Surface cleaning apparatus

A cleaning apparatus for a floor surface comprises a fluid delivery system having a supply tank for storing cleaning fluid and a fluid distributor for delivering the cleaning fluid to a surface to be cleaned. An air pathway is provided in the cleaning apparatus for removing heated air from the motor. In operation, heat from the heated air is transferred to the cleaning fluid in the supply tank.

BACKGROUND OF THE INVENTION

Extractors are well-known surface cleaning devices for deep cleaning carpets and other fabric surfaces, such as upholstery. Most carpet extractors comprise a fluid delivery system and a fluid recovery system. The fluid delivery system typically includes one or more fluid supply tanks for storing a supply of cleaning fluid, a fluid distributor for applying the cleaning fluid to the surface to be cleaned, and a fluid supply conduit for delivering the cleaning fluid from the fluid supply tank to the fluid distributor. The fluid recovery system usually comprises a recovery tank, a nozzle adjacent the surface to be cleaned and in fluid communication with the recovery tank through a conduit, and a source of suction in fluid communication with the conduit to draw the cleaning fluid from the surface to be cleaned and through the nozzle and the conduit to the recovery tank.

Portable extractors can be adapted to be hand-carried by a user. An example of a portable extractor is disclosed in commonly assigned U.S. Pat. No. 7,073,226 to Lenkiewicz et al., which is incorporated herein by reference in its entirety.

SUMMARY OF THE INVENTION

According to one aspect of the invention, a surface cleaning apparatus for cleaning a surface comprises a housing at least partially defining an air pathway, a fluid delivery system having a supply tank provided with the housing for storing cleaning fluid and a fluid distributor for delivering the cleaning fluid from the supply tank to the surface, a motor/fan assembly provided within the air pathway for generating an airflow through the pathway wherein the motor/fan assembly transfers heat to air moving through the pathway and removes heated air from the air pathway, the air pathway having an inlet upstream of the motor/fan assembly and an outlet downstream of the motor/fan assembly, and a duct downstream of the motor/fan assembly and upstream of the outlet and having a section in heat exchange relationship with the supply tank, with the section of the duct having an undulating profile providing an increased surface area in heat exchange relationship with the supply tank to heat the supply of cleaning fluid in the supply tank by heat transfer from the heated air.

DESCRIPTION OF EMBODIMENT(S) OF THE INVENTION

The invention relates to a surface cleaning apparatus that delivers cleaning fluid to a surface to be cleaned. In one of its aspects, the invention relates to a portable extraction cleaner that is adapted to be hand carried by a user to carpeted areas for cleaning relatively small areas and extracts cleaning fluid and debris from the surface.

FIG. 1is a front perspective view of a surface cleaning apparatus in the form of a portable extraction cleaner10according to a first embodiment of the invention. The portable extraction cleaner or “extractor”10includes a main housing assembly12selectively carrying a fluid delivery system14for storing cleaning fluid and delivering the cleaning fluid to the surface to be cleaned, and a fluid recovery system16for removing the cleaning fluid and debris from the surface to be cleaned and storing the recovered cleaning fluid and debris. The main housing assembly12is adapted to selectively mount components of the fluid delivery system14and the fluid recovery system16to form an easy-to-carry unit that can be transported by a user to different locations with surfaces to be cleaned. While the extractor10is illustrated as a portable extraction cleaner, aspects of the invention may be applicable to other types of surface cleaners, including upright extractors having a base assembly for movement across a surface to be cleaned and a handle assembly pivotally mounted to a rearward portion of the base assembly for directing the base assembly across the surface to be cleaned, and surface cleaners which have fluid delivery but not extraction capabilities.

The fluid delivery system14can include a fluid supply tank assembly18for storing a supply of cleaning fluid and a fluid distributor20provided on a hand-held accessory tool22in fluid communication with the supply tank assembly18for depositing a cleaning fluid onto the surface. Various combinations of optional components can be incorporated into the fluid delivery system14such as a conventional fluid pump, a heater, or fluid control and mixing valves as is commonly known in the art.

