Patent Application
20070283728
In the drawings:
To address the problems of scales and sludge, the invention provides methods and structures for preventing formation of and/or removing scale and sludge from a steam generator of a fabric treatment appliance. The fabric treatment appliance can be any machine that treats fabrics, and examples of the fabric treatment appliance include, but are not limited to, a washing machine, including top-loading, front-loading, vertical axis, and horizontal axis washing machines; a dryer, such as a tumble dryer or a stationary dryer, including top-loading dryers and front-loading dryers; a combination washing machine and dryer; a tumbling or stationary refreshing machine; an extractor; a non-aqueous washing apparatus; and a revitalizing machine. For illustrative purposes, the invention will be described with respect to a washing machine, with it being understood that the invention can be adapted for use with any type of fabric treatment appliance having a steam generator.
Referring now to the figures,
Washing machines are typically categorized as either a vertical axis washing machine or a horizontal axis washing machine. As used herein, the “vertical axis” washing machine refers to a washing machine comprising a rotatable drum, perforate or imperforate, that holds fabric items and a fabric moving element, such as an agitator, impeller, nutator, and the like, that induces movement of the fabric items to impart mechanical energy to the fabric articles for cleaning action. In some vertical axis washing machines, the drum rotates about a vertical axis generally perpendicular to a surface that supports the washing machine. However, the rotational axis need not be vertical. The drum can rotate about an axis inclined relative to the vertical axis. As used herein, the “horizontal axis” washing machine refers to a washing machine having a rotatable drum, perforated or imperforate, that holds fabric items and washes the fabric items by the fabric items rubbing against one another as the drum rotates. In horizontal axis washing machines, the clothes are lifted by the rotating drum and then fall in response to gravity to form a tumbling action that imparts the mechanical energy to the fabric articles. In some horizontal axis washing machines, the drum rotates about a horizontal axis generally parallel to a surface that supports the washing machine. However, the rotational axis need not be horizontal. The drum can rotate about an axis inclined relative to the horizontal axis. Vertical axis and horizontal axis machines are best differentiated by the manner in which they impart mechanical energy to the fabric articles. The illustrated exemplary washing machine of
The motor 22 can rotate the drum 16 at various speeds in opposite rotational directions. In particular, the motor 22 can rotate the drum 16 at tumbling speeds wherein the fabric items in the drum 16 rotate with the drum 16 from a lowest location of the drum 16 towards a highest location of the drum 16, but fall back to the lowest location of the drum 16 before reaching the highest location of the drum 16. The rotation of the fabric items with the drum 16 can be facilitated by the baffles 20. Alternatively, the motor 22 can rotate the drum 16 at spin speeds wherein the fabric items rotate with the drum 16 without falling.
The washing machine 10 of
The exemplary washing machine 10 further includes a steam generation system. The steam generation system comprises a steam generator 60 that receives liquid from the liquid inlet 28 through a second supply conduit 62. A second inlet valve 64 controls flow of the liquid from the liquid inlet 28 and through the second supply conduit 62 to the steam generator 60. The second inlet valve 64 can be positioned in any suitable location between the liquid inlet 28 and the steam generator 60. A steam conduit 66 fluidly couples the steam generator 60 to a steam inlet 68, which introduces steam into the tub 14. The steam inlet 68 can couple with the tub 14 at any suitable location on the tub 14 and is shown as being coupled to a rear wall of the tub 14 in
The steam generator 60 can be any type of device that converts the liquid to steam. For example, the steam generator 60 can be a tank-type steam generator that stores a volume of liquid and heats the volume of liquid to convert the liquid to steam. Alternatively, the steam generator 60 can be an in-line steam generator that converts the liquid to steam as the liquid flows through the steam generator 60. The steam generator 60 can produce pressurized or non-pressurized steam.
In addition to producing steam, the steam generator 60, whether an in-line steam generator, a tank-type steam generator, or any other type of steam generator, can heat water to a temperature below a steam transformation temperature, whereby the steam generator 60 produces hot water. The hot water can be delivered to the tub 14 and/or drum 16 from the steam generator 60. The hot water can be used alone or can optionally mix with cold water in the tub 14 and/or drum 16. Using the steam generator to produce hot water can be useful when the steam generator 60 couples only with a cold water source at the liquid inlet 28.
