WO2009036024A1 - Magnetic suspension of a prop shaft center bearing isolator - Google Patents

Abstract

A bearing isolator for a propshaft assembly of a motor vehicle includes a isolating material having an aperture formed therein for receiving a bearing. The aperture, at least partially, defines an inner isolator surface. The isolator also includes a generally annular outer magnet portion having a generally cylindrical outer magnet outer portion, a generally cylindrical outer magnet inner portion, an outer first magnetic pole portion, and an outer second magnetic pole portion. The outer first magnetic pole portion is adjacent the outer magnet inner portion. The outer second magnetic pole portion is adjacent the outer magnet outer portion. The isolator further includes a generally annular inner magnet portion having a generally cylindrical inner magnet outer portion, a generally cylindrical inner magnet inner portion, an inner first magnetic pole portion, and an inner second magnetic pole portion. The inner first magnetic pole portion is adjacent the inner magnet outer portion.

Description

MAGNETIC SUSPENSION OF A PROP SHAFT CENTER BEARING ISOLATOR

CROSS REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority to U.S. Provisional Patent Application 60/971,050, filed September 10, 2007, the disclosure of which is incorporated by reference in its entirety.

TECHNICAL FIELD

[0002] The present disclosure relates to an isolator for a bearing of a multi-piece propshaft, and in particular to an isolator that includes an isolating material and at least two opposing magnet portions that exert a generally radially inward force upon the bearing.

BACKGROUND

[0003] A motor vehicle generally utilizes a propshaft to connect the transmission or power takeoff unit to the driving axle. Prop shafts may become rotationally unstable if operated at a rotational speed where the propshaft residual balance forces coincide with the propshaft natural bending resonance. This rotational speed is known as the critical speed. One factor influencing bending resonance is the length of the propshaft. As the length of the prop shaft increases, the bending frequency and the critical speed decrease. One known method used to increase the bending frequency of a prop shaft is to split the shaft into multiple sections connected by joints, such as a constant velocity joint. Each resulting propshaft will be shorter than a single piece prop shaft for the vehicle and have a higher bending resonance which alleviates undesired operational effects associated with reaching the critical speed (i.e. raises the resulting critical speed of each propshaft section to a speed that is higher than the prop shafts will experience in normal operation).

[0004] Multiple-section prop shafts may also be used for packaging constraints. The layout of the underbody of a motor vehicle may not allow for a completely linear one-piece propshaft from a transmission to a differential. This may occur when the pathway where a one-piece propshaft would normally connect the power take-off unit and the rear differential together may be obstructed by other underbody components, such as the fuel tank, the exhaust system, body panels, or structural framework. A multiple piece propshaft may be installed within a motor vehicle in a variety of non-linear configurations. A universal joint, such as a Cardan universal joint, may also be used to connect the multiple prop shafts together.

[0005] A center bearing may be utilized to support portions of the multiple-section prop shafts. Further, the bearing may be mounted in an isolator to reduce the translation of vibrations from the prop shafts to the vehicle chassis during driving conditions. Additionally, the center bearing isolator may also reduce shudder by limiting the transfer of higher loadings due to undesirable vibrations to the vehicle chassis or underbody.

[0006] The center bearing may also reduce axle gear whine from either the front axle or the rear axle. Although axle gear whine relates to gear mesh force, it is understood that control of the propshaft dynamics to minimize the sensitivity to gear mesh variation may also be important. In fact, the gear mesh force depends on the propshaft torsional mass moment of inertia as well as the propshaft bending resonance.

[0007] The center bearing includes an isolator that may be constructed from a polymer, membrane, or other similar material that absorbs vibration. The polymer's natural frequency is directly proportional to the load deflection curve. That is, the lower the natural frequency, the lower the load deflection curve. A low load deflection curve allows for enhanced vibration absorbing properties. However, a low load deflection curve may require a softer polymer. When a softer polymer is used, the fatigue life may be reduced when compared to a less soft polymer, thereby leading to premature center bearing failure.

[0008] Thus, there exists a need for a center bearing assembly that has the vibration absorbing properties of a softer polymer while still achieving acceptable fatigue life as the current production center bearing isolators.

BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Although the drawings represent some embodiments, the drawings are not necessarily to scale and certain features may be exaggerated, removed, or partially sectioned to better illustrate and explain the present invention. Further, the embodiments set forth herein are exemplary and are not intended to be exhaustive or otherwise limit or restrict the claims to the precise forms and configurations shown in the drawings and disclosed in the following detailed description.

[0010] FIG. 1 is a top view of a driveline system, according to an embodiment. [0011] FIG. 2 is a partial sectional top view of the propshaft illustrated in FIG. 1. [0012] FIG. 3 is a partial sectional view taken along line 3 -3 of FIG. 2, with some section graphics removed for clarity.

[0013] FIG. 4 is an alternative embodiment of the isolator of FIG. 3, taken from generally the same view as FIG. 3, with some section graphics removed for clarity.

[0014] FIG. 5 is a view of an isolator, a bearing and a shaft, taken generally along line 5-

5 of FIG. 3.

[0015] FIG. 6 is an illustration of a load deflection curve of a center bearing and an isolator including an air gap.

[0016] FIG. 7 is an illustration of a load deflection curve of a center bearing and an isolator without an air gap.

[0017] FIG. 8 is an illustration of a load deflection curve of a center bearing with a conventional isolator.

DETAILED DESCRIPTION

[0018] Exemplary illustrations are described below. In the interest of clarity, all features of an actual implementation may not described in this specification. It will of course be appreciated that in the development of any such actual illustration, numerous implementation-specific decisions must be made to achieve the developers' specific goals, such as compliance with system-related and business-related constraints that will vary from one implementation to another. Moreover, it will be appreciated that such a development effort might be complex and time-consuming, but would nevertheless be a routine undertaking for those of ordinary skill in the art having the benefit of this disclosure. [0019] FIG. 1 illustrates a driveline 20 of a vehicle (not shown). The driveline 20 includes an engine 22 that is connected to a transmission 24 and a transfer case, or power take off unit, 26. A front differential assembly 32 has a right hand front half shaft 34 and a left hand front half shaft 36, each of which are connected to a wheel 38 and deliver power to those wheels 38. The power take off unit 26 has a propeller shaft assembly 40 and a front wheel propeller shaft 42 extending therefrom. The front wheel propeller shaft 42 connects the front differential assembly 32 to the power take off unit 26. The propeller shaft assembly 40 connects the power take off unit 26 to a rear differential 44, wherein the rear differential 44 includes a rear right hand side shaft 46 and a rear left hand side shaft 48, each of which ends with a wheel 38 on one end thereof. [0020] The propeller shaft 40 also includes a joint assembly 50, a front prop shaft 52, a rear prop shaft 54, a center bearing assembly 56 and two high speed constant velocity joints 60. The center bearing assembly 56 is coupled to a vehicle underbody 64. The joint assembly 50 is attached to the underbody of the vehicle 64 and may also include a constant velocity joint to transmit torque between the front prop shaft 52 and the rear prop shaft 54. A constant velocity joint 60 may be located on the ends of the propeller shaft 40. The constant velocity joints 60 allow for transmission of constant velocities at angles which are found in everyday driving in the half shafts 52 and 54 of the vehicle.

[0021] The driveline 20 represents an all wheel drive vehicle, however it should be noted that the center bearing assembly 56 may also be used in rear wheel drive vehicles, front wheel drive vehicles, and four wheel drive vehicles.

[0022] As best seen in FIG. 2, the center bearing assembly 56 receives a shaft 70 having an axis A-A that may be connected to the rear prop shaft 54. The center bearing assembly 56 also includes a bearing 72 and a magnetic isolator 74. The bearing 72 may be selectively received by the isolator 74, and both the bearing 72 and the isolator 74 absorb vibrations from the propeller shaft 40. The isolator 74 may be bonded to the bearing 72 outer race. [0023] As best seen in FIGS. 3 and 5, the isolator 74 includes an isolator axis I-I, an isolating material 76, an inner magnet portion 78, an annular portion 80, and an outer magnet portion 82. In the embodiment illustrated, the annular portion 80 is interposed between the inner magnet portion 78 and the outer magnet portion 82.

