U.S. patent application number 10/266559 was filed with the patent office on 2004-04-08 for plastic fastener.
Invention is credited to Hull, Michael L., Sarkar, Debabrata, Shields, Steve J..
Application Number | 20040066106 10/266559 |
Document ID | / |
Family ID | 32042707 |
Filed Date | 2004-04-08 |
United States Patent
Application |
20040066106 |
Kind Code |
A1 |
Hull, Michael L. ; et
al. |
April 8, 2004 |
PLASTIC FASTENER
Abstract
A plastic fastener is disclosed. The fastener may be employed in
a vehicle generator. The fastener has a plastic body extending
through an aperture of a first component and through an aperture of
a second component. The body has a first distal head that
retainingly abuts the opening of the aperture of the first
component. The plastic body also has a second distal head that
retainingly abuts the opening of the aperture of the second
component. The configuration of the body secures the first
component to the second component. The invention further provides a
method of fastening components of a vehicular generator. A plastic
body with first and second studs is over molded about a first
generator component. At least one stud may be extended through an
aperture of a second generator component. The studs are then formed
into distal heads to secure the first component to the second
component.
Inventors: |
Hull, Michael L.; (Anderson,
IN) ; Sarkar, Debabrata; (Anderson, IN) ;
Shields, Steve J.; (Muncie, IN) |
Correspondence
Address: |
MARGARET A. DOBROWITSKY
DELPHI TECHNOLOGIES, INC.
Legal Staff, Mail Code: 480-410-202
P.O. Box 5052
Troy
MI
48007-5052
US
|
Family ID: |
32042707 |
Appl. No.: |
10/266559 |
Filed: |
October 8, 2002 |
Current U.S.
Class: |
310/91 ;
310/68D |
Current CPC
Class: |
F16B 5/04 20130101; F16B
19/06 20130101; F16B 43/002 20130101; H02K 11/046 20130101 |
Class at
Publication: |
310/091 ;
310/068.00D |
International
Class: |
H02K 005/00 |
Claims
1. A plastic fastener for a vehicular generator, comprising: a body
extending through an aperture of a first component of said
vehicular generator and said body extending through an aperture of
a second component of said vehicular generator, said body having a
first distal head retainingly abutting an outer opening of said
aperture of said first component, and said body having a second
distal head retainingly abutting an outer opening of said aperture
of said second component, whereby said first component is secured
to said second component.
2. The plastic fastener of claim 1, wherein said body is
retainingly contractable about an outer lip surface of said
aperture of said first component, and wherein said body is
retainingly expandable about an inner lip surface of said aperture
of said first component.
3. The plastic fastener of claim 1, wherein said first distal head
has a diameter larger than the diameter of said aperture of said
first component, and said second distal head has a diameter larger
than the diameter of said aperture of said second component.
4. The plastic fastener of claim 1, wherein said first component
comprises a heat sink and said second component comprises a slip
ring end frame.
5. The plastic fastener of claim 1, wherein said body further
extends through an aperture of a third component of said vehicular
generator, said third component interposed between said first
component and said first distal head.
6. The plastic fastener of claim 5, wherein said first component
comprises a heat sink, said second component comprises a slip end
frame, and said third component comprises a terminal assembly.
7. The plastic fastener of claim 1, wherein said first component
comprises a brush box and said second component comprises a voltage
regulator.
8. The plastic fastener of claim 1, wherein said aperture of said
first component and said aperture of said second component are
coaxial.
9. The plastic fastener of claim 1, wherein said aperture of said
first component and said aperture of said second component are
axially offset.
10. A method of fastening components of a vehicular generator,
comprising: providing a first component of said vehicular
generator, said first component having an aperture; extending a
plastic body through said aperture of first component, said body
having a first stud end and a second stud end; extending said
second stud through an aperture of a second component of said
vehicular generator; forming said first stud into a first distal
head that retainingly abuts an outer opening of said aperture of
said first component; and forming said second stud into a second
distal head that retainingly abuts an outer opening of said
aperture of said second component, whereby said first component is
secured to said second component.
11. The method of claim 10, wherein said steps of forming said
first and second studs comprise ultrasonic welding said first and
second studs.
12. The method of claim 10, wherein said steps of forming said
first and second studs comprise heat staking said first and second
studs.
13. The method of claim 10, wherein said step of extending said
plastic body through said aperture of said first component
comprises over-molding said plastic body in said aperture of said
first component.
