US3368495A

US3368495A - Fuel feed system and fuel pump

Info

Publication number: US3368495A
Application number: US525605A
Authority: US
Inventors: Robert K Turner
Original assignee: Tillotson Manufacturing Co
Current assignee: Tillotson Manufacturing Co
Priority date: 1966-02-07
Filing date: 1966-02-07
Publication date: 1968-02-13
Anticipated expiration: 1985-02-13

Description

Feb. 13, 1968' R. K. TURNER FUEL FEED SYSTEM AND FUEL PUMP 4 Sheets-Sheet 1 Filed Feb. 7, 1966 mp K d d w L m 5 1w w, y w, 2 k w w a a 2 Feb. 13, 1968 R. K. TURNER 3,368,495

FUEL FEED SYSTEM AND FUEL PUMP Filed Feb. 7, 1966 4 sheets-Sheet 2 fFJ 151 Feb. 13, 1968 R. K. TURNER 3,363,495

FUEL FEED SYSTEM AND FUEL PUMP I Filed Feb. 7, 1966 4 Sheets-Sheei 5 INVENTOR. POBEAT K TURNER I Arrow/5y Feb/13, 1968 R. K. TURNER 3,368,495

FUEL FEED SYSTEM AND FUEL PUMP Filed Feb. 7, 1966 4 sheets-sheet 4 v [J9]! 65" mg; 56 INVENTOR.

ROBE/PT A TU/P/VE/P JAM/ 01M- ATTORNEY United States Patent 3,368,495 FUEL FEED SYSTEM AND FUEL PUMP Robert K. Turner, Toledo, Ohio, assignor to The Tillotsou Manufacturing Company, Toledo, Ohio, a corporation of Ohio Filed Feb. 7, 1966, Ser. No. 525,605

11 Claims. (Cl. 103152) ABSTRACT OF THE DISCLOSURE The invention embraces a fuel feed system embodying a fuel pump construction having a flexible pumping diaphragm actuated by varying fluid pressure, the pump being equipped with a fuel inlet flap valve arrangement wherein fluid pressure for actuating the diaphragm is utilized to exert pressure upon the fuel inlet valve of the pump to force the inlet flap valve toward'closed position on a fuel delivery movement of the pumping diaphragm and to assist in opening movements of the fuel inlet valve during suction movements of the pumping diaphragm.

This invention relates to fuel feed system and fuel pump and more especially to a fuel feed system embodylng a fuel pump associated with a charge forming apparatus wherein the fuel pump is of the diaphragm type incorporating a pumpingdiaphragm actuated by varying fluid pressures, such as the varying pressure in the crankcase of a two cycle engine with which the fuel feed system and pump may be used.

Diaphragm fuel pumps having a fluid-pressure actuated diaphragm have come into extensive use for pumping fuel from a tank to a carburetor employed with two cycle engines wherein the pumping diaphragm is actuated or vibrated by fluid pressures in the engine crankcase. In most installations utilizing a diaphragm type pump, the pump construction is secured to a carburetor bOdy to provide a compact construction as well as to facilitate transmission of fluid pressure pulsations from the engine crankcase to the pumping diaphragm through channels in the carburetor body in communication with the engine crankcase through an opening in the mounting flange of the carburetor thereby obviating the use of an external tube means connecting the pumping or pulsing chamber with the engine crankcase.

Diaphragm pumps of this character usually embody valve flaps or valve means formed integrally with the diaphragm for controlling inlet and outlet ports in the fuel pump in order to deliver fuel from a fuel supply or tank to the inlet region of the carburetor. A pump of this general character is shown in Phillips Patent 2,796,838. While the flap valve means made integral with the diaphragm provides an inexpensive valve means for controlling liquid fuel flow through the pump, under certain operating conditions the inlet valve, being of a highly flexible material, does not always seat properly and the eificiency of the pump is thereby impaired. Another difficulty encountered with this type of inlet valve is in starting an engine. When starting an engine by usual cranking procedure where the fuel tank is disposed below the carburetor, eflicient lifting ability of the pump at cranking speed is essential in order to deliver fuel to the carburetor. If the inlet valve is not effectively seated in closed position, fuel from the fuel chamber of the pump will flow in a reverse direction past the improperly seated inlet valve to the fuel tank. This condition renders it diificult to start the engine.

The invention embraces a fuel feed system embodying a fuel pump construction having a flexible pumping diaphragm actuated by varying fluid pressure, the pump embodying a fuel inlet valve arrangement wherein fluid 3,368,495 Patented Feb. 13, 1968 pressure for actuating the diaphragm is utilized to exert pressure upon the fuel inlet valve of the pump in valve closing position to assure eifective closing of the valve and thereby improve the pumping efficiency.

