Glow head motor

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Two clock -Glühkopfmotor : (1)  hot bulb , (2)  the combustion chamber , (3)  piston (4)  crankcase with overflow channel , the left and the exhaust

The hot-head motor , originally known as the Akroyd motor after its inventor Herbert Akroyd Stuart or as the Hornsby-Akroyd motor after the first manufacturer Richard Hornsby & Sons from 1891 , is an internal combustion engine with internal mixture formation and low compression . This engine mostly works on the two-stroke principle with crankcase flushing. During the compression stroke, the fuel is injected onto the red-hot inner wall of the combustion chamber, which is designed as a glow head, i.e. it is not cooled, is red-hot during operation and connected to the cylinder through channels in the cylinder head. The fuel evaporates on the hot surface and ignites towards the end of the compression at top dead center . The problem here is the poor controllability of the ignition timing of the self-ignition , which limits both the compression ratio and the possible speed range (low elasticity ).

The first as a four-stroke engine produced Hornsby Akroyd engine and subsequent two-stroke -Glühkopfmotoren were especially robust construction for agricultural machinery , marine drives designed and stationary drives, with a relatively low speed , and thereby only a low power output per liter in a large displacement . Due to their low compression ratio , they only achieve moderate efficiency with correspondingly high fuel consumption .

In spite of this, glow-head motors were very successful because at the time they were a cost-effective alternative to the steam engines that were still widespread in this sector at the time, especially for small power generators and drives in industry and agriculture , and thus opened up numerous new fields of application that were far too large, complex and far too large for steam engines were expensive.

Even when smaller diesel engines appeared later, glow-head engines were able to hold their own for many decades (especially in the Lanz Bulldog agricultural tractor, which is very popular in Germany ), as their simple technology was inexpensive to produce and made low demands on the fuel's ignitability and knock resistance . Developed further to the direct-injection hot-head engine as a robust multi-fuel engine , they were built until around 1960.

Small glow-igniter motors with a similar functional principle are still used in model making today.

classification

The hot-head engine is a heat engine , especially a reciprocating engine . With regard to the classification between gasoline and diesel engines, the hot-head engine was sometimes referred to as a third type , as it combines features of both engine principles:

  • With the diesel engine , the hot-head engine shares the internal mixture formation and the lack of spark plugs, whereby the ignition of the fuel in the hot-head engine differs significantly from that of the diesel engine. In contrast to diesel engines, which work with compression ignition, the fuel in hot-head engines ignites using an ignition aid, the eponymous hot glow head. That is why a significantly lower compression ratio is sufficient for hot-head engines .
  • Another advantage over diesel engines is that, due to the evaporation of the fuel in the glow head, you do not have to rely on good atomization by the injection nozzle and thus high injection pressure in order to achieve an ignitable fuel-air mixture .

Use & history

The hot-head motor was invented by the Englishman Herbert Akroyd Stuart . The first patents date from 1886, but the most important patent is from 1890. From 1891, the first hot-head engines were manufactured by the English company Richard Hornsby & Sons in Grantham , which equipped locomotives with their Hornsby-Akroyd engine and, in 1896, their first locomotive .

The Hornsby-Akroyd engines were initially four-stroke engines , later glow-head engines were mainly two-stroke engines . Hot-bulb engines were manufactured with one or more cylinders and were built as marine engines for a long time, for example as auxiliary engines for smaller sailing ships. The Swedish manufacturer Bolinders Mekaniska Verkstad achieved 80% market share in motors for fishing boats in the 1920s.

Hornsby-Akroyd engine : 14 hp four-stroke single- cylinder hot-bulb engine (1905)
Video: 8 HP two-stroke petrol engine " Patent Fenix"
Video: 30 HP two-stroke petrol engine Pythagoras "Drott" , Norrtälje (1924)
2-cylinder two-stroke glow head motor 70 HP, max. 325 min −1 ( WH Allen & Sons , 1923)

Hot-head motors in agricultural machinery

Hornsby crawler tractor (1905)
Lanz Bulldog HL (Bj. 1928): 12 HP single-cylinder two-stroke glow head engine ; Displacement 6.2 L; Max. 4.3 km / h

The British company Richard Hornsby & Sons 1896 was the first to a farm tractor (15 kW), with its 20 hp Hornsby Aykroyd engine built, and in 1905 the first caterpillar tractor with hot bulb engine by the proven wheeled tractor with a chain drive ( crawlers ) was equipped.

