Separators for ring drives

Abstract

In one aspect, a separator is provided for a shaft in an accessory drive system between an engine and an accessory in a vehicle. The separator includes a pulley, a hub, a coil spring clutch, a vibration damping spring, and a carrier positioned to hold an end of the coil spring clutch and an end of the vibration damping spring. The carrier has a groove for holding the end of the coil spring clutch, and wherein the groove has a groove outlet through which the coil spring clutch exits the groove to coil around the outside of the carrier. The carrier has a bridging portion configured to fail before the end wall fails. This allows the carrier to open radially so that the end wall abuts against the wall of the pulley, thereby reducing stress in the end wall.

Description

[0001] Cross-references to related applications

[0002] This application claims the benefit of U.S. Provisional Application No. 63 / 116,161, filed November 19, 2020, the entire contents of which are incorporated herein by reference. Technical Field

[0003] This disclosure generally relates to the field of separators that allow items operatively connected to annular drive components (e.g., engine crankshafts and input shafts with drive accessories on vehicle engines) to temporarily operate at a speed different from that of the annular drive components, and more specifically to a carrier for a separator that holds both a coiled clutch and a vibration damping spring. Background Technology

[0004] A belt-driven accessory, such as a separator mechanism on an alternator, located on the crankshaft of an engine in a vehicle, is known. This decoupling mechanism, which may be referred to as a separator assembly or a separator, allows the associated accessory to temporarily operate at a speed different from the speed of the belt. As is known, the crankshaft undergoes cycles of acceleration and deceleration associated with the ignition of cylinders in the engine. The separator allows the alternator shaft to rotate at a relatively constant speed, even though the engine crankshaft and therefore the separator pulley will experience these same cycles of deceleration and acceleration, commonly referred to as rotational torsional vibration or torsion.

[0005] A carrier has been used in separators employing coil spring clutches for some time. The carrier holds the ends of the coil spring clutch and also the ends of the damping springs, thus helping to keep the components together. However, it has been found that, over time, after multiple cycles of torque transmission through the separator, failure has occurred in the carrier 30. It would be advantageous to provide a separator with enhanced resistance to failure. Summary of the Invention

[0006] In one aspect, a separator is provided, mounted to a shaft and engaging with an annular drive member in an annular transmission for transmitting power between an engine and at least one accessory in a vehicle. The separator includes a separator input member and a separator output member rotatable relative to the separator input member. One of the separator input member and the separator output member is shaped to engage with the annular drive member. The separator also includes a coiled clutch and a vibration damping spring, and a carrier member positioned to transmit torque in series between the separator input member and the separator output member. The carrier member is positioned to hold an end of the coiled clutch and an end of the vibration damping spring to allow torque transmission between the end of the coiled clutch and the end of the vibration damping spring. The carrier member has a groove for holding the end of the coiled clutch. The groove has a groove outlet through which the coiled clutch exits the groove to coil around the outside of the carrier member. The groove outlet is defined by an end wall of the carrier member on a radially outer portion of the carrier member. During torque transmission between the separator input and output members via the separator, the end of the coiled spring clutch is positioned to apply a clutch-related radial force to the end wall, and a vibration-damping spring is positioned to apply a vibration-damping spring-related force to the carrier member, the vibration-damping spring-related force being at least partially opposite to the clutch-related radial force. The carrier member has a circumference and includes a bridging portion at selected locations around the circumference. This bridging portion has a selected cross-sectional area in the circumferential direction. The selected cross-sectional area is chosen to generate higher stress in the bridging portion than at the end wall during the application of the clutch-related radial force and the vibration-damping spring-related force to the carrier member, so as to cause failure of the bridging portion before end wall failure, thereby allowing the carrier member to open radially under the action of the clutch-related radial force and the vibration-damping spring-related force, so that the end wall abuts radially outward against the wall of one of the separator input and output members. Attached Figure Description

[0007] The foregoing and other aspects of the invention will be better understood by referring to the accompanying drawings, in which:

[0008] Figure 1 This is a front view of an engine with a belt drive and a separator according to an embodiment of the present invention;

[0009] Figure 2 yes Figure 1 The image shows a three-dimensional view of the separator.

[0010] Figure 3A yes Figure 2 An exploded perspective view of the separator is shown in the figure.

