Decoupler with torque limiting function to protect components

Abstract

In one aspect, a decoupler is provided for mounting on a shaft and engaging an endless drive member in an endless drive arrangement for transmitting power between an engine and an accessory of a vehicle, the decoupler including a decoupler input member and a decoupler output member. The wrap spring clutch and the separation spring are arranged to transfer torque in series between the decoupler input member and the decoupler output member. The carrier is arranged to hold an end of the wrap spring clutch and an end of the separation spring to enable torque transfer therebetween. The wrap spring clutch is arranged to transfer torque between the separation spring and one of the decoupler input member and the decoupler output member. The carrier is supported on a support surface fixed to one of the decoupler input member and the decoupler output member.

Description

[Technical field]

[0001] (Related Applications) This application claims the benefit of U.S. Provisional Application No. 63 / 313,737, filed February 25, 2022, U.S. Provisional Application No. 63 / 325,580, filed March 30, 2022, and U.S. Provisional Application No. 63 / 363245, filed April 20, 2022, the entire disclosures of which are incorporated herein by reference.

[0002] (Technical field) The present disclosure relates generally to the field of decouplers that allow elements operably connected to an endless drive member (such as the crankshaft of an engine and the input shaft of a belt-driven accessory of a vehicle engine) to temporarily operate at speeds other than the speed of the endless drive member, and more particularly to support member features in a decoupler for supporting a carrier that holds both ends of a wrap spring clutch and a separation spring. [Background technology]

[0003] It is known to provide a decoupler mechanism for an accessory, such as an alternator, that is driven by a belt from the crankshaft of a vehicle engine. Such a decoupling mechanism, sometimes referred to as a decoupler assembly or decoupler, allows the associated accessory to temporarily operate at a speed different from that of the belt. As is well known, the crankshaft undergoes cycles of acceleration and deceleration associated with the combustion of the cylinders of the engine. The decoupler allows the alternator shaft to rotate at a relatively constant speed even as the crankshaft from the engine, and hence the decoupler pulley, undergoes these cycles of deceleration and acceleration, commonly referred to as rotational torsional vibration.

[0004] Carriers have been used in the past in decouplers, where a wrap spring clutch is used. The carrier holds the end of the wrap spring clutch and the end of the separation spring, helping to hold the assembly together. However, decouplers, especially those used in vehicles that idle for long periods of time, such as taxis, police cars, and emergency vehicles, have been found to experience premature wear on the carrier. Such wear can contaminate the grease present in the decoupler, ultimately reducing the operating life of the grease and therefore the operating life of the decoupler. Summary of the Invention [Problem to be solved by the invention]

[0005] It would be advantageous to provide a decoupler that exhibits a reduced amount of wear. [Means for solving the problem]

[0006] In one aspect, a decoupler is provided for mounting on a shaft and engaging an endless drive member in an endless drive arrangement for transferring power between an engine and an accessory of a vehicle. The decoupler includes a decoupler input member and a decoupler output member rotatable relative to the decoupler input member. Either the decoupler input member or the decoupler output member is configured to engage the endless drive member. The decoupler further includes a wrap spring clutch and a separation spring arranged to transfer torque in series between the decoupler input member and the decoupler output member. The decoupler further includes a carrier arranged to hold an end of the wrap spring clutch and an end of the separation spring to enable torque transfer between an end of the wrap spring clutch and an end of the separation spring. The wrap spring clutch is arranged to transfer torque between the separation spring and one of the decoupler input member and the decoupler output member. The carrier is supported on a support surface fixed to one of the decoupler input member and the decoupler output member.

[0007] In another aspect, a decoupler is provided for mounting on a shaft and engaging an endless drive member in an endless drive arrangement for transferring power between an engine and at least one accessory of a vehicle. The decoupler includes a decoupler input member and a decoupler output member rotatable relative to the decoupler input member. Either the decoupler input member or the decoupler output member is configured to engage the endless drive member. The decoupler includes a wrap spring clutch and a separation spring arranged to transfer torque in series between the decoupler input member and the decoupler output member. The decoupler includes a carrier arranged to hold an end of the wrap spring clutch and an end of the separation spring to enable torque transfer between an end of the wrap spring clutch and an end of the separation spring. The wrap spring clutch is arranged to transfer torque between the separation spring and one of the decoupler input member and the decoupler output member, and the separation spring is arranged to transfer torque between the wrap spring clutch and the other of the decoupler input member and the decoupler output member. The other of the decoupler input member and the decoupler output member has a carrier retainer slot extending circumferentially thereon, an entry slot extending at least partially axially at a first end of the carrier retainer slot, and an anti-ramp drive feature at a second end of the carrier retainer slot, the carrier includes a radially inward protrusion having an anti-ramp drive receiving surface thereon, the carrier is mountable to the other of the decoupler input member and the decoupler output member such that the radially inward protrusion is insertable along the entry slot to reach the carrier retainer slot, the carrier is moveable along the carrier retainer slot, and when the decoupler output member overruns the decoupler input member, the anti-ramp drive feature engages the anti-ramp drive receiving surface to drive the carrier to rotate with the other of the decoupler input member and the decoupler output member.

