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

Patent metadata

Field	Value
Publication number	US-9517751-B2
Application number	US-201414332601-A
Country	US
Kind code	B2
Filing date	Jul 16, 2014
Priority date	May 23, 2014
Publication date	Dec 13, 2016
Grant date	Dec 13, 2016

Abstract

A wiper arm assembly has a load member, a wiper arm, and a blade load cam with a cam slot. The load member mates with a joint disposed between first and second ends of the wiper arm. Changes in length of the load member impose a force in a lengthwise direction of the load member. The wiper arm is configured to rotate relative to the blade load cam about an axis proximate to the first end of the wiper arm. The cam slot is configured to vary the length of the load member as a function of a wiper angle in which the wiper angle is defined as the angle between the wiper arm and a starting position of the wiper arm.

First claim

The invention claimed is:

1. 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; and
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;
wherein the cam slot comprises:
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.

2. The wiper arm assembly of claim 1 , wherein the cam slot has a curved path that is generally concave toward the axis of the blade load cam.

3. The wiper arm assembly of claim 1 , wherein the second end of the wiper arm connects to a blade that contacts a surface, and wherein the wiper arm assembly is configured such that the load member causes the blade to impose a blade load on the surface.

4. The wiper arm assembly of claim 3 , wherein a radially outward portion of the cam slot with respect to the axis of the blade load cam corresponds to a wiper angle range through which the blade traverses a discontinuity on the surface.

5. The wiper arm assembly of claim 1 , further comprising:
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; and
a cam follower that mates with the second end of the load member and the cam slot.

6. The wiper arm assembly of claim 5 , wherein the cam follower is substantially co-linear with the load member.

7. The wiper arm assembly of claim 5 , the arm hub further comprising:
a first protrusion, and
a second protrusion offset from the first protrusion, wherein the first and second protrusion restrain the cam follower such that the cam follower is co-planar with a plane defined by the axis of the blade load cam and the joint of the wiper arm.

8. The wiper arm assembly of claim 5 , further comprising:
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.

9. The wiper arm assembly of claim 1 , wherein the cam slot is defined by a first radius corresponding to the starting position of the wiper arm, a second radius corresponding an extending position of the wiper arm, and a third radius between the first and second radii along the cam slot, each radius being defined between the axis and the cam slot, and wherein the third radius is greater than the first and second radii.

10. The wiper arm assembly of claim 9 , wherein the second end of the wiper arm connects to a blade that contacts a surface, and wherein the third radius corresponds to a region of high curvature of the surface.

11. The wiper assembly of claim 9 , wherein the second end of the wiper arm connects to a blade that contacts a surface, and wherein the third radius corresponds to a boundary of the surface where the blade traverses from the surface to an adjacent surface.

12. The wiper assembly of claim 1 , wherein the cam slot is defined by a first radius corresponding to the starting position of the wiper arm in which the wiper arm is orientated substantially parallel to a direction of air flow local to the wiper arm and a second radius corresponding an extended position of the wiper arm, each radius being defined between the axis and the cam slot, and wherein the second radius is greater than the first radius such that the load member lengthens as the wiper arm transverses from the starting position to the extended position.

13. 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.

14. The method of claim 13 , wherein the cam slot is configured to reduce the blade load of a wiper angle range through which the blade traverses a discontinuity in the surface.

15. The method of claim 13 , wherein the cam slot is configured to increase the blade load of a wiper angle range through which aerodynamic forces on the wiper blade tend to decrease the blade load.

16. 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

Assignees

• Rosemount Aerospace Inc
• Rosemount Aerospace

Inventors

• Reid Alexander N
• Webb Matthew

Classifications

• B60S1/3468

  Mountings therefor · CPC title

• Y10T29/49828

  Progressively advancing of work assembly station or assembled portion of work · CPC title

• B60S1/3411 Primary

  with means for varying wiper-blade pressure on windshield during operation · CPC title

• B60S1/34 Primary

  Wiper arms; Mountings therefor {(wiper arms provided with liquid spreading means B60S1/522; with gas spreading means B60S1/544)} · CPC title