Abstract:
An RS-485 bus is directly connected to transportation refrigeration unit sensors for transmitting information from the sensors to a remote location and for controlling sensor parameters from the remote location. The GENSET associated with the transportation refrigeration unit also utilizes the RS-485 bus, in which the bus is directly connected to the GENSET sensors for bi-directional communication therewith.

Description:
RELATED APPLICATIONS 
       [0001]    This Application claims rights under 35 USC §119(e) from U.S. Application Ser. No. 61/342,129 filed Apr. 9, 2010, the contents of which are incorporated herein by reference. 
     
    
     FIELD OF THE INVENTION 
       [0002]    This invention relates to the utilization of a 485 transfer bus and more particularly to the utilization of such a bus to provide two way communications to and from transportation refrigeration unit. 
       BACKGROUND OF THE INVENTION 
       [0003]    Transportation refrigeration units are utilized in the transport of perishable goods, with the temperature and environmental controls being critical to the arrival of the perishable goods without damage or spoilage. Typical transportation refrigeration units have sensors within the units to provide data back to a central processing location so that temperature and/or humidity as well as the operating condition of refrigeration units during transportation can be monitored. 
         [0004]    Typically units such as Thermo King and the like provide an RS-232 bus. However, for each of the transportation refrigeration units there are multiple sensors that can be activated or provided to sense various conditions depending on the load. Moreover, with varying load requirements come varying requirements for the refrigeration unit itself including requirements not only for the refrigeration unit but also for the electrical generator which powers the unit. 
         [0005]    Thus, there has been a problem with the use of only the RS-232 bus to be able to provide adaptability to different loads, to be able to set sensors to different parameter levels and to be able to activate certain sensors as well as to provide control of the sensors that are activated. 
         [0006]    In the case of transportation refrigeration units, the sensors are those associated with food products. The sensors could be spoilage sensors, sensors to determine changes in temperature, and additional sensors inside the transportation refrigeration unit to monitor temperature at different places, since temperature is not necessarily uniform throughout a unit. Note, there is oftentimes a requirement to be able to add additional sensors to a single temperature sensor and there is a requirement to be able to add the sensors and control the sensors remotely. 
         [0007]    Present transportation refrigeration units today pass data through the traditional RS-232 interface. However, the RS-232 interface does not support multiport direct communications with the sensor system to permit listening in directly to each of the sensors and to query selected sensors. 
         [0008]    Also with sensors, there is a necessity to provide a control bus because it is important to be able to control the signal-to-noise ratio. This is done by adjusting sensor parameters and an RS-232 data bus does not have a signal-to-noise control capability. 
       SUMMARY OF INVENTION 
       [0009]    In order to provide for increased functionality to be able to at the very least calculate signal-to-noise ratios having to do with transportation refrigeration units, as well as to be able to provide additional sensors and to set the parameters thereof, in the subject invention an RS-485 control bus architecture is utilized to provide the ability to control sensor parameters to improve the signal-to-noise ratio. This is accomplished by fine tuning the sensors remotely. 
         [0010]    One of the objectives of the subject invention is to be able to adjust sensors inside the transportation refrigeration unit to sense temperature and other changes based on observed data. It is noted that various perishable items have different observed temperature differentials indicating spoilage. For instance, bananas need to be controlled to within plus or minus 1 degree Fahrenheit of a stable temperature in order to arrive fresh, whereas avocados do not have a critical temperature component. Other perishables might need plus or minus 10% temperature control to prevent spoilage. 
         [0011]    There is therefore a necessity to be able to change the sensor parameters based on the load and to be able to control these sensors remotely to correspond to the perishable load involved. The subject RS-485 control bus provides for a mechanism of reconfiguring perishable food sensors to correspond to the particular load involved. This is unlike the RS-232 bus because it permits direct listening into sensor outputs to be able to issue the appropriate commands. Also, the RS-485 bus allows or facilitates multiple additional sensors. 
         [0012]    In summary, an RS-485 bus is directly connected to transportation refrigeration unit sensors for transmitting information from the sensors to a remote location and for controlling sensor parameters from the remote location due to the connect sensors to RS-485 bus. GENSET associated with transportation refrigeration units utilizes the RS-485 bus directly connected to its sensors for bi-directional communication directly to the sensors. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0013]    These and other features of the subject invention will be better understood in connection with the Detailed Description, in conjunction with the Drawings, of which: 
           [0014]      FIG. 1  is a diagrammatic illustration of a temperature refrigeration unit including a container, a refrigerator and controller and a control bus that runs between the controller and GENSET sensors and refrigeration unit sensors; 
           [0015]      FIG. 2  is a listing of the type of sensors that are associated with transportation refrigeration units; 
           [0016]      FIG. 3  is a TRU Data Acquisition and Controller (TDAC) diagram describing the operation of the subject system illustrating the use of the RS-485 bus; 
           [0017]      FIG. 4  is a diagrammatic illustration of GENSET data acquisition and control scenario using a GENSET and GENSET Data Acquisition and Controller (GDAC) in which the GENSET and its sensors are controlled over an RS-485 bus; 
           [0018]      FIG. 5  is a diagrammatic illustration of a transportation refrigeration unit and TDAC module illustrating the sensing of the various parameters associated with a particular load; and, 
           [0019]      FIG. 6  is a diagrammatic illustration of a TRU Data Acquisition and Control unit coupled to a transportation refrigeration unit, again illustrating the utilization of an RS-485 bus. 
       
