CENTRIFUGAL PUMP

Abstract

Embodiments of the disclosure include a centrifugal pump assembly including a pump housing defining a cavity and an impeller disposed within the cavity, the impeller being affixed to a shaft. The pump housing includes an inner surface having a geometric pattern configured in increase a turbulence of a fluid flow over the inner surface. The impeller includes one or more blades and a shroud. The inner surface of the pump housing and the shroud of the impeller define a leakage path.

Description

CROSS REFERENCE TO RELATED APPLICATIONS

This patent application claims priority to U.S. Provisional Patent Application Ser. No. 61/676,024 filed on Jul. 26, 2012 which is hereby incorporated herein by reference in its entirety.

FIELD OF THE INVENTION

Exemplary embodiments of the present invention relate to a pump assembly and, more particularly, to a centrifugal pump assembly with increased efficiency.

BACKGROUND

Shaft driven centrifugal pumps are often used for cooling of automotive engines. Centrifugal pumps operate by having water, or other fluid, directed axially into the pump and exit radially into one or more volutes. The shaft is typically mechanically driven, directly or indirectly by the engine crankshaft, and therefore rotates at some speed proportional to engine speed. Generally, centrifugal pumps include an impeller that rotates in a pocket. The impeller includes a shroud that is attached to the edge of the impeller vanes to help route the flow of fluid from a low pressure region at the pump's center to the high pressure region at the pump's outer perimeter.

Typically centrifugal pumps include a pump cavity that is located in close proximity to the shroud and a resulting leak path between the pump cavity and the shroud. The hydraulic efficiency of the pump is substantially affected by the clearance between the shroud and the pump cavity due to the leakage flow at this interface. Accordingly, the clearance between the shroud and the pump cavity is usually minimized. However, manufacturing tolerances place limits on the extent by which the clearance can be minimized.

In general, the design of the pump affects the efficiency of the pump. An increase in pump efficiency means less power is consumed in driving the pump, and can result in improved fuel economy. In addition, less than ideal fluid flow in the pump can result in flow separation in the flow field, which reduces pump capacity and may cause unwanted pump noise due to cavitation.

SUMMARY OF THE INVENTION

In an exemplary embodiment, a centrifugal pump assembly includes a pump housing defining a cavity. The pump housing includes an interior surface having a geometric pattern configured to increase turbulence of the fluid flow over the interior surface. The centrifugal pump assembly also includes an impeller disposed in the cavity, the impeller including one or more blades and a shroud. The centrifugal pump assembly further includes a shaft affixed to the impeller. The interior surface of the pump housing and the shroud of the impeller define a leakage path.

In another exemplary embodiment, a centrifugal pump assembly includes a pump housing defining a cavity, wherein the pump housing includes an interior surface. The centrifugal pump assembly also includes an impeller having one or more blades and a shroud disposed in the cavity. The centrifugal pump assembly also includes a shaft affixed to the impeller. The interior surface of the pump housing and an exterior surface of the shroud of the impeller define a leakage path. At least one of the interior surface of the pump housing and the exterior surface of the shroud include a geometric pattern configured to maximize a turbulence of a fluid flow in the leakage path.

The above features and advantages, and other features and advantages of the present invention are readily apparent from the following detailed description of the invention when taken in connection with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

Other objects, features, advantages and details appear, by way of example only, in the following detailed description of the embodiments, the detailed description referring to the drawings in which:

FIG. 1 is a cross sectional side view of a centrifugal pump assembly;

FIG. 2 is a plan view of a pump housing of the centrifugal pump assembly of FIG. 1; and

FIG. 3 a cross sectional side view of a centrifugal pump assembly in accordance with an exemplary embodiment;

FIG. 4 is a perspective view of an pump housing in accordance with an exemplary embodiment;

FIG. 5 is a plan view of a pump housing in accordance with another exemplary embodiment; and

FIG. 6 is a plan view of a pump housing in accordance with a further exemplary embodiment.

DESCRIPTION OF THE EMBODIMENTS

The following description is merely exemplary in nature and is not intended to limit the present disclosure, application or uses. It should be understood that throughout the drawings, corresponding reference numerals indicate like or corresponding parts and features.

