MXPA97008285A - Accommodation of instrument with discharge space - Google Patents

Abstract

The present invention relates to an instrument housing having an upper part and a base assembled together, an assembly for electrostatic discharge comprising: a chassis within the instrument housing with a support for holding at least one pair of cables; a pair of cables having isolated portions and having uncovered portions where the pair of cables is mounted to the support, wherein the base is formed of a conductive material and wherein the base has at least one projection extending to one of the portions discovered, where the instrument contains a volume of a gas to conduct the electrostatic charge, so that a discharge space is provided between the projection and one of the uncovered portions of the cables through which the charge can be conducted the base of conductive material for unloading from inside the instrument

Description

ACCOMMODATION OF INSTRUMENT WITH SPACE OF ELECTRIC SHOCK Technical Field The invention relates to instruments for measuring quantities such as electricity, gas and water consumption.

Description of the Previous Technique In the field of water meters, a turbine or other flow measuring device is connected to the water supply line. The water consumption units are counted and displayed by a register unit which is mounted on the top of the flow measurement housing. The display can be a type of disk or a type of odometer or a combination of these. The register unit is operated by electromagnetic coupling, so that cables are not required to connect the flow measurement housing to the register unit. Inside the recorder is a pulse transmitter as described in Strobel et al., U.S. Patent No. 4,868,566, entitled "Flexible Piezoelectric Switch Activated Metering Pulse Generators". This pulse transmitter unit converts mechanical movements to electrical impulses. In certain units, the impulse must be transmitted by means of cables to certain remote responding units for transmission to a reading unit. The need for cable entry presents a problem, in which electrostatic charges can be experienced from events outside the measurement recorder or within the measurement recorder. There is an additional problem in assembling and manufacturing the recording unit by ejecting the air and introducing a gas such as helium to maintain the recorder's crystal area in a clear and readable state, similar to that of a pulse clock. The atmosphere filled with helium is somehow conductive of the electrical charge and, therefore, some means of electrostatic discharge is desirable. Certain methods using the Kapton tape and breastplates were not successful due to the conductivity of the helium gas inside the sealed register unit. The general objective of the present invention is to provide the electrostatic discharge for a sealed register unit particularly in a region where the cables enter the unit.

Brief Description of the Invention The invention relates to an instrument housing having wires entering the housing and a construction that provides electrostatic discharge.

The instrument contains a volume of a gas to conduct the electrostatic charge. The instrument has a pair of insulated cables that have portions where the insulation is partially removed and where the cables are mounted to a bracket on a chassis in the instrument housing. A housing base is formed of a conductive material and is formed with a projection extending upward toward the portions of the cables where the insulation has been removed, so that the space through which the load can be conducted is provided. towards the base of conductive material for discharge from inside the instrument The invention provides advantages in the cost of manufacturing the measurement recorder assembly The invention eliminates the need for a separate tape or protection The invention is applicable to many types of enclosures instrument, wherever the entry of a sealed cable is needed Other objects and advantages of the invention, in addition to those previously described, will be apparent to those skilled in the art from the description of the preferred embodiment which follows In the description, reference is made to the accompanying drawings, which are part of the same, and illustrate example However, such 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 Drawings Fig. 1 is a top plan view of the measurement recorder assembly embodying the present invention; Fig. 2 is a bottom plan view of the assembly of Fig. 1 with separate parts; Fig. 3 is an elevated sectional view of the assembly taken in the plane indicated by line 3--3 in Fig. 2; Fig. 4 is a detailed view of a portion of the assembly of Fig. 2; The Fig. 5 is a detail sectional view taken in the plane indicated by line 5--5 in FIG. 4; and Fig. 6 is a detail sectional view taken in the plane indicated by line 6-6 in Fig. 4.

Detailed Description of the Preferred Modality With reference to Figs. 1-3, the invention is incorporated into a measuring logger assembly 10 in which the insulated cables 21 enter through the base 12. The logger assembly 10 is shown without a plastic protective shield that is added to complete the logger unit. measurement. The assembly 10 includes a glass or glass dome 11. The base 12 is provided by a thin metal bronze plate formed and molded to add certain features. The glass 11 is attached to the base 12 by a sealing material 16, which can be one of many suitable epoxy adhesives known in the art. Observing through the glass 11 in FIG. 11, there is observed a disc indicator hand 13, a disk face 14 and an odometer assembly 15. As seen in FIG. 3, a disk face 14 is part of the plastic chassis that is supported by the chassis base 24 of plastic material that is formed in a complex configuration. further noted in FIG. 3, the recording unit 10 has a magnetic coupler 17 which is rotated by magnetic forces controlled from below by a water turbine unit (not shown). The magnetic coupler 17 is mechanically connected through a gear train (not shown) to drive the odometer 15 and the disk hand 14 to display the accumulated consumption. The magnetic coupler 17 is also mechanically connected to drive a cam 18 which is seen in Fig 2 When the cam 18 is advanced one position, a leaf spring 19 cantilevered at one end has a free end that moves laterally and then moves back towards its original position This movement or bending of the leaf spring 19 generates an impulse from the pulse transmitter unit 20 as explained in Stroebel et al, US Pat. No. 4,868,566, entitled "Flexible Piezoelectric Switch Activated Metepng Pulse Generators". The pulse transmitter unit 20 is connected by two wires 21 to another equipment for count and report accumulated impulses Cables 21 are marked for polarity Cables 21 are typically conductive 33 coated with PVC insulation material (PVC) 31 Conductors 33 are solid cable conductors A plug 22 (Fig 3), in the form of an insulating washer made of elastomeric material, projects through a opening 34 in a side wall 28 of the base 12 The insulating washer 22 has a flange and a slot portion 35 (Fig 2) for anchoring it in the side wall 28 and to prevent it from being pulled through the opening 34 The insulating washer 22 has three holes or passages 36 (Figs 2 and 3), two for cables 21 and a third passage 37 for receiving a copper relief tube 23 Cables 21 pass through the insulating washer and are then received in guides 27 (Fig 2) formed by parallel barriers 30 on the base 24 From there, the cables 21 move through the supports 25, 26 (Figs 2 and 3) on the base of chassis 24 and then make contact with the pulse transmitter 20 (Fig 2) The insulating washer 22, the cables 21 and the sealing material 16 are all installed in the assembly of the glass 11 to the base 12 During the assembly the relief 23 (Fig 2) prevents the air pressure from increasing within the unit 10 during assembly. After the air is dislodged through the of relief pipe 23, and the gas is introduced to dry the interior space 41 and prevent moisture from accumulating inside the recording unit 10. This gas can be helium or, a dry nitrogen could also be used to dry the interior space 41 in the recorder 10. The relief tube 23 is then closed by welding, the preferred form of closure, or by welding or bending the open end of the relief tube 23 The invention provides the stripped insulation 31 from the portions of the cables 21 in the region 42 (Figs. -6), where the cables are supported by the support 26, at a short distance from the copper base 12 The copper base 12 has one or more conical projections 43 that provide low inductance, high density, concentrated paths for the load electrostatics for discharge through the copper base 12, which is grounded. The interior space 41 is preferably filled with helium, which is sufficiently conductive to provide a discharge path from any part in the interior 41 to a space 44 (Fig 5) between the conical projections 43 and the stripped region 42 The space preferably has a linear dimension in the scale from 075 mm to 1 0 mm If a load develops electrostatic in the inner space 41, the invention provides the discharge through the space 44 towards the base 12, which is electrically connected to ground This has been a description of examples of how the invention can be carried out. Those skilled in the art will recognize that various details can be modified upon arriving at other detailed embodiments and, those 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 were made.

Claims (10)

1. In an instrument housing having an upper part and a base assembled together, an assembly for electrostatic discharge comprising: a chassis within the instrument housing with a support for holding at least one pair of wires; a pair of cables having isolated portions and having uncovered portions where the cable pair is mounted to the support; wherein the base is formed of a conductive material and wherein the base has at least one projection extending to one of the corresponding uncovered portions; wherein the instrument contains a volume of a gas to conduct the electrostatic charge; so that a discharge space is provided between the projection and one of the uncovered portions of the cable through which the charge can be conducted towards the base of conductive material for discharge from inside the instrument.

2. The assembly of claim 1, wherein the projection is conical in shape.

The assembly of claim 1, wherein the support is a support that depends on a portion of the chassis that is located on the base.

4. The assembly of claim 1, wherein the gas is helium.

5. The assembly of claim 1, wherein the cable pair includes solid conductors and wherein the insulated portions are insulated with a polyvinyl chloride material. The assembly of claim 1, wherein the instrument housing is for a service measurement device. The assembly of claim 1, wherein the assembly has a second support for holding the cable pair in addition to supporting the base portions of the cables near the electrostatic discharge space. The assembly of claim 1, wherein the space provides the separation between the projection and one of the uncovered portions of the cables on a scale from 0.75 mm to about 1.0 mm. The assembly of claim 1, wherein the base has at least one projection and another projection, each projection being conical and each projection extending toward one of the respective uncovered portions of the cables. 10. A sealed instrument comprising: a housing having an upper part and a base; a chassis inside the instrument with a support to hold at least a pair of cables; a pair of cables having isolated portions and having uncovered portions where the cable pair is mounted to the support; wherein the base is formed of a conductive material and wherein the base has at least one projection extending upward towards the uncovered portions, wherein the instrument contains a volume of a gas to conduct the electrostatic charge, so that an electrostatic discharge space is provided between the projection and one of the uncovered portions of the cables through which the charge can be conducted to the base of conductive material for discharge from inside the instrument 11 The sealed instrument of claim 10 , wherein the projection is conical 12 The sealed instrument of claim 10, wherein the support is a support that depends on a portion of the chassis that is located on the base 13 The sealed instrument of claim 10, wherein where the gas is helium 14 The sealed instrument of claim 10, wherein the pair of cables includes solid conductors and in where the isolated portions are insulated with a polyvinyl chloride material or the sealed instrument of claim 10 wherein the instrument housing is for a service measuring device 16 The sealed instrument of claim 10, wherein the assembly it has a second support to hold the pair of wires in addition to the support that holds the uncovered portions of the cables near the electrostatic discharge space. 17. The sealed instrument of claim 10, wherein the space provides the separation between the projection and one of the uncovered portions of the cables on a scale from about 0.75 mm to about 1.0 mm. 18. The sealed instrument of claim 10, wherein the base has at least one projection and another projection, each projection being conical and each projection extending toward one of the respective uncovered portions of the cables.