Background of the Invention This invention relates to engines, and more particularly to an improved engine system employing a vaporized fuel delivery system.

Heretofore, typical engine fuel delivery systems have supplied liquid fuel and system/ambient temperature to either fuel injection systems or, with older vehicles, to naturally aspirated carburetion. However, the internal combustion engine employing such fuel delivery has major drawbacks pertaining to air quality standards and fuel economy. The millions of vehicles producing exhaust emissions affect worldwide populations with changes to weather patterns. Also, people are developing new health reactions due to dangerous levels of these exhaust emissions.

Further, poor air quality is responsible for the deterioration of natural products such as rubber, buildings, statues and the like. Dangerously high levels of ground level ozone are present in many areas, while upper atmosphere ozone layers are being depleted, fueling concerns about ultraviolet rays from the sun. Furthermore, global oil reserves are being rapidly exhausted, and the invention will significantly extend the lifetime of those resources.

These prior systems use liquid fuel delivered to an internal combustion engine. The fuel is sprayed as a liquid mist in to an intake manifold. As the fuel is atomized, upon entry to the intake manifold, it is hoped that the mist will eventually be converted to a vapor when exposed to a partial vacuum within the intake manifold on its way to the combustion chamber. The partial vacuum naturally lowers the boiling point of the liquid fuel. Prior attempts have been made to produce a 100% vaporized fuel, delivered separately to each cylinder of an engine.

However, heretofore, these systems have not been completely successful.

Summary of the Invention In accordance with the invention, an improved fuel delivery system employs pre-vaporization of a fuel. In alternative embodiments, the fuel is heated and vaporized by RF inductive heating, resistive heating, or a combination of both. The vaporized fuel is provided to the engine intake or to the cylinders. In a significant aspect of the invention, the vaporized fuel is provided on demand and without significant delay.

Accordingly, it is an object of the present invention to provide an improved engine with reduced fuel consumption and operating costs.

It is yet another object of the present invention to provide an improved engine fuel delivery system that results in a significant reduction of exhaust emissions.

It is a further object of the present invention to provide a clean air solution for diesel, gasoline, and other fossil-fueled powered engines.

Yet another object of the invention is to provide an improved engine system with lower buildup of carbon and other foreign matter in the engine.

A further object of the present invention is to provide an improved engine with significant extension of vehicle maintenance cycle.

The subject matter of the present invention is particularly pointed out and distinctly claimed in the concluding portion of this specification. However, both the organization and method of operation, together with further advantages and objects thereof, may best be understood by reference to the following description taken in connection with accompanying drawings wherein like reference characters refer to like elements.

Brief Description of the Drawings FIG. 1 is a block diagram of the overall engine fuel delivery system according to the present invention.

FIG. 2 is a side sectional view of a fuel vaporizer according to the invention.

FIG. 3 is an end view of the fuel vaporizer of FIG. 2, tal<en in the direction of arrow 3 in FIG. 2.

FIG. 4 is a component arrangement in block diagram form of a second preferred embodiment of the invention.

FIG. 4A is a perspective view of a first embodiment of a vaporizer according to the invention.

FIG. 4B is a side elevational view of a second embodiment of a vaporizer according to the invention.

FIG. 4C is a right end elevational view of the embodiment shown in FIG. 4B.

FIG. 4D is a left end elevational view of the embodiment shown in FIG. 4B.

FIGS. 5 through 10 illustrate alternative configurations of exemplary vaporizers.

FIGS. 11-19 are alternative views of vaporizers employing internal baffle members within the internal chambers of the vaporizers.

FIG. 20 is a schematic illustration of the control module according to one embodiment of the invention.

FIG. 21 is a block diagram of the control module startup protocol.

FIG. 22 is a block diagram of the control module heater control protocol.

FIG. 23 is a block diagram of the control module injector control protocol.

