Connecting links for windshield wipers and method for fabricating the link

The connecting link is manufactured from an elongated hollow extrusion of aluminum, which can be cut to any desired length and bent, as required. Molded plastic coupling members have tongues which are inserted into the open ends of the hollow extrusion and crimped in place to hold them securely. The coupling members have integrally formed socket structures to receive complementary ball structures which form the pivot connections of the wiper system.

BACKGROUND AND SUMMARY OF THE INVENTION 
The present invention relates generally to linkage systems. More 
particularly, the invention relates to a linkage system for the windshield 
wiper which is strong, lightweight and readily adaptable to a variety of 
different windshield wiper configurations. 
The automotive windshield wiper system typically consists of an actuator 
motor (either electric, air or hydraulic) coupled through suitable linkage 
to a pivot assembly which in turn drives the wiper arms and blades. 
Conventionally, the actuator motor is disposed in a suitable location 
usually in the engine compartment near the windshield. The pivot 
assemblies are likewise disposed adjacent the lower edge of the windshield 
and transmit motion of the motor to the wiper arms. The desired wipe angle 
and the cleaning area on the windshield are obtained by properly selecting 
the length and configuration of the linkage and of the wiper arms attached 
to the shaft of the pivot assembly. In most applications two arms and 
blades are actuated by a single motor through the use of two or more 
connecting links. These connecting links are therefore an important 
component of most windshield wiper systems. 
There are numerous different automotive body styles and correspondingly 
numerous different windshield wiper systems and configurations. 
Conventionally, the windshield wiper linkage has consisted of one or more 
links made of flat stamped steel members or steel conduit tubing. To 
accommodate the variation in sizes and geometries of different wiper 
systems it has often been necessary to re-engineer and retool the linkage 
with each wipe system design change. Thus, traditionally, there has been 
very little opportunity for standardization of the linkage components. The 
lack of standardization adds to the overall cost of the vehicle, since the 
tooling, manufacturing and inventory costs are all increased by the need 
to maintain all of these different configurations and designs. 
Aside from the higher cost, conventional steel links are heavy and tend to 
degrade the performance and longevity of the wiper system. This can be 
better understood when one considers that a typical wiper changes 
directions as much as 130 times per minute. Inertia is therefore a factor. 
Acceleration and deceleration forces exert loads on the wiper linkage, 
especially at the connecting points, and these loads add to the loads 
required to move the arms and blades back and forth across the windshield. 
Moreover, each time the direction of motion changes there are forces 
transmitted back to the motor which result in back and forth thrusting 
forces being applied to the motor armature. This can become a source of 
noise and wear as the armature bounces against the thrusting surface. 
Therefore, it would be desirable to reduce the weight of the linkage as 
much as possible, since this would lower the inertia, reduce the load 
placed on the actuator motor and minimize noise and wear. 
While reduction of weight is desirable for the reasons set forth above, 
simply making the linkage thinner is not desirable, since strength would 
be sacrificed. Strength is quite important, since the wiper system must 
function not only on rainy days, but also on snowy and icy days. On snowy 
and icy days considerably greater strength is required since the wipers 
are used to move heavy amounts of snow or to break the wiper blades free 
of an icing condition. 
The present invention provides a fresh approach to the design and 
manufacture of windshield wiper linkage which results in a linkage that is 
considerably lighter than conventional linkage and with the strength 
equivalent to or better than conventional linkage. The linkage employs an 
elongated hollow extrusion of aluminum or other suitable lightweight 
material which is open at at least one end to receive a coupling member 
which has a tongue portion disposed in the open end of the extruded 
member. The coupling member defines a pivot-forming structure for 
connection to the pivot linkage of the wiper. 
In the presently preferred embodiment the extruded member is fabricated 
from aluminum and is formed with radius interior corners to provide extra 
strength. The coupling member of the presently preferred embodiment is an 
injection molded plastic material which is readily and economically 
manufactured and which is exhibits good pivot wear characteristics. The 
presently preferred pivot structure is a ball and socket arrangement. 
