BACKGROUND OF THE INVENTION

1. Field of the Invention

[0001] The present invention relates, generally, to automotive transmission systems and, more specifically, to a rotary shifter assembly for changing gears in a vehicle transmission.

2. Description of the Related Art

[0002] Conventional automotive powertrain systems known in the art include an engine in rotational communication with a transmission. The engine generates rotational torque which is selectively translated to the transmission which, in turn, translates rotational torque to one or more wheels to drive a vehicle. The transmission multiplies the rotational speed and torque generated by the engine through a series of predetermined gear sets, whereby changing between gear sets enables the vehicle to travel at different vehicle speeds for a given engine speed. Thus, the gear sets of the transmission are configured such that the engine can operate at particularly desirable rotational speeds so as to optimize performance and efficiency.

[0003] There are a number of different types of automotive transmissions known in the art. As such, changing between gear sets can be accomplished in a number of different ways, depending on the type of transmission. For example, so- called "manual" transmission systems typically include a clutch disposed between the engine and transmission for modulating engagement therebetween, and a shifter for changing between gear sets. The clutch and shifter are both mechanically connected to the manual transmission and are driver-actuated. In operation, the driver can manipulate the clutch and shifter to move the transmission between a freewheel "neutral" configuration, a "reverse" gear, and one or more forward gears, such as "first," "second," "third," "forth," etc. Thus, the driver determines when to change between gear sets and operates the shifter and clutch "manually".

[0004] So-called "automatic" transmission systems, on the other hand, require substantially less driver input and use an electronic transmission controller that drives one or more solenoids to effect changing between forward gear sets. Solenoids are also used to modulate engagement between the engine and transmission. In conventional automatic transmission systems, modulation is achieved using a hydraulic torque converter. However, modem transmission systems may replace the torque converter with one or more electronically and/or hydraulically actuated clutches (sometimes referred to in the art as a "dual clutch" automatic transmission). In addition, conventional manual transmissions may be automated, whereby electronic actuators are used to shift between gear sets and modulate the clutch without relying exclusively on operator interaction. Irrespective of how modulation is effected, automatic transmission systems rely on the transmission controller to determine when to change between forward gear sets. Thus, the transmission controller "automatically" modulates engagement between the engine and transmission and shifts between forward gear sets.

[0005] Despite the convenience afforded by automatic transmission systems in changing between forward gear sets, driver interaction is still required to select between different vehicle operating modes, such as "park," "reverse," "neutral," "drive," and/or "sport/manual." To that end, the automatic transmission system also includes a shifter assembly in communication with the transmission and/or transmission controller. [0006] Historically, shifter assemblies used with automatic transmissions were mechanically connected to the transmission via one or more linkages and/or cables. However, given the trend in the art of utilizing electronic actuators to control automatic transmission systems, modem shifter assemblies are increasingly designed as "drive-by-wire" so as to control the transmission electronically and without mechanical linkages and/or cables. By eliminating mechanical linkages and cables connected to the transmission, electronic shifter assemblies provide significant advantages with respect to packaging size, weight, orientation, and placement within the vehicle. Moreover, electronic shifter assemblies provide opportunities for controlling transmission systems with enhanced functionality and features.

[0007] While shifter assemblies known in the prior art have generally performed well for their intended purpose, there remains a need in the art for an improved electronic shifter assembly that strikes a substantial balance between packaging size, component cost, manufacturability, functionality, usability, and ergonomics.

SUMMARY OF THE INVENTION AND ADVANTAGES

[0008] The present invention overcomes the disadvantages in the related art in a shifter assembly for changing gears in a vehicle transmission. The shifter assembly includes a housing and a shift selector rotatably supported in the housing. The shift selector is selectively movable between a plurality of radial positions, including a home position and an operational position. The shifter assembly also includes a motor operatively attached to the housing. The motor has a locked condition, and an operational condition generating rotational toque to move the shift selector towards the home position. In addition, the shifter assembly includes a clutch mechanism including a first clutch member coupled to the shift selector and movable between the plurality of radial positions in unison with the shift selector, and a second clutch member disposed in rotational communication with the motor. The clutch mechanism is operable between: a first operating mode, a second operating mode, and a third operating mode. In the first operating mode, the first clutch member rotates relative to the second clutch member during the movement of the shift selector between the radial positions while the motor is in the locked condition. In the second operating mode, rotational torque generated by the motor while in the operational condition rotates the second clutch member relative to the first clutch member. In the third operating mode, rotational torque generated by the motor while in the operational condition rotates the first clutch member concurrently with the second clutch member to facilitate movement of the shift selector towards the home position.

[0009] In this way, the shifter assembly of the present invention provides improved functionality and usability in connection with automatic transmission systems and, at the same time, reduces the cost and complexity of manufacturing and assembling shifter assemblies.

BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Other advantages of the present invention will be readily appreciated, as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings.

[0011] Figure 1 is a perspective view of a shifter assembly according to one embodiment of the present invention. [0012] Figure 2 is a partially exploded perspective view of the shifter assembly of Figure 1, showing a knob, a main housing with a shift selector, and a pair of main housing covers.

[0013] Figure 3 is another partially exploded perspective view of the shifter assembly of Figures 1 -2.

[0014] Figure 4A is a front plan view of the shifter assembly of Figures 1-2, showing the shift selector rotatably arranged in a first radial position and axially arranged in a first axial position.

