Abstract:
A portable on-demand hydrogen supplemental system is provided for producing hydrogen gas and injecting the hydrogen gas into the air intake of internal combustion engines. Hydrogen and oxygen is produced by a fuel cell from nonelectrolyte water in a nonelectrolyte water tank. The hydrogen gas is passed through a hydrogen gas collector. Nonelectrolyte water mixed with the hydrogen gas in the hydrogen gas collector is passed back thru the tank for distribution and water preservation. The system can be powered by the vehicles alternator, a stand-alone battery, waste heat or solar energy. The system utilizes an an onboard diagnostic (OBD) interface in communication with the vehicle&#39;s OBD terminal, to regulate power to the system so that hydrogen production for the engine only occurs when the engine is running. The hydrogen gas is produced it is immediately consumed by the engine. No hydrogen is stored on, in or around the vehicle.

Description:
CROSS-REFERENCES 
       [0001]    This is a continuation-in-part application of U.S. application Ser. No. 13/224,338, filed Sep. 2, 2011 which is a continuation-in-part application of U.S. application Ser. No. 12/790,398, filed May 28, 2010, the contents of which are incorporated herein by reference. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    The present invention relates to hydrogen generation devices. More particularly, the present invention relates to a hydrogen supplemental system that can be used with internal combustion engines for increased fuel efficiency and reduced carbon emissions. 
         [0004]    2. Description of the Related Art 
         [0005]    There are a number of devices on the market that create HHO gas, otherwise known as Brown&#39;s gas, which is used as a supplement to gasoline and diesel engines. HHO gas consists of two parts hydrogen to one part oxygen. These devices typically comprise an electrolyzer which decomposes water into hydrogen and oxygen. An example is U.S. Pat. No. 3,368,696. These electrolyzers typically use an electrolyte, most notably KOH, Potassium hydroxide, or baking soda. A voltage is placed across the device to produce the HHO gas. 
         [0006]    The main problem with most of these devices is that the energy required to produce the hydrogen creates a substantial load on the electrical system of the vehicle. Similar to running the air conditioner in any vehicle, the additional electrical load causes the miles per gallons to be reduced. Even though the hydrogen typically boosts the efficiency and miles per gallon of the vehicle, the additional electrical load on the vehicle to create the hydrogen is usually great enough to minimize or in many cases negate most or all of mileage gains of the vehicle. 
         [0007]    Also, most HHO systems produce the hydrogen and oxygen in a combined gas stream. The hydrogen and oxygen gases are not generally separated from each other. In the case of modern gasoline powered vehicles, this extra oxygen is detected by the vehicle&#39;s oxygen sensors which communicate this extra oxygen level to an on-board computer, namely and Electronic Control Unit ECU of the vehicle. When the ECU detects this extra oxygen, it is a signal that the engine is running lean and the ECU adds more gasoline to the engine. This also negates most of the fuel efficiency gains. 
         [0008]    Furthermore, HHO systems generally use either baking soda or Potassium Hydroxide KOH. KOH is generally preferred over baking soda because of its stability and because it causes less deterioration of stainless steel plates or other plates used in the electrolyzer. However, KOH has to be handled with care because it is caustic, and the crystals can be dangerous if not handled properly. The electrolyte normally has to be inserted into the unit at the proper proportions for optimum operation of the electrolyzer. Extreme care must be taken when using it. It is not the type of product you would generally like to put in the hands of an inexperienced consumer. 
         [0009]    Complex installation is another issue with typical HHO systems. Space usually has to be found somewhere in the engine compartment or outside the vehicle. Since all vehicles are different, finding a suitable spot under the hood to install the device in many vehicles is next to impossible. Also, the systems are typically connected into the electrical systems of the vehicles which can cause blown fuses and a host of other problems if not installed properly. Hydrogen is only needed when the vehicle is actually running, not when the ignition is turned on. During the installation, care must be observed to make sure the electrical power is provided to the device only when the engine is running. Otherwise there can be hydrogen accumulation in the air intake. This further complicates the installation of these systems. 
