Patent Description:
With increasing environmental impact on transportation, the demand for sustainable fuels and fuel systems is increasing. The alkane gases, in particular, liquid petroleum gas (LPG) and natural gas are known as a cleaner alternative fuel for a production engine.

The engine using both diesel fuel and LPG, CNG or LNG, is referred to as gas-diesel dual fuel engine. Gas fuel in such engines is typically used as primary fuel and diesel - as secondary fuel. Gas dual fuel engines have a good thermal efficiency at high output but the performance is less during part load conditions because of poor utilization of charges. This problem is tried to be solved by several researchers. Some researchers proposed to vary such factors as pilot fuel quantity, injection timing, composition of the gaseous fuel and intake charge conditions, for improving the performance.

One of more creative approaches was adding water to internal combustion engine (Lestz SJ, et. Feasibility of cooling diesel engines by introducing water into the combustion chamber. SAE Trans <NUM>:<NUM>-<NUM>). This study showed that <NUM> lb of water injection is required per lb of fuel in order to provide removal of the waste heat, which is normally removed by jacket cooling.

Lanzafame's study (Lanzafame R. Water injection effects in a single-cylinder CFR engine. SAE <NUM>) showed that water injection in the intake pipe can be a way to avoid detonation, to reduce compression work and to control NOx production in spark ignition engines.

There is known an in-cylinder water injection engine (<CIT>) utilizing direct, in-cylinder water injection and an optional oxygen enriched air supply. According to the inventor, the in-cylinder low-temperature water injection lowers compression temperatures, which permits increased compression ratios while avoiding preignition. As well, the low-temperature water injected air/fuel increases overall engine efficiency. The known engine comprising: an internal combustion engine having at least one combustion chamber, at least one cylinder head secured to the combustion chamber and at least one piston disposed within said combustion chamber; an air/fuel intake manifold in fluid communication to the combustion chamber through the cylinder head; at least one water injector in fluid communication to the combustion chamber; a constant pressure water source connected to the water injector by a water conduit; a valve in the water conduit responsive to the compression cycle of the engine to open and let water flow to the water injector during each compression cycle of the engine; a source of enriched oxygen connected to air to the air/fuel intake manifold by an enriched air conduit; and a turbocharger compressor operatively connected to the exhaust conduit and the enriched oxygen source to compress the air passing to the enriched oxygen source.

There is known an internal combustion engine with steam expansion stroke (<CIT>), the engine having at least one cylinder, a reciprocating piston arranged in the cylinder, a combustion chamber delimited by the cylinder and the piston, and inlet and outlet valves that are controlled by a computer-based control system. The combustion engine includes elements for injecting water or water steam into the combustion chamber), and the control system is arranged to control the inlet and outlet valves and the elements for injection of water or water steam such that power strokes that are mainly based on expanding combustion gases are alternated with power strokes that are mainly based on expanding water steam.

There is known a water injection device of an internal combustion engine, and method for operating a water injection device (<CIT>). The water injection device comprising: a water tank configured to store water; a conveying element configured to convey the water, the conveying element connected to the water tank; at least one water injector configured to inject water, the at least one water injector connected to the conveying element; a pressure sensor arranged in a line region between the conveying element and the at least one water injector; and a control unit configured, based on pressure data of the pressure sensor, to determine a formation of steam in the line region when the at least one water injector is closed and the conveying element is switched off.

Another system is e.g. known from <CIT>.

The present invention is an improvement provided to solve the conversion problem of existing diesel engines to diesel and gas, such as alkane gases or mixtures thereof (e.g. LPG, CNG, LNG, bio-LPG, bio-CNG, bio-LNG) dual-fuel or only gas fuel engines and defined by independent claims <NUM> and <NUM>.

A gas ultrasonic transducer system for operating a diesel common-rail engine, comprises an electronic control unit; a water tank; a gas tank with gas supply shut-off valve; a gas level sensor; a gas pump operably connected with the gas tank; a water pump operably connected with the water tank; a mixer comprising a water level sensor and an ultrasonic transducer adapted to generate water vapor and gas mixture; wherein the mixer comprises two compartments: the upper compartment and the lower compartment, the means for separation of the upper and the lower compartments comprising an anti-reflux valve adapted to allow water vapor from the lower compartment to pass through the anti-reflux valve to the upper compartment and to prevent any liquid water from flowing into the upper compartment; wherein the upper compartment of the mixer comprises an outlet configured to be
operably connected with engine intake manifold; wherein the outlet of the gas pump is configured to be operably connected with the upper compartment of the mixer, the outlet of the water pump is configured to be operably connected with the lower compartment of the mixer, where the ultrasonic
transducer is at least partially located in the lower compartment of the mixer, i.e.below the anti-reflux valve.