[0024] In the embodiment illustrated, the bearing 72 includes a bearing axis B-B, an inner race 84, an outer race 86, and a plurality of rollers 88. The outer race 86 includes an outer race surface 90. The isolator 74 may be bonded to the bearing 72 outer race surface 90. [0025] The area around center bearing assembly 56 may reach elevated temperatures due to the exhaust system (not shown) of the vehicle or other operational conditions. Thus, the isolating material 76 of the isolator may be constructed from a material that exhibits suitable heat resistant characteristics, such as, but not limited to, nitrile and hydrogenated nitrile butadiene rubber (HNBR).

[0026] Moreover, the magnet portions 78 and 82 may be constructed from a magnetic alloy that may be heat resistant against elevated temperatures, and may also be constructed from materials such as, but not limited to, rare earth magnetic materials and Alnico. Indeed, the magnet portions 78 and 82 may be constructed from an alloy that includes a Curie point that will allow for the retention of the alloy's ferromagnetic ability up to temperatures of about 800°C.

[0027] The bearing 72 may be any center bearing that may be typically utilized in a multiple piece propeller shaft, or other suitable bearings. A layer of isolating material may also be included with the bearing 72. However, it is understood if the bearing 72 is used in conjunction with the isolator 74, the layer of isolating material may be omitted. [0028] FIG. 3 is a partially cross sectioned view of the isolator 74, with the bearing 72 included. Isolator 74 may also include a mounting bracket 96 attached to a portion of the vehicle body 64 that allows for attachment of the isolator 74 to the underbody of a vehicle. Alternatively, the isolator 74 is restrained by the bracket 96 while the isolator 74 does not contact the vehicle body 64. The bracket 96 forms a portion of a restraining portion of the vehicle that restrains the isolator 74.

[0029] The isolating material 76 includes a generally cylindrical inner surface 92 that defines an aperture 94 therethrough for receiving the bearing 72, a generally cylindrical isolator outer surface 98, a first inner annular portion 100, an inner portion 102, an outer portion 104, a first annular cavity 106, a plurality of second annular cavities 108, a generally annular first side portion 110, a generally annular second side portion 112, a third annular cavity 114 and a second inner annular portion 116. While the portions 100, 102, 104, 110, 112, 116 are shown generally with lines to illustrate the boundaries between the portions, the isolator 74 may be formed by molding the portions 100, 102, 104, 110, 112, 116 simultaneously as a single piece with the magnet portions 78, 82 and the annular portion 80 interposed within. The portions 100, 102, 104, 110, 112, 116 may be bonded to the magnet portions 78, 82 during forming, as desired. The annular portion 80 may be an empty space filled with a pressurized gas or air, alternatively, the annular portion 80 may also be an isolating material (of material 76 or a different isolating material) that is bonded to at least a portion of the interior of the third annular cavity 114.

[0030] The second magnet portion 82 is positioned within the first annular cavity 106. In the embodiment illustrated, the inner magnet portion 78 includes a plurality of inner magnet sections 118 which are each positioned within one of the plurality of second annular cavities 108. The second magnet portion 82 includes a generally cylindrical outer magnet outer portion 120, a generally cylindrical outer magnet inner portion 122, a first outer magnet surface 124, and a second outer magnet surface 126. The second magnet portion 82 includes an outer first magnetic pole portion 130 adjacent the outer magnet inner portion 122 and an outer second magnetic pole portion 132 adjacent the outer magnet outer portion 120. [0031] The inner magnet sections 118 are at least two generally circumferentially spaced magnets disposed within the isolating material 76. Each inner magnet section 118 includes a generally cylindrical inner magnet outer portion 140, a generally cylindrical inner magnet inner portion 142, a first inner magnet surface 144, and a second inner magnet surface 146. Each inner magnet section 118 also includes an inner first magnetic pole portion 150 adjacent the inner magnet outer portion 140, and an inner second magnetic pole portion 152 adjacent the inner magnet inner portion 142.

