Achates Power

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Achates Power is an American developer of opposed-piston, two-stroke, compression ignition engines for use in commercial and passenger vehicles. Based in San Diego, California, the company was founded in 2004 by James U Lemke. [1]

Contents

According to Achates Power, its opposed-piston, two-stroke engine has demonstrated an increase in fuel efficiency and similar engine-out emissions levels. [2] [3] In 2014, the company published a technical paper citing a 30 percent fuel economy improvement when its engine was benchmarked against a next-generation diesel engine equipped with advanced technologies. [4]

In December 2012, the company announced that it had been selected as a subcontractor to AVL Powertrain Engineering, Inc. to build the next-generation combat engine for the U.S. Army. [5] Less than a year later, in October 2013, Achates Power and Fairbanks Morse Engine signed a joint development and licensing agreement to reduce emissions and fuel consumption of Fairbanks Morse proprietary and dual-fuel opposed-piston engines. [6]

Achates Power is privately owned and backed by Sequoia Capital, RockPort Capital Partners, Madrone Capital Partners, Triangle Peak Partners and Interwest Partners.[ citation needed ]

Engine

The Achates Power opposed-piston engine, is modeled after the opposed-piston architecture made popular by the Junkers Jumo 205/207 aviation engines developed in the 1930s. The design positions two pistons per cylinder—working in opposite, reciprocating motion. This eliminates parts including the cylinder head and valvetrain, improving overall engine efficiency as these components are considered primary contributors to heat and friction losses. [7] [8] The cylinder head and valvetrain systems are also among the most complex and costly elements of conventional engines. The two-stroke cycle compounds the efficiency benefits of the opposed-piston engine architecture. With this cycle, each combustion event is shorter in duration and, therefore, closer to optimum timing as compared to four-stroke engines. Two-stroke engines are also smaller in displacement and size compared to four-stroke engines for similar performance. [7]

While development of historic opposed-piston engines ceased for use in on-road car and truck applications with the introduction of modern emissions standards, [7] Achates Power says that it has patented many modifications to the original architecture [9] in order to meet current standards.

Emission reduction claims

Achates claims that its two-stroke opposed piston engine can achieve lower emissions of nitrogen oxides (NOx) than an equivalent four-stroke engine for several reasons. [10] For example:

Development Timeline

2004: Company founded by James Lemke with investment from the late John Walton, son of Sam Walton, the founder of Wal-Mart Stores, Inc.
2005: Engine testing begins at the company's in-house test cell
2007: Series A venture capital round led by Sequoia Capital with investments from RockPort Capital Partners, Madrone Capital Partners and InterWest Partners; company receives DARPA contract to design lightweight, compact UAV engine
2008: 500 hours of testing completed
2009: Second company test cell commissioned; Series B venture capital round led with new investor, Triangle Peak Partners
2010: Engine passes NATO 50-hour cyclic durability test; over 1,000 hours of testing completed; additional test stand added to company facility
2011: Over 2,500 hours of testing completed
2012: First firing of the company's A48 opposed-piston, double crank, spur gear train engine; company surpasses 3,600 hours of total test time; along with AVL Powertrain Engineering, Inc., Achates Power is selected by the U.S. Army to develop next-generation combat engine
2013: Achates Power selected for Frost & Sullivan 2013 North American New Product Innovation Award in the medium- and heavy-duty commercial vehicle engine market; company exceeds 4,500 hours of total test time; company named first runner-up in Securing America's Future Energy (SAFE) “Energy Security Prize”; Fairbanks Morse Engine signs joint development and licensing agreement with Achates Power
2014: Achates Power engine surpasses 5,000 hours of dynamometer testing; company releases results of light-duty diesel engine study comparing its engine to a next-generation diesel engine benchmark [11]

2015: The company is awarded a $14 million military contract by the U.S. Army Tank Automotive Research, Development and Engineering Center to help in the development of the Army's "future fighting vehicle" [12]

Related Research Articles

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

The diesel engine, named after 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 a so-called 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">Wankel engine</span> Combustion engine using an eccentric rotary design

The Wankel engine is a type of internal combustion engine using an eccentric rotary design to convert pressure into rotating motion.

<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 during one power cycle, this power cycle being completed in one revolution of the crankshaft. A four-stroke engine requires four strokes of the piston to complete a power cycle during 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">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 vacuum pressure into the cylinder through its downward motion. The piston is moving down as air is being sucked in by the downward motion against the piston.
  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 valve.
Napier Deltic Opposed-piston engine used in marine, firefighting and BR locomotive applications

The Napier Deltic engine is a British opposed-piston valveless, supercharged uniflow scavenged, two-stroke diesel engine used in marine and locomotive applications, designed and produced by D. Napier & Son. Unusually, the cylinders were disposed in a three-bank triangle, with a crankshaft at each corner of the triangle.

Opposed-piston engine Combustion engine using disks compressing fuel in the same cylinder

An opposed-piston engine is a piston engine in which each cylinder has a piston at both ends, and no cylinder head. Petrol and diesel opposed-piston engines have been used mostly in large-scale applications such as ships, military tanks, and factories. Current manufacturers of opposed-piston engines include Fairbanks-Morse, Cummins and Achates Power.

Homogeneous Charge Compression Ignition (HCCI) is a form of internal combustion in which well-mixed fuel and oxidizer are compressed to the point of auto-ignition. As in other forms of combustion, this exothermic reaction releases energy that can be transformed in an engine into work and heat.

