US3491458A - Electronic control circuit for a dryer with anti-wrinkle - Google Patents

Description

3,491,458 ELECTRONIC CONTROL CIRCUIT FOR AVDRYAER WITHANTI WRINKLE Filed Sept. 25, 1967 Jan. 27, 1970 v JQELDERS" ETAI;

4 Sheets-Sheet 3 f] l l l I l IIIIIIIIIIL qmkvmwmmo Q00 INVENTORfi- 4 V/A/ J 620625 ATTORNEYS United States Patent U.S. CI. 3445 7 Claims ABSTRACT OF THE DISCLOSURE This invention is directed to a control system for a clothes dryer. An electronic control circuit is provided to sense a fixed amount of moisture retention within the clothes. For example, when the clothes are dried to 10% moisture retention, the electonic control circuit will generate a control signal to actuate a switching device. The switching device, connected to one terminal of a timer motor, causes the timer to advance to the off-position. The other terminal of the timer motor is connected to a selector switch and to an intermittently energized contact which are connected in parallel. Depending on the position of the selector switch, the timer motor advances to off either continuously or intermittently. The intermittent advancement of the timer motor functions as an antiwrinkle mode of operation in the dryer. The circuit arrangement of the control system provides semi-electronic control of the drying mode of the dryer together with an anti-wrinkle mode.

BACKGROUND OF THE INVENTION Field of the invention This invention relates generally to a control system for appliances, and more particularly to a control system for a clothes dryer wherein sensing elements are placed within the clothes receptacle of the dryer to sense the relative dryness of the clothes therein.

Description of the prior art Heretofore, control systems for dryers based on terminating the drying cycle when clothing is sensed to be dry have been notably ineffective in giving consistent results when drying small loads on the damp dry setting. This condition arises because the basis for determining when to terminate the cycle is the sensed resistance of the clothing which depends on moisture content. Since the difference in resistance between a damp dry load and a completely soaked one is slight, it is difficult to determine when the clothing is in the damp dry range, especially when the load is small and strikes the resistance sensing elements only occasionally. Furthermore, prior art condition responsive drying systems required expensive electronic components since, in order to get the load 100% dry, it was necessary to build delay into the control circuit which would continue the drying cycle after the clohting was sensed to be dry. These delay circuits involved electronic RC timer circuitry 'with large resistance values and rather strict limits on the amount of electrical leakage tolerated in the capacitor. This necessitated expensive components. Prior art control systems also typically based the cool down cycle on a thermostat in the exhaust duct of the dryer. This often led to termination of cool down before the clothing was c0m pletely cooled to room temperature. With the advent of permanent press fabrics, which must be completely cooled before the drum stops rotating to prevent wrinkles, more precise control over length of the cool down cycle is desirable.

SUMMARY OF THE INVENTION The present invention is directed to the use of an electronic control circuit which senses a fixed amount of moisture retention and generates a control signal in response thereto. Also, the present invention incorporates an electronic control circuit in conjunction with a timer motor and a switching circuit to obtain a plurality of modes of operation while utilizing a minimum number of components.

Accordingly, it is an object of the present invention to provide an electronic control system wherein a timer motor has one end thereof switchably controlled through an electronic control circuit and the other end thereof either continuously controlled or switchably controlled by an anti-wrinkle circuit.

Another object of the present invention is to provide a control system for a clothes dryer to enable the clothes dryer to handle permapress fabrics and hold them wrinkle free after termination of the drying mode of operation.

Another object of the present invention is to provide a clothes dryer with better and more consistent damp-dry performance than heretofore obtainable.

Another object of the present invention is to provide a control system for a clothes dryer in which the length of the cool down cycle is precisely controlled to insure that its duration will be adequate to allow fabrics to completely cool prior to termination of the drums rotationv Another object of the present invention is to provide a control system for a clothes dryer which will terminate operation of the anti-wrinkle operation upon opening the dryer door and will leave the machine completely deenergized upon reclosing of the door.

Another object of the present invention is to pro vide a control system for a clothes dryer in which the dryers lights remain energized throughout the antiwrinkle cycle. This gives a visual indication that the dryer is still operative during anti-wrinkle which is desirable since the dryers drum is not rotated during the majority of the anti-Wrinkle cycle.

Another object of the present invention is to provide a control system for a clothes dryer wherein anantiwrinkle cycle of operation can be selected either prior to initiating the operation of the dryer or anytime thereafter.

Still another object of the present invention is to provide a control system for a clothes dryer wherein the antiwrinkle cycle of operation can be selected subsequent to any preceding cycle of operation of the dryer.

