DRAIN PUMP VOLUTE WITH NOISE REDUCTION FEATURE

Abstract

A drain pump of a washing appliance includes a volute defined between an inlet and an outlet. The volute defines an axial direction, a radial direction perpendicular to the axial direction, and a circumferential direction extending around the axial direction. The volute further includes a groove formed in an internal surface of an upper portion of the volute. The groove is configured to divert a portion of fluid inside the volute towards the inlet.

Claims

1. A washing machine appliance defining a vertical direction, a lateral direction, and a transverse direction, the vertical direction, the lateral direction and the transverse direction are mutually perpendicular, the washing machine appliance comprising: a cabinet extending between a top and a bottom along the vertical direction; a wash tub mounted within the cabinet and configured for containing fluid during operation of the washing machine appliance; a wash basket rotatably mounted within the wash tub, the wash basket defining a wash chamber configured for receiving laundry articles; and a drain pump positioned below the wash tub along the vertical direction within the cabinet, the drain pump comprising a volute defined between an inlet and an outlet, the volute defining an axial direction, a radial direction perpendicular to the axial direction, and a circumferential direction extending around the axial direction, the volute comprising a groove formed in an internal surface of an upper portion of the volute, the groove configured to divert a portion of fluid inside the volute towards the inlet.

2. The washing machine appliance of claim 1, wherein the groove is one of a plurality of grooves, each groove of the plurality of grooves extending generally along the radial direction.

3. The washing machine appliance of claim 2, wherein one or more grooves of the plurality of grooves are positioned in an upstream side of the volute away from the discharge side.

4. The washing machine appliance of claim 2, wherein one or more grooves of the plurality of grooves are positioned in a discharge side of the volute.

5. The washing machine appliance of claim 1, further comprising a circumferential channel extending around the internal surface of the upper portion of the volute along the circumferential direction, the circumferential channel in fluid communication with the groove.

6. The washing machine appliance of claim 5, wherein the circumferential channel extends across an upstream side of the volute.

7. The washing machine appliance of claim 5, wherein the circumferential channel extends fully around the volute.

8. The washing machine appliance of claim 1, wherein the groove is in fluid communication with a linear channel in the outlet.

9. The washing machine appliance of claim 8, wherein the groove is positioned on a discharge side of the volute and in direct fluid communication with the linear channel in the outlet.

10. The washing machine appliance of claim 1, further comprising a circumferential channel extending around the internal surface of the upper portion of the volute along the circumferential direction, wherein the groove is one of a plurality of grooves, each groove of the plurality of grooves extending generally along the radial direction, and the circumferential channel is in fluid communication with each groove of the plurality of grooves.

11. A drain pump of a washing appliance, the drain pump comprising: a volute defined between an inlet and an outlet, the volute defining an axial direction, a radial direction perpendicular to the axial direction, and a circumferential direction extending around the axial direction, the volute further comprising: a groove formed in an internal surface of an upper portion of the volute; wherein the groove is configured to divert a portion of fluid inside the volute towards the inlet.

12. The drain pump of claim 11, wherein the groove is one of a plurality of grooves, each groove of the plurality of grooves extending generally along the radial direction.

13. The drain pump of claim 12, wherein the plurality of grooves are positioned in an upstream side of the volute away from the discharge side.

14. The drain pump of claim 12, wherein one or more grooves of the plurality of grooves are positioned in a discharge side of the volute.

15. The drain pump of claim 11, further comprising a circumferential channel extending around the internal surface of the upper portion of the volute along the circumferential direction, the circumferential channel in fluid communication with the groove.

16. The drain pump of claim 15, wherein the circumferential channel extends across a suction side of the volute.

17. The drain pump of claim 15, wherein the circumferential channel extends fully around the volute.

18. The drain pump of claim 11, wherein the groove is in fluid communication with a linear channel in the outlet.

19. The drain pump of claim 18, wherein the groove is positioned on a discharge side of the volute and in direct fluid communication with the linear channel in the outlet.

20. The drain pump of claim 11, further comprising a circumferential channel extending around the internal surface of the upper portion of the volute along the circumferential direction, wherein the groove is one of a plurality of grooves, each groove of the plurality of grooves extending generally along the radial direction, and the circumferential channel is in fluid communication with each groove of the plurality of grooves.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0009] A full and enabling disclosure of the present invention, including the best mode thereof, directed to one of ordinary skill in the art, is set forth in the specification, which makes reference to the appended figures.

