US 5,847,636 A · Heat motor operated load regulating switch assembly

Abstract

A user adjustable switching controller for duty cycle regulating flow of current to an electrical load such as a resistance heater, particularly for cooking appliances. A load current switch, when closed by a user operated cam also energizes a heat motor which includes a resistive strip attached to one active leg of a U-shaped bi-metal member. The load current switch snap spring is attached to the heated leg of the bi-metal. The other leg of the U-shaped bi-metal is anchored to one of the load connecting stationary terminals and serves to provide ambient temperature compensation. User rotation of the cam deflects a bias spring which acts on the portion of the bi-metal attached to the load switch snap spring to effect closing of the load current switch and energization of the heat motor. Heating of the bi-metal causes warpage which overcomes the bias spring to open the load switch and shut off the heat motor. Cooling of the bi-metal allows the load current switch to re-close repeating the cycle. User adjustment of the cam varies the bias on the snap spring and thus the re-open point of the switch with respect to the cycle, thereby varying the ratio of "on" to "off" time of the load current.

Claims21

Dependent claims

A controller for duty cycling or regulating first and second electrical loads comprising:

(a) a housing structure;
(b) a switching structure associated with said housing structure and including a moveable switch member, operable upon movement to effect snap-action making and breaking of a first set of electrical contacts;
(c) a cam means operable upon user movement thereof to effect said movement of said switch member for said first set;
(d) a heat motor operative upon connection to a source of power to effect cycling of said movement of said switch member for said first set when said cam means has effected said member movement for making said first set of contacts, wherein said first set of electrical contacts is connected with said heat motor means and a first electric load and wherein a second set of contacts is also connected with said first electrical load and said power source;
(e) a third set of contacts series connected with a second electrical load and said second set of contacts;
and,
(f) said second and third sets of contacts are operated by said cam means.

4 more elements

A heat motor operated regulating switch assembly comprising:

(a) a base member having a projection extending therefrom;
(b) a bi-metal member having a U-shaped configuration and having an end of a first leg of said U-shape attached to said base member and extending in cantilever therefrom;
(c) a heater attached to said bi-metal member and operable upon electrical energization to effect warping of said bi-metal;
(d) a moveable contact member having a blade spring integrally formed therewith and extending from a first end thereof toward a second end distal said first end, said contact member having said second end registered on said base projection and having said blade spring having first portions connected to a second end of said bi-metal distal said bi-metal first end, said bi-metal having second portions connected intermediate the ends of said contact member, wherein said blade spring is placed in compression;
and, upon over-center movement thereof said blade spring effects a snap-action movement of said contact member wherein said first end of said contact member includes structure which functions as a moveable electrical contact;
and,
(e) a stationary contact disposed adjacent said moveable contact structure wherein, upon energization of said heater, said bi-metal moves said blade spring over-center and effects snap-actuation of said contact member in one direction, and upon de-energization of said heater, said bi-metal cools and effects snap-actuation of said contact member in a direction opposite said one direction.

4 more elements

Dependencies are inferred from the claim text.

Heat motor operated load regulating switch assembly

Life of this patent

Heat motor operated load regulating switch assembly

Life of this patent

Abstract

Claims21