A STUDY ON SUITABILITY OF QUASITURBIBE ENGINES FOR NEW AGE CARS
Abstract:
The Quasiturbine is a pressure driven, continuous torque and symmetrically deformable spinning wheel. Excluding conventional turbines, the next step in the world of engine research is to make the gas engines as efficient as the diesel engines and the diesel engines as clean (or better) as the gas engines. Turbine characteristics help achieving this goal. The Quasiturbine is inspired by the turbine, perfects the piston and improves upon the Wankel engine, Efficient and compact. While current technologies adapt combustion processes to engine design, the Quasiturbine theory tends to adapt the engine design to combustion processes. It is a non-eccentric crankshaft, true rotary engine (no piston like movement), that uses a 4 face articulated rotor with a free and accessible center, rotating without vibration nor propulsive dead time and producing a strong torque at low RPM under a variety of modes and fuels. The Quasiturbine goes along the best modern engine development strategy, which is to get as many ignitions as possible per minute, with a mechanical device rotating as slowly as possible. Quasiturbine allows designs with up to « 7 conceptual degrees of freedom », substantially more than conventional turbine or piston engine, permitting to better shape the compression and relaxation volume pulse and further improved optimization. Taking full advantage of its unique short and fast linear ramp volume pulsed properties. It is a multi-fuel compatible (including direct hydrogen combustion), offers a drastic reduction in the overall propulsion system weight, size, maintenance and cost. Because Quasiturbine cycle is pressure driven instead of aerodynamically driven, it has a comparatively flat high efficiency characteristic in regard to RPM, load and power, which makes it most suitable for power modulation applications like in transportation and windmill energy storage and recovery systems. Used in Stirling and Brayton cycles, the Quasiturbine offers new ways to recover and transform thermal energy.
QUASITURBINE ENGINE PROTYTYPE
BASIC PARTS OF A QUASITURBINE ENGINE
Introduction
Engine design is at the confluence of three factors: concerns about how car emissions will affect the environment, rising gas prices and the need to conserve fossil fuel resources; and the realization that the hydrogen-powered car -- be it powered by a hydrogen fuel cell or by hydrogen internal combustion -- will not deliver on its promise in the near future. As a result, many engineers are giving more interest to improving the internal combustion engine.
While most rotary engines use the principle of volume variation between a curve and a moving cord, this new engine concept makes use of a "four degrees of freedom X, Y, q, ΓΈ" rotor, trapped inside an internal housing contour, and does not require a central shaft or support. The Quasiturbine is a concept which improves the conventional engines in 2 ways: in reducing the dead time, and in making better time management in the engine strokes.
The Quasiturbine looks like a rotary engine with a deformable rotor made of four identical blades, but because it has no crankshaft and does not follow sinusoidal motion, it has properties far different from the piston and the Wankel rotary piston engine. The Quasiturbine engine has been developed to simultaneously optimize the 14 important engine parameters, including compatibility with the revolutionary photo-detonation mode (knocking), which the piston engine cannot effectively tolerate. When taken together, these improvements increase fuel efficiency while simultaneously reducing exhaust emissions. Inspired by the turbine, it perfects the piston, and improves on the Wankel.
The Quasiturbine is a continuous flow engine at intake and exhaust. An engine's piston completes 4 strokes in two rotations, the Quasiturbine completes 32. Because it was conceived for thermal and photonic ignition, the Quasiturbine cannot be considered as a "rotary piston engine".
Quasiturbine engine is very efficient & less pollutant, compared to other engines available today.
Quasiturbine Basics
Like rotary engines, the Quasiturbine engine is based on a rotor-and-housing design. But instead of three blades, the Quasiturbine rotor has four elements chained together, with combustion chambers located between each element and the walls of the housing.
The four-sided rotor is what sets the Quasiturbine apart from the Wankel. There are actually two different ways to configure this design -- one with carriages and one without carriages.
OUTER SHELL TRACTION SLOT CARRIAGE
The Simple Quasiturbine Engine
The simpler Quasiturbine model looks very much like a traditional rotary engine. A rotor turns inside a nearly oval-shaped housing. Notice, however, that the Quasiturbine rotor has four elements instead of three. The sides of the rotor seal against the sides of the housing, and the corners of the rotor seal against the inner periphery, dividing it into four chambers.
In a piston engine, one complete four-stroke cycle produces two complete revolutions of the crankshaft. That means the power output of a piston engine is half a power stroke per one piston revolution.
In this basic model, it's very easy to see the four cycles of internal combustion:
Intake, which draws in a mixture of fuel and air
Compression, which squeezes the fuel-air mixture into a smaller volume
Combustion, which uses a spark from a spark plug to ignite the fuel
Exhaust, which expels waste gases (the byproducts of combustion) from the engine compartment
Quasiturbine engines with carriages work on the same basic idea as this simple design, with added design modifications that allow for photo-detonation. Photo-detonation is a superior combustion mode that requires more compression and greater sturdiness than piston or rotary engines can provide.
