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. 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 a 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, modern 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, modern 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 support and a shift rod rotatably supported by the support. The shift rod is selectively movable to a plurality of radial positions and is rotatable in both a first direction and a second direction with the second direction being radially opposite of the first direction. The shifter assembly further includes a first track member and a second track member spaced from the first track member. The track members are each in rotational communication with the shift rod for concurrent movement, with the shift rod between the radial positions. A first actuator is assigned to the first track member and has a first engagement element movable between a retracted position spaced from the assigned first track member and an extended position engaging the assigned first track member. A second actuator is assigned to the second track member and has a second engagement element movable between a retracted position spaced from the assigned second track member and an extended position engaging the assigned second track member. The first track member defines a plurality of first detents each having a configuration permitting rotation of the shift rod in the first direction while preventing rotation of the shift rod in the second direction when the first engagement element is in the extended position. The second track member defines a plurality of second detents each having a configuration permitting rotation of the shift rod in the second direction while preventing rotation of the shift rod in the first direction when the second engagement element is in the extended 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 shifter subassembly and an indentation mechanism, and a pair of main housing covers.

[0013] Figure 3 is a front plan view of the main housing, shifter subassembly, and indentation mechanism of Figure 2. [0014] Figure 4 a partially exploded perspective view of the shifter subassembly, main housing, and indentation mechanism of Figures 2 and 3.

[0015] Figure 5 is a perspective view of the shifter subassembly of Figures 2-4.

[0016] Figure 6 is an alternate rotated perspective view of the shifter subassembly of Figure 5.

[0017] Figure 7 is a front plan view of the shifter subassembly of Figures 2-6.

[0018] Figure 8 is a partially exploded view of the shifter subassembly of Figures 2-7 showing first and second actuators, a cartridge, a cartridge cover, and a shift rod.

[0019] Figure 9 is an alternate rotated partially exploded view of the shifter subassembly of Figure 8.

[0020] Figure 10 is an angled perspective view of the shift rod of Figures 8-10 showing first and second track members each having a plurality of detents.

[0021] Figure 11 is a front plan view of the shift rod of Figures 8-10.

[0022] Figure 12 is a perspective view of the shift rod of Figures 8-11 and the first and second actuators of Figures 8 and 9, the actuators each having an engagement element shown in an extended position engaging one of the detents of one of the track members of the shift rod.

[0023] Figure 13 is a perspective view of an alternate embodiment of a shift rod.

[0024] Figure 14A is an enlarged partial perspective view of the shift rod and the first actuator of Figure 12 with the shift rod shown in a first radial position and with the engagement element of the first actuator shown in a retracted position spaced from the detents of the first track member.

[0025] Figure 14B is an alternate view of the shift rod and the first actuator of Figure 14A with the shift rod shown in the first radial position and with the engagement element of the first actuator shown in the extended position against a stop of one of the detents of the first track member.

[0026] Figure 14C is an alternate view of the shift rod and the first actuator of Figure 14B with the shift rod partially rotated clockwise from the first radial position and with a ramp of one of the detents of the first track member urging the engagement element of the first actuator away from the extended position toward the retracted position.

[0027] Figure 14D is an alternate view of the shift rod and the first actuator of Figure 14C with the shift rod partially rotated further clockwise from the first radial position and with the ramp of one of the detents of the first track member further urging the engagement element of the first actuator away from the extended position toward the retracted position.

[0028] Figure 14E is an alternate view of the shift rod and the first actuator of Figure 14D with the shift rod partially rotated still further clockwise from the first radial position and with the engagement element of the first actuator shown urged away from the detents of the first track member.

[0029] Figure 14F is an alternate view of the shift rod and the first actuator of Figure 14E with the shift rod rotated further clockwise from the first radial position to a second radial position with the engagement element of the first actuator shown in the extended position against the stop of another of the detents of the first track member.

[0030] Figure 15A is a schematic representation of the configuration of the first track member and the first actuator as depicted in Figure 14A along with the corresponding relative position of the second track member with respect to the second actuator, with the engagement element of the second actuator shown in the retracted position. [0031] Figure 15B is a schematic representation of the configuration of the first track member and the first actuator as depicted in Figure 14B along with the corresponding relative position of the second track member with respect to the second actuator, with the engagement element of the second actuator shown in the retracted position.

