US2321882A

US2321882A - Method and means for cooling engine cylinders

Info

Publication number: US2321882A
Application number: US367259A
Authority: US
Inventors: John H Wallace
Original assignee: Individual
Current assignee: Individual
Priority date: 1940-11-26
Filing date: 1940-11-26
Publication date: 1943-06-15
Anticipated expiration: 1960-06-15

Description

June .15, 1943.

J; WALLACE 2,321,882

METHOD AND MEANS FOR COOLING ENGINE CYLINDERS 'Fileq Nov 26, 1940 2 Shee'ts-Sh eet 1 3/ o K, F 0 L /8/ I r J 7 HI} M g 34, 'I '"28 J u IM O f. BFg O 2 '27 .H V j 23 ;/-/6

/7 Q n N /.2 2 W //V|//VTOR.

- 5HNHI/1/4 mcE Wflfllaf ATTORNEY June I J. H. WALLACE 2,321,882

METHOD AND MEANS FOR COOLING ENGINE CYLINDERS I Filed NOV. 26, 1940 2 Sheets-Sheet Z nwnvrog JH/v H. We; 1. 196 5 ATTORNEY Patented June 15, 1943 UNITED STATES PATENT OFFICE v MIETIlOD MEANS FOR COOLING ENGINE CYLINDERS 1 John H. Wallace, Alhambra, Calif. Application November 26, 1940, sci-n1 No. 367,259

25 Claims.

' United States Patent No. 2,281,091, issued April 29, 1942) and bearing the filing date of April 26, 1940, I have disclosed a method of cooling an engine cylinder in vapor phase. In the method of cooling apparatus with which the present invention is concerned a novel difl'erence is established secondary circuit, the resultant flashing of the cooling medium to vapor, and its subsequent condensation in the secondary circuit while maintaining the primary circuit completely filled at all times.

The present invention contemplates the practice of a method of cooling with a structure which includes a cooling jacket and a closed system of conduits constituting a primary circuit, the primary circuit being fllled constantly with a cooling medium which circulates therethrough due to thermal or mechanical action, and in connection with which primary circuit a secondary circult is provided including conduits, mechanical over methods heretofore employed, in that two cooling fluid circuits are established, a primary cooling fluid circuit, which includes the cooling jackets of a piece of apparatus and which ciruit and jackets are completely fllled at all times with a continuously circulating cooling fluid, and a secondary cooling fluid circuit disposed in heat exchange relationship with the primary cooling circuit and provided with means whereby a transfer of heat fromthe primary cooling circuit may be made to the secondary cooling circuit to raise the temperature of a cooling medium within the secondary circuit to boiling, and to thereafter condense the vapors of a cooling medium in the secondary circuit, whereby the secondary cooling liquid and condensate may be maintained in circulation. The present method contemplates that the primary and secondary cooling circuits may be completely separated from each other without commingling of the fluids in the two circuits or may be arranged so that at a point in the two circuits cooling liquid and vapor is liberated from the primary circuit and into the secondary circuit, while cooling liquid is constantly introduced into the primary circuit from the secondary circuit in a volume in excess of the rate of evaporation of the cooling fluid in the primary circuit, since in either of the methods it is essential that the primary circuit be filled completely with the cooling'medium at all times. It is the principal object of the present invention, therefore, to provide a method and means of establishing and'maintaining the two aforesaid circuits of cooling fluid whereby the temperature of the fluids in the primary circuit will be maintained at a predetermined temperature by the interchange of heat from the primary circuit to the circulating means and vapor condensing apparatus, the said circuits being in heat exchange relationship to each other with or without actual commingling o! the fluids of the two circuits, whereby the fluids of the primary circuit will be controlled to maintain a predetermined temperature.

The invention is illustrated by way of example in the accompanying drawings, in which:

Figure 1 is -a view in diagram showing an engine equipped with one form of the present invention and in which an automatic valve maintains pressure in the system.

' Fig. 2 is an enlarged view in vertical section showing one form of the back pressure valve.

Fig. 3 is a view showing a diiferential back pressure valve.

