Note: Descriptions are shown in the official language in which they were submitted.
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PISTON GUIDE FOR PISTON-TYPE FLUSHOMETER
The Field of the Invention
[0002] The present invention relates to guide configuration for piston-type
flush valves. U.S.
Patents 5,881,993 and 4,261,545, among other patents, all owned by Sloan Valve
Company,
show piston-operated flush valves for use in flushing toilets and urinals. In
each of these patents
the piston has an exterior seal which bears against the inside wall of the
flush valve cover. The
present invention adds a piston having an enlarged skirt which reduces the
flow of water through
the annular area of the valve.
Summary of the Invention
[0003] The present invention relates to piston-operated flush valves for use
in connection
primarily with urinals, and more specifically, to an improvement in the form
of a piston having a
guide configuration that controls delivery of water to a plumbing fixture. In
a water closet
present standards call for a water usage of 1.6 gallons per flush. Because
water closets require a
big crash of water at the outset of a flush, the flow rate required is on the
order of 50 gallons per
minute. Urinals are now intended to have a water usage of about .5 to 1.0
gallons per flush.
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However, because urinals require neither the high initial flow rate nor the
refill that water closets
do, the flow rate for a urinal flush can be about 5 to 10 gallons per minute
and the flow rate
profile can be more uniform.
[0004] A primary purpose of the invention is a piston-type flush valve for the
use described in
which the piston has an improved guide configuration to reduce flow through
the valve.
[0005] Another purpose of the invention is a flush valve as described having a
piston which
both reduces the flow and makes the flow rate profile more uniform.
[0006] Another purpose of the invention is a flush valve as described in which
the piston
design produces lower flow which in turn which will reduce the creation of
back pressure.
[0007] A further purpose of the invention is a flush valve as described in
which the reduced
flow rate allows the use of a larger bypass, while still obtaining a lower
flow appropriate for a
urinal.
[0008] Yet another purpose of the invention is to provide a flush valve as
described in which
the piston design reduces turbulence and prevents water impingement on the
relief valve stem,
which in turn reduces flush volume variation.
[0009] Still another purpose of the invention, is a flush valve as described
including a skirt and
rib combination that reduces the flow rate across the guide and main seat to
reduce the flush
volume. The ribs act as guides allowing the skirt diameter to be smaller than
would otherwise be
required, which allows larger debris to pass through. This reduces the chances
that debris will
cause jamming of the piston.
[0010] Another purpose of the invention is a flush valve as described in which
a longer skirt
on the piston further reduces the window opening thereby reducing the flush
volume.
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[0011] These and other desired benefits of the invention, including
combinations of features
thereof, will become apparent from the following description. It will be
understood, however,
that a device could still appropriate the claimed invention without
accomplishing each and every
one of these desired benefits, including those gleaned from the following
description. The
appended claims, not these desired benefits, define the subject matter of the
invention.
Brief Description of the Drawings
[0012] Fig. 1 is a vertical section through a flush valve of the present
invention.
[0013] Fig. 2 is an enlarged partial section showing the connection between
the flush valve
body, the inner cover and the outer cover.
[0014] Fig. 3 is an enlarged partial section illustrating the relationships
among the valve body
and its water passage, the main seat assembly, and the piston, with the
actuator assembly and
relief valve removed for clarity.
[0015] Fig. 4 is a side elevation view of the inner cover.
[0016] Fig. 5 is a bottom plan view of the inner cover.
[0017] Fig. 6 is a section taken along line 6-6 of Fig. 5.
[0018] Fig. 7 is an enlarged detail section of the flange and seal of the
inner cover.
[0019] Fig. 8 is a partial section taken along line 8-8 of Fig. 5.
[0020] Fig. 9 is a top plan view of the main seat assembly.
[0021] Fig. 10 is a section taken along line 10-10 of Fig. 9.
[0022] Fig. 11 is an enlarged detail section of the sealing portion of the
main seat assembly.
[0023] Fig. 12 is a bottom plan view of the main seat assembly.
[0024] Fig. 13 is a partial enlarged side elevation view of the main seat
assembly showing one
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of the lockout lugs.
[0025] Fig. 14 is a partial enlarged side elevation view of the main seat.
[0026] Fig. 15 is a partial enlarged section of the main seat assembly showing
an extension on
one of the lockout lugs.
[0027] Fig. 16 is a top plan view of the piston of the present invention.
[0028] Fig. 17 is a side elevation view of the piston.
[0029] Fig. 18 is a bottom plan view of the piston.
[0030] Fig. 19 is a section taken along line 19-19 of Fig. 17.