Photo-detonation
Photo Detonation is referred to as HCCI "Homogeneous Charge Compression Ignition".
| Four Types of Internal Combustion Engines | ||
|
| Homogenous Fuel-air Mixture | Heterogeneous Fuel-air Mixture |
| Spark-ignition | Type I
| Type II
|
| Pressure-heated Self-ignition | Type IV
| Type III
|
Type I - Includes engines in which the air and fuel mix thoroughly to form what is called a homogenous mixture. When a spark ignites the fuel, a hot flame sweeps through the mixture, burning the fuel as it goes. This, of course, is the gasoline engine.
Type II - A gasoline-direct injection engine -- uses partially mixed fuel and air (i.e., a heterogeneous mixture) that is injected directly into the cylinder rather than into an intake port. A spark plug then ignites the mixture, burning more of the fuel and creating less waste.
Type III - Air and fuel are only partially mixed in the combustion chamber. This heterogeneous mixture is then compressed, which causes the temperature to rise until self-ignition takes place. A diesel engine operates in this fashion.
Finally, in Type IV, the best attributes of gasoline and diesel engines are combined. A premixed fuel-air charge undergoes tremendous compression until the fuel self-ignites. This is what happens in a photo-detonation engine, and because it employs a homogenous charge and compression ignition, it is often described as an HCCI engine. HCCI (Homogeneous Charge Compression Ignition) combustion results in virtually no emissions and superior fuel efficiency. This is because photo-detonation engines completely combust the fuel, leaving behind no hydrocarbons to be treated by a catalytic converter or simply expelled into the air.
Of course, the high pressure required for photo-detonation puts a significant amount of stress on the engine itself. Piston engines can't withstand the violent force of the detonation. And traditional rotary engines such as the Wankel, which have longer combustion chambers that limit the amount of compression they can achieve, are incapable of producing the high-pressure environment necessary for photo-detonation to occur.
Enter the Quasiturbine with carriages. Only this design is strong enough and compact enough to withstand the force of photo-detonation and allow for the higher compression ratio necessary for pressure-heated self-ignition.
Advantages of Photo Detonation:
The HCCI engine is always un-throttled, a high compression ratio is used and the combustion is fast. This gives a high efficiency at low loads compared to a conventional engine that has low efficiency at part loads. If an HCCI engine is used instead of an ordinary gasoline engine in a car, the fuel consumption can be reduced to one half!
Another advantage is that the HCCI engine produces low amount of nitrogen-oxides (NOx). The formation of nitrogen-oxides is strongly dependent on combustion temperature. Higher temperature gives higher amount of NOx. Since the combustion is homogeneous and a very lean mixture is used the combustion temperature becomes very low, which results in very low amounts of NOx. The HCCI engine does not produce the same levels of soot as the Diesel engine.
The HCCI engine has much higher part load efficiency than the conventional engine and comparable to the Diesel engine, and has no problem with NOx and soot formation like the Diesel engine. In summary, the HCCI engine beats the conventional engine regarding the efficiency and the Diesel engine regarding the emissions.
Quasiturbine with Carriages
Even with its added complexity, the Quasiturbine engine with carriages has a relatively simple design. Each part is described below.
The housing (stator), which is a near oval known as the "Saint-Hilaire skating rink," forms the cavity in which the rotor rotates. The housing contains four ports:
A port where the spark plug normally sits (the spark plug can also be placed in the housing cover -- see below).
A port that is closed with a removable plug.
A port for the intake of air.
An exhaust port used to release the waste gases of combustion.
The housing is enclosed on each side by two covers. The covers have three ports of their own, allowing for maximum flexibility in how the engine is configured. For example, one port can serve as an intake from a conventional carburetor or be fitted with a gas or diesel injector, while another can serve as an alternate location for a spark plug. One of the three ports is a large outlet for exhaust gasses.
How the various ports are used depends on whether the automotive engineer wants a traditional internal combustion engine or one that delivers the super-high compression required of photo-detonation.
The rotor, made of four blades, replaces the pistons of a typical internal combustion engine. Each blade has a filler tip and traction slots to receive the coupling arms. A pivot forms the end of each blade. The job of the pivot is to join one blade to the next and to form a connection between the blade and the rocking carriages. There are four rocking carriages total, one for each blade. Each carriage is free to rotate around the same pivot so that it remains in contact with the inner wall of the housing at all times.
Each carriage works closely with two wheels, which means there are eight wheels altogether. The wheels enable the rotor to roll smoothly on the contoured surface of the housing wall and are made wide to reduce pressure at the point of contact.
The Quasiturbine engine doesn't need a central shaft to operate; but of course, a car requires an output shaft to transfer power from the engine to the wheels. The output shaft is connected to the rotor by two coupling arms, which fit into traction slots, and four arm braces.
When you put all of the parts together, the engine looks like this:
The Quasiturbine engine has none of the intricate parts of a typical piston engine. It has no crankshaft, valves, pistons, push rods, rockers or cams. And because the rotor blades "ride" on the carriages and wheels, there is little friction, which means oil and an oil pan are unnecessary.
