U.S. patent number 3,757,866 [Application Number 05/196,641] was granted by the patent office on 1973-09-11 for on-off sprinkler.
This patent grant is currently assigned to Grinnell Corporation. Invention is credited to James William Mears, William James O'Brien.
United States Patent |
3,757,866 |
Mears , et al. |
September 11, 1973 |
**Please see images for:
( Certificate of Correction ) ** |
ON-OFF SPRINKLER
Abstract
An improved sprinkler for a fire protection sprinkler system in
which the sprinkler opens to discharge water at one temperature and
closes to stop the flow of water at a lower temperature. A pilot
valve is actuated by a bimetal disc which also resiliently biases
the pilot valve in a closed position. The bimetal disc has a snap
action resulting in better control of the "on" and "off"
temperatures of the sprinkler. A thermal delay for closing is
obtained by the hysteresis which is designed into the bimetal
disc.
Inventors: |
Mears; James William
(Providence, RI), O'Brien; William James (Providence,
RI) |
Assignee: |
Grinnell Corporation
(Providence, RI)
|
Family
ID: |
22726227 |
Appl.
No.: |
05/196,641 |
Filed: |
November 8, 1971 |
Current U.S.
Class: |
169/37 |
Current CPC
Class: |
A62C
37/08 (20130101); F16K 17/38 (20130101) |
Current International
Class: |
A62C
37/08 (20060101); F16K 17/38 (20060101); F16K
17/36 (20060101); A62c 037/08 () |
Field of
Search: |
;169/1,2,19,37
;137/457 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: King; Lloyd L.
Claims
We claim:
1. A water sprinkler device for a fire protection system coupled to
a pressurized fluid supply line; comprising in combination:
a sprinkler body having an annular inlet portion adapted for
coupling to said fluid supply line;
means providing an inner wall for dividing said sprinkler body into
a first bifurcation, having an outlet portion that defines a main
fluid flow passageway between said inlet portion and said outlet
portion, and a second bifurcation that defines a control
chamber;
a deflector mounted adjacent said outlet portion to deflect fluid
flow therethrough;
means providing a valve seating surface abutting said inlet portion
at the junction of said bifurcations;
a main valve disposed in a direction downstream from said seating
surface and having a valve seat mounted in opposed relation to said
seating surface so as to oppose fluid pressure from said inlet
portion that tends to cause said valve seat to separate from said
seating surface to open said valve,
said main valve being slideable into said control chamber for
controlling fluid flow through said main passageway while
maintaining said control chamber blocked to fluid flow from said
outlet portion,
an aperture formed substantially centrally in said main valve to
define a control passageway that couples fluid from said inlet
portion to said control chamber;
said main valve exhibiting a first surface area disposed toward
said control chamber that is greater than a second surface area
disposed toward said inlet portion to provide a greater main valve
closing pressure than opening pressure,
means providing an outlet port from said control chamber to release
fluid pressure therefrom to open said main valve,
pilot valve means having a valve member mounted to control fluid
flow through said outlet port and including a bimetallic disc
centrally connected to said valve member, and
means for securing the peripheral edges of said bimetallic disc
against movement relative to said sprinkler body so as to flex said
disc in a manner to resiliently bias said valve member to close
said outlet port, said disc responding to temperature rise to snap
to an opposite flexure to open said outlet port to release fluid
from said control chamber to open said main valve.
2. The combination in accordance with claim 4 wherein said
bimetallic disc exhibits a hysteresis effect wherein said disc
flexes in one direction to open said pilot valve means upon the
occurrence of a first predetermined temperature but flexes in the
reverse direction to close said pilot valve means upon the
occurrence of a second temperature lower than said first
predetermined temperature.
Description
BRIEF SUMMARY OF THE INVENTION
Conventional sprinklers for fire sprinkler systems are single
operation devices wherein a heat responsive member releases a plug
which is positioned to prevent the flow of water from the
sprinkler. When the plug is released, water flows against a
deflector which disperses the water in a desired pattern. Such a
sprinkler must be replaced after a fire and the entire sprinkler
system must be shut off to replace the sprinkler.
