Patent Application
20090241270
The invention relates to a method for determining load size and/or setting a water level in a washing machine. For a wash process of a washing machine, the water level in the tub is typically set based on the size of a fabric load and, sometimes, the fabric type of the fabric load. The size of the fabric load may be manually input by the user through a user interface or may be automatically determined by the washing machine. For manual input by the user, the user may oftentimes overestimate or underestimate the load size, thereby resulting in too much or too little water, respectively, for the wash process. Too much water is wasteful, and too little water may lead to an insufficient wash performance. Many methods are known for the washing machine to automatically determine the load size and/or fabric type, such as by employing an output of the motor that drives the drum within the tub and the agitator within the drum. However, some lower end washing machines have motors that do not provide output useful for determining load size or have other limitations that preclude or make undesirable known methods for automatically determining load size.
A method for determining a size of a fabric load according to one embodiment of the invention in a washing machine comprising a wash tub, an agitator for agitating a fabric load in the tub, and a pressure sensor for sensing a level of water in the tub comprises determining whether the fabric load is a first qualitative size based on a time of supplying water to reach a timing water level in the tub, and if the fabric load is not the first qualitative size, determining whether the fabric load is a second qualitative size greater than the first qualitative size based on a variation in an output from the pressure sensor during agitation of the water and fabric load with the water at a agitation water level in the tub greater than the timing water level.
In the drawings:
Referring now to the figures,
The washing machine 10 includes a cabinet or housing 12, an imperforate tub 14, a perforated basket or drum 16 mounted within and rotatable relative to the tub 14, an agitator 18 mounted within and rotatable relative to and/or with the basket 16, and an electrically driven motor 20 operably connected via a transmission 22 to the agitator 18 and/or the basket 16. The transmission 22 may be a gear driven direct drive. The motor may be a brushless permanent magnet (BPM) motor direct drive, which may be coupled to and drive the transmission. An openable lid 24 on the top of the cabinet 12 provides access into the basket 16 through the baskets' open top. A user interface 28, which may be located on a console 30, may include one or more knobs, switches, displays, and the like for communicating with the user, such as to receive input and provide output.
A spraying system 40 may be provided to spray liquid (water or a combination of water and one or more wash aids) into the open top of the basket 16 and on top of any fabric load placed within the basket 16. The spraying system 40 may be configured to supply water directly from a household water supply and/or from the tub and spray it onto the fabric load. The spraying system 40 may also be configured to recirculate liquid from the tub, include a sump in the tub, and spray it onto the top of the fabric load. Other embodiments of the invention may use other water delivery techniques known to those skilled in the art.
As illustrated, the spraying system 40 may have one or more spray heads 42 directed into the open top of the basket 16. A liquid supply line (not shown) supplies liquid to a distribution manifold 46 integrated with the balancing ring to effect the supply of liquid to the spray heads 42. The supply line may be fluidly coupled to either or both of the household water supply or the tub as previously described. When liquid is supplied to the supply line from either the household supply or the tub, the liquid is directed to the spray heads 42 through the manifold 46 and is then emitted through the spray heads 42 into the open top of the basket 16 and onto any fabric load in the basket 16.
If the number, location, and coverage of the spray heads 42 is insufficient to substantially cover the basket 16, the basket may be rotated so that the fabric load is rotated beneath the spray heads for a more even wetting. However, the spray heads 42 as illustrated may be located and their spray coverage controlled such that they sufficiently evenly wet the fabric load in the basket without the need for rotating the basket, which likely reduces the cost and complexity of the motor, transmission, and controller.
Referring now to
A controller 38 communicates with several working components and/or sensors in the washing machine 10, such as the motor 20, the user interface 28, the water supply control 32, the pressure sensor 34, and the timer 36, to receive data from one or more of the working components or sensors and may provide commands, which may be based on the received data, to one or more of the working components to execute a desired operation of the washing machine 10. The commands may be data and/or an electrical signal without data. Many known types of controllers may be used for the controller 38. The specific type of controller is not germane to the invention.
