US3588058A - Power valve arrangement - Google Patents

Abstract

A CARBURETOR HAVING A FUEL BOWL OR RESERVOIR WITH A MAIN FUEL-METERING SYSTEM, INCLUDING A METERING RESTRICTION THEREFOR, IS PROVIDED WITH A SECOND PASSAGE MEANS IN PARALLEL WITH THE METERING RESTRICTION, THE SECOND PASSAGE MEANS IS NORMALLY MAINTAINED CLOSED BY A WEIGHTED VALVE MEMBER RESPONSIVE TO THE VACUUM GENERATED AT THE VENTURI OF THE CARBURETOR INDUCTION PASSAGE, WHEN A VENTURI VACUUM OF SUFFICIENT MAGNITUDE IS REALIZED THE SECOND PASSAGE MEANS IS AT LEAST PARTIALLY OPENED PERMITTING ADDITIONAL QUANTITIES OF FUEL TO FLOW TO THE MAIN DISCHARGE NOZZLE THEREBY ENRICHING THE FUEL-AIR RATIO OF THE COMBUSTIBLE MIXTURE FLOWING INTO THE ENGINE INTAKE MANIFOLD.

Description

United States Patent [72] Inventor Alvin S. Lucas 33700 Edmonton, Fnrmlngton, Mich. 48024 [21] Appl. No. 786,320 [22] Filed Dec. 23, 1968 [45] Patented June 28, 1971 [54] POWER VALVE ARRANGEMENT 3 Claims, 5 Drawing Figs.

[52] US. Cl. 261/67, 261/69 [51] InLCl. F02m 7/12 [50] Field 0! Search 261/69, 69.1, 51, 67

[56] References Cited UNITED STATES PATENTS 2,447,264 8/1948 Beardsley, Jr. 26l/69(. l )X 3,081,984 3/1963 Wise 261/69)( Primary Examiner-Tim R. Miles Attorney-Walter Potoroka, Sr.

ABSTRACT: A carburetor having a fuel bowl or reservoir with a main fuel-metering system, including a metering restriction therefor, is provided with a second passage means in parallel with the metering restriction; the second passage means is normally maintained closed by a weighted valve member responsive to thevacuum generated at the venturi of the carburetor induction passage, when a venturi vacuum of suflicient magnitude is realized the second passage means is at least partially opened permitting additional quantities of fuel to flow to the main discharge nozzle thereby enriching the fuel-air ratio of the combustible mixture flowing into the engine intake manifold.

PATENTEnJuuzslsn 3588.058

sum 1 or 2 PART T/IWOT/YE 5* 41 V/A S LUCAS INVIJN'R m.

BYLOM WA POWER VALVE ARRANGEMENT BACKGROUND OF THE INVENTION It has been accepted practice to provide, in carburetor structures, a power fuel enrichment system comprised of a power valve assembly carried by the carburetor in a manner so as to be affected by engine intake manifold vacuum. The manifold vacuum acting on a movable pressure-responsive member, which is adapted for operative engagement with the valving means of the power valve assembly, at idle or normal load conditions, as well as during engine deceleration, is strong enough to overcome a spring resistance so as to maintain the valving means closed. When higher power demands place a greater load on the engine and manifold vacuum drops below a predetermined value, the said spring overcomes the reduced vacuum thereby opening the valving means. Consequently, fuel flows through the open valve means and ultimately into the carburetor induction passage thereby enriching the otherwise normal fuel-air mixture. As engine demands are reduced manifold vacuum again increases. The increased vacuum acts on the pressure-responsive member to finally overcome the resistance of the said spring thereby closing the valving means and shutting off the added supply of fuel which is no longer required.

However, heretofore such power valve systems have not been entirely successful especially in situations where the internal combustion engine might exhibit manifold vacuum characteristics peculiar unto itself. Such characteristics might exist for any of a number of reasons such as, for example, engine intake and exhaust valve timing as well as the nominal size of the carburetor induction passage as compared to the piston displacement. Nevertheless, regardless of the causation, it has been found that some engines produce, under part throttle operation and relatively high air flows, a leaningout" of the fuel-air mixture. In such situations, the prior art power valve assemblies were usually incapable of correcting the fuel deficiency in the fuel-air ratio because the opening and closing of the power valve assembly was solely dependent upon the magnitude of the generated manifold vacuum.

