WO2017044988A1

WO2017044988A1 - Accessory operable in electrically-driven and mechanically-driven modes having and clutch for selectively coupling mechanical drive element to output shaft and actuator for coordinating operation of clutch

Info

Publication number: WO2017044988A1
Application number: PCT/US2016/051434
Authority: WO
Inventors: James E. Ignatovich; David Vanzuilen; Wolfgang Sorg; Jason Mcdonald; Daniel Haertel; Stephen BOHAN
Original assignee: Borgwarner Inc.
Priority date: 2015-09-13
Filing date: 2016-09-13
Publication date: 2017-03-16

Abstract

An accessory having a drive housing, drive element, an output shaft, an electric motor, a clutch and an actuator. The drive element is disposed for rotation about a rotary axis. The output shaft is received in the housing and disposed for rotation about the rotary axis. The electric motor is received in a cavity in the drive housing and has a stator, which is fixed to the drive housing, and a rotor that is drivingly coupled to the output shaft. The clutch is operable in pair of operational modes that include a first mode, in which rotary power is transmitted between the drive element and the output shaft, and a second mode in which rotary power is not transmitted between the drive element and the output shaft. The actuator is configured to selectively move a portion of the clutch along the rotary axis to change the operational mode of the clutch.

Description

ACCESSORY OPERABLE IN ELECTRICALLY-DRIVEN AND

MECHANICALLY-DRIVEN MODES HAVING AND CLUTCH FOR SELECTIVELY COUPLING MECHANICAL DRIVE ELEMENT TO OUTPUT SHAFT AND ACTUATOR FOR COORDINATING OPERATION OF CLUTCH CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of U.S. Provisional Application No. 62/217,881 , filed on September 13, 2015, U.S. Provisional Application No. 62/238,076, filed on October 6, 2015 and U.S. Provisional Application No. 62/280,680, filed on January 19, 2016. The entire disclosure of each of the above applications is incorporated by reference as if fully set forth in detail herein.

FIELD

[0002] The present disclosure relates to engine-driven accessories, and more particularly to an accessory that is operable in electrically-driven and mechanically-driven modes. The accessory has a clutch for selectively coupling a mechanical drive element to an output shaft, and an actuator for coordinating operation of the clutch.

BACKGROUND

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

[0004] Engine accessories, such as coolant pumps, cooling fans, viscous heaters, and air conditioning compressors, are in use today with virtually all types of engines. There have been many attempts to provide improved engine accessories, particularly those which have improved efficiency, improved performance, are more easily packaged into an engine, and/or that are less costly.

SUMMARY

[0005] This section provides a general summary of the disclosure, and is not a comprehensive disclosure of its full scope or all of its features. [0006] In one form, the present disclosure provides an accessory having a drive housing, drive element, an output shaft, an electric motor, a clutch and an actuator. The drive element is disposed for rotation about a rotary axis. The output shaft is received in the housing and disposed for rotation about the rotary axis. The electric motor is received in a cavity in the drive housing and has a stator, which is fixed to the drive housing, and a rotor that is drivingly coupled to the output shaft. The clutch is operable in pair of operational modes that include a first mode, in which rotary power is transmitted between the drive element and the output shaft, and a second mode in which rotary power is not transmitted between the drive element and the output shaft. The actuator is configured to selectively move a portion of the clutch along the rotary axis to change the operational mode of the clutch.

[0007] In another form, the present disclosure provides method for operating an accessory that has a drive element, a rotary electric motor, an output shaft and a clutch. The rotary electric motor has a stator and a rotor. The rotor is non-rotatably but axially slidably coupled to the output shaft. The clutch is operable in a first state, in which the clutch is configured to transmit rotary power between the drive element and the output shaft, and a second state in which the clutch is configured to decouple the drive element from the output shaft. The method includes: rotating the drive element while not operating the electric motor to transmit rotary power from the drive element through the clutch to the output shaft; and operating the electric motor to apply a magnetically-generated force to the rotor and to rotate the output shaft, wherein the magnetically-generated force has a magnitude that shifts the rotor along the rotary axis so that the clutch operates in the second state.

[0008] 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. DRAWINGS

[0009] 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.

[0010] Figure 1 is a longitudinal cross-section view of a first accessory constructed in accordance with the teachings of the present disclosure;

[0011] Figure 2 is a perspective, partly sectioned view of the accessory of Figure 1 ;

[0012] Figure 3 is a perspective, partly sectioned view of a second accessory constructed in accordance with the teachings of the present disclosure;

[0013] Figures 4 and 5 are portions of longitudinal section views of the accessory of Figure 3 that depict a clutch of the accessory in engaged and disengaged conditions, respectively;

[0014] Figure 6 is a longitudinal section view of a third accessory constructed in accordance with the teachings of the present disclosure;

[0015] Figure 7 is an exploded longitudinal section view of the accessory of Figure 6;

[0016] Figure 8 is an enlarged portion of Figure 6;

[0017] Figure 9 is a perspective longitudinal section view of a portion of the accessory of Figure 6 that depicts a solenoid in more detail; and

[0018] Figures 10 through 12 are schematic illustrations of differently configured actuators for the accessories of Figures 1 and 3.

