Abstract:
Systems and methods for improving drying efficiency are disclosed. The systems may include a dryer a motor operatively connected to the drum and configured to cause the drum to rotate. The systems further include a controller for controlling operation of the dryer and configured to alter a drum rotation direction during a drying cycle. The methods may include, at the beginning of the drying cycle, causing the drum to rotate in a first rotation direction thereby causing the contents of the dryer to traverse along the drum centerline. In addition, causing the contents of the dryer to traverse along the drum centerline comprises reversing the rotation direction during the drying cycle. Reversing the rotation direction promotes movement of the contents within the drum in the opposite direction.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    The present application is related to U.S. patent application having Ser. No. 11/853,271 titled “Centrifugal Switch Bypass for Reverse Tumble Dryers” filed Sep. 11, 2007 and U.S. patent application having Ser. No. 12/325,219 titled “Dryer With Stationary Drying Cycle” filed Nov. 30, 2008, both of which are hereby incorporated by reference in their entirety. 
     
    
     FIELD OF INVENTION 
       [0002]    Embodiments of the present invention relate to appliances. More specifically, embodiments of the present invention relate to clothes dryers having a reverse tumbling action. 
       BACKGROUND OF THE INVENTION 
       [0003]    With conventional domestic clothes dryers, it is not uncommon to have some damp items in a load of laundry at the end of a drying cycle, especially for large loads of laundry. In addition, there is a tendency for laundry to become tangled during the drying cycle. As a result, a few items within the load of laundry may be overly dried (i.e. expose dot excessive heating) and other items may remain damp and/or wet at the end of the drying cycle. Furthermore, currently dryers utilize a unidirectional motor which cannot be reversed. 
         [0004]    There exists a need for a dryer having a drying cycle that can improve dying effectiveness. Furthermore, there exists a need for a dryer having a drying cycle that can reduce tangling of laundry during the drying cycle. 
       BRIEF DESCRIPTION OF THE INVENTION 
       [0005]    Consistent with embodiments of the present invention, systems for improving drying efficiency are disclosed. The systems include a dryer comprising a drum having a drying compartment, and a motor configured to cause the drum to rotate. The systems further include a controller for controlling operation of the dryer and operatively connected to the motor and configured to alter the rotational direction of the drum during a drying cycle. 
         [0006]    Still consistent with embodiments of the present invention, methods for improving drying efficiency are disclosed. The dryer comprises a controller operatively connected to motor operatively connected to a drum, including a baffle, in order to facilitate drum rotation. The methods comprise receiving, at the controller, an indication to start a drying cycle. At the beginning of the drying cycle the drum rotates in a first direction. The methods further include causing the contents of the dryer to traverse in a generally axial direction, that is, a direction generally parallel to the drum centerline during drum rotation. Causing the contents of the dryer to traverse in an axial direction is facilitated by configuring the baffle such that during drum rotation the baffle promotes movement of the contents within the drum in the axial direction. In addition, the drum and baffle are configured to allow the contents of the dryer to traverse axially in one direction when the drum rotates in a first rotational direction and to allow the contents of the dryer to traverse axially in the opposite direction when the drum rotates in a second rotational direction such as when the rotational direction is reversed during the drying cycle. By this arrangement reversing the rotation direction of the drum promotes movement of the contents within the drum in the opposite axial direction. 
     
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
         [0007]    Non-limiting and non-exhaustive embodiments are described with reference to the following figures, wherein like reference numerals refer to like parts throughout the various views unless otherwise specified. 
           [0008]      FIG. 1  depicts basic dryer components; 
           [0009]      FIG. 2  depicts a drive assembly for a dryer having reverse tumbling action consistent with embodiments of the invention; and 
           [0010]      FIG. 3  depicts an interior of a dryer drum consistent with embodiments of the invention. 
       
    
    
     GENERAL DESCRIPTION 
       [0011]    Reference may be made throughout this specification to “one embodiment,” “an embodiment,” “embodiments,” “an aspect,” or “aspects” meaning that a particular described feature, structure, or characteristic may be included in at least one embodiment of the present invention. Thus, usage of such phrases may refer to more than just one embodiment or aspect. In addition, the described features, structures, or characteristics may be combined in any suitable manner in one or more embodiments or aspects. Furthermore, reference to a single item may mean a single item or a plurality of items, just as reference to a plurality of items may mean a single item. Moreover, use of the term “and” when incorporated into a list is intended to imply that all the elements of the list, a single item of the list, or any combination of items in the list has been contemplated. Also note the terms “dying efficiency” and “drying effectiveness” may be used interchangeably throughout this specification. 
         [0012]    Embodiments of the present invention utilize at least one baffle located within a drum in conjunction with altering the drum&#39;s rotational direction to improve drying effectiveness. The drum rotation may be altered by changing the rotation speed and reversing the rotation direction of the drum throughout the drying cycle. The baffle within the drum is configured and positioned to improve drying efficiency by promoting movement of the contents within the drum such that the contents do not remain in a single location throughout the drying cycle. 
