US3681729A

US3681729A - Dryer control circuit employing timer having two speeds

Info

Publication number: US3681729A
Application number: US42676A
Authority: US
Inventors: Alvin J Elders
Original assignee: Whirlpool Corp
Current assignee: Whirlpool Corp
Priority date: 1970-06-02
Filing date: 1970-06-02
Publication date: 1972-08-01
Anticipated expiration: 1989-08-01

Abstract

A dryer control includes two camstacks, one operating continuously with the timer motor and the other driven by the timer motor under the control of a bimetal strip, connected in series with the dryer motor to provide intermittent operation thereof in accordance with the heat generated by the motor current traversing the bimetal strip, thereby to provide two modes of operation in a dryer program having drying, cool down and anti-wrinkle cycles.

Description

United States Patent Elders 154] DRYER CONTROL CIRCUIT EMPLOYING TIMER HAVING TWO SPEEDS [72] Inventor: Alvin J. Elders, Stevensville, Mich.

[73] Assignee: Whirlpool Corporation, Benton Harbor, Mich.

[22] Filed: June 2, 1970 [21] Appl. No.: 42,676

Related US. Application Data [62] Division of Ser. No. 836,465, June 25, 1969,

Pat. No. 3,571,945.

[52] US. Cl ..337/3, 200/38 R, 219/493, 307/141, 337/301 [51] Int. Cl. ..Hlh 3/54, HOlh 7/06, l-lOb l/02 [58] Field of Search ..337/301, 302, 303, 304, 305, 337/341, 352, 353, 3;307/141, 132, 133,

[ 51 Aug. 1, 1972 5/1956 Raney ..337/302X 9/1966 Guenther eta1..........307/141 X Primary Examiner-Bernard A. Gilheany Assistant Examiner-Dewitt M. Morgan Attorney-Thomas E. Turcotte, James S. Nettleton, Donald W. Thomas, Burton H. Baker, Franklin C. Harter, Gene A. Heth and Hill, Sherman. Meroni. Gross & Simpson 57 ABSTRACT [56] References Cited 4C] 4m F I I res UNITED STATES PATENTS aw 3,164,729 1/1965 Holzer ..307/l41 J!" 7 L/fia 2A 3a a, s 34 .50 "Z3 42 a 64 3 a 2: 6 a? 54 22 513mm 47 4/ 5 J I? Z 24 45 5 5/ 45 i7 7 PATENTEU 1 I97? SHEET 2 OF 2 wic w /W 5 a M y We Wm. & 4C.

DRYER CONTROL CIRCUIT EMPLOYING TIMER HAVING TWO SPEEDS CROSS-REFERENCE TO RELATED APPLICATION This application is a division of my Ser. No. 836,465 filed June 25, 1969, now US. Pat. No. 3,571,945 issued Mar. 23, 1971.

BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to a clothes dryer having a control circuit for providing an anti-wrinkle cycle, and more particularly to a clothes dryer in which the control circuit provides an anti-wrinkle cycle under the control of a two-speed timer having a bimetal strip for connection in series with the dryer motor and for controlling the loads of operation of the timer.

2. Description of the Prior Art The provision of an anti-wrinkle cycle in the operation of laundry dryer apparatus is disclosed in U.S. Pat. No. 3,394,465 to Donald E. Janke, assigned to the same assignee as the present invention.

SUMMARY OF THE INVENTION According to the invention, laundry dryer apparatus includes a control circuit having a two-speed timer. The timer includes two camstacks, one of which is driven at a relatively rapid rate and the other of which is selectively and intermittently driven at a slow rate and has its driving connection, controlled by the first camstack. The first camstack operates contacts which are in series with a bimetallic strip and the dryer motor which revolves the dryer drum. The bimetallic strip is operable to provide a driving engagement between the second camstack and the timer motor in accordance with the heat generated by the current flowing through the bimetallic strip. Contacts of the second camstack are also provided in series with the bimetallic strip and dryer motor to provide operation of the dryer motor in the drying and cool down cycles; however, the shunt connection of contacts of the first camstack in this circuit provides for intermittent energization of the bimetallic strip and dryer motor during the anti-wrinkle cycle so that clothing within the drum will be fluffed during the anti-wrinkle cycle until such time as the intermittent engagement between the timer motor and the second camstack operates contacts to terminate the anti-wrinkle cycle.

A primary object of the invention is therefore to provide a dryer control having the advantages of two timers by the provision of a single timer motor and two camstacks, one of which is automatically and intermittently operated during an anti-wrinkle cycle in accordance with the operation of the other camstack, and to provide such apparatus at less cost than heretofore experienced with respect to individual components for providing similar types of operation.

