US3783529A

US3783529A - Clothes dryer with press saver cycle including periodic signals

Info

Publication number: US3783529A
Application number: US00201763A
Authority: US
Inventors: J Miller; C Wright; M Harrold
Original assignee: Motors Liquidation Co
Current assignee: Motors Liquidation Co
Priority date: 1971-11-24
Filing date: 1971-11-24
Publication date: 1974-01-08
Anticipated expiration: 1991-01-08

Abstract

A clothes dryer including a press saver cycle to obviate fabric wrinkling is provided with an intermittent buzzer signal during the extended tumbling following normal drying. The requisite intermittent signal is developed by the dryer timer control by the addition of appropriate contacts, thus avoiding the necessity for an auxiliary timer.

Description

United States Patent 1191 Miller et a1.

[11] 3,783,529 1 1 Jan. 8, 1974 CLOTHES DRYER WITH PRESS SAVER CYCLE INCLUDING PERIODIC SIGNALS [75] Inventors: James L. Miller, Dayton; Carl J.

Wright, Bellbrook; Marshall C. Harrold, Dayton, all of Ohio [73] Assignee: General Motors Corporation,

Detroit, Mich.

221 Filed: Nov. 24, 1971 21 Appl. N6; 201,763

3,499,230 3/1970 Slugantz 34/45 3,491,458 1/1970 Elders et al..... 34/45 3,409,994 12/1968 Menknm 34/45 3,398,460 8/1968 Elders 34/45 3,391,467 7/1968 Miller et a]. 34/45 3,333,345 8/1967 Miller 34/45 2,703,347 4/1955 Constantine 200/27 B Primary Examiner-William F ODea Assistant Examiner-Paul Devinsky Attorney Wil1iam S. Pettigrew et al.

[57] ABSTRACT A clothes dryer including a press saver'cycle to obviate fabric wrinkling is provided with an intermittent buzzer signal during the extended tumbling following normal drying. The requisite intermittent signal is developed by the dryer timer control by the addition of appropriate contacts, thus avoiding the necessity for an auxiliary timer.

3 Claims, 3 Drawing Figures FLUORESCEN LAMP PAIENTED JAN 8 74 L1 50 52 26 El /w. FLUORESCENT l LAMP TIMER CYCLE CHART CONTACTS 54 CLOS HEATER CON TACTS CONT new CLOSED MOTOR 40 ENERGIZED SAVER ADVANC E B U Z Z ER DEGREES PER ADVANCE TIME CYCLE O C F CLOTHES DRYER WITH PRESS SAVER CYCLE INCLUDING PERIODIC SIGNALS This invention relates to a clothes dryer having an extended press saver cycle wherein intermittent signals are developed by contacts included in the principal dryer timer.

In the past, it has been observed that wrinkles tend to set in clothes left in a dryer for significant times after the drying cycle has terminated. However, such wrinkles are obviated by continuing the dryer operation to tumble the clothes without heat. Accordingly, an operator option has been included in some domestic clothes dryers whereby an extended dryer cycle can be selected in which the clothes are tumbled to avoid setting of wrinkles.

When an extended dryer cycle is provided, it is considered desirable to provide intermittent signals, for example a periodic buzz, during the period of extended dryer operation as a reminder to the operator that the normal drying cycleis complete and the clothes should be removed. To limit the duration of the intermittent buzzing signals, auxiliary timers have been included in the dryer controls to energize the buzzer.

In contrast with the prior art, the present invention provides an intermittent signal during a press saver cycle without adding an auxiliary timer. To develop the requisite intermittent signals, modifications are made in the timer control for the clothes dryer. Development of signals having acceptable durations is possible in the instant invention in view of the operation of the particular dryer timer included in the control. A variety of timers are commercially available including those that advancecontinuously and those characterized by periodic impulse advances. Production tolerances render both the continuous and the impulse timer unacceptable if the peridoic signal is to be developed directly by the timer. This limitation of continuous drive and impulse timers requires the addition of an auxiliary timer to control the buzzer if short duration buzzing signals are to be developed. In the instant invention, the timer is characterized by periodic advances of extendedtime duration separated by quiescent intervals. This slow step'escapement permits the generation of the requisite limited time buzzer signals in a timer suitable for conventional dryer control.

