AU2012100192A4 - Improved method of reducing fuel consumption of a petrol fuelled four stroke spark ignition engine by altering the engine manifold intake atmosphere by the induction of hot water vapour - Google Patents

Abstract

Water injection has been done for a long time with the main aim being power increase. Such water injection is done with ambient temperature water being sprayed into the inlet manifold. It was found that better results were obtained with high pressure spraying which gave a more highly dispersed spray with finer droplets of water. There were some claims of economy. The invention is to create a much finer dispersion of water by heating and causing the water to become steam/hot water vapour. This is achieved by injecting the water into a closed chamber/evaporator which is heated using the exhaust heat of the engine and inducting the produced steam/hot water vapour into the inlet manifold of the engine. The steam/hot water vapour has a much higher vapour pressure than the previously used ambient water spray and displaces a significant proportion of the incoming air as the inlet manifold pressure increases (or vacuum decreases). This causes less air to be drawn into the manifold and the engine management system consequently reduces the fuel being injected into the engine whilst maintaining the air to fuel ratio. The charge of fuel and air has thus been reduced which leads to improved fuel economy. The heat of the steam/hot water vapour induction also heats up and expands the air inside the inlet manifold which reduces the ambient air flow into the inlet manifold even further and results in a further slight reduction in fuel being injected by the engine management system. The injected fuel will be heated up and evaporated better and mixed with the inlet air, effecting better fuel/air charge preparation prior to combustion in the cylinders. It is common practice to run the engines with an excess of fuel to enable cooling of the engine to prevent the production of NOx gases. The extra fuel burns post cylinder in the exhaust manifold which can be seen by the colour of the exhaust pipe. Catalytic converters also need to be used to combust unburnt fuel. The invention provides the introduction of extra water vapour during the induction, compression and ignition strokes which takes over the role of cooling the engine. Using water to cool the engine is obviously a much more economic alternative than using expensive fuel. The mass of water vapour in the cylinder when heated and converted to superheated steam will produce a pressure increase in the cylinder which will increase the power of the engine. The engine can be described as a steam assisted internal combustion engine. If the mass of water exceeds the mass of fuel the engine may also be described as an internal combustion powered steam engine hybrid. The energy to produce the steam/hot water vapour is provided by the exhaust heat of the engine which means that the energy to create the steam/hot water vapour for the induction is not new energy but waste energy of the engine which reduces the energy loss through the exhaust pipe and contributes to engine efficiency. Figure 1 Control Schematic - Staged Manifold Vacuum vaporiser Flow Adjustment block Vapour to manifold Inlet manifold container PUMP12 4D -)4Vacuum line B+Diaphrag Battery

