US3275306A

US3275306A - Fuel feed and charge forming apparatus

Info

Publication number: US3275306A
Application number: US265691A
Authority: US
Inventors: Bernard C Phillips
Original assignee: Tillotson Manufacturing Co
Current assignee: Tillotson Manufacturing Co
Priority date: 1963-03-18
Filing date: 1963-03-18
Publication date: 1966-09-27
Anticipated expiration: 1983-09-27
Also published as: GB1018521A

Description

ept- 27, W6 B. c. PHILLIPS 3,275,306

FUEL FEED AND CHARGE FORMING APPARATUS a4 6 23 INVENTOR:

5512mm EFHJLLJPE.

ATTORNEY United States Patent ration of Ohio Filed Mar. 18, 1963, Ser. No. 265,691 9 Claims. (Cl. 261-35) This invention relates to apparatus for delivering fuel mixture to an internal combustion engine and more especially to a combined fuel feeding and charge forming apparatus.

Fuel feed and charge forming apparatus have been used particularly for supplying combustible mixture for two cycle engines of the character employed to drive chain saws, lawn mowers, outboard marine engines and the like, wherein a diaphragm type carburetor and a pulse operated diaphragm type fuel pump are arranged at one side of a fuel and air mixing passage. Fuel feed and charge forming apparatus have also been used wherein the metering diaphragm of the carburetor is disposed at one side of the mixing passage and the pumping diaphragm of the fuel feeding means arranged at the opposite side of the mixing passage. In such combined carburetor and fuel feed constructions, the fuel inlet connection and components of the fuel duct system for feeding liquid fuel to the fuel chamber of the carburetor have been associated with the cover plate for the pumping diaphragm.

Such constructions have embodied a cover plate embodying bot-h fuel inlet duct and supply tube connections as Well as pulse channel connections 'for the pumplng chamber of the diaphragm pump.

An object of the invention is the provision of a combined fuel feeding and charge forming apparatus of the diaphragm type wherein the metering diaphragm of the carburetor component is disposed at one side of the mixing passage and the pumping diaphragm arranged at the opposite side of the mixing passage, the fuel feed apparatus including a cover plate formed with a pumping or pulse chamber.

Another object of the invention is the provision of a diaphragm type carburetor and a diaphragm type fuel pump wherein the components provide for a compact assembly of comparatively light weight occupying but a small space and one which may be economically manufactured for use with comparatively small internal combustion engines.

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 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 the combined diaphragm carburetor and diaphragm pump construction of the invention;

FIGURE 2 is a side elevational view of the combined carburetor and pump construction shown in FIGURE 1;

FIGURE 3 is a bottom plan view of the construction shown in FIGURE 1 with certain portions broken away;

FIGURE 4 is a view of the air inlet end of the construction shown in FIGURE 1;

FIGURE 5 is a view of the mixture outlet end of the construction shown in FIGURE 1;

FIGURE 6 is a vertical longitudinal sectional view, the view being taken substantially on the line 6-6 of FIGURE 5;

3,275,306 Patented Sept. 27, 1966 FIGURE 7 is a transverse sectional view taken substantially on the line 77 of FIGURE 3;

FIGURE 8 is a detail sectional view taken substantial- 1y on the line 88 of FIGURE 2;

FIGURE 9 is a detail sectional view taken substantiallyv on the line 9-9 of FIGURE 1;

FIGURE 10 is a fragmentary detail sectional View taken substantially on the line 1010 of FIGURE 1;

FIGURE 11 is a fragmentary detail sectional view taken substantially on the line 11-11 of FIGURE 1;

FIGURE 12 is a sectional view illustrating a modified form of the construction illustrated in FIGURE 11;

FIGURE 13 is a detail sectional view taken substantially on the line 13-13 of FIGURE 8;

FIGURE 14 is a detail sectional view illustrating a modified form of the main fuel delivery system of the carburetor, and

FIGURE 15 is a detail sectional view illustrating a modified form of venting means for the cover of the metering diaphragm of the carburetor.

The diaphragm carburetor and diaphragm pump combination of the invention is of a character particularly usable with low horsepower two cycle engines, and more especially engines of the character employed for powering chain saws, lawn mowers, portable drills and the like where a compact, light weight carburetor and pump construction is advantageous. The figures of the drawings illustrate the carburetor and pump combination approximately twice the size of the actual construction usable for most types of small two cycle engines. The carburetor and pump combination has particular utility for use with chain saws where it is particularly advantageous to reduce the weight, the carburetor of the invention being of a character which is operable in all angular positions including inverted position, a necessary requisite for satisfactory chain saw operation.

Referring to the drawings in detail, and initially to FIGURES 1 through 8, the charge forming device or carburetor component of the construction is inclusive of a body 10, which may be of cast metal or molded of resinous plastic, fashioned with an air and fuel mixing passage 12 having an air inlet region 14, a Venturi 16 fashioned with the restricted region or choke band 18, the mixing passage including a mixture outlet 20.

The mixture outlet end of the carburetor is fashioned with a uniplanar surface 22 which is adapted to be attached to a suitable boss portion of an engine crankcase or cylinder of the two cycle type or to a manifold of an engine of the four cycle type, .a suitable gasket being disposed adjacent the surface 22. The mixture outlet 20 registers with an opening in the boss portion of the crankcase where the engine is of the two cycle type for delivering air and fuel mixture into the engine crankcase through a conventional valve construction (not shown) at the admission port.

