US2587801A - Oil cooler - Google Patents

Description

March 4, 1952 J. E. WOODS OIL COOLER 4 Sheets-Sheet 2 Filed July 6, 1945 HM m d W 0 O W W Ur m o f 0 2 n 2 o 5 2 6 2 a f 3 Z 1 2 8 d a 1 a 0 Y 6 1 J B i 4 a 6 o owc o 0 0 o wwo o 2 (0 00 v 0 0 0 0 m 5 4 000 00u0u0 (c.000 o ,0 0 0 0 0m0u0 0m0wo 0m0w0 0 o 3 0 0 0 0 0m0 0 0 0 0 0 0 0 o 000 00 000 0 00 000 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 ,0 0 0 0 m0 mmwow 0 0w M0 0 0 0w 0 o moowo omomw m m)wm 0 w 0 0 w wwww 0 0w0w0 cno 0w0wo ommwo 0 o 0 0 0 0 90 0 0 0 0 0 0 0. o 0 0 0 0 0m0 0 0 0 0 m 0 0- im mwmmw mwmww W j 2 @m 0 0m 0 0 1 0 o m M #4 f March 4, 1952 w s 2,587,801

OIL COOLER Filed July 6, 1945 4 Sheets-Sheet 3 IN V EN TOR.

Y (/0411 Mac/J J. E. WOODS March 4, 1952 OIL COOLER 4 Sheets-Sheet 4' Filed July 6, 1945 INVENTOR.

Job? 5. Wow 6 Patented Mar. 4, 1952 OIL COOLER John E. Woods, Cohasset, Mass., assignor, by

mesne assignments, to Standard-Thomson Corporation, Boston, Mas

s., a corporation of Dela- Application July 6, 1945, Serial No. 603,491

3 Claims. 1

The present invention relates to oil coolers and more particularly to oil coolers having thin wall closely spaced tubes, particularly useful for aircraft.

One of the usual forms of oil coolers employs closely spaced thin wall tubes which are provided with hexed ends, the ends of the tubes being soldered to provide a unitary core. Suitable baffies are included within the assembly by attachment between rows of tubes. The entire assembly is mounted in a tank or shell. Another form of cooler is of the general type illustrated in my Patent #2298396 dated October 13, 1942, in which copper or aluminum tubes are mounted in headers and suitably secured thereto.

Ineither form of cooler considerable difiiculty has been experienced because of the collection of sludge in the spaces between the tubes and particularly at points adjacent to the edges of the baflles. Furthermore, the sludge may contain small chips or grains of metal which have come all parts of theengine and circulated in the oil stream. To the extent that the oil cooler collects these chips, it afiords protection to the engine.

It has been found, however, that when an oil it which will circulate back to the engine as above described.

Theobject of the present invention is to provide an oil cooler of the type embodying closely spaced thin wall tubes in which the core may be removed from the jacket and the baflies removed from the core, whereby a thorough and effective cleaning operation may be readily performed.

With this object in view the present invention comprises either a header type or headerless type core in which longitudinal or axial flow baffles are used. The construction is such that the baflfles may be easily removed and replaced while being effectively sealed within the cooler during normal operation so that proper oil flows will occur. The tank or jacket is secured to the headers in such a manner that it can be readily removed. The in- .nershell of the tank is arranged to engage the 2 edges of the bafiles and seal them against channeling of the fluid around the tubes.

In the accompanying drawings; Fig. 1 is a sectional view of a core for an oil cooler according to therpresent invention; Fig. 2 is an elevation of the complete oil cooler, with some parts shown in section; Fig. 3 is an elevation of oneof the removable baffles; Fig. 4 is a section on line 44 of Fig. 3; and Fig. 5 is an end view of the completed cooler with a portion shown in section; Fig. 6 is an end view of a headerless type oil cooler according to the present invention; Fig. '7 is an enlarged detail view of .a portion of the cooler shown in Fig. 6; Figs. 8. and 9 are sectional views on lines 8--3 and 9-9 respectively of Fig. '7; Fig. 10 is a section on line l0-l0 of Fig. 6; and Fig. 11 is an end view of a headerless core of a modifled form.

The construction shown in Fig. 1 of the present invention comprises a core consisting of a large number of closely spaced thin wall tubes it protruding at opposite ends through header plates l2 each of which is provided with an outwardly extending circumferential flange l4. To illustrate the. size and spacing of the tubes, each tube may be of the order of .268" in diameter and the tubes may be spaced .313" on centers. The tubes may have a wall thickness of about .005. The tubes are usually of copper or aluminum.

