Wiper system double ball joint

A double ball joint assembly for use with a windshield wiper system. The double ball joint assembly includes a first ball affixed to a second ball such that a first drive link is retained between them. A first socket is coupled to the first ball and includes an annular groove for retaining a second drive link about its circumference. A second socket is coupled to the second ball and includes an annular groove for retaining a motor crank arm that is coupled to a wiper motor assembly. This double ball assembly produces a shorter overall double ball joint.

FIELD OF THE INVENTION 
The present invention relates to mechanisms that drive wiper systems in a 
vehicle, and more particularly to double ball joints used in vehicle wiper 
drive systems. 
BACKGROUND OF THE INVENTION 
With an emphasis today on increasing vehicle fuel economy, cars and light 
trucks are being reduced in size where possible to help reduce the overall 
weight of the vehicle. In doing so, the space allowed for various systems 
in vehicles is also shrinking. This, in turn, requires that the various 
systems themselves must be reduced in size, typically by reducing the size 
of their individual parts within the various systems or by reconfiguring 
the assemblies of these systems to be more compact. 
In the case of a drive mechanism for windshield wipers, this creates a 
desire to reduce the height of the traditionally "tall" double ball joint 
construction used for coupling a wiper motor crank lever to the two drive 
links in a drive-drive wiper system. This reduction in the overall size of 
the wiper system will thereby allow easier packaging of the wiper system 
into a vehicle as well as help to reduce weight. 
An example of a "tall" double ball joint system is disclosed in U.S. Pat. 
3,749,431 to Schmid. Schmid discloses a double ball joint design, but it 
is undesirably tall, thus requiring more space when mounted within the 
vehicle and increasing weight. Windshield wiper rods are mounted at the 
mid-point of each socket and a crank drive is mounted beyond the end of 
one of the sockets. Since the crank drive is on the end, it does not have 
the advantage of using a more compact connection arrangement to reduce the 
overall height of the double ball connector. Reducing the overall height 
allows for better packaging of the wiper system in the vehicle sheet 
metal, thus saving space and reducing weight. 
SUMMARY OF THE INVENTION 
In its embodiments, the present invention contemplates a double ball joint 
for use with a vehicle wiper system. The double ball joint comprises a 
double ball assembly including a first ball, a second ball and a means for 
securely connecting the first ball to the second ball. The first and 
second balls include a means that creates a junction for supporting a 
first drive link between the first and second balls. A first socket is 
coupled about the first ball and includes a means adapted for supporting a 
second drive link about the first socket. A second socket is coupled about 
the second ball and includes a means for supporting a motor crank arm 
about the second socket. 
Accordingly, it is an object of the invention to provide an improved double 
ball joint construction for a wiper system that is reduced in overall 
height, and consequently reduced in weight. 
It is an advantage of the present invention that the reduced height of the 
double ball joint, being more compact, will take up less space in the 
vehicle making for easier vehicle packaging.

DETAILED DESCRIPTIONS OF THE PREFERRED EMBODIMENTS 
FIG. 1 shows an overall wiper system assembly 10 mounted to a portion of a 
vehicle structure 12 just in front of the lower edge of a windshield 16 by 
mounting screws 14. Wiper assembly 10 includes a pair of wiper arm mounts 
18 pivotally mounted to a wiper module 20. Wiper module 20 mounts and 
supports a wiper motor armature 22 and a wiper motor gear assembly 24, 
together forming wiper motor assembly 26. 
A right hand tubular drive link 28 and a left hand tubular drive link 30 
are rotatably attached at one end each of wiper arm mounts 18, via a pair 
of plates 32. The drive links are preferably made of metal, although they 
can also be made of plastic or other suitable material known to those 
skilled in the art. The other end of drive links 28 and 30 are coupled to 
a double ball joint assembly 34. The overall wiper system assembly 10 is a 
drive-drive wiper system since it has both links connected to a motor 
crank arm. This drive-drive wiper system weighs less and is shorter as 
opposed to a conventional slave drive wiper system in which only one of a 
pair of wiper drive links is directly driven by a motor. Wiper motor 
assembly 26 drives double ball joint assembly 34, which in turn, causes 
links 28 and 30 to activate wiper arm mounts 18, to which wiper arms (not 
shown) are coupled. 
Double ball joint assembly 34 is shown in more detail in FIGS. 2 and 3. It 
includes a first ball 36 and a second ball 38, preferably made of metal, 
although they could also be made of plastic. First ball 36 includes a 
spherical portion 40 having a flat side 42 and a cylindrical pin 44 
protruding from spherical portion 40 opposite flat side 42. A circular 
support ring 46 is concentric with pin 44 and adjacent to spherical 
portion 40. 
Second ball 38 includes a spherical portion 48 having a flat side 50. It 
also includes a cylindrical bore 52 through its center and concentric with 
flat side 50. A circular support ring 54 is concentric with bore 52 and 
opposite flat side 50. 
A first socket 60, preferably made of plastic, includes an internal 
spherical cavity 62 and has first and second circumferentially oriented 
support rings, 64 and 66 respectively, located externally about socket 60. 
Adjacent to first support ring 64 is an annular groove 68. A second socket 
70 is substantially identical to first socket 60. It includes an internal 
spherical cavity 72 and has first and second circumferentially oriented 
support rings, 74 and 76 respectively, located externally about socket 70. 
Adjacent to first support ring 74 is an annular groove 78. 
Double ball joint assembly 34 fits together by sliding pin 44 of first ball 
36 through a hole 82 in right hand drive link 28 and into bore 52 in 
second ball 38. The end 56 of pin 44 protrudes through the end of bore 52 
and is flattened firmly against flat side 50 of second ball 38; that is, 
the two balls are radially riveted together. The mushroomed pin 44 will 
now hold the two balls together and prevent them from rotating relative to 
one another. This forms double ball assembly 84. There is sufficient 
clearance between hole 82 in right hand drive link 28 and balls 36 and 38 
to allow relative rotation between right hand drive link 28 and the 
junction formed between first and second balls 36 and 38. In lieu of using 
a mushroomed pin, other methods could also be used to insure that the two 
balls are secured relative to one another, or the double balls could be 
formed integrally with right hand drive link 28 including a different 
mechanism for coupling to the double ball assembly between the two balls. 
First socket 60 is snapped into a hole 86 in left hand drive link 30 until 
hole 86 passes over first support ring 64 and engages within annular 
groove 68. First support ring 64 will ensure that left hand drive link 30 
is retained on first socket 60. Second socket 70 is snapped into a hole 88 
in a motor crank lever 90 until hole 88 passes over first support ring 74 
and engages within annular groove 78. 
Annular grooves 68 and 78 are oriented on sockets 60 and 70, respectively, 
such that when the sockets are assembled with the balls, grooves 68 and 78 
align approximately midway along balls 36 and 38, respectively. Wiper 
module 20 is secured in vehicle structure 12 and the right hand and left 
hand drive links are affixed to module 20. Then, double ball joint 
assembly 34 fits together by snapping first and second sockets 60 and 70 
respectively over their respective balls 36 and 38. 
A second hole 92 in motor crank arm 90 is now slipped over a threaded shaft 
94 protruding from wiper motor gear assembly 24. A nut 96 secures motor 
crank lever arm 90 to threaded shaft 94. 
Double ball joint assembly 34 for automobile windshield wiper assembly 10 
now provides a reduction in overall assembly height, thereby reducing 
weight and the size of space it takes up in vehicle structure 12. 
While certain embodiments of the present invention have been described in 
detail, those familiar with the art to which this invention relates will 
recognize various alternative designs and embodiments for practicing the 
invention as defined by the following claims.