Ventilation – Vehicle – Having outlet airway
Reexamination Certificate
1999-03-15
2001-04-03
Joyce, Harold (Department: 3749)
Ventilation
Vehicle
Having outlet airway
C137S855000
Reexamination Certificate
active
06210266
ABSTRACT:
FIELD OF THE INVENTION
This invention relates generally to one-way pressure relief valves, and in particular to such a valve for use in conjunction with a ventilation system for a passenger compartment of an automotive vehicle.
BACKGROUND OF THE INVENTION
One-way, flap-type pressure relief valves are commonly used in applications such as vehicle ventilation systems. Typically, the valve serve to relieve over-pressure that can occur within a nearly air-tight passenger compartment of a vehicle when, for example, a door of the vehicle is rapidly closed, while preventing the entry of air from outside the vehicle into the passenger compartment.
Valves used for this purpose generally include a frame or housing for mounting within an aperture formed in a panel enclosing the passenger compartment and defining an air passageway through the panel. The housing has one or more internal valve seats over which a plurality of valve flaps lie. The flaps include relatively thin, flexible members and overlie the valve seats on a side of the housing facing exterior of the passenger compartment. Each flap is fixed to the housing along one peripheral edge.
When an over-pressure condition occurs within the passenger compartment, the air pressure forces the flaps to move away from the valve seats, bending or hinging adjacent the fixed edge to allow air to flow through the air passageway out of the passenger compartment. When the air pressure has equalized on both sides of the valve or when the pressure on the exterior becomes greater, the flaps swing or bend back to engage the valve seats and block airflow into the passenger compartment.
Valves of this general type are often manufactured by injection molding the housing and the valve flaps as separate pieces and then joining the two components by any one of several different methods. U.S. Pat. No. 5,601,117 teaches that apertures formed along an edge of the flap are placed over pins projecting from the corresponding portion of the housing. The ends of the pins are then flattened to form locking caps which secure the flap over the pin. U.S. Pat. No. 5,419,739 discloses a valve flap in the form of a flexible sheet having integrally formed tabs which are forced through respective slots formed in the housing. Each of these various methods of construction has inherent disadvantages, generally related to the fact that producing separate components that must be assembled with one another is time consuming and/or labor intensive, thus making the valve relatively expensive to manufacture.
U.S. Pat. No. 5,355,910 discloses a valve having a flap element formed by extruding a sheet of relatively soft, flexible elastomeric material, and simultaneously extruding one or more strips of relatively rigid plastic onto the surface of the sheet. A first of the strips provides a rigid mounting strip for bolting or otherwise joining the valve element to an associated valve housing. A second of the rigid strips can be formed to extend across the width of the flap adjacent the opposite edge thereof to prevent the valve element from warping or deforming during use. The gap between the mounting strip and the stiffening strip forms a flexible hinge where the flap bends to move between closed and open positions. The continuous extrusion is sheared to the length required for use in a valve assembly, and apertures are formed through the mounting strip so that the flap can be secured to the valve housing.
The extrusion technique requires the rigid strip to extend the full width of the flexible sheet and be a constant thickness and height. The extrusion technique is also unable to produce a plurality of flaps joined together in a top-to-bottom arrangement so that the flaps can then be attached to the valve housing in a single assembly step.
SUMMARY OF THE INVENTION
The present invention provides a valve flap assembly for use with a pressure relief valve which is efficiently and inexpensively produced by a co-molding operation and retains a flexible flap within a rigid frame for attachment to a valve housing. The invention further provides a flap structure that is sufficiently stiff to maintain a desired shape during use.
In accordance with one aspect of the invention, a valve flap assembly includes a relatively rigid flap carrier frame having a plurality of perimeter walls and a relatively flexible flap co-molded into connection with a first perimeter wall of the frame. The flap is joined to the perimeter wall along a hinge edge and is sufficiently flexible to bend about a line adjacent the hinge edge. The resulting flap assembly can be easily connected with a valve housing defining at least one air passage by securing the flap carrier frame to the housing such that a frame surrounds the passage, thus positioning the flap over a valve seat surrounding the passage.
According to a further aspect of the invention, the flap is co-molded into connection with the flap carrier frame in a configuration such that when the flap carrier frame is secured to the housing to position the flap over the air passage, the flap is bent away from the as-molded configuration as the flap comes into contact with the valve seats. This bending generates an elastic force urging the flap toward the valve seat in order to help to ensure that the valve flap closes completely and positively when pressure across the valve has equalized.
In accordance with another feature of the invention, the valve flap assembly includes first and second flaps co-molded into connection with respective first and second perimeter walls of the frame. The first and second walls are parallel with one another so that the frame can be secured to the valve housing to position the flaps over adjacent air passages of the housing. This provides a multi-flap assembly that can be attached to the valve housing as a single unit, thereby reducing manufacturing cost and complexity.
In accordance with a further aspect of the invention, at least one of the flexible flaps has stiffeners co-molded into connection therewith. The stiffeners are preferably formed simultaneously with the flap carrier frame in the first shot of the co-molding process, and the flap is subsequently molded so as to contact and be joined to the stiffener as well as the frame. Each of the stiffeners preferably includes an elongated first segment extending generally parallel to the hinge edge of the flap, and a second segment extending generally perpendicular to the first segment. This construction allows stiffening material to be added to the otherwise flexible flap only in the locations necessary, thus saving material and cost while achieving the desired flap stiffness.
In the embodiment of the flap valve assembly depicted herein, the flap carrier frame is molded to include a plurality of bosses extending therefrom which are inserted through apertures formed in the valve housing. The ends of the bosses distal from the flap carrier may then be flared outwardly by a heat staking process to retain the flap carrier in connection with the housing.
According to another aspect of the invention, a method is provided for producing a valve flap assembly for use in a pressure relief valve, the method including a two-shot co-molding process wherein the first shot forms a flap carrier frame from a relatively rigid plastic material, and the second shot forms a flap from a relatively flexible plastic material such that an edge of the flap is joined to the frame along a first perimeter wall of the frame. The use of the co-molding process allows formation of a flap carrier having a substantially continuous perimeter such that the flap can be molded substantially within the perimeter of the frame, and the frame can then be secured to a valve housing to surround an air passage and locate the flap over the passage.
In the preferred embodiment of the method, two flaps are formed by the second shot, one of the flaps attached to each of two parallel perimeter walls of the frame. The resulting flap assembly formed by this method is a unitary, multi-flap assembly which can be joined to a valve housi
Joyce Harold
Sarnamotive Blue Water, Inc.
Young & Basile P.C.
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