WO2001092743A1

WO2001092743A1 - Over-running clutch pulley with open clutch cavity

Info

Publication number: WO2001092743A1
Application number: PCT/US2001/017522
Authority: WO
Inventors: Randall King; Russell Monahan; John Miller; Robert Frayer
Original assignee: Ntn Corporation
Priority date: 2000-05-31
Filing date: 2001-05-31
Publication date: 2001-12-06
Also published as: EP1284831A1; WO2001092745A1; WO2001092746A1; WO2001092747A1; EP1208312A1; WO2001092740A1; JP2003535280A; EP1208318A1; WO2001092741A1; EP1208315A4; JP2003535287A; WO2001092760A1; EP1284832A1; JP2003535278A; JP2003535279A; WO2001092742A1; EP1208314A1; EP1208315A1; WO2001091938A1; EP1208316A1

Abstract

An over-running clutch pulley (10) preferably includes a sheave member (20), a hub member (22) located substantially concentrically within the sheave member, a clutch member (24), and an end cap (26). The sheave member preferably includes a sheave input section (28) adapted to engage the input device (12), and a sheave clutch section (30) defining a sheave clutch surface (32). Similarly, the hub member preferably includes a hub output section (34) adapted to engage the output device (14), and a hub clutch section (36) defining a hub clutch surface (38). In the preferred embodiment, the sheave clutch surface and the hub clutch surface cooperate to substantially define an open clutch cavity (40). The end cap, which is preferably fastened to the sheave member, is preferably adapted to substantially seal the open clutch cavity.

Description

OVER-RUNNING CLUTCH PULLEY WITH OPEN CLUTCH CAVITY

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.

Despite the success of the over-running clutch pulley of the above-identified patent, there is a continual desire to reduce the weight and cost of nearly every component of an automobile. This invention provides an over-running clutch pulley with features intended to reduce weight and cost.

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 overrunning clutch pulley of the preferred embodiment.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT The following description of the preferred embodiment of the invention is not intended to limit the scope of this invention to this preferred embodiment, 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 an end cap 26. 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 substantially define an open clutch cavity 40. The end cap 26, which is preferably fastened to the sheave member 20, is preferably adapted to substantially seal the open clutch cavity 40 and to axially retain the clutch member 24 within the open clutch cavity 40. This arrangement, which omits a section of the sheave member 20 to axially retain the clutch member 24 within the open clutch cavity 40, has a reduced weight and cost compared with conventional driven pulleys.

The sheave input section 28 of the sheave member 20 of the 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 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 preferably uses a threaded nut 50 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 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 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 (as described below). The sheave clutch surface 32 preferably includes a tampered section 61 that functions to allow easier insertion of the clutch member 24 into the open clutch cavity 40, but may alternatively include a straight section with a cylindrical shape. 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 (as described below). 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 end cap 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. In the preferred embodiment, the sheave clutch surface 32 and the hub clutch surface 38 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 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 within the open clutch cavity 40. 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 into the open clutch cavity 40 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 within the open clutch cavity 40 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 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.

In addition to substantially sealing the open clutch cavity 40, the end cap 26 also preferably functions to axially retain the clutch member 24 within the open clutch cavity 40. To avoid accidental winding or unwinding of the clutch member 24, the end cap 26 is preferably fastened to a sheave flange surface 72 of the sheave member 20 by a crimping or swaging method. The end cap 26 may alternatively be coupled to any suitable surface on the sheave member with any suitable device or method. The end cap 26 preferably performs the axial retention function in cooperation with a hub flange surface 66 defined by the hub clutch section 36. Other suitable surfaces or devices, however, may cooperate with the end cap 26 to axially retain the clutch member 24 within the open clutch cavity 40.

The end cap 26 of the preferred embodiment includes a cap extension 68, which functions to couple the end cap 26 to the hub member 22 and to seal the open clutch cavity 40. Because the end cap 26 is preferably fastened to the sheave member 20 and because the sheave member 20 rotates relative to the hub member 22, the cap extension 68 is preferably slidably connected to the hub member 22 with a lip seal 70. The cap extension 68 may alternatively be coupled to any suitable surface on the hub member 22 with any suitable device or method.

In addition to allowing relative rotational movement of the sheave member 20 and the hub member 22, the bearing member 52 also preferably functions to position the sheave member 20 and the hub member 22 such that the sheave member 20 and the hub member 22 define a radial gap 74. In the preferred embodiment, the radial gap 74 and the axial gap 62 interconnect to substantially prevent contact between the sheave member 20 and the hub member 22. Further, in the preferred embodiment, the radial gap 74 and the axial gap 62 communicate with the bearing member 52. In this manner, the bearing member 52 may omit the bearing seal 60 facing the clutch member 24 if the over-running clutch pulley includes a grease material compatible with the bearing member 52 and the clutch member 24.

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.

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 extending inwardly from said sheave input section and defining a sheave clutch surface substantially adjacent said 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 extending outwardly from and axially past said hub output section and defining a hub clutch surface, wherein said sheave clutch surface and said hub clutch surface cooperate to substantially define an open clutch cavity; a clutch member located substantially within said open clutch cavity and adapted to engage 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 disengage 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; and an end cap fastened to said sheave member and adapted to substantially seal said open clutch cavity.

2. The over-running clutch pulley of Claim 1 wherein said sheave input section defines a sheave input surface with two sheave shoulders and at least one sheave input groove 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.

3. The over-running clutch pulley of Claim 1 wherein said sheave clutch surface is inwardly directed and substantially cylindrically shaped.

4. The over-running clutch pulley of Claim 1 wherein said sheave clutch surface is tapered to allow easier insertion of said clutch member into said open clutch cavity.

5. 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.

6. The over-running clutch pulley of Claim 1 wherein said hub clutch surface is inwardly directed and substantially cylindrically shaped.

7. The over-running clutch pulley of Claim 1 wherein said end cap is adapted to axially retain said clutch member.

8. The over-running clutch pulley of Claim 1 wherein said end cap includes a cap extension extending axially towards and sealing against said hub member.

9. The over-running clutch pulley of Claim 8 wherein said end cap slides relative said hub member during relative rotational movement of said sheave member and said hub member.

10. 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.

11. The over-running clutch pulley of Claim 1 wherein said sheave clutch surface and said hub clutch surface define an axial gap, and wherein said clutch member is positioned substantially over said axial gap.

12. The over-running clutch pulley of Claim 1 1 wherein said bearing member is further adapted to position said sheave member and said hub member such that said sheave member and said hub member define a radial gap, and wherein said radial gap and said axial gap interconnect.

13. The over-running clutch pulley of Claim 11 wherein said radial gap communicates with said bearing member.