[0032] Figure 15C is a schematic representation of the configuration of the first track member and the first actuator as depicted in Figure 14C along with the corresponding relative position of the second track member with respect to the second actuator, with the engagement element of the second actuator shown in the retracted position.

[0033] Figure 15D is a schematic representation of the configuration of the first track member and the first actuator as depicted in Figure 14D along with the corresponding relative position of the second track member with respect to the second actuator, with the engagement element of the second actuator shown in the retracted position.

[0034] Figure 15E is a schematic representation of the configuration of the first track member and the first actuator as depicted in Figure 14E along with the corresponding relative position of the second track member with respect to the second actuator, with the engagement element of the second actuator shown in the retracted position.

[0035] Figure 15F is a schematic representation of the configuration of the first track member and the first actuator as depicted in Figure 14F along with the corresponding relative position of the second track member with respect to the second actuator, with the engagement element of the second actuator shown in the retracted position.

[0036] Figure 15G is an alternate schematic representation of the track members and the actuators of Figure 15F with the engagement elements of both the first actuator and the second actuator shown in the extended position. DETAILED DESCRIPTION OF THE INVENTION

[0037] 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. More specifically, the shifter assembly 20 cooperates with an automatic transmission 22 (shown schematically in Figure 1 and generally known in the art) 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/or "sport." To that end, the shifter assembly 20 is in electrical communication with one or more electronic control units 24 (shown schematically in Figure 1 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.

[0038] 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 modern automatic that employs one or more electronically and/or hydraulically actuated clutches, or a conventional manual with an automatically actuated clutch.

[0039] 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, four 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.

[0040] Referring now to Figures 2-15G, the shifter assembly 20 of the present invention includes a support 26 and a shift rod 28 rotatably supported by the support 26. The shift rod 28 is selectively moveable between a plurality of radial positions. As shown best in Figures 2 and 4, the shift rod 28 is rotatable about a reference axis 30 in both a first direction, generally indicated at 32, and a second direction, generally indicated at 34. The second direction 34 is radially opposite of the first direction 32. In the representative embodiment illustrated herein, unless otherwise indicated, the first direction 32 corresponds to clockwise rotation of the shift rod 28 about the reference axis 30, and the second direction 34 corresponds to counterclockwise rotation of the shift rod 28 about the reference axis 30. However, those having ordinary skill in the art will appreciate that the first direction 32 and the second direction 34 could be defined in any suitable way without departing from the scope of the present invention. The shifter assembly 20 also includes a first track member, generally indicated at 36, and a second track member, generally indicated at 38. The second track member 38 is spaced from the first track member 36 (see Figure 10), and the track members 36, 38 are each disposed in rotational communication with the shift rod 28 for concurrent movement with the shift rod 28 between the radial positions, as described in greater detail below. The shifter assembly 20 also includes a first actuator, generally indicated at 40, and a second actuator, generally indicated at 42. The first actuator 40 is assigned to the first track member 36 and has a first engagement element 44 movable between a retracted position 44 A spaced from the assigned first track member 36 (see Figures 14A and 15 A), and an extended position 44B engaging the assigned first track member 36 (see Figures 14B and 15B). Similarly, the second actuator 42 is assigned to the second track member 38 and has a second engagement element 46 movable between a retracted position 46 A spaced from the assigned second track member 38 (see Figure 15B), and an extended position 46B engaging the assigned second track member 38 (see Figure 15G). As shown best in Figure 10, the first track member 36 defines a plurality of first detents, generally indicated at 48, each having a configuration permitting rotation of the shift rod 28 in the first direction 32 while preventing rotation of the shift rod 28 in the second direction 34 when the first engagement element 44 is in the extended position 44B. Similarly, the second track member 38 defines a plurality of second detents, generally indicated at 50, each having a configuration permitting rotation of the shift rod 28 in the second direction 34 while preventing rotation of the shift rod 28 in the first direction 32 when the second engagement element 46 is in the extended position 46B. The support 26, shift rod 28, track members 36, 38, actuators 40, 42, engagement elements 44, 46, and detents 48, 50 will each be described in greater detail below.

[0041] The support 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 illustrated throughout the Figures, the support 26 includes a main housing body 52, front and rear covers 54A, 54B, and a pair of interlocking cartridge elements 56A, 56B. As shown in Figures 4-9, the cartridge elements 56A, 56B support the shift rod 28 and actuators 40, 42 so as to define a shifter sub-assembly, generally indicated at 57. 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 support 26 could be formed from any suitable number of elements, or from a single element, without departing from the scope of the present invention. Further, the main housing body 52 may be of any suitable configuration.

