Note: Descriptions are shown in the official language in which they were submitted.
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IGNITION INDICATOR FOR GAS GRILLS
The invention relates generally to gas grills and,
more particularly, to ignition systems for gas grills.
With the cover of a gas grill in its closed position,
and the gas supply to the burner turned on, an explosive mix-
ture of gas and air will soon build up inside of the grill if
the burner is not ignited. An attempt at igniting the burner
under these conditions can result in an explosion. If burner
ignition is not made shortly after turning the gas supply on,
or if the flame blows out, it is desirable that the grill
cover be raised for clearing the explosive mixture from inside
the grill before ignition is attempted.
It would be desirable to have an arrangement for
indicating to a user whether or not the grill burner is
ignited. This would inform a user whether or not the grill
is operating properly, and would warn the user against attempted
ignition without first exhausting the interior of the grill.
Various prior arrangements exist for indicating
ignition of gas burners in gene~al. However, none of these
` are particularly applicable for gas grills and, more particularly,
to gas grills of the type which are equipped with ignition i~
systems. Examples of gas burner flame detectors incl~de
U. S. Patent No. 2,766,440 issued October 9, 1956, to Marsden
who positions a sensing device adjacent a gas burner for
generating a voltage when the burner is ignited. The voltage
is amplified and used for operating a meter. U. S. Patent
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~o. 2,761,005 issued August 28, 1956, to Chamberlain discloses
a thermocouple positioned for impingement by a gas burner
flame and provides a readout on a mater. U. S. Patent No.
3,174,533 issued March 23, 1965, to Weber discloses a spark
ignition system for gas burners, and the system includes a
device for holding a valve open when proper ignition occurs.
Failure of burner ignition results in closing of the valve to
provide the indication that ignition has failed. U. S. Patent
No. 3,136,355 issued June 9, 1964, to Weber is of general
interest for a piezoelectric ignition system including a device
responsive to the burner 1ame for arming the piezoelectric
igniter.
Prior ignition indicators for gas burners are not
easily installed in conventional gas grills in an inexpensive
manner. This is particularly true in gas grills of the type
provided with electric igniters.
Piezoelectric igniters sometimes fail to generate
sufficient voltage to cause a spark across an~electrode gap.
It would be desirable to have an arrangement for indicating
to a user whether a spark has been generated when the igniter
is operated.
~5 It is therefore the primary object of the present
invention to provide an ignition indicator which is very
inexpensive to manufacture and simple to assemble.
It is a further object of the invention to provide
an ignition indicator which is mounted on a common bracket
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with an electric igniter.
It is an additional object of the invention to provide
an ignition indicator having an indicating device mounted in a
S common housing with a control for operating an electrical
igniter.
It is also an object of the invention to provide a
piezoelectric ignition system with an indicator for indicating
whether or not an ignition spark has been generated when the
igniter control is operated.
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An aspect of the present invention resides in pro-
viding sensing means mounted adjacent a gas grill burner for
sensing ignition of the burner. Visible indicator means
external of the grill housing is responsive to the sensing
means for indicating burner ignition.
The sensing means may be mounted on a common bracket
with burner ignition means. The control for the ignition means
may be mounted in a common housing with the visible indicator
means.
In another aspect o~ the invention, a lightbulb is
connected with a piezoelectric voltage source and a spark gap
~or indicating that a spark has jumped the gap when the ig- -
niter control is operated.
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For a better understanding of the present invention,
together with other and further ob~ects thereof, reference is
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had to the following description taken in connection with the
accompanying drawings, and its scope will be pointed out in
the appended claims.
In the drawing:
FIGURE 1 is a partial perspective illustration of
a gas grill having the improvements of the present application
incorporated therein, and with a portion of the grill housing
cut-away for clarity of illustration;
FIGURE 2 is a side elevational view of an indicator
and igniter assembly;
FIGURE 3 is a rear elevational view taken generally
on line 3-3 of FIGURE 2;
FIGURE 4 is a schematic circuit diagram showing a
visible indicator connected with a piezoelectric voltage
source;
FIGURE 5 is a front elevational view of a housing
having an igniter control and an ignition indicator mounted
therein;
FIGURE 6 is a front elevational view of the housing
of FIGURE 5, and with the cover and internal components re-
moved;
FIGURE 7 is a cross-sectional elevational view
taken generally on line 7-7 of FIGURE 5;
FIGURE 8 is a schematic diagram of another control; and -~
FIGURE 9 is a schematic diagram of still another
control arrangement.