[0011] Figure 3B yes Figure 2 Another exploded perspective view of the separator is shown in the figure.

[0012] Figure 4 yes Figure 2 The figure shows a three-dimensional cross-sectional view of the separator.

[0013] Figure 5A Is as Figure 2 The diagram shows a plan view of a portion of the carrier of the separator.

[0014] Figure 5B yes Figure 5A An enlarged view of a portion of the carrier shown in the image.

[0015] Figure 6 yes Figure 1 The diagram shows a three-dimensional cross-sectional view of a portion of the separator.

[0016] Figure 7A This is an enlarged cross-sectional view of a portion of the separator prior to torque transmission, which includes the carrier element of the prior art.

[0017] Figure 7B yes Figure 7A The diagram shows an enlarged cross-sectional view of a portion of the separator during torque transmission.

[0018] Figure 8A yes Figure 2 The diagram shows an enlarged cross-sectional view of a portion of the separator before torque transmission, which includes a carrier element according to this disclosure.

[0019] Figure 8B yes Figure 8A The image shows an enlarged cross-sectional view of a portion of the separator during torque transmission.

[0020] Figure 9 It is shown that in passing through having Figure 7A and Figure 7B The diagram shows a stress curve generated during torque transmission in the separator of a prior art carrier, and an illustration of a prior art carrier.

[0021] Figure 10 It is shown in passing Figure 2 The diagram shows the stress curve generated by the torque transmission of the separator and the illustration of the bearing component. Detailed Implementation

[0022] Reference Figure 1 , Figure 1An engine 10 for a vehicle is shown. The engine 10 includes a crankshaft 12 that drives a ring-shaped transmission element, which may be, for example, a belt 14. The engine 10 drives a plurality of accessories 16 (shown in dashed outlines), such as an alternator 18, via the belt 14. Each accessory 16 includes an input drive shaft 15 having a pulley 13 driven thereon by the belt 14. A separator 20 is provided in place of the pulley between the belt 14 and the input shaft 15 of any one or more of the belt-driven accessories 16, and particularly between the belt 14 and the input shaft 15 of the alternator 18.

[0023] Reference Figure 2 , Figure 3A and Figure 3B These figures show a three-dimensional assembled view and two exploded perspective views of the separator 20. The separator 20 includes a hub 22, a pulley 24, a first bearing component 26, a second bearing component 27, a vibration damping spring 28, a carrier component 30, and a coiled spring clutch 32.

[0024] Hub 22 can be adapted to be mounted to accessory shaft 15 in any suitable manner. Figure 1 For example, hub 22 may have a shaft mounting hole 36 through which it passes for mounting hub 22 to the end of shaft 15 for joint rotation of hub 22 and shaft 15 about axis A (FIG. 3).

[0025] The pulley 24 is rotatably mounted to the hub 22. The pulley 24 has an outer surface 40 configured to engage with the belt 14. The outer surface 40 is shown as having a groove 42. Therefore, the belt 14 can be a multi-V belt. However, it will be understood that the outer surface 40 of the pulley 24 can have any other suitable configuration and the belt 14 does not need to be a multi-V belt. For example, the pulley 24 can have a single groove and the belt 14 can be a single V belt, or the pulley 24 can have a generally flat portion for engaging the flat belt 14. The pulley 24 also includes an inner surface 43, which a spring-loaded clutch 32 can engage to connect the pulley and the hub 22 together. The pulley 24 can be made of any suitable material, such as steel or aluminum, or in some cases, of polymeric materials, such as certain types of nylon, phenolic resin, or other materials.

[0026] A first support member 26 rotatably supports the pulley 24 onto the hub 22 at a first (proximal) axial end of the pulley 24. The first bearing member 26 can be any suitable type of bearing member, such as a ball bearing. In the illustrated embodiment, the first bearing member 26 is partially supported on the hub 22 and partially supported on an optionally provided additional member 22a. In other embodiments, the hub 22 extends through the first bearing member 26.

