Electric heating – Heating devices – Resistive element: igniter type
Reexamination Certificate
2000-02-04
2004-08-17
Jeffery, John A. (Department: 3742)
Electric heating
Heating devices
Resistive element: igniter type
C219S270000
Reexamination Certificate
active
06777650
ABSTRACT:
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.
REFERENCES:
patent: 2675068 (1954-04-01), Gollus et al.
patent: 2834904 (1958-05-01), Dickey
patent: 2850084 (1958-09-01), Kunzler
patent: 3301606 (1967-01-01), Bruno
patent: 3823345 (1974-07-01), Mitts et al.
patent: 3875477 (1975-04-01), Fredriksson et al.
patent: 4029936 (1977-06-01), Schweitzer
patent: 4905660 (1990-03-01), Leduc
patent: 4954743 (1990-09-01), Suzuki et al.
patent: 4972811 (1990-11-01), Baresel et al.
patent: 5892201 (1999-04-01), Croucher et al.
patent: 1188650 (1970-04-01), None
patent: 2-251012 (1990-10-01), None
patent: 3064715 (1999-09-01), None
Corless Peter F.
Crosby Mike W.
Edwards & Angell LLP
Jeffery John A.
Saint-Gobtain Industrial Ceramics, Inc.
LandOfFree
Igniter shields does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Igniter shields, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Igniter shields will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3339006