FIELD

[0001] The described examples relate generally to a belt tensioner, and more particularly to belt-driven starter-generator (BSG) systems and techniques that facilitate connecting a BSG tensioner device to a Motor Generator Unit (MGU).

BACKGROUND

[0002] Belt tensioners are used to apply a load to a belt. The belt load prevents the belt from slipping on one or more entrained pulleys during operation. Typically, the belt is used in an engine application for driving various accessories associated with the engine. For example, an air conditioning compressor and an alternator are two possible accessories that can be driven by a belt drive system.

[0003] A belt tensioner may include a pulley mounted to an arm. A spring is connected between the arm and a base. The spring may also engage a damping mechanism. The damping mechanism comprises a frictional surface engaged with the arm or the base. The damping mechanism dissipates vibration energy from the belt system and reduces oscillatory movement of the arm that is caused by rotational vibration of the engine crankshaft during operation of the belt drive.

[0004] Belt tensioners have been used for a very long time in the belt-pulley power transmission industry. For example, in the automotive industry, tensioners have been used to adjust and optimize the belt tension for target performance of serpentine belt drives. Conventional mechanical tensioners typically control belt tension at a belt span. The belt span may typically be a slack-side of the belt, for example, due to the accessory loads being in a common direction at the slack-side, as driven by the engines. For BSG systems, special tensioners are designed to control belt tension according to MGU operations. For example, in a generating mode, the tensioner may operate to control tension of a slack-side span, which is located before MGU pulley in belt moving direction. As another example, in a motoring mode, when the MGU pulley becomes a driver, the tensioner may operate to control tension of another slack-side span, which is located after the MGU pulley in belt moving direction.

[0005] The housings or bases of BSG tensioners are typically bolted or otherwise fixed relative to a Motor Generator Unit housing, engine block or engine associated structure. Such BSG tensioner mounting increases the footprint and weight of the tensioner and the mounting counterpart, and reduces the adaptability of the tensioner to certain high-performance applications. Further drawbacks of conventional systems include the belt alignment with the MGU pulley. For example, if the tensioner arm pulley before the MGU pulley in the belt moving direction does not maintain the required bearing seat angle or height, the belt may make noise, be damaged in operation, or even fall off the pulley. Typical tensioner device mountings may result in belt misalignment from manufacturing tolerance of tensioner base and mounting counterpart, and wearing of supporting elements such as plastic bearing bushings between tensioner’s base and arm. As such, the need continues for systems and techniques to optimize the performance of tensioner devices, including those that reduce weight and complexity without sacrificing performance including alignment.

SUMMARY

[0006] Examples of the present invention are directed to tensioner devices, coupling features that facilitate direct coupling of the tensioner device to Motor Generator Units, and assemblies and methods of manufacture thereof.

[0007] In one example, a tensioner device for installation on a Motor Generator Unit (MGU) is disclosed. The tensioner device includes a first pulley mountable on a rotatable shaft of the MGU for turning with a rotation of the rotatable shaft. The first pulley is adapted to engage and drive, or be driven by, a belt. The tensioner device further includes a coupling feature connected to one or both of the first pulley or the rotatable shaft. The tensioner device further includes a first rotary arm connected to the coupling feature. The coupling feature is adapted to allow for movement of the first rotary arm relative to the first pulley. The tensioner device further includes a second rotary arm arranged for movement relative to the first rotary arm. The tensioner device further includes a second pulley journalled to the second rotary arm and adapted to engage the belt using a biasing element. The tensioner device further includes a third pulley journalled within the tensioner device for engagement of the belt, the second and third pulleys being disposed about the first pulley for establishing a belt path along the first, second, and third pulleys.

[0008] In another example, an assembly is disclosed. The assembly includes a Motor Generator Unit (MGU) with a rotatable shaft. The assembly further includes a tensioner device mounted directly on the rotatable shaft and configured to impart tension in a belt. The tensioner device includes a first pulley for turning with a rotation of the rotatable shaft, the first pulley being adapted to engage and drive, or be driven by, the belt. The tensioner device further includes a coupling feature moveable with the first pulley and allowing for movement of a rotary arm of the tensioning device relative to the rotatable shaft.

BRIEF DESCRIPTION OF THE DRAWINGS

[0009] The disclosure will be readily understood by the following detailed description in conjunction with the accompanying drawings, wherein like reference numerals designate like structural elements, and in which:

[0010] FIG. 1 depicts an example assembly including a Motor Generator Unit and tensioner device;

[0011] FIG. 2 depicts an exploded view of the assembly of FIG. 1;

[0012] FIG. 3 depicts an exploded view of the tensioner device of FIG. 1;

[0013] FIG. 4 depicts a front view of the assembly of FIG. 1;

[0014] FIG. 5 depicts a cross-sectional view of the assembly of FIG. 1, taken along line 5-5 of FIG. 4;

[0015] FIG. 6 depicts a detail view of an example of the tensioner device of FIG. 5;

[0016] FIG. 7 depicts a detail view of another example of the tensioner device of FIG. 5;

[0017] FIG. 8 depicts a detail view of another example of the tensioner device of FIG. 5; [0018] FIG. 9 depicts a detail view of another example of the tensioner device of FIG. 5, including a damping feature;

[0019] FIG. 10 depicts a front view of another example of an assembly including a Motor Generator Unit and a tensioner device;

[0020] FIG. 11 depicts a cross-sectional view of the assembly of FIG. 10, taken along line I ll i of FIG. 10;

[0021] FIG. 12 depicts a front view of another example of an assembly including a Motor Generator Unit and a tensioner device;

[0022] FIG. 13 depicts a cross-sectional view of the assembly of FIG. 12, taken along line 13- 13 of FIG. 12;

[0023] FIG. 14A depicts a detail view of another example of the tensioner device of FIG. 13; and

[0024] FIG. 14B depicts a detail view of another example of the tensioner device of FIG. 13.

DETAILED DESCRIPTION

[0025] The description that follows includes sample systems, methods, and apparatuses that embody various elements of the present disclosure. However, it should be understood that the described disclosure may be practiced in a variety of forms in addition to those described herein.

