US3170005A - Fuel feed system for internal combustion engines - Google Patents

Description

Feb. 16, 1965 FUEL FEED SYSTEM FOR INTERNAL COMBUSTION ENGINES Filed Jan. 50, 196-3 2 Sheets-Sheet 2 TIE-3* IN V EN TOR.

BERNARD E. PHILLJPE.

gine under United States Patent 3,170,005 FUEL FEED SYSTEM FUR HQTERNAL COMBUSTION ENGINES Bernard C.Phllll[l$, Toledo, (Ohio, assignor to The Tillotson ManufacturingCompany, Toledo, Ohio, a corporation of Ohio Filed Jan. 30, 1963, Ser, No. 254,$72

8 Claims. (Cl. 261-35) This invention relates to a fuel feed system for an internal combustion engine and more particularly to a fuel feed system for use with engines for operating chain saws glue and the fuel feed arrangement are required to function in various angular positions and in inverted positions.

Chain saws have come into general use and are extenin sparsely populated areas where there is little or no fire "protection. One of the major hazards in the use of chain saws, which are adapted to operate in all positions, is that the fuel supply'tank has been vented, and when the saw unit is inverted, fuel escapes through the vent means.

Heretoforethe fuel supply tank or receptacle attached to a chain saw unit isusually provided with both inlet and 'outlet vents in the form of separate vent valves or a single valve construction employed which will vent both inwardly and outwardly. v t a In such constructions, it has'been found that when the chain saw is usedin an angular or inverted positionwhere the fuel covers the outlet vent valve, vaporpressure gen- ,erated'within the fuel tank is often sufiicient to openthe vent valve andfuel escapes or flows past the vent valve. The leakage of fuel under these conditions presents a potential fire hazard andmany forest fires have been started due to ignition of fuel escapin'g from the'fuel tank, By reason of the adaptability of a two cycle engine to operate 'in all positions, chain saws are usually: operated by "two cycle engines and, as float-controlled carburetors will not function in extreme positions'of tilt or ininverted position,

' diaphra'gm-type carburetors have come into extensive use for supplying fuel mixture to two cycle engines for chain saw use. It is alsoconventional practiceto employa fuel pump in associationwith a diaphragm carburetor forsupplying fuel under pressure to the carburetor in any position, as gravitydelivery offuel is ineffective when-the chain saw is operated in an invertedor upside-down position.

The present invention embraces a system or method of providing for delivery of fuel to an internal combustion engine'from a fuel tank which has no outward vent thereby preventing loss or escapeof fuel from the tank or system irrespective of therelative position of the fuel supply tank or the engine.

Anotherobject of the invention is the'provision of a vacuum within-the fuel'tank which would impair the de livery. of fuel to the chargeforming device or carburetor.

" Another object of the invention is the provision of a fuel to predetermined value but which is of a 'char ac ter wherein the diaphragm, controlling, the inlet valve, is operrated by aspiration or suction inthe carburetor, mixing passage satisfactorily to admitor meter fuel flow intothe carburetor in accordance withthe requirements'of the enall opera'ting conditions or positions of the.

engine.

Another'obje ct' of the invention is the provision of a or other implements or instrumentalities wherein the ensively employed in felling large trees particularly in forests V mixing passage.

3,170,0d5 Patented Feb. 16, 1%65 diaphragm-type carburetor for use witha closed or out- 'wardly unvented fuel feed system for achain saw engine of the two cycle type wherein asufiicient force multiplication factor is provided between the diaphragm and the fuel inlet vale of the carburetor whereby the diaphragm willbe influenced by aspiration in the mixing passage to deliver the requisite amount of fuelinto the mixing passage for engine operation and wherein a spring of substantial magnitude is provided for normally biasing the inlet valve toward closed position withoutimpairing the normal operation of the diaphragm in its function of metering fuel how in acordance with therequirements of the engine.

Another object of the invention is to provide a diaphragm-type carburetor for use in a closed or unvented fuel system for aninternal combustion engine wherein a mechanical valve is positioned in the main fuel discharge orifice in the carburetor of a character which will effectively prevent back bleeding of air into thesecondary or idling and low speed orifice system into the mixing passage when the secondary system is delivering fuel into the Another object of the invention is the provision of a diaphragm-type carburetor incorporating aninlet valve normally biased toward closed position by a comparatively strong spring to resist a substantial fuel. pressure that may be developed in the fuel tank by reason of vapor but which inlet valve is controlled by the diaphragm through a high 7 ratio lever construction enabling the diaphragm to be responsive to low aspiration in. the mixing passage to regulate the position of the valve for metering-fuel into the carburetor.

