Patent Application
20180171890
The present invention relates to an internal combustion (IC) engine of a fumigated homogenous charge compression ignition type with a mixture of air and two different fuels inducted into a combustion chamber and compressed to combust by auto-ignition. The present invention relates particularly to a dual fumigation homogeneous charge compression ignition (DF-HCCI) engine that runs on low volatility IC engine fuel such as diesel in combination with another IC engine fuel, both fumigated in the intake air stream. More particularly, the present invention relates to a DF-HCCI engine that employs fumigation of two fuels, in which one fuel has low volatility, by a fumigation system comprising of at least one ultrasonic atomizer. Combustion phasing control is done by varying proportions of fumigated fuels, EGR rate, EGR temperature and additionally by controlling engine intake air temperature. Engine intake air is controlled to a desired temperature by a heat exchanger utilizing heat from the an engine and/or exhaust gas. A controller monitors inputs from relevant sensors and, based on these inputs, adjusts fumigation rates of fuels, EGR rates, EGR temperature and engine intake air temperature.
Homogeneous charge compression ignition (HCCI) engines have been widely studied throughout the world. In HCCI engines, HCCI combustion takes place by auto ignition of homogeneous charge and, therefore, preferably requires high cetane fuels such as diesel. However, high cetane fuels such as diesel are mostly low volatility fuels. The difficulty of low volatility fuel to vaporize and form homogeneous charge with engine intake air is one of the major challenges of HCCI engine. Difficulty in combustion phasing control at different engine operating conditions is another major problem faced by HCCI engines. Certain HCCI engines use two fuels and reactivity of charge is adjusted by varying proportions of the two fuels so as to control the combustion phasing. Such fuel reactivity control extends the range of operation for HCCI engines.
In HCCI engine, fuel reactivity control strategies with fumigation of two different fuels have been reported in the literature. However, this is generally limited to fumigations where the fuels are readily volatile or in gaseous form. Reference may be made to an article in SAE paper No. 2004-28-002, 2004 by Nagarajan et al. where they used fumigation of two volatile fuels i.e., gasoline and diethyl ether for reactivity control in HCCI engine. Reference may also be made to article in the International Journal of Automotive Technology 15(4): 517-523, 2014 by Vinayagam and Nagarajan where they used fumigation of two volatile fuels i.e., diethyl ether and ethanol in a HCCI engine using electronic fuel injectors. Reference may also be made to an article in SAE paper No. 2004-28-0020, 2004 by Nagarajan et al. where they used fumigation of two volatile fuels i.e., LPG and diethyl ether for reactivity control in HCCI engine. However, as mentioned earlier, the fumigation of two fuels for reactivity control, as reported in the literature, has been limited only to the volatile fuels. Fumigation systems used for fumigation of two fuels for HCCI combustion, as reported in the literature, are limited to be suitable only for a combination of fuels which are volatile such as gasoline, alcohol, LPG etc. The present invention overcomes this limitation and utilizes fumigation of low volatility fuel such as diesel in combination with another fuel for HCCI combustion.
Fuel reactivity control is used in certain engines by introducing two different fuels into the combustion chamber at different times to produce stratified regions that will auto-ignite under compression. Reference may be made to US patent No. US 2014/0026859 A1, 2014 by Gehrke et al. where they mentioned a Reactivity Controlled Compression Ignition (RCCI) engine with EGR which is configured to utilize a RCCI process and an EGR. The engine by Gehrke et al. is adapted to introduce two different fuels of different reactivity at different times during the intake-compression cycle of the engine. In the invention by Gehrke et al., a controller adjusts the EGR and/or the second introduction of the second fuel charge. Reference may also be made to U.S. Pat. No. 8,616,177 B2, 2013 by Reitz et al. where they use fuel reactivity stratification to control engine combustion where a lower-reactivity fuel charge is injected or otherwise introduce into the combustion chamber, preferably sufficiently early that it becomes at least substantially homogeneously dispersed within the chamber before a subsequent injection is made; one or more subsequent injections of higher-reactivity fuel charges are then made. In the above inventions by Reitz et al. (U.S. Pat. No. 8,616,177 B2) and Gehrke et al. (US 2014/0026859 A1), the fuels are injected or introduced into the combustion at different times. Further, there have been reports on vaporization of low volatility fuel using a heated chamber or hot EGR. Reference may be made to U.S. Pat. No. 6,923,167 B2, 2005 by Daniel L. Flowers where hot EGR is explained to be used for vaporization of low volatility fuel. Reference may also be made to an article in Applied Energy 99:116-125, 2012 by A. P. Singh and A. K. Agarwal where they explained the use of a heated chamber for vaporization of diesel for HCCI combustion.
