Patent Publication Number: US-6663383-B2

Title: Utility lighter with a safeguard

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a fuel-gas lighter—more particularly a utility lighter with a safeguard. 
     2. Description of Prior Art 
     Utility lighters are used for inflaming barbeque grills, fireplaces, candles, and other firing fields in daily life. Such a lighter, as shown in FIG.  5  and FIG. 6, is comprised of a gas container  4 , a shell  2 , and a long rod-like tube  3  for inflaming objects in hard-to-reach places. The gas container  4  contains highly compressed inflammable gas. Fuel lever  6  controls the opening and closing of gas container  4 &#39;s outlet. The friction force generated by pressing down trigger  8  activates piezoelectric unit  7  that is located on the inside of shell  2 , and releases the fuel to inflame the lighter. 
     When the user presses said trigger  8  with his finger, it contacts said lever  6 , lifting the valve to emit the gas from container  4  to the end of tube  3 . The pressing motion also activates the piezoelectric unit, generating a spark at the outside tip of barrel portion  3 , which in turn creates the flame. 
     Although this utility lighter conveniently inflames objects in hard-to-reach places by keeping the user&#39;s hand and face away from the flame, its gun-like shape promotes unsafe behavior in children who may mistake the lighter for a toy. Such behaviors may lead to fires and burn injuries. To prevent the utility lighter from being activated inadvertently by children, many lighters in the market are now equipped with a trigger-locking device. 
     A conventional utility lighter, such as that shown in FIG. 7, has a sliding switch  20  mounted on the handle&#39;s side. When the switch  20  is set to the “On” position, the switch&#39;s stopper withdraws from trigger  8 , allowing it to slide freely. Conversely, when the switch  20  is set to the “Off” position, the switch&#39;s stopper blocks trigger  8 , preventing the steps necessary to create a flame. Unfortunately, the users of lighters with safety functions designed in this way often forget to set switch to the “Off” position after using, defeating the purpose of the mechanism. 
     OBJECTS OF THE INVENTION 
     It is, therefore, a main object of the present invention to provide a lighter with an automatic safeguard so that inadvertent activation by children can be prevented. 
     The utility lighter of the present invention has a safeguard, which is comprised of a shell with a barrel portion, a gas container, a piezoelectric unit, and a safety device comprised of a trigger and a safety button. The piezoelectric unit is placed between a holding plate of the trigger and a blocking plate of the safety button that is backed by a compression spring. A locating plate is built on the shell to coordinate with the position of the safety button. 
     The piezoelectric unit has a sliding portion equipped with a hammer backed by a compression spring that is loaded inside the unit. The sliding portion travels the pre-set striking distance needed to hit the piezocrystal placed inside the unit for producing a spark. 
     The distance between the trigger&#39;s original position and the trigger&#39;s pressed position, called the trigger&#39;s travel distance, should be equal or greater than the striking distance of the sliding portion of the piezoelectric unit in order to generate a spark. Conversely, the travel distance should be lesser than the sum of the striking distance of the piezoelectric unit and the travel distance of the safety button in order to create the safeguard. 
     The said safety button has a blocking plate that extends inside the shell blocking the bottom end of the piezoelectric unit. A portion of the safety button extends out of the shell to form a button to be pressed by the user&#39;s thumb. 
     A locating plate is built inside the shell, opposite the backside of the safety button&#39;s blocking plate. A compression spring connects the two plates and holds the blocking plate upright. The elasticity of this compression spring should be less than that of the compression spring built on the inside of the piezoelectric unit. 
     The trigger has a holding plate at one end that extends inside the shell, holding the end of the sliding portion of the piezoelectric unit at the back-end, opposite the blocking plate of the safety button. The other end of the trigger extends to engage with the fuel lever. 
