Abstract

A piston cooling system for a pivoted piston (1) for an internal combustion engine, said piston (1) having a piston body (2), a pivot shaft (3) by which the piston body (2) may be pivoted about a pivot axis (4) within a combustion chamber of the internal combustion engine, a first arcuate sealing surface spaced from the pivot axis and transcribing a circumferential path about the pivot axis, and a second arcuate sealing surface radially offset from the first arcuate sealing surface and connected to the first arcuate sealing surface by a floor (5) of the piston body (2), a portion of said floor (5) including a combustion chamber piston crown (6), characterised in that the cooling system includes a coolant path (10) formed in the piston, said coolant path having an entry point at a first end (11) of the pivot shaft (3) and an exit point at a second end (12) of the pivot shaft (3), wherein said coolant path (10) extends from the entry point, through a first portion (13) of the pivot shaft (3), into said piston body (2), beneath the piston floor (5), on through one or more passageways (16) adjacent the piston crown (6), back to a second portion of the pivot shaft (3), and out through the exit point, each said passageway (15/16/17) having a substantially constant cross section along its length.

IPC Classes  ?

• F01C 9/00 - Oscillating-piston machines or engines
• F01P 3/10 - Cooling by flow of coolant through pistons
• F02B 53/00 - Internal-combustion aspects of rotary-piston or oscillating-piston engines

Abstract

A two stroke internal combustion engine (1) incorporating an asymmetric exhaust port/transfer port inversion device (2) characterised in that the device includes a hollow flap valve (100) adapted to pivot about a hollow pivot shaft (101) between a closed position and an open position wherein pivoting the device (2) to the open position as the piston (3) begins the compression stroke allows the transfer of air to continue after the leading edge of the piston has closed off the exhaust port (105) thereby advancing the timing of the exhaust port closing and extending the duration of air transfer from the crankcase primary compression chamber (103).

IPC Classes  ?

• F02D 13/02 - Controlling the engine output power by varying inlet or exhaust valve operating characteristics, e.g. timing during engine operation
• F01L 7/12 - Rotary or oscillatory slide-valve gear or valve arrangements specially for two-stroke engines
• F02B 33/44 - Passages conducting the charge from the pump to the engine inlet, e.g. reservoirs
• F02B 53/06 - Valve control therefor