Abstract:
A comfort HVAC or refrigeration system includes a remote sensor for sensing an environmental condition within a climate-controlled space and having, an associated transmitter for sending, a wireless signal to a receiver of a controller such that the controller can then responsively modulate the operation of the components of the HVAC or refrigeration system to maintain a desired condition at a specific location or locations within the-climate-controUed&#39;space. The desired condition can be, for instance, temperature, humidity and/or carbon dioxide level.

Description:
TECHNICAL FIELD 
       [0001]    This invention relates generally to comfort HVAC (heating, ventilation, air conditioning) and refrigeration systems and, more particularly, to a method and apparatus for maintaining desired parameters, such as temperature and humidity, within a climate-controlled space while using remote wireless sensors. 
       BACKGROUND OF THE INVENTION 
       [0002]    Heating, ventilation, air conditioning and refrigeration (HVAC&amp;R) systems are designed to maintain predetermined conditions in a space. These conditions are primarily related to a desired temperature range, but other conditions, such as humidity level and carbon dioxide content, for example, may be controlled as well. This is generally accomplished by the use of one or more dedicated sensors positioned within the space. 
         [0003]    Currently temperature and/or humidity sensors are installed within the space at fixed secure locations, and/or hard wired to a control that is either located within the space or outside the space. For example, in a building, the sensor may be associated with a thermostat which is typically mounted on the wall, with wiring passing to a control that responsively activates components of the HVAC system such as a furnace and an air conditioner. In a refrigerated enclosure or a container, one or more sensors are located at specific secured locations within the refrigerated container and are hard wired to a control which is normally located outside of the refrigerated space of the container. However, in either case, the location of the sensor is not necessarily the location where the temperature needs to be measured and controlled. For example, in the building, the temperature needs to be controlled in the near vicinity of a person or a number of people who ale the occupants of the climate-controlled environment. In a container, the temperature needs to be controlled in the particular portion of the space in which the cargo resides or within the cargo itself and not at the specific fixed location at which the sensors have been originally installed. These limitations can be overcome by the present invention. 
       DISCLOSURE OF THE INVENTION 
       [0004]    In accordance with the present invention, a wireless sensor or sensors are selectively positioned within a space to be conditioned or refrigerated and include a transmitter for communicating a sensed environmental condition to a receiver associated with a controller, which responsively actuates components of an HVAC&amp;R system. In this way, the one or more sensors may be selectively positioned to satisfy the comfort or thermal load requirements and provide precise control of environmental conditions at any desired location in an efficient manner. An environmental condition sensor may include, but is not limited to, a temperature sensor, a humidity sensor, a carbon dioxide sensor of a combination thereof. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0005]      FIG. 1  is a schematic illustration of a sensor and a control in accordance with the present invention. 
           [0006]      FIG. 2  is a schematic illustration of a refrigerated enclosure in accordance with the present invention. 
           [0007]      FIG. 3  is a schematic illustration of a comfort HVAC system in accordance with the present invention. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0008]      FIG. 1  shows a remote wireless sensor  11  and an associated control  12  in accordance with the present invention. The sensor  11  is designed to sense an environmental condition, such as temperature or humidity, within a space such that the control  12  can responsively operate an HVAC&amp;R system so as to maintain that condition within a predetermined range. 
         [0009]    In order to communicate the sensed condition to the control, the sensor  11  is provided with a transmitter  13 , and the control  12  is provided with a receiver  14 . The transmitter  13  and receiver  14  can be of any wireless type such as, for example, a radio frequency device. Such a wireless arrangement allows for selective placement of one or more sensors within the space to be conditioned as will now be described. 
         [0010]    As is seen in  FIG. 2 , a refrigerated enclosure  16  is provided with an associated refrigeration unit  17 . In transport applications, the refrigeration unit  17  is typically mounted on the front end of the refrigerated box  16  and provides conditioned air to the refrigerated enclosure  16  that is typically circulated over the top and through the refrigerated cargo  18 , with the air then passing along the floor, and partially along the sides, back to the refrigeration unit  17  to be re-conditioned and re-circulated into The refrigerated enclosure  16 . Rather than the one or more sensors being hard wired and positioned at specific secure locations of the refrigerated enclosure  16 , a plurality of remote wireless temperature sensors  19  are selectively located within or in the vicinity of the cargo  18 , and communicate in a wireless manner with a controller  21  that is typically positioned within the refrigeration unit  17  so as to control the temperature and/or volume of air flowing to the refrigerated enclosure  16 , in order to maintain the refrigerated cargo  18  at a temperature within a predetermined range. 
