Exhaust-tuning port and timing and combustion chamber shape
AssigneePolaris Industries Inc.
InventorsJames A Barczak, Lawrence J. Hosaluk, Dallas J. Blake, Darren J. Hedlund
Life of this patent
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Abstract
A two cycle engine having a block defining an exhaust port and a cylinder, a head, and a piston defining a combustion chamber is disclosed. The exhaust port has a resonant frequency that causes a portion of the combusted and uncombusted exhaust gasses to flow from the exhaust system and back into the combustion chamber. At a speed above the predetermined speed, a majority of the portion of the combusted and uncombusted exhaust gasses flows from the exhaust system and back into the combustion chamber without engaging the skirt of the piston.
Claims20
A two cycle engine comprising:
- an engine block defining an exhaust port and a cylinder having a central axis;
- a head coupled to the engine block;
- a piston having a skirt, the cylinder, head and piston defining a combustion chamber, wherein the piston is slidably disposed within the cylinder and configured oscillate at a plurality of frequencies which are a function of the rate fuel is being added to the combustion chamber;
- an exhaust system having a resonant frequency that causes a portion of combusted and uncombusted exhaust gasses to flow from the exhaust system and back into the exhaust port;
- wherein the exhaust port has a first portion adjacent to the cylinder angled at more than about 100 degrees from the central axis directing exhaust gas away from the head, wherein at a plurality of engine speeds below a predetermined engine speed, more than 50% of the combusted and uncombusted exhaust gasses flow from the exhaust port back onto the piston skirt and into the combustion chamber, and wherein at a speed above the predetermined speed, more than 70% of the combusted and uncombusted exhaust gasses flow from the exhaust port back into the combustion chamber without substantially engaging the skirt of the piston.
An engine comprising:
- an engine block, a cylinder wall having a central axis and, a piston having a piston skirt, and an engine head defining a combustion chamber, defined within the cylinder wall is an exhaust system having an exhaust port having a first portion adjacent to the cylinder angled at an obtuse angle from the central axis, directing exhaust gas away from the exhaust system having resonant frequency that causes a portion of combusted and uncombusted exhaust gasses to flow from the exhaust system and back through the exhaust port into the combustion chamber, wherein at a plurality of engine speeds below an engine speed of 6500 RPM, a majority of the portion of the combusted and uncombusted exhaust gasses flowing from the exhaust port back into the combustion chamber impinges on to the piston skirt, and at a speed above the 6500 RPM, more than 60% of the combusted and uncombusted exhaust gasses flow from the exhaust port and back into the combustion chamber without engaging the skirt of the piston.
An engine comprising:
- an engine block, a cylinder wall, a piston having a piston skirt, and engine head defining a combustion chamber, the engine head defining a concave horn torus surface which defines a portion of the combustion chamber;
- and
- a spark plug disposed at a central location in the horn torus surface.
Dependencies are inferred from the claim text.