Windshield wiper system with blade assembly drive for maintaining a constant attack angle of the wiper blade on a curved a windshield

Windshield wiper system for vehicles with a windshield having a curved surface, comprising:

• at least one elongated wiper arm mounted for oscillation about an oscillatory axis and having a free end;
• an elongated wiper blade assembly defining a longitudinal axis, said wiper blade assembly being pivotally mounted on said free end of said wiper arm about an axis parallel to said longitudinal axis;
• an oscillating drive for oscillating said wiper arm about said oscillatory axis across the windshield;
• a shaft disposed on said free end of said wiper arm, said shaft defining a longitudinal shaft axis extending parallel to said oscillatory axis, said wiper blade assembly being coupled to said shaft;
• and
• pivot drive means connected to said wiper blade assembly for driving said wiper blade assembly about said axis parallel to said longitudinal axis as a function of an oscillatory position of said wiper arm;
• said pivot drive means including a cam with a cam surface pivotally disposed on said shaft and cam follower means disposed on said wiper blade assembly, said cam surface riding on said cam follower means for pivoting said wiper blade assembly about said axis parallel to said longitudinal axis relative to said wiper arm and for maintaining a substantially constant attack angle of said wiper blade assembly relative to the windshield during the oscillatory movement of said wiper arm.