Abstract:
A fluid meter ( 10 ) has a casing ( 11 ) providing a measuring chamber ( 27 ) and an inlet ( 18 ) and outlet ( 19 ) communicating with the measuring chamber ( 27 ). A partition ( 20 ) in the chamber ( 27 ) separating said inlet ( 18 ) from said outlet ( 19 ). A disc ( 28, 48 ) is positioned in the chamber ( 27 ) and includes projections ( 36 ) or niches ( 57 ) which are disposed in an arc relative to a center of the disc ( 28, 48 ) and the casing is provided with integrally formed depressions ( 37 ) or with projections ( 56 ) disposed opposite the projections ( 36 ) or niches ( 57 ) on the disc ( 28 ) to be engaged the disc ( 28 ) as the disc ( 28, 48 ) is nutated with the result of counteracting forces imposed on said disc ( 28, 48 ) by fluid flow.

Description:
TECHNICAL FIELD 
   This invention relates to fluid meters and in particular to improvements in meters utilizing a nutating disc for measuring the flow of fluid through the metering chamber. 
   DESCRIPTION OF THE BACKGROUND ART 
   Certain well known fluid meters, including water meters, utilize a nutating disc metering element to measure the flow of fluid through a metering chamber. The fluid passing through the metering chamber imparts a nutating (wobbly) motion to the disc which is converted to a rotary motion or other motion to actuate a counter or register for the meter. The pressure and velocity of fluid entering the metering chamber provides considerable force on the nutating disc, and this force is transmitted to the measuring chamber housing where contact between the two elements occurs. The forces imparted by the fluid must be counteracted to insure the accuracy and the proper functioning of the meter. 
   For many years, a thrust roller mechanism has been used to counter such forces. This mechanism is disclosed in Miller, U.S. Pat. No. 1,957,661, which was assigned to the assignee of this invention, and a good depiction is illustrated in Thomson, U.S. Pat. No. 10,022, FIG. 17. A thrust roller is attached to the disc diametrically opposite the inlet of the measuring chamber, where the thrust roller rolls up and down in a slot in the meter casing. Such slots utilize various types of bearing inserts which are placed in proximity to the roller to minimize wear and reduce friction, which would impede proper nutation of the disc. These inserts are replaceable and are of common use in nutating disc type metering devices which are used by many municipalities for metering water used by subscribers. Such thrust rollers and inserts tend to wear over time and present certain problems in manufacture, assembly and servicing of the meter. 
   SUMMARY OF THE INVENTION 
   The invention provides a nutating disc meter with a construction that will resist forces imparted on the disc by the fluid without using the conventional thrust bearing found in many nutating disc meters. 
   The invention provides a bearing for a nutating disc which provides reliable performance, is simple to replace, and which eliminates the moving parts required with conventional thrust rollers currently used in nutating disc chambers. 
   The invention is provided in a metering assembly having a nutating disc disposed in a chamber. The disc is formed with either projections or depressions that engage the complementary one of these which are formed on the casing as the disc is nutated. The depressions and projections can be integrally formed on the disc and chamber parts to eliminate moving parts provided by the thrust roller bearing of the prior art. 
   The projections engage the depressions as the disc is nutated to counteract rotational forces imposed on said disc by fluid flow. 
   The invention eliminates the conventional thrust roller which cooperates with a vertically extending slot in the disc chamber. The invention also counteracts the forces normally absorbed by the thrust roller and helps absorb the force against the disc as the disc straddles the usual partition associated with a metering chamber. 
   The invention also provides additional detailed teachings in the manner of shaping and locating the projections and depressions. 
   The invention provides a disc meter that has a lower cost of manufacture than prior art constructions. 
   Other objects and advantages of the invention, besides those discussed above, will be apparent to those of ordinary skill in the art from the description of the preferred embodiments which follows. In the description, reference is made to the accompanying drawings, which form a part hereof, and which illustrate examples of the invention. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a perspective view of a metering assembly that incorporates the present invention; 
       FIG. 2  is a top plan view of the assembly of  FIG. 1 ; 
       FIG. 3  is an exploded perspective view of the assembly of  FIG. 1 ; 
       FIG. 4  is a top plan view of a bottom casing part of the assembly of  FIGS. 1 and 2 ; 
       FIG. 5  is a top plan view of a nutating disc in the assembly of  FIGS. 1–3 ; 
       FIG. 6  is an enlarged sectional view taken in the plane indicated by line  6 — 6  in  FIG. 2 ; 
       FIG. 7  is a sectional view taken in the plane indicated by line  7 — 7  in  FIG. 2 ; 
       FIG. 8  is a detail section view taken in the plane indicated by line  8 — 8  in  FIG. 7 ; 
       FIGS. 9–11  are views of a second embodiment, which correspond to the views in  FIGS. 4 ,  5  and  6 , respectively. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   Referring to  FIG. 1 , a fluid metering assembly  10  has a generally cylindrical casing  11  with an upper casing part  12  and a lower casing part  13 . The upper casing part forms a hub  14  and seen on top of the hub  14  is a rotatable, magnetic element  15 , which may have 2*n magnetic poles, where n is a variable integer such as “1” or “2.” This magnetic element  15  rotates at least a part of one revolution up to one revolution for each unit of consumption. A magnetic pickup (not shown) is used to detect these rotations which counted by a meter counter or register (not shown) of a type well known in the art. 