The steam generator 60 can be coupled to the steam conduit 66 in any suitable manner. In the illustrated embodiment of
The steam generator 60 further comprises a heater body 76 and a heater 78 embedded in the heater body 76. The heater body 76 is made of a material capable of conducting heat. For example, the heater body 76 can be made of a metal, such as aluminum. The heater body 76 of the illustrated embodiment is shown as being integrally formed with the main body 70, but it is within the scope of the invention for the heater body 76 to be formed as a component separate from the main body 70. In the illustrated embodiment, the main body 70 can also be made of a heat conductive material, such as metal. As a result, heat generated by the heater 78 can conduct through the heater body 76 and the main body 70 to heat fluid in the steam generation chamber 74. The heater 78 can be any suitable type of heater, such as a resistive heater, configured to generate heat. A thermal fuse 80 can be positioned in series with the heater 78 to prevent overheating of the heater 78. Alternatively, the heater 78 can be located within the steam generation chamber 74 or in any other suitable location in the steam generator 60.
The steam generator 60 further includes a temperature sensor 82 that can sense a temperature of the steam generation chamber 74 or a temperature representative of the temperature of the steam generation chamber 74. The temperature sensor 82 of the illustrated embodiment is coupled to the heater body 76; however, it is within the scope of the invention to employ temperature sensors in other locations. For example, the temperature sensor 82 can be a probe-type sensor that extends through the inside surface 72 into the steam generation chamber 74. However, it has been found that the temperature of the heater body 76 is representative of the temperature of the steam generation chamber 74 in that there is a relationship between the two temperatures. The temperature sensor 82, the heater 78, and the second inlet valve 64 can be coupled to a controller 84, which can control the operation of heater 78 and the second inlet valve 64 in response to information received from the temperature sensor 82.
The liquid supply and recirculation system and the steam generator system can differ from the configuration shown in
The washing machine 10 can further comprise a machine controller coupled to various working components of the washing machine 10, such as the pump 44, the motor 22, the first and second inlet valves 34, 64, the detergent dispenser 32, and the steam generator 60 to control the operation of the washing machine 10. The machine controller can receive data from the working components and can provide commands, which can be based on the received data, to the working components to execute a desired operation of the washing machine 10.
The washing machine of
A method 100 of operating the washing machine 10 according to one embodiment of the invention is illustrated in the flow chart of
During the steam generation step 102, the steam generator 60 receives water and converts the water to steam, which is introduced into the tub 14 and/or drum 16. The steam generation step 102 can proceed in any suitable manner to accomplish the conversion of water to steam. An exemplary execution of the steam generation step 102, which can be employed with the steam generator 60 shown in
Referring now to
After the steam generation chamber 74 is sufficiently filled with water, the introduction of water ceases, and the heater 78 is turned on in step 112 to heat the water in the steam generation chamber 74. Waiting to turn the heater 78 on until the steam generation chamber 74 is sufficiently full ensures that there is enough water in the steam generation chamber 74 to prevent damage to the heater. However, it is within the scope of the invention to turn the heater 78 on while the water is being introduced in the step 110. The temperature sensor 82 monitors the temperature of the steam generation chamber 74, and the controller 84 evaluates whether the temperature of the steam generation chamber 74 has reached a steam generation temperature in step 114. The steam generation temperature depends on environmental conditions, such as the pressure of the environment. For example, for an atmospheric pressure of about 1 atm (760 mm Hg), the steam generation temperature is about 100° C. If the temperature of the steam generation chamber 74 has not yet reached the steam generation temperature, then the steam generation step 102 continues with the step 112 of heating the water in the steam generation chamber 74.
Conversely, if the temperature of the steam generation chamber 74 has reached the steam generation temperature, then the water converts to steam, and the steam generation step 102 proceeds to step 116 of introducing water into the steam generation chamber 74 to replenish the water converting to steam and leaving the steam generation chamber 74 for introduction into the tub 14 and/or the drum 16. With the illustrated embodiment of the steam generator 60 in
An exemplary duty cycle for the above example of a 0.25 liter per minute valve flow rate and 1300 watt steam generator comprises an “on” period (i.e., the second supply valve 64 is open) of about 1 second that alternates with an “off” period (i.e., the second supply valve 64 is closed) of about 9 seconds to achieve an average water dosing of about 30 g/min. The step 116 of setting the valve duty cycle is shown in a box having dashed lines because this step can be eliminated or altered depending, for example, on the type and number of valves controlling the introduction of water into the steam generation chamber 74.
While the water is introduced into the steam generation chamber 74 and converted to steam, the temperature sensor 82 monitors the temperature of the steam generation chamber 74, and the controller 84 evaluates whether the temperature of the steam generation chamber 74 has reached an overheat temperature in step 120. The overheat temperature is a predetermined temperature sufficiently high to potentially damage the heater 78 and the steam generator 60. As an example, the overheat temperature can be about 200° C. If the temperature of the steam generation chamber 74 reaches or exceeds the overheat temperature, then an overheat protection step 130, which is described below, can be executed. If the temperature remains below the overheat temperature, then the introduction of water and generation of steam continues until the steam generation step 102 is complete. The completion of the steam generation step 102 is evaluated in step 122. For example, the steam generation step 102 can be considered complete after a predetermined period of time has elapsed or once the fabric in the drum 16 reaches a predetermined temperature. If the steam generation step 102 is complete, the method 100 proceeds to the steam generator cleaning step 104.
