FUEL-CONTROLLING DEVICE
United States Patent 3592449
An air valve is disposed in the air flowing through a carburetor to the intake manifold of an internal combustion engine. A fuel valve controls the fuel flow to a mixing chamber which produces a suspension of fuel particles which are entrained in the airflow. The air valve is operably connected to the fuel valve through the mixing chamber.
US Patent References:
/1145172.html
Speed - June 1915 - 1145172
/1234227.html
Schmid et al. - July 1917 - 1234227
/1293348.html
Costa - February 1919 - 1293348
/1361529.html
Marr - December 1920 - 1361529
/1376707.html
Leahy et al. - May 1921 - 1376707
/1145172.html
Speed - June 1915 - 1145172
/1234227.html
Schmid et al. - July 1917 - 1234227
/1293348.html
Costa - February 1919 - 1293348
/1361529.html
Marr - December 1920 - 1361529
/1376707.html
Leahy et al. - May 1921 - 1376707
Application Number:
04/750175
Publication Date:
07/13/1971
Filing Date:
08/05/1968
View Patent Images:
Export Citation:
Primary Class:
Other Classes:
261/50.200, 261/44.500
International Classes:
F02M7/17; F02M9/00; F02M9/127; F02M19/12; F02M7/00; F02M19/00; F02M9/02
Field of Search:
261/44,50.1,36.1,DIG.18,DIG.50
US Patent References:
| 1440940 | Carburetor | January 1923 | Smith et al. | |
| 1573065 | Carburetor | February 1926 | Hess | |
| 1595315 | Carburetor | August 1926 | Rayfield | |
| 1789564 | Carburetor | January 1931 | Rayfield | |
| 1792495 | Carburetor | February 1931 | Heath | |
| 1927090 | Carburetor | September 1933 | Hess | |
| 2614581 | Carburetor with automatic air feed control | October 1952 | Russell | |
| 2635625 | Fuel supply device | April 1953 | Moseley et al. | |
| 2757914 | Carburetor | August 1956 | Ball | |
| 3127453 | Floatless carburetor | March 1964 | Sarto | |
| 3275307 | Charge forming device | September 1966 | Robechaud |
Primary Examiner:
Miles, Tim R.
Claims:
I claim
1. A carburetor for an internal combustion engine comprising
1. A carburetor for an internal combustion engine comprising
Description:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention pertains to the field of carburetors for an internal combustion engine in which the airflow into the intake manifold is used to control the flow of fuel to a mixing chamber.
2. Prior Art
It is well known that an internal combustion engine provides maximum power output when the airflow into the intake manifold is at maximum and there is a correct proportion of fuel to air. At any running condition of the engine the ultimate power is decreased if the airflow is less than that demanded by the engine.
Carburetors have been used which include air valves for sensing the airflow and controlling a fuel valve for metering the amount of gas flow into the fuel-air mixing chamber. In the mixing chamber air is mixed with fuel to provide a suspension of fuel particles which are entrained into the airflow and then into the intake manifold of the engine. In such prior carburetors the air valve has been mechanically connected to the fuel-metering valve by rigid rods which were journaled in apertures formed in the carburetor housing. When the power or sped of the engine changed, these rods moved within the journal and there has developed frictional impairment of free axial movement of the rods thereby hampering the correct free response of the gas valve to airflow. On the other hand if the journals were enlarged to minimize friction, fuel in the form of vapor and fuel particles would escape through the enlarged journals from the float chamber to the mixing chamber. This escaping fuel would bypass the fuel-metering pin and seat which controls the air-fuel ratio thereby varying the ratio from a desired value.
Another problem with prior carburetors has been in providing proper damping of the air valve. Without damping, upon change in engine demand for air the air valve would bounce or oscillate above and below the stable or balance position for a substantial period of time which resulted in inefficient operation. It has been known to use a damper plate immersed within the fuel as the damping medium in order to quickly damp out such oscillation. However, if the damping factor is too high, too long a period of time may be required before the balance position is reached. This will increase the lag of time between stepping on or off the accelerator and the response by the engine to increase or decrease power. Such time lag has an adverse effect on the performance of the automobile and in the safety of the operation. Accordingly, prior carburetors have left a lot to be desired in providing an optimum damping factor where the stable position is reached in as short a period of time as possible.
BRIEF OF SUMMARY OF THE INVENTION
In accordance with the invention there is provided a carburetor for an internal combustion engine having a housing with an air intake opening and an output opening. Air flows from the intake opening to the output opening. Fuel and air are mixed in a mixing chamber which produces a suspension of particles of fuel in air which are entrained in the airflow. A fuel valve communicates with a fuel source and is operable to control the flow of fuel to the mixing chamber. An air valve is disposed in the airflow and is movable in accordance with the airflow from the intake to the output opening. The air valve is operably connected to the fuel valve through a coupling which passes through the mixing chamber. In this manner there is avoided the undesirable friction forces of connectors journaled in the carburetor housing.
Further in accordance with the invention the carburetor includes a damper member disposed within a damper housing. The damper member is operably coupled to the fuel valve. Fuel flow between the damper housing and the source of fuel is selectively varied to provide a variable damping factor. In this manner an optimum damping factor may be achieved.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a sectional view of a carburetor of the present inventive concept taken along the section line 1-1 of FIG. 2.
FIG. 2 is a sectional view of the carburetor of FIG. 1 taken along the section line 2-2 of FIG. 1.
