US2830798A - Axial flow oil cooler having cross baffles - Google Patents

Description

April 15, 1958 s. K. ANDERsr-:N

AXIALvFLOW OIL COOLER HAVING CROSS BAFFLES 5 Sheets-Sheet 1 Filed Feb. 15, 1953 April 15, 1958 s. K. ANDERSEN 2,830,798

AXAL FLOW OIL COOLER HAVING CROSS BAFFLES A frezen/5] April 15, 1958 s. K. ANDERSEN 2,830,798

AXIAL FLOW OIL COOLER HAVING CROSS BAFFLES Filed Feb. l5, 1953 5 Sheets-Sheet 4 1N V EN TOR.

April 15, 1958 s. K. ANDERSEN 2,830,798

AXIAL FLOW OIL COOLER HAVING CROSS BAFFLES .4 Walen/5 V ted tat ten N'le XIAL FLOW GIL CQOLER HAVING CRSS BAFFLES Soren K. Andersen, Los Angeles, Calif., assignor to The Garrett Corporation, Los Angeles, Calif., a corporation of California Application February 13, 1953, Serial No. 336,756

3 Claims. (Cl. 257-128) This invention relates to fluid conditioning devices such as oil coolers, for use under widely varying temperature conditions, including extremely low temperatures such as are encountered in airplane use, this application being a continuation-impart olf applicants application for Axial Flow Oil Cooler Having Cross Bales, Serial No. 708,666, now abandoned.

One of the problems met with in oil coolers for aircraft is the maintaining of the proper ilow of engine lubricating oil. There are times when such low temperatures are encountered, that the oil congeals, or tends to congeal, beginning in the center of the cooler and spreading outwardly. If the oil congeals, it is then necessary to thaw or decongeal the oil in order to maintain such oil in proper condition. It is therefore an object of the present invention to provide a highly eicient oil cooler which will have optimum anti-congealing and decongealing characteristics, and, at the same time, have adequate cooling capacity.

In devices of the present character, particularly those that are cylindrical in shape, there are portions about the periphery of the radiator core where tubes are left out due to interference or lack of clearance with the radiator shell. Consequently, the spaces where these tubes are lacking are of greater cross sectional dimension than the spaces resulting from the normal spacing of the tubes, and there is a tendency for the oil to flow through these larger passages rather than through the smaller passages of the interior parts of the core.

It is therefore another object of the invention to provide means which will prevent bypassing of oil through v these larger passages at the periphery of the shell.

In oil coolers of the present character there are bafes which cause the oil to flow through a number of chambers extending longitudinally of the air tubes to provide a tortuous ilow passage, and in the present arrangement the means which prevents the bypassing of oil through the above mentioned larger passages comprises cross bailles about at least a portion of the interior periphery of the cooler shell. strictions which increase the speed of flow at said restricted portions and cause the oil at their regions to flow inwardly toward the central portion of the chambers or the ilow passage where congealing is most likely to occur first.

It is a further object of the invention to provide a device of this character wherein the ilow of oil in each chamber is increased gradually toward its middle or longitudinal center by suitably shaping the baffle opening or ports to provide ow paths gradually decreasing in length toward the middle of the chamber.

Further objects and advantages of the invention will be brought out in the following part of the specication.

Referring to the drawings, which are for illustrative purposes only,

Fig. l is a cross sectional view of an oil cooler embodying the present invention, taken on line 1-1 of Fig.

These cross baflles also form re.

Fig. 2 is a section taken on line 3-3 of Fig. l;

Fig. 3 is a section taken on line 3-3 of Fig. 1;

Fig. 4 is a sectional view of the control valves of the device such as would be taken on line 4-4 of Fig. l;

Fig. 5 is a plan view of the oil cooler with the valve mechanism removed;

Fig. 6 is an enlarged partial section of a header plate with an adjacent baille;

' Fig. 7 is an enlarged fragmentary end view of the heat exchanger showing a portion of the header plate with the air tubes therein;

Fig. 8 is an enlarged fragmentary view showing a portion of one of the cross bail-les;

Fig. 9 is an enlarged fragmentary view taken on line -9 of Fig. 8;

Fig. 10 is a sectional View similar to Fig. 3 by showing an alternative type of baille;

Fig. ll is an enlarged fragmentary view showing a portion of the alternative type of cross baffle;

Fig. l2 is a view taken on line l2-12 of Fig. l1; and

Fig. 13 is an enlarged fragmentary view showing a header plate with the tubes secured therein.

