Duel fuel system for internal combustion engine

Claim 2

A dual fuel system for an internal combustion engine comprising: primary fuel-air mixing means to produce a primary fuel-air mixture of a primary fuel and air; auxiliary fuel-air mixing means to produce an auxiliary fuel-air mixture of an auxiliary fuel and air; manually operable control means to control passage of the primary mixture to an intake manifold; a vacuum source coupled to and influenced by said control means; auxiliary fuel flow control means coupled to said auxiliary fuel-air mixing means and to said vacuum source for enabling increased auxiliary fuel-air mixture flow to said manifold in response to increasing vacuum above 3"Hg at said vacuum source and for decreasing auxiliary fuel-air mixture flow to said manifold in response to decreasing vacuum above 3"Hg at said vacuum source but maintaining auxiliary fuel-air mixture flow to said manifold notwithstanding source vacuum less than 3"Hg.

Claim 3

The system of claim 1 wherein: said auxiliary fuel-air mixing means are a carburetor having a fuel-air mixture outlet means; said auxiliary fuel flow control means include a throttle valve in said outlet means and a vacuum controller coupled to said throttle valve and to said vacuum source.

Claim 4

The system of claim 2 wherein: said vacuum source is a modified manifold vacuum source and includes a distributor vacuum port in a gasoline-air mixing carburetor and is responsive to engine idle condition to provide a vacuum not exceeding 3"Hg.

Claim 5

A dual fuel system for an internal combustion engine comprising: primary fuel-air mixing means to produce a mixture of air and a primary fuel; auxiliary fuel-air mixing means to produce a mixture of air and an auxiliary fuel; manual throttle control means associated with said primary mixing means to control flow of primary fuel-air mixture to said engine; auxiliary fuel flow control means coupled to said auxiliary mixing means and to said manual throttle control means for reducing auxiliary fuel-air mixture flow in response to movement of said manual throttle control means from partial open position and in a direction calling for more power from the engine; said primary fuel-air mixing means including a gasoline-air mixing carburetor; said auxiliary fuel-air mixing means including a second carburetor having a fuel-air mixture outlet means; said auxiliary fuel flow control means including a throttle valve in said outlet means and a vacuum controller coupled to said throttle valve and to a modified manifold vacuum source; said modified manifold vacuum source including a throttle influenced vacuum source in said gasoline-air mixing carburetor and producing vacuum of 3"Hg or less at normal engine idle; said gasoline-air mixing carburetor having fuel-air mixture outlet means, with a throttle valve therein; the system further comprising an internal combustion engine intake manifold means; said fuel-air mixture outlet means of said carburetors being connected to said intake manifold means independently of each other, with the said throttle valves of said carburetors controlling admission of fuel-air mixtures therefrom directly to said manifold means exclusive of control thereof by any further throttle valve.

Claim 6

A dual fuel system for an internal combustion engine comprising: primary fuel-air mixing means to produce a mixture of air and a primary fuel; auxiliary fuel-air mixing means to produce a mixture of air and an auxiliary fuel; manual throttle control means associated with said primary mixing means to control flow of primary fuel-air mixture to said engine; auxiliary fuel flow control means coupled to said auxiliary mixing means and to said manual throttle control means for reducing auxiliary fuel-air mixture flow in response to movement of said manual throttle control means from partial open position and in a direction calling for more power from the engine; said primary fuel-air mixing means including a gasoline-air mixing carburetor; said auxiliary fuel-air mixing means including a second carburetor having a fuel-air mixture outlet means; said auxiliary fuel flow control means including a throttle valve in said outlet means and a vacuum controller coupled to said throttle valve and to a modified manifold vacuum source; said modified manifold vacuum source including a throttle influenced vacuum source in said gasoline-air mixing carburetor and producing vacuum of 3"Hg or less at normal engine idle; said gasoline-air mixing carburetor having fuel-air mixture outlet means, with a throttle valve therein; the system further comprising an internal combustion engine intake manifold means; said fuel-air mixture outlet means of said carburetors being connected to said intake manifold means independently of each other, with the said throttle valves of said carburetors controlling admission of fuel-air mixtures therefrom directly to said manifold means exclusive of control thereof by any further throttle valve.

Claim 7

In an internal combustion engine fueled by a gasoline-air mixture from a primary carburetor to an intake manifold, with a first throttle valve manually operable between closed throttle and open throttle conditions for controlling admission of the gasoline-air mixture to the intake manifold, the improvement comprising: auxiliary carburetor means mixing alcohol and air, said auxiliary carburetor means having mixture outlet means communicating with said intake manifold through a passageway bypassing said first throttle valve, said passageway having therein a second throttle valve controlling admission of an alcohol-air mixture to the intake manifold.

