Hermetically sealed, relatively low pressure cooling system for internal combustion engines and method therefor

A hermetically sealed, relatively low pressure cooling system for internal combustion engines including a thermostat which opens at a predetermined engine operating temperature, comprising:

• a hermetically sealed radiator having a filling neck located in the top portion of the radiator, a nonpressurized cap in sealed relationship with said filling neck;
• a small expansion reservoir for liquid coolant integral with and connected in hermetically sealed relationship with the top portion of the radiator forming a composite structure thereby, said reservoir having coolant inlet means which projects downwardly into the radiator so that coolant will reside in the lower portion of the expansion chamber when said radiator is filled with coolant and having a closed dead air space in the upper portion of the expansion reservoir wherein liquid coolant due to engine heating during operation expands and flows freely from the radiator upwardly and into said expansion reservoir causing a relatively low pressure to be built up in the dead air space behind the coolant and subsequently returning from the reservoir into the radiator under the influence of the relatively low pressure in the closed dead air space to maintain the cooling system full at a full level at all times, whereby pressure in the hermetically sealed cooling system is maintained at a relatively low value compared to conventional high pressure systems which operate at or near 15 psi, said low pressure causing the boiling point of the coolant to remain at a relatively low value, permitting said thermostat of the engine to thereby control engine temperature over substantially the full range of engine operation and thus causing said engine to operate at a temperature at or in relatively close proximity to said predetermined temperature of the thermostat.

A method of operating an internal combustion engine at a temperature corresponding to the opening and closing temperature of the thermostat installed in the cooling system of the engine, comprising the steps of:

• confining liquid coolant within a hermetically sealed cooling system including a composite structure comprising a radiator and an integrally formed expansion reservoir located on a top portion of the radiator at or above the full level of coolant in the radiator and coupled to the radiator by coolant inlet means in the lower portion of the reservoir,
• filling the radiator to the full coolant level,
• allowing the coolant to expand and flow freely upwardly from the full coolant level of the radiator into the lower portion of the coolant expansion reservoir during engine operation, said reservoir further including a closed dead air space above the lower portion of the reservoir filled with coolant causing a relatively low pressure to be built up in the closed dead air space behind the coolant, and
• effecting automatic return of the expanded coolant in said reservoir to the radiator under the influence of said relatively low pressure in the dead air space of said reservoir behind said coolant,
• whereby pressure in the hermetically sealed coolant system is maintained at a relatively low level compared to conventional high pressure systems which operate at or near 15 psi, said low level being determined by the pressure behind the coolant in the closed dead air space of the reservoir, said relatively low pressure causing the boiling point and temperature of the coolant to remain at a relatively low level thereby permitting the thermostat to control the engine temperature over substantially the full operating range of the engine, and thus causing said engine to operate at or in relatively close proximity to said predetermined temperature of the thermostat.