Patent Application
20080120790
1. Field of the Invention
The invention relates to a method for setting a liquid level in an automatic clothes washer.
2. Description of the Related Art
Automatic clothes washers are ubiquitous. Such appliances clean fabric items effectively, enabling the homeowner to complete other tasks or engage in more satisfying activities while doing the laundry. Modern clothes washers provide a multitude of options for matching a selected cleaning operation to the type of fabric comprising the laundry load and the degree of soiling of the laundry load. This includes setting a liquid level appropriate to the size and fabric type of the laundry load. Modern clothes washers also include sophisticated controllers that are programmed to maximize cleaning efficiency while minimizing water and power consumption. However, despite the capabilities of the modern clothes washer, the appliance remains limited in its ability to set the liquid level based on real-time information relating to the fabric items being laundered.
One type of conventional automatic clothes washer is provided with a drive motor, generally electrically powered, which is used to drive a cylindrical perforate basket during a spin cycle, and a clothes mover during wash and rinse cycles for agitating the laundry load within the basket.
In a conventional automatic clothes washer, cleaning of the fabric items is primarily attributable to three factors: chemical energy, thermal energy, and mechanical energy. These three factors can be varied within the limits of a particular automatic clothes washer to obtain the desired degree of cleaning.
The chemical energy is related to the types of wash aids, e.g. detergent and bleach, applied to the fabric items. All other things being equal, the more wash aid that is used, the greater will be the cleaning effect.
The thermal energy relates to the temperature of the fabric items. The temperature of the wash liquid typically is the source of the thermal energy. However, other heating sources can be used. For example, it is known to use steam to heat the fabric items. All things being equal, the greater the thermal energy, the greater will be the cleaning effect.
The mechanical energy is attributable to the contact between the clothes mover and the fabric items, the contact between the fabric items themselves, and the passing of the washing liquid through the fabric items. In washing machines with a clothes mover, in addition to the clothes mover contacting the fabric items, the clothes mover tends to cause the fabric items to contact themselves, and for the wash liquid to pass through the fabric items. All things being equal, the greater the amount of mechanical energy, the greater will be the cleaning effect.
These three factors can be adjusted to obtain the desired cleaning effect for the anticipated operating conditions and environment. For example, while the direct contact between the clothes mover and the fabric items is beneficial for laundering, it does cause greater physical wearing of the fabric items than the other two factors. Thus, for example, for more delicate clothing, it is desired to reduce the degree of contact. The liquid level in the basket affects all three factors (i.e. chemical energy, thermal energy, and mechanical energy) in the following way: A lower liquid level than required results in more contact between fabric items and the clothes mover and consequently more fabric damage. It also requires less thermal energy to reach to a preselected temperature. Furthermore, for a given amount of detergent, it leads to a more concentrated chemical wash. Conversely, more liquid results in less mechanical energy, more thermal energy, and a less concentrated wash. As a result, in both cases, the performance of the washer will be less than optimal based on the desired combination of the various energies.
Currently, the liquid level is adjusted based on amount of load (either by user or automatically) and even with contemporary washing machines, it has not yet been possible to determine the degree of contact between the fabric mover and the fabric items during the washing process. Thus, contemporary solutions are estimates or empirical data, both of which are typically determined based on a set of standard test conditions. Unfortunately, these standard test conditions are not guaranteed to be repeated when the clothes washer is used by the consumer, resulting in a compromised cleaning result.
An apparatus and method for determining the degree of engagement between a clothes mover and fabric items during a wash process, and a method for setting the liquid level in the automatic washer based on the degree of engagement between a clothes mover and the fabric items.
In the drawings:
The invention includes the real-time determining of the degree of engagement between a clothes mover and one or more fabric items during a clothes washing cycle. The invention further includes a method of setting a liquid level in a clothes washer based upon the mechanical energy imparted to the fabric items by the engagement of a clothes mover with fabric items in a laundry load, which equates to a normal force exerted on the clothes mover by the total weight of the fabric items. The method utilizes operational characteristics of a drive motor, such as angular velocity or current, to determine the degree of engagement of the clothes mover with the laundry load as a function of liquid level. The engagement of the clothes mover with the laundry load is compared with pre-determined threshold for the degree of engagement to control the introduction of liquid to set the desired liquid level.
