TECHNICAL FIELD

The proposed device is applied as a self-sealing back draft damper (check valve), completely preventing the backflow through air ventilation appliances and systems, such as for example domestic exhaust fans and extractor hoods. It is applicable as an additional accessory for already operating ventilation appliances or it can be provided as an add-on device for future appliances to be build. A possible use as a stand-alone device inside of air ducts or at the vents is also feasible.

BACKGROUND OF THE INVENTION In contemporary homes the ventilation of bathrooms and kitchens is mainly achieved by the use of exhaust fans and extractor hoods conveying the air from the ventilated rooms to a vent. Under unfavorable weather conditions and combined with the fact that the fans and extractor hoods are being switched off for most of the time, the unhindered backflow of air leads to the occurrence of odors and moisture in the ventilated rooms and in the living space in general.

The market offer basically self-sealing back draft dampers in the form of butterfly valves, throttle valves, slats. As a consequence of their design, unavoidable gaps appear between the movable parts and the nonmoving sections of these devices. Even being minimal, the unwanted backflow of air from the vent to the ventilated room will become recognizable if in addition to moisture also strong odors are being transported.

Back draft dampers for domestic use operating with a ball as a closing member are described in the granted patent US5509445 and the published patent application US2006/0200896 Al. The check valve described in patent US5509445 hinders the backflow of air from outside to the home's interior through the ventilation opening. The ball is moving within a curved duct at whose lower end, as a separate part, a ring-shaped seat is mounted. The published patent application US2006/0200896 Al describes a self- sealing ventilation check valve for bathrooms and toilets. Two embodiments of the check valve are presented. In its first embodiment the check valve is installed onto a suspended ceiling, the ball is moving within in an elbow duct. By reaching a rim coupled with a padding the ball closes the check valve. In the second embodiment enlisted in the same patent application, the ball is moving in a cylinder-shaped duct having slots on its periphery. To close the valve, the ball rolls to a flange which is formed at the inlet of the duct. The duct is mounted with an inclination of 5°-10° relative to the horizontal plane. Within the application no requirements concerning the diameter of the ball and the inner diameter of the duct were specified, but following the drawings one may conclude that the ball fits tight into the duct, which is necessary when the valve has to be tightly closed. In this case, however, the unhindered movement of the ball could be obstructed or fully blocked if the duct is being deformed or impurities are present inside of it.

The described valves contain additional parts in particular with complicated shapes or specially formed edges and gaskets, the dimensions of the ball and the duct have to be precisely adjusted, which is crucial for the valve to provide an airtight seal. If these requirements are not fulfilled, a gap may appear when the ball contacts the gasket and the airtight seal will not be provided. The descriptions represent layouts containing one tube (duct). The inlet of the check valve and the ball have to be with sufficient dimensions in order to enable an optimal airflow, which would ask for an increase of the overall dimensions of the check valve and may lead to an unhandy mounting.

The present invention proposes a self-sealing back draft damper which is free from the above mentioned drawbacks, by constructing a back draft damper, being cheap and technologically not-demanding in production and mounting, providing an airtight seal against unwanted backflow, dependably operating for extended periods of time. The present invention eliminates the requirement for the precise adjustment between the dimensions of the individual parts of the valve. In addition to the layout suited for appliances ventilating bathrooms, a layout suited for kitchen extractor hoods is proposed. Embodiments containing more than one tube are proposed.

