Abstrict A fluid flow meter is provided and comprises a housing having a
fluid inlet and a fluid outlet and a fluid passage for connecting
the inlet with the outlet. The fluid passage further includes an
elongated cylindrical chamber having one end open to the inlet and
the other end open to the outlet while a piston is axially slidably
mounted within this housing chamber and is movable between a first
and second position. The outer periphery of the piston is sealed
with respect to the housing. The piston includes a removable orifice
plate having a fluid port open to the inlet end of the chamber while
a fluid passage formed through the piston fluidly connects the port
with the outlet end of the chamber. A rod is positioned within the
housing and held in place by removable housing end covers. The rod
includes a tapered portion positioned through the port which variably
restricts the port in dependence upon the axial position of the
piston. A resilient member urges the piston towards the inlet end
of the chamber while an indicator is connected to the piston to
provide an exteriorly visible signal of the axial position of the
piston member and thus of the flow through the flow meter. Further,
the piston assembly is constructed as a cartridge assembly so that
the top cover can be removed and a new cartridge assembly installed
quickly and easily. A set point is provided so that the new cartridge
can be quickly zeroed.
Claims I claim:
1. A fluid flow meter comprising:
a housing having a fluid inlet and a fluid outlet radially disposed
in said housing;
fluid passage means formed through said housing for connecting
said inlet with said outlet, said passage means including an elongated
chamber and means connecting one end to the inlet and its other
end to the outlet;
a piston assembly axially slidably mounted in said housing chamber
and movable between a first and a second position;
means for fluidly sealing said piston assembly to said housing;
said piston assembly further comprising an orifice plate having
a fluid port open to the inlet end of said chamber, said orifice
plate being removable from said piston assembly, and means formed
through said piston assembly for fluidly connecting said port to
the outlet end of said chamber;
means for resiliently urging said piston assembly toward the inlet
end of the chamber;
a rod held in said housing and extending axially through at least
a portion of said chamber, said rod having a tapered portion which
extends through said port and variably restricts said port in dependence
upon the axial position of said piston assembly;
means for exteriorly indicating the axial position of the piston
assembly; and
said housing having a removable end cover on an axial end of the
chamber on the side of the piston assembly opposite the resilient
urging means,
said orifice plate being removable from said piston assembly and
removable from said housing without disturbing or replacing said
piston assembly or said rod when said end cover is removed from
said housing whereby said orifice plate can be replaced with another
orifice plate having a different size port to thereby change the
flow range of the flow meter.
2. A fluid flow meter comprising:
a housing having a fluid inlet and a fluid outlet;
fluid passage means formed through said housing for connecting
said inlet with said outlet, said passage means including an elongated
chamber having one end open to the inlet and its other end open
to the outlet;
a piston assembly axially slidably mounted in said housing chamber
and movable between a first and a second position;
means for fluidly sealing said piston assembly to said housing;
said piston assembly further comprising a fluid port open to the
inlet end of said chamber;
means formed through said piston assembly for fluidly connecting
said port to the outlet end of said chamber;
means for resiliently urging said piston assembly toward the inlet
end of the chamber;
a rod held in said housing and extending axially through at least
a portion of said chamber, said rod having a tapered portion which
extends through said port and variably restricts said port in dependence
upon the axial position of said piston assembly;
means for exteriorly indicating the axial position of the piston
assembly; and
said housing having a removable end cover on one axial end of the
chamber through which the piston assembly and attached rod are removable
as a unit and replaceable with a different piston assembly and attached
rod to thereby change the flow range of the flow meter.
