Igniter shields

Information

  • Patent Grant
  • 6777650
  • Patent Number
    6,777,650
  • Date Filed
    Friday, February 4, 2000
    24 years ago
  • Date Issued
    Tuesday, August 17, 2004
    19 years ago
Abstract
An igniter for use in industrial and domestic gas burning appliances is disclosed. One embodiment of the igniter includes an igniter element disposed on the longitudinal axis of a tubular shield. The shield includes at least one open slot formed therethrough for providing a passageway through which gas and air can flow, thereby forming one or more open spiral patterns in the tubular shield. Another embodiment of the igniter includes an igniter element disposed on the longitudinal axis of a spiral coil. Still another embodiment of the igniter includes an igniter element disposed on the longitudinal axis of a ceramic, cylindrical sleeve. The sleeve includes at least one hole formed therethrough for optimally exposing the igniter element to a gas flow. The tubular shield, the spiral coil, and the ceramic sleeve protect the igniter element from accidental damage or breakage, and allow an optimal flow of gas and air to the igniter element, thereby facilitating subsequent ignition of the gas.
Description




BACKGROUND OF THE INVENTION




1. Field of the Invention




This invention relates generally to igniters for gaseous fuel, and more particularly to igniters that include igniter elements and shields for protecting the igniter elements.




2. Background




Igniters, particularly, non-pilot light igniters, have been used in industrial and domestic gas burning appliances such as gas-fired furnaces, stoves, clothes dryers, and the like.





FIG. 1A

shows a conventional igniter


100


, which includes an igniter element


106


essentially disposed within an igniter shield


101


(see also

FIG. 1B

) for protecting the igniter element


106


. Typically, the igniter element


106


is a ceramic igniter element, such as that disclosed in U.S. Pat. No. 5,892,201 (“the '201 patent”) issued Apr. 6, 1999, to Croucher et al., and assigned to Saint-Gobain Industrial Ceramnics; Inc., Worcester, Mass., USA. That patent discloses inter alia a ceramic igniter element that includes a pair of conductive, end portions coupled to a highly resistive middle portion (also known as a “hot zone”). When the conductive end portions of the ceramic igniter are connected to respective leads and a voltage is applied thereto, the hot zone of the ceramic igniter rises in temperature, thereby radiating sufficient energy for producing stable, high temperatures suitable for igniting the gas.




Similarly, the igniter element


106


includes conductive end portions (not shown) coupled to a hot zone (not shown). Specifically, the conductive end portions of the igniter element


106


are connected to respective leads


110


. A portion (not numbered) of the igniter element


106


with the leads


110


connected thereto is normally cemented within a ceramic sleeve (also known as a “block”)


108


, thereby allowing the remaining portion (not numbered) of the igniter element


106


to extend from one end (not numbered) of the block


108


. Further, the leads


110


pass through the length of the block


108


and extend from the opposite end (not numbered) of the block


108


.




Accordingly, when a suitable voltage is applied across the leads


110


, a current flows from one of the leads


110


to one of the conductive end portions of the igniter element


106


; through the hot zone of the igniter element


106


, thereby causing the temperature of the hot zone to rise; to the other conductive end portion of the igniter element


106


; and, then to the other lead


110


.




Because conventional igniter elements may be subject to damage or breakage, the igniter


100


is provided with the shield


101


. For example, as shown in

FIG. 1B

, the conventional shield


101


is typically stamped out from metal sheet stock, which is usually a high temperature metal alloy. Specifically, the shield


101


includes a first portion


102




a


and a second portion


102




b


, with a pair of slots


105


formed between the first and second portions


102




a


and


102




b.






After the shield


101


is stamped out from the metal sheet stock, the first and second portions


102




a


and


102




b


of the shield


101


are typically formed into substantially tubular sections, as shown in FIG.


1


A. The insulative block


108


is then press-fit into the second tubular portion


102




b


of the shield


101


, thereby causing the igniter element


106


to be disposed within the first tubular portion


102




a


of the shield


101


.




As shown in

FIG. 1B

, a plurality of randomly spaced holes


104


is typically formed through the first portion


102




a


of the conventional shield


101


. Accordingly, when the igniter element


106


is disposed within the first tubular portion


102




a


of the shield, as shown in

FIG. 1A

, gas and air (not shown) surrounding the igniter


100


can flow through the plurality of holes


104


to the igniter element


106


, thereby facilitating subsequent ignition of the gas.