The opposite end of the body 10 is fashioned with a planar surface 24 to which may be fitted an air filter or air cleaner of conventional construction. The carburetor body 10 in the embodiment illustrated, is provided with two cylindrical passages 26, particularly shown in FIG- URES 4, 5 and 7, extending through the body 10 and accommodating bolts (not shown) for securing the air filter to the carburetor body and securing the body to the engine crankcase.

Extending across the air inlet region 14 and journaled in suitable bores formed in the body 10 is a shaft 28 supporting a disc-type valve 30 providing a choke valve. Extending across the mixture outlet 20 and journaled in suitable bores formed in the body 10 is a shaft 32 supporting a disc-type valve 34 forming a throttle valve for the carburetor. A horizontal plane passing through the at the mixing passage axis.

3 longitudinal axis of the mixing passage is illustrated at AA in FIGURE 5.

The choke shaft 28 and the throttle valve shaft 32 are disposed in angular relation to the horizontal plane AA, each shaft being on an axis at an angle of ten degrees, indicated as angle B in FIGURES 4 and 5. In the embodiment illustrated, both the choke shaft 28 and the throttle shaft 32 intersect the horizontal plane AA at the axis of the mixing passage and the axis of each of these shafts is at the same degree of angularity with respect to the horizontal plane AA.

As shown in FIGURES 5, the axes of the drilled passages 26, accommodating the mounting bolts, are disposed in a plane passing through the longitudinal axis of the mixing passage and intersecting the horizontal plane AA The plane DD extending through the axes of the bores or drilled passages 26 forms an angle of twenty degrees, indicated at E in FIGURE 5, with the horizontal plane AA.

Thus the total included angle between the plane passing through the axes of the

shafts

28 and 32 and the plane DD passing through the axes of the bores 26 wherein manipulating the choke valve 28. A portion of the throttle shaft 34 exteriorly of the body is equipped -with an arm or member 40 secured to the shaft by swaging 41, a cable or other suitable actuating means (not shown) for the throttle valve being connected to 'the member 40. A coil spring 44 is disposed between the body 10 and the arm 40 has one end anchored to the .body and the other end 45 engaging the arm 40 to bias the throttle valve toward closed or engine idling position viz. the position'shown in FIGURE 6.

An abutment screw 48 supported by a lug 49 on the body is arranged for engagement with the arm 40 for adjusting the engine idling position of the throttle valve 34. A coil spring 50 surrounds the adjusting screw 48 to frictionally hold the screw in adjusted position. The

-body 10 is formed with a generally circular shallow recess 52 providing a fuel chamber in the body, a flexible member, membrane or diaphragm 54 extending across the recess and forming one wall of the fuel chamber 52. A gasket 56 is disposed between the periphery of the diaphragm 54 and the portion of the body 10 defining the recess 52 to form a fluid tight seal.

A cover member 58, having a depressed central region providing a space 60, is disposed beneath the diaphragm 54; A plurality of screws 62 extend through suitable openings formed in the cover member 58, the diaphragm 54, the gasket 56, and are threaded into suitable bores formed in the body 10 to secure these components in assembled relation, as shown in FIGURE 7.

The cover member 58 is provided with a vent opening 64 to vent thespace 60 at the dry side of the diaphragm 54 to the atmosphere.

The diaphragm or membrane 54 is arranged to be actuated or fiexed by aspiration or reduced pressure established in the mixing passage 12 for controlling or Pressed or snugly fitted into the inlet duct 68 is an annular member or sleeve 74 having a restricted port or passage 76 therein. The inlet duct or passage 68 is in communication by way of the port 76 with a bore or passage 80 in which is slidably disposed an elongated valve body or valve member 82. The body of member 82 is of polygonally shaped cross-section providing facets to facilitate flow of liquid fuel along the valve body into the fuel chamber 52. Fashioned at the upper end of the valve body 82 is a tenon portion 84 which terminates in a cone-shaped valve portion 86, as shown in FIG. 7.

The cone-shaped valve portion 86 is adapted for cooperation with the valve seat or member 74, the coneshape portion controlling fuel -flow through the port 76. In the embodiment illustrated the cone-shaped portion 86 of the inlet valve is provided with a coating or film of nonmetallic material such as resinous plastic, bonded or otherwise adhesively joined with the cone-shaped portion. The nonmetallic material has sufficient resilient characteristics so as to readily conform to the valve seat 74 to provide a positive closing valve. If desired,

the cone-shaped valve portion 86 may be arranged toseat against an annular nonmetallic or rubber seat disposed adjacent the sleeve 74.

In the embodiment illustrated, a motion multiplying means such as a lever 96 is arranged between the diaphragm 54 and the valve body 82 for communicating relative flexure or movement of the diaphragm 54 to the valve body or member 82 to control the position of the inlet valve 86 for regulating fuel fio w into the chamber 52 in accordance with the degree of aspiration or reduced pressure established in the fuel chamber 52 from the mixing passage '12.

With particular reference to FIGURE 7, a member 90 is secured to the central region of the diaphragm, the member 90 having a tenon portion 91 extending through openings in thin reinforcing discs 92 and 93 disposed at opposite sides 'of the diaphragh 54, a portion of the tenon ibeing swaged as shown at 94 to secure the member 90 to the diaphragm.

The lever 96 is fulcrumed intermediate its ends upon a fulcrum pin or member 98 which has its end regions disposed in semicircular recesses formed in the upper wall of the recess defining the fuel chamber 52.

