GB2361265A

GB2361265A - I.c. engine with steam power stroke

Info

Publication number: GB2361265A
Application number: GB0008960A
Authority: GB
Inventors: Matthew Harker
Original assignee: Individual
Current assignee: Individual
Priority date: 2000-04-13
Filing date: 2000-04-13
Publication date: 2001-10-17
Also published as: GB0008960D0

Abstract

A four-stroke reciprocating-piston i.c. engine includes a steam generator 5 in which water is converted to steam by the heat of the exhaust gases discharged from the cylinder 1. The steam is introduced via a steam valve 6 into the cylinder in the stroke normally used for induction to provide an additional power stroke. A substantial part of the energy which would have been lost to the atmosphere as heat in a conventional i.c. engine is thus recovered. Steam exiting the cylinder passes through a condenser 7 from which the water is pumped to a header tank 10 linked to the water jacket 3. The condensation of the steam reduces the pressure in the cylinder to below atmospheric pressure, drawing the fuel/air mixture into the cylinder without needing movement of the piston. On starting, the engine operates on a conventional four-stroke cycle with the inlet valve opening at the start of the induction stroke; when the engine has reached its working temperature the timing of the inlet valve is changed so that it opens at the end of the steam stroke.

Description

2361265 INTERNAL COMBUSTION ENGINES

Field of the Invention

This invention relates to internal combustion engines and has for its object the provision of an improved form of internal combustion engine which includes means for utilising the energy of the hot exhaust gases discharged by the engine.

Owing to the high temperature produced in the cylinder of an internal combustion engine, a partial cooling of the cylinder is a necessity and this cooling results in a waste of heat. Less than a quarter of the heat energy developed in an internal combustion engine is converted into useful work. The remainder of the heat has to be dissipated in order to prevent any part of the engine from becoming so hot that it ceases to work. It has been estimated that, for a typical internal combustion engine at full throttle, 36% of this heat passes out of the exhaust system, some 7% is lost to internal friction and heating the lubricating oil, and a further 33% is dissipated in the cooling system.

2 In a steam engine, the steam loses heat to the cylinder, but the cylinder temperature never becomes too high and no cooling is necessary. In fact, the steam in the cylinder would work more efficiently if the cylinder were kept hotter than the steam.

These and other considerations suggest that it would be an advantage to combine an internal combustion engine and a steam engine in one prime mover. It is accordingly a specific object of the present invention to do this.

Summary of the Invention

According to a first aspect of the present invention there is provided an internal combustion engine which includes a piston movable within a cylinder in a given direction during a power stroke and in which means are provided for effecting controlled introduction of steam into the cylinder to move the piston in said given direction.

According to a more specific object of the present invention there is provided an internal combustion engine which includes a piston movable within a cylinder, means for introducing a fuellair mixture into the cylinder, a water jacket surrounding the cylinder, a steam generator within which water from the water jacket travels in heat exchange relationship with hot exhaust gases discharged from the cylinder and is converted into steam, and means for effecting controlled introduction of the steam into the cylinder on the same side of the piston as the fuellair mixture is introduced.

3 Brief Description Of the Drawin_q

The single figure of the drawing shows the essential parts of the engine.

Description of the Preferred Embodiment

As shown in the drawing, the engine includes a cylinder 1 within which a piston 2 is arranged for reciprocal movement, the piston 2 being provided with sealing means for engagement with the wall of the cylinder and connected by means of a connecting rod 11 to a crankshaft 12.

The cylinder 1 is contained within a water jacket 3 through which water is pumped by means of a water feed pump 4. The water flow path includes a steam generator 5 through which water from the jacket 3 is caused to flow in heat exchange relationship with the hot gases issuing from the cylinder 1. Steam is generated in the steam generator 5 and this steam is introduced, under the control of a steam throttle, into the top of the cylinder 1, as described below.

Steam exiting from the cylinder 1 passes through a condensor 7 where it is converted back to water and from there it is pumped by an extraction pump 9 to a header tank 10 which is linked to the water jacket 3.

4 The supply of the fuellair mixture into the cylinder 1 is controlled by a carburettor 8 and the engine will be provided with a sparking plug, timing gear, etc. for effective operation in the manner described below.

When the engine is started from cold, there is no steam available so that the engine must run on the conventional 4-stroke cycle, i.e. induction, compression, power and exhaust. During this period there is only one stroke, i.e. the power stroke, in which useful work is done. When, however, the working temperature has been reached, the engine cycle changes to make use of steam in addition to the original fuel. The engine still operates on a 4-stroke cycle, but in a significantly different way.

