US1921196A - Burner control apparatus - Google Patents

Description

A 8- 1933- J. PQKRIECHBAUM 1,921,196

BURNER CONTROL APPARATUS {filed July 18, 1931 2 Sheets-Sheet l INVENTOR JOHN P KRIECHBAUM ATTORNEYS BURNER CONTROL APPARATUS Filed July 18, 1931 2 Sheets-Sheet 2 HOT LINE J eraouruo ms INVENTOR JOHN P. KRIECHBAUM s V Y flfi gmrv-q ATTOHNE Y6 Patented Aug. 8, 1933 um'rso STATES PATENT OFFICE I BURNER CONTROL APPARATUS of Delaware Application July 18, 1931. Serial No. 551,700

6 Claims.

switch for rendering the system inoperative if flame is not produced at the end of a predetermined timed period, and having means for continuing fuel feeder operation after ignition, and also having a combustion responsive device.

An important object is to utilize the latter device to time the de-energization of a post-ignition period by delaying the opening of a contact, which contact must be closed in order to start the apparatus at all.

It frequently happens that although flame is produced, it more or less promptly fails, because ignition has not been continued long enough to maintain the flame until the refractory surfaces are warm enough to make the flame selfsupporting. The result is a shut-down of the entire apparatus by the safety switch, and often a cold dwelling over a long period until after repair or adjustment of the apparatus.

It is, therefore, an important object of this invention to cause ignition to be maintained after flame is produced, for a timed period and to control this timing period by means of a flame responsive device. As will later appear, the timing period of the combustion responsive device is well within the timing period for which the safety switch is set.

Important objects are to use the normally closed contact of the combustion responsive device as a timer to continue ignition after flame is produced; to open this contact only after the apparatus is conditioned to sustain combustion; and to utilize the opening of a cold contact for the above purposes, as distinguished from the making of a hot contact.

Features of the invention include all the details of this embodiment of the invention as shown, along with the broader ideas of means disclosed.

Objects, features and advantages of the invention will be set forth in the description of the drawings forming a part of this application, and in said drawings Figure 1 is a vertical longitudinal section through the stack switch, and the mechanisms for controlling its contacts;

Figure 2 is an elevation showing the parts positioned as before application of heat to the thermostatic element; and

Figure 3 is a diagram illustrating the system.

The principal elements of this embodiment tached to the shaft 34 is the usual thermostatic of the invention are: two relays, or their equivalents, designated No. 1 and No. 2, (also referred to as first and second); an igniter 1 and a fuel feeder 2, simultaneously energizable when the first relay closes; a safety switch 3 which is adapted when opened to render the entire system inoperative; a heating element 4 for timing the opening of the switch (a warp switch is ordinarily used); a room thermostat having a movable element R adapted to control contacts W-B in this instance sequentially; a flame or combustion'responsive device (stack thermostat) generally indicated at 6, having contacts 7'8,

which are overlappingly controlled on rise in temperature and non-overlappingly controlled on fall in temperature, the contact '7 being normally closed when flame is absent, and the contact 8 being normally opened under the same conditions.

Relay No. 1 may be said to constitute ignition and motor controlling means and relay No. 2 may be considered means for separately controlling the motor or fuel feeder, to continue fuel feed after de-activation of the igniter by relay No. 1. Various electrical connections are pro- 30 vided, including contacts controlled by the relays. Relay No. 1 controls contacts 10, 11, 12 and 13, and relay No. 2 controls contacts 1415. The circuit connections are not now described in detail but are referred to more particularly under the heading operation.

The combustion-responsive switch-controlling device generally designated 6, and now to be described, essentially consists of first and second contacts 7--8, a movable member responsive to temperature changes, and means controlled by the movable member for controlling the contacts.

