Information
-
Patent Grant
-
6565159
-
Patent Number
6,565,159
-
Date Filed
Thursday, October 25, 200122 years ago
-
Date Issued
Tuesday, May 20, 200321 years ago
-
Inventors
-
Original Assignees
-
Examiners
Agents
- MacMillan, Sobanski & Todd, LLC
-
CPC
-
US Classifications
Field of Search
US
- 301 35626
- 301 35632
- 301 131
- 301 132
- 301 135
- 301 64701
- 301 64702
- 301 64703
- 301 1241
- 029 520
- 029 505
- 403 279
- 403 280
- 403 282
- 280 93512
- 280 124125
-
International Classifications
-
Abstract
A wheel assembly for a vehicle comprises a spindle and a wheel carrier. The spindle includes a shank portion and a shoulder portion. The shank portion includes a press-fit portion adjacent the shoulder portion and has a first predetermined diameter. The wheel carrier is adapted to be supported by a suspension system of the vehicle, is comprised of aluminum, and has a spindle-receiving bore therethrough. The bore has an initially-formed diameter smaller than the first predetermined diameter. The press-fit portion is press-fit into the bore. The difference between the initially-formed diameter and the first predetermined diameter is sufficiently large that the press-fit portion is surrounded by a deformation zone having a radial thickness of at least 10 microns. In one preferred embodiment, this deformation zone is comprised of plastically deformed aluminum having a radial thickness of at least 3 microns.
Description
BACKGROUND OF THE INVENTION
This application is related to concurrently filed U.S. application Ser. No. (23336), entitled “Spindle Mounting for Aluminum Wheel Carrier”.
The present invention relates in general to spindles for wheel mounting in automotive vehicles, and, more specifically, to the attachment of cast iron or steel spindles to cast aluminum wheel carriers.
The use of lightweight materials in automotive vehicles is desired wherever possible in order to help increase fuel economy. Thus, the use of aluminum instead of iron or steel in vehicle suspension components is of increasing interest to vehicle manufacturers. However, the material properties of aluminum can be very different from those of iron or steel, meaning that aluminum cannot be directly substituted in every component in a straightforward way.
A vehicle suspension includes a spindle to which a wheel hub is mounted. The spindle is mounted to a wheel carrier such as a knuckle, axle, or other component. Due to strength and heat transfer requirements, the spindle is typically made of steel or iron. Prior art spindles have previously been made as an integral forging/casting with their carrier or have been mounted to their carriers by threading or welding, for example.
Another method for mounting a spindle has been to press-fit the spindle into a bore on the wheel carrier. The interference between the spindle and the bore (i.e., the bore diameter is slightly less than the spindle diameter) creates an elastic deformation force against the spindle to retain it.
One hurdle in the possible use of aluminum castings for wheel carriers has been the lack of an easy method to attach the spindle. Prior art mounting methods have been unsuccessful due to the distinct properties of steel/iron versus aluminum, such as different thermal properties and aluminum's different elastic deformation.
SUMMARY OF THE INVENTION
The present invention adapts a press-fit method of attachment for an iron or steel spindle to an aluminum wheel carrier, resulting in overall weight savings for a vehicle. As used herein, “aluminum” includes any alloy principally comprised of aluminum.
In one aspect of the invention, a wheel assembly for a vehicle comprises a spindle and a wheel carrier. The spindle includes a shank portion and a shoulder portion. The shank portion includes a press-fit portion adjacent the shoulder portion and has a first predetermined diameter. The wheel carrier is adapted to be supported by a suspension system of the vehicle. It is comprised of aluminum and has a spindle-receiving bore therethrough. The bore has an initially-formed diameter smaller than the first predetermined diameter. The press-fit portion is press-fit into the bore. The difference between the initially-formed diameter and the first predetermined diameter is sufficiently large that the press-fit portion is surrounded by a deformation zone having a radial thickness of at least 10 microns. In one preferred embodiment, this deformation zone is comprised of both plastically and elastically deformed aluminum.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1
is an exploded, perspective view of a portion of a suspension system including a wheel carrier and spindle.
