Abstract:
A heater includes a handle, a combustion chamber, a valve and a thermal controller. A reservoir for fuel can be installed in the handle. The combustion chamber is mounted on the handle. The valve is received in the handle. The valve defines a passage through which fuel can flow from the reservoir into the combustion chamber for combustion. The thermal controller includes a memory element at least partially received in the combustion chamber and a rod connected between the memory element and the valve for controlling a rate at which fuel can flow through the passage defined in the valve based on the temperature in the combustion chamber. The memory element is a helical memory metal element. The memory element shrinks or expands when the temperature increases above a certain value.

Description:
BACKGROUND OF INVENTION 
   1. Field of Invention 
   The present invention relates to a personal heater and a valve for use in the same. 
   2. Related Prior Art 
   U.S. Pat. No. 5,800,154 discloses a gas-heated appliance for personal use including a fuel gas reservoir, a combustion chamber, and a valve assembly disposed between the fuel gas reservoir and the combustion chamber for controlling and/or regulating the amount of fuel gas supplied, in particular in dependence upon temperature. A valve housing ( 4 ) defines a gas passageway ( 5 ,  15 ,  16 ). A sealing element ( 6 ) and a partition wall ( 13 ) are received in the passageway ( 5 ,  15 ,  16 ). The sealing element ( 6 ) includes an elastic tongue ( 37 ). The partition wall ( 13 ) defines a gas orifice ( 17 ) corresponding to the elastic tongue ( 37 ). An actuator ( 7 ) includes a rod ( 8 ) with a tip ( 19 ) inserted through the gas orifice ( 17 ) for engagement with the elastic tongue ( 37 ). The tip ( 19 ) positions the elastic tongue ( 37 ) based on the temperature. However, the elastic tongue ( 37 ) can be broken due to fatigue. 
   The present invention is therefore intended to obviate or at least alleviate the problem encountered in the prior art. 
   SUMMARY OF INVENTION 
   It is the primary objective of the present invention to provide a durable heater. 
   According to the present invention, a heater includes a handle, a combustion chamber, a valve and a thermal controller. A reservoir for fuel can be installed in the handle. The combustion chamber is mounted on the handle. The valve is received in the handle. The valve defines a passage through which fuel can flow from the reservoir into the combustion chamber for combustion. The thermal controller includes a memory element at least partially received in the combustion chamber and a rod connected between the memory element and the valve for controlling a rate at which fuel can flow through the passage defined in the valve based on the temperature in the combustion chamber. The memory element is a helical memory metal element. The helical memory metal element shrinks or expands when the temperature increases above a certain value. 
   Other objectives, advantages, and novel features of the invention will become more apparent from the following detailed description when taken in conjunction with the attached drawings. 

   
     BRIEF DESCRIPTION OF DRAWINGS 
     The present invention will be described through detailed illustration of embodiments referring to the attached drawings. 
       FIG. 1  is a front view of a personal heater equipped with a valve according to the present invention. 
       FIG. 2  is similar to  FIG. 1  but showing a portion cut from the personal heater in order to show the valve. 
       FIG. 3  is a side view of the personal heater of  FIG. 1 , showing a portion cut from the personal heater in order to show a valve according to a first embodiment of the present invention. 
       FIG. 4  is an exploded view of the valve of FIG.  3 . 
     FIGS.  5 ˜ 7  are cross-sectional views of the valve of  FIG. 3  in various positions. 
     FIGS.  8 ˜ 10  are cross-sectional views of a valve in various positions according to a second embodiment of the present invention. 
   

