Patent Publication Number: US-RE38348-E

Title: Battery assembly

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This is a divisional of U.S. application Ser. No. 08/909,907 filed Aug. 12, 1997, and now U.S. Pat. No. 5,877,703 issued Mar. 2, 1999. 
    
    
     TECHNICAL FIELD 
     The invention relates to electronic instrument enclosures that are located with utility meters outside of a building in underground enclosures. 
     DESCRIPTION OF THE BACKGROUND ART 
     In moderate climate zones, utility meters are located in subsurface enclosures in areas near residences or other dwellings. Such enclosures are referred to as “pits.” An example of such enclosure is illustrated in Haase et al., U.S. Pat. No. 1,781,280. 
     In Edwards et al., EPO Publication No. 0 252 184, meter data is transmitted from a utility meter in an underground pit to an in-ground electronic coupling circuit and then to an electronic collection unit carried by a meter reading person. Scuilli, U.S. Pat. No. 4,758,836, shows an electronic metering unit which uses the inductive coupling method of the metering unit of Edwards et al. 
     Besides inductive coupling system, radio frequency transponder systems have also been known. Examples are illustrated and described in Cerny et al., U.S. Pat. No. 5,298,894, issued Mar. 29, 1994, and assigned to the assignee of the present invention. In these systems, a receiver/transmitter, and an associated antenna are enclosed in one or more sealed enclosures which are located in a larger pit for the water meter. When the transponder is interrogated by a signal, it returns a radio signal to a collection unit, either hand-held or carried by in a vehicle, where the radio signal can then be decoded to extract the meter data. 
     A primary issue concerning all remote meter systems, whether used in pit installations or elsewhere, is their resistance to weather, and to submersion in the event that the pit fills with water. Therefore, a primary object of the invention is to provide a device that is resistant to environmental conditions in its operating environment. 
     Typically, the data storage device is powered by one or more batteries, which must also be contained in a sealed enclosure. For an example of a prior battery assembly, please refer to Karsten et al., U.S. Pat. No. 5,476,731, assigned to the assignee of the present invention. 
     Therefore, another object of the invention is to provide for battery replacement in the field without adversely affecting the environmental protection of the electronics in the assembly. 
     As with other electronic devices, there is also a desire to make the devices smaller in size, lower in the cost of manufacture, and easier to service in the field. 
     SUMMARY OF INVENTION 
     The invention is provided in an improved battery enclosure which can also be enclosed within an outer enclosure but removed, in the event that the battery must be changed, without affecting the environmental protection of the other portions of the assembly. 
     The invention provides a fully remote meter reading system with weather-resistant features that permit installation of the transponder unit in outdoor underground enclosures. 
     The invention provides a unit of reduced size and weight, and yet provides the weather resistance and operating features of prior units. 
     The invention also provides a unit having advantages in its assembly and manufacturing. 
     Other objects and advantages, besides those discussed above, will be apparent to those of ordinary skill in the art from the description of the preferred embodiment which follows. In the description, reference is made to the accompanying drawings, which form a part hereof, and which illustrate examples of the invention. Such examples, however, are not exhaustive of the various embodiments of the invention, and, therefore, reference is made to the claims which follow the description for determining the scope of the invention. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a general pictorial illustration showing the present invention in its operating environment; 
     FIG. 2 is a sectional view in elevation taken in the plane indicated by line  2 — 2  in FIG. 1; and 
     FIG. 3 is a bottom perspective view of the outer enclosure seen in FIG.  2 . 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring to FIG. 1, the invention is incorporated in a remote transponder assembly  10  located in a subsurface pit enclosure  11 . The term “transponder” shall mean electronic circuitry for receiving an interrogation or “read” signal and electronic circuitry for sending meter data signals. The signals are received and transmitted through an associated antenna. These items will be described in more detail below with respect to the preferred embodiment. 
     The pit enclosure  11  (FIG. 1) includes side walls  13 ,  14  and a lid  15  which is removable to open the enclosure for access. A bottom wall  12  is optional. The pit enclosure  11  in this embodiment is made of metal, but in other embodiments could be made of concrete or plastic. 