FIG. 3 is a sectional view of the portion of the carburetor of FIG. 1 taken along section line 3-3 of FIG. 1.
FIG. 3A is a modification of the invention of FIG. 1 in which a swirl action is produced.
FIGS. 4 and 5 is an exploded perspective view of the air valve, fuel metering and damping system of FIG. 1.
FIG. 6 is a further modification of FIG. 1 in which a floatless chamber is used.
DETAILED DESCRIPTION OF THE DRAWINGS
FIGS. 1--3 show a hollow carburetor housing indicated generally by numeral 10 having an air intake opening 11 and a second mixing chamber 12 which is in communication with a conventional intake manifold (not shown) of an internal combustion engine.
As the engine operates it will produce suction at chamber 12 and therefore air flows into the air intake 11 past a conventional choke valve 14 through chamber 12 and into the intake manifold. An air valve 15 is disposed in the airflow within chamber 12 and as the engine demands more air the air valve senses the weight rate of airflow and moves upwardly. A portion of the airflow passes through the inner opening of valve 15 and the remainder passes between valve 15 and the inner wall of chamber 12.
VALVE 15-- ROD 30-- PIN 34
In the static rest position the annular body 16 of air valve 15 is supported by a valve seat 17 which is adjustably secured by a lock screw 17c to a hollow stem 20 having an enlarged ring-shaped bottom portion 20a. The bottom portion 20a is engaged in an annular shoulder 21 of housing 10 formed at the upper edge of chamber 22 containing fuel.
Air valve 15 includes a spider defined by four straight vertical ribs 15a--d extending inwardly from body 16 with the ribs meeting to form a hollow cylinder 15e. Secured within cylinder 15e is a sleeve 24 having a washer-shaped upper member 24a and a lower portion which may be peened under cylinder 15e. Upper member 24a has four openings in which there are secured respectively the lower ends of rods 25a--d. The upper ends of rods 25a--d are secured within openings 28a--d. The upper ends of rods 25a--d are secured within openings 28a--d respectively of a pin holder 28. Rods 25a--d may be secured to the respective openings of member 24a and holder 28 by welding, as for example. A center opening 28e of pin holder 28 threadedly engages the upper end of a pin rod 30 which extends through without touching a tube 32 and the inner chambers of hollow stem 20. Rod 30 at its lower end, is secured in an opening in an upper end of a fuel valve metering pin 34, the lower end of which is connected to a damper plate 36. Accordingly, metering pin 34 and damper plate 36 move upwardly and downwardly as air valve 15 is urged upwardly and downwardly respectively by the airflow through chamber 12.
Metering pin 34 is tapered so that as it travels in an upward direction the annular clearing between pin 34 and a valve seat 37 threadedly engaged within hollow stem 20, increases in area. In this manner a greater amount of fuel within chamber 22 is allowed to flow into a first mixing chamber 39 formed within stem 20 adjacent to the upper end thereof.
The supply of air for mixing chamber 39 is taken from below valve seat 17 by way of air passages 40. Tube 32 extends upwardly from chamber 39 into chamber 12. In order to provide suction in chamber 39, a pressure difference is produced between the upper and lower sides of air valve 15 which is effective to suck up the mixture of a suspension of fuel particles in the air through tube 32. Accordingly, the mixture is directed out of the upper end of the tube and into the air which flows through second mixing chamber 12 outside of tube 32.
It will now be understood that the only mechanical coupling between air valve 15 and metering pin 34 includes a supporting structure of rods 25a--d and holder 28 and an elongated member or rod 30. Rod 30 extends downwardly through tube 32 and through hollow stem 20 which includes first mixing chamber 39. Accordingly, there is avoided the use of friction producing members which have in the prior art been journaled in apertures in the carburetor housing for coupling the air valve with the metering pin and the damper plate. Alternatively, there is eliminated the amount of fuel which would escape through enlarged journals from the fuel chamber to the mixing chamber bypassing the metering device.
AIR VALVE 15
Inner Opening
Annular body 16 has an inner wall 16a which forms an inner central opening of air valve 15. Wall 16a defines a downwardly and outwardly rounded surface. An annular beveled surface 17a of seat 17 smoothly mates with inner wall 16a when valve 15 is in the static rest position. As air valve 15 moves upwardly, a straight-through smooth streamlined profile for airflow is provided through the inner opening of valve 15 and between seat 17 and valve 15. This streamlined profile is particularly important when valve 15 and seat 17 are substantially close to each other forming a sharp corner to airflow as for example during idle and at low cruise speeds. A sharp corner or nonstreamline profile provides substantially more resistance to airflow than a smooth streamline profile. Thus the major portion of air flowing through the inner opening flow with less resistance as compared with a nonstreamline profile. It will be understood that the boundary layer of air on and adjacent to the inside wall of chamber 12 will be increased in thickness as compared with a nonstreamline profile. Thus the velocity of the air on or adjacent the inside wall is decreased.
