US 10,240,558 B2Granted

Piston for a two-stroke engine working with advanced scavenging and a two-stroke engine

AssigneeAndreas Stihl AG & Co. KG

InventorsBirger Loew, Jonas Lank

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Abstract

A piston for a two-stroke engine operating with advanced scavenging has a piston base and a piston skirt. The piston has a piston pocket which has a smallest distance (e) from a top side of the piston base. The piston has a section plane perpendicularly to the longitudinal center axis of the piston, the distance of which section plane from the top side of the piston base is greater than the smallest distance (e). A middle plane of the piston intersects the piston skirt at a location. In the circumferential direction between the pocket and this location, a thickened area is arranged in the section plane, the greatest wall thickness of which area is at least 1.1 times the wall thickness at the location. The piston has an edge at a recess at which the piston skirt has a reduced height. A chamfer is arranged on the radially outer side of the piston.

Claims21

Dependent claims

A piston for a two-stroke engine operating with advanced scavenging, the piston comprising:

a piston base having a top side;
a piston skirt defining a first center axis;
said first center axis forming a longitudinal center axis of the piston;
the piston having two piston pin eyelets defining a second center axis;
said second center axis defining a transverse axis;
the piston defining a middle plane containing said longitudinal center axis of the piston;
said middle plane being perpendicular to said transverse axis;
the piston having at least one piston pocket arranged completely on a first side of said middle plane;
said piston pocket and said top side of said piston base mutually defining a smallest distance (e) therebetween;
the piston having a section plane perpendicular to said longitudinal center axis;
said section plane and said top side of said piston base mutually defining a distance (m) therebetween;
said distance (m) being greater than said smallest distance (e);
said piston skirt having a location at which said middle plane intersects said piston skirt in said section plane;
said piston skirt having a wall thickness (b) at said location;
the piston defining a circumferential direction;
a thickened region arranged in said section plane between said pocket and said location in said circumferential direction;
said thickened region having a wall thickness (a);
and,
said wall thickness (a) being at least 1.1 times said wall thickness (b) at said location.

16 more elements

A two-stroke engine comprising:

a cylinder having a cylinder bore;
a combustion chamber formed in said cylinder bore;
a piston having a piston base and a piston skirt;
said combustion chamber being delimited by said piston;
a crankcase defining a crankcase interior;
a crankshaft rotatably mounted in said crankcase;
said piston being configured to drive said crankshaft;
a transfer channel having a transfer window and being configured to connect said crankcase interior to said combustion chamber in at least one position of said piston;
an air channel configured to supply scavenging air;
said air channel opening at said cylinder bore via an air inlet;
said piston including a piston base having a top side and a piston skirt defining a first center axis;
said first center axis forming a longitudinal center axis of said piston;
said piston having two piston pin eyelets defining a second center axis;
said second center axis defining a transverse axis;
said piston defining a middle plane containing said longitudinal center axis of said piston;
said middle plane being perpendicular to said transverse axis;
said piston having at least one piston pocket arranged entirely on a first side of said middle plane;
said at least one piston pocket being configured to be at least partially overlapping with said air inlet and said transfer window in at least one position of said piston;
said piston pocket and said top side of said piston base mutually defining a smallest distance (e) therebetween;
said piston having a section plane perpendicular to said longitudinal center axis;
said section plane and said top side of said piston base mutually defining a distance (m) therebetween;
said distance (m) being greater than said smallest distance (e);
said piston skirt having a location at which said middle plane intersects said piston skirt in said section plane;
said piston skirt having a wall thickness (b) at said location;
said piston defining a circumferential direction;
a thickened region arranged in said section plane between said pocket and said location in said circumferential direction;
said thickened region having a wall thickness (a);
and,
said wall thickness (a) being at least 1.1 times said wall thickness (b) at said location.

26 more elements

Dependencies are inferred from the claim text.