   The casing parts  12 ,  13  have molded projections  16 ,  17  for situating the casing  11  inside of an external metal meter housing (not shown) of a type well known in the art. The housing could also be made of plastic. This external meter housing would also include threaded spouts for attaching the assembly a fluid supply line. 
   As seen in  FIGS. 1 and 2 , the fluid metering assembly  10  has an inlet  18 , an outlet  19  and a partition  20  for separating the two parts of the flow stream in an interior of the casing  12 . The outlet  19  would typically have a seal (not shown) disposed on an outlet port formed  19   a  to isolate the outlet flow from the inlet  18 . The inlet  18  would typically have a screen (not shown) across its opening to prevent foreign particles from entering a chamber  27  ( FIG. 6 ) in the casing  12 . 
   Referring to  FIG. 3 , further details of these parts are illustrated. It can be seen that the magnetic element  15  is annular in shape with a central web that forms a hole for receiving an upper end and head of a shaft of a crossbar unit  22 . It can also be seen that the partition  20  is formed by a half section  20   a  on the upper casing part  12  and by a half section  20   b  on the lower casing part  13 . The outlet  19  is completely formed in the side walls of the casing parts  12 ,  13 , while the inlet  18  is formed in both the side walls  23 ,  24  and the upper and lower concave walls  25 ,  26 . 
   The casing parts  12 ,  13  form a chamber  27  ( FIG. 6 ) in which a disc element  28  is assembled. As seen in  FIGS. 3 ,  4  and  5 , the disc  28  has a radial slot  29  that receives the partition  20  within the chamber  27 . The disc  28  has a spherical hub portion  30  also seen in  FIG. 6 , which slides and rotates in concave bearings  31 ,  32  formed in the upper and lower casing parts  12 ,  13 . 
   Referring to  FIG. 6 , the lower casing part  13  forms a control cone  33  on an interior bottom of the housing  11  with an annular groove  34  around the control cone  33 , and a spherical portion  30  of the disc  28  has an integrally formed spindle  35  that extends from the spherical portion  30  to a lower end of the spindle  35  contacting the control cone  33  and traveling around in the groove  34  around the control cone  33 , and to an upper end traveling in a circle to rotate a crossbar unit  22 . The inverted T-shaped crossbar unit  22  (seen best in  FIG. 3 ) couples rotations of the upper end of the spindle  35  to rotations of the magnet assembly  15 . 
   As further seen in  FIG. 6 , the upper and lower walls  25 ,  26  of the casing parts  12 ,  13  are disposed at an angle in the range from about 170 to about 230 to allow the disc member  15  to move up and down through a tilt angle of corresponding range as the tilted spindle  35  of the disc  28  travels in a circle around the control cone  33 . 
   Referring again to  FIG. 3 , as incoming fluid is admitted through inlet  18 , it enters the metering chamber  21  underneath the disc  28  and tends to lift the disc  28 . This lifting action travels around in a circle and when it reaches the other side of the chamber  27  from the inlet  18 , the portion of the disc  28  near the inlet  18  will tilt downward. This produces the well known nutating movement or wobble action as fluid passes through the chamber  27 . 
   The disc  28  has raised, elongated ridges  36 , while the casing  12 ,  13  form grooves  37  for receiving the ridges  36  on the nutating disc  28 . As seen in  FIGS. 7 and 8 , the grooves  37  have tapering side walls from a wider opening to a narrower bottom, and the ridges  36  have tapered sides from a wider base to a narrower projecting extremity which facilitate the engagement of the ridges  36  in the grooves  37 . As seen in  FIG. 3 , the disc  28  with its spherical portion  30 , spindle  35  and ridges  36  is molded in one piece of a suitable resinous material. Similarly the casing parts  12 ,  13  are also molded parts, thus reducing the part count over prior constructions. 
