Abstract:
A forced air heater that includes two air moving devices for improved control of air and fuel mixture for combustion, and improved air flow the heater. In addition to better air flow, the heater includes an improved fuel system that utilizes a pump and delivery controls to accommodate reduced air flow while avoiding incomplete combustion and fume odors.

Description:
[0001]    This application claims the benefit of U.S. Provisional Application No. 61/711,624, which was filed Oct. 9, 2012 and is incorporated herein by reference as if fully set forth. 
     
    
     FIELD OF INVENTION 
       [0002]    This application generally relates to forced air heaters, and more particularly to a forced air heater with twin air movers that control the flow of air through and over the heater combustion chamber. 
       BACKGROUND 
       [0003]    Typically a forced air heater involves the use of a fan for pulling ambient air through and over the combustion chamber. As the air flows through the chamber, it is introduced to a fuel source and an ignition source. The ignition source, commonly a spark plug, combusts the fuel to release heat into the air flow. 
         [0004]    Some forced air heaters are only capable of delivering a single speed air flow. While effective for some heating purposes, a single air flow inside a forced air heater does not offer the desired control of the air flow through the heater. This can produce an uncomfortable condition in the area heated by the forced air heater as the space can become too hot and dry. Simply turning off the forced air heater is not really a viable solution as it allows cold temperatures to quickly penetrate the area. Additionally, reducing the air flow can result in incomplete combustion, unburned fuel, and fumes. 
         [0005]    There exist a need for a forced air heater with improved fuel delivery and air flow control through and over the heater combustion chamber. 
       SUMMARY 
       [0006]    The disclosed forced air heater includes two air moving devices. A first air moving device at a first axial end of the housing is provided to primarily direct the air through an annular space defined between the outer surface of the combustion chamber and the inner surface of the housing. The air heated by the combustion chamber is directed out of the heater through a second axial end of the housing. A second air moving device is provided for supplying air directly to the combustion chamber. The second air moving device has an intake port and an outlet port that both face the combustion chamber. The inlet port draws air into the second air moving device. The outlet port moves air into a duct that directs the air into the combustion chamber. The first air moving device primarily directs heated air out of the heater. In addition to better air flow, a preferred heater includes a pump and delivery controls that accommodate reduced air flow and avoids incomplete combustion and fume odors. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS  
         [0007]    The invention is described in more detail with reference to the accompanying drawings. 
           [0008]      FIG. 1  is a perspective view of the forced air heater according to the invention. 
           [0009]      FIG. 2  is an exploded view of the forced air heater in  FIG. 1 . 
           [0010]      FIG. 3  is a further exploded view of a forced air heater according to the invention. 
           [0011]      FIG. 4A  is an exploded, detailed view of air moving devices according to the invention. 
           [0012]      FIG. 4B  is an exploded view of an in tank fuel pump system suitable for use with the heater of  FIG. 1 . 
           [0013]      FIG. 5  is an exploded view of a heater according to the invention with an external fuel pump. 
           [0014]      FIG. 6  is an exploded view illustrating more details of a forced air heater according to the invention with an on board battery power source. 
           [0015]      FIG. 7  is a perspective view of a heater including a mechanical pump. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0016]    Referring to  FIG. 1 , there is shown a forced air heater  100  that includes a housing  105  that is comprised of an upper shell  110  and a bottom shell  115 . The upper shell  110  is detachable for servicing of the forced air heater  100 . A control panel  120  is located on the upper shell  110 . The housing  105  is mounted on a support structure  130  that rests on a fuel tank  125 . A deflector  135  attaches over the air exhaust end of the forced air heater  100 . The deflector  135  includes a center deflection plate and a plurality of tabs  136  for connecting to the housing  105 . An annular space  137  is defined between a radially inner surface of the housing  105  and a radially outer surface of a combustion chamber  500 , see  FIG. 2 . As explained in more detail below, an air moving device provides airflow through this annular space  137 . 
         [0017]    In one embodiment, the heater  100  is made transportable by the inclusion of a handle  145 , hand grips  150 , and wheels  140 , see  FIGS. 1 and 3 . The hand grips  150  include caps  152  that provide gripping surfaces during transport and help keep the heater  100  in place when it is at rest. 