[0042] As shown in Figures 2 and 3, in one embodiment, the shifter assembly 20 includes an indentation mechanism, generally indicated at 58, that cooperates with the shift rod 28 so as to define the plurality of radial positions. To that end, the indentation mechanism 58 includes a wheel 60 and a spring-loaded plunger 62. The wheel 60 is supported in rotational communication with the shift rod 28 and has a plurality of radially-spaced indentations 64 each representing respective radial positions of the shift rod 28. The spring-loaded plunger 62 selectively engages one of the indentations 64 so as to at least partially resist rotation of the shift rod 28. Thus, the plunger 62 holds the shift rod 28 in the respective radial position until the driver applies enough rotational torque to overcome the plunger 62 and move the shift rod 28 to the adjacent radial position. In the representative embodiment illustrated herein, the wheel 60 includes eighteen indentations 64 each having a curved, tapered, and angled profile (see Figures 2 and 3). However, those having ordinary skill in the art will appreciate that the wheel 60 could have any number of indentations 64 with any suitable shape, profile, or configuration, without departing from the scope of the present invention. Moreover, while a single indentation mechanism 58 with a single plunger 62 is utilized in the representative embodiment illustrated herein, those having ordinary skill in the art will appreciate that any suitable number of indentation mechanisms 58, configured in any suitable way, could be utilized without departing from the scope of the present invention. By way of non-limiting example, a plurality of plungers 62 could be utilized.

[0043] As shown best in Figure 3, the spring-loaded plunger 62 is operatively attached to the support 26. More specifically, the spring-loaded plunger 62 is fixed to the main housing body 52 of the support 26 by a pair of screws 66 and is concealed by the front cover 54A (compare Figures 1 and 2). However, it will be appreciated that the plunger 62 could be operatively attached to any part of the shifter assembly 20, in any suitable way sufficient to engage the wheel 60 as discussed above, without departing from the scope of the present invention.

[0044] In the representative embodiment illustrated herein, the shifter assembly 20 also includes a disc 68 disposed in rotational communication with the shift rod 28 for concurrent movement between the radial positions, and the track members 36, 38 are coupled to the disc 68 (see Figure 10). More specifically, the disc 68, the shift rod 28, the first track member 36, and the second track member 38 are formed integrally as a single component. However, as will be appreciated from the subsequent description below, the disc 68 could be formed as a separate component from the shift rod 28 and could otherwise be coupled to the shift rod 28 in any suitable way without departing from the scope of the present invention. Moreover, while the track members 36, 38 each have a substantially annular profile, are aligned substantially concentrically with the shift rod 28, and are formed integrally with the disc 68 (see Figure 10), those having ordinary skill in the art will appreciate that the first track member 36 and/or the second track member 38 could be formed differently and could be arranged, aligned, or configured in any suitable way sufficient to rotate concurrently with the shift rod 28 between the radial positions, without departing from the scope of the present invention. By way of non- limiting example, the first track member 36 and the second track member 38 could each be coupled to discrete discs each disposed in rotational communication with the shift rod 28 (not shown, but generally known in the related art).

