DESC:MULTI PHASE INJECTION SYSTEM AND METHOD
FIELD OF THE INVENTION
The present invention relates to combustion engines and more specifically to a fuel injection method to increase power output, and to make an engine fuel tolerant i.e. where the fuel is injected as vapor, liquid, or a combination thereof.
BACKGROUND OF THE INVENTION
Combustion engines are very popular throughout the world. They are valued for their power, convenience, price, size, reliability, and other subjective factors (power delivery, sound, serviceability, etc.). Due to concerns over the environment, stricter emission regulations and ever-increasing fuel prices, cleaner alternatives and more efficient engine designs are the need of the hour. Each engine is designed to operate efficiently with a particular fuel or a narrow range of fuels with similar characteristics, hence limiting functionality with available or better fuels. Conventional engines have lower efficiency due to various reasons including but not limited to – incomplete combustion, poor scavenging, leakages, frictional losses, compression losses, head loss in conduits and turbulence losses. A factor which affects the maximum power output of a combustion engine is its rotational speed. Speed of internal combustion engines, specifically Compression Ignition (CI) engines are limited by the time required for compression, if this constraint is overcome, the engine will be able to run at higher speeds and hence producing higher power. Such an engine will be able to produce similar power compared to a low-speed higher capacity engine while being smaller and lighter, while consuming a lower quantity of fuel per unit of power produced and as a consequence reducing emissions. As of 2022, much research is being done in the field of alternative fuels for combustion engines. It would be unwise to hope that current engines will work efficiently with future fuels, hence development of a fuel tolerant engine along with newer fuels is necessary.
Summary of the invention
Disclosed herein is a system and method primarily for improving the power output of a combustion engine, and secondarily to make the engine fuel-tolerant and more efficient.
This method according to the invention relates to a combustion engine with at least one combustion chamber, intake valve, exhaust valve, inlet port, exhaust port, fuel injector, charge exciter (example spark plug) and engine cooling system. The engine described is capable of working with conventional mechanically actuated valves, but electronically actuated valves will improve the engine’s capabilities.
Preferably, a compressor is used to compress air to pressure greater to 15 bar (ideally > 35bar), the compressed air is then stored in a suitable storage tank. This compressed air is used as the fuel oxidant (, and can be used for the working of a pneumatic actuator).
When a liquid fuel (gasoline(petrol), diesel, etc.) is used, the engine is started as a conventional combustion engine. When the engine warms up, some fuel is converted to vapor, preferably by pumping the fuel through secondary passages built into the engine block, cylinder head, etc. In this passage, the fuel absorbs heat, evaporates and converts to vapor state. The liquid fuel may also be vaporized by utilizing a heat exchanger, heat pipes (, etc.) to transfer heat from the engine block and/or cylinder head and/or engine cooling system and/or exhaust fumes to the liquid fuel.
Preferably, the vaporized fuel is compressed using another compressor and stored in a temporary tank.
Preferably, the compressed air is made to flow to the intake manifold through a solenoid-controlled valve and excess air is ejected out such that pressure drops to the required value (or compressed air is expanded to the required pressure). Compressed air is then lead to the combustion chamber.
The compressed vaporized fuel and/or liquid fuel is injected into the inlet port through separate injectors (ideally a single injector which can safely inject fuel in both vapor and liquid state (not mentioned)). A lean fuel-air mixture is formed in the inlet port. This lean mixture is sucked into the combustion chamber during the suction stroke and is the compressed in the following compression stroke.
Preferably, near the end of the compression stroke and/or near the start of the power stroke, a small quantity of atomized liquid fuel is sprayed into the combustion chamber and/or compressed vaporized fuel is injected into the combustion chamber.
The charge exciter (spark plug) is powered to aid in ignition of the air-fuel mixture during the power stroke. The piston is hence pushed down.
The cycle is repeated. Based on input from engine sensors (pressure sensor, temperature sensor, oxygen sensor, etc.), the parameters listed below can be varied such that efficiency and/or power output is higher.
