US2086442A - Cooling system for internal combustion engines - Google Patents

Description

y 1937. s. w. RUSHMORE 2,085,442

COOLING SYSTEM FOR INTERNAL COMBUSTION ENGINES Filed March 27, 1935 INVENTOR ATTORNEY Patented July 6, 1937 UNITED STATES PATENT OFFICE COOLING SYSTEM FOR INTERNAL COM- BUSTION ENGINES 20 Claims.

My present invention relates to an engine cooling system which resembles that described in my Patent No. 1,651,157, granted November 27, 1927, in that the cooling circuit discharges water from 5 the bottom of the radiator into the upper part of the engine jacket, at a point near the outlet through which water and/or steam returns to the radiator, so that the water normally flows through a relatively short, low resistance path,

0 past the main body of water in said jacket; also in the further particular that the fiuid-interchange communication between said normal flow path and the jacket is restricted so as to properly limit the amount of interchange that can be induced by thermocirculation and boiling in the jacket.

In said patent the cooling circuit is shortcircuited through the bottom of the radiator so' that the latter operates as an upflow condenser, but my present system is like that set forth in my pending application Ser. No. 735,619, filed July 17, 1934, and, particularly Ser. No. 741,396, filed August 25, 1934, in both of which the cooling circuit is of the conventional water cooling type with a pump circulating the water by topto-bottom downflow in a radiator designed to take care of the maximum cooling requirements of the engine merely by water cooling, without steam condensation. In both said applications, 30 as in the patent, the means for restricting the fluid-interchange communication between the cooling circuit and the jacket includes walls defining a small chamber communicating with the jacket through openings afiording the desired resistance or obstruction to flow ther-ethrough.

While I prefer to employ a similar chamber in my present system, an important feature is the discovery that a more distributed flow-impedance and temperature-equalizing medium such as cop- 40 per wire netting, may be used so as to render a separate walled chamber unnecessary.

I have discovered that such a medium has other important advantages. It permits an interchange of cooling fluid between the chamber and the jacket which is characteristically similar to that in said applications, that is, simultaneously in both directions, under certain conditions; and under other conditions, alternating, steam or steam-foamed water flowing from the head jacket into the chamber and then water from the chamber into the jacket, but it controls said interchange in a much better way. For instance, in said applications, under conditions of boiling in the jacket, the forcing of the steam directly into water cool enough to have a condensing effect,

may produce a loud snapping noise, sometimes so violent as to be almost unbearable; but when the wire net medium in the path of interchange of cooling medium between the short circuited path and the jacket, extends for a sufficient distance and is properly designed, there is no noise.

Another distinct and wholly unexpected advantage of the wire net medium is that it renders unnecessary the thermostatic inlet valve, employed in-the systems of said earlier applications.

Another distinct advantage is that such wire net medium modifies the alternating rushes of steam and water, without preventing their useful water supplying and steam and air expelling functions, thereby making it practical to dispense with the supplemental water-supplyreservoir of said application Ser. No. 741,396; and also co operating with a check valve which I have added in the car heater line to render the radiator much more efficient. As to the car heating features this application is a continuation in part of my concurrently pending application, Ser. No. 741,396, filed August 25, 1934.

The above and other features of my invention may be more fully understood from the following description in connection with the accompanying drawing, in which Fig. 1 is a side elevation conventionally indicating a common type of four-cylinder automobile engine, to which my invention may be applied;

Fig. 1a is a transverse section through the radiator filler cap;

Fig. 2 is a section on the line 22, Fig. 1;

Fig. 3 is a sectional View showing one form of wire gauze units which may be arranged to af- 3 ford the desired distributed flow impedance; and

Fig. 4 is a similar view of a modification. In this drawing like parts are indicated by like numerals; and the parts similar to those in my prior application Ser. No. 741,396, are as follows:

The upper ends of engine cylinders l are surrounded by the conventional water jacket 2 communicating through openings 3, 3, with the water jacket space 4 of the head block 5. The cooling circuit includes the uptake pipe 6, discharging into the upper header or tank I, through which the water and/or steam cooling medium flows downward through the honeycomb or tubular air-cooled conduits 8 to the bottom tank 9 and through return conduit 10, to the water jacket of the head. The air draft is drawn through the radiator cooling elements 8 by fan Ii on shaft l2 and is driven from the engine by belt 13. Circulation of water through the ove circuit is assisted by a suitable pump, in

this case a rotor H! such as commonly employed on the Ford motor to assist thermo-circulation of water from the head jacket and into the uptake conduit 6. The pump could be located in the low level part of return conduit ID, as is more common, but there are advantages in employing the high level suction pump in connection with my present invention, which will be explained in due course.