[0019] Corresponding reference numerals indicate corresponding parts throughout the several views of the drawings.

DETAILED DESCRIPTION

[0020] Example embodiments are provided so that this disclosure will be thorough, and will fully convey the scope to those who are skilled in the art. Numerous specific details are set forth such as examples of specific components, devices, and methods, to provide a thorough understanding of embodiments of the present disclosure. It will be apparent to those skilled in the art that specific details need not be employed, that example embodiments may be embodied in many different forms and that neither should be construed to limit the scope of the disclosure. In some example embodiments, well-known processes, well-known device structures, and well-known technologies are not described in detail.

[0021] The terminology used herein is for the purpose of describing particular example embodiments only and is not intended to be limiting. As used herein, the singular forms "a," "an," and "the" may be intended to include the plural forms as well, unless the context clearly indicates otherwise. The terms "comprises," "comprising," "including," and "having," are inclusive and therefore specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. The method steps, processes, and operations described herein are not to be construed as necessarily requiring their performance in the particular order discussed or illustrated, unless specifically identified as an order of performance. It is also to be understood that additional or alternative steps may be employed.

[0022] When an element or layer is referred to as being "on," "engaged to," "connected to," or "coupled to" another element or layer, it may be directly on, engaged, connected or coupled to the other element or layer, or intervening elements or layers may be present. In contrast, when an element is referred to as being "directly on," "directly engaged to," "directly connected to," or "directly coupled to" another element or layer, there may be no intervening elements or layers present. Other words used to describe the relationship between elements should be interpreted in a like fashion (e.g., "between" versus "directly between," "adjacent" versus "directly adjacent," etc.). As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed items.

[0023] Although the terms first, second, third, etc. may be used herein to describe various elements, components, regions, layers and/or sections, these elements, components, regions, layers and/or sections should not be limited by these terms. These terms may be only used to distinguish one element, component, region, layer or section from another region, layer or section. Terms such as "first," "second," and other numerical terms when used herein do not imply a sequence or order unless clearly indicated by the context. Thus, a first element, component, region, layer or section discussed below could be termed a second element, component, region, layer or section without departing from the teachings of the example embodiments.

[0024] Spatially relative terms, such as "inner," "outer," "beneath," "below," "lower," "above," "upper," and the like, may be used herein for ease of description to describe one element or feature's relationship to another element(s) or feature(s) as illustrated in the figures. Spatially relative terms may be intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if the device in the figures is turned over, elements described as "below" or "beneath" other elements or features would then be oriented "above" the other elements or features. Thus, the example term "below" can encompass both an orientation of above and below. The device may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein interpreted accordingly.

[0025] With reference to Figures 1 and 2 of the drawings, an exemplary engine-driven accessory constructed in accordance with the teachings of the present disclosure is generally indicated by reference numeral 10. The accessory 10 in the particular example provided is a coolant pump, but those of skill in the art will appreciate that the accessory 10 could be another type of engine accessory, such as a viscous heater, a fan drive, an oil pump, a transmission fluid pump, or an air conditioning compressor.

[0026] The accessory 10 can include a drive portion 12 and an accessory portion 14 that can receive rotary power from the drive portion 12. The drive portion 12 can include a drive housing 16, an output shaft 18, a drive element 20, an electric motor 22 and a clutch 24, while the accessory portion 14 can include an accessory housing 30, an accessory input shaft 32 and optionally, an accessory work element 34. In the example provided, the accessory portion 14 is a coolant pump and the accessory work element 34 is an impeller.

[0027] The accessory housing 30 can be fixedly coupled to the drive housing 16 and can define a cavity 40 into which the electric motor 22 can be received. If desired, the accessory housing 30 and the drive housing 16 could be unitarily and integrally formed.

[0028] The output shaft 18 can extend through the drive housing 16 and can include a first bearing mount 42, a second bearing mount 44, rotor mount 46, a spring flange 48 and an output portion 50. A first bearing 52 can be received on the first bearing mount 42 and can be employed to support the output shaft 18 for rotation about a rotary axis 54 relative to the accessory housing 30, while a second bearing 56 can be received on the second bearing mount 44 and can be employed to support the drive element 20 for rotation about the output shaft 18. The spring flange 48 can be disposed axially between the rotor mount 46 and the output portion 50 and can comprise an annular shoulder or disk-like projection that can be formed on the output shaft 18. The output portion 50 can be coupled to the accessory input shaft 32 for common rotation. In the example provided, the output portion 50 is press-fit to the accessory input shaft 32, but it will be appreciated that the accessory input shaft 32 could be threadably coupled to the output portion 50 of the output shaft 18 or could be axially slidably but non-rotatably coupled to the output portion 50 of the output shaft 18. If desired, the accessory input shaft 32 could be unitarily and integrally formed with the output shaft 18.