[0026] Before referring to the Figures, a brief explanation is provided. The present disclosure describes tensioner devices, and assemblies and methods of manufacture thereof. A sample tensioner device of the present disclosure may include a pulley that is journalled to an arm. The pulley may be adapted to engage a belt, such as a serpentine belt of an automotive or other engine system. The pulley may apply a load to the belt in order to tension the belt and optimize belt performance. For example, the tensioner devices of the present disclosure may include a biasing element that is adapted to bias the arm (and journalled pulley) toward a run or span of the belt, thereby tensioning the belt to a desired value. Conventional mechanical tensioners often arrange the arm, biasing element, and other components within, or are otherwise associated with, a tensioner device housing. Such tensioner device housings of the conventional system are then fixed directly to a Motor Generator Unit (MGU) or other engine component for installation, with the housing or overall footprint often decreasing the adaptability of the tensioner device.

[0027] The tensioner device of the present disclosure may mitigate such hindrances by implementing one or more coupling features that allows for attachment of the tensioner device to the MGU without a housing. The coupling features may allow the tensioner device to be directly coupled, for example, to a rotatable shaft of the MGU without bolting or otherwise fixing a housing of the tensioner device to the MGU. By removing the housing, the tensioner device of the present disclosure may be lighter and more compact than existing designs without sacrificing performance of the system. Assembly may also be improved, where the tensioner device is directly coupled to the rotatable shaft, thereby reducing or eliminating additional assembly steps associated with bolting or other attachment techniques required to install conventional tensioner devices.

[0028] To facilitate the foregoing, the tensioner device may include a first or “drive” pulley that may be mountable on a rotatable shaft for turning with a rotation of the rotatable shaft. The first pulley may be adapted to engage and drive, or be driven by, a belt. The tensioner device may further include a first rotary arm and a second rotary arm that are moveable relative to one another. A second or “idler” pulley may be journalled to the second rotary arm to engage and tension the belt. Tension may be established using a biasing element that is operatively connected to the first and second rotary arms. A third or “idler” pulley may be journalled to the first rotary arm allowing the first, second, and third pulleys to establish a belt path relative to the MGU.

[0029] A coupling feature of the tensioner device may facilitate direct coupling of the tensioner device to the MGU without relying on excess housing components. Broadly, the coupling feature may be used to connect the first rotary arm to the first pulley and establish movement of the first rotary arm relative to the first pulley. In this regard, the first pulley may turn with the rotation of the rotatable shaft, and the first rotary arm may float relative to, or otherwise move independent of, the movement of the rotatable shaft. Other components of the tensioner device may be connected, directly or indirectly, to the first rotary arm, for example, the second rotary arm, the biasing element, the second pulley, the third pulley, and so on. Accordingly, the coupling features of the present disclosure allows these and other features to be supported in the tensioner device via the rotatable shaft of the MGU, rather than be included in, or supported by, a housing structure, independently fixed to the MGU housing or to some other fixed frame on a vehicle.

[0030] The coupling feature, in one example, may include a bearing assembly. The bearing assembly may include a first race and a second race that is moveable relative to the first race. The first and second races may therefore cooperate to establish movement of the first rotary arm relative to the first pulley. In one illustration, the first race is connected to the first pulley for turning with the rotation of the rotatable shaft, and the second race is connected to the first rotary arm allowing the first rotary arm to move independent of the rotation of the rotatable shaft. Sample bearing assembly types include ball bearings and roller bearings, including needle roller bearings. One bearing assembly may be used. In other cases, two bearing assemblies or more may be used, depending on a given application. Additionally or alternatively, the coupling feature may include a cylindrical bushing and/or other component that operates to establish movement of the first pulley relative to the first rotary arm.

[0031] It will be appreciated that the coupling features and techniques herein for mounting a tensioner device to an MGU may be implemented for a variety of different tensioner device structures. In addition to the examples described above, the tensioner device may include a third rotary arm and the third “idler” pulley may be journalled to the third rotary arm. The third pulley may be adapted to apply a load on the belt, in cooperation with the second rotary arm and second pulley. For example, the second and third rotary arms may be attached to opposing ends of the first rotary arm, and a biasing element may extend between the second and third rotary arms. The second and third pulley may then apply complementary forces to the belt, in part due to the cooperative engagement of the second and third rotary arms, as established by the biasing element. In another example implementation, the first and second rotary arms may be configured to rotate about an axis of the MGU defined by the rotatable shaft. In this manner, the biasing element may also be disposed about the MGU axis, and a bushing or feature may be provided between the first and second rotary arms to establish relative movement between the arms, with the first rotary arm being moveable relative to the first pulley via the coupling feature, as described above. Other arrangements of the tensioner device are contemplated and described herein.

[0032] Reference will now be made to the accompanying drawings, which assist in illustrating various features of the present disclosure. The following description is presented for purposes of illustration and description. Furthermore, the description is not intended to limit the inventive aspects to the forms disclosed herein. Consequently, variations and modifications commensurate with the following teachings, and skill and knowledge of the relevant art, are within the scope of the present inventive aspects.

[0033] FIG. 1 depicts an example assembly 100. The assembly 100 includes a Motor Generator Unit (MGU) 104 and a tensioner device 120, such as the tensioner devices discussed above and described in greater detail below. The tensioner device 120 is shown in FIG. 1 mounted to the MGU 104 without having a housing structure that is directly fixed to the MGU 104. Rather, the MGU 104 includes a rotatable shaft 108 (shown in phantom in FIG. 1), and the tensioner device 120 is attached to the MGU 104 using the rotatable shaft 108. As described in greater detail below, one or more coupling features of the tensioner device 120 (e.g., a bearing assembly, a bushing, and so on) may be situated about the rotatable shaft 108 and allow one or more features of the tensioner device 120 to float or otherwise move relative to the rotatable shaft 108. It will be appreciated that while the rotatable shaft 108 is shown in FIG. 1 as a rotatable shaft of the MGU 104, in other cases, the rotatable shaft 108 can be a rotatable shaft associated with any of a variety of other engine, or more generally rotatable, components. In this regard, the MGU 104 is shown as an example, and the tensioner device 120 may therefore be used to couple with substantially many other rotatable components without departing from the scope of the present disclosure.

[0034] The assembly 100 is also shown to include a belt 102. The tensioner device 120 is shown in FIG. 1 in an installed configuration in which the tensioner device 120 is mounted to the MGU 104. In the installed configuration, the tensioner device 120 is configured to engage and tension the belt 102. To facilitate the foregoing, the tensioner device 120 includes a first pulley 124 with a first engagement surface 125, a second pulley 128 with a second engagement surface 129, and a third pulley 132 with the third engagement surface 133. The first pulley 124, the second pulley 128, and the third pulley 132 cooperate to establish a belt path 103 of the belt 102 through the assembly 100. The first pulley 124 may define a “drive” pulley adapted to engage and drive, or be driven by, the belt 102. The second pulley 128 and the third pulley 132 may be “idler” pulleys that help define the belt path 103 and/or be used to actively tension the belt 102.