DISCLOSURE OF THE INVENTION

A self-sealing back draft damper for a complete prevention of backflow air, such as through ventilation appliances and systems, is proposed. It preferably includes a valve housing formed as a hollow body having entering and exit openings with a valve body inside the housing. According to the invention, the housing has at least One exit opening and can have more than one mounting holes and inside the valve housing, there is, at least one tube of preferably circular cross section with decreasing diameter along its axis - a conical tapered tube or another way saying a tube with frustoconical shape, with an axis inclined with respect to the horizontal plane, which can be regarded as a stationary valve body with a low-lying narrow end. The low lying narrow end of the conical tapered tube is airtightly fixed to the corresponding mounting hole of the valve housing, whereupon fixed in this way the narrow open end of the tube acts as a conical tapered inlet of the damper. The housing and the valve bodies may be provided as a unity part without the need of mounting holes. At least one aperture, enabling airflow out of the tube towards the exit openings of the valve housing have to be available on the tube contained inside the housing, preferably formed on the surface of the tube. Inside the body of the tube, there is a preferably spherical closing member with a possibility for free movement, whose diameter is smaller than the inner diameter of the larger end of the tube and comparable but not smaller than the inner diameter of the narrow end of the conical tapered tube. The damper is shut and the air cannot pass if the sphere is at the low-positioned narrow end of the valve body- at the conical tapered inlet inherently formed by the decreasing diameter of the tube. When the damper is at open position, the closing member is away from the inlet and without a possibility to leave the tapered tube through its larger end. Preferably, the length of the tube and its location within the housing can be such that the spherical closing member is being prevented to leave the tube by part of the surface of the housing without the need of additional protectors placed at the larger end of the tube. The weight of the spherical closing member and the slope of the tapered tube are such that in absence of airflow in the direction to the exit opening of the valve, the closing member is self-positioned at the conical tapered inlet and the spherical closing member can overcome the inclination on its path and is away from the inlet under force directed to the vent resulting from a pressure difference appearing between the exit openings and the inlet. The air flow can be drawn into the inlet preferably with a ventilation appliance. However, a self-ventilation is also possible.

95 This layout of the self-sealing damper, which contains at least one conical tapered tube with an axis, which is inclined, with respect to the horizontal plane, is in particular well suited for mounting the damper by airtightly attaching its site with the exit openings by means to the entrance of a fan. In a preferred arrangement, the exit openings are on the one side of the housing and the mounting holes are on the opposite site. Further, 100 depending on the chosen arrangement, on the housing of the damper more than one mounting holes may be foreseen, with more than one valve bodies inside the housing being attached to each of them, whereby increasing the airflow. This layout describes also a stand-alone damper, mounted directiy at a vent, inside of an air duct or behind a ventilation appliance.

105 Another preferred layout of the self-sealing damper incorporates a case in which the axis of the conical tapered tube is oriented vertically with respect to the horizontal plane. In this layout the spherical closing member has a possibility of almost vertical motion within the tube and without the possibility to leave the tube from the available apertures and openings. The mounting hole lies in the horizontal plane and the narrow

110 end of the conical tapered tube is airtightly fixed to it. This layout is preferably recommended if the damper is to be mounted directly by proper means at the exhaust of a kitchen extractor hood or in a vertically oriented flue. If the damper is mounted at the exhaust of a kitchen extractor hood, it is recommended that the spherical closing member is made of heat-resistant material. The damper may contain more than one vertically

115 oriented valve bodies. In a preferred arrangement, the exit openings are on the one side of the housing and the mounting holes are on the opposite site.

An additional manipulator could be mounted for the case that the spherical closing member has to be moved by force if the damper is mounted without offering a direct access to the closing member. Depending on the layout the manipulator may be

120 implemented by a spring or a lever.

In all described layouts of the self-sealing damper, the spherical closing member is preferably a hollow body, made of material resisting to deformations for example a ping pong ball or a hollow sphere made of aluminum alloy.

In another layout of the self-sealing damper, the apertures available on the tapered

125 tube are additionally equipped with protectors in order to prevent the spherical closing member against leaving the tube.

It has also to be noted that in order to increase the airflow through an open damper, the damper may be a hollow body containing inside of it more than one valve bodies carried out as conical tapered tubes, whose axes, depending on the layout,

130 arrangement and further requirements, are inclined or vertically oriented relative to the horizontal plane, or a combination of both, whereupon each valve body also contains one spherical closing member.