[0029] The drive element 20 can be any type of structure that is configured to transmit rotary power, such as a gear (not shown) or a sprocket (not shown). In the particular example provided, the drive element 20 comprises a pulley that is configured to engage a belt of a front engine accessory drive (not shown).

[0030] The electric motor 22 can be any suitable type of motor, such as a reluctance or switched reluctance motor. In the particular example provided, the electric motor 22 is an AC induction motor, and can include a stator 60, a rotor 62 and a motor controller 64. The stator 60 can be fixedly coupled to the drive housing 16 and can include a plurality of coils of insulated wire or windings 66 that can be disposed axially along the rotary axis 54 about a nominal longitudinal centerline 68. The windings 66 can define a plurality of stator poles 70 that can be disposed circumferentially about the rotary axis 54. The stator poles 70 can be disposed along the rotary axis 54 at a nominal location that is depicted by reference numeral 68 (i.e., the longitudinal center line of the windings 66).

[0031] The rotor 62 can include a rotor body 80 and a plurality of rotor bars 82. The rotor body 80 can be non-rotatably but axially slidably mounted to the rotor mount 46 on the output shaft 18. For example, the rotor body 80 can define a mount portion 90, a rim portion 92 and a connector portion 94 that extends radially between and fixedly couples the mount portion 90 to the rim portion 92. The mount portion 90 can define a central aperture 96 into which the rotor mount 46 can be slidably received. In the example provided, the central aperture 96 defines a set of female spline teeth that are matingly engaged by a set of male spline teeth 100 that are formed on the rotor mount 46. The rim portion 92 can define a plurality of bar mounts 102 that are configured to receive a corresponding one of the rotor bars 82. In the example provided, the rotor bars 82 are cylindrically shaped structures that are received in holes formed through the rim portion 92 parallel to the rotary axis 54 such that the rotor bars 82 extend parallel to the rotary axis 54 and are spaced circumferentially about the rotary axis 54. It will be appreciated, however, that the rotor bars 82 can be shaped and/or oriented (e.g., skewed relative to the rotary axis 54) differently from that which is shown here and can be fixedly coupled to the rim portion 92 in any desired manner, including press-fitting, bonding, or overmolding the rotor bars 82 in a material that forms the rotor body 80. The rotor 62 can define a plurality of rotor poles 1 10 that can be disposed along the rotary axis 54 at a nominal location that is depicted by reference numeral 1 18.

[0032] The motor controller 64 can be configured in a conventional manner to control transmission electrical power through the windings 66 to thereby control rotation of a magnetic field produced by the windings 66. In the example provided, the motor controller 64 comprises a printed circuit board that is housed in the drive housing 16. It will be appreciated, however, that all or portions of the motor controller 64 could be housed separately from the stator 60 and the rotor 62.

[0033] The clutch 24 can be any type of axially-operated clutch that can be operated to selectively transmit rotary power from the drive member - to the output shaft 18, such as a dog clutch, a friction clutch (e.g., a friction clutch with a multi-plate clutch pack, a clutch having two flat friction surfaces that can be selectively engaged to one another, a cone clutch), or a clutch that employes a toothed sliding sleeve. In the example provided, the clutch 24 is a ratchet clutch and includes a clutch input member 120, a clutch output member 122 and a biasing spring 124. The clutch input member 120 can be an annular structure that can be coupled to the drive element 20 for rotation therewith and can have a first set of ratchet teeth 130 that can be disposed circumferentially about the rotary axis 54. The clutch output member 122 can be an annular structure that can be coupled to the output shaft 18 for common rotation. In the example provided, the clutch output member 122 is fixedly coupled to the rotor 62 and includes a second set of ratchet teeth 132 that can be disposed circumferentially about the rotary axis 54. The biasing spring 124 can bias the rotor 62 and the clutch output member 122 toward the clutch input member 120 so that the second set of ratchet teeth 132 engage the first set of ratchet teeth 130. In the particular example provided, the biasing spring 124 is a helical coil spring that is disposed axially between (and in abutment with) an axial end of the rotor 62 and the spring flange 48 that is formed on the output shaft 18, but it will be appreciated that any type of spring could be employed. Moreover, other devices, such as opposing magnets, could be substituted for the biasing spring 124.

[0034] It will be appreciated that the biasing spring 124 will normally urge the rotor 62 and the clutch output member 122 toward the clutch input member 120 so that the nominal location 1 18 of the rotor poles 1 10 is offset axially along the rotary axis 54 from the nominal location 68 of the stator poles 70.