[0045] As noted above, the wheel 60 is in rotational communication with the shift rod 28, whereby rotation of the shift rod 28 is concurrent with rotation of the wheel 60. In the representative embodiment illustrated herein, the wheel 60 is mounted to the shift rod 28 which, in turn, is directly fixed to and concentrically aligned with the first track member 36 and the second track member 38 for direct rotational movement therewith, as noted above. The wheel 60 and shift rod 28 are mounted to one another via a spline arrangement, generally indicated at 70. The spline arrangement 70 simplifies the process of assembling the shifter assembly 20 and, at the same time, ensures angular correspondence between the wheel 60 and the shift rod 28. Moreover, the spline arrangement 70 also ensures angular correspondence between the wheel 60 and track members 36, 38. However, it will be appreciated that the shift rod 28, disc 68, track members 36, 38, and/or wheel 60 could be formed from any suitable number of components that cooperate or otherwise interlock in any suitable way, with or without the use of the spline arrangement 70, without departing from the scope of the present invention. [0046] In the representative embodiment of the shifter assembly 20 illustrated throughout the Figures, the shift rod 28, the disc 30, and the wheel 60 are all concentrically aligned with one another and rotate together in response to rotational torque applied to the shift rod 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 72 attached to the shift rod 28 (see Figures 1 and 2). In operation, the driver rotates the knob 72 which, in turn, rotates the shift rod 28, the track members 36, 38, and the wheel 60. While the shift rod 28, track members 36, 38, wheel 60, and knob 72 are all concentrically aligned about the reference axis 30, it will be appreciated that the shift rod 28, track members 36, 38, and/or knob 72 could be oriented differently with respect to each other and/or the wheel 60 without departing from the scope of the present invention. By way of non-limiting example, the knob 72, shift rod 28, and track members 36, 38 could be spaced from the wheel 60, and the shifter assembly 20 could employ a geartrain (not shown, but generally known in the art) to effect rotational communication between the disc 30 and wheel 60. Similarly, the knob 72 could be spaced from and be in rotational communication with the shift rod 28 without departing from the scope of the present invention. Further, as noted above, the first track member 36 and the second track member 38 could be supported differently without departing from the scope of the present invention, such as at a 94- degree relative rotational angle with respect to each other and/or the shift rod 28 (not shown, but generally known in the art).

[0047] Referring now to Figures 4-9 and 12-15G, as noted above, the shifter assembly 20 of the present invention includes a pair of actuators 40, 42 for selectively engaging their assigned track member 36, 38. Specifically, the first engagement element 44 of the first actuator 40 engages one of the first detents 48 of the first track member 36 when the first engagement element 44 of the first actuator 40 is in the extended position 44B, and the second engagement element 46 of the second actuator 42 engages one of the second detents 50 of the second track member 38 when the second engagement element 46 of the second actuator 42 is in the extended position 46B. The actuators 40, 42 are supported in the support 26 adjacent to their respectively assigned track member 36, 38. More specifically, the actuators 40, 42 are secured between the cartridge elements 56A, 56B (see Figures 8 and 9) which, in turn, are disposed in the main housing body 52 of the support 26. However, those having ordinary skill in the art will appreciate that the actuators 40, 42 could be secured differently, with or without the use of the cartridge elements 56A, 56B, without departing from the scope of the present invention. In one embodiment, the actuators 40, 42 are realized as electromagnetically actuated solenoids, whereby electric current is used to selectively move the engagement elements 44, 46 of the respective actuators 40, 42 between the positions 44A, 44B, 46A, 46B, as discussed above. The actuators 40, 42 can be design as passive or active actuators / solenoids as known to those skilled in the art. In other words, one or both of the engagement elements 44, 46 may be in the extended positions 44B, 46B when in a rest, or passive, condition. Alternatively, one or both of the engagement elements 44, 46 may be in the retracted positions 44A, 46A, when in a rest, or passive, condition. As is also appreciated by those skilled in the art, the actuators 40, 42 may be disposed in electrical communication with the electronic control unit 24 (connection not shown in detail, but generally known in the art) for selectively and independently moving the engagement elements 44, 46 between the positions 44A, 44B, 46A, 46B. However, it will be appreciated that the actuators 40, 42 could be of any suitable type or configuration sufficient to move engagement elements 44, 46 into engagement with the respectively assigned track member 36, 38 and could be actuated in any suitable way, without departing from the scope of the present invention.

[0048] As shown best in Figure 11, in one embodiment, the first track member 36 is arranged about a first reference circle 74 having a first diameter, and the second track member 38 is arranged about a second reference circle 76 having a second diameter different from the first diameter. More specifically, the second diameter is greater than the first diameter. However, those having ordinary skill in the art will appreciate that the first reference circle 74 and/or the second reference circle 76 could have any suitable diameter without departing from the scope of the present invention. The first reference circle 42 and the second reference circle 44 are both aligned in a common reference plane 78 (see Figure 11) and are concentrically aligned with the shift rod 28.

