HK1164954B - Air admittance valve - Google Patents

Description

Air inlet valve

Technical Field

The present invention relates to a closing and sealing device for use in an air admission valve connected to a sanitary waste water pipe system, in order to protect the water trap in the system and prevent the air contained in the waste water or sewer system from communicating with the ambient atmosphere, said valve opening automatically in the event of a sudden pressure drop or negative pressure peak within said pipe system, to admit atmospheric air into the pipe system.

By closing and sealing means it is understood that on the one hand a movable closing member or membrane and on the other hand a stationary valve seat cooperating with the closing member in the sealing position of the valve.

Background

Under normal operating conditions, building drainage and ventilation systems require the establishment of an intake air flow within the vertical ducts (vertical stacks) of the system due to unstable offal produced by sanitary discharges. In order to protect the living space from contaminated odors, each of the devices is usually protected by a water trap. Variations due to the drainage within the drainage system produce occasional changes (positive and/or negative) in air pressure which can often upset these trap seals by siphoning due to sudden negative pressure in the system or by creating back pressure by closing off the air passage with excess water.

Air inlet valves have been employed to avoid this inconvenience and, since the valves only open in response to sub-atmospheric pressure in the waste pipe system, the necessity of venting the waste pipe system outside the roof of the building can be avoided.

The valve is designed to ensure the maximum possible inlet air flow from the air inlet of the valve to the waste pipe system while passing through the temporarily opened valve membrane.

There is a difference between the two main types of inlet valves, the first type comprising an annular closing member resting on two coaxial circular seats and the second type comprising a spherical or circular closing member resting on a corresponding peripheral seat.

One of the first automatic intake valves is disclosed in document BE 831833.

The more recent patent document US4232706 by the applicant of the present application discloses an automatic valve device in which the vertical pipe constituting the valve body comprises at its upper end a formation in the form of a venturi cooperating with a cover so as to form a peripheral air inlet provided with an annular valve member external to the formation, and which is able to tilt when a negative pressure occurs in the pipe, while allowing the entry of fresh air into the vertical waste water pipe, and which is in a closed position, preventing the escape of contaminated air when the pressure is balanced or when an overpressure occurs. The valve comprises an annular peripheral opening which, with the annular valve member raised, distributes the air inlet towards a vertical pipe connected to the waste water pipe.

In such valves, a circular or annular valve member typically rests on two concentric valve seats each having a circular sealing surface. The necessary hermetic sealing of the valve member or membrane with at least one of the two sealing surfaces can present problems in case the valve member is deformed or distorted.

Document EP0409506 discloses a valve device for admitting air into a conduit comprising a body mountable on the conduit, a chamber in the upper part of said body provided with at least one first passage to the interior space of the conduit, a central circular closure member and a second passage within said body for communication between ambient air and the chamber when the closure member is raised. The closing member is usually guided by a guiding means, such as a central rod. The sealing between the movable valve part and the sealing is achieved by means of an O-ring provided on the sealing surface or a rubber disc provided on the closing part.

Document EP1650363 discloses an intake valve having substantially the same structure as the device described above. The sealing member includes an elastomeric sealing membrane held by an upper membrane support and a lower membrane support. When the valve is in the sealing position, the sealing membrane abuts against a sealing lip of the air inlet wall.

The manufacture of the closing member or membrane in the known device is complex and expensive, since it is made of several parts of different composition, rigid and/or flexible material. Another major drawback of existing inlet valves is the accuracy of the sealing capacity between the closing member or membrane and the sealing surface or valve seat. In practice, the sealing surface is mostly rigid or comprises a fixed ring (O-ring). Minor changes in the flatness of the closure member and/or sealing surface due to temperature or material deformation may cause leakage and release of contaminated air from the sewer system to the surrounding atmosphere.

Disclosure of Invention

It is an object of the present invention to provide an improved air inlet valve which is very simple and easy to manufacture, while providing improved sealing capacity and sealing reliability.

The above object is achieved according to the features of the present invention described in detail in the following aspects.