Fig. 4 is a view in diagram showing a form of apparatus by which the present invention may be practised and within which the cooling fluids vof the primary and secondary circuits are in heat exchange relationship with each other but This engine is preferably of standard design and construction and is fitted with a circulating pump l3 driven by suitable means ll. Mounted upon the engine is a back pressure valve structure I5 which in simple form is shown in Fig. 2 of the drawings. This valveincludes an outer housing It having a lower chamber l1 and an upper chamber I 8 separated therefrom by a partition IS. A valve opening and seat 20 is formed through the partition. The lower chamber ll communicates with manifold I! through connection 12' and return conduit 22 leading to the induction side of the pump I! through connection 22'. The valve seat 28 receives a valve element 23. A spring 28 acts to hold this valve element on its seat. This spring is of a predetermined capacity to temporarily resist the opening of the valve 23. An outlet conduit 21 leads from the upper'chamber [8 within the valve housing l8 and communicates witha tank 28 in the bottom of a condenser 29. At the top of the core of this condenser is a header 38 fitted with a vent 3|. This vent may be open if desired, although in some instances it may be preferable to close this vent. The tank 28 receives the liquid and vapors liberated and passed through valve 23 and into the upper chamber l8 of the valve housing l8, and thereafter conducted through the conduit 21. These liquids and vapors when condensed will accumulate within the tank 28, after which they are delivered through a conduit 33 and a condensate pump 34 to a conduit 35 which leads to the lower chamber ll of the housing l6 of the pressure valve It. It is desirable to place a check valve 38 in the line 35. This check valve 36 is provided in order that a pressure indication may be obtained on the secondary circuit independent of the primary circuit pressure. Thus a failure of the secondary flow may be indicated.

Referring to Fig. 3, of the drawings, a variation A of the back pressure valve is shown in which a differential pressure control is provided as determined by the volume and pressure of the fluid in the condensate line 35. The condensate line is fitted with the check valve 36' and leads to chamber ll of the housing l6 of the back pressure valve l5. Within the housing and disposed beneath the valve element 23 is a rigidly supported Sylphon bellows which communicates with a condensate line 46 connected with the condensate line 35 at a point between the pump 34 and the check valve 36'. This provides a differential pressure control for the back pressure valve I5 in a manner which will be hereinafter clearly explained. A

In operation of the form of the invention shown in Figs. 1 and 2 of the drawings, the cooling jacket of the engine is filled with liquid up to substantially the level of the valve seat 23. This constitutes the primary cooling circuit. The check valve 36' will prevent a return flow of this liquid into the condensate line 35 and the tension of the spring 26 will prevent the valve 23 from rising until a predetermined pressure condition prevails, which will be hereinafter explained. When the engine I0 is started the circulating pump l3 will be driven and will force the water into the distributing manifold II and the engine block, after which it will pass through the discharge manifold 12 and the conduit I2 into the housing I6 of the back pressure valve I5. This water may then circulate freely into the conduit 22 which will return it to the engine jackets by action of the circulating pump l3.

At the same time the primary cooling circuit is being maintained the secondary cooling circuit is functioning. This secondary circuit operates through the pump 34 to withdraw accumulated liquid from the tank 28 and to deliver it into the housing of the back pressure check valve IS. The quantity of liquid which is delivered by the con- Since there is no appreciable cooling of the liquid in the primary circulatory cycle, as previously described, it will be evident that the liquid will be raised rapidly to the boiling point. When the liquid reaches a boiling temperature, as determined by the back pressure valve IS, the valve 28 will be raised from its seat to allow the fluid to pass into the conduit 21. This will relieve the fluid pressure instantly within the pressure valve structure I! and will cause the liquid to flash into vapor. The vapor and liquid which then pass over into the conduit 21 of the secondary circuit will move downwardly through the conduit to the tank 28 at the bottom of the condenser 29.

