INTERNAL COMBUSTION ENGINE GAS TRANSFER SYSTEM

Abstract: A gas transfer system providing uniflow charging and scavenging in an internal combustion, reciprocating piston engine utilizing crankcase induction and compression where piston controlled intake ports (N) are provided in the cylinder head (L) and exhaust ports (F) are provided in the cylinder (O) wherein the piston interior forms the passage from the crankcase (J) to the cylinder (O), through the piston crown, the crown being extended (D) and provided with transfer ports (A) to co-act with the cylinder intake ports (N) so that cylinder charging and scavenging occurs near the end of the power stroke as exhaust ports (F) are uncovered by the piston (C).

Description: ΩTTERI-TAJj COMBUSTION Ξ-TGBJE G-A8 TR S-FER SΪSTEM This invention relates to improvements to 2 stroke cycle engines having piston operated ports. The object of the invention is to improve efficiency of the design by changing the direction of the ga flow in regard to the charging and. scavenging of the cylinde while maintaining the simplicity of the original design. In conventional engines of this type, the fresh. charge enters the cylinder at the bottom in close proximity the exhaust ports. To scavenge the exhaust gases, the fresh 0 charge must travel up the cylinder to the combustion chamber and back down to the exhaust ports. Because of the ver shor time in the cycle for this to occur, the system cannot efficiently achieve this purpose, there being a loss of fuel through the exhaust ports and excessive mixing of the exhaus gases with the fresh charge. As with conventional engines, the invention utilises crankcase compression, the crankcase being provided with an inlet only port, as well as having the exhaust, ports located at a βimiliar position in the cylinder. The intake 0 ports, however, are located in the cylinder head. This allow for uniflow charging and scavenging of the cylinder from top to bottom. To achieve transfer of crankcase gases to the to of the cylinder through the intake ports, a portion of the piston crown is extended in the shape of a smaller piston to pass through the cylinder head at bottom dead centre of the piston stroke, being contained in the cylinder head by a suitable cylinder open at the top to the atmosphere and connected in the base to the intake ports. Because the pijβtoe and the crown extension are hollow and open to the crankcase, the piston unit forms a transfer passage from the crankcase to the top of the cylinder. Transfer ports are fitted near the top of the crown extension to align with the cylinder head intake ports, allowing crankcase gases to flow into the cylinder, the exhaust ports being uncovered by the piston at this time, so that, as with conventional engines, the intake and exhaust functions occur near the end of the power stroke. The addition of the crown extension increases the intake of crankcase gases and this is an improvement on conventional engines having the same bore and stroke, where the volume of the intake gases is less. By locating the intake ports in the cylinder head, the full circumference of the cylinder is available for placement of exhaust ports. The height of the port opening can be significantly reduced without limiting*exhaust gas flow, to improve the volumetric efficiency of the cylinder. An embodiment of the invention is described hereunder in reference to accompanying drawings in which Pig (1) and Fig (2) are partly sectioned side elevations depicting the invention in separate stages of operation wherein Fig (1) is the top of the crankcase-intake and cylinder compression stroke where transfer ports (A) and exhaust ports (F) are closed. Piston rings (E) are provided at the piston crown extension (D), and the piston proper (C). Other items include the cylinder (0), the spark plug or fuel injjector (K), the combustion chamber (B), the cylinder head (L), the connecting rod (H), the crankshaft (l), the crankcase (J), the valve providing one-way gas flow into the crankcase (G), the cylinder containing the piston crown extension in the cylinder head, (M), the intα-Eβ ox-ϋs \a j which are also transfer ports but classified separately for clarity, and Pig <2) wherein the piston (C) is at the bottom of the power stroke with transfer ports (A) and int*-. ake ports (N) are aligned, allowing a gas flow from the crankcase (J) to the combustion chamber ( ), forcing out the exhaust gases through ports (F). Inlet valve (Or) is closed.

Claims: /04112 P /A xαe claims defining the invention are as folxows ; Claim 1 . A gas transfer system in a liquid or aircooled, internal combustion, reciprocating piston engine,., of either spark or compression ignition, having a cylinder and piston, a cylinder head and combustion chamber, a piston connecting rod and crankshaft, a crankcase having an inlet port with an inlet-only valve, said cylinder having exhaust ports,, wherein said engine, piston operated intake ports are prov¬ ided in the cylinder head, said piston forming the transfer passage for crankcase gases, to the cylinder, through the intake ports, said piston having a crown extension fitted with transfer ports to co-act with said intake ports, effecting a transfer of crankcase gases as the piston nearβ the end of the power stroke, wherein causing uniflow scavenging of the cylinder from top to bottom, as the piste, on uncovers the exhaust ports, thereby providing a fresh- charge in the cylinder in preparation for the next approp¬ riate ignition process. Claim (2) A gas transfer system according to claim 1 wherein the cylinder head is provided with a cylinder to form a guide and a sealing medium for the said transfer ports in the said piston crown extension, said cylinder head cylinder being open at the top, to the atmosphere and connected in the base, by the intake ports, to the combustion chamber, said cylinder head forming the combustion chamber with the crown of the said piston as it approaches top dead centre of piston travel, said cylinder head being provided in the combustion chamber with spark and/or fuel injection facili-- -ties . Claim 3 A gas transfer system according to preceeding claims wherein the piston is an essentially hollow cylinder open to the crankcase and having a crown, said crown having an essentially hollow, centrally located, crowned cylindrical extension, rising vertically and fitted with transfer ports, so that the transfer ports and the intake ports align near the end of the power stroke, said piston and piston crown extension transfer ports having sealing means to provide an essentially leakproof contact with their respective cylinders, said piston on the ascending stroke, drawing gas * es into the crankcase through the said inlet port, said piston on the descending stroke, compressing said gases until the. intake and transfer ports align, wherein compress¬ ed crankcase gases flow up the interior of the piston unit to enter the cylinder at the combustion chamber- Claim 4- In an engine, a gas transfer system, substantially according to the embodiment described in the specification with reference to and as illustrated in the accompanying drawings. Dated this 20 th day of June 1985 ADRIAI. JACOB WONE.

Inventors: WONE ADRIAN J, WONE, ADRIAN, J.
Applicants: WONE ADRIAN J, WONE, ADRIAN, J.
Application year: 1985
Main classification: F02B25
IPC codes: F02B25, F02B33, F02B75