The
hotbulb, or
hot bulb engine or heavy oil engine is a type of
internal combustion engineThe internal combustion engine is an engine in which the combustion of a fuel occurs with an oxidizer in a combustion chamber. In an internal combustion engine the expansion of the high temperature and pressure gases, which are produced by the combustion, directly applies force to a movable...
. It is an engine in which
fuelFuel is any material that is burned or altered to obtain energy and to heat or to move object. Fuel releases its energy either through a chemical reaction means, such as combustion, or nuclear means, such as nuclear fission or nuclear fusion...
is
ignitedIgnition may refer to:*Making fire*Combustion*Ignition system, a method for activating and controlling the combustion of fuel in an internal combustion engine.* "Ignition" , a R&B/pop song by artist R...
by being brought into contact with a red hot metal surface inside a bulb.
Most hot bulb engines were produced as one cylinder low speed two stroke
crankcaseIn an internal combustion engine, the crankcase is the housing for the crankshaft. The enclosure forms the largest cavity in the engine and is located below the cylinder block....
scavengingScavenging is the process of pushing exhausted gas-charge out of the cylinder and drawing in a fresh draught of air ready for the next cycle in automotive usage. This process is essential in having a smooth-running internal combustion engine. Modifying the exhaust system, Scavenging is the process...
units.
History
The concept of this engine was established by
Herbert Akroyd StuartHerbert Akroyd-Stuart was an English inventor who is noted for his invention of the hot bulb engine, or heavy oil engine.-Life:...
at the end of the 19th century. The first prototypes were built in 1886 and production started in 1891 by
Richard Hornsby & SonsRichard Hornsby & Sons was an engine and machinery manufacturer in Lincolnshire, England from 1828 until 1918.-Formation:The company bearing the name of Richard Hornsby , the agricultural engineer, was founded when Richard opened a blacksmithy in Grantham, Lincolnshire in 1815 with Richard Seaman,...
of Grantham, Lincolnshire, England under the title Hornsby Akroyd Patent Oil Engine under licence.. It was later developed in the USA by the German emigrants Mietz and Weiss by combining it with the
two-strokeA two-stroke engine is a combustion engine that completes the thermodynamic cycle in two movements of the piston compared to twice that number for a four-stroke engine. This increased efficiency is accomplished by using the beginning of the compression stroke and the end of the combustion stroke to...
engine developed by
Joseph DayJoseph Day trained as an engineer at the School of Practical Engineering at Crystal Palace in London, began work at Stothert & Pitt in Bath, and in 1889 designed the two-stroke engine as it is widely-known today , the Valve-less Two-Stroke Engine...
. Similar engines, for agricultural and marine use, were built by
BolinderAB Bolinder-Munktell was a tractor and machines manufactorer founded in Eskilstuna, Sweden in 1932 through the merger of the mechanical companies Bolinder and Munktell. Bolinder was a large marine engine builder that had, in the 1920s, 80 percent of the world engine market.In 1950 BM was bought by...
and Pythagoras engine factory in Sweden. Bolinder is now part of the
VolvoThe Volvo Group is a Swedish supplier of commercial vehicles such as trucks, buses and construction equipment, drive systems for marine and industrial applications, aerospace components and financial services...
group.
Akroyd-Stuart's heavy oil engine (compared to
spark-ignitionThe term spark-ignition engine normally refers to internal combustion engines, specifically petrol engines, where the initiation of the combustion process of the air-fuel mixture is ignited within the combustion chamber by a spark from a spark plug...
) is distinctly different from
Rudolf Diesel'sRudolf Christian Karl Diesel was a European inventor and mechanical engineer, famous for the invention of the diesel engine.-Early life:...
better-known engine where ignition is initiated through the heat of compression. An oil engine will have a
compression ratioThe compression ratio of an internal-combustion engine or external combustion engine is a value that represents the ratio of the volume of its combustion chamber; from its largest capacity to its smallest capacity...
of about 3:1, where a typical
Diesel engineA diesel engine is an internal combustion engine that uses the heat of compression to initiate ignition to burn the fuel, which is injected into the combustion chamber during the final stage of compression...
will have a compression ratio ranging between 15:1 and 20:1. Furthermore fuel is injected
during the intake stroke and not at the end of the compression stroke as in a diesel.
