OVER-RUNNING CLUTCH PULLEY WITH SLIP INFLUENCE

Abstract: The over-running clutch pulley (10) of a preferred embodiment of the invention includes a sheave member (20), a hub member (22) located substantially concentrically within the sheave member, a clutch member (24), and slip influencing means (26), which cooperate to rotationally engage an input device (12) and an output device (14). The sheave member preferably includes a sheave input section (28) adapted to engage the input device, and a sheave clutch section (30) defining a sheave clutch surface. Similarly, the hub member preferably includes a hub output section (34) adapted to engage the output device, and a hub clutch section (36) defining a hub clutch surface. In the preferred embodiment, the slip influencing means influences the clutch member to remain substantially engaged to the hub clutch surface and to slip against the sheave clutch surface upon the deceleration of the sheave member in the first rotational direction relative the hub member.

Description: U 01 17639 OVER-RUNNING CLUTCH PULLEY WITH SLIP INFLUENCE TECHNICAL FIELD This invention relates generally to devices in the over-running clutch field, and more specifically to an improved over-running clutch pulley for use with an accessory device driven by an automotive engine with a belt drive. BACKGROUND During the operation of an automotive engine, a drive belt is typically used to power and operate various accessory devices. One of these accessory devices is typically an automotive alternator, which provides electrical power to the automobile. While several arrangements of drive belts are in use, the serpentine arrangement, which drives several accessory devices, is currently most favored. Serpentine arrangements typically include a drive pulley connected to the crankshaft of the engine (the "output device") and a drive belt trained about the drive pulley. The drive belt is also trained about one or more conventional driven pulleys, which are connected to the input shafts of various accessories devices (the "input device"). Most conventional driven pulleys are made from a one-piece design with no overrunning capabilities. In other words, the conventional driven pulleys are rigidly mounted to the input shaft and are incapable of allowing relative rotational movement between any section of the driven pulley and the input shaft. As a result of the lack of any over-running capabilities and of the generation of significant inertia by the accessory, relative slippage between the drive belt and the driven pulley may occur if the drive belt suddenly decelerates relative to the input shaft. The relative slippage may cause an audible squeal, which is annoying from an auditory standpoint, and an undue wear on the drive belt, which is undesirable from a mechanical standpoint. In a typical driving situation, the drive belt may experience many instances of sudden deceleration relative to the input shaft. This situation may occur, for example, during a typical shift from first gear to second gear under wide open throttle acceleration. This situation is worsened if the throttle is closed or "back off immediately after the shift. In these situations, the drive belt decelerates very quickly while the driven pulley, with the high inertia from the accessory device, maintains a high rotational speed, despite the friction between the drive belt and the driven pulley. In addition to the instances of sudden deceleration, the drive belt may experiences other situations that cause audible vibration and undue wear. As an example, a serpentine arrangement with conventional driven pulleys may be used with an automobile engine that has an extremely low idle engine speed (which may increase fuel economy). In these situations, the arrangement typically experiences "belt flap" of the drive belt as the periodic cylinder firing of the automotive engine causes the arrangement to resonate within a natural frequency and cause an audible vibration and an undue wear on the drive belt. The disadvantage of the conventional driven pulleys, namely the audible squeal, the undue wear, and the vibration of the drive belt, may be avoided by the use of an over-running clutch pulley instead of the conventional driven pulley. An over-running clutch pulley allows the pulley to continue to rotate at the same rotational speed and in a same rotational direction after a sudden deceleration of the drive belt. In a way, the over-running clutch pulley functions like the rear hub of a typical bicycle; the rear hub and rear wheel of a conventional bicycle continue to rotate at the same rotational speed and in the same rotational direction even after a sudden deceleration of the pedals and crankshaft of the bicycle. An example of an over-running clutch pulley is described in U.S. Patent No. 5,598,913 issued to the same assignee of this invention and hereby incorporated in its entirety by this reference. Since many customers of new automobiles are demanding longer lives, with relatively fewer repairs, for their new automobiles, there is a need in the automotive field, if not in other fields, to create an over-running clutch pulley with increased wear resistance. This invention provides an over-running clutch pulley with features intended to increase wear resistance, while minimizing the costs and weight of the over-running clutch pulley. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of an over-running clutch pulley of the invention, shown with a drive belt as the input device and a cylindrical shaft as the output device; FIG. 2 is a partial cross-section view, taken along the line 2-2 of FIG. 1 , of the overrunning clutch pulley of a first and second preferred embodiment; FIG. 3 is an exaggerated close-up view of the over-running clutch pulley of FIG. 2, shown with the hub clutch surface defining a diameter less than the sheave clutch surface; FIG. 4 is a close-up view of the over-running clutch pulley of FIG. 2, shown with a friction coating; and FIG. 5 is a partial cross-section view, similar to FIG. 2, of the over-running clutch pulley of a third preferred embodiment; and FIG. 6 is a partial cross-section view, taken along the line 6-6 of FIG. 5, of the overrunning clutch pulley of a third preferred embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The following description of three preferred embodiments of the invention is not intended to limit the scope of this invention to these preferred embodiments, but rather to enable any person skilled in the art of over-running clutches to make and use this invention. As shown in FIG. 1 , the invention includes an over-running clutch pulley 10 for rotationally engaging an input device 12 and an output device 14. The over-running clutch pulley 10 has been designed for use with a drive belt 16 as the input device 12, and with a cylindrical shaft 18 as the output device 14. More specifically, the over-running clutch pulley 10 has been particularly designed for use with a drive belt 16 with a grooved surface and a cylindrical shaft 18 of an automotive alternator. The over-running clutch pulley 10 may be used, however, in other environments, with other suitable input devices, such as smooth belt, a toothed belt, a V- shaped belt, or even a toothed gear, and with other suitable output devices, such as a polygonal shaft. Furthermore, the over-running clutch pulley 10 may be used in an environment with two devices that alternate their rotational input responsibilities, and in an environment with an "output device" that actually provides rotational input and with an "input device" that actually receives rotational input. In these alternative embodiments, the terms "input device" and "output device" are interchangeable. As shown in FIG. 2, the over-running clutch pulley 10 of the preferred embodiment includes a sheave member 20, a hub member 22 located substantially concentrically within the sheave member 20, a clutch member 24, and a slip influencing means 26, which cooperate to rotationally engage the drive belt and the cylindrical shaft. The sheave member 20 preferably includes a sheave input section 28 adapted to the engage the input device, and a sheave clutch section 30 defining a sheave clutch surface 32. Similarly, the hub member 22 preferably includes a hub output section 34 adapted to engage the output device, and a hub clutch section 36 defining a hub clutch surface 38. In the preferred embodiment, the slip influencing means 26 influences the clutch member 24 to lock against the hub clutch surface 38 and to slip against the sheave clutch surface 32 upon the deceleration of the sheave member 20 in the first rotational direction relative the hub member 22, which increases wear resistance for the over-running clutch pulley 10, while minimizing cost and weight. The over-running clutch pulley of alternative embodiments may include other elements, such as a sealing member to substantially prevent passage of dirt into and grease out of the over-running clutch pulley, or any other suitable elements that do not substantially interfere with the functions of the sheave member 20, the hub member 22, the clutch member 24, and the slip influencing means 26. The sheave input section 28 of the sheave member 20 of the first preferred embodiment functions to engage the drive belt. To substantially prevent rotational and axial slippage of the sheave member 20 and the drive belt, the sheave input section 28 preferably defines a sheave input surface 40 with two sheave input shoulders 42 and at least one sheave input groove 44. The sheave input section 28 may alternatively define other suitable surfaces, such as toothed surfaces or ribbed surfaces, to engage the input device. The sheave input surface 40 is preferably outwardly directed (away from the rotational axis of the over-running clutch pulley 10) and is preferably substantially cylindrically shaped. The sheave input section 28 is preferably made from conventional structural materials, such as steel, and with conventional methods, but may alternatively be made from other suitable materials and from other suitable methods. The hub output section 34 of the hub member 22 of the first preferred embodiment functions to engage the cylindrical shaft. The hub output section 34 preferably defines a hub output surface 46 with a smooth section 48 (which functions to ease and center the assembly of the over-running clutch pulley 10 onto the cylindrical shaft), a threaded section 50 (which functions to substantially prevent rotation and to axially retain the hub member 22 to the cylindrical shaft), and a hexagonal section 52 (which functions to mate with an alien wrench for easy tightening and loosening of the over-running clutch pulley 10 onto and off of the cylindrical shaft). Of course, the hub output section 34 may include other suitable devices or define other surfaces to prevent rotational and axial slippage, to engage the cylindrical shaft, and to engage a tool for tightening or loosening the over-running clutch pulley 10 onto and off of the cylindrical shaft. The hub output surface 46 is preferably inwardly directed (toward the rotational axis of the over-running clutch pulley 10) and is preferably substantially cylindrically shaped. The hub output section 34 