The numeral 30 indicates a suitable casing for housing the switches and part of the means for operating them. Numeral 31 indicates the cover. Suitably attached atthe back of the casing is a tubular member 32 which is adapted to pass through the wall of the stack and is suitably secured to this wall by means of a bracket 33. Within the tubular member is a shaft 34 suitably journaled as at 35 at one end of the tube and journaled at the opposite end as at 36 in the rear wall of the casing. At-

element 37 which herein has the form of a spiral ribbon having one end connected as at 38 to the tube 32 and having the other end connected as at 39 to the shaft 34. On temperature change, the rod is reversely rotated according to the direction of change. Mounted upon the shaft within the casing are switch control elements which primarily consist of two spur gears or toothed disks which cooperate with the movable duced portion and abutting the shoulder is a bushing 43. The bushing is suitably fixed to the shaft by means of end pressure by parts later described. Arranged also on the reduced portion is a sleeve 45 of insulating material which abuts the bushing 43 and upon this insulating sleeve is a cup-shaped insulating member 46 which also abuts the bushing 43 and caps it. Also mounted on the insulating sleeve is a toothed disk 47, and on the insulating sleeve is also mounted a sleeve 48 which abuts the disk 47. The sleeve 48 has a reduced' portion 50 forming a shoulder 51 and upon this reduced portion is rotatably mounted another toothed disk 52 which abuts the shoulder 51. This disk is slotted as at 53, see Figure 2, the slot also being curved and having the center of 3 curvature on the axis of the shaft 34. Against the outer face of this disk is arranged a slotted plate 55, the slot 56 of which registers with the slot 53 of the disk. This plate swings on the reduced portion and a set screw 57 secures the plate in. any adjusted position. The plate is segmental and covers only a portion of the face of the disk and provides at one side a radial portion 58 as a stop. Disk 47 carries a pin 60 which passes loosely through the slot 53 of the disk 52. That portion of the slot 53 between the stop 58 and the end 61 of the slot provides a lost motion connection between the fixed disk 47 and the movable disk 52. The degree of lost motion can be varied, or both disks can be made to rotate in unison in fixed relation to the shaft 34. On counter-clockwise motion of the shaft 34, the disk 47 moves a certain distance before the pin 60 engages the end 61 of the slot 53. The purpose is to cause one of the contacts to open only after a predetermined rotation of the shaft 34 has occurred and after the other contact has closed. This is more thoroughly explained under the heading operation.

Mounted on the insulating sleeve 45 is a washer 63 which prevents undue axial motion of the disk 52 and stop plate 55. Also carried by the element 45, and abutting washer 63, is a cup 64 similar to the cup 46 previously mentioned. The inner surface of cup 64 lies in a plane beyond that of the sleeve 45. Within the cup and engaging its inner surface is another washer 65, and engaged with this washer is a split washer 66. A nut 67 clampingly engages the split washer to secure the elements and to clamp the disk 47 by transmission of clamping pressure through washers 66-65, cup 64, washer 63, sleeve 48, disk 47, cup 46, bushing 43 and shoulder 42. It is obvious that other suitable means may be used for fixing the disk 47 for rotation with the shaft 34, and for mounting the disk 52 for rotation relative to said shaft and to the other disk, and

for suitably insulating the disks from the shaft.

Suitably attached within the casing 30 is a block of insulating material 68, and to this block are attached, see Figure 2, two plates respectively indicated 6970. Upon the plate 69 is mounted a flexible contact arm 71 "cold contact), and upon the plate 70 is mounted a flexible contact arm 72 (hot contact). Suitably secured to a common support 73, in turn mounted on the insulating block, is a flexible contact arm 74 having a contact stud 75 engageable with the corresponding stud of the arm 72 to close the circuit. The arm 74 is biased to move automatically to closed circuit position. Associated with the arm 74 is a flexible control arm 76 the terminal of which engages with the teeth of the disk 47. This control arm is connected at one end to support 73. Figure 2 shows the parts positioned as when contact arms 72-74 are in circuit open position. The control arm 76 engages the arm 74 and springs it to the position shown, from which position the arm will automatically follow the control element 76 when the disc 47 moves in counter-clockwise direction. The stud '75 of arm 74 passes loosely through an opening 82 of the control arm 76 as shown in Figure 1. On counter-clockwise rotation of the disk 47, arm 74 follows the control arm 76 until the contact 75 closes with arm 72 (hot contact closed, see 8, Figure 3), after which the control arm 76 can move away from the switch arm on continued rotation of the disk 47 in the same direction, in this instance as the temperature continues to rise. During continued motion in counter-clockwise direction the control arm 76 is successively released and moves against the following tooth as a stop, but without suflicient movement to permit the arm 76 to move the switch arm 74.

