TRANSMITTER SET FOR AN UNDERGROUND PUBLIC SERVICES METER INSTALLATION
FIELD OF THE INVENTION The invention refers to housings of electronic instruments that are located with meters of public services outside a building with underground housings. DESCRIPTION OF THE PREVIOUS TECHNIQUE In areas of moderate climate, utility meters are located in underground shelters in areas near residences or other housing. These accommodations are called "pits". An example of the aforementioned housings is illustrated in U.S. Patent No. 1,781,289 to Haase and co-inventors. In EPW Publication Number 0 252 184 of Edwards and co-inventors, the meter data is transmitted from a utility meter in an underground pit to an underground electronic coupling circuit and then to an electronic pick-up unit that has a person taking the reading of the meter. U.S. Patent Serial Number 4,758,836 to Scuilli and co-inventors shows an electronic measuring unit using the inductive coupling method of the Edwards measurement unit and co-inventors. In addition to inductive coupling systems, radio frequency transponder systems have also been known. Examples are illustrated and described in U.S. Patent Serial Number 5,298,894 to Cerny and co-inventors, issued March 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 that are located in a larger pit for the water meter. When the transponder is interrogated by a signal, a radio signal is returned to a collection unit, either portable or installed in a vehicle, where the radio signal can then be decoded to extract the data from the meter. A main concern over all remote meter systems, whether they are used in pit facilities or elsewhere, is their resistance to weather, and to submersion in the event that the pits are filled with water. Therefore, a main object of the invention is to provide a device that is resistant to environmental conditions in its operating environment. Commonly, the data storage device is energized by one or more batteries, which must also be contained in a sealed housing. For an example of a prior art battery pack, please refer to the United States Patent Serial Number 5,476,731 to Katsten and co-inventors, assigned to the assignee of the present invention. Therefore, another object of the invention is to provide a battery replacement in the field without adversely affecting the environmental protection of the electronic components in the assembly. As with other electronic devices, you also want to reduce the size of the devices, reduce the cost of manufacturing and make the service easier in the field. BRIEF DESCRIPTION OF THE INVENTION The invention is provided in an assembly having an internal housing and an external housing for providing double-walled protection to the electronic components of the transponder in the assembly. The outer housing is made of a material to resist chemical attack, while the inner housing is provided to resist penetration of moisture. Both housings are sealed to provide an assembly that can be used in underground facilities or other remote sites that require weather resistant transponder arrays. The invention further provides an improved battery housing that can also be enclosed in the outer housing but can be removed in the event that the battery needs to be replaced., without affecting the environmental protection of the other portions of the set. The invention provides a remote meter reading system with weather resistant characteristics that allow the installation of the transponder unit in underground underground housings. The transponder unit may be mounted in the underground housings in a variety of different ways. The unit may have a portion projecting upwardly through the cover of a pit housing or may be mounted behind a non-metallic cover to a pit housing. The invention provides a unit of reduced size and weight, and still provides the weather resistance and operating characteristics of the previous units. The invention also provides a transponder unit which has advantages in its assembly and manufacture. Other objects and advantages, apart from those mentioned above, will be apparent to those skilled in the art from the description of the preferred embodiment presented below. In the description, reference is made to the accompanying drawings, which form a part thereof, and which illustrate examples of the invention. However, said examples are not exhaustive of the various embodiments of the invention, and, therefore, reference is made to the claims that follow the description to determine the scope of the invention. BRIEF DESCRIPTION OF THE INVENTION OF THE DIAMETERS FIG. 1 is a general pictorial application showing the present invention in its operating environment.; Figure 2 is a sectional elevation view taken in the plane indicated by line 2-2 in Figure 1; Figure 3 is an exploded perspective view of portions of the assembly of Figure 2;
