US3096722A - Fuel pump - Google Patents

Description

J. B. FITZGERALD EI'AL 3,096,722

FUEL PUMP Filed Aug. 17, 1961 July 9, 1963 INVENTOR. JOHN B. FITZGERALD DONALD RCOMPTON BY AGENT 3,096,722. FUEL PUMP John B. Fitzgerald, St. Louis, Mo., and Donald R. Compton, Belleville, Ill., assignors to ACE Industries, Incorporated, New York, N.Y., a corporation of New Jersey Filed Aug. 17, 1961, Ser. No. 132,134 14 Claims. (Cl. 103-150) This invention relates to fuel pumps and particularly to a diaphragm pump suitable for pumping fuel to an internal combustion engine.

In an automotive vehicle the fuel pump is normally mounted either on or adjacent to the engine mounting and at some distance from the fuel tank which is normally positioned at the opposite end of the vehicle. A fuel inlet line extends from the fuel tank to the inlet chamber of the fuel pump. Also the carburetor in an automobile is normally mounted above the upper surface of the engine block and above the fuel pump position. A fuel line extends from the outlet of the pump upwardly to the inlet of the carburetor.

During engine operation, the reciprocating action of the pump diaphragm sucks fuel through the inlet line to the pump from the fuel tank and forces fuel through the outlet line of the pump into the carburetor. The fuel in the line between the pump and the fuel tank consists substantially of a long column of liquid having an inertia which must be overcome when the diaphragm sucks the fuel through the inlet line and which must be resisted when the fuel in the inlet line is suddenly .stopped by the closing of the inlet valve each time the pump starts. a pumping stroke. Also, the fuel in the outlet line of the pump extending to the carburetor contains a column of fuel which is moved rapidly upward and then stopped with the closing of the outlet valve each time the diaphragm reverses itself and goes into a suction stroke. The inertia of the fuel in this outlet column must be overcome upon each movement of the fuel upwardly and upon the stopping of the fuel each time the outlet pump valve closes.

The pump diaphragm of the fuel pump in an automotive vehicle is reciprocated backwards and forwards through the pumping and suction strokes from 250 times a minute to 2,000 times per minute. At high speed, the inlet valve and the outlet valve must be opened and closed at these same rates. Simultaneously the column of fuel in the inlet conduit leading to the pump from the fuel tank and the column of fuel in the outlet line leading from the pump to the carburetor must be moved and stopped in their motion with the same frequency. It has been found that with an engine operating at high speed, the valves of the pump cannot operate efiiciently to open and close at these high frequencies. Accordingly, pulsation chambers or vapor domes have been formed in the pump to dampen the rapid pulsations of the pump so that the fuel in the inlet and outlet conduits to the pump is moved more continuously, and only the fuel adjacent to the inlet and outlet valves of the pump need to be reciprocated at the pumping frequencies. This allows proper functioning of the inlet and outlet valves of the pump since they are not now subject to the inertia of the moving fuel columns as they would be without the dampening chambers.

Fuel pumps fabricated from sheet metal do not easily lend themselves to the provision of dampening chambeis for the purposes described. One design is in the use of atent o" 3,096,722 Patented July 9, 1963 special elements within the inlet and outlet portions of a sheet metal pump, which trap air and fuel vapors for dampening the pump pulsations in the respective fuel lines.

It is therefore an object of this invention to provide in a fuel pump a novel structure providing pulsation dampening chambers.

It is another object of this invention to provide novel structure forming a means for trapping air and vapor in a fuel pump to provide pulsation dampening.

In general these objects are accomplished by providing within each of the inlet and outlet chambers of a fuel pump a generally spool-shaped element.

The spool-shaped element forms with the pump housing a pulsation dampening chamber and has a mesh screen fixed across the access to fuel to retain the vapors within the chamber.

In the accompanying drawings, in which one of several of various possible embodiments of the invention is illustrated,

FIG. 1 is a view in elevation illustrating a diaphragm pump of this invention in use on the'engine of an automotive vehicle for pumping fuel from the fuel tank of the vehicle to the carburetor for the engine, the pump being an inverted pump;

FIG. 2 is a vertical section of the pump shown in FIG. 1, and

FIG. 3 is a horizontal section taken on line 33 of FIG. 2.