Conventional automatic clothes washers enable a user to select one of several laundering options based upon the type of laundry load being placed in the clothes washer. For example, selectable options can include “normal,” “delicates,” “woolens,” and the like. These are typically referred to as “cycles.” As utilized herein, “laundering cycle” will refer to a specific cycle, such as “normal,” extending from the beginning of the cycle to its completion. A laundering cycle will generally consist of at least a wash cycle, a rinse cycle, and a spin cycle. The wash cycle, the rinse cycle, and the spin cycle may consist of several steps, such as a fill step, a drain step, a pause step, an agitation step, and the like. The invention can be used with any laundering cycle regardless of the types and combination of steps.
While the invention will be illustrated with respect to a low profile impeller, other clothes movers can be utilized without departing from the scope of the invention. For example, it is contemplated that the invention has applicability to horizontal axis washers as well as to the vertical axis washers. For purposes of this application, horizontal axis washer refers to those types of washers that move the fabric items primarily by lifting the fabric items and letting them fall by gravity, regardless of whether the axis of rotation is primarily horizontal, and vertical axis washer refers to those types of washers that move fabric items by a clothes mover, regardless of whether the axis of rotation is primarily vertical.
The clothes mover 20 can be operably connected to a drive motor 28 through an optional transmission 26 and drive belt 30. One or more well-known sensors 31 for monitoring motor speed, current, voltage, and the like, can be operably connected to the motor 28. Outputs from the sensors 31 can be delivered to a machine controller 32 in the control panel 14. In many applications, the sensors 31 form part of a motor controller coupled to the machine controller 32. The machine controller 32 can be adapted to send and receive signals for controlling the operation of the clothes washer 10, receiving data from the sensors 31, processing the data, displaying information of interest to a user, and the like.
The type and configuration of motor controller, sensors, 31, and machine controller 32 is not germane to the invention. Any suitable control system can be used that outputs the motor data, such as speed and current, as described in greater detail below.
The clothes washer 10 can also be connected to a source of water 34 which can be delivered to the tub 16 through a nozzle 36 controlled by a valve 38 operably connected to the machine controller 32. The valve 38 and the machine controller 32 can enable a precise volume of water to be delivered to the tub 16 for washing and rinsing.
The drive motor 28 can drive the clothes mover 20 in an oscillating manner, first in a forward direction, referred to herein as a forward stroke, then in a backward direction, referred to herein as a backward stroke. The clothes mover 20 can move in a forward direction through a preselected angular displacement, for example, ranging from 180° to 720°. The clothes mover 20 can move in a backward direction through a similar preselected angular displacement. A complete forward stroke and backward stroke is referred to herein as an oscillation cycle.
In a typical wash cycle, multiple fabric items, which collectively form a laundry load, are placed in the basket on top of the clothes mover 20. Some of the fabric items will be in direct contact with the clothes mover 20 and some will not. As the clothes mover 20 moves, the individual fabric items will be moved directly or indirectly by the clothes mover 20 to impart mechanical energy to the items, which will move the fabric items about the interior of the wash chamber.
As illustrated in
Referring now to
The intermittent contacting and slipping of the vane 40 with respect to the clothes mover 20 results in an intermittent engagement of the fabric item with the clothes mover 20 by the application of the weight of the fabric item 50 to the clothes mover 20, which amounts to a loading and unloading of the clothes mover 20. The engagement and disengagement associated with the loading and unloading present as a change in speed of the clothes mover 20, which is sensed by the sensors 31. In response, the controller 32, which typically tries to move the motor 28 at a predetermined set speed for the given cycle, will increase or decrease the current to the motor 28 to attempt to maintain the set speed.
The magnitude and frequency of engagement is impacted by several factors, only some of which will now be described. If the load comprises multiple fabric items, their total weight will impact the clothes mover. Thus, all else being equal, the greater the size of the laundry load, the greater will be the loading of the clothes mover by the fabric items. The increased volume of the greater laundry load will also tend to inhibit the free movement of the fabric items within the wash chamber, which will tend to keep the fabric items in contact with the clothes mover 20 as there is less space for the fabric items to move and their individual free movement is inhibited by surrounding fabric items.