Operation and working cycle
The hot-bulb engine shares its basic layout with nearly all other
internal combustion engineThe internal combustion engine is an engine in which the combustion of a fuel occurs with an oxidizer in a combustion chamber. In an internal combustion engine the expansion of the high temperature and pressure gases, which are produced by the combustion, directly applies force to a movable...
s, in that it has a
pistonA piston is a component of reciprocating engines, pumps and gas compressors. It is located in a cylinder and is made gas-tight by piston rings. In an engine, its purpose is to transfer force from expanding gas in the cylinder to the crankshaft via a piston rod and/or connecting rod...
inside a
cylinderA cylinder is the central working part of a reciprocating engine, the space in which a piston travels. Multiple cylinders are commonly arranged side by side in a bank, or engine block, which is typically cast from aluminum or cast iron before precision features are machined into it...
connected to a
flywheelA flywheel is a mechanical device with a significant moment of inertia used as a storage device for rotational energy. Flywheels resist changes in their rotational speed, which helps steady the rotation of the shaft when a fluctuating torque is exerted on it by its power source such as a...
via a connecting rod and
crankshaftThe crankshaft, sometimes casually abbreviated to crank, is the part of an engine which translates reciprocating linear piston motion into rotation...
. Akroyd-Stuart's original engine operated on the four-stroke cycle (Induction, Compression, Power, Exhaust) and
HornsbyRichard Hornsby & Sons was an engine and machinery manufacturer in Lincolnshire, England from 1828 until 1918.-Formation:The company bearing the name of Richard Hornsby , the agricultural engineer, was founded when Richard opened a blacksmithy in Grantham, Lincolnshire in 1815 with Richard Seaman,...
continued to build engines to this design, as did several other British manufacturers such as
Blackstone-Businesses:*Blackstone Group, U.S. private equity and asset management firm*Blackstone Career Institute, online training for paralegal, medical billing and coding, medical transcription, dental assistant, medical assistant and other studies...
and
CrossleyCrossley, based in Manchester, United Kingdom, was a pioneering company in the production of internal combustion engines. Since 1988 it has been part of the Rolls-Royce Power Engineering group.More than 100,000 Crossley oil and gas engines have been built....
. Manufacturers in
EuropeEurope is, by convention, one of the world's seven continents. Comprising the westernmost peninsula of Eurasia, Europe is generally divided from Asia to its east by the water divide of the Ural Mountains, the Ural River, the Caspian Sea, the Caucasus Mountains , and the Black Sea to the southeast...
,
ScandinaviaScandinavia is a geographical region in northern Europe that includes, and is named after, the Scanian Province. It consists of the kingdoms of Norway, Sweden, and Denmark...
and in the USA built engines working on the two- stroke cycle with crankcase scavenging. The latter type formed the majority of hot-bulb engine production. The flow of gases through the engine is controlled by valves in four-stroke engines, and by the piston covering and uncovering ports in the cylinder wall in two-strokes.
In the hot-bulb engine combustion took place in a separated combustion chamber, the "vaporizer" (also called the "hot bulb"), usually 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
blow-lampThe word blowtorch or blow torch has two meanings:In USA usage, it is what in British English usage is called a blowlamp, various types of liquid- or gas-burning tools used for heating...
or slow-burning wick was used for starting (on later models sometimes electric heating or pyrotechnics was used).
The pre-heating time depended on the engine design, the type of heating used and the ambient temperature, but generally ranged from 2–5 minutes for most engines in a temperate climate, to as much as half an hour if operating in extreme cold or the engine was especially large. The engine was then turned over, usually by hand but sometimes by compressed air or an electric motor.
Once the engine is running, the heat of compression and ignition maintains the hot-bulb at the necessary temperature and the blow-lamp or other heat source can be turned off. From this point the engine requires no external heat and requires only a supply of air, fuel oil and lubricating oil to run. However, under low power the bulb would cool off too much, and a throttle could cut down the cold fresh air supply. Also, 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.
The fact that the engine could be left unattended for long periods while running made hot bulb engines a popular choice for applications requiring a steady power output such as farm tractors,
generatorIn electricity generation, an electrical generator is a device that converts mechanical energy to electrical energy. The reverse conversion of electrical energy into mechanical energy is done by a motor; motors and generators have many similarities...
s,
pumpA pump is a device used to move fluids, such as gases, liquids or slurries. A pump displaces a volume by physical or mechanical action. One common misconception about pumps is the thought that they create pressure. Pumps alone do not create pressure; they only displace fluid, causing a flow. ...
s and
canalCanals are artificial channels for water. There are two types of canal: aqueduct canals are used for the conveyance and delivery of water, and waterway canals are navigable transportation canals used for passage of goods and people, often connected to existing lakes, rivers, or oceans.The word...
boat propulsion.
Four-stroke engines
Air is drawn into the cylinder through the intake valve as the piston descends (the induction stroke). During the same stroke, fuel is sprayed into the vaporizer by a mechanical (jerk-type) fuel pump through a nozzle. The air in the cylinder is then forced through the top of the cylinder as the piston rises (the compression stroke), through the opening into the vaporizer, where it is compressed and its temperature rises. The vaporized fuel mixes with the compressed air and ignites primarily due to the heat of the hot bulb generated while running, or heat applied to the hot-bulb prior to starting. By contracting the bulb to a very narrow neck where it attached to the cylinder, a high degree of turbulence is set up as the ignited gases flash through the neck into the cylinder, where combustion is completed. The resulting pressure drives the piston down (the power stroke). The piston's action is converted to a rotary motion by the crankshaft-flywheel assembly, to which equipment can be attached for work to be performed. The flywheel stores momentum, some of which is used to turn the engine when power is not being produced. The cycle then starts again.