[0015] Figure 4B is another front plan view of the shifter assembly of Figures 1 -4A, showing the shift selector rotatably arranged in a second radial position and axially arranged in the first axial position.

[0016] Figure 4C is another front plan view of the shifter assembly of Figures 4A-4B, showing the shift selector rotatably arranged in a third radial position and axially arranged in the first axial position.

[0017] Figure 4D is another front plan view of the shifter assembly of Figures 4A-4C, showing the shift selector rotatably arranged in a fourth radial position and axially arranged in the first axial position.

[0018] Figure 4E is another front plan view of the shifter assembly of Figures 4A-4D, showing the shift selector rotatably arranged in a third radial position and axially arranged in a second axial position.

[0019] Figure 5A is a partial perspective view of the shifter assembly of Figures 1-4E, showing a portion of the main housing attached to one of the main housing covers, a motor, first and second clutch members, and the shift selector arranged as depicted in Figure 4A in the first radial position and the first axial position. [0020] Figure 5B is another partial perspective view of the shifter assembly of Figures 1-5 A, showing the shift selector arranged between the first radial position and the second radial position while in the first axial position.

[0021] Figure 5C is another partial perspective view of the shifter assembly of Figures 1-5B, showing the shift selector arranged as depicted in Figure 4B in the second radial position and the first axial position.

[0022] Figure 6A is another partial perspective view of the shifter assembly of Figures 1-5C, showing the shift selector arranged as depicted in Figure 4D in the fourth radial position and the first axial position.

[0023] Figure 6B is another partial perspective view of the shifter assembly of Figures 1-6 A, showing the shift selector arranged in the fourth radial position and the second axial position.

[0024] Figure 6C is another partial perspective view of the shifter assembly of Figures 1-6B, showing the shift selector arranged as depicted in Figure 4E in the fifth radial position and the second axial position.

[0025] Figure 7A is another partial perspective view of the shifter assembly of Figures 1-6C, showing the shift selector arranged in the fourth radial position and the first axial position so as to illustrate concurrent movement of the second clutch member with the shift selector from the firth radial position depicted in Figure 6C.

[0026] Figure 7B is another partial perspective view of the shifter assembly of Figures 1-7A, showing the shift selector arranged in the third radial position so as to illustrate further concurrent movement of the second clutch member with the shift selector from the fourth radial position depicted in Figure 7A.

[0027] Figure 7C is another partial perspective view of the shifter assembly of Figures 1-7B, showing the shift selector arranged in the first radial position so as to illustrate further concurrent movement of the second clutch member with the shift selector from the third radial position depicted in Figure 7B.

[0028] Figure 8 is another partially exploded perspective view of the shifter assembly of Figures 1-7C, showing the shift selector, first and second clutch members, motor, and one of the main housing covers.

[0029] Figure 9 is a sectional view taken along line 9-9 in Figure 4A.

DETAILED DESCRIPTION OF THE INVENTION

[0030] With reference now to the Figures, wherein like numerals indicate like parts throughout the several views, a shifter assembly is shown at 20 in Figure 1. The shifter assembly 20 is used to change gears in a vehicle transmission 22 (shown schematically in Figure 3 and generally known in the art). More specifically, the shifter assembly 20 cooperates with an automatic transmission 22 of a vehicle so as to enable a driver to operate the transmission 22 in a plurality of vehicle operating modes, such as "park," "neutral," "reverse," "drive," and "sport." To that end, the shifter assembly 20 is in electrical communication with one or more electronic control units 24 (shown schematically in Figure 3 and generally known in the art), such as an engine or transmission controller which, in turn, is responsive to predetermined signals generated by the shifter assembly 20 and can subsequently control the automatic transmission 22 as required.

[0031] The electronic control unit 24 drives one or more actuators, such as solenoids (not shown, but generally known in the art) to control the transmission 22. Specifically, the electronic control unit 24 drives the actuators so as to switch the automatic transmission 22 between the vehicle operating modes, as selected by the driver. The electronic control unit 24 also moves the automatic transmission 22 between a plurality of predetermined transmission gear sets when the shifter assembly 20 is in the "drive" operating mode. However, those having ordinary skill in the art will appreciate that the shifter assembly 20 of the present invention could be used in connection with an automatic transmission 22 controlled in any suitable way, with or without an electronic control unit 24 or actuators as described above, without departing from the scope of the present invention. Moreover, it will be appreciated that the shifter assembly 20 of the present invention can be used in connection with any suitable type of transmission 22. By way of non-limiting example, the transmission 22 could be a conventional automatic that employs a torque converter, a modem automatic that employs one or more electronically and/or hydraulically actuated clutches, or a conventional manual with an automatically actuated clutch.

