US3096721A - Fuel pump - Google Patents

Description

July 9, 1963 J. M. WHITE ETAL 3,096,721

FUEL PUMP Filed Aug. 14, 1961 2 Sheets-Sheet 1 INVENTOR. J AC K M. WHITE LDON A. JOHNSON B M AGENT July 9, 1963 J. M. WHITE ETAL 3,096,721

FUEL PUMP Filed Aug. 14, 1961 2 Sheets-Sheet 2 #l/II'IIIIIIII' INVENTOR. JACK M. WHITE BY ELDON A.JOHNSON AGENT rates This invention relates to fuel pumps and particularly to a diaphragm pump suitable for pumping fuel to an internal combustion engine.

Pumps of the type used to pump fuel from a fuel tank to the carburetor of an internal combustion engine conventionally comprise a diaphragm pumping element driven through a lever system by the engine of the vehicle. The diaphragm constitutes one Wall of a pumping chamber, in an opposite Wall of which are positioned inlet and outlet Valves for causing the fuel to move through the pumping chamber as the diaphragm is reciprocate-d. 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 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 engine speed. At high speed, the inlet valve and the outlet valve ust be opened and closed at this same rate. 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 pup cannot operate efficiently 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.

A more recent approach to the fabrication of automotive fuel pumps is the use of sheet metal in forming the atent O 3,096,721 Patented July 9, 1963 various pump housing structures. This results in an economy of fabrication since the sheet metal can be worked with less expensive techniques than required with a metal casting. The problem, however, is also in the fabrication of dampening chambers in a sheet metal pump which is designed for economy and with a minimum number of parts.

Accordingly, it is an object of this invention then to provide a fuel pup fabricated from sheet metal having a novel structural arrangement providing fuel pump pulsation dampening chambers within the pump housing.

It is a further object of this invention to provide a novel structure for a fuel pump which provides a pulsation dampening chamber adjacent to the inlet and outlet valves of the fuel pump.

It is a further object of this invention to provide an inexpensively fabricated fuel pump for an automotive engine having pulsation chambers adjacent to the inlet and outlet valves of the pump and formed of a minimum nuber of parts.

The invention coprises essentially a fuel pump for an automotive engine in which a portion of the fuel pump comprises a housing structure fiabrioaltedil {from sheet metal. This housing structure forms one wall of the pumping chamber of the pump in which the diaphragm of the pup forms a movable second wall. The sheet metal housing structure includes a pair of tubular extensions projecting from the pumping chamber and in one there is mounted an inlet valve assembly and in the other there is mounted an outlet valve assebly. Within each of the tubular extensions and adjacent to the respective valve structures there is formed an annular pulsation or pulsation dampening chamber. The chamber is formed from a spool-like metal element coaxially mounted within each tubular extension and having access to the flow of fuel respectively into the pump or outward from the pump. Air and fuel vapors are trapped within the dampening chambers to form a gaseous bubble in each chamber for minimizing the effect of the pump pulsations on the fuel coluns entering and leaving the fuel pump.

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, this pump being of a type that may be referred to as an inverted P p;

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

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

FIG. 4 is a horizontal section taken on line 4-4 of FIG. 2;

FIG. 5 is a vertical section illustrating a second pump of this invention, being of a type that may he referred to as an upright pump; and

FIG. 6 is a horizontal section taken on line 6-6 of FIG. 5.

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

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 rocker 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 flat rim 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 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 sufficient 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 5 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 5'1 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 35. 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 cupshaped projections 57 and 5% extending downwardly 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. To 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 trom 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, each comprising a valve sea-t 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 72 toward the seat. Valves of this type are shown in the copending coassigned application of Russell F. Smith et 211., Serial No. 122,025, filed July 5, 1961. Intake valve 69 opens upwardly and discharge valve 71 opens downwardly.