The overheat protection step 130 reduces the temperature of the steam generation chamber 74 and thereby prevents damage to the steam generator 60, particularly the heater 78. An exemplary execution of the overheat protection step 130 is provided in the flow chart of
The temperature sensor 82 monitors the temperature of the steam generation chamber 74, and the controller 84 evaluates whether the temperature of the steam generation chamber 74 has decreased sufficiently in step 136. The amount of temperature decrease corresponds to a safe operating temperature for the steam generator 60 and can depend on the type and size of the steam generator 60. The introduction of water continues in the step 134 until it is has been determined in the step 136 that the temperature decrease is sufficient. If a predetermined time has elapsed without a sufficient decrease in temperature, the steam generator 60 can cease operation, and an alert can be communicated to the user. Otherwise, after the temperature has sufficiently decreased, the overheat protection step 130 continues by turning off the heater 78 in step 138 and returning to the steam generation step 102, such as to the step 116 of introducing water during steam generation.
Prior to returning to the steam generation step 102, the overheat protection step 130 can include a step 140 of resetting the duty cycle of the second supply valve 64. The duty cycle can be reset so that a larger amount of water is provided to the steam generation chamber 74 in a given time period to thereby avoid overheating the steam generator 60 due to excessive reduction of the water in the steam generation chamber 74. For example, the above exemplary duty cycle can be reset by increasing the “on” period by 0.25 seconds and reducing the “off” period by 0.25 seconds to result in an “on” period of about 1.25 second that alternates with an “off” period of about 8.75 seconds. The step 140 of setting the valve duty cycle is shown in a box having dashed lines because this step can be eliminated or altered depending on, for example, the type and number of valves controlling the introduction of water into the steam generation chamber 74.
During the steam generator cleaning step 104, water is introduced into the steam generation chamber 74 to remove scale and/or sludge formed in the steam generation chamber 74. Introducing the water into the steam generation chamber 74 can also replace water already present in the steam generation chamber 74 with fresh water. The water already present in the steam generation chamber 74 has a relatively high content of soluble minerals due to the heating of the water in the steam generation step 102, and replacing the water already present in the steam generation chamber 74 with the fresh water, which has a relatively low content of soluble minerals, reduces the likelihood of scale and/or sludge formation. The introduction of water can optionally be preceded by a heating of the steam generation chamber 74, which heats the scale formed along the inside surface 72 of the steam generation chamber 74. The introduction of the water after the heating of the steam generation chamber 74 quickly cools the heated steam generation chamber 74 and thermally shocks the scale. The thermal shock can cause the scale to delaminate from the inside surface 72, and the water can rinse the loose scale out of the steam generator 60. The steam generator cleaning step 104 can proceed in any suitable manner to accomplish the cleaning of the steam generation chamber 74. Exemplary executions of the steam generator cleaning step 104, which can be employed with the steam generator 60 shown in
Referring now to
In step 154, the controller 84 determines whether the steam generator cleaning step 104A is complete. The determination of whether the steam generator cleaning step 104A is complete can be made in any suitable manner. For example, the steam generator cleaning step 104A can be considered complete after a predetermined period of time has elapsed, or, alternatively, after the temperature of the steam generation chamber 74, as sensed by the temperature sensor 82, has been reduced to a predetermined temperature, such as ambient temperature. The method 100 ends when it has been determined that the steam generation step 104A is complete.
Referring now to
The remaining portion of the steam generator cleaning step 104B can be considered a cooling portion and comprises step 164 of introducing water into the steam generation chamber 74 and step 166 of determining whether the steam generator cleaning step 104B is complete. The steps 164, 166 are essentially identical to the steps 152, 154 described above for the first exemplary execution of the steam generator cleaning step 104A. According to one embodiment of the invention, the water introduced in the step 164 is cold water so that a significant temperature differential exists between the temperature of the water and the temperature of the steam generation chamber 74. For example, the cold water can be the cold water source of a household water source, which typically has a cold water source and a warm or hot water source. As a result of the temperature differential, the cold water thermally shocks the heated scale formed on the inside surface 72 of the steam generation chamber 74. The scale cracks and delaminates from the inside surface 72 and is rinsed by the water flowing through the steam generation chamber 74.
