WO2018129613A1

WO2018129613A1 - Attachment of a pulley device to a shaft using a jam collar with a wedging structure

Info

Publication number: WO2018129613A1
Application number: PCT/CA2018/050016
Authority: WO
Inventors: Jordan COOK; Evan Hurry
Original assignee: Litens Automotive Partnership
Priority date: 2017-01-16
Filing date: 2018-01-09
Publication date: 2018-07-19

Abstract

In an aspect, a pulley device for a drive shaft including, including a pulley, a shaft adapter having a bore extending from a first to a second axial end, and a shaft adapter shoulder proximate the first axial end, a first, threaded shaft adapter connection structure in the bore, and a second shaft adapter connection structure. The pulley device further includes a jam collar having a jam collar wedging structure. The pulley device further includes a threaded fastener having a fastener wedging structure. The fastener wedging structure engages the jam collar wedging structure to drive frictional engagement between a jam collar radially outer structure and the second shaft adapter connection structure, and to drive frictional engagement between a jam collar axial connection structure and a shaft connection structure on the drive shaft, thereby locking the shaft and the shaft adapter against relative rotation in a second rotational direction.

Description

ATTACHMENT OF A PULLEY DEVICE TO A SHAFT USING A

JAM COLLAR WITH A WEDGING STRUCTURE

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority to and the benefit of U.S. Provisional Patent Application No. 62/446,589 filed January 16, 2017, the contents of which are incorporated herein in their entirety.

FIELD

[0002] This disclosure relates to field of pulley devices such as fixed pulleys, isolators and TVDs (Torsional Vibration Dampers), and in particular to a method of attaching an isolator to a drive shaft, for example an engine crankshaft or a motor-generator unit (MGU) shaft.

BACKGROUND

[0003] Isolators are known devices that are installed in accessory drive systems, on engine crankshafts and/or on accessory drive shafts for reducing the transmission of torsional vibrations from the crankshaft to a belt driven by the crankshaft and/or from the belt to the accessory drive shaft. In some instances where the engine is a hybrid engine that incorporates an MGU, the accessory drive system is operated in a first mode where the accessory drive belt is driven by the engine crankshaft and in turn drives the accessories, and in a second mode where the MGU drives the belt, which in turn drives the accessories (referred to as ISAF - Idle/Stop Accessory Function) and/or drives the engine crankshaft (such as during a BAS (Belt-Alternator Start) event, or a boost event where the MGU supplies additional power to the engine via the belt). In such systems, the isolator operates to transfer torque from the belt to a shaft in one mode, and operates to transfer torque from the shaft to the belt in the other mode. In order to ensure that the isolator remains fixed to the shaft to which it is installed, it is sometimes simply welded to the shaft. Welding is problematic, however, as it is time consuming and it requires grinding or the like in order to remove the isolator from the shaft, which will likely damage both the shaft and the isolator, thereby making the process of replacing a worn or defective isolator time consuming and expensive. In other cases an isolator may be keyed to the shaft. While a keyed arrangement is releasable, thereby facilitating removal and replacement of the isolator as needed, keying can be troublesome since some play can develop or is present from the beginning between the key and the key-receiving slot in the shaft, and/or between the key and the key-receiving slot in the isolator's shaft adapter.

[0004] It would be advantageous to be able to provide a connection that avoids damage to at least one of the shaft and the isolator during removal of the isolator from a drive shaft, such as the engine's crankshaft or an accessory shaft.

SUMMARY

[0005] In an aspect, there is provided a pulley device assembly. The pulley device includes a pulley and has a shaft adapter that has a bore extending from a first axial end of the shaft adapter to a second axial end of the shaft adapter. The pulley device further includes a shaft adapter shoulder proximate the first axial end, a first shaft adapter connection structure which is threaded and is in the bore, and a second shaft adapter connection structure. The drive shaft includes a shaft axial end, a shaft shoulder, a first shaft connection structure which is threaded, a second shaft connection structure which is threaded and a third shaft connection structure which is an axial end face of the drive shaft, wherein the first shaft adapter connection structure and the first shaft connection structure are engaged with one another to provide a first non-destructively releasable connection. The pulley device further includes a jam collar having a jam collar wedging structure that is generally conical, a jam collar radially outer structure, and a jam collar axial connection structure. The pulley device further includes a threaded fastener having a threaded fastener wedging structure that is generally conical, and a second fastener connection structure which is threaded and which engages the second shaft connection structure to provide a second non-destructively releasable connection. The threaded fastener wedging structure engages the jam collar wedging structure to drive frictional engagement between the jam collar radially outer structure and the second shaft adapter connection structure, and to drive frictional engagement between the jam collar axial connection structure and the third shaft connection structure, thereby locking the shaft and the shaft adapter against relative rotation in a second rotational direction.

