US2856168A - Transfer system - Google Patents

Description

Oct- 14, 1958 M. J. KITTLER ET AL 2,856,168

TRANSFER SYSTEM Filed May 9, v1955 2 Sheets--SheewI 1 FIG2.

INVENTORS MILTON J. KITTLER S V.. u

mn.. R

Oct. 14, 1958 M. J. KITTLER ET AL l TRANSFER SYSTEM 2 Sheets-Sheet 2 Filed May 9, 1955 P s l l I l I INVENToRs MHJON J.| |TT| ER BY M n vm F. STE NER ATTORNEYS FIGJO.

United States Patent O TRANSFER SYSTEM Milton J. Kittler, Detroit, and Melvin F. Sterner, Bloomfield Hills, Mich., assignors to Holley Carburetor Cornpany, Detroit, Mich., a corporation of Michigan Application May 9,1955, Serial No. 506,972

8 Claims. (Cl. 261-41) The present invention relates to a transfer system designed to insure smooth transition between idle and nor mal driving ranges.

All present day passenger automobiles are equipped with engines of comparatively very high horsepower output. The power required to drive the car has, on the other hand, not increased substantially over what it was ten or fifteen years ago when the engines were generally of only about one-half the present horsepower. This change in the balance between horsepower available and horsepower required means that all of the engines are regularly operating at a considerably smaller fraction of their maximum capabilities. Translating this into carburetor language, it means that under average city driving conditions the carburetor operates largely in the idle range and in the transfer range between the idle range and the main nozzle range, and a considerably less portion of time in the range where the main nozzle is the principal fuel supply means.

Under such operating conditions it is increasingly important that the carburetor be so designed that the idle fuel system meter with maximum accuracy, and,' even more, that the transfer between the idle system and the main system be accomplished with the maximum degree of smoothness. This problem of transfer has been characteristic with all plain tube carburetors, which encompasses all commercial carburetors presently used on automotive vehicles. It is recognized by those skilled in the art that it is ditlicult to accomplish a smooth transition from the idle fuel system to the main fuel system. As the air flow through the carburetor gradually increases beyond the idling range, the main nozzle gradually begins to feed fuel and at this point it is characteristic of the main nozzle to start to feed in a rather intermittent and unsteady manner. Droplets of fuel will begin to tiow through the main nozzle, but the air velocity is not sufficient to keep them ,moving rapidly nor to spray them smoothly off the end of the main nozzle. The result is that these droplets collect on the main nozzle tip and then drip olf in large droplets. The engine of course, requires a homogeneous fuel-air mixture rather than an intermittent dripping of fuel from thetnozzle. `This dripping of fuel thereby causes the engine to run in a jittery and unsteady manner. It is generally necessary to enrich the mixture ratio beyond the desired point when Calibrating the carburetor in order to allow for this poor mixing of fuel and air, with a resulting loss of economy. V y

As explained previously, this is of particular importance with present day engines where so much of the low speed driving is done in the idle and transfer range. The transfer system disclosed herein was developed for the specitic purpose of correcting this problem. y

With the foregoing general remarks in mind, it is an object of the present invention to provide a transfer system for improving operation `of a carburetor in the transfer range and to facilitate smooth transition from idle range to normal range wherein thel fuel is supplied primarily from the main nozzle,

2,856,168 Patented Oct. 14, 1958 ice It is a further object of the presentinvention to provide a transfer system comprising a transfer tube connected to a source of vacuum for drawing off droplets of fuel accumulating on the fuel supply means in the carburetor during the rst stages of operation of the main fuel nozzle.

It is a further object of the present inventionrto provide a transfer system including passage means having Figure 2 is an enlargement of a portion of the struci ture shown in Figure 1.

Figure 3 is a transverse sectional view showing the ini take port of the transfer passage of another embodiment of the present invention.

Figure 4 is a transverse sectional view showing the intake port of the transfer passage of another embodiment of the present invention.

Figure 5 is a transverse sectional view showing the intake port of the transfer passage of another embodiment of the present invention.

Figure 6 is a fragmentary sectional view showing the connection of the transfer passage to suction in yet another embodiment of the present invention.

Figure 7 is a fragmentary sectional view showing the connection of the transfer passage to suction in yet another embodiment of the present invention.

Figure 8 is a fragmentary sectional view showing the l connection of the transfer passage to suction in yet another embodiment ofthe present invention.

