Inertial supercharging effect

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The inertial supercharging effect is the increase of volumetric efficiency in the cylinder of an engine. [1]

Contents

Background

The internal combustion engine is the most common engine found in mechanical devices across the world.  The engine is powered by an air/gasoline mixture and the physics principles of heat and pressure.

Overview

Inertial supercharging effect is the result of incoming fuel/air charge developing momentum greater than intake stroke would generate alone. It is achieved by the careful design of the shape of the piston head, the valves and cam profile/valve timing which creates a vacuum that pulls more exhaust gases (and some of the intake gasses) out of the engine. This is immediately followed by a reflected pressure wave timed to force the extra intake gasses back into the cylinder, thus achieving a greater mass of air/fuel mix in the combustion chamber than possible with conventional methods. Expansion chambers only work well at a narrow engine speed range which is why two stroke engines are referred to as having a "powerband". Since the early 1980s exhaust powervalves have been developed which have the effect of altering the timing and/or volume of the expansion chamber, greatly improving the spread of power of high output two stroke engines. [2]

The idea behind this effect is that if more pressure is created within the cylinder, the faster the piston will be able to move. [1] The volumetric efficiency is maximized to increase the amount of air/fuel mixture in the cylinder during each cycle. [3] In turn, a greater air/fuel mixture in a cylinder will create a greater pressure therefore exerting a greater force on the piston.  This increased force on each individual piston increases the potential horsepower of the entire engine. [4] The timing of the opening and closing of the valves is essential to ensure the air in the cylinder is maximized to create the most power in each cycle. [5]

See also

Related Research Articles

<span class="mw-page-title-main">Compression ratio</span> Ratio of the volume of a combustion chamber from its largest capacity to its smallest capacity

The compression ratio is the ratio between the volume of the cylinder and combustion chamber in an internal combustion engine at their maximum and minimum values.

<span class="mw-page-title-main">Miller cycle</span> Thermodynamic cycle

In engineering, the Miller cycle is a thermodynamic cycle used in a type of internal combustion engine. The Miller cycle was patented by Ralph Miller, an American engineer, U.S. Patent 2,817,322 dated Dec 24, 1957. The engine may be two- or four-stroke and may be run on diesel fuel, gases, or dual fuel.

<span class="mw-page-title-main">Exhaust gas recirculation</span> NOx reduction technique used in gasoline and diesel engines

In internal combustion engines, exhaust gas recirculation (EGR) is a nitrogen oxide (NOx) emissions reduction technique used in petrol/gasoline, diesel engines and some hydrogen engines. EGR works by recirculating a portion of an engine's exhaust gas back to the engine cylinders. The exhaust gas displaces atmospheric air and reduces O2 in the combustion chamber. Reducing the amount of oxygen reduces the amount of fuel that can burn in the cylinder thereby reducing peak in-cylinder temperatures. The actual amount of recirculated exhaust gas varies with the engine operating parameters.

A stratified charge engine describes a certain type of internal combustion engine, usually spark ignition (SI) engine that can be used in trucks, automobiles, portable and stationary equipment. The term "stratified charge" refers to the working fluids and fuel vapors entering the cylinder. Usually the fuel is injected into the cylinder or enters as a fuel rich vapor where a spark or other means are used to initiate ignition where the fuel rich zone interacts with the air to promote complete combustion. A stratified charge can allow for slightly higher compression ratios without "knock," and leaner air/fuel ratio than in conventional internal combustion engines.

<span class="mw-page-title-main">Four-stroke engine</span> Internal combustion engine type

A four-strokeengine is an internal combustion (IC) engine in which the piston completes four separate strokes while turning the crankshaft. A stroke refers to the full travel of the piston along the cylinder, in either direction. The four separate strokes are termed:

  1. Intake: Also known as induction or suction. This stroke of the piston begins at top dead center (T.D.C.) and ends at bottom dead center (B.D.C.). In this stroke the intake valve must be in the open position while the piston pulls an air-fuel mixture into the cylinder by producing a partial vacuum in the cylinder through its downward motion.
  2. Compression: This stroke begins at B.D.C, or just at the end of the suction stroke, and ends at T.D.C. In this stroke the piston compresses the air-fuel mixture in preparation for ignition during the power stroke (below). Both the intake and exhaust valves are closed during this stage.
  3. Combustion: Also known as power or ignition. This is the start of the second revolution of the four stroke cycle. At this point the crankshaft has completed a full 360 degree revolution. While the piston is at T.D.C. the compressed air-fuel mixture is ignited by a spark plug or by heat generated by high compression, forcefully returning the piston to B.D.C. This stroke produces mechanical work from the engine to turn the crankshaft.
  4. Exhaust: Also known as outlet. During the exhaust stroke, the piston, once again, returns from B.D.C. to T.D.C. while the exhaust valve is open. This action expels the spent air-fuel mixture through the exhaust port.

A combustion chamber is part of an internal combustion engine in which the fuel/air mix is burned. For steam engines, the term has also been used for an extension of the firebox which is used to allow a more complete combustion process.

Volumetric efficiency (VE) in internal combustion engine engineering is defined as the ratio of the mass density of the air-fuel mixture drawn into the cylinder at atmospheric pressure to the mass density of the same volume of air in the intake manifold. The term is also used in other engineering contexts, such as hydraulic pumps and electronic components.

