Abstract:
A utility lighter includes a trigger adapted to simultaneously engage a fuel valve and piezo-electric element. A safety mechanism engages the trigger to prevent inadvertent ignition of the lighter or use of the lighter by a small child. The safety mechanism physically restricts movement of the trigger when engaged. The safety mechanism may be disengaged to allow the trigger to be activated. The safety mechanism may be released without extinguishing the flame and is re-engaged when the trigger is released.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     1. Field of the Invention  
         [0002]     The present invention relates to utility lighters, more particularly to utility lighters with safety mechanisms to prevent inadvertent ignition or ignition by a small child.  
         [0003]     2. Description of the Prior Art  
         [0004]     Utility lighters, i.e., lighters with an extension to separate the burner and the handle, have become ubiquitous in the modern household for a variety of reasons. The extension allows a user to safely and easily ignite a flame in otherwise difficult to reach areas, such as barbeque grills, pilot lights on gas appliances, and fire places. Moreover, the distance between the handle and the burner allows the lighter to be kept aflame for extended periods of time without burning the user—thus permitting the user to light, quickly and easily, a large number of candles, ignite several points in a pile of kindling, or otherwise maintain a flame as desired.  
         [0005]     Despite their convenience, utility lighters, as with any flame producing device, can be unsafe if inadvertently ignited or operated by a small child. Consequently, many safety mechanisms have been developed to prevent inadvertent ignition of and/or to make it difficult for a small child to operate utility lighters. Typically such safety mechanisms comprise a combination of two switches or triggers that must be operated simultaneously or in sequence before the lighter can be ignited. In most cases, a safety switch is engaged by the user&#39;s thumb and a trigger is pulled by the user&#39;s index finger. The coordination required to ignite the lighter significantly reduces or eliminates the possibility of inadvertent or accidental ignition. Likewise, the required coordination is typically too complex for a small child, essentially rendering the lighter inoperable in a small child&#39;s hands.  
         [0006]     For example, U.S. Pat. No. 6,318,992 to Sung (“Sung”) discloses a utility lighter having a safety switch that must be engaged before the trigger on the device may be activated to ignite the burner. When engaged, the safety switch of Sung simultaneously opens the outlet valve of a pressurized fuel container and disengages a lever that would otherwise block the travel of the trigger. When the fuel valve is opened, fuel travels through a tube to the burner. The user may then activate the trigger, which compresses a piezo-electric element that in turn generates an electrical charge. The electrical charge is discharged as a spark in the vicinity of the burner, thereby igniting the gas to generate the desired flame. One drawback of the Sung device is that unburnt fuel may be vented to the atmosphere merely by activating the safety switch (which opens the fuel valve), thus creating a potential safety hazard and wasting fuel. In other words, because the igniting spark is generated only when the trigger is activated, failure to pull the trigger once the safety switch is activated will result in fuel flowing through the burner and into the atmosphere. Another drawback of the Sung device is that the release of the safety switch will cut off the flow of fuel to the burner, thus extinguishing the flame. As a result, if the user wishes to maintain a flame for any length of time, the user must keep the safety switch engaged. As the safety switch is typically engaged by the user&#39;s thumb, preserving this position over the desired period of time may become uncomfortable or difficult.  
         [0007]     In another example, U.S. Pat. No. 6,663,383 to Jon (“Jon”) discloses a utility lighter having a safety switch that must be engaged before the trigger on the device may be activated to ignite the burner. Unlike the Sung device, the trigger of the Jon device simultaneously activates a fuel valve and triggers a piezo-electric igniter. However, the safety switch operates by holding a blocking plate in place against one side of the piezo-electric igniter. Consequently, if the safety switch is not held in place by the user, the igniter cannot be compressed and no ignition will occur. Nonetheless, the trigger may still be activated, thus opening the fuel valve. Thus, similar to the Sung device, merely activating the trigger of the Jon device, without holding the safety switch in place, will allow un-burnt fuel to be vented to the atmosphere, creating a safety hazard and wasting fuel. Unlike the Sung device, however, the Jon device does allow the user to release the safety switch after ignition while still keeping the fuel valve open with the trigger which, because it is activated by the index finger, is more ergonomically efficient and thus more comfortable to the user.  