Further objects and advantages are within the scope" of this invention such as relate to thearrangement, operation andfunction of the related j'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 f eatures as will be apparent from a consideration of the specificationand drawing of a form feed systemfembodying a fuel-tank without an outward I vent and a diaphragm carburetor ha'ving'an inlet "valve arrangement adapted to resist incoming fuel pressure up f chainsaw of conventional constructionfwhich is inclu- .sive of a frame Ill which, in the construction shown,

, of the invention, which-may be preferred, in which:

FIGURE 1 is a side elevational view-of a chain saw of conventional construction and a-fuel feed system of theinuention associated therewith; I

FIGURE 2 is a longitudinal sectional view through the diaphragm carburetor forming a component of the fuel feed system; 7

7 FIGURE 3 is a transverse. sectional view taken substantia-lly on the line=3-3 of FIGURE 2; 1

FIGURE 4 is a {sectional viewtaken-substantially on the line 4.4 of FIGURE 2 illustrating the fuel channel arrangementzforthe main and secondary fuel delivery orifices of the carburetor; V

:FIGURE 15 is a fragmentary sectional .view taken substanitally on. the'line 5-5, of FIGURE 4; I

FIGURE 6 is anenlarged detail sectional view illustrating a form of vacuum relief or inward vent valve for the fuel supply tank of thesystem, and

FIGURE'7 is a sectional view illustrating another form of check valve forthe main fuel delivery orifice of the carburetor. V l 1 While the fuel feed system and carburetor of the inused with I engines for powering ,o-ther "instrumentalities such gas portable tools, marine enginesof theoutboard .type or wherever the fuel feed system may be found to have utility. v

Referring to the, drawings and initially to FIGURE 1, there is illustratcd an internal combustion engine driven is integral with the crankcase 12 of a two cycle engine 14 of the air cooled type, the engine being equipped with the conventional crankshaft, piston and connecting rod (not shown). A spark plug 16 is provided for igniting the firing mixture in the cylinder of the engine. The engine exhaust pipe 18 is equipped with a sound-attenuating device or mufi ler 20 of conventional construction.

The frame is provided with a forwardly extending member 22 to which is secured an elongated plate-like member 24 providing a support and guide means for the endless or chain-type saw construction 26. The saw support 24 is secured to the frame portion 22 by means of a securing or clamping plate 28 and bolts 30. Secured to or mounted upon the frame 10 is an upwardly extending hand grip portion 34 and a rearwardly extending hand grip portion 36.

The forward end of the support member 24 is provided with a housing construction 38 within which is journaled a guide sprocket (not shown) which is engaged by the chain saw member 26. Secured to the side of the engine crankcase 12 is a housing 40 secured in place by screws 42, the housing enclosing a conventional centrifugally-actuat-ed clutch for establishing a drive connection between the engine crankshaft and a saw-driving sprocket (not shown).

In operation, when the engine is increased in speed above an idling speed by admitting increased fuel mixture from the carburetor, the increased engine speed effects actuation of the centrifugal clutch to establish a drive connection between the engine and the saw 26.

The fuel feed system of the invention is inclusive of a fuel tank 46, which may be of cylindrical or rectangular shape, supported by a bracket or mounting member 48 secured to the engine crankcase. In the embodiment illustrated, the fuel tank 46 is of cylindrical shape. The carburetor 52 is secured to the crankcase 12 and the inlet end of the, ca;rburetor provided with an air cleaner or air filter 54 of conventional construction to filter out foreign particles so that clean air is admitted to the mixing passage of the carburetor.

The throttle shaft 56 of the carburetor is provided with an arm 58 connected by a link 60 with a throttle control member or trigger 62. The throttle control member or trigger 62 is pivotally supported upon the bracket 48 by means of a pivot pin 64. The construction of the carburetor will be hereinafter described in further detail. In the form of the invention illustrated, a fuel pump 66, which may be a diaphragm pump of conventional construction, is secured to the carburetor and is preferably of the type in which a pumping diaphragm is vibrated by varying fluid pressure through connection of the pumping chamber of the pump with the crankcase 12 of the two cycle engine.

The pump construction is provided with a nipple portion 68 connected by a flexible tube 70 with a metal tube 72 extending through an opening in the fuel tank 46 and welded thereto so as to provide a fluid-tight joint between the wall of the fuel tank and the tube 72. Connected with that portion of the tube 72 interiorly of the tank 46 is a flexible tube 74 which .is equipped at its end region with a felt filter 76 to screen out any foreign particles to assure the flow of clean fuel into the carburetor.