     SUMMARY OF THE INVENTION 
     A safety button is added to the common utility lighter, and a piezoelectric unit is placed between the trigger and the safety button, so it can move following the trigger action. The movement of the piezoelectric unit can be blocked or allowed, depending on whether or not the safety button is retained at its original position. When the user presses the safety button at the external of the lighter and sustains it at original position, the piezoelectric unit is blocked, and a spark is generated. If the safety button is free, the piezoelectric unit is allowed to slide backward so the trigger is unable to strike it, preventing the generation of the spark. Children will find it difficult to figure that the safety button need be pressed and sustained to create a flame. Therefore, such a lighter would greatly reduce fire damage or injury caused by a child&#39;s inadvertent activation. At the same time, an adult can use it without significant inconvenience. The structure of such a utility lighter would be simple enough to be easily manufactured. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a cross-section view of the present invention; 
     FIG. 2 is a cross-section view showing operation state of the present invention (with the safety button retained); 
     FIG. 3 is a cross-section view showing safeguard state of the safety button; 
     FIG. 4 is a cross section view of another embodiment of the present invention; 
     FIG. 5 is a solid view of a prior art; 
     FIG. 6 is a cross-section view of the prior art; and 
     FIG. 7 is a part exploded view of a prior art; 
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
     Referring to FIG. 1, a utility lighter with a safeguard is comprised of a shell  2  including a barrel portion  3 , a gas container  4 , a piezoelectric unit  7 , and a safety device that includes a trigger  8  and a safety button  100 . Shell  2  houses gas container  4 , and has a locating plate  210  that coordinates with safety button  100 . A sliding rail portion  220  is located on the top so that the safety button can be mounted and moved along it. 
     Piezoelectric unit has a sliding portion  9  equipped with a hammer backed by a compression spring loaded inside the unit. The sliding portion  9  travels the pre-set striking distance needed to hit the piezocrystal placed inside the unit for producing a spark. 
     Safety button  100  has an inner portion that is placed on the inside of shell  2 . 
     This portion houses a blocking plate  110  that blocks the bottom end of the piezoelectric unit  7 . An external portion, pressing portion  130 , is exposed outside the shell. Its teeth or indented surface provides a firm grip for the thumb. 
     A holding plate  800  is built at one end of trigger  8 . It extends inside shell  2 , which holds the end of the sliding portion  9  of the piezoelectric unit  7 . An extending portion  810  is built on the other end of trigger  8 . This portion engages with fuel lever  6  inside shell  2 . 
     The movable piezoelectric unit  7  is placed between holding plate  800  of trigger  8  and blocking plate  110  of the safety button  100 . A compression spring  200  is placed between locating plate  210  of the shell  2  and the backside of blocking plate  110  of the safety button  100 . The spring  200  pushes blocking plate  110  forward to tightly sandwich piezoelectric unit u with holding plate  800  of the trigger  8 . The elasticity of the said compression spring  200  is less than that of the compression spring loaded on the inside of the piezoelectric unit  7 . 
     Referring to FIG. 2, the user presses the thumb-pressing portion  130  of the safety button  100  with his thumb, simultaneously pulling the trigger  8  with his index finger. This movement engages extending portion  810  with fuel lever  6 , opening outlet  5  of gas container  4  and sending the gas to the end of the barrel  3 . Because the safety button  100  is retained at its original position, the sliding portion  9  of the piezoelectric unit  7  is pressed in by the holding plate  800  of the trigger  8 . As the sliding portion  9  of the unit  7  travels down its pre-set striking distance, the piezocrystal portion of the unit  7  is hit by the hammer loaded inside the unit  7 , generating the spark needed at the tip end of the barrel  3  to inflame the gas. 
     The travel distance of trigger  8  is equal to or greater than the striking distance of the sliding portion  9  of the piezoelectric unit  7 , but smaller than the sum of the striking distance of piezoelectric unit  7  and the travel distance of safety button  100 . 
     Referring to FIG. 3, when safety button  100  is not held in or up, holding plate  800  of trigger  8  will push the piezoelectric unit  7  backward along with safety button  100  and compression spring  200 . Because trigger  8  slides only for a certain distance, it stops before the sliding portion  9  of the piezoelectric  7  is sufficiently compressed to hit the piezocrystal portion of the unit  7 . 
     A child may have difficulty pulling the trigger  8  with his index finger while retaining the safety button  100  at its original position with his thumb. 
     Referring to FIG. 4, another embodiment of the present invention is shown in which the positions of trigger  8  and safety button  100  are exchanged. In this structure, the user must push the trigger  8  forward with his thumb while retaining the safety button  100  with his index finger.