Another object of the invention resides in a diaphragm fuel pump construction for delivering fuel to a charge forming apparatus wherein the pumping diaphragm is operated by varying fluid pressure, the fuel inlet valve of the pump being of a flap type and the latter associated with a flexible membrane which is subjected to varying fluid pressure whereby pulse pressure is eifective on the membrane to force the inlet flap valve to closed position on a fuel delivery movement of the pump diaphragm, the membrane being under the influence of reduced pressure periods to enhance or assist in opening movements of the fuel inlet valve and thereby increase the fuel delivery capacity of the pump.

Another object of the invention is the provision of a diaphragm pump embodying a fuel inlet valve for the pump and a flexible impervious means adjacent the pump inlet valve wherein pressure pulsations developed in the crankcase of an engine with which the fuel pump is utilized are effective to exert pressure on the flexible means to close the fuel inlet valve providing a seal effective to prevent reverse flow of fuel through the inlet port and thereby provide for easy starting of the engine by reason of positive delivery of fuel to the charge forming apparatus by the fuel pump.

Another object of the invention is the provision of a diaphragm type fuel pump embodying a flap type inlet valve for a fuel inlet port in combination with a pressure responsive means to assure more effective closing of the inlet valve during pump operation and wherein means is provided adjacent the inlet port and the valve to facilitate fuel flow past the inlet valve when the same is opened and thereby improve the fuel delivery capacity of the pump.

Further objects and advantages are within the scope of this invention such as relate to the arrangement, operation and function of the related elements of the structure, to various details of construction and to combinations of parts, elements per se, and to economics of manufacture and numerous other features as will be apparent from a consideration of the specification and drawing of a form of the invention, which may be preferred, in which:

FIGURE 1 is a top plan view of a combined charge forming apparatus and fuel pump arrangement of the fuel feed system;

FIGURE 2 is a front elevational view of the combined charge forming apparatus and fuel pump of FIG- URE 1;

FIGURE 3 is a longitudinal sectional view through the charge forming apparatus and fuel pump of the fuel feed system, the view being taken substantially on the line 3-3 of FIGURE 1;

FIGURE 4 is a transverse sectional view taken substantially on the line 44 of FIG. 3;

FIGURE 5 is a schematic sectional view illustrating the components of the fuel pump arrangement;

FIGURE 6 is a fragmentary isometric view illustrating the fuel inlet valve and a fuel passage compartment adjacent thereto;

FIGURE 7 is an enlarged sectional view of a portion of the fuel pump construction showing the fuel inlet valve in closed position;

FIGURE 8 is a sectional view similar to FIGURE 7 illustrating the fuel inlet valve in open position;

FIGURE 9 is a plan view of a member embodying integral inlet and outlet valves of the fuel pump;

FIGURE 10 is a bottom plan view of one of the body sections of the pump construction;

FIGURE 11 is an enlarged detailed sectional view sim- 3 ilar to FIGURE 7 illustrating a modified form of fuel inlet valve and pumping diaphragm arrangement showing the inlet valve in closed position;

FIGURE 12 is a sectional view similar to FIGURE 11 illustrating the fuel inlet valve in open position;

FIGURE 13 is a plan view of the diaphragm and valve construction shown in FIGURE 11; and

FIGURE 14 is a view similar to FIGURE 7 illustrating a modified form of the invention.

While the fuel feed and charge forming apparatus is illustrated particularly for use with an engine of the two cycle or two stroke type, it is to be understood that the fuel feed system of the invention may be utilized with other types of internal combustion engine where pulsating fluid pressures are available.

Referring to the drawings in detail, FIGURES 1 through 4 illustrate a charge forming apparatus or carburetor and fuel pump arrangement of the fuel feed system of the invention for delivering fuel and air mixture into the crankcase of a two cycle engine of the internal combustion type, the system including a carburetor component or charge forming apparatus and a fuel pump construction 12.

The carburetor or charge forming component 10 of the fuel feed system is inclusive of a carburetor body 14 formed with a mixing passage 16, the mixing passage including a Venturi 18 having a choke band or restricted region 20 of conventional construction.

The mixing passage of the carburetor is provided with an air inlet region 22. An air valve or choke valve 24 is disposed in the air inlet region or passage 22, the valve being supported upon a rotatable shaft 25 which is journaled in bores formed in the body 14, the valve 24 providing a conventional choke means for reducing air flow through the mixing passage for engine starting purposes. An arm 26 is secured to the shaft 25 for manipulating the air or choke valve 24. The opposite end of the carburetor body is fashioned with a mounting flange 28 adapted to be secured to a boss portion formed on a wall of the crankcase 30 of an engine of the two cycle type.

