Patent Application
20130047344
Laundry treating appliances, such as a washing machine in which a drum defines a treating chamber for receiving a laundry load, may implement a cycle of operation for treating laundry. The cycle of operation may include different phases during which liquid is applied to the laundry load. The cycle of operation my further include phases during which the applied liquid may be removed from the laundry load, an example of which is an extraction phase where a drum holding the laundry rotates at speeds high enough to impart a sufficient centrifugal force on the laundry load to remove the liquid.
During the extraction phase, if the laundry load is not uniformly distributed in the rotating drum, an imbalance may result. If a sufficiently large imbalance is present, the laundry treating appliance may experience undesirable vibrations and movements when the drum rotates at high spin speeds.
The invention relates to a method of operating a laundry treating appliance having a rotating drum, a motor, and a controller by rotating the drum according to a speed profile, determining a magnitude of an imbalance in the drum during the rotating of the drum, determining a location of an imbalance in the drum during the rotating of the drum, and altering the rotation of the drum from the speed profile to form a counter balance to the imbalance with a subset of the multiple articles forming the laundry load.
In the drawings:
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 having a rotatable drum, perforate or imperforate, that holds fabric items and a clothes mover, such as an agitator, impeller, nutator, and the like within the drum. The clothes mover moves within the drum to impart mechanical energy directly to the clothes or indirectly through liquid in the drum. The liquid may include one of wash liquid and rinse liquid. The wash liquid may have at least one of water and a wash aid. Similarly, the rinse liquid may have at least one of water and a rinse aid. The clothes mover may typically be moved in a reciprocating rotational movement. 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 may 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 rubbing against one another as the drum rotates. 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 may rotate about an axis inclined relative to the horizontal axis. 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. Mechanical energy is imparted to the clothes by the tumbling action formed by the repeated lifting and dropping of the clothes. Vertical axis and horizontal axis machines are best differentiated by the manner in which they impart mechanical energy to the fabric items. The illustrated exemplary washing machine of
The washing machine 10 may include a cabinet 12, which may be a frame to which decorative panels are mounted. A controller 14 may be provided on the cabinet 12 and controls the operation of the washing machine 10 to implement a cycle of operation. A user interface 16 may be included with the controller 14 to provide communication between the user and the controller. The user interface 16 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 rotatable drum 18 may be disposed within the interior of the cabinet 12 and defines a treating chamber 20 for treating laundry. The rotatable drum 18 may be mounted within an imperforate tub 22, which is suspended within the cabinet 12 by a resilient suspension system 24. The drum 18 may include a plurality of perforations 26, such that liquid may flow between the tub 22 and the drum 18 through the perforations 26. The drum 18 may further include a plurality of lifters 28 disposed on an inner surface of the drum 18 to lift a laundry load (not shown here) received in the laundry treating chamber 20 while the drum 18 rotates.
While the illustrated washing machine 10 includes both the tub 22 and the drum 18, with the drum 18 defining the laundry treating chamber 20, it is within the scope of the invention for either the drum 18 or tub 22 to define the treating chamber 20 as well as the washing machine 10 including only one receptacle, with the one receptacle defining the laundry treating chamber for receiving a laundry load to be treated.
A motor 30 is provided to rotate the drum 18. The motor 30 includes a stator 32 and a rotor 34, which are mounted to a drive shaft 36 extending from the drum 18 for selective rotation of the treating chamber 20 during a cycle of operation. It is also within the scope of the invention for the motor 30 to be coupled with the drive shaft 36 through a drive belt and/or a gearbox for selective rotation of the treating chamber 20.
The motor 30 may be any suitable type of motor for rotating the drum 18. In one example, the motor 30 may be a brushless permanent magnet (BPM) motor having a stator 32 and a rotor 34. Other motors, such as an induction motor or a permanent split capacitor (PSC) motor, may also be used. The motor 30 may rotate the drum 18 at various speeds in either rotational direction.
The washing machine 10 may also include at least one balance ring 38 containing a balancing material moveable within the balance ring 38 to counterbalance an imbalance that may be caused by laundry in the treating chamber 20 during rotation of the drum 18. The balancing material may be in the form of metal balls, fluid or a combination thereof. The balance ring 38 may extend circumferentially around a periphery of the drum 18 and may be located at any desired location along an axis of rotation of the drum 18. When multiple balance rings 38 are present, they may be equally spaced along the axis of rotation of the drum 18.
