US3614701A

US3614701A - Manually controlled delayed-action power switch

Info

Publication number: US3614701A
Application number: US3826A
Authority: US
Inventors: Donald J Gardner
Original assignee: Individual
Current assignee: Individual
Priority date: 1970-01-19
Filing date: 1970-01-19
Publication date: 1971-10-19
Anticipated expiration: 1988-10-19

Abstract

A manually controlled delayed-action power switch that an operator may position to cause immediate closing or opening of an electric circuit or alternatively set into motion a sequence of events which will cause the circuit to open after a predetermined delay effected by the properties of a thermal element.

Description

United States Patent Inventor Donald J. Gardner 3741 Penbrook Lane#13, Flint, Mich. 48507 I Appl. No. 3,826 Filed Jan. 19, 1970 Patented Oct. 19, 1971 MANUALLY CONTROLLED DELAYED-ACTION POWER SWITCH 9 Claims, 6 Drawing Figs.

US. Cl 337/341, 337/88 Int. Cl H0lh 37/62 Field ofSearch 337/8l,88,

[56] References Cited UNITED STATES PATENTS 2,769,053 10/1956 Weinfurt 337/81 3,284,597 11/1966 Hollis 337/88 3,123,686 3/1964 Leichsenring 337/88 Primary Examiner-Velodymyr Y. Mayewsky Assistant Examiner-F. E. Bell Attorney-Dennison and Dennison ABSTRACT: A manually controlled delayed-action power switch that an operator may position to cause immediate closing or opening of an electric circuit or alternatively set into motion a sequence of events which will cause the circuit to open after a predetermined delay effected by the properties of a thermal element.

PATENTEDUBT 19 I971 SHEET 10F 2 v INVENTOR DONALD J. GORZENSKI r 4% PATENTEDnm 19 I971 SHEET 2 BF 2 FIG. 4

INVENTOR DONALD J. GORZENSKI ATTORNEYS MANUALLY CONTROLLED DELAYED-ACTION POWER SWITCH In many residential and commercial environments it is desirable to use a switch that incorporates a delay feature to control power to a light, motor, etc. so that the device being controlled will receive current for a predetermined time after the operator tums the switch off. This requirement may be dictated by numerous safety reasons or simply a matter of convenience allowing a person to switch off a light in the garage or bedroom then leave the garage or enter bed before the extinguishes.

Prior delayed-action electrical power switches provided a means to manually complete an electrical circuit and when placed in the off position utilized a thermal element to delay opening the circuit a predetermined length of time. (See for example US. Pat. No. 3,123,686 issued to Leichsenring and U.S. Pat. No. 1,328,478 issued to Baker). These prior art switches, however, cannot open the circuit immediately if desired and when safety dictates or for convenience a second such switch must be incorporated in the circuit to allow immediate opening of the circuit. This invention overcomes the above drawback of prior delay switches by providing a switch that can be placed either in the delay mode or switched off immediately.

The present invention accomplishes the desired functions by providing a single-pole (rotor), three-position switch where one position is open or off, a second position completes the circuit and a third position completes the circuit but is spring loaded to the first or off position. When the switch is held in the spring-loaded position, current is supplied to the load via a heating element wrapped around a bimetallic element. When the bimetallic member is heated to a predetermined temperature, it makes contact with the rotor via the rotor spring, creating a second path for current to the load that remains closed after the control knob is released. When the bimetallic clement cools sufficiently, the contact with the spring opens removing power from the load.

One object of the invention is to provide a new and improved delayed-action power switch which may be turned off immediately or operated in a delayed action mode and is well adapted for general residential and similar usages, and having an inherent practicality by virtue of being well adapted for economical manufacture and having an inherent capability of operating dependably and efficiently.

Another object is to provide a delayed-action power switch as recited in the preceding object which occupies a small space.

Another object is to provide a compact two-mode switch adapted to couple an ordinary electric plug to an ordinary electric connector or tap, and having an extremely economical construction which provides response to operation of a manual control on the coupling to provide an efficient and dependable opening of the circuit through the coupling in a manner described in relation to the preceding objects.

Another object is to provide a novel switch connector of small size having in combination an ordinary electric socket for incandescent light bulbs.

Another object is to achieve the objects previously recited by means of structure in which the working parts which effect the delayed opening are confined essentially to a simple bimetallic element.

A still further object of the invention is to provide a twomode switch as previously stated which has a minimum number of parts, requires little or no maintenance, is inexpensive to produce and is safe and reliable in use.

