GB2170298A - Circular flap valve with buffer - Google Patents

Abstract

A flap valve, e.g. to prevent reverse flow of water into a pipeline, comprises an annular frame having a tubular extension (12) against which a door (14) rests in the closed position. The door is mounted by brackets (16, 18) through which pass a hinge pin (15). A resilient buffer (20) is retained by the hinge pin (15) and serves to prevent the door from opening beyond a predetermined distance. <IMAGE>

Description

SPECIFICATION Circular flap valve with buffer THIS INVENTION concerns a flap valve of the kind comprising a frame defining an opening, and a door attached by a hinge to the frame thus to be movable between positions in which it reveals and occludes said opening respectively.

Flap valves of this kind are commonly used to prevent reverse flow of water into a pipeline where the pipeline leads to, for example, a land drainage outfall, and are found on openings in head walls and in sewers.

The invention is particularly, though not exclusively, concerned with circular flap valves wherein the frame includes an annular flange for attachment to a flanged pipe end or to a head wall, a tubular extension projecting forwardly from the flange and presenting an inclined sealing face, and a generally circular door hingedly attached to the frame at a position thereon to be disposed uppermost in use, the door usually having a circular ring seal of a resilient material bonded to the rear face to provide an effective seal against the open end of the tubular portion.

A disadvantage found in the use of this kind of valve, is that under surge conditions the door is likely to open violently by an excessive amount, and in time this can lead to rapid wear of the hinge, and, in extreme cases, breakage of the door.

An object of the present invention is to provide a device which prevents the door from swinging excessively and controls the degree of permitted movement thereof.

According to the present invention there is provided a flap valve comprising a frame defining an opening, a door attached by a hinge to the frame thus to be movable between positions in which it reveals and occludes said opening respectively, characterised by a resilient buffer disposed adjacent said hinge thus to form a stop between the door and the frame and preventing opening of the door beyond a predetermined distance.

An embodiment of the invention will now be described, by way of example only, with reference to the accompanying drawings, in which: Figure 1 is a front elevation of a circular flap valve incorporating the invention; and Figure 2 is a vertical section taken on line Il-Il of Fig. 1.

Referring now to the drawings, the flap valve comprises a frame generally indicated at 10 preferably of a rigid plastics material and consisting of an annular flange 11 to which is integrally moulded a tubular extension 12 which projects forwardly from the flange 11.

The end of the tubular portion 12 remote from the flange 11 is finished to present an inclined sealing face 13.

A door 14 generally circular in shape is hingedly attached by a hinge pin 15 to flange 11 by a hinge bracket 16 bolted at 17 to the door, the pin 15 also passing through a pair of hinge projections 18 attached to or integrally moulded with flange 11.

A resilient ring 19 is bonded to the inner face of door 14 to provide a seal against the face 13, and to ensure quiet closing action.

In accordance with the invention, in order to prevent the door from swinging open excessively, a buffer 20 of a resilient material such as neoprene having, for example, a shore hardness of 50, is disposed between hinge bracket 16 and flange 11 thus to form a stop which limits opening of the door beyond a predetermined distance. Thus it can be seen that the door is prevented from opening beyond an angle of approximately 30 from its closed position. The buffer 20 is retained by hinge pin 15 which passes through an aperture in the buffer.

If a wider opening is required the upper part of the buffer 20 can be chamfered to prevent an inclined surface as indicated by dotted line 21.

The resilient nature of buffer 20 as well as sealing ring 19, ensures that the door, body and hinge assembly are protected against shock at the limits of the permitted door movement.

1. A flap valve comprising a frame defining an opening, a door attached by a hinge to the frame thus to be movable between positions in which it reveals and occludes said opening respectively, characterised by a resilient buffer disposed adjacent said hinge thus to form a stop between the door and the frame and preventing opening of the door beyond a predetermined distance.

2. A flap valve according to Claim 1, wherein said door is attached to the frame by a hinge pin which passes through brackets on the door and the frame respectively, the resilient buffer being disposed between said brackets, and retained by the hinge pin.

