US 3238932 A
Description (OCR text may contain errors)
March 8, 1966 N B. H. SIMPSON 3,238,932
SEALED COOLING SYSTEM FOR AN INTERNAL COMBUSTION ENGINE Filed March 30, 1964 BRUCE bfJ/MPJO/V INVENTOR A R/VE'YS United States Patent Office 3,238,932 Patented Mar. 8, 1966 3,238,932 SEALED COOLING SYSTEM FOR AN INTERNAL COMBUSTIQN ENGINE Bruce H. Simpson, Deal-born, Mich., assignor to Ford Motor Company, Dearborn, Micl1., a corporation of Delaware Filed Mar. 30, 1964, Ser. No. 355,727 2 Claims. (Cl. 123-415) This invention relates to a sealed cooling system for an internal combustion engine and more particularly to the sealed cooling system that embodies a novel manner of precluding air contact with the coolant.
The emphasis upon reduced maintenance motor vehicles has created a demand for sealed engine cooling systems. In liquid cooled internal combustion engines, the coolant of a sealed system should contain sufficient inhibitors to preclude the formation of rust. The coolant also should have a low freezing point to meet all climatic conditions. It is additionally desirable to provide a coolant having a high boiling point to permit higher engine operating temperatures and to reduce the possibility of coolant losses through boiling.
Although long-life coolants have been proposed that retain their rust inhibiting and low freezing point characteristics, these coolan-ts can deteriorate within the normal vehicle life. One major cause of coolant deterioration is the chemical action that results from the contact of the coolant at high engine operating temperatures with air. It is desirable, therefore, to purge the cooling system of air to extend the life of the coolant.
The volume of the liquid coolant varies greatly between the lowest anticipated ambient temperature and the normal engine operating temperature. Some form of expansion device must be provided to accommodate these variations in coolant volume. In the conventional downflow radiator, the upper header tank serves as an expansion device. In a cross flow radiator, a separate expansion tank must be employed.
The header tank of a downflow radiator or the expansion tank of a cross flow radiator have sufficient air space to permit coolant expansion. The liquid turbulence within the expansion device, however, causes the air to enter the cooling system. Thus, even though the system may have been originally purged of air, air will soon enter the system and cause deterioration of the coolant.
It, therefore, is the principle object of this invention to provide a sealed cooling system that precludes the contact of air with the liquid coolant.
A sealed liquid cooling system for an internal combustion engine embodying this invention comprises a cooling jacket for the engine. A heat exchanger is provided to dissipate the heat generated by the engine. Means are provided for circulating liquid coolant between the heat exchanger and the engine cooling jacket. An expansion device is provided to accommodate temperature induced variations in the volume of the liquid coolant. The expansion device comprises a substantially rigid container having an impervious flexible wall. The flexible wall is in contact with the liquid coolant at the minimum expected coolant volume within the system and is decformable by the coolant upon temperature induced increases in coolant volume.
Further objects and advantages of this invention will become more apparent when considered in conjunction with the accompanying drawings, wherein:
FIGURE 1 is a schematic view of an internal combustion engine and its cooling system showing a first embodiment of the invention.
FIGURE 2 is a partial cross sectional view of a radiator for an internal combustion engine showing another embodiment of the invention.
Referring now in detail to the drawings and in particular to FIGURE 1, a liquid cooled internal combustion engine is identified generally by the reference numeral 11. The engine 11 includes a cylinder block -12 and a cylinder head 13 that are provided with cooling jackets through which a suitable liquid coolant may be circulated. A crankshaft driven coolant pump 14 is positioned at the front of the cylinder block 12 for circulating the liquid coolant.
A cross-flow radiator or heat exchanger, indicated generally by the reference numeral 15, is positioned at the front of the engine 11. The radiator 15 has a central section 16 made up of a plurality of coolant flow tubes and heat exchanging fins. Header tanks 17 and 18 are positioned at each end of the section =16 in open communication with the tubes. An engine driven fan 19 causes air circulation across the radiator central section 16 to dissipate the heat generated by engine operation.
A coolant outlet fitting 2 1 is positioned at the front of the cylinder head 13. A coolant inlet fitting 22 is positioned at the upper end of the header tank 17. A flexible hose 23 is connected at opposite ends to the fittings 2'1 and 22 as by the clamps 24 and 25 for coolant flow from the engine cooling jacket to the radiator 15. A coolant outlet fitting 26 is positioned at the bottom of the header tank 18. A flexible hose 27 interconnects the outlet fitting 26 with the inlet side of the coolant pump 14.
The coolant within the engine 11, hoses 23 and 27, and the radiator 15 is purged of air when the system is initially filled. The aforementioned elements are filled completely with coolant at a normal ambient temperature. The coolant will expand at engine operating temperatures however. An expansion device, indicated generally by the reference numeral 28, is provided to accommodate the variations in volume of the engine coolant. The expansion device 28 is the highest point in the system and comprises a substantially rigid tank 29 having a coolant fitting 31. A flexible hose 3-2 is connected at one end to the fitting 31 by a clamp 33. The other end of the hose 3-2 is connected to a coolant fitting 34 positioned at the upper end of the header tank 17 by a clamp 35.
