Abstract:
A park lock of a transmission, including a park gear; a park pawl rotating about a pawl shaft, the park pawl having a pawl portion locking the park gear, the park pawl including a cam contact portion; a park rod responsive to an operation of a controller, the park rod having a cam portion pressing the cam contact portion to have park pawl engage the park gear; a park sleeve receiving the cam portion and defining a first contact point providing a reactive force to the cam contact portion of the park pawl pressing against the cam portion at a second contact point; a pawl torsional spring biasing the park pawl towards disengagement; and a pawl stopper limiting the rotation of the park pawl wherein motions are constrained within a plane of the transmission and components are rotatingly disposed in parallel axis bores in one half of a transmission case.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    The present invention relates generally to mechanical park locking for vehicle transmissions, and more specifically, but not exclusively, to a park lock mechanism for narrow transmissions having tight packaging and weight constraints. 
         [0002]    Park lock devices for automotive vehicle transmissions are notoriously well known as a general proposition. Transmissions have continued to evolve, and park lock devices disposed within such transmissions also need to evolve. For example, a particular transmission for an electric vehicle (EV) is quite narrow as it is positioned between an electric motor on one side and an inverter on the other side. Where many conventional park lock devices are implemented in two planes, a narrow transmission of an electric vehicle prevents implementation of such conventional solutions. Further, many conventional park lock devices include a park lock controller near the parking gear. The narrow transmission having large areas covered by the motor on one side and the inverter on the other limits such conventional location of the park lock controller. 
         [0003]    Mechanical cooperation of the components of such transmissions preferably meet a number of operational goals in addition to provision of a park mode and a not parked mode. These operational goals in some cases are actual requirements and include resistance to park engagement while the vehicle is moving. As soon as the speed of the vehicle falls below the lock speed while park mode is commanded, the park lock device should automatically engage to safely enter into the park mode and stop the vehicle. The transmission should then remain parked until the vehicle is transitioned to the not parked mode. Irrespective of a slope on which the EV is stopped, the transmission should not provide too great of mechanical resistance to mode transition. 
         [0004]    While not necessarily required by the narrowness of the EV transmission, systems on EVs have tight budgets for space and weight. These budget constraints work against a straight-forward implementation of a park lock device for a narrow transmission such as may be contemplated to be used in an EV. What is needed is a system and method for a park lock mechanism for narrow transmissions having tight packaging and weight constraints. 
       BRIEF SUMMARY OF THE INVENTION 
       [0005]    Disclosed is a system and method for a park lock mechanism for narrow transmissions having tight packaging and weight constraints. A novel architecture reduces part count to implement a robust one-dimensional remotely-actuated self-aligning park lock device in a narrow transmission that is appropriate for use in an electric vehicle or the like. 
         [0006]    The following summary of the invention is provided to facilitate an understanding of some of technical features related to narrow transmission park lock devices, and is not intended to be a full description of the present invention. A full appreciation of the various aspects of the invention can be gained by taking the entire specification, claims, drawings, and abstract as a whole. The present invention is applicable to other transmission systems other than electric passenger vehicles. 
         [0007]    A park lock device of a narrow transmission includes a park gear provided in a transmission case at a rotational axis which rotates together with a wheel axle; a park pawl provided in the transmission case so as to rotate about a pawl shaft coupled to a proximal end of the park pawl, the park pawl having a pawl portion at a distal end which locks the park gear through an engagement therebetween wherein the park pawl further includes a body portion coupling the proximal end to the distal end and a cam contact portion at the distal end opposing the pawl portion; a park rod provided in the transmission case so as to move together with an operation of a controller, the park rod having a cam portion which presses the cam contact portion of the park pawl so as to make the engagement between the pawl portion of the park pawl and the park gear according to the operation of the controller; a park sleeve receiving the cam portion of the park rod and defining a first contact point providing a reactive force to the cam contact portion of the park pawl pressing against the cam portion of the park rod at a second contact point; a pawl torsional spring, coupled to the pawl shaft, biasing a rotation of the park pawl about the pawl shaft towards a disengagement of the park gear and the pawl portion to unlock the park gear; and a pawl stopper provided in the transmission case to limit the rotation of the park pawl by contacting the body portion of the park pawl; wherein motion of the park gear, the park pawl, and the park rod are constrained within a vertical plane of the transmission case. 