Corresponding reference characters indicate corresponding parts throughout the several views of the drawings.

Referring to FIG. 1 of the drawings, there is indicated at A an automotive vehicle having an engine E on which is mounted a fuel pump P of this invention. Fuel is delivered from fuel tank T of the vehicle through a line L1 to the fuel pump P and delivered by the latter through a line L2 to the carburetor C for the engine. The carburetor is mounted on the intake manifold of the engine, and an air filter F is shown mounted on the air horn of the carburetor.

As appears in FIGS. 1-3, pump P is a so-called inverted pump, i.e., its inlet and outlet are located at the bottom of the pump. As shown in detail in FIGS. 2 and 3, pump P comprises a rocker arm housing 1 which is open at one end (its left end as appears in FIG. 2), this end being referred to as the inner end of the housing. This housing is of generally rectangular form in vertical cross section and of decreasing height from its inner end to its outer end (which is closed). At its inner end it has a flange 3 for attaching it to the engine E. A rocker arm 5 is pivoted at 7 in the housing for rocking motion on a horizontal axis transverse to the housing. Arm 5 has a portion 5a projecting out of the open inner end of the housing, and is biased to rock clockwise as viewed in FIG. 2 by a spring 9. When the pump is mounted on the engine, the free end portion 5a of the rocker arm is engaged by an engine-driven eccentric or cam 11. On rotation of the cam through half a revolution from its FIG. 2 position (wherein the low point of the cam engages portion 5a of the rocker arm), the rocker arm is rocked counterclockwise from its FIG. 2 position against the bias of spring 9. The latter is adapted to return the arm clockwise during the succeeding half-revolution of the cam.

Extending downward from the rocket arm housing 1 at its outer end is a hollow conical pump head 13. An opening 15 is provided between the interior of housing 1 and the hollow head 13 at the top of the latter. The conical head has an outwardly projecting fiat 17 at the bottom. The bottom of this rim constitutes a seating surface for the margin of an annular diaphragm 19 consisting of a relatively thin disk of flexible fuel-resistant material, such as a suitable synthetic rubber, which, when in unstressed condition, is flat or substantially flat. The outer margin of the diaphragm is clamped against the bottom of rim 17 by a pump body 21 which, as illustrated in FIG. 2, is of one-piece thin-walled sheet metal construction, formed of shallow cup shape, having a bottom or end wall 23 and a flaring, rounded annular peripheral wall 25 defining a pumping chamber 26, with an outwardly extending annular flat flange 27 at the top of Wall 25, and a cylindric rim 29. The body 21 is maintained in assembly with head 13 by spinning or crimping the. rim 29 over on rim 17 of the head as indicated at 31, with the margin of the diaphragm clamped between rim 17 and flange 27 under suificient pressure to provide a fuel-tight seal all around the margin of the diaphragm.

The diaphragm is adapted to be pulled or'flexed upward by a diaphragm-actuating rod 33 and to be flexed downward by a spring 35. Rod 33 extends upward through head 13 and through the opening 15 at the top of the head into the rocker arm housing 1. The rocker arm has a slot 37 at its end in housing 1 receiving the rod 33. The latter has a collar 39 at its upper end engageable by this end of the arm 5. The rod extends slidably through an oil seal and rod guide 41 held in an annular recess at the top of the head 13 by the reaction on a seal retainer ring '43 of the spring 35, this spring being a coil compression spring surrounding the rod. The diaphragm is mounted on the lower end of the rod 33 between a pair of circular plates 45 and 47, plate 45 being the upper plate and plate 47 the lower plate. The upper plate is formed with an annular corrugation or rib 49 forming a seat for confining the lower end of spring 35. The upper plate is of larger diameter than the lower plate and the margin of the upper plate which overhangs the lower plate is flared outward and downward to provide a rim 51 constraining the diaphragm to have an annular, free, nonreversing loop 53. The lower plate has a curved rim 55 engaging the loop. In the downward position of the diaphragm illustrated in FIG. 2, the outside of the loop engages the rounded flaring Wall 25 of the pump body 21. When arm 5 is rocked counterclockwise by cam 11, it lifts the rod and pulls the diaphragm upward. This loads the spring 3 5. Then when arm 5 rocks clockwise, spring 35 is adapted to drive the diaphragm and rod downward.

