Lead screw actuator assembly for adjustable position steering wheel

Abstract

A lead screw actuator assembly includes: a lead screw configured to rotate about an axis of rotation; a worm gear coupled to the lead screw to rotate together with the lead screw; a bearing coupled to the lead screw; and a multi-part housing. The multi-part housing includes: a first part at least partially defining a first cylindrical cavity for receiving a rotating spindle of the motor, and the first part at least partially defining a second cylindrical cavity extending along a rotational axis; and a second portion further defining the second cylindrical cavity in which the worm wheel and the bearing are positioned.

Description

Technical Field

[0001] The present disclosure relates generally to adjustable steering wheels, and more particularly to a leadscrew actuator assembly for an adjustable steering wheel. Background Art

[0002] Vehicles (such as cars, trucks, sport utility vehicles, crossovers, minivans, boats, aircraft, all-terrain vehicles, recreational vehicles, or other suitable vehicles) include various steering system solutions (e.g., steer-by-wire steering and driver interface steering). These steering system solutions typically include a steering column assembly for converting steering inputs into outputs that interact with steering linkages to ultimately cause the vehicle wheels to turn. The steering column assembly can be telescopic to allow the user to adjust the distance between themselves and the steering wheel, or rotated about an axis to adjust the height of the steering wheel. However, these assemblies typically include many parts, which increases the cost of the overall system.

[0003] Therefore, there is a continuing need to improve the operating framework of steering wheel assemblies to improve packaging and reduce costs. Summary of the Invention

[0004] According to a first aspect, a lead screw actuator assembly includes: a lead screw configured to rotate about a rotational axis; a worm gear coupled to the lead screw for rotation therewith; a bearing coupled to the lead screw; and a multi-part housing. The multi-part housing includes: a first portion at least partially defining a first cylindrical cavity for accommodating a rotating spindle of a motor, the first portion at least partially defining a second cylindrical cavity extending along the rotational axis; and a second portion further defining a second cylindrical cavity in which the worm gear and the bearing are positioned.

[0005] According to a second aspect, a screw actuator assembly includes: a screw; a worm gear engaged with the screw to rotate with the screw; a multi-part housing including a first part, a second part and an attachment structure, the multi-part housing defining a first cylindrical cavity in which the worm gear is at least partially positioned and a second cylindrical cavity in which the screw is at least partially positioned, each of the first part and the second part at least partially defining the attachment structure, and the attachment structure being constructed to be inserted into the opening to connect the first part and the second part together.

[0006] According to a third aspect, a steering assembly includes: a lower sleeve defining an opening; an upper sleeve capable of moving relative to the lower sleeve; and a lead screw actuator assembly. The lead screw actuator assembly includes: a lead screw configured to rotate about a rotation axis, the lead screw defining a recess and a threaded portion extending along the rotation axis; a worm gear coupled to the lead screw for rotation therewith; a housing defining a cylindrical cavity in which the worm gear is positioned, the housing including an attachment structure configured to be inserted into the opening in the lower sleeve and rotated to attach to the lower sleeve; and a jackscrew nut defining a threaded opening configured to engage the threaded portion of the lead screw such that rotation of the lead screw causes the jackscrew nut to move relative to the housing.

[0007] These and additional features provided by the embodiments described herein will be more fully understood from the following detailed description taken in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] The embodiments illustrated in the drawings are illustrative and exemplary in nature and are not intended to limit the subject matter defined by the claims. The following detailed description of the illustrative embodiments may be understood when read in conjunction with the following drawings, in which like structures are indicated by like reference numerals, and wherein:

[0009] Figure 1 schematically illustrates a vehicle having a steering system according to one or more embodiments shown and described herein;

[0010] Figure 2 Schematically illustrates a device according to one or more embodiments shown and described herein. Figure 1 An exploded perspective view of a lead screw actuator assembly of a steering system;

[0011] Figure 3 Schematically illustrates a device according to one or more embodiments shown and described herein. Figure 2 A partial perspective view of a lead screw actuator assembly;

[0012] Figure 4A and Figure 4B Schematically illustrates a housing mounted to a steering system according to one or more embodiments shown and described herein. Figure 2 a screw actuator assembly;

[0013] Figure 5A Schematically illustrates a method for converting a Figure 2 An actuator assembly is attached to a replacement housing of a steering system jacket; and

