US3494750A

US3494750A - Gaseous fuel carburetor

Info

Publication number: US3494750A
Application number: US610854A
Authority: US
Inventors: Jack R Phipps
Original assignee: Bendix Corp
Current assignee: Bendix Corp
Priority date: 1967-01-23
Filing date: 1967-01-23
Publication date: 1970-02-10
Anticipated expiration: 1987-02-10

Description

I5 Sheets-Sheet l INVENTOR.

JACK R. PHIPPS J. R. PHIPPS GASEOUS FUEL CARBUREIOE Feb. 10, 1970 Filed Jan. 23, 1967 FIG.

Feb; 10, 1970 J. R. PHIPPS GASEOUS FUEL .CARBURETOR 3 Sheets-Sheet 2 Filed Jan. 23, 1967 FIG. 4

United States Patent 3,494,750 GASEOUS FUEL CARBURETOR Jack R. Phipps, St. Clair Shores, Mich., assignor to The Bendix Corporation, a corporation of Delaware Filed Jan. 23, 1967, Ser. No. 610,854 Int. Cl. B01f 3/02 US. Cl. 48-184 11 Claims ABSTRACT OF THE DISCLOSURE A gaseous fuel carburetor having a port at the venturi for sensing flow therethrough in combination with a fuel discharge port spaced along the induction passage from the venturi port.

The present invention relates to carburetors and more particularly to a carburetor for liquefied petroleum gas for internal combustion engines.

In the conventional carburetor for liquefied petroleum gas for internal combustion engines, the supply of gas is regulated by a series of diaphragms responsive to pressures at various points in the carburetor induction passage, particularly at the venturi, and the gas is metered and normally discharged into the throat of the venturi. Since one of the principal pressures employed in regulating the flow of gas is the venturi, the discharge of gas into the venturi tends to disrupt performance of the regulator and metering system and has resulted in a tendency for the fuel in the fuel-air ratio to become less at a time when an increase in the fuel is normally required. While the foregoing adverse condition has long been recognized in the industry, the advantages of discharging the gas into the air at the venturi to obtain effective distribution of the gas in the air flow have outweighed the disadvantages of poor or improper control of the regulator, since these difiiculties or deficiencies can be and have been compensated for by additional means in the carburetor to provide the correct fuel-air ratio under all normal operating conditions. These additional means, however, have rendered the carburetor rather complicated and difiicult to adjust and service, and have often resulted in erratic and unreliable performance and poor response to variations in engine operating conditions. It is, therefore, one of the principal objects of the present invention to provide a carburetor for gaseous fuel which utilizes the pressure in the venturi as one of its primary control pressures for the regulation, and which is so constructed and arranged that the discharge of fuel into the induction passage does not adversely affect venturi pressure sensed by the regulator.

Another object of the invention is to provide a carburetor for gaseous fuel, which senses the pressure of the venturi but which discharges the fuel into the air stream anterior thereto, thus permitting the venturi to respond to the flow of the fuel-air mixture rather than merely the air flow, and thereby obtaining optimum performance with a minimum number of systems and metering correction features.

A further object of the invention is to provide a carburetor for gaseous fuel of the aforesaid type which accurately regulates and meters the fuel in response to venturi pressure, and which provides effective distribution of the fuel in the air flowing through the carburetor.

Additional objects and advantages of the invention will become apparent from the following description and accompanying drawings, wherein:

FIGURE 1 is a top plan view of the present carburetor;

FIGURE 2 is a vertical cross-sectional view of the carburetor, the section being taken on line 22 of FIG- URE 1;

FIGURE 3 is in effect a vertical cross-sectional view taken on line 3-3 of FIGURE 2, actually being an elevational view with a portion of the regulator removed from the body of the carburetor;

FIGURE 4 is a horizontal cross-sectional view of the carburetor, the section being taken on line 4-4 of FIG- URE 3;

FIGURE 5 is a vertical cross-sectional view taken on line 55 of FIGURE 1;

FIGURE 6 is an enlarged fragmentary vertical crosssectional view of the carburetor taken on line 66 of FIGURE 1;

FIGURE 7 is an enlarged fragmentary cross-sectional view taken on line 77 of FIGURE 2, and;

FIGURE 8 is an enlarged fragmentary vertical crosssectional view taken on line 88 of FIGURE 1.