14. The method of claim 13, wherein said over-molding comprises
over-molding said plastic body in an aperture of a heat sink of
said vehicular generator.
15. The method of claim 14, wherein said step of extending said
second stud comprises extending said second stud through a slip
ring end frame of said vehicular generator.
16. The method of claim 14, further comprising extending said first
stud through a terminal assembly of said vehicular generator.
17. The method of claim 10, wherein said step of extending said
first stud comprises extending said first stud through an aperture
in a voltage regulator assembly of said vehicular generator and
wherein said step of extending said second stud comprises extending
said second stud through slip ring end frame of said vehicular
generator.
18. A plastic fastener, comprising: a body extending through an
aperture of a first component and said body extending through an
aperture of a second component, said body having a first distal
head retainingly abutting an outer opening of said aperture of said
first component, and said body having a second distal head
retainingly abutting an outer opening of said aperture of said
second component, whereby said first component is secured to said
second component.
Description
TECHNICAL FIELD
[0001] The present invention relates to a plastic fastener and a
method of fastening components.
BACKGROUND OF THE INVENTION
[0002] A conventional vehicular generator, sometimes referred to as
an alternator, includes a variety of electrical components, such as
a positive heat sink, a rectifier bridge, a brush box, and a
voltage regulator. These components are commonly secured to each
other and/or to the generator frame. Mounting the components in
this fashion enhances heat transfer within the generator, secures
the electrical components so as to reduce damaging vibrations, and
may provide electrical grounds and positive electrical connections
between various components.
[0003] The electrical components are commonly mounted with threaded
fasteners, such as screws. However in order to maintain electrical
isolation between the fastener, components, and frame, plastic or
other insulators are typically required. Such an approach is shown
in U.S. Pat. No. 6,034,012 to Chen et al., which depicts a mounting
bolt (255) having an insulator (256) for insulating the slip ring
end housing (74) from the rectifier (252). A similar approach is
also shown in U.S. Pat. No. 5,712,517 to Schmidt et al., which
illustrates rivets (75) with rivet insulators (76) that are used to
secure an interconnection plate (70) to an upper surface (9) of a
control plate/heat sink (10).
[0004] Nevertheless, the typical method of securing generator
components with insulated threaded fasteners presents several
challenges. To avoid loosening of the fastener, the fastener must
be maintained at a high tension. This tension results in a
continuously high compressive load on the plastic insulator at high
temperatures. Under such a load, the plastic insulator may creep,
and loosen the fastener. Loose fasteners may lead to a lower
compressive load on the components in the stack-up, which may
deteriorate the necessary electrical contact between the
components.
[0005] There is consequently a need in the art for a vehicular
generator fastener, and/or a method of fastening components of a
vehicular generator, that overcomes one or more of the above
limitations.
SUMMARY OF THE INVENTION
[0006] One object of the present invention is to provide a solution
to one or more problems set forth above. One advantage of the
present invention is that a plastic fastener, as disclosed herein,
replaces more expensive steel screws and related accessories, such
as compression limiters, and/or spring elements like crest-cup
washers. Since the present invention serves as both a fastener and
an insulator, it more efficiently utilizes available package space
where the accommodation of both metal fasteners and necessary
insulation may be required. In addition, as the plastic fastener is
an electrical insulator, the inventive fastener reduces local
grounding of the components, such as salt bridging. Moreover,
because the plastic fastener is more flexible than a metal screw,
greater tolerances may be designed in the stack up of mating
components; that is, the mounting aperture of a first component
need not align exactly with the mounting aperture of a second
component.
[0007] It is a primary object of the present invention to overcome
the foregoing problems and/or to satisfy at least one of the
aforementioned needs. The invention provides a plastic fastener for
a vehicular generator having a body that extends through an
aperture of a first component of the generator and that extends
through an aperture of a second component of the generator. The
plastic body has a first distal head that retainingly abuts an
outer opening of the aperture of the first component. The plastic
body also has a second distal head that retainingly abuts an outer
opening of the aperture of the second component. The configuration
of the plastic body secures the first component to the second
component.
[0008] The invention further provides a method of fastening
components of a vehicular generator. A first component of the
generator is provided. The first component has an aperture. A
plastic body is extended through the aperture of the first
component. The plastic body has a first stud end and a second stud
end. The second stud end is extended through an aperture of a
second component of the generator. The first stud is then formed
into a first distal head that retainingly abuts an outer opening of
the aperture of the first component. The second stud is formed into
a second distal head that retainingly abuts an outer opening of the
aperture of the second component. This method secures the first
component to the second component.
