Two-stroke engine
AssigneeAndreas Stihl AG & Co. KG
InventorBernd Engel
Life of this patent
Estimating the term…
Abstract
A two-stroke engine (1) includes a combustion chamber (3) which is defined by a piston (5, 44) which is mounted in the cylinder (2) to reciprocate. The piston (5, 44) has a first control surface (62) which controls an outlet (9) out of the combustion chamber (3) and two second control surfaces (63) for the transfer windows (11, 13) of at least one transfer channel (10, 12). At least two transfer windows (11, 13) are arranged on opposite sides of the cylinder bore (60). At least a first recess is provided on the piston skirt (36) which extends in the peripheral area between the two second control surfaces (63) and which is separated from the transfer window (11, 13) via a section of the piston skirt (36) in every position of the piston (5, 44).
Claims16
A two-stroke engine comprising:
- a cylinder having a cylinder bore;
- a piston mounted in said cylinder so as to be movable back and forth therein;
- a combustion chamber delimited by said piston and said combustion chamber having an outlet out of said combustion chamber;
- a piston pin;
- a connecting rod connected to said piston by said piston pin;
- a crankcase;
- a crank shaft rotatably mounted in said crankcase so as to be driven by said piston via said connecting rod;
- transfer channels having respective transfer windows opening at said cylinder bore and said transfer windows being arranged on opposite sides of said cylinder bore;
- said crankcase being connected to said combustion chamber and said outlet via said transfer channels in at least one position of said piston;
- said piston having a first control surface controlling the connection of said outlet with the combustion chamber and two second control surfaces for corresponding ones of said transfer windows;
- an air filter;
- an air channel having at least one air inlet opening at said cylinder bore;
- said air channel being configured to pass combustion air drawn by suction through said air filter to said air inlet at said cylinder bore;
- said piston having a piston pocket interconnecting said air inlet and said transfer windows and said piston pocket being configured to pass said combustion air from said air channel via said transfer windows for pre-storage in said transfer channels;
- said piston having a piston skirt;
- at least one weight reduction opening provided on said piston skirt and open toward said crankcase;
- said weight reduction opening extending between one of said second control surface and said first control surface;
- and,
- said weight reduction opening being separated from all openings in said cylinder bore by said piston skirt in every position of said piston.
A two-stroke engine comprising:
- a cylinder having a cylinder bore;
- a piston mounted in said, cylinder so as to be movable back and forth therein;
- a combustion chamber delimited by said piston and said combustion chamber having an outlet out of said combustion chamber;
- a piston pin;
- a connecting rod connected to said piston by said piston pin;
- a crankcase;
- a crank shaft rotatably mounted in said crankcase so as to be driven by said piston via said connecting rod;
- transfer channels having respective transfer windows opening at said cylinder bore and said transfer windows being arranged on opposite sides of said cylinder bore;
- said crankcase being connected to said combustion chamber and said outlet via said transfer channels in at least one position of said piston;
- said piston having a first control surface for controlling the connection of said outlet with the combustion chamber and having two second control surfaces for corresponding ones of said transfer windows;
- said piston having a piston skirt;
- at least one first weight reduction pocket provided on said piston skirt and said first weight reduction pocket extending between said two second control surfaces in the peripheral area facing toward said outlet;
- said first weight reduction pocket being separated from all of said transfer windows via a section of the piston skirt and closed to said crankcase in every position of said piston;
- and,
- said first weight reduction pocket being configured so as to be connected to said outlet in at least one position of said piston.
Dependencies are inferred from the claim text.