US3290027A - Control arrangement for gas fired dryer - Google Patents

Description

E. L. ALUMBAUGH CONTROL ARRANGEMENT FOR GAS FIRED DRYER 5 Sheets-Sheet 1 QM gay Dec. 6, 1966 Filed May 18, 1964 mm M10 Ink Is .w \wb 23k 5.

E. L. ALUMBAUGH CONTROL ARRANGEMENT FOR GAS FIRED DRYER Dec. 6, 1966 3 Sheets-Sheet 2 MAI/V Filed May 18, 1964 CONTROL BOX GAS SOLENOID EXHAUST L/M/f THfRMST/IT IWO TOR fi/enz ar ugefle l. Q/zmZZazg" Z Dec. 6, 1966 E. L. ALUMBAUGH 3,290,027

CONTROL ARRANGEMENT FOR GAS FIRED DRYER Filed May 18, 1964 5 Sheets-Sheet I5 wa of Eugene J. Qfzzmfiazg/g United States Patent 3,290,027 CONTROL ARRANGEMENT FIRED DRYER Eugene L. Alumbaugh, Watson, 111., assignor to Borg- Warner Corporation, Chicago, 111., a corporation of Illinois Filed May 18, 1964, Ser. No. 368,065 8 Claims. (Cl. 263-33) FOR GAS and subsequent closing of the door; cycling of an air fiow control, or cycling of a thermostatic control. In such case, the gas-air mixture, remaining in the burner, is ignited before reaching the burner ports and flashes back into the burner venturi.

It is the principal object of the present invention to provide an improved control system for a gas burner assembly of the type described which provides for a sufficient delay between the time the air movement begins and the burner is ignited to insure purging of the burner of unburned gas by the air flow to allow safe ignition.

Another object of the invention is to provide an electrical control system of the character described in which a gas supply valve is electrically-controlled by a time delay arrangement effective to instantaneously close the gas supply valve upon any interruption of power and, after a suitable period of time sufficient to insure air flow purging unburned gas from the burner, to open the valve.

Additional objects and advantages of the invention will become apparent from a consideration of the following specification taken in connection with the accompanying drawings, in which:

FIG. 1 is a side elevation of a laundry dryer embodying the improved control arrangement for the gas burner assembly thereof;

FIG. 2 is a vertical sectional view of the dryer, said section being taken on line 2-2 of FIG. 1;

FIG. 3 is a perspective view of the dryer, with the top wall removed;

FIG. 4 is a schematic illustration of the gas burner assembly and certain controls therefor; and

FIG. 5 is a circuit diagram of the control arrangement.

Referring to FIGS. 1, 2, and 3, the dryer comprises a cabinet generally indicated at and of box-like construction having top and bottom walls 11 and 12, side walls 13 and 14, and front and rear walls 15, 16. Rotatably mounted in a conventional manner withincabinet 10 is a drum 17 having a perforated cylindrical wall 18, a front wall 19 with a circular opening in alignment with an opening in cabinet wall and closed by cabinet door 20 for transferring clothing to and from the drum. The drum also comprises a rear wall 21, in the form of a disc, connected to a drive shaft 22 positioned at the rotational axis of the drum and journalled in a trunnion housing 23 supporting the drum for rotation on the rear wall 16 of the cabinet. Positioned beneath the drum 17 is a hood and lint screen assembly 24 supported on the rear cabinet wall 16. A fan or blower 25 is also positioned within the cabinet and adjacent the assembly 24, and is operatively connected to the drive shaft of a motor 26. The shaft of the motor 26 is connected by a pulley 27 forming a portion of a suitable speed reducing arrangement for rotating the drum 17 concurrently with opera- 3,290,027 Patented Dec. 6, 1966 tion of blower 25. This arrangement includes a belt 28 connecting pulley 27 to pulley 29 on an idler shaft 30 provided with a sprocket 31 connected by a roller chain 32 to a sprocket 33 fixed to the drum drive shaft 22.

A gas burner assembly is mounted in the upper portion of the cabinet and comprises burners 34, 34 within a housing 35 extending between and connected to the top wall 11 and a horizontal upper partition wall 36 of the cabinet. As shown in FIG. 2, operation of the blower 25 causes external air to flow through an opening in the cabinet top wall 11, an opening in housing wall 37 into the housing to be heated by the burners, the heated air passing through openings in housing wall 38 and cabinet partition wall 36 into and around drum 17, an opening in cabinet lower partition wall 39 and the lint screen assembly 24, to the fan 25, and thence through an opening in cabinet rear wall 16 to the atmosphere.

