US3278032A

US3278032A - Fuel pump and filter assembly

Info

Publication number: US3278032A
Application number: US505104A
Authority: US
Inventors: Russell F Smith
Original assignee: ACF Industries Inc
Current assignee: ACF Industries Inc
Priority date: 1965-10-15
Filing date: 1965-10-15
Publication date: 1966-10-11
Anticipated expiration: 1983-10-11

Description

United States Patent Ofiice 3,278,032 Patented Oct. 11, 1966 3,278,032 FUEL PUMP AND FILTER ASSEMBLY Russell F. Smith, Ferguson, Mo., assignor to ACF Industries, Incorporated, New York, N.Y., a corporation of New Jersey Filed Oct. 15, 1965, Ser. No. 505,104 Claims. (Cl. 210-181) This invention relates to a mechanical fuel pump and filter assembly and particularly to a design, in which the basic considerations are heat dissipation and cost reduction in fabrication.

This application is a continuation-in-part of my copending application Serial Number 182,304, filed March 26, 1962, and entitled, Fuel Pump, and now abandoned.

A major problem of fuel pump operation is that of minimizing vapor lock conditions, which occur during the operation of an engine at high ambient temperatures and at high speeds. Such vapor lock conditions are due to fuel vaporizing in the system and also occurring during a soak period when the engine stands after a prolonged operation at high speed at a high ambient temperature. The fuel line and fuel pump of the engine are packed closely adjacent to the engine and readily absorb heat from the hot engine parts, which condition tends to form vapor in that part of the fuel system. The fuel pump is particularly vulnerable to vapor in the fuel line and its efiiciency drops rapidly as vapor enters the pump.

Pumps of this type are conventionally made of cast metal housing structures, which due to their mass and thickness retain heat absorbed from the engine and from the hot fuel passing into the pump. It is thus an advantage to utilize a fuel pump that will retain a minimum of heat carried to it during engine operation. It is also desirable that the pump be able to rapidly conduct heat away from the fuel within the pump to minimize vapor formation.

Mechanical fuel pumps made of cast metal housings use an excessive amount of metal alloy and require considerable machining operations. In considering the problem of reducing the cost of fabrication of such pumps, it has been found that sheet metal construction lends itself advantageously for this purpose.

It is therefore one object of the invention to provide a novel pump and filter combination adapted to overcome the problem of fuel vaporization and vapor lock in a fuel system due to excessive heating of the fuel.

Another object is to provide a pump-filter unit utilizing primarily thin sheet-metal construction to encourage thereby cooling of the fuel during the pumping process.

A still further object of the invention is to provide a unit of the type described including a fuel inlet chamber adapted to circulate fuel for cooling the same during the pumping stroke.

Still another object of the invention is to provide a novel fuel pump having a filter element combined therewith for filtering fuel being pumped.

These and other objects of the invention will be clear to those skilled in the art from the accompanying description made in conjunction with the drawings.

This invention is directed to a novel design of a mechanical fuel pump and filter assembly in which heat dissipation is greatly increased by the use of thin walled metal housing structures and in which cost reduction is achieved by the use of shaped sheet metal parts. The fuel filter chamber is joined integrally with the pump housing structure to form a unitary assembly.

FIGURE 1 is a sectional view in elevation of the novel pump and filter assembly, in accordance with this invention, showing the unit assembly attached to a portion of an internal combustion engine and communicated with the fuel system of the engine schematically represented.

FIGURE 2 is a segmentary view in partial cross section of the fuel pump of FIGURE 1 taken at to the section of FIGURE 1.

FIGURE 3 is a partial sectional view in elevation of a fuel pump and filter assembly forming another embodiment of the invention.

FIGURE 4 is a sectional view of the valve structure of the pump of FIGURES 1-3.

FIGURE 1 discloses the pump and filter assembly of this invention connected to the crankcase 10 of an internal combustion engine 12. The pump portion of the pump and filter assembly includes a pump spring housing 14 attached to a pump housing portion 16. The pump housing portion 16 is a formed cylindrical construction, of iron, or steel, for example, and having a thickness in the order of 0.030. Pump housing 16 has a rim 18 bent up and inwardly over a flange 20 of the spring housing 14. The fastening of the rim 18 over flange 20 is done with sufiicient pressure so that the peripheral edge of a circular flexible rubber-coated fabric pump diaphragm 22 is tightly gripped between rim 18 and flange 20. This seals in a fuel-tight manner the diaphragm 22 to rim 18. This described method of attaching rim 18 to flange 20 eliminates the necessity of using screws through flange 20 which would require a larger flange area. Thus, flange 2G is kept to a minimum size, permitting the positioning of the pump within a smaller space.

