Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
~ 1078704 :
The invention relates to a non-return valve, having a valve
housing, a valve seat, at least one closing part co-operating with the
latter ant mounted pivotably in said housing, and at least one closing spring
held stationarily therein ant comprising at least one pivotable operating
arm engaging with the closing part, in known non-return valves of this kind,
the closing spring is in the form of a torsion spring, the coils of which
are mounted upon the pivot axis of the closing part or parts, the ends of
the said coils extending at right angles to the axi~ thereof and forming
two legs, one or both of which engage with the said closing part or parts. -
The said spring thus exerts upon the said closing part or parts a closing
torque which increases with the opening angle. If the non-return valve ;
^ is to be fully opened, therefore, the load applied by the flow must be
relatively high and the flow volume must be large, but this is not always
the case under varying operating conditions. Non-return valves of this -
kind therefore operate at certain times in partly open positions, and this
is apt to cause chatter and flow noises. Flow losses are also relatively
large.
It is the purpose of the invention to provide a non-return valve
of the kind mentioned in the opening paragraph hereof in which the closing
spring exerts upon the closing part or parts a force which either increases
only slightly with the opening angle, or even decreases therewith, so
that a fully open non-return valve is possible even when the flow volume
is relatively small.
According to the invention there is provided a non-return
valve having a valve housing and a valve seat, at least one closing part
co-operating with the latter and mounted pivotably in the said housing,
and at least one closing spring held stationarily therein and comprising
at least one pivotable operating arm engaging with the said closing part,
~ characterized in that the closing spring is arranged in the inlet side
; 30 of the internal chamber of the valve housing; and in that a connecting
means is provided which connects the operating arm to the closing part to
; bias the closing part towards the valve seat, said connecting means
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comprising a slite connection that permits the point of engagement
between the closing part and the operating arm to move towards and : `~
away from the pivot of one of the operating arms ant the closing part,
during pivotal movement of the closing part.
This arrangement of the closing spring displaces the pivot
axis of the operating arm of the closing spring on the inlet side in
front of the
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pivot axis of the closing part. During the opening procedure~ this either ~ .
lengthens the effective lever arm on the spring side or shortens it on the
closing-part side, the said lever arm applying to the said closing part the ~ ~;
load produced by the closing spring. This change in the length of the lever
arm is superimposed over the unavoidable increase in the torque applied by the
closing spring as the valve opens, thus making it possible to obtain a closing
force which is actually smaller in the open position than in the closed posi-
tion of the valve.
Two embodiments of the invention are illustrated in the attached
drawings, wherein:
Figure 1 is a cross-section through a non-return valve according
to the invention having a closing part in the closed position;
Figure 2 shows the non-return valve according to Figure 1 in the
open position;
Figure 3 is a detail of the closing part of the non-return valve
according to Figure l;
Figure 4 shows a non-return valve according to the invention having
two closure parts, as seen from the inlet side and in part cross-section;
Figure 5 is a section through the non-return valve in Figure 4 along
the line 5 - 5;
Figure 6 is a detail of the non-return valve according to Figure 4,
as seen from the outlet side.
In the embodiment according to Figures 1 to 3, valve housing 1 has as
internal chamber 2 on the inlet side and an internal chamber 3 on the outlet
side. A closure part 4 is mounted pivotably upon an axis 5 located in internal
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chamber 3, the said closure part co-operating with a valve seat 6 (see Figure
2).
Arranged in internal chamber 2 in the inlet side of valve housing 1
` is a closing spring in the form of a torsion spring 7, the said spring having
coils 8, the ends of which extend to form two spring legs 9, 10 running at
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right angles to the axis of the spring coils. The short leg 9 bears against
valve housing 1, whereas the long leg 10 constitutes an operating arm engag- -
ing with closing part 4. To this end, the inlet face of the said closing
part is provided with a groove 11 which runs at right angles to pivot axis
;- 5 and has lateral undercuts 12, in which the free end of spring leg 10 is
engaged by means of lateral sliding arms 13 arranged at the free end there-
of. :
Torsion spring 7 is accommodated in a pocket-like recess 14 in the
wall of internal chamber 2, coils 8 of the said spring being thus recessed in
relation to the medium flowing through the non-return valve. The said coils
are mounted upon a removable pin 15 which is secured in the valve housing
parallel with pivot axis 5.