The main advantage of the proposed damper is its ability to prevent completely the occurrence of a backflow through exhaust fans and extractor hoods by means of an

135 easily build- and mounted device, being dependable in operation, containing non- expensive parts, not demanding a precise adjustment of the dimensions of the closing member and those of the valve body. The possibility for more than one valve bodies to be mounted inside the housing, enables the airflow through the damper to be increased without the need of an extensive increase of the overall dimensions of the damper. By

140 choosing a conical tapered tube with an inherently formed conical tapered inlet as a valve body containing the movable spherical closing member, the need for implementing of further rims, padding and flanges within the inlet of the valve body is omitted since the spherical closing member completely shuts the inlet of the valve when it stops at the position where the diameters of the tube and the sphere become nearly equal. The

145 continuous increase of the diameter of the conical tapered tube along its axis enables the free movement of the spherical closing member within the tube's entire volume. The damper with any of the preferred layouts can be mounted horizontally, vertically or inclined with respect to the horizontal plane depending mainly on the arrangement of the exit holes of the valve housing. The device fully prevents external odors and humidity

150 from entering the ventilated areas which represents a major issue in nowadays multi-story residential buildings. Moreover, if favorable winds- or conditions triggering even a weak airflow are present, the air pressure difference emerging between both sides of the valve body will be sufficient for the damper to open and to let an airflow to pass to the vent. In this way a self-initiating ventilation becomes possible and the long-term absence of air

155 exchange is prevented.

BRIEF DESCRIPTION OF THE DRAWINGS

Fig. 1 is a cross-sectional view of the self-sealing back draft damper of the invention 160 caried out with an inclined conical tapered tube as a valve body

Fig. 2 is a schematic view in direction A from Fig. 1

Fig. 3 is a schematic view in direction B from Fig. 1

Fig. 4 is a cross-sectional view of the self-sealing back draft damper of the invention caried out with a vertically oriented conical tapered tube

165 Fig. 5 is a schematic view in direction A from Fig. 4

BEST MODES OF CARRYING OUT THE INVENTION

Two preferred embodiments of the self-sealing damper are shown in Figs. 1 to 5. A valve 170 housing 1 made as a hollow body has exit openings 2 formed on it as shown in Figs.l and 3. A tube 3 with a lengthwise decreasing diameter, conical tapered tube or another way saying a tube with frustoconical shape, intersects with its narrow end a mounting hole 10 formed on the surface of the housing 1, and is being fixed airtight to it. The conical tapered tube 3 is mounted inclined with respect to the horizontal plane. The lower- 175 positioned narrow end of the tube 3 forms a conical tapered inlet 6 where the airflow is entering through. From the surface of the conical tapered tube 3, at least one aperture 4 is cut which is entirely located inside the housing 1. The dimensions of the aperture 4 are chosen sufficientiy large, so that an unobstructed airflow through the aperture out of the tube towards the exit 2 of the valve housing is possible. The apertures may be in a form 180 of strips. Another arrangement may be that instead of having an aperture 4, the air is going out of the tube through the larger end of the tube 3. A spherical closing member 5, made preferably hollow and of an non-deforming material, for instance a ping pong ball, moves freely inside the tube between the part 9 of the housing's 1 surface and the conical tapered inlet 6 at the narrow end of the conical tapered tube 3. The length and the 185 position of the tube are such as the closing member 5 shall not be able to leave the tube. An alternative arrangement is to have protectors placed at the larger end of the tube 3 in order to stop the spherical member. The diameter of the spherical closing member 5 is smaller than the inner diameter of the conical tapered tube 3 at its largest section and is similar, but not smaller than the inner diameter of the tube 3 at its narrowest section. At

190 the working position of the damper as shown in Fig. 1, in absence of an airflow towards the vent, the closing member 5 is self -positioned at the lower narrow end of the conical tapered tube 3 and seals the conical tapered inlet 6 of the damper. The damper is airtightly attached preferably to the entrance of an exhaust fan by a sealing strip 7 or by other properly suited means. The tiny protector 8 is added if the damper is used in

195 combination with a powerful fan, or if the spherical closing member may leave the tube through the aperture 4. As an option, the described back draft damper could be fixed directly to the vent as a stand-alone device, or it may be positioned on the path of the airflow following an exhaust fan or an extractor hood.

