Abstract:
A safety fuel tank and filler cap apparatus is disclosed for use with a powered implement such as a lawn mower, tiller, weed trimmer or the like. The apparatus includes a locking mechanism that can be mounted on the engine body or fuel tank that disallows removal of the filler cap until the engine has cooled to a predetermined temperature that will not cause the fuel to ignite.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This is a continuation-in-part of U.S. Ser. No. 09/288,402 filed Apr. 8, 1999 now U.S. Pat. No. 6,112,714 which is a continuation in part of U.S. Ser. No. 09/267,877, filed Mar. 11, 1999 ABN, each incorporated herein by reference. 
    
    
     STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
     Not applicable 
     REFERENCE TO A “MICROFICHE APPENDIX” 
     Not applicable 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to small internal combustion engines of the type having a closely positioned fuel tank, and that are used to power outdoor implements such as mowers, tillers, lawn vacuums, weed trimmers, snow blowers, water blasters and the like. More particularly, the present invention relates to an improved safety fuel tank and filler cap apparatus that disallows removal of the fuel filler cap portion of the apparatus from the fuel tank when the engine is too hot, such as above a selected safe threshold value. 
     2. General Background of the Invention 
     The flash point of a liquid such as gasoline should not be confused with the temperature necessary to ignite the vapors, for unless a source of heat considerably hotter than the flash point of the fuel comes into direct contact with the vapors, the fuel will merely give off vapors without burning. An essential factor in the process of combustion is oxygen. Without oxygen, even the most flammable vapors will not burn. Under normal conditions, a flame draws the amount of oxygen necessary to sustain combustion from the air. When the oxygen content of the air falls below about 15%, there is an immediate extinguishment of practically all flames. There is a wide temperature difference between the flash point of a fuel and the ignition temperature. For example, the flash point (vapor given off) of gasoline is minus 43 degrees centigrade (minus 45 degrees fahrenheit), and the ignition temperature (heat necessary to ignite the mixture) is 257 degrees centigrade (490 degrees fahrenheit). A small flame can be drawn into lube oil which is at average room temperature and it will not burn, but with the addition of burning gasoline, vapors soon rise and burn to raise the temperature of the surrounding oil to the flash point. 
     Every year, fires cause serious and sometimes fatal bodily injury to operators of small outdoor or yard and garden implements such as lawn mowers, lawn vacuums, weed trimmers, water blasters and the like. One of the most common safety problems is associated with the attempt by individuals to add gasoline to the internal combustion engine of a lawn mower or like implement that is still running. Sometimes, an implement gradually loosens the gas filler cap because of vibration. Typically, these implements position the fuel tank and its filler neck very close to the engine block. Fuel that spills from the fuel tank or when filling the tank may come into contact with hot surfaces on the engine block or accessories. If the user is not paying close attention to the gas tank and its filler cap, gasoline can begin to leak when the cap is loosened. This problem is especially acute with rear drive type implements such as go-karts, riding lawn mowers and lawn tractors wherein the gasoline tank may be behind the operator or underneath a seat or hood preventing the user from seeing it. Many tractor style riding lawn mowers have such a hidden fuel tank and filler cap. 
     Many of these implements are operated by adolescent children that are not fully informed by their parents about the danger of filling fuel tanks with gasoline when the vehicle engine block is hot from operation. 
     Many manufacturers use decal warning stickers and user&#39;s manual warnings to warn a user to not remove the fuel filler cap until the engine cools for at least a couple of minutes. Despite such warnings, many users have a bad habit of smoking when operating such an implement, so that if the cap loosens, the operator does not notice the escape of fumes if the engine continues to run. 
     Generators are often filled when running because the user does not want to interrupt the flow of electricity. 
     All of these situations are hazardous if the engine continues to run when the filler cap is removed. 
     BRIEF SUMMARY OF THE INVENTION 
     The present invention provides an improved safety fuel tank and filler cap apparatus for supplying fuel to an internal combustion engine. 
