Abstract:
An oil burner control system is disclosed in which an extended time may be temporarily selected, in situations such as initial set up or periodic maintenance, for priming the pipes, filters and pumps, before a safety lockout of system operation occurs, while otherwise leaving the normal safety lockout functions intact. An igniter in the system operates in an “intermittent” mode during the temporarily selected extended time, and otherwise operates in an “interrupted” mode.

Description:
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 purge” feature. For example, the pump purge may be inhibited if the primary control has been locked out since its most recent complete heat cycle. One way of doing this is to use a counter to count the number of times that the primary control has gone into lockout and, whenever the count is not zero, it would prevent the control from going into “pump priming” mode. The counter could be zeroed by techniques known only to service technicians such as pushing and holding the reset button for an extended period (e.g., 30 seconds) or pushing the reset button a predetermined number of times. 
     Other changes include 1) connecting a valve in the oil line  18  to allow independent control of oil flow by the primary controller, 2) preventing the valve from being turned on until the igniter  14  and the motor  20  have been activated; 3) the provision of a remote alarm which allows the system to be connected to the security system to provide an alert when the system is locked out; and 4) the provision of an indicator, such as an LED light, which is programmed to provide various information at various stages of operation by, not only its on or off condition, but by flashing at various rates. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a block diagram of a burner control in the prior art; 
     FIG. 2 is a block diagram of a burner control of the present invention; 
     FIG. 3 is a state diagram showing the various states of operation of the present invention; and 
     FIG. 4 is a flow diagram representing the operation of the software of the present invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     In FIG. 2, elements of FIG. 1 having the same function are shown with the same reference numerals. FIG. 2 is quite similar to FIG. 1 but includes a valve  52  connected in the oil supply conduit  18  and operable by the primary control  30  via lines  54  which are connected to terminals  56 . This allows the oil flow to be controlled independently of the operation of motor  20 . With valve  52 , oil can be prevented from flowing into combustion chamber  24  until motor  20  and igniter  14  are activated. It should be understood that controller  30  contains, among other things, a RAM for storing variables and constants (e.g., counters, resistor values, cad cell calibrations, etc), a ROM for storing the software for the system, etc., an EEPROM for storing specific configurations for the model such as the lockout timer, the model number, etc., and DIP switches to store values such as blower-off delay times to be utilized during the operation of the system as will be described. Also shown in FIG. 2 is an indicator light  58 , which may be a LED, shown on the primary control  30 , which operates to provide a visual indication when combustion in chamber  24  has occurred and has other information providing features as will be described. Also, in FIG. 2, the terminals  47 , of FIG. 1, that were capable-of being jumpered to avoid lockout, have now been placed in the interface area between the primary control  30  and the oil burner  10  as is seen by reference numeral  47 ′. So located, these terminals cannot be jumpered without removing the entire primary control  30  from the oil burner  10 . Also shown in FIG. 2 are timers  59  which are used to provide timing signals to the primary controller  30  at various stages of operation, as will be described. Finally, a remote alarm  60  is shown connected to the primary control  30  by lines  62  for purposes of producing a signal (for example to the home security system) that can alert the user that a lockout has occurred and that service should be performed. 
     The operation of FIG. 2 can be understood by reference to FIG. 3 that shows the various states that the system may occupy during its operation. The normal operating sequence will be described first as follows: 
     Upon “Power Up”, State  1 , shown by box  70 , the primary control  30  performs checks to verify that conditions which would preclude proper system operation are not present. The system would then go to Idle, State  2 , shown by box  74 , where the controller  30  would make a check to assure that the flame was out and cause the system to wait for a call for heat from thermostat  32 . Upon receiving a call for heat, the system would move to Valve On Delay, State  3 , shown by box  78 , where the controller  30  would perform certain safety checks, would again check to assure that there was currently no flame and would enable igniter  14  and energize motor  20  and start a timer to delay the opening of valve  52  until after motor  20  and igniter  14  were on. Upon completion of the timer, the system would move to Trial For Ignition, State  4 , shown by box  82 , where the controller would open valve  52  and a stream of oil and air would pass the igniter electrodes  26  and combust. When the flame is detected by cad cell  28  and a signal would be sent to controller  30 , the system would move to Carryover, State  5 , shown by box  86 , where another short delay occurs (for example 10 seconds) to assure that the flame is self sustaining at which time the igniter  14  would be extinguished and the system would move to Run, State  6 , shown by box  90 , where the heating continues until the call for heat is lost. When this occurs, the system would either move 1) directly to Idle, State  2  where the igniter  14 , blower motor  20  and valve  52  are turned off or 2) to an optional Blower Off Delay, State  7 , as shown in FIG. 3 by box  94 , where the igniter  14  and valve  52  are turned off but a timer is activated to allow the blower motor  20  to remain on a short time while the hot air is pushed through and out of the system. In either event, the system returns to State  2  where it again waits for a call for heat. If the optional Blower Off Delay State  7 , box  94  is not used, the “Lost Call For Heat” arrow from Trial for Ignition, State  4 , box  82  would also lead directly to Idle, State  2  and the “Call For Heat And No Flame” arrow would be eliminated. 
