GB2325306A - Gas meter housing - Google Patents

Abstract

A gas meter is provided with an outer housing of parallelepiped form which comprises two parts 54,76 which mate along a plane which intersects the diagonal of each of the two side faces 82a of the housing. The inlet and outlet ducts 64, 66 (figure 9) of the meter pass through apertures in the top face of the housing. The housing parts may be press formed form steel sheet or may be of plastic and may have flanged mating edges 54e, 76a. An electronic module 81 can be fitted to one of the end faces 82d or 82c and because there is no horizontal flange around the housing this can be done using a single seal 83, thus simplifying the construction.

Description

A GAS METER HOUSING The invention relates to a gas meter having a housing of a substantially parallelepiped form having three opposing pairs of faces, the housing comprising two cover parts joined together at their periphery.

Conventionally, a gas meter has a housing of a substantially parallelepiped form having three opposing pairs of faces. The housing comprises two cover parts joined together at their periphery by a flanged peripheral edge provided on each cover part, as described in U.S. patent 4 593 562.

The type of domestic gas meter 10 described in this document is shown in Figure 1.

Each cover part 12, 14 has substantially the shape of a cup having an end 12a, 14a and a peripheral wall 12b, 14b that are perpendicular to one another.

The projecting peripheral edge 12c, 14c provided on each part 12, 14 respectively lies on a plane that is parallel to the end face 12a, 14a of the cover part.

An inlet duct 13 (Fig.l) and an outlet duct 15 (only represented in Fig.3b) are both provided on one end 12a of the cover parts 12, 14.

During the manufacturing process, each cover part is formed e.g. by press forming of a sheet of metal (e.g. steel, aluminium...).

For this operation, (Fig.2), the sheet of metal 16 rests on the peripheral part 1 8a of a fixed support 18 above a cavity 20 which has substantially the shape of a cup with the opening facing upwards.

A tool 22 moveable along the vertical direction is disposed above the sheet of metal 16 and has a projection 22a which matches the shape of the cavity 20.

The tool 22 is vertically lowered towards the sheet of metal and pressed against it to cause its deformation inside of the cavity so as to exactly fit into the cavity 20.

However, during the press forming operation each of the parameters of the process (pressure applied to the tool, speed of lowering of the tool, lubrication...) has to be controlled carefully in order to avoid rupture of the metal sheet against the 90" angle between the vertical peripheral face 1 8b and the horizontal peripheral edge 1 8a of the cavity 20 as well as between the vertical peripheral face 1 8b and the horizontal face 1 8c constituting the bottom of the cavity.

This type of gas meter 10 is often equipped with a module 24 (Fig.3a) affixed to one 26 of the faces of the housing and which comprises electronic circuitry (printed circuit boards...) associated with the measurement unit of the meter, a display unit to visualize the gas consumption and a battery unit.

Given that electronic circuitry is sensitive to humidity and dust coming from ambient atmosphere, an air tight sealing has to be achieved between the module 24 and the front face 26 of the housing in order to protect electronics.

As there are two horizontal flanged peripheral edges 12c, 1 4c on the housing, two sealing rings 28, 30 have to be provided both above and below the edges as shown in Figs3a and 3b.

Such a sealing makes the manufacturing of the module and the fixation of the sealing rings 28, 30 in the module 24 difficult.

To overcome at least one of the above-mentioned drawbacks, the invention providesa gas meter having a housing of a substantially parallelepiped form having three opposing pairs of faces, the housing comprising two cover parts joined together at their periphery, the plane of the join between the two cover parts lying substantially on a plane that intersects the diagonal of each of two opposing faces of the parallelepiped, an inlet and an outlet duct being both provided on one of the faces of the housing which is adjacent to the opposing faces of the parallelepiped, thereby giving a U shape to the gas flow.

Thus, when the housing is made of metal the invention avoids the metal of the sheet being torn during the press forming operation since the angles between the plane of the join and the faces of the housing that are adjacent to the opposing faces are much less than 90" and then the metal undergoes a smaller deformation than in the past.

As a consequence, the parameters of the process can be much less carefully controlled than in the past.

