Imported: 21 Feb '17 | Published: 01 Mar '05
USPTO - Utility Patents
A timer for delaying the operation of a toggle switch for a pre-set interval includes a mechanical, spring powered timer which drives a cam that engages the toggle of a conventional wall switch to move the toggle from one position to another. The timer is contained within a housing which, in turn, detachably connects to a housing floor that is mounted over the toggle switch cover plate.
This application claims the benefit of U.S. Provisional Patent Application No. 60/450,802 that was filed on Feb. 27, 2003.
1. Technical Field
This invention relates to a mechanical delay timer that is arranged to turn a toggle switch on or off after a predetermined interval.
More particularly, this invention relates to a delay timer that may be mounted upon a conventional wall switch without modification of the switch in any way.
2. Description of Related Art
There are a number of mechanical and electrical devices known in the prior art that function to turn a switch on or off at a preset time or after a delay interval. Examples of such prior art devices include those described in U.S. Pat. Nos. 5,719,362; 4,912,376; 4,835,413; 3,818,156; 3,179,396; 2,937,247 and 1,922,868. However, none of the known prior art devices offer the convenience, ease of installation, and simple mechanical dependability as does the timer disclosed herein.
The delay timer of this invention includes a mechanical, spring-driven timer means that is arranged to impart rotary movement to a cam plate. A pair of upstanding rails are spaced apart on a surface of the cam plate to define a spiral cam track that accepts the lever of a conventional toggle switch. Rotation of the cam plate imparted by the timer causes the toggle switch lever to move downward or upward within the cam track to thereby turn the switch off or on after a preset interval. The timer means and cam plate are mounted within a housing that preferably snap-connects to a housing floor, or base, which in turn is attached to an existing switch plate using the switch plate mounting screws for attachment.
It is therefore an object of this invention to provide a simple and reliable delay timer that can be easily mounted upon an existing toggle switch without modification or disassembly of the switch.
Other objects and advantages of this invention will become evident from the following disclosure and description of certain preferred embodiments.
The delay timer of this invention will be described with reference to the Figures wherein FIG. 1 shows the delay timer generally at 10. Timer 10 includes an external housing 12 having a timer set control 14 on the front thereof. As is better illustrated in FIGS. 2 and 3, rotation of set control 14 serves to tension the power spring 16 of timer means 18. Timer means 18 may conveniently comprise the same operating mechanism as is used in kitchen and other short-interval timers. Alternatively, the timer means 18 may comprise a spring driven music box, and may be arranged such that the music ends as the toggle switch lever turns the switch off or on.
A cam plate 20 is fixed to and is caused to rotate at a pre-determined rate by timer means 18 upon tensioning of the power spring 16 by rotation of the set control. Cam plate 20 is preferably circular, and is provided with a flat surface 22 having a pair of upstanding cam rail means 24 fixed thereto. Cam rails 24 are arranged to form an inwardly spiraling, constant width, cam track 26, which is best seen in FIG. 5. The cam rails 24 are spaced such that the lever 30 of a conventional toggle switch fits loosely there between and is caused to move downwardly or upwardly as the cam plate rotates.
The delay timer of this invention is shown mounted to a conventional household toggle switch in the partially cut-away view of FIG. 3. The exterior housing 12 preferably includes a detachable back member 32 that is constructed to snap on and off of the main part of the housing. Back member 32 is provided with holes that align with the mounting screws 36 for switch plate 35 and is provided as well with an opening for toggle switch lever 30 to extend therethrough. Back member 32 is attached to the switch plate 35 using mounting screws 36. Housing 12 is then snapped into place on the back member making sure that the toggle switch lever 30 is engaged within the track defined by rails 24.
FIG. 6 shows another embodiment of cam plate 20. In this embodiment, the pair of cam rails 24, shown in FIG. 5, is replaced by a single, continuous, upstanding rail 40 that spirals inwardly from the edge of the cam plate toward its center so as to form a cam channel or track 41 of constant width. This embodiment offers advantage in that it avoids installation error.
As may be appreciated from the foregoing description, this invention provides a simple and versatile delay timer that can easily be installed to operate in association with conventional toggle wall switches. It has been described in relation to preferred embodiments thereof that are illustrated in the drawing Figures. It is to be understood that variations and modifications of the invention, other than those specifically described, will be apparent to those skilled in the art and are included within the scope of the invention.