WO2006131125A1

WO2006131125A1 - Fresh air valve

Info

Publication number: WO2006131125A1
Application number: PCT/DK2006/050023
Authority: WO
Inventors: Mogens Madsen
Original assignee: Form & Plast A/S
Priority date: 2005-06-06
Filing date: 2006-05-31
Publication date: 2006-12-14
Also published as: DK176163B1; EP1917483A1

Abstract

The building-in depth for fresh-air valves (2) is dependent on the type and positioning of the sealing strip, in that the necessary flow area for the open valve is determinative for how much the valve damper (6) must be displaced to its fully open position. There is disclosed a fresh-air valve (2) of the kind which comprises slot-shaped channel bushes (4) for building into slot shaped openings, covered by a ventilation damper (6) housed in pressure-releasable snap-couplings, which offers a smaller building-in depth than the known fresh-air valves, but at the same time offers the same free-flow area for air passing through the fresh-air valve in its open position, and which also offers a more effective protection of the pressure- releasable displacement couplings against dirt, which is achieved by the placing of the pressure-releasable displacement couplings in a first and second coupling sink (10, 10') respectively positioned at each end of the channel bush (4), that the through-flow opening is placed between said coupling sinks, and that the sealing strip (16) comprises a lip-ring placed in a recess (18) extending around the through-flow opening (22) of the channel bush.

Description

The present invention relates to a fresh-air valve of the kind which comprises a housing for building into a slot-shaped opening in walls or frames, for example window frames, and comprising an elongated ventilation damper with ends which at the ends of the housing are connected to pressure releasable snap-couplings which can be activated between an open and a closed position for the ventilation damper.

Examples of such fresh-air valves are known from WO 90/10777, i.e. a valve with an elongated slot which by means of respective pressure-operable snap- couplings is connected at both ends with opposing sides of a flat channel bush in such a manner that the damper plate, from an open position at a distance in front of the mouth of the channel bush, can be pressed in to a self-retaining closed posi- tion, from which is can be opened by spring pressure after a subsequent brief, further pressing-in. The valve can appear completely without operating elements, and since the damper plate is connected with the snap-couplings in a lengthwise pivotal manner, it is without significance whether it is pivoted in a crooked manner during the inwards and outwards displacement.

The locking principle used is thus the same as that which in a simple embodiment is known from ball-point pens, through with a somewhat stronger configuration of the snap-couplings. Use is made of a coupling system based on a metallic spring hook which is controlled sideways in cooperation with a sloping cam surface on the outer telescopic part of the coupling. However, this arrangement has proved to display various less fortunate aspects, such as the spring hook being difficult or expensive to produce with the necessary degree of precision, and that the couplings in themselves are not easily mounted, and moreover the couplings are of a size which entails a relatively large building-in depth, and therefore require the removal of relatively large amounts of material from that surface in which the fresh-air valves is to be mounted, which with the present demands regarding effectiveness is not desirable.

Another locking principle is known from GB 2352270, which comprises a pressure-operated inwards/outwards displacement coupling, primarily for use in connection with a closing and opening of a damper plate in a ventilation valve. The coupling is configured with a coupling element which against a spring pressure can be pressed into a surrounding guide part, and which provided with a guide ca ring a u urning ac ions o e coup ing sys em a is can provisionally be secured in a pressed-in position, from which it can be released to an outwardly-displaced position by a further, brief pressing-in. The special aspect of the invention is that there is hereby provided a robust snap-lock effect by configur- ing the guide cam as an injection moulded item on an outwardly flexible wall section of the guide part, and which cooperates with track parts with different directions, bottom depths and inclinations. This snap-lock thus incorporates two spring systems, firstly a coil spring which ensures the inwards and outwards displacement of the coupling element, and secondly the fact that the walls of the guide part comprise slots which, combined with a flexible configuration of the walls of the guide part, enable the walls to be pressed out as a flexible tongue part, which makes it possible for the guide cam to be locked in the pressed-in position, and moreover that by a renewed pressure can be displaced out in the track to the displaced outwards position. This displacement coupling, in comparison with the cou- pling disclosed in WO 90/10777, has the advantage that it is more simple in execution, and it is considerably easier to mount, but this does not solve the problem regarding the large building-in depth for the fresh-air valve.