[0032] The outer first magnetic pole portion 130 is the same pole as the inner first magnetic pole portion 150. That is, both are North or South (positive or negative) pole of the magnet portions 78, 82. Similarly, the outer second magnetic pole portion 132 is the same pole as the inner second magnetic pole portion 152. Accordingly, since the outer first magnetic pole portion 130 faces the inner first magnetic pole portion 150 at a sufficiently close distance, the inner magnet sections 118 are repelled radially inwardly by the second magnet portion 82. This inward radial repelling force exerts a radially inward force F on the inner portion 102. Also, this repelling force exerts a tensile force within each of the first side portion 110 and the second side portion 112.

[0033] The radially inward force F is transferred to the outer race surface 90 as well. It should be noted that while FIG. 3 illustrates eleven inner magnet sections 118, a plurality of generally opposing magnets may be used.

[0034] In the illustration as shown in FIG. 3, the inner magnet sections 118 extend in part along an inner circumferential path R2, where the path R2 is illustrated by a dotted line. That is, the inner magnet portion 78 is segmented while retaining a generally cylindrical configuration. The outer magnet portion 82 extends along the entire circumference of an outer circumferential path Rl. Both of circumferential paths Rl and R2 are concentric with respect to the axis I-I of the isolator 74. Each of the magnets 78 and 82 are formed concentrically and are coaxially aligned with the axis I-I of the isolator 74. FIG. 3 illustrates the inner magnet portion 78 as segmented and the outer magnet portion 82 extending along the entire circumference. However, it should be noted that the inner magnet portion 78 may extend along the entire circumference of the circumferential path R2, and the outer magnet portion 82 may be segmented instead. Moreover, as illustrated in FIG. 4 and discussed in greater detail below, both of the inner magnet portion 78 and the outer magnet portion 82 may be segmented.

[0035] The annular portion 80 may be a volume of space, such as air or a gas, interposed between the outer magnet portion 82 and the inner magnet portion 78. Alternatively, the annular portion 80 may be an isolating material with desirable isolation properties. Depending upon the amount of vibration isolating characteristics that are desired in a specific application a width WA, as best seen in FIG. 5, of the annular portion 80 may vary between about one millimeter (1.0 mm) and five millimeters (5.0 mm).

[0036] FIG. 3 illustrates the annular portion 80 extending along the entire circumference of a circumferential path RA. However, it is understood the annular portion 80 may extend along only a portion of a circumferential path RA that may be concentric with respect to the center axis A of the aperture 94. It should be noted that while FIGS. 2 and 3 illustrate the isolator 74 with the annular portion 80 interposed between the outer magnet portion 82 and the inner magnet portion 78, an isolator without an annular portion 80 may be used. However, the annular portion 80 may result in improved isolation characteristics when compared to the isolator 74 without the annular portion 80, as discussed in greater detail below.

[0037] FIG. 5 is a partially cross sectional plan view of the isolator 74, the bearing 72 and the shaft 70. The isolating material 76 includes the outer portion 104 and the inner portion 102. The inner portion 102 may be adhered to the inner surface 92 of the bearing 72. The outer portion 104 is located radially outwardly from both of the magnets 78 and 82. The side portions 110, 112 of the isolator 74 are located on each side of the isolator 74, outboard of the magnets 78 and 82. As discussed in greater detail below, the side portions 110, 112 may be in tension when the isolator 74 is not installed. It should be noted that side portions 110, 112 are annular and extend around axis I-I.

[0038] Operation of the isolator 74 in conjunction with the bearing 72 and the shaft 70 will now be explained in detail. To describe the operation of the isolator 74 in terms of operating the shaft 70, as the shaft 70 rotates, various operational forces act upon the shaft 70. Some of these operational forces (such as 1. the vehicle wheels 38 being forced upward generally perpendicular to the axis I-I, such as when the vehicle maneuvers over a speed bump; or 2. vibrations resulting from imbalances in the shaft 70) may result in an outside force urging the shaft 70 towards a direction D (FIG. 3). That is, the axis A-A of the shaft 70 (and the axis B-B of the bearing 72), may move in the direction D relative to the axis I-I of the isolator 74.