     The pit enclosure  11  is located along the route of water supply pipe  17 . A water meter housing  16  is connected in the water supply line  17 , using hex-head nuts  18 ,  19  which are sealed in a conventional manner against leaks at the connecting points. A water meter register  20  is mounted on top of the housing  16  and is magnetically coupled to the movements of the nutating disc in the water meter  16 . 
     The meter register  20  (FIG. 1) is preferably the Recordall™ transmitter register offered by Badger Meter, Inc., the assignee of the present invention. This unit includes an electromechanical device for generating pulses representing units of consumption as described in Strobel et al., U.S. Pat. No. 4,868,566, entitled “Flexible Piezoelectric Switch Activated Metering Pulse Generators.” The meter register  20  is electrically connected to the pit transponder assembly  10  via a cable  21 , which is preferably a “Belden 4541” shielded pair cable with drain wire. Metering pulses are transmitted from the meter register  20  to the pit transponder assembly  10 . 
     As disclosed in U.S. Pat. No. 5,298,894, cited in the Description of the Background Art, a transponder assembly  10  may communicate via electromagnetic, radio frequency waves to a handheld collection unit (not shown herein) carried by a meter reading person or a collection unit carried in a vehicle (not shown herein). The transponder assembly  10  may also be part of a networked system in which one or more transponder assemblies  10  communicate with local receiver stations which further communicates with a central data collection station. 
     In addition to different types of data collection systems, different types of meter registers can also be used, including the High Resolution Transmitter (HRT) Series, and the LMI Series from the assignee of the present invention, or other meter registers known in the art. 
     In the embodiment in FIG. 1, the transponder assembly  10  is attached to pit lid  15  through a hole  29  in the pit lid  15 . The outer enclosure  24  for the assembly includes a body with a cylindrical wall  27  closed at the bottom by bottom closure  23 , and an upper flange portion  26  leading to the threaded stem  28  that extends through the hole  29 . A cap  22  is screwed onto the stem  28  to suspend the assembly  10  from the lid  15 . The outer enclosure  24  is preferably made of a durable plastic material to insulate the electronics inside and to provide resistance to corrosion and chemical degradation from substances such as salt water, which may be encountered in harsh environments. 
     The cap  22 , which is also made of plastic, is formed with a recess having inner diameter threads  30  (FIG. 2) for mating connection with outer diameter threads  31  (FIG. 2) on stem  28 . The cap  22  also has a flat bottom side which engages a top side of the pit lid  15  and the circular flange portion  26  engages an underside of the pit lid  15  to trap a portion of the pit lid  15  between the flange portion  26  and the underside of the cap  22 . The cap  22  also has a hexagonal opening  32  through the center to receive a hex-sided anti-tamper plug  33  (FIG.  2 ). Stem  28  includes hex socket  34  to receive plug  33 . 
     Referring to FIGS. 1 and 2, the assembly  10  has three main compartments or sections inside the outer enclosure  24 . A middle compartment is formed by an inner enclosure  40 , which is typically made in two pieces, a seamless cylindrical body  41  and a disc-shaped lid  42 . The lid  42  (FIG. 3) is inserted in the open end of the body  41  and welded around an upper rim of the body  41  to seal the inner enclosure  40 . The inner enclosure  40  is preferably made of a metal such as copper, tin, or an alloy of either of these materials. The material is preferably one which is easy to form in a thin-walled enclosure, which is easy to weld and which provides a final barrier against moisture penetration, while also providing some measure of corrosion resistance. 
     Inside the inner enclosure  40  in FIG. 2 is a transponder printed circuit board (PCB)  90  in which receiving and transmitting circuitry and any necessary data storage circuits are mounted on a circuit board substrate. If the system is of the remote, mobile data collector type, the PCB  90  can be purchased from American Meter Company. If the system is of the network type, the PCB  90  can be purchased from CellNet Data Systems of San Carlos, Calif., USA. In alternative embodiments contemplated by the invention, a timed or periodic call-in period could be used such that receiver circuitry would not be necessary and only transmitter circuitry would be included on PCB  90 . 
