Patent Application
20100170479
1. Field of the Invention
The present invention is related to a mechanical fuel pump driven by, and incorporated within, a dynamic balancing mechanism in an internal combustion engine.
2. Disclosure Information
Automotive internal combustion engines once used carburetors for mixing air with fuel. Because carburetors utilize venturis to draw fuel into the air, carburetors were typically fed by low pressure fuel sources, such as mechanically or vacuum driven diaphragm pumps.
With the advent of electronic fuel injection, the ubiquitous solution for fuel pumps became the in-tank mounted electric pump. Such pumps are typically capable of reliably producing fuel pressures in the sub-100 p.s.i. regime.
Because of increasingly more stringent vehicle emission controls, engine developers have turned to direct injection of gasoline into the combustion chambers of the newest engines. Unfortunately, better mixture preparation requires that the desired injection pressures be much higher, and with these new fuel systems, electric pumps will likely be relegated to the role of a lift pump providing fuel to a higher pressure pump driven by the engine. Of course, it is desirable to provide such an added pump without unnecessary expense, and with a minimal requirement for additional space. Although it is known to mount pumps externally upon an engine, ever more crowded engine compartments do not readily lend themselves to this solution.
It would be desirable to provide an engine-driven mechanical fuel pump which has a minimum number of additional parts, coupled with high pressure capability, and which causes no added expenditure of precious space within the underhood environment of the vehicle.
A fuel pump for an internal combustion engine includes a housing containing both a balancer and a fuel pump, with the fuel pump including a working chamber contained within the housing. A fuel pump also includes at least one balance shaft mounted within the housing, with the balance shaft having at least one eccentric lobe for actuating a follower connected with a pump plunger mounted reciprocably within the working chamber. According to another aspect of the present invention, the balance shaft is driven rotationally by a crankshaft, preferably at twice the rotational speed of the crankshaft.
According to another aspect of the present invention, the fuel pump further includes at least one pressure control valve operatively connected with the working chamber and mounted within the housing, as well as a pulsation damper operatively connected within the working chamber and also mounted within the housing.
According to another aspect of the present invention, the housing of the fuel pump and balancer may be mounted adjacent a crankshaft of an engine.
According to another aspect of the present invention, the pumping element driven by the balance shaft may comprise in the alternative, a reciprocating pump, or a rotary pumping element such as a gerotor element, or a set of intermeshing gears.
It is an advantage of a combination dynamic balancer and fuel pump according to the present invention that the number of added parts needed to provide high pressure fuel pumping capability within an engine is reduced, as compared with prior art pumps, many of which are merely bolted to the outside of the engine in some fashion or another.
It is another advantage according to the present invention that the present fuel pump and balancer combination requires little, if any, additional space within the engine compartment of the vehicle.
It is another advantage of a combination balancer and high pressure fuel pump according to the present invention that very high fuel discharge pressures may be produced reliably due to the inherent strength of the integral working chamber and balancer housing.
Other advantages, as well as features of the present invention, will become apparent to the reader of this specification.
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The fuel pump of
The foregoing invention has been described in accordance with the relevant legal standards, thus the description is exemplary rather than limiting in nature. Variations and modifications to the disclosed embodiment may become apparent to those skilled in the art and fall within the scope of the invention. Accordingly the scope of legal protection afforded this invention can only be determined by studying the following claims.
