US3404872A - Charge forming apparatus - Google Patents

Charge forming apparatus Download PDF

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US3404872A
US3404872A US55281766A US3404872A US 3404872 A US3404872 A US 3404872A US 55281766 A US55281766 A US 55281766A US 3404872 A US3404872 A US 3404872A
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fuel
chamber
valve
passage
carburetor
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Warren D Nutten
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TILLOTSON Ltd (TILLOSTSON") A CORP OF IRELAND
Tillotson Manufacturing Co
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Tillotson Manufacturing Co
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Assigned to TILLOTSON LIMITED ( TILLOSTSON"), A CORP OF IRELAND reassignment TILLOTSON LIMITED ( TILLOSTSON"), A CORP OF IRELAND ASSIGNMENT OF ASSIGNORS INTEREST. Assignors: BORG-WARNER CORPORATION, A CORP OF DE.
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    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02MSUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
    • F02M17/00Carburettors having pertinent characteristics not provided for in, or of interest apart from, the apparatus of preceding main groups F02M1/00 - F02M15/00
    • F02M17/02Floatless carburettors
    • F02M17/04Floatless carburettors having fuel inlet valve controlled by diaphragm
    • YGENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10STECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10S261/00Gas and liquid contact apparatus
    • Y10S261/68Diaphragm-controlled inlet valve

Description

Oct. 8, 1968 w, NUTTEN 3,404,872
CHARGE FORMING APPARATUS Filed May 25, 1966 5 Sheets-Sheet 1 w if 35 A 7' TOR/V5 y 3, 19768 I w. D. NUTTEN 3,404,872
CHARGE FORMING APPARATUS Filed May 25, 1966 3 Sheets-Sheet 2 .96 107 1 av A 9 /4'/ /if 19? /(W 1;;
INVENTOR. Vm/ep /v Q IVUTTE/V A 7'70/P/VE y Fig-l 152 United States Patent 3,404,872 CHARGE FORMING APPARATUS Warren D. Nutten, Erie, Mich., assignor to The Tillotson Manufacturing Company, Toledo, Ohio, a corporation of Ohio Filed May 25, 1966, Ser. No. 552,817 5 Claims. (Cl. 261-34) ABSTRACT OF THE DISCLOSURE An apparatus providing for normal fuel delivery from a first variable volume fuel chamber into the mixing passage of a diaphragm carburetor, the arrangement including a second variable volume chamber wherein the volume is varied by movements of a throttle valve in the mixing passage to deliver additional fuel into the mixing passage through the main fuel delivery orifice for engine accelerating purposes wherein fuel fiow into and out of the second chamber occurs through a single channel.
This invention relates to charge forming apparatus for forming a combustible fuel and air mixture for an internal combustion engine and more especially to a charge forming apparatus embodying a diaphragm-controlled fuel inlet valve means wherein the diaphragm is actuated by aspiration in the mixing passage, the charge forming apparatus embodying athrottle-controlled means for delivering an increased amount of fuel into the mixing passage to temporarily enrichen the fuel and air mixture for engine accelerating purposes when the throttle in the mixing passage is moved to full open or near full open position.
The present invention pertains to apparatus providing for normal fuel delivery into the mixing passage from a diaphragm controlled inlet valve and for positively delivering additional fuel into the mixing passage through the main fuel delivery orifice upon opening movement of the throttle valve in the mixing passage to temporarily enrichen the mixture for engine accelerating purposes.
Another object of the invention resides in an arrangement for temporarily increasing fuel flow through the main orifice into the mixing passage of a charge forming device wherein aspiration in the mixing passage is transmitted to a first variable volume fuel chamber for normally regulating [fuel flow into the chamber for delivery into the mixing passage, the arrangement including a second variable volume chamber the volume of which is varied by movements of the throttle valve in the mixing passage wherein fuel flow into and out of the second variable volume chamber occurs through a single channel and without the use of valve means other than valve means normally embodied in the charge forming device.
Another object of the invention resides in a diaphragm type carburetor wherein fuel flow for normal engine operation into the mixing passage is controlled by aspiration in the mixing passage, the carburetor embodying an accelerating pump positively actuated by opening movement of the throttle valve in the mixing passage to deliver fuel from a fuel pump chamber through the main orifice by way of a single duct or channel and wherein the fuel pump chamber is replenished with fuel from the carburetor fuel chamber flowing past a high speed adjusting needle thence into the single duct or passage for delivery into the fuel pump chamber.
