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 over- running 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; and FIG. 2 is a partial cross-section view, taken along the line 2-2 of FIG. 1, of the over- running clutch pulley of the first preferred embodiment; FIG. 3 is a partial cross-section view, similar to FIG. 2, of the over-running clutch pulley of the second preferred embodiment; FIG. 4 is a partial cross-section view, similar to FIG. 2, of the over-running clutch pulley of the third preferred embodiment; and FIG. s 5 and 6 are partial cross-section views, similar to FIG. 2, of the over-running clutch pulley of two variations of the fourth preferred embodiment.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT The following description of the four 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 first preferred embodiment includes a sheave member 20, a hub member 22 located substantially concentrically within the sheave member 20, a clutch member 24, a sealing member 26, and a shielding member 27.

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 sheave clutch surface 32 and the hub clutch surface 38 cooperate to define an open clutch cavity 40 for the clutch member. The sealing member 26, which is preferably coupled to the sheave member 20 and to the hub member 22, is preferably adapted to seal the open clutch cavity 40, while the shielding member 27 is preferably adapted to shield the sealing member 26. The sealing member 26 and the shielding member 27 cooperate to increases wear resistance by retaining lubricant within the open clutch cavity, while minimizing the costs and weight of the over-running clutch pulley 10.

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 42 with two sheave input shoulders 44 and at least one sheave input groove 46.

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 42 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 48 that corresponds to the surface of the cylindrical shaft. The over-running clutch pulley 10 preferably uses a fastening device 50, also called a"threaded nut,"to prevent rotational and axial slippage. 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 48 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 52, which functions to allow relative rotational movement of the sheave member 20 and the hub member 22. The bearing member 52, which is preferably a rolling element type, preferably includes an outer race element 54 preferably press-fit mounted on the sheave member 20, an inner race element 56 preferably press-fit mounted on the hub member 22, ball bearing elements 58 preferably located between the outer race element 54 and the inner race element 56, and bearing seals 60 preferably extending between the outer race element 54 and the inner race element 56 on either side of the ball bearing elements 58. The bearing member 52 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 52 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 past 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. With this arrangement, the sheave clutch surface 32 and the hub clutch surface 38 preferably cooperate to substantially define the open clutch cavity 40. The term"open clutch cavity"preferably refers to the fact that the clutch member 24 is open to the environment without the sealing member 26.

As a contrast, in an over-running clutch pulley with a closed clutch cavity, the clutch member 24 is substantially sealed from the environment by a combination of the sheave member 20, the hub member 22, and the bearing member 52.

The sheave clutch surface 32 and the hub clutch surface 38 of the first preferred embodiment are located substantially adjacent with an axial gap 62 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. Furthermore, the sheave clutch surface 32 and the hub clutch surface 38 preferably have a similar radial diameter, a similar axial length, and a similar smooth finish.

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, which is preferably positioned over the axial gap 62, 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 64. The coil spring 64, which is made from conventional materials and with conventional methods, accomplishes the above features by the particular size and orientation of the coil spring 64. In alternative embodiments, the clutch member 24 may include other suitable devices that accomplish the above features.

The coil spring 64 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 and when experiencing no rotational movement of the sheave member 20 or the hub member 22, the coil spring 64 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 64 is preferably oriented 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 clutch member 24. 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 64 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 64.

The unwinding of the coil spring 64 tends to increase the outward force of the coil spring 64 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 64 tends to decrease the outward force of the coil spring 64 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 64 will lightly rub across the sheave clutch surface 32 or the hub clutch surface 38, which may cause wear of these surfaces. Similarly, during the"lock"condition of the over-running clutch pulley 10, the coil spring 64 will forcefully engage with the sheave clutch surface 32 and the hub clutch surface 38, which may also cause wear of these surfaces. To resist the wear of these surfaces, the sheave clutch surface 32 and the hub clutch surface 38 are preferably formed or treated to have a sufficient surface hardness value.

To insure the proper placement of the clutch member 24, the sheave member 20 of the first preferred embodiment includes a sheave flange section 66 defining a sheave flange surface 68, and the hub clutch section 36 of the preferred embodiment defines a hub flange surface 70.