[0006] In another aspect, there is provided a method of attaching a pulley device to a drive shaft. The pulley device includes a pulley and has a shaft adapter that has a bore extending from a first axial end of the shaft adapter to a second axial end of the shaft adapter. The pulley device further includes a shaft adapter shoulder proximate the first axial end, a first shaft adapter connection structure which is threaded and is in the bore, and a second shaft adapter connection structure, the drive shaft including a shaft axial end, a shaft shoulder, a first shaft connection structure which is threaded, and a second shaft connection structure which is threaded and a third shaft connection structure which is at the shaft axial end. The method comprises:

a) inserting the shaft axial end into the bore and causing relative rotation between the shaft and the shaft adapter in a first rotational direction to engage the first shaft adapter connection structure and the first shaft connection structure with one another to provide a first non-destructively releasable connection;

b) inserting a jam collar into the bore, wherein the jam collar has a jam collar wedging structure that is generally conical, a jam collar radially outer structure, and a jam collar axial connection structure;

c) providing a threaded fastener with a fastener wedging structure and a second fastener connection structure; and

d) connecting the second fastener connection structure to the second shaft connection structure to provide a second non-destructively releasable connection, such that the fastener wedging structure engages the jam collar wedging structure to generate a selected first frictional force between the jam collar radially outer structure and the second shaft adapter connection structure, and a selected second frictional force between the jam collar axial connection structure and the third shaft connection structure. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] The foregoing and other features and advantages will be apparent from the following description of the disclosure as illustrated in the accompanying drawings. The accompanying drawings, which are incorporated herein and form a part of the specification, further serve to explain the principles of the disclosure and to enable a person skilled in the pertinent art to make and use the disclosure. The drawings are not to scale.

[0008] Figure 1 is a side view of an engine in a vehicle containing an isolator on a shaft of an MGU (motor generator unit), according to non-limiting embodiments.

[0009] Figure 2 is a perspective view of an example of the isolator shown in Figure 1.

[0010] Figure 3 is a perspective exploded view of the isolator shown in Figure 2, including a shaft adapter and connected to a shaft of the MGU, with a portion cut away.

[0011] Figures 4-14 are perspective cutaway views that illustrate the assembling of the isolator to the shaft of the MGU.

[0012] Figure 15 is a sectional side view of a portion of the assembly formed by the isolator and the shaft.

[0013] Figure 16 is a sectional side view of the assembly formed by the isolator and the shaft, showing forces and torques along the length of the shaft adapter.

[0014] Figure 17 is a graph showing average breakaway torques for assemblies as described herein and for assemblies that do not incorporate a jam collar as described herein.

[0015] Figure 18 is a graph showing breakaway torque relative to angular displacement for an assembly as described herein and for an assembly that does not incorporate a jam collar as described herein.

[0016] Figure 19 is a sectional exploded elevation view of a portion of the assembly shown in Figure 3.

[0017] Figure 20 is a sectional view of a jam collar that is part of the assembly shown in Figure 3 illustrating forces acting thereon. DETAILED DESCRIPTION OF EXAMPLE EMBODIMENTS

[0018] Specific embodiments of the present disclosure are now described with reference to the figures, wherein like reference numbers indicate identical or functionally similar elements. The following detailed description is merely an example and is not intended to limit the disclosure or the application and uses of the disclosure. Furthermore, there is no intention to be bound by any expressed or implied theory presented in the preceding technical field, background, brief summary or the following detailed description.

