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US 10,648,399 B2Granted
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
Estimating the term…
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 having an exhaust passage extending along an exhaust axis 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 to oscillate at a plurality of frequencies which are a function of a rate that 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 surface adjacent to the cylinder that forms an angle of between 45 degrees and 60 degrees from the central axis directing exhaust gas away from the head and the exhaust port includes a second surface extending at an angle relative to the first surface, 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.
2 more elements
An engine comprising:
- an engine block, a cylinder 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 port having an exhaust passage defined by a first exhaust port portion adjacent to the cylinder angled at between 45 degrees and 60 degrees relative to the central axis, and an exhaust system having a resonant frequency that causes a portion of combusted and uncombusted exhaust gasses to flow from the exhaust system back through the exhaust port and 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 an engine head defining a combustion chamber, the engine head defining a concave horn torus surface which defines a portion of the combustion chamber;
- a spark plug disposed at a central location in the horn torus surface;
- and an exhaust system having an exhaust port and 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 surface adjacent to the cylinder wall that forms an angle of between 45 degrees and 60 degrees from a central axis directing exhaust gas away from the engine head and the exhaust port includes a second surface extending at an angle relative to the first surface, 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.
1 more element
A two cycle engine comprising:
- an engine block defining an exhaust port having an exhaust passage extending along an exhaust axis 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 at least a portion of the exhaust axis adjacent to the cylinder define at least in part by a first surface of the exhaust port angled at between about 45 degrees and 60 degrees from the central axis directing exhaust gas away from the head;
- wherein at least one of (i) the head has a surface representing a cutaway of a torus that has a combustion dome diameter that at mid height is between 50 and 60% of bore diameter or (ii) the head defines a portion of the combustion chamber and the engine further has a sparkplug which linearly positions a spark initiating member between 35% and 45% from a crown of the head height from the piston surface at top dead center.
3 more elements
Dependencies are inferred from the claim text.