Means for utilizing the cooling capacity of this circuit so as to ensure boiling in the water jacket under average conditions, without danger of escape of steam under special conditions of maximum heat evolution in the cylinder, may include a chamber i6 into which the cool water return pipe 10 discharges, and from which the uptake pump I4 assists flow of water into the uptake conduit 6. As shown in Fig. 2, this chamber may be formed by a side wall I I, and end wall 3, the roof of the combustion chamber constituting the bottom of the chamber and the top being closed in by a plate 20. Such chamber has fluid-interchange communication with the head jacket space through one or more openings as at 2|, said opening or openings being preferably in the wallof the chamber which is opposite to the intake of the pump. In the present case, the amount of restriction afforded by such chamber and openings, is not so important and it may be much less than in said application, because of the distributed fiow impedance, which is the most important feature of my present invention.

As indicated by the arrows in Fig. 2, the water supply to the jacket flows out through opening 2| and steam or hot water can flow in the reverse direction, from the head jacket 4 into the chamber I6, either simultaneously in opposite directions through different parts of the opening; or alternately, steam or steam-foamed hot water flowing from the jacket into chamber l6 and then water from chamber 16 into the jacket.

In the preferred form shown in the drawing, the chamber 16 is filled with separate, hollow, shell-like bodies 23, made from wire netting which is preferably of copper so as to be a good conductor of heat. Other coarser or finer metal filling material in various sizes and shapes may be successfully employed provided it is evenly divided and contains no very large voids, but I prefer separate, contacting, elastic units made from copper mosquito netting, say 16 mesh; and preferably in the form of small spheres. Single pieces of netting about 4 inches square: may be crimped or folded to more or less uniform size; or, as shown in Fig. 4, may be punched to cup shape, as at 23x, 23y, and the edges bent in, as at 23c; or, as indicated in Fig. 3, half spheres 23a, 231), may be punched out and then assembled by slightly telescoping the free edges as at 230 so that the prickly ends of the wires mesh together. successively, as formed, those spheres may be arranged in the front end of the head jacket, in contact with one another and under slight pressure such that their elasticity will prevent undue shifting of the spherical units. The spheres are prevented from displacement through the water inlet into pipe l0 and through the outlet to the pump by suitable means such as coarse netting at I01) and Nb. Although the wire mesh bodies, preferably spheres, are pressed together to some extent, nevertheless due to the primarily convex configuration of the surfaces thereof, there are in practice very few fiat-to-fiat contacts, and passages between the spheres afford correspondingly small, yet very useful impedance to flow of water or steam therethrough. The netting affords impedance to flow therethrough which is somewhat greater and far more variable in effect.

In the preferred arrangement shown in Fig. 2

. of the drawing,- the above describedfiow impedance medium extends through restricted opening 2| in the wall of chamber l6 and for a substantial distance beyond and around said opening, preferably several inches. In order to holdthese exterior spheres in uniform stable relation the same as those inside of the chamber, it is desirable to provide suitable means for confining them as, for instance, walls l'la and -l8a having openings therethrough small enough to prevent passage of the spheres but of combined area suflicient so that their restricting effect on flow of water or steam therethrough is practically negligible.