The fluid recovery system16can include an extraction path in the form of an extraction nozzle24provided on the accessory tool22which is adapted to be used on the surface to be cleaned, a recovery tank assembly26, and a flexible vacuum or suction hose28in fluid communication with the extraction nozzle24and the recovery tank assembly26.

The main housing assembly12comprises a base housing30and a partition housing32extending upwardly from the base housing30. In a preferred embodiment, main housing assembly12is formed of an opaque material, but can be formed of a translucent or transparent material. The partition housing32includes a carry handle34at an upper portion thereof which facilitates carrying the extractor10from one location to another. A button36can be provided adjacent the carry handle34and is operably coupled to one or more electrical components of the extractor10. A resilient boot seal37can be fastened to the recessed area beneath the carry handle34to form a flexible barrier that isolates the button36and internal electrical components from moisture ingress. The resilient boot seal37has been illustrated as being over molded onto the partition housing32for exemplary purposes; however, other fastening means are possible such as adhesive or mechanical fasteners, for example.

FIG. 2is a rear perspective view of the extractor10fromFIG. 1. The base housing30includes a skirt38having a suction hose rest40on one end thereof adapted to receive the suction hose28when it is wrapped around the skirt38for storage, as shown inFIG. 2. A tool retaining bracket42can extend from the partition housing32and is adapted to retain the accessory tool22attached to the suction hose28when the suction hose28is wrapped around the skirt38. A cord wrap caddy44can be provided on a side of the partition housing32for storing a power cord (not shown) which emerges from the interior of the partition housing32through a cord aperture46can be used to provide power to electrical components of the extraction cleaner10from a source of power, such as a home power supply, upon actuation of the button36. Alternatively, the extraction cleaner10can be powered by a portable power supply, such as a battery, upon actuation of the button.

An inlet48for a motor-cooling air pathway is provided in the base housing30and is illustrated as including a plurality of inlet openings50formed in the partition housing32between the tool retaining bracket42and the cord wrap caddy44. An outlet52for the motor-cooling air pathway is also provided in the base housing30and is illustrated as including a plurality of outlet openings54formed in the skirt38of the partition housing32, in the area underneath the supply tank assembly18. An inlet opening55for a pump-cooling air pathway is also provided in the base housing30and is also formed in the skirt38of the partition housing32, in the area underneath the supply tank assembly18. The pump-cooling air can be drawn in through the inlet opening55, into an electrical portion of the pump assembly176(FIG. 6) and can be exhausted through an exhaust fitting (not shown) and tube (not shown) that fluidly connect the pump-cooling air path to the extraction path, upstream from a suction source, such as a motor/fan assembly172.

FIG. 3is a partially-exploded view of the extractor10fromFIG. 1. The base housing30and partition housing32collectively define opposing tank receivers56,58for respectively receiving the supply tank assembly18and recovery tank assembly26. The supply tank receiver56includes a portion of the skirt38, a first side wall60of the partition housing32, and a first platform62defined between the skirt38and the partition housing32. The supply tank receiver56further includes a hanger64protruding from the first side wall60which is fitted into a corresponding socket66formed in the supply tank assembly18when the supply tank assembly18is seated within the supply tank receiver56. A valve seat68is formed in the first platform62for fluidly coupling with the supply tank assembly18when it is seated within the supply tank receiver56.

The first side wall60of the partition housing32further includes a semi-circular protrusion70having a top wall72and an arcuate side wall74. A vent76is formed in the first side wall60above top wall72by multiple openings, and a semi-circular air passage78is formed in the first platform62at the bottom end of the arcuate side wall74.

The recovery tank receiver58includes a portion of the skirt38, a second side wall80of the partition housing32, and a second platform82defined between the skirt38and the partition housing32. The recovery tank receiver58further includes a hanger84protruding from the second side wall80which is fitted into a corresponding socket86formed in the recovery tank assembly26when the recovery tank assembly26is seated within the recovery tank receiver58. A liquid port88and a suction port90are formed in the second platform82for fluidly coupling with the recovery tank assembly26when it is seated within the recovery tank receiver58.