Accordingly, it is an object of the present invention to provide an extended press saver mode of operation in a clothes dryer in which periodic reminder signals are developed in response to a single timer which also controls the dryer operation.

Another object of the present invention is to use a conventional slow step escapement timer in a clothes dryer having an extended press saver mode wherein the timer develops control to generate periodic signals as a reminder that the normal drying cycle is complete and that the clothes should be removed from the dryer.

These and other objects, advantages, and features of the present invention will become more readily apparent as reference is had to the accompanying specification and drawing wherein:

FIG. 1 is a view of a domestic clothes dryer having a control panel including a provision for the operator to select an extended press saver mode of dryer operation;

FIG. 2 is an electrical schematic of the dryer of FIG.

1; and

FIG. 3 is a timing and sequence chart for the timer of the dryer of FIG. 1.

Reference shoulde now be made to the drawing and in particular to FIG. 1 wherein a domestic clothes dryer is illustrated. The clothes dryer 10 has a cabinet 12 including a door 14 for access to the'dryer drum (not illustrated) where clothes are placed for drying. A control panel 16 is provided including a plurality of knobs or buttons to afford the operator control of the dryer operation. A timer control 18 allows the operator to select the length of time desired for the drying cycle; alternatively, the operator may set the timer control to select an automatic cycle. An options selector 20, included in the control panel, permits election of an extended press saver dryer mode with or without control signals. For the purpose of the present invention, the selection of a press saver mode without reminder signals is unimportant and accordingly, the following description proceeds in terms of operation pursuant to election of the press saver mode with the reminder signals. A fabrics selector 22 provides control of dryer I heat in response to the setting selected by the operator. A lint guard indicator 24 is a telltale informing the operator when-the lint filter requires cleaning. The last control on the panel 16 is a start switch 26 which must be closed to initiate dryer operation. All of the foregoing regarding the dryer controls is known for domestic clothes dryers commercially available.

In the circuit schematic of FIG. 2, three input terminals or power lines are provided whereby house power is connected to the dryer. These terminals are labeled L L and N. Terminal N represents reference ground and L and L are each at a nominal level of 118 volts with respect to N and 236 volts with respect to each other. I

A fluorescent lamp 28 is provided to light the control panel 16 and it is energized by the voltage between L, and N when the lamp control switch 30 is closed. A ballast 32 and a fluorescent light starter 34 complete this conventional fluorescent lamp circuit.

Control functions on the control panel 16 of FIG. 1 are given like reference numerals in the schematic. The timer control is included within a block 18 enclosed by dashed lines. The fabrics selector 22 of FIG. 1 is similarly enclosed by dashed lines and labeled 22. Options selector 20 is likewise enclosed by a dashed line.

The basic operation of the timerwill be summarily set forth to facilitate the following description. The timer used is of a commerciallyavailable conventional design. A typical timer of the required design is disclosed in US. Pat. No. 2,703,347 granted on Mar. 1, 1955, to A. R. Constantine and available currently as Model 275 from Kingston Division of Scott & Fetzer Company. In operation a synchronous motor is geared down to drive an eccentric which advances a timer disk having ratchet teeth on its peripheral edge and having concentric cam tracks on one face. The eccentric is connected with a drive pawl to engage a ratchet tooth and advance the disk a predetermined amount in a step-by-step manner 'wherein the movement is at a creep rate controllable by the design of the timer for each revolution of the eccentric. Inasmuch as the eccentric engages the timer disk only a portion of each cycle of rotation of the eccentric, this timer drive is aptly characterized as a slow step escapement. In the timer, the eccentric completes one revolution each seconds. As shown in FIG. 3, the timer disk is advanced 4, 6, or 8 by the eccentric depending on the timer centric engages the ratchet 36 seconds of the 180 seconds to advance the

timer disk

4, 54 seconds to advance 6, and 67 seconds to advance 8. The remaining time in each revolution of the eccentric is quiescent, the timer disk is stationary.