Attached to the support is an extension 79 having a portion to which is attached a spring metal arm 77 bent intermediately to provide a cam 78, in this instance convex toward the shaft and toward the free end of the switch arm, and providing a peak and inclined planes, one at each opposite side of the peak. To the support 73 is also attached a spring contact arm which has a contact stud engageable with the contact arm 71. The arm 80 is also biased to move to circuit closed position, and its outer end is engaged by the teeth of the disk 52, and the arm 80 has an opening 81 through which the spring arm 77 passes. When the arm 80 is in switch closed position, its terminal is disposed at the left side of the cam 78, and when in switch open position, at the opposite side. In either position, the cam 78 acts as a stop for the arm. On movement of the arm 80 in either direction from stop position, the spring arm 77 is flexed and tensioned. As the arm 80 rides over the peak of the cam 78 and after it has reached a position slightly to one side, the action of the spring 77 forces one of the inclined planes against the side of the opening 81 of the arm 80 to accelerate arm motion in a corresponding direction. The switch arm 80 may or may not be biased.

At least one of the screws 85 of the plate 69 is connected by a conductor 86 with the binding post 87, the element being embedded in the insulation. At least one of the screws 88 of the plate 70 is connected by embedded conductor 90 with the binding post 91. The screws 92 are connected by the bar 93 with the binding screw 94.

Operation of combustion responsive device Referring to Figure 2: Assume the rotation of the shaft to take place in counter-clockwise direction due to a rise in temperature. During the first part of this rotation the lost motion connection (stops 586l) between the disks permits of movement of the fixed disk 47 without movement of the other. Disk 52 is held against movement by the switch arm 80. The control member 76 now moves to the right and switch arm 74 follows, until it reaches switch closed position. After this closure, the pin 60 which has been traveling in the slot 53 engages the shoulder 61 and on continued motion of the shaft in counter-clockwise direction, the disk 52- shaft rotation is reversed, and is clockwise.

During the forepart of this motion, the disk 52 is held against rotation as the result of engagement of its teeth with the arm 80 resting against the right side of the cam, acting as a stop. The first action is by the disk 47 which moves the control member 76 against the switch arm 74 and moves contact 75 away from the contact arm 72. During this movement the pin 60 is moving in the slot in a direction away from the stop 61 formed by the end of the slot. After a timed interval determined by the stop spacing, the pin engages the stop 58 and the disk 52 also begins to rotate in clockwise direction, resulting in movement of the switch arm against the cam, again depressing the spring arm 77,'and finally so positioning the arm 80 that the cam acts to snap it to switch closed position. It will be noted that although the switch may be biased to move to one of its positions, cam action accelerates the movement.

Operation of system Assume that the combustion responsive device is cold '(70' for example) and that contact 7 is closed and contact 8 open. Now assume a closure of the room thermostat at W, R, B, on a call for heat. The first action is to energize theigniter and fuel feeder as well as the heater element of the thermal safety switch. The circuit is as follows: from one side of the secondary of transformer 16, safety switch 3, W, R, B, conductor l7, heater 4, coil 18 of the first relay, contact 7 of the combustion responsive device (or stack thermostat) conductor 19 to opposite side of the secondary. Closure of the relay closes first and second contacts 10, 11, as well as igniter and motor contacts 12 and 13. Closure of contact 10 establishes a holding circuit for the first relay as follows: one side of the secondary, 3, W, R, 20, contact 10, conductor 21, 4, 18, cold contact 7, conductor 19 to the opposite side of the transformer. Closure of contact 12 establishes a circuit to the fuel feeder as follows: hot line, 22, 12, 23, fuel feeder 2 to ground line. Closure of contact 13 establishes the following circuit to the igniter: hot line 22, 12, 13, 24, igniter, to ground. It will now be assumed that combustion is successful and that the contact 8 of the combustion responsive device closes at the end of about ten seconds. Closure of contact 8 energizes the second relay,

