Windshield wiper blade assembly with elastic cushion joint for allowing spring-resistance rotation of wiper blade relative to windshield surface

An improved windshield wiper blade assembly is disclosed. The improvement is comprised of the ability of the device to allow a controlled and virtually noise free rotation of the blade with respect to the long axis of the blade. The center of such rotation is not critical but it has been found to be most effective to allow the structure to pivot at the joint of the primary yoke and the secondary yoke of the wiper assembly. In doing so, the wiper blade is allowed to be pulled across the windshield surface and not pushed into the windshield thus increasing the wear life and wiping efficiency of the blade. A spring device is disclosed that causes this device to be center seeking to an angle of perpendicular to the surface of the windshield, thereby allowing rotation in a controlled manner. This provides movement in both directions of the reciprocating blade without excessive clearance holes that can cause a noisy operation, the result being a device that is more useful and less distractive to the operator of the vehicle utilizing the invention.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The invention disclosed herein relates to an improved windshield wiper 
assembly and specifically to a wiper assembly which permits the rotation 
of the blade in accordance with the direction of movement of the assembly 
with respect to the windshield, thus increasing the life of the blade and 
the effectiveness of same. 
2. Overview of Prior Art 
Since the invention of the automobile windshield, the difficulty of keeping 
it clean has challenged inventors and engineers. The windshield is of 
little use if the driver cannot see through it. Even minimal obstructions 
such as streaks and smears from inadequate wiper blades can result in 
detrimental and even potentially fatal consequences. The problem with most 
wiper blades is that they are not used for a long period of time and then 
when they are needed, they are necessary immediately. For this reason the 
process of improving the effectiveness and life of the blade is of valued 
importance. Many attempts have been made to try to accomplish this but 
have met with only limited success. Many times other problems have been 
created in the process. 
Allowing the blade to rotate axially along the long axis of the blade 
allows the cleaning edge of the blade to be pulled across the surface 
instead of pushed. Methods to accomplish this have been disclosed by Cayan 
in U.S. Pat. No. 5,325,563 and von Meltzing et. al. in U.S. Pat. No. 
5,033,157 in which complicated mechanisms and complex part assemblies are 
used. 
These are not only unusually expensive to produce and therefore potentially 
price themselves out of the market, but the added assembly and small 
components create a potential for premature deterioration of the 
structure. 
Speth and Quinian et. al. in U.S. Pat. Nos. 4,287,634 and 3,751,754 
respectively disclosed similar methods of allowing the blade to rotate 
along the long axis of the blade. Both provide a pin which extends through 
an oversized slot. The pin allows axial movement until the pin contacts 
the edge of the slot, thus halting the movement. The necessity of 
excessive clearance between moving parts of a device open to the 
environment is a potential for disaster as liar as debris clogging up the 
mating components and preventing movement. When this happens the device 
ceases to function in the desired manner. In addition, the constant 
"clinking" of the pin against the slot edge every time the wiper blade 
changes direction is enough to cause the driver and any passengers sitting 
nearby great irritation. No spring mechanism is used to cause the device 
to seek a center position perpendicular to the windshield position. This 
could accomplish the same thing without the sloppy clinking of metal pans. 
In U.S. Pat. No. 3,006,014, Krohm disclosed a rotating device that is set 
on an angle to the wiper arm and does allow for rotation along the long 
axis of the blade. The purpose is to allow the blade to remain 
perpendicular to the curved windshield. Though a potentially superior 
bearing surface is provided as compared to the previously mentioned two 
patents, the device also does not provide a spring mechanism and therefore 
the device will operate in a loose and sloppy manner, irritating to the 
operator of the vehicle on which the device is being used. 
A more complicated version of the devices previously mentioned is disclosed 
by Zaiger in U.S. Pat. No. 2,942,288. In this a separate link is received 
by the primary yoke that allows for rotation therewith. The manner of 
rotation is again a pin which extends through an oversized hole or slot. 
The same problems are provided by this design as with those previously 
discussed in addition to an additional arm that must be manufactured and 
assembled. The clinking with the operation of the device is consistent 
with those previously discussed. 
This issue of noise due to the adjoining arm and yoke was addressed by 
Stratton et al. in U.S. Pat. No. 4,793,020 by providing a cushion therein. 
The cushion disclosed in the form of a tape is intended as an insulation 
only. No articulation method such as a pivot pin or similar devices are 
used that would provide a method of allowing the blade to rotate along the 
long axis of the blade. 
Numerous other devices have been disclosed that address the issue of 
complying to the curved surface of the windshield, such as that by 
Lukaszewski in U.S. Pat. No. 5,136,749. In this patent, a primary yoke and 
a secondary yoke are used thereby providing an increased number of points 
of force application to the blade toward the windshield. The limitation of 
these devices is that they do not address the associated wear problems and 
lack of adequate cleaning when the blade is pushed across the surface of 
the windshield and not pulled, which can be solved by allowing the blade 
to rotate. To provide proper function of the blade assembly the 
combination of increased articulation and rotation must be employed. 
SUMMARY OF THE INVENTION 
The object of the disclosed invention is to provide optimal cleaning 
efficiency and prolonged life of a windshield wiper blade as it is used on 
a vehicle. The structure is comprised of primary and secondary yokes, the 
primary of which is attached to an actuated arm. The multiple yokes 
provide greater dexterity to the flexible blade. 
Between the primary and secondary yokes, at their respective pivot points, 
there is provided an elastic cushion which allows rotation along the long 
axis of the secondary yoke with respect to the primary yoke. This action 
allows the blade to rotate and therefore be pulled across the surface of 
the windshield, creating a smooth cleaning motion. The cushion provides 
the ability to rotate in a stable, quiet manner without the sloppy 
clinking noise which would exist without the cushion. 