According to an aspect of the present invention there is provided an air admittance valve to be connected to a sanitary waste water pipe system for admitting atmospheric air into the waste water pipe system towards a valve seal in response to a sudden pressure drop in the waste water pipe system so as to protect a water trap in the waste water pipe system and to prevent contaminated air from being discharged from the waste water pipe system to the atmosphere, the air admittance valve comprising a valve housing comprising: a vertical tubular member connectable to the waste water piping system and having an interior space; a cap or cover located at an upper end of the valve housing and having an interior space; a valve opening between the vertical tubular member and the cover and a valve sealing arrangement comprising a fixed valve seat co-operable with a movable closure member at the periphery of the valve opening; at least one passage from the interior space of the valve housing to the ambient atmosphere; at least one passage from the interior space of the cap or cover within the valve housing to the interior space of the vertical tubular member; said passages being in contact with an upper or lower surface of said movable closing member, respectively, so as to lift said movable closing member when there is a sudden loss of air pressure in said waste water pipe system to allow fresh air to enter into said waste water pipe system via said passages leading from the interior space of said valve housing to the ambient atmosphere in order to equalize the air pressure within said waste water pipe system, characterized in that said movable closing member comprises a rigid movable member having the shape of a circular poppet valve provided with a conical peripheral collar having a reverse angled conical surface extending upwardly at an angle α, said circular poppet valve further being provided with an inverted bowl-shaped interior whose upper central area extends at a level higher than the level of the upper peripheral edge of said reverse angled conical surface, and the circular poppet valve cooperates with the upper edge of the fixed valve seat, which is provided with an annular soft seat having a thin annular cantilever platform or lip extending toward the center of the valve opening.

According to another aspect of the invention, there is provided a method for closing and sealing the above-mentioned air inlet valve connected to a sanitary waste water pipe system and comprising a movable rigid closing member in the shape of a circular poppet valve and a fixed valve seat with an annular soft seat, characterized in that during an equilibrium air pressure condition or positive air pressure in the waste water pipe system, the movable circular poppet valve is brought to rest in a normal position against the valve seat, in the case of negative pressure in the waste water pipe system, the movable circular poppet valve is lifted from the valve seat, the lifting force is improved by the shape of the inverted bowl-shaped interior of the valve and the conical surface provided with an inverted angle at its periphery, and the upward movement of the circular poppet valve is limited due to the abutment of the central upper part of the inverted bowl-shaped interior of the valve against the lower surface of the cover of the valve housing, in the event of overpressure in the waste pipe system, the movable circular poppet valve is caused to be pressed down against the soft cantilevered edge of the annular soft seat, thereby flexing it downward to increase the sealing surface between the movable circular poppet valve and the annular soft seat.

Drawings

Further details, advantages and features of the invention will become apparent from the following description of an embodiment of the valve of the invention with reference to the accompanying drawings, in which:

FIG. 1 is a cross-sectional view of a valve housing provided with a sealing arrangement according to the present invention, showing a passageway to the ambient atmosphere;

FIG. 2 is an enlarged view of detail A of FIG. 1 with the closure member in a closed or sealing position;

fig. 3 is a cross-sectional view of the valve housing, taken in a plane perpendicular to the plane in fig. 1, showing access to the interior space of the sewer system;

FIG. 4 is an enlarged view of detail B of FIG. 3 with the closure member in the open or raised position;

FIG. 5 is the same partial cross-sectional view as FIG. 3, showing some alternative construction features;

FIG. 6 is a cross-sectional view taken along line C-C in FIG. 5, showing an example of a valve guide; and

fig. 7 is a detailed sectional view of a poppet valve according to the present invention.

Detailed Description

As shown in fig. 1 and 3, the valve comprises a conventional inlet valve housing 10 having a lower portion comprising a vertical tubular member 12 having an interior space 19 and adapted to be connected to a vertical conduit of a sanitary waste water conduit (not shown) which is part of a sewer system.