A flexible wall 36 extends across the tank 29 on one side of the fitting 31. The cooling system is charged with sufficient coolant so that the coolant will contact the flexible wall 36 in an unexpanded state, as denoted by the line 3611, at the lowest anticipated ambient temperature. As the coolant within the system becomes heated by engine operation or with increases in ambient temperature, the coolant will expand and cause the flexible Wall 36 to deform. It should be readily apparent that at all engine temperatures the impervious flexible well 36 will preclude entry of air into the cooling system although expansions in coolant volume are accommodated.
The internal volume of the tank 29 is chosen to limit the deformation of the flexible wall 36 as shown by the broken line 36b in the drawing. It is desirable to pressurize the cooling system to increase the boiling point of the coolant. This may be done by selecting a proper internal volume of the tank 29 to achieve the desired pressurization.
A pressure relief valve, indicated generally by the reference numeral 37 may be provided in the tank 29 on the coolant side of the flexible wall 36. The pressure relief valve may be threaded onto a fitting 38 in the tank 29 to permit removal and charging of the system. The pressure relief valve 37 includes a movable valve member 39 that is biased by a coil spring 41 to a closed position. The spring tension is chosen so that the valve member 39 will be unseated when the coolant pressure exceeds a predetermined value. During most normal stages of engine operation the valve member 39 will be closed.
The previously described embodiment employed a cross flow radiator and required a separate expansion device. If a downflow radiator is provided, it is possible to combine the expansion device with the upper radiator header tank. Such an embodiment is shown in FIGURE 2. The engine and the lower portion of the radiator have not been shown since these features are conventional. It is to be understood that the engine and its coolant inlet and outlets may be the same as shown in FIGURE 1. The engine coolant inlet may be connected to the lower header tank of the radiator by a flexible hose as is well known.
Referring now specifically to FIGURE 2 a downflow radiator is indicated generally by the reference numeral 51. The radiator 51 includes a plurality of flow tubes 52 surrounded by heat exchanging fins 53. An upper header tank 54 is secured to the radiator in open communication at its lower side with the flow tubes 52. A coolant inlet fitting 55 of the radiator 51 receives liquid coolant through a flexible hose 56 that is in communication with the engine (not shown). A clamp 57 provides a liquid tight seal between the hose 56 and the inlet fitting 55.
A flexible, impervious wall 58 extends across the header tank 54. As in the previously described embodiment, the liquid in the radiator 51, the engine and the coolant hoses has been purged of air when the system was initially filled. The flexible wall 58 is in contact with the coolant completely across the header tank 54 at the lowest anticipated ambient temperature. The inlet fitting S lies below the wall 58 at this temperature.
As the engine coolant temperature rises, the increase in volume of the coolant deforms the flexible wall 58. The internal volume of the header tank 54 is sufficient to accommodate the increase in volume at the engine normal operating temperature. In this condition the flexible wall 58 is deformed into contact with the upper surface of the header tank 54 as denoted by dotted lines in FIGURE 2. If desired the system may be pressurized through a reduction in the volume of the header tank 54.
Means are provided to permit charging of the coolant in the system and to provide for pressure relief. These means comprise a fitting 59 that extends from above the upper surface of the header tank 54 into the header tank below the flexible wall 58. A combined filler cap and pressure relief valve 61, which may be of the type shown in FIGURE 1, is positioned at the inlet of the fitting 59.
It is to be understood that various changes and modifications may be made without departing from the spirit and scope of the invention, as defined by the appended claims.
1. A sealed liquid cooling system for an internal combustion engine comprising a cooling jacket for said engine, a heat exchanger, said heat exchanger comprising a plurality of coolant flow passages interconnected by at least one header tank, means for circulating liquid coolant between said heat exchanger and said cooling jacket, the liquid coolant contained in said cooling jacket, said coolant flow passages and said last-named means being substantially purged of air, and a flexible wall extending across said header tank, said flexible wall being in contact with the liquid coolant at the minimum expected coolant volume within said system and being impervious for precluding entry of air into said system, said flexible wall being deformable upon temperature induced increases in the coolant volume.
2. A sealed liquid cooling system as defined by claim 1 wherein the internal volume of the header tank is equal to no more than the increase in volume of the liquid coolant experienced by heating the coolant from the lowest anticipated ambient temperature to normal cooling system operating temperatures.
References Cited by the Examiner UNITED STATES PATENTS 2,147,699 2/1939 Hardiman --34 3,076,479 2/1963 Ottung 12341.5 X
3,168,080 2/1965 Latterner 123-4126 FOREIGN PATENTS 964,429 7/1964 Great Britain.
KARL J. ALBRECHT Primary Examiner.
MARK NEWMAN, Examiner.