       DETAILED DESCRIPTION 
       [0013]    Various embodiments are described more fully below with reference to the accompanying drawings, which form a part hereof, and which show specific embodiments of the invention. However, embodiments may be implemented in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. Accordingly, the following detailed description is, therefore, not to be taken in a limiting sense. 
         [0014]    Referring now to the figures,  FIG. 1  depicts a section of a dryer  100  showing a motor  104  used to rotate a drum  102 . Motor  104  is operatively connected to drum  102  via a belt  118 . Referring now to  FIG. 2 , during operation of the motor  104  idler arms  108  and  112  in conjunction with idler pulleys  110  and  114  maintain tension on a belt  118  (shown in  FIG. 1 ). When the direction and speed of the motor is changed, thereby reversing the drum rotation and altering its rotational speed, idler arms  108  and  112  may pivot about a pivot point  106 . In addition, to help maintain a constant tension on belt  118 , a spring  116  or other connecting mechanisms may be used to connect idler arm  108  to idler arm  112 . For example, spring  116  may be replaced with a turnbuckle, a bolt, and an elastic band to create a constant tension or variable tension on belt  118 . 
         [0015]    Dryer  100  may also include a belt switch  120 . Belt switch  120  may be configured such that depressing belt switch  120  causes the drying cycle to terminate. Should belt switch  120  be depressed, motor  104  may stop rotating, a heating element (not shown) may shut down, and an alarm may sound. It is contemplated that other functions to alert a user of possible malfunctions or terminate dryer operations may occur when belt switch  120  is depressed. For example, in the event belt  118  breaks or separates from a pulley  122  attached to motor  104  or drum  102 , idler arm  112  may depress belt switch  120  causing the drying cycle to terminate and an audible alarm to sound. 
         [0016]    In other aspects of the invention, idler arms  108  and  112  may be replaced with a stretch belt. When utilizing the stretch belt, idler arms may not be needed to maintain tension on belt  118 . However, idler arm  112  may continue to be utilized as a safety for depressing a belt switch  120 . 
         [0017]    Still consistent with embodiments of the invention, moisture sensors  208  and  210  may be used to reverse dryer  100 &#39;s rotation direction. For example, if moisture sensor  210 , located near S-Baffle  202  or some other feature within drum  102 , indicates a constant moisture level for a preset amount of time, moisture sensor  210  may initiate controller  130  to reverse the rotation direction. For instance, during the drying cycle, a wet sock may come to rest against moisture sensor  210  and S-Baffle  202  due to drum rotation or other factors. Moisture sensor  210  may then send an indication to controller  130  indicating the constant moisture level. In an attempt to dislodge the wet sock, controller  130  may then cause drum  102  to reverse rotation direction. 
         [0018]    Various aspects of the invention may also include the rotation of drum  102  being altered at various times throughout the drying cycle. For instance, the drum rotation and drum speed may be altered by controller  130  at multiple times throughout the drying cycle. Controller  130  may have one or more preset routines which indicate that drum  102  may spin in a clockwise direction for a preset amount of time and reverse and rotate in a counter-clockwise direction for a preset period of time. For example, at the beginning of the drying cycle, the drum may rotate in a counter-clockwise direction for nine minutes and then rotate in the clockwise direction for five minutes during the drying cycle. After rotating in the clockwise direction for five minutes drum  102  may reverse directions again and rotate in the counter-clockwise direction for nine minutes. 
         [0019]    To reverse the rotational direction of the drum, the controller may shut down the dryer motor. The dry motor may be a reversible motor. Once the drum has stopped, the polarity on the motor is reversed to cause the motor (i.e. the drum) to reverse rotation direction. During drum reversal, an optocoupler may be used to power a relay hold up circuit. Before the drum begins to slow down in order to change rotational direction, a bypass relay may bypass a centrifugal switch thereby keeping the heating element activated while the drum reverses its rotational direction. 
         [0020]    In it contemplated that the time intervals between rotation and counter-rotation are not necessarily fixed. For example, drum  102  may rotate counter-clockwise for nine minutes, clockwise for two minutes, counter-clockwise for three minutes, clockwise for six minutes, etc. The possible combinations of drum rotation in the clockwise and counter-clockwise directions are virtually limitless. 
         [0021]    In various aspects of the invention, controller  130  may also alter the rotation speed of drum  102  according to preset drying modes. For instance, while washing delicates the drum may rotate at one speed and for drying towels or other bathroom items drum  102  may rotate at a different speed. For example, while drying delicates dryer  100  may rotate at 30 RPM. When drying more rugged items such as bath towels or athletic gear, the drum may rotate at 20 RPM. 
         [0022]    Furthermore, aspects of the invention may also include controller  130  altering the rotation speed of drum  102  during the drying cycle. For instance, at the beginning of the drying cycle, drum  102  may spin at a beginning speed. As the drying cycle progresses, drum  102 &#39;s rotation speed may increase and decrease. For example, at the beginning of the drying cycle, drum  102  may rotate at 60 RPM. At a second drying cycle stage, the rotation speed may increase to 90 RPM. At a third drying cycle stage, the rotation speed may decrease to 30 RPM. 