[0019] Reference is made to Figure 1 , which shows an isolator 10 for transferring power in an accessory drive system 20, between an endless drive member 30, such as an accessory drive belt, that is driven by a crankshaft pulley 32 mounted on a crankshaft 34 of an engine 40, and a shaft 42 of an MGU (motor generator unit) 44. The isolator 10 is shown as being mounted on the drive shaft 42 of the MGU 44, and serves to isolate the MGU 44 from torsional vibrations in the endless drive member 30 that commonly occur in internal combustion engines. Although shown as mounted on the drive shaft 42, it will be understood that the isolator 10 could additionally or alternatively be mounted on any other suitable drive shaft, such as the crankshaft 34. The endless drive member 30 may be referred to as a belt for readability, however, it will be understood that any other suitable endless drive member may be used. The accessory drive system 20 may include other accessory drive shafts including, for example, the drive shaft 46 of an air conditioning compressor 48.

[0020] The isolator 10 is useful in any engine, but is particularly useful in an engine that incorporates a BAS (belt-alternator start) system, in which the engine 40 is initially started normally (e.g. using a starter motor) but is shut down for brief periods (e.g. while the vehicle is at a stoplight) and then restarted by driving the crankshaft 34 via the belt 30. The belt 30 would be driven by the MGU 44. Alternatively, the MGU 44 may be replaced by an alternator and a separate motor may be used to drive the belt 30 during BAS events. Thus, torque is sometimes transferred from the belt 30 to the MGU drive shaft 42 through the isolator 10, and is sometimes transferred to the belt 30 from the MGU drive shaft 42 through the isolator 10. BAS technology is becoming increasingly common in an effort to increase vehicle fuel economy and reduce emissions. [0021] An example isolator suitable for use in the accessory drive system 20 is shown in Figures 2 and 3. The isolator 10 includes a shaft adapter 52, a rotary drive member 54, and a spring arrangement 56. The shaft adapter 52 is used to mount the isolator 10 to the drive shaft 42, so as to form an assembly between isolator 10 and the drive shaft 42. An example shaft adapter 52 is described further below. The rotary drive member 54 may be any suitable type of rotary drive member such as a pulley. The rotary drive member 54 may be referred to as a pulley 54 for readability, in much the same way that the endless drive member 30 may be referred to as a belt 30, however it will be understood that any other suitable rotary drive member may be used.

[0022] The spring arrangement 56 includes at least one spring. In the example shown, the spring arrangement includes two primary, outer, arcuate, helical compression springs 58 and two secondary, inner, arcuate, helical compression springs 60 that are nested in the two outer springs 58 and operate in parallel with the springs 58. The springs 58 and 60 may generally be arranged to exhibit polar symmetry about the axis of rotation of the isolator 10, shown at A. Other types of springs may alternatively or additionally be used in the spring arrangement 56.

[0023] The springs 58 and 60 may sit inside a spring shell 62 that is formed from spring shell portions 62a, 62b, 62c and 62d. In the example shown, the spring shell 62 forms part of the pulley 54. The outer springs 58 each have a first spring end 58a and a second spring end 58b, while the inner springs 60 each have a first spring end shown at 60a and a second spring end 60b.

[0024] In the example shown, the shaft adapter 52 has a spring driver member 64 that has a plurality of first adapter spring drive surfaces 66 and second adapter drive surfaces 68 thereon for engagement with the springs 58 and 60. The pulley 54 includes a plurality of first pulley spring drive surfaces 70 and second pulley spring drive surfaces 72, for engagement with the ends 58a and 60 of the springs 58 and 60.

[0025] In the first mode described above for the accessory drive system 20, torque is applied to the pulley 54 from the belt 30 and may then be transferred from the pulley 54 through the spring arrangement 56 into the shaft adapter 52, and finally from the shaft adapter 52 into the drive shaft 42. In the second mode described above, torque is applied to the shaft adapter 52 from the drive shaft 42 of the MGU 44 (Figure 1 ) and is applied from the shaft adapter 52 through the spring arrangement 56 to the pulley 54, and from the pulley 54 to the belt 30. In the first mode, torque 58a is transmitted from the first pulley spring drive surfaces 70 to the first spring ends (and 60a if the torque is sufficiently high), and from the second spring ends 58b (and 60b if the torque is high enough) to the first adapter spring drive surfaces 68, into the shaft adapter 52 and into the shaft 42. In the second mode, torque is transmitted from the shaft 42, into shaft adapter 52, from the second adapter spring drive surfaces 66 which are on the shaft adapter 52 into the second spring ends 58b (and 60b if the torque is sufficiently high), and from the first spring ends 58a (and 60a if the torque is high enough) to the second pulley spring drive surfaces 72.