As shown in FIGURE 3, a screw 100 threaded into the body member is disposed so that the head portion of the screw engages a portion of the fulcrum pin 98 to secure the same in fixed relation to the body 10. The lever 96 is formed with curved portions 102 which embrace the fulcrum pin 98 as shown in FIGUR-ES 3 and 7. The long arm 104 of the level 96 is provided with a bifurcated or forked distal end region 106 which engages in a recess formed on the member '90, the recess being defined by a head portion 107 formed on member 90. Through this arrangement a positive articulate connection is established between the diaphragm and lever 96 through the member 90.

The short arm 110 of the lever 96 has its extremity bifurcated or forked to straddle a tenon 114 formed on the lower extremity of the inlet valve body 82 and terminating in a head portion 116. Through this arrangement the short arm of the lever 96 is positively but articulately connected to the inlet valve body 82. Thus through the connecting means between the member carried by the diaphragm and the lever arm 104 together withthe connection between the short lever arm and the valve body 82, the valve body 82 is responsive to the flexing movements of the diaphragm in both directions.

A spring means 118 nested in a socket 120 formed in the .body 10 and engaging the long arm of the lever 96, exerts a biasing force urging the inlet valve 86 of the valve body 82 toward closed position. Aspiration set up in the mixing passage 12 is communicated through fuel passages hereinafter described to the chamber 52,

the reduced pressure elevating the diaphragm 54 swinging the lever 96 in a counterclockwise direction as viewed in FIGURE 7 to open the inlet valve body 82 and valve portion 86 to valve in fuel into the fuel chamber 52.

The carburetor of the invention includes main or primary fuel delivery system for delivering fuel into the mixing passage for intermediate and high speed engine operation, and a secondary fuel delivery system for engine idling and low speed operation. The main or primary fuel delivery system is inclusive of a main orifice construction which includes a cylindrically shaped fitting 120 pressed into a bore formed in the body 10, the fitting being provided with an outlet i122 forming a main orifice or fuel delivery means.

The fitting 122 is provided with a counterbore 124 in which is disposed a ball check member 126 which seats against a ledge of a second counterbore 128, the ball check member 126 being retained in the counterbore 124 by means of a grid-like retainer 130 in the orifice or outlet region 122. The fitting .120 is provided with a peripheral recess 132 which is in communication with the counterbore 128 by means of transverse passages 134.

The body '10 is fashioned with a bore 136 which has a threaded portion accommodating a threaded body 138 of a high speed adjusting valve member 140, the member 140 having a needle valve portion 142 which cooperates with a restricted passage 144 in communication with the recess 1-32 in the fitting 120. The valve body 138 is provided with a knurled head 146 and a coil spring 148 is posed between the body and the knurled head 146 to set up sufiicientfriction to hold the valve member 140 in adjusted position. The bore 136 receives fuel from the chamber 52 through the supply duct or passage 150 shown in FIGURES 7 and 8.

The secondary fuel delivery system for engine idling and low speed operation is illustrated in FIGURES 6, 8 and 13. The body 10 is fashioned with a supplemental chamber 154 which is in communication with the mixing passage by way of an engine idling orifice 156 and a low speed orifice 158. The body 10 is fashioned with a bore 160 having a threaded portion to accommodate the threaded body portion 162 of a valve member 164, the latte-r having a needle valve portion 166 cooperating with a restricted passage 168 in communication with the supplemental chamber 154.

The valve .164 is formed with a knurled head 170, an expansive coil spring 172 being disposed between the head 170 and the body 10 to establish friction for holding the valve member in manually adjusted position.

The needle valve portion 166 of the valve 164 cooperates with the restriction 168 to meter or regulate fuel flow into the supplemental chamber 154 for delivery through one or both of the

secondary orifices

156 and 158.

Fuel may be delivered from the fuel chamber 52 to the supplemental chamber 154 through optional duct or passage systems. Referring to FIGURE 8, the body 10 may be fashioned with a drilled passage 176 and the outer end closed by a plug 177. A second passage 178 may be drilled into the body 10 intersecting the bore 160 and the passage 176, the outer end of the drilled passage 178 being closed by a plug 180. A short passage 182 may be optionally provided between the passage 176 and the circular recess 132 in the fitting 120.

The above described passage arrangement provides a so-called dependent idle system, that is, where the fuel supplied to the

secondary orifices

156 and 158 is metered by the high speed metering needle 142. The passage arrangement may be modified to provide an independent idle system wherein the fuel supplied to the supplemental chamber 154 is independent of the fuel supply duct system for the main orifice 122.

If a dependent idle system is desired, fuel flow from chamber 52 is as follows. Fuel flow is through the passage 150, FIGURE 8, in communication with the chamber 136 thence past the high speed metering needle valve 142 through the restriction 144 into the annular recess 132, through the short passage 182, connecting passages 176, 178 into the bore 160, past the metering needle valve 166 and through restriction 168 into the supplemental chamber 154 for delivery through the engine idling orifice 156 or the low speed orifice 158.

If an independent fuel conveying system for the secondary delivery system is desired, fuel may be secured from the chamber 52 through two different means. A passage 186, shown in FIGURE 13, may be provided in direct communication with the fuel chamber 52 and the bore 160 so that the fuel for the secondary system flows from the chamber 52 through passage186 past the adjustable needle valve 166, restriction 168 into the supplemental or auxiliary chamber 154.

An alternate path for conveying fuel to the secondary system may be as follows: The drilled passage 178 may be continued as an extension 178 connecting the bore 136 with the passage 178. Fuel flows from chamber 52 through duct 150, bore 136, passages 178', 178 into bore 160, past the metering needle 166 into the supplemental chamber 154 for delivery through the

secondary orifices

156 and 158.

