Two- and four-stroke engines

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Two- and four-stroke engines are engines that combine elements from both two-stroke and four-stroke engines. They usually incorporate two pistons.

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M4+2 engine

The M4+2 engine, also known as the double-piston internal combustion engine, is a type of internal combustion engine invented by Polish patent holder Piotr Mężyk. [1]

The M4+2 engine took its name from a combination of two-stroke engines and four-stroke engines. The two-stroke combustion engine is characterized by a simple construction and system of air load change, as well as a bigger index of power output. The cylinders of both modules of the double-pistons engine have been joined along one axis with a common cylinder head in the form of a ring. The pistons are moved at different speeds and with appropriate stage displacement. The two crankshafts are connected with a special transmission that rotates the four-stroke crankshaft at twice the speed of the two stroke crankshaft. In the M4+2, the advantages of both engines being connected are obvious; the pistons of the engine working in one combustion cylinder are set opposite to each other but in different modes. Opposed-piston engines have been tried before in both 2 stroke and 4 stroke, the combination of the two different cycles is unique to this engine. The engine has a far greater efficiency over the break-even value known to combustion engines (about 35%) and closer to the one associated with steam turbines or electric engines (about 70%).[ citation needed ]

The M4+2 prototype constructed at the Silesian University of Technology, Poland Proto.jpg
The M4+2 prototype constructed at the Silesian University of Technology, Poland

Advantages:

The idea was developed at the Silesian University of Technology, Poland, under the leadership of Adam Ciesiołkiewicz. [4] It was granted the patent number 195052 by the Polish Patent Office. [5] The work with the new combustion engine has been done by IZOLING P.W. Company in cooperation with the Silesian University of Technology in Gliwice. Consultations with researchers from Technical University of Kraków were also held. So far, two working engine models have been made. The preliminary model is based on two existing engines (a two-stroke motorbike engine and a four-stroke small machine engine). This model confirms the concept of two- and four-stroke engines' connection. The second model is the functional model. The new solution for a combustion engine was presented during scientific conferences (KONES '2002, Seminary of biofuels 2003, etc.) and in mass media (journals, newspapers, TVP, radio).

The M4+2 engine working cycle

The M4+2 engine working cycle animation M4+2anim.gif
The M4+2 engine working cycle animation

The stages of the working cycle:

The filling process takes place at the overpressure phase, using a mechanical gas compressor and a throttle for the purpose of regulation.

The load change is assisted by a four-stroke piston, working as a dynamic boosting system and allowing the good scavenging of working space.

A possibility exists of changing the relative piston positions during the engine work, which gives the possibility of changing the compression ratio depending on the temporary level of the load. This suggests the possibility of different fuels for combustion (low-octane petrol, biofuels with high levels of vegetable components).

The working cycle is characterized by an almost constant combustion characteristic of the working space volume increasing during the expansion stage. [6] [7]

The engine is characterized by:

Calculations prove the new engine has more favorable parameters and work indicators:

Ricardo 2x4 engine

The two-cycle modes are currently being researched at Ricardo Consulting Engineers in the UK. The concept consists in switching from one mode to the other depending on the rpm value. The four-stroke engine is more efficient when running at full throttle, while the opposite is the case for the two-stroke engine. When a small car under heavy load runs at half speed, the engine automatically switches to the two-cycle mode, which is then more efficient. The research on this showed a 27% reduction in fuel consumption. [8] [9]

The M4+2 engine has a four-stroke piston and a two-stroke piston. The shaft of the four-stroke piston rotates twice as fast as the shaft of the two-stroke piston, and the two-stroke part always runs at half speed. This ensures that both parts work optimally regarding fuel consumption at all times. The same principles apply to having two distinct engines, but the design of the M4+2 is much simpler.

See also

Related Research Articles

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The diesel engine, named after the German engineer Rudolf Diesel, is an internal combustion engine in which ignition of the fuel is caused by the elevated temperature of the air in the cylinder due to mechanical compression; thus, the diesel engine is called a compression-ignition engine. This contrasts with engines using spark plug-ignition of the air-fuel mixture, such as a petrol engine or a gas engine.

<span class="mw-page-title-main">Reciprocating engine</span> Engine utilising one or more reciprocating pistons

A reciprocating engine, also often known as a piston engine, is typically a heat engine that uses one or more reciprocating pistons to convert high temperature and high pressure into a rotating motion. This article describes the common features of all types. The main types are: the internal combustion engine, used extensively in motor vehicles; the steam engine, the mainstay of the Industrial Revolution; and the Stirling engine for niche applications. Internal combustion engines are further classified in two ways: either a spark-ignition (SI) engine, where the spark plug initiates the combustion; or a compression-ignition (CI) engine, where the air within the cylinder is compressed, thus heating it, so that the heated air ignites fuel that is injected then or earlier.