BRIEF DESCRIPTION OF THE DRAWINGS Other objects, features and advantages of the invention, its organization, construction and operation, will be readily apparent from the. following description of a preferred embodiment thereof, taken in conjunction with the accompanying drawings, although variations and modifications may be efiected without departing from the spirit and scope of the novel concepts of the disclosure, and in which:

FIGS. 1 and 2 are horizontal elevational views, shown partially in cross section of a two speed timer which may be employed in practicing the present invention, FIG. 1 illustrating the timer in one mode of operation and FIG. 2 illustrating the timer in another mode of operation;

FIG. 3 is a schematic representation of a dryer control circuit in accordance with the principles of the present invention; and

FIG. 4 is a chart showing the condition of various timer operated switches particularly illustrating the drying, cool down and anti-wrinkle cycles.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring first to FIGS. 1 and 2, there is generally illustrated at 10 a timer having a two-section housing, the first section of which is defined by upper wall 20, lower wall 21 and

side walls

22 and 23. The second section of the housing is disposed immediately below the first section and is defined by upper wall 24, lower wall 25 and

side walls

26 and 27.

The upper housing includes a camstack 28 having cams 29-32 for operating contacts 33-36 in accordance with the predetermined program. Cams 29-32 are secured to a shaft 37 which is rotatably mounted to the lower wall 21 at 39 and extends through the upper wall 20 at aperture 39a to terminate in a manually operable dial knob 38. Upper wall 20 may be provided as a portion of the housing of the dryer appliance or may be disposed immediately behind such housing so that shaft 37 extends through the housing to place knob 38 on the exterior of the appliance in accordance with well known practice.

The upper housing section further includes a camstack 40 including a cam 41 for operating a set of contacts 42.

The lower housing includes a gear train 43 which is driven by a timer motor 44 secured to the exterior of lower wall 25. Timer 44 drives pinion 45 to transfer rotational motion to cam 41 by way of

gears

46, 47, and 48, gear 48 being rotatably mounted at 50 and 51 on shaft 49 which also carries cam 41.

The upper housing section further includes a bimetallic strip 52 secured in cantilevered fashion to mounting means 53 of lower wall 21. The passage of current through bimetallic element 52 effects a heating of that element and a downward bending of its distal end. Disposed immediately adjacent the distal end of element 52 is a plunger 54 which is mounted for rotational and axial movement in bearing 55 and aperture 56. Plunger 54 is biased toward the bimetallic element 52 by spring 57 bearing against the upper surface of lower wall 25 and the lower end of gear 58 carried by plunger 54. Gear 59 is also carried for rotation by plunger 54 and is placed in driving engagement with gear 45 upon downward movement of the distal end of element 52 (FIG. 2).

The engagement of

gears

45 and 59 transmit rotational motion to shaft 37 which carries cams 29-32 by way of

gears

45, 59, 58, 60, 64 and 65,

gears

60 and 64 being mounted for rotation on shaft 61 at 62 and 63 and gear 65 being co-rotatable with shaft 37.

Operation of timer motor 44 is therefore effective to continuously operate camstack 40, while operation of camstack 28 is dependent upon the driving engagement between

gears

45 and 59 due to the current through and resulting heating condition of bimetallic strip 52.

Turning now to FIGS. 3 and 4, connection of the aforedescribed timer with other elements to form a control circuit for a dryer is particularly exemplified. Conductors L1, L2 and L3 are, of course, provided in accordance with usual constructions of electric laundry drying apparatus. The heating portion of the circuit is generally connected across conductors L1 and L3, usually 240 volts, and includes the series connection of

switch contacts

33 and 36, heating element 74 and centrifugal switch 73. The remainder of the dryer circuit is connected across conductors L1 and L2, usually 120 volts, and includes a door operated switch 75, contacts 42 of camstack 40, bimetallic strip 52, dryer motor 165 and a start push button 70. The circuit also comprises contacts 35 connected in shunt relation to contacts 42, timer motor 44 connected between the door switch 75 and the start push button 70, and a relay winding 71 connected in shunt relation to the timer motor and having contacts 72 connected in shunt relation to the start push button 70 for maintaining the circuit energized upon release of the start button. The mechanical driving connections between the timer motor and the timer contacts are also shown by broken line, particularly the driving connection between the timer motor and cam 41 and between cam 41 and its associated contacts 42.

Dryer motor 165 includes a starting winding 66, a centrifugal switch 67 for removing the starting winding from the circuit at a certain motor speed and a running winding 68. Dryer motor 165 is coupled to rotate drum 69 which receives wet laundry. Of course, heating element 74 is employed to provide a heated flow of air through drum 69 as is well. recognized in the art.