[0035] The accessory 10 can be operated mechanically, in which rotary power to drive the output shaft 18 is provided exclusively via the drive pulley -, or electrically in which rotary power to drive the output shaft 18 is provided exclusively via the electric motor 22.

[0036] Mechanical operation of the accessory 10 entails the provision of rotary power to the drive element 20 to drive the output shaft 18 of the drive portion 12 to thereby drive the accessory input shaft 32 (and if included, the accessory work element 34). In the example provided, a belt is disposed in engagement with the drive element 20 such that drive element 20 is rotated by the belt. Because the clutch input member 120 is coupled to the drive element 20 for common rotation, rotation of the drive element 20 causes corresponding rotation of the clutch input member 120.

[0037] In the mechanically operated mode, the electric motor 22 is not powered and as such, the force generated by the biasing spring 124 is sufficient to drive the rotor 62 toward the clutch input member 120 so that the clutch output member 122 drivingly engages the clutch input member 120. It will be appreciated that rotary power received by the clutch input member 120 drives the output shaft 18, and therefore the rotor 62, the accessory input shaft 32 and the accessory work element 34. If desired, back emf produced when the rotor 62 is driven in this mode could be employed as a source of electrical power (e.g., for charging a battery of a vehicle).

[0038] Electrical operation of the accessory 10 entails the operation of the electric motor 22 to produce rotary power that directly drives the output shaft 18 and the decoupling of the clutch output member 122 from the clutch input member 120 so that the output shaft 18 is driven independently of the drive element 20. The motor controller 64 conventionally coordinates the transmission of electrical power to the windings 66 to generate a first magnetic field that induces current flow in the rotor 62 so that a second magnetic field is generated. Typically, the first and second magnetic fields are employed to cause rotation of the rotor 62 relative to the stator 60. Since the nominal location 1 18 of the rotor poles 1 10 is offset axially along the rotary axis 54 from the nominal location 68 of the stator poles 70, the first and second magnetic fields are axially offset from one another when electrical energy is initially provided to the windings 66. Consequently, the first and second magnetic fields cooperate to apply a magnetically-generated force to the rotor 62 that overcomes the force of the biasing spring 124 and causes the rotor 62 to shift or translate along the rotary axis 54 such that the nominal location 1 18 of the rotor poles 1 10 is aligned or coincident with the nominal location 68 of the stator poles 70 to thereby axially align the first and second magnetic fields. It will be appreciated that the clutch output member 122 is fixed to the rotor 62 and as such, this movement of the rotor 62 will cause corresponding disengagement of the clutch output member 122 from the clutch input member 120. It will be appreciated that rotary power output from rotor 62 will drive the output shaft 18 and therefore the accessory input shaft 32 and the accessory work element 34.

[0039] With reference to Figures 3 through 5, a second accessory constructed in accordance with the teachings of the present disclosure is generally indicated by reference numeral 10a. The accessory 10a is generally similar to that of Figures 1 and 2, except for the configuration of the output shaft 18a, the rotor 62a and the clutch 24a.

[0040] The output shaft 18a is formed as two components - a main shaft portion 200 and a sleeve 202 that is coupled to the main shaft portion 200 for common rotation. In the example provided, the spring flange 48a and the rotor mount 46a are formed on the sleeve 202, and the biasing spring 124a is received on the sleeve 202 between the spring flange 48a and the rotor mount 46a.

[0041] With reference to Figure 4, the clutch 24a can include a clutch spring 210, a first clutch surface 212, a second clutch surface 214, a carrier 216, and a friction element 218. The clutch spring 210 can be a type of helical coil spring that can be formed of wire, such as wire having a round, square or rectangular cross-sectional shape, and can have a plurality of input coils 220 and a plurality of output coils 222. Optionally, the clutch spring 210 can have a tang 224 on one or more of its ends.

[0042] The first clutch surface 212 can be coupled for rotation with the drive element 20, while the second clutch surface 214 can be coupled to the rotor 62a for rotation therewith. In the example provided, the first clutch surface 212 is a cylindrical surface that is formed by a bore 226 in the drive element 20. The bore 226 can be sized to the diameter of the input coils 220 so that there is a desired degree of "fit" between the outer diameter of the input coils 220 and the first clutch surface 212. For example, the outer diameter of the input coils 220 can be sized to engage the first clutch surface 212 when the input coils 220 are received into the bore 226. If a tang 224 is employed on the input side of the clutch spring 210, the tang 224 can be received into a tang bore 226 formed in the drive element 20.

[0043] Similarly, the second clutch surface 214 can be coupled to the rotor 62a for rotation therewith. In the example provided, the second clutch surface 214 is a cylindrical surface that is formed by a bore 234 in the rotor 62a. The bore 234 can be sized to the diameter of the output coils 222 so that there is a desired degree of "fit" between the outer diameter of the output coils 222 and the second clutch surface 214. In the example provided, the outer diameter of the output coils 222 is somewhat smaller than the inside diameter of the second clutch surface 214 so that the rotor 62a and the output coils 222 are ordinarily able to rotate about the rotary axis 54 relative to one another.