The washing machine 10 shown in the figures and described herein is a vertical axis washing machine. As used herein, the “vertical axis” washing machine refers to a washing machine having a rotatable drum that rotates about a generally vertical axis relative to a surface that supports the washing machine. However, the rotational axis need not be vertical; the drum may rotate about an axis inclined relative to the vertical axis. Typically, the drum is perforate or imperforate and holds fabric items and a fabric moving element, such as an agitator, impeller, pulsator, infuser, nutator, ribbing or baffles on the interior wall of the basket or drum 16, and the like, that induces movement of the fabric items to impart mechanical energy directly to the fabric articles or indirectly through wash water in the drum for cleaning action. The clothes mover is typically moved in a reciprocating rotational movement, although non-reciprocating movement is also possible.
Although the washing machine 10 is a vertical axis washing machine, the methods described below may be employed in any suitable washing machine having a fabric moving element, including washing machines other than vertical axis washing machines. As used herein, “agitator” refers to any type of fabric moving element and is not limited to the structure commonly associated with an agitator, such as the structure shown in
Typically, a washing machine performs one or more manual or automatic operation cycles, and a common operation cycle includes a wash process, a rinse process, and a spin extraction process. Other processes for operation cycles include, but are not limited to, intermediate extraction processes, such as between the wash and rinse processes, and a pre-wash process preceding the wash process, and some operation cycles include only a select one or more of these exemplary processes. Regardless of the processes employed in the operation cycle, the methods described below relate to determining a size of the fabric load and/or setting an operational water level for a process in the operation cycle.
The flow chart in
The term operational water level is used to reference the level of water in the tub corresponding to a volume of water for implementing one or more steps of a wash cycle. The term operational water level is to be distinguished from the term water level, which is used to reference any water level in the tub and expressly includes operational water levels.
Referring generally to
There may not an exact correlation between the time for water to start collecting in the tub and the load size because of environmental factors. For example, if the load is small enough, it may not cover the bottom of the basket 16 and the water would pass directly from the spraying system 40 and into the tub. This may be referred to as the water bypassing the clothing, which tends to result in the time value indicating a smaller load than is present. The fabric load may also be placed in the basket 16 in such a way that water will pool on the fabric and not be absorbed, which tends to result in the time value indicating a larger load than is present. The mix of fabrics in the fabric load may also affect the time to fill the tub 14. For example, a fabric load of synthetic fabrics typically absorbs less water than the same size fabric load of cotton fabrics; thus, the time to fill the tub 14 with water to a predetermined water level may be less for the synthetic fabric load than for the cotton fabric load. These potential errors in the accuracy of the time to fill and the actual load size may be addressed by the selection of operational water levels that span any anticipated error.
While the time to fill may be determined by filling to any water level, to minimize the cycle time, the time to fill determination may be measured until the pressure sensor first begins to sense water in the tub. When the pressure sensor first senses water in the tub is sometimes referred to as the first meaningful output from the pressure sensor 34. The first meaningful output of the pressure sensor typically corresponds to a water level in the tub. That is, it is the first sensed water level that the pressure sensor can sense. This first sensed water level depends, at least in part, on the configuration of the washing machine 10, such as the location of the pressure sensor 34. Alternatively, the first sensed water level may correspond to a predetermined output from the pressure sensor 34, which is indicative of a water level above the first sensed water level. However, terminating the time to fill at a water level above the first sensed water level will increase the overall cycle time. The first sensed water level may be less than, equal to, or greater than a level of water for a wash process of an operation cycle of the washing machine 10. As one example, the first sensed water level may be about 1 inch of water in the tub 14. For purposes of this description, the time to fill (t) will be described in the context of the time to fill to the first sensed water level, with it being understood that any water level may be used as the level for terminating the time to fill. Therefore, the term timing water level will be used to generically refer to the water level at which the time to fill is determined, with it being understood that this term may apply to any water level and not limited by the manner in which the water level is sensed.
