US3782001A

US3782001A - Clothes dryer control

Info

Publication number: US3782001A
Application number: US00279659A
Authority: US
Inventors: C Cotton
Original assignee: Maytag Corp
Current assignee: Maytag Corp
Priority date: 1969-03-03
Filing date: 1972-08-10
Publication date: 1974-01-01
Anticipated expiration: 1991-01-01

Abstract

A control system for a clothes dryer including a dryness sensing circuit comprising a resistance-capacitance circuit portion operable for initiating termination of the clothes dryer responsive to preselected dryness conditions of articles therein. The control system further includes selectable means for precharging a capacitance circuit and effecting a treatment for ''''permanent press'''' fabrics, for example, whether they be wet or dry.

Description

United States Patent Cotton 1 Jan. 1, 11974 41 CLOTHES DRYER CONTROL 3,404,465 /1968 Charamond et a1. 34/45 3,364,586 1/1968 Adam. [751 Imam" Cotton Newwm Iowa 3,333,345 8/1967 Miller 34/45 [73] Assignee: The Maytag Company, Newton,

Iowa Primary Examiner-Meyer Perlin 22 Filed; 10 1972 Assistant Examiner-Paul Devinsky Att0rneyWi11iam G. Landwier et a1. [21] Appl. No.: 279,659

Related US. Application Data Continuation-impart of Ser. No. 124,042, March 15, 1971, Pat. No. 3,710,138, which is a division of Ser. No. 803,687, March 3, 1969, Pat. No. 3,599,342.

57 ABSTRACT A control system for a clothes dryer including a dryness sensing circuit comprising a resistancecapacitance circuit portion operable for initiating termination of the clothes dryer responsive to preselected dryness conditions of articles therein. The control system further includes selectable means for precharging a capacitance circuit and effecting a treatment for permanent press fabrics, for example, whether they be wet or dry.

12 Claims, 4 Drawing Figures [52] US. Cl 34/45, 34/48, 34/53 [51] Int. Cl. F26b 19/00 [58] Field of Search 34/45, 48, 53, 43, 34/44; 307/118; 328/4; 317/D1G. 3

[56] References Cited UNITED STATES PATENTS 3,417,480 12/1968 Thunander 34/53 m2 /a3 L 1.

Ma S

PAIENTE JAN 1 I974 SHEEI 2 BF 3 PATENTEDJAN H974 SHEET 3 OF 3 m oUooo wxxxxo WOOOOX mooodv xooxo o WX XXO wUUUUo mxxxxo mxxxoo W .MYFL WRERWU WANDLP .SLA FE.

EEAIL RPDAS X CONTACT CLOSED U MOMENTARY-CLOSED WHEN I PUSH ROD FULLY DEPRESSED 0 CONTACT OPEN VCONTACT CLOSED ONLY FOLLOWING PERM. PRESS CLOTHES DRYER CONTROL CROSS REFERENCE TO RELATED APPLICATIONS This application is a continuation-in-part of copending application Ser. No. 124,042 filed Mar. 15, 1971 by Curran D. Cotton entitled Dryer Control, now U.S. Pat. No. 3,710,138 issued Jan. 9, 1973 which in turn is a division of Ser. No. 803,687 filed Mar. 3, 1969 and now U.S. Pat. No. 3,599,342 issued Aug. 17, 1971. The U.S. Pat. No. 3,710,138 and No. 3,599,342 are assigned to the assignee of the instant application.

BACKGROUND OF THE INVENTION l.'Field of the Invention This invention relates to a dryer control system and more particularly to a circuit for a mode of operation including treatment of permanent press fabrics.

. 2. Description of the Prior Art One type of dryer control frequently used for effecting automatic termination of the drying operation of a clothes drying apparatus includes a pair of electrodes for sensing the electrical conductivity of the articles being dried. The prior art patents show a number of specific controls for determining the fabric dryness by means of a sensing circuit including a resistancecapacitance circuit portion responsive to the resistance of the fabrics across the electrodes for terminating a drying operation at a preselected dryness condition. These moisture sensing systems must be operable with a wide variety of fabric types including the synthetic fabrics, or treated fabrics, sometimes referred to as having permanent press characteristics. In addition to controlling the apparatus during a drying operation, it is desirable to provide control of the apparatus during treatment of permanent press fabrics, for example, which are dry but wrinkled.

Prior art has shown intermittent operation following a drying operation to effectively prevent the setting of wrinkles in the permanent press fabrics but prior art is silent as to providing means for controlling a dryer to effect removal of wrinkles from dry permanent press fabrics.

SUMMARY OF THE INVENTION It is an object of the instant invention to provide a control circuit operable for providing an improved mode of operation designed to effect treatment of permanent press fabrics.