     In the event that the burner  10  is just being installed or has undergone extensive maintenance, the oil in the lines and filter may be dry in which case, the above procedure could result in a “no flame” condition at State  4  and, after a delay, the system would go to lockout, State  9 , shown by box  98  and the reset button  50  would have to be pushed to start the procedure over again. This could occur twice, after which the system would go to restricted lockout and could not again be started by merely pushing the reset button  50  again. To avoid this, the present invention provides that the reset button  50  can be pushed during States  3 - 5  and the timing in State  4  would then be increased to a value sufficient for the oil to fill the conduits and the filter and flame can be established. After this longer delay in State  4 , a detection of flame would move the system to State  5 , as before, and operation would continue as above described. The pressing and releasing of the reset button  50  during States  3 - 5  would put the system into priming mode only when there has been no lockouts which may be determined by monitoring a “lockout counter” to be described. 
     A more detailed description of the various States and their function is as follows: 
     State  1 , box  70 , is entered when power up occurs, when hardware is reset, when there is an internal error recovery, i.e., checking system values such as lock out timing and an error is discovered, or when there is a reset from a lockout state. In State  1 , the RAM is zeroed and, a short delay (e.g., 2 seconds) is initiated for system stabilization. Various safety checks are performed such as cad cell calibration, the. EEPROM values are read to verify that various parameters are within accepted standards and delay times are checked from the DIP switches. If the previous state was either Lockout, State  9  or Recycle, State  8 , to be described, the system will go to that state. Otherwise the system goes to Idle, State  2 , box  74  where it will await a call for heat. 
     In State  2 , the burner motor  20 , the oil valve  52  and the alarm  60  are off and the system is now waiting for the next call for heat. The igniter is enabled, i.e., ready to be energized, in case the blower motor  20  is stuck in an unsafe condition. The flame is monitored and the indicator light  58  will be on if there is a flame, otherwise indicator light  58  is off. A check is made of the thermostat to see if it is calling for heat and, if so, the cad cell  28  is calibrated and another short delay (e.g., two seconds) is set. After the delay the thermostat is checked again. If the thermostat is still calling for heat, a safe check is made to verify that the flame is off, and a check sum test is performed on the ROM. When everything is satisfactory, system goes to the Valve On Delay, State  3 , box  78 . 
     In Valve On Delay, State  3 , box  78 , a check is made to see if the “valve on” delay is disabled. If not, another delay is set for pre-selected time. The blower motor  20  and igniter  14  are started at the beginning of the delay. During the delay, the thermostat  32  “on” flag is monitored. If the call for heat is lost, the system returns to Idle, State  2 . If not, at the end of the “valve on” delay, the control goes to Trial for Ignition, State  4 , box  82 . 
     In Trial For Ignition, State  4 , the oil valve  52  is energized and a lockout timer is started. The thermostat “on” flag and flame level (on or off) are monitored. If the call for heat is lost, control goes to the Blower Off Delay, State  7 , box  94  or Idle, State  2 , box  74  depending on the option. Otherwise, the system stays in State  4  until either the flame is proven (i.e., “on”) or the lockout timer expires before flame is proven. If the lockout timer expires, the system goes to Lockout, State  9 , box  98 . If the flame is proven, the system goes to Carry Over, State  5 ., box  86 . 
