US3571945A

US3571945A - Dryer control circuit employing timer having two speeds

Info

Publication number: US3571945A
Application number: US836465A
Authority: US
Inventors: Alvin J Elders
Original assignee: Whirlpool Corp
Current assignee: Whirlpool Corp
Priority date: 1969-06-25
Filing date: 1969-06-25
Publication date: 1971-03-23
Anticipated expiration: 1988-03-23

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 antiwrinkle cycles.

Description

United States Patent Alvin .l. Elders Stevensville, Mich. 836,465

June 25, 1969 Mar. 23, 1971 Whirlpool Corporation Benton Harbor, Mich.

Inventor Appl. No. Filed Patented Assignee DRYER CONTROL CIRCUIT EMPLOYING TIMER HAVING TWO SPEEDS [56] References Cited UNITED STATES PATENTS 3,286,359 11/1966 Orr et al. 34/53X 3,394,465 7/1968 Janke 34/45 Primary Examiner-Carroll B. Dority, Jr,

Att0meysThomas E. Turcotte, James S. Nettleton, Donald W. Thomas, Burton H. Baker, Franklin C. Harter, Gene A. Beth and Hill, Sherman, Meroni, Gross and Simpson ABSTRACT: A dryer control includes two camstacks, one

operating continuously with the timer motor and the otherdriven 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 providetwo modes of operation in a dryer program having drying, cool down and antiwrinkle cycles.

DRYER CONTROL CIRCUIT EMPLOYING TIMER HAVING TWO SPEEDS BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to a clothes dryer having a control circuit for providing an antiwrinkle cycle, and more particularly to a clothes dryer in which the control circuit provides an antiwrinkle 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 1 The provision of an antiwrinkle cycle in the OF 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 antiwrinkle cycle so that clothing within the drum will be fluffed during the antiwrinkle cycle until such time as the intermittent engagement between the timer motor and the second camstack operates contacts to terminate the antiwrinkle 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 andtwo camstacks, one of which is automatically and intermittently operated during an antiwrinkle 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 effected 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 antiwrinkle cycles.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring first to FIGS. 1 and 2, there is generally illustrated at 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

sidewalls

26 and 27.

The upper housing includes a camstack 28 having earns 29- -32 for operating contacts 3336 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 M.

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 and 64, gears 60 and 64 being mounted for rotation on shaft 61 at 62 and 63. I

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 Ll, 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 LI and L2, usually I20 volts, and includes a door operated switch 75, contacts 42 of camstack 40, bimetallic strip 52, dryer motor 65 and a start pushbutton 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 pushbutton 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 pushbutton 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 4I and between cam 41 and its associated contacts 42.

Dryer motor 65 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 65 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, pushbutton 70 is momentarily operated to complete an operating circuit for relay winding 71 over the path including line L], 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 pushbutton. 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 apredetermined time contacts 35 will be opened to deenergize bimetallic element 52 and motor 65; however, timer motor 44 and relay 71 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 one-fifth revolution per minute and was configured such that during each revolution contacts 42 were closed for approximately 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 65 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 antiwrinkle cycle by the provision of a timer having two camstacks, one of which in continuously driven and the other of which is intermittently driven during the antiwrinkle 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 antiwrinkle 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 dur' ing the antiwrinkle cycle and the antiwrinkle cycle is terminated at the end of a delayed time under the control of the intermittently operated camstack.

I claim:

1. Laundry drying apparatus comprising a rotatable drum, a drive motor for rotating said drum, and a timer for controlling the energization of said drive motor, said timer including a timer motor, first switching means operated by said timer motor for operatively connecting said drive motor to an electrical supply for a first portion ofa predetermined drying program, second switch means connected for receiving electrical energy from said first switch means and ogeated by staid ltimer l'lVC mo or 0 an motor for intermittently connecting sat electrical supply, and a drive control means connected to said second switch means and intermittently energized by the operation thereof to engage and disengage said first switching means and said timer motor and thereby delay disconnection of said second switch means from the electrical supply and provide an antiwrinkle portion of the program by permitting intennittent energization of said drive motor during a second portion of said program.

2. Laundry drying apparatus according to claim I wherein said first switching means comprises a first camstack including a plurality of rotatable cams and a plurality of contacts associated with individual ones of said cams, a first of said contacts being operable to connect said second switching means to an electrical supply and a second of said contacts being operable to connect said drive motor to the electrical supply, and a second camstack including at least one rotatable cam and a corresponding third contact operable to intermittently connect said drive motor to the electrical supply, and said drive control means including an electromechanical device connected in series with said third contacts and said drive motor and mechanically coupled between said timer motor and said first camstack.

3. Laundry drying apparatus according to claim 2 wherein said electromechanical device includes a cantilevered energizable bimetallic member operable to bend upon the passage of current therethrough, and coupling means for coupling said bimetallic member to said timer motor and said first camstack.

Claims

1. Laundry drying apparatus comprising a rotatable drum, a drive motor for rotating said drum, and a timer for controlling the energization of said drive motor, said timer including a timer motor, first switching means operated by said timer motor for operatively connecting said drive motor to an electrical supply for a first portion of a predetermined drying program, second switch means connected for receiving electrical energy from said first switch means and operated by said timer motor for intermittently connecting said drive motor to an electrical supply, and a drive control means connected to said second switch means and intermittently energized by the operation thereof to engage and disengage said first switching means and said timer motor and thereby delay disconnection of said second switch means from the electrical supply and provide an antiwrinkle portion of the program by permitting intermittent energization of said drive motor during a second portion of said program.

2. Laundry drying apparatus according to claim 1 wherein said first switching means comprises a first camstack including a plurality of rotatable cams and a plurality of contacts associated with individual ones of said cams, a first of said contacts being operable to connect said second switching means to an electrical supply and a second of said contacts being operable to connect said drive motor to the electrical supply, and a second camstack including at least one rotatable cam and a corresponding third contact operable to intermittently connect said drive motor to the electrical supply, and said drive control means including an electromechanical device connected in series with said third contacts and said drive motor and mechanically coupled between said timer motor and said first camstack.