and closes a second circuit to the fuel feeder, to continue fuel feeder activation after the first relay is opened, .which relay tie-energizes the igniter and breaks the first fuel feeder circuit by opening of contacts 12 and 13. The circuit for energization of the second relay is as follows: transformer, safety switch 3, W, R, 20, 10, 25, 11, 26, coil 27 of the second relay, hot" contact 8, conductor 19 to the opposite side of the transformer secondary. It will be noted that although contact8 has been closed contact 7 is also closed and relay No. 1 remains energized as well as the heater 4 of the time switch and the igniter. The mechanism which controls the contacts 7 and 8 may be adjusted and controlled so that contact 7 will open (for example). only in \about thirty to forty-five seconds after the contact 8 has closed. This timing period is well within the timing period for which the safety switch 3 is set, which period will be assumed herein to be two minutes. Therefore, even after successful combustion, energization of the igniter and heater 4 is maintained. This postignition period of igniter operation is valuable because it sometimes happens that, although combustion is successful, it hasnot continued for a sufficient length of time and the temperature has not been sufficiently raised to assure its continuance. By continuing ignition, the continuance of combustion ismore likely to accrue.

It is one of the salient features of this invention that the total timing period for post-ignition iscontrolled by the cold contact 7 of a combustion responsive device or stack thermostat, as distinguished from warp switches or other circuit breaking timers. It will be noted that the timing period continues as long as the contact 7 is closed, and that this closure continues for a time after combustion is' established in order to insure continued combustion. It has heretofore been the practice to discontinue ignition substantially immediately after production of flame, with the disadvantage that if ignition is not properly established there is a shut-down of the entire apparatus merely because the igniter has not continued a sufficient length of time to maintain a weak flame. The result was unnecessary safety shut-down, and often a cold house over a long period until after repair or re-adjustment of the apparatus.

Insofar as I am aware, no one has before used a cumbustion responsive device to time de-energization of a post-ignition period by delaying the opening of a contact which must be closed to start the apparatus at all, nor in which the contact maintains timer switch operation until opened, at the end of a timed period which is less than the timing period of the timer switch. In the devices known to me, some auxiliary timer device or switch is used, or motor switching systems are used.

It is to be noted that in this control, the energizing circuit for No. 1 relay has therein in series the heater coil, and the thermal safety switch, as well as the cold contact 7 of the combustion responsive device so that in 'case of short-circuiting of this cold contact, current will be maintained through the heating element of the safety switch until the safety switch trips. In other words, there is herein provided a very simple and cheap method of testing the cold contact 7 of the combustion responsive device and also for testing the wiring of this device. If combustion is not produced, No. 1 relay will remain closed for a period of time which is controlled by the thermal safety switch and the entire apparatus will then be rendered. inoperative.

In case all of the contacts of the combustion responsive device are short-circuited, No. 1 relay will be energized and immediately No. 2 will be energized. Under this condition flame could be produced and normal operation could continue until the end of the safety period, at which time a shut-down will occur. If the "cold contact 7 is shorted, fiame could be produced and a normal operation could continue until the end of the safety period when shut-down would occur.

I claim as my invention:

1. A system of the class described comprising an igniter, a fuel feeder, a safety timer for rendering the system inoperative if not de-energized at the end of a predetermined timed period, first electromagnetic means operative when energized, and which must be energized, to energize the igniter, fuel feeder and timer, second electromagnetic means operative when energized to continue fuel feeder energization after ignition, first and second contacts and means for controlling them comformably to combustion conditions to have the first initially closed when combustion does not exist, to have the second close promptly on production of combustion, and have the first open at the end of a time period after the second closes, and circuits controlled by the contacts to permit energization of the timer and first electromagnetic means while the first contact is closed, to obtain energization of the second electromagnetic means when the second contact closes, and to de-energize the timer and first electromagnetic means on opening of the first contact, and on temperature fall due to cessation of combustion to delay closure of the first contact for a time period after opening of the second contact.