The supply tank assembly18can include a supply tank92, a fill closure94, and a valve assembly96. The supply tank92can have a recessed lower portion98, a recessed upper portion100, and a peripheral side wall102joining the upper and lower portions98,100. The side wall102can include integrally molded handgrip indentations104, which facilitates removing and carrying the supply tank92. The supply tank92can be formed of a transparent or tinted translucent material, which permits a user to view the contents of the tank92.

The side wall102can include an externally-facing surface106, which forms an external surface of the extractor10when the supply tank92is seated in the supply tank receiver56and an internally-facing surface108, which is internal to the extractor10when the supply tank92is seated in supply tank receiver56. The handgrip indentations104can be formed in the externally-facing surface106and the socket66can be formed in the internally-facing surface108.

The recessed lower portion98can include a lower110surface adapted to rest on the first platform62of the base housing30and a hollow neck112protruding from the lower surface110that defines an outlet of the supply tank92which receives the valve assembly96. The valve assembly96is adapted to move to a closed position to seal the outlet of the supply tank92when the supply tank92is removed from the base housing30. When the supply tank92is seated in the supply tank receiver56, the neck112is at least partially received within the valve seat68and the valve assembly96is adapted to automatically move to an open position to open the outlet of the supply tank92.

The recovery tank assembly26can include a recovery tank114and an air/liquid separator assembly116. The recovery tank114can have a recessed lower portion118, a recessed upper portion120, and a side wall122joining the upper and lower portions118,120. The side wall122can include integrally molded handgrip indentations124, which facilitates removing and carrying the recovery tank114. The recovery tank114can be formed of a transparent or tinted translucent material, which permits a user to view the contents of the tank114.

The sidewall122can include an externally-facing surface126, which forms an external surface of the extractor10when the recovery tank114is seated in the recovery tank receiver58and an internally-facing surface128, which is internal to the extractor10when the recovery tank114is seated in recovery tank receiver58. The handgrip indentations124can be formed in the externally-facing surface126and the socket86can be formed in the internally-facing surface128. The recovery tank114can further include a closure129selectively closing an emptying port131in the recovery tank114. The closure129can be made from a flexible material, which permits easy assembly with the recovery tank114and easy opening and closing of the port131for emptying the recovery tank114.

The recessed lower portion118can include a lower surface130adapted to rest on the second platform82of the base housing30and neck132protruding from the lower surface130and defining an opening which receives the air/liquid separator assembly116.

The air/liquid separator assembly116comprises a riser tube134for guiding air and liquid through the recovery tank114, a sealing assembly136, and a float assembly138for selectively closing the suction path through the recovery tank114. The sealing assembly136provides a fluid-tight interface between the recovery tank assembly26and the liquid and suction ports88,90when the recovery tank assembly26is mounted within the recovery tank receiver58, and also prevents the recovery tank114from leaking when removed from the main housing assembly12.

The sealing assembly136includes a gasket140on the lower end of the riser tube134which mates with the liquid and suction ports88,90when the recovery tank114is mounted to the recovery tank receiver58, and a backflow preventer in the form of a duckbill valve142which prevents the escape of fluid drawn into the air/liquid separator assembly116from the recovery tank114. As a suction force is generated within the recovery tank114, the apex of the duckbill valve142separates to allow fluid to pass through the valve142. When this force is removed, the valve142is naturally biased closed and prevents backflow of liquid. An annular gasket144is provided for maintaining a fluid-tight interface between the lower end of the riser tube134and the recovery tank114when the riser tube134is mounted therein.

The float assembly138includes float shutter146and a float body148provided on the float shutter146for selectively raising the float shutter146to a closed position in which the float shutter146closes an air inlet port150of the riser tube134. The float shutter146slides within a guide passage152provided on the riser tube134, and is retained therein by opposing projections154, with the float body148facing away from the guide passage152. As the liquid level recovery tank114rises, the float body148raises the float shutter to close the air inlet port150to prevent liquid from entering the suction source of the extractor10.

