| 摘要 |
The pump drive mechanism is driven by a wiper drive motor having a drive pin adapted to revolve in a circular path, while driving the wipers, and which is displaced along a generally radially directed path outwardly of the circular path, at a prescribed point thereon, when the wipers are moved to the park position. The mechanism has a rotatable drive cam, which is connected, via a cam follower, to reciprocate the piston rod of the pump. To facilitate installation, the drive cam carries a drive pin engaging portion designed to automatically engage the drive pin, after the first actuation of the wiper motor, regardless of the initial relative positions of the drive pin and drive cam. As a result, the necessity for positioning the drive cam with respect to the drive pin in a prescribed position during installation is eliminated. A second aspect of the invention relates to the pump action termination portion of the mechamism which includes an indexable rachet wheel having evenly spaced, uniformly shaped teeth, provided to count a given number of strokes. After the given number of strokes, a substantially wedge shaped cam, carried on the rachet wheel, is moved into position as the wheel is indexed, to engage a lip on the reciprocating piston rod to prevent further pump actuation. The structure of the cam and lateral movement of the piston rod permit same to cooperate in a manner which facilitates positioning of the lip relative to the cam, thereby eliminating the necessity for the presence of a flexible tooth on the rachet wheel, heretofore required to permit sufficient "yield" in the mechanism to prevent binding of the cam and lip.
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