Description

2 3 FEB 2012 AUSTRALIA Patents Act 1990 COMPLETE SPECIFICATION INNOVATION PATENT IMPROVED METHOD OF REDUCING FUEL CONSUMPTION OF A PETROL FUELLED FOUR STROKE SPARK IGNITION ENGINE BY ALTERING THE ENGINE MANIFOLD INTAKE ATMOSPHERE BY THE INDUCTION OF HOT WATER VAPOUR. The following statement is a full description of this invention, including the best methods of performing it known to us: 1 Improved method of reducing fuel consumption of a petrol fuelled four stroke spark ignition engine by altering the engine manifold intake atmosphere by the induction of hot water vapour. Description 5 Water injection into internal combustion engines has been done for many years. Main objectives in spraying water included increase in power of the engine and effective increase in octane rating of the fuel used. Methods have included drawing air through water to pick up moisture and spraying water into the air intake and inlet manifold. It is known that it is necessary to create fine particles of water to facilitate the internal combustion process. 10 Water particles that are too big can interfere with the combustion process causing rough running of the engine. Droplets that are too large can coalesce to form liquid water when a surface is impinged. High pressure spraying has been found to give finer particle sizes. The water particles in the spray are cold and do not cause any appreciable change in vapour pressure and hence the vacuum level in the inlet manifold is not affected significantly. 15 The purpose of this innovation patent is primarily focussed on fuel economy in petrol engines. Techniques to reduce the amount of fuel whilst maintaining normal running of the engine at adequate power levels will be discussed. It has been observed that the water content of high temperature air at high humidity contains appreciable quantities of water. The chart (Figure 3) shows the weight of water in 20 grams per kilogram of air at 100% humidity over a range of temperatures. At 40degC the water content is 50 grams per kilogram of air and at 50degC the water content is 95 grams per kilogram of air. Engines continue to run under such conditions meaning that these levels of water ingestion are feasible without detrimental effects on the engine. The mass of fuel injected into an engine that operates at a nominal fuel consumption level of say 8 litres per 25 100 kilometers running at 100 kph is about 6000 grams per hour (specific gravity of gasoline is 0.7 to 0.77) or 100 grams per minute. At lower speeds the mass is relatively less. At 80kph the fuel usage would be about 80 grams per minute. These are nominal figures. The air intake needed to burn 80 grams per minute of fuel is about 1000 grams (for 200 grams content of oxygen). If the air was at 100% humidity and 50degC the water content would be 30 nominally 95 grams and of the same order as the weight of the fuel. It can be deduced that engines are capable of ingesting weights of water at similar rates at which weight of the fuel is being burned. Water may be introduced into the engine in such quantities by evaporating water in a closed chamber which acts as an evaporator which has been placed in the flow of the 35 exhaust gas of the engine and thus heated by the exhaust gas. A conduit which joins the chamber/evaporator to the inlet manifold guides the evaporated hot water vapour into the inlet manifold. The temperature of the chamber/evaporator is nominally 200degC to 2 450degC so that water introduced is flashed off immediately as steam/hot water vapour. The temperature of the steam/hot water vapour will be near to 100degC as it flashes off and enters the inlet manifold. The amount of steam which may be produced is more than is possible simply by spraying. The amount of steam may be increased by increasing the 5 amount of water into the chamber/evaporator until the heat transfer capacity of the chamber/evaporator being heated in the exhaust has been reached. Since large quantities of exhaust energy are available large amounts of steam may be generated. The capacity of the spraying of ambient water is limited by the tendency of the spray to coalesce to liquid water at higher volume levels. Steam may also be generated in a sealed 10 chamber/boiler which develops pressure and delivered at higher rates and pressures into the inlet manifold. The steam/hot water vapour provides a vapour pressure which causes the pressure in the inlet manifold to increase. A significant drop in the vacuum level of the inlet manifold is observed. This lower vacuum level causes a reduction in the air intake volume. The air 15 intake has been effectively displaced by the effect of the steam/hot water vapour intake. The computer management system will reduce the amount of fuel being injected to balance with the oxygen/air intake. Less fuel is now being consumed whilst maintaining the air fuel ratio balance. The fuel has been reduced without creating a lean burn situation. The heat from the steam/hot water vapour will also heat the incoming air and expand it and hence 20 reduce the airflow even more. This will lead to a further (slight) reduction in air intake and subsequent reduction in fuel injection when adjusted by the engine management system. This will tend to improve fuel economy further. The steam/hot water vapour provides heat which heats the inlet manifold heating both the intake air and the fuel which is being injected. The heating of the fuel encourages efficient 25 vaporisation of the fuel turning it into a gas/vapour form which then mixes efficiently with the intake air and making it ready for combustion. (Efficiency improvements in fuel economy have been achieved by others with higher pressure injectors which atomise the fuel more). Very effective atomisation/gasification has thus been effected by the use of heat and an evaporation process. The fuel is now well prepared for ignition. The steam/hot 30 water vapour has lost some energy and is somewhat less than 100degC and is now probably better described as simply hot water vapour. The hot water vapour/fuel/air mix enters the engine and is ignited. The temperature in the cylinder increases dramatically and quickly as the combustion takes place. At the temperatures reached in the cylinder the water vapour changes to superheated steam and 35 becomes