[0032] As noted above, the shifter assembly 20 is adapted to control the automatic transmission 22 between a plurality of operating modes— in the representative embodiment illustrated herein, five different modes. However, as will be appreciated from the subsequent description of the shifter assembly 20 below, the present invention could also control other types of vehicle systems, between any suitable number of discrete operating modes. By way of non-limiting example, the shifter assembly 20 could be used to control transfer case assemblies, all-wheel-drive systems, differential torque biasing systems, or any other type of automotive system or sub-system, without departing from the scope of the present invention. Moreover, while the present invention is adapted for use with automotive passenger vehicles, it will be appreciated that the shifter assembly 20 could be used in connection with any type of vehicle, such as heavy-duty trucks, trains, airplanes, ships, construction vehicles or equipment, military vehicles, or any other type of vehicle that utilizes an automatic transmission or torque transfer system. [0033] Referring now to Figures 2-7C, the shifter assembly 20 of the present invention includes a housing 26 and a shift selector 28 rotatably supported in the housing 26. The shift selector 28 is selectively moveable between a plurality of radial positions, including a home position RH and an operational position RO. A motor 30 is operatively attached to the housing 26 and has a locked condition LC and an operational condition OC. In the operational condition OC, the motor 30 generates rotational torque to move the shift selector 28 towards the home position RH. The shifter assembly 20 is also provided with a clutch mechanism 32 having a first clutch member 34 and a second clutch member 36. The first clutch member 34 is coupled to the shift selector 28 and is movable between the plurality of radial positions in unison with the shift selector 28, and the second clutch member 36 is disposed in rotational communication with the motor 30. The clutch mechanism 32 is operable between a first operating mode OM1, a second operating mode OM2, and a third operating mode OM3. When the clutch mechanism 32 is in the first operating mode OM1, the first clutch member 34 rotates relative to the second clutch member 36 during movement of the shift selector 28 between the radial positions while the motor 30 is in the locked condition LC. When the clutch mechanism 32 is in the second operating mode OM2, rotational torque generated by the motor 30 while the motor 30 is in the operational condition OC rotates the second clutch member 36 relative to the first clutch member 34. When the clutch mechanism 32 is in the third operating mode OM3, rotational torque generated by the motor 30 while the motor 30 is in the operational condition OC rotates the first clutch member 34 concurrently with the second clutch member 36 to facilitate movement of the shift selector 28 towards the home position RH. The housing 26, shift selector 28, motor 30, and clutch mechanism 32 will each be described in greater detail below. [0034] The housing 26 is formed from a plurality of elements that interlock or otherwise cooperate to accommodate and support the various components of the shifter assembly 20. As is illustrated throughout the Figures, the housing 26 includes a main housing body 38 and front and rear housing covers 40A, 40B. As is described in greater detail below, the main housing body 38 and the rear housing cover 40B cooperate to rotatably support the shift selector 28. The rear housing cover 40B also supports the motor 30 and the second clutch member 36 of the clutch mechanism 32 (see Figures 5A-7C). This configuration simplifies both the manufacturing and assembly of the shifter assembly 20 and also optimizes the overall packaging size of the shifter assembly 20. However, it will be appreciated that the housing 26 could be formed from any suitable number of elements, or from a single element, without departing from the scope of the present invention.

[0035] As noted above, the shift selector 28 is selectively moveable between the plurality of radial positions including the home position RH and the operational position RO. More specifically, and in the representative embodiment illustrated herein, the shift selector 28 cooperates with the electronic control unit 24 so as to allow the driver to move the shift selector 28 between a first radial position Rl, a second radial position R2, a third radial position R3, a fourth radial position R4, and a fifth radial position R5, which respectively correspond to "park," "reverse," "neutral," "drive," and "sport" vehicle operating modes of the transmission 22. In the description which follows and as is illustrated throughout the Figures, the first radial position Rl (representing "park") corresponds to and may be interchangeably referred to as the home position RH. Similarly, any one of the second, third, fourth, and/or fifth radial positions R2, R3, R4, R5 (respectively representing "reverse," "neutral," "drive," and "sport") may correspond to and may interchangeably referred to as the operational positon RO.

[0036] In the representative embodiment illustrated herein, cooperation between the motor 30 and the clutch mechanism 34 allows the driver to move between the radial positions in a smooth, consistent manner while the clutch mechanism 32 is in the first operating mode OM1. Moreover, the specific configuration of the clutch mechanism 34 affords the driver with haptic feedback as the shift selector 28 moves between radial positions. To these ends, in one embodiment, the second clutch member 36 includes a plurality of radially spaced detents 42 each representing respective radial positions of the shift selector 28, and the first clutch member 34 includes a detent plunger 44 selectively engaging one of the detents 42 so as to at least partially resist rotation of the shift selector 28 relative to the second clutch member 36. Thus, the detent plunger 44 holds the shift selector 28 in one of the detents 42 until the driver applies enough rotational torque to overcome engagement between the detent plunger 44 and the detent 42 to move the detent plunger 44 into an adj acent detent 42 (compare Figures 5A-5C).

[0037] The second clutch member 36 has a substantially ring-shaped profile with an inner surface 46 and an opposing outer surface 48 (see Figure 8). Here, a total of twenty equally-spaced detents 42 each having a curved profile are provided along the inner surface 46 of the second clutch member 36. However, those having ordinary skill in the art will appreciate that the second clutch member 36 could have any number of detents 42 with any suitable shape or profile, or could have any other configuration sufficient to effect movement of the shift selector 28 between the radial positions, without departing from the scope of the present invention. It will be appreciated that the specific number of detents 42, as well as the shape and orientation of the detents 42 and the detent plunger 44, can be adjusted to accommodate different applications of the shifter assembly 20, such as where a different number transmission 22 operating modes are required.