The known fresh-air valves typically comprise a sealing strip of foam rubber or plastic foam which is glued on that side of the ventilation damper which faces towards the channel bush and along its outer edge. By the pressing-in of the displacement coupling to the ventilation damper's closed position, the sealing list is pressed against a contact surface on the facing side of the channel bush, and by this closing of the ventilation damper there occurs a compression of the insulating material, so that the ventilation damper is flush with the channel bush. In the opening of the ventilation damper there occurs a subsequent expansion of said sealing strip to the original volume/thickness. Said expansion results in a reduction of the slot opening in the open fresh-air valves, which in order to achieve the necessary ventilation capacity of the valve, makes necessary a relatively large displacement of the ventilation damper in the direction away from the mouth of the channel bush. This has been the reason why it has hitherto been necessary to have to accept the relatively large building-in depth of the above-mentioned pressure operated snap-couplings. A further disadvantage with the known fresh-air valves is that the positioning of the sealing strip along the outer edge of the ventilation damper results in the pressure-operated inwards and outwards displacement couplings having to be placed within the flow opening of the channel bush, which means that with time these become sullied with dust etc. which exists in the ventilation air which passes through the flow opening. This sullying can with time result in a re- , _ _,. , uction of t e unc iona ity o t e pressure-operate displacement couplings, i ne placing of the sealing strip along the outer edge of the ventilation damper also has the result that at half opening of the fresh-air valve, i.e. when only the one of the pressure-operated couplings is displaced, the parts of the strip which are placed on the outer sides of the pressure-operated displacement couplings are clamped extra strongly against the recess of the channel bush as a consequence of the tilting of the damper plate, which results in increased deformation of said sealing strip.

It is thus the object of the invention to provide a fresh-air valve which offers a smaller building-in depth than the known fresh-air valves , but which at the same time offers the same free-flow area for air passing through the valve in the open position of the valve.

A further object of the invention is to provide a fresh-air valve which offers a more effective protection of the pressure-operated displacement couplings against dirt, and it is also endeavoured to provide a fresh-air valve where the sealing strip in not exposed to unnecessarily hard loading with one-sided opening of the fresh- air valve.

With the invention, it has been realised that with a fresh-air valve of the kind disclosed, it will be possible to solve the above-mentioned problems, said valve being characterised in that the pressure-operated displacement couplings are placed respectively in a first and a second coupling sink provided in each end of the channel bush, and that the through-flow opening is placed between said coupling sinks, and that the sealing strip consists of a lip-ring which is placed in a recess extending in and around the through-flow opening of the channel bush.

It is hereby achieved that as a result of the placing of the sealing strip in the annular recess in the channel bush, the opening height for the ventilation damper can be reduced, the reason being the sealing strip does not herewith occupy space in the opening area of the fresh-air valve. This provides the possibility of being able to reduce the movement that the pressure-operated displacement couplings shall describe between the open and the closed position of the valve damper, and herewith the possibility of reducing the building-in height for the fresh-air valve. By the pressure-operated displacement couplings being placed in special coupling sinks which are separate from the flow opening of the channel us , ere is ur er ac eve e a van age a e pressure-operate nwards and outwards displacement couplings are better protected against dirt.

With the view of placing the sealing strip as close as possible to the outer side of the valve, it can be an advantage for the lip-ring to be moulded together with the channel bush by two-component injection moulding.

The advantage can hereby be achieved that the necessary open height is reduced with the height of the sealing strip, in that the sealing list is placed in the recess in the channel bush. Moreover, two-component moulding provides the advantage that the operation which is connected with the gluing/mounting of the sealing strip is hereby eliminated.

With the object of optimising the production process in the manufacture of the fresh-air valve according to the invention, the ventilation damper can consist of an elongated, tubular, flattish profile of rigid or partly rigid material which can be accommodated in the annular recess in the channel bush, said tubular, flattish profile having a first curved side surface and a second curved side surface, which in combination form a cavity for accommodation and pressing-in of projecting tongues on end pieces which form a part of the pressure-releasable snap couplings, and where the breadth of the second curved side surface is less than the breadth of the first curved surface, so that the second side surface herewith appears with parallel-extending side lobes for contact against the lip-ring.

It is hereby achieved that the tubular, flattish profile can be adapted in length by a right-angled cut, which considerably simplifies the manufacturing process in comparison with a valve damper with rounded end parts, and material wastage is also counteracted since the consequence of the rounding off will be that material which shall be removed can not be reused.