Other objects and advantages will become apparent from the following description of the exemplary forms of the invention illustrated in the drawings, in which:

FIG. 1 is top sectional view of the switch taken along line 1-1 of FIG. 2;

FIG. 2 is a side elevation of the switch of FIG. 1 with some parts shown in section;

FIG. 3 is an exploded view of the switch-operating elements;

FIG. 4 is a schematic diagram load; I

FIG. 5 is a perspective of the switch installed in an incandescent light socket; and

FIG. 6 is an alternate embodiment of the switch installed in a housing and completing an electric circuit between an electric plug and socket.

Referring to the drawings in greater detail wherein like parts are represented by like reference characters, the switch is shown generally at 10 and includes a preferably cylindrical casing 11 which may be made of an insulating material such as plastic. The casing is closed by circular top wall 12, but is open on the bottom and provided with an annular tapered shoulder 13. Due to the rather thin construction of the casing and since it is manufactured from plastic, the side wall is somewhat resilient and the annular shoulder 13 provides a retaining means for receiving a switch-mounting plate 14, as shown best in FIG. 2. The mounting plate 14 is preferably stamped from metal and will be frictionally retained above the shoulder 13.

A shaft opening is provided in the top wall 12 and is surrounded by boss 15 for joumaling the manual-operating shaft 16. Shaft 16 terminates in an integrally formed knob 17 and its opposite end is internally bored to receive the parts of the switch to be rotated. The shaft and

knob

16 and 17 are preferably molded from plastic material.

A bifurcated switch rotor 20 is mounted to the spaced from the mounting plate 14 for rotary motion by means of a cylindrical spacer 21 having a reduced-diameter neck 22 adapted to be rotatably received within the central hole 23 on the base plate 14. A resilient snap ring or spring clip 24 fits in an annular groove in neck 22 as shown in FIG. 2 and serves to restrain the spacer 21 from axial movement but allows rotation.

In order to impart rotation when desired to the rotor 20, an upper spacer 25 provided with a flat side 26 is mounted directly above the rotor 20 and is secured thereto by means of a bolt 27 adapted to pass through a bore 28 in the spacer 25, then through bore 29 in the rotor 20, and adapted to be threadedly received in the tapped opening 30 of the spacer 21. It will be understood that the plastic rotor shaft 16 will have a flat portion so that rotation of the hand knob 17 will not cause relative slippage between the shaft 16 and the spacer member 25.

It will be understood that the rotor 20 and the

spacers

21 and 25 may be formed as an integral piece if desired for sake of economy of manufacture.

The bifurcated rotor 20 is formed with

electrical contacts

31 and 32 on each of the arms thereof as best seen in FIGS. 1, 2 and 3. The arms are bent vertically with respect to each other so that the contact 31 is preferably at a level somewhat above that of the contact 32 as can be seen in FIG. 2 in order to provide clearance over the bimetallic element when space is a problem in smaller units.

Other elements of the switch are mounted on the base plate 14 in the following fashion and for a purpose to be later described.

A flat spring detent member 35 is tightly wrapped about a mounting pin at one end thereof shown at 36. The pin is adapted to be secured to the mounting plate 14 through a mounting opening 37. Mounting may be achieved by deforming the head of the pin 36 or by any other conventional means.

An elongated rotor biasing spring 38 has an eye at one end 39 adapted to be received about a pin 40 depending from one of the arms of the rotor 20. The spring is then bent so as to pass about the spacer 21 and has an electrical contact 41 mounted thereon intermediate the ends of the spring and the spring then terminates in an eye 42 which tightly receives a mounting pin 43 received in the opening 44 of the mounting plate 14. The mounting pin 43 may be secured within the opening 44 in a manner similar to the pin 36.

A conventional bimetallic element 50 formed of laminated bands of dissimilar metals in a manner known in the art is curved in a manner shown in FIGS. 1 and 3 and is secured to the baseplate 14 by means of a mounting block 51. In order to of the switch circuit with a insulate the mounting block 51 from the mounting plate 14, an insulating pad 52 is interposed between the two elements, a contact screw 53 serves to secure the mounting block 51 to the plate 14 and the same passes through an insulating grommet 54 received in the mounting hole 55. It will be understood as seen in FIG. 3 that screw 53 constitutes a terminal mount for reception of the stripped end of a wire conductor leading to the load L. A switch contact member 56 is mounted on the terminal mounting block 51 but is spaced therefrom by an insulating pad 57. A metalic wire such as nichrome is secured to the contact 56 and then is coiled about the bimetallic element 58 throughout its extent and is secured to the opposite end thereof at 59. Opposite the attachment of the wire 59, a contact pad 60 is provided on the front surface of the bimetallic element adapted to make contact with the electrical contact member 41 mounted on the spring 38. Under normal conditions, and normal temperatures, the

contacts

60 and 41 are spaced as shown in FIG. 1. It is only when the nichrome wire is heated and the bimetallic element 58 flexed that these contacts touch.

