Method and apparatus for purging air from internal combustion engine cooling systems

Claim 1

In a method of operating a closed cooling liquid circuit for an internal combustion engine, which circuit includes a circulation pump, which method includes independently of said pump creating a fluid pressure sufficiently high to prevent the formation of steam within said cooling circuit, under conditions where the temperature of the liquid in the cooling circuit ranges between values above and values below the boiling point of the liquid at atmospheric pressure, applying said fluid pressure to the liquid in said cooling circuit, and thereafter continuously maintaining said fluid pressure on said liquid in the cooling circuit independently of the operating temperature thereof and independently of the speed of the engine from and including zero upwardly to a maximum value, the improvements in said method whereby an intermittently operated internal combustion engine which normally contains air and a thermally expandable coolant liquid in said cooling circuit is cooled with improved reliability and efficiency, which improvements comprise in combination the steps of: a. substantially completely purging air from said cooling circuit by i. expelling air and excess coolant liquid from said cooling circuit as said engine heats to operating temperature and said coolant liquid expands; ii. separating said expelled air from said excess coolant liquid; iii. introducing into said cooling circuit as said coolant liquid cools from operating temperature and contracts a volume of coolant liquid equal to said excess coolant liquid and said expelled air; iv. repeating steps (i), (ii), and (iii) until substantially all air has been expelled from said cooling circuit and said cooling circuit is substantially completely filled with said thermally expandable coolant liquid; b. creating an effective fluid pressure sufficient to substantially prevent boiling of the cooling liquid within said cooling circuit by thermally expanding said liquid at a temperature below its normal boiling point in said cooling circuit; c. withdrawing coolant liquid from said cooling circuit when the pressure therewithin exceeds said effective pressure; d. introducing makeup coolant liquid into said cooling circuit when the pressure therein decreases from said effective pressure to a lower pressure.