HEAT PIPE ASSEMBLY FOR DISSIPATING HEAT IN A DRAIN PUMP

Abstract

A washing machine appliance is provided including a sump for collecting wash fluid and a pump assembly fluidly coupled to the sump for urging a flow of wash fluid. The pump assembly includes a pump housing, a pump impeller, and a drive motor for selectively rotating the pump impeller. A heat pipe assembly extends between the drive motor and the flow of wash fluid to transfer thermal energy generated by the motor to the wash fluid. For example, an evaporator section of the heat pipe may be in direct contact with the drive motor and a condenser section of the heat pipe may be positioned within pump housing.

Description

FIELD OF THE INVENTION

The present subject matter relates generally to drain pump assemblies for washing machine appliances, or more specifically, to heat pipe assemblies for use with drain pump assemblies

BACKGROUND OF THE INVENTION

Washing machine appliances generally include a tub for containing water or wash fluid, e.g., water and detergent, bleach, and/or other wash additives. A basket is rotatably mounted within the tub and defines a wash chamber for receipt of articles for washing. During normal operation of such washing machine appliances, the wash fluid is directed into the tub and onto articles within the wash chamber of the basket. The basket or an agitation element can rotate at various speeds to agitate articles within the wash chamber, to wring wash fluid from articles within the wash chamber, etc.

During a spin or drain cycle, a drain pump assembly may operate to discharge water from within sump. Such drain pumps typically include an impeller positioned within a pump housing and an electric drive motor for rotating the impeller and discharging wash fluid. However, during extended pumping action, the core of the electric drive motor can get very warm and can make the pump weaker. For example, the pump's starting torque reduces when the drive motor gets very warm. In extreme cases, the drive motor even can reach a thermal cut off point where the pump assembly shuts down. Conventional washing machine drain pumps do not have integrated cooling mechanisms that actively help in dissipating heat generated in the motor core. Thus, heat generated by the winding in the motor core normally dissipates slowly to the surrounding air.

Accordingly, a washing machine appliance having an improved drain pump assembly would be desirable. More particularly, a drain pump assembly including a heat pipe for dissipating heat and facilitating prolonged pumping operation would be particularly beneficial.

BRIEF DESCRIPTION OF THE INVENTION

Advantages of the invention will be set forth in part in the following description, or may be apparent from the description, or may be learned through practice of the invention.

In accordance with one exemplary embodiment of the present disclosure, a washing machine appliance is provided including a sump for collecting wash fluid and a pump assembly in fluid communication with the sump for selectively urging a flow of wash fluid from the sump. A heat pipe assembly provides thermal communication between the pump assembly and the flow of wash fluid for transferring thermal energy from the pump assembly to the flow of wash fluid.

In accordance with another exemplary embodiment of the present disclosure, a washing machine appliance is provided including a sump for collecting wash fluid. A pump housing is in fluid communication with the sump, a pump impeller rotatably is mounted within the pump housing, and a drive motor selectively rotates the pump impeller to urge a flow of wash fluid within the pump housing. A heat pipe assembly includes an evaporator section and a condenser section, the heat pipe assembly providing thermal communication between the drive motor and the flow of wash fluid.

These and other features, aspects and advantages of the present invention will become better understood with reference to the following description and appended claims. The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

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.

FIG. 1 provides a perspective view of an exemplary washing machine appliance according to an exemplary embodiment of the present subject matter.

FIG. 2 provides a side cross-sectional view of the exemplary washing machine appliance of FIG. 1.

FIG. 3 provides a rear, perspective view of a drain pump assembly and a water level detection system according to an exemplary embodiment of the present subject matter.

FIG. 4 provides a side, perspective view of the exemplary drain pump assembly of FIG. 3 according to an embodiment of the present subject matter.

FIG. 5 provides an exploded view of the exemplary drain pump assembly of FIG. 4 according to an embodiment of the present subject matter.

FIG. 6 provides a side, schematic view of the exemplary drain pump assembly of FIG. 3 including a heat pipe assembly according to one embodiment of the present subject matter.