The gas burner assembly illustrated in FIGS. 1 and 4, is well known and is provided, in conventional manner, with a gas supply line 40 connected to the burners 34, 34 and also to a pilot burner 41 (FIG. 2) between the burners 34, 34. A valve 42 is operated by a solenoid 44 to control the flow of gas to the burners. The gas flows to the pilot burner 41 by conduit 45 and can be manually ignited. When solenoid 44 is energized, plunger 45 of valve 42 is raised to unblock passage 46 in the valve to permit gas to flow into nozzle 47 of each burner, through metering orifice 48 in the tip of the nozzle, the nozzle 47 extending Within the central opening of the Venturi tube 49 to dispose the tip within the tube. Each burner is of conventional form and includes a mixer or Venturi tube portion 49 having its end provided with openings for the entrance of air into the tube for mixture with the gas and issuance of the gas-air mixture through the ports in the burners for ignition by a flame from the pilot burner 41 disposed adjacent the ports in both gas burners.

Various known safety controls are also provided and will be briefly described. A high temperature limit control comprises a thermostat 50 (FIG. 2) located at the top rear of the burner housing 35 and which functions to open a normally closed switch S1 (FIG. 5) to deenergize the solenoid 44 of the gas supply valve 42 to prevent gas flow to the burners in the event there is no air flow over the burners or a restriction of the air flow. An air fiow device 51 (FIG. 2) is a control operating to open a switch S2 (FIG. 5) to deenergize the gas supply solenoid should there be a reduction in the amount of air being drawn over the burner and through the dryer. This device (FIG. 2) is mounted on the side wall 37 of the housing 35 at the entrance of the air duct opening therein and comprises an air flow vane 52 pivoted at 53 to protrude over the top edge of the duct so that it is in the air flow stream. The vane is connected to a mercury switch S2 controlling energization of the gas supply solenoid. When the blower is operating and air is pulled through the duct, the pressure of the air moves the vane to approximately 45 and moves the switch to its closed position. An exhaust thermostat 54 is located at the rear of the dryer and is mounted to the back wall of the cabinet in the path of the air flow. Its function is to deenergize the gas burner solenoid 44 by opening a switch S3 (FIG. 5) to interrupt a circuit of the solenoid in the event a restriction of air flow occurs in the exhaust system. The thermostat is set to open switch S2 at 180 F. and to close the switch at F. These safety controls will now be described with reference to the wiring diagram of FIG. 5.

Referring to FIG. 5, the dryer may be of the coin-controlled type and, for this purpose, is provided with a coinoperated switch S4. When the damp clothes are in the dryer, the door is closed, and a coin is inserted in the coinactuated timer control, switch S4 is closed. A circuit is provided to the motor TM of a conventional timer effective to rotate a cam to maintain switch S4 closed for a predetermined period of time of dryer operation. This circuit comprises lead L1 from one side of a 115-volt line, switch S4, conductor Cl, winding of motor TM and lead L2 to the other side of the 115-volt line.

Upon closing of switch S4 and a door switch S5, a circuit is established for energizing the drive motor 26. This circuit includes power lead L1; closed switches S4, S5; conductor C2; windings of motor 26; and power lead L2. Energization of motor 26 causes operation of the blower 25 and rotation of drum 21.

The present invention is directed to an improved control arrangement for a burner assembly, preferably but not necessarily using manufactured gas, and providing for a sufficient delay between the time the air flow movement begins and the burner is ignited to purge the burner assembly of unburned gas and allow safe ignition. More particularly, it is contemplated that this control arrangement is effective during operation of the dryer and in the event there is any interruption of power to the drum and blower drive motor, and then immediate resumption of power, such, for example, as opening of the door switch by the operator, caused by inserting or extracting clothes from the dryer, and subsequent closing of the switch by closing the door; opening and closing of the air flow control switch; or opening and closing of the thermostatic switches by cycling of these switches.

In accordance with the invention, the control arrangement includes a circuit arrangement providing for energizing the winding of the solenoid 44 of the gas valve 42 to raise the plunger 46 and allow gas to flow to the burners 43, 43 for ignition of the gas-air mixture, flowing from the burners, by the pilot burner, the circuit arrangement including electrically-controlled means for insuring operation of the drive motor 26 and thereby the blower 25 for a predetermined time period to purge the burner assembly of gas prior to energization of the solenoid 44 for flow of gas-air mixture to the burner ports for ignition by the pilot burner flame.

