Therm-O-Disc, Incorporated

Ronald L Holden

Donald E Place

Douglas P Versaw

Gordon K Wells

A thermally responsive pressure relief valve using a bimetallic valve disc as a component. The bimetallic valve disc is used as a temperature sensitive valve seal. When temperatures go beyond the set point of the disc, it opens the valve with a snap acting motion permitting pressure to be vented through the valve. The valve disc automatically resets and reseals the valve when temperatures return to the reset point of the disc.

Thermally responsive relief valve

An electric switch, particularly a thermostatic switch, includes a pair of switches having contacts connected to three terminal members having connector terminals aligned along a common axis. The connector terminals include a pair of outside connector terminals and a central connector terminal. One switch has a fixed contact connected with one of the pair of outside connector terminals and a movable contact connected with the central connector terminal. The other switch has a movable contact connected with the other outside terminal and a fixed contact connected with the central connector terminal.

Electric switch and contact terminal arrangement

An electric switch, particularly a thermostatic switch, includes contacts connected to at least three terminal members having connector terminals aligned along a common axis.

Thermostatic electric switch

A heat collector for thermostatic fire detectors comprises a one-piece circular metal member having a closed central depression that forms the bottom of a bimetal snap disc chamber in a thermostatic switch.

Heat collector

A motor overload protector or the like is disclosed in which a switch chamber is defined by a cup-shaped element and a header adhesively secured to the open mouth of the cup. A plurality of parallel support pins extend through and are adhered to the header to form a tight seal therewith. A flat continuous shoulder is provided within the housing which sharply intersects with the inner walls of the housing. One face of the header engages the shoulder and the edges of the header snugly engage a portion of the walls of the housing between the shoulder and the open mouth to form the switch chamber with the support pins extending into the chamber. A suitable plastic, such as epoxy resin, is provided in the space between the header and the open mouth to provide a tightly sealed switch chamber. A bimetal snap assembly is cantilever mounted by welding adjacent one of the support elements in the chamber and has a movable contact mounted on its free end. A fixed contact is welded to another one of the plurality of support pins so that the bimetal assembly operating in response to predetermined bimetal temperatures moves the movable contact into and out of contact with the fixed contact. In another embodiment of the invention, a resistance heater is associated with the bimetal snap element to increase current sensitivity.

Sealed motor protector

A motor overload protector or the like is disclosed in which a bimetal snap disc is centrally supported by a stud which is press fitted into a bore within the body. The stud is knurled to provide axially extending teeth having a root diameter at least substantially equal to the diameter of the body stud receiving bore prior to the insertion of the stud so that sufficient friction is provided to maintain the stud in the calibrated position. Additional locking is provided where necessary by forming the stud with annular ribs which interlock with a potting material applied after assembly of the stud within the body. The device is calibrated by maintaining the disc at the desired operating temperature as the stud is pressed into the body stud receiving bore until the disc operates.

Calibration and mounting structure for motor controllers or the like

A hermetically sealed motor protector or the like is disclosed in which a switch chamber is defined by a cylindrical, cup shaped element and a header welded to one end thereof. A pair of insulated pins extend through the header substantially parallel to each other and on opposite sides of the center axis of the device. A switch including a stationary contact mounted on one pin and a movable contact assembly supported by the other pin is arranged so that the line of action of the movable contact is along a diametrical plane inclined with respect to the pins. Such structure facilitates the assembly of the device. The structure is arranged so that the pins supporting the bimetal snap element limits movement of the free end thereof in a direction away from the fixed contact to reduce the tendency for calibration drift and fatigue cracking of the snap element. In one embodiment, a shunt formed of flexible material is connected in parallel to the bimetal snap element to provide greater current carrying capacity. In another embodiment, a resistance heater is connected in series with the bimetal snap element to increase current sensitivity. The offset structure allows the use of a straight resistance heater, positioned closely adjacent to the center line of the snap element for good heat transfer. The heater mounting is arranged to accommodate thermal expansion and contraction without altering the calibration of the device.

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Mansfield, OH, United States of America

Ronald L Holden