[0049] In the representative embodiment illustrated throughout the figures, the disc 68 has opposing first and second surfaces 80, 82 with the first surface 80 of the disc 68 facing towards the engagement elements 44, 46 of the actuators 40, 42. Here, the first surface 80 of the disc 68 defines the common reference plane 78, and the first track member 36 and the second track member 38 are coplanar with the common reference plane 78 (see Figure 10). The first engagement element 44 and the second engagement element 46 each have a substantially cylindrical profile and each extend to a respective engagement element end, generally indicated at 88. In the representative embodiment illustrated herein, the first actuator 40 and the second actuator 42 are the same size, type, and configuration, and are both supported in the support 26 at a substantially equal distance from the first surface 80 of the disc 68. Moreover, the actuators 40, 42 are supported and aligned such that the engagement elements 44, 46 are both substantially parallel to the shift 28. Thus, the engagement elements 44, 46 move between the positions 44A, 44B, 46 A, 46B in a direction substantially parallel to the reference axis 30 about which the shift rod 28 rotates. However, as noted above, the first track member 36, the second track member 38, the first actuator 40, and/or the second actuator 42 could be aligned, arranged, supported, or otherwise configured in any suitable way so as to selectively limit rotation of the shift rod 28 between the radial positions, as described above, without departing from the scope of the present invention.

[0050] As best depicted by the schematic representation of in Figures 15A-15G, when in the retracted position 44A, 46A, the engagement elements 44, 46 are spaced from the first surface 80 of the disc 68 (see Figure 15A). Further, when in the extended position 44B, 46B, the engagement elements 44, 46 are disposed in one of the respective detents 48, 50 of the assigned track member 36, 38 (see Figure 15G). Here, in the extended position 44B, 46B, the engagement elements 44, 46 are spaced between the first surface 80 of the disc 68 and the second surface 82 of the disc 68. Thus, in the embodiment of the disc 68 illustrated in Figures 4-12 and 14A-14F, each of the detents 48, 50 extends between the first surface 80 of the disc 68 and the second surface 82 of the disc 68. However, in the alternate embodiment illustrated in Figure 13, the disc 68 also includes a floor, generally indicated at 83, extending from the second surface 82 of the disc 68 toward the first surface 80 of the disc 68. Here, the detents 48, 50 of the track members 36, 38 are arranged, aligned, and sized differently (compare Figure 13 to Figure 11), and also extend from the first surface 80 of the disc 68 to the floor 83 of the disc 68. It will be appreciated that the engagement elements 44, 46 could either abut or otherwise engage the floor 83 of the disc 68 when in the extended position 44B, 46B, or could otherwise be spaced from the floor 83 of the disc 68 when in the extended position 44B, 46B, without departing from the scope of the present invention. [0051] Referring now to Figures 10-12 and 14A-15G, as noted above, the track members 36, 38 each include a respective plurality of detents 48, 50 for cooperating with the engagement elements 44, 46 of the actuators 40, 42, as described above. In one embodiment, each of the track members 36, 38 includes an identical quantity of detents 48, 50. More specifically, in the representative embodiment illustrated throughout the figures, the track members 36, 38 each include eighteen detents 48, 50. As shown in Figure 11, the first detents 48 of the first track member 36 have a first arc length 84 and the second detents 50 of the second track member 38 have a second arc length 86 different from the first arc length 84. More specifically, the second arc length 86 of the second detents 50 is greater in magnitude than the first arc length 84 of the first detents 48. Further, each of the first detents 48 has a substantially equivalent first arc length 84, and each of the second detents 50 has a substantially equivalent second arc length 86. Further, as best shown in Figure 11, the first detents 48 of the first track member 36 are spaced equally from each other, are radially aligned about the first reference circle 74, and have a closed periphery. Similarly, the second detents 50 of the second track member 38 are spaced equally from each other, are radially aligned about the second reference circle 76, and have a closed periphery. However, those having ordinary skill in the art will appreciated that the detents 48, 50 could be arranged, aligned, or otherwise configured in any suitable way sufficient to cooperate with the actuators 40, 42 to facilitate selective rotational blocking of the shift rod 28, as described above, without departing from the scope of the present invention.

