FIELD OF THE INVENTION

The invention relates to a check valve of the so-called “duckbill” type for use in drainage systems and effluent outfall lines. A typical duckbill check valve has an inlet, an outlet bill, and a transitional middle part for connecting the inlet and the outlet bill.

BACKGROUND OF THE INVENTION

Conventional rubber duckbill check valves may be symmetrical in two planes and attachable to the end of an outlet pipe. See, U.S. Pat. No. 4,607,663. Other duckbill check valves have been designed with horizontally orientated offset lips at the outlet bill. See U.S. Pat. No. 4,585,031. One drawback with this type of design is that water or other fluid may accumulate in the check valve due to the positioning and orientation of the lips at the outlet bill.

Additionally, some rubber duckbill check valves are not able to be utilized in every installation because of spatial problems. The duckbill check valve must have sufficient clearance between the end of the pipe and ground level for proper operation of the outlet bill. If this is not the case, for example, gravel, dirt or sand will accumulate around the lower portion of the outlet bill of the check valve, thereby preventing proper opening of the outlet bill.

U.S. Pat. No. 5,931,197 discloses a rubber duckbill check valve with vertically orientated lips at the outlet bill. The inside lower edge of the lower half of the transition portion of the check valve is at the same level as (aligned with) the inside lower edge of the inlet and the inside lower edge of the outlet bill, while the inside upper edge of the transition portion increases in size, from an axial center line, along a direction from the inlet to the outlet. While the design of the duckbill check valve in U.S. Pat. No. 5,931,197 presumably overcomes the spatial drawbacks associated with some installations, the use of a flat lower transition portion increases the potential for water to accumulate or retention within the pipe and the check valve instead of draining out of the check valve as desired.

It would be desirable to provide a duckbill check valve that is able to be used in installations with spatial clearance issues, and which reduces the accumulation of water or fluid within the check valve.

BRIEF SUMMARY OF THE PRESENT INVENTION

The present invention overcomes one or more drawbacks by providing a check valve with an inlet end, an outlet end, and a transition part connecting the inlet end with the outlet end. The check valve according to the present invention has a pair of vertically extending lips and is asymmetric about a horizontal longitudinal plane through the center of the inlet of the check valve. The inner surface on the upper portion of the transition part has an increasing size (measured from an axis through the center of the inlet of the check valve) along a direction of the axis from the inlet to the outlet, while the inner surface of the lower portion of the transition part also has an increasing size (along the same direction) but with a smaller rate of increase.

With the present check valve, it is thus possible to position the check valve in most any installation such that there is sufficient clearance below the bill of the valve and above ground level. Additionally, due to the orientation of the lips and the increasing size of the lower portion of the transition part, water (or other fluid) is less likely to accumulate within the check valve or associated piping, and instead is drained as desired.

Accordingly, in a first aspect the present invention may be characterized as providing a check valve which includes an inlet end, an outlet end, and, a transition part located between the inlet end and the outlet end. The check valve is asymmetrical about a horizontal longitudinal plane through the check valve, and the horizontal longitudinal plane is coincident with a center axis of the inlet end. The outlet end comprises a pair of vertically orientated lips. A difference between a first distance measured from the center axis to an inner surface of a lower portion of the outlet end and a second distance measured from the center axis to an inner surface of a lower portion of the inlet end is greater than zero.

It is contemplated that the check valve further includes a flange on the inlet end. A third distance, measured from the center axis to an outside bottom of the flange, may be greater than a fourth distance, measured from the center axis to an outside bottom of the outlet end.

It is also contemplated that the check valve further includes a cuff on the inlet end. The cuff may have an inner diameter greater than an inner diameter of the inlet end. A third distance, measured from the center axis to an outside bottom the cuff may be substantially the same size as a fourth distance, measured from the center axis to an outside bottom of the outlet end.

It is further contemplated that the transition part includes a support along an upper portion of the transition part. The support may be integrally formed with the check valve.

It is even further contemplated that the pair of vertically orientated lips have a variable rigidity along their height. An upper portion of the vertically orientated lips may be more rigid compared with a lower portion of the vertically orientated lips.

In another aspect, the present invention may be broadly characterized as providing a check valve that includes an inlet end, an outlet end, and a transition part located between the inlet end and the outlet end. The check valve is asymmetrical about a horizontal longitudinal plane through the check valve, with the horizontal longitudinal plane being coincident with a center axis of the inlet end. The outlet end comprises a pair of vertically orientated lips. The transition part comprises an increasing size along its length, from the inlet end to the outlet end. A distance from the center axis to an inner surface of an upper portion of the transition part increases, in a direction from the inlet end to the outlet end, at a greater rate than a distance from the center axis to an inner surface of a lower portion of the transition part.

It is contemplated that the check valve includes a flange on the inlet end. A third distance, measured from the center axis to an outside bottom of the flange, may be greater than a fourth distance, measured from the center axis to an outside bottom of the outlet end.

It is further contemplated that the check valve includes a cuff on the inlet end, the cuff having an inner diameter greater than an inner diameter of the inlet end. A third distance, measured from the center axis to a bottom of the cuff may be substantially the same size as a fourth distance, measured from the center axis to a bottom of the outlet end.

It is still further contemplated the transition part includes a support along an upper portion of the transition part.

It is also contemplated that the pair of vertically orientated lips have a variable rigidity along their height.

In a third aspect of the present invention, the present invention may be generally characterized as providing a check valve which includes an inlet end, an outlet end, and a transition part located between the inlet end and the outlet end. The check valve is asymmetrical about a horizontal longitudinal plane through the check valve, and the horizontal longitudinal plane is coincident with a center axis of the inlet end. The outlet end comprises a pair of vertically orientated lips. The transition part comprises an increasing size along its length, from the inlet end to the outlet end. A slope of a line along an inner surface of an upper portion of the transition part is greater than an absolute value of a slope of a line along an inner surface of a lower portion of the transition part. The slope of the line along the inner surface of the lower portion of the transition part is not zero.

It is contemplated that the check valve further includes a flange on the inlet end, and a third distance, measured from the center axis to a bottom of the flange, is greater than a fourth distance, measured from the center axis to a bottom of the outlet end.

It is further contemplated that the check valve includes a cuff on the inlet end, and the cuff has a diameter greater than a diameter of the inlet end. A third distance, measured from the center axis to a bottom of the cuff is substantially the same size as a fourth distance, measured from the center axis to a bottom of the outlet end.

It is also contemplated that the pair of vertically orientated lips have a variable rigidity along their height.

These and other aspects and embodiments of the present invention, which may be combinable in any aspect or manner, will be appreciated by those of ordinary skill in the art based upon the following description of the drawings and detailed description of the preferred embodiments.