     The apparatus includes an exposed fuel tank having a fill opening, a fuel filler flange surrounded by an adjoining fuel tank outer surface, the flange extending a short distance from the filler opening in the fuel tank wall. 
     A filler cap fits the fuel filler flange to form a closure of the tank at the fill opening, the filler tank and adjoining fuel tank outer surface being configured to enable a user to grip and turn the fuel filler cap. 
     A locking mechanism is interfaced between the fuel tank and filler cap that disallows removal of the filler cap. This construction prevents the user from filling the fuel tank with gasoline when the engine is still running or not running but still very hot. 
     The implement can be for example a lawn mower, go-kart, garden tractor, lawn vacuum, snow blower, tiller, chain saw, weed trimmer, hedge clipper, or log splitter. 
    
    
     BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
     For a further understanding of the nature, objects, and advantages of the present invention, reference should be had to the following detailed description, read in conjunction with the following drawings, wherein like reference numerals denote like elements and wherein: 
     FIG. 1 is a perspective view of the preferred embodiment of the apparatus of the present invention; 
     FIG. 2A is a fragmentary elevational view of the preferred embodiment of the apparatus of the present invention; 
     FIG. 2B is a fragmentary view of the preferred embodiment of the apparatus of the present invention shown in locking position; 
     FIG. 3 is a schematic top view of the preferred embodiment of the apparatus of the present invention showing the cap in an unlocked position; 
     FIG. 4 is a schematic top view of the preferred embodiment of the apparatus of the present invention showing the cap in a locked position; 
     FIGS. 5A-5B are perspective views of a second embodiment of the apparatus of the present invention; 
     FIG. 6 is a perspective view of the third embodiment of the apparatus of the present invention; 
     FIGS. 7A-7B are perspective fragmentary views of a fourth embodiment of the apparatus of the present invention; 
     FIG. 8 is a schematic view of a fifth embodiment of the apparatus of the present invention; and 
     FIG. 9 is an schematic view of a sixth embodiment of the apparatus of the present invention. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     FIGS. 1-2B show the preferred embodiment of the apparatus of the present invention designated generally by the numeral  10  in FIG.  1 . Safety fuel tank and cap apparatus  10  in FIG. 1 is used with an internal combustion engine  11 , such as a lawn mower engine having a starter  12 , starter solenoid  13 , and powered by battery  14 . 
     Engine  11  has a fuel tank  21  that is often closely positioned to the engine block  11 A of engine  11 . Fuel tank  21  has an opening for enabling fuel to be added, and a fuel filler closure cap  22  that can seal the fuel tank opening. This overall arrangement of engine  11 , battery  14 , fuel tank  21  is the same for all embodiments. 
     Wiring interconnecting battery  14 , engine  11  and the remaining components of the apparatus  10  of the present invention are shown in FIG.  1 . Such wiring includes ground  15  that communicates with battery  14  via battery cable  16  and cable  17  that communicates with starter solenoid  13 . Cable  18  extends between battery  14  and heat sensor  19 . A cable is also provided that links starter  12  and starter solenoid  13 . 
     Cable  20  extends between heat sensor  19  and actuator  23 . Actuator  23  is preferably mounted upon fuel tank  21  next to fuel filler cap  22  as shown in FIG.  1 . The actuator  23  defines a locking mechanism that prevents the filler cap  22  from being removed when the engine temperature is above a predetermined temperature that is near or below the ignition temperature of the fuel (or fuel vapor) in and around tank  21 . 
     Actuator  23  includes switch housing  24  having a housing interior  25  that contains plunger  30 , as shown in FIGS. 2A and 2B. Wire lead  26  is contained within cable  20  for supplying electrical power to actuator  23  as shown in FIGS. 2A and 2B. 
     Wire lead  26  connects to coil  28  at terminal  27 . Coil  28  is preferably grounded, eg. with wire lead  29  to switch housing  24 . 