         [0018]    Referring to  FIG. 2 , there is shown a view of the forced air heater  100  with the upper shell  110  of the housing  105  pulled away from the heater  100  to reveal the internal components. A portion of the fuel tank  125  has also been cutaway in  FIG. 2  to show a preferred fuel supply system  300 . The forced air heater  100  comprises an air system  200 , the fuel supply system  300 , an ignition system  400 , and the combustion chamber  500 . Air is drawn into the forced air heater  100  at a first axial end  106  of the housing  105  by the air system  200 . Owing to dual air moving devices, the air system  200  directs air towards a second axial end  107  of the housing  105  towards the ignition system  400  and the combustion chamber  500 . By providing two separate airflows, the heater  100  provides improved control of heat output. The fuel supply system  300  pumps fuel from the fuel tank  125  to the ignition system  400 , via a fuel line  305 , where fuel mixes with air, ignites, and expands into the combustion chamber  500  while burning. 
         [0019]    Referring to  FIGS. 2 ,  3 , and  4 A, there is shown an exploded view of the internal components found inside the housing  105  of a preferred embodiment of the forced air heater  100 .  FIG. 3  focuses on the air system  200  components and the ignition system  400  components. As more clearly shown in  FIGS. 2 and 4A , the air system  200  is further comprised of a fan guard  205 , a first air moving device  210 , a motor  215 , a second air moving device  220 , and an air duct  225 . The first air moving device  210  is located at the first axial end  106  of the housing  105 . The motor  215  is driven by a power source, such as an AC power source via a plug  610  or a battery  605 . Air is drawn into the first axial end  106  of the housing  105  by the first air moving device  210  and a portion of that air is drawn into an inlet  222  of the second air moving device  220  for movement into the combustion chamber  500 . The remainder of the air continues through the forced air heater  100 , into the annular space  137  around the combustion chamber  500 , towards the second axial end  107  of the housing  105 , and out to the area to be heated. 
         [0020]    In one embodiment, the first air moving device  210  is a blade fan and the second air moving device  220  is a squirrel cage blower, or Sirroco fan. The first air moving device  210  is a commonly known blade fan with a plurality of blades. Suitable squirrel cage blowers  220  are available from Grainger Industrial Supply, Lake Forest, Ill. The squirrel cage blower  220  has an air intake port  222 , an air outlet port  223 , and an internal air mover  224 . The air mover  224  draws air into intake port  222  and the outlet port  223  moves air into the air duct  225 , which directs the airflow into the combustion chamber  500 . The air duct  225  is shaped to direct the full output of air from the squirrel cage blower  220  into the combustion chamber  500 . In a preferred embodiment, the air duct  225  is configured to direct the air into a central portion of the combustion chamber  500 . The air duct  225  can be a rigid elbow shaped duct, a flexible tube, or hose that can be shaped to direct air from the second air moving device  220  into the combustion chamber  500 . It will be recognized that that the configuration of the air mover will determine whether an air duct  225  is necessary and, if necessary, the shape that is required to deliver the air to a central location of the combustion chamber. 
         [0021]    The first and second air moving devices  210 ,  220  are driven by a common drive shaft  230  in the motor  215 . In a preferred embodiment, the first air moving device  210  is located on one side of the motor  215 , and the second air moving device  220  is located on an opposite side of the motor  215 . Each air moving device  210 ,  220  is secured to a respective end  235 ,  240  of the drive shaft  230  so that they rotate about a common axis. In one embodiment, the motor  215  rotates the entire shaft  230  at a single speed, and the first and second air moving devices  210 ,  220  are driven at the same speed. In another embodiment, the shaft  230  is segmented and the assembly includes a clutch assembly  245  which allows the first end of the shaft  235  to rotate at a first speed, and the second end of the shaft  240  to rotate at a second, different speed, see  FIG. 4A . In another embodiment, the clutch assembly  245  is located between the motor  215  and the second air moving device  220 . In one embodiment, the first air moving device  210  is driven directly by the motor  215  via the drive shaft  230 . On an opposite side of the motor  215 , the clutch assembly  245  reduces the output from the motor  215  being provided to the second air moving device  220  via the drive shaft  230 , such that the second air moving device  220  rotates at a lower speed than the first air moving device  210 . The clutch assembly  245  can be located on either side of the motor  215 , either between the motor  215  and the second air moving device  220 , or between the motor  215  and the first air moving device  210 . 
         [0022]    The clutch assembly  245  can be self-actuating or actuated by the power source, such that the clutch assembly  245  can be variably engaged or disengaged via the control panel  120 . The motor  215  is controlled via the control panel  120 . In those embodiments of the air system  200  having a variable speed motor, the speed of the motor  215  can also be controlled via the control panel  120 . The individual speeds of the first and second air moving devices  210 ,  220  can also be adjusted via the control panel  120 . In another embodiment, two motors can be provided, with a first motor driving a first shaft connected to the first air moving device  210 , and a second motor driving a second shaft connected to the second air moving device  220 . 
