Patent Publication Number: US-2004058289-A1

Title: Lighter with child resistant shielded sparkwheel ignition mechanism

Description:
BACKGROUND OF THE INVENTION  
       [0001] 1. Field of the Invention  
       [0002] The present invention relates to a child resistant ignition mechanism for a lighter that makes sparks by rotating a sparkwheel against a flint, and in particular to an ignition mechanism having thumbwheels that shield the sparkwheel from direct actuation and require large downward forces be applied by the user to operatively connect them to the sparkwheel.  
       [0003] 2. Description of the Related Art  
       [0004] Some prior art ignition mechanisms have thumbwheels which are separated from the sparkwheel, requiring additional force in a predetermined direction to engage the thumbwheels with the sparkwheels. If properly designed, this increases the difficulty of creating ignition sparks enough so that someone without the intellectual capacity to appreciate the danger of an open flame, cannot produce a flame.  
       [0005] Ignition mechanisms for gas lighters are disclosed in U.S. Pat. Nos. 5,547,370, 5,759,023, 5,868,561, 5,913,674, 5,971,749, 5,997,281, 6,053,727, and 6,074,198. These systems comprise ignition mechanisms in which two faces, one of the thumbwheel and one of the sparkwheel, are pushed together while the thumbwheel is rotated. When enough force is applied between the thumbwheel and sparkwheel, any rotation of the thumbwheel is coupled to the sparkwheel, which rubs against a flint to generate a shower of sparks. If gas is released when the shower of sparks is present, ignition takes place. Various thumbwheel and sparkwheel engagement mechanisms have been proposed. Further, a system that controls the rotation of a thumbwheel and the engagement of a thumbwheel and a sparkwheel by an elastic member is disclosed in U.S. Pat. No. 5,104,313.  
       [0006] For about a decade U.S. Government regulations have required that inexpensive cigarette lighters whether refillable or disposable, have features that make the production of a flame difficult for small children. Ideally, these lighters would be difficult to operate for someone without the intellectual capability to understand and appreciate the danger of an open flame, but are easily operated by adults. Experience has shown that precocious children can occasionally produce a flame with intellectually challenging child resistant lighters, especially when the operation of the lighter is demonstrated to them on a daily basis by their parents, and when those lighters are thereafter carelessly left where children can experiment with them endlessly.  
       [0007] To determine whether or not a particular lighter has sufficient resistance to operation by a child, objective tests utilizing surrogate lighters are used with children fifty one months old or younger to assure that very few children in that age group can operate the surrogate lighter in a fashion that would produce a flame in the equivalent lighter being sold in the United States. Since the intellectual capability of all children in the target age group is a very difficult characteristic to design against, in fact, child resistant lighters in the United States tend to be a combine trickiness of operation and difficulty of operation by someone who has limited manual dexterity, limited strength, and/or small hands and fingers.  
       [0008] There are places in the world that are progressing from subsistence farming economies, where simple items, such as cigarette lighters, can be assembled at extremely low cost by hand. Such low labor costs enable a manufactured cost that is about half of the cost that can be achieved by automation in industrialized countries with higher labor costs. Therefore, it has become critical to those selling lighters in the United States to design child resistant lighters, which can be manufactured very economically, by hand.  
       [0009] Summarizing, a particular lighter design must be economical to manufacture and child resistant. Yet, it must be manufacturable in prototype quantities and tested prior to importation as a production model into the United States. This process takes somewhere between six months and a year. Therefore, many individuals and companies have filed patent applications, some with relatively broad claims, prior to the time that they have determined that the child resistancy of the lighter being patented is sufficient to pass U.S. Government regulations. Now, if someone wishes to improve one or more aspects of a lighter, not only must the lighter be designed for extremely economical manufacture, it must avoid the claims of patents on lighters, which although not sufficiently child resistant to be allowed into the United States, cannot be improved by others to provide the required child resistancy, because of the broad claims in of one or more unexpired patents.  
       [0010] Examples include Zellweger, U.S. Pat. No. 5,096,414, wherein child resistancy is provided by disconnected thumbwheels on either side of the sparkwheel of a sparkwheel lighter. The patent indicates that an adult thumb has enough flesh to operate the sparkwheel directly, whereas a child&#39;s thumb does not, even though presumably a child&#39;s thumb is thinner and might fit between the two thumbwheels if stroked front to back rather than across the thumbwheels. Lighters, whose primary actuation method is a force sensitive slipable mechanism between the sparkwheel and the thumbwheels such as those shown in U.S. Pat. No. 5,547,370 which employs a polygonal thumbwheel slip mechanism have been enjoined from sales in the Unites States by the owner of the Zellweger patent because it is possible for the flesh of an adult thumb to actually contact and assist in the rotation of the sparkwheel.  
       [0011] Therefore, there has been a need to provide a non-infringing spark wheel lighter, which can be economically manufactured and assembled essentially by hand and at the same time provide the required child resistancy.  