Another preferred embodiment at which the axis of the conical tapered tube 3 is

200 vertically oriented is shown in Fig. 4. This embodiment is recommended to be used in combination with a kitchen extractor hood, mounted preferably directly at the exhaust of the extractor hood. A conical tapered tube 3 intersects with its lower-positioned narrow end a circular mounting hole formed in the horizontal plane on the surface of the housing 1, made as a hollow body, and reaches the opposite surface 9 of the housing. On the

205 surface of the tube, apertures 4, placed entirely inside the housing are formed, to which protectors 8 are being attached if necessary, and their dimensions are sufficient for an airflow to pass through unobstructed. In this case, on the surface of the housing 1, exit openings 2 are formed as shown in Fig. 5, whose dimensions are sufficient for the unobstructed passage of an airflow through them, while protecting at the same time the

210 spherical closing member 5 from leaving the housing 1. The length of the tube is such as to prevent the closing member to leave the tube. The spherical closing member moves freely inside the tube within the space limited by the section 9 from the surface of the housing 1 and the conical tapered inlet 6 of the tube 3. If used with the kitchen extractors, the spherical closing member is preferably made as a hollow body of light and

215 heat-resistant material e.g. aluminum alloy. Due to the specific circumstances of the recommended application of this embodiment, optionally a manipulator 11, depending on the design it could be made also as a spring or a lever, is foreseen in case the spherical closing member 5 has to be enforced to move. By means of proper seals 7 the damper is preferably mounted inside the exit duct 12 of the kitchen extractor hood, without the duct

220 being disrupted, whereby the entire airflow to the flue is driven through the damper.

Another embodiment comprises a valve body which is not mounted inside a hollow body, for instance the valve body is airtightly fixed, preferably vertically or inclined with respect to the horizontal plane, at its narrow end to a mounting hole, which is cut on a plate, the latter is airtightly fixed into an air duct. In this case a protector is

225 mounted at the larger end of the tapered tube in order to prevent the spherical closing member to leave it. Alternatively the conical tapered tube with a build-in protector at its wide end, is directly fixed to an air duct by means of a sealing compound.

In order to increase the airflow, the damper may contain more than one conical tapered tubes 3 mounted inside the housing 1, whereby the axes of the tubes are inclined

230 or vertically oriented, or both in one housing, relative to the horizontal plane and each tube contains one spherical closing member 5. Certainly, the housing and the valve bodies may be manufactured as one detail and not as separate components.

One of the advantages of the damper using a conical tapered tube as a valve body with preferably spherical closing member is that the spherical closing member 5 being pushed by an occurring backflow will be pressed tightly against the conical tapered inlet 6 of the tube 3, being mounted as described, thereby completely blocking the backflow. If the spherical closing member 5 is manufactured with a shape maximal close to the spherical one, without bumps, irregularities on the surface or visible joints and the the cross section of the tube being maximal close to the pure circular one, the sealing when damper is closed will show no gaps and will be basically hermetic.

In the layout containing a slightly inclined conical tapered tube 3 with the spherical closing member 5 moving inside, the damper remains closed if there is no airflow from the ventilated space to the vent, since the spherical closing member 5 self settles at the narrow end of the conical tapered tube 3 and seals the inlet 6 of the damper. It is advantageous that the rolling movement of the spherical closing member 5 proceeds with a minimum drag. Even if the ventilation appliance remains switched off, the inlet 6 will be opened if the minimal pressure difference between both sides of the damper, required for the spherical closing member 5 to be moved upwards inside the conical tapered tube 3, is exceeded. Consequently, if the spherical closing member 5 is manufactured as a low-weight hollow sphere, made of light and tough material, as for example a ping pong ball, even unsupported by a ventilation appliance, the back draft damper will conduct an airflow if the proper conditions for establishing of an even weak airflow to the vent becomes present. The damper will close if the airflow vanishes or changes its direction.

The inlet 6 is fully opened when the ventilation device is working and the closing member 5 is retracted. Being pushed by the airflow, the closing member 5 settles at the opposite end of the conical tapered tube 3, the airflow is directed from the conical tapered inlet 6 through the aperture 4 of the tube, towards the exit openings 2 and the vent.