[0035] In the example of FIG. 1, the second pulley 128 is used to actively tension the belt 102 using a biasing element 136 (shown in phantom in FIG. 1). To facilitate the foregoing, the tensioner device 120 includes a first rotary arm 140 and a second rotary arm 144. The first and second rotary arms 144, 140 may include but are not limited to pivot arms. The first and second rotary arms 144, 140 may be elongated structural members; however, this is not required. In other cases, different rotary and/or pivot structures may be used, including plates, linkages, gears and so on. The first rotary arm 140 is shown positioned about an MGU pulley axis 109 that extends a longitudinal axis of the rotatable shaft 108. The second rotary arm 144 may be moveably coupled to the first rotary arm 140 about a tensioner arm axis 135. As shown in FIG.

1, the tensioner arm axis 135 may be offset from the MGU pulley axis 109. In other examples, the tensioner arm axis 135 may be generally co-linear with the MGU pulley axis 109. The biasing element 136 may be operatively coupled to the first rotary arm 140 and the second rotary arm 144, and be arranged to bias the second rotary arm 144 toward the belt 102. The second pulley 128 may be journalled to the second rotary arm 144, and thus the bias of the second rotary arm 144 may cause the second pulley 128 to press into and tension the belt. The third pulley 132 may be journalled to the first rotary arm 140 opposite the second pulley 128, and the second pulley 128 and third pulley 132 are thus biased toward each other by biasing element 136.

[0036] The first rotary arm 140 may be supported in the assembly 100 by the rotatable shaft 108 and allowed to float or otherwise move relative to the rotation of the rotatable shaft 108. In this regard, the first rotary arm 140 may structurally support the various components of the tensioner device 120 (e.g., the pulleys 124, 128, 132, the biasing element 136, the second rotary arm 144, and so on), and without needing to turn with a rotation of the rotatable shaft 108. To facilitate the foregoing, the tensioner device 120 may include one or more coupling features that allow the first rotary arm 140 to be connected (directly or indirectly) to the rotatable shaft 108 and/or the first pulley 124 while permitting free movement of the first rotary arm 140 with respect to rotatable shaft 108 and/or the first pulley 124. [0037] With reference to FIG. 2, an exploded view of the assembly 100 is shown including the coupling features described above. In the exploded view of FIG. 2, a first coupling feature 148 and a second coupling feature 152 are shown. In some cases, first coupling feature 148 may be present without the second coupling feature 152. For example, the first coupling feature 148 can be a single bearing arranged inside of an MGU pulley (single or double row bearing), and thus the second coupling feature 152 is shown in FIG. 2 in phantom line for purposes of illustration.

[0038] In the example of FIG. 2, the first coupling feature 148 and the second coupling feature 152 are shown as bearing assemblies, such as a ball- or roller-type bearing. In this regard, the first bearing assembly or first coupling feature 148 is shown as including a first race 150a, and a second race 150b that is moveable relative to the first race 150a. Further, the second bearing assembly or second coupling feature 152 is shown as including a first race 154a, and a second race 154b that is moveable relative to the first race 154a. In other examples, one or both of the coupling features 148, 152 may be adapted as cylindrical bushings or other structures that may facilitate movement of the first rotary arm 140 relative to the rotatable shaft 108 and/or the first pulley 124.

[0039] The coupling features 148, 152 may be connected to the first pulley 124 and the first rotary arm 140. In the example of FIG. 2, the first coupling feature 148 may be substantially arranged within a through portion 141 of the first rotary arm 140 with the first race 150a connected to the rotatable shaft 108 and/or the first pulley 124 for turning with a rotation of the rotatable shaft 108, and the second race 150b connected to the first rotary arm 140. Further, the second coupling feature 152 may be substantially arranged within the through portion 141 of the first rotary arm 140 with the first race 154a connected to the rotatable shaft 108 and/or the first pulley 124 for turning with a rotation of the rotatable shaft 108, and the second race 154b connected to the first rotary arm 140. Movement of the first rotary arm 140 may therefore be defined by the operative coupling of the first and second races 150a, 150b / 154a, 154b, and is thus moveable independent of the rotation of the rotatable shaft 108, while being structurally supported in the assembly 100 by the rotatable shaft 108. The first and second coupling features 148, 152 may be restrained from axial movement along the rotatable shaft 108, which may be facilitated by a pin, restraining ring, or other feature. [0040] Turning to FIG. 3, an exploded view of the tensioner device 120 is shown. As shown in the exploded view, the first rotary arm 140 includes a first rotary arm end 142a and a second rotary arm end 142b. The second rotary arm 144 may be moveable coupled to the first rotary arm 140 at the first rotary arm end 142a. The first rotary arm end 142a may include a mounting feature 180a with a hole 181a defined therethrough. The second rotary arm 144 may define a hole 145a therethrough that is aligned with the hole 181a along the tensioner arm axis 135. A pin 182 and sleeve 183 may be provided and inserted through the holes 145a, 181a in order to connect the second rotary arm 144 to the first rotary arm 140 at the first rotary arm end 142a. The pin 182 and the sleeve 183 may be used to connect the first and second rotary arms 140, 144 to one another in a manner that allows relative movement between the first and second rotary arms 140, 144.

[0041] The first and second rotary arms 140, 144 may also be biased relative to one another, via operation of the biasing element 136. As one example, the biasing element 136 may have a first portion 137a that is connected to the first rotary arm 140 and a second portion 137b that is connected to the second rotary arm 144. The first and second portions 137a, 137b may be moved or otherwise angularly displaced relative to one another in order to store energy for subsequent release and that is adapted to bias the second rotary arm 144 for tensioning the belt 102. In the example of FIG. 3, the biasing element 136 is shown as a torsion spring, with the first and second portions 137a, 137b being respective ends of the torsion spring. In other cases, other biasing elements may be used, including leaf springs.

