U.S. patent number RE36,270 [Application Number 08/847,463] was granted by the patent office on 1999-08-17 for center bearing assembly including support member containing rheological fluid.
This patent grant is currently assigned to Dana Corporation. Invention is credited to James A Duggan.
United States Patent |
RE36,270 |
Duggan |
August 17, 1999 |
Center bearing assembly including support member containing
rheological fluid
Abstract
A center bearing assembly includes a roller bearing adapted to
receive and rotatably support a coupling shaft and a bracket
adapted to be secured to a vehicle frame. A support member is
provided which supports the roller bearing within the bracket. The
support member includes a bladder formed of an elastomeric
material. The bladder contains a rheological fluid which exhibits a
significant change in its ability to flow or shear upon the
application of an appropriate energy field. Preferably, the bladder
contains a magneto-rheological magnetic fluid. By varying the power
supplied to an electromagnetic located adjacent the bladder, the
vibration dampening characteristics of the support member may be
varied depending upon the operating conditions of the vehicle.
Inventors: |
Duggan; James A (Temperance,
MI) |
Assignee: |
Dana Corporation (Toledo,
OH)
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Family
ID: |
23345030 |
Appl.
No.: |
08/847,463 |
Filed: |
April 24, 1997 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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Reissue of: |
343180 |
Nov 22, 1994 |
05452957 |
Sep 26, 1995 |
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Current U.S.
Class: |
384/99; 384/535;
384/536 |
Current CPC
Class: |
F16C
27/066 (20130101); F16C 35/047 (20130101); F16C
27/04 (20130101); F16F 9/53 (20130101); B60K
17/24 (20130101); Y10T 74/2122 (20150115); F16C
19/06 (20130101); F16C 2326/06 (20130101) |
Current International
Class: |
B60K
17/22 (20060101); B60K 17/24 (20060101); F16C
27/04 (20060101); F16C 27/06 (20060101); F16C
27/00 (20060101); F16C 027/04 () |
Field of
Search: |
;384/99,535,536,581,582,8 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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342882 |
|
Nov 1989 |
|
EP |
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3908965 |
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Sep 1990 |
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DE |
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Primary Examiner: Footland; Lenard A.
Attorney, Agent or Firm: MacMillan, Sobanski & Todd,
LLC
Claims
What is claimed is:
1. A center bearing assembly adapted to rotatably support a
rotatable shaft on a vehicle frame comprising:
a rolling bearing adapted to rotatably support the rotatable
shaft;
a bracket adapted to be secured to a vehicle frame; and
a support member supporting said roller bearing within said
bracket, said support member including a bladder containing a
rheological fluid.
2. The center bearing assembly defined in claim 1 further including
means for selectively applying an energy field to said rheological
fluid.
3. The center bearing assembly defined in claim 2 wherein said
rheological fluid is a magneto-rheological fluid, and wherein said
means for applying an energy field includes an electromagnet.
4. The center bearing assembly defined in claim 2 further including
a sensor for sensing an operating condition of said vehicle, said
means for selectively applying said energy field being connected to
said sensor so as to vary said energy field in response to said
operating condition.
5. The center bearing assembly defined in claim 4 wherein said
sensor senses the radial displacement of said center bearing.
6. The center bearing assembly defined in claim 4 wherein said
sensor senses the axial displacement of said center bearing.
7. The center bearing assembly defined in claim 4 wherein said
sensor senses the radial acceleration of said center bearing.
8. The center bearing assembly defined in claim 4 wherein said
sensor senses axial acceleration of said center bearing.
9. The center bearing assembly defined in claim 4 further including
a shaft rotatably mounted within said center bearing, and wherein
said sensor senses the angular displacement of said shaft.
10. The center bearing assembly defined in claim 1 further
including a shaft rotatably mounted within said center bearing.
11. The center bearing assembly defined in claim 1 wherein said
bladder is generally annular in shape.
12. A rotatable shaft and center bearing assembly adapted to
rotatably mount the shaft to a vehicle frame, comprising:
a rolling bearing;
a shaft rotatably mounted within said roller bearing;
a bracket adapted to be secured to a vehicle frame; and
a support member supporting said roller bearing within said
bracket, said support member including a bladder containing a
rheological fluid.
13. The rotatable shaft and center bearing assembly defined in
claim 12 further including means for selectively applying an energy
field to said rheological fluid.