[0014] Figure 5BSchematically illustrates a method for converting a Figure 2 Another alternative housing for attaching the actuator assembly to the steering system's jacket. DETAILED DESCRIPTION

[0015] The following discussion is directed to various embodiments of the present disclosure. Although one or more of these embodiments may be described in more detail than other embodiments, the disclosed embodiments should not be interpreted or otherwise used to limit the scope of the present disclosure (including the claims). In addition, it will be understood by those skilled in the art that the following description has broad application, and the discussion of any embodiment is merely meant to illustrate that embodiment and is not intended to imply that the scope of the present disclosure (including the claims) is limited to that embodiment.

[0016] As described, vehicles (such as cars, trucks, sport utility vehicles, crossovers, minivans, boats, aircraft, all-terrain vehicles, RVs, or other suitable vehicles) include various steering systems (e.g., steer-by-wire and driver interface steering). These steering system solutions typically include a steering column assembly for converting steering inputs into outputs that interact with steering linkages to ultimately cause the vehicle wheels to turn. The steering column includes various safety features, such as air bags for reducing impact forces. In addition, many steering column assemblies are collapsible and include one or more energy absorbing features, such as energy absorbing strips, that allow for a specific amount of compression.

[0017] See first Figure 1 , a vehicle 20 is generally shown according to the principles of the present disclosure. Vehicle 20 may include any suitable vehicle, such as a car, truck, sport utility vehicle, minivan, crossover, any other passenger vehicle, any suitable commercial vehicle, or any other suitable vehicle. While vehicle 20 may be a passenger car having wheels and intended for use on roads, the principles of the present disclosure may be applied to other vehicles, such as an airplane, a tractor, a boat, or other suitable vehicles. Vehicle 20 may include a propulsion system 30, such as an ignition system, an electronic system, or a combination thereof.

[0018] In some embodiments, the vehicle 20 may further include a steering system 40. The steering system 40 may be configured as a driver interface steering system, an autonomous driving system, or a system that allows both driver interface and automatic steering. The steering system may include an input device 42 (such as a steering wheel), wherein the driver can mechanically provide steering input by turning the steering wheel. A steering column assembly 44 may include a steering column 45 that extends along an axis from the input device 42 to an output assembly 46. The output assembly 46 may include a pinion shaft assembly, an I-shaft, a cardan joint, a steer-by-wire component, or any other feature conventionally positioned relative to the input device 42.

[0019] The steering column 45 may include at least two axially adjustable portions, for example, a first sleeve 48 and a second sleeve 50 that are axially adjustable relative to each other. The first sleeve 48 may be an upper sleeve and the second sleeve 50 may be a lower sleeve, wherein the first sleeve 48 and the second sleeve 50 are permitted to move axially relative to each other during an impact or other compressive force. The axial movement may include sliding, telescoping, translating, and other axial movements. The steering column assembly 44 may include additional portions that permit axial movement and brackets that provide pitch and tilt movement. The screw actuator assembly disclosed herein may be used for either or both of telescoping and pitch / tilt of the steering wheel. In embodiments that perform both, the vehicle may include two separate screw actuator assemblies. More specifically, the steering column assembly 44 may include a powered actuator (or multiple actuators) wherein the position adjustment is machine driven. The powered actuator may be a screw assembly 52 (in Figure 1 In the form of a screw assembly (schematically shown in FIG), the screw assembly is constructed to axially adjust the position of the second sleeve 50 relative to the first sleeve 48.

[0020] The steering gear assembly 54 can be connected to the output assembly 46 via a steering gear input shaft 56. The steering gear assembly 54 can be configured as a rack and pinion type, a recirculating ball steering gear, or any other type of steering gear associated with automatic steering systems and driver interface steering systems. The steering gear assembly 54 can then be connected to the drive shaft 58 via an output shaft 60. The output shaft 60 can include a pitman arm and a sector gear or other conventional components. The output shaft 60 is operably connected to the steering gear assembly 54 so that rotation of the steering gear input shaft 56 causes responsive movement of the output shaft 60 and causes the drive axle to rotate the wheel 61.

