Variable gap between HVAC door and sealing surfaces

A plenum assembly for carrying air in a supply system includes a duct including an opening formed with an inner surface through which air can flow; a door supported for movement between multiple positions which distributes air to the desired output path; and a seal secured to the door. In a vehicles HVAC system, numerous doors are utilized to provide comfort to the passengers based upon user input. The potential exists that some positions of the doors my lead to unwanted noise. A modification to the seal of the door with variable gap widths alleviates this issue and improves satisfaction.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates generally to an apparatus for opening and closing connections among passages that carry air in a heating, ventilation and air conditioning (HVAC) plenum.

2. Description of the Prior Art

A plenum assembly for carrying air in a supply system includes a duct with an inner surface through which air can flow and a door supported for movement between a multitude of open positions, at which flow through the opening is relatively unobstructed, and a sealed position, at which flow through the opening is relatively obstructed. Some positions of the door produce a small gap between the seal and the inner duct surface. The present invention includes a modification to the seal in which this gap has a continuously variable width along at least a portion of a length of the seal.

The variable edge profile provides a gap having a variable width and prevents uniform airflow over the seal. As a result, objectionable high frequency tones and whistles are prevented without compromising the functionality of the seal.

A need exists in the industry for a technique that prevents objectionable noise when the door moves near the sealed position.

SUMMARY OF THE INVENTION

A plenum assembly for carrying air in a supply system includes a duct including an opening formed with a inner surface through which air can flow; a duct including an opening formed with a inner surface through which air can flow; a door supported for movement between a sealed position, at which flow through the opening is relatively unobstructed, and a partially sealed position, at which flow through the opening is relatively obstructed; and a seal secured to the door and producing in the partially sealed position a gap between the seal and the inner surface, the gap having a continuously variable width along at least a portion of a length of the seal.

The variable edge profile on the edge of overmold door seals provides a gap having a variable width and prevents uniform airflow over the seal. As a result, objectionable high frequency tones and whistles are prevented without compromising the functionality of the seal.

DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring now to the drawings, there is illustrated inFIG. 1a plenum assembly that includes a duct12, which carries air in a HVAC system for an automotive application. The duct12has been cross sectioned by a transverse plane normal to the length of the duct. An inner surface14and an outer surface16of the duct12are formed with substantially flat surfaces, along which air flows longitudinally in the duct.

A door assembly includes two doors18,19, supported on a shaft20, which rotates about an axis22. Each door18,19rotates with shaft20to a respective sealed position, the sealed position of each door being located at an end of the door's rotary travel. The doors18,19direct air in the duct to selected paths, through which air is delivered from the duct to the passenger compartment of the vehicle.

The doors18,19are preferably formed of a rigid material, while the seal surrounding and secured to the periphery26of the door18,19is preferably formed of a relatively soft thermoplastic. This variable design may also be added to the perimeter of a door which does not utilize a thermoplastic seal.

FIG. 1shows shaft20having been rotated about axis22to the sealed position of door18, at which the door18and seal24substantially obstruct and prevent air flow in duct18past the seal and door.

When shaft20rotates about axis22in either rotary direction to a position at which door18and seal24are spaced angularly about five degrees from the duct opening, the door and seal are in a partially sealed position. When the door18and seal24are in the partially sealed position, air can flow in duct12through a small gap28between the duct's inner surface14and the seal's periphery30. In the partially sealed position, air flow past the seal24is partially obstructed, but air flow is substantially greater compared to any flow that may occur past seal24when door18and seal24are in their sealed position.

Similarly, shaft20can rotate doors18,19about 100 degrees away from the sealed position of door18to the sealed position of door19, at which door19and seal24substantially obstruct and prevent air flow in duct18past door19and seal24.