Many attempts have been made to produce a sprinkler which would
shut itself off after a fire is extinguished. Such a sprinkler
would conserve water because the flow of water is shut off, and it
would be ready to operate immediately if the fire should start up
again. In one design a fluid balanced piston valve is utilized to
control flow of the extinguishing fluid from the sprinkler. A pilot
valve controls the fluid balance and, thus, the position of the
piston valve in either an open or a closed position. The pilot
valve in turn is positioned by a leaf bimetal member which is
responsive to atmospheric temperature. (See U.S. Pat. No.
917,292.)
The present invention provides an improved pilot valve arrangement
in which a bimetal snap disc is used to position the pilot valve.
The bimetal disc is positioned to load or resiliently bias the
pilot valve toward a closed position. A hysteresis is built into
the disc and is utilized to move the pilot valve to its closed
position at a temperature lower than that at which the pilot valve
is moved to an open position. With this built-in thermal delay, the
sprinkler is not shut off until the surrounding temperature is low
enough to assure that the fire is out.
An object of the present invention is to provide an improved on-off
sprinkler having a fluid balanced main valve and a pilot valve for
controlling the fluid balance on the main valve, in which the
operating temperature of the sprinkler is controlled to close
tolerances for both an "on" operation and an "off" operation.
Another object is to provide an improved on-off sprinkler in which
the pilot valve is moved with a snap action.
Another object is to provide an improved on-off sprinkler in which
the pilot valve is resiliently biased in a closed position at
temperatures below a predetermined operating temperature by a
bimetal disc.
Another object is to provide an improved on-off sprinkler which
opens at one predetermined temperature and closes at a second,
lower predetermined temperature.
Other advantages and features of the invention will be apparent
from the following description and accompanying drawings.
BRIEF DESCRIPTION OF DRAWINGS
FIG. 1 is a sectional, front view of an on-off sprinkler embodying
the present invention, in which the sprinkler is shown in an "off"
position;
FIG. 2 is a sectional, front view of the sprinkler shown in FIG. 1,
in which the sprinkler is shown in an "on" position; and
FIG. 3 is a partially sectioned right side view of the sprinkler
shown in FIG. 2.
Referring first to FIG. 1, the improved sprinkler embodying the
present invention is shown in a pendent position. The sprinkler has
a body 10 defining a circular, threaded opening 12, a flow passage
14, and an outlet 16, spaced from the opening 12. The body 10 is
preferably formed by a casting of a suitable material such as
bronze. An inner wall 18 cooperates with an inner wall 22 and the
outer wall of the body 10 to define a cylindrical chamber 20, the
axis of which passes through the center of the threaded opening 12.
The threaded opening 12 has a diameter which is at least as great
as the diameter of the cylindrical chamber 20. The second inner
wall 22, which is positioned at the lower end of the chamber 20,
cooperates with a lower wall 24 of the body 10 to define a threaded
opening 26 and a chamber 28. The chamber 28 is aligned with a
passage 30 and communicates through the passage 30 with the chamber
20 and the chamber 28 communicates with the flow passage 14 through
a passage 32 in the wall 18. The cylindrical surface 21 of the
chamber 20 is finished smooth, and a smooth seating surface is
formed on the area 31 of the wall 18 surrounding the entrance to
the passage 32.
An inlet member 34 has an externally threaded end 35 which mates
with the threaded opening 12 to secure the inlet member 34 in the
opening 12 of the body 10. A second externally threaded end 36 is
of a size which is suitable for connecting the sprinkler to a
sprinkler piping system.
The inlet member 34 further has a cylindrical passage 38 which
provides an axial passage for fluid through the inlet member to the
flow passage 14. The diameter of the flow passage 38 is less than
the diameter of the chamber 20. An annular surface 39 at the inner
end of the inlet member 34 is smooth and function as a seating
surface, as will be explained hereinafter.
A piston assembly 40 is received in the chamber 20, and closes the
upper end of the chamber 20. The piston assembly 40 comprises a
piston 42 having a first cylindrical portion 44 and a second,
smaller cylindrical portion 46. An axial bore 48 through the second
cylindrical portion 46 and axial counterbores 50 and 52 in the
first cylindrical portion 44 provides a passage axially through the
piston 42.