The central portion of the pumping diaphragm 22 is made sulficiently rigid by a pair of

back plates

24 and 26 on opposite sides of the diaphragm 22.

Backing plates

24 and 26 are tightly fixed together with the pumping diaphragm 22 in between by spinning over the end 28 of a pump rod 30 extending through the several parts. This holds the plates and diaphragm between a shoulder portion 29 abutting the surface of plates 24 and the spunover head portion 28.

The other end of rod 30 is formed with a nail head 32 which is fitted into the forked end 34 of an actuating lever 36, which in turn is mounted for pivotal movement on a bearing pin 38 journalled in an extension 40 of the spring housing 14. A flexible noise-suppression wear pad 42 is positioned between the rod head 32 and the forked end 34 of the actuating lever '36. A pump driving spring 44 is positioned between the upper surface of backing plate 24 and a support eyelet 46, which is forced by the spring 44 to tightly seal the peripheral edge of a sealing ring 48 against a shoulder 50 of the spring housing 14. The actuating rod 30 passes through the center of sealing ring 48, which permits reciprocating motion of the rod but fits the rod with suflicient tightness to provide a wiping action. This prevents oil from the crankcase from penetrating into the portion of housing 14 enclosing the spring 44.

Spring housing 14 is fixed across an opening 52 through the wall of the crankcase 10 of the engine 12 .and may be attached to the crankcase 10 by fastening the housing to studs extending through the flange portion 56 of housing 14 from the crankcase 10. The operating lever 36 has an end 61) extending through the opening 52 into the crankcase of engine 12 and into contact with an engine driven eccentric cam 62.

A spring 64 is tensioned between a portion of the housing extension 40 of the lever arm 36 to hold lever end 60 against cam 62.

A sheet metal plate 51 having a pair of drawn cup portions 53 and 54 is mounted across the housing cup 16, as shown. The rim 55 of plate 51 is sealed around its periphery to the lip of housing 16 below the rim portion 18. The sealing of rim 55 may be done in any appropriate manner, such as by brazing or soldering.

During engine operation, the eccentric cam 62 is rotated and causes the pump operating lever 36 to oscillate up and down about pin 38. As viewed in FIGURE 1, the upward motion of the rocker arm end 34 pulls the pump rod 30 upwardly and tensions spring 44. Movement of operating lever 36 in a counterclockwise direction permits the spring 44 to press the pump rod and diaphragm 22 downwardly. The space between the plate 51 and the pump diaphragm 22 forms a pumping chamber 25.

A short inlet conduit 68 has one end extending through an aperture in the wall of the housing 16 and sealed thereto by swedging, brazing or soldering. A circular plate 70 is welded around its peripheral edge to the inside surface of housing 1.6 to seal off the portion of housing 16 enclosing cups 53 and 54. The space between plates 70 and 51 thus forms an inlet fuel chamber enclosing the cups 53 and 54. Thus, as fuel is introduced through inlet 68 to the chamber formed between plates 70 and 51, the fuel will be circulated to some extent and contacted by the thin walls of pump housing 16 to foster removal of heat through the circulated fuel. An aperture 66 in the bottom of cup 53 is for the passage of fuel from the inlet conduit 68 and inlet chamber 71 into cup 53.

An inlet valve assembly 92, is press-fitted or spot welded across the inside of cup 53. The inlet valve unit 92 (FIGURE 4) is formed by a supporting plate 94 having apertures 96 therethrough and supporting a valve stop member 98. A valve washer 180 is positioned between valve stop 98 and the upper surface of the valve support plate 94. The valve washer 100 extends over the inlet apertures 96 to prevent fuel flow downwardly (as shown in FIGURE 4) through the apertures 96 from the pumping chamber 25. A light spring 99 between the under surface of stop member 98 and the upper surface of Washer 100 biases washer in position on plate 94. An identical outlet valve assembly 102 is fixed across the inside of cup portion 54 to provide an outlet valve to the pumping chamber 25. The outlet valve assembly consists of similar parts shown for the inlet valve assembly 92 and includes an outlet valve washer 104. This specific valve structure shown is the subject of my co-pending application Serial Number 169,012, filed January 26, 1962, now Patent No. 3,198,128.