When shaft20rotates about axis22in either rotary direction to a position at which door19and seal24are spaced angularly about five degrees from the duct opening, door19and seal24are in their partially sealed position. When door19and seal24are in their partially sealed position, air can flow in duct12through a small gap between the duct's inner surface14and the seal's periphery30. In the partially sealed position, air flow past the seal24is partially obstructed but air flow is substantially greater compared to any flow that may occur when door19and seal24are in their sealed position.

FIG. 2is side view showing door18in its partially sealed position, i.e., spaced a short distance from the inner surface14of duct12, and door19in its sealed position contacting surface14.FIG. 3is a side view showing door18in its sealed position, i.e., contacting the inner surface14of duct12, and door19in its partially sealed position, spaced a short distance from the inner surface14.

In a first embodiment, the seal's periphery30is a continuous series of arcuate segments or angular projections forming a border of serrations, preferably a series of ridges32and grooves34along the peripheral length of the seal24and extending across the thickness36of the seal24, as shown inFIG. 2. Preferably the distance between consecutive ridges32and grooves34is random and non-uniform along the peripheral length of the seal24, although that spacing may be uniform. Similarly, the height of the ridges32and the depth of the grooves34are preferably random, although those heights and depths may be uniform along the peripheral length of the seal24.

FIGS. 2,3,4and5show that the right-hand side of shaft20is formed with external teeth42, and the left-hand side is formed with internal teeth40, and the back of door18, which faces downstream, is supported by a series of stiffeners44,46,48, spaced mutually across the width of the door.

In the embodiment ofFIGS. 1-5, the serration formed by the ridges32and grooves34causes the gap28between the seal's periphery30and the duct's inside surface14to be non-uniform along the peripheral length of the seal24. The variable profile of the gap28prevents uniform airflow across the seal's thickness36and along the peripheral length of the seal24. As a result, objectionable high frequency tones and whistles are prevented without compromising the functionality of the seal.

In the second embodiment shown inFIG. 6, the edge50of a door52is formed with a continuous series of arcuate segments or projections forming serrations, preferably a series of ridges54and grooves56. A seal58formed of relatively soft, vulcanized thermoplastic surrounding and secured to the door's edge50, has a uniform width60and straight sides before being installed on the door's edge50. Upon installation, the seal's periphery62conforms to the contour of the door's edge50. A gap64between the inner surface14of the duct12and the seal's periphery62is a continuous series of arcuate segments or projections forming serrations, preferably a series of ridges and grooves similar to those on the door's edge50. Preferably the width of gap64is random and non-uniform along the peripheral length of the seal58. This embodiment may also be utilized where the edge50of a door52does not have a seal attached, but has a series of ridges54and grooves56, which eliminate the uniformity of air passing by.

The door58is supported on shaft20and rotates with the shaft about axis22to the sealed and partially sealed positions. The door52is preferably formed of a rigid, polypropylene plastic containing mica.

Serrations formed by the ridges54and groove56cause the gap64between the seal's periphery62and the inner surface14of duct12to be non-uniform along the length of the seal. The variable width of gap64prevents uniform airflow across the seal's thickness36and along the peripheral length of the seal58. Objectionable high frequency tones and whistles are prevented without compromising the function of the seal58.

In the third embodiment shown inFIG. 7, the inner surface60of the duct62is formed with a continuous series of arcuate segments or projections forming serrations, preferably a series of ridges64and grooves66. A seal68, formed of relatively soft, vulcanized thermoplastic surrounding and secured to the straight outer edge70of the door72, has a straight outer edge74, which extends along the peripheral length of the seal.

The width of the gap74between the inner surface60of the duct62and the seal's periphery76is continuously variable along the peripheral length of the seal68. The variable width of gap64prevents uniform airflow across the seal's thickness36and along the peripheral length of the seal68. As a result, objectionable high frequency tones and whistles are prevented without compromising the function of the seal68.

The door18,52,72may rotate about axis22, which may be located and directed such that the door pivots to the sealed position downward from above the door or upward from below the door, as shown inFIGS. 1-5, or leftward or rightward. Alternately, the door may slide on a rail or in a track between the sealed and partially sealed positions.