US20030231959A1 - Impeller assembly for centrifugal pumps - Google Patents

Abstract

An impeller assembly for centrifugal pumps that enables self-priming in a relatively short time period includes an impeller and at least one winglet (e.g., six winglets with a trapezium cross-sectional shape). The impeller includes an impeller body with an eye opening therein. The eye opening is configured for the passage of a fluid (e.g., water) therethrough when the impeller assembly is in use. The impeller body also includes at least one vane, with a leading end, disposed about the eye opening. The at least one winglet is positioned to protrude into the eye opening of the impeller body and may, for example, be coupled to the leading end of the vane.

Description

BACKGROUND OF THE INVENTION
• 1. Field of the Invention [0001]
• The present invention relates, in general, to pump assemblies and, in particular, to impeller assemblies for centrifugal pumps. [0002]
• 2. Description of the Related Art [0003]
• Centrifugal pumps are widely used in chemical, food, irrigation and other industries to pump a variety of liquids (e.g., water) and liquid-solid mixtures. Centrifugal pumps are a type of kinetic energy pump that imparts energy to a liquid through centrifugal force produced by a rotating impeller. The energy is used to increase the pressure of the liquid and move the liquid from one point to another. [0004]
• FIG. 1 is a simplified cross-sectional depiction of a conventional [0005] centrifugal pump 10 that includes a stationary casing 12 and an impeller 14 with curved vanes 16 (also referred to as “blades” and shown as lines for simplicity) and an axially-disposed eye opening 18. Rotation of impeller 14, and thus curved vanes 16, (e.g., by a motor [not shown] operatively coupled to impeller 14) within stationary casing 12 reduces the pressure at eye opening 18 of the impeller, causing liquid to flow into eye opening 18 from a suction inlet (e.g., an intake pipe, not shown).
• Curved [0006] vanes 16 are configured to accelerate and direct the liquid away from eye opening 18. Rotating curved vanes 16 of impeller 14 direct the liquid outward by centrifugal force, into stationary casing 12 and subsequently out a discharge exit 20. The accelerated outward flow of the liquid (i.e., from eye opening 18 towards stationary casing 12) reduces the pressure at eye opening 18, allowing more liquid to enter eye opening 18.
• A drawback of centrifugal pumps is that they must be “primed” prior to use. “Priming” is the addition of liquid to the casing in order to displace (i.e., evacuate) any entrained air, create a liquid seal within the casing and, thereby, prepare the pump for the initiation of liquid flow therethrough. Although self-priming centrifugal pumps (i.e., a centrifugal pump that is configured to automatically remove [evacuate] air from the suction inlet and that may handle liquids, gases and liquid-gas mixtures) are known, the time period required to complete a self-priming process in such self-priming centrifugal pumps may be undesirably long. [0007]
• Still needed in the field, therefore, is a self-priming centrifugal pump that may complete a self-priming process in a relatively short time period. In addition, the self-priming centrifugal pump should be or a relatively simple and easily manufactured structure. [0008]
BRIEF SUMMARY OF THE INVENTION
• The present invention provides an impeller assembly for centrifugal pumps that enables self-priming in a relatively short time period. In addition, the impeller assembly is of a relatively simple and thus easily manufactured construction. [0009]
• An impeller assembly for a centrifugal pump according to one exemplary embodiment of the present invention includes an impeller and at least one winglet. The impeller includes an impeller body with an eye opening therein. The eye opening is configured for the passage of a fluid (e.g., water) therethrough when the impeller assembly is in use. The impeller body also includes at least one vane, with a leading end, disposed about the eye opening. The winglet(s) are positioned to protrude into the eye opening of the impeller body and may, for example, be coupled to the leading end of the vane. [0010]
• The provision of winglet(s) in the eye opening of impeller assemblies according to one exemplary embodiment of the present invention has been demonstrated to significantly reduce the time period required for a self-priming process when such impeller assemblies are used in centrifugal pumps. It is postulated, without being limiting, that this reduction is due to two effects. First, when in motion during use of the impeller assembly, the winglet(s) provide an air-foil-like dynamic with the eye opening that creates a vacuum-differential (also referred to as “lift”) effect. The vacuum differential (“lift”) effect enhances the evacuation of gas (e.g., air) from the centrifugal pump during a self-priming process. Second, moving winglet(s) serve to divide any gas bubbles (e.g., air bubbles) with which they come into contact into smaller gas bubbles. The smaller gas bubbles are more readily entrained in liquid passing through the centrifugal pump and, therefore, quickly evacuated from the centrifugal pump. [0011]
• Furthermore, the inclusion of winglets in an impeller assembly according to one exemplary embodiment of the present invention results in simple and easily manufactured impeller assembly. [0012]
• A better understanding of the features and advantages of the present invention will be obtained by reference to the following detailed description that sets forth illustrative embodiments, in which the principles of the invention are utilized, and the accompanying drawings[0013]
BRIEF DESCRIPTION OF THE DRAWINGS
• FIG. 1 is a simplified cross-sectional depiction of a conventional centrifugal pump; [0014]
• FIG. 2A is a simplified cross-sectional depiction of an impeller assembly according to one exemplary embodiment of the present invention; [0015]
• FIG. 2B is a simplified cross-sectional depiction of the impeller assembly of FIG. 2A along line A-A. [0016]
• FIG. 3 is a drawing depicting the cross-sectional shape of a winglet included in one embodiment of the present invention; and [0017]
• FIGS. 4A, 4B and [0018] 4C are simplified left-side, edge and right-side depictions, respectively, of an impeller body included in one embodiment of the present invention.
DESCRIPTION OF PREFFERED EXEMPLARY EMBODIMENTS
• FIGS. 2A and 2B are simplified depictions of an [0019] impeller assembly 100 for use in a centrifugal pump in accordance with one exemplary embodiment of the present invention. Impeller assembly 100 includes an impeller 102 and six winglets 104 (shown in cross-section in FIG. 3). Impeller 102 includes a first impeller body 106 with an eye opening 108 therein, a second impeller body 110 (through which eye opening 108 also passes) and a keyway 112. Eye opening 108 is configured for the passage of fluid (e.g., water) therethrough when impeller assembly 100 is in use in a centrifugal pump.
• [0020] Winglets 104 are configured to protrude within eye opening 108 (see, for example, FIG. 2B) of impeller 102 and are also configured for movement in a predetermined pattern (e.g., the circular pattern indicated by arrow A of FIGS. 2B and 3) when impeller assembly 100 is in use in a centrifugal pump.
• Referring to FIGS. [0021] 4A-4C, first impeller body 106 includes six curved vanes 114 disposed within eye opening 108. Each of the curved vanes 114 has a leading edge 116 that is located proximal to eye opening 108. First impeller body 106, curved vanes 114 and winglets 104 may be formed of any suitable material known to one skilled in the art including, but not limited to, PET white plastic.
• In the embodiment of FIGS. 2A, 2B, and [0022] 4A-4C, a winglet 104 is coupled to the leading edge 116 of each curved vane 114 by, for example, being formed as a unitary whole with curved vanes 114 of first impeller body 106. Preferably, each winglet 104 is machine or molded as a solid part of a corresponding impeller vane but may also be a separate piece coupled appropriately, as one skilled in the art will understand, to a corresponding leading edge. Therefore, when first impeller body 106 and curved vanes 114 are rotated (e.g., at a rotation speed in the range of 10 rpm to 3,500 rpm), winglets 104 move in a circular pattern within eye opening 108.
• Preferably, entrance vane angles are selected from a chart provided in various engineering books, such as, for example, “The Pump Hand Book.” Such a chart allows one skilled in the art to select a preferred vane entrance angle using desired impeller efficiency and impeller specific speed. [0023]
• [0024] Winglets 104 are configured to operate as rudimentary wings (i.e., airfoils) during movement in the predetermined pattern. This airfoil characteristic of winglets 104 is illustrated in FIG. 3. Winglets 104 have a trapezium (either quadrilateral or trapezoidal) cross-sectional shape and may be considered to possess a “top” side 200 and a “bottom” side 202. Thus, winglets 104 substantially fill corresponding vanes 114 as may be seen in FIG. 4C and therefore the trapezium shape is preferable. The dimensions of sides 200, 202 are likewise selected to substantially fill vanes 114. Once apprised of the present disclosure, one skilled in the art will recognize that other winglets of other cross-sectional shapes may be employed such as, for example, triangular or oblong cross-sectional shapes.
• When a fluid (e.g., water or air) flows [0025] past winglet 104 it travels farther along top side 200 than over bottom side 202 (as illustrated by the dashed arrows of FIG. 3) creating a vacuum differential or lift effect within eye opening 108. This effect facilitates evacuation of gas from a centrifugal pump during a self-priming process. In addition, the movement of winglet 104 serves to divide (i.e., break-up) large air bubbles into smaller gas bubbles that are more readily mixed with liquid and evacuated during a self-priming process.
• The provision of winglet(s) that protrude into the eye opening of impeller assemblies according to one exemplary embodiment of the present invention has been demonstrated to significantly reduce the time period required for self-priming processes. For example, test results indicate that a conventional self-priming centrifugal pump that required five minutes to complete self-priming when pumping water required only thirty seconds when winglets were provided in the eye opening of the centrifugal pump. [0026]
• It should be understood that various alternatives to the embodiments of the invention described herein may be employed in practicing the invention. It is intended that the following claims define the scope of the invention and that structures within the scope of these claims and their equivalents be covered thereby. [0027]

