View source for Herbert Akroyd Stuart

{{short description|English engine design pioneer (1864–1927)}}
{{Use dmy dates|date=January 2017}}
{{Use British English|date=May 2021}}
[[File:Herbert Akroyd Stuart.jpg|thumb|250px|Herbert Akroyd Stuart (1864–1927) – Inventor of the hot bulb heavy oil engine]]
'''Herbert Akroyd-Stuart''' (28 January 1864 – 19 February 1927) was an English inventor who is noted for his invention of the [[hot bulb engine]], or [[heavy oil engine]].

==Life==
Akroyd-Stuart was born in [[Halifax, West Yorkshire|Halifax]], [[West Riding of Yorkshire|Yorkshire]], but lived in [[Australia]] for a period in his early years. He was educated at [[St. Bartholomew's School|Newbury Grammar School]] (now [[St. Bartholomew's School]]) and [[City and Guilds of London Institute|Finsbury Technical College]] in [[London]]. He was the son of Charles Stuart, founder of the Bletchley Iron and Tinplate Works, joining his father in the business in 1887.<ref>{{cite web
  | title = Victoria Road
  | publisher = Bletchley Archaeological & Historical Society
  | url = http://www.mkheritage.co.uk/bahs/fenny/victoria1.html
  | access-date = 29 July 2007 }}</ref>

==Oil engines==
In 1885, Akroyd Stuart accidentally spilt [[Kerosene|paraffin oil]] (kerosene) into a pot of molten [[tin]]. The paraffin oil vaporised and caught fire when in contact with a [[Kerosene lamp|paraffin lamp]]. This gave him an idea to pursue the possibility of using paraffin oil (very similar to modern-day [[Diesel fuel|diesel]]) for an engine, which unlike [[Gasoline|petrol]] proved difficult to vaporise in a carburettor because its [[Volatility (physics)|volatility]] is insufficient.

His first prototype engines were built in 1886. In 1890, in collaboration with Charles Richard Binney,  he filed Patent 7146 for [[Richard Hornsby & Sons|Richard Hornsby and Sons]] of [[Grantham]], [[Lincolnshire]], England. The patent was entitled: ''Improvements in Engines Operated by the Explosion of Mixtures of Combustible Vapour or Gas and Air''.<ref name="aoi">{{cite web
 |title=The Akroyd Oil Engine 
 |publisher=Ray Hooley's – Ruston-Hornsby – Engine Pages 
 |url=http://www.oldengine.org/members/ruston/History6.htm 
 |access-date=29 July 2007 
 |url-status=dead 
 |archive-url=https://web.archive.org/web/20110524213717/http://www.oldengine.org/members/ruston/History6.htm 
 |archive-date=24 May 2011 
 |df=dmy-all 
}}</ref> One such engine was sold to Newport Sanitary Authority, but the compression ratio was too low to get it started from cold, and it needed a heat poultice to get it going.<ref>{{cite web
 |title       = Diesel has come a long way but still doesn't get the tax breaks it deserves
 |work        = [[The Scotsman]], [[Scotland on Sunday]]
 |date        = 16 January 2003
 |url         = http://scotlandonsunday.scotsman.com/business.cfm?id=197272003
 |access-date  = 29 July 2007
 |url-status     = dead
 |archive-url  = https://archive.today/20120525002611/http://scotlandonsunday.scotsman.com/business.cfm?id=197272003
 |archive-date = 25 May 2012
 |df          = dmy-all
}}</ref>

=== Hornsby–Akroyd engine===
[[Image:Hornsby Akroyd lamp oil engine no.10171 of 1905 at GDSF 08.jpg|thumb|right|A Hornsby–Akroyd engine working at the [[Great Dorset Steam Fair]] ]]
Akroyd-Stuart's engines were built from 26 June 1891 by [[Richard Hornsby & Sons|Richard Hornsby and Sons]] as the ''Hornsby Akroyd Patent Oil Engine'' under licence and were first sold commercially on 8 July 1892. It was the first internal combustion engine to use a pressurised [[fuel injection]] system.<ref name=rwallis>{{cite book | last = Ransome-Wallis | first = Patrick | title = Illustrated Encyclopedia of World Railway Locomotives | publisher = Courier Dover Publications | year = 2001 | pages = 27 | isbn = 0-486-41247-4}}</ref>

