US2965367A

US2965367A - Laundry dryer control system

Info

Publication number: US2965367A
Application number: US605171A
Authority: US
Inventors: William A Ray
Original assignee: General Controls Co
Current assignee: General Controls Co
Priority date: 1956-08-20
Filing date: 1956-08-20
Publication date: 1960-12-20
Anticipated expiration: 1977-12-20

Description

Dec. 20, 1960 w. A. RAY 2,965,367

LAUNDRY DRYER CONTROL SYSTEM Filed Aug. 20, 1956 2 Sheets-Sheet 1 4 4Z LIHIT 'srAT [7 25 BLOWER INVENTOR, W/LL/AM A. @AY

AT TUE/YE Y5.

Dec. 20, 1960 w. A. RAY

LAUNDRY DRYER CONTROL SYSTEM 2 SheetsSheet 2 Filed Aug. 20, 1956 lNVE/VT 2 MAL/AM APAY 5/ MQLJAMJ I LII? F t LAUNDRY DRYER CONTROL SYSTEM William A. Ray, North Hollywood, Calif assignor to General Controls Co., a corporation of (Ialifornia Filed Aug. 20, 1956, Ser. No. 605,171

18 Claims. (Cl. 263-43) This invention relates to laundry apparatus, and more particularly to gas-fired dryers. Such dryers are loaded with wet or damp laundered material, the clothes being subjected to the heat of the products of the fuel combustion, as by the aid of a motor-operated blower. Often the container in which the clothes are placed may be in the form of a rotatable drum, producing a tumbler action. It is also common to provide a timing arrangement, to preset the period during which the drying process is effective.

It is one of the objects of this invention to provide, in a simple manner, safeguards against hazardous conditions during attempted use of the dryer. For example, it is necessary, upon failure of the pilot flame, to ensure that the supply of fuel be interrupted, and the blower continued in operation for a short time to purge the tumbler of unconsumed gases before the main burner flame is re -established.

It is also essential, after the dryer is turned ofi manually, to continue the blower operation for a short interval thereafter.

It is another object of this invention to ensure that the supply of fuel will be interrupted upon failure of the pilot flame to ignite, within a short period after the starting operation.

It is still another object of this invention, upon pilot flame failure and consequent accumulation of gas in the tumbler, to ensure against energization of the igniter until a sufficient time delay has occurred after such pilot flame failure.

This invention possesses many other advantages, and has other objects which may be made more clearly apparent from a consideration of one embodiment of the invention. For this purpose, there is shown a form in the drawings accompanying and forming a part of the present specification. This form will now be described in detail, illustrating the general principles of the invention; but it is to be understood that this detailed description is not to be taken in a limiting sense, since the scope of this invention is best defined by the appended claims.

Referring to the drawings:

Figure 1 is a schematic diagram of a control system incorporating the invention, showing the apparatus in normal inactive position;

Fig. 2 is a fragmentary diagram of certain of the control elements shown in starting position; and

Fig. 3 is a view similar to Fig. 2, illustrating the control mechanism in the position wherein the dryer is in operation.

The control elements of the system are separated from the operating elements of the dryer, by the aid of an enclosure or wall 1 (Fig. 1). Above the enclosure 1, there is shown the apparatus constituting the dryer, such as the main burner 2, pilot burner 3, blower and tumbler motor 4, a main fuel valve 5, and a pilot valve 6. The motor 4 operates the blower 4a and the tumbler 4b.

2,965,367 Patented Dec. 20, 1950 When the dryer is in operation, the blower and tumbler motor 4 is operating to blow the products of combustion from the main burner 2 through the rotating tumbler for drying the contents of the tumbler. All this is now quite common practice.

Fuel is supplied through the main valve 5, when it is open, to the burner 2. The pilot valve 6 is adapted to supply fuel to pilot burner 3. Mains 7 and 8 serve to supply electrical energy for the various control devices, and to the load operators, such as motors, valve-operating electromagnets, etc., hereinafter set forth.

The energizing circuit for the motor 4 is controlled by a circuit controller L. Whenever the circuit controller L is closed, and a door switch 9 is closed, the tumbler motor 4 is energized. The door switch 9 is arranged to deenergize the motor 4 whenever the tumbler is being loaded and unloaded, the door being open.

The circuit for the motor 4 can therefore be traced as follows: from main 8, circuit controller L, connections it) and 11, motor 4, door switch 9, to the main 7.

