A fresh air valve with a locking mechanism for a cover plate

Abstract

 A fresh air valve (1) which comprises an elongated housing (2) with an elongated slot shaped through flow opening (21) for building into elongated slot shaped openings in walls or frames, for example window frames, the through flow opening comprising two end walls (22,23), one end wall arranged at either end of the through flow opening, and an elongated cover plate (3) which is displaceably arranged in the elongated housing to be displaceable between two positions, a closed position in which the through flow opening is closed and an open position in which the through flow opening is at least partially open. The elongated cover plate comprises two engagement elements (41), one arranged at either end of the elongated cover plate and both arranged inside the through flow opening, the elongated housing comprises two locking mechanisms (40), one arranged at each end of the elongated housing and both arranged outside the through flow opening and the locking mechanisms engage with the engagement elements of the elongated cover plate through two small openings (45), one small opening placed in each end wall of the through flow opening. In this way a fresh air valve is provided with a well functioning and simple way of locking the cover plate in its closed position.

Description

[0001] The current invention relates to a fresh air valve of the kind which comprises an elongated housing with an elongated slot shaped through flow opening for building into elongated slot shaped openings in walls or frames, for example window frames, the through flow opening comprising two end walls, one end wall arranged at either end of the through flow opening, and said fresh air valve further comprising an elongated cover plate which is displaceably arranged in the elongated housing to be displaceable between two positions, a closed position in which the through flow opening is closed and an open position in which the through flow opening is at least partially open.

Description of related art

[0002] Fresh air valves of this kind are well known in the art. Some different examples are disclosed in DE20011184U1, DK122840B, GB2311848B, US7393271B2, WO9010777A1, WO9735087A1, EP1917483A1 and EP2231985A1.

[0003] These prior art documents all disclose fresh air valves having various disadvantages. For example, some of the valves disclose a complicated and fragile locking mechanism. Others disclose a locking mechanism which is difficult to assemble. Others disclose a locking mechanism which is prone to getting jammed with dirt over time. Others disclose an expensive construction of the cover plate. Others disclose a complicated seal arrangement between the housing and the cover plate. Others are prone to condensation problems due to the poor insulating abilities of the cover plate. Others are complicated to use.

Summary of the invention

[0004] The current invention seeks to provide a fresh air valve of the kind as mentioned in the opening paragraph but which is better than the ones known from the prior art.

[0005] This is provided in that the the elongated cover plate comprises two engagement elements, one arranged at either end of the elongated cover plate and both arranged inside the through flow opening, in that the elongated housing comprises two locking mechanisms, one arranged at each end of the elongated housing and both arranged outside the through flow opening and in that the locking mechanisms engage with the engagement elements of the elongated cover plate through two small openings, one small opening placed in each end wall of the through flow opening. In this way a simple arrangement is provided where the moving parts of the locking mechanisms are arranged away from the through flow opening and the cover plate and its associated engagement elements are arranged in the through flow opening. In this way, the cover plate and the locking mechanisms can be more easily separated to provide a more simple locking mechanism. This also allows for a more simple design of the cover plate and its associated seal.

[0006] Other innovative features are described in the dependent claims.

[0007] It should be emphasized that the term "comprises/comprising/comprised of" when used in this specification is taken to specify the presence of stated features, integers, steps or components but does not preclude the presence or addition of one or more other features, integers, steps, components or groups thereof. For example, in the claims it is stated that the cover plate has two positions, a closed position and an open position. However, this should be understood in the context of the current specification as "at least" two positions. It should be understood that the scope of the claims includes fresh air valves having cover plates which can assume more than two positions.

Brief description of the drawing

[0008] In the following, the invention will be described in greater detail with reference to embodiments shown by the enclosed figures. It should be emphasized that the embodiments shown are used for example purposes only and should not be used to limit the scope of the invention.

Figure 1 shows a top perspective view of a first embodiment of a fresh air valve according to the invention, where the cover plate is in its open position.

Figure 2 shows a top perspective view of the fresh air valve of figure 1 with the cover plate in its closed position.

Figure 3 shows a cross section view of the fresh air valve of figure 1 according to the line III-III defined in figure 1.

Figure 4 shows a top perspective exploded view of the fresh air valve of figure 1.

Figure 5 shows a top perspective detail exploded view of one end of the fresh air valve of figure 1.

Figure 6 shows a close-up perspective view of the push button of the locking mechanism of the fresh air valve of figure 1.