Due to the position of the plane of the join between the cover parts according to the invention only one sealing ring is required to provide the air tight seal between the electronic module and the housing.

Preferably, each cover part is provided with a flanged peripheral edge.

Preferably, each cover part has substantially the shape of a hollow triangular right prism.

According to a preferred embodiment, a gas measurement unit is associated with one of the cover parts in a tight sealing manner.

In addition, the measurement unit is equipped with fixation means.

Fixation means connect the measurement unit with the first two opposing faces of the parallelepiped respectively.

Fixation means are constituted by pins and recesses such that pins are mounted on the measurement unit and engage into recesses provided in the first two opposing faces respectively.

The invention will now be described, by way of example only, with reference to the accompanying drawings in which: - Fig 1 is a schematic view of a prior art gas meter, - Fig 2 shows the press forming operation of a cover part of a prior art gas meter, - Fig 3a is a schematic view of a prior art gas meter equipped with an electronic module (only the module is shown in cross-section), - Fig 3b is a perspective view of the prior art gas meter represented in Fig3a with the sealing rings 28, 30 only, - Fig 4 shows the press forming operation of a cover part of a gas meter according to a preferred embodiment of the invention, - Fig 5 is a schematic cross-sectional view of the cover part obtained by the press forming operation shown in Fig 4, - Fig 6 is a perspective view of the inside of the cover part shown in Fig 5, - Fig 6a is an enlarged view of a part of the cover part represented in Fig 6, - Fig 7 is a perspective view of the outside of the cover part shown in Fig 6 and equipped with two ducts, - Fig 8 is a schematic view representing the assembly phase of the measurement unit in a cover part and the joining of the two cover parts respectively, - Fig 9 is a front view of the inside of the cover part shown in Fig 8 and which is equipped with the measurement unit, - Fig 10 represents a possible method of fixation of the two cover parts, - Fig 11 a is a side view of an assembled housing according to an embodiment of the invention, - Fig 1 1b illustrates another possible embodiment of an assembled housing, - Figs 12a and 12b respectively show two side views of a gas meter housing according to the invention and to the prior art, respectively, - Fig 13 shows a schematic view of a gas meter housing made of plastic and assembled according to the invention.

As shown in a cross sectional view in Fig 4, a steel sheet 32 having, for example, a thickness of 0.8mm and a rectangular shape of 200mm x 142mm rests on a fixed lower tool 34 through its periphery 32a.

A cavity 36 is provided in the lower tool in the middle of the horizontal part 34a of the tool which is in contact with the metallic sheet.

In this cross-sectional view the cavity is substantially V-shaped with the walls of said cavity being inclined relative to the horizontal direction with an angle far inferior to 900, e.g. 30 for the wall 34b and 60 for the wall 34c.

In another cross-section which is shown in the direction indicated by the arrow noted A in Fig4, the cavity 36 is substantially U-shaped.

An upper tool 38 disposed above the metallic sheet 32 is moveable in the vertical direction and is guided in its movement by two guiding members 40, 42 which extend across the upper and lower tools into respective aligned holes 44, 46, 48, 50.

The upper tool 38 projects towards the sheet and the projection 38a matches the shape of the cavity 36 so as to perfectly fit into this cavity. The shape of this cavity defines the shape of the cover part which will be formed.

When the press forming procedure is started the upper tool 38 is lowered at a predetermined speed into the metallic sheet under a predetermined pressure supplied by the press 52 which is partially represented in Fig 4.

Thus, the sheet 32 is progressively deformed within the cavity until it comes in contact with the walls 34b, 34c thereof.

The resulting press formed shape of the steel sheet is shown in cross section in Fig 5 and in perspective in Fig 6 and constitutes a cover part 54.

As represented in these drawings, the cover part 54 has four adjacent faces 54a, b, c, d, including two rectangular large faces 54a, b arranged at an angle of 90" with respect to each other and two triangular small opposing faces 54c, d, and a flanged peripheral edge 54e in contact with each of these faces.

Thus, the cover part 54 has substantially the shape of a hollow triangular right prism (Fig6).