In a second embodiment of the tubular, flattish profile, this can comprise a slot in the second curved side surface. There is hereby achieved a saving of the material which is involved in the manufacture of the valve damper.

However, it has also been realised with the invention that the normal and desired rounding-off of the ends of the valve damper can be retained by configuring the coupling sinks and the end parts with a rounding on the opposite side of the projecting tongue which is accommodated in the tubular, flattish profile. With the view of ensuring a good seal between the coupling sinks and the slot opening in the channel bush, the sides of the coupling sinks facing towards the slot opening can have a concave extent which is approximately similar to the second curved side surface of the elongated, tubular, flattish profile, and over which concave extent the sealing strip extends.

The fresh-air valve's channel bush is typically made of injection moulded plastic and is a relatively thin-walled construction which, when being pressed into a window frame or sill, can sometimes break. With the view of giving the channel bush an adequate stability, a number of transverse bridges can be provided in the slot opening of the channel bush.

In the cases where the extent of the bridges in the extent of the channel bush is desired to be spread to maximum breadth, the end parts of the bridges facing towards the damper can be shaped with a rounding which corresponds to the second curved side surface of the tubular, flattish profile which constitutes the fresh- air valve's damper.

With the view of providing the fresh-air valve with a smooth and easy-to- clean surface, the end parts can comprise a curved surface congruent with the first curved surface of the ventilation damper, whereby the valve cover and the end parts appear as an almost unbroken extent which is easy to dry off with a cloth in connection with cleaning.

With the view of providing a reduced building-in height for the fresh-air valve, and a simplification of the pressure-re leasable snap-couplings, the respective end parts can comprise a projecting part oriented opposite to the curved surface, which parts are cooperating with and inwardly-displaceable coupling sinks, in that the projecting part end part comprises protruding guide cams which cooperate with guide tracks at least in two opposing and towards the end parts facing sides of the first and the second coupling sink respectively, and that the end parts further comprise a cavity for accommodating a compression spring in which there is housed the first leg of a substantially U-shaped snap element, so that the compression spring rests against the bottom of the U-profile, and in extension of the bottom said U-shaped snap element further comprises a protruding retaining cam for accommodation in a herewith cooperating recess/hole in the side of the coupling sink, and where the other leg of the U-shaped snap element comprises a protruding retaining cam element oriented towards and engaged in a track system comprising a rac orien e in para e wi e ongi u ina axis o e pro ruding part, the en of which comprises a labyrinth comprising a V-shaped switch point with a first track which is deeper than the second, and in the middle of which there is an upstanding retaining part with a pointed extent, and whose opposite ends comprise a stepped seating cooperating with the retaining cam element, and where the track depth in the first track, in between the pointed extent and the stepped seating, is decreasing and wherein, by the pressing in of the end parts to a bottom position, the retaining cam element is guided in to the stepped seating, whereby the ventilation damper is provisionally locked in an active closed position, pressed against the lip-ring, and where a re-pressing of a relevant end part will result in the releasing of the retaining cam element from the stepped seating and a guiding sideways in to the V.-shaped switch point's second track, the bottom of which lies lower, whereby the retaining cam element is released from the stepped seating and guided via the second track, the depth of which is decreasing towards the track oriented in parallel with the longitudinal axis of the protruding part, under outwards displacement of the part to an open passive position for the ventilation damper.

There is hereby achieved an integration of the end pieces and the pressure- releasable snap-couplings, where the end pieces now constitute an integrated part of these. Moreover, with the protruding guide cams on the end part, which cooperate with guide tracks in at least two opposing and towards the end pieces facing sides of respectively the first and the second coupling sink, there is achieved a considerably better guiding of these during the displacement of these between the outer positions, and the user is hereby given an impression of greater stability dur- ing the operation of the fresh-air valves. Furthermore, with the new construction of the valve's pressure-releasable snap-couplings, with the U-shaped snap element which with its arrangement solves several tasks, namely the holding firm of the damper in the open and closed positions respectively, and the retaining of the end pieces in the coupling sinks, it is achieved that these aspects in combination pro- vide the possibility for a smaller building-in height for the fresh-air valve. At the same time, with the special configuration of the pressure-releasable snap- couplings, it is achieved that the spring which by pressure on the pressure.- releasable snap-couplings displaces the end pieces outwards in relation to the channel bush, and herewith also the damper, is further utilised to hold the retaining cam element in engagement with the stepped seating for provisional locking of the damper in the closed position in contact with the sealing strip. ., in trie o owing, e inven ion is exp aine in more e ail witn reterence to the drawing, where

