CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of U.S. Provisional Application No. 61/423,880, filed on December 16, 2010 and U.S. Provisional Application No. 61/427133, filed on December 24, 2010. The entire disclosure of each of the above applications is incorporated herein by reference.

FIELD

[0002] The present disclosure relates to a clutched driven device.

BACKGROUND

[0003] This section provides background information related to the present disclosure which is not necessarily prior art.

[0004] Many vehicle engine systems include one or more components, commonly referred to as accessories, that are operated with rotary power supplied by an engine. Examples of such components include without limitation alternators, pumps, compressors, superchargers and fans. Typically these components are mounted to the engine and are coupled to the engine crankshaft my means of belt, a chain or a gear train.

[0005] While such components are widely employed, some issues with their operation in a drive system have been identified. For example, such components are commonly configured to operate continuously during operation of the engine. In some cases, however, it may be advantageous to selectively inhibit operation of the component. One such case concerns the operation of a coolant pump or a cooling fan when the engine is relatively cold. It would be desirable, for example, to inhibit operation of the coolant pump or the cooling fan in such situations to permit the engine to heat more rapidly to a desired operating temperature.

[0006] International Patent Application Publication Number WO 2010/054487 discloses several components having a clutch assembly that permits selective operation of the component during the operation of an engine. We have noted, however, that while WO 2010/054487 discloses several highly robust clutching systems, there can be instances where these clutching systems are difficult to package into a component. One exemplary situation involves the integration of a clutching system into a vehicle component that is currently in production. Accordingly, there remains a need in the art for a driven, clutched component having a relatively compact clutching system. SUMMARY

[0007] This section provides a general summary of the disclosure, and is not a comprehensive disclosure of its full scope or all of its features.

[0008] In one form, the present disclosure provides a clutched, driven component that includes a clutch assembly with a driven member, a driver, a carrier, a wrap spring, a retainer, and an actuator. The driven member has a clutch surface and is configured to be coupled to a source of rotary power. The carrier abuts the driver. The wrap spring is coiled on the carrier and includes a plurality of helical coils, a tang and an engaging portion. The tang extends from a first axial end of the wrap spring. The engaging portion is disposed on a second, opposite axial end of the wrap spring. The engaging portion extends over less than one helical coil and contacts the driver. The actuator is operable for selectively causing at least a portion of the helical coils to engage or disengage the clutch surface. The driver includes a driver tab that contacts an axial end face of the engaging portion of the wrap spring. The retainer includes a retainer tab that abuts the driver tab.

[0009] In another form the present disclosure provides a clutched, driven component that includes a clutch assembly with a driven member, a driver, a carrier, a wrap spring, a retainer, and an actuator. The driven member has a clutch surface and is configured to be coupled to a source of rotary power. The carrier abuts the driver. The wrap spring is coiled on the carrier and includes a plurality of helical coils, a tang and an engaging portion. The tang extends from a first axial end of the wrap spring. The engaging portion is disposed on a second, opposite axial end of the wrap spring. The engaging portion extends over less than one helical coil and contacts the driver. The actuator is operable for selectively causing at least a portion of the helical coils to engage or disengage the clutch surface. The retainer is assembled to the driver and fixed thereto in an axial direction. The carrier and the wrap spring are disposed between the retainer and the driver.

[0010] Further areas of applicability will become apparent from the description provided herein. The description and specific examples in this summary are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure.

DRAWI NGS

[0011] The drawings described herein are for illustrative purposes only of selected embodiments and not all possible implementations, and are not intended to limit the scope of the present disclosure.

[0012] Figure 1 is an exploded perspective view of a clutched, driven component constructed in accordance with the teachings of the present disclosure;

[0013] Figures 2 and 3 are exploded perspective views of a portion of the clutched, driven device of Figure 1 , illustrating a driver in more detail;

[0014] Figure 4 is an exploded perspective view of a portion of the clutched, driven device of Figure 1 , illustrating the driver, a carrier, a wrap spring and a retainer in more detail;

[0015] Figure 5 is a front elevation view of a portion of the clutched, driven device of Figure 1 , illustrating an end of the wrap spring abutting a driver tab on the driver and a retaining tab on the retainer supporting the driver tab;

[0016] Figure 6 is a perspective view of the carrier;

[0017] Figure 7 is an exploded perspective view of a portion of the clutched, driven device of Figure 1 , illustrating a sheave spacer, a bearing, the driver, the carrier, the wrap spring and the retainer in more detail;

[0018] Figure 8 is a perspective view of an alternately constructed driver having lightening holes; and

[0019] Figure 9 is an exploded perspective view of a second clutched, driven component constructed in accordance with the teachings of the present disclosure.

