I|l|||IlllllllIllllllllllllllllllllllllllllllllllllllllllllllllllllll?llll _ USO05255635A Umted States Patent [19] [11] Patent Number: 5,255,635 Schiifer et al. [45] Date of Patent: Oct. 26, 1993

[54] EVAPORATIVE COOLING SYSTEM FOR AN [56] References Cited INTERNAL COMBUSTION ENGINE Us PATENT DOCUMENTS HAVING A COOLANT EQUALIZING TANK 4,648,356 3/1987 Hayashi ...... 1. 123/412]

Inventors: Hms-Jiirgen sch-?fe", Braunschweig; Ct ...... Herbert schipert?ns’ Gifhom; Bodo 5,176,112 1/1993 Sausner 61 a1...... 123/4121 Scheibner, Wolfsburg, all Of Fed. FOREIGN PATENT DOCUMENTS Rep. of Germany 3339717 1/1990 Fed. Rep. of Germany . [73] Assign“: Volkswagen AG, wolfsburg, Fed‘ 1252221 12/1960 France ...... 123/4115 mm of Germany Primary Examiner-Noah P. Kamen Attorney, Agent, or Firm-Brumhaugh, Graves, [21] App]. No.: 803,348 Donohue & Raymond _ [22] Filed: Dec. 4, 1991 [57] ABSTRACT _ _ _ _ _ An evaporative cooling system for an internal combus 1301 Fm'e‘g" Apphcaho“ Pnomy Data tion engine has an equalizing tank which is sealed from Dec. 17, 1990 [DE] Fed. Rep. of Germany ...... 4040324 the atmosphere and divided by a yielding Wall into an ~ 1 air-equalizing chamber and a coolant chamber and [51] Int. Cl.5 ...... F01? 9/02 which has a low ?ow-resistance connection to the suc [52] U.S. Cl...... 123/412; 123/415 tion side of a condensate pump. [58] Field of Search ...... 123/412, 41.21, 41.5, l23/41.15 3 Claims, 1 Drawing Sheet

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' I 10 ( \ 1 ) 11 11. e “ 12 . US. Patent Oct. 26, 1993 5,255,635 5,255,635 1 2 ant is vaporized by engine heat. The coolant vapor EVAPORATIVE COOLING SYSTEM FOR AN generated in the cooling chambers 2 passes from the INTERNAL COMBUSTION ENGINE HAVING A engine through a vapor line 3 into a condenser 4 from COOLANT EQUALIZING TANK which condensed coolant is supplied to a condensate 5 line 5. The condenser 4 also serves as a cooler for any BACKGROUND OF THE INVENTION liquid coolant received through the line 3. A coolant This invention relates to evaporative cooling systems supply tank 6 is connected to the condensate line 5. It for internal combustion engines which include a coolant will be understood that a conventional thermostat-con equalizing tank. trolled condenser bypass line (not shown) may be ar Evaporative cooling systems having coolant equaliz ranged to bypass coolant around the condenser 4 when ing tanks are disclosed, for example, in German Offen the engine is warming up so that the engine will reach legungsschrift No. 33 39 717 and U.S. Pat. No. its normal operating temperature relatively quickly. 4,648,356. In those systems, an air chamber in the equal A condensate pump 7, driven either directly from the izing tank is open to the atmosphere, and the coolant engine or by an electric motor, is provided in the con chamber of the equalizing tank, which is separated from densate line 5. If the pump is driven by an electric mo the air chamber by a yielding wall, serves to receive air tor, it can operate independently of the speed of the and/or coolant vapor from the coolant system. engine 1. The pump transfers comparatively cool liquid coolant through the condensate line 5 to the cooling SUMMARY OF THE INVENTION chambers 2 of the engine, depending upon eh vaporiza Accordingly, it is an object of the present invention 20 tion of coolant in the engine and therefore upon the to provide an evaporative cooling system with an equal engine load. In the illustrated embodiment, the coolant izing tank which overcomes the disadvantagesof the passes through a vehicle heating system 8 between the prior art. pump 7 and the engine. Another object of the invention is to provide an evap Because the volume of coolant vapor in the cooling orative cooling system of this type which is arranged to 25 system is subject to large ?uctuations, a coolant equaliz accommodate dynamic variations in the volume of ing tank 9, connected to the condensate line 5, is parti coolant vapor resulting from variations in engine load tioned by a membrane 10 into an air chamber 11 and a rapidly. coolant chamber 12. In the illustrated embodiment, an These and other objects of the invention are attained additional air chamber 13 is connected to the air cham by providing an evaporative cooling system having a ' 30 ber 11, which may also contain a mechanical spring 15. condensate pump in a condensate line leading from a In order to enable the condensate pump 7 to respond condenser to the engine and an equalizing tank which quickly to changes in the coolant requirements of the has a yielding wall between air and coolant chambers engine 1, the coolant chamber 12 is connected by a line and which has a low flowresistance communication 14 having a large ?ow cross-section, and hence low with the suction side of the condensate pump in which flow resistance, to the suction side of the coolant pump the air chamber is sealed from the atmosphere. 7 following the shortest possible route. Because the air Because the connection between the coolant chamber chambers 11 and 13 of the equalizing tank ‘9 are sealed of the equalizing tank and the suction side of the con for the atmosphere, the condensate pump 7 can vary its densate pump has a low flow resistance, the pump is able to deliver rapidly the quantity of liquid coolant delivery as a function of the then load on the engine 1 at required from time to time, depending upon variations any ambient atmospheric pressure. in engine load, to the cooling chambers of the internal With this arrangement, the invention provides a sim combustion engine with no great expenditure of energy. ple construction for accommodating dynamic varia At the same time, the supply of coolant is unaffected by tions in the volume of coolant vapor resulting from the ambient atmospheric pressure, which may vary variations in the load on the internal combustion engine depending on whether the internal combustion engine is 45 being cooled. operating at high or low altitude, because the air vol Although the invention has been described herein ume in the rigid housing of the equalizing tank is sealed with reference to a speci?c embodiment, many modifi from the atmosphere. cations and variations therein will readily occur to The yielding wall in the equalizing tank may consist those skilled in the art. Accordingly, all such variations of a piston or the tank may alternatively contain a con and modifications are included within the intended ventional elastic membrane. If an elastic ‘membrane is scope of the invention. used, it is expedient to bias the membrane toward the ' We claim: coolant chamber with a compression spring disposed in 1. An evaporative cooling system for an internal the air chamber. combustion engine comprising an engine, a condenser 55 for vaporized coolant, a condensate line to supply cool BRIEF DESCRIPTION OF THE DRAWING ant from the condenser to the engine, a condensate Further objects and advantages of the invention will pump int eh condensate line, and a rigid coolant equaliz be apparent from a reading of the following description ing tank divided by a yielding wall into a coolant cham in conjunction with the accompanying drawing which ber and an air chamber, wherein the equalizing tank is is a perspective schematic diagram, partly in section, connected to the suction side of the condensate pump showing a representative embodiment of an evaporative and the air chamber is sealed from the atmosphere. cooling system arranged according to the invention. 2. An evaporative cooling system according to claim 1 including a mechanical spring in the air chamber act DESCRIPTION OF PREFERRED EMBODIMENT ing upon the yielding wall. In the typical embodiment of the invention shown in 65 3. An evaporative cooling system according to claim the drawing, a reciprocating-piston internal combustion 1 wherein the yielding wall includes an elastic mem engine 1 of conventional design has a plurality of cool brane. ing chambers or passages 2 in which a circulated cool Q t t t t