         [0023]    Referring again to  FIGS. 2 and 3 , the ignition system  400  is further comprised of a fuel nozzle  405 , an ignition source  410 , and a mist diffuser  415 . In a preferred embodiment, the ignition source  410  is a spark plug. Other ignition sources can be used, including, but not limited to, a piezoelectric igniter, a hot surface igniter or an ignition transformer igniter. Fuel is supplied to the ignition system  400  by a fuel line that is supplied from the fuel tank  125 . Fuel exits the fuel line through the fuel nozzle  405 , which is directed into the mist diffuser  415  where it creates an air-fuel mixture. The air-fuel mixture is exposed to the ignition source  410  as the air-fuel mixture is ejected into the combustion chamber  500 . 
         [0024]    The forced air heater ignition system  400  also comprises a photo cell  420  and a thermal sensor  425 , both of which are associated with the combustion chamber  500  to detect chamber temperatures. The thermal sensor  425  can comprise an overheating sensor, such as a bimetallic thermal switch. In the event that the photo cell  420  is unable to detect the presences of a flame in the combustion chamber, the forced air heater will shut off. Similarly, the thermal sensor  425  will detect the temperature in the combustion chamber. In the event that the combustion chamber  500  overheats, the forced air heater  100  will shut off. 
         [0025]    Returning to  FIG. 2 , there is also shown an embodiment of the fuel supply system  300  and its incorporation into the forced air heater  100 . The fuel is pumped out of the fuel tank  125  to the ignition system  400  by a fuel supply system  300  via the fuel line  305 . The fuel line  305  is interrupted by an adjuster  320 , which is a controller that can be manipulated by a user to adjust the amount of fuel flow from the fuel supply system  300  to the ignition system  400 . The amount of fuel supplied to the pump  360  can be increased or decreased via the heat capacity adjuster  320 . The heat capacity adjuster  320  can include a printed circuit board that controls the pump. An ignition button  315  can also be provided. 
         [0026]    Referring now to  FIG. 4B , there is shown an exploded view of the fuel supply system  300 . The fuel supply system  300  comprises a fuel pump assembly  350  and the fuel line  305  (shown in  FIG. 2 ). The fuel pump assembly  350  is further comprised of a fuel strainer  355 , a fuel pump  360 , a fuel tube  365 , a fuel tube band  370 , a fuel pump bracket  375  and a power connector  380 . The fuel strainer  355  is attached to the bottom of the fuel pump  360 . The fuel tube  365  is located inside of the fuel pump  360  and both the fuel pump  360  and the fuel tube  365  are connected to a fuel pump bracket  375 . The fuel tube band  370  serves as a fastener between the fuel tube  365  and the fuel pump bracket  375 , while the fuel pump  360 , itself, connects to the fuel pump bracket  375 . The fuel pump assembly  350  is submergible inside the fuel tank  125 . The pump  360  requires power to operate, which is facilitated by the power connector  380  that is connected to a power source, such as battery  605 . When connected to the fuel pump  360 , the power connector  380  forms a liquid-tight seal. In an alternative embodiment of the fuel supply system  300 , a high pressure pump can be used to pump fuel from the fuel tank  125  to the ignition system. 
         [0027]    In another embodiment, shown in  FIG. 5 , the fuel supply system  300  includes a commonly known centrifugal or vane pump  362  that is external to the fuel tank  125 . In this embodiment, the pump  362  is located adjacent to the motor  215  and is powered by the motor  215 . The pump  362  is provided with a suction line that connects to the ignition system  400 . The pump  362  provides suction that draws fuel from the fuel tank  125  via the fuel line  305  into the ignition system  400 . In another embodiment, shown in  FIG. 7 , the fuel supply system  300  can include a mechanical pump  364 . The mechanical pump  364  is positioned directly above the fuel tank  125  and includes a suction line  366  in the fuel tank  125 . The mechanical pump  364  draws fuel from inside the tank  125  and a fuel supply line  368  that connects to the ignition system  400 . 
         [0028]    Referring now to  FIG. 6 , there is shown an embodiment of the forced air heater  100  that is capable of battery operation. While forced air heaters typically operate on AC power, an embodiment of the device preferably uses a rechargeable battery  605  with a charging system, whereby the battery is recharged each time the heater  100  is plugged into an AC power source. The device can incorporate an AC to DC converter and a DC to AC inverter, thus either power source—AC or DC—can power the heater  100 . 
       Embodiments 
       [0029]    The following list includes particular embodiments of the present invention. The list, however, is not limiting and does not exclude alternate embodiments, as would be appreciated by one of ordinary skill in the art. 
         [0000]    1. A forced air heater comprising:
 