Attention is directed to the fact that while provisions are made for the condensation of vapors expelled from the primary circulating system that this does not contemplate the direct circulation of said fluids through cooling or condensing apparatus. The mixed fluids are. delivered to the bottom of a condenser and the vapors are free to rise in the condenser until condensation takes place, after which they fall into the tank 28 and replenish the liquid supply of the secondary circuit. Thus, there is no restricted action upon the vapors as might occur if these vapors were forced through a condenser or the like in direct flow. This arrangement is of particular importance due to the phenomenon which occurs in apparatus of the type concerned and which is brought about by latent heat within the cooling jacket of the engine. It is to be borne densate pump 34 is in excess of the volume of in mind that this cooling system may be applied upon. an engine operating at varying speeds and varying loads, and that at times after the engine has been in operation it will be shut down completely. When the engine is shut down circulation within the primary and secondary cooling fluid circuits is stopped, and since there is no element in the primary circuit to produce a cooling action the latent heat of the engine structure and the non-circulating primary cooling fluid will cause that fluid to rise in temperature and to be forced through the back pressure valve I5, where it will flash into steam and will pass through the conduit 21 to the bottom of the condenser 29 and will rise in the condenser to a height proportionate to its own pressure and volume without restriction except that imposed by friction along the walls of the conduit. Any air in the system will be displaced through the vent 3|. The condensate will accumulate in the tank 28 and will be returned to the housing of the pressure valve l5 through the conduit 35 and the check valve 38.

By this arrangement it will be seen that a substantially constant pressure will be maintained within the primary circulation circuit, and that likewise a substantially constant temperature will be maintained, since temperature and pressure have a definite relationship to each other. It is to be pointed out that the rate of delivery of condensate by the secondary pump 34 will insure continuous filling of the primary circuit and thus maintain a substantially constant pressure in the circulating system. The valve structure shown in Fig. 3 may be used when it is desired to increase the heat storage capacity of the liquid within the primary circuit. The valve, as shown, will increase the pressure during engine shut down periods, thus raising the boiling point of the liquid and thereby providing a heat storage reservoir. It will be seen that the pressure of the condensate flowing through the conduit 43 to the Sylphon bellows 45 will have an independent and differential action on the movement 01' the valve element 23. By offsetting the pressure of spring 26 during operation'the bellows lowers the effective ressure within the primary circuit and conversely increases this pressure during shut down periods. When the regular circulation pump is used a constant pressure is maintained and set at any predetermined value by adjustment of the spring 26 and the action of the back pressure valve 36. By maintaining a substantially constant pressure in the primary cooling system and producing the concentration of the flashing of the steam, it is possible for the apparatu to be of relatively small capacity while insuring that the cooling jacket of the engine shall be fllled with cooling fluid at all times.

It is to be understood that while regulation of fluid pressure within the engine circuit is controlled optionally in the present disclosure by the back pressure valve i5 that the apparatus will function satisfactorily by providing a discharge orifice of a selected area through which the excess fluids from the primary circuit may pass into the secondary circuit.

Attention is also directed to the fact that due to the arrangement of the condensate conduit with its back pressure valve and its circulating pump 34, it is insured that the condensate pump and the conduit 35 will be maintained full of fluid at all-times. This condition will prevail regardless of the angular position of the engine. In this connection it should be pointed out that while the invention has been described as using water, various cooling compounds might be used, such as those developing non-condensing vapors. When this is done the vent valve 32 may be closed completely after all of the air has been exhausted from the circulating system.

Referring more particularly to the form of the invention shown in Fig. 4, a primary circuit conduit 50 is indicated in series with the engine jacket II. A secondary circuit, 5! is indicated in series with a condenser 29 and the circulating pump 34. The two circuits are disposed in heat exchange relationship with each other through the heat exchanger 52. It will be obvious that there will not be any boiling of the cooling medium in the entire system until sufiicient heat is transmitted from the primary circuit to' produce boiling in the secondary circuit, and it will 'be seen that as the fluid in the secondary circuit passes to the condenser 29 as mixed vapor and liquid, the fluid will be reduced again to liquid for re-circulation.

