| 摘要 |
A fluid coupling device is disclosed of the type including an output coupling (13) and an input coupling member (11). The speed of operation of the coupling device is determined by the amount of fluid in the operating chamber (37), and fluid communication from the reservoir chamber (41) into the operating chamber is controlled by movement of a valve arm (49) relative to a fill opening (50). The fill opening includes an outer edge (79) which is disposed at an angle relative to a radial line, such that the valving is of the modulating type, i.e., movement of the valve arm in response to increasing temperature results in radially outward movement of the outermost point of the flow area. In accordance with the invention, the valve arm defines an included open area (73) having a leading edge (74) and a trailing edge (75). The flow area is determined by the area of overlap (77,81) of the open area (73) and the fill opening (50). The result is a modulating but limited area which is effective to substantially reduce hysteresis of the coupling device during operation in the decreasing temperature condition, whereby the input horsepower consumed by the device is substantially reduced.
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