However, it has now been recognized that the conventional igniter


100


, as shown in

FIG. 1A

, can have certain drawbacks. For example, because the process for manufacturing the shield


101


, including the steps of setting-up the tooling required for making the shield


101


, stamping out the shield


101


from the metal sheet stock, and forming the first and second tubular portions


102




a


and


102




b


of the shield


101


, is relatively expensive to implement, the shield


101


substantially increases the cost of the igniter


100


.




In addition, in some applications, insufficient amounts of gaseous fuel and air surrounding the igniter


100


flow through the plurality of holes


104


formed in the shield


101


to the igniter element


106


, thereby causing the igniter element


106


to fail in successive attempts to ignite the gas. The lack of cooling airflow to the igniter element


106


also frequently causes the igniter


100


to overheat and subsequently burnout prematurely, thereby increasing the cost of using the igniter


100


.




It would therefore be desirable to have an igniter including an igniter element and a shield for protecting the igniter element from accidental damage or breakage. Such an igniter would be relatively inexpensive to manufacture and use. It would also be desirable to have an igniter including an igniter element and a shield for protecting an igniter element that has improved ignition characteristics.




SUMMARY OF THE INVENTION




The present invention provides an igniter, including an igniter shield with at least one opening formed therethrough marked by a spiral pattern, for improving ignition characteristics of a shielded igniter element and increasing the lifetime of the igniter. The present invention also provides a simplified process for manufacturing the igniter that is relatively inexpensive to implement.




According to a first embodiment of the present invention, an igniter includes an igniter element adapted for igniting gaseous fuel; and, a tubular shield for protecting the igniter element, the igniter element being disposed along the longitudinal axis of the shield, wherein the shield includes at least one opening therethrough forming an oriented spiral passageway.




According to a second embodiment of the present invention, an igniter includes an igniter element for igniting gas; and, a coil or spring-type element for protecting the igniter element, the igniter element being disposed on the longitudinal axis of the spiral coil.




According to a third embodiment of the present invention, an igniter includes an igniter element for igniting the gas; and a cylindrical, insulative sleeve for protecting the igniter element, the igniter element being axially disposed in the sleeve, wherein the sleeve includes as least one hole formed therethrough for exposing a portion of the igniter element to the gas.




The shields of the present invention protect the igniter element from undesired damage and breakage, and allow an optimal flow of gas and air to the igniter element, thereby facilitating subsequent ignition of the gas. The optimal cooling airflow toward the igniter element also prevents overheating of the igniter element, thereby increasing the useful lifetime of the igniter.




According to a fourth embodiment of the present invention, a method of manufacturing an igniter includes stamping out a shield from metal sheet stock; forming the shield into a substantially tubular section; and, disposing an igniter element on the longitudinal axis of the tubular shield.




Other aspects of the invention are disclosed infra.











BRIEF DESCRIPTION OF THE DRAWINGS





FIG. 1A

is a side view of a conventional igniter including a conventional igniter shield;





FIG. 1B

is a plan view of the conventional igniter shield shown in

FIG. 1A

, stamped out from metal sheet stock;





FIG. 2

is a side view of an igniter including a first embodiment of an igniter shield, in accordance with the present invention;





FIG. 3A

is a plan view of the igniter shield shown in

FIG. 2

, stamped out from metal sheet stock;





FIG. 3B

is a side view of the igniter shield of

FIG. 3A

, formed into a pair of tubular portions;





FIG. 3C

is a simplified top plan view of the igniter shield of

FIG. 3B

;





FIG. 4

is a side view of an igniter including a second embodiment of the igniter shield, in accordance with the present invention;





FIG. 5A

is a side view of an igniter including a third embodiment of the igniter shield, in accordance with the present invention;





FIG. 5B

is a top plan view of the igniter of

FIG. 5A

;





FIG. 6

is a plan view of an alternative embodiment of the igniter shield shown in

FIG. 3A

; and





FIG. 7

is a plan view of an alternative embodiment of the igniter shield shown in FIG.


6


.