Outer Wall
Body 16 has an outer wall 16b adjacent to which inner wall 12a of chamber 12 is inclined in an upwardly and outwardly direction in a manner well known by those skilled in the art. As air valve 15 moves upwardly, the clearing for airflow between outer wall 16b and inner wall 12a increases in area when the lower edge of wall 16b passes the beginning 12b of inclined walls 12a. Accordingly, with valve seat 17 secured to stem 20 by lock screw 17c in the position illustrated, valve 15 travels a substantial distance in response to a minimum demand for air by the engine. At idle speed the engine demands a minimum amount of air and valve 15 is required to travel upwardly until the lower edge of wall 16b passes the beginning 12b of the incline and until the minimum demand for air is satisfied. It will be understood that after the lower edge passes the incline beginning 12b, the air demand is controlled by the slope of the incline. This travel, of substantially a high order of magnitude, is transmitted to pin 34 thereby providing a substantially large area clearing at idle. On the other hand, if valve seat 17 is secured to stem 20 at a position above that illustrated, valve 15 is required to travel upwardly a lower order of magnitude to meet the engine minimum demand for air flow at idle. Accordingly, at idle speed the annular clearing between pin 34 and seat 37 is of substantially less area than in the previous position of seat 17. In this manner, by varying the position of seat 17 the travel of valve 15 may be adjusted to control the fuel air ratio at idle.
Travel Control Leaves
The travel of air valve 15 may also be controlled by adjusting the position of travel control plates or leaves 42a--d, with each of the leaves defining a segment of a flat washer. A slot is formed in each of the leaves 42a--d to receive a screw which is threadedly engaged in an opening formed in the upper surface 16c of body 16. In this manner leaves 42a--d may be adjusted and then rigidly secured in position to determine the effective inside diameter of the central opening of air valve 15.
Guides
In order to guide the movement of air valve 15 there are provided three downwardly extending projections 18a--c from annular body 16. Projections 18a--c include downwardly extending keyways 19a--c respectively for receiving respective guide pins 23a--c secured in chamber 12. In addition a longitudinal keyway 17d is formed in the cylindrical inner wall of seat 17 for receiving a longitudinal key 17e formed on the outer surface of stem 20.
IDLE ADJUST
The fuel-air ratio at idle may be finely adjusted by raising or lowering metering pin 34 while valve 15 is in a static rest position in the following manner. Metering pin 34 is fixedly secured to damper plate 36 which has a notch guide 36a. Guide 36a is engaged by a vertical pin 45 secured to the vertically extending cylinder wall of a cylindrical damper housing 46 surrounding plate 36. The lower end of damper housing 46 is closed and there extends downwardly from the closed end a screwhead 46a which may be turned from the outside of carburetor 10 by inserting a screwdriver in head 46a. Accordingly, by manually turning screwhead 46a, housing 46 is rotated thereby rotating damper plate 36, metering pin 34 and rod 30. Accordingly, as damper plate 36 is rotated the upper end of rod 30 is screwed into or out of threaded opening 28e of holder 28. In this manner metering pin 34 may be raised or lowered with respect to valve seat 37 while valve 15 is in the same static rest position.
VARIABLE DAMPING
Damping of air valve 15 is provided by fuel acting as a damping medium on damper plate 36. As valve 15 and plate 36 go lower, fuel is forced out of the volume of fuel between plate 36 and the lower closed end of housing 46. This fuel flows out through the relatively small clearing 36a forming a fluid connection between the edge of plate 36 and the inner wall of housing 46 into the remaining fuel in chamber 22. Similarly, as valve 15 and plate 37 are raised, fuel flows from chamber 22 through the fluid connection into the space between plate 36 and the closed end of housing 46. It will be understood that this fluid connection is of constant cross-sectional area thereby producing a constant damping factor. In order to provide a variable damping factor, the fluid connection is effectively varied in cross-sectional area thereby to vary the flow of fuel in the following manner.
As best shown in FIGS. 4 and 5, a plurality of equally spaced openings 47 are formed around a circumference of housing 46 adjacent to the lower closed end. A damper control cylinder 50 having a lower closed end 50a receives damper housing 46 with screwhead 46a extending through a central opening in end 50a. An annular shaped shoulder extends horizontally from the lower closed end 50a and has formed therein semicircular slots 50b-c. Screws 51a-b extend through respective slots 50b-c and engage threaded openings on the underside of a bottom base 56. Base 56 is fixedly secured to the bottom edge of housing 10 as for example by screws. It will be understood that base 56 may be an integral part of housing 10. Cylinder 50 may be rotated about its axis by first loosening screws 51a-b and then inserting a spanner wrench in the openings provided. Screws 51a-b are then tightened.
The vertically extending cylindrical wall of cylinder 50 may be about half the height of the wall of housing 46 with an O-ring seal 52 being disposed in sealing relation between the two walls. Below O-ring seal 52 and adjacent openings 57 there are provided in the wall of control cylinder 50 two opposed elongated rectangular openings 54a-b. Base 56 includes a vertically extending cylindrically shaped wall 57 which extends above openings 54a-b. Opposing sections of wall 57 are beveled to form 57a-b. Lines drawn from the ends of sections 57a-b to the centerline of base 56 form angles which may be approximately the same as angles formed by lines drawn from the ends of openings 54a-b to the center of cylinder 50. It will now be understood that an adjustable fluid connection may be traced from the fuel in housing 46 below plate 36 through openings 47 leading to openings 54a and 54b, through beveled sections 57a, 57b, to the fuel within chamber 22. The foregoing adjustable fluid connections are in parallel with each other and with the constant fluid connection through the side of plate 36 to provide a resultant adjustable fluid connection.