FIG. 7 provides a side, schematic view of the exemplary drain pump assembly of FIG. 3 including a heat pipe assembly according to another embodiment of the present subject matter.

FIG. 8 provides a top, schematic view of the exemplary drain pump assembly of FIG. 3 including a heat pipe assembly according to another embodiment of the present subject matter.

Repeat use of reference characters in the present specification and drawings is intended to represent the same or analogous features or elements of the present invention.

DETAILED DESCRIPTION

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.

As used herein, the terms “upstream” and “downstream” refer to the relative direction with respect to fluid flow in a fluid pathway. For example, “upstream” refers to the direction from which the fluid flows, and “downstream” refers to the direction to which the fluid flows. Furthermore, as used herein, terms of approximation, such as “approximately,” “substantially,” or “about,” refer to being within a ten percent margin of error.

Referring now to the figures, FIG. 1 is a perspective view of an exemplary horizontal axis washing machine appliance 100 and FIG. 2 is a side cross-sectional view of washing machine appliance 100. As illustrated, washing machine appliance 100 generally defines a vertical direction V, a lateral direction L, and a transverse direction T, each of which is mutually perpendicular, such that an orthogonal coordinate system is generally defined. Washing machine appliance 100 includes a cabinet 102 that extends between a top 104 and a bottom 106 along the vertical direction V, between a left side 108 and a right side 110 along the lateral direction L, and between a front 112 and a rear 114 along the transverse direction T.

Referring to FIG. 2, a wash basket 120 is rotatably mounted within cabinet 102 such that it is rotatable about an axis of rotation A. A motor 122, e.g., such as a pancake motor, is in mechanical communication with wash basket 120 to selectively rotate wash basket 120 (e.g., during an agitation or a rinse cycle of washing machine appliance 100). Wash basket 120 is received within a wash tub 124 and defines a wash chamber 126 that is configured for receipt of articles for washing. The wash tub 124 holds wash and rinse fluids for agitation in wash basket 120. As used herein, “wash fluid” may refer to water, detergent, fabric softener, bleach, or any other suitable wash additive or combination thereof. Indeed, for simplicity of discussion, these terms may all be used interchangeably herein without limiting the present subject matter to any particular “wash fluid.”

Wash basket 120 may define one or more agitator features that extend into wash chamber 126 to assist in agitation and cleaning articles disposed within wash chamber 126 during operation of washing machine appliance 100. For example, as illustrated in FIG. 2, a plurality of ribs 128 extends from basket 120 into wash chamber 126. In this manner, for example, ribs 128 may lift articles disposed in wash basket 120 during rotation of wash basket 120.

Referring generally to FIGS. 1 and 2, cabinet 102 also includes a front panel 130 which defines an opening 132 that permits user access to wash chamber 126 of wash basket 120. More specifically, washing machine appliance 100 includes a door 134 that is positioned over opening 132 and is rotatably mounted to front panel 130. In this manner, door 134 permits selective access to opening 132 by being movable between an open position (not shown) facilitating access to a wash chamber 126 and a closed position (FIG. 1) prohibiting access to wash chamber 126.

A window 136 in door 134 permits viewing of wash chamber 126 when door 134 is in the closed position, e.g., during operation of washing machine appliance 100. Door 134 also includes a handle (not shown) that, e.g., a user may pull or push when opening and closing door 134. Further, although door 134 is illustrated as mounted to front panel 130, it should be appreciated that door 134 may be mounted to another side of cabinet 102 or any other suitable support according to alternative embodiments.

Referring again to FIG. 2, wash basket 120 also defines a plurality of perforations 140 in order to facilitate fluid communication between an interior of basket 120 and wash tub 124. A sump 142 is defined by wash tub 124 at a bottom of wash tub 124 along the vertical direction V. Thus, sump 142 is configured for receipt of and generally collects wash fluid during operation of washing machine appliance 100. For example, during operation of washing machine appliance 100, wash fluid may be urged by gravity from basket 120 to sump 142 through plurality of perforations 140.