Referring more specifically to the drawings, and to FIGURES 1 and 2 in particular, numeral 10 designates the body of the carburetor having an inlet passage or air horn 12, venturi 14 and throttle body 16, having mounted therein throttle 18 on shaft 20 journaled in the side wall of the throttle body. A flange 22 is formed integrally with the throttle body and is provided with holes 24 and 26 for receiving screws for securing the carburetor to the inlet of the intake manifold of an internal combustion engine (not shown). The air horn contains a choke valve 28 mounted on a shaft 30 which, in turn, is journaled in the sidewall of the air horn, the air horn normally being provided with an air filter secured to the external wall thereof. The carburetor thus far described may, for the purpose of the present description, be considered conventional in construction.

A fuel regulator is mounted on the side of the carburetor body and is secured thereto by a plurality of screws 42 extending through the regulator into the body structure. The regulator consists of three

principal sections

44, 46 and 48 containing

chambers

50, 52 and 54, respectively.

Chambers

50 and 52 are separated by a flexible diaphragm 56 and

chambers

52 and 54 are separated by a diaphragm 58, the diaphragms being clamped in sealing relationship between the walls of the respective sections, and held securely in place by screws 59, Chamber 50 is connected to the fuel inlet passage 60 which, in turn, is connected to a source of fuel, such as a cylinder wherein the gaseous petroleum is maintained under suflicient pressure to liquefy the gas. A pressure regulator and vaporizer (not shown) are normally in the line between the source and inlet passage. The fuel is delivered to fuel inlet '60 in a gaseous form and is controlled by an inlet valve 62 consisting of element 64 joined to an arm 66 which is pivoted to move valve element 64 to and from its seat 70 on the upper end of inlet passage 60. The valve 62 and arm 66 are pivoted on a leaf spring member 72 secured to the wall of section 44 by screws 74. Lever 66 is urged in the direction to seat valve element 64 onto seat 70 by a coil spring reacting between the side of the carburetor body and the upper end of the lever.

The valve is controlled by pressures in the carburetor transmitted to

chambers

52 and 54 and acting on

diaphragms

56 and 58, diaphragm 56 having a center lug 82 for contacting a projection 84 on lever 66. Diaphragm 58 is operatively connected to the lever by a member 86 attached to the diaphragm 56 and engaging the reinforcing member 88 of diaphragm 58, the reinforcing member being secured to the latter diaphragm by a rivet construction 90. Chamber 52 is connected to the throat of venturi 14 by a passage 92 in

sections

46, 44 and the carburetor body 10, and port 94 in the venturi, and hence

diaphragms

56 and 58 are subjected to and principally controlled by the variations in suction in the venturi. Chamber 54 is connected to inlet passage 12 in the air horn by port 100,

passage 102 and port 104 in the carburetor body and in

sections

46 and 48, a restriction 106 preferably being provided in passage 102. It is thus seen that diaphragm 56.is partially controlled by inlet pressure, which Will remain substantially constant throughout most of the operation of the engine. However, variations in pressure will occur in the event the air cleaner becomes partially clogged with foreign matter, and to a slight extent from impact pressure from the effect of air flow on port 100.