is preferably made from conventional structural materials, such as steel, and with conventional methods, but may alternatively be made from other suitable materials and from other suitable methods. The over-running clutch pulley 10 of the first preferred embodiment also includes a bearing member 54, which functions to allow relative rotational movement of the sheave member 20 and the hub member 22. The bearing member 54, which is preferably a rolling element type, preferably includes an outer race element 56 preferably press-fit mounted on the sheave member 20, an inner race element 58 preferably press-fit mounted on the hub member 22, ball bearing elements 60 preferably located between the outer race element 56 and the inner race element 58, and bearing seals 62 preferably extending between the outer race element 56 and the inner race element 58 on either side of the ball bearing elements 60. The bearing member 54 may alternatively be of other suitable types, such as a journal bearing or a roller bearing, may alternatively include other suitable elements, and may alternatively be mounted in other suitable manners. The bearing member 54 is a conventional device and, as such, is preferably made from conventional materials and with conventional methods, but may alternatively be made from other suitable materials and with other suitable methods. The sheave clutch section 30 and the hub clutch section 36 of the first preferred embodiment function to provide the sheave clutch surface 32 and the hub clutch surface 38, respectively, for the engagement with the clutch member 24. The sheave clutch section 30 preferably extends radially inward from the sheave member 20. In this manner, the sheave clutch section 30 is preferably made from the same material and with the same methods as the sheave input section 28, but may alternatively be made from other suitable materials and with other suitable methods. The hub clutch section 36 preferably extends radially outward from and axially over the hub output section 34. In this manner, the hub clutch section 36 is preferably made from the same material and with the same methods as the hub output section 34, but may alternatively be made from other suitable materials and with other suitable methods. The hub clutch section 36 preferably partially defines a closed clutch cavity 64 to contain the clutch member 24. In the first preferred embodiment, the sheave clutch surface 32 and the hub clutch surface 38 are located substantially adjacent with an axial gap 66 between each other. The sheave clutch surface 32 and the hub clutch surface 38 are preferably inwardly directed (toward the rotational axis of the over-running clutch pulley 10) and are preferably substantially cylindrically shaped. These features allow optimum performance of the clutch member 24. The sheave clutch surface 32 and the hub clutch surface 38 may alternatively have differences with each other on these, or other, design specifications. The clutch member 24 of the first preferred embodiment functions to engage the sheave clutch surface 32 and the hub clutch surface 38 upon the acceleration of the sheave member 20 in a first rotational direction relative to the hub member 22, and to disengage the sheave clutch surface 32 and the hub clutch surface 38 upon the deceleration of the sheave member 20 in the first rotational direction relative to the hub member 22. In the preferred embodiment, the clutch member 24 is a coil spring 68. The coil spring 68, which is made from conventional materials and with conventional methods, accomplishes the above features by the particular size and orientation of the coil spring 68 within the closed clutch cavity 64. In alternative embodiments, the clutch member 24 may include other suitable devices that accomplish the above features. The coil spring 68 is preferably designed with a relaxed spring radial diameter that is sized slightly greater than an inner diameter of the sheave clutch surface 32 and the hub clutch surface 38. Thus, when inserted into the closed clutch cavity 64 and when experiencing no rotational movement of the sheave member 20 or the hub member 22, the coil spring 68 frictionally engages with and exerts an outward force on both the sheave clutch surface 32 and the hub clutch surface 38. Further, the coil spring 68 is preferably oriented within the closed clutch cavity 64 such that the coils extend axially in the first rotational direction from the sheave clutch surface 32 to the hub clutch surface 38. With this orientation, relative rotational movement of the sheave member 20 and the hub member 22 will result in an unwinding or winding of the spring member. In other words, acceleration of the sheave member 20 in the first rotational direction relative to the hub member 22 will bias an unwinding of the coil spring 68 and deceleration of the sheave member 20 in the first rotational direction relative to the hub member 22 will bias a winding of the coil spring 68. The unwinding of the coil spring 68 tends to increase the outward force of the coil spring 68 on the sheave clutch surface 32 and the hub clutch surface 38, thereby providing engagement, or "lock", of the sheave member 20 and the hub member 22. This engagement condition preferably occurs upon the acceleration of the sheave member 20 in the first rotational direction relative to the hub member 22. On the other hand, the winding of the coil spring 68 tends to decrease the outward force of the coil spring 68 on the sheave clutch surface 32 and the hub clutch surface 38, thereby allowing disengagement, or "slip", of the sheave member 20 and the hub member 