• the quantity of fuel injected (vapor or liquid) in the inlet port or/and combustion chamber
• pressure and quantity of compressed air
• air-fuel ratio
• valve timings
Essentially, the engine control unit varies the parameters in a trial-and-error manner to find the most suitable values for maximum efficiency and/or power output.
The gaseous combustion products are ejected through the exhaust port. The exhaust fumes may be forced to expand through a turbine, keyed to any or both of the aforementioned compressors, as a secondary input, the primary being an electric motor.
Since the oxidant and fuel are compressed separately, and their pressure can be varied as needed, the engine can run with different fuels, or combination of fuel after a few combustion cycles.
Preferably, when only a gaseous fuel is used, the fuel may be compressed to a higher pressure and then stored in the temporary tank, or directly transferred to the temporary tank. The fuel from the temporary tank may be injected in the intake port only, injected in the combustion chamber only, or injected in both in required quantity. The working of such an engine will be similar to the working of a four-stroke conventional combustion engine.

Based on above literature, the working of an engine when both liquid and gaseous fuel is used can be interpreted as the gaseous fuel is injected through the vapor injectors and the liquid fuel is injected through liquid injectors into the inlet port and/or combustion chamber in required quantity.

Brief description of drawings
Figure-1 shows a schematic diagram of the system
Component Name/ Description
1 Liquid fuel tank
2 Liquid fuel filter
3 Liquid fuel pump – 1
4 Liquid fuel pump – 2
5 Vapor fuel Compressor
6 Temporary tank for storing compressed vaporized fuel or compressed gaseous fuel
7 Gaseous fuel tank
8 Gaseous fuel compressor
9 Condenser
10 Expansion valve
11 Secondary liquid fuel tank
12 Liquid fuel pump – 3
13 Air filter
14 Air compressor
15 Compressed air storage tank
16 Solenoid controlled pressure relief valve
17 Solenoid valve
18 Solenoid valve
19 Solenoid controlled throttling valve
20 Solenoid valve
21 Solenoid valve
22 Solenoid valve
23 Solenoid valve
24 Solenoid valve
25 Solenoid valve
26 Liquid fuel filter
100 Combustion engine

Figure-2 shows a detailed section of combustion engine shown in FIG 1 as component 100
Component Name/ description
101 Engine block
102 Cylinder head/Cylinder block
103 Combustion Chamber
104 Piston
105 Connecting rod
106 Inlet port
107 Vapor fuel injector (Port injector)
108 Liquid fuel injector (Port injector)
109 Inlet valve
110 Vapor fuel injector (Direct injector (injection into combustion chamber))
111 Liquid fuel injector (Direct injector (injection into combustion chamber))
112 Exhaust valve
113 Exhaust port
114 Charge exciter (Spark plug)
115 Passage for conversion of liquid fuel to vaporized fuel

Detailed description of preferred embodiments
Reference is made to Figure-1, and Figure-2. The combustion engine 100 (FIG-1) consists of an engine block 101, cylinder head 102 with at least one combustion chamber 103. The engine may have multiple combustion chambers, arranged accordingly (V, inline, boxer, etc.). It should be noted that the method and equipment mentioned is applicable to an embodiment where the combustion engine has multiple combustion chambers.
It should be noted that there are multiple pressure sensors, temperature sensors, oxygen sensors, torque sensors, force sensors, displacement sensors. are placed throughout the engine, which are not shown.
The combustion engine 100, consists of an axially displaceable piston 104 moving up and down in the combustion chamber 103 and this translatory motion of the piston 104 is transferred to a crank shaft (which is not shown) with the help of a connecting rod 105.
The inlet valve 109 and exhaust valve 112 are actuated by electronically controlled actuators (not shown). It should be noted that the inlet and exhaust valves can also be operated using mechanical actuators (not shown) but the capability of the engine will be limited when mechanical actuators are used. It should also be noted that when electronically actuated valves are used, the valve timings can be varied as needed to accommodate proper intake, scavenging and combustion.