[0044] The carrier 216 can be a sleeve-like structure that can be received about the output shaft 18a radially between the first bearing 52 and the output coils 222 of the clutch spring 210. If a tang is employed on the output side of the clutch spring 210, the tang can be received into a tang bore formed in the carrier 216. It will be appreciated that while the first bearing 52 is depicted as being a needle bearing, the first bearing 52 could be any type of bearing or bushing. The carrier 216 is rotatable about the output shaft 18a and can translate on the output shaft 18a between a first position, which is depicted in Figure 4, and a second position that is depicted in Figure 5.

[0045] The friction element 218 can be fixedly coupled to the output shaft 18a. In the example provided, the friction element 218 is a cap-like structure that is received over the output shaft 18a.

[0046] Mechanical operation of the accessory 10a entails the provision of rotary power to the drive element 20 to drive the output shaft 18a of the drive portion 12 (Fig. 3) to thereby drive the accessory input shaft 32 (and if included, the accessory work element 34). In the example provided, a belt (not shown) is disposed in engagement with the drive element 20 such that drive element 20 is rotated by the belt. Because the clutch input member (i.e., the input coils 220 of the clutch spring 210) is coupled to the drive element 20 for common rotation, rotation of the drive element 20 causes corresponding rotation of the input coils 220 (i.e., the clutch input member) of the clutch spring 210.

[0047] In the mechanically operated mode, the electric motor 22 is not powered and as such, the force generated by the biasing spring 124 is sufficient to drive the rotor 62a along the rotary axis 54 toward the drive element 20 so that the carrier 216 is brought into frictional engagement with the friction element 218 on the output shaft 18a. Rotation of the drive element 20 causes corresponding rotation of the input coils 220, which causes corresponding rotation of the output coils 222 and the carrier 216. Since the carrier 216 is frictionally engaged to the friction element 218, and since the friction element 218 is coupled to the output shaft 18a for common rotation, rotation of the carrier 216 will tend to rotate the output shaft 18a. Rotational drag on the output shaft 18a, which may be due in part to the torque that is required to rotate the accessory work element 34, resists or slows rotation of the carrier 216 relative to the drive element 20, which causes the output coils 222 to unwind and drivingly engage the second clutch surface 214 to thereby transmit rotary power to the output shaft 18a via the rotor 62a. It will be appreciated that the wire of the clutch spring 210 is wound so that rotation of the drive element 20 in a predetermined rotational direction works to unwind the input coils 220 so that they engage (or more securely engage) the first clutch surface 212.

[0048] With reference to Figure 5, electrical operation of the accessory 10a entails the operation of the electric motor 22 to produce rotary power that directly drives the output shaft 18a and the decoupling of the output coils 222 (i.e., the clutch output member) from the second clutch surface 214 so that the output shaft 18a is driven independently of the drive element 20. In a manner identical to that of the previous embodiment, the provision of electrical power to the windings 66 of the electric motor 22 generates magnetic fields that create a magnetically-generated force that causes the rotor 62a to shift or translate along the rotary axis 54 against the force of the biasing spring 124 so that the nominal location of the rotor poles is more fully aligned (and preferably coincident) with the nominal location of the stator poles to thereby axially align the magnetic fields. It will be appreciated that the axial shifting of the rotor 62a (i.e., away from the drive element 20) permits the clutch spring 210 to urge the carrier 216 axially along the rotary axis so that the carrier 216 is axially spaced apart from (and thereby disengaged from) the friction element 218. Consequently, no or very little drag force is exerted onto the carrier 216 and output coils 222 so that the output coils 222 essentially rotate at the same speed as the drive element 20. In this condition, the output coils 222 assume their normal shape so that the rotor 62 and second clutch surface 214 are rotatable relative to the output coils 222 and the carrier 216. [0049] While the above examples have employed the electric motor 22 as part of an actuator A (Figs. 1 and 3) that is configured to change an operational state of the clutch 24, 24a, it will be appreciated that an engine accessory constructed in accordance with the teachings of the present disclosure can be constructed somewhat differently. For example, a pneumatic or hydraulic cylinder can be employed to cause shifting of a desired element, such as the rotor of the electric motor, or a portion of the clutch (e.g., the clutch output member 122 of Fig. 1 or the carrier 216 of Fig. 3). In the example of Figures 6 through 9, the accessory 10b is generally similar to the accessory 10a (Fig. 3) except that the actuator A comprises a solenoid 300 and the clutch 24b employs a clutch spring 210b that is configured to engage first and second clutch surfaces 212b and 214b, respectively, that are formed on the outside diameter of various elements associated with the input and the output of the drive portion 12b. The input coils 220b of the clutch spring 210b are driving engaged to the first clutch surface 212b.