Figure 3A is an exploded perspective view of other portions of the assembly of Figure 2; Figure 4 is a detail cut-away view taken in the plane indicated by line 4-4 in Figure 2; Figure 5 is a detail cut-away view taken in the plane indicated by line 5-5 in Figure 2; Figure 6 is a detail cut-away view taken in the plane indicated by line 6-6 in Figure 2; Figure 7 is a detail cut-away view taken in the plane indicated by line 7-7 in Figure 2; Figure 8 is a bottom perspective view of the external housing shown in Figure 2. DETAILED DESCRIPTION OF THE PREFERRED MODALITY With reference to Figure 1, the invention is incorporated into a remote transponder assembly 10 located in an underground pit housing 11. The term "transponder" shall mean electronic circuits to receive an interrogation signal or
"reading" and electronic circuits to send data signals from the meter. The signals are received and transmitted through an associated antenna. These articles will be described in more detail below with respect to the preferred embodiment. The pit housing 11 (Figure 1) includes side walls
13, 14 and a cover 15 that can be removed to open the housing to gain access. A lower wall 12 is optional. The pit housing 11 in this embodiment is made of metal, but in other embodiments it could be made of concrete or plastic. The pit housing 11 is located along the route of the water supply pipe 17. A water meter housing 16 is connected to the water supply line 17, using hexagonal head nuts 18, 19 which are sealed in a conventional manner against leakage at the connection points. A register of the water meter 20 is mounted on the upper part of the housing 16 and is magnetically coupled to the movements of the nutating disk in the water meter 16. The register of the meter 20 (Figure 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 consumption units as described in U.S. Patent Serial Number 4,868,566 to Strobel and co-inventors, entitled "Measurement Pulse Generators Activated by Piezo-Electric Switch". The meter register 20 is electrically connected to the trough transponder wings 10 via a cable 21, which is preferably a "Belden 4541" shielded pair cable with drain cable. The measurement pulses are transmitted from the register of the meter 20 to the transponder assembly of the pit 10. As described in United States Patent Serial Number 5,298,894, cited in the Prior Art Description, a transponder assembly 10 may be communicated via electromagnetic radio frequency waves to a portable pickup unit (not shown herein) carried by a person in charge of taking readings from the meter or a collection unit in a vehicle (not shown herein). ). The transponder assembly 10 may also be part of a network system in which one or more transponder sets 10 communicate with one or more local receiving / transmitting stations, which in turn communicate with a data collection station. central. In addition to different types of data collection systems, different types of meter records may also be used, including the High Resolution Transmitter Series (H RT), and the LM I Series of the assignee of the present invention, or other records. of meters known in the art. In the embodiment in Figure 1, the transponder set
is attached to the lid of the pit 15 through a hole 29 in the lid of the pit 15. The outer housing 24 for the assembly includes a body with a cylindrical wall 27 closed in the lower part by the lower closure 23, and a top flange portion 26 going to a threaded rod 28 extending through hole 29. A cap 22 is screwed to the rod 28 to suspend the assembly 10 of the lid 15. The outer housing 24 is preferably made from a Durable plastic material to isolate the electronic components inside and provide resistance to corrosion and chemical degradation of substances such as salt water, which can be found in harsh environments. The lid 22, which is also made of plastic, is formed with a groove having internal diameter threads 30 (Figure 2) for connection to the external diameter threads 31 (Figure 2) in the rod 28. The lid 22 also has a flat bottom side engaging an upper side of the pit lid 15 and the circular flange portion 26 engages a bottom side of the pit lid 15 to trap a portion of the pit lid 15 between the portion of flange 26 and the underside of cover 22. Cover 22 also has a hexagonal opening 32 through the center to receive a hexagonal violation plug 33 (Figure 2). The rod 28 includes a hexagonal receptacle 34 for receiving the plug 33. With reference to Figures 1 and 2, the assembly 10 has three main compartments or sections within the outer housing 24. A middle compartment is formed by an internal housing 40, which it is commonly formed in two pieces, a cylindrical body 41 and a disc-shaped cover 42. The cover 42 (Figure 3) is inserted into the open end of the body 41 and is welded around an upper flange of the body 41 for sealing the inner housing 40. The