It will thus be seen that the method and means here shown for cooling an engine of the type described is decidedly simple in construction, comprises few moving parts, and insures proper cooling of the engine under constant pressure and temperature without the use of cooling instrumentalities and without reference to the an- 1 engine or the like, said engine being fitted with m a jacket to receive a cooling' fluid, which method consists in establishing a primary cooling fluid circuit through the jackets, a secondary continuously circulating cooling fluid circuit in communication with the primary cooling circuit and delivering cooling fluid thereto independently of the rate of evaporation of the coolingfluid in.

the primary circuit, and whereby said secondary circuit will cause cooling liquid to be introduced into the primary circuit and cooling fluids to be liberated therefrom to accomplish cooling of the primary circuit by heat transfer to the delivered fluid from the secondary circuit.

2. A method of cooling an internal combustion engine or the like, said engine being fitted with a jacket to receive a cooling fluid, which method consists in establishing a primary cooling fluid circuit through the jackets, a secondary continuously circulating cooling fluid circuit in communication with the primary cooling circuit and delivering cooling fluid thereto independently of the rate of evaporation of the cooling'fluid in the primary circuit, and whereby said secondary circuit will cause cooling liquid to be introduced into the primary circuit and cooling fluids to be liberated therefrom to accomplish cooling of the primary circuit by heat transferto the delivered fluid from the secondary circuit and the liberated steam from the primary circuit, and thereafter bringing about condensation of the liberated steam and introducing said condensate into the flow stream of the secondary circuit.

3. A method of cooling an internal combustion engine or the like, said engine being fitted with a jacket to receive a cooling fluid, which method consists in establishing a primary cooling fluid circuit through the jackets, circulation of fluid through said circuit being continuous and at a uniform rate, a secondary continuously circulating cooling fluid circuit in communication with the primary cooling circuit and delivering cooling fluid thereto independently of the rate of evaporation of the cooling fluid in the primary circuit, and whereby said secondary circuit will cause cooling liquid'to be introduced into the primary circuit and cooling fluids to be liberated therefrom to accomplish cooling of the primary circuit by heat transfer to the delivered fluid from the secondary circuit.

4. A method of cooling an internal combustion engine or the like, said engine being fitted with a jacket to receive a cooling fluid, and which consists in establishing a primary cooling circuit through the engine jacket while maintaining said circuit constantly filled with the circulating fluid,

a secondary continuously circulating closed cooling fluid circuit having entry and exit to the primary cooling circuit and including means for maintaining a constant circulation of cooling fluid in the secondary circuit irrespective of the rate of evaporation of cooling fluid in the primary circuit, whereby a constant in-put of cooling liquid will be made from the secondary circuit to the primary circuit, thus maintaining the primary circuit completely filled with cooling fluid and a constant liberation of excess fluids may take place from the primary circuit to the secondary circuit, and then creating an auxiliary action upon the fluids of the secondary circuit whereby condensation of the steam will take place.

- 5. A method of cooling an internal combustion engine or the like, said engine including a cooling jacket, which method consists in maintaining a cooling fluid within a closed primary circuit 7 including the cooling jacket, then establishing a secondary closed cooling fluid circuit while maintaining constant circulation of fluid therethrough, then creating intercommunication between the two cooling fluid circuits whereby cooling fluids from the primary circuit are liberated into the secondary circuit and cooling liquid from the secondary circuit is introduced into the primary circuit in a volume in excess of volume of cooling fluid evaporated from the primary circuit, whereby the primary circuit will be maintained filled with cooling fluid at all times, and then liberating vapors from the flow stream of the secondary circuit to condense the same, and thereafter introducing the condensate into the flow stream of the secondary circuit.

6. A method of cooling an internal combustion engine or the like, said engine including a cooling jacket, which method consists in maintaining a cooling fluid Within a closed primary circuit including the cooling jacket, then establishing a secondary closed cooling fluid circuit while maintaining constant circulation of fluid therethrough, then creating intercommunication between the two cooling fluid circuits whereby cool ing fluids from the primary circuit are liberated into the secondary circuit and cooling liquid from the secondary circuit is introduced into the primary circuit in a volume in excess of volume of cooling fluid evaporated from the primary circuit, whereby the primary circuit will be maintained filled with cooling fluid at all times, and then liberating vapors from the flow stream of the secondary circuit to condense the same, and thereafter introducing the condensate into the flow stream of the secondary circuit, the primary circuit being maintained at a predetermined fluid pressure to establish a predetermined temperature of the cooling fluid therein.