[0050] The solenoid 300 can comprise an electromagnet 310 and an armature 312. The electromagnet 310 can be constructed in a conventional manner and can be fixedly coupled to the stator 60 and the drive housing 16 in any desired manner. In the particular example provided, the electromagnet 310 is received into a pocket 320 that is formed in the stator 60 and a spring washer 322, which is received into a spring pocket 324 that is formed in a portion of the drive housing 16 and disposed between the drive housing 16 and the electromagnet 310, is employed to exert a seating force onto the electromagnet 310 that fixedly and non-rotatably seats the electromagnet 310 to the stator 60.

[0051] With reference to Figures 8 and 9, the armature 312 can include an armature body 330 and an armature flange 332. The armature body 330 can include a circumferential wall 340 and an annular end piece 342 that can be fixedly coupled to a first axial end of the circumferential wall 340. The armature body 330 can be fixedly coupled to the carrier 216 in any desired manner. In the example provided, the circumferential wall 340 is engaged to the outside diametrical surface of the carrier 216 in a press-fit manner such that the annular end piece 342 is abutted against an axial end of the carrier 216 that is opposite the clutch spring 210b. It will be appreciated, however, that various other coupling methods, such as threads, mechanical fasteners and/or bonding via an adhesive, brazing or welding, could be employed to fixedly (axially and rotationally) couple the armature 312 to the carrier 216. The armature flange 332 can extend radially outwardly from the armature body 330 and at least a portion of the armature flange 332 can be disposed in-line with the electromagnet 310.

[0052] With reference to Figures 6 and 8, the accessory 10b can be operated in a mechanically-driven mode in which rotary power from the drive element 20 is exclusively employed to drive the output shaft 18b. In this mode, rotation of the drive element 20 causes corresponding rotation of the input coils 220. It will be appreciated that the wire of the clutch spring 210b is wound so that rotation of the drive element 20 in a predetermined rotational direction works to wind the input coils 220b so that the input coils 220b more securely engage the first clutch surface 212b. Electrical power is provided to the electromagnet 310 to cause the electromagnet 310 to generate a magnetic field. The magnetic field acts on the armature flange 332 to cause the armature 312 (and the carrier 216 with it) to translate toward and frictionally engage a structure that is fixed to the output shaft 18b for rotation therewith. The structure could be assembled to the output shaft 18b or could be unitarily and integrally formed with the output shaft 18b. In the example provided, the structure is the rotor 62b of the electric motor 22. Frictional engagement of the armature 312 (via the annular end piece 342) with the rotor 62b (which is depicted in Fig. 8) creates a drag force that is transmitted to the carrier 216. The drag force imparted to the carrier 216 slows or resists its rotation relative to that of the drive element 20, causing the output coils 222b of the clutch spring 210b to wind down from their normal condition (in which the output coils 222b are not drivingly engaged to the second clutch surface 214b so that relative rotation between the output coils 222b and the output shaft 18b is permitted) to an engaged condition in which the output coils 222 are drivingly engaged to the second clutch surface 214b. Those of skill in the art will appreciate that driving engagement of the output coils 222b to the second clutch surface 214b couples (via the clutch spring 210) the drive element 20 to the output shaft 18b. [0053] The accessory 10b can also be operated in another mode in which only the electric motor 22 is capable of providing rotary power to the output shaft 18b. In this mode, the electromagnet 310 is not operated and does not create a magnetic field to attract the armature flange 332. Since there is no magnetically-generated force that would urge the armature 312 (and the carrier 216 with it) to move along the rotary axis 54 toward the rotor 62b, the carrier 216 (and the armature 312 with it) is biased by the clutch spring 210b along the rotary axis 54 to the position that is depicted in Figure 6. In this position, the annular end piece 342 of the armature body 330 is offset from rotor 62b (or another suitable structure that is coupled to the output shaft 18b for rotation therewith) so that no drag force is transmitted from the armature 312 to the carrier 216. As such, the output coils 222b are maintained in their normal condition, which permits relative rotation between the output coils 222b and the second clutch surface 214 so that the output shaft 18b is rotationally decoupled from the drive element 20. The electric motor 22 can be operated in this mode to provide rotary power to drive the output shaft 18b. Optionally, the drive portion 12b could be operated in a sub- mode in which the electric motor 22 is maintained in a non-operational (i.e., non-rotating) state so that the output shaft 18b is not actively driven. In the example provided, operation in this sub-mode may be desirable in situations where a supply of engine coolant is not desired, such as when the engine is cold and being started.

[0054] It will be appreciated that as the rotor 62b does not translate along the rotary axis 54 in this example, the electric motor 22 can be any type of electric motor. Optionally, the actuator - and/or the structure that is coupled to the output shaft 18b for rotation therewith (i.e., the rotor 62b in the example provided) could include a friction material so that the frictional characteristics of the armature-to-structure interface are within desired limits.

