Multi carburetor system of variable area venturi type with auxiliary fuel supply system

Claim 2

An auxiliary fuel supply system for use with a multi carburetor system of the variable area venturi type for an internal combustion engine having an air cleaner, a float chamber, a carburetor induction passage leading from said air cleaner into intake manifolds of said engine, a throttle valve disposed in said carburetor induction passage and adapted to be fully closed during idling and decelerating operations of said engine, a variable area venturi formed in said carburetor induction passage and including a constriction and an air flow control assembly to continuously reduce the effective sectional area at the venturi as said throttle valve closes, and a balance tube connected between said intake manifolds of said engine and communicating with said carburetor induction passage downstream of said throttle valve, said auxiliary fuel supply system comprising means for defining main passage communicating with said intake manifolds through said balance tube extending therebetween to supply said engine with an air-fuel mixture of optimum amount and mixture ratio for satisfactory combustion when said throttle valve is fully closed during idling and decelerating conditions of said engine, means for defining slow running mixture circuit communicating with said main passage for supplying an air-fuel mixture of optimum mixture ratio through said main passage to said intake manifolds when said throttle valve is fully closed during idling operation of said engine, means for defining deceleration circuit communicating with said main passage for supplying an air-fuel mixture to be mixed with said air-fuel mixture supplied from said slow running mixture circuit to form a combustible air-fuel mixture when said throttle valve is fully closed during decelerating operation of said engine, valve means disposed in said deceleration mixture circuit, and control means responsive to an intake manifold vacuum of said engine for controlling said valve means to open said deceleration circuit when said intake manifold vacuum reaches a predetermined value during decelerating operation of said engine.

Claim 3

An auxiliary fuel supply system according to claim 1, wherein said means for defining main passage has a main air inlet leading to an air chamber communicating with said air cleaner, and a main adjust screw disposed in said main air inlet for controlling the flow of air flowing into said main passage thereby to adjust the mixture ratio of said air-fuel mixture in said main passage.

Claim 4

An auxiliary fuel supply system according to claim 1, wherein said means for definIng slow running mixture circuit consists of a slow running air bleed vented to the atmosphere and a slow running fuel jet provided upstream of said slow running air bleed and leading to a fuel supply chamber communicating with said float chamber, the effective areas of said slow running air bleed and said slow running fuel jet being determined to admit a suitable amount of air and fuel into said slow running mixture circuit to provide an air-fuel mixture of optimum mixture ratio for the idling operation of said engine.

Claim 5

An auxiliary fuel supply system according to claim 3, wherein said slow running mixture circuit includes a slow running port opening to said main passage and a slow running adjust screw disposed therein for controlling the amount of air-fuel mixture to be admitted to said main passage.

Claim 6

An auxiliary fuel supply system according to claim 3, wherein said means for defining deceleration mixture circuit consists of a deceleration air bleed leading from said air chamber, and a deceleration fuel jet provided in said deceleration mixture circuit downstream of said deceleration air bleed and communicating with said fuel supply chamber, the effective areas of said deceleration air bleed and said deceleration fuel jet being calibrated to admit air and fuel into said deceleration mixture circuit to provide an air-fuel mixture to be mixed in said main passage with said air-fuel mixture supplied from said slow running mixture circuit to provide a combustible mixture during decelerating operation of said engine.

Claim 7

An auxiliary fuel supply system according to claim 5, wherein said deceleration mixture circuit includes a deceleration port opening to said main passage, said deceleration port being opened and closed by said valve means. diaphragm

Claim 8

An auxiliary fuel supply system according to claim 1, wherein said control means includes first and second vacuum chambers, said first vacuum chamber having an outlet passage communicating with said main passage, wall means intervening between said first and second vacuum chambers and having formed therein a valve opening interconnecting said first and second vacuum chambers with respect to each other, first diaphragm means disposed in said first vacuum chamber, a valve element attached to said first diaphragm means and extending through said valve opening formed in said wall means, a first compression spring dispoed in said first vacuum chamber for biasing said first diaphragm means to a position in which said valve element closes said valve opening, a second diaphragm means disposed in said second diaphragm means and having attached thereto said valve means, and a second compression spring disposed in said second vacuum chamber for biasing said second diaphragm means to a position in which said valve means closes said deceleration mixture circuit, said first diaphragm means being moved against the force of said first compression spring to a position in which said valve element opens said valve opening to interconnect said first vacuum chamber with said second vacuum chamber when said intake manifold vacuum reaches a predetermined value, whereby said second diaphragm means is moved against the force of said second compression spring to a position to cause said valve means to open said deceleration mixture circuit.

