Abstrict A flow meter and electrically operable valve assembly having integral
flow meters provide detection of very low water flows, along with
ease of installation and compact packaging for a water supply control
system. The flow detection is particularly useful for systems that
control household water supplies to prevent flooding, but is also
useful in other applications such as agricultural and industrial
systems where low water flow rates must be determined. All of the
controls and features are integrable within a compact package that
occupies essentially the same volume and piping space as a conventional
electrically operable valve.
Claims What is claimed is:
1. A flow meter integrated within a liquid system control device
including a primary flow resisting mechanism disposed within a primary
channel of said liquid system control device and a bypass channel
around said primary channel and said primary flow resisting mechanism,
said flow meter comprising: a movable indicator disposed within
said bypass channel, for detecting flow through said bypass channel,
wherein said primary flow resisting element of said liquid system
control device is a movable flow resisting mechanism having a blocking
position that blocks flow through said primary channel at low levels
of forward pressure differential across said primary flow resisting
mechanism so that forward flows lower than a level of flow required
to move said primary flow resisting mechanism from said blocking
position occur entirely through said bypass channel, and wherein
said movable indicator prevents any flow through said bypass channel
from bypassing said movable indicator, whereby said movable indicator
moves with any forward flow occurring through said liquid system
control device; and a detector for detecting a position of said
movable indicator, whereby any forward flow through said liquid
system control device that moves said movable indicator to a detection
threshold of said detector is detected, which indicates a leakage
through said liquid system control device.
2. The flow meter of claim 1 further comprising a bypass flow
resisting mechanism contacting said moveable indicator when said
flow occurs, whereby displacement of said bypass flow resisting
mechanism is proportional to a force produced by flow through said
bypass channel.
3. The flow meter of claim 1 wherein said movable indicator comprises
a ball within said bypass channel, and wherein said bypass channel
defines a chamber having a diameter larger than a diameter of said
ball wherein said ball may move.
4. The flow meter of claim 1 wherein said detector is a detector
for detecting the proximity of a material having magnetic properties,
and wherein said movable indicator is made from a material having
magnetic properties.
5. The flow meter of claim 1 wherein said liquid system control
device is an electrically operable valve assembly including an electrically
operable valve comprising said primary flow resisting mechanism
disposed between a water supply inlet and a household water supply
outlet and said bypass channel leading from said water supply inlet
to said household water supply outlet.
6. The flow meter of claim 1 wherein said liquid system control
device is an electrically operable valve assembly including an electrically
operable valve comprising said primary flow resisting mechanism
disposed between an internal chamber and a household water supply
outlet and said bypass channel leading from said internal chamber
to said household water supply outlet.
7. The flow meter of claim 1 wherein said liquid system control
device is a backflow preventor.
8. The flow meter of claim 1 wherein said detector is an analog
detector determining a continuous position of said movable indicator.
9. The flow meter of claim 1 wherein said detector is a binary
detector determining that a position of said moveable indicator
has exceeded a predetermined position.
10. The flow meter of claim 1 wherein said flow resisting element
of said liquid system control device is a movable flow resisting
element having a backflow-preventing position that blocks reverse
flow through said main channel, and wherein said movable indicator
cooperates with said bypass channel to prevent reverse leakage through
said bypass channel when said movable indicator is seated at a reverse
flow position.
11. The flow meter of claim 1 and wherein said movable indicator
cooperates with said bypass channel at a maximum forward flow position
to block flow through said bypass channel, whereby said movable
indicator is maintained at said maximum forward flow position when
position when said flow resisting element is open.
12. The flow meter of claim 1 wherein said flow resisting element
includes a force-producing element having a first predetermined
spring constant, wherein said movable indicator includes a second
force-producing element having a second predetermined spring constant,
and wherein said first and second predetermined spring constants
are proportioned such that said second force-producing element is
compressed prior to said first force-producing element, whereby
said movable indicator is moved by flows less that a flow required
to move said flow resisting element from said blocking position,
whereby any amount of forward flow through said flow meter is detected.
Description BACKGROUND OF THE INVENTION
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
Water supply control systems for household use generally require
a measure of water flow, so that water leaks may be detected. Typical
flow meters use a paddle or other device inserted into the liquid
flow. Displacement of the paddle against a restoring force provides
a linear or angular measurement of the flow amount. However, paddle
type flow meters generally cannot measure the low flow rates associated
with slow water leaks.
A water supply control system also generally requires an electrically
operable valve to control water flow and other devices such as a
pressure regulator and backflow preventor. The combination of all
of these devices along with a flow meter makes a very large in-line
installation in a typical water supply control system and requires
a number of connections, each that may be susceptible to failure.
Assembly time is also increased when the devices used are discretely
installed in-line.
Therefore, it would be desirable to provide a flow meter for measuring
low flow rates associated with small leaks. It would further be
desirable to provide a flow meter that may be integrated with other
devices such as electrically controllable valves, backflow preventors
and pressure regulators, whereby fewer interconnects, smaller in-line
installation space and less assembly time is required.