As an example of one form in which the invention may be embodied, there is shown in the drawings a heat exchanger comprising a casing comprisnig a shell l0, of tubular form, having a radiator core therein, indicated generally at lll. The radiator core 1l comprises a plurality of bundles or groups of parallel radiator tubes 12, which are mounted at their ends in header plates 13 (Figs. 2 and 7) which form the end walls of the heat exchanger casing. The header plates 13 have openings lil to receive the respective tubes l2 which are first inserted in openings la, and then are expanded to form a sealed joint (by a swaging tool). Ferrules 15, having one end 16 formed hexagonally, are then inserted in the expanded tube and likewise expanded to secure the tube and ferrule. This operation is then repeated at the opposite end of the cooler.

Withinthe core are a plurality of substantially parallel laterally spaced baies 20, 2l, 22, 23, 24, 2S, 26, and Z7, extending longitudinally of the shell 10 and inclinedly dispo-sed therein, as shown in Fig. l.

The baffles E to 27 deiine compartments 28 which are connected together in series to form a tortuous channel or flow path 3d for the oil passing through the cooler. As shown, the baffles 2t) to 27 inclusive, have their ends alternately spaced from the adjacent header plates to provide openings 29, said spaced ends of the baffles being notched or cut out in the form of a wedge or V, as indicated at 29a in Figs. 2 and 3, with the base of the notch extending substantially across the entire width of the ilow path, and with the apex or deepest part of the V adjacent the longitudinal center of the baflles. The ilow of oil through the cooler is therefore distributed across substantially the entire width of the chamber, but, due to the gradually decreasing length of the llow paths, the flow of oil increases gradually toward the center of the chamber where congealing is most likely to occur, and thus reduces congealing to a minimum.

Means for mounting the baffles in the shell comprise a pair of flanges for each of said bales. Each of said llanges 35 forms one side of an angle piece which has its opposite side or flange 36 `attached to the adjacent wall of the shell ld by welding or the like. The longitudinal side edge portions of the baffles are disposed between the flanges 35, the spaces between said flanges being just wi-de enough to snugly receive the baffles, and are spot welded thereto;

The ends 37 of the beides, opposite the ports 29, are received in recesses 33 provided therefor in the respective ladjacent header plates 13.

The ends `of the shell 10 are turned laterally outwardly M to provide anges 39. Flanges 13a of the header plates 13 are disposed between said ilanges and the anges 40 of the cooler mounting ilanges 41, the flanges 39, 13a, and 41 being secured by brazing or the like.

In devices of the present character, particularly those that are cylindrical in shape, there are portions about the Aperiphery of the radiator core where tubes are left out due to interference or lack of clearance with the radiator shell, thus leaving a plurality of spaces 42 of greater cross sectional area than the spaces 43 resulting from the normal spacing of the tubes. Consequently there is a tendency for oil to ilow through these larger passages on the periphery of the core rather than through the smaller passages of the interior parts of the core. Means are therefore provided to divert this flow from the outer shell of the cooler toward the relatively colder tubes in the interior of the core where congealing is more likely to occur. This means comprises one or more sets of arcuate cross baffles 45, secured to the interior wall of the shell by brazing, Vor by other suitable means. Each set consists of two cross bales spaced longitudinally in the shell and arranged in substantially the same plane on diametrically opposite sides of the shell, with their ends spaced circumferentially apart. In the present instance Fig. 3 of the drawings shows four cross bafes arranged to form two sets, but as many, or as few, of these sets of cross baffles as are desired may be used.

The cross baiiies 45 are provided with openings 46 therein, for reception of the radiator tubes 12. The cross baflies may have marginal notches 48 to accommodate the flanges 36 of the angle pieces 35, as shown in Fig. 8, in which casethe remaining portion of the cross baies would be received in marginal notches 47 (Fig. 9) cut in the respective bales Z to 27, or, as an alternate method of installation, the cross bafes may abut the shell throughout their entire length, in which case the marginal notches corresponding to the notch 47 in Fig. 9 would be cut through both the bafie and the flanges and 36 of the angle piece.

