Abstract:
A dual fuel system for a vehicle utilizing gasoline and propane fuel sources. The dual fuel system includes a micro-controlled switch box that switches back and forth between fuels. A fuel injector rail and fuel injectors are also included that can function to inject either gasoline or propane. A display and selector switch are also provided inside the cabin of the vehicle to allow the user to read system information and manually select a type of fuel.

Description:
FIELD OF THE INVENTION 
       [0001]    The present invention generally relates to fuel systems for an internal combustion engine. More particularly, the present invention relates to a dual fuel system for an internal combustion engine that utilizes both gasoline and propane. 
       BACKGROUND OF THE INVENTION 
       [0002]    It is estimated that there are currently 300 million vehicles on America&#39;s roads. Every day, the average American spends almost an hour driving in a car. Additionally, approximately 70% of goods that are shipped in America travel on commercial vehicles. Clearly, automobiles are an integral part of everyday life in America. The same is true for most countries around the world. 
         [0003]    The world&#39;s dependence on automobiles creates a similar dependence on fuel sources to power those automobiles. Most vehicles on the roads today are fueled by gasoline or diesel fuel. Our need for these fossil fuels, however, creates a host of problems. First (and most notably) is cost. Rising prices at the gas pump is a frequent source of concern and contention in America. Gasoline and diesel prices seem to fluctuate on a daily basis, but there is a definite upward trend in fuel pricing. A decade ago, gas prices averaged about $1 per gallon in the United States. Today, the average price per gallon in America is close to $4. And there are no indicators to suggest that gas prices will go down in the foreseeable future. 
         [0004]    Another problem our need for fossil fuels gives rise to is pollution. According to the United States Environmental Protection Agency (EPA), an average car produces over 600 pounds of air pollution every day. These air pollutants include: carbon monoxide, nitrogen dioxide, particulate matter, ozone, sulfur dioxide, and lead. All these pollutants are known sources of a wide variety of health problems in humans, as well as ozone depletion and acid rain in the environment. Many speculate that air pollution is also causing the gradual and irreversible warming of the globe. Transportation sources now account for 77% of national total carbon monoxide emissions. Approximately 3.8 grams of volatile organic compounds (another harmful source of pollution) are emitted by every car every day, even when the car is not driven. 
         [0005]    Increases in vehicular pollution have in turn given rise to numerous governmental attempts at regulating the source of the pollution. One of the most notable of these attempts is called “The Clean Air Act”. The Clean Air Act was passed by Congress in 1970, and most recently amended in 1990. This act sets air quality standards for emissions from area, stationary, and mobile sources. It states that the EPA is authorized to set National Ambient Air Quality Standards which protect human health and the environment. The Air Quality Standards set by the EPA are monitored across the country and enforced via testing, reporting, fines, and even law suits. Individual states also have their own environmental protection regulations and methods of enforcement. 
         [0006]    California&#39;s Air Resources Board (CARB) is the strictest regulatory body concerned with pollution in the country. The emissions standards set by CARB are stricter than the federal EPA requirements; specifically with regards to hydrocarbon and nitrogen oxide emissions—which become smog. Older vehicles in California are required to be retrofitted so that they operate cleaner. The gasoline sold in California is also required to have less sulfur, benzene and hydrocarbons than most gasoline sold elsewhere in the United States. CARB also oversees an emissions rating program for cars that are driven and sold in California. Cars can be rated: Low Emission Vehicle (LEV), Ultra Low Emission Vehicle (ULEV), Super Ultra Low Emission Vehicle (SULEV), Partial Zero Emission Vehicle (PZEV), or Zero Emission Vehicle (ZEV). Since 2004, CARB has mandated that every new car sold in California must be a LEV or better. Currently, 16 other states have adopted, or are in the process of adopting, California&#39;s strict emissions standards. 
         [0007]    Accordingly, there is a need for a fuel system that can provide a low-cost alternative to standard fuel prices that creates less pollution and meets various emissions standards. The present invention fulfills these needs and provides other related advantages. 