         [0008]     U.S. Pat. No. 6,722,877 to Wang et al. (“Wang”) also discloses a utility lighter having a safety switch that must be engaged before the trigger on the device may be activated to ignite the burner. However, unlike the Sung device, the safety switch of the Wang device repositions an actuating member within the lighter—when the safety switch is depressed, activation of a trigger causes the actuating member to engage both a fuel valve and a piezo-electric igniter simultaneously. Consequently, fuel cannot be vented without being ignited, thus avoiding the waste and hazard associated with the venting of unburnt fuel. However, the use of an intervening actuating member increases the mechanical complexity of the lighter, thus increasing the complexity of manufacture and the possibility of component failure. In addition, the actuating member of the Wang device must slide across the base of the safety switch for the lighter to operate. The friction arising from this interaction can make the lighter undesirably difficult to operate or, conversely, require the use of components manufactured to higher tolerances to reduce friction. Furthermore, if the safety switch of the Wang device is released during use, the actuating member returns to the safety position, thereby closing the fuel valve and extinguishing the flame. Thus, like the Sung device, the safety switch must remain engaged if the flame is to be maintained. Because the safety switch is oriented such that it is activated by the thumb, maintaining the safety switch in the activated position may be uncomfortable to the user over prolonged periods of time.  
         [0009]     Accordingly, it would be desirable to provide a safety mechanism for a utility lighter that prevents inadvertent ignition. It also would be desirable to provide a safety mechanism for a utility lighter that renders the lighter difficult or impossible for a small child to operate. It also would be desirable to provide a safety mechanism for a utility lighter that prevents the venting of unburnt fuel to the atmosphere. It also would be desirable to provide a safety mechanism for a utility lighter that is ergonomically efficient, allowing a user to maintain a flame for a prolonged period of time with little or no physical discomfort. It would also be desirable to provide a safety mechanism for a utility lighter that is simple to manufacture and reliable in use.  
       SUMMARY OF THE INVENTION  
       [0010]     A utility lighter according to the present invention includes a housing and a fuel container disposed within the housing. A fuel lever is affixed within the housing and engages a fuel valve to allow fuel to be delivered from the fuel container to a burner. A piezo-electric element is affixed within the housing and a trigger, which is slidably mounted to the housing, is adapted to simultaneously engage the fuel lever and the piezo-electric element.  
         [0011]     A safety mechanism is provided to prevent the inadvertent ignition of the lighter or operation of the lighter by a small child. The safety mechanism includes a safety switch slidably mounted on the housing and a safety lever pivotally disposed within the housing. The safety lever is positioned between and adapted to engage the safety switch and selectively engage the trigger. Thus, in order to operate the trigger (thereby opening the fuel valve and generating a spark from the piezo-electric element), the safety switch must first be released. In addition, the safety lever is adapted to allow the safety switch to be released without extinguishing the flame, thus allowing a flame to be comfortably maintained by the user so long as the trigger is held in the engaged position.  
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0012]      FIG. 1  shows a cross-sectional side view of a utility lighter according to the present invention.  
         [0013]      FIG. 2  shows a partial cross-sectional side view of the trigger mechanism of the utility lighter of  FIG. 1  in a first operational state.  
         [0014]      FIG. 3  shows a partial cross-sectional side view of the trigger mechanism of the utility lighter of  FIG. 1  in a second operational state.  
         [0015]      FIG. 4  shows a partial cross-sectional side view of the trigger mechanism of the utility lighter of  FIG. 1  in a third operational state.  
         [0016]      FIG. 5  shows a cross-sectional side view of an alternate embodiment of a utility lighter according to the present invention.  
         [0017]      FIG. 6  shows a partial cross-sectional side view of the trigger mechanism of the utility lighter of  FIG. 5  in a first operational state.  
         [0018]      FIG. 7  shows a partial cross-sectional side view of the trigger mechanism of the utility lighter of  FIG. 5  in a second operational state.  
         [0019]      FIG. 8  shows a partial cross-sectional side view of the trigger mechanism of the utility lighter of  FIG. 5  in a third operational state.  
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0020]     Referring to  FIGS. 1-4 , a utility lighter  10  according to the present invention comprises a housing  12  and a lighter tube  14 . The housing  12  contains a trigger  24 , a safety switch  26 , a fuel container  28 , a fuel valve  30 , a piezo-electric element  32 , a safety latch  34 , and a fuel lever  36 . The lighter tube  14  contains an ignition mechanism  16 , a burner  18 , a gas flow tube  20  and ignition wires  22 .  