Reference may be made to an article in SAE paper 910667, 1991 by Tsurutani et al. where they used an ultrasonic atomizer in SI engine for atomizing diesel at the intake of 499 cc twin cylinder 2-stroke SI outboard motor engine. In this, a wall wetting of an inlet channel was greatly reduced. With the ultrasonic atomization of diesel, it was feasible for them to run the 2-stroke SI engine with diesel fuel. Reference may also be made to an article in SAE paper 920691, 1992 by Ohkoshi et al. where they used an ultrasonic atomizer for fumigation of gasoline at the intake manifold of a commercial four cylinder diesel engine in order to achieve diesel smoke reduction. Reference may also be made to U.S. Pat. No. 6,450,154 B1, 2002 by C. Y. Choi where a piezoelectric oscillator in the combustion chamber of an HCCI engine to generate ultrasonic pressure waves to enhance fuel droplets breakup.
The main objective of the present invention is to provide a dual fumigation homogenous charge compression ignition engine (DF-HCCI) that runs on low volatility IC engine fuel such as diesel in combination with another IC engine fuel, both fumigated in engine intake air. Both fumigated fuels mix with air and they are inducted together at the same time into a combustion chamber by a suction stroke. At engine intake air stream, low volatility fuel is fumigated by ultrasonic atomizer while another fuel is injected or inducted.
Another objective of the present invention is to provide a DF-HCCI engine configured to utilize fumigation of two fuels at engine intake air stream in a way mentioned above along with exhaust gas recirculation and additionally engine intake air temperature control for combustion phasing control. Engine intake air is controlled to a desirable temperature by a heat exchanger utilizing heat from the engine and/or exhaust gas. Fuel reactivity control and thereby combustion phasing control at different engine operating conditions is done by adjusting proportions of fumigated fuels, in which one fuel has low volatility, and further by varying amount and temperature of EGR.
Still another objective of the present invention is to provide a DF-HCCI engine capable of operating over a wide range of loads and speeds.
Yet another objective of the present invention is a DF-HCCI engine configured as mentioned in the above objectives but not only limited for low volatile fuel and high volatile fuel combinations but also suitable for a combination of fuels of any volatility.
In an aspect of the present invention, the disclosure describes an internal combustion engine system utilizing a dual fumigation, an EGR and an engine intake air temperature control and an HCCI combustion process. The engine is referred here as dual fumigation homogeneous charge compression ignition engine (DF-HCCI).
In accordance with an embodiment of the present invention, the DF-HCCI engine comprises: an engine body, at least one combustion chamber in said engine body having a piston reciprocating in a cylinder, an engine intake air system to intake an air stream and deliver it to the at least one combustion chamber, an engine exhaust system to direct exhaust gases from the at least one combustion chamber, a first fuel delivery system to fumigate and supply a first fuel into the air stream, and a second fuel delivery system to fumigate and supply a second fuel into the air stream, wherein the engine intake air system is adapted to form a homogeneous mixture of the air stream, the first fuel, and the second fuel for combustion in at least one combustion chamber.
Further, in said embodiment, the first fuel delivery system comprises an ultrasonic atomizer for atomizing the first fuel having a low volatility and delivering the low volatility first fuel into said engine intake air system and the second fuel delivery system comprises an electronic injector or an ultrasonic atomizer or any fuel induction system for delivering a second fuel into said engine intake air system. Furher, the first fuel is a low volatile fuel such as diesel and the second fuel is a high volatile fuel or a gaseous fuel.
Further, in said embodiment, the first fuel and the second fuel are supplied into the air stream at the same time or at predefined timings to form the homogeneous mixture.
