US2175341A - Control system - Google Patents

Description

K. CLARK CONTROL SYSTEM Oct. 10, 1939.

INVENTOR.

AZWML CZARA msaw Filed Nov. 15, 1937 Patented Oct. 10, 1939 .UNITED STATES PATENT OFFICE CONTROL SYSTEM Kendall Clark, South Bend, Ind., assignor to International Engineering Corporation, a corporation of Illinois Application November 15, 1937, Serial No. 174,565

8 Claims. (Cl. 158-28) This invention relates to control systems for Figure 6 is another section through the second oil burners and the like and. particularly to a safety device, on the line 66 of Figure 5. safety means for holding the circuit open when In the arrangement of Figures 1-3 the system something goes wrong with the burner, and to a includes a burner having electrically-controlled 5 control circuit including such means. operating means such as a motor of a type An object of the invention is to provide imhaving a starting winding l2 and a running windproved automatic means for opening the main ing H. An electric igniter, shown as a resistance circuit of an oil burner or the like in the event [6 adapted to become hot enough to ignite the that the burner fails to ignite upon starting. fuel-air mixture issuing from the burner, is con- 10 Another object is to provide an eflective and nected in series with the starting winding [2 so 10 simple time delay switch for use in such means. that they are always on at the same time and Preferably this is in the form of a thermally acoff at the same time. tuated time delay switch. I prefer that the time- Such burners are usually provided with stack delay switch used in the described control cirswitches such as the one indicated diagrammaticuit should be provided with simple manuallycally at l8. This switch is arranged on the stack 5 operated resetting means. A still further object or chimney or chimney connection through which is to provide a switch such as above described with pass the hot burner gases from the furnace with such manual resetting means combined with adwhich the burner is associated. ditional switch means operable to again start the The particular stack switch illustrated has a burner-even if it has been automatically rendered bimetallic blade 20 in the path of the flue gases, 20 inoperative by a stack element such as is normally and carrying contacts either engaging (when the employed with oil burners, and which functions burner is not operating and the stack is cold) when the burner fails to operate properly. a contact 22 or (when the blade is acted on by In the arrangements herein described these obhot flue gases) a contact 24. The blade 20 is 25 jects are attained by employinga bimetal thermoarranged to move rapidly from contacts 22 and 25 static element carrying a contact normally disen- 26 to contact 24 as the hot combustion products gaged from a second contact, the two contacts actuate it, and to return w y from o ta 4 comprising a switch in one of the lines of the to contacts 22 and 26 as blade 20 cools after main burner'circuit, latch means holding the com the combustion ceases. The contact 22 is yield- 0 tacts closed and being adapted to release on the ingly d, d W en the b ade 20 is cold 30 heating and flexing of the bimet l el ment, toit forces the contact 22 against a fourth contact gether with a heater coil for heating the bimetal- 26. When the burner is operating, contacts 22 he element as long as the igniter continues to and 25 p g ap operate. Since the igniter is turned off automati- The y m in des operating circuit lin 30 cally when the burner becomes effective, the conand 32, connected 110 a SOLIICE 0f alternating C11!- 35 tacts only separate to break the circuit wh n rent electrically under the control of the usual something goes wrong and the bu f il t room-thermostat switch 33. Disregarding the i nit ro rl safety device described below, when the burner is h above and other obje ts and fe ture of not operating the circuit is from line wire 30 to the invention, including various novel combinathe contacts on blade 20 and thence, in two 4 tions and desirable particular constructions, will anel Paths (1) Contact St rting winding l2 be apparent from the following description of the m f (2) Contact 2- c0ntact 25-runillustrative embodiments shown in the accomnmg wmdmg to the other hne wlre when panying drawing in which: the burner starts and blade 20 actuated by the heat of combustion, shifts to close the contact 45 6 :15: g 3;? wmng diagram of one form of 24 and open contacts 22-26, the circuit is from wire (ill-blade 20-contact 24-running winding Figure 2 1s a section through the novel safety wire devtce mcotpomted theremf The novel safety device in one structural form Flgure 3 15 an end elevatmn of the safety is shown in Figures 2 and 3. It includes a base 40 50 Vice; on which is mounted a fixed contact 42 having a figure 41S a Wmng diagram of a Second binding post 44, a yielding contact 46 normally bodlment; sprung away from contact 42 and having a bind- Figure 5 is a section through the safety device ing post 48, and a bimetallic blade 50 secured to of said second embodiment; and the base 40 at one end and tensioned to spring 55 away from contact 46 but movable against its own yielding resistance to engage the contact 46.

The free end of the blade 5G is formed as a latch 52 extending through an opening in the base 40 and yieldingly interlocking therewith to hold the blade 5% against the contact 463. .16 base 45 also supports a heating resistance 54 having at one end a binding post 56 and having its other end secured electrically to the blade 59 by a handle 58 which serves as manually-operable means for engaging the latch 52 with the base. The handle 58 also serves as means by the manual operation of which the contact 45 can be forced against the contact 42. A cover 50, having an opening 62 for the handle 58, may also be provided.