Fig. 1 is a perspective view of a fresh-air valve for building into a slot-shaped opening in walls or frames, for example window frames, according to the invention, Fig. 2 is an exploded perspective view of the fresh-air valve shown in fig. 1 , Fig. 3 is a plan view of fig. 2,

Fig. 4 is a perspective length-section view of the one end of the fresh-air valve shown in fig. 1 - fig. 3, where the valve damper is in the open position, Fig. 5 is perspective length-section view of the one end of the fresh-air valve according to the invention as shown in fig. 4, but as a line drawing,

Fig. 6 is perspective view of the one end of the fresh-air valve, shown in fig. 5, and

Fig. 7 is a perspective length-section view of the one end of the fresh-air valve shown in fig. 1 - fig. 6, where the valve damper is in the closed position.

In fig. 1 is shown a perspective view of an embodiment of a fresh-air valve 2 according to the invention. As will immediately appear from figs. 1 , 2, 3, 4 and 5, the fresh-air valve 2 comprises a channel bush 4 and a damper 6, which is an- chored in the end pieces 8, 8', which are housed in coupling sinks 10, 10' at the ends of the channel bush 4. The channel bush 4 also comprises an outer side 12, protruding locking cams 14 (in the shown embodiment, 4 on each side of the channel bush), for the retention of the fresh-air valve 2 in the walls in a relevant slot-shaped opening (not shown) in which the fresh-air valve is placed.

As will appear from fig. 2, 3 and 4, the fresh-air valve further comprises a sealing strip 16 which comprises a lip-ring and is placed in a recess 18 extending all the way around the edge 20 of the through-flow opening 22 of the channel bush. As appears clearly from fig. 5, at each end the fresh-air valve further com- prises, cooperating with the end parts 8, 8', substantially U-shaped snap elements 24, 24'and, cooperating with these, spring elements 26, 26' in the form of coil springs.

In the through-flow opening 22 of the channel bush 4 there are also a number of transverse bridges 28 for the strengthening of the channel bush.

As will appear from figs. 2, 3 and 4, the end parts 8, 8' comprise protruding tongues 30, 30' which are designed for engagement in the cavity 32 of a tubular, flattish profi e w c consttutes t e actua valve damper 6. Said tubular proπie can, for example, consist of rigid or partly rigid material, e.g. aluminium. The tubular flattish profile 6 comprises a first curved surface 33 which forms the outer side of the valve damper 6, and a second curved side surface 34, which in combination define the cavity 32 for the pressing-in of the tongues 30, 30' of the end pieces 8, 8'. The breadth of the second curved surface 34 is less than a breadth of the first curved surface 36 for contact against the sealing strip 16.

As will appear from figs. 2, 4 and 5, the side edges of the coupling sinks 10, 10' facing the through-flow opening 22 have a concave extent which is almost congruent with the second curved side surface of the valve damper 6, and where the sealing strip 16 extends, and the protruding tongues 30, 30' on the end pieces 8, 8' , on the sides facing the sealing list 16, have a corresponding curved extent 38, whereby in the closed position of the valve damper, cf. fig. 7, this surface of the end pieces 8, 8' is pressed against the sealing strip.

As appears especially in fig. 2, the end pieces 8, 8' have curved surfaces 40, 40' congruent with the first curved surface 34 of the valve damper 6.

The end pieces 8, 8', which constitute a part of the pressure-releasable snap- couplings for the valve damper, further comprise a protruding part 42, 42' which is inwardly displaceable and cooperating with the coupling sinks 10, 10', in that the protruding parts 42, 42' on the end pieces 8, 8' comprise protruding guide cams 44 which cooperate with tracks 46, 46' (cf. fig. 5) in two opposing sides of the first and second coupling sink 10, 10', these sides facing towards the end parts. The end parts 8, 8' further comprise a cavity for receiving the compression spring 26 and the first leg 47 of the U-shaped snap element 24, 24', so that the one end of the compression spring rests against the bottom 48 of the U-shaped snap elements 24, 24'. In extension of the bottom of the U-shaped snap elements 24, 24', at the foot of the second leg 49 of the U-shaped snap element, there is a protruding retaining cam 50 designed for engagement in a herewith cooperating hole 52 in the side of the coupling sinks 10, 10'.