A drain pump assembly 144 is located beneath wash tub 124 and is in fluid communication with sump 142 for periodically discharging soiled wash fluid from washing machine appliance 100. Drain pump assembly 144 may generally include a drain pump 146 which is in fluid communication with sump 142 and with an external drain 148 through a drain hose 150. During a drain cycle, drain pump 146 urges a flow of wash fluid from sump 142, through drain hose 150, and to external drain 148. More specifically, as described in detail below in reference to FIGS. 3 through 9, drain pump 146 includes a motor which is energized during a drain cycle such that drain pump 146 draws wash fluid from sump 142 and urges it through drain hose 150 to external drain 148.

A spout 154 is configured for directing a flow of fluid into wash tub 124. For example, spout 154 may be in fluid communication with a water supply (not shown) in order to direct fluid (e.g., clean water) into wash tub 124. Spout 154 may also be in fluid communication with the sump 142. For example, pump assembly 144 may direct wash fluid disposed in sump 142 to spout 154 in order to circulate wash fluid in wash tub 124.

As illustrated in FIG. 2, a detergent dispenser 156 may be slidably mounted within front panel 130. Detergent dispenser 156 receives a wash additive (e.g., detergent, fabric softener, bleach, or any other suitable liquid or powder) and directs the fluid additive to wash tub 124 during operation of washing machine appliance 100. According to the illustrated embodiment, detergent dispenser 156 may also be fluidly coupled to spout 154 to facilitate the complete and accurate dispensing of wash additive.

In addition, a water supply valve 158 may provide a flow of water from a water supply source (such as a municipal water supply) into detergent dispenser 156 and into wash tub 124. In this manner, water supply valve 158 may generally be operable to supply water into detergent dispenser 156 to generate a wash fluid, e.g., for use in a wash cycle, or a flow of fresh water, e.g., for a rinse cycle. It should be appreciated that water supply valve 158 may be positioned at any other suitable location within cabinet 102.

A control panel 160 including a plurality of input selectors 162 is coupled to front panel 130. Control panel 160 and input selectors 162 collectively form a user interface input for operator selection of machine cycles and features. For example, in one embodiment, a display 164 indicates selected features, a countdown timer, and/or other items of interest to machine users.

Operation of washing machine appliance 100 is controlled by a controller or processing device 166 (FIG. 1) that is operatively coupled to control panel 160 for user manipulation to select washing machine cycles and features. In response to user manipulation of control panel 160, controller 166 operates the various components of washing machine appliance 100 to execute selected machine cycles and features.

Controller 166 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, controller 166 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 160 and other components of washing machine appliance 100 may be in communication with controller 166 via one or more signal lines or shared communication busses.

During operation of washing machine appliance 100, laundry items are loaded into wash basket 120 through opening 132, and washing operation is initiated through operator manipulation of input selectors 162. Wash tub 124 is filled with water, detergent, and/or other fluid additives, e.g., via spout 154 and or detergent dispenser 156. One or more valves (e.g., water supply valve 158) can be controlled by washing machine appliance 100 to provide for filling wash basket 120 to the appropriate level for the amount of articles being washed and/or rinsed. By way of example for a wash mode, once wash basket 120 is properly filled with fluid, the contents of wash basket 120 can be agitated (e.g., with ribs 128) for washing of laundry items in wash basket 120.

After the agitation phase of the wash cycle is completed, wash tub 124 can be drained. Laundry articles can then be rinsed by again adding fluid to wash tub 124, depending on the particulars of the cleaning cycle selected by a user. Ribs 128 may again provide agitation within wash basket 120. One or more spin cycles may also be used. In particular, a spin cycle may be applied after the wash cycle and/or after the rinse cycle in order to wring wash fluid from the articles being washed. During a final spin cycle, basket 120 is rotated at relatively high speeds and drain pump assembly 144 may discharge wash fluid from sump 142. After articles disposed in wash basket 120 are cleaned and/or washed, the user can remove the articles from wash basket 120, e.g., by opening door 134 and reaching into wash basket 120 through opening 132.

While described in the context of a specific embodiment of horizontal axis washing machine appliance 100, using the teachings disclosed herein it will be understood that horizontal axis washing machine appliance 100 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, e.g., vertical axis washing machine appliances.

