US2727203A

US2727203A - Smoke detector and blower motor control system

Info

Publication number: US2727203A
Application number: US227046A
Authority: US
Inventors: Edward J Zeitlin; Herbert S Thorn; Lee R Leighton
Original assignee: Heat Timer Corp
Current assignee: Heat Timer Corp
Priority date: 1951-05-18
Filing date: 1951-05-18
Publication date: 1955-12-13
Anticipated expiration: 1972-12-13

Description

United States Patent SMOKE DETECTOR AND BLOWER MOTOR CONTROL SYSTEM Edward J. Zeitlin, Yorktown, Herbert S. Thorn, Flushing, and Lee R. Leighton, Mohegan Lake, N. Y., assigners to Heat Timer Corporation, New York, N. Y.

Application May 18, 1951, Serial No. 227,046

Claims. (Cl. 318-480) In other words, it provides for an automatic indication resulting from the system being affected by a temporary smoke condition, but permits the system to reset before the burner is shut down.

In general the system comprises means for producing a beam of light that is directed to a photo-electric element of the photoemissive type. The light means being positioned on one side of a chimney flue and the photoelectric element on the opposite side so that the flue gases must pass through the light beam. In addition there are provided means connecting said photo-electric element to an electronic control. The electronic control includes a thyratron tube which in turn controls the energization or de-energization of a relay. The relay in turn controls the closing and opening of a plurality of circuits, one of these circuits includes a timing motor, and a switch operating cam driven by said motor. The thyratron tube is used to control the operation of the relay and functions as follows: the tube has two voltages impressed on its grid, one from the photo-cell and one from an auxiliary source which in this instance is controlled by a potentiometer connected across the filament circuit. When there is a clear condition or no smoke, the photo-cell is illuminated and current flows from the photo-cell and causes a voltage to be impressed on the grid in such a manner to change the characteristic of the tube and become conductive. With the tube in a conductive condition, the circuit connected to the tube, that is, the circuit between the anode and the cathode will convey a current to the relay to energize same andv vice versa when the photo-cell is not illuminated due to a smoke condition, the thyratron will become non-conductive and the energizing circuit will be broken. The relay controls the switch contacts associated therewith to close predetermined circuits, one of which includes the timing motor. When this circuit is closed by the relay the motor will be operated and will rotate a switch cam mounted on said motor shaft, the cam in this instance making one revolution in a two minute interval. A pair of switches are mounted to contact said cam, one of said switches providing a holding circuit to retain the timing motor connected to a source of potential until the cam has completed one revolution, the other switch which.

is a gang switch will be closed during the rotation of the cam and is the means of holding the burner circuit closed untilthe cam completes a predetermined portion of its cyclewhen the switch will open.

It is an object of this invention to provide a smoke detecting system that will accomplish the above mentioned results and must be unusually sensitive and reliable for automatic operation, to prevent false alarms or unnecessary shut downs of the burner motor.

A further object of this invention is to provide a lightsensitive smoke detecting system for chimneys that will produce an alarm signal when smoke is detected and will at the same time initiate a timed burner shut-oft mechanism.

A still further object of this invention is to provide a light sensitive smoke detecting system which includes an electronic control that may become non-conductive with the presence of smoke to in turn de-energize the relayand initiate the operation of a timer burner motor shutoff, but in addition provides means to reestablish the burner motor circuit in the event the smoke con-' dition is dissipated before the timer has completed its cycle.

Another object of this invention is to provide a light sensitive smoke detecting system for chimneys to produce an alarm signal indicating the presence of smoke, to initiate a timed motor burner shut-off and to provide means to re-establish the operation of the burner includes a chimney 10 with a flue 11. The chimney isprovided with a pair of opposed apertures or

ports

12 and 14. Into port 12 there is inserted a light source 15 which may, as in this instance be a watt volt incandescent lamp 16 that is oriented so that its light will fall upon the opposite aperture 14. Into the aperture or port 14 there is mounted a phototube 17 which is simply a device of variable conductance in response to incident light. A circuit is connected to both the light source 15 and the phototube 17 and includes a positivegrid control thyratron tube 20 which is in turn connected to a relay 22, that is, the lead 50 connects the anode or plate of the tube with one side of the relay 22. The relay 22 on its opposite end is connected to switch 36 and to the opposite power lead 25. Relay 22 is provided with In its open position as illustrated,

