Fuel Pumps With Reversible Air Dome And Filter

Abstract

A diaphragm type fuel pump is provided made of body castings with sheet ml stamped airdomes insertable in one of the cast bodies in such a position as to provide airdomes for inlet and outlet passages. One such airdome has incorporated therein a cylindrical filter element to effect a unitary airdome and filter cartridge or assembly. Airdomes and filters may be inserted in pumps of the invention positioned as determined by the mode of mounting of any such pump, i.e., whether the inlet and outlet conduits are above or below the pumping diaphragm when the pump is mounted on an engine.

Description

The invention relates to an improvement over assignee's prior patents issued to Claude F. Phillips, 3,370,543, and W. J. Hicks, 3,224,377. In the present invention, the airdomes are inverted cups as in the aforementioned patents and have differing lengths although still manufactured by sheet metal stamping. to

An airdome cup downstream of the outlet valve of the pump can accommodate a cylindrical filter spaced internally of the cup and of conventional construction such as pleated filter paper or equivalent structure. The filter element is longer than the airdome to provide exposure to fuel, and a spring biases the airdome and filter assembly against a removable body end cap to facilitate removal for replacement when the end cap is removed.

A detailed description of the invention now follows in conjunction with the appended drawing in which:

FIG. 1 is a longitudinal cross section in a vertical plane of a fuel pump incorporating the invention;

FIG. 2 is a section through 2--2 of FIG. 1, shown fragmentarily;

FIG. 3 is a plan view looking into the fuel section of the pump on the parting line 3--3 of FIG. 1;

FIG. 4 shows the airdome arrangement when the pump is mounted inverted, shown fragmentarily; and

FIG. 5 is a perspective of the airdome and filter cartridge or assembly.

Referring to FIGS. 1-3, a pair of cast body sections, lever section 10 and fuel section 15 having pump chamber are provided wherein the section 10 mounts a lever arm 18 (details of mount not shown) for upward pull on the diaphragm stem 22 against bias of spring 26, whereby diaphragm 30 is flexed upwardly for a suction stroke in the usual manner. Fuel enters through the inlet conduit nipple 33 secured in cast conduit channel 34 at the bottom of valve well 36, in fuel section 15, and via the vertical recesses or grooves 38 in the casting walls separated by ribs 43. The fuel passes around the cup of inlet airdome 50, to spacing 53 and thence to inlet valve 54 above the airdome. Spacing 53 is intermediate the top closed end of the airdome and the valve, as shown.

The airdome 50 has a frictional slide fit therein against projecting shoulders 55 on three of the ribs 43 with an intermediate screen disc 56. One side of the airdome can rest on the conduit channel 34 which is part of the casting, as seen in FIG. 1. The top ends of the ribs provide a seat for the ring base 58 of the valve unit 54. The ring base 58 is force fitted against the inner periphery surface of the well to seat against the top ends of ribs 43.

Valve unit 54 is a conventional component and need not be further described save to say that it is similar with the outlet valve unit 62 mounted in reverse position, all as commonly understood by persons familiar with the art.

The airdome 50 is a cup of stamped sheet metal or other suitable material mounted to be open at the bottom to effect air entrapment in the manner taught by the previously mentioned patents. The screen 56 is a mesh having a radial flange seating between a narrow inturned flange of the airdome and the rib shoulders. It has been found that the use of such a screen across the mouth of an airdome has certain beneficial aspects, e.g., as described in various prior art patents such as W. T. Tabb, 2,405,466, and F. G. Schweisthal, 1,809,394.

From the foregoing description it will be apparent that on the suction stroke fuel will pass through the opened valve 54 into pump chamber as the diaphragm 30 rises and upon the pressure stroke effected by force of spring 26, the valve 54 closes and the fuel then passes from the pump chamber to the discharge or outlet valve 62 forcing that valve to open whereby fuel then has entry into an outlet well 70 in which is disposed an open bottom airdome 75.

Airdome 75 is likewise a cup of stamped sheet metal or suitable material and formed with a socket 78 at its upper closed end wall for receiving the upper end of a cylindrical filter element 82 of conventional construction such as pleated paper, or the like, the other end of which cylindrical filter is socketed in a metal cap 86, which rests against a gasket 90, contiguous with a bored closure cap 93 threaded into the fuel section 15 to which is secured outlet nipple 93a.

Airdome 75 has an easy sliding fit in well 70 and vertical recesses or grooves 94 (FIG. 3) similar to recesses 38 are provided separated by ribs 95, the top ends of which form support surfaces or shoulders to seat the outlet valve 62, which is forced fitted within the well. A spring 96 is compressed between the valve cage and a depression 99 in the closed upper end of the airdome in order to insure retention of the filter cylinder between the socket 78 and socket 86 against the closure cap 93 via gasket 90.

Thus, by providing a sliding fit between airdome 75 and well 70, the filter cylinder may readily be changed by merely removing the end cap 93, spring 96 pushing the airdome and filter assembly as a unit (FIG. 5) out of the well so it can be readily grasped.