The cross baffles 45, in Iaddition to preventing the ow of oil through the large passages or spaces 42 at the periphery of the core, form cross sectional restrictions in the cooler which causes a turbulence to be set up toward the center of the core and increases the speed of flow through the central portion of the flow path.

The shell 10 is provided with apair of inlet ports 50 adjacent one end and between the planes of the adjacent ends of the cross baffles. Outlet ports 51 are provided on the diametrically opposite side of the shell.

The cooler is provided with a warm-up jacket, which may be formed of sheet metal and secured to the shell 10 by brazing or by any other suitable means, and provides oil passages exteriorly of the shell 10, as will be described more particularly hereinafter.

As shown, the jacket comprises two portions, or mufs, indicated generally at 52 and 53, which communicate with the inlet and outlet ports and 51 respectively. The warm-up jacket is provided with an oil inlet opening 54 which communicates with the muff 52, a common oil outlet opening 55 which communicates with the mui 53, and la bypass inlet 56, said inlet opening 54 and bypass opening 56 being in parallel with each other.

A partition 57 in the space between the outer mufl'.' wall and the exterior of the shell 10 closes off communication between the muff 52 and the muff 53, said partition extending to a point of junction with the end wall 58 of the jacket which extends inwardly from the general plane of the adjacent end wall. Thus an inlet passage or duct 52a is provided between the inlet S4 and the shell inlet ports 50. A second partition 59, in said space, extends between the oil outlet and the bypass inlet toa depressed channel 60. The partition 59 and the depressed channel 60 provide baffle means for defining, within the muff 53, an oil outlet duct or passage 53a on one side and a warmup bypass 61 on the other side.

Secured to the top of the oil cooler is a ange or collar 65, Fig. 4, having a at finished upper surface, against which a control head casing 66 is fitted and secured, as by means of screws 67. The flange is provided with a core inlet opening 68, a warm-up inlet opening 69, and a common outlet opening 70 extending vertically therein, said openings 68, 69 and 70 in turn being connected with the oil inlet 54, bypass inlet 56, and oil outlet 55 respectively.

The control head casing 66 has an inlet opening 71 in the side wall near one end thereof, and an outlet opening 72 in the side wall near the other end thereof. The openings 71 and 72 are connected to inlet and outlet couplings of the oil system not shown. The opening 71 communicates with an inlet chamber 73, and the opening 72 communicates with an outlet chamber 74, in the control head casing 66. The inlet chamber 73 is defined between the side walls of the casing 66, a pair of intermediate horizontal walls 75 and76, which are generally parallel to the top wall 77 of the casing, and a pair of transverse partition walls 78 and 79, joining the side walls and the walls 75 and 76. The outlet chamber 74 is defined between the top wall 77, the side walls, the bottom wall 80, an end wall S1, and a transverse partition wall 82 which joins the side walls, the bottom wall and the intermediate horizontal wall 75.

Between the inlet chamber 73 and the outlet chamber 74 respectively, are a pair of valve chambers 83 and 84. These chambers are separated by a partition wall 85 joining the side walls, and intermediate wall 75 of the casing 66, and are defined between the side walls and the walls 75, 79, 82 and 8S.

The walls 75 and 76 are joined to the end wall 86 of the casing 66, in which there is provided a cylindrical bore 87. The bore 37 communicates through the inlet chamber 73 with a port 88 in the wall 78. A direct bypass passage 89 extends from the bore 87 to the outlet chamber 74, being defined between the walls 75, 77, 78 and 66, and the side walls of the casing 66. Slidably mounted in the bore 87 and normally closing off the end of the passage 89 adjacent the bore 87 is a pressure relief valve 90. The valve 90 has a frusto-conical valve face 91 which is normally urged into seating arrangement with a valve seat defined at the perimeter of the port 88 in the wall 78, yielding pressure being supplied by a spring 92 reacting between the valve 90 and a cage 93 secured to the end wall 86 of the casing 66.

