Abstract:
The present invention is directed to a convective thermal unit. The convective thermal unit has the conventional blower that directs ambient air to a heating element, the heating element heats the air and the heated air is directed into a conduit. The conduit directs the heated air into a receiving unit like a blanket positioned over a patient. A difference between the prior art and the present invention is the incorporation of a shape memory polymer and/or alloy material into the conduit to ensure the conduit does not contact the ground when the convective thermal unit is not being used or not providing the desired thermal energy.

Description:
FIELD OF THE INVENTION 
       [0001]    The present invention is directed to controlling a position of a hose. 
       BACKGROUND OF THE INVENTION 
       [0002]    In U.S. Pat. No. 5,747,993, Jacobson et al. wrote about controlling a hose&#39;s position. In particular, Jacobson et al. wrote, “Disposed on one side of [a] bar . . . is a strip . . . of shape memory alloy which has the capability of changing its shape upon the application of external heat or electric current (which generates internal heat) to some other shape and then assuming the original shape when cooled or electric current is removed and the heat dissipates. Example of such shape memory alloy is nitonol comprised of about 50 percent nickel and 50 percent titanium. The bar . . . is made of a laterally flexible material such as ceramic, metal or plastic, so that when the shape memory alloy strip . . . is caused to change shape, such as contract along its length, the bar will be caused to bend . . . . 
         [0003]    In this embodiment, two flexible tubes . . . are anchored respectively on bases . . . . The free ends of the tubes are positioned to mate together in a colinear fashion to seal the inside of the tubes from the outside when the tubes are undeflected. An access port . . . is formed in the tube . . . to allow introduction of fluid to the inside of the tubes. Of course, such access could be provided through the other tube . . . or through the bases . . . . Strips of shape memory alloy are disposed on the upper sides of the tubes . . . and are selectively heated by a current source to cause the tubes to deflect or bend upwardly . . . . When such deflection occurs, the ends of the tubes . . . are exposed to allow escape of fluid which has been introduced into the insides of the tubes . . . . When current to the strips of shape memory alloy is terminated so that the strips cool, the strips return to their original shape causing the tubes to deflect back to their original colinear position to again seal the inside of the tubes from the outside and prevent further outflow of fluid.” 
         [0004]    As described above, shape memory alloys have been used in association with hoses. The shape memory alloys have not, however, been used to control (a) the position of a hose to prevent contact with the ground and/or (b) fluid turbulence in the hoses. 
       SUMMARY OF THE INVENTION 
       [0005]    The present invention is directed to a convective thermal unit. The convective thermal unit has a conventional blower and a heating element. The conventional blower directs ambient air to the heating element. The heating element heats the air and the heated air is directed into a conduit. The conduit directs the heated air into a receiving unit, for example, a blanket positioned over a patient. A difference between the prior art and the present invention is the incorporation of a shape memory polymer and/or alloy material into the conduit to ensure the conduit does not contact the ground when the convective thermal unit is not being used and/or not providing a minimum desired thermal energy. 
     
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
         [0006]    The figures and the descriptions set forth in this document are examples of the present invention and not limit the breadth and scope of the present invention. 
           [0007]      FIG. 1  illustrates a fluid blanket warming system having a convective thermal unit and a blanket unit. 
           [0008]      FIG. 2  illustrates a cross-sectional view of the convective thermal unit. 
           [0009]      FIG. 3  illustrates a cross-sectional view of a portion of a conduit of the convective thermal unit interconnected to the blanket unit. 
           [0010]      FIG. 4  illustrates a view of  FIG. 3  taken along the lines  4 - 4 . 
           [0011]      FIG. 5  illustrates an electrical schematic of one embodiment of the convective thermal unit. 
           [0012]      FIG. 6  illustrates a portion of the conduit having the shape memory polymer and/or alloy positioned on the exterior surface of the conduit. 
           [0013]      FIG. 7  illustrates a portion of the conduit having the shape memory polymer and/or alloy positioned in the interior surface of the conduit. 
           [0014]      FIG. 8  illustrates a portion of the conduit having the shape memory polymer and/or alloy embedded in the material of the conduit. 
