Abstract:
A material drying apparatus having a sealable chamber for receipt of wet material, such as clothing, and in particular fire-fighting outfits. In this embodiment clothing placed into the chamber is dried upon the evacuation of air from the chamber wherein moisture drawn from the clothes is condensed on a condensate coil placed in the chamber. Heating coils placed around the chamber elevate the temperature to enhance condensate operation providing an energy efficient material dryer requiring no make-up air. Condensed water is purged after the drying process although provisions provide for an interim purge should excess liquid be drawn from the material.

Description:
RELATED CASES  
       [0001]    This application is a continuation in part of Ser. No. 10/035,808, filed Oct. 25, 2001. This application is related to U.S. Pat. No. 5,806,204 and U.S. Pat. No. 6,151,795. 
     
    
     
       FIELD OF THE INVENTION  
         [0002]    This invention relates to a material dryer, and in particular, to a device used for drawing moisture at moderate temperatures from heat and abrasion sensitive fabric and films.  
         BACKGROUND OF THE INVENTION  
         [0003]    There exists a large variety of materials that require a low moisture content for usage. The most common material that requires a low moisture content is clothing. For this reason, the invention embodied in this application can be used as a clothes dryer, however, the instant invention is directed to use for drying specialty materials such as the clothing worn by fire-fighters.  
           [0004]    Among specialty materials are those compositions used in hazardous materials, HAZMAT, suits and fire-fighting or bunker suits to protect the occupants from exposure to the surrounding environment. Both types of suits are very expensive and are required to be maintained in near perfect condition. For example, some HAZMAT suits are restricted to one-time use and then destroyed. Other suits may be re-used after decontamination and re-testing to standards set out in 29 CPR 1910.120. Part of the testing parameters concerns permeation factors of the outer surface. With some of the polymers used in the outer layers, temperatures of 200 degrees F. And above opens the pores in the polymer such that the suit fails the retesting. Further, the suits must be maintained at a high level of readiness for immediate use upon an emergency call.  
           [0005]    The decontamination usually involves a chemical solution or soap and water depending on the exposure to which the suit has been subjected and the particular material(s) from which the suit is constructed. The inside of the suits also have to be cleaned for reasons of hygiene. Subsequent conventional drying of the suit is necessary and may be time consuming without the use of a mechanical drying process. The length of time each suit is out of service has dictated that agencies invest in several sets of suits for the personnel to assure available protective suits in an emergency.  
           [0006]    It is generally known that the evaporation temperature of a liquid decreases as the pressure of the surrounding air decreases. Thus, water can be drawn from a material at lower temperatures in a near vacuum environment thereby expending less energy if a lower temperature can be utilized. As a result, a number of prior art devices are directed to the modification of clothes dryers which have been developed to incorporate a vacuum or vacuum like chamber. However, these devices lose efficiency in that they constantly pump air into a chamber for purposes of discharging a volume of air and water vapor out of the device by use of a vacuum pump. Such devices require additional power as the incoming air must be circulated and in most cases heated.  
           [0007]    U.S. Pat. No. 4,257,173 discloses a “no heat” clothes dryer which simply incorporates a vacuum source coupled to an exhaust port. U.S. Pat. No. 4,305,211 discloses a clothes drying chamber whereby air and moisture particles from within the chamber are discharged by creation of a suction on the chamber. U.S. Pat. No. 4,615,125 discloses yet another vacuum chamber with a perforated rotatable drum and vacuum pump which draws air and water vapor from the vacuum chamber and contained drum.  
           [0008]    U.S. Pat. No. 5,131,169 discloses a clothes dryer with a drum enclosed in a shell having a compressor to remove air and water vapor from the shell. A cyclic operation of pumping heated air into the shell and removing saturated air is employed. U.S. Pat. No. 5,430,956 discloses a clothes drying device employing a turbo engine for drawing air from a drying room and condensing the liquid thereby reducing the volume of air produced by the drying process. U.S. Pat. No. 5,459,945 discloses a vacuum assisted system for drying clothes which includes an evaporation chamber which is located inside a condensation chamber.  
           [0009]    Thus what is lacking in the art is a material drying device that will reduce the amount of time specialty suits are out of service and reduce the failure rate of decontaminated suits upon retesting.  
         SUMMARY OF THE INVENTION  
         [0010]    Accordingly, it is an object of this invention to provide a device for rapidly drying articles with a low temperature to prevent damage to the materials from which the articles are made.  