A still further object of the present invention is to provide a control system for a clothes dryer which is economical, compact in size, and simple in construction.

BRIEF DESCRIPTION OF THE DRAWINGS FIGURE 1 is an elevational front view of the control panel of the dryer showing the disposition of control knobs thereon used to initiate various modes of operation of the dryer;

FIGURE 2 is a schematic Wiring diagram showing one form of the control system of the present invention;

FIGURE 3 is an alternate arrangement of a control system constructed in accordance with the principles of this invention;

FIGURE 4 is another alternate arrangement of a control system constructed in accordance withthe principles of this invention; and

FIGURE 5 is still another alternate arrangement of a control system constructed in accordance with the principles of this invention.

3 DESCRIPTION OF THE PREFERRED EMBODIMENTS Although the control circuit of the present invention is of utility when used with any dryer construction, a particularly useful application is made to dryers for fabrics and the like, an illustrative embodiment of which is described in U.S. application Ser. No. 425,302; filed Jan. 13, 1965, now US. Patent No. 3,409,997, and assigned by the applicants, Clifton A. Cobb and Gordon J. Krolzick, to Whirlpool Corporation, assignee of the present invention.

Throughout the description of the preferred embodiments of the present invention it will be understood that like reference numerals throughout the various views of the drawings are intended to designate similar elements or components.

Seen in FIGURE 1 is a control panel 60 which may be used to facilitate selection of the desired mode of operation of the clothes dryer. The control panel 60 includes a p-ush-to-start button '61 which is depressed to initiate operation of the dryer. A lens 68:; is mounted along the lower portion of console -60 behind which is located a fluorescent lamp. The lamp is lighted throughout the drying, cool down and anti-wrinkle operations. Also mounted on the control panel 60 is an anti-wrinkle selector knob 62 which actuates a pulser timer motor to intermittently energize the drive motor of the dryer to rotate the clothes receptacle and tumble the clothes therein after termination of the drying and cool down portions of the dryers cycle of operation. A cycle selector knob 63 is provided to select either one of the three cycles of operation. The selector knob 63 may be used to select an air only operation, a damp-dry cycle of operation or an automatic cycle of operation.

Each cycle of operation appearing on selector knob 63 is provided with an adjustable time duration to enable the operator to preset the amount of time through which the cycle will operate. For example, should the operator select the automatic cycle of operation, the selector knob 63 is rotated to the desired numerical setting, indicative of time in minutes which indicates how long the dry cycle will continue after timer operation is initiated by the condition responsive electronic control of this invention. Similarly, should the operator select the damp-dry cycle of Operation, the selector knob 63 is rotated so that the desired amount of time may be selected depending upon the actual amount of dampness desired. Duration of the damp-dry cycle is entirely timer controlled, thereby giving more consistent results than with previous electronically controlled damp-dry cycles.

For a better understanding of the cooperation of the various control knobs on the control panel 60 with that of the control system of the dryer, reference is now made to FIGURE 2. FIGURE 2 shows a control system 66 which includes an electronic control circuit 67. The electronic control circuit 67 generates a control signal in response to sensing a fixed preselected amount of moisture retention in the clothes within the clothes dryer. The control system 66 is connected to a source of alternating current through a pair of lines L and L in the conventional manner.

A lamp 68 (which is located behind lens 68a) has one end thereof connected to the line L and the other end thereof connected to the line L through a stationary contactor 69a of a door switch contactor blade 69. Contactor blade 69 is in contact with contactor 69a when the dryer door is open. A door switch 70 has the normally closed contact thereof connected to the line L and the movable contactor thereof connected to one terminal of a pulser motor 71. The other terminal of the pulser motor 71 is connected to a movable contactor 72 of an anti-wrinkle switch 73. The anti-wrinkle switch 73 is controlled by the selector knob 63 shown in FIGURE 1. The mova le contactor 72 is selectively e g s ble .4 with a stationary contact 72a, which in turn, is connected to the line L through a relay contactor 74.

Also associated with the anti-wrinkle switch 73 is a second movable contactor 76 which alternately engages the stationary contacts 76a and 76b. The stationary contact 76a is connected to stationary contact 72a, and the movable contactor 76 is connected to an input terminal EC of the electronic control circuit 67 through a line 77. When the anti-wrinkle knob 62 is in the on-position, switch 73 is as shown on the drawing. Therefore, the pulser motor 71 can remain energized through contactor 72 and relay contactor 74 if the anti-wrinkle cycle is selected.

