US3752132A

US3752132A - Dual cooling system for engines

Info

Publication number: US3752132A
Application number: US00135497A
Authority: US
Inventors: E Bentz; R Hiserote
Original assignee: Caterpillar Tractor Co
Current assignee: Caterpillar Inc
Priority date: 1971-04-19
Filing date: 1971-04-19
Publication date: 1973-08-14
Anticipated expiration: 1990-08-14

Abstract

A dual cooling system comprises first and second closed circuits, each circuit including an air-to-liquid radiator therein. The first circuit is adapted to cool an internal combustion engine whereas the second circuit functions to cool air discharged from a turbocharger to the intake manifold of an internal combustion engine. The system may comprise means for bypassing the radiators when temperature levels fall below predetermined levels and a single supply and expansion tank for supplying the two circuits with cooling fluid. A baffle is positioned in the tank''s chamber to divide it into two compartments with each compartment communicating with one of the circuits.

Description

United States Patent [191 Bentz et a1.

[ Aug. 14, 1973 Related US. Application Data [63] Continuation of Ser. No. 810,255, March 25, 1969,

abandoned.

[56] References Cited UNITED STATES PATENTS 3,451,511 6/1969 Knapp 188/264 E 3,439,657 4/1969 Gratzmuller 123/119 CD 3,336,911 8/1967 Steiber 123/119 CD 3,229,456 1/1966 Gratzmuller 123/119 CD FOREIGN PATENTS OR APPLICATIONS 877,557 9/1961 Great Britain 123/119 950,020 2/1964 Great Britain '123/119 Primary Examiner-Laurence M. Goodridge Assistant Examiner-Ronald B. Cox Attorney-Fryer, Tjensvold, Feix, Phillips & Lempio [571 1 ABSTRACT A dual cooling system comprises first and second closed circuits, each circuit including an air-to-liquid radiator therein. The first circuit is adapted to cool an internal combustion engine whereas the second circuit functions to cool air discharged from a turbocharger to the intake manifold of an internal combustion engine. The system may comprise means for bypassing the radiators when temperature levels fall below predetermined levels and a single supply and expansion tank for supplying the two circuits with cooling fluid. A baffle is positioned in the tanks chamber to divide it into two compartments with each compartment communicating with one of the circuits.

10 Claims, 4 Drawing Figures PAIENIE nun 1 4 ma SHEET 1 0F 4 INVENTORS ERWIN J. H. BENTZ ROGER D. HISEROTE PATENTEU AUG SHEET 2 BF 4 INVENTORS ERWIN J. H. BENTZ ROGER D. HISEROTE BY W 7 Y ATT PATENIED AUG 1 4 73 SHEET 3 0F 4 JJ INVENTORS ERWIN J. H. BENTZ ROGER D. HISEROTE I E I):

AT ozEYs wm mm PAIENTEU AUG 1 W SHEET 8 OF 4 INVENTORS ERWIN J. H. BENTZ ROGER D. HISEROTE BY WW4 w zrm DUAL COOLING SYSTEM FOR ENGINES This application is a continuation of Ser. No. 810,255, filed Mar. 25, 1969 and now abandoned.

The evolution of high performance internal combustion engines dictates the need for efficient cooling systems therefor. The heat loads imposed upon conventional radiators, employed in such cooling systems, has increased primarily due to the addition of cooling means for attendant engine hardware. For example, cooling means are normally employed to cool air discharged to the engine from a turbochargers compressor. It thus becomes desirable to increase the cooling capacity and efficiency of the overall cooling system in order to maintain the cooling fluids, usually water, at a suitable temperature to assure efficient engine operation.

One approach to such cooling problem is to employ a dual cooling system wherein one cooling circuit utilizes an air-to-liquid radiator to cool the engine whereas a second cooling circuit utilizes an air-to-air radiator to cool air discharged to the engine from the turbocharger. Air-to-air cooling requires rather lengthy piping which may cause unduly high back pressures or related disadvantages to engine performance. Such drawbacks have been alleviated to some extend by replacing the air-to-air radiator with an air-to-liquid radiator and by suitably redesigning the system to accommodate same.

An object of this invention is to overcome the above, briefly described problems by providing an economical and efficient dual cooling system for internal combustion engines. The system is basically of the latter type wherein an air-to-liquid radiator is employed in separate, first and second closed circuit means. A novel aspect of this invention comprises the utilization of thermostatically controlled bypass means in each of the circuits for bypassing coolant flow through the radiators when the temperatures of the circulated coolants fall below predetermined levels. The coolant is rather communicated directly to the inlets'to pump means employed in each of the circuits.

Another novel aspect of this invention is the provision of a single or common supply and expansion tank for supplying both the first and second circuit means with the same coolant. The tank has a baffle means arranged in a chamber thereof to divide the chamber into first and second compartments communicating with the first and second closed circuit means, respectively.