a contact arm 41. the relay is de-energized. Contact arm 41 is mechanically connected to a pair of contact arms 42 and 45, thus the

arms

41, 42 and 45 will operate in unison. There are provided a pair of switches 43 and 44 positioned either side of contact arm 41 and a pair of switches 47, and 48 positioned either side of contact arm 42, while a single switch 46 is positioned adjacent to contact arm 45. Contact arm 41 in its open position retains switches 43 and 48 closed while switches 44, 46 and 47 will remain open until the relay is energized. Therefore when the relay is energized, switches 44, 46 and 47 will be closed. ;A source of potential (115 volt A. C.) is provided and connected to the apparatus by means of feed lines 25 and 26. A line switch 27 is provided in feed line 25. A oneone-half R. P. M. or one revolution in two minutes. A

cam 30 is afiixed to shaft 29 to be driven or rotated thereby.

Cam 30 is provided with one cut-out segment 31 in its periphery 32. Mounted adjacent to the periphery 32 of the cam 30 are a pair of switches 33 and '34 that bear Patented Dec. 13, 1955 The motor 28 has a drive shaft 29 which will be driven at the rate of' on the periphery of the cam and are normally in a closed relation, but will drop to an open relationship when the cutout segment is moved into an adjacent position as illustrated with switch 33. Switch 34 is a gang switch comprised of three

switches

35, 36 and 37 all operated in a mechanically connected relationship to be closed or opened in unison. A burner motor 40 is provided as the object that is to be controlled by the apparatus and circuit herein described. Burner motor 40 is connected to the source of potential 26, and 27 but in series with switch 46 of the relay 22 as well as in series with the switch 35 of the gang switch 34. The burner motor 40 is also provided with a standard recycling circuit 31 to be described in detail hereafter. The recycling circuit includes a relay 8, a bimetal recycling contactor bar and a gang switch 1, 2 and 3 operated by relay 8. The circuit between components may be followed by reference to the drawing. Motor 40 is connected on one side by means of lead 80 to the power line 25 and on the opposite side is connected by means of lead X to switch 2. When relay 8 is energized switches 1, 2 and 3 will be closed and the motor circuit from switch 2 will be connected through lead C to the other side 26 of the power line. When the line switch 27 is closed and relay 22 becomes energized, switch 46 will be closed and of course switch 36 is normally closed, thus a circuit from line 25 through lead 80 to line 81, through switch 46, through lead 82, through bimetal contact 4, through lead 7, through relay 3, through lead 6 to the opposite side 26 of the power line will be completed. Relay 8 is thus energized closing contacts 1, 2 and 3. Contact 2 starts the burner motor as described. Contact 3 applies line voltage to the bimetal contact winding causing it to heat and thus open this contact 4, although the bimetal switch opens without delay when heated, it takes approximately 90 seconds for the bimetal switch to cool and remake the contact. Contact 1 is already closed thus shunting the contact 4 circuit, that is, the lead 82 is connected to contact 1 and when closed the circuit will flow through lead 7 and through relay 8 to lead 6 and to opposite side of the line 26, thus retaining relay 8 energized. The thyratron tube has its filament 60 connected on one side to the lamp 16 while the opposite side of the filament is connected to the power line 26. The opposite side of lamp 16 is connected to the opposite side of the power line 25. A potentiometer 61 is connected across the filament circuit and the potentiometer is also connected by a lead 62 to a resistance 63 which is in turn connected to the grid of the tube. This provides one circuit to permit impressing one voltage on the grid of the tube while the phototube 17 is connected by a lead 64 to a common lead 65 which in turn is connected to the power line and the opposite side of the phototube 17 is connected by a lead 66 to the grid of the thyratron to provide the means to adjust the grid of tube 20s potential with respect to the cathode 4A grid circuit making the thyratron conductive. Switch 48 of relay 22 is connected by means of a lead 70 to a terminal 71. The opposite terminal 72 is connected to a ground and a lamp 73 is shunted across the two terminals. An alarm (not shown) may be connected to these terminals 71 and 72 to be energized when switch 48 is closed as illustrated in the drawing. A by-pass switch 75 is also provided. The by-pass switch 75 will short out both switches and 46, since it is positioned across the two leads to

switches

35 and 46. Thus the switch 75 may be closed to in turn close the burner motor circuit. There is also provided a reset switch 54 which in an open position permits manual control of the apparatus, while in a closed position permits the control to operate automatically. In a closed position, switch 54 will complete two circuits, one starting with switch 37 which is connected to one side of a contact arm A of switch 54 to thus short out switch 37. The other circuit is closed by a contact arm B of switch 54 completing a circuit that shorts "out switch 36.

