Patent Publication Number: US-2006010997-A1

Title: Weather resistant automatic meter reading unit

Description:
This application claims the benefit under 35 USC 119(e) of provisional application No. 60/234,328, filed Sep. 22, 2000. 
    
    
     BACKGROUND OF THE INVENTION  
      1. Field of the Invention  
      This invention relates to the field of automatic meter reading units, AMR units, particularly to such units having replaceable battery packs.  
      2. Brief Description of the Prior Art  
      Currently, the most common method used by utility providers to determine the quantity of electricity, gas and water utility product used by a residential customer services is to read manually each customers&#39; meter. Most of the meters are mechanical. The flow of electricity, water or gas induces a disk to rotate. That rotation forces a set of gears to scroll, which mechanically displays the usage. The staff reading the meters walks from residence to residence, writes down the current consumption showing on the meter, and inputs the information into a billing computer, which generates the individual bills mailed to the customers.  
      A network, a one way SSDS (spread spectrum direct sequence) network for minimizing the life cycle cost of the system, has been proposed to provide a valid alternative to conventional meter reading and existing AMR technologies. That network consists of a large number of transmitters connected to the meters, transmitting in SSDS packets the readings of the utility consumption; a network of SSDS receivers, each receiver monitoring tens of thousands of transmitters, obtaining the transmitted data packets, compressing the SSDS modulation and storing the data; and a network control center, which collects the data from the receivers via a dial-up line or any low cost communication means, stores the data in protected database, and prepares it for billing. The network transmitters use a single PCB design, a novel BPSK modulator, low-cost frequency reference, and printed low cost antennae including the matching circuits.  
      Residential meters, such as utility meters for use with such a network, operate with transmitters having batteries, which must be replaced periodically. Water or moisture, which can produce corrosion, enter the meter box and reach the printed circuit board (PCB) located there, is a problem associated with battery replacement. With the present invention, battery replacement is made faster and safer without water penetration to the PCB or the metal contacts.  
     SUMMARY OF THE INVENTION  
      It is an object of this invention that the battery cells not be assembled in the same chamber with the printed circuit board or index mechanism in order to prevent water entry to the area of the transmitter and index electronics during the process of replacing the batteries or while maintaining the index mechanism.  
      It is another object of this invention to provide a meter reading unit in which battery replacement requires removing the securing plastic seals, removing the screws holding a transparent front cover, replacing the battery pack, reinstalling the screws and seals, and injecting silicon grease to the electric contact seal to avoid corrosion.  
      It is yet another object of this invention that the battery pack be protected against any unauthorized access without first removing two front plastic access seals, securing screws and a transparent cover to access the battery pack.  
      In realizing these objects and advantages a weather resistant automatic meter reading unit according to this invention includes a chassis divided into chambers; a first chamber containing a printed circuit board having a first terminal for connection to an electrical power source; and a second chamber sealed from the first chamber, sized to contain and hold batteries, having a second terminal electrically connectable to the batteries, moveable relative to the chassis, adapted to complete an electrical connection between the first terminal and second terminal as the second chamber moves relative to the first chamber, and releasably fixed to the chassis.  
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
      Eighteen figures have been selected to illustrate a preferred embodiment of the invention.  
       FIG. 1  is a front view of a gas meter assembly having an automatic meter reading unit installed.  
       FIG. 2  is a top front view of the assembly of  FIG. 1 .  
       FIG. 3  is a side view of the assembly of  FIG. 1 .  
       FIGS. 4 and 5  are isometric views of the assembly of  FIGS. 1-3 .  
       FIG. 6  is a photographic reproduction in perspective of the automatic meter reading unit.  
       FIG. 7  is a front view of the automatic meter reading unit.  
       FIG. 8  is a cross section taken at plane  8 - 8  of  FIG. 7 .  
       FIG. 9  is a cross section taken at plane  9 - 9  of  FIG. 7 .  
       FIG. 10  is a cross section taken at plane  10 - 10  of  FIG. 7 .  
       FIG. 11  is a portion of the cross section shown in  FIG. 9 .  
       FIGS. 12 and 16  are isometric views of the battery pack portion of the automatic meter reading unit.  