inner housing 40 is preferably made of a metal such as copper, brass, or an alloy of any of these materials. Preferably, the material is one that is easy to form into a thin-walled housing, that is easy to weld and that provides a final barrier against moisture penetration, while also providing a measure of corrosion resistance. Inside the inner housing 40 in Figure 2 there is a printed circuit board of transponder 90 (PCB) in which all the transmission and reception circuits are mounted as well as all the necessary data storage circuits in a substrate of the board. circuit. If the system is of the mobile, remote data collector type, the printed circuit board 90 can be purchased from the American Meter Company. If the system is of the network type, the printed circuit board 90 can be purchased from CellNet Data Systems of San Carlos, California, United States of America. In alternative embodiments contemplated by the invention, a periodic or timed call period could be used so that the receiver circuits would not be necessary and only transmitter circuits would be included in the printed circuit board 90. This printed circuit board 90 (FIG. ) is held down against upward movement by a support 43 having three vertical legs 44. The legs 44 have feet 47 that taper from the widest in the upper to the narrowest in the lower part extending through the substrate of the printed circuit board 90. In addition, the legs 44 extend upward to a Y-shaped horizontal member 48 (Figure 7) with three angularly spaced portions. Two of the shunts 45 (Figures 3A and 7) of the Y-shaped member are longer than the third shunt 46 (Figures 3A and 7) so that an annular flange 49 (Figure 7) at an intersection of the three parts is located eccentrically with respect to the central longitudinal axis 105 of the housing 24. The annular flange 49 (Figures 2 and 3A) projects upwards and is supported against the roof of the housing 40 to separate the horizontal member 48 a distance from said roof. The depression 39 in the cover 42 of the inner housing 40 is positioned in front of the annular flange 49 as shown in Figure 2. The printed circuit board 90 is supported from below by a Y-shaped support 120 (Figure 2) which has a base in the form of Y 121 (Figure 3A), three extensions 122 that form an upward angle of the base 121 to the underside of the printed circuit board 90, and three arcuate collar parts 123 to fit around the feet 47 of the upper Y-shaped support member 43. The outer housing 24, which is preferably made of plastic, to resist chemical attack, completely surrounds and houses the inner metal housing 40. The plastic is commonly a modified polyphenylene oxide (PPO) material that is elastic to provide protection against unintentional impacts. The outer housing provides an additional space 35 (Figure 2) in the hollow rod 28 to form an upper compartment for housing an antenna 50 and an antenna support 60. This hollow portion 35 includes a rim 36 resulting from the formation of a receptacle 34 to receive the plug against rapes 33. The race 37 is formed between the rim 36 and the side wall of the rod 28, and this race 37 receives the antenna 50, which is provided as a printed circuit board. In run 37, spacers 38. are projected down from the roof to provide separation of printed circuit board 50 from the inner surface of the rod 28. With reference to Figures 5 and 6, the printed circuit board of the antenna 50 is formed by a conductive circuit path 52, placed on a ring-shaped substrate 53 (surrounding the flange 36) of material commonly used in circuit boards. One end of the circuit path 52 originates through hole 57 and travels in an arc of about 330 ° around the substrate 53. The opposite end of the path of the circuit 52 is fused into a capacitor bearing 54a, which is positioned opposite the capacitor bearing 54b on the underside of the substrate 53. This bearing 54b connects through the circuit path 55, 56, which connects through hole 59 to provide a frame antenna having a capacitor in the frame. The path of the circuit 56 provides an inductor through hole 57 and ground. The other ground leg in the connector 78 is placed in the through hole 58, which is not connected to the antenna circuit. The antenna circuit provides a frame antenna with a capacitance and an inductance in parallel with the circuit tuned to an impedance of fifty ohms. The antenna printed circuit board 50 is supported by a support structure 60, which is best seen in Figure 3, and has a Y-shaped base 61, three legs 62 emerging from the ends of the base 61, and legs 63 at the ends of the legs 62 that are received in the holes 51 in the printed circuit board 50. The antenna support 60 also has a projection 64 (Figure 2) that extends downward from its central portion to place the support structure 60 in a depression 39 (Figure 2) in the cover 42 of the inner metal housing 40. In