US2798361A - Internal combustion engines - Google Patents

Description

July 9, 1957 F. A. .HIERSCH 2,798,361

INTERNAL COMBUSTION ENGINES Original Filed Aug. 19, 1947 5 Sheets-Sheet l S Q E "III/IIIIIIIIIIII/II III/IIIIIIIIIIIIIIIIIIIIIIA! INVEN TOR.

FRtfDER/GK A. HIERSOH ATTORNEYS.

July 9, 1957 F. A. HIERSCH 2,798,361

INTERNAL COMBUSTION ENGINES Original Filed Aug. 19, 1947 3 Sheets-Sheet 2 O m l INVENTOR.

FEEDER/0K A. HIERSGH ATTORNEYS July 9, 1 957 F. A. HIERSCH INTERNAL COMBUSTION ENGINES 5 Sheets-Sheet 3 Original Filed Aug. 19, 1947 IN VEN TOR. FREDERICK A HIE RSOH A T TORNE Y5.

United States Patent i INTERNAL (IONEUSTION ENGINES Frederick A. Hiersch, Detroit, Mich, assignor to Continental Aviation and Engineering Corporation, Detroit, Mich, a corporation of Virginia Original application August 19, 1947, Serial No. 769,813. Divided and this application July 6, 1953, Serial No.

2 Claims.- (Cl. oil-35.6)

This invention relates to an internal combustion engine of the ram jet type, and especially to a fuel preheater for such an engine.

For maximum efficiency, a power plant should be designed to minimize heat losses. Heat exchangers are a common expedient to that end. It is desirable that aircraft be made as light as possible without sacrificing strength.

It is an object of this invention to provide a ram jet engine in which a heat exchanger is so located as to minimize heat losses. In some embodiments of the invention, the heat exchanger is so designed as to add to the structural strength and rigidity of the engine housing.

In the drawings:

Fig. 1 is a longitudinal sectional view through a jet engine embodying the invention.

Fig. 2 shows the helically wound storage tank of the engine of Fig. 1, but in Fig. 2 the storage tank is shown as a straight tube, for the purposes of explaining its function.

Fig. 3 shows another embodiment of the invention, being a developed View of another form of heat exchanger.

Fig. 4 is a view in section on line 4-4 of Fig. 3.

' Fig. 5 is an enlarged detail view of the embodiment shown in Fig. 3, illustrating a modification of this embodiment.

Fig. 6 is a view in section substantially on line 66 of Fig. 5.

Fig. 7 is a view in section substantially on line 7--7 of Fig. 5.

Fig. 8 is a perspective view showing still another embodiment of a heat exchanger made according to the invention.

Fig. 9 is a view in section substantially on line 99 of Fig. 8.

Fig. 10 is a developed view, with the outer wall removed, of the heat exchanger shown in Fig. 8, and

Fig. 11 is a view in section on line 11-11 of Fig. 10.

This is a divisional case of my copending application Serial No. 769,813, filed August 19, 1947, for Internal Combustion Engine, now abandoned.

Fig. 1 shows a ram jet engine made according to the invention, substantially in its entirety. As can readily be seen from Fig. 1, the engine comprises a multiple walled housing 2. In the forward end of the housing 2 there is a difiuser section 4 formed by the inside of housing 2 and inner body 6. Approximately amidships there is a combustion chamber section 8 which extends rearward to a point near the nozzle 10 at the end of the housing.

The nozzle 10 at the tail end of the engine is fitted with a plug 12 which is movable axially of the housing to vary the nozzle diameter. Plug 12 consists of a hollow bulbous body 14. A cavity 16 is formed by the wall of body 14 and an end cap 18. The body 14 is preferably made of a porous metal such as porous chrome metal made by the baking soda process having wide use for seat cooling and which permits a known rate of gas ice leakage therethrough. The plug 12 is hydrogen cooled, hydrogen being admitted through the passage 20 from a hydrogen tank 22 located in the inner body 6. Suitable control means 24 are also preferably located in the inner body 6, and serve to control the functioning of the jet engine.