           [0011]    It is another object of this invention to provide monitoring of the material dryer by use of conductivity sensors to measure the moisture content of the material being dried. Temperature probes are used to measure various temperatures and pressure sensors to measure pressure inside the chamber. Sensors can also be used to report the moisture content which is indicative of the amount of drying that has occurred allowing the consumer to remove material before complete drying, if preferred.  
           [0012]    Another object of the present invention is to provide a material dryer based upon the drawing of a partial vacuum on a sealed chamber with a condensate coil placed within the chamber for use in drawing moisture from clothing placed within the chamber.  
           [0013]    Another object of the present invention is to provide unitary portable device that can be moved about during use and moved to a storage space when not in use.  
           [0014]    In summary of the operation, the interior environment of the material dryer is partially evacuated by use of a vacuum pump which causes the evaporating temperature of water contained within the material to be lower than the temperature at atmospheric pressure. As a result, liquid evaporates into the chamber in the form of water vapor.  
           [0015]    Other objects and advantages of this invention will become apparent from the following description taken in conjunction with the accompanying drawings wherein are set forth, by way of illustration and example, certain embodiments of this invention. The drawings constitute a part of this specification and include exemplary embodiments of the present invention and illustrate various objects and features thereof.  
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0016]    [0016]FIG. 1 is a front plane of the instant invention;  
         [0017]    [0017]FIG. 2 is a top plane view of the instant invention;  
         [0018]    [0018]FIG. 3 is a side plane view of the instant invention;  
         [0019]    [0019]FIG. 4 is a side view partially in section;  
         [0020]    [0020]FIG. 5 is an exploded perspective view of the doors of the instant invention; and  
         [0021]    [0021]FIG. 6 is a perspective view, partially in section, of a door of the instant invention.  
     
    
     DETAILED DESCRIPTION  
       [0022]    Referring to FIG. 1, the mobile upright vacuum dryer  10  is illustrated. The dryer is of such a size and weight to be manually portable. To aid in mobility, the housing  11  may be mounted on a set of wheels  12 . The housing  11  has front  13 , back  14 , opposite side walls  15 ,  16  and a top  17  to enclose the mechanical components of the dryer. As shown, the housing  11  supports drying chambers  18  formed by large planar doors  19  and  20  which have a hermetic seal about their contiguous peripheries. The doors have opposite vertical edges  22 ,  23  and tops  24 , 25 . The doors  19  and  20  have hinges  26  and  27  along one vertical edge and a latch mechanism  28  and  29  on the opposite vertical edge.  
         [0023]    The doors  19  and  20  are mounted on opposite sides of a vertical center platen  30 . The platen  30  is hollow and contains components of the drying mechanism. As shown in FIG. 5, the platen  30  contains two separate drying elements in back-to-back arrangement forming two drying chambers  18 . Each of these drying elements have identical components which cooperate with each door to form two identical drying chambers  18 . These two chambers allow a complete suit of a jacket and a pair of trousers to be cleaned at the same time. The platen  30  supports the hinges  26  and  27  for the doors  19  and  20 .  
         [0024]    As shown in FIG. 4, the housing  11  contains a vacuum pump  31  capable of sustaining a negative pressure in the chambers  18 . The pump  31  draws a negative pressure in the water collection tank  32  which is connected to the drying chambers  18  through drain line  33  and plenum chamber  36  to lower ambient pressure in the chambers below atmospheric pressure.  
         [0025]    Each of the doors  19  and  20  have an open inner door frame  39  attached to the outer door and securing the margin of a thin impervious membrane  40 . The open frame allows air to pass through the interior of the doors. The impervious membrane  40  is sealed to the outer door and inner door frame to form a closed compartment. As the pressure is reduced in the platen  30  the membrane  40  is forced into a hermetic seal with the solid periphery  41  of the perforated plate  34  because of the atmospheric pressure acting through the open inner door frame. In this manner, the area between the membrane  40  and the perforated plate  34  is subjected to a negative atmospheric pressure.  
         [0026]    The suits to be dried are placed in this area of one or both doors. Each door has a hangar  42  or other type fastener for temporarily suspending the suit in place. The bottom of the doors may have a similar device  43  for securing the bottom of the material.  