The main valve 5, as well as the pilot valve s, are arranged to be opend by energizing electromagnets l2 and 13. The control circuit for the pilot valve 6 is interlocked with the control of the circuit for the main valve 5 so that the pilot valve 6 must be in open position, and the pilot flame 14 in existence, before the main valve 5 may be opened.

The control circuit for the pilot valve electromagnet 13 may be traced as follows: from main 8, circuit controller L, connection 15, a second circuit controller M, connection 16, electromagnet 13, a limit switch 17, to main 7. The limit switch 17 is responsive to high temperatures to ensure shutting off the pilot. valve 6, as well as the main burner valve 5 when excessive temperatures are encountered in the dryer tumbler. This control circuit is rendered ineffective, due to circuit controller L, when the motor 4 is deenergized.

The manner in which circuit controllers L and M are opened and closed will be described hereinafter.

Let us assume that the circuit controllers L and M are closed (see Fig. 3). Closing of controller L immediately causes the motor 4 to operate. These circuit controllers also complete the circuit for the pilot valve electromagnet 13 as hereinbefore traced. As will be explained hereinafter, the circuit controller M is prevented from closing for a period after the motor 4 is energized. In this way, it is assured that there will be a purge period at the beginning of a drying cycle.

An igniter 18 for the pilot burner 3 is energized whenever the electromagnet 13 is energized through the following circuit: main 8, circuit controller L, connection 15, circuit controller M, connection 16, connection 19, normally closed circuit controller 20, the primary winding 21 of a step-down transformer 22, to the main 7. The secondary winding 23 of transformer 22 is connected to the igniter 18, and furnishes a large current to the igniter. Accordingly, when the circuit controllers L and M are in closed position, the igniter 18 is energized and the pilot burner 3 is lighted and the flame 14 is established. However, this can occur only when both circuit controllers L and M are closed, ensuring a delay after the motor 4 is energized.

The main valve electromagnet 12 has an energizing circuit through a normally open circuit controller 24 which is closed in response to the existence of a pilot flame 14, as hereinafter described. This main valve circuit is also controlled by a thermostat 25 which en sures that the main burner 2 will be extinguished when a limiting temperature is reached without otherwise closing down the system. The complete circuit for the main valve electromagnet 12 may be traced as follows: from main 8, circuit controllers L and M,

connections

16 and 3 19, circuit controller 24, connection 26, electromagnet 12, thermostat 25, door switch 9, to the main 7.

If the pilot flame I4 is not established, the circuit controller 24 remains in open position. This is accomplished by a safety system including a thermocouple 27 which, in a well-known manner, serves to energize an electromagnet coil 28 mounted on a U-shaped core 29. The U-shaped core 29 is mounted on an arm 30 fastened to a rotatable shaft 31. The arm 39 is resiliently urged in a counterclockwise direction by the aid of a spring 32, and is brought against a stop 33 as indicated in Fig. 1.

Pivoted on the shaft 31 and freely rotatable with respect thereto is an arm 34. This arm 34 carries an armature 35 adapted to cooperate with the core 29 and to be held in attracted position whenever the electromagnet coil 28 is energized. The arm 34 is reciprocated at uniform rate; for example at the rate of once per minute in a manner to be hereinafter described, so as to advance the armature 35 counterclockwise into contact with the core 29, and then to move it in a clockwise direction. If the coil 28 is energized, movement of the arm 34 in a clockwise direction during its cycle will rotate the shaft 31 in the same direction because arm 30 and core 29 will be moved together with arm 34. If, however, the coil 28 is not energized, due to the absence or failure of the pilot flame 14, then the shaft 31 is not reciprocated since the armature 35 simply moves away from the core 29. There may be subsequent reciprocations of arm 34, until such time as core 29 sticks to armature 35.

Assuming that the coil 28 is energized in response to the existence of the pilot flame 14, the circuit controller 24 is closed in response to a sufficient angular movement of the arm 34 about the axis of shaft 31. Accordingly, the main valve is opened, since the circuit previously traced is completed, and the burner is in operation.

In order to operate the circuit controller 24, an actuator arm 36 mounted on the shaft 31 is operated to cause contact between the contact points of the circuit controller 24. At the same time, in response to the energization of the electromagnet coil 28, the circuit controller 26B is opened to deenergize the igniter 18. This is accomplished by the aid of a bar or rod 37 passing diametrically through a large clearance aperture 38 in the shaft 31, and urging one of the arms of circuit controller 29 toward the right to open it. This bar or rod is moved in the same direction as shaft 31 when this shaft turns in a clockwise direction. The bar may be independently moved in a clockwise direction to open this circuit controller, because of the large clearance between the aperture 38 in the shaft 31, and the bar. The bar thus forms a detent preventing closing of switch 20 unless the bar or rod is in the vertical position of Fig. 1. The position of the detent, holding switch 20 open, is illustrated in Fig. 3.