The Hornsby–Akroyd engine used a comparatively low compression ratio, so that the temperature of the air compressed in the combustion chamber at the end of the compression stroke was not high enough to initiate combustion. Combustion instead took place in a separated combustion chamber, the ''vaporizer'' (also called the ''hot bulb'') mounted on the cylinder head, into which fuel was sprayed. It was connected to the cylinder by a narrow passage and was heated either by the cylinder's coolant or by exhaust gases while running; an external flame such as a blowtorch was used for starting. Self-ignition occurred from contact between the fuel-air mixture and the hot walls of the vaporizer.<ref name=mcneil>{{cite book | last = McNeil | first = Ian | title = An Encyclopaedia of the History of Technology | publisher = Taylor & Francis | year = 1990 | pages = [https://archive.org/details/encyclopaediaofh00mcne/page/310 310–311] | url = https://archive.org/details/encyclopaediaofh00mcne/page/310 | isbn = 0-415-01306-2 }}</ref> By contracting the bulb to a very narrow neck where it attached to the cylinder, a high degree of turbulence was set up as the ignited gases flashed through the neck into the cylinder, where combustion was completed. As the engine's load increased, so did the temperature of the bulb, causing the ignition period to advance; to counteract pre-ignition, water was dripped into the air intake.<ref name=wrangham>{{cite book | last = Wrangham | first = D.&nbsp;A. | title = The Theory & Practice of Heat Engines | publisher = Cambridge University Press | year = 1956 | pages = 664 }}</ref>

Hot bulb engines were produced until the late 1920s, often being called ''semi-diesels'', even though they were not as efficient as compression ignition engines. They had the advantage of comparative simplicity, since they did not require the air compressor used by early Diesel engines; fuel was injected mechanically (solid injection) near the start of the compression stroke, at a much lower pressure than that of Diesel engines.<ref name=mcneil/>

===Oil-engined locomotive===
Richard Hornsby and Sons built the world's first oil-engined [[railway locomotive]] [[Moirai|LACHESIS]] for the [[Royal Arsenal]], [[Woolwich]], England, in 1896. They also built the first compression-ignition powered automobile.

===Oil engines outside the UK===
;Sweden
Similar engines were built by Bolinder in [[Sweden]] and some of these still survive in [[narrowboat|canal boat]]s.

;United States
Hot bulb engines were built in the USA by the [http://baldwindiesels.railfan.net/magazine-1936/page20.html De La Vergne Company] of [[New York City]], later the New York Refrigerating Company – inventing the [[Vapor-compression refrigeration|modern refrigerator]] in 1930, who purchased a licence in 1893.

===Akroyd engine and Diesel engine===

[[Image:Herbert akroyd stuart plaque.jpg|thumb|right|Plaque in Denmark Street, [[Fenny Stratford]], UK, commemorating the work of Herbert Akroyd Stuart]]

Both the [[Diesel engine]] and the Akroyd engine run the same kind of fuel, [[petroleum oil]], which has led to a dispute about whether or not the Diesel engine is based upon the Akroyd engine.<ref name="Sass_420">Friedrich Sass: ''Geschichte des deutschen Verbrennungsmotorenbaus von 1860 bis 1918'', Springer, Berlin/Heidelberg 1962, {{ISBN|978-3-662-11843-6}}. p. 420</ref> The fact that the Diesel engine's operating principle differs from the operating principle [[Rudolf Diesel]] describes in his essay ''[[Theory and Construction of a Rational Heat Motor]]'' further contributed to this. The Akroyd engine was the first functional internal combustion engine that could use petroleum oil as fuel.<ref name="Sass_417">Friedrich Sass: ''Geschichte des deutschen Verbrennungsmotorenbaus von 1860 bis 1918'', Springer, Berlin/Heidelberg 1962, {{ISBN|978-3-662-11843-6}}. p. 417</ref> It was operational in 1891, six years before the Diesel engine first ran. However, after the Diesel engine had proven successful, ''Diesel engine'' became the synonym for an engine that ran on any sort of petroleum oil. ''Oil engines'' that used the Akroyd operating principle were called ''semi-Diesel'', and the name ''Akroyd'', which had been associated with oil engines, fell out of use. Therefore, Herbert Akroyd Stuart sought to replace the term Diesel engine with Akroyd engine in the early 20th century.<ref name="Sass_418">Friedrich Sass: ''Geschichte des deutschen Verbrennungsmotorenbaus von 1860 bis 1918'', Springer, Berlin/Heidelberg 1962, {{ISBN|978-3-662-11843-6}}. p. 418</ref>

Herbert Akroyd Stuart had two patents, No. 7146 ''Improvements in Engines Operated by the Explosion of Mixtures of Combustible Vapour or Gas and Air'', and No. 15994. In the former, the Akroyd engine's operating principle is described as follows: "... at the desired part of this compression stroke, the supply of liquid hydrocarbon is forced, in a spray form, on to the heated vaporiser, which almost instantly changes it into a gas...". Early Akroyd engines indeed operated on this principle.<ref name="Sass_417" /> Rudolf Diesel had a patent on the combustion process described in his essay (DRP 67207). The Diesel engine neither operates on the process described in the Akroyd patent, nor on the process described in the DRP 67207 patent. It operates instead on a different operating principle, also invented by Rudolf Diesel (patented in 1893, DRP 82168), which is why Diesel is in fact the Diesel engine's inventor. However, Diesel never admitted that his engine operated on a ''secret'' operating principle, and claimed that the Diesel engine operates on the (impossible) operating process described in the DRP 67207 patent.<ref>Friedrich Sass: ''Geschichte des deutschen Verbrennungsmotorenbaus von 1860 bis 1918'', Springer, Berlin/Heidelberg 1962, {{ISBN|978-3-662-11843-6}}. p. 517, 518</ref>

