SURFACE CLEANER

Abstract

A surface cleaner operable to clean a surface. The surface cleaner includes a housing having a handle and a base pivotably coupled to the handle, the handle configured to move the base along the surface. The surface cleaner includes a supply tank configured to store a liquid, a heater including a reservoir, a pump positioned between the supply tank and the heater, the pump operable to draw the liquid from the supply tank and pump the liquid into the reservoir, the heater operable to superheat the liquid. The surface cleaner also includes a pressure control element in fluid communication with the heater and operable to depressurize the liquid into vapor, a nozzle disposed in the base and in fluid communication with the pressure control element, the nozzle configured to dispense the vapor, and a cleaning pad coupled to the base such that the cleaning pad directly contacts the surface.

Description

BACKGROUND

The present disclosure relates to surface cleaners.

Surface cleaners, such as steam mops, typically include a supply tank configured to store a liquid. The steam mop typically includes an electric heater that is operable to heat the liquid to produce hot water or steam, which is dispensed from a nozzle of the steam mop and onto a surface to be cleaned. The steam mop may also include a scrubbing pad or the like that is moved along the surface by the user to facilitate removing dirt and debris from the surface.

SUMMARY

In one aspect, the disclosure provides a surface cleaner operable to clean a surface. The surface cleaner includes a housing having a handle and a base pivotably coupled to the handle, the handle configured to move the base along the surface. The surface cleaner includes a supply tank configured to store a liquid, a heater including a reservoir, a pump positioned between the supply tank and the heater, the pump operable to draw the liquid from the supply tank and pump the liquid into the reservoir, the heater operable to superheat the liquid. The surface cleaner also includes a pressure control element in fluid communication with the heater and operable to depressurize the liquid into vapor, a nozzle disposed in the base and in fluid communication with the pressure control element, the nozzle configured to dispense the vapor, and a cleaning pad coupled to the base such that the cleaning pad directly contacts the surface.

In another aspect, the disclosure provides a method of operating a surface cleaner comprising pumping a liquid from a supply tank into a reservoir of a heater using a pump, pressurizing the liquid in the reservoir using the pump to a pressure greater than atmospheric pressure, powering the heater using power from an onboard battery. The method also includes superheating the liquid in the reservoir under the pressure to a predetermined temperature, depressurizing the liquid using a pressure control element to form vapor, and discharging the vapor through a nozzle.

Other aspects of the disclosure will become apparent by consideration of the detailed description and accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a surface cleaner.

FIG. 2 is a bottom side view of a base of the surface cleaner of FIG. 1.

FIG. 3 is a bottom side view of a base of the surface cleaner of FIG. 1 including a cleaning pad.

FIG. 4 is top perspective view of a cleaning pad coupled to a base of the surface cleaner of FIG. 1.

FIG. 5 is a schematic view of the surface cleaner of FIG. 1.

FIG. 6 is a schematic view of a control scheme for a controller for use with the surface cleaner of FIG. 1.

Before any embodiments of the disclosure are explained in detail, it is to be understood that the disclosure is not limited in its application to the details of construction and the arrangement of components set forth in the following description or illustrated in the following drawings. The disclosure is capable of other embodiments and of being practiced or of being carried out in various ways. Also, it is to be understood that the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting.

DETAILED DESCRIPTION

FIG. 1 illustrates a device, such as a surface cleaner 10 operable to clean a surface. The surface cleaner 10 includes a housing 18. In the illustrated embodiment, the housing 18 includes a handle 14 and a base 22 pivotally coupled to the handle 14 forming an upright configuration. The handle 14 is coupled to the housing 18 such that the handle 14 pivots with respect to the base 22. In other embodiments, the housing 18 is arranged in a handheld configuration, or a robotic surface cleaning configuration, or a canister style configuration, or other vapor cleaning arrangements. In other embodiments, the device is a garment steamer, floor cleaner, or countertop cleaner. Still, in other embodiments, the device is not an upright surface cleaner.

A battery 26 for supplying power to the surface cleaner 10 is disposed within the housing 18. The battery 26 is onboard the surface cleaner 10. The battery 26 includes an interface 30 or the battery 26 is in electrical communication with the interface 30 configured to be connected to an external power source (e.g., a charging station or an external power source such as an AC power wall outlet) to charge the battery 26. In some embodiments, the battery 26 is removable from the housing 18 for charging.