more of a gaseous state. The full nature of the physical state of water over a large temperature range is not fully understood. Water at 100degC will have a large number of water molecules as agglomerates (H20)n, where n is a large number with an effective large molecular weight. Superheated steam may exist as single water molecule (H20) with an effective low molecular weight of 18 (H=1 and 0=16). The gram molecular volume of H20 3 (18 grams) at STP is 22.4 litres. The hot water vapour (H20)n which has some vapour pressure thus changes to a much higher pressure water (H20) gas at the high temperatures in the cylinder. This increase in pressure will increase the power output of the engine. The energy to achieve this conversion of hot water vapour to superheated steam will cool 5 the cylinder. Cooling of the cylinder is thus achieved by inexpensive water instead of excess fuel which is the normal practice to avoid engine overheating. The cooling is done to avoid the formation of NOx gases which are acidic pollutants. The protective cooling of the cylinders and avoidance of NOx gases is thus achieved with inexpensive water injection instead of expensive fuel. The present practice of using excess fuel for cooling is evidenced 10 in the burning of the excess fuel in the exhaust manifold which can be seen as increased temperatures in the exhaust manifold and the design need for catalytic converters which are needed to burn the excess fuel. The steam/hot water vapour injection thus acts both as a heating agent and cooling agent. It heats the fuel which is at ambient temperatures and cools the gases of combustion and the 15 cylinder which reach very high temperatures. The addition of a significant level of water vapour similar to that which is added when the engine runs under very high atmospheric temperature (up to 50degC) at very high humidity (up to 100% humidity) is achieved with the engine running under ambient temperature and humidity conditions. 20 The amount of steam/hot water vapour added in the innovation is potentially much more than when water spray is used for power increase. When used to increase power enough water is added to reduce the detonation of the fuel and effectively increase the octane rating of the fuel. The high rate of fuel usage and moderate use of water gives a higher fuel to water ratio than when economy is the prime purpose. The extra fuel will tend to be the 25 more important factor in cooling the engine and reduce the tendency for NOx to form. When the purpose is increased economy as much steam/water vapour is added as possible whilst maintaining the running of the engine. The lower rate of fuel usage and increased use of water gives a much lower fuel to water ratio than compared to when power increase is the prime purpose. As more hot water vapour is added the fuel injected is reduced by the 30 engine management system. The cooling effect of the hot water vapour becomes the more important factor in cooling the engine and reducing the tendency for NOx to form. The high rate of steam/hot water vapour injection provides a significant increase in mass in the cylinder which is more than is achievable with spraying water so that more pressure increase in the combustion cycle will be achieved. This steam pressure assist of the internal 35 combustion engine may be likened to having and internal steam engine working alongside the internal combustion engine and in the same engine and may be described as an internal 4 combustion steam assist engine. If the mass of water becomes significantly more that the mass of fuel the engine may be described as an internal combustion steam engine hybrid. Other positions for the steam entry to the motor have been considered. If steam is introduced after the mass airflow sensor and before the throttle butterfly there are two 5 perceived problems. The throttle body will be exposed to abnormally high temperatures. Attached to the throttle body is the throttle position sensor that is usually a plastic housing containing a sensitive variable voltage device that sends information to the engine management unit. The expansion of the incoming air between the mass airflow sensor and the throttle body 10 will require that the throttle be more open than for the same air mass at normal temperatures. This will be incorrect information from the throttle to the engines ECU and may deliver an increased fuel injection result. There will be more cooling of the steam/hot water vapour compared to direct injection into the inlet manifold so that the temperature may be lower at the point where mixing occurs 15 with the fuel. This may cause a lower evaporation rate of the fuel. Since efficient vaporisation of fuel is desired it is preferred to place the steam/hot water vapour injection point closer to the fuel injection point than the throttle body. The objective is for the hot water vapour to heat the fuel preferentially to evaporate the fuel before heating the incoming intake air (at a slightly lower temperature). Evaporating the fuel effectively will 20 cause a fuel vapour pressure which will add to the hot water vapour pressure which will reduce the vacuum in the inlet manifold further so reducing the air intake which consequently reduces the fuel injected further to give more fuel economy. Other methods of raising steam for induction have been considered. They include separately fired boiler or vaporiser units and electrically heated units. The use of the 25 exhaust waste heat allows some of this wasted exhaust heat to be recovered and utilised in better preparing the incoming air/ fuel charge for combustion. Preferred Embodiments Initial work was done using a water spray method using the inlet manifold vacuum to control. The purpose of this work was to establish water injection amounts that were 30 feasible and possibly limits to the amount of water that the engine could tolerate. Some economy in fuel usage was observed during these trials. These water injection rates were established and the system converted to a steam/hot water vapour injector. Solenoid valve control diagrams and operation of steam control by staged manifold vacuum (Figure 1). 35 Shown is a simple water circuit from a container to a pressure limited water pump. Water under pressure is carried to two solenoid valves.