[0042] The second rotary arm 144 is also shown in FIG. 3 as including a hole 145b. The hole 145b may be used to facilitate attachment of the second pulley 128 to the second rotary arm 145. For example, the second pulley 128 may be journalled to the second rotary arm 144 at the hole 145b using a pulley bearing 130, as shown in FIG. 3. The pulley bearing 130 may be used to rotatably couple the second pulley 128 to the second rotary arm 144, thereby allowing the second pulley 128 to rotate as the second engagement surface 129 engages the belt 102. To facilitate the foregoing, a plug 184, a cap 186, and a pin 188 is provided. The plug 184 may seat an inner race of the pulley bearing 130 and be arranged along a first end of the second pulley 128. The cap 186 may be arranged along a second, opposing end of the second pulley 128 and close the pulley bearing 130 within the second pulley 128 with the plug 184. The pin 188 may extend through the hole 145b, and through a hole 187 of the cap 186 and a hole 185 of the plug 184, securing the second pulley 128 to the second rotary arm 144 while allowing the second pulley 128 to rotate, using the pulley bearing 130.

[0043] Also shown in FIG. 3, the third pulley 132 is attached to the first rotary arm 140 at the second rotary arm end 142b. The second rotary arm end 142b may include a mounting feature 180b with a hole 181b defined therethrough. The mounting feature 180b may seat an inner race of a pulley bearing 134. The pulley bearing 134 may be installed within the third pulley 132. A cap 189 may be arranged adjacent the third pulley 132, opposite the mounting feature 180b. A pin 190 may be provided that is extendable through a hole 191 in the cap 189 and into the hole 181b of the first rotary arm 140. Accordingly, the third pulley 132 may be secured to the first rotary arm 140 while be allowed to rotate relative thereto with the operation of the pulley bearing 134.

[0044] In FIG. 4, a front view of the assembly 100 is shown. FIG. 4 shows the tensioner device 120 mounted to the MGU 104 about the rotatable shaft 108. In the front view of FIG. 4, the assembly 100 is shown as having a damping assembly 155 (shown in phantom). The damping assembly 155 may be an optional external damping assembly that is mounted directly to the MGU 104. The damping assembly 155 may include a damping mount 156 that is configured to attach the damping assembly 155 to the MGU 104. The damping assembly 155 may pivot or otherwise move relative to the MGU 104 about the damping mount 156. To facilitate damping, the damping assembly 155 is shown as including a damping feature 158 and a guide portion 159. The guide portion 159 helps maintain a position of the damping assembly 155 relative to first rotary arm 140 and/or first pulley 124. The damping feature 158 may be adapted to contact one or both of the first rotary arm 140 and/or the first pulley 124 to generate a frictional resistance, or friction torque, therewith. The damping feature 158 can have a geometry and material adapted to tune the friction torque to a desired value.

[0045] With reference to FIG. 5, a cross-sectional view of the assembly 100 is shown, taken along line 5-5 of FIG. 4. In the cross-sectional view of FIG. 5, the tensioner device 120 is shown mounted to the MGU 104 using the first pulley 124, the first coupling feature 148, and the second coupling feature 152. The tensioner device 120 is mounted to the MGU 104 in a manner

-l i that allows the first pulley 124 to turn with a rotation of the rotatable shaft 108, while allowing the first rotary arm 140 to float or otherwise move independent of the rotation of the rotatable shaft 108.

[0046] In the example of FIG. 5, the first pulley 124 is fixed to the rotatable shaft 108. The rotatable shaft 108 may define shaft threads 110 and the first pulley 124 may define pulley threads 111. The shaft threads 110 may be arranged along the rotatable shaft 108 and along the MGU axis 109. The pulley threads 111 may be defined by a hub 113 of the first pulley 124 that is adapted to receive the rotatable shaft 108. The shaft threads 110 and the pulley threads 111 may be threadably coupled to one another in order to fix the first pulley 124 to the rotatable shaft 108. The shaft threads 110 and the pulley threads 111 may be arranged to mitigate loosening the first pulley 124 from the rotatable shaft 108 during rotation. A retaining ring, nut, splines and/or other feature may be implemented in order to secure the first pulley 124 and the rotatable shaft 108 to one another.

[0047] As one example, FIG. 5 includes a nut 114. The nut 114 may be used to axially restrain the first pulley 124 along the rotatable shaft 108. This may prevent exit of the first pulley 124 from the assembly 100 during operation. Alternatively, a series of splines 116 may also be used to facilitate connection of the first pulley 124 and the rotatable shaft 108, as shown in FIG. 5 in phantom line.

[0048] Multiple configurations of the first and second coupling features 148, 152 are contemplated and described herein, for example, with reference to FIGS. 5-9. Broadly, the coupling features 148, 152 operate to connect the first pulley 124 and the first rotary arm 140 to one another. The first pulley 124 is therefore allowed to turn with a rotation of the rotatable shaft 108, while the first rotary arm 140 is free to float or move independent of the rotation of the rotatable shaft 108 via operation of the coupling features 148, 152.

[0049] In the example of FIG. 5, the first coupling feature 148 is shown with the first race 150a connected to the rotatable shaft 108 and the second race 150b connected to the first rotary arm 140. For example, the rotatable shaft 108 may define an elongated portion 112 at or adjacent to the MGU housing and the first race 150a may be secured to the elongated portion 112, including being seated directly thereon. In this regard, the first race 150a may turn with a rotation of the rotatable shaft 108. The first rotary arm 140 may include a mounting portion 143 and the second race 150b may be secured to the mounting portion 143, including being seated directly thereon. For example, the mounting portion 143 may generally define the through portion 141 shown in FIG. 2, and include one more detents 149 therein. The mounting portion 143 may be fitted about the rotatable shaft 108 and the second race 150b or other component of the coupling feature 148 may be seated thereon. As described herein, the first and second races 150a, 150b may be races of a bearing assembly and thus moveable relative to one another. Accordingly, the first rotary arm 140 may move relative to or float with respect to the rotation of the rotatable shaft 108 while being structurally supported by the rotatable shaft 108, in light of the operation of the first coupling feature 148.

[0050] FIG. 5 also shows the second coupling feature 152 with the first race 154a connected to the first pulley 124 and the second race 154b connected to the first rotary arm 140. In the example of FIG. 5, the first race 154a may be connected to the hub 113 of the first pulley 124 and therefore be allowed to turn with a rotation of the rotatable shaft 108. In some cases, the first race 154a may be seated directly on the hub 113. The second race 154b may be connected to the mounting portion 143 of the first rotary arm 140. For example, the second race 154b may be received by one of the detents 149, and in some cases, seated directly on the mounting portion 143. Analogous to the first coupling feature 148, the first and second races 154a, 154b may be races of a bearing assembly and thus moveable relative to one another. Accordingly, the first rotary arm 140 may move relative to or float with respect to the rotation of the rotatable shaft 108 while being structurally supported by the rotatable shaft 108, in light of the operation of the second coupling features 154 in cooperation with the first coupling feature 148.

