Reduced resistence device for producing ignition sparks

An apparatus is disclosed for providing more uniform lighter spark wheel actuation. Uniform actuation is facilitated in the apparatus according to the invention by reducing the formation of deep grooves and high ridges in the flint. In one embodiment of the invention, a spark wheel coil formed from wire having at least one substantially flat side is utilized to reduce ridge formation. The spark wheel coil includes pitting in a transversal direction made on the outer surface of the coil. The pitting forms projections which protrude from the core of the coil and which, when contacting a pyrophoric flint while the coil spring is rotated about its axis, produce a tangential cutting across the pyrophoric flint to emit an ignition spark.

BACKGROUND OF THE INVENTION 
1. Technical Field 
The present invention relates to a lighter which consumes hydrocarbon fuel 
such as butane and includes a spark producing means Specifically, the 
present invention relates to an improved spark producing means for a 
lighter which is more uniformly operatable. 
2. Discussion of the Related Art 
A conventional cigarette lighter includes a body containing a fuel 
reservoir filled with a liquified and pressurized hydrocarbon fuel, a 
valve actuator lever, a spark wheel, a flint in frictional contact with 
the spark wheel, and a fuel flow control valve in fluid communication with 
the fuel reservoir. After the spark wheel is rotated against the flint by 
digital manipulation to produce sparks, the valve actuator lever is 
depressed allowing gaseous hydrocarbon fuel to flow out of the reservoir 
through the flow control valve. The sparks then ignite the released fuel 
to produce a flame. Such lighters are known in the art and are 
commercially available. 
Specific means for producing ignition sparks when contacting a pyrophoric 
flint in these lighters are also known in the art. For example, U.S. Pat. 
No. 4,509,916 to Le Boudec discloses a device for producing an ignition 
spark when contacting a flint. The device includes a flint cutting member 
made from helically-coiled wire with a circular cross section which 
includes saw-teeth projections for contacting and cutting the flint to 
create sparks. The flint, like the coiled wire, also includes a circular 
cross section. The device may be configured and adapted for use as a spark 
wheel in known lighters. 
However, these related art spark producing means are disadvantageous in 
that irregular friction is produced between the flint and the 
user-rotatable spark wheel. This irregular friction leads to non-uniform 
rotational force requirements for rotating the spark wheel, and thus may 
increase the difficulty in producing ignition sparks. 
More particularly, when a flint with a circular cross section is utilized 
in conjunction with a art spark wheel coil fashioned from wire with a 
circular cross section, the surface of the flint contacting the coil 
becomes deeply grooved over time so as to match the curved coil surface. 
The same difficulty can also arise with spark wheel assemblies having a 
flint cutting member made from a solid cylinder rather than coiled wire. 
Such solid cylinders are typically cut with a spiral groove on the outer 
surface to improve the spark creating characteristics of the part. This 
spiral groove in the cutting member can also result in a deeply grooved 
flint, such as encountered with the coiled wire cutting members. In 
addition, the rotation of such cutting members against the flint during 
use urges the flint to rotate about its central axis. 
These two factors, i.e., the deep grooving of the flint surface (and 
resulting high ridges) and the urged rotation of the flint during use, are 
disadvantageous in combination as they bring about non-uniform user 
actuation of the spark wheel. More specifically, the flint, with a highly 
ridged/deeply grooved striking surface as shown in FIG. 7A, provides a 
significant non-uniform resistance to rotation of the spark wheel assembly 
as the cutting member is required to periodically breakdown the high 
ridges as it is rotated. The nonuniformity of the force required to rotate 
the spark wheel assembly can be increased further when the flint itself 
rotates on its axis as a result of the screw thread like action of the 
cutting member on the flint. Such rotation of the flint is difficult for 
the user to overcome due to the high ridges on the flint surface which 
require a relatively high force to break through. 
Highly non-uniform resistance is especially disadvantageous in many of the 
newer child resistant lighters. For example, U.S. Pat. No. 5,483,978 to 
Doiron discloses a child resistant lighter with a guard which partially 
covers the spark wheel, thereby increasing the difficulty of rotating the 
same. This spark wheel cover, when combined with the non-uniform force 
requirements of the prior art spark producing means can result in 
non-uniform and unpredictable increases in the difficulty of lighter 
actuation by intended users. 
OBJECTIVES AND SUMMARY OF THE INVENTION 
In view of the above disadvantages of the related art, it is an object of 
the present invention to provide a spark producing means which facilitates 
smooth, uniform actuation by intended users. 
It is a further object of the invention to provide such a spark producing 
means that is relatively easy to manufacture and that requires minimal 
design modification. 
In accordance with the present invention, a flame producing lighter is 
provided which includes a lighter body containing a fuel reservoir with a 
valve for releasing fuel. The lighter further includes a valve actuator 
depressible by a user to actuate said valve and release said fuel, and a 
spark producing element rotatable by a user to produce sparks directed 
towards the released fuel. In addition, the lighter includes a flint 
contained within the lighter body and in frictional contact with the spark 
producing element wherein rotation of the spark producing element against 
the flint creates sparks directed towards released fuel. 
In the lighter according to the present invention, uniform spark wheel 
actuation is facilitated by decreasing the peak force required for 
rotation of the spark wheel. In an exemplary embodiment of the invention, 
a spark wheel coil having one or more loops and formed from wire having an 
outer flat face is utilized to prevent the formation of deep grooves (and 
concomitant high ridges) in the flint striking surface which increase the 
peak force required to rotate the spark wheel for generation of sparks. 
The spark wheel coil includes pitting in a transversal direction made on 
the outer surface of said one or more loops. The pitting forms projections 
which protrude from the core of the coil and which, when contacting a 
pyrophoric flint while said coil spring is rotated about its axis, produce 
a tangential dragging or cutting across the pyrophoric flint to emit an 
ignition spark. Use of wire with at least a substantially flat outer face 
ensures that during actuation, deep grooves and high ridges are not formed 
in the flint striking surface.