The upper part of the valve housing 10 is closed by a cap or cover 14. Between the cover 14 and the tubular member 12, the housing is normally provided with a passage 16 to the surrounding atmosphere and a passage 18 to the inner space 19 of the tubular member 12 and thus to the sewer system (fig. 3).

The channels 16 and 18 are connected to each other by means of a central circular valve opening 20, the upper edge of said central circular valve opening 20 acting as a fixed valve seat (seal) 22 designed to cooperate with a movable closing member 24.

The lower surface 26 of the movable closure member 24 is in contact with an internal valve space 30, which internal valve space 30 is connected to the passageway 16 to the surrounding atmosphere, and the central upper portion (surface) 28 of the movable closure member 24 is in contact with a space 32 within the upper lid 14, which space 32 is connected to the passageway 18 to the internal space 19 of the tubular member 12.

The passageway 16 and the internal valve space 30 are isolated from the internal space 19 of the tubular member 12 by a closing wall 21 which is part of the valve housing 10.

According to the invention, the movable closing member 24 is designed in the shape of a (circular) reversible poppet valve 40 provided with an inverted bowl-shaped interior 42, the lower surface of which interior 42 is permanently in contact with atmospheric pressure. It will be readily appreciated by those skilled in the art that the bowl-shaped lower surface of the reversible poppet valve 40 provides an increased surface contact with atmospheric air and will therefore significantly increase the lifting power of the closure member 24 in the event of negative pressure in the sewer system.

Preferably, the inverted bowl-shaped interior 42 of the reversible poppet valve 40 will be provided with a peripheral collar having a reverse angled conical surface 44 extending upwardly at an angle α (fig. 2) toward an upper edge 45. The angle may be between 20 ° and 45 °, and is preferably about 30 °.

The lower surface of the inverted bowl shaped interior 42 is in contact with the surrounding atmosphere and will provide good lifting force of the reversible poppet valve 40 in the event of sudden negative air pressure at the upper surface of the reversible poppet valve 40.

To further improve the lifting force of the reversible poppet valve 40, the reverse angled conical surface 44 is slightly curved along a circle of radius R. The radius R is approximately equal to the diameter of the central circular valve opening 20 (see fig. 7).

Preferably, the level of the top of the inverted bowl-shaped interior 42 will be at a higher elevation than the height of the upper edge 45 of the reverse angled conical surface 44.

The lower surface of the inverted bowl-shaped inner portion 42 is provided at its centre with a tubular extension 46 designed to co-operate as a guide with a stem 48 rigidly connected to the closing wall 21 of the valve housing 10. According to a preferred embodiment, the stem 48 is provided with a star-shaped outer surface (as shown in fig. 6), so as to minimize friction between the tubular extension 46 and the stem 48 and avoid jamming of the reversible poppet valve 40 around said stem.

The reversible poppet valve 40 may be made of any suitable rigid plastic material, such as polypropylene (PP) or ABS.

In accordance with the present invention, the upper edge (fixed valve seat) 22 of the central circular valve opening 20 is provided with an annular soft seat 50 having a thin annular cantilevered platform or lip 52 extending toward the center of the central circular valve opening 20.

The annular soft seat 50 with cantilevered lip 52 may be made of any suitable rubber material, such as Nitrile Butadiene Rubber (NBR), and is clamped to the fixed valve seat 22 of the valve housing 10 by means of a rigid ring 54.

In order to firmly fix the annular soft seat 50 to the (fixed valve seat) upper edge 22 of the central circular valve opening 20, the rigid ring 54 may be provided with downwardly extending flexible fingers 55 and at the lower ends of the flexible fingers locking claws 56 designed to catch onto the lower surface of the closing wall 21 of the valve housing 10.

In the normally closed position (fig. 1 and 2), the reversible poppet valve 40 is free to rest with its reverse angled conical surface 44 against the cantilevered lip 52 of the soft annular seat 50 which provides a reliable sealing surface under normal (balanced) air pressure conditions.