[0051] Turning to FIGS. 6-8, a detail view of the tensioner device 120 and rotatable shaft 108 is shown, according to different arrangements of the first coupling feature 148 and the second feature 152. With reference to FIG. 6, the first coupling feature 148 is shown connected to both of the rotatable shaft 108 and the first pulley 124. For example, the first race 150a may be connected to elongated portion 112 of the rotatable shaft 108 and the hub 113 of the first pulley 124. In this regard, the first race 150a, the elongated portion 112, and the hub 113 may be connected to one another and turn with the rotation of the rotatable shaft 108. [0052] To facilitate the foregoing, in the example of FIG. 6, the first race 150a may define a slot 151. The hub 113 of the first pulley 124 may be threaded onto the rotatable shaft 108 and received by the slot 151. In some cases, a locking or other anti-rotation feature may be installed to impede movement of the first race 150a relative to the hub 113, allowing the first race 150a and the hub 113 to turn with one another.

[0053] With reference to FIG. 7, each of the first coupling feature 148 and the second coupling feature 152 are shown connected to the first pulley 124. As shown in FIG. 7, the hub 113 extends along the rotatable shaft 108 and secured therewith, such as via the threadable coupling described above. The hub 113 extends along the rotatable shaft 108 and is positioned between the first coupling feature 148 and the second coupling feature 152, separating the rotatable shaft 108 from the first coupling feature 148 and the second coupling feature 152. As shown in FIG.

7, the first coupling feature 148 is connected to the hub 113 opposite the rotatable shaft 108. The first race 150a may be seated on the hub 113, including being directly mounted to the hub 113, for turning with the turning of the first pulley 124. As further shown in FIG. 7, the second coupling feature 152 is connected to the hub 113 opposite the rotatable shaft 108. The first race 154a may be seated on the hub 113, including being directly mounted to the hub 113, for turning with the turning of the first pulley 124. In some cases, a retaining ring 161 (shown in phantom in FIG. 7) may be provided to restrain axial movement of first coupling feature 148 (and/or other components of the tensioner device 120) as may be needed for a given application. Additionally or alternatively, other structures may be used to restrain axial movement, including fasteners, pins, and so on.

[0054] With reference to FIG. 8, each of the first coupling feature 148 and the second coupling feature 152 are shown connected to the first pulley 124. In the configuration of FIG. 7, the hub 113 of the first pulley 124 and the mounting portion 143 of the first rotary arm 140 extend substantially between the rotatable shaft 108 and the first and second coupling features 148, 152. In this manner, the second race 150b of the first coupling feature 148 and the second race 154b of the second coupling feature 152 are adapted to turn with the turning of the first pulley 124 while the respective first races 150a, 154a support the first rotary arm 140. [0055] For example and as shown in FIG. 8, the first pulley 124 may define a rim portion 115. The exterior of the rim portion 115 defines the first engagement surface 125, which as described above, is adapted to drive, or be driven by, the belt 102. The interior of the rim portion 115 shown in FIG. 8 is adapted for mounting the first and second coupling features 148, 152. The second race 150b may therefore be connected to the interior of the rim portion 115 for turning with the first pulley 124, including being directly connected thereto. Analogously, the second race 154b may therefore be connected to the interior of the rim portion 115 for turning with the first pulley. Each of the first race 150a of the first coupling feature 148 and the first race 150b of the second coupling feature 152 may be connected to the mounting portion 143 of the first rotary arm 140. For example, the first races 150a, 154a may be seated in detents 149, as shown in FIG. 8.

[0056] It will be appreciated that FIGS. 5-8 depicts illustrative arrangements of the first and second coupling features 148, 152 with the tensioner device 120. Other arrangements are possible and contemplated herein. For example, in some cases, the tensioner device 120 may implement damping of the first rotary arm 140 within the assembly 100. Broadly, damping may be used to control an amount of force used to move the first rotary arm 140 relative to the rotatable shaft 108. This may limit movement of the first rotary arm 140 within the assembly 100, while permitting the first rotary arm 140 to move in response to a predetermined set of criteria or conditions, such as an applied force during operation of the assembly 100.

[0057] With reference to FIG. 9, the assembly 100 is shown in a configuration to facilitate such damping. For example, the assembly 100 is shown with a damping feature 170. Broadly, the damping feature 170 operates to control the movement of the first rotary arm 140, for example, by defining a value of a force required to move the first rotary arm 140 relative to the rotatable shaft 108. In this regard, the damping feature 170 may operate to generate a friction torque between the first rotary arm 140 and the first coupling feature 148 and/or second coupling feature 152. In this regard, rather than move directly with one of the races of the coupling features 148, 152 (where the coupling features are bearings), the first rotary arm 140 may move relative to the races, and in a controlled manner, as defined by the damping feature 170. [0058] To facilitate the foregoing, the damping feature 170 is shown in FIG. 9 as including a damping plate 172, a bushing 174, and a pin 176. The damping plate 172 may include a tensioner portion 173a and an MGU portion 173b. The damping plate 172 may be defining a L- shaped cross-section with the tensioner portion 173a extending along the MGU axis 109 and the MGU portion 173b extending along a face of the MGU 104, such as along a face of an MGU housing 105. The damping plate 172 may be fixed to the MGU housing 105 via the pin 176. The pin 176 may fix the damping plate 172 to the MGU housing 105 at a single location about a circumference of the rotatable shaft 108. This may facilitate flexing of the damping plate 172 during operation of the assembly 100, and in turn facilitate the generation of friction torque as described above.

[0059] The damping plate 172 is shown connected to the first coupling feature 148 and the second coupling feature 152. For example, the second race 150b of the first coupling feature 148 and the second race 154b of the second coupling feature 152 may each be connected and/or secured to the damping plate 172. The bushing 174 be a cylindrical bushing fitted about the damping plate 172, opposing the first and second coupling features 148, 152. As further shown in FIG. 9, the mounting portion 143 of the first rotary arm 140 may be fitted about the bushing 174. The bushing 174 may be used to establish movement of the first rotary arm 140 relative to the damping plate 172. In some cases, one or more or all of the damping plate 172, the bushing 174 or the mounting portion 143 may define a textured surface. The textured surfaces may cooperate with one another to generate a friction torque with the movement of the first rotary arm 140 relative to the damping plate 172. The geometry of the surfaces may therefore be tuned in this regard in order to tune the friction torque to a desired value. Additionally or alternatively, different materials, including different combinations of materials among the damping plate 172, the bushing 174, and the mounting portion 143 may be used to tune the friction torque to a desired value.