The washing machine 10 of
A liquid conduit 50 may fluidly couple the treatment dispenser 46 with the tub 22. The liquid conduit 50 may couple with the tub 22 at any suitable location on the tub 22 and is shown as being coupled to a front wall of the tub 22 in
The liquid supply and recirculation system may further include one or more devices for heating the liquid such as a steam generator 65 and/or a sump heater 63. The steam generator 65 may be provided to supply steam to the treating chamber 20, either directly into the drum 18 or indirectly through the tub 22 as illustrated. The inlet valve 48 may also be used to control the supply of water to the steam generator 65. The steam generator 65 is illustrated as a flow-through steam generator, but may be other types, including a tank type steam generator. Alternatively, the heating element, in the form of the sump heater 63, may be used to heat laundry (not shown), air, the rotatable drum 18, or liquid in the tub 22 to generate steam, in place of or in addition to the steam generator 65. The steam generator 65 may be used to heat to the laundry as part of a cycle of operation, much in the same manner as heating element 63, as well as to introduce steam to treat the laundry.
Additionally, the liquid supply and recirculation system may differ from the configuration shown in
The controller 14 may be provided in the cabinet 12 and communicably couple one or more components to receive an output signal from components and control the operation of the washing machine 10 to implement one or more cycles of operation, which is further described in detail with reference to
The memory 64 may also be used to store information, such as a database or table, or to store data received from one or more components of the washing machine 10 that may be communicably coupled with the controller 14 as needed to execute the cycle of operation.
The controller 14 may be operably coupled with one or more components of the washing machine 10 for communicating with and controlling the operation of the component to complete a cycle of operation. For example, the controller 14 may be coupled with the user interface 16 for receiving user selected inputs and communicating information with the user. The user interface 16 may be provided that has operational controls such as dials, lights, knobs, levers, buttons, switches, sound device, and displays enabling the user to input commands to a controller 14 and receive information about a specific cleaning cycle from sensors (not shown) in the washing machine 10 or via input by the user through the user interface 16.
The user may enter many different types of information, including, without limitation, cycle selection and cycle parameters, such as cycle options. Any suitable cycle may be used. Non-limiting examples include, Heavy Duty, Normal, Delicates, Rinse and Spin, Sanitize, and Bio-Film Clean Out.
The controller 14 may further be operably coupled to the motor 30 for controlling at least one of the direction, rotational speed, acceleration and power consumption of the motor 30, and the treatment dispenser 46 for dispensing a treating chemistry during a cycle of operation. The controller may be coupled to the steam generator 65 and the sump heater 63 to heat the liquid as required by the controller 14. The controller may also be coupled to the pump 56 and inlet valve 48 for controlling the flow of liquid during a cycle of operation.
The controller 14 may also receive input from one or more sensors 70, which are known in the art. Non-limiting examples of sensors that may be communicably coupled with the controller 14 include: a treating chamber temperature sensor, a moisture sensor, a weight sensor, a drum position sensor, a motor speed sensor, a motor torque sensor 68 or the like.
The motor torque sensor 68 may include a motor controller or similar data output on the motor 30 that provides data communication with the motor 30 and outputs motor characteristic information such as oscillations, generally in the form of an analog or digital signal, to the controller 14 that is indicative of the applied torque. The controller 14 may use the motor characteristic information to determine the torque applied by the motor 30 using a computer program that may be stored in the controller memory 64. Specifically, the motor torque sensor 68 may be any suitable sensor, such as a voltage or current sensor, for outputting a current or voltage signal indicative of the current or voltage supplied to the motor 30 to determine the torque applied by the motor 30. Additionally, the motor torque sensor 68 may be a physical sensor or may be integrated with the motor 30 and combined with the capability of the controller 14, may function as a sensor. For example, motor characteristics, such as speed, current, voltage, torque etc., may be processed such that the data provides information in the same manner as a separate physical sensor. In contemporary motors, the motors often have their own controller that outputs data for such information.
