Abstract:
A vacuum assisted dryer for accelerated drying of clothing generally comprises a fixed frame, a rotatable drum within the fixed frame for holding and tumbling clothing within a vacuum sealable interior space, a vacuum pump fixedly attached to the drum and a power delivery system for communicating electrical power from the fixed frame to the vacuum source on the drum. The power delivery system comprises a slip ring assembly about a spindle utilized to maintain the drum upon its axis of rotation inside the fixed frame. A plurality of heating pads are provided about the interior of the drum to facilitate drying of the clothing. A blower assembly evacuates to a conventional dryer vent moist air exhausted from the vacuum pump.

Description:
FIELD OF THE INVENTION 
     The present invention relates to clothes dryers. More particularly, the invention relates to a clothes dryer having a vacuum pump integral therewith to create sub-atmospheric pressures within the drum, thereby facilitating the drying of clothing and/or reducing the energy costs associated therewith. 
     BACKGROUND OF THE INVENTION 
     The desire for time and energy conservation has led to many useful developments of household appliances. In particular, a clothes dryer with an integral vacuum source has been proven to be more energy efficient that a conventional clothes dryer. A directly proportional relationship between temperature and pressure allows the evaporation temperature of the water in the clothing to be reduced as barometric pressure within the dryer is decreased. This phenomenon provides many advantages, including reduced drying times and temperatures as well as less damage to clothing. 
     In the past, others have taken advantage of this phenomenon in an attempt to produce a more efficient clothes dryer. For example, U.S. Pat. No. 5,724,750 issued Mar. 10, 1998 to Burress (“Burress”) discloses a clothes dryer with infrared heating and vacuum drying capabilities in which a stationary vacuum pump is capable of reducing the vacuum pressure inside the drum to a sub-atmospheric pressure. Likewise, U.S. Pat. No. 4,057,907 issued Nov. 15, 1777 to Rapino et al. (“Rapino”) details an apparatus having a vacuum pump that reduces the air pressure within a chamber, while a microwave emitter excites the water molecules. The apparatus of Burress and Rapino, however, each employ a rotating shaft and/or bearing assembly at their interface between internal regions of atmospheric and sub-atmospheric pressure. 
     Unfortunately, Applicant has found that the embodiments exemplified by the prior art are extremely difficult to implement. In order to obtain the tight seal necessary for maintaining the apparatus&#39; internal vacuum, a soft bushing material, such as rubber or the like, must be utilized. Such a soft material, however, quickly wears, ultimately resulting in disintegration of the seal. On the other hand, hard materials that are impervious to wear are highly susceptible to tiny vacuum leaks, which in turn destroy the object of the invention. 
     It is therefore an overriding object of the present invention to provide a clothes dryer that incorporates vacuum assistance without the disadvantages inherent in the prior art. It is a further object of the present invention to provide such a clothes dryer that eliminates the need for a sealed bearing or rotating shaft extended between regions of atmospheric and sub-atmospheric pressure, thereby increasing the reliability of the appliance. Finally, it is an object of the present invention to provide such a clothes dryer that is economical to manufacture. 
     SUMMARY OF THE INVENTION 
     In accordance with the foregoing objects, the present invention—a vacuum assisted dryer for accelerated drying of clothing—generally comprises a fixed frame, a rotatable drum within the fixed frame for holding and tumbling clothing within a vacuum sealable interior space, a vacuum source fixedly attached to the drum and a power delivery system for communicating electrical power from the fixed frame to the vacuum source on the drum. Preferably, the vacuum source comprises a vacuum pump and the power delivery system comprises a slip ring assembly about a spindle utilized to maintain the drum upon its axis of rotation inside the fixed frame. 
     In at least one embodiment, a plurality of heating pads are provided about the interior of the drum for imparting increased temperature to the clothing held therein, thereby further facilitating drying of the clothing. The heating pads may be conveniently located within paddles conventionally placed for the tumbling of clothing and may be powered through the same slip ring assembly as powers the vacuum source. A lint screen is also preferably interposed the vacuum source and the interior space of the drum, thereby preventing harm to the vacuum source from lint and the like. 
     The vacuum source exhausts to the interior space of the fixed frame, where moist air may be evacuated from the system with a blower assembly. The blower assembly maintains airflow from without the frame, about the interior of the frame and into and out of a duct to a conventional household dryer vent. 
     A vacuum relief for relieving vacuum pressure from within the drum is also preferably provided. Such a vacuum relief may comprises a valve in fluid communication with the interior space of the drum. In particular, Applicant has found suitable the use of a stopcock-type valve. 