[0021] Now refer to Figure 2, which shows a leadscrew actuator assembly 52 having a motor assembly 100. The motor assembly 100 may include a motor housing 102 for housing a motor 104, wherein the motor 104 includes a rotating spindle 106 having an end piece 108 for transmitting motion from the motor 104 to the leadscrew actuator assembly 52. ​​The leadscrew actuator assembly 52 may generally include a leadscrew 110 configured to rotate about an axis of rotation A, a worm gear 112 coupled to the leadscrew 110 for rotation therewith, a bearing 114 coupled to the leadscrew 110, a two-part housing 116 (also referred to herein as a "multi-part housing"), a shaft bumper 118, a jackscrew nut 120, a travel stop 122, and one or more fasteners 124.

[0022] Although the housing 116 is depicted as having two parts, it is contemplated and possible that the housing 116 has any operable number of parts, such as one, three, or more. For exemplary purposes, the depicted housing 116 includes a first portion 126 and a second portion 128 that is attachable to the first portion 126 to define at least one cavity therein to accommodate various components of the lead screw actuator assembly 52, as will be described in further detail below.

[0023] The first portion 126 of the housing 116 can at least partially define a first cylindrical cavity 130 for accommodating the rotating spindle 106 of the motor 104. The first portion 126 can at least partially define a second cylindrical cavity 132 extending along the rotational axis A of the lead screw 110. The second cylindrical cavity 132 can extend along the rotational axis A to extend obliquely or perpendicularly to the rotational axis B of the rotating spindle 106. The first cylindrical cavity 130 can extend along the rotational axis B of the rotating spindle 106 to allow the rotating spindle 106 to rotate freely within the first cylindrical cavity 130 without contacting the housing 116. The second portion 128 can also define a second cylindrical cavity 132, wherein the worm gear 112 and the bearing 114 are positioned between the first portion 126 and the second portion 128 in the second cylindrical cavity 132. When positioned in the second cylindrical cavity 132, the worm gear 112 and the bearing 114 are surrounded by the housing 116. The first portion 126, the second portion 128, or both may include a dividing wall 133 positioned in the second cylindrical cavity 132 to define or divide the second cylindrical cavity 132 into a worm gear receiving portion 134 and a bearing receiving portion 136. In such an embodiment, the worm gear 112 is positioned in the worm gear receiving portion 134, and the bearing 114 is positioned in the bearing receiving portion 136. The bearing 114 may be positioned in the bearing receiving portion 136 to contact the first portion 126 and / or the second portion 128 in the second cylindrical cavity 132 so that the outer ring of the bearing 114 does not rotate, while the inner ring of the bearing 114 rotates with the lead screw 110. In this configuration, the lead screw actuator assembly 52 may include a single bearing 114 for supporting the lead screw 110, thereby allowing the lead screw 110 to rotate freely while axially retaining the lead screw 110. The bearing 114 may be used to prevent the lead screw 110 from yaw and pitch.

[0024] Each of the first portion 126 and the second portion 128 may include a snap 138 configured to selectively couple to the snap 138 on the other of the first portion 126 and the second portion 128. The snap 138 may be complementary to the other of the first portion 126 and the second portion 128 to allow for selective engagement between the snaps. For example, each of the first portion 126 and the second portion 128 may include the same number of snaps, such as one, two, three, more than three, etc., wherein the snap 138 on the first portion 126 is a male snap 138 and the snap 138 on the second portion 128 is a female snap for engaging with the male snap, or vice versa. The second portion 128 may define an opening 140 opposite the first cylindrical cavity 130 in the first portion 128, wherein the shaft bumper 118 is positioned within the opening 140 in the second portion 126. The opening 140 and the shaft bumper 118 can be positioned so that the shaft bumper 118 is configured to contact the end of the spindle 106 of the motor 104, thereby preventing contact between the second portion 128 of the housing 116 and the motor 104. In other words, the shaft bumper 118 can act as a resistance spring that resists movement of the spindle 106. The shaft bumper 118 can include a handle (not shown) that is inserted into the opening 140 in a press-fit or friction-fit engagement. The handle can prevent the shaft bumper 118 from being removed from the opening 140. The shaft bumper 118 can be formed from a wear-resistant and low-friction material so that contact between the shaft bumper 118 and the spindle 106 of the motor 104 does not reduce the rotational speed of the spindle 106. For example, the shaft bumper 118 can be formed from a hard plastic (methacrylate, polycarbonate, PVC, PETG, ABS, PA (nylon), POM (acetal), etc.), rubber, resin, elastomeric polymer, etc.