[0052] As noted above, the detents 48, 50 cooperate with the engagement elements 44, 46 so as to selectively and independently prevent rotation of the shift rod 28 between the radial positions in the first direction 32 and/or in the second direction 34. To that end, in the representative embodiment illustrated herein, each of the first detents 48 of the first track member 36 has a first stop 88, and each of the second detents 50 of the second track number 38 has a second stop 90. The first stops 88 of the first detents 48 of the first track member 36 are arranged such that one of the first stops 88 abuts the first engagement element 44 in the extended position 44B in response to rotation of the shift rod 28 in the second direction 34 so as to prevent rotation of the shift rod 28 in the second direction 34 (see Figures 14B and 15B). Similarly, the second stops 90 of the second detents 50 of the second track member 38 are arranged such that one of the second stops 90 abuts the second engagement element 46 in the extended position 46B in response to rotation of the shift rod 28 in the first direction 32 so as to prevent rotation of the shift rod 28 in the first direction 32 (see Figure 15G). The stops 88, 90 of the track members 36, 38 are arranged such that rotation of the shift rod 28 is prevented when both of the engagement elements 44, 46 are in the second position 44B, 46B (see Figure 15G). Similarly, the first stops 88 of the first track member 36 are spaced from the first engagement element 44 in the retracted position 44A, the second stops 90 of the second track member 38 are spaced from the second engagement element 46 in the retracted position 46A. Moreover, the track members 36, 38 are arranged with respect to the actuators 40, 42 such that the shift rod 28 can freely rotate in the first direction 32 and also in the second direction 34 between the radial positions when both of the engagement elements 44, 46 are in the retracted position 44A, 46A (see Figure 15A).

[0053] In one embodiment, the stops 88, 90 each include a vertical stop wall, generally indicated at 91. The vertical stop walls 91 each have a substantially curved profile and are aligned substantially parallel with the reference axis 30 of the shift rod 28. As noted above, the engagement elements 44, 46 each have a substantially curved profile with a first radius 92 (see Figure 7). In one embodiment, the curved profile of the vertical stop walls 91 each have a second radius 94 that is greater than the first radius 92 of the engagement elements 44, 46. It will be appreciated that this arrangement helps prevent interference between the engagement elements 44, 46 and the track members 36, 38 in operation.

[0054] As noted above, the detents 48, 50 cooperate with the engagement elements 44, 46 so as to selectively and independently permit limited rotation of the shift rod 28 between the radial positions in the first direction 32 and/or in the second direction 34. To that end, in the representative embodiment illustrated herein, each of the first detents 48 of the first track member 36 has a first ramp 96, and each of the second detents 50 of the second track number 38 has a second ramp 98. The first ramps 96 of the first detents 48 of the first track member 36 are arranged so as to urge the first engagement element 44 away from the extended position 44B toward the retracted position 48A in response to rotation of the shift rod 28 in the first direction 32 so as to permit rotation of the shift rod 28 in the first direction 32 (compare Figures 14B-14E and 15B-15E). Similarly, the second ramps 98 of the second detents 50 of the second track member 38 are arranged so as to urge the second engagement element 46 away from the extended position 46B toward the retracted position 46A in response to rotation of the shift rod 28 in the second direction 34 (not shown in detail) so as to permit rotation of the shift rod 28 in the second direction 34. Thus, the ramps 96, 98 are configured to urge the respective engagement elements away from the extended position 44B, 46B and toward the retracted position 44A, 46B, as noted above. However, the ramps 96, 98 do not necessarily urge the respective engagement elements 44, 46 all the way to the retracted positions 44A, 44B. Rather, as shown in Figure 15E and as is described in greater detail below, the ramps 96, 98 could urge the engagement elements 44, 46 to an intermediate position defined against the first surface 80 of the disc 68 between the detents 48, 50 of the track members 36, 38 as the shift rod 28 rotates between the discrete radial positions. Thus, the intermediate position of the first engagement element 44 shown in Figure 15E is not necessarily the retracted position 44A as shown in Figure 15A (compare the relative position of the engagement element 44 in Figures 15E and 15A).

[0055] As best shown in Figures 14A-15G, the ramps 96, 98 each have a respective ramp surface 100 with a substantially linear profile configured to urge the engagement elements 44, 46 away from the extended position 44B, 46B, as noted above. However, those having ordinary skill in the art will appreciate that the ramp surfaces 100 could have any suitable profile or configuration sufficient to urge the engagement elements 44, 46 as described above without departing from the scope of the present invention. The first ramps 96 of the first detents 48 of the first track member 36 are each defined at a first angle 102 with respect to the first stops 88 of the first track member 36, and the second ramps 98 of the second detents 50 of the second track member 38 are each defined at a second angle 104 with respect to the second stops 90 of the second track member 38 (see Figure 15 A). In the representative embodiment illustrated herein, the first angle 102 is substantially equal in magnitude to the second angle 104. It will be appreciated that this configuration effects substantially equivalent rotational haptic feedback in both rotational directions 32, 34 as the knob 72 is rotated.