[0060] As described herein, tensioner devices of various types and configurations may be adapted for mounting with an MGU, according to the techniques described herein. For example, coupling features may be used to mount a tensioner device about a rotational shaft of the MGU for tensioner devices having different quantities and/or arrangements of rotary arms, and other arrangements, as suited for a particular application. In this regard, FIGS. 10-13 show two alternative tensioner device structures that are directly mountable to an MGU. It will be appreciated that the tensioner devices of FIGS. 10-13 are presented for purposes of illustration. Other arrangements of tensioner devices, directly coupled with the MGU using the coupling features of the present disclosure, are contemplated herein.

[0061] With reference to FIGS. 10 and 11, a front view of an assembly 1000 is shown. The assembly 1000 includes an MGU 1004 and a tensioner device 1020. The tensioner device 1020 may be substantially analogous to the tensioner device 120 and may be adapted to engage and tension a belt 1002 associated with the MGU 1004. For example, the MGU 1004 may include a rotatable shaft 1008 (shown in phantom in FIG. 10) and the tensioner device 1020 may include a first pulley 1024 that is adapted to drive, or be driven by, a belt. The tensioner device 1020 also includes a first rotary arm 1040. The first rotary arm 1040, as described herein with reference to FIG. 11, is connected to the first pulley 1024 and/or the rotatable shaft 1008 via one or more coupling features. The first rotary arm 1040 is therefore adapted to float or move relative to the first pulley 1024 and/or the rotatable shaft 1008, while supporting various other components of the tensioner device 1020 within the system, including additional rotary arms, pulleys, biasing elements, and so on.

[0062] The tensioner device 1020 shown in FIG. 10 may be used to apply tension to multiple runs of the belt. For example, the tensioner device 1020 may include multiple pulleys that are each adapted to engage and tension the belt using one or more biasing elements of the tensioner device 1020. To facilitate the foregoing, in the example of FIG. 10, the tensioner device 1020 includes a second rotary arm 1044, a second pulley 1028, a third rotary arm 1060, a third pulley 1032, and a biasing element 1036. The first rotary arm 1040 may be situated about the rotatable shaft 1008 and have a first end 1042a and a second end 1042b. The first and second ends 1042a, 1042b may define opposing ends of the first rotary arm 1040, with the first end 1042a defining a first tensioner arm axis 1035a and the second end 1042b defining a second tensioner arm axis 1035b (e.g., as shown in FIG. 11). The second rotary arm 1044 may be moveably coupled to the first rotary arm 1040 at the first end 1042a and allowed to pivot about the first tensioner arm axis 1035a. The second rotary arm 1044 may include a second rotary arm tensioner section 1046a and a second rotary arm biasing element section 1046b. The second rotary arm tensioner section 1046a and the second rotary arm biasing element section 1046b are show in FIG. 10 as extending opposingly away from the first tensioner arm axis 1035a. Further, the third rotary arm 1060 may be moveably coupled to the first rotary arm 1040 at the second end 1042b and allowed to pivot about the second tensioner arm axis 1035b. The third rotary arm 1060 may include a third rotary arm tensioner section 1062a and a third rotary arm biasing element section 1062b. The third rotary arm tensioner section 1062a and the third rotary arm biasing element section 1062b are shown in FIG. 10 as extending opposingly away from the second tensioner arm axis 1035b.

[0063] The biasing element 1036 may generally extend between the second rotary arm 1044 and the third rotary arm 1060. In the example of FIG. 10, the biasing element 1036 includes a first portion 1037a that is connected to the third rotary arm 1060 at the third rotary arm biasing element section 1062b. The biasing element 1036 also includes a second portion 1037b that is connected to the second rotary arm 1044 at the second rotary arm biasing element section 1046b. In some cases, as shown in FIG. 10, the biasing element 1036 is a helical-type spring with the first portion 1037a and the second portion 1037b being opposing ends of a coil. In other cases, other biasing elements may be used, including leaf springs and the like.

[0064] The biasing element 1036 may be used to control the movement of the second rotary arm 1044 and the third rotary arm 1060. For example, the biasing element 1036 may encourage the second rotary arm biasing element section 1046b and/or the third rotary arm biasing element section 1062b away and/or toward one another, based in part on the spring characteristics and geometry of the biasing element 1036. Movement of the second rotary arm biasing element section 1046b and the third rotary arm biasing element section 1062b may in turn cause the second rotary arm 1044 and the third rotary arm 1060 to pivot about the first and second tensioner arm axis 1035a, 1035b, respectively. This movement may be used to apply a force to a belt that is associated with the tensioner device 1020.

[0065] For example, the second pulley 1028 may be journalled to the second rotary arm 1044 at the second rotary arm tensioner section 1046a and positioned for engagement with the belt. Further, the third pulley 1032 may be journalled to the third rotary arm 1060 at the third rotary arm biasing element section 1062b and positioned for engagement with the belt. As the second and third rotary arms 1044, 1060 pivot about the respective first and second tensioner arm axis 1035a, 1035b (via the operation of the biasing element 1036), the pulleys 1028, 1032 may move toward and impart a load to the belt for tensioning. It will be appreciated that the characteristics of the biasing element 1036, and geometry and arrangement of the pulleys 1024, 1028, 1032 and rotary arms 1040, 1044, 1060 may be tuned in order to tension the belt to a desired value.

[0066] With reference to FIG. 11, a cross-sectional view of the assembly of FIG. 10, taken along line 11-11 of FIG. 10 is shown. As shown in cross-sectional view of FIG. 10, the MGU 1004 includes the rotatable shaft 1008 with an elongated portion 1012, and threads 1010. As further shown in the cross-sectional view of FIG. 10, the tensioner device 1020 includes a hub 1013, threads 1011 and a first engagement surface 1025 of the first pulley 1024, a nut 1014, splines 1016, a mounting portion 1043 of the first rotary arm 1040, a mounting feature 1080a and a hole 1081a of the first end 1042a, a pin 1082, a sleeve 1083, a mounting feature 1080b and a hole 1081b of the second end 1042b, a pin 1064, a sleeve 1065, a first coupling feature 1048 with a first race 1050a and a second race 1050b, and a second coupling feature 1052 with a first race 1054a and a second race 1054b.

