Combustion – Timer – programmer – retarder or condition responsive control – Control of purger – of scavenger or of combustion start-up...
Reexamination Certificate
2000-07-21
2002-11-12
Price, Carl D. (Department: 3743)
Combustion
Timer, programmer, retarder or condition responsive control
Control of purger, of scavenger or of combustion start-up...
C431S018000, C431S029000, C431S062000, C431S072000, C431S073000, C431S006000
Reexamination Certificate
active
06478574
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to burner systems and more particularly to an oil burner system and control that will, when needed, provide for pumping of oil through the system in a manner to avoid going into safety lockout without overriding the safety function.
2. Description of the Prior Art
Oil burner systems for use in furnaces, boilers, water heaters etc. are well known lo in the prior art. A typical prior art system for use with an oil-fired furnace is shown in FIG.
1
. In
FIG. 1
, an oil burner
10
is shown having a blower
12
, in the lower portion thereof, and a spark igniter
14
, in the upper portion thereof. A pump
16
is shown attached to the blower
12
and a supply conduit
18
connects pump
16
to a source of oil (not shown). A motor
20
, which operates blower
12
to produce a stream of air, is also shown attached to pump
16
. Pump
16
is operable by motor
20
to pump a fine mist of oil combined with the stream of air through blower
12
and into a combustion chamber
24
of a furnace (not shown). The spark igniter
14
employs a pair of spark electrodes
26
which, when energized, produce a spark across the gap therebetween to ignite the mist of oil and swirl the burning fuel into the combustion chamber
24
where the heat generated will be circulated to the house or other area to be heated. A flame detector such as a cad cell
28
views the combustion area to determine whether or not combustion has occurred.
A primary controller
30
, which may be an R8184 manufactured by Honeywell International Inc., is shown receiving signals from a thermostat
32
over lines
34
and acts to control the operation of the oil burner
10
. More particularly, when thermostat
32
sends a signal calling for more heat, primary control
30
sends a signal from terminals
40
over lines
41
to the spark igniter
14
that then operates to produce a spark across the gap between electrodes
26
. Primary control
30
also sends a signal from terminals
44
over lines
45
to energize motor
20
, blower
12
and pump
16
to start the mist of oil and air flowing from the blower section
12
to combustion chamber
24
. If the oil and air are present and the spark ignites the oil, then the flame detector
28
provides a signal over lines
46
to terminals
47
of controller
30
to indicate that satisfactory operation has occurred. Thereafter, spark igniter
14
continues to produce a spark across the gap between electrodes
26
(referred to as “intermittent” operation) and the furnace produces heat until the call for heat is lost and the motor
20
, the pump
16
and the igniter
14
are shut off.
The R8184 system works very nicely for substantially all normal situations that are encountered. Unfortunately, on occasions such as when the furnace is initially set up or when it undergoes extensive service, the oil lines and filter may be depleted and considerable time may elapse before air can be purged from the lines, the oil filter saturated and the oil pumped to the combustion chamber
24
. Under such circumstances, when motor
20
is activated to drive blower
12
and pump
16
, the spark igniter
14
produces a spark that does not ignite the oil. When the flame detector
28
does not produce a signal within a predetermined time period, (usually about 45 seconds), a safety lockout is activated which prevents further operation until the primary controller
30
is reset. A reset button
50
is provided for this purpose and after it is pushed, another delay, (sometimes as much as an additional 20 minutes) occurs before the lockout can be removed. This can be time consuming and irritating to the service technician, so many service technicians have learned that the lockout delay can be overridden by putting a jumper or short circuit across the cad cell
28
. More particularly, a wire operable to produce a short circuit can be placed across terminals
47
. Although this is not recommended procedure, it allows the technician to avoid the lockout which would otherwise occur after 45 seconds and the additional 20 minute delay before the lockout can be removed. Obviously, this permits more rapid maintenance but the result may be that the pump keeps pumping oil to the burners without ignition and an excess of oil may flow into the oil burner. This can be dangerous and at least requires significant and costly clean up. Furthermore, the technician may forget to remove the jumper and the control
30
will continue to believe there is flame when there is not, causing additional service requirements.
BRIEF DESCRIPTION OF THE INVENTION
In the present invention, several features have been provided to improve the operation of the prior art. The primary distinguishing feature is the provision of a “pump priming” or “pump purging” mode to be described below. Also, the terminals
47
to which the cad cell
28
are connected have been moved away from the rest of the terminals and placed between the primary control
30
box and the oil burner
10
surface to which primary control
30
is mounted. In this position, a jumper cannot be placed across these terminals without removing the entire primary control unit
30
. Furthermore, a restricted lockout feature is provided that only allows a predetermined number of times that the system can go into lockout before the system is disabled. This feature is disclosed and claimed in our co-pending application of entitled “Restricted Operating Modes for Oil Primary” Ser. No. 09/734,534, filed Dec. 11, 2000 and assigned to the assignee of the present invention. This restricted lockout feature requires something other than pushing the reset button
50
to restart the system (for example, a significant waiting period). The present invention provides a secondary override for use when the system is in restricted lockout. This may take the form of a pushing and holding of the reset button
50
for a predetermined time period (for example, 30 seconds) after which normal start up operation can resume. In any event, the side effect of slowing the service technician down occurs and, as described above, is costly from a time consumed measure and irritating to some technicians. To avoid this, the present invention provides a “pump priming” or “pump purge” feature to allow fuel oil to be pumped through the system without waiting the delay period that occurs by going into safety lockout. More particularly, a service technician, when he wishes to rapidly purge the system, can place the primary control in a “pump priming” mode by using a predetermined technique. For example, the reset button
50
may be pushed and released during any one of three operation states, i.e., the Valve On Delay state, the Trial For Ignition state or the Carry Over state (all of which will be described below). The “pump priming” mode allows the safety switch timing to be extended, for example, from 30 seconds to 4 minutes and permits enough time for the oil to be pumped through the system. In the present invention, the igniter is normally turned off after a short delay subsequent to combustion having occurred (referred to as “interrupted” operation) and allows power savings, less electrode wear, less noise and longer component life. However, during “pump priming” operation, an air bubble could temporarily prevent oil flow, which could result in flame out. The present invention therefore provides for changing the ignition type from “interrupted” to “intermittent” (as explained above where ignition remains on for the entire heating cycle) during “pump priming” operation. This increases the chance that the flame will be maintained even though an air bubble or other temporary obstruction occurs in the fuel line. These changes are effective for the current combustion cycle only, i.e., until the call for heat disappears. Thereafter, the primary control reverts to the normal safety switch timing and “interrupted” ignition operation on the next call for heat. If desired, a restriction may be added to prevent an unskilled person from employing the “pump
Melcher Amy L.
Simons Richard W.
Troost, IV Henry E.
Fredrick Kris T.
Honeywell International , Inc.
Price Carl D.
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