FIG. 4is a partially-exploded view of the recovery tank assembly26. The air/liquid separator assembly116is configured to be easily removable from the recovery tank114by a user. This permits the recovery tank114to be emptied, and both the recovery tank114and the air/liquid separator assembly116to be disassembled and cleaned more thoroughly as needed. A mechanical coupling between the recovery tank114and the air/liquid separator assembly116can be provided for facilitating easy separation of the two components. As shown herein, the mechanical coupling comprises a bayonet interface156between the recovery tank114and the air/liquid separator assembly116.

The bayonet interface156includes one or more radial pins158provided on the neck132of the recovery tank114and one or more corresponding slots160provided on a rim162at the lower end of the riser tube134. As shown herein, three equally-spaced pins158are provided, and are generally rectangular in shape. Three equally-spaced corresponding slots160are also provided, and are generally configured to receive the pins158.

FIGS. 5A-Cillustrate a procedure for coupling the air/liquid separator assembly116and the recovery tank114via the bayonet interface156fromFIG. 4. The slots160each include a slot opening164provided on an upper side166of the rim162, and a closed slot passage168extending from the slot openings164underneath the upper side166. To couple the air/liquid separator assembly116to the recovery tank114, the pins158on the neck132are aligned with the slot openings164on the riser tube134, as shown inFIG. 5A. The air/liquid separator assembly116and the recovery tank114are then pushed together to seat the pins158in the slot openings164, as shown inFIG. 5B. The air/liquid separator assembly116and the recovery tank114are then rotated relative to each other so that the pins158slide into the slot passages168, as shown inFIG. 5C.

Variations of the bayonet interface156, such as of the shape of the pins/slots, the number of pins/slots, are possible while still maintaining an easy connection interface. To prevent misassembly by a user, the pins158and slots160can be positioned around the neck132and rim162in an irregular pattern to ensure that the air/liquid separator assembly116can be assembled to the recovery tank114in a single orientation only. Furthermore, the location of the pins158and slots160can be reversed, i.e. the pins158can be provided in the air/liquid separator assembly116and the slots160can be provided on the recovery tank114. Other types of mechanical couplings can also be used between the recovery tank114and the air/liquid separator assembly116, including, but not limited to, a threaded couplings, a keyed couplings, and other quick coupling mechanisms.

FIG. 6is a cross-sectional view of the extractor10through line VI-VI ofFIG. 1. The partition housing32can define one or more internal chambers for receiving components of the extractor10, including a suction source chamber170for receiving a suction source, such as a motor/fan assembly172and a pump chamber174for receiving the pump assembly176. The motor/fan assembly172can be considered part of the fluid recovery system16and is in fluid communication with the recovery tank assembly26and is configured to generate a working airflow to draw liquid and entrained debris through the accessory tool22and the suction hose28(FIG. 1). The motor/fan assembly172includes a suction motor178with an attached impeller assembly180having an impeller inlet182and at least one impeller outlet184. The pump assembly176can be considered part of the fluid supply system14and is in fluid communication with the supply tank assembly18and is configured to supply fluid from the supply tank assembly18to the accessory tool22(FIG. 1).

The riser tube134of the recovery tank assembly26has an internal divider186dividing the tube134into two fluidly isolated conduits, a liquid conduit188and an air conduit190. The liquid conduit188is open to the liquid port88in the base housing30and receives the duckbill valve142in the bottom end of the riser tube134. A liquid outlet port192of the liquid conduit188opens into the interior of the recovery tank114formed in the upper end of the riser tube134.

The air conduit190is open to the suction port90in the base housing30, and includes the air inlet port150formed in an upper end of the riser tube134. The air inlet port150is configured to be closed by the float shutter146as the liquid level in the recovery tank114rises to prevent liquid from entering the motor/fan assembly172.