It is a further object of the instant invention to provide for a clothes dryer an improved dryness sensing control circuit operable for determining the treatment required on permanent press fabrics and for controlling the dryer through a drying operation or a heat-on operation for treatment of wrinkles.

It is still a further object of the instant invention to provide an improved control circuit operable for controlling a clothes drying apparatus to terminate a drying operation responsive to a predetermined condition of dryness of the fabrics and to terminate a treatment operation responsive to completion of a timed period.

These objects are achieved in a clothes drying apparatus having a dryness sensing circuit comprising a resistance-capacitance circuit portion operable for sensing moisture of the fabrics and initiating termination of operation. The resistance-capacitance circuit portion is selectively operable for precharging a capacitor to pro- DESCRIPTION OF THE DRAWINGS The drawings illustrate a preferred embodiment of the invention with similar numerals referring to similar parts throughout the several views, wherein:

FIG. 1 is a view ofa dryer partially broken away and sectioned and incorporating the control system of the instant invention;

FIG. 2 is an electrical schematic diagram of a pre' ferred circuit embodying the permanent press treatment of the instant invention;

FIG. 3 is a chart indicating the operation of various switches of the circuit of FIG. 2; and

FIG. 4 is a view of a portion of the control components of the circuit of FIG. 2 including the preselection switch, a solenoid, and an indicator chime.

DESCRIPTION OF A PREFERRED EMBODIMENT In FIG. 1 of the accompanying drawings is shown a clothes dryer apparatus having a base 10 that serves as a support for

upstanding channel members

11 and 12 which together with crosspiece 14 support the hollow blower housing casting 17. The housing 17 includes a tubular portion 21, a divider wall 20 having a rearwardly flared inner portion defining an intake into an impeller chamber, and radially directed longitudinal webs 22 that converge toward a central axis and join with a cylindrical bearing retainer member 23. A plurality of segmental passageways are therefore defined by the tubular member 21, the bearing retainer member 23, and the supporting webs 22.

Journalled within member 23 is a revoluble drum drive shaft 31 which projects from both ends of the housing 17. Fixed to the drum drive shaft 31 adjacent the rear of the dryer is a large pulley 33 which is driven by motor 34 through a motor pulley 36, main drive belt 37, a speed reduction system (not shown) driven by the main drive belt 37, and belt 40 driven in turn by the speed reduction system.

The forward end of the drum drive shaft 31 is rigidly connected to the drum spider member 46 which has radiating spokes 51 that support a rim 52.

A horizontally mounted fabric tumbling drum 60 has a rear wall 61 which is secured to rim 52 for support and rotation by shaft 31. Rear drum wall 61 is imperforate except for a central exhaust opening defined by the circular shoulder 55 that is aligned with the blower tubular member 21. The outer periphery of the rear wall 61 is flanged to form a supporting shoulder for the imperforate cylindrical sidewall 65 which carries the clothes elevating vanes or baffles 66 for tumbling clothing within the drum 60 during rotation thereof. Cylindrical sidewall 65 is also connected to the front drum wall 67.

The front wall 67 has a centrally located access opening defined by flange 68 and an annular perforate portion 69 located concentrically around the annular flange 68. This perforate portion 69 formed by several concentric rows of holes serves as the air intake to drum 60.

Cabinet 70 is fastened to the base and encloses the entire drying machine. The cabinet has an access opening defined by flange 71 and aligned with the drum access opening thereby allowing both of the

flanges

68 and 71 to receive a rearwardly extending portion of the door gasket 72. The door 73 is hinged and forms a substantially airtight seal with the gasket 72.

Fastened to the cabinet 70 is a shroud or cowling member 74. Located between the shroud 74 and the front drum wall 67 is an open coil electric heating element 75 which extends around the inside of the cowling member 74 to raise the temperature of the air passing through the perforate portion 69 into the drum 60. A gas heater may be used in place of the electrical heating element 75.

Airflow into drum 60 through the perforate area 69 and into the blower housing 17 is produced by rotation of the revoluble impeller member 76 located in the blower housing 17. The fan pulley 77 formed integrally with the impeller 76 is driven directly by the driving motor 34 through the main drive belt 37. A felt air sea]- ing member 78 encircles the front periphery of blower housing 17 and the circular shoulder 55 to prevent air from being drawn in at the junction and thus bypassing the heater 75 and drum 60.

The blower housing casting 17 supports at least one thermostat 82 which is connected in series with the heating element 75 to maintain the interior drum 60 at the proper selected drying temperature. Also connected in series with the heating element 75 is the high limit thermostat 79 which is mounted on an upper part of the shroud member 74 so as to disconnect heating element 75 from its source of power in case the temperature near the front of the drum should rise above a predetermined selected temperature during the operation of the clothes dryer, for instance, in the event of reduced airflow through the drum 60.