As stated above, with the illustrated embodiment of the washing machine 10 in
The steam generator cleaning step 104 can also be considered a draining step because water remaining in the steam generation chamber 74 after the steam generation step 102 drains out of the steam generation chamber 74 in the steam generator cleaning step 104. When considered a draining step, the steam generator cleaning step 104 can include the step 152, 164 of introducing the water into the steam generation chamber 74, or the water remaining in the steam generation chamber 74 after the steam generation step 102 can simply be drained from the steam generation chamber 74 without the introduction of water. In this way, the steam conduit 66 of the illustrated embodiment of
The steam generator cleaning step 104 can optionally include introduction of one or more chemicals to facilitate cleaning of the steam generation chamber 74. For example, vinegar (i.e., acetic acid) or other acids can be employed to help clean, de-scale, and de-calcify the steam generation chamber 74. The chemical can be introduced at any suitable time, such as during the steps 152, 164 of introducing water during the steam generator cleaning step 104.
The method 100 can be executed with any type of steam generator, and the in-line steam generator 60 of
The second inlet valve assembly 64A comprises a first valve 90 and a second valve 92. The first valve 90 controls the flow of water through a first inlet branch 94 of the second supply conduit 62A, and the second valve 92 controls the flow of water through a second inlet branch 96 of the second supply conduit 62A. The first and second inlet braches 94, 96 join at a Y-connection upstream from the steam generation chamber 74A. The flow of water through the first valve 90 and the second valve 92 are respectively represented by dotted arrows B and dash-dot-dash arrows C in
The first valve 90 has a corresponding first flow rate, while the second valve 92 has a corresponding second flow rate different than the first flow rate. The flow rates can be selected based on a desired flow rate for different steps of the method 100. For example, the first valve 90 can be used for the steam generation step 102 when a relatively low flow rate is desired, while the second valve 92 can be used during the steam generator cleaning step 104 when a relatively high flow rate is desired, such as for the flushing of the steam generation chamber 74A. Using a relatively high flow rate during the steam generator cleaning step 104 can contribute to a more effective cleaning of the steam generation chamber 74A. As the flow rate increases, erosion of scale from the inside surface 72A of the steam generation chamber 74A can increase. As examples, the first flow rate can be about 0.25 liters per minute (LPM), and the second flow rate can be about 10 LPM. Similar to the second inlet valve 64 of the first embodiment steam generator 60, the first and second valves 90, 92 of the second inlet valve assembly 64A can be operated in any suitable manner, such as according to a duty cycle or in a continuous mode.
Referring now to
The steam generator 60B further comprises a heater 78B, which is shown as being embedded in the main body 70B. It is within the scope of the invention, however, to locate the heater 78B within the steam generation chamber 74B or in any other suitable location in the steam generator 60B. When the heater 78B is embedded in the main body 70B, the main body 70B is made of a material capable of conducting heat. For example, the main body 70B can be made of a metal, such as aluminum. As a result, heat generated by the heater 78B can conduct through the main body 70B to heat fluid in the steam generation chamber 74B. The heater 78B can be any suitable type of heater, such as a resistive heater, configured to generate heat. A thermal fuse 80B can be positioned in series with the heater 78B to prevent overheating of the heater 78B.
The steam generator 60B further includes a temperature sensor 82B that can sense a temperature of the steam generation chamber 74B or a temperature representative of the temperature of the steam generation chamber 74B. The temperature sensor 82B of the illustrated embodiment is a probe-type sensor that projects into the steam generation chamber 74; however, it is within the scope of the invention to employ temperature sensors in other locations. The temperature sensor 82B, the heater 78B, and the supply valve 180 can be coupled to a controller 84B, which can control the operation of heater 78B and the supply valve 180 in response to information received from the temperature sensor 82B.
The third embodiment steam generator 60B functions similarly to the first and second embodiment steam generators 60, 60A, except that the water and steam can leave the steam generation chamber 74B through different conduits rather than only flowing out of a single conduit. In particular, water, which can optionally be heated to form warm or hot water in the steam generation chamber 74B, intended for use in treating fabric can flow through the water outlet line 174, and steam intended for use in treating fabric can flow through the steam outlet line 176. Water not intended for use in treating fabric, such as water remaining in the steam generation chamber 74B after the steam generation step 102 or water flowing through the steam generation chamber 74B for the steam generator cleaning step 104, such as to flush the steam generation chamber 74B, can leave the steam generation chamber 74B through the drain conduit 178. In the illustrated embodiment of
While only the tank-type steam generator 60B has been shown as comprising the different outlets for the steam, for the water intended for use in treating the fabric, and for the water not intended for use in treating the fabric, it is within the scope of the invention for an in-line steam generator to comprise the different outlets. It is further contemplated that either type of steam generator can comprise a liquid inlet, an outlet coupled to at least one of the tub 14 and the drum 16 for both steam and water intended for use in treating the fabric, and a drain for draining water not intended for use in treating the fabric.