[0008] These and other aspects of the present invention will be better understood with reference to the following accompanying drawings, in which: [Brief description of the drawings]

[0009] [Figure 1] FIG. 1 is an elevational view of an engine with a belt drive with a decoupler according to one embodiment of the present disclosure. [Diagram 2] FIG. 2 is a perspective view of the decoupler shown in FIG. [Figure 3A] FIG. 3 is an exploded perspective view of the decoupler shown in FIG. 2. [Figure 3B] FIG. 3 is another exploded perspective view of the decoupler shown in FIG. 2. [Figure 4] FIG. 3 is a cross-sectional view of the decoupler shown in FIG. [Figure 5A] FIG. 1 is a cross-sectional elevation view of a prior art decoupler in drive mode. [Figure 5B] FIG. 2 is a cross-sectional elevation view of a decoupler in drive mode. [Figure 6A] FIG. 5B is a cross-sectional elevation view of the decoupler shown in FIG. 5A in overrun mode. [Figure 6B] FIG. 3 is a cross-sectional elevation view of the decoupler shown in FIG. 2 in overrun mode. [Figure 7A] FIG. 5B is a perspective view of a carrier from the decoupler shown in FIG. 5A. [Figure 7B] FIG. 5B is another perspective view of the carrier from the decoupler shown in FIG. 5A. [Figure 7C] FIG. 3 is a perspective view of a carrier from the decoupler shown in FIG. 2. [Figure 7D] FIG. 3 is another perspective view of the carrier from the decoupler shown in FIG. 2. [Figure 8A] FIG. 5B is a perspective view of a thrust member from the decoupler shown in FIG. 5A. [Figure 8B] FIG. 3 is a perspective view of a tab support member from the decoupler shown in FIG. 2. [Figure 9A] 8B and the carrier shown in FIG. 7D in an engine-off position. FIG. [Figure 9B]8B and the carrier shown in FIG. 7D in a perspective view in a position when the engine is operating and a selected average torque is being transferred through the decoupler shown in FIG. 2. [Figure 9C] FIG. 8C is a perspective view of the tab support member shown in FIG. 8B and the carrier shown in FIG. 7D in position when the decoupler is in overrun mode. [Figure 10A] 3 is an exploded perspective view of an embodiment of the decoupler of FIG. 2, in which the hub includes circumferentially extending retainer slots. [Figure 10B] 3 is another exploded perspective view of the embodiment of the decoupler of FIG. 2, in which the hub includes circumferentially extending retainer slots. [Figure 11A] FIG. 10B is a top perspective view of a carrier from the decoupler shown in FIG. 10A. [Figure 11B] FIG. 10B is another perspective view of the carrier from the decoupler shown in FIG. 10A. [Figure 12A] FIG. 10B is a perspective view of the carrier and hub assembly of FIG. 10A, with the carrier in a first rotational position about the hub. [Figure 12B] FIG. 10B is a perspective view of the carrier and hub assembly of FIG. 10A, with the carrier in a second rotational position about the hub. [Figure 12C] FIG. 10B is a perspective view of the carrier and hub assembly of FIG. 10A, with the carrier in a third rotational position about the hub. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] For simplicity and clarity of description, reference numerals may be repeated among the figures where appropriate to indicate corresponding or similar elements. In addition, a number of specific details are described to enable a thorough understanding of one or more embodiments described herein. However, one skilled in the art can appreciate that the embodiments described herein can be practiced without these specific details. In some cases, well-known methods, procedures, and components have not been described in detail so as not to obscure the embodiments described herein. Although exemplary embodiments are shown and described below, it should be understood at the outset that the principles of the present disclosure can be implemented using many techniques, whether currently known or not. The present disclosure is not limited to the exemplary embodiments and techniques shown and described below.

[0011] Various terms used throughout this specification may be read and understood as follows, unless the context indicates otherwise: "or" as used throughout is inclusive as written "and / or". Singular articles and pronouns used throughout include their plurals and vice versa. Similarly, gender pronouns include the corresponding pronouns, so pronouns should not be understood as limiting what is described herein to use, implementation, performance, etc., by a single gender. "Exemplary" should be understood as "example" or "illustration," and not necessarily as "preferred" over other embodiments. Further definitions of terms may be set forth herein, which may apply to prior and subsequent instances of those terms, as will be understood upon reading this specification. It should also be noted that the use of the terms "a" or "an" is understood to represent "at least one" in all instances, unless expressly stated otherwise or clearly understood to mean "one."

[0012] Modifications, additions, or omissions may be made to the systems, devices, and methods described herein without departing from the scope of the disclosure. For example, system and device components may be integrated or separated. Further, operations of the systems and devices disclosed herein may be performed by more, fewer, or other components, and methods described may include more, fewer, or other steps. In addition, steps may be performed in any suitable order. As used herein, "each" refers to each element of a set or each element of a subset of a set.

[0013] The embodiments of the invention described herein are illustrative (e.g., with respect to details of materials, shapes, dimensions, and construction) and are not intended to be limiting of the claims appended hereto and any modifications made thereto. Those skilled in the art will recognize that many further alternative embodiments and modifications are possible, and that the following examples are merely illustrative of one or more embodiments. Thus, the scope of the invention is limited only by the claims appended hereto and any modifications made thereto.

[0014] Please refer to Figure 1, which shows an engine 10 for a vehicle. The engine 10 includes a crankshaft 12 that drives an endless drive element, which may be, for example, a belt 14. Through the belt 14, the engine 10 drives a number of accessories 16, such as an alternator (designated 16a). Each accessory 16 includes an input shaft 15 with a pulley 13 thereon that is driven by the belt 14. Instead of a pulley, a decoupler 20 is provided between the belt 14 and any one or more of the input shafts 15 of the belt-driven accessories 16, in particular the alternator 16a.

[0015] 2, 3A, 3B, and 4, which respectively show a perspective view, two exploded perspective views, and a cross-sectional view of decoupler 20. Decoupler 20 includes a hub 22, a pulley 24, a first bearing member 26, a second bearing member 27, a separation spring 28, a carrier 30, and a wrap spring clutch 32.