During the press forming operation, in the plane of Fig4, the steel sheet is bent over an angle which is less inferior to 90" for the two adjacent faces 54a and 54b and which corresponds to the above-cited values of30" and 60 respectively (Fig4).

Although, the steel sheet is bent over an angle of 90" with regard to the peripheral edge 54e so as to form the opposing faces 54c and 54d, in the other cross section which is viewed in the direction indicated by the arrow A, the overall deformation of the metal sheet is much less damaging than in the prior art gas meters where the metal sheet had to be deformed over an angle of 90" between the flanged peripheral edge and all the peripheral faces and between the latter and the bottom face.

Consequently, such a deformation is very much less likely to give rise to a tearing of the steel sheet than is the case in the prior art, such that the control of the process parameters can be simplified.

Setting of the parameters of the press forming tools is therefore easier.

During the press forming operation two apertures 56, 58 are simultaneously provided in the same large face 54a of the cover part 54.

Also two identical triangular recesses 60, 62 are respectively provided in the small opposing faces 54c, 54d of the cover part and partly in the peripheral edge 54e at the same height.

Fig 6a is an enlarged view of the recess 60 provided in the face 54c.

The recesses 60, 62 may be substantially aligned on a line which lies in a plane of symmetry P of the two apertures 56, 58, passing by these apertures (Fig6).

Over the next step of the process, two ducts 64, 66 are conventionally crimped on the perforated large face 54a of the cover part around the two apertures 56, 58 respectively (Fig7).

The fact that the two ducts are mounted on the same face of one cover part allows the position of the centres of the ducts and therefore the distance between these centers to be accurately controlled.

The next step of the process is schematically represented in Fig 8.

A measurement unit 68, parallelepiped in shape for example, has a right angle exit 70 in the form of a chimney. This unit is vertically lifted along the vertical arrows shown in Fig 8 inside the cover part 54 towards the large face 54a of the cover part which is provided with the ducts 64, 66 so as to firmly engage the chimney-shaped exit 70 in the aperture 58 and the duct 64 in a tight sealing manner.

The measurement unit 68 is also equiped with two pins 72, 74 respectively mounted on two opposing side faces 68a, 68b of said unit.

These pins 72, 74 are lying in a vertical plane (Figs 8 and 9) which corresponds to the above-cited plane of symmetry P of both apertures 56, 58 and ducts 64, 66.

When the measurement unit 68 is connected with the aperture 58 and duct 64 the two pins 72, 74 are accommodated in the respective recesses 60, 62. This helps to mechanically support the measurement unit and then to avoid that the connexion between the chimney-shaped exit 70 and the cover part 54 be submitted to too high stresses.

It will be appreciated that the measurement unit is a block which is not necessarily parallelepiped in shape.

A second cover part 76 is built in the same way as described with reference to Fig 4, except that no recesses and no apertures are provided therein and that the measurement unit is only installed with regard to the first cover part 54. Thus, the manufacturing process is simplified.

When the two cover parts 54, 76 are joined together in the direction of the horizontal arrows shown in Fig 8, the peripheral edge 76a of the second cover part 76 makes contact with the peripheral edge 54e of the first cover part 54 and the pins 72, 74 of the measurement unit 68 are thus prevented from disengaging the recesses 60, 62.

Consequently, the measurement unit 68 is firmly secured and supported between the two cover parts 54, 76.

This is made more effective if the pins 72, 74 are substantially lying on a vertical plane which intersects the center of gravity of the measurement unit. Normally, once the cover parts are firmly secured to one another they have not to be separated from each other.

By way of example, the measurement unit comprises a longitudinal duct in which the gas flows and two ultrasound transducers respectively facing the opposite ends of said duct. The flow of gas enters the measurement unit 68 via an aperture 75 located opposite the chimney 70 and exits through this chimney. Other types of measurement units could also be used, as for instance, fluidic oscillators, volumetric measurement units as in US patent 4 593 562...

The two respective peripheral edges 54e, 76a of the cover parts 54, 76 are fixed together, e.g. by welding.

However, this fixation can also be achieved as shown in Fig 10.