Connected in parallel with the pulser motor 71 is a relay coil 78 which, in turn, is connected to line L through the movable contactor 72 and relay contactor 74. The relay coil 78 controls the actuation of the relay confactor 74 which provides a locking circuit for relay coil 78 and pulser motor 71 if anti-wrinkle switch 73 is in the on-position. Also connected to the pulser motor 71 and relay coil 78 is a momentary contactor 75 which is actuated by the push-to-start selector 61 on the control panel 63. Operation of the control system 66 is initiated by pressing the selector 61 thereby closing switch 75 to energize the relay coil 78.

A drive motor 80 includes a start winding 81 and a run winding 82. The start winding 81 and run winding 82 are connected in parallel through a centrifugal switch 83 which shifts position after the motor has reached a predetermined speed to engage a stationary contactor 83a. One terminal of the motor 80 is connected to the line L through the door switch while the other terminal of the motor 80 is connected to line L, through timer switch T when the motor is running at its normal operating speed. However, during the initial energization of the motor 80, it is connected to the line L through timer switch T and momentary contactor a, which is actuated by push-to-start switch 61.

When the drive motor 8!] is energized the centrifugal switch 83 disengages the start winding 81 and engages the stationary contact 83a which, in turn, is connected to a buzzer 88 through momentary contractor 75a and timer switch T The timer switch T is thus connected in parallel with buzzer 88 and when the timer switch T is closed the buzzer is shunted and maintained inoperative. However, at the end of the cool down cycle timer switch T becomes open thereby allowing buzzer 88 to be energized through motor run winding until motor speed drops down and the centrifugal switch 83 disengages stationary contact 83a. At the end of the cool down cycle of the dryer when the dryer motor is de-energized, the buzzer 88 will thus give an audible indication that the drying and cool down cycles are completed.

A heat source 91 has one terminal thereof connected to line L through the timer switch T and the other termi= nal thereof connected to L through the door switch 70 and a centrifugal switch 93 which is actuated by the drive motor 80. When the selector knob 63 is in air position, timer switch T remains open thereby preventing energization of the heat source 91. Switch 93 prevents heat source 91 from being energized unless the drive motor 80 is energized.

According to the present invention, the automatic drying cycle of the dryer is controlled by electronic control circuit 67 until the moisture retention of the clothes within the receptacle reaches a predetermined value. For example, when the rnoisure retention is 10%, the electronic control circuit 67 produces a control signal to close a reed switch 89. The reed switch 89 energizes a timer motor 90 which advances a plurality of cams to sequentially deactuate the timer switches T T T and T in a sequence to control various steps in the dryers cycle of operation.

A terminal EC of the electronic control circuit 67 is connected to the line L through the line 77 and the movable contactor 76 of the anti-wrinkle switch 73. When the movable contactor 76 is in the on-position, as shown in the drawing, the electronic control circuit is energized by relay contactor 74, and when the movable contactor 76 is in the off-position, engaging stationary contact 76b, electronic control circuit 67 is energized through timer switch T centrifugal switch 83 is engagement with stationary contact 83a, movable contactor 76 in engagement with fixed contact 76b, line 77 and terminal EC A terminal EC of electronic control circuit 76 is connected to one side of the timer motor 90- and to the timer switch T, which completes the circuit to line L The other side of the timer motor 90 is connected to line L through the centrifugal switch 83 and the timer T The reed switch 89 is actuated by an electromagnetic coil 89a which is energized by the electronic control circuit 67 in response to sensing the desired predetermined retention of moisture of the clothes within the dryer. It will be understood that electromagnetic coil 89a and reed switch 89 may be replaced by a conventional electromagnetic relay.

In order to sense the relative dryness of the clothes within the dryer, a sensor assembly 54 is provided. Sensor assembly 54 comprises two electrically isolated electrodes positioned within the treatment chamber of the clothes dryer as described in US. Patent No. 3,391,468 which is issued on July 9, 1968, and assigned by the applicant, Douglas J. Walker, to Whirlpool Corporation, assignee of the present invention. The electrodes function to monitor the moisture present in the clothing as it falls against them, thereby bridging the gap from one electrode to the other. If clothing is relatively damp, a low resistance will be sensed between the electrodes, whereas dry clothing will effect a high resistance electrical bridge.

The sensor 54 has one end thereof connected to ground potential and the other end thereof connected to a terminal EC Also associated with the electronic control circuit 67 is a terminal EC which is connected to the line L through the door switch 70.