It is preferable that the tube 72 be disposed about the mid portion of one wall of the fuel tank so that upon inversion of the engine and the fuel tank, the fuel filter 76 attached to the flexible tube 74 will fall by gravity to the lowermost portion of the tank to assure that the inlet end of the flexible tube 74 at the filter is immersed in fuel irrespective of any angular or inverted position of the fuel tank 46.

The fuel tank 46 is provided with an opening in which is mounted a fitting 80, particularly shown in FIGURE 6, which is welded to the wall of the fuel tank as shown at 82. The fitting 80 is of hollow configuration and in the embodiment illustrated, forms a filler opening for filling the fuel tank 46 with liquid fuel. The interior surface of the fitting is threaded to receive the threaded portion 84 of a filler cap or closure 86. An annular sealing gasket 87 is disposed between the upper edge region of the fitting 80 and an outwardly extending flange portion 88 of the filler cap 86 to form a fluid tight seal when the cap 86 is in closed position as shown in FIG- URE 6.

In the embodiment illustrated, the closure 86 is provided with a passage 90 in communication with a counterbore 92 formed in the closure member. Disposed in the counterbore 92 is a valve member 94 which, as shown in FIGURE 6, is in the form of a sphere or ball which seats against the ledge 96 provided by the annular region joining the passage 90 with the counterbore 92. The ledge 96 forms a seat which, when engaged by the ball 90, prevents escape of any liquid fuel or vapor from the fuel tank 46.

As there is no outlet vent means for the fuel tank 46 when the closure 86 is in closed position, the fuel supply system is unvented and hence no fuel can escape from the fuel tank or any region of the fuel conveying system between the fuel tank and the carburetor. The ball valve 94 is maintained in its seated or closed po sition under the influence of a comparatively weak coil spring 100 which is held in place by a retainer or ring 102 contained in a circular recess formed in a tenon portion 104 forming an integral portion of the closure 86, a portion 105 being swaged over the ring to secure the same in position.

The purpose of the one-way valve 94, which is biased by the slight pressure of the spring 100 toward closed position, is to provide means whereby subatmospheric pressure or vacuum, that may occur within the fuel chamber 46 by reason of delivery of fuel to the carburetor during engine operation, will be relieved by atmospheric pressure opening the valve 94 to admit air through the passage 90 into the fuel tank 46 to substantially equalize the pressure in the tank.

While the carburetor forming a component of the fuel feed system of the invention is of the diaphragm type wherein the diaphragm controlling fuel flow into the carburetor is actuated solely by aspiration in the mixing passage, the carburetor is of special construct-ion in certain respects which makes possible the successful operation of the engine with the closed or unvented fuel feed system of the invention. The carburetor is illustrated in detail in FIGURES 2 through 5 and is inelusive of a body or body member formed with an air and fuel mixing passage 112 embodying a venturi 114.

The mixing passage has an air inlet region 116 through which air enters after passing through the filter 54, the latter being shown in FIGURE 1, the mixing passage having a mixture outlet 118 which is in communication with an opening in the crankcase 12 of the engine 14 shown in FIGURE 1. J ournaled in openings in the body 110 adjacent the air inlet region 116 is a shaft 120 supporting a disc-like valve 122 providing a choke valve for the air inlet, a portion of the shaft 120 exteriorly of the carburetor body being provided with a manipulating portion or arm 124 shown in FIGURE 1.

Extending across the mixture outlet region 118 is a shaft 56 journaled in bores formed in the body 110, a. disc-like valve 128 which forms a throttle valve being; supported by the shaft for controlling fiow of fuel and. air mixture into the crankcase of the engine.

As shown in FIGURE 1, the throttle shaft 56 is connected by the link 60 with the throttle actuating member or trigger 62 hereinbefore described. The venturi 114 in the mixing passage has a choke band or restricted zone 115 as shown in FIGURE 2.

The carburetor body 110 is formed with a recess providing a fuel chamber 130 of generally circular configuration, and a flexible membrane or diaphragm 132 ex:

tends across the chamber forming a flexible wall of the chamber 130 as particularly shown in FIGURES 2 and 3. An annular gasket 131 is disposed between a surface of the carburetor body 110 and the diaphragm 132. A substantially circular disc-like member 134 is disposed beneath the diaphragm 132, the member 134 being fashioned with a central circular recess 136 providing a space to accommodate movements of the flexible diaphragm 132.

The annular region of member 134, defining the circular recess 136, is engaged with the peripheral region of the diaphragm 132 and secures the diaphragm in assembled relation with the carburetor body, the member 134 also forming a component of a fuel pump construction hereinafter described. The member 134 is provided with a vent passage or opening 138 to vent the recess or chamber 136 to establish atmospheric pressure beneath or at the dry side of the diaphragm 132. The diaphragm 132 is made of highly flexible material and may be fashioned as an impervious resin film or may be of fine fabric coated with a suitable material to render the diaphragm impervious.