In order to measure the electrical conductivity or resistance of the fabrics within the drum 60, as a measure of the condition of dryness of the fabrics, electrodes or probes 80 and 81 are mounted within the drum 60. In a preferred embodiment, the electrodes are in the form ofa pair of elongated conductor members mounted on the crown of each of the baffle members 66 to provide a contacting surface engageable by the fabrics tumbling within the drum. It will be realized that different forms of electrodes, or probes, may be used, although the type disclosed herein is a preferred construction.

Electrical energy is supplied to electrode 80, for example, by lead 84 that is connected to a brush 85 that engages the stationary slip ring 86 while the drum 60 is rotating. The slip ring 86 is mounted on the electrically insulative air sealing member 78. The slip ring 86 is in turn connected to a lead 90 which runs to the control unit 92. The electrode 81 is connected by lead 83 to the rotatable drum 60 and through the drum 60, the drive shaft 31, and blower housing 17 to the chassis including the base 10. The chassis is then connected to earth ground through a conductor 87 electrically connected with the base 10, for example. Electrode 81 is thus connected to earth ground.

The automatic control unit 92 may be secured to an upper portion of the cabinet. The lead 90 enters the control unit and is connected to the control unit to be described hereinafter.

The baffles 66 are formed of an electrically nonconductive material in order to insulate the electrodes. The electrodes, however, are electrically shorted by the contact of wet fabrics during tumbling. A plurality of baffles may be mounted for contact with the fabrics within the drum and each may be provided with electrodes and 81 with the electrode pairs being connected in parallel for achieving a greater sensitivity of control.

Referring now to FIG. 2 which illustrates the control circuitry for the clothes drying apparatus, there is shown diagrammatically a manually operable preselection means 100, which is also shown in outline form in FIG. 4. The preselection means includes a plurality of switches 101 through 109 actuatable between open and closed positions, according to the chart of FIG. 3, under control of a plurality of manually actuatable push buttons 110 through 113, in this embodiment, and indicated as Regular, Permanent Press", Damp Dry", and Air Fluff", respectively. The switches 101 through 109 are shown collectively at the right side of the diagram of FIG. 2 under control of the push buttons 110 through 113 and are shown schematically in the circuit for controlling initiation and termination of the clothes drying apparatus as will be more fully shown hereinafter. Operation of the group of switch members 101 through 109 between open and closed positions is also under the control of a selectively energizable solenoid 116, shown in FIG. 4 and indicated schematically in FIG. 2, to terminate the drying cycle.

The control circuitry of FIG. 2 includes three

conductors

118, 119, and that are selectively connectable with a conventional three-wire 220 volt, alternating current supply. For the explanation of the circuitry of FIG. 2, it will be assumed that the

conductors

118 and 119 are connected with the power lines and that the other conductor 120 is connected to the neutral line.

The chart of FIG. 3 indicates the electrical posture of the preselection switches 101 through 109 upon selection of each of the selectable cycles corresponding to the push buttons 110 through 113 and upon operation of the resetting solenoid 116. It is noted, for example, that the preselection switch 101 in the heater circuit is closed for each of the Regular, Permanent Press, and Damp Dry cycles. In the explanation of the circuit of FIG. 2, it will be assumed that a Permanent Press cycle has been selected by the operator and thus selection switches 101, 102, and 108 are closed and

preselection switches

104, 105, 106, and 107 are open while preselection switches 103 and 109 are momentarily closed during the preselection and machine energization process.

The heater 75 is connected between the first and

second conductors

118 and 119 by a circuit portion in cluding the preselection switch 101, a cycling thermostat 82, a high limit thermostat 79, and a centrifugal switch 123 in the motor 34. The centrifugal switch 123 is normally open but is operable to a closed position upon energization of the motor 34.

The drive motor 34 is energized by a circuit extending from the conductor 1 18 through a door switch 124, closed preselection switch 102, a conductor 125, junction 128 and momentarily closed preselection switch 103 to junction 127 at one side of the motor 34. The other side of the motor 34 is connected to neutral conductor 120. Subsequent to initial energization of the motor 34, centrifugal switch 126 within the motor 34 will operate and a circuit for maintaining operation of the motor will be completed from the conductor 118 through the door switch 124, preselection switch 102, conductors 125,junction 128, and conductors 130, and 131 to the motor 34. The circuit also includes switch 126 within the motor.

A cool-down thermostat 133 is also provided in the circuit to the motor 34 and is operable to a closed position at a predetermined temperature within the drum 60 of, for example, 135 F. After the dryer apparatus has operated for a period of time with the heat on, the cool-down thermostat 133 will close and maintain the motor 34 energized, while switch 124 is closed and until the temperature within the drum 60 is reduced to 135 F. This cool-down thermostat 133, therefore, provides a fabric cool-down operation following a heat-on drying operation.