Claim 9

An auxiliary fuel supply system for use with a multi carburetor of the variable area venturi type for an internal combustion engine having an air cleaner, a float chamber, a carburetor induction passage leading from said air cleaner into intake manifolds of said engine, a throttle valve disposed in said carburetor induction passage and adapted to be fully closed during idling and decelerating operations of said engine, a variable area venturi formed in said carburetor induction passage upstream of said throttle valve and consisting of a constriction and an air flow control assembly to continuously reduce the effective sectional area at the venturi as said throttle valve closes, and a balancE tube connected between said intake manifolds of said engine and communicating with said carburetor induction passage downstream of said throttle valve, said auxiliary fuel supply system comprising a body, a fuel supply chamber formed in said body and communicating with said float chamber, an air chamber communicating with said air cleaner, a main mixture passage formed in said body, a main air inlet passage provided upstream side of said main mixture passage and leading from said air chamber, a main adjust screw disposed in said main air inlet passage for controlling the flow of air flowing into said main mixture passage thereby to adjust the mixture ratio of said air-fuel mixture in said main mixture passage, said body being mounted on said balance tube at its intermediate portion to connect said main mixture passage with said intake manifolds, a slow running mixture circuit formed in said body and having a slow running port opening into said main mixture passage, said slow running mixture circuit including a slow running air bleed vented to the atmosphere and a slow running fuel jet provided in said slow running mixture circuit upstream of said slow running air bleed and communicating with said fuel supply chamber, the effective areas of said slow running air bleed and said slow running fuel jet being determined to admit air and fuel in said slow running mixture circuit in an amount to provide an air-fuel mixture of optimum mixture ratio for the idling operation of said engine, a slow running adjust screw disposed in said slow running port to adjust the amount of air-fuel mixture passing therethrough, a deceleration mixture circuit formed in said body and having a deceleration port opening into said main mixture passage, said deceleration mixture circuit including a deceleration air bleed leading from said air chamber and a deceleration fuel jet provided in said deceleration mixture circuit downstream of said deceleration air bleed, said deceleration fuel jet communicating with said fuel supply chamber through a deceleration fuel supply passage formed in said body, the effective areas of said deceleration air bleed and said deceleration fuel jet being calibrated to admit air and fuel into said deceleration mixture circuit in an amount to provide an air-fuel mixture which is combustible when mixed in said main mixture passage with said air-fuel mixture supplied from said slow running port, and a control unit associated with said deceleration mixture circuit to control the amount of air-fuel mixture supplied from said deceleration port, said control unit including a housing having formed therein first and second vacuum chambers and having wall portion intervening therebetween, an outlet passage formed in said body for interconnecting said first vacuum chamber with said main mixture passage, said wall portion of said housing having formed with a valve opening which interconnects said first and second vacuum chambers with respect to each other, a cap member attached to one end of said housing, a first diaphragm member interposed between said cap member and the one end of said housing, said cap member having a central aperture constituting atmospheric vent to a chamber formed between said first diaphragm member and the inner surface of said cap member, a first valve element attached to said first diaphragm member and extending into said valve opening, a first compression spring disposed in said first vacuum chamber for biasing said first diaphragm member to a position in which said first valve element closes said valve opening, the other end of said housing being secured to the side wall of said body, a second diaphragm member interposed between the side wall of said body and the other end of said housing, said body being formed with a cavity at the side wall thereof to form a chamber in association with said second diaphragm member, said chamber communicating with said air cleaner, a second valve element attached to said second diaphragm member and extending into said deceleration mixture circuit to open and close said deceleration port, and a second compression spring disposed in said second vacuum chamber for biasing said second diaphragm member to a position in which said second valve element closes said deceleration port, said first diaphragm member being responsive to an intake manifold vacuum in said first vacuum chamber, whereby when said intake manifold vacuum exceeds a predetermined value, said first diaphragm member is moved against the force of said first compression spring to a position to cause said first valve element to open said valve opening for thereby causing said second diaphragm member to move against the force of said second compression spring to a position in which said second valve element opens said deceleration port.