         [0023]    Still consistent with embodiments of the invention, drum  102 &#39;s rotation speed may increase and decrease in a linear fashion. For example, at the beginning of the drying cycle, drum  102  may rotate at 60 RPM and the rotation speed may decrease and increase in a constant manner throughout the drying cycle. 
         [0024]    Referring now to  FIG. 3 ,  FIG. 3  depicts the interior of drum  102 . Drum  102  may have a drum sidewall  204  and a drum end wall  206 . Connected to drum sidewall  204  may be an S-Baffle  202 . In addition, connected to drum sidewall  204  and drum end wall  206  may be moisture sensors  210  and  208 . 
         [0025]    During rotation of drum  102 , S-Baffle  202  promotes movement of laundry along the drum center line. S-Baffle  202  promotes movement along the drum center line via S-Baffle  202 &#39;s shape and placement within drum  102 . For instance, a plane  212  on S-Baffle  202  may be slanted such that when laundry impacts plane  212  the laundry is deflected toward the front of dryer  100 . For example, a plane  212  on S-Baffle  202  may propel the laundry toward the front of drum  102  during clockwise rotation. When drum  102 &#39;s rotation direction is reversed, plane  212  may promote movement of the laundry toward the rear of drum  102 . 
         [0026]    Moisture sensors  208  and  210  may be operatively connected to a controller (not shown). When moisture sensors  208  and  210  indicate a moisture level above a maximum moisture level, controller  130  may substantially prohibit termination of the drying cycle. Substantially preventing termination of the drying cycle means lengthening the drying cycle by a maximum preset amount of time, selected to avoid damage to the load that could result from prolonged exposure to heat. 
         [0027]    In various aspects of the invention, depending on the type of items being dried, moisture sensors  208  and  210  may extend the drying cycle for 30 minutes, one hour, etc. For example, while drying bath towels, if moisture sensors  208  and  210  indicate moisture level above the maximum moisture level, the drying cycle may be extended for 30 minutes or one hour, but no longer than 1.5 hours. If drying delicate linens and moisture sensors  208  and  210  indicate moisture level above the maximum moisture level, the drying cycle may be extended for 15 minutes or 30 minutes, but no longer than 45 minutes. 
         [0028]    Consistent with embodiments of the present invention, moisture sensors  208  and  210  may also terminate the drying cycle prematurely. If moisture sensors  208  and  210  indicate moisture levels below a minimum moisture level, controller  130  may terminate the drying cycle. For example, if delicate linens are being dried for a preset time of 45 minutes and moisture sensors  208  and  210  detect moisture levels below the minimum moisture level after 30 minutes, the drying cycle may then be terminated to save energy and prevent unnecessarily exposing the linens to excessive heat and mechanical abuse from the tumbling action of dryer  100 . 
         [0029]    Furthermore, various aspects of the invention may include altering both the rotation direction and the rotation speed during the drying cycle. For instance, during the drying cycle drum  102  may rotate clockwise at a first rotation speed and then may rotate counter-clockwise at a second rotation speed. Additionally, variations in rotation speed may occur during a single direction of rotation. For example, during the drying cycle drum  102  may begin rotating clockwise at a first rotation speed. During clockwise rotation, controller  130  may change drum  102 &#39;s rotation speed to a second rotation speed. Later during the drying cycle, controller  130  may cause drum  102  to rotate counter clockwise at a third rotation speed. 
         [0030]    S-Baffle  202  has the general S-shape depicted in  FIG. 2 , to enhance the tumbling of the clothes in the drum as the drum rotates. More specifically, the general S shape tends to impart the desired generally axial direction to the movement of the clothes load as the items tumble. With this shape, when the drum rotates in a first direction the clothes tend to move axially in a first direction as they tumble, and to move axially in the opposite direction when the direction of rotation is reversed. More specifically for the embodiment of  FIG. 2 , when the drum rotates in a clockwise direction, the clothes tend to move toward the front of the drum as they tumble, and when the drum rotates in the counterclockwise direction, the clothes tend to move toward the rear of the drum as they tumble. Other shapes that achieve such motion may be similarly employed. In addition, S-Baffle  202  may also have a radial length that differs from other baffles located in drum  102 . For instance, S-Baffle  202  may protrude inward toward the center of drum  102  further than other baffles within the drum. For example, S-Baffle  202  may be located within drum  102  with standard baffles found in dryers and S-Baffle  202  may be anywhere from an eighth of an inch to an inch to two inches longer than the standard baffle. This extended length enhances the imparting of the axial movement of the clothes during tumbling. 
         [0031]    This written description uses examples to disclose the invention, including the best mode, and also to enable any person skilled in the art to make and use the invention. The patentable scope of the invention is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they have structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal languages of the claims.