Abstract:
A fluid flow system, casing and method according to which a chamber is formed in the casing and at least one conduit is coupled to the casing so that fluid passes from the conduit and into the chamber and so that forces acting on the conduit creates stresses on the casing that causes flexure of the casing. At least one groove is formed in the wall of the casing defining the chamber, and is configured and located relative to the chamber to direct the flexure away from the wall of the casing defining the chamber.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application is based on provisional application Ser. No. 60/073,586 filed on Feb. 3, 1998. 
    
    
     BACKGROUND 
     This invention relates to a fluid flow system, casing, and method and, more particularly, to such a system, casing and method designed to be used with a meter for metering flow of the fluid. 
     Casings are often provided in a fluid flow line for housing a component, such as a flow meter. In these arrangements, the casing is usually placed in the fluid flow path and is provided with a chamber in which the meter, or other component, is installed. Conduits are also connected to the casing by mounting plates and bolts to pass the fluid through the casing. However, the casing is subjected to stresses caused by various bending moments on the conduits, the plates and the bolts. These stresses distort the physical shape of the chamber which often interfere with the operation of the meter, or other component. 
     Although there have been attempts to combat these stresses by adding material to the outside of the casing in an attempt to strengthen it, this adds to the cost, size and weight of the casing and therefore is undesirable. Therefore, what is need is a casing for housing a component in a fluid flow path that is not affected by the above stresses yet is not relatively high in cost, size and weight. 
     SUMMARY OF THE INVENTION 
     Accordingly an embodiment of the present invention is directed to a fluid flow system, casing and method according to which a chamber is formed in the casing and at least one conduit is coupled to the casing so that fluid passes from the conduit and into the chamber and so that forces acting on the conduit creates stresses on the casing that causes flexure of the casing. At least one groove is formed in the wall of the casing defining the chamber, and is configured and located relative to the chamber to direct the flexure away from the wall of the casing defining the chamber. 
     As a result, the casing not affected by the above stresses yet is relatively inexpensive and is not bulky or heavy. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a isometric view of a casing according to an embodiment of the present invention shown in connection with a fluid flow meter. 
     FIG. 2 is an enlarged view of the casing of FIG.  1 . 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring to FIG. 1 of the drawings, the reference numeral  10  refers to a meter for metering the flow of fluid, such as gas, through a fluid flow system. The meter  10  can be of any conventional type such as a positive displacement, rotary type meter, and includes a cover, or housing  12 , having an annular flange  12   a  extending outwardly therefrom that has a plurality of angularly-spaced openings for receiving bolts  14  for reasons to be explained. An accessory unit, in the form of an instrument  16 , extends outwardly from the housing  12  and is adapted to provide a visual indication of the amount of fluid that is metered, in a conventional manner. Although not shown in the drawings, it is understood that the meter  10  includes a impeller, or the like that disposed inside the cover  12  that rotates in response to the presence of a pressurized fluid, as will be described. 
     With reference to FIGS. 1 and 2, a casing  20  is provided which is approximately rectangular in cross section and which has an internal measurement chamber  22  (FIG. 2) for receiving the meter  10 . As shown in FIG. 1, the meter  10  extends through the chamber  22  with the cover  12  and the instrument  16  protruding outwardly from the casing. Although not shown in the drawings, it is understood the above-mentioned impeller of the meter  10  is centered in the chamber and that another cover protrudes out from the opposite end of the casing  20 . 
     The casing  20  is provided with an outlet port  24  (FIG. 2) that receives an outlet conduit  26  that, in turn, is connected to the casing by an annular mounting plate  28  that receives the conduit. An inlet port (not shown) is provided on the other side of the casing that receives an inlet conduit  32  that, in turn, is connected to the casing by an annular mounting plate  34  that is connected to the latter side wall by another series of bolts (not shown). The axes of the conduits  26  and  32  thus extend perpendicular to the axis of the chamber  22 . 
     The inlet port and the outlet port  24  both extend into the chamber  22  so that the fluid flows from the inlet conduit  32 , through the chamber  22 , and to the outlet conduit. During the passage of the fluid through the chamber  22 , it passes through the above-mentioned impeller of the meter  10  which meters the amount of fluid flow which registers on the instrument  16 . With the exception of the specific design of the casing  20  that will be described in detail, all of the above is conventional and therefore will not be described in any further detail. 
     As discussed above, forces acting on the conduits  26  and  32  and the meter  10  establish moment arms that apply stresses to the casing  20  through the plates  28  and  34 , the bolts  30 , and the bolts associated with the plate  34 . These stresses will cause the structure of the casing  20  to flex and thus distort the precise configuration of the chamber  22 . This can cause the impeller of the meter  10  to malfunction due to the flexed wall of the casing  20  defining the chamber  22  actually engaging and interfering with the meter&#39;s impeller. 
     According to a feature of an embodiment of the present invention, the chamber  22  of the casing  20  is configured in a unique manner to isolate the meter from the above stresses. To this end, the cross-sectional shape of the chamber  22  shown is FIG. 2 is generally in the form of an ellipse  22   a  having a horizontal axis that is slightly less in length than the vertical axis, as viewed in FIG.  2 . Two notches  40  and  42  are formed in the wall of the casing defining the chamber  22  and extend for the entire length of the chamber. The notches  40  and  42  are located on the opposite sides, or the relatively long walls, of the chamber as viewed in the drawing. A pair of elongated grooves  40   a  and  40   b  are cut into the casing  20  and extend from the opposite ends of the notch  40 , and a pair of elongated grooves  42   a  and  42   b  are also cut in the casing  20  extend from the opposite ends of the notch  42 . The grooves  40   a ,  40   b ,  42   a , and  42   b  extend for the entire length of the chamber  22  and generally parallel to portions of the inner wall of the casing  20  defining the corresponding portions of the chamber. The notches  40  and  42  and the grooves  40   a ,  40   b ,  42   a , and  42   b  are sized to not reduce the load bearing properties of the casing  20 . 
     Thus, any stresses occurring on the portions of the casing  20  adjacent the the plates  28  and  34  caused by forces acting on the conduits  26  and  32 , respectively, as discussed above will cause the latter portions to flex. However, the grooves  40   a ,  40   b ,  42   a , and  42   b  are constructed and arranged to direct this flexure away from the wall of the casing  20  defining the chamber  22  and thus isolate, or decouple, the chamber from the structure of the casing that receives the plates  28  and  34 . Thus, the physical shape of the chamber  22  is not changed, yet the casing  20  does not require additional material that adds to the cost, size and weight of the casing. 
     It is understood that variations can be made in the foregoing without departing from the scope of the invention. For example, the shape of the chamber and the grooves can vary within the scope of the invention as long as the above results are achieved. Also, the number of conduits connected to the casing and the number of notches and grooves formed in the casing can vary. Further, the spatial references referred to above, such as “upper”, “lower”, “side”, etc., are for illustration purposes only and are not intended to limit the specific location or orientation of any of the structure. Still further, the casing of the above embodiment is not limited to use with a meter but can be used in connection with other components. 
     Other modifications, changes and substitutions are intended in the foregoing disclosure and in some instances some features of the disclosure will be employed without a corresponding use of other features. Accordingly, it is appropriate that the appended claims be construed broadly and in a manner consistent with the scope of the invention.