           [0015]      FIG. 9  illustrates the present invention with the conduit in a compressed position. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0016]    The present invention can be directed to a fluid blanket warming system  2  having a convective thermal unit  100  and a blanket unit  4 . An example of a convective thermal unit  100  is sold by Gaymar Industries, Inc. under the THERMACARE trademark. Other examples of convective thermal units  100  include and are not limited to Azirant&#39;s Model 505 Temperature Management Unit and Model 750 Temperature Management Unit. Each one of these convective thermal units  100  takes ambient air and heats the ambient air to a desired temperature. The heated air at a desired temperature is directed into a hose  8 . From the hose  8 , the heated air is directed into the convective blanket  4  that disperses the heated air toward a patient. 
         [0017]    An example of the blanket unit  4  is sold by Gaymar Industries, Inc. Examples of such thermal blankets are disclosed in  Augustine Medical, Inc. v. Gaymar Indus., Inc.,  181 F.3d 1291, 50 USPQ2d 1900 (Fed. Cir. 1999). In that decision, the Federal Circuit wrote, “[Gaymar&#39;s convective] blankets feature an inflatable quilt-like structure. The [Gaymar] blankets attach two sheets of the same amount of flexible, lightweight material around their periphery and at various spots along their surfaces. In operation, heated air flows onto a patient&#39;s body from holes in the undersurface of [Gaymar&#39;s] blankets, but the blankets do not form a self-supporting or Quonset hut-like structure. Instead, [Gaymar&#39;s] blankets lie flat when inflated on a flat surface and rest substantially on a patient when in use. Gaymar began selling forced-air blankets in March 1992.” The blanket unit  4  is sometimes referred to as a thermal blanket, inflatable blanket or air blanket and can be subjectively configured to address substantially all or selected portions of a patient&#39;s body. The blanket unit  4  can be configured with seams and can have air slits or holes on the underside to deliver the fluid such as heated air or other gases to the patient when inflated. Generally, the blanket unit  4  provides an air plenum of approximately a hollow core for receiving the heated air and distributing it to the patient&#39;s body. Sometimes, the air blanket is divided, however, into segments or conduits to assist in erecting the air blanket as a canopy across the patient&#39;s body. The specific form of the blanket as it is adapted to a portion of the patient&#39;s body can be a feature of the present invention and numerous different examples exist and are well known by persons of skill in this field. Alternative embodiments can have the blanket positioned below the patient and/or to a patient&#39;s side. Thus, the blanket shown in  FIG. 1  is for schematic purposes only and does not represent any limitation to the air blankets or thermal blankets that can be utilized in the present invention. 
         [0018]    The flexible conduit  8  is usually formed of a flexible plastic material that can be corrugated and/or straight, and has a first coupler  10  at one end of the conduit configuration, and a second coupler  12  at the other end of the conduit configuration. A heat source  14  includes a heater housing or cabinet  16  that can be mounted for portability with wheels at the bottom. The upper portion of the housing  16  supports a console  18  with operator temperature controls  20 . 
         [0019]    Referring to  FIG. 2 , the console  18  includes an inlet port  22  with an optional filter  24  that allows ambient air to be drawn into the cavity of the console  18 . A blower unit  26  creates a positive pressure to direct the ambient air to a heater unit  28 . In the embodiment of  FIG. 2 , ambient air is being used as the heated fluid for application to the thermal blanket  4 . It is possible, however, to provide other gases, if desired. Various configurations of blower scroll compressor, fans, etc. can be used to provide a positive air pressure. Likewise, the heater unit can also have different configurations than the resistance heater coils shown. 
         [0020]    Downstream of the heater unit  28 , a second gas filter  30  can be positioned next to a coupler  32  on the console  18 . The coupler  32  connects the conduit  8  to the console  18 . The second filter  30  provides extra filtration but could be eliminated, if desired. The coupler  32  is mounted on the console  18 , and the first coupler  10  on the flexible conduit  8  can be removably connected to coupler  32 . 
         [0021]    A control circuit  34  is connected, respectively, to the blower unit  26 , the heater unit  28 , and a first temperature sensor unit  36 . In a first embodiment, the first temperature sensor unit  36  can be mounted within a housing in the form of the second coupler  12 , as seen in  FIGS. 3 and 4 , near the heater  28 , in the blanket  4 , in the hose  8 , or near the first coupler  10 . 
         [0022]    A second temperature sensor unit  38  can also be mounted on the housing of the second coupler  12 , near the first coupler  10 , in the blanket  4 , in the hose  8 , or near the heater  28  and connected to the control circuit  34  to provide a backup or redundancy for safety purposes, as will be subsequently described. 