A member 31 provided with conventional reed valves (not shown) is positioned between the mounting flange 28 and the crankcase 30, the carburetor body being secured to the engine crankcase by securing bolts 32. The mixing passage 12 is fashioned with a mixture outlet region 34 in which a throttle valve 36 of the disc type is mounted on a rotatable shaft 37 journaled in suitable bores formed in the body 14 of the carburetor. Secured on one end of the throttle shaft 37 is a manipulating means 38 for operating the valve, the opposite end of the throttle shaft 37 being equipped with an arm 39 engageable with a screw 40 for adjusting the engine idling position of the throttle valve 36.

In the embodiment illustrated, the fuel pump includes

pump body sections

44 and 46 supported by the carburetor body 14, the pump being hereinafter described in detail. The carburetor body is fashioned with a comparatively shallow unvented fuel chamber 50, a flexible impervious diaphragm 52 forming a wall of the fuel chamber 50 has its peripheral portions disposed between the pump body section or member 44 and the carburetor body 14, a gasket 54 being disposed adjacent the periphery of the diaphragm 52.

A main fuel delivery outlet, orifice or passage 56 opens into the Venturi and is adapted to deliver fuel from the fuel chamber 50 into the mixing passage under aspiration or reduced pressure in the mixing passage for normal and high engine speeds, the delivery orifice 56 being in communication with the fuel chamber 50 by passage means of conventional construction (not shown), provided in the carburetor body. A high speed fuel adjusting needle valve 58, a portion of which is shown in FIG- URE 1, is associated with the fuel passage means for adjusting fuel flow to the main nozzle or orifice 56.

As shown in FIGURE 3 the carburetor body is fashtoned with a supplemental chamber 60 in communication with an engine idling orifice 62 and a low speed orifice 64 opening into the mixing passage adjacent the throttle valve 36, one wall of the chamber 60 being provided by a Welch plug 66. The supplemental chamber 60 receives fuel through passageways (not shown) in a conventional manner from the fuel chamber 50.

The fuel passage arrangement between the fuel chamber 50 and the supplemental chamber 60 is provided with a low speed fuel adjusting valve 68, a portion of which is shown in FIGURE 1.

The fuel passage means for the main orifice for the engine idling and low speed orifices and the adjustable needle valves for regulating fuel flow through the passage means is of the character illustrated in Phillips Patent 3,090,608. The fuel chamber 50 in the carburetor body is fashioned with an elongated recess 70 accommodating a lever 72 fulcrumed upon a pin 73. The diaphragm 52, herein referred to as a metering diaphragm, is provided at its opposite sides with metal or plastic discs 74 and 75 secured to the diaphragm by a headed member or rivet 80.

The head of the member is adapted for operational engagement with the long arm of the lever 72. An expansive coil spring 82 disposed close to the fulcrum pin 73 is in engagement with the long arm of the lever 72. Threaded into a bore in the carburetor body is a sleeve or tubular fitting 84 in which is slidably disposed a valve body or member 86 of polygonally-shaped cross section to facilitate flow of liquid fuel along the facets of the valve body.

The valve body 86 has a cone-shaped valve portion 88 which cooperates with an annular member 90 providing a port 91 through which liquid fuel flows into the fuel chamber 50. The short arm 77 of the lever 72 engages the lower end of the valve body 86 as shown in FIGURE 4.

The region of the fuel inlet port 91 in the carburetor is supplied with fuel from the fuel pump construction 12 through connecting

passageways

93, 94, 95 and 96 from the fuel pump.

During engine operation, suction or aspiration in the mixing p:ssage 16, communicated to chamber 50 through the fuel passage means, causes upward flexure of the metering diaphragm 52, as viewed in FIGURE 4, moving the lever 72 about its fulcrum in a counterclockwise direction to permit movement of the needle valve 88 away from its seat to admit fuel into the fuel chamber 50 for delivery through the passage means and orifices into the mixing passage.

The expansive coil spring 82 normally exerts pressure on the lever 72 slightly greater than fuel pressure from the fuel pump to maintain the needle valve 88 normally closed so that the valve is only opened under engine aspiration or reduced pressure in the mixing passage to deliver fuel into the chamber 50.

The pump body section or component 44 is fashioned with a recess or chamber 100 at the opposite side of the flexible diaphragm 52 to facilitate flexure of the diaphragm, the dry chamber 100 being vented to the atmosphere through connecting

passages

102 and 104.

As the relative position of the inlet valve 88 in the carburetor is controlled by aspiration in the mixing passage influencing the position of the diaphragm 52, it is found that a balance is substantially maintained whereby the rate of flow of liquid fuel past the valve 88 is substantially equal to the rate of delivery of fuel from the chamber 50 into the mixing passage 16, the control valve 88 being in slightly open position during most of the period of engine operation.

The fuel pump body sections or

members

44 and 46 are secured to the carburetor body 14 by means of screws disposed in aligned openings in the pump body members and extending into threaded openings in the carburetor body. Secured to the body component 46 is a closure member 112 engaging a gasket 114, member 112 being secured to the body section 46 by a screw 116 threaded into an opening in a boss portion 117.

