Multi-axis damper for steering rack bar

Abstract

A multi-layer radial damper is configured to attenuate forces applied in a radial direction between an automotive rack bar and a bushing sleeve that protects the rack bar. The radial damper may include a layer made of a polymeric material. The radial damper may also attenuate forces applied in the axial direction between the tie rod and the bushing sleeve.

Description

Technical Field

[0001] The present disclosure relates to damper components implemented in automotive steering systems. Background Art

[0002] The steering rack in a car is subject to a variety of forces when the car is in motion. These forces can be felt in both axial and radial directions. Axial forces are experienced when the steering rack is subjected to forces in the direction of the axis of the steering rack. Axial forces can negatively affect vehicle performance by causing displacement of the steering rack, misalignment of the steering rack or wheels, or wear on components of the steering rack. Radial forces are experienced when the wheels of the vehicle are subjected to forces in a direction perpendicular to the axis of the steering rack. Radial forces can negatively affect vehicle performance by causing misalignment of the wheels and the steering rack, or wear on components of the steering rack. Since the forces are applied in three dimensions, external forces can include axial and radial components.

[0003] It is desirable to protect steering rack components from the negative effects of external forces in both axial and radial directions. In existing systems, axial dampers may be applied to reduce the negative effects of axial forces. However, it would be desirable to develop a damper that can be applied to conventional steering systems that additionally provides damping protection against radial forces. Summary of the invention

[0004] One aspect of the present disclosure relates to a radial damper configured to be positioned around a rack rod within a rack support bushing sleeve of an automotive steering rack in an automotive vehicle. The radial damper includes a first layer and a second layer. The first layer has a first inner surface, the first inner surface being disposed at a first radial proximity to the rack rod, and a first outer surface opposite the first inner surface. The second layer has a second inner surface and a second outer surface, the second inner surface being disposed at a second outward radial proximity greater than the first radial proximity to the rack rod and adjacent to the first outer surface. When in position during automotive motion, the radial damper attenuates radial forces applied by the rack support bushing sleeve to the rack rod. The first layer includes a first thickness in a radial direction relative to the rack rod, and the second layer includes a second thickness in a radial direction relative to the rack rod. The second layer is more resilient to radial forces than the first material. In some embodiments, the radial damper also includes a third layer having a third inner surface and a third outer surface, the third inner surface being disposed at a third outward radial proximity greater than the second radial proximity to the rack rod and adjacent to the second outer surface. The third layer includes a third thickness in a radial direction relative to the rack bar, and the third outer surface is adjacent to a surface of the rack support bushing sleeve.

[0005] Another aspect of the present disclosure relates to a radial damper configured to be positioned around a rack rod within a bushing sleeve of an automotive steering rack in an automotive vehicle, the radial damper comprising a first layer having a first rack surface, a first sleeve surface disposed parallel to the first rack surface, and a first interface surface, wherein when the radial damper is positioned around the rack rod, the first rack surface is closer to the rack rod than the first sleeve surface, and the first sleeve surface is closer to the bushing sleeve than the first rack surface. The radial damper also comprises a second layer having a second rack surface, a second sleeve surface disposed parallel to the second rack surface, and a second interface surface, wherein when the radial damper is positioned around the rack rod, the second rack surface is closer to the rack rod than the second sleeve surface, and the second sleeve surface is closer to the bushing sleeve than the second rack surface. The radial damper also comprises a third layer disposed between the first material and the second material, the third material extending between the first interface surface and the second interface surface. The radial damper damps radial forces exerted by the bushing sleeve on the rack bar during vehicle motion, wherein the first rack surface has a larger axial dimension than the first sleeve surface, and wherein the second sleeve surface has a larger axial dimension than the second rack surface.

[0006] Another aspect of the present disclosure relates to a radial damper configured to be positioned around a rack rod within a bushing sleeve of an automotive steering rack in an automobile. The radial damper includes a first layer having a first rack surface and a first interface surface. The first sleeve surface is disposed parallel to the first axial surface. When the radial damper is positioned around the rack rod, the first rack surface is closer to the rack rod than the first sleeve surface, and the first sleeve surface is closer to the bushing sleeve than the first rack surface. The radial damper also includes a second layer disposed between the first layer and the bushing sleeve. The radial damper attenuates radial forces applied by the bushing sleeve to the rack rod during movement of the automobile. The second layer extends from the first interface surface, wherein the first rack surface has an axial dimension larger than the first sleeve surface, and wherein the second layer has greater resilience to radial forces than the first layer.