3. A fluid flow meter comprising:
a housing having a fluid inlet and a fluid outlet;
fluid passage means formed through said housing for connecting
said inlet with said outlet, said passage means including an elongated
chamber having one end open to the inlet and its other end open
to the outlet;
a piston assembly axially slidably mounted in said housing chamber;
means for fluidly sealing said piston assembly to said housing;
said piston assembly further comprising an orifice plate having
a fluid port open to the inlet end of said chamber, said orifice
plate being removable from said piston assembly, and means formed
through said piston assembly for fluidly connecting said port to
the outlet end of said chamber;
means for resiliently urging said piston assembly toward the inlet
end of the chamber;
a rod held in said housing and extending axially through at least
a portion of said chamber, said rod having a tapered portion which
extends through said port and variably restricts said port in dependence
upon the axial position of said piston assembly;
means for exteriorly indicating the axial position of the piston
assembly; and
said housing having a removable end cover on one axial end of the
chamber through which the orifice plate is removable and replaceable
with another orifice plate having a different size port to thereby
change the flow rate of the flow meter;
said piston assembly further comprising a first piston part and
a second piston part, said orifice plate being secured to said first
piston part, and said piston parts being axially adjacent and coaxially
slidably mounted on said rod;
said fluid connecting means being formed wholly through said first
piston part; and
said second piston part abutting at one end against said first
piston part and including a cavity through which said rod extends,
said resilient means being positioned in said cavity and spring
stop means secured to said rod adjacent the other end of the second
piston part so that said resilient means is entrapped between said
spring stop means and said first piston part.
4. The invention as defined in claim 3 wherein said fluid connecting
means further comprises an interior chamber formed in said first
piston part and open to said port and a plurality of circumferentially
spaced and substantially radially extending fluid passageways formed
through said first piston part, each of said passageways open at
one end to said interior piston chamber and at their other end open
to the outlet end of the housing chamber.
5. The invention as defined in claim 3 wherein said resilient means
comprises a helical spring coaxially disposed around said rod.
6. The invention as defined in claim 3 wherein said indicating
means further comprises a shaft rotatably mounted in said housing,
an elongated lever connected at one end to the shaft and at its
other end to said piston assembly so that axial displacement of
said piston assembly proportionately rotates said shaft, and means
connected to said shaft for indicating the rotation of said shaft.
7. The invention as defined in claim 6 wherein said means for indicating
the rotation of the shaft comprises a needle secured to said shaft.
8. The invention as defined in claim 6 and further comprising means
for activating an electric switch when said shaft achieves a predetermined
rotational position.
9. The invention as defined in claim 8 wherein said activating
means further comprises a cam secured to said shaft and a cam follower
secured to said switch, the position of said cam follower controlling
the activation of the switch.
10. A fluid flow meter comprising:
a housing having a fluid inlet and a fluid outlet;
fluid passage means formed through said housing for connecting
said inlet with said outlet, said passage means including an elongated
chamber having one end open to the inlet and its other end open
to the outlet;
a piston assembly axially slidably mounted in said housing chamber;
means for fluidly sealing said piston assembly to said housing;
means formed through said piston assembly for fluidly connecting
said port to the outlet end of said chamber;
means for resiliently urging said piston assembly toward the inlet
end of the chamber;
a rod held in said housing and extending axially through at least
a portion of said chamber, said rod having a tapered portion which
extends through said port and variably restricts said port in dependence
upon the axial position of said piston assembly;
means for exteriorly indicating the axial position of the piston
assembly; and
said piston assembly further comprising a first piston part and
a second piston part, said piston parts being axially adjacent and
coaxially slidably mounted on said rod;
said second piston part abutting at one end against said first
piston part and including a cavity through which said rod extends,
said resilient means being positioned in said cavity and spring
stop means secured to said rod adjacent the other end of the second
piston part so that said resilient means is entrapped between said
spring stop means and said first piston part.
11. The invention as defined in claim 10 wherein said resilient
means comprises a helical spring coaxially disposed around said
rod.
12. The invention as defined in claim 10 and further comprising
fluid filtering means operatively disposed between said fluid inlet
and said housing chamber.
13. The invention as defined in claim 12 wherein said fluid filtering
means further comprises a filter element sandwiched in between said
end cover and a portion of said housing.
14. The invention as defined in claim 10 wherein said fluid connecting
means are formed wholly through said first piston part.
Description BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to fluid flow meters and,
more particularly, to a fluid flow meter in which the fluid flow
range can be easily varied.
2. Description of the Prior Art
There have been a number of previously known fluid flow meters
having a housing with a fluid inlet, a fluid outlet and means for
measuring and exteriorly indicating the fluid flow from the inlet
and to the outlet. For example, in one type of previously known
fluid flow meters, a semicircular vane cooperates with a hemispherical
shaped housing disposed between the fluid inlet and the fluid outlet.