As shown in FIGS. 2 and 3, the base 22 includes a nozzle 34 for dispensing vapor. In one example, steam is generated when water achieves a temperature of 100 degrees Celsius or more. In the illustrated embodiment, a cleaning pad 38 is removably coupled to the base 22 such that the cleaning pad 38 contacts the surface to be cleaned (FIGS. 3 and 4). In one embodiment, the cleaning pad 38 includes at least one aperture 42 adjacent the nozzle 34 to allow vapor to flow from the nozzle 34, through the aperture 42, toward the surface. In some embodiments, the cleaning pad 38 may include multiple apertures 42 having different sizes, shapes, and positions on the cleaning pad 38 as appropriate (e.g., circular apertures having varying diameters, polygonal apertures having varying dimensions, or the like). In another embodiment, the nozzle directs the vapor adjacent to the cleaning pad 38. In yet another embodiment, the nozzle directs the vapor onto or toward the cleaning pad 38. In some embodiments, such as in a handheld configuration, the nozzle 34 may be disposed in or adjacent a cleaning tool or accessory, or at a distal end of a wand, for example.

FIG. 5 schematically illustrates the components of the surface cleaner 10 positioned within the housing 18. The surface cleaner 10 includes a supply tank 46, a heater 50 having a reservoir 70, the battery 26 for powering the heater 50, a pump 54, and a pressure control element 58. In other embodiments, the supply tank 46, the heater 50 having the reservoir 70, the battery 26 for powering the heater 50, the pump 54, and the pressure control element 58 are part of a steam generating device or steam generator. A conduit 62 fluidly connects the supply tank 46, the heater 50, and the pressure control element 58 together, and extends to the nozzle 34. In one embodiment, the nozzle 34 is disposed downstream of the pressure control element 58. In one embodiment, the pressure control element 58 is the nozzle 34. In another embodiment, the pressure control element 58 is incorporated into the nozzle 34. The supply tank 46 is configured to store a liquid, a fluid, water, a cleaning solution, or a mixture of water and cleaning solution. In some embodiments, the supply tank 46 is removably coupled to the housing 18 such that the supply tank 46 may be removed and re-filled with liquid. In other embodiments, the housing 18 includes a port 66 through which liquid may be poured to re-fill the supply tank 46 (FIG. 1).

In the illustrated embodiment, the pressure control element 58 is a pressure relief valve, or a spring-loaded poppet valve. In other embodiments, the pressure control element 58 is a flow restrictor operable to control the liquid at a desired flow rate. The pressure control element 58 is configured to maintain the pressure upstream of the pressure control element 58 at a predetermined pressure. In the illustrated embodiment, the pressure control element 58 includes a spring-loaded poppet valve having spring parameters configured to enable flow at a desired flow rate when the upstream pressure reaches the predetermined pressure. In one embodiment, the predetermined pressure is greater than 1 bar. In another embodiment, the predetermined pressure is between 1.2 and 3 bar. In another embodiment, the predetermined pressure is between 1.5 and 2 bar. In yet another embodiment, the predetermined pressure is between 1.25 and 1.8 bar. In one alternative, the pressure control element 58 includes an orifice operable to depressurize the superheated liquid in the reservoir 70 into vapor. In one embodiment, the pressure control element 58 is a flow restrictor or orifice having an aperture with a diameter sized to maintain the predetermined pressure. In one embodiment, the orifice is integrated into the nozzle 34.

With continued reference to FIG. 5, the heater 50 is operable to heat the liquid while the liquid is at the predetermined pressure thereby raising the temperature of the liquid to a predetermined temperature. In particular, the predetermined temperature is a temperature greater than a boiling temperature of the liquid at atmospheric pressure (the atmospheric boiling point). A liquid phase is maintained in the reservoir by heating under pressure. In other words, the heater 50 is controlled to heat the liquid in the pressurized environment above the atmospheric boiling point without completing a phase change (e.g., change from liquid to gas). The predetermined temperature above the atmospheric boiling point and the predetermined pressure are selected to be in the liquid phase of the liquid being heated. In one embodiment, the predetermined temperature above the atmospheric boiling point is greater than corresponding to a liquid phase at the predetermined pressure thereby providing a mixture of liquid and vapor in the heater.