[0056] As noted above, Figures 14A-14F show enlarged perspective views of various progressive radial positions of the shift rod 28 adjacent to the first engagement element 44 of the first actuator 40 which, in turn, is shown adjacent to the first detents 48 of the first track member 36. Similarly, Figures 15A-15F depict schematic representations of the relative positions of both of the track members 36, 38 and both of the engagement elements 44, 46. Further, the schematic representations of the first engagement element 44 and the first track member 36 depicted in Figures 15A-15F each correspond the relative positions of the first engagement element 44 and the first track member 36 shown in Figures 14A-14F, respectively. For the purposes of clarity and consistency, one of the first detents 48 is labeled as 48REF in Figures 14A-15F so as to help demonstrate the relative movement of the track members 36, 38 with respect to the assigned actuator 40, 42, as described in greater detail below. Thus, movement of the track members 36, 38 can be observed by sequentially comparing the relative position of the detent 48REF as shown in Figures 14A through 14F (and Figures 15A through 15F).

[0057] It will be appreciated that the track members 36, 38 move with the shift rod 28 as the driver rotates the knob 72 to select between operating modes of the transmission 22, as discussed above. Further, because of how the detents 48, 50 and the actuators 40, 42 are arranged, the engagement elements 44, 46 are each able to move to the extended position 44B, 46B when the shift rod 28 is in one of the discreet radial positions, as described above. Thus, when the shift rod 28 is in one of the discrete radial positions, the actuators 40, 42 can be selectively and independently moved between the retracted position 44A, 46A and the extended position 44B, 46B so as to effect selective rotational blocking of the shift rod 28 in either or both of the rotational directions 32, 34, irrespective of which discrete radial position the shift rod 28 is in. More specifically, when the shift rod 28 is in one of the discrete radial positions, both of the engagement elements 44, 46 can be selectively brought into abutment with one of the stops 88, 90 of the detents 48, 50. Thus, it is possible to limit rotation of the shift rod 28 to a specific and predetermined number of radial positions in either or both rotational directions 32, 34 by selectively controlling the relative position 44A, 44B, 46A, 46B of the engagement elements 44, 46, as discussed in greater detail below.

[0058] It will be appreciated that the configuration of the shifter assembly 20 discussed above enables so-called "infinite turn" functionality, whereby the shift rod 28 can rotate 365- degrees in either direction 32, 34 when both engagement elements 44, 46 are in the retracted position 44A, 44B spaced from the respectively assigned track member 36, 38. By selectively blocking rotation of the shift rod 28 between specific predetermined radial positions, the shifter assembly 20 can also be configured so as to prevent the driver from selecting inappropriate operating modes of the transmission 22 during vehicle operation. By way of non-limiting example, the electronic control unit 24 could be configured to control the actuators 40, 42 of the shifter assembly 20 so as to prevent the driver from selecting "reverse" when the vehicle is moving in a forward direction with the transmission 22 operating in "drive" mode.

[0059] Taken together, the infinite turn functionality of the shift rod 28 and selective rotation blocking via the actuators 40, 42 provide additional opportunities for enhanced functionality of the shifter assembly 20 in operation. To that end, each of the actuators 40, 42 may be sequentially activated by the electronic control unit 24 in predetermined ways so as to enable movement between predetermined driving modes of operating the transmission 22. In the representative embodiment illustrated herein, four different operating modes are provided for: "park," "reverse," "neutral," and "drive," each of which can be selected during vehicle operation. Moreover, the actuators 40, 42 can cooperate with the electronic control unit 24 so as to effect changing between transmission 22 operating modes irrespective of the physical radial position of the shift rod 28. Thus, it will be appreciated that the actuators 40, 42A can be controlled so as to facilitate movement to a different operating mode when the vehicle is shut off or re-started, irrespective of the physical radial position of the shift rod 28 and also irrespective of the operating mode the transmission 22 was left in. By way of illustration, it is conceivable that the driver could exit the vehicle without switching the shifter assembly 20 from "drive" into "park". In such a situation, the electronic control unit 24 could be configured to determine that the vehicle -should- be parked (such as via signals from an ignition key removal sensor or a driver proximity sensor; not shown, but known in the art) and could subsequently move the transmission 22 from "drive" into "park." The actuators 40, 42A, could then be subsequently controlled such that the physical orientation of the shift rod 28 need not change when the vehicle is re-started.