The sheet metal pump body 21 is formed with two integral deep-drawn rounded-bottom cylindrical cup- shaped projections 57 and 59 extending downward from the bottom wall 23 of the body 21 on opposite sides of the center of the bottom wall. Projection 57 defines an inlet passage or intake cavity 61 and projection 59 defines an outlet passage or discharge cavity 63. An inlet nipple 65 is provided at the lower end of projection 57, and an outlet nipple 67 is provided at the lower end of projection 59. It will be understood that, in the installation shown in FIG. 1, supply line L1 is connected to inlet nipple 65 and discharge line L2 is connected to outlet nipple 67. An intake check valve 69 is provided in the upper end of the intake cavity 61 and a discharge check valve 71 is provided in the upper end of the discharge cavity 63. Nipple 65 provides for connection of supply line L1 to intake cavity 61 upstream from the intake check valve 69 and nipple 67 provides for connection of discharge line L2 to the discharge cavity 63 downstream from the discharge check valve 71. These check valves are of identical construction and may be of a type well-known in the fuel pump art, each comprising a valve seat 73 and a mushroom head 87 on a stem extending from the valve seat, with a spring surrounding the stem and pressing a disk valve member toward the seat, but preferably are of a type such as shown in the copending coassigned application of Russell F. Smith et al., Serial No. 122,025, filed July 5, 1961. The seats are press-fitted in the cavities with the valves positioned reversely in respect to one another so that intake valve 69 opens upward and discharge valve 71 opens downward.

Fitted in each cavity below the respective valve is a sheet metal member generally designated 91 comprising a tubular stem 93 and a flaring head 95 on the upper end of the stem. The cavities are of such height as to accommodate both the valves and the members 91. Head 95 has a cylindric rim 97 dimensioned for a press fit in the cavity. Each member 91 is arranged axially in its respective cavity, being pressed down in the cavity to a point where the lower end of the tubular stem 93 is spaced somewhat above the bottom of the cavity. A screen 99 is provided in the intake cavity 61 at the lower end of stem 93 in the intake cavity, and a screen 101 is provided in the discharge cavity 63 at the lower end of the stem 93 in the discharge cavity. As shown, screen 99 is of flat cir cular form with a center hole 103 receiving the lower end of the stem 93 in the intake cavity and has a cylindric rim 105 having a press fit in the intake cavity. Screen 101 is also of fiat circular form with a cylindric rim 107 having a press fit in the discharge cavity, but does not have a center hole. It will be understood that in the manufacture of the pump the screens are fitted in the cavities through the open ends of the cavities at the bottom of body 21 first, then members 91 are fitted in the cavities, then the valves are fitted in the cavities, after which the body 21 and diaphragm are assembled with the head 13 on the rocker arm housing 1.

Each member 91 forms an annular chamber 109 around stem 93. Each chamber constitutes a dome in which fuel vapor (as distinguished from liquid fuel) may be trapped, and is in communication with the lower end of the respective cavity through the interstices in the respective screen 99 or 101. Each screen may be a woven wire screen preferably of from 60-70 mesh, although this may be varied.

The pump valves 73 are spring biased into a closed position. The inlet valve 73 to the pump is only opened because of fuel under atmospheric pressure in the fuel tank T and the inlet conduit L1 forces the inlet valve open as the pump goes through a suction stroke. The outlet valve of the pump is opened against its biasing spring and the weight of fuel in conduit L2 by the force of fuel in the pumping chamber against the pump valve as the pump reverses and goes into a pumping stroke. During the suction stroke of the pump, the fuel in the fuel line L1 is moved so that some of the fuel flows into the pumping chamber of the pump. Upon the quick reversal of the pump diaphragm in direction to form a pumping stroke, the moving fuel in the inlet line L1 must be stopped and the valve closed so that the fuel in the pumping chamber can be forced through the outlet rather than back through the inlet. During this pumping stroke the column of fuel L2 is set in motion so that fuel is forced upwardly into the carburetor. During the suction stroke of the pump, the column of fuel in the outlet line L2 is substantially stationary because of the closed outlet valve, while during the pumping stroke, the line of fuel in the inlet line L1 is substantially stationary because of the closing of the inlet valve to the pump. During rapid reciprocation of the pump at higher engine speeds, the stopping and starting of these lines of fuel presents somewhat of a problem and it has been found that at very high speeds of pump reciprocation, the inlet and outlet valves of the pump cannot operate successfully because of the inertia of the moving columns of fuel. However, with the use of the dampening or pulsation chambers 109 established in the pump, the pulsations are dampened to an extent that fuel flow in the lines L1 and L2 becomes slower and continuous and only the fuel adjacent to the valves 71 goes through a rapid starting and stopping cycle. This, then, permits the closing springs of the inlet and outlet valves to operate as intended, since there is much less inertia of the fuel immediately adjacent to the valve.