[0020] Corresponding reference numerals indicate corresponding parts throughout the several views of the drawings.

DETAILED DESCRIPTION

[0021] Example embodiments will now be described more fully with reference to the accompanying drawings.

[0022] Referring to Figure 1 , a clutched driven device constructed in accordance with the teachings of the present disclosure is generally indicated by reference numeral 300. The clutched driven device 300 has reduced cost and improved performance as compared to some clutch assemblies of the prior art. The clutched driven device 300 can include a driver 1 having a hub 302 that can be tubular in shape and can fixedly connect an input shaft (not shown) of driven component, such as a water pump (not shown). The connection may be of any suitable means, such as an interference fit, threads, splines, and/or a key, for example.

[0023] The hub 302 can have an outside surface 303 that can support a bearing 304, which in turn can rotatably support a sheave spacer 306, which in turn has a sheave (not shown) mounted thereto. It will be appreciated that the sheave spacer 306 and the sheave can be unitarily formed in the alternative.

[0024] The clutched, driven device 300 can further include an outer member 310 that can be fixedly mounted to the hub 302. The outer member 310 can be made from a material that is of lower strength than the material from which the hub 302 is formed so as to reduce the cost of manufacture of the driver 1. The lower strength may be achieved by making the outer member 310 from a thinner-walled material than that of the hub 302. Alternatively or additionally, the material of the outer member 310 may be selected to be a weaker material, such as a weaker grade of steel than that selected for the hub 302. It will be understood that the material used for the outer member 310 may be a stronger material (e.g. , a stronger grade of steel) than that of the hub 302. However, because of the reduced strength requirements for the outer member 310 as compared with analogous portions of previously known drivers, the outer member 310 could be made with thinner walls than previous drivers. Thus, it is not necessary for the purposes of the invention described and claimed herein for the outer member to be made from a different material (e.g. , a weaker material) as the hub 302.

[0025] The connection between the outer member 310 and the hub 302 may be by any suitable means. For example, referring to Figures 2 and 3, the hub 302 may be provided with a non-circular end 312 (e.g., polygonal shaped, such as hex- shaped), which can pass through and engage a complementarily shaped aperture 314 (e.g. , a hex-shaped aperture) in the outer member 310, and the two components 302 and 310 may be staked together. Other means may alternatively be used to connect the hub 302 and the outer member 310 to each other, such as, for example, a press fitting, welding (e.g. , laser welding, friction welding). It will be noted that the hub 302 may be manufactured to relatively tight tolerances on its radially outer surface 303, and on its radially inner surface shown at 315 which connects to the driven component (not shown). More specifically, the hub 302 can be manufactured such that the radially outer surface 303 and the radially inner surface 315 are concentric within 0.005 inch (0.13 mm), while the hub 302 can be coupled to the outer member 310 such that a radially outer surface of the outer member can be concentric with the radially inner surface 315 of the hub 302 within 0.02 inch (0.5 mm). Achieving the tolerances on the radially inner surface 315 and the radially outer surface 303 may be difficult for analogous components that are unitarily formed (i.e., manufactured from a single piece of material). By manufacturing the driver 1 from a hub 302 and a separate outer member 310, the hub 302 can be machined as necessary to provide the desired tolerances, after which point, the outer member 310 may be connected thereto.

[0026] With reference to Figures 1 , 4 and 5, the outer member 310 can have a driver tab 316 thereon that can extend radially outwardly. In the particular example provided, the outer member 310 has a plurality of driver tabs 316, spaced apart at 120 degrees from each other, but it will be appreciated that the driver 1 could be configured with a single driver tab 316. The driver tab 316 can be engaged on a first side by a first end 9 of a wrap or wrap spring 3, and on a second side by a retainer tab 317 that can be provided on a retainer 2. The driver tab 316 can be oriented axially along the rotational axis of the driver 1 so as to provide a suitable surface area for engagement by an axial end face of the end 9 of the wrap spring 3. The retainer tab 317, however, can be oriented circumferentially so as to strengthen the tab 316 against deformation when a circumferential force is applied to the driver tab 316 by the axial end face of the end 9 of the wrap spring 3. In this regard, the retainer tab 317 can have a radially extending face that can directly abut a corresponding radially extending face of the driver tab 316.