The line wire 30 is connected through binding post 56 to the resistance 54; the contact 46 is connected through binding post 48 andawire 54 to the bimetallic blade 20 of the stack switch; and the contact 42 is connected through binding post 44 and a wire 66 direct to the starting winding it independently of the stack switch.

In operation, when the room thermostat closes the circuit to turn on the burner, the circuit is from wire 3!] through resistance 54, to blade 50, contact 46, wire 64, blade 20, and thence to line wire 32 through the parallel circuits (1) contact AZ-starting winding I2igniter l 6, and (2)' contact 22-contact ZEi-running winding [4.

The electrical resistance of the above-mentioned circuit is of a much lower value than circuit 2, and the combined parallel circuits cut down the total resistance so that a fairly heavy current flows through the resistance 54. Normally the burner starts promptly, causing the stack switch Hi to operate, and the circuit is then: line wire an resistance 54blade 50- contact 46wire fi l-blade 20-contact 24 running winding l41ine wire 32. has a fairly high overall resistance, and not enough current flows through it to heat the resistance 54 enough to afiect the bimetallic blade 50. 7

If, however, the burner for any reason fails to ignite, after a short predetermined interval the heavy current flowing through the parallel. circuits l and 2 heats resistance 54 and deforms the blade 5!! enough to release the latch 52. whereupon the circuit is automatically suddenly broken, and will remain open until closed again manually. After making any necessary repairs, the operator lifts the handle 58 to cause the latch 52 to re-engage.

The stack switch blade 20 sometimes sticks in the hot position or reaches some intermediate position after the room thermostat opens and consequently, when the space being heated has cooled off and the thermostat again closes, the

ing 12 and the igniter l6 independently of the stack switch.

The handle must be held up until ignition actually takes place, since, if it were released, the

igniter would be de-energized while.the motor it would continue to run and discharge oil into the furnace. If ignition takes place, the burner will operate all right until the room thermostat opens. If it does not take place, the oper- This circuit ator need only push down on the handle 58 to release the latch 52 to stop the motor.

I have observed that if a burner in which the stack switch has stuck is caused to operate, the reheating often releases the mechanism of the switch and it will operate thereafter for a long time without further trouble or need of repair. Consequently, my novel auxiliary circuit may result in saving of repair bills, but even if this does not occur it affords means of obtaining heat in the interval between the discovery of the trouble and the arrival of a service man. Another advantage of my novel circuit arises in placing this auxliary circuit and switch in conjunction with the lockout switch reset so that no confusion arises as to the means of restarting. the burner when it fails to operate. The control system also functions as a safety device against a failure of the source of electric power. A safety device is very essential for oil burning systems of the type described above having intermittent ignition. It is essential to insure that the ignition device be in operation when the burner starts after a short current interruption; otherwise oil and air in an explosive mixture ratio are introduced into the combustion chamber, and subsequent ignition might cause a disastrous explosion. In the event of power failure, the motor l0 stops and the oil burner no longer operates. When the power is turned on again, the motor ID has its running winding l4 connected to lines 30 and 32, but it cannot start as its starting winding [2 has been disconnected.

The arrangement of Figures 4-6 differs from that described above only in that the heating resistance I54 is connected at its ends to binding post 56 and, through a conducting bracket I55, to binding post 44. The blade 50 has its own binding post I50, to which line wire 30 is connected. tween the starting wind l2 and the contact 22, so that it is not inthe running winding circuit and no current passes through it when the burner is running.

While two illustrative embodiments have been described in detail, it is not my intention to limit the scope of the invention to those particular embodiments, or otherwise than by the terms of the appended claims.

I claim:

1. A control system for an oil burning furnace or the like comprising. in combination with a burner mechanism including a motor with a starting winding and a running winding and an igniter device, and with operating circuit lines, a stack switch normally connecting said lines through both windings and through the igniter device when the burner is not operating and the furnace is cooled and normally connecting said lines through the running winding only when the burner is operating and the furnace is hot, and a safety switch connected in one of said lines and which is not afiected by the current passing when the circuit is closed through the running winding only and which is provided with means for automatically opening the circuit and locking it open when the current passes for a pre-determined time through the igniter and through both windings without starting the burner, said safety switch having manually operable means for closing an auxiliary circuit between said lines around the stack switch and directly through the igniter device and through the starting winding, whereby the burner can be started in the event the stack switch fails to returnto the cold position.

2. A-control'system for an oil burning furnace or the like comprising, in combination with a burner mechanism including a motor and an igniter device, and with operating circuit lines,

a stack switch normally connecting said lines through said motor and through the igniter device when the burner is not operating and the furnace is cooled and normally connecting said lines through the motor only when the burner is operating and the furnace is hot, and a safety switch connected in one of said lines and which is not aiTected by the current passing when the circuit is closed through the motor only and which is provided with means for automatically opening the circuit and locking it open when the current passes for a pre-determined time through the igniter and through the motor without starting the burner, said safety switch having manually operable means for closing an auxiliary circuit between said lines around the stack switch and directly through the igniter device and through the motor, whereby the burner can be started in the event the stack switch fails to return to the cold position.