In the event of a sudden negative pressure within the sewer system, as shown in fig. 3 and 4, atmospheric pressure will raise the reversible poppet valve 40 and atmospheric air will be momentarily introduced into the sewer pipe. When the air pressure in the sewer system is balanced, the reversible poppet valve 40 will return to the closed position against the cantilevered lip 52 by gravity.

During the lifting of the movable closing part 24, the reversible poppet valve 40 will be guided by the tubular extension 46 to move on the fixed rod 48 and prevented from falling out by the central upper portion 28 of the reversible poppet valve 40 abutting against the lower surface of the upper cover 14 of the valve housing 10.

In the event of overpressure in the sewer system, the air contained in the interior space 19, the passageway 18 and the space 32 in the upper cover 14 will push against the central upper portion 28 of the reversible poppet valve 40 causing the reverse angled conical surface 44 to firmly press against the cantilever lip 52 deforming it downwardly while increasing the sealing surface due to the reverse angled conical surface 44. During this time it is clear that the larger the overpressure, the larger the sealing surface, thereby providing an enhanced sealing against the overpressure in the sewer system.

From the above description of the invention it is clear that a significant improvement has been obtained with respect to the prior art closing and sealing members in inlet valves used in sewer systems.

The main advantages of the invention with respect to known sealing devices are: the shape and assembly of the closing and sealing member is easy to manufacture while providing a more efficient lifting power of the poppet valve in case of sudden negative air pressure in the sewer system and an improved closing accuracy and sealing capability of the inlet valve both in equilibrium air pressure conditions in the sewer system and at any possible positive air pressure in the sewer system.

The embodiments described herein are intended to be illustrative only, and other modifications are possible within the scope of the invention as described in the following claims.

Description of reference numerals:

10: air inlet valve casing

12: tubular member

14: upper cover of shell

16: access to the surrounding atmosphere

18: access to the inner space of a sewer system

19: the inner space of the tubular member 12

20: valve opening with circular center

21: closing wall of the housing 10

22: fixed valve seat (sealing element)

24: movable closing part

26: lower surface of the closing member 24

28: center upper part (surface) of closing part 24

30: internal valve space connected to passageway 16

32: space within the cover 14 connected to the passageway 18

40: (reversible) poppet valve

42: inverted bowl shaped inner part (lower part of lift valve)

44: reverse angled conical surfaces

45: upper edge

46: tubular extension

48: fixed vertical rod

50: annular soft seat

52: cantilever lip

54: rigid ring

55: finger-shaped part

56: lock claw

Claims (15)

1. An air admission valve to be connected to a sanitary waste water pipe system for admitting atmospheric air into the waste water pipe system towards a valve sealing means in response to a sudden pressure drop in the waste water pipe system so as to protect a water trap in the waste water pipe system and prevent contaminated air from being discharged from the waste water pipe system to the atmosphere, the air admission valve comprising an air admission valve housing (10) comprising:

a vertical tubular member (12) connectable to the waste water pipe system and having an inner space (19);

a cap or cover (14) located at an upper end of the valve housing (10) and having an interior space (32);

a valve opening (20) between the vertical tubular member (12) and the cover (14) and a valve sealing arrangement comprising a fixed valve seat (22) co-operable with a movable closure member (24) at the periphery of the valve opening (20);

at least one passage (16) from an internal valve space (30) of the valve housing (10) to the surrounding atmosphere;

at least one passage (18) leading from an inner space (32) of the cap or cover inside the valve housing (10) to an inner space (19) of the vertical tubular piece;

said passages being in contact with an upper or lower surface, respectively, of said movable closing member (24) so as to lift said movable closing member (24) upon a sudden loss of air pressure in said waste water pipe system to allow fresh air to enter into said waste water pipe system via said passages (16) leading from an internal valve space (30) of said valve housing (10) to the ambient atmosphere in order to equalize the air pressure within said waste water pipe system,

the movable closing member (24) comprises a rigid movable member having the shape of a circular reversible poppet valve (40), said circular reversible poppet valve (40) being provided with a conical peripheral collar having an oppositely angled conical surface (44) extending upwards at an angle alpha, said circular reversible poppet valve being further provided with an inverted bowl-shaped interior (42), the central upper portion (28) of the inverted bowl-shaped interior extending at a level that is higher than the level of the upper peripheral edge (45) of the reverse angled conical surface (44), and the circular reversible poppet valve (40) cooperates with the fixed valve seat (22), the fixed valve seat (22) being provided with an annular soft seat (50), the annular soft seat has a thin annular cantilever platform or lip (52) extending toward the center of the valve opening (20).