[0007] Another aspect of the present disclosure includes a radial damper configured to be positioned about a rack rod within a bushing sleeve of an automotive steering rack in an automotive vehicle. The radial damper includes a first layer having a first portion adjacent to the rack rod and a second portion adjacent to the bushing sleeve, and a second layer disposed between the first portion and the bushing sleeve. The first portion and the second portion form an angle.

[0008] The above-mentioned aspects and other aspects of the present disclosure will be explained in more detail below with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Figure 1 is a cross-sectional view of a portion of a steering rack with a radial damper in place.

[0010] Figure 2 yes Figure 1 View of the radial damper used in.

[0011] Figure 3 yes Figure 1 Close-up cross-section of the radial damper in place.

[0012] Figure 4 is a cross-sectional view of a portion of a steering rack with a radial damper.

[0013] Figure 5 yes Figure 4 Close-up cross-section of the radial damper in place.

[0014] Figure 6 is a cross-sectional view of a portion of a steering rack with a radial damper in place.

[0015] Figure 7 yes Figure 6 Close-up cross-section of the radial damper in place.

[0016] Figure 8 is a view of an alternative embodiment of a radial damper. DETAILED DESCRIPTION

[0017] The illustrated embodiments are disclosed with reference to the accompanying drawings. However, it should be understood that the disclosed embodiments are intended only as examples, which may be embodied in various alternative forms. The drawings are not necessarily drawn to scale, and certain features may be exaggerated or minimized to show details of particular components. The specific structural and functional details disclosed should not be interpreted as limiting, but rather as a representative basis for teaching those skilled in the art how to practice the disclosed concepts.

[0018] Figure 1 A cross-sectional view of a steering rack 100 is shown, the steering rack 100 including a rack bar 101 and a bushing sleeve 103. The bushing sleeve 103 protects the rack bar 101 from the effects of inclement weather and also provides direction and limitation to the movement of the rack bar 101, thereby providing reliable movement for steering a vehicle including the steering rack 100. A steering column (not shown) is operable to move the steering rack 101 in an axial direction 104 of the steering rack 101. The rack bar 101 is fixed to a tie rod 105, connecting the wheels of the vehicle to the rack bar 101 for the purpose of controlling steering. In the illustrated embodiment, the tie rod 105 includes a tie rod socket 107 coupled to the rack bar 101 and a tie rod ball 109 coupled to a wheel (not shown). The tie rod ball 109 is coupled within the tie rod socket 107 to secure the wheel to the rack bar 101.

[0019] Too much displacement of the rack bar 101 in the axial direction 104 is undesirable because it may force the wheel or tie rod 105 to physically interact with other elements of the vehicle in an undesirable manner. To prevent the rack bar 101 from overextending in the axial direction 104, the bushing sleeve 103 additionally includes one or more retainers 111.

[0020] Since the rack bar 101 has a longitudinal shape, any force applied to the rack bar in a direction perpendicular to the axial direction 104 is necessarily a radial force. When the components of the steering rack 100 interact with each other under the action of forces, the application of radial forces to the rack bar 101 may cause deformation or wear of the components of the steering rack 100. For this reason, a radial damper 113 is provided in the steering rack. The radial damper 113 is configured to attenuate the radial forces applied to the rack bar 101 and help minimize the physical interaction between the bushing sleeve 103 and other components of the steering rack 100. In the present disclosure, the radial damper 113 also provides axial damping to prevent direct interaction between the tie rod 105 and any portion of the bushing sleeve 103 (including the retainer 111).

[0021] The placement of the radial damper 113 is critical to optimizing the damping effect. Figure 2 An illustration of the radial damper 113 is provided to illustrate the configuration of one embodiment of the radial damper 113. The radial damper 113 comprises an annular shape having an inner diameter 200. The inner diameter 200 can be of any size, but it must be large enough to accommodate the diameter of the rack bar 101 (see Figure 1 ) without interfering with the operation of the steering rack 100. In the illustrated embodiment, the radial damper 113 includes a multi-layer configuration including a first layer 201, a second layer 203, and a third layer 205.