Another object of the invention is the provision of a carburetor of the diaphragm type in which the diaphragm is actuated by aspiration in the mixing passage to admit fuel into the carburetor fuel cham- Patented Oct. 8, 1968 her, the carburetor embodying a main fuel delivery orifice having an anti-back bleed check valve and a high speed adjusting needle for the main orifice, the carburetor having a throttle operated pump and pump chamber adapted to receive fuel from the fuel chamber adjacent the high speed adjusting needle valve through a single passage and wherein opening movement of the throttle effects positive delivery of fuel from the pump chamber through the single passage to the main oriflice and into the carburetor mixing passage to enrichen the fuel and air mixture for engine accelerating purposes.
Another object of the invention is the provisions of an aspirated-type of diaphragm carburetor having a fuel inlet valve controlled by aspiration on the diaphragm and wherein fuel flow to the main fuel delivery orifice into the mixing passage is normally regulated by an adjustable needle valve, a check valve in the main fuel delivery orifice preventing back-bleeding of air into the carburetor fuel chamber when the secondary is delivering fuel into the mixing passage, the carburetor embodying an accelerating pump controlled by the throttle" valve in the mixing passage wherein opening movement of the throttle valve positively actuates the fuel pump plunger to deliver additional fuel through a single channel to the main orifice past the check valve for engine accelerating purposes and, wherein upon retraction of the pump plunger, the pump chamber is replenished from fuel through the single channel from the carburetor fuel chamber by fuel flow past the adjustable needle valve.
Another object of the invention is the provisions of a combined aspirated-type diaphragm carburetor, and fuel pump the carburetor having a main fuel delivery orifice for delivering fuel into the mixing passage from a fuel chamber past an adjustable needle valve, the fuel pump being responsive to opening movements of the throttle valve to deliver fuel from the pump chamber through the main orifice and wherein the adjustable needle valve provides resistance to fuel flow from the pump chamber into the carburetor fuel chamber so that an effective delivery of fuel from the pump chamber through the main orifice into the mixing passage is assured for engine accelerating purposes, and a single inlet and outlet channel utilized to convey fuel into and away from the pump chamber without the addition of valve means.
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 economies of manufacture and numerous other features as will forming apparatus or carburetor of the diaphragm type embodying an accelerating arrangement;
FIGURE 2 is a top plan view of the carburetor or charge forming apparatus and accelerating arrangement shown in FIGURE 1;
FIGURE 3 is an end view of the construction, the view being taken at the mounting flange end of the carburetor or charge forming apparatus;
FIGURE 4 is a longitudinal sectional view taken substantially on the line 4-4 of FIGURE 2;
FIGURE 5 is a transverse sectional view taken substantially on the line 5-5 of FIGURE 2;
FIGURE 6 is a transverse sectional view taken substantially on the line 6-6 of FIGURE 2;
FIGURE 7 is a fragmentary transverse sectional view taken substantially on the line 7-7 of FIGURE 2;
FIGURE 8 is an end view of the throttle-controlled fuel U pump actuating means, the view illustrating a portion of the fuel pump;
FIGURE 9 is a sectional view taken substantially on the line 99 of FIGURE 3, and
FIGURE 10 is a semi-schematic sectional view illustrating the relationship of the carburetor, accelerating pump and fuel channel system of the invention.
While the carburetor or charge forming apparatus and fuel pump arrangement of the invention is particularly adaptable for supplying fuel and air mixture to the crankcase of a two cycle engine, it is to be understood that the charge forming apparatus and accelerating pump construction may be used for supplying fuel and air mixture to the intake manifold of an engine of the four cycle type.
Referring to the drawings in detail, the charge'farming apparatus or carburetor illustrated is of the diaphragm type in which aspiration in the mixing passage actuates the diaphragm to control a fuel inlet valve, the arrangemerit embodying a fuel pump for delivering fuel from a fuel tank to the fuel chamber of the carburetor and an accelerating pump for delivering additional fuel into the mixing passage for engine acceleration purposes. The construction includes a carburetor body or member 10 preferably fashioned of die cast metal, the body having a mixing passage 12 in which liquid fuel and air are mixed to provide a combustible mixture for delivery to an internal combustion engine.
The mixing passage 12 includes an air inlet or inlet region 14, a Venturi 16 and a mixture outlet region 18. An air filter (not shown) of conventional construction may be disposed at the entrance of the air inlet 14.
The carburetor body at the outlet end 18 of the mixing passage is fashioned with a mounting flange 20 provided with openings 22 to receive bolts (not shown) for securing the carburetor to a crankcase 24 of a two cycle engine, or if the carburetor is employed to supply combustible mixture for a four cycle engine, the mounting flange is secured to an intake manifold.
Where the carburetor delivers combustible mixture to the crankcase of a two cycle engine, the passage in the crankcase wall is provided with conventional one way valve means (not shown).
Disposed in the air inlet region 14 of a mixing passage is a disk-type choke valve 26 mounted upon a shaft 28 journaled for rotation in bores formed in boss portions integrally provided on the carburetor body 10. Secured on one end of the shaft 28 exteriorly of the carburetor body is an arm 30 for manipulating or actuating the choke valve 26 in starting the engine with which the carburetor may be employed.
