Note: Descriptions are shown in the official language in which they were submitted.
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A BALL VALVE
BACKGROUND OF THE INVENTION
Field of the Invention
The present invention relates to the field of ball
valves, more particularly to disposable plastic ball
valves.
Description of the Prior Art
Ball valves oF the known design are disclosed,
for example, in U.S. Patent No. 3,550,902 and Japanese
Unexamined Patent Publication (Kokai) No. 57-37160.
Such ball valves include tubular caps having connecting
portions for receiving ends of pipelines and abutting
against outer end walls of the valve housing. On the
external surfaces of the tubular caps, there are provided
outwardly extended flanges facing the outer end walls of
the valve housiny.
The ball valve further includes cap nuts having
inwardly extended flanges and internal threaded portions.
Thus, firm connection between the valve housing and the
tubular caps can be obtained when the internal threaded
portions of the cap nuts are threaded onto the external
threaded portions of the valve housing.
The ball valve disclosed in U.S. Patent No. 3,550,902,
however, has the following drawbacks:
(a) The union is merely inserted in the valve
body, so when the ball is in a closed position, the union
and the ball tend to disconnect from the valve housing
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due to upstream-side fluid pressure on the ball when the
downstream-side tubular cap is removed from the valve
housing, e.g., so as to replace the seating ring or
O-ring mounted in the union.
tb) The polytetrafluoroethylene seating rings
have no resiliency, so the contact surfaces of the
seating rings become worn by rotational friction of the
ball. Tight sealing between the ball and the seating
rings is therefore soon reduced. Thus, the seating rings
must be replaced after a comparatively short period of
valve use.
(c) The seating rings contact the annular
grooves formed in the valve body and the union at their
two sides, so there is a likelihood of the seating rings
being extruded into the flow passage when the fluid
pressure is applied to the seating rings through the
ball.
(d) After the ball valve is connected to the
pipelines, the pipelines are apt to deviate from the axis
Of the flow passage when excess heat or external force is
applied. This deviation of the pipelines causes damage
to the cap nuts and reduces the tight sealing performance
between the valve housing and the tubular caps, between
the valve body and the union, and between the union and
the ball.
In the construction of the ball valve disclosed in
Japanese Unexamined Patent Publication No. 57-37160, the
union is threaded into the valve body. Therefore, if the
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tubular caps and the cap nuts are removed from the valve
housing while the ball is in a closed position, the ball
and the union do not disconnect from the valve housing
due to the applied fluid pressure. As in the case of
U.S. Patent No. 3,550,902, however, the ball is discon-
nected from the valve housing when the union is removed
from the valve body so as to replace the seating rings.
In the case of this prior art, periodic replacement of
worn seating rings is required. In addition this type
of the ball valve has the same drawbacks (c) and (d) as
the former ball valve.
SUMMARY OF THE INVENTION
A primary object of the present invention is to
provide an improved ball valve which can substantially
eliminate the aforementioned conventional drawbacks.
Another object of the present invention is to
provide a ball valve wherein the ball and the union do
not disconnect from the valve housing under pressure of
fluid.
A further object of the present invention is to
provide a ball valve wherein the seating rings do not
extrude into the flow passage under pressure of fluid, so
as to obtain excellent sealing performance over extended
valve use.
According to the present invention, there is provided
a ball valve comprising a valve housing having a flow
passage therethrough; a spherical ball mounted in the
valve housing for movement between an open position and a
closed position; tubular caps having connecting means for
receiving ends of pipelines and abutting against outer end
walls of the valve housing, the tubular caps provided with
externally extended annular flanges; and cap nuts provided with
internally extended annular flanges cooperating with the exter-
nally extended annular flanges of the tubular caps ana internal
threads cooperating with the external threads of the valve hous-
ing. This allows firm connection between the valve housing and
the tubular caps when the internal threads of the cap nuts are
threaded onto the external threads of the valve housing. The
valve housing is provided with a tubular valve body terminating
at one end with a cylindrical through hole and at the other end
with a larger cylindrical through hole, a tubular union adhered
inside the larger cylindrical hole of the valve body and having
a cylindrical through hole, and a valve chamber formed between
the valve body and the union. The valve chamber is intended to
rotatably receive the ball having the cylindrical through hole.
on the opposite surfaces of the valve body and the union fac-
ing the ball, annular grooves of a rectangular cross-section
are formed. The rectangular annular grooves are concaved into
the respective valve body or union from the contact surfaces to
the ball in the axial direction thereof. Within the annular
grooves are fitted annular seating rings having conical inner
surfaces and made o~ hard polytetrafluoroethylene backed by
annular resilient rings made of elastic rubber so as to be in
tight contact with the ball.
