Classifications

• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01F—MEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL; METERING BY VOLUME
  • G01F3/00—Measuring the volume flow of fluids or fluent solid material wherein the fluid passes through the meter in successive and more or less isolated quantities, the meter being driven by the flow
  • G01F3/02—Measuring the volume flow of fluids or fluent solid material wherein the fluid passes through the meter in successive and more or less isolated quantities, the meter being driven by the flow with measuring chambers which expand or contract during measurement
  • G01F3/04—Measuring the volume flow of fluids or fluent solid material wherein the fluid passes through the meter in successive and more or less isolated quantities, the meter being driven by the flow with measuring chambers which expand or contract during measurement having rigid movable walls
  • G01F3/06—Measuring the volume flow of fluids or fluent solid material wherein the fluid passes through the meter in successive and more or less isolated quantities, the meter being driven by the flow with measuring chambers which expand or contract during measurement having rigid movable walls comprising members rotating in a fluid-tight or substantially fluid-tight manner in a housing
  • G01F3/08—Rotary-piston or ring-piston meters

Definitions

• This invention relates to water meters and particularly to volumetric or semi-positive water meters.
• a volumetric water meter comprises an eccentric piston oscillating within a chamber which has inlet and outlet ports.
• the piston is in sealing engagement within the chamber and sweeps a known volume as fluid passes from the inlet to the outlet port. If the movement of the piston is to reflect accurately the flow of fluid through the meter, there must be very close engagement between the piston and the internal wall of the chamber. This can cause difficulty in circumstances where the fluid carries solid particles. It is not unusual, for example, for water supplies to carry occasional particles of grit. These particles will, if trapped between the piston and the internal chamber wall, increase friction and may cause abnormal wear. There is under these circumstances a real risk that the accuracy of the meter will fall below a tolerable level.
• the present invention consists in a water meter comprising a cylindrical chamber having a fluid inlet port and a fluid outlet port and a piston eccentrically disposed within the chamber and having a cylindrical piston wall in sealing engagement with the cylindrical wall of the chamber such that generally cicumferential movement of the piston relative to the chamber sweeps a fixed volume of water passing from the inlet to the outlet port, characterised in that one of the said cylindrical piston wall and the said cylindrical chamber wall is provided with a plurality of recesses spaced circumferentially, each recess opening to the chamber so as to provide a pathway for particulate matter carried by the water, without significant impairment of said sealing engagement.
• flush channel means communicate between said pathway and the fluid outlet port.
• said recesses comprise axially directed grooves.
• said grooves are formed in a radially outwardly directed surface of the piston.
• an axially extending slot which communicates with said recesses downstream of said sealing engagement and which connects with the outlet port to facilitate flushing of particulate matter.
• the most important application of meters according to the present invention is the metering of portable water supplies.
• the recesses may take the form of axially extending grooves in the cylindrical outer surface of the piston. These grooves will preferably extend over the entire or substantially the entire axial length of the piston and will be provided around the entire periphery of the piston. Alternatively, grooves may be formed in that part of the chamber wall which is in sealing engagement with the piston.
• a volumetric water meter has a piston sweeping an annular space betweena cylindrical wall and a cylindrical chamber hub.
• a design choice is made as to which of these engagements serves as the metering seal.
• a further alternative within the present invention provides recesses in either the cylindrical piston wall or the cylindrical chamber hub.
• Figure 1 is an exploded view of a known volumetric water meter
• Figures 2a) to 2d) are a series of diagrams illustrating the manner of operation of the water meter shown in Figure 1 ;
• Figure 3 is a plan view of a piston forming part of a water meter according to one embodiment of the present invention.
• Figure 4 is a portion of Figure 3 shown to an enlarged scale
• Figure 5 is a front view of the piston shown in Figures 3 and 4;
• Figure 6 is a view similar to Figure 3, illustrating the operation
• Figure 7 is a cross-sectional view through a water meter incorporating the piston of Figure 3;
