Abstrict A bypass valve assembly is disclosed for use with a fluid flow
meter of the type having a housing, an inlet, an outlet, a fluid
passage which fluidly connects the inlet to the outlet and a flow
rate responsive member within the fluid passage. The bypass valve
assembly comprises a tubular body open at one end in which is secured
to the flow meter housing so that the open end of the tube registers
with the flow meter inlet. A valve member is contained within the
tube and is urged to a closed position by a helical spring. In its
closed position, the valve member directs all of the influent to
the flow meter through the passage. When the fluid flow rate into
the flow meter exceeds a predetermined amount, the valve member
moves to an open position against the force of the helical spring
thus bypassing the influent directly to the flow meter outlet.
Claims I claim:
1. In a fluid flow meter having a housing, a meter inlet, a meter
outlet, fluid passage means formed in said housing for fluidly connecting
said meter inlet to said meter outlet, and a flow rate responsive
member contained in said fluid passage means, the improvement therein
comprising,
an elongated valve body having an elongated axial bore,
a fluid passageway formed in said body, said fluid passageway having
an inlet end and an outlet end, said axial bore forming a portion
of said fluid passageway,
means for detachably threadably securing said body to said housing
so that said axial bore in said valve body is axially aligned with
said flow meter inlet and so that said fluid passageway inlet end
is open to said flow meter inlet and said fluid passageway outlet
end is open directly to said meter outlet whereby said fluid passageway
bypasses said flow rate responsive member,
a valve member carried within said body and axially movable within
said valve body bore between an open position in which said valve
member establishes fluid communication between the ends of said
fluid passageway and a closed position in which said valve member
prevents fluid flow between said ends of said passageway, said valve
member including an impingement surface adjacent the inlet end of
said fluid passageway when said valve member is in said closed position
and said impingement surface facing said meter inlet,
means for moving said valve member to said closed position when
fluid flow into said flow meter inlet is less than a predetermined
rate;
wherein said fluid passage means comprises an inlet fluid passage
formed in said housing and extending substantially perpendicular
to said meter inlet,
wherein said impingement surface is disposed closely adjacent said
flow meter inlet; and
wherein said impingement surface has a cross-sectional area substantially
the same as that of said meter inlet so that influent through said
meter inlet directly and perpendicularly impinges upon said impingement
surface of said valve member and causes movement of said valve member
in response to the rate of said influent flow.
2. The invention as defined in claim 1 wherein said fluid passageway
comprises at least one radial port formed through said valve member
body.
3. The invention as defined in claim 1 and comprising an elongated
rod secured at one end to said valve member and having its other
end slidably mounted in a bore at an end of said valve member body
most spaced from said meter inlet.
4. The invention as defined in claim 3 wherein said moving means
comprises a compression spring entrapped between said valve member
and the end of said body most spaced from said meter inlet.
Description BACKGROUND OF THE INVENTION
I. Field of the Invention
The present invention relates generally to valve assemblies and,
more particularly, to a bypass valve assembly for a fluid flow meter.
II. Description of the Prior Art
There are a number of different types of fluid flow meters. In
general, however, fluid flow meters comprise a housing having an
inlet, an outlet and a fluid passage formed through the housing
for fluidly connecting the inlet to the outlet. A flow responsive
member is mounted within the housing in series with the fluid passage
so that the position of the flow responsive member varies in accordance
with the fluid flow rate through the flow meter. Indicator means
provide an external signal of the position of the flow response
member and thus of the fluid flow rate.
Flow meters are conventionally designed to operate over a predetermined
range of fluid flow rates. Furthermore, if the maximum fluid flow
rate for the flow meter is exceeded, particularly by a large amount,
the flow meter is oftentimes damaged thus requiring expensive repair
and/or replacement.
For many applications, however, the user of the flow meter is desirous
only of determining when the fluid flow rate falls below a predetermined
and relatively low flow rate. Such low flow rates are typically
indicative of a clogged system or other malfunction of the fluid
system. At the same time, however, the flow meter must be capable
of operating under relatively high fluid flow rates without damaging
the flow meter although the actual flow rate above the predetermined
minimum flow rate is unimportant.
For such fluid applications, the use of a flow meter having a relatively
high fluid flow range has not proven wholly satisfactory. First,
flow meters with high flow ranges are relatively expensive in construction
and thus uneconomical for the user who desires to determine only
when the flow rate falls below a predetermined minimum amount. Secondly,
the accuracy of many flow meters decreases proportionately with
the range of fluid flow rates of the flow meter. Thus, a flow meter
with a very high flow range is incapable of accurately measuring
relatively low fluid flow rates.