Disposed within a recess 142 forming a part of the fuel chamber 130 is a lever 144 of the first order of levers, the same being pivoted intermediate its ends upon a pin or shaft 146 removably secured in an opening formed in the body 110. The outer end region of the pin 146, as shown in FIGURE 4, is provided with an enlarged threaded portion 147 threaded into the entrance region of an opening accommodating the pin 146 to V facilitate assembly of the lever 144 on the fulcrum pin.

Positioned as close as practicable to the fulcrum pin 46 and disposed between the lever 144 and a surface 150 of the body 110 is an expansive coil spring 152. The lever 144 is provided with a comparatively long arm 154, the distal end of which is adapted to be engaged by a headed member 156 mounted at the central region of the diaphragm 132, reinforcing discs 157 and 158 being disposed at opposite sides of the diaphragm, the member 156 having a tenon portion 160 extending through the discs and being riveted as shown in FIGURE 3 so as to fixedly secure member 156 to the diaphragm. The lever 144 is fashioned with a short arm 162 which engages one end region of a fuel inlet valve member 164, shown in FIGURE 3.

The carburetor body 110 is formed with a threaded bore which accommodates a threaded fitting 168 which is of sleeve-like configuration having an interior bore 170 in which the inlet valve 164 is slidably disposed. The valve member 164 is of polygonal cross-section to facilitate fuel flow past the valve.

The member 168 forms a valve cage for the member 164 and is fashioned with a polygonally shaped flange portion 172 to facilitate assembly of the cage 168 in the threaded bore in the carburetor body.

The valve member 164 is provided at its opposite end with a cone or needle-shaped valve portion 174, the needle portion extending into and cooperating with a port 176 formed by an annular valve seat member 178. The port 178 is in communication with a fuel inlet channel 180 formed in the carburetor body 110. The function and operation of the diaphragm 132, the lever 144 and the inlet valve member 164 will be hereinafter described.

The fuel inlet 180 is in communication with a fuel channel 182 which is in communication with a fuel chamber 184 of a member 186 forming a component of the fuel pump 66. The members 134 and 186 are secured in assembled relation and to the carburetor body 118 by screws 187. The fuel pump illustrated herein is of the character disclosed in my US. Patent 2,796,838 granted June 25, 1957. The pump includes a pumping diaphragm 188, a recess forming a pumping chamber 190 being formed in the member 134 which is connected by a channel means 192 through the mounting flange 119 with the crankcase of the engine.

Varying fluid pressure within the crankcase of the engine due to movements of the piston cause vibration or pumping action of the pumping diaphragm 188. The fuel chamber 184 in the fuel pump is connected with a fuel receiving compartment 196 which is in communication with the fuel chamber 184 through a fuel conveying channel controlled by a flap valve (not shown).

The fuel chamber 184 is in communication with the fuel channel 182, shown in FIGURE 3, through a flap valve arrangement (not shown) formed on the diaphragm 188.

Under the influence of pumping movements or vibrations of the pumping diaphragm 188, fuel is conveyed from the compartment 196 into the fuel chamber 184 thence through the channels 182 and 180 to the fuel inlet port 178 in the valve seat member 176. The fuel compartment 196 of the pump is provided with a cover member 200 fashioned with a tubular nipple portion 68 which is connected with a fuel conveying tube 70, shown in FIGURE 1. A screen or filter 202 is disposed between the cover member 260 and the fuel compartment 196 for straining any foreign matter out of the fuel prior to its flow through the fuel pump and into the carburetor. The cover member 200 and screen 202 are held in place by a bolt 204.

The carburetor body 119 is fashioned with orifice means for delivering fuel into the mixing passage for high speed, low speed and engine idling operation and fuel channel means for conveying fuel from the chamber 130 to the orifice means. The carburetor is fashioned with a main or primary fuel delivery system which includes a main delivery orifice 288 opening into the restricted region 115 of the venturi as shown in FIGURES 2 and 5. The carburetor is fashioned with an engine idling orifice 210 and a low speed orifice 212 opening into the mixing passage adjacent the throttle valve 128, the engine idling and low speed orifice arrangement being referred to as the secondary orifice system.

The main orifice construction is inclusive of a cylindrically shaped fitting 216 pressed or snugly fitted into a bore formed in the body and fashioned with a central bore 218 which extends only partially through the member 216. The upper end of thefitting 216 is open providing the main orifice 208, the fitting being formed with a counterbore 220 which forms at its juncture with the bore 218 a ledge 222, the latter providing a valve seat for a disc-type valve 224 which is loosely contained within the counterbore 220.