Figure 7 shows a bottom perspective view of the fresh air valve of figure 1.

Figure 8 shows a top view of the fresh air valve of figure 1.

Figures 9-11 schematically show the function of the locking mechanism of the fresh air valve of figure 1.

Figure 12 shows a bottom perspective view of the cover plate of the fresh air valve of figure 1.

Figure 13 shows a cross section view of the cover plate of figure 12 according to the line XIII-XIII defined in figure 12.

Figure 14 shows a top perspective view of the cover plate of figure 12.

Figure 15 shows a cross section view of the cover plate of figure 12 according to the line XV-XV defined in figure 12.

Figure 16 schematically shows the function of a second embodiment of a locking mechanism.

Figure 17 schematically shows the function of a third embodiment of a locking mechanism.

Figure 18 schematically shows the function of a fourth embodiment of a locking mechanism.

Detailed description of the embodiments

[0009] Figures 1-15 are all related to the same embodiment of a fresh air valve, and as such the reference numerals used will be the same. Figures 16-18 relate to separate embodiments of a locking mechanism suitable for use with a fresh air valve.

[0010] The first embodiment 1 of a fresh air valve according to the invention comprises an elongated housing 2, a cover plate 3, two push buttons 4,5, two springs 6,7 and two fastening clips 8,9. The fastening clips and the springs are of the kind which are known to the person skilled in the art and as such these will not be described in more detail in this specification.

[0011] The fresh air valve is of the kind which can be mounted in an elongated slot in wall or frame. One typical example of the use of such a valve is in a window frame. Typically, a slot is machined in a window frame and the fresh air valve is inserted in the slot by pressing it into the slot. It can be see that the ends of the housing are semi-circular. This fits well with the fact that when machining a slot in a frame, it is typical to use a router with a circular cutter. Therefore, the start and end of the slot will be rounded. The rounded ends of the housing therefore match the rounded ends of the machined slot. A small overhang 20 on the top of the housing ensures that small manufacturing tolerances in the machining of the slot are covered by the fresh air valve. The clips 8,9 are arranged to grip onto the bottom and/or the sides of the housing and when the housing is pressed into the machined slot, the edges of the clips will dig into the sides of the slot, thereby holding the housing fixed in the machined slot.

[0012] Furthermore, the width and length of the machined slot in the window frame are chosen to match the width and length of the housing. In this way, the fresh air valve fills the slot completely and a tight fit can be formed between the outer sides of the housing and the inner sides of the machined slot. This prevents unwanted air flow between the sides of the slot and the outer sides of the housing. In certain cases, it might be desired to apply a seal between the outer side of the housing and the inner sides of the slot.

[0013] The housing further comprises an elongated slot shaped through flow opening 21. The through flow opening in this embodiment is rectangular with a length which is greater than its width. The through flow opening has two end walls 22,23, one end wall arranged at each end of the through flow opening and two side walls 24,25, one side wall arranged along each longitudinal side of the through flow opening. The through flow opening allows air to flow through the housing when the through flow opening is not blocked. The through flow opening is arranged as an elongated channel having a length, a width and a depth, the length axis being parallel with the longitudinal axis of the elongated housing. When built into a wall or frame, the area defined by the length and the width is the through flow area and the depth would be arranged perpendicular to the outer surface of the wall or frame. The housing further comprises two wells 26,27, one arranged at either end of the housing. The wells are arranged on the "outside" of the end walls of the through flow opening. By "outside" is meant further from the center of the housing. The push buttons 4,5 are arranged in these wells as will be described later on in this specification. In order to strengthen the housing and the through flow opening, a number of strengthening ribs 28 are provided in the through flow opening. The strengthening ribs 28 are connected to opposing side walls and are arranged perpendicular to the side walls. The ribs therefore span the through flow opening.

[0014] In order to prevent airflow through the through flow opening when desired, a cover plate 3 is provided. The cover plate 3 is in the current embodiment arranged as a rectangular plate having dimensions so that it can block the through flow opening and block air flow through it. The cover plate is arranged such that it can assume at least two positions. In a first position, an open position, the cover plate is arranged so that air can flow through the through flow opening and in a second position, a closed position, the cover plate is arranged so that air cannot flow through the through flow opening.