       SUMMARY OF THE INVENTION 
       [0010]    The present invention relates to a portable and compact, on-demand hydrogen supplemental system for producing hydrogen gas and injecting the hydrogen gas into the air intake of internal combustion engines, particularly for vehicles. Hydrogen and oxygen is produced by a fuel cell at low temperatures and pressure from nonelectrolyte water in a nonelectrolyte water tank. The hydrogen gas is passed through a hydrogen gas collector. Nonelectrolyte water mixed with the hydrogen gas in the hydrogen gas collector is passed back thru the nonelectrolyte water tank for distribution and water preservation. The hydrogen gas and the oxygen gas travel in separate directions, therefore the gases are kept separate. In the case of gasoline engines, the hydrogen gas is directed to the air intake of the engine while the oxygen gas is optionally vented to the atmosphere. The system can be powered by the vehicles alternator, a stand alone battery, waste heat or solar energy. The system utilizes an engine sensor or an onboard diagnostic (OBD) interface in communication with the vehicle&#39;s OBD terminal, to regulate power to the system and therefore hydrogen production for the engine only occurs when the engine is running. Therefore as the hydrogen gas is produced it is immediately consumed by the engine. No hydrogen is stored on, in or around the vehicle. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0011]    The foregoing and a better understanding of the present invention will become apparent from the following detailed description of example embodiments and the claims when read in connection with the accompanying drawings, all forming a part of the disclosure of this invention. While the foregoing and following written and illustrated disclosure focuses on disclosing example embodiments of the invention, it should be clearly understood that the same is by way of illustration and example only and the invention is not limited thereto, wherein in the following brief description of the drawings: 
           [0012]      FIG. 1  is a detailed drawing of a front view of a portable hydrogen supplemental system showing a water tank and other components of an interior housing design according to the present invention. 
           [0013]      FIG. 2  is a detailed drawing of a left side view of the portable hydrogen supplemental system according to the present invention. 
           [0014]      FIG. 3  is a detailed drawing of a right side view of the portable hydrogen supplemental system according to the present invention. 
           [0015]      FIG. 4  is a detailed drawing of a rear view of the portable hydrogen supplemental system according to the present invention. 
           [0016]      FIG. 5  is a diagram illustrating the operation and details of a PEM electrolyzer according to the present invention. 
           [0017]      FIGS. 6A-B  are diagrams of an embodiment of the hydrogen gas collector  20  according to the present invention. 
           [0018]      FIGS. 7A-B  are diagrams of an embodiment of the cup portion receiving the water container according to the present invention. 
           [0019]      FIG. 8  is a schematic showing a portable hydrogen supplemental system installed in a typical vehicle according to the present invention. 
           [0020]      FIG. 9  is a diagram of an embodiment of a sub-housing assembly according to the present invention. 
           [0021]      FIG. 10  is a diagram of an embodiment of a control circuit of the present invention. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0022]    The present invention as will be described in greater detail below provides an apparatus, method and system, particularly, for example, a hydrogen supplemental system used to increase the fuel efficiency and reduce carbon emissions for internal combustion engines. The present invention provides various embodiments as described below. However it should be noted that the present invention is not limited to the embodiments described herein, but could extend to other embodiments as would be known or as would become known to those skilled in the art. 
         [0023]    Various components of a portable hydrogen supplemental system  1  are discussed below with reference to  FIGS. 1 through 4 . The present invention as shown in  FIG. 1  provides the portable hydrogen supplemental system  1  which includes a housing unit  2  that can be secured in the trunk or other flat surface of a vehicle by mounting bracket  3  and fastening units  4 . Inside the housing unit  2  are a fuel cell  5  and a nonelectrolyte water tank  6  positioned above the fuel cell  5 . A cup portion  7  is disposed above the nonelectrolyte water tank  6  and is configured to receive a water container  8  therein for supplying nonelectrolyte water  9  to the nonelectrolyte water tank  6 . The nonelectrolyte water tank  6  is arranged above the fuel cell  5 , in such a manner as to supply nonelectrolyte water  8  to the fuel cell  5  by gravity. The nonelectrolyte water tank  6  is supported in the housing unit  2  above the fuel cell  5  by supporting means (not shown). The housing unit  2  is designed to be readily removable from the mounting bracket  3 . 