For this purpose, and referring to FIG. 5, the circuit for drive motor 26 having been established as. previously described, a circuit for energizing the winding of solenoid 44 is controlled by a delay timer motor DTM having a winding energizable by a circuit including the lead L1; closed switches S1, S2, S3, S4, and S5; conductors C3, C4; closed stationary contact a and movable contact b of a switch HRS; conductors C5 and C6; winding of motor DTM to the lead L2. Upon energization of motor DTM, the motor rotates its cam and its tooth moves from its engagement with a movable spring arm of a normally closed switch CS1 to permit the arm to engage its contact a with contact b of this switch, rotation of the cam being continued for a predetermined time period until its cam tooth engages movable spring arm of normally open switch CS2 to move and engage its contact a thereof with con-,

tact b of this switch.

Upon closing switch CS2, a circuit is then established for energizing the winding of solenoid 44 of gas valve 42, this circuit including lead L1; closed switches S4, S5, S1, S3, and S2; C3; closed contacts a and b of switch CS2; conductor C7; winding 44; to lead L2. Simultaneously with the energization of widing 44, a circuit is established to energize a hold relay coil HRC, this circuit including conductors C7 and C8; coil HRC; and lead L2. Upon the coil HRC being energized, the relay coil causes its contact arm b to disengage contact a and engage contact c of a switch HRS. Opening of contacts a and c of- SWitClh HRS causes the described circuit of motor DTM to be interrupted, but the closing of contacts b and c of switches HRS immediately re-establishes a circuit to the motor DTM through the normally closed contacts of switch CS1 which motor continues to rotate its cam until the cam tooth engages movable arm contact a of switch CS1 and opens normally closed contacts a and b of this switch to interrupt the circuit.

Upon the instantaneous pulse of switch CS2 by closing of its contacts by the rotating cam, the solenoid 44 and coil HRC are simultaneously energized and remain energized even when contacts a and b of switch CS2 are opened by continued rotation of the cam because contacts b and c of switch HRS are held closed by coil HRC to provide a circuit continuing the energizing of the solenoid and coil. Such circuit may be traced from lead L1; switches S4, S5, S1, S2, and S3; C3; C4; closed contacts b and c of switch HRS; conductor C8 and, in parallel, solenoid Winding 44 and relay coil HRC, to lead L2.

In the event there is an interruption of power to the drive motor 26, during operation of the dryer, by opening of any of the safety control switches S1, S2, S3, S4, and S5, the circuit to the drive motor will be broken. In addition, as all of these switches are in series in each of the circuits for the solenoid 44 and coil HRC, as well as the delay timer motor DTM, their energizing circuits will be instaneously interrupted by opening of any of these switches. However, upon the closing of the opened safety control switch or switches, the circuit to the drive motor is immediately established and the drive motor became operative to rotate the drum and blower fan, and a previously described circuit is also concurrently established to energize motor DTM which will rotate its cam, for a predetermined timeinterval prior to momentarily establishing the circuits to energize coil HRC and to energize solenoid 44 to open valve 42 for flow of gas to the burners, energization of coil HRC thereafter providing the described circuits for holding the coil HRC and solenoid 44 energized.

It will be readily apparent the improved control arrangement provides for a definite time delay in the event of interruption and immediate restoration of power during operation of the dryer, to insure any unburned gasair mixture, remaining in the burners, being purged from the burners by the air flow through the dryer prior to the admission of gas into the burners from the gas supply line. Accordingly, there is no possibility of the gas-air mixture, remaining in the burners, becoming ignited be fore reaching the burner ports and flashing back into the burner Venturis when the gas supply is interrupted and immediately restored. It has been determined an approximate ten-second delay between the time the air flow begins and the burners are iginited allows suflicient time to purge the burners of unburned gas and allows safe ignition. The present time delay control system provides a suflicient and positive delay period and is effective to instantaneously close the gas supply valve upon any interruption of power. It may be noted the system utilizes the position of two switches to provide the delay and uses an electrical holding relay to directly control the switches to provide instantaneous interruption of gas supply and subsequent resumption of the gas supply.