14. The rotatable shaft and center bearing assembly defined in
claim 13 wherein said rheological fluid is a magneto-rheological
fluid, and wherein said means for selectively applying said energy
field includes an electromagnet.
15. The rotatable shaft and center bearing assembly defined in
claim 13 further including a sensor for sensing an operating
condition of said vehicle, said means for selectively applying said
energy field being connected to said sensor so as to vary said
energy field in response to said operating condition.
16. A vehicle comprising:
a frame;
a rolling bearing;
a shaft rotatably mounted within said roller bearing;
a bracket secured to said frame; and
a support member supporting said roller bearing within said
bracket, said support member including a bladder containing a
rheological fluid.
17. The vehicle defined in claim 16 further including means for
selectively applying an energy field to said rheological fluid.
18. The vehicle defined in claim 17 wherein said rheological fluid
is a magneto-rheological fluid, and wherein said means for
selectively applying said energy field includes an
electromagnet.
19. The vehicle defined in claim 17 further including a sensor for
sensing an operating condition of said vehicle, said means for
selectively applying said energy field being connected to said
sensor so as to vary said energy field in response to said
operating condition. .Iadd.
20. A center bearing assembly adapted to rotatably support a
rotatable shaft on a vehicle frame comprising:
a roller bearing adapted to rotatably support the rotatable
shaft;
a bracket adapted to be secured to a vehicle frame; and
a support member supporting said roller bearing within said
bracket, said support member containing a rhelogical fluid for
modifying the relative movement between said roller bearing and
said bracket. .Iaddend..Iadd.21. The center bearing assembly
defined in claim 20 wherein said support member includes a cavity
containing said rhelogical fluid. .Iaddend..Iadd.22. The center
bearing assembly defined in claim 21 wherein said support member
defines an annular shaped cavity. .Iaddend..Iadd.23. The center
bearing assembly defined in claim 21 further including means for
selectively applying an energy field to said rheological fluid.
.Iaddend..Iadd.24. The center bearing assembly defined in claim 23
wherein said rheological fluid is a magneto-rheological fluid, and
wherein said means for applying an energy field includes an
electromagnet. .Iaddend..Iadd.25. The center bearing assembly
defined in claim 23 further including a sensor for sensing an
operating condition of said vehicle, said means for selectively
applying said energy field being connected to said sensor so as to
vary said energy field in response to said operating
condition. .Iaddend..Iadd.26. The center bearing assembly defined
in claim 23 wherein said sensor senses the radial displacement of
said center bearing. .Iaddend..Iadd.27. The center bearing assembly
defined in claim 23 wherein said sensor senses the axial
displacement of said center bearing. .Iaddend..Iadd.28. The center
bearing assembly defined in claim 23 wherein said sensor senses the
radial acceleration of said center bearing. .Iaddend..Iadd.29. The
center bearing assembly defined in claim 23 wherein said sensor
senses the axial acceleration of said center bearing.
.Iaddend..Iadd.30. The center bearing assembly defined in claim 23
further including a shaft rotatably mounted within said center
bearing, and wherein said sensor senses the angular displacement of
said shaft. .Iaddend.
Description
BACKGROUND OF THE INVENTION
The invention relates in general to bearings for supporting shafts
for rotation and in particular to an improved structure for a
center bearing assembly for rotatably supporting an intermediate
portion of a vehicle drive line or coupling shaft assembly.
In most rear wheel drive vehicles, a source of rotational energy,
such as an internal combustion or diesel engine, is located near
the front of the vehicle. The engine is connected by means of a
drive line to rotate one or more driven wheels located near the
rear of the vehicle. The drive line typically extends between a
transmission, which is connected to the engine, and a differential,
which is connected to the driven wheels. In some vehicles, the
distance separating the transmission and the differential is
relatively short. In these vehicles, the drive line is composed of
a single tube, usually referred to as the drive shaft. In other
vehicles, the distance separating the transmission and the
differential is relatively long, making the use of a single drive
shaft impractical. In these vehicles, the drive line is composed of
a drive shaft and one or more coupling shafts. The coupling shafts
are connected to the drive shaft (and to each other) by universal
joints.