In order to adjust the damping, cylinder 50 may be rotated about its axis in the manner previously described so that openings 54a-b are substantially in line with sections 57a-b respectively. In this way there is provided a resultant fluid connection of maximum cross-sectional area thereby to produce minimum damping. On the other hand, cylinder 50 may be rotated so that openings 54a-b are completely covered by vertical nonbeveled walls 57 so that the resultant fluid connection is of minimum cross-sectional area thereby providing maximum damping. It will be understood that damper control cylinder 50 may be turned to positions between the foregoing extreme minimum and maximum damping positions to adjust the damping to an optimum level.
FLOAT CHAMBER 62-- FUEL CHAMBER 22
Fuel is supplied to chamber 22 from a float chamber 62 containing a float 65 by way of fluid connection or pipe 60. Tube 60 has an outlet in chamber 22 adjacent the bottom thereof and an intake opening 60a in chamber 62 which is located in the center of the projected horizontal area of chamber 62. At best shown in FIG. 2 the horizontal projected area of chamber 62 defines a shaped section having curved edges 62a-b and straight edges 62c-d parallel to each other. Intake 60a to be in the center of the projected area is disposed closer to edge 62a than edge 62b and equidistant between parallel edges 62c-d.
By locating intake 60a in the center of the area, it will be understood that when the automobile carrying carburetor 10 tips, the head of fuel at intake 60a is maintained constant. For example, the automobile tips to the right thereby lowering the right end and raising the left end of housing 10. Thus, in chamber 62 the fuel is deeper in the right-hand end than in the left-hand end, but the center of chamber 62 remains constant in depth for a constant head. This constant head is maintained as the automobile tips in any direction. In this manner there is achieved constant static fluid pressure at intake 60a.
The fuel in chamber 22 may not change in depth since the entire chamber is substantially filled with fuel as a result of the fuel level in float chamber 62 being maintained above the top of chamber 22. Accordingly, with a constant static fluid pressure at intake 60a, the static fluid pressure is maintained constant in chamber 22. Accordingly, the fuel feed to metering pin 34 is a function only of the suction produced in mixing chamber 39 and is not dependent on a varying fluid pressure. In this manner more accurate control of the air-fuel mixture is obtained, and therefore there is no cutoff or surge due to the tipping of the carburetor. With a separate float chamber 62 and a fuel chamber 22 containing damper plate 36, there is allowed independent movement of float 65 and plate 36. Specifically, when damper plate 36 rises, it is because the engine requires more fuel from chamber 22 and therefore float 65 may lower to allow more fuel to flow into chamber 62. If theses two actions occur at the same time in the same chamber, as in the prior art, the damper plate prevents the float from swinging freely to feed in fuel. Therefore, an unsteady fuel flow results which causes a hesitation of the engine performance. This hesitation is caused since the flow of fuel into the chamber is in a direction opposite that of damper plate 36. Accordingly, by separating float chamber 62 from chamber 22, there is provided flexibility in allowing the float and the plate to move without producing interfering actions.
Float 65 floats on the surface of the fuel in chamber 62 and has secured thereto the lower end of a float arm 66 which rotates about a pivot 68 and engages the left-hand end of a valve needle 70. When float 65 is at a lower position indicating that fuel is required in chamber 62 the upper end of arm 66 moves to the left, thereby allowing fuel under pressure in inlet 73 to push open valve needle 70 from valve seat 72 and to flow into chamber 62. When float 65 reaches its upper limiting level, the upper end of arm 66 pushes needle 70 to the right against valve seat 72 thereby preventing fuel from flowing into chamber 62. The foregoing float and valving arrangement is adjusted so that the lower fuel level is higher than the top of chamber 22 for the reason previously described. In addition inlet 60a is substantially below the lower fuel level in chamber 62 to assure that no foaming fuel passes into chamber 22.
It will be understood by those skilled in the art that suitable O-ring seals may be provided in sealing relation between cover 56 and chamber 22 and between cylinder 50 and cover 56.
Float chamber 62 illustrated in FIGS. 1 and 2 may be replaced by a floatless constant level chamber 80 as shown in FIG. 6. Carburetors without floats are known in the art and have the advantage of avoiding the use of a float. When a float is damaged for example the carburetor floods and fuel may escape from the carburetor onto the hot manifold causing a fire.
However in prior floatless carburetors the overflow outlet has been connected to the side of a single chamber containing the float and the fuel chamber. Such a single chamber had the disadvantages described above. As illustrated in FIG. 6 a separate floatless chamber 80 is provided for supplying fuel to chamber 22. As in the carburetor of FIGS. 1--5, tube 60 has an outlet in chamber 22 and an intake opening 60a located in the center of the projected horizontal area of chamber 80. A constant flow of fuel enters by way of inlet 82 from a fuel pump (not shown). In this manner fuel fills chamber 80 until it reaches the level of an overflow outlet opening 84 of a tube 85. The overflow fuel flows into opening 84 through overflow tube 85 back to the fuel tank (not shown). Tube 85 extends through a lower opening 88 of chamber 80 and is secured in place by a squeeze fitting 90 threadedly engaged in flange 88a. A gasket is disposed in sealing relation between fitting 90 and opening 88. To change the fuel level tube 85 may be moved upwardly or downwardly by loosening fitting 90 and adjusting tube 85. Opening 84 is always maintained above intake opening 60a.