[0016] Hub 22 may be adapted for attachment to accessory shaft 15 (FIGS. 1 and 3B) in any suitable manner. For example, hub 22 may have a shaft mounting opening 36 therethrough that is used to mount hub 22 to the end of shaft 15 for co-rotation of hub 22 and shaft 15 about axis A (FIG. 3B).

[0017] Pulley 24 is rotatably mounted on hub 22. Pulley 24 has an outer surface 40 configured to engage belt 14. Outer surface 40 is shown having grooves 42. Thus, belt 14 may be a multi-V belt. However, it should be understood that outer surface 40 of pulley 24 may have other suitable configurations and belt 14 need not be a multi-V belt. For example, pulley 24 may have a single groove and belt 14 may be a single V belt, or pulley 24 may have a generally flat portion for engaging flat belt 14. Pulley 24 further includes an inner surface 43 that is engaged by wrap spring clutch 32 to couple pulley 24 and hub 22 together. Pulley 24 may be made of any suitable material, such as steel, aluminum, or in some cases, may be made of polymeric materials, such as certain nylons, phenolics, etc. As can be seen in FIG. 3A, pulley 24 has a proximal end 46 (i.e., the end closer to the accessory to which pulley 24 is attached) and a distal end 47 (i.e., the end farther from the accessory to which pulley 24 is attached).

[0018] The first bearing member 26 rotatably supports the pulley 24 on the hub 22 at a proximal axial end 46 of the pulley 24. The first bearing member 26 may be any suitable type of bearing member, such as a ball bearing. The bearing member 26 may be constrained on the hub 22 by a press-fit bearing retainer 22a.

[0019] The second bearing member 27 is disposed at a distal end 47 of the pulley 24 to rotatably support the pulley 24 on the hub 22. The second bearing member 27 may be attached to the pulley 24 and the hub 22 in any suitable manner. In the illustrated embodiment, the second bearing member 27 is a separate polymeric element that is captured in a groove 48 on the hub 22.

[0020] The isolation spring 28 is provided to accommodate oscillations in the speed of the belt 14 relative to the shaft 15. The isolation spring 28 may be a helical torsion spring having a first helical end 50 (FIG. 3B) carried by a helical support surface 55 and abutting a radially extending driver wall 52 (FIG. 3A) on the carrier 30. The isolation spring 28 has a second helical end 53 (FIG. 3A) that engages a similar drive wall 57 (part of which is visible in FIG. 3B) on the hub 22. In the illustrated embodiment, the isolation spring 28 has a plurality of coils 58 between the first end 50 and the second end 53. The coils 58 are preferably spaced apart by a selected amount and the isolation spring 28 is preferably under a selected amount of axial compression induced in the decoupler 20 such that the isolation spring 28 is biased to maintain the first and second helical ends 50 and 53 in general abutment with the respective drive walls 52 and 57 on the carrier 30 and hub 22. Examples of suitable engagements between the isolation spring 28, hub 22 and carrier 30 are shown and described in U.S. Patent No. 7,712,592, the disclosure of which is incorporated herein by reference.

[0021] The wrap spring clutch 32 and the separation spring 28 are arranged to transfer torque in series between the decoupler input member (in this embodiment, the pulley 24) and the decoupler output member (in this embodiment, the hub 22). In this embodiment, the separation spring 28 is arranged to receive torque from the wrap spring clutch 32 and transfer the torque at least indirectly to the hub 22. In other words, in this embodiment, the pulley 24 transfers torque from the belt 14 (FIG. 1) to the wrap spring clutch 32. The wrap spring clutch 32 transfers torque from the pulley 24 to the separation spring 28. The separation spring 28 transfers torque from the wrap spring clutch 32 to the hub 22. It should be noted that in alternative embodiments, the decoupler input member could be the hub 22 and the decoupler output member could be the pulley 24. In such an embodiment, the decoupler may be structurally identical to the decoupler 20 shown in FIGS. 2-4, except that torque is first applied to the hub 22 (through the shaft 15 of the accessory 16) and transferred from the hub 22, in turn, to the separation spring 28, the wrap spring clutch 32, and the pulley 24. In another embodiment that is structurally different from that shown in FIGS. 2-4, the wrap spring clutch 32 may be located radially inward of the separation spring 28 instead of radially outward of the separation spring 28. In this alternative embodiment, the pulley 24 serves as the decoupler input member, and torque may be transferred from the belt 14 (FIG. 1) to the separation spring 28, from the separation spring 28 to the wrap spring clutch 32, and from the wrap spring clutch 32 to the hub 22. In yet another embodiment in which the wrap spring clutch 32 is radially inward of the separation spring 28, the hub 22 serves as a decoupler input member and may transfer torque from the belt 14 (FIG. 1) to the wrap spring clutch 32, from the wrap spring clutch 32 to the separation spring 28, and from the separation spring to the hub 22.

[0022] The isolation spring 28 may be made from any suitable material, such as a suitable spring steel. The isolation spring 28 may have any suitable cross-sectional shape. In the figures, the isolation spring 28 is shown as having a generally rounded rectangular cross-sectional shape, which provides a relatively high torsional resistance (i.e., spring constant) for a given occupied volume. However, suitable spring constants may be obtained with other cross-sectional shapes, such as circular or square cross-sectional shapes.