The heater 50 includes a reservoir 70 having an inlet and an outlet along the conduit 62 configured to contain a desired volume of the liquid when the heater 50 is heating the liquid passing through the reservoir 70. The volume of the reservoir 70 is selected as a function of the desired flow rate and the capacity of the heater 50 to maintain the predetermined temperature by the heater 50 at the desired flow rate passing through the reservoir 70. In one embodiment, the reservoir 70 is a tubular shaped reservoir. In some embodiments, the reservoir 70 includes a serpentine flow path. In another embodiment, the reservoir 70 includes a chamber. In one embodiment, the heater 50 and/or reservoir 70 is insulated to aid in maintaining liquid temperature and to inhibit heat transfer to the battery 26, other components of the surface cleaner 10, and/or the exterior of the housing 18.

The heater 50 is in electrical communication with the battery 26 such that the heater 50 receives power from the battery 26 during operation. The heater 50 heats the liquid in the reservoir 70 to the predetermined temperature at the predetermined pressure. In one embodiment, the predetermined temperature is between 10 and 45 degrees Celsius above the atmospheric boiling point of the liquid. In one embodiment, the predetermined temperature is between 15 and 30 degrees Celsius above the atmospheric boiling point of the liquid. The liquid in the reservoir 70 is pressurized above atmospheric pressure. In yet another embodiment, the predetermined temperature is between 20 to 50 degrees Celsius above the atmospheric pressure. As a result of heating the liquid under such pressurization, the liquid in the reservoir 70 is a superheated liquid. In one embodiment, the liquid in the reservoir 70 is heated to a temperature of approximately 120 degrees Celsius at a pressure of approximately 2 bar. In one embodiment, the liquid in the reservoir 70 is heated to a temperature of between approximately 125 degrees and 145 degrees Celsius at a pressure of approximately 2 bar. In this embodiment, a mixture of liquid and vapor are in the reservoir 70.

With continued reference to FIG. 5, the pump 54 is positioned between the supply tank 46 and the heater 50. The pump 54 is in fluid communication with the supply tank 46, the reservoir 70 of the heater 50, and the conduit 62. The pump 54 is also in electrical communication with the battery 26, which powers the pump 54 to draw liquid from the supply tank 46, through the conduit 62, and into the reservoir 70 of the heater 50. The pump 54 is operable to deliver liquid from the supply tank 46 to the reservoir 70 and pressurize the reservoir 70 against the backpressure of the pressure control element 58 to the predetermined pressure to pass liquid through the pressure control element 58 at the desired flow rate. In one embodiment, the flow rate of liquid through the pump 54 and thereby through the reservoir 70 and pressure control element 58 is between 15 ml/min and 50 ml/min. In one embodiment, the flow rate of liquid through the pump 54 is between 15 ml/min and 30 ml/min. In the illustrated embodiment, the flow rate of liquid through the pump 54 is approximately 20 ml/min. In the illustrated embodiment, the conduit 62 includes a fluid line 86 for drawing liquid from the supply tank 46 to the pump 54, and a fluid line 84 for communicating liquid from the pump 54 to the reservoir 70.

As shown schematically in FIG. 5, the pressure control element 58 is in fluid communication with the reservoir 70 and the nozzle 34. The pressure control element 58 is operable to depressurize the superheated liquid in the reservoir 70 into vapor. In other embodiments, the heater 50 including the superheated liquid in the reservoir 70 and the pressure control element 58 are part of a steam generating device or steam generator that utilizes the pressure control element 58 to depressurize the superheated liquid in the reservoir 70 into steam. As the superheated liquid exits the pressure control element 58, the liquid depressurizes from the predetermined pressure to atmospheric pressure expanding the liquid into vapor. The expansion of the superheated liquid through the pressure control element 58 causes a temperature decrease in the liquid. In some embodiments, the predetermined pressure and predetermined temperature are selected such that the temperature of the liquid after the temperature decrease caused by expansion though the pressure control element 58 provides vapor at a temperature greater than 100 degrees C. In some embodiments, the liquid exiting the pressure control element 58 is a vapor at a temperature less than 100 degrees C. due to the temperature drop caused by expansion. In the illustrated embodiment, the conduit 62 further includes a fluid line 92 for transporting the superheated liquid from the reservoir 70 to the pressure control element 58 and a fluid line 90 for transporting the vapor from the pressure control element 58 to the nozzle 34. In other embodiments, the pressure control element 58 is mounted directly to the reservoir 70 (i.e., fluid line 92 is removed) such that the fluid line 90 transports the vapor from the pressure control element 58 to the nozzle 34. During operation, vapor passes from the pressure control element 58, through the fluid line 90 of the conduit 62, and is dispensed from the nozzle 34. It is understood that the temperature of the liquid drops as it travels through the fluid line 90 and the nozzle 34 and in many embodiments the liquid will be a vapor at a temperature less than 100 degrees C. exiting the surface cleaner 10.