[0022] The first layer 201 includes a first material and has a first inner surface 207 and a first outer surface 209, which define the boundaries of the first layer 201. It is worth noting that the first inner surface 207 is configured to contact the rack bar 101 when the rack bar 101 is subjected to a radial force (see Figure 1 ). Due to this interaction, the first layer 201 is advantageously composed of a material that is not hard enough to cause damage to the rack bar 101 through wear. In the illustrated embodiment, the first material comprises a metal that is softer than the metal that constitutes the rack bar 101. Other embodiments may include other material combinations without departing from the teachings disclosed herein.

[0023] The second layer 203 includes a second material and has a second inner surface 211 and a second outer surface 213, which define the boundaries of the second layer 203. The second inner surface 207 is configured to contact the first outer surface 209 of the first layer 201. In the illustrated embodiment, the two layers are coupled using a mechanical or chemical bonding technique so that this contact between the second inner surface 207 and the first outer surface 209 becomes a continuous static contact. Other embodiments may include other forms of contact between the two layers without departing from the teachings disclosed herein. This coupling advantageously optimizes the transfer of radial forces experienced by the contact between the first layer 201 and the rack bar 101 to the second layer 203. Other embodiments may include other forms of contact between the two layers without departing from the teachings disclosed herein. In the illustrated embodiment, the second layer 203 is composed of a second material that is different from the first material of the first layer 201. In Figure 2 In the depiction of , the second material comprises a polymer, such as an elastomer. The polymer material can be selected based on the desired properties, such as elasticity, hardness, and resilience. Elasticity is particularly advantageous because it provides a damping effect on the radial forces transmitted from the rack bar 101 to the radial damper 113, thereby reducing the forces exchanged between the components and reducing the wear experienced during this interaction.

[0024] The third layer 205 includes a third material and has a third inner surface 215 and a third outer surface 217, which define the boundaries of the third layer 205. The third layer 205 is configured to contact the second outer surface 213 of the second layer 203. In the illustrated embodiment, the two layers are connected by using a mechanical or chemical bonding technique so that this contact between the third inner surface 215 and the second outer surface 213 becomes a continuous static contact. Other embodiments may include other forms of contact between the two layers without departing from the teachings disclosed herein. In the illustrated embodiment, the connection advantageously reduces wear on the second outer surface 213 and the third inner surface 215, extending the service life of the two layers. The third outer surface 217 is configured to contact the bushing sleeve 103 (see FIG. 2 ) when the rack bar 101 is subjected to a sufficiently large radial force. Figure 1 ) contact. Due to this interaction, the third layer 205 is advantageously composed of a material that is not hard enough to cause damage to the bushing sleeve 103 through wear. In the illustrated embodiment, the third material comprises a metal that is softer than the metal that constitutes the bushing sleeve 103. In the illustrated embodiment, the first material of the first layer 201 and the third material of the third layer 205 can be the same. Other embodiments may include other arrangements without departing from the teachings disclosed herein.

[0025] In the illustrated embodiment, each of the first layer 201, the second layer 203, and the third layer 205 includes a thickness of the material from which it is made. With respect to these teachings, "thickness" is defined as the extension of the material in the radial direction relative to the annular shape of the radial damper 113. In the illustrated embodiment, each layer has its own unique thickness. However, other configurations may include other arrangements without departing from the teachings disclosed herein. In some such embodiments, two or more layers may have the same thickness without departing from the teachings disclosed herein. As an example and not limitation, in some embodiments, the first layer 201 and the third layer 205 may have the same thickness as each other. This may advantageously allow the radial damper 113 to be manufactured using joint resource materials.

[0026] In the illustrated embodiment, the thickness of the first layer 201 and the third layer 205 are different. In such an embodiment, this difference can advantageously optimize the service life of the components of the radial damper 113 because the frequency at which the first inner surface 207 is expected to interact with the rack bar 101 is much higher than the frequency at which the third outer surface 217 is expected to interact with the bushing sleeve 103. Therefore, the thickness difference can optimize the service life of the radial damper 113 while also maximizing the thickness of the second layer 203, which advantageously maximizes the damping effect. In the illustrated embodiment, the polymer material of the second layer 203 has greater resilience than the metal material used in the first layer 201 or the third layer 205, but other embodiments may include other material properties without departing from the teachings disclosed herein.