A filter screen 118 is disposed between the gasket 114 and a circular ledge on the body component 46 for filtering incoming fuel from a supply into the chamber 120, shown in FIGURES 3 and 4. The closure member 112 is fashioned with a nipple portion 122, shown in FIG- URE 2, connected with a fuel tank or other fuel supply through a tubular means or hose 123.

- The

pump body sections

44 and 46 are respectively provided with

concave recesses

126 and 128 forming a cavity, and extending across the cavity and between the

sections

44 and 46 is a flexible pumping diaphragm 130 which may be of rubber-like material or resinous plastic, the recess 126 being a pumping chamber and the recess 128 being a fuel receiving chamber of the pump construe-- tion.

With particular reference to the schematic sectional view of FIGURE 5, the diaphragm 130 has a peripheral portion disposed between the peripheral regions of the

pump body members

44 and 46.

The pump body section 46 is fashioned with a fuel inlet port 134 in communication with the fuel chamber 120 adjacent the filter screen 118. The body section 44 is fashioned with a compartment or space 136 above an inlet valve 148 in pump component 44, as shown in FIG- URES 5, 7 and 8, to provide clearance space for opening movement of the inlet valve. The fuel receiving chamber 128 of the pump is in communication with an outlet port 138 in the pump body section 46, the pump body section 44 being fashioned with a recess 151 to accommodate opening movements of the pump outlet valve 150.

In the form shown in FIGURES 5 through 10, a member 142 of flexible material is disposed contiguous with portions of the diaphragm 130 and is configurated with spaces or

cutaway regions

144 and 146 providing respectively the inlet flap valve 148 and an outlet flap valve 150. The

flap valves

148 and 150 are formed integral with the member 142, the flap valves adapted for hinging action at the regions of the integral connection of the flap valves with member 142. As shown in FIGURES 5 through 8, the inlet flap valve 148 is disposed adjacent the fuel inlet port 134, the compartment or space 136 facilitating opening movement of the inlet valve 148.

The outlet flap valve 150 is disposed adjacent the fuel pump outlet port 138, a clearance space or recess 151 in member 44 accommodating opening movement of the valve 150 facilitating fuel delivery from the fuel receiving chamber 128 of the pump into the

passageways

96, 95, 94 and 93 to the region of the fuel inlet valve 88 in the carburetor body 14. The pumping chamber 126 above the diaphragm 130, as viewed in FIGURES 1, 2 and 4, is in communication with the crankcase of the engine through interconnecting

passageways

152, 153 and 154, the passage 154 extending through the mounting fiange 28 and is in registration with an opening in the wall of the crankcase 30.

In this manner, the varying fluid or gas pressure in the crankcase arising by reason of the reciprocations of the engine piston is communicated to the pumping chamber 126 to effect flexing movement or pumping movement of the pumping diaphragm 130 to pump fuel from the supply through the fuel receiving chamber 128 to the region of the inlet valve of the carburetor.

The present invention provides a system or method of utilizing varying fluid pressure developed in the engine crankcase in a manner to provide for more positive closing of the fuel inlet valve 148 with the occurrence of pressure pulses in the pumping chamber 126 and to relieve pressure on the inlet valve 148 on the suction or reduced fluid pressure cycles in the chamber 126. On opening movement of the inlet flap valve 148, fuel flows from the port 134 past the valve through connecting

passages

158 and 160 into the fuel receiving chamber 128 of the pump.

As particularly shown in FIGURES 7 and 8, the membrane portion 162 as shown in FIGURES 5, 7 and 8. Themember 142, shown in FIGURE 9, is provided with a circular opening 143, the opening being adjacent the pumping region of the pumping diaphragm between the pumping chamber 126 and the fuel receiving chamber 128 so that the pumping portion of the diaphragm 130 has unimpeded freedom of flexure or pumping movement by reason of the open area 143 in the member 142.

The diaphragm portion or membrane means 162 at the region of the compartment or recess 136 is imperforate and therefore isolates or separates the compartment 136 from the port 134 and the fuel passage 158. A feature of the system includes the communication of varying fluid pressure, which actuates the pumping region of the diaphragm 130, to the compartment or recess 136 for influencing the action or operation of the inlet flap valve 148. As particularly shown in FIGURES 5, 7 and 8, a passage or duct 166 connects the passage 152 with the compartment or chamber 136 adjacent the inlet valve whereby the diaphragm means or membrane portion 162 is subjected to the varying fluid pressures transmitted to the pumping chamber 126.

A pressure pulse from the engine crankcase effects movement of the pump components and movement of liquid fuel as follows: The pressure on the pumping portion of the diaphragm 130 flexes the diaphragm downwardly to the position indicated in FIGURE 7. Concomitantly the same pressure pulse is effective in the recess or compartment 136 to exert pressure upon the diaphragm portion or membrane 162 forcing the latter against the upper surface of the inlet flap valve 148 and thereby forcing or pressing the valve to seat on the flat or seat portion 149, as shown in FIGURE 7.