[0055] From the foregoing, it will be appreciated that while the clutch 24b of the accessory 10b is configured as a normally-disengaged clutch so that rotary power is not transmitted between the drive element 20 and the output shaft 18b unless the actuator A is operated. It will also be appreciated that the clutch 24b of the accessory 10b could be configured in the alternative as a normally-engaged clutch so that rotary power is transmitted between the drive element 20 and the output shaft 18b unless the actuator A is operated. In such case, the armature 312 could be biased by a spring (not shown) toward the electromagnet 310 to cause the armature 312 to frictionally engage the structure (e.g., rotor 62) that is coupled for rotation with the output shaft 18b. Drag force generated through frictional contact between the armature 312 and the structure (e.g., rotor 62b) somewhat slows or resists the rotation of the carrier 216 relative to the drive member - so that the output coils 222b wind down and frictionally engage the second clutch surface 214b to thereby drivingly couple the output shaft 18b to the drive element 20. In this example, the provision of electric power to the electromagnet 310 generates a magnetic field that drives the armature 312 along the rotary axis 54 away from the structure (e.g., rotor 62b) so that rotation of the carrier 216 (and the output coils 222b) relative to the drive element 20 is not slowed or resisted. In this condition, the output coils 222b return to their normal state and disengage the second clutch surface 214b to permit the output shaft 18b to rotate relative to the drive element 20.

[0056] While the actuator of the accessory of the examples of Figures 1 and 3 has been illustrated and described as being an electric motor having a generally cylindrically-shaped rotor that is received into a cylindrical bore formed in a stator, it will be appreciated that the actuator could be constructed somewhat differently, as is depicted schematically in Figures 10 through 12.

[0057] With specific reference to Figure 10, the rotor 62c and the stator 60c are depicted as having frusto-conical exterior and interior surfaces 400 and 402, respectively. Configuration in this manner places a portion of the exterior surface 400 of the rotor 62c axially in-line with a portion of the interior surface 402 on the stator 60c so that the actuator A generates a higher axially-directed force (relative to the actuator depicted in the examples of Figures 1 and 3) when the actuator A is operated (i.e., during operation of the electric motor 22).

[0058] The example of Figure 1 1 employs a stepped diameter rotor 62d that is received into a stepped diameter stator 60d to achieve relatively higher axially-directed forces on the rotor 62d when the actuator A is operated. In this example, the rotor 62d has two differently sized cylindrical sections 420 and 422 with a shoulder 424 formed there between, while the stator 60d has a pair of correspondingly sized cylindrical sections 430 and 432 with a shoulder 434 formed there between. The cylindrical sections 430 and 432 of the stator 60d are sized to receive the associated cylindrical sections 420 and 422, respectively, of the rotor 62d. The shoulders 422 and 432 of the rotor 62d and the stator 60d are disposed axially in-line with one another so that the actuator A generates a higher axially-directed force (relative to the actuator depicted in the examples of Figures 1 and 3) when the actuator A is operated (i.e., during operation of the electric motor 22).

[0059] The example of Figure 12 is similar to that of Figure 1 1 , except that the rotor 62e and the stator 60e are formed with multiple shoulders 424, 424a and 434, 434a, respectively.

[0060] 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.

Claims

CLAIMS What is claimed is:

1 . An accessory (10, 10a, 10b) comprising:

an drive portion (12) having a drive housing (16), drive element (20), an output shaft (18, 18a, 18b), an electric motor (22), a clutch (24, 24a, 24b) and an actuator (A), the drive housing (16) defining a cavity (40), the drive element (20) being disposed for rotation about a rotary axis (54), the output shaft (18, 18a, 18b) being received in the housing and disposed for rotation about the rotary axis (54), the electric motor (22) being received in the cavity (40) and having a stator (62) and a rotor (62, 62b), the stator (62) being fixed to the drive housing (16), the rotor (62, 62b) being drivingly coupled to the output shaft (18, 18a, 18b), the clutch (24, 24a, 24b) being operable in pair of operational modes that comprise a first mode, in which rotary power is transmitted between the drive element (20) and the output shaft (18, 18a, 18b), and a second mode in which rotary power is not transmitted between the drive element (20) and the output shaft (18, 18a, 18b), the actuator (A) being configured to selectively move of a portion of the clutch (24, 24a, 24b) along the rotary axis (54) to change the operational mode of the clutch (24, 24a, 24b).

2. The accessory (10, 10a, 10b) of Claim 1 , wherein the actuator (A) comprises the electric motor (22), wherein the rotor (62, 62b) is non- rotatably but axially slidably coupled to the output shaft (18, 18a, 18b), wherein the portion of the clutch (24, 24a, 24b) is fixedly coupled to the rotor (62, 62b), wherein the stator (60) has a plurality of stator poles (70) that are disposed along the stator (60) at a first nominal location (68), wherein the rotor (62, 62b) has a plurality of rotor poles (1 10) that are disposed along the rotor (62, 62b) at a second nominal location (1 18), and wherein the stator (60) and the rotor (62, 62b) are configured to generate respective magnetic fields when the electric motor (22) is operated, the first and second magnetic fields being configured to move the rotor (62, 62b) along the rotary axis (54) to more closely align the first and second nominal positions (68, 1 18).

