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Title: Solid state stack switch control system
Claims: What is claimed is: 1. In a stack control system for furnaces, the combination including burner control means adapted to be connected to a main line source of AC current, a low voltage control circuit including thermally activated, magnetically operated heat detection means, said heat detection means including a bimetallic actuating member movable in response to thermal changes, a reed switch, and magnetic means movable in response to movement of said actuating member and effective to actuate said reed switch, said magnetic means including a magnetic body defining an opening therethrough, a drive arm formed of magnetic material and extending through the opening defined by said magnetic body whereby said magnetic body is magnetically clutched to said drive arm, one end portion of said drive arm being fixed to said actuating member, stop means limiting movement of said magnetic body relative to said reed switch while permitting de-clutching of said magnetic body with respect to said drive arm and continued movement of said drive arm relative to said magnetic body, means in said low voltage control circuit including solid state means effective to actuate said burner control means, circuit interrupting means effective to interrupt the flow of current from said main line source of AC current, and means controlled by said heat detection means controlling the actuation of said circuit interrupting means. 2. In a stack control system for furnaces, the combination including burner control means adapted to be connected to a furnace burner connected to a main line source of AC current, a low voltage control circuit including thermally actuated, magnetically operated heat detection means, said heat detection means including a bimetallic actuating member movable in response to thermal changes, a reed switch, and magnetic means movable in response to movement of said actuating member and effective to actuate said reed switch, said magnetic means including a magnetic body defining an opening therethrough, a drive arm formed of magnetic material and extending through the opening defined by said magnetic body whereby said magnetic body is magnetically clutched to said drive arm, one end portion of said drive arm being fixed to said actuating member, stop means limiting movement of said magnetic body relative to said reed switch while permitting de-clutching of said magnetic body with respect to said drive arm and continued movement of said drive arm relative to said magnetic body, means in said low voltage control circuit including solid state means effective to actuate said burner control means, circuit interrupting means controlled by said heat detection means and effective to control the flow of current from said main line source of AC current, and means interfacing between said low voltage control circuit and said burner control means. 3. In a stack control system for furnaces, the combination including burner control means adapted to be connected to a main line source of AC current, a low voltage control circuit including thermally actuated, magnetically operated heat detection means, said heat detection means including an elongate tubular body defining an axially extending passageway, one end portion of said tubular body being adapted to project into a furnace stack, a bimetallic actuating member of sinuous configuration mounted in said passageway in said one end portion of said tubular body, said bimetallic actuating member being movable in response to changes in temperature, a reed switch mounted in said passageway at a position remote from said one end portion of said tubular body, magnetic means disposed adjacent said reed switch and movable in response to movement of said actuating member to actuate said reed switch, said magnetic means including a magnetic body defining an opening therethrough, a drive arm formed of magnetic material and extending through the opening defined by said magnetic body whereby said magnetic body is magnetically clutched to said drive arm, one end portion of said drive arm being fixed to said actuating member, means for manually moving said drive arm, stop means limiting movement of said magnetic body relative to said reed switch while permitting de-clutching of said magnetic body with respect to said drive arm and continued movement of said drive arm relative to said magnetic body, means in said low voltage control circuit including solid state means effective to actuate said burner control means, circuit interrupting means effective to interrupt the flow of current from said main line source of AC current, and means controlled by said heat detection means controlling the actuation of said circuit interrupting means. 4. In a stack switch control assembly, the combination including an elongate tubular body defining an axially extending passageway, one end portion of said body being adapted to project into a furnace stack, a bimetallic actuating member mounted in said passageway in said one end portion of said body, said bimetallic actuating member being movable in response to changes in temperature in a furnace stack, a reed switch mounted in said passageway at a position remote from said one end portion of said body, magnetic means mounted in said passageway adjacent said reed switch and movable in response to movement of said actuating member to actuate said reed switch, said magnetic means including a magnetic body defining an opening therethrough, a drive arm formed of magnetic material and extending through the opening defined by said magnetic body whereby said magnetic body is magnetically clutched to said drive arm, one end portion of said drive arm being fixed to said actuating member, and stop means limiting movement of said magnetic body relative to said reed switch while permitting de-clutching of said magnetic body with respect to said drive arm and continued movement of said drive arm relative to said magnetic body. 5. In a stack switch control assembly, the combination including an elongate tubular body defining an axially extending passageway, one end portion of said tubular body being adapted to project into a furnace stack, a junction box, resilient means releasably connecting the other end portion of said tubular body to said junction box, a bimetallic actuating member of sinuous configuration mounted in said passageway in said one end portion of said tubular body, said bimetallic actuating member being movable in response to changes in temperature in a furnace stack, a reed switch mounted in said passageway at a position remote from said one end portion of said body, magnetic means mounted in said passageway adjacent said reed switch and movable in response to movement of said actuating member to actuate said reed switch, said magnetic means including a magnetic body defining an opening therethrough, a drive arm formed of magnetic material and extending through the opening defined by said magnetic body whereby said magnetic body is magnetically clutched to said drive arm, one end portion of said drive arm being fixed to said actuating member, means for manually moving said drive arm, and stop means limiting movement of said magnetic body relative to said reed switch while permitting de-clutching of said magnetic body with respect to said drive arm and continued movement of said drive arm relative to said magnetic body. 6. The combination as set forth in claim 5, said stop means engaging said magnetic body intermediate the ends thereof. 7. The combination as set forth in claim 5, said means for manually moving said drive arm including a lever fixed to said drive arm and projecting radially outwardly from said tubular body. Other info: Inventors: Bauer, Frederick T. (Holland, MI, US) Cairo, Anthony C. (Holland, MI, US) Holkeboer, Ronald E. (Holland, MI, US) Tyler, Gary E. (Wyoming, MI, US) Application Number: 482203 Filing Date: 1974-06-24 Publication_date: 1976-01-27 Assignee: Robertshaw Controls Company (Richmond, VA) Primary Class(es): 307/117 431/78 Other Classes: US Patent Ref:
Other Refs: Primary Examiner: Scott, James R. Assistant Examiner: Ginsburg, M. Attorney: McKinnon; Malcolm R. |
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