# How the Wankel Rotary Engine Works

> A 1957 invention by Felix Wankel that replaces heavy, moving pistons with a triangular rotor spinning inside a chamber to create power.

- **Patent:** US 2988008
- **Original title:** Rotary piston machines
- **Owner:** WANKEL AND NSU MOTORENWERKE AG
- **Granted:** 1961
- **Status:** Public domain (expired)
- **Times cited:** 45
- **Field:** automotive, mechanical

## What it does

The Wankel engine uses a triangular rotor that spins inside an oval-shaped housing. As the rotor turns, it creates three separate combustion chambers that expand and contract. This design allows the engine to perform the four stages of combustion—intake, compression, power, and exhaust—in a continuous, circular motion rather than the up-and-down movement of traditional engines.

## What it does NOT cover

- Does not cover traditional reciprocating piston engines found in most cars.
- Does not cover electric motors or battery-powered propulsion systems.
- Does not cover gas turbine engines or jet propulsion technology.

## The clever bit

By using a trochoidal (curved) housing, the engine turns linear combustion pressure directly into rotational motion, eliminating the need for a complex crankshaft and connecting rods.

## Real-world examples

1. Mazda RX-7
2. Mazda RX-8
3. NSU Ro 80
4. Citroen GS Birotor
5. Modern range-extender generators for electric vehicles

## Why it matters

This engine promised a high power-to-weight ratio and extreme smoothness because it lacked the vibration caused by heavy pistons changing direction. It became a symbol of automotive engineering ambition, most notably powering iconic sports cars like the Mazda RX-7 and RX-8.

## Frequently asked questions

### What does How the Wankel Rotary Engine Works cover?

A 1957 invention by Felix Wankel that replaces heavy, moving pistons with a triangular rotor spinning inside a chamber to create power.

### Who owns patent US 2988008?

WANKEL AND NSU MOTORENWERKE AG owns this patent, granted in 1961.

### When does this patent expire?

This patent has expired and is now in the public domain — anyone can use the invention freely.

### What is patent US 2988008 cited by?

This patent has been cited by 45 later patents that build on its ideas.

### What problem does this patent solve?

This engine promised a high power-to-weight ratio and extreme smoothness because it lacked the vibration caused by heavy pistons changing direction. It became a symbol of automotive engineering ambition, most notably powering iconic sports cars like the Mazda RX-7 and RX-8.

### What does this patent NOT cover?

Does not cover traditional reciprocating piston engines found in most cars.

**Full plain-English explainer:** https://patentbrief.org/patent/us/2988008/wankel-rotary-engine

**Original patent:** https://patents.google.com/patent/US2988008

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_Source: PatentBrief — https://patentbrief.org. Patent facts are from public records; the plain-English explanation is PatentBrief's._


## Related patents

Semantically similar inventions in the PatentBrief corpus:

- [How Rudolf Diesel's Engine Works](https://patentbrief.org/patent/us/608845/diesel-engine) — Rudolf Diesel's 1898 patent describes a highly efficient engine that ignites fuel using the heat generated by compressing air rather than using a spark plug.
- [How the String Trimmer (Weed Eater) Actually Cuts Grass](https://patentbrief.org/patent/us/3826068/weed-eater-string-trimmer) — This 1974 patent describes the mechanics of using a high-speed spinning plastic line to cut grass, replacing dangerous metal blades with flexible, non-metallic material.
- [How the Gatling Gun's Rotating Barrel Mechanism Works](https://patentbrief.org/patent/us/36836/gatling-gun) — Richard Gatling's 1862 patent for a multi-barrel firearm that used a hand-cranked rotating mechanism to fire bullets in rapid succession.
- [Leamon Souder's 1903 Design for a Spiral Escalator](https://patentbrief.org/patent/us/723325/escalator-moving-stairway) — A 1903 patent for a mechanical staircase that moves in a circular, spiraling path to transport people between floors.
- [How the First Heart-Lung Machine Oxygenated Blood](https://patentbrief.org/patent/us/2702035/heart-lung-machine-gibbon) — A 1955 invention that allowed surgeons to oxygenate a patient's blood outside the body, enabling the first successful open-heart surgeries.