[0010] FIG. 1 provides a perspective view of a washing machine appliance according to example embodiments of the present subject matter.

[0011] FIG. 2 provides a front cross-sectional view of the washing machine appliance of FIG. 1.

[0012] FIG. 3 provides a side view of a drain pump of a washing appliance in accordance with at least one embodiment of the present subject matter.

[0013] FIG. 4 provides an exploded view of the drain pump of FIG. 3.

[0014] FIG. 5 provides a section view of a volute in accordance with at least one embodiment of the present subject matter which may be incorporated into a drain pump such as the drain pump of FIG. 3.

[0015] FIG. 6 provides a bottom view of the volute of FIG. 5.

[0016] FIG. 7 provides a section view of a volute in accordance with at least one additional embodiment of the present subject matter which may be incorporated into a drain pump such as the drain pump of FIG. 3.

[0017] FIG. 8 provides a bottom view of the volute of FIG. 7.

[0018] FIG. 9 provides a section view of a volute in accordance with at least one additional embodiment of the present subject matter which may be incorporated into a drain pump such as the drain pump of FIG. 3.

[0019] FIG. 10 provides a perspective view of the volute of FIG. 9.

DETAILED DESCRIPTION

[0020] Reference now will be made in detail to embodiments of the invention, one or more examples of which are illustrated in the drawings. Each example is provided by way of explanation of the invention, not limitation of the invention. In fact, it will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the scope or spirit of the invention. For instance, features illustrated or described as part of one embodiment can be used with another embodiment to yield a still further embodiment. Thus, it is intended that the present invention covers such modifications and variations as come within the scope of the appended claims and their equivalents.

[0021] As used herein, the terms first, second, and third may be used interchangeably to distinguish one component from another and are not intended to signify location or importance of the individual components. As used herein, terms of approximation such as generally, about, or approximately include values within ten percent greater or less than the stated value. When used in the context of an angle or direction, such terms include within thirty degrees greater or less than the stated angle or direction, e.g., generally vertical includes forming an angle of up to thirty degrees in any direction, e.g., clockwise or counterclockwise, with the vertical direction V.

[0022] FIG. 1 is a perspective view of a washing machine appliance 50 according to an example embodiment of the present disclosure. FIG. 2 provides a front, cross-sectional view of washing machine appliance 50. As may be seen in FIG. 1, washing machine appliance 50 includes a cabinet 52 and a cover 54. A backsplash 56 extends from cover 54, and a control panel 58 including a plurality of input selectors 60 is coupled to backsplash 56. Control panel 58 and input selectors 60 collectively form a user interface for operator selection of machine cycles and features. In some embodiments, a display 61 indicates selected features, a countdown timer, and/or other items of interest to users. A door 62 is mounted to cover 54 and is rotatable between an open position (not shown) facilitating access to a wash tub 64 (FIG. 2) located within cabinet 52 and a closed position (shown in FIG. 1) forming an enclosure over tub 64.

[0023] As may be seen in FIG. 2, tub 64 includes a bottom wall 66 and a sidewall 68. A wash drum or wash basket 70 is rotatably mounted within tub 64, defining an annulus 85 between the tub 64 and basket 70. In particular, basket 70 is rotatable about a central axis 69, which may, when properly balanced and positioned in the embodiment illustrated, be a vertical axis. Thus, washing machine appliance 50 is generally referred to as a vertical axis washing machine appliance. Basket 70 defines a wash chamber 73 for receipt of a load of articles for washing and extends, e.g., vertically, between a bottom portion 80 and a top portion 82. Basket 70 includes a plurality of openings or perforations 71 therein to facilitate fluid communication between an interior of basket 70 and tub 64.

[0024] In some embodiments, nozzle 72 is configured for flowing or directing a liquid into tub 64. In particular, nozzle 72 may be positioned at or adjacent top portion 82 of basket 70. Nozzle 72 may be in fluid communication with one or more water sources 75, 76 in order to direct liquid (e.g., water) into tub 64 and/or onto articles within chamber 73 of basket 70. For instance, a water inlet line 67 may connect to water sources 75, 76 to selectively receive water therefrom. Nozzle 72 may further include apertures 79 through which water may be sprayed into the tub 64. Apertures 79 may, for example, be tubes extending from the nozzles 72, as illustrated. Alternatively, apertures 79 may simply be holes defined in the nozzles 72 or any other suitable openings through which water may be sprayed. Nozzle 72 may additionally include other openings, holes, etc. (not shown) through which water may be flowed (i.e., sprayed or poured) into the tub 64.