[0038] As is described in greater detail below, in one embodiment the shift selector 28 is supported for axial translation with respect to the housing 26 between a first axial position Al and a second axial position A2. In order to accommodate axial movement of the shift selector 28, the detents 42 of the second clutch member 36 are shaped so as to remain in engagement with the detent plunger 44 as the shift selector 28 moves between the first axial position Al and the second axial position A2 (see Figures 6A-6B). Because the first clutch member 34 is coupled to and moves concurrently with the shift selector 28, the configuration of the detents 42 allows the detent plunger 44 to translate axially along the detents 42 without necessitating rotational movement of the shift selector 28 between the radial positions.

[0039] As best shown in Figures 8-9, in one embodiment, the first clutch member 34 includes a detent block 50 defining a cavity 52 to slidably support the detent plunger 44 therein. Here, the detent block 50 is formed integrally with the shift selector 28 and is arranged transverse to rotation of the shift selector 28. However, those having ordinary skill in the art will appreciate that the first clutch member 34 could be configured so as to attach to or otherwise move concurrently with the shift selector 28 in a number of different ways without departing from the scope of the present invention. By way of non-limiting example, the detent block 50 could be formed as a separate component from the shift selector 28 (not shown).

[0040] With continued reference to Figures 8-9, in one embodiment, the first clutch member 34 includes a pair of opposing detent plungers 44 each arranged for respective engagement with one of the detents 42 of the second clutch member 36. The detent plungers 44 each have a stepped, generally cylindrical profile and are complimentarily shaped to the detents 42 so as to promote engagement and to ensure smooth, consistent rotation of the shift selector 28 when the clutch mechanism 32 is in the first operating mode. However, those having ordinary skill in the art will appreciate that the detent plungers 44 could be of any suitable type or configuration sufficient to engage the detents 42 of the second clutch member 36. By way of non- limiting example, the detent plungers 44 could have a cylindrical profile with a spherical end (not shown). While a pair of detent plungers 44 is advantageous for use in certain applications, such as where design requirements dictate double redundancy, it will be appreciated that a single detent plunger 44 could be employed. In addition, while the clutch mechanism 32 illustrated herein employs detents 42 formed in the second clutch member 36 and detent plungers 44 associated with the first clutch member 34, those having ordinary skill in the art will appreciate that this arrangement could be interchanged without departing from the scope of the present invention.

[0041] In one embodiment, a detent biasing element 54 is disposed in force- translating relationship between the opposing detent plungers 44 and is arranged so as to urge the detent plungers 44 away from each other and into respective engagement with one of the detents 42 of the second clutch member 36. Thus, rotation of the shift selector 28 urges the opposing detent plungers 44 towards each other to compress the detent biasing element 54 as the shift selector 28 moves between the radial positions when the clutch mechanism 32 is in the first operating mode OM1 , as noted above (compare Figures 5A-5C). Here, the detent biasing element 54 is realized as a single compression spring supported in the cavity 52 between the pair of detent plungers 44. However, it will be appreciated that the detent biasing element 54 could be of any suitable type or configuration without departing from the scope of the present invention. Moreover, those having ordinary skill in the art will appreciate that a pair of detent biasing elements 54 could be provided, each supported in a respective cavity 52 and each arranged in engagement one of the detent plungers 44. Similarly, a single detent biasing element 54 could be employed in connection with a single detent plunger 44.

[0042] With reference now to Figures 5A-7C, as noted above, the motor 30 of the shifter assembly 20 operates between the locked condition LC and the operational condition OC and cooperates with the clutch mechanism 32 to facilitate movement between the operating modes OM1, OM2, OM3. For illustrative purposes, a reference arrow REF is shown in Figures 5A-7C to depict the relative position of the second clutch member 36 with respect to the housing 26.

[0043] When in the operational condition OC, the motor 30 generates rotational torque which is translated to the second clutch member 36 so as to rotate the second clutch member 36 with respect to the housing 26. Here, as is best shown in Figures 8-9, the second clutch member 36 is supported for rotation within a bearing boss 56 formed in the rear housing cover 40B, and the motor 30 is operatively attached to the rear housing cover 40B, such as by removable fasteners 58, and is arranged to generate rotational torque and to translate rotational torque to the second clutch member 36. To this end, in one embodiment, the motor 30 includes a driving gear 60 and the second clutch member 36 includes external threads 62 disposed in meshing engagement with the driving gear 60 (see Figure 8) such that rotation of the motor 30 in the operational condition OC rotates the second clutch member 36 (compare location of reference arrow REF in Figures 6B-7C).

[0044] When the motor 30 operates in the locked condition LC, engagement between the motor 30 and the clutch mechanism 32 prevents the second clutch member 36 from moving with respect to the housing 26 (compare location of reference arrow REF in Figures 5A-6B). Specifically, the external threads 62 of the second clutch member 36 cooperate with the driving gear 60 of the motor 30 to prevent rotation of the second clutch member 36 when the motor 30 operates in the locked condition LC. In the representative embodiment illustrated herein, the driving gear 60 of the motor 30 is a worm gear and the external threads 62 of the second clutch member 36 have a helical profile. It will be appreciated that the worm/helical engagement between the driving gear 60 and the external threads 62 contributes to operation of the motor 30 in the locked condition LC. Here, so-called "back driving" of the motor 30 is effectively prevented via rotation of the shift selector 28 because of the implementation of the clutch mechanism 32 and because of the engagement between the motor 30 and the second clutch member 36. Here, the clutch mechanism 32 is advantageously implemented so as to limit the amount of rotational torque which can be translated from the shift selector 28 to the second clutch member 36. Specifically, the amount of rotational torque which can be applied to the shift selector 28 before the shift selector 28 will move between the radial positions is less than the amount of rotational torque which is required to "back drive" the motor 30 via rotation of the second clutch member 36 because of resistance occurring between the driving gear 60 and the external threads 62.