The mixture outlet 18 of the mixing passage 12 is provided with a disk-type throttle valve 32 mounted upon a shaft 34 journaled in bores formed in a wall region of the body 10 defining the mixing passage. A projecting portion of the throttle shaft 34 at one side of the body 10 is equipped with an arm 36 having an opening to receive a throttle operating rod 38 for manipulating or controlling the throttle valve 32. The arm or member 36 is fashioned with a portion 40 which is engaged by an adjusting screw 42 threaded into an opening in a boss portion 44 of the body 10 for adjusting or regulating the idle or near closed position of the throttle valve 32 for engine idling.
As particularly shownin FIGURES 4, 5, 6 and 10, the carburetor body is formed with a generally circular recess providing a relatively shallow fuel chamber 48 defined by a generally annular boss portion 49. A flexible diaphragm or membrane 50 formed of impervious material, resistant to deterioration by hydrocarbon fuels, extends across the shallow fuel chamber 48 and provides a flexible wall of the fuel chamber 48 whereby the fuel chamber is of variable volume due to flexing movement of the diaphragm 50.
Disposed between the periphery of the diaphragm 50 and the boss 49 is a sealing gasket 52 to provide a fluid tight seal between the periphery of the diaphragm and the carburetor body. A member 54 provides a cover for the diaphragm and is formed with a shallow central recess 56 to accommodate flexing movements of the diaphragm 50, the recess or space 56 being vented to the atmosphere through a vent passage 53, shown in FIGURES 6 and 10.
The arrangement includes a fuel pump construction which includes a pump body member 60 disposed adjacent the cover member 54 with a pumping diaphragm 62 disposed between the pump body member 60 and the member 54. The member 54, the pump body 60 and the diaphragms 50 and 62 are secured in assemble-d relation as shown in FIGURES l and 3 by means of screws 64 threaded into threaded openings in the carburetor body 10. The fuel chamber 48 in the carburetor is unvented to the atmosphere and the diaphragm 50 is therefore actuated or flexed by aspiration or reduced pressure established by the engine-induced air stream flowing through the mixing passage 12.
The diaphragm 50 is adapted to control, regulate or meter the flow of liquid fuel delivered from the fuel pump into the fuel chamber 48 in accordance with the normal rate of delivery of fuel from the fuel chamber 48 into the mixing passage through orifice means hereinafter described.
As particularly shown in FIGURES 6 and 10, the carburetor body is provided with a threaded bore accommodating a tubular fitting 66. Slidably disposed in the hollow interior of the fitting 66 is an inlet valve body 68 of polygonal cross section as, for example, square cross section so as to facilitate flow of liquid fuel through the fitting into the fuel chamber 48.
The valve body 68 is provided at its upper end with a cone-shaped valve or needle portion 69 arranged for cooperation with an inlet port 70 provided by an annular valve seat 72, the latter being secured in place by the tubular valve guide fitting or valve cage 66. The port 70 is in communication with a fuel inlet duct 74 provided in the carburetor body. The fuel inlet duct 74 receives fuel from the fuel pump in a manner hereinafter described.
Disposed in the fuel chamber 48 in recesses provided in the body portion defining the fuel chamber is a fulcrum pin 73, and pivotally mounted or fulcrumed on the pin 73 and disposed in the fuel chamber 48 is a lever 76 providing a motion transmitting medium between the diaphragm 50 and the fuel inlet valve member 68 for controlling the position of the fuel inlet valve portion 69. The long arm 77 of the lever is engaged by a headed member 78 mounted at the central region of the diaphragm 50 and extending through reinforcing disks 88' and 81 disposed at opposite sides of the diaphragm 50, the member 78 being swaged as at 82 to secure the disks and the member 78 to the diaphragm.
The short arm 84 of the lever 76 is bifurcated and is engaged in a circular recess in the lower end of the valve body 68 providing an articulate connection between the valve body 68 and the lever 76. Resilient means is provided for normally biasing the inlet valve 69 toward the valve seat 72. In the embodiment illustrated, an expansive coil spring 88, nested in a recess close to the fulcrum pin 73, engages the long arm of the lever adjacent the fulcrum pin 73 to establish a biasing force urging the inlet valve 69 toward closed position.
From FIGURES 6 and 10, it will be apparent that upward fiexure or movement of the diaphragm 50 causes counterclockwise movement of the lever 76 about the fulcrum 73, withdrawing the inlet valve 69 from the seat 72 to admit liquid fuel from the inlet 74 into the fuel chamber 48.
