Single-cylinder engine

Characteristics

Compared with multi-cylinder engines, single-cylinder engines are usually simpler and compact. Due to the greater potential for airflow around all sides of the cylinder, air cooling is often more effective for single cylinder engines than multi-cylinder engines. This reduces the weight and complexity of air-cooled single-cylinder engines, compared with liquid-cooled engines.

Drawbacks of single-cylinder engines include a more pulsating power delivery through each cycle and higher levels of vibration. The uneven power delivery means that often a single-cylinder engine requires a heavier flywheel than a comparable multi-cylinder engine, resulting in relatively slower changes in engine speed. To reduce the vibration level, they often make greater use of balance shafts than multi-cylinder engines, as well as more extreme methods such as a dummy connecting rod (for example the Ducati Supermono). These balancing devices can reduce the benefits of single-cylinder engines regarding lower weight and complexity.

Most single-cylinder engines used in motor vehicles are fueled by petrol (and use a four-stroke cycle), however diesel single-cylinder engines are also used in stationary applications (such as the Lombardini 3LD and 15LD).

A variation known as the split-single makes use of two pistons which share a single combustion chamber.

Uses

Early motorcycles, automobiles and other applications such as marine engines all tended to be single-cylinder. The configuration is almost exclusively used in portable tools, along with garden machinery such as lawnmowers. Single-cylinder engines also remain in widespread use in motorcycles, motor scooters, go-karts, auto rickshaws, and radio-controlled models. From 1921 to 1960, the Lanz Bulldog tractor used a large horizontally mounted single-cylinder two-stroke engine. However, they are rarely used in modern automobiles and tractors, due to developments in engine technology.

Single-cylinder engines remain the most common engine layout in motor scooters and low-powered motorcycles. The Honda Super Cub (the motor vehicle with the highest overall sales since its introduction in 1958) uses a 49 cc four-stroke single-cylinder engine. There are also several single-cylinder sportbikes (such as the KTM 690 Duke R), dual-sport motorcycles (such as the BMW G650GS) and the classic-styled Royal Enfield 500 Bullet.

The Moto3 class in the MotoGP World Championship have used four-stroke 250 cc single-cylinder engines since the class replaced 125 cc two-strokes in 2012.

Other single-cylinder engines

Engines of other sorts, like the beam engine and certain types of Stirling engine, operate using one cylinder and thus can also be considered single-cylinder engines.

References

References

1. "Single Cylinder Engines".
2. "How to Balancing a Single Cylinder Engine Crankshaft and Piston/Connecting Rod Assembly and Flywheel to Reduce Dangerous Vibration".
3. "Engine Science: The Balancing Act of Single Cylinder Engines".
4. Methods of Balancing Single Cylinder Engines. Joseph R. Harkness. SAE Transactions. Vol. 77, Section 3: Papers 680436–680591 (1968), pp. 2329-2338
5. [https://www.cycleworld.com/suzukis-supermono-engine-design Suzuki's Supermono Engine Design]. A second con-rod without a piston. Ben Purvis. April 26, 2019
6. (5 March 2009). "5 of the funkiest single-cylinder street bikes".
7. "The Single Life: 6 of the best thumpers".
8. (9 August 2016). "The 16 Best Retro Motorcycles Make Bikes Great, Again".
9. (5 April 2000). "How Car Engines Work".
10. (December 1988). "The Lanz Bulldog".
11. "690 Duke: The essence of motorcycling".
12. David Blasco. "Royal Enfield Motorcycles". Royalenfields.com.