US2237120A - Ignition control means - Google Patents

Description

April 1, 1941 v SQDERHQLM 2,237,120

IGNITION CONTROL MEANS Filed Jan. 3, 1938 loses.

0n heai'mg 54 and 55 closes before 45 and 46 opens- On coolmg 54 and 55 o ens beForG 45and 46c a. .2 :3 9 INVENTOR 3 Laurenusoderholm m a, 5! BY g #M R ATT RNEY Patented Apr. 1, 1941 rem'rron comor. mums Lauren V. Soderholm, Minneapolis, Minn, assignor to.

Minneapolis-Honeywell Regulatorv Company, Minneapolis, Minn, a corporation of Delaware Application January s, 1938, Serial No. 183,020 llfilaims. (Cl. 158- 128) This invention relates to a switching means in general and to the combination of this switching means in an oil burner control system for controlling the ignition thereof.

Ignition switches have long been provided for turning on and ed the ignition oi an oil burner apparatus, but it has been found necessary in the past to utilize two switches connected in series for this purpose, one beingoperated upon the starting of the oil burner apparatus to start the ignition and the other being operated upon the establishment of combustion to stop the ignition.

"The 'use of two switches for accomplishing this result necessarily increases the cost of an oil burner control system.. Also the switch. that is operated by the combustion responsive device carries relatively high currents and must either be of the mercury switch type or if open contact, it must be of-the snap action type. Either of these types of switches require a relatively large amount of work by the combustion responsive device for operating the same which is diflicult to obtain and still keep the cost and size of the combustion responsive device within reasonable limits.

It is therefore the prime object of this invention to eliminate the above difllculties by providing a new and novel switching mechanism for controlling the ignition oi an-oil burner apparatus.

In carrying out this invention a single switch is utilized for turnng on the ignition means when the oil burner apparatus is. placed in operation and for turning oil the ignition means when combustion is established. Also this switch is closed when the oil burner apparatus is placed in operation by means of the main operating relay which has comparatively unlimited power and the switch is opened upon the establishment of combustion by having the combustion responsive device merely release a latch which requires only a relatively small amount of work.

Accordingly, an object of this invention is to provide a single switch for controlling the operation of the ignition of an oil burner apparatus.

Another object of this invention is to operate this switch by-the main relay of the oil burner control system which has relatively unlimited power and to release the switch by the combustion responsive device with the expenditure of a minimum amount of eiTort thereby.

A further object of this invention is to provide a new and novel switching mechanism.

Other objects and advantages will become apparent to those skilled in the art upon reference to the accompanying specification, claims and drawing in which:

Figure l is a vertical sectional view of the combustion responsive device taken substantially along the line i-l-of Figure 2; v Figure 2 is an end elevational view of the combustion responsive device looking toward the left in Figure 1 and also an elevational view of the main operating relay;

Figure 3 is a sectional view of aporticn of the combustion responsive device illustrated in Figures 1 and 2 and taken substantially along the line 3-3 of Figure 2;

Figure 4 is a side elevational view ofthe main operating relay showing the relay energized and the ignition switch closed;

Figure 5 is a side elevational view of the main operating relay showing the relay energized and the ignition switch opened; and.

Figure 6 is a schematic wiring diagram of the oil burner control system of this invention.

Referring now to Figure 1, the combustion control device is generally designated at H) and is shown to comprise a mounting member ii ,to which is secured a tube l2 which is adapted to extend into the combustion chamber or into a stack through which the gases of combustion pass. One end of a bimetallic element i3 re sponsive to combustion temperatures is secured to the tube l2 and the other end is connected to:

a rod it which extends concentrically through the tube It. The rod i4 is journaled in a bearing i5 and is connected to a connecting member ii. A

spring it tends to urge the connecting member i8 and hence the rod i4 towards the right. Upon a decrease in combustion temperature afiecting the bimetallic element i3, the rod l4 and connecting member I6 are moved to the left against the action of the spring l1 and upon an increase in temperature they are moved to the right in the direction indicated by the character H.

An operating rod i8 is suitably secured to the connecting member i6 and extends through an opening N in a base 20 preferably made of insulating material and suitably connected to the mounting member II. The rod l8 isiprovided with a circumferentially grooved portion 2| which extends outwardlybetween brackets 26 and I suitably secured to the base 20. The brackets 24 and 25 are provided with pins 28 and 21, and upon these pins are mounted switch operating -members and 50, respectively.