Further, in said embodiment, the engine intake air system comprises an intake air heating apparatus to control temperature of the air stream by utilizing heat from exhaust gas and/or the DF-HCCI engine.
Further, in said embodiment, the DF-HCCI engine further comprises an engine exhaust system to guide exhaust gases from the at least one combustion chamber.
Further, in said embodiment, the DF-HCCI engine further comprises an exhaust gas recirculation (EGR) system to recirculate a portion of engine exhaust gas. The EGR system comprises: an EGR flow control valve in communication with a flow control valve driver to regulate flow rate of the EGR into the air stream, and an EGR coolant fluid flow control valve in communication with a fluid flow control valve driver to control temperature of the EGR flowing through an EGR heating unit.
Further, in said embodiment, the DF-HCCI engine further comprises an electronic control unit to receive inputs from a plurality of sensors and transmit control signals to control fuel flow rate, EGR rate, EGR temperature, and air stream temperature. Further, in said embodiment, the DF-HCCI engine further comprises the plurality of sensors comprises one or more of temperature sensors, engine speed sensors, engine shaft crank angle sensors, and engine load sensors.
Further, in said embodiment, the DF-HCCI engine is adapted to control a combustion phase at least by varying proportions of the first fuel, the second fuel, the EGR rate, the EGR temperature, and the air stream temperature.
In accordance with another embodiment of the present invention, a method is provided to operate Dual Fumigation Homogeneous Charge Compression Ignition (DF-HCCI) Engine. The method comprising: supplying an air stream for combustion using an engine intake air system, fumigating and supplying a first fuel and a second fuel into the air stream using a first fuel delivery system and a second fuel delivery system respectively, mixing the air stream, the first fuel, and the second fuel to form a homogeneous mixture, and supplying the homogeneous mixture to at least one combustion chamber for combustion.
Further, in said embodiment, the method further comprises: controlling supply of the first fuel and the second fuel based at least on engine load and engine speed in order to achieve required combustion timing in a combustion phase, controlling an EGR rate and an EGR temperature based at least on the engine load and the engine speed, and heating the air stream to a required temperature using an intake air heating apparatus.
In another aspect, the disclosure describes a DF-HCCI engine with combustion phasing control done by a combined strategy of varying proportions of the two fumigated fuels and varying the EGR rate and the EGR temperature and additionally by controlling the engine intake air temperature. Fumigation of two fuels, in which one fuel has low volatility, is performed by a dual fuel fumigation system of the present invention that comprises at least one ultrasonic atomizer. Further, the scope of the invention is not intended to be limited to the particular forms disclosed. The invention covers all equivalents, modifications, and alternatives falling within the scope and spirit of the invention as defined by the claims.
It is difficult to use low volatility fuel such as diesel for homogeneous charge compression ignition mode of combustion, given the difficulty to vaporize such fuel. It is also difficult to control combustion phasing in homogeneous charge compression ignition mode of combustion. The engine of the present invention uses low volatility fuel such as diesel in combination with another fuel for homogeneous charge compression ignition mode of combustion. Fumigation of two fuels, in which one fuel has low volatility, is performed by a dual fuel fumigation system comprising of at least one ultrasonic atomizer. Combustion phasing control is done by a combined approach which varies proportions of two simultaneously fumigated fuels, EGR rate, and EGR temperature and additionally controls engine intake air temperature. Such combined approach of combustion phasing control using the ultrasonic atomizer and where one fuel is a low volatility fuel is not known by prior arts or by literature.