       SUMMARY OF THE INVENTION  
       [0012] The present ignition mechanism for a gas lighter solves the aforementioned problems and makes sparks when a sparkwheel is rotated against a flint. The present ignition mechanism includes two axle support members mounted to the body of the lighter between which an axle extends. A sparkwheel and two inwardly flanged thumbwheels are loosely mounted on the axle, the sparkwheel is loosely mounted for ease of manual assembly while the thumbwheels are loosely mounted to provide child resistancy, as will be explained. The axle support members retain stub portions of the axle in bearings so that the axle rotates about a fixed line with respect to the flint. Therefore to cause the sparkwheel to rotate with respect to the flint to produce sparks, requires that the axle be turned. The cross-sectional shape of the axle where the sparkwheel in mounted thereon, only needs to be shaped with respect to a hole through the sparkwheel so that relative rotational motion is not possible. This can also be accomplished by pinning or keying the axle and sparkwheel together or through the use of adhesive, although the former increases cost and the latter may produce a failure point that makes the lighter inoperative.  
       [0013] The axle shape where the thumbwheels are mounted is preferably rotationally non-round symmetrical, with a polygon shape being preferred. The thumbwheels have center holes that are complementary to the axle cross-sectional shape, but of a size large enough to turn with respect thereto, even when the thumbwheels are tilted with respect to the axis of the axle. The inward flange on each thumbwheel forms the thumb engagement outer circumferential surface therefor. For the user to engage the thumbwheels with the axle, a substantial inward radial force must be applied between the user&#39;s thumb and the flange. Since the engagement force between the thumbwheels and the axle acts a distance spaced from the sparkwheel and outside the thumb force applied to the flange, the thumbwheels tilt toward each other, over the sparkwheel, preventing the thumb from engaging the sparkwheel to allow direct rotation thereof. Children of an age where they do not appreciate the danger of fire, have difficulty producing enough radially inward force to engage the thumbwheels with the axle, and at the same time producing the circumferential force required to rotate the axle and sparkwheel to produce gas igniting sparks. This difficulty of operation is partly because the thumbwheels easily turn with respect to the axle, so the action necessary to engage the thumbwheels with the axle is not obvious to the child, and partly because children are unlikely to have enough strength to accomplish spark production.  
       [0014] The complementary shapes of the axle and thumbwheels can be changed both in relative size and shape and the clearance can be changed to allow more or less tilting of the thumbwheels. In addition, the strength of the flint springs can be changed to produce a balance where most adults can operate the lighter, but few, if any, children under the age of fifty one months can operate it even if parents carelessly demonstrate proper operation and leave multiple examples where a child can experiment with the lighter many times.  
       [0015] The gas igniting sparks are produced in the vicinity of the gas release nozzle. The gas is released when the nozzle is lifted by a rocking gas release lever. The construction of nozzles is such that it is preferable that they are lifted in a straight line, but the more normal pivoting gas release lever tries to move the nozzle along a circular path. Therefore, the present lever is formed with a pair of centrally positioned rockers which rock and slide on suitable surfaces on the top of the lighter body so the nozzle can move in a linear path with the lever moving end to end to compensate for the angular differences between the nozzle and the gas release lever as it is operated.  
       [0016] Therefore, an object of the present invention is to provide a child resistant ignition system which is versatile so that it can pass child resistancy testing in many countries.  
       [0017] Another object is to provide a child resistant ignition system that can be assembled in an automated factory, a partly automated factory or manually, so that it can be produced at competitive prices, no matter how the costs of labor vary throughout the world.  
       [0018] Another object is to provide a child resistant ignition system that avoids infringement of U.S. patents broadly claiming child resistant features, even if those claimed features may not pass child resistance testing in the United States.  
       [0019] Another object is to provide a child resistant ignition system which is easily operated by those with the intellectual capacity to appreciate the danger of an open flame.  
       [0020] These and other objects and advantages of the present invention will become apparent to those skilled in the art after considering the following detailed specification, together with the accompanying drawings wherein: 
     
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
     [0021]FIG. 1 is a partial cross-sectional side elevational view of a gas lighter having the ignition mechanism of the present invention in the non-operating state;  
     [0022]FIG. 2 is a detail cross-sectional side view of the sparkwheel, a flint with its spring mounted on a polygonal axle and also showing one of the thurnbwheels of the lighter of FIG. 1;  
     [0023]FIG. 3 is a partial cross-sectional front view of the spark ignition assembly for the lighter of FIG. 1 as it is being actuated by a thumb;  
     [0024]FIG. 4 is a detail cross-sectional side view of a thumbwheel mounted on the polygonal axle of the lighter of FIG. 1;  
     [0025]FIG. 5 is a detail cross-sectional side view of a modified thumbwheel mounted on the polygonal axle of the lighter of FIG. 1;  
     [0026]FIG. 6 is an enlarged cross-sectional view of the thumbwheel for loose mounting on the polygonal axle of the lighter of FIG. 1;  
     [0027]FIG. 7 is a side detail view of the gas release lever and gas release nozzle of the lighter of FIG. 1; and  
     [0028]FIG. 8 is a motion diagram of the gas release lever of FIG. 1 showing its rocking and sliding movement.  