Figure 9 is a fragmentary sectional View showing th i connection of the transfer passage to suction in yet another embodiment of the present invention.

Figure 10 is a fragmentary sectional view illustrating r the application of the invention to an updraft carburetor.

The present invention is applicable to `any type of carburetor as for example, the conventional type of four barrel downdraft carburetor having two primary barrels for low speed operation and two secondary barrels for high speed operation. This is the type of carburetor commonly used on present day V type eight cylinder engines. However, in order t-o simplify the disclosure, the invention is illustrated `and described in conjunction with a single barrel, which may be considered a primary barrel of a two stage, four barrel carburetor. On the other hand, the invention is equally useful in conjunction with a single barrel carburetor or a carburetor having any number of barrels.

Referring now to Figures l and 2 there is shown a carburetor having a barrel 10 provided with the usual dicated in Figure l the region above throttle plate 16 is substantially at atmospheric pressure or slightly below atmospheric pressure and is normally the high pressure part of the carburetor air system. The area below throttle plate 16 is always at a higher vacuum than the area above the throttle plate and may be called the low pressure side of the carburetor air passage system. In the following paragraphs the high pressure area will be under 3 stood to be that area above throttle plate 16 and the high vacuum or low pressure area will be understood to be that area below throttle plate 16. Where an updraft carburetor is discussed rather than a downdraft carburetor, the relationship ofthe high pressure and low pres sure area is obviously reversed since the flow is .in an upward direction rather than in a downward direction.

The carburetor includes an idle air bleed supply system including a passage 28, adjustable needle valve 36, and outlet port 32 located in the barrel below the throttle plate 16. As is well understood in the art, when the throttle plate is closed or substantially closed, vacuum below the throttle plate 16 operates through the passage 28 to draw suicient fuel for idling operation of the engine through tubular member 34. Passage 35 connects passage 28 to the barrel 10 above throttle plate 16, as shown in Figure 2. While not illustrated in the other figures, this second idle discharge passage is conventional, and will ordinarily be provided.

During idle operation of the engine, air pressure at the mainl nozzle 18 is substantially atmospheric and no fuel is drawn through the nozzle 18. However, as the throttle plate 16 is gradually opened, the pressure at the` main nozzle 18 decreasesy gradually and the vacuum applied thereby to the fuel in the well 22 eventually draws fuell up into the nozzle where it commences to discharge into the barrel. During the initial operation of the nozzle 18 while vacuum is increasing, the fuel is not drawn smoothly from the nozzle in a spray, nor is it atomized as is desirable. Instead, it tends to accumulate in small droplets which run together and eventually drops of fuel drop off the nozzle and are drawn into the manifold and thence into the cylinders of the internal cornbustion engine in an intermittent and improperly mixed or atomized condition.

In accordance with the present invention a transfer system including a transfer passage 40 is provided. The transfer passage 40 communicates with. a transfer tube 42 having an intake port 44 located in close proximity to the fuel supply means in thel Venturi 14 and in position to draw olf droplets of liquid fuel before they gather into large drops and accumulate on the nozzle 18. The other end of the transfer passage communicates with a source of vacuum. As illustrated in Figures l and 2, the lower end of the transfer passage 40 communicates with the Vend portion 46 of the passage 28 which terminates-in the outlet port 32 of the idle fuel supply system previously described. Accordingly,` as the throttle plate 16 movesl toward open position so as to cause fuel to commence to flow through the main nozzle'18, vacuum is applied at the intake port 44 and causes droplets of fuel to be drawn through the transfer passage and discharged into the barrel belowthe throttle. In this case, the fuel is utilized in the most efficient manner and most important, intermittent supply of relatively large drops of unatomized fuel to the engine is effectively prevented.

Referring now to Figure 3 there is illustrated a similar arrangement in which the upper end of the transfer tube 42 is located with its intake port 44 in position adjacent the lower or downstream edge of a booster Venturi indicated generally at 50. It may be mentioned at this time that the exact placement of the intake port will be de termined by the particular means for supplying the main fuel feed yto the barrel, and in a proper case where a main nozzle and booster Venturi are both provided, it may be desirable to provide ay transfer system including branched tubesor passages having intake ports adjacent both the nozzleand booster Venturi or any other element in the carburetor wherev fuel tends to collect in droplets during transition from idle to normal range.

