Note: Descriptions are shown in the official language in which they were submitted.
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WINDSHIELD WIPER LINKAGE AND MET~IOD 0~ ASSEMBL,Y
Background of the Invention
The present invention relates to a ball joint as-
sembly, and more particularly, to a ball joint assem-
~ly utili~ing a one piece semi-rigid, plastic socket
5 member for use in connecting a windshield wiper
transmission linkage for motor vehicles where sub-
stantial pivotal and canting movement occurs.
Ball socket members of plastic material are known
in the prior art. Examples of such ball socket mem-
10 bers for a windshield wiper transmission linkage aredisclosed in U.S. Patents 3,749,431, 3,845,998 and
3,853,414. In these known ball socket bushings
either no seal is provided for retaining lubricant
and preventing entrance of contaminants or a lip
15 type seal integral with the ball socket is provided
to ef~ect a seal by engaging against a portion of
the ball stud. In these prior art bushings, to
effect a good sealing engagement the bush`ing must be
formed of yieldable elastomer, as for example, poly-
20 urathane. Due to the severe multi-directional
forces applied in a windshield wiper linkage a highly
yieldable bushing results in excessive movement at
the joints. Such excessive movement can produce dis-
tortion of the normal wiping pattern and cause the
?5 blade to overrun t,he molding about the windshield.
It is therefore advantageous that a strong, rigid
socket member be utiliæed. Since a multiplicity of
linkage members and joints are used in these linkages
it is advantageous for economy purposes to utilize a
30 socket member of one sizé and design for the entire
linkage system. This presents a problem because of
design and cost considerations. Metals of different
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thickness in the various linkage members are em-
ployed depending upon space and design requirements.
The socket members may be pre~lubricated. Use of a
semi-rigid material in known socket members can cause
5 fracturing during assembly due to pressure created
by the entrapment of excess grease.
Summar~ of the Inven~tion
It is an object of this invention to provide a novel,
10 improved one piece ball and socket joint which over-
comes the aforementioned difficulties and produces
advantageous features such as rigidity, strength,
resistance to fracture and relief or pressure due to
entrapment of lubricant during assembly.
Another object of the invention is to provide an
improved ball and socket member which will fit se-
curely on linkage members of various thicknezsses.
A still further object is to provide a sealing ar-
rangement to prevent entry of water, durt and other
20 contaminants to the interior of the ball socket mem-
ber and to retain the lubricant.
Other objects and advantages of the invention will
be apparent from the following detailed description
tkane in connection with the accompanying drawings.
Description of the Drawings
Fig. 1 is a partial perspective view of a motor
vehicle showing a windshield wiper which incorporates
the present invention;
Fig. 2 is an exploded perspective view of a trans-
mission linkage joint assembly of this invention;
Fig. 3 is a cross sectional view taken on line
III-III of Fib. 2 showing the joint assembly in
` assembled condition;
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Fig. 4 illustrates a modified form of a linkage
aperture in perspective; and
Fig. 5 is a sectional view taken on line V-V of
Fig. 4.
Detailed Description
Referring to the drawings in particular, Fig. 1
illustrates a motor vehicle 10 having a windshield
wiper linkage transmission 12 including a connecting
10 arm or first linkage member 14, a crank arm or sec~
ond linkage member 16 and a ball joint 18 connecting
the crank arm 16 and the connecting arm 14. A motor
(not shown) drives the connecting arm 14 to oscil-
late a pivot shaft (not shown) mounted in a pivot
15 body 20. A wiper arm and blade assembly 22 is se-
cured to the pivot shaft for oscillation therewith.
In Figs. 2 and 3 the components of the ball joint
assembly 18 are illustrated. In Fig. 2 a linkage
member 14 is shown having an aperture 24 adjacent
20 its ends with radially extending key slots 26 dia-
metrically spaced from each other. On the periphery
of the aperture 24 are forme~d circumferentially
spaced deformations 27 for a purpose to be herein-
after described. A ball socket member 28 is shown
25 for reception in the aperture 24 as shown in Fig. 3.
The ball socket member is of semi-rigid p~astic ma-
terial having a stress level which renders it yield-
able to the pressure applied during insertion into
the aperture 24; it is also yieldable ta the forces
30 applied during insertion of the ball stem member.
However, the stress level is resistant to yielding
from the canting forces applled during operation of
the wiper system. ZYTEL(R) ST 801 nylon resin manu-
factured by E. I. Dupont de Nemours & Co., Inc. and
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VALOX(R) 310 thermoplastic polyester manufactured
by Teneral Electric Co. are examples of materials
having such characteristics, In accordance with the
broader aspects of the invention other and different
- 5 materials exhibiting similar properties as described
may be employed.