Two-stroke engines
The cycle starts with the piston at the bottom of its stroke. As it rises, it draws air into the crankcase through the Inlet Port. At the same time fuel is sprayed into the vapouriser. The charge of air
on top of the piston is compressed into the vapouriser where it is mixed with the atomised fuel and ignites. The piston is driven down the cylinder. As it descends the piston first uncovers the Exhaust Port. The pressurised exhaust gases flow out of the cylinder. A fraction after the Exhaust Port is uncovered, the descending piston uncovers the Transfer Port. The piston is now pressurising the air in the crankcase, which is forced through the Transfer Port and into the space above the piston. Part of the incoming air charge is lost out the still-open Exhaust Port to ensure all the exhaust gases are cleared from the cylinder (a process known as 'scavenging'). The piston then reaches the bottom of its stroke and begins to rise again, drawing a fresh charge of air into the crankcase and completing the cycle. Induction and Compression are carried out on the upward stroke and Power and Exhaust on the downward stroke.
A supply of lubricating oil must be fed to the crankcase to supply the
crankshaftThe crankshaft, sometimes casually abbreviated to crank, is the part of an engine which translates reciprocating linear piston motion into rotation...
bearingsA bearing is a device to allow constrained relative motion between two or more parts, typically rotation or linear movement. Bearings may be classified broadly according to the motions they allow and according to their principle of operation as well as by the directions of applied loads they can...
. Since the crankcase is also used to supply air to the engine, the engine's lubricating oil is carried into the cylinder with the air charge, burnt during combustion and carried out the exhaust. The oil carried from the crankcase to the cylinder is used to lubricate the
pistonA piston is a component of reciprocating engines, pumps and gas compressors. It is located in a cylinder and is made gas-tight by piston rings. In an engine, its purpose is to transfer force from expanding gas in the cylinder to the crankshaft via a piston rod and/or connecting rod...
. This means that a 2-stroke hot-bulb engine will gradually burn its supply of lubricating oil- a design known as a 'total loss' lubricating system.
Advantages
At the time the hot-bulb engine was invented, its great attractions were its economy, simplicity, and ease of operation in comparison to the
steam engineA steam engine is a heat engine that performs mechanical work using steam as its working fluid.The idea of using boiling water to produce mechanical motion has a long history, going back about 2000 years...
, then the dominant source of power in industry. Steam engines achieved an average thermal efficiency (the percent of heat generated that is actually turned into useful work) of around 6%.
Hot-bulb engines could easily achieve 12% thermal efficiency.
During the period covering the 1910s–1950s, hot-bulb engines were more economical to manufacture with its low pressure crude fuel injection and low compression ratio than diesel engines .
The hot-bulb engine is much simpler to construct and operate than the steam engine. Boilers require at least one person to add water and fuel as needed and monitor pressure to prevent overpressure and a resulting explosion. If fitted with automatic lubrication systems and a
governorA governor, or speed limiter, is a device used to measure and regulate the speed of a machine, such as an engine. A classic example is the centrifugal governor, also known as the Watt or fly-ball governor, which uses weights mounted on spring-loaded arms to determine how fast a shaft is spinning,...
to control engine speed , a hot-bulb engine could be left running, unattended for hours at a time.
Another attraction was their safety. A steam engine, with its exposed fire and hot boiler, steam pipes and working cylinder could not be used in flammable conditions such as munitions factories or fuel refineries. Hot-bulb engines also produced cleaner exhaust fumes. A big danger with the steam engine was that if the boiler pressure grew too high and the safety valve failed, a highly dangerous explosion could occur (although this was a relatively rare occurrence by the time the hot-bulb engine was invented). A more common problem was that if the water level in the boiler of a steam engine dropped too low the lead plug in the crown of the furnace would melt, extinguishing the fire. If a hot bulb engine ran out of fuel, it would simply stop and could be immediately restarted with more fuel. The cooling water was usually a closed circuit, so no water loss would occur unless there was a leak. If the cooling water ran low, the engine would seize through overheating- a major problem, but it carried no danger of explosion.
Compared to both steam , gasoline (petrol) and diesel engines, hot-bulb engines are simpler and therefore have less potential problems. There is no electrical system as found on a petrol engine, and no external boiler and steam system as on a steam engine.
A big attraction with the hot-bulb engine was its ability to run on a wide range of fuels. Even poor-burning fuels could be used since a combination of vaporiser- and compression-ignition meant that such fuels could be made to combust. The usual fuel used was fuel oil, similar to modern-day diesel, but
natural gasNatural gas is a gas consisting primarily of methane. It is found associated with fossil fuels, in coal beds, as methane clathrates, and is created by methanogenic organisms in marshes, bogs, and landfills...