A recovery inlet conduit194extends at least partially through the base housing30and fluidly communicates the recovery tank assembly26with the suction hose28via the liquid port88and the liquid conduit188. A recovery outlet conduit196also extends through the base housing30, and fluidly communicates the recovery tank assembly26with the impeller inlet182via the air conduit190and suction port90. An exhaust passage198is fluidly formed between the impeller outlet(s)184and an exhaust outlet200formed in a bottom wall202of the base housing30. The exhaust outlet200can include an exhaust grill having a plurality of openings (not shown).

As briefly mentioned above, a motor-cooling air pathway is provided in the extractor10for providing cooling air to the suction motor178and for removing heated cooling air (also referred to herein as “heated air”) from the suction motor178. The motor-cooling air pathway includes the inlet48, which is fluidly upstream of the suction motor178, and the outlet52, which is fluidly downstream of the suction motor178. Both the inlet48and the outlet52are in fluid communication with the ambient air outside the extractor10.

The suction motor178is enclosed within a motor cover204, which may be made of one or more separate pieces. The motor cover204includes at least one aperture206, shown herein as a plurality of apertures206, for allowing cooling air to enter the motor cover204and pass by the suction motor178. A heated air outlet conduit208can extend from the motor cover204for allowing heated air to be transported away from the suction motor178. A illustrated, the outlet conduit208has an inlet end210attached to the motor cover204, which juts outwardly to a vertical portion212joined at substantially a right-angle to the inlet end210. The vertical portion212of the outlet conduit208extends upwardly within the partition housing32to an outlet end214in fluid communication with the vent76. The outlet end214can be circuitous, and can include an internal air guide216which leads the heated air through at least a 180° turn into the vent76. The semi-circular protrusion70in the partition housing32can accommodate the outwardly-jutting outlet conduit208between the motor/fan assembly and the supply tank assembly18.

A portion of the motor-cooling air pathway downstream of the suction motor178can extend near the supply tank assembly18, such that cooling air heated by the suction motor178can be used to heat the fluid inside the supply tank92. As shown herein, a heat transfer duct218is formed downstream of the outlet conduit208between the semi-circular protrusion70of the partition housing32and the internally-facing surface108of the supply tank92, when the supply tank assembly18is seated on the base housing30. The heat transfer duct218can extend between the vent76and the air passage78formed in the first platform62. The air passage78can extend beneath the semi-circular protrusion70to the outlet52formed in the skirt38of the base housing30and can be at least partially defined by a duct220extending through the base housing.

FIG. 7is a perspective view of the fluid supply tank assembly18of the extractor10. The recessed upper portion100of the supply tank92includes an angled face222which has a fill opening224and a cap attachment aperture226formed therein. The fill closure94comprises a cap228which is selectively received in the fill opening224to seal the fill opening224, and an attachment plug230which is joined to the cap228by a tether232. The attachment plug230can be press-fit into the cap attachment aperture226to retain the fill closure94on the supply tank92, even when the cap228is removed from the fill opening224. A grip tab234can be provided on the cap228for facilitating removal of the cap228from the fill opening224. The fill closure94can be made from a flexible material, which permits easy assembly with the supply tank92and easy opening and closing of the fill opening224for filling or emptying the supply tank92.

The recessed lower portion98comprises a semi-circular peripheral wall236joining the lower surface110to the side wall102in the vicinity of the internally-facing surface108. The internally-facing surface108of the side wall102further includes a generally arcuate recessed section238that is defined by an upper surface240in which the socket66can be formed and a side surface242. The recessed section238is open at its bottom end, and opens to the space defined by semi-circular peripheral wall236of the recessed lower portion98.