Since torsion spring 7 is located in the inlet side, its closing
action is applied to closing part 4 in tension.
As may be gathered from Figures 1 and 2, the point of engagement of ;~
torsion spring 10 with closing part 4, during the opening of the valve, moves
continuously towards pivot axis 5, since the pivot axis of spring leg 10 is
; displaced towards the inlet side in relation to the said pivot axis, the said
pivot axis of spring leg 10 coinciding with pin 15. The effective lever arm ~;
~;20 16, defined by the point at which the spring engages with the closing part,
therefore decreases accordingly. This effect is superimposed over the in-
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` crease in the closing force at end 13 of spring leg 10 occurring concurrently
with the opening of the valve. In spite of this increase in force, a reduc-
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tion is thus obtained in the closing force applied to closing part 4 by the
spring while the valve is opening.
,, The non-return valve illustrated in Figures 4 to 6 has two closing
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;~ parts 17, 18 arranged side by side and having adjacent pivot pins 19, 20
mounted in clips 21 in valve housing 1. Housing 1 is also provided with a
transverse web 22 acting as a valve seat for the adjacent edge areas of clos-
ing parts 17, 18. Associated with each of the latter, on the inlet side, are
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two torsion springs 23, 24, coils 25 of which are mounted on pins 27 located
in lateral recesses 26 on each side of transverse web 22. These pins are in
the form of cantilever studs secured to the valve housing by one end. Finally,
the inlet-side surfaces of closing parts 17, 18 have eyes 28 through which the
long legs 29 of torsion springs 23, 24 move axially, whereas the short legs 30
bear against transverse web 22.
In this design, eyes 28, and thus the points of engagement, on the
closing part side, of torsion springs 23, 24, slide on spring legs 29 and
move, while the valve is opening, towards the free ends of the said legs.
Thus the increasing torque applied by torsion springs 23, 24, while the valve
is opening, is transferred therefrom by a constantly lengthening effective
lever arm 31. This compensates for, or exceeds, the increase in the torque
applied by the said torsion springs, and this signifies a decrease in the
closing force applied to closing parts 17, 18 while the valve is opening.
The arrangement of torsion springs 23, 24 on the inlet side makes it
possible to locate the pivot axis of the closing parts in the immediate vicini-
ty of valve seat 6, and there is no longer any need for room for the springs
between the pivot axis and the valve seat. The freedom of movement required
for adequate opening of closing parts 17, 18 is provided by a separate pivot
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-; 20 axis or pin l9, 20 for each closing part 17, 18. This arrangement of the axes
~ close to the valve seat makes it possible to reduce the length of the housing
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. on the outlet side, thus making it possible to use a longer transverse web 22.
-~ The advantage of this is greater rigidity which allows a housing of short
;~ structural length to withstand heavy operating loads. Since they are located
in the neùtral-load zone of transverse web 22, recesses 26 provided for tor-
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sion springs 23, 24 in the said transverse web, do not affect the rigidity
,~ thereof.
~ In the pivot axis of the closing is arranged at a distance from the ,
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valve seat, as is the case with known mountings of the torsion springs on this
pivot axis, the outer edges, remote from the axis, of the two closing parts
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move, while the valve is opening, on an arc of a circle which initially runs
radially outwards and only later runs radially inwards.
This outwardly-directed component of movement makes it necessary to
provide correspondingly smaller closing partsJ as compared with the inside
; diameter of the closing bearing, on the outlet side, against the valve housing
(for instance a pipeline flange) in order to ensure access to the closing parts.
The location of pivot pins 19, 20 of closing parts 17, 18 close to
the valve seat, as in the embodiment shown in Figures 4 to 6, causes the outer
edges of the said closing parts to describe, as the valve opens, an arc 32
which is directed radially inwards right from the start. This makes it possi-
ble to use particularly large closing parts 17, 18, the freedom of which to
pivot is not obstructed by connecting part 33 on the outlet side. This advan-
tage is particularly significant in the case of non-return valves of large
widths.
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