The bar 37 is retained against withdrawal from shaft 31 by the aid of upset portions 39 on the bar.

The reciprocating movement of lever 34 is accomplished by the aid of a timer motor S, also labelled 40, which operates a timer shaft T. The circuit for the timer motor 40 is completed at the same time as motor'4 is energized, through the following circuit: from main 8, circuit controller L connection 10, motor S, connection 50, door switch 9, to the other main 7. Timer shaft T is provided with a cam 41 adapted to operate a spring arm 42 anchored at its lower end. This spring arm 42 at its upper end is connected by a link 43 to the arm 34. As the shaft T turns through one revolution, the arm 34 is likewise reciprocated through a cycle. This controller L serves to initiate operation of motor 40, as well as tumbler motor 4.

When the core 29 is picked up by the armature 35 due to energization of the coil 28, the degree of angular movement of the arm 34 is restricted. This is provided by a lock arrangement including a shaft 44. This shaft 44 is adapted to be angularly moved in a c0UJ1t wise direction when the arm 30 is moved in a clockwise direction. This is accomplished by the aid of a screw 45, mounted on the arm 30. This screw 45 has a reduced end engaging in a recess or slot 46 of a collar 47 mounted on the shaft 44. The collar 47 carries a locking pin 48 which can cooperate, as indicated in Fig. 3, with the screw 49 carried by the arm 34. Accordingly, the arm 34 can no longer move in a counterclockwise direction since pin 48 acts as an abutment against such motion. Therefore, the rotation of the cam shaft T at the rate of one revolution per minute, for example, merely oscillates the arm 34 through a limited angle as indicated by the phantom lines in Fig. 3. This is insufiicient to open the circuit controller 24.

In starting the operation of the dryer, use is made of a cam 51 mounted on a shaft I, which cam serves to operate the circuit controllers L and M in sequence. This cam has a high portion urging the circuit controller L to the open position of Fig. 1. This high portion has an opposite end which can urge the circuit controller M to closed position. In the position of Fig. 1, both circuit controllers L and M are open. A spiral spring K anchored at its outer end, is connected at its inner end to shaft J, and urges the shaft and its cam 51 continuously in a clockwise direction. It is necessary for the spiral spring K to move the cam 51 clockwise through a small angle to permit the circuit controller L to close, and to urge the circuit controller M to closed position. This occurs in sequence, the circuit controller L closing before the circuit controller M is closed. These circuit controllers operate in response to the expansion of spring K. A time delay is interposed between the two positions of the cam 51 to ensure that the blower and tumbler motor 4 may be operated for a short interval before the main burner 2 is ignited in response to the closing of the circuit controller M. This time delay is effected by the aid of a lever Q which temporarily restrains an arm I attached to shaft J.

In the inactive position, the shaft J is restrained by the aid of a stop pin P mounted on a ratchet wheel F and cooperating with the arm I. Both circuit controllers L and M are open in this position. Ratchet wheel F is freely rotatable about the shaft 1, so that the wheel F may be moved in a clockwise direction, as hereinafter described, thereby moving pin P out of restraining position, and permitting the spring K to move cam 51.

A setting pointer H is mounted on the wheel F. It is shown in Fig. 1 as cooperating with a dial 52 indicating the Off position. In this position, the pin P is active to restrian the shaft J "against the action of the spring K to maintain both circuit controllers L and M in the open position. The pointer H serves to determine the period of operation of the system. How this is accomplished will now be described.

In setting the apparatus to a selected time interval, the pointer H is moved clockwise to a starting position, such as shown in Fig. 2. Thereafter the counterclockwise or reverse movement of the wheel F occurs in a step-by-step manner, at the rate of one tooth per minute, until the pin P moves the arm I to the open circuiting position in Fig. 1. Thus the pointer H and the wheel G cooperate with motor 40 for setting the period of operation of both

motors

4 and 40. The period of operative engagement of the circuit controllers L and M are also set by this means.

This step-by-step movement is effected by an advancing pawl C. A holding pawl B is used to hold the wheel F in the position to which it has been advanced.