Detailed Description Turning now to the drawings, the invention will be described with reference to preferred embodiments of the invention. The system according to a first preferred embodiment of the present invention includes an RF magnetic induction heated vaporizer that converts fuel to a vapor, and might include a supplemental resistance heater. The vaporized fuel is then introduced into the intake manifold of the engine or to the cylinders by fuel injection methods. The system is sealed, whereby any fuel vapor not consumed by the engine is recycled and collected for future use.

Referring to FIG. 1, a block diagram of the overall engine fuel delivery system according to the first preferred embodiment, a fuel tank 10 stores the particular fuel, which may be gasoline or diesel, or the like. A fuel pump 12 draws fuel from the tank, supplying it to a liquid fuel control valve 14 (LFCV). LFCV 14 serves to supply fuel to the injector 16 responsive to the fuel demand of the engine, and to return excess fuel to fuel tank 10 for re-use. The injector 16 supplies fuel into a vaporizer 18, which is provided with heaters 20 for heating and vaporizing the liquid fuel as discussed hereinbelow. Vaporized fuel from the vaporizer is directed through pressure regulator 22 to a safety valve 24. The safety valve is in-line and serves as a one-way check valve for fuel vapor flowing to injector 26, which is shown as a single injector, but in practice could include multiple injectors. Injector 26 injects the vaporized fuel into an intake manifold 28, thereby providing fuel to the engine.

Injector 26 is also in fluid communication with a condenser 30 (as is also the pressure regulator 22), the condenser being further connected to the fuel tank 10. A fuel enrichment injector (FEI) injector 34 is also in fluid communication with the intake manifold, and receives fuel input from the fuel pump 12. An electronic processor 36 is provided for control, receiving input from sensors 35 monitoring the operation of the system and controlling the operation via output actuators 37.

In operation, fuel from the tank 10 is drawn out by the fuel pump, passing through the liquid fuel control valve to injector 16. The injector supplies the fuel into the vaporizer 18, which is heated to a sufficient temperature by heaters 20 to cause the liquid fuel to convert to a vaporized state, in most cases between 138 and 500 degrees F. Of course, the specific temperature can be modified depending on the type of fuel in use for maximum vapor production. The vaporized fuel flows through the pressure regulator 22 and safety valve 24, into injector 26, which supplies the vaporized fuel to the intake manifold of the engine, under injection timing control of the electronic processor 36. Excess fuel not used by the injector at a given moment is returned to the fuel tank via condenser 30, which converts the fuel vapor back to a liquid state. The pressure regulator also returns any excess fuel to the fuel tank via condenser 30. The fuel enrichment injector 34 provides additional fuel (in a partially vaporized, or vaporized form) directly to the engine in response to a sudden load demand on the engine. Also, the FEI provides fuel during initial cold starts by use of a liquid fuel injector. Note that the FEI may comprise a single injector, injecting fuel at a position of delivery where fuel is admitted into the fuel induction unit of the engine.

Referring now to FIG. 2 and FIG. 3, which are a side sectional and an end view respectively of a fuel vaporizer, the vaporizer comprises a cylindrical stainless steel vessel (preferably formed from 400 series stainless steel) having a hollow interior that is substantially sealed to the exterior. The vessel could be made in other shapes and from any other suitable material without departing from the scope of the invention. A fuel inlet 42 is provided in the chamber end wall at one end of the vaporizer, and spaced in from the edge of the cylinder about 1/4 the diameter of the cylinder body. Near the opposite side of the cylinder, a fuel vapor outlet 44 is provided, again about 1/4 the body diameter from the edge of the cylinder. The invention is not intended to be limited to any specific location on the chamber. Two sensor/gauge ports 43 are provided and communicate with the inside of the vaporizer body to monitor inlet and outlet temperatures. At the end of the body distal from the sensor/gauge ports, a drain outlet 45 is provided, centrally located in the end wall.

An RF magnetic inductive heater 46 surrounds the vaporizer body. The RF magnetic inductive heater comprises a RF source coupling its energy to the vaporizer unit by means of an inductor. For example, the vaporizer unit is positioned within the turns of a coil that is coupled to receive the output of the RF source. In FIG. 2 and FIG. 3, the RF magnetic inductive heater 46 is illustrated schematically, but includes one or more coil members surrounding the body of the vaporizer. In a particular embodiment, a coil having two primary windings is employed. To enable access to the sensor/gauge ports 43, the RF magnetic inductive heater 46 is provided with openings, or is shaped to not cover the area of the ports 43.