The fabric dryness sensing circuit is energized from the conductor 118, through the door switch 124, selector switch 102, conductor 125, junction 128, and momentary switch 103 to junction 127 and then through conductor 134 to the junction 132. An auxiliary circuit portion for effecting a heat-on fabric treatment with Permanent Press selection is connected to junction 128 through conductor 129 and will be explained hereinafter.

After the momentary switch 103 opens, a bypass circuit from junction 128 to junction 127 around switch 103 and including conductors 130 and 131, and motor switch 126 maintain a circuit to junction 132. The junction 132 connects with a resistance

network including resistors

136 and 137 and selection switches 104, 105, and 106. The circuit continues through the junction 138 to oneside of a rectifier 135. The other side of the rectifier 135 is connected to a resistor 139 which is in turn connected to a junction 141. Extending from the junction 141 is one circuit portion including a resistor 143 in series with the electrode 80. The other electrode 81 is connected to the drum 60 and through various electrically conductive portions of the apparatus, indicated as 144 in FIG. 2, and to an earth ground through the earth ground conductor 87. Also connected to the junction 141- is a resistor 140 that is in turn connected to a junction 142'.

A capacitor 145 is connected to junction 142 and thus through the circuitry as previously described to conductor 118 on one side, and to the neutral conductor 120 on the other side. The capacitor 145, being in parallel with the

electrodes

80 and 81, will become charged through the'circuit connected to junction 132 as the fabrics become dry in a manner to be explained hereinafter. I

The capacitor is also connectable, upon selection of the Permanent Press cycle of operation, through the auxiliary circuit portion connected to junction 128 through conductor 129. The circuit from conductor 129' establishes a voltage divider network for rapidly precharging the capacitor 145 to a predetermined level' through the momentarily closed switch 109. The circuit extending from conductor 129 includes in addition to switch 109, a rectifier 150, a resistor 151 and a second resistor 152. It is clear from the circuit of FIG. 2 that upon selection of a Permanent Press cycle, switch 109 momentarily closes to complete a circuit to one side of the capacitor 145 from line 118 through door switch 124, switch 102, conductor 125,junction 128, line 129,

rectifier 150, resistor 151, switch 109, and conductor 153. The other leg of the voltage divider includes resistor 152 so that through the voltage divider network the capacitor is charged to approximately 50 volts.

lf wet clothes are in the dryer when the Permanent Press is selected so that the electrodes and 81 are bridged, the capacitor 145 will be discharged through the relatively low resistance of the clothes and subsequent charging thereof will depend upon the drying of the fabrics. If, however, the clothes within the container are dry, the capacitor 145 will not be discharged but will become further charged, through the circuitry connected to junction 132, to a predetermined voltage in a generally predetermined time period. The control circuit is thus operable for providing a Permanent Press cycle that effectively includes means for determining what treatment is required and means for controlling the apparatus through the selected treatment.

Thus, during the Permanent Press cycle with wet fabrics the capacitor 145 will be charged from the discharged reference point, as the fabrics across the

electrodes

80, 81 become dry, by the dc. circuit extending through the receifier and

resistors

139 and 140. The rate of charging of the capacitor is selected to give the desired dryness condition of the fabrics and is determined, at least in part, by the amount of resistance in circuit with the capacitor 145.

The circuit portion including selector switch 107 and resistor 146 provides a closed loop path for selectively discharging the capacitor 145 at the endof each cycle through the switch 107 to insure a consistent relationship of the charge on capacitor 145 to the dryness of the fabrics across the

electrodes

80, 81. Switch 107 is closed upon actuation of the solenoid 116 at the end of each cycle.

A gaseous discharge tube, such as a neon lamp 149, is connected in series with

resistors

155 and 157 and in turn across the capacitor 145. The neon tube 149 normally has an effectively infinite resistance; however, when the charge on the capacitor 145 reaches a predetermined value, the gas is ionized and a circuit is conducted therethrough. A thyristor, in the form of silicon controlled rectifier, or SCR 159, includes a gate portion electrically connected to one side of the neon lamp 149. The gate may be directly connected as in FIG. 2 or alternately through a resistor. Upon the firing of the neon lamp, a circuit is completed to the gate of SCR 159, which in turn becomes conductive and completes a circuit between the anode 160 and cathode 161 to effect energization of the solenoid 116 for resetting at least a portion of the selector switches 101 through 109 and thereby initiating termination of the drying operation. The solenoid energizing circuit is completed from the conductor 118 through the door switch 124, selection switch 102, a conductor 163, and selector switch 108 to one side of the solenoid 116. The other side of the solenoid 116 is connected by

conductors

164 and 165 to the anode 160 of the SCR 159. The cathode 161 of the SCR 159 is connected to the neutral conductor 120. A filter capacitor 169 and resistor 170 are connected in parallel to the SCR 159.