,
keroseneKerosene, sometimes spelled kerosine in scientific and industrial usage, also known as paraffin, is a combustible hydrocarbon liquid. The name is derived from Greek keros...
,
paraffinIn chemistry, paraffin is the common name for the alkane hydrocarbons with the general formula CnH2n+2. Paraffin wax refers to the solids with 20 ≤ n ≤ 40 ....
, crude oil, vegetable oil or
creosoteCreosote is the name used for a variety of products including wood creosote and coal tar creosote. Wood creosote is created by high temperature treatment of beech and other woods, or from the resin of the Creosote bush....
could also be used. This made the hot-bulb engine very cheap to run, since it could be run on cheaply available fuels. Some operators even ran engines on used engine oil, thus providing almost free power. Recently, this multi-fuel ability has led to an interest in using hot bulb engines in developing nations where they can be run on locally produced biofuel.
http://energy.saving.nu/biofuels/biofueldev.shtml
Due to the lengthy pre-heating time, hot-bulb engines were nearly always guaranteed to start quickly, even in extremely cold conditions. This made them popular choices in cold regions such as
CanadaCanada is a country occupying most of northern North America, extending from the Atlantic Ocean in the east to the Pacific Ocean in the west and northward into the Arctic Ocean...
and
ScandinaviaScandinavia is a geographical region in northern Europe that includes, and is named after, the Scanian Province. It consists of the kingdoms of Norway, Sweden, and Denmark...
, where steam engines were not viable and early gasoline and
diesel engineA diesel engine is an internal combustion engine that uses the heat of compression to initiate ignition to burn the fuel, which is injected into the combustion chamber during the final stage of compression...
s could not be relied on to operate.
Uses
The reliability of the hot-bulb engine, their ability to run on many fuels and the fact that they can be left running for hours or days at a time made them extremely popular with agricultural, forestry and marine users, where they were used for pumping and for powering milling, sawing and threshing machinery. Hot-bulb engines were also used on
road rollerA road roller is a compactor type engineering vehicle used to compact soil, gravel, concrete, or asphalt in the construction of roads and foundations....
s and
tractorA tractor is a vehicle specifically designed to deliver a high tractive effort at slow speeds, for the purposes of hauling a trailer or machinery used in agriculture or construction...
s.
J.V. Svensons Motorfabrik, i Augustendal in
Stockholm' is the capital and largest city of Sweden. It is the site of the national Swedish government, the Riksdag , and the official residence of the Swedish Monarch as well as the prime minister. The Monarch resides at Drottningholm Palace outside of Stockholm since 1980 and uses the Royal Palace of...
SwedenSweden , officially the Kingdom of Sweden , is a Nordic country on the Scandinavian Peninsula in Northern Europe...
used hot bulb engines in their Typ 1 motor plough, produced from 1912 to 1925. Munktells Mekaniska Verkstads AB, in
EskilstunaEskilstuna is a city and the seat of Eskilstuna Municipality, Södermanland County, Sweden with 60,185 inhabitants in 2005. Eskilstuna has a large Sweden Finn population....
,
SwedenSweden , officially the Kingdom of Sweden , is a Nordic country on the Scandinavian Peninsula in Northern Europe...
, produced agricultural tractors with hot bulb engines from 1913 onwards.
Heinrich Lanz Mannheim AG, in
MannheimMannheim is a city in Germany. With 327,318 inhabitants it is the second-largest city in the state of Baden-Württemberg after the capital Stuttgart....
,
GermanyGermany , officially the Federal Republic of Germany , is a country in Central Europe. It is bordered to the north by the North Sea, Denmark, and the Baltic Sea; to the east by Poland and the Czech Republic; to the south by Austria and Switzerland; and to the west by France, Luxembourg, Belgium,...
, started to use hot bulb engines in 1921, in the
Lanz BulldogThe Lanz Bulldog was a tractor manufactured by Heinrich Lanz AG in Mannheim, Baden-Württemberg, Germany. Production started in 1921 and various versions of the Bulldog were produced up to 1960. Deere & Company purchased Lanz in 1956 and started using the name "John Deere Lanz" for the Lanz product...
HL. Other well known tractor manufacturers that used bulb engines were Bubba, Gambino,
LandiniLandini SpA, headquartered in Fabbrico, Italy, was founded by Giovanni Landini in 1884 to produce agricultural equipment. Landini had just started making tractors in 1925 when Giovanni died preventing the completion of the first prototype tractor...
and
OrsiOrsi is a surname, and may refer to:* Adolfo Orsi* Clodomil Orsi* Fernando Orsi* Giuseppe Agostino Orsi* Hoover Orsi* John Orsi* Leigh Ann Orsi* Lelio Orsi* Raimundo Orsi...
in
ItalyItaly , officially the Italian Republic , is a country located on the Italian Peninsula in Southern Europe and on the two largest islands in the Mediterranean Sea, Sicily and Sardinia. Italy shares its northern, Alpine boundary with France, Switzerland, Austria and Slovenia...