Accordingly, the invention herein disclosed and claimed directs itself to the solution of such problems as set out above including others which will become apparent.

SUMMARY OF THE INVENTION According to the invention, a power valve arrangement comprises a housing portion containing a valving member which is adapted to be unseated from a cooperating seat member in response to vacuum created at the carburetor induction passage venturi.

Accordingly, a general object of this invention is to provide a power valve arrangement responsive to induction passage venturi vacuum for supplying additional quantities of fuel to the induction passage in order to enrich the fuel-air ratio of the motive fluid flowing therethrough during periods of relatively high rate of airflow through the induction passage.

Another object of this invention is to provide a power valve arrangement wherein a first power valve assembly effective for supplying first additional quantities of fuel to the engine is actuated in response to vacuum generated at the venturi of the carburetor induction passage and wherein a second power valve assembly effective for supplying second additional quantities of fuel to the engine is actuated in response to vacuum generated in the engine intake manifold.

Other objects and advantages of the invention will become apparent when reference is made to the following detailed description considered in conjunction with the accompanying drawings.

DESCRIPTION OF THE DRAWINGS In the drawings:

FIG. I is a cross-sectional view of a carburetor, mounted on an engine intake manifold, equipped with a power valve assembly constructed in accordance with the teachings of the invention;

FIG. 2 is a graph of a typical performance curve of the invention shown in FIG. 1 when the carburetor fuel-air ratio is plotted against the airflow through the carburetor;

FIG. 3 is a side elevational view, with portions thereof cut away and in cross section of a carburetor embodying a second form of the invention;

FIG. 4 is an enlarged cross-sectional view of a fragmentary portion of certain details of FIG. 3; and

FIG. 5 is a graph of a typical performance curve of the invention shown in FIG. 3 when the carburetor fuel-air ratio is plotted against the airflow through the carburetor.

DESCRIPTION OF PREFERRED EMBODIMENTS Referring now in greater detail to the drawings, FIG. 1 illustrates a carburetor 10 having a body 12 with an induction passage 14 formed therethrough communicating with the passageway 16 of the intake manifold 18, of an associated internal combustion engine, upon which the carburetor 10 is mounted. The induction passage 14 may be comprised of an air inlet 20, a main venturi 22 and a mixture outlet 24 in communication with manifold passageway 16. The flow through the induction passage 14 may be controlled by a throttle valve 26 mounted on a throttle shaft 28 for pivotal rotation therewith so as to be variably positioned as by manual operation thereof. Usually an air cleaner (not shown) is operatively connected to the air inlet.

Fuel is supplied to the induction passage 14 from a reservoir 30 which, in the example shown, is a float chamber of a fuel bowl assembly 31 having a float 32 therein which, as is well known in the art, actuatcs a fuel valve controlling a fuel inlet leading from any suitable source of supply.

A generally upwardly extending well or passageway 34 communicates at its upper end with a main nozzle conduit 36 which discharges at the throat of the venturi 22. A second venturi 38 may be provided to form a discharge member for the main nozzle 36. A fixed main metering restriction 40, secured in a wall of the fuel bowl assembly 31, serves to communicate fuel from reservoir 30 to main fuel system passageway 34. As is usual practice, a suitable idle fuel system may be provided so as to, as is well known in the art, communicate between reservoir 30 and induction passage 14. Such an idle fuel system may include discharge ports (as fragmentarily shown at 42 and 44) situated adjacent the edge of the throttle valve 26 when the throttle valve is in its nominally closed or curb idle condition.