In operation, fuel injected into the vaporizer is electronically regulated based on fuel demands. The RF magnetic inductive heater is driven to heat the vaporizer and/or the vaporizer outlet, whereupon liquid fuel injected by injector 16 (FIG. 1) into the vaporizer is vaporized. The liquid fuel can if necessary, be preheated prior to injection into the vaporizer. In one such embodiment, the preheating is achieved by heater in communication with the fuel delivery line. The vaporized fuel is then supplied to operate the engine. In this preferred embodiment, the RF magnetic inductive heater is operated at a frequency of between 26 and 85 kHz, with one kilowatt of power. The specific frequency and power levels might vary with different applications, and can be readily determined by one of skill in the art.

Preferred dimensions for the vaporizer chamber 40 are between 5 and 12 inches in length, outer diameter of between 1 and 6 inches, with a wall thickness ranging from 0.065 to 0.25 inches. The end walls of the cylinder are also between 0.065 and 0.25 inches thick and the inlet 42 and outlet 44 are 1/4 the diameter of the cylinder from the outer circumference of the end wall. The sensor/gauge ports 43 are 1 inch from the end of the cylinder, or, alternatively, 1/6t'the overall length of the cylinder from the end wall, each comprising 0.25 inch tapped openings. Outlet 45 is a 0.125 inch tapped opening. FIG. 3 is a transparent end view of the fuel vaporizer of FIG. 2, taken in the direction of arrow 3 in FIG. 2. The placement of inlet 42, outlet 44 and sensor/gauge ports 43 are also shown in this view.

In an alternative embodiment, the vaporizer is provided as a two-stage device, wherein a first stage employs a resistive heating element to pre-heat the fuel to a temperature above the ambient temperature. Then, the second stage, comprising the RF magnetic inductive heated vaporizer, is employed for final vaporization of the fuel. The first stage may comprise a reservoir of pre-heated fuel to be drawn upon as needed, or a pre-heated fuel delivery line as discussed above.

Referring now to FIGS. 4-22, another preferred embodiment of the invention will be described. Referring first to FIG. 4, a flow diagram schematic is used to illustrate liquid fuel flow as it is brought to the vaporizer. Fuel pump 50 draws liquid fuel from fuel tank 49. Fuel pump 50 pumps the liquid fuel through a bypass check valve 52 to the vaporizer inlet valve 54. Excess fuel, i. e. fuel in excess of that required by the engine, is bypassed through fuel return line 51 to the fuel tank 50.

Bypass check valve 52 also prevents back flow of liquid fuel from the vaporizer to the fuel tank 49 through either the fuel pump 50 or fuel return line 51. The vaporizer inlet valve 54 admits liquid fuel into the vaporizer 58 responsive to the fuel load demand of the engine. Vaporizer 58, which is illustrated schematically in Fig.'s. 4 and 4A, may be one of several designs, examples of which will be described in greater detail below with reference to FIGS. 5-19. Vaporizer inlet valve 54 is electrically controlled to open for a predetermined time period to supply necessary liquid fuel into the vaporizer responsive to system fuel demands. The electrical control is achieved by the transmission of an electrical pulse sent to the vaporizer inlet valve 54 from control module 79. In general, sensors collect engine management data that are provided as input signals to the control module 79, which processes the input signals and produces output signals to control the vaporizer inlet valve 54, which may comprise, for example, a fuel injector as previously stated. As shown in FIG. 4A, release or purge valve 68 may be incorporated as part of the vaporizer vessel for returning unused liquid fuel to a purge tank 70, or directly to the fuel tank 49. A pressure sensor 60, located at the vaporizer outlet port, and temperature sensor 62, measure the pressure and temperature inside the vaporizer.