Thetubes after being mounted in the headers may have their ends expanded as described by my patent or as herein shown may be left with round ends. Preferably the tube ends are brazed to the headers by the method fully described in my co-pending application Serial No. 46 ,109, filed October 7, 1942, now Patent No. 2,389,175.

As shown in Figs. 1 and 5, the tubes are arranged in groups. Between adjacent groups, there is a. space I 6 of about .085 for accommodatiion of the bafiles. Five such spaces are provided in the cooler shown inthe drawing, whereby the oil is caused to flow through six axial-flow passages. For simplicity, not all of the tubes are shown in the drawing but a completed cooler may comprise about 3600 tubes.

The core is baffled for axial flow by baffles l8 inserted in the spaces I6. As shown in Figs. 3 and 4, each baille comprises a sheet of the same material as thetubes, that is. aluminum or copper, about .025 thick. Each bafile is provided with pressed spacer projections 2il,'protruding in both directions from the sheet to engage with tubes on opposite sides, so that the baffle is positioned in the inter-tube space. Each baille is header.

of a width to extend across a chord of the core. At the sides each baffle is provided with wings 22 preferably brazed or welded thereto. The wings are of thinner material (say .016 in thickness) so that they can be readily bent for a purpose to be later described. The wings are of a length approximately equal to or slightly less than the height of the core between headers. The bafiles are of less height than the wings to provide an oil fiow space 24. One edge of each bafile is adapted to be sealed against one of the headers, and the space 24 provides an inter-pass oil flow passage.

The sealed ed e of each baflie is provided with a sealing strip 26 of a rubber-like compound such as neoprene. As shown in Fig. 4, each strip comprises a double channel. The edge of the bafile is inserted into one of the channels and the bafile is firmly cemented thereto by any suitable compound. After the bafiles have been assembled as above described in proper widths de ending on the lengths of. the several chords l6, they are inserted into the core in the manner illustrated in Fig. 1. Successive bafiles are inverted, that is one'bafile has its sealing strip 26 against one header, the next baiile has its sealing strip against the opposite header and so on, whereby a tortuous series of axial oil-flow passes is formed, as indicated by the arrows in Fig. 2. The lengths of vthe wings 22 are such that the bafiie may be readi y inserted upon pressure a plied in a manner to f ex the sealing strip 26 into tight engagement with its adjacent header. Sealing of the strip against the header is effected by the pressure of the ends of the wings 22 against the opposite Sufficient sealing pressure may be obtained to prevent leakage while still allowing for easy insertion or removal of a baffle.

After insertion. of the baflles the wings 22 protrude somewhat beyond the edges of the flanges [4. The Wings are then bent over slightly as shown in Fig. l but with their edges still protruding slightly beyond the flanges. As will. be

shown later, the construction requires that certain small spaces exist outside the outer tubes and these spaces are filled to prevent channeling I between the outer tubes and the shell. The filling are preferably of a soft material in order that they may be easily crushed to fill the spaces.

The tank comprises a cylindrical inner shell 30 and an outer shell or jacket 32 suitably secured I thereto. The jacket is provided with a casting 34 arranged to receive the usual control valve assembly. The casting is formed with an inlet openg at and a by-pass outlet openin 38. both of which communicate directly with the space between the inner shell and the jacket, and an outlet opening 43 which communicates with the core. The inner shell is provided with a rectangular opening 42 which is near the top of the jacket and substantially opposite the outlet 40.

The inside diameter of the shell 30 is such as toslip over the flanges i l of the headers. The shell is started over one header and the wings 22 are ofiset inwardly to allow the shell to pass over them. The shell is then pushed down until its 22 so that after application of the shell they fit tightly against its inner surface and prevent leakage of oil around the core. It will be observed that the wings should be bent in such a direction that the oil pressure tends to force them against the shell.

The tank is preferably secured to the header flanges in the following manner. Each flange I4 is provided with a large number of bosses M welded or brazed to the inner surface of each flange. Each boss is tapped to receive a bolt 45. A gasket 48 having openings. to receivethe bolts is placed thereon with its sealing surface extendin over the joint betweenthe flange and the shell 3. A metal locking plate 50 of substantially the same shape as the gasket is then placed on the bolts. The same assembly is provided at each end of the cooler. The locking plates are secured and the gaskets are compressed by nuts 52 by which sufficient pressure may be applied to form a leak-proof joint. Suitable lock washers may be used under the nuts in accordance with the usual practice. The bosses prevent the use of active tubes out to the extreme edg of the header, and

for that reason the stuffing tubes 28, which have been previously described, are used.