The sheave flange section 66 preferably extends radially inward adjacent the sheave clutch section 30. The sheave flange surface 68 and the hub flange surface 70 are preferably located on opposite ends of the clutch member 24. The over-running clutch pulley 10 of the preferred embodiment may, of course, use other suitable devices to insure the proper placement of the clutch member 24. These devices may be surfaces defined by other sections of the sheave member 20 or the hub member 22, or surfaces defined by other suitable elements. In the same manner as the sheave clutch surface 32 and the hub clutch surface 38, the sheave flange surface 68 and the hub flange surface 70 are preferably formed or treated to have a sufficient surface hardness value.

The sealing member 26 of the first preferred embodiment functions to seal the open clutch cavity 40, thereby protecting the clutch member 24 from contaminants and retaining a lubricant (not shown) within the open clutch cavity 40. The sealing member 26 is preferably rotationally engaged with the sheave flange section 66 of the sheave member 20, and slidably coupled with the hub member 22 via a lip seal 86, which functions to allow relative rotational movement between the sealing member 26 and the hub member 22. The sealing member 26 may alternatively be coupled with any surface or section of the sheave member 20 and the hub member 22 such that the sealing member 26 substantially seals the open clutch cavity 40. The sealing member 26 is preferably made from conventional materials, such as a polymeric material, and with conventional methods, but may alternatively be made from any suitable material and with any suitable method.

The fastening device 50 of the first preferred embodiment functions to axially retain the hub member 22 against the output device and, for this reason, the fastening device 50 preferably includes a threaded section (not shown) that corresponds to a threaded section on the cylindrical shaft of the output device. The fastening device 50 may, however, alternatively include other suitable devices or methods to axially retain the hub member 22 against the output device. The fastening device 50 is preferably made from conventional structural materials, such as steel, and with conventional methods, but may alternatively be made from other suitable materials and with other suitable methods.

The shielding member 27 of the first preferred embodiment functions to at least partially shield the sealing member 26. The term"shield"connotes the fact that, while there may be gaps between the sealing member 26 and the shielding member 27, the shielding member 27 provides some protection against the elements and contaminants. In the preferred embodiment, the shielding member 27 shields the lip seal 86 of the sealing member 26, but the shielding member 27 may alternatively shield other sections or portions of the sealing member 26. In the first preferred embodiment, the shielding member 27 is integrally formed with the fastening device 50. For this reason, the shielding member 27 is preferably made from the same material as the fastening device 50.

As shown in FIG. 3, the shielding member 27'of the second preferred embodiment is preferably separately formed and later connected to the fastening device 50'of the second preferred embodiment. In all other respects, the over-running clutch pulley 10'of the second preferred embodiment is preferably similar to the over-running clutch pulley 10 of the first preferred embodiment. The shielding member 27'is preferably made from conventional materials, such as a polymeric material, and with conventional methods, but may alternatively be made from any suitable material and with any suitable method.

As shown in FIG. 4, the shielding member 27"of the third preferred embodiment is preferably mounted over the sealing member 26. The shielding member 27"is preferably rotationally engaged to the sheave flange section 66 of the sheave member 20. In this manner, the shielding member 27"acts like a"lens cap"for a camera. In all other respects, the over- running clutch pulley 10"of the third preferred embodiment is preferably similar to the over- running clutch pulley 10 of the first preferred embodiment. The shielding member 27"is preferably made from conventional materials, such as a polymeric material, and with conventional methods, but may alternatively be made from any suitable material and with any suitable method.

As shown in FIG. s 5 and 6, the shielding member 27"'of the fourth preferred embodiment is preferably rotationally engaged against the sealing member 26 with a locking element 92. In a first variation of the fourth preferred embodiment, as shown in FIG. 5, the locking device 92 is preferably shaped to allow easy engagement with the sealing member 26, but to resist disengagement from the sealing member 26. In a second variation of the fourth embodiment, as shown in FIG. 6, the locking device 92'is preferably shaped to bias the shielding member 27"'against the sealing member 26. The locking device 92 and 92'is preferably made from conventional materials, such as plastic in the first variation and steel in the second variation, and with conventional methods, but may alternatively be made from other suitable materials and with other suitable methods.

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 embodiment of the invention without departing from the scope of this invention defined in the following claims.