GB2077853A

GB2077853A - I.C. Engine with Power Stroke Cooling Fluid Injection

Info

Publication number: GB2077853A
Application number: GB8116377A
Authority: GB
Original assignee: Individual
Current assignee: Individual
Priority date: 1980-06-12
Filing date: 1981-05-28
Publication date: 1981-12-23

Abstract

Water is injected subsequent to combustion to absorb heat and produce additional power. The water may be injected on the fourth stroke of a six-stroke cycle just after partial exhaust, the fifth stroke effecting compression of the steam and exhaust gas mixture and the sixth stroke providing a second power stroke.

Description

SPECIFICATION Engine The invention relates to a reciprocating internal combustion engine. There are basically two types of heat expansion engines:-- external dbmbustion and internal combustion engines.

The external combustion engine generates pressure from an external source (e.g. steam boiler) and uses the expanding energy of the steam, to convert to motion. The efficiency of this type of engine is dependent on the retention of heat and is achieved by the compounding of cylinders, insulation, heat exchangers and the like.

The internal combustion engine develops its power by the sudden release of energy when fuel is burnt under pressure in a confined space. After the release of this energy (Power Stroke), the efficiency of this engine depends on the quick release of this excess heat (i.e. water cooling, radiation and exhaust gases). With the most efficient internal combustion engines, 60% of the heat generated is wasted.

In a four-stroke internal combustion engine (Otto Cycle), the power impulse is succeeded by three non-power strokes. Air is first saturated with the quantity of fuel needed for combustion, when it is drawn into the cylinder on the induction stroke and then compressed on the compression stroke. The compressed mixture is ignited and burnt at a constant volume. The highly heated air is then allowed to expand, pushing the piston down until the air has reached its original volume.

The exhaust valve is then opened and the rising piston pushes out the hot spent gases.

It is at the exhaust stroke of an engine that the main loss in heat occurs. The heat given up to the cooling water of the engine at this period increases rapidly, because, in additionto the normal heat flow to the cylinder walls, the hot gases are passing at high velocity through the exhaust valve and through a short length of pipe.

There could also be a 90 degree bend in this pipe which could be cooled by the water circulation of the engine.

When tests were carried out by Sir Harry Ricardo, he found that, of the total heat taken up by the cooling water in a water-cooled engine, more than 50% is given up during the exhaust stroke.

In a standard internal combustion engine, at a 5:1 compression ratio, 32% of the total heat of the fuel works on the piston, 28% of the total is carried away by cooling water and 40% is lost through the exhaust The same engine will have a combustion temperature of about 2,500 degrees centigrade and at the end of the expansion stroke the temperature will still be over 1,700 degrees centrigrade. This will drop dramatically during the exhaust stroke as the cylinder and block are heated.

An object of the present invention is to reduce this great loss of potentially useful energy, and to provide an engine modified so that some of this heat can be converted to mechanical energy.

Accordingly the invention provides a reciprocating internal combustion engine having means whereby a cool fluid can be introduced into a cylinder of the engine subsequent to combustion to absorb heat from the combustion gases and form a mixture from which additional energy can be applied to a piston of the engine.

Preferably the fluid is introduced during a fourth stroke of the engine to absorb heat from the combustion gases and the mixture is allowed to expand in a fifth stroke to impart further energy to the piston and is exhausted in a sixth stroke.

The liquid can be water.

The liquid can also be introduced at or about the end of the expansion stroke and the beginning of the fourth (normal exhaust) stroke so that a reduction in pressure occurs during the exhaust stroke and the partial vacuum created draws the cylinder towards the cylinder head during a part of the exhaust stroke.

The liquid can be injected immediately after the ignition of the change in the cylinder and still have a similar advantageous effect.

The basic improvement to the engine could be brought about by the modification of the valve gear, so that the engine cycle becomes a 6 stroke cycle instead of the normal 4 strokes, with the last 2 strokes using the waste heat to generate steam and power as in a steam-engine.