BRIEF DESCRIPTION OF THE DRAWINGS
[0009] The present invention will now be described, by way of
example, with reference to the accompanying drawings, in which:
[0010] FIG. 1 is a cross sectional view of a partially manufactured
plastic fastener according to the present invention in one
environment of a vehicular generator.
[0011] FIG. 2 is a cross sectional view of a fully manufactured
plastic fastener according to the present invention in the
environment shown in FIG. 1.
[0012] FIG. 3 is a cross sectional view of a fully manufactured
plastic fastener according to the present invention in another
environment.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0013] Referring now to the Figures wherein like reference numerals
are used to identify identical components in the various views,
FIG. 1 depicts a partially manufactured plastic fastener 10 in one
embodiment of a vehicular generator. Fastener 10 may be constructed
in a manner more fully described below. Fastener 10 may be used to
secure one or more components of a vehicular generator to another
component. In the embodiment shown in FIG. 1, fastener 10 is
utilized in a rectifier assembly 12, and specifically is positioned
to secure a positive heat sink 14 and terminal assembly 16 to a
slip ring end (SRE) frame 18.
[0014] In order to more fully appreciate the inventive fastener 10,
the surrounding environment of FIG. 1 will first be described in
more detail. Rectifier assembly 12 is provided to rectify the
output voltage of an alternating current generator. It may be used
as part of an air-cooled or water-cooled generator. Positive heat
sink 14 may be generally arc shaped and may be made out of a
thermally and electrically conductive material, such as aluminum.
Positive heat sink 14 may include one or more diode mounts 20, and
one or more apertures 22 for supporting fastener 10 in the manner
described below.
[0015] Each diode mount 20 is adapted to retain a respective diode
24 in a thermally and electrically conductive manner; Heat from
diode 24 is transferred to heat sink 14 to provide the desired heat
sink effect. Diode 24 may be of the press-fit variety. In the
depicted environment, press-fit diode 24 is commonly referred to as
a positive-side diode, and heat sink 14 is commonly referred to as
a positive heat sink since a positive direct voltage is developed
on heat sink 14.
[0016] SRE frame 18 provides an outer portion of a housing
structure for the generator. It cooperates with a drive end frame
(not shown) to define an interior space (not shown) to house a
rotor assembly (not shown). SRE frame may be made out of cast
aluminum, or other suitable thermally and electrically conductive
material. SRE frame 18 may include one or more diode mounts 26, and
one or more through bores, or apertures, 28 for supporting fastener
10 in the manner described below.
[0017] In the environment shown in FIG. 1, SRE frame 18
additionally serves as a negative heat sink. Each diode mount 26 is
adapted to retain a respective diode 30 in a thermally and
electrically conductive manner. Heat from diode 30 is transferred
to SRE frame 18 to provide the desired heat sink effect. Like diode
24, diode 30 may be of the press-fit variety. In the depicted
environment, press-fit diode 30 is commonly referred to as a
negative-side diode, and SRE frame 18 may serve as a negative heat
sink since a negative direct voltage is developed on SRE frame
18.
[0018] Terminal assembly 16 may be provided for electrically
connecting phase leads (not shown) from a stator to diodes 24, 30,
in a manner not depicted herein. Terminal assembly 16 may be made
from an electrically conductive material, such as copper, and may
further include an overcoating of plastic, or other electrically
insulating material, which may provide additional rigidity.
Terminal assembly 16 may include an aperture 32 for receiving
fastener 10.
[0019] Rectifier assembly 12 may also include rear cover 34. Cover
34 may be a plastic cover with air flow passages (not shown). Cover
34 may be provided to protect the generator from inadvertent
grounding, and may assist in preventing contamination of the
generator.
[0020] With the recitation of the foregoing environment, a
preferred embodiment of the inventive fastener, and method of
fastening, will now be detailed. Fastener 10 may be made from a
variety of plastics that are durable enough to withstand loads of
0-50 Newtons and temperatures of -40 to 150 degrees Celsius.
Notwithstanding the foregoing force and temperature ranges for the
above described environment, those skilled in the art will
recognize that the inventive fastener may accommodate other ranges
in other environments in which the fastener may be employed.
[0021] Fastener 10 may generally include a body 36, a stud 38, and
a stud 40. Body 36 extends through aperture 22 of heat sink 14 and
through aperture 28 of SRE frame 18. Body 36 may additionally
extend through aperture 32 of terminal assembly 16. Stud 38 extends
beyond aperture 22 and, if fastener 10 is utilized to secure
terminal assembly 16, then stud 38 extends beyond aperture 32. Stud
40 extends beyond aperture 28.
