US3097165A - Fuel filtering and heater combination - Google Patents

Description

July 9, 1963 w. KASTEN FUEL FILTERING AND HEATER COMBINATION 3 Sheets-Sheet 1 Filed Oct. 26, 1959 Ill/l/I/II INVENTOR. WHL 72 164575 ATTOIPA/E) July 9, 1963 w. KASTEN 3,097,155

FUEL FILTERING AND HEATER COMBINATION Filed Oct. 26, 1959 s Sheets-Sheet :s

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W41 72" K4575 BY W 1% 3,097,165 Patented July 9, 1963 3 097 165 FUEL FILTERING AhlD IIEATER COMBINATION Waiter Kasten, Madison Heights, Mich assignor to The Bendix Corporation, South Bend, Inch, a corporation of Delaware Filed Oct. 26, 1959, Ser. No. 848,559 8 Claims. (Cl. 210-133) The present invention relates to fuel filtering and heater devices of the type disclosed in my copending application Serial No, 814,617, and more particularly to certain improvements relating thereto.

One of the Objects of this invention is to provide a single unit which functions as a filter deicer, fuel filter, fuel heater and lube oil cooler.

Another object of this invention is to provide a single unit of the type described wherein lube oil is utilized as the primary heat source and compressor bleed air is utilized as an auxiliary heat source.

A further object of this invention is to provide a single unit of the type described which incorporates a Single or a plurality of safety chambers for preventing intermixing of oil, air and/or fuel in case of leaky brazed joints.

A still further object of this invention is to provide a head casting for a single unit of the type described which includes all of the necessary inlet and outlet passages and requisite partition means therebctwcen for the fuel, oil, and air passing through said unit.

An important object of this invention is to provide a single unit of the type described incorporating a by-pass valve arrangement which permits continued flow of fuel along the complete length of the heat transfer means, located within the filter elements, under clogged filtering conditions.

An additional object of this invention is to provide means on the downstream side of each filter element which will divide the fuel into relatively thin streams, so that heat may be transferred thereto in a more efiective manner.

A further object of this invention is to provide a fluted filter element support which will aid in extending the service life of the associated filter element.

Other objects and advantages will become apparent from the following description and accompanying drawings, wherein:

FIGURE 1 is a view in partial section of one embodiment incorporating my invention;

FIGURE 2 is a sectional view taken along line 2-2 of FIGURE 1, showing only one set of heater tubes within a filter element;

FIGURE 3 is a sectional view of a portion of another embodiment incorporating my invention;

FIGURE 4 is a sectional view of a portion of a further embodiment incorporating my invention;

FIGURE 5 is a sectional view taken along line 5-5 of FIGURE 4;

FIGURE 6 is a sectional view of a portion of a still further embodiment incorporating my invention;

FIGURE 7 is a sectional view taken substantially along line 7-7 of FIGURE 6;

FIGURE 8 is an enlarged view partially in section with portions broken away for clarity of a single filtering element and the heat transfer means located therein;

FIGURE 9 is a sectional view taken along line 9-9 of FIGURE 8;

FiGURE 10 is an enlarged sectional view of a portion of a flexible filter element and its fluted support member; and

FIGURE 11 is a view similar to FIGURE 10 showing the filter element in a flexed position.

Referring to FIGURES 1 and 2 of the drawings, it will be noted that my fuel filtering and heater device includes a head 10 having a plurality of annular chambers 12, 14, 16, 18 and 20 formed therein. Chambers 12 and 14 communicate with lube oil inlet and outlet ports 22 and 24, respectively, while chambers 16 and 18 communicate with compressor bleed air inlet and outlet ports 26 and 28, respectively. Safety chamber 20 communicates with a leak detector port 30'. A fuel bowl 32 is suitably connected to head 10 through means of a bolt 33 and forms a fuel chamber 34 therewith which communicates with fuel inlet and outlet ports 36 and 38. Located in fuel chamber 34 and interposed between the fuel inlet and outlet ports 36 and 38 is a retainer plate 40 which is held in position by a spring 42. A plurality of filter elements 44 are suitably connected to retainer plate 40 and are arranged in inner and outer concentric rings. These filter elements may consist of tubular screens, wire wound elements, ribbon elements or any other types of elements having reasonably good conductivity which could be made in a wrap-around or substantially cylindrical unit and attached to the retainer plate 40. Each of the filter elements contains a lay-pass valve 46 at the lower end thereof for purposes to be subsequently explained. Located within and in contact with each of the filter element of the outer ring are a plurality of U-shaped tubes 48 each of which has one end communicating with oil inlet chamber 12 and the other end communicating with oil outlet chamber 14. A plurality of U-shaped tubes 59 are similarly located within and in contact with each of the filter elements 44 of the inner ring, but each of these tubes has one end communicating with air inlet chamber 16 and the other end communicating with air outlet chamber 18. The tubes 48 and 50 may be formed of any suitable noncorrosive material having relatively high conductivity and may be nested in sets of two, three or more pairs, as desired. A water drain plug 52. is provided for removal of any free water that may accumulate in the bottom of the bowl.