Claim 10

An auxiliary fuel supply system for use with a multi carburetor of the variable area venturi type for an internal combustion engine having an air cleaner, a float chamber, a carburetor induction passage leading from said air cleaner into intake manifolds of said engine, a throttle valve disposed in said carburetor induction passage and adapted to be fully closed during idling and decelerating operations of said engine, a variable area venturi formed in said carburetor induction passage upstream of said throttle valve and consisting of a constriction and an air flow control assembly to continuously reduce the effective sectional area at the venturi as said throttle valve closes, and a balancE tube connected between said intake manifolds of said engine and communicating with said carburetor induction passage downstream of said throttle valve, said auxiliary fuel supply system comprising a body, a fuel supply chamber formed in said body and communicating with said float chamber, an air chamber communicating with said air cleaner, a main mixture passage formed in said body, a main air inlet passage provided upstream side of said main mixture passage and leading from said air chamber, a main adjust screw disposed in said main air inlet passage for controlling the flow of air flowing into said main mixture passage thereby to adjust the mixture ratio of said air-fuel mixture in said main mixture passage, said body being mounted on said balance tube at its intermediate portion to connect said main mixture passage with said intake manifolds, a slow running mixture circuit formed in said body and having a slow running port opening into said main mixture passage, said slow running mixture circuit including a slow running air bleed vented to the atmosphere and a slow running fuel jet provided in said slow running mixture circuit upstream of said slow running air bleed and communicating with said fuel supply chamber, the effective areas of said slow running air bleed and said slow running fuel jet being determined to admit air and fuel in said slow running mixture circuit in an amount to provide an air-fuel mixture of optimum mixture ratio for the idling operation of said engine, a slow running adjust screw disposed in said slow running port to adjust the amount of air-fuel mixture passing therethrough, a deceleration mixture circuit formed in said body and having a deceleration port opening into said main mixture passage, said deceleration mixture circuit including a deceleration air bleed leading from said air chamber and a deceleration fuel jet provided in said deceleration mixture circuit downstream of said deceleration air bleed, said deceleration fuel jet communicating with said fuel supply chamber through a deceleration fuel supply passage formed in said body, the effective areas of said deceleration air bleed and said deceleration fuel jet being calibrated to admit air and fuel into said deceleration mixture circuit in an amount to provide an air-fuel mixture which is combustible when mixed in said main mixture passage with said air-fuel mixture supplied from said slow running port, and a control unit associated with said deceleration mixture circuit to control the amount of air-fuel mixture supplied from said deceleration port, said control unit including a housing having formed therein first and second vacuum chambers and having wall portion intervening therebetween, an outlet passage formed in said body for interconnecting said first vacuum chamber with said main mixture passage, said wall portion of said housing having formed with a valve opening which interconnects said first and second vacuum chambers with respect to each other, a cap member attached to one end of said housing, a first diaphragm member interposed between said cap member and the one end of said housing, said cap member having a central aperture constituting atmospheric vent to a chamber formed between said first diaphragm member and the inner surface of said cap member, a first valve element attached to said first diaphragm member and extending into said valve opening, a first compression spring disposed in said first vacuum chamber for biasing said first diaphragm member to a position in which said first valve element closes said valve opening, the other end of said housing being secured to the side wall of said body, a second diaphragm member interposed between the side wall of said body and the other end of said housing, said body being formed with a cavity at the side wall thereof to form a chamber in association with said second diaphragm member, said chamber communicating with said air cleaner, a second valve element attached to said second diaphragm member and extending into said deceleration mixture circuit to open and close said deceleration port, and a second compression spring disposed in said second vacuum chamber for biasing said second diaphragm member to a position in which said second valve element closes said deceleration port, said first diaphragm member being responsive to an intake manifold vacuum in said first vacuum chamber, whereby when said intake manifold vacuum exceeds a predetermined value, said first diaphragm member is moved against the force of said first compression spring to a position to cause said first valve element to open said valve opening for thereby causing said second diaphragm member to move against the force of said second compression spring to a position in which said second valve element opens said deceleration port.