The forward end of the engine houses a fuel tank 26 which is preferably helically wound into a coil located between the two walls of the multiple walled housing. This housing consists of an outer Wall 28 and an inner wall 30. In the preferred form, the fuel tank 26 is maintained under pressure, hydrogen from the tank 22 being utilized for this purpose. As can best be seen in Fig. 2, the fuel tank is provided with a take off tube 32 which communicates with a tube 34 which is substantially coextensive with the fuel storage tank. Tube 34 is provided with valves 36 at numerous stations throughout its length. In Fig. 2, valves 36 are shown only at the extreme ends of the tube 34, but it will be understood by those skilled in the art that other valves may be disposed at one or more stations between the ends.

Valves 36 are shown only diagrammatically in Fig. 2, inasmuch as they do notthemselves constitute the invention in this case. Valves 36 may be any suitable valve which is sensitiveto the presence of liquid, as for example, a solenoid operated valve which is electrically actuated to be open when the valve is surrounded by vapor. Numerous valves suitable for this purpose are available, and the details thereof need not be set forth here. The object of the tube 34 is to permit liquid to be drawn off through the outlet 32 at all times, regardless of the location of liquid in the tank.

Liquid which is withdrawn from the fuel tank through the outlet 32 is delivered to an annular header 38 which is located amidships adjacent the fuel storage tanks. Tubes 40 communicate at one end with header 38. These tubes 40 extend rearward from header 38 in a helix which is wound in the right hand direction to a point or plane 42 near the tail of the engine. From this point, the tubes bend forward and wind in a left hand helix toward the header 44, to which they return the fuel. Fuel passes from header 44 to nozzles, not shown, which feed the fuel to the combustion chamber.

Thus we have the tube halves 46 forming a right hand helix, and the tube halves 48 forming a left hand helix. The right hand helix overlies the left hand helix, and both halves lie in the annular space formed by the inner and outer walls 28 and 30 respectively of the multiple walled housing. It will be further noted by those skilled in the art that both halves of the tube 40 lie in the annular space of that. portion of the housing which envelopes the combustion chamber 8.

The individual tube type heat exchanger shown in the embodiment of Fig. 1 will be found preferably where high pressures are used in the system-pressures where the order of magnitude is 1200 p. s. i. Where lower pressures are used, a preferred type of heat exchanger is one which is made so that the fuel conduits add to the structural strength and rigidity of the housing. Two embodiments of heat exchangers made in this manner are shown in Figs. 3-11 inclusive.

In Figs. 3-7 inclusive there is shown one embodiment of this type of heat exchanger. Considering now Figs. 3 and 4, the inner wall 30 and the outer wall 28 of the multiple walled housing are much the same as in the first embodiment. In addition there is an intermediate wall 50 disposed between walls 28 and 30. The beads 52 form concave grooves which, in conjunction with the inner wall 30, provide flow passages for liquid fuel. The intermediate Wall 50 is preferably seam welded to the inner wall 30 as shown at 53. As will be understood by those skilled 3 in the art, walls 30 and 50 will be seam welded between adjacent beads 52.

The embodiment shown in Fig. 3 may be modified as shown in Figs. 5-7:bythe addition of bridges 54 whereit is,desired to substantially eliminatethe mixing ofliquid of intersecting beads orpassag'es 52; Each bridge 54 comprises end portions .adapted to substantially fill the fuel flow passages, and a reduced diameter intermediate portion which is adapted to cross an intersecting fuel passage to permit the passage of fuel in one direction through the reduced diameter portion, and in the other direction around the reduced diameter portion. T

It will be understood by those skilled .in the artthat Figs. 3-7 inclusive are developed views, and that the 9 actual embodiment of the heat exchanger is cylindrical rather than plane.

' Referring now in detail to Figs. 8-11 inclusive, the outer and inner walls 28 and 30 are shown much the same as before, with an intermediate wall 56 between walls 28 and 30 and spaced from both of them. Intermediate wall 56 is turned inwardly at both ends and is secured as by welding to inner wall 38 as shown at 58. Intermediate wall 56 is dimpled inward as shown at 60 to space it from the inner wall 30. Intermediate wall 56 is furthermore beaded in a zigzag pattern, the beads being deformed outwardly as shown at 62, and contacting the outer wall 28. Between the Vs of the zigzag beads, intermediate wall 56 is slotted to form fuel passages '64. A fuel inlet 66 communicates with one end of the heat exchanger, and a fuel outlet 68 communicates with the other end of the heat exchanger by means of a duct 70 which is provided between walls 30 and 56. See especially Figs. and 11.