Rotation of the vane provides a variable size opening between the
vane and the housing while resilient means urges the vane towards
a closed position. The rotation of the vane within the housing,
caused by the fluid flow into the housing inlet, is used to provide
an exteriorly visible signal of the vane rotation and, thus, of
the fluid flow rate through the housing.
In a still further type of fluid flow meter, a tapered needle cooperates
with a port which fluidly connects the inlet to the outlet. In addition,
a piston is axially slidably mounted within the housing and secured
to either the tapered needle or the port so that the displacement
of the piston caused by the fluid flow through the flow meter variably
opens the port in dependence upon the flow rate. Electrical and/or
mechanical indicating means are attached to the piston member to
provide a signal of the axial displacement of the piston and hence
of the fluid flow rate through the flow meter.
One disadvantage of these previously known flow meters is that
the flow range for the flow meter is preset and nonadjustable after
assembly of the flow meter. Consequently, if a different flow range
for the flow meter is desired, it is necessary to replace the entire
flow meter.
SUMMARY OF THE PRESENT INVENTION
The present invention overcomes the above mentioned disadvantages
of these previously known flow meters by providing a flow meter
in which the flow range of the flow meter can be simply and rapidly
adjusted or changed in the field as desired. Moreover, as will hereafter
become apparent, the flow meter of the present invention is of simple
and yet durable construction.
In brief, the flow meter according to the present invention comprises
a housing having a fluid inlet, a fluid outlet and fluid passage
means for fluidly connecting the inlet to the outlet. The fluid
passage means also includes an elongated chamber, preferably cylindrical
in shape, having one end open to the inlet and its other end open
to the outlet.
A piston assembly is axially slidably mounted within the housing
chamber and movable between a first position and a second position.
An O-ring fluidly seals the outer periphery of the piston assembly
to the chamber wall while a helical spring urges the piston towards
the inlet end of the housing chamber.
The piston assembly further includes an orifice plate having a
fluid port open to the inlet end of the fluid chamber. A fluid passageway
is formed through the piston assembly for connecting the fluid port
to the outlet end of the housing chamber. A rod is also held to
the housing covers and extends coaxially through the housing chamber
and thus coaxially through the piston assembly and its fluid port.
Moreover, the rod includes a tapered portion which is positioned
within the port as the piston assembly moves between its first and
second position to thereby variably restrict the port in dependence
upon the axial position of the piston assembly.
In operation, fluid flow into the housing inlet urges the piston
assembly toward the outlet end of the fluid chamber and against
the force of the helical spring thus increasing the effective area
of the piston assembly port in an amount proportional to the fluid
flow through the flow meter. The axial displacement of the piston
in turn is exteriorly visibly indicated by means of a needle mechanically
linked to the piston.
The flow meter housing further includes a removable end cover plate
through which the orifice plate can be removed from the housing
and replaced with an orifice plate having a different size port.
The replacement of the orifice plate with a different size port
in effect changes the effective flow range of the flow meter in
accordance with the size of the port. Alternatively, the entire
piston assembly can be replaced to change the flow range of the
flow meter.
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 longitudinal sectional view illustrating the flow meter
according to the present invention;
FIG. 2 is a cross-sectional view taken substantially along line
2--2 in FIG. 1;
FIG. 3 is a fragmentary sectional view illustrating the operation
of the flow meter of the present invention;
FIG. 4 is a fragmentary sectional view illustrating the flow meter
of the present invention adjusted to a different flow range;
FIG. 5 is a partial sectional top view illustrating the indicating
means for the flow meter; and
FIG. 6 is a view taken substantially along line 6--6 in FIG. 5.
DETAILED DESCRIPTION OF THE PRESENT INVENTION
With reference first to FIG. 1 the flow meter 10 according to
the present invention is thereshown and comprises a housing 12 having
a fluid inlet 14 and a fluid outlet 16. Both the housing inlet 14
and outlet 16 are internally threaded for connection with conventional
fluid fittings (not shown) which in turn are connected to a fluid
system (not shown).
Referring now to FIGS. 1 and 2 the housing 12 further comprises
a tubular and cylindrical outer housing wall 18 which is open at
both ends 19 and 20. The housing 12 thus forms an elongated cylindrical
chamber 24 having one end fluidly connected by a fluid passageway
26 to the fluid outlet. Similarly, the opposite end of the fluid
chamber 24 is open to the fluid inlet 14 via a cylindrical fluid
chamber 28 and a fluid passageway 29.