The open end of the cylindrical housing 16 is formed with a spiral corrugation shown at 79 to provide a screw threading to which is attached a similarly threaded upper rim 81 of a filter cup 80. The cup 80 is also formed of sheet metal and is deep drawn to form a housing for a filter assembly 82. Thus, plate 70 forms with the threaded end of housing 16 a housing portion which with the filter support cup 80 encloses and supports the filter element 82.

The bottom 72 of cup portion 54 abuts against the plate 70. Cup portion 72 is apertured and drawn into a collar 74 which extends through plate 70 to form an inlet fuel passage from the interior of cup 54 into the top of the filter housing.

The filter assembly 82 consists of an outer apertured cylinder 108 made, for example, of fiber board and having a large number of apertures 109 therethrough. A metallic cylinder 110 having apertures 111 therethrough is fixed coaxially within the center of the outer cylinder 108. Between the two cylinders is a paper filter element 112 consisting of a continuous endless strip of filter paper positioned in closely spaced folds extending btween the two

cylinders

108 and 110 and longitudinally with the axis of

cylinders

108 and 110. A pair of end plates 114 and 116 hold the two

cylinders

108 and 110 in their proper spaced relationship with the filter element 112 therebetween. The plates 114 and 116 are sealed to the

respective cylinders

108 and 110 so that fuel flowing from conduit 74 into cup 80 is forced to pass through the apertures 109, through the filter element 112 and into .the hollow center of the apertured cylinder 110. The filter element 82 has a washer 117 fitted tightly within a central aperture of the upper plate 114. This washer fits tightly over the end of an outlet conduit 118 and forms 4 a fuel tight seal between the filter element 82 and the conduit 118.

Fuel flowing through the passage 74 into the filter housing flows around the upper end plate 114 of the filter and through the apertured filter cylinder 108, the filter element 112 and through the apertured inner filter cylinder 110 to fill the space in the center of the filter defined by the cylinder 110. The outlet conduit 118 has one end extending through the gasket 117 closing the upper end of cylinder 110 as described. The other end 120 of the outlet conduit 118 extends upwardly and outward laterally, as shown in FIGURE 2. Conduit 118 extends between the two cup portions 53 and 54, as shown in FIGURE 1, as well as through the plate 70. The conduit 118 may be welded or brazed at the points it makes contact with plate and cups 53 and 54. The upper end 120 of conduit 118 is sealed by brazing to the wall of the pump housing 116. An outlet fitting 122 extends through an aperture in the wall of housing 16 and into the end 120 of the conduit, as shown in FIGURE 2. Fitting 122 forms means for attaching a fuel line 124.

The filter assembly 82 is replaceable by merely unscrewing the filter supporting cup from the threaded end of housing 16 and removing the filter element 82 from the gasket 117. A new filter unit 82 is slipped onto the gasket 117 and the filter cup 80 is screwed back onto the rim of the support cup 76. A rubber gasket ring 83 is positioned between a flanged portion of housing 16 and a channeled shoulder portion 87 at the rim of the supporting cup 80. Upon tightening the cup 80 to the housing 16, gasket 83 is tightly pressed between shoulder 85 and rim 87 to form a fuel-tight seal.

In operation, the upward stroke of diaphragm 22, as viewed in FIGURE 1, causes a sub-atmospheric pressure to be formed in the pumping chamber 25. This is reflected within the housing cup 53 and inlet chamber 71. Fuel will be pressed by atmospheric pressure from the tank 126 through an intake line 128 connected to the inlet conduit 68 leading into chamber 71. Fuel is sucked through the inlet valve assembly 92 into the pumping chamber 25.

On the downward stroke of rod 30, spring 44 presses the diaphragm 22 downwardly and forces the fuel through the outlet valve assembly 102 into the cup portion 54 and through conduit 74 into the filter assembly 82. Additional fuel flowing into the filter assembly 82 will fill the filter housing 80 and force fuel under pressure through the filter 112 and into the outlet conduit 118, the outlet fuel line 124 to a carburetor 130.

Fuel lines

124, 128 and carburetor 130 are schematically shown in FIGURE 1 with the carburetor mounted on the manifold 132 of engine 12. The construction and operation of carburetor 130 is not a part of this invention and thus is not described in detail. However, it may be assumed that the carburetor is of a conventional design and one in which air is pumped through an air filter 134 to mix with the fuel from line 124 within the carburetor 130.