SUMMARY OF THE PRESENT INVENTION
The present invention provides a bypass valve assembly which overcomes
all of the above mentioned disadvantages.
In brief, the bypass valve assembly of the present invention is
designed for use with a conventional fluid flow meter. Such a fluid
flow meter comprises a housing having an inlet, an outlet and a
fluid passage formed through the housing for fluidly connecting
the inlet to the outlet. A flow responsive member is positioned
within the fluid passage and the position of the flow responsive
member varies in dependence upon the fluid flow rate through the
flow meter passage. An indicator provides an external signal of
the position of the flow responsive member and thus of the fluid
flow rate.
In the preferred form of the invention, the bypass valve assembly
of the present invention comprises a tube open at one end and which
is secured to the housing so that the open end of the tube is aligned
with and open to the flow meter inlet. Consequently, influent to
the flow meter inlet would normally pass into the interior of the
tube. At least one and preferably a plurality of radial ports are
formed through the tube at a position spaced from its open end and
these radial ports intersect and are open to the interior of the
tube. In addition, these radial ports are in fluid communication
with the flow meter passage at a position between the flow responsive
member and the flow meter outlet.
A valve member is longitudinally slidably mounted within the interior
of the tube. The valve member is normally urged towards a closed
position by a spring wherein the valve member extends across the
interior of the tube in between the radial ports and open end of
the tube. Consequently, in its closed position, the valve member
prevents fluid flow through the tube and instead directs the influent
to the flow meter inlet through the flow meter passage. When the
valve member is in its closed position, the flow meter operates
in its normal fashion and the true fluid flow rate through the fluid
meter is displayed by the flow meter indicator means.
When the flow rate of the influent exceeds a predetermined amount,
the valve member compresses against the force of the spring thus
establishing fluid communication from the open end of the tube and
to the radial ports. In doing so, a portion of the influent bypasses
directly from the flow meter inlet and to the flow meter outlet.
The valve member will remain in its open position as long as the
flow rate to the flow meter inlet exceeds the predetermined flow
rate amount.
BRIEF DESCRIPTION OF THE DRAWING
A better understanding of the present invention will be had upon
reference to the following detailed description when read in conjunction
with the accompanying drawing, wherein like reference characters
refer to like parts throughout the several views, and in which:
FIG. 1 is a sectional view illustrating a flow meter utilizing
a preferred embodiment of the bypass valve assembly of the present
invention;
FIG. 2 is a cross sectional view of the preferred embodiment of
the bypass valve assembly and enlarged for clarity;
FIG. 3 is a cross sectional view taken substantially along line
3--3 in FIG. 2; and
FIG. 4 is a partial sectional view similar to FIG. 1 but illustrating
the bypass valve assembly in its open position.
DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT OF THE PRESENT INVENTION
With reference first to FIG. 1 a flow meter 10 is thereshown having
a housing 12 which defines an interior cylindrical chamber 14. A
flow responsive member 16 such as a piston, is longitudinally slidably
mounted within the chamber 14 while indicating means 18 provide
an exteriorly visible signal of the axial position of the flow responsive
member 16 within the chamber 14.
An inlet 20 on the housing 12 fluidly communicates through passgeways
22 24 and 26 to one side of the flow responsive member 16. The
flow responsive member 16 includes a radial passageway 28 and an
interior bore 30 which, together, establish fluid communication
from the passageway 26 and to a ported plate 32 carried by the flow
responsive member 16.
The ported plate 32 cooperates with a tapered rod 34 to form an
opening 35 between the interior bore 30 of the flow responsive member
16 and an upper subchamber 36 formed above the member 16. The area
of the opening 35 varies with the axial position of the flow responsive
member 16 and a spring 37 urges the member 16 in the direction opposite
from the fluid flow through the opening 35. An outlet 38 on the
flow meter housing 12 is open to the subchamber 36.
The flow meter passageways 22 24 and 26 together with the cross
passage 28 bore 30 and opening 35 form a fluid passage for fluidly
connecting the flow meter inlet 20 to the outlet 38. Consequently,
the flow responsive member 16 is fluidly mounted in series with
the fluid passage means so that fluid flow from the inlet 20 and
to the outlet 38 normally flows through the bore 30 of the flow
responsive member 16 and through the opening 35. The position of
the flow responsive member 16 within the housing chamber 14 is thus
indicative of the flow rate through the flow meter 10 and this flow
is displayed exteriorly of the flow meter housing 12 by the indicator
means 18.