Other objects of this invention will become apparent from the following description and accompanying drawings wherein:

FIG. 1 schematically illustrates a first dual cooling system embodiment of this invention; and

FIGS. 2 through 4 schematically illustrate additional cooling system embodiments.

The FIG. 1 dual cooling system comprises first and second closed circuit means which may be subjected to conventional system pressures of psi, for example, for performing various cooling functions during engine operation. The first circuit means comprises a conventional air-to-liquid radiator 11 adapted to cool a first cooling liquid or coolant, preferably water, passed therethrough in a conventional manner. A fan 12, suitably connected to and driven by an output shaft of an internal combustion engine 13, may be employed in all described embodiments for inducing air flow through the radiators employed therein.

The inlet of an engine driven first pump means 14 is connected by conduit 15 to communicate with the lower manifold portion of the radiator. The coolant is then pumped through a conduit 16 attached to the pumps outlet, through a heat exchanger 17 and to an outlet conduit 18 connected to the engine. The heat exchanger may comprise an inlet 19 and outlet 20 adapted to circulate engine lubricating or transmission oil in heat exchange relationship with the coolant. The coolant is then circulated from outlet 18 of the heat exchanger through the engines conventional cooling jackets and passages and to an outlet conduit 21.

When the temperature of the coolant falls below a predetermined level, such as 200F., such coolant returns to conduit 15 at the inlet to pump 14 by thermostatically controlled bypass means comprising a bypass conduit 22. Such means further comprises a thermostatic valve 23 adapted to open when such temperature level is exceeded to communicate conduit 21 with a conduit 24 to permit the coolant to be returned to radiator 11. The radiator will function to suitably lower the coolants temperature whereafter it is recirculated by pump 14 in the aforementioned manner.

The second closed circuit means'comprises a second air-to-liquid radiator 25 having its lower manifold portion connected by a conduit 26 to the inlet of a second engine driven pump means 27. The pumps outlet is connected to a conduit 28 which communicates a second coolant to a heat exchanger 29 and thence to an outlet conduit 30. A turbocharger 31 is constructed and arranged to be driven in a conventional manner by exhaust gases emitted by engine 13 to deliver air in a conventional manner to the engines intake manifold via an inlet 32.

The air is thus cooled down from 350F. to l50F., for example, by heat exchanger 29 to improve engine operating efficiency. When the temperature of the coolant in conduit 30 falls below. a predetermined level a second thermostatically controlled bypass means, including a conduit 33, is provided for communicating the coolant to conduit 26 and the inlet to pump 27. However, when such temperature level is exceeded a thermostatic valve 34 of the second bypass means opens to communicate the coolant to a conduit 35 connected to the upper manifold portion of radiator 25.

FIG. 2 schematically illustrates a modification of the FIG. 1 system with similar constructions being depicted by identical numerals, with the numerals appearing in FIG. 2 being accompanied by a subscript a. The hereinafter described FIGS. 3 and 4 embodiments are likewise numbered, with the numerals appearing therein being accompanied by subscripts b and' c, respectively.

The second closed circuit means of the FIG. 2 system has a heat exchanger 36 added thereto for cooling the working fluid selectively communicated by control means (not shown) to a hydrodynamic retarder 37. It

. should be noted that the retarder is normally inacticloses such a retarder and integrated drive train. An outlet conduit 38 communicates such working fluid to heat exchanger 36 wherein it is passed in heat exchange relationship with respect to the second cooling fluid or coolant communicated therethrough from a pump outlet 28a to an outlet conduit 39. The working fluid .returns to the retarder through a return conduit 40.

The FIG. 2 system further comprises a single supply and expansion tank 41 operatively connected to the first and second closed circuit means. The tank has a vertically disposed wall or baffle means 42 secured therein to divide the tanks chamber into substantially separated and

isolated compartments

43 and 44. The baffle means preferably extends partly into a filler tube 45 having a pressure cap 46 removably attached thereto for filling purposes.

The baffle means is preferably composed of or coated with a conventional thermal insulative material for preventing any substantial heat conduction from occurring as between

compartments

43 and 44. In addition, an interconnecting passage 47 may be formed through the baffle means adjacent the upper end thereof, to equalize the pressures prevalent in the compartments. A conduit 48 communicates with compartment 44 and has a conventional relief valve 49 therein to prevent the pressure level in the tank from exceeding a predetermined, safe level.

A shunt conduit 50 communicates compartment 44 with a conduit a to selectively add water to the first circuit means whenever the circuits water level falls below a predetermined minimum, regardless of the position of a thermostatic valve 23a. A conduit 51 also communicates with compartment 44 to supply the required coolant to radiator 11a. The second circuit means also comprises a shunt conduit 52 to communicate compartment 43 with a conduit 260.

