Exhaust valve assembly for a two-stroke internal combustion engine

Patent metadata

Field	Value
Publication number	US-11891930-B2
Application number	US-202117552856-A
Country	US
Kind code	B2
Filing date	Dec 16, 2021
Priority date	Nov 24, 2017
Publication date	Feb 6, 2024
Grant date	Feb 6, 2024

Abstract

A method of operating an exhaust valve of a two-stroke internal combustion engine is disclosed. The engine has a cylinder and a piston movably disposed within the cylinder. The cylinder defines at least one exhaust port for discharging exhaust fluid from the cylinder. The exhaust valve is configured to cyclically obstruct the exhaust port. The method includes: rotating the exhaust valve in a first direction for clearing the exhaust port before the piston uncovers the exhaust port during a downstroke of the piston, the first direction being opposite a direction of rotation of a crankshaft of the engine; and rotating the exhaust valve in the first direction for at least partially closing the exhaust port before the piston fully covers the exhaust port during an upstroke of the piston, said rotating of the exhaust valve relative to the rotation of the crankshaft at least partially counterbalancing the crankshaft.

First claim

What is claimed is:

1. A method of operating an exhaust valve of a two-stroke internal combustion engine, an exhaust valve assembly of the two-stroke engine including the exhaust valve and a weighted member, the exhaust valve and the weighted member being disposed on a same side of an axis of rotation of the exhaust valve, the engine comprising a cylinder and a piston movably disposed within the cylinder, the piston being movable along a cylinder axis of the cylinder in a reciprocating motion including an upstroke and a downstroke, the cylinder defining at least one exhaust port for discharging exhaust fluid from the cylinder, the exhaust valve being configured to cyclically obstruct the exhaust port, the method comprising:
rotating the exhaust valve in a first direction for clearing the exhaust port before the piston uncovers the exhaust port during the downstroke of the piston, the first direction being opposite a direction of rotation of a crankshaft of the engine; and
rotating the exhaust valve in the first direction for at least partially closing the exhaust port before the piston fully covers the exhaust port during the upstroke of the piston,
said rotating of the exhaust valve and corresponding rotation of the weighted member relative to the rotation of the crankshaft at least partially counterbalancing the crankshaft.

2. The method of claim 1 , wherein the exhaust valve closes the exhaust port from an upper edge of the exhaust port toward a lower edge of the exhaust port.

3. The method of claim 1 , wherein the exhaust valve is continuously rotating during operation of the engine.

4. The method of claim 1 , wherein a rotational speed of the exhaust valve is equal to a rotational speed of the crankshaft.

5. The method of claim 1 , wherein a rotational speed of the exhaust valve is half of a rotational speed of the crankshaft.

Assignees

• Brp Rotax Gmbh & Co Kg

Inventors

• Foxhall Nigel
• Doppelbauer Markus
• Kusel Heinz
• Zarhuber Matthias
• Kirchberger Roland
• Winkler Franz
• Abis Andrea

Classifications

• F01M13/0011 Primary

  Breather valves · CPC title

• F01L7/12 Primary

  specially for two-stroke engines (F01L7/04 takes precedence) · CPC title

• F01L7/16

  Sealing or packing arrangements specially therefor · CPC title

• F01M2013/0044

  with one or more valves · CPC title

• F02B2075/025

  two · CPC title