Metal founding – Process – Shaping liquid metal against a forming surface
Reexamination Certificate
1999-12-23
2001-10-23
Chiesa, Richard L. (Department: 1724)
Metal founding
Process
Shaping liquid metal against a forming surface
C029S526400, C029S527600, C164S069100, C164S477000, C164S132000, C261S023200, C261SDIG001, C261SDIG003
Reexamination Certificate
active
06305461
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to internal combustion engines and more particularly to carburetors for internal combustion engines.
While the present invention discusses the use of a “four-barrel” or four venturis within a carburetor, the invention is not so limited as those of ordinary skill in the art will readily appreciate.
The venturi within a carburetor is shaped to form streamlined air inlets that rapidly accelerate the air through the narrow venturi throat section. Air traveling fast experiences a large pressure drop, thereby creating a venturi vacuum. The higher the air flow going into the venturi, the larger the venturi suction.
Leaving the low pressure/high air velocity venturi throat, the air exits through a gently widening taper which reduces the air velocity to create a higher pressure zone.
A booster amplifies the suction signal of the main venturi found in the carburetor. This allows the fuel to be drawn more efficiently. Fuel and a small amount of air come up from the main well in the metering block to deliver a rich air emulsion from a center nozzle. It exits, like a froth of fuels, and leaves the booster surrounded by the venturi air, with which it mixes en route to the cylinders of the internal combustion engine.
It is clear that the efficiency of the booster directly affects the efficiency of the carburetor and hence the engine. The existing art for the manufacture of boosters does not take into account the affect that otherwise minor flaws can have on the overall affect.
It is clear that there is a need for a more durable and efficient drop leg booster for the creation of efficient assemblies.
SUMMARY OF THE INVENTION
This invention provides a booster equipped carburetor in which the venturi bores in the carburetor have an enhanced drop leg booster. The carburetor is generally a traditional carburetor; the drop leg booster of this invention provides enhanced fuel flow into the venturi bores of the carburetor.
The “drop legs” aspect of the present invention positions the booster's own venturi mechanism at the proper point within the venturi bore of the carburetor. In this context, the “drop leg” serves as both the conduit for the fuel and also as the support mechanism for the booster's venturi.
While some embodiments of the invention utilize two supporting “legs”, the preferred embodiment of the invention employs a single “leg”, thereby providing as little air flow disruption to the air-flow through the carburetor's venturi bore as possible.
The carburetor portion of the assembly uses at least one venturi bore (other embodiments use a dual bore carburetor). In the preferred embodiment, four venturi bores are employed by the carburetor. These venturi bores (together with the boosters) are used to create the desired fuel/air ratios for proper operation of the internal combustion engine.
In this context, the booster provides a consistent flow of fuel into a first venturi found on the booster itself.
Communication of the fuel to the booster's own venturi is accomplished through the use of a “bent” channel member. The channel member is secured to a fuel source (located in a wall of the carburetor or the venturi bore of the carburetor) at one end. This fuel flows in a “downward” direction to the booster's own venturi.
The channel member communicates fuel to the venturi orifice and positions the venturi orifice below the second end of said channel member within said venturi bore of said carburetor. The length and the angle of the channel member's “drop” is dictated by the carburetor's own design. Those of ordinary skill in the art appreciate how the position of the booster's venturi within the venturi bore of the carburetor affects the overall performance.
The performance of the booster is significantly improved by the method of manufacture of the booster itself. Within the invention's method of manufacture, the interior of the channel member has smooth sides to assure consistent flow without undue turbulence. Eddies created by an un-smooth or stepped channel walls are avoided. The smooth wall nature of the invention's channel assure that a consistent fuel flow is assured and that changes in flow rates do not create unexpected results or performance from the booster.
Another advantage that the present invention creates is the elimination of a “stress riser” at the intersection of the two legs. This provides for a more durable and stable leg arrangement which is less likely to break during use.
In this context, the booster is manufactured using die casting techniques. Die casting is a metal casting process in which molten metal is forced under pressure into a mold. Typically the two types of die cast methods are hot-chamber and cold-chamber.
The die for the booster blank is also equipped with a channel insert (core pin) which extends through the primary drop leg section and partially into the secondary portion of the drop leg. The insert is shaped to mate with a drill bit (performed after the blank has hardened and been removed from the die) which is used to create the segment extending from the lower portion of the necking of the booster's venturi through the secondary portion of the drop leg.
In this manner, a channel is created which extends from the fuel source, through the primary leg (both created during the casting operation), through the secondary leg (drilled after the casting), to the booster venturi. Since the die cast channel is shaped to mate with the drilled channel smoothly, eddies and turbulence are minimized, providing for a consistent operation by the booster.
The invention, together with various embodiments thereof, will be more fully explained by the accompanying drawings and the following descriptions thereof.
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Birdwell Janke & Durando, PLC
Chiesa Richard L.
POW Engineering, Inc.
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