The relationship between load size and time to fill is illustrated in
Each plot line has the same general shape where the pressure remains constant (horizontal portion) and then, at an inflection point, trends upwardly (angled portion). The horizontal portion represents the time when water is being added to the basket 16 but the sensor does not yet sense any water in the tub. That is, the water in the tub has not yet reached the timing water level. Most of the water during this time is being absorbed by the fabric load. The inflection point represents the time when the sensor first senses water in the tub and is the timing water level. That is, the time it takes to reach the inflection point is the time to fill. After the inflection point is reached, most of the additional water is not absorbed by the fabric load and goes into the tub, resulting in an increase in the water level, which results in an increased pressure sensed by the pressure sensor.
In comparing the various plots, it can be seen that for a given fabric load type, the time to reach the inflection point, i.e., the time to fill, increases with load size. This is true for either the blend load type or the all cotton load type. Therefore, the time to fill may be used to determine relative load sizes.
It can also be seen that in some instances this correlation does not hold true if there is when there is a large difference in the absorbency of the fabric types. For example, the 3 lb cotton load reaches its inflection point about the same time as the 8 lb blend load, and the 8 lb cotton load reaches its inflection point after the 13 lb blend load. To address the variation attributable to the absorbency variation of the load types, the time to fill and corresponding operation water level may be selected to obtain the best/desired wash performance. For example, in a vertical axis machine, operational water levels are usually set based on the weight of the fabric load and it is generally considered better to have too much water for a given load weight than too little water because it minimizes the wear on the clothing from the agitator and has better wash performance. Therefore, the inflection points for the blend loads may be used as indicators for the cotton loads to ensure that enough water is added when setting the operational water level.
The plots in
With this background, an exemplary implementation of the method in
At the agitation water level, the agitator 18 (or other clothes mover) rotates or otherwise agitates the fabric load and the water in the tub 14 during a step 132. Additionally, the output from the pressure sensor 34 may be monitored and employed for determining whether the fabric load is a second size greater than the first size. The agitation may occur for any suitable time, and an exemplary agitation time is about 6 seconds. The agitator 18 may rotate at any suitable speed, and, if the agitation comprises reciprocal rotation of the agitator 18, the agitator 18 may rotate in each direction for any suitable time.
Variation in the output signal from the pressure sensor 34 during agitation of the fabric load and the water in the tub 14 may be indicative of the load size. The exact cause of the variation in the output signal is not completely known. It is currently thought that as the agitator 34 rotates, the fabric load moves, the water in the tub 14 moves and may splash, and the tub 14 itself may move or wiggle. One or more of these effects may result in a ripple or variation in the output from the pressure sensor 34, and the magnitude of the ripple or variation increases with increasing load size.
Because the magnitude of the variation in the output from the pressure sensor 34 may be indicative of the load size, the method 100 employs the variation to infer whether the fabric load is a second size greater than the first size. The method 100 determines if the variation meets a second predetermined condition; if the variation meets the second predetermined condition, then the method 100 infers that the fabric load is the second size. In particular, for this example, the variation determined at the step 132 is compared to an empirically (or otherwise) determined predetermined variation at a step 134. If the variation is less than the predetermined variation, then at step 136, the method 100 infers the load size to be the second size, which may be a medium size, and sets the operational water level to a second operational water level, which, for this example, may be thought of as a medium load size operational water level. If the second operational water level is greater than the agitation water level, then the water may be supplied to the second operational water level in a step 138. In one embodiment, the second operational water level is equal to the agitation water level, in which case, no further water supply occurs at the step 138.