[0039] FIGS. 3 and 5 illustrate the shaft 70, the bearing 72, and the isolator 74 in a generally concentric configuration before operation of the driveline 20. That is, the axes A- A, B-B, and I-I are generally co-axial. As the shaft 70 and bearing 72 move generally in the direction of the arrow D, a first segment 160 of the isolator 74 is compressed relative to the configuration of FIG. 3. Further, a second segment 162 of the isolator 74 is generally in tension. More specifically, the portions 102, 104, 80, 100, and 116 of segment 160 are compressed, while the portions 110, 112 of the second segment 164 are placed further in tension. Both the compression of portions of the isolator 74 in segment 160 and tension of portions of the isolator 74 within the second segment 162 will urge the axis A-A of the shaft 70 toward the axis I-I of the isolator 74 while dampening the movement of the shaft 74 relative to the body 64 and bracket 96. Since the portions 110, 112 of the second segment 164 are placed further in tension and the inner surface 92 of the isolator 74 is bonded to the outer race surface 90, the portions 110, 112 resist movement of the shaft 70 in any radial direction.

[0040] Similarly, when the shaft 70 axis A-A moves towards the direction E, which is opposite the direction D, the inner magnet sections 118 within the segment 162 may move toward the second magnet portion 82. The force F from the interaction between the second magnet portion 82 and the inner magnet sections 118 within the segment 162 will also tend to urge the shaft 70 towards the configuration of FIG. 3 (where the isolator 74 and the shaft 70 are concentric). Additionally, the side portions 110, 112 of the isolator 74 may exert the force F upon the isolator 74, and more specifically, along the isolator outer surface 98. While the inner magnet sections 118 are illustrated in FIGS. 3 and 5 as spaced circumferentially at generally equal radial distances from the axis I-I, the inner magnet sections 118 may not be spaced but rather in contact.

[0041] In the embodiment illustrated, the side portions 110, 112 of the isolator 74 are always in tension, even without the repulsive force of the outer magnet portion 82 and the inner magnet portion 78, when the isolator 74 is constructed. That is, the side portions 110, 112 may be in tension during forming of the isolator 74 and subsequent bonding of the isolator 74 to the outer race 86. When the isolating material 76 of the isolator 74 is molded, the two magnets 78 and 82 cause the side portions 110, 112 to be permanently in tension. Even if the two magnets 78 and 82 were replaced by a material that did not exhibit magnetic properties, the side portions 110, 112 would still be in tension due to the molded-in stresses and/or the tensile loading of bonding the outer race surface 90 to the inner surface 92 of the isolator 74. However, the inner portion 102 may be either neutral, or in compression during operation of the driveline 20. This resistance to deflection continues as the bearing 72 moves in direction D, or in any other radial direction as well.

[0042] FIGS. 6, 7 and 8 illustrate estimated load deflection curves. FIG. 6 is a load deflection curve of the bearing 72 and the isolator 74 with the annular portion 80. FIG. 7 is a load deflection curve of the bearing 72 and the isolator 74 without the annular portion 80. FIG. 8 is a load deflection curve of the bearing 72 with a conventional isolator made entirely of a isolating material with no magnet portions. An isolator with a load deflection curve that includes a low amount of deflection when a load is applied is usually preferred. That is, a load deflection curve that is as close to the zero value of the deflection axis may be desired. This may be because a small amount of deflection when a load is applied to the isolator 74 results in less deflection being translated from the propeller shaft 40 to the vehicle chassis. More specifically, because the deflection is absorbed by the isolator 74 the deflection can not be exerted upon the vehicle chassis.

[0043] The force F may be exerted in a radially inwards direction upon the inner surface 92 of the isolator 74 and the bearing 72. That is, when the bearing 72 is used in conjunction with the isolator 74, the end result may be an improved load deflection curve when compared to the load deflection curve of the bearing and a conventional isolator, as seen in FIG. 8. This is because the force F generated from magnets 78 and 82 of the isolator 74 is opposite to and dampens the vibrations from the bearing 72, as seen in FIG. 5. More specifically, the bearing 72 transmits vibrations from the propeller shaft 40 in a radially outward direction, as seen in FIGS. 3 and 4 as a force FB, and the force F from the isolator 74 may be directed radially inwardly. Thus, the force F from the isolator 74 counteracts with the force FB from the bearing 72 because each of the forces act in opposite directions.