The airdome is foreshortened relative to the filter cylinder to provide a flow gap 102 for fuel flow from recesses 94, (FIG. 3).

From the foregoing description it will be apparent that flow through outlet valve 62 will pass downwardly through the recesses 94 longitudinally of well 70 past the exterior of the airdome 75 and to the filter cylinder 82 via gap 102. A concentric spacing 105, as shown, is provided between the interior walls of the airdome 75 and filter 82 to provide substantial flow area.

Accordingly, fuel flows through gap 102 rising upwardly in spacing 105 to the extent permitted by the pressure of air trapped in airdome 75, depending on engine operation conditions, and through filter 82 to the interior thereof, having egress via outlet nipple 93a.

Referring to FIG. 4, all essential components heretofore described are found therein and identical reference characters are used for identical parts. It will be noted that the pump has now been inverted and, accordingly, the airdome 50 is inverted with respect to the fuel section 15. The airdome 50 is, at the open end, spaced for fuel flow as by spacing 112, a small fraction of an inch, from the valve ring base 58, and seats at its upper or closed end against the shoulders of the ribs. The screen 66 can grip the ribs 43 frictionally around its periphery or be secured by spot soldering to the ribs, or suitably fastened to the airdome.

The outlet airdome 115 differs somewhat in shape from airdome 75, but has been inverted so that the closed end is disposed via the gasket 90 against the end cap 93. Spring 117 maintains the assembly of an end socket 120, filter cylinder 82 and airdome 115 as a unit, whereby removal of end cap 93 will permit the spring to push the airdome and filter assembly out of the well sufficiently so that it can be grasped and removed, for replacement of the filter cylinder.

The unit comprising the airdome, filter and socket 120 can be cemented together or fastened by crimping to effect and integral replacement unit, if desired.

Claims

I claim:

1. A fuel pump comprising body means having a fuel section provided with a well and fuel passage ingress means connected thereto; an airdome removably inserted in said well, passage means in said well effecting communication of fuel to said airdome at an open bottom end thereof to effect air compression therein; a filter element in said airdome and said filter element having a spacing from the walls thereof to provide fuel communication between said open bottom and an upstream side of said filter element within said airdome; and fuel passage egress means connected to conduct fuel from a downstream side of said filter element out of said well.

2. A fuel pump as set forth in claim 1, said airdome having a closed end and slidably being insertable with said closed end uppermost in said well; spring means in said well having a removable end of said airdome and said airdome and said well having a removable end cap, said spring means biasing said airdome towards said end cap, said airdome being spaced at said open bottom from said end cap by said filter element; said airdome being foreshortened relative to said filter element to provide access of fuel to said filter element and into the spacing between said filter element and said airdome and into said airdome; said filter element being restrained by said end cap against bias of said spring means; whereby removal of said end cap permits said spring means to at least partially eject said filter element from said well for removal and replacement.

3. A fuel pump as set forth in claim 1, said filter element having a hollow center and said well being closed at one end and having an outlet conduit connected thereto open to the hollow center of said filter element; said well being closed by a valve at the other end openable by fuel pressure in the course of pumping; the walls of said well being provided with recess means to permit flow of fuel around said airdome from said valve to the open bottom end thereof.

4. A fuel pump as set forth in claim 1, an end of said well being provided with outlet means for fuel flow connection downstream of said filter element; an opposite end of said well being provided with a valve openable by pumping pressure; walls of said well having grooves encompassing said airdome, said airdome being shorter then said filter element so as to provide a gap for passage of fuel from said grooves to said filter element and to the spacing between said filter element and said airdome whereby fuel passing said valve can flow past the sides of said airdome and have access through said filter element to the interior thereof and thence to said outlet means.

5. A fuel pump as set forth in claim 1, including an additional well in said fuel section, an airdome in said additional well, a valve in said additional well and secured therein and a spacing between said airdome and said valve; the walls of said additional well having groove means encompassing said airdome and effecting passage therepast for fuel flow to said spacing and thence to said valve; said airdome having a substantially open bottom end; inlet means for effecting ingress of fuel into said well at said open bottom, said inlet means connecting with said groove means.

6. A fuel pump comprising body means having a fuel section having an inlet well and an outlet well, each of said well having walls provided with grooves for fuel flow around an airdome in each well and including an airdome in each well laterally located by radially disposed ridges between grooves; a valve in each well seatingly supported on the ends of the ridges therein, including means effecting ingress of fuel to one well and egress from the other well; and means for pumping fuel from the inlet well through the valve thereof to the outlet well through the valve thereof.

7. A pump as set forth in claim 6 said valves comprising base rings force fitted in respective wells and a filter element within the airdome of the outlet well and communicating with the grooves thereof.

8. A fuel pump as set forth in claim 7, said outlet well having an airdome removable from said well upon removal of an end cap; and a spring in said well biasing said outlet airdome and filter element towards said end cap to effect at least partial ejection thereof from said well when said end cap is removed.