         [0023]    As shown in  FIG. 2 , the second sensor unit  38  can have an exterior electrical connector line  40  that can be mounted by plug into a receptacle on the exterior of the console housing  18 . Also, as shown in  FIGS. 3 and 4 , the first sensor unit  36  is connected to an electrical connector line  42  that can travel along an interior of the flexible conduit  8 . As can be appreciated, the electrical connector line  40  can also be mounted to extend along the interior of the flexible conduit  8  and, if desired, they can be fastened or adhered to the internal surface of the conduit  8 . As shown in  FIG. 2 , the connector line  42  from the first sensor unit  36  can connect with an appropriate plug or receptacle in the coupler  32  on the console  18  for connection with the control circuit  34 . 
         [0024]    By providing the first sensor  36  and the second sensor  38  in the second coupler  12 , the temperature of the heated air, as it is delivered to the thermal blanket  4 , can be measured. Any bends in the flexible conduit  8  that may effect a temperature drop, may occur upstream of the second coupler  12  and heat loss from the flexible conduit  8  will be accounted for. 
         [0025]    The first sensor unit  36  and the sensor unit  38  may be any electrical or electronic device for temperature sensing, such as a thermal couple, thermistor, resistive temperature device (RTD), semiconductor diodejunction, or integrated circuit temperature sensor with and without integrated controller or signal conditioner. 
         [0026]    Referring to  FIG. 5 , one possible schematic form of a control circuit is disclosed. Other forms of temperature control circuits can be used, as can be appreciated by a person of skill in this field. The specific control circuit  34  incorporates a proportional controller that includes an alarm system to permit a servo-controlling of the warmed air to a preset temperature level that will be set by the operator or user controls  20  on the housing of the console  18 . In this schematic, the user control temperature setting  80  is connected to a power supply  82  through a reference voltage circuit  84  which also provides excitation current for the first and second sensor units  36  and  38 . The reference voltage circuit  84  can divide and buffer the power source  82  on the control circuit. By providing two separate sensors  36  and  38 , there is a redundancy in the system, and the control circuit  34  can thereby also sense the air temperature through the second thermistor or sensor unit  38 , located in proximity to the first sensor unit  36  or thermistor to thereby provide a backup for any over temperature condition. As a safety feature of this control circuit, any over temperature sensed by the second sensor  38  or under temperature sensed by either the second sensor  38  or the first sensor  36  or the opening of an over temperature thermostat  86 , which can be located in the heater housing or console  18 , can turn off the blanket warming system. Thus, any of these conditions of an over temperature or an under temperature will indicate a problem and can be utilized to automatically shut off the power to the heater unit  28  and the blower  26  and to also further activate audible and visual alarms in the alarm circuit  88 . 
         [0027]    The first temperature sensor  36  amplifies the sensed voltage that is proportional to the air temperature adjacent a thermal blanket that is receiving the delivered heated air. This temperature signal is amplified in a first temperature sensor amplifier  90 . The amplified temperature signal is subtracted from a set point temperature from the user control temperature  80  by a differential amplifier or a difference amplifier circuit  92 . The resulting output difference signal is provided to a proportional control circuit  94 , and this different signal is compared to a triangular wave that is generated to provide a pulse width modulated (PWM) signal whose duty cycle is proportional to the difference in the output temperature and the set point temperature provided by the user control temperature  80 . This PWM signal is then applied to a solid state power switch circuit  98  through an optical isolator  96 . The power switch circuit  98  delivers appropriate pulses to the heater unit  100 . 
         [0028]    An alarm detection circuit includes under temperature comparator  102 , under temperature comparator  104 , and over temperature comparator  106 . The output of these comparators  102 ,  104 , and  106  are output together and inverted to be coupled to a reset input of a latch circuit  108 . Additionally, the voltage across the thermostat  86  is also applied to the latch reset through an optical isolator  110 . If either the first sensor thermistor  36  or the second sensor thermistor  38  senses a very low temperature, which may occur in the case of an open sensor or the second sensor  38  senses an over temperature, or if the thermostat  86  itself mechanically breaks or opens, the latch circuit  108  is reset and opens a second solid state power switch circuit  112  that is also optically isolated by an optical isolator  114 . The power switch circuit  112  is in series with the heat control power switch circuit  98 , and the power switch  112  controls power to the blower unit  116 , as well as the heater  100 , and has the capacity of shutting down the entire warming system until this alarm condition is corrected, and the warming system is reset by turning off the power and turning the power back on. The thermostat  86  is in series with both of these solid state power switches  112  and  98  and can positively interrupt power to both the heater unit  100  and the blower unit  116 . The output of the latch circuit  108  can also turn on a transistor to activate both audible and visual alarms in an alarm circuit  88 . 