[0023] The wrap spring clutch 32 is generally helical and has a first end 51 (FIG. 3B) that is engageable with the first helical end 50 of the separation spring 28 for torque transmission. The first end 51 of the wrap spring clutch 32 may be fixedly coupled to the carrier 30 by having one or more curved portions (e.g., shown as 51a) that securely engage with a carrier slot 80 (FIG. 3A) of the carrier 30, which are complementary to the first end 51 of the wrap spring clutch 32. The curved shape of the first end 51 and its engagement with the carrier slot 80 prevents disengagement of the first end 51 from the carrier slot 80. The wrap spring clutch 32 also has a second end 59 that is free to move. The wrap spring clutch 32 may be made from any suitable material, such as a suitable type of steel. The carrier 30 itself may be made from any suitable material, such as a suitable nylon.

[0024] In the embodiment shown in FIGS. 2-4, when torque is applied from belt 14 to pulley 24, driving pulley 24 at a speed greater than the speed of shaft 15 (i.e., greater than hub 22), friction between inner surface 43 of pulley 24 and the coils of wrap spring clutch 32 drives at least one of the coils of wrap spring clutch 32 in a first rotational direction about axis A at least a predetermined angle relative to first end 51 of wrap spring clutch 32. The relative movement between the one or more coils driven by pulley 24 relative to first end 51 causes the clutch springs to expand radially, which further enhances the grip between the coils of wrap spring clutch 32 and inner surface 43 of pulley 24. As a result, first end 51 of wrap spring clutch 32 transfers torque from pulley 24 to hub 22 via isolation spring 28. As a result, hub 22 is pulled up to the rotational speed of pulley 24. Thus, when pulley 24 rotates faster than hub 22 , the wrap spring clutch 32 operatively connects pulley 24 to carrier 30 and therefore to hub 22 , which may be referred to as the drive mode of decoupler 20 .

[0025] When the engine 10 (FIG. 1) stops running, the belt 14 also stops moving. Depending on the rotational inertia present in the rotating elements of which the shaft 15 forms a part, significant rotational torque may be exerted by the shaft 15 and the hub 22 may continue to rotate. When this occurs, the wrap spring clutch 32 is driven to rotate in a manner that tends to reduce its diameter, thereby reducing its engagement with the pulley 24. The wrap spring clutch 32 thus releases its grip on the pulley 24, so that the hub 22 is permitted to rotate even though the pulley 24 has stopped rotating. This is referred to as the overrun mode of the decoupler 20. In the overrun mode, the hub 22 rotates for a short period of time until friction causes the rotating elements and the shaft 15 and hub 22 to slow down to a stop.

[0026] It should be noted that the separation spring 28 changes size radially based on the amount of torque transmitted therethrough. In the illustrated embodiment, the separation spring 28 expands radially as the torque transmitted therethrough increases. A sleeve 66 may be optionally provided to ensure separation of the separation spring 28 and the wrap spring clutch 32 during radial expansion of the separation spring 28. The sleeve 66 may function as an expansion limiter for the separation spring 28 by occupying a portion of the radial space between the separation spring 28 and the wrap spring clutches 3 and 2. If the torque transmitted through the separation spring 28 is higher than a selected value, the radial expansion of the separation spring 28 will cause the separation spring 28 to bring the sleeve 66 into solid contact with the wrap spring clutch 32, at which point the separation spring 28 is physically restrained from further radial expansion. At this point, torque transmission is effected in part by engagement of the sleeve 66 with the radially inner surface of the wrap spring clutch 32, and consequently by engagement of the sleeve 66 with the outer surface of the coil 58 of the separation spring 28. In some embodiments, the sleeve 66 protects the isolation spring 28 in the event of a torque transmission event outside of the desired range of torque transmission through the decoupler 20. In other words, in some embodiments, the isolation spring 28 is not expected to transmit torque through the sleeve 66 during normal operation.

[0027] It should be appreciated that during operation of the decoupler 20, the wrap spring clutch 32 is arranged to transfer torque between the separation spring 28 and one of the decoupler input and output members. The carrier 30 is supported on a support surface 100 fixed to one of the decoupler input and output members. For example, in this embodiment, the decoupler input member is the pulley 24. Thus, in this embodiment, the support surface 100 is fixed to the pulley 24. The support surface 100 can be provided on an inner projection 102 formed directly from the material of the pulley 24 itself. Alternatively, the support surface 100 can be fixed to the pulley 24, but the support surface 100 can be provided on an inner member (not shown) separate from the pulley, but fixedly connected (e.g., by press fit) to rotate with the pulley 24.

[0028] 5A and 5B, and 6A and 6B, show the operation of the decoupler 20 in two modes compared to the prior art decoupler 200. In FIG. 5A, the decoupler 200 is shown in a drive mode, while in FIG. 5B, the decoupler 20 is shown in a drive mode. In FIG. 6A, the decoupler 200 is shown in an overrun mode, while in FIG. 6B, the decoupler 20 is shown in an overrun mode. The decoupler 200 may be similar in some respects to the decoupler 20, and includes a hub 222, a pulley 224, a separation spring 228, a carrier 230, a wrap spring clutch 232, a first bearing member 226, and a second bearing member 227, which may be similar to the hub 22, the pulley 24, the separation spring 28, the carrier 30, the wrap spring clutch 32, the first bearing member 26, and the second bearing member 27, respectively. Some differences are described below.

