitude. In aviation that is a condition which is accomplished by the present
proposal. - Identical design of the components reported to the classic four stroke engine and consequently very low development risks. -Having
dual power, mechanic and pneumatic, it can easily act the auxiliary systems of
the engine or of the vehicle lowering the total cost. Also the pneumatic option
can be used to drive home or garage pneumatic tools without the acquisition of a
separate unit. 2) As hybrid engine for terrestrial
vehicles: -It is a key of the present invention to
achieve a significant reduction in fuel consumption by saving and storing the
energy of vehicle motion during its deceleration, and reusing it later
throughout its subsequent acceleration and propulsion. The stop and go function
completes this hybrid operation, obtaining big fuel economy in traffic
jam. -Compared with an electric hybrid system
the proposed solution eliminates the electric generator, motor and battery
components which are additional to the engine. This reduces cost, complexity,
weight and bulk while providing similar function and benefits. -By using partially regenerative braking
instead of friction braking it can reduce wear and increase durability of the
vehicle friction brakes. -The hybrid operation is used also in highway when a significant part of the exhaust gases energy is recovered.
3) As hydrogen engine: -It offers high
power density without any
supplementary adaptation. 6. CONCLUSION The
engine described before can be used as primemover for terrestrial, marine or
aerial vehicles as well as for the stationary constructions. Also this engine
can operate successfully in the powertrains of the hybrid vehicles because is
more simple, efficient and very important, cheaper than the conventional engine
associated or not with a hybrid electric transmission, having same level of
power and emissions. |
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