Energization of the solenoid 1 16 resets the preselection means 100. The resetting effects opening of the selection switches 10], 102, and 108, to terminate the sensing operation for the Permanent Press cycle and to de-energize the heater 75. It will be seen from a further analysis of FIGS. 2 and 3 that even after actuation of the solenoid 116 the motor 34 will remain energized through a cool-down circuit to effect continued tumbling of the fabrics within the drum 60 for a cool-down operation under control of the cool-down thermostat 133. Upon the temperature of the air within the drum reaching a predetermined lower temperature, the thermostat 133 will open for de-energizing the motor 34 to terminate the cycle of operation.

It will also be seen that upon the firing of the neon tube 149 responsive to a predetermined charge on the capacitor 145, actuation of the solenoid 116 will effect operation of the chime 174 which is shown schematically in FIG. 2 and in outline form in FIG. 4. This onetime operation of the chime will occur at the end of each cycle of operation. Subsequent to the completion of the sensing operation and during the cool-down operation for a Permanent Press cycle of operations, however, the solenoid 116 will be periodically reenergized for effecting a repeating chime under control of a timing circuit operable during the cool-down operation as will be more fully explained hereinafter. This repeating chime during the cool-down portion of the Permanent Press cycle of operations in this embodiment signals the operator so that the fabrics may be immediately removed following the end of the tumbling to prevent the forming of wrinkles in the fabrics.

Referring to FIG. 4, the structure and interrelationship of the solenoid 116, preselection means 100, and chime 174 will now be more fully described. The preselection means 100, the solenoid 116, and the chime 174 are mounted to a panel 175 of the dryer apparatus through a bracket 176 attached to the panel 175 with a plurality of screws 179. The preselection means 100 is mounted to the bracket 176 so that the push buttons 110-113 are accessible to the operator and selectively operable for initiating a desired cycle of operations. The solenoid 116 is mounted to the bracket 176 and is linked to a switch actuating member 180 through the linkage 181. The chime 174 includes a bell member 183 engageable by a hammer 184 that is attached through a spring member 185 to the mounting bracket 176. Actuation of the solenoid 116 will move the switch actuating member 180 toward the solenoid for resetting the switches within the preselection means 110. The actuation of the solenoid 116 will also move the chime hammer 184 for effecting engagement thereof with the chime bell 183.

During the cool-down operation a timing circuit is completed to the resistance-capacitance portion of the circuit of FIG. 2 and an actuation circuit is periodically completed to the solenoid 116 through the currentlimiting resistor 189 connected in parallel with the selector switch 108. More specifically, a timing circuit is completed to the junction 127 through the door switch 124, cool-down thermostat 133, conductor 131, and switch 126. From junction 127, the circuit'is completed to junction 132 through conductor 134. It will be seen from FIG. 3 that selection switch 106 is closed during the cool-down operation of a Permanent Press cycle only, so that a circuit is completed from the junction 132 to the resistance-capacitance portion of the circuit including rectifier 135.

Thus during the cool-down operation ofa Permanent Press cycle, and with the fabrics substantially dry as sensed by the dryness sensing control, there will be a charging of the capacitor 145 in a manner as previously described except that less resistance is in series with the capacitor 145, since

resistors

136 and 137 are bypassed. The capacitor 145 will therefore charge over a relatively short predetermined time period for actuating the neon tube 149 and gating the SCR 159. The gating of the SCR 159 will complete a circuit to the solenoid 116 for energizing the solenoid at a reduced power level, however, because of the open switch 108 resulting in the completion of the circuit through the current limiting resistor 189. The circuit extends from the conductor 118 through the door switch 124, the cool-down thermostat 133, the

conductors

130, 125, and 163 and the resistor 189 to one side of the solenoid 116. The other side of the solenoid is connected to the neutral conductor through the anode-cathode path of the SCR 159. The charging of the capacitor and the firing of the SCR 159 for energizing the solenoid 116 will continue during the cool-down operation in the Permanent Press cycle for repeatedly energizing the solenoid with a frequency of energization determined by the R-C constant of the resistancecapacitance circuit portion.

As previously indicated, the solenoid 116 is periodically actuated at a lower power level during the cooldown operation under timing control of the resistancecapacitance circuit portion. Since the switches 101 through 109 are already in the reset position, the lower power output of the solenoid 116 is sufficient for overcoming the spring pressure on the chime hammer 184 and effecting actuation of the chime 174 for issuing an audible signal.