FIG. 2
is a side view of a prior art spindle mounted to a knuckle.
FIG. 3
is a side, partial cross section of a spindle of the present invention prior to press-fitting onto a wheel carrier.
FIG. 4
is a side, partial cross section of the spindle of
FIG. 3
after press-fitting.
FIG. 5
is a side, partial cross section of a press-fit spindle with a supplemental threaded nut.
FIG. 6
is a side, partial cross section of an alternative embodiment of a press-fit spindle with a supplemental threaded nut.
FIG. 7
is a side, partial cross section of an alternative embodiment of a press-fit spindle with a bolt threaded into the spindle for supplemental attachment.
FIG. 8
is a perspective view of a sleeve insert used in alternative embodiment.
FIGS. 9
,
10
, and
11
, are side, partial cross sections of spindle mounting using various embodiments of sleeve inserts.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
Referring to
FIG. 1
, a suspension system
10
includes a dead axle
11
having a wheel carrier
12
mounted thereto. Wheel carrier
12
supports a spindle
13
. A wheel hub
14
is mounted to spindle
13
by means of a grease seal
15
, bearings
16
and
17
, an adjusting nut
18
, a nut retainer
19
, a cotter pin
20
, and a grease cap
21
. The mounting of the spindle must be sufficiently robust to absorb the road loads through the wheels and distribute them to the suspension system.
FIG. 2
shows a prior art steel knuckle
24
mounted by ball joints to an axle. A steel spindle
25
is attached to knuckle
24
via a collar
26
on knuckle
24
. Spindle
25
may have provisions for bolting it to knuckle
24
or the two may be welded or press-fit together, for example. Spindle
25
has a threaded end
27
for retaining a wheel hub.
In prior art mounting of spindles by press-fitting into a bore in an iron or steel wheel carrier, the elasticity of the wheel carrier facilitated the connection. Since the deformation was elastic, the spindle could even be removed and replaced with good retention. However, elastic deformation of aluminum is so slight that insufficient interference could be created to provide a secure locking of the spindle.
The present invention goes beyond elastic deformation of the zone surrounding the bore. Instead, an interference amount is selected that creates a plastically deformed zone of predetermined thickness along with an elastically deformed zone. Plastic deformation advantageously hardens the contacting aluminum while maintaining sufficient retention forces against the spindle.
FIG. 3
shows a spindle
30
which is made of ferrous material, such as steel or iron. A wheel carrier
31
comprised of aluminum (e.g., an aluminum alloy) is shown in cross section to have a spindle-receiving bore
32
. Spindle
30
is comprised of a shoulder
33
and then a shank having a press-fit portion
34
, a wheel mount portion
35
, and a threaded end
36
. Press-fit portion
34
has a first predetermined diameter d
1
and bore
32
has an initial diameter d
2
which is smaller than first predetermined diameter d
1
. Upon insertion of spindle
30
into bore
32
, the difference in diameters creates an interference between press-fit portion
34
and the portion of wheel carrier
31
surrounding bore
32
.
FIG. 4
shows spindle
30
after being driven into bore
32
until shoulder
33
contacts wheel carrier
31
. Press-fit portion
34
has plastically deformed wheel carrier
31
to create a cylindrical deformation zone
37
. To create an appropriately sized deformation zone
37
, the difference in diameters is preferably in the range of about 20 microns or more. This creates a plastic deformation zone having a thickness of at least about 3 microns. Thus, the total deformation zone consists of both a plastic deformation region and an elastic deformation region. Plastic deformation corresponds to the increased diameter of bore
32
if spindle
30
were to be removed after deformation.
If desired, the axial retention of the spindle can be further improved as shown in
FIG. 5
by adding an intermediate threaded portion
40
on spindle
30
and engaging a nut
41
such that spindle
30
is clamped to wheel carrier
31
between nut
41
and shoulder
33
.