The hot water from the steam jacket 3 is pumped into the steam generator 5 by the water feed pump 4. The hot exhaust gases pass through the steam generator 5 in heat exchange relationship with the water and converting it to steam. When most of the heat has been extracted from the combustion products, they are discharged into the atmosphere. A substantial part of the heat energy that would otherwise have been lost to the atmosphere is thus recovered so that it can be converted to mechanical energy, in the engine, in the form of a steam expansion stroke.

The engine now has two power strokes, one from combustion and one from steam. To keep the cycle within four strokes, one operation of the initial 4-stroke cycle must give way to allow for the use of a steam stroke. The steam expansion uses a downward stroke, namely that normally used for induction. Induction is now achieved by exhausting the used steam into the condenser 7 at the end of the first downward stroke. Condensation of the steam lowers the pressure in the cylinder 1 to below atmospheric pressure, drawing the fuellair mixture into the cylinder 1 without needing movement of the piston 2. Thus, exhausting of the steam and induction of the fuellair mixture is achieved, in one operation, when the piston 2 is moving slowly at the end of this downward stroke.

The remaining three strokes of the 4-stroke cycle continue as for a normal internal combustion engine, i.e. compression, combustion power and combustion exhaust, returning to the first stroke as detailed above. In order to change the engine cycle, means are provided whereby the time of opening of the inlet valve to introduce fuel into the cylinder 1 is changed once the working temperature is reached.

Once the working temperature has been reached and the engine is operating in the combined mode, the inlet valve must remain closed during the steam stroke, opening at the end of this stroke so that the condenser action draws the fuel into the cylinder 1. When the engine begins to run, i.e. in the internal combustion only mode, the inlet valve must be opened at the start of the induction stroke so that the downward movement of the piston 2 draws the fuel into the cylinder 1.

When the engine is operating the 4-stroke steam cycle, the sequence of operations is as follows:- 6 1) First Stroke - Steam Power Stroke Starting with the piston at top dead centre (T. D. C.), the steam valve 6 is opened. The steam pressure forces the piston 2 downwardly within the cylinder 1. The steam valve 6 is closed mid-stroke to allow for steam expansion. This is the first power stroke in the cycle.

2) Second Stroke - Compression The steam exhaust valve is opened to the condenser 7 a few degrees before bottom dead centre (B.D.C.). Condensing the steam to water lowers the pressure in the cylinder to below atmospheric pressure. This causes the induction of the fuellair mixture into the cylinder 1. The piston 2 is now moving up the cylinder 1. The inlet valve is closed and the fuellair mixture is compressed.

3) Third Stroke - Combustion Power Stroke At the end of the compression stroke, the fuellair mixture is ignited. Combustion increases the temperature and the pressure forcing the piston 2 down the cylinder 1. This is the second power stroke in the cycle.

4) Fourth Stroke - Exhaust The piston 2 returns up the cylinder 1 with the exhaust valve open, expelling the burnt gases from the cylinder 1 through the steam generator 5, thus increasing the temperature and pressure of the steam. At the end of this stroke, the exhaust valve closes and the 7 steam valve 6 re-opens for the next steam power stroke and the cycle is repeated.

As compared with a conventional internal combustion engine, an engine in accordance with the present invention has the following advantages:- a) the higher mean temperature of the engine makes the combustion cycle more efficient, b) no mechanical energy is taken from the engine for the induction process - the energy comes from the exhaust steam, c) the cycle provides a working stroke for each revolution of the crankshaft - this gives a more uniform turning moment on the crankshaft reducing the size of the flywheel which is required, d) there is less wear and tear on the reciprocating parts due to a more constant pressure in one direction on the piston, e) the steam generated by the heat extracted from the combustion cycle:- 1) increases the power of the engine without increasing the consumption of fuel, 2) cools the cylinder and the piston since it absorbs heat during expansion, and 8 3) suffers no condensation loss in the working cylinder, and f) only a small amount of steam needs to be generated as it is only required on alternate power strokes.

Although the invention has been described in detail above as applied to an internal combustion engine which includes a reciprocating piston, the invention is equally applicable to an engine having a rotating piston.

9

Claims

Claims:-

1. An internal combustion engine which includes a piston movable within a cylinder in a given direction during a power stroke and in which means are provided for effecting controlled introduction of steam into the cylinder to move the piston in said given direction.

2. An internal combustion engine which includes a piston movable within a cylinder, means for introducing a fuellair mixture into the cylinder, a water jacket surrounding the cylinder, a steam generator within which water from the water jacket travels in heat exchange relationship with hot exhaust gases discharged from the cylinder and is converted into steam, and means for effecting controlled introduction of the steam into the cylinder on the same side of the piston as the fuellair mixture is introduced.

3. An internal combustion engine constructed and arranged to operate substantially as hereinbefore described with reference to and as shown in the accompanying drawing.