The foregoing description of the flow meter 10 is by way of example
only and is presented only for clarity and completeness. As will
become shortly apparent, the bypass valve assembly according to
the present invention can be used with flow meter of different constructions
and utilizing different types of flow responsive members.
With reference now to FIG. 2 a preferred embodiment of the bypass
valve assembly 42 of the present invention is thereshown and comprises
a body 44 which is tubular and cylindrical in shape. The body 44
is open at one end 46 and has an axial bore 48 formed through its
other end 50. The body 44 thus forms an interior cylindrical chamber
52 and a plurality of circumferentially spaced radial ports 51 are
formed through the body 44 and open to the chamber 52 at a position
axially spaced from the open end 46 of the body 44.
A disc shaped valve member 54 having an axial throughbore 56 is
axially slidably mounted within the body chamber 52. The outside
diameter of the valve member 54 is substantially the same or slightly
less than the diameter of the body chamber 52 so that the valve
member 54 extends substantially entirely across the body chamber
52.
An elongated cylindrical rod 58 having an enlarged head 60 at one
end is inserted through the valve member bore 56 and the bore 48
at the end 50 of the body 44 so that the enlarged head 60 is positioned
between the valve member 54 and the open end 46 of the body 44.
The rod 58 is dimensioned so that, with the valve member 54 positioned
in between the open end 46 of the body 44 and the radial ports 51
a portion 62 of the rod 58 extends outwardly from the end 50 of
the body 44. A compression spring 64 is contained within the body
chamber 52 in between the valve member 54 and the end 50 of the
body 44 and urges the valve member 54 toward the open end 46 of
the body 44. A retainer 66 is secured to the rod portion 62 to limit
the travel of the valve member 54 to a position in between the ports
51 and open end 46 of the body 44.
With reference now to FIGS. 1 and 2 the body 44 includes an externally
threaded portion 68 adjacent the open end 46 of the body 44. This
threaded portion 68 threadably cooperates with an internally threaded
bore 70 (FIG. 1) in the flow meter housing 12 and the bore 70 is
both fluidly open to and aligned with the flow meter inlet 20. With
the bypass valve assembly 42 secured to the flow meter housing 12
as shown in FIG. 1 the influent to the flow meter inlet 20 will
impact upon the valve member 54. At the same time, the radial ports
51 are open to the subchamber 36 and thus open to the flow meter
fluid passage at a position in between the flow responsive member
16 and the outlet 38. Furthermore, with the bypass valve assembly
42 secured to the flow meter housing 12 the bypass valve assembly
chamber 52 forms a passageway with the open end 46 of the chamber
52 forming an inlet end of the passageway and the radial ports 51
forming an outlet end of the passageway.
With reference to FIG. 1 in operation and during relatively low
fluid flow rates into the housing inlet 20 the compression spring
64 maintains the valve member 54 in a closed position, i.e., between
the open end 46 of the body 44 and the radial ports 51. In its closed
position, the valve member 54 prevents fluid flow through the bypass
valve assembly 42 so that all of fluid flow into the housing inlet
20 passes through the flow meter passage 22. In doing so, the fluid
flow axially displaces the flow responsive member 16 which in turn
actuates the indicator means 18 to display true fluid flow rate
through the flow meter 10.
With reference now to FIG. 4 when the fluid flow rate of the influent
to the flow meter 10 exceeds a predetermined rate, as determined
by the helical spring 37 the bypass valve member 54 retracts within
the body chamber 52 to its open position. In its open position,
the valve member 54 uncovers the radial ports 51 thus establishing
fluid communication between the open end 46 of the body 44 and the
radial ports 51. In its open position, the bypass valve assembly
42 fluidly connects the flow meter inlet 20 to the flow meter outlet
38 thus bypassing flow responsive member 16. During the bypassing
condition, the flow rate indicated by the indicator means 18 will
not be accurate. However, for many flow meter applications, the
user is desirous only of detecting when the flow rate falls below
a predetermined rate while the actual measurement of the flow rate
above that predetermined rate is unimportant.
Having described my invention, however, many modifications thereto
will become apparent to those skilled in the art to which it pertains
without deviation from the spirit of the invention as defined by
the scope of the appended claims. |