Referring now to Figure 4, the main fuel supply means in the Venturi 14 of the barrel 10 is illustrated as a downwardly inclined tube 54, and in this ease the upper endof the transfer tube 42 is shown as having its intake 4 port 44 downstream from and closely adjacent to the port at the end of the fuel nozzle 54.

Referring now to Figure 5 there is shown a main fuel supply nozzle in the form of an upwardly inclined tube 5o and the transfer tube 42 is shown as having its intake port 44 at the downstream side of and closely adjacent to the port at the end of the fuel nozzle 56.

lt will be appreciated that the specific variations of the invention illustrated in Figures 3, 4 and 5 relate only to the upper end of the transfer passage, and particularlyto the relationship between the intake port d4 at the end of the transfer tube 42 with the particular main fuel supply means in the carburetor.

Referring now to Figure 6 there is illustrated another embodiment of the present invention in which the passage 44) of the transfer system has a restricted connection 6@ with the passage 2f of the idle fuel supply system. The restricted connection. 6i) between the passages 28 and 40 is located above the needle valve 30 which is used to adjust the ow of fuel under idlingconditions into the barrel l@ of the carburetor below the throttle plate 16 thereof.

Referring now to Figure 7 there is illustrated another embodiment of the present invention wherein the discharge end of the transfer system includes a port 70 connected by a passage 'i2 communicating with the vertically eX- tending transfer passage d0. It will be observed that the outlet or discharge port 70 is located below the throttle plate 16 and hence, at a zone of relatively low pressure or high vacuum in the transfer system during idle and transfer range. This embodiment of the invention differs specifically from, that illustrated in Figure l in that the sourcel of vacuum to which the transfer system 1s connected is in this case independent vof the idle fuel supplyl system.

Referring now to Figure 8 there is illustrated yet an,- other embodiment of the present invention in which the lower end of the transfer passage 40 is provided with an outlet port located just lbelow or at the downstream side of the throttle plate 16 in position to be traversed by an edge of the throttle plate during initial opening movement of the throttle. In this case vacuum in the transfer tube is under the control of the throttle 16 as will be readily apparent. With the throttle fully closed as illustrated in Figure 8, vacuum is applied to the passage 40 and hence produces a low pressure at the intake end of the transfer tube. However, the appliedv vacuum will be diminished or cut off uponl predetermined opening movement of the throttle.` Placement of` the port 75 is such that operation of the transfer system is` termi,- nated when the throttle is openedan amount suicient to produce efficient flow of fuel through the main nozzle and eieient mixture of fuel supplied from the main nozzle by means of the normal air velocity alone.

Referring now to Figure 9 there s Aillustrated yet another embodiment of the present invention in which the transfer passage 40 has an outlet port 80 located in position to be substantially closed by an edge of the throttle plate 16 when the throttle plate is in a fully closed position. At this time fuel is supplied to the barrel 10 of the carburetor through the idle fuel supply system including the passage 28 and the port 32. During this idle operation vacuum is not applied to the transfer system. However, initial opening movement of the throttle plate 16 will move the adjacent edge of the throttle plate upstream from the port and will in effect connect the transfer passage 40 to the downstream or low pressure side of the throttle plate. Thus, at a predetermined point in the opening movement of the throttle plate, vacuum is applied to the transfer system and to the intake port 44 located adjacent the main fuel supply means. In this way, vacuum is applied to the transfer system only when it is required to prevent the disadvantages occurring as a result of the inefficient initial stages of operation ofV the main fuel supplyv nozzle.

It will of course be understood that in the embodiments of the invention illustrated in vFigures 6-9 the transfer passages 40 are as shown in Figure 1 and may be connected with transfer tubes 42 having intake ports 44. It will further be understood that the transfer tube 42 and intake ports 44 may be arranged in conjunction with main fuel supply means such as specifically illustrated in Figures l, 3, 4 or 5.

Referring now to Figure l0, there is more or less diagrammatically illustrated a carburetor of the updraft ltype having a barrel 90 in which is located a main fuel supply nozzle 92 and a pivoted throttle plate 93. The main fuel supply nozzle is located in a Venturi 94 as is customary. In this case the transfer system comprises a passage 95 connected to a transfer tube 96 having an intake port 97 adjacent the upstream end of the main fuel supply nozzle 92 in position to collect by vacuum any droplets of liquid fuel collecting thereon before these droplets can be carried in `the air stream into the manifold and thence to the cylinders of the internal combustion engine. ln this case the transfer passage 95 is illustrated as connected to a source of vacuum by a port 98. The port 98 for convenience, is illustrated as similar to the port 80 shown in Figure 9, which is closed by the edge of the throttle plate 9.3 when the throttle is fully closed. Obviously of course, the outlet port connecting the transfer passage 95 to a low pressure source to apply vacuum to the system may be as disclosed in Figures 1, 2, 6, 7, 8 or 9.