The first cylindrical portion 44 of the piston 42 has a diameter
which is sized to be slideably received in the passage 20 of the
inlet member 34. The second cylindrical portion 46 of the piston 42
has a diameter which is sized to be slideably received in the
cylindrical chamber 38. In this manner, the piston 42 is mounted
for axial movement toward and away from the inlet member 34. The
second cylindrical portion is provided with ports 53 positioned to
permit a fluid to pass from the axial passage 38 to the flow
passage 14 only when the piston 42 is positioned in its lower
postion of travel.
An O-ring 54 in a groove 56 in the outer surface of the first
cylindrical portion 46 prevents fluid flow through the annular
space between the wall 21 and the first cylindrical portion 44.
An annular lip 70 projects from the surface which connects the
outer surface of the first and second cylindrical portion 46 to
form, with the cylindrical portion 46, an annular groove 72. This
groove 72 receives an O-ring 74 which engages and seats against the
surface 39 of the inlet member 34 when the piston 42 is moved
axially toward the inlet member to provide a fluid seal.
A restriction member 82 and a strainer 84 are secured in the
counterbore 50 of the piston 42 by a retaining ring 80. The
restriction member 82 has an orifice 86 to control fluid flow from
the inlet port to the chamber 20. The strainer 84 will prevent the
obstruction of the orifice 86 by foreign materials which may enter
the sprinkler from the sprinkler system to which the sprinkler is
connected. The strainer 84 has a domed portion to provide an
increased area and flow passages through the strainer. Both
strainer 84 and the restriction member 82 are formed of
non-corrosive materials such as brass or bronze.
A coil spring 90 is positioned between the retaining ring 80 and
the inner wall 22 to provide a resilient bias to the piston 40
toward the inlet member 34. The lower end of the spring 90 fits
into a recess 92 in the wall 22 to keep the spring in position.
It will be noted that the area of the piston assembly 40, which can
be acted on by fluid pressures in the passage 38, is considerably
less than the area of the piston assembly which can be acted on by
fluid pressures in the chamber 20, so that when the inlet fluid
pressure and the fluid pressure in the chamber 20 are equal, the
balance of fluid pressures will hold the piston 42 in its closed
position.
In accordance with the present invention, an improved pilot valve
assembly 100 is provided for controlling fluid flow from the
chamber 20, the passage 30, the chamber 28, and through the passage
32 to the flow passage 14. The pilot valve assembly 100 comprises a
retainer member 102 having an externally threaded cylindrical
portion 102 which is of a suitable size for engaging the threads of
the threaded opening 26 of the body 10. The retainer member 102 has
a radial flange portion 106 which is positioned a short distance
away from the body 10 when the retainer member 102 is threaded into
the opening 26. A bore 108 extends axially through the retainer
member 102.
A pilot valve 110 having a cylindrical portion 112 fits loosely for
axial movement in the bore 108 and in the cavity 28. An O-ring 116
fits in a recess 118 in the outer surface of the cylindrical
portion 112 to provide a fluid seal between the cylindrical portion
112 and the surface of the bore 108.
The valve 110 has an axial length which permits the inner end 120
to touch the seat surface 31 surrounding the passage 32. An O-ring
122 in an annular groove 124 in the surface of the end 120 provides
a fluid seal with the seat surface 31 when the valve 110 is urged
axially thereof toward the seat surface 31.
A bimetal disc 126 is centrally connected to the outer end of the
valve 110 by a drive screw 128 which passes through a central
opening in the disc 126 and into a drilled hole in the outer end of
the valve 110. The edges of the disc 126 are secured to the radial
flange 106 by drive screws 132. Preferably, the area of contact of
the drive screws 132 with the bimetal disc is held to a minimum so
that heat flow from the bimetal disc 126 to the flange 106 is at a
minimum. A thermal insulator (not shown) could be installed between
the contact points of the disc with the drive screws 132, if
desired.
A conventional deflector 130 is spaced from the outlet 16 of the
flow passage 14 and perpendicular to the projected axis of the flow
passage 14 by a yoke 131 which is generally U-shaped.