Operation of the device is as follows: Hot lube oil enters chamber 12 through inlet port 22, fiows through the U-shaped tubes 48 in the outer ring into chamber 14 and leaves the device via outlet port 24. The fuel to be filtered enters the fuel inlet port 36, flows through the filter elements 44 from the outside to the inside and leaves the unit via fuel outlet port 38. Any contaminants in the fuel will be deposited on the outside of the filter media and can be readily removed by back-flushing or cleaning. Since the U-shaped tubes 48 are physically in contact with the filter elements 44, heat from the hot lube oil will be transferred directly to the filter surfaces, through means of conduction, to prevent possible clogging of the filter elements by formation of ice thereon. Since the fuel, once inside of the filter elements, must fiow along the heater tubes 48, the fuel will be heated to a temperature about +32 F. and the oil will be cooled. It has been found, however, that lube oil does not normally contain sufiicient heat to heat the fuel under all flight conditions, For example, at the initial start of a flight, the fuel is still fairly warm and very little heat is required, but during very long flights at high altitudes, when the fuel may have cooled to -50 F. or lower and the engines are throttled back to cruising, the lube oil does not get hot enough to bring the fuel above +32 F. In order to obviate this difficulty additional heat is provided by utilizing compressor bleed air as a second heat source. Thus, hot compress-or bleed air enters chamber 16 through inlet port 26, flows through the U-shaped tubes 50' of the inner ring into chamber 8 and leaves the device via outlet port 28. Heat is transferred from the inner ring of heater tubes 50 to the filter elements 44 and the fuel flowing therealong in the same manner as that described with respect to the heater tubes 48 in the outer ring. Thus, the outer ring of heat transfer tubes and filter elements constitutes a filter deicer-fuel filter-oil cooler-fuel heater combination, and the inner ring which utilizes compressor bleed air as auxiliary heat is essentially only a filter deicer-fuel filter-fuel heater combination. Since one of the purposes of my unit is to cool the lube oil flowing through tubes 48, such lube oil will flow therethrough continuously. But, since heat may not be required at all times through inner U-shaped tubes 50, flow of compressor bleed air therethrough may be controlled by any suitable means, so that flow therehrough will be intermittent in any predetermined desired manner.

In order that the unit will always remain effective as an oil cooler, I have utilized individual by-pass valves 46 in the bottom of each filter element 44 so that if any filter clogging occurs, fuel will enter the bottom of the filters and flow past the complete length of the heat transfer tubes to cool the oil flowing therethrough. By o locating the by-pass valves, it will be obvious that heat exchange will always occur between the fuel and the oil regardless of the condition of the filter elements.

Since the weakest part of most conventional heat exchangers is the brazed joints where the heat transfer tubes are attached to the housing, any fractures and subsequent leakage will leak fuel into the oil cooler section and cause fire or engine failure. In my proposed arrangement, this danger has been eliminated by interposing a separate safety chamber between the fuel section and the oil compressor bleed air compartments. This safety chamber is vented to the atmosphere via port or may be connected to an expansion chamber having a pressure sensing valve (not shown) for detecting leaks.