Fluid pressure is thus exerted on the inlet flap valve 148 to effectively close the inlet port 134 to prevent leakage or flow of liquid fuel in a reverse direction through the port 134 which would occur if the valve 148 is not tightly closed during a pressure stroke of the pumping portion of the diaphragm 130. By effectively closing the inlet valve 148, the pressure stroke of the diaphragm 130 is more effective to force fuel from the fuel chamber 128 through the outlet port 138 past the outlet flap valve 150 to deliver fuel to the region of the inlet valve 88 of the carburetor through the

interconnetcing passages

96, 95, 94 and 93 shown in FIGURE 4.

A pressure pulse is followed by a suction or reduced pressure condition set up by reduced pressure in the engine crankcase, the suction or reduced pressure being transmitted to the pumping diaphragm 130, flexes or moves the pumping portion of the diaphragm 130 upwardly to the position shown in FIGURE 8. This establishes a suction or reduced pressure condition in the fuel chamber 128 which closes the outlet valve 150 and opens the inlet valve in the manner shown in FIGURE 8.

The-reduced pressure or suction from the engine crankcase effective to elevate or flex the diaphragm 130 upwardly is likewise effective to elevate or flex the membrane or diaphragm portion 162 upwardly in the compartment or recess 136 to the position illustrated in FIGURE 8. At the same time the increased volume in the fuel chamber 128 resulting from upward flexure of the diaphragm 130 effects fuel flow from the supply throughout the inlet port 134 as the inlet flap valve 148 is opened to the position shown in FIGURE 8 assisted by removal of fluid pressure on the diaphragm portion or membrane 162 whereby fuel flows past the inlet flap valve 148 through

passages

158 and 160 into the fuel receiving chamber 128 of the pump construction.

This action is repeated with each pressure pulse and succeeding reduced pressure or suction cycle or condition established in the engine crankcase by reason of the piston movement of the engine. By reason of the suction or reduced pressure effective to elevate the diaphragm or membrane portion 162 to the position shown in FIGURE 8, such movement or differential pressure on opposite sides of the diaphragm means or membrane 162 assists in opening the inlet valve 148 and thereby further improving the pumping efliciency of the pump construction by facilitating the flow of increased volume of fuel past the opened valve 148.

FIGURE 6 illustrates the provision of a supplemental U-shaped compartment, chamber or recess in the pump body member 46 to further reduce resistance to flow of liquid fuel past the inlet flap valve 148 when the latter is in open position.

The recess 170 is of generally U-shaped configuration having elongated regions 171 adjacent the side edges of the inlet flap valve 148. Thus, when the inlet flap valve 148 is in open position, as shown in FIGURE 8, the fuel moving upwardly through the inlet port 134 flows past the valve 148 in radial directions into the elongated regions or recesses 171 of the U-shaped recess 170 as well as into the portion of the recess 170 adjacent the passage 158.

Through this arrangement, the resistance to flow of liquid fuel past the inlet valve 148 is reduced thereby promoting the flow of an increased amount of fuel past the inlet valve at each suction or reduced pressure stroke of the pumping diaphragm 130. Through the arrangement illustrated in FIGURES 1 through 10, a fluid pressure actuated means is disposed adjacent the inlet valve whereby during closed position of the inlet valve 148, pressure is exerted thereon to effect a positive or more perfect closure to thereby prevent flow of liquid fuel from the fuel chamber 128 in a reverse direction into the inlet port 134 of the fuel supply arrangement.

During a suction or reduced pressure condition in the pumping chamber 126, the differential pressure at opposite sides of the diaphragm means or membrane portion 162 elevates the same as shown in FIGURE 8 to facilitate opening movement of the inlet valve 148, the recess 170 and elongated recesses 171 thereof reducing resistance to fuel flow past the inlet valve to the fuel receiving chamber 128.

This feature is not only effective to increase fuel delivery capacity of the pump during engine operation but the arrangement performs an added function. During a cranking operation in starting the engine, each pressure pulse from the engine crankcase exerts pressure upon the diaphragm means or membrane portion 162 to seal the inlet flap valve on its seat so that effective lifting of fuel, even under the slow cranking action of starting the engine, is attained as liquid fuel from the fuel chamber 128 is prevented from leaking into the inlet port 134 because the inlet valve 148 is tightly held on its seat by fluid pressure.

FIGURES 11 through 13 illustrate a modification of the arrangement wherein the inlet and outlet flap valves are formed integrally with the pumping diaphragm and the fluid pressure actuated diaphragm means or membrane provided in a member disposed adjacent the inlet flap valve for exerting pressure on the inlet flap valve when the latter is moved to port-closing position. In this form the pump body sections 44' and 46' are of the same construction as hereinbefore described.