7. A method of cooling an internal combustion engine or the like, said engine including a cooling jacket, which method consists in maintaining a cooling fluid within a closed primary cooling circuit including the cooling jacket and without the provision of cooling apparatus in said circuit, then establishing a secondary closed cooling fluid circuit including a liquid storage tank from which cooling liquid is constantly introduced into the primary cooling circuit in a volume in excess of the volume of evaporation of the cooling fluid within the primary circuit to maintain the primary circuit filled, while discharging excess fluids from the primary circuit into the secondary circult, after which they are delivered to the storage tank included within the secondary circuit and the vapors may be caught into the tank in the form of condensate.

8. A method of cooling an internal combustion engine or the like, said engine including a cooling jacket, which method consists in maintaining a cooling fluid within a closed primary cooling circuit including the cooling jacket and without the provision of cooling apparatus in said circuit, then establishing a secondary closed cooling fluid circuit including a liquid storage tank from which cooling liquid is constantly introduced into the primary cooling circuit in a volume in excess of the volume of evaporation of the cooling fluid within the primary circuit to maintain the primary circuit filled, while discharging excess fluids from the primary circuit into the secondary circuit, after which they are delivered to the storage tank included within the secondary circuit and the vapors may be caught into the tank in the form of condensate, a predetermined pressure being maintained within the primary cooling circuit by an orifice of selected area through which the excess fluids pass from the primary cooling circuit into the secondary circuit.

9. A method of cooling an internal combustion engine or the like, said engine including a cooling jacket, which method consists in maintaining a cooling fluid within a closed primary cooling circuit including the cooling jacket and without the provision of cooling apparatus in said circuit, then establishing a secondary closed cooling fluid circuit including a'liquid storage tank from which cooling liquid is constantly introduced into the primary cooling circuit in a volume in excess of the volume of evaporation of the cooling fluid within the primary circuit to maintain the primary circuit filled, while discharging excess fluids from the primary circuit into the secondary circuit, after which they are delivered to the storage tank included within the secondary circuit and the vapors may be caught into the tank in the form of condensate,

a predetermined pressure being maintained within the primary cooling circuit by a yieldable check valve responsive to a predetermined excess pressure in the primary circuit, at which time excess fluids from the primary circuit will enter the secondary circuit to relieve the excess volume of fluids from the primary circuit and to thereby maintain the primary circuit at a constant pressure and a resulting constant temperature.

10. In combination with the cooling jackets of an internal combustion engine or the like, a closed cooling medium flow circuit including the cooling jacket, whereby cooling fluid will circulate in said path of flow as the engine operates, an outlet in said circulating circuit, a pressure valve normally closing said outlet and acting to relieve the pressure when it exceeds a predetermined value, and an expansion chamber within which said relieved fluid is liberated, said expansion chamber being under a normal condition of reduced pressure as compared to the pressure in the fluid circulation path, whereby the released fluid will flash into steam.

11. In combination with the cooling jackets of an internal combustion engine or the like, a closed cooling medium flow circuit including the cooling jacket, whereby cooling fluid will circulate in said path of flow as the engine operates, an outlet in said circulating circuit, a pressure valve normally closing said outlet and acting to relieve the pressure when it exceeds a predetermined value, an expansion chamber within which said relieved fluid is liberated, said expansion chamber being under a normal con dition of reduced pressure as compared to the pressure in the fluid circulation path, whereby the released fluid will flash into steam, means for condensing said steam, and means for returning the condensate to the fluid circulation :the other in communication therewith, a pressure responsive valve element normally interrupting said communication, a conduit leading from said second named compartment, a condenser with which said conduit communicates continuously and whereby fluid relieved from the normal flow circuit by the opening of the pressure valve may be conducted to the condenser, and means for returning-condensate from the condenser and re-introducing it into the normal fluid flow through the engine Jacket.