       FIGS. 13, 14  and  15  are end, front and bottom views of the battery pack, respectively.  
       FIG. 17  is an isometric view of the battery pack case with the batteries and end cover removed.  
       FIG. 18  is an isometric view of the battery pack showing spring metal contacts adjacent the box, the end cover, batteries and battery case mutually spaced apart. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT  
      Referring first to  FIGS. 1-5 , a residential utility meter reading unit  10  according to the present invention includes a box  12  containing mechanical components for producing an indication of the magnitude and rate of use of a utility product such as gas, water or electricity; a transmitter unit  14  mounted on the top of the box at its front; a battery pack  16  fixed to the transmitter unit; and an index mechanism  18  located at the front face of the transmitter having a series of dials  20 , each having a rotating indicator pointing to a printed gradated scale representing the amount of consumed product and the current rate of its use by the residential customer.  
       FIG. 6  shows the transmitter unit  14  having its transparent cover, face plate and attaching screws removed to expose the index mechanism  18 , which in this case is suited for use on a gas meter, and battery pack  16 , removed from its slot  22  on the chassis front  24 . In the assembled condition, the battery pack is guided for travel along slot  22  by fitting sliders  26 ,  28 , located at the upper and lower edges of the pack, into rails  30 ,  32 , formed integrally on the upper and lower edges of the chassis front. The battery pack is closed at its outer surface by a cover  34 . Electric contact between the battery terminals and metal rivet contacts  36 ,  38 , carried on the transmitter PCB, is completed when the leg  40  of the battery pack completes its travel to the lower, inner end of slot  22 .  
      The battery pack  16  is completely sealed against moisture and the ambient environment due to its enclosing cover  42 , end cover  34  and silicon grease, injected between the main enclosure of the chassis and battery pack at the greaser point  44  (best seen in  FIG. 7 ).  
      Referring next to  FIGS. 7-11 , the transmitter unit is enclosed by rear cover  46  and front cover  48 , which covers overlap and are sealed mutually by a seal  49 , preferably a glued room temperature vulcanized rubber applied by a dispensing process in the manufacturing plant where the meter is assembled. A portion of the front cover defines a chamber  50  occupied by the rotating indicators  20  and the gears  52  that drive the indicators of the index mechanism  18 . A transparent cover  54  covers the face of the index mechanism, and a face plate  56 , is secured to the rear cover  46  by attachment screws  58 - 64 . The cover  54  and face plate  56  overlap the slot  22  into which the leg  40  of the battery pack is inserted, thereby securing the battery pack and preventing its removal except by removing two front plastic access seals, the screws and removing the cover and face plate. The attachment screws  58 - 64  engage screw threads formed in the rear cover  46 .  
      The rear cover  46  is formed with multiple shoulders  64 , and the front cover  48  is formed with similar shoulders  66 , adjacent and facing the shoulders  64 . Located between the shoulders  64  and  66  and held in position on the shoulders, is the PCB  68  of the transmitter unit  14 . The PCB supports metal rivet contacts  36 ,  38 , which electrically connect the battery terminals to the PCB when the leg  40  of the battery pack  16  is fully inserted into the slot  22 . A seal  70 , fitted within a well  72  in the front cover below the transparent cover  54 , seals the index unit and transmitter unit from the environment.  
       FIG. 8  shows two batteries cells  80 ,  82  standing upright in the battery pack, which inn that figure is held in place in its operating position under the transparent cover  54 .  FIG. 18  shows two electric contacts strips  84 ,  86  preferably formed of spring metal and located at the lower end of the leg  40 , each strip adapted to contact a metal rivet contact  36 ,  38  on the PCB when the battery pack is fully inserted in slot  22 , thereby completing an electric connection between the battery cells and the PCB. The PCB  68  is separated physically from the index mechanism  18 .  
      With the present invention, whenever it is necessary to replace the battery cells, the replacement requires only removing the securing plastic seals, removing the screws holding the transparent front cover, replacing the battery pack, reinstalling the screws and seals, and injecting silicon grease to the electric contact seal to avoid corrosion.  
      Although the form of the invention shown and described here constitutes the preferred embodiment of the invention, it is not intended to illustrate all possible forms of the invention. Words used here are words of description rather than of limitation. Various changes in the form of the invention may be made without departing from the spirit and scope of the invention as disclosed.