The space between the inner shell 33 and the jacket 32 is baffled to provide proper oil flows under both normal and warm-up conditions. The particular baffling will be obvious to those skilled in this art and forms no part of the present invention, and is therefore not herein described in detail. The oil flows will now be briefly described..-

Under normal conditions the oil enters the inlet 36. The by-pass outlet 33 is closed by the control valve. The oil flows around the jacket and is directed by the jacket bafiling into the rectangular opening 42 through which it passes into the core. The oil then passes along the first pass of tubes then through the free space 24 below the first bafile' then along the second group of tubes, then over theiree space 24 above the second baffle, andso on until it reaches the outlet 40. Under warm-up conditions, the oil may be congealed in the inter-tube space of the core, and the by-pass outlet 38 is then opened. Oil fiows through the inlet 36 into the space between the shell and jacket. It completely fills that space and news around it to the Warm-up outlet 38. This How of warm oil through the jacket serves to thaw out the congealed oil within the cooler. When normal conditions are resumed, the oil flows through the several passages of the core as described above.

With respect to the seal between the sealing strips and the headers, no sealing compound has been found necessary. Under the compression of the sealing strip 26 caused by forcing the wings 22 into the space between the headers, the strip edges are flush with the outer edges of the header flanges. There is sufilcient resiliency in the wings is forced into tight contact with the header. Under conditions of hot oil flow in normal use of the cooler the strips may secure themselves to the headers by a process analagous to vulcanization.

After the cooler has been in use for sufficient time to require cleaning, it is readily dismounted for that purpose. By removing the gasket assembly at both ends, the tank is easily slipped off the core. The bafiles may then be removed by straightening the wings. By gripping one wing. each baflle may be simply drawn out. If the seals strip has vulcanized to the header, the baflle can nevertheless be removed although the strip will necessarily become torn. The pieces of the strip which remain attached to the header may be easily removed with a long 'hook-shaped'imflushing operation may be performed.

plement. The core is then flushed out by forcing any suitable cleaningcompound such as trichlorethylene or gasoline through the inter-tube spaces. Since the flow of cleaning fluid is not in any way impeded by the bafiies, a thorough The sludge tends to collect at the places where the tubes and bafiles jointhe headers and if the baffles were in place it would be difiicult for the cleaning fluid to gain access thereto with sufiicient scouring action to remove the accumulation. With the baflles out, however, no difficulty is experienced. After cleaning the core, the baf fies and tank may be reassembled so that the coolern ay be restored to use.

The features of the present invention are applicable to headerless type coolers which are shown in Figs. 6 to 11. The construction shown in Figs. 6 to comprises an oil cooler employing hexed tubes of standard construction throughout and the construction shown in Fig. 11 is a modified form utilizing tubes of special end construction.

Referring to the modification shown in Figs. 6 to 10, this comprises a bundle of tubes 56 each provided with hexagonal end portions 58 according to usual tube construction. The tubes are arranged in a bundle of the desired core shape with the edges of the hexed end portions in contact to form the usual honeycomb arrangement. At the places at which baffles are to be inserted, corrugated spacing strips 63 are inserted into the bundle. Only one strip 68 is shown in Fig. 6 but it will be understood that live such strips of proper length will be used if the oil flows are to be similar to those in the construction of Figs. 1 to 5. The strips are of a height equal to that of the hexed end portions of the tubes, as shown in Figs. 8 and 9, and are corrugated as shown in Fig. '7 to conform to the end portions of the tubes.

The entire bundle of tubes and spacing strips is secured together by dipping the ends in solder in accordance with usual methods of manufacturing headerless heat exchangers.

The baffles which are inserted in the core are identical with those shown in Figs. 3 and 4 and are indicated at I8 in Figs. '7, 8 and 9. Each baffie is provided at one side with a sealing strip 62 of flexible material. These sealing strips are similar to the strips 26 of the baffles previously described but as shown in Figs. 8 and 9 preferably have elongated end portions 6a to conform to the tortuous passage in which the baffles are received. The baffles are provided with wings 22 exactly as in Fig. 3 in order to space the baf fies properly within the unit and to seal against the inner shell in the same manner as in the header type.

As shown in Figs. '7, 8 and 9 the width of the spacing strip 60 is such that the flat baflie I8 may be inserted with adequate clearance between the baffle and the tubes. The ends of the sealing strips 64 seat against the spacing strip 66 but, as will be apparent from the construction, the sealing strip is necessarily distorted to establish a seal at all points along the length of the corrugated spacer. Thus, in Fig. 8 the baflle lies symmetrically between the tubes whereas in Fig. 9 the baffle is closely adjacent to one of the tubes and the ends of the sealing member are necessarily distorted sidewise. Although the sealing strip is thus distorted, the bafiie itself and one of the wings 22 are capable of clear passage through the core.