The order of work would then be: 1) induction stroke 2) Compression stroke 3) Expansion stroke (Ignition) 4) Partial exhaust 8 water injection stroke 5) Steam expansion stroke 6) Steam exhaust stroke.

The invention will be described further, by way of example, with reference to the accompanying drawing, wherein the single figure illustrates, schematically the operating cycle of a preferred single cylinder engine conforming to the present invention.

A preferred engine of the invention is similar in many respects to a conventional engine, having a cylinder head 10 including an inlet valve 1 and an exhaust valve 12; a cylinder 13, piston 14, crankshaft 1 5 and crankcase 1 6. There is also an injector, not shown, whereby water can be injected into cylinder 1 3 in accordance with the operating cycle of the engine which will now be described. The appropriate strokes of the cycle are numbered 1 to 6.

The first three cycles (induction (1), compression (2), and expansion (3)) are as in a conventional engine but, when the exhaust valve 12 is opened just before the piston 14 has completed its expansion stroke (valve overlap) the excess pressure of the combustion gases in the cylinder 1 3 will rush out through the exhaust port and it is then given extra momentum by the rising piston 14. At this moment the exhaust valve 12 is snapped shut, causing the rapidly accelerating gas to swirl in the top of the cylinder head 10. At the same time water is injected into the swirling mass. The heat in the gas is rapidly absorbed by the water and there is also a rapid reduction in the volume of the gas on account of the sudden reduction in temperature.

At this stage there is a delay period between the absorption of the heat by the water and its conversion to steam. When the state of equilibrium is reached, the steam releases its energy by expanding. The timing and quantity of water injected can be advanced or retarded so that equilibrium occurs when the piston 14 has reached the top of its stroke. The expanding steam is then allowed to push the piston 14 down until it has reached the bottom of its stroke, when the exhaust valve 12 opens and the expanding steam is expelled by the rising piston 1 4. Other advantages are: (1) Because of internal cooling by water injection, no water cooling of the outside of the engine is necessary and it would, in fact, be advantageous to insulate the outside of the cylinder(s) in order to retain as much heat as possible.

(2) The injected water can be pre-heated from the steam in the exhaust to give high thermal efficiency.

This system can also be applied to all reciprocating compression ignition engines, (e.g.

diesel).

As a variation on the above, the liquid can be injected immediately after ignition so that it mixes with and cools the expanding gases, at the same time vapourising to increase the pressure in the cylinder and thus the power of the stroke. Cooling of the cylinder walls is enhanced and the vapour dilutes the exhaust gases.

Claims

1. A reciprocating internal combustion engine having means whereby a cool fluid can be introduced into a cylinder of the engine subsequent to combustion to absorb heat from the combustion gases and form a mixture from which additional energy can be applied to a piston of the engine.

2. An engine as claimed in claim 1 wherein the fluid is introduced during a fourth stroke of the engine to absorb heat from the combustion gases and the mixture is allowed to expand in a fifth stroke to impart further energy to the piston and is exhausted in a sixth stroke.

3. An engine as claimed in claim 1 or 2 wherein the liquid can be water.

4. An engine as claimed in claim 1, wherein the liquid is introduced at or about the end of the expansion stroke and the begining of the fourth (normal exhaust) stroke so that a reduction in pressure occurs during the exhaust stroke and the partial vacuum created draws the cylinder towards the cylinder head during a part of the exhaust stroke.

5. An engine as claimed in claim 1, wherein the liquid is injected immediately after the ignition of the change in the cylinder

6. An engine as claimed in claim 2, wherein the engine valve gear, is modified so that the engine cycle becomes a six stroke cycle instead of the normal 4 strokes, with the last two strokes using the waste heat to generate steam and power as in a steam-engine, the order of work then being.

1) Induction stroke; 2) Compression stroke; 3) Expansion stroke (Ignition); 4) Partial exhaust and water injection stroke; 5) Steam expansion stroke; and 6) Steam exhaust stroke.

7. An internal combustion engine substantially as hereinbefore described with reference to and as illustrated in the accompanying drawing.