FIG. 8is a cross-sectional view of the extractor10through line VIII-VIII ofFIG. 1. Heat is transferred to the fluid inside the supply tank92primarily through the side surface242to maintain or raise the temperature of the fluid. The side surface242can have a configuration or profile which allows heat to be transferred to the fluid inside the supply tank92. As illustrated herein, the side surface242has a wavy or undulating profile that includes a plurality of undulations244which define channels246extending vertically along the side surface242. The undulations244increase the effective surface area of the side surface242, and therefore increase the effective surface area of the heat transfer duct218, and thereby enhance heat transfer between the heated air in the heat transfer duct218and the fluid in the supply tank92. Other configurations/profiles for the side surface242are possible, including other patterns which increase the effective surface area of the side surface242. In an alternate embodiment, the side surface242can also be substantially smooth, i.e. without undulations244. In this embodiment, some heat is still transferred between the heated air and the fluid in the supply tank92, although not as much as when the effective surface area of the side surface242is increased using a non-smooth profile.

FIG. 9is a cross-sectional view similar toFIG. 6, illustrating the flow of motor-cooling air through the extractor10. In operation, the extractor10can be used to treat a surface to be cleaned by alternately applying a cleaning fluid to the surface from the supply tank assembly18and extracting the cleaning fluid from the surface into the recovery tank assembly26. When power is applied to the suction motor178, it drives the impeller assembly180to generate a suction force in the recovery tank114and in the recovery inlet conduit194coupled with the suction hose28and accessory tool22(FIG. 1). Suction force at the extraction nozzle24of the accessory tool22draws debris-containing fluid, which can contain air and liquid into the recovery tank114, via the open duckbill valve142and the liquid conduit188of the riser tube134. Liquid and debris in the fluid fall under the force of gravity to the bottom of the recovery tank114. The air drawn into the recovery tank114, now separated from liquid and debris, is drawn into the air conduit190, and passes through the impeller inlet182via the recovery outlet conduit196. The air passes through the impeller assembly180and through the impeller outlet(s)184to the exhaust passage198, whereupon the air exits the extractor10through the exhaust outlet200.

During operation of the suction motor178, ambient cooling air enters the suction source chamber170through the inlet48, and passes into the motor cover204via the apertures206, as indicated by arrow A. As the cooling air passes the suction motor178, heat from the suction motor178is transferred to the cooling air, thereby cooling the suction motor178and heating the cooling air. The heated cooling air (“heated air”) exits the motor cover204via the outlet conduit208, which directs the heated air into the heat transfer duct218via the vent76, as indicated by arrow B. While in the heat transfer duct218, heat from the heated air is transferred to the fluid inside the supply tank92through the side surface242. As the heated air passes through the heat transfer duct, and heat is transferred to the supply tank92, the heated air will cool. The cooled air can have the same temperature as the ambient cooling air drawn in through the inlet48, or may be slightly warmer or cooler. The cooled air will then pass into the air passage78, as indicated by arrow C, and exit the extractor10through the outlet52.

FIG. 10is a graph illustrating the temperature of fluid within the supply tank assembly during operation of the portable extraction cleaner. In the graph, data for two different embodiments of the portable extraction cleaner are compared. Line X represents the data for the extractor10shown inFIGS. 1-9, which has the heat transfer duct218formed in part by the supply tank92having the plurality of undulations244which define the vertical channels246. Line Y represents an extractor similar to the extractor shown inFIGS. 1-9, with the exception that the extractor was provided with a separate exhaust duct (not shown) that was configured to divert heated motor cooling air away from the heat transfer duct218and side surface242of the fluid supply tank assembly18, rather than allowing the heated motor cooling air into the heat transfer duct218. Instead, the separate exhaust duct of the Line Y extractor was configured to guide heated motor cooling air out of the main housing12and into ambient surrounding air outside the extractor10so as to not impart heat from the heated motor cooling air to the fluid within the supply tank assembly18.

To compare the extractors, both extractors were operated until the supply tank92was empty by repeatedly applying two equal fluid dispensing strokes using the fluid distributor20on the tool22and two equal fluid extraction strokes using the extraction nozzle24on the tool24. The graph ofFIG. 10shows a moving average (period=15) of the data obtained during the test. For the extractor10shown inFIGS. 1-9(Line X) configured heat the fluid inside the supply tank assembly18by heat transfer, the temperature of the fluid within the supply tank92at the beginning of operation, i.e. operation time=0, was approximately 31.6° C. (88.9° F.). For the extractor represented by Line Y, the temperature of the fluid within the supply tank92at the beginning of operation was approximately 31.9° C. (89.4° F.). The temperature was monitored near the valve assembly96of the supply tank assembly18while the extractors were operated.