Disposed within the upper end region of the counterbore 221 is an annular member 226 provided with a diametrically arranged bar or portion 228 to prevent dislodgment :of the disc 224, the bar serving to limit the upward movement of the disc but permitting fuel to flow around the disc 224. A circumferential recess 230 is formed in the member 216 and the recess is in communication with the central bore 218 through radially arranged passages 232 shown in FIGURES 4 and 5.

At high speed operation of the engine, fuel is delivered from the bore 218 past the disc 224 and through the orifice or opening 208 into the mixing passage to be mixed with air flowing through the mixing passage. With reference to FIGURE 2 it will be seen that the engine idling orifice 210 and the low speed orifice 212 are in communication with an auxiliary chamber 236, the lower end of which is closed by a Welch plug 238.

The fuel conveying channels in the carburetor body 110 are illustrated in FIGURES 4 and 5. The carburetor is fashioned with a bore 238 which is in communication with the circumferential recess 238 on the member or fitting 216 by a restricted passage 240. The bore 238 has a threaded portion 242 to receive a threaded body portion 244 of a manually adjustable needle valve member, the valve member 244 having a tenon portion 246'terminating in a needle shaped valve portion 248 extending into the restricted passage 240.

The valve member 244 is provided with a knurled head 250, a coil spring 252 being disposed between the knurled head 250 and an annular sealing gasket 256 to prevent leakage of fuel along the valve body. The spring 252 serves to set up friction to hold the manually adjustable valve 244 in adjusted position and to maintain the sealing gasket 256 into sealing engagement with the valve body 244. The bore 238 is in communication with the fuel chamber 130 by means of a fuel passage 258.

The bore 238 is in communication with a passage or channel 260, shown in FIGURE 4, which is in communication by means of a restricted passage 262 with a bore 264, the latter being connected by a restricted passage 266 with the auxiliary chamber 236. A bore 268 is in communication with the bore 264, the bore 268 having a threaded portion to accommodate a threaded portion of a second manually adjustable valve body 270.

The valve body 270 has a tenon portion 272 which terminates in a needle valve 274 cooperating with the restricted passage 266 to meter or regulate fuel flow from the bore 264 into the supplemental chamber 236 thence to the idling and low speed orifices 210 and 212.

The manually adjustable valve 270 is provided with a knurled head 275 and a coil spring 276 is disposed between a sealing ring or gasket 278 and the head 275 to set up friction for retaining the needle valve 274 in adjusted position and to urge the sealing ring 278 into contact with the valve body 270 to prevent leakage of fuel at this region.

In the operation of the carburetor, aspiration or reduced pressure in the mixing passage set up by air flow to the engine crankcase acts upon the diaphragm 132 to elevate the diaphragm which swings the lever 144 in a counterclockwise direction, as viewed in FIGURE 3, about its fulcrum 146 which permits the valve member 164 to move away from the valve seat 176 to admit fuel from the inlet duct 180 into the fuel chamber 130.

At normal or high engine speeds with the throttle valve 128 in a substantially opened position, fuel is delivered by such aspiration through the channels or bores 258 and 238 past the metering needle valve 248 through the passage 240, the annular recess 230 in the fitting 216 through the passages 232 and 218 past the check valve 224 and through the outlet or orifice 208 of the fitting 216 into the mixing passage wherein the fuel is mixed with the air moving through the passage.

When the throttle is moved to engine idling position, that is, with the throttle valve 128 in its near closed position, shown in FIGURE 2, fuel fiows from the bore 238 through passages or channels 260, 262 and 264, past the adjustable needle valve 274 through the passage 266 and into auxiliary chamber 236 and is delivered through the engine idling orifice 210 under the influence of suction in the engine crankcase. When the throttle valve 128 is partially open, additional fuel delivery into the mixing passage occurs through the low speed orifice 212.

Whenever one or both of the orifices 210 and 212 are delivering fuel into the mixing passage, the check valve 224 is drawn into seating engagement with the valve seat or ledge 222 under the influence of engine aspiration effective through the idling or low speed orifices and thereby prevent back bleeding of air from the mixing passage through the main orifice 208 into the fuel channels and prevent leaning of the fuel delivered to the orifices 210 and 212.

If this back bleeding is not prevented by valve means, such as the valve 224, air bleeding through the main nozzle would occur which would flow into the fuel channels and cause the engine to stall. The inlet channel 180 is continuously supplied with fuel under pressure from the fuel pump 66 so that fuel is always available at the inlet port 178 for delivery into the diaphragm fuel chamber 130 as metered by the relative position of the diaphragm and inlet valve member 164.