[0015] In one embodiment, the cover plate could be arranged to fit inside the through flow opening like a plug and thereby block the air flow through it. In another embodiment, the cover plate could be arranged slightly larger than the through flow opening like a cover over the through flow opening. In the current embodiment, the through flow opening is provided with a shoulder 30 onto which the cover plate can be fitted in the closed position of the cover plate. The dimension of the shoulder is arranged such that the cover plate can be pushed into the through flow opening, thereby allowing the top surface of the cover plate to be flush with the top surface of the housing.

[0016] As can best be seen in figure 3, the cover plate is provided with a co-injected seal 31. More details of the seal 31 are provided later on in this specification. The seal 31 is arranged on the bottom surface of the cover plate and is arranged to press against the shoulder 30 in the through flow opening when the cover plate is in its closed position, thereby ensuring that an essentially air tight seal is provided between the housing and the cover plate. Furthermore, as can best be seen in figure 3, the cover plate is provided with an internal stringer 32 to provide extra stiffness. More details of the construction of the cover plate will be provided later on in this specification.

[0017] Springs 6,7 arranged between the cover plate and the housing at each end of the cover plate ensure that the cover plate is biased away from the housing, thereby biasing the cover plate into its open position. When it is desired to close the housing, the cover plate is pressed in towards the housing thereby counteracting the bias of the springs.

[0018] In order to hold the cover plate in its closed position, locking mechanisms 40,50 are provided at each end of the housing which are engageable with engagement elements 41,51 arranged at either end of the cover plate. In the current embodiment the engagement elements are provided on the bottom of the cover plate, whereby they are hidden from view when the cover plate is in its closed position. When the cover plate is pressed into its closed position, the engagement elements on the cover plate, engage the locking mechanisms thereby holding the cover plate in place. When it is desired to open the cover plate, the locking mechanisms are unlocked thereby releasing the engagement elements of the cover plate and allowing the cover plate to displace into its open position due to the bias of the springs.

[0019] In the current embodiment, the locking mechanisms are independent of each other. As such one of the locking mechanisms could be unlocked while the other one was locked. This allows the cover plate to assume a position where it is partially closed and arranged diagonally in the opening. This also means that in order to close the cover plate, one could either press both ends of the cover plate to simultaneously engage both sides of the cover plate with the locking mechanisms at both ends of the housing which requires two hands or one could first press one end of the cover plate thereby engaging that end of the cover plate with the locking mechanism at one end of the housing then one could press the cover plate at the other end, thereby engaging that end of the cover plate with the locking mechanism at the other end of the housing.

[0020] In the current embodiment, it can also be noted that each side of the cover plate can assume one of two stable positions. The first position is completely open, the other is completely closed. In another embodiment (not shown) the locking mechanism could be arranged to allow the ends of the cover plate to assume a number of different positions, for example, by providing the locking mechanism or the engagement elements with a ratchet type mechanism. This would provide a fresh air valve where the air flow through the valve could be controlled more precisely.

[0021] The locking mechanism and the engagement element will now be described in more detail. The function of the locking mechanism can best be explained with reference to figures 9-11. For the sake of simplicity, only the locking mechanism and engagement element at the left side of the fresh air valve as shown in the figures will be discussed. However, the locking mechanism and the engagement element at the right side of the fresh air valve are identical.

[0022] The engagement element 41 is in the form of a "hook" projecting from the bottom of the cover plate element. The hook comprises a first elongated flexible portion protruding from the bottom of the cover plate. At the end of this flexible portion, a protrusion is formed. The hook could also be described as a leg or an L shaped member. The locking mechanism is in the current embodiment in the form of a plastic injection moulded push button 4, or activation element, arranged displaceably in the well 26 of the housing 2. The push button is arranged to be displaceable along an axis which is essentially parallel to the air flow through the through flow opening. It could also be said that the push button is arranged to be displaceable along an axis which is perpendicular to the cross sectional area of the through flow opening.

[0023] In figures 9-11, it can be seen that the push button comprises two "legs" 42, 43 extending from the bottom of the push button. Each leg is formed as an elongated flexible protrusion protruding from the bottom of the push button. One leg 42 is arranged with a protrusion 44 which extends out through a small opening 45 in the end wall 22 of the through flow opening. The leg 42 is however arranged to be flexible and by bending the leg 42, the protrusion 44 can be retracted from the small opening 45. As can be seen in figures 9-11, the bottom surface of the protrusion is formed with a sloped surface 46 which is in contact with an edge of the small opening 45 in the end wall 22. Due to the sloped surface of the protrusion, when the push button is pressed down into the well, the protrusion is forced to retract from the small opening, thereby causing the leg 42 to bend. When the push button is released, the stiffness of the leg 42 causes the leg to want to return to its normal position, thereby causing the protrusion to again extend out through the small opening and thereby the push button moves up again due to the sloped surface.

