Bimetal controlled actuator
First Claim
1. A pressure transducer for producing a variable fluid pressure level from at least one pressure source corresponding to the level of a varying electrical signal input, the pressure transducer comprising:
- an enclosure having an interior chamber;
means creating a controllable communication with said interior chamber including;
a valve port and at least one heated bimetal actuator operatively associated with said valve port, said heated bimetal actuator including a bimetal arm biased into engagement with said valve port and including means sealingly engaging said bimetal arm and said valve port;
heater circuit means for heating said bimetal arm causing said bimetal arm to deflect away from said valve port allowing communication of said at least one pressure source with said interior chamber of said enclosure;
means activating said heater circuit whenever the pressure level in said interior chamber varies from correspondence with said varying electrical input signal in a direction tending to be corrected by communication of said at least one pressure source with said interior chamber;
whereby said heater circuit means is activated to cause said bimetal arm to create said communication of said at least one pressure source with interior chamber;
means discontinuing said heating by said heater circuit means upon achievement of a pressure level in said interior chamber in correspondence with said electrical signal, whereby said bimetal arm moves to sealingly engage said valve port.
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Accused Products
Abstract
A pressure transducer is disclosed which produces a variable fluid pressure level in correspondence with the level of a varying electrical signal. The particular application of the pressure transducer disclosed is for a vacuum modulator for producing a variable level vacuum pressure for operating an actuator utilized to position a blend air door in an automatic temperature control system for automotive passenger compartments. The pressure variation is accomplished by controlled communication of either a low pressure or a high pressure source with an interior chamber of the transducer housing, such controlled communication being produced by a pair of heated bimetal actuator devices, each including a bimetal arm which is normally biased to seal the respective inlet port associated with each of the low pressure and high pressure sources. One or the other of the bimetal arms is heated if the pressure level differs from the level corresponding to the electrical signal value by means of a bimetal heater circuit associated with each bimetal arm with the varying electrical signal to be transduced causing activation of the heater current in one or the other respective bimetal heater circuit depending on whether the pressure level is to be increased or decreased, until the pressure level reaches the corresponding level to that of the electrical signal. The electrical signal is disclosed as an error signal in an automatic control system which causes either a vacuum pressure or atmospheric vent port to be placed in communication with the interior chamber of the pressure transducer housing so as to either increase or decrease the vacuum pressure within the enclosure.
22 Citations
16 Claims
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1. A pressure transducer for producing a variable fluid pressure level from at least one pressure source corresponding to the level of a varying electrical signal input, the pressure transducer comprising:
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an enclosure having an interior chamber; means creating a controllable communication with said interior chamber including; a valve port and at least one heated bimetal actuator operatively associated with said valve port, said heated bimetal actuator including a bimetal arm biased into engagement with said valve port and including means sealingly engaging said bimetal arm and said valve port; heater circuit means for heating said bimetal arm causing said bimetal arm to deflect away from said valve port allowing communication of said at least one pressure source with said interior chamber of said enclosure; means activating said heater circuit whenever the pressure level in said interior chamber varies from correspondence with said varying electrical input signal in a direction tending to be corrected by communication of said at least one pressure source with said interior chamber; whereby said heater circuit means is activated to cause said bimetal arm to create said communication of said at least one pressure source with interior chamber; means discontinuing said heating by said heater circuit means upon achievement of a pressure level in said interior chamber in correspondence with said electrical signal, whereby said bimetal arm moves to sealingly engage said valve port. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
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14. An automatic temperature control system for producing a selected temperature in an enclosed space, said system comprising:
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temperature selector means for generated electrical signals corresponding to the selected temperature level; temperature sensor means for sensing the temperature level within said enclosed space and generating corresponding electrical signals; means for generating an error signal corresponding to the difference between said selector means signals and said temperature sensor signals; means for increasing or decreasing the temperature level in said enclosed space in response to generation of said error signal; said means including an actuator device having a movable output member which causes an increase or decrease in the temperature level of said enclosed space upon assuming a corresponding position; said means further includes means causing said movable member to assume a corresponding position in response to generation of said error signal; pressure transducer means producing a variable level fluid pressure including vacuum modulator means, said vacuum modulator means including means for providing intermittent communication of said vacuum modulator with a source of vacuum pressure and further including means for intermittently communicating said vacuum modulator valve with an atmospheric vent, and means controlling said intermittent communication of said vacuum source and vent source in correspondence with said signal to produce a modulated vacuum pressure corresponding to said error signal and wherein said pressure sensor means senses said modulated vacuum pressure; said vacuum modulator valve including a pair of heated bimetal arms and means for creating said intermittent communication of said vacuum source and said vent source corresponding to movement of a respective one of said bimetal arms and further including a heater circuit and mens producing a heating current in a respective heater circuit corresponding to said error signal in either sense of said sensed temperature difference; said actuator means being responsive to the level of pressure generated by said pressure transducer means to assume said corresponding position of said movable member; pressure sensor means generating electrical signals corresponding to said pressure level and means nulling said error signal upon movement of said output member into the corresponding position of said movable member to said error signal. - View Dependent Claims (15, 16)
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Specification