Abstract:
The present invention provides a system and apparatus for monitoring temperature and airflow from multiple sensors node for maintaining proper conditions within a refrigerated tractor-trailer unit or reefer. The system provides a mesh network of multiple sensors, which communicate between sensors and with a processing unit of a reefer unit for monitoring the condition of transported goods.

Description:
PRIORITY CLAIM 
     The present invention claim priority to U.S. Provisional Application No. 61/420,226, filed Dec. 6, 2010. No new matter has been added. 
    
    
     BACKGROUND OF THE PRESENT INVENTION 
     1. Field of the Present invention 
     The present invention relates to an advanced sensor architecture for use in refrigerated tractor trailer units (“reefers”). More specifically, the present invention relates to a mesh network of multiple sensors which communicate between sensors and with a processing unit of a reefer unit. 
     2. Description of Related Art 
     Heat energy can enter a closed container, like a trailer, in many ways. It can be conducted through trailer walls. It can flow around gaps in door openings or through cracked door seals. Heat can be conducted in through the trailer floor or out through the ceiling. A structural member or a steel bolt will act as a channel for heat if it passes through from outside to inside. Better reefer trailers have internal structures for rub-rails and E-tracks that are separated and insulated from the outside walls. 
     Other sources of heat are often the loads themselves. Exothermic foods such as chocolate ice cream, broccoli and beans will actually increase load temperature. 
     Mobile refrigeration units are designed to maintain, not change temperature. Reefers are not designed to chill down field loads from 100 degrees ambient temperature to 40 degrees storage temperature. They are designed to remove any increased heat and to keep product temperature stable. 
     Reefers also control humidity by condensing moisture from the air. To do these things, refrigeration units require four things: thermal integrity of the trailer to prevent the inflow of additional heat; sufficient BTU capacity to remove the expected amount of heat; sufficient airflow, measured in cubic feet per minute (cfm), to exchange the air inside a trailer about once every minute; and sufficient air velocity to move the air through the trailer and over and through the load. 
     The complex nature of reefer units creates frequent breakdowns which result in loss of products from spoilage. Recent research done by the University of Florida, in cooperation with the Florida and the U.S. Department of Agriculture, indicates that 46 percent of the drivers surveyed had loss claims, averaging one claim in a little over two years. Claims from high temperature, gases and humidity averaged more than $7,500. Yet, according to researchers, more than a third of drivers rarely or never check cargo temperatures before accepting a load, and more than half rarely or never use any recording thermometer to monitor the load in transit. 
     In theory, refrigerated loads come from temperature-controlled storage, spend no time on docks or in higher temperatures and the interior of a pre-cooled trailer maintains its temperature even when its doors are opened in the yard and the trailer is backed into its dock. In actuality, loads are often too warm when they are loaded, drivers don&#39;t shut their reefers off before opening doors and debris in the floor channels blocks airflow. 
     When a pre-cooled reefer operates with the doors open; warm, humid outside air is sucked in. The moisture hits the evaporator, which ices up. That cuts off cold airflow, while warm air fills the previously pre-cooled trailer. The same effect results when debris gets into return air passages, blocking the flow of cold air. The function of a refrigeration unit is to maintain the temperature of a load, which means removing heat from any sources, both from inside the load and outside. When cooling, the load is the warmer object, and the air surrounding the load is, or should be, cooler. That cooler air must be in contact with the load in order for it to remove heat energy. If the air does not flow then the temperature of the air in reefer unit will quickly reach the same temperature as the load. As the load warms up, so will the air. Then no cooling, not even temperature maintenance, will occur. 
     During the entire process of heating and cooling, the interior of the reefer is not actively monitored or managed. Further, all of the items within the reefer are treated the same and no record is kept for any single item being transported. 
     SUMMARY OF THE PRESENT INVENTION 
     To address the problems and limitations noted above, an apparatus for establishing a mesh network within a reefer is provided. The object of the present invention is to enable shipping companies to monitor temperature and moisture levels while the load is in transit by establishing a mesh network of sensor controls throughout a reefer unit. The accompanying drawings, which are incorporated in and constitute part of the specification, illustrate various embodiments of the present invention and together with the description, serve to explain the principles of the present invention. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a block diagram of wireless reefer sensor unit according to an embodiment of the present invention. 
         FIG. 2  is a diagram of a preferred wireless architecture according to an embodiment of the present invention. 
         FIG. 3  is a functional configuration according to an embodiment of the present invention. 
         FIG. 4  is a side view functional configuration according to an embodiment of the present invention. 