[0060] By way of further illustration, the configuration shown in Figure 15A could correspond to a vehicle that is powered off with the transmission 22 in "park". In this configuration, the shift rod 28 can be freely rotated in either direction 32, 34. Alternatively, the configuration shown in Figure 15G could also be utilized when the vehicle is powered off with the transmission 22 in "park" so as to prevent any inadvertent rotation of the shift rod 28 in either direction 32, 34. Regardless, once the driver enters and powers on the vehicle, the electronic control unit 24 could ensure that both of the engagement elements 44, 46 are moved to the extended position 44B, 46B (see Figure 15G) so as to prevent any rotation of the shift rod 28 until certain predetermined vehicle operating conditions are met. For example, the electronic control unit 24 could hold both of the engagement elements 44, 46 in the extended position 44B, 46B until the electronic control unit 24 determines that the driver has pressed a brake pedal, such as via a brake pedal position sensor (not shown, but generally known in the related art).

[0061] Subsequently, the electronic control unit 24 could move the second engagement element 46 to the retracted position 46A and simultaneously hold the first engagement element 44 in the extended position 44B (see Figure 15B). Here, as shown in Figure 15B, the first engagement element 44 is abutting the first stop 88 of the reference first detent 48REF of the first track member 36 thereby preventing rotation of the shift rod 28 in the second direction 34, and the second engagement element 46 is spaced from the second track member 38 out of abutment with the second stops 90 of the second detents 50 thereby not blocking rotation of the shift rod 28 in the first direction 32. Put differently, in the configuration shown in Figure 15B, the shift rod 28 can only be rotated in the first direction 32.

[0062] Continuing with the illustrative example introduced above, the configuration shown in Figure 15B could be utilized when the brake pedal is depressed, as noted above, and until the shift rod 28 is rotated in the first direction 32 to the adjacent radial position, as is progressively illustrated in Figures 15B to 15F. Here, as the shift rod 28 is rotated in the first direction 32 from the configuration shown in Figure 15B to the configuration shown in Figure 15C, the first ramp 96 of the reference first detent 48REF begins to urge the first engagement element 44 away from the extended position 44B. As the shift rod 28 continues to rotate further in the first direction 32, the first ramp 96 of the first detent 48REF urges the first engagement element 44 even further away from the extended position 44B, as shown in Figure 15D (compare Figure 15D to Figure 15C).

[0063] As the shift rod 28 continues to rotate still even further in the first direction 32, the first ramp 96 of the reference first detent 48REF urges the first engagement element 44 still even further away from the extended position 44B until the first engagement element 44 comes out of contact with the first ramp 96 of the reference first detent 48REF, as shown in Figure 15E (compare Figure 15E to Figure 15D).

[0064] Subsequently, as the shift rod 28 continues to rotate even further in the first direction 32, the first detent 48A adjacent to the reference first detent 48REF becomes aligned with the first engagement element 44 such that the first engagement element 44 returns to the extended position 44B engaging in the first detent 48 A adjacent to the reference first detent 48REF, as shown in Figure 15F (compare Figure 15F to Figure 15E). [0065] Continuing with the illustrative example introduced above, once the first detent 48 A adjacent to the reference first detent 48REF is engaged, the electronic control unit 24 could move the transmission to the "reverse" operating mode. The electronic control unit 24 could then be configured to control engagement elements 44, 46 of the shifter assembly 20 in predetermined ways so as to facilitate operator selection of only certain predetermined transmission 22 operating modes based on vehicle operating conditions and the current operating mode. By way of example, when the transmission 22 is in the "reverse" operating mode, the electronic control unit 24 could control the shifter assembly 20 so as to enable the driver to select either the "neutral" operating mode by continued rotation of the shift rod 28 in the first direction 32 to the adjacent radial position, or enable the driver to return to the "park" operating mode by rotation of the shift rod 28 in the second direction 34. Likewise, the electronic control unit could allow the driver to move from the "neutral" operating mode to the "drive" operating mode by continued rotation of the shift rod 28 in the first direction 32, or enable the driver to return to the "reverse" operating mode by rotation of the shift rod 28 in the second direction 34.

[0066] 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.

[0067] 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.