Operation Referring now to the'embodiment shown-in Fig. 1, fuel is admitted to header 38, whence it flows through the right hand helix half 46 of tubes 40 rearward, returning through the left hand helix 48 to the header 44. As fuel flows through the tubes 40 it is heated up by the heat escaping from the combustion chamber. The heat exchanger thus serves the purpose of cooling the walls of the combustion chamber, at the same time that it absorbs heat which might otherwise be lost and turns the heat into useful heat by preheating the fuel before it reaches the nozzles.

In the embodiment shown in Figs. 37 inclusive, fuel flows through the passages provided by beads 52, accomplishing the same objects as set forth above in connection with Fig. 1. Where the system is provided with bridges as shown in Figs. 5, 6 and 7, fuel flows inone direction through the right hand wound fuel passages, and flows in the other direction through the left hand wound passages. The bridges 54 need not be absolutely fluid type, inasmuch as liquid fuel is present in both passages.

In the embodiment shown in Figs. 8-11 inclusive, fuel flows into the heat exchanger by way of inlet 66'flowing to the right as seen in Fig. 10, between the converging beads 62, whence it flows radially through passages 64 into the space between walls 30 and 56. From this space it flows radially outward again through other passages 64 into the space between beads 62 which diverge toward the right as seen in Fig. 10, and leaves the heat exchanger by way of duct and outlet 68.

It will be understood that the heat exchanger embodiment shown in Figs. 3-11 inclusive presents a stronger and more rigid engine housing than the tube type shown in Fig. 1. To the end that the tube typeheat exchanger of Fig. 1 may be made more rigid, the heat exchanger may if desired be provided with a header or a pair of headers at the rearmost end 42. This modification is not shown, but will be readily understood by those skilled in the art.

I claim:

1. In a jet engine, a double-walled housing comprising concentric elongated tubular sections disposed in spaced relation to define an annular space, a pair of concentric outer and inner annular headers in said annular space at the mid-section of said engine arranged in contacting supporting relation with said concentric elongated tubular sections, a combustion chamber within the housing and disposed within the rear portion of the engine rearwardly of said headers, a coiled fuel storage tank ahead of said headers and disposed in said annular space in contacting relation with said tubular sections to support same one from the other, an intermediate tubular section fitted into said annular space enveloping the combustion chamber and providing a rigid support for said outer and inner tubular sections, said intermediate tubularsection provided with intersecting channels through which fuel may be circulated in heat exchange relation with said combustion chamber and connected respectively with the outer and inner headers to receive fuel from said outer header and to discharge the preheated fuel to said inner header, and means discharging said preheated fuel from said inner header to said combustion chamber.

2. ha jet engine, a double-walled housing structure comprising concentric elongated tubular sections disposed in spaced relation to define an annular space, a pair of concentric outer and inner annular headers in'said annular space at substantially the mid section of said engine, a combustion chamber within the housing and disposed within the rear portion of said engine, a fuel storage tank between the two housing walls in the forward portion of the engine and connected with said outer header, and a fuel preheater between the two housing walls and encompassing the said combustion chamber, said preheater comprising a fabricated structure contacting both said concentric tubular sections and providing intersecting conduit portions extending longitudinally of said housing structure communicating in series with said outer end inner headers, and tubular bridge structure at said intersection of said conduit portions to provide cross-over passage for said fuel flow and means discharging said preheated fuel from said inner header to said combustion chamber.

. References Cited in the file of this patent UNITED STATES PATENTS 1,601,637 Meigs Sept. 28, 1926 2,338,090 Bradfield Ian. 4, 1944 2,438,247 Knudsen Mar. 23, 1948 2,469,828 Johnson May 10, 1949 2,540,594 Price Feb. 6, 1951

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