EP1284831A1

EP1284831A1 - Method of manufacturing an over-running clutch pulley with retention member

Info

Publication number: EP1284831A1
Application number: EP01939788A
Authority: EP
Inventors: John Miller; Yoshikazu Terada; Robert Frayer; William Allison; Gail Sharp; Randall King
Original assignee: NTN Corp; NTN Toyo Bearing Co Ltd
Current assignee: NTN Corp
Priority date: 2000-05-31
Filing date: 2001-05-31
Publication date: 2003-02-26
Also published as: WO2001091938A1; WO2001092746A1; JP2003535281A; JP2003535273A; EP1208311A1; EP1208316A1; JP2004514092A; JP2003535280A; JP2003535282A; WO2001092740A1; EP1285177A1; WO2001092742A1; JP2003535287A; EP1208310A1; WO2001091939A1; JP2004501326A; EP1284832A1; EP1208314A1; EP1208310A4; EP1208312A1

Abstract

A method of manufacturing an over-running clutch pulley for rotationally engaging an input device and an output device including providing a sheave member (20), a hub member (22), a bearing member (24), a retention member (26), and a clutch member (28). In a first preferred method, the retention member (26) is provided as a metallic snap ring and inserted into a retention slot (80). In a second preferred embodiment, the retention member (26) is molded into a mold cavity (86, 96). In both methods, the retention member preferably functions to axially retain the bearing member relative to the sheave member and the hub member.

Description

METHOD OF MANUFACTURING AN OVER-RUNNING CLUTCH PULLEY WITH RETENTION MEMBER

TECHNICAL FIELD This invention relates generally to methods of manufacturing devices in the over-running clutch field, and more specifically to an improved method of manufacturing over-running clutch pulleys 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 "backed 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 structural rigidity. This invention provides an improved method of manufacturing an over-running clutch pulley that includes features intended to increase structural rigidity, while minimizing the cost and weight of the overrunning clutch pulley.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of an over-running clutch pulley made with the preferred methods 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 made with the first preferred method;

FIG. 3 is a partial cross-section view, similar to FIG. 2, of the over-running clutch pulley made with the second preferred method; and

FIG. 4 is a partial cross-section view shown with the mold tool involved in the second preferred method.

DETAILED DESCRIPTION OF THE PREFERRED METHODS The following description of two preferred methods of the invention is not intended to limit the scope of this invention to these preferred methods, 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 , an over-running clutch pulley 10 made with the preferred methods of the invention rotationally engages 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 made with the first and second preferred methods includes a sheave member 20, a hub member 22 located substantially concentrically within the sheave member 20, a bearing member 24 located between the sheave member 20 and the hub member 22, a retention member 26, and a clutch member 28, which cooperate to rotationally engage the drive belt and the cylindrical shaft. The sheave member 20 preferably includes a sheave input section 30 adapted to the engage the input device, and a sheave clutch section 32 defining a sheave clutch surface 34. Similarly, the hub member 22 preferably includes a hub output section 36 adapted to engage the output device, and a hub clutch section 38 defining a hub clutch surface 40. The retention member 26 preferably functions to axially retain the bearing member 24 relative to the sheave member 20 and the hub member 22. The retaining of the bearing member 24 in this manner increases structural rigidity, while minimizing cost and weight of the over-running clutch pulley 10.

The sheave input section 30 of the sheave member 20 involved in the preferred methods 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 30 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 30 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 30 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 36 of the hub member 22 involved in the preferred methods functions to engage the cylindrical shaft. The hub output section 36 preferably defines a hub output surface 48 with a smooth section 50 (which functions to ease and center the assembly of the over-running clutch pulley 10 onto the cylindrical shaft), a threaded section 52 (which functions to substantially prevent rotation and to axially retain the hub member 22 to the cylindrical shaft), and a hexagonal section 54 (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 36 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 36 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 bearing member 24 involved in the preferred methods functions to allow relative rotational movement of the sheave member 20 and the hub member 22. The bearing member 24, which is preferably a rolling element type, preferably includes an outer race element 56 preferably press-fit mounted in the sheave member 20, an inner race element 58 preferably press-fit mounted in 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 24 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 24 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 32 of the sheave member 20 and the hub clutch section 38 of the hub member 22 involved in the preferred methods function to provide the sheave clutch surface 34 and the hub clutch surface 40, respectively, for the engagement with the clutch member 28. The sheave clutch section 32 preferably extends radially inward from the sheave member 20. In this manner, the sheave clutch section 32 is preferably made from the same material and with the same methods as the sheave input section 30, but may alternatively be made from other suitable materials and with other suitable methods. The hub clutch section 38 preferably extends radially outward from and axially over the hub output section 36. In this manner, the hub clutch section 38 is preferably made from the same material and with the same methods as the hub output section 36, but may alternatively be made from other suitable materials and with other suitable methods. The hub clutch section 38 preferably partially defines a closed clutch cavity 64 to contain the clutch member 28.