[0027] Figure 3 A close-up cross-sectional view of the radial damper 113 in place when positioned about the rack bar 101 is provided. It is noteworthy that whenever a radial force in a radial direction 304 is applied to the rack bar 101 by a wheel (not shown), the rack bar 101 will first interact with the radial damper 113 before interacting with any portion of the bushing sleeve 103. Although this cross-section is a two-dimensional representation, any radial force in any radial direction will create an interaction between the rack bar 101 and the radial damper 113 prior to any interaction with the bushing sleeve 103. It is noteworthy that this includes the portion of the bushing sleeve 103 that constitutes the retainer 111.

[0028] In some embodiments, the axial alignment of one or more layers may exhibit a particular arrangement. For purposes of this disclosure, a cross-sectional arrangement of layers may be considered axially aligned if the cross-sectional center points of each layer are aligned within a tolerance of 5% of the total axial dimension of each respective layer relative to the axial direction 104. Two arranged layers may not have the same size relative to their respective axial dimensions. In such an arrangement, the layers may be considered axially aligned if the cross-sectional center points are aligned within a tolerance of 5% of the total axial dimension of the layer having the smaller size relative to the axial dimension along the axial direction 104. If the center points of any two layers are not aligned within a 5% tolerance, the layers are considered axially offset.

[0029] In the illustrated embodiment, the radial damper 113 includes a first layer 201, a second layer 203, and a third layer 205, all of which are axially aligned. Other embodiments may include one or more layers that are axially offset from the other layers without departing from the teachings disclosed herein. By way of example and not limitation, an axially offset embodiment may include a second layer 203 that is disposed further away from the retainer 111 than the first layer 201. In such an embodiment, the third layer 205 may be disposed even further away from the retainer 111. Thus, in such an example embodiment, each of the first layer 201, the second layer 203, and the third layer 205 is axially offset from the other layers. Other embodiments may include other arrangements of axially aligned layers without departing from the teachings disclosed herein.

[0030] Other configurations of radial dampers may be used. Figure 4 A cross-sectional view of the same steering rack 100 is provided having an alternative radial damper configuration in the form of a radial damper 413. The radial damper 413 retains the same radial damper configuration as the radial damper 113 (see Figure 2 ) have the same generally annular shape but include different arrangements of cross-sectional components.

[0031] Figure 5A close-up cross-sectional view of the radial damper 413 in place when positioned about the rack bar 101 is provided. The radial damper 413 includes a first layer 501 having a first rack surface 503, a first interface surface 505, and a first sleeve surface 507. In the first layer 501, the first rack surface 503 is disposed closest to the rack bar 101, while the first sleeve surface 507 is disposed opposite the first rack surface 503, which itself is closest to the bushing sleeve 103. The first interface surface 505 extends between the first rack surface 501 and the first sleeve surface 507. In the illustrated embodiment, the first rack surface 501 includes a width that is greater than the width of the first sleeve surface 507, and the first interface surface 505 includes a bracket configuration such that the cross-section of the first layer 501 is "L" shaped. In the illustrated embodiment, the "L" shape includes a right angle, but other embodiments may include other angles without departing from the teachings disclosed herein. Other configurations may include other arrangements and dimensions without departing from the teachings disclosed herein.

[0032] The radial damper 413 further includes a second layer 509 having a second rack surface 511, a second interface surface 513, and a second sleeve surface 515. In the second layer 509, the second rack surface 511 is arranged closest to the rack bar 101, while the second sleeve surface 515 is arranged opposite to the second rack surface 511, and the second sleeve surface 515 itself is closest to the bushing sleeve 103.

[0033] The second interface surface 513 extends between the second rack surface 511 and the second sleeve surface 515. In the illustrated embodiment, the second rack surface 511 includes a width that is less than the width of the second sleeve surface 515, and the second interface surface 513 includes a bracket configuration so that the cross-section of the second layer 515 is "L" shaped. In the illustrated embodiment, the "L" shape includes a right angle, but other embodiments may include other angles without departing from the teachings disclosed herein. In the illustrated embodiment, the orientation of the "L" shape in the cross-section of the second layer 509 is reversed in the vertical direction compared to the first layer 501. Other configurations may include other arrangements and dimensions without departing from the teachings disclosed herein.