The electronic control circuit 67 includes a diode 97 which is connected in series with a resistor 98. A filter capacitor 99 has one end thereof connected to resistor 98 and the other end thereof connected to a line 100. Also connected to resistor 98 is a resistor 101 and a resistor 102. Connected between resistors 101 and 102 is a diode 103 connected in series with a resistor 104. The junction between resistors 101 and 104 is connected to terminal EC., and therefrom to the sensor 54.

The junction of diode 103 and resistor 102 is connected to line 100 through a charging capacitor 106 and to one end of the current limiting resistor 107. The other end of current limiting resistor 107 is connected to a neon lamp 108 which, in turn, has the other end thereof connected to a resistor 109 and to the gate electrode of a silicon controlled rectifier 110.

The silicon controlled rectifier 110 is connected in series with the electromagnetic coil 89a which, in turn, is connected between a voltage divider network comprising resistors 111 and 112. Voltage divider network 111 and 112 holds the DC potential down across silicon controlled rectifier 110 so that a lower rated, inexpensive device may be utilized.

For a better understanding of the operation of the control system 66, it is necessary to evaluate the cycles initiated by setting the selector knob 63 to its respective positions. By way of example, it will be assumed that the selector knob is rotated to the automatic position for complete drying of the clothes within the dryer. The selector knob 63 is rotated in the clockwise direction .(see FIGURE 1) and the further the selector knob is rotated, between 0 and 10, the more dry the clothes will be upon termination of the dryer. This action will close timer switches T T and T After setting the knob 63 the push-tostart button 61 is depressed thereby shifting movable contactors 75 and 75a to the closed position. Closure of contactor 75a will energize drive motor 80. Energization of drive motor will cause centrifugal switch 83 to engage the stationary contact 83a and the motor will remain energized through timer contact T Depressing push-tostart button 61 also energizes relay coil 78 and pulser motor 71 through movable contactor 75. Relay coil 78 actuates relay contactor 74 thereby latching the circuit closed through movable contactor 72 when the antiwrinkle switch is on. However, when the anti-wrinkle switch is in the off-position relay coil 78 and pulser motor 71 will be de-energized when the push-to-start switch 61 is released.

As the clothes within the dryer approach a predetermined level of dryness, the voltage drop across the sensor 54 increases thereby allowing the voltage level on charging capacitor 106 to build up. When the voltage level reaches approximately 70 volts, neon lamp 108 will ionize. This action will render silicon controlled rectifier 110 conductive to energize electromagnetic coil 89a and close the reed switch 89. This will initiate operation of timer motor to cause run out of the timer selector knob 63 for the period of time preselected thereon. As timer 90 advances, timer switch T opens and de-energizes the heat source and initiates the cool down portion of the cycle of operation. The duration of time before timer contact T is opened depends, of course, on where selector knob 63 was set in the range 0 to 10. This determines how dry the clothing will be when the cycle is terminated. Timer motor 90 continues to advance for approximately 7 minutes whereupon timer contact T opens to de-energize the drive motor 80.

It will be noted that if the anti-wrinkle switch 73 is in the off-position, the control system 66 is completely deenergized and the cycle of operation of the dryer is terminated. On the other hand, if the anti-wrinkle switch is in the on-position, as shown on the drawing, relay coil 78 remains energized through timer contact T and its own relay contactor 74. This will maintain pulser motor 71 energized to periodically close a pulser contactor 86, which energizes motor 80 and pediodically causes rotation of the dryer and tumbling of the clothes therein. For example, the pulser contact 86 may be closed by pulser motor 71 for a five second period each five minutes. Also, since switch 73 is in the on-position, lamp 68 will be energized throughout the anti-wrinkle cycle via relay contactor 74 and contactor blade 69 in contact with a stationary contact 69b.

According to the present invention, timer motor 90 is also energized only when pulser contactor 86 is closed. Therefore, the accumlative run out time of the timer motor 90 is extended over a relatively long period of time; for example, two to three hours. This feature greatly simplifies the complexity of the timer motor as well as reduces the cost thereof.

It will be noted that each time the pulser contactor 86 closes to energize drive motor 80, centrifugal switch 83 engages stationary contact 83a thereby energizing the buzzer 88 when the motor is again stopped by opening of pulser contact 86 during the anti-wrinkle. portion of the cycle of operation. It is further noted that should the dryer door be opened during the anti-wrinkle cycle, door switch 70 will open and power to relay coil 78 will be terminated. Thus, upon reclosing of the dryer door, the machine will not be supplied with power and its cycle of operation is terminated since relay coil 78 cannot be re-energized without depressing push-to-start switch 61.