The end 19 of the housing 12 is covered by a closure cap 32 and
secured in place by bolts 34. Appropriate seal means 36 are provided
between the closure cap 32 and the housing 12 in order to prevent
fluid leakage. Similarly, the opposite end 20 of the housing 12
is covered by an end cover 40 and removably secured to the housing
12 by bolts 42. Appropriate sealing means, such as an O-ring 44
are provided between the end 20 of the housing 12 and the closure
plate 40 to prevent fluid leakage from the housing 12.
An elongated rod 50 extends coaxially through the housing chamber
24 and has one end positioned within a recess 52 in the closure
cap 32. Similarly, the opposite end of the rod 50 is positioned
within a recess 58 in the cover 40. The cover 40 however, can be
readily removed from the rod 50 for a reason to become hereafter
apparent. Moreover, the rod 50 includes a tapered portion 59 which
tapers radially inwardly for a distance along a mid portion of the
rod 50.
A piston assembly 60 is axially slidably mounted within the housing
chamber 24 and includes a first piston part 62 having a body 63
and a second piston part 64. The piston parts 62 and 64 are coaxial
with each other but axially adjacent so that one end 66 of the second
piston part 64 abuts against one end 68 of the first piston part
62.
Still referring to FIG. 1 a fluid seal ring 70 such as an O-ring,
is secured to the outer periphery of the first piston part 62 and
fluidly seals the first piston part 62 to the interior walls 72
of the housing chamber 24. The seal 70 however, permits the first
housing part 62 to axially slide along the housing chamber 24.
The first piston part 62 further includes an orifice plate 73 having
a fluid port 74 and which is removably secured to the piston body
63 by screws 75. The fluid port 74 is open to the fluid chamber
28 and thus to the inlet 14. A fluid chamber 78 within the interior
of the first piston part 62 in conjunction with the plurality of
circumferentially spaced and substantially radially extending fluid
passageway 76 (FIGS. 1 and 2) fluidly connects the port 74 to the
fluid outlet 16 of the housing chamber 24.
The first piston part 62 further includes a through bore 80 which
is coaxial with the port 74. The rod 50 extends coaxially through
the port 74 and through bore 80 so that the tapered portion 59 of
the rod 50 is disposed in between the through bore 80 and the port
74. The tapered portion 59 of the road 50 tapers radially inwardly
from the orifice plate 73 and to the opposite end of the chamber
78. In addition, a tubular stop 71 limits the downward travel of
the piston assembly 60.
The second piston part 64 is cylindrical in shape and includes
a longitudinal recess 82 greater in diameter than the rod 50 thus
forming an annular chamber 83 between the second piston part 64
and the rod 50. The rod 50 extends coaxially through the recess
82 and also through a bore 83 formed at the other end 86 of the
second piston part 64.
A helical spring 88 is positioned within the annular chamber 83
and abuts at one end 89 against a spring retainer 90 secured to
the rod 50 by a snap ring 91. At its other end, the spring 88 abuts
against a washer 92 positioned around the rod 50. The end 66 of
the second piston part 64 is positioned within a cylindrical cavity
79 at the upper end 68 of the first piston part 62 and the piston
parts 62 and 64 are then secured together by sets of screws 93.
By this construction the entire piston assembly 60 can shift upwardly
(as viewed in the drawing) along the rod 50 from the position shown
in FIG. 1 and to the position shown in FIG. 3. In doing so, the
piston assembly 60 will compress the spring 88 between the spring
retainer 90 and the washer 92.
With reference now to FIG. 1 in the preferred form of the invention,
a tubular cylindrical filter element 96 is positioned within the
fluid chamber 28. The filter element 96 is spaced radially inwardly
from the outer walls of the chamber 28 and thus defines an annular
chamber 97 which is open to the inlet passageway 29. The filter
element 96 is thus effectively positioned in between the fluid inlet
14 and the piston assembly 60. The filter element 96 prevents debris
which may be contained within the influent from entering into and
possibly clogging the fluid passageways formed through the first
piston part 62. Moreover, the filter element 96 can be easily removed
for cleaning and/or replacement by simply removing the end cover
40 as required.