Referring now to FIG. 3, drain pump assembly 144 that may be used within washing machine appliance 100 will be described according to an exemplary embodiment. As shown, sump 142 defines a drain basin at a lowest point of wash tub 124 for collecting wash fluid under the force of gravity. Drain pump assembly 144 is positioned proximate bottom 106 of cabinet and a sump hose 172 extends between sump 142 and an intake 174 of drain pump 146. According to the illustrated embodiment, drain pump 146 is a centrifugal pump configured for urging wash fluid that collects in sump 142 and sump hose 172 through a pump discharge 176, through drain hose 150, and to external drain 148. However, it should be appreciated that the drain pump assembly 144 and the sump drainage configuration illustrated herein are only exemplary and not intended to limit the scope of the present subject matter. For example, drain pump 146 may have a different configuration or position, may be attached directly to sump 142 bypassing the need for sump hose 172, may include one or more filtering mechanisms, etc.

Referring now specifically to FIGS. 4 and 5, drain pump 146 generally includes a pump housing 200, a pump impeller 202 rotatably mounted within pump housing 200, and a drive motor 204 that is operably coupled with pump impeller 202 for selectively rotating pump impeller 202 to urge a flow of wash fluid (e.g., as identified by arrows 206). More specifically, pump housing 200 may define pump intake 174 through which wash fluid may be channeled from sump 142. In addition, pump housing 200 may define a volute 210 within which pump impeller 202 is positioned for urging the flow of wash fluid 206 and a discharge conduit 212 that is positioned downstream from volute 210 and is fluidly coupled to drain hose 150.

Drive motor 204 may generally be any suitable electric motor which is operably coupled with pump impeller 202. For example, drive motor 204 may be a brushless DC electric motor, e.g., a pancake motor, an AC motor, an induction motor, a permanent magnet synchronous motor, or any other suitable type of motor. As illustrated, drive motor 204 generally includes a stator 220 positioned within a motor housing (not shown) and a rotor 222 rotatably positioned within the stator 220.

Stator 220 may be mechanically coupled within the motor housing (e.g., by one or more mechanical fasteners or through a compression fit) such that rotation relative to motor housing is prevented. By contrast, rotor 222 is rotatably mounted using one or more bearings 224. When energized with the appropriate power, rotor 222 is caused to rotate while stator 220 remains fixed. For example, according to an exemplary embodiment, stator 220 includes magnetic windings 226 wound around a lamination core 228. Each magnetic winding 226 may be formed from insulated conductive wire. When assembled, the stator 220 may be circumferentially positioned about rotor 222 to electromagnetically engage and drive rotation of rotor 222.

According to the illustrated embodiment, pump housing 200 is positioned above drive motor 204 along the vertical direction V. In addition, pump impeller 202 may be operably coupled with drive motor 204 in any suitable manner. For example, pump impeller 202 may be mechanically coupled to rotor 222, e.g., by direct mounting to a rotor shaft. Alternatively, pump impeller 202 may be magnetically coupled to rotor 222. Although an exemplary drive motor 204 is described herein, it should be appreciated that according to alternative embodiments, any other suitable drive motor may be used having any other type, configuration, or orientation.

Notably, drive motor 204 has a tendency to heat up during operation of drain pump assembly 144. In particular, if the drain cycle lasts long enough or the load on drive motor 204 is excessively large, drive motor 204 may reach a thermal cut-off temperature at which point drain pump assembly 144 shuts down altogether. Aspects of the present subject matter are directed to systems for regulating the temperature generated by drive motor 204, thereby avoiding high temperatures which can result operational issues for drive motor 204.