The advancing pawl C is mounted upon an arm R which is anchored on a shaft 53. This arm R is adapted to be reciprocated by a cam 54 mounted on the timer shaft T. Accordingly, as soon as the timer shaft T is rotated once per minute by the motor 46), the wheel F is advanced one step per minute.

When it is desired to move the pointer H manually for a setting operation in a counterclockwise direction, the pawls B and C do not hinder such movement.

In order to make it possible to adjust the pointer H by clockwise movement of the pointer to any desired position, the pawls C and B must be moved out of operative position. This is effected by the aid of a shaft A carrying a lifting cam 55. This shaft is adapted to be rotated in a clockwise direction by the aid of a conventional pushbutton mechanism 56. The lifted positions of the pawls C and B are indicated in Fig. 2, which illustrates the starting operation. After the pointer H is moved to the starting position, the pushbutton 56 is released, and pawls C and B re-eng-age wheel iF (see Fig. 3.)

In order to delay the energization of the circuit for the valves 5 and 6 and for the igniter 18 until a period of time has elapsed after initiation of operation, the shaft J is restrained against movement beyond a position in which the circuit controller L is closed. This is effected by the arm I engaging the upper surface of an arm 70 of delay lever Q. The arm 70 serves as a detent for arm I. This delay lever Q is connected by a friction slipping clutch with shaft 53 upon which the arm R is moutned. In this way, the lever Q may be moved, for a purpose to be hereinafter described, independently of arm R.

Soon after the timer motor 40 is energized by the closing of the circuit controller L, the delay lever Q is moved outwardly in a clockwise direction, through the slip clutch mechanism, by the aid of the arm R, so as to free the arm I from the starting position of Fig. 2. The arm I thus assumes another position corresponding to that shown in Fig. 3, in which the circuit controller M is closed, in sequence after circuit controller L is closed. The time delay between closing of circuit controller M and the movement of the lever Q in a clockwise direction to free arm I is provided by the slow rotation of shaft T. This time delay may be as much as one-half minute. After arm I is thus freed, the spring K urges the cam 51 to the position of Fig. 3, and both circuit controllers L and M are closed. Thus, after circuit controller I. is closed, energizing the timer motor 40, there is a delay corresponding to the operation of cam 54 to move the delay lever Q out of contact with arm I. The contacting position is shown in Fig. 2. This occurs before the circuit controller M is permitted to close.

The delay lever Q is provided with a stationary stop pin BB operating on the horizontal arm of the lever Q to prevent the lever from moving too far in a counterclockwise direction.

After the lever Q is moved clockwise out of the way, the pointer H and ratchet wheel F are moved, as hereinbefore described, in a counterclockwise direction by pawl C.

When the wheel F is sufficiently advanced in this mannet to a position corresponding to zero minutes on the dial 52, the pin or actuator P picks up the arm I and causes opening of the circuit controller M. For a period corresponding to the angular distance between zero minutes and the Off position, the blower motor 4 and the timer motor 40 continue their operation, due to continued closing of circuit controller L. This continues until the Off position of Fig. 1 is reached. In this position the cam 51 reaches its extreme counterclockwise position, opening circuit controller L. The pin P thus operates as an actuator for moving the circuit controllers L and M to initial position. The delay corresponding to the distance between zero and Off positions causes purging of the dryer of the gases; and at the conclusion of the purging operation, the dryer is returned to the inactive position of Fig. 1. Since the opening of circuit controller L occurs upon completion of a forward movement of arm R, the stopped position of shaft T is always that shown in Fig. 1.

Arm I moves past the lower surface of arm 70 of lever Q when the Off position is approached. This occurs after pin P picks up the arm I from the position of arm I of Fig. 3. Since the lower surface of arm 70 is inclined, the delay lever Q is moved by arm I out of the path of the arm I. This is permitted by the slip clutch 53.

It is desirable to permit manual turnoff of the dryer even before the preset time for drying is consumed. This is accomplished by manually moving pointer H in a counterclockwise direction to the Off position, as shown in Fig. 1. Then should the pointer H be moved again to a starting position, it is essential to ensure that the motor 4 be operated for a short time before circuit controller M closes.