A conduit 53 communicates compartment 43 with radiator 25a.

Conduits

51 and 53 further provide means which compensate for any thermally induced expansions of the coolants maintained in the two circuit means. The remaining constructions and arrangements are substantially similar to corresponding ones shown in FIG. 1 and described above.

The FIG. 3 embodiment is similar to the above described embodiments except for the following structural and-function differences. A tank 41b has been modified to comprise first and second horizontally disposed baffle plates 54 and 55 having vent means or

tubes

56 and 57, respectively, extending therethrough. Thus compartments 43b and 44b are each divided into a pair of substantially equal sub-compartments. Such a baffle and venting arrangement aids in reducing unduly high water velocities to thus enable air, entrained in the water, to escape to increase cooling efficiency. Such a system is particularly adapted for use with radiators having no baffles therein.

It should be further noted that outlet conduit 21b of the first circuit means is connected directly between the engine's cooling jackets and the lower, subcompartment of compartment 44b. In addition, a thermostatic valve 23b is positioned in conduit 15b, between the outlet of radiator 11b and pump 14b, rather than in conduit 21b. An additional conduit 58 is connected to conduit 15b and conduit 51b between the expansion tank and the radiator. Thus the thermostatic valve will remain closed to permit the first coolant to be bypassed directly to the inlet to a pump means 14b via conduit 58 until the coolant's temperature exceeds a predetermined level. Thereafter fluid flow will be occasioned through the radiator to lower the coolant's temperature level.

The second closed circuit means finds an outlet conduit 39b from the retarder's cooler or heat exchanger connected directly to the lower, sub-compartment of compartment 43b. In addition, a conduit 59 is connected between a conduit 53b and a conduit 26b. Also, a thermostatic valve 34b is operatively connected between the radiator and conduit 26b, rather than in conduit 39b.

The FIG. 4 embodiment is substantially similar to the FIG. 3 embodiment except that horizontally disposed baffle plates 54 and 55 have been removed from a tank 41c. As suggested above, the FIG. 4 system would normally be employed when a baffle arrangement is placed in the radiators rather than in tank 41c, as in FIG. 3. An engine cooling systems outlet conduit 21c is thus connected directly to the upper manifold portion of a radiator 1 1c of the first cooling circuit. A conduit 39c, from a retarder cooler 360, is connected directly to the upper manifold portion of a radiator 25c of the second cooling circuit. In addition, bypass conduits 58c and 59c are connected to the upper manifold portions of their respective radiators rather than to the expansion tank directly.

We claim:

1. A dual cooling system in combination with an internal combustion engine having a turbocharger operatively associated therewith and a heat exchanger ope ratively associated with said turbocharger, said system comprising a first closed circuit means for circulating a first cooling liquid therethrough including in series a first air-to-liquid radiator, first pump means having an inlet communicating with said first radiator and an outlet communicating with an inlet to said engine for circulating said first cooling liquid therethrough and to an outlet thereof and first thermostatically controlled bypass means for normally circulating said first cooling liquid through said first radiator when the temperature of said first cooling liquid exceeds a predetermined level but for bypassing said first radiator and for communicating said first cooling liquid directly to the inlet to said first pump means when the temperature of said first cooling liquid falls below said predetermined level and a second closed circuit means for circulating a second cooling liquid, completely and constantly independent of first cooling liquid flow through said first closed circuit means, therethrough including in series a second air-to-liquid radiator, second pump means having an inlet communicating with said second radiator and an outlet communicating with an inlet to said heat exchanger for circulating said second cooling liquid therethrough and to an outlet thereof and a hydrodynamic retarder, including a bladed rotor mounted on a rotatable shaft and a stationary housing enclosing said rotor to form a chamber adapted to be filled with a working fluid, having a retarder heat exchanger operatively connected thereto for cooling and circulating a working fluid to said retarder, said retarder heat exchanger located in said second closed circuit means for circulating said working fluid in heat exchange relationship with said second cooling liquid, a single supply and expansion tank operatively connected to said first and second closed circuit means, said tank having a vertically disposed baffle means therein dividing a chamber of said tank into first and second substantially isolated compartments communicating with said first and second closed circuit means, respectively, and first and second horizontally disposed baffle plates in said first and second compartments, respectively, dividing each compartment into a pair of sub-compartments and vent means extending through each of said baffle plates to communicate each pair of sub-compartments with each other.

2. The invention of claim 1 further comprising second thermostatically controlled bypass means for normally circulating said second cooling liquid through said second radiator when the temperature of said second cooling liquid exceeds a predetermined level but for bypassing said second radiator and for communicating said second cooling liquid directly to the inlet to said second pump means when the temperature of said second cooling liquid falls below said predetermined level.

3. The invention of claim 1 further comprising another heat exchanger operatively connected in said first closed circuit means and to said engine for circulating engine oil in heat exchange relationship with said first cooling liquid.