         [0029]    While applicants have described one embodiment of a control circuit, the embodiments of the present invention can also be operated with alternative control circuits. 
       Shape Memory Alloys/Polymers 
       [0030]    Shape memory polymers are polymers whose qualities have been altered to give them dynamic shape “memory” properties. Using thermal stimuli, shape memory polymers can exhibit a radical change from a rigid polymer to a very elastic state, and then back to a rigid state again. In its elastic state, it will recover its “memory” shape if left unrestrained. However, while pliable it can be stretched, folded or otherwise conformed to other shapes, tolerating up to 200% elongation. While manipulated, the shape memory polymer can be cooled and therefore returned to a rigid state, maintaining its manipulated shape indefinitely. This manipulation process can be repeated many times without degradation, and manufacturers can tailor most polymers with shape memory properties. An example of this polymer can be obtained from Cornerstone Research Group, Inc. of Dayton, Ohio. 
         [0031]    A shape memory alloy is capable of remembering a previously memorized shape. It has to be deformed in its low temperature phase Martensite and subsequently heated to the high temperature phase Austenite by heated air. The alloy generates a high force during the phase transformation. The shape change is not restricted to just pure bending. A suitable actuation mode has proved to be the linear contraction of a straight wire actuator. An example of such alloy includes and is not limited to NiTi (Nickel—Titanium), CuZnAl, CuAlNi, and nitonol. 
         [0032]    The shape memory polymer and/or alloy can be in any desired shape—including and not limited to a ribbon shape, a spiral shape, a spring shape or combinations thereof. The polymer and/or alloy can have various widths, lengths, thicknesses, treatment conditions and surfaces. The shape, size and condition depend on the desired application. 
         [0033]    For the present invention, the shape memory polymer and/or alloy  110  attaches to the hose  8  so when the heated air passes through the hose  8  the thermal energy from the heated air contacts the shape memory polymer and/or alloy. The shape memory polymer and/or alloy  110  can be positioned on the exterior surface of the hose  8  as illustrated at  FIG. 6 , on the interior surface of the hose  8  as illustrated at  FIG. 7 , embedded in the material that forms the hose  8  as illustrated at  FIG. 8 , and combinations thereof. The shape memory polymer and/or alloy  110  just has to be effected by the thermal energy of the heated air passing through the conduit  8 . 
       A FIRST EMBODIMENT OF THE INVENTION 
       [0034]    A point of the application is that the shape memory polymer and/or alloy  110  assists with hose  8  management by ensuring that the hose  8  is “short” and off the ground when the hose  8  is not (a) in use and (b) connected to a blanket. When the convective blower  100  is off and at normal room temperature, the shape memory polymer and/or alloy  110  with the hose  8  are in a shortened geometry as illustrated in  FIG. 9 . As soon as the thermal energy from the heated air is applied by switching on the blower  26  (and the heated air&#39;s thermal energy is a certain predetermined temperature), the shape memory polymer and/or alloy  110  and the hose  8  extend to its “trained” length, and may be connected to a convective warming blanket  4 . Once the convective warmer  100  is switched off, the hose  8  reverts to its shortened length, and will not trail on the ground where it can pick up dirt and germs thereby constituting a potential infection control hazard. 
       A SECOND EMBODIMENT OF THE INVENTION 
       [0035]    In another embodiment, a different phase of Nitinol having a “superelastic phase” can be used to realize a spiral coiled spine. In this embodiment, the nitonol is compressed and short in the relaxed position. It may be elongated to the required length by pulling against the restoring spring force and connecting the hose  8  to the blanket  4 . An external linkage mechanism could be used to maintain the hose in the extended position. 
         [0036]    Those skilled in the art will appreciate that various adaptations and modifications of the just-described preferred embodiment can be configured without departing from the scope and spirit of the invention. Therefore, it is to be understood that, within the scope of the appended claims, the invention may be practiced other than as specifically described herein.