In order to introduce this delay, a cam AA is mounted on the wheel F. This cam just before the Off position is reached, rotates the delay arm Q in a counterclockwise direction by coacting with the raised portion 57 of the horizontal arm of delay lever Q. The arm I has by that time passed beyond the vertical arm '73 of delay lever Q. This operation moves the lever Q in position for interposing a stop against clockwise movement of arm I. This is necessary since when pointer H is manually moved to Off position, shaft T may stop at any position, even one in which lever Q is in the releasing position of Fig. 3. Accordingly, irrespective of the angular position of the time shaft T, the delay lever Q is positively placed in operative position by cam AA, so that there is a subsequent delay in the closing of the circuit controller M by temporarily restraining arm I. Of course, :as soon as circuit controller L is closed, when a new drying period is begun, the shaft T is rotated, and the delay lever Q will be moved out of the way when cam 54 moves arm R in a clockwise direction. This delay corresponds to an interval of between fifteen seconds to one minute and fifteen seconds, depending upon the angular position of the shaft T when the dryer is manually turned 013.. In other words, a minimum of fifteen seconds for this operation is represented by the position of the shaft T in Fig. l, for then it will take only fifteen seconds to move the arm R to the right. If the shaft T should be in a position where the cam 54 is stopped in a position from that shown in Fig. 1, it will take one minute and fifteen seconds for the arm R to move the lever Q out of restraining position.

Provisions are made to ensure a delay in the deenergization of the blower and tumbler motor 4 after a pilot frame and main burner failure to ensure purging before the main burner 2 can be lighted. Thus, assume that the pilot flame 14 is extinguished: the spring 32 after a short interval will puil the core 2% to the position of Fig. 1, extinguishing the main burner 2, and the cam 41 will then reciprocate the arm 42 through a full stroke. This arm 42 operates a mechanism for rotating the shaft I in a counterclockwise direction independently of wheel F, to bring the circuit controllers L and M to an open position after a delay interval, to open circuit controllers L and M to return them to the initial position of Fig. 1. After this delay, the i niter switch 20 is permitted to close to energize igniter 21.

For this purpose, use is made of another ratchet wheel G free to rotate upon the axis of shaft J. This ratchet wheel G is normally urged by spring CC in a clockwise direction. In normal operation, the spring is prevented from moving the ratchet wheel G against the advancing pawl E and the pawl D. Advancing pawl E is mounted upon the oscillating arm 42. The timer motor S is effective, upon pilot flame failure, to rotate the shaft J, and the advancing pawl E moves the ratchet wheel G stepbystep in a counterclockwise direction until the pin DD carried by the Wheel G moves the arm EE for moving cam 51 to a position where the circuit controllers L and M are opened in succession, shutting down the system. This delay may be about five minutes. If, before this happens, the pilot flame should be re-established, the arm 7 42 is restrained against reciprocation suflicient to rotate ratchet wheel G.

About two minutes prior to ultimate shutdown, a cam 58 carried on shaft I returns to the position shown in Fig. 1. This cam normally urges bar 37 to the position shown in Fig. 3, ensuring against closing of the igniter circuit controller 20. When the cam 58 is moved by arm EE to the position of Fig. l, the bar 37 no longer restrains the circuit controller 2%) against closing. Accordingly, the igniter 18 may be energized, as well as the pilot valve operating electromagnet 13. Thus a purge period of about three minutes is effective to ensure that no unconsumed gases remain in the tumbler when the pilot burner is again ignited.

The setting of the apparatus to a starting position is illustrated in Fig. 2. In this position, the pushbutton mechanism 56 is depressed so as to release both sets of pawls CB and ED. While the button 56 is depressed, the pointer H and the corresponding ratchet wheels F and G are moved by hand to the starting position of Fig. 2, The motors 4 and ii are energized. The delay lever Q operates as a detent against the arm I so as to restrain clockwise movement of the shaft I until the following movement of the arm R to the right by the timing motor 40. In the position shown in Fig. 2, the timing motor circuit is completed through the circuit controller L, as well as the tumbler and blower motor 4. Until the timer motor rotates sufliciently to move the delay detent Q out of the path of arm I, the pilot valve electromagnet 13 and igniter 15 are not energized.

As soon as this setting is performed, the pushbutton 56 is released. The timer motor 49 now gradually moves the ratchet wheel F in a counterclockwise direction. An intermediate position is shown in Fig. 3. In this position, both of the circuit controllers L and M are in closed position under the influence of the spring K.

When the pointer H reaches the dotted line position of Fig. 3, the pin P has moved the arm I to a position just prior to the opening of the circuit controller M. The circuit controller L, however, remains closed until the pointer H reaches the Oil position of Fig. 1. In this position, the arm I, through shaft I, has moved the cam '1 to a full open position.

