Bourke engine

Last updated
Four-cylinder Bourke engine Bourke Engine four Cylinder-Color.png
Four-cylinder Bourke engine
Figure 2 from Patent US 2172670 A US2172670- Figure 2-Color.png
Figure 2 from Patent US 2172670 A
Figure 1 from Patent US 2172670 A US2172670-Figure 1-Color.png
Figure 1 from Patent US 2172670 A
Animation of a four-cylinder bourke engine Bourke - two stroke - four cylinder.gif
Animation of a four-cylinder bourke engine

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, [1] 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.

Contents

The Bourke engine is basically a two-stroke design, with one horizontally opposed piston assembly using two pistons that move in the same direction at the same time, so that their operations are 180 degrees out of phase. The pistons are connected to a Scotch yoke mechanism in place of the more usual crankshaft mechanism, thus the piston acceleration is perfectly sinusoidal. This causes the pistons to spend more time at top dead center than conventional engines. The incoming charge is compressed in a chamber under the pistons, as in a conventional crankcase-charged two-stroke engine. The connecting-rod seal prevents the fuel from contaminating the bottom-end lubricating oil.

Operation

The operating cycle is very similar to that of a current production spark ignition two-stroke with crankcase compression, with two modifications:

  1. The fuel is injected directly into the air as it moves through the transfer port.
  2. The engine is designed to run without using spark ignition once it is warmed up. This is known as auto-ignition or dieseling, and the air/fuel mixture starts to burn due to the high temperature of the compressed gas, and/or the presence of hot metal in the combustion chamber.

Design features

The following design features have been identified:

Mechanical features

Gas flow and thermodynamic features

Lubrication

Claimed and measured performance

Engineering critique of the Bourke engine

The Bourke Engine has some interesting features, but the extravagant claims [14] for its performance are unlikely to be borne out by real tests. Many of the claims are contradictory. [15]

  1. Seal friction from the seal between the air compressor chamber and the crankcase, against the connecting rod, will reduce the efficiency. [16]
  2. Efficiency will be reduced due to pumping losses, as the air charge is compressed and expanded twice but energy is only extracted for power in one of the expansions per piston stroke. [17] [18]
  3. Engine weight is likely to be high because it will have to be very strongly built to cope with the high peak pressures seen as a result of the rapid high temperature combustion. [19]
  4. Each piston pair is highly imbalanced as the two pistons move in the same direction at the same time, unlike in a boxer engine. [20] This will limit the speed range and hence the power of the engine, and increase its weight due to the strong construction necessary to react the high forces in the components. [21]
  5. High speed two-stroke engines tend to be inefficient compared with four-strokes because some of the intake charge escapes unburnt with the exhaust. [22]
  6. Use of excess air will reduce the torque available for a given engine size. [23]
  7. Forcing the exhaust out rapidly through small ports will incur a further efficiency loss. [24]
  8. Operating an internal combustion engine in detonation reduces efficiency due to heat lost from the combustion gases being scrubbed against the combustion chamber walls by the shock waves. [25]
  9. Emissions - although some tests have shown low emissions in some circumstances, these were not necessarily at full power. As the scavenge ratio (i.e. engine torque) is increased more HC and CO will be emitted. [26]
  10. Increased dwell time at TDC will allow more heat to be transferred to the cylinder walls, reducing the efficiency. [27]
  11. When running in auto-ignition mode the timing of the start of the burn is controlled by the operating state of the engine, rather than directly as in a spark ignition or diesel engine. As such it may be possible to optimize it for one operating condition, but not for the wide range of torques and speeds that an engine typically sees. The result will be reduced efficiency and higher emissions. [28]
  12. If the efficiency is high, then combustion temperatures must be high, as required by the Carnot cycle, and the air fuel mixture must be lean. High combustion temperatures and lean mixtures cause nitrogen dioxide to be formed.

Patents

Russell Bourke obtained British and Canadian patents for the engine in 1939: GB514842 [29] and CA381959. [30]

He also obtained U.S. patent 2,172,670 in 1939. [31]

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">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. A four-stroke engine requires four strokes of the piston to complete a power cycle in two crankshaft revolutions. 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">Aircraft engine</span> Engine designed for use in powered aircraft

An aircraft engine, often referred to as an aero engine, is the power component of an aircraft propulsion system. Aircraft using power components are referred to as powered flight. Most aircraft engines are either piston engines or gas turbines, although a few have been rocket powered and in recent years many small UAVs have used electric motors.

<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.
<span class="mw-page-title-main">Gnome Monosoupape</span> Type of aircraft rotary engine

The Monosoupape, was a rotary engine design first introduced in 1913 by Gnome Engine Company. It used a clever arrangement of internal transfer ports and a single pushrod-operated exhaust valve to replace the many moving parts found on more conventional rotary engines, and made the Monosoupape engines some of the most reliable of the era. British aircraft designer Thomas Sopwith described the Monosoupape as "one of the greatest single advances in aviation".

The GM Ecotec engine, also known by its codename L850, is a family of all-aluminium inline-four engines, displacing between 1.2 and 2.5 litres. Confusingly, the Ecotec name was also applied to both the Buick V6 Engine when used in Holden Vehicles, as well as the final DOHC derivatives of the previous GM Family II engine; the architecture was substantially re-engineered for this new Ecotec application produced since 2000. This engine family replaced the GM Family II engine, the GM 122 engine, the Saab H engine, and the Quad 4 engine. It is manufactured in multiple locations, to include Spring Hill Manufacturing, in Spring Hill, Tennessee, with engine blocks and cylinder heads cast at Saginaw Metal Casting Operations in Saginaw, Michigan.