Prior to describing a method of operation, a brief summary of the underlying phenomena may be useful to aid in the overall understanding. When the drum rotates with a rotational axis of the drum, the drum may show an excursion with a rotational movement off the rotational axis. The excursion may lead to a contact between the drum and the tub during a cycle of operation. Excursion of the drum may be observed while the motor rotates the drum at various speeds in either rotational direction in accordance with a cycle of operation. While there may be multiple reasons or factors for such excursion, one of the common reasons is the presence of non-uniformly distributed laundry load in the interior of drum, which may result in an imbalance for a given rotating speed of the drum.
Drum excursions that are more apt to result in contact with other components of the laundry treating appliance tend to happen at higher drum rotational speeds, especially rotational speeds where at least a portion of the laundry is ‘satellized’ or ‘plastered’ within the drum, which may be referred to as a spin speed. By satellized or plastered, it is meant that the centrifugal force applied to at least some of the laundry by the rotating drum is sufficient to hold the at least some of the laundry at a fixed position on the drum. The magnitude of such a force is typically equal to or greater than the force of gravity, 1G, but may vary, for example because the rotational axis may be at an angle to the horizontal. The greatest rotational speeds of the drum typically occur during an extraction phase, where liquid is removed from the laundry by centrifugal force. Contemporary laundry treating appliances have rotational speeds up to 1400 rpm for extraction phases when satellizing occurs at around 90 rpm, which is dependent on drum size.
For a variety of reasons, not all items in a laundry load will be satellized at the same time. For example, not all the laundry articles 84 that make up the laundry load 80 are located an equal distance from the axis of rotation. The centrifugal force acting on each laundry article 84 in the treating chamber 20 is proportional to the distance from the axis of rotation. Thus, along the radius of the treating chamber 20, the centrifugal force exhibited on the individual laundry articles 84 will vary. Accordingly, the closer the laundry article 84 lies to the axis of rotation, the smaller the centrifugal force acting thereon. Further, not all of the laundry articles 84 forming the laundry load 80 have the same density and/or mass. The centrifugal force applied to each laundry article 84 must be great enough to overcome the mass of the given laundry article 84 to effect satellization. To satellize all of the laundry articles 84, the treating chamber 20 must be rotated at a speed sufficient such that the centrifugal force acting on all of the laundry articles 84, regardless of radial location and mass, is greater than the gravity force acting on each of the laundry articles 84.
Once an imbalance-induced, drum excursion occurs during a cycle of operation, the user may generally interrupt or hold a cycle of operation to redistribute the laundry articles in the interior of the drum before the user resumes the cycle of operation to complete the treatment of the laundry articles, which may take additional treatment time and cause customer dissatisfaction.
The invention addresses the problem by preventing the imbalance during the rotation of the drum, which is accomplished by monitoring a speed profile of the drum and applying an acceleration profile onto the speed profile. It has been observed that the speed profile of the drum may be temporarily altered by applying the acceleration profile out of phase relative to the location of the imbalance to form a counterbalance to the imbalance already formed in the drum. This process is repeated many times during the speed profile, resulting in an essentially even distribution of the laundry about the drum. As the imbalance detection method can detect relatively small magnitude imbalances, the method creates a corresponding counterbalance before the magnitude of the imbalance can cause an excursion. The repeated formation of the relatively small counterbalances essentially distributes the laundry evenly about the drum. In an extreme example, it can be thought of as creating infinitesimally small counterbalances about the drum to create an even distribution of the laundry about the drum.
Referring to
As is illustrated, during the rotation of the drum 18, the rotational speed may not be high enough to satellize all of the laundry load 80 to the inner wall of the drum 18, resulting some laundry articles 84 tumbling and some satellized, which may form the imbalance 82. The tumbling articles may be used to form a counterbalance to the imbalance.