With reference to FIG. 6, the surface cleaner 10 includes a controller 74 operable to control operation of the surface cleaner 10, and the components of the surface cleaner 10. In one embodiment, the controller 74 controls the pump 54 and the heater 50 providing a constant voltage or constant power to the components as the charge of the battery 26 decreases. In this embodiment, the parameters of the pump 54, heater 50, and pressure control element 58 are selected to provide the predetermined temperature at the predetermined pressure for a given liquid in steady state operation. In some embodiments, the controller 74 increases and decreases power to the pump 54 and the heater 50 to maintain the predetermined temperature and predetermined pressure as the charge of the battery 26 decreases. In this embodiment, the pump 54 and/or the heater 50 are variable in output and the controller 74 increases and decreases power to maintain the desired temperature and pressure. In one embodiment, the controller 74 utilizes pulse width modulation (i.e., PWM) to control operation of the components of the surface cleaner 10 such as the pump 54 and the heater 50. The controller 74 is in electrical communication with the battery 26, the pump 54, and the heater 50. The controller 74 is operable to control operation of the components of the surface cleaner 10 including the battery 26, the pump 54, and the heater 50. For example, the controller 74 is operable to increase and decrease power or activate and deactivate the pump 54 and/or the heater 50. The controller 74 monitors a pressure and a temperature of the liquid in the reservoir 70 to achieve the desired settings for the surface cleaner 10.

The heater 50 receives power from the battery 26 to maintain the liquid in the reservoir 70 at the predetermined temperature. In some embodiments, the heater 50 includes a temperature sensor 78 configured to measure a temperature of the liquid, where if the temperature of the liquid in the reservoir 70 decreases below the predetermined temperature, the controller 74 powers the heater 50 to re-heat the liquid. The controller 74 is operable to increase and decrease power to or activate and deactivate the heater based on a signal from the temperature sensor 78.

In one embodiment shown in FIGS. 5 and 6, the pump 54 and/or reservoir 70 includes a pressure sensor 82 to measure a pressure of the reservoir 70, and the controller 74 is operable to increase and decrease power to the pump 54 based on a signal from the pressure sensor 82 to maintain the predetermined pressure. In some embodiments, the controller 74 is operable to increase and decrease power to the pump 54 based on signal from the temperature sensor 78. Still, in some embodiments, the controller 74 is operable to increase and decrease power to the heater 50 based on a signal from the pressure sensor 82.

In some embodiments, the surface cleaner 10 receives power from an external power source (e.g., charging station, docking station, or AC power wall outlet) to heat the liquid to a preheat temperature. In this embodiment, the surface cleaner 10 is operable to perform a preheating function when coupled to the external power source. The surface cleaner 10 may include a user interface that enables the user to turn on and turn off the preheating function. The surface cleaner 10 may include a liquid level sensor to detect if the liquid in the supply tank 46 is at a sufficient level to begin the preheating the function. If the liquid in the reservoir 70 is not at a sufficient level for the preheating function, then the surface cleaner 10 provides a notification (e.g., light indicator or sound indicator) that the supply tank 46 needs to be re-filled. Once the liquid in the reservoir 70 is filled at the sufficient level and the surface cleaner 10 is connected to the external power source, the surface cleaner 10 begins the preheating function.

In this embodiment, a preheat heater 88 is provided in the supply tank 46. The preheating function includes using the controller 74 to activate the preheat heater 88 to heat the liquid to a preheat temperature between 5 and 30 degrees Celsius lower than the atmospheric boiling point. In one embodiment, the preheat temperature is between 5 and 10 degrees Celsius lower than the atmospheric boiling point. In another embodiment, the preheat temperature is between 5 to 15 degrees Celsius lower than the atmospheric boiling point. In one embodiment where the preheat heater 88 receives power from the external power source to heat the liquid to the preheat temperature, the preheat heater 88 receives power from the battery 26 to maintain the liquid in supply tank 46 at the preheat temperature when disconnected from the external power source. In one embodiment, the controller 74 will disable the preheat heater 88 when the battery 26 capacity depletes to a predetermined threshold when disconnected from the external power source. In another embodiment, the preheating function includes using the controller 74 to activate the heater 50 to preheat the heater 50 and reservoir 70.