[0026] The pulley 54 moves rotationally relative to the shaft adapter 52 in one direction or the other based on which way torque is being transferred. A bushing 74 may be provided between a pulley rotation surface 76 and a shaft adapter rotation surface 78.

[0027] Other components such as a dust cover, thrust washers, damping members, bushings and the like, are shown and may be provided as necessary for the operation of the isolator 10. Apart from the description below relating to the structure of the shaft adapter 52 and its mounting to the drive shaft 42, a suitable pulley device may, for example be as shown and described in PCT publication WO2012061930A1 (which shows a pulley device incorporating a helical torsion spring), or as shown and described in PCT publication WO2015027325A1 (which shows a pulley device incorporating arcuate helical compression springs), the contents of both of which are incorporated fully herein by reference. Accordingly, for readability, the isolator 10 as herein represented is generalized, that is presented without limiting detail, as shown for example in Figure 4.

[0028] Reference is now made to Figures 4-14. The drive shaft 42 is shown in Figure 4 in section, and the completed assembly of the drive shaft 42 and the isolator 10 is shown in section in Figure 14. The drive shaft 42 has a shaft axial end 80, a shaft shoulder 82, a first shaft connection structure 84 and a second shaft connection structure 86. The first shaft connection structure 84 includes an outside surface of the shaft 42 and is threaded with, for example, a right hand thread (as is typical for threaded elements). The second shaft connection structure 86 may include a radially inner surface of the shaft 42, and is also threaded. The second shaft connection structure 86 is provided with a thread oriented in the opposite direction to the first shaft connection structure 84. Accordingly, the second shaft connection structure 86 is provided with a left hand thread in the example shown. In Figures 4-14 the threads of the first and second shaft connection structures 84, 86 are represented without showing actual thread flights. The drive shaft 42 may further include a shaft tool receiving structure 88, which may, for example, be a hex- shaped aperture at the axial end 80, which receives a shaft tool 90 (see Figure 7). As presented, the drive shaft 42 also supports a bearing member 92.

[0029] For simplicity and ease of illustration, the isolator 10 as shown in Figures 4-14 does not present the various components enclosed by the spring shell 62. As a result, the simplified isolator 10 as presented includes the shaft adaptor 52, the rotary drive member 54 and the spring shell 62.

[0030] The shaft adapter 52 has a bore 94 extending from a first axial end 96 of the shaft adapter 52 to a second axial end 98 of the shaft adapter 52. The isolator 10 further includes a shaft adapter shoulder 100 proximate the first axial end 96, and a first shaft adapter connection structure 102 that is in the bore 94. The first shaft adapter connection structure 102 is threaded and is configured to mate with the first shaft connection structure 84 (and which may therefore also have a right hand thread), so as to form a first, nondestructive^ releasable connection between the shaft adapter 52 and the shaft 42, as shown in Figure 5. With this thread arrangement, relative rotation of the shaft 42 and the shaft adapter 52 in a first rotational direction (e.g. turning the shaft adapter 52 clockwise relative to the shaft 42 in the view shown in Figure 5) tightens the first connection therebetween, while relative rotation of the shaft 42 and the shaft adapter 52 in a second rotational direction (e.g. turning one of the shaft 42 and the shaft adapter 52 counterclockwise relative to the other of the shaft 42 and the shaft adapter 52 in the view shown in Figure 5), loosens the connection therebetween.

[0031] The shaft adapter 52 also provides a second shaft adapter connection structure 104 in the bore 94. The second shaft adapter connection structure 104 may be configured as an unthreaded extension of the first shaft adapter connection structure 102. As shown in Figure 6, the second shaft adapter connection structure 104 is configured to cooperate with a jam collar 1 10 and a threaded fastener 1 12 (best seen in the assembled side sectional view of Figure 15) to provide a second connection between the shaft adapter 52 and the shaft 42. In the embodiment shown in Figures 4-14, the second connection is, like the first connection, non-destructively releasable.

