Engine with dry sump lubrication, separated scavenging and charging air flows and variable exhaust port timing

An internal combustion engine having a piston reciprocable within a bore of a cylinder, said piston being pivotally connected to a crankshaft by a piston rod having a wrist pin at one end engaging said piston and a crank bearing at the opposite end engaging a throw of said crankshaft, said crankshaft being rotatably mounted on a main bearing within a crankcase positioned beneath said cylinder bore, an oil reservoir being mounted on said engine, said engine comprising:

• an oil sleeve positioned between said cylinder and said crankcase, said oil sleeve having a bore therethrough coaxially aligned with said cylinder bore and sized to receive said piston, said piston being reciprocable within said oil sleeve bore, an annular oil space being defined between said piston and said oil sleeve;
• a first seal positioned between said cylinder and said oil sleeve, said first seal circumferentially surrounding said piston to substantially prevent oil within said annular oil space from flowing into said cylinder;
• a second seal mounted on and circumferentially around said piston between said wrist pin and said crankshaft, said second seal having an outer circumference engaging said oil sleeve to substantially prevent oil within said annular oil space from flowing into said crankcase;
• a first conduit extending between said oil reservoir and a first port within said oil sleeve in fluid communication with said annular oil space, said first port being positioned so as to always be between said first and second seals regardless of the position of said piston within said cylinder bore and said oil sleeve bore;
• a second conduit extending along said wrist pin from a second port in fluid communication with said annular oil space to said piston rod and along said piston rod to said crank bearing;
• and
• upon motion of said piston moving said second seal away from said first seal, lubricating oil being drawn from said oil reservoir through said first conduit and into said annular oil space to lubricate said piston, upon further motion of said piston moving said second seal toward said first seal, lubricating oil within said annular oil space being forced through said second conduit to lubricate said wrist pin and said crank bearing.

A lubrication system for a device having a piston reciprocable within a cylinder, said piston being pivotally connected to a crankshaft by a piston rod having a wrist pin at one end engaging said piston and a crank bearing at the opposite end engaging a throw of said crankshaft, said crankshaft being rotatably mounted on a main bearing within a crankcase positioned beneath said cylinder, an oil reservoir being mounted on said device, said device comprising:

• an oil sleeve positioned between said cylinder and said crankcase, said oil sleeve having a bore therethrough coaxially aligned with said cylinder bore and sized to receive said piston, said piston being reciprocable within said oil sleeve bore, an annular oil space being defined between said piston and said oil sleeve;
• a first seal positioned between said cylinder and said oil sleeve, said first seal circumferentially surrounding said piston and permitting a predetermined amount of oil to flow from said annular oil space to said cylinder bore for lubricating said piston within said cylinder;
• a second seal mounted on and circumferentially around said piston between said wrist pin and said crankshaft, said second seal having an outer circumference engaging said oil sleeve to substantially prevent oil within said annular oil space from flowing into said crankcase;
• a first conduit extending between said oil reservoir and a first port within said oil sleeve in fluid communication with said annular oil space, said first port being positioned so as to always be between said first and second seals regardless of the position of said piston within said cylinder bore and said oil sleeve bore;
• a check valve mounted within said first conduit to prevent oil back flow from said annular oil space to said reservoir;
• a second conduit extending along said wrist pin from a port in fluid communication with said annular oil space to said piston rod and along said piston rod to said crank bearing and from said crank bearing to said main bearing and then to said oil reservoir;
• and
• upon motion of said piston moving said second seal away from said first seal, lubricating oil being drawn from said oil reservoir through said first conduit and into said annular oil space to lubricate said piston, upon further motion of said piston moving said second seal toward said first seal, lubricating oil within said annular oil space being forced through said second conduit back to said oil reservoir in a closed loop circulation, thereby lubricating said wrist pin, said crank bearing and said main bearing.