• Figure 8 is a section on line A-A of Figure 7;
• Figure 9 is a perspective view illustrating a modification
• Figure 10 is a view similar to Figure 7 of a meter according to a further embodiment of the present invention.
• Figure 11 is a view in the direction B of Figure 10.
• FIG. 1 r there is shown by way of background a water meter which is presently commercially available from Kent Meters Limited. Detailed description is not felt to be necessary but it will be seen that the arrangement generally consists of a lower housing 10; a chamber 12; a piston 1 ; a shutter 16; a top plate 18; a register 20 and an upper housing 22.
• a half-crescent shaped inlet port 24 is provided in the base of the chamber 12 and is open to the interior of the piston 14. In-flowing water causes the piston to start its semi-rotary oscillatory movement, sliding on the dividing shutter 16. Simultaneously, exhaust water in the remaining part of the piston is being expelled through the half crescent-shaped outlet port 26 in the top plate 18.
• Figure 2c shows the halfway position in which the interior of the piston 14 is cut off from both ports.
• a piston 12 having a cylindrical piston wall 30; an integral, perforate bottom plate 32; and a register-driving boss 34.
• the piston wall 30 has an aperture 36 shaped to receive the shutter 16 in a combined sliding and rocking motion.
• the plate 32 has a cut-away 38 for the same purpose.
• grooves 40 Around substantially the entire outer periphery of the piston wall 30, there are provided grooves 40.
• the cross-sectional shape of these grooves is seen most easily in the increased scale of Figure 4.
• the grooves are parallel to the cylindrical axis and, apart from the region about the aperture 36, are equally spaced.
• the grooves 40 extend over the major portion of the axial length of the piston 12, leaving a land 42 which ensures that there is no direct leakage path from the inlet to the outlet port.
• a relief slot 60 is provided around the point at which the shutter 16 enters the wall of the chamber 12. In a preferred feature of this invention, the relief slot 60 - at the downstream side - is extended to communicate with the outlet port 26.
• Inlet port 24 is provided in the top of the chamber. This enables all water to be freely exhausted from the downstream side of the chamber grooves 40, avoiding an accumulation of grit inside the chamber.
• the described water meter has the following advantageous features :-
• any solid matter is likely to remain in suspension, by virtue of the described turbulence.
• a throughway is created for particles to be flushed out through the outlet port, and v) entrapped water has a cushioning effect reducing friction and lowering wear.
• grooves may be formed in that hub as shown at 126.
• grooves will be formed only at that interface which provides the metering seal; the running gap at the other interface will be increased to the extent that no problem arises with particulate matter.
• the inlet and outlet ports need not necessarily lie at opposite axial ends of the chamber and an arrangement of recesses significantly different from that described may be required to provide the desired passage of solid matter across the seal.
• the inlet and outlet ports may, for example, be spaced circumferentially of the chamber. Such an arrangement is shown in Figures 10 and 1 1 .
• the chamber 212 is provided with a radially directed outlet port 226 and a circumferentially offset inlet port which is not seen in the drawing.
• the piston 214 is provided with grooves 240 in the outer periphery of the piston wall 230. The operation of the piston 214, together with the shutter 216, is analagous with the arrangement described above.
• grooves 242 are provided also in the inner surface of the piston wall 230.
• a flushing well 250 is provided in the chamber 212 to collect particulate matter transported around the swept volume in the piston recesses. As shown in Figure 1 1 this flushing well 250 communicates with the outlet port 226.

Landscapes

• Physics & Mathematics (AREA)
• Fluid Mechanics (AREA)
• General Physics & Mathematics (AREA)
• Measuring Volume Flow (AREA)
• Feeding, Discharge, Calcimining, Fusing, And Gas-Generation Devices (AREA)
• Reciprocating Pumps (AREA)

Applications Claiming Priority (3)

Publications (1)

Family

ID=10714734

Family Applications (1)

Country Status (5)

Cited By (1)

Families Citing this family (18)

Family Cites Families (4)

• 1992
  • 1992-04-29 GB GB929209250A patent/GB9209250D0/en active Pending
• 1993
  • 1993-04-29 AU AU51560/93A patent/AU5156093A/en not_active Abandoned
  • 1993-04-29 EP EP93911886A patent/EP0592660A1/de not_active Withdrawn
  • 1993-04-29 CA CA 2112471 patent/CA2112471A1/en not_active Abandoned
  • 1993-04-29 WO PCT/GB1993/000891 patent/WO1993022631A1/en not_active Ceased

Non-Patent Citations (1)

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