     Finally, many other features, objects and advantages of the present invention will be apparent to those of ordinary skill in the relevant arts, especially in light of the foregoing discussions and the following drawings, exemplary detailed description and appended claims. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Although the scope of the present invention is much broader than any particular embodiment, a detailed description of the preferred embodiment follows together with illustrative figures, wherein like reference numerals refer to like components, and wherein: 
     FIG. 1 shows, in a left side cross-sectional view taken through line  1 — 1  of FIG. 2, the vacuum assisted clothing dryer of the present invention; 
     FIG. 2 shows, in a top cross-sectional view taken through line  2 — 2  of FIG. 1, the dryer of FIG. 1; 
     FIG. 3 shows, in a front elevational cross-sectional view taken through line  3 — 3  of FIG. 1, the dryer of FIG. 1; and 
     FIG. 4 shows, in a top cross-sectional view taken through line  4 — 4  of FIG. 1; details of the drive mechanism and blower assembly of the dryer of FIG.  1 . 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Although those of ordinary skill in the art will readily recognize many alternative embodiments, especially in light of the illustrations provided herein, this detailed description is exemplary of the preferred embodiment of the present invention, the scope of which is limited only by the claims appended hereto. 
     Referring now to the figures, the clothes dryer  10  of the present invention is shown to generally comprise a drum  20  rotatably enclosed within a fixed housing  11 . A vacuum pump  36  is utilized to reduce the atmospheric pressure within an interior space  28  of the drum  20 , thereby facilitating the drying of clothing held therein. As will be better understood further herein, the vacuum pump  36  is fixedly attached to and rotates with the drum  20 , which eliminates the requirement for vacuum sealed bearings and the like for communication of vacuum pressure to the interior space  28  of the drum  20 . This limitation eliminated, the clothes dryer  10  of the present invention is adapted to utilize principles of vacuum assisted drying without the high maintenance costs associated with the prior art. 
     As typical of currently available clothes dryers, the clothes dryer  10  of the present invention comprises a drum support system  45  for rotatably supporting the drum  20  within the fixed housing  11 . In particular, a plurality of rollers  46  are provided upon which the drum  20  rests. Additionally, however, provision is made in the present invention for maintaining the drum  20  on its axis of rotation. As shown in FIGS. 1 and 2, a vacuum door  22  through the front end  21  of the drum  20  is centrally fitted with a spherical bearing  25  for engaging a socket  16  at the distal end of a support arm  24  extending from an access door  13  through the front panel  12  of the fixed housing  11 . Similarly, a spindle  34  extending from the rear end  33  of the drum  20  engages a bearing  35  fixedly attached to the interior face of the rear panel  17  of the fixed housing  11 . As will be appreciated by those of ordinary skill in the art, the spherical bearing  25  engages the socket  16  in the axis of rotation of the drum  20 . Likewise, the spindle  34  engages the bearing  35  in the same axis of rotation, thereby cooperating with the spherical bearing  25  and socket  16  combination to retain the drum  20  within its axis of rotation upon the drum support system  45 . In this manner, as will be better understood further herein, delivery of electrical power from the fixed housing  11  to the rotating drum  20  is facilitated. 
     As previously discussed, a vacuum pump  36  is utilized to reduce the atmospheric pressure within the interior space  28  of the drum  20 . As also previously discussed, it is critical to the present invention to avoid sealed bearings, rotating shafts or the like between regions of subatmospheric atmospheric and pressure inside and outside, respectively, of the drum  20 . To this end, the vacuum pump  26  is dependently affixed directly to the drum  20  and rotates therewith. As particularly shown in FIG. 1, the vacuum pump  36  comprises a vacuum inlet  37  in fluid communication with the interior space  28  of the drum  20  through a provided vacuum line  39 . Preferably, the vacuum line  39  terminates in an exterior pocket  26  at the front end  21  of the drum  20 . In this manner, a lint filter  27  may be interposed the interior space  28  and the vacuum line  39  to the vacuum pump  36 , thereby preventing the introduction to the vacuum pump  36  of lint and/or other foreign objects. 
