Mechanism for dynamically varying blade load over a windshield wiper sweep cycle

A method of varying a blade load of a wiper arm assembly, the method comprising:

• providing a load member having a first end and a second end spaced in a lengthwise direction from the first end, wherein changes in length of the load member impose a force in the lengthwise direction of the load member;
• providing a wiper arm having a first end, a second end opposite the first end, and a joint disposed between the first and second ends, wherein the joint is configured to mate with the load member;
• providing a blade configured to mate with the second end of the wiper arm, wherein the force transmitted through the load member causes the blade to contact a surface with a blade load;
• providing a blade load cam having a cam slot and an axis proximate to the first end of the wiper arm, wherein the wiper arm is configured to rotate relative to the blade load cam about the axis;
• configuring the cam slot to vary the length of the load member as a function of a wiper angle defined as the angle between the wiper arm and a starting position of the wiper arm, wherein the cam slot has an inner face inclined with respect to the axis of the blade load cam such that an acute angle is formed between the inner face and the axis of the blade load cam in a radial cross section passing through the axis of the blade load cam and intersecting the cam slot;
• providing a cam follower that mates with the second end of the load member and the cam slot;
• configuring the cam slot to vary the blade load;
• and
• actuating the wiper arm assembly such that the wiper arm and the blade oscillate about the axis proximate to the first end of the wiper arm, wherein the blade load varies via the cam slot changing the length of the load member.

A wiper arm assembly comprising:

• a load member having a first end and a second end spaced in a lengthwise direction from the first end, wherein changes in length of the load member impose a force in the lengthwise direction of the load member;
• a wiper arm having a first end, a second end opposite the first end, and a joint disposed between the first and second ends, wherein the joint is configured to mate with the load member;
• a blade load cam having a cam slot and an axis proximate to the first end of the wiper arm, wherein the wiper arm is configured to rotate relative to the blade load cam about the axis, and wherein the cam slot is configured to vary the length of the load member as a function of a wiper angle defined as the angle between the wiper arm and a starting position of the wiper arm;
• an arm hub configured to mate with an output shaft of an actuator, wherein the arm hub mates with the wiper arm at a pin attachment;
• a cam follower that mates with the second end of the load member and the cam slot;
• a converter enclosed within a housing, wherein the converter transforms a rotatory input into an oscillatory output;
• an output sleeve defined by a cylindrical structure extending from the housing, wherein the blade load cam is affixed to the output sleeve;
• and
• an output shaft disposed concentrically within the output sleeve, wherein the output shaft mates with the arm hub, and wherein the output shaft transmits the oscillatory output of the converter to the arm hub.