The second leg of the U-shaped snap elements 24, 24' further comprises a retaining cam 54 which is oriented towards and engaged in a track system 56 in the side 58 of the protruding parts 42, 42' facing towards the walls of the coupling sinks, as will appear from fig. 5 and fig. 6. The track system comprises a length axis of the protruding parts 42, 42,' length axis parallel oriented track 60, which towards trie curve sur aces , compr ses a a yr nt wnn a v-snapeα switch point 64, the first track 66 of which is deeper than the second 68, and in the centre of said labyrinth there is an upstanding holding part 70 with a pointed extent oriented towards the track 60. The opposite end of the holding part 70 comprises a stepped seating 72, this cooperating with the retaining cam element 54, where the track depth is decreasing between the pointed extent and the stepped seating 72, and in which the retaining cam element 54, by a pressing-in of the end parts 8, 8' to a bottom position, are guided into the stepped seating 72, whereby the retaining cam element 54 is locked, as will appear from fig, 7, and is retained in this position by the force of the spring element 26, so that the ventilation damper 6 is provisionally locked in a position where its lobes 36 are pressed against the sealing list, until a renewed pressing of a relevant end part 8, 8', alternatively both end parts, will result in the retaining cam element being released and guided out from the stepped seating 72, and under the effect of the spring element 26 on the end part(s) 8, 8', guided out sideways and into the V-shaped switch point's second track 74, the bottom of which lies lower than the bottom of the stepped seating, and is led under outwards displacement of the end parts 8, 8' via the second track 64 back to the track 60, which is oriented in parallel with the length axis of the protruding parts 42, 42^'.

In connection with the mounting of the pressure-releasable snap-couplings, with the introduction of the protruding retaining cam 50 in the hole 52 there occurs a locking of the end pieces 8, 8', so that these, in combination with the retaining cam element 54 and its seating in the track system, are secured in the coupling sinks 10, 10'.

The mounting of the fresh-air valve takes place by the pressing of the tongues 30 of the end parts 8, 8' into the cavity 32 of a hereto adapted, tubular flattish profile which constitutes the valve damper 6 itself. Hereafter, there is placed a spring element 26, 26' on the first leg 47 of each of the U-shaped snap elements 24, 24' which are then inserted in the cavity arranged for this purpose in the end parts 8, 8', at the same time that the retaining cam element 54 on the second leg 49 of the U-shaped snap element 24 is placed in the track system 56 on the outer side of the protruding parts 42, 42', after which the end parts are intro- duced into the coupling sinks 10, 10' until the retaining cams 50 are engaged in the holes 53 in the coupling sinks, after which the fresh-air valve is assembled. With t e nventon t ere s t us provided a fresh-air valve wnich with its construction permits a reduced building-in depth as a consequence of a new placing of the sealing strip 16 in a recess 18 in the opening 22 of the channel bush 4. This has further led to an optimisation of the pressure-releasable snap-couplings, since the end parts 8, 8' serve as a part of these, in that the channel bush 4 comprises herewith cooperating coupling sinks 10, 10', with which in combination with a newly-developed U-shaped snap element 24, a spring element 26 and a track system in the end parts 8,8', there is thus achieved the desirable reduction in the building-in height, and the placing of the pressure-releasable snap-couplings in closed coupling sinks protects these against sullying by dirt. Moreover, there is provided a fresh-air valve which is considerably cheaper to produce, and with pressure-releasable snap-couplings which are considerably easier to assemble.

Claims

1. Fresh-air valve (2) of the kind which comprises an elongated channel bush (4) with a substantially slot-shaped through-flow opening (22) for building into a slot-shaped opening in walls or frames, for example window frames, and further comprising an elongated ventilation damper (6) with ends which are connected to pressure-releasable snap-couplings arranged near the ends of the housing, where said pressure-releasable snap-couplings can be activated between an open and a closed position for the valve damper (6), and where between the channel bush (4) and the ventilation damper (6) there is provided a sealing strip (16), c h a r a c t e r i s e d in that the pressure-releasable snap-couplings are placed respectively in a first and a second coupling sink (10, 10') which are located in each end of the channel bush (4), that the through-flow opening (22) is placed between said sinks (10, 10'), and that the sealing strip (16) consists of a lip-ring which is placed in a recess (18) in and extending around the through-flow opening (22) of the channel bush.