an outer housing having interior and exterior surfaces and first and second axial ends;
 
a combustion chamber positioned within the housing with an annular space defined between the interior surface of the housing and the combustion chamber;
 
an ignition system within the combustion chamber;
 
a first air mover that draws air in from the first axial end of the outer housing, through the annular space and towards the second axial end of the outer housing;
 
a second air mover that directs air to the ignition system;
 
a fuel source; and
 
a fuel supply system that provides fuel to the ignition system.
 
2. The heater of embodiment 1 wherein the first air mover is a blade fan and the second air mover is a cage blower.
 
3. The heater of any one or more of embodiments 1-2 wherein the second air mover includes an inlet port for drawing air into the second air mover, and an outlet port that is connected configured to a central portion of the combustion chamber.
 
4. The heater of any one or more of embodiments 1-3 wherein the first and second air movers are driven by a common motor.
 
5. The heater of any one or more of embodiments 1-4 wherein a common shaft extending through the common motor is connected to the first and second air movers.
 
6. The heater of any one or more of embodiments 1-5 wherein the first and second air movers are connected on opposite sides of the motor.
 
7. The heater of any one or more of embodiments 1-6 wherein a clutch assembly is associated with at least one of the first and second air movers.
 
8. The heater of any one or more of embodiments 1-7 wherein the motor is a variable speed motor.
 
9. The heater of any one or more of embodiments 1-8 wherein the ignition system is further comprised of a fuel nozzle, an ignition source, and a mist diffuser.
 
10. The heater of any one or more of embodiments 1-9 wherein the ignition source is a spark plug.
 
11. The heater of any one or more of embodiments 1-10 wherein the heater is adapted for operating on AC or DC power.
 
12. The heater of any one or more of embodiments 1-11 wherein the fuel system includes a submerged pump.
 
13. The heater of any one or more of embodiments 1-12 wherein the fuel system includes an external pump selected from the group comprised of a vane pump, a centrifugal pump, and a mechanical pump.
 
14. The heater of any one or more of embodiments 1-13 wherein the pump is powered by the motor.
 
15. The heater of any one or more of embodiments 1-14 wherein the fuel system includes an adjuster for altering the fuel supply.
 
16. The heater of any one or more of embodiments 1-15 wherein the first and second air movers are independently adjustable.
 
17. The heater of any one or more of embodiments 1-16 wherein the heater includes a thermal sensor.
 
18. A forced air heater comprising:
 
an outer housing having interior and exterior surfaces and first and second axial ends;
 
a combustion chamber positioned within the housing with an annular space defined between the interior surface of the housing and the combustion chamber;
 
an ignition system within the combustion chamber;
 
a first air mover that is located within the outer housing and draws air in from the first axial end of the outer housing, through the annular space and towards the second axial end of the outer housing;
 
a second air mover that is located in the outer housing and directs air to the ignition system;
 
a fuel source; and
 
a fuel supply system that includes a submerged pump provides fuel to the ignition system.
 
19. A forced air heater comprising:
 
an outer housing having interior and exterior surfaces and first and second axial ends;
 
a combustion chamber positioned within the housing with an annular space defined between the interior surface of the housing and the combustion chamber;
 
an ignition system within the combustion chamber;
 
a first air mover that is located within the outer housing and draws air in from the first axial end of the outer housing, through the annular space and towards the second axial end of the outer housing;
 
a second air mover that is located in the outer housing and directs air to the ignition system;
 
a fuel source; and
 
a fuel supply system that includes an external mechanical pump provides fuel to the ignition system.
 
20. A forced air heater comprising:
 
an outer housing having interior and exterior surfaces and first and second axial ends;
 
a combustion chamber positioned within the housing with an annular space defined between the interior surface of the housing and the combustion chamber;
 
an ignition system within the combustion chamber;
 
a first air mover that draws air in from the first axial end of the outer housing, through the annular space and towards the second axial end of the outer housing;
 
a second air mover that directs air to the ignition system;
 
a motor that is connected to the first and second air movers by a common shaft;
 
a fuel source; and
 
a fuel supply system that provides fuel to the ignition system.
 
         [0030]    Further embodiments herein may be formed by supplementing an embodiment with one or more element from any one or more other embodiment herein, and/or substituting one or more element from one embodiment with one or more element from one or more other embodiment herein. 
         [0031]    Having thus described various embodiments of the present invention in detail, it is to be appreciated and will be apparent to those skilled in the art that many physical changes, only a few of which are exemplified in the detailed description above, could be made in the device without altering the inventive concepts and principles embodied therein. The present embodiments are therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore to be embraced therein.