Two temperature sensors may be provided for redundancy and averaging of measured temperature variables. The temperature and pressure sensors generate output signals 64,66 to the control module 79, which controls heating elements that heat and vaporize the fuel in the vaporizer. In the embodiment shown in Fig.'s 4B, 4C and 4D, the vaporizer body 410 includes a central vaporizer channel 412.

Surrounding channel 412 are four-heater cavities 414a-d. In each of the four heater cavities is a resistive heating element. Each heating element comprises a cartridge resistance heater which in one embodiment has the following specifications: 3%- 7% wattage variance; 45 maximum amps; 15 volts maximum voltage. The wall 416 between the central chamber and the heater cavities is thin, preferably about 1/8 inch, to facilitate ready heat transfer between the heaters and the central chamber through which the fuel flows.

In certain embodiments, a second resistive heat source in the form of heat tape is used to preheat fuel prior to its introduction into the vaporizer. Flexible tape heaters are of low wattage, typically 150 watts or less, and operate on a maximum voltage of 15 volts.

Vaporized fuel is discharged from the vaporizer by outlet valve 72 responsive to control signals received from the control module 79. The vaporized fuel then flows through safety valve 74 and into the engine induction system 75. Safety valve 74 is prevents the back flow of vapor into the vaporizer 58. Excess vapor pressure in the vaporizer output piping between the vaporizer 58 and the engine induction system 75 is relieved through a vapor pressure control valve 76 to a condenser 78.

Condensed fuel is then returned to the fuel tank 49.

In one preferred embodiment, a flow through induction fuel heater 79 is inserted between the vaporizer outlet valve 72 and the safety valve 74. The RF induction heater 77 is a cylindrical chamber having an inside diameter of one half inch and a length of four inches. Applicant has found that an RF induction heater of these dimensions is well suited to a broad range of engine sizes and applications, although the invention is not intended to be limited to any specific dimensions. In general, Rf induction heater 77 uses radio frequency (RF) radiation to inductively heat the chamber walls and in turn the fuel contained therein. A complimentary push-pull parallel MOSFET half bridge power driver is excited to26 kHz and used to drive a series electrical connection of the work coil and a parallel capacitor bank.

The 12VDC auto battery serves as the power source through 4 feet of 9 AWG (American Wire Gauge) coil wire. The results of inputted energy include a 70 volts p-p AC voltage across the work coil implying approximately 45 amps rms (root mean square) used to generate the eddy currents in the vapor chamber wall. In one instance, the time to heat the RF induction heater 77 from ambient temperature to 135 degrees F. was approximately 30 seconds. Control of power inputted to heat vapor in the RF heating unit is based on periods of resonance and non-resonance to effectively and instantaneously turn the RF heating unit 79"on"and"off". The resonance is affected by periodically adjusting the power driver frequency to 26 kHz, which in the case of one preferred embodiment, represents the required resonant frequency. In one preferred method of operation, the gasoline vapor leaves vaporizer 58 and enters RF induction heater 77 at approximately 138 °F, where it is further heated to about 180-200° F. In another aspect of the operation of the invention, the volumes and power of the vaporizer 58 and the RF induction heater 77 are sufficient meet the full load demands of the engine referred to herein as"on demand", and further to transition rapidly from partial power to full power, thereby eliminating the need for storage of vaporized fuel in amounts beyond that necessary to meet a brief low-load to full-load transient in the engine operation.

FIG. 5 through FIG. 10 represent illustrations of specific configurations of exemplary vaporizers. FIG. 5 is a cylindrical pre-pressurized vaporizer 80, comprising a pre-pressurized lower chamber 82, a piston member 84, having seals so as to define and separate the lower chamber from an upper chamber 86. A stop rod 88 is provided to define the maximum upward movement limit of the piston.

The upper chamber is heated, for example by heating elements 90. Liquid fuel is injected at valve 54', and the pressure/temperature are measured by transducers 60' and 62'. Output fuel vapor exits via valve 72'. A fill valve/pressure relief valve 92 is provided to the lower chamber 82.