The carburetor construction forming a component of the fuel feed system of the invention differs in important structural respects from other diaphragm carburetors of this general character such as that shown in my Patent 2,841,372. In the carburetor shown herein, the ratio of the relative lengths of the lever arms of the lever 144 is greater than in the above-mentioned patent. It has been found that the ratio of the length of the short lever arm 162 to the length of the long lever arm 154 is in the ratio of approximately one to two and one-half or greater dependent upon the size of the carburetor or the size of the engine with which the carburetor is used.

Another difference is that the spring 152 is fashioned to exert a substantially greater force on the long arm 154 of the lever 144 than in other carburetors of this type in order to offset or counterbalance the maximum fuel pressure acting against the needle valve 174 tending to open the inlet needle valve. By reason of the substantial force exerted by the spring 152, it must be placed as close to the lever fulcrum 146 as possible in order that the lever have suificient force multiplication for the aspiration acting on the diaphragm 132 to elevate the diaphragm and swing the lever 144 toward a position to open the inlet valve 164 to admit fuel into the chamber 130 for delivery into the mixing passage.

The force of the spring 152 must be sufficient to hold the inlet valve 164 in closed position against a fuel pressure of at least about ten pounds per square inch or more to assure against the opening of the inlet valve by comp'aratively high vapor pressure that may develop in the fuel tank 46. If the valve were opened by fuel pressure of the supply, fuel would flow past the inlet valve 164 and through the fuel channels in the carburetor and into the mixing passage when the engine is not in operation. It is to be understood that the force of the spring 152, holding the inlet valve 164 normally in closed position, may be varied dependent upon the vapor pressure that may be encountered by reason of ambient temperature conditions and the effect of heat from the engine as the inlet valve must be normally maintained in closed position by a biasing force exceeding the vapor pressure that may be developed in the tank.

Through the closed or unvented fuel feed system of the invention there is no liability of leakage of fuel either from the fuel tank 46 or past the fuel inlet valve 164 in the carburetor. This arrangement eliminates a potential fire hazard of other fuel feed systems heretofore used with chain saw engines caused by escape or leaking of futil from the fuel tank or through the carburetor inlet va ve.

It should be noted that the engine and chain saw, when in inverted position, will be supplied with fuel as the tube 74 will be flexed to move the fuel intake and provided by the filter 76 to a position immersed in fuel. Furthermore, in inverted position the liquid fuel cannot escape through the passage because the ball valve 94 is seated against the ledge 96.

FIGURE 7 is a view of a fitting 216' for use as a main nozzle embodying a different type of valve to prevent back bleeding of air through the main orifice. In the fitting shown in FIGURE 7, a ball check valve 280 is disposed so as to close the bore 218' in the fitting which prevents back bleeding of air into the secondary fuel system which involves the orifices 210 and 212 hereinbefore described. The ball check member 280 is prevented from being dislodged from the counterbore 220' in the fitting by a retaining bar 281 forming a part of an annular member 282 which is held in position by swaging an end region 284 of the fitting 216' over the periphery of the annular member 282.

The ball check valve 280 is of a size to permit substantial movement thereof above the seat toward the open end of the bore 218' in order to facilitate fiow of liquid fuel past the ball valve for delivery from the main orifice provided by the fitting 216'. When the secondary orifices are delivering fuel into the mixing passage, the ball check 9 valve 2,80 seats,against the ledge defining the open end of the bore 218' to prevent airble'eding from the mixing passage into the secondary fuel channel'system.

As the carbufetor component of thes'ystem is of the diaphragm type having an unvented fuel chamber, it is capable of properly functior'ring in all angular positions including inverted position and, in any position the fuel feed system is closed .or unvented so that there is no liability forfuel leakage.

' In the 'event' that the chain sawis operated in allow temperature environment setting up a subatmospheric or reduced pressure in thefuel tank 46, the higher atmospheric pressure acts upon the, ball valve 94 in the closure 86 compressing the comparatively weak spring100' to admit atmospheric air into the fuel tank to tend to equalize the pressure therein.