       SUMMARY OF THE INVENTION 
       [0008]    The present invention is directed to a dual fuel system for an internal combustion engine. The system includes a first fuel tank and a second fuel tank. The first fuel tank is in fluid communication with a first fuel inlet on a fuel switch. The second fuel tank is in fluid communication with a second fuel inlet on the same fuel switch. The second fuel inlet is separate and distinct from the first fuel inlet. A fuel outlet on the fuel switch is in fluid communication with a combustion chamber on the engine. The fuel switch is configured to switch between a first state of connecting the first fuel inlet to the fuel outlet and a second state of connecting the second fuel inlet to the fuel outlet. 
         [0009]    The system further includes a microcontroller in the fuel switch. A microcontroller is configured to control the fuel switch and selectively switch between the first state and the second state. The control of the fuel switch by the microcontroller is preferably responsive to data received from an engine sensor. The engine sensor may be configured to measure RPMs, temperature, first fuel level, second fuel level, mileage, or duration of engine operating states. The control of the fuel switch by the microcontroller may also be responsive to a selector switch movable between a first position corresponding to the first state and a second position corresponding to the second state. 
         [0010]    The system may further include a fuel injector rail disposed between and in fluid communication with both the fuel outlet of the fuel switch and the combustion chamber. A fuel injector may be included on the fuel injector rail so as to be in fluid communication with the combustion chamber. In addition, a plurality of fuel injectors may be included on the fuel injector rail, with each of the plurality of fuel injectors being in fluid communication with one of a plurality of combustion chambers in the engine. The fuel injector and fuel injector rail are preferably configured to operate at ignition temperatures of about nine hundred twenty degrees to one thousand twenty degrees Fahrenheit. 
         [0011]    The first fuel tank preferably contains gasoline and the second fuel tank preferably contains propane. The fuel switch may comprise a rotating switch having a central aperture configured to fluidly connect one of the first fuel inlet or the second fuel inlet to the fuel outlet. The rotating switch preferably seals off the second fuel inlet when the central aperture fluidly connects the first fuel inlet to the fuel outlet. Conversely, the rotating switch seals off the first fuel inlet when the central aperture fluidly connects the second fuel inlet to the fuel outlet. 
         [0012]    Other features and advantages of the present invention will become apparent from the following more detailed description, taken in conjunction with the accompanying drawings, which illustrate, by way of example, the principles of the invention. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0013]    The accompanying drawings illustrate the invention. In such drawings: 
           [0014]      FIG. 1  is a plan view of an automobile, illustrating a car engine utilizing the dual fuel system of the present invention; 
           [0015]      FIG. 2  is a side cut-away view of a car engine, illustrating a fuel injector connected to the dual fuel system of the present invention; 
           [0016]      FIG. 3  is a schematic of the dual fuel system, illustrating the flow path of the two types of fuel; 
           [0017]      FIG. 4  is an enlarged cut-away view of the switch box of the dual fuel system, illustrating the rotating switch and microcontroller; and 
           [0018]      FIG. 5  is an environmental view of the dashboard of a car, illustrating the display and selector switch for the dual fuel system of the present invention. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0019]    The present invention is a dual fuel system for a fuel injected internal combustion engine. In the preferred embodiment, the dual fuel system of the present invention includes a standard gasoline tank, a propane tank, a switch box with a microcontroller, fuel injector rails with fuel injectors, a dashboard display and controller, as well as all the necessary hoses and connectors. The dual fuel system utilizing gasoline and propane responds to the needs described above in several respects. Propane is a widely available, inexpensive fuel source that burns cleanly and efficiently in a car. Few alterations are needed for a standard fuel injected engine to be able to run on propane. Also, the dual fuel system of the present invention enables an automobile user to meet stringent emissions requirements and regulations with a minimum level of inconvenience and expense. The dual fuel system will generally be referred to herein by the numeral  10 . 
         [0020]    The dual fuel system  10  of the present invention is shown in  FIG. 1 . Here, a car  12  is shown with an engine  14 , a fuel injector rail  24 , and four fuel injectors  26 . A gasoline tank  16  and a propane tank  18  are connected with hoses  28  to a switch box  20 . The switch box  20  also houses a microcontroller  22 . The switch box  20  is connected to the fuel injector rail  24  with a hose  28 . 
         [0021]    Fuel injection systems replaced the old carburetor systems. Carburetors supplied fuel to the engine based on suction while fuel injection systems supply fuel via a direct injection spray. The amount of fuel sprayed into engine&#39;s combustion chamber corresponds to the amount of air entering the engine. This means that the fuel injection system makes the engine much more efficient. 