The present invention relates to an internal combustion engine of a fumigated homogenous charge compression ignition type that operates on two fuels, in which one fuel has low volatility. Both fuels are fumigated simultaneously in the engine intake air stream by a novel dual fuel fumigation system comprising of at least one ultrasonic atomizer. The DF-HCCI engine overcomes the difficulty faced by HCCI mode of combustion to utilize fumigation of low volatility fuel such as diesel in dual fuel mode along with other fuel. Low volatility fuels in the context of the present invention refer to those liquid fuels which are not readily vaporized by fuel injector equivalent to low pressure gasoline fuel electronic injector typically used in present day vehicles. The dual fuel fumigation system comprises a pair of fuel delivery systems, for example, first fuel delivery system and second fuel delivery system. One of the fuel delivery systems has an ultrasonic atomizer and the other fuel delivery system has an electronic injector or ultrasonic atomizer or any suitable fuel induction system. Both the fuels are simultaneously fumigated into the engine intake air stream or engine intake air. Both fumigated fuels mix with the engine intake air and they are inducted together, at the same time, into engine combustion chamber where homogeneous charge compression ignition takes place. Said dual fuel fumigation system uses a pair of ultrasonic atomizer systems for fumigation of both fuels, continuous dual fuel fumigation strategy is used. In the continuous dual fuel fumigation strategy, both fuels are continuously fumigated by the ultrasonic atomizer systems. Said dual fuel fumigation system uses ultrasonic atomizer system for fumigation of low volatility fuel and electronic liquid or gaseous fuel injector system for fumigation of the other fuel, timed dual fuel fumigation strategy is used. In the timed dual fuel fumigation strategy, low volatility fuel is continuously fumigated by the ultrasonic atomizer system and the other fuel is injected at suitable timing by the electronic injector system such that best possible mixing of both fuels with intake air is achieved. The meaning of simultaneous fumigation of two fuels, in the context of the present invention, covers such timed dual fuel fumigation strategy also. Further, in the context of the present invention, the meaning of both fuels mixing with intake air and getting inducted together at the same time also covers induction of fuels and air mixture to combustion chamber resulting from such timed dual fuel fumigation strategy. In the DF-HCCI engine of the present invention, combustion phasing control is done by varying proportions of fumigated fuels, EGR rate, and EGR temperature and additionally by controlling engine intake air temperature. The engine intake air is controlled to a desirable temperature by a heat exchanger utilizing heat from the engine and/or engine exhaust gas. A controller monitors inputs from relevant sensors and, based on these inputs, adjusts fuels fumigation rates, EGR rates, EGR temperature and also the intake air temperature. The engine intake air stream or engine intake air can be used interchangeably.
The DF-HCCI engine system includes an engine body with a combustion chamber. The combustion chamber has a piston reciprocating in a cylinder for the different strokes associated with the HCCI mode of combustion. The engine system in accordance with the present invention includes a dual fuel fumigation system comprising of at least one ultrasonic atomizer for fumigation of two fuels, in which one fuel has low volatility. Both fumigated fuels mix with engine intake air and they are inducted together, at the same time, into engine combustion chamber where homogeneous charge compression ignition combustion takes place. The engine system further includes an intake manifold and an exhaust manifold to direct engine intake air to the combustion chamber and to direct the combustion products out from the combustion chamber respectively. The engine system also includes an engine intake air heating and control system utilizing heat from the engine and/or engine exhaust gas. The engine system further includes an exhaust gas recirculation (EGR) system which recirculates a portion of the engine exhaust gas to the engine intake air with a control system to control the temperature and the amount of the EGR. The engine also includes sensors monitoring engine operating parameters and multiple temperature signals and a controller controlling fuelling rates, EGR rate and temperature and intake air temperature.
In the present invention, the fumigation of low volatility fuel by ultrasonic atomizer and the fumigation of another fuel by injection or induction or ultrasonic atomizer would be utilized in a DF-HCCI engine so that diesel or any other low volatility fuel can be fumigated with another fuel and the mixture of air and the two fuels inducted together at the same time into the combustion chamber for HCCI combustion. The fuel reactivity control and thereby the combustion phasing control at different engine operating conditions is done by adjusting the proportions of fumigated fuels and further by varying the amount and temperature of EGR. Intake air is also controlled to a desirable temperature through a heat exchanger utilizing heat from the engine and/or exhaust gas.
The DF-HCCI engine of the present invention is configured to induct two fuels together at the same time into the combustion chamber by the suction stroke, one of the fuels being a low volatility fuel such as diesel. As mentioned earlier, low volatility fuel such as diesel is difficult to fumigate in the engine intake air stream. Diesel can be atomized to very fine particles by the ultrasonic atomizer. More particularly, the fumigation of diesel or other low volatility fuel by the ultrasonic atomizer and the fumigation of another fuel by injection or induction or any suitable technique both at the intake air stream, so that the mixture of air and the two fuels are inducted together at the same time into the combustion chamber by the suction stroke for HCCI combustion and further with control of EGR rate and temperature and also control of intake air temperature, has not been reported so far.