Upon closure of door switch 75 and manual operation of dial knob 38 to close

contacts

33, 35 and 36, push button 70 is momentarily operated to complete an operating circuit for relay winding 71 over the path including line Ll, contacts 33, contacts 75, winding 71, switch 70 and line L2. Energization of winding 71 causes closure of contacts 72 to provide continuity of the electrical circuit to cross contacts 70 upon release of the push button. Electrical energy is also supplied by way of

contacts

33, 75 and 35 to bimetallic element 52 and

windings

66 and 68 of motor 65. The motor begins to rotate and upon reaching a certain speed contacts 67 remove winding 66 from the circuit. Centrifugal switch 73 operates to complete the circuit over

contacts

33 and 36 to energize heating element 74 so that drying may begin.

Energization of bimetallic strip 52 causes it to bend downwardly as illustrated in FIG. 2 thereby moving gear 59 into driving engagement with pinion gear 45. The main camstack 28 will therefore be operated to control the progress and termination of the drying cycle and the cool down cycle, as indicated in FIG. 4.

After the drying cycle of the program has been completed contacts 36 will be opened to open the energization circuit of the heating element 74. This terminates the drying cycle and initiates the cool down cycle. After a predetermined time contacts 35 will be opened to deenergize bimetallic element 52 and motor 165, however, timer motor 44 and relay 7] are not effected by contacts 35 and remain energized. Camstack 40 will therefore continue to operate. In a particular model of the timer, camstack 40 was advantageously operated so that cam 41 rotated at a speed of approximately 1/5 revolution per minute and was configured such that during each revolution contacts 42 were closed for approximately 10 seconds. As just mentioned, camstack 40 continues to operate; however, inasmuch as the bimetallic element 52 is not energized, gear 59 will be disengaged from gear 45 as shown in FIG. 1. Camstack 28 will therefore discontinue rotation.

Upon the closure of contacts 42 by cam 41 both the drive motor 165 and bimetallic element 52 will be energized and the dryer drum will begin to rotate. Downward bending of the bimetallic element 52 will again cause the engagement of gear 59 with pinion gear 45 so that camstack 28 will be operative. The closing of contacts 42 is only temporary and after a few seconds these contacts will open again. The dryer drum 69 will therefore stop again, as will the rotation of camstack 28. This action will continue until camstack 28 has rotated sufficiently to open switch 33 to deenergize the dryer completely.

Generally then there has been described a laundry dryer appliance which is provided with an anti-wrinkle cycle by the provision of a timer having two camstacks, one of which is continuously driven and the other of which is intermittently driven during the anti-wrinkle cycle in response to the operation of said one camstack and the resulting energization of a bimetallic cantilever which effects a driving engagement between the timer motor and the other camstack on an intermittent basis. The intermittent operation of the second mentioned camstack corresponds to intermittent operation of the dryer motor and drum during the anti-wrinkle cycle, the bimetallic element providing both the mechanical coupling of the second mentioned camstack to the timer motor and a series connected portion of the electrical circuit of the dryer motor, so that the dryer drum is intermittently operated during the anti-wrinkle cycle and the anti-wrinkle cycle is terminated at the end of a delayed time under the control of the intermittently operated camstack.

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. In a laundry drying apparatus including a rotatable drum and a drive motor for rotating said drum, a timer comprising a timer motor and a first and a second cam means, drive connection means coupling said first and second cam means to said timer motor, circuit means including switch means actuated by said first cam means and controlling the energization of said drive motor to operate the apparatus through a drying cycle of predetermined duration, a bimetallic element energizable by operation of said second cam means, and coupling means in said drive connection means responsive to the movement of said bimetallic element upon energization to engage said first cam means with said timer motor to thereby intermittently energize said drive motor upon completion of said drying cycle.

2. The drying apparatus of claim 1 which includes a heating means for heating the interior of said drum,

train to said first said cam means.

4. The drying apparatus of claim 3 in which said shaft carries a first gear means, and said timer motor drives a second gear means engageable with said first gear means upon movement of said bimetallic element, and said first cam means carries a third gear means engageable with said second gear means.

Claims

2. The drying apparatus of claim 1 which includes a heating means for heating the interior of said drum, said switch means operated by said first cam means including switch means to deenergize said heating means upon completion of said drying cycle.

3. The drying apparatus of claim 1 in which said drive connection means includes a gear train having an axially movable gear shaft engaging said bimetallic element and spring means urging said shaft in one axial direction, said bi-metallic element moving said shaft axially against said spring means to complete the gear train to said first said cam means.