Referring now to Figure 3, the switch operating member 30 is shown to comprise arms 28 and 29 pivotally mounted on the pin 26. Abutting the arms 28 and 29 are friction washers 3| and 32 and abutting thesefriction washers are operating members 33 and 34 formed with grooves which engage the grooves of the grooved member 2| of the rod I8. A spring 35 is interposed between the operating members 33 and 34 so that the operating members are frictionally coupled to the arms 28 and 29 of the switch operating member 30. Upon an increase in combustion temperature affecting the bimetallic element l3, the

rod I8 is moved to the right as viewed in Figure 1 and the switch operating member 38 is moved in a counter-clockwise direction as viewed in Figure 1, and upon a decrease in temperature the rod I8 is moved to the left to cause clockwise movement of the switch operating member 30. The switch operating member 30 is provided with an extension 38 which is adapted to engage spaced stops 39 to limit the amount of rotation base 20. A spring 633 maintains the follower it in engagement with the switch operating member 30. The lever ll carries an arm 46 which in turn I carries a contact 65 adapted to engage a-stationary contact 65 carried by' a bracket 4W suitably secured to the base 20. Upon a decrease in temperature which causes clockwise rotation of the switch operating member 38, the contact 65 is moved into engagement with contact 65 and upon an increasein temperature which causes counterclockwise rotation of switch operating member .30, contact 65 moves out of engagement with con- .tact 36. The contacts 435 and 46 form what are commonly termed cold contacts.

The switch operating member 55 is operated by grooved operating members 5| and 52 in exactly the same manner as the switch operating member 30 is operated, and therefore a further description of this portion of the device is not considered necessary. carries an arm f53-upon which is mounted a contact 56. The contact 541 is adapted to engage a stationary contact 55 carried by a bracket 56 suitably secured to thebase 20. A stop 57 also secured to the base limits counter-clockwise rotation of the switch operating member 50; Upon an increase in temperature affecting :the thermostatic element I3, the switch operating member 50 is'moved in a clockwise direction as viewed in Figure 1 to move the contact 56 into. engagement with contact 55, and upon a decrease in temperature the switch operating member 50 is moved in a counter-clockwise direction into engagement with stop 51 to separate the contacts 54 and 55. The contacts 54 and 55 form what are commonly termed hot contacts.

,The parts thus far described are so arranged that with the thermostatic element l3 cold, as

when .combustion is not present, the contact 45 is engaging the contact 46 and the contact operating member 50 is in an extreme counter-clockwise position against the stop 51 to maintain the contacts 54 and 55'separated, Upon the establishment'of combustion, the thermostatic element I3 heats up to move the rod l8 toward he right The switch operating member 50 which first causes engag ment of the contacts 54 and 55 and then separates the contacts and 46.

When combustion is stopped and the thermostatic element i3 cools, contacts 56 and are first separated and then contact 45 is moved into engagement with contact 46. In other words, upon an increase in temperature the switching actions of the contacts 54 and 55 and the contacts and to overlap, while upon cooling the switching actions do not overlap.

Referring now to Figures 2, 4, and 5, the main operating relay is shown to comprise a core 6| suitably secured to the base 20 and having an operating coil 62. An armature 53 pivoted at 64 to an extension 65 of the core 6| is attracted toward the core upon energization of the coil 62. The armature 63 carries an insulating member 56 to which issecured, an arm 61 carrying a contact 68 which is adapted to engage a contact 69 carried by a'stationary bracket 10 when the operating coil 82 is energized. The insulating member 63 also carries an arm II (Figure 2) to which is secured a contact 12 which is also adapted to engage a contact I3 carried bya bracket 1% when the operating coil G2 is,energized. The contacts TI and 72 form a load switch for the burner motor, while the contacts 68 and 69 form a maintaining switch for the operating coil 52 of the relay.

The insulating member 66 also carries an arm 78 upon which is mounted a bracket l9 carrying a pin 86. A contact member 8| is pivotally mounted on the pin 80 and isbiased in a counterclockwise direction, as viewed in Figures 4 and 5, by a spring 82. Counter-clockwise movement of the contact member BI is limited by an adjustable stop 83 suitably secured to a bracket 84. When the spring 32 is overcome in a manner to be pointed out immediately hereafter, the contact member 8| engages a contact 85 carried by a bracket 85 when the operating coil 62 of the relay is energized. The contact arm 8| and the contact 85 form an ignition switch for controlling an ignition means.