The FIGURE 3 embodiment is essentially the same as that of FIGURE 1 except that the filter elements 44 are now open at both ends and are equipped with an additional retainer plate 54 at the lower end thereof. Furthermore, the multiple by-pass valves 46 of FIGURE 1 have been replaced by a single by-pass valve 56 in the lower retainer plate 54 which will permit, during clogged filtering conditions, flow of fuel from the fuel inlet port 36 to the lower open end of the filter elements 44, via a plurality of openings 58 located in a cylindrical extension 60, of the lower retainer plate 54. Thus, flow will be from one open end of the filter elements to the other open end.

Referring to FIGURES 4 and 5, it will be noted that i this embodiment is similar to the embodiment shown in FIGURE 3, except that an additional safety chamber 62 has been added for preventing intermixing of the various fluids in the event that one of the thin small diameter heat transfer tubes 48, 50 breaks. transfer from the tubes 48, 50 to the fuel is improved by attaching hollow externally fluted cylinders 64 to the head so that one end of each cylinder opens into chamber 62. The other end of each cylinder 64 is closed. The arrangement is such that the fluted cylinders 64 surround and are in contact with the heat transfer tubes 48, 50, and are in turn surrounded by the filter elements 44. The hollow portion of the fluted cylinder is filled with metallic sodium (suitably sealed therein) which serves as an effective heat transfer medium between the heater tubes and the filter elements. The fins 66 formed on the external surface of the fluted cylinder (see FIGURE 5) are in intimate contact with the filter elements, so that after the fuel has passed through the filter elements it will flow along the outer grooves 68 formed by the fins. In this manner the fuel is divided into very thin streams which are surrounded by metal so that heat to be transferred from the heating media can be transferred to the fuel without having to go through a large mass of fuel. It will be noted that there is no direct connection between the outside of the heat transfer tubes and the fuel chamber. If, for any reason, one of the small heater tubes should break, oil or air pressure will build up in the chamber 62. A pressure sensitive device (not shown) if con- In addition heat 4 nected to this chamber, could be used to shut off the oil or bleed air supply to the unit and prevent further damage.

Another feature of the fluted cylinders 64 is that an automatic self-cleaning characteristic results when the cylinders are utilized in conjunction with flexible filter elements such as those made of metal screen. During the early service life of the filter elements, when the outer surface of the elements is relatively free of contaminants, the flexible filter element 44 will maintain a position relative to the cylinders 64, as shown in FIGURE 10. If we assume that under a given set of conditions of fuel flow, the pressure loss through the filter element is 1 p.s.i., then We may have an external pressure (outside the filter element) of 2 p.s.i. and an internal pressure (inside the screen) of 1 p.s.i. As solids accumulate on the external surface of the filter element the pressure drop thereacross will gradually increase to a point at which the filter element will flex inwardly between fins 60, as shown in FIGURE 11. Such a flexing may occur, for the same given flow conditions, when the external pressure reaches 4 p.s.i. while the internal pressure remains at l p.s.i. Any further increase in the pressure differential would normally open the by-pass valve means associated with the particular filter element. If we assume that the bypass valve is set at a 4 p.s.i. differential pressure, it will open soon after the differential pressure exceeds 4 p.s.i. The moment this happens the pressure inside of the flexible filtering element will rise above the l p.s.i. value and since the dynamic head approximates the static head the by-pass valve will remain open even though the external filter pressure is reduced to less than 4 p.s.i. This occurrence reduces the external load on the filter elements and increases the pressure inside of the tubes thereby causing a flexure of the screen elements in reverse. This reverse flexing dislodges some of the contaminants so that normal filtering action re-occurs and the by-pass valve returns to its closed position. As a result of this self purging action the effective filtering life of the element is increased considerably.

Referring to FIGURES 6, 7, 8 and 9, it will be seen that this embodiment is essentially the same as that shown in FIGURE 4, except that the safety and sodium chambers have been eliminated and the heating medium is carried directly inside of the fluted cylinders 64, which previously contained the small heater tubes 43, and the sodium as the heat exchange medium. These fluted cylinders are now provided with an insert 70 having radial spokes extending from the center thereof. Basically this insert serves the purpose of directing the flow of the heat transfer medium from the open end of the hollow externally fluted cylinder 64 to the closed end thereof over substantially one-half of the effective area of the tube. After it reaches the closed end of the cylinder, the how is reversed and it passes along the other half of the cylinder to the open end. Therefore, it is necessary that the insert be spaced from the bottom end of the fluted cylinder 64 by approximately a distance equal to the diameter of the cylinder. The fuel to be heated flows through the filter elements 44 and along the grooves 68 formed on the fluted cylinder 64 and thence to the fuel outlet port. The FIGURE 5 embodiment also uses the single by-pass valve 56 which permits flow from one open end of each filter element, along grooves 68 and out the opposite open end in a manner previously described when clogged filtering conditions occur.