If the variation is determined not to be less than the predetermined variation at the step 134, then the load size is inferred to be a third size, greater than the first and second sizes. In one embodiment, the third size may be a large load size. Additionally, the water level may be set to a third operational water level, greater than the first and second operational water levels. The third operation water level may be thought of as the large load size operational level for this example. In one embodiment, the third operational water level may correspond to about 14 inches of water in the tub 14. If the load size is inferred to be the third load size in the step 140, then the water may be supplied to the third operational water level in a step 142.The graph in
When the pressure level reaches a level indicative of the agitation water level, which is slightly greater than 260 mm Hg in the exemplary graph, the agitation occurs and induces the variation in the magnitude of the pressure level. The variation in the output from the pressure sensor 34 is clearly smaller for the 8 pound loads, about 8 mm Hg, than for the 13 pound loads, about 15 mm Hg or greater, regardless of the load type. If the predetermined variation is selected to be between about 8 and less than about 15 mm Hg, then all of the 8 pound fabric loads would be inferred to be the second size, and all of the 13 pound loads would be inferred to be the third size.
After the load size is inferred and/or the operational water level is set during one of the steps 126, 136, and 140 and, optionally, water supplied to the corresponding operational water level during one of the steps 128, 138, and 142, the process associated with the method 100 continues in any desired manner.
In the method 100, the operational water level may be set without a corresponding inference of load size and vice-versa. It is contemplated that the method 100 may be employed only for setting the operational water level, in which case the inference of the load size may not be necessary. It is also contemplated that the method 100 may be employed for only determining the load size, and the inferred load size may thereafter be employed to determine other parameters for the operation cycle. It is also contemplated for the method 100 to both infer the load size and set the operational water level.
When the method 100 is employed for determining load size, the inferred load size may be a qualitative load size wherein the fabric load is assigned to a category, such as small, medium, and large, of load size based on the qualities of the fabric load. That is, the size of the load is not weighed or otherwise to directly measured to obtain a quantitative or numerical measurement. While the qualitative load size does not correlate with a direct numerical measurement of the weight or volume of the fabric load, an estimated or empirical weight or weight range may be associated to the qualitative load size (e.g., a medium load size may be described as an 8-12 pound load size). Further, a qualitative load size, which, as described above, may be indicative of both the weight of the fabric load and the type of fabric load.
The method 100 may be adapted for determining more or less than three load sizes, and, similarly, setting more or less than three operational water levels. In one example, the variation in the output from the pressure sensor 34 may be compared to more than one predetermined variation, which may enable more load sizes and operational water levels. For example, using two predetermined variations, wherein each predetermined variation defines between two load sizes and/or operational water levels, allows the use of a fourth load size, which may be an extra large load size, and/or a fourth operational water level.
The time and the variation of the output from the pressure sensor 34 may be employed directly as a time and a pressure level for the decisions made in the steps 124, 134 or may be modified in any suitable manner. In other words, the time and/or the pressure sensor output may be altered, such as by being multiplied by another variable, to refine the variables.
The method 100 may be adapted for use with different washing machines and differing water flow rates. Various aspects, such as the predetermined time and variation and number of load sizes and operational water levels, may depend on the configuration of the washing machine 10 and the external water supply. The particular shape of a curve of pressure level as a function of time may change for differing configurations of washing machines, and the curves may shift along the time axis for differing water flow rates (e.g., shift to longer times for lower water flow rates), but the relative behavior of pressure level as a function of time for a group of given fabric load weights and fabric types using a given washing machine configuration with a given water flow rate should remain the same or at least similar enough so that the method 100 may be applied regardless of the washing machine configuration and water flow rate.
The method 100 may be used for an automatic water level control system in lower end washing machine having simple electromechanical components, such as the timer. The method 100 may also be combined with a flow meter, flow restrictor, alternate fill method, and/or inputs by the user, such as fabric type.
The above description and the figures refer to the supply of water to the tub 14. The water may be water alone or water in combination with an additive, such as a wash aid, including, but not limited to a detergent, a bleach, an oxidizer, a fabric softener, etc. Any additive supplied to the tub 14, either through a detergent dispenser or manually added directly into the basket 16 or the tub 14, may affect the output of the pressure sensor 34, and the empirically determined predetermined time and variation(s) may be set to account for such effects.
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.