DETAILED DESCRIPTION OF THE INVENTION




As indicated above, the invention provides new shield elements for sintered ceramic igniters. The igniter shields of the invention are characterized in several distinct aspects. In a first aspect, igniter shields are provided that have one or more spirally shaped openings along a substantial length of the shield. In a further aspect, spiral shields are provided that are of a coil or spring-like design. In a still further aspect of the invention, igniter shields are monolithically formed within a ceramic block element, with at least one opening therethrough.




Referring now in detail to the drawings,

FIG. 2

shows a side view of an igniter


200


, including a first embodiment of an igniter shield


201


, in accordance with the present invention. In an illustrative embodiment, the igniter


200


includes an igniter element


206


, such as the ceramic igniter element disclosed in U.S. Pat. No. 5,892,201 (“the '201 patent”) issued Apr. 6, 1999, to Croucher et al., the specification of which is incorporated herein by reference.




Accordingly, the igniter element


206


typically includes conductive end portions (not shown) coupled to a highly resistive middle portion (not shown), which is also known as a “hot zone.” Specifically, the conductive end portions of the igniter element


206


are connected to respective leads


210


. A portion (not numbered) of the igniter element


206


with the leads


210


connected thereto is then mounted, e.g., cemented using a suitable adhesive, within a ceramic sleeve (also known as a “block”)


208


, thereby allowing the remaining portion (not numbered) of the igniter element


206


to extend from one end (not numbered) of the block


208


. Further, the leads


210


pass through the length of the block


208


and extend from the opposite end (not numbered) of the block


208


.




It should be understood that the igniter element


206


is conventional; and, specific structures used for implementing the igniter element


206


are therefore not critical to the preferred embodiment of the present invention, and may take different forms.




Because the conventional igniter element


206


is frequently subject to accidental damage or breakage, the igniter


200


is provided with the shield


201


, which may be made of any suitable material. In this first embodiment of the shield


201


as shown in

FIG. 2

, the shield


201


is preferably made of a material that not only has sufficient hardness for protecting the igniter element


206


from inadvertent damage or breakage, but is also malleable for easily forming the shield


201


and subsequently incorporating the shield


201


into the igniter


200


. For example, the first embodiment of the shield


201


is preferably made of a high temperature metal alloy, e.g., INCONEL™ or KANTHAL™ metal alloy.




Specifically, the shield


201


includes a first tubular portion


202




a


, a second tubular portion


202




b


, and an optional connecting portion


216


for connecting the first and second portions


202




a


and


202




b


. Both the first and second portions


202




a


and


202




b


of the shield


201


have substantially circular cross-sections (see, e.g., corresponding elements


302




a


and


302




b


of FIG.


3


C), thereby defining respective diameters.




More specifically, the diameter defined by the substantially circular cross-section of the second tubular portion


202




b


is preferably slightly smaller than the diameter of the insulative block


208


. This allows the block


208


to be press-fit into the second tubular portion


202




b


, thereby causing the igniter element


206


to be disposed within the first tubular portion


202




a


of the shield


201


, as shown in FIG.


2


. Further, the second tubular portion


202




b


preferably includes a relatively narrow, elongated gap


214


for allowing flexion of the second portion


202




b


, as the block


208


is press-fit therein.




Not only does the shield


201


protect the igniter element


206


from accidental damage or breakage, but it also facilitates mounting of the igniter


200


in a target industrial or domestic gas burning appliance (not shown). For example, the second tubular portion


202




b


of the igniter shield.


201


, with the block


208


press-fit therein, provides a rigid handle that might be suitably coupled to a mounting structure (not shown) in the gas burning appliance.




It should be noted that the diameter defined by the substantially circular cross-section of the first tubular portion


202




a


is preferably larger than the diameter defined by the cross-section of the second tubular portion


202




b


. This is for providing sufficient clearance between the metallic first portion


202




a


and the igniter element


206


, thereby decreasing capacitive coupling therebetween and reducing occurrences of electric arcing. Generally, higher voltage igniter elements


206


require greater clearances between the igniter elements


206


and respective first tubular portions


202




a


. Further, the shield


201


is preferably suitably grounded for providing a degree of electrostatic shielding. The larger diameter of the first tubular portion


202




a


also facilitates the flow of gas and air to the igniter element


206


.




Further, like the second tubular portion


202




b


, the first tubular portion preferably includes a relatively narrow, elongated gap


212


for allowing flexion of the first portion


202




a


, thereby enabling the diameter of the first portion


202




a


, and therefore the clearance between the first portion


202




a


and the igniter element


206


disposed therein, to be suitably adjusted in accordance with the voltage characteristics of the igniter element


206


.