With the above described flow-impeding, heatconducting medium filling the chamber 16, and

extending beyond the restricted opening, as above yet 2 inches or so, outside of opening 2 I, the temperature of fluid in the medium will be held at 212 on all loads. It follows that if the medium is extensive enough and designed to offer sufficient distributed impedance, it becomes possible to dispense with chamberlfi, and to operate without having an empty gap in the top tank of the cooling circuit, in addition to dispensing with the thermostatic valve and the supplemental water supply tank of said application, Ser. No. 741,396. In said application, normal operating condition is attained when the circuit is filled only to the level of test cock 30, as shown, in Fig. 1; but even if entirely filled, actual driving the engine will eventually result in blowing out excess water until the level is below the bottom of reservoir 1. 7

Tank 7 and those parts of uptake pipe 6 and core 8 which are above the normal water level,

form a gap in the water circuit, the pump 4 being primarily designed merely for assisting thermo-circulation through the circuit when the upper tank is full of water. Consequently, with the present empty gap in the upper part of the circuit, such pump will not be powerful enough to suck down the water level in the radiator core 8 and push it up in pipe 6 to the extent which would be necessary to force water circulation through the top tank 1. Consequently, in operation, water in the engine jacket soon reaches the boiling point; and it is only when it boils hard enough, that the steam in combination with the pump, is able to lift the water in uptake pipe 6 to the level of tank 1, whence it can flow down into radiator core 8.

Although the circuit is designed to be adequate for taking care of the heat dissipating requirements of the engine merely by circulating and cooling water, nevertheless the shunt relation of this circuit to the jacket, the degree of restriction of the shunt communication at 2| when the chamber is employed, and/or the wire netting impedance medium either with or without said constriction, make the cool water supply from the circuit sufficiently inaccessible to the water jacket so that under low load conditions, the flow of cooling fluid from the water jacket to the top tank of the radiator may be mostly steam, which will be condensed partly in said top tank and partly by downiiow into the empty upper part of the radiator core 8; and under heavy load conditions, violent boiling occurs in the cylinder and head jackets. However, a steady state seems to be unusual in normal running of an automobile engine; and I have observed that in practice, instead of a steady outflow of steam from the engine jacket through opening 2! to the short circuit compartment l6 and a correspondingly steady return flow of water, there is usually a more or less violent breathing or pulsating action through the opening 2!. That is to say, due to the depth of the head of the water in these jackets, boiling which occurs under heavy load has a geyser-like functioning, that is to say, water becomes superheated slightabove normal boiling point of 212 and when steam formation commences, the rising bubbles relieve depth pressure and steam-foamed water blows upwardly intermittently, and eventually reaches a higher cooler level where the steam is condensed and collapses resulting in reverse flow of water from the cooling circuit to fill the space voided by collapse of the steam. Consequently, there is a similar tendency to alternating pulsations in uptake pipe 6 so that the proportions of steam or steam bubbles and foam and/or water mingled therewith, may vary widely.

The higher the cooling system is filled above the level of cook 30, the greater the amount of this depth pressure of the water and the more violent will be the alternating blow-out of steam and reverse flow of water.

Incidentally, this explains how excess water in the reservoir 1 and upper ,part of pipe 6, is eventually blown out through the overflow pipe l5, as stated above.

With the above understanding of the fundamental peculiarities of my cooling system, we may now consider the functioning of the wire net medium. A short length of this medium 15 directly in the short circuit-completing path 01' cool water from the supply at lllb to the outlet at Mb; but substantially all of it is in the path of the alternating shunt flow between said short circuit-completing path and the engine jacket. Its mechanical or flow-impeding functions and its heat conducting functions may be considered separately.

Considered as a mechanical flow-impedance medium, it is evident that as concerns flow of cool water through the short circuit-completing path, if and when such flow occurs, its impedance effects are negligible; and they are not important even as concerns slow flow of water through the much longer shunt path; but as concerns my characteristically high velocity flow of steamfoamed water and water propelled by steam, the situation is more complex. While the spheres may be of uniform size and uniformly distributed, the wire netting walls of the spheres afford impedance to high velocity flow which is much greater than the ordinary resistance in the open passages between the exterior surfaces of the spheres. This may be due to surface tension and film tension of the water films formed on the mesh of the netting, through which films the steam, bubbles and foam must break in order to fiow toward the outlet. However, the open passages are crooked, and the higher the velocity flow therein, the more powerfully will inertia operate to drive the fiow against and through the wire netting walls of the spheres, at each bend of the crooked passages. Consequently, though part of the flow transverses the open passages, another quite variable part of it will short cut, as parallel flow through the meshes and interior of each wire net sphere.