The present invention differs from the known solutions in that, in the DF-HCCI engine, fuels of two different reactivity's, of which one fuel has low volatility, are not injected at different times but they are fumigated and inducted together at the same time into the combustion chamber by the suction stroke for HCCI combustion. Further, the DF-HCCI engine is configured to utilize low volatility fuel such as diesel in combination with another fuel.
The fumigation of diesel by ultrasonic atomizer along with fumigation of another fuel by injection or induction at the intake air stream so that both fuels and air mixture is inducted together at the same time into the combustion chamber of an HCCI engine is not disclosed by known arts. Particularly, a combustion phasing control in HCCI using fuel reactivity control by fumigation of two fuels which comprise of (i) diesel or other low volatility fuel fumigation by ultrasonic atomizer and (ii) fumigation of another fuel by injection or induction or any suitable technique so that mixture of air and both fuels is inducted together at the same time into the combustion chamber of the DF-HCCI engine is not disclosed by known arts.
The present invention ensures that an ultrasonic atomizer has been used for fumigation of low volatility fuel at intake air stream in HCCI engine and, particularly, in the configuration and method of the present invention.
The present invention ensures simultaneous dual fuel fumigation with at least one ultrasonic fuel atomizer for fumigating two fuels, in which one fuel has low volatility, for HCCI combustion. Further, in the present invention, HCCI combustion phasing control is performed by a combined strategy of varying fumigation rates of two fuels, in which one fuel has low volatility, by dual fuel fumigation system having at least one ultrasonic atomizer and varying EGR rate and EGR temperature.
In accordance with an embodiment of the present invention,
In the illustrated embodiment, fuel storage systems 44 and 60 are used to store fuels for the DF-HCCI engine 10. The fuel supply systems 46 and 62 pump fuels and/or regulate the pressure of fuels. Valves 48 and 64 shut off or open to control delivery of fuels for engine combustion. Flow control valves 50 and 66 along with flow valve drivers 52 and 68, as shown in
The illustrated embodiment also includes an electronic control unit (ECU) 98 which receives inputs from sensors such as those of temperature, engine speed, crank angle and sensors related to engine load, as shown in
In the embodiment of the present invention shown in
In the embodiment of the present invention shown in
Depending on temperatures of the engine intake air and the engine operating parameters such as load and speed, the ECU 98 provides control signals for fuel flow rates of two fuels to get suitable fuel reactivity while at the same time it also provides control signals for controlling EGR rate and EGR temperature and the engine intake air temperature control. The ECU 98 may also utilize other sensors inputs which additionally provide information to better compute control signals. For example, when intake air temperature is low and engine is operating at specific speed and load, the ECU 98 is configured to control auto-ignition ignition timing by providing control signals corresponding to specific flow rates of two fuels and also provide control signal corresponding to specific EGR temperature and EGR flow rate and the engine intake air temperature. Therefore, the combustion phasing control is achieved by controlling parameters such as the fuel reactivity, EGR flow rate, EGR temperature and engine intake air temperature. Further, it should be noted that fuel reactivity control can be done for the combination of the fuel with low volatility such as diesel with another fuel of any volatility or combination of any two fuels of any volatility.
The illustrated embodiment as shown in
The present DF-HCCI engine may be used for any stationary or non-stationary applications such as power generation, agriculture, and automotive engines. The definition of fuel in the DF-HCCI engine is not restricted to only fuels but it also encompasses chemicals or any such compound, used in any suitable quantity, which can be used for combustion or which can affect combustion. The DF-HCCI engine operates in dual fuel mode, however, at some operating points of the engine, only one fuel may be used for combustion. In the present invention, the combustion phasing control is done by varying proportions of the fumigated fuels, EGR rate and EGR temperature and additionally by varying engine intake air temperature. Of the four parameters, i.e., varying proportions of the fumigated fuels, varying EGR rate, varying EGR temperature and varying engine intake air temperature, any one of them or combination of them or all of them can be employed depending on engine requirements.