An auxiliary or power valve assembly 46 is comprised of a housing portion 48, which maybe formed integrally within the structure generally defining the fuel bowl assembly 31, forming a chamber 50 the lower end of which may be provided with a valve seat member 52 having an annular seat 54 at its upper end and a calibrated restricted passageway 56 at its generally lower end. A spherical or ball-type valve 58 is normally held in seated engagement against cooperating seat 54 by av suitable weight member 60 also moveably contained within chamber 50. The upper end of chamber 50 is closed as by a cap 62. As shown, chamber 50, in the vicinity-of ball valve 58 and seat 54 is placed in communication with main well 34 as by an intermediate conduit portion 564.

As the vehicle is started into motion by the movement of the throttle valve 26 (in the counterclockwise direction in F IG. 1) in the opening direction to some intermediate position as at 26a, the rate of airflow increases past both the throttle valve 26 and the venturi 22. Since the cross-sectional area of the throat of the venturi 22 is fixed, such increases in the rate of airflow can be accomplished only by the air undergoing an increase in the velocity of flow.

As is well known in the art, after the throttle valve 26'has opened some predetermined amount and if the velocity of airflow past the venturi 22 has reached some predetermined rate, the fuel originally supplied through the idle fuel supply discharge ports 42 and 44 is substantially terminated and the main fuel-metering system, comprised of main restriction 40, main well or passageway 3d and main nozzle conduit 36,

becomes the principal source of fuel with such fuel being discharged through the auxiliary or booster venturi 38 into the induction passage 14.

As illustrated generally by the graph of FIG. 2, when the throttle valve 26 is moved from its nominally closed or curb idle condition to a more nearly opened condition the fuel-air ratio (F/A) begins to lean out in accordance with the curve identified as part throttle" and extending from point A to point B. As can be seen, this is accompanied by an increase in the rate of airflow passing through the induction passage. If such leaning out of the fuel-air ratio were to continue the ratio of fuelto air might become so low as to be insufficient to provide a suitable combustible mixture to the engine during periods of engine operation as where demands for highe. power place a greater load on the engine requiring, in turn, high airflows. 1

It should, of course, be remembered that during the full range of operation of the main fuel system the rate of fuel flow through the main nozzle conduit 36 is determined by the pressure differential across main metering restriction 40 and the efi'ective cross-sectional area of the calibrated passageway 41 formed therethrough. 7

However, in FIG. 1, the first embodiment of the invention. when the air flow through induction passage 14 reaches a predetermined value as represented by point B the vacuum generated by the air flowing past venturi 22 becomes sufficient to start to lift valve member 58 off its cooperating seat 54 against the resistance of weight 60. As this happens an additional quantity of fuel is caused to flow from reservoir 30 through calibrated passageway 56 into chamber 50 and through conduit 64 from where it flows into well 34 and through main nozzle conduit 36 discharging into the induction passage 14. Such fuel flowing through calibrated passageway or restriction 56 is in addition to that rate of fuel flow normally metered by main restriction 40. Further, the rate of such additional fuel flow will increase as the throttle valve 26 is further moved to a more nearly wide open position because such further opening movements of the throttle valve cause increases in the velocity of airflow past venturi 22 which, in turn, causes a greater pressure differential across the secondary metering restriction 56.

Accordingly, it can be seen, in FIG, 2, that as the throttle valve 26 is progressively opened from point B to a wide open throttle (WOT) condition of point C (with airflow through the induction passage 14 increasing) that an enriched fuel-air ratio as defined by the line from B to C is achieved. The portion of the graph represented by line c-D is achieved by maintaining the throttle at WOT and increasing the engine load so as to progressively reduce the airflow.

As can be seen from the preceding, the invention thus far disclosed and described provides a valving arrangement which is actuated in response to the rate of air flow through the carburetor induction passage for providing additional quantities of fuel in order to thereby enrich the fuel-air ratio of the mixture being supplied to the engine during periods of increased engine load. 1

Point 13, used to designate that particular point representative of the valve of airflow at which valve 58 will start to open, can, of course, be shifted to either the left or right in FIG. 2 by changing any of a number of actors. For example, placing a calibrated atmospheric bleed between chamber 50 and the ambient atmosphere would have the effect of reducing the value of the vacuum communicated to chamber 50 thereby causing point B to beeffectively moved to the right in FIG. 2 so as to require a higher airflow before valve 58 starts to open.