The controlled interaction between elements of the system and vehicle elements results in a gas water vapor mixture. In case of embodiment with dual fuel, the water-gas mixture is calculated on the grounds of information received by the electronic control unit of the system from the engine common-rail (pressure from the rail (bar)), from the engine temperature sensor (temperature), from the air flow meter sensor (air flow - m<NUM>/s), from the acceleration pedal block (pedal position), from the lambda sensor (air-fuel equivalence ratio). In case of embodiment with gas only, the mixture is calculated on the grounds of information received by the electronic control unit of the system from the engine common-rail (pressure from the rail (bar)), from the engine temperature sensor (temperature), from the air flow meter sensor (air flow - m<NUM>/s), from the acceleration pedal block (pedal position), from the crankshaft (engine rpm).

According to one embodiment the proposed gas ultrasonic transducer system for operating a diesel common-rail engine (<FIG>), comprises: an electronic control unit <NUM>; a gas supply subsystem, comprising operably connected: a gas tank <NUM>, a gas shut-off valve <NUM>, a gas pressure regulator <NUM>, a gas pump <NUM>, a gas level sensor <NUM>; a water supply subsystem, comprising operably connected: a water tank <NUM>, a water pump <NUM>, a water level sensor <NUM>. The gas ultrasonic transducer system for operating a diesel common-rail engine further comprising a mixer <NUM> comprising the water level sensor <NUM> and an ultrasonic transducer <NUM> adapted to generate water vapor and gas mixture. The outlet of the gas pump <NUM> is operably connected with the upper compartment <NUM>' of the mixer <NUM>, the outlet of the water pump <NUM> is operably connected with lower compartment <NUM>" of the mixer <NUM>.

Thus, the mixer <NUM> (<FIG>) comprises two compartments: the upper compartment <NUM>' and the lower compartment <NUM>", the means for separation of the upper <NUM>' and the lower <NUM>" compartments comprising an anti-reflux valve <NUM> adapted to allow water vapor from the lower compartment <NUM>" to pass through the anti-reflux valve <NUM> to the upper compartment <NUM>' and to prevent liquid water from flowing into the upper compartment <NUM>'; wherein the upper compartment <NUM>' of the mixer <NUM> comprises an outlet <NUM>, which is operably connected with automobile engine intake manifold <NUM>. The ultrasonic transducer <NUM> is at least partially located in the lower compartment (<NUM>") of the mixer (<NUM>). In the air intake manifold <NUM> the gas (e.g. LPG, CNG, LNG, Bio-LPG, Bio-CNG, Bio-LNG or the like) and water vapor mixture is transported with the air to the engine combustion chamber, where the gas and water vapor mixture ignites together with the air and the diesel fuel spray.

The system further comprising an air flow meter sensor <NUM> operably connected between the mixer <NUM> outlet <NUM> and the engine intake manifold <NUM>, the air flow meter sensor <NUM> is further electrically connected with the electronic control unit <NUM> and is adapted to measure the gas mixture flow and to send respective signals to the electronic control unit <NUM> (<FIG>). Also, the system comprising a lambda sensor <NUM> operably connected with engine exhaust system; the lambda sensor <NUM> is further electrically connected with the electronic control unit <NUM> and is adapted to measure the proportion of oxygen in the gas or liquid being analyzed and to send respective signals to the electronic control unit <NUM> (<FIG>).

The electronic control unit <NUM> is electrically connected with the rail <NUM> and is designed to receive and read the common-rail pressure signal from the rail <NUM>. Also, the rail <NUM> signal may be used to control operation of the proposed system (i. entering operation mode and stand-by mode). The electronic control unit <NUM> is further electrically connected with the LPG pump <NUM> to be able to control its operation. The electronic control unit <NUM> is further electrically connected with the acceleration pedal block <NUM> to be able to receive and read a signal from the acceleration pedal block <NUM>. The electronic control unit <NUM> is further electrically connected with the engine temperature sensor <NUM> to be able to receive and read a temperature signal from the engine temperature sensor <NUM>. The electronic control unit <NUM> is further electrically connected with the automobile throttle valve <NUM> to be able to control its opening and closing. The gas (e.g. alkane gas or mixture of alkane gases) and water vapor mixture is distributed into the air intake manifold <NUM>, where the air flow is regulated by the throttle valve <NUM>.

The electronic control unit <NUM> is further electrically connected with the water level sensor <NUM> to be able to receive and read a signal from the water level sensor <NUM>. The water supply subsystem is designed to maintain the necessary water level for working of the transducer <NUM> in any conditions.