[0032] Continuing with Figure 15, the jam collar 110 has a first jam collar connection structure 1 14 (which may be referred to as a jam collar radially outer connection structure 1 14) that engages the second shaft adapter connection structure 104, and a second jam collar connection structure 1 16 (which may be referred to as a jam collar axial connection structure 1 16) that engages an axial end face 1 18 of the shaft axial end 80 of the shaft 42. The jam collar 1 10 also provides a third jam collar connection structure 120 (which may be referred to as a jam collar wedging structure 120) which cooperates with a first fastener connection structure 122 of the threaded fastener 1 12 (which may be referred to as a threaded fastener wedging structure 122 and which is generally conical). The jam collar wedging structure 120 has a generally conical shape.

[0033] The threaded fastener 1 12 provides a second fastener connection structure 124 that is threaded and is configured to mate with the second shaft connection structure 86 (and which may therefore also have a left hand thread), so as to form the second, non- destructively releasable connection between the shaft adapter 52 and the shaft 42. A tightening engagement at the second fastener connection structure 124 and the second shaft connection structure 86 serves to frictionally lock the interface between the second shaft adapter connection structure 104 of the shaft adapter 52 and the first jam collar connection structure 1 14 of the jam collar 1 10. This is achieved by virtue of the wedging effect formed at the third jam collar connection structure 120 of the jam collar 1 10 and the first fastener connection structure 122 of the threaded fastener 1 12 which provides a selected first friction force between the jam collar radially outer connection structure 1 14 and the second shaft adapter connection structure 104, and a second selected frictional force between the jam collar axial connection structure 1 16 and the third shaft connection structure 118.

[0034] As shown, the threaded fastener 1 12 further includes a fastener tool receiving structure 130 (e.g. a hex-shaped aperture) that is shaped to receive a fastener tool 132 (Figure 12).

[0035] Referring to Figure 6, the shaft adapter 52 may further include a shaft adapter tool receiving structure 126, which may, for example, include a toothed portion that engages a shaft adapter tool 128 (Figure 7) that has a mating toothed portion. The use of the shaft and shaft adapter tool receiving structures 88 and 126 permit elements to be tightened or loosened relative to one another as needed during assembling or disassembling of the assembly.

[0036] Figures 4-14 illustrate a method of assembling the assembly formed by the shaft 42 and the shaft adapter 52 and therefore of the assembly formed by the shaft 42 and the isolator 10. With reference to Figure 4, the shaft 42 and the bearing member 92 are shown in isolation. In the step shown Figure 5, the shaft adapter 52 and therein the isolator 10 is mounted to the shaft 42 by inserting the shaft axial end 80 into the bore 94 and causing relative rotation between the shaft 42 and the shaft adapter 52 in the first rotational direction to engage the first shaft adapter connection structure 102 and the first shaft connection structure 84 with one another to provide the first connection.

[0037] In the step shown in Figure 6, the jam collar 1 10 is inserted into the opposing end of the bore 94 of the shaft adapter 52. The jam collar 1 10 is positioned to engage the first jam collar connection structure 1 14 with the second shaft adapter connection structure 104, and the second jam collar connection structure 1 16 with the axial end face 1 18 of the shaft axial end 80 of the shaft 42.

[0038] In the step shown in Figure 7, the shaft adapter tool 128 is first inserted into the bore 94 of the shaft adapter 52. The shaft adapter tool 128 is seated within the bore 94 such that the toothed portion of the shaft adapter tool 128 engages the mating toothed portion of the shaft adapter tool receiving structure 126, therein rotationally locking together the shaft adapter tool 128 and the shaft adapter 52. Next, the shaft tool 90 is inserted through an aperture in the shaft adapter tool 128. The shaft tool 90 is seated such that it engages the shaft tool receiving structure 88 at the axial end 80 of the shaft 42. As such, the shaft tool 90 is rotationally locked relative to the shaft 42.