In 1st step, as the rotor blades turns, change the volume of the chambers. First the volume increases, which allows the fuel-air mixture to expand. Then the volume decreases, which compresses the mixture into a smaller space.
The important feature is how one combustion stroke is ending right when the next combustion stroke is ready to fire. By making a small channel along the internal housing wall next to the spark plug, a small amount of hot gas is allowed to flow back to the next ready-to-fire combustion chamber when each of the carriage seals passes over the channel. The result is continuous combustion, just like in the airplane gas turbine!
What all this amounts to in the Quasiturbine engine is increased efficiency and performance. The four chambers produce two consecutive circuits. The first circuit is used to compress and expand during combustion. The second is used to expel exhaust and intake air. In one revolution of the rotor, four power strokes are created. That's eight times more than a typical piston engine! Even a Wankel engine, which produces three power strokes per rotor revolution, can't match the performance of a Quasiturbine.
Quasiturbine Advantages
Obviously, the increased power output of the Quasiturbine engine makes it superior to Wankel and piston engines, but it has also solved many of the problems presented by the Wankel.
For example, the Wankel engine leads to incomplete combustion of the fuel-air mixture, with the remaining unburned hydrocarbons released into the exhaust. The Quasiturbine engine overcomes this problem with a combustion chamber that is 30 percent less elongated. This means that the fuel-air mixture in the Quasiturbine experiences a greater compression and a more complete burn. It also means that, with less fuel going unburned, the Quasiturbine increases fuel efficiency dramatically.
Other significant advantages of the Quasiturbine include:
Zero vibration because the engine is perfectly balanced
Faster acceleration without a flywheel
Higher torque at lower rpm
Nearly oil-free operation
Less noise
Complete flexibility to operate completely submerged or in any orientation, even upside-down
Fewer moving parts for less wear and tear
Thermodynamics (advantage resulting from the early and late extraction of the mechanical energy).
Thermal (a flow of heat reduced towards the engine block).
Friction (the product "friction X displacement" is lower than that of the piston).
Accessories peripherals (a profit resulting from the absence of accessories: free of cams, valve...).
Power instantaneous peak (only 20% higher than the average, compared with 7 times for the piston).
Little harmonic on the shaft (no need for crankshaft, nor of flywheel).
Economy from absence of gearbox with fixed or multiple ratios (from 8 to 12 % of economy).
Economy in durability (measured in a number of passages, the low revolution means an increase in durability).
Effectiveness of intake (the piston has a poor sinusoidal intake characteristic).
Economy within application (a lighter vehicle... mean economies over 10 years!).
No additive in fuel (Quasiturbine asks for a less octane rate).
Environment (saving in fuel and less NOX product).
Vibration zero (source of billion $ of damage and corrosion).
Economy of space (4 times less than the piston engine).
Saving in weight (5 times less than the piston engine).
Quasiturbine improves each of these elements with several regards, mainly because it:
Has less driving accessories to actuate, not valve, tumbler, push rod, cams, pump oil...
Better management of time and offers a better operating time ratio to its components. At the time of the relaxation, Quasiturbine allows an earlier and later extraction of the mechanical energy.
Operation in continuous flow which improves the intake characteristic, which can to be even prolonged in the following cycle without fearing backpressure.
With a top engine torque at low revolution, the Quasiturbine does not need gear boxes with fixed or multiple ratios for the majority of the uses, meaning direct increases of the output, and an economy of consumption.
Finally, the Quasiturbine can run on different kinds of fuel, including methanol, gasoline, kerosene, natural gas and diesel. It can even accommodate hydrogen as a fuel source, making it an ideal transitional solution as cars evolve from traditional combustion to alternate fuels.
Typical comparison
Engine displacement Vs Total engine volume
| 4 strokes engine type | Unit displacement | Engine volume
|
| Piston | 1 | 15 to 20 |
| Wankel | 1 | 5 to 7 |
| Quasiturbine | 1 | 1.3 to 2 |
The Quasiturbine is a positive displacement turbine with a total displacement almost equal to the engine volume.
(Imagine one day, a 3 liters car engine into a 3 liters volume!)
CONCLUSION
Considering the modern internal combustion engine was invented by Karl Benz in 1886 and has enjoyed almost 120 years of design refinements, the Quasiturbine engine is still in its infancy. The engine is not used in any real-world applications that would test its suitability as a replacement for the piston engine (or the rotary engine, for that matter). It is still in its prototype phase the best look anyone has gotten so far is when it was demonstrated on a go-kart in 2004. The Quasiturbine may not be a competitive engine technology for decades.
In the future, however, you will likely see the Quasiturbine used in more than just your car. Because the central engine area is voluminous and requires no central shaft, it can accommodate generators, propellers and other output devices, making it an ideal engine to power bikes, cars, trucks, buses, & even chain saws, powered parachutes, snowmobiles, air compressors, ship propulsion systems and electric power plants.
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