The function of the check ball or valve means 126 in the main orifice construction or fitting is to prevent back bleeding of air through the main orifice into the secondary fuel channel system when one or both of the

secondary orifices

156 or 158 are delivering fuel into the mixing passage. Otherwise, air bled into the secondary fuel system would lean the fuel mixture causing the engine to stall.

The arrangement of the invention is inclusive of a pulse-operated fuel pump construction for supplying fuel under pressure to the inlet duct 68 of the carburetor.

In the embodiment illustrated, the pump is of the diaphragm type wherein inlet and outlet valves are formed as integral flap portions of the diaphragm, the pump construction being disposed on the opposite side of the mixing passage from the metering diaphragm arrangement 54 which controls the fuel inlet valve member 82.

The pump is inclusive of a flexible diaphragm 200, a plate or cover member 202 arranged at the upper side of the diaphragm, and a fuel compartment and fuel ducts or passages fashioned in the upper region of the carburetor body 10 as viewed in FIGURES 6 and 7. The diaphragm 200 engages an upper planar surface region of the body 10, and a gasket 204 is disposed between the platte 202 and the diaphragm 200. In the embodiment illustrated, the diaphragm is of substantially rectangular shape and is contiguous with the plate 202, the plate 202, the gasket and the diaphragm being provided with registering openings accommodating securing bolts 206 which are threaded into threaded bores formed in the body 10 to secure these components in assembled relation.

The body 10 is fashioned with a concave recess providing a fuel compartment or chamber 208. The diaphragm 200 at its region extending across the recess 208 is impervious and the plate 202 is formed with a recess providing a pulse or pumping chamber 210, the adjacent region of the diaphragm forming a flexible wall of the fuel compartment or chamber 208 and the pulse chamber 210, as shown in FIGURES 7, 9, 10 and 11.

The diaphragm 200 is formed with an integral tongue or flap valve portion 212 which controls fuel flow from a supply through an inlet port 214, shown in FIGURE 9.

The plate 202 is fashioned with a recess 216 to accommodate opening movements of the flap valve 212. The recess 216 is in communication with the fuel chamber 208 of the pump through connecting

ducts

218 and 219, shown in FIGURE 9. The body 10 is fashioned with an opening accommodating a spud or hollow nipple 222 having a portion 223 pressed or snugly fitted into an opening in the body 10. The nipple 222 accommodates or passage 232.

sure is shown in FIGURE 11.

the atmosphere through a vent opening 231. The auxiliary chamber 226 is in communication with the inlet port 214 adjacent the inlet valve 212 through a duct The chamber 226 forms a surge chamber or variable volume region to absorb or dampen inertia surging of the incoming fuel due to the rapid opening and closing movements of the inlet valve 212, the region 230 of the diaphragm forming a flexible or yieldable medium for absorbing or damping the surge pulses of the moving liquid fuel.

The arrangement establishing communication between the fuel chamber 208 and the fuel inlet duct 68 in the carburetor body 10 is illustrated in FIGURE 10. The

pumping diaphragm 200 is formed with a second tongue or flap valve portion 234 which cooperates with and controls an outlet port 236 formed in the body 10, the port 236 being in communication with the fuel chamber 208 by a duct or passage 238. The plate 202 is provided with a recess 240 to accommodate flexing movements of the valve 234 when the same moves to open position.

A bore 242 formed in the carburetor body 10 accommodates a fine mesh screen or llter 244, the fuel flowing through the filter 244 into the carburetor inlet duct or passage 68. The duct' arrangement for connecting the pulse chamber 210 with a source of varying fluid pressupplied by the varying pressures in the crankcase of a two cycle engine with which the carburetor and pump combination may be used or by varying pressures derived from the operation of a four cycle engine.

In the embodiment illustrated in FIGURE 11, a pulse I passage or channel 250 is formed in the carburetor body 10 and its entrance is at the end of the carburetor body secured to the crankcase of the engine, the entrance of the channel 250, shown in FIGURE 5, is arranged to register with an opening in the crankcase wall or with means connected with a source of varying fluid pressure. The channel 250 is in communication with a channel 252 formed in the body 10. The diaphragm 200 and the gasket 204 are pnovided with openings in registration with the channel 252, and a channel 254 formed in a boss portion 255 of the plate 202 is in communication A with the pulse chamber 210 by a connecting duct 256.

The operation of the fuel pump construction shown in FIGURES 7, 9, 10 and 11 is as follows: The varying or pulsating fluid pressures developed in the crankcase of a two cycle engine with which the carburetor and pump construction is used, is communicated to the pulse chamber 210 through the interconnecting

ducts

250, 252, 254 and 256 shown in FIGURE 11. The varying pressure causes the region of the diaphragm, forming a common wall of the fuel chamber 208 and the pulse chamber 210,

to rapidly flex or vibrate to establish pumping pulses in the chamber 210 which are effective, through the flexing of the diaphragm 200, to set up a pumping action in the fuel chamber 208.

Under the influence of a reduced pressure surge in the pulse chamber 210, the diaphragm 200 is flexed upwardly, as viewed in FIGURE 9, which causes fuel conveyed through the tube 224 and nipple 222 into chamber 226 to move through the connecting

ducts

232 and 214, past the flap valve 212 and through the connecting

ducts

218 and 219 into the fuel chamber 208. Upon a succeeding downward flexure or movement of the diaphragm 200, pressure is exerted on the fuel in the compartment 208 causingfuel therein to flow through the

ducts

238 and 236, past the outlet flap valve 234, through the recess The pulsing pressure is 8 240, bore 242 and the filter 244 into the inlet duct 68 of the carburetor.