As the volume and velocity of the steam or steam-foamed water flowing toward the outlet is much greater than the return-flow of water required to replace that which goes off as steam, it seems evident that the wire mesh medium as a whole tends to afford asymmetric impedance to the alternating flow, one useful effect being that the violence of the out-flow is greatly decreased, while adequate reverse flow of water is not prevented.

The mechanical functions and effects are supplemented by those involving heat-transfer.

Considered as a heat transfer medium, it will be noted that the impedance elements are preferably of copper which is one of the best conductors of heat and so has very great heat absorbing and transferring capacity. Hence it tends to absorb and conduct away heat from steam or steam-foamed water when the fluid is driven toward the outlet, thereby condensing an equiv-alent amount of steam; and to heat the cooler water which reaches it during the reverse flow which follows ejection of the steam from the lower level parts of the jacket. This steam condensing effect also contributes to decrease the violence of the outward, geyser-like pulsations.

As this complex medium extends a very substantial distance in the path of the alternating fiow, it seems to be a fact that in full normal operation, a varying extent of said medium which is first encountered by the steam from the water jacket is always maintained at boiling temperature as described above. On the other hand, it is obvious that another corelative extent of said medium closely adjacent the cool water inlet, is maintained at a much lower temperature, which, in the above described case was 70; and which in any case is low enough to be effectively steamcondensing. Intermediate these two extremes there is a region where effective steam condensation occurs.

From the above consideration of the factors involved, it seems obvious that when the engine is started cold, the gap in the upper part of the cold water circuit prevents circulation. Consequently, all the water in the jacket is quickly raised to boiling temperature and steam begins to rise quietly and becomes condensed in intake pipe 6, then in upper tank 1 and empty upper part of the radiator core. At this time all parts of the impedance medium and possibly the upper part of supply pipe in will be at boiling temperature, but as steam evolution increases its lifting effect combined with that of the pump, starts circulation of water, thereby cooling the part of the impedance medium that is in the short circuit-completing path through the head jacket. But rcmoter parts of the medium remain at boiling, and soon the characteristic cycle of geyser-like pulsations :11

ternating with reverse flow of the cool water become established and the normal functioning will then continue as above described.

A cycle of operationsand functionings, similar in kind though different in degree may be obtained by merely stufling an ordinary head jacket with impedance medium properly designed in accordance with the above principles. Also as disclosed in connection with my application Ser. No. 741,396, an entirely empty chamber and constriction may be designed to insure boiling in the jacket, and development of geyser-like phenomena similar to that above described; and even without the thermostatic valve. But it is obvious that the phenomena described will be much more accentuated and the separation between the cool water region and the boiling water region will be much more closely localized where an impedance medium is employed in combination with a chamber having a properly constricted opening as at 2|.

While I have described in considerable detail the construction and functioning of apreferred form ofimpedance medium, it is to be understood that as stated above, other coarser or finer filling material in various sizes and shapes; may be successfully employed provided it is evenly distributed, contains no very large voids and is constructed and arranged so as to afford ample openings or passages for flow of the fluid, without danger that it will become clogged.

The above described modification and regularizing of the characteristic alternating flow of the water and steam through the impedance medium and constricted opening 2| is of advantage in connection with a heater for the passenger space of the car, such as described in my prior application. By reference to the drawing,-