The concentric radial tracks on the timer disk can be provided with depressions or protuberances to cause switching as followers on the tracks are raised or lowered controlling respective contacts. For the present description, it will be assumed that associated switch contacts are closed when protuberances are encountered, being open at other times.

FIG. 2 will be considered in conjunction with the timing chart of FIG. 3 to facilitate the following description. It should be noted that one full revolution of the timer control disk represents 180 minutes of operation by the timer drive motor. As shown in FIG. 3, the number of degrees which the control disk advances for each escapement is controllable and selected to be 4, 6, or 8. During the automatic cycle, the timer motor is not continually energized; therefore, the time of the automatic cycle will exceed the 33 minutes represented for operation of the timer motor. In both the no-heat cycle and the time cycle, the timer motor runs continuously and the time of operation of the dryer is coextensive with the time of operation of the timer motor.

During operation, a heater 36 is energized across the lines L, and L To ensure that the heater is off unless the dryer drum is rotating, a centrifugal switch 38 controlled by the dryer motor 40 is serially connected with the heater 36. An overtemperature thermostat 42 is included in the heater supply to limit the maximum temperature by opening a bi-metal when the preset temperature is exceeded. Of course, other limiting type thermal switches could be used, but a bi-metal is representative of the control required.

The heater 36 is energized only when the timer contacts 44 and 45 are closed. The intervals in which the contacts 44 and 45 are closed are shown in the timing diagram. Additionally, to obtain heat, the operator must set the fabrics selector 22 such that the fabrics

selector switch contacts

46 and 47 are closed. The fabrics selector switch includes a second movable contact 48 which can complete either of two circuits through one of the fixed contacts 49 or 51 for a bias heater 50 includes in the control thermostat 52 which monitors the drying temperature andcycles to limit this temperature. The circuit completed by the movable contact 48 differs depending on whether contact 49 or 51 is engaged as a result of the inclusion or exclusion of a resistor 54. The control thermostat 52 includes a movable contact 56 which completes either the heater supply circuit or a circuit to drive the timer motor 58. Energization of the heater supply is through a path from line L, through the contacts 44 and 45, the

contacts

46 and 47, the control thermostat 52, the thermostat 42, the heater 36, and the switch 38 to the line L,.

When the control thermostat movable contact 56 completes the circuit to the timer motor 58, the motor 58 is energized between line L, and the neutral N. The timer motor circuit 'can be completed only if the movable contact 60 of the door switch 62 engages the fixed contact 64. This situation occurs whenever the door is closed. When the door is open, the movable contact 60 engages the fixed contact 66 to turn on the lamp 68 by placing it across the voltage between line L, and N. It should be understood that the door switch 62 either completes the lamp circuit orengages the fixed contact 64 depending on whether the door is open or closed.

The above described operation whereby the timer motor 58 is energized from the control thermostat is important for automatic operation. The timer motor is driven throughout most of the automatic cycle by this action of the control thermostat 52. However, as shown in the timing chart, the movable contact 70 engages the fixed contact 72 during certain predetermined intervals during the automatic cycle. In contrast with the automatic cycle operation, the timer motor 58 is driven continuously by the circuit completed through contacts 70 and 72 during the time cycle.

An air flow switch 74 and a pilot lamp 76 monitor the accumulation of lint and provide a signal when the lint filter requires cleaning.