[0027] The second bearing member 27 is positioned at the second (distal) axial end of the pulley 24 to rotatably support the pulley 24 on the pulley support surface 48 of the hub 22. The second bearing member 27 can be mounted to the pulley 24 and the hub 22 in any suitable manner. In the illustrated embodiment, the second bearing member 27 can be molded around the pulley support surface 48 by an injection molding process, wherein the hub 22 forms part of the mold. The hub 22 may have a coating before insertion into the mold cavity to prevent the bearing member 27 from firmly adhering to the pulley support surface 48 during the molding process, so that the bearing member 27 can rotate about the hub 22 after the hub 22 and bearing member 27 are removed from the molding machine (not shown). It should be noted that other methods can be used to engage the second bearing member 27 and the pulley 24, such as bonding, and / or using mechanically engaging elements (e.g., resilient locking protrusions) to lock the bearing member 27 to the pulley.

[0028] The vibration isolation spring 28 is configured to adjust the oscillation of the speed of the belt 14 relative to the shaft 15. The vibration isolation spring 28 may be a helical torsion spring having a first helical end 50, which is held on a helical support surface and abuts against a radially extending transmission wall 52 on the bearing member 30. Figure 4 The vibration damping spring 28 has a second helical end 53 that engages with a similar drive wall (not shown) on the hub 22. Figure 3B In the illustrated embodiment, the vibration isolation spring 28 has a plurality of coils 58 located between a first end 50 and a second end 53. The coils 58 are preferably spaced apart by a selected amount, and the vibration isolation spring 28 is preferably mounted in the separator 20 under a selected amount of axial compression to ensure that the first helical end 50 and the second helical end 53 of the spring 28 abut against corresponding drive walls on the carrier 30 and the hub 22. An example of a suitable engagement between the vibration isolation spring 28, the hub 22, and the carrier 30 is shown and described in U.S. Patent 7,712,592, the contents of which are incorporated herein by reference. A thrust plate 73 may be provided to receive the axial thrust of the carrier 30 generated by the axial compression of the spring 28.

[0029] The vibration isolation spring 28 can be made of any suitable material, such as suitable spring steel. The vibration isolation spring 28 can have any suitable cross-sectional shape. In the accompanying drawings, the vibration isolation spring 28 is shown with a generally rectangular cross-sectional shape, which provides the vibration isolation spring 28 with relatively high torsional resistance (i.e., spring stiffness) for a given occupied volume. However, suitable spring stiffness can be obtained with other cross-sectional shapes, such as circular or square cross-sectional shapes.

[0030] Alternatively, the vibration isolation spring 28 may be a compression spring. As another alternative, the vibration isolation spring 28 may be one of two or more vibration isolation springs, each of which is a compression spring. This configuration is illustrated in U.S. Patent No. 7,708,661 and U.S. Patent Application Publication No. US2008 / 0312014, PCT Publication No. WO2007 / 074016, PCT Publication No. WO2008 / 022897, PCT Publication No. WO2008 / 067915, and PCT Publication No. WO2008 / 071306, the entire disclosure of all of which is incorporated herein by reference.

[0031] The coil spring clutch 32 has a first end 51 that can engage with the radial wall 55 of the carrier 30 and is securely connected to the carrier 30. The coil spring clutch 32 has a second end 59 that can float freely. The carrier 30 can be made of any suitable material, such as suitable nylon.

[0032] When torque is applied from belt 14 to pulley 24, thereby driving pulley 24 at a speed faster than that of shaft 15, friction between the inner surface 43 of pulley 24 and the coils of spring clutch 32 drives at least one coil of spring clutch 32 about axis A in a first rotational direction relative to the first end 51 of spring clutch 32. The relative movement between one or more coils driven by pulley 24 relative to the first end 51 causes the clutch spring to expand radially, further strengthening the clamping between the coils of spring clutch 32 and the inner surface 43 of pulley 24. Therefore, the first end 59 of spring clutch 32 transmits torque from pulley to carrier 30. Carrier 30 transmits torque to hub 22 via vibration damping spring 28. This causes hub 22 to reach the speed of pulley 24. Thus, when pulley 24 rotates faster than hub 22, spring clutch 32 operatively connects pulley 24 to carrier 30 and thus to hub 22.

[0033] The dust cover 100 can be installed on the pulley to prevent dust and debris from entering the separator 20 during operation.