Primary air compressor 14 (driven by an electric motor or by the engine or by a turbine) is started, which pulls in air from the air intake of the engine (not shown). An air filter 13 is placed before the compressor 14 to prevent contaminants from entering the compressor 14. The compressed air (> 15 bar, ideally > 35bar) from the compressor 14 is then transferred to the storage tank 15 (between 1-15 litres, for high-capacity engines approx. 25-35 litres). Some quantity of air is bled out, controlled by solenoid valve 22 for secondary purposes (including but not limited to actuation of pneumatic actuators). Solenoid controlled valve 16 is used to eject excess air from the system to control the pressure of air entering the intake manifold (not shown). The compressor power can also be reduced to control the pressure of air entering the intake manifold. If, the solenoid valve 16 can act as a pressure relief valve and can also intentionally prevent airflow from the air tank 15 to the intake manifold (not shown), solenoid valve 23 may be removed. Solenoid valve 23 is used to prevent compressed air from entering the intake manifold (not shown) when the engine is turned off. Solenoid valve 24 is used to prevent back flow (to the atmosphere) when the compressor is switched off.
If the engine is to run on liquid fuel only, then liquid fuel from fuel tank 1 is pumped through fuel filter 2 by fuel pump 3, to the liquid fuel injectors 108 which is a port injector and 111 which is a direct injector, injecting fuel directly into the combustion chamber 103. The fuel is injected into the inlet port 106 and/or directly into the combustion chamber 103. The quantity of fuel injected by each injector 108 and 111 can be controlled by the engine control unit (not shown) or by a separate computer (not shown). Preferably, when gasoline (or gasoline alternatives) is used as the fuel, port fuel injection may be employed, and when diesel (or diesel alternatives) is used as the fuel, direct fuel injection may be employed. During the suction stroke, the inlet valve 109 is opened and the air-fuel mixture (when port injection is employed) or compressed air (when port injection is not employed) is drawn into the combustion chamber. The inlet valve is closed and the compression stroke begins. Following the compression stroke is the power stroke. Near the end of compression stroke or near the start of power stroke, some quantity of liquid fuel may be sprayed into the combustion chamber by direct liquid fuel injector 111. During the power stroke, the charge exciter (spark plug) 114 maybe powered on in order to aid in ignition of air-fuel mixture. During the power stroke, the piston is pushed downward, and the motion is transferred to a crank shaft via a connecting rod. During the exhaust stroke, the exhaust valve 112 is opened, and exhaust fumes are transferred to exhaust treatment (not shown) through exhaust port 113 and the exhaust manifold (not shown). If the air-fuel mixture undergoes pre-ignition due to high compression ratio, the exhaust valve may be opened during the compression stroke to reduce the pressure and to prevent pre-ignition. The cycle is repeated. During operation, the air pressure, liquid fuel injection pressure (via port injector and direct injector), valve timings can be varied and optimal values for these parameters which result in proper combustion can be determined by means of trial and error. Hence, the engine reaches peak performance and/or efficiency within a few hundred combustion cycles.