[0029] The decoupler 200 has a bearing surface 300 that is fixed relative to the hub 222. In FIG. 5A, the bearing surface 300 is shown on a thrust member 302 that is fixedly attached (e.g., by a press fit) to the hub 222. During operation of the decoupler 200 in the drive mode, torque is transferred from a belt (not shown, but which may be similar to the belt 14) to the pulley 224. The torque is transferred from the pulley 224 to the isolation spring 228 by the wrap spring clutch 232, and from there to the hub 222. During any decoupler operation, torsional vibrations are generated between the pulley 224 and the hub 222. These torsional vibrations are the result of the operation of the engine driving the crankshaft that drives the belt. The isolation spring 228 deflects to a greater or lesser extent during such torsional vibrations, resulting in relative movement between the pulley 224 and the hub 222. When the decoupler 200 is operating in a drive mode, the wrap spring clutch 232 is fixedly engaged with the pulley 224, and therefore the carrier 230 is likewise rotatably fixed to the pulley 224. As described above, due to the deflection of the isolation spring 228 during torsional vibration, the hub 222 is not rotationally fixed to the pulley 224. As a result, during torsional vibration, relative motion occurs between the carrier 230 and the hub 222, and therefore between the carrier 230 and the support surface 300, leading to repetitive oscillatory sliding motion between the carrier 230 and the support surface 300. The repetitive oscillatory sliding between the carrier 230 and the support surface 300 can cause wear on the carrier 230, thereby causing contamination and breakdown of any grease that may be present in the decoupler 200. This is especially true for vehicles that spend a significant amount of time idling, such as taxis, police vehicles, and emergency vehicles.

[0030] In contrast, decoupler 20 (FIG. 5B) has a carrier 30 supported on a support surface 100 fixed to pulley 24. As with decoupler 200, during operation of decoupler 20 in a drive mode, wrap spring clutch 32 is fixedly engaged with pulley 24, so that carrier 30 is also rotationally fixed to pulley 24, and hub 22 is not rotationally fixed to pulley 24 due to deflection of isolation spring 28 during torsional vibration. Because support surface 100 is fixed to pulley 24, there is no relative movement between carrier 30 and support surface 100. As a result, there is no repetitive oscillatory sliding motion to cause wear on carrier 30 as in decoupler 200. This is particularly advantageous for vehicles that spend a significant amount of time idling, such as taxis, police vehicles, and emergency vehicles, as discussed above.

[0031] 6A and 6B show the decoupler 200 and the decoupler 20, respectively, in overrun mode. When the decoupler 200 is in its overrun mode, the pulley 224 stops rotating and the hub 222 continues to rotate. Because there is some frictional engagement between the wrap spring clutch 232 and the pulley 224, when in overrun mode, the carrier 230 resists continuing to rotate with the hub 222. However, if the carrier 230 rotationally lags behind the hub 222, there is a risk that one end or the other of the separation spring 228 will fall out of engagement with the drive wall on the hub 222 or the drive wall on the carrier 230. The next time the engine 10 is started, the pulley 224 will drive the wrap spring clutch 232 to engage the carrier 230 with the second end of the separation spring 228, which will engage the first end of the separation spring 228 with the hub 222, which is undesirable. Depending on the speed of the impact, the forces on the components can be significant. To prevent this, the carrier 230 is rotatably coupled to the hub 222 by an element called an "anti-ramp" feature 350, shown in FIG. 8A, which engages with an anti-ramp engagement feature 352 on the carrier 230, shown in FIG. 7A. The anti-ramp drive feature 350 in the illustrated embodiment is provided on the thrust member 302. The anti-ramp drive feature 350 limits, in an overrun mode, just how far the hub 222 can rotate relative to the carrier 230. Once the small degree is exhausted, the anti-ramp drive feature 350 engages with the anti-ramp engagement feature 352 on the carrier 230, thereby driving the carrier 230 together with the hub 222, thereby preventing the end of the separation spring 228 from moving too far away from the aforementioned drive wall on the hub 222 and carrier 230. Thus, the carrier 230 is said to be rotatably coupled to the hub 222 (in the overrun mode).

[0032] Because the anti-ramp drive feature 350 rotatably couples the carrier 230 to the hub 222 during an overrun event (i.e., during overrun mode), there is no relative movement between the carrier 230 and the support surface 300. Thus, there is no wear on the carrier 230 in overrun mode.

[0033] 6B, an anti-ramp drive feature may be provided to keep the carrier 30 rotatably coupled to the hub 22 and prevent the first and second ends 50, 53 of the isolation spring 28 from moving too far away from the drive walls 57, 52 on the hub 22 and the carrier 30, respectively, as will be further described below. Because the carrier 30 is rotatably coupled to the hub in overrun mode and the support surface 100 is rotatably coupled to the pulley 24, there is some sliding movement between the carrier 30 and the support surface 100 when the decoupler 20 is in overrun mode. However, whereas the decoupler 20 only operates briefly in overrun mode, the decoupler 20 may operate for a much longer period in drive mode (especially while the engine is idling, where relatively large torsional vibrations may occur). Thus, carrier 30 experiences less wear from sliding on support surface 100 of decoupler 20 compared to carrier 230 sliding on support surface 300 of decoupler 200 .

[0034] To be clear, the term "rotatably coupled" does not limitingly mean that one component is fixedly coupled to another. There may be a small amount of lost motion between the two such that one component may rotate alone for a short period of time until engaged and then drive the other component to rotate.

[0035] An example of the above-mentioned anti-ramp drive feature for the decoupler 20 will be described with reference to Figures 7B and 8B. The anti-ramp drive feature is indicated at 150 and is fixed to the decoupler output member (i.e., the hub 22 as seen in Figure 4). In other words, it should be noted that the wrap spring clutch 32 transmits torque between the separation spring 28 and one of the decoupler input member and the decoupler output member. It can be said that the anti-ramp drive feature 150 is fixed to the other of the decoupler input member and the decoupler output member. In this embodiment, the wrap spring clutch 150 transmits torque between the decoupler input member (pulley 24) and the separation spring 28, and therefore the anti-ramp drive feature 150 is fixed to the decoupler output member (hub 22).