         [0021]     Certain components of the lighter  10 , specifically the fuel container  28 , the fuel valve  30  and the piezo-electric element  32  are well-known in the art. Accordingly, those of ordinary skill in the art will recognize that such components may be selected as desired and suited for the particular design to be employed in the practice of the present invention. Other components of the lighter  10 , such as the housing  12 , the trigger  24 , the safety switch  26 , the safety latch  34 , and the fuel lever  36  are preferably fabricated with a material having sufficient stiffness to permit operation of the lighter  10  without undue flexure. Suitable materials are familiar to those of ordinary skill in the art and may be selected accordingly.  
         [0022]     The housing  12  may be formed to provide a “pistol”-like form or any other ergonomically desirable shape. The housing  12  includes a stop  38  to position and support the piezo-electric element  32 , and a safety latch pivot  42  to engage the safety latch  34 . The internal features may be integrally formed from the material of the housing  12  or otherwise affixed within the housing.  
         [0023]     Referring to  FIG. 4 , the trigger  24  is positioned within the housing  12  so as to allow the trigger  24  to slide back and forth within the housing  12 , as indicated by arrow  60 .  
         [0024]     The piezo-electric element  32  is positioned and secured within the housing  12  and between the stop  38  and the trigger  24 . The piezo-electric element  32  is positioned such that when the trigger  24  is pulled or drawn towards the peizo-electric element  32  in the direction indicated by arrow  60 , the piezo-electric element  32  is sandwiched between the stop  38  and the trigger  24 , thereby activating the spring-loaded mechanism of the piezo-electric element  32 . Upon activation, the piezo-electric element  32  generates a brief high-voltage electrical charge that is discharged through the ignition wires  22  and to the ignition mechanism  16  at the burner  18 . When the trigger  24  is released, the spring-loaded mechanism of the piezo-electric element  32  urges the trigger  24  into its original position.  
         [0025]     The fuel container  28  is positioned and secured within the housing  12 . The fuel valve  30  is affixed to the fuel container  28  such that it is positioned proximate to the trigger  24 . The fuel valve  30  may include a flame height adjuster  31 , which may be rotated by means of an adjustment lever  33  to allow the user to vary the flow of fuel emanating from the lighter  10  and, hence, the intensity of the flame provided by the lighter  10 .  
         [0026]     The fuel lever  36  is positioned so as to engage the fuel valve  30  and the trigger  24 , such that when the trigger  24  is pulled in the direction indicated by arrow  60 , the lever  36  rotates as indicated by arrows  66 A and  66 B, pulling the fuel valve  30  forward (i.e., in the opposite direction of the motion of the trigger  24 ), and opening the valve  30 . Upon opening of the valve  30 , fuel flows through the gas flow tube  20  to the burner  18 .  
         [0027]     Thus, it can be seen that activation of the trigger  24  acts to simultaneously open the fuel valve  30  and operate the piezo-electric element  32 . In this manner, fuel is released only in the presence of the spark generated by the piezo-electric element  32 , ensuring that the fuel will be ignited and substantially reducing or eliminating the risk of venting unburnt fuel to the atmosphere. Moreover, when the trigger  24  is released, the trigger  24  is urged back into the “off” position by the piezo-electric element  32 , as described above, which also has the effect of closing the fuel valve  30 .  
         [0028]     Referring to  FIGS. 2 and 3 , the safety switch  26  is positioned on and protrudes through the housing  12 . The safety switch  26  is preferably located proximate to and on the opposite side of the lighter  10  from the trigger  24  to allow the user&#39;s thumb to be used to activate the safety switch  26  (by urging the switch  26  in the direction indicated by arrow  62 ) prior to or simultaneously activating the trigger  24  with the index finger. A spring  27  is positioned within the safety switch  26  and engages the housing  12  to urge the safety switch  26  back into its original position when released.  