With reference now to FIGS. 1 5 and 6 a lever arm 98 is perpendicularly
secured to a shaft 100 at one end 102 and, at its other end has
a roller 104 which abuts against the free end 86 of the second piston
part 64. The shaft 100 is rotatably journalled within the housing
12 and extends into an indicator housing 150 secured to the housing
12.
An indicator assembly 152 is secured to the other end of the shaft
100 within the interior of the indicator housing 150. The indicator
assembly 152 includes a cam 154 and a stem 156 which is coaxial
with the shaft 100. An indicator needle 106 is secured by a screw
158 to the stem 156 so that the needle 106 stem 156 and cam 154
rotate in unison with the shaft 100.
An indicia plate 160 having an appropriate scale 162 is mounted
within the indicator housing 150 so that upon rotation of the shaft
100 the needle 106 sweeps across the scale 162 and provides an
exteriorly visible indication of the rotation of the shaft 100.
In addition, the cam 154 has a cam surface 164 which cooperates
with a cam follower 166. The cam follower 166 in turn is mounted
to a switch 168 so that when the needle 106 reaches a predetermined
position, the switch 168 is activated. The switch 168 can be connected,
for example, to an alarm system.
Referring now to FIGS. 1 and 3 in operation, fluid flow into the
housing inlet 14 passes into the annular chamber 97 through the
filter element 96 and to the opposite end of the housing chamber
24. This fluid flow urges the piston assembly 60 upwardly as shown
in FIG. 3 against the force of the helical spring 88 and, in doing
so, increases the effective area of the fluid port 74 due to the
tapered portion 59 of the rod 50. Fluid flow through the port 74
enters into the piston chamber 78 passes out through the fluid
passageways 76 and ultimately passes out through the housing outlet
16 via passageway 26. Moreover, as the volumetric fluid flow through
the flow meter 10 increases, it will likewise increase the axial
displacement of the piston assembly 60 by an increasing amount until
the open area between the port 74 and the tapered portion 59 of
the rod 50 is sufficient to accommodate the fluid flow. The axial
displacement of the piston assembly 60 in turn rotates the shaft
100 with its attached needle 106 via the lever 98. The position
of the needle 106 on the scale 162 is proportional to the axial
position of the piston assembly 60 and thus proportional to the
volumetric flow rate through the flow meter 10.
Referring now to FIG. 4 the flow range of the flow meter 10 however,
can be rapidly and easily adjusted as desired by removing the cover
plate 40 and thereafter removing the orifice plate 73 from the housing
12. Thereafter, a new orifice plate 73' having a different size
port 74 is secured to the body 63 of the first piston part 62 and
the cover 40 is then reassembled to the housing 12. The provision
of a new orifice plate 73' with a larger diameter port 74 would,
in effect, reset the flow range for the flow meter 10 to a higher
range since no or only minimal axial displacement of the piston
assembly 60 would occur until a relatively higher flow rate through
the flow meter is present. Conversely, the flow range for the flow
meter 10 could be reduced to a lower range by substituting another
orifice plate 73" having a port 74 of a smaller diameter.
Alternatively, the entire piston assembly 60 with its attached
rod 50 can be removed from the housing 12 after removal of the end
cover 40 and replaced with a new piston assembly 60 and rod 50 in
order to change the flow range of the flowmeter 10. The spring constant
and compression of the helical spring 88 the taper of the rod tapered
portion 59 and the size of the port 74 all affect the flow range
of the flow meter 10. The replacement of the entire piston assembly
60 with its attached rod 50 is particularly advantageous when the
flow range of the flow meter is to be changed in the field, i.e.
after the flow meter 10 has been installed in a fluid system. In
this case, the piston assembly 60 can be assembled and accurately
calibrated at the factory and then easily, simply and rapidly installed
in the field.
From the foregoing, it can be seen that the flow meter 10 according
to the present invention provides a novel flow meter which is simple
and relatively inexpensive in construction. Moreover, since the
flow range of the flow meter 10 can be readily and simply varied
by merely replacing the orifice plate 73 the flow meter 10 can
be readily adapted for virtually any desired fluid flow range.
Having described my invention, however, many modifications thereto
will become apparent to those skilled in the art to which the invention
pertains without deviation from the spirit of the invention as defined
by the scope of the appended claims. |