Vacuum controlled variable pressure fuel regulator and carburetor

In combination with an internal combustion engine having a carburetor with a needle valve and a float chamber, a fuel pump operable to deliver fuel to the carburetor through the needle valve, a regulator to reduce the fuel pressure at the needle valve at least during substantial portions of an engine's normal operating cycle, an engine intake manifold for passing fuel and air to the combustion chambers of the engine and located downstream from the carburetor and means pressure communicating the manifold with the regulator, an improvement in the regulator comprising:

• (a) a housing having first and second cavities;
• (b) a first diaphragm in the housing having opposite sides bounding the first and second cavities;
• (c) passage means for fuel into the first cavity;
• (d) passage means for fuel from the first cavity;
• (e) valve means in the passage means into the first cavity for the control of the volume of fuel flowing into the first cavity and consequently the pressure there, the valve means being upstream of the first cavity and being coupled to the first diaphragm for movement with the first diaphragm to tend to open or to close the passage into the first cavity with the tendency to close being in response to increasing fuel pressure in the first cavity;
• (f) first biasing means acting on the first diaphragm in opposition to fuel pressure in the first cavity to tend to open the valve means, the biasing means maintaining the valve element at a predetermined open position corresponding to a low fuel pressure to the needle valve and a normal operating fuel pressure in the first cavity;
• (g) second diaphragm means in the housing;
• (h) means in the housing to subject one side of the second diaphragm to engine manifold pressure such that the second diaphragm moves in response to changes in such pressure;
• (i) means coupling the first diaphragm and the second diaphragm together only at and above a predetermined high absolute engine manifold pressure to open the valve means beyond the predetermined open position and increase the fuel pressure acting on the needle valve in proporation to increases in absolute manifold pressure above the predetermined high absolute engine manifold pressure;
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• (j) second biasing means acting on the second diaphragm to urge it into a fixed position.

In combination with an automotive fuel pump having a fuel discharge opening from which fuel is discharged at a first pressure and a carburetor having a fuel inlet and a float actuated needle valve that regualtes the height of fuel in the bowl of said carburetor in accordance with the magnitude of the pressure of said fuel delivered to said fuel inlet, a device actuated by the degree of vacuum in a manifold of the engine which is supplied by fuel and air from said carburetor to reduce the pressure of said fuel from said first pressure to a second lesser pressure when said engine is being started, accelerated or under a substantial load, and to a third pressure less than said second pressure when said engine is idling or at a cruising speed, said device including:

• (a) a first hollow body that has a fuel inlet in communication with said fuel discharge opening of said fuel pump;
• (b) a first resilient diaphragm transversely disposed in said first hollow body and that subdivides the interior thereof into first and second cavities, said second cavity vented to the atmosphere;
• (c) a valve seat within said housing intermediately disposed between said inlet and said first cavity;
• (d) a valve member that depends from said first diaphragm through said valve seat, said valve member including a flat valve surface substantially parallel to said first diaphragm and an upwardly and inwardly tapering side surface adjacent said flat surface that extends towards said first diaphragm, with a portion of said tapered side surface adjacent said flat valve surface of greater diameter than said valve seat, said tapered side surface and said valve seat cooperating to define an annulus space that varies in width as said first diaphragm flexes upwardly and downwardly;
• (e) first conduit means that connect said fuel inlet of said carburetor to a discharge opening in said housing in communication with said first cavity;
• (f) a stop on said first diaphragm that limits the movement of the latter towards said valve seat to provide a maximum width for said annulus space;
• (g) first spring means that urge said valve member towards said valve seat;
• (h) second spring means of greater strength than said first spring means that urge said valve member away from said valve seat;
• (i) a plunger slidably mounted in said housing and axially aligned with said valve member, said plunger having first and second ends, said first end capable of contacting said first diaphragm;
• (j) a second circular resilient diaphragm that has said second end of said plunger secured thereto;
• (k) a second hollow body secured to said first hollow body and with the peripheral portion of said second resilient diaphragm gripped therebetween, said second hollow body and said second diaphragm cooperating to define a confined space therebetween;
• (l) third spring means that at all times tend to maintain a sufficient force on said second diaphragm and plunger so as to maintain said first diaphragm and valve member in a position where said annulus space is of maximum width and said fuel is delivered to said carburetor at said second pressure;
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• (m) second conduit means that connect said confined space to said manifold so that the magnitude of vacuum increase as said engine idles or operates at cruising speed occurs in said confined space to deform said second resilient diaphragm upwardly to overcome the force of said third spring means and to separate said plunger from said first diaphragm, the pressure of said fuel in said first cavity and the force of said first spring means overcoming the force of said second spring means after said plunger separates from said first diaphragm to deform said first diaphragm upwardly to lessen the width of said annulus space and reduce the pressure of fuel delivered to said carbuetor from said second pressure to said third pressure, but upon said engine being accelerated or subjected to a substantial load, the vacuum in said manifold and confined space decreases and allows said third spring means to deform said second diaphragm downwardly to force said plunger into contact with first diaphragm and return said valve member to a position where it provides an annulus space of maximum width with said valve seat to permit said fuel to be delivered to said carburetor at said second pressure.