Air and vapor passing through the fuel system to the carburetor becomes trapped in the upper region of the filter cup 80 as the paper filter element 112, when wet with fuel, prevents the passage of air therethrough. This trapped air and vapor provides a pulsation dampening air dome which absorbs the pulsations of the pump. The presence of such an air dome enclosing an air and vapor accumulation provides an air space into which fuel is forced under pressure on the pumping stroke and which, on the suction stroke, forces the fuel along the line to the carburetor. The space 115 within the filter eliminates the necessity of providing within the pump additional structure for trapping air to provide such a pulse dampening chamber. An air and vapor accumulation prevents the necessity of the pump on each stroke to move the relatively large amount of fuel between the outlet valve structure 102 and the carburetor mounted at some distance from the pump. Without such a dampening or pulse absorbing accumulation of vapor, an undue burden is put upon the pump and diaphragm 22. If the pump assembly is used in an upside-down position from that shown in FIGURE 1, the space 119 at the opposite end of cup 80 will trap air for pump dampening.

Carburetor 130 has an inlet valve which, when the carburetor fuel bowl is filled, closes off the line 124 to the carburetor. Since the engine continues to run, the rocker arm 36 will actuate the pumping diaphragm up-. wardly in an intake stroke. The downward stroke of the diaphragm under the urging of spring 44 will take place only as far as the fuel pressure within the line between the carburetor and fuel pump will permit. That is, on a downward stroke of diaphragm 22, the inlet valve 100 will close off the inlet line 128 and since fuel is also blocked in its flow to the carburetor, fuel pressure within the pumping chamber will retain the diaphragm in an upward position, and keep the spring 44 under tension. The forked end 34 of the lever 36 permits the oscillating movement of lever 36 to continue without affecting the pump until the carburetor inlet valve opens and the fuel pressure in the pump chamber relieved.

FIGURE 3 of the drawing shows a modification, and an alternate embodiment of the invention adapted for the utilization of a ceramic filter. Identical structures in FIGURE 3 to those in FIGURE 1 are represented by the same numbers, while similar structures are represented by the numbers of FIGURE 1 but primed. FIG- URE 3 shows a fuel pump in which the pump housing consists of a shortened plate-like configuration 139 having a pair of apertures through the bottom in which are sealed the lips of two cup-like structures 53' and 54'.

Pump housing 139 forms with the diaphragm 22, the pumping chamber 25 in the manner described and shown for structure of FIGURES 1 and 2. Inlet fitting 68 is sealed through the wall of cup structure 53' with inlet valve assembly 92 fixed between the inlet 68 and the pumping chamber 25. The portion, then, of cup structure 53' below the valve structure 92, forms an inlet chamber 71', as indicated.

Outlet cup 54' has the valve assembly 102 fitted at its upper open end, as indicated, forming an outlet chamber 75 within the remaining portion of cup 54. Outlet passage 74' is formed through the bottom of cup 54' from a flared collar portion fitted through the bottom of a filter support structure 140.

This support structure 140 is formed as a downwardly facing cup, the bottom of which is brazed or fastened by other appropriate means to the

pump cup portions

53' and 54. The rim of the filter support structure 140 is spirally corrugated, as indicated at 79' to receive a threaded upper rim portion 81' of the filter housing structure 142. This structure is formed of sheet metal and drawn into the cup-like configuration, to house and receive a ceramic filter cup 144 having a center reservoir for holding filtered fuel, in a coaxial nested relationship thereto.

The rim of ceramic cup 144 is urged tightly into sealing engagement with a flexible gasket member 150 Which is fitted snuggly around outlet conduit 118 and supported by a shallow dish plate structure 148 fixed to conduit 118 and support 140. A compression spring 146 biased between the bottom portions of filter housing 142 and filter cup 144, urges the rim of ceramic cup 144 against sealing gasket 150. A small magnet 152 is supported by a coiled wire in the filtered fuel reservoir, the ends of which wire are embedded in the gasket member 150, as shown to attract and hold any minute ferrous particles which might be carried in the fuel.

The arrangement of structures in FIGURE 3 enables rapid replacement of the ceramic filter cup 144 as needed. This is achieved by merely unscrewing the filter housing 142 from the filter support cup 140, removing the filter, and replacing it with a new filter and then attaching the housing 142 to the support 140. The rubber gasket 83 positioned between portions of the filter housing 142 and the support structure 140 provides a fuel-tight seal between these two members.