Point B could be effectively moved to the left by reducing the weight of valve member 58 or that of member 60. The general slope or shape of curve B-C can also be modified by changing the size of the calibrated passageway or secondary restriction 56. Further, greater tailoring of the additional fuel can be achieved by employing a contoured valve in place of ball valve 58. Such changes and modifications are, of course, specifically contemplated and accordingly within the scope of the invention.

SECOND EMBODIMENT OF THE INVENTION Another embodiment of the invention is disclosed by F105. 3 and 4 wherein FIG. 3 illustrates a carburetor comprising a body 112 with a throttle body 114 and air intake 116, secured thereto at opposite ends thereof, with an induction passage 118 formed therethrough adapted to be controlled at one end by a choke valve 120 secured for rotation with a choke shaft 122 suitably journaled in the walls 124 and 126 of air intake 116. The choke valve 120 and shaft 122 may be positioned as by an automatic choke mechanism many types of which are well known in the art.

Throttle body 114, suitably secured to an induction or intake manifold 128 of an internal combustion engine, continues to define the induction passage 118 and places the induction passage 118 in communication with the intake passage 130 of the engine intake manifold 128. A throttle shaft 132, joumaled in the walls of throttle body 114, has secured thereto, for rotation therewith, a throttle valve 134 which is illustrated in a partly open or part throttle position thereby permitting a controlled flow of combustible mixtures to flow through the induction passage 118, past throttle valve 134 and into passage 130 of intake manifold 128. Throttle shaft 132 may, of course, be connected to suitable throttle actuating mechanism, as is well known in the art, as for manual actuation thereof.

A main fuel nozzle 136 having its discharge end 138 situated generally within the throat of a main venturi 140, formed in the induction passage 118, communicates at its other end with a passage 142 which, in turn, is in communication with passageway or conduit 144 and a main well 146. Conduit 144 and main well 146 may be formed in the metering section of an associated fuel supply or fuel bowl assembly 148 suitably secured to the carburetor body 112.

The fuel bowl assembly 148, provided with a suitable fuel inlet, defines a fuel reservoir or chamber 150 for containing therein a quantity of liquid fuel the level of which may be determined as by any suitable means such as a float 151 and a float-controlled fuel inlet valve arrangement many of which are well known in the art.

A main fuel restriction 152, threadably received through a wall 154 in fuel bowl assembly 148, has a calibrated restriction or passageway 156 formed therethrough for communication between chamber 150 and main well 146. A power valve assembly 158, also threadably received through wall 154, is adapted to at times complete communication between chamber 150 and well 146 so as to thereby complete a second passage means between fuel chamber 150 and well 146 paralleling restricted passageway 156. I

A cavity 166, formed in carburetor body 112 generally, surrounds one end of power valve assembly 158 and is in communication with conduit 168. Conduit 168, provided with a suitable restriction 172 therein, communicates with a conduit 174 formed in intake manifold 128 and communicating with intake passageway 130.

FIG. 4 illustrates, in enlarged cross-sectional view, the power valve assembly 158 as being comprised of a housing 184 which cooperates with a coverlike member 186 to peripherally secure a pressure-responsive diaphragm member 188 therebetween. A sealing gasket 1% may be provided in order to prevent damage to the periphery of diaphragm 188. The area generally between diaphragm 188 and cover member 186 is vented to the pressure within chamber 166 as by an opening or aperture 191 formed in cover 186.