The present invention also provides a method of manufacturing the wiper 
linkage whereby an elongated member is extruded and cut to suitable length 
leaving at least one open end. A coupling member, preferably of molded 
plastic, is formed and inserted into the open end of the elongated member. 
The coupling member is formed with a tongue which is inserted into the 
open end of the elongated member. The elongated member is then crimped or 
otherwise suitably formed to form a mechanical engagement with the tongue. 
This secures the coupling member to the elongated member. The coupling 
member can be formed to include a pivot-forming socket and the linkage is 
then suitably secured to the pivot assembly of the wiper by snap-fit 
engagement of the pivot assembly ball into the pivot-forming socket. 
For a more complete understanding of the invention, its objects and 
advantages, reference may be had to the following specification and to the 
accompanying drawings.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
The connecting link of the present invention is adapted for connecting the 
pivot linkage of a windshield wiper to the associated actuator motor. 
Accordingly, in FIG. 1 an exemplary windshield wiper system is illustrated 
generally at 20. The system includes an actuator motor 22, which may be 
any suitable motor such as electric, air or hydraulic. Attached to motor 
22 is a suitable crank linkage 24 for converting rotary motion of the 
motor into reciprocating motion. The crank linkage is in turn connected to 
the connecting links 26, which are manufactured and configured in 
accordance with the present invention. In the embodiment of FIG. 1 two 
connecting links have been illustrated, one for each of the two windshield 
wipers 28. Connecting links 26 are coupled at their opposite ends to the 
pivot linkage 30. If desired, intermediate linkage may be employed to 
suitably alter the motion of the wiper, according to the particular wiper 
system design. Such intermediate linkage may be fabricated according to 
the principles of the invention. Also, if desired, the connecting links 26 
may be bent or angled to accommodate the particular wiper system design. 
To illustrate the principles of the connecting link and its method of 
fabrication, refer to FIG. 2. In FIG. 2 a single connecting link 26 has 
been illustrated. The link comprises an elongated hollow extruded member 
34 and at least one coupling member 36. In FIG. 2 two coupling members 36 
are illustrated. 
The elongated hollow extruded member is preferably fabricated by extruding 
aluminum into hollow stock of generally rectangular cross-section as 
illustrated in FIG. 3. In FIG. 3, the extruded member 34 has a pair of 
oppositely disposed long sidewalls 38 and a pair of oppositely disposed 
short sidewalls 40. The sidewalls meet to form corners which are increased 
in thickness as by being radiused, as at 42. By forming radiuses at the 
interior corners the corners are made thicker than the average thickness 
of the sidewalls 38 and 40. This results in a strong extruded member which 
can be curved or bent to accommodate the particular wiper system design. 
Coupling member 36 is preferably fabricated by injection molding a plastic 
material or thermoplastic material such as acetal resin. The presently 
preferred acetal resin is known by the trade designation DERLIN 507, 
available from dupont Corporation. 
The coupling member is formed to include a tongue portion 44, which is 
adapted to slidably fit into the open end 46 of the extruded member 34. 
The coupling member is also formed to define a pivot-forming structure 48, 
which is adapted to receive the pivot linkage 30. The presently preferred 
embodiment is designed to work with a pivot linkage of the ball and socket 
variety. The pivot linkage is provided with a ball structure (seen in FIG. 
9) and the pivot forming structure 48 of coupling member 36 is fabricated 
to receive this ball by snap fit. 
Coupling member 36 is secured to the hollow extruded member by a suitable 
procedure such as by crimping. This may be seen in FIG. 4 generally at 50. 
The connecting link of the invention may utilize various different coupling 
member configurations. There are two presently preferred forms, a closed 
socket form and an open socket form. The closed socket form was depicted 
in FIGS. 2 and 4 and is fully illustrated in FIGS. 6-9. The open socket 
form is fully illustrated in FIGS. 10 and 11. 