13. In combination with the fluid cooling jacket of an internal combustion engine or the like, a fluid cooling medium circulating pump. a conduit leading fluid from said pump into the cooling jacket and a return conduit from the cooling jacket to the circulating pump, whereby a constant flow of a fluid cooling medium will be maintained at a predetermined flow pressure, a pressure responsive valve housing interposed between the conduits and through which said fluid passes in its normal flow, said valve housing being divided into two compartments, one through which the fluid may flow continuously, the other in communication therewith, a pressure responsive valve element normally interrupting said communication, a conduit leading from said second named compartment, a condenser with which said conduit communicates continuously and whereby fluid relieved from the normal flow circuit by the opening of the pressure valve may be conducted to the condenser, means for returning condensate from the condenser and re-introducing it into the normal fluid flow through the engine jacket, and a back pressure check valve in sa d condensate flow line.

.14. In comb nation with the fluid cooling jacket of an internal combustion engine or the like, a fluid cooling medium circulating pump, a conduit leading fluid from said pump into the cooling jacket and a return conduit from the cooling jacket to the circulating pump,

whereby a constant flow of a fluid cooling medium will be maintained at a predetermined flow pressure, a pressure responsive valve housing interposed between the conduits and through which said fluid passes in its normal flow, said valve housing being dividedinto two compartments, one through which the fluid may flow continuously, the other in communication therewith, a pressure responsive valve element normally interrupting said communication, a conduit leading from said second named compartment, a. condenser with which said conduit communicates continuously and whereby fluid relieved from the normal flow circuit by the opening of the pressure valve may be conducted to the condenser, means for returning condensate from the condenser and re-introducing it into the normal fluid flow through the engine jacket, a back 6 pressure check valve in said condensate flow line, and means for establishing the predetermined pressure of fluid in the main path of flow at which the pressure valve will open to temporarily permit the relief of fluid from the main flow line and whereby the valve will close when said pressure equilibrium has been reestablished.

15. A cooling apparatus for the fluid cooling jacket of an internal combustion engine or the like, comprising a fluid circulating pump, a conduit establishing communicati n between said pump and the cooling jacket, a pressure valve housing comprising a pressure flow chamber and a pressure relief chamber, a partition dividing the same formed with a valve opening therev the opening from the flow chamber to the relief through, a conduit frbm the jacket to the pressure flow chamber, a conduit from the pressure flow chamber to the circulating pump, a pressure responsive valve. element normally closing the opening from the flow chamber to the relief chamber and set to open in response to a predetermined pressure, a conduit leading from the pressure relief chamber, a condenser with the bottom of which said conduit communicates, a reservoir at the bottom ofthe condenser to receive condensate from the condenser, a conduit from the reservoir to the flow line of the fluid passing through the circulating pump, a condensate pump within said flow line, and a back pressure valve in said condensate line.

16. A cooling apparatus for the fluid cooling jacket of an internal combustion engine or the like, comprising a fluid circulating pump, a conduit establishing communication between said pump and the cooling jacket, a pressure valve housing comprising a pressure flow chamber and a pressure relief chamber, a partition dividingv the same formed with a valve opening therethrough, a conduit from the jacket to the pressure flow chamber, a conduit from the pressure flow chamber to the circulating pum a pressure responsive valve element normally closing chamber and set to open in response to a predetermined pressure, a conduit leading from the pressure relief chamber, a condenser with the bottom of which said conduit communicates,

' a reservoir at the bottom of the condenser to receive condensate from the condenser, a conduit from the reservoir to the flow line of the fluid passing through the'circulating pump, a condensate pump within aid flow line, a back pressure valve in said condensate line, and a vent at the top of the condenser whereby excessive fluid may be relieved from the system.