In the over-running clutch pulley made with the preferred methods, the sheave clutch surface 34 and the hub clutch surface 40 are located substantially adjacent with an axial gap 66 between each other. The sheave clutch surface 34 and the hub clutch surface 40 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 34 and the hub clutch surface 40 preferably have a similar radial diameter, a similar axial length, and a similar smooth finish. These features allow optimum performance of the clutch member 28. The sheave clutch surface 34 and the hub clutch surface 40 may alternatively have differences with each other on these, or other, design specifications.

The clutch member 28 involved in the preferred methods functions to engage the sheave clutch surface 34 and the hub clutch surface 40 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 34 and the hub clutch surface 40 upon the deceleration of the sheave member 20 in the first rotational direction relative to the hub member 22. In the preferred method, the clutch member 28 involves 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 methods, the clutch member 28 may involve other suitable devices that accomplish the above features.

The coil spring 68 involved in the preferred methods is preferably designed with a relaxed spring radial diameter that is sized slightly greater than an inner diameter of the sheave clutch surface 34 and the hub clutch surface 40. 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 34 and the hub clutch surface 40. 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 34 to the hub clutch surface 40. 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 34 and the hub clutch surface 40, 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 34 and the hub clutch surface 40, 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.

A misalignment of the input device, the output device, and the over-running clutch pulley may cause contact between the sheave member 20 and the hub member 22 during the relative rotational movement of the sheave member 20 and the hub member 22. Further, prolonged contact between the sheave member 20 and hub member 22 may cause wear of these elements. To resist wear, the axial gap 66 between the sheave member 20 and the hub member 22 is preferably maintained through the retention of the bearing member 24 relative to the sheave member 20 and through the retention of the bearing member 24 relative to the hub member 22. The retention of the bearing member 24 may be accomplished with several suitable methods.

In the first preferred method, the sheave member 20 is preferably provided with a first sheave retention slot 70 and the retention member 26, preferably provided as a first sheave snap ring 72, is preferably inserted into the first sheave retention slot 70. The first sheave retention slot 70 preferably functions to retain the first sheave snap ring 72 and, in this manner, the first sheave retention slot 70 is preferably annularly shaped and inwardly directed. Additionally, the hub member 22 is preferably provided with a first hub retention slot 74 and a first hub snap ring 76 is preferably inserted into the first hub retention slot 74. The first hub retention slot 74 preferably functions to retain the first hub snap ring 76 and, in this manner, the first hub retention slot 74 is preferably annularly shaped and outwardly directed.

In the first preferred method, the sheave member 20 and the hub member 22 are also preferably provided with a second sheave retention slot 78 and a second hub retention slot 80, respectively, a second sheave snap ring 82 is preferably inserted into the second sheave retention slot 78, and a second hub snap ring 84 is preferably inserted into the second hub retention slot 80. Like the other retention slots, the second sheave retention slot 78 and the second hub retention slot 80 are preferably annularly shaped, while the second sheave retention slot 78 is inwardly directed and the second hub retention slot 80 is outwardly directed. Although the retention member 26 involved in the first preferred method is preferably provided as the first sheave snap ring 72, the second sheave snap ring 82, the first hub snap ring 76, and the second hub snap ring 84, the retention member 26 may alternatively be provided as fewer snap rings. For example, the retention member 26 may alternatively be provided as only the first hub snap ring 76. The first sheave snap ring 72, the second sheave snap ring 82, the first hub snap ring 76, and the second hub snap ring 84 are preferably made from a structural material, such as steel, and with conventional methods, but may alternatively be made from any other suitable material and with any other suitable method.

In the first preferred method, the sheave member 20, the hub member 22, the clutch member 28, and the bearing member 24 are each provided; the hub member 22 is positioned within the sheave member 20; and the clutch member 28 is positioned near the sheave clutch surface 34 and the hub clutch surface 40. At this point, the second sheave snap ring 82 is preferably inserted into the second sheave retention slot 78, and the second hub snap ring 84 is preferably inserted into the second hub retention slot 80. Then, the bearing member 24 is preferably located between the sheave member 20 and the hub member 22 against the second sheave snap ring 82 and the second hub snap ring 84. Finally, the first sheave snap ring 72 and the first hub snap ring 76 are inserted into the first sheave retention slot 70 and the first hub retention slot 74, respectively.