[0025] Reference Figure 2 and Figure 4A, the second sleeve 50 can define an opening 180 and one or more cutouts 182 extending radially from the opening 180 in the second sleeve 50 to allow the screw actuator assembly 52 to be attached to the second sleeve 50. The opening 180 and the cutout 182 can be used to couple with the screw actuator assembly 52 in a twist-lock configuration, as will be described in more detail below. Each of the first portion 126 and the second portion 128 of the housing 116 can define one or more fastener openings 142 for receiving one or more fasteners 124, wherein the fasteners 124 can be positioned within the one or more fastener openings 142 in each of the first portion 126 and the second portion 128 to couple the first portion 126 and the second portion 128 together. The fasteners 124 can pass through each of the first portion 126 and the second portion 128 to extend into the opening in the motor housing 102, thereby coupling the housing 116 to the motor housing 102. The housing 116 may also include an attachment structure 144 configured to be inserted into an opening in the lower sheath and rotated to attach to the second sheath 50. The attachment structure 144 may be defined by the first portion 126, the second portion 128, or both. The attachment structure 144 may include a base 146 extending away from the first cylindrical cavity 130 and the second cylindrical cavity 132, and one or more tabs 148 extending from the base 146. The one or more tabs 148 may be sized and positioned to be inserted into the one or more cutouts 182, wherein once inserted into the cutouts 182, the housing 116 may be rotated to position the tabs 148 on the underside of the second sheath 50 at the edge of the opening 180. The housing 116 may be rotated a certain number of degrees to move the tabs 148 away from the cutouts 182, such as, for example, 90 degrees. The tabs 148 can be angled from the ends of the base 146 toward the underside of the housing 116 and the second jacket 50 to contact the underside of the second jacket 50 and form a press-fit coupling between the housing 116 and the second jacket 50. When the attachment structure 144 is inserted into the opening 180 in the second jacket 50, the opening can contact the base 146 on each of the first portion 126 and the second portion 128 as an additional coupling of the two portions 126, 128. In some embodiments, the first portion 126 and the second portion 128 can be coupled together simply by insertion into the opening 180.

[0026] Reference Figure 4A and Figure 4B , the base 146 can extend from the housing 116 to be insertable into the opening 180 in the second sheath 50 so that rotation of the housing 116 causes the tab 148 to engage the underside of the second sheath 50. When the screw actuator assembly 52 is attached to the second sheath 50, the screw 110 and the second sheath 50 extend in the same direction to allow movement of the second sheath 50 along the rotational axis A of the screw 110. Additional attachment structures are contemplated and possible. Specifically, with reference to Figure 5A , a nut 170 or other similar coupling component can be attached to the second housing 50 by welding or the like, wherein an additional fastener 172 can extend through an eyelet 174 attached to the housing 116 to attach to the nut 170, thereby coupling the housing 116 to the second housing 50 ( Figure 4B ). To prevent 126 and 128 from extending away from each other, threaded fasteners 176 may be used in place of openings 180. In some embodiments and with reference to Figure 5B The retaining collar 178 may radially circumscribe the first and second portions 126 , 128 at the attachment structure 144 to couple the first and second portions 126 , 128 together.

[0027] Reference again Figure 2 and Figure 3 , the lead screw 110 may be a conventional lead screw 110, wherein the threaded engagement between the lead screw 110 and the jackscrew nut 120 results in movement of the jackscrew nut 120 along the lead screw 110. For example, Figure 2 As shown, the screw 110 includes: (1) a cam portion 150 having a non-cylindrical cross-sectional shape that is complementary to an opening 152 in the worm gear 112, so that rotation of the worm gear 112 rotates the screw 110; (2) a circular portion 154 that is configured to couple to an opening 156 in the bearing 114; and (3) a threaded portion 158 (in FIG. Figure 2 and Figure 3 1 ), the threaded portion is configured to engage a threaded opening 160 in the jack nut 120 such that rotation of the lead screw 110 moves the jack nut 120 relative to the housing 116. Each of the worm gear 112 and the bearing 114 may include an expanded opening to accommodate a swage insert (not shown) positioned between the lead screw 110 and the corresponding worm gear 112 and bearing 114. The swage insert may increase the retention force between the lead screw 110 and the worm gear 112 and bearing 114, thereby preventing disassembly.