Operation of the pump and filter structure of 53 is similar to that described for FIGURES 1 and 2. Fuel from the pumping chamber 25 is forced through the valve structure 102 into the outlet chamber 175. Fuel passes on into the filter housing 142 and fills the space surrounding the ceramic filter cup 144. Fuel passing through the filter is forced upwardly past the magnet 152 and into the outlet conduit 118 from which it flows into the carburetor in a manner similar to that described for the structure in FIGURE 1. The purpose of small bar magnet 152 is to provide a magnetic filtering function which tends to remove magnetic or ferrous metallic particles from the fuel as it passes into the conduit 118.

The parts of the filter and pump structure shown in FIGURE 3 are again made entirely of sheet metal with relatively simple fabricating techniques and processes. The parts are those provided by drawings and stampings which lend themselves to a much more economical fabrication of the parts.

The fuel pump and filter assembly described is one which is made from easily formed and fabricated metal parts. These parts are those which are assembled by soldering, brazing, welding, or any desired and well known procedure. The thinness of the metal allows the fuel passing through both the pump and the filter portions of the assembly to be exposed to the cooling effect of ambient air. During the operation of the motor vehicle air will flow around the engine and the pump assembly to provide this cooling effect to the fuel in this pump and filter assembly.

Heat transfer through the sheet metal housing 16 and the filter cup is much greater than if these parts were formed of cast metal several times thicker, even though the cast metal were an aluminum alloy having a greater heat conductivity. These pump parts are all. exposed to the cooling effect of ambient air moving over their surfaces due to the movement of the vehicle or the fan 136 of the engine. Thus, the fuel pump is maintained at a lower temperature which minimizes vapor lock conditions. Such conditions exist when the engine is shut off for a period of time after a hot run. The heat of the engine builds up and by conduction and radiation to the fuel system heats the fuel in the fuel lines and the pump. Upon starting the engine, however, the flow of air past the pump quickly cools the pump parts to a lower temperature and reduces the vapor conditions in this part of the fuel system.

The thickness of the sheet metal pump and filter structures have been given above as being in the order of 0.030. However, the thickness need only to be sufficient to provide the required structural strength and rigidity for proper pump and filter operation. Such a thickness with sheet steel, for example, may range from 0.010 to 0.0625". Sheet metal of this thickness provides a greater cooling effect and pumps fabricated in the manner de scribed operate at lower temperatures than those made from thicker castings and with the described advantages. It would also be Within the scope of this invention to also form the pump spring housing 14 of sheet metal.

From the foregoing description it is clear that the presently described invention provides a device exhibiting greater utility both from the point of view of economics and also practicality. It is clear, however, to those skilled in the art that the presently described embodiment and the operation thereof may be altered slightly with-out departing from the spirit and scope of the invention as defined in the following claims.

I claim:

1. A fuel pump comprising:

(A) a spring housing having a rim at one end defining an opening,

(B) a diaphragm positioned across said opening and having :a peripheral edge fixed to said rim,

(C) an elongated cylindrical pump housing having opposed open and closed ends, said open end sealably engaging said rim of said spring housing to form a fuel inlet chamber,

(D) a diaphragm actuating means positioned in said spring housing including an elongated rod having one end attached to said diaphragm and having the other end engaging an operating lever,

(B) a first thin metal plate fixed across said pump housing and spaced from said diaphragm to define a pumping chamber,

(F) a plurality of thin walled cups depending from first thin metal plate into said fuel inlet chamber and opening into said pumping chamber, check valve means in each of said respective cups for controlling the fiow of fuel passing through said pumping chamber,

(G) a thin wall filter housing removeably connected to said pump housing and forming a filter chamber,

(H) a filter disposed in said filter chamber,

(1) at least one of said cups being in fluid communication with said fuel inlet chamber to receive fuel from the latter,

(I) another of said cups being communicated with said filter chamber for receiving fuel from the pumping chamber and passing the same to said filter compartment,

(K) an inlet conduit communicated with said fuel inlet chamber and adapted to connect to a source of fuel for circulating the latter in said fuel inlet chamber prior to the introduction of fuel to said at least one cup,

(L) discharge means communicated with said filter chamber for conducting fuel therefrom.