As shown in FIG. 3, in the second preferred method, the sheave member 20' is preferably provided with a sheave mold cavity 86, a mold tool 88 is preferably provided with an outer mold cavity 90 and a polymeric material 92 is preferably molded directly into the sheave mold cavity 86 and the outer mold cavity 90. As shown in FIG. 4, the polymeric material 92, after forming an outer mold ring 94, functions to axially retain the bearing member 24 relative to the sheave member 20'. Additionally, as shown in FIG. 3, the hub member 22' is preferably provided with a hub mold cavity 96, the mold tool 88 is preferably provided with an inner mold cavity 98, and a polymeric material 92 is preferably molded directly into the hub mold cavity 96 and the inner mold cavity 98. As shown in FIG. 4, the polymeric material 92, after forming an inner mold ring 100, functions to axially retain the bearing member 24 relative to the hub member 22'. In the second preferred method, the polymeric material 92 is preferably molded directly into the sheave mold cavity 86 and the hub mold cavity 96 substantially simultaneously. In alternative methods, these acts may be separated by a time period, or by other acts.

In the over-running clutch pulley 10' made with the second preferred method, the bearing member 24 is located adjacent a sheave bearing wall 102 and a hub bearing wall 104. In this manner, the bearing member 24 is axially retained on this side by the sheave member 20' and by the hub member 22'. In alternative methods, the bearing member 24 may be axially retained on this side by other suitable devices and methods, such as another mold ring.

As shown in FIG.s 3 and 4, in the second preferred method, the sheave member 20', the hub member 22', the clutch member 28, and the bearing member 24 are each provided; the hub member 22' is positioned within the sheave member 20'; the clutch member 28 is positioned near the sheave clutch surface 34 and the hub clutch surface 40; and the bearing member 24 is located between the sheave member 20' and the hub member 22'. At this point, the mold tool 88 is partially inserted into the near-assembled pulley 106, the sheave mold cavity 86 and the outer mold cavity 90 are aligned, and the hub mold cavity 96 and the inner mold cavity 98 are aligned. Then, the polymeric material 92 is molded and formed into the outer mold ring 94 and the inner mold ring 100 to axially retain the bearing member 24 relative to the sheave member 20' and the hub member 22'.

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

Claims

CLAIMS We Claim:

1. A method of manufacturing an over-running clutch pulley for rotationally engaging an input device and an output device, comprising: providing a sheave member including a sheave input section and a sheave clutch section defining a sheave clutch surface; and adapting the sheave input section to the engage the input device; providing a hub member including a hub output section and a hub clutch section defining a hub clutch surface; adapting the hub output section to engage the output device; and locating the hub member substantially concentrically within the sheave member; providing a bearing member; and locating the bearing member substantially between the sheave member and the hub member to allow relative rotational movement of the sheave member and the hub member; providing a retention member; and connecting the retention member to one of the sheave member and the hub member to substantially axially retain the bearing member relative to one of the sheave member and the hub member; and providing a clutch member; and adapting the clutch member to engage the sheave clutch surface and the hub clutch surface upon the acceleration of the sheave member in a first rotational direction relative the hub member, and to disengage the sheave clutch surface and the hub clutch surface upon the deceleration of the sheave member in the first rotational direction relative the hub member.

2. The method of Claim 1 further comprising providing the sheave member defining a first sheave retention slot; providing the retention member as a first sheave snap ring; and inserting the first sheave snap ring into the first sheave retention slot to axially retain the bearing member relative to the sheave member.

3. The method of Claim 2 further comprising providing the hub member defining a first hub retention slot; providing a first hub snap ring; and inserting the first hub snap ring into the first hub retention slot to axially retain the bearing member relative to the hub member.

4. The method of Claim 3 further comprising providing the sheave member defining a second sheave retention slot; providing the hub member defining a second hub retention slot; providing a second sheave snap ring; providing a second hub snap ring; inserting the second sheave snap ring into the second sheave retention slot to axially retain the bearing member relative to the sheave member; and inserting the second hub snap ring into the second hub retention slot to axially retain the bearing member relative to the hub member.

5. The method of Claim 4 wherein the act of locating the bearing member occurs after the acts of inserting the second sheave snap ring and inserting the second hub snap ring; and wherein the acts of inserting the first sheave snap ring and inserting the first hub snap ring occur after the act of locating the bearing member.

6. The method of Claim 1 further comprising providing the sheave member defining a sheave mold cavity; providing a mold tool with an outer mold cavity; aligning the sheave mold cavity and the outer mold cavity; and molding a polymeric material directly into the sheave mold cavity and the outer mold cavity, which axially retains the bearing member relative to the sheave member.

7. The method of Claim 6 further comprising providing the hub member defining a hub mold cavity; providing the mold tool with an inner mold cavity; aligning the hub mold cavity and the inner mold cavity; and molding a polymeric material directly into the hub mold cavity and the inner mold cavity, which axially retains the bearing member relative to the hub member.

8. The method of Claim 7 wherein the act the molding the polymeric material directly into the sheave mold cavity and the outer mold cavity and the act of molding the polymeric material directly into the hub mold cavity and the outer mold cavity occur substantially simultaneously.

9. The method of Claim 8 wherein the act of locating the bearing member occurs before the act of molding the polymeric material directly into the sheave mold cavity and the outer mold cavity and the act of molding the polymeric material directly into the hub mold cavity and the outer mold cavity.