, HSCS in
HungaryHungary , in English officially the Republic of Hungary , is a landlocked country in the Carpathian Basin of Central Europe, bordered by Austria, Slovakia, Ukraine, Romania, Serbia, Croatia, and Slovenia. Its capital is Budapest. Hungary is a member of OECD, NATO, EU, V4 and is a Schengen state...
, SFV in
FranceFrance , officially the French Republic , is a country located in Western Europe, with several overseas islands and territories located on other continents. Metropolitan France extends from the Mediterranean Sea to the English Channel and the North Sea, and from the Rhine to the Atlantic Ocean...
UrsusThe Ursus Factory is a Polish producer of agricultural machinery located at Warsaw.- Early History :The Ursus Factory was founded in Poland in 1893 on 15 Hay Street, Warsaw, by three engineers and four businessmen...
in
PolandPoland , officially the Republic of Poland , is a country in Central Europe . Poland is bordered by Germany to the west; the Czech Republic and Slovakia to the south; Ukraine, Belarus and Lithuania to the east; and the Baltic Sea and Kaliningrad Oblast, a Russian exclave, to the north...
, and
MarshallThe Field-Marshalls were a range of British farm tractors manufactured by Marshall, Sons & Co. of Gainsborough, Lincolnshire.Field-Marshalls were in production from 1945 to 1957, however, the first single-cylinder Marshall came into production in 1930....
in
EnglandEngland is a country that is part of the United Kingdom. It shares land borders with Scotland to the north and Wales to the west; the Irish Sea is to the north west, the Celtic Sea to the south west and the North Sea to the east, with the English Channel to the south separating it from continental...
.
At the start of the 20th century there were several hundreds of
EuropeEurope is, by convention, one of the world's seven continents. Comprising the westernmost peninsula of Eurasia, Europe is generally divided from Asia to its east by the water divide of the Ural Mountains, the Ural River, the Caspian Sea, the Caucasus Mountains , and the Black Sea to the southeast...
an manufacturers of hot bulb engines for marine use. In Sweden alone there were over 70 manufacturers, of which
BolinderAB Bolinder-Munktell was a tractor and machines manufactorer founded in Eskilstuna, Sweden in 1932 through the merger of the mechanical companies Bolinder and Munktell. Bolinder was a large marine engine builder that had, in the 1920s, 80 percent of the world engine market.In 1950 BM was bought by...
is the best known (in the 1920s they had about 80% of the world market). The
NorwegianNorway , officially the Kingdom of Norway, is a country in Northern Europe occupying the western portion of the Scandinavian Peninsula, as well as Jan Mayen and the Arctic archipelago of Svalbard under the Spitsbergen Treaty...
SABB was a very popular hot bulb engine for small fishing boats and many of them are still in working order. In America Standard, Weber, Reid, Stickney, Oil City, and Fairbanks Morse built hotbulb engines.
A limitation of the design of the engine was that it could only run over quite a narrow (and slow) speed band, typically 50-300 R.P.M.. This made the hot-bulb engine difficult to adapt to automotive uses other than vehicles such as tractors, where speed was not a major requirement. This limitation was of little consequence for stationary applications, where the hot-bulb engine was very popular.
Owing to the lengthy pre-heating time, hot-bulb engines only found favour with users who needed to run engines for long periods of time, where the pre-heating process only represented a small percentage of the overall running period. This included marine use (especially in fishing boats) and pumping/drainage duties.
The hot-bulb engine was invented at the same time that
dynamo-In Engineering:* Dynamo, a magnetic device originally used as an electric generator* Dynamo theory, a theory relating to magnetic fields of celestial bodies* Solar dynamo, the physical process that generates the Sun's magnetic field-Europe:...
s and
electric lightMost of the industrialized world is lit by electric lights, which are used both at night and to provide additional light during the daytime. These lights are normally powered by the electric grid, but some run on local generators, and emergency generators serve as backups in hospitals and other...
systems were perfected, and electricity generation was one of the hot-bulb engines main uses. The engine could achieve higher R.P.M. than a standard reciprocating steam engine (although high-speed steam engines were developed during the 1890s), and its low fuel and maintenance requirements (including the ability to be operated and maintained by only one person) made it ideal for small-scale power supply. Generator sets driven by hot-bulb engines were installed in numerous large houses (especially in rural areas) in
EuropeEurope is, by convention, one of the world's seven continents. Comprising the westernmost peninsula of Eurasia, Europe is generally divided from Asia to its east by the water divide of the Ural Mountains, the Ural River, the Caspian Sea, the Caucasus Mountains , and the Black Sea to the southeast...