3. A control system for an oil burner or the like comprising, in combination with operating circuit lines and a burner having electricallycontrolled operating means and with an igniter, means for connecting said lines through both said first means and the igniter when the burner is first turned on and for connecting said lines through said first means only after the burner starts, and a safety device connected to open the circuit automatically after a predetermined time during which the current passes through both said first means and the igniter, if the burner does not start, said safety device including means manually operable when the circuit is open for closing the circuit from said lines around the second means directly through the igniter device and said first means,

4. A control system for an oil burner or the like comprising, in combination with operating circuit lines and a burner having electricallycontrolled operating means and with an igniter, means for connecting said lines through both said first means and the igniter when the burner is first turned on and for connecting said lines through said first means only after the burner starts, and a safety device connected to open the circuit automatically after a predetermined time during which the current passes through both said first means and the igniter, if the burner does not start, said safety device including means manually operable when the circuit is open for closing the circuit from said lines around the second means directly through the igniter device and said first means, said safety device being provided with latch means operating automatically when the circuit is opened to hold the circuit open until closed manually.

5. A control system for an oil burner or the like comprising, in combination with operating circuit lines and a burner having electricallycontrolled operating means and with an igniter, means for connecting said lines through both said first means and the igniter when the burner is first turned on and for connecting said lines through said first means only after the burner starts, a normally-stationary member having a contact and a bimetallic blade having a contact engaging the first contact and which contacts are connected in one of said lines in series with a heating resistance adjacent said blade to open the two contacts after a predetermined interval during which current passes through both the igniter device and said first means, said blade having a latch normally holding the contacts closed against the yielding resistance of said blade and which is released by the deformation of the blade caused by heating it during said predetermined interval, manually operable means for relatching said blade with the contacts closed, said stationary member being yieldable with the bimetallic blade when said contacts are engaged and the manually operable means is operated, and a third contact engaged by the first contact when said member so yields and which closes an auxiliary circuit directly through the igniter and through said operating means around said second means.

6. A control system for an oil burner or the like comprising, in combination with operating circuit lines and a burner having electricallyeontrolled operating means and with an igniter, means for connecting said lines through both said first means and the igniter when the burner is first turned on and for connecting said lines through said first means only after the burner starts, a normally-stationary member having a contact and a bimetallic blade having a contact engaging the first contact and which contacts are connected in one of said lines in series with a heating resistance adjacent said blade to open the two contacts after a predetermined interval during which current passes through both the igniter device and said first means, manually operable means for moving said blade against its own yielding resistance to re-engage said contacts, said stationary member being yieldable with the bimetallic blade when said contacts are engaged and the manually-operable means is operated and a third contact engaged by the first contact when said member so yields and which closes an auxiliary circuit directly through the igniter and through said operating means around said second means.

7. A control system for an oil burner of the like comprising, in combination with operating circuit lines and a burner having electricallycontrolled operating means and with an igniter, means for connecting said lines through both said first means and the igniter when the burner is first turned on and for connecting said lines through said first means only after the burner starts, a normally stationary member having a contact and a bimetallic blade having a contact engaging the first contact, said contacts being arranged in one of said lines, a heating resistance connected in the part of the circuit including the igniter and arranged adjacent said blade to heat the blade as long as the igniter is on to open the circuit automatically after a predetermined interval if the igniter is not turned oir, said blade having a latch normally holding the contacts closed against the yielding resistance of said blade and which is released by the deformation of said blade caused by being heated by said resistance, manually-operable means for re-latching said blade with the contacts closed, said stationary member being yieldable with the bimetallic blade when said contacts are engaged and the manually-operable means is operated, and a third contact engaged by the first contact when said member so yields and which closes an auxiliary circuit directly through 'the igniter and through said operating means around said second means.

8. A control system for an oil burner or the like comprising, in combination with operating circuit lines and a burner having electricallycontrolled operating means and with an igniter, means for connecting said lines through both said first means and the igniter when the burner is first turned on and for connecting said lines through said first means only after the burner starts, a normally stationary member having a contact and a bimetallic blade having a contact engaging the first contact, said contacts being arranged in one of said lines, a heating resistance connected in the part of the circuit including the igniter and arranged adjacent said blade to heat the blade as long as the igniter is on to open the circuit automatically after a predetermined interval if the igniter is not turned on, manually-operable means for moving said blade against its own yielding resistance to re-engage said contacts, said stationary member being yieldable with the bimetallic blade when said contacts are engaged and the manually-operable means is operated, and a third contact engaged by the first contact when said member so yields and which closes an auxiliary circuit directly through the igniter and through said operating means around said second means.

KENDALL CLARK.

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