[0039] In the step shown in Figure 8, the first connection, that is the connection between the shaft adapter 52 and the shaft 42 at the first shaft connection structure 86 and the first shaft adapter connection structure 102 is tightened by rotating the shaft adapter tool 128 relative to the shaft tool 90. With the right-hand thread provided at the first connection, the shaft adapter tool 128 is shown as being rotated clockwise relative to the stationary shaft tool 90. The extent to which the first connection is tightened is determined by the desired compression force to be established between the shaft shoulder 82 and the shaft adapter shoulder 100, through the intermediate bearing member 92 arranged therebetween.

[0040] In the step shown in Figure 9, the shaft adapter tool 128 and the shaft tool 90 are removed, and as shown in Figure 10, the threaded fastener 1 12 is inserted into the bore 94 of the shaft adapter 52. The threaded fastener 1 12 is positioned to engage the second fastener connection structure 124 with the corresponding second shaft connection structure 86 on the shaft axial end 80 of the shaft 42.

[0041] Figure 1 1 illustrates reinsertion of the shaft adapter tool 128 to rotationally lock the shaft adapter tool 128 relative to the shaft adapter 52. Next, the fastener tool 132 is inserted through the aperture in the shaft adapter tool 128. The fastener tool 132 is seated such that it engages the fastener tool receiving structure 130 provided on the threaded fastener 1 12. As such, the fastener tool 132 is rotationally locked relative to the threaded fastener 1 12.

[0042] In the step shown in Figure 12, the second connection, that is the connection between the shaft adapter 52 and the shaft 42 via the threaded fastener 1 12 and jam collar 110 is tightened by rotating the fastener tool 132 relative to the shaft adapter tool 128. With the left-hand thread provided at the second connection, the fastener tool 132 is shown as being rotated counter-clockwise relative to the stationary shaft adapter tool 128.

[0043] Once the shaft adapter and fastener tools 128, 132 are removed (Figure 13), an end plug 134 (see Figure 14) may be inserted in the bore 94 to inhibit entry of dust or other contaminants. With the completed assembly arranged in this way, relative rotation of the shaft 42 and the shaft adapter 52 in the first rotational direction serves to tighten the first connection. Should there be relative rotation of the shaft 42 and the shaft adapter 52 in a second rotational direction that is opposite to the first rotational direction, the engagement of the first jam collar connection structure 114 with the second shaft adapter connection structure 104, and therein the threaded fastener 1 10 results in a tightening of the second connection.

[0044] The disassembling of the assembly formed in Figure 14 is carried out easily by reversing the actions carried to create the assembly. Thus the end plug 134 is removed, the tools 128 and 132 are used to loosen the second connection, while the tools 128 and 90 are used to loosen the first connection.

[0045] Shown in Figure 16 are torque values used in some embodiments at different stages of assembling, and some forces that exist in the completed assembly. The torque curve shown at 200, presents the torque distribution during the assembly of the first connection at the step shown in Figure 8. In the completed assembly, the compressive load distribution and break-away torque of the first connection are presented at the curves shown at 210 and 220, respectively. The torque curve shown at 230, presents the torque distribution during the assembly of the second connection at the step shown in Figure 12. In the completed assembly, the total compressive load distribution and break-away torque are presented at the curves shown at 240 and 250, respectively.

[0046] Figures 17 and 18 show a comparison of a connection structure in accordance with the present disclosure and a standard bolted connection. Figure 17 shows a distribution curve 300 of the breakaway torque of several samples of a bolted connection that does not incorporate the jam collar 1 10, and a distribution curve 302 of the breakaway torque of several samples of a connection in accordance with the present disclosure, where the breakaway torque is the torque needed to loosen the connection with the drive shaft 42. As can be seen from curve 300, the average breakaway torque for the bolted connection without the jam collar 1 10 is about 120Nm, whereas the average breakaway torque for a connection in accordance with the present disclosure is about 134Nm. Figure 18 shows the breakaway torque over a range of angular displacements between the shaft adapter and the shaft 42 for both a bolted connection without the jam collar 1 10 (shown at 304) and for a connection in accordance with the present disclosure (shown at 306). As can be seen, as the shaft adapter rotates relative to the shaft in a bolted connection without the jam collar, the breakaway torque (see curve 304) generally oscillates but drops and then drops to zero over a short angular displacement range. By contrast, for the connection according to the present disclosure (see curve 306) the breakaway torque oscillates, generally decreasing, but then increases again and remains above about 36 Nm over a large angular range.