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Description of the Preferred Embodiment
[00311 The present invention relates to improvements in piston-type flush
valves such as those
illustrated in U.S. Patents 4,261,545 and 5,881,993, both owned by Sloan Valve
Company of
Franklin Park, Illinois. Additional reference should be made to U.S. Patent
6,299,127, also
owned by Sloan Valve Company, and illustrating a solenoid-operated flush
valve. The
invention will be described in connection with solenoid operation, but it is
also equally
adapted for manual handle operation as shown in the '545 and '993 patents.
When the flush
valve shown herein is arranged for manual operation the water passage between
the valve seat
and the hydraulic actuator will be closed.
[00321 As illustrated in Figs. 1 - 3, the flush valve includes a body 10
having an upper
interior thread 12 to which is threaded an outer cover 14. A decorative filler
ring 16 may
encircle the body 10 and outer cover 14 at the intersection of these two
parts. The body 10
has an inlet 18 which will be connected to a suitable source of supply water
and an outlet 20
which will be connected to either a toilet or a urinal.
[0033] Within the outer cover 14 there is an inner cover 22 which at its lower
end has an
outwardly extending flange 24. An undercut recess 26 (Fig. 2) is formed on the
underside of
the flange 24. The flange 24 rests upon an inwardly-directed ledge 28 of the
body 10. The
ledge has an internal axial surface 29. A seal 30 is positioned within the
recess 26 to form an
exterior seal for the flush valve body. The lower end 32 of the outer cover
14, after being
connected to the body at the threads 12, will bear against the top of the
flange 24 to lock the
inner cover 22 firmly in position on the flush valve body and within the outer
cover 14.
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[0034] Focusing on Fig. 2, the inner cover 22 has a small radius 34 at the
junction between the
flange 24 and the cover which matches an inner radius 36 on the bottom of the
end 32 of the
outer cover 14 so as to provide stress relief at the junction between these
two elements. Such
radii reduce stress on the flange which might otherwise crack or gouge this
portion of the inner
cover.
[0035] Positioned within the body 10 and the inner cover 22 is a piston 40
which is urged
toward a filtering main seat assembly 42. The main seat assembly is located
between the inlet
and outlet on a shoulder 44 of the valve body 10. The shoulder 44 has a radial
top land and a
cylindrical internal sealing wall 45. The piston 40 will be biased toward the
main seat assembly
42 by water within a pressure chamber 46. Water passes into the chamber 46
from the inlet 18
through a refill orifice 48 in the side wall of the piston 40. The refill
orifice is covered by an 0-
ring 50. Details of this structure are shown in the above-referenced 4,261,545
patent.
[0036] The interior of the piston 40 includes a seat 52 upon which rests a
seal 53 and a relief
valve 54. The relief valve is urged to this position by a spring 56 which
bottoms, at its lower
end, upon the relief valve 54, and at its upper end against a stop 58. The
stop 58 is threaded into
the top of the piston 40. The stop 58 has openings 60 through it which provide
fluid
communication between the refill orifice 48 and the pressure chamber 46.
[0037] The flush valve body 10 has an annulus 61 which defines an opening 62
in which an
actuator assembly 64 is mounted. The actuator assembly will effect movement of
the relief valve
54 in a manner described in the above-referenced patents. The actuator
assembly 64 includes a
solenoid 65 which can move a reciprocable plunger 72. The plunger normally
closes a passage
74 which extends through the otherwise closed end of a cup 78. The cup is held
in the opening
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62 by a sleeve 71 which has a radial extension that engages the closed end of
the cup. The sleeve
71 is clamped to the annulus 61 by a nut 73. The cup 78 defines a chamber 70
in which resides a
reciprocable, fluid-driven piston/rod assembly 66. A spring 68 biases the
piston/rod assembly 66
to the normal, retracted position shown in Fig. 1.
[0038] The sleeve 71 is sealed on its outer surface to the inner surface of
the annulus 61 but
the sleeve is not sealed on its inner surface to the cup 78. This permits
water to flow between the
sleeve and cup. Accordingly, the passage 74 in the end of the cup is in fluid
communication with
a hydraulic bypass 76 formed in the flush valve body. The bypass 76 receives
water flowing
from the inlet 18 through the filtering main seat assembly 42 as described
hereinafter. Under
normal conditions, water will leak between the exterior of the cup 78 and the
interior of the
sleeve 71 and be directly adjacent the passage 74. When the solenoid 65 is
activated it pulls its
plunger 72 away from passage 74. Water which has passed around the cup 78 will
flow through
the passage 74, causing the piston/rod assembly 66 to move against the force
of spring 68 and tilt
the relief valve 54. Tilting of the relief valve vents pressure within chamber
46 to the outlet 20.