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Referring now to the drawing, and particularly to
Figure 1, there is shown a portion of a conventional gas
grill having a dished bo~tom housing 10 to which a cover is
normally hinged in a known manner. The housing 10 is supported
S on a hollow vertical post 12 through which a suitable gas
supply line extends to a gas burner 14 mounted in the lower
portion of the housing 10. A suitable con~rol valve is
provided in a known manner on the post 12 for controlling the r
supply of gas to the burner 14.
A burner igniter and flame sensing assembly 20 is
mounted to the bottom wall of the housing 10 adjacent the
burner 14. The burner igniter and flame sensing assembly 20
includes a metal bracket 24 having a bottom horizontal leg
lS 26 with suitable holes therethrough for bolting same to the
~ottom wall of the housing 10. A vertical bracket leg 28
has a flash tube 30 suitably secured thereto as by a rivet 32.
A horizontàl bracket leg 34 has a flame sensing device 36
suitable secured thereto as by a nut 38 threaded over an
extension 40 on the sensing device 36 extending through a
suitable hole in the leg 34. ~`
A pair of electrodes 44 and 46 are secured to the
rear of the flash tube 30 and have electrode tips spaced-apart
~5 to define a spark gap generally indicated at 48 in Figure 3.
As shown in Figure 4, the electrodes 44, 46 are connected to a
suitable piezoelectric high voltage source 50 which may be
o any suitable type, including those disclosed in U. S. Patent
No. 3,449,637 issued June 10, 1969,to Su~uki or ~o. 3,469,119
issued September 23, 1969, to Parkinson. A pushbutton 52 is
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manually depressed for stressing the piezoelectric crystal
to generate a voltage across the electrodes 44, 46 and cause
a spark to Jump the spark gap 48. A small lightbulb 54 is
connected in series with the voltage source 50 and the elect-
rode 46, and the bulb 54 will light when a spark jumps the gap48 to indicate that a proper burner igniting spark has been
generated. It sometimes happens that a spark does not ~iump
the gap 48 when the pushbutton 52 is depressed and the bulb
54 will inform a user when a proper spark has been generated
for achieving burner ignition.
Figures 5-7 show a housing 60 for mounting the volt-
age source 50 an~ bulb 54 o~ Figure 4, along with mounting
visible indicating means 64 which is connected ~or responding
to the sensing means 36 to provide a visible indication o~
burner ignition. The visible indicator means is shown as
including a needle or pointer 66 which moves from a normal
position to the left o~ where it is shown in ~igure 5, to
the position shown when burner ignition has occurred. A
~0 background area at 68 may be red to indicate burner ignition,
while another area 70 may be white to indicate that the burn-
er is not ignited. Obviously other visible indicators and
meters may be used i~ so desired.
The housing 60 includes a cover 74 removable secured
to a base 76 having opposite threaded bosses or ears 78 ~or
receiving screws to secure the cover 74 to the base 76. The
bulb 54, the voltage source 50 and the visible indicator 64, ~:
may all be mounted on brackets having ~langes with suitable
holes through which screws are extended ~or securing same to
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the housing base 76. Opposite tapped bosses or ears 80 are
provided for mounting the bracket for the bulb 54. Opposite
bosses or ears 82 are provided for mounting the voltage source
50. Opposite bosses or ears 84 are provided for mounting the
Visible indicator means 64. A suitable flange 90 is provided
on the housing base 76 for mounting the housing 60 to the
upright post 12.
It will be recognized that the sensing means 36 and
the visible indicator means 64 may take many different forms.
For example, thq sensing means 36 may be a thermocouple or
other similar device which generates a small current when
heated. The thermocouple is connected by suitable wires
94, 96 of Figure 2 to the indicator 64 which may be a sensitive
lS electric meter. The sensing means 36 can also be in the form
o a gas or liquid expander connected with a bellows having
an indicating needle attached thereto or connected therewith
through a mechanical linkage. Heating of the gas or liquid
expander by burner ignition will move the indicator. The
sensing means 36 may also be in the form of a bi-metallic
twister having the needle 66 or other indicator attached
thereto or connected thereto by a mechanical linkage. Twisting
movement of the bi-metallic twister upon heating thereof by
burner ignition causes the indicator to move into the burner
ignited position. It is also possible to provide arrangements
using a small battery for operating an indicator. For example,
a simple bimetal bender may be mounted adjacent the burner 14
for closing a switch when the burner is ignited for completing
a circuit rom a battery to a meter or bulb forming the in-
dicating device 64. A similar arrangement may be provided
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with a photocell in place of the bimetal for closing a
switch or completing a circuit. It is also possible to use
a thermistor in series with a battery and a meter. It is
urther possible to provide a larger battery connected with
an audible buzzer or the like. The circuit through the
buzzer would be turned on after the burner is ignited and
the visible indicator has m~ved to the burner on position.