     Because, contrary to currently available vacuum assisted clothes dryers, the vacuum pump  36  of the present invention is directly affixed to the rotating drum  20 , it is necessary to deliver electrical power from the fixed housing  11  to the drum  20  for operation of the vacuum pump  36 . To this end, a power delivery system is implemented between a power source  41  (which my simply comprise the switched power from a conventional power cord  51  and electrical plug  52 ) on the fixed housing  11  and the drum  20 . According to the preferred embodiment of the present invention, a slip ring assembly  42  is implemented about the spindle  34  extending between the rear end  33  of the drum  20  and the fixed housing  11 . As is known to those of ordinary skill in the art, such a slip ring assembly  42  generally comprises a system of brushes  43  and rings  44  through which electrical power may be conveyed to a rotating object such as the drum  20 . Exemplary of the slip ring assemblies suitable for implementation of the present invention are those slip assemblies commercially available from the Airflyte Electronics Company of Bayonne, N.J. Because the rotating drum  20  is maintained in its axis of rotation as previously described, power delivery through the slip ring assembly  42  is easily within the ability of one of ordinary still in the art. 
     As in currently available clothes dryers, it is desirable to provide heat to the interior space  28  of the rotating drum  20  to facilitate drying of clothing held therein. Unlike currently available clothes dryers, however, the clothes dryer  10  of the present invention contemplates no airflow to or from the interior space  28  of the rotating drum  20  other than the vacuum pressure communicated through the vacuum line  39  from the vacuum pump  36 . As a result, the preferred embodiment of the present invention comprises a plurality of heating elements  30  distributed within the interior space  28 . Although those of ordinary skill in the art will recognize the many alternatives available, Applicant has found it convenient to locate the heating elements  30  on the interior faces of paddles  29  provided for tumbling of the clothing held within the interior space  28 . 
     While those of ordinary skill in the art will recognize the many substantial equivalents, Applicant has found suitable for implementation of the present invention the silicon rubber heater products commercially available from Watlow Columbia, Inc. of Columbia, Mo. Those products provide a reliable low-power source of heat at a temperature appropriate for use within the clothes dryer  10  with minimal risk for heat damage to the clothing held therein. As also will appreciated by those of ordinary skill in the art, the slip ring assembly  42  is readily adaptable for delivery of electrical power from the power source  41  to the heating elements  30 . 
     As is also typical of currently available clothes dryers, the clothes dryer  10  of the present invention must contend with the moisture removed from the drying clothing. In the present invention, however, the moisture evaporated from the drying clothing is removed from the interior space  28  of the rotating drum  20  through the vacuum pump  36 . In particular, an exhaust  38  from the vacuum pump  36  discharges water vapor into the interior of the fixed housing  11 . As a result, the preferred embodiment of the present invention comprises an exhaust blower  49  adapted to force air from within the fixed housing  11  through an exhaust duct  50 , which is preferably adapted for interface with a conventional household dryer vent. To ensure adequate air flow through the exhaust duct  50  for removal of the moist air within the fixed housing  11  an air intake grill  18  is preferably provided in the rear panel  17  of the fixed housing  11 , thereby ensuring a continuous volume of airflow. Additionally, in the preferred embodiment of the present invention, the exhaust blower  49  is operated by an electric drive motor  47 , which also preferably interfaces with and operates the drive assembly  48  rotating the drum  20 . 
     In order to ensure that the vacuum seal  23  about the vacuum door  22  may be broken for access to the interior space  28  of the drum  20 , a vacuum release  31  is preferably provided integral with the drum  20 . As will be appreciated by those of ordinary skill in the art, a valve  32 , which may be a stopcock valve, can economically perform this function. The user may then open the access door  13  by pulling the door  13  about its hinge  15  by a conventionally provided handle  14 . The support arm  24  is also hinged to the front panel  12  of the fixed housing  11  such that the vacuum release  31  may be accessed prior to opening of the vacuum door  22 . 
     While the foregoing description is exemplary of the preferred embodiment of the present invention, those of ordinary skill in the relevant arts will recognize the many variations, alterations, modifications, substitutions and the like as are readily possible, especially in light of this description, the accompanying drawings and claims drawn thereto. For example, conventional leveling glides  19  may be provided as shown in the figures. Likewise, the clothes dryer  12  of the present invention may be provided with an automatic shut-off switch integral with the access door  13  through the fixed housing  11  as well as a timer for conventional shut-off of the dryer. Additionally, those of ordinary skill in the art will recognize that it may be desirable to provide a counterweight  40  opposite the spindle  34  from the vacuum pump  36  for insuring balanced rotation of the drum  20  upon the drum support system  45 . In any case, because the scope of the present invention is much broader than any particular embodiment, the foregoing detailed description should not be construed as a limitation of the scope of the present invention, which is limited only by the claims appended hereto.