The pumping diaphragm 180 of flexible material, shown in FIGURE 13, is fashioned with an inlet flap valve 182 and an outlet flap valve 184 integral with the diaphragm 180. The inlet flap valve 182 is adapted, in closed position, to seat against the flat surface 149 of body section 46 in the same manner as hereinbefore described in the form shown in FIGURES through 8.

Disposed contiguous with the flap valve 182 and the adjacent mating portions of the pump body sections 44', but not extending across the pumping chamber 126, is an impervious flexible diaphragm means or member 183.

The flap valve 182 controls fuel flow through the inlet port 134 which, when the inlet valve is open, is in communication with the fuel receiving chamber 128' by connecting passageways 158' and The pump body section 44 is fashioned with a compartment, chamber or recess 136' adjacent the inlet flap valve 182 to facilitate opening movement of the valve and upward fiexure of the diaphragm means or membrane 183. A gasket is disposed between the pump body section 44' and the diaphragm except that the member 165 has openings at the regions of the pumping chamber 126, the recess 136' and a recess adjacent the pump outlet flap valve so that only the diaphragm 180 extends across the cavity provided by the pump chamber 126 and the fuel receiving chamber 128'.

In operation, a fluid pressure pulse from the engine crankcase is communicated through the passageways 152' and 153' to the pumping chamber 126, the latter being adjacent the pumping portion of the diaphragm 180. The pressure pulse is also communicated through the passage 166' to the chamber or compartment 136', exerting downward pressure upon the diaphragm means or membrane 183 which forces or presses the inlet valve 182 tightly on its seat 149' preventing leakage or flow of liquid fuel in a reverse direction through the port 134.

Thus, the pressure stroke or movement of the diaphragm downwardly positively forces fuel from the fuel chamber 128' past the outlet flap valve 184, shown in FIGURE 13, and through the connecting

passages

96, 95, 94 and 93, shown in FIGURE 4, to the region of the carburetor inlet valve 88. Each fluid pressure pulse is succeeded by a suction or reduced pressure condition established by reduced pressure in the engine crankcase, the suction or reduced pressure, being transmitted through

passages

152 and 153 to the pumping chamber 126', causes an upward flexure or suction stroke of the portion of the diaphragm 180 at the pumping chamber 126 to the position shown in FIGURE 12.

concomitantly the suction or reduced pressure is effective through the passage 166 and space 136 to flex the portion of the flexible diaphragm means or membrane 183 adjacent the inlet valve 182 upwardly in the compartment 136' as viewed in FIGURE 12. The increased volume in the fuel chamber 128 established by upward fiexure of the portion of the diaphragm 180 adjacent the pumping chamber 126' results in reduced pressure in the fuel receiving chamber 128 causing the inlet valve 182 to open and admit fuel from the supply through the port 134' past the opened inlet valve 182 and through the passages 158' and 160 into the fuel receiving chamber 128.

As the diaphragm means or flexible membrance 183, adjacent the inlet flap valve 182, is elevated by suction or differential pressure to the position shown in FIGURE 12, the diaphragm means 183 assists in the opening of the valve 182 and does not inhibit the opening movement thereof.

In the form of construction shown in FIGURES 11 through 13, the pumping diaphragm 180 and the inlet and

outlet valves

182 and 184 are fashioned of a single member, the flap valves being tongue portions provided by the cutaway regions or spaces 186 shown in FIG- URE 13.

The pumping diaphragm and the inlet and outlet valves are of the same material, which may be comparatively thin, flexible rubber-like material or a flexible woven or unwoven fabric impregnated with a thin synthetic rubber coating to render the diaphragm material impervious.

The diaphragm means or membrane 183 is of comparatively thin, highly flexible rubber-like material to be readily responsive to the varying fluid pressures set up or established in the chamber or compartments 136 to minimize the resistance of the material to flexure in order to obtain rapid response to high frequency fluid pressure variations so that the valve 182 may be readily opened and closed at high engine speeds and assuring effective closure of the inlet port 134' by the flap valve 182 during each fluid pressure pulse exerting pressure on the diaphragm means or membrane 183.

FIGURE 14 is an enlarged sectional view similar to FIGURE 11 illustrating a modified form of the invention. The arrangement is'inclusive of pump body components 44" and 46", of the same general character as the corresponding components shown in FIGURE 11.

The component 44" is fashioned with a pumping chamber 126" which is in communication with the engine crankcase by means of connecting passages 152" and 153". The pump body section or component 46" has an inlet port 134" and connecting passages 158" and 160" in communication with the fuel receiving chamber 128".