Water pressure at the inlet 18 acting on the piston 40 is then no longer
counterbalanced by
pressure within chamber 46 so the inlet pressure causes the piston to rise off
of the main seat
assembly 42. This provides an uninterrupted fluid path between the inlet 18
and the outlet 20.
As water flows through the refill orifice 48, pressure in chamber 46 is
reestablished, which
gradually forces the piston back down on the main seat assembly, thereby
reclosing the valve.
The operation, as described, is more fully disclosed in the above-mentioned
U.S. patents owned
by Sloan Valve Company.
[0039] The inner cover 22 is more specifically shown in Figs. 4 - 8. The inner
cover includes
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the aforementioned outwardly-extending flange 24, beneath which are a
plurality of outwardly-
extending axial ribs 82 which extend from a peripheral wall 84. The ribs 82
engage the axial
surface 29 of the inwardly-directed ledge 28 to center the cover 22 within the
body 10. This in
turn centers the internal wall of the inner cover with the attendant sealing
benefit described
below.
[0040] As illustrated, the top 86 of the inner cover is domed, providing
additional strength to
resist the pressure within chamber 46. At the center of the dome 86 there is
an outwardly-
extending ring 88 which, as shown in Fig. 1, is in contact with the inside of
the outer cover 14.
There is a controlled clearance between the top of ring 88 and the inside
surface of the outer
cover to insure the maximum clamp load is directly applied to the seal 30 at
the inwardly-
directed ledge 28. As pressure increases to a sufficient amount, well above
100 psi, the inside
cover will expand to contact the outer cover which will then limit further
expansion.
[0041] The interior surface of the inner cover's top 86 has a downwardly-
extending annular
projection 90. This projection functions as a stop to limit upward movement of
the piston 40.
The stop 58 on the piston 40 will move upwardly during operation, but the
piston's upward
movement will be limited by the projection 90. The stroke of the piston
assists in determining
the duration of time during which the flush valve will provide a fluid
connection between the
inlet and the outlet. The ring 90 is reinforced by a plurality of radial ribs
92 shown particularly in
Figs. 5 and 8.
[0042] As best seen in Fig. 2 the piston 40 has a seal 94 which is carried by
the piston and
which bears against the inside wall 96 of the inner cover 22. This seal
establishes the pressure
chamber 46. The seal will move against the inside wall 96 as the piston moves
between the open
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and closed positions during flush valve operation.
[0043] One of the advantages of the inner cover as described and shown herein
is that it
isolates the outer cover from water contact, allowing the outer cover to be
made of a less
expensive material. Further, the ribs 82 improve alignment of the piston and
piston seal within
the flush valve body, thereby improving reliability of the valve. An
additional advantage is that
the seal between the valve body 10 and the cover may be easily renewed by
replacing the inner
cover.
[0044] It is preferred that the inner surface of the inner cover wall 96 have
a degree of texture.
The surface should not be so smooth that the lip seal of the piston will stick
and act erratically,
nor can it be so rough as to not provide for a complete seal between the
piston and the inner
cover. It is preferred that the finish on the inner cover have a surface
roughness in the range of
about 8 microinches to about 32 microinches.
[0045] Figs. 3 and 9 - 15 illustrate in detail the filtering main seat
assembly 42. The main seat
assembly is located between the inlet 18 and the outlet 20. Its principal
functions are to form a
semi-dynamic closing seal with the piston 40, to form a static seal with the
valve body, to guide
the piston during its operation, and to filter inlet water going into the
bypass 76 for hydraulic
assist with the actuator assembly. The main seat assembly 42 has two primary
components, a
main seat filter 98 and a sealing surface 100. Preferably the sealing surface
100 is molded
directly in place on the main seat filter 98. The sealing surface 100 is
engageable with a radial
surface 102 (Fig. 3) of the piston to form the semi-dynamic seal between the
piston 40 and the
main seat assembly 42. The piston also has a skirt 101 which centers the
piston in the main filter
seat.
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[0046] The main seat filter 98 is made of a material that is relatively rigid
compared to the
material of the sealing surfacel00. By way of example only, the main seat
filter may be made of
polypropylene which is 30% glass filled, while the sealing surface may be made
of a synthetic
elastomer, such as that sold by Advanced Elastomer Systems, under their
trademark
Santoprene . It will be realized that other suitable materials could be used.