In operation, the pressure in the vaporizer chamber 82 can be changed (via adding or removing air, for example, through valve 92) to adjust the upper chamber pressure, keeping the upper chamber relatively constant. Alternatively, the piston may be biased by use of a spring or the like, to keep the upper chamber pressure higher than it would otherwise be. FIG. 6 illustrates a double-chamber cylindrical vaporizer 94. Vaporizer 94 employs heating elements 96 positioned between inner and outer chamber walls. In this configuration, there is no direct contact with the heating coils and the vapor.

FIG. 7 and FIG. 8 are front and side views of a rectangular vaporizer body 98, adapted for use when spatial considerations do not allow use of a cylindrical vaporizer body. Heating is by any suitable means, such as resistance heating or RF heating.

Figs. 9 and 10 are perspective views of a cylindrical vaporizer 58 and a rectangular vaporizer 98, respectively. Inlet and outlet ports, transducer ports and fill/pressure relief valve ports are also visible.

In certain cases, the vaporizers may be provided with internal baffles. Internal baffles are provided to create more uniform heating surfaces, to increase the surface area of the vaporizer and to cause turbulence within the vaporizer. FIGS. 11-13 illustrate suitable baffle members. The configurations of FIGS. 11-13 are shown adapted for use in a cylindrical vaporizer body. However, it will be understood that corresponding baffle members may be employed in other vaporizer configurations.

In FIG. 11, a baffle plate 100 has plural dimples defined therein. The dimples pass through the plane of the plate, defining small protrusions or bumps 102 on one face of the plate. FIG. 12 shows plate 104, with plural holes therein. While the holes are uniform in size in the illustrated embodiment, varied size and spacing is employed.

FIG. 13 illustrates baffle member 106, comprising a screen having openings of 1/8"" inch or less. Each of the baffle members is preferably constructed from stainless steel, although this is not a requirement.

Referring to Figs. 14-19, exemplary placement of baffles is shown. Vaporizer 110 (FIG. 14) has plural baffle members 108 positioned therein, five baffles being used in the illustrated embodiment. In FIG. 15, a baffle 114 aligned along the longitudinal (or vertical) axis of a cylindrical vaporizer 112 is illustrated. Figs. 16 and 17 are front and side views respectively of a rectangular vaporizer body 114 employing horizontally aligned baffle members 116 (five such baffles being illustrated). Figs. 18 and 19 are front and side views respectively of a rectangular vaporizer body 118 with a vertically aligned baffle member 120 therein. The vertical baffle extends approximately 3/the length of the internal cavity of the vaporizer.

Turning now to FIG. 20, the control system will be described in greater detail.

The control board consists of a combination of programmable logic devices and microcontrollers. The control system monitors various sensors to gather environmental and engine operating data. Sensors include, but are not limited to, manifold absolute pressure (MAP), vaporizer temperature, intake air temperature, transfer tube temperature, throttle position, factory injector pulse-width and park/neutral safety switch status. Sensor data is then combined with known engine parameters such as volumetric efficiency and displacement to determine the fuel demands of the engine under changing environmental and load conditions.

The control module receives input from multiple sensors and generates output signals to control the operation of the injectors that admit liquid fuel into the vaporizer and the heaters that heat and vaporize the fuel on demand. In some embodiments, the sensors interact with the full application of the on-board programming language to meet the drivability requirements of the vehicle during periods of engine idle, no-load engine acceleration, loaded engine acceleration, vehicle deceleration, downshift acceleration, steady speed operation, and during sustained load or passing. Sensor 62 (FIG. 4A) is a temperature sensor is mounted to the vaporizer body. The temperature sensor circuit is designed as a voltage divider to be used to vary the voltage through the A-D converter to the module. The function of the temperature controls is based on circuit design using differences in circuit resistance as monitored by a thermistor.