Drive lines which are composed of a drive shaft and one or more
coupling shafts require the use of one or more intermediate
resilient support structures, which are generally referred to as
center bearing assemblies. A typical center bearing assembly
includes an annular roller bearing within which the coupling shaft
is rotatably supported. The roller bearing itself is disposed
within a generally annular resilient support member. The resilient
support member is, in turn, disposed within a relatively rigid,
generally U-shaped bracket which is secured to the lower surface of
a cross member extending between the side rails of the vehicle
frame.
The resilient support member is provided to reduce vibrations of
the drive line in the vicinity of the center bearing assembly and
to prevent such vibrations from being transmitted to the vehicle
frame. In the past, the resilient support member has been formed
from an elastomeric material, such as rubber. Under most vehicle
operating conditions, known rubber support members are effective in
substantially reducing the transmission of vibrations for the drive
line to the vehicle frame. However, the vibration dampening
characteristics of such known support members, which depend upon
the specific material and the particular configuration thereof,
remain constant regardless of the vehicle operating conditions.
Accordingly, the vibration dampening characteristics of known
support members can be optimized only for a single set of operating
conditions. The vibrations generated by the drive line, on the
other hand, constantly change with changes in the operating
conditions of the vehicle. As a result, these support members may
not provide optimum vibration dampening of vibrations under varying
operating conditions. It would, therefore, be desirable to provide
an improved structure for a center bearing assembly which includes
a support member having vibration dampening characteristics which
can be adjusted in accordance with the changing operating
conditions of the vehicle.
SUMMARY OF THE INVENTION
The invention relates to a center bearing assembly adapted to
rotatably support a rotatable shaft on a vehicle frame. The center
bearing assembly includes an annular roller bearing, which is
adapted to receive and rotatably support the rotatable shaft, and a
bracket which adapted to be secured to the vehicle frame. A support
member is provided which supports the roller bearing within the
bracket. The support member includes a bladder which is formed of
an elastomeric material and which contains a rheological fluid. The
term "rhelogical fluid" is used herein to describe any fluid which
exhibits a significant change in its ability to flow, or shear,
upon the application of an appropriate energy field, such as
electrical or magnetic fields. Thus, the novel construction of the
invention provides an effective center bearing assembly support
member having vibration dampening characteristics which may be
varied with the changing operating conditions of the vehicle.
Various objects and advantages of this invention will become
apparent to those skilled in the an from the following detailed
description of the preferred embodiment, when read in light of the
accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a front elevational view of a center bearing assembly in
accordance with this invention.
FIG. 2 is a cross sectional view of the center bearing assembly
taken along line 2--2 of FIG. 1.
FIG. 3 is a block diagram of a control system for the center
bearing assembly illustrated in FIGS. 1 and 2.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring now to the drawings, there is illustrated in FIGS. 1 and
2 a center bearing assembly, indicated generally at 10, in
accordance with this invention. As is well known in the art, the
center bearing assembly 10 is adapted to rotatably support a
rotatable shaft 11 or similar component of a multiple piece vehicle
drive line on the lower surface of a cross member 12 or other
portion of a frame for a vehicle. To accomplish this, the cross
member 12 is formed having a pair of threaded apertures 13 and 14
for securing the center bearing assembly 10 thereto, in a manner
which will be described in detail below. The general structure and
operation of the center bearing assembly 10 is well known in the
art and, for the sake of brevity, will not be discussed in detail
herein. U.S. Pat. No. 4,392,694 to Reynolds, owned by the assignee
of this invention, discloses the general structure and operation of
center bearing assemblies, and the disclosure thereof is
incorporated herein by reference.
The center bearing assembly 10 includes a bracket, indicated
generally at 20. The bracket 20 includes a generally annular body
portion 21 and a pair of opposed, outwardly extending leg portions
22 and 23. As best shown in FIG. 2, the body portion 21 of the
bracket 20 is preferably formed having a substantially U-shaped
cross sectional shape for providing strength thereto. The leg
portions 22 and 23 may be formed integrally with the body portion
21 as shown, or alternatively may be secured to the body portion 21
by welding or any other suitable method. Respective apertures 22a
and 23a are formed through the ends of the leg portions 22 and 23.
The apertures 22a and 23a formed through the leg portions 22 and 23
of the bracket 20 are spaced apart from one another by the same
distance as the apertures 13 and 14 formed in the cross member 12.