The flow of fuel from the inlet duct into the metering or fuel chamber 52 in the carburetor is controlled by the position of the metering diaphragm 54 which is influenced by reduced pressure in the mixing passage 12 to regulate or control fuel flow past the inlet valve 86 into the fuel chamber 52 for delivery through either the primary fuel delivery system or the secondary fuel delivery system of the carburetor as hereinbefore described.

The surge chamber 226 performs an important function in that it enables a more continuous flow of fuel through the chamber 208 and at high frequency vibrations of the diaphragm 200, a substantial increase in the delivery of fuel through the pump to the carburetor is attained to satisfy the fuel requirements for high speed engine operation.

FIGURE 12 illustrates a modifiied form of pump cover or plate where it is desired to have a separate tube or tubular connection from the pulse chamber to the engine crankcase or other source of varying fluid pressure for vibrating or actuating the pumping diaphragm. As shown in FIGURE 12, the pump cover plate 260 may be fashioned of sheet metal and shaped to provide a concave recess forming a pulse chamber 262 arranged adjacent the fuel chamber 208, the diaphragm 200' forming a common flexible wall between the pulse chamber 262 and the fuel chamber 208'.

The central portion of the convex region 264 :of the plate 260 is provided with a bore which receives a tenon portion 266 of a hollow nipple or spud 268, the extremity of the tenon portion 266 being swaged as shown at 269 to form a fluid tight seal with the plate portion 264. The nipple 268 is connected by a tube (not shown) with the crankcase of a two cycle engine or other source of varying fluid pressure suitable for flexing 501' pulsing the diaphragm 200' to effect fluid flow through the fuel chamber 208' through a duct system of the character shown in FIGURES 9 and 10.

The arrangement shown in FIGURE 12 may be inexpensively manufactured as the plate 260 may be fashioned of sheet metal or molded or resinous plastic. The plate is secured to the carburetor body by means of screws 206'. The use of a pump plate 260 does not require any modification of the carburetor body 10, the pulse duct 252 in the carburetor body being rendered ineffective as it is closed by the plate 260.

FIGURE 14 shows a modified form of main fuel delivery system to provide a capillary of fluid seal or block to prevent back bleeding of air from the mixing passage into the secondary or engine idling system when the latter is delivering fuel into the mixing passage. In the construction shown in FIGURE 14, the main or primary fuel delivery orifice 280 in the body 10' is provided as the outlet of a passage 282 which is in communication with a bore or duct 284, the lower end of the duct 284 belng closed by a plug 286. The fuel flow from the fuel chamber 52' is by way of interconnecting passages 136 and 144'.

The fuel flow through the inlet valve mechanism of the character shown in FIGURE 7 is controlled by movement of the metering diaphragm 54 forming a flexible wall of the fuel chamber 52'. The fuel flow to the main orifice 280 is controlled by a valve member 288 having a long tapered needle portion 290 cooperating with the restriction or restricted passage 144. The valve body 288 is provided with a knurled head 292 for adjusting the needle valve 290, a spring 294 being interposed between the carburetor body and the knurled head 292 to establish friction for maintaining the valve in adjusted position.

The liquid fuel in the annular region formed between the needle valve 290 and the wall of the fuel passage 144 provides an effective liquid seal or capillary seal in this region when the secondary or engine idling orifice system is delivering fuel into the mixing passage to prevent back bleeding of air through the main orifice 280 into the secondary fuel delivery system. The principles of a capillary or liquid seal for the prevention of back bleeding through the main orifice is described in my Patent 2,841,372.

The strength of the liquids or capillary seal provided at the annular region surrounding the needle valve 290 is of a character which is readily broken or fractured upon increase in engine speed by the increase in the aspiration or reduced pressure in the mixing passage to reestablish fuel deh'very through the main orifice 280 for intermediate and high speed engine operation.

FIGURE 15 illustrates a modified arrangement for venting the space or dry chamber beneath the metering diaphragm 54". In this arrangement the body 10" is fashioned with a bore accommodating an entrance tube 300 which opens into the air inlet region 14 of the mixing passage and is in communication with interconnecting

ducts

302 and 304 formed in a cover member 306 disposed beneath the metering diaphragm 54" to vent the space 60" to the air inlet region 14.

This arrangement has the advantage of preventing foreign matter entering the chamber 60" as the air entering the inlet 14 passes through a conventional filter (not shown). The arrangement shown in FIGURE 15 has the further advantage that any drop in pressure in the fuel inlet region dueto a partially clogged screen or filter is communicated through the space 60" to more nearly effect a proper balance in pressures in the fuel chamber and the vented space beneath the diaphragm to compensate for air flow restriction of the air filter.

From the foregoing it will be apparent that the invention comprises a compact diaphragm type carburetor of the aspirated type in combination with a pulse operated fuel pump construction wherein the components have been oriented in a manner to occupy a small space and to reduce the Weight of the construction, rendering it particularly usable for portable engines such as chain saw engines, portable drills and the like where it is essential that the weight factor be reduced to a minimum.