[0027] It will be noted that the tabs 316 and 3 7 are both easily formed on the driver 1 and retainer 2 respectively by simple stamping and bending operations on relatively lightweight metal, while providing good resistance to deformation from circumferential forces exerted by the end 9 of the wrap spring 3. For example, the tab 316 may be formed by bending a portion of the outer member 310 radially outwards, and the tab 317 may be formed by bending a portion of the retainer 2 radially outwards. In the particular example provided, the retainer tab 317 is received in and fills a gap G (best shown in Fig. 7) formed in the outer member 310 between the driver tab 316 and a circumferentially-opposite edge E (best shown in Fig. 7).

[0028] With reference to Figures 1 , 4, and 6, the end 9 of the wrap spring 3 can be held in a groove 318 (Fig. 4) in a carrier 4. The wrap spring 3 can be wrapped on the carrier 4 and the carrier 4 can be fit over the outer cylindrical surface 14 of the outer member 310 of the driver 1 such that the first end 9 of the wrap spring 3 abuts the driver tab 316.

[0029] With reference to Figure 7, the carrier 4 can be axially abutted against a flange portion 319 on the outer member 3 0. The carrier 4 may be made from any desired material, for example a polymeric material, such as, a high-grade, glass-filled plastic, such as nylon 4-6. The carrier 4 can have a shoulder 320 (best seen in Fig. 4) that axially abuts the wrap spring 3. The carrier 4 can be sized in length such that it supports the entire axial length of the wrap spring 3 and as such, the outer cylindrical surface 14 of the outer member 310 need not be sized in an axial direction so that it supports the entire axial length of the wrap spring 3. As a result, the driver 1 may be lighter than some other drivers from other clutch assemblies that have to support a portion of the wrap spring 3. Additionally, by lengthening the carrier 4 as compared to some other carriers in other assemblies, the carrier 4 is relatively stronger.

[0030] Referring to Figures 4 and 7, the retainer 2 can include an outer cylindrical surface 322 that can be received in an inner cylindrical surface 324 in the carrier 4. The retainer 2 further can include a flange 326 that can abut an axial end 328 of the carrier 4 on a side opposite the flange portion 319 of the outer member 310 to thereby axially capture the wrap spring 3 between the shoulder 320 on the carrier 4 and by the flange portion 326 on the retainer 2. A gap 330 in the flange 326 can expose the second end 332 (Fig. 7) of the wrap spring 3.

[0031] With reference to Figures 1 and 7, the second end 332 of the wrap spring 3 can be configured to engage a first clutch member 336. In the particular example provided, the first clutch member 336 includes a fork 334 that engages the second end 332 of the wrap spring 3. The first clutch member 336 can also comprise a teaser member 340 that can be engaged to a teasing surface 342 on the sheave spacer 306. The first clutch member 336 can be movable axially between a first position, in which the teaser member 340 engages the surface 342 on the sheave spacer 306, and a second position in which the teaser member 340 is disengaged from the sheave spacer 306. The first clutch member 336 can be biased towards the first position by any suitable means, such as a leaf spring LS that can be coupled to the hub 302 for rotation therewith. Any suitable mechanism can be employed to selectively move the first clutch member 336 from the first position to the second position. Suitable mechanisms are shown and described in PCT publication W02010/054487A1 , the contents of which are incorporated herein by reference.

[0032] During operation of the clutched, driven device 300 when the clutch member 336 is positioned in the first position, rotation of the sheave (not shown) drives the rotation of the sheave spacer 306, which, due to the frictional engagement with the teaser member 340, initiates rotation of the first clutch member 336. Because the first clutch member 336 is engaged with the second end 332 of the wrap spring 3, the first clutch member 336 drives the second end 332 to rotate. The first end 9 of the wrap spring 3 resists rotation, however, due to inertia associated with the load that exists on the driven component (e.g., a water pump) that is driven by the driver . The resistance to rotation of the first end 9 combined with the rotation that occurs in the second end 332 causes the wrap spring 3 to expand radially, so that its radially outer surface 343 engages an inner cylindrical surface 344 of the sheave spacer 306. This engagement more positively connects the sheave spacer 306 (and therefore the sheave (not shown)) to the wrap spring 3 so that the rotation of the sheave spacer 306 drives the rotation of the second end 9 of the wrap spring 3, which in turn drives the driver 1 to rotate, which in turn drives the driven component (e.g. , water pump) to rotate.