If the engine is to run on gaseous fuel only, the gaseous fuel from gaseous fuel tank 7 is drawn in by the compressor 8, solenoid valve 18 is opened to allow fuel flow into the compressor 8. Solenoid valves 17 and 18 are also closed to prevent the gaseous fuel from leaving fuel tank 7 to the compressor 8 and the gaseous fuel from leaving the system, when the engine is turned off. Solenoid valve 17 is only opened while refuelling fuel tank 7. The compressed gaseous fuel from the exit of the compressor is transferred to temporary fuel tank 6 during which solenoid valve 19 is opened. Solenoid valve 19 is also capable of acting as a throttling device. The compressed gaseous fuel is then transported to vapor fuel injectors 107 which is a port fuel injector and 110 which is a direct fuel injector (injects directly into combustion chamber), through solenoid valve 25. The fuel is injected into the inlet port 106 and/or into the combustion chamber 103. The quantity of fuel injected by each injector 107 and 110 can be controlled by the engine control unit (not shown) or by a separate computer (not shown). During the suction stroke, the inlet valve 109 is opened and the air-fuel mixture (when port injection is employed) or compressed air (when port injection is not employed) is drawn into the combustion chamber. The inlet valve is closed and the compression stroke begins. Following the compression stroke is the power stroke. Near the end of compression stroke or near the start of power stroke, some quantity of vapor fuel maybe injected into the combustion chamber by direct vapor fuel injector 110. During the power stroke, the charge exciter (spark plug) 114 maybe powered on in order to aid in ignition of air-fuel mixture. During the power stroke, the piston is pushed downward, and the motion is transferred to a crank shaft via a connecting rod. During the exhaust stroke, the exhaust valve 112 is opened, and exhaust fumes are transferred to exhaust treatment (not shown) through exhaust port 113 and the exhaust manifold (not shown). If the air-fuel mixture undergoes pre-ignition due to high compression ratio, the exhaust valve may be opened during the compression stroke to reduce the pressure and to prevent pre-ignition. The cycle is repeated. During operation, the air pressure, gaseous fuel injection pressure (via port injector and direct injector), valve timings can be varied and optimal values for these parameters which result in proper combustion can be determined by means of trial and error. Hence, the engine reaches peak performance and/or efficiency within a few hundred combustion cycles. When the engine is turned off, all the compressors are switched off and all the solenoid valves are closed. The compressed fuel in storage tank 6 is throttled by solenoid valve 19 and then transported back to gaseous fuel tank 7 through now switched off compressor 8 and now opened solenoid valve 18. Solenoid valve 18 is closed to prevent leakage of gaseous fuel into compressor 8.
If the engine is to run based on multi-phase injection method, the engine is started and run as mentioned above (engine is to run on liquid fuel only). After the engine warms up (preferably to a temperature greater than the boiling point of the liquid fuel), some of the liquid fuel is pumped by fuel pump 4 through fuel filter 26 to passages 115 in the engine block, cylinder head, exhaust manifold, etc. Heat transfer occurs from the engine to the liquid fuel, and the liquid fuel evaporates to vapor state. In the figure (FIG-2) the passage (used for vaporizing liquid fuel) shown is a simple passage 115 built into the engine block. It should be noted that the passages intended for vaporizing the liquid fuel can be complex, multiple, in the cylinder block, in the exhaust manifold and tubing, etc., and they all fall under the scope of this invention. The vaporized fuel is now compressed by compressor 5 and transferred to temporary tank 6 through open solenoid valve 21. The solenoid valves 19 and 20 are closed to prevent leakage of vaporized fuel into other parts of the fluid circuit. The vaporized fuel is now transferred to vapor fuel injectors 107 which is a port fuel injector and 110 which is a direct fuel injector (injects directly into the combustion chamber), through solenoid valve 25. Now vaporized fuel has reached vapor fuel injectors 107 and 110 and liquid fuel has reached liquid fuel injectors 108 and 111. Fuel injectors 107 and 108 inject fuel into the inlet port, and injectors 108 and 111 inject fuel directly into the combustion chamber. The fuel is injected into the inlet port 106 and/or into the combustion chamber 103. The quantity of fuel injected by each injector 107,108,110, and 111 can be controlled by the engine control unit (not shown) or by a separate computer (not shown). During the suction stroke, the inlet valve 109 is opened and the air-fuel mixture (when port injection is employed) or compressed air (when port injection is not employed) is drawn into the combustion chamber. The inlet valve is closed (if the engine is to run on Atkinson cycle, the inlet valve is kept open for some part of the compression stroke) and the compression stroke begins. Following the compression stroke is the power stroke. Near the end of compression stroke or near the start of power stroke, some quantity of liquid fuel is sprayed into the combustion chamber by direct liquid fuel injector 111 and/or vaporized fuel is injected into the combustion chamber by fuel injector 110. During the power stroke, the charge exciter (spark plug) 114 is powered on in order to aid in ignition of air-fuel mixture. During the power stroke, the piston is pushed downward, and the motion is transferred to a crank shaft via a connecting rod. During the exhaust stroke, the exhaust valve 112 is opened and exhaust fumes are transferred to exhaust treatment (not shown) through exhaust port 113 and the exhaust manifold (not shown). The cycle is repeated. The preferred mode of operation is by injecting a small quantity of liquid fuel into the inlet port by liquid fuel injector 108 such that a lean air-fuel mixture is formed in the inlet port this allows the engine to work at a higher compression ratio. During the end of compression stroke and/or during the beginning of power stroke, vaporized fuel is injected into the combustion chamber by fuel injector 110. Spark plug 114 is powered in order to aid in ignition of the air-fuel mixture. Port injection of leaner air-fuel mixture allows working at a higher compression ratio. Injection of vaporized fuel directly into the combustion chamber near the end of compression stroke or near the start of power stroke allows the engine to burn more fuel at a higher compression ratio, thereby improving the power output of the engine. Another mode of operation is to completely switch to vaporized fuel injection direct injection, this allows the engine to run at higher compression ratio, thereby producing more power. During operation, the air pressure, liquid fuel injection pressure and quantity (via port injector and direct injector), vapor fuel injection pressure and quantity (via port injector and direct injector), and valve timings can be varied and optimal values for these parameters which result in proper combustion can be determined by means of trial and error. Hence, the engine reaches peak performance and/or efficiency within a few hundred combustion cycles. When the engine is switched off, all the compressors and pumps are switched off and all the solenoid valves are closed. The compressed vaporized fuel in storage tank 6 is transported to condenser 9 through now opened solenoid valve 20. The vaporized fuel condenses to liquid state in the condenser 9. The liquid fuel from the condenser is expanded through throttle valve 10 and transported to a secondary fuel tank 11. When the temperature of liquid fuel in the secondary tank 11 nears the temperature of the fuel in fuel tank 1, the fuel from secondary tank 11 is pumped to fuel tank 1.

If the engine is to run with both liquid and gaseous fuel simultaneously, sections from above literature (engine is to run on liquid fuel only, engine is to run on gaseous fuel only), can be combined. Either or both liquid fuel and gaseous fuel is injected into to inlet port and/or the combustion chamber by port injection and direct injection respectively. The working of the engine can be interpreted from the literature above. During operation, the air pressure, liquid fuel injection pressure and quantity (via port injector and direct injector), gaseous fuel injection pressure and quantity (via port injector and direct injector), and valve timings can be varied and optimal values for these parameters which result in proper combustion can be determined by means of trial and error. Hence, the engine reaches peak performance and/or efficiency within a few hundred combustion cycles. The processes which occur after turning off the engine is mentioned above (engine is to run on gaseous fuel only). As an example of operation, the engine may be started using liquid fuel and then switched to gaseous fuel employing port fuel injection by injector 107 and/or direct fuel injection by injector 110. The engine may also run by utilizing port injection of liquid fuel by fuel injector 108 such that a lean air-fuel mixture is formed in the inlet port and then injection of gaseous fuel into the combustion chamber by fuel injector 110 during the end of compression stroke and/or the beginning of power stroke.