The operation of the device may be understood by reference to the drawing. It is first necessary that the line switch 27 be closed. This will in turn illuminate lamp 16 and provide a predetermined voltage on the filament of the thyratron tube 20. Assuming the chimney 11 to be clear of any smoke condition, the light rays of lamp 16 will fall upon the phototube 17 activating same. Thus the phototube 17 will impress a potential on the grid of the thyratron while the potentiometer 61 provides the means to adjust the grid of tube 20s potential with respect to the cathode for a grid circuit current corresponding to a certain illumination of phototube 17. Thus in this condition the thyratron becomes conductive and the power circuit from 26 will pass from the cathode of the thyratron to the anode and thus through lead 50 to relay 22 through the relay through lead 77 to the normally closed switch 38 passing out the opposite side of switch 36 to the leads which in turn connects to the opposite side of the power line 25. Thus relay 22 will be energized and when relay 22 is energized, contact arm 41 will be pulled downward thus closing switches 44, 46 and 47. The closing of switch 46 will close the power circuit to the burner motor 40, that is, the reset switch 31 of the burner motor is connected on one side by a lead 80 to the power line 25 and on its opposite side it is connected through contact switch 2 to the opposite side 26 of the power line. Thus the circuit to the burner motor is controlled by switch 46. The closing of switch 47 provides a holding circuit for relay 22, that is, with the thyratron in its conductive relation as above described, the circuit passing through relay 22 to energize same passes through lead 77 and through a lead 83 to the switch 47 which is closed when the relay 22 is energized. The circuit passes through the contact arm 42 through a lead 84 to lead 65 which as already described is connected to the opposite side 25 of the power line.

When relay 22 is de-energized due to a smoke condition, then contact 43 is closed, thus completing the circuit to the timing motor 8. The circuit is as follows: starting with power line 25 through lead 87 to motor 28, through lead 88, through lead 89 to switch 43, through the closed contact through lead to switch 37, through the closed contact to lead 76, through lead 76, through lead 90 back to the opposite power line. In the instance in which the smoke clears before cam 30 rotates to the position where arm 35A drops into notch 31, of course relay 22 will again be energized, opening contacts 43, however contact 33 in parallel with contact 43 maintains the circuit closed to the motor 28 and the cam will complete one revolution, until contact 33 is broken. If smoke continues and switch 54 is set in an open position for manual reset, then

contacts

35, 36 and 37 are open. Opening contact 35 will break burner motor circuit. Contact 36 will lock out relay 22, thus relay 22 cannot be reenergized and the burner motor will remain off until switch 54 is momentarily closed (manually). Contact 37 will open the circuit to the timing motor 28 so that contact arm 35 will rest in notch 31 until switch 54 is momentarily closed (manually), when motor 28 will restart and rotate cam 30 until contact 33 is opened by notch 31. If smoke continues and switch 54 is closed (the automatic reset position), when arm 35 drops into notch 31 then contact 35 opens shutting off burner motor, however, contact 36 is shunted by arm B of switch 54, and contact 37 is shunted by arm A of switch 54, therefore the cam 30 will continue its revolution until contact 33 stops motor 28. Of course the smoke condition in chimney is the main reason for de-energizing relay 22, but if this condition is eliminated before the (90 second) bimetal recycling time has elapsed, the relay 22 will again be energized and at the end of the 90 second cycle the circuit to relay 8 will again be completed and the control circuit will thus automatically restart the burner motor 40. Any failure in the circuit, such as the failure of the thyratron to function would of course cause the relay 22 to become de-energized and contact 48 would be closed thus sounding the alarm (not shown) that may be connected to terminals 71 and 72 and the circuit must be repaired before the relay 22 will again function properly.

This alarm circuit may be followed starting with the power line 25 through line 65, through closed switch 48, through line 70 to alarm terminal 71. Since the alarm is grounded on the opposite terminal 72 and the opposite power line 26 is also grounded then a circuit will be completed to the alarm (not shown). Also the alarm lamp L will be illuminated. The alarm may be a bell or light or buzzer as desired.