     This PCB  90  (FIG. 2) is held down against upward movement by a support  43  having three upstanding legs  44 . The legs  44  have feet  47  tapering from wider at the top to narrower at the bottom which extend through the substrate of PCB  90 . In addition, the legs  44  extend upward to a Y-shaped horizontal member  48  with three angularly spaced parts. Two of the branches of the Y-shaped member are longer than the third branch, so that an annular flange  49  at an intersection of the three parts is eccentrically located with respect the central longitudinal axis  105  of enclosure  24 . Annular flange  49  (FIG. 2) projects upward and bears against the ceiling of enclosure  40  to space the horizontal member  48  a distance of such ceiling. The depression  39  in the lid  42  of the inner enclosure  40  is positioned in front of the annular flange  49  as seen in FIG.  2 . 
     PCB  90  is supported from below by a Y-shaped support  120  (FIG. 2) having a Y-shaped base, three extensions angling upward from the base  121  to the underside of the PCB  90 , and three arcuate collar parts for fitting around the feet  47  of the upper Y-shaped support member  43 . 
     The outer enclosure  14 , which is preferably made of plastic, to resist chemical attack, completely surrounds and encloses the metal inner enclosure  40 . The plastic is typically a modified polyphenylene oxide (PPO) material which is resilient to provide protection against unintentional impacts. The outer enclosure provides additional space  35  (FIG. 2) in the hollow stem  28  to form an upper compartment for housing an antenna  50  and an antenna support  60 . This hollow portion  35  includes a boss  36  resulting from formation of a socket  34  for receiving the anti-tamper plug  33 . Race  37  is formed between the boss  36  and the side wall of stem  28 , and this race  37  receives the antenna  50 , which is provided as a printed circuit board (PCB). Within the race  37 , stand-offs  38  project down from the ceiling to provide spacing of the printed circuit board  50  from the inside surface of the stem  28 . 
     The antenna PCB  50  is supported by a support frame  60 , having a Y-shaped base, three legs rising from the ends of base, and pins on the ends of the legs which are received in holes on the PCB  50 . The antenna support  60  also has a projection  64  (FIG. 2) extending downward from its center portion to locate the support frame  60  in a depression  39  (FIG. 2) in the lid  42  of the inner metal enclosure  40 . 
     In the present embodiment, the antenna PCB  50  is positioned slightly above the metal pit lid  15  when the transponder assembly  10  is attached to the pit lid  15 . However, in embodiments for use in pit enclosures of concrete or plastic, the transponder assembly  10  can be mounted by a mounting flange having a threaded opening similar to cap  22 , but fastened with screws underneath the pit lid  15 . In these alternative embodiments, the antenna can be positioned underneath the pit lid. The present invention could also be used in other remote transmitter and transponder assemblies, provided that power requirements for the transponder are reduced in accordance with FCC regulations. 
     Referring again to FIGS. 2 and 3, a lower compartment in the assembly houses a battery  65 . The lower compartment is formed by a base member  86  (FIG. 3) and a battery casing member  69  (FIG.  3 ). The base member  86  supports the inner enclosure  40 . Referring to FIG. 3, the base member  86  is cylindrical in shape with a closed top end and an open bottom end. The base member  86  forms a potting well  87  and wire entry port  89  where the cable  21  enters the assembly, is connected to the transponder PCB  90 , and where the connection is sealed with potting material  88  seen in FIG.  2 . As further seen in FIG. 3, a first cylindrical post  84  having a threaded hole  106  for receiving a fastener is integrally formed with the potting well  87 . Opposite the first post  84  is a second, hollow, semi-cylindrical post  85 , which forms a second injection port for potting material  88 . The two spaced apart posts  84 ,  85  are also utilized to locate the battery casing  69  when it is assembled to the base member  86 . 
     The battery casing  69  is formed to hold a single battery  65  in this embodiment. The battery  65  is connected by leads  66  to connector  68  via a battery circuit board  67 . This assembly of parts  65 - 68  is positioned in battery casing  69 , with the circuit board supported by posts  72  having pins  73  to retain and locate the circuit board  67 . The battery  65  is received in semi-cylindrical battery trough  74  in which stand-offs  75  are formed to support the battery  65  above the casing wall. A first guide channel member  76  is formed on a wall of the battery casing which extends around the circuit board  67 . A web  80 , partially visible in FIG. 3, runs perpendicular to the trough  74  along the bottom of the casing to a well  81 . The web  80  provides a place to grip the battery casing  69  with a thumb and forefinger when installing or removing the battery assembly  65 - 69  in the larger assembly  10 . The well  81  is necessary for forming another guide channel member  82 . The members  76 ,  82 , provide semi-circular channels  83  for sliding onto the posts  84 ,  85  formed in the base member  86  to thereby locate the battery casing  69 . A grease is applied to the socket  68  to prevent potting material  108  from flowing into the openings for receiving the pins  94 . 