         [0022]    Normally, a fuel injection system only functions with one type of fuel. The dual fuel system  10  of the present invention functions with both standard gasoline and liquid propane. The dual fuel system  10  can be retrofitted into an existing car, or it can be factory installed into a new car. The dual fuel system  10  requires both the standard gas tank  16  as well as a separate propane tank  18 . The propane tank  18  may be made of carbon fiber, or some other material that is puncture resistant and capable of transporting materials under pressure. In a retrofit, the propane tank  18  may be mounted inside the trunk of the vehicle where the dual fuel system  10  is being used. Alternately, the propane tank  18  may also be mounted on the undercarriage of the car  12 , or any other place where the propane tank  18  will fit without compromising the safety and functionality of the car  12 . 
         [0023]    Propane is a by-product of natural gas processing and petroleum refining. It is most commonly used as fuel for barbecues, portable stoves, and residential central heating. 90% of propane used in the United States is produced in the United States. It also has a relatively high octane rating at  110 . This means that propane is relatively clean burning and very stable. Liquid propane gas has a higher ignition temperature of 920-1020 degrees; versus 80-300 degrees for gasoline. It also will only burn with an air-fuel ratio of between 2.2% and 9.6% and will rapidly dissipate beyond its flammability range in the open atmosphere, making it very safe compared to gasoline. Propane is typically less expensive than gasoline and widely available (although not through typical gas stations). Because propane is released as a gas, it does not spill, pool or leave a residue. Also, propane contains almost no carbon. Carbon in gasoline is what turns engine oil black. That means that using propane as a fuel source will vastly prolong the life of a car&#39;s engine oil. All-in-all, propane is a very desirable fuel source for use in both personal and commercial vehicles. 
         [0024]    A standard gasoline engine can burn propane with very few alterations. The only changes that need to be made are to the fuel injector rail and the fuel injectors. The existing fuel injector rail and fuel injectors must be removed and replaced with the fuel injector rail  24  and fuel injectors  26  of the present invention. These components are configured to handle the range of pressures and temperatures necessary to accommodate both gasoline and propane. The placement of the fuel injector  24  in the engine  14  of a car  12  is illustrated in  FIG. 2 . Here, a standard engine  14  is illustrated. Air is received through the intake manifold  30  into the combustion chamber  38  as the intake camshaft  42  is drawn up. This creates the vacuum necessary to draw the air in. When the intake camshaft  42  is pushed back down, fuel is injected into the combustion chamber  38  by the fuel injector  48 . The fuel injector  48  basically acts as an atomizer, producing a fine spray of fuel that is easily ignited by the spark plug  40 . Once the spark plug  40  ignites the fuel, the resulting combustion forces the piston  32  down into the crankcase  34 , which in turn rotates the crankshaft (not shown). At this point, the exhaust camshaft  44  draws back to create the vacuum necessary to drive the exhaust out of the combustion chamber  38  through the exhaust manifold  46 . 
         [0025]    The fuel injector  48  is supplied by the fuel supply line  50 . The fuel supply line  50  is, in turn, connected to the switch box  20 . The switch box  20  serves to switch back and forth between gasoline and propane. Thus, the switch box  20  has two input supply lines: the gas supply line  52  and the propane supply line  54 . The switch box  20  is controlled by a microcontroller  22  housed therein. The microcontroller  22  has a logic circuit (not shown) and receives data inputs from various engine sensors (i.e. RPMs, temperature, etc). The microcontroller  22  causes the fuel that is run through the fuel supply line  50  to switch back and forth between gasoline and propane based on these data inputs. Alternately, the driver of the vehicle may manually switch the fuel source from a switch on the dashboard inside the car (described below). The switch box  20  receives gasoline from the gasoline supply line  52 , and propane from the propane supply line  54 . 