A generally spool-shaped member 91, which may be formed of any appropriate sheet metal or plastic or other material, is fitted in the cylindrical projections 57 and 59 below the respective valve, the projections being of such height as to accommodate both the valves and the members 91. It will be understood that in the manufacture of the pump, members 91 are fitted in the projections respectively through their open ends. Then, a valve 71 is fitted in the cavity of each projection respectively, after which the body 21 and diaphragm are assembled with the head 13 on the rocker arm housing 1. Each member 91 has a tubular stem portion 93 and upper and lower flaring end heads 95 and 97. Each head 95 has a cylindrical rim $8 dimensioned for a press fit in the cavity of the projection. Heads 97 are of generally square roundedacorner outline as shown in FIG. 4, with their diagonal dimension somewhat less than the internal diameter of the projection cavity. Each member 91 is pressed down in the respective cavity to the point where the rounded corners of its head 97 engage the rounded bottom of the respective cavity, and thereby forms an annular chamber 99 around stem 93 in restricted communication with the lower end of the cavity through the spaces such as indicated at 101 in FIG. 4 between the straight sides of the head 97 and the rounded bottom of the cavity. Each chamber 9 constitutes a dome in which fuel vapor (as distinguished from liquid fuel) and air may be trapped.

The pump valves 72 are spring biased into a closed position. The inlet valve 72 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 99 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 99. The fuel vapor and air trapped in these annular chambers or domes 9-9 are compressible, consequently the chambers 99 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 stem portions 93 of the spool-shaped members 91 act as conduits for flow of fuel, the annular surge chambers 99 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 effectiveness in reduction of pulsation.

The flared heads 97 tend to prevent entrainment of fuel vapor and air in the surge chambers 99 in liquid fuel flowing through the passages or cavities 61 and 63 such as otherwise might occur due to turbulence, and thus serve to maintain vapor and air trapped in these cavities to accomplish their intended function.

FIGS. 5 and 6 illustrate a pump P1 which is a socalled upright pump, i.e., its inlet and outlet are located at the top rather than at the bottom, and in which means different from than the spool-shaped members 91 of the pump P shown in FIG. 2. is used to provide the surge chambers in the intake and discharge cavities. Pump P1 is essentially simply an inversion of pump P, but, as appears in FIG. 5, the inlet and outlet nipples, which are designated 65a and 67a, have extensions such as indicated at 111 projecting axially into the respective cavities 61 and 63. Each nipple extension has a sheet metal member 113 secured to the end thereof within the respective cavity, this member 113 having a flaring conical head 115 at one end of a tubular stem 117 which has a press fit on the nipple extension. Each head 115 flares outward and dovmward from the lower end of the respective nipple extension, and its diameter at its lower (and larger) end is smaller than the internal diameter of the respective cavity to provide an annular space 119 around the head providing for restricted communication between the portion of the cavity below the head and the annular space 121 around the nipple extension above the head. This space 121 constitutes a dome or surge chamber in which fuel vapor (and air) may be trapped, which functions in a manner similar to chambers 99 of pump P of FIG. 2 to damp pulsations in pressure of fuel. The nipple extensions act as conduits for flow of fuel, the annular surge chambers 12]. surrounding these conduits.

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 cup-shaped sheet metal body having an end and a peripheral wall defining a pumping chamber and having a pair of cup-shaped projections extending from its end wall defining an intake cavity and a discharge cavity respectively 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, and means comprising a tubular stem and a head on the stem arranged axially in the discharge cavity downstream from the discharge check valve providing an annular surge chamber around the tubular stem in the discharge cavity.

2. A diaphragm pump as set forth in claim 1 further having means comprising a second tubular stem having a head arranged axially in the intake cavity upstream from the intake check valve providing an annular surge chamber around said second tubular stem in the intake cavity.

3. A diaphragm pump as set forth in claim 1 wherein the pump is arranged with the cavities extending downward from said pumping chamber, and wherein said head is located at the upper end of the stem and is fitted in said discharge cavity to constitute the top of said surge chamber.

4. A diaphragm pump as set forth in claim 1 wherein said head is at one end of said stem with space around said head for restricted communication between the surge chamber and the portion of the discharge cavity below said head.