Bourke engine Type of internal combustion 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, 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.

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">Free-piston engine</span>

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.

Brake-specific fuel consumption (BSFC) is a measure of the fuel efficiency of any prime mover that burns fuel and produces rotational, or shaft power. It is typically used for comparing the efficiency of internal combustion engines with a shaft output.

The Cummins X-series engine is an Inline (Straight)-6 diesel engine produced by Cummins for heavy duty trucks and motorcoaches, replacing the N14 in 2001 when emissions regulations passed by the EPA made the engine obsolete. Originally called the "Signature" series engine, the ISX uses the "Interact System" to further improve the engine. This engine is widely used in on highway and vocational trucks and is available in power ranging from 430 hp all the way to 620 hp 2050 lb-ft. The QSX is the off-highway version of the ISX with the Q standing for Quantum. The QSX is used for industrial, marine, oil & gas and other off-highway applications. Cummins also produced a 650 hp and 1950 lb-ft version for the RV market.

The Fairbanks-Morse 38 8-1/8 is a diesel engine of the two-stroke, opposed-piston type. It was developed in the 1930s, and is similar in arrangement to a contemporary series of German Junkers aircraft diesels. The engine was used extensively in US diesel electric submarines of the 1940s and 1950s, as backup power on most US nuclear submarines, as well as in other marine applications, stationary power generation, and briefly, locomotives. A slightly modified version, the 38ND 8-1/8, continues in service on Los Angeles-, Seawolf-, and Ohio-class nuclear submarines of the US Navy. The 38 8-1/8 has been in continuous production since its development in 1938, and is currently manufactured by a descendant of Fairbanks-Morse, FMDefense, in Beloit, Wisconsin.

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Squish (piston engine)

Squish is an effect in internal combustion engines which creates sudden turbulence of the air-fuel mixture as the piston approaches top dead centre (TDC).

<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. This replaced the external combustion engine for applications where the weight or size of an engine was more important.

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.

Partially premixed combustion (PPC), also known as PPCI or GDCI is a modern combustion process intended to be used in internal combustion engines of automobiles and other motorized vehicles in the future. Its high specific power, high fuel efficiency and low exhaust pollution have made it a promising technology. As a compression-ignition engine, the fuel mixture ignites due to the increase in temperature that occurs with compression rather than a spark from a spark plug. A PPC engine injects and premixes a charge during the compression stroke. This premixed charge is too lean to ignite during the compression stroke – the charge will ignite after the last fuel injection ends near TDC. The fuel efficiency and working principle of a PPC engine resemble those of Diesel engine, but the PPC engine can be run with a variety of fuels. Also, the partially premixed charge burns clean. Challenges with using gasoline in a PPC engine arise due to the low lubricity of gasoline and the low cetane value of gasoline. Use of fuel additives or gasoline-diesel or gasoline-biodiesel blends can mitigate the various problems with gasoline.

References

  1. ↑ "About Achates Power".
  2. ↑ Regner, G.; Callahan, B.; Dion, E.; Herold, R.; Johnson, D.; McIntyre, S.; Redon, F.; Wahl, M. (December 2011). "The Achates Power Opposed-Piston Two-Stroke Engine: Performance and Emissions Results in a Medium-Duty Application". SAE International Journal of Engines. 4 (3): 2726–2735. doi:10.4271/2011-01-2221. Archived from the original on 2013-04-15.
  3. ↑ Berg, Tom; Lockwood, Rolf; Park, Jim (January 12, 2012) “Engines Tomorrow: What Types of Engines Will You Be Selling Parts for in the Future?”, Heavy Duty Trucking
  4. ↑ Redon, F.; Kalebjian, C.; Kessler, J.; Rakovec, N.; Headley, J.; Regner, G.; Koszewnik, J. (2014). "Meeting Stringent 2025 Emissions and Fuel Efficiency Regulations with an Opposed-Piston, Light-Duty Diesel Engine". SAE Technical Paper Series. Vol. 1. PA: SAE International. doi:10.4271/2014-01-1187.
  5. ↑ Ponticel, Patrick (December 19, 2012) “U.S. Army tabs AVL and Achates Power for new-generation engine”, SAE Automotive Engineering International Online
  6. ↑ Zoia, David (January 2, 2014) “Achates Finding Traction with Opposed-Piston Engine”, WardsAuto.com
  7. 1 2 3 Flint, Martin; Pirault, Jean-Pierre (October 2009) Opposed Piston Engines – Evolution, Use and Future Applications, ISBN   978-0-7680-1800-4
  8. ↑ Foster, D.; Herold, R.; Lemke, J.; Regner, G.; Wahl, M. (2011). "Thermodynamic Benefits of Opposed-Piston Two-Stroke Engines". SAE Technical Paper Series. Vol. 1. PA: SAE International. doi:10.4271/2011-01-2216.
  9. ↑ "Home". patentdocs.org.
  10. ↑ "The Top Ten* Reasons the Opposed-Piston Engine is Naturally Low in NOx - *Updated with an 11th Reason". 27 July 2018.
  11. ↑ Achates Power Website. "Engine Design Timeline". Archived from the original on 2013-05-13.
  12. ↑ "Achates Power Wins $14 Million Military Engine Project". www.prnewswire.com. Retrieved 2015-11-05.
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