[0047] Figure 19 provides an exploded view of components of the assembly in accordance with the present disclosure, and Figure 20 shows a sectional view of the jam collar 1 10 with the forces acting thereon. The theoretical torque holding capacity for the assembly can be calculated as follows:

Fn:=Fcl x cos(a)

Fn2:=Fcl x sin(a)

Ff:=MU x Fn Ff2:=MU x Fn2

T:=Ff x r T2:=Ff2 x r2

[0048] The theoretical torque holding capacity for the assembly is given by the smaller of T and T2, where T is the resistive torque applied between the jam collar 1 10 and the shaft adapter 52 for resisting slippage of the jam collar 1 10 relative to the shaft adapter 52, and T2 is the resistive torque applied between the jam collar 1 10 and the shaft end 80 for resisting slippage of the shaft end 80 relative to the jam collar 1 10. Ff and Ff2 are the forces of friction at the interfaces between the jam collar 1 10 and the shaft adapter 52, and between the jam collar 110 and the shaft end 80, respectively. It is the frictional forces Ff and Ff2 that result in the resistive torques T and T2. MU is the coefficient of friction between the jam collar 110 and the shaft adapter 52, and is also the coefficient of friction between the jam collar 110 and the shaft end 80. r is the radius of the outer face of the jam collar, as shown in Figure 19. r2 is the radius at the radially innermost end of the threaded fastener wedging structure 122 as shown in Figure 19. a is the angle of the jam collar wedging structure 120 relative to the axis A as shown in Figure 19 (or alternatively and equivalently, as shown in Figure 20, relative to the outer surface of the jam collar 1 10, in those embodiments in which the outer surface is parallel to the axis A). [0049] It will be noted that the coefficients of friction are therefore shown to be the same, however it is possible that they would be different, depending on such things as the materials of construction of the various components and their surface finishes. The forces Fn and Fn2 are, respectively, the normal forces that are applied at the aforementioned interfaces, which result in the aforementioned frictional forces. The design geometry can be optimized to gain additional torque holding by controlling Fcl, a, MU, r and r2.

[0050] The assembly shown herein relates to an isolator, however it will be understood that the isolator is but an example of a suitable pulley device, and that the assembly may be used with other types of pulley device, such as a fixed pulley or a pulley with decoupling capability in addition to or instead of isolation capability.

[0051] The method steps illustrated in Figures 1 -20 for attaching a pulley device to a drive shaft can also be represented by the flow diagram shown in Figure 21 . The method is shown in Figure 21 at 400. The pulley device (e.g. the isolator 10) includes a pulley and has a shaft adapter that has a bore extending from a first axial end of the shaft adapter to a second axial end of the shaft adapter, wherein the pulley device further includes a shaft adapter shoulder proximate the first axial end, a first shaft adapter connection structure which is threaded and is in the bore, and a second shaft adapter connection structure, the drive shaft including a shaft axial end, a shaft shoulder, a first shaft connection structure which is threaded, and a second shaft connection structure which is threaded and a third shaft connection structure which is at the shaft axial end. In a step 402, the method 400 includes inserting the shaft axial end into the bore and causing relative rotation between the shaft and the shaft adapter in a first rotational direction to engage the first shaft adapter connection structure and the first shaft connection structure with one another to provide a first non-destructively releasable connection. In a step 404, the method 400 includes inserting a jam collar into the bore, wherein the jam collar has a jam collar wedging structure that is generally conical, a jam collar radially outer structure, and a jam collar axial connection structure. In a step 406, the method 400 includes providing a threaded fastener with a fastener wedging structure and a second fastener connection structure. In a step 408, the method 400 includes connecting the second fastener connection structure to the second shaft connection structure to provide a second non-destructively releasable connection, such that the fastener wedging structure engages the jam collar wedging structure to generate a selected first frictional force between the jam collar radially outer structure and the second shaft adapter connection structure, and a selected second frictional force between the jam collar axial connection structure and the third shaft connection structure.