Returning, in summary, to the operation of the circuit for premanent press fabric treatment, it has been shown that each time a Permanent Press cycle is selected, a special heaton treatment of a predetermined duration is programmed into the dryer control. In a specific embodiment, if the clothes are placed in the container dry, the dryer will operate for approximately 2 minutes with heat to effectively eliminate the wrinkles from the articles contained therein. The time period is dependent, among other factors, upon the voltage of the capacitor 145 required to fire the neon tube as compared to the precharge which is applied to the capacitor 145 through the auxiliary circuit including momentarily closed switch 109. In the absence of the circuit provided by the instant invention, the capacitor would require 12-15 minutes for charging in the presence of dry fabrics. Such an extended time far exceeds that amount of time for achieving a proper heat-on treatment of dry but wrinkled permanent press fabrics.

If, however, wet fabrics are placed in the container and Permanent Press is selected, the precharge on the capacitor 145 will be rapidly discharged through the wet fabrics bridging the electrodes. The capacitor 145 is then gradually charged to the firing voltage of neon tube 149 as the fabrics across the electrodes become dry. Responsive to the charging of the capacitor 145 and the firing of the neon tube 149, the SCR 159 will become conductive for energizing the solenoid 116 and initiating termination of operation. The Permanent Press cycle concludes with the cool-down and operation of the repeating chime.

In the drawings and specification, there has been set forth a preferred embodiment of the invention and although specific terms are employed these are used in a generic and descriptive sense only and not for purposes oflimitation. Changes in form and the proportion of'parts as well as the substitution of equivalents are contemplated as circumstances may suggest or render expedient without departing from the spirit or scope of thisinvention as further defined in the following claims.

I claim:

1. In a clothes dryer having drying means for effecting a drying operation and further having a control circuit including means for connecting said drying means and said control circuit to an electrical supply, initiation means for initiating operation of said clothes dryer 7 to effect a drying of fabrics therein, termination means for effecting deenergization of said clothes dryer, and dryness sensing means for sensing the dryness condition of said fabrics including capacitance means gradually operable from a first voltage to a second voltage as said fabrics become dry and operable at said second voltage for effecting an electrical signal to initiate termination of operation of said clothes dryer, wherein the improvement comprises: circuit means effectively connected with said electrical supply and said capacitance means and selectively actuatable for operating said capacitance means to an intermediate voltage, operation of said capacitance means from said intermediate voltage to said second voltage being effected in a substantially predetermined period of time under control of said dryness sensing means during operation of said clothes dryer in the presence of relatively dry fabrics having at least a first degree of dryness and being effected in a longer period of time in the presence of relatively wet fabrics having less than said first degree of dryness, said termination means being responsive to said electrical signal at said second voltage for actuating said termination means to initiate termination of operation of said clothes dryer.

2. In a clothes dryer as defined in claim 1 wherein said dryness sensing means and said circuit means comprise a voltage divider network operable for rapidly precharging said capacitance means to said intermediate voltage effectively independently of the fabric dryness condition and wherein said capacitance means is then gradually chargeable from said intermediate voltage to said second voltage in a substantially predetermined period of time in the presence of said relatively dry fabrics.

3. In a clothes dryer as defined in claim 1 wherein said capacitance means is gradually chargeable to said second voltage as a function of the dryness condition of said fabrics and wherein said selectively operable circuit means is momentarily operable for rapidly precharging said capacitance means to said intermediate voltage independently of said fabric dryness condition.

4. In a clothes dryer as defined in claim 3 and further including preselection means for selecting one ofa plurality of selectable cycles of operation of said clothes dryer and wherein said circuit means is associated with the selection of one of said selectable cycles for effecting the partial precharging of said capacitance means upon selection of said one selectable cycle.

5. In a clothes dryer having drying means including a heater for effecting a drying operation and further having a control circuit including means for connecting said drying means and said control circuit to an electrical supply, initiation means for initiating operation of said clothes dryer to effect a drying of fabrics therein, termination means for effecting deenergization of said clothes dryer at completion of said drying operation, and dryness sensing means for sensing the dryness condition of said fabrics including capacitance means gradually chargeable to a predetermined voltage as said fabricsbecome dry and operable at said predetermined voltage for effecting an electrical signal to initiate termination of operation of said clothes dryer, wherein the improvement comprises: precharging circuit means effectively connected with said electrical supply and said capacitance means and selectively energizable for effecting a partial precharge of said capacitance means toward said predetermined voltage; and selectable means for energizing said heater and said precharging circuit means, said capacitance means being chargeable from said partial precharge to said predetermined voltage in a substantially predetermined period of time under control of said dryness sensing means during operation of said clothes dryer in the presence of relatively dry fabrics having at least a first degree of dryness and being chargeable to said predetermined voltage in a longer period of time in the presence of relatively wet fabrics having less than said first degree of dryness, said termination means being responsive to said electrical signal at said predetermined voltage for actuating said termination means to initiate termination of operation of said clothes dryer.