Outlet opening 84 is located in the center of the projected horizontal area of chamber 80. Thus, as the automobile tips the fuel becomes deeper at one end of chamber 80 with respect to the other end but the center of the area is maintained at a constant depth without the use of a float. Accordingly, the amount of fuel in chamber 80 is maintained constant. As previously described with intake 60a in the center of the projected horizontal area, as the automobile tips a constant head is maintained on opening 60a. In this manner the static fluid pressure is maintained constant in chamber 22 and the fuel feed to metering pin 34 is a function only of the suction produced in mixing chamber 39. Now that the principles of the invention have been explained, it will be understood that many more modifications may be made. For example, the four straight ribs 15a--d forming a spider as shown in FIGS. 1--4 may be twisted at a slight angle from the vertical center line of each rib as illustrated in FIG. 3A. Thus, ribs 15e--h form a slight spiral and these ribs guide the airflow through the inner opening of air valve 15 to produce a small swirl action in the fluid motion in chamber 12. This swirling action in conjunction with the thick boundary layer of air adjacent the inner wall causes the heavier fuel particles in chamber 12 to drop downwardly to be broken into small particles when they meet the fresh air entering from intake 11. Thus there is provided an improved screen for fuel particles.
1. Field of the Invention
This invention pertains to the field of carburetors for an internal combustion engine in which the airflow into the intake manifold is used to control the flow of fuel to a mixing chamber.
2. Prior Art
It is well known that an internal combustion engine provides maximum power output when the airflow into the intake manifold is at maximum and there is a correct proportion of fuel to air. At any running condition of the engine the ultimate power is decreased if the airflow is less than that demanded by the engine.
Carburetors have been used which include air valves for sensing the airflow and controlling a fuel valve for metering the amount of gas flow into the fuel-air mixing chamber. In the mixing chamber air is mixed with fuel to provide a suspension of fuel particles which are entrained into the airflow and then into the intake manifold of the engine. In such prior carburetors the air valve has been mechanically connected to the fuel-metering valve by rigid rods which were journaled in apertures formed in the carburetor housing. When the power or sped of the engine changed, these rods moved within the journal and there has developed frictional impairment of free axial movement of the rods thereby hampering the correct free response of the gas valve to airflow. On the other hand if the journals were enlarged to minimize friction, fuel in the form of vapor and fuel particles would escape through the enlarged journals from the float chamber to the mixing chamber. This escaping fuel would bypass the fuel-metering pin and seat which controls the air-fuel ratio thereby varying the ratio from a desired value.
Another problem with prior carburetors has been in providing proper damping of the air valve. Without damping, upon change in engine demand for air the air valve would bounce or oscillate above and below the stable or balance position for a substantial period of time which resulted in inefficient operation. It has been known to use a damper plate immersed within the fuel as the damping medium in order to quickly damp out such oscillation. However, if the damping factor is too high, too long a period of time may be required before the balance position is reached. This will increase the lag of time between stepping on or off the accelerator and the response by the engine to increase or decrease power. Such time lag has an adverse effect on the performance of the automobile and in the safety of the operation. Accordingly, prior carburetors have left a lot to be desired in providing an optimum damping factor where the stable position is reached in as short a period of time as possible.
BRIEF OF SUMMARY OF THE INVENTION
In accordance with the invention there is provided a carburetor for an internal combustion engine having a housing with an air intake opening and an output opening. Air flows from the intake opening to the output opening. Fuel and air are mixed in a mixing chamber which produces a suspension of particles of fuel in air which are entrained in the airflow. A fuel valve communicates with a fuel source and is operable to control the flow of fuel to the mixing chamber. An air valve is disposed in the airflow and is movable in accordance with the airflow from the intake to the output opening. The air valve is operably connected to the fuel valve through a coupling which passes through the mixing chamber. In this manner there is avoided the undesirable friction forces of connectors journaled in the carburetor housing.
Further in accordance with the invention the carburetor includes a damper member disposed within a damper housing. The damper member is operably coupled to the fuel valve. Fuel flow between the damper housing and the source of fuel is selectively varied to provide a variable damping factor. In this manner an optimum damping factor may be achieved.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a sectional view of a carburetor of the present inventive concept taken along the section line 1-1 of FIG. 2.
FIG. 2 is a sectional view of the carburetor of FIG. 1 taken along the section line 2-2 of FIG. 1.
FIG. 3 is a sectional view of the portion of the carburetor of FIG. 1 taken along section line 3-3 of FIG. 1.
FIG. 3A is a modification of the invention of FIG. 1 in which a swirl action is produced.
FIGS. 4 and 5 is an exploded perspective view of the air valve, fuel metering and damping system of FIG. 1.
FIG. 6 is a further modification of FIG. 1 in which a floatless chamber is used.
DETAILED DESCRIPTION OF THE DRAWINGS
FIGS. 1--3 show a hollow carburetor housing indicated generally by numeral 10 having an air intake opening 11 and a second mixing chamber 12 which is in communication with a conventional intake manifold (not shown) of an internal combustion engine.
As the engine operates it will produce suction at chamber 12 and therefore air flows into the air intake 11 past a conventional choke valve 14 through chamber 12 and into the intake manifold. An air valve 15 is disposed in the airflow within chamber 12 and as the engine demands more air the air valve senses the weight rate of airflow and moves upwardly. A portion of the airflow passes through the inner opening of valve 15 and the remainder passes between valve 15 and the inner wall of chamber 12.