Thus, as will be explained in detail below, the apertures 22a and
23a can be aligned with the apertures 13 and 14 to permit the
bracket 20 to be secured to the cross member 12 of the vehicle
frame.
A reinforcing bar 24 is disposed between the bracket 20 and the
cross member 12. The reinforcing bar 24 includes a central body
portion 25 and a pair of end portions 26 and 27. The central body
portion 25 is formed having a 25 recess 25a, within which a portion
of the annular body portion 21 of the bracket 20 extends.
Respective apertures 26a and 27a are formed through the end
portions 26 and 27 of the reinforcing bar 25. The apertures 26a and
27a formed through the reinforcing bar 25 are spaced apart from one
another by the same distance as the apertures 13 and 14 formed in
the cross member 12. Thus, the apertures 26a and 27a can be aligned
with the apertures 22a and 23a and with the apertures 13 and 14 to
permit the bracket 20 to be secured to the cross member 12 of the
vehicle frame by suitable threaded fasteners 30. The threaded
fasteners 30 extend through the aligned apertures 22a, 26a, and 13
and through the aligned apertures 23a, 27a, and 14 to secure the
bracket 20 and reinforcing bar 24 to the cross member 12.
The center bearing assembly 10 further includes a support member,
indicated generally at 30. As best shown in FIG. 2, the support
member 30 is embodied as a bladder 31 formed from a flexible
elastomeric material. The bladder 31 is generally annular in shape,
having an outer circumferential surface which is secured to an
inner circumferential surface of the body portion 21 of the bracket
20. The bladder 31 may be molded directly to the bracket 20, or may
be secured thereto in any other suitable manner, such as with an
adhesive. The inner circumferential surface of the bladder 31
defines an enlarged axially extending opening 32 formed through the
center thereof, the purpose of which will be explained below. An
annular cavity 31a is defined within the bladder 31. The annular
cavity 31a of the bladder 31 is filled with a suitable rheological
fluid 33.
As mentioned above, the term "rheological fluid" as used herein
refers to a fluid which exhibits a significant change in its
ability to flow or shear upon the application of an appropriate
energy field. In the preferred embodiment, the rheological fluid is
a magneto-rheological (MR) fluid, which is responsive to the
presence of a magnetic field for changing is ability to flow or
shear. MR fluids are formed of magnetizable particles, such as
carbonyl iron, in a fluid carrier, such as a silicone oil. When
exposed to a magnetic field, the particles align and reduce the
ability of the fluid to flow. The shear resistance of the MR fluid
is a function of the magnitude of the applied magnetic field. MR
fluids are preferred for use in this invention because they are
capable of generating relatively high fluid shear stresses and can
be controlled using power supplies which are normally available in
vehicles. TRW MR fluid, which is commercially available from TRW,
Inc., is an example of one known rheological fluid which has been
found suitable for use in this invention. However, other
rheological fluids can also be used in accordance with this
invention. For example, electro-rheological (ER) fluids, which are
responsive to the presence of an electrical field (such as voltage)
may also be used.
Means are provided for selectively generating and applying an
energy field to the rheological fluid. The specific nature of this
means will depend upon the particular type of rheological fluid is
selected for use. In the preferred embodiment, where the
rheological fluid is an MR fluid, the means for selectively
generating an energy field can include one or more electromagnetic
coils 35 provided proximate the bladder 32 containing the MR fluid
33. The electromagnetic coils 35 may be arranged in any manner such
that when energized, a magnetic field is applied to the MR fluid
33. The electromagentic coils 35 are preferably arranged so that
the applied magnetic field is generally uniform over the interior
of the bladder 32 containing the MR fluid 33. The electromagnetic
coils 35 are preferably circumferentially embedded in or otherwise
supported on the support member 30. The coils 35 are connected to a
power supply through electrical conductors (not shown). By varying
the magnitude of the power supplied to the electromagnetic coils
35, the strength of the magnetic field applied to the MR fluid 33
can be varied. As a result, the resistance to flow or shear of the
MR fluid 33, which affects the vibration dampening characteristics
of the support member 30, can be varied. The means by which the
power supplied to the electromagnetic coils 35 is controlled is
described below.