It is apparent that, within the scope ofrthe 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:

l. A fuel feed system for an internal combustion engine, said system including a fuel supplytank adapted to contain liquid fuel and'having a filler opening, a closure for the filler opening, a carburetor formed with a mixing passage arranged to deliver fuel and air mixture to an engine, said carburetor having a fuel inlet, means arranged between the fuel tank and the fuel inlet for conveying liquid fuel to the inlet, a relatively movable valve in the fuel inlet, resilient means normally biasing the inlet valve to closed position, means in said carburetor responsive to aspiration in the mixing passage arranged to overbalance said resilient means to effect flow of liquid fuel past the valve into the mixing passage, said closure for the filler opening of the fuel tank being normally closed to seal the tank to prevent escape of fuel from the system except through the valved fuel inlet in the carburetor, a vent for the tank, a valve for the vent, resilient means biasing the vent valve to closed position, said vent valve being arranged to admit air to the fuel tank when the pressure in the tank is below atmospheric pressure.

2. A fuel feed system for an internal combustion engine, said system including a fuel supply tank adapted to contain liquid fuel and mounted adjacent the engine, a carburetor connected with the engine, a mixing passage formed in the carburetor, a fuel inlet valve in the carburetor, a diaphragm in the carburetor, resilient means normally biasing the inlet valve toward closed position, said resilient means being of suflicient force to resist opening of the inlet under fuel pressure below ten pounds per square inch,-means arranged to communicate movement of the diaphragm to the inlet valve to control fuel flow into a fuel chamber in the carburetor, said diaphragm being actuated solely by aspiration of air flow through the mixing passage to the engine, tubular means connecting the carburetor with the fuel tank for conveying liquid fuel from the tank to a region adjacent the fuel inlet valve in the carburetor, said fuel tank having an opening formed in a wall thereof, and spring-biased closure means for said opening arranged to prevent escape of liquid fuel or vapors from the fuel tank but movable to open position upon establishment of reduced pressure in the tank to admit air into the tank.

3. A fuel feed system for an internal combustion engine, said system including a fuel supply tank adapted to sage, said diaphragm being actuated solely by aspiration of air flowthrough the mixing passage, means connecting the carburetor with the fuel tank for conveying liquid fuelfrorn the tank to the fuel inlet valve in the carburetor,

said fuel tankhaving an openingformed in a wall thereof,

and resiliently-biased valve meansfor said opening arranged to prevent escapeof liquid fuel or vapors from the fuel tank but movableto open position to admit atmospheric air into 'the ta'nk when the pressure in the tank is below atmospheric'pr'essure.

4. A fuel feed system'f'or an internal combustion engine, said system including a fuel supply tank adapted to contain liquid fuel and mounted adjacent the engine, a carburetor connected with the engine, a mixing passage formed in the carburetor, a fuel inlet valve in the carburetor, resilient means normally biasing the inlet valve toward closed position, means in said carburetor responsive to aspiration in the mixing passage acting in opposition to said resilient means to effect fuel flow past the inlet valve for delivery into the mixing passage, tubular means connecting the carburetor with the fuel tank for conveying liquid fuel from the tank to the fuel inlet valve in the carburetor, said tubular means including a flexible portion within the tank,.fuel filter means'in said tank 1 attached to the flexible portion, an inwardly opening vent valve for the tank, and resilient meansnormally biasing the vent valve to closed position.

5. A fuel feed system for an internal combustion en'- gine, said system including a fuel supply tank adapted to contain liquid fuel, a carburetor arranged to be connected with an engine, a mixing passage formed in the carbu retor, an inlet valve in the carburetor, a diaphragm in the carburetor, means normally biasing the inlet valve toward closed position, means arranged to communicate movement of the diaphragm to the inlet valve to control fuel flow into a fuel chamber in the carburetor, said diaphragm being actuated solely by aspiration of air flow to the engine through the mixing passage, means connecting the carburetor with the fuel tank for conveying liquid fuel from the tank to the fuel inlet valve in the carburetor,

said fuel tank having an opening formed in a wall thereof, closure means for said opening having a passage formed therein, a one-way valve in said passage, said valve being arranged to prevent escape of liquid fuel or vapor from said tank but permitting ingress of atmospheric air through said passage when subatmospheric pressure occurs within the fuel tank;

6. A fuel feed system for an internal combustion englne, said system including a fuel supply tank adapted to contain liquid fuel and mounted adjacent the engine, a carburetor arranged to be connected with an engine, a mixing passage formed in the carburetor, an inlet valve in the carburetor, a diaphragm in the carburetor, resilient means normally biasing the inlet valve toward closed positlon, means arranged to communicate movement of the diaphragm to the inlet valve to control fuel flow into a fuel chamber in the carburetor, said diaphragm being actuated solely by aspiration of air flow to the engine through the mixing passage, means connecting the carburetor with the fuel tank for conveying liquid fuel from the tank to the fuel inlet valve in the carburetor, said fuel tank having an opening formed in a wall thereof, closure means for said opening having a passageformed therein, a vent valve in said passage, resilient means normally biasing said vent valve to closed positionto prevent escape of liquid fuel or vapor from said tank but being movable to open position permitting ingress of atmospheric air through said passage when subatmospheric pressure occurs within the fuel tank.