The fuel pump construction, associated with the charge forming apparatus, is of the pulse operated diaphragm type of the general character shown in Phillips Patent 2,796,838. In reference to the pump construction, the member 54 is provided with a recess or cavity 94 and the pump body 60 provided with a similar cavity 96 which are in registration as shown in FIGURES 4, 5 and 6, the diaphragm 62 extending across the cavities. The cavity 94 is in communication with the crankcase of the engine through a channel or passage 98, the entrance 99 of the passage being in the mounting flange 20' and registering with an opening in the wall of the engine crankcase 24.
The diaphragm 62 is actuated or vibrated by the varying fluid pressure pulsations occurring in the engine crankcase during engine operation. The cavity or recess 96 provides a fuel chamber of the fuel pump and the movement or actuation of the pumping diaphragm 62 establishes alternate suction and pressure in the chamber 96 to pump fuel froma supply tank to the carburetor fuel inlet passage 74 through a connecting passage 75, shown in FIGURES 6 and The pump body 60 is fashioned with a tubular nipple 100 adapted to be connected by a flexible tube (not shown) with a fuel supply tank of conventional construction.
The pump body 60 is equipped with a fine mesh screen or filter 102, shown in FIGURES 4, 6 and 10 for filtering the fuel prior to its delivery to the carburetor. The pump body 60 is provided with a circular recess to accommodate a sealing gasket 104 which is engaged by a cover or cover member 106 secured in place by a screw 107 threaded into a threaded bore in the central region of the pump body 60. The passage 108 in the nipple 100 is in communication with a passage 110, shown in FIG URES 4 and 10, for delivering fuel into the chamber 112 between the filter screen 102 and the cover 106-.
The pump body 60 is fashioned with a channel 114 in communication with an inlet port v116 of the pump, shown in FIGURE 4. Integrally formed on the pumping diaphragm 62 is an inlet flap valve 118 which controls fuel flow through the inlet port 116 and through a passage 120, shown in FIGURE 10, into the fuel chamber 96.
The fuel chamber 96 is provided with an outlet port 122 and a flap valve 124, integrally formed on the pumping diaphragm 62, controls fuel flow past the flap valve 124 into the carburetor inlet passages 74 and 75.
During a pressure pulse in the pumping chamber 9'4 the diaphragm '62 acts against the fuel in the chamber 96 to force fuel past the outlet valve 124 to the carburetor inlet passage 74. During a reduced pressure or suction impressed in chamber 94 the pumping diaphragm 62 is flexed upwardly as viewed in FIGURES 4, 5, 6 and 9 to effect fuel flow from the supply through the port .116 past the inlet flap valve 118.
Through this arrangement fuel under comparatively low pressure of about five pounds per square inch is maintained in the carburetor inlet passage 74 so that upon opening movement of the inlet valve 69 under the influence of the diaphragm 50', fuel flows into the carburetor fuel chamber 48.
The carburetor body 10 is formed with ducts, channels or passages for conveying fuel from the fuel chamber 48 into the mixing passage 12. As shown in FIGURES 7, 9 and 10, the carburetor body is provided with a bore 128 having a threaded portion accommodating a threaded portion of a valve body or valve member 130. The bore 128 receives fuel from the chamber 48 through a passage 132. A restricted passage 134 is in communication with the bore 128 and the valve body 130 has a tapered or needle valve portion 136 cooperating with the restricted passage 134 for regulating fuel flow to a main orifice.
The valve body is provided with an enlarged manipulating portion 138 and an expansive coil spring 140 is disposed between the enlarged portion 138 and an annular sealing gasket 142 surrounding the valve body 130. The sealing gasket 142 prevents seepage of fuel along the valve body. The spring 140 exerts pressure on the sealing gasket 142 and provides friction for maintaining the valve body in adjusted position.
The carburetor body is provided with a bore 144, and snugly fitted or pressed into the bore is a cylindricallyshaped fitting 146 having an axial bore 147 providing a fuel duct and a counterbore 149, the outlet 150 of the counterbore providing the main orifice for fuel delivery into the Venturi 16 of the mixing passage. The fitting 146 is fashioned with a circular recess 152 which is in communication with the restricted passage 134 as shown in FIGURES 7, 9 and 10. Communication is established between the circular recess 152 and the bore or fuel duct 147 in the fitting by a plurality of transverse passages 154.
Disposed for movement in the counterbore 149 in the fitting 146 is a valve member such as a ball check valve 156 preferably of nylon or other comparatively light weight material. Dislodgment of the ball valve 156 is prevented by a perforated grid 158 disposed adjacent the main orifice or outlet 150. The ball valve 156 is of a size to facilitate fuel flow past the valve through the counterbore 149 and through the main orifice for supplying fuel for normal and high speed engine operation.