Claims (10)

What is claimed is:

1. An impeller assembly for a centrifugal pump, the impeller assembly comprising:

an impeller, the impeller including:

an impeller body with an eye opening therein, the eye opening configured for the passage of a fluid therethrough when the impeller assembly is in use;

at least one vane disposed about the eye opening, the at least one vane having a leading end; and

at least one winglet positioned to protrude into the eye opening of the impeller body.

2. The impeller assembly of claim 1, wherein a cross-section of the winglet is trapezoidal in shape.

3. The impeller assembly of claim 1, wherein a cross-section of the winglet is triangular in shape.

4. The impeller assembly of claim 1, wherein a cross-section of the winglet is oblong in shape.

5. The impeller assembly of claim 1, wherein the impeller body and winglet are configured as a unitary whole.

6. The impeller assembly of claim 5, wherein the at least one winglet is coupled to the leading edge of the at least one vane.

7. The impeller assembly of claim 6, wherein there are six vanes and six winglets and each of the six winglets is coupled to a leading edge of a different vane.

8. The impeller assembly of claim 1, wherein the impeller assembly is configured for use in a self-priming centrifugal pump.

9. An impeller assembly for a centrifugal pump, the impeller assembly comprising:

a rotatable impeller, the impeller including:

an impeller body with an eye opening therein, the eye opening configured for the passage of a fluid therethrough when the impeller assembly is in use;

at least one vane disposed about the eye opening, the at least one vane having a leading end; and

at least one winglet coupled to the leading edge of the at least one vane and positioned to protrude into the eye opening of the impeller.

10. The impeller assembly of claim 9, wherein there are six vanes and six winglets.

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