     Plunger  30  moves between locked and unlocked positions. FIG. 2A shows the unlocked position of plunger  30 . FIG. 2B shows the locked position of plunger  30 . Plunger  30  is mounted within housing interior  25  through an opening at the center of coil  28 . One end of plunger  30  is supported by flange  31  and spring  32 . The other end of plunger  30  is supported by housing  24  at the opening through which plunger  30  extends. The actuator  23  functions as a solenoid to move the plunger  30  between locking and unlocking positions. Spring  32  normally holds plunger  30  in the unlocked position of FIG.  2 A. The spring  32  extends between anchor plate  33  and plunger  30  at flange  31 . 
     Cap  22  has a plurality of circumferentially spaced radially extending recesses  35 , each sized and shaped to form a connection with plunger  30  at end portion  36 . In FIG. 2B, arrows  34  indicate the movement of plunger  30  from an unlocked position to a locked position. During operation, heat sensor  19  monitors the temperature of engine  11 . When the temperature of engine block  11 A of engine  11  reaches a predetermined temperature that is at or near the ignition temperature of gasoline, heat sensor  19  sends an electrical signal via wire lead  26  to actuator  23  activating coil  28  to move plunger  30  to the locked position of FIG.  2 B. When the temperature sensed by heat sensor  19  drops below a predetermined acceptable temperature value, the heat sensor  19  halts the electrical flow to actuator  23  so that return spring  32  moves plunger  30  to the unlocked position of FIG.  2 A. 
     FIGS. 3 and 4 show a second embodiment  10 A of the apparatus of the present invention using switch  37 . Switch  37  is in the form of a coil  38  having contact bar  39 . A pair of terminals  40 ,  41  are positioned next to contact bar  39  as shown in FIGS. 3 and 4. When excessive heat indicated by heat wave lines  42  in FIG. 4 is transferred to switch  37 , coil  38  expands, pushing contact bar  39  into contact with terminals  40 ,  41 . As the circuit is closed, battery  14  is able to supply power to actuator  23 , closing a circuit activating plunger  30  and engaging the projecting portion  36  into a recess  35  of cap  22  an indicated by arrow  34  in FIG.  4 . 
     Another embodiment of the apparatus  10 B of the present invention is shown in FIGS. 5A and 5B. In FIGS. 5A and 5B, cap  43  is mounted upon hinge  44  to move between open and closed positions as indicated by arrow  46  in FIG.  5 B. Latch  45  can be used to latch cap  43  in the closed position of FIG.  5 A. The latch  45  can be depressed to open cap  43  as shown in FIG.  5 B. Cap  43  closes opening  48  that is surrounded by filler neck  47 . In the embodiment of FIGS. 5A and 5B, the actuator  23  and its plunger  30  are operated in the same fashion as shown and described herein relative to FIGS. 2A and 2B. However, in FIGS. 5A and 5B, the plunger  30  simply extends over cap  43  preventing it from opening. In FIG. 5B, when the plunger  30  is retracted as indicated by arrow  49 , cap  43  can be opened. 
     In the embodiment of FIG. 6, apparatus  10 C includes cap  50  is an internally threaded cap having internal threads that engage the external threads of a filler neck on fuel tank  21 . As with the embodiment of FIGS. 5A and 5B, the embodiment of FIG. 6 extends the plunger  30  into a locking position to prevent a user from unthreading the cap  50  from its filler neck until the engine  11  has cooled below the desired temperature. 
     In FIGS. 7A and 7B, another embodiment of the apparatus of the present invention is shown, designated as  10 D. In FIGS. 7A and 7B, the plunger  30  carries an enlarged end portion  51  having a rubber or resilient contact member  52 . The rubber contact member  52  engages ribbed cap  53 . The ribs  54  are sharp so that they are gripped by the resilient or rubber contact member  52  that conforms generally to the ribs. 
     The contact member  52  has a concave surface  55  that generally fits the contour of the external surface of the cap  53 . In FIG. 7B, arrow  56  indicates movement of plunger  30  to an unlocked position. 