The ball check valve 156 is adapted to seat on the ledge at the juncture of the bore 147 with the counterbore 149 and prevents back-bleeding of air through the main orifice into the secondary fuel delivery system when the latter is delivering fuel into the mixing passage for engine idling or low speed operation. The secondary fuel delivery system is illustrated in FIGURES 4, 5, 9 and 10. Formed in the carburetor body 10 is a supplemental chamber 160, the lower end of which is closed by a Welch plug 162.
The wall of the mixing passage adjacent the supplemental chamber 160 is provided with a low speed orifice 164 and a second orifice 166 for low speed engine operation. The carburetor body is fashioned with a bore 168, shown in FIGURES 5 and 10, the bore having a threaded portion accommodating the threaded portion of a second valve body 170. The bore 168 is in communication with the fuel chamber 48 by a passage 172. The bore 168 is in communication with the supplemental chamber 160 by a restricted passage 174.
The valve body 170 has a tapered or needle valve portion 176 which extends into the cooperates with the restricted passage 174 for regulating fuel flow into the supplemental chamber 160 for delivery through the secondary orifices 164 and 166. The valve body 170 has an enlarged manipulating portion 178. An annular sealing gasket 180 surrounds the valve body 170 to prevent seepage of fuel along the valve body.
An expansive coil spring 182 disposed between the enlarged portion 178 and the sealing gasket 189 provides friction for retaining the valve body 170 in adjusted position.
The operation of the secondary fuel system is as follows: When the throttle is moved to engine idling or near closed position shown in FIGURE 4, the aspiration or reduced pressure at the downstream side of the throttle valve 32 effects delivery of fuel through the idling orifice 164, the fuel flowing from chamber 48 through the passage 172, bore 168, restricted passage 174 and chamber 160. During engine idling, the ball check valve 156, shown in FIGURE 7, closes the end of tfhe bore 147 to prevent backbleeding of air into the secondary system.
The charge forming apparatus or carburetor is provided with a throttle-controlled accelerating means or pump for delivering additional fuel for engine accelerating purposes when the throttle is moved to open position. In the embodiment illustrated the member 54 is integrally formed with an enlargement or cylindrical boss portion 186 provided with a circular cylindrical well or chamber 188- in which is reciprocably disposed a piston construction 190.
The piston construction is inclusive of a body 192 preferably of metal which forms a support for a nonmetallic piston 194 of cup-shaped configuration, the piston 194 being preferably fashioned of leather or other suitable yieldable material which snugly fits the interior cylindical wall of the chamber 188.
The piston body 192 is fashioned with a circular recess 196 in which is positioned a coil spring 198, the convolutions of the spring engaging the inner wall surface of the cup-shaped piston 194 for urging or biasing the circular wall of the piston 194 into snug sealing engagement with the cylindrical wall 189 of the chamber or well 188.
The :body 192 is provided with a tubular shank or extension 280 to accommodate one end of an expansive coil spring 202. The boss 186 is provided with an extension 204 of reduced diameter fashioned with a bore 206, accommodating the opposite end of the coil spring 202. Thus the spring 202, abutting a surface of the piston body 192 and the bottom of the bore 206 normally resiliently biases the piston construction in an upward direction as viewed in FIGURES and 10.
Slidably disposed in the upper end of the chamber and well 188 above the leather piston 194 is a cylindricallyshaped disk-like member 210 fashioned with a pin or tenon 212 which extends into a bore 214 provided in the exial region of the piston body 192. An end surface of the circular disk-like member 210 is contiguous with and engages the adjacent portion of the leather piston 194, as shown in FIGURE 5. The accelerating pump is controlled by the movement of the throttle supporting shaft 34.
As shown in FIGURES 2, 3, 5, 8 and 10, there is fixedly mounted on a projecting portion of the throttle shaft 34 a cam member 220 secured to a noncircular end portion of the throttle shaft by a screw 222 or other securing means.
The member 220 is provided with a cam lobe or cam portion 224, particularly shown in FIGURE 8, of a shape whereby movement of the throttle from an idling posi- 1 tion to an open position effects rotation of the cam member 220, engaging the cam lobe 224 with the member 210, thereby moving the piston construction 190 into the well or chamber 188 to deliver additional fuel to the main orifice 150 by a channel system to be described.
An important feature of the invnetion resides in the provision of a single channel in comunication with the accelerating well or chamber 188 and the main orifice construction whereby the chamber 188 is replenished with fuel which flows past the high speed metering needle 136 through the single channel and wherein the fuel delivered from the accelerating well 188 into the mixing passage flows through the same single channel.
The well 188 is connected by means of a single channel or single channel system schematically illustrated in FIG- URE 10 at 228 which opens into the channel 188 at 230, the opposite end of the single channel or channel system 228 being in communication with the annular recess 152 in the fitting 146 as shown in FIGURES 7 and 10. The entrance of the passage 228 at the annular recess 152 is spaced from the restricted passage 134 in which fuel flows past the high speed metering or adjusting needle valve 136 for delivering fuel through the primary or main orifice 150 opening into the mixing passage.