   DETAILED DESCRIPTION OF EMBODIMENTS 
   Referring to FIGS.  1 ˜ 7 , according to a first embodiment of the present invention, a personal heater  10  includes a handle  14  that is hollow so as to receive a reservoir (not shown), a switch  11  movably mounted on the handle  14 , a combustion chamber  12  mounted on the handle  14 , a valve  20  received in the handle  14 , a mechanical controller  60  via which the valve  20  is connected with the switch  11  and a thermal controller  70  engaged with the valve  20 . 
   The valve  20  includes an upper shell  30 , a lower shell  40  and a membrane  50  sandwiched between the upper shell  30  and the lower shell  40 . 
   The upper shell  30  includes an upper face and a lower face. A hole  31  extends through the upper shell  30  from the lower face to the upper face. A pipe  80  includes a lower end inserted in the hole  31  and an upper end inserted in the combustion chamber  12 . Thus, fuel can flow from a reservoir (not shown) into the combustion chamber  12  through the valve  20 . A hole  33  extends through the upper shell  30  from the lower face to the upper face. The hole  33  includes a reduced upper end, thus forming an annular shoulder  34 . A hole  35  extends through the upper shell  30  from the lower face to the upper face. 
   The mechanical controller  60  includes a rod  61 , a beam  62  and a spring  63 . The rod  61  includes an upper end and an enlarged lower end. The spring  63  is mounted on the rod  61 . A substantial portion of the rod  61  is inserted in the hole  33  together with the spring  63 . Thus, the spring  63  is compressed between the annular shoulder  34  and the enlarged lower end of the rod  61 . The upper end of the rod  61  is located beyond the hole  33 . The beam  62  includes a first end secured to the upper end of the rod  61  and a second end in engagement with the switch  11 . In a conventional manner, the manipulation of the switch  11  causes movement of the beam  62  and the rod  61 . 
   The membrane  50  includes a valve portion  53  corresponding to the hole  33  and a bowl-shaped portion  55  corresponding to the hole  35 . The valve portion  53  includes a concave upper face and a convex lower face. The bowl-shaped portion  55  includes a concave upper face and a convex lower face. A hole  51  extends through the bowl-shaped portion  55 . The membrane  50  includes an upper face and a lower face. A channel  57  is defined in the upper face of the membrane  50 . A space defined in the bowl-shaped portion  55  is communicated with the channel  57 . 
   The lower shell  40  includes an upper face and a lower face. A channel  42  is defined in the upper face of the lower shell  40 . A hole  43  extends through the lower shell  40  from the lower face to the upper face. The lower shell  40  includes a bowl-shaped portion  45  with a concave upper face and a convex lower face. Via the channel  42 , the hole  43  is communicated with a space defined in the bowl-shaped portion  45 . 
   The membrane  50  is sandwiched between the upper shell  30  and the lower shell  40  and they are assembled. The valve portion  53  is located between the hole  33  and the hole  43 . The bowl-shaped portion  55  is received in the bowl-shaped portion  45  so that the space defined therein is communicated with hole  35 . The hole  31  is communicated with the channel  57 . 
   The thermal controller  70  includes a sleeve  71  mounted on the upper shell  30  and a rod  72  inserted in the sleeve  71 . The rod  72  includes a lower end inserted in the hole  35  and an upper end located beyond the sleeve  71 . A helical memory metal element  73  is mounted on the rod  72 . A head  76  is secured to the upper end of the rod  72  so that the helical memory metal element  73  is compressed between the sleeve  71  and the head  76 . A helical memory metal element  74  is compressed between the head  76  and a stop  16  formed on an internal face of the combustion chamber  12 . 
   Referring to  FIG. 5 , the switch  11  is turned to OFF. Biased via the spring  63 , the rod  61  presses the valve portion  53  so as to shut the hole  43 . Thus, fuel does not flow from the reservoir into the valve  20 . 
   Referring to  FIG. 6 , the switch  11  is turned to ON. Lifted via the switch  11 , the rod  61  releases the valve portion  53  so as to open the hole  43 . Thus, fuel flows from the reservoir into the valve  20 . Through the channel  42 , fuel flows from the hole  43  to the space defined in the bowl-shaped portion  45 . Through the hole  51 , fuel flows from the space defined in the bowl-shaped portion  45  to the space defined in the bowl-shaped portion  55 . Through the channel  57 , fuel flows from the space defined in the bowl-shaped portion  55  to the hole  31 . Through the pipe  8 , fuel flows from the hole  31  into the combustion chamber  12  for combustion. 
   When the combustion begins, the temperature in the combustion chamber  12  is not increased significantly. The helical memory metal element  73  does not substantially shrink. The helical memory metal element  74  does not substantially expand. A gap between the lower end of the rod  72  and the bottom of the bowl-shaped portion  55  is at its substantially maximum value. Thus, fuel can flow through this gap at a substantially maximum rate. 
   Referring to  FIG. 7 , when the combustion continues in the combustion chamber  12  for some time, the temperature increases in the chamber  12 . The helical memory metal element  73  shrinks while the helical memory metal element  74  expands. The rod  72  is moved down so that the gap between the lower end of the rod  72  and the bottom of the bowl-shaped portion  55  is reduced. Thus, fuel flows through this gap at a reduced rate, and the combustion continues at a reduced scale. 
   When the switch  11  is turned to OFF, fuel is not allowed to enter the combustion chamber  12 . Thus, the combustion is ceased. Accordingly, the temperature decreases in the combustion chamber  12 . Inherently, the helical memory metal element  73  expands while the helical memory metal element  74  shrinks. The helical memory metal elements  73  and  74  return to their original positions as the temperature decreases to a certain value in the combustion chamber  12 . 
   FIGS.  8 ˜ 10  show a valve according to a second embodiment of the present invention. The second embodiment is different from the first embodiment in that the helical memory metal element  73  is located above the head  76  and the helical memory metal element  74  is located below the head  76  and that a head  78  is attached to the lower end of the rod  72  and located below the membrane  50 . Thus, the helical memory metal elements  73  and  74  lift the rod  72  when the temperature increases in the combustion chamber  12 . Accordingly, a gap between the head  78  and the membrane  50  is reduced. 
   Referring to  FIG. 8 , the switch  11  is turned to OFF. Biased via the spring  63 , the rod  61  presses the valve portion  53  so as to shut the hole  43 . Thus, fuel does not flow from the reservoir into the valve  20 . 
   Referring to  FIG. 9 , the switch  11  is turned to ON. Lifted via the switch  11 , the rod  61  releases the valve portion  53  so as to open the hole  43 . Thus, fuel flows from the reservoir into the valve  20 . Via the channel  42 , fuel flows from the hole  43  to the gap between the head  78  and the membrane  50 . Via the hole  51  and the channel  57 , fuel flows from the gap between head  78  and the membrane  50  to the hole  31 . Via the pipe  80 , fuel flows from the hole  31  into the combustion chamber  12  for combustion. 
   When the combustion begins, the temperature in the combustion chamber  12  is not increased significantly. The helical memory metal element  73  does not substantially shrink. The helical memory metal element  74  does not substantially expand. The gap between the bead  78  and the membrane  50  is at its substantially maximum value. Thus, fuel can flow through this gap at a substantially maximum rate. 
   Referring to  FIG. 10 , when the combustion continues in the combustion chamber  12  for some time, the temperature increases in the chamber  12 . The helical memory metal element  73  shrinks while the helical memory metal element  74  expands. The rod  72  is lifted so that the gap between the head  78  and the membrane  50  is reduced. Thus, fuel flows through this gap at a reduced rate, and the combustion goes at a reduced scale. 
   The present invention has been described through illustration of some embodiments thereof. After a study of this specification, those skilled in the art can derive various variations from the embodiments. Therefore, the embodiments are only taken as examples and shall not limit the scope of the present invention that is defined in the following claims.