The Russian company Mamin-Sibirjak built glow-head engines from 1903 and began to produce agricultural tractors from 1912 . In the same year, the Swedish company JV Svensons Motorfabrik in Augustendal also began producing motor plows with hot-bulb engines . In 1913, another Swedish manufacturer, Munktells Mekaniska Värkstads AB in Eskilstuna, came onto the market with a large, 8.3 tonne two-cylinder hot-bulb farm tractor.

The glow-head motor became known in Germany primarily through the Lanz Bulldog , which Heinrich Lanz AG in Mannheim produced from 1921 ( Lanz HL ). The poor combustion of this engine caused a problem in agriculture: Many a Lanz Bulldog is said to have set fire to fields and barns with flying sparks in the exhaust gases, which was solved with subsequently modified exhaust systems.

Replacement by diesel engines from 1930

From the end of the 1920s, glow-head engines were given an alternative in the form of small diesel engines with pre-chamber injection , which were more economical and increasingly cheaper. Nonetheless, tractors with hot-head engines as robust multi-fuel engines, at least in Germany, were further developed by Heinrich Lanz AG and built as direct-injection hot-head engines (also known as " half-diesel engines" ) until 1960.

Glühkopfmotoren were simple in design, had therefore low cost as the fuel economy fuel-efficient diesel engines and had lower requirements for ignition and anti-knock properties of the fuel. That is why they could be operated with the cheapest or just available fuels ( multi-fuel engine ): Even small ship engines could burn old engine oil in addition to heavy oil or even run on crude oil .

Glow igniter engines

In  model making , the so-called glow plug or glow igniter motors are used as miniature internal combustion engines with a capacity of up to about 30 cm³ , which work according to a similar functional principle.

Manufacturer of glow head motors

Known manufacturer of Glühkopfmotoren were Richard Hornsby & Sons , the Heinrich Lanz AG , Ursus (replica of the lance), Bolinder-Munktell , Schlüter , Landini or Pampa Bulldog .

Handling & operation

Lanz Bulldog D8506 (Bj. 1951): 35 hp 10.3 liter single-cylinder two-stroke medium pressure glow head engine

fuel

Glühkopfmotoren can with normal diesel fuel , with heavy oil , blubber , paraffin , with all vegetable oils and even with crude oil or tar oil are operated ( multi-fuel engine ).

Function of the glow head

The spherical antechamber, the actual glow head, is preheated and not actively cooled during operation. The fuel injected into the glow head evaporates, and the tangential connection channel to the cylinder ensures strong turbulence and evaporation during the compression stroke through the air flowing in. The low evaporation rate, however, it takes a long time until an ignitable fuel-air mixture is produced, which is very early injection of fuel (about 130 ° crank angle before top dead center , requires) much earlier than the diesel engine .

Preheating of the glow head "preheating"

Preheating the glow head with a blowtorch on a Lanz Bulldog

Before a cold glow head motor can be started, the glow head must be preheated using an external heater ( blowtorch ).

Alternatively, there are designs with a separate small petrol tank and a spark plug in the glow head, with which the engine can be started in petrol mode. Once the operating temperature has been reached, the system switches to heavy oil operation.

Due to the design, longer idle times are not possible because the glow head cools down due to the lack of additional heat, so that the engine stops. This cooling down can be delayed or prevented by the shape of the glow head (so-called ignition bag) and an injection nozzle with adjustable spray angle.

Reversing to reverse

In the case of two-stroke glow-head engines, the direction of rotation of the engine could be reversed ("reversing") so that the tractors did not need a gearbox with their own reverse gear (robust and simple, for example all early Lanz Bulldogs ). To do this, the speed has to be reduced so far that the engine almost comes to a standstill, and then accelerating at the right moment (with a little skill and a lot of practice) triggers a pre-ignition that throws the engine back in the compression stroke so that it continues to run in the opposite direction .