From the illustration in FIGURE 10 it will be seen that the single passage 228 is the sole communication between the accelerating well 188 and the main fuel delivery system of the carburetor. When the throttle is moved toward near closed or idling position, the piston body 192 and the piston 194 move upwardly under the expansive pressure of the spring 202, reducing the pressure in the well 188 whereby fuel flows from the chamber 48 through passage 132 past the needle valve 136, the annular recess 152 and through the channel 228 into the well 188 to replenish a fuel supply in the well.
As the throttle valve 32 is in near closed or idling position, the ball check valve 156 is in closed position so that air is prevented from bleeding through the main orifice 150 into the passage or channel 228. Hence, the ball valve 156, being in closed position, provides means assuring fuel flow from chamber 48 past the high speed needle valve 136 into the well 188.
The operation of the carburetor and accelerating pump is as follows: Under normal and high engine speeds, the throttle 32 is in partial or full open position. In such position of the throttle valve the reduced pressure or aspiration in the Venturi 16 is effective to hold the check ball valve 156 away from its seat the aspiration or reducd pressure being communicated through the bore 147 in the fitting 146 transverse passages 154 circular recess 152 restricted passage 134 past the needle valve 136 and through passage 132 into the fuel chamber.
The aspiration or reduced pressure in the mixing passage communicated to the fuel chamber 48 reduces the pressure in the fuel chamber actuating or elevating the diaphragm 50 effecting movement of the lever 76 to open the inlet valve 69 and admit fuel from the inlet passage 74 into the fuel chamber 48. The aspiration impressed in fuel chamber 48 effects fiow of liquid fuel through the above-mentioned channels and through the main orifice into the mixing passage to provide a fuel and air mixture supplied to the engine when the throttle valve is in open or partially open position.
When the throttle is moved toward near closed or idling position, being the position shown in FIGURES 4 and 10, the pressure rises in the Venturi 16 to near atmospheric pressure and at the same time high engine suction or aspiration is effective on the engine idling orifice 164 to deliver fuel into the mixing passage at the downstream or right-hand side of the throttle valve 32 as viewed in FIGURE 10. The fuel for engine idling flows through the passage 172, shown in FIGURES 5 and 10, past the needle valve 176 through channel 174 and supplemental chamber and through the engine idling orifice 164.
During the period that the engine is idling and fuel is being delivered through the orifice 164, the ball check valve 156 is seated at the end of the bore 147 which prevents air back-bleeding from the mixing passage into the main fuel delivery system.
When the throttle valve 32 is moved from an open position toward engine idling position, the cam member 220 is rotated by the throttle shaft 34 to cause the cam contour or lobe 224 to permit upward movement of the plunger 210, piston 194 and the piston body 192 as viewed in FIGURES 5 and 10 under the expansive pressure of the coil spring 202.
This upward movement of the piston increases the effective volume of the well or chamber 188 and reduces the pressure therein as the ball check valve 156 is closed to prevent air flow into the fuel duct 147, which reduced pressure effects flow of fuel from the fuel chamber 48 through the passage 132 past the adjustable high speed metering restriction or valve 136 through the restricted passage 134, the circular recess 152, thence through the passage 228 into the well or chamber 188 to replenish fuel supply in the well.
When the throttle 32 is rapidly opened, the lobe or cam contour 224 forces the disk-like member 210, the piston 194 and the piston body 192 downwardly, as viewed in FIGURES 5, 8 and 10, forcing fuel through the single passage 228 through the circular recess 152, transverse passages 154 and bore 147 to deliver additional fuel through the main orifice 150 into the mixing passage.
Concomitantly with the opening movement of the throttle 32, the primary fuel delivery system is brought into operation as the aspiration in the Ventury 16 is increased and the reduced pressure elevates the check ball i156 and fuel for normal or high speed operation is delivered into the mixing passage past the high speed adjusting needle in the normal manner.
Thus, upon rapid opening of the throttle valve 32, fuel is concomitantly delivered through the main orifice 150 from two zones, viz. from the fuel chamber 48 through the high speed channel system in a normal manner, and from the chamber or well 188 forced through the passage 228 to the main orifice 150 by reason of the downward movement of the piston 194 in the well 188 by rotation of the cam 220 by the throttle shaft 34. The delivery of excess fuel from the well 188 ceases when movement of the throttle valve 32 ceases at the desired degree of opening dependent upon the speed. desired for the engine.