5 The output side of both of the valves are piped to a metering block where the output of each valve can be controlled by a needle screw. From the needle screws the metered water is taken from a common gallery to the vaporisation chamber. This is a sealed vessel with one outlet directly to the inlet manifold of 5 the engine. Control of the solenoid valves is arranged in three stages according to the level of vacuum in the inlet manifold- both off, one on, both on. The control device is a vacuum diaphragm whose force is opposed by a tension spring set so that over the range of vacuum in the inlet manifold a range of travel on the diaphragm arm 10 can be utilised. Two separate positions on this travel are selected for the operation of two micro switches. They each carry power to energise one of the solenoids via a relay (not shown). The effect is that under idle or high vacuum conditions both solenoid valves are off. Under light load conditions only one solenoid is on. 15 Under heavy load conditions both solenoids are on. It was observed that the water injection into the evaporation chamber was performed successfully and that steam/ hot water vapour was produced and injected into the inlet manifold as the engine operated at vacuum levels corresponding to light and heavy load conditions. It was also observed that for a significant proportion of the running time of each 20 test run the engine was under idle or high vacuum with no injection into the evaporation chamber which meant that no steam/hot water was being injected at those times and the engine was running as normal. Significant fuel savings were achieved even though the water injection and steam/hot water vapour production was off under conditions of higher vacuum levels. 25 When steam/hot water vapour was injected into the inlet manifold the water vapour produced created a vapour pressure which resulted in the vacuum of the manifold to run at lower vacuum compared to the previous observations with water spray only. This gave a good indication that the air inlet rate was being reduced by this displacement mechanism. 30 Operation of steam control by a digital pulse adjuster (Figure 2) The control of the steam/hot water vapour was changed to allow control over the full range of engine operation from just off idle to maximum. Injection of steam/water vapour for a much greater percentage of time of the operation of the engine produced improved b economy of fuel usage. The operation of the steamer was integrated into the engine management system of the vehicle. Shown is a simple water circuit. Water is taken from a container to a pressure limited water pump. Water under pressure is carried to a single solenoid valve. Its output is piped directly 5 to the vaporising chamber. The vaporising chambers only outlet leads directly to the inlet manifold of the engine. Control of the solenoid valve is linked to the operation of the engines fuel injector system by a digital pulse adjuster. The amount of water admitted to the vaporiser is determined by the length of time the solenoid valve is on in a period of time where a square wave signal is fed 10 to the solenoid. This is pulse mode modulation. The basic pulse rate comes from the engines management unit to drive the fuel injectors. The digital pulse adjuster senses the rising edge of the injectors pulse. A programme in the pulse adjuster memorizes the operation of the fuel injectors action over its full range. This is then broken up into 128 segments that can be individually selected and 15 displayed on a screen. These are called load points. At each load point the adjuster allows the time the solenoid is on to be varied either up or down from the time the fuel injector pulse is on. This is called mapping. The variation away from the fuel injector's time pulse is completed for each of the 128 steps in the programme and then locked in.

Claims (5)

1. Fuel usage is reduced by the induction of hot water vapour into the inlet manifold which decreases the inlet manifold vacuum due to the vapour pressure of the hot 5 water vapour and the vapour pressure of the evaporated fuel to displace intake air and hence reduce the air flow and consequently cause the engine management system to reduce the fuel injected.

2. The hot water vapour induction causes heating of the injected fuel and more 10 efficient evaporation of the fuel making it better dispersed and prepared for ignition and more efficient combustion.

3. The hot water vapour induction provides a significant amount of water which is predominant in cooling the cylinder during the induction, compression and ignition 15 strokes and contributes significantly to the reduction of NOx pollutants.

4. The hot water vapour induction becomes superheated steam during the ignition cycle which provides an increase in pressure which increases the power of the engine which may be described as an internal combustion steam assist engine. 20

5. The energy to produce the hot water vapour is provided from the exhaust heat of the engine which is then converted to mechanical energy so improving the efficiency of the engine. 25 KENNETH GREEN 22 FEBRUARY 2012 GRAHAM EDWARD THOMS