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. In a fuel system for an internal combustion engine, a carburetor body having a mixing passage and an unvented fuel chamber arranged at one side of the mixing passage, a throttle valve in the mixing passage, a fuel metering diaphragm forming one wall of the fuel chamber, a fuel inlet for said chamber formed in the carburetor body, an inlet valve for said fuel inlet, means arranged to transmit movements of the metering diaphragm to the fuel inlet valve for controlling fuel flow into the fuel chamber, a main fuel delivery orifice opening into the mixing passage, a secondary fuel delivery orifice opening into the mixing passage, fuel channel means in said body for conveying fuel from said fuel chamber to said main and secondary orifices, a plate secured to the body and disposed at the opposite side of the mixing passage from the metering diaphragm, adjacent regions of the carburetor body and plate being formed with recesses, a pumping diaphragm between the plate and carburetor body and extending across the recesses forming therewith a fuel compartment and a pulse chamber, means to connect the pulse chamber with a source of varying fluid pressure for actuating the pumping diaphragm, said throttle valve being mounted on a shaft extending across the mixing passage and angularly arranged with respect to a horizontal plane through the axis of the mixing passage parallel to the metering diaphragm, a pair of bores formed in the carburetor body extending lengthwise throughout the full length thereof, the axes of said bores lying in a plane intersecting the axis of the mixing passage and at an angle of substantially twenty degrees with respect to a horizontal plane through the axis of the mixing passage.

2. In a fuel system for an internal combustion engine, a carburetor body having a mixing passage and an unvented fuel chamber arranged at one side of the mixing passage, a throttle valve in the mixing passage, a fuel metering diaphragm forming one wall of the fuel chamber, a fuel inlet for said chamber formed in the carburetor body, an inlet valve for said fuel inlet, means arranged to transmit movements of the metering diaphragm of the fuel inlet valve for controlling fuel flow into the fuel chamber, a main fuel delivery orifice opening into the mixing passage, a secondary fuel delivery orifice opening into the mixing passage, fuel channel means in said body for conveying fuel fromsaid fuel chamber to said main and secondary orifices, a plate secured to the body and disposed at the opposite side of the mixing passage from the metering diaphragm, adjacent regions of the carburetor body and plate being formed with recesses, a pumping diaphragm between the plate and carburetor body and extending across the recesses forming therewith a fuel compartment and a pulse chamber, means to connect the pulse chamber with a source of varying fluid pressure for actuating the pumping diaphragm, said throttle valve being mounted on a shaft extending across the mixing passage and arranged at an angle of substantially ten degrees with respect to a horizontal plane through the axis of the mixing passage parallel to the metering diaphragm, a pair of bores formed in the carburetor body extending lengthwise throughout the full length thereof, the axes of said bores lying in a plane intersecting the axis of the mixing passage and at an angle of substantially thirty degrees with respect to the angle of the throttle shaft.

3. In a fuel system for an internal combustion engine, a carburetor body having a mixing passage and an unvented fuel chamber arranged at one side of the mixing passage, Ia throttle valve in the mixing passage, a fuel metering diaphragm forming one wall of the fuel chamber, a fuel inlet for said chamber formed in the carburetor body, 'an inlet valve for said fuel inlet, a lever in the fuel chamber arranged to transmit movements of the metering diaphragm to the fuel inlet valve for controlling fuel flow into the fuel chamber, a main fuel delivery orifice opening into the mixing passage, a secondary fuel delivery orifice opening into the mixing passage, fuel channel means in said body for conveying fuel from said fuel chamber to said main and secondary orifices, means associated 'with the fuel duct means for the main orifice to prevent back bleeding of air through the main orifice when the secondary orifice is delivering fuel into the mixing passage, a plate secured to the body and disposed at the opposite side of the mixing passage from the metering diaphragm, adjacent regions of the carburetor body and plate being formed with recesses, a pumping diaphragm between the plate and carburetor body and extending across the recesses forming therewith a fuel compartment and a pulse chamber, means to connect the pulse chamber with a source of varying fluid pressure for actuating the pumping diaphragm, said throttle valve being mounted on a shaft extending across the mixing passage and arranged at an angle of substantially ten degrees with respect to a plane through the axis of the mixing passage parallel to the metering diaphragm, a pair of bores formed in the carburetor body extending lengthwise throughout the full length thereof, the axes of said bores lying in a plane intersecting the axis of the mixing passage and at an angle of substantially thinty degrees with respect to the angle of the throttle shaft.

4. In a fuel system for an internal combustion engine, a carburetor body having a mixing passage and an unvented fuel chamber arranged at one side of the mixing passage, a throttle valve in the mixing passage, a fuel metering diaphragm forming one wall of the fuel chamber, a fuel inlet for said chamber formed in the carburetor body, an inlet valve for said fuel inlet, a lever fulcrumed in the fuel chamber having an articulate connection with the metering diaphragm, said lever having an articulate connection with the fuel inlet valve, a main fuel delivery orifice opening into the imixing passage, a

secondary fuel delivery orifice opening into the mixing passage, fuel channel means in said body for conveying fuel from said fuel chamber to said main and secondary orifices, -a plate secured to the body and disposed at the opposite side of the mixing passage from the metering diaphragm, adjacent regions of the carburetor body and plate being formed with recesses, a pumping diaphragm between the plate and carburetor body and extending across the recesses forming therewith a fuel compartment and a pulse chamber, means to connect the pulse chamber with a source of varying fluid pressure for actuating the pumping diaphragm, said metering and pumping diaphragms being arranged in substantial parallelism,

said throttle valve being mounted on a shaft extending across the mixing passage and arranged at an angle of substantially ten degrees with respect to a plane through the mixing passage parallel to the metering and pumping diaphragms, a pair of bones formed in the carburetor body extending lengthwise throughout the full length thereof, the axes of said bores lying in a plane intersecting the axis of the mixing passage and (at an angle of substantially thirty degrees with respect to the angle of the throttleshaft.