During the running position, the arm 3% is reciprocated through a small angle as indicated by the phantom lines in Fig. 3 since full reciprocation is not permitted by virtue of the locking pin 48. Accordingly, the time delay ratchet wheel G is not actuated.

As heretofore explained, in the event of pilot flame failure, the ratchet wheel G is moved in a counterclockwise direction, pin DD picking up arm EE and ultimately opening the circuit to the pilot valve electromagnet 13. A few minutes before that occurs, the igniter 18 will be conditioned to be energized by circuit controller Ztl, ensuring that all gases are purged from the tumbler before the pilot flame may be re-established.

The inventor claims:

1. In a control system for a clothes dryer heated by fluid fuel and having a main burner, an electricallyoperated main valve, a pilot burner, an electrically-operated pilot burner valve, a blower, and motor means for the blower: a pair of circuits, each including a circuit controller respectively for energizing the motor means and the pilot valve; a first ratchet wheel mechanism movable to a starting position to predetermine the period of energization of said circuits, and movable to a starting position; means responsive to the existence of a pilot flame to energize the main valve; means operated in response to the movement of the first mechanism to starting position for placing the first circuit controller in active position to energize its respective circuit; means for providing a delayed actuation of the second circuit controller to active position to energize its respective circuit; means for intermittently moving the first mechanism in a direction toward stopping position and for operating the 8 second"circuit controller to deener gizing positionnear the completed movement in said direction; said movement at stopping position causing the first circuit controller to move to deenergizing position; and a second ratchet wheel mechanism operated 'in response to pilot flame failure for independently operating the second and first circuit controllers sequentially to deenergizing positions.

2. In a control system: first and second control circuits, respectively including first and second circuit controllers; an actuator movable from an initial position to a starting position; means responsive to said movement for operating the first of said circuit controllers; mechanism affected by said circuits operating to move said actuator in a reverse direction; a detent operated by said mechanism to prevent operation of the second circuit controller when the actuator is moved to a starting position; means responsive to movement of the actuator toward initial position to release said detent and to operate the second circuit controller to closed position; and means responsive to the movement of the actuator in said reverse direction to initial position for sequentially opening the second and first circuit controllers.

3. In a control system for a clothes dryer heated by fluid fuel and having a main burner, an electrically-operated main valve, a pilot burner, an electrically-operated pilot burner valve, an electrically-operated igniter for the pilot burner, a blower, and motor means for the blower: circuit control means for first energizing the motor means, and then the pilot valve and igniter, said circuit control means including a normally closed supplemental circuit controller for the igniter; means responsive to the existence of a pilot flame to energize the main valve and to open said supplemental circuit controller; a detent restraining said circuit controller against closing; and time delay means operating in response to pilot flame failure for rendering said detent ineffective.

4. In a control system for a clothes dryer heated by fluid fuel and having a main burner, an electrically-operated main valve, a pilot burner, an electrically-operated pilot burner valve, an electrically-operated igniter for the pilot burner, a blower, and motor means for the blower: circuit control means for first energizing the motor means, and then the pilot valve and igniter, said circuit control means including a normally closed supplemental circuit controller for the igniter; means responsive to the existence of a pilot flame to energize the main valve and to open said supplemental circuit controller; a detent restraining said circuit controller against closing and time delay means operating in response to pilot flame failure for rendering said detent ineffective and for subsequently deenergizing the motor means and pilot valve.

5. In a control system for a main burner, an electricallyoperated main burner valve, a pilot burner, an electricallyoperated pilot burner valve, and an electrically energized igniter for the pilot burner: 21 first circuit including a first circuit controller for the pilot burner valve and the igniter; a second circuit including a second circuit controller for the igniter; means responsive to the existence of a pilot flame for energizing the main burner valve, and for deenergizing the main burner valve upon pilot flame failure, as well as for opening the second circuit closure; and means for delaying closing of said second circuit controller upon pilot flame failure, including a detent bar, a rod through which the detent bar passes with clearance to permit the main valve to be deenergized, and timing means for moving the detent bar to releasing position.

6. In a control system for a main burner, an electricallyoperated main burner valve, a pilot burner, an electricallyoperated pilot burner valve, and an electrically energized igniter for the pilot burner: an electromagnet including an armature; means responsive to the existence of a pilot flame for energizing the electromagnet; means periodically placing the armature into attracted position with respect to the electromagnet while the electromagnet is unenergized, and thereafter angularly moving the electromagnet and the armature together to an operative position; means limiting angular movement of said electromagnet and armature, while the electromagnet is energized, from said operative position; a first circuit having a first circuit controller for the main burner valve; a second circuit having a second circuit controller for the igniter; said operative position causing the first circuit controller to be closed and the second circuit controller to be opened; and means operative upon pilot flame failure, to cause the second circuit controller to close after a time interval.