         [0029]     The safety latch  34  is positioned within the housing  12  and is mounted on the safety lever pivot  42 . A spring  44  biases the latch  34  in the desired position locked position. The latch  34  is positioned to engage the safety switch  26  and the trigger  24  such that when the safety switch  26  is engaged by the user in the direction indicated by arrow  62 , the latch  34  is rotated about the pivot  42  in the direction indicated by arrow  64  and disengaged from the trigger  24 , thereby allowing the trigger  24  to be operated in the manner described above. When the safety switch  26  is not engaged, the spring  44  biases the latch  34  such that the latch is rotated downward into the trigger  24  and a catch  48  on the latch  34  engages a corresponding catch  49  on the trigger  24 , fixing the trigger  24  in place. In short, release of the safety latch  34  acts only to release the trigger  24  and does not open fuel valve  30  or activate piezoelectric element  32 . Thus, unlike safety mechanisms of the prior art, activation of the safety switch of the present invention does not permit the release of unburnt fuel. Moreover, because the activation of the trigger  24  (which is only possible when the safety switch  26  has been activated) simultaneously opens the fuel valve  30  and triggers the piezo-electric element  32 , igniting the flame, the flame is ignited by the activation of the trigger, preventing the release of unburnt gas.  
         [0030]     In addition, the safety switch  26  may be released once the flame is ignited without extinguishing the flame. This is because the release of the safety switch  26  releases the latch  34 , which is then urged against the top of the trigger  24  (as shown in ghosted lines in  FIG. 4 ) by the spring  44 . The latch  34  does not interfere with the flow of fuel or otherwise inhibit the flow of fuel. This allows the user to release the safety switch  26  and employ only the user&#39;s index finger to maintain a flame, a more comfortable and ergonomically efficient position for the user&#39;s hand. Once the trigger  24  is released, it is urged into the “off” position by the piezo-electric element  32 . As the trigger  24  returns to the “off” position, the latch  34  is urged against the trigger  24  and re-engages catch  49  to lock the trigger  24  in place.  
         [0031]     Referring to  FIGS. 5-8 , an alternative embodiment of a utility lighter  110  according to the present invention comprises a housing  112  and a lighter tube  114 . The housing  112  contains a trigger  124 , a safety switch  126 , a fuel container  128 , a fuel valve  130 , a piezo-electric element  132 , a safety latch  134 , and a fuel lever  136 . The lighter tube  114  contains an ignition mechanism  116 , a burner  118 , a gas flow tube  120  and ignition wires  122 .  
         [0032]     Certain components of the lighter  110 , specifically the fuel container  128 , the fuel valve  130  and the piezo-electric element  132  are well-known in the art. Accordingly, those of ordinary skill in the art will recognize that such components may be selected as desired and suited for the particular design to be employed in the practice of the present invention. Other components of the lighter  110 , such as the housing  112 , the trigger  124 , the safety switch  126 , the safety latch  134 , and the fuel lever  136  are preferably fabricated with a material having sufficient stiffness to permit operation of the lighter  110  without undue flexure. Suitable materials are familiar to those of ordinary skill in the art and may be selected accordingly.  
         [0033]     The housing  112  may be formed to provide a “pistol”-like form or any other ergonomically desirable shape. The housing  112  includes a stop  138  to position and support the piezo-electric element, a fuel lever pivot  140  to engage the fuel lever  136 , and a safety latch pivot  142  to engage the safety latch  134 . The internal features may be integrally formed from the material of the housing  112  or otherwise affixed within the housing.  
         [0034]     Referring to  FIG. 8 , the trigger  124  is positioned within in the housing  112  so as to allow the trigger  124  to slide back and forth within the housing  112 , as indicated by arrow  160 .  
         [0035]     The piezo-electric element  132  is positioned and secured within the housing  112  and between the stop  138  and the trigger  124 . The piezo-electric element  132  is positioned such that when the trigger  124  is pulled or drawn towards the piezo-electric element  132  in the direction indicated by arrow  160 , the piezo-electric element  132  is sandwiched between the stop  138  and the trigger  124 , thereby activating the spring-loaded mechanism of the piezo-electric element  132 . Upon activation, the piezo-electric element generates a brief high-voltage electrical charge that is discharged through the ignition wires  122  and to the ignition mechanism  116  at the burner  118 . When the trigger  124  is released, the spring-loaded mechanism of the piezo-electric element  132  urges the trigger  124  into its original position.  