[0044] A vertical line 130, as seen in all of FIGS. 6-8, represents the isolator 74 when at least a portion of the isolating material 76 may be nearly or fully compressed. That is, as the outer race 86 of the bearing 72 moves generally in the radial direction D (FIG. 3) with the respect to the axis I-I of the isolator 74, a portion of the isolating material 76 and annular portion 80 within the isolator 74, such as within the first segment 160 (FIG. 3) may be fully compressed such that the isolator 74 will transmit a force through the isolator outer surface 98 to the vehicle underbody 64 at the second segment 164. At the vertical line 130 the load deflection curve slope changes due to the high compression of the isolator 74. This may be because when the isolator 74, and in particular the inner portion 102, is nearly or completely compressed, the maximum amount of the force F is usually exerted upon the bearing 72. When the maximum amount of the force F is exerted upon the bearing 72, any additional force FB from the bearing 72 is typically not absorbed by the inner portion 102 of the isolator 74. As a result, the load deflection curve before almost complete compression of the isolator 74 exhibits low deflection versus load, but at near or complete compression, the load deflection curve may not generally exhibit the same vibration isolating characteristics. [0045] When the annular portion 80 is of a material that is optimized for the specific application, the most desirable load deflection curve is provided, although an isolator, such as isolator 74, without the annular portion 80 will also result in improved load versus deflection characteristics, as best seen in FIG. 7. The composition as well as the width WA of the annular portion 80 may depend, at least in part, upon the type of application that the isolator 74 is used in. As an example, in an application with a low displacement, with a frequency of the shaft 70 ranging from about five hundred to about eight hundred Hertz (500-800Hz), the annular portion 80 may be an air gap, and the width WA of the annular portion 80 may be at least about two millimeters (2.0 mm). However, in an application with a high displacement, with a frequency of the shaft 70 at about five hundred Hertz (500 Hz), the annular portion 80 may be constructed from a isolating material instead, and the width WA of the annular gap 80 may be less than about two millimeters (2.0 mm).

[0046] An improved load deflection curve will provide for less energy the isolator 74 transfers to the vehicle chassis. Less energy transferred to the vehicle chassis is desirable, because the end result is less vibration experienced by a driver during operating conditions. Additionally, the improved load deflection curve typically reduces shudder by limiting the transfer of vibration to the vehicle chassis.

[0047] While the magnet portions 78, 82 are illustrated as being encased in the isolating material 76, the magnet portions may not be entirely surrounded by the isolating material, but portions 102, 104, 80, 100, 110, 112, and 116 may be partially formed, or formed with apertures therein.

[0048] One method of forming the isolator 74 may involve positioning the segments 118 closer to the outer magnet portion 82 than is illustrated in FIGS. 3 and 5 prior to forming the portions 102, 104, 80, 100, 110, 112, and 116 with the isolating material 74. While the mold used for this forming process would need to overcome the repulsive force F between the segments 118 and the outer magnet portion 82, the resulting isolator 74 would be as illustrated in FIGS. 3 and 5 such that the segments 118 are urged inwardly toward the axis I-I with the portions 110, 112 in radial tension due to the displacement of the segments 118 toward the axis I-I.

[0049] In an alternative illustration, as seen in FIG. 4, the isolator 74 is replaced with an isolator 174. The isolator 174 includes a plurality of segmented inner magnet portions 178 that extend along only a portion of the circumferential path R2. The isolator 174 also includes a plurality segmented outer magnet portions 182 that extend along only a portion of the circumferential path Rl. Both of the inner magnet portions 178 and the outer magnet portions 182 are generally radially spaced. At least one of the inner magnet portions 178 opposes at least one of the outer magnet portions 182. Moreover, at least one of the inner magnet portions 178 may be positioned in about the same radial direction as at least one outer magnet portion 182 with respect to the center axis A-A of the aperture 194. [0050] The present disclosure has been particularly shown and described with reference to the foregoing embodiments, which are merely illustrative of the best modes for carrying out the disclosure. It should be understood by those skilled in the art that various alternatives to the embodiments of the disclosure described herein may be employed in practicing the disclosure without departing from the spirit and scope of the disclosure as defined in the following claims. It is intended that the following claims define the scope of the disclosure and that the method and apparatus within the scope of these claims and their equivalents be covered thereby. This description of the disclosure should be understood to include all novel and non-obvious combinations of elements described herein, and claims may be presented in this or a later application to any novel and non-obvious combination of these elements. Moreover, the foregoing embodiments are illustrative, and no single feature or element is essential to all possible combinations that may be claimed in this or a later application.