The electronic control unit <NUM> is further electrically connected with the transducer <NUM> and is designed to be able to send an output signal to the transducer <NUM>; the electronic control unit <NUM> is further electrically connected with the gas level sensor <NUM> to be able to receive and read a signal from the gas level sensor <NUM>; the electronic control unit <NUM> is further electrically connected with the gas supply shut-off valve <NUM> to be able to send output signals to control opening and closing of the shut-off valve <NUM>.

The electronic control unit <NUM> is adapted to calculate a gas and water vapor mixture composition for the mixer <NUM>, according to pre-set parameters and the information (input signals) received from the acceleration pedal block <NUM>, the rail <NUM>, the water level sensor <NUM>, the transducer <NUM>, the gas level sensor <NUM> and the air flow meter sensor <NUM>.

According to yet another embodiment the electronic control unit <NUM> is further electrically connected with the built-in car central electronic control unit <NUM>. When the rail <NUM> sends a signal (e.g. <NUM>,<NUM> V) to the electronic control unit <NUM> (used together with the e.g. 5V signal from the built-in car central electronic control unit <NUM>) - the system enters stand-by mode, while when the e.g. <NUM>,<NUM> V is received from the rail <NUM> (aprox. <NUM> bar pressure in the rail <NUM> +/- <NUM>%) the motor is running and the proposed system starts after two second delay (<FIG>). When the signal from the rail <NUM> is below e.g. <NUM>,9V, the electronic control unit <NUM> enters the proposed system to stand-by mode. According to the embodiment the rail <NUM> signal (e.g. <NUM>,<NUM> V) and built-in car central electronic control unit <NUM> signal (e.g. of 5V) is used together to enter stand-by in order to prevent system malfunctions. When one of the signals is not present, the proposed system does not start stand-by mode. For the skilled person it is obvious that the voltage level indicated above is just indicative and may have different values.

According to the preferred embodiment of the invention, the system comprises a kit, comprising: the electronic control system <NUM>; the mixer <NUM> comprising the water level sensor <NUM> and the ultrasonic transducer <NUM>; the water pump <NUM> and the gas pump <NUM> adapted to be installed on an automobile having a diesel common-rail engine. The ultrasonic transducer <NUM> is adapted to generate water vapor and gas (e.g. alkane gas) mixture; the mixer <NUM> comprises two compartments: the upper compartment <NUM>' and the lower compartment <NUM>", the means for separation of the upper <NUM>' and the lower <NUM>" compartments comprising an anti-reflux valve <NUM> adapted to allow water vapor from the lower compartment <NUM>" to pass through the anti-reflux valve <NUM> to the upper compartment <NUM>' and to prevent liquid water from flowing into the upper compartment <NUM>'; wherein the upper compartment <NUM>' of the mixer <NUM> comprises an outlet <NUM> adapted to be operably connected with an engine intake manifold <NUM>; wherein the outlet of the alkane gas pump <NUM> is adapted to be operably connected with the upper compartment <NUM>' of the mixer <NUM>, the outlet of the water pump <NUM> is adapted to be operably connected with the lower compartment <NUM>" of the mixer <NUM>, where the ultrasonic transducer <NUM> is at least partially located in the lower compartment <NUM>" of the mixer <NUM>.

According to this embodiment the water tank <NUM> is a windshield fluid tank already present in an automobile and the water level sensor <NUM> is the windshield fluid level sensor already present in the automobile's windshield fluid tank. The system can be adapted to be powered by the automobile battery. Thus, the gas pump <NUM> is adapted to be operably connected to the gas tank <NUM> already present in the vehicle. The water pump <NUM> is adapted to be operably connected to the water tank <NUM> already present in the vehicle. The electronic control unit <NUM> id adapted to be electrically connected to the following elements of the vehicle: rail <NUM>, engine temperature sensor <NUM>, acceleration pedal block <NUM>, gas level sensor <NUM>, alkane gas supply shut-off valve <NUM> and gas pressure regulator <NUM>, air flow meter sensor <NUM>, throttle valve <NUM>, vehicle battery <NUM>.

The module operates as follows. The water pump <NUM> fills the mixer <NUM>, the water level sensor <NUM> maintains the pre-set constant level of water in the lower compartment <NUM>", the ultrasonic transducer <NUM> turns on and begins to nebulize water towards the upper compartment <NUM>' of the mixer <NUM>. The anti-reflux valve <NUM> in the mixer <NUM> prevents any liquid water from flowing into the upper part of the mixer <NUM>. After receiving a signal from the car acceleration pedal block <NUM>, the electronic control unit <NUM> sends a signal to the gas pump <NUM>, which introduces the gas tangentially to the upper compartment <NUM>' of the mixer <NUM>. The mixed gas and nebulized water (water vapor) leaves from the mixer <NUM> through the outlet <NUM> to the engine intake manifold <NUM>, through the throttle valve <NUM>, being controlled by the electronic control unit <NUM>. A non-return valve <NUM> located before the water pump <NUM> ensures that the water does not return to the water tank <NUM> and the gas escapes when the gas pump <NUM> is in operation.