[0052] While various embodiments have been described above, it should be understood that they have been presented only as illustrations and examples of the present disclosure, and not by way of limitation. It will be apparent to persons skilled in the relevant art that various changes in form and detail can be made therein without departing from the spirit and scope of the disclosure. Thus, the breadth and scope of the present disclosure should not be limited by any of the above-described example embodiments, but should be defined only in accordance with the appended claims and their equivalents. It will also be understood that each feature of each embodiment discussed herein, and of each reference cited herein, can be used in combination with the features of any other embodiment. All patents and publications discussed herein are incorporated by reference herein in their entirety.

Claims

CLAIMS:

1 . An assembly, comprising:

a pulley device including a pulley and having a shaft adapter that has a bore extending from a first axial end of the shaft adapter to a second axial end of the shaft adapter, wherein the pulley device further includes a shaft adapter shoulder proximate the first axial end, a first shaft adapter connection structure which is threaded and is in the bore, and a second shaft adapter connection structure;

a drive shaft including a shaft axial end, a shaft shoulder, a first shaft connection structure which is threaded, a second shaft connection structure which is threaded and a third shaft connection structure which is an axial end face of the drive shaft, wherein the first shaft adapter connection structure and the first shaft connection structure are engaged with one another by relative rotation between the first shaft adapter connection structure and the first shaft connection structure in a first rotational direction to provide a first non-destructively releasable connection;

a jam collar having a jam collar wedging structure that is generally conical, a jam collar radially outer structure, and a jam collar axial connection structure; and

a threaded fastener having a threaded fastener wedging structure that is generally conical, and a second fastener connection structure which is threaded and which engages the second shaft connection structure to provide a second non-destructively releasable connection,

wherein the threaded fastener wedging structure engages the jam collar wedging structure to drive frictional engagement between the jam collar radially outer structure and the second shaft adapter connection structure, and to drive frictional engagement between the jam collar axial connection structure and the third shaft connection structure, thereby locking the shaft and the shaft adapter against relative rotation in a second rotational direction.

2. The assembly as claimed in claim 1 , wherein the second fastener connection structure is threaded in an opposite hand to the first shaft adapter connection structure.

3. The assembly as claimed in claim 1 , wherein the first shaft connection structure is provided on an outside surface of the shaft, and wherein the second shaft connection structure is provided on a radially inner surface of the shaft.

4. The assembly as claimed in claim 1 , wherein the first shaft connection structure has a right-hand thread, and the second shaft connection structure has a left-hand thread.

5. The assembly as claimed in claim 1 , wherein the shaft shoulder and the shaft adapter shoulder are engaged through an intermediate bearing member, and wherein a selected compression force is present therebetween.

6. The assembly as claimed in claim 1 , wherein the shaft axial end is configured with a shaft tool receiving structure.

7. The assembly as claimed in claim 6, wherein the shaft adapter includes a shaft adapter tool receiving structure.

8. A method of attaching a pulley device to a drive shaft, wherein the pulley device includes a pulley and has a shaft adapter that has a bore extending from a first axial end of the shaft adapter to a second axial end of the shaft adapter, wherein the pulley device further includes a shaft adapter shoulder proximate the first axial end, a first shaft adapter connection structure which is threaded and is in the bore, and a second shaft adapter connection structure, the drive shaft including a shaft axial end, a shaft shoulder, a first shaft connection structure which is threaded, and a second shaft connection structure which is threaded and a third shaft connection structure which is at the shaft axial end, the method comprising:

d) connecting the second fastener connection structure to the second shaft connection structure to provide a second non-destructively releasable connection, such that the fastener wedging structure engages the jam collar wedging structure to generate a selected first frictional force between the jam collar radially outer structure and the second shaft adapter connection structure, and a selected second frictional force between the jam collar axial connection structure and the third shaft connection structure.

9. The method as claimed in claim 8, wherein one of the first shaft adapter connection structure and the second fastener connection structure is a right-hand thread and the other of the first shaft adapter connection structure and the second fastener connection structure is a left-hand thread.

10. The method as claimed in claim 8, wherein the first shaft adapter connection structure is a right-hand thread and the second fastener connection structure is a left-hand thread.