[0025] A main valve 74 generally regulates the flow of liquid (e.g., water) through nozzle 72. For example, valve 74 can selectively adjust to a closed position in order to terminate or obstruct the flow of liquid through nozzle 72. When assembled and installed for use, the main valve 74 may be in fluid communication with one or more external liquid sources, such as a cold water source 75 and a hot water source 76. The cold water source 75 may, for example, be a commercial water supply, while the hot water source 76 may be, for example, a water heater. Such external water sources 75, 76 may supply water to the appliance 50 through the main valve 74. A cold water conduit 77 and a hot water conduit 78 may supply cold and hot water, respectively, from the sources 75, 76 through valve 74. Valve 74 may further be operable to regulate the flow of hot and cold liquid, and thus the temperature of the resulting liquid flowed into tub 64, such as through the nozzle 72.

[0026] An enclosed additive dispenser 84 may optionally be mounted or enclosed within cabinet 52 for directing an additive, such as detergent, bleach, liquid fabric softener, etc., into the tub 64. As illustrated, an enclosed dispenser 84 may be in fluid communication with nozzle 72 within cabinet 52. For instance, dispenser 84 may be in fluid communication with nozzle 72 such that water flowing through nozzle 72 flows through dispenser 84, mixing with additive at a desired time during operation to form a wash fluid, before being flowed into tub 64, e.g., through apertures 79. In alternative embodiments, nozzle 72 and dispenser 84 may be integral and directed into annulus 85, with a portion of dispenser 84 serving as the nozzle 72. In other alternative embodiments, a dispenser may be in fluid communication with annulus 85 separate from nozzle 72. Additive may thus be added from the dispenser by flowing directly from the dispenser into the annulus 85, while liquid is supplied to chamber 73 from nozzle 72. In further alternative embodiments, no additive dispenser is mounted or enclosed within cabinet 52.

[0027] A drain pump 90 (shown schematically in FIG. 2) is located beneath tub 64 and basket 70 for gravity assisted flow from tub 64 to drain pump 90. The drain pump 90 is connected to a drain line 93, e.g., at an outlet 206 of the drain pump 90, as described in more detail below, such that the drain pump 90 discharges wash fluid to the drain line 93. An agitation element 92, shown as an impeller in FIG. 2, may be disposed in basket 70 to impart an oscillatory motion to articles and liquid in chamber 73 of basket 70. In example embodiments, agitation element 92 includes a single action element (i.e., oscillatory only), double action (oscillatory movement at one end, single direction rotation at the other end) or triple action (oscillatory movement plus single direction rotation at one end, single direction rotation at the other end). As illustrated in FIG. 2, agitation element 92 is oriented to rotate about axis 69. Alternatively, basket 70 may provide such agitating movement, e.g., such that agitation element 92 is not required. In some embodiments, basket 70 and agitation element 92 are driven by a motor 94. Motor 94 may, for example, be a pancake motor, direct drive brushless motor, induction motor, or other motor suitable for driving basket 70 and agitation element 92. In some embodiments, motor 94 may be connected to basket 70 via a mode shifter 99. The mode shifter 99 may be selectively movable into and out of engagement with the basket 70. For example, the mode shifter 99 may engage the basket 70 so that basket 70 can be rotated by motor 94 during a spin cycle, and mode shifter 99 may disengage the basket 70 during an agitation cycle so that the motor 94 rotates the agitation element 92 independent of the basket 70. As motor output shaft 98 is rotated, basket 70 and agitation element 92 are operated for rotatable movement within tub 64, e.g., about axis 69. Washing machine appliance 50 may also include a brake assembly (not shown) selectively applied or released for respectively maintaining basket 70 in a stationary position within tub 64 or for allowing basket 70 to spin within tub 64.