         FIG. 5  is an electrical wiring diagram of a micro-processing unit according to an embodiment of the present invention. 
         FIG. 6  is a block diagram of a sensor control unit according to an embodiment of the present invention. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     For the purposes of promoting an understanding of the principles of the present invention, reference will now be made to the embodiments illustrated in the drawings and specific language will be used to describe the same. It will nevertheless be understood that no limitation of the scope of the present invention is hereby intended and such alterations and further modifications in the illustrated devices are contemplated as would normally occur to one skilled in the art. 
     With reference now to  FIG. 1 , a block diagram of a wireless reefer sensor unit according to an embodiment of the present invention will now be discussed. As shown in  FIG. 1 , a wireless reefer sensor unit  100  preferably includes a temperature sensor  102 , preferably with a means of recording and displaying temperature, a moisture sensor  104 , a micro airflow sensor  106 , a microcontroller unit  108  and a wireless radio transceiver  110 . A plurality of wireless reefer sensor units as described in  FIG. 1  may be positioned in locations that are effected by fluctuations in temperature and air flow. 
     With reference now to  FIG. 2 , a diagram of a preferred wireless architecture according to an embodiment of the present invention will now be discussed. As shown in  FIG. 2 , a full mesh network architecture  200  is provided where each wireless node is a reefer sensor unit (RSU) as described in  FIG. 1 , and has a means of wirelessly connecting to each of the other nodes in the network. According to one preferred embodiment of the present invention, the reefer sensor units (RSU) may be positioned as shown in  FIG. 2 : the floor channels  202 , the fore bulkhead  208 , the aft bulkhead  210 , the load line  212 , the discharged air vent  206 , and the air return  204 . Preferably, each RSU node will communicate with one another and the Microprocessor Controller located in the refrigeration/heating unit  214 . 
     With reference now to  FIG. 3 , a functional configuration according to an embodiment of the present invention will now be discussed. As shown in  FIG. 3 , the rear view of the inside of a reefer trailer showing placement of all reefer sensor units within the trailer, comprising a mesh network of reefer sensor units, a stored bulk head  308 , and a nose mount refrigeration/heating unit  318 . The mesh network as shown comprises a RSU positioned in the floor channels  302 , a RSU positioned in the aft bulk head compartment  316 , a RSU positioned in the fore bulk head compartment  314 , a RSU positioned at the air discharge  310 , a RSU positioned at the air return, and at least one RSU positioned at or above the eighteen inch load line  306 . Each RSU can interrogate and communicate with any other RSU unit and the Microprocessor Controller located in the refrigeration/heating unit  312 . 
     With reference now to  FIG. 4 , a side view of a functional configuration according to an embodiment of the present invention will now be discussed. As shown in  FIG. 4 , a loaded top airflow reefer trailer unit is provided illustrating an example product stacking pattern ensuring good air circulation throughout the entire load and preferred placement of the reefer sensor units according to one embodiment of the present invention. The mesh network as shown comprises an RSU positioned in the floor channels  410 , a RSU positioned in the aft bulk head compartment  412 , an RSU positioned in the fore bulk head compartment  406 , an RSU positioned at the air discharge  404 , an RSU positioned at the air return  414 , and at least one RSU positioned at or above the eighteen inch load line  408 . Preferably, each RSU can interrogate and communicate with any other RSU unit and the microprocessor controller located in the refrigeration/heating unit  402 . The reefer sensor units in the mesh network are positioned to detect any decline in adequate air flow parameters, areas of low or high moisture outside acceptable parameters, and any temperature fluctuations throughout the trailer. The reefer sensor units will detect and report any conditions outside acceptable parameters to microcontroller unit for automatic adjustments. All sensors can be pre-programmed to take measurement, time-stamp and store data, and alert remote monitoring station to conditions outside acceptable parameters given the load data. 
     Further, the system may be configured to read and record data to and from RFID tagged items and to use the data from such items to adjust and control the necessary temperature settings. Such data from the RFID tags may be further used to determine and detect items which may not have been properly stored. Further, the data may be used to determine points in the supply chain which are consuming more energy such as warehouses which are not keeping items stored at the correct temperature. 
     With reference now to  FIG. 5 , an electrical wiring diagram of a microcontroller unit according to an embodiment of the present invention will now be discussed. A microcontroller unit  500  receives input from a charging circuit and battery cells  502 , a temperature sensor  510 , a moisture sensor  508 , a micro airflow sensor  506 , and status detect sensors  504 . The microcontroller unit  500  then assesses all the information and sends out signals to a radio transmitter/transceiver  512 , a sensor log  516 , and a remote monitoring station  520 . Data from these sensors is processed, stored, and acted upon by the microcontroller unit  500 . 
