Electric power controllers

Abstract

A power controller for controlling the intermittent supply of current to a load, such as a cooker hotplate, has a pivotally mounted snap switch controlled by a heated bimetal member which is heated in dependence upon the connected power. A compensating bimetal strip, for taking ambient temperature into account, is arranged on the snap switch and parallel thereto. A control cam acts on the free end of the compensating bimetal strip. The latter is shielded from the heat of the heated bimetal member.

We claim: .[.1. A power controller for the controllable supply of electrical power intermittently to a load, comprising: 
     
        pivots is received..]. .[.8.  A controller according to claim 7, in which one of the housing parts has a cavity which accommodates said snap switch, said bimetal member, said heating means and said compensating bimetal strip, and the other of said housing parts comprising a cover which substantially closes off said cavity..]. .[.9. A controller according to claim 1, in which said control cam means has a rotatable adjusting shaft and in which a mechanical mains switch is arranged in said housing substantially in the same plane as said snap switch and said bimetal member..]. .[.10. A controller according to claim 9, in which said mains switch has a switch slide and transversely extending contact arms thereon and in which said control cam means includes a cam for actuating said switch slide..]. .[.11. A controller according to claim 10, in which said housing is rectangular or square and in which said switch slide lies diagonally in a corner of said housing..]. .[.12. A controller according to claim 10 in which said switch slide comprises insulating material and in which at least four metallic guides arranged opposite one another in pairs are provided in said housing and extend at right angles to said switch slide for guiding said switch slide, said guides defining thereon fixed contacts with which said contact arms co-operate and protruding through said housing to define connecting tabs..]. .[.13. A controller according to claim 1, in which said control cam means combines a control body which has a control cam thereon, and an adjusting shaft which is received in a hole in said control body and protrudes from the housing at the operating side thereof, and in which the housing has a bearing opening at its side remote from the operating side and said control body has an integrally moulded bearing pin which is journalled in said bearing opening..]. .[.14. A controller according to claim 1, which is adapted to operate with alternating current and which further comprises a diode and auxiliary switch means actuable by said control cam means for connecting said diode in circuit with said heating means for said bimetal member, only in an upper power range but not in a lower power range..]. .[.15. A controller according to claim 2 in which an adjusting screw is associated with said longer limb and spring means is provided for biassing said 
     
     
        longer limb against said housing via said adjusting screw..]. .[.16.  A controller according to claim 6 in which said compartment is provided with heat shield means..]. .[.17. A controller according to claim 6 in which said compartment is provided with ventilating means..]. .[.18. A controller according to claim 14 in which said diode is located on a rear side of said housing remote from the operating side thereof and is disposed directly on said auxiliary switch means..]. .[.19. A controller according to claim 18 in which said control cam means combines a control body which has a control cam thereon, and an adjusting shaft which is received in a hole in said control body and protrudes from the housing at the operating side thereof, and in which the housing has a bearing opening at its side remote from the operating side and said control body has an integrally moulded bearing pin which is journalled in said bearing opening..]. .[.20. A controller according to claim 19, in which said bearing pin on said control body defines thereon a switching cam for said auxiliary switch means..]. .Iadd. 21. A power controller for the substantially stepless manual control of electrical a.c. power comprising: a housing in, and on which all components of the power controller are disposed;   power switch means for a load;   a bimetal member for intermittently operating said power switch means;   ambient temperature compensating means for heating said bimetal member in dependence upon power supplied to said load via said power switch means;   manually operable control means acting on said bimetal member;   a diode for limiting power to said heating means;   auxiliary switch means, actuable by said control means, for enabling manual switching of said diode in circuit with said heating means only in an upper power range, said heating means receiving only half wave power in an upper range but receiving full wave power in a lower power range;   a cam forming part of said manually operable control means and including a sloped operating surface which compensates for a control discontinuity due to said switching of said diode when manually adjusting the control means between the upper and lower power ranges, whereby substantially stepless control is achieved despite the intermittent switching of the power. .Iaddend. .Iadd. 22. A controller according to claim 21, wherein said diode is in series with said heating means and said auxiliary switch means is in parallel with said diode for shunting said diode in said lower power range. .Iaddend..Iadd. 23. A controller according to claim 21, wherein said diode is located on a rear side of said housing remote from the operating side thereof and is disposed directly on said auxiliary switch means. .Iaddend..Iadd. 24. A controller according to claim 23 wherein said control means comprises a control body which has a control cam thereon, and an adjusting shaft which is received in a hole in said control body and protrudes from the housing at the operating side thereof, and wherein the housing has a bearing opening at its side remote from the operating side and said control body has an integrally molded bearing pin journalled in said bearing opening, said bearing pin on said control body defining thereon a switching cam for said auxiliary switch means. .Iaddend.