     In State  5 , the LED  58  is turned on and the carryover timer is started. The carryover timer provides a time interval for allowing the flame to stabilize. Both the lockout timer and the carryover timer are active in State  5 . The thermostat “on” flag and the flame level are monitored and both timers are monitored. If the call for heat is lost, control goes to Blower off Delay, State  7 , box  94  or Idle, State  2 , box  74  depending on the option. If the flame is lost, the LED  58  is turned off and the lockout timer is checked. If flame is lost and the lockout timer has not expired, the system returns to the Trial for Ignition, State  4 . If the flame is lost and the lockout timer has expired, control goes from State  5  to State  4  and to Lockout, State  9 . If the carryover timer expires, control goes to Run, State  6 , box  90 . 
     In State  6 , the oil valve  52  and blower motor  20  are on but igniter  14  is turned off and the burner continues on by itself. As mentioned, when lockout occurs, the reset button  50  may be pressed to remove the lockout, but only twice. On the third time, the system goes into a restricted lockout status where the reset button must be depressed for 30 seconds before reset can occur. In state  6 , since the flame is now self-sustaining, the lockout counter is cleared and this fact is stored in the RAM and EEPROM. The system will normally stay in State  6  until the thermostat indicates enough heat has been generated. The thermostat “on” flag, the flame level and the reset button are monitored. If flame is lost, control goes to Recycle, State  8 , shown by box  102 . If the reset button  50  is pushed, the program causes the LED  58  to flash at a repetition rate that shows the general resistance range of the cad cell  28 . If the call for heat is lost, the LED is turned off to show this condition, the error counter is cleared and the system goes to Blower Off Delay, State  7 , box  94 , or as mentioned above, depending on the option, to Idle, State  2 . 
     In State  7 , the igniter  14  and oil valve  52  are turned off. It is desired that the blower motor  20  remains on for a predetermined time to move the air out of the system so, a check is made to see if the blower off delay is disabled. If not, the delay. value is obtained and the blower off is delayed accordingly. The flame and the thermostat “on” flag are monitored. If the thermostat is on, another short (e.g., two second) delay is set and the flame off is checked after which the thermostat is checked again. If the thermostat is still on, the program returns to the Trial for Ignition, State  4 , box  82 . If the flame is on, the system will remain in the Blower Off Delay, State  7 , box  94  until delay is complete after which blower motor  20  is turned off and control goes to Idle, State  2 , box  74 . 
     In Recycle, State  8 , box  102 , the system has had a proven flame that has subsequently gone out. The fact of being in Recycle, State  8 , box  102  is recorded in the EEPROM and the blower motor  20  and oil valve  52  are turned off. While in State  8 , the igniter  14  is enabled in case the blower is stuck “on”, the recycle timer is started and the LED  58  is flashed slowly to show the user that the system is in State  8 . When the recycle timer expires, the LED is turned off, the Idle, State  2  is entered and this fact is recorded in EEPROM. The Recycle feature is more completely explained and claimed in our co-pending application entitled “Limited Recycle for Primary Controls” filed Jul. 21, 2000 with Ser. No. 09/621,259 and assigned to the assignee of the present invention. 
     In Lockout, State  9 , box  98 , the state value is written to EEPROM. A lockout counter, which keeps track of the number of lockouts, is incremented and the value written to EEPROM. The burner motor  20  and oil valve  52  are turned off and the alarm is turned on. The igniter  14  is enabled in case the blower motor is stuck “on”. The LED is fast flashed to show the system is in lockout, and the reset button  50  is monitored. If the reset button  50  is pushed and the number of lockouts since the last successful run is less than three, as determined by the lockout counter, the LED and the alarm relay are turned off. The Idle, State  2 , state variable is saved in EEPROM and the system goes to Power Up, State  1 , box  70 . If there has been three or more lockouts, and if the reset button  50  is then pushed, it must be held down for 30 seconds or more after which the LED is turned off, the alarm is turned off, the Idle state variable is saved in EEPROM and the system goes to Power Up, State  1 , box  70 . Otherwise, the system continues to be in Lockout, State  9 . 
     The Lockout, State  9 , box  98  and the Recycle, State  8 , box  102  have a precaution built in. In some computers, when the power is turned off, the state of the various conditions is lost and the system starts again from zero. In the present invention, the fact that one of the “Lockout” or “Recycle” conditions existed is stored in the non-volatile memory so that when the system is again powered, the system will return to the Lockout State  9  or Recycle State  8 , as is shown by arrows  106  and  108  respectively, and will not go to State  2 . 