[0067] The first rotary arm 1040 is connected to the rotatable shaft 1008 and the first pulley 1024 using the first coupling feature 1048 and the second coupling feature 1052. The first and second coupling features 1048, 1052 may operate substantially analogous to the coupling features 148, 152; redundant explanation of which is omitted here for clarity. The first rotary arm 1040 is therefore arranged about the rotatable shaft 1008 for movement about the MGU axis 1009. The first rotary arm 1040 is also operable to support the second rotary arm 1044 in the tensioner device 1020. For example, the pin 1082 and the sleeve 1083 may be inserted through the second rotary arm 1044 with the pin 1082, at least partially inserted into the hole 1081a of the first rotary arm 1040 at the first end 1042a. The second rotary arm 1044 may thus be seated about the mounting feature 1080a and the pin 1082 may extend along the first tensioner arm axis 1035a to establish a pivoting relationship between the second rotary arm 1044 and the first rotary arm 1040.

[0068] Correspondingly, the first rotary arm 1040 is also operable to support the third rotary arm 1060 in the tensioner device 1020. For example, the pin 1064 and the sleeve 1065 may be inserted through the third rotary arm 1060 with the pin 1064 at least partially inserted into the hole 1081b of the first rotary arm 1040 at the second end 1042b. The third rotary arm 1060 may thus be seated about the mounting feature 1080b and the pin 1064 may extend along the second tensioner arm axis 1035b to establish a pivoting relationship between the third rotary arm 1060 and the first rotary arm 1040.

[0069] It will be appreciated that while the example of FIGS. 10 and 11 shows the first coupling feature 1048 connected to the rotatable shaft 1008 and the first rotary arm 1040, and the second coupling feature 1052 connected to the hub 1013 of the first pulley 1024 and the mounting portion 1043 of the first rotary arm 1040, other arrangements are contemplated herein. For example, the tensioner device 1020 may be adapted to a variety of different arrangements of the first and second coupling features 1048, 1052, such as those illustrated herein at FIGS. 6-9 with respect to the tensioner device 120. For example, the one or both of the coupling features 148, 152 may be seated at a detent of the rotatable shaft 1008, the hub 1013, and/or the mounting portion 1043. As another example, one or both of the coupling features 1048, 1052 may define a groove that is adapted to receive a portion of the hub 1013. As another example, the coupling features 1048, 1052 may be seated between a rim portion of the first pulley 1024 and the mounting portion 1043. As another example, the coupling features 1048, 1052 may be associated with one or more damping features, such as the damping feature 170 of FIG. 9.

[0070] As stated above, the tensioner devices of various types and configurations may be adapted for mounting with an MGU, according to the techniques described herein. For example, coupling features may be used to mount a tensioner device about a rotational shaft of the MGU for tensioner devices having different quantities and/or arrangements of rotary arms, and other arrangements, as suited for a particular application. With reference to FIGS. 12-14, another example arrangement of a tensioner device, directly coupled with the MGU using the coupling features of the present disclosure, is shown.

[0071] Turning to FIG. 12, a front view of an assembly 1200 is shown. The assembly 1200 includes an MGU 1204 and a tensioner device 1220. The tensioner device 1220 may be substantially analogous to the tensioner device 120 and may be adapted to engage and tension a belt 1202 associated with the MGU 1204. For example, the MGU 1204 may include a rotatable shaft 1208 (shown in phantom in FIG. 12) and the tensioner device 1220 may include a first pulley 1224 that is adapted to drive, or be driven by, the belt. [0072] The tensioner device 1220 shown in FIG. 12 may be used to apply tension to multiple runs of the belt. For example, the tensioner device 1220 may include multiple pulleys that are each adapted to engage and tension the belt using one or more biasing elements of the tensioner device 1220. To facilitate the foregoing, in the example of FIG. 12, the tensioner device 1220 includes a first rotary arm 1240, a second rotary arm 1244, a second pulley 1228, a third pulley 1232, and a biasing element 1236. As shown in greater detail in FIG. 13, the first and second rotary arms 1240, 1244 are connected to the rotatable shaft 1208 and the first pulley 1224 using one or more coupling features. Broadly, the coupling features may allow the first and second rotary arms 1240, 1244 to move relative to one another, and relative to the rotatable shaft 1208 and the first pulley 1224. The first and second rotary arms 1240, 1244 may in turn support other components of the tensioner device 1220, such as pulleys, biasing elements, and so on, while floating, rotationally relative to the rotatable shaft 1208.

[0073] In the example of FIG. 12, the second pulley 1228 is journalled to the second rotary arm 1244 and positioned to engage a belt. The second pulley 1228 may be journalled to the second rotary arm 1244 opposite the association of the second rotary arm 1244 and the rotatable shaft 1208. Further, the third pulley 1232 may be journalled to the first rotary arm 1240 and positioned to engage a belt. The third pulley 1232 may be journalled to the first rotary arm 1240 opposite the association of the first rotary arm 1240 and the rotatable shaft 1208.

[0074] The biasing element 1236 may be adapted to encourage movement of the first and second rotary arms 1240, 1244 away and/or toward one another. This movement of the rotary arms 1240, 1244 may be used to manipulate the second and third pulley 1228, 1232 toward the belt for tensioning the belt. For example, the biasing element 1236 may generally extend between the first rotary arm 1240 and the second rotary arm 1244. In the example of FIG. 12, the biasing element 1236 includes a first portion 1237a that is connected to the first rotary arm 1240. The biasing element 1236 also includes a second portion 1237b that is connected to the second rotary arm 1244. In some cases, as shown in FIG. 12, the biasing element 1236 is a helical-type spring with the first portion 1237a and the second portion 1237b being opposing ends of a coil. In other cases, other biasing elements may be used, including leaf springs and the like. The biasing element 1236 may also be integrated substantially within the first pulley 1224 and about the rotatable shaft 1208, as shown in FIG. 14 A. As the first and second rotary arms 1240, 1244 are moved about the rotatable shaft 1208 (via the operation of the biasing element 1236), the pulleys 1228, 1232 may move about a tensioner arm axis that itself may be, in one example, substantially co-linear with an MGU axis 1209 and impart a load to the belt for tensioning. It will be appreciated that the characteristics of the biasing element 1236, and geometry and arrangement of the pulleys 1224, 1228, 1232 and rotary arms 1240, 1044 may be tuned in order to tension the belt to a desired value.

