The correct spelling of the word "Hot bulb" is /hɒt bʌlb/. The word "hot" is spelled with an "o" and a "t," while "bulb" is spelled with a "b," a "u," and an "l." The IPA phonetic transcription shows that the "o" in "hot" is pronounced with an /ɒ/ sound, which is slightly different from the American English pronunciation of /ɑ/. Similarly, the "u" in "bulb" is pronounced with an /ʌ/ sound, which is similar to the American English pronunciation of /ʌ/.
A "hot bulb" refers to a specific type of internal combustion engine used primarily in agricultural machinery and vintage vehicles. The term "hot bulb" refers to the design feature of a hollow bulb or chamber located within the engine's cylinder head. This bulb is filled with a heated metal wire or coil, which is kept at a high temperature even when the engine is not running.
When the engine is started, a volatile fuel mixture is introduced into the cylinder. The high temperature of the bulb causes the fuel mixture to vaporize and ignite, thereby creating the necessary combustion for the engine to function. This design eliminates the need for spark plugs or other ignition systems commonly found in conventional engines.
Hot bulb engines are characterized by their simplicity and reliability. They are often used in applications where a steady output of torque is required, such as in agricultural vehicles like tractors or stationary machinery. The lack of a spark plug also allows these engines to run on a wide variety of fuel types, including low-quality or waste fuels that would not be suitable for a conventional gasoline engine.
While hot bulb engines were popular in the early 20th century, they have since been largely replaced by more efficient and modern engine designs. However, they still hold a place in the world of vintage machinery and are sometimes valued for their historical significance and nostalgic appeal.
The term "hot bulb" originates from the early days of internal combustion engines. In the late 19th and early 20th century, before the widespread use of electric ignition systems, engines relied on a hot bulb ignition system to start and run.
The hot bulb engine, also known as the heavy oil engine, was developed by Swedish engineer Jonas Hesselman in 1892. Instead of spark plugs or electric ignition, these engines featured a pre-combustion chamber called a hot bulb. The bulb was made from cast iron and heated to a high temperature using an external heat source, such as a blowtorch or a flame.
When starting the engine, fuel was injected into the hot bulb, which immediately ignited due to the high temperature. The combustion inside the bulb then transferred to the main combustion chamber, powering the engine.