Seen in FIGURE 3 is an alternate arrangement of a control system which is constructed in accordance with the principles of this invention and is designated generally by reference numeral 66a. The control system 66a functions in substantially the same manner as the control system 66 shown in FIGURE 2. However, control system 66a includes a line L which is connected to the centrifugal switch 93. Therefore, lines L and L may be connected to a 240 volt potential of alternating current while lines L and L are connected across a 120 volt potential of alternating current.

According to the present invention, a major advantage of control system 66a is the circuit arrangement incorporating the anti-wrinkle switch 73a. The anti-wrinkle switch 73a includes a movable contactor 73b which is connected to the relay coil 78. A stationary contact 73c associated with anti-Wrinkle switch 73a is connected to line L through the relay contactor 74, and a stationary contact 73d is connected to one side of the timer motor 90, terminal EC of the electronic control 67a, and to the centrifugal switch 83 of the drive motor 80.

By connecting the anti-wrinkle switch 73a into the circuit as shown in FIGURE 3, the anti-wrinkle mode of operation may be selected either before the dryer is placed in operation or anytime thereafter. In this circuitry embodiment, relay coil 78 is connected to the common movable contactor 73b. Therefore, with the anti-wrinkle switch in the on-position, relay coil 78 receives power through the relay contactor 74. On the other hand, with the anti-wrinkle switch in the off-position, relay 78 is energized through timer contact T centrifugal switch 83, stationary contact 73d and movable contactor 73b. This arrangement will cause the control system 66a to be de-energized when timer contact T opens if anti-wrinkle switch 73a is in the off-position. Also, the anti-wrinkle switch 73a is of the overlap type wherein movable contactor 73b engages both contact 73c and 73d for a short period of time during transfer to insure that there will be no interruption of power to relay coil 78 when the switch is transferred from one position to the other.

Another modification of the control system 66a is that the electronic control circuit 67a is connected in parallel with the drive motor 80. This circuit arrangement deenergizes the electronic control circuit 67 during the rest period of the anti-wrinkle cycle of operation thereby substantially reducing the on time of the electronic components thereof and increasing the life of the electronic control circuit. It is noted that timer contact T is closed during the anti-wrinkle portion of the dryers cycle of operation to provide the needed path to line L for timer motor 90 so that it may advance each time pulser contact 86 is closed.

Seen in FIGURE 4 is another alternate arrangement of a control system constructed in accordance with the principles of this invention and is designated generally by reference numeral 66b. The control system 66b functions in the same manner as control systems 66 and 66a.

Control system 66b includes a single contactor pushto-start switch 175 which is paralleled by the relay contactor 74. Another modification is that the anti-wrinkle switch 73a is connected only to the relay coil 78 to control actuation thereof. Also, the buzzer 88 is connected to stationary contact 83a and is paralleled by relay contactor 74, timer switch T and timer switch T Opening of timer switch T or T will cause the buzzer 88 to be energized for a short period of time as long as centrifugal switch 83 engages stationary contact 83a. During the antiwrinkle cycle of operation, timer switch T opens thereby causing the drive motor 80 to be energized periodically through pulser switch 86. Pulser switch 86 shunts timer switch T thereby completing a parallel current path for the buzzer 88. However, each time pulser switch 86 opens to de-energize the drive motor 80, centrifugal switch 83 remains engaged with stationary contact 83a for a short period of time to energize the buzzer 88.

The control system 66b is provided with an electronic control circuit 167 which is modified to utilize the fact that timer motors, such as the timer motor 90 will not operate on half-wave pulses of alternating current. Therefore, the electronic control circuit 167 merely controls the current flow of one half the cycle applied to the timer motor 90 while continuously applying the other half of the cycle thereto.

Electronic control circuit 167 includes a pair of diodes 168 and 169 connected in series with resistors 170 and 171 respectively. Diode 168 and resistor 170 apply halfwave pulses to a charging capacitor 172 which is connected in parallel with the sensor 54. On the other hand, diode 169 and resistor 171 apply half-wave pulses of alternating current to a filter network comprising capacitor 173 and resistor 174. The filter network causes direct current to be applied at circuit point 176 which, in turn, is connected to the anode of a silicon controlled rectifier 177 through series connected resistors 178 and 179. A resistor 180 has one end thereof connected between the junction of resistor 170 and capacitor 172 and the other end thereof connected to the anode of a diode 181. The cathode of diode 181 is connected at the junction of resistors 178 and 179. Connected at the junction of resistor 180 and diode 18-1 is a neon lamp 182 which has the other end thereof connected to the gate electrode of silicon controlled rectifier 177. Also connected to the gate electrode of silicon controlled rectifier 177 is a resistor 183.