6. In a clothes dryer as defined in claim 5 wherein said capacitance means is charged gradually to said predetermined voltage under control of said dryness sensing means during a drying of fabrics in said clothes dryer and wherein said capacitance means is charged rapidly to said partial precharge upon actuation of said selectable means.

7. In a clothes dryer as defined in claim 6 wherein said control circuit further includes pr'sacnon means for selecting one of a plurality of cycles of operation of said clothes dryer including a cycle of operation designated for treatment of permanent press fabrics and wherein selection of said permanent press cycle of operation effects energization of said heater and said precharging circuit means whereby the fabrics in said clothes dryer are subjected to a drying operation under control of said dryness sensing means if in said relatively wet condition and are subjected to a heat treatment for a predetermined period of time if in said relatively dry condition.

8. In a clothes dryer having drying means including a heater for effecting a drying operation and further including a control circuit including means for connecting said drying means and said control circuit to an electrical supply, initiation means for initiating operation of said clothes dryer to effect a drying of fabrics therein, termination means for effecting deenergization of said clothes dryer, and dryness sensing means for sensing the dryness condition of said fabrics including electrode means for engaging said fabrics and further including capacitance means gradually chargeable from a first voltage to a predetermined second voltage as said fabrics become dry and operable at said predetermined second voltage for effecting an electrical signal to initiate termination of operation of said clothes dryer, wherein the improvement comprises: precharging circuit means effectively connected with said electrical supply, said capacitance means, and said electrode means and being selectively energizable for effecting a partial precharge of said capacitance means toward said predetermined second voltage independently of said dryness condition; and selectively actuatable means for effecting the energization of said heater and said precharging circuit means, said capacitance means being chargeable from said partial precharge to said predetermined second voltage in a substantially predetermined first period of time under control of said dryness sensing means during operation of said clothes dryer in the presence of relatively dry fabrics having at least a first degree of dryness, said electrode means being operable in the presence of relatively wet fabrics having less than said first degree of dryness for completing a circuit through said fabrics to effect a discharging of said capacitance means from said partial precharge toward said first voltage whereby said capacitance means is chargeable from said first voltage to said predetermined second voltage in a second longer period of time under control of said dryness sensing means in the presence of said relatively wet fabrics, said termination means being responsive to said electrical signal at said predetermined second voltage for actuating said termination means to initiate termination of operation of said clothes dryer.

9. ln clothes dryer as defined in claim 8 wherein said control circuit further includes preselection means for selecting one ofa plurality of cycles of operation of said clothes dryer including a cycle of operation designated for treatment of permanent press fabrics and wherein selection of said permanent press cycle of operation effects operation of said selectively actuatable means for energizing said heater and said precharging circuit means whereby the fabrics in said clothes dryer are subjected to a drying operation under control of said dryness sensing means if in a relatively wet condition and are subjected to a heat treatment for a predetermined period of time if in a relatively dry condition.

10. In a clothes dryer as in claim 9 wherein said selectively actuatable means includes a momentary switch operable to a closed position for effecting said partial precharging of said capacitance means upon selection of said permanent press cycle of operation.

11. In a clothes dryer having drying means for effecting a drying operation and further having a control circuit including means for connecting said drying means and said control circuit to an electrical supply, initiation means for initiating operation of said clothes dryer to effect a drying of fabrics therein, termination means for effecting deenergization of said clothes dryer, and dryness sensing means for sensing the dryness condition of said fabrics including electrode means for engaging said fabrics and further including capacitance means gradually operable from a first voltage to a second voltage as said fabrics become dry and operable at said second voltage for effecting an electrical signal to initiate termination of operation of said clothes dryer wherein the improvement comprises: circuit means effectively connected with said electrical supply and said capacitance means and selectively actuatable for rapidly operating said capacitance means to an intermediate voltage, said electrode means being in circuit with said selectively energizable circuit means and said capacitance means and operable in the presence of relatively wet fabrics for effecting operation of said capacitance means from said intermediate voltage toward said first voltage, said capacitance means being operable from said intermediate voltage to said second voltage in a substantially predetermined period of time under control of said dryness sensing means during operation of said clothes dryer in the presence of relatively dry fabrics, said termination means being responsive to said electrical signal at said second voltage for actuating said termination means to initiate termination of operation of said clothes dryer.

