GB2425808A

GB2425808A - Supercharged two-stroke engine with separate direct injection of air and fuel

Info

Publication number: GB2425808A
Application number: GB0509273A
Authority: GB
Inventors: Sergio Gutierrez
Original assignee: Individual
Current assignee: Individual
Priority date: 2005-05-06
Filing date: 2005-05-06
Publication date: 2006-11-08
Also published as: GB0509273D0

Abstract

In this Supercharged Two-stroke Valveless Twin Injectors engine having two specially designed injectors for air and fuel electronically controlled for opening and closing, air scavenging is efficiently done by injecting air at high pressure through an injector 6 fed from a constant high pressure air compressor. Air injection starts when piston 3 begins to open the exhaust ports 8 at the end of the power stroke, and continues until after the piston closes the exhaust ports in its way up, at which point the fuel injector 7, fed from a constant high pressure fuel compressor injects fuel into the combustion chamber mixing it with the clean air provided by the air injector. When the required mixture is reached both injectors close. This mixture is compressed further by the raising piston until it reaches TDC, being then ignited by the spark plug 9 to start the power stroke.

Description

DESCRIPTION

Background and Summary of the Invention

Superchar2ed Two-stroke en2ine This invention relates to a supercharged two-stroke internal combustion engine.

Background

Four stroke internal combustion engines have become more powerful and more efficient than those of the past. Unfortunately, all the improvements made for better engines have increased their complexity, to the point where a modern engine has a great number of moving parts, which not only use up a high proportion of the energy generated by the engine (to move them and to carry their weight), but they make it more prone to breakdowns. The part that has evolved substantially is the valve system, for example with 16 valves for a 4 cylinder or 24 valves for a 6 cylinders, some with twin camshafts, plus all the ancillary components, one of which, the camshaft belt, has become the "Achilles heel" of modern engines. Additionally, they have become so cumbersome and complex that the cost of manufacture, maintenance and repairs are increasingly high.

Four stroke internal combustion engines are not very efficient. Only one in four of the strokes is a "power" stroke, this is 25% of the full cycle (2x360 degrees rotation of the crankshaft); the other three strokes, 75% of the full cycle, are "parasitic" strokes, needing the energy stored in the flywheel as inertial force to continue the rotation of the crankshaft until the next cylinder fires up.

In a four cylinder four stroke engine, there are two power strokes per half cycle (360 degrees rotation of the crankshaft), this is one power stroke every 180 degrees of the crankshaft rotation.

Two-stroke engines are more efficient in this respect, since they have 50% of the full cycle as power stroke and only 50% as "parasitic" stroke, therefore in a four cylinder two-stroke engine there will be four power strokes for full cycle (360 degrees of crankshaft rotation), meaning one power stroke every 90 degrees of crankshaft rotation. These allow for an overlap of the power strokes, creating a "continuous power", turning the crankshaft 360 degrees without the need for a flywheel.

Unfortunately two stroke engines are also inefficient for different reasons, being the main one the fact that they burn a mixture of fuel and oil. This calls for the need of a very efficient way of air scavenging to remove all the combustion gases from the combustion chamber, and this is not achieved in a standard two stroke engine. Several inventions have been patented to solve this problem, but none of them seem to offer a practical viability.

It is an object of my invention to provide a high efficiency, supercharged two stroke engine in which the limitations and disadvantages of the engines highlighted above are considerably reduced or eliminated altogether.

Description

According to this invention, with reference to drawing 1/2, there is provided a Supercharged Valveless Two-stroke Twin Injectors internal combustion engine, characterized by having a cylinder block 1 and a cylinder head 2 cooperating with one piston 3 reciprocally received in a cylinder 4 formed in said cylinder block to define at least one expansible combustion chamber 5, a plurality of circumferentially spaced round exhaust ports 8 through the wall of said cylinder uncovered by said piston near the end of its power stroke, and at least two specially designed injectors (as per drawing 2/2), each with an internal flow valve 1 and an external sealing valve 2, one injector 6 to inject pressurized air into said combustion chamber and one injector 7 to inject pressurized fuel into said combustion chamber, the air injector being fed from an external constant high pressure air compressor and the fuel injector being fed from an external constant high pressure fuel compressor, both injectors with means for being electronically controlled for opening and closing of their respective valves from an Electronic Management System Unit (which also controls a standard spark plug 9) working in synchronization with the position of the piston and the crankshaft rotation. The two injectors are fitted in the cylinder head by screw threads, facing the combustion chamber.

