Exhaust valve assembly for a two-stroke internal combustion engine and method for cleaning same

Patent metadata

Field	Value
Publication number	US-10113452-B2
Application number	US-201715419175-A
Country	US
Kind code	B2
Filing date	Jan 30, 2017
Priority date	Jan 31, 2016
Publication date	Oct 30, 2018
Grant date	Oct 30, 2018

Abstract

An exhaust valve assembly for a two-stroke internal combustion engine has a valve actuator, and a two-part valve having a primary and secondary valves defining first and second decompression passages respectively. The primary valve is operatively connected to the valve actuator. The primary valve is in first, second and third primary valve positions when the valve actuator is in first, second and third actuator positions respectively. The secondary valve is in a first secondary valve position when the valve actuator is in the first or the second actuator position and in a second secondary valve position when the valve actuator is in the third actuator position. The first and second valve decompression passages fluidly communicate with each other when the valve actuator is in the second actuator position, and are fluidly separate from each other when the valve actuator is the first or the third actuator position.

First claim

What is claimed is:

1. An exhaust valve assembly for a two-stroke internal combustion engine comprising:
a valve actuator movable between a first actuator position, a second actuator position and a third actuator position, the second actuator position being intermediate the first and third actuator positions; and
a two-part valve having a primary valve and a secondary valve, the primary valve being operatively connected to the valve actuator,
the primary valve defining a first valve decompression passage,
the secondary valve defining a second valve decompression passage,
the primary valve being in a first primary valve position when the valve actuator is in the first actuator position,
the primary valve being in a second primary valve position when the valve actuator is in the second actuator position,
the primary valve being in a third primary valve position when the valve actuator is in the third actuator position,
the second primary valve position being intermediate the first and the third primary valve positions,
the secondary valve being in a first secondary valve position when the valve actuator is in any one of the first and second actuator positions,
the secondary valve being in a second secondary valve position when the valve actuator is in the third actuator position,
the first valve decompression passage fluidly communicating with the second valve decompression passage when the valve actuator is in the second actuator position, and
the first valve decompression passage being fluidly separate from the second valve decompression passage when the valve actuator is in any one of the first and third actuator positions.

2. The exhaust valve assembly of claim 1 , wherein:
the valve actuator has a fourth actuator position intermediate the second and third actuator positions,
the primary valve is in a fourth primary valve position when the valve actuator is in the fourth actuator position,
the fourth primary valve position is intermediate the second and third primary valve positions,
the secondary valve being in the first secondary valve position when the valve actuator is in the fourth actuator position,
the first valve decompression passage being fluidly separate from the second valve decompression passage when the valve actuator is in the fourth actuator position.

3. The exhaust valve assembly of claim 1 , wherein:
a third valve decompression passage is defined between the primary and secondary valves, and
the third valve decompression passage fluidly communicates the first valve decompression passage with the second valve decompression passage when the valve actuator is in the second actuator position.

4. The exhaust valve assembly of claim 3 , wherein the third valve decompression passage always fluidly communicates with the second valve decompression passage.

5. The exhaust valve assembly of claim 3 , wherein the first valve decompression passage is offset from the second valve decompression passage.

6. The exhaust valve assembly of claim 3 , wherein:
the first valve decompression passage is parallel to the second valve decompression passage, and
the third valve decompression passage is perpendicular to the first and second valve decompression passages.

7. The exhaust valve assembly of claim 1 , wherein:
the primary valve has a first surface, a second surface and an edge, the first surface facing the secondary valve, the second surface being opposite the first surface,
the first valve decompression passage defines an aperture in the second surface, and
the primary valve defines a channel extending from the aperture to the edge.

8. The exhaust valve assembly of claim 1 , further comprising at least one spring biasing the secondary valve toward the first secondary valve position.

9. The exhaust valve assembly of claim 1 , further comprising at least one auxiliary valve connected to the primary valve, the at least one auxiliary valve being movable with the primary valve.

10. The exhaust valve assembly of claim 1 , wherein the two-part valve is a first two-part valve,
the exhaust valve assembly further comprising:
a second two-part valve having a primary valve and a secondary valve, the primary valve being operatively connected to the valve actuator,
the primary valve defining a first valve decompression passage,
the secondary valve defining a second valve decompression passage,
the primary valve being in a first primary valve position when the valve actuator is in the first actuator position,
the primary valve being in a second primary valve position when the valve actuator is in the second actuator position,
the primary valve being in a third primary valve position when the valve actuator is in the third actuator position,
the second primary valve position being intermediate the first and the third primary valve positions,
the secondary valve being in a first secondary valve position when the valve actuator is in any one of the first and second actuator positions,
the secondary valve being in a second secondary valve position when the valve actuator is in the third actuator position,
the first valve decompression passage fluidly communicating with the second valve decompression passage when the valve actuator is in the second actuator position, and
the first valve decompression passage being fluidly separate from the second valve decompression passage when the valve actuator is in any one of the first and third actuator positions.

11. The exhaust valve assembly of claim 1 , wherein the valve actuator is an electrical valve actuator; and
the exhaust valve assembly further comprises a push-pull cable operatively connecting the two-part valve to the valve actuator.

12. A two-stroke internal combustion engine comprising:
a crankcase;
a crankshaft disposed at least in part in the crankcase;
a cylinder block connected to the crankcase;
a cylinder defined in the cylinder block, the cylinder having a cylinder axis, the cylinder defining a decompression port and an exhaust port, the exhaust port being disposed between the decompression port and the crankshaft with respect to a direction defined by the cylinder axis,
the cylinder block defining an exhaust passage extending from the exhaust port and a cylinder decompression passage extending from the decompression port;
a piston movably disposed within the cylinder and being operatively connected to the crankshaft;
an exhaust valve selectively extending into the exhaust passage, the valve defining a valve decompression passage; and
a valve actuator operatively connected to the exhaust valve, the valve actuator being movable between a first actuator position, a second actuator position and a third actuator position, the second actuator position being intermediate the first and third actuator positions,
at least a portion of the exhaust valve being in a first valve position when the valve actuator is in the first actuator position,
at least the portion of the exhaust valve being in a second valve position when the valve actuator is in the second actuator position,
at least the portion of the exhaust valve being in a third valve position when the valve actuator is in the third actuator position,
the second valve position being intermediate the first and the third valve positions,
at least the portion of the valve extending further in the exhaust passage in the first valve position than in the second valve position,
at least the portion of the valve being withdrawn from the exhaust passage in the third valve position,
the valve decompression passage fluidly communicating the cylinder decompression passage with the exhaust passage when the valve actuator is in

Assignees

• Brp Rotax Gmbh & Co Kg

Inventors

• Matheis Andreas
• Doppelbauer Markus
• Schallauer Martin
• Berger Christian
• Roland Guenther

Classifications

• F01L3/20 Primary

  Shapes or constructions of valve members, not provided for in preceding subgroups of this group · CPC title

• F02B75/02

  Engines characterised by their cycles, e.g. six-stroke · CPC title

• F02D2013/0288

  for cleaning the valves · CPC title

• F02B33/04

  with simple crankcase pumps, i.e. with the rear face of a non-stepped working piston acting as sole pumping member in co-operation with the crankcase · CPC title

• F02B77/04

  Cleaning of, preventing corrosion or erosion in, or preventing unwanted deposits in, combustion engines · CPC title