         [0024]    The nonelectrolyte water tank  6  includes a fill spout  10  at a top portion thereof for receiving the cup portion  7 , a water supply fitting  11  (as shown in  FIG. 2 ) positioned on a rear side thereof connected to a tube or other supply means  12  that is in turn connected to water inlet fittings  13   a  and  13   b  on the fuel cell  5  by first and second manifolds  14   a  and  14   b . Nonelectrolyte water  9  is supplied to the fuel cell  5  by the supply means  12 . The fuel cell  5  also includes hydrogen gas outlet fittings  15  connected via a third manifold  16  (as depicted in  FIG. 3 ) and tubes or additional supply means  17  and a fitting  18 , to a hydrogen gas collector  20  (as depicted in  FIG. 4 ) mounted to a rear of the cup portion  7  via a gas inlet fittings  21 . 
         [0025]    The nonelectrolyte water tank  6  further includes a sensor port  25  (as shown in  FIG. 2 ) for receiving a water level sensor. The water level sensor is configured to sense a water level of the nonelectrolyte water tank  6 . A temperature sensor may also be provided. The temperature sensor may be mounted within the nonelectrolyte water tank  6  or any suitable location within the housing  2  and is configured to sense a temperature of the nonelectrolyte water  9 . A heater may further be provided along a surface of the electrolyzer  5 , mounted to a sub-housing assembly or any suitable location within the housing  2 , and configured to heat the nonelectrolyte water  9  when it is detected via the temperature sensor that the nonelectrolyte water  9  has dropped below a predetermined temperature (e.g., 32 degrees). The nonelectrolyte water tank  6  also includes tank vent port  27  for releasing air trapped within the nonelectrolyte water tank  6  via a tube or other supply means  28  connected via a fitting  29 , to an outlet  30  formed within the cup portion  7 . 
         [0026]    The cup portion  7  further includes a plurality of flange portions including a first flange portion  31  disposed in a horizontal direction parallel to a top portion of the nonelectrolyte water tank  6 , and a second flange portion  32  disposed in a vertical direction and connected with or integrally combined with a rear or back side of the first flange portion  31 . The cup portion  7  further includes a container receiving portion  34  for receiving the water container  8  therein. The cup portion  7  is mounted above the nonelectrolyte water tank  6  via supporting structures  35  or other supporting means. 
         [0027]    A main power board  36  is disposed at a rear side, for example, of the system  1  and configured to supply power to the system  1  using power received via power terminals  37  and  38  (as depicted in  FIG. 3 ). A connector  36   a  is provided for connecting an OBD interface of the system  1  thereto. Further, power terminals  37  and  38  are connected to a vehicle battery for supplying power to the system  1 . A heat sink  39  is also provided on the main power board  36  for dissipating heat and cooling components of the main power board  36 . 
         [0028]    Referring back to  FIG. 1 , the fuel cell  5 , which is commonly known to produce electricity, is operated in reverse to produce hydrogen and oxygen gases. Thus, the fuel cell  5  essentially operates as an electrolyzer, which as described above decomposes nonelectrolyte water  9  into hydrogen gas and oxygen gas and is hereinafter referred to as an electrolyzer  5 . Nonelectrolyte water  9  fills the electrolyzer  5  from the nonelectrolyte water tank  6  and when a voltage, having positive and negative terminals, is placed across the electrolyzer  5  supplied from the main power board  36 , hydrogen and oxygen gases  22  and  23  are produced, on opposing sides of the electrolyzer  5 . 
         [0029]    During operation of the electrolyzer  5 , the oxygen gas bubbles  22  are generated in the fuel cell  5  and released from one of the water inlet fittings  13   a  and  13   b  which also functions as an oxygen gas outlet fitting, back through the supply means  12  and is vented out of a rear side of the system  1  via the supply means  12 . Further, hydrogen gas  23  is generated in the fuel cell  5  and supplied to the hydrogen gas collector  20 . A small amount of non-electrolyte water  9  will exit from the hydrogen gas outlet fitting  15  as the hydrogen gas is produced. The hydrogen gas collector  20  is configured to collect the hydrogen gas  23  and the nonelectrolyte water output from the fuel cell  5 . Since the oxygen gas bubbles  22  are released back through the supply means  12 , any nonelectrolyte water  9  in contact with the oxygen gas bubbles  22  remains within the supply means  12  for supplying to the electrolyzer  5 . Any nonelectrolyte water  9  exiting from the hydrogen gas outlet fitting  15  with the hydrogen gas  23  is collected in the hydrogen collector  20  is returned to the nonelectrolyte water tank  6  via a water return port  24  of the tank  6 , for returning the nonelectrolyte water  9  by a tube or other supply means  25  to the nonelectrolyte water tank  6  via the water return port  24 , for water preservation. The nonelectrolyte water  9  that comes out of the hydrogen outlet fitting  15  and the water inlet fittings  13  and  13   a  during hydrogen and oxygen production is therefore maintained in the nonelectrolyte water tank  6 . Additional details regarding the hydrogen gas collector  20  will be discussed below with reference to  FIGS. 6A and 6B . Based on the configuration of the system  1 , the hydrogen gas and the oxygen gas generated in the electrolyzer  5  travel in different directions and are therefore kept separate from each other. 
