Note: Descriptions are shown in the official language in which they were submitted.
1~358~
BACKGROUND OF THE INVENTION
This invention relates to an improvement of a ball valve.
In a conventional ball valve, a valve seat is pushed
to contact with a ball by a seat retainer which retains the
valve seat and is biased by an annular plate spring or a
plurality of coil springs (ten or scores number) to push the
valve seat to the ball, which are arranged between the seat
retainer and a valve body at a certain interval around the
periphery of the seat retainer, and one ends of which are
inserted in holes formed in the inner surface of the valve
body.
However, when the plate spring is used, it is difficult
to manu~acture them, and since the processing cost is high,
the manufacturing cost becomes very high especially when a
. high-grade or costly material is used. Further, different
sizes of such members are required depending on diameter sizes
of the ball valve. When the coil springs are used, it is
diEficult to manufacture the valve body, and a plurality of
coil springs are required. Further, their assembling operation
requires a lot oE time and trouble, and thus high cost.
SUMM~Y OF T~IE INVENTION
i It is an object of the present invention to provide
a ball valve free from the aforementioned disadvantages,
which is compact and simple in construction, and which is
capable of being manufactured at low cost.
According to the present iven-tion there is provided
a ball valve wherein a ball is pivotally mounted to a valve
body via a stem in contact with annular valve seats arranged
between the ball and the valve body, the improvement comprising
inclined coil springs, loops of each being inclined to the
same direction with respect to planes perpendicular to the
central axis of the coil spring, and each being elastically
; distorted without changing its entire length when it is com-
pressed from its opposite longitudinal sides in the direction
of the planes perpendicular to the central axis of the coil
spring, which are fitted in annular spaces between the valve
body and the annular valve seats in the distor-ted forms so
as to bias the annular valve seats onto the ball.
BRIEF DESCRIPTION OF DRAWI~GS
In order that the present invention may be better
understood a preferred embodiment thereof will be described
with reEerence to the accompanying drawings, in which:
~'ig. 1 is a central longitudinal cross-section of one
embodiment of a ball valve according to the present invention;
E'ig. 2 is an enlarged view of the part A of Fig. l; and
9 ~5~ 51
Fig. 3 is an extension view, seen along the line
III - III of Fig. 2.
DESCRIPTION OF THE PREFERRED EMBODIMENT
. ~
Referring to the drawings there is shown in Fig. l
a ball valve according to the present invention.
..,
A valve body l comprises a body cap la and a body
member lb which are coupled by boLts 2. A ball 3 pivotally
mounted to the body member lb via vertical stem 4.
A pair of seat retainers 5 are movably fitted in annular
concaves 6 cut on the inner surface o the valve body in
connection portions of left and right side parts of a valve
chamber lc and left and right fluid paths ld and le of the
valve body l.
i
Each seat retainer 5 is provided with an annular groove
7 in its inner side, facing the ball 3, in which a valve seat
8 is fitted. A thin cylinder member 5a having the same
coaxial diameter as the fluid paths ld and le is integrally
connected to the outer end of the seat retainer 5, and extends
outwards horizontally.
An inclined coil spring 9 comprises one coil spring
~ 5~
; whose loops are i.nclined to the same direction with respect
to planes perpendicular to the central axis of the coil spring,
in a form of saw's teeth, as clearly shown in Fig. 3. There-
fore, when it is compressed from its opposite longitudinal
sides in the direction of the planes perpendicular to the
central axis of the coil spring, it is elastically distorted
.,.
or flattened wihtout changing its entire length, and its bias
force depends on its length.
The inclined coil springs 9 having a proper length are
fitted in an annular space 10 of the annular concave 6 which
is surrounded by the valve body 1 and the seat retainer 5 so
as to bias the valve seat 3 onto the ball 3. Spacers 11 are
arranged between the ends of the inclined coil springs 9.
It is readily understood from the above description
that, since the seat retainers 5 are biased by the inclined
~i coil springs 9 described above, the desired bias force can
readily be obtained by varying the number of the inclined
coi]. springs 9 and the sum of their lengths.
Therefore, the same kincl of inclined coil spring can
be employed by properly cutting it for various ball valves
having different diameters and seat retainer to be biased
by the desired bias force depending on the different pressures
of the fluid to be flown and the different materi.als of the
; valve seat.
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Aceording to the present invention it is empirically
found that two kinds of inelined coil springs having two
different loop diameters fully cover the ball valves having
the diameters of 5 - 50 eentimeter.
Sinee the inclined coil spring has a very strong
elastic restitution foree, the inelined eoil spring can be
made by a finer coil material than a usual coil spring and
be manufactured easily at low eost even when the high-grade
material is used.
Further, in this embodiment, the proeessing of the
valve body is easy and the spaees oeeupied by the inelined
coil springs are small enough to make a compact valve body,
which means low manufaeturing eost.
Aeeording to the present invention one or a plurality
r'~ of inelined eoil springs compose an annular form without
using any spacer 11.
Although the present invention has been deseribed in
some cletai.l by way of illustration and example for purposes of
elarity oE understanding, it will, of eourse, be understood
that various ehanges and modifications may be made in the form,
details, and arrangements of the parts wlthout departing from
the seope of the invention as set forth in the following elaims.