4. The invention of claim 2 wherein said first bypass means is operatively connected between the outlet of said engine and said first radiator and wherein said second bypass means is operatively connected between the outlet of said heat exchanger and said second radiator.

5. The invention of claim 2 wherein said first bypass means is operatively connected between the outlet from said first radiator and said first pump means and wherein said second bypass means is operatively connected between an outlet from said second radiator and said second pump means.

6. The invention of claim 1 wherein said retarder heat exchanger is operatively connected between the outlet from said second pump means and the inlet to said turbocharger heat exchanger.

7. The invention of claim I wherein said retarder heat exchanger is operatively connected between the outlet from said turbocharger heat exchanger and said second radiator.

8. in a dual cooling system for an internal combustion engine, having a turbocharger operatively connected thereto, comprising a first closed circuit means, including a first air-to-liquid radiator, for circulating a first liquid therein to cool an internal combustion engine and a second closed circuit means, including a second air-to-liquid radiator, for cooling an auxiliary device, for circulating a second liquid therein, the invention comprising-a single supply and expansion tank having baffle means therein dividing a chamber of said tank into first and second substantially isolated compartments communicating with said first and second closed circuit means, respectively, for at least substantially equalizing pressures therebetween but for preventing intermixing of said first and second liquids, said baffle means is vertically disposed in the chamber of said tank and further comprising first and second horizontally disposed baffle plates in said first and second compartments, respectively, to divide each compartment into a pair of sub-compartments and vent means extending through each of said baffle plates to communicate each pair of sub-compartments with each other.

9. The invention of claim 8 wherein said tank further comprises a filler tube having a pressure cap removably attached thereto for filling purposes, said baffle means extending partly into said filler tube.

10. The invention of claim 8 wherein said baffle means is vertically disposed in the chamber of said tank and comprises a passage formed through said baffle means adjacent the upper end thereof to communicate said first and second compartments.

i i i i i

Claims

1. A dual cooling system in combination with an internal combustion engine having a turbocharger operatively associated therewith and a heat exchanger operatively associated with said turbocharger, said system comprising a first closed circuit means for circulating a first cooling liquid therethrough including in series a first air-to-liquid radiator, first pump means having an inlet communicating with said first radiator and an outlet communicating with an inlet to said engine for circulating said first cooling liquid therethrough and to an outlet thereof and first thermostatically controlled bypass means for normally circulating said first cooling liquid through said first radiator when the temperature of said first cooling liquid exceeds a predetermined level but for bypassing said first radiator and for communicating said first cooling liquid directly to the inlet to said first pump means when the temperature of said first cooling liquid falls below said predetermined level and a second closed circuit means for circulating a second cooling liquid, completely and constantly independent of first cooling liquid flow through said first closed circuit means, therethrough including in series a second air-to-liquid radiator, second pump means having an inlet communicating with said second radiator and an outlet communicating with an inlet to said heat exchanger for circulating said second cooling liquid therethrough and to an outlet thereof and a hydrodynamic retarder, including a bladed rotor mounted on a rotatable shaft and a stationary housing enclosing said rotor to form a chamber adapted to be filled with a working fluid, having a retarder heat exchanger operatively connected thereto for cooling and circulating a working fluid to said retarder, said retarder heat exchanger located in said second closed circuit means for circulating said working fluid in heat exchange relationship with said second cooling liquid, a single supply and expansion tank operatively connected to said first and second closed circuit means, said tank having a vertically disposed baffle means therein dividing a chamber of said tank into first and second substantially isolated compartments communicating with said first and second closed circuit means, respectively, and first and second horizontally disposed baffle plates in said first and second compartments, respectively, dividing each compartment into a pair of subcompartments and vent means extending through each of said baffle plates to communicate each pair of sub-compartments with each other.

7. The invention of claim 1 wherein said retarder heat exchanger is operatively connected between the outlet from said turbocharger heat exchanger and said second radiator.

8. In a dual cooling system for an internal combustion engine, having a turbocharger operatively connected thereto, comprising a first closed circuit means, including a first air-to-liquid radiator, for circulating a first liquid therein to cool an internal combustion engine and a second closed circuit means, including a second air-to-liquid radiator, for cooling an auxiliary device, for circulating a second liquid therein, the invention comprising a single supply and expansion tank having baffle means therein dividing a chamber of said tank into first and second substantially isolated compartments communicating with said first and second closed circuit means, respectively, for at least substantially equalizing pressures therebetween but for preventing intermixing of said first and second liquids, said baffle means is vertically disposed in the chamber of said tank and further comprising first and second horizontally disposed baffle plates in said first and second compartments, respectively, to divide each compartment into a pair of sub-compartments and vent means extending through each of said baffle plates to communicate each pair of sub-compartments with each other.