US2147699A - Engine cooling system - Google Patents

Description

Feb. 21, 1939. F. MA HARDIMAN ENGTNE COOLTNG SYSTEM Filed Jan 20. 1938 itl Patented Feb. 21, 1939 UNITED STATES YPmlazn'r OFFICE ENGINE COOLING SYSTEM Application January 20, 1938, Serial No. 185,828

4 claims. (ci. csi- 25) This invention relates to heat exchange systems and more particularly to an arrangement for the conservation oi' the heat exchanging medium. i

Conventional automobile radiators chord proper cooling of the engine for all usual driving conditions but there are times when overheating causes surging of the liquid from the engine jacket and loss of the coolant through the overflow or system breather vent. The surging tendency ls most likely to enist following a sudden stop from a hard run in weather adverse to cooling. The extremely hot engine cylinder lolocli calls for additional heat transfer and with the engine driven fan and pump out ci operation the body of liquid stands almost still in the engine jacket and continues to absorb heat nally going into steam.

The large expansion incident to the conversion ci liquid into steam forcibly pushes the liquid ahead and raises the level in the radiator. Additional boiling follows and in a succession of pulsations or spurts, liquid and steam are coughed out of the engine jaciret, a portion ci the liquid supply spilling through the overnow pipe. Sometimes halt or more of the system contents is discharged before after hoiling ceases and the loss is enpensive if the cooling solution includes a costly antiireeze, but in any event it is annoying to the car owner and if the loss occurs in a region re mote from a convenient source of repienisent liquid, further operation of the vehicle may ruin the engine.

lit has been proposed heretofore to provide the overflow pipe with a pressure valve to resist en pulsion oi the cooling liquid but this is only partly successful in stopping waste and furthermore the internal pressure developed may be so high as to strain the hose connections, water pump packings, gaskets and the radiator assembly, therehy increasing the likelihood oi leakage and damage. lt has also been proposed to provide an auxiliary or expansion tank outside the circulating system to receive and store expelled liquid for subsequent return to the system. The advantages of tooth of these previous expedients are combined accordirng to the present invention in that there has been provided beyond the circulating system and as apart of the overflow a supplemental reservoirv vented through a relatively low pressure relief valve and having a relatively large inlet for the flow from the engine jacket with minimum resistance to surging liquidand steam mixture. The arrangement is such. that the mixture enters above the floor of the storage reservoir so that there can be a ready separation of the liquid and steam, the heavy liquid dropping to the iloor so as not to block the inlet and the lighter vapors rising to the roof where the overflow valve is located so that the vapors are nrst to leave the system through the overiow while the liquid within the capacity oi the tank remains for return to the circulating system as the temperature oi the cylinder block drops ou.

To reduce pressure strains and enlarge the can ld pacity of the storage reservoir it is here proposed to provide the tank with expansible walls and according to one embodiment of the invention the reservoir located ahove the normal system liquid level, is rigidly mounted on and forms a unit with it the radiator assembly and for convenience the flexible end walls have coupled thereto the inlet and outlet headers of the radiator assembly through henihle conduits which accommodate relative movement oi the end walls. inasmuch as the outlet connection in this arrangement passes through the middle oi" the i'leitihle end wall it `carries a downturned extension which opens into the tank near the floor thereof for the withdrawal of liquid hy a siphoning action or more precisely hy reason oi an internal depression due to contraction of the system contents upon cooling. To prevent the action oi suction above the liquid level in the auxiliary tant: the inlet is provided with a check valve which opens freely into the .3o.

tanlr hut closes against hach how. 'This checlr valve can be omitted if the outlet connection is extended downwardly trom the door of the 'tunis ior gravity return oi the licitud.

lor a better understanding ci the invention reference may be made to the detail structure shown in the accompanying drawing wherein Figure l shows in perspective an engine cooling system having the invention applied thereto; Figure 2 is an enlarged view partly in section show- 4m ing the end wall construction and inlet connection to the storage tank; Figure 3 is a sectional view of the overflow controlling valve and Figure d shows a modification.

Referring to the drawing the reference numeral du i indicates an engine block at the front oi which is located the water pump 2 and radiator fan d both driven by the engine in the usual fashion for circulating water through the system and drawing air through the radiator. The suction side of the pump is connected by a hose 4 with the nottom portion of the outlet header or tank 5 extending along one side of the radiator core 6 which is of the cross flow type for purpose of illustration. The outlet from the engine jacket is coupled by the hose 1 to the inlet header or tank 8 on the opposite end oi the radiator core i. On the inlet header I is a filler spout i which terminates near the top oi' the radiator assembly and determines the maximum level to which the system may be illled. A removable closure cap I0 is provided to seal the filler spout.

Above the normal system level is the expansion or storage tank Il secured to the radiator assembly by means of the. holddown straps shown at l2. This tank is shown as being of cylindrical shape and near the top thereof is provided with an apertured raised boss I 3 to which is tted a cupped stamping Il enclosing a pressure valve for the overiiow or vent pipe I5. This valve includes a metal disk Il and a ilexible or rubber disk 16a bearing one against the other and seating on the raised boss Il under iniiuence of a light spring i1. The two disks i6 and lia are provided with offset ports or openings i8 and I9, respectively, which normally are closed from each other by reason of the face to face contact of the disks. Thus the system is closed to atmosphere unless internal pressure is sunlcient to overcome the spring Il to unseat the valve assembly or internal suction draws the flexible disk i611 inwardly to separate it from the rigid metal disk I6 and allow intercommunioation between porm i8 and I8.