Claim 8

In an internal combustion engine fueled by a gasoline-air mixture from a primary carburetor to an intake manifold, with a first throttle valve manually operable between closed throttle and open throttle conditions for controlling admission of the gasoline-air mixture to the intake manifold, the improvement comprising: auxiliary carburetor means mixing alcohol and air, said auxiliary carburetor means having mixture outlet means communicating with said intake manifold through a passageway bypassing said first throttle valve, said passageway having therein a second throttle valve controlling admission of an alcohol-air mixture to the intake manifold.

Claim 9

The improvement of claim 5 and further comprising: auxiliary throttle control means including a vacuum-mechanical unit having an operating member coupled to said second throttle valve and having a vacuum operator connected to a vacuum source, said unit being responsive to increasing vacuum at said source to increase the opening of said second throttle valve, said second throttle valve having an idle position wherein said auxiliary carburetor is enabled to supply an alcohol-air mixture to said intake manifold.

Claim 10

The improvement of claim 6 and further comprising: auxiliary throttle return means associated with said second throttle valve and urging said second throttle valve toward closed condition.

Claim 11

The improvement of claim 7 wherein: said second throttle valve is operable from said idle position toward a wide-open position, said return means being inoperable on said second throttle valve during initial operation from said idle position toward wide-open position.

Claim 12

The improvement of claim 8 wherein: said vacuum-mechanical unit is operable to move said second throttle valve from idle position at source vacuum less than 3"Hg to wide-open position in response to source vacuum in excess of 7"Hg.

Claim 13

The system of claim 2 wherein: said vacuum source is a modified manifold vacuum source responsive to engine idle condition to provide a vacuum not exceeding 3"Hg.

Claim 14

The improvement of claim 6 wherein: said vacuum-mechanical unit is operable to maintain, at some source vacuum in excess of 7"Hg, the maximum open position of which said second throttle valve is capable.

Claim 15

The improvement of claim 6 wherein: said vacuum-mechanical unit is operable, in response to a maximum source vacuum greater than source vacuum at engine idle, to move said second throttle valve from said idle position to a position enabling the maximum alcohol-air mixture flow to said intake manifold.

Claim 16

In an internal combustion engine fueled by a mixture of a primary fuel and air from a primary carburetor to an intake manifold, with a first throttle valve manually operable between closed throttle and open throttle conditions for controlling admission of the primary fuel-air mixture to the intake manifold, the improvement comprising: auxiliary carburetor means mixing an auxiliary fuel and air, said auxiliary carburetor means having mixture outlet means communicating with said intake manifold through a passageway bypassing said first throttle valve, said passageway having therein a second throttle valve controlling admission of an auxiliary fuel-air mixture to the intake manifold; auxiliary throttle control means including a vacuum-mechanical unit having an operating member coupled to said second throttle valve and having a vacuum operator connected to a vacuum source, said unit being responsive to increased vacuum at said source to increase the opening of said second throttle valve, said second throttle valve having an idle position wherein said auxiliary carburetor is enabled to supply an auxiliary fuel-air mixture to said intake manifold; auxiliary throttle return means associated with said second throttle valve and urging said second throttle valve toward closed condition; said second throttle valve being operable from said idle position toward a wide-open position, said return means being inoperable on said second throttle valve during initial operation from said idle position toward wide-open position.

Claim 17

In an internal combustion engine fueled by a mixture of a primary fuel and air from a primary carburetor to an intake manifold, with a first throttle valve manually operable between closed throttle and open throttle conditions for controlling admission of the primary fuel-air mixture to the intake manifold, the improvement comprising: auxiliary carburetor means mixing an auxiliary fuel and air, said auxiliary carburetor means having mixture outlet means communicating with said intake manifold through a passageway bypassing said first throttle valve, said passageway having therein a second throttle valve controlling admission of an auxiliary fuel-air mixture to the intake manifold; auxiliary throttle control means including a vacuum-mechanical unit having an operating member coupled to said second throttle valve and having a vacuum operator connected to a vacuum source, said unit being responsive to increased vacuum at said source to increase the opening of said second throttle valve, said second throttle valve having an idle position wherein said auxiliary carburetor is enabled to supply an auxiliary fuel-air mixture to said intake manifold; auxiliary throttle return means associated with said second throttle valve and urging said second throttle valve toward closed condition; said second throttle valve being operable from said idle position toward a wide-open position, said return means being inoperable on said second throttle valve during initial operation from said idle position toward wide-open position.