In a ball valve according to another aspect of the present
invention, outer end walls of the valve housing are ~ormed
substantially in the shape of convex spherical surfaces having
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radii centered on the axis of the flow passage. Inner end
walls of the flanges of the tubulax caps cooperating
with the outer end walls of the valve housing are formed
complementary to the convex spherical surfaces of the
outer end walls. Inner end walls of the flanges of the
cap nuts are formed substantially in the shape of concave
spherical surfaces having radii centered on the axis of
the flow passage. Outer end walls of the flanges of the
tubular caps are formed complementary to the concave
spherical surfaces of the inner end walls.
BRIEF DESCRIPTION OF THE D~AWINGS
Further characteristics and advantages of the
present invention will become apparent from the Eollowing
description made with reference to the attached drawings,
wherein:
Fig. 1 is a partial cross-sectional view of an
elevation of an embodiment of a ball valve according to
the present invention;
Fig. 2 is a view similar to Fig. 1 but showing
an alternative embodiment of the present invention.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Referring now to the drawings, preferred embodiments
of a ball valve made by, for example, polyvinyl chloride
are illustrated.
In Fig. 1, reference numeral 10 indicates a valve
housing including a valve body 11 and a union 12.
The valve body 11 is provided with a cylindrical
through hole at one end and a larger diameter cylindrical
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through hole at the other end. The holes coincide and
communicate with each other along the axis of the valve
housing 10.
The union 12 has a cylindrical through hole and
tightly fits inside the larger diameter hole of the valve
body 11. The external surface of the union 12 is adhered
with the internal surface of the larger hole by means of
any suitable adhesive agent so as to form a valve chamber
centrally located in the valve housing 10.
Positioned within the valve chamber is a rotatable
spherical ball 13 having a cylindrical through hole
coinciding with the holes of the valve housing 10. The
ball 13 is supported for rotation on two new and improved
sets of annular seating rings and back~up rings, which
will be described in detail hereinafter.
The ball is intended to be turned by means of a valve
stem 13A and a lever 14 connected thereto. -Lt should be
noted that the through holes provided in one end of the
valve body 11, in the union 12, and in the ball 13
construct a flow passage of the ball valve.
On the surfaces of the valve body 11 and the
union 12 facing the ball 13 and adjacent to the flow
passage, there are formed two annular grooves llD and 12B
of rectangular cross-sections. The annular grooves llD
and 12B are disposed in parallel with respect to the
plane normal to the valve housing axis.
Within the annular grooves llD and 12B, annular
seating rings 15 and 16 made of hard polytetrafluoro-
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ethylene backed by annular resilient rings 17 and 18 madeof elastic natural or synthetic rubber are fitted. The
surfaces of the seating rings 15 and 16 abutting the
ball 13 are formed conically, so as to provide tight
sealing between the seating rings 15 and 16 and the
ball 13. The resilient rings 17 and 18 are formed
rectangularly in cross-section and function to urge the
seating rings 15 and 16 against the ball 13 with proper
pressure.
When the ball 13 is turned into its closed position
by operating the lever 14, the fluid pressure upstream of
the flow passage is applied to the ball 13. In turn, the
fluid pressure may be transmitted to the resilient rings
17 and 18 through the seating rings 15 and 16. Since the
seating rin~s 15 and 16 and the resilient rings 17 and 18
are fitted within the rectangular grooves llD and 12B,
the fluid pressure applied to the seating rings 15 and 16
from the ball 13 is completely transmitted to the
resilient rings 17 and 18 and not toward the flow
passage. Also, since the sealing rings 15 and 16 contact
the inside walls of the rectangular grooves llD and 12B,
at their three sides, there is no likelihood of the
sealing rings 15 and 16 being extruded into the flow
passage. In addition, since the resilient rings 17
and 18 per se have elasticity, they resist the applied
pressure and thrust back the seating rings 15 and 16
toward the ball 13. Consequently, tight contact between
the seating rings 15 and 16 and the ball 13 can be
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achieved. Even if the polytetrafluoroethylene layer of
the seating rings 15 and 16 is considerably reduced in
thcikness by frictional rotation of the ball 13, the
sealing performance of the sealing rings is still
maintained by means of the elasticity of the resilient
rings 17 and 18.
In addition, the resilient rings 17 and 18 function
to align the ball 13. When the ball 13 is pressed by
fluid pressure and is deviated from its original position,
i.e., from the position on the axis of the flow passage,
the resilient rings 17 and 18 will thrust back the
ball 13 through the seating rings 15 and 16 to bring it
back to its correct original position. Thus, the ball 13
can be continuously maintained on the axis of the flow
passage.
