Plug having encapsulated thermal sensor, for engine block heater

A thermal sensor construction comprising, in combination:

• (a) an electrical fitting,
• (b) a line cord constituted of plastics substance, said line cord having at least one electrical conductor embedded in it,
• (c) a plug fitting on said line cord, formed integral therewith, said plug fitting being cooperable with said electrical fitting,
• (d) a thermal sensor unit having electrical lead means connected with said electrical conductor,
• (e) means encapsulating said sensor unit,
• (f) said encapsulated sensor unit being imbedded in said plug fitting,
• (g) a portion of said encapsulating means projecting from and being exposed at the exterior of said plug fitting,
• (h) said plug fitting being attached to said electrical fitting and the exposed portion of said encapsulating means contacting said electrical fitting and receiving heat from said electrical fitting.

A plug for connection to terminals of an engine block heater of the type having electrical connector pins surrounded by a skirt carried by the heater, said skirt having a side wall, said plug comprising in combination:

• (a) a molded plug body constituted of resilient rubber-like material;
• (b) said plug body being telescopically receivable in the skirt of the heater, and having sockets adapted to mate with and receive the connector pins respectively of the heater when the plug is installed thereon,
• (c) said plug body having a thermal sensor unit comprising a thermally conductive casing, a portion of which is imbedded in the side of the plug body and retained thereby, and another portion of which is exposed and which protrudes above the surrounding surface of the plug body,
• (d) the resilience of the plug body being adapted to bias the conductive casing into firm engagement with the inner surface of the side wall of the skirt of the heater when the plug body is installed therein, thereby establishing good thermal contact between said side eall and said casing.

A plug for connection to terminals of an engine block heater of the type having electrical connector pins surrounded by a skirt carried by the heater, said skirt having a side wall, said plug comprising in combination:

• (a) a molded plug body constituted of resilient rubber-like material,
• (b) said plug being adapted to be telescopically received in the skirt of the heater, and having sockets adapted to mate with and receive the connector pins respectively of the heater when the plug body is installed thereon,
• (c) said plug body having a thermal sensor unit comprising a thermally conductive casing, a portion of which is imbedded in the side of the plug body and retained thereby, and another portion of which is exposed and which protrudes above the surrounding surface of the plug body,
• (d) said imbedded casing being retractable into the plug body, within limits, as a consequence of force applied to the casing when the plug is installed on said heater, said force being applied by the inner wall surface of the side wall of the skirt of the heater and being counteracted by corresponding transaxial forces applied by the connector pins of the heater on the sockets carried by the plug body when the latter is installed.

An electrical line plug for connection to a heater assembly having electrical terminals, said plug comprising in combination:

• (a) a molded plug body constituted of electrically insulating material,
• (b) receptacles on said body adapted to mate with the terminals respectively, of the heater assembly,
• (c) a circuit board carried in said plug body and having at least a portion thereof completely imbedded therein,
• (d) an electrical component mounted on said circuit board, and
• (e) a cover secured to said circuit board, said cover with said board completely enclosing said electrical component so as to isolate the latter from molten substance and prevent such substance from contacting the said component during molding of the plug body.

An electrical line plug for connection to a heater assembly having electrical terminals, said plug comprising in combination:

• (a) a molded plug body constituted of electrically insulating material,
• (b) receptacles on said body adapted to mate with the terminals respectively, of the heater assembly,
• (c) an electrical component carried in said plug body, and means in said body for making electrical connections thereto,
• (d) an electrically conductive cover having one portion imbedded in said plug body, and having another portion projecting above the surface of said plug body, and
• (e) spacer means on the plug body for retaining the cover in fixed position adjacent to but electrically insulated from said electrical oomponent, so as to electrically isolate the cover from the component and thereby eliminate the possibility of shock hazzard to personnel handling the plug and coming in contact with the said cover.