In an embodiment shown in
FIG. 6
, shoulder
42
is located at the intermediate portion of spindle
30
. In this embodiment, spindle
30
is press-fit into wheel carrier
31
in a direction opposite to that shown in FIG.
3
. Axial retention can again be supplemented using a second threaded end
43
engaged by a nut
44
.
FIG. 7
shows an alternative embodiment of the supplemental attachment using a bolt. Spindle
30
includes an axial threaded bore
38
as shown. A bolt
48
and washer
49
are fastened to spindle
30
to supplementally clamp spindle
30
to wheel carrier
31
between shoulder
42
and washer
49
.
In another alternative embodiment, the present invention employs a non-aluminum insert
45
shown in FIG.
8
. Preferably, insert
45
is made of steel, iron or sintered material. Insert
45
is placed within the bore in the wheel carrier and the spindle is then press-fit against the insert. Insert
45
includes a sleeve
46
and a collar
47
. Sleeve
46
has an inside diameter corresponding to the desired interference as already described. The outside diameter of sleeve
46
corresponds to the diameter of an enlarged bore in the wheel carrier. Collar
47
serves to keep sleeve
46
from being ejected from the bore during press-fitting of the spindle.
As shown in
FIG. 9
, after press-fitting into sleeve
46
, deformation of sleeve
46
can still result in plastic deformation of aluminum wheel carrier
31
. This embodiment can also be supplemented with threaded portion and nut
41
, if, desired.
FIG. 10
shows an alternative embodiment of an insert
50
which is molded in place over aluminum wheel carrier
31
. A plurality of recesses
51
are formed with an increased diameter within a bore having a diameter sized to receive insert
50
. Steel, iron, or sinter is molded in place to form fingers
52
occupying recesses
51
and a sleeve
53
having an interfering diameter with spindle
30
. Insert
50
may also include collars
54
and
55
. The radial thickness of sleeve
53
can be kept small so that aluminum wheel carrier
31
plastically deforms or can be made large enough that its own elastic deformation absorbs all the interference.
Yet another alternative embodiment is shown in
FIG. 11. A
threaded insert
56
includes threads
57
on its outer surface. The bore in wheel carrier
31
includes matching threads
58
. Insert
56
is threaded into wheel carrier
31
prior to press-fitting spindle
30
into the insert.
Claims
- 1. A wheel assembly for a vehicle, comprising:a spindle including a shank portion and a shoulder portion, said shank portion including a press-fit portion adjacent said shoulder portion and having a first predetermined diameter; and a wheel carrier adapted to be supported by a suspension system of said vehicle, said wheel carrier comprised of aluminum and having a spindle-receiving bore therethrough, said bore having an initially-formed diameter smaller than said first predetermined diameter; wherein said press-fit portion is press-fit into said bore, and wherein a difference between said initially-formed diameter and said first predetermined diameter is sufficiently large that said press-fit portion is surrounded by a deformation zone having a radial thickness of at least 10 microns.
- 2. The wheel assembly of claim 1 wherein said deformation zone is comprised of plastically-deformed aluminum.
- 3. The wheel assembly of claim 2 wherein said shank portion further includes a threaded portion, said wheel assembly further comprising a fastener engaging said threaded portion to clamp said aluminum wheel carrier between said fastener and said shoulder portion.
- 4. The wheel assembly of claim 1 wherein said shank portion further includes a threaded portion, said wheel assembly further comprising a fastener engaging said threaded portion to clamp said aluminum wheel carrier between said fastener and said shoulder portion.
- 5. The wheel assembly of claim 1 wherein said spindle is comprised of steel.
- 6. The wheel assembly of claim 1 wherein said aluminum wheel carrier further comprises a sleeve defining said spindle-receiving bore, said sleeve being substantially non-aluminum.