In some embodiments, the surface cleaner 10 is connectable (or couplable) to the external power source (e.g., charging station, power cord plugged into wall outlet) to charge the battery 26. When a user wishes to use the surface cleaner 10 to clean a surface, the user may disconnect the surface cleaner 10 from the external power source and transport the surface cleaner 10. When the base 22 including the nozzle 34 is positioned on a surface to which vapor will be applied, the user engages a trigger, an actuator, a button 94 disposed on the handle 14. The pump 54 draws liquid from the supply tank 46, through the fluid line 86 of the conduit 62, and into the reservoir 70 of the heater 50 at a pressure to overcome the predetermined pressure of the pressure control element 58. The heater 50 heats the liquid to a predetermined temperature at the predetermined pressure by using power from the battery 26. The battery 26 powers the heater 50 to heat the liquid flowing through the reservoir 70 to predetermined temperature under pressure. As the liquid exits the pressure control element 58 it is depressurized causing expansion of the superheated liquid into vapor. The vapor is transported through the fluid line 90 of the conduit 62 to discharge through the nozzle 34.

The surface cleaner 10 utilizes the power from the battery 26 to heat the liquid in the reservoir 70. By keeping the liquid in the reservoir 70 in its liquid phase the amount of energy required to heat the liquid is less than the energy required to boil the liquid. For example, for water, the energy required to increase the temperature 20 degrees C. above the atmospheric boiling point as a liquid is approximately 450 KJ/kg, where the energy required to boil the water is approximately 2725 KJ/kg. Instead of converting the liquid into vapor in the reservoir 70, the liquid is maintained as a superheated liquid (i.e., liquid is in the liquid state at the predetermined temperature greater than the atmospheric boiling point) and discharged through the pressure control element 58 to expand into vapor. Utilizing a superheated liquid at the desired flow rate reduces the amount of energy required to produce vapor permitting the use of the battery 26, instead of requiring an external power source to operate the surface cleaner 10. In one embodiment, the heater 50 uses between 110 and 375 Watts of power to produce vapor. In another embodiment, the heater 50 uses between 125 and 300 Watts of power to produce vapor. In one embodiment, the heater 50 uses between 110 and 225 Watts of power to produce vapor. In one embodiment, the heater 50 uses less than 250 Watts of power to produce vapor. The surface cleaner 10 generates and applies vapor to the surface without being plugged into the external power source during use (i.e., the surface cleaner 10 is cordless during use). Further, although the liquid is heated in the reservoir 70, the liquid remains in its liquid state while under pressure in the reservoir 70 (i.e., the liquid does not complete a phase change in the reservoir 70 or minimal vapor exists in the reservoir 70 based on the vapor pressure of the liquid), and depressurization of the liquid occurs as the liquid exits the pressure control element 58.

In some embodiments, the battery 26 has a battery capacity of between 60 and 80 watt-hours. In some embodiments, the battery 26 has a battery capacity of between 120 and 160 watt hours. In one embodiment, the battery 26 is configured to provide about 20 volts and has a battery capacity of 72 watt hours. In one embodiment, the battery 26 is configured to provide about 20 volts and has a battery capacity of 144 watt hours.

In other embodiments, when an external power source (e.g., battery charging station or power cord coupled to an AC power wall outlet) is coupled to the surface cleaner 10 to charge the battery 26. In some embodiments, the surface cleaner 10 is operable to perform a preheating function when the surface cleaner 10 is coupled to the external power source. In one embodiment, the external power source is used to provide power to components of the surface cleaner 10 to operate the preheating function. The external power source powers the preheat heater 88 to heat the liquid in the supply tank 46 to the preheat temperature. The connection to the external power source reduces the energy required from the battery 26 to heat the liquid when the cleaner is disconnected from the external power source. The external power source may maintain the liquid at the preheat temperature until the cleaner is disconnected from the external power source.

In some embodiments, the preheating function includes using the controller 74 to activate the preheat heater 88 to heat the liquid in the supply tank 46 to a preheat temperature of approximately 5 to 30 degrees Celsius lower than the atmospheric boiling point when the surface cleaner 10 is coupled to the external power source. In one embodiment, the preheating function heats the liquid to a temperature of approximately 10 degrees lower than the atmospheric boiling point when the surface cleaner 10 is coupled to the external power source.