,CLAIMS:1. A method for improving the performance of a combustion engine by utilizing multi-phase injection of fuel whereby fuel is injected as vapor, liquid, or combination, in the following steps:
i. Engine is started as a conventional engine, by utilizing liquid fuel, and is allowed to run
ii. Air is compressed using a compressor (14) and stored in a storage tank (15)
iii. If the pressure of compressed air is too high, the compressor power may be lowered and/or some air can be ejected to the atmosphere
iv. Compressed air is led into the intake manifold and is used as the fuel oxidizer
v. Fuel in liquid state is vaporized by heat exchange from the combustion engine to said liquid fuel (preferably by pumping the liquid fuel through passages (115) built in the engine).
vi. Vaporized fuel maybe compressed using a compressor (5) and then stored in a storage tank (6)
vii. Liquid fuel is injected into the inlet port such that a very lean air-fuel mixture is formed this allows the engine to work at a higher compression ratio
viii. Near the end of compression stroke or/and near the start of power stroke, the vaporized fuel is injected into the combustion chamber
ix. Spark plug or charge exciter may be powered on, to aid in ignition of air-fuel mixture, this allows for the combustion of similar or higher quantity of fuel at a higher compression ratio than a conventional engine thereby improving power output of the engine.
2. A method of improving the efficiency of a combustion engine as claimed in claim 1 wherein the fuel injected is vaporized fuel in the following steps:
i. Engine is started as a conventional engine by utilizing liquid fuel, and is allowed to run
ii. Air is compressed using a compressor (14) and stored in a storage tank (15)
iii. If the pressure of compressed air is too high, the compressor power may be lowered and/or some air can be ejected to the atmosphere
iv. Compressed air is led to the intake manifold and is used as the fuel oxidizer
v. Fuel in liquid state is vaporized by heat exchange from the combustion engine to said liquid fuel (preferably by pumping the liquid fuel through passages (115) built in the engine)
vi. Vaporized fuel maybe compressed using a compressor (5) and then stored in a storage tank (6)
vii. During suction stroke, air (or compressed air) is drawn into the combustion chamber, since only air is present, the engine can operate at a very high compression ratio
viii. Near the end of compression stroke or/and near the start of power stroke, the vaporized fuel is injected into the combustion chamber
ix. Spark plug (charge exciter) may be powered on, to aid in ignition of air-fuel mixture, this allows for the engine to run at a higher compression ratio.
3. A method of improving the efficiency of a combustion engine as claimed in claim 1 -2, wherein vaporized fuel which is at a higher temperature and pressure is transferred safely to the liquid fuel tank in the fowling steps:
i. Vaporized fuel is passed through a heat exchanger (condenser), where it condenses to liquid state
ii. Condensed fuel then undergoes expansion through an expansion valve
iii. Liquid fuel from the outlet of the expansion valve is transported to a secondary fuel tank wherein the liquid fuel is stored until its temperature reaches the ambient temperature.
iv. Fuel is now pumped back to the main fuel tank.
4. A method of improving the efficiency of a combustion engine as claimed in claim 1 -3, wherein to prevent pre-ignition of air-fuel mixture the engine is designed to work at a high compression ratio, this may cause some fuels to undergo pre-ignition during the compression stroke, to prevent this, the exhaust valve may be opened during the compression stroke to relieve some pressure, the exhaust valve is closed before the power stroke to prevent power loss.
5. A combustion engine as defined in claims 1 - 4, will have higher compression ratio, adjustable valve timings, fuel injectors for injecting vaporized fuel, fuel injectors for injecting liquid fuel and compressed air as oxidizer.
6. A combustion engine as defined in claim 5, addition of a gaseous fuel (7) tank along with a compressor (8) to compress the gaseous fuel, and a circuit to transfer the gaseous fuel to storage tank (6) will enable the engine to work with most fuels (liquid, gaseous) in a 4-stroke cycle in the following steps:
i. The liquid fuel can be injected into the inlet port and/or combustion chamber using the liquid fuel injectors.
ii. The engine may run by injection of vaporized fuel into the inlet port and/or combustion chamber.
iii. The engine may run based on methods described in claims 1-2.
iv. The gaseous fuel can be injected into the inlet port and/or combustion chamber using the vapor fuel injectors.
v. The pressure of compressed air can be adjusted to accommodate different fuels.
vi. The valve timings can be adjusted to accommodate different fuels.
vii. The spark plug may be powered on in order to aid in combustion air-fuel mixture during.