[0045] The use of the worm/helical engagement between the driving gear 60 and the external threads 62 advantageously affords opportunities for the use of motors 30 which are relatively inexpensive, such as conventional brushed DC electric motors. However, those having ordinary skill in the art will appreciate that the motor 30 could be of any suitable type or configuration sufficient to operate between the locked condition LC and the operational condition OC described above, without departing from the scope of the present invention. Similarly, it will be appreciated that rotational torque generated by the motor 30 can be translated to the second clutch member 36 while in the operational condition OC in a number of different ways, with or without the use of worm/helical meshing. By way of non-limiting example, a reduction geartrain with a plurality of spur gears could be interposed between the motor 30 and the second clutch member 36 (not shown).

[0046] Referring now to Figures 3-4E, in one embodiment, the shifter assembly 20 includes an indexing wheel 64 supported in rotational communication with the shift selector 28 for concurrent rotation between the radial positions. Here, the indexing wheel 64 is mounted to the shift selector 28 via a spline arrangement, generally indicated at 66, and is accommodated between the main housing body 38 and the front housing cover 40A. The spline arrangement 66 simplifies the process of assembling the shifter assembly 20 and, at the same time, ensures angular correspondence between the indexing wheel 64 and and the shift selector 28. However, it will be appreciated that the shift selector 28 and indexing wheel 64 could be formed from any number of components that cooperate or interlock in any suitable way, with or without the use of the spline arrangement 66, without departing from the scope of the present invention.

[0047] Referring now to Figures 6A-6B, in the representative embodiment illustrated herein, the shift selector 28 and the indexing wheel 64 are concurrently supported for axial translation with respect to the housing 26 between the first axial position Al and the second axial position A2. In one embodiment, the shifter assembly 20 further includes a reference wheel 68 disposed in rotational communication with the indexing wheel 64 and arranged to remain in rotational communication with the indexing wheel 64 as the shift selector 28 moves between the first axial position Al and the second axial position A2. To this end, the indexing wheel 64 and the reference wheel 68 both have a spur-gear configuration and are arranged to remain in meshing relationship during relative axial movement therebetween. Specifically, the reference wheel 68 remains axially fixed relative to the housing 26 and the indexing wheel 64 is sized and shaped to remain in meshing engagement with the reference wheel 68 as the shift selector 28 moves between the axial positions Al , A2 (see also Figure 9).

[0048] The reference wheel 68 is provided to determine the rotational position of the shift selector 28 between the radial positions. To this end, in one embodiment, at least one emitter 70 is operatively attached to the reference wheel 68, and at least one detector 72 is operatively attached to the housing 26. The detector 72 is responsive to predetermined positional changes of the emitter 70 so as to determine movement of the shift selector 28 between the radial positions.

[0049] In the representative embodiment illustrated herein, the detector 72 and the emitter 70 cooperate to define a rotational position sensor 74 disposed in communication with the shift selector 28 and configured to determine a relative rotational position of the shift selector 28 between the radial positions. Here, the rotational position sensor 74 is realized as a rotary potentiometer mounted on a printed circuit board 76 which, in turn, is operatively attached to the housing 26, such as by fasteners 58. The reference wheel 68 is mounted to the rotational positions sensor 74 such that rotation of the reference wheel 68 corresponds to relative radial position of the shift selector 28. Those having ordinary skill in the art will appreciate that the rotational position sensor 74, the detector 72, and/or the emitter 70 could be configured or arranged in any suitable way sufficient to communicate positional changes in the shift selector 28 without departing from the scope of the present invention.

[0050] Referring now to Figures 3, 6A-6B, 8, and 9, in one embodiment, at least one emitter 70 is operatively attached to the shift selector 28, and at least one detector 72 is operatively attached to the housing 26 and is responsive to predetermined positional changes of the emitter 70 so as to determine movement of the shift selector 28 between the axial positions Al , A2 (see Figures 6A-6B). Here, the emitter 70 has an annular configuration and is operatively attached to the indexing wheel 64 for concurrent movement (see Figure 9), and the detector 72 is mounted to the printed circuit board 76 arranged adjacent to the indexing wheel 64. In this embodiment, the emitter 70 and the detector 72 cooperate to communicate axial position of the shift selector 28, while the rotational position sensor 74 communicates rotational position of the shift selector 28.

[0051] As is best shown in Figures 8-9, in one embodiment, the shifter assembly 20 includes a selector biasing element 78 arranged between the shift selector 28 and the rear housing cover 40B. The selector biasing element 78 urges the shift selector 28 towards the first axial position Al and is realized as a compression spring. However, it will be appreciated that the shift selector 28 could be biased differently without departing from the scope of the present invention.

