Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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The present invention relates to a non-return valve
for shutting off lines, for example, the suction line of com-
pressors, comprising a valve seat disposed in a valve housing.
The valve seat is closable by a flap pivotably supported about
a swivel axis, the flap being biassed by a biassing weight in
the closing direction.
A non-return valve of this construction is disclosed
in British Patent 983 779. In the valve the pivotably sup-
ported flap has a protruberance on its side remote from the
valve seat, said protruberance forming a biassing weight for
returning the flap into the closing position. Because of this
protruberance the flap is unwieldy and heavy so that it reacts
slowly during the opening and closing motions. Furthermore,
the protruberance requires additional space inside the valve
housing.
A further non-return valve of this construc-tion is
described in US Patent No. 1 507 001. The swivel axis of the
valve flap, which is a cylindrical shaft, is disposed outside
the housing and is provided with an arm which is non-
rotationally mounted on the swivel axis and carries a biassingweight. The arm with the biassing weight is so mounted on the
swivel axis that it extends approximately horizontally when
the flap is closed or shortly before the closing position
thereof. However, when the flap is open the arm extends
almost vertically. Therefore, the closing force in or shortly
before the closing position of the flap is at a maximum but in
the open position it is relatively small. Like the construc-
tion of the non-return valve of the British Patent, this non-
return valve also has the disadvantage that when the flow in
the valve housing is revqrsed and the non-return valve should
close quickly, the closing motion is relatively slow since the
counterweight must also accelerate together with the flap.
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Because of both the large mass and the torque exerted by the
biassing weight in the closlng direction, the valve flap
impinges relatively hard on the valve seat. Thus the valve
flap rebounds on impinging and once more temporarily releasing
the valve seat.
The present invention improves tha non-return valves
of the aforesaid construction such that the aforesaid disad-
vantages of the conventional non-return valves are avoided.
In particular a rapid and unobstructed closing motion is made
possible and the disadvantageous rebound of the flap from the
valve seat is avoided.
According to the present invention there is provided
a non-return valve for shutting off a line, such as the
suction line of a compressor, comprising a valve seat disposed
in a valve housing, said valve being closed by a flap
pivotably supported on a swivel axis, said flap being biassed
in the closing direction by a biassing weight pivotably
supported independently of the flap and provided with a
follower detent which freely strikes a counterdetent in the
flap in the direction of the closing motioin thereof.
Thus in accordance with the present invention the
biassing weiyht is pivotably supported independently of the
flap and is provided with a follower detent which freely
strikes a counterdentent of the flap in the direction of the
closing motion thereof. In this construction the biassing
weight rests against the flap when the non-return valve is
closed and exerts the maximum closing force. The opening
motion of the flap is similar to that in the conventional non-
return valves and the passage cross section can be completely
cleared. However, as soon as the flow through the non-return
valve ceases the flap is àccelerated independently of the
biassing weight and is rapidly pressed into abutment with the
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valve seat by the reverse flow of the medium in the valve.
The flap thus leads the biassing weight, which follows more
slowly due to its larger mass until its detent impinges on the
counterdetent of the flap. Subsequently the biassing weight
securely holds the flap on the valve seat even when the flow
of medium stops. A disadvantageous temporary raising of the
flap after the first impingement on the valve seat is thus
avoided.
In a further embodiment of the non-return valve of
the present invention at least one of the interacting detents
of the biassing weight and of the flap is provided with a
damping layer. Not only is thus the impingement of the two
detents on each other damped but upon impinging on the flap
the biassing weight is also prevented from rebounding in the
direction of the opening motion thereof.
Furthermore, according to the present invention a
limit stop for the biassing weight in the direction of the
opening motion of the flap can be provided on the valve hous-
ing. The limit stop preferably has a damping layer. Thus,
when the non-return valve is open, the position of the
biassing weight and of the corresponding valve flap is
precisely defined and hard impingement of the biassing weight
in the end position are avoided by the damping layer. secause
of the independently pivotable support of flap and counter-
weight it is also possible to provide separate limit stop for
the flap and to subsequently intercept the counterweight at a
further detent.