The valve 90 carries a stem 94 which extends through the chamber 73 and a port 95 in the wall 79. Mounted on the stem 94 and cooperating with the port 95 is a core protection valve 96.

Mounted in an opening 97 in the end wall 81 is the base portion 98 of a thermo-responsive valve unit 99 which includes a bimetallic coil 100 controlling the movement of a valve head 101 which cooperates with a port 102 within the wall 85. The valve unit 99 includes a tiange 103 which closesv an opening 104 in the wall 82 through which the valve unit projects. The head 101 is connected to the body of the valve unit by a bellows 105. The valve unit 99 is constructed in accordance with a disclosure contained in the application of Raymond W. Jensen for Cooler and Valve Therefor, Serial No. 612,947, filed August 27, 1945, now Patent No. 2,516,390 dated Iuly 25, 1950.

The chamber 83 is connected to the core inlet opening 68 and is adapted to be connected to the chamber S4 by yielding or opening movement of the valve 101, the chamber 84 being connected to the bypass inlet opening 56. The outlet chamber 74 is connected to the common outlet 55 when an outlet check valve 106 is opened. It is also connected to the outlet port 72.

In the operation of the device oil flowing into the control head inlet chamber 73, from the inlet 71, will normally flow past the open valve 96 into the chamber 83 between the chambers 73 and 84. When the temperature of the oil is at a normal level, the thermo-responsive head 101 will be closed against the port 102, and the oil will be routed from the chamber 03 through the inlet ports 68 and Srl, through inlet duct 52a and thence through the shell inlet ports 50 and into the core. it will then pursue a tortuous path (arrows 3d) through the core 11, leaving the same by way of the shell outlet ports 51, the outlet passage 53a of the warm-up muli 53. From the warmup muli" 53 the oil will pass through the outlet ports 55' and '70, past the outlet check valve 1.06 and into the outlet chamber 7d, where it will wash the thermo-responsive coil 160 to determine the position of the valve 101.

ln the event 'the temperature of the outilowing oil drops below a predetermined level, the valve head 191 will respond with opening movement, permitting a portion of the oil to be bypassed through the port 1&2, charnber Eid, ports 69 and 556, and into the bypass passage or duct 61.

lt may be noted at this point that the warm-up muti covers one side of each of the compartments 28 delined between the battles to 2'7. Thus, one side of each compartment is in heat exchange relation with the path of rlow of warm-up oil in the warm-up jacket 53. This stimulates the thawing of a congealed cooler by liquifying the oil in the spaces on the sides of the core compartments, and initiating the flow of oil in the tortuous llowpath formed collectively by these spaces.

With the above described jacket arrangement, it will be obvious that the cooler as a whole will be relatively light, that there will be less oil therein, due to the fact that the jacket does not extend around the entire periphery of the cooler.

The amount of bypassing through the warm-up muli will depend upon the extent of opening of the valve head lill. 'ln the event of congealrnent, the pressure in the inlet chamber 73 may rise to a point where the valve 91 is forced to a position establishing communication between the chamber 73 and the direct bypass S9, at the same time closing the valve 96. The same results may occur in the event of a sudden surge of pressure at the inlet. Excessive pressure in the chamber 83, inadequate to cause the surge valve to operate but suilcient to cause the valve head 101 to yield, may be relieved through the bypass, even though the thermostat is calling for the closed position of the valve head 101.

Referring to Fig. 10, the bales defining the tortuous llow path through the cooler are indicated at 125. Each of these baffles is rectangular in shape and is of less length than the length of the cooler so as to provide a rectangular opening 126 at alternate ends of the cooler.

Adjacent the respective ends 127 of the bailles 125 which define one side of the openings 126 are a plurality of openings 128 which are spaced apart transversely with respect to the baille 125 and also spaced in substantially parallel relationship to the edges 127. Between the holes or openings 128 and the edge 127 are a plurality of larger openings 130 which are aligned and spaced apart transversely with respect to the bales 125. lThis arrangement provides elective anti-congealing characteristics for the cooler and also structural strength, particularly when used in the elliptical type of cooler.