What is claimed is:

1. In a gas heated dryer, a rotatable drum adapted to contain articles to be dried; means for circulating air through said drum including a blower; electric motor means for rotating said drum and operating said blower; a gas burner for heating the circulated air; a normally closed valve controlling the supply of gas to said burner; a solenoid energizable to open said valve; and control circuits for said motor means and said solenoid and including a safety switch having thermostatic means normally closing said switch and responsive to a predetermined temperature of the heated air circulating through said drum to open said switch, switch means in said solenoid circuit and in series circuit relation with said safety switch and controlling energization of said solenoid, and electrically-controlled means for delaying operation of said switch means to energize said solenoid for a predetermined time interval subsequent to operation of said thermostatic means to close said safety switch.

2. In a gas heated dryer, a rotatable drum adapted to contain articles to be dried; means for circulating air through said drum including a blower; electric motor means for rotating said drum and operating said blower; a gas burner for heating the circulating air; a normally closed valve controlling the supply of gas to said burner; a solenoid energizable to open said valve; and control circuits for said motor means andsaid solenoid and including a safety switch having thermostatic means normally closing said switch and responsive to a predetermined temperature of the heated air circulating through said drum to open said switch; and switch means in said solenoid circuit and in series circuit relation with said safety switch forcontrolling energization of said solenoid; and a timer operable, upon closing of said switch by said said thermostatic means, to close said switch means to energize said solenoid after a predetermined time interval.

3. In a gas heated dryer, a rotatable drum adapted to contain articles to be dried; means for circulating air through said drum including a blower; electric motor means for rotating said drum and operating said blower; a gas burner for heating the circulating air; a normally closed valve controlling the supply of gas to said burner; a solenoid energizable to open said valve; control circuits for said motor means, and said solenoid and including a safety switch having thermostatic means normally closing said switch and responsive to a predetermined temperature of the heated air circulating through said drum to open said safety switch, and normally open time delay switch means in series circuit relation with said safety switch and controlling energization of said solenoid; and means for closing said switch means after a predetermined time interval subsequent to closing of said safety switch by said thermostatic means to energize said electric motor means.

4. In a gas heated dryer, a rotatable drum adapted to contain articles to be dried; means for circulating air through said drum including a blower; electric motor means for rotating said drum and operating said blower; a gas burner for heating the circulating air; a normally closed valve controlling the supply of gas to said burner; a. solenoid energizable to open said valve; a timer having an electric motor; control circuits for said motor means, said solenoid, and said electric motor and including a safety switch having thermostatic means normally closing said switch and responsive to a predetermined temperature of the heated air circulating through said drum to open said safety switch, and normally open switch means in series with said safety switch and controlling energization of said solenoid; and electrically-controlled means, in parallel circuit relation to said solenoid, for closing said switch means and energizable by said timer after a predetermined time interval subsequent to closing of said safety switch by said thermostatic means to energize said electric motor means.

5. In a gas heated dryer, a rotatable drum adapted to contain articles to be dried; means for circulating air through said drum including a blower; electric motor means for rotating said drum and operating said blower; a gas burner for heating the circulating air; a normally closed valve controlling the supply of gas to said burner; a solenoid energizable to open said valve; a timer having a rotatable cam, and an electric motor for rotating said cam; control circuit for said motor means, said solenoid, and said electric motor and including a safety switch having thermostatic means normally closing said switch and responsive to a predetermined temperature of the heated air circulating through said drum to open said safety switch, and normally open switch means in series with said safety switch and controlling energization of said solenoid; electrically-operated means for closing said switch means; and a switch controlling energization of said electrically-operated means and closable by said cam after a predetermined time interval subsequent to closing of said safety switch by said thermostatic means.

6. In a gas heated dryer, a rotatable drum adapted to contain articles to be dried; means for circulating air through said drum including a blower; electric motor means for rotating said drum and operating said blower; a gas burner for heating the circulating air; a normally closed valve controlling the supply of gas to said burner; a solenoid energizable to open said valve; a timer having a cam, and an electric motor for rotating said cam; a first control circuit for said motor means; a second control circuit for said timer motor; alternately establishable third and fourth control circuits for said solenoid; a first switch in each of said circuits and having thermostatic means normally closing said switch and operative to open said switch in response to a predetermined temperature of the heated air circulating in said drum; a hold relay having a coil in parallel circuit relation to each of said third and fourth control circuits and energizable simultaneously with said solenoid and having a normally closed second switch in said second control circuit and a normally open third switch in said third control circuit; and a normally open fourth switch in said fourth circuit and momentarily closable by and upon rotation of said cam to provide said third circuit to energize said solenoid, and also to energize said hold relay to open said second switch to thereby interrupt said second control circuit and to close said third switch to thereby establish said four circuit.