The opposite ends of the tanks are provided with exible walls which may be in the nature of a bellows-like construction as shown in Figure 2 where 20 indicates a exible Wall having a central aperture to which is iltted a iexible disk 2| which is peripherally joined to a second flexible disk 22. Secured to the disk 22 in line with the central aperture therein is an elbow tting 23 for connection by a ilexible hose 24 with a pipe iltting on the top of the inlet tank 8. By reason of the flexible hose section 24 the relative movement of the end walls upon expansion or contraction may take place. Positioned over the central opening in the plate 22 is an inwardly opening Ilap valve 25 which allows free movement of huid from the hot side of the radiator into the expansion tank but closes against back pressure. The opposite end wall construction is much the same as that just described except that in this instance the cutlet pipe 26 connected by the flexible hose 21 to the cold side of the radiator core extends through the central portion of the end wall and has a downturned extension 2B opening near the bottom of the tank for the withdrawal of liquid therefrom.

In the normal operation of the system no liquid will be contained within the storage tank but the coolant will be drawn by the pump 2 from the bottom of the outlet header 5 and move through the engine jacket to absorb heat and pass out by the hose l and into the top of the inlet header 8 for return flow to the header 5 through the radiator core 6 giving up its heat to the air stream induced by fan operation and car movement. Should conditions be favorable to overheating, the formation of steam in the cylinder jacket displaces liquid therein, and the recurring action causes an intermittent gushing through the outlet to the hot side of the radiator core and with the increase in volume the liquid and steam mixture will rise in the inlet connection 23 and enter the expansion tank. The vomited liquid will drop to the floor out of the path oi' succeeding surges while the vapors will rise to the roof. 'I'he vapors will be held within the tank for condensation as they give up their heat unless the internal pressure exceeds the force ot the spring I1 in which case some of the vapors separated out will leave the system. To relieve the parts from pressure strains the iiexible end walls will move outwardly and enlarge the capacity of the tank and lessen the loss of the overflow. Under unusually severe conditions the Vexpansion tank may become completely filled with liquid and some of the-liquid may leave the system. However, for practical purposes the capacity of the expansion tank will be such that suflcient liquid is retained to enable subsequent operation of the engine without harm being done. As the engine ilnally cools down the liquid in the circulatory system will contract in volume as it gives up its heat and the suction produced will close the flap valve 25 and cause the liquid to be siphoned out of the tank through the outlet conduit 2B to restore the liquid level in the system.

As an alternative embodiment the expansion tank may be constructed as shown in Figure i as including a xed capacity section 3i) and an expansible bellows section 3l. In this case the xed section will be mounted to the radiator assembly by the strap 32 and will carry in its top portion the pressure valve casing 33 controlling the overflow pipe 34 and the connection to the system is through the standpipe 35 projecting upwardly from either of the headers, as for exam.- ple the outlet header 3B, through the bottom of the tank section 3U. This standpipe 35 is shown as extending to a point near the top of the tank and as having a bleed port or vopening 3l for the return flow of liquid from the bottom oi the tank. The return of the liquid will be by gravity and is a small enough stream as not to interfere with the free upward mr vement of liquid being forced through the standpipe 'oy internal pressure surges. In this case the expansible section 3l will increase the size of the tank in accordance with overflow demands and relieve the parts from pressure strains.

I claim:

1. In a heat exchange system, a radiator having inlet and outlet tanks, an expansible storage tank mounted on the radiator above the normal system liquid level and having flexible end walls, a flexible inlet connection between the inlet tank and the storage tank through one of said flexible end walls, an inwardly opening check valve controlling ilow through said connection, a exible outlet connection between the opposite end wall of the storage tank and said outlet tank, said last mentioned connection having a siphoning extension opening near the floor of the storage tank, and overflow vent means near vthe roof of the storage tank having an outwardly opening pressure relief valve and an inwardly opening vacuum relief valve.

2. In a heat exchange system, a radiator having inlet and outlet tanks, an expansible storage tank mounted on the radiator above the normal system liquid level and having flexible end walls, a flexible in et connection between the inlet tank and the stoi age tank through one of said ilexible end Walls, an inwardly opening Check valve controlling ilow through said connection, a flexible outlet connection between the opposite end wall of the storage tank and said outlet tank. said last mentioned connection having a siphoning extension opening near the floor of the storage tank.

3. In a heat exchange system, a radiator having a pair of headers, an expansion tank mounted on the radiator, and having expansible end walls,

and exibie conduits carried by said end walls and communicating said tank with the pair of headers.

4. In an engine cooling system, a radiator assembly including a pair of headers anda core, an expansion tank xedly mounted on the radiator assembly above the normal liquid level of the system, expansible bellows constituting opposite end walls of the tank, and flexible conduits secured to said end walls for communicating the opposite ends of said tank with said pair of radiator headers.

- Y FRANK M. HARDIMAN.

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