According to another embodiment, a diesel common-rail engine can be converted to operate only as gas (e.g. LPG, CNG, LNG, bio-LPG, bio-CNG, bio-LNG) fuel engine. According to this embodiment the system (<FIG>) further comprises a spark plug <NUM> and ignition coil <NUM> replacing the engine's glow plug. The electronic control unit <NUM> is electrically connected with the spark plug <NUM> and the ignition coil <NUM> to be able to send an output signal to the spark plug <NUM> and the ignition coil <NUM>. The electronic control unit <NUM> is further electrically connected with engine's camshaft <NUM> and engine's crankshaft <NUM> to be able to receive and read a signal from the camshaft <NUM> and the crankshaft <NUM>. Replacing the engine's glow plug by a spark plug <NUM> and the ignition coil <NUM> transforms the ignition chamber to an Otto cycle engine and the detonation is started by spark using only air and the gas and water vapor mixture instead of diesel fuel. According to the present embodiment the correct moment for ignition with spark plug <NUM> is calculated by the electronic control unit <NUM> using signal from the camshaft <NUM> and the crankshaft <NUM>, where the ignition process is equal to Otto cycle.

A method for operating a diesel common-rail engine, using the proposed gas ultrasonic transducer system comprises the following steps:.

According to one embodiment the calculation of water-vapor (WV) and gas (G) mixture at the step (iv) can be made using the following formula: WV+G, where G = ((A+B)/<NUM> - C)*D, wherein A is the common-rail pressure signal, B - acceleration pedal signal, C - air flow signal, D - lambda sensor signal and G - the effective gas (e.g. alkane gas) volume, wherein water-vapor volume is a pre-set constant value. The common-rail pressure signal, acceleration pedal signal and lambda sensor signal are calculated using the signal value in Volt. It should be noted that other ways, formulas and principles of calculation of water-vapour and gas mixture are possible.

According to yet another embodiment (<FIG>) the method further comprises the following steps before the step (i):.

According to the same embodiment the method further comprising the following step after the step (vii) of conveying the generated water vapor and gas mixture through the mixer <NUM> outlet <NUM> to the engine intake manifold <NUM>: (z) with electronic control unit <NUM> collect common rail <NUM> signal; if the signal corresponds to the set value one, return to the step (ii) of collecting acceleration pedal signal from the acceleration pedal block <NUM>; if the signal corresponds to the set value two - return to the step (c) of collecting engine electronic control unit <NUM> signal; if the signal does not correspond to the set value one and two - end process.

Claim 1:
A gas ultrasonic transducer system for operating a diesel common-rail engine, the gas ultrasonic transducer system comprising:
an electronic control unit (<NUM>); a water tank (<NUM>); a gas tank (<NUM>) with a gas supply shut-off valve (<NUM>); a gas level sensor (<NUM>); a gas pump (<NUM>) operably connected with the gas tank (<NUM>); a water pump (<NUM>) operably connected with the water tank (<NUM>); a mixer (<NUM>) comprising a water level sensor (<NUM>) and an ultrasonic transducer (<NUM>) adapted to generate water vapor and gas mixture; wherein the mixer (<NUM>) comprises two compartments: an upper compartment (<NUM>') and a lower compartment (<NUM>"); the means for separation of the upper compartment (<NUM>') and the lower compartment (<NUM>") comprising an anti-reflux valve (<NUM>) adapted to allow water vapor from the lower compartment (<NUM>") to pass through the anti-reflux valve (<NUM>) to the upper compartment (<NUM>') and to prevent liquid water from flowing into the upper compartment (<NUM>'); wherein the upper compartment (<NUM>') of the mixer (<NUM>) comprises an outlet (<NUM>) configured to be operably connected with an engine intake manifold (<NUM>); wherein the outlet of the gas pump (<NUM>) is configured to be operably connected with the upper compartment (<NUM>') of the mixer (<NUM>) and the outlet of the water pump (<NUM>) is configured to be operably connected with the lower compartment (<NUM>") of the mixer (<NUM>) where the ultrasonic transducer (<NUM>) is at least partially located in the lower compartment (<NUM>") of the mixer (<NUM>).