Referring againto the embodiment of the invention illustrated in Figures 1 and 2, the operation will be described in some detail. It will be appreciated that the operation of the different embodiments of the invention illustrated in the remaining gures is generally similar and the details of difference are apparent from the description previously given. At the minimum idle speed at which the engine is set to run there is a continuous flow of air entering the intake port 44 of transfer tube 42, proceeding through transfer passage 40 and opening into the end portion 46 of the idle passage. This flow of air serves to improve the atomization of the idle fuel as disclosed in Kittlers copending application, Serial No. 503,468, led April 25, 1955. When the throttle is gradually opened to a point where sucient air ow is induced through the Venturi 14 so that fuel is just beginning to issue from the main discharge nozzle 18, there is encountered the undesirable condition described in the foregoing. It has been observed under test conditions that this fuel will accumulate at the end of the main discharge nozzle 18 or at the lower end of the booster Venturi such as illustrated at 50 in Figure 3, instead of discharging continuously and smoothly into a finely atomized pattern. With the incorporation of the transfer system there is induced an additional air flow `of substantially higher velocity right at the lower edge lof the main nozzle 18. This additional ow of air exerts .a scavenging effect on any particles or droplets of fuel that may collect at the lower edge of the nozzle or booster Venturi. As a result, a fuel-air mixture is drawn through the intake port 44 and thence through the transfer tube 42 and passage 40 where it is admitted into the idle system to blend with the mixture regularly flowing to the idle discharge port 32 from the idle fuel supply passage 28.

It will of course be understood that under the idling and low speed operating conditions herein referred to, there is always a high vacuum existing below the throttle plate 16 so that as a result there will always be a brisk ow of air through the transfer system. Careful observation under test conditions has confirmed that the addition of the transfer tube 40 keeps the lower edge of the main fuel supply or booster Venturi or both, completely free from accumulated drops of fuel and causes this fuel to be aspirated into the transfer system in a smooth continuous fashion, thereby insuring a smooth transfer condition.

When the throttle is opened further there is nally a sufficiently high air velocity through the Venturi and/ or booster Venturi so that the normal spray pattern of fuel issuing from the main nozzle 18 becomes established and the transfer tube automatically diminishes in its effectiveness as the wide open throttle condition is approached. Extensive tests of engines and vehicles equipped with carburetors incorporating this improvement confirm that much leaner mixtures can be used in the transfer range with a resulting improvement in economy. The transfer rangeon present day automobiles is roughly in the region of l5 miles per hour up to approximately 40 miles per hour for the average passenger vehicle. It can be seen that the present invention contributes substantially to the economy and smooth running under these conditions, which encompass a major part of the speed range employed in ordinary city driving.

It is of interest to observe that in a very simple check, the effectiveness of the transfer system has been easily demonstrated. When the air silencer of a carburetor not equipped with the transfer system is removed andthe throttle opened very slowly, the point at which the main nozzle drips fuel can be very easily determined by the intermittent hissing, frying sound made as the droplets of fuel are intermittently drawn past the edge of the throttle plate 16. In contrast to this, a carburetor equipped with the transfer system and subjected to the same test will simply give forth a continuous hissing sound without the frying, crackling noises which are a direct symptom of the intermittent main nozzle fuel discharge.

A further incidental advantage obtained hy the present construction is the substantial reduction in carburetor icing characteristics. This is due to the fact that the vaporization of fuel takes place to a great extent at the point where the transfer passage 40 communicates with the idle fuel supply passage instead of at the edge of the throttle plate. Reduction of temperature resulting fromvaporization `at the juncture between transfer passage 40 and the idle fuel supply passage may be compensated for by proximity to a warm manifold. On the other hand, the loss of heat due to vaporization at the edge of the throttle plate 16 is not so readily overcome by manifold heating at this point and may produce icing.

The drawings and the foregoing specification constitute a description of the improved transfer system in such full, clear, concise and exact terms as to enable any person skilled in the art to practice the invention, the scope of which is indicated by the appended claims.