         [0027]    Drain line  33  is connected to the perforated plate  34  through a strainer  35 . The vacuum line has solenoids  37  to control pressure and flow from the system. The tank is normally emptied after a drying cycle but has the capability of being pumped through the operation of a solenoid  37  and evacuation pump  38  during a cycle.  
         [0028]    The chambers  18  may be heated by routing compressed fluid through the material dryer housing  11  having a chamber  28  mounted horizontally within the housing  11 . The chamber  28  is hermetically sealed defining an interior  14  and an exterior  16 . The interior  14  is fluidly coupled to a vacuum pump  18  capable of a drawdown vacuum of approximately 28 inches Hg. The vacuum pump  18  operates initially to withdraw air from the chamber through exhaust check valve  19  for maintaining a low pressure environment during the drying cycle with minimum pump operation. In the preferred embodiment, the air is drawn through an internal collection tank  31  through check valve  19  and delivered to a second collection tank  30  for holding and eventual discharge to drain. The second collection tank  30  may allow an overflow to drain, or include a solenoid  32  for purging the collected water to drain. The second collection tank  30  providing a ready source of fluid for creation of a water seal for operation of vacuum pump  18 .  
         [0029]    The interior  14  of the chamber  12  is accessible through a door  20  hingedly coupled to one end of the housing  10  and maintaining a pressure seal to the chamber  12  when closed. A paddle assembly  22 , extending substantially along the longitudinal length of the chamber  12 , is used to rotate the positioning of clothes placed within the chamber. The paddle assures the clothing contacts the inner surface of the chamber in such a way as to enhance heat transfer through the sidewall of the chamber which is heated along the exterior surface  16  of the chamber.  
         [0030]    The chamber may be heated by an electric coil, utilize hot water preheater lines or the hot fluid line  24  as provided by a compressor system. The pressurized fluid is directed through an expansion valve before being directed through a condensate coil  28 . The condensate coil  28  condenses moisture from clothing placed within the chamber with the condensed moisture collected in an internal collection tank  31 . The condensate is held until the drying cycle is complete, or if full during the cycle, purged by vacuum pump  18  through check valve  19  to collection tank  30 . A set of cooling coils  36  may be routed from the condenser  28  and through the collection tank so as to provide cooling action for the vacuum pump  18  without the system consuming more energy. The condensate in the collection tank is relatively cool due to its inner action with the cold condenser coil  28  and will also provide cooling action. The cooling action extends the life of the vacuum pump and increases the overall efficiency of the system.  
         [0031]    Sensors  38  are available for determining the relative humidity within the chamber, pressure of drying chamber and temperature for operation of the compressor cycle and temperature control providing operation for only the time needed to complete a drying cycle.  
         [0032]    In operation, wet clothing is placed into the chamber  12  through door  20  wherein the vacuum pump  18  draws down the environment within the chamber  12  in about one minute. The compressor  26  then becomes operational in a format similar to a conventional air conditioner with the condensate coils  28  placed within the chamber  12 . The compressor pressurizes freon or the like refrigerant material to approximately 265 psi at a temperature of about 220 F. Instead of being used directly, the high pressure liquid from the compressor may be passed through a hot water preheating tank. The preheating tank water may then be used to heat the chamber exterior. The pressurized fluid is drawn through an expansion valve before placement through condensate coils  28 . The condensate coils  28  draw the moisture out of the clothes wherein the condensate liquid drains into the collection tank  31 . In this manner, 30 pounds of water can be evaporated in approximately 30 minutes, the system utilizing between 30,000 and 60,000 BTU&#39;s per hour. Sensors  38  may be used to monitor the time of operation or automatically determine the length of operation by determining moisture content, pressure and temperature of the chamber.  
         [0033]    Referring now to FIGS. 2 and 3, the material dryer device of the instant invention consists of a housing  10  sized to support the operating components of the system including a cylindrically shaped chamber  12  mounted horizontally within the housing  10 . The chamber  12  is hermetically sealed defining an interior  14  coated with teflon or the like non-stick coating material and an exterior  16 . A rear cage end plate  50  is positioned at the back of the chamber  12  for positioning of clothing placed within the chamber. The chamber includes pusher bars or paddles  22  for movement of the clothing around the chamber. The paddles  22  are coupled to a drive shaft support structure  52  held by drive shaft  54 . The drive shaft  54  is rotated by a timing belt and pulley assembly having pulleys  58  coupled together by belt  60 . The lower pulley  58  is rotated by drive motor  62 . The paddles  22  assure clothing contact with the inner surface  14  of the chamber  12  allowing the clothing to enhance heat transfer through the sidewall of the chamber.  