An electrical contact 61 is mounted on the opposite face of the mounting block 51 and is in direct electrical connection therewith. This contact is adapted to be engaged by the contact 32 on the rotor arm in one position of rotation of the switch.

A terminal-mounting screw 65 is received in a threaded hole 66 on the mounting plate to provide connection to the other side of the circuit. As shown in FIG. 3 an access hole 70 is formed in the plate 14 as later described.

FIG. 1 illustrates the switch in the on position. To turn the switch off, the knob 17 is turned counterclockwise and released. This action rotates the rotor 20 which impedes further rotation of the knob 17 when contact 31 meets contact 56. Releasing the knob 17 allows the spring 38 to rotate knob 17 and rotor 20 clockwise until pin 40 contacts detent spring 35. The interaction between

springs

38 and 35 hold the rotor so that

contacts

31 and 32 are centered about mounting block 51 and no path for current is provided through the switch.

"To move the switch from the off position to the on position illustrated in FIG. 1, the knob 17 is rotated clockwise forcing pin 40 past the detent spring 35 which allows spring 38 to hold the rotor so that contact points 32 and 61 are closed. Referring to the schematic diagram, FIG. 4, it can be seen that current will now flow from the power source 88 through lead 85 to the load L and from the load to terminal 65, through

contacts

32 and 61 to terminal 53 which is connected to wire 86 forming a return to the power source 88. Leads 85 and 86 are the wires of a standard two-wire electrical cable 87 of the type normally used to connect electrical appliances and lamps to electrical outlets. The electrical connection between terminal 65 and contact 32 is provided by the baseplate 14, spacer 21 and rotor 20, see FIG. 3. The electrical connection between contact 61 and terminal 53 is provided by mounting block 51 which is insulated from the baseplate 14 by insulating pad 52. Terminal 53 is insulated from the baseplate 14 by insulating grommet 54 but is in electrical contact with mounting block 51.

Holding the knob 17 in the extreme counterclockwise position activates the delay means by providing an alternate path for current through switch, see FIGS. 1 and 4. This path for current is from the source 88 through lead 85 to the load L then to terminal 65, through the switch plate 14, spacer 21, and rotor 20 to contact 31, then to contact 56. From contact 56 current flows through the heating wire means 58 to connection 59 on the bimetallic element 50, then through the bimetallic element to terminal 53 via mounting block 51. Current is returned to the source from terminal 53 as previously explained. The heat generated by heating wire means 58 causes the bimetallic element 50 to deflect until restricted by contact 60 on the bimetallic element contacting contact 41 on spring 38. This provides another path for current through the switch; from terminal 65 through spring 38 to contact 41 and from 41 to contact 60 through the bimetallic element 50 to terminal 53. This path parallels the path of current through the heating wire means 58 such that when the knob 17 is released and the switch rotor moves to the off position as previously described, current will continue to flow through the load.

Contacts

41 and 60 remain mated until the bimetallic element 50 cools sufficiently to uncoil. It will be appreciated that the delay in disconnecting the load from the power source is a function of how long it takes the bimetallic element 50 to cool to a predetermined temperature. The longer the knob 17 is held in the extreme counterclockwise position, the greater the temperature of the bimetallic element 50. Hence the duration of delay depends on how long the knob is held counterclockwise. The temperature at which

contacts

41 and 60 open is controlled by physically bending the bimetallic element 50 about its connection with mounting block 51. This is accomplished by inserting an insulated screwdriver or similar insulated means through the access hole 70 in the switch mounting plate 14 and applying pressure to the bimetallic element to cause it to bend in the desired direction. It can be seen in FIG.

1 that the heating wire means 58 is not wrapped around the bimetallic element 50 in the area of the hole 70 to minimize the danger of breaking the heating wire means 58 during adjustment.