[0028] Various sensors may additionally be included in the washing machine appliance 50. For example, a pressure sensor 96 may be positioned in the tub 64 as illustrated. Any suitable pressure sensor 96, such as an electronic sensor, a manometer, or another suitable gauge or sensor, may be utilized. The pressure sensor 96 may generally measure the pressure of water in the tub 64. This pressure can then be utilized to estimate the height or level of water in the tub 64. Additionally, a suitable speed sensor (not shown) can be provided to measure rotational speed of basket 70 and/or agitation element 92. Other suitable sensors, such as temperature sensors, etc., may additionally be provided in the washing machine appliance 50. The structure and function of such sensors is generally understood by those of skill in the art, and as such will not be described in further detail herein.

[0029] Operation of washing machine appliance 50 is generally controlled by an appliance processing device or controller 100 that is in communication with (e.g., electrically coupled to) the input selectors 60 for user manipulation to select washing machine cycles and features. As illustrated, the input selectors 60 may be knobs or dials. In various embodiments, the input selectors 60 may include one or more user input devices, such as switches, buttons, touchscreen interfaces, etc., as well as or instead of the illustrated example input selectors 60. Appliance controller 100 may further be in communication with (e.g., electrically coupled to) various other components of appliance 50, such as main valve 74, drain pump 90, motor 94, pressure sensor 96, and one or more other suitable sensors, etc. In response to user manipulation of the input selectors 60, appliance controller 100 may operate the various components of washing machine appliance 50 to execute selected machine cycles and features. In the illustrated example embodiment, the user interface, including the input selectors 60, is located on backsplash 56. It should be understood, however, that the controller 100 and the user interface may each be positioned in a variety of locations throughout washing machine appliance 50. Further, it should be understood that a remote interface, such as but not limited to an app running on a smartphone which communicates with the controller 100 wirelessly, e.g., via WIFI or BLUETOOTH, etc., may be provided as well as or instead of the input selectors 60.

[0030] Appliance controller 100 may include a memory and microprocessor, such as a general or special purpose microprocessor operable to execute programming instructions or micro-control code associated with a cleaning cycle. The memory may represent random access memory such as DRAM, or read only memory such as ROM or FLASH. In one embodiment, the processor executes programming instructions stored in memory. The memory may be a separate component from the processor or may be included onboard within the processor. Alternatively, appliance controller 100 may be constructed without using a microprocessor, e.g., using a combination of discrete analog and/or digital logic circuitry (such as switches, amplifiers, integrators, comparators, flip-flops, AND gates, and the like) to perform control functionality instead of relying upon software. Control panel 58 and other components of washing machine appliance 50, such as the door 62, drain pump 90, motor 94, valve 74, pressure sensor 96, and various other sensors, etc. may be in communication with appliance controller 100 via one or more signal lines or shared communication busses. It should be noted that controllers 100 as disclosed herein are capable of and may be operable to perform any methods and associated method steps as disclosed herein. For example, in some embodiments, methods disclosed herein may be embodied in programming instructions stored in the memory and executed by the controller 100.

[0031] It should be appreciated that the present subject matter is not limited to any particular style, model, or configuration of washing machine appliance. The exemplary embodiment depicted in FIGS. 1 and 2 is simply provided for illustrative purposes only. While described in the context of a specific embodiment of vertical axis washing machine appliance 50, it will be understood that vertical axis washing machine appliance 50 is provided by way of example only. Other washing machine appliances having different configurations, different appearances, and/or different features may also be utilized with the present subject matter as well. For example, different locations may be provided for the user interface, different configurations may be provided, e.g., horizontal axis washing machines, and other differences may be applied as well. Further, the noise-reducing features described herein may be useful in a drain pump included in other washing appliances more generally, e.g., other than washing machine appliances. For example, the noise-reducing features may be provided in a drain pump of a dishwashing appliance.

[0032] Turning now to FIGS. 3 and 4, an example embodiment of a drain pump 90 is illustrated. In various embodiments, the drain pump 90 may be directly attached to the wash tub 64, or may be connected to the wash tub 64 via a drain conduit 91, as shown in FIG. 2. The drain conduit 91 may be a hose, pipe, tube, or any other suitable conduit for flowing fluid, e.g., wash liquid, from the wash tub 64 to the drain pump 90, e.g., by gravity. It should be understood that the drain pump 90 as shown and described herein is provided in the context of a laundry appliance, e.g., the clothes washer or washing machine appliance shown in FIGS. 1 and 2 and described hereinabove, by way of example only. The drain pump 90 is not necessarily limited to use in a clothes washer, rather, the drain pump 90 may be useful in other washing appliances, such as a dishwashing appliance. Thus, for example, references herein to a washing appliance should be understood as inclusive of additional appliances as well as the clothes washer example.

