WO1999002829B1 - Improvements in and relating to internal combustion engines - Google Patents

Abstract

An internal combustion engine (1) has a positive displacement supercharger (8) which can be used with particular advantage in an underpumping two stroke engine which is in the form of a valved diaphragm which reciprocates in a housing to deliver positive pulses of air. The internal combustion engine (1) also has an oiling system which comprises injecting oil between the piston (4) and cylinder walls (2) at discrete time intervals and any excess oil is removed through galleries in the piston (4), con rod (5) and main shaft (6) preferably by a vacuum exerted on the galleries. Various other innovative features include a two part exhaust valve (9), generation of the vacuum by a positive displacement supercharger, a two-part cylinder head (3), use of inserts on moving parts to increase the efficiency of an underpumping engine and a specially constructed flywheel (11).

Claims

50

AMENDED CLAIMS

[received by the International Bureau on 22 January 1999 (22.01.99); original claim 80 cancelled; original claims 1, 79 amended; original claims 81-84 have been renumbered as claim 80-83; remaining claims unchanged (4 pages)]

1. An internal combustion engine of the type including :-

a piston having a crown and side wall housed within a cylinder block in a cylinder bore;

the piston connected by a con rod to a crankshaft, said con rod having respective little and big ends, the piston reciprocating between bottom dead centre ( BDC ) and top dead centre ( TDC ) , within the cylinder bore;

bearings for various parts of the engine;

an air transfer port in the cylinder bore;

an exhaust port in the cylinder bore connected to an exhaust pipe;

an oil storage sump;

a crankcase housing the piston, con rod and portion of the crankshaft;

an air charging chamber formed by portion of the cylinder bore and the crankcase;

an air inlet duct for delivery of air to the charging chamber; and

air transfer porting between the charging chamber and the air transfer port; 51

characterised in that the air inlet duct is fed by a positive displacement supercharger mounted outside the air charging chamber and having a working stroke delivering air to the engine and a return stroke drawing air into the supercharger.

2. An internal combustion engine as claimed in claim 1, in which the supercharger comprises :-

a housing divided by a diaphragm into a front delivery chamber communicating via an outlet with the air inlet duct and a rear chamber open to the atmosphere;

means for moving the diaphragm across the chamber towards and away from the outlet; and

a one way valve associated with the diaphragm to only allow passage of air between the rear and front chambers during the return stroke of the diaphragm away from the outlet.

3. An internal combustion engine as claimed in claim 2, in which the means for moving the diaphragm comprises a piston formed from a plate secured to the diaphragm encircling the crankshaft and slidable thereon under the action of a cam, the one way valve being incorporated in the plate.

4. An internal combustion engine as claimed in any preceding claim, in which there is a timed delivery valve in the air inlet duct.

5. An internal combustion engine as claimed in claim 4, in which the timed delivery valve is open during a substantial portion of the superchargers working

79. A supercharged internal combustion engine of the type in which the supercharger is of the positive displacement type having a working stroke for delivering air to the engine combustion chamber and a return stroke drawing air through an air inlet into the supercharger, characterised in that the supercharger includes:

a housing divided by a diaphragm into a front delivery chamber communicating via an outlet with the air inlet duct and a rear chamber open to the atmosphere;

means for moving the diaphragm across the chamber towards and away from the outlet; and

a one way valve associated with the diaphragm to only allow passage of air between the rear and front chambers during the return stroke of the diaphragm away from the outlet.

80. A supercharged internal combustion engine as claimed in claim 79, in which the means for moving the diaphragm comprises a piston formed from a plate secured to the diaphragm encircling the crankshaft and slidable thereon under the action of a cam, the one way valve being incorporated in the plate.

81. A supercharged internal combustion engine as claimed in claim 79 or 80, in which the supercharger feeds the engine indirectly through an accumulator chamber having an outlet valve so as to deliver a pulsed charge of air to the combustion chamber.

82. A supercharged internal combustion engine as claimed in claim 81, in which the valve is pressure

AMENDED SHEET (ARTICLE 1§J 53

controlled.

A supercharged internal combustion engine as claimed in claim 81 or 82, in which the operation of the valve is synchronised with the engine cycle.