The ball socket member 28 may include external ears
33 diametrically spaced from each other and position-
ed to interrupt a circumferential external groove 14
10 which interengages the periphery of the aperture 24
to retain the ball socket on the first linka~e mem-
ber 14. The deformations 27 are provided to approxi-
mate the width of groove 34 so that a secure, tight
fit is achieved. The linkage member 14' shown in
15 Fig. 3 does not require the deformations 27 since it
is of a thickness substantially equal to the width of
the groove 34. In the Fig. 4 embodiment the periph-
ery of the aperture 34 is dished as at 29 to accomo-
date the groove 34 securely when the thickness of
20 the linkage member 14 is 6reater than the width of
the groove 34.
The ball socket 28 has an internal cylindrical re-
cess 16, closed at one end, forming a lubricant
socket; it terminates at its other end in a substan-
25 tially spherical hollow portion 38 which in turnterminates in an open ended cylindrical portion 40
of smaller diameter than the diameter of the spheri-
cal portion 38. A pair of internal slots 42 in
alignment with the ears 32 extend from the open end
30 of the cylindrical recess 40 and serve as lubricant
relief slots as well as lubricant distribution means.
Location of the slots 42 in alignment with ears 32
permits the slots to be of an effective depth while
maintaining the notched impact strength; this ar-
35 ran~ement embraces resistance to fracturing during
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assembly and operation.
The second linkage member 16 has secured at an end
thereof a ball stem or stud 30 comprising a cylindri-
cal end portion 44 received in aperture 46 and peened
5 over as at 48. The ball stem 30 includes a substan-
tially spherical head 50 corresponding in si~e and
shape to the spherical hollow portion 38 of the ball
socket 28; it terminates in a cylindrical ball por-
tion 52 corresponding to the cylindrical recess 36
10 and is of greater diameter than the stem 44 forming
a shoulder 54 therebetween which seats on the pe-
riphery of the aperture 46. A seal 56 is provided
which may be of polyurethane or any other suitable
or desirable closed cell cellular material. The
15 seal 56 encircles the base portion 52 and is re-
tained by the ball 50.
A noveI method of securing the ball socket 28 to
the first linkage 14 comprises the steps of forming
an aperture in the linkage melnber 14 and deforming
20 the aperture as at 27 or 2~ to obtain an effective
thickness on the periphery Qf the aperture approxi-
mating the width of the groove 34 of the ball socket
28. Therea~ter the ball socket 28 is passed into
the aperture 24 with the ears 32 in alignment with
25 the key slots 26 and pressure is applied until the
groove 34 engages the peripher~ of the paerture 24
whereupon it is securely retained in position. The
ears 32 interrupt the groove 34 so as to serve as
keys for retaining the ball socket against rotation
30 and also to reinforce the axially slotted portion.
The link 16 with the ball stem or stud 30 and the
seal 56 attached is inserted through cyllndrical
opening 40 and pressure is applied until the cylin-
drical portion 50 of the ball 30 snaps into the
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spherical hollow portion 38 of the ball socket 28.
Sufficient pressure is applied to cause yielding of
the ball socket member 28 so as to permit entry of
the ball stud into the spherical socket. The axial
slots 42 form a relier path for expulsion of ex-
cessive grease which would otherwise be entrapped
and thus be likely to cause fracturing of the socket
member body. The stresses resulting are below the
threshold at which the ball socket is likely to
fracture. When the ball stem 30 is seated in the
socket member 28 the periphery 58 of the open end of
the ball socket 28 will seat on the seal 56 compress-
ing it slightly. While driving the ball stud 30 into
the hollow of the ball socket 28 any excess lubricant
within the bal socket will be expelled through the
slots 42 and absorbed by the seal 56. Compressing
the seal 56 serves to obviate the entry of contami-
nants into the hollow. The urethane seal 56 being
resilient permits canting of the linkage members
relative to each other.
In cases where the groove 34 is of smaller width
than the thickness of the linkage, as shown in Fig.
4, a peripheral depression or dished periphery is
formed having a greater diameter than the diameter
of the upper shoulder of the slot 34 resulting in a
peripheral edge of a width approximately the width
of the groove 34 thereby effecting a secure, tight
fit of the ball socket 28 in the aperture 24. If
the thickness of the linkage is equivalent to the
thickness of the groove 34 the peripheral forming
operation may be deleted.
A transmission linkage assembly incorporating a
unique ball and socket joint with an improved one
piece semi-rigid 3 fracture resistant ball socket
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member has been shown for the purposes of illustra-
tion. A unique seal has been shown and described.
A method of assembly which permits use of a one shape
and size ball socket for linkage members of varying
thicknesses has been shown and described for the pur-
poses of illustration. It will, of course, be under-
stood however, that other methods of assembly and
details of construction may be utilized in accord-
ance with the broader aspects of the invention and
that the peripheral deformation about the aperture
and linkage may be varied in shape and size. There-
fore, although certain specific embodiments of the
invention have been shwon and described for the pur-
pose of illustration it will of course be understood
that other embodiments and modifications which come
within the scope of the invention may be employed.
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