[0034] The radial damper 413 also includes a third layer 517 that spans between the first interface surface 505 and the second interface surface 513. In the illustrated embodiment, the third layer 517 includes a third rack surface 519 disposed near the rack bar 101 and a third sleeve surface 521 disposed near the bushing sleeve 103. In the illustrated embodiment, the third layer 517 spans between the first interface surface 505 and the second interface surface 513, spanning the entire length of each surface, but other embodiments may include other configurations without departing from the teachings disclosed herein. In such an embodiment, the third rack surface 519 may be at a greater distance from the steering rack 101 than either the first rack surface 503 or the second rack surface 511 without departing from the teachings disclosed herein. In such an embodiment, the third sleeve surface 521 may be at a greater distance from the bushing sleeve 103 than either the first sleeve surface 507 or the second sleeve surface 515 without departing from the teachings disclosed herein.

[0035] The first layer 501 may include a metal. The second layer 509 may include a metal, and in the illustrated embodiment, the metal may include the same metal as the first layer 501, but other embodiments may have other configurations without departing from the teachings disclosed herein. The third layer 517 may include a polymer, particularly an elastomer. In the illustrated embodiment, the material used in the first layer 501, the second layer 509, or the third layer 517 may not be hard enough to damage the rack bar 101 or the bushing sleeve 103 due to wear when in contact due to radial forces exerted on the rack bar 101. Advantageously, the third layer 517 provides a damping effect on the transmission of radial and axial forces experienced between the rack bar 101 and the bushing sleeve 103. The material of each of the first layer 501, the second layer 509, and the third layer 517 should be selected to be able to withstand the expected forces without degrading or damaging the radial damper 413 under normal operating conditions. In the illustrated embodiment, the polymer material of the third layer 517 is more resilient than the metallic material used in the first layer 501 or the second layer 203, but other embodiments may include other material properties without departing from the teachings disclosed herein.

[0036] Figure 6 A cross-sectional view of the same steering rack 100 is provided having an alternative radial damper configuration in the form of a radial damper 613. The radial damper 613 retains the same radial damper configuration as the radial damper 113 (see Figure 2 ) have the same generally annular shape but include different arrangements of cross-sectional components.

[0037] Figure 7A close-up cross-sectional view of the radial damper 613 in place when positioned about the rack bar 101 is provided. The radial damper 613 includes a first layer 701 having a first rack surface 703, a first interface surface 705, and a first sleeve surface 707. In the first layer 701, the first rack surface 703 is disposed closest to the rack bar 101, while the first sleeve surface 707 is disposed opposite the first rack surface 703, which itself is closest to the bushing sleeve 103. The first interface surface 705 extends between the first rack surface 701 and the first sleeve surface 707. In the illustrated embodiment, the first rack surface 701 includes a width that is greater than the width of the first sleeve surface 707, and the first interface surface 705 includes a bracket configuration such that the cross-section of the first layer 701 is "L"-shaped. In the illustrated embodiment, the "L" shape of the cross-section includes a right angle, but other embodiments may include other angles without departing from the teachings disclosed herein. Other configurations may include other arrangements and dimensions without departing from the teachings disclosed herein.

[0038] The radial damper 613 additionally includes a second layer 709 extending from the first interface surface 705. In the illustrated embodiment, the second layer 709 includes a second sleeve surface 711 that is disposed closer to the bushing sleeve 103 than the first interface surface 705. In the illustrated embodiment, the second layer 709 is configured to directly engage the bushing sleeve 103 when the rack bar 101 is subjected to radial forces under normal operating conditions. Therefore, the second layer 709 is composed of a material that will not damage the bushing sleeve 103 through wear or other interactions during movement of the vehicle under normal operating conditions.

[0039] The first layer 701 may include a metal. The second layer 709 may include a polymer, particularly an elastomer. In the illustrated embodiment, the material used in either the first layer 701 or the second layer 709 may not be hard enough to damage the rack bar 101 or the bushing sleeve 103 due to wear when in contact due to radial forces exerted on the rack bar 101. Advantageously, the second layer 709 provides a damping effect on the transmission of radial and axial forces experienced between the rack bar 101 and the bushing sleeve 103. The material of each of the first layer 701 and the second layer 709 should be selected to be able to withstand the expected forces without degrading or damaging the radial damper 413 under normal operating conditions. In the illustrated embodiment, the polymer material of the second layer 709 has a greater resilience than the metal material used in the first layer 201, but other embodiments may include other material properties without departing from the teachings disclosed herein.