The free ends of the yoke 131 are serrated and secured in openings
134 which are drilled therefor in the body 10 by swaging, as at
136, the body 10 against the serrations, as seen in FIG. 3. The
deflector 130 is secured to the yoke 131 by a rivet 138.
In accordance with the present invention, the bimetal disc 126 is
cupped and is designed to move with a snap action toward a reverse
cup shape at one temperature, for example 185.degree. F, and when
in the reversed shape, to return to its original shape at a second,
lower temperature, for example 100.degree. F. Further, the bimetal
disc 126 is positioned with its concave surface facing the pilot
valve 110 and is urged against the valve 110 to resiliently bias
the valve 110 toward its closed position.
To compensate for the stress loading of the bimetal disc 126, a
temperature rating is selected for the bimetal disc 126 which is
higher than the desired operating temperature. In order to position
the pilot valve assembly 100 in the body 10, to provide a resilient
bias on the valve 110 and to obtain operation of the pilot valve at
a desired temperature, the assembly 100 and the body 10 are put in
a heated environment at the desired operating temperature of the
sprinkler. The retainer member 102 is threaded into the opening 26
and tightened until the O-ring 122 is pressed against the seating
surface 31 with sufficient pressure at the desired operating
temperature of the sprinkler to cause the bimetal disc 126 to snap
to the position to open the pilot valve. The pilot valve assembly
is now installed in its proper position with the desired bias
provided by the bimetal disc 126.
An anaerobic plastic, such as "Loctite" No. 70, is applied to the
threads of the retainer member 70 prior to its being put in the
heated oven for installation. This anaerobic plastic will harden to
lock the threads in this position.
It will be recognized that the pilot valve 110 can be resiliently
biased toward its closed position by a separate spring and that it
is not necessary to obtain the bias from the bimetal disc 126.
In operation, the sprinkler is installed in a sprinkler system in a
pendent position. When the water is turned on, water flows into the
passage 38, the axial bore 48, through the strainer 84 and the
orifice 86 in the restriction member 82, to fill the chambers 20
and 28. The pilot valve 110 is held in a closed position by the
resilient force of the bimetal disc 126 so that no water discharges
through the passage 32. When the chambers 20 and 28 have filled
with water, equal fluid pressure is established above and below the
piston 42.
Because the area of the piston assembly 40 which is exposed to
fluid pressure in the chamber 20 is greater and produces a greater
force on the assembly 40 tending to move the piston assembly
axially toward the inlet member 34 than the area and the force
which is produced by the fluid tending to move the piston assembly
40 axially away from the inlet member 34, the O-ring 74 is pressed
tightly against the surface 39 to close the sprinkler.
In the event of a fire, the temperature surrounding the bimetal
disc 126 will rise. As the bimetal disc 126 reaches its operating
temperature, the disc snaps to a reverse cup shape, moving the
pilot valve 110 with it and moving the O-ring 122 off its seat 31.
Immediately water discharges from the chamber 28, through the
passage 32, thereby lowering the pressure sufficiently in the
chamber 20 so that its force against the area of the piston
assembly 40 becomes less than the force of fluid in the inlet
member. Restriction member 82 prevents fluid pressure from building
up in chamber 20. At a point, the fluid pressure against the top of
the piston assembly is sufficient to overcome the force of the
spring 90 causing piston assembly 40 to move axially downward to an
open position, as shown in FIG. 2.
With the piston assembly in this position water flows through ports
53, and along the flow passage 14 to discharge against the
deflector 130. As the deflector is below the bimetal disc 126 with
the sprinkler in a pendent position, the discharging water will not
cool the bimetal disc 126 as long as the fire continues to
burn.
After the fire is extinguished, the bimetal disc 126 cools and,
upon reaching its lower operating temperature, snaps to its
original position to move the pilot valve 110 to a position to
close the passage 32. As the chambers 28 and 20 fill with water,
the pressure in the chamber 20 increases until it produces a force
which moves the piston assembly 40 axially toward the inlet member
34 to stop further flow through the sprinkler.
The invention is not intended to be limited to the particular
embodiments thereof illustrated and described above, but only by
the following claims and their equivalents.
* * * * *