A two-stroke, spark-ignited internal combustion engine having a piston reciprocable within a bore of a cylinder, said piston being pivotally connected to a crankshaft rotatably mounted within a sealed crankcase positioned beneath said cylinder bore, said engine comprising:

• a cylinder head positioned at an end of said cylinder opposite said crankcase;
• an exhaust port positioned in said cylinder between said cylinder head and said crankcase;
• a scavenging port positioned in said cylinder substantially between said exhaust port and said crankcase;
• a scavenging tube extending from said crankcase to said scavenging port and providing fluid communication between said crankcase and said cylinder bore;
• a charging port positioned in said cylinder substantially between said scavenging port and said crankcase;
• a charging tube extending from said crankcase to said charging port and providing fluid communication between said crankcase and said cylinder bore;
• a fuel metering device connected to said charging tube and supplying a fuel charge thereto;
• a one-way valve positioned in said crankcase and allowing ambient air to enter;
• during engine operation said exhaust port being first uncovered upon a power stroke of said piston allowing exhaust gases to exit said cylinder bore, said scavenging port being next uncovered upon further motion of said piston, air within said crankcase being compressed by said piston and forced through said scavenging tube and entering said cylinder bore through said scavenging port thereby forcing exhaust gases out through said exhaust port, said charging port being next uncovered upon further motion of said piston, air within said crankcase being further compressed by said piston and forced through said scavenging tube and said charging tube, said air flowing through said fuel metering device and receiving a charge of fuel therefrom, said air and said fuel charge entering said cylinder bore through said charging port;
• and
• upon the compression stroke of said piston ambient air being drawn into said crankcase through said one way valve, said charging port first being covered by said piston, said scavenging port being next covered by said piston, and said exhaust port being finally covered by said piston, said air and fuel charge within said cylinder bore being compressed by said piston and ignited by said sparkplug to initiate a subsequent power stroke of said piston.

An internal combustion engine having a piston reciprocable within a bore of a cylinder, said piston having a piston ring and being pivotally connected to a crankshaft by a piston rod having a wrist pin at one end engaging said piston and a crank bearing at the opposite end engaging a throw of said crankshaft, said crankshaft being rotatably mounted on a main bearing within a crankcase positioned beneath said cylinder bore, an oil reservoir being mounted on said engine, said engine comprising:

• an oil sleeve positioned between said cylinder and said crankcase, said oil sleeve having a bore therethrough coaxially aligned with said cylinder bore and sized to receive said piston, said piston being reciprocable within said oil sleeve bore, a first annular oil space being defined between said piston and said cylinder and a second annular oil space being defined between said piston and said oil sleeve;
• a first seal positioned between said cylinder and said oil sleeve, said first seal circumferentially surrounding said piston and permitting a predetermined amount of oil to flow between said annular oil space and said cylinder bore;
• a second seal mounted on and circumferentially around said piston between said wrist pin and said crankshaft, said second seal having an outer circumference engaging said oil sleeve to substantially prevent oil within said annular oil space from flowing into said crankcase;
• a first conduit extending between said oil reservoir and a first port within said cylinder, said first port being positioned so as to always be between said first seal and said oil ring regardless of the position of said piston within said cylinder bore;
• a check valve mounted within said first conduit to prevent oil back flow from said cylinder to said reservoir;
• a second conduit extending through said piston from a second port in fluid communication with said second annular oil space to said wrist pin;
• and
• upon motion of said piston moving said piston ring away from said first seal, lubricating oil being drawn from said oil reservoir through said first conduit and into said first annular oil space between said piston and said cylinder to lubricate said piston, upon further motion of said piston moving said cylinder ring toward said first seal, lubricating oil within said first annular oil space being forced past said first seal into said second annular oil space between said piston and said sleeve, and further through said second conduit, thereby lubricating said wrist pin.