[0036] The anti-ramp drive feature 150 may be provided as a tab 152 on a tab support member 154 that is fixedly attached (e.g., by press fit) to the hub 22. The tab 152 may span a circumferential gap 156 in the carrier 30. The anti-ramp drive feature 150 is positioned to engage an anti-ramp drive receiving surface 158 at one end of the circumferential gap 156 to urge the carrier 30 to rotate with the hub 22 when the hub 22 overruns the pulley 24 (i.e., to urge the carrier 30 to rotate with the decoupler output member when the decoupler output member overruns the decoupler input member).

[0037] The tab support member 154 may be made from any suitable material, such as a suitable metal, such as steel or a type of aluminum.

[0038] 9A-9C show several positions of the anti-ramp drive feature 150 and the anti-ramp drive bearing surface 158 on the carrier 30. For example, the position shown in FIG. 9A is the position of the anti-ramp drive feature 150 and the anti-ramp drive bearing surface 158 when the engine 10 (FIG. 1) is stopped. Thus, no torque is being transferred through the decoupler 20 at that time. It can be seen that the anti-ramp drive feature 150 and the anti-ramp drive bearing surface 158 are very close to each other. In some embodiments, they may be spaced less than 5 degrees apart from each other.

[0039] 9B is the position at which the engine 10 is operating and at an average amount of torque transfer. As can be seen, the anti-ramp drive feature 150 and the anti-ramp drive bearing surface 158 are spaced farther apart than they are when the engine 10 is stopped. Thus, it should be appreciated that as the torque transferred through the decoupler 20 increases, the anti-ramp drive feature 150 and the anti-ramp drive bearing surface 158 move farther apart from each other.

[0040] 9C illustrates the anti-ramp drive feature 150 and the anti-ramp drive receiving surface 158 when the decoupler 20 is in overrun mode. As can be seen, the anti-ramp drive feature 150 engages the anti-ramp drive receiving surface 158 to drive the carrier 30 into rotation with the hub 22.

[0041] Please refer to Figures 10A and 10B, which show an alternative embodiment of a decoupler 20. In this embodiment of the decoupler 20, many of the components are the same as their counterparts in Figures 3A and 3B. Some differences are described below.

[0042] The decoupler 20 of FIG. 10A includes a hub 422 instead of the hub 22 and a carrier 430 instead of the carrier 30. The carrier 430 is shown in more detail in FIGS. 11A and 11B. The hub 422 is shown in more detail in FIGS. 12A, 12B, and 12C. The hub 422 includes a carrier retainer slot 500 extending circumferentially therethrough. The hub 422 has an entry slot 502 at a first end of the carrier retainer slot 500 and an anti-ramp drive feature 504 at a second end of the carrier retainer slot 500 (which may be an end wall of the carrier retainer slot 500 at the second end of the carrier retainer slot 500). The entry slot 502 extends axially directly to an end 505 of the hub 422 in the illustrated embodiment (best seen in FIG. 12A), although the entry slot 502 may extend at an angle to form a helical groove. Thus, the entry slot 502 can be said to extend at least partially axially from the first end of the carrier retainer slot 500. The carrier 430 of Figures 11A and 11B can be similar to the carrier 30, except that the carrier 430 includes an anti-ramp drive receiving surface 506 that is a side of a radially inward protrusion 508 that extends radially inward from an annular body, indicated at 510, of the carrier 430.

[0043] To attach the carrier 430 to the hub 422, the user aligns the radially inward projections 508 with the entry slots 502 of the carrier retainer slots 500 (FIG. 12A) and slides the carrier 430 along the entry slots 502 onto the hub 422 until the anti-ramp drive receiving surfaces 506 reach the carrier retainer slots 500. The carrier 430 is then slid circumferentially along the carrier retainer slots 500 until it is in position between the entry slots 502 and the anti-ramp drive features 504. FIG. 12B shows the carrier 430 rotated slightly along the carrier retainer slots 500. FIG. 12C shows the carrier 430 rotated further along the carrier retainer slots 500. In FIGS. 12A, 12B, and 12C, the carrier 430 is shown partially cut away to better show its interaction with the carrier retainer slots 500.

[0044] During normal operation of decoupler 20, when in drive mode, carrier 430 will remain proximate to the second end of carrier retainer slot 500 but will be spaced slightly from anti-ramp drive feature 504. When in overrun mode, hub 422 rotates and anti-ramp drive feature 504 engages anti-ramp drive receiving surface 506 on carrier 430, thereby urging carrier 430 to rotate with hub 422 in a manner similar to carrier 30 and hub 22.

[0045] In the embodiment shown in Figures 10A and 10B, the hub 422 is the decoupler output member and the pulley 24 is the decoupler input member. The wrap spring clutch 32 is arranged to transmit torque between the separation spring 28 and one of the decoupler input member and the decoupler output member (pulley 24 in this example, which is the decoupler input member in this embodiment), so in this embodiment, the anti-ramp drive receiving surface 506 is said to be fixed to the other of the decoupler input member and the decoupler output member. In this embodiment, the wrap spring clutch 32 is arranged to transmit torque between the decoupler input member (pulley 24) and the separation spring 28, and the separation spring 28 is arranged to transmit torque between the wrap spring clutch 32 and the decoupler output member (hub 422). Therefore, the anti-ramp drive feature 500 can be said to be fixed to the decoupler output member (hub 422).