, as well as in factories, theatres,
lighthouseA lighthouse is a tower, building, or framework designed to emit light from a system of lamps and lenses or, in older times, from a fire and used as an aid to navigation and to pilots at sea....
s, radio stations and many other locations where a centralised electricity grid was not available. Usually the
dynamo-In Engineering:* Dynamo, a magnetic device originally used as an electric generator* Dynamo theory, a theory relating to magnetic fields of celestial bodies* Solar dynamo, the physical process that generates the Sun's magnetic field-Europe:...
or
alternatorAn alternator is an electromechanical device that converts mechanical energy to alternating current electrical energy. Most alternators use a rotating magnetic field but linear alternators are occasionally used...
would be driven off the engine's flywheel by a flat belt, to allow the necessary 'gearing up'- making the generator turn at a faster speed than the engine. Companies such as
Armstrong WhitworthSir W G Armstrong Whitworth & Co Ltd was a major British manufacturing company of the early years of the 20th century. Headquartered in Elswick, Newcastle upon Tyne, Armstrong Whitworth engaged in the construction of armaments, ships, locomotives, automobiles, and aircraft.-History:In 1847,...
and Boulton Paul manufactured and supplied complete generating sets (both the engine and generator) from the 1900s to the late 1920s, when the formation of national grid systems throughout the world and the replacement of the hot-bulb engine by the
diesel engineA diesel engine is an internal combustion engine that uses the heat of compression to initiate ignition to burn the fuel, which is injected into the combustion chamber during the final stage of compression...
caused a drop in demand.
The engines were also used in areas where the fire of a steam engine would be an unacceptable fire risk. Akroyd-Stuart developed the world's first oil-engined locomotive (the 'Lachesis') for the
Royal ArsenalThe Royal Arsenal, Woolwich, originally known as the Woolwich Warren, carried out armaments manufacture, ammunition proofing and explosives research for the British armed forces. It was sited on the south bank of the River Thames in Woolwich in south-east London, England...
,
WoolwichWoolwich is a suburb in south-east London, England in the London Borough of Greenwich, on the south side of the River Thames, though the tiny exclave of North Woolwich is on the north side of the river. Woolwich formed part of Kent until 1889 when the County of London was created...
, where the use of locomotives had previously been impossible due to the risk. Hot-bulb engines proved very popular for industrial engines in the early 20th century, but lacked the power to be used in anything larger.
Compression ignition
Herbert Akroyd Stuart was always keen to improve the efficiency of his engine. The obvious way to do this was to raise the
compression ratioThe compression ratio of an internal-combustion engine or external combustion engine is a value that represents the ratio of the volume of its combustion chamber; from its largest capacity to its smallest capacity...
to increase the engine's thermal efficiency. However, above ratios of around 8:1 the fuel oil in the vapouriser would ignite before the piston reached the limit of its travel. This pre-detonation caused rough running, power loss and ultimately engine damage (see
engine knockingKnocking in spark-ignition internal combustion engines occurs when combustion of the air/fuel mixture in the cylinder starts off correctly in response to ignition by the spark plug, but one or more pockets of air/fuel mixture explode outside the envelope of the normal combustion front...
for more information). Working with engineers at
Hornsby'sRichard Hornsby & Sons was an engine and machinery manufacturer in Lincolnshire, England from 1828 until 1918.-Formation:The company bearing the name of Richard Hornsby , the agricultural engineer, was founded when Richard opened a blacksmithy in Grantham, Lincolnshire in 1815 with Richard Seaman,...
, Akroyd Stuart developed a system whereby the compression ratio was increased to as much as 18:1 and fuel oil was delivered to the cylinder only when the piston reached top dead centre, thus preventing pre-ignition.
This system was patented in October 1890 and development continued. In 1892 (5 years before
Rudolf Diesel'sRudolf Christian Karl Diesel was a European inventor and mechanical engineer, famous for the invention of the diesel engine.-Early life:...
first prototype), engineers at Hornsby's built an experimental engine. The vapouriser was replaced with a standard
cylinder headIn an internal combustion engine, the cylinder head sits above the cylinders and consists of a platform containing part of the combustion chamber and the location of the valves and spark plugs...
and used a high-pressure fuel nozzle system. The engine could be started from cold and ran for 6 hours, making it the world's first internal combustion engine to run on purely compression ignition. However, to build a fully practical fuel injection system required using
machiningConventional machining, one of the most important material removal methods, is a collection of material-working processes in which power-driven machine tools, such as lathes, milling machines, and drill presses are used with a sharp cutting tool to mechanically cut the material to achieve the...
techniques and building to tolerances that were not possible to
mass produceMass production is the production of large amounts of standardized products, including and especially on assembly lines...
at the time. Hornsby's was also working at full capacity building and selling hot-bulb engines, so these developments were not pursued.