Claims

CLAIMSWHAT IS CLAIMED IS:

1. A bearing isolator for a propshaft assembly of a motor vehicle, comprising: an isolating portion generally defining an isolator axis and having an aperture formed therein for receiving a bearing, wherein the aperture, at least partially, defines an inner isolator surface; a generally annular outer magnet portion having a generally cylindrical outer magnet outer portion, a generally cylindrical outer magnet inner portion, an outer first magnetic pole portion, and an outer second magnetic pole portion, wherein the outer first magnetic pole portion is adjacent the outer magnet inner portion, and wherein the outer second magnetic pole portion is adjacent the outer magnet outer portion; and a generally annular inner magnet portion having a generally cylindrical inner magnet outer portion, a generally cylindrical inner magnet inner portion, an inner first magnetic pole portion, and an inner second magnetic pole portion, wherein the inner first magnetic pole portion is adjacent the inner magnet outer portion, and wherein the inner second magnetic pole portion is adjacent the inner magnet inner portion; wherein the outer first magnetic pole portion faces the inner first magnetic pole portion such that the inner magnet exerts a generally radially inward force upon said inner isolator surface.

2. The apparatus of claim 1, wherein the inner isolator surface is generally cylindrical and the isolator is restrained within a restraining portion of the vehicle.

3. The apparatus of claim 1 , wherein at least a portion of the outer magnet portion is encased in the isolating portion.

4. The apparatus of claim 1 , wherein at least a portion of the isolating portion is in tension, wherein the tensile force is exerted at least in part by the inward force.

5. The apparatus of claim 1, wherein the inner magnet portion is selectively positioned radially within the outer magnet portion.

6. The apparatus of claim 1 , wherein the inner magnet portion includes a plurality of inner segments positioned radially within the outer magnet portion, and wherein the inner segments are spaced circumferentially around the inner isolator surface.

7. The apparatus of claim 6, wherein the isolating portion includes a first annular cavity with the outer magnet portion positioned therein, and wherein the isolating portion includes a plurality of annular cavities, with at least a portion of the plurality of annular cavities having at least one inner segment positioned therein.

8. The apparatus of claim 7, wherein the inner segments are spaced circumferentially at generally equal radial distances from the isolator axis.

9. The apparatus of claim 1 , wherein the outer magnet portion includes a plurality of outer segments positioned radially around the inner magnet portion, and wherein the outer segments are spaced circumferentially around the inner isolator surface.

10. The apparatus of claim 9, wherein the outer segments are encased within the isolating portion.

11. The apparatus of claim 1 , wherein the isolating portion is formed of a material selected for vibration isolation properties.

12. A method of isolating a bearing comprising: positioning a generally annular first magnet portion adjacent an isolating material, wherein the first magnet portion is generally defined by an axis; positioning a second magnet portion adjacent the first magnet portion, wherein the second magnet portion includes a plurality of inner segments; interposing the isolating material between the first magnet portion and the inner segments; and urging the plurality of inner segments toward the axis through a magnetically repulsive force.

13. The method of claim 12, further comprising forming the isolating material while overcoming the repulsive force.

14. The method of claim 12, wherein the magnetically repulsive force results from the interaction between the first magnet portion and the inner segments.

15. The method of claim 12, further comprising encasing the first magnet portion with the isolating material.

16. The method of claim 12, further comprising encasing the inner segments with the isolating material.

17. The method of claim 12, wherein the first magnet portion includes a plurality of outer segments.

18. The method of claim 17, further comprising encasing the inner segments with the isolating material.