DETAILED DESCRIPTION OF THE INVENTION 
The following embodiments of the present invention will be described in the 
context of a lighter including a spark producing means, although those 
skilled in the art will recognize that the disclosed methods and 
structures are readily adaptable for broader application. Note that 
whenever the same reference numeral is repeated with respect to different 
figures, it refers to the corresponding structure in each such figure. 
As previously mentioned, when a flint is utilized in conjunction with a 
spark wheel cutting member fashioned from wire with a circular cross 
section or a similarly formed cylindrical cutting member, the surface of 
the flint contacting the cutting member becomes deeply grooved over time 
so as to match the cutting member surface as illustrated in FIG. 7A. 
Moreover, the rotation of the spirally formed cutting member contacting 
the flint during use acts like a screw thread on the deep angled grooves, 
urging the flint to rotate about its central axis. Eventually, the spiral 
cutting surface results in particular spots in the rotation of the spark 
wheel having increased resistance to rotation. This localized increase in 
resistance is irregular and creates a peak force for rotation that is 
difficult or impossible for some intended users to overcome. 
Thus, in accordance with the invention, uniform spark wheel actuation is 
facilitated by reducing the peak force necessary for rotation of the spark 
wheel assembly. In an exemplary embodiment of the invention, a spark wheel 
coil having one or more loops and formed from wire having a substantially 
flat outer surface is utilized. Use of wire with a substantially flat 
outer surface reduces or eliminates the deep grooves and high ridges 
formed in the flint, as illustrated in FIG. 7B. Thus, during actuation, 
such high ridges are not engaged by and do not need to be broken through 
by the spark wheel cutting member and the peak force necessary for 
rotation is thereby reduced. 
In accordance with the foregoing, FIG. 1 discloses a helical spark wheel 
coil 10 for contacting a pyrophoric flint so as to create sparks. In 
accordance with a preferred embodiment of the invention, spark wheel coil 
10 is comprised of a wire formed into numerous loops 14. The wire is 
substantially square when viewed cross-sectionally, and includes a 
plurality of projections 12 on the outer surface. As shown in FIG. 2, each 
projection 12 is preferably formed to include a tooth 13 for increasing 
cutting action between the coil 10 and a pyrophoric flint during use. The 
formation and hardening of projections 12 or teeth 13 is accomplished by 
standard forming and heat treating techniques as known is the art and 
described in U.S. Pat. No. 4,509,916, which is incorporated by reference 
herein. 
FIGS. 3A and 3B, illustrate, respectively, a half round or substantially 
half-round wire and a substantially square, grooved wire which also may be 
used to form a coiled cutting member according to the invention. The 
common element between the various wire shapes is the flat outer surface 
which permits the elimination or minimization of high ridges in the flint 
as previously explained. A narrow groove in the flat outer surface, as 
shown in FIG. 3B, may further enhance spark generation by reducing the 
size of the cuttings. 
FIG. 4 shows a spark wheel assembly 20 employing helical spark wheel coil 
10 in accordance with the invention. As shown in FIG. 4, coil 10 may be 
disposed between turning wheels 16. Coil 10 and turning wheels 16 are 
connected to one another and mounted coaxially on axle 18 so as to form 
the spark wheel assembly. 
In accordance with the invention, spark wheel assembly 20 may be used in 
conjunction with other mechanisms so as to form a lighter. More 
particularly, and as shown in FIGS. 5A and 5B, spark wheel assembly 20 may 
be mounted on the body 32 of a lighter 30 defining a central cavity. A 
pyrophoric flint 40 may be securely disposed in a cylindrical chamber 22 
positioned within body 32 to cooperate with the spark wheel assembly, and 
may be urged into frictional contact with coil 10 by a spring (not shown). 
Lighter 30 further comprises a valve actuator 34 which is pivotally 
mounted on body 32 through tabs 35, located below axle 18. Valve actuator 
34 controls the release of fluid from a fuel reservoir within lighter body 
32. 
Lighter 30 further includes a windshield 36, and a protective guard 38, 
which as previously discussed, is disposed above a portion of spark wheel 
assembly 20 so as to deter operation by unintended users. Such a lighter 
is described, for example, in detail in U.S. Pat. No. 5,520,197 to 
McDonough et al., which is incorporated herein by reference, and its 
construction and operation are well understood by persons of skill in the 
art. Similarly, the present invention is equally advantageous when 
utilized in conjunction with other child-resistancy means wherein the 
focus is on increased difficulty of spark creation by unintended users. 
Examples of lighters employing such means are U.S. Pat. No. 5,490,773 to 
Lloveras Capilla and U.S. Pat. No. 5,096,414 to Zellweger, both of which 
are incorporated by reference herein. By utilizing the present invention 
with these devices, the enhanced uniformity of operation will facilitate 
operation by intended users, without negatively impacting the 
child-resistancy. 
FIG. 6 illustrates an alternative cutting member according to the present 
invention. Rather than being formed from a coiled wire, the cutting member 
shown in FIG. 6 is formed from a cylindrical member, which may be solid or 
hollow depending on the particular spark wheel assembly. Teeth are cut 
into the outer surface of the cylindrical member in a helical pattern 
which substantially matches that achieved with a coiled wire having a flat 
outer surface. 
Various embodiments of the invention have been described. The descriptions 
are intended to be illustrative, not limitative. Thus, it will be apparent 
to those skilled in the art that modifications may be made to the 
invention as described without departing from the scope of the claims set 
out below.