The Hesselman engine is a hybrid between a

petrol engine A petrol engine (gasoline engine in American English) is an internal combustion engine designed to run on petrol (gasoline). Petrol engines can often be adapted to also run on fuels such as liquefied petroleum gas and ethanol blends (such as ''E ...

and a

Diesel 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-call ...

. It was designed and introduced in 1925 by

Swedish Swedish or ' may refer to: Anything from or related to Sweden, a country in Northern Europe. Or, specifically: * Swedish language, a North Germanic language spoken primarily in Sweden and Finland ** Swedish alphabet, the official alphabet used by ...

engineer

Jonas Hesselman Jonas Hesselman (9 April 1877- 20 December 1957) was a Swedish engineer. He built the first spark ignition engine with direct injection of fuel into the cylinder. Biography Knut Jonas Elias Hesselman was born at Å församling in Östergöt ...

(1877-1957). It represented the first use of direct gasoline injection on a

spark-ignition engine A spark-ignition engine (SI engine) is an internal combustion engine, generally a petrol engine, where the combustion process of the air-fuel mixture is ignited by a spark from a spark plug. This is in contrast to compression-ignition engines, ty ...

used to power a road going vehicle. Hesselman engines saw use in heavy trucks and buses in models produced in the 1920s and 1930s.

Operation

The Hesselman engine incorporates a combustion process with regular intake air compression. The fuel is direct-injected into the combustion chamber at the very end of the compression stroke, near top dead centre (TDC). Due to low compression, the inhomogeneous air-fuel mixture must be ignited by a

spark plug A spark plug (sometimes, in British English, a sparking plug, and, colloquially, a plug) is a device for delivering electric current from an ignition system to the combustion chamber of a spark-ignition engine to ignite the compressed fuel/air ...

. Under full load, Hesselman engine uses quality torque controlling without throttling, whilst under medium load and when idling, a

throttle valve A throttle is the mechanism by which fluid flow is managed by constriction or obstruction. An engine's power can be increased or decreased by the restriction of inlet gases (by the use of a throttle), but usually decreased. The term ''throttle'' ...

ensures a stable engine speed. Injection duration can be manipulated to adapt to the engine load, with the injection end point remaining always the same. The valves are shaped in a way that they generate a swirl that helps mixing air and fuel. Hesselman engine is a

multifuel Multifuel, sometimes spelled multi-fuel, is any type of engine, boiler, or heater or other fuel-burning device which is designed to burn multiple types of fuels in its operation. One common application of multifuel technology is in military sett ...

engine, capable of running on

petroleum Petroleum, also known as crude oil, or simply oil, is a naturally occurring yellowish-black liquid mixture of mainly hydrocarbons, and is found in geological formations. The name ''petroleum'' covers both naturally occurring unprocessed crud ...

products such as

oil An oil is any nonpolar chemical substance that is composed primarily of hydrocarbons and is hydrophobic (does not mix with water) & lipophilic (mixes with other oils). Oils are usually flammable and surface active. Most oils are unsaturated ...

kerosene Kerosene, paraffin, or lamp oil is a combustible hydrocarbon liquid which is derived from petroleum. It is widely used as a fuel in aviation as well as households. Its name derives from el, κηρός (''keros'') meaning "wax", and was regi ...

petrol Gasoline (; ) or petrol (; ) (see ) is a transparent, petroleum-derived flammable liquid that is used primarily as a fuel in most spark-ignited internal combustion engines (also known as petrol engines). It consists mostly of organic co ...

diesel oil Diesel fuel , also called diesel oil, is any liquid fuel specifically designed for use in a diesel engine, a type of internal combustion engine in which fuel ignition takes place without a spark as a result of compression of the inlet air and t ...

. Although a mixture of features of both

Otto cycle An Otto cycle is an idealized thermodynamic cycle that describes the functioning of a typical spark ignition piston engine. It is the thermodynamic cycle most commonly found in automobile engines. The Otto cycle is a description of what happ ...

and

Diesel cycle The Diesel cycle is a combustion process of a reciprocating internal combustion engine. In it, fuel is ignited by heat generated during the compression of air in the combustion chamber, into which fuel is then injected. This is in contrast to ign ...

, the Hesselman engine is more closely related to the

Otto engine The Otto engine was a large stationary single-cylinder internal combustion four-stroke engine designed by the German Nicolaus Otto. It was a low-RPM machine, and only fired every other stroke due to the Otto cycle, also designed by Otto. Types ...

.Richard van Basshuysen (Hrsg.): Ottomotor mit Direkteinspritzung und Direkteinblasung: Ottokraftstoffe, Erdgas, Methan, Wasserstoff, 4th edition, Springer, Wiesbaden 2017. . p. 17–18

Advantages and disadvantages

Hesselman engines could use heavier oils which were considerably cheaper than gasoline and were therefore more economical to operate for the vehicle owner. Contemporary tests also pointed to a slightly lower fuel consumption in comparison to gasoline engines of similar power. A Hesselman engine compared to a diesel engine had smaller dimensions and hence lower weight. In the 1930s knowledge of

metallurgy Metallurgy is a domain of materials science and engineering that studies the physical and chemical behavior of metallic elements, their inter-metallic compounds, and their mixtures, which are known as alloys. Metallurgy encompasses both the sc ...

was less advanced, therefore diesel engines were heavy to cope with the high compression and pressure during combustion. Later, diesel engines were developed with better materials and Hesselman engines lost this advantage. Hesselman engines had several disadvantages. Due to the low compression it was difficult to reach the working temperature. The result was an incomplete combustion. The incomplete combustion led to the spark plugs quickly fouling, and this incomplete combustion also resulted in copious unburned fuel in the exhaust, otherwise known as "heavy smoke". In today's terms, this meant that the engines generated toxic exhausts on a scale that would be considered completely unacceptable.

Users

Hesselman engines were produced by all three Swedish truck manufacturers of its day,

Scania-Vabis Scania AB is a major Swedish manufacturer headquartered in Södertälje, focusing on commercial vehicles—specifically heavy lorries, trucks and buses. It also manufactures diesel engines for heavy vehicles as well as marine and general indus ...

Tidaholms Bruk Tidaholms Bruk (the Tidaholm works) was a vehicle manufacturer. Origins Founded in the Middle Ages and over the years it merged with several smaller industries into woodworking and the making of carts. In the small community of Sandhe ...

and

Volvo The Volvo Group ( sv, Volvokoncernen; legally Aktiebolaget Volvo, shortened to AB Volvo, stylized as VOLVO) is a Swedish multinational manufacturing corporation headquartered in Gothenburg. While its core activity is the production, distributio ...

, from the late 1920s. Scania-Vabis replaced Hesselman engines with proper Diesel engines from 1936, and Volvo from 1947.

Bibliography

* (Translated title: ''Vehicle history of

Scania Scania, also known by its native name of Skåne (, ), is the southernmost of the historical provinces of Sweden, provinces (''landskap'') of Sweden. Located in the south tip of the geographical region of Götaland, the province is roughly conte ...

1891-1991'') * (Translated title: ''

trucks yesterday and today'') *Lundeberg, Erik (1931)
''Hesselmanmotorn som bilmotor''
(Stockholm: Dædalus) *George James Wells, Alexander James Wallis-Tayler (1924) ''The Diesel Engine: A Practical Treatise on the Design and Construction of the Diesel Engine'' (London: C. Lockwood and son)

References

External links

Hesselman Heavy-Oil High-Compression Engine
N.A.C.A. Technical Memorandum {{Commons category, Hesselman engines Internal combustion piston engines Swedish inventions