VALVE 15-- ROD 30-- PIN 34
In the static rest position the annular body 16 of air valve 15 is supported by a valve seat 17 which is adjustably secured by a lock screw 17c to a hollow stem 20 having an enlarged ring-shaped bottom portion 20a. The bottom portion 20a is engaged in an annular shoulder 21 of housing 10 formed at the upper edge of chamber 22 containing fuel.
Air valve 15 includes a spider defined by four straight vertical ribs 15a--d extending inwardly from body 16 with the ribs meeting to form a hollow cylinder 15e. Secured within cylinder 15e is a sleeve 24 having a washer-shaped upper member 24a and a lower portion which may be peened under cylinder 15e. Upper member 24a has four openings in which there are secured respectively the lower ends of rods 25a--d. The upper ends of rods 25a--d are secured within openings 28a--d. The upper ends of rods 25a--d are secured within openings 28a--d respectively of a pin holder 28. Rods 25a--d may be secured to the respective openings of member 24a and holder 28 by welding, as for example. A center opening 28e of pin holder 28 threadedly engages the upper end of a pin rod 30 which extends through without touching a tube 32 and the inner chambers of hollow stem 20. Rod 30 at its lower end, is secured in an opening in an upper end of a fuel valve metering pin 34, the lower end of which is connected to a damper plate 36. Accordingly, metering pin 34 and damper plate 36 move upwardly and downwardly as air valve 15 is urged upwardly and downwardly respectively by the airflow through chamber 12.
Metering pin 34 is tapered so that as it travels in an upward direction the annular clearing between pin 34 and a valve seat 37 threadedly engaged within hollow stem 20, increases in area. In this manner a greater amount of fuel within chamber 22 is allowed to flow into a first mixing chamber 39 formed within stem 20 adjacent to the upper end thereof.
The supply of air for mixing chamber 39 is taken from below valve seat 17 by way of air passages 40. Tube 32 extends upwardly from chamber 39 into chamber 12. In order to provide suction in chamber 39, a pressure difference is produced between the upper and lower sides of air valve 15 which is effective to suck up the mixture of a suspension of fuel particles in the air through tube 32. Accordingly, the mixture is directed out of the upper end of the tube and into the air which flows through second mixing chamber 12 outside of tube 32.
It will now be understood that the only mechanical coupling between air valve 15 and metering pin 34 includes a supporting structure of rods 25a--d and holder 28 and an elongated member or rod 30. Rod 30 extends downwardly through tube 32 and through hollow stem 20 which includes first mixing chamber 39. Accordingly, there is avoided the use of friction producing members which have in the prior art been journaled in apertures in the carburetor housing for coupling the air valve with the metering pin and the damper plate. Alternatively, there is eliminated the amount of fuel which would escape through enlarged journals from the fuel chamber to the mixing chamber bypassing the metering device.
AIR VALVE 15
Inner Opening
Annular body 16 has an inner wall 16a which forms an inner central opening of air valve 15. Wall 16a defines a downwardly and outwardly rounded surface. An annular beveled surface 17a of seat 17 smoothly mates with inner wall 16a when valve 15 is in the static rest position. As air valve 15 moves upwardly, a straight-through smooth streamlined profile for airflow is provided through the inner opening of valve 15 and between seat 17 and valve 15. This streamlined profile is particularly important when valve 15 and seat 17 are substantially close to each other forming a sharp corner to airflow as for example during idle and at low cruise speeds. A sharp corner or nonstreamline profile provides substantially more resistance to airflow than a smooth streamline profile. Thus the major portion of air flowing through the inner opening flow with less resistance as compared with a nonstreamline profile. It will be understood that the boundary layer of air on and adjacent to the inside wall of chamber 12 will be increased in thickness as compared with a nonstreamline profile. Thus the velocity of the air on or adjacent the inside wall is decreased.
Outer Wall
Body 16 has an outer wall 16b adjacent to which inner wall 12a of chamber 12 is inclined in an upwardly and outwardly direction in a manner well known by those skilled in the art. As air valve 15 moves upwardly, the clearing for airflow between outer wall 16b and inner wall 12a increases in area when the lower edge of wall 16b passes the beginning 12b of inclined walls 12a. Accordingly, with valve seat 17 secured to stem 20 by lock screw 17c in the position illustrated, valve 15 travels a substantial distance in response to a minimum demand for air by the engine. At idle speed the engine demands a minimum amount of air and valve 15 is required to travel upwardly until the lower edge of wall 16b passes the beginning 12b of the incline and until the minimum demand for air is satisfied. It will be understood that after the lower edge passes the incline beginning 12b, the air demand is controlled by the slope of the incline. This travel, of substantially a high order of magnitude, is transmitted to pin 34 thereby providing a substantially large area clearing at idle. On the other hand, if valve seat 17 is secured to stem 20 at a position above that illustrated, valve 15 is required to travel upwardly a lower order of magnitude to meet the engine minimum demand for air flow at idle. Accordingly, at idle speed the annular clearing between pin 34 and seat 37 is of substantially less area than in the previous position of seat 17. In this manner, by varying the position of seat 17 the travel of valve 15 may be adjusted to control the fuel air ratio at idle.