         [0034]    A centrifugal fan  64  allows for circulation of water vapor through the chamber and past condensate coils  28 . The fan  64  is driven by a fan motor  66  supported by back plate  70 . Alternatively the fan  64  can be driven by the paddle motor  62  by use of an additional pulley or modification of the pulley into a fan shape. The condensate coils are enclosed in a shroud  72  causing direction flow of the circulation air past the coils  28 .  
         [0035]    The interior  14  of the chamber  12  is accessible through a door  20  hingedly coupled to one end of the housing  10  along a front door end plate  74  and maintaining a pressure seal to the chamber  12  when closed. The door includes a handle  76  for ease of access. The front of the chamber includes a front cage end plate  78  which is operatively associated with the inner surface of the door  20  for securely positioning the clothes within the chamber. For example, a fire-fighter pants may be hung to dry in one chamber and the coat may be hung to dry in the second chamber.  
         [0036]    The interior of the chamber is fluidly coupled to a vacuum pump  18  capable of a drawdown vacuum of approximately 28 inches Hg. The vacuum pump is water sealed with a water inlet  80  drawn through strainer  82  and controlled by inlet solenoid  84 . The vacuum pump  18  operates initially to withdraw air from the chamber through exhaust check valve  19  and associated piping  86  for maintaining a low pressure environment during the drying cycle. The vacuum pump exhausts air through the air silencer  87  out of outlet  93 . The pump includes a trap  89  to further seal as well as prevent back flow of water discharged to the drain  91 .  
         [0037]    The chamber may be heated by an electric coil or utilize hot water preheater lines  90  provided by the compressor system  92  wherein the compressor  92  operates at a pressure between 250 and 280 psi. The pressurized fluid is directed through the hot water preheating tank  94  by input pipe  96  through a coiled wrap  98  wherein the input temperature to the compressor at exit pipe  100  is between 220 and 250 F. The heated water is transferred by pump  102  from tank  94  through preheater lines  90  which engage at least a portion of the chamber. The pressurized refrigerant from the compressor  92  is then directed through precooling coils  106  and into expansion valve  108  as it is introduced into the condensate coils  28 . Low pressure refrigerant  110  is returned to the compressor motor  92 . Condensed moisture is collected along the bottom of the condensate shroud  72  and directed through solenoid valve  112  and into water collector tank  114 . The solenoid valve  112  is used to maintain a vacuum in the chamber until the condensate is ready to flow into the water collector tank  114 . The water collector tank is purged by a dump valve  118  when the drying cycle is complete, should excess water be present in the collection tank during the drying cycle.  
         [0038]    As further illustrated in FIG. 3, the door includes a view area  120  and a solenoid operated latch opener  122  which allows access to the chamber only when the vacuum is removed. The door is mounted along hinge  124  providing a pivotal opening. The chamber heating coil  90  is placed around a portion of the chamber and in particular the area that the wet clothes will contact during rotation. Control panel  126  provides operational control of the system.  
         [0039]    [0039]FIG. 4 depicts a conveyor belt means  150  depicted along a portion of interior surface  152  of the chamber. In this embodiment, the conveyor belt consists of a continuous flexible belt  154  placed over rollers  156  wherein at least one of the rollers  156  is rotated by an electric motor to cause rotation of the belt. The belt may include paddles  158  to assist is transferring material along a portion of interior surface  152  along directional arrow  160 . This embodiment has a particular application for clothing as the belt  154  causes the clothing to maintain a close proximity to the interior surface which, as previously described, allows heat transfer into the clothing to provide heat of vaporization. The entry area  162  may be enlarged to accommodate the type of material circulated wherein paddle  158 ′ provides an enlarged grasp of the material for placement into the entry area  162 . The conveyor assembly  150  can be supported by brackets  164  and  166 . Bracket  164  may be made adjustable to accommodate various size loads.  
         [0040]    It is to be understood that while we have illustrated and described certain forms of my invention, it is not to be limited to the specific forms or arrangement of parts herein described and shown. It will be apparent to those skilled in the art that various changes may be made without departing from the scope of the invention and the invention is not to be considered limited to what is shown in the drawings and described in the specification.