22. This disengagement condition preferably occurs upon the deceleration of the sheave member 20 in the first rotational direction relative to the hub member 22. During the "slip" condition of the over-running clutch pulley 10, the coil spring 68 will lightly rub across the sheave clutch surface 32 or the hub clutch surface 38, which generates heat. The heat generation, which may increase wear of the over-running clutch pulley if not properly dissipated, is most effectively and efficiently dissipated through the sheave member 20, which has more surface area than the hub member 22. For this reason, the slip influencing means 26 of the preferred embodiments function to influence the clutch member 24 to remain substantially engaged to the hub clutch surface 38 and to slip against the sheave clutch surface 32 upon the deceleration of the sheave member 20 in the first rotational direction relative the hub member 22. The slip influencing means 26 is preferably effective in all circumstances. Other factors, however, may affect the behavior of the clutch member 24 and, for this reason, the term "influencing" preferably means "causing in most instances." The slip influencing means 26 may be accomplished with several different structures and methods. As shown in FIG. 3, the slip influencing means 26 of first preferred embodiment includes the hub clutch surface 38 defining a diameter less than the sheave clutch surface 32. As discussed above, deceleration of the sheave member 20 in the first rotational direction relative to the hub member 22 will bias a winding of the coil spring 68, which tends to decrease the outward force of the coil spring 68 on the sheave clutch surface 32 and the hub clutch surface 38. Since the diameter of the sheave clutch surface 32 is greater than the diameter of the hub clutch surface 38, the clutch member 24 will be influenced to disengage, or "slip", against the sheave clutch surface 32 and remain substantially engaged to the hub clutch surface 38. The difference between the diameters of the hub clutch surface 38 and the sheave clutch surface 32 is preferably approximately 1 mm, but may alternatively be larger or smaller so long as the clutch member 24 is properly influenced. Further, while the hub clutch surface 38 preferably has a straight cylinder-shape, the hub clutch surface may alternatively have a sloped conical-shape to ease the transition across the axial gap 66. As shown in FIG. 4, the slip influencing means 26' of the second preferred embodiment includes the hub clutch surface 38' having a coefficient of friction greater than the sheave clutch surface 32. Since the coefficient of friction of the sheave clutch surface 32 is less than the coefficient of friction of the hub clutch surface 38', the clutch member 24 will be influenced to slip against the sheave clutch surface 32 and remain substantially engaged to the hub clutch surface 38'. The difference between the coefficients of friction between the hub clutch surface 38' and the sheave clutch surface 32 is preferably approximately 0.05, but may alternatively be larger or smaller so long as the clutch member 24 is properly influenced. The difference may be accomplished with several different methods or devices, such as forming the hub clutch surface 38' or the sheave clutch surface 32 with a particular coefficient of friction, treating the hub clutch surface 38' or the sheave clutch surface 32 to have a particular coefficient of friction, and coating the hub clutch surface 38' or the sheave clutch surface 32 to have a particular coefficient of friction. While any suitable method or device may be used to provide difference between the coefficients of friction between the hub clutch surface 38' and the sheave clutch surface, disposing a friction coating 69 is preferred. As shown in FIG.s 5 and 6, the slip influencing means 26" of the third preferred embodiment includes the hub clutch surface 38" defining a hub clutch indention 70 and the clutch member 24" including a clutch tang section 72 engagable with the hub clutch indention 70. The clutch tang section 72 preferably extends radially outward in a direction perpendicular to the axis of the clutch member 24". The hub clutch indention 70 is preferably shaped to accommodate the clutch tang section 72. Since the clutch tang section 72 of the clutch member 24" is engagable with the hub clutch indention 70, the clutch member 24" will be influenced to slip against the sheave clutch surface 32 and to remain substantially engaged to the hub clutch surface 38". The over-running clutch pulley 10" of the third preferred embodiment has the added feature that the clutch member 24" may overlap the sheave clutch surface 32 for a greater distance than the clutch member 24" overlap the hub clutch surface 38". In other words, the clutch member 24" may be provided with a ]onger "sheave side" and a shorter "hub side." This particular feature allows for a shorter overall length of the over-running clutch pulley 10" of the third preferred embodiment. In a variation of the third preferred embodiment, the hub clutch surface may define a hub clutch projection (not shown) and the clutch member may define a squared end (not shown), which would preferably function and perform similar to the overrunning clutch pulley of the third preferred embodiment. As any person skilled in the art of over-running clutches will recognize from the previous detailed description and from the figures and claims, modifications and changes can be made to the preferred embodiments of the invention without departing from the scope of this invention defined in the following claims.