Travel Control Leaves
The travel of air valve 15 may also be controlled by adjusting the position of travel control plates or leaves 42a--d, with each of the leaves defining a segment of a flat washer. A slot is formed in each of the leaves 42a--d to receive a screw which is threadedly engaged in an opening formed in the upper surface 16c of body 16. In this manner leaves 42a--d may be adjusted and then rigidly secured in position to determine the effective inside diameter of the central opening of air valve 15.
Guides
In order to guide the movement of air valve 15 there are provided three downwardly extending projections 18a--c from annular body 16. Projections 18a--c include downwardly extending keyways 19a--c respectively for receiving respective guide pins 23a--c secured in chamber 12. In addition a longitudinal keyway 17d is formed in the cylindrical inner wall of seat 17 for receiving a longitudinal key 17e formed on the outer surface of stem 20.
IDLE ADJUST
The fuel-air ratio at idle may be finely adjusted by raising or lowering metering pin 34 while valve 15 is in a static rest position in the following manner. Metering pin 34 is fixedly secured to damper plate 36 which has a notch guide 36a. Guide 36a is engaged by a vertical pin 45 secured to the vertically extending cylinder wall of a cylindrical damper housing 46 surrounding plate 36. The lower end of damper housing 46 is closed and there extends downwardly from the closed end a screwhead 46a which may be turned from the outside of carburetor 10 by inserting a screwdriver in head 46a. Accordingly, by manually turning screwhead 46a, housing 46 is rotated thereby rotating damper plate 36, metering pin 34 and rod 30. Accordingly, as damper plate 36 is rotated the upper end of rod 30 is screwed into or out of threaded opening 28e of holder 28. In this manner metering pin 34 may be raised or lowered with respect to valve seat 37 while valve 15 is in the same static rest position.
VARIABLE DAMPING
Damping of air valve 15 is provided by fuel acting as a damping medium on damper plate 36. As valve 15 and plate 36 go lower, fuel is forced out of the volume of fuel between plate 36 and the lower closed end of housing 46. This fuel flows out through the relatively small clearing 36a forming a fluid connection between the edge of plate 36 and the inner wall of housing 46 into the remaining fuel in chamber 22. Similarly, as valve 15 and plate 37 are raised, fuel flows from chamber 22 through the fluid connection into the space between plate 36 and the closed end of housing 46. It will be understood that this fluid connection is of constant cross-sectional area thereby producing a constant damping factor. In order to provide a variable damping factor, the fluid connection is effectively varied in cross-sectional area thereby to vary the flow of fuel in the following manner.
As best shown in FIGS. 4 and 5, a plurality of equally spaced openings 47 are formed around a circumference of housing 46 adjacent to the lower closed end. A damper control cylinder 50 having a lower closed end 50a receives damper housing 46 with screwhead 46a extending through a central opening in end 50a. An annular shaped shoulder extends horizontally from the lower closed end 50a and has formed therein semicircular slots 50b-c. Screws 51a-b extend through respective slots 50b-c and engage threaded openings on the underside of a bottom base 56. Base 56 is fixedly secured to the bottom edge of housing 10 as for example by screws. It will be understood that base 56 may be an integral part of housing 10. Cylinder 50 may be rotated about its axis by first loosening screws 51a-b and then inserting a spanner wrench in the openings provided. Screws 51a-b are then tightened.
The vertically extending cylindrical wall of cylinder 50 may be about half the height of the wall of housing 46 with an O-ring seal 52 being disposed in sealing relation between the two walls. Below O-ring seal 52 and adjacent openings 57 there are provided in the wall of control cylinder 50 two opposed elongated rectangular openings 54a-b. Base 56 includes a vertically extending cylindrically shaped wall 57 which extends above openings 54a-b. Opposing sections of wall 57 are beveled to form 57a-b. Lines drawn from the ends of sections 57a-b to the centerline of base 56 form angles which may be approximately the same as angles formed by lines drawn from the ends of openings 54a-b to the center of cylinder 50. It will now be understood that an adjustable fluid connection may be traced from the fuel in housing 46 below plate 36 through openings 47 leading to openings 54a and 54b, through beveled sections 57a, 57b, to the fuel within chamber 22. The foregoing adjustable fluid connections are in parallel with each other and with the constant fluid connection through the side of plate 36 to provide a resultant adjustable fluid connection.
In order to adjust the damping, cylinder 50 may be rotated about its axis in the manner previously described so that openings 54a-b are substantially in line with sections 57a-b respectively. In this way there is provided a resultant fluid connection of maximum cross-sectional area thereby to produce minimum damping. On the other hand, cylinder 50 may be rotated so that openings 54a-b are completely covered by vertical nonbeveled walls 57 so that the resultant fluid connection is of minimum cross-sectional area thereby providing maximum damping. It will be understood that damper control cylinder 50 may be turned to positions between the foregoing extreme minimum and maximum damping positions to adjust the damping to an optimum level.
FLOAT CHAMBER 62-- FUEL CHAMBER 22
Fuel is supplied to chamber 22 from a float chamber 62 containing a float 65 by way of fluid connection or pipe 60. Tube 60 has an outlet in chamber 22 adjacent the bottom thereof and an intake opening 60a in chamber 62 which is located in the center of the projected horizontal area of chamber 62. At best shown in FIG. 2 the horizontal projected area of chamber 62 defines a shaped section having curved edges 62a-b and straight edges 62c-d parallel to each other. Intake 60a to be in the center of the projected area is disposed closer to edge 62a than edge 62b and equidistant between parallel edges 62c-d.