Connected in parallel with resistor 179 and silicon controlled rectifier 177 is a capacitor 184 which is used to shunt transient voltages which might otherwise render the silicon controlled rectifier 177 conductive before the desired predetermined moisture retention is sensed by the sensor 54. A diode 186 has its cathode connected to capacitor 184 and resistor 179 and its anode connected to terminal EC of the electronic control circuit 167. Also connected to terminal EC is the cathode of a diode 187 which has its anode connected to terminal EC through a line 188.

As mentioned hereinabove, the electronic control circuit 167 utilizes the advantage that timer motors operate only when full wave alternating current is applied thereto, and remain inoperative when half-wave pulses of alternating current are applied to the motor. Therefore, the timer motor 90 receives half-wave alternating current pulses through diode 187 until such time as the silicon controlled rectifier 177 is rendered conductive to pro vide a current path through the diode 186, resistor 179, and the silicon controlled rectifier 177 for the opposite polarity. Diode 181 provides a current path to discharge the voltage on charging capacitor 172 after silicon controlled rectifier 177 goes into conduction, and functions as a blocking diode during the drying cycle of operation to eliminate the possibility of charging capacitor 172 from being charged by the direct current applied at circuit point 176. By maintaining the capacitor 172 discharged after silicon controlled rectifier 177 fires, the neon lamp 182 is prevented from unnecessary ionization thereby increasing the life of the neon lamp.

In operation, the control system 661) receives power from lines L and L while the heat source 91 receives power from lines L and L Assuming that the operator turns the anti-wrinkle switch 73a to the on-position and selector knob 63 to the arbitrary number 10 of the automatic cycle of operation, the control system 66b functions as follows. Upon depr%sing the push-to-start switch 175, relay coil 78 is energized through closed timer contact T and anti-wrinkle switch 73a in the on-position. This action closes relay contactor 74 which bypasses the pushto-start switch and latches the circuit closed. Power is now applied to the electronic control circuit 167 and pulser motor 71 through timer switch T and relay contactor 74. The drive motor 80 receives power through the relay contactor 74, timer switch T and timer switch T As the drive motor 80 increases in speed, sufficient to actuate the centrifugal switch 83, the start winding 81 is de-energized and the motor continues to run through winding 82. At this time, centrifugal switch 93 is actuated to energize the heat source 91 through timer switch T and the drying cycle of operation is initiated.

When the electronic control circuit 167 senses a predetermined moisture retention within the clothes, for example, approximately 10% moisture retention, silicon controlled rectifier 177 is rendered conductive thereby applying full-wave alternating current voltage to the timer motor 90. Timer motor 90 continues to run until the timer switch T opens to de-energize the heat source 91 thereby terminating the drying portion of the cycle of operation of the dryer. At this point, the cool down operation is initiated and the drive motor 80 continues to run. After approximately seven minutes, timer motor 90 causes timer switch T to open to de-energize the drive motor 80. It will be understood that if the anti-wrinkle switch 73a was in the off-position, the entire control system 66b would be de-energized as the relay coil 78 would also be de-energized by opening timer switch T However, with the anti-wrinkle switch in the on-position, the main drive motor 80 will be de-energized while the electronic control circuit 167 and the pulser motor 71 remain energized through relay contactors 74 and timer switch T The pulser motor 71 continues to run and periodically closes pulser switch 86 for approximately five seconds during each five minute interval for a period of approximately two hours. This action intermittently energizes the timer motor 90 as well as the drive motor 80 to rotate the clothes receptacle and tumble the clothes therein. At the end of the accumulated time of timer motor 90 timer switch T opens to completely de-energize the control system 66b.

When the selector knob 63 is placed in the damp-dry position, timer contact T connected to timer motor 90, is closed throughout the cycle thereby causing timer motor 90 to control all portions of the cycle of operation of the dryer.

Seen in FIGURE 5 is an alternate arrangement of a control system constructed in accordance with the principles of this invention and is designated generally by reference numeral 66c. Control system 660 is substantially the same as control system 66b shown in FIGURE 4 with the exception of the electronic control circuit. Control system 66c includes an electronic control circuit 267 which, in turn includes a diode 268 and a resistor 269 connected in parallel therewith. The diode 268- and resistor 269 are connected in series with the timer motor 90. Connected in shunt relation with timer motor 90 is a silicon controlled rectifier 270 which has its anode connected to timer switch T Connected to the gate electrode of silicon controlled rectifier 270 is a resistor 271 and a neon lamp 272. The other end of neon lamp 272 is connected to a resistor 273 which is connected to a capacitor 274- and the sensor 54. A resistor 276 is connected in parallel with capacitor 274 to provide a discharge path for the capacitor during each cycle of the "applied alternating current voltage.