[0033] The drain pump 90 includes a motor 200 in operative communication with an impeller 202. The motor 200 is configured to rotate the impeller 202. The drain pump 90 also includes an inlet 204, and outlet 206, and a volute 208 defined between the inlet 204 and the outlet 206. As shown in FIG. 2, the drain pump 90 is positioned below the wash tub 64 along the vertical direction V within the cabinet 52, whereby wash liquid may flow from the wash tub 64 to the inlet 204 of the drain pump 90 by gravity. The impeller 202 is positioned within the volute 208 when the drain pump 90 is assembled, such that the rotation of the impeller 202 urges fluid, e.g., wash liquid, though the volute 208, e.g., from the inlet 204 to the outlet 206. As illustrated in FIG. 3, fluid enters the volute 208 from the inlet 204 as indicated by arrow 203, e.g., from the drain conduit 91, and the fluid leaves the volute 208 from the outlet 206 as indicated by arrow 205. As illustrated in FIG. 4, the drain pump 90 defines a centerline 210.

[0034] As illustrated, e.g., in FIG. 5, the volute 208 defines an axial direction A, a radial direction R perpendicular to the axial direction A, and a circumferential direction C extending around the axial direction A. The axial direction A may be along or parallel to the centerline 210 of the drain pump 90. The volute 208 includes an upper portion 212 and a lower portion 214 spaced apart along the axial direction A. The upper portion 212 extends generally along the radial direction R, e.g., generally includes within plus or minus thirty degrees of the radial direction R, as noted above. The lower portion 214 of the volute 208 is configured for mounting on or attaching to the motor 200 of the drain pump 90. At least one groove 218 may be formed in an internal surface 216 of the upper portion 212 of the volute 208. The at least one groove 218 may be configured to divert a portion of fluid inside the volute 208 towards the inlet 204 and create a recirculation effect. For example, during operation of the washing appliance, e.g., when the pump evacuates all the fluid and runs with empty or near empty tub, the discharged fluid in the drain pipe oscillates and creates user perceptible periodic noise. Such oscillation of the discharged fluid in the drain pipe may be reduced or suppressed by recirculating the fluid inside the volute cavity. As such, the fluid in the re-directed fluid flow may provide a constant or consistent level of fluid in the volute 208, particularly at the impeller 202, whereby the generation of undesirable user-perceptible noise may be reduced or eliminated. In various embodiments, the fluid flowing through the volute 208 may be, e.g., used wash liquid from a washing appliance such as the washing machine appliance 50 or another washing appliance such as, e.g., a dishwasher appliance.

[0035] As may be seen in FIGS. 5 and 6, in some embodiments, the volute 208 may include a plurality of grooves 218 extending generally along the radial direction R. The grooves 218 may be generally linear, as in the illustrated example embodiments, may be curvilinear, e.g., generally tangential to the radial direction R, and/or one or more of the grooves 218 may include both linear and curvilinear portions. In some embodiments, a combination of linear grooves 218 and curvilinear grooves 218 may be provided. In various embodiments, at least some of the plurality of grooves 218 may be positioned in an upstream side 207 of the volute 208 away from the discharge side 209. Also shown in FIGS. 5 and 6 is a circumferential channel 220 extending around the internal surface 216 of the upper portion 212 of the volute 208 along the circumferential direction C. The circumferential channel 220 may be in fluid communication with each groove 218 of the plurality of grooves 218. For example, the circumferential channel 220 may be directly fluidly connected to each groove 218 of the plurality of grooves 218. For example, the circumferential channel 220 may be continuous with each groove 218 of the plurality of grooves 218. In the example embodiment illustrated by FIGS. 5 and 6, the circumferential channel 220 extends only across the upstream side 207 of the volute 208 and the plurality of groove 218 are formed only in the upstream side 207 of the volute 208. In operation, the rotation of the impeller 202 of the drain pump 90 within the volute 208 may impart an angular motion, e.g., along the circumferential direction C, to the fluid flowing through the volute 208. Such fluid which is urged through the volute 208 by the impeller 202, or at least a portion thereof, may flow into the circumferential channel 220 and from the circumferential channel 220 into each of the plurality of grooves 218.