<span class="mw-page-title-main">Chrysler LA engine</span> Reciprocating internal combustion engine

The LA engine is a family of overhead-valve small-block 90° V-configured gasoline engines built by Chrysler Corporation between 1964 and 2003. A replacement of the Chrysler A engine, they were factory-installed in passenger vehicles, trucks and vans, commercial vehicles, marine and industrial applications. Their combustion chambers are wedge-shaped, rather than polyspheric, as in the A engine, or hemispheric in the Chrysler Hemi. LA engines have the same 4.46 in (113 mm) bore spacing as the A engines.

<span class="mw-page-title-main">Gasoline direct injection</span> Mixture formation system

Gasoline direct injection (GDI), also known as petrol direct injection (PDI), is a mixture formation system for internal combustion engines that run on gasoline (petrol), where fuel is injected into the combustion chamber. This is distinct from manifold injection systems, which inject fuel into the intake manifold.

<span class="mw-page-title-main">Scotch yoke</span> Mechanism to convert between rotational and reciprocating motion

The Scotch yoke is a reciprocating motion mechanism, converting the linear motion of a slider into rotational motion, or vice versa. The piston or other reciprocating part is directly coupled to a sliding yoke with a slot that engages a pin on the rotating part. The location of the piston versus time is simple harmonic motion, i.e., a sine wave having constant amplitude and constant frequency, given a constant rotational speed.

<span class="mw-page-title-main">Honda F engine</span> Reciprocating internal combustion engine

The Honda F-Series engine was considered Honda's "big block" SOHC inline four, though lower production DOHC versions of the F-series were built. It features a solid iron or aluminum open deck cast iron sleeved block and aluminum/magnesium cylinder head.

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

The hot-bulb engine, also known as a semi-diesel, 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.

<span class="mw-page-title-main">Model engine</span>

A model engine is a small internal combustion engine typically used to power a radio-controlled aircraft, radio-controlled car, radio-controlled boat, free flight, control line aircraft, or ground-running tether car model.

The term six-stroke engine has been applied to 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">Carbureted compression ignition model engine</span> Type of carbureted engine

A carbureted compression ignition model engine, popularly known as a model diesel engine, is a simple compression ignition engine made for model propulsion, usually model aircraft but also model boats. These are quite similar to the typical glow-plug engine that runs on a mixture of methanol-based fuels with a hot wire filament to provide ignition. Despite their name, their use of compression ignition, and the use of a kerosene fuel that is similar to diesel, model diesels share very little with full-size diesel engines.

<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. "War Department". Archived from the original on 2007-12-30. Retrieved 2008-01-13.
  2. The Most Powerful Diesel Engine in the World Archived July 16, 2010, at the Wayback Machine
  3. best two strokes
  4. Paul Niquette. "The Bourke Engine". Niquette.com. Retrieved 2011-12-06.
  5. GS Baker "Ship Form, Resistance, and Screw Propulsion" p215
  6. Sport Aviation March 1980 p 60 fig 18
  7. Sport Aviation March 1980 p 54
  8. Sport Aviation March 1980 p 54
  9. "Bourke Engine Com". Bourke-engine.com. Retrieved 2011-12-06.
  10. http://www.sportscardesigner.com/hp_per_lb.jpg HP per Lb. table (portscardesigner.com)
  11. "Unbenannt-1" (PDF). Archived from the original (PDF) on 2011-10-02. Retrieved 2011-12-06.
  12. "aircraft engine development". Pilotfriend.com. Retrieved 2011-12-06.
  13. The Bourke Engine Project L.L.C. - Confirmed Test Results Archived September 28, 2007, at the Wayback Machine
  14. Bourke Engine#Claimed and measured performance
  15. JB Heywood "Internal Combustion Engine Fundamentals" ISBN   0-07-100499-8 pp240-245|Trade-off between efficiency, emissions and power
  16. "Friction Forces in O-ring Sealing" (PDF). Archived from the original (PDF) on 2010-06-29. Retrieved 2007-12-16. |Friction of seals
  17. JB Heywood "Internal Combustion Engine Fundamentals" ISBN   0-07-100499-8 p723|Pumping losses
  18. C Feyette Taylor "The Internal Combustion Engine" 4th edition, p194 para 2-3, p205 fig 124b, p258|Pumping losses in two strokes
  19. C Feyette Taylor "The Internal Combustion Engine" 4th edition, p119|stresses due to detonation
  20. Engine balance#Single-cylinder engines Balance of single-cylinder engines
  21. JB Heywood "Internal Combustion Engine Fundamentals" ISBN   0-07-100499-8 p20|Importance of primary balance
  22. JB Heywood "Internal Combustion Engine Fundamentals" ISBN 0-07-100499-8 pp240-245, p881|Scavenging ratio and low efficiency
  23. JB Heywood "Internal Combustion Engine Fundamentals" ISBN   0-07-100499-8 pp240-245|Scavenging ratio effect on torque output
  24. C Feyette Taylor "The Internal Combustion Engine" 4th edition p194 para5|Pumping losses in two strokes
  25. JB Heywood "Internal Combustion Engine Fundamentals" ISBN   0-07-100499-8 p452-3|Increased thermal losses due to detonation
  26. JB Heywood "Internal Combustion Engine Fundamentals" ISBN 0-07-100499-8 pp240-245, p881|Scavenging ratio and high emissions
  27. "Science Links Japan | Effect of Piston Speed around Top Dead Center on Thermal Efficiency". Sciencelinks.jp. 2009-03-18. Archived from the original on 2012-01-27. Retrieved 2011-12-06.
  28. Hot bulb engine
  29. "Espacenet - Bibliographic data". Worldwide.espacenet.com. Retrieved 2013-01-21.
  30. "Espacenet - Bibliographic data". Worldwide.espacenet.com. Retrieved 2013-01-21.
  31. "Bourke".