[0046] In general, wrap spring clutch 32 is arranged to transfer torque between isolation spring 28 and one of the decoupler input and output members (in this example, the decoupler input member is pulley 24), and isolation spring 28 is arranged to transfer torque between wrap spring clutch 32 and the other of the decoupler input and output members (in this example, the decoupler output member is hub 422). The other of the decoupler input and output members has a carrier retainer slot 500 extending circumferentially thereon, an entry slot 502 extending at least partially axially at a first end of carrier retainer slot 500, and an anti-ramp drive feature 504 at a second end of carrier retainer slot 500.

[0047] Carrier 430 can be said to include a radially inward protrusion 508 with an anti-ramp drive receiving surface 506 thereon, and is mountable to the other of the decoupler input member and the decoupler output member such that radially inward protrusion 508 is insertable along entrance slot 502 to reach carrier retainer slot 500 and further movable along carrier retainer slot 500 such that when the decoupler output member overruns the decoupler input member, anti-ramp drive feature 504 engages anti-ramp drive receiving surface 506 and drives carrier 430 to rotate with the other of the decoupler input member and the decoupler output member.

[0048] In this embodiment, the anti-ramp drive receiving surface 506 is formed directly on the decoupler output member (i.e., hub 422) rather than on a separate element that is fixedly attached to the decoupler output member, as is the case in the embodiment of Figure 4. This reduces the complexity and cost of the decoupler 20 of Figures 10A and 10B as compared to the embodiment shown in Figure 4.

[0049] In the illustrated embodiment, the carrier 430 includes a bridge 514 that can be broken to form a split. The bridge 514 and split can be as described in WO 2022 / 104478, the entire disclosure of which is incorporated herein. Although not shown, the carrier 30 can include a bridge such as the bridge 514 described in WO 2022 / 104478, supra.

[0050] A cover 84 may be provided which is attachable to the pulleys to prevent dirt and debris from migrating into the decoupler 20 during operation.

[0051] Pulley 24 and hub 22 are merely examples of suitable decoupler input and output members, and any suitable decoupler input and output members may be provided. In some embodiments, such as those in which decoupler 20 is attached to crankshaft 12, pulley 24 would comprise the decoupler output member, and hub 22, which is attached to crankshaft 12, would comprise the decoupler input member.

[0052] The wrap spring clutch 32 is merely one example of a one-way clutch that may be used in the decoupler 20. Alternatively, other suitable types of one-way clutches, such as roller clutches or sprag clutches, may be used, which may transmit torque to the separation springs with or without the presence of a carrier, such as the carrier 30. While the carrier 30 in this embodiment benefits from the presence of radial protrusions, alternatively, a decoupler without the carrier 30 may benefit, as a one-way clutch having a smaller maximum strength may be selected, thereby reducing the torque transmission through the one-way clutch itself.

[0053] In this embodiment, the radial projection projects inwardly from pulley 24 (i.e., from the decoupler input member) and engages a radially outer surface of isolation spring 28. In addition, isolation spring 28 is configured to expand radially as torque transmission therethrough increases. However, it is alternatively possible to provide an embodiment in which the isolation spring contracts radially as torque transmission therethrough increases, in which case the decoupler input member has a radial projection extending radially outward therefrom that is positioned to engage the isolation spring at a selected amount of torque transmission therethrough.

[0054] The decoupler input member includes a radial protrusion arranged to frictionally engage one of the radially outer and inner surfaces of the separation spring when the separation spring reaches a selected radial size, and the frictional engagement between the radial protrusion and the separation spring generates a torque transfer directly from the decoupler input member to the separation spring through the one-way clutch in parallel with the torque transfer from the decoupler input member to the separation spring.

[0055] Thus, in general, it can be said that the decoupler input member includes a radial protrusion arranged to frictionally engage one of the radially outer and inner surfaces of the separation spring when the separation spring reaches a selected radial size, and the frictional engagement between the radial protrusion and the separation spring generates a direct torque transfer from the decoupler input member to the separation spring via the one-way clutch in parallel with the torque transfer from the decoupler input member to the separation spring.

[0056] A decoupler is shown and described herein, and may be for an accessory drive for an engine, particularly a vehicle engine as shown, or for any other suitable type of engine.

[0057] While the description contained herein constitutes several embodiments of the present invention, it will be understood that the invention is capable of further modification and alteration without departing from the fair meaning of the appended claims. [Explanation of symbols]