[0052] In one embodiment, at least one of the emitters 70 is further defined as a magnet, and the associated detector 72 is responsive to predetermined changes in magnetic fields generated by the magnet to determine the relative position of the respective emitter 70. To that end, the associated detector 72 may be of any suitable type sufficient to sense and respond to changes in magnetic fields. Moreover, it is conceivable that the emitter 70 could be manufactured from an iron-based material and the detector 72 could be a hall-effect sensor that generates a magnetic field and is capable of responding to changes in the field due to interaction of the iron-based material of the emitter 70. To that end, the emitter 70 may also be realized as a ferrous enamel, coating, paint, or the like. In one embodiment, one or more detectors 72 are disposed in electrical communication with the electronic control unit 24 such that operation of the transmission 22 can be adjusted or changed via the electronic control unit 24 based at least partially on positional changes of the shift selector 28, as described in greater detail below.

[0053] While the shifter assembly 20 of the present invention employs separate emitters 70 and detectors 72 to communicate rotational and axial position of the shift selector 28, those having ordinary skill in the art will appreciate that any suitable number of emitters 70 and/or detectors 72 could be employed without departing from the scope of the present invention. Moreover, it will be appreciated that the emitters 70 and/or detectors 72 could be of any suitable type, configuration, or arrangement sufficient to communicate positional changes of the shift selector 28.

[0054] Referring now to Figures 3-7C, in one embodiment, the shifter assembly 20 includes a limiting mechanism, generally indicated at 80, interposed between the indexing wheel 64 and the housing 26 and configured to limit rotation of the shift selector 28 between the home position RH and the operational position RO of the plurality of radial positions. To this end, in one embodiment, the limiting mechanism 80 includes a gate 82 defined in one of the housing 26 and the indexing wheel 64, and a stop member 84 operatively attached to the other of the housing 26 and the indexing wheel 64. The stop member 84 is at least partially disposed within the gate 82 and cooperates with the gate 82 to limit rotation of the shift selector 28 between the home position RH and the operational position RO, as is described in greater detail below. In the representative embodiment illustrated herein, the gate 82 is defined in the indexing wheel 64 and the stop member 84 is operatively attached to the housing 26. However, those having ordinary skill in the art will appreciate that this arrangement could be interchanged without departing from the scope of the present invention. Moreover, as will be appreciated from the subsequent description below, the limiting mechanism 80 could be configured in a number of different ways sufficient to limit rotation of the shift selector 28.

[0055] With reference now to Figures 3-4E, in one embodiment, the gate 82 of the limiting mechanism 80 is further defined as an arcuate slot having a first slot end 86 and a second slot end 88. The first slot end 86 of the gate 82 abuts the stop member 84 when the shift selector 28 is in the home position RH (see Figure 4A; see also Figures 5A and 7C). As noted above, in the representative embodiment illustrated herein, the home position RH of the shift selector 28 corresponds to the first radial position Rl which, in turn, represents operation of the transmission 22 in "park".

[0056] In one embodiment, the second slot end 88 of the gate 82 abuts the stop member 84 when the shift selector 28 in the operational position RO. As is described in greater detail below, because the shifter assembly 20 of the present invention is configured to allow axial movement of the shift selector 28 between the first and second axial positions Al , A2, the stop member 84 is configured to abut the second slot end 88 when the shift selector 28 is in both the fourth radial position R4 representing operation of the transmission 22 in "drive" (see Figure 4D; see also Figure 6A) and the fifth radial position R5 representing operation of the transmission 22 in "sport" (see Figure 4E; see also Figure 6C). To this end, as is best shown in Figures 3 and 9, the stop member 84 has a first stop portion 90 and a second stop portion 92. The first stop portion 90 cooperates with the gate 82 to limit rotation of the shift selector 28 between the home position RH (here, the first radial position Rl) and the operational position RO (here, the fourth radial position R4) when the shift selector 28 is in the first axial position Al, and the second stop portion 92 cooperates with the gate 82 to limit rotation of the shift selector 28 between the home position RH and a second operational position RO (here, the fifth radial position R5) when the shift selector 28 is in the second axial position A2.

[0057] In the representative embodiment illustrated herein, the first stop portion 90 is shaped to abut a portion of the gate 82 to prevent rotation of the shift selector 28 from the operational position RO; R4 to the second operational position RO; R5 when the shift selector 28 is in the first axial position Al. To this end, as is best shown in Figures 3 and 9, the second stop portion 92 has a generally cylindrical profile and extends between the housing 26 and the first stop portion 90 which, in turn, has a generally arc-shaped profile. The arc-shaped first stop portion 90 abuts the second slot end 88 when the shift selector 28 is in the fourth radial position R4 and in the first axial position Al (see Figure 6A), which prevents rotation of the shift selector 28 towards the fifth radial position R5 until the shift selector 28 is moved to the second axial position A2 so as to bring the arc-shaped first stop portion 90 out of abutment with the second slot end 88 (see Figure 6B), which then allows the shift selector 28 to be moved into the fifth radial position R5 as the cylindrical second stop portion 92 comes into abutment with the second slot end 88 (see Figure 6C). Those having ordinary skill in the art will appreciate that this arrangement serves as a "lockout" to prevent inadvertent movement of the shift selector 28 from the fourth radial position R4 (the first operating mode RO corresponding to "drive") to the fifth radial position R5 (the second operating mode RO corresponding to "sport"). Thus, in order to operate the transmission 22 in "sport," the driver must first move the shift selector 28 from the first axial position Al to the second axial position A2. It will be appreciated that the lockout functionality afforded by the limiting mechanism 80 could be implemented differently, such as to limit movement between different operating modes RO.