What we claim as our invention is:

1. In a carburetor comprising a barrel, a main fuel nozzle in said barrel, a main venturi in said barrel, a booster venturi in said barrel surrounding said nozzle and having a downstream annular edge on which drop lets of fuel collect and tend to drip olf, and a throttle plate in said barrel downstream from said nozzle and venturis, the improvement which comprises a passage having a restricted intake port adjacent the downstream edge of said booster venturi, said passage having an outlet port in said barrel in position to be covered by the edge of said throttle plate when it is in closed position but to be exposed to vacuum at the downstream side of said throttle plate whenever said throttle plate is moved away from its closed position, said intake port being in position to suck oi droplets of fuel as they accumulate on the edge of said booster venturi.

2. A carburetor comprising a barrel, fuel supply means in said barrel including a member having an annular lip extending transversely of said barrel and facing downstream thereof on which droplets of fuel accumulate during transition from idle engine operation, a throttle in said barrel downstream from said fuel supply means,

and means for preventing drops of fuel from dripping off said lip into the air stream through said barrel compris-v ing a passage having an outlet port in said barrel in position to be covered by an edge of said throttle when in fully closed position and exposed at the downstream side of said throttle upon initial opening movement of said throttle, said passage having an intake port in immediate proximity to said lip to draw off droplets of fuel therefrom by suction.

3. In a carburetor comprising a barrel, a main fuel supply means comprising a venturi and nozzle and in cluding means having a downstream annular edge on which droplets of fuel tend to collect and drop off during transition from idle engine operation, and a throttle plate in said barrel downstream from said fuel supply means` the improvement which comprises passage means having a discharge and connected to said b arrel in a location such that it is exposed to engine manifold vacuum during transition from engine idle operation, said passage means extending into said barrel and having an inlet port of small area such that engine lmanifold vacuum is effective to establish a strong suction action at said port, said port being located at the downstream side of said annular edge and in close proximity thereto, said inlet port being wholly removed from the center and major portion of the path of fluid flowing from said nozzle whereby suction in said port is adapted to suck olf unvaporized fuel droplets directly from said edge.

4. In a carburetor as defined in cl-aim 3,-a main venturi and a booster venturi, said annular edge forming the downstream end of the booster venturi.

5. In a carburetor as defined in claim 3, the said annular edge extending transversely of said barrel.

6. In a carburetor as dened in claim 3, the discharge end of the passage means being connected to the'barrel downstream from said throttle plate.

7. A carburetor having a barrel, vacuinn operated main fuel supply means therein, a throttle plate therein operable in fully closed position to prevent application of vacuum to said main fuel supply means, said throttle plate being movable from fully closed position toward open position to provide a gradually increasing vacuum to said main fuel Supply meanaandtransfer means con-l nected to a source of vacuum and having an intake port adjacent said main fuel supply means to draw off by lsuction droplets of fuel gathering thereon during transfer from non-operating to operating condition of said main fuel supply means,.said transfer means being connected to a port in said barrel in position to be closed when said throttle plate is fully closed and to be opened at the downstream side of said throttle plate upon initial opening movement thereof.

8. A carburetor for use with an internal combustion engine having an intake manifold, said carburetor comprising a barrel, a main fuel supply means comprising a venturi and nozzle and including means having a downstream annular edge on which droplets of fuel tendto collect and drop off during transition from idle engine operation, a throttle plate in said barrel downstream from said rfuel supply means, a passage having a discharge-'end located such that it is exposed to engine manifold,

vacuum during transition from engine idle operation, said passage extending into said barrel and having an inlet port of small area such that engine manifold vacuum is elfective to establish a strong suction action at said port, said port being located at the downstream side of said annular edge and in close proximity thereto, said inlet port being wholly removed from the center and major portion of the path of fluid flowing from said nozzle whereby suction in said port is adapted to suck off unvaporized yfuel .droplets directly from said edge;

References Cited in the le of this patent UNITED STATES PATENTS 1,863,715 I-Ieitger June 21, 1932: 2,087,293 Olson July 20, 19,37 2,127,444 Emerson Aug. 16, 193.8 2,557,111 Jorgensen et al. June 19, 195,1 2,582,389 McDonnell Ian. 15, 1952 2,705,135 Gehner Mar. 29 19,55 2,711,886 Biver June 28, 1955

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