A stem member 192 secured at one end thereof to diaphragm 188, as by oppositely disposed plates 194 and 196 and a peened-over portion 198, carries a valve portion 200 thereon which is adapted to at times seat against a valve seat 202 formed in the end of housing or body 184. At other times, a spring 204 engaging, an abutment 205 carried by stem 192, moves stem 192 and valve member 200 away from seat 202 so as to complete communication between fuel bowl chamber 150 and the interior chamber 206 of valve housing 184. A plurality of generally axially extending flutes or guides 2118 may be formed within chamber 206 so as to generally guide the movement of stem 192 without in any material way restricting flow from the inlet, defined by opened valve 200 and seat 202, to the radially directed passageways or conduits 210 and 212 formed in power valve housing 184. Conduits 210 and 212, in turn, communicate with an annular chamber 214, formed in wall 154, which communicates with main well 146 as by an intermediate conduit 216 and a restriction 215 having a calibrated passageway 217 formed therethrough.

As illustrated in FIG. 3, an auxiliary power valve assembly 220, provided generally within the fuel bowl assembly 148, is comprised of a chamber 222 having its upper end capped as by member 224 and a valve seat 226 provided near its lower end. A ball valve 228 is urged into operative engagement with seat 226 as by means of a cooperating weight member 230 loosely contained within chamber 222. A metering restriction 232, having a calibrated passageway 234 formed therethrough, is received within the lower end of chamber 222. An intermediate conduit or passageway 236 serves to communicate between chamber 222 and main well 146.

Generally, it is well known in the art that the value of manifold vacuum generated by the engine will vary depending on such factors as engine speed, road load and throttle valve position. For example, with the engine operating at idle, a relatively high value of manifold vacuum will be generated because, at such time, the throttle valve 134 is in its nominally closed position illustrated in phantom line at 134a. During such time, as is well known in the art, the principal means for supplying fuel to the induction passage 118 and intake manifold 123 is by suitable conduitry and metering means collectively referred to as the idle fuel system. Such idle fuel systems are well known in the art and, for purposes of clarity, are not illustrated herein since the practice of the invention is not in any way limited to or by an associated idle fuel system. During such idle engine operation the manifold vacuum may be of a value in the order of 16.0 to 19.0 inches of mercury g)- As the vehicle is started into motion by the movement of the throttle valve 134 (in the clockwise direction in FIG. 3) in the opening direction, the load placed on the engine increases and because of the throttle valve 134 being moved toward a more fully opened position the value of the manifold vacuum decreases. The amount of decrease will depend on the load placed on the engine as well as the rapidity with which the throttle valve 134 is rotated from its nominally closed position toward a more fully opened position. If the engine load is sufficiently great and the opening movement of the throttle is sufficiently rapid, the manifold vacuum may, during this time, decrease to a value in the order of 1.0 to 4.0 inches Hg.

Further, when the vehicle is decelerating with the throttle valve nominally closed and the vehicle driving the engine, the valve of the generated manifold vacuum may well substantially exceed that established at idle engine operation and be in the order of2 l .0 to 22.0 inches Hg.

Accordingly, it can be seen that manifold or enginegenerated vacuum is related to engine operation and as such may be employed as not only an actuating force but also as a control parameter for related devices. Further, it can be seen that chamber 166 and one side 218 of diaphragm 188 will be exposed to manifold vacuum of a varying value, depending upon throttle position and engine load, by virtue of the communication established by serially situated conduits 168 and 174.

The main fuel system, comprising restriction 152, main well 146, conduits 144, 142 and main nozzle 136 serves to supply fuel to the induction passage 118 generally during normal offidle engine operation, as is well known in the art. Further, the manifold vacuum acting on diaphragm 188 at conditions of idle, normal load' conditions or deceleration is sufficient to overcome the force of spring 204 thereby holding valve member 200 shut against valve seat 202. However, when demands for higher power place a greater load on the engine and manifold vacuum decreases below a predetermined value,

spring 204 overcomes the pressure differential across diaphragm 188 and moves valve 200 off seat 222 thereby permitting additional fuel to flow from chamber 150 through the power valve inlet, interior chamber 206 and out through radial passages 210, 212 and through annulus 214 and passageway 216, including restriction 215, into main well 146. The rate of fuel flow from the fuel bowl chamber 150 to main well 146 being thusly increased by the opening of the power valve assembly 158 causes an enrichment ofthe flow through the main fuel discharge nozzle 136 resulting in, of course, the ultimate enrichment of the fuel-air mixture being supplied to the induction passage 118 and intake manifold passageway 130. As engine power demands are reduced, manifold vacuum increases; when the vacuum has sufficiently increased, the pressure differential created across diaphragm 188 overcomes the force of spring 204 and again closes valve 200 against valve seat 202.