The pumping diaphragm 180 is of the same character as the diaphragm 180, shown in FIGURE 11, and has in integral inlet flap valve 182" and an outlet flap valve of the character shown at 184 in FIGURE 13. Disposed above the diaphragm 1 80" at the regions of mating surface portions of the body sections 44" and 46" is a gasket 165". Disposed between the gasket 165," and body section 44 is a diaphragm means or membrane 183 which functions in the same manner as the diaphragm means or membrane 183, shown in FIGURE 11.

In this form of the invention the gasket 165" is dis- .posed between the pumping diaphragm 180" and the diaphragm means or membrane 183", the latter extending across the compartment 136" and being impervious at this region. The compartment or chamber 136", which accommodates opening movement of the inlet flap valve 182", is in communication with the passages 152", 153" and the pumping chamber 126" through a passage 166 whereby varying fluid pressures from the engine crankcase are transmitted to the pumping chamber 126 and the compartment or chamber 136".

In this form of construction wherein the gasket 165" is disposed between the pumping diaphragm 180" and the membrane or diaphragm means 183", when pressures are equalized in the chamber 136" and the fuel chamber 128", the diaphragm means or membrane 183", which is of flexible material, extends across the space 136" and is spaced from the inlet valve 182" to the extent of the thickness of the gasket 165". The gasket 165" may be of a thickness of from about ten thousandths of an inch to forty thousandths of an inch, the usual thickness being about twenty thousandths of an inch.

- In operation, a fluid pressure pulse from the engine crankcase is communicated through passageways 152" and 153 to the pumping chamber 126" forcing the pumping portion of the diaphragm 180 downwardly as shown in FIGURE 14. The same pressure pulse is communicated to the compartment or chamber 136" through the passageway 166" exerting pressure on the diaphragm means or membrane 183" forcing the latter downwardly to the position shown in FIGURE 14 exerting pressure on the fuel inlet valve 182 to positivel seat the inlet valve on its seat or surface 149". This action provides a positive closure for the fuel inlet port 134" during a pressure stroke of the diaphragm 180" and prevents flow of fuel from the fuel chamber 128" in a reverse direction through the port 134".

Upon a succeeding suction or reduced pressure condition established by reduced pressure from the engine crankcase, the pumping portion of the diaphragm 180" is flexed upwardly and the diaphragm means or membrane 183 is flexed upwardly a substantial distance to accommodate opening movement of the inlet flap valve 182" in the same manner as the form of the invention shown in FIGURE 12.

Under a suction or reduced pressure condition in the chamber 136", the membrane 183" is elevated a substantial distance above the inlet valve 182 so as to provide a substantial open area between the inlet valve and its seat to facilitate fuel flow from the inlet port 134" past the inlet valve and into the fuel receiving chamber 128" and thereby providing high efficiency of fuel flow past the inlet valve 182" under suction or reduced pressure conditions in the pumping chamber 126 and the compartment 136".

While the U-shaped recess is illustrated in broken lines in FIGURE 14, it is to be understood that the arrangement shown in FIGURE 14 may be employed with or-without the recess 170" depending upon. the volume of liquid fuel transfer desired from the port 134" to the fuel receiving chamber 128".

It will be apparent that the invention provides a fuel feed system and method for utilizing varying fluid pres sure derived from an engine crankcase for establishing pressure upon a fuel inlet flap valve of a fuel pump in a manner to assure positive closure of the inlet valve upon a fuel delivery stroke or movement of the pumping diaphragm, and provide ample area when the inlet valve is opened for efficient fuel flow past the opened inlet valve so as to improve the pumping efficiency at all engine speeds as well as to prevent leakage or reverse flow of liquid fuel through the pump inlet port during hand cranking operations in starting the engine.

It is apparent that, within the scope of the invention, modifications and different arrangements may be made other than as herein disclosed, and the present disclosure is illustrative merely, the invention comprehending all variations thereof.

I claim:

1. A fuel feed system including in combination, pumpmg means for pumping liquid fuel from a supply to a charge forming apparatus including a pump body construction formed with a cavity, flexible means disposed across the cavity providing a pumping chamber and a fuel chamber, said pumping chamber arranged for'communication with a source of varying fluid pressure for actuating the flexible means to establish successive pump? ing impulses in said fuel receiving chamber, inlet and outlet ports for conveying fuel into and away from the fuel receiving chamber, inlet and outlet flap valves of flexible material for said ports, a second cavity in the pump body construction adjacent the inlet valve, flexible means extending across said second cavity providing a pressure chamber, and passage means for transmitting the varying fluid pressure to the pressure chamber to influence. the flexible means in the second cavity to engage and bias the inlet flap valve toward closed position during valve closing movements.