Referring now to FIG. 1, a centrifugal pump assembly 100 is shown. The centrifugal pump assembly 100 includes a pump housing 110, which includes a cavity 112 and one or more volutes 114. In addition, the centrifugal pump assembly 100 includes a rotatable shaft 104 and a seal 106 that prevents fluid from passing out of the cavity 112 past the shaft 104. The centrifugal pump assembly 100 further includes an impeller 120 disposed inside of the cavity 112 such that the shaft 104 extends through an aperture 122 of the impeller 120. The impeller 120 is fit onto the shaft 104 for rotation with the shaft 104. The impeller 120 includes blades 124 and a shroud 126. The shroud 126 is affixed to the impeller 120 and is configured to rotate with the impeller 120. The shroud 126 of the impeller is disposed adjacent to an interior surface 116 of the cavity 112. The separation of the shroud 126 and the interior surface 116 of the cavity 112 define a leakage path 140. The hydraulic efficiency of the pump is substantially affected by the fluid flow in the leakage path 140. Accordingly, the clearance between the shroud 126 and the interior surface 116 of the cavity 112 has typically been minimized to minimize the fluid flow through the leakage path 140. Typically, as best illustrated by FIG. 2, the interior surface 116 has a generally smooth surface.

In exemplary embodiments, the interior surface 116 of the cavity 112 includes a geometric pattern that is configured to increase the turbulence of a fluid flow in the leakage path 140. By increasing the turbulence of the fluid flow through the leakage path 140, the volume of flow through the leakage path can be reduced and the volumetric efficiency of the pump 100 can be increased. In exemplary embodiments, the geometric pattern added to the interior surface 116 of the cavity does not result in a decrease in a required minimum physical separation between the shroud and the interior surface of the cavity. In exemplary embodiments, a wide variety of different geometries can be used to increase the turbulence of a fluid flow in the leakage path.

Referring now to FIG. 3, a cross-section of a centrifugal pump assembly 200 in accordance with an exemplary embodiment is shown. The centrifugal pump assembly 200 is a shaft driven, centrifugal automotive water pump, but the invention as claimed is not limited to such. The centrifugal pump assembly 200 includes a pump housing 210, which includes a cavity 212 and one or more volutes (not shown). In addition, the centrifugal pump assembly 200 includes a rotatable shaft 204 and a seal 206 that prevents fluid from passing out of the cavity 212 past the shaft 204. The centrifugal pump assembly 200 further includes an impeller 220 disposed inside of the cavity 212 such that the shaft 204 extends through an aperture 222 of the impeller 220. The impeller 220 is fit onto the shaft 204 for rotation with the shaft 204. The impeller 220 includes blades and a shroud 226. The shroud 226 is affixed to the impeller 220 and is configured to rotate with the impeller 220. The shroud 226 of the impeller 220 is disposed adjacent to an interior surface 216 of the cavity 212. The separation of the shroud 226 and the interior surface 216 of the cavity 212 define a leakage path 240.

In exemplary embodiments, the interior surface 216 of the cavity 212 includes a geometric pattern 230. In exemplary embodiments, the geometric pattern 230 may include a wide variety of different geometries that are configured to increase the turbulence of a fluid flow in the leakage path 240. By increasing the turbulence of a fluid flow in the leakage path 240 the volume of flow through the leakage path can be reduced and the hydraulic efficiency of the pump can be increased. In an alternative exemplary embodiment, the geometric pattern configured to increase the turbulence of a fluid flow in the leakage path 240 may be disposed on an exterior surface of the shroud 226 adjacent to the interior surface 216 of the cavity 212. In yet another exemplary embodiment, geometric patterns configured to increase the turbulence of a fluid flow in the leakage path 240 may be disposed on both the exterior surface of the shroud 226 and the interior surface 216 of the cavity 212. In exemplary embodiments, the geometric pattern of the interior surface 216 of the cavity 212 and the shroud 226 form a labyrinth seal. In general, labyrinth seals provide non-contact sealing by limiting the passage of fluid through chambers by the formation of controlled fluid vortices that result from flow over sharp edge conditions or through a torturous path.

Referring now to FIG. 4, a pump housing 310 in accordance with an exemplary embodiment is shown. As illustrated, the interior surface 316 includes a geometric pattern 330 configured to increase the turbulence of a fluid flow across the interior surface 316. In exemplary embodiments the geometric pattern 330 may include a series of sharp edges in the form of concentric ribs 332 that project upwards toward the shroud of the impeller. In exemplary embodiments, the sharp edges of the ribs 332 cause the leakage flow to locally separate from each corner which limits the effective flow cross-sectional area and thus reduces the extent of leakage flow.

Referring now to FIG. 5, a pump housing 410 in accordance with another exemplary embodiment is shown. As illustrated, the interior surface 416 includes a geometric pattern 430 configured to increase the turbulence of a fluid flow across the interior surface 416. In exemplary embodiments the geometric pattern 430 may include a series of concentric labyrinth rings 432 that are attached to form a screw that project upwards toward the shroud of the impeller. In exemplary embodiments, the top edges of the rings 432 cause the leakage flow to locally separate from each corner which increases limits the effective flow cross-sectional area and thus reduces the extent of leakage flow.