3. A flap valve according to Claim 1 or Claim 2, wherein said resilient buffer presents an inclined surface against which a part of the door bears to permit maximum opening of the door.

4. A flap valve according to any preceding claim in which said buffer is made from neoprene having a shore hardness at or in the region of 50.

5. A flap valve substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (5)

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION Circular flap valve with buffer THIS INVENTION concerns a flap valve of the kind comprising a frame defining an opening, and a door attached by a hinge to the frame thus to be movable between positions in which it reveals and occludes said opening respectively. Flap valves of this kind are commonly used to prevent reverse flow of water into a pipeline where the pipeline leads to, for example, a land drainage outfall, and are found on openings in head walls and in sewers. The invention is particularly, though not exclusively, concerned with circular flap valves wherein the frame includes an annular flange for attachment to a flanged pipe end or to a head wall, a tubular extension projecting forwardly from the flange and presenting an inclined sealing face, and a generally circular door hingedly attached to the frame at a position thereon to be disposed uppermost in use, the door usually having a circular ring seal of a resilient material bonded to the rear face to provide an effective seal against the open end of the tubular portion. A disadvantage found in the use of this kind of valve, is that under surge conditions the door is likely to open violently by an excessive amount, and in time this can lead to rapid wear of the hinge, and, in extreme cases, breakage of the door. An object of the present invention is to provide a device which prevents the door from swinging excessively and controls the degree of permitted movement thereof. According to the present invention there is provided a flap valve comprising a frame defining an opening, a door attached by a hinge to the frame thus to be movable between positions in which it reveals and occludes said opening respectively, characterised by a resilient buffer disposed adjacent said hinge thus to form a stop between the door and the frame and preventing opening of the door beyond a predetermined distance. An embodiment of the invention will now be described, by way of example only, with reference to the accompanying drawings, in which: Figure 1 is a front elevation of a circular flap valve incorporating the invention; and Figure 2 is a vertical section taken on line Il-Il of Fig. 1. Referring now to the drawings, the flap valve comprises a frame generally indicated at 10 preferably of a rigid plastics material and consisting of an annular flange 11 to which is integrally moulded a tubular extension 12 which projects forwardly from the flange 11. The end of the tubular portion 12 remote from the flange 11 is finished to present an inclined sealing face 13. A door 14 generally circular in shape is hingedly attached by a hinge pin 15 to flange 11 by a hinge bracket 16 bolted at 17 to the door, the pin 15 also passing through a pair of hinge projections 18 attached to or integrally moulded with flange 11. A resilient ring 19 is bonded to the inner face of door 14 to provide a seal against the face 13, and to ensure quiet closing action. In accordance with the invention, in order to prevent the door from swinging open excessively, a buffer 20 of a resilient material such as neoprene having, for example, a shore hardness of 50, is disposed between hinge bracket 16 and flange 11 thus to form a stop which limits opening of the door beyond a predetermined distance. Thus it can be seen that the door is prevented from opening beyond an angle of approximately 30 from its closed position. The buffer 20 is retained by hinge pin 15 which passes through an aperture in the buffer. If a wider opening is required the upper part of the buffer 20 can be chamfered to prevent an inclined surface as indicated by dotted line 21. The resilient nature of buffer 20 as well as sealing ring 19, ensures that the door, body and hinge assembly are protected against shock at the limits of the permitted door movement. CLAIMS

1. A flap valve comprising a frame defining an opening, a door attached by a hinge to the frame thus to be movable between positions in which it reveals and occludes said opening respectively, characterised by a resilient buffer disposed adjacent said hinge thus to form a stop between the door and the frame and preventing opening of the door beyond a predetermined distance.

2. A flap valve according to Claim 1, wherein said door is attached to the frame by a hinge pin which passes through brackets on the door and the frame respectively, the resilient buffer being disposed between said brackets, and retained by the hinge pin.

3. A flap valve according to Claim 1 or Claim 2, wherein said resilient buffer presents an inclined surface against which a part of the door bears to permit maximum opening of the door.

4. A flap valve according to any preceding claim in which said buffer is made from neoprene having a shore hardness at or in the region of 50.

5. A flap valve substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.