The control system 660 functions in substantially the same manner as control system 66b with the exception of the operation of electronic control circuit 267. For example, during the automatic cycle of operation of control system 660, timer contact T is closed thereby completing the circuit of silicon controlled rectifier 270. As long as the clothes within the receptacle remain wet, sensor 54 is essentially a short circuit and capacitor 274 is charged on each negative half-cycle of the AC line. Charging of capacitor 274 will cause ionization of neon lamp 272 to render silicon controlled rectifier 270 conductive thereby providing a shunt current path around timer motor 90. This action prevents timer motor 90 from running as only half-wave pulses are applied thereto through diode 268. However, as the clothes within the receptacle become more dry, sensor 54 appears as a relatively high resistance thereby decreasing the charge applied to capacitor 274 sufficient to prevent ionization of neon lamp 272. Therefore, silicon controlled rectifier 270 will no longer be rendered conductive during negative half cycles of the AC line and current will flow through timer motor 90 during both negative and positive half cycles of the applied alternating current voltage. This action advances timer motor and the sequential cams associated therewith to sequentially control the operation of timer switches T T It will be understood that during the damp-dry or air cycles of operation, timer switch T remains open to allow energization of timer motor 90 so that the timer motor can control the entire cycle of operation of the dryer.

Therefore, the control systems of the present invention provide unique and novel means for sequentially controlling the various cycles of operation of a dryer by combining electronic circuitry to control the drying portion of the cycle of operation of the dryer to a predetermined condition of moisture retention whereafter the drying operation is continued to be controlled by a timer motor. Additionally, the timer motor controls the auxiliary portions of the cycle of operation such as cool down and anti-wrinkle. By utilizing the circuit arrangement of the present invention, it will be seen that by combining the semielectronic dry control with that of the anti-wrinkle circuits, the number of components within the control systems is greatly reduced and the overall circuitry of the control systems is simplified.

Although minor modifications might be suggested by those versed in the art, it should be understood that we wish to embody within the scope of the patent warranted hereon all such modifications as may reasonably and properly come within the scope of our contribution to the art.

The embodiments of the invention in which an exclu- 1sive property or privilege is claimed are defined as folows:

1. A control system for a clothes dryer comprising:

a receptacle for receiving clothes to be dried;

a heat source for supplying heat to the interior of said receptacle;

a drive motor mechanically connected to said receptacle to cause rotational movement thereof;

centrifugal switch means actuated by rotation of said drive motor having one terminal connected to a run winding of said drive motor and a normally open terminal, selectable timer means for selecting one of a plurality of cycles including,

a. timer motor having two terminals for receiving electrical power, one of said timer motor terminals being connected to said one terminal of the centrifugal switch means;

an initially closed switch opened by predetermined operation of said timer motor connecting said normally open terminal to one side of a power source thereby connecting said drive motor and said timer motor to said one side of a power source for an initial operation of said timer;

pulser switch means having one terminal thereof electrically connected to said one terminal of said centrifugal switch means and having another terminal;

anti-wrinkle selector switch means to connect said one side of a power source to the other terminal of said pulser switch means and for rendering said pulser switch means operative to periodically close a switch between said pulser terminals when said selector switch means is in one position and for rendering said pulser means inoperative when said selector switch means is in another position; and

condition sensing switch means electrically connected to the other of said terminals of said timer motor to connect the other side of the power source to the timer motor and initiate operation of said timer motor in response to a predetermined condition of the control system,

whereby said timer motor is energized through said pulser switch means when said anti-wrinkle selector switch means is in one position at a time subsequent to the initial operation of said timer.

2. A control system for a clothes dryer comprising: receptacle means for receiving the clothes to be dried; dryness sensing means positioned within said receptacle means and engageable with the clothes being dried to sense a predetermined condition of moisture retention of the clothes; drive means mechanic-ally connected to said receptacle means to cause rotational movement thereof; selectable timer means for selecting one of a plurality of preprogrammed sequential cycles of operation; timer controlled switch means for energizing said timer means and said drive means during an initial opera tion of said timer means; sensing switch means connected to said dryness sensing means for controlling the timing out function of said timer means in response to sensing predetermined condition of moisture retention of the clothes;

pulser switch means for periodically rendering said timer means and said drive motor operative at a time subsequent to the initial operation of said timer means; and t selector switch means for disabling said pulser switch means, thereby rendering said tilner means and 'said drive meanswcontinuously inoperative in response to said timer means at said subsequent time.