         [0011]    In this manner, the refrigerated cargo  18  is Maintained at a predetermined temperature, and over-cooling, as well as insufficient cooling, of the refrigerated cargo  18  is avoided, regardless of the position of the refrigerated cargo  18  within the refrigerated enclosure  16 . Furthermore, if the refrigeration unit  17  is capable of providing variable air volume or variable airthrow, the refrigerated cargo  18  can be kept at a sufficiently more uniform temperature in response to the feedback of the remote wireless temperature sensors  19  to the controller  21  of the refrigeration unit  19 , in order to avoid potential spoilage or loss of the product quality. Such sensor-controller communication also allows for a more efficient operation and lower energy consumption for the refrigeration unit  17 . 
         [0012]    It should be understood that that remote wireless temperature sensors  19  may be installed in addition to the primary sensors associated with the refrigeration unit  17  to provide correlation between the air temperature and airflow/airthrow supplied to the refrigerated enclosure  16  and the temperatures within the refrigerated cargo  18 , or they may be the primary and only sensors providing feedback to the control  21  of the refrigeration unit  17 . 
         [0013]    In  FIG. 3  there is shown a typical residential building  22  with two climate-controlled spaces such as rooms indicated at  23  and  24 . A comfort HVAC system  25  may include an air conditioner or heat pump typically comprising outdoor and indoor units  26  and  27 , respectively units and a furnace  28 , the latter typically installed to provide heating to the climate-controlled spaces  23  and  24 . It should be understood that although the reference is made to a residential building, other construction types, such as, for example, a commercial building, a school or a hospital, are within the scope and can benefit from the invention. The heated or cooled air is circulated by way of an indoor fan  29  through the climate-controlled spaces  23  and/or  24 , for instance, by way of respective dampers  31  and  32 . The comfort HVAC system  25 , including the dampers  31  and  32 , is controlled by a control  33  so as to maintain predetermined conditions within the rooms  23  and  24 . 
         [0014]    Rather than having thermostats hard wired at fixed locations within the room  23  and/or the room  24 , wireless sensors  34  and  36  are selectively located within the respective rooms  23  and  24  as shown. It should be understood that the numerals  34  and  36  may also represent different positions of the same wireless sensor. The sensor could, for example, be attached to an individual such as by way of a key chain or the like and, in this case, should be well insulated from the body heat, or could be a movable sensor that an individual can carry from one location to another and place it in his/her vicinity within the associated climate-controlled space. Such an arrangement allows for the control of the comfort parameters such as, for instance, temperature, humidity and carbon dioxide content, at the point of interest, i.e. where one or more persons are congregated (e.g. by way of opening and closing specific air registers or dampers within a climate-controlled space), rather than at a far end of a climate-controlled space (room) where a thermostat might be located or even prevent conditioning of the entire building. It should be understood that a single sensor may control one environmental parameter, and multiple sensors may be used to sense environmental conditions, if desired. On the other hand, a single multi-purpose sensor may control multiple environmental parameters. Further, it may be operable in association with an occupancy system such that, for example, when a person (or persons) bearing the sensor(s) has been within the room  23  for a predetermined period of time, the conditions in that room would be maintained at the desired comfortable level while the conditions in the room  24  might be allowed to rise or fall outside the comfort zone or maintained with less precision. If the person(s) then moves into the room  24  and remains there for a predetermined period of time, the controlled conditions in the two rooms could be reversed. This would occur, for instance, by selective operation of the dampers  31  and  32  as determined by the control  33  in response to the sensed condition at the location of the person(s). In this manner, by providing comfort conditions only at the desired locations, the comfort HVAC system  25  would consume the least amount of power and operate at high efficiency levels. 
         [0015]    Although described in terms of use in a refrigerated enclosure such as a refrigerated container and a residential split system, the present invention is equally applicable to similar refrigeration systems, such as truck-trailer systems, wending machines, refrigerated displays and merchandisers, and comfort HVAC systems, such as rooftops and vertically packaged systems. 
         [0016]    While the present invention has been particularly shown and described with reference to preferred and modified embodiments as illustrated in the drawings, it will be understood by one skilled in the art that various changes in detail may be made thereto without departing from the spirit and scope of the invention as defined by the claims.