the present embodiment, the antenna printed circuit board 50 is placed slightly above the cover of the metal pit 15 when the transponder assembly 10 is attached to the lid of the pit 15. However, in embodiments for use in concrete or plastic pit housings, the transponder assembly 10 may be mounted by a mounting flange having a threaded opening similar r to the lid 22, but fastened by screws below the lid of the pit 15. In these alternative embodiments, the antenna can be placed below the pit lid. The present invention could also be used in other transponder and remote transmitter assemblies, provided that the energy requirements for the transponder are reduced in accordance with FCC regulations. As shown in Figure 2, a rigid coaxial cable 70 is supported in a vertical position by a support structure 43. As shown in more detail in Figure 4, the cable 70 has a top end electrically connected to the antenna printed circuit board 50 and a lower end connected to the transponder printed circuit board 90. At the upper end, a ground connector 78 connects the outer shield of the coaxial cable to two silver through-holes 58, 59 in the antenna printed circuit board 50. The signal conductor 77 in the coaxial cable 70 connects a third silver-plated through hole 57 in the antenna printed circuit board 50. At the lower end, a second ground connector 79 connects the outer shield of the coaxial cable 70 to two silver through holes 91 on the transponder printed circuit board 90 (only one hole is shown in Figure 4). The signal conductor 77 in the coaxial cable 70 connects to a third through hole 92 in the printed circuit board of the transponder 90. Where the coaxial cable 70 passes through an extruded hole in the upper part of the cover 42 ( Figure 4) of the inner housing 40, the hole is sealed with welding material 71. This provides a solid ground connection for the coaxial shielding through the metal housing 40. Also as shown in Figures 4 and 7, the cable coaxial 70 also passes through an opening in the eccentric center of the Y-shaped member 48. With reference again to Figures 2 and 8, a lower compartment in the assembly houses a battery 65. The lower compartment is formed by a base member 86 (Figure 8) and a battery case member 69 (Figure 8). The base member 86 supports the inner housing 40. With reference to Figure 8, the base member 86 has a cylindrical shape with a closed upper end and an open lower end. The base member 86 forms an encapsulation well 87 and the wire entry port 89 where the cable 21 enters the assembly, is connected to the printed circuit board of the transponder 90 and where the connection is sealed with encapsulation material 88 as shown in Figure 2. As shown further in Figure 8, a first cylindrical post 84 having a threaded hole 106 for receiving a fastener is formed integrally with the encapsulation well 87. Opposed to the first post 84 is a second hollow, semi-cylindrical post 85 that forms a second injection port for encapsulation material 88. The two separate posts 84, 85 are also used to position the battery case 69 when assembled to the base member 86. The battery case 69 is formed to hold a single battery 65 in this mode. The battery 65 is connected by tips 66 to the connector 68 via a battery circuit board 67. This set of parts 65-68 is placed in the battery case 69, with the circuit board supported by the poles 72 having legs 73 to hold and locate the circuit board 67. The battery 65 is received in the semi-cylindrical battery passage 74 in which the separators 75 are formed to support the battery 65 above the wall of the box. A first guide channel member 76 is formed in a wall of the battery case that extends around the circuit board 67. A network 80, partially visible in Figure 8, runs perpendicular to the through hole 74 along the the bottom of the box to a well 81. The network 80 provides a place to grip the battery case 69 with a thumb and an annular finger when the battery assembly 65-69 is installed or removed in the larger assembly 10. The well 81 is necessary to form another channel guide member 82. The members 76, 82 provide semicircular canals 83 for sliding in the posts 84, 85 formed in the base member 86 so as to locate the battery case 69. applies a vaseline to the receptacle 68 to prevent the encapsulation material 108 from flowing into the openings to receive the legs 94. When the battery subassembly is assembled, the battery 65 is placed in the box 69 and a sealing material 108 is placed inside, around and on the battery 65 as shown in Figure 2. This sealing material 108 is softer, more ductile and has a time of cured longer than the sealing material 88. The base member 86 has an elastic seal 93 formed by a protective ramp that tracks a profile of the open side of the battery case 69, but is sized to fit within the walls outer of the battery case 69, when pressed against the base member 86. The elastic joint 93 is separated a short distance within the walls of the case 69. The sealing material 108 is filled in, around and over the battery 65 in the subset of the components 69, 86 and allowed to cure and solidify. However, it remains deformable, and when the battery case 69 and the battery are installed in the elastic joint 93, the elastic joint 93 is pressed into the soft body of sealed material 108 and inserted therein. As shown in Figure 8, the elastic joint 93 also orientates the battery case 63 so that the 2-leg receptacle 68 on the dashboard of the battery 67 will be aligned with two legs 94 on an electrical connector 95 to make connection to the printed circuit board of the transponder 90. The legs 94 on the electrical connector 95 extend through a plastic body 109 to support and mount the connector 95. The legs 94 are received in a receptacle 96 mounted on the board printed circuit 90. The cable 21 with the plug receptacle 98 is inserted and connected as shown in Figure 2. The cable 21 has three insulated wires 111, one of which is shown in Figure 2. The three insulated wires are inserted into a cable insulation jacket 112. A metal reinforcement relief collar 113 is folded into the cable insulation jacket 112, and prevents a length of cable 21 from being pulled through the cable entry port. wire 89. A vulcanizing sealant / adhesive at room temperature 88 is admitted through port 85 until it fills the annular space (Figures 2 and 7) between the side wall 27 of the housing 24 and the side wall of the inner housing 40. The housing 24 has a tapering shoulder 97 at the upper end of the side wall 27 to prevent the sealant from entering the antenna chamber 35. Tapering the shoulder 97 causes the side wall 27 of the outer housing 24 to tightly against the side wall of the inner housing 40. This sealed coupling prevents the sealing material 88 from entering the area where the lid 41 is attached to the body of the metal housing 42. This isolates the sealing region for the cover 41 from the body of the sealing material 88, when separating the two seals and interrupting the communication of substantial fluid between the annular space between the side walls of the housing and the sealing region of the cover 41. The cable receptacle 98 is connected to the legs 99 of the connector 100 (Figures 2 and 3A) to electrically connect the cable 21 to the connector 100. The electrical connectors 95, 100 are pre-assembled with the inner housing 40. using molded discs of epoxy adhesive 101. The epoxy adhesive is used to cover the grooves 102 in the metal housing body 41 to secure the plastic bodies 109, 110 of the connectors 95, 100 in place and isolate the legs 94, 99 of the body of the metal housing 41. The three legs 99 of the connector 100 are aligned along an axis that is rotated 90 ° of an alignment axis for the two legs 94 of the connector 95. Similarly, the receptacle 96 in FIG. the printed circuit board 90 is rotated 90 ° from an alignment axis for the receptacle 104 on the printed circuit board 90, as shown in Figure 3A. Additionally, the distance of a first space between the first and second legs 99 is 0.254 cm, while the distance of a second space between the second and third legs 99 is 0.508 cm. The space between the legs 94 is 0.254 cm. The asymmetric configuration of the legs 94, 99 ensures proper orientation and electrical connection of the battery case assembly to the printed circuit board 90 in the inner housing 40. Instead of using the receptacles 96, 104, the legs 94 and 99 also they could be soldered directly to the printed circuit board 90. After the battery case 69 with the battery 65 is assembled in the case 86, the cable 21 has been connected and the sealing operations, the lower cover 23, have been completed. (Figure 2) is attached and fastened with a screw 25 (Figure 2) that is received in a threaded hole 106 in the post 84 (Figure 8). The screw 25 has a head that requires a specific screwdriver to insert and remove the screw 25, which provides resistance to violations of the box. Although the preferred embodiment uses a battery case with a battery, a battery case for two batteries and for larger single batteries is also contemplated within the scope of the invention. In a set of this type, the box can be oriented perpendicular to the position of the battery 65 with respect to the posts 84, 85, and the battery case can more fully fill the cavity in the base member 86. This has been a description of examples of the manner in which the invention can be carried out. Those skilled in the art will recognize that various details may be modified to arrive at other detailed embodiments, and these embodiments will be within the scope of the invention. Therefore, to inform the public of the scope of the invention and the embodiments covered by the invention, the following claims are made.