FIG. 5 is a preferred embodiment of the invention where the switch 10 is contained in an ordinary light socket 5. In this embodiment, the rotor spacer 21 makes contact with center contact of the bulb B and the two

wires

85 and 86 of the electric cable 87 are connected to terminal 53 of the switch and the threaded portion of the socket. FIG. 6 is an alternate embodiment of the switch illustrating its incorporation in a standard electrical extension cord. This embodiment consists of a power source plug 81 which is connected to the switch 10 via a two conductor electrical cable 87. The switch 10 is mounted in a housing made of an insulating material such as plastic. A standard outlet receptacle 82 is connected to the switch by a second length of standard two conductor electrical cable 83.

Cables

83 and 87 may be one continuous cable with one of the conductors cut and the severed ends connected, one to terminal 53 and one to terminal 65 of the switch 10. It is to be understood that either the plug 88 or receptacle 82 or both may be incorporated as part of the switch housing 80.

What I claim as my invention and desire to protect by letters patent of the United States is:

1. An electrical switch for use in a circuit having a power source and a load and having a normal shutoff mode and a time delay shutoff mode comprising in combination:

a. a rotatable conductive member having first and second electrical contacts thereon; third and forth electrical contacts adapted to be engaged by said first and second contacts respectively, to complete a circuit between the power source and the load;

c. first spring means normally urging said rotatable member to a position wherein said second and fourth electrical contacts are engaged establishing the on position of said switch;

d. second spring means acting to prevent rotation of the rotatable member so that the contacts thereon are out of engagement with either of the third and fourth contacts establishing the normal shutoff mode;

e. a bimetallic element having a switch contact at one end thereof, and in electrical communication with said fourth contact;

. contact means in electrical communication with said rotatable member normally spaced from said switch contact of said bimetallic element; and

a heating coil wrapped about said bimetallic element and connecting said third contact and said switch contact,

whereby rotation and temporary holding of said rotatable member with said first and third contacts engaged passes current from said source through said heating coil thereby deforming the bimetallic element so that the switch contact and contact means are in engagement passing current to the load until the bimetallic element cools establishing the time delay mode of operation.

2. A switch as defined in claim 1 wherein said first spring means is a bent flat detent spring and a pin depending from said rotatable member engaging said detent spring.

3. A switch as defined in claim 1 and further including a conductive mounting plate, said rotatable member extending through said plate for rotation with respect thereto, said rotatable member being in electrical communication with said mounting plate and a terminal in communication with said plate.

4. A switch as defined in claim 3 and further including a terminal block mounted on said plate but insulated therefrom, said third and fourth contacts being mounted on said terminal block with said third contact being insulated therefrom and said fourth contact in electrical communication therewith, and a second terminal electrically connected to said terminal block.

5. A switch as defined in claim 1 and further including a housing and a hand knob extending into said housing and secured to said rotatable member for imparting rotation thereto.

6. A switch as defined in claim 4 and further including an access hole in said mounting plate for insertion of a tool to manually deform the bimetallic element in order to adjust the time delay.

7. A switch as defined in claim 5 wherein said housing is in the form of an electric socket having a threaded-female portion for receiving a light bulb.

8. A switch as defined in claim 5 wherein said housing is in the form of an electrical outlet having a standard two conductor female socket.

9. A switch as set forth in claim 4 wherein said contact means comprises a metal contact member mounted on said second spring means.

Claims

1. An electrical switch for use in a circuit having a power source and a load and having a normal shutoff mode and a time delay shutoff mode comprising in combination: a. a rotatable conductive member having first and second electrical contacts thereon; b. third and forth elEctrical contacts adapted to be engaged by said first and second contacts respectively, to complete a circuit between the power source and the load; c. first spring means normally urging said rotatable member to a position wherein said second and fourth electrical contacts are engaged establishing the on position of said switch; d. second spring means acting to prevent rotation of the rotatable member so that the contacts thereon are out of engagement with either of the third and fourth contacts establishing the normal shutoff mode; e. a bimetallic element having a switch contact at one end thereof, and in electrical communication with said fourth contact; f. contact means in electrical communication with said rotatable member normally spaced from said switch contact of said bimetallic element; and g. a heating coil wrapped about said bimetallic element and connecting said third contact and said switch contact, whereby rotation and temporary holding of said rotatable member with said first and third contacts engaged passes current from said source through said heating coil thereby deforming the bimetallic element so that the switch contact and contact means are in engagement passing current to the load until the bimetallic element cools establishing the time delay mode of operation.