Movement of the indicator to the burner on position would
open a switch to maintain the buzzer off. However, failure
of the burner flame would cause closing of that switch and
energiæe the buzzer for indicating flame failure. It will
be recognized that many different sensing devices may be
used for the sensing means 36 and the specific details of
such devices form no part of the present application. The
1~ ~ensing device may be one which generates an electrical
current when heated or may be one which provides a mechanical
movement on being heated.
It will be recognized that the improved ignition
indicating means may be provided with gas grills which do
not have electric ignition, and that it may also be provided
with gas grills having ignition devices of types other than
piezoelectric. Arranging the ignition sensing means 36 and
the burner igniter defined by the flash tube 30 on a common
bracket greatly simplifies manufacture and assembly of the
device. In addition, it has been found very advantageous to
mount the igniter control or voltage source 50 in a common
housing 60 with the visible indicating means 64. The common
housing is simply attached to the upright grill post 12.
Electrical wires generally indicated at 102 and 104 in Figure 1
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extend through the hollow post 12 from the devices in the
housing 60 to the sensing and igniting assembly 20.
The pushbutton 52 provides a control means for
operating the ignition means defined b~ the electrodes 44, 46
and the spark gap 48. The bulb 54 defines spark indicator
means for indicating when a proper spark has been generated
upon operation of the control means 52. If the bulb 54 does
not light upon operation of the control means 52, a user will
immediately be aware that the control 52 should again be
operated for producing the necessary spark to effect ignition.
In addition to flame sensing and indicating arrange-
ments of the type previously discussed, it will be recognized
that it is possible to use known temperature sensing and in-
dicating devices such as those discussed on pages 16-13 through
16-17 of the Mechanical Engineers' Handbook by Lionel S. Marks,
Sixth Edition, copyright 1958 by McGraw- Hill Book Company,
Inc. The sensing device can be repositioned, if necessary, ~`
to be closer to the opening in the bottom wall of the housing
10 communicating with the interior of the post 12. The remote
indicating device can also be positioned in other locations,
as on the exterior of the housing 10. The visible indicator
can be a wheel or disc rotatable past a window opening, and
carrying the words "on" and "off" to indicate the burner
condition. The housing cover 74 has suitable window openings
for the spark indicator bulb 52, and for the flame indicator 64.
Another cover opening is provided for the pushbutton 54.
Figure 8 shows another control arrangement wherein ;;
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an electrical wiper 102 is connected with the knob 104 for
operating the gas valve for the burner 14. Rotation of the
knob 104 clockwise to any on position will cause the wiper 102
to engage arcuate contact 106 connected with audible or visual
indicator 110, bimetal 112 and battery 114. The indicator
110 may be a buzzer, light or meter and will give a warning
until the burner is ignited; whereupon the flame will cause the
bimetal 112 to move away from the contact 116 and de-energize
the indicator 110. This arrangement will give a warning
whenever the gas supply is on and the burner is not ignited.
Figure 9 shows an arrangement wherein gas valve control
knob 104 is connected with a large toothed pinion 120 engaging
a vertically slidable rack 122 having a slot 124 receiving a
pin 126 on a stem 128 attached to a piston 13~ in a dashpot
132. A spring 134 normally biases the piston 130 down in
Figure 9 to extend stem 140 into the path of a shoulder 142
on the pushbutton 52 which operates the igniter. When the
knob 104 is turned clockwise to any on position, the rack 122
will move down far enough to allow movement of the pin 126
relative to the slot 124 far enough to move the stem 140 into
the path of the shoulder 142. The dashpot can be one which
takes around five seconds for the piston 130 to move fully
down. This would allow around five seconds ater the gas
is turned on to effect ignition. Afterwards, the gas control
knob 104 must be turned off to rearm the dashpot 132 before
reignition can be attempted. This will warn the user to
open the grill cover and vent same.
The bimetal 112 defines a deactivator means for
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deactivating the indicator 110 once the burner is ignited.
The arrangement of Figure 9 provides a delay blocking
means ~or blocXing operation of the igniter control a pre-
determined time after the gas supply valve is turned on.
While there have been described what are at present
considered to be the preferred embodiments of this invention,
it will be obvious to those skilled in the art that various
changes and modifications may be made therein without departing
from the invention, and, it is aimed, therefore, in the
appended claims to cover all such changes and modifications
which all within the true spirit and scope of the invention.
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