2. In a fuel pump as defined in claim 1 wherein said housing defines an annular chamber extending co-extensively with said spring housing and having a fuel inlet member in communication therewith.

3. In a fuel pump as defined in claim 1 wherein said thin Wall cup containing said outlet valve extends longitudinally to said fuel inlet chamber.

4. In a fuel pump as defined in claim 1 wherein said respective thin walled cup members are spaced one from the other and from said cylindrical pump housing to form passages therebetween to circulate incoming fuel.

5. In a fuel pump as defined in claim 1 wherein discharge means communicated with said filter chamber includes a conduit disposed in said fuel inlet chamber and transversing a wall of said cylindrical pump housing for carrying fuel from said filter chamber into heat transfer relation with fuel in said fuel inlet chamber.

References Cited by the Examiner UNITED STATES PATENTS 1,789,611 1/1931 Van Ranst 2104l6 2,840,002 6/ 1958 Elder et al.

2,842,267 7/1958 Shire et al. 210--416 2,969,745 1/1961 Johnson et al 103-150 2,997,180 8/1961 Loveday.

3,000,467 9/ 1961 Bowers.

3,000,506 9/ 1961 Hultgren.

3,039,485 6/ 1962 Bnohl.

3,076,550 2/1963 Wilhelm 210-438 X 3,082,875 3/1963 Korte 210-443 X 3,096,722 7/1963 Fitzgerald et a1 103-150 3,150,601 9/1964 Smith et a1. 103l50 3,161,142 12/1964 ReitZ 103150 REUBEN FRIEDMAN, Primary Examiner.

D. M. RIESS, Assistant Examiner.

Claims

1. A FUEL PUMP COMPRISING: (A) AN SPRING HOUSING HAVING A RIM AT ONE END DEFINING AN OPENING, (B) A DIAPHRAGM POSITIONED ACROSS SAID OPENING AND HAVING A PERIPHERAL EDGE FIXED TO SAID RIM, (C) AN ELONGATED CYLINDRICAL PUMP HOUSING HAVING OPPOSED OPEN AND CLOSED ENDS, SAID OPEN END SEALABLY ENGAGING SAID RIM OF SAID SPRING HOUSING TO FORM A FUEL INLET CHAMBER, (D) A DIAPHRAGM ACTUATING MEANS POSITIONED IN SAID SPRING HOUSING INCLUDING AN ELONGATED ROD HAVING ONE END ATTACHED TO SAID DIAPHRAGM AND HAVING THE OTHER END ENGAGING AN OPERATING LEVER, (E) A FIRST THIN METAL PLATE FIXED ACROSS SAID PUMP HOUSING AND SPACED FROM SAID DIAPHRAGM TO DEFINE A PUMPING CHAMBER, (F) A PLURALITY OF THIN WALLED CUPS DEPENDING FROM FIRST THIN METAL PLATE INTO SAID FUEL INLET CHAMBER AND OPENING INTO SAID PUMPING CHAMBER, CHECK VALVE MEANS IN EACH OF SAID RESPECTIVE CUPS FOR CONTROLLING THE FLOW OF FUEL PASSING THROUGH SAID PUMPING CHAMBER, (G) A THIN WALL FILTER HOUSING REMOVEABLY CONNECTED TO SAID PUMP HOUSING AND FORMING A FILTER CHAMBER, (H) A FILTER DISPOSED IN SAID FILTER CHAMBER, (I) AT LEAST ONE OF SAID CUPS BEING IN FLUID COMMUNICATION WITH SAID FUEL INLET CHAMBER TO RECEIVE FUEL FROM THE LATTER, (J) ANOTHER OF SAID CUPS BEING COMMUNICATED WITH SAID FILTER CHAMBER FOR RECEIVING FUEL FROM THE PUMPING CHAMBER AND PASSING THE SAME TO SAID FILTER COMPARTMENT, (K) AN INLET CONDUIT COMMUNICATED WITH SAID FUEL INLET CHAMBER AND ADAPTED TO CONNECT TO A SOURCE OF FUEL FOR CIRCULATING THE LATTER IN SAID FUEL INLET CHAMBER PRIOR TO THE INTRODUCTION OF FUEL TO SAID AT LEAST ONE CUP, (L) DISCHARGE MEANS COMMUNICATED WITH SAID FILTER CHAMBER FOR CONDUCTING FUEL THEREFROM.