The several practical advantages which flow from my invention are believed to be obvious from the above description, and other advantages may suggest themselves to those who are familiar with the art to which this invention relates.

Having thus described the various features of the invention, what I claim as new and desire to secure by Letters Patent is:

1. A fluid filtering and heater device comprising a head having a first chamber formed therein communicating with a first inlet port for permitting ingress of a first fluid, a second chamber formed therein communicating with a first outlet port for permitting egress of said first fluid, a third chamber formed therein communicating with a second inlet port for permitting ingress of a second fluid, and a fourth chamber formed therein communicating with a second outlet port for permitting egress of said second fluid, a bowl operatively connected to said head and forming a fifth chamber therewith, said fifth chamber communicating with a third inlet port and a third outlet port for permitting ingress and egress of a third fluid, a retainer plate located in said fifth chamber and interposed between said third inlet and outlet ports, a plurality of tubular members operatively connected to said head and extending through said retainer plate, said tubular members each having two separated openings located therein, some of said tubular members having one of said openings communicating with said first chamber and the other of said openings communicating with said second chamber and others of said tubular members having one of said openings communicating with said third chamber and the other of said openings communicating with said fourth chamber, a plurality of filter elements of the outside-in type operatively connected to said retainer plate for filtering the third fluid flowing from said third inlet port to said third outlet port, said filter elements each surrounding one of said tubular members and being in contact therewith, and by-pass means interposed between the third inlet port and the downstream side of said filter elements for permitting continued flow of said third fluid inside of said filter and along said tubular members under clogged filtering conditions.

2. A fluid filtering and heater device as defined in claim 1 wherein a safety chamber is formed in said head and is located between the fifth chamber and the remaining chambers for insuring against intermixing of said various fluids.

3. A fluid filtering and heater device as defined in claim 1 wherein a plurality of safety chambers are formed in said head and are located between the fifth chamber and the remaining chambers for insuring against intermixing of said various fluids.

4. A fluid filtering and heater device as defined in claim 1 wherein said by-pass means includes a plurality of bypass valves each of which is operatively connected to only one of said filter elements and is functionally independent of the other by-pass valves.

5. A fluid filtering and heater device as defined in claim 1 wherein said by-pass means includes a single by-pass valve interposed between said third inlet port and the downstream side of all of said filter elements.

6. A fluid filtering and heater device comprising a housing having a first chamber formed therein communicating with a first inlet port for permitting ingress of a first fluid, a second chamber formed therein communicating with a first outlet port for permitting egress of said first fluid, a third chamber formed therein for communieating with a second inlet port and a second outlet port for permitting ingress and egress of a second fluid, partition means for separating said chambers from each other, means located in said third chamber and interposed between said second inlet and outlet ports for filtering the fluid flowing therebetween, said last named means including a pair of retainer plates and a plurality of porous filter tubes of good conductivity and of the outside-in type having the opposite ends thereof opening through said retainer plates, a plurality of hollow non-porous externally fluted members operatively connected to said housing, one of which is located within and in contact with a substantial portion of the length of each of said filter tubes for transferring heat thereto and to the second fluid flowing along said fluted members on the inside of said filter tubes to thereby prevent the formation of ice on the filter tubes and in the second fluid flowing through said filter tubes, said fluted members each having an open end and a closed end, means operatively connected to said housing and located within the hollow portion of each of said fluted members for forming two separated openings and a flow path therebetween, one of said openings communieating with said first chamber and the other of said openings communicating with said second chamber, and bypass valve means interposed between the second inlet port and the downstream side of said filter tubes for permitting continued flow of said second fluid along the external surface of said fluted members under clogged filtering conditions.