<span class="mw-page-title-main">Naturally aspirated engine</span> Type of internal combustion engine

A naturally aspirated engine, also known as a normally aspirated engine, and abbreviated to N/A or NA, is an internal combustion engine in which air intake depends solely on atmospheric pressure and does not have forced induction through a turbocharger or a supercharger.

<span class="mw-page-title-main">Inlet manifold</span> Automotive technology

In automotive engineering, an inlet manifold or intake manifold is the part of an engine that supplies the fuel/air mixture to the cylinders. The word manifold comes from the Old English word manigfeald and refers to the multiplying of one (pipe) into many.

Manifold vacuum, or engine vacuum in an internal combustion engine is the difference in air pressure between the engine's intake manifold and Earth's atmosphere.

The two-stroke power valve system is an improvement to a conventional two-stroke engine that gives a high power output over a wider RPM range.

In the context of an internal combustion engine, the term stroke has the following related meanings:

Cylinder head porting refers to the process of modifying the intake and exhaust ports of an internal combustion engine to improve their air flow. Cylinder heads, as manufactured, are usually suboptimal for racing applications due to being designed for maximum durability. Ports can be modified for maximum power, minimum fuel consumption, or a combination of the two, and the power delivery characteristics can be changed to suit a particular application.

<span class="mw-page-title-main">Ignition timing</span>

In a spark ignition internal combustion engine, ignition timing is the timing, relative to the current piston position and crankshaft angle, of the release of a spark in the combustion chamber near the end of the compression stroke.

<span class="mw-page-title-main">Supercharger</span> Air compressor for an internal combustion engine

In an internal combustion engine, a supercharger compresses the intake gas, forcing more air into the engine in order to produce more power for a given displacement.

The term six-stroke engine has been applied to a number of alternative internal combustion engine designs that attempt to improve on traditional two-stroke and four-stroke engines. Claimed advantages may include increased fuel efficiency, reduced mechanical complexity, and/or reduced emissions. These engines can be divided into two groups based on the number of pistons that contribute to the six strokes.

<span class="mw-page-title-main">Scavenging (engine)</span> Process used in internal combustion engines

Scavenging is the process of replacing the exhaust gas in a cylinder of an internal combustion engine with the fresh air/fuel mixture for the next cycle. If scavenging is incomplete, the remaining exhaust gases can cause improper combustion for the next cycle, leading to reduced power output.

<span class="mw-page-title-main">Two-stroke diesel engine</span> Engine type

A two-stroke diesel engine is a diesel engine that uses compression ignition in a two-stroke combustion cycle. It was invented by Hugo Güldner in 1899.

Internal combustion engines come in a wide variety of types, but have certain family resemblances, and thus share many common types of components.

<span class="mw-page-title-main">Internal combustion engine</span> Engine in which the combustion of a fuel occurs with an oxidizer in a combustion chamber

An internal combustion engine is a heat engine in which the combustion of a fuel occurs with an oxidizer in a combustion chamber that is an integral part of the working fluid flow circuit. In an internal combustion engine, the expansion of the high-temperature and high-pressure gases produced by combustion applies direct force to some component of the engine. The force is typically applied to pistons, turbine blades, a rotor, or a nozzle. This force moves the component over a distance, transforming chemical energy into kinetic energy which is used to propel, move or power whatever the engine is attached to.

References

  1. 1 2 "Inertia Supercharging Air Flow Optimization - Aircraft Engine Overhaul". www.victor-aviation.com. Retrieved 2019-03-25.
  2. ↑ P.W Performance Aust.
  3. ↑ Bohacz, Ray T. “Forced Induction .” Hemmings.com, May 2015, www.hemmings.com/magazine/hcc/2015/05/Forced-Induction/3748512.html.
  4. ↑ Hu, Bo; Turner, James WG; Akehurst, Sam; Brace, Chris; Copeland, Colin (March 2017). "Observations on and potential trends for mechanically supercharging a downsized passenger car engine:a review". Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering. 231 (4): 435–456. doi: 10.1177/0954407016636971 . ISSN   0954-4070.
  5. ↑ "Valve Timing Events and the Order of Importance". Engine Builder Magazine. 2016-04-15. Retrieved 2019-03-25.
  1. “Timing Is Everything .” Magnaflux Inspection - Aircraft Engine Overhaul, Victor Aviation Services, www.victor-aviation.com/Inertia_Supercharging_AirFlow_Optimization.ph
  2. Brain, Marshall, and Kristen Hall Geisler. “How Car Engines Work.” HowStuffWorks, 5 Apr. 2000, auto.howstuffworks.com/engine1.htm
  3. P.W. Performance Exhaust
  4. Bohacz, Ray T. “Forced Induction .” Hemmings.com, May 2015, www.hemmings.com/magazine/hcc/2015/05/Forced-Induction/3748512.html.
  5. Hu, Bo, et al. “Observations on and Potential Trends for Mechanically Supercharging a Downsized Passenger Car Engine:a Review.” Journal of Research in Crime and Delinquency, 6 Apr. 2016, journals.sagepub.com/doi/full/10.1177/0954407016636971.
  6. Kertes, Rick. “Valve Timing Events and the Order of Importance.” Engine Builder Magazine, 19 Apr. 2017, www.enginebuildermag.com/2016/04/valve-timing-events-and-the-order-of-importance/.
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