Positive flow meter

#1. Field of the Invention

#The present invention relates generally to liquid flow meters, and more specifically, to a positive flow meter for incorporation within an electrically operable valve assembly for controlling a water supply.

#2. Background of the Invention

#FIG. 1 is a mechanical drawing depicting a cross-section of an electrically operable valve assembly incorporating a flow meter in accordance with an embodiment of the invention.

#FIG. 2 is a mechanical drawing depicting a top view of the electrically operable valve assembly of FIG. 1.

#FIG. 3 is a mechanical drawing depicting a cross-section of an electrically operable valve assembly incorporating a flow meter in accordance with an alternative embodiment of the invention.

#1. Electrically Operable Valve

#Referring now to the figures and in particular to FIG. 1, an electrically operable valve assembly 10 in accordance with an embodiment of the present invention is depicted. A water supply inlet 11 provides a connection to a water supply system such as a city water main connection. A household water supply outlet 12 provides connection to a household water supply system. In the depicted embodiment, electrically operable valve assembly 10 includes a backflow preventor, which prevents any backflow of water to the water supply. The backflow preventor comprises a piston 30 and spring 31 that prevent the flow of water when back water pressure moves piston 30 to compress spring 31. Alternatively a ball 30A may be used in place of piston 30, with the ball mounted above spring 31. Alternatively, as shown in balloon 40, a ball 30B may be used in place of piston 30, with the ball mounted above a spring 31A. The backflow preventor device is closely coupled to the operation of an integral flow meter, which will be described in further detail below. The backflow preventor device is closely coupled to the operation of an integral flow meter, which will be described in further detail below.

#Control of electrically operable valve assembly 10 is provided by a piston-mounted gasket assembly 20 that shuts off the main water channel from water supply inlet 11 to household water supply outlet 12. Gasket assembly 20 is slidably mounted on an outer piston 23 that surrounds an inner piston 22. Outer piston 23 is mechanically coupled to a lower diaphram 16. Electrically operable valve assembly is closed by water pressure on the lower side of lower diaphram 16 causing outer piston 23 to move gasket assembly 20 to force the gasket against seat 21. The water pressure on the lower side of lower diaphram 16 is supplied by a channel 15 that receives flow when a piston 14 coupled to electrical solenoid 13 is in the raised position. Referring momentarily to FIG. 2, channel 15 receives flow from central aperture 51 which in turn receives flow from peripheral aperture 55 when piston 14 is raised (an o-ring or washer is provided at the end of piston 14 to provide a seal). Peripheral aperture 55 is coupled to water supply inlet 11 and thus provides a source of pressure higher than household water supply outlet 12.