In manual reset position, the burner motor is shut off and stays off and alarm continues to ring.

In automatic reset position the alarm rings when smoke develops, however the burner will not be shut 01? until arm 35 drops, this shuts off burner motor and stops smoke condition, relay 22 is re-energized and alarm stops. Burner motor remains off until recycling mechanism reestablishes circuit. After recycling time has elapsed the burner motor will start again, if smoke has cleared there is no alarm, if smoke continues, the alarm continues until timer breaks it again.

Although we have described the operation of this control unit with relation to a smoke detecting means to cause the burner to shut off, we may depart from this particular means without departing from the spirit of this invention and this invention shall be limited only by the appended claims.

What is claimed is:

1. An apparatus for detecting smoke in a chimney including a light source for producing a beam of light across the flue of said chimney, a phototube of variable conductance responsive to incident light from said beam, means for conducting a stream of burned gases from burner through said flue past said light beam, an electronic element such as a positive grid control thyratron responsive to voltage from said phototube, a potentiometer connected to the power line and connected to the electronic element, said electronic element responsive to the potential impressed by said phototube and means to adjust the grid of the thyratrons potential with respect to the cathode with said potentiometer to make said electronic element conductive and said electronic element responsive to an unbalance of said voltages to become non-conductive, a relay connected to said electronic element and normally energized by a circuit passing through said electronic element, a plurality of contacts on said relay, one of the contacts on said relay controlling the operation of a burner motor.

2. In a device according to claim 1 a timing motor connected to a second set of contacts on said relay to be controlled by said relay, a one-half R. P. M. cam connected to and driven by said timing motor, said cam provided with a notched out portion, a plurality of normally closed contacts opened by the rotation of said cam, means to start said timing motor after said burner motor has been shut off, means to retain said timing motor operating for a complete revolution of said cam, and means to reset said cam to its initial position ready for another cycle of operation.

3. An apparatus for detecting smoke in a chimney including a light source for producing a beam of light across the fiue of said chimney, a phototube of variable conductance responsive to incident light from said beam, means for conducting a stream of burned gases from a burner through said flue past said light beam, an electronic element such as a potential grid control thyratron responsive to voltage from said phototube, a potentiometer connected to the power line and connected to the electronic element, said electronic element responsive to the potential impressed by said phototube and means to adjust the grid of the thyratrons potential with respect to the cathode with said potentiometer to make said electronic element conductive and said electronic element responsive to an unbalance of said voltages to become non-conductive, a relay connected to said electronic element and normally energized by a circuit passing through said electronic element, a plurality of contacts on said relay, one of the contacts on said relay controlling the operation of a burner motor, a bi-metallic heat controlled reset circuit connected to said burner motor, said reset circuit when broken constructed so that it will reclose after a predetermined time interval, said reset circuit also connected to the burner control contact of said relay.

4. In a device according to claim 3 a timing motor connected to a second set of contacts on said relay to be controlled by said relay, a one-half R. P. M. cam connected to and driven by said timing motor, said cam provided with a notched out portion, a plurality of normally closed contacts opened by the rotation of said cam, means to start said timing motor after said burner motor has been shut off, means to retain said timing motor operating for a complete revolution of said cam, and means to reset said cam to its initial position ready for another cycle of operation.

5. An apparatus for detecting smoke in a chimney including a light source for producing a beam of light across the flue of said chimney, a phototube of variable conductance responsive to incident light from said beam, means for conducting a stream of burned gases from a burner through said flue past said light beam, an elec tronic element such as a positive grid control thyratron responsive to voltage from said phototube, a potentiometer connected to the power line and connected to the electronic element, said electronic element responsive to the potential impressed by said phototube and means to adjust the grid of the thyratrons potential with respect to the cathode with said potentiometer to make said electronic element conductive and said electronic element responsive to an unbalance of said voltages to become non-conductive, a relay connected to said electronic element and normally energized by a circuit passing through said electronic element, a plurality of contacts on said relay, one of the contacts on said relay controlling the operation of a burner motor, a timing motor connected to a second set of contacts on said relay to be controlled by said relay, a one-half R. P. M. cam connected to and driven by said timing motor, said cam provided with a notched out portion, a plurality of normally closed contacts opened by the rotation of said cam, a manual reset switch shunted across the contacts operated by said cam.

References Cited in the file of this patent UNITED STATES PATENTS 216; John Wiley & Sons, New York, 1949.