- 7. The wheel assembly of claim 6 wherein said sleeve includes a shoulder bearing against said aluminum wheel carrier.
- 8. The wheel assembly of claim 7 wherein said sleeve has cylindrical inside and outside surfaces and wherein said aluminum wheel carrier adjacent said outside cylindrical surface is plastically deformed by said press-fit of said spindle into said sleeve.
- 9. The wheel assembly of claim 6 wherein said shank portion further includes a threaded portion, said wheel assembly further comprising a fastener engaging said threaded portion to clamp said aluminum wheel carrier between said fastener and said shoulder portion.
- 10. A wheel assembly for a vehicle, comprising:a spindle including a shank portion and a shoulder portion, said shank portion including a press-fit portion adjacent said shoulder portion and having a first predetermined diameter; a wheel carrier adapted to be supported by a suspension system of said vehicle, said wheel carrier comprised of aluminum and having a sleeve-receiving bore therethrough; and a sleeve formed of a non-aluminum metal and integrally molded over said sleeve-receiving bore of said aluminum wheel carrier, said sleeve having a spindle-receiving bore therethrough, said spindle-receiving bore having a second predetermined diameter which is slightly less than said first predetermined diameter; wherein said press-fit portion of said spindle is received in said spindle-receiving bore of said sleeve in an interference fit therewith.
- 11. The wheel assembly of claim 10 wherein said sleeve is cast onto said aluminum.
- 12. A wheel assembly for a vehicle, comprising:a spindle including a shank portion and a shoulder portion, said shank portion including a press-fit portion adjacent said shoulder portion and having a first predetermined diameter; a wheel carrier adapted to be supported by a suspension system of said vehicle, said wheel carrier comprised of aluminum and having a threaded sleeve-receiving bore therethrough; and a sleeve formed of a non-aluminum metal and having a threaded outer surface which is threadably secured to said threaded sleeve-receiving bore of said aluminum wheel carrier, said sleeve having a spindle-receiving bore therethrough, said spindle-receiving bore having a second predetermined diameter which is slightly less than said first predetermined diameter; wherein said press-fit portion of said spindle is received in said spindle-receiving bore of said sleeve in an interference fit therewith.
- 13. A wheel assembly for a vehicle, comprising:a steel spindle including a shank portion and a shoulder portion, said shank portion including a press-fit portion adjacent said shoulder portion and having a first predetermined diameter; and an aluminum wheel carrier adapted to be supported by a suspension system of said vehicle, said aluminum wheel carrier having a spindle-receiving bore therethrough, said spindle-receiving bore having an initially-formed diameter smaller than said first predetermined diameter of press-fit portion of said spindle in the range of about 20 microns or more; wherein when said press-fit portion of said spindle is press-fit into said spindle-receiving bore of said aluminum wheel carrier the difference between said initially-formed diameter and said first predetermined diameter creates a plastic deformation zone of plastically-deformed aluminum having a thickness of at least about 3 microns.
- 14. The wheel assembly of claim 13 wherein said shank portion further includes a threaded portion, said wheel assembly further comprising a fastener engaging said threaded portion to clamp said aluminum wheel carrier between said fastener and said shoulder portion.
- 15. The wheel assembly of claim 13 wherein said aluminum wheel carrier further comprises a sleeve defining said spindle-receiving bore, said sleeve being substantially non-aluminum.
- 16. The wheel assembly of claim 15 wherein said sleeve includes a shoulder bearing against said aluminum wheel carrier.
- 17. The wheel assembly of claim 16 wherein said sleeve has cylindrical inside and outside surfaces and wherein said aluminum wheel carrier adjacent said outside cylindrical surface is plastically deformed by said press-fit of said spindle into said sleeve.
- 18. The wheel assembly of claim 15 wherein said shank portion further includes a threaded portion, said wheel assembly further comprising a fastener engaging said threaded portion to clamp said aluminum wheel carrier between said fastener and said shoulder portion.
US Referenced Citations (20)