3. The accessory (10, 10a, 10b) of Claim 1 , wherein the actuator (A) comprises an electromagnetic coil (310) and an armature (312) that is configured to be translated by the electromagnetic coil (310) to engage another element of the accessory (10, 10a, 10b) to create a drag force that changes an operational state of the clutch (24, 24a, 24b).

4. The accessory (10, 10a, 10b) of any one of Claims 2 and 3, wherein the clutch (24, 24a, 24b) comprises a clutch input member (120), a clutch output member (122) and a biasing spring (124), the clutch input member (120) being coupled to the drive element (20) for rotation therewith, the clutch output member (122) being fixedly coupled to the rotor (62, 62b), biasing spring (124) that is configured to bias one of the clutch input member (120) and the clutch output member (122) along the rotary axis (54) in a predetermined direction.

5. The accessory (10, 10a, 10b) of Claim 4, wherein the biasing spring (124) biases the one of the clutch input member (120) and the clutch output member (122) toward the other one of the clutch input member (120) and the clutch output member (122).

6. The accessory (10, 10a, 10b) of any one of Claims 2 and 3, wherein the electric motor (22) is one of an induction motor, a reluctance motor and a switched reluctance motor.

7. The accessory (10, 10a, 10b) of any one of Claims 2 and 3, wherein the clutch (24, 24a, 24b) comprises a clutch spring (210, 210b) having a plurality of input coils (220, 220b) that are engaged to a first clutch surface (214, 214b) that is coupled to the drive element (20) for rotation therewith.

8. The accessory (10, 10a, 10b) of Claim 7, wherein the first clutch surface (214, 214b) is an inside diametrical surface.

9. The accessory (10, 10a, 10b) of Claim 7, wherein the clutch spring (210, 210b) has a plurality of output coils (222, 222b) that engage a second clutch surface (214, 214b) that is coupled for rotation with the output shaft (18, 18a, 18b).

10. The accessory (10, 10a, 10b) of Claim 9, wherein the second clutch surface (214, 214b) is an inside diametrical surface.

1 1 The accessory (10, 10a, 10b) of Claim 9, wherein the second clutch surface (214, 214b) is formed on the rotor (62, 62b).

12. The accessory (10, 10a, 10b) of Claim 9, wherein the second clutch surface (214, 214b) is formed on the output shaft (18, 18a, 18b).

13. The accessory (10, 10a, 10b) of Claim 9, wherein the plurality of output coils (222, 222b) are normally engaged to the second clutch surface (214, 214b) and the actuator (A) is operated to cause the output coils (222, 222b) to disengage the second clutch surface (214, 214b).

14. The accessory (10, 10a, 10b) of Claim 2, wherein the rotor (62, 62b) is tapered or stepped and the stator (60, 60b) is shaped to correspond to the rotor (62, 62b).

15. The accessory (10, 10a, 10b) of any one of the preceding claims, wherein the drive element (20) is a pulley.

16. The accessory (10, 10a, 10b) of any one of the preceding claims, further comprising an accessory portion (14) having an accessory housing (30), an accessory shaft (32) and an accessory work element (34), the accessory housing (30) being fixedly coupled to the drive housing (16), the accessory shaft (32) being coupled for rotation with the output shaft (18, 18a, 18b), the accessory work element (34) being drivingly coupled to the accessory shaft (32).

17. The accessory (10, 10a, 10b) of Claim 16, wherein the accessory work element (34) is an impeller.

18. A method for operating an accessory (10, 10a, 10b) having a drive element (20), a rotary electric motor (22), an output shaft (18, 18a) and a clutch (24, 24a), the rotary electric motor (22) having a stator (60) and a rotor (62), the rotor (62) being non-rotatably but axially slidably coupled to the output shaft (18, 18a), the clutch (24, 24a) being operable in a first state, in which the clutch (24, 24a) is configured to transmit rotary power between the drive element (20) and the output shaft (18, 18a), and a second state in which the clutch (24, 24a) is configured to decouple the drive element (20) from the output shaft (18, 18a), the method comprising:

rotating the drive element (20) while not operating the electric motor (22) to transmit rotary power from the drive element (20) through the clutch (24, 24a) to the output shaft (18, 18a); and

operating the electric motor (22) to apply a magnetically-generated force to the rotor (62) and to rotate the output shaft (18, 18a), wherein the magnetically-generated force has a magnitude that shifts the rotor (62) along the rotary axis (54) so that the clutch (24, 24a) operates in the second state.