Replacement
From around 1910, the
diesel engineA diesel engine is an internal combustion engine that uses the heat of compression to initiate ignition to burn the fuel, which is injected into the combustion chamber during the final stage of compression...
was improved dramatically, with more power being available at greater efficiencies than the hot-bulb engine could manage (Diesel engines can achieve nearly 50% efficiency if designed with maximum economy in mind). Diesel engines offered greater power for a given engine size due to the more efficient combustion method (they had no hot-bulb, relying purely on compression-ignition) and greater ease of use as they required no pre-heating.
The hot-bulb engine was limited in its scope in terms of speed and overall power-to-size ratio. To make a hot-bulb engine capable of powering a ship or locomotive, it would have been prohibitively large and heavy. The hot-bulb engines used in
LandiniLandini SpA, headquartered in Fabbrico, Italy, was founded by Giovanni Landini in 1884 to produce agricultural equipment. Landini had just started making tractors in 1925 when Giovanni died preventing the completion of the first prototype tractor...
tractors were as much as 20 litres in capacity for relatively low power outputs. To create even combustion throughout the multiple hot-bulbs in multi-cylinder engines is difficult. The hot-bulb engine's low compression ratio in comparison to diesel engines limited its efficiency, power output and speed. Most hot-bulb engines could run at a maximum speed of around 100 rpm, while by the 1930s diesel engines capable of 2,000 rpm were being built. Also, due to the design of hot bulb and the limitations of current technology in regards to the injector system, most hot-bulb engines were single-speed engines, running at a fixed speed, or in a very narrow speed range. Diesel engines can be designed to operate over a much wider speed range, making them more versatile. This made these medium-sized diesels a very popular choice for use in generator sets, replacing the hot-bulb engine as the engine of choice for small-scale power generation.
The development of small-capacity, high-speed diesel engines in the 1930s and 1940s, lead to hot-bulb engines falling dramatically out of favour. The last large-scale manufacturer of hot-bulb engines stopped producing them in the 1950s and they are now virtually extinct in commercial use, except in very remote areas of the developing world. An exception to this is marine use; hot-bulb engines were widely fitted to inland
bargeA barge is a flat-bottomed boat, built mainly for river and canal transport of heavy goods. Some barges are not self-propelled and need to be towed by tugboats or pushed by towboats...
s and
narrowboatA narrowboat or narrow boat is a boat of a distinctive design, made to fit the narrow canals of England and Wales.In the context of British Inland Waterways, "narrow boat" refers to the original working boats built in the 18th, 19th, and 20th centuries for carrying goods on the narrow canals...
s in Europe. The United Kingdom's first two self-powered "motor" narrowboats—Cadbury's
BournvilleBournville is a model village on the south side of Birmingham, England, best known for its connections with the Cadbury family and chocolate – including a dark chocolate bar branded "Bournville". It is also a ward within the council constituency of Selly Oak and home to a campus of the...
I and
Bournville II in 1911—were powered by 15 horsepower Bolinder single-cylinder hot-bulb engines, and this type became common between the 1920s and the 1950s. With hot-bulb engines being generally long-lived and ideally suited to such a use, it is not uncommon to find vessels still fitted with their original hot-bulb engines today.
Ignoring certain differences (electrical initial heating, differing fuels, high RPMs—at least in the small model aircraft types) the modern
Glow Plug engineFor the glow plugs used in automotive diesel engines, see GlowplugA glow plug is a device, similar to a spark plug, used to ignite the fuel in the very small internal combustion engines typically used in model aircraft, model cars and similar applications...
could be considered the latest incarnation of these "hot spot" ignition based engines.
1890s–1910
The hot-bulb engine is often confused with the diesel engine
, and it is true that the two engines are very similar. A hot-bulb engine features a prominent hot-bulb vaporiser; a Diesel engine does not. Other significant differences are:
- The hot-bulb engine mostly reuses the heat retained in the vaporiser to ignite the fuel with, achieving about 12% efficiency..
- The Diesel engine uses only compression to ignite the fuel. It operates at pressures many times higher than the hot-bulb engine, resulting in 35% efficiency.
- The hot bulb engine required preheating of the hot bulb with a torch for about 15 minutes before starting.
There is also a crucial difference in the timing of the fuel injection process:
- In the hot-bulb engine, before 1910 fuel was injected earlier into the vapouriser (during the intake stroke). This caused the start of combustion to be out of synchronization with the crank angle, meaning that the engine would only run smoothly at one low-speed or load. If the engine's load increased, so would the temperature of the bulb, causing the ignition period to advance, causing pre-ignition. To counteract pre-ignition, water would be dripped into the air intake, providing some flexibility.
- In the diesel engine, fuel is injected into the cylinder, with an adjusted timing relative to the engine speed and load, shortly before the top dead center of the Compression Stroke is reached.