In this embodiment, one 78 of the cover parts 78, 80 has a projecting peripheral edge 78a which is longer than the other and may be folded back on the other edge 80a, as represented by the arrows in dotted lines, and the overlapping structure is then compressed so as to ensure the closure and the sealing of the housing.

By having the two ducts 64, 66 mounted on the same face of one cover part it ensues that any forces induced on the meter by the ducts upon installation of said meter will not apply on the join between the cover parts.

Fig 1 la represents a gas meter housing according to the invention as described above and in which the plane of the join between the two cover parts lies substantially on a plane that intersects the diagonal of each of two opposing faces 82a, b of the parallelepiped.

In this figure only one face 82a is shown directly.

When an electronic module 81 is affixed onto one of the faces of the housing this can be done either on face 82c or 82d and given that there is no horizontal flanged peripheral edge projecting from the considered face as in the prior art gas meter (Figs3a and 3b) only one sealing ring 83 (Figl la) can be used instead of two.

Moreover, the mechanical structure of the module 81 can be significantly simplified with regard to that of the prior art (Fig 3) as well as the mounting operation of the sealing ring 83.

As represented in Fig 1 lb, the cover part 81a of the electronic module can also be placed in front of one 82c of the faces of the housing 82 and affixed onto the peripheral edge 76a so as to completely mask the cover part 76.

Figs 1 2a and 1 2b also illustrate another advantage of the invention.

If each of the different housings 82, 10 represented in Figs 12a, 12b has the same overall dimensions and volume it can be seen that the housing 82 in accordance with the invention (Figl2a) has a dimension L which is inferior to the dimension L' of the priort art housing 10 (Fig 12b) due to the fact that the projecting edges of the join are at an angle to the horizontal.

Thus, in some cases where there is no enough room to install a prior art gas meter, the meter according to the invention fits well with the available space.

It must be taken into account that the diagonal plane of the join between the cover parts could also be applied to a housing 84 made of plastic instead of metal (Figl3).

In such a case the cover parts 86, 88 do not need to have flanged peripheral edges as represented in Figs 5 to 12a since the two cover parts can be joined together through a small surface area, as shown in Fig 13.

The fixation between such plastic cover parts can be done e.g. by welding or snaping.

However, in such a case the diagonal plane ofjoin between the cover parts is still advantageous to avoid using two sealing rings and a complicated mechanical structure of an electronic module when the latter has to be affixed onto one of the faces of the housing.

As a matter of fact, if the plane ofjoin between the cover parts was lying on a plane that is perpendicular to said face of the housing (see Fig.3a) and if only one sealing ring was used, an air tight sealing between the module and said face of the housing could not be achieved because the sealing ring would cross the plane ofjoin that is not free of any defects on the surface and, at this location, the sealing ring would not perfectly apply against this plane ofjoin.

Claims (9)

1. A gas meter having a housing of a substantially parallelepiped form having three opposing pairs of faces, the housing comprising two cover parts joined together at their periphery, the plane of the join between the two cover parts lying substantially on a plane that intersects the diagonal of each of two opposing faces of the parallelepiped, an inlet and an outlet duct being both provided on one of the faces of the housing which is adjacent to the opposing faces of the parallelepiped.

2. A gas meter according to claim 1, wherein each cover part is provided with a flanged peripheral edge.

3. A gas meter according to any of the preceding claims, wherein each cover part has substantially the shape of a hollow triangular right prism.

4. A gas meter according to any of the preceding claims, wherein a gas measurement unit is associated with one of the cover parts in a tight sealing manner.

5. A gas meter according to claim 4, wherein the measurement unit is equipped with fixation means which prevent said measurement unit from being separated from said cover part.

6. A gas meter according to claim 5, wherein fixation means connect the measurement unit with the first two opposing faces of the parallelepiped respectively.

7. A gas meter according to claim 6, wherein pins are mounted on the measurement unit and engage into recesses provided in the first two opposing faces respectively.

8. A gas meter according to any of the preceding claims, wherein the housing is made of metal.

9. A gas meter according to any of the claims 1 to 7, wherein the housing is made of plastic.