17. A cooling apparatus for the fluid cooling jacket of an internal combustion engine or the like, comprising a fluid circulating pump, a conduit establishing communication between said pump and the cooling jacket, a pressure valve housing comprising a pressure flow chamber and a pressure relief chamber, a partition dividing the same formed with a valve opening therethrough, a conduit from the jacket to the pressure flow chamber, a conduit from the pressure flow chamber to the circulating pump, a pressure responsive valve element normally closing the opening from the flow chamber to the relief chamber and set to open in response to a predetermined pressure, a conduit leading from the pressure relief chamber, a condenser with the bottom of which said conduit communicates, a reservoir at the bottom of the condenser to receive condensate from the condenser, a conduit from the reservoir to the flowline of the fluid passing through the circulating pump, a condensate pump within said flow line, a back pressure valve in said condensate line, a vent at the top of the condenser whereby excessive fluid may be relieved from the system, and a valve by which the vent may be closed.

18. In combination with the fluid cooling jacket of an internal combustion engine or the like, a fluid cooling medium circulating pump, a conduit from said pump to the engine jacket, a pressure valve housing formed with a flow pressure chamber and a relief pressure chamber, a partition dividing the chambers and being formed with a valve opening therethrough, a valve element normally closing the opening to resist flow of fluid from the pressure flow chamber to the pressure release chamber, means for setting said valve element to open at a predetermined pressure, a conduit from the cooling jacket to the flow chamber of the valve housing, a conduit from the flow chamber to the induction side of the circulating pump, a condenser, a conduit from the relief chamber of the valve housing to the bottom of the condenser, a condensate reservoir at the bottom of said condenser to receive condensate from the condenser, a condensate pump, a condensate pipe from the reservoir to said pump, a condensate pipe from the pump to the flow chamber, a back pressure check valve in said line from the condensate pump to the flow chamber, and fluid responsive means connected with said condensate pipe and acting upon the pressure valve in cooperation with the pressure of the fluid passing through the flow chamber, whereby the total pressure in the flow chamber will act against the valve, its spring and the pressure in the relief chamber to cause the pressure valve to be open when a predetermined total pressure is created in the flow chamber.

19. In combination with a jacketed internal combustion engine, means providing a primary cooling fluid circuit which includes the jacket of the engine, means providing a secondary'cooling fluid circuit in heat exchange relationship to the primary circuit, a pump in the secondary circuit, and a vented condenser in the secondary circuit.

20. In combination with a jacketed internal combustion engine, means providing a primary cooling fluid circuit which includes the jacket of the engine, means providing a secondary cooling fluid circuit in heat exchange relationship to the primary circuit, a pump in the secondary circuit, and a vented condenser in the secondary circuit, said secondary circuit including a liquid reservoir arranged to supply the pump with liquid at all times.

21. In combination with a jacketed internal combustion engine, means providing a primary cooling fluid circuit including the jacket of the engine, means providing a secondary cooling fluid circuit including a pump and a condenser,

and means responsive to pressure in the primary circuit for opening the primary circuit to the secondary circuit.

22. In combination with a jacketed internal combustion engine, means providing a primary cooling fluid circuit including the jacket of the engine, means providing a secondary coolingfluid circuit including a pump, a vented condenser, and means normally closing the primary circuit against egress of cooling fluid therefrom into the secondary circuit but responsive to pressure in the primary circuit to open the primary circuit to the secondary circuit,

23. In combination with a jacketed internal combustion engine, means providing a primary cooling fluid circuit including the jacket of the engine, means providing a secondary cooling fluid circuit including a pump and a vented condenser, a valve controlling communication between the primary circuit and the secondary circuit, and spring means urging said valve into closed position, said valve being responsive to pressure in the primary circuit exceeding a predetermined degree to open the primary circuit to the secondary circuit.

24. In combination with a jacketed internal' combustion engine,-means providing a primary cooling fluid circuit including the jacket of the engine, means providing a secondary cooling fluid circuit including a pump and a condenser, pressure responsive means for opening the primary circuit to the secondary circuit, the secondary circuit having a check valve controlled return to the primary circuit.

25. In combination with a jacketed internal combustion engine, means providing a primary cooling fluid circuit including the jacket of the engine, means providing a secondary cooling fluid circuit including a pump and a condenser, a valve responsive to pressure in the primary circuit for opening the primary circuit to.the secondary circuit when pressure in the primary circuit exceeds a predetermined degree, the secondary circuit having a check valve controlled return to the primary circuit at a point adjacent said valve.

JOHN H. WALLACE.