[0075] With reference to FIG. 13, a cross-sectional view of the assembly of FIG. 12, taken along line 13-13 of FIG. 12 is shown. As shown in cross-sectional view of FIG. 13, the MGU 1204 includes the rotatable shaft 1208 with an elongated portion 1212, and threads 1210. The rotatable shaft may rotate about the MGU axis 1209. As further shown in the cross-sectional view of FIG. 13, the tensioner device 1220 includes a hub 1213, threads 1211 and a first engagement surface 1225 of the first pulley 1224, a nut 1214, splines 1216, a mounting portion 1243, a mounting feature 1280a and a hole 1281a of the first rotary arm 1240, a mounting portion 1247, a mounting feature 1280b and a hole 1281b of the second rotary arm 1244, a pulley bearing 1230, a cap 1286, a pin 1288, a pulley bearing 1234, a cap 1289, a pin 1290, a first coupling feature 1248 with a first race 1250a and a second race 1250b, and a second coupling feature 1248 with a first race 1250a and a second race 1250b.

[0076] In this regard, the tensioner device 1220 may be substantially analogous to the tensioner device 120 of FIG. 5 and the tensioner device 1020 of FIG. 10; redundant explanation of which is omitted here for clarity. Notwithstanding the foregoing similarities, the tensioner device 1220 further includes a third coupling feature 1260. The third coupling feature 1260 may be used to establish movement of the second rotary arm 1244 relative to the first rotary arm 1240. In the example of FIG. 11, the third coupling feature 1260 is shown as a cylindrical bushing that is arranged between the first and second rotary arms 1240, 1244 and about the rotatable shaft 1208. For example, the first rotary arm 1240 may define the mounting portion 1243 that may be arranged about the rotatable shaft 1208, and the second rotary arm 1244 may define a mounting portion 1247 that may be arranged about the rotatable shaft 1208, and may define an annular gap with the mounting portion 1243. Within the annular gap, the third coupling feature 1260 may be installed with opposing cylindrical surfaces arranged for contact with the mounting portions 1243, 1247. In some cases, one or both of the opposing cylindrical surfaces may be a textured surface or otherwise be tuned to facilitate damping. A retaining ring or other feature may be implemented to impede axial movement of the third coupling feature 1260 along the rotatable shaft 1208.

[0077] It will be appreciated that while the third coupling feature 1260 is shown in FIG. 13 as a cylindrical bushing, other structures are contemplated herein. For example, the third coupling feature 1260 may be defined as bearing-type structure, which may be similar to the bearing assemblies shown in FIG. 13 for the first and second coupling features 1248, 1252. The third coupling feature 1260 may also be used to provide damping. As one example, the third coupling feature 1260 may include a material choice and/or a surface texture tuned to induce a desired friction torque relative to the first and second rotary arms 1240, 1244.

[0078] It will be appreciated that while the example of FIG. 12 shows the first coupling feature 1248 connected to the rotatable shaft 1208 and the first rotary arm 1240, and the second coupling feature 1252 connected to the hub 1213 of the first pulley 1224 and the mounting portion 1243 of the first rotary arm 1040, other arrangements are contemplated herein. For example, the tensioner device 1220 may be adapted to a variety of different arrangements of the first and second coupling features 1248, 1252, such as those illustrated herein at FIGS. 6-9 with respect to the tensioner device 1220. For example, the one or both of the coupling features 1248, 1252 may be seated at a detent of the rotatable shaft 1208, the hub 1213, and/or the mounting portions 1243, 1247. As another example, one or both of the coupling features 1248, 1252 may define a groove that is adapted to receive a portion of the hub 1213. As another example, the coupling features 1248, 1252 may be seated between a rim portion of the first pulley 1224 and the mounting portion 1243. As another example, the coupling features 1248, 1252 may be associated with one or more damping features, such as the damping feature 170 of FIG. 9.

[0079] As one example modification of the tensioner device 1220, a biasing element may be arranged substantially within the first pulley 1224. For example, FIG. 14A shows a detail view of an example modification of the tensioner device 1220 in which the biasing element 1236 is positioned substantially within the first pulley 1224 for biasing the first and second rotary arms 1240, 1244 relative to one another to define an assembly 1200'. In the example of FIG. 14 A, the mounting portion 1243 defines a first landing, or surface, 1266a. The mounting portion 1247 defines a second landing, or surface, 1266b. The first portion 1237a of the biasing element 1236 is seated at the first landing, or surface, 1266a and the second portion 1237b of the biasing element 1236 is seated at the second landing, or surface, 1266b. The landings 1266a, 1266b may catch the respective first and second portions 1237a, 1237b such that the first portion 1237a is generally fixed to the mounting portion 1243 of the first rotary arm 1240 and the second portion 1237b is generally fixed to the mounting portion 1247 of the second rotary arm 1244. The first and second portions 1237a, 1237b move relative to one another according to a spring coefficient or other parameter in order to store and release a biasing force responsive to the relative movement. The biasing element 1236 may therefore be tuned to bias the first and second rotary arms 1240, 1244 as the first and second rotary arms 1240, 1244 move relative to one another.

[0080] As one example modification of the tensioner device 1220, each of the coupling features 1248, 1252 and the first pulley 1224 may be coupled with the rotatable shaft 1208. The first and second rotary arms 1240, 1244 may be attached to respective ones of the coupling features 1248, 1252. For example, FIG. 14B shows a detail view of an example modification of the tensioner device 1220 in which the coupling features 1248, 1252 and the first pulley 1224 are coupled to the rotatable shaft 1208 along the elongated portion 1212 to define an assembly 1200". In the example of FIG. 14B, the first pulley 1224 is coupled to the elongated portion 1212 and interposed between the coupling features 1248, 1252. The first coupling feature 1248 is positioned adjacent the MGU 1204 and the second coupling feature 1252 is positioned adjacent a free end of the rotatable shaft 1208, opposite the first coupling feature 1248. The first coupling feature 1248 is coupled to both the first rotary arm 1240 and the rotatable shaft 1208 in order to establish a movable coupling between the first rotary arm 1240 and the rotatable shaft 1208. The second coupling feature 1252 is coupled to both the second rotary arm 1244 and the rotatable shaft 1208 in order to establish a movable coupling between the second rotary arm 1244 and the rotatable shaft 1208.

[0081] Other examples and implementations are within the scope and spirit of the disclosure and appended claims. For example, features implementing functions may also be physically located at various positions, including being distributed such that portions of functions are implemented at different physical locations. Thus, the foregoing descriptions of the specific examples described herein are presented for purposes of illustration and description. They are not targeted to be exhaustive or to limit the examples to the precise forms disclosed. It will be apparent to one of ordinary skill in the art that many modifications and variations are possible in view of the above teachings.