The device is disclosed with a duel yoke mechanism but the invention is not 
limited thereto. The cushion could exist in a similar manner at the arm 
and primary yoke joint, with or without the existence of the secondary 
yokes. The primary yoke could be attached directly to the blade. This 
version is not disclosed in more detail because it is felt that the 
preferred embodiment incorporates the multiple yoke method. It is also 
considered optimal to use the rotateable cushioned joints at the primary 
to secondary yoke pivots instead of the arm to primary yoke joint. This 
provides increased stability of the wiper blade to the arm.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
Referring to the drawings, a windshield wiper blade assembly, constructed 
in accordance with the present invention is shown in FIG. 1, and comprises 
a wiper blade 10 which includes a support structure 12 to which the 
secondary yoke 14 is attached via the attachment clips 16. A pair of 
secondary yokes 14 located distally on the blade 10 provide the means for 
support of the blade 10 in an upright position, perpendicular to a bottom 
edge 18 of the blade 10. The secondary yoke 14 is pivotally mounted to a 
primary yoke 20 at the distal ends thereof with a pivot rod 22. The pivot 
rod 22 is designed such that it allows axial rotation about the axis of 
the rod 22 but also limited rotational movement perpendicular to the long 
axis of said rod 22. Rotation about the long axis of the rod 22 provides a 
downward three on the blade 10 so as to provide a force necessary to 
conform the flexible blade 10 to the surface of the windshield, whether it 
be flat or curved. The rotation perpendicular to the long axis of the rod 
22 allows the secondary yoke 14, and therefore the blade 10 to be dragged 
across the surface as would result from the action of a drive arm 24 which 
pivotally fastens to the primary yoke 20 via the retaining clip 26. The 
drive arm 24 moves the assembly 28 in a reciprocating manner about an axis 
30 to remove debris from the surface contacted by the bottom edge 18 of 
the blade 10. 
The invention can further be seen in the exploded view of FIG. 2, in which 
the distal portion of the primary yoke 32 is shown with the pivot rod 22, 
secondary yoke 14 and the blade 10. Retaining caps 34 are used to secure 
the rod 22 to the primary yoke 32 with a pair of elastic side supports 36 
included and located on either side of the secondary yoke 14 fastened 
through a hole 38 located therein. The pivot rod 22 has a center portion 
and a pair of opposite end portions extending in opposite directions from 
the center portion of the pivot rod 22. The pivot rod 22 is shown here to 
be provided with a spherical portion located at a center portion thereof, 
thus providing a controlled rotation perpendicular to the long axis of the 
pivot rod 22. The center portion of the pivot rod 22 extends through the 
hole 38 in the secondary yoke 14. The elastic side supports 36 are 
inserted over the opposite end portions of the pivot rod 22 and disposed 
at opposite sides of the secondary yoke 14 so as to thereby restrict the 
rotation of the secondary yoke 14 in the afore stated direction which is 
further illustrated in FIG. 3. 
With reference to FIG. 3, an end view of the distal portion of the 
invention showing the primary yoke 32 with the pivot rod 22 connected by 
the retaining caps 34 and the elastic side supports 36 surrounding the 
secondary yoke 14 supporting the blade 10 is displayed. In this view the 
device is shown in a neutral position without a side load on the blade 
causing planar movement thereto. The proximity of the elastic side 
supports 36 with respect to the secondary yoke 14 and the side walls of 
the primary yoke 32 accurately depict the unloaded tendency of the blade 
10 and yoke 14 to extend from the primary yoke 32 perpendicular to the 
long axis of the pivot rod 22. 
In FIG. 4 the view is similar to that shown in FIG. 3 only the secondary 
yoke 14 and blade 10 are shown at some angle (beta) with respect to 
perpendicular to the surface 40 to the cleaned by the blade 10. This would 
result as a consequence of the right to left motion of the assembly (as 
indicated by the arrow 42) with respect to the surface 40. The secondary 
yoke 14 rotates about the articulating surface of the pivot rod 22 and 
applying a force to the elastic side supports 36, deforming same. This 
elastic spring tension allows a controlled rotation of the secondary yoke 
14 without excess noise and sloppy clearances in the mating parts. The 
device would act as a mirror image of what is depicted here when the 
direction of movement changed from left to right, the secondary yoke 14 
trailing to the left. 
An alternative to the preferred embodiment is depicted in FIG. 5, in that 
the view is again similar to that of FIG. 3 the alteration being that of 
the smooth pivot rod 44 and the chamfered secondary yoke 46. The function 
of these items in the invention are the same as earlier described in that 
the elastic side supports 36 are captured between the sides of the primary 
yoke 32 and the secondary yoke 46. Here the spherical portion of the pivot 
rod has been removed and with it a portion of the hole in the secondary 
yoke has been made out of round so as to permit the same controlled planar 
rotation as previously described. 
FIG. 6 illustrates the movement of the secondary yoke 46 of the invention 
about the smooth pivot rod 44 as it deforms the elastic side supports 36 
as the device moves across the surface 48 in a left to right motion as 
depicted by the arrow 50. The process is similar to that earlier 
described, the alteration being that of potential reduced manufacturing 
costs and thereby potentially expanding the market for this invention. 
The rotation as discussed is achieved at the joint of the primary and 
secondary yokes of the invention. A similar result could be achieved by 
utilizing a single pivot at be joint of the drive arm and the primary 
yoke. It has been determined that the optimal area for this rotation in 
this type of double yoke design is at the area disclosed. The inventor 
recognizes the potential for alterations in blade structure designs and 
includes such obvious alternative designs to be adaptable to the disclosed 
invention.