[0028] In the threaded portion 158 or on opposite sides of the threaded portion 158, the screw 110 may define at least one recess, such as a first recess 162 and a second recess 164, wherein the second recess 164 is positioned closer to the housing 116 than the first recess 162. The first recess 162 and the second recess 164 can define the limits of the travel range of the jackscrew nut 120 relative to the housing 116, as described in more detail below with respect to the travel stop 122. Each of the first recess 162 and the second recess 164 can include a radius that gradually decreases from end to end of the respective recess. The recess can at least partially circumferentially surround the screw 110 between the respective ends.

[0029] A travel stop 122 can be coupled to at least one of the lead screw 110 and the jackscrew nut 120, wherein the travel stop 122 includes a head 166 positionable within a recess in the lead screw 110 to limit movement of the jackscrew nut 120 relative to the housing 116. The travel stop 122 can include a clip 168 attached to the jackscrew nut 120, wherein the travel stop 122 biases the head 166 toward the lead screw 110 to be configured to be positioned within the recess.

[0030] The jack nut 120 can define a threaded opening 160 that is configured to engage threads on the lead screw 110 such that rotation of the lead screw 110 moves the jack nut 120 relative to the housing 116. The threaded opening 160 can extend or circumferentially surround the axis of rotation A of the lead screw 110 such that the jack nut 120 can pass over the lead screw 110 toward and away from the housing 116. The jack nut 120 can define a second opening 170 that extends into the threaded opening 160 such that the second opening 170 extends along an axis C that is oblique, transverse, or skewed relative to the axis of rotation A of the lead screw 110. The clip 168 of the travel stop 122 can be attached to the jack nut 120 such that the head 166 of the travel stop 122 extends into the second opening 170 to enable positioning within one of the recessed portions in the lead screw 110. This positioning of the travel stop 122 relative to the jack nut 120 allows the threads on the leadscrew 110 to engage the threaded opening 160 of the jack nut 120 throughout the entire range of motion between the two recesses.

[0031] The jackscrew nut 120 can be attached to a vehicle structure other than the housing 116, so that rotation of the screw 110 moves the second sheath 50 relative to the other vehicle structure, thereby moving the steering wheel toward and away from the driver. This movement of the corresponding structure causes the housing 116 to move relative to the vehicle structure, thereby adjusting the position of the second sheath 50 and the steering wheel relative to the driver.

[0032] It should be noted that the terms "substantially" and "about" may be used herein to represent the inherent degree of uncertainty that may be attributed to any quantitative comparison, value, measurement, or other representation. These terms are also utilized herein to represent the degree by which a quantitative representation may vary from a stated reference without resulting in a change in the basic function of the subject matter at issue.

[0033] While particular embodiments have been shown and described herein, it will be appreciated that various other changes and modifications may be made without departing from the spirit and scope of the claimed subject matter. Furthermore, while various aspects of the claimed subject matter have been described herein, these aspects need not be used in combination. Accordingly, the appended claims are intended to cover all such changes and modifications as come within the scope of the claimed subject matter.

Claims

1. A screw actuator assembly comprising: a lead screw configured to rotate about a rotation axis; a worm gear coupled to the lead screw to rotate together with the lead screw; a bearing coupled to the lead screw; as well as Multi-part housing, comprising: a first portion at least partially defining a first cylindrical cavity for receiving a rotating spindle of a motor, and said first portion partially defining a second cylindrical cavity extending along said rotational axis of said lead screw; as well as The second portion further defines the second cylindrical cavity, wherein the worm gear and the bearing are positioned in the second cylindrical cavity.

2. A screw actuator assembly according to claim 1, wherein at least one of the first part and the second part includes a partition wall, which is positioned in the second cylindrical cavity to define a worm gear receiving portion and a bearing receiving portion, the worm gear is positioned in the worm gear receiving portion, and the bearing is positioned in the bearing receiving portion.

3. The screw actuator assembly of claim 1, wherein each of the first portion and the second portion includes at least one clip configured to selectively couple to the clip on the other of the first portion and the second portion. 4 . The leadscrew actuator assembly of claim 1 , further comprising a shaft bumper positioned within the second portion, the shaft bumper being configured to contact an end of the rotating spindle of the motor.