The normal current supply for the dryer motor 40 is through the movable contact 78 and the fixed contact 80. To start the motor, the timer is set to a position in one of the three dryer cycles: the automatic cycle, the no-heat cycle, or the time cycle where, as shown in the timing chart, the contacts 78 and 80 are closed. To start the motor 40, the start switch 26 is manually closed and maintained in the closed position until the centrifugal switch represented by movable contact 82 and fixed contacts 84 and 86 removes the start winding 88 from the circuit by'closing the contacts 82 and 86. When this occurs, current is supplied the run winding 90 through a path traced from the line L through the movable contact 78, the fixed contact 80, the conductor 92, the conductor 94, the fixed contact 86, the movable contact 82, the run winding 90, a motor overload switch 96, a conductor 98, a conductor 100, the fixed contact 64 (the dryer door must be closed for the dryer to run), and the movable contact 60 to the neutral line N.

A movable contact 102 and a fixed contact 104 comprise a press saver advance and as shown in the timing chart, bridge the ofi period for the motor 40 which normally separates the automatic cycle from the no-heat cycle. Of course, this run-through feature is effective only if the movable contact 106 and the fixed contact 108 of the options selector 20 are closed pursuant to selection by the operator of the extended press-save operation. 1

During the extended press saver cycle, the timer motor must be run through acircuit distinct from that completed by movable contact 70 and fixed contact 72 to ensure that the timer motor ceases operation at the end of the automatic cycle unless the extended press saver cycle has been selected. Thus, an additional fixed contact 110 provides a connection with the voltage supplied to the run winding 90 to thereby energize the timer motor 58 during the no-heat cycle.

A single buzzer 1 12 provides information to the operator regarding the completion of dryer operation. This buzzer is operative when the movable contact 114 engages the fixed contact 116, the movable contact 118 engages the fixed contact 120, and the dryer door is closed. As shown in the timing chart, contacts 114 and 116 are closed at the termination of each of the three cycles as well as intermittently during the no-heat cycle. The intermittent signals developed in the no-heat cycle provide a continuous reminder that the normal cycle is complete and that the clothes should be re moved from the dryer. As noted above, the press saver cycle, no-heat cycle, can be selected without the buzzer. In this situation, contacts 1 l8 and 120 would be open.

In the present invention, the operation of the dryer as described and as shown in FIGS. 2 and 3 is conventional with the exception of the development of intermittent reminders during the no-heat cycle by the single timer in control of the dryer operation. As noted above, it is the design of the timer motor used in the dryer control which permits development of the requisite intermittent reminders. The slow stepescapement organization affords sufficient time in the 8 advance periods to accommodate short buzzer signals.

With the slow step escapement timer, an 8 advance requires approximately .67 seconds of drivetime in one 180 second revolution of the drive eccentric.,With this timer a control protuberance can be placed at a reasonable radius to obtain a buzzer signal of limited duration.

A buzzer signal having a nominal time of 9 seconds ispracticable. With either a continuous drive or an impulse timer, buzzer signals developed directly by the timer would be much longer, having times unacceptable for dryer use. Accordingly, auxiliary timers are re quired with continuous drive or impulse timers whereas the present invention can provide 5-15 second buzzer signals directly by modification of the principal timer.

Although the foregoing has proceeded in terms of a specific embodiment, it should be understood that various changes and modification could be engrafted thereon within the spirit and scope of the appended claims.

We claim:

1. In a clothes dryer including a rotatable drum for receiving clothes to be dried and an electric motor for rotating said drum, a control system for said clothes dryer; said control system including circuit means for controlling an automatic drying cycle and a no-heat cycle; said circuit means for controlling said cycles being operable to provide continuous tumbling of clothes in said drum in heated air during said automatic cycle and as, a press saver mode of operation, continued continuous tumbling of clothes in said drum in unheated air during said no-heat cycle after said automatic cycle to obviate wrinkling of clothes being dried; said circuit means including an alarm operable during said press saver mode of operation; an electrical power source for said control system; said v electric motor being connected to said power source through said circuit means, said circuit means including a slow step escapement sequential timer electrically connected to said power source and having drive motor switch means closeable to supply power to said electric motor during said automatic drying cycle and during said no-heat cycle and operable to interrupt power to said electric motor in an off period normally separating said automatic cycle from said no-heat cycle,,said timer having bridging switch means closeable to bridge said drive motor switch means during said off period to provide an extended press saver cycle, and said timer having signal switch means intermittently closeable during said noheat cycle to supply power to said alarm, said circuit means including a manually operated option selector switchmeans for selecting said extended press saver cycle and said alarm, said option selector switch means having first contact means closeable in series with said bridging switch means and said electric motor when said press saver cycle is selected, said selector switch means having second contact means closeable in series with said signal switch means and said alarm, said first contact means of said option selector switch means operating when closed in conjunction with said closed bridging switch means of said timer for connecting said electric motor to said power source whereby said off period for said motor is electrically bridged so that the operation of said automatic cycle extends automatically into said no-heat cycle as said extended press saver cycle; said second contact means of said option selector switch means operating when closed in con junction with the closed signal switch means of said timer for connecting said alarm to said power source so as to generate periodic signals of limited duration during the no-heat cycle portion of said extended press saver cycle, said periodic signals developing a periodic alarm on the occasion of said periodic signals to remind the operator during said press saver cycle that the drying operation is complete and the clothes should be removed from said. drum before the continuous tumbling of clothes in unheated air is terminated.

2. A clothes dryer control system as set forth in claim 1 wherein said alarm produces an audible noise on the occasion of said periodic signals, and wherein said second contact switch means of said option selector switch is selectively openable when said first contact switch means is closed to provide said press saver cycle without said audible noise.

3. A clothes dryer control system as set forth in claim 1, wherein said slow step escapement timer is operative to generate periodic signals having durations of the order of 5 to 15 seconds during operation in said extended press saver cycle.

Claims

1. In a clothes dryer including a rotatable drum for receiving clothes to be dried and an electric motor for rotating said drum, a control system for said clothes dryer; said control system including circuit means for controlling an automatic drying cycle and a no-heat cycle; said circuit means for controlling said cycles being operable to provide continuous tumbling of clothes in said drum in heated air during said automatic cycle and as, a press saver mode of operation, continued continuous tumbling of clothes in said drum in unheated air during said no-heat cycle after said automatic cycle to obviate wrinkling of clothes being dried; said circuit means including an alarm operable during said press saver mode of operation; an electrical power source for said control system; said electric motor being connected to said power source through said circuit means, said circuit means including a slow step escapement sequential timer electrically connected to said power source and having drive motor switch means closeable to supply power to said electric motor during said automatic drying cycle and during said no-heat cycle and operable to interrupt power to said electric motor in an off period normally separating said automatic cycle from said no-heat cycle, said timer having bridging switch means closeable to bridge said drive motor switch means during said off period to provide an extended press saver cycle, and said timer having signal switch means intermittently closeable during said no-heat cycle to supply power to said alarm, said circuit means including a manually operated option selector switch means for selecting said extended press saver cycle and said alarm, said option selector switch means having first contact means closeable in series with said bridging switch means and said electric motor when said press saver cycle is selected, said selector switch means having second contact means closeable in series with said signal switch means and said alarm, said first contact means of said option selector switch means operating when closed in conjunction with said closed bridging switch means of said timer for connecting said electric motor to said power source whereby said off period for said motor is electrically bridged so that the operation of said automatic cycle extends automatically into said no-heat cycle as said extended press saver cycle; said second contact means of said option selector switch means operating when closed in conjunction with the closed signal switch means of said timer for connecting said alarm to said power source so as to generate periodic signals of limited duration during the no-heat cycle portion of said extended press saver cycle, said periodic signals developing a periodic alarm on the occasion of said periodic signals to remind the operator during said press saver cycle that the drying operation is complete and the clothes should be removed from said drum before the continuous tumbling of clothes in unheated air is terminated.

3. A clothes dryer control system as set forth in claim 1, wherein said slow step escapement timer is operative to generate periodic signals having durations of the order of 5 - to 15 seconds during operation in said extended press saver cycle.