Definition

Noun: 1. A type of internal combustion engine in which the cylinders are arranged in a circle around a central crankcase. The pistons' connecting rods are attached to a single crankshaft at the center. 2. A type of internal combustion engine in which power is transmitted directly to rotating components, most notably the Wankel engine. This design uses a triangular rotor that orbits within an oval chamber to complete the combustion cycle, rather than using traditional pistons and cylinders.

Usage Examples

• The early airplanes often used a rotary engine where the entire engine block and cylinders spun around a fixed crankshaft.
• The Mazda RX-7 is famous for its use of a Wankel rotary engine, which is compact and produces high power for its size.
• Compared to a piston engine, a rotary engine has fewer moving parts and runs very smoothly.

Advanced Usage

• Engineering Context: In technical discussions, "rotary engine" can be ambiguous. It is crucial to specify whether one is referring to the radial rotary engine (common in early aviation, where the crankcase and cylinders rotate) or the Wankel rotary engine (where an eccentric rotor provides the motion). The modern usage often defaults to the Wankel design.
• "rotary" vs. "radial": In modern terminology, a stationary-crankcase radial engine is often distinguished from a true rotating-crankcase rotary engine. Both have cylinders arranged radially.

Variants and Related Words

• Wankel engine (n): The most common and successful type of rotary engine using a triangular rotor. This is often synonymous with "rotary engine" in automotive contexts.
  • The Wankel engine was invented by Felix Wankel.
• Radial engine (n): An engine with cylinders arranged like spokes on a wheel. A subtype is the rotating rotary engine.
  • The radial engine on the vintage biplane was meticulously restored.
• Piston engine (n): The conventional engine type that a rotary engine is often contrasted with.
  • A rotary engine lacks the reciprocating motion of a piston engine.

Synonyms

• Wankel engine (for the second, modern definition).
• Radial engine (can be a synonym for the first definition, but with a technical distinction).

Related Phrases & Compounds

• Rotary actuator: A device that produces rotary motion, but not an internal combustion engine.
• Engine rotor: The central rotating component in a Wankel rotary engine.

Noun

1. an internal-combustion engine having cylinders arranged radially around a central crankcase
2. an internal-combustion engine in which power is transmitted directly to rotating components