Claims: CLAIMS We Claim: 1. An over-running clutch pulley for rotationally engaging an input device and an output device, comprising: a sheave member including a sheave input section adapted to engage the input device, and a sheave clutch section defining a sheave clutch surface; a hub member located substantially concentrically within said sheave member and including a hub output section adapted to engage the output device, and a hub clutch section defining a hub clutch surface substantially adjacent said sheave clutch surface; a clutch member adapted to lock against said sheave clutch surface and said hub clutch surface thereby engaging said sheave clutch surface and said hub clutch surface upon the acceleration of said sheave member in a first rotational direction relative said hub member, and to slip against one of said sheave clutch surface and said hub clutch surface thereby disengaging said sheave clutch surface and said hub clutch surface upon the deceleration of said sheave member in the first rotational direction relative said hub member; slip influencing means for influencing said clutch member to slip against said sheave clutch surface upon the deceleration of said sheave member in the first rotational direction relative said hub member. 2. The over-running clutch pulley of Claim 1 wherein said slip influencing means includes said hub clutch surface defining a diameter less than said sheave clutch surface. 3. The over-running clutch pulley of Claim 1 wherein said slip influencing means includes said hub clutch surface having a coefficient of friction greater than said sheave clutch surface. 4. The over-running clutch pulley of Claim 1 wherein said slip influencing means includes said hub clutch surface defining a hub clutch indention and said clutch member including a clutch tang section engagable with said hub clutch indention. 5. The over-running clutch pulley of Claim 4 wherein said clutch member overlaps said sheave clutch surface for a greater distance than said clutch member overlaps said hub clutch surface. 6. The over-running clutch pulley of Claim 1 wherein said sheave input section defines a sheave input surface with two sheave shoulders and several sheave input grooves that cooperate to engage a grooved belt as the input device and to substantially prevent rotational and axial slippage between said sheave input surface and the grooved belt. 7. The over-running clutch pulley of Claim 1 wherein said sheave clutch surface is inwardly directed and cylindrically shaped. 8. The over-running clutch pulley of Claim 1 further comprising a bearing member located between said sheave member and said hub member, and adapted to allow relative rotational movement of said sheave member and said hub member. 9. The over-running clutch pulley of Claim 1 wherein said hub output section defines a hub output surface adapted to engage a cylindrical shaft as the output device. 10. The over-running clutch pulley of Claim 1 wherein said hub clutch surface is inwardly directed and cylindrically shaped.

Inventors: FRAYER ROBERT, KING RANDALL, MONAHAN RUSSELL, FRAYER, ROBERT, KING, RANDALL, MONAHAN, RUSSELL
Applicants: FRAYER ROBERT, KING RANDALL, MONAHAN RUSSELL, FRAYER, ROBERT, KING, RANDALL, MONAHAN, RUSSELL
Application year: 2001
Main classification: F16D13
IPC codes: B21K1, B21K25, B23P11, B23P15, C10M101, C10M105, C10M115, C10M117, C10M169, C10N10, C10N30, C10N40, C10N50, F16C19, F16C33, F16C35, F16D13, F16D41, F16D43, F16H35, F16H55, F16J15