In the first embodiment of the shield


201


, a plurality of slots


204


is formed through the first tubular portion


202




a


, thereby forming open spiral patterns in the first portion


202




a


of the shield


201


. Specifically, each slot


204


is a relatively narrow opening or passage diagonally formed through the first tubular portion


202




a


. Further, the diagonal slots


204


are preferably parallel along a substantial width, W (see FIG.


3


A), of the first tubular portion


202




a


. As a result, the plurality of slots


204


winds at least a portion of the way around the longitudinal axis (not shown) of the first tubular portion


202




a


, thereby forming the above-mentioned open spiral patterns along a substantial length, L (see FIG.


3


A), of the first tubular portion


202




a.






Accordingly, when the igniter element


206


is disposed within the first tubular portion


202




a


, as shown in

FIG. 2

, gas and air (not shown) surrounding the igniter


200


flow through the gap


212


and the plurality of slots


204


to the igniter element


206


, thereby facilitating subsequent ignition of the gas.




It has been discovered that by providing the igniter shield


201


with the first tubular portion


202




a


having the plurality of slots


204


that at least partially encompasses the igniter element


206


in the open spiral patterns significantly improves the ignition characteristics of the igniter


200


.




Further, it is believed that this unexpected result arises, at least in part, as a consequence of the increased diameter of the first tubular portion


202




a


relative to that of the second tubular portion


202




b


; the dimensions of the elongated gap


212


formed by the first tubular portion


202




a


; and, the open spiral patterns formed by the plurality of slots


204


, which it is believed causes a vortex of gas and air to form within the shield


201


and around the igniter element


206


that, similar to a venturi tube, increases the flow velocity and decreases the pressure of the gas and air within the shield


201


, thereby creating a suction that draws the gas and air surrounding the igniter


200


through the gap


212


and the plurality of slots


204


toward the igniter element


206


.




Because the open spiral patterns formed by the plurality of slots


204


cause the gas and air surrounding the igniter


200


to be drawn toward the igniter element


206


, it is expected that the igniter


200


would successfully ignite the gas in many applications in which conventional systems fail. It is also expected that the increased airflow toward the igniter element


206


would reduce the occurrence of overheating of the igniter element


206


, thereby preventing premature burnout of the igniter


200


.




A preferred method of manufacturing the shielded igniter


200


of the present invention will now be described with reference to

FIGS. 3A through 3C

. As mentioned above, the igniter element


206


of the shielded igniter


200


is conventional. Accordingly, the first step of the preferred method of manufacturing the shielded igniter


200


includes providing the conventional igniter element


206


.




Next, the shield


201


is stamped out from the metal sheet stock, which may be the above-mentioned high temperature metal alloy. Specifically,

FIG. 3A

shows a shield


301


, which corresponds with the stamped out shield


201


. The shield


301


includes a first portion


302




a


, a second portion


302




b


, and a pair of slots


305


formed between the first and second portions


302




a


and


302




b


, thereby forming a connecting portion


316


.




Further, a plurality of diagonal slots


304


is preferably formed in the first portion


302




a


of the shield


301


when the shield


301


is stamped out from the metal sheet stock. Specifically, the diagonal slots


304


are formed through the first portion


302




a


of the shield


301


, each at an angle of about 45° from edges (not numbered) of the stamped out first portion


302




a


, thereby forming the plurality of slots


304


obliquely inclined along the width, W, of the first portion


302




a


. It should be noted that the total number of diagonal slots


304


formed in the first portion


302




a


of the shield


301


is generally dependent upon the actual dimensions of the first portion


302




a


, which in turn is generally dependent upon the length of the igniter element


206


(see FIG.


2


). In the preferred embodiment, as many diagonal slots


304


as possible are formed in the first portion


302




a


, while still maintaining the structural integrity of the shield


301


.




Specifically, for an igniter element


206


(see

FIG. 2

) having a typical length of from about 25 mm to about 30 mm, useful actual dimensions of the first portion


302




a


are about 30 mm by about 60 mm. Accordingly, the pitch of the plurality of diagonal slots


304


preferably ranges from about 30° to about 50°, and more preferably from about 40° to about 45°. Further, the width of each diagonal slot


304


preferably ranges from about 1 mm to about 5 mm, and more preferably from about 2 mm to about 4 mm




After the shield


301


is stamped out from the metal sheet stock, the first and second portions


302




a


and


302




b


of the shield


301


are then formed into the substantially tubular portions


302




a


and


302




b


, as shown in FIG.