[0034] The interaction between the carrier 30 and the coiled spring clutch 32 will be described in further detail below. The carrier 30 has a groove 102 for retaining the first end 51 of the coiled spring clutch 32. Figure 5A The slot 102 has a slot outlet 104 through which the coil spring clutch 32 exits from the slot 102 to coil around the outside of the carrier 30 (shown as 106). The slot outlet 104 is defined on the radially outer portion of the carrier 30 by the end wall 108 of the carrier 30. (As in...) Figure 4 , Figure 5A and Figure 6 As can be seen, the end wall 108 is supported only at its base to the rest of the carrier 30.

[0035] During torque transmission between pulley 24 and hub 22 via separator 20, the first end 51 of coiled spring clutch 32 is positioned to apply a clutch-related radial force F1 to end wall 108, and vibration damping spring 28 is positioned to apply a vibration damping spring-related force F2 to carrier 30, which is at least partially opposite to the clutch-related radial force F1. These forces F1 and F2 are distributed forces and are therefore generated by… Figure 5A The multiple arrows in the text represent...

[0036] Figure 7A and Figure 7B This is an enlarged view of the inner surface 43 of the existing bearing 30' and pulley 24. Figure 9 The prior art carrier 30' is shown more clearly in the image. It can be seen that a small gap, indicated by G, exists between the end wall 108' of the prior art carrier 30' and the inner surface 43 of the pulley 24. Due to the gap G in the prior art carrier 30', the radial force F1 associated with the clutch will cause the end wall 108' to flex (bend) radially outward toward the inner surface 43 of the pulley 24, and the first end 51 of the coil spring clutch 32 will, as needed, bend locally at least where the prior art end wall 108' has already flexed. The flexing of the first end 51 and the end wall 108' in... Figure 7B The dashed outline is used to represent the shape. Figure 9 The graph shown illustrates curve 120, which represents the relationship between the highest stress generated in the prior art carrier 30' and the torque transmission through the prior art separator having the prior art carrier 30'. The highest stress is generated at the base of the end wall 108'. As can be seen, at a torque of 60 Nm—a torque that can be transmitted in certain situations, such as during a cold engine start—the maximum stress generated is approximately 209 MPa (see point 122 on curve 120). Repeated torque transmission through the separator having the prior art carrier 30' can ultimately lead to failure of the carrier 30' at the base of the end wall 108' due to fatigue.

[0037] For the load-bearing component 30, such as Figure 5AAs seen in the diagram, the carrier 30 has a circumference and includes a bridging portion 130 at selected locations around the circumference. In the example embodiment shown, the bridging portion 130 is angled at approximately 90 degrees to the net force F1 at an angle Ab, where the net force F1n is the sum of the distributed forces F1. The angle Ab can be located at any angle from 60 degrees to 120 degrees relative to the net force F1n, passing approximately 90 degrees. However, in other embodiments, the bridging portion 130 can be positioned at any reasonable location around the circumference of the carrier 30 to allow the carrier 30 to open radially, thereby allowing the end wall 108 to abut against the inner surface 43 of the pulley 24. The bridging portion 130 is a sacrificial connection in the carrier 30 and is intended in at least some embodiments to break off after installation when a selected torque is transmitted to the separator 20. In some embodiments, the bridging portion 130 remains when the separator 20 is assembled, and therefore a gap G remains between the end wall 108 and the inner surface 43 of the pulley 24. Figure 8A After the bridging portion 130 breaks, a crack 132 exists in the bearing member 30 where the bridging portion 130 is located. Figure 5A Therefore, when torque is transmitted through the separator 20 and a force F1 is applied to the first end 51 of the coiled spring clutch 32—a portion of which resists the end wall 108—the carrier 30 expands relatively freely radially to consume the clearance G until the end wall 108 supports against the inner surface 43 of the pulley 24, as... Figure 8B As shown in the figure. Therefore, the bending force applied to the end wall 108' in the prior art carrier 30' is effectively eliminated, and the end wall 108 is simply compressed between the first end 51 of the coil spring clutch 32 and the inner surface 43 of the pulley 24. Figure 10 Curve 140 shows the relationship between the maximum stress generated in the carrier 30 at the base of the end wall 108 and the torque transmitted through the separator 20 having the carrier 30. As can be seen, at a torque of 60 Nm, the maximum stress generated is approximately 46 MPa (i.e., a reduction of approximately 78% compared to the prior art carrier 30'), as shown at point 142 on curve 140.