During the acceleration phase, the rotational speed of the drum 18 may increase with time according to the speed profile in the absence of any imbalance 82 coupled to the drum 18. Typically, such an increase is designed to be linear. However, the imbalance 82 may, depending on its magnitude, impair the control of the motor 30 to rotate the drum 18 according to a non-linear speed profile because gravity acting on the imbalance 82 may result in local acceleration and deceleration of the drum 18 attributable to the force of gravity acting on the imbalance. For example, the drum 18 may have a tendency to accelerate when the imbalance 82 is located at the right half of the drum, as viewed in
As the acceleration/deceleration attributable to the imbalance 82 happens on a per revolution of the drum basis, the rotational speed changes in the presence of the imbalance 82, and the speed profile may be represented in a profile having periodicity, instead of the designed linear profile. Under this condition, the speed profile may include multiple data such as an amplitude or frequency of the speed profile of the drum 18 having imbalance 82. The amplitude or frequency of the speed profile may be correlated to the magnitude or location of the imbalance 82 in the interior of the drum 18. The data about the speed profile may be collected by the motor torque sensor 68 for a predetermined time period to define the speed profile of the drum 18 when the drum 18 rotates in accordance with the speed profile. The data about the speed profile may be received and acted on by the controller 14 to implement a cycle of operation. For example, the controller 14 may use the data to determine an acceleration profile by control software stored in the memory 64 of the controller 14.
As illustrated, a counterbalance 86 formed from multiple pieces of laundry articles 84 may be formed substantially diametrically opposite to the imbalance 82 in the drum 18. The creation of the counterbalance 86 also tends to uniformly distribute the articles about the drum 18. While the counterbalance 86 is illustrated being formed by multiple laundry articles 84, this is for illustration only. The actual number of laundry articles can be one or more.
The counterbalancing may be performed by altering the rotational speed of the drum 18, such as by applying an acceleration profile on top of the speed profile. The acceleration profile may be determined based on the multiple data, such as frequency or amplitude, collected from the speed profile such that the acceleration profile may be approximately 180 degrees out of phase with the location of the imbalance 82 to form the counterbalance 86 opposite the imbalance 82.
For example, contrary to the behavior of speed profile of the drum 18 having the imbalance 82, the acceleration profile may be configured to decelerate the drum 18 when the imbalance 82 is located at the lower-right portion of the drum 18, as viewed in
It is further noted that the formation of the counterbalance 86 may not exactly offset the imbalance because of the size, mass and radial locations of the articles available to form the counterbalance. If the mass of the counterbalance is greater than the mass of the imbalance, then then a portion of the counterbalance may form an imbalance that is subsequently counterbalanced.
It may be noted that the acceleration phase of the speed profile is a linear function (represented as ‘reference speed profile’) that, in reality, is turned into a non-linear, periodic speed profile because of the presence of the imbalance in the drum 18. Thus, the periodic nature of the acceleration phase is indicative of the location of the imbalance. And, when applying an acceleration profile onto the speed profile to form the counterbalance, an acceleration profile that is 180 degrees out of phase with the resulting speed profile may be applied to effect a formation of the counterbalance opposite the imbalance.
The signal for the speed profile may be collected from the motor torque sensor 68, and may include multiple data such as amplitude or frequency. As illustrated, the speed profile modified by the imbalance may include a sinusoidal profile while other profiles having a periodic nature, such as a square wave profile, triangle wave profile, or sawtooth wave profile, may be also possible.
The acceleration profile may be determined from the data collected for the speed profile. The acceleration profile may be complementary to and out of phase with the speed profile to which the acceleration profile may be applied. The acceleration profile may be in the form of the sinusoidal profile as illustrated, while other profiles such as a square wave profile, triangle wave profile, or sawtooth wave profile may be also possible, depending on the shape of the speed profile. As illustrated, the sinusoidal acceleration profile may be approximately 180 degree out of phase with the speed profile. Alternatively the sinusoidal acceleration profile may be applied from 90 degrees through 270 degrees out of phase with respect to the location of the imbalance 86. The sinusoidal acceleration profile may be applied for a predetermined time period during which the imbalance 86 may be counterbalanced by the laundry articles 84 that are satellized practically diametrically opposite to the position of the imbalance 86.
The invention described herein provides a method to counterbalance the imbalance 86 in the interior of the drum 18. The method of the invention can be advantageously used in preventing the formation of the imbalance 86 by temporarily altering the speed profile of the drum 18 having the imbalance 86 in the drum 18. The speed profile may be temporarily altered by applying the acceleration profile approximately 180 degrees out of phase with respect to the location of the imbalance 86. As a result, the imbalance 86 may be counterbalanced during the acceleration of the drum 18, without interrupting or holding the rotation of the drum 18 to redistribute the laundry load 80 to fix any imbalance 86.
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.