7. A fluid filtering and heater device as defined in claim 6 wherein the means operatively connected to said housing and located within the hollow portion of each of said fluted members comprises an insert having radially extending spokes in contact with the hollow portion of said fluted member, said insert being spaced from the closed end of said fluted member.

8. A fluid filtering and heater device as defined in claim 6 wherein said porous filter tube is formed of a material capable of flexing into the flutes of said fluted member as a result of variations in the differential pressures acting thereacross to thereby provide a self-cleaning action.

References Cited in the file of this patent UNITED STATES PATENTS 654,592 Barr July 13, 1900 813,918 Schmitz Feb. 27, 1906 1,075,978 Joerin et al Oct. 14, 1913 1,856,771 L-oefller May 3, 1932 2,057,932 Bolser Oct. 20, 1936 2,183,616 Korte Dec. 19, 1939 2,212,932 Fairlie Aug. 27, 1940 2,300,849 Tauch Nov. 3, 1942 FOREIGN PATENTS 12,539 Great Britain June 2, 1904 70,805 Netherlands Aug. 16, 1952

Claims (1)

1. 6. A FLUID FILTERING AND HEATER DEVICE COMPRISING A HOUSING HAVING A FIRST CHAMBER FORMED THEREIN COMMUNICATING WITH A FIRST INLET PORT FOR PERMITTING INGRESS OF A FIRST FLUID, A SECOND CHAMBER FORMED THEREIN COMMUNICATING WITH A FIRST OUTLET PORT FOR PERMITTING EGRESS OF SAID FIRST FLUID, A THIRD CHAMBER FORMED THEREIN FOR COMMUNICATING WITH A SECOND INLET PORT AND A SECOND OUTLET PORT FOR PERMITTING INGRESS AND EGRESS OF A SECOND FLUID, PARTITION MEANS FOR SEPARATING SAID CHAMBERS FROM EACH OTHER, MEANS LOCATED IN SAID THIRD CHAMBER AND INTERPOSED BETWEEN SAID SECOND INLET AND OUTLET PORTS FILTERING THE FLUID FLOWING THEREBETWEEN, SAID LAST NAMED MEANS INCLUDING A PAIR OF RETAINER PLATES AND A PLURALITY OF POROUS FILTER TUBES OF GOOD CONDUCTIVITY AND OF THE OUTSIDE-IN TYPE HAVING THE OPPOSITE ENDS THEREOF OPENING THROUGH SAID RETAINER PLATES, A PLURALITY OF HOLLOW NON-POROUS EXTERNALLY FLUTED MEMBERS OPERATIVELY CONNECTED TO SAID HOUSING, ONE OF WHICH IS LOCATED WITHIN AND IN CONTACT WITH A SUBSTANTIAL PORTION OF THE LENGTH OF EACH OF SAID FILTER TUBES FOR TRANSFERRING HEAT THERETO AND TO THE SECOND FLUID FLOWING ALONG SAID FLUTED MEMBERS ON THE INSIDE OF SAID FILTER TUBES TO THEREBY PREVENT THE FORMATION OF ICE ON THE FILTER TUBES AND IN THE SECOND FLUID FLOWING THROUGH SAID FILTER TUBES, SAID FLUTED MEMBERS EACH HAVING AN OPEN END AND A CLOSED END, MEANS OPERATIVELY CONNECTED TO SAID HOUSING AND LOCATED WITHIN THE HOLLOW PORTION OF EACHH OF SAID FLUTED MEMBERS FOR FORMING TWO SPEARATED FLOW PATH THEREBETWEEN, ONE OF SAID OPENINGS COMMUNICATING WITH SAID FIRST CHAMBER AND THE OTHER OF SAID OPENINGS COMMUNICATING WITH SAID SECOND CHAMBER, AND BYPASS VALVE MEANS INTERPOSED BETWEEN THE SECOND INLET PORT AND THE DOWNSTREAM SIDE OF SAID FILTER FOR PERMITTING CONTINUED FLOW OF SAID SECOND FLUID ALONG THE EXTERNAL SURFACE OF SAID FLUTED MEMBERS UNDER CLOGGED FILTERING CONDITIONS.

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