The type of cross baille 135 shown in Figs. 1l and 12 differs from that hereinabove described with particular reference to Figs. 1 and 8 in that said bathe 135 has notches 136 in its free edge for reception of edge portions of the battles 126. It is to be noted that the battles 126 are also notched at 137 and that the notches 136 and 137 interlock. This interlocking of the notch in the bellies and the cross bales holds the parts securely and locating of the parts correctly during assembly is facilitated. Also there is a substantially uniform number of tubes around the inside of the shell with the cross balles 135 and it is to be noted that the free edges 139 of these cross `'Dalles are without sharp projecting parts and conform to the tube pattern in Fig. 13. The ends of the tubes 12 are llush with the outer surface 140 of the header plates 13.

l VVclaim:

1. In an oil conditioning device: a cylindrical shell having an inlet and an outlet; a radiator core substantially lining said shell and comprising a plurality of radiator tubes extending longitudinally of said shell and being normally spaced apart, the outer tubes being closely adjacent to shell but there being spaces adjacent said shell of greater cross sectional area than the normal spaces between the tubes; means defining within said core a tortuous liow passage between the inlet and the outlet; a plurality of arcuate cross baliles secured peripherally to the interior of the shell and spaced apart longitudinally thereof, said cross baffles extending into the ow passage and transversely thereof and having openings therein for snug reception of the core tubes, said cross baes extending into said flow passage a distance substantially less than the radius of said shell but inwardly of said greater spaces.

2. ln an oil cooler having a cylindrical shell with an inlet and an outlet: a radiator core within said shell comprising thin walled tubes extending longitudinally of said shell, said tubes being arranged in a uniform pattern with a normally uniform spacing therebetween, there being spaces next to the shell of greater size than the normal spacing between the tubes; a plurality of battles within the radiator core extending longitudinally of said tubes, said battles being in substantially parallel relation to a plane forming a dihedral angle with reference to the axial plane of the cooler passing through said inlet and said outlet, said baflies being of less length than said core to provide openings at alternate ends of adjacent baies to provide a tortuous flow passage through the radiator core, each battle having a plurality of rows of perforations adjacent the edge defining said opening, said rows being substantially parallel to said edge and spaced laterally apart relative to each other; and cross `baiiies at the peripeheral sides of the core extending a distance into said core substantially less than the radius of the shell, but beyond said greater spaces, said cross bafdes being adapted to deflect inwardly iluid owing through said core, and having perforations for reception of said tubes.

3. In an oil cooler having a tubular shell with transverse end walls forming a chamber having inlet and outlet ports; a plurality of spaced parallel flat balles extending longitudinally of said tubular shell to divide said chamber into sections, opposite ends of adjacent battles being spaced from the adjacent end walls to establish communication between adjoining chamber sections and form a tortuous passage between said inlet and outlet ports, the marginal portion of said battles at the ends spaced from said end walls being formed to permit increased fluid flow adja cent the centers of said chamber sections; a core in said shell, said core having a plurality of tubes extending parallel to the side wall of said tubular shell and having fluid tight engagement with said end walls to form fluid passages extending longitudinally through said chamber sections; and a plurality of sets of generally diametrically opposed baffles spaced longitudinally of said shell and projecting from the sides thereof transversely into said chamber sections to reduce the cross-sectional areas of such sections in the region occupied by said core, said baliles deecting iluid flowing along the walls of said shell toward the centers of said chamber section.

References Cited in the tile of this patent UNITED STATES PATENTS 1,700,498 Hughes Jan. 29, 1929 1,764,200 Dean June 17, 1930 1,987,604 Corbett Ian. 15, 1935 2,301,665 Dykeman et al Nov. 10, 1942 2,376,198 Shaw May 15, 1945 2,474,689 Ramsaur June 28, 1949 U. S. DEPARTMENT OF COMMERCE PATENT OFFICE CERTIFICATE OF CORRECTION Patent Noa 2,830,798 Soren Ko Andersen April l5, 1958 It is hereby certified that error appears .in the printed specification of the abo've numbered patent requiring correction and that the said Letters` Patent should read as corrected below.

Signed and sealed this 3rd day of June 1958n (SEAL) Attest:

KARL H. AXLINE Corrlnssioner of Patents

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