         [0008]    A park lock method for a narrow transmission case, the method responsive to a controller to selectively engage a park gear provided for rotation in a plane of the narrow transmission case at a rotational axis which rotates together with a wheel axle, the method including a) moving, within the plane of the narrow transmission case, a park rod together with an operation of the controller remotely disposed from the park gear, the park rod including a cam portion; b) pressing the cam portion against a cam contact portion of a park pawl disposed within the narrow transmission case to engage the park gear when the operation of the controller commands a park mode, the park pawl rotatable within the plane about a pawl shaft disposed at a proximal end of the park pawl with the park pawl including a pawl portion at a distal end that engages the park gear in the park mode wherein the cam contact portion is also disposed at the distal end opposing the pawl portion and interacts with the cam portion within a self-aligning rotatable park sleeve; c) releasing the cam portion from the cam contact portion of the park pawl to disengage the park gear when the operation of the controller commands a not park mode; and d) rotating the park pawl to disengage the pawl portion from the park gear responsive to a disengagement-biasing torsional spring coupled to the pawl shaft after the cam portion has been released from the cam contact portion wherein a self-aligning pawl stopper is rotatably disposed proximate a body portion of the park pawl to limit disengaging rotation of the park pawl with the body portion joining the proximal end to the distal end. 
         [0009]    There are a number of features, benefits, and advantages of the present invention, with implementations of the present invention including reduced stresses and fewer mounting requirements for the park lock device components. Some features include including use of a self-aligning park sleeve that does not experience any net moment under parked load, a bracket simply retains both the park sleeve and pawl stopper within alignment limits, and provides safe operation in a parked mode and a not parked mode. 
         [0010]    Other features, benefits, and advantages of the present invention will be apparent upon a review of the present disclosure, including the specification, drawings, and claims. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0011]    The accompanying figures, in which like reference numerals refer to identical or functionally-similar elements throughout the separate views and which are incorporated in and form a part of the specification, further illustrate the present invention and, together with the detailed description of the invention, serve to explain the principles of the present invention. 
           [0012]      FIG. 1  illustrates a side view of a narrow transmission including a park lock device, the park lock device in a “not parked” mode; 
           [0013]      FIG. 2  illustrates a side view of the narrow transmission illustrated in  FIG. 1  with the park lock device in a “parked” mode; 
           [0014]      FIG. 3  illustrates a sectional view of a portion of the park lock device of  FIG. 1  depicting an interaction of the park rod and the park pawl inside the park sleeve; 
           [0015]      FIG. 4  illustrates a sectional view of a portion of the park lock device of  FIG. 2  depicting an interaction of the park rod and the park pawl inside the park sleeve; 
           [0016]      FIG. 5  illustrates a sectional view of a portion of the park lock device detailing a transition between the parked mode and the not parked mode; 
           [0017]      FIG. 6  illustrates a sectional view of a portion of the park lock device detailing an operational mode with a controller in parked position prior to the parking pawl engaging the park gear; 
           [0018]      FIG. 7  illustrates a side view of the park rod; 
           [0019]      FIG. 8  illustrates a top view of the park rod; 
           [0020]      FIG. 9  illustrates a sectional view of a mid-portion of the park rod; 
           [0021]      FIG. 10  illustrates a top view of the park lock device components from  FIG. 2  (park mode) isolated from the transmission case; 
           [0022]      FIG. 11  illustrates a side view of the park lock device components of  FIG. 10 ; 
           [0023]      FIG. 12  illustrates an end view of the parking sleeve detailing an opening receiving the cam portion of the parking rod; and 
           [0024]      FIG. 13  illustrates an isometric view of the parking sleeve including receipt of the cam portion. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0025]    Embodiments of the present invention provide a system and method for a park lock mechanism for narrow transmissions having tight packaging and weight constraints. The following description is presented to enable one of ordinary skill in the art to make and use the invention and is provided in the context of a patent application and its requirements. 
         [0026]    Various modifications to the preferred embodiment and the generic principles and features described herein will be readily apparent to those skilled in the art. Thus, the present invention is not intended to be limited to the embodiment shown but is to be accorded the widest scope consistent with the principles and features described herein. 
         [0027]      FIG. 1  illustrates a side view of a narrow transmission  100  including a park lock device, the park lock device in a “not parked” mode or position, and  FIG. 2  illustrates a side view of narrow transmission  100  including the park lock device in a “parked” mode or position. The park lock device is a mechanical interlock that selectively engages with and disengages from a park lock gear  105 . Park lock gear  105  includes a rotational axis A which rotates together with a motor axis M within a transmission case, motor axis M coupled in turn to a wheel axis of a vehicle. The transmission case includes a pair of complementary mating half cases, a back half case  110  shown in  FIG. 1 . 
         [0028]    The park lock device includes a cooperating set of components: a park pawl  115 , a park rod  120 , a park sleeve  125 , a pawl torsional spring  130 , and a pawl stopper  135 . These components move within a single plane defined by the transmission case and are supported by the transmission case as further described herein. 