     When assembling the battery subassembly, the battery  65  is placed in casing  69  and a sealing material  108  is filled in, around and over the battery  65  as seen in FIG.  2 . This seating material  108  is softer, more ductile and has a longer cure time than sealing material  88 . The base member  86  has a gasket  93  formed by a guard rail that traces an outline of the open side of the battery casing  69 , but is sized to fit inside the outside walls of the battery casing  69 , when it is pressed against the base member  86 . The gasket  93  is then spaced a short distance inside the walls of casing  69 . The sealing material  108  is filled in, around and over the battery  65  in the subassembly of components  69 ,  86  and is allowed to cure and solidify. It remains, however, deformable, and when the battery casing  69  and battery are installed over guard rail  93 , the guard rail  93  is pressed into the soft body of sealing material  108  and becomes embedded there. 
     As seen in FIG. 3, the gasket  93  also orients the battery casing  63  so that the 2-pin socket  68  on the battery circuit board  67  will be aligned with two pins  94  on an electrical connector  95  for making connection with the transponder PCB  90 . The pins  94  on the electrical connector  95  extend through a plastic body  109  for supporting and mounting the connector  95 . The pins  94  are received in a socket  96  mounted on PCB  90 . 
     The cable  21  with plug socket  98  is inserted and connected as shown in FIG.  2 . The cable  21  has three insulated wires  111 , one of which is shown in FIG.  2 . The three insulated wires are sheathed in a cable insulation jacket  112 . A strain relief collar  113  of metal is crimped on a cable insulation jacket  112 , and prevents a length of cable  21  from being pulled through wire entry port  89 . 
     A room temperature vulcanizing adhesive/sealant  88  is admitted through the port  85  until it fills the annular space (FIG. 2) between side wall  27  of enclosure  24  and the side wall of inner enclosure  40 . The outer enclosure  24  has an inwardly tapering shoulder  97  at the upper end of side wall  27  to block sealant from entering antenna chamber  35 . 
     Cable socket  98  is plugged into pins of connector  100  (FIG. 2) to electrically connect the cable  21  to connector  100 . Electrical connectors  95 ,  100  are preassembled with inner enclosure  40  using molded disks of epoxy adhesive. The epoxy is used to cover slots  102  in the metal enclosure body  41  to secure the plastic bodies  109 ,  110  of connectors  95 ,  100  in place and to insulate the pins from the metal enclosure body  41 . The three pins of connector  100  are aligned along an axis that is rotated 90° from an axis of alignment for the two pins of connector  95 . Similarly, socket  96  on PCB  90  is rotated 90° from an axis of alignment for socket  104  on PCB  90 . 
     This asymmetrical arrangement of the pins assures proper orientation and electrical connection of the battery casing assembly to the PCB  90  in inner enclosure  40 . In lieu of using sockets  96 .  104 , the pins could also be directly soldered to the PCB  90 . 
     After the battery casing  69  with battery  65  is assembled within casing  86 , cable  21  has been connected, and sealing operations have been completed, the bottom cover  23  (FIG. 2) is attached and fastened with a screw  25  (FIG. 2) which is received in a threaded hole  106  in post  84  (FIG.  3 ). The screw  25  has a head requiring a specific driver for inserting and removing the screw  25 , which provides tamper resistance. 
     Although the preferred embodiment utilizes a battery casing with one battery, a battery casing for two batteries and for a larger single batteries is also contemplated as being within the scope of the invention. In such an assembly, the casing may be oriented perpendicular to the position of battery  65  with respect to posts  84 ,  85 , and the battery casing may more completely fill the cavity in base member  86 . 
     This has been a description of examples of how the invention can be carried out. Those of ordinary skill in the art will recognize that various details may be modified in arriving at other detailed embodiments, and these embodiments will come within the scope of the invention. 
     Therefore, to apprise the public of the scope of the invention and the embodiments covered by the invention, the following claims are made.