By locating intake 60a in the center of the area, it will be understood that when the automobile carrying carburetor 10 tips, the head of fuel at intake 60a is maintained constant. For example, the automobile tips to the right thereby lowering the right end and raising the left end of housing 10. Thus, in chamber 62 the fuel is deeper in the right-hand end than in the left-hand end, but the center of chamber 62 remains constant in depth for a constant head. This constant head is maintained as the automobile tips in any direction. In this manner there is achieved constant static fluid pressure at intake 60a.
The fuel in chamber 22 may not change in depth since the entire chamber is substantially filled with fuel as a result of the fuel level in float chamber 62 being maintained above the top of chamber 22. Accordingly, with a constant static fluid pressure at intake 60a, the static fluid pressure is maintained constant in chamber 22. Accordingly, the fuel feed to metering pin 34 is a function only of the suction produced in mixing chamber 39 and is not dependent on a varying fluid pressure. In this manner more accurate control of the air-fuel mixture is obtained, and therefore there is no cutoff or surge due to the tipping of the carburetor. With a separate float chamber 62 and a fuel chamber 22 containing damper plate 36, there is allowed independent movement of float 65 and plate 36. Specifically, when damper plate 36 rises, it is because the engine requires more fuel from chamber 22 and therefore float 65 may lower to allow more fuel to flow into chamber 62. If theses two actions occur at the same time in the same chamber, as in the prior art, the damper plate prevents the float from swinging freely to feed in fuel. Therefore, an unsteady fuel flow results which causes a hesitation of the engine performance. This hesitation is caused since the flow of fuel into the chamber is in a direction opposite that of damper plate 36. Accordingly, by separating float chamber 62 from chamber 22, there is provided flexibility in allowing the float and the plate to move without producing interfering actions.
Float 65 floats on the surface of the fuel in chamber 62 and has secured thereto the lower end of a float arm 66 which rotates about a pivot 68 and engages the left-hand end of a valve needle 70. When float 65 is at a lower position indicating that fuel is required in chamber 62 the upper end of arm 66 moves to the left, thereby allowing fuel under pressure in inlet 73 to push open valve needle 70 from valve seat 72 and to flow into chamber 62. When float 65 reaches its upper limiting level, the upper end of arm 66 pushes needle 70 to the right against valve seat 72 thereby preventing fuel from flowing into chamber 62. The foregoing float and valving arrangement is adjusted so that the lower fuel level is higher than the top of chamber 22 for the reason previously described. In addition inlet 60a is substantially below the lower fuel level in chamber 62 to assure that no foaming fuel passes into chamber 22.
It will be understood by those skilled in the art that suitable O-ring seals may be provided in sealing relation between cover 56 and chamber 22 and between cylinder 50 and cover 56.
Float chamber 62 illustrated in FIGS. 1 and 2 may be replaced by a floatless constant level chamber 80 as shown in FIG. 6. Carburetors without floats are known in the art and have the advantage of avoiding the use of a float. When a float is damaged for example the carburetor floods and fuel may escape from the carburetor onto the hot manifold causing a fire.
However in prior floatless carburetors the overflow outlet has been connected to the side of a single chamber containing the float and the fuel chamber. Such a single chamber had the disadvantages described above. As illustrated in FIG. 6 a separate floatless chamber 80 is provided for supplying fuel to chamber 22. As in the carburetor of FIGS. 1--5, tube 60 has an outlet in chamber 22 and an intake opening 60a located in the center of the projected horizontal area of chamber 80. A constant flow of fuel enters by way of inlet 82 from a fuel pump (not shown). In this manner fuel fills chamber 80 until it reaches the level of an overflow outlet opening 84 of a tube 85. The overflow fuel flows into opening 84 through overflow tube 85 back to the fuel tank (not shown). Tube 85 extends through a lower opening 88 of chamber 80 and is secured in place by a squeeze fitting 90 threadedly engaged in flange 88a. A gasket is disposed in sealing relation between fitting 90 and opening 88. To change the fuel level tube 85 may be moved upwardly or downwardly by loosening fitting 90 and adjusting tube 85. Opening 84 is always maintained above intake opening 60a.
Outlet opening 84 is located in the center of the projected horizontal area of chamber 80. Thus, as the automobile tips the fuel becomes deeper at one end of chamber 80 with respect to the other end but the center of the area is maintained at a constant depth without the use of a float. Accordingly, the amount of fuel in chamber 80 is maintained constant. As previously described with intake 60a in the center of the projected horizontal area, as the automobile tips a constant head is maintained on opening 60a. In this manner the static fluid pressure is maintained constant in chamber 22 and the fuel feed to metering pin 34 is a function only of the suction produced in mixing chamber 39. Now that the principles of the invention have been explained, it will be understood that many more modifications may be made. For example, the four straight ribs 15a--d forming a spider as shown in FIGS. 1--4 may be twisted at a slight angle from the vertical center line of each rib as illustrated in FIG. 3A. Thus, ribs 15e--h form a slight spiral and these ribs guide the airflow through the inner opening of air valve 15 to produce a small swirl action in the fluid motion in chamber 12. This swirling action in conjunction with the thick boundary layer of air adjacent the inner wall causes the heavier fuel particles in chamber 12 to drop downwardly to be broken into small particles when they meet the fresh air entering from intake 11. Thus there is provided an improved screen for fuel particles.