[0024] As can also be seen from figures 9-11 the bottom surface 47 of the engagement element is also formed with a sloped bottom. In this way, when the engagement element is pushed downwards and the bottom surface of the engagement element meets an edge, the edge is either forced to the left (according to the orientation in the figures) or the engagement element is forced to the right. This situation is shown in figure 9.

[0025] Figures 9-11 also show the second leg 43. The second leg is also formed as a hook element. The hook element of the second leg, allows the push button to be inserted into the well and then the hook element of the second leg engages with a slot 48. When the push button moves up and down in the well, the hook element of the second leg slides up and down in the slot 48, but the hook element prevents the push button from moving too far up and falling out of the well. The push button is also formed with two guiding legs 49 (not shown in figures 9-11, but shown in figures 4 and 5). The two guiding legs are arranged perpendicular to the upper surface of the push button and are arranged in slots 50 in the well. The slots and the guiding legs ensure that the push button moves up and down in the well.

[0026] In general, the figures show one specific embodiment of a locking mechanism. However, it should be clear to the person skilled in the art that the locking mechanism could perform the same function but have a different form. For example, in the current embodiment, the guiding legs have the function of ensuring that the push button slides up and down along a well defined path. The second leg 43 can be said to have the function to ensure that the push button does not fall out of the well and has a well defined top position. The first leg 42 has the function of guiding the protrusion in and out of the small opening. Therefore, the locking mechanism can be said to have three main functions, a guiding function, a top position defining function and a protrusion moving function. These three functions could be arranged with other physical means than the ones used in the shown embodiment.

[0027] Figure 9 shows what happens when the cover element is moved from its open position to its closed position. As the cover element is pushed down into the housing, the bottom surface 47 of the engagement element comes into contact with the top edge of the protrusion 44. As the cover element is pushed further down, the protrusion 44 is pushed further into the small opening 45. The engagement element 41 may also be pushed to the right, an amount depending on the strength difference between the first leg 42 of the push button and engagement element 41. Once the protrusion has been pushed all the way into the small opening, the engagement element can pass the protrusion. As soon as the engagement element has passed the protrusion, the protrusion snaps out again (as shown in figure 10) due to the elasticity of the first leg 42. The engagement element is then held in place by the protrusion and the cover plate kept in place in its closed position.

[0028] Figure 11 shows what happens when the push button is pushed into the well when the cover plate is in its closed position. In this case, the sloped surface 46 of the protrusion 44 is pushed against the edge of the small opening 45. This forces the protrusion to retract into the well. Once the protrusion is retracted enough, the engagement element will release the protrusion, and the cover plate will be forced outwards into its open position due to the bias of the springs.

[0029] In order to ensure that the cover plate does not fall out of the housing, two stabilizing elements 60 are arranged at each end of the cover plate. These stabilizing elements are also in the form of a hook and hook onto the bottom surface 61 of the shoulder 30 of the through flow opening in the open position of the cover plate. The bottom surface 61 can be seen in figures 9-11. Since there are two stabilizing elements at each end of the cover plate, one at each corner, the stabilizing elements help to prevent the cover plate from twisting in the opening.

[0030] It should be noted that the engagement elements arranged on the bottom surface of the cover plate are arranged inside the through flow opening, while the locking mechanisms are arranged on the outside of the through flow opening. In this way, the locking mechanisms are kept separate from the through flow opening. The interaction between the locking mechanisms and the engagement elements occurs via the small openings in the end walls.

[0031] Figures 12-15 show more details of the cover plate 3 of the fresh air valve shown in figures 1-11. As mentioned earlier in this specification, the cover plate is manufactured via an injection moulding process out of a plastic material. In order to give strength and stiffness to the cover plate, an aluminium stringer 32 is provided inside the cover plate 3. It could be said that the cover plate comprises an outer shell 33 and a stringer element 32 enveloped inside the outer shell 33. In particular, it can be said that the material of the outer shell 33 is arranged to physically lock the stringer element to the outer shell, thereby ensuring that the cover plate feels like a single integrated element which does not need to be manually assembled and which cannot fall apart. In the current embodiment the outer shell almost completely surrounds the stringer element so that only a very small percentage of the outer surface of the stringer element is exposed.