SUMMARY OF THE INVENTION
The above objective of providing a flow meter for measuring low
flow rates that does not require additional in-line space, additional
interconnects and assembly time is achieved in a positive flow meter
that may be constructed integral to an electrically controllable
valve, pressure regulator and backflow preventor. The water system
control device and flow meter are thus incorporated within one housing.
The positive flow meter is integrated in a water control system
valve or backflow preventor that include a main chamber and a bypass
channel. A movable indicator is disposed within the bypass channel
and a position sensor is located near the bypass channel so that
the position of the movable indicator is detectable via the sensor.
The flow meter may further be integrated with a backflow preventor
having a flow resisting element and a position sensor located near
the flow resisting element so that a position of the flow resisting
element may be detected to provide a measure of flow in the forward
direction. A combination of sensors may be used on the flow resisting
element and the bypass channel indicator to provide a high flow/low
flow indication.
The foregoing and other objectives, features, and advantages of
the invention will be apparent from the following, more particular,
description of the preferred embodiment of the invention, as illustrated
in the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
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.
FIG. 4 is a mechanical drawing depicting a cross-section of a backflow
preventer incorporating a flow meter in accordance with an alternative
embodiment of the invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
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 upward, relieving
the compression of 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.
Since the only path to the lower side of lower diaphram 16 is provided
through channel 15 when piston 14 is lowered, water pressure must
be relieved through channel 15 to open electrically operable valve
10. Piston 14 is hollow, and provides a connection from channel
15 (via central aperture 51 of FIG. 2) to a side port channel 24
that extends around the diaphram assemblies and connects to an exit
channel 26 on the outlet side 12 of electrically operable valve
10. Referring to FIG. 2 the path of channel 24 connects through
channels 54 and 56 to channel 17 and venturi 18 of FIG. 1. Flow
in the main channel of electrically operable valve 10 causes a reduced
pressure at venturi 18 pulling water through the above-described
path from the top side of lower diaphram 16 as the valve closes.
A stop ball 53 disposed within channel 54 prevents backflow through
this path.
Solenoid 13 may be a latching-type solenoid, permitting a momentary
pulse to operate electrically operable valve assembly 10. A latching
solenoid is preferred for extending solenoid life and for reducing
power consumption and noise, but a standard solenoid may be preferred
if it is desirable to cut-off water flow when electrical supply
to the assembly fails.
2. Pressure Regulator
Upper diaphram 25 provides a pressure regulator integrated within
electrically operable valve assembly 10. A channel 17 connects to
a venturi 18 that couples the household water outlet side 12 of
electrically operable valve assembly 10 to the lower side of upper
diaphram 25. The pressure supplied through channel 17 to upper diaphram
25 acts against spring 27 that is manually adjustable via turnscrew
28. When the outlet pressure exceeds a level as set by turnscrew
28 adjustment, upper diaphram 25 lifts inner piston 22 raising
gasket assembly 20 restricting the flow through the main channel
of electrically operable valve assembly 10. Thus, a pressure feedback
mechanism is established that regulates the pressure at outlet 12.
3. Flow Meter
A flow meter may be implemented within electrically operable valve
assembly 10 by a sensor 35 mounted near bypass channel 32 inlet.
A ball 34 is mounted within bypass channel 32 and may be made of
a magnetized material or ferromagnetic material for use with a hall
effect sensor. Sensor 35 may be a hall effect sensor, inductive
sensor or other suitable sensor for detecting the proximity of ball
34. The output indication from sensor 35 may be a continuous analog
reading of the position of ball 34 or a binary flow/no-flow indication.
The flow meter implemented by ball 34 and sensor 35 is a positive
flow meter in that any flow through valve assembly 10 will move
ball 34 away from sensor 35 providing measurement of flows much
lower than flow rates detectable with conventional flow meters for
household water supply applications, which typically cannot detect
flows below 0.5 gallons per minute. The positive flow meter permits
detection of low volume water leaks that may cause damage to a structure
without registering a flow at a flow meter detection system. Since
any flow through valve assembly 10 requires a pressure drop between
water supply inlet 11 and household water supply outlet 12 ball
34 will move away from sensor 35 as flow through bypass channel
32. Spring 33 has a very low spring constant and very little force
on ball 34 is required to compress spring 33. When no flow (or back
flow begins to occur), ball 34 will be forced by spring 33 against
seat 36 effectively closing bypass channel 32 to prevent backflow
leakage. Setscrew 37 permits adjustment of the cross-section of
bypass channel 32 providing a means for adjusting the sensitivity
of the flow meter at the factory or after installation. As the channel
cross-section decreases, the amount of force compressing spring
33 for a given flow rate will increase, thus increasing the sensitivity
of the flow meter.
Spring 31 is designed so that gasket assembly 30 will not open
the main valve channel until the sensor 35 detects positive flow
and therefore any flow through electrically operable valve assembly
10 will result in an indication from sensor 35. The above operation
is accomplished by making the spring constant of spring 31 such
that ball 34 will travel past sensor 35 before spring 31 is compressed
to open the main valve channel.