5. The lead screw actuator assembly of claim 1 , further comprising a jackscrew nut defining a threaded opening configured to engage the lead screw, wherein the lead screw comprises: a cam portion having a non-cylindrical cross-sectional shape complementary to the opening in the worm wheel such that rotation of the worm wheel rotates the leadscrew; a circular portion configured to couple to the opening in the bearing; as well as A threaded portion is configured to engage the threaded opening in the jackscrew nut such that rotation of the leadscrew moves the jackscrew nut relative to the multi-part housing.

6. The screw actuator assembly according to claim 1 further includes one or more fasteners, wherein each of the first part and the second part of the housing defines one or more openings, and the one or more fasteners are positioned within the one or more openings in each of the first part and the second part to connect the first part and the second part together.

7. The screw actuator assembly according to claim 5 further includes a travel stop connected to at least one of the screw and the top screw nut, the travel stop including a head, wherein the screw defines at least one recess, and the head of the travel stop is constructed to be able to be positioned within the at least one recess in the screw to limit the movement of the top screw nut relative to the housing.

8. A screw actuator assembly according to claim 5, wherein the at least one recess includes a first recess and a second recess, the second recess is positioned closer to the housing than the other recess, and the first recess and the second recess define the limits of the travel range of the top screw nut relative to the housing.

9. A screw actuator assembly comprising: Lead screw; a worm gear engaged with the lead screw to rotate together with the lead screw; A multi-part housing comprises a first part, a second part and an attachment structure, wherein the multi-part housing defines a first cylindrical cavity in which the worm gear is at least partially positioned and a second cylindrical cavity in which the screw is at least partially positioned, each of the first part and the second part at least partially defining the attachment structure, and the attachment structure is configured to be inserted into the opening to connect the first part and the second part together.

10. The leadscrew actuator assembly of claim 9, further comprising a boot defining the opening, the boot coupling the first and second portions of the housing together when the attachment structure is inserted into the opening.

11. The leadscrew actuator assembly of claim 10, wherein the attachment structure comprises a base and at least one tab extending from the base.

12. The actuator assembly of claim 11 , wherein the attachment structure comprises a base and at least one tab extending from the base, and the sheath further defines at least one cutout sized and shaped to allow the tab to extend through the cutout when the base is inserted into the opening.

13. The actuator assembly of claim 12, wherein the housing and the sheath are coupled together by insertion of the attachment structure into the opening and rotation of the housing relative to the sheath.

14. The actuator assembly of claim 9, wherein the first and second portions of the housing each at least partially define the second cylindrical cavity.

15. A steering assembly comprising: a lower sheath defining an opening; an upper sheath movable relative to the lower sheath; Screw actuator assembly, comprising: a leadscrew configured to rotate about a rotational axis, the leadscrew defining a recessed portion and a threaded portion extending along the rotational axis; a worm gear coupled to the lead screw to rotate together with the lead screw; a housing defining a cylindrical cavity in which the worm gear is positioned, the housing including an attachment structure configured to be inserted into the opening in the lower jacket and rotated to attach to the lower jacket; and A jackscrew nut defines a threaded opening configured to engage the threaded portion of the leadscrew such that rotation of the leadscrew moves the jackscrew nut relative to the housing.

16. The steering assembly of claim 15, wherein the jackscrew nut is configured to attach to a vehicle structure such that rotation of the leadscrew moves the lower jacket relative to the vehicle structure.

17. The steering assembly of claim 15, wherein the attachment structure comprises one or more tabs, and the lower jacket further defines one or more cutouts extending radially from the opening in the lower jacket, the one or more tabs being sized and positioned to be insertable into the one or more cutouts.

18. The steering assembly of claim 17, wherein the attachment structure further comprises a base from which the one or more tabs extend, the base extending from the housing to be insertable into the opening in the lower jacket such that rotation of the housing engages the tabs with the underside of the lower jacket.

19. The steering assembly of claim 15, wherein when the leadscrew actuator assembly is attached to the lower housing, the leadscrew and the lower housing extend in the same direction to allow movement of the lower housing along the axis of rotation of the leadscrew.

20. The steering assembly of claim 15, wherein the housing is a multi-part structure comprising: a first portion at least partially defining the cylindrical cavity; as well as A second portion further defines the cylindrical cavity, wherein each of the first portion and the second portion defines the attachment structure.

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