         [0030]    According to the invention the electrolyzer  5  can, for example, be a proton exchange membrane or polymer electrolyte membrane (PEM) electrolyzer. A PEM electrolyzer includes a semipermeable membrane generally made from ionomers and designed to conduct protons while being impermeable to gases such as oxygen or hydrogen. This is their essential function when incorporated into a membrane electrode assembly (MEA) of a proton exchange membrane fuel cell or of a proton exchange membrane electrolyzer: separation of reactants and transport of protons. 
         [0031]    As known an electrolyzer is a device that generates hydrogen and oxygen from water through the application of electricity and includes a series of plates through which water flows while low voltage direct current is applied. Electrolyzers split the water into hydrogen and oxygen gases by the passage of electricity, normally by breaking down compounds into elements or simpler products. 
         [0032]    A PEM electrolyzer is shown in  FIG. 5 . The PEM electrolyzer includes a plurality of layers which are non-liquid layers including at least two external layers and an internal layer, including external electrodes  41  disposed opposite to each other one of which is the anode  41   a  and the other of which is the cathode  41   b , electrocatalysts  42   a  and  42   b  disposed respectively on the anode  41   a  and the cathode  41   b , and a membrane  43  disposed between the electrocatalysts  42   a  and  42   b . The PEM electrolyzer further includes an external circuit  44  which applies electrical power to the anode  41   a  and the cathode  41   b  in a manner such that electrical power in the form of electrons flow from the anode  41   a , along the external circuit  44 , to the cathode  41   b  and protons are caused to flow through the membrane  43  from the anode  41   a  to the cathode  41   b.    
         [0033]    The efficiency of a PEM electrolyzer is a function primarily of its membrane and electro-catalyst performance. The membrane  43  includes a solid fluoropolymer which has been chemically altered in part to contain sulphonic acid groups, SO 3 H, which easily release their hydrogen as positively-charged atoms or protons H + : 
         [0000]      SO 3 H-&gt;SO 3   − +H +   
         [0034]    These ionic or charged forms allow water to penetrate into the membrane structure but not the product gases, namely molecular hydrogen H 2  and oxygen O 2 . The resulting hydrated proton, H 3 O + , is free to move whereas the sulphonate ion SO 3   −  remains fixed to the polymer side-chain. Thus, when an electric field is applied across the membrane  43  the hydrated protons are attracted to the negatively charged electrode, known as the cathode  41   b . Since a moving charge is identical with electric current, the membrane  43  acts as a conductor of electricity. It is said to be a protonic conductor. 
         [0035]    A typical membrane material that is used is called “nafion”. Nafion is a perfluorinated polymer that contains small proportions of sulfonic or carboxylic ionic functional groups. 
         [0036]    Accordingly, as shown in  FIG. 5 , nonelectrolyte water  9  enters the electrolyzer  5  and is split at the surface of the membrane  43  to form protons, electrons and gaseous oxygen. The gaseous oxygen leaves the electrolyzer  5  while the protons move through the membrane  43  under the influence of the applied electric field and electrons move through the external circuit  44 . The protons and electrons combine at the opposite surface, namely the negatively charged electrode, known as the cathode  41   b , to form pure gaseous hydrogen. 