[0032] During manufacturing, the aluminium stringer 32 is arranged inside the empty mould and held in place in the correct position. Plastic material is then injected into the mould, thereby surrounding or enveloping the aluminium stringer with plastic. During the injection moulding process, the aluminium stringer is held in place by support elements in the mould. These support elements occupy space in the mould, and the plastic cannot fill the space occupied by the support elements. This can be seen by the grooves 34 in the cover plate. In this way, a small amount of the outer surface area of the stringer element is exposed after the injection moulding process is completed.

[0033] Furthermore, as mentioned previously, the cover plate also comprises a seal 31 arranged around the periphery of the cover plate. This seal could be arranged in different ways, but is in the current embodiment formed during the injection moulding of the cover plate in the same mould. The mould is a two position mould, where in a first position, the outer shell of the cover plate itself is moulded by injecting a hard plastic into the mould cavity. Once the plastic material of the cover plate is sufficiently cooled, the mould is put into its second position whereby a new cavity is formed into which a second plastic material is injected. This second plastic material could be softer than the first plastic material and is suitable for forming a seal. Since the seal is formed during the injection moulding of the cover plate, no assembly is required for the cover plate. The cover plate comes out of the mould completely assembled. Also the engagement elements 41 and the stabilizing elements 60 are injection moulded in the current embodiment, again in the same mould as the outer shell of the cover plate. In this way, a cover plate is provided which is a very simple and robust part.

[0034] In the current embodiment, the cover plate is manufactured with a single aluminium stringer 32 having a T shaped cross section. However, within the scope of the current invention, the cover plate could be arranged with different forms of stringers. For example, in one embodiment, not shown, the stringer could be manufactured from a fibre reinforced composite material, for example pultruded polyurethane with a high composition of glass fibres. In another embodiment, not shown, instead of a single T shaped stringer, two separate L shaped stringers could be arranged in the cover plate. Many other forms of stringers could be imagined which increase the stiffness of the cover plate.

[0035] Furthermore, in the current embodiment, the cover plate is formed as a plastic injection moulded component with integrated engagement elements and stabilizing elements. However, in another embodiment (not shown), the cover plate could be formed via an extrusion or pultrusion process, where the body of the cover plate is formed via the extrusion or pultrusion process and the engagement elements and/or stabilizing elements are fastened to the cover plate after the extrusion/pultrusion process. Furthermore, the seal could be formed as a co-extruded component along the sides of the cover plate. A seal for the ends of the cover plate could be fastened to the cover plate when the fastening and/or stabilizing elements are fastened to the cover plate.

[0036] Figure 16 shows a second embodiment of a locking mechanism 100 suitable for a fresh air valve according to the current invention. In this embodiment, a protrusion on the engagement element 101 is arranged to snap into the small opening 102 in the end wall 103 of the through flow opening. The inner surface 104 of the end wall 103 is formed slightly sloping in towards the centre of the through flow opening. In this way, as the engagement element is displaced downwards, it is forced towards the centre of the through flow opening. When the engagement element reaches the small opening 102, the engagement element snaps into the opening and holds the cover plate in place.

[0037] The push button 110 is again formed with two legs 111, 112. The second leg 112 has the same function as in the first embodiment, however, the first leg is slightly different. In this embodiment, the first leg also has a protrusion, but it does not protrude into the small opening in its rest position. The bottom of the well is formed with a sloped protrusion 113 which lies up against the first leg 111. As the push button is pushed downwards, the sloped protrusion 113, causes the protrusion on the first leg to be pushed into the small opening. The protrusion on the first leg then pushes against the engagement element, thereby pushing it out of the small opening, thereby allowing the cover plate to again displace towards its open position.

[0038] The embodiment 120 of figure 17 is very similar to the embodiment of figure 16, so only a short description of this embodiment will be provided. The main difference is that the protrusion 121 which pushes the engagement element out of the small opening is separated from the push button. In this way, the protrusion 121 can be formed to make an air tight seal with the small opening. This allows the fresh air valve of this embodiment to be even more sealed in the closed position than the previous embodiments.