The end portion of the valve body 11 is provided with
an outer end wall llA abutted to an inner end wall l9A of
a tubular cap 19. The end portion of the union 12 is
provided with an outer end wall 12A abutted to an inner
end wall 20A of a tubular cap 20. The tubular cap 19 is
the upstream cap, and the tubular cap 20 is the downstream
cap. These tubular caps 19 and 20 include through holes
of the same diameter as that of the flow passage of the
valve housing 10 and have receiving portions for attaching
ends of pipelines (not shown) to the ball valve. O-rings
27 and 28 are disposed between the valve body 11 and the
tubular cap 19 and between the union 12 and the tubular
cap 20, respectively, to prevent fluid leakage from the
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ball valve.
Outer end portions of the valve body 11 are provided
with external threads llB and llC at their external
peripheral surfaces for cooperation with internal threads
23A and 24A on cap nuts 23 and 24. The cap nuts 23
and 24 have inwardly extended annular flanges 25 and 26
whlch cooperate with externally extended annular flanges
21 and 22 on the tubular caps 19 and 20. Thus, firm
connection between the valve housing 10 and the tubular
caps 19 and 20 can be obtained when the internally
threaded portions of the cap nuts 23 and 24 are threaded
onto the externally threaded portions of the valve
body 11 and when the flanges 25 and 26 come into contact
with the flanges 21 and 22.
As described above, because the union 12 and the
valve body 11 are adhered to each other by an adhesive
agent, even if the downstream tubular cap 20 is removed
during the closed condition oE the ball valve, the
ball 13 and the union 12 will not disconnect from the
valve body 11 by fluid pressure. Also, it can readily be
understood that repalr and replacement of the valve
housing 10 or replacement of the O-rings 27 and 28 can be
easily effected by loosening the cap nuts 23 and 24 and
removing them from the valve housing 10.
Figure 2 shows an alternative embodiment of the
present invention relating to the connective construction
between the valve body and the tubular caps.
The ball valve 110 in Fig. 2 includes many similar
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elements as in the ball valve 10 in Fig. 1. These
elements are designated with the same numerals prefixed
by the numeral "1" and differ from their counterparts
only to the extent mentioned.
In the alternative embodiment, outer end walls lllA
and 112A of a valve body 111 and a ùnion 112 are formed
substantially in the shape of convex spherical surfaces
having radii centered on the axis of the flow passage.
Associated inner end walls ll9A and 120A of the tubular
10 caps 119 and 120 are formed in the shape of concave
spherical surfaces, i.e., the shape of inner end walls
ll9A and 120A complement the outer end walls lllA
and 112A. It should be noted that the above radius
centers may be positioned away from the axis of the flow
passage,
Inner end walls 125A and 126A of flange portions 125
and 126 of cap nuts 123 and 124 are formed in the shape
of concave spherical surfaces having radii centered on
the axis of the flow passage. Associated outer end walls
121A and 122A of flange portions 121 and 122 of the
tubular caps 119 and 120 are formed in the shape of
complementary convex spherical surfaces.
It should be noted that the inner end walls 125A
and 126A can be formed in the flat planes normal to
the axis of the flow passage. However, as mentioned
previously, if such inner end walls 125A and 126A are
formed in the shape of concave spherical surfaces, then
the complementary convex outer end walls 121A and 122A of
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the flange portions will cooperate to make a tighter
connection between the cap nuts 123 and 124 and the
tubular caps 119 and 120.
Outer end walls lllA and 112A of the valve body 111
and the union 112 are preferably formed in the shape of
spherical surfaces with large radii. Preferably, they
are formed with radii 4 to 20 times the diameter D of the
flow passage. More preferably, they are formed with
radii 10 to 20 times the diameter D.
- 10 After the ball valve is firmly connected to the
pipelines, the downstream-side pipeline is apt to deviate
from the axis of the flow passage when excess heat or
external force is applied by any circumferential
conditions. As a result, the tubular cap 120 will
deviate together with the pipeline.
In such a case, the tubular cap 120 can be slidably
displaced along the spherical outer end wall 112A of the
union 112, i.e., the cap nut 124 and the union 112 will
not receive excess force. Accordingly the sealing
performance between the cap nut 12~ and the union 112
will not be spoiled.
The above description is also applicable to the
upstream-side pipeline and the tubular cap 119.
The invention has been described in detail with
reference to preferred embodiments thereof, but it will
be understood that reasonable variations and modifications
are possible without departing from the spirit and scope
of the present invention.