         [0037]    As shown in  FIGS. 6A and 6B , an embodiment of the hydrogen gas collector  20  includes a hydrogen collection portion  50  configured to receive the hydrogen gas and the small amount of nonelectrolyte water  9  from the electrolyzer  5 , a valve  51  is disposed in communication with the hydrogen collection portion  50 , for receiving the nonelectrolyte water  9  therein to be returned to the nonelectrolyte water tank  6 . According to one more embodiments, the valve  51  includes a valve body  53  having a first receiving section  55  at a top thereof and a second receiving section  57  formed of a through-hole  58  at a bottom thereof. Flange portions  57   a  are formed between the first receiving section  55  and the second receiving section  57 , and a return outlet  59  is provided to be connected with the water return port  24  of the nonelectrolyte water tank  6 . The valve  51  further includes a float device  60 . The float device  60  includes a top portion  61  thereof disposed within the first receiving section  55  and a bottom portion  63  thereof disposed within the through-hole  58  of the second receiving section  57 . A stopper  65  is disposed along a side surface of the bottom portion  63 . According to an embodiment, the float device  60  may be formed of a plastic material, and the stopper  65  may be formed of an elastomer material, for example. 
         [0038]    During operation of the hydrogen gas collector  20 , hydrogen gas is collected in the hydrogen collection portion  50  and any nonelectrolyte water  9  traveling with the hydrogen gas bubbles  23  is circulated to the valve body  53  to be returned to the nonelectrolyte water tank  6  via the supply means  25 . The stopper  65  is configured to stop or block the hydrogen gas from returning to the nonelectrolyte water tank  6 . As the water level in the valve body  53  rises, the float device  60  gradually floats in an upward direction as shown in  FIG. 6B , to release the nonelectrolyte water  9  in a downward direction back to the nonelectrolyte water tank  6 . Further, the hydrogen gas is released in an upward direction to a hydrogen outlet fitting  67  via a tube or other supply means  68 . 
         [0039]      FIGS. 7A and 7B  illustrate an embodiment of the cup portion  7  receiving the water container  8  as shown in  FIG. 1 . According to one or more embodiments, the receiving portion  34  of the cup portion  7  further includes a protruding portion  71  at a center thereof and a support member  73  surrounding the protruding portion  75  disposed on a bottom surface  77  thereof. 
         [0040]    In one or more embodiments, the water container  8  includes threading portions  80  on a side surface  82  thereof and a top portion  83  comprising a plurality of through-holes  85  for supply water therethrough. The water container  8  is flipped over such that the top portion  83  is inserted into the receiving portion  34 . The protruding portion  75  is configured to pierce at least one of the through-holes  85  in order to release nonelectrolyte water  9  from the water container  7 , to thereby be supplied to the nonelectrolyte water tank  6 . As shown in  FIG. 7B , the support member  73  supports the position of the top portion  83  when resting on the bottom surface  77  of the cup portion  7  and pierced by the protruding portion  75 . 
         [0041]    According to one or more embodiments, the nonelectrolyte water  9  is released from the water container  8  in intermittently or non-continuously such that when a water level of the nonelectrolyte water tank  6  reaches a predetermined level, the water container  8  discontinues the supply of nonelectrolyte water  9  into the nonelectrolyte water tank  6 , to avoid overflowing the nonelectrolyte water tank  6 . 
         [0042]    As shown in  FIG. 8 , a vehicle  86  powered by a gasoline or diesel engine  87  is equipped with the portable hydrogen supplemental system  1 . Power is supplied to the portable hydrogen supplemental system  1  by a vehicle battery  88  connected to electrical wires  89 . The electrical circuit to the portable hydrogen supplemental system  1  includes an on-board diagnostic (OBD) interface  90  in communication with the engine  87  via a vehicle OBD terminal  91  (as depicted in  FIG. 10 ), and in communication with the main power board  36  of the system  1 . The OBD interface  90  completes the electrical circuit to the portable hydrogen supplemental system  1  when the engine is running (e.g., based on the rotational speed of the vehicle  81 ). The vehicle OBD terminal  91  is used to perform self-diagnostic of the vehicle. The OBD terminal  91  enables an operator of the vehicle  86  to access to state of health information for various vehicle sub-systems. Once power is supplied to the portable hydrogen supplemental system  1 , hydrogen gas flows thru a hydrogen outlet tube  92  connected to hydrogen outlet fitting  67  of the housing unit  2  to an air intake  93  of the vehicle&#39;s engine  87 . Oxygen gas flows thru the supply means  12  and, in the case of gasoline engines with oxygen sensors, is vented to the atmosphere. The two gasses can optionally be combined for diesel engine vehicles or other internal combustion engines without oxygen sensors. 