[0039] The embodiment 130 of figure 18 is of a slightly different form. Instead of a push button, it has a slider 131. As the slider 131 is displaced to the left, the protrusion 132 is withdrawn from the small opening 133, thereby releasing the engagement element 134. Another embodiment (not shown) similar to a combination of figure 18 and figure 17 could also be imagined, where a slider button like the one in figure 18 is used to push an engagement element out of the housing like in figure 17.

[0040] It is to be noted that some of the figures and the above description have shown the example embodiments in a simple and schematic manner. Certain mechanical details might have been removed since the person skilled in the art should be familiar with these details and they would just unnecessarily complicate this description and/or the figures. For example, in many of the figures, the springs 6,7 were removed to simplify the drawings.

Claims

1. A fresh air valve (1) of the kind which comprises

- an elongated housing (2) with an elongated slot shaped through flow opening (21) for building into elongated slot shaped openings in walls or frames, for example window frames, the through flow opening comprising two end walls(22,23), one end wall arranged at either end of the through flow opening, and

- an elongated cover plate (3) which is displaceably arranged in the elongated housing to be displaceable between two positions, a closed position in which the through flow opening is closed and an open position in which the through flow opening is at least partially open,

characterized

- in that said elongated cover plate comprises two engagement elements (41), one arranged at either end of the elongated cover plate and both arranged inside the through flow opening,

- in that the elongated housing comprises two locking mechanisms (40), one arranged at each end of the elongated housing and both arranged outside the through flow opening and

- in that the locking mechanisms engage with the engagement elements of the elongated cover plate through two small openings (45), one small opening placed in each end wall of the through flow opening.

2. A fresh air valve (1) according to claim 1, characterized in that said locking mechanisms (40) each comprise a displaceable protrusion (44) which is arranged to be displaceable between:

a) a locking position in which the protrusion protrudes through the small opening (45) in the end wall (22,23) of the through flow opening (21) in which position said protrusion is engageable with the engagement element (41) of the cover plate (3) in the closed position of the cover element to lock the cover element in its closed position and

b) a non-locking position in which the protrusion is retracted such that it protrudes less through said opening and such that it is not engageable with the engagement element of the cover plate.

3. A fresh air valve (1) according to claim 1 or 2, characterized in that the engagement elements (41) of the cover plate (3) are arranged below the top surface of the cover plate.

4. A fresh air valve (1) according to any one of claims 1-3, characterized in that the elongated slot shaped through flow opening (21) is rectangular.

5. A fresh air valve (1) according to any one of claims 1-4, characterized in that the cover plate (3) is rectangular.

6. A fresh air valve (1) according to any one of claims 2-5, characterized in that each locking mechanism (40) comprises an activation element (4,5), which when activated, causes the protrusion (44) of the locking mechanism (40) to displace from its first position to its second position.

7. A fresh air valve (1) according to claim 6, characterized in that the activation element (4,5) is arranged to be displaceable in a direction having a component which is perpendicular to the cross sectional area of the through flow opening (21).

8. A fresh air valve (1) according to claim 7, characterized in that the activation element (4,5) comprises an elongated flexible member (42) extending in a direction which is essentially parallel to the displacement direction of the activation element, and where the protrusion (44) of the locking mechanism (40) is fastened to the end of the elongated flexible member,

a) said elongated flexible member further comprising a sloped surface (46), which is arranged to contact an edge or surface of the housing, such that when the activation element is displaced, the sloped surface slides along the contact edge or surface of the housing (2) and displaces the protrusion in a direction which is essentially perpendicular to the direction of displacement of the activation element, or

b) said housing comprising a sloped surface, which is arranged to contact an edge or surface of the elongated flexible member, such that when the activation element is displaced, the contact edge or surface of the elongated flexible member slides along the sloped surface and displaces the protrusion in a direction which is essentially perpendicular to the direction of displacement of the activation element.

9. A fresh air valve (1) according to claim 8, characterized in that the activation element (4,5), the elongated flexible element (42) and the protrusion (44) are all formed as a single plastic injection moulded part.

10. A fresh air valve (1) according to any one of claims 2-9, characterized in that the engagement element (41) and the protrusion (44) are arranged such that when the cover plate (3) is displaced from its open position to its closed position, the protrusion is displaced from its first position to its second position, to allow the engagement element to pass the protrusion, and once the engagement element has passed the protrusion, allow the protrusion to move from its second position to its first position, thereby locking the cover plate in its closed position.

Drawing