7. In a gas heated dryer, a rotatable drum adapted to contain articles to 'be dried; means for circulating air through said drum including a blower; electric motor means for rotating said drum and operating said blower; a gas burner for heating the circulating air; a normally closed valve controlling the supply of gas to said burner; a solenoid energizable to open said valve; a timer having a cam, and an electric motor for rotating said cam; a first control circuit for said motor means; alternately establishable second and third control circuits for said timer motor; alternately establishable fourth and fifth control circuits for said solenoid; a first switch in each of said circuits and having thermostatic rneans normally closing said switch and operative to open said switch in response to a predetermined temperature of the heated air circulating in said drum; a hold relay having a coil in parallel circuit relation to each of said fourth and fifth control circuits and energizable simultaneously with said solenoid and having a normally closed second switch in said second control circuit and a normally open third switch in said third control circuit; a fourth normally open switch in said fourth circuit and momentarily closable by and upon rotation of said cam to provide said third circuit to energize said solenoid and also to energize said hold relay to open said second switch to interrupt said second control circuit and to close said third switch to establish said fourth circuit, and a normally closed fifth switch in said third circuit to maintain energization of said timer motor upon interruption of said second control circuit and operable by said cam upon continued rotation thereof to interrupt said third circuit and thereby terminate energization of said timer motor.

8. In a gas heated dryer, a rotatable drum adapted to contain articles to be dried; means for circulating air through said drum including a blower; electric motor means for rotating said drum and operating said blower; a gas burner for heating the circulating air; a normally closed valve controlling the supply of gas to said burner; a solenoid energizable to open said valve; a timer having a cam, and an electric motor for rotating said cam; a first control circuit for said motor means; a second control circuit for said timer motor; a third control circuit for said solenoid; an electromagnetically-operated normally open first switch in said third circuit; an electromagnet energizable to close said first switch; a normally open second switch closable to energize said electromagnetic; switch means in each of said circuits and having thermo- 7 3 static means for opening and closing said switch means, References Cited by the Examiner in c 1 1 e 1 e and also establishing said second circuit to energize said 2965367 12/1960 a -7 26333 timer motor to rotate said cam for a predetermined time 5 3,068,588 12/1962 Rlchterkesslng at 263*33 interval prior to closing said second switch to energize Y said electromagnet to close said first switch to energize FREDERICK MATTESON P'lmary Exammer said solenoid. JOHN J. CAMBY, Examiner. I

Claims (1)

1. IN A GAS HEATED DRYER, A ROTATBALE DRUM ADAPTED TO CONTAIN ARTICLES TO BE DRIED; MEANS FOR CIRCULATING AIR THROUGH SAID DRUM INCLUDING A BLOWER; ELECTRIC MOTOR MEANS FOR ROTATING SAID DRUM AND OPERATING SAID BLOWE; A GAS BURNER OF HEATING THE CIRCULATED AIR; A NORMALLY CLOSED VALVE CONTROLLING THE SUPPLY OF GAS TO SAID BURNER; A SOLENOID ENERGIZABLE TO OPEN SAID VALVE; AND CONTROL CIRCUITS FOR SAID MOTOR MEANS AND SAID SOLENOID AND INCLUDING A SAFETY SWITCH HAVING THERMOSTATIC MEANS NORMALLY CLOSING SAID SWITCH AND RESPONSIVE TO A PREDETERMINED TEMPERATURE OF THE HEATED AIR CIRCULATING THROUGH SAID DRUM TO OPEN SAID SWITCH, SWITCH MEANS IN SAID SOLENOID CIRCUIT AND IN SERIES CIRCUIT RELATION WITH SAID SAFETY SWITCH AND CONTROLLING ENERGIZATION OF SAID SOLENOID, AND ELECTRICALLY-CONTROLLED MEANS FOR DELAYING OPERATION OF SAID SWITCH MEANS TO ENERGIZE SAID SOLENOID FOR A PREDETERMINED TIME INTERVAL SUBSEQUENT TO OPERATION OF SAID THERMOSTATIC MEANS TO CLOSE AND SAFETY SWITCH.

Images