Electric engine coolant heater

Claim 2

A heater for warming liquid coolant in a cooling system of an engine and for forcing said coolant through the cooling system without creating any appreciable convection current in said heater, said heater comprisIng: a. an enclosed reservoir for containing liquid coolant, said reservoir having a fluid inlet and a fluid outlet to permit said reservoir to be connected in said cooling system with said coolant substantially filling said reservoir; b. a one-way inlet valve in communication with said fluid inlet to permit coolant to flow into said reservoir and to prevent coolant from leaving said reservoir through said fluid inlet; c. a one-way outlet valve in communication with said fluid outlet to permit heated coolant to leave said reservoir and to prevent coolant from entering said reservoir through said fluid outlet; d. an electrical heating element coupled to said reservoir for heating said coolant; and e. a thermostat having an upper limit and a lower limit, said thermostat being electrically connected to said heating element to control the supply of electricity to said heating element, said thermostat being positioned so that it is in thermal contact with the contents of said reservoir and is responsive to the temperature of said coolant in said reservoir in both its liquid and vapor states, the supply of electricity to said heating element being interrupted when the temperature sensed by the thermostat reaches said upper limit, and being resumed when said temperature falls to said lower limit, said upper limit being such that at least a portion of the liquid coolant in said reservoir is vaporized when said heating element is energized and heated coolant is expelled through said outlet, the heating element being disconnected from its supply of electricity by said thermostat when said upper limit has been reached, whereupon the temperature in said reservoir falls so that the vapor pressure in said reservoir drops substantially thereby drawing a fresh charge of liquid coolant into said reservoir through said fluid inlet.

Claim 3

A heater as claimed in claim 1 wherein said fluid inlet and said fluid outlet are substantially in alignment and said heating element is in said reservoir.

Claim 4

A heater as claimed in claim 2 wherein said inlet valve comprises a first disclike member positioned at the inner end of said fluid inlet against an end wall of said reservoir, said first disclike member being pivotally mounted and the inner end of said fluid inlet being shaped to provide a seat for said first disclike member when said first disclike member is pressed against said fluid inlet inner end.

Claim 5

A heater as claimed in claim 3 wherein said outlet valve comprises a second disclike member positioned at the inner end of said fluid outlet against an opposite end wall of said reservoir, said second disclike member being pivotally mounted, and a washer secured to said opposite end wall and positioned inwardly of said second disclike member to provide a seat for the same.

Claim 6

A heater as claimed in claim 2 wherein a portion of said heating element is adjacent to an inner surface of a wall of said reservoir, and said thermostat is in contact with an outer surface of said wall opposite said portion of said heating element, said wall being thermally conductive.

Claim 7

In combination with an engine cooling system containing liquid coolant, a heater for warming the liquid coolant and for forcing said coolant through the cooling system, the heater being positioned at about the upper level of coolant in the system so that the heater is substantially full of coolant; the heater comprising an enclosed reservoir for containing liquid coolant, said reservoir having a fluid inlet and a fluid outlet to permit said reservoir to be connected in said cooling system with said coolant substantially filling said reservoir; a one-way inlet valve in communication with said fluid inlet to permit coolant to flow into said reservoir and to prevent coolant from leaving said reservoir through said fluid inlet; a one-way outlet valve in communication with said fluid outlet to permit heated coolant to leave said reservoir and to prevent coolant from entering said reservoir through said fluid outlEt; an electrical heating element coupled to said reservoir for heating said coolant; and a thermostat having an upper limit and a lower limit, said thermostat being electrically connected to said heating element to control the supply of electricity to said heating element, said thermostat being positioned so that it is in thermal contact with the contents of said reservoir and is responsive to the temperature of said coolant in said reservoir in both its liquid and vapor states, the supply of electricity to said heating element being interrupted when the temperature sensed by the thermostat reaches said upper limit, and being resumed when said temperature falls to said lower limit, said upper limit being such that at least a portion of the liquid coolant in said reservoir is vaporized when said heating element is energized and heated coolant is expelled through said outlet, the heating element being disconnected from its supply of electricity by said thermostat when said upper limit has been reached whereupon the temperature in said reservoir falls so that the vapor pressure in said reservoir drops substantially thereby drawing a fresh charge of liquid coolant into said reservoir through said fluid inlet.

Claim 8

In combination with an engine cooling system containing liquid coolant, a heater for warming the liquid coolant and for forcing said coolant through the cooling system, the heater being positioned at about the upper level of coolant in the system so that the heater is substantially full of coolant; the heater comprising an enclosed reservoir for containing liquid coolant, said reservoir having a fluid inlet and a fluid outlet to permit said reservoir to be connected in said cooling system with said coolant substantially filling said reservoir; a one-way inlet valve in communication with said fluid inlet to permit coolant to flow into said reservoir and to prevent coolant from leaving said reservoir through said fluid inlet; a one-way outlet valve in communication with said fluid outlet to permit heated coolant to leave said reservoir and to prevent coolant from entering said reservoir through said fluid outlEt; an electrical heating element coupled to said reservoir for heating said coolant; and a thermostat having an upper limit and a lower limit, said thermostat being electrically connected to said heating element to control the supply of electricity to said heating element, said thermostat being positioned so that it is in thermal contact with the contents of said reservoir and is responsive to the temperature of said coolant in said reservoir in both its liquid and vapor states, the supply of electricity to said heating element being interrupted when the temperature sensed by the thermostat reaches said upper limit, and being resumed when said temperature falls to said lower limit, said upper limit being such that at least a portion of the liquid coolant in said reservoir is vaporized when said heating element is energized and heated coolant is expelled through said outlet, the heating element being disconnected from its supply of electricity by said thermostat when said upper limit has been reached whereupon the temperature in said reservoir falls so that the vapor pressure in said reservoir drops substantially thereby drawing a fresh charge of liquid coolant into said reservoir through said fluid inlet.

Claim 9

Apparatus as claimed in claim 6 wherein said fluid inlet and said fluid outlet are substantially in alignment.