Specifically, referring now to FIGS. 6 through 8, washing machine appliance 100 may further include a heat pipe assembly 240 for providing thermal communication between pump assembly 144 and the flow of wash fluid 206 for transferring thermal energy from pump assembly 144 to the flow of wash fluid 206. More specifically, heat pipe assembly 240 is generally configured for cooling drive motor 204 of pump assembly 144 to avoid high temperature operation and permit drive motor 204 to operate for longer or higher-load periods without reaching a thermal cut-off point or temperature. In general, heat pipe assembly 240 is a type of heat exchanger used to transfer thermal energy through the evaporation and condensation of a working fluid, as described in more detail below

As shown, heat pipe assembly 240 includes one or more heat pipes 242 which each include a sealed casing 244 containing a working fluid 246 within casing 244. The casing 244 is preferably constructed of a material with a high thermal conductivity, such as a metal, such as copper or aluminum. In some embodiments, the working fluid 246 may be water. In other embodiments, suitable working fluids for the heat pipe 242 include acetone, methanol, ethanol, or toluene. Any suitable fluid may be used for working fluid 246, e.g., any fluid that is compatible with the material of the casing 244 and is suitable for the desired operating temperature range.

According to the illustrated embodiment, heat pipe 242 generally extends between a condenser section 248 at one end of heat pipe 242 and an evaporator section 250 at an opposite end of heat pipe 242. The working fluid 246 contained within the casing 244 of the heat pipe 242 absorbs thermal energy at the evaporator section 250, whereupon the working fluid 246 travels in a gaseous state from the evaporator section 250 to the condenser section 248. At the condenser section 248, the gaseous working fluid 246 condenses to a liquid state and thereby releases thermal energy. Notably, by positioning condenser section 248 with in the flow of wash fluid 206, which is moving any time drive motor 204 is running and is cooler than working fluid 246, a high rate of thermal transfer may be achieved.

According to an exemplary embodiment, heat pipe 242 may include a plurality of surface aberrations, protrusions, or fins 252 for increasing the rate of thermal transfer. In this regard, fins 252 may be provided on an external surface of the casing 244 at either or both of the condenser section 248 and the evaporator section 250. Fins 252 may provide an increased contact area between the heat pipe 242 and drive motor 204 or the flow of wash fluid 206. Fins 252 are particularly advantageous at the condenser section 248 where they readily discharge heat to the flow of wash fluid 206. According to alternative embodiments, no fins 252 are used and casing 244 is simply a smooth heat exchange pipe.

In general, evaporator section 250 may be physically connected to drive motor 204, may be positioned adjacent to drive motor 204, or may otherwise be in thermal communication with drive motor 204. Thus, as drive motor 204 heats up during operation, thermal energy from drive motor 204 may transfer to working fluid 246, which evaporates and travels through heat pipe 242 toward condenser section 248. Thermal energy from the evaporated working fluid 246 is then transferred through casing 244 and fins 252 to the flow of wash fluid 206. As the working fluid 246 cools, it will condense and flow in liquid form back to the evaporator section 250, e.g., by gravity and/or capillary flow.

According to exemplary embodiments, heat pipe 242 may further include an internal wick structure 260 to transport liquid working fluid 246 from the condenser section 248 to the evaporator section 250 by capillary flow. In some embodiments, the heat pipe 242 may be constructed and arranged such that the liquid working fluid 246 returns to the evaporator section 250 by gravity flow, including solely by gravity flow. For example, heat pipe 242 may be arranged with the condenser section 248 positioned above the evaporator section 250 along the vertical direction V such that condensed working fluid 246 in a liquid state may flow from the condenser section 248 to the evaporator section 250 by gravity. In such embodiments, where the liquid working fluid 246 may return to the evaporator section 250 by gravity, wick structure 260 may be omitted whereby the liquid working fluid 246 may return to the evaporator section 250 solely by gravity flow.

Notably, certain positions, orientations, and configurations of heat pipe assembly 240 may provide increased rates of thermal transfer from drive motor 204 to the flow of wash fluid 206. Several exemplary configurations are illustrated in the figures and described below for the purpose of explaining aspects of the present subject matter. However, it should be appreciated that these configurations are only exemplary and are not intended to limit the subject matter of the present application in any manner.

For example, evaporator section 250 of heat pipe 242 may be positioned in direct contact with windings 226 and/or lamination core 228 of drive motor 204. In this manner, heat pipes 242 may extract thermal energy from one of the hottest regions within pump assembly 144. In addition, heat pipe 242 may be molded directly into pump housing 200 and/or motor housing. In addition, according to exemplary embodiments, evaporator section 250 may extend vertically along drive motor 204, may wrap around the drive motor 204, and may be split into multiple capillary pipes or tubes for facilitating improved and even heat transfer from drive motor 204 to working fluid 246.