Referring now to FIG. 6, a pump housing 510 in accordance with a further exemplary embodiment is shown. As illustrated, the interior surface 516 includes a geometric pattern 530 configured to increase the turbulence of a fluid flow across the interior surface 516. In exemplary embodiments the geometric pattern 530 may include a plurality of protrusions 532 that project upwards toward the shroud of the impeller. In exemplary embodiments, the protrusion 532 may have a stepped shape as illustrated or may have a smooth surface. In exemplary embodiments, the protrusions 532 cause the leakage flow to be locally redirected at each protrusion 532 which increases the length of flow path and resulting pressure drop and thus reduces the extent of leakage flow. In exemplary embodiment, the plurality of protrusions 532 may be arranged in a wide variety of configurations and each of the plurality of protrusions 532 may have a wide variety of shapes. For example, the protrusions 532 may have a hemi-spherical shape, a pyramid shape, a conical shape, or any other suitable shape. In exemplary embodiments the arrangement and shape of the plurality of protrusions 532 on the interior surface 516 may be optimized to maximize the turbulence induced by the protrusions 532 on a fluid flow over the interior surface 516.

It will be appreciated by those of ordinary skill in the art that the geometries disposed on the interior surface of the cavity illustrated in FIGS. 4-6 are provided for exemplary purposed only and that scope of this disclosure is not intended to be limited to the geometries illustrated.

In exemplary embodiments, by increasing the turbulence of a fluid flow in the leakage path of the centrifugal pump assembly the efficiency of the centrifugal pump can be increased. For example, by reducing the fluid flow in the leakage path the amount of fluid flow through the volutes can be increased without requiring additional power to operate the pump. While the reduction of leakage flow may improve the pump's volumetric efficiency, it also has the potential of adversely affecting its mechanical efficiency. However, it has been found that the improvement in volumetric efficiency is greater that the loss in mechanical efficiency and thus the overall hydraulic efficiency may be improved by 1-2%.

In exemplary embodiments, the pump housing may be cast aluminum and the geometric pattern may be formed either during the casting process or may be machined into the interior surface of the pump housing after the pump housing is cast. In other exemplary embodiments, the pump housing may be made of a composite material and the geometric pattern is formed on the interior surface of the pump housing during the fabrication process.

While the invention has been described with reference to exemplary embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope thereof. Therefore, it is intended that the invention not be limited to the particular embodiments disclosed as the best mode contemplated for carrying out this invention, but that the invention will include all embodiments falling within the scope of the present application.

Claims

1. An centrifugal pump assembly comprising:

a pump housing defining a cavity, wherein the pump housing comprises an interior surface having a geometric pattern configured in increase a turbulence of a fluid flow over the inner surface;

an impeller disposed in the cavity, wherein the impeller comprises one or more blades and a shroud; and

a shaft affixed to the impeller;

wherein the interior surface of the pump housing and the shroud of the impeller define a leakage path.

2. The centrifugal pump assembly of claim 1, wherein the geometric pattern includes a series of concentric ribs.

3. The centrifugal pump assembly of claim 1, wherein the geometric pattern includes a series of concentric labyrinth rings.

4. The centrifugal pump assembly of claim 1, wherein the geometric pattern includes a plurality of protrusions that project towards the shroud.

5. The centrifugal pump assembly of claim 4, wherein the plurality of protrusions have a hemi-spherical shape, a pyramid shape, or a conical shape.

6. The centrifugal pump assembly of claim 1, wherein the geometric pattern is configured to maximize a turbulence of a fluid flow in the leakage path, wherein an increase in the turbulence of the fluid flow in the leakage path results in a reduction of a volume of the fluid flow.

7. An centrifugal pump assembly comprising:

a pump housing defining a cavity, wherein the pump housing comprises an interior surface;

an impeller disposed in the cavity, wherein the impeller comprises one or more blades and a shroud;

a shaft affixed to the impeller;

wherein the interior surface of the pump housing and an exterior surface of the shroud of the impeller define a leakage path; and

wherein at least one of the interior surface of the pump housing and the exterior surface of the shroud include a geometric pattern configured to maximize a turbulence of a fluid flow in the leakage path, wherein an increase in the turbulence of the fluid flow in the leakage path results in a reduction of a volume of the fluid flow.

8. The centrifugal pump assembly of claim 7, wherein the geometric pattern includes a series of concentric ribs.

9. The centrifugal pump assembly of claim 7, wherein the geometric pattern includes a series of concentric labyrinth rings.

10. The centrifugal pump assembly of claim 7, wherein the geometric pattern includes a plurality of protrusions that project towards the shroud.

11. The centrifugal pump assembly of claim 7, wherein the pump housing is formed by casting aluminum and the geometric pattern is formed during the casting process.

12. The centrifugal pump assembly of claim 7, wherein the pump housing is formed by casting aluminum and the geometric pattern is formed by machining the pump housing.