An annular bearing seat 40 is secured within the central opening
31a of the bladder 31. The bladder 31 may be molded directly to the
bearing seat 40, or may be secured thereto in any other suitable
manner, such as with an adhesive. An annular roller bearing 50 is
mounted in the bearing seat 40. The roller bearing 50 is typically
a ball type roller bearing, but may be any suitable antifriction
bearing. One end of the rotatable shaft 11 of the vehicle drive
line is received and rotatably supported in the roller bearing
50.
As mentioned above, by varying the magnitude of the power supplied
to the electromagnetic coils 35, the vibration dampening
characteristics of the support member 30 can be changed. Such
changes are preferably effected in response to a change in one or
more of the operating conditions of the vehicle. To accomplish
this, sensors are provided for sensing one or more operating
conditions of the vehicle. Referring to FIG. 3, it can be seen that
a plurality of sensors 60, 61, and 62 can be provided for
monitoring the status of the vehicle operating conditions and for
generating electrical signals which are representative thereof. For
example, some of the vehicle operating conditions which can be
monitored by the sensors 60, 61, and 62 can include the vehicle
speed, vehicle acceleration, rotational speed of the shaft 11,
angular displacement of the shaft 11, radial acceleration of the
center bearing 50, axial acceleration of the center bearing 50,
radial displacement of the center bearing 50, and axial
displacement of the center bearing 50. If desired, however, other
operating conditions of the vehicle may also be sensed and used to
control the vibration dampening characteristics of the support
member 30.
Each of the sensors 60, 61, and 62 is connected to an electronic
circuit 70. The electronic control circuit 70, which may be
embodied as any conventional microprocessor or similar computing
device, is programmed to continuously read the electrical signals
from the sensors 60, 61, and 62 and to generate an electrical
control signal in response to a pre-programmed algorithm. The
algorithm used by the electronic control circuit 70 can be easily
derived using known vibration data or by testing on the vehicle. In
the simplest embodiment of the invention, a single sensor 60 is
used to monitor a single vehicle operating condition. By measuring
the amount of vibration which is generated for given value of the
sensed operating conditions, a look-up table can be created which
correlates the value of the sensed operating condition with a value
for the control signal which will minimize the generation of such
vibration. The same procedure can be followed when two or more
operating conditions are sensed.
The output signal of the electronic control circuit 70 is connected
to a current driver circuit 71. The current driver circuit 71 is
conventional in the art and is provided to convert the output
signal from the controller 70 into a corresponding electrical
current. The electrical current generated by the current driver
circuit 71 is fed to the electromagentic coils 35, which generate
the magnetic field in response thereto. Thus, it can be seen that
the magnitude of the output signal generated by the electronic
control circuit 70 determines the magnitude of the electromagnetic
field generated by the electromagnetic coils 35. Consequently, the
ability of the MR fluid 33 contained in the cavity 32a of the
bladder 32 to flow or shear can be varied. The vibration dampening
characteristics of the support member 30 can, therefore, be
continuously varied according to the control algorithm and the
information provided by the sensors 60, 61, and 62.
A manual control device 80 may be directly connected to the driver
circuit 71. The manual control device 80 can allow the operator of
the vehicle to directly adjust the magnitude of the current
supplied to the electromagnetic coils 35. As a result, fine
adjustment of the vibration dampening characteristics of the
support member 30 is permitted to reduce or eliminate any remaining
vibrations transmitted to the vehicle frame. The manual control
device 80 can be embodied as a simple potentiometer or other device
which, in response to manual manipulation, generates an output
signal to the driver circuit 71. The manual control device 80 may
be used in conjunction with the sensors 60, 61, and 62 and the
electronic control circuit 70, or in lieu thereof.
Additionally, it will be appreciated that the outputs of the
sensors 60, 61 and 62 may be connected directly to the driver
electronics 71 as shown by the dotted lines in FIG. 3, thereby
eliminating the need for the electronic control circuit 70. In this
arrangement, the sensors 60, 61, and 62 can function in a manner
similar to the manual control device 80 described above, wherein
the output signals therefrom are used directly by the driver
circuit 71 to control the magnitude of the electrical current
supplied to the electromagnetic coils 35.
In accordance with the provisions of the patent statutes, the
principle and mode of operation of this invention have been
described in its preferred embodiment. However, it should be noted
that this invention may be practiced otherwise than as specifically
illustrated and described without departing from its spirit or
scope.
* * * * *