7. A fuel feed system for an internal combustion en gine, said system including a fuel tank, a carburetor having a mixing passage in communication with the engine, a diaphragm forming a flexible wall of a fuel chamber in the carburetor, a fuel inlet in said carburetor, a fuel inlet valve in said inlet, a lever disposed between the diaphragm and said inlet valve, spring means engaging the lever and biasing the inlet valve toward closed position, said diaphragm being responsive to aspiration in the mixing passage for controlling the inlet valve to meter fuel flow into the fuel chamber in the carburetor, a fuel pump, a fuel chamber in said pump, means connecting the fuel supply tank with said pump for conveying fuel from the tank to the pump, the pumping means of said fuel pump being arranged to deliver fuel to the inlet of the carburetor, a valve for a passage in the fuel tank, a spring normally biasing the valve to closed position, said valve being movable to admit atmospheric air into said tank when the pressure in the tank is reduced, said fuel tank valve being normally closed to prevent escape of fuel except through said fuel conveying means.

8. A fuel feed system for an internal combustion engine, said system including a fuel tank supported adjacent the engine, a carburetor secured to the engine, said carburetor having a mixing passage in communication with the engine, a diaphragm in said carburetor forming a flexible wall of a fuel chamber in the carburetor, a fuel inlet in said carburetor, a fuel inlet valve in said inlet, a lever disposed between the diaphragm and said inlet valve, spring means engaging the lever and biasing the inlet valve toward closed position, the biasing force of said spring closing said inlet valve against fuel inlet pressure of not less than five pounds per square inch, a fuel pump secured to said carburetor, a fuel chamber in said pump, means connecting the fuel supply tank with said pump for conveying fuel from the tank to the pump, the pumping means of said fuel pump being arranged to deliver fuel to the inlet of the carburetor at a pressure insufficient to normally open said inlet valve, said fuel tank having an opening formed therein, a closure for said opening having a passage formed therein, a one-way valve disposed in said passage and resiliently biased toward closed position, said valve being arranged to prevent escape of liquid fuel and vapor from said fuel tank but being movable to admit atmospheric air through the passage into the tank when the pressure in said tank is less than atmospheric pressure, said carburetor, fuel pump and fuel tank being effective in all positions to supply fuel to the engine.

References Cited in the file of this patent UNITED STATES PATENTS 1,364,770 Lindberg Jan. 4, 1921 1,923,384 Miller Aug. 22, 1933 2,841,372 Phillips July 1, 1958 2,905,327 Phillips Sept. 22, 1959

Claims (1)

1. A FUEL FEED SYSTEM FOR AN INTERNAL COMBUSTION ENGINE, SAID SYSTEM INCLUDING A FUEL SYPPLY TANK ADAPTED TO CONTAIN LIQUID FUEL AND HAVING A FILLER OPENING, A CLOSURE FOR THE FILLER OPENING, A CARBURETOR FORMED WITH A MIXING PASSAGE ARRANGED TO DELIVER FUEL AND AIR MIXTURE TO AN ENGINE, SAID CARBURETOR HAVING A FUEL INLET, MEANS ARRANGED BETWEEN THE FUEL TANK AND THE FUEL INLET FOR CONVEYING LIQUID FUEL TO THE INLET, A RELATIVELY MOVABLE VALVE IN THE FUEL INLET, RESILIENT MEANS NORMALLY BIASIANG THE INLET VALVE TO CLOSED POSITION, MEANS IN SAID CARBURETOR RESPONSIVE TO ASPIRATION IN THE MIXING PASSAGE RRANGED TO OVERBALANCE SAID RESILIENT MEANS TO EFFECT FLOW OF LIQUID FUEL PAST THE VALVE INTO THE MIXING PASSAGE, SAID CLOSURE FOR THE FILLER OPENING OF THE FUEL TANK BEING NORMALLY CLOSED TO SEAL THE TANK TO PREVENT ESCAPE OF FUEL FROM THE SYSTEM EXCEPT THROUGH THE VALVED FUEL INLET IN THE CARBURETOR, A VENT FOR THE TANK, A VALVE FOR THE VENT, RESILIENT MEANS BIASING THE VENT VALVE TO CLOSED POSITION, SAID VENT VALVE BEING ARRANGED TO ADMIT AIR TO THE FUEL TANK WHEN THE PRESSURE IN THE TANK IS BELOW ATMOSPHERIC PRESSURE.

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