it will be seen that the heater M is supplied with steam from the rear end of the water jacket through pipe 40, and the condensate therefrom is discharged into thebhamber l6 through'pipe 42. In the prior application, this flow depended entirely upon a pressure differential due to the effect of the constriction 2| on the high velocity outflow of steam, which causes an instantaneous pressure rise in the rear end of the head jacket; and the inertia of the condensed water in the return pipe 42 is relied upon to prevent reverse flow. I have found, however, that when my impedance medium is employed in combination with constriction 2|, it operates to modify the velocity of transmission of pressure to the front end of the jacket and so modifies development of the pressure differential referred to above; and a very important feature of my invention is the interposition of a check valve 42a in the return pipe 42. That is to say, the heat circuit affords a one-way flow path from the head jacket to the chamber [6; and impedance medium improves the circulation in the heating circuit because, as explained above, it affords relatively high impedance to high velocity through-flow of surging steam-foam and bubbling water, thereby increasing the length of time required to transmit the steam expansion impulses between the points of ofitake and return of the heat circuit. As before explained applicant has discovered that real steam cooling as developed in the present apparatus customarily and normally results in intermittent geyser-like up-surging of the steam bubbles, foam and water, alternating with reverse flow of water, and the effect of the impedance medium is to prolong the time required for the high pressure surge to reach the relief region at and near the uptake pipe 5. The result is: that the alternating unequal pressures on the widely separated intake and outlet of the heating circuit are converted into an active one-way flow of steam in said heating circuit, with a further unexpected advant-age that there is live steam and almost no water in the return circuit, clear back to valve-42a. It is of course obvious that the check valve would have the effect of converting the alternating flow into one-way flow, if it were located in the supplypipe 40 instead of in return pipe 42.

While it is possible to have the radiator open to atmosphere through the usual overflow pipe I 5, I prefer an arrangement such as shown in Fig. 1a. In this figure, the top of tank 1 has a filler cap la, on tube lb in which is the upper end of the usual overflow pipe IS. The pipe is sealed in and communicates with the radiator tank only through the opening To, which opening is normally closed by the valve disc Id under pressure of the helical spring 1c. The relief valve disc Id in turn carries a vacuumbreaking valve If which is held by a light coiled spring 1g normally to close the vents H1. in the main valve disc.

With this arrangement, discharge of water displaced by the steam bubbles from the engine jacket will be opposed by the pressure relief valve and a pressure will pile up in the top tank and in the radiator. The pressure relief valve Id may be designed or adjusted for opening at a pressure of, say, four or five pounds, while the vacuum relief valve should open at very slight vacuum, preferably an inch of mercury, or less. I find that even under a full sustained load, with a maximum jacket pressure of pounds, not more than two quarts of water will be expelled from the engine jacket even when initially filled full of water; and by filling it only about half the height of the radiator, there will be no loss of water, under the hardest running.

Although most of the time there will be little or no pressure in the top tank, so that the radiator cap may be removed without danger, there may be times, as when stopping suddenly at top, of a long hill, or where there is an accumulation of air in the tank, with the engine only idling, when removal of the cap might per-' mit a small outrush of hot water or steam. I therefore provide one or more holes, Ix, in the filler tube which will be uncovered and permit a slight outflow of air, steam or water to relieve the pressure and also to give ample warning not to fully remove the cap until the pressure has ceased.

I claim:

engines including low level cylinder jackets supplied with water through a high level head jacket; and a water-cooling circuit including a down-flow air-cooled radiator, an upfiow pipe supplying water to the upper part of the radiator, a return pipe receiving water from the lower part of the radiator and a connection constituting a short circuit-completing path between the outlet of the return pipe and the intake of the upfiow pipe and communicating with the interior of the head jacket to provide a fluidinterchange path for the flow of water and steam between said connection and said head jacket; in combination with a flow-impedance medium interposed in said short circuit-completing path and in said fluid-interchange path, consisting of a multiplicity of hollow wire net bodies.

2. A cooling system for internal combustion engines including low level cylinder jackets supplied with water through a high level head jacket; and a water-cooling circuit including a down-flow air-cooled radiator, an upfiow pipe supplying water to the upper part of the radiator, a return pipe receiving water from the lower part of the radiator and a connection constituting a short circuit-completing path between the outlet of the return pipe and the intake of the upfiow pipe and communicating with the interior of the head jacket to provide a fluidinterchange path for the flow of water and steam between said connection and said head jacket; in combination with a flow-impedance medium interposed in said short circuit-completing path and in said fluid-interchange path, consisting of metal filling material subdivided to afford a multiplicity of reticulations and interspaces without large voids.