Gaseous fuel on leaving inlet passage 60 passes into chamber 50 and thence through passage 110 to metering valve 112 and discharge jet 114, the valve 112 :being adjusted by screw 116 threadedly received in valveboss 118. The position of jet 114 is in substantially direct alignment with the center of the venturi and discharges the fuel into the air as it leaves the air horn and is approaching the entrance to the venturi. As can be seen in the drawings, the jet 114 is located a significant distance longitudinally along the induction passage from the pressure sensing port Q4. At this point the air flow is relatively turbulent and hence the gaseous fuel is readily dispersed, distributed and mixed in the air to form an effective combustible. mixture. The fuel-air mixture thus formed passes through the venturi where the flow thereof is sensed through port 94 and passage 92 by

diaphragms

58 and 56. As the flow through the venturi is increased and the pressure at the throat thus decreases, diaphragm 58 moves to the left as viewed in FIGURE 2, urging lever 66 to the left, thereby further opening valve 64 and admitting a greater quantity of fuel to mix with the greater quantity of air passing through the carburetor to the engine. The movement of diaphragm 58 and lever 66 to the left is opposed by spring 80 which returns the diaphragm and lever to their original position as the air flow in the venturi decreases.

The present fuel system may include a back suction economizer, such as that illustrated in FIGURE 8, in which a port 120 is in the induction passage adjacent the throttle valve on the air intake side thereof, when the valve is connected to chamber 54 by

passages

122 and 102. When the throttle is opened for acceleration, the adjacent edge of the throttle passes port 120, permitting the port to communicate with the engine side of the throttle, and hence transmit manifold vacuum through passage 122 and to chamber 54. Passage .122 is connected to passage 102, which in turn is connected to chamber 54; thus, as the throttle is opened and manifold vacuum transmitted through port 120 and through

passages

122 and 102 to chamber 54, diaphragm 58 moves to the right, as viewed in FIGURE 2, permitting spring 80 to move valve 64 further toward closed position and thus reducing the amount of fuel delivered to the engine. As the throttle valve is moved to substantially wide open position during acceleration, the drop in pressure in the manifold is relatively small and the vacuum transmitted to chamber 54 has little effect on decreasing the amount of fuel which otherwise would be delivered to the engine.

The idle system is connected to chamber 50 and consists of a passage 130, a discharge jet 131, and an idle valve 132, the idle valve being adjustable toward and away from jet 131 by thumbscrew 134 threadedly received in boss 136 and held in adjusted position by spring 138. An air bleed 140 is provided on the air intake side of throttle valve 18 which assists in forming an efl ective fuel-air mixture discharged through jet 131. When the engine is idling, air. is drawn into chamber 50 through orifice 142 and orifice 114 and mixes with the gaseous fuel in chamber 50. This rich fuel mixture flows through passage 130 where it mixes with additional air from port 140 and is then discharged through jet 131. As the throttle is opened, it passes port 140, thus rendering the port ineffective as a supply of air for the idle system and permitting the amount of fuel discharged through the idle system to be increased to compensate for the increased air flow until the main jet 114 and orifice 142 become operable to supply the required fuel.

In the operation of the foregoing carburetor starting with the throttle valve in closed position and the engine running, fuel is supplied to the carburetor through the idle system with air flowing through chamber 50 through

orifices

142 and 114 into chamber 50 and thence through the idle system to discharge jet 131. Manifold vacuum transmitted through passage to chamber 50 causes diaphragm 56 to open valve 64 sufliciently to supply the fuel needed for idling. When the throttle valve is opened, the air flow through the venturi creates a vacuum therein which is transmitted to chamber 52 where it, acting upon

diaphragms

56, and 58, moves lever 66 to the left as viewed in FIGURE 2, thereby further opening metering valve 64. The diaphragm 58 being substantially larger in area than diaphragm 56, causes the two diaphragms to move to the left when the pressure therebetween is decreased sufliciently to overcome the fuel pressure in chamber 50. The vacuum from the venturi is balanced against the fuel pressure in chamber 50 and against air inlet pressure transmitted to chamber 54, permitting the carburetor to regulate the flow of fuel to obtain the proper fuel-air ratio, irrespective of variations in inlet pressure of the fuel or inlet pressure of the air, and thus maintaining the proper fuel ratio under all variations in operating conditions. As the throttle valve is opened beyond port 120, the richness of the fuel-air mixture is decreased by the back suction effect created in chamber 54, thus obtaining a somewhat leaner mixture during normal operation of the engine. When the throttle valve is moved to substantially wide open position, the effect of the back suction on diaphragm 58 becomes insignificant and a relatively rich mixture is hence supplied to the engine for high power output.