There are is another, detailed difference in the method of fuel injection:
- The hot-bulb engine uses a medium-pressure pump to deliver fuel to the cylinder, through a simple nozzle.
- In the original Diesel engine, fuel was sprayed into the cylinder by high pressure compressed air, through an injector. The camshaft lifted a spring-loaded pin to initiate fuel delivery though the nozzle.
During this period technology had not advanced to the point that oil engines could run faster than 150 rpm. The structure of these engines were basically the same as steam engines and without pressured lubrication.
In hot-bulb engines, fuel is injected at low pressure, using a more economical and more reliable, and simpler configuration. However, by not using compressed air injection it is less efficient.
In this period diesel and hot bulb engines were four stroke. In 1902 F. Rundlof invented the two-stroke crankcase scavenged engine that went on to become the prevalent hot bulb type engine.
1910–1950s
Direct injected small diesel engines still were not practical. and the prechambered indirect injected engine was invented, along with the requirement of
glowplugFor the similar device used in model aircraft engines, see Glow plug .A glowplug is a heating device used to aid starting diesel engines.-Purpose:...
s to be used for starting. With developing technology Robert Bosch GmbH pump-and injector system could be build run at a much higher pressure and combining it with high precision injectors high speed diesels were produced in 1927.
The hot bulbs started to develop cracks and breakups and were gradually replaced by water cooled cylinder heads with a flat hot spot. Over time the compression ratios were increased from to .Fuel injection started from 135 degrees before top dead center , with low compression to 20 degrees before top dead center with later higher compression engines increasing the hot air factor for ignition and increasing the fuel efficiency. Glowplugs finally replaced the preheating with a blowtorch methods and engine speeds were increased, resulting in what is now classified as an indirect injection diesel .
Hot bulb or prechambered engines are always easier to produce. , more reliable and could handle smaller amounts of fuel in smaller engines, than the direct injected "pure" diesels could.
Production
Hot bulb engines were built by a large number of manufacturers, usually in modest series.These engines were slow running (300-400 RPM) and mostly with cast iron parts including pistons. The fuel pump was usually made with a brass housing and steel plunger operating with a variable stroke length. This resulted in a simple, rugged heavy engine. Therefore they could be machined in an average machine shop without special tools.
The Pythagoras Engine Factory in Norrtälje in Sweden is kept as a museum (the
Pythagoras Mechanical Workshop MuseumPythagoras Mechanical Workshop Museum is located in the premises of the earlier engine factory Pythagoras at the town of Norrtälje in the province of Uppland in Sweden. At the museum, production facilities and working conditions from the first half of the 20th century are on display...
), and has a functioning production line and extensive factory archives.
See also
- Diesel engine
A diesel engine is an internal combustion engine that uses the heat of compression to initiate ignition to burn the fuel, which is injected into the combustion chamber during the final stage of compression...
- Hesselman engine
The Hesselman engine is a hybrid between a petrol engine and a Diesel engine introduced by Swedish engineer Jonas Hesselman in 1925. It represented the first use of direct gasoline injection on a spark-ignition engine...
- History of the internal combustion engine
Although various forms of internal combustion engines were developed before the 19th century, application was hindered until the commercial drilling and production of petroleum began in the mid-1850s...
- Fairbanks Morse
- Fuel injection
Fuel injection is a system for mixing fuel with air in an internal combustion engine. It has become the primary fuel delivery system used in gasoline automotive engines, having almost completely replaced carburetors in the late 1980s....
- Gasoline direct injection
In internal combustion engines, gasoline direct injection is a latest variant of fuel injection employed in modern two- and four- stroke petrol engines...
- Indirect injection
In an internal combustion engine, the term indirect injection refers to a fuel injection where fuel is not directly injected into the combustion chamber...
- Internal combustion engine
The internal combustion engine is an engine in which the combustion of a fuel occurs with an oxidizer in a combustion chamber. In an internal combustion engine the expansion of the high temperature and pressure gases, which are produced by the combustion, directly applies force to a movable...
- Lanz Bulldog
The Lanz Bulldog was a tractor manufactured by Heinrich Lanz AG in Mannheim, Baden-Württemberg, Germany. Production started in 1921 and various versions of the Bulldog were produced up to 1960. Deere & Company purchased Lanz in 1956 and started using the name "John Deere Lanz" for the Lanz product...
- Prosper L'Orange
Prosper L'Orange was a German engineer and inventor who pioneered the precombustion chamber , which made possible high-speed Diesel engines that did not require an air compressor, and enabled them to be built small enough for use in road vehicles.-Career:L'Orange moved to Germany and studied...
Patents
- US Patent 845140 Combustion Engine, dated February 26 1907.
- US Patent 502837 Engine operated by the explosion of mixtures of gas or hydrocarbon vapor and air, dated August 8 1893.
- US Patent 439702 Petroleum Engine or Motor, dated November 4 1890.
External links