         [0026]    The dual fuel system  10  is illustrated schematically in  FIG. 3 . Here the gasoline tank  16  and the propane tank  18  are shown connected to the switch box  20  via the gasoline supply line  52  and the propane supply line  54 . As described above, the fuel supply line  50  connects the switch box  20  to the fuel injectors  26  via the fuel injector rail  24 . The fuel injector rail  24  is basically a pipe with a series of apertures  56 . Each aperture  56  is fitted with a fuel injector  26 . The seat between each fuel injector  26  and aperture  56  is sealed such that no leaks occur, even at high temperatures and under high pressure. The fuel injector rail  24  serves to deliver fuel to each fuel injector  26  at a consistent pressure so that fuel can be evenly distributed by all fuel injectors  26 . The fuel injectors  26  are controlled by an electronic control unit (ECU)  58 . The ECU  58  tells the fuel injectors  26  when to inject fuel and how much fuel to inject. The ECU  58  is typically part of the car&#39;s computer control system (not shown). 
         [0027]    The switchbox  20  is shown in a cut-away side view in  FIG. 4 . Here, the functionality rotating switch  64  is illustrated. The rotating switch  64  is configured to allow only one type of fuel through to the fuel supply line  50  at a time. The dual fuel system  10  does not mix different fuel types to create a blended fuel. Rather, only one fuel source is burned at a time. The rotating fuel switch  64  ensures that only one type of fuel runs through the switch box  20  at a time. It does this by providing a central aperture  66  that allows for only one type of fuel to pass through the rotating switch  64  at a time. When the rotating switch  64  is positioned such that the central aperture  66  is aligned with the propane supply line  54 , the gasoline supply line  52  is completely blocked. Likewise, when the rotating switch  64  is positioned such that the central aperture  66  is aligned with the gasoline supply line  52 , the propane supply line  54  is completely blocked. When the central aperture  66  is aligned with either the propane supply line  54  or the gasoline supply line  52 , it is also aligned with the fuel supply line  50  at the other end of the switch box  20 . In this way, only one type of fuel passes through the switch box  20  at a time. 
         [0028]    The rotating switch  66  is controlled by the microcontroller  22 . The microcontroller  22  has a series of sensor inputs  60 . These sensor inputs  60  carry data from various engine sensors (not shown) and provide the microcontroller  22  with information about the operating environment inside the engine. The microcontroller  22  is connected to the rotating switch  64  via a microcontroller connection  62 . In other embodiments of the dual fuel system, the switch box  20  may have a different mechanism other than the rotating switch  64 . Regardless of mechanism used, the switch box  20  in any embodiment of the present invention will allow only one type of fuel to pass through at a time. 
         [0029]    The microcontroller  22  can be programmed to control the rotating switch  64  so as to maximize the efficiency of the dual fuel system. The microcontroller  22  can be programmed based on time, temperature, or volume. For example, if a driver knows that he will be driving all day, the microcontroller  22  can be programmed to switch from gasoline to propane at a certain time (when the driver knows he will be traveling through an area with more stringent emissions requirements). Likewise, the microcontroller  22  can be programmed to switch from gasoline to propane when the engine temperature reaches a certain point because propane is more stable than gasoline at higher temperatures. The microcontroller  22  can also be programmed to automatically switch to propane when the gas tank  16  is running low, and vice versa. In other embodiments of the dual fuel system  10 , the microcontroller  22  can be programmed to switch between fuel sources based on other factors such as RPMs, mileage, geographic location, etc. In this way, the dual fuel system  10  can automatically optimize fuel usage in any type of vehicle. The microcontroller  22  may also be programmed with fail safe procedures in the event of a leak or loss of pressure in the fuel system. In the event that something goes wrong in the fuel system, the microcontroller  22  simply reverts the fuel system back to OEM standards. 
         [0030]    The dual fuel system  10  may also be manually controlled. In  FIG. 5 , the steering wheel  68  and dashboard  70  of a car are illustrated. Typically, the dashboard  70  is home to air conditioning vents  72  and the radio display and controls  74 . The dual fuel system  10  also includes a system display  76  and selector switch  78  that are installed on the dashboard  70  of a car. The system display  76  for the dual fuel system  10  may display such information as: engine conditions, current fuel source, fuel volume (for both propane and gasoline), automatic settings, etc. The selector switch  78  enables the driver to override the automatic programming of the microcontroller  22  (see  FIG. 4 ) and switch fuel sources on the fly. This functionality is useful if the vehicle is being driven from one region with relaxed emissions regulations into another region with more stringent emissions regulations. 
         [0031]    Although several embodiments have been described in detail for purposes of illustration, various modifications may be made to each without departing from the scope and spirit of the invention. Accordingly, the invention is not to be limited, except as by the appended claims.