While only one embodiment of the present invention has been described in detail herein, various changes and modifications may be made to suit requirements.

I claim:

1. A carburetor for gaseous fuel, comprising a body having an induction passage with an air inlet and a fuelair mixture outlet, a throttle in said passage, a venturi in said passage anterior to said throttle, a fuel inletmeans, a fuel discharge port in said induction passage anterior to said venturi, a fuel passage connecting said fuel inlet means with said discharge port, a valve in said fuel passage, pressure sensing means at said venturi for sensing venturi suction created by the flow of fuel-air mixture through said venturi, and a regulating means operatively associated with said pressure sensing means for controlling said valve substantially according to said venturi suction, whereby the location of said discharge port prevents the discharge of fuel from adversely affecting the sensing of flow-created suction by said pressure sensing means.

-2. A carburetor as defined in claim 1 in which the carburetor has an induction passage with a horizontal inlet portion and a vertical portion containing the venturi, and in which said fuel discharge port is positioned in substantially axial alignment with said venturi.

3. A carburetor as defined in claim 1 in which an idle system conduit connects said fuel passage with the induction passage on the posterior side of the throttle.

4. A carburetor as defined in claim 1 in which said pressure sensing means includes a port in said venturi and said regulating means includes a housing having in series a gaseous fuel chamber connected to said fuel inlet means, a chamber connected to said pressure sensing port in said venturi, and a chamber connected to the induction passage inlet, and diaphragms separating said chambers and being operatively connected to said valve, the diaphragm separating said venturi pressure chamber and said air inlet chamber being larger in area than the diaphragm separating said fuel chamber from said venturi pressure chamber.

5. A carburetor as defined in claim 4 in which the carburetor has an induction passage with a horizontal inlet portion and a vertical portion containing the venturi,

and in which said fuel discharge port is positioned in substantially axial alignment with said venturi.

6. A carburetor as defined in claim 5 in which an idle system conduit connects said fuel passage with the induction passage on the posterior side of the throttle valve.

7. A carburetor as defined in claim 6 in which the chamber in said housing subjected to air inlet pressure includes a passage connected to the induction passage anterior and adjacent to said throttle valve in a position to create a back suction condition in said air inlet pressure chamber when said throttle valve is partly opened.

8. A carburetor as defined in claim 4 in which the chamber in said housing subjected to air inlet pressure includes a passage connected to the induction passage anterior and adjacent to said throttle valve in a position to create a back suction condition in said air inlet pressure chamber When said throttle valve is partly opened.

9. A carburetor as defined in claim 4 in Which said valve includes an operating lever and a spring urging said lever in the direction to close said valve in opposition to the pressure on said diaphragms.

10. A carburetor as defined in claim 9 in which said valve and lever are pivoted on a leaf spring.

11. A carburetor for gaseous fuel, comprising a body having an induction passage with an air inlet and a fuelair mixture outlet, 21 throttle in said passage, a venturi in said passage anterior to said throttle, pressure sensing means at said venturi for sensing flow through said venturi, a fuel inlet means, a fuel discharge port in said induction passage anterior to and spaced a predetermined distance longitudinally along said induction passage from said pressure sensing means to prevent the discharge of said gaseous fuel from adversely affecting flow sensing by said pressure sensing means, a fuel passage connecting said fuel inlet means with said discharge port, valve means in said fuel passage for controlling the flow of fuel therethrough, and a regulating means operatively associated with said pressure sensing means for controlling said valve substantially according to said flow through said venturi.

References Cited UNITED STATES PATENTS 1,436,690 11/1922 Secor 48180 2,209,206 7/ 1940 Peduzzi 481 4 2,346,763 4/1944 Jones 48-180 3,009,794 11/1961 Barfod 48184 3,068,085 12/1962 Ensign et al. 48-184 JOSEPH SCOVRONEK, Primary Examiner US. Cl. X.R.