3


B. Specifically, the first tubular portion


302




a


is formed for including a gap


312


, which allows flexion for subsequently adjusting the diameter of the first tubular portion


302




a


. Similarly, the second tubular portion


302




b


is formed for including a gap


314


, which allows flexion for subsequently press-fitting the block


208


(see

FIG. 2

) into the second tubular portion


302




b.






More specifically, as the first and second portions


302




a


and


302




b


of the shield


301


are formed into the tubular portions


302




a


and


302




b


, the connecting portion


316


is preferably angled for making the first and second portions


302




a


and


302




b


concentric. For example,

FIG. 3C

shows a simplified top plan view of the igniter shield


301


, including the concentric first and second tubular portions


302




a


and


302




b


. The concentricity of the first and second tubular portions


302




a


and


302




b


facilitates subsequent incorporation of the igniter element


206


(see.

FIG. 2

) into the shield


301


.




Next, the insulative block


208


(see

FIG. 2

) is press-fit into the second tubular portion


302




b


of the shield


301


, thereby causing the igniter element


206


(see

FIG. 2

) to be axially disposed within the first tubular portion


302




a


of the shield


301


and the leads


210


(see

FIG. 2

) to extend from a free end (not numbered) of the second tubular portion


302




b


. The manufactured shielded igniter


200


(see

FIG. 2

) is now ready for mounting in the target industrial or domestic gas burning appliance.




It follows from the foregoing detailed description that the igniter including the igniter element and the first embodiment of the igniter shield of the present invention yields important advantages over conventional igniters. For example, in addition to protecting the igniter element from inadvertent damage or breakage and facilitating the mounting of the igniter in the target gas burning appliance, the igniter of the present invention decreases capacitive coupling between the igniter element and the first embodiment of the igniter shield, thereby reducing occurrences of electric arcing. This is, at least in part, because of the increased diameter of the first tubular portion relative to that of the second tubular portion of the shield.




In addition, the igniter of the present invention significantly enhances the flow of gas and air to the igniter element, thereby facilitating subsequent ignition of the gas, even in many applications in which conventional systems fail. This is, at least in part, because of the increased diameter of the first tubular portion and the dimensions of the elongated gap in the first tubular portion; and, in larger part, because of the open spiral patterns formed by the plurality of slots in the first tubular portion of the first embodiment of the shield. These features also prevent the igniter from overheating and subsequently burning-out prematurely, thereby increasing the useful lifetime of the igniter while decreasing the cost of using the igniter.




Having described one embodiment, numerous alternative embodiments or variations might be made. For example,

FIG. 4

shows a side view of an igniter


400


, including a spiral coil


401


, which is a second embodiment of the igniter shield for protecting an igniter element, e.g., an igniter element


406


, in accordance with the present invention. Specifically, the igniter element


406


, a ceramic block


408


, and leads


410


, correspond with the igniter element


206


, the block


208


, and the leads


210


, respectively, as shown in FIG.


2


. However, instead of incorporating a shield such as the shield


201


(see

FIG. 2

) into the igniter


400


, the igniter


400


includes the spiral coil


401


.




More specifically, the spiral coil


401


may be made of any suitable material. In one embodiment, the spiral coil


401


is made of a material that not only has sufficient hardness for protecting the igniter element


406


from impacts, but also has sufficient resilience and elasticity for absorbing the shocks of the impacts, thereby protecting the igniter element


406


from inadvertent damage or breakage. In another embodiment, the spiral coil


401


is made of a rigid material. In the illustrative embodiment shown in

FIG. 4

, the spiral coil


401


is a coiled wire made of a high temperature metal alloy, e.g., INCONEL™ or KANTHAL™ metal alloy.




The spiral coil


401


includes a main portion


402


, which is coiled in a helix. The main portion


402


has an inside diameter that provides sufficient clearance between the metallic coil


401


and the igniter element


406


, thereby decreasing capacitive coupling therebetween and reducing occurrences of electric arcing. The spiral coil


401


is also preferably grounded for providing a degree of electrostatic shielding. For example, the spiral coil


401


may be suitably grounded using a mounting loop


418


formed thereon.




