Gas separation – With guide means effecting removal of constituent layer out... – At escape means for heavier constituent
Reexamination Certificate
1999-03-19
2001-08-28
Smith, Duane S. (Department: 1724)
Gas separation
With guide means effecting removal of constituent layer out...
At escape means for heavier constituent
C055S401000, C055S403000, C055S406000, C055S456000
Reexamination Certificate
active
06280493
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention pertains to air pre-cleaners. More particularly, this invention relates to an air pre-cleaner employing an inlet vane assembly and a rotating impeller assembly.
Air pre-cleaners are used for removing particulates from the air prior to introducing the air through an air cleaner or filter, which is connected to a carburetor or air intake structure, of an internal combustion engine. Pre-cleaners are generally located on the open inlet side of the air intake pipes or stacks of an internal combustion engine. The function of the pre-cleaner is to remove as many contaminates from the air as possible before the air flows into an air filter medium upstream from the internal combustion engine.
Air pre-cleaners operate on the principle of centrifugal separation. Outside air, with its entrained contaminates, enters the pre-cleaner from the vacuum created by the engine. The air and contaminates traverse a set of fixed, static vanes which cause the air to circulate at a great speed. Centrifugal force throws the contaminates and moisture towards the outer wall of the pre-cleaner. The contaminates follow the wall until the reach an opening where they are discharged back into the atmosphere or collected. Clean, dry air is then allowed to the enter the filter and subsequently, the internal combustion engine.
As pre-cleaners work on centrifugal separation, greater air flow velocity will result in better separation between the air and the contaminates. The best contaminate separation happens when the engine in running at a high speed (in r.p.m.) thus causing a high velocity for the air which is flowing into the pre-cleaner. As the velocity of air flow decreases, the centrifugal force on the contaminates also decreases reducing the separation efficiency of the pre-cleaner.
Undesirable contaminates in the atmosphere include particulate matter such as dirt, dust, sand, snow and the like. While most engines include air filters which are meant to remove such contaminates from the air that feeds the engine, engine pre-cleaners are also beneficial in order to extend the life of the air filter and extend the engine's life while at the same time improving fuel economy.
Several different designs of air pre-cleaners are commercially available in the marketplace. In one design, an air pre-cleaner uses a rotatable impeller or spinner to separate particles from air, discharge the dirty air and particle mixture circumferentially from a housing and direct the clean air to the air intake structure of an engine. The clean air moves centrally through a stack to the engine in response to a vacuum pressure on the air moving towards the engine. This air pre-cleaner has an air inlet vane assembly located in the bottom of the housing. The air flows upwardly in a circular path into a centrifugal separation chamber and then turns downwardly into the centrally located clean air exit opening. This impeller is used to pump air and articulate matter out through side discharge openings. This type of air pre-cleaner, however, does not urge the air flowing over the vanes of the pre-cleaner toward the outer walls of the separation chamber in order to enhance particle separation from the air.
Known air pre-cleaners have also included a design in which air flows into the top of the air pre-cleaner and flows axially downwardly through the pre-cleaner and into the intake stack of the engine. Although such pre-cleaners may perform adequately with respect to particulate material, this accomplished sometimes at the expense of reduced air flow. In other words, the pre-cleaner itself may become an air restriction. The known pre-cleaners of this type do not use static vanes which cause the air to circulate at as a great a velocity as such vanes could. Also, some pre-cleaners are only useable when positioned in one orientation, i.e., positioned on a vertical axis or positioned on a horizontal axis. Moreover, the known pre-cleaners do not have an optimized impeller construction. Also, they do not have stator vanes in the clean air exhaust passage of the pre-cleaner.
Accordingly, it has been considered desirable to develop a new and improved air-pre-cleaner which would overcome the foregoing difficulties and others while providing better and more advantageous overall results.
BRIEF SUMMARY OF THE INVENTION
An air pre-cleaner for centrifugally ejecting heavier than air particulates from an air stream for use in an apparatus having an air intake is provided.
More particularly, the air pre-cleaner comprises a hood having an opening in which air enters the pre-cleaner and a vane assembly including a centrally positioned dome, a collar encircling the dome and a plurality of vanes, each vane being connected at an inner end to the dome and at an outer end to the collar. Each vane is angled in relation to a horizontal plane. The vanes are inclined slightly away from the direction of air movement in the plane perpendicular to forward motion of the entering air. An impeller assembly in rotatably mounted to the vane assembly. Also provided is a base to which the vane assembly and the hood are secured. The base includes a clean air exit port.
In accordance with another aspect of the present invention, an apparatus is provided for separating particles from a gas carrying the particles.
More particularly in accordance with this aspect of the invention, the apparatus comprises a housing including a separation chamber, the housing having an inside wall surface surrounding the chamber. The housing comprises an inlet opening through which air enters the pre-cleaner and a vane assembly including a centrally positioned dome, a collar encircling the dome and a plurality of vanes, each connected at a radially inner edge to the dome and at a radially outer edge to the collar. An impeller assembly is rotatably mounted in the separation chamber. The impeller assembly includes at least one vane. Said at least one vane includes a first section positioned in a first plane and a second section which is mounted at an obtuse angle in relation to the first section.
Once advantage of the present invention is the provision of a new and improved air pre-cleaner.
Another advantage of the present invention is the provision of an air pre-cleaner having a vane assembly which includes a set of static vanes having a fully concave surface along which inlet air flows causing the air to rotate at a great centrifugal speed in relation to forward motion. In one embodiment, the vane pitch is twisted to keep the chord width relatively constant over the full vane length. This causes an essentially constant velocity over the entire vane surface. In another embodiment, the vane chord is slightly wider at the inner diameter than at the outer diameter.
Still another advantage of the present invention is the provision of an air pre-cleaner having a vane assembly in which the vanes are inclined slightly away from the direction of air movement in the plane perpendicular to forward motion of the entering air. For best particle separation, it has been found that air must be forced toward the outer walls of the separation chamber.
Yet another advantage of the present invention is the provision of an air pre-cleaner having an impeller with a shape that will not unload with increasing static pressure. To this end, the outer blade of the impeller has a compound shape. The shape is such that neither of the two impeller blade surfaces will unload or cavitate at increasing static pressures.
Still yet another advantage of the present invention is the provision of an air pre-cleaner having an impeller which makes less noise when spinning than do conventional impeller designs.
Yet still another advantage of the present invention is the provision of an air pre-cleaner which includes a impeller with ejection blades that cooperate with stator vanes in the housing of the air pre-cleaner to provide much higher ejection pressures than can be obtained with the known designs. The design provides more air flow for a given size pre-cleaner than is true of the known air p
Dreison International, Inc.
Fay, Sharpe, Fagan, Minnch & McKee, LLP
Smith Duane S.
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