7. In a control system for a main burner, an electricallyoperated main burner valve, a pilot burner, an electricallyoperated pilot burner valve, and an electrically energized igniter for the pilot burner: an electromagnet including: an armature; means responsive to the existence of a pilot flame for energizing the electromagnet; means providing a common shaft serving as a pivotal support for the electromagnet and the armature; means for angularly moving the armature about said support, toward and from the electromagnet while the electromagnet is deenergized, and then after energization, for bringing the armature and the electromagnet to an operative position; means limiting angular movement of said shaft, While the electromagnet is energized, from said operative position; a first circuit having a first normally open circuit controller for the main burner valve; a second circuit having a second normally closed circuit controller for the igniter; means including said shaft, in operative position, operating to close the first circuit controller; a rod passing through the shaft with clearance and responsive to angular movement of the shaft for operating the second controller to open position; means restraining the rod against movement, to maintain the second circuit controller open; and time delay means for releasing said rod after the electromagnet is deenergized.

8. In a control system for a heater utilizing fluid fuel and having a space through which the products of combustion pass, a main burner, a blower for the space, a pilot burner, an electrically-operated pilot burner valve, an igniter for the pilot burner, and motor means for operating the blower: a circuit having a circuit controller for energizing or deenergizing the igniter; a shaft; a rod angularly moved by the shaft in response to establishment of a pilot flame to open the said circuit controller; and delay means for moving the rod to close the circuit controller upon pilot flame failure.

9. The combination as set forth in claim 8, in which the delay means includes a step-by-step mechanism; a motor for operating said mechanism; and means for causing the motor to be operatively coupled to the mechanism upon pilot flame failure.

10. The combination as set forth in claim 8, in which the rod projects through a clearance hole in the shaft, to permit independent movement of the rod about the axis of the shaft.

11. In a control system for a clothes dryer heated by fluid fuel and having a main burner, an electrically operated main valve, 2. tumbler, a blower, and motor means for the blower: a timer motor; a first and a second circuit controller; a movable mounting having provisions for operating the circuit controllers, and biased to one position in which both circuit controllers are closed; said mounting being retractable to open the second and first controllers respectively in spaced sequence; first circuit means dependent upon said first controller being closed for operating the timer motor and said motor means; second circuit means dependent upon the second circuit controller being closed for conditioning said electrically operated main valve for energization; movable dial means having a projection engageable with the mounting for holding the mounting in fully retracted position, said dial means being movable in one direction away 10 from engaging position; means operated by the timer motor for slowly moving the dial means in the other direction; a movable locking bar holding said mounting in an intermediate position in which said second circuit controller is open and said first circuit controller is closed; and means initiated upon operation of said timer motor for retracting said locking bar after a period of time.

12. In a control system for a clothes dryer heated by fluid fuel and having a main burner, an electrically operated main valve, a tumbler, a blower, and motor means for the blower: a timer motor; a first and a second circuit controller; a movable mounting having provisions for operating the circuit controllers, and biased to one position in which both circuit controllers are closed; said mounting being retractable to open the second and first controllers respectively in spaced sequence; first circuit means dependent upon said first controller being closed for operating the timer motor and said motor means; second circuit means dependent upon the second circuit controller being closed for conditioning said electrically operated main valve for energization; movable dial means having a projection engageable with the mounting for holding the mounting in fully retracted position, said dial means being movable in one direction away from engaging position; means operated by the timer motor for slowly moving the dial means in the other direction; a movable locking bar holding said mounting in an intermediate position in which said second circuit controller is open and said first circuit controller is closed; and means operated by said timer motor for reciprocating said locking bar between holding and releasing positions; said locking bar having reset means operated upon return movement of said mounting to fully retracted position, whereby said locking bar is operative for subsequent operations despite manual overriding of said dial means.