         [0029]    Park lock gear  105  includes an outside diameter perimeter having a number N of distributed uniform concave portions  140 . Concave portions  140  cooperate with a pawl portion  145  of park pawl  115  for producing the modes described herein, those modes including the parked mode and the not parked mode. Park pawl  115  rotates about a pawl shaft  150  when pawl portion  145  engages with, and disengages from, concave portions  140 . 
         [0030]    The engaging/disengaging rotation of park pawl  115  is initiated by a movement of park rod  120 . As further detailed below, park rod  120  and park pawl  115  make contact inside of park sleeve  125 , with the consequence that the park lock device enters into one of its modes (as further determined by the operational state of the other components of narrow transmission  100 ). 
         [0031]    The movement of park rod  120  is responsive to a controller (not shown) that commands one of the parked mode and the not parked mode for narrow transmission  100 . While there are many types of controllers, in the present example, a software-controlled electromagnetic rotary actuator controls a rotation of a control shaft  155 . Control shaft  155  rotates between a not parked position (in  FIG. 1 ) and a parked position ( FIG. 2 ). Control shaft  155  rotates when making these transitions between parked and not parked positions, however due to the nature of such electromechanical actuators, control shaft  155  sometimes does not exactly rotate. 
         [0032]    Narrow transmission  100  compensates for any inexact rotation by mechanically limiting/finishing rotation of control shaft  155  by use of a detent plate  160 . Detent plate  160  includes a cam profile with two detents, one detent corresponding to the park position and one detent corresponding to the not parked position. The cam profile includes a number of curves and slopes joining the two detents. A detent spring  165  includes a cam profile follower  170  that limits any over rotation of control shaft  155  in both rotational directions due to physical stops at outside edges of the detents. Cam profile follower  170  inhibits any under rotation of control shaft  155  in both directions by either finishing a rotational transition or returning control shaft to its pre-transition position. The specifics are determined by the amount of actual rotation of control shaft  155  and where cam profile follower  170  is placed along the cam profile. 
         [0033]    Detent spring  165  exerts sufficient torque on control shaft  155  through interaction with detent plate  160  to follow the cam profile and rotate control shaft  155  until cam profile follower  170  engages one of the two detents. A required torque to actuate parked mode from not parked mode is kept below a minimum torque provided by detent plate  160  and interacting detent spring  165 . In the embodiment of  FIG. 1 , the cam profile is not symmetric having a different set of conditions to transition from parked to not parked as compared to a set conditions to transition from not parked to parked. The curves and slopes of the cam profile are configured to provide the desired response to rotational uncertainty in control shaft  155  and a required amount of torque for detent spring  165  for those desired responses. 
         [0034]    Due to tight packaging requirements in the transmission case, detent spring  165  is a leaf spring mounted laterally from back half case  110  using a support  175  rather than having detent spring  165  mounted directly to the transmission case on the top or bottom surface of the spring in a conventional fashion. The particular configuration of detent spring  165  provides the necessary torques for cam profile follower  170  to affect movement of detent plate  160  while being sufficiently rigidly supported. 
         [0035]    A proximal end  180  of park rod  120  includes a ninety degree bend provided with swaged elements to engage rotationally a mating aperture on detent plate  160 . Engagement/disengagement of the swaged end with detent plate  160  requires a rotation of control shaft  155  beyond the detent positions and therefore the swaged elements prevent accidental disengagement during operation. 
         [0036]    The coupling of proximal end  180  to detent plate  160  converts rotation of control shaft  155  to lateral translation of park rod  120 . A distal end of park rod  120  (not shown in  FIG. 1  because park rod  120  terminates within park sleeve  125 ) converts translation of park rod  120  into mechanical control of park pawl  115  as further described below. Pawl torsional spring  130 , coupled to pawl shaft  150 , rotationally biases park pawl  115  upwards and away from engagement with park lock gear  105 . The translation of park rod  120  overcomes this bias in appropriate situations to rotate park pawl  115  downwards toward engagement with park lock gear  105 . 
         [0037]    Park sleeve  125  includes a cylindrical perimeter and rotates about a transverse axis  185  relative to back half case  110 . This rotation of park sleeve  125  allows self-alignment in response to internal interactions of park rod  120  and park pawl  115 . A magnitude of rotation of park sleeve  125  is limited by a bracket  190  coupled to a complementary external cutout in park sleeve  125 . 
         [0038]    Pawl stopper  135  also includes a generally cylindrical perimeter and rotates about a transverse axis relative to back half case  110 . This rotation of pawl stopper  135  allows self-alignment in response to impacts of park pawl  115 . A magnitude of rotation of pawl stopper  135  is limited by bracket  190  coupled to a complementary external cutout in pawl stopper  135 . Bracket  190  thus concurrently retains both park sleeve  125  and pawl stopper  135  while permitting both structures to independently self-align to help meet space