Wet fabric items tend to create greater frictional resistance with the clothes mover than dry fabric items. However, as liquid level increases in the wash chamber to the point where the fabric items are fully submerged, the additional liquid brings into effect the buoyancy of the fabric items, which has an opposite effect than the weight force of the fabric items. In some instances, the liquid may be sufficiently deep and the clothes mover may sufficiently agitate the liquid that some or all of the fabric items are suspended in the liquid above the clothes mover 20, which will greatly reduce the loading of the clothes mover 20 by the fabric items. Thus, all things being equal, the deeper the liquid, the more the degree of loading and unloading will be minimized.
Looking at particular scenarios, if the clothes washer 10 contains only liquid, i.e. no fabric items, the loading/unloading of the clothes mover 20 is minimal to nonexistent during the oscillation cycle because the clothes mover 20 is, for the most part, in contact with the same amount of liquid throughout each stroke, which essentially places a generally constant load on the clothes mover 20.
As illustrated in
The backward direction region 76 is similarly divided into an acceleration step 76A, a plateau 76B, and a deceleration step 76C. Thus, when the clothes mover 20 transitions from the forward stroke to the backward stroke, the motor current 72 decreases to a zero value 94, and the motor speed 70 responsively decreases to a zero or nearly zero value 96. While the decrease in speed is not shown going to zero in
During the forward and backward strokes as illustrated in
Looking more closely at the ripples of the motor speed waveform, the ripples can be separated into peaks comprising positive peaks 82a-d, 86a-d and negative peaks 84a-d, 88a-d. The amplitude or magnitude of the ripples can be determined by comparing the peaks to the motor speed set point. For example, the difference between the positive speed amplitude 82a-d and the target rotation speed can be a first amplitude value. Similarly, the difference between the negative speed amplitude 84a-d and the target rotation speed, preferably expressed as an absolute value, can be a second amplitude value. Alternatively, the area of the ripple (or total current) can be used as an indication of load. The motor speed 70 has a quasi-sinusoidal waveform for which a frequency can be determined using the peaks for the time of the plateau 74B, 76B.
The motor-current waveform 72 is similar to that of the motor speed in that the ripples can be separated into peaks comprising positive peaks 90a-d, 94a-d and negative peaks 92a-d, 96a-d. The number of peaks in the current waveform can also be used to calculate the frequency of the waveform.
As is shown in
These amplitude values for either or both of the motor speed and motor current can be stored by the machine controller 32 as individual data values as well as a cumulative value. Preferably, the amplitude values can be averaged and, more preferably, a running average of the amplitude values can be determined and stored by the machine controller 32.
While the waveforms containing data for the motor speed and the motor current have been available to those skilled in the art for a long time, the Inventors have determined that the motor speed data and motor current data can be used to determine the degree of engagement between the fabric items and the clothes mover. Additionally, this degree of engagement between the fabric items and the clothes mover is determined from the motor speed data and motor current data in real-time. In this sense, the use of the data amounts to a real-time sensor placed in the wash chamber for determining the degree of engagement. The degree of engagement increases with decreased liquid level. Thus, the use of the motor speed/current data can be thought of as a “virtual” liquid-level sensor. Such a sensor has never before been available.
The ability to determine or sense the degree of engagement is very beneficial to improving the laundering performance. The interaction of the vanes 40 with the laundry load results in mechanical action or work being delivered to the laundry load, which can both contribute a laundering effect to the load and cause abrasion, fracture, and wear of the fabric items. Some mechanical action is needed to obtain the desired amount of laundering. Mechanical action beyond that needed to launder the fabric items is not needed and not desired as it wears the fabric items without additional laundering benefit. Also, for some fabric items, especially delicate fabric items, it is desirable to keep the mechanical action below a predetermined magnitude. Therefore, it is important to control the degree of engagement between the fabric items and the clothes mover.
Once one has the ability to determine the liquid level, it is then possible to manipulate the wash cycle accordingly to select an optimal liquid level for a wash cycle, thereby reducing the volume of liquid consumed. The clothes washer also consequently requires less energy in filling and draining the wash tub. An adaptive liquid level indicator also facilitates control of the degree of engagement by controlling the liquid level in the clothes washer. All things being equal, the greater the liquid in the wash chamber, the less will be the degree of engagement or mechanical action between the clothes mover and the fabric items. Thus, the determined degree of engagement can be used to adjust the liquid level and thereby control the degree of engagement.