The key difference between the Akroyd and Diesel engines is the ignition: In an Akroyd engine, an ignition device{{dash}}the ''hot bulb'', or ''vaporiser''{{dash}}ignites the fuel, because the compression is too low for compression ignition (<300&nbsp;kPa). A Diesel engine on the other hand has no discrete ignition devices. The fuel instead ignites due to high heat caused solely by piston compression inside the cylinder (>3000&nbsp;kPa).<ref name="Sass_419">Friedrich Sass: ''Geschichte des deutschen Verbrennungsmotorenbaus von 1860 bis 1918'', Springer, Berlin/Heidelberg 1962, {{ISBN|978-3-662-11843-6}}. p. 419</ref> Since higher compression leads to better efficiency, the lower-pressure Akroyd engine consumes ~ 80% more fuel than a Diesel engine doing the same work.<ref name="Sass_416">Friedrich Sass: ''Geschichte des deutschen Verbrennungsmotorenbaus von 1860 bis 1918'', Springer, Berlin/Heidelberg 1962, {{ISBN|978-3-662-11843-6}}. p. 416</ref>

==Death==
{{unreferenced|section|date=May 2024}}
In 1900, he moved to Australia and set up a company Sanders & Stuart with his brother Charles. He died on 19 February 1927 in Perth, Australia of [[Esophageal cancer|throat cancer]]. His body was transported back to England and was buried in [[All Souls Church, Halifax|All Souls Cemetery]] in [[Akroydon|Boothtown]], [[Halifax, West Yorkshire|Halifax]], Yorkshire. All Souls Church was built at the sole expense of his maternal uncle, Edward Akroyd.

The [[University of Nottingham]] has hosted the Akroyd-Stuart Memorial Lecture on occasional years in his memory since 1928. One was presented by [[Frank Whittle|Sir Frank Whittle]] in 1946. Akroyd Stuart had worked with Professor William Robinson in the late 19th century, who was professor of engineering from 1890 to 1924 at University College Nottingham.

Akroyd-Stuart also left money to the [[Institution of Mechanical Engineers]], [[Royal Aeronautical Society]] and [[Institute of Marine Engineering, Science and Technology|Institute of Marine Engineering]], which provided for their respective bi-annual Akroyd-Stuart Prizes.

==See also==
*[[History of the internal combustion engine]]

==Notes==
{{reflist}}

==External links==
* [https://adb.anu.edu.au/biography/stuart-herbert-akroyd-8705 Biography]
* [https://web.archive.org/web/20110524213717/http://www.oldengine.org/members/ruston/History6.htm Relation to the Ruston and Hornsby history.]
* [http://www.enginemuseum.org/eoe.html History of his Oil Engine] {{Webarchive|url=https://web.archive.org/web/20091215100238/http://www.enginemuseum.org/eoe.html |date=15 December 2009 }} at the [[Anson Engine Museum]]
* [https://web.archive.org/web/20070202234054/http://users.ids.net/~newsm/oil.html De La Vergne Oil Engine used for Marconi's first broadcast]
* [http://www.imeche.org/industries/cef/prizeaward/Herbert-Akroyd-Stuart-Prize.htm IMechE Herbert Akroyd Prize (''sic'')]
* [http://www.ollerton.co.uk/products.php?id=16 Immortalised by naming a range of bollards after him]
* [https://web.archive.org/web/20070208050452/http://caldernet.org.uk/halifax/halifax_sites_and_sights/all_souls_church_halifax_.html All Souls Church, Halifax]

===Patents===
*
* [https://patents.google.com/patent/US845140 US Patent 845140] Combustion Engine, dated 26 February 1907.
* [https://patents.google.com/patent/US502837 US Patent 502837] Engine operated by the explosion of mixtures of gas or hydrocarbon vapor and air, dated 8 August 1893.
* [https://patents.google.com/patent/US439702 US Patent 439702] Petroleum Engine or Motor, dated 4 November 1890.

{{authority control}}

{{DEFAULTSORT:Stuart, Herbert Akroyd}}
[[Category:1864 births]]
[[Category:1927 deaths]]
[[Category:English mechanical engineers]]
[[Category:Stationary engines]]
[[Category:People associated with the internal combustion engine]]
[[Category:People from Halifax, West Yorkshire]]
[[Category:Academics of the University of Nottingham]]
[[Category:People educated at St. Bartholomew's School]]
[[Category:British people in colonial Australia]]