For example, the coiled wire forming the helical portion


402


of the coil


401


has a diameter and a pitch, which are selected for providing a desired level of resilience and elasticity and, more significantly, for allowing optimal flow of gas and air (not shown) surrounding the igniter


400


to the igniter element


406


. In the preferred embodiment, the coiled wire forming the main portion


402


of the coil


401


has a diameter that preferably ranges from about 5 mm to about 15 mm, and more preferably from about 7 mm to about 9 mm; and, a pitch that preferably ranges from 5° to about 50°, and more preferably from about 10° to about 30°.




The spiral coil


401


also includes a base portion


402




b


, which is tightly coiled in a helix with a substantially circular cross-section (not shown), thereby defining a diameter. Specifically, the diameter defined by the substantially circular cross-section of the base portion


402




b


is preferably slightly smaller than the diameter of the insulative block


408


. This allows the block


408


to be, e.g., securely threaded into the base portion


402




b


, thereby causing the igniter element


406


to be axially disposed within the main portion


402


of the coil


401


.




Because the above-described method of manufacturing the shielded igniter


200


(see

FIG. 2

) generally includes the additional step of setting-up the tooling required for making the shield


201


, that manufacturing method can sometimes be relatively expensive. Because no tooling is required for making the spiral coil


401


, the cost of manufacturing the igniter


400


is significantly less than that of manufacturing the igniter


200


. Advantageously, this reduces the overall cost of the igniter


400


.




In addition,

FIG. 5A

shows a side view of an igniter


500


, including a modified ceramic block


508


, which is a third embodiment of the igniter shield for protecting an igniter element, e.g., an igniter element


506


, in accordance with the present invention. Specifically, the igniter element


506


and leads


510


correspond with the igniter element


206


and the leads


210


, respectively, as shown in FIG.


2


. However, instead of incorporating a shield such as the shield


201


(see

FIG. 2

) into the igniter


500


, the igniter


500


includes the modified monolithic block


508


.




More specifically, the block


508


may be made of any suitable insulative material. Like the blocks


208


(see

FIG. 2

) and


408


(see FIG.


4


), the block


508


is preferably made of a ceramic material. Further, the block


508


includes a first cylindrical portion


502




a


, a second cylindrical portion


502




b


, and a shoulder portion


516


between the first and second cylindrical portions


502




a


and


502




b


, which have substantially circular cross-sections (not shown) that define respective diameters. As suggested in

FIGS. 5A and 5B

, the diameter of the first cylindrical portion


502




a


is preferably smaller than the diameter of the second cylindrical portion


502




b.






Further,

FIG. 5A

shows a substantially circular hole


520


formed through the first cylindrical portion


502




a


, thereby exposing portions (not numbered) of the hot zone on opposing sides (not shown) of the igniter element


506


, a portion of which is disposed in at least one slot, e.g., a slot


522


formed through a closed end (not numbered) of the first portion


502




a


(see FIG.


5


B), thereby fixedly disposing the igniter element


506


along the longitudinal axis (not shown) of the block


508


.




It should be noted that dimensions of the block


508


are generally dependent upon the length of the igniter element


506


. In an illustrative embodiment, the first portion


502




a


has a length of about 13 mm and a diameter of about 8 mm; and, the second portion


502




b


has a length of about 23 mm and a diameter of about 9 mm. Further, the hole


520


has a diameter that preferably ranges from about 3 mm to about 6 mm.




A method of manufacturing the igniter


500


includes the step of mounting the igniter element


506


with the leads


510


operatively connected thereto within the ceramic block


508


. For example, the igniter element


506


may be cemented using a suitable adhesive within the block


508


. Because the modified block


508


includes the first cylindrical portion


502




a


that encompasses and protects the igniter element


506


, the block


508


itself may be used as a fixture for the mounting step. Advantageously, the block


508


protects the igniter element


506


from accidental damage or breakage not only during operation in a target gas burning appliance (not shown), but also during manufacture of the igniter


500


.