With reference to drawing 1/2, after ignition at TDC started by the spark plug 9, the piston 3 travels down in the power stroke. When the top face of the piston reaches the upper edge of the exhaust ports 8 in the wall of the cylinder 4, the exhaust phase starts. At this point the air injector 6 opens, compressed air enters the combustion chamber and continues to do so until the top face of the piston in its way up reach again the upper edge of the exhaust ports, closing them. The compressed air injected during the opening of the exhaust ports effectively scavenge all the burnt gases out of the combustion chamber, and the compressed air injection continues after the closure of the exhaust ports, at which point the fuel injector 7 opens, spraying compressed fuel into the combustion chamber mixing it with the clean air injected by the air injector. When the required mixture of air and fuel is accomplished both injectors close (not necessarily simultaneously), then the piston further compress the mixture in its way up the cylinder until it reaches TDC, where ignition occurs starting the next cycle.

The advantages of this invention are many-fold in comparison with a standard four-stroke engine: simple cylinder head with no valves, camshaft or any of the associated parts and no inlet manifold, making it easier and cheaper to manufacture, and much lighter in weight. More efficient, since as stated above it has four power strokes in one 360 degree rotation of the crankshaft, meaning more power delivered per consumed fuel and also higher torque.

Additionally, considering the simplicity and smaller mass of the cylinder head, this engine will be suitable for air cooling, furthering the simplicity of construction and also lowering manufacturing cost, since there will be no need for coolant chambers, cooling radiator, coolant pump and associated parts, making the engine still lighter. All these reduction in weight will increase the power output directed to the road wheels when the engine is fitted into a vehicle.

Furthermore, by using separate injectors for air and fuel makes this engine suitable for different types of fuel, like petrol, diesel or gas.

Drawing 1/2 shows a cylinder and cylinder head with air cooling fins. To take best advantage of this, a suggested design of this valveless twostroke engine could be four cylinders radially mounted on the crankcase, with cylinders being at 90 degrees of each other. This configuration will facilitate air cooling, will spread evenly the load on the crankshaft decreasing vibrations, it will also improve lubrication in the crankshaft ends.

Claims

1. A Supercharged Valveless Two-stroke Twin Injectors internal combustion engine, characterized by using two similar injectors, one for air and one for fuel, being these injectors (with reference to drawing 2/2) of a design suitable for direct injection into the combustion chamber and with means to be electronically controlled.

2. An engine as in claim 1, having a cylinder block and a cylinder head cooperating with at least one piston reciprocally received in a cylinder formed in said cylinder block to define at least one expansible combustion chamber, having at least one electronically operated air injector connected to a constant high pressure air compressor to inject air into said combustion chamber, at least one electronically operated fuel injector connected to a constant high pressure fuel compressor to inject fuel into said combustion chamber, a plurality of circumferentially spaced exhaust ports through the wall of said cylinder uncovered by said piston near the end of its power stroke, and a standard spark plug. Being the two injectors provided with screw threads to be fitted in the cylinder head facing the combustion chamber. Also means for controlling the air injector, the fuel injector and the spark plug in the form of an Electronic Management System Unit working in synchronization with the position of the piston and the crankshaft rotation.

3. An engine as in claim 1 and 2, characterized by means for injecting supercharged air into the combustion chamber after every power stroke while the exhaust ports are uncovered by the piston, for full scavenging.

4. An engine as in claim 1, 2 and 3 characterized by means of injecting supercharged air into the combustion chamber after the piston has closed the exhaust ports in the cylinder in its way up following the exhaust phase

5. . An engine as in claims 1, 2, 3 and 4 characterized by means of injecting pressurized fuel into the combustion chamber after the piston has closed the exhaust ports in the cylinder

6. . An engine as in claim 1,2,3,4 and 5, characterized by being able to use petrol, diesel, or gas as fuel.