3. A control system for a clothes dryer according to claim 2 wherein said sensing switch means cooperates with atsecond timer switch means associated with said timer means to render said timer means operative and said sensing switch means inoperative when one of said plurality of programmed sequential cycles of operations is selected.

4. A control system for a clothes dryer according to claim 3 wherein said sensing switch means includes a capacitor connected to said dryness sensing means whereby the voltage level on said capacitor is indicative of the relative moisture retention of the clothes within said receptacle means; a silicon controlled rectifier having its anode connected to a voltage source, said silicon controlled rectifier being connected in parallel with said timer means; a neon lamp having two terminals, one of said terminals connected to said charging capacitor and the other of said terminals connected to the gate electrode of said silicon controlled rectifier; whereby ionization of said neon lamp in response to moisture retention of the clothes will render said silicon controlled "rectifier conductive thereby maintaining said timing means inoperative until said predetermined condition of moisture retention is sensed.

5. A control system for a clothes dryer according to claim 2 wherein said sensing switch means includes a capacitor connected to said dryness sensing means whereby the voltagelevel on said capacitor is indicative of the relative dryness of the clothes within said receptacle means, a silicon controlled rectifier having its anode connected to a direct current sonrce; a neon lamp having two terminals, one of said terminals connected to said charging capacitor and the other of said terminals connected to the gate electrode of said silicon controlled rectifier; whereby, ionization of said neon lamp in response to said predetermined condition of moisture retention will render said silicon controlled rectifier conductive thereby initially rendering said timer means operativein response to said dryness sensing means sensing said predetermined condition of moisture retention. 7

V 6. A control system for a clothes dryer according to claim 2 wherein said sensing switch means includes a capacitor connected to said dryness, sensing means whereby the voltage level on said capacitor is indicative of the relativemoisture retention of the clotheswithin the receptacle means; a silicon controlled rectifier having its anode connected to a voltage source; a neon lamp having two terminals, one of said terminals connected to said charging capacitor and the other of said terminals connected to the gate electrode of said silicon controlled rectifier; whereby, ionization of said neon lamp in response to the moisture retention of the clothes will render said silicon controlled rectifier conductive thereby maintaining said timer means inoperative until said predetermined condition of moisture retention is sensed.

7. A control system for a ,clothes dryer comprising;

arreceptacle for receiving clothes to be dried; t

a heat source for supplyingtheat to the interior of said receptacle;

a drive motor mechanically connected to said receptacle to cause rotational movement thereof;

centrifugal switch means actuated by rotation of said drive motor having one terminal connected to a run winding of said drive motor,

selectable timer means for selecting one of a plurality of cycles inciuding a timer mot-or having two terminals for receiving electrical power, one of said timer motor terminals being connected to said one terminal of the centrifugal switch means;

an initially closed switch opened by predetermined operation of said timer motor connecting said one terminal to one side of a power source thereby connecting said drive motor and said timer motor to said one side of a power source for an initial operation of said timer;

pulser switch means having one terminal thereof electrically connected to said one terminal of said centrifugal switch means and having another terminal;

anti-wrinkie selector switch means connected to said one side of a power source, it

a relay connectcd to said anti-wrinde selector switch means and to the other side of said power source,

a relay switch operated by said relay connecting the other'terminal of said pulser switch means to said one side of a power source and for rendering said pulser switch means operative to periodically close a switch between said pulser terminals when said selector switch means is in one position and for rendering said pulser means inoperative when said selector switch means is in another position; and

condition sensing switch means electrically connected to said timer motorrto control operation of said timer motor during the initial operation of said timer in response to a predetermined condition of the control system, whereby said timer motor is energized through said pulser switch means when said antiwrinkle selector switch means is in one position at a time subsequent to the initial operation of said timer.

References Cited I UNITED STATES PATENTS 3,394,465 7/1968 Janke 3445 3,398,460 8/1968 Elders 34-45 3,398,461 8/1968 Ianke 34-45 3,286,359 11/1966 Orr et al. 3453 X 3,286,364 11/1966 Morrison et a1. -1 34-53 X 3,293,769 12/1966 Graham 3453 X 3,335,501 8/1967 Janke et a1. 34 53 X 3,365,809 1/1968 Eppley 34 45 X 3,381,389 5/1968 Kurowski 34-53 X JOHN J. CAMBY, Primary Examiner U.S. Cl. X.R. 34-53, 55 5

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