Further, the igniter


500


is particularly useful when the target gas burning appliance is a stove top appliance (not shown). This is because the ceramic block


508


is inherently moisture-proof, which is an important feature of igniters used in cooking appliances. For example, the first cylindrical portion


502




a


with the smaller diameter may be operatively inserted into a gas burner (not shown) of the stove top appliance up to the shoulder portion


516


, thereby exposing the igniter element


506


to a flow of gas (not shown) via the opposing holes


520


for subsequent ignition of the gas. It should be noted that the block


508


not only protects the igniter element


506


from inadvertent damage or breakage, but also allows optimal exposure of the igniter element


506


to the gas flow via the holes


520


.




In addition, as to the embodiment of the shielded igniter shown in

FIG. 2

, it was described that each slot formed in the first tubular portion of the shield is at an angle of about 45°. However, this was merely an illustrative example. The slots might alternatively be formed at any angle between 0° and 90° from an edge of the stamped out first tubular portion. Further, the slots alternatively can be formed in parallel with the igniter element disposed in the first tubular portion of the shield or orthogonal thereto. Still further, neighboring slots might be formed at the same angle or alternatively at different angles, thereby forming different spiral passageway orientations through the first tubular portion of the shield.




In addition, it was described that the first embodiment of the shield includes the plurality of slots formed through the first tubular portion, thereby forming oriented spiral passageways through the first portion of the shield. It was also described that each slot formed through the first tubular portion is a diagonal, relatively narrow opening or passage. However, this was also merely an illustrative example. Each oriented spiral passageway through the shield might alternatively include a single opening or a plurality of openings.




For example,

FIG. 6

shows a stamped out igniter shield


601


, which is an alternative embodiment of the igniter shield shown in FIG.


3


A. The shield


601


includes a first portion


602




a


, a second portion


602




b


, and a pair of slots


605


formed between the first and second portions


602




a


and


602




b


for forming a connecting portion


616


. However, instead of including a plurality of diagonal slots formed in the first portion of the shield as shown in

FIG. 3A

, the shield


601


includes a plurality of oriented spiral passageways, e.g., passageways


603




a


,


603




b


, and


603




c


, formed in the first portion


602




a


of the shield


601


.




Specifically, each of the plurality of oriented spiral passageways formed in the first portion


602




a


of the shield


601


may include a single opening, e.g., a slot


604




d


included in the passageway


603




a


; or, a plurality of openings, e.g., a slot


604




a


and holes


604




b


and


604




c


included in the passageway


603




c


. Further, the opening or openings included in respective oriented spiral passageways formed in the first portion


602




a


of the shield


601


may be slots, holes, or any other geometrical shape so long as the openings and their nearest neighbor openings, if any, are arranged in the aforesaid spiral passageway orientations.




More specifically, the passageway


603




c


includes the hole


604




b


, which has two nearest neighbor openings, i.e., the slot


604




a


and the hole


604




c


. Further, the slot


604




a


and the holes


604




b


and


604




c


are arranged in the first portion


602




a


of the shield


601


so as to form a portion of the oriented spiral passageway


603




c


. As a result, when the first and second portions


602




a


and


602




b


are subsequently formed into corresponding substantially tubular portions (not shown) of the shield


601


, the passageways


603




a


,


603




b


, and


603




c


can at least partially encompass an igniter element (not shown) axially disposed within the first tubular portion. By specifying that shield opening has a nearest neighbor opening, it is meant the opening has an adjacent opening as exemplified in

FIG. 6

, such as by openings


604




a


,


604




b


and


604




c


, as well as in

FIG. 7

, such as by openings


704




a


,


704




b


and


704




c.






Further,

FIG. 7

shows a stamped out igniter shield


701


, which is an alternative embodiment of the stamped out igniter shield shown in FIG.


6


. The shield


701


also includes a first portion


702




a


, a second portion


702




b


, and a pair of slots


705


formed between the first and second portions


702




a


and


702




b


for forming a connecting portion


716


. However, instead of including the plurality of passageways formed in the first portion of the shield as shown in

FIG. 6

, the shield


701


includes a plurality of oriented spiral passageways, e.g., passageways


703




a


,


703




b


, and


703




c


, formed in the first portion


702




a


of the shield


701


.




Specifically, each of the plurality of oriented spiral passageways formed in the first portion


702




a


of the shield


701


includes at least one opening, e.g., holes


704




a


,


704




b


, and


704




c


, included in the passageway


703




a


. Further, the opening or openings included in respective oriented spiral passageways formed in the first portion


702




a


of the shield


701


have the same geometrical shape, which may be a slot, a hole, or any other geometrical shape so long as the openings and their nearest neighbor openings, if any, are arranged in the aforesaid spiral passageway orientations.