     In the embodiment of FIG. 8, the apparatus  10 E includes a timer arrangement used in concert with the actuator  23  of FIGS. 2A and 2B for locking fuel cap  22  until the temperature of the engine block  11 A of engine  11  has cooled. In FIG. 8, a timer  57  locks the cap  22  until a sufficient amount of time has the lapsed (2-5 minutes) so that the cap can be removed without a danger of explosion or fire. In FIG. 8, key switch  58  has key  59  for operating engine ignition and timer  57 . When key  59  is turned to the “on” position, a timer circuit activates actuator  23  so that plunger  30  is moved to the locked position, and remains locked as long as the key is in the on position. When key  59  is turned to the “off” position, timer  57  is activated to keep plunger in locked position. After a desired time interval of two to five minutes for example, timer  57  halts the flow of electricity from battery  14  to actuator  23  so that its return spring  32  (see FIGS. 2A-2B) moves the plunger to the unlocked position shown in FIG.  8 . Wire cables  60 - 64  are shown in FIG. 8 interfacing battery  14 , lock  58 , timer  57  and actuator  23 . 
     In FIG. 9, the apparatus  1 OF includes plunger  65  that is manually operated using heat sensitive coil  69 . Plunger  65  is mounted in switch housing  66 . Plunger  30  is attached to cable  67 . The cable  67  extends out of the switch housing  66  to engage radial arm  70  of coil  69 . Coil housing  68  contains coil  69  and also provides a stop for limiting movement of free end  72  of radial arm  70 . Arrow  71  in FIG. 9 indicates the movement of radial arm  70  and its free end  72  between a locking position shown in hard lines in FIG.  9  and an unlocked position shown in phantom lines in FIG.  9 . In FIG. 9, the heat indicated by waves  42  causes coil  69  to expand to the locked position shown in FIG.  9 . When the heat of the engine reduces to an acceptable temperature level, coil  69  cools and contracts, moving radial arm  70  to the unlocked position shown in phantom lines in FIG.  9  and pulling cable  67  and plunger  65  with it. 
     PARTS LIST 
     The following is a list of parts and materials suitable for use in the present invention: 
     NUMBER PART DESCRIPTION 
       10  safety fuel tank and cap apparatus 
       10 A safety fuel tank and cap apparatus 
       10 B safety fuel tank and cap apparatus 
       10 C safety fuel tank and cap apparatus 
       10 D safety fuel tank and cap apparatus 
       10 E safety fuel tank and cap apparatus 
       10 F safety fuel tank and cap apparatus 
       11  engine 
       11 A engine block 
       12  starter 
       13  starter solenoid 
       14  battery 
       15  ground 
       16  battery cable 
       17  battery cable 
       18  battery cable 
       19  heat sensor 
       20  cable 
       21  fuel tank 
       22  fuel cap 
       23  actuator 
       24  actuator housing 
       25  housing interior 
       26  wire lead 
       27  terminal 
       28  coil 
       29  wire lead 
       30  plunger 
       31  flange 
       32  spring 
       33  anchor plate 
       34  arrow 
       35  recess 
       36  projecting end 
       37  switch 
       38  coil 
       39  contact bar 
       40  terminal 
       41  terminal 
       42  heat 
       43  cap 
       44  hinge 
       45  latch 
       46  arrow 
       47  filler neck 
       48  opening 
       49  arrow 
       50  cap 
       51  enlarged end portion 
       52  rubber contact member 
       53  ribbed cap 
       54  rib 
       55  concave surface 
       56  arrow 
       57  timer 
       58  key switch 
       59  key 
       60  wire cable 
       61  wire cable 
       62  wire cable 
       63  wire cable 
       64  wire cable 
       65  plunger 
       66  plunger housing 
       67  cable 
       68  coil housing 
       69  heat sensitive coil/bi-metal spring 
       70  radial arm 
       71  arrow 
       72  free end 
       73  stop position 
     All measurements disclosed herein are at standard temperature and pressure, at sea level on earth, unless indicated otherwise. 
     The going embodiments are presented by way of example only; the scope of the present invention is to be limited only any the following claims.