[0058] 10 Engine (Fig. 1) 12 Crankshaft (Fig. 1) 13 Pulley (Fig. 1) 14 Belt(1) 15 Input shaft (Fig. 1) 16 Auxiliary Equipment (Fig. 1) 16a Alternator (Fig. 1) 20 Decoupler (Figure 2) 22 Hub (Figure 3A) 24 Pulley (Fig. 2) 26 First bearing member (FIG. 3A) 27 Second bearing member (FIG. 3A) 28 Separation spring (Fig. 3A) 30 Carrier (Figure 3A) 32 Wrap spring clutch (Fig. 3A) 40 Outer surface (Fig. 2) 42 Groove (Fig. 2) 43 Inner surface (Fig. 3A) 46 Proximal end (Figure 3A) 47 Distal end (Figure 3A) 48 Groove (Fig. 3A) 50 First spiral end (FIG. 3A) 51 First end of wrap spring clutch (FIG. 3A) 51a Curved part (Fig. 3B) 52 Radially extending driving wall (Figure 3A) 53 Second annular end (Figure 3A) 55 Annular support surface (Figure 3A) 57 Driving wall (Figure 3B) 58 Coil (Figure 3A) 59 Second end of wrap spring clutch (FIG. 3A) 66 Sleeve (Fig. 3A) 80 carrier slots (Figure 3A) 84 Cover (Fig. 2) 100 Support surface (Fig. 4) 102 Inner protrusion (Fig. 4) 150 Anti-ramp driving feature (Figure 3A) 152 Tab (Fig. 3A) 154 Support member (Fig. 3A) 156 Circumferential clearance (Fig. 7C) 158 Receiving surface (Fig. 7C) 200 Decoupler (Figure 5A) 222 Hub (Fig. 5A) 224 Pulley (Fig. 5A) 226 First bearing member (FIG. 5A) 227 Second bearing member (FIG. 5A) 228 Separation spring (Fig. 5A) 230 Carrier (Figure 5A) 232 Wrap spring clutch (Fig. 5A) 300 Support surface (Figure 5A) 302 Thrust member (Fig. 5A) 350 Anti-ramp driving feature (Figure 6A) 352 Anti-ramp engagement feature (FIG. 6A) 422 Hub (Fig. 10A) 430 Carrier (Fig. 10A) 500 Carrier Retainer Slot (Fig. 10A) 502 Entrance slot (Fig. 10B) 504 Anti-ramp drive feature (FIG. 10A) 505 Hub end (Fig. 12A) 506 Drive receiving surface (Fig. 10A) 508 Radial inward protrusion (FIG. 10A) 510 Annular body (Fig. 11A) 514 Bridge (Fig. 11A)

Claims

1. 1. In an endless drive arrangement for transmitting power between an engine and an accessory of a vehicle, a decoupler for mounting on a shaft and for engaging an endless drive member, comprising: a decoupler input member and a decoupler output member, the decoupler output member being rotatable relative to the decoupler input member, the decoupler input member or the decoupler output member being configured to engage the endless drive member; a wrap spring clutch and a separation spring arranged to transfer torque in series between the decoupler input member and the decoupler output member; a carrier arranged to hold an end of the wrap spring clutch and an end of the split spring to enable torque transfer between the end of the wrap spring clutch and the end of the split spring; Equipped with A decoupler, wherein the wrap spring clutch is arranged to transmit torque between the separation spring and one of the decoupler input member and the decoupler output member, and the carrier is supported on a support surface fixed to the one of the decoupler input member and the decoupler output member.

2. 2. A decoupler as claimed in claim 1, wherein said one of said decoupler input member and said decoupler output member is said decoupler input member.

3. 3. The decoupler of claim 2, further comprising an anti-ramp drive feature fixed to the other of the decoupler input member and the decoupler output member and arranged to drive the carrier into rotation with the decoupler output member if the decoupler output member overruns the decoupler input member.

4. 2. The decoupler of claim 1, wherein the decoupler input member is a pulley and the decoupler output member is a hub attachable to a shaft of the accessory.

5. the separation spring is positioned to transfer torque between the wrap spring clutch and the other of the decoupler input member and the decoupler output member; the other of the decoupler input member and the decoupler output member has a carrier retainer slot extending circumferentially on a surface thereof, an entry slot extending at least partially axially at a first end of the carrier retainer slot, and an anti-rump drive feature at a second end of the carrier retainer slot; 2. The decoupler of claim 1, wherein the carrier includes a radially inward protrusion having an anti-ramp drive receiving surface thereon, the carrier is mountable to the other of the decoupler input member and the decoupler output member such that the radially inward protrusion is insertable along the entrance slot to reach the carrier retainer slot, the carrier is moveable along the carrier retainer slot, and when the decoupler output member overruns the decoupler input member, the anti-ramp drive feature engages the anti-ramp drive receiving surface to drive the carrier to rotate with the other of the decoupler input member and the decoupler output member.

6. 1. In an endless drive arrangement for transmitting power between an engine and at least one accessory of a vehicle, a decoupler for mounting on a shaft and engaging an endless drive member, the decoupler comprising: a decoupler input member and a decoupler output member, the decoupler output member being rotatable relative to the decoupler input member, and either the decoupler input member or the decoupler output member being configured to engage the endless drive member; a wrap spring clutch and a separation spring arranged to transfer torque in series between the decoupler input member and the decoupler output member; a carrier arranged to hold an end of the wrap spring clutch and an end of the split spring to enable torque transfer between the end of the wrap spring clutch and the end of the split spring; Equipped with the wrap spring clutch is arranged to transfer torque between the separation spring and one of the decoupler input member and the decoupler output member, and the separation spring is arranged to transfer torque between the wrap spring clutch and the other of the decoupler input member and the decoupler output member; The other of the decoupler input member and the decoupler output member has a circumferentially extending carrier retainer slot on a surface thereof, an entry slot extending at least partially axially at a first end of the carrier retainer slot, and an anti-rump drive feature at a second end of the carrier retainer slot. A decoupler, wherein the carrier includes a radially inward protrusion having an anti-ramp drive receiving surface on a surface thereof, the carrier is attachable to the other of the decoupler input member and the decoupler output member such that the radially inward protrusion is insertable along the entrance slot to reach the carrier retainer slot, the carrier is movable along the carrier retainer slot, and when the decoupler output member overruns the decoupler input member, the anti-ramp drive feature engages the anti-ramp drive receiving surface to drive the carrier to rotate with the one of the decoupler input member and the decoupler output member.

7. 7. A decoupler as claimed in claim 6, wherein said one of said decoupler input member and said decoupler output member is said decoupler input member.

Images