4. Alternative Electrically Operable Valve and Flow Meter 1
Referring now to FIG. 3 an electrically operable valve and flow
meter in accordance with an alternative embodiment of the invention
is depicted. In this embodiment, the pressure regulator is removed
from the embodiment depicted in FIGS. 1 and 2 simplifying the structure
of the assembly. In the depiction, like reference numbers are used
to indicate the corresponding components, the operation of which
is described above for the embodiment of FIGS. 1 and 2. Therefore,
only differences between the assemblies will be described.
Piston 23A is a single sleeve piston operating in similar fashion
to outer piston 23 of FIG. 1. Piston 23A does not have to be hollow,
as inner piston 22 of FIG. 1 was provided to implement pressure
regulation and is therefore not needed in the present embodiment.
Piston 23A is slidably coupled to gasket assembly 30A, which is
operated by diaphram 16 or backpressure from water supply outlet
12 eliminating the need for the separate piston 30 or gasket assembly
20 of FIG. 1. The sliding mount of gasket assembly 30A in conjunction
with spring 31 provides closure of the main channel at the onset
of flow until ball 34 has seated against seat 36 providing proper
operation of the flow meter within the bypass channel. However,
since forward pressure can be applied through channel 32 when the
valve is closed (channel 32 in the embodiment of FIG. 1 is effectively
closed by gasket assembly 20 when the valve is closed), a second
seat 36B is provided for ball 34 in the reverse flow direction,
preventing leakage through the flow meter channel 32 when the valve
is closed. The bottom of seat 363 is provided by a threaded insert
43 in the depicted embodiment. In order for ball 34 to move when
a forward flow is generated through the valve assembly, water must
flow channel 32. Forward flow is provided by a channel passing through
threaded insert 43. Balloon detail 42 depicts the above-described
channel 38 that is cross-drilled through threaded insert 43 to connect
with the hole that is drilled to retain spring 33. When the valve
is closed, water can flow through channel 38 from the center of
spring 33 until ball 34 seats at bottom seat 36B.
5. Alternative Embodiment--Backflow preventor with Flow Meter
Referring now to FIG. 4 a backflow preventor 70 in accordance
with an alternative embodiment of the invention is depicted. Backflow
preventor includes a water supply inlet 72 and a water supply outlet
71 for coupling the backflow preventor to an electrically operable
valve for control of a household water supply. A plunger 74 is slidably
mounted on a piston assembly 73 which includes vanes 72 that permit
the passage of water beyond piston assembly 73. A spring 75 pushes
plunger 74 against a seat, preventing flow of water from water supply
outlet 71 to water supply inlet 72. Flow from water supply inlet
72 to water supply outlet 71 compresses spring 75 and spring 75
can be designed to provide pressure reduction from water supply
inlet 72 to water supply outlet 71 if desirable for a particular
application.
A flow meter is integrated within backflow preventor 70 by a ball
81 and sensor 85 which operate and are constructed as described
above for the flow meter incorporated within the electrically operable
valve asembly 10 of FIG. 1. Spring 82 is compressed by flow through
channel 80 and the spring constant of spring 82 is specified so
that ball 81 will move away from sensor 85 at a flow rate lower
than that required to move plunger 74. A seat 83 prevents backflow
through channel 80 and a setscrew 84 provides adjustment of the
cross section of bypass channel 80 permitting adjustment of the
flow meter sensitivity.
A second flow meter may be incorporated within backflow preventer
70 by incorporating a movable indicator 76 on the end of plunger
74 and detecting the position of movable indicator 76 with a second
sensor 77. Since ball 81 will move at flow rates lower than those
required to move moveable indicator 76 sensor 77 is a "high
flow" indicator with respect to sensor 85 which may provide
a failure indication if sensor 85 is inactive when sensor 77 provides
an indication of flow. Or, sensor 85 and sensor 77 may be used within
a household water control system to provide indication of various
levels of flow. For example, a dripping faucet will activate sensor
85 but will probably not activate sensor 77 while a major plumbing
leak will activate both.
The embodiments of the invention described above disclose an electrically
operable valve with pressure regulation incorporated within one
housing and using common mechanisms between the valve and pressure
regulator. In the alternative embodiment, backflow prevention and
flow rate indication are corporated also within a common housing.
Both embodiments provide a flow meter capable of registering very
low flow rates, so that household leak detection may be accomplished
for very low flow rate leaks. The valve is suitable for use within
the system and method described in the above-incorporated patent
application "METHOD AND SYSTEM FOR CONTROLLING A HOUSEHOLD
WATER SUPPLY", wherein the valve will provide a compact solution
having very high sensitivity to water supply system leaks.
While the invention has been particularly shown and described with
reference to the preferred embodiments thereof, it will be understood
by those skilled in the art that the foregoing and other changes
in form, and details may be made therein without departing from
the spirit and scope of the invention. |