The flap and the biassing weight can be disposed on
the same swivel axis (shaft) in the valve housing. In a
preferred embodiment a protruberance serving as a counter-
detent is secured to the ~lap underside facing away from the
valve seat as are the U-shaped arms extending therefrom and
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carrying at their ends the swivel supports of the flap between
which the biassing weight with a borehole for its support is
disposed, the detent pro~ecting from the underside thereof.
This structure is relatively simple and assures an exact
control of the flap and of the biassing weight in the opening
motion as well as in the swivel motion of the flap and of the
biassing weight relative to each other.
The present invention will be further illustrated by
way of the accompanying drawings, in which:-
Figure 1 is an axial cross section of a non-return
valve in accordance with one embodiment of the present
invention; and
Figure 2 is a view from below of the flap and
biassing weight in the non-return valve of Figure 1.
The non-return valve shown in the drawings comprises
a valve housing 1 having a through passage 2, in which a valve
seat 3 closed by a flap 4 is disposed. Said flap 4 is sup-
ported on a swivel shaft 5 whose ends are supported in the
valve housing 1. A biassing weight 6 is also supported on the
same swivel shaft 5. In the no-flow state of the valve the
bias-sing weight 6 holds the flap 4 on the valve seat 3. On
its side ad;acent the flap 4 the biassing weight 6 has a
follower detent 7 provided with a damping layer 8 of an
impact-damping material. On the underside of the flap 4 there
is disposed a rib 9 forming having its end a counterdetent 10.
A limit stop 11, which may also be provided with a damping
layer or be formed of an impact-damping material, is disposed
above the swivel shaft 5 in the valve housing 1 on the outside
wall of the through passage 2.
As seen in Figure 2 the flap 4 and the biassing
weight 6 are supported on the same swivel shaft 5. On the
underside of the flap 4 the rib 9 with the counterdetent 10
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can be seen and U-shaped arms 12 having on each end a swivel
support 13 of the flap 4 extend from the rib 9. The biassing
weight 6 having a supporting borehole 14 is slipped onto the
swivel shaft 5 between the two swivel supports 13. The detent
7 with the damping layer 8 is disposed between the two swivel
supports 13. It is evident that the damping layer 8 rests
hard against the counterdetent 10 of the rib 9 of the flap 4.
At rest, i.e., when no flow medium is passed through
the through passage 2 of the valve housing l, the flap 4 rests
hard against the valve seat 3 and is held in this position by
the biassing weight 6. As soon as th~ flow medium is passed
in the direction of the arrow 15 through the through passage 2
it lifts the valve flap 4 from the valve seat 3 against the
closing force exerted by the biassing weight 6 so that the
flow medium can flow through the valve housing 1. At the same
time the flap 4 is swung together with the biassing weight 6
until the biassing weight 6 rests against the limit stop 11.
In this position (not shown) the flap 4 in Figure 1 extends
approximately vertically downwards so that the entire passage
cross section of the valve seat 3 is clear and the flow medium
can flow through the non-return valve 1 without obstruction.
The biassing weight 6 biasses the flap 4 in the
closing direction. As soon as the flow of medium stops there
results a return flow in the opposite direction through the
through passage 2. This return flow also acts on the flap 4
in the closing direction. The return flow picks up the flap 4
and pushes it onto the valve seat 3 in the direction of the
arrow 16 in Figure 1. As indicated by a dot-dash line in
Figure 1 the flap 4 is leading the biassing weight 6 since
said weight is a unit separate from said flap. Therefore, the
closing motion can proceed rapidly since only the relatively
small mass of the flap 4 must be accelerated. Because of its
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great weight the biassing weight 6 follows with less accelera-
tion until the detent 7 with the damping layer 8 impinges on
the counterdetent 10 of the flap 4 and thus holds it on the
valve seat 3.
The small mass of the flap 4, which must be acceler-
ated by the return flow, ensures that the valve closes ra-
pidly. Furthermore, the small mass of the flap 4 causes the
flap 4 to strike valve seat 3 softly. This prevents the flap
4 from rebounding after impinging on the valve seat 3 and from
lifting the valve seat once more for a short period. The wear
and the danger of breaking also are correspondingly reduced.
After closing the valve a pressure difference builds up
between the two sides of the flap 4, keeping the valve
securely closed.