     Preferably, the reefer sensor unit of the present invention includes circuitry and digital ports to connect to existing electrical and sensor management systems of reefer trailers previously configured with embedded circuitry. In operation, a microcontroller unit  500  is preferably programmed to routinely scan the condition of each sensor to ensure operability. 
     With reference now to  FIG. 6 , it is preferred that the microcontroller unit  602  incorporates a microprocessor  604 , a real time clock  618 , a general purpose Input/Output port to support external peripheral control  608 , a Universal Synchronous/Asynchronous Receiver Transmitter (USART)  610 , a Serial Port Interface (SPI)  612 , and memory such as RAM  622 , FLASH memory  620 , and EEPROM  614  as shown. 
     Preferably, the microprocessor  604  used may be a low power, high performance, eight-bit intergrated circuit based on the Motorola HCS08 instruction set. The controller will preferably manage power and host the master date-time clock, communication scheduling and annotation of flash memory records. 
     Communication System 
     In accordance with a preferred embodiment of the present invention, the reporting may be made via a wireless connection to a satellite mode to communicate with a satellite system such as Globalstar or Orbcomm. Preferably, such a satellite device will be a device such as the Axxon, AutoTracker, or the like, or a customized Orbcomm VHF satellite GPS tracking communications device which may be adapted with Zigbee interface antenna devices to incorporate them into the overall LAN architecture of the security system; these devices include a satellite transceiver, GPS receiver, a customized Zigbee wireless antenna with a serial (Ax Tracker) or duplex (OrbComm) interface. 
     In accordance with an alternative preferred embodiment of the present invention, the reporting may also be made using a wireless system independent from the satellite system. According to this embodiment, wireless signals may be transmitted to a wireless relay, base station or the like for routing and transmission to a chosen centralized location independent from or in combination with the transmissions made from the satellite system. In accordance with this alternative embodiment, signals may also be received by the communications manager and wireless interface from such external wireless networks as well. 
     According to a preferred embodiment of the present invention, it is preferred that the wireless communications used within the present invention will be based on the Zigbee (IEEE 802.15.4) standard. This standard transmits RF signals in the 2.4 GHz ISM band and operates with low power consumption due to its relatively slower data transmission rate (128 Kpps-250 Kbps). This approach enables additional capacity and flexibility of design through an up to 255 node pico-network. Communications are simplex or duplex in design, meaning that data can be assessed in either a push or pull process. 
     As referred to above, all communications of the present invention may be designed to be duplex or simplex in nature. Further, as needs require, the processes for transmitting data to and from the present invention may be designed to be push or pull in nature. Still, further, each feature of the present invention may be made to be remotely activated and accessed from distant monitoring stations. Accordingly, data may preferably be uploaded to and downloaded from present invention as needed. For example, as detailed above, each system and subsystem of the present invention may be designed to send, receive, report and request information via the wireless and/or satellite systems so as to continually maintain and update the container systems. 
     Additional communications with the communications manager are preferably enabled via industry standard wired interfaces, with communications protocols implemented in firmware for future upgrade. These interfaces preferably will include at least two RS-322 compatible serial ports. These alternate serial ports may assist the communications manager to interface with additional remote sensors as well as other local reader/controllers such as an RFID reader or other devices. 
     Remote Monitoring 
     To support and monitor the dataflow generated by the present invention, it is preferred that users establish a centralized location to collect and analyze data. This central location or “data fusion center” would preferably consolidate all tracking signals, sensor alarms and reports generated by the monitoring systems and provide further context and links with current intelligence. 
     Preferably, such a data fusion center will receive such source information in a variety of formats such as Electronic Data Interchange, XML, E-mail, HTML and flat text files. After receiving such data, the data fusion center preferably would act to process information to identify anomalies. With this data collected and processed, analyst may calculate statistics and probability of detection models used for decision support. In short, such a data fusion center would preferably provide a consolidated source of information that could be used to assist agencies and shippers. 
     The present invention provides a real-time delivery tracking solution that solves many system wide problems in the current temperature sensitive product delivery system. By establishing a mesh network of reefer sensors, temperature fluctuations throughout the reefer trailer can be detected and the system adjusted to protect the product. The present invention enables shipping companies to improve quality control and eliminate spoilage by identifying specific problems in load and operational procedures. This level of efficiency translates directly in lower costs and better service.