[0033] The retainer 2 may be fixedly connected to the driver 1 to prevent axial movement of the retainer 2 out of its intended position. The connection may be by any suitable means. For example, the retainer 2 may include axially extending tabs 346 that can engage the driver 1 . In the example provided, the axially extending tabs 346 are configured to pass through axial slots S in the carrier 3 and through tab receiving apertures 348 in the flange portion 3 9 of the outer member 310. The tabs 346 may be bent (e.g., radially inwardly or outwardly) or twisted so as to prevent the retainer 2 from being withdrawn from the driver 1. Alternatively, the tabs 346 could be configured to snap fit with the flange 319 after passing through the apertures 348. The retainer 2 can include a second end flange 350 that can capture the first end 9 of the wrap spring 3 in the groove 318 in the carrier 4. [0034] The driven, clutched device 300 can provide several advantages. One advantage is that the driven, clutched device 300 can be lighter than some other driven, clutched devices, due in part to providing an outer member 310 that is thinner walled or that is a lower density material than some analogous portions of other drivers, which would use a relatively thick walled material so as to increase the strength of any tab that is engaged the wrap spring. This reduced weight can translate into a capability of the present driven, clutched device 300 to handle more torque than some other driven, clutched devices. Furthermore, the reduced weight can translate into an increased service life for the driven, clutched device 300. This is because the stopping and starting of the driver 1 may have less resistance associated with it than stopping and starting a heavier driver that has correspondingly greater inertia. This reduced resistance culminates in less stress on the wrap spring 3 than in a driven, clutched device with a heavier driver which has greater inertia.

[0035] Optionally, the driver 1 may further include other weight reducing features, such as lightening holes shown at 400 in Figure 8, which would be provided in the outer member 310 at selected locations. The lightening holes 400 can be positioned in selected positions to account for any rotational imbalances that may be present in the driven, clutched device 300 (Fig. 1 ). Furthermore, it is possible that the lightening holes 400 can be placed in strategic locations so as to permit the flow of lubricant to selected portions of the assembly as needed during use of the assembly after it has been stored for long periods of time, especially if it has been stored in a position that would raise the potential for any lubrication therein to settle in a place that is removed from the places the lubricant is normally located during use.

[0036] The example of Figure 9 is generally similar to the previously described example, except that a driver 600 is substituted for the driver 1 (Fig. 1 ). The driver 600 can be a one-piece (i.e., unitarily formed) driver and can be configured to hold the wrap spring 3 and a carrier 604. The driver 600 can include an abutment surface 602 thereon for engagement by the axial end face of the end 9 of the wrap spring 3. The abutment surface 602 can be machined or molded or otherwise formed in a like operation on the driver 600. The combination of the driver 600 and carrier 604 may be heavier than the combination of the driver 1 , the retainer 2 and the carrier 4 of Figure 1. [0037] The foregoing description of the embodiments has been provided for purposes of illustration and description. It is not intended to be exhaustive or to limit the disclosure. Individual elements or features of a particular embodiment are generally not limited to that particular embodiment, but, where applicable, are interchangeable and can be used in a selected embodiment, even if not specifically shown or described. The same may also be varied in many ways. Such variations are not to be regarded as a departure from the disclosure, and all such modifications are intended to be included within the scope of the disclosure. Listing of Elements

driver 1 inner cylindrical surface 324 retainer 2 flange 326 wrap spring 3 axial end 328 carrier 4 gap 330 first end 9 second end 332 outer cylindrical surface 14 fork 334 clutched driven device 300 first clutch member 336 hub 302 teaser member 340 outside surface 303 teasing surface 342 bearing 304 radially outer surface 343 shave spacer 306 tabs 346 outer member 310 tab receiving apertures 348 non-circular end 312 second end flange 350 complementary shaped aperture314 holes 400 radially inner surface 315 driver 600 driver tab 316 abutment surface 602 retainer tab 317 carrier 604 groove 318 edge E flange portion 319 gap G shoulder 230 leaf spring LS outer cylindrical surface 322 axial slots S