3. A cooling system for internal combustion engines including low level cylinder jackets supplied with water through a high level head jacket; and a water-cooling circuit including a down-flow air-cooled radiator, an upfiow pipe supplying water to the upper part of the radiator, a return pipe receiving water from the lower part of the radiator and a connection constituting a short circuit-completing path between the outlet of the return pipe and the intake of the upfiow pipe and communicating with the interior of the head jacket to provide a fluid-interchange path for the flow of water and steam between said connection and said head jacket; and means for restricting flow in said fluid-interchange path including means for positively localizing and restricting the flow section thereof, in combination with a distributed flow-impedance medium consisting of a multiplicity of hollow wire net bodies in the path of flow between the head jacket and said region of restricted flow section.

4. A cooling system for internal combustion engines including low level cylinder jackets supplied with water through a high level head jacket; and a water-cooling circuit including a down-flow air-cooled radiator, an upflow pipe supplying water to the upper part of the radiator, a return pipe receiving water from the lower part of the radiator and a connection constituting a short circuit-completing path between the outlet of the return pipe and the intake of the upfiow pipe and communicating with the interior of the head jacket to provide a fluid-interchange path for the flow of water and steam between said connection and said head jacket; and means for restricting flow in said fluid-interchange path including means for positively localizing and restricting the flow section thereof, in combination with a distributed flow-impedance medium consisting of a multiplicity of hollow wire net bodies in the path of flow between the head jacket and said region of restricted flow section and also between said region and the intake of the upfiow pipe.

5. A cooling system for internal combustion engines including low level cylinder jackets supplied with water through a high level head jacket; and'a water-cooling circuit including a down-flow air-cooled radiator, an upfiow pipe supplying water to the upper part of the radiator, av return .pipe receiving; water from the lower part of the radiator and a connection constituting a short circuit-completing path between the outlet of the return pipe and the intake or the upfiow pipe and communicating with the interior of the head jacket to provide a fluid-interchange path for the flow of water and steam between said connection and said head jacket; and a pump to assist water circulation in said circuit in combination with means for restricting flow in said fluid-interchange path including a distributed flow impedance medium consisting of a multiplicity of hollow wire net bodies.

6. A cooling system for internal combustion engines including low level cylinder jackets supplied with water through a high level head jacket; and a water-cooling circuit including a down-flow air-cooled radiator, an upfiow pipe supplying water to the upper part or the radiator, a return pipe receiving water from the lower part of the radiator and a connection constituting a short circuit-completing path between the outlet of the return pipe and the intake of the upfiow pipe and communicating with the interior of the head jacket to provide a fluid-interchange path for the flow of water and steam between said connection and said head jacket; and a pump to assist water circulation in said circuit; in combination with means tor restricting flow in said fluid-interchange path including a distributed flow impedance medium consisting of metal filling material subdivided to afiord a multiplicity of reticulations and interspaces without large voids.

7. A cooling system for internal combustion engines including low level cylinder jackets supplied with water through a high level head jacket; and a water-cooling circuit including a down-flow air-cooled radiator, an upfiow pipe supplying water to the upper part of the radiator, a return pipe receiving water from the lower part of the radiator and a connection constituting a short circuit-completing path between the outlet of the return pipe and the intake of the upfiow pipe and communicating with the interior of the head jacket to provide a fluid-interchange path for the flow of water and steam between said connection and said head jacket; and a pump to assist water circulation in said circuit; in combination with means for restricting flow in said fluid-interchange path including a distributed flow impedance medium consisting of separate contacting elastic units made of copper netting.

8. A cooling system for internal combustion engines including low level cylinder jackets supplied with water through a high level head jacket; and a water-cooling circuit including a down-flow air-cooled radiator, an upfiow pipe supplying water to the upper part of the radiator, a return pipe receiving water from the lower part of the radiator and a connection constituting a short circuit-completing path between the outlet of the return pipe and the intake of the upfiow pipe and communicating with the interior of the head jacket to provide a fluid-interchange path for the flow of water and steam between said connection and said head jacket; and a pump to assist water circulation in said circuit; in combination with means for restricting flow in said fluid-interchange path including a distributed flow impedance medium of wire net in the form or small hollow shells.