[0040] In the previously illustrated embodiments, each layer of the respective radial damper comprises a set of layers that are uniformly sized and arranged throughout the annular structure of the radial damper. However, alternative arrangements may be used without departing from the teachings disclosed herein. Figure 8 A radial damper 813 is included that depicts one such configuration, which is arranged and configured similarly to radial damper 113 (see Figure 2 ) is equivalent. In the illustrated embodiment, the radial damper 813 includes the same dimensions and the same configuration as the first layer 201 and the third layer 205 shown in the radial damper 113. However, the radial damper 813 includes a second layer 815 that is different from the second layer 203 of the radial damper 113. The second layer 815 includes the same external dimensions and cross-sectional characteristics as the second layer 203, but also has many voids 815 within the material. The voids 815 can advantageously provide space for the polymer body within the second layer 815 to undergo deformation when attenuating radial or axial forces, thereby improving the damping effect exhibited by the radial damper 813. In addition, the voids can allow the layers to be manufactured efficiently, such as using a specialized extrusion process. In an additional advantage, large-scale manufacturing of the radial damper 813 can be more cost-effective because the voids require less batch material each time the second layer 813 is repeatedly manufactured.

[0041] The vacancies 815 may exhibit any n-order radial symmetry within the second layer 813. In the illustrated embodiment, the vacancies exhibit 8-order radial symmetry, but other embodiments may include other configurations without departing from the teachings disclosed herein. In the illustrated embodiment, each vacancy comprises a circular vacancy, but other embodiments may include other shapes or different shapes in the same embodiment without departing from the teachings disclosed herein. In the illustrated embodiment, each of the first layer 201 and the third layer 205 comprises a continuous and regular arrangement of materials, but other embodiments may include other configurations without departing from the teachings disclosed herein.

[0042] Although exemplary embodiments are described above, these embodiments are not intended to describe all possible forms of the disclosed apparatus and methods. Instead, the words used in the specification are descriptive rather than restrictive, and it should be understood that various changes may be made without departing from the spirit and scope of the disclosure claimed. The features of various implemented embodiments may be combined to form further embodiments of the disclosed concepts.

Claims

1. A radial damper configured to be positioned around a rack rod within a rack support bushing sleeve of an automotive steering rack in an automotive vehicle, the radial damper comprising: a first layer having a first inner surface disposed at a first radial proximity to the rack bar and a first outer surface opposite the first inner surface; as well as a second layer having a second inner surface and a second outer surface, the second inner surface being disposed at a second outward radial approach to the rack bar greater than the first radial approach and adjacent to the first outer surface, wherein the radial damper attenuates radial forces applied by the rack support bushing sleeve to the rack rod during vehicle movement, wherein the first layer includes a first thickness in a radial direction relative to the rack rod and the second layer includes a second thickness in a radial direction relative to the rack rod, and wherein the second layer has greater resilience to radial forces than the first material.

2. The radial damper according to claim 1 further includes a third layer having a third inner surface and a third outer surface, the third inner surface is arranged at a third outward radial approach to the rack rod greater than the second radial approach and adjacent to the second outer surface, the third layer includes a third thickness in a radial direction relative to the rack rod, and wherein the third outer surface is adjacent to the surface of the rack support bushing sleeve.

3. The radial damper of claim 2, wherein the first layer is metal, the second layer is polymer, and the third layer is metal.

4. The radial damper of claim 3, wherein the first layer and the third layer are composed of the same metal. The radial damper of claim 2 , wherein the first thickness is a uniform thickness. The radial damper of claim 2 , wherein the second thickness is a uniform thickness.

7. The radial damper of claim 1, wherein the first layer comprises a metal and the second layer comprises a polymer.

8. The radial damper of claim 7, wherein the second layer comprises an elastomer.

9. The radial damper of claim 2, wherein the second layer has at least one void between the second inner surface and the second outer surface.

10. The radial damper of claim 2, wherein the first layer, the second layer, and the third layer are axially aligned.

11. The radial damper of claim 2, wherein the first layer is axially offset from the second layer or the third layer.

12. The radial damper of claim 11, wherein the first layer is axially offset from the second layer and the third layer.

13. The radial damper of claim 1, wherein the first layer is axially offset from the second layer.

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