On demand for fuel from the carburetor, diaphragm 19 is flexed up and down by the action of cam 11 and spring 35. On an upward (suction) stroke of the diaphragm, the intake check valve 69 opens and the discharge check valve 71 closes, and fuel is drawn into the pumping chamber 26 below the diaphragm. On a downward (discharge) stroke of the diaphragm, the intake check valve 69 closes and the discharge check valve 71 opens, and (fuel is forced out through line L2 to the carburetor C. Fuel vapor and air, if any, in the fuel are trapped in the annular chambers or domes 109, entering these chambers via the interstices in the screens. The fuel vapor and air trapped in these annular chambers or domes 109 are compressible, consequently the chambers 109 serve as standpipes or surge chambers tending to reduce pulsations in pressure of the fuel and to increase the rate of delivery of fuel by the pump to the carburetor in comparison with a pump not equipped with such chambers for trapping fuel vapor and air and utilizing such trapped vapor and air for damping pulsation. The tubular stems 93 of members 91 act as conduits for flow of fuel, the annular surge chambers 109 surrounding these conduits. The use of a surge chamber is particularly important as regards the discharge side of the pump, and in some instances it may not be necessary to use a surge chamber at the intake side. However, use of a surge chamber at the intake side in addition to the surge chamber at the discharge side ordinarily adds to the eifectiveness in reduction of pulsation.

The screens serve the purpose of effectively trapping the gaseous bubbles of fuel vapor and air in the surge chambers 109 without impeding rise and fall of the level of liquid fuel in the surge chambers as occurs with pulsations in pressure. In this respect, it is to be observed that the pressure required to force the vapor and air through the interstices of the screens is higher than the pressure required to force liquid fuel through the interstices of the screens. This appears to be due to the surface tension of the bubbles of fuel vapor and air in the surge chambers and/or to the tendency of liquid fuel to cling within the interstices of the screens due to surface tension of the liquid fuel, thereby tending to block How of fuel vapor and air downward and out of the surge chambers. In any event, the screens tend to hold the fuel vapor and air bubbles within the surge chambers at maximum bubble volume, and this assures maximum pulsation-damping efficiency. At the same time there is no substantial impedance to flow of liquid fuel up into or down out of the bottoms of the surge chambers. It is also to be observed that there is no requirement for accurate positioning of members 91 and the screens in the cavities, which simplifies the assembly operation.

In view of the above, it will be seen that the several objects of the invention are achieved and other advantageous results attained.

As various changes could be made in the above constructions without departing from the scope of the invention, it is intended that .all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.

We claim:

1. A diaphragm pump comprising a body formed to provide a pumping chamber, an intake cavity and a discharge cavity each in communication at one end With the pumping chamber, a diaphragm closing the pumping chamber, the intake cavity having an intake check valve therein and being adapted for connection of a supply line thereto upstream from the intake check valve, the

discharge cavity having a discharge check valve therein and being adapted. for connection of a discharge line thereto downstream from the discharge check valve, means in the discharge cavity forming a fuel outlet conduit and a surge chamber around said conduit and forming a fuel passage between said surge chamber and said discharge cavity, and a screen in said discharge cavity across said fuel passage to trap gas in said surge chamber.