   The geometrical layout of the ridges  36  and grooves  37  is seen in  FIGS. 3 ,  4  and  5  where a first set of raised, elongated ridges  36  are formed on an upper surface of the disc. There are also a second set of raised, elongated ridges  36  formed on a lower surface of disc  28  at a corresponding positions to the first set. These ridges  36  are disposed on radii from a center of the disc  28 , however, they could also be curved and disposed as spaced arcing ridges. A first set of elongated grooves  37  are formed on an interior surface of an upper casing wall  25  ( FIG. 7 ) to receive the ridges  36  on the upper surface of the disc  28  and a second set of elongated grooves are formed on an interior surface of a lower casing wall  26  to receive the ridges  36  on the lower surface of the disc  28 . On the lower casing part  13 , these grooves  37  are also formed along radii from a center of the control cone  33  which corresponds to a geometrical center of the disc  28 . On the upper casing part  12 , they are formed along radii from a center of the axis of rotation of the magnetic element  15 , which is aligned to the center of the disc  28  and the center of the control cone  33 . 
   As the disc  28  moves in its wobbly motion in  FIG. 7 , first one projection  36  is engaged in a corresponding groove  37  and the succeeding projections  36  are engaged in corresponding grooves  37  around the interior of the metering chamber  27  from the inlet  18  to the outlet  19 . With this traction, the disc  28  is capable of absorbing and counteracting the incoming pressure of the fluid which imposes lines on the spherical portion  30  and tends to rotate the spherical portion  30  and disc  28 . The disc  28  absorbs these forces in a unique manner since it is actuated by the incoming fluid and eliminates the necessity for the utilization of the thrust roller bearing and slot arrangement normally found on the side of the measuring chamber which is directly opposite the partition  20 . 
   As seen in  FIGS. 7 and 8 , the grooves  37  have tapering side walls from a wider opening to a narrower bottom, and the ridges  36  have tapered sides from a wider base to a narrower projecting extremity which facilitate the engagement of the ridges  36  in said grooves  37 , with less friction, thereby reducing wear. 
     FIGS. 9 ,  10  and  11  illustrate a second embodiment in which the parts are similar to the parts in  FIGS. 1–8 , with the following exceptions. The casing parts  12   a ,  13   a  have blunt-ended rounded projections  56  with a cross sectional diameter of about 0.125 inches, while the disc  48  is molded with integrally formed oval niches  57  about 2.5 times in length compared to the diameter of the rounded projections and slightly wider. The projections  56  can be integrally formed or inserted in the casing walls. The niches  37  have rounding side walls from a wider opening to a narrower bottom, and the projections  56  have rounded tips which facilitate the engagement of the ridges  56  in the niches  57 . The disc  48  with its spherical portion  50 , spindle  45  and ridges  56  is molded in one piece of a suitable resinous material. Similarly the casing parts  12 ,  13  are also molded parts, thus reducing the part count over prior constructions. 
   The geometrical layout of the projections  56  and niches  57  is seen in  FIGS. 9 and 10  where a first set of projections  56  is positioned on an interior surface of the transverse wall of the lower casing part  13   a . There is also a second set of projections  56  positioned on an interior surface of the transverse wall on the upper casing part  12   a  as seen in  FIG. 11 . These projections  56  are disposed on radii from a center of the casing parts  12   a ,  13   a . A first set of niches  57  is formed on an upper surface of the disc  48  to receive the projections  56  on the upper casing part  12   a  and a second set of niches  57  is formed on an upper surface of the disc  48  opposite the projections  56  to engage the projections  56  on the lower casing part  13   a.    
   As the disc  48  moves in its wobbly motion, first one projection  56  is engaged in a corresponding niche  57  and the succeeding projections  56  are engaged in corresponding niches  57  around the interior of the metering chamber  27   a  from the inlet  18  to the outlet  19 . With this traction, the disc  48  is capable of absorbing and counteracting the incoming pressure of the fluid which imposes both an axial thrust on the spherical portion  50  and tends to impose a side thrust to rotate the spherical portion  50  and disc  48 . The disc  48  absorbs these forces in a unique manner since it is actuated by the incoming fluid and eliminates the necessity for the utilization of the thrust roller bearing and slot arrangement normally found on the side of the measuring chamber which is directly opposite the partition  20 . 
   This has been a description of the preferred embodiments, but it will be apparent to those with skill in the art to which the invention pertains that various modifications may be made to these specific embodiments without departing from the spirit of the present invention, and that such modifications are intended to be encompassed by the following claims.