2. An inlet valve according to claim 1, characterized in that the lower surface of the inverted bowl-shaped inner portion (42) is provided at its center with a tubular extension (46) designed for guiding purposes to cooperate with a vertical rod (48) rigidly connected to the closing wall (21) of the valve housing (10).

3. An inlet valve according to claim 2, characterized in that the vertical rod (48) is provided with a star-shaped outer surface in order to reduce friction between the tubular extension (46) of the circular reversible poppet valve (40) and the outer surface of the vertical rod (48).

4. An inlet valve according to claim 1, characterized in that the oppositely angled conical surface (44) of the conical peripheral collar extends upwards at an angle between 20 ° and 45 °.

5. An inlet valve according to claim 1, characterized in that the oppositely angled conical surface (44) of the conical peripheral collar extends upwards at an angle of 30 °.

6. An inlet valve according to claim 1, characterized in that the oppositely angled conical surface (44) of the conical peripheral collar extends upwards along an arc of a circle having a radius (R).

7. An inlet valve according to claim 6, characterized in that the radius (R) of the circular arc of the reverse angled conical surface (44) is equal to the diameter of the valve opening (20).

8. An inlet valve according to claim 1, characterized in that the circular reversible poppet valve (40) is made of a rigid plastic material.

9. An inlet valve according to claim 8, characterized in that the circular reversible poppet valve (40) is made of polypropylene (PP) or Acrylonitrile Butadiene Styrene (ABS).

10. An inlet valve according to claim 1, characterized in that the annular soft seat (50) is made of a rubber material.

11. An inlet valve according to claim 10, characterized in that the annular soft seat (50) is made of Nitrile Butadiene Rubber (NBR).

12. An inlet valve according to claim 1, characterized in that the soft annular seat (50) is clamped to the fixed valve seat (22) by means of a rigid ring (54) fixed to the valve housing (10).

13. An inlet valve according to claim 12, characterized in that the rigid ring (54) is clamped to the underside of the closing wall (21) of the valve housing (10) by means of a set of resilient locking claws (56) arranged at the lower extremities of fingers (55) extending downwards from the rigid ring (54).

14. An inlet valve according to claim 1, characterized in that the lower surface of the inverted bowl-shaped interior (42) of the circular reversible poppet valve (40) is in permanent contact with atmospheric pressure and the upper surface is in pressure contact with the interior space of the waste water piping system.

15. Method for closing and sealing an air admission valve according to any of claims 1 to 9, connected to a sanitary waste water pipe system and comprising a movable rigid closing member in the shape of a circular reversible poppet valve (40) and a fixed valve seat (22) with an annular soft seat (50), characterized in that,

-during an equilibrium or positive air pressure condition within the waste water pipe system, a movable circular reversible poppet valve (40) is brought into abutment against the valve seat (22) in a normal position,

-lifting the movable circular reversible poppet valve (40) from the valve seat (22) in case of underpressure in the waste water pipe system, improving the lifting force by the shape of the inverted bowl-shaped interior of the valve and being provided with oppositely angled conical surfaces (44) at its periphery, and limiting the upward movement of the circular poppet valve (40) due to the central upper part of the inverted bowl-shaped interior of the valve abutting against the lower surface of the cover (14) of the valve housing (10),

-in case of overpressure in the waste water pipe system, causing the movable circular reversible poppet valve (40) to be pressed down on the soft cantilevered edge of the soft annular seat (50) bending it down in order to increase the sealing surface between the movable circular reversible poppet valve (40) and the soft annular seat (50).