In order to overcome the spring 82, the contact arm 8| is provided with an extension 81 carrying a pin 88 which is engaged by an inner surface on a cam member 89 mounted on the pin 26, as shown'in Figure 4. Accordingly, when the pin 88 engages the inner surface 90 as shown in Figure 4, the pivotal connection between the contact arm BI and the arm 78 is maintained relatively rigid'so that the contact arm 8| is moved into engagement with the contact 85 when the operating coil 62' of the relay is energized. The cam means 89 is provided with an opening 9| which when moved adjacent the pin 88 allows the spring 82 to move the contact arm 8| in a counter-clockwise direction to disengage the contact arm 8| from the contact 85, even though the relay coil 62 is energized as shown in Figure-5. The position of the cam means 89 is controlled by an arm 92 carried by the switch operating member 30. When combustion is not present, the cam means 89 assumes the position shown in Figured to maintain the connection between the arm 78 and the contact arm 3| substantially rigid so that the contact arm 8| is moved into engagement with contact 85 when the operating coil 62 is energized. -When combustion is established, the cam means 89 is moved by the arm 92 in a clockwise direction, as viewed in Figures 4 and 5, to align the opening 9| of the cam" means 89 with the'pin '88 whereupon the pin 88 isreleased to allow the spring means 82 to move the contact arm 8| out of engagement with the contact 85. This operation occurs at substancontact 46.

out of engagement When the relay coil 62 is deenergized while the parts are in the position shown in Figure the armature 63 will drop out even though the contact arm 8| is engaging the stop 83 and the spring82 is tending to hold the armature 63 in. This is due to thefact that spring 82 is quite weak and although it is strong enough to break 7 contactsfll and 85 after combustion has been established, it is not strong enough to prevent armature 63 from dropping out when the coil 62 is deenergized. When the armature 63 drops out and the contact arm 8i is engaging the stop 83 .the pin 83 will move inwardly oi the cam means 89 sothat when the thermostatic element it decreases in temperature the cam means 823 may rotate in a counter-clockwise direction to cause the inner surface W to engage the pin 88. In'this manner the connection between the arm l8 and the contact arm 88 is made substantially rigid as shown in Figure 4 preparatory to the next cycle of operation.

' Referring now to the schematic wiring diagram of Figure 6, a space thermostat is generally designated at 95 and may comprise a thermostatic element 95 for operating switch arms iii and 99 with respect to stationary contacts 98 and its. The contacts are so arranged that upon a decrease in space temperature the switch arm 51 first engages the contact 93 at, S y 72, and theswitch arm as next engages the contact tilt, at, say 70". The oil burner motor is designated at Hi2 and the ignition means therefor is designated at W3. A safety switch is generally designated at it? and may comprise a thermostatic element i336 adapted to engage a contact it? and adapted to be heated by a heater element lot. When the heater element 598 is an ergized, the thermostatic element M36 is moved to the right after a predetermined length of time to disengage the contact Hill.

The relay in Figure 6 is shown to comprise the operating coil 52, the maintaining switch formed by arm ti and contacts 68 and tihand the burner switch formed by arm ii and contacts i2 and it. The combustion responsive device generally designated at ill shows the contacts 65 and 66 forming the cold contacts, the contacts 5 3 and 55 forming the hot contacts and the contact arm 8i andthe stationary contact 85 forming the ignition 'switch. Power is supplied to the control system by vmeans of a step-down transformer its having a secondary iii and a primary H2 connected across line wires lid and ti l leading from some source of power (not shown).

Assume now that the space thermostat is satisfied, accordingly the relay is dropped out, the burner motor W2 and. the ignition means its are deenergized and the cold contacts 65 and d6 are closed. When the temperature ate footing the thermostat 95 decreases to '30 so as to make contacts 99 and Hill, a starting circuit is completed from the secondary iii through contact 98, switch arms 97' and 89, contact int. operating coil 52, cold contacts 4325 and as, heater element 098, thermostatic element its, and contact ill! of the safety switch Hi5 bacls to the secondary iii. Completion of this starting circuit energizes the operating coil 62 to pull in the relays When the relay is pulled in, contact 68 engages contact 69, contact 12 "engages contact l3, and contact arm 8i engages contact arm 1!, and burner motor I02 back to the other line wire H4. In this manner the burner motor is operated. Movement of the contact arm 8! into engagement with the contact 85 completes an ignition circuit which may be traced from the line wire iii through contact arm 8i, contact 85 and ignition means its back to the line wire lid. In this manner the ignition means is energized simultaneously with the placing in operation of the burner motor W2.