In the construction of headerless type units,

it is customary to'rsol'der the shell direct to the hexed ends of the outside tubes. In order to provide for demountability, according to the present invention, a ring 66 is secured at each end of the core. The tank 68 which has an inner shell portion 10 is slipped over the rings 66. The wing portions 22 of the'bafiles engage the inner shell H3 in the same manner in which they engage the inner shell 30 of the header type construction previously described. Each ring 66 is: inwardly bulged as indicated at 12 to afford space for a flexible gasket 14. After assembly the shell 10 is secured to the rings 12 by means of nut and bolt connections lfi shown in Figs. 6 and 10. This construction permits removal of the tank and bafiies in a manner similar to that described for the header type. Upon removal of the bolts the tank is drawn off. Then the baffles may be drawn out so that the core may be cleaned, after which the baffles may be reinserted and the tank may be again applied.

The construction shown in Fig. 11 is also a headerless type construction and avoids the use of acorrugated spacer strip although it requires several rowsof special tubes. As in Fig. 6 only one spacing strip is shown. This is indicated at 18 and comprises a fiat strip. On opposite sides of the strip there is a row of special tubes havingpentagonal end portions, which may be soldered directly to the spacing strip. As in constructions previously described, several of these strips, preferably five, are used, the strips being disposed in the baffle positions indicated in Fig. 1. Baflles identical with those shown in Figs. 3 and 4 may be used. The sealing strips seat alternately at opposite ends of the core against the spacing strips 18. The spacing strips are of a thickness to accommodate the bailie and, since they are flat and allow a straight passage for the baffies, they may be of somewhat less thickness than the corrugated baffles of Figs. 6 and 7. The core may be provided with a tank-securing ring 66 identical with that shown in Fig. 10 and the tank 68 may be secured to the rings in the same v manner.

Having thus described the invention, I claim:

1. Heat exchange apparatus comprising a core having a large number of closely-spaced thinwall tubes arranged in groups separated by straight narrow spaces, means for securing the tubes at their ends, said securing means having provision for forming said separating spaces, a plurality of thin sheet-metal baffles insertable in said spaces from the side of the core and extending across the core and between said securing means, sealing material joining one edge of each bafile along the entire edge thereof against the securing means at one end of the core, alternate baflles having large liquid-pass openings at opposite ends, each bafile having spacing projections formed in the surface thereof to engage adjacent groups of tubes, the baffles being retained solely by said sealing material and said frictional engagement, each baflie having bent wing portions extending outwardly beyond the core, and a shell surrounding and secured to the core and engaging said wing portions throughout their length.

2. Heat exchange apparatus comprising a core having a large number of closely-spaced thinwall, tubes arranged in groups separated by straight narrow spaces, headers to which the ends of the tubes are secured, a plurality of thin sheet-metal bafiles insertable in said spaces from 15 the side of the core and extending across the core and between said headers, sealing material joining one edge of each baflle along the entire edge thereof against the header at one end of the core, alternate bafiles having large liquid-pass openings at opposite ends, each baflle having spacing projections formed in the surface thereof to engage adjacent groups of tubes, the baffies being retained solely by said sealing matelarge number of closely-spaced thin-wall tubes having polygonal end portions to form a tube bundle, means for securing the end portions of adjacent tubes together, spacing strips between the polygonal end portions of tubes of selected rows to divide the core into groups of tubes separated by straight narrow spaces, a plurality of thin sheet-metal baflles insertable in said spaces from the side of the core and extending across the core and between said strips, sealing material joining one edge of each baflie along the entire edge thereof against the strip at one end of the core, alternate baffles having large liquid-pass openings at opposite ends, each baffle having spacing projections formed in the surface thereof to engage adjacent groups of tubes, the baflles being retained solely by said sealing material and said frictional engagement, each baflle having bent wing portions extending outwardly beyond the core, and a shell surrounding and secured to the core and engaging said wing portions throughout their length.

JOHN E. WOODS.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date Re 23,144 Andersen Sept. 6, 1949 1,367,881 Lea Feb. 8, 1921 1,689,910 Brocklebank Oct. 30, 1928 1,787,086 Pew, Jr. Dec. 30, 1930 1,803,035 Potter Apr. 28, 1931 2,146,614 Bergdoll Feb. 7, 1939 2,293,960 Young Aug. 25, 1942 2,520,821 Woods et a1 Aug. 29, 1950 FOREIGN PATENTS Number Country Date 521,652 Great Britain May 28, 1940 522,740

Great Britain -June 26, 1940

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