As can be seen from the graph, for the extractor10shown inFIGS. 1-9and represented by Line X, the temperature of fluid within the supply tank92increased with operation time. This is attributed to the heat transfer between the heated air within the heat transfer duct218and the fluid in the supply tank92. Also, the temperature increase was more pronounced the longer the extractor10was operated. Conversely, for the extractor represented by Line Y, which was configured to divert the heated air away from the heat transfer duct218, the temperature of the fluid within the supply tank92did not increase and eventually dropped slightly near the end of the operation time. As shown inFIG. 10, the temperature increase was several degrees for the first embodiment (Line X), reaching a high of approximately 35° C. near seven minutes of operation time. The temperature increase seen in Line X and not line Y is attributable to heat transfer from the heated motor-cooling air in the heat transfer duct218to the supply tank92. Moreover, increasing the effective surface area of the heat transfer duct218by incorporating undulations244and vertical channels246on the first sidewall60further enhances heat transfer between the heated air in the heat transfer duct218and the fluid in the supply tank92.

FIG. 11is a cross-sectional view of a portable extraction cleaner10according to a second embodiment of the invention, in which like elements are referred to with the same referenced numerals used for the first embodiment. In the second embodiment, the heat transfer duct218with the undulating profile can be used to transfer heated exhaust air, instead of or in addition to heated motor cooling air, past the supply tank92. In this configuration, the impeller outlet(s)184are in fluid communication with an inlet to the heat transfer duct218, rather than exhaust outlet200, which can be eliminated. The exhaust passage198in this case is fluidly formed between the impeller outlet(s)184and the heat transfer duct218.

In operation, when power is applied to the suction motor178, the suction motor178drives the impeller assembly180to generate a suction force in the recovery tank114and in the recovery inlet conduit194coupled with the suction hose28and accessory tool22. The air drawn into the recovery tank114, separated from liquid and debris, is drawn into the air conduit190, and passes through the impeller inlet182via the recovery outlet conduit196. The air is heated by compression within the impeller assembly180and friction against the blades of the impeller. There may also be some heat transfer to the air from the suction motor178. The air passes through the impeller assembly180and through the impeller outlet(s)184to the heat transfer duct218. While in the heat transfer duct218, heat from the heated exhaust air is transferred to the fluid inside the supply tank92through the side surface242. Increasing the effective surface area of the heat transfer duct218by incorporating the undulations244and vertical channels246enhance heat transfer between the heated exhaust air in the heat transfer duct218and the fluid in the supply tank92. As the heated exhaust air passes through the heat transfer duct, and heat is transferred to the supply tank92, the heated exhaust air will cool. The cooled exhaust air can have the same temperature as the ambient air drawn in through the accessory tool22, or may be slightly warmer or cooler. The cooled exhaust air will then pass into the air passage78, and exit the extractor10through the outlet52as indicated by arrow C.

In this embodiment, the motor-cooling air pathway can be isolated from the exhaust air pathway, including the heat transfer duct218. During operation of the suction motor178, ambient cooling air enters the suction source chamber170through the inlet48, and passes into the motor cover204via the apertures206, as indicated by arrow A. The cooling air exits the motor cover204and can be directed out of the extractor10via an outlet (not shown). Alternatively, a separate heat transfer duct (not shown) can be provided for directing the heated motor cooling air past the supply tank92. Thus, the fluid inside the supply tank92can be heated by both heated exhaust air and heated motor cooling air.

The disclosed embodiments are representative of preferred forms of the invention and are intended to be illustrative rather than definitive of the invention. The illustrated upright extractor is but one example of the variety of deep cleaners with which this invention or some slight variant can be used. Reasonable variation and modification are possible within the forgoing disclosure and drawings without departing from the scope of the invention which is defined by the appended claims.