         [0043]    An embodiment of a sub-housing or chassis  95  is illustrated in  FIG. 9 . The sub-housing  95  includes the electrolyzer  5  mounted at a lower portion  96  thereof, and the main power board  36 , the power terminals  37  and  38 , and the heat sink  39  are mounted at an upper portion  97  thereof. A heater  98  may be mounted on the sub-housing  95  or adjacent to the electrolyzer  5  for heating the nonelectrolyte water  9  when needed. The sub-housing  95  is mounted within housing  2 . The housing unit  2  being removable from the mounting bracket  3  permits the user to remove the system  1  for servicing including adding water, performing repairs, exchanging parts, and the like. 
         [0044]    The electrical circuit can, for example, be provided by a control circuit  100  as illustrated in  FIG. 10  for controlling the system  1 . The control circuit  100  includes the OBD interface  90  in communication with the vehicle OBD terminal  91  and the main power board  36 . The vehicle battery  88  is connected with the power terminals  37  and  38  at the main power board  36 . The control circuit  100  further includes a communication module  103  equipped with a global positioning system (GPS). According to one or more embodiments, the communication module  103  is a wireless module for wirelessly transmitting vehicle information via the OBD interface  90 . The OBD interface  90  is configured to receive at least one or more data output of the OBD terminal  91 , such as rotational speed (RPM) information, speed information, gas usage information, etc. When it is detected that the vehicle  86  is running, the OBD interface  90  sends a signal via the wire  89  to the main control board  36 , to operate the system  1 . For example, when the rotational speed of the engine  87  exceeds a predetermined level, a positive output is sent to the main power board  36 , thereby causing the electrolyzer  5  to operate when the engine  87  is running. The hydrogen gas may be generated based on the vehicle speed such that when the vehicle  86  exceeds a predetermined speed the electrolyzer  5  is operated to generate hydrogen gas. 
         [0045]    Other components of the system  1  are also connected with the main power board  36  via wires  104 . The other components include the electrolyzer  5 , the heater  98 , a water level sensor  105  and a temperature sensor  107 . 
         [0046]    According to one or more embodiments of the present invention, the OBD interface  90  is in communication with a database  109  (e.g., a web-based database), via the communication module  103 , for receiving vehicle information and system information including status information. The status information may include, for example, water level information from the water level sensor  105  and temperature sensor information from the temperature sensor  107 . The database  109  may further store historical data collected over time to be used to control operation or regulate maintenance of the system  1 . For example, necessary replacement of the water container  8  may be determined based on the status information of the water level within the nonelectrolyte water tank  6 .The portable hydrogen supplemental system  1  operates optimally in a gasoline powered engine when the load on the engine does not exceed a predetermined level and the amount of hydrogen produced by the portable hydrogen supplemental system  1  and supplied to the gasoline powered engine falls within a preset range. 
         [0047]    In a gasoline powered engine the electrical power used by the Hydrogen supplemental system is supplied by the engine alternator. As described above the electrical power is only supplied when the engine is operating and/or the speed of the automobile exceeds a predetermined level. Thus, the load placed on the engine by the portable hydrogen supplemental system  1  is related to the amount of electrical power drawn from the alternator as measured in amps. Optimally the portable hydrogen supplemental system  1  works best on a gasoline powered engine when the load on the engine does not exceed a current of 4 amps being drawn from the alternator, or if measured another way of 56 watts. It should be noted that the amount of amps or watts is dependent upon the size of the engine and alternator (four, six or eight cylinders, etc.). It should also be noted that diesel engines have a different optimal load setting. 
         [0048]    Further, in a gasoline powered engine the optimal amount of hydrogen produced by the Hydrogen supplemental system and supplied to the gasoline powered engine falls within a preset range of 0.10-0.25 liters per minute. 
         [0049]    Based on the above a gasoline powered automobile achieves the highest level of fuel efficiency measured in miles/gallon of gas when the load on the engine does not exceed 4 amps, or if measured another way of 56 watts, and the amount of hydrogen produced and supplied to the gasoline powered engine falls within a preset range of 0.10-0.25 liters per minute. 
         [0050]    While the invention has been described in terms of its preferred embodiments, it should be understood that numerous modifications may be made thereto without departing from the spirit and scope of the present invention. It is intended that all such modifications fall within the scope of the appended claims.