# US 4,398,509 A · Two-stroke motor > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 4,398,509 A - Document ID: US4398509A - Status: Granted - Kind: A - Application number: 06/211,973 - Filed: 1980-12-01 - Granted: 1983-08-16 - Earliest claimed: 1979-12-03 - Assignees: Sercati - Inventors: Eric Offenstadt; Bernard Houze - Web page: https://patentgrep.com/patent/US4398509A ## CPC - F02B 33/04: with simple crankcase pumps, i.e. with the rear face of a non-stepped working piston acting as sole pumping member in co-operation with the crankcase - F01M 3/00: Lubrication specially adapted for engines with crankcase compression of fuel-air mixture or for other engines in which lubricant is contained in fuel, combustion air, or fuel-air mixture (separating lubricant from air or fuel-air mixture before entry into cylinder F01M11/08) - F02B 25/20: Means for reducing the mixing of charge and combustion residues or for preventing escape of fresh charge through outlet ports not provided for in, or of interest apart from, subgroups F02B25/02 - F02B25/18 - F02B 33/40: of non-positive-displacement type - F02B 33/446: {having valves for admission of atmospheric air to engine, e.g. at starting} - F02B 61/02: for driving cycles - F02B 2075/025: {two} - F02B: INTERNAL-COMBUSTION PISTON ENGINES; COMBUSTION ENGINES IN GENERAL (gas-turbine plants F02C; hot-gas or combustion-product positive-displacement engine plants F02G) - F01M: LUBRICATING OF MACHINES OR ENGINES IN GENERAL; LUBRICATING INTERNAL COMBUSTION ENGINES; CRANKCASE VENTILATING ## Abstract This motor is of the type comprising a case having a cylindrical upper part in which a piston is slidably mounted and a lower part in which a crankshaft connected to the piston is disposed. The case further comprises on one hand, an intake port and an exhaust port which open onto the upper part of the case, the input port being disposed below the exhaust port, and, on the other hand, at least one transfer conduit interconnecting the two parts of the case. The motor comprises a supply circuit for non-carburetted fresh gases which is connected to at least one port of the upper part of the case, the upper edge of this at least one port being disposed below the upper edge of the exhaust port. The motor is applicable in particular to motorcycles. ## Claims ### Claim 1 A two-stroke motor comprising a case defining a generally cylindrical upper cavity and a lower cavity, a piston slidably mounted in said upper cavity, a crankshaft disposed in said lower cavity, means connecting said crankshaft to said piston, carburetted gas supply means for supplying carburetted gas, non-carburetted gas supply means for supplying non-carburetted gas, at least one of said gas supply means including said lower cavity, and transfer conduit means for transferring gas from said lower cavity to said upper cavity, said lower cavity providing crankcase compressor means for compressing the gas supplied, said upper cavity presenting an exhaust port by which burnt gas is exhausted, said exhaust port having an upper edge, a first set of intake ports spaced apart angularly around said upper cavity and through which said non-carburetted gas supply means communicates with said upper cavity and a second set of intake ports spaced apart angularly around said upper cavity and through which said carburetted gas supply means communicates with said upper cavity, the intake ports of said first set presenting upper edges disposed below said upper edge of said exhaust port, and one of said sets of intake ports being disposed above the other set, said gas supply means being arranged to commence supplying non-carburetted gas to scavenge said upper cavity after said exhaust port is uncovered by said piston and before supplying carburetted gas to said upper cavity. ### Claim 2 (depends on 1) A motor as claimed in claim 1 wherein the number of intake ports in said first set is substantially equal to the number of intake ports in said second set. ### Claim 3 (depends on 1) A motor as claimed in claim 1 wherein said transfer conduit means connects the lower one of said first and second sets of intake ports to said lower cavity. ### Claim 4 (depends on 3) A motor as claimed in claim 3 wherein said non-carburetted gas supply means includes said crankcase compressor means, said carburetted gas supply means being connected to the upper set of intake ports and including valve means for enabling the supply of carburetted gas to said upper cavity at a controlled time after said intake ports are uncovered by said piston. ### Claim 5 (depends on 4) A motor as claimed in claim 4 wherein said carburetted gas supply means includes control means responsive to the speed of the motor for continuously controlling the opening time of said valve means, whereby to advance and retard the opening time at relatively high and low engine speeds respectively. ### Claim 6 (depends on 3) A motor as claimed in claim 3 wherein said carburetted gas supply means includes said crankcase compressor means, said non-carburetted gas supply means being connected to the upper set of intake ports. ### Claim 7 (depends on 3) A motor as claimed in claim 3 wherein that one of said gas supply means which is connected to the upper set of intake ports includes further compressor means. ### Claim 8 (depends on 7) A motor as claimed in claim 7 wherein said carburetted gas supply means includes said crankcase compressor means and said non-carburetted gas supply means includes said further compressor means, the motor including gas control means for controlling the supply of carburetted gas and for controlling the intake of non-carburetted gas to said further compressor means. ### Claim 9 (depends on 7) A motor as claimed in claim 7 wherein said non-carburetted gas supply means includes said crankcase compressor means and said carburetted gas supply means includes said further compressor means and carburettor means connected to supply carburetted gas thereto. ### Claim 10 (depends on 1) A motor as claimed in claim 1 wherein said crankcase compressor means included in one of said gas supply means is also coupled to the other of said gas supply means which includes further transfer conduit means coupled with said crankcase compressor means for supplying compressed gas to said upper cavity and membrane means separating said further conduit means from said lower cavity. ### Claim 11 (depends on 1) A motor as claimed in claim 1 wherein said non-carburetted gas supply means includes a source of vaporized lubricating oil.