See also

Web links

Wiktionary: glow head motor  - explanations of meanings, word origins, synonyms, translations
Commons : Glow Head Motors  - Collection of images, videos, and audio files
Commons : Hornsby-Akroyd-Motor  - collection of pictures, videos and audio files
Commons : Hornsby Crawler Tractor  - Collection of pictures, videos and audio files
Commons : Hornsby & Sons  - collection of images, videos and audio files
Commons : Lanz Bulldog  - Collection of images, videos and audio files

Video clips

Individual evidence

  1. ↑ Friedrich Sass: History of the German internal combustion engine construction from 1860 to 1918. Springer, Berlin / Heidelberg 1962, ISBN 978-3-662-11843-6 , pp. 415-422
    “Diesel engine and Akroyd engine - when to use the Akroyd engine for the first time has used the term hot-bulb engine, is unsafe. " (p. 418)
  2. ↑ Friedrich Sass (Ed.), Ch. Bouché: Dubbels Taschenbuch für den Maschinenbau. 11th edition, Springer-Verlag Berlin, Göttingen, Heidelberg 1955, Volume II, page 123.
  3. ^ Heinrich Lanz Mannheim: The stationary local bulldog: Fixed heavy oil engines of 12 and 15 hp . ( Memento from March 26, 2019 in the Internet Archive )
  4. ^ Herbert Akroyd Stuart: Improvements in Engines Operated by the Explosion of Mixtures of Combustible Vapor or Gas and Air , British Patent No 7146, May 1890.
  5. ↑ a b O. Hedell: Från Munktells till Valtra - en 75-årig traktorepok , LRF Media, 2000.
  6. ↑ Lanz Bulldog: General - Spark catcher. Available at: Lanz Bulldog Homepage, accessed: February 8, 2018.
  7. ↑ Lanz tractors no longer arsonists in: Motor vehicle technology 3/1953, p. 93.
  8. ↑ Fire prevention leaflet of the Bavarian Insurance Chamber from 1939 ( Memento from May 1, 2016 in the Internet Archive )
  9. ↑ a b The economical Lanz Bulldog. ( Memento from August 11, 2016 in the Internet Archive ) Further development of the glow-head motor. VDI-Nachrichten special edition from November 15, 1952 (PDF, 4 pages, 2.1 MB).
  10. ↑ Lanz Bulldog: Systematic overview of the Lanz types of glow-head Bulldogs from 1921–1945. available at Lanz Bulldog homepage, accessed: February 8, 2018.
  11. ↑ Lanz glow head technology. ( Memento from March 23, 2019 in the Internet Archive ) LANZ-Bulldog-Club-Holstein eV, archived: March 23, 2019.
  12. ↑ Patent DE938688 : Hot-head motor. Registered on May 31, 1952, published on February 2, 1956, applicant: Heinrich Lanz AG, inventor: Anton Lentz.
  13. ↑ Description of the engine in the Lanz Bulldog D 5006 (direct-injection glow-head "semi-diesel" engine).
  14. ↑ VDA : Heinrich Lanz Werk Mannheim - Type D 6007. Group 15, No. 450 (direct-injection hot-bulb "full diesel" engine). ( Memento from August 3, 2016 in the Internet Archive ) Frankfurt am Main, April 1956 (PDF 156 kB, archived on: August 3, 2016).
  15. ↑ Lanz semi-diesel technology. ( Memento from May 17, 2017 in the Internet Archive ) LANZ-Bulldog-Club-Holstein eV, lbch.de, archived: March 23, 2019.
  16. ↑ a b Lanz Bulldog: Fuel overview. Available at: Lanz Bulldog Homepage, accessed: February 8, 2018.
  17. ↑ Lanz glow head technology. ( Memento from March 23, 2019 in the Internet Archive ) Lanz Technik on: LANZ-Bulldog-Club-Holstein eV , ( Memento from August 4, 2018 in the Internet Archive ) archived: September 1, 2014.
  18. ↑ Lanz Bulldog: Instructions for using the blowtorch. Available at Lanz Bulldog Homepage, accessed: February 8, 2018.
  19. ↑ Lanz Bulldog: The starting process. Available at Lanz Bulldog Homepage, accessed: February 8, 2018.
  20. ↑ Lanz Bulldog: Starting the glow head motor. Available at: Lanz Bulldog Homepage, accessed: February 8, 2018.
  21. ↑ a b Lanz Bulldog: The glow head motor. Available at: Lanz Bulldog Homepage, accessed: February 8, 2018.
  22. ↑ Lanz Bulldog: Reverse gear by reversing the motor. October 14, 2012, topic = 41999, Forum Allrad · Oldtimer · LKW · Hanomag, etc., Allrad-LKW-Gemeinschaft.de.
  23. ↑ HL12 and the "reverse gear". ( Memento from March 16, 2019 in the Internet Archive ) www.lanzbulldog.de - Forum.