The following example is given by way of illustration of the present invention and should not be construed to limit the scope of the present invention. Following is a brief summary of the exemplary version of the invention.
In the exemplary DF-HCCI engine of the present invention, hot water from the engine body 120 has two outlets. A first hot water outlet 980 is for circulating water to the intake air heating system 30 and a second hot water outlet 1000 is for circulating hot water to an engine radiator system for cooling of the hot water. The engine radiator system is a heat exchanger system for cooling engine coolant comprising components and accessories such as a thermostat, valve, hose pipes, fan controlled by electronic controlled unit, heat exchanger etc., integrated together in a manner well known in the art of internal combustion engine design and vehicle design. For the sake of simplifying the illustrated drawings, the engine radiator system is not shown in the present embodiment. A hot engine coolant circulation both through the intake air heating system 300 and the radiator system is accomplished by an engine coolant pump 380. An engine coolant from a radiator is circulated through inlet 1020 by the engine coolant pump 380. In the exemplary DF-HCCI engine, an exhaust gas recirculation (EGR) system 800 recirculates a portion of an engine exhaust gas. An EGR flow control valve 820 and a flow control valve driver 840 regulate a flow rate of the EGR into the engine intake air. In the present exemplary DF-HCCI engine, an EGR temperature is controlled by a fan 880 which blows air to the EGR heat exchanger 860. The ECU 960 controls operation of a fan 882 through a fan driver 900 so as to get the desired EGR temperature downstream of the heat exchanger 860. Temperature sensors 920 and 940 are positioned to measure the EGR temperature upstream and downstream of the heat exchanger 860.
In the exemplary engine of the present invention, the liquefied petroleum gas (LPG) is stored and supplied from a fuel cylinder 600. Solenoid valves 620 and 640 control the opening and closing of a fuel supply. The Liquefied petroleum gas is vaporized at a vaporizer 660. The pressure of gas downstream of the vaporizer 660 is reduced by a pressure reducer 680 and the gas is finally injected by an electronic injector 700. An additional solenoid shut-off valve, not shown in the illustrated drawing, may also be used before the electronic injector 700. A gas injection duration per combustion cycle and a gas injection timing are provided by the ECU 960 to the injector driver 720. Another fuel tank 440 is provided that stores and supplies fuel of low volatility, which is diesel in the exemplary DF-HCCI engine of the present invention. The diesel supply is done by a fuel pump 460. A diesel flow control valve 500 controls flow rate of diesel to ultrasonic atomizer system 540. The ultrasonic atomizer system is explained in more detail elsewhere in this document. A fuel shut-off valve 480 stops fuel supply to the ultrasonic atomizer system 540 when the engine is not running. A fuel return line 580 feeds back excess diesel to an inlet line of the fuel pump 460. Diesel flow rate control signals at given load and speed are provided by the ECU 960 to a flow control valve driver 520. The LPG and diesel are fumigated into air-fuel mixing chambers 560 and 740 at an engine intake manifold where air-fuel mixing takes place. Depending on the temperature of the engine intake air and the engine operating parameters such as load and speed, the ECU 960 provides control signals to the ultrasonic atomizer system 540 and the electronic injector driver 720 so that the suitable diesel and LPG flow rates are maintained to achieve desired fuel reactivity while at the same time the ECU 960 also provides control signals for controlling EGR rate and EGR temperature and engine intake air temperature control. Combustion phasing control is achieved by varying proportions of fumigated fuels, the EGR rate, and the EGR temperature and additionally by controlling the engine intake air temperature.
The main advantages of the present invention are:
The present invention can utilize low volatile fuel such as diesel in combination with another fuel for HCCI mode of combustion. Low volatile fuels are difficult to atomize and vaporize to form a homogeneous charge with engine intake air.
The present invention can use a combination of any two fuels, such as low volatile fuel with another fuel, which may be volatile fuel or which may be gaseous fuel, for homogeneous charge compression ignition mode of combustion. Combustion phasing control in homogeneous charge compression ignition mode of combustion is done by varying ratio of two such fuels and by varying EGR rate and EGR temperature and additionally by controlling engine intake air temperature.
| Number | Date | Country | Kind |
|---|---|---|---|
| 201611043424 | Dec 2016 | IN | national |