[0038] To provide an improvement over prior art carriers 30' by including the bridging portion 130, the bridging portion 130 only needs to be shaped to fail before the base of the end wall 108. For this purpose, the bridging portion 130 has a selected cross-sectional area in the circumferential direction, which is selected to generate higher stress in the bridging portion 130 than at the end wall 108 during the application of the radial force F1 associated with the clutch and the force F2 associated with the vibration damping spring to the carrier 30, thereby causing the bridging portion 130 to fail before the end wall 108 fails. As mentioned above regarding... Figure 8BAs indicated, failure of the bridging portion 130 allows the carrier 30 to open radially under the action of the radial force F1 associated with the clutch and the force F2 associated with the vibration isolation spring, thereby causing the end wall 108 to move radially outward to abut against the wall (i.e., the inner surface 43 of the pulley 24).

[0039] In the illustrated embodiment, the bridging portion 130 is approximately 3.5 mm in the circumferential direction. 2 The total cross-sectional area can have a cross-sectional area of ​​approximately 1 mm in the radial direction and approximately 3.5 mm in the axial direction. Depending on the torque required to prevent failure of the bridging portion 130, other cross-sectional areas of the bridging portion 130 can be used.

[0040] In some embodiments, it may be desirable for the bridging portion 130 to fail at a torque transmission of approximately 35 Nm, which may be sufficiently lower than the torque transmission through the separator 20 during a cold engine start of the engine 10 (this torque may be, for example, approximately 40 Nm). In other embodiments, the bridging portion 130 may have a cross-sectional area selected to cause the bridging portion 130 to fail at different torque transmissions through the separator 20.

[0041] Although pulley 24 and hub 22 are shown, any suitable separator input and output components can be provided. In some embodiments, such as those in which the separator 20 is mounted to crankshaft 12, pulley 24 will constitute the separator output component and hub 22 mounted to crankshaft 12 will constitute the separator input component.

[0042] While the description contained herein constitutes multiple embodiments of the invention, it will be understood that other modifications and variations of the invention are readily apparent without departing from the reasonable meaning of the appended claims.

Claims

1. A separator for mounting to a shaft and engaging with an annular drive member in an annular transmission for transmitting power between a vehicle's engine and at least one accessory, the separator comprising: A separator input member and a separator output member, the separator output member being rotatable relative to the separator input member, wherein one of the separator input member and the separator output member is shaped to engage with the annular transmission member; A coiled spring clutch and a vibration damping spring, the coiled spring clutch and the vibration damping spring being positioned to transmit torque in series between the separator input member and the separator output member; and A support member, positioned to hold the end of the coil spring clutch and the end of the vibration isolation spring, to allow torque transmission between the end of the coil spring clutch and the end of the vibration isolation spring. The carrier has a groove for holding the end of the coiled spring clutch, and the groove has an outlet through which the coiled spring clutch exits the groove to coil around the outside of the carrier, wherein the outlet is defined by an end wall of the carrier on a radially outer portion of the carrier. During torque transmission between the separator input member and the separator output member via the separator, the end of the coiled spring clutch is positioned to apply a clutch-related radial force to the end wall, and the vibration isolation spring is positioned to apply a vibration isolation spring-related force to the load-bearing member, the vibration isolation spring-related force being at least partially opposite to the clutch-related radial force. Furthermore, the carrier has a circumference and includes a bridging portion at a selected location around the circumference, wherein the bridging portion has a selected cross-sectional area in the circumferential direction, wherein the selected cross-sectional area is selected to generate higher stress in the bridging portion than at the end wall during the application of the clutch-related radial force and the vibration isolation spring-related force to the carrier, so as to cause failure of the bridging portion before the end wall fails, thereby allowing the carrier to open radially flexibly under the action of the clutch-related radial force and the vibration isolation spring-related force, so that the end wall abuts radially outward against the wall of one of the separator input member and the separator output member.

2. The separator according to claim 1, wherein, The selected cross-sectional area is chosen such that it causes the bridging section to fail when the torque transmission is less than the torque transmission through the separator during engine startup.

3. The separator according to claim 1, wherein, The selected cross-sectional area was chosen such that it would cause the bridging section to fail when the torque transmission was less than 35 Nm.

4. The separator according to claim 1, wherein, The bridging portion is positioned at approximately 90 degrees to the net force representing the sum of the radial forces associated with the clutch.

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