[0058] Referring now to Figures 5A-9, in one embodiment, the shifter assembly 20 further includes a lock disc 94 and a solenoid 96. The lock disc 94 is supported in rotational communication with the shift selector 28 for concurrent rotation between the radial positions, and defines at least one receiver 98. The solenoid 96 is disposed in the housing 26 adjacent to the lock disc 94 and has a core 100 which is selectively movable between a first position 100A spaced from the lock disc 94 (see Figure 7C) and a second position 100B disposed within the receiver 98 of the lock disc 94 (see Figure 5A). Here, rotation of the shift selector 28 between the radial positions is prevented when the core 100 of the solenoid 96 is in the second position 100B.

[0059] In one embodiment, the lock disc 94 defines a plurality of receivers 98A, 98B shaped for respective engagement with the core 100 of the solenoid 96 when in the second position 100B. Here, each of the receivers 98A, 98B corresponds to a different one of the radial positions of the shift selector 28. Specifically, a first receiver 98A is arranged to accommodate the core 100 of the solenoid 96 when the shift selector 98 is in the first radial position Rl corresponding to "park," and a second receiver 98B is arranged to accommodate the core 100 of the solenoid 96 when the shift selector 98 is in the third radial position R3 corresponding to "neutral." Thus, the solenoid 96 can be used to prevent any rotation of the shift selector 98 under certain operating conditions. In one embodiment, the solenoid 96 is electromagnetically actuated by electric current so as to selectively move the core 100 between the positions 100 A, 100B, as discussed above. To that end, the solenoid 96 may be disposed in electrical communication with and actuated by the electronic control unit 24 (not shown in detail, but generally known in the art). However, it will be appreciated that the solenoid 38 could be of any suitable type sufficient to move the core 100 into the receiver 98, and could be actuated in any suitable way, without departing from the scope of the present invention

[0060] As shown best in Figure 3, the lock disc 94 and the indexing wheel 64 are realized as an integral, one-piece component such that the receivers 98 are formed in the indexing wheel 64. However, those having ordinary skill in the art will appreciate that the lock disc 94 could be formed as a separate component from the indexing wheel 64 without departing from the scope of the present invention.

[0061] In the representative embodiment of the shifter assembly 20 illustrated throughout the drawings, the shift selector 28, the detent block 50 of the first clutch member 34, the indexing wheel 64, and the lock disc 94 all rotate concurrently in response to rotational torque applied to the shift selector 28 from the driver during selection of the transmission 22 operating mode, as discussed above. To that end, in one embodiment, the shifter assembly 20 also includes a knob 102 attached to the shift selector 28 (see Figures 1 and 2). In operation, the driver rotates the knob 102 which, in turn, rotates the shift selector 28 and moves the first clutch member 34 relative to the second clutch member 36.

[0062] As will be appreciated from the subsequent description below, the shifter assembly 20 of the present invention affords significant advantages in connection with transmission 22 operation as a result of cooperation between the motor 30 and the clutch mechanism 32 and movement between the first operating mode OM1, the second operating mode OM2, and the third operating mode OM3. As noted above, when the clutch mechanism 32 is in the first operating mode OM1, rotation of the shift selector 28 causes corresponding rotation of the first clutch member 34 relative to the second clutch member 36 while the motor 30 is in the locked condition LC. Here, because the motor 30 being in the locked condition LC prevents rotation of the second clutch member 34, the first clutch member 34 allows rotation of the shift selector 28 between the radial positions and, at the same time, the first clutch member 34 acts to bias the shift selector 28 into one of the respective radial positions. It will be appreciated that this configuration allows the shifter assembly 20 to be constructed without the use of a separate mechanism employed to bias the shift selector 28 into one of the radial positions.

[0063] In use, the driver can manipulate the knob 102 of the shifter assembly 20 to operate the transmission 22 while the clutch mechanism 32 is in the first operating mode OM1 and the motor 30 is in the locked condition LC, which allows the shift selector 28 and the first clutch member 34 to move relative to the housing 26 and the second clutch member 36. Similarly, while in the first operating mode OM1, the second clutch member 36 remains stationary. Thus, the driver can rotate the knob 102 to move the shift selector 28 from the home position RH; Rl corresponding to "park" (see Figure 5A) to one of the operational positions RO, such as the operational position RO; R4 corresponding to "drive" (see Figure 6A), or to any other suitable operational position RO; R2, R3. As noted above, while in the operational position RO; R4 corresponding to "drive", the driver can also press the knob 102 to move the shift selector 28 from the first axial position Al (see Figure 6A) to the second axial position A2 (see Figure 6B) in order to subsequently rotate the shift selector to the second operational position RO; R5 corresponding to "sport" (see Figure 6C). [0064] Irrespective of the operational position RO selected by the driver, the shifter assembly 20 is configured to subsequently return the shift selector 28 to the home position RH using rotational torque generated by the motor 30 in the operational condition OC under certain vehicle and transmission 22 operating conditions. To this end, when the clutch mechanism 32 is in the third operating mode OM3, rotation of the motor 30 causes concurrent rotation of the second clutch member 36, the first clutch member 34, and the shift selector 28 to move the shift selector 28 back towards the home position RH. By way of illustrative example, the third operating mode OM3 could be utilized in order to move the shift selector 28 from the second axial position A2 and the second operational position RO; R5 corresponding to "sport" (see Figure 6C) to the first axial position Al and the home position RH; Rl corresponding to "park" (see Figure 7C). Operation of the clutch mechanism 32 in the third operating mode OM3 is best illustrated by comparing the relative location between the reference arrow REF of the second clutch member 36 and the detent plunger 44 of the first clutch mechanism 34 with respect to the housing 26 in Figures 6C-7C. In these Figures, the second clutch member 36 and the shift selector 28 rotate concurrently as rotation of the motor 30 moves the shift selector 28 towards the home position RH.