Thus, the disclosure provides, among other things, a surface cleaner. Although the disclosure has been described in detail with reference to certain preferred embodiments, variations and modifications exist within the scope and spirit of one or more independent aspects of the disclosure as described.

Various features and advantages of the disclosure are set forth in the following claims.

Claims

1. A surface cleaner operable to clean a surface, the surface cleaner comprising: a housing including a handle and a base pivotably coupled to the handle, the handle configured to move the base along the surface;a supply tank configured to store a liquid;a heater including a reservoir;a pump positioned between the supply tank and the heater, the pump operable to draw the liquid from the supply tank and pump the liquid into the reservoir, the heater operable to superheat the liquid;a pressure control element in fluid communication with the heater and operable to depressurize the liquid into vapor;a nozzle disposed in the base and in fluid communication with the pressure control element, the nozzle configured to dispense the vapor; anda cleaning pad coupled to the base such that the cleaning pad directly contacts the surface.

2. The surface cleaner of claim 1, further comprising: a battery operable to power the surface cleaner; anda controller configured to control operation of the surface cleaner.

3. The surface cleaner of claim 1, further comprising a conduit including a first fluid line extending between the supply tank the reservoir, and a second fluid line extending between the pressure control element and the nozzle.

4. The surface cleaner of claim 2, wherein the heater uses less than 250 Watts of power to heat the liquid.

5. The surface cleaner of claim 2, wherein the surface cleaner includes a first sensor configured to measure a pressure of the liquid, and wherein the surface cleaner includes a second sensor configured to measure a temperature of the liquid.

6. The surface cleaner of claim 5, wherein the controller is operable to activate and deactivate the pump based at least in part on a signal received from the first sensor or second sensor.

7. The surface cleaner of claim 5, wherein the controller is operable to activate and deactivate the heater based at least in part on a signal from the first sensor or second sensor.

8. The surface cleaner of claim 1, wherein the liquid is heated to a temperature of approximately 10 to 50 degrees above a boiling temperature of the liquid at atmospheric pressure.

9. The surface cleaner of claim 1, wherein the liquid is pressurized at a pressure ranging from 1 bar to 3 bar in the reservoir.

10. The surface cleaner of claim 2, wherein the surface cleaner is couplable to an external power source, the surface cleaner is operable to pre heat the liquid when coupled to the external power source.

11. The surface cleaner of claim 10, wherein the controller pre heats the liquid to a temperature approximately 10 degrees lower than a boiling temperature of the liquid at atmospheric pressure when coupled to the external power source.

12. The surface cleaner of claim 11, wherein the external power source is a battery charging station, the battery charging station is operable to pre heat the liquid when coupled to the battery charging station.

13. The surface cleaner of claim 11, further comprising a power cord couplable to the external power source to charge the battery when the surface cleaner is connected to the external power source.

14. The surface cleaner of claim 1, wherein the pump is operable to pressurize the liquid to a predetermined pressure greater than atmospheric pressure.

15. The surface cleaner of claim 1, wherein the cleaning pad includes at least one aperture that allows the vapor to flow from the nozzle, through the at least one aperture, and onto the surface.

16. A method of operating a surface cleaner comprising: pumping a liquid from a supply tank into a reservoir of a heater using a pump;pressurizing the liquid in the reservoir using the pump to a pressure greater than atmospheric pressure;powering the heater using power from an onboard battery;superheating the liquid in the reservoir under the pressure to a predetermined temperature;depressurizing the liquid using a pressure control element to form vapor; anddischarging the vapor through a nozzle.

17. The method of claim 16, further comprising controlling the heater using a controller.

18. The method of claim 17, further comprising powering the pump using power from the battery and controlling the pump using the controller.

19. The method of claim 17, further comprising a power cord couplable to an external power source to charge the battery when the surface cleaner is connected to the external power source.

20. The method of claim 19, further comprising preheating the liquid when coupled to the external power source, wherein preheating includes using the controller to activate the heater to heat the liquid to the predetermined temperature of approximately 10 degrees lower than a boiling temperature of the liquid at atmospheric pressure.

21. The method of claim 19, further comprising preheating the liquid when coupled to the external power source, wherein preheating includes using the controller to activate the heater to superheat the liquid in the reservoir under the pressure.

22. The method of claim 16, wherein the pressure ranges from 1 bar to 3 bar in the reservoir.

23. The method of claim 16, wherein the predetermined temperature is approximately 10 to 50 degrees Celsius above a boiling temperature of the liquid at atmospheric pressure.