[0047] The main seat filter 98 includes an annular ring portion 103 that
defines a central
opening 105. The main seat filter also has a lower, cylindrical portion 106
that extends
downwardly from the ring 103. An undercut notch 107 (Figs. 10 and 14) at the
bottom of the
cylindrical portion 106 receives an O-ring 104 (Fig. 3) which forms a static
seal with the internal
sealing wall 45 of the valve body shoulder 44 to eliminate leakage at this
point in the valve body.
The ring 103 has a plurality of v-notches or grooves 108 at its periphery
which are directly
adjacent the valve body portion 110 (Fig. 3). Together the grooves 108 and
body portion 110
define a plurality of small, filter-like passages whose collective total flow
area is larger than that
of the flow area defined by plunger 72 when activated and passage 74. As shown
herein, there
may be twenty-four such filtering grooves 108, although that exact number is
not essential to the
invention. The grooves 108 are positioned such that as the valve cycles, the
inrush of water will
wash away any large debris which may have accumulated in the grooves 108,
further reducing
the chances of the filter passages becoming blocked.
[0048] The main seat filter 98 also contains a plurality of landing pads 114
on a lower surface
116 of the ring 103. The pads function as a positive stop when installing the
seat onto the top
land of the valve body's shoulder 44. The pads further cooperate with the
portion 110 of the
valve body to define a flow passage about the periphery of the ring 103 of the
main seat filter 98.
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This flow passage connects the bypass 76 with the inlet supply water so that
the flush valve may
function correctly when the solenoid is operated.
[0049] It can be seen that the bypass 76 is downstream of the filter formed by
the ring 103 and
its grooves 108, but the bypass is upstream of the seal 104. Thus, inlet water
can go through the
filter and bypass 76 to get to the actuator assembly 64, but inlet water
cannot get around the main
seat assembly to the outlet 20, except when the valve is intentionally
activated.
[0050] It has been found advantageous to form the hydraulic bypass 76 by
casting it in place in
the valve body 10. This avoids the need for a secondary drilling operation
during manufacture of
the valve body. Furthermore, the bypass 76 should be arranged such that it
does not intersect
with the sealing wall 45 of the shoulder 44. By spacing the bypass from the
shoulder, well
outside of any sealing areas, the potential for damage to the main seat
assembly's seal ring 104
during installation is avoided. That is, because the bypass does not open in
the area of the
sealing wall 45, it cannot present any sharp edges or burrs that could
otherwise have the potential
to cut or damage the seal ring as the ring is moved past the bypass during
installation.
[0051] Figs. 9 - 15 illustrate further details of the main seat assembly 42.
The ring 103 and
sealing surface 100 have a geometry specifically tailored for this
application. The shape of the
sealing surface cooperates with that of the ring to provide the desired
performance. Specifically,
the upper surface of the ring 103 has an upstanding sill 118 about its
periphery. The grooves 108
are formed at the outer edge of the sill. The inner edge of the sill forms a
first axial wall 120.
The upper surface of the ring 103 further includes an upstanding rib 122 which
is generally
trapezoidal in cross section. That is, the top edge of the rib does not form a
sharp point but rather
is shaved off slightly to form a radial top edge. The rib has a second axial
wall 124. Together
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the first and second axial walls 120, 124 define a channel on top of the ring
103. A majority of
the sealing surface 100 is disposed within the channel. It is important that
the sealing surface be
bounded by the axial walls so that deformation of the sealing surface in a
radial direction is
limited.
[0052] The upper face of the sealing surface 100 includes a flat base 126 and
an upstanding,
arcuate crown 128. The crown is radially inward of the base. This profile
provides a higher
initial sealing stress by creating a line contact with the radial surface 102
on the piston. Thus, a
seal will be created at even the lowest of water pressures. This profile also
maintains a high
spring constant which limits compression of the sealing surface. As the water
pressure increases
the crown 128 will deform slightly which increases the sealing area on the
piston. But due to the
constraints in the geometry, the sealing area will never exceed a desired
limit. Even if the crown
were to flatten out completely, the contact area will be less than in prior
seals, thereby
maintaining the desired high seal stress, and the seat will be compressed less
than prior designs,
thereby allowing more consistent flushing. The compression of the sealing
surface is limited by
the mechanical stiffness of the elastomeric material and the area free to
expand. The area free to
expand is governed by the sealing surface's geometry and that of the ring 103.
Specifically, the
first and second axial walls 120, 124 define the channel in which the base 126
of the seal resides.
These walls limit the area of the sealing surface that is free to expand.
Another advantage of the
crown 128 and thickness of the base 126 is it counteracts the tendency of the
sealing surface
material to take a set after it has been under compression.
[0053] By way of example only and not by way of limitation, an acceptable
profile of the
sealing surface 100 has been made with the following approximate dimensions.