The normal high speed fuel delivery system continues in operation until the throttle is again moved to near closed or engine idling position. When the throttle is in engine idling position, the pressure in the Venturi 16 approaches atmospheric pressure and the suction impressed in the fuel chamber through the secondary orifice system delivering engine idling fuel through the orifice 164 causes the check ball 156 to be held on its seat and fuel in the well 188 replenished through the single passage 228 from the fuel chamber 48 in the manner above described.
When the throttle is rapidly opened, the cam 220 exerts substantial pressure through the piston 194 on the fuel in the well 188 and some of the fuel flowing toward the main fuel orifice 150 through the single passage 228 flows past the high speed adjusting needle 136 temporarily impeding fuel flow to the bore 147 through the passage 132.
However, the bore 147, the circular recess 152 and the transverse passages 154 are of an area to effect delivery of the necessary amount of fuel from the accelerating well 188 for engine accelerating purposes.
When the throttle reaches the desired open position, fuel flow is continued through the main orifice 150 through the high speed channel system from chamber 48 past the needle valve 136 in the conventional manner. The arrangement of accelerating pump and well provides a positive and effective means for delivering an excess of fuel through the main orifice for engine accelerating purposes without the use of any additional valve means by effecting fuel flow through a single channel 228 in filling the accelerating well 188 with fuel and exhausting fuel from the well 188.
I claim:
1. Charge forming apparatus including, in combination, body means having a fuel and air mixing passage and a recess, a throttle valve in said mixing passage, a rotatable shaft supporting the throttle valve, a flexible diaphragm forming with the recess a first fuel chamber, a fuel duct in the body means having an outlet opening into the mixing passage providing a fuel delivery orifice, an engine idling orifice opening into the mixing passage, means for conveying fuel from the first chamber to the idling orifice, a fuel channel for conveying fuel from the first fuel chamber to the fuel duct, said first chamber being unvented whereby the diaphragm is actuated by aspiration in the mixing passage, a fuel inlet in the body means, a valve for the inlet, means actuated by the diaphragm controlling said inlet valve for regulating flow of liquid fuel from a supply into the first fuel chamber, a second fuel chamber, plunger means reciprocable in said second fuel chamber, means movable with the throttle shaft for actuating the plunger means, a fuel passage between the second fuel chamber and the fuel duct adapted to convey fuel from the fuel duct to the second chamber upon movement of the plunger means in one direction and to convey fuel from the second chamber to the fuel duct upon movement of the plunger means in the opposite direction, and check valve means in the outlet region of the fuel duct to impede air flow from the mixing passage into the fuel duct when the plunger means is moved in the direction to effect fuel flow from the first fuel chamber into the second fuel chamber.
2. The combination according to claim 1 including a fuel metering restriction in the fuel channel between the first fuel chamber and the fuel duct.
3. The combination according to claim 1 including an adjustable needle valve in the fuel channel between the first fuel chamber and the fuel duct and wherein the check valve means in the outlet region of the fuel duct is a ball valve.
4. The combination according to claim 1 wherein the means movable with the throttle shaft is a cam engageable with the plunger means, and resilient means in said second fuel chamber biasing the plunger means toward the cam.
5. Charge forming apparatus including, in combination, body means having a fuel and air mixing passage and a recess, a relatively movable throttle valve in said mixing passage, a flexible diaphragm forming with the recess a first fuel chamber, a fuel duct in the body means having an outlet opening into the mixing passage providing a fuel delivery orifice, an engine idling orifice opening into the mixing passage, means for conveying fuel from the first chamber to the idling orifice, a fuel channel for conveying fuel from the first fuel chamber to the fuel duct, said first chamber being unvented whereby the diaphragm is actuated by aspiration in the mixing passage, a fuel inlet in the body means, a valve for the inlet, means actuated by the diaphragm controlling said inlet valve for regulating flow of liquid fuel from a supply into the first fuel chamber, a second fuel chamber, a relatively movable member arranged to vary the volume of said second fuel chamber, means movable with the throttle valve for actuating the relatively movable member, a fuel passage between the second fuel chamber and the fuel duct adapted to convey fuel from the fuel duct to the second chamber upon movement of the relatively movable member in one direction and to convey fuel from the second chamber to the fuel duct upon movement of the relatively movable member in the opposite direction, and check valve means in the outlet region of the fuel duct to impede air flow from the mixing passage into the fuel duct when the relatively movable member is moved in the direction to effect fuel flow from the first fuel chamber into the second fuel chamber.
References Cited UNITED STATES PATENTS 2,103,629 12/1937 Moore 26134 XR 2,732,193 1/1956 Wentz 261-34 3,085,791 4/1963 Phillips 261-35 3,250,224 5/ 1966 Phillips et al. 3,281,128 10/1966 Phillips.
RONALD R. WEAVER, Primary Examiner.