[0065] In one embodiment, the clutch mechanism 32 moves from the third operating mode OM3 to the second operating mode OM2 in response to a predetermined applied torque acting on the shift selector 28. Put differently, in an absence of torque applied to the knob 102, rotation of the motor 30 in the operational condition OC rotates the first clutch member 34 and the second clutch member 36 concurrently. However, when torque is applied to the knob 102 while the motor 30 is in the operational condition OC, the clutch mechanism 32 will move to the second operating mode OM2 so as to rotate the second clutch member 36 relative to the first clutch member 34. In the representative embodiment illustrated herein, the amount of rotational torque required to move the clutch mechanism 32 from the third operating mode OM3 to the second operating mode OM2 is defined by the engagement of the detent plunger 44 within one of the detents 42, as biased by the detent biasing element 54.

[0066] It will be appreciated that rotational torque applied to the knob 102 during use could result from a number of different circumstances or operating conditions. By way of non-limiting example, if the driver were to grab or attempt to actuate the knob 102 while the shift selector 28 was moving towards the home position RH with the motor 30 in the operational condition OC, the clutch mechanism 32 would move from the third operating mode OM3 to the second operating mode OM2 as a result of the torque applied to the knob 102 from the driver. Similarly, if movement of the knob 102 was somehow restricted in operation, such as by a purse strap inadvertently hung on the knob 102 (not shown), operation of the motor 30 in the operational condition OC would move the clutch mechanism 32 from the third operating mode OM3 to the second operating mode OM2 as a result of the torque applied to the knob 102 from the purse strap. It will be appreciated that this functionality afforded by the clutch mechanism 32 helps prevent inadvertent damage to various components of the shifter assembly 20, such as the motor 30.

[0067] In one embodiment, the motor 30 is configured to remain in the operational condition OC for a predetermined interval after the clutch mechanism 32 moves from the third operating mode OM3 to the second operating mode OM2. Here, the motor 30 may further be configured to move from the operational condition OC to the locked condition LC after the interval is crossed. The interval is based on at least one of time, current flowing through the motor 30, and rotation of the motor 30. Advantageously, because the position of the shift selector 28 is known via the rotational position sensor 74, the electronic control unit 24 can determine when the clutch mechanism 32 is in the second operating mode OM2, such as when predetermined rotation of the motor 30 in the operational condition OC does not result in corresponding predetermined movement of the shift selector 28. In one embodiment, the engagement between the stop member 84 and the gate 82 at the home position RH causes the clutch mechanism 32 to move from the third operating mode OM3 to the second operating mode OM2 in response to abutment between the first stop portion 90 and the first slot end 86. Here, the electronic control unit 24 can similarly determine how to drive the motor 30 based on the relative position of the shift selector 28 as communicated by the rotational position sensor 74.

[0068] As noted above, the shifter assembly 20 returns the shift selector 28 to the home position RH under certain vehicle and transmission 22 operating conditions. Here, it will be appreciated that the electronic control unit 24 could determine the most appropriate mode for the transmission 22 to operate in, based in part on information communicated from one or more occupant sensors, occupant proximity sensors, vehicle operating conditions, and the like. Here, cooperation between the electronic control unit 24 and the shifter assembly 20 allows vehicles to be operated in unconventional ways, such as by enabling the driver to exit the vehicle safely without engaging the shifter assembly 20 to "park" the vehicle, whereby the shifter assembly 20 can return the knob 102 and shift selector 28 to the home position RH without the driver's input. Similarly, the electronic control unit 24 and shifter assembly 20 can control the transmission 22 so as to ensure proper vehicle operation and help prevent vehicle damage. By way of non-limiting example, the electronic control unit 24 could command the shifter assembly 20 to move from "reverse" into "neutral" if the vehicle experiences forward travel at a predetermined speed. It will be appreciated that the functionality afforded by the shifter assembly 20 of the present invention is particularly advantageous in applications where it is desirable for the knob 102 to return to a specific physical orientation or position each time the vehicle is started, such as where the knob 102 has a tactile position indicia (not shown).

[0069] In this way, the shifter assembly 20 of the present invention provides improved functionality and usability in connection with conventional automatic transmission systems and, at the same time, reduces the cost and complexity of manufacturing and assembling shifter assemblies 20. Specifically, it will be appreciated that the clutch mechanism 32 affords opportunities for operating vehicle transmissions 22 in advantageous ways by enabling physical movement of the shift selector 28 and knob 102 without driver actuation. Moreover, those having ordinary skill in the art will appreciate that the clutch mechanism 32 itself biases the shift selector 28 into one of the radial positions and, thus, allows the shifter assembly 20 to be implemented without the use of a discreet biasing mechanism to maintain the rotational position of the shift selector 28.

[0070] The invention has been described in an illustrative manner, and it is to be understood that the terminology which has been used is intended to be in the nature of words of description rather than of limitation. Many modifications and variations of the present invention are possible in light of the above teachings, and the invention may be practiced otherwise than as specifically described.