         [0036]     The fuel container  128  is positioned and secured within the housing  112 . The fuel valve  130  is affixed to the fuel container  128  such that it is positioned proximate to the trigger  124 . The fuel valve  130  may include a flame height adjuster  131 , which may be rotated by means of an adjustment lever  133  to allow the user to vary the flow of fuel emanating from the lighter  110  and, hence, the intensity of the flame provided by the lighter  110 . The fuel lever  136  is positioned so as to engage the fuel valve  130 , the fuel lever pivot  140 , and the trigger  124 , such that when the trigger  124  is pulled in the direction indicated by arrow  160 , the lever  136  rotates around the pivot  140  as indicated by arrows  166 A and  166 B, pulling the fuel valve  130  forward (i.e., in the opposite direction of the motion of the trigger  124 ), and opening the valve  130 . Upon opening of the valve  130 , fuel flows through the gas flow tube  120  to the burner  118 . Notably, the fuel lever  136  may comprise a yoke-shaped lever straddling the piezo-electric element  132 . In this manner, the fuel lever  136  may contact and engage the trigger  124  in a region proximate to where the piezo-electric element  132  engages the trigger. Consequently, the force required to activate the trigger  124  and ignite lighter  110  may be concentrated in the same region of the trigger. It has been found that this arrangement permits the trigger  124  to be operated smoothly and efficiently with little excess effort or discomfort to the user.  
         [0037]     Thus, it can be seen that activation of the trigger  124  acts to simultaneously open the fuel valve  130  and operate the piezo-electric element  132 . In this manner, fuel is released only in the presence of the spark generated by the piezo-electric element  132 , ensuring that the fuel will be ignited and substantially reducing or eliminating the risk of venting unburnt fuel to the atmosphere.  
         [0038]     Referring to  FIGS. 6 and 7 , the safety switch  126  is positioned on and protrudes through the housing  112 . The safety switch  126  is preferably located proximate to and on the opposite side of the lighter  110  from the trigger  124  to allow the user&#39;s thumb to be used to activate the safety switch  126  (by urging the switch  126  in the direction indicated by arrow  162 ) prior to or simultaneously activating the trigger  124  with the index finger. A spring  127  is positioned within the safety switch  126  and engages the housing  112  to urge the safety switch  126  back into its original position when released.  
         [0039]     The safety latch  134  is positioned within the housing  112  and is mounted on the safety lever pivot  142 . A spring  144  biases the latch  134  in the desired position locked position. The latch  134  is positioned to engage the safety switch  126  and the trigger  124  such that when the safety switch  126  is engaged by the user in the direction indicated by arrow  162 , the latch  134  is rotated about the pivot  142  in the direction indicated by arrow  164  and disengaged from the trigger  124 , thereby allowing the trigger  124  to be operated in the manner described above. When the safety switch  126  is not engaged, the spring  144  biases the latch  134  such that the latch is rotated downward into the trigger  124  and a catch  148  on the latch  134  engages a corresponding catch  149  on the trigger  124 , fixing the trigger  124  in place. In short, release of the safety latch  134  acts only to release the trigger  124  and does not open fuel valve  130  or activate piezo-electric element  132 . Thus, unlike safety mechanisms of the prior art, activation of the safety switch of the present invention does not permit the release of unburnt fuel. Moreover, because the activation of the trigger  124  (which is only possible when the safety switch  126  has been activated) simultaneously opens the fuel valve  130  and triggers the piezo-electric element  132 , igniting the flame, the flame is ignited by the activation of the trigger, preventing the release of unburnt gas.  
         [0040]     In addition, the safety switch  126  may be released once the flame is ignited without extinguishing the flame. This is because the release of the safety switch  126  releases the latch  134 , which is then urged against the top of the trigger  124  (as shown in ghosted lines in  FIG. 8 ) by the spring  144 . The latch  134  does not interfere with the flow of fuel or otherwise inhibit the flow of fuel. This allows the user to release the safety switch  126  and employ only the user&#39;s index finger to maintain a flame, a more comfortable and ergonomically efficient position for the user&#39;s hand. Once the trigger  124  is released, it is urged into the “off” position by the piezo-electric element  132 . As the trigger  124  returns to the “off” position, the latch  134  is urged against the trigger  124  and re-engages catch  149  to lock the trigger  124  in place.  
         [0041]     It is also to be appreciated that the foregoing description of the invention has been presented for purposes of illustration and explanation and is not intended to limit the invention to the precise manner of practice herein. It is to be appreciated therefore, that changes may be made by those skilled in the art without departing from the spirit of the invention and that the scope of the invention should be interpreted with respect to the following claims.