Movement of the contact 88 into engagement with contact 69 completes a maintaining circuit for the operating coil 52 oi the relay which may be traced fromthe secondary iii through contact 38, switch arm ill, thermostatic element 96. contact 89, contact 68, switch arm iii, operating coil 62, cold contacts iii and to, heating element 7 Hit, thermostatic element Hi6 and contact iill back to the secondary Hi. This circuit will maintain the operating coil 62 energized and hence the relay pulled in even though the temperature should rise above 70.

If upon operation of the burner motor m2 and the ignition means 962] combustion is not established within a predetermined length of time. the heater element m8 will flex the thermostatic element tee of the safety switch to the right to disengage the contact till! thereby breaking both the starting and maintaining circuits outlined above to drop out the relay and cause shutting down oi the burner motor Hi2 and the ignition means M353. If, on the'other hand, combustion is successfully established the thermostatic element it or" the com-hustion responsive device it heats up and moves the contact 86 into engagement with contact 55 to complete a running circult for the operating coil 82 which may be traced from the secondary iii through contact 98, switch arm 9?, thermostatic element @6, con= tact 99, contact 66, contact arm 67?, operating coil 02, hot contacts 56 and 65, thermostatic element 6%, and contact it)?! back to the secondary iii. Completion of this running circuit shunts out the heating element its oi the safety switch 6% which maintains the relay energized and hence the hurner motor tilt running. Since contact 50 engages contact 55 before contact 36 disengages contact 65, the circuits throughthe operating coil $2 of the relay are not interrupted and continuous'action is assured.

At substantially the same time the contact moves out oi engagement with the contact (it, the c means 89 releases the pin 88 to cause the "contact arm to move out of engagement paratus wherein only a single ignition switch is utilized for turning on and turning oil the igni= tion means at predetermined points in the cycle of operation oi the oil burner apparatus, wherein the ignition switch is operated primarily by the relay which has a relatively unlimited amount of power, and wherein the ignition switch is opened by the combustion responsive device by merely tripping a latchwith a minimum amount of effort.

Although for purposes of illustration I have shown one form of this invention, other forms thereof may become apparent to those skilled in the art upon reference to this disclosure and therefore this invention is to be limited only by the scope of the appended claims and prior art.

I claim as my invention:

1. In a control system for an oil burner apparatus having burner means and ignition means, the combination of, a relay having a burner switch operatively associated with the burner means and an operating coil to close the burner switch when energized for operating the burner means, an ignition switch comprising a stationary contact and a movable contact operatively associated with the ignition means, a member operated by the relay coil of the relay, a direct mechanical connection between the member and the movable contact of the ignition switch, biasing means included in the connection for biasing the movable contact of the ignition switch to an open position, an abutment member carried by the movable contact of the'ignition switch, cam means engaging the abutment member and operating to overcome the biasing means so that the ignition switch is closed upon energization of-the operating coil of the relay, and means operated as an incident to establishment of com-- bustion for operating the cam means to disengage the cam means and the abutment member whereupon said biasing means opens the ignition switch to stop operation of the ignition means.

2. A switching means for controlling the operation of an ignition means of an oil burner apparatus, comprising in combination, an electromagnet, a member operated thereby, a switch comprising a stationary contact and a movable contact, a resilient connection between the member and the movable contact of the switch, latch the stop.

5. In combination, aswitch having a stationary contact and a movable contact, an electromagnet, a member operated by the electromagnet, a resilient connection'bet'ween the member and the movable contact of the switch acting to open the switch, latch means associated with the resilient connection to maintain the same rela- Y tively rigid, the arrangement being such that the switch is closed and opened upon energization and deenergization of the electromagnet, condition responsive means, and means including a slip friction connection between the condition responsive means and the latch means for releasing the latch means when the condition has changed a predetermined amount to allow the resilient connection to open the switch.

