This invention relates to impellers and agitors used to mix industrial slurries and also used to propel marine vessels. More particularly this invention relates to an impeller having a unique design which facilitates greater linear movement of a media with less torque; and which accordingly, consumes less power, to perform equivalent work.
The applicant is a mechanical designer who has worked and experimented with impellers used in mixing. He has extensively varied impeller parameters which are commonly accepted in hopes of producing a more efficient impeller. Many of the variations which he has produced have an empirical appeal as sensible, but none the less, these variations are radical in industries which have been relatively static in impeller designs for long periods.
Efficiency and energy conservation today more than ever are principal concerns, and almost the only concern in the design of impellers for use in any media.
One accepted measure of an impeller""s efficiency is the ratio of the flow produced by the impeller divided torqe. A minute variation in an impeller""s efficiency on a marine vessel translates into not only thousands of dollars of fuel saved on a single trans-Atlantic voyage, but additionally, more capacity to carry cargo, less wear on the power plant, and reduced maintenance costs. Operational profitability is hugely impacted. The variation of a design parameter which produces a minute improvement in the efficiency of an impeller is highly significant.
It is an object of this invention to disclose multiple variations in the design of an impeller which individually result in a more efficient impeller. In combination, these variations result in a substantially more efficient impeller. It is an object of this invention to disclose an impeller which has substantially varying slopes which increase from the leading, to the trailing edge of the impeller, and which facilitate a gradual acceleration of the media when the impeller rotates. It is an object of this invention to disclose an impeller which is designed to efficiently penetrate the media as it rotates. The peripheral portion of the spiralled leading edge of the impeller comprises a bulbuous tip which is the first portion of the blade to penetrate the media. This bulbuous tip is fashioned after a bulbuous bow on a ship. It is yet a further object of this invention to disclose an impeller design which is shaped to inwardly accelerate the media as it rotates therein. A blade portion of the impeller increases in slope from its inner to its peripheral edge. The impeller effectively draws the media to its central portion wherein the media is trapped and accelerated parallel to the axis of the impeller. The resulting wake produced by an operating impeller is generally more axially directed than an impeller of conventional design which throws the media more outwardly and whose wake tends to be more outwardly directed. It is a final object of this invention to disclose an impeller having a leading edge which spirals back from the extended bulbuous tip to the central hub thereof.
In an impeller for rotation in a media of the type having a central hub, an inclined blade portion having an inner radial edge portion attached to the central hub, an intermediate blade portion adjoined to the inner radial edge portion on one side, a peripheral edge portion attached to and extending outwardly from the central portion, a leading edge portion, a trailing edge portion, a front face, and a rear face, one aspect of this invention provides for an impeller having the following improvement. The blade portion has a front media-accelerating face and substantially varying slopes which increase from the leading to the trailing edge portions of the media-accelerating front face of the impeller, to facilitate a gradual acceleration of the media as the impeller rotates. The slope of front media-accelerating face of the blade portion also gradually increases moving outwardly along the intermediate blade portion, then to and along the peripheral edge portion thereof. The blade portions have increasing slope to accelerate the media more axially, and less radially, as the impeller rotates.
In a preferred aspect of the invention blade portion has leading and trailing edge portions which each have an elongated forwardly extended peripheral portion. The forwardly extending peripheral portions culminate in a tip portion which is preferably bulbuous, to facilitate efficient penetration of the media by the blade portion.