Referring to FIGS. 6-9 it will be seen that the tongue portion 44 is 
preformed with a series of indentations 52 which are designed to mate with 
the walls of the extruded member at the crimped region adjacent the open 
end of the extruded member. 
As illustrated in FIGS. 6-9, the pivot-forming structure 48 defines a 
socket 53, which may be closed at one end by wall 54 and open at the other 
end 56 to receive the ball structure 58 (FIG. 9) of the pivot linkage 30 
or of the crank linkage 24. The pivot-forming structure may be provided 
with an annular groove 60 designed to receive the rim 62 (FIG. 12F) of a 
flexible rubber boot used to prevent dirt and other contaminants from 
entering the socket 53. Preferably socket 53 is designed to receive ball 
58 in a snap fit fashion. Thus the pivot-forming structure 48 is provided 
with a second annular groove 64, of a generally V-shaped cross-section, 
which allows the sidewalls 66 at open end 56 to flex radially outwardly as 
ball 58 is inserted and then snap back to retain the ball in the socket. 
In many applications, where the connecting link needs to connect to only 
one pivot structure at each end, the embodiment of FIGS. 6-9 is preferred, 
since the socket 53 is closed by wall 54 and thus requires only one boot 
in order to seal the ball and socket and prevent dirt and contamination 
from entering. Some applications, however, dictate that the connecting 
link accommodate a plurality of pivot connections at a given end. In this 
case, the crank linkage may be provided with a shaft having two ball-like 
structures, one for each of the two connecting links 26 (see FIG. 11). 
Such an application may utilize a connecting link of the type illustrated 
in FIGS. 10 and 11, in which the wall 54 is eliminated and the socket is 
open. With the socket open, the ball 58 can be provided with an extension 
shaft 68 which passes through opening 70, to allow a second ball structure 
72 to be attached. In this embodiment, two rubber boots might be employed 
to seal the socket and these may be press fit into annular groove 60 and 
annular groove 74. 
The method of fabricating the connecting link in accordance with the 
invention is illustrated in FIGS. 12A-12F. In FIG. 12A an elongated hollow 
stock 76 is extruded and cut to length to form the elongated hollow 
extruded member 34. A suitable extrusion die 78 has been illustration in 
FIG. 12A. Next, as illustrated in FIG. 12B, the hollow extruded member 34 
can be bent using suitable dies or roll forming equipment, or the like. 
Next, the coupling members are installed by sliding the tongue portion 44 
into the open end 46 of the extruded member 34. The presently preferred 
embodiment includes a protrusion 78 on the tongue portion which is 
designed to engage the interior of the extruded member, to hold the tongue 
portion in place during the following manufacturing steps. Installation of 
the coupling members in this fashion has been illustrated in FIGS. 12C and 
12D. 
After the coupling members are installed and held in place by means of the 
protrusion 78, a crimping die 80 is applied as illustrated in FIG. 12E. 
Preferably, the die is positioned to register with the indentations 52 
which were formed in the coupling member. Thus, when the crimping action 
is performed, the metal sidewalls of the extruded member conform to and 
lock with the indentations of the coupling member. This prevents the 
coupling member from being separated from or pulled out of the extruded 
member. Next, as illustrated in FIG. 12F, the ball 58 of the linkage 
structure is press fit into the socket 53 of coupling member 36. In 
addition, the annular edge 62 of boot 84 is inserted into the annular 
groove 60 to form a seal. While the series of FIGS. 12A-12F have 
illustrated the fabrication at one end of the connecting link, it will be 
understood that the same procedure may be followed to form the opposite 
end. 
From the foregoing, it will be seen that the present invention provides an 
economical , lightweight and strong connecting link to replace 
conventional stamped steel and tubular steel links in windshield wiper 
systems. The method of manufacturing or fabricating the connecting link 
lends itself well to mass production operations and particularly 
operations where standardization is desirable. 
While the invention has been illustrated and described in its presently 
preferred embodiments, it will be understood that the present invention is 
capable of certain modification without departing from the spirit of the 
invention as set forth in appended claims.