Sensor MAP (manifold absolute pressure) is used to monitor engine manifold vacuum. Engine manifold vacuum is a reliable indicator of engine load conditions using inches of mercury for the unit measurement value. In preferred embodiments of the invention, there is an inverse relationship between MAP values and injector pulse width, which is varied by the control module 79 to match engine fuel demands. As the engine is called upon to deliver more power, there is also a need to deliver more fuel. As the demand for additional fuel is signaled by a drop in the manifold pressure, the control module signals an increased pulse width for the injector, thereby increasing fuel delivery. In preferred embodiments, pulse width signals representing injector flow durations of between about 0.05 and 31.5 milliseconds are generated using software and DIP switch settings. This range of operation represents a full scale duty cycle between 0 to 100 percent for most passenger and commercial vehicle operations. If needed for a specific application, pulse widths representing any desired injector flow duration can be achieved.

Sensor TPS (throttle position switch) is an electro-mechanical sensor used to measure distance traveled by throttle linkage movement. The position and movement of the throttle is thus measured as an indicator of the required fuel load, and is utilized by the control module as one input used to determine the optimal injector pulse width.

Sensor RPM (revolutions per minute) measures the rotational speed of the engine in revolutions per minute, and is used as a measure of fuel demand. As a further level of electronically monitoring, a circuit designed to process a"table look-up value" will be electronically addressed to prescribed values of overall engine fuel demands.

Sensor OS relays elemental oxygen content values from the engine exhaust as a measure of the air to fuel ratio in the engine, i. e.,"rich"or"lean"conditions. Sensor OS is a galvanic battery that generates voltage values between 0-1 volt as the percentage of oxygen in the exhaust varies from 0 to 100%. Voltage levels are received by the control module, which in response assigns specified output signals to control the injector pulse width. Sensor T2 measures the temperature of the fuel vapor leaving vaporizer 58 through the outlet port of the vaporizer. This temperature value, in conjunction with fuel demand and desired fuel vapor final temperature, is used to control the RF heating coil in the RF induction heater.

The operation of the system will now be described in greater detail with reference to FIGS. 4 and 21-23. Referring to FIG. 4, when the ignition is activated, typically by turning the key to its"ON"position, fuel is admitted to the vaporizer through injector 54. The heating elements of vaporizer 58 are energized to heat and vaporize the fuel in the vaporizer to a desired operational temperature, typically 138 -500° F. FIG. 21 is a block diagram of the control module control of the heater circuits, enrichment injector and injector circuits during start up. FIG. 22 is a more detailed block diagram of the heater control protocol employed by the control module during start up. In general, the control module activates or deactivates one or more of the available heaters in response to the temperature detected in the vaporizer. As heat is applied to the vaporizer, fuel within the vaporizer begins to vaporize. Expanded fuel generates pressure within the vaporizer. A minimum pressure level of 10 PSI must be obtained before the vehicle is started. Once the vaporizer reaches its prescribed temperature and pressure, an enrichment injector is activated to inject fuel into the engine to assist in starting. The operator is then signaled to activate the engine's starter. Once the control module detects that the engine starter is engaged, the injector control protocol is initiated. The default value for the injector operation is that of no-load idling, which is signaled until the engine is started. In another embodiment, the engine can be started using the FEI.

Once the engine is running, the injector control protocol illustrated in FIG. 23 is initiated. The control module receives the values for manifold pressure, exhaust 02, RPM, and the throttle position from the respective sensors. The control module then references a preprogrammed lookup table to determine appropriate enrichment factors for the particular combination of measured values detected, and generates a pulse width output signal to the primary injector that in turn admits a predetermined amount of fuel into the vaporizer. The temperature and pressure conditions in the vaporizer and RF inductive heater are simultaneously monitored by the control module to provide the required heat input to continuously vaporize the required amount of fuel.

In the event that the control module detects a transient fuel demand that cannot be met by the primary injector, additional fuel enrichment capability is achieved using a third in-line injector positioned after the vaporized fuel leaves both the vaporizer and RF heating unit.

Applicant has found that the invention as described herein provides significant improvements in fuel economy and emissions control over prior art systems. While the invention has been described with reference to the foregoing preferred embodiments, those skilled in the art will recognize that numerous changes in detail and arrangement may be possible without departing from the scope of the following claims.