6. A control system for a fuel burning device, comprising in combination, electrical fuel feed control means, means for igniting the fuel, a first switch in control of said fuel feed control means, a second switch in control of said ignition means, means for simultaneously closing ,said first and second switches, a connection between said last named means and said second switch, said connection requiring support in order to render it operative to close said second switch, and combustion responsive means providing such support in the absence of combustion and for mechanically removing said support to permit said second switch to open upon the establishment of combustion, and slip friction means between said combustion responsive means and said support;

means associated with the resilient connection 7. An ignition control for a fuel burner com prising in combination, a biased open ignition switch, an electromagnet, connections between said electromagnet and said switch, a stop having a first position in which it cooperates with said switch to render it capable of being closed by said electromagnet and connections-upon enerfor releasing the latch means to cause the resil.-

ient connection to open the switch contacts for stopping operation of the ignition means. i

3. In combination, a switch comprising a stationary contact and a movable contact, an electromagnet, a member operated by the electromagnet, a resilient connection between the member and the movable contact of the switch acting to open the switch, latch means associated with the resilient connection to maintain the same relatively rigid,.the arrangement being such that the switch is closed and opened upon energization and deenergization of the electromagnet, and condition responsive means for releasing the latch means to allow the resilient connection to open the switch. 4. In combination, a movable contact arm, a stationary contact on one side of the arm and adapted to be-engaged thereby, a stop on the other side of the arm and adapted tobe engaged thereby, resilient means for biasing the movable contact arm away from the stationary contact toward the stop, an electromagnet, a member operated thereby, a pivotal connection between the member and the movable contact arm, releasable means for overcoming the resilient means and for holding the arm and member relatively fixed with respect to each other so that gization of said electromagnet, and combustion responsive means for mechanically removing said stop to permit said switch to open due to its bias, and slip friction means between said combustion responsive means and said stop.

8. A control system for fuel burners comprising in combination, an electrical fuel feeding device, a control switch therefor, an ignition device, a biased open ignition'switch therefor in cluding a movably mounted switch arm, an abutment member having a first position in which it restricts the movement of one portion of said arm, a relay for simultaneously closing said switches, the closing of said ignition switch being dependent upon the abutment member being in said first position to restrict the movement ing in combination, an electrical fuel feeding device, a control switch therefor, an ignition device, an ignition switch comprising a first contact and a movable contact carrying arm biased to open position, a relay for simultaneously closarm and permit it to move ing said control switch and ignition, switch, an abutment, a portion of said movable contact arm reacting against said abutment to overcome the effect of said bias and render said relay operative to close said ignition switch, a thermal element responsive to combustion, and mechanical connections between said thermal element and abutment whereby said abutment is moved directly by the force developed in said thermal element as a result of the establishment of combustion to move said abutment and release said movable contact to open contact position under the influence of its bias.

10. A control system for a fuel burning device comprising in combination, electrical fuel feed control means, means for igniting the fuel, a first switch, said fuel feed control means being under the sole control of saidflrst switch, a second switch in control of said ignition means, an electromagnet for closing saidfirst and second switches, a thermal safety switch, a heater therefor, a thermal element responsive to combustion of the fuel, hot and cold switches mechanically actuated by said combustion responsive element, a main switch closing a circuit including said safety switch, the heater therefor, the cold combustion switch and the electromagnet, said electromagnet closing said first and second switches to initiate combustion, said combustion respon- 5 sive element first closing said hot switch to shunt the safety switch heater and then opening said cold switch, and mechanical connections between said element and second switch for tripping said second switch to open position, said combustion responsive element first opening said hot switch following a flame failure to deenergize the electromagnet and shut the system down and then reclose the cold switch to cause the system to recycle.

11. A control system for fuel burners comprising in combination, an electrical fuel feeding device, a control switch therefor, an ignition device, an ignition switch comprising a first contact and a movable contact carrying arm biased to open position, a relay for simultaneously closing said control switch and ignition switch, an abutment, a portion of said movable contact arm reacting against said abutment to overcome the efiect of said bigs and render said relay operative to close said ignition switch, and thermal means rendered active for automatically moving said abutment to release said movable contact arm and permit it to move to open contact position under the influence of its bias after said electrical fuel feeding device has been energized and combustion established.

LAUREN V. SODERHOLM.

Images