[0036] The plurality of grooves 218 are formed and configured, e.g., due to the orientation of the grooves 218 generally along the radial direction R between the channel 220 and the inlet 204, to direct the fluid from the circumferential channel 220 inward, e.g., towards the centerline 210, within the volute 208, providing a more consistent level of fluid at the impeller 202, e.g., as compared to a volute lacking such channel(s) and/or groove(s). For example, as may be seen in FIG. 4, the impeller 202 may be generally positioned at or proximate to a center of the drain pump 90, e.g., a point along the centerline 210, and the inlet 204 of the drain pump 90 may also be centered on the centerline 210, e.g., a geometric center of the inlet 204 such as a center point of a cross-section of the inlet 204 may be positioned at a point along or close to the centerline 210, such that the impeller 202 is directly below or approximately directly below the inlet 204, such that the inwardly-directed fluid from the plurality of grooves 218 flows to the impeller 202. As used herein, approximately directly below includes the offset from the center of the impeller 202 to the center of the inlet 204 is within +/10%, such as within +/5%, such as within +/4%, such as within +/3%, such as within +/2%, such as within +/1%, such as within +/0.5% of the overall dimension of the inlet 204, e.g., where the inlet 204 is cylindrical, the diameter of the inlet 204.

[0037] As may be seen, e.g., in FIG. 6, each groove 218 may extend from an inlet 222 to an outlet 224. The inlet 222 of each groove 218 may be fluidly connected, e.g., directly fluidly connected, to the circumferential channel 220. The outlet 224 of each groove 218 may be in fluid communication with the inlet 204 of the drain pump upstream of the volute 208, e.g., upstream of the impeller 202 positioned within the volute 208.

[0038] As illustrated for example in FIGS. 7 and 8, in some embodiments, one or more grooves 218 of the plurality of grooves 218 may be positioned in a discharge side 209 of the volute 208. Further, in such embodiments, the circumferential channel 220 may extend fully around the volute 208, as best seen in FIG. 8. In embodiments such as the example embodiment illustrated in FIG. 8, the circumferential channel 220 extends across the upstream side 207 and across the discharge side 209 of the volute 208.

[0039] In some embodiments, the drain pump 90 may also include a linear channel 230 formed in an internal surface 232 of an upper portion 234 of the outlet 206. As shown in FIGS. 7 and 8, in some embodiments, the linear channel 230 may be in fluid communication with the plurality of grooves 218 via the circumferential channel 220. For example, in some embodiments, the linear channel 230 may be in direct fluid communication with, e.g., directly fluidly connected to, the circumferential channel 220, as shown in FIGS. 7 and 8. In operation, a portion of fluid flowing from the volute 208 via the outlet 206 may enter the linear channel 230 and be redirected from back into the volute 208 through the circumferential channel 220 and grooves 218 and onto the impeller 202, reducing or preventing the generation of undesirable noise.

[0040] FIGS. 9 and 10 illustrate an additional example embodiment wherein only a single groove 218 is provided. The groove 218 in FIGS. 9 and 10 is in fluid communication with the linear channel 230 in the outlet 206 of the drain pump 90. As shown for example in FIGS. 9 and 10, in some embodiments, the linear channel 230 may be in direct fluid communication with, e.g., directly fluidly connected to, the groove 218. In operation, a portion of fluid flowing from the volute 208 via the outlet 206 may enter the linear channel 230 and be redirected back into the volute 208 through the groove 218 and onto the impeller 202, reducing or preventing the generation of undesirable noise. Also as may be seen in FIGS. 9 and 10, the groove 218 may have a reverse taper. In some embodiments, the outlet 224 of the groove 218 may be significantly larger than the inlet 222 of the groove 218, for example, the outlet 224 may have a cross-sectional area about one and a half times that of the inlet 222 or more, such as about twice the cross-sectional area of the inlet 222, such as about three times the cross-sectional area of the inlet 222, or more.

[0041] As mentioned above, features illustrated or described as part of one embodiment can be used with another embodiment to yield a still further embodiment. For example, the groove 218 and the linear channel 230 in the outlet 206 of FIGS. 9 and 10 may be combined with the plurality of grooves 218 and/or the circumferential channel 220 in the upstream side 207 of the volute 208 of FIGS. 5 and 6.

[0042] This written description uses examples to disclose the invention, including the best mode, and also to enable any person skilled in the art to practice the invention, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the invention is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they include structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal languages of the claims.