5. A diaphragm pump as set forth in claim 1 wherein the pump is arranged with the cavities extending down Ward from said pumping chamber, and further having means comprising a second tubular stem having a head on said second stem arranged axially in the intake cavity upstream from the intake check valve providing an annular surge chamber in said intake cavity, the head of each means being located at the upper end of the respective stemand being fitted in the respective cavity to constitute the top of the respective surge chamber.

6. A diaphragm pump as set forth in claim 5 wherein each means includes a second head at the lower end of the respective stem thereof with space around each said lower head for restricted communication between the re spective surge chamber and the portion of the respective cavity below each said lower head.

7. A diaphragm pump as set forth in claim 1 wherein the pump is arranged with the cavities extending upward from said pumping chamber, and wherein said head is located at the lower end of the stem with space around said head for restricted communication between the surge chamber and the portion of the discharge cavity below said head.

8. A diaphragm pump :as set forth in claim 1 wherein the pump is arranged with the cavities extending upward from said pumping chamber, and further having means comprising a second tubular stem having a head on said second stem arranged axially in the intake cavity upstream from the intake check valve providing an annular surge chamber around the tubular stem in the intake cavity, the head of each said means being located at the lower end of the respective stem with space therearound for restricted communication between the respective su-rge chamber and the portion of the respective cavity therebelow.

9. In a pump for pumping liquid comprising a pump body provided with a generally vertical passage for flow of liquid, a member having a tubular stem portion and heads at the ends of said stem portion arranged axially in said passage, the upper head on said stem portion closing oil the portion of the passage therebelow and defining an annular surge chamber in said passage around said tubular stern portion, the lower head on said stem portion being formed for restricted communication between said chamber and the portion of said passage therebelow.

10. In -a pump for pumping liquid having a pumping chamber and a cavity extending upward firom said prnnping chamber, a tube extending downward into said cavity, and a head on said tube within said cavity defining an annular surge chamber within said cavity around the portion of the tube in said cavity, said head being formed for restricted communication between said chamber and the portion of said cavity therebelow.

11. A pump comprising a body having a pumping chamber and an outlet cavity extending from said pumping chamber, an outlet valve assembly fixed between said pumping chamber and said outlet cavity, and a tubular element forming an outlet passage within said outlet cavity and sealed at one end to the outlet cavity wall to form a surge chamber therebetween, said tubular element having a head at the other end thereof, said head flaring outwardly from the axis of said tubular element towards said outlet cavity wall and forming with said outlet cavity wall a restricted passage for communication between said surge chamber and said outlet passage.

12. The invention set forth in claim 11 wherein said one end of said tubular element comprises an annular portion extending outwardly from the axis of said tubular element between said outlet valve assembly and said other tubular element end, said annular end portion being sealed at its periphery to said outlet cavity Wall.

13. The invention set forth in claim 11, wherein said head is positioned between said outlet valve assembly and said one end of said tubular element.

References Cited in the file of this patent UNITED STATES PATENTS 1,897,292 Babitch Feb. 14, 1933 1,944,340 Zubaty et a1 Jan. 23, 1934 2,018,150 Rockwell Oct. 22, 1935 2,957,420 Reynolds et a1 Oct. 25, 1960

Claims (1)

1. A DIAPHRAGM PUMP COMPRISING A CUP-SHAPED SHEET METAL BODY HAVING AN END AND A PERIPHERAL WALL DEFINING A PUMPING CHAMBER AND HAVING A PAIR OF CUP-SHAPED PROJECTIONS EXTENDING FROM ITS END WALL DEFINING AN INTAKE CAVITY AND A DISCHARGE CAVITY RESPECTIVELY 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, AND MEANS COMPRISING A TUBULAR STEM AND A HEAD ON THE STEM ARRANGED AXIALLY IN THE DISCHARGE CAVITY DOWNSTREAM FROM THE DISCHARGE CHECK VALVE PROVIDING AN ANNULAR SURGE CHAMBER AROUND THE TUBULAR STEM IN THE DISCHARGE CAVITY.

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