5. In a fuel system for an internal combustion engine, a carburetor body having a mixing passage and an unvented fuel chamber arranged at one side of the mixing passage, a throttle valve and a choke valve having shafts passing through the mixing passage, a fuel metering diaphragm forming one wall of the fuel chamber, a fuel inlet for said chamber fonmed in the carburetor body, an inlet valve for said fuel inlet, a lever fulcrumed in the fuel chamber arranged to transmit movements of the metering diaphragm to the fuel inlet valve for controlling fuel flow into the fuel chamber, resilient means biasing the inlet valve toward closed position, orifice means opening into the mixing passage, fuel channel means in said body for conveying fuel from said fuel chamber to said orifice means, a plate secured to the body and disposed at the opposite side of the mixing passage from the metering diaphragm, adjacent regions of the carburetor body and plate being formed With recesses, a pumping diaphragm between the plate and carburetor body and extending across the recesses forming therewith a fuel compartment in the carburetor body and a pulse chamber in the plate, means to connect the pulse chamber with a source of varying fluid pressure for actuating the pumping diaphragm, said throttle valve and said choke valve shafts being substantially parallel to each other and arranged at an acute angle with respect to a plane through the mixing passage parallel to the metering diaphragm, and manually adjustable means for metering fuel flow from the fuel chamber to the orifice means, said metering diaphragm being actuated by aspiration in the mixing passage to regulate fuel flow past the inlet valve.

6. In a 'fuel system for an internal combustion engine,

- a carburetor body having a mixing passage and an unvented fuel chamber arranged at one side of the mixing 1 passage, a throttle valve in the mixing passage, a fuel metering diaphragm forming one wall of the fuel chamber, a fuel inlet for said chamber formed in the carburetor body, an inlet valve for said fuel inlet, a lever \fulcrumed in the fuel chamber arranged to transmit movements of the metering diaphragm to the fuel inlet valve for controlling fuel flow into the fuel chamber, means biasing the inlet valve toward closed position, a main fuel delivery orifice opening into the mixing passage, a

secondary fuel delivery orifice opening into the mixing passage, fuel channel means in said body for conveying fuel from said fuel chamber to said main and second ary orifices, means associated with the fuel duct means to prevent back bleeding of air through the main orifice when the secondary orifice is delivering fuel into the mixing passage, a plate secured to the body and disposed at the side of the mixing passage opposite the metering diaphragm, adjacent regions of the carburetor body and plate being formed with recesses, a pumping diaphragm between the plate and carburetor body and extending across the recesses forming therewith a fuel compartment and a pulse chamber, means to connect the pulse chamber with a source of varying fluid pressure for actuating the pumping diaphragm, said throttle valve being mounted on a shaft extending across the mixing passage and arranged at an angle of substantially ten degrees with respect to a plane through the mixing passage parallel to the metering and pumping diaphragm, and a pair of bores formed in the carburetor body extending lengthwise throughout the full length thereof, the axes of said bores lying in a plane intersecting the axis of the mixing passage and at an angle of substantially thirty degrees with respect to the throttle shaft.

7. In a fuel system for an internal combustion engine,

' a carburetor body having a mixing passage and an unvented fuel chamber arranged at one side of the mixing passage, a throttle valve in the mixing passage, a fuel metering diaphragm forming one wall of the fuel chamber, a fuel inlet for said chamber formed in the carburetor body, an inlet valve for said fuel inlet, a lever fulcrumed in the fuel chamber arranged to transmit movements of the metering diaphragm to the fuel inlet valve for controlling fuel flow into the fuel chamber, a main fuel delivery orifice opening into the mixing passage, a secondary fuel delivery orifice opening into the mixing passage, fuel channel means in said body for conveying fuel from said fuel chamber to said main and secondary orifices, means associated with the fuel duct means for the main orifice to prevent back bleeding of air through the main orifice when the secondary orifice is delivering fuel into the mixing passage, a plate secured to the body and disposed at the opposite side of the mixing passage from the metering diaphragm, adjacent regions of the carburetor body and plate being formed with recesses, a pumping diaphragm between the plate and carburetor body and extending across the recesses to form respectively a fuel compartment and a pulse chamber, means to connect the pulse chamber with a source of varying fluid pressure for actuating the pumping diaphragm, said metering and pumping diaphragms being arranged in substantial parallelism, said throttle valve being mounted on a shaft extending across the mixing passage and arranged at an angle of substantially ten degrees with respect to a plane through the mixing passage parallel to the metering and pumping diaphragms, a pair of bores formed in the carburetor body extending lengthwise throughout the full length thereof, the axes of said bores lying in a plane intersecting the axis of the mixing passage and at an angle of substantially thirty degrees with respect to the throttle shaft.

8. In a fuel system for an internal combustion engine, a carburetor including a body having a mixing passage and an unvented fuel chamber arranged at one side of the mixing passage, a throttle valve and a choke valve having shafts passing through the mixing passage, a fuel ,a main orifice opening into the mixing passage, a fuel duct in the body adjacent the main orifice, a secondary fuel delivery system formed in the body having at least one secondary orifice opening into the mixing passage at a region spaced from the main orifice, said primary and secondary fuel delivery systems being in communication with the fuel chamber and arranged to deliver fuel into the mixing passage by aspiration in the mixing passage, a valve member in the duct adjacent the main orifice arranged to prevent back bleeding of air through the main orifice into the secondary fuel delivery system when the latter is delivering fuel into the mixing passage, a second plate secured to the body at the opposite side thereof from the plate covering the metering diaphragm, a pumping diaphragm between the second plate and the body, said second plate and said body being formed at each side of the pumping diaphragm with cavities providing a fuel compartment in the carburetor body and a pulsing chamber in the second plate, inlet and outlet ports for said fuel compartment, inlet and outlet flap valves for said ports integrally formed on the pumping diaphragm, duct means connecting the outlet port with the fuel inlet, said throttle valve and said choke valve shafts being disposed at an acute angle with respect to the planes of said diaphragms, said axes being substantially parallel to each other, and passage means arranged to be connected with a source of varying fluid pressure for actuating the pumping diaphragm to effect delivery of fuel from a supply to the carburetor.