[0022] Fastener 10 may be formed by over molding body 36, stud 38,
and stud 40 about heat sink 14. In particular, aperture 22 may be
pierced, or sledged, in heat sink 14, such that upper lip 42 and
lower lip 44 of aperture 22 are formed. Body 36, with stud 38 and
stud 40, may then be over molded within aperture 22. Upper lip 42
and lower lip 44 provide additional surface area to anchor fastener
10 to heat sink 14. Specifically, upper lip 42 and lower lip 44
define outer lip surfaces 46 and inner lip surfaces 48 to anchor
fastener 10 at either high or low temperature extremes of the
surrounding environment. During low temperature extremes, fastener
10 contracts down on surface 46 tightly. Similarly, in high
temperature extremes fastener 10 expands toward surface 48 tightly.
Accordingly, at either temperature extreme fastener 10 may hold the
components of the generator securely.
[0023] As shown in FIG. 1, body 36 may extend beyond aperture 22
and be over molded and disposed about heat sink 14. Upon being
formed about heat sink 14, stud 40 may be positioned through
aperture 28, and stud 38 may be optionally extended through
aperture 32. It will be appreciated by those skilled in the art
that fastener 10 may be formed about heat sink 14 through other
conventional methods. Moreover additional fasteners, such as the
partially shown fastener 10A in FIG. 1, may be employed within an
environment of a vehicular generator.
[0024] FIG. 2 depicts fastener 10 in a completely manufactured form
10'. In fastener 10', stud 38 and stud 40 have been formed into
distal head 50 and distal head 52, respectively. Distal head 50
abuts aperture 32 to retain heat sink 14. As shown in FIG. 2,
terminal assembly 16 may be interposed between heat sink 14 and
distal head 50, such that distal head 50 abuts aperture 32 to
secure terminal assembly 16 relative to heat sink 14. Similarly,
distal head 52 abuts aperture 28 to secure heat sink 14 to SRE
frame 18.
[0025] Distal head 50 and distal head 52 may be formed by
ultrasonic welding stud 38 and stud 40. Those skilled in the art
will appreciate that other manufacturing methods, such as heat
staking, may be similarly effective in forming distal heads 50 and
52. Distal head 50 is formed such that it has a diameter larger
than the diameter of the opening of aperture 32 to which it abuts.
Similarly, distal head 52 is formed such that it has a diameter
larger than the diameter of the opening of aperture 28 to which it
abuts.
[0026] While FIGS. 1 and 2 depict fastener 10 and 10' in one
environment of a vehicular generator, it will be appreciated by
those skilled in the art that the inventive fastener 10' may be
employed in other environments where similar benefits can be
realized. FIG. 3 represents the utilization of fastener 10' to
secure components in other such environments. Fastener 10' is shown
in FIG. 3 with its body 36, distal head 50, and distal head 52. In
this environment, for example, fastener 10' may secure one
component 54 to a second component 56. Such components may include,
for example, a brush box assembly and voltage regulator,
respectively.
[0027] Like heat sink 14, component 54 includes an aperture 58 that
may be pierced, or sledged, to form an upper lip 60 and a lower lip
62. Lips 60 and 62 define outer lip surface 64 and inner lip
surface 66 for securing body 36 when it contracts and expands,
respectively, at varying operating temperatures of the environment.
Like SRE frame 18, component 56 includes an aperture 68. Distal
head 50 and distal head 52 retainingly abut the outer openings of
aperture 58 and aperture 68, respectively, to secure component 54
to component 56. While apertures 58 and 68 are coaxial in the
illustrated embodiment, it will be appreciated by those skilled in
the art that due to the flexibility of fastener 10', both
inherently and since it may be over molded to in a variety of
shapes, apertures 58 and 68 may be offset from each other.
[0028] The present invention may be employed in any application
where the retention stress on the joint to be fastened is within
the capabilities of the plastic material chosen. Further, the
inventive fastener may be beneficially employed in environments
which are exposed to temperature fluctuations.
[0029] While the present invention has been described with
reference to certain preferred embodiments and implementations, it
is understood that various modifications and variations will no
doubt occur to those skilled in the art to which this invention
pertains. These and all other such variations which basically rely
of the teachings through which this disclosure has advanced the art
are properly considered within the scope of this invention.
* * * * *