2. In combination, pumping means for pumping fluid including a pump body construction formed with a pump cavity and a valve cavity, flexible nonmetallic members disposed in adjacent relation, one of said members having an inlet flap valve integrally formed thereon disposed in the valve cavity and another of said members having an imperforate portion adjacent the inlet valve, one of said members having an imperforate portion extending across the pump cavity and dividing the pump cavity to form a pumping chamber and a fluid chamber, the portion of the member adjacent the inlet flap valve extending across the valve cavity and dividing the valve cavity to form a pressure chamber and a fluid inlet passage for the fluid chamber, an outlet passage for the fuel receiving chamber, outlet valve means for the outlet passage, said pumping chamber and said pressure chamber adapted to be in communication with a source of varying gas pressure for actuating the portion of the member extending across the pump cavity for actuating said portion to establish pumping impulses in said pumping chamber and to establish pressure pulses in said pressure chamber effective on the portion of the member adjacent the inlet flap valve to engage said latter portion with the inlet valve and force the inlet valve toward closed position during closing movements of the inlet valve.

3. In combination, pumping means for pumping fluid including a pump body construction'having pump body sections, the pump body construction formed with a pump cavity and a valve cavity, flexible nonmetallic members dividing the pump cavity to form a pumping chamber and a fluid chamber, the portion of the member adjacent the inlet flap valve extending across the valve cavity and dividing the valve cavity to form a pressure chamber and a fluid passage in communication with the fluid chamber, an outlet passage for the fuel receiving chamber, outlet valve means for the outlet passage, said pumping chamber and said pressure chamber adapted to be in communication with a source of varying gas pressure for actuating the portion of the member extending across the pump cavity for actuating said portion to establish pumping impulses in said pumping chamber and to establish pressure pulses in said pressure chamber effective on the portion of the member adjacent the inlet flap valve to engage said latter portion with the inlet valve and force the inlet valve toward closed position during closing movements of the inlet valve.

4. The combination according to claim 3 having a U-shaped recess in the pump body construction adjacent the valve means for the inlet passage to increase the area of the fluid passage in communication with the fluid chamber.

5. The combination according to claim 3 wherein the pump cavity and valve cavity are formed in one of the pump body sections, and means securing the pump body sections and nonmetallic members in assembled relation.

6. The combination according to claim 3 including a sealing gasket in engagement with one of said nonmetallic members, said sealing gasket having open areas at the pump cavity and at the inlet valve cavity and at the outlet valve means.

7. The combination according to claim 3 wherein the source of varying gas pressure is the varying gas pressure in the crankcase of a two-cycle engine.

8. The combination according to claim 3 wherein each of the pump body sections is provided with a planar surface area with the surface areas disposed in parallel relation, and the flexible nonmetallic members disposed between the parallel surface areas of the pump body sections.

9. The combination according to claim 3 wherein the pump body section formed with the fluid chamber has a fuel filter compartment, 21 fuel filter in the compart: ment, and means forming a wall of the compartment secured to the said pump body section adapted for connection with a fuel supply.

10. In combination, pumping means for pumping fluids including a pump body construction formed with a pump cavity and a valve cavity, diaphragm means dividing the pump cavity to form a pumping chamber and a fluid receiving. chamber and dividing the valve cavity to form a pressure chamber and a fluid inlet passage for the fluid receiving chamber, inlet valve means of flexible material for said inlet passage disposed contiguous .with the diaphragm means in the valve cavity, an outlet passage for the fuel receiving chamber, outlet flap valve means of flexible material for the outlet passage, said pumping chamber and said pressure chamber adapted to be in communication with a source of varying gas pressure for actuating the diaphragm means to establish pumping impulses in said fluid receiving chamber and to establish pressure pulses in said pressure chamber effective to engage the diaphragm means in the valve cavity with the inlet flap valve and force the inlet valve toward closed position during closing movements of the inlet valve.

11. In combination, pumping means for pumping liquid fuel to a charge forming apparatus including a pump body construction comprising two pump body sections providing a cavity therein, a pair of flexible members of nonmetallic material in contiguous relation disposed between the body sections, one of said members having an impervious portion dividing the cavity to form a pumping chamber and a fuel receiving chamber, said pumping chamber being arranged for communication with a source of varying fluid pressure for actuating the impervious portion to establish pumping impulses in said fuel receiving chamber, fuel inlet and outlet ports for the fuel receiving chamber, one of said members having flap valves integrally formed therewith for said inlet and outlet ports, recess means in one of the body sections for accommodating opening movements of said valves, the portion of the nonmetallic member adjacent the inlet valve being impervious and extending across recess means at the inlet valve to form a pressure chamber, and means establishing communication between the pressure chamber and the pumping chamber whereby varying pressures influence the portion of the memer adjacent the inlet valve to exert force to close the inlet valve during pressure pulsations in the pumping chamber.

References Cited UNITED STATES PATENTS 2,549,231 4/1951 Perkins. 2,843,050 7/1958 Harper 103l52 3,007,416 11/1961 Childs 10344 3,256,825 6/1966 Limpert et al. 103-44 ROBERT M. WALKER, Primary Examiner.

F. SUSKO, Assistant Examiner.