2. Fresh-air valve (2) according to claim ^ c ha r a c t e r i s e d in that the sealing strip (16) is moulded together with the channel bush (4) by two-component injection moulding.

3. Fresh-air valve (2) according to claim 1 or 2, c h a r a c t e r i s e d in that the ventilation damper (6) consists of an elongated, tubular, flattish profile (6) of rigid or partly rigid material, which can be accommodated in the channel bush (4), said tubular, flattish profile (6) having a first curved side surface (33) and a second curved surface (34), which in combination form a cavity (32) for receiving and the pressing-in of protruding tongues (30) on the end parts (8, 8') which constitute a part of the pressure-releasable snap-couplings, and where the breadth of the second curved side surface (34) is less than the breadth of the first side surface (33), so that the second side surface (34) hereby appears with parallel-extending side lobes (36) for contact against the sealing strip (16).

4. Fresh-air valve (2) according to claim 3, c h a r a c t e r i s e d in that the tubular flattish profile (6) comprises a slot in the second curved side surface (34).

5. Fresh-air valve (2) according to claim 3 or 4, c h a r a c t e r i s e d in that the sides of the coupling sinks (10, 10') facing towards the through-flow opening (22) have a curved extent which is approximately congruent with the second curved side surface (34) of the elongated, tubular, flatfish profile (6).

6. Fresh-air valve (2) according to any of the claims 1-5, c h a r a c t e r i s e d in that a number of transverse bridges (28) are provided in the slot opening (22) of the channel bush.

7. Fresh-air valve (2) according to any of the claims 1-6, c h a r a c t e r i s e d in that the end parts (8, 8') comprise a curved surface (40) which is congruent with the first curved surface of the ventilation damper (33).

8. Fresh-air valve (2) according to any of the claims 1-7, c h a r a c t e r i s e d in that the respective end parts (8, 8') constitute a part of the pressure- releasable snap-couplings, where these comprise a protruding part (42, 42') ori- ented opposite the curved surface (40, 40'), said parts cooperating with and which can be inserted in the coupling sinks (10, 10'), where the protruding part (42, 42') on the end parts (8, 8') comprises protruding guide cams (44, 44') which cooperate with guide faces (46, 46') in at least two opposing sides facing towards the sides of the end parts of the first and the second coupling sink (10, 10') respectively, and that the end parts (8, 8') further comprise a cavity for receiving a compression spring (26) in which there is housed the first leg (47) of a substantially U-shaped snap element (24), so that the compression spring (26) rests against the bottom (48) of the U-shaped profile, and where in extension of the bottom (48) the U- shaped snap element (24) further comprises a protruding retaining cam (50) for engagement in a herewith cooperating cut-out/hole (52) in the sides of the coupling sinks (10, 10'), and where the second leg (49) of the U-shaped snap element comprises a protruding retaining cam element (54) oriented towards and engaged in a guide track system (56) comprising a track (60) oriented in parallel with the length axis of the protruding part, the one end of said track comprising a labyrinth (62) having a V-shaped switch point (64), the first track (66) of which is deeper than the second track (68), and where in the centre of which there is an upstanding retaining part (70) with a pointed extent oriented parallel towards the length axis track (60) of the protruding part, and the opposite end of which comprises a stepped seating (72) cooperating with the retaining cam element, and where the track depth in the first track (66), between the pointed extent and the stepped seating (72), is decreasing, and wherein the retaining cam element (54), by pressed the end parts (8, 8') in to a bottom position, is guided into the stepped seating (72) whereby the ventilation damper (6) is provisionally locked in active closed position, pressed against the sealing list (16), and where a renewed pressing of the relevant end parts (8, 8') will result in the retaining cam element (54) being released from the stepped seating (72) and guided sideways and into the V-shaped switch point's second track (68), the bottom of which is lower-lying, and led via the second track (68), the depth of which is decreasing towards the parallel-oriented track (60) of the protruding part's length axis, under an outwards displacement of the part(s) (42, 42') to an open passive position for the ventilation damper.