To prevent formation of scale and sludge, the water that enters the steam generation chamber 74B can be filtered, purified, or otherwise cleaned prior to entering the steam generation chamber 74B to remove or reduce the impurities necessary for the formation of scale and sludge. To illustrate this concept schematically, a portion of the washing machine 10 in
The water supply line 170 of
The filter 190 can be any suitable type of filter for removing impurities from water. For example, the filter 190 can comprise an ion exchange resin; a reverse osmosis filter; a catalytic alloy, such as nickel and palladium in various configurations, such as beads, pellets, and rods; a zeolite; and a nano- or ultra-filtration technique device. The filter 190 can also remove the impurities by using non-filter techniques, such as permanent magnets, electrostatic treatment devices, and mechanical precipitation devices, which filter the impurities mechanically by inducing flow patterns and vortices.
Depending on the type of filter technology employed, the washing machine 10 can include additional features for use with the filter 190. For example, a pump can be used to force the water through the filter 190 if the filter 190 is associated with a high pressure drop. The washing machine 10 can also include a reservoir to store filtered water upstream of the steam generator. When the reservoir is employed, the water can be filtered at any time and stored in the reservoir so that a stored volume of filtered water is available for use by the steam generator at all times. Alternatively, the water can be filtered in situ as the water is provided directly from the household water supply to the steam generator during operation of the steam generator.
The filter 190 can be replaceable and/or regenerable. When the filter 190 is replaceable, the entire filter 190 can be removed and replaced with a replacement filter. Alternatively, a filter media of the filter 190 can be replaced with a new filter media rather than replacing the entire filter 190. To facilitate replacement of the filter 190, the filter 190 can be coupled to the water supply line 170 in any suitable manner, such as by a quick-fit connection, including, but not limited to, a bayonet connection, a screw connection, and a snap-fit connection. When the filter 190 is regenerable, the filter 190 can be regenerated while coupled to the water supply line 170 or while removed from the water supply line 170.
The filter 190 can be employed with any type of steam generator and is not intended to be limited for use with the third embodiment steam generator 60B. Rather, the filer 190 can be utilized in combination with an in-line steam generator, such as the first and second embodiment steam generators 60, 60A, another tank-type steam generator, or any other kind of steam generator.
To reduce build-up of scale in the steam generator 60B, the inside surface 72B of the steam generation chamber 74B can have a surface treatment that reduces the tendency of the scale to bond with the inside surface 72B. The surface treatment can be applied to the entire inside surface 72B or only a portion of the inside surface 72B. The surface treatment can comprise any suitable surface treatment, such as a material added to the inside surface 72B in the form of a coating, a material embedded into the inside surface 72B, or a treatment that alters a texture of the inside surface 72B. As an example, the surface treatment can comprise polytetrafluoroethylene (PTFE), commonly known as Teflon®. The PTFE can be used as a surface treatment alone or in combination with other materials. For example, the PTFE can be impregnated into an anodized coating, such as an anodized aluminum coating. A commercial example of a PTFE-impregnated anodized coating is Nituff®, available from Nimet Industries. As another example, the PTFE can constitute part of coating having a nickel and phosphorous matrix, and a commercial example of such a coating is NiCoTef®, which is also available from Nimet Industries. The coating can be deposited with any suitable process, and the coating comprising the nickel and phosphorous coating and PTFE is especially suitable for deposition with electroless nickel plating.
The surface treatment can be employed with any type of steam generator and is not intended to be limited for use with the third embodiment steam generator 60B. Rather, the surface treatment can be utilized in combination with an in-line steam generator, such as the first and second embodiment steam generators 60, 60A, another tank-type steam generator, or any other kind of steam generator.
Other structures and methods related to scale and sludge control in steam washing machines are disclosed in the following patent applications, which are incorporated herein by reference in their entirety: our Docket Number US20050349, titled “Removal of Scale and Sludge in a Steam Generator of a Fabric Treatment Appliance;” and our Docket Number US20060227, titled “Draining Liquid From a Steam Generator of a Fabric Treatment Appliance,” both filed concurrently herewith.
While the invention has been specifically described in connection with certain specific embodiments thereof, it is to be understood that this is by way of illustration and not of limitation, and the scope of the appended claims should be construed as broadly as the prior art will permit.