The relationship between the motor speed and motor current and the degree of engagement will be considered in greater detail. The amplitude of the motor speed or current peaks can provide an accurate estimate of the degree of engagement of the clothes mover 20 with the laundry load, thereby enabling the liquid level to be set, since as discussed above, the degree of engagement will decrease as the liquid level increases. The degree of engagement of a clothes mover with fabric items in a laundry load can be given by the following relationship:
Engagement=cl*Peak Amplitude
where
Engagement is a function of the magnitude of contact between the clothes mover 20 and the fabric items. The amplitudes of the ripples correlate with the degree of engagement of the fabric items with the clothes mover 20. This degree of engagement is defined by the cumulative loading/unloading of the clothes mover 20 by the fabric load and liquid.
Peak Amplitude can be determined from the waveform data. It can be calculated on a peak-by-peak basis or as a running average. The running average can be a cumulative running average, a moving window running average, or a weighted running average, for example. The running average can be calculated in a variety of ways, including, for example, multiple peak basis, stroke-by-stroke basis, or across multiple strokes. Thus, the timing of the calculation can be selected as desired. The amplitude can be calculated relative to any reference value, including the motor set speed. Other illustrative reference values are zero level, average plateau speed for example. It is currently contemplated that the Peak Amplitude will be calculated as a running average of the amplitudes of the peaks relative to a target clothes mover motor speed set point across multiple strokes.
Referring to
The machine controller 32 uses the determination of the degree of engagement to control the operation of the clothes washer. For example, during a fill step in a wash cycle, for example, the clothes mover 20 is rotated through a preselected number of preliminary oscillation cycles, for example five, while the clothes washer 10 is filled with liquid, or after an initial filling of the clothes washer 10. Thus, the clothes mover 20 will be rotated through five forward strokes and five backward strokes while the machine controller 32 keeps an average running total of the degree of contact. This can be accomplished by the machine controller receiving data samples of the motor speed from the sensor 31, trapping the peak values, determining an amplitude relative to the motor set speed, and maintaining an average running total of the amplitudes. While the number of preliminary oscillation cycles can be other than five, it has been shown that five cycles is sufficient to eliminate any variations inherent in the system.
At the end of the five cycles, the running average is compared to a preselected threshold value, which is empirically determined for different clothes washers, and is established based upon factors such as fabric type, laundry load size, laundering cycle, clothes mover configuration, motor type, transmission type, and the like. Thus, a matrix of threshold amplitude values will be developed for a particular clothes washer configuration, and these values will be stored in the machine controller 32. If the running average is greater than the threshold, then no more liquid need be added to the wash chamber. If liquid is currently being added to the wash chamber, then the addition of liquid is stopped. If the running average is less than the threshold, then more liquid needs to be added to the wash chamber. If liquid is currently being added to the wash chamber, it is continued. If liquid is not currently being added, then it is started.
This liquid level adjustment can be conducted at any time during the wash cycle. For example, it can be part of the filling step or it can be part of the wash or rinse steps. In this way, the fabric items are protected from unnecessary mechanical action from the clothes mover 20. Having the optimal level of liquid also facilitates an optimal chemical wash performance. This is so because having greater than the optimal volume of liquid reduces the chemical detergent concentration in the tub, whereas having less than the optimal volume of liquid reduces the circulation of the detergent through the clothes.
The predetermined threshold value of amplitude can represent an optimal liquid level reflecting an optimal combination of cleaning effort and fabric protection. An optimal liquid level has been reached when the amplitude running average reaches the preselected threshold value of amplitude.
The invention described herein provides an optimized laundering cycle by setting a liquid level sufficient for satisfactorily cleaning a laundry load, thereby reducing energy and water usage. At the same time, optimizing the liquid level minimizes the progressive wear to the laundry load caused by a less than optimal liquid level. Thus, the items being laundered have an enhanced lifespan, thereby saving the consumer costs related to replacement of such items. Finally, the utilization of motor speed or motor current in determining an optimal liquid level requires no additional instrumentation, thereby minimizing additional cost. The invention simply utilizes readily available information in a new manner to control an operation in order to optimize the laundering performance of a clothes washer.
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. Reasonable variation and modification are possible within the scope of the forgoing disclosure and drawings without departing from the spirit of the invention, which is defined in the appended claims.