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT  
     [0029] The following is a description explaining in detail preferred embodiments of the ignition mechanism according to the present invention. Referring to the drawings more particularly by reference numbers, the gas lighter  10  is equipped with a body  12  in which fuel gas is stored, and a nozzle  14 , through which fuel gas is released by the rocking of an operating lever  16 . The operating lever  16  includes one end  18  that engages the nozzle  14 , lifting it to release the gas when the opposite end  20  is depressed by the user&#39;s thumb. The gas is ignited by a shower of sparks generated by a child resistant ignition assembly  22 .  
     [0030] As shown in FIG. 2, the assembly  22  includes a flint  24 , which is pushed upward against a sparkwheel  26  by a spring  28 . The sparkwheel  26  has the configuration of a cylindrical file. Preferably, the sparkwheel  26  includes a non-round opening  30  there through so that it can be manually slid onto and thereby mounted on a non-round axle portion  32  of an axle  34 , shown as having a sextuple polygonal cross-sectional shape over most of its length. The axle  34  includes short round stubs  36  extending from the non-round portion  32  which are supported in bearing holes  38  formed in axle support members  40  and  41  extending upwardly from the body  12  of the lighter  10 . Therefore, the sparkwheel  26  and axle  34  rotate together.  
     [0031] As shown in FIGS. 3 and 4, two thumbwheels  42  and  44  are also mounted on the non-round portion  32  of the axle  34  with a matching non-round hole, such as the sextuple polygon hole  46  which is congruent to the axle portion  32 , but large enough to rotate there about unless enough downward force is applied to the thumbwheels  42  and  44  to cause them to engage the axle portion  32 . If at the same time radial force is applied to the thumbwheels  42  and  44 , the axle  34  and sparkwheel  26  rotate therewith to produce a shower of sparks.  
     [0032] As shown in FIG. 5, the thumbwheels  42  or  44  can include a hole  48  that is generally polygonal shaped with relieved corners  50  so the force required to engage the thumbwheels  42  or  44  with the axle  34  is relatively uniform as the assembly  22  rotates. The relieved corners  50 , shown with the modified thumbwheel  52 , also assist in allowing inward facing flanges  54  and  56  (FIG. 6) at the outer peripheries  58  and  60  of the thumbwheels  42  and  44  to lean inwardly in response to force (arrow  62 ) applied by the user&#39;s thumb  64  thereto. If the thumbwheels  42  and  44  did not tilt, the distance between the thumbwheels  42  and  44  could not be reduced below the diameter of the flint  24 . The tilting or leaning causes the flanges  54  and  56  to guard the sparkwheel  26  from being directly actuated by a thumb  64 . The distance  66  between the axle support members  40  and  41  between which the axle portion  32  extends, is larger than the width  67  of the sparkwheel  26  and the width  68  of disk portions  69  and  70  of the thumbwheels  42  and  44 . This provides clearance for the tilt caused because the average force (arrow  72  of FIG. 6) initially applied by the thumb  64  is inside the average reactive force (arrow  76 ) by enough distance (arrow  78 ) between the thumbwheel hole  48  and the axle portion  34  to cause tilting to reliability to occur whenever an ignition is attempted.  
     [0033] Therefore, ignition sparks are very difficult for a child to produce because not only must the child recognize that downward force must be applied to operatively engage the thumbwheels  42  and  44  with the sparkwheel  26 , the child must develop relatively large forces both inwardly and radially. Then the child must release gas by depressing the operating lever  16  before the sparks extinguish.  
     [0034] The nozzle  14  is designed for a linear pull to release gas. Therefore, a conventional pivoted lever whose ends follow circular paths tend to stress the nozzle  14 . In the present lighter  10 , instead of being restrained to pivot, the operating lever  16  includes a center section  80  as shown in FIG. 7 including a pair of rockers  82  and  83 , which engage a top surface  84  of the body  12 . An optional lever extension  85  can be provided which is loosely restrained in a cavity  86  in the lighter body  12  to stabilize the lever  16  from movement toward or away from the nozzle  14 . With a rocker type operating lever  16 , the motion of the nozzle  14  can be straight vertically  88  as shown in FIG. 8, which is a motion diagram of the lever  16 . Note that the end  20  follows a curved path  90  and the center section  80  slides  92  when it rotates  94 .  
     [0035] Thus there has been shown and described novel child resistant ignition systems for sparkwheel lighters, which fulfill all the objects and advantages sought therefor. Many changes, modifications, alterations and other uses and applications which do not depart from the spirit and scope of the invention are deemed to be covered by the invention which is limited only by the claims that follow: