WO2000012969A2

WO2000012969A2 - Gas meter diaphragm

Info

Publication number: WO2000012969A2
Application number: PCT/US1999/020008
Authority: WO
Inventors: Mark J. Regan; Ralph L. Gooch
Original assignee: Flexfab Horizons International, Inc.
Priority date: 1998-09-01
Filing date: 1999-09-01
Publication date: 2000-03-09
Also published as: WO2000012969A9; WO2000012969B1; WO2000012969A3; AU5798899A

Abstract

A gas meter diaphragm is formed from liquid injected silicone rubber, with an integral annular bead (124) that permits its attachment to a pan assembly (80) without retaining rings or adhesives. By using liquid injected silicone rubber, the diaphragm can be molded rather than cut from a material sheet, allowing the diaphragm to have integrally formed retaining rings (124, 120, 220) or other physical features (100) or other physical features (100) with varying thicknesses of material.

Description

GAS METER DIAPHRAGM BACKGROUND OF THE INVENTION

Field of the Invention

This invention relates to a gas meter and, more particularly, to an improved diaphragm for a gas meter.

Prior Art

In a diaphragm-type gas meter, a quantity of gas is delivered to an appliance, such as a furnace, stove or the like, by way of measuring chambers that include reciprocating diaphragms driven by gas pressure. Generally, the gas is introduced into a gas meter housing through an inlet port formed in the gas meter housing and then alternately introduced into measuring chambers formed in the housing through a distributing valve mechanism. In a four-chamber gas meter, there are two pairs of measuring chambers, each pair having a diaphragm that separates the measuring chambers. A control rod connecting each diaphragm to a crank post controls the motion of that diaphragm. The control rod and the crank post, acting together, control the length of the stroke of each diaphragm and coordinate the timing of the stroke of each diaphragm to the stroke of the other diaphragm in the meter. In some meters, temperature variations are compensated for by employing a bi-metallic device on the crank post that varies the length of the stroke of the diaphragms in direct proportion to the absolute temperature of the gas being metered.

Each diaphragm has a corresponding valve controlling the flow of pressurized gas to each. The valve opening is timed to begin to admit gas to the chamber on one side of the diaphragm when the diaphragm's position is approaching its minimum volume. Gas exiting the diaphragm flows through an outlet port to supply gas to the appliance, furnace, etc. The timing of the valves is coordinated to the volume of the chambers by a mechanism that connects each valve to the crank post. Typically, an adjustment feature on the crank post allows small, precise changes to the valve timing for final meter calibration. This adjustment allows for the advancement or retardation of the valve's movements. Gas volume is measured by counting the revolutions of the crank post. This is accomplished by a geared connection between the crank post and a mechanical counter.

A conventional diaphragm assembly includes a rigid diaphragm pan having an open face that is closed by a flexible diaphragm, which has a generally circular shape adapted to fit over the open face. The peripheral edges of the diaphragm are secured to a portion of the housing defining the open face by seating a retaining ring in a groove formed about the periphery of the housing defining the open face. The retaining ring is preferably made of coiled metal, or some other material strong enough to retain the edge of the diaphragm in the groove once the retaining ring is seated. A relatively hard center portion, preferably formed from tin metal, is attached to the center of the diaphragm. Preferably, the hard center portion is formed from a pair of thin metal plates joined to one another on opposite sides of the diaphragm with the center of the diaphragm secured therebetween. The outer plate of this assembly mounts a bracket for attaching control rods connecting the diaphragms to the crank post and the valve drive mechanism. When the diaphragms are oscillated, the valve drive mechanism is adjusted by rotation of the crank post, which also turns the counter via a meter gear, thereby rotating index dials based upon the amount of gas flowing through the meter.

Heretofore, fabricating a diaphragm assembly for a gas meter was labor intensive. The diaphragm must be cut from a roll or sheet of uncured, fabric-coated rubber or other similar flexible material to a size adapted to fit over the open face of the diaphragm housing. It is then formed over a mandrel and heated for sometimes hours until it is shaped or cured. Then, the inner and outer plates are fastened to one another with the diaphragm therebetween, which requires time for properly aligning and fastening. Also, the periphery of the diaphragm must be secured to the diaphragm housing. It is generally preferred that some sort of adhesive be applied to the groove, and then a retaining ring be seated against the diaphragm to retain it within the groove. Excess material of the diaphragm must be trimmed around the edges of the diaphragm housing. The outer peripheral edge of the diaphragm is held between the groove and the retaining ring, and sealed by the tension of the retaining ring and bonding of the adhesive. In addition to the complicated and time-consuming fabrication, the prior diaphragm assembly is also known to have an additional disadvantage in that the diaphragm can "snap-through" as the center portion or plate is reciprocated to expand and contract the chamber defined by the diaphragm. The "snap-through" effect occurs when a portion of the diaphragm extending from the central portion to the rigid diaphragm pan inverts or changes its curvature toward the diaphragm pan during the inward stroke of the center portion. The inverted portion of the diaphragm can interfere with the reciprocation of the diaphragm by inhibiting the free relative movement of the center portion or changing the path of the plate with respect to the rigid diaphragm pan. A snapped-through diaphragm can also reduce the volume of the diaphragm chamber, producing inaccurate metering.

SUMMARY OF THE INVENTION

The invention relates to a diaphragm for a gas meter diaphragm assembly. The gas meter diaphragm assembly comprises a pan and a plate connected by a diaphragm. The pan and plate each have a peripheral groove. The diaphragm comprises a rim and a rib connected by a sidewall. The rim defines a first opening and is configured to be received within the pan peripheral groove. The rib is spaced from the rim and defines a second opening. The rib is configured to be received within the plate peripheral groove. The rim, rib, and sidewall provide the diaphragm with a toroidal configuration with the first and second openings forming a pass-through opening. The sidewall, rib, and rim are preferably integrally formed as one piece from a gas impermeable elastic material, such as liquid silicone rubber.

The diaphragm can further include a flange extending from the sidewall and spaced from the rim so that the flange is adapted to abut a portion of the pan when the rim is received within the pan peripheral groove. The rim can further comprise a bead that is sized to be received within the pan peripheral groove. The combination of the flange and the bead enhance the seal between the plate and the diaphragm.

The rib can be formed with multiple protrusions that are sized to be press-fit within the plate peripheral groove. For example, the multiple protrusions can comprise at least two opposing and laterally extending ribs, alone or in combination with two spaced legs. The rim and rib are preferably continuous and disposed annularly about the diaphragm.

The sidewall can comprise at least one substantially straight portion and at least one arcuate portion. A strengthening rib can be positioned adjacent the junction of the sidewall straight portion and arcuate portion. Preferably, the strengthening rib is continuous and extends circumferentially about the diaphragm.

In another aspect, the invention relates to a gas meter comprising a housing defining at least one outer metered chamber and a corresponding gas inlet. The gas meter further includes a diaphragm assembly comprising a pan and a central plate, which are connected by a flexible diaphragm. The diaphragm assembly defines an inner metered chamber and is positioned within the at least one outer metered chamber. A valve assembly is provided for controlling the flow of gas through the inner and outer metered chambers by reciprocating the central plate of the diaphragm assembly relative to the pan. The improvement in the gas meter comprises making the diaphragm from liquid silicone rubber.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of a gas meter housing illustrating the environment of the invention;

FIG. 1A is a partial cross sectional view taken along line lA-lA of FIG. 1 ; FIG. 2 is an exploded view of the gas meter housing of FIG. 1 , and showing a diaphragm assembly according to the invention;

FIG. 3 is a partial side elevation view of a crank post assembly shown in FIG. 2;

FIG. 4 is a top plan view of the crank post assembly of FIGS. 2 and 3; FIG. 4A is a top plan view of the plate to which the diaphragm assembly of

FIG. 2 to mounted;

FIG. 5 is a perspective view of the diaphragm assembly of FIG. 2 with a diaphragm in a compressed state;

FIG. 6 is a perspective view of the diaphragm assembly of FIG. 2 with a diaphragm in an expanded state;

FIG. 7 is an exploded view of the diaphragm assembly of FIG. 2; FIG. 8 is a top plan view of the diaphragm in the diaphragm assembly of FIG. 7;

FIG. 9 is a side sectional view taken along line 9-9 in FIG. 8;

FIG. 10 is an enlarged partial sectional view of the area marked X in FIG. 9; FIG. 11 is an enlarged partial sectional view of the diaphragm assembly illustrating the relationship of the components marked XI in FIG. 7;

FIG. 12 is a partial sectional view of the diaphragm assembly illustrating the relationship of the components marked XLI in FIG. 7;

FIG. 13 is an exploded view of a diaphragm assembly similar to FIG. 7, but illustrating an alternative form of the diaphragm and central plate,

FIG. 14 is a top plan view of the diaphragm in the diaphragm assembly of FIG. 13;

FIG. 15 is a side sectional view taken along line 15-15 in FIG. 14;

FIG. 16 is an enlarged partial sectional view of the area marked XVI in FIG. 15;

FIG. 17 is an enlarged partial sectional view of the diaphragm assembly illustrating the relationship of the components marked XVLI in FIG. 13;

FIG. 18 is a partial sectional view of the diaphragm assembly illustrating the relationship of the components marked XVILI in FIG. 13; FIG. 19 is an exploded view of a diaphragm assembly similar to FIGS. 7 and

13, but illustrating an alternative form of the diaphragm and central plate;

FIG. 20 is a top plan view of the diaphragm in the diaphragm assembly of FIG. 19;

FIG. 21 is a side sectional view taken along line 21-21 in FIG. 20; FIG. 22 is an enlarged partial sectional view of the area marked XXII in

FIG. 20;

FIG. 23 is an enlarged partial sectional view of the diaphragm assembly illustrating the relationship of the components marked XXHI in FIG. 19;

FIG. 24 is a partial sectional view of the diaphragm assembly illustrating the relationship of the components marked XXrV in FIG. 19; and

FIG. 25 is an enlarged perspective view of the central plate shown in FIG. 19. DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1 shows a typical multi-chamber gas meter of the type made and sold by Equimeter, Inc. of DuBois, Pennsylvania. The gas meter 10 comprises a housing 16 including an inlet port 12 and an outlet port 14. As shown in Figures 2, 3, and 4, a valve drive mechanism 18, mounted within the housing 16, is actuated by diaphragm assemblies 32, 34 through control rods 26, 28. The rods 26,28 are operationally linked through an adjustment mechanism 20 to a crank post 22, which turns an intermediary shaft 23, which rotates a gear 24. The gear 24 is linked to a meter index (not shown) in a counter mechanism 25, in which dials are rotated to show the quantity of gas passing through the meter 10.

The valve drive mechanism 18 is connected through first and second diaphragm control rods 26, 28, via depending lower arm portions 30, which in turn are connected to diaphragm assemblies 32, 34, each including a flexible diaphragm 82. As gas flows through the meter, the diaphragms 82 are oscillated, which urge the control rods 26, 28 to rotate the crank post 22.

As shown in Figure 2, an upper portion of the meter 10 is separated from a lower portion by a plate 78, which supports the valve drive mechanism 18 and seals the two portions except for the selective openings formed by a pair of valve members 56, 58 Further, the lower portion of the gas meter housing 16 is divided into a first chamber 36 and a second chamber 38 divided by a partition 40, and each chamber 36, 38 is selectively supplied with gas by the valve members 56, 58, respectively. The first diaphragm assembly 32 is disposed within the first chamber 36 and the second diaphragm assembly 34 is disposed within the second chamber 38. In this manner, the lower portion of the housing 16 is divided into multiple metering chambers, each chamber 36, 38 being divided into two metering chambers: a first outer meter chamber 33 formed within the chamber 36 but outside the diaphragm assembly 32, a first inner meter chamber 35 formed within the diaphragm assembly 32, a second outer meter chamber 37 formed within the chamber 38 but outside the diaphragm assembly 34, and a second inner meter chamber 39 formed within the diaphragm assembly 34. FIG. 4A illustrates the ports to the respective chambers through the plate 78. A first outer meter chamber port 74 communicates with the first outer meter chamber 33. A first inner meter chamber port 75 communicates with the first inner meter chamber 35. A second outer meter chamber port 76 communicates with the second outer meter chamber 37, and a second inner meter chamber port 77 communicates with the second inner meter chamber 39. A channel 79 is positioned to direct gas from any of the ports 74, 75, 76, 77 to the outlet port depending upon the position of the valve members 56,58.

In operation of the multi-chamber gas meter 10, a relatively uniform driving torque from the diaphragm assemblies 32, 34 to the crank post 22 is provided by the two diaphragm assemblies 32, 34 oscillating essentially 180° out of phase in response to gas selectively supplied to each assembly 32, 34 by its respective valve members 56, 58. As illustrated best in figures 3 and 4, alternate expansion and contraction (as shown in FIGS. 5 and 6) of the two diaphragm assemblies 32, 34 urges the crank post 22 to rotate by way of the valve drive mechanism 18 and, more specifically, by means of a common crank pin 50 rotationally mounted offset from the crank post 22. First and second links 42, 44 connect the control rods 26, 28 via first and second flag arms 46, 48 to the crank pin 50. Each stroke of each diaphragm assembly 32, 34 i.e., action from a compressed position as shown in FIG. 5 to an expanded position as shown in FIG. 6 or vice versa, generates 180° rotation of the crank post 22. The two diaphragm assemblies 32, 34 operate in tandem with one expanding, as the other is simultaneously compressed. Also, the timing of each valve member 56, 58 is coordinated to the diaphragm strokes.

As shown thus in FIG. 4, the first diaphragm flag arm 46 is connected at one end to the first diaphragm control rod 26 and, at an opposite end, pivotally connected to one end of the link 42. Similarly, the second diaphragm flag arm 48 connects at one end to the second diaphragm control rod 28, which, in turn, is connected through its depending lower arm portion 30 to the second diaphragm assembly 34, and pivotally connected at an opposite end to one end of the second link 44. The other ends of the first and second links 42, 44 are both pivotally connected to the crank pin 50. The crank pin 50 is eccentrically disposed relative to the crank post 22 and is connected to the adjustment mechanism 20 therebetween. The crank post 22 is rotationally mounted to a support housing 54 attached to the plate 78 and is also connected to the adjustment mechanism 20. The crank post 22 further comprises a worm 72 that drives the intermediary shaft 23, which, in turn, drives the meter index gear 24 when rotated. Rotation of the crank post 22 also drives the valve members 56, 58 to control the flow of gas to and from the meter chambers 33, 35, 37, 39. The valve members 56, 58 are laid out in a 90° spaced apart relationship on the support housing 54 to selectively open or close the ports 74, 75, 76, 77 and are actuated by the crank post 22 via a crank throw 60. The crank throw 60 is disposed intermediately on the crank post 22, as best shown in figures 3 and 4. To accomplish the desired valve strokes, two separate arms 62, one on each side of the crank post 22 for each valve member 56, 58, are connected to the crank post 22 via the crank throw 60, about which they are coaxially mounted for pivotal movement relative thereto. The opposite end of the arm 62 is pivotally connected to its respective valve member 56, 58. Further, each valve member 56, 58 includes a guide arm 64 that slidably mounted to a support 66 at a first end and fixedly attached to one side of the valve member 56, 58 on an opposite end. Similarly, the opposite side of each valve member 56, 58 includes a second guide arm 68 slidably mounted in a support 66 on a first end and fixedly mounted to the side of the valve member 56, 58 at the other end. The guide arm 64 and support 66 assembly guides the sliding motion of each valve member 56, 58.

Each valve member 56, 58 includes a cover with curved and flat portions which effectively act as a gate with respect to ports 74, 75 and 76, 77 respectively. In the intermediate position of either valve member 56, 58, all ports are simultaneously closed. At either end of the strokes, a port is open to either the respective inner or outer meter chamber. In a distal end position, as shown for valve member 58 in FIG. 4, the second inner meter chamber port 77 is open, establishing fluid communication between the inlet port 12 and the second inner meter chamber 39. At the same time, the second outer meter chamber port 76 establishes communication between the second outer meter chamber 37, the channel 79, the outlet port 14. In a proximal end position, as shown for valve member 56 in figure 4, the first inner meter chamber port 75 is open so that the first inner meter chamber communicates with the channel 79, and the outlet port 14. Simultaneously, the first outer meter chamber port 74 establishes communication between the first outer meter chamber 33 and the inlet port 12.

Gas is typically pressurized to ^XΛ lb. gauge (about 7 inches of water) at the inlet 12. As shown best in FIG. 4 and 1A, 5 and 6, when either valve member 56, 58 is in a distal end position, the gas enters the diaphragm assembly 32 by traveling a flow path designated by arrow "A." When either valve member 56, 58 is in the proximate end position as shown for valve member 56 in FIG. 4, pressurized gas in the upper portion of the housing follows the flow path designated "C." Thus, at the position illustrated in FIGS. 1 A and 4, gas is being directed via path A into the second inner meter chamber 39 and simultaneously via path C into the first outer meter chamber 33. Introduction of gas into the second inner meter chamber 39 causes the diaphragm assembly 34 to expand, displacing the gas in the second outer meter chamber 37. The displaced gas is consequently directed along path "B" through the second outer meter chamber port 76 and the channel 79 to the outlet port 14. At the same time, introduction of gas into the first outer meter chamber 33 compresses the diaphragm assembly 32, especially to gas along path B through the first meter chamber port 75 and the channel 79 to the outlet port 14.

While this is occurring, the displacement of the diaphragms in the diaphragm assemblies 32, 34 moves the control rods 26, 28, which in turn uses the flag arms 46, 48 and links 42 to move the crank pin 50. Any motion of the crank pin 50 necessarily imparts rotation to the crank post 22 which simultaneously moves the valve members 56, 58 and the shaft 23 and counter mechanism 25.

The simultaneous oscillation of the diaphragm assemblies 32, 34, 180 degrees out-of-phase with one another, corresponds perfectly to a 360-degree rotation of the crank post 22. In this manner, the oscillations of the diaphragm assemblies 32, 34 drive the control rods 26, 28 and thus the valve drive mechanism 18 via the crank post 22 to actuate the valve members 56, 58. The crank post 22 consequently also rotates the intermediary shaft 23, which drives the meter gear 24 for the counter 25. As best shown in figures 5-7, the diaphragm assemblies 32, 34 each generally comprise a diaphragm pan 80, preferably made of plastic, and having an open face covered by a flexible diaphragm 82, preferably formed of silicone rubber. The diaphragm pan 80 is a generally circular shell including an outwardly flared sidewall 84 extending from the periphery of a circular bottom wall 86. The sidewall 84 includes a fluid port 88 and a mounting arm 90, which is adapted to abut a mounting block (not shown) formed in a bottom surface of the housing 16 defining each of the first and second meter chambers 36, 38. Further, near the fluid port 88 is a pair of mounting apertures 94 for securing the assembled diaphragm assembly 32, 34 to the plate 78 mounting the valve drive mechanism 18. The rim of the sidewall 84 includes a pair of laterally spaced annular ribs 96 defining an arcuate or v-shaped groove 98. As shown in FIGS. 7-10, the flexible diaphragm 82 comprises an annular rim

122 connected to an annular rib 120 by a sidewall 102, which includes a generally straight portion 102a and a generally arcuate portion 102b. The annular rim 122 defines a relatively wide opening 103 and the annular rib 120 defines a more narrow opening 101. The openings 101 and 103 provide a pass-through opening for the entire diaphragm. A radially inwardly extending annular flange 100 is provided on the interior surface of the sidewall 102 just below the annular rim 122. A bead 126 extends radially inwardly from the inner surface of the annular rim 122. The flange 100 and bead 126 abut the sides of the pan rib 96 to form seals between the diaphragm and the pan on both sides of the rib 96. Preferably, the flexible diaphragm 82 is made from liquid silicone rubber.

The large opening 101 is covered by a center plate assembly or inner disc assembly 104, which includes mounting brackets 106 for the diaphragm control rods 26, 28, respectively. The inner disc assembly 104 comprises an inner plate 108 and outer plate 110 having approximately the same diameter. Each plate 108, 110 has a rolled peripheral edge 112, 114, respectively. The rolled edges 112, 114 are disposed outwardly such that when the inner and outer plates 108, 110 are joined to one another back-to-back, the rolled edges 112, 114 extend in opposite directions about the periphery of the inner disc assembly 104, thereby forming the annular groove 116. When the plates 108, 110 are thus secured to one another, the groove 116 is adapted to receive the annular rib 120. It will be understood that the inner disc assembly 104 can comprise a single integrated disc, formed of metal or plastic, with an annular groove -l i¬

on its periphery. The inner disc assembly need have only sufficient rigidity to maintain its shape and support the mounting brackets 106 and drive the control rods 26, 28.

To assemble the diaphragm assembly, the inner plate 108 is received within the opening 103 of diaphragm 82 and positioned against the annular rib 120. The outer plate 110 is positioned at the diaphragm opening 102 on the opposite side of the plate 108 to form the groove 116, within which the annular rib 120 is received. The plates 108 and 1 10 are the secured to each other. The plates 108, 110 can be secured to one another using any well-known means, such as welding, or conventional fasteners 1 19, such as rivets, secured through apertures 118 formed in the inner and outer plates 108, 110.

Alternatively, the plates 108, 110 can be secured together without the prior positioning of the annular rib 120 between the plates 108, 110. For this alternative, the rib 120 can be stretched over the groove 116 of the combined plates to secure the diaphragm 82 to the disc assembly 104. Once the center plate assembly 104 is secured in the opening 101 of the diaphragm 82, the assembly is secured to the pan 80.

As shown in FIG. 12, the bead 126 is seated in the groove 98 formed between the ribs 96 in the pan 80. The bead 126 is simply inserted in the groove 98 as the diaphragm 82 is stretched about the periphery of the pan 80 until the entire bead 126 is seated in the groove 98. Because of the nature of the silicone rubber from which the diaphragm 82 is made, a sealing ring or other retaining ring is not necessary to ensure that the bead 124 remains seated in the groove 98 during normal use. Alternatively or additionally, an adhesive may be applied to the groove 98 before the bead 124 is seated, whereby a fluid-tight seal can be more assured. Under normal operating conditions, however, an adhesive is not necessary.

The diaphragm assembly according to the invention, and especially the diaphragm 82, addresses many shortcomings of the prior art diaphragm assemblies and diaphragms. Since the diaphragm 82 has a toroidal shape with both an inlet opening and an outlet opening wherein the edge of the diaphragm 82 forming the outlet opening is received within a channel in the center plate assembly 104, it is not necessary to form the complex rounded dome-like diaphragm of the prior art, which required a great deal of manufacturing resources, especially manual fabrication. The diaphragm 82, according to the invention, can easily be molded, which greatly reduces the fabrication time and cost.

The diaphragm 82 is preferably molded using a liquid silicone rubber (LSR) compound which is superior to the conventional reinforced calendared nitrile material was heretofore used because LSR diaphragms can be molded with integral seals. LSR is stable over time, remains flexible over a wide temperature span, and is relatively easy to mold. Preferably, the diaphragm is molded by a liquid injection process. LSR will remain virtually unchanged and unaffected by natural gas for at least 20 years. FIGS. 13-18 show an alternative embodiment of the diaphragm according to the invention. In this embodiment, like components bear like numerals for ease of reference. It can be seen that the principal difference with the alternative embodiment is a second annular rib 220 on the radially inwardly extending flange 100. The ribs 120 and 220 are laterally displaced from and parallel to one another with dimensions similar to corresponding grooves 216 on the center disc assembly 204. In FIGS. 16 and 17, it can be seen that a portion 228 of the inner plate 108, adjacent the rolled edge 112 is offset laterally from a central portion of the outer plate 1 10. This offset portion extends in a plane parallel to the center portion and is offset in a direction opposite the outer plate 110. A portion adjacent the rolled edge 114 of the outer plate 110 includes a pair of grooves 216 laterally displaced from the periphery of the inner plate 108. When the plates 108, 110 are secured to one another, the offset portion 228 and the grooves 216 are adapted to receive the pair of annular ribs 120, 220.

The liquid silicone rubber diaphragm 82 includes integrally formed annular ribs and beads on the outer and inner diameters respectively. The outer seal bead 126 snaps into the groove 98 in the pan 80 and the inner seal ribs 120 are received in grooves 116 and clamped between the plates 108, 110. The clamping force is supplied by a number of fasteners 119, preferably rivets, and probably 6 or 8 in number, disposed adjacent the inner seal ribs 120. The use of LSR for the diaphragm 82 will greatly simplify assembly as the outer seal bead 124 does not require reinforcement to ensure the integrity of this seal, but is simply formed by seating the sealed bead 124 in the groove 98. Further, the LSR diaphragm can be molded, thus material is conserved over one prior art which required cutting and forming calendared nitrile material to fit.

FIGS. 19-26 illustrate a third alternative embodiment of the diaphragm assembly according to the invention. In this embodiment, like components bear like numerals for ease of reference. It can be seen that the principle differences between the third embodiment and the first and second embodiments is that the center plate assembly 304 is formed as a single piece and the diaphragm 82 includes multiple circumferential ribs 306, 308. The single-piece plate 304 comprises a generally planar surface 310 in which is formed a pair of mounting openings 312 adapted to receive fasteners 314 for fastening the mounting bracket 106. A peripheral groove 316 is formed along the peripheral edge of the planar surface 310, preferably by deforming a portion of the plate 304 by conventional means, such as spinning.

The diaphragm 82 is similar to the prior diaphragms in that it comprises an annular rim 322 and an annular rib 320 that are connected by a sidewall 302. The sidewall 302 comprises three straight portions 302a, 302b, and 302c, which are connected by curved portions 302d and 302e.

As within the previous embodiments, an annular flange 300 extends from the sidewall 302 and is spaced slightly below a bead 326 formed on the annular rim 322. The circumferential strengthening ribs 306, 308 are positioned on the straight portions 302a and 302c just prior to and just after the corresponding arcuate portions 302d and 302e, respectively. In these positions, the circumferential ribs 306 and 308 are most effective in resisting the "snap-through" of the sidewall 302, especially the straight portion 302b, during the reciprocation of the diaphragm 82. It should be noted that the location and size of the strengthening rib will vary depending on the shape of the diaphragm, the particular gas meter, and the desired operational characteristics of the diaphragm.

An additional difference of the third embodiment is that the annular rib 320 does not have a circular cross section as shown in the prior embodiments. The annular rib 320 includes laterally extending side lobes 320a, 320b and outwardly extending bottom lobes 320c and 320d. The lobes 320a-d are, in essence, circumferential beads extending from what would otherwise be a circular cross section. The circumferential lobes and shoulders 320a-d are sized and located so that the lobes 320a and 320b abut the portion of the plate 304 forming the sidewalls of the channel 316 and the legs 320c and 320d abut the bottom wall forming the channel 316, effectively providing a four point seal for the annular rib 320 with respect to the channel 316.

The third embodiment disclosed in FIGS. 19-26 has the additional advantages of the plate 304 being made from a single piece, which even more greatly simplifies and reduces the fabrication costs and time of the diaphragm assembly. Additionally, the annular rib 320 provides an improved seal between the diaphragm 82 and the center plate 304. Further, the strengthening ribs 306, 308 provide additional structural support for the diaphragm, which effectively eliminates any "snap-through" of the diaphragm that could potentially interfere with the reciprocation of the diaphragm assembly.

While the invention has been specifically described in connection with certain specific embodiments thereof, it is to be understood that this is by way of illustration and not of limitation, and the scope of the appended claims should be construed as broadly as the prior art will permit. For example, the rim, bead, flanges, ribs, strengthening ribs, etc., are all shown as being continuous and circumferential or annular. It is within the scope of the invention for these elements to be non- continuous and/or non-circumferential. The thickness of the these elements can also vary depending on the operational characteristics and environment of the diaphragm.

Claims

CLAIMSWHAT IS CLAIMED IS:

1. A diaphragm (82) for a gas meter having a diaphragm assembly comprising a pan with a peripheral groove and a plate with a peripheral groove, opposing the pan, the diaphragm comprising: a rim (122) defining a first opening and configured to be received within a pan peripheral groove; a rib (120), spaced from the rim, defining a second opening and configured to be received within a plate peripheral groove; and a sidewall (102) extending between the rim and the rib wherein the sidewall (102), the rib (120), and the rim (122) are integrally formed as one piece from an elastic material.

2. The diaphragm according to claim 1 wherein the elastic material is gas- impermeable.

3. The diaphragm according to claim 1 or 2 wherein the elastic material is silicone rubber.

4. The diaphragm according to claim 1, 2, or 3 and further comprising a flange (100) extending from the sidewall and spaced from the rim so that the flange is adapted to abut a portion of a pan when the rim is received within a pan peripheral groove.

5. The diaphragm according to claim 1 or 4 wherein the rim further comprises a bead (126) that is sized to be received within a pan peripheral groove.

6. The diaphragm according to claim 1 or 4 wherein the rib has multiple protrusions that are sized to be press fit within a plate peripheral groove.

7. The diaphragm according to claim 6 wherein the multiple protrusions comprise at least two opposing, laterally extending ribs.

8. The diaphragm according to claim 7 wherein the multiple protrusions comprise at least two spaced legs.

9. The diaphragm according to claim 1 or 4 wherein there are two ribs (120, 220).

10. The diaphragm according to claim 9 wherein the two ribs are concentrically spaced from one another.

11. The diaphragm according to claim 1 or 4 wherein the rim and the rib are continuous.

12. The diaphragm according to claim 11 wherein the rim and rib are annular.

13. The diaphragm according to claim 12 wherein the sidewall comprises at least one substantially straight portion and at least one arcuate portion.

14. The diaphragm according to claim 13 and further comprising a strengthening rib positioned adjacent the junction of the sidewall straight portion and arcuate portion.

15. The diaphragm according to claim 14 wherein the strengthening rib is continuous.

16. The diaphragm according to claim 14 wherein the strengthening rib is circumferential.

17. The diaphragm according to claim 1 and further comprising a strengthening rib extending from the sidewall.

18. The diaphragm according to claim 17 wherein the strengthening rib is continuous.

19. The diaphragm according to claim 18 wherein the strengthening rib is circumferential .

20. In a gas meter (10) comprising a housing (16) defining at least one outer metered chamber (33) and a corresponding gas inlet (12), a diaphragm assembly (32) comprising a pan (80) and a central plate (78) connected by a flexible diaphragm (82) and defining an inner metered chamber (35) and being positioned within the at least one outer metered chamber, and a valve assembly (18) for controlling the flow of gas through the inner and outer metered chambers by reciprocating the central plate relative to the pan, the improvement wherein: the diaphragm is made from silicone rubber.

21 . The gas meter according to claim 20 wherein the diaphragm comprises: a rim (122) defining a first opening and configured to be received within the pan peripheral groove; a rib (120), spaced from the rim, defining a second opening and configured to be received within the plate peripheral groove; and a sidewall (102) extending between the rim and the rib and providing the diaphragm with a toroidal configuration with the first and second forming a pass through opening.

22. The gas meter according to claim 21 wherein the sidewall (102), the rib (120), and the annular rim (122) are integrally formed as one piece from a gas- impermeable elastic material.

23. The gas meter according to claim 21 and further comprising a flange (100) extending from the sidewall and spaced from the rim so that the flange is adapted to abut a portion of the pan when the rim is received within the pan peripheral groove.

24. The gas meter according to claim 21 wherein the rim further comprises a bead (126) that is sized to be received within the pan peripheral groove.

25. The gas meter according to claim 24 wherein the rib has multiple protrusions that are sized to be press fit within the plate peripheral groove.

26. The gas meter according to claim 20 wherein there are two ribs (120, 220).

27. The gas meter according to claim 26 wherein the two ribs are concentrically spaced from one another.

28. The gas meter according to claim 27 wherein the rim and the rib are continuous.

29. The gas meter according to claim 28 wherein the rim and rib are annular.

30. The gas meter according to claim 20 wherein the sidewall comprises at least one substantially straight portion and at least one arcuate portion.

31. The gas meter according to claim 30 and further comprising a strengthening rib positioned adjacent the junction of the sidewall straight portion and arcuate portion.

32. The gas meter according to claim 31 wherein the strengthening rib is continuous.

33. The gas meter according to claim 32 wherein the strengthening rib is circumferential.

32. The diaphragm according to claim 20 wherein the plate is one piece.