9. In a fuel system for an internal combustion engine, a carburetor body having a mixing passage and an unvented fuel chamber arranged at one side of said mixing passage, a throttle valve and a choke valve having shafts passing through the mixing passage, a fuel metering diaphragm forming one wall of the fuel chamber, a fuel inlet for said chamber formed in the carburetor body, and inlet valve for said fuel inlet, a lever fulcrumed in the fuel chamber arranged to transmit movements of the metering diaphragm to the fuel inlet valve for controlling fuel flow into the fuel chamber, resilient means biasing the inlet valve toward closed position, orifice means opening into the mixing passage, fuel channel means in said body for conveying fuel from said fuel chamber to said orifice means, a plate secured to the body and disposed at the opposite side of the mixing passage from the metering diaphragm, adjacent regions of the carburetor body and plate being formed with recesses, a pumping diaphragm between the plate and carburetor body and extending across the recesses forming therewith a fuel compartment in the carburetor body and a pulse chamber in the plate, means to connect the pulse chamber with a source of varying fluid pressure for actuating the pump diaphragm, said throttle valve and said choke valve shafts being substantially parallel to each other and arranged at an acute angle with respect to a plane through the mixing passage parallel to the pumping diaphragm, and manually adjustable means for metering fuel fiow from the fuel chamber to the orifice means, said metering diaphragm being actuated by aspiration in the mixing passage to regulate fuel fiow past the inlet valve.

References Cited by the Examiner UNITED STATES PATENTS 2,010,956 8/1935 Linga 26164 X 2,656,166 10/1953 Foster. 2,724,584 11/ 1955 Armstrong. 2,801,621 8/1957 Anderson et al. 2,841,372 7/1958 Phillips. 2,984,465 5/ 1961 Hazzard. 2,987,303 6/1961 Jones. 3,037,751 6/ 1962 Phillips. 3,160,684 12/1964 Carlson et al. 3,174,732 3/1965 Brown.

HARRY B. THORNTON, Primary Examiner.

RONALD R. WEAVER, Examiner.

Dedication 3,275,306.-Bemard 0. Phillips, Toledo, Ohio. FUEL FEED AND CHARGE FORMING APPARATUS. Patent dated Sept. 27, 1966. Dedication filed July 3, 1972, by the assignee, B org- W arm?" Corporation. Hereby dedicates to the People of the United States the entire remaining term of said patent.

[Ofli'oz'al Gazette September 12,1972]

Claims

5. IN A FUEL SYSTEM FOR AN INTERNAL COMBUSTION ENGINE, A CARBURETOR BODY HAVING A MIXING PASSAGE AND AN UNVENTED FUEL CHAMBER ARRANGED AT ONE SIDE OF THE MIXING PASSAGE, A THROTTLE VALVE AND A CHOKE VALVE HAVING SHAFTS PASSING THROUGH THE MIXING PASSAGE, A FUEL METERING DIAPHRAGM FORMING ONE WALL OF THE FUEL CHAMBER, A FUEL INLET FOR SAID CHAMBER FORMED IN THE CARBURETOR BODY, AND INLET VALVE FOR SAID FUEL INLET, A LEVER FULCRUMED IN THE FUEL CHAMBER ARRANGED TO TRANSMIT MOVEMENTS OF THE METERING DIAPHRAGM TO THE FUEL INLET VALVE FOR CONTROLLING FUEL FLOW INTO THE FUEL CHAMBER, RESILIENT MEANS BIASING THE INLET VALVE TOWARD CLOSED POSITION, ORIFICE MEANS OPENING INTO THE MIXING PASSAGE, FUEL CHANNEL MEANS IN SAID BODY FOR CONVEYING FUEL FROM SAID FUEL CHAMBER TO SAID ORIFICE MEANS, A PLATE SECURED TO THE BODY AND DISPOSED AT THE OPPOSITE SIDE OF THE MIXING PASSAGE FROM THE METERING DIAPHRAGM, ADJACENT REGIONS OF THE CARBURETOR BODY AND PLATE BEING FORMED WITH RECESSES, A PUMPING DIAPHRAGM BETWEEN THE PLATE AND CARBURETOR BODY AND EXTENDING ACROSS THE RECESSED FORMING THEREWITH A FUEL COMPARTMENT IN THE CARBURETOR BODY AND A PULSE CHAMBER IN THE PLATE, MEANS TO CONNECT THE PULSE CHAMBER WITH A SOURCE OF VARYING FLUID PRESSURE FOR ACTUATING THE PUMPING DIAPHRAGM, SAID THROTTLE VALVE AND SAID CHOKE VALVE SHAFT BEING SUBSTANTIALLY PARALLEL TO EACH OTHER AND ARRANGED AT AN ACUTE ANGLE WITH RESPECT TO A PLANE THROUGH THE MIXING PASSAGE PARALLEL TO THE METERING DAIPHRAGM, AND MANUALLY ADJUSTABLE MEANS FOR METERING FUEL FLOW FROM THE FUEL CHAMBER TO THE ORIFICE MEANS, SAID METERING DIAPHRAGM BEING ACTUATE BY ASPIRATION IN THE MIXING PASSAGE TO REGULATE FUEL FLOW PAST THE INLET VALVE.