    
    
     DETAILED DESCRIPTION 
       [0020]    Referring now to  FIG. 1 , a TRU  10  includes a container  12 , a refrigeration unit  14  and a refrigerator controller  16 , in which the refrigeration unit is set by its controller to operate between predetermined temperature boundaries. Controller  16  is coupled via a RS-485 control bus  20  not only to sensors  22  within the container but also to sensors  24  within the generator or GENSET  26  and sensors  28  within the refrigeration unit  30 . It will be appreciated that in one embodiment there may be as many as  11  sensors in the container to monitor temperature, air flow and other parameters; whereas there may be as many as  54  sensors in the GENSET to monitor electrical parameters, fan speed and pressure in the refrigeration unit. Finally, there may be as many as  155  sensors in the refrigeration unit itself. 
         [0021]    Referring to  FIG. 2 , various of the transportation refrigeration unit sensors include for instance temperature sensors which monitor the left hand and the right hand supply air temperatures as well as return air temperature. Moreover, there may be an evaporator coil sensor or condenser coil sensor, a compressor top cap sensor and an ambient air temperature sensor. Additionally, four USDA specified spare sensors are listed that make up the temperature sensing package for the transportation refrigeration unit 
         [0022]    Other sensors can include a humidity sensor, an advanced fresh air management system plus sensor and a CO 2  gas sensor. 
         [0023]    Moreover, sensors can include compressor discharge line temperature sensors, high pressure cutout switch/discharge pressure sensors, low pressure cutout switch/suction pressure sensors, phase measuring circuits and current measuring circuits. 
         [0024]    What will be appreciated is that for transportation refrigeration units there are many different parameters that need to be monitored and controlled so that spoilage is minimized or eliminated. 
         [0025]    Referring to  FIG. 3 , a TRU Data Acquisition and Control (TDAC) block diagram is illustrated in which as illustrated at  40  carrier control information includes communication protocols and handshakes, message formats and content, error messages, diagnostic codes, command and control messages and I/F communication to other systems such as the Purfresh system. All of these control protocols are utilized to control TRU  42  through the communication of this information via TDAC module  44  coupled to TRU  42  utilizing an RS-485 connection. 
         [0026]    This information can be wirelessly transmitted to the TRU as illustrated by antenna  46  on TDAC module  44  which is connected by the RS-485 interface  50  to the TRU. Module  44  includes an internal processor and control module  52  which includes a processor, memory, bus control, device management, debug, BIST, data logging and applets. 
         [0027]    Module  44  also includes processor flash, RAM and SD memory to provide programs storage, data storage and to provide a personality module, here as illustrated at  54 . 
         [0028]    Also within TRU  42  is a GPS and cellular modem subsystem  56  that has a GSM protocol in one embodiment and a GPS module, whereas wireless RF mesh networking is provided as illustrated at  58  within this module which may include a 2.4 gigahertz/JenNet stack/Zigbee Pro Stack all operating at approximately 250 kilobits per second. 
         [0029]    Finally, there are sensor expansion and serial ports available at  60  that include RS-232 buses, analog buses; digital/SPI/CAN buses and other buses. 
         [0030]    Referring now to  FIG. 4 , a GENSET Data Acquisition and Control (GDAC) module  62  is connected to a GENSET  64  in part via an RS-484 bus. GENSET  64  in one embodiment including a GENSET controller  66  coupled to a diesel engine  68 , with the GENSET controller coupled to GDAC  62  using an RS-485 bus. The GENSET controller module is connected via GSM wireless as illustrated at  68  so that if the GDAC module is coupled to a telenostics dynamic data center, various controls can be applied to the GENSET itself. These controllers involve the use of data and a knowledge based system to improve performance. Thus for instance GENSET location and status, fuel usage, engine status and health, realtime data, real “green history”, summary reports, actionable information history, user customizable reports and a configurable web portal are supported by the RS-485 configuration. 
         [0031]    Referring to  FIG. 5 , what is shown is a TRU installation  72  in which a TRU  74  is coupled to a TDAC  76  in part through the utilization of an RS-485 bus. Here a reefer management system test is illustrated showing the type of information that is available over the RS-485 bus. 
         [0032]    Referring to  FIG. 6  the TRU Data Acquisition and Control module  76  coupled to TRU  74  is illustrated as controlling a Thermo King transportation refrigeration unit  78 , the data of  FIG. 5  being culled from the operation of this TRU. 
         [0033]    While the present invention has been described in connection with the preferred embodiments of the various figures, it is to be understood that other similar embodiments may be used or modifications or additions may be made to the described embodiment for performing the same function of the present invention without deviating therefrom. Therefore, the present invention should not be limited to any single embodiment, but rather construed in breadth and scope in accordance with the recitation of the appended claims.