12. In a clothes dryer having drying means including a heater for effecting a drying operation and further having a control circuit including means for connecting said drying means and said control circuit to an electrical supply, preselection means for selecting one of a plurality of cycles of operation including a cycle designated for treatment of permanent press fabrics, initiation means responsive to said preselection means for initiating operation of said clothes dryer to effect the selected cycle of operation, termination means for effecting deenergization of said clothes dryer at completion of the selected cycle of operation, and dryness sensing means for sensing the dryness condition of said fabrics and operable for producing an electrical signal to initiate termination of operation of said clothes dryer upon said fabrics reaching a predetermined degree of dryness, wherein the improvement comprises: condition responsive means operable when said permanent press cycle of operation is selected for determining the initial dryness condition of said fabrics in said clothes dryer, said dryness sensing means including a capacitance operable from a first voltage to a second voltage to produce said signal for at least one preselected cycle, said condition responsive means being operable for charging said capacitance to an intermediate voltage upon selection of said permanent press cycle said dryness sensing means being cooperable with said condition responsive means in said permanent press cycle for producing said electrical signal after a timed heat treatment of said fabrics if relatively dry fabrics having at least said predetermined degree of dryness are initially present in said clothes dryer and for producing said electrical signal after drying said fabrics to said predetermined degree of dryness under control of said dryness sensing means if relatively wet fabrics having less than said predetermined degree of dryness are initially present in said clothes dryer, said termination means being responsive to said electrical signal for effecting deenergization of said clothes dryer.

Claims

1. In a clothes dryer having drying means for effecting a drying operation and further having a control circuit including means for connecting said drying means and said control circuit to an electrical supply, initiation means for initiating operation of said clothes dryer to effect a drying of fabrics therein, termination means for effecting deenergization of said clothes dryer, and dryness sensing means for sensing the dryness condition of said fabrics including capacitance means gradually operable from a first voltage to a second voltage as said fabrics become dry and operable at said second voltage for effecting an electrical signal to initiate termination of operation of said clothes dryer, wherein the improvement comprises: circuit means effectively connected with said electrical supply and said capacitance means and selectively actuatable for operating said capacitance means to an intermediate voltage, operation of said capacitance means from said intermediate voltage to said second voltage being effected in a substantially predetermined period of time under control of said dryness sensing means during operation of said clothes dryer in the presence of relatively dry fabrics having at least a first degree of dryness and being effected in a longer period of time in the presence of relatively wet fabrics having less than said first degree of dryness, said termination means being responsive to said electrical signal at said second voltage for actuating said termination means to initiate termination of operation of said clothes dryer.

4. In a clothes dryer as defined in claim 3 and further including preselection means for selecting one of a plurality of selectable cycles of operation of said clothes dryer and wherein said circuit means is associated with the selection of one of said selectable cycles for effecting the partial precharging of said capacitance means upon selection of said one selectable cycle.

5. In a clothes dryer having drying means including a heater for effecting a drying operation and further having a control circuit including means for connecting said drying means and said control circuit to an electrical supply, initiation means for initiating operation of said clothes dryer to effect a drying of fabrics therein, termination means for effecting deenergization of said clothes dryer at completion of said drying operation, and drYness sensing means for sensing the dryness condition of said fabrics including capacitance means gradually chargeable to a predetermined voltage as said fabrics become dry and operable at said predetermined voltage for effecting an electrical signal to initiate termination of operation of said clothes dryer, wherein the improvement comprises: precharging circuit means effectively connected with said electrical supply and said capacitance means and selectively energizable for effecting a partial precharge of said capacitance means toward said predetermined voltage; and selectable means for energizing said heater and said precharging circuit means, said capacitance means being chargeable from said partial precharge to said predetermined voltage in a substantially predetermined period of time under control of said dryness sensing means during operation of said clothes dryer in the presence of relatively dry fabrics having at least a first degree of dryness and being chargeable to said predetermined voltage in a longer period of time in the presence of relatively wet fabrics having less than said first degree of dryness, said termination means being responsive to said electrical signal at said predetermined voltage for actuating said termination means to initiate termination of operation of said clothes dryer.

7. In a clothes dryer as defined in claim 6 wherein said control circuit further includes preselection means for selecting one of a plurality of cycles of operation of said clothes dryer including a cycle of operation designated for treatment of permanent press fabrics and wherein selection of said permanent press cycle of operation effects energization of said heater and said precharging circuit means whereby the fabrics in said clothes dryer are subjected to a drying operation under control of said dryness sensing means if in said relatively wet condition and are subjected to a heat treatment for a predetermined period of time if in said relatively dry condition.

9. In clothes dryer as defined in claim 8 wherein said control circuit further includes preselection means for selecting one of a plurality of cycles of operation of said clothes dryer including a cycle of operation designated for treatment of permanent press fabrics and wherein selection of said permanent press cycle of operation effects operation of said selectively actuatable means for energizing said heater and said precharging circuit means whereby the fabrics in said clothes dryer are subjected to a drying operation under control of said dryness sensing means if in a relatively wet condition and are subjected to a heat treatment for a predetermined period of time if in a relatively dry condition.