2. A diaphragm pump as set forth in claim 1 wherein said means is located downstream from the discharge check valve.

3. A diaphragm pump as set forth in claim '1 further comprising means in the intake cavity forming a fuel inlet conduit and a second surge chamber around said inlet conduit and forming a fuel passage between said second surge chamber and said intake cavity, and a second screen in said intake cavity across said last named fuel passage to trap gas in said second surge chamber.

4. A diaphragm pump as set liorth in claim 3 wherein said means in the discharge cavity is located downstream from the discharge check valve and said means in the intake cavity is located upstream from the intake check valve.

5. A diaphragm pump as set forth in claim 1 wherein said discharge cavity extends downward from the pumping chamber and said means is located in said discharge cavity below the discharge check valve.

6. A diaphragm pump comprising a cup-shaped sheet metal body having a bottom wall and a peripheral wall defining a pumping chamber and having a pair of cupshaped projections extending down from its bottom Wall defining an intake cavity and a discharge cavity opening into said pumping chamber, a diaphragm closing the pumping chamber, the intake cavity having an intake check valve therein and being adapted for connection of a supply line thereto upstream from the intake check valve, the discharge cavity having a discharge check valve fitted therein and being adapted for connection of a discharge line thereto downstream from the discharge check valve, a member comprising a tubular stem and a head on the upper end of the stem arranged axially in the discharge cavity downstream from the discharge check valve wit-h the head closing off the portion of said discharge cavity therebelow and defining an annular surge chamber in said discharge cavity around said stem, and a screen in said discharge cavity at the lower end of said stem.

7. A diaphragm pump as set forth in claim 6 further having a member comprising a tubular stem and a head on the upper end of the stem arranged axially in the intake cavity upstream from the intake check valve with the head closing off the portion of said intake cavity therebelow and defining an annular surge chamber in said intake cavity around the stem in said intake cavity, and a screen at the lower end of the stem in said intake cavity.

8. In a pump for pumping liquid having a pumping chamber and a generally vertical cavity extending from said pumping chamber, means in said cavity including a conduit defining an annular surge chamber around said conduit and extending axially in said cavity, and a screen in said cavity at the lower end of said chamber of such mesh as to trap gas in said chamber.

9. In a pump as set forth in claim 8, said conduit comprising a tubular stem and a head on the upper end of the stem fitted in the cavity, said screen being located at the lower end of the stem.

10. A fuel pump comprising a body enclosing a pumping chamber, a cavity and a fuel passage connecting said cavity to said pumping chamber, a tubular member within said cavity and having one end flared outwardly from the axis of said member and extending across said cavity to the wall thereof, the periphery of said flared end being fixed to said cavity wall to form a surge chamber between said tubular member and said cavity wall, a mesh screen mounted across said cavity in a position spaced from said flared end to partially close said surge chamber, said screen being of such mesh when wet with fuel to trap gas in said surge chamber. y

11. The invention of claim 10 wherein said screen is positioned at the other end of said tubular member.

12. The invention of claim 10 wherein said screen extends across the other end of said tubular member.

13. The invention of claim 10 wherein said screen is fitted between said cavity wall and the other end of said tubular member to close said surge chamber between said 10 ends of said tubular member.

14. The invention of claim 10 wherein the other end of said tubular member extends through said screen and is fixed thereto, and the periphery of said screen is fixed to said cavity wall.

References Cited in the file of this patent UNITED STATES PATENTS 1,809,394 SchWeiSthal June 9, 1931 1,897,292 Babitch Feb. 14, 1933 2,929,333 Harry Mar. 22, 1960

Claims (1)

1. A DIAPHRAGM PUMP COMPRISING A BODY FORMED TO PROVIDE A PUMPING CHAMBER, AN INTAKE CAVITY AND A DISCHARGE CAVITY EACH IN COMMUNICATION AT ONE END WITH THE PUMPING CHAMBER, A DIAPHRAGM CLOSING THE PUMPING CHAMBER, THE INTAKE CAVITY HAVING AN INTAKE CHECK VALVE THEREIN AND BEING ADAPTED FOR CONNECTION OF A SUPPLY LINE THERETO UPSTREAM FROM THE INTAKE CHECK VALVE, THE DISCHARGE CAVITY HAVING A DISCHARGE CHECK VALVE THEREIN AND BEING ADAPTED FOR CONNECTION OF A DISCHARGE LINE

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