The diameter of
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the first axial wall 120 is about 1.43 inches. The height of the axial wall,
and thus the thickness
of the base 126, is about.045 inches. The diameter of the second axial wall
124 is about 1.06
inches while its height is .025 inches. The curvature of the crown 128 has a
radius of about .25
inches.
[0054] The base portion 126 of the sealing surface is interrupted by a set of
raised lockout lugs
130. As seen in Fig. 15, the lugs have a height greater than that of the crown
128. The height of
the lugs, together with the diameter of the base 126 on which they are
located, causes the lugs to
interfere with the seating of older pistons on the sealing surface. The older
style pistons have a
ring that will contact the lugs and prevent the such pistons from closing the
valve. Such older
style pistons are not to be used because they allow more water per flush than
permitted by current
codes. However, the lugs 130 will not interfere with the correctly-sized
piston 40. The radial
surface 102 of piston 40 has a diameter that allows it to fit inside of the
lugs 130 and in
engagement with the crown 128 of the sealing surface. The lugs 130 are molded
into the sealing
surface in such a manner that if one attempted to remove them it would very
likely lead to
destruction of the critical sealing surface. The lugs are shaped to create a
minimal flow
restriction when the piston is unseated. One of the lugs has an extension 132
that will partially
cover the bypass 76. This extension forces the water to be filtered by the v-
notches or grooves
108.
[00551 It will be noted that the structure described provides for precise
alignment of the
piston's dynamic seal 94 with the inside wall 96 of the inner cover. This
alignment is ultimately
dependent on the axial sealing wall 45 and the axial surface 29 of the ledge
28 being concentric.
These surfaces are carefully controlled during manufacture of the body to be
concentric. The
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lower cylindrical portion 106 of the main seat assembly 42 will then fit
inside the wall 45 and
assure alignment of the opening 105. The piston skirt 101 guides the piston in
the opening 105
to precisely locate the seal 94. Similarly, the centering ribs 82 on the cover
will fit inside the
axial surface of the ledge 28 to precisely locate the inside wall 96 of the
inner cover 22.
[0056] Figs. 16 - 19 illustrate the piston 40. The guide portion of the piston
is beneath the
radial surface 102. The guide portion includes the skirt 101 and a plurality
of equally-spaced
ribs 134. In this case there are five such ribs but their number could be
other than five. The
outer diameter of the ribs is such that the ribs fit just inside the opening
105 in the main seat
assembly 42 in guiding relation. As best seen in Fig. 18, the outside diameter
of the skirt 101
is somewhat less than that of the outer surface of the ribs. Accordingly, the
outer surface of
the skirt is spaced from the opening 105 to define a plurality of main water
flow passages when
the valve is open. These passages can be seen at 136 in Figs. 1, 18 and 19. By
way of
example, the outside diameter of the skirt may be about .886 inches while the
outside diameter
of the ribs define a circle whose diameter is about .980 inches. Accordingly,
the skirt occupies
approximately 90% of the space available through the opening of the valve
seat.
[0057] The ribs and skirt have an axial length sufficient to assure that
neither will ever be
withdrawn from the opening 105 of the main seat assembly. In other words, the
distance from
the bottom of the opening 105 to the bottom of the skirt and ribs is greater
than the available
travel of the piston. While in this embodiment the skirt extends axially to
the same extent as
the ribs, it could be otherwise. What is important is that the skirt and rib
lengths are such that
the available piston travel can withdraw neither the skirt nor the ribs from
the opening. This
contrasts with the piston in U.S. Patent 5,881,993 which has a shorter skirt
length so the skirt is
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withdrawn from the seat opening to provide a nearly completely open flow path
during the
initial phase of the valve opening cycle. While this is desirable when the
flush valve is used on
a water closet, it is not necessary in a flush valve used on a urinal. In the
present invention, the
flow path is constant and never larger than that presented by the relatively
narrow collective
passages 136. This regulates the flow rate to be uniform throughout the flush
cycle. The
relatively longer skirt also has the benefit of reducing turbulence during
flow through the
valve. This in turn prevents impingement of water on the relief valve stem,
which assures that
it will reseat properly and allow timely reestablishment of the pressure in
chamber 46.
[00581 While the preferred form of the invention has been shown and described
herein, it
should be realized that there may be many modifications, substitutions and
alterations thereto.
For example, if a conventional, manually-operated handle were installed
instead of the solenoid-
operated actuator 64, the bypass 76 may be plugged. Also, while the invention
has been
described in connection with use with low consumption urinal flushometers,
depending on the
volume of water required, it could be used on a water closet.