In addition, condenser section 248 of heat pipe 242 may be positioned within pump housing 200 at any suitable location placing working fluid 246 in thermal communication with the flow of wash fluid 206. For example, condenser section 248 may terminate within volute 210. Alternatively, condenser section may pass through pump housing 200 and extend along discharge conduit 212. In addition, condenser section 248 may be positioned around pump impeller 202 or may be positioned between pump impeller 202 and drive motor 204. In this regard, condenser section 248 of heat pipe 242 may include a loop of pipe 270 that extends around pump housing 200 within volute 210. For example, loop of pipe 270 may extend in a radial plane defined by a radial direction R perpendicular to the vertical direction V. In this manner, the surface area of heat pipe 242 in thermal communication with the flow of wash fluid 206 within pump housing 200 may be maximized thereby increasing the rate of thermal transfer from the working fluid 246, through heat pipe 242, and into the flow of wash fluid 206.

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.

Claims

1. A washing machine appliance comprising:

a sump for collecting wash fluid;

a pump assembly in fluid communication with the sump for selectively urging a flow of wash fluid from the sump; and

a heat pipe assembly providing thermal communication between the pump assembly and the flow of wash fluid for transferring thermal energy from the pump assembly to the flow of wash fluid.

2. The washing machine appliance of claim 1, wherein the heat pipe assembly comprises:

an evaporator section positioned at one end of the heat pipe assembly; and

a condenser section positioned at an opposite end of the heat pipe assembly.

3. The washing machine appliance of claim 1, wherein the heat pipe assembly comprises a plurality of heat pipes.

4. The washing machine appliance of claim 1, wherein the pump assembly comprises:

a pump housing;

a pump impeller rotatably mounted within the pump housing; and

a drive motor for selectively rotating the pump impeller to urge the flow of wash fluid within the pump housing.

5. The washing machine appliance of claim 4, wherein the heat pipe is molded into the pump housing.

6. The washing machine appliance of claim 4, wherein the drive motor is positioned below the pump housing along a vertical direction.

7. The washing machine appliance of claim 4, wherein the evaporator section of the heat pipe assembly is positioned in direct contact with a winding of the drive motor.

8. The washing machine appliance of claim 4, wherein the evaporator section of the heat pipe assembly is positioned in direct contact with a lamination core of the drive motor.

9. The washing machine appliance of claim 4, wherein the condenser section of the heat pipe assembly is positioned within the pump housing.

10. The washing machine appliance of claim 4, wherein the condenser section of the heat pipe assembly is positioned in a discharge conduit.

11. The washing machine appliance of claim 4, wherein the condenser section of the heat pipe assembly is positioned around the pump impeller.

12. The washing machine appliance of claim 4, wherein the condenser section of the heat pipe assembly is positioned between the pump impeller and the drive motor.

13. The washing machine appliance of claim 4, wherein the condenser section of the heat pipe assembly comprises a loop of pipe that extends around the pump housing within a radial plane.

14. A washing machine appliance comprising:

a sump for collecting wash fluid;

a pump housing in fluid communication with the sump;

a pump impeller rotatably mounted within the pump housing;

a drive motor for selectively rotating the pump impeller to urge a flow of wash fluid within the pump housing; and

a heat pipe assembly comprising an evaporator section and a condenser section, the heat pipe assembly providing thermal communication between the drive motor and the flow of wash fluid.

15. The washing machine appliance of claim 14, wherein the evaporator section is positioned in direct contact with a winding or a lamination core of the drive motor.

16. The washing machine appliance of claim 14, wherein the condenser section is positioned within the pump housing.

17. The washing machine appliance of claim 14, wherein the condenser section is positioned in a discharge conduit.

18. The washing machine appliance of claim 14, wherein the condenser section is positioned around the pump impeller.

19. The washing machine appliance of claim 14, wherein the condenser section comprises a loop of pipe that extends around the pump housing within a radial plane.