A method of operating a spark-ignited, two-stroke engine having a piston reciprocable within a bore of a cylinder, said cylinder having a spark plug, an exhaust port, a scavenging port, a charging port, and a fuel metering system operatively associated with said charging port, said method comprising the steps of:

• opening said exhaust port upon a power stroke of said piston allowing exhaust gases to exit said cylinder bore;
• opening said scavenging port upon further motion of said piston;
• forcing air through said scavenging port into said cylinder bore;
• opening said charging port upon further motion of said piston;
• forcing air through said fuel metering device;
• charging said air forced through said fuel metering device with fuel;
• forcing said air charged with fuel into said cylinder bore through said charging port;
• closing said charging port upon a compression stroke of said piston;
• closing said scavenging port upon further motion of said piston;
• and
• closing said exhaust port upon further motion of said piston, said air and fuel charge within said cylinder bore being compressed by said piston and ignited by said sparkplug to initiate a subsequent power stroke of said piston.

An internal combustion engine having a piston reciprocable within a bore of a cylinder, said piston having a piston ring and being pivotally connected to a crankshaft by a piston rod having a wrist pin at one end engaging said piston and a crank bearing at the opposite end engaging a throw of said crankshaft, said crankshaft being rotatably mounted on a main bearing within a crankcase positioned beneath said cylinder bore, an oil reservoir being mounted on said engine, said engine comprising:

• an annular oil space being defined between said piston and said cylinder;
• a first seal positioned between said cylinder and said crankcase, said first seal circumferentially surrounding said piston and substantially preventing oil from entering said crankcase from said annular oil space;
• a first conduit extending between said oil reservoir and a first port within said cylinder, said first port being positioned so as to always be between said first seal and said piston ring regardless of the position of said piston within said cylinder bore;
• a check valve mounted within said first conduit to prevent oil back flow from said annular oil space to said reservoir;
• a second conduit extending from a second port in fluid communication with said annular oil space through said piston to said wrist pin;
• and
• upon motion of said piston moving said piston ring away from said first seal, lubricating oil being drawn from said oil reservoir through said first conduit and into said annular oil space between said piston and said cylinder to lubricate said piston, upon further motion of said piston moving said cylinder ring toward said first seal, lubricating oil within said annular oil space being forced through said second conduit thereby lubricating said wrist pin.

An internal combustion engine having a piston reciprocable within a bore of a cylinder, said piston being pivotally connected to a crankshaft by a piston rod having a wrist pin at one end engaging said piston and a crank bearing at the opposite end engaging a throw of said crankshaft, said crankshaft being rotatably mounted on a main bearing within a crankcase positioned beneath said cylinder bore, an oil reservoir being associated with said engine, said engine comprising:

• an oil sleeve positioned between said cylinder and said crankcase, said oil sleeve having a bore therethrough coaxially aligned with said cylinder bore and sized to receive said piston, said piston being reciprocable within said oil sleeve bore, an annular oil space being defined between said piston and said oil sleeve;
• a first seal positioned between said cylinder and said oil sleeve, said first seal circumferentially surrounding said piston and permitting a predetermined amount of oil to flow from said annular oil space to said cylinder bore for lubricating said piston within said cylinder;
• a second seal mounted on and circumferentially around said piston between said wrist pin and said crankshaft, said second seal having an outer circumference engaging said oil sleeve to substantially prevent oil within said annular oil space from flowing into said crankcase;
• a first conduit extending between said oil reservoir and a first port within said oil sleeve in fluid communication with said annular oil space, said first port being positioned so as to always be between said first and second seals regardless of the position of said piston within said cylinder bore and said oil sleeve bore;
• and
• upon motion of said piston moving said second seal away from said first seal, lubricating oil being drawn from said oil reservoir through said first conduit and into said annular oil space to lubricate said piston, upon further motion of said piston moving said second seal toward said first seal said predetermined amount of lubricating oil within said annular oil space being forced past said first seal to said cylinder bore for lubricating said piston within said cylinder.