2. A system of the class described including a room thermostat, an igniter, a fuel feeder, a first relay operable when energized to energize the igniter and fuel feeder and to close a contact, a second relay operable when energized to separately energize said fuel feeder and to close a contact, a thermal timing switch operable when energized to render the device inoperative if combustion is not produced at the end of a predetermined timed period and having a heater, a combustion responsive device having first and second contacts, means by which said contacts are controlled by said combustion responsive device to have the first closed and the second open when combustion does not exist, to close said second contact promptly and thereafter open the first contact at the end of a time period after production of combustion, and to cause the second to open promptly and the first thereafter to close at the end of a time period on cessation of combustion, a starting circuit for the first relay including therein said timing switch, room thermostat, heater, first relay and the first contact of said combustion responsive device, a starting circuit for said second relay including therein said thermostat, contact of the first relay, said second relay and the second contact of the combustion responsive device, and a holding circuit for the second relay including said thermostat, contact of said second relay, said second relay, and second contact of said combustionresponsive device.

3. A system of the class described comprising an igniter, a fuel feeder, first electromagnetic means operative when energized, and which must be energized to energize the igniter, and fuel feeder, second electromagnetic means operative when energized to continue fuel feeder energization after ignition, first and second contacts and means for controlling them conformably to combustion conditions to have the first initially closed when combustion does not exist, to have the second close promptly on production of combustion, and have the first open at the end of a time period after the second closes, and circuits controlled by the contacts to permit energization of the first electromagnetic means while the first contact is closed, to obtain energization of the second means when the second electromagnetic contact closes, and to de-energize the first electromagnetic means on opening of the first contact, and on temperature fall due to cessation of combustion to delay closure of the first contact for a time period after opening of the second contact.

4. A system of the class described comprising an igniter, a fuel feeder, first electromagnetic means operative when energized, and which must be energized to energize the igniter and fuel feeder, second electromagnetic means operative when energized to continue fuel feeder energization after ignition, a combustion responsive device having first and second contacts, and means for overlappingly controlling them on initial temperature rise to close the second before the first opens, for non-overlappingly controlling them on temperature fall to close the first after the second opens, and circuits controlled by the contacts to permit energization of the first electromagnetic means while the first contact is closed, to obtain energization of the second electromagnetic means when the second contact closes, and to de-energize the first electromagnetic means on opening of the first contact, and on temperature fall due to cessation of combustion to first de-energize the second electromagnetic means and then permit energization of the first electromagnetic means.

5. A system of the class described, comprising, in combination, a main switch, a fuel supply controller, first electromagnetic means operative when energized to operate said fuel controller to supply fuel, a switch closed by said first electromagnetic means when energized, a second electromagnetic means operative when energized to continue the supply of fuel, a switch closed by the second electromagnetic means when energized, a combustion responsive device having first and second contacts, means by which said contacts are controlled by said combustion responsive device to have the first closed and the second open when combustion is absent, to close said second contact promptly and thereafter open the first contact upon production of combustion, and to cause the second contact to open promptly and the first to close at the end of a time period on cessation of combustion, a starting circuit for the first electromagnetic means including therein said main switch, first electromagnetic means and the first contact of the combustion responsive device, a starting circuit for the second electromagnetic means including therein said main switch, the switch 14; controlled by the first electromagnetic means and the second contact of the combustion responsive device, and a holding circuit for the second electromagnetic means including the main switch, the switch controlled by the secand electromagnetic means and the second contact of the combustion responsive device.

6. A system of the class described, comprising, in combination, a main switch, a high voltage fuel supply controller, first electromagnetic means operative when energized to energize said fuel controller, a switch closed by said first electromagnetic means when energized, a second electromagnetic means operative when energized to continue energization of the fuel supply controller, a switch moved to closed position by said second electromagnetic means when energized, a combustion responsive device having first and second contacts, means by which said contacts are controlled by said combustion responsive device to have the first closed and the second open when combustion is absent, to close said second contact promptly and thereafter open the first contact upon production of combustion, and to cause the second contact to open promptly and the first to close at the end of a time period on cessation of combustion, a low voltage starting circuit for the first electromagnetic means including therein said main switch, first electromagnetic means and the first contact of the combustion responsive device, a low voltage starting circuit for said second electromagnetic means including therein said main switch, the switch controlled by the first electromagnetic means and the second contact of the combustion responsive device, and a low voltage holding circuit for the second electromagnetic means including the main switch, the switch controlled by the second electromagnetic means and the second contact of the combustion responsive device.

J OHN P. KRIECHBAUM.

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