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Cited By (12)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4046844A (en) * 1976-06-30 1977-09-06 Borg-Warner Corporation Carburetor construction
JPS59218347A (en) * 1983-05-27 1984-12-08 Shinagawa Diecast Kogyo Kk Accelerating device of diaphragm type
JPS6026151A (en) * 1983-07-22 1985-02-09 Shinagawa Diecast Kogyo Kk Accelerator for film type carburetor
JPS6027768A (en) * 1983-07-25 1985-02-12 Shinagawa Diecast Kogyo Kk Accelerator for diaphragm-type carburetor
US4648998A (en) * 1985-03-11 1987-03-10 Shingawa Daikasuto Kogyo Kabushiki Kaisha Charge forming apparatus
US4931226A (en) * 1989-03-01 1990-06-05 Shinagawa Diecasting Co., Ltd. Charge forming apparatus
US6086054A (en) * 1997-05-27 2000-07-11 U.S.A. Zama, Inc. Diaphragm type carburetor
US6382598B1 (en) * 1999-11-04 2002-05-07 Walbro Japan, Inc. Fuel flow control device for diaphragm-type carburetor
US6595500B2 (en) * 2001-04-25 2003-07-22 Andreas Stihl Ag & Co. Membrane carburetor
US20040104492A1 (en) * 2002-10-09 2004-06-03 Zama Japan Carburetor fuel-adjusting device
US7172178B1 (en) * 2004-11-24 2007-02-06 Walbro Engine Management, L.L.C. Carburetor with acceleration fuel pump
US20070063357A1 (en) * 2005-09-20 2007-03-22 Yoshiharu Iwasa Accelerator apparatus for diaphragm carburetor

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2103629A (en) * 1933-02-10 1937-12-28 Maxmoor Corp Anterior throttle carburetor
US2732193A (en) * 1956-01-24 Carburetor
US3085791A (en) * 1960-08-23 1963-04-16 Tillotson Mfg Co Charge forming apparatus
US3250224A (en) * 1962-08-20 1966-05-10 Tillotson Mfg Co Pumping means for a charge forming apparatus
US3281128A (en) * 1963-08-02 1966-10-25 Tillotson Mfg Co Charge forming apparatus

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2732193A (en) * 1956-01-24 Carburetor
US2103629A (en) * 1933-02-10 1937-12-28 Maxmoor Corp Anterior throttle carburetor
US3085791A (en) * 1960-08-23 1963-04-16 Tillotson Mfg Co Charge forming apparatus
US3250224A (en) * 1962-08-20 1966-05-10 Tillotson Mfg Co Pumping means for a charge forming apparatus
US3281128A (en) * 1963-08-02 1966-10-25 Tillotson Mfg Co Charge forming apparatus

Cited By (15)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4046844A (en) * 1976-06-30 1977-09-06 Borg-Warner Corporation Carburetor construction
JPH0472063B2 (en) * 1983-05-27 1992-11-17 Shinagawa Diecast Kogyo Kk
JPS59218347A (en) * 1983-05-27 1984-12-08 Shinagawa Diecast Kogyo Kk Accelerating device of diaphragm type
JPS6026151A (en) * 1983-07-22 1985-02-09 Shinagawa Diecast Kogyo Kk Accelerator for film type carburetor
JPS6027768A (en) * 1983-07-25 1985-02-12 Shinagawa Diecast Kogyo Kk Accelerator for diaphragm-type carburetor
US4648998A (en) * 1985-03-11 1987-03-10 Shingawa Daikasuto Kogyo Kabushiki Kaisha Charge forming apparatus
US4931226A (en) * 1989-03-01 1990-06-05 Shinagawa Diecasting Co., Ltd. Charge forming apparatus
US6234457B1 (en) 1997-05-27 2001-05-22 U.S.A. Zama, Inc. Method of operating a diaphragm-type carburetor
US6086054A (en) * 1997-05-27 2000-07-11 U.S.A. Zama, Inc. Diaphragm type carburetor
US6382598B1 (en) * 1999-11-04 2002-05-07 Walbro Japan, Inc. Fuel flow control device for diaphragm-type carburetor
US6595500B2 (en) * 2001-04-25 2003-07-22 Andreas Stihl Ag & Co. Membrane carburetor
US20040104492A1 (en) * 2002-10-09 2004-06-03 Zama Japan Carburetor fuel-adjusting device
US7172178B1 (en) * 2004-11-24 2007-02-06 Walbro Engine Management, L.L.C. Carburetor with acceleration fuel pump
US20070063357A1 (en) * 2005-09-20 2007-03-22 Yoshiharu Iwasa Accelerator apparatus for diaphragm carburetor
US7216856B2 (en) * 2005-09-20 2007-05-15 Zama Japan Co., Ltd. Accelerator apparatus for diaphragm carburetor

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