9. A cooling system for internal combustion engines including low level cylinder jackets supplied with water through a high level head Jacket; and a water-cooling circuit including a downflow air-cooled radiator, an upfiow pipe supplying water to the upper part of the radiator, a return pipe receiving water from the lower part of the radiator and a connection constituting a short circuit-completing path between the outlet of the return pipe and the intake of the upflow pipe and communicating with the interior of the head jacket to provide a fluid-interchange path for the fiow of water and steam between said connection and said head jacket; and a pump to assist water circulation in said circuit; in combination with means for restricting flow in said fluid-interchange path including a distributed flow impedance medium consisting of separate contacting elastic units made of copper netting in the path of flow between the head jacket and said region of restricted flow section and also between said region and the intake of the upflow pipe. 10. A cooling system for internal combustion engines including low level cylinder jackets supplied with water through a high level head jacket; a cooling circuit including a down-flow air-cooled radiator, an upflow pipe leading to the upper part of the radiator and a centrifugal pump to assist the upflow of water in said upflow pipe, a return pipe receiving water from the lower part of the radiator and a connection constituting a short circuit-completing path between the outlet of the return pipe and the intake of the pump and communicating with the interior of the head jacket to provide a fluid-interchange path for the flow of water and steam between said connection and said head jacket; in combination with a distributed flow-impedance medium interposed in said fluid-interchange path consisting of wire net filling material formed and arranged so as to afiord distributed flow resistance which is small for low velocity flow of water but great for high velocity flow of water and steam; and which is a good conductor of heat, operating to absorb heat and condense steam when and where the flow is from the jacket and to heat water when and where the flow is reversed.

11. A cooling system for internal combustion engines including low level cylinder jackets supplied with water through a high level head jacket; a cooling circuit including a down-flow, air-cooled radiator, an upflow pipe leading to the upper part of the radiator and a centrifugal pump to assist the upflow of water in said upflow pipe, a return pipe receiving water from the lower part' of the radiator and a connection constituting a short circuit-completing path between the outlet of the return pipe and the intake of the pump and communicating with the interior of the head jacket to provide a fluid-interchange path for the flow of water and steam between said connection and said head jacket; in combination with a distributed flow-impedance medium interposed in said fluid-interchange path consisting of filling material whichis subdivided and reticulated so as to afiord distributed flow resistance which is small for low velocity flow of water but great for high velocity flow of water and steam; and which is a good conductor of heat, operating to absorb heat and condense steam when and where the flow is from the jacket and to heat water when and where the flow is reversed.

12. A cooling system for internal combustion engines including a water jacket for the engine, a cooling circuit serially including a down-flow, air-cooled radiator; means associating said cooling circuit with the water jacket, including a chamber providing a short circuit-completing part of the cooling circuit and which communi- Y tions, including reticulated, hollow copper bodies elastically packed in said chamber, and in a region extending a substantial distance outside the restricted flow paths through which said chamber communicates with said jacket, all designed and operating to ensure boiling in said engine jacket.

13. A cooling system for interal combustion engines including a water jacket for the engine, a cooling circuit serially including a down-flow, air-cooled radiator; means associating s'aid cooling circuit with the water jacket, including a chamber providing a short circuit-completing part of the cooling circuit and which communicates with the upper part of the engine jacket only through restricted flow paths; and means for controlling high velocity flow of fluid to and.

- plied with water through a high level head jacket; and a cooling circuit therefor including a down-flow air-cooled radiator, an upflow pipe supplying water to the upper part of the radiator, a return pipe receiving water from the lower part of the radiator and a connection con- 1 stituting a short circuit-completing path between the outlet of the return pipe and the intake of the upflow pipe and communicating with the interior of the head jacket to provide a fluid-interchange path for the flow of water and steam between said connection and said head jacket; and flow-restricting means interposed in said fluidinterchange path, said means including a multiplicity of hollow wire net bodies, all designed and arranged to ensure boiling in said jackets; in combination with a car heater and circuit therefor, including a steam intake pipe connected to an upper part of the head jacket on the head jacket side of said flow restricting means and a return pipe discharging into the cooling circuit, on the opposite side of said flow restricting means.