For purposes of illustration, let it be assumed that a particular engine, on which the structure of FIG. 3 is situated, has an operating characteristic which causes the fuel-air ratio curve to be as illustrated in FIG. 5 and defined therein by points A, B and X. In comparing the graphs of FIGS. and 5, it can be seen that the portion between points A and B corresponds to that portion between points A and B. However, because of certain engine characteristics the fuel-air ratio at higher airflows than that of point B tends to become overly lean for engine requirements. Such characteristics have not been successfully overcome by the employment of only a manifold vacuum-responsive power valve assembly.

Accordingly, the auxiliary power valve assembly 220 serves to overcome such engine-operating characteristics by providin g an additional rate of fuel flow, in parallel to that rate determined by main metering restriction 152, so as to enrich the fuel-air ratio to the degree that the actual fuel-air ratio is in accordance with that portion of the curve between points B and X. The opening and closing of valve 228 is, of course, in accordance with the mode of operation of the power valve assembly 46 of FIG. 1.

In the arrangement of FIG. 3, when power valve assembly 158 would become opened, so as to supply additional enrichening fuel, the power valve assembly 220 would continue to supply its contribution of enrichening fuel assuming, of course, that sufficient airflows and venturi vacuum at venturi 140 existed. This period wherein such additional fuel is supplied by power valve assembly 158 is illustrated generally by that portion of the curve between points X and C of FIG, 5.

Although only two selected embodiments of the invention have been disclosed and described, it is apparent that other embodiments and modifications of the invention are possible within the scope of the appended claims.

Iclaim:

1. A carburetor for an internal combustion engine, comprising an induction passage, a venturi formed in said induction passage, a fuel reservoir, a main fuel-metering system including first main metering restriction means, said main fuel-metering system communicating between said reservoir and said induction passage in the vicinity of said venturi, and a power valve arrangement for at times supplying an additional rate of fuel flow to said main metering system in order to thereby enrichen the fuel-air ratio of the combustible mixture being supplied to said engine, said power valve arrangement comprising an inlet communicating with said reservoir, an outlet communicating with said main metering system and pressure-responsive valve means situated between said inlet and said outlet for at times completing communication therebetween, said pressure-responsive valve means being exposed to and responsive to vacuum created at said venturi and being effective to complete said communication between said inlet and said outlet whenever the value of said venturi vacuum is at least equal to a predetermined vacuum value, a second pressure-respom sive valving means situation in parallel to said first metering restriction means and said first-mentioned pressure-responsive valve means, said second pressure-responsive valving means including a second inlet communicating with said reservoir and a second outlet communicating with said main metering system, said second pressure-responsive valving means being exposed to and responsive to the vacuum created in the intake manifold of said engine, and said second pressureresponsive means being effective whenever the value of said manifold vacuum is less than a predetermined value of vacuum to complete communication between said second inlet and said second outlet, said first power valve arrangement and said second pressure-responsive valving means being constructed and arranged so that they operate intermittently to supplement fuel supply by said main fuel-metering system and so that said power valve arrangement responsive to venturi vacuum opens before said second pressure-responsive valving means and upon continued acceleration both said power valve arrangement and said second pressure-valving means supply additional fuel to said main fuel-metering system.

2. A carburetor for an internal combustion engine accord ing to claim 1 wherein said power valve arrangement includes second metering restriction means situated generally in said first-mentionecl inlet and serially between said reservoir and said first-mentioned pressure-responsive valve means, and third metering restriction means situated in said second outlet of said second pressure-responsive valving means.

3. A carburetor for an internal combustion engine according to claim 1 including resilient biasing means for continually urging said second pressure-responsive valving means toward an open condition so as to complete communication between said second inlet and said second outlet.

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