13. In a control system for a clothes dryer heated by fluid fuel and having a main burner, an electrically operated main valve, a pilot burner, an electrically operated pilot burner valve, a tumbler, a blower, and motor means for the blower: a timer motor; a first and a second circuit controller; a movable mounting having provisions for operating the circuit controllers, and biased to one position in which both circuit controllers are closed; said mounting being retractable to open the second and first controllers respectively in spaced sequence; first circuit means dependent upon said first controller being closed for operating the timer motor and said motor means; second circuit means dependent upon the second circuit controller being closed for conditioning said electrically operated main valve for energization and for operating said electrically operated pilot burner valve; means cooperable with said second circuit means for preventing energization of said electrically operated main valve in response to failure of a flame at said pilot burner; movable dial means having a projection engageable with the mounting for holding the mounting in fully retracted position, said dial means being movable in one direction away from engaging position; means operated by the timer motor for slowly moving the dial means in the other direction; safety means operable only during pilot burner flame failure and operated by said timer motor for moving said mounting to retracted position independently of said dial means projection; and means operated by resetting of said dial means for automatically resetting said safety means.

14. In a control system for a clothes dryer heated by fluid fuel and having a main burner, an electrically operated main valve, a pilot burner, an electrically operated pilot burner valve, a tumbler, a blower, and motor means for the blower: a timer motor; a first and a second circuit controller; a movable mounting having provisions for operating the circuit controllers, and biased to one position in which both circuit controllers are closed; said mounting being retractable to open the second and first for operating the timer motor and said motor means;

second circuit means dependent upon the second circuit controller being closed for conditioning said electrically operated main valve for energization and for operating said electrically operated pilot burner valve; means cooperable with said second circuit means for preventing energilation of said electrically operated main valve in response to failure of a flame at said pilot burner; movable dial means having a projection engageable with the mounting for holding the mounting in fully retracted position, said dial means being movable in one direction away from engaging position; means operated by the timer motor for slowly moving the dial means in the other direction; safety means operable only during pilot burner flame failure and operated by said timer motor for moving said mounting to retracted position independently of said dial means projection; means operated by resetting of said dial means for automatically resetting said safety means; a movable locking bar holding said mounting in an intermediate position in which said second circuit controller is open and said first circuit controller is closed; and means operated by said timer motor for reciprocating said locking bar between holding and releasing positions; said locking bar having reset means operated upon return movement of said mounting to fully retracted position,

whereby said locking bar is operative for subsequent operations despite msirnarevemdin of said dial means.

15. in a control system: a first ratchet wheel; a first pawl for operating the first ratchet wheel; a second ratchet wheel; a second pawl for operating the second ratchet wheel; a shaft; a cam operated by the shaft; a circuit controller operated by the cam; resilient means urging the cam in one direction; a'first actuator carried by the first wheel, which actuator upon sufiicient advance of the wheel, serves to move the shaft angularly against the force of the resilient means; a timer means connected to the first pawl for intermittently advancing the first actuator; said timer having means for advancing the second ratchet wheel to move the second actuator; and condition-responsive means for rendering the said means for advancing the second ratchet wheel ineffective.

16. Ina control system: a first ratchet wheel; a-first pawl for operating the first ratchet wheel; a second ratchet wheel; a second pawl for operating the second ratchet wheel; a shaft; a cam operated by the shaft; a circuit controller operated by the cam; resilient means urging the cam in one direction; a first actuator carried by the first wheel, which actuator upon sufficient advance of the wheel,- serves to move theshaft angularly against the force of the resilient means; a timer means connected to the first pawl for intermittently advancing the first actuator; said timer having means for advancing the second ratchet wheel to move the second actuator; and condition-responsive means for rendering the said means for advancing the second ratchet wheel ineffective; said circuit controller including a pair of switches sequentially operated by the cam; said first ratchet wheel being settable to determine the period required to cause the cam to operate.

17. The combination as set forth in claim 16, in which the setting of the first ratchet wheel causes the resilient means to move the cam to operate one of the switches; and means interposing a delay before the second switch is operated.

18. The combination as set forth in claim 16, in which the setting of the first ratchet wheel causes the resilient means to move the cam to operate one of the switches; said time-r means including a reciprocating arm; a detent for the shaft; a friction clutch between the shaft and the detent; and means operated by the setting of the first ratchet wheel to move the detent into restraining position; the reciprocation of the arm serving to move the detent out of restraining position.

References Cited in the file of this patent UNITED STATES PATENTS Re. 24,235 Geldhof et al Nov. 6, 1956 2,174,275 Raney Sept. 26, 1939 2,427,178 Aubert g Sept. 9, 1947 2,519,889 Crawford Aug. 22, 1950 2,575,289 Nycum et a1 Nov. 13, 1951 2,678,814 Geldhof et al May 18, 1954