I 15. A cooling system for internal combustion engines including low level cylinder jackets supplied with water through a high level head jacket; and a cooling circuit therefor including a down-flow, air-cooled radiator, an upflow pipe supplying water to the upper part of the radiator,

all designed and arranged to ensure boiling in said jackets; in combination with a car heater and circuit therefor, including a steam intake pipe connected to an upper part of the head jackat on the head jacket side of said fiow restricting means and a return pipe discharging into the cooling circuit, on the opposite side of said flowrestricting means; and a check valve in said circuit to check reverse flow of fluid therein.

16. A cooling system for internal combustion engines including low level cylinderjackets supplied with water through a high level head jacket; a cooling circuit including a down-flow, aircooled radiator, an upfiow pipe leading to'the upper part of the radiator and a centrifugal pump to assist the upfiow of water in said upflow pipe, a return pipe receiving water from the lower part of the radiator and a connection constituting a short circuit-completing path between the outlet of the return pipe and the intake of the pump and communicating with the interior of the head jacket to provide a fluid-interchange path for the flow of water and steam between said connection and said head jacket; and flow restricting means in said fluid-interchange path including wire net filling material formed and arranged so as to aiford distributed flow resistance which is small for low velocity flow of water but great for high velocity flow of Water and steam; and which is a good conductor of heat, operating to absorb heat and condense steam when and where the fiowis from the jack et and to heat water when and where the flow is reversed; all designed and arranged to ensure boiling in said jackets; in combination with a car heater and circuit therefor, including a steam intake pipe connected to an upper part of the head jacket on the head jacket side of said flow restricting means and a return pipe discharging into the cooling circuit, on the opposite side of said flow-restricting means, and a check valve in said circuit to check reverse flow of fluid therein.

1'7. A cooling system for internal combustion engines, including a head jacket for the engine, a cooling circuit; means associating said cooling circuit with the head jacket, including a chamber providing a short circuit-completing part of the cooling circuit and which communicates with the head jacket only through restricted flow paths;

in combination with a car heater and circuit therefor, including a steam intake pipe connected to'an upper part of the head jacket on the head jacket side of said restricted flow paths, and a return pipe discharging into the cooling circuit, on the opposite side of said flow-restricting means; and a check valve in said car heater circuit to check reverse flow of fluid therein.

18. A cooling system for internal combustion engines, including a head jacket for the engine, a cooling circuit; means associating said cooling circuit with the head jacket, including a chamber providing a short circuit-completing part of the cooling circuit and which communicates with the head jacket only through restricted flow paths; in combination with a car heater and circuit therefor, including a steam intake pipe connected to an upper part of the head jacket on the head jacket side of said restricted flow paths, and a return pipe discharging into the cooling circuit, on the opposite side of said flow-restricting means; and a check valve in said return pipe, to prevent reverse flow toward the car heater.

19. A cooling system for internal combustion engines, including a water jacket for the engine, a, cooling circuit including a downflow, air-cooled radiator having a core extending above the top and below the bottom of the jacket, an upflow pipe supplying water to the upper part of the radiator, a return pipe receiving water from the lower part of the radiator and a pump to assist water circulation through said radiator; means associating said cooling circuit with the water jacket, including a chamber providing a short circuit-completing part of said circuit and which communicates with the upper part of the jacket only through restricted flow paths; all designed and operating to insure boiling and steam evolution in the water jacket: in combination with a car heater having its steam inlet connected to the upper part of the jacket, and a return pipe connected to said chamber.

20. A cooling system for internal combustion engines, including a water jacket for the engine, a cooling circuit; means associating said cooling circuit with the water jacket, including a chamber providing a short circuit-completing part of said circuit and which communicates with the upper part of the engine jacket only through restricted flow paths; in combination with a, car heater having a steam inlet connected to the engine jacket and a return pipe discharging into said chamber.

SAMUEL W RUSHMORE.

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