<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. It uses a supercharger or a turbocharger to offset the performance loss of the Atkinson cycle.

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

A two-strokeengine is a type of internal combustion engine that completes a power cycle with two strokes of the piston in one revolution of the crankshaft. In a two-stroke engine, the end of the combustion stroke and the beginning of the compression stroke happen simultaneously, with the intake and exhaust functions occurring at the same time.

<span class="mw-page-title-main">Otto cycle</span> Thermodynamic cycle for spark ignition piston engines

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

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

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<span class="mw-page-title-main">Dugald Clerk</span> Scottish engineer (1854–1932)

Sir Dugald Clerk KBE, LLD FRS was a Scottish engineer who designed the world's first successful two-stroke engine in 1878 and patented it in England in 1881. He was a graduate of Anderson's University in Glasgow, and Yorkshire College, Leeds. He formed the intellectual property firm with George Croydon Marks, called Marks & Clerk. He was knighted on 24 August 1917.

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

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The Bourke engine was an attempt by Russell Bourke, in the 1920s, to improve the two-stroke internal combustion engine. Despite finishing his design and building several working engines, the onset of World War II, lack of test results, and the poor health of his wife compounded to prevent his engine from ever coming successfully to market. The main claimed virtues of the design are that it has only two moving parts, is lightweight, has two power pulses per revolution, and does not need oil mixed into the fuel.

Variable compression ratio (VCR) is a technology to adjust the compression ratio of an internal combustion engine while the engine is in operation. This is done to increase fuel efficiency while under varying loads. Variable compression engines allow the volume above the piston at top dead centre to be changed. Higher loads require lower ratios to increase power, while lower loads need higher ratios to increase efficiency, i.e. to lower fuel consumption. For automotive use this needs to be done as the engine is running in response to the load and driving demands. The 2019 Infiniti QX50 is the first commercially available vehicle that uses a variable compression ratio engine.

<span class="mw-page-title-main">Hot-bulb engine</span> Internal combustion engine

The hot-bulb engine, also known as a semi-diesel or Akroyd engine, is a type of internal combustion engine in which fuel ignites by coming in contact with a red-hot metal surface inside a bulb, followed by the introduction of air (oxygen) compressed into the hot-bulb chamber by the rising piston. There is some ignition when the fuel is introduced, but it quickly uses up the available oxygen in the bulb. Vigorous ignition takes place only when sufficient oxygen is supplied to the hot-bulb chamber on the compression stroke of the engine.

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  1. Internal combustion and
  2. External combustion engines.

A six-stroke engine is one of several 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">Free-piston engine</span> Type of engine with no crank

A free-piston engine is a linear, 'crankless' internal combustion engine, in which the piston motion is not controlled by a crankshaft but determined by the interaction of forces from the combustion chamber gases, a rebound device and a load device.

<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.

<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. This process transforms chemical energy into kinetic energy which is used to propel, move or power whatever the engine is attached to.

The free-piston linear generator (FPLG) uses chemical energy from fuel to drive magnets through a stator and converts this linear motion into electric energy. Because of its versatility, low weight and high efficiency, it can be used in a wide range of applications, although it is of special interest to the mobility industry as range extenders for electric vehicles.

References

  1. ↑ Double pistons internal combustion engine, Official site of the city of Myszków, Poland. (in Polish) Archived 2017-01-09 at the Wayback Machine
  2. ↑ Invenia New-generation various fuel forms internal combustion engine – a review from Spain. Archived 2008-03-25 at the Wayback Machine
  3. ↑ BBS A review from Germany. Archived 2009-01-29 at the Wayback Machine
  4. ↑ Journal of KONES Internal Combustion Engines 2002 No. 1-2 ISSN   1231-4005, the official Polish educational site[ dead link ]
  5. ↑ The Polish Patent Office newsletter (in Polish) Archived 2007-01-25 at the Wayback Machine
  6. ↑ The Academical Forum monthly A report published by a Polish academic monthly Forum Akademickie (in Polish)[ dead link ]
  7. ↑ "A report published by Polish popular science magazine Strefa NDW" (in Polish). Archived from the original on 2006-08-25.
  8. ↑ Engineer Online Stroke of genius The Engineer (UK magazine) [ dead link ]
  9. ↑ Nonelectric Hybrid Engines Technology Review/MIT A novel hybrid engine could slash fuel consumption[ dead link ]
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