     FIG. 4 shows a simplified logic flow diagram for the burner control program of the present invention. It will be assumed that primary controller  30  is energized and the system is stabilized as in State  1 , discussed above. The various safety checks have been performed, the EEPROM values are read and the delay times have been checked from the DIP switches. The previous state value is determined not to be either Lockout, State  9  or Recycle, state  8  so the system is in State  2 , awaiting a call for heat. This is shown in FIG. 4 as diamond box  118 . Arrow  120  shows the continual checking for a call for heat and recycling when it is not found. When the call for heat is “yes”, as shown by arrow  122 , then the igniter  14  and the blower motor  20  are turned on and, after a delay, the oil valve  52  is turned on as explained above in connection States  3  and  4 . This is shown in FIG. 4 as box  124 . Ignition is attempted as shown by arrow  126  and the existence of a flame is checked as shown by diamond box  128 . If a flame is not detected, as shown by arrow  130 , then a check is made to determine if the “pump purge” mode has been selected. This is shown in FIG. 4 by diamond box  132 . If “pump purge” has not been selected, as shown by arrow  134 , then a check is made to see if the lockout timer has expired as shown by diamond box  136 . If the “pump purge” has been selected, as shown by arrow  138 , then the time for lockout is extended, preferably to about four minutes, as is shown by box  140  and arrow  142 . Either the non-extended or the extended lockout timer is checked in diamond box  136  and when the lockout timer has not expired, then the system reverts back to the diamond box  128 , as shown by arrow  144  to check the combustion flame. If flame is still not detected the system will continue through the loop formed by diamond boxes  132  and  136  until the lockout timer, either under non-extended or under extended time expires, at which time the system goes into Lockout, State  9 , as shown by arrow  146 , and the igniter  14 , blower motor  20  and oil valve  52  are turned off and the alarm  60  is turned on as is shown by box  150 . 
     When the combustion flame is checked in diamond box  128  and a flame is detected, as shown by arrow  152 , then there is a delay time, preferably about 10 seconds, where the flame is established as is discussed in connection with State  5  above. This is shown in FIG. 4 by box  154 . After the delay expires, as shown by arrow  156 , the system is checked to determine if the “pump purge” mode has been selected as shown by box  158 . If pump purge has not been selected, as shown by arrow  160 , the system will continue burning without the igniter on, as explained in connection with State  6  above and the igniter will be turned off as shown by box  162 . If the pump purge has been selected, as shown by arrow  164 , then the igniter  14  is not turned off. In either case, whether the igniter is on or off, as shown by arrow  166 , the system will continue to run, as in state  6  above so long as there continues to be a call for heat as shown by diamond box  170  and arrow  172 . The flame is also monitored and, if lost, the system will revert to the Recycle State  8  as explained above. 
     As soon as the call for heat is ended, as shown by arrow  174 , the igniter  14  and the oil valve  52  will be turned off and, after a predetermined delay, the blower motor  20  will be turned off, as shown by box  176  and the system will revert to the Idle, State  2  awaiting a call for heat as shown by arrow  178 . 
     It is therefore seen that we have provided an oil burner control system with a “pump purge” mode which permits an extended start-up period before lockout occurs. Many other novel features have been included, such as control of the fuel flow with a valve independently activated by the primary control, concealing the terminals from the flame detector so as to prevent the shorting out thereof, and providing a remote alarm and an LED indicator which can impart various information by the repetition rate of flashing as well as being on and off when operating in various states. 
     It will be understood that while the present invention has been shown in a preferred embodiment to operate the oil-fired burner of a furnace, the invention may be used with boilers, water heaters and other equipment. Also, where a thermostat  32  has been shown to provide the call for heat, an Aquastat® or other heat detecting device may be employed. The light  58  need not be an LED and could be any other type of indicator either visual or auditory. Furthermore, many of the logic sequences disclosed may be considered optional and alternate sequences may be utilized. 
     It should therefore be considered that the invention is not limited to the specific apparatus and logic sequences shown in connection with the preferred embodiment and applicant does not wish to be limited to such specific apparatus or logic. The scope of the invention is set forth in the claims appended hereto.