More specifically, the passageway


703




a


includes the hole


704




b


, which has two nearest neighbor openings, i.e., the hole


704




a


and the hole


704




c


. Further, the holes


704




a


,


704




b


, and


704




c


are arranged in the first portion


702




a


of the shield


701


so as to form the oriented spiral passageway


703




a


. As a result, when the first and second portions


702




a


and


702




b


are subsequently formed into corresponding substantially tubular portions (not shown) of the shield


701


, the passageways


703




a


,


703




b


, and


703




c


can at least partially encompass an igniter element (not shown) axially disposed within the first tubular portion.




The following non-limiting example is illustrative of the invention. All documents mentioned herein are incorporated herein by reference.




EXAMPLE 1




A commercially available ceramic igniter housed in a shield corresponding to the shield depicted in

FIG. 1A

of the drawings failed to ignite a high velocity gas/air mixture in a large, non-residential hot water system.




In that same hot water heater system, the same ceramic igniter housed in a shield having spiral openings and corresponding to

FIG. 3B

readily ignited the high velocity gas/air fuel mixture.




The present invention has been described in detail including the preferred embodiments thereof. However, it should be appreciated that those skilled in the art, upon consideration of the present disclosure, may make modifications and/or improvements on this invention and still be within the scope and spirit of this invention as set forth in the following claims.



Claims
  • 1. An igniter comprising:a ceramic igniter having a conductive portion and adapted for igniting gaseous fuel, the conductive portion i) coupled to a resistive hot zone of the igniter, and ii) connected to an electrical lead; and a tubular shield for protecting the igniter element, the igniter element being disposed along the longitudinal axis of the shield, wherein the shield includes a plurality of openings therethrough, each opening forming an oriented spiral passageway.
  • 2. The igniter of claim 1 wherein the plurality of openings are each a spiral slot.
  • 3. The igniter of claim 1 wherein each of the openings has a nearest neighbor opening, and the nearest neighbor of at least one of the openings is another of the openings in the same spiral passageway orientation.
  • 4. The igniter of claim 3 wherein the nearest neighbor of each of the openings is another of the openings in the same spiral passageway orientation.
  • 5. The igniter of claim 1 wherein the plurality of openings are disposed along a substantial length of the shield.
  • 6. The igniter of claim 1, wherein the tubular shield includes a first tubular portion and a second tubular portion coaxially connected at respective ends, the openings being formed through the first tubular portion, the igniter element being axially disposed in the first tubular portion.
  • 7. The igniter of claim 6 wherein the first and second tubular portions have respective substantially circular cross-sections, each cross-section defining a respective diameter, the diameter of the first tubular portion being larger than the diameter of the second tubular portion.
  • 8. The igniter of claim 6 wherein an end of the igniter element is mounted in an insulative sleeve, thereby coaxially mounting the igniter element to the insulative sleeve, and wherein the insulative sleeve is fixedly disposed in the second tubular portion of the shield.
  • 9. The igniter of claim 6 wherein the first tubular portion includes a gap formed therethrough, the gap extending along the length of the first tubular portion.
  • 10. An igniter comprising:a sintered ceramic igniter element having a conductive portion i) coupled to a resistive hot zone of the igniter, and ii) connected to an electrical lead; and a tubular shield for protecting the igniter element, the igniter element being disposed along the longitudinal axis of the shield, wherein the shield includes a plurality of openings therethrough, each opening forming an oriented spiral passageway.
US Referenced Citations (11)
Number Name Date Kind
2675068 Gollus et al. Apr 1954 A
2834904 Dickey May 1958 A
2850084 Kunzler Sep 1958 A
3301606 Bruno Jan 1967 A
3823345 Mitts et al. Jul 1974 A
3875477 Fredriksson et al. Apr 1975 A
4029936 Schweitzer Jun 1977 A
4905660 Leduc Mar 1990 A
4954743 Suzuki et al. Sep 1990 A
4972811 Baresel et al. Nov 1990 A
5892201 Croucher et al. Apr 1999 A
Foreign Referenced Citations (3)
Number Date Country
1188650 Apr 1970 GB
2-251012 Oct 1990 JP
3064715 Sep 1999 JP