BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a schematic view of an exhaust valve assembly incorporating the subject invention.
FIG. 2 is a schematic side view of the exhaust valve assembly of FIG. 1 in an open position.
FIG. 3 is a schematic side view of the exhaust valve assembly of FIG. 1 in a closed position.
FIG. 4 is a schematic side view of the exhaust valve assembly moved from the closed position of FIG. 3 to an open position.
FIG. 5 is a schematic side view of the exhaust valve assembly moved from the open position of FIG. 4 to a closed position.
FIG. 6 is a schematic side view of the exhaust valve assembly moved from the closed position of FIG. 5 to an open position.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
An exhaust valve assembly is shown generally at 10 in FIG. 1. The exhaust valve assembly 10 includes a valve housing 12, a flapper valve 14, and a shaft 16, that is supported by at least one bearing 18 for rotation relative to the valve housing 12. The shaft 16 defines an axis of rotation 20. The flapper valve 14 is fixed to the shaft 16 and rotates with the shaft 16 about the axis of rotation 20.
The valve housing 12 includes a valve portion 12a and a shaft portion 12b. The valve portion 12a includes an inner cavity 22 that receives the flapper valve 14. The inner cavity 22 is defined by an inner diameter D1. The flapper valve 14 comprises a disc-shaped body that is defined by a maximum flapper diameter D2 that is less than the inner diameter D1.
The shaft 16 is coupled to an actuator that comprises a unidirectional drive unit 24. The unidirectional drive unit 24 rotates the shaft 16 and flapper valve 14 in only one direction about the axis of rotation 20 between open and closed positions to vary exhaust flow. A controller 26 generates control signals to the unidirectional drive unit 24 to move the flapper valve 14 between the open and closed positions as needed. In the example shown, the unidirectional drive unit 24 comprises a gear driven direct current (DC) motor.
FIG. 2 shows the flapper valve 14 in an open position where the disc-shaped body is generally orientated in a position that is parallel to exhaust flow through the valve housing 12. In the example shown, this initial open position is defined as a zero degree position, however, the flapper valve 14 could be angled slightly above or below zero degrees in the open position.
To move the flapper valve 14 from this initial open position to a closed position (FIG. 3), the unidirectional drive unit 24 rotates the shaft 16 and the flapper valve 14 in only one direction about the axis of rotation 20. In the example shown, the unidirectional drive unit 24 rotates the flapper valve 14 in a counter-clockwise direction about the axis of rotation 20 as indicated by arrow 30, however, the flapper valve could also be rotated in the opposite direction. In the closed position, the flapper valve 14 has been rotated approximately ninety degrees such that the disc-shaped body is generally perpendicular to the exhaust flow. Because the maximum flapper diameter D2 is less than the inner diameter D1 of the valve housing 12, the flapper valve 14 does not contact the valve housing 12. It should be understood that while a perpendicular orientation, i.e. a ninety degree rotation, is shown in FIG. 3, the flapper valve 14 could be rotated slightly more or less than ninety degrees to move into the closed position.
To move from the closed position in FIG. 3 to a subsequent open position as shown in FIG. 4, the unidirectional drive unit 24 rotates the flapper valve 14 in the same direction about the axis of rotation 20, i.e. a counter-clockwise direction, by approximately ninety degrees. As such, the flapper valve 14 has been rotated a total of one hundred and eighty degrees from the initial open position to a subsequent open position, as indicated by arrow 32.
To move from the subsequent open position in FIG. 4 to a subsequent closed position in FIG. 5, the unidirectional drive unit 24 rotates the flapper valve 14 again in a counter-clockwise direction about the axis of rotation 20 by approximately ninety degrees. As such, the flapper valve 14 has been rotated a total of two hundred and seventy degrees from the initial open position (FIG. 2) to a second closed position as indicated by arrow 34.
Finally, to rotate the flapper valve back to an open position (FIG. 6) from the closed position in FIG. 5, the unidirectional drive unit 24 rotates the flapper valve 14 another approximately ninety degrees about the axis of rotation 20. Thus, the flapper valve 14 has been rotated three hundred and sixty degrees about the axis of rotation 20, as indicated by arrow 36, to move from the open position shown in FIG. 2, through the positions shown in FIGS. 3-5, and back to the open position shown in FIG. 6.
The unidirectional drive unit 24 continues to drive the flapper valve 14 between open and closed positions by rotating the flapper valve in only one direction about the axis of rotation 20. By rotating the flapper valve 14 in only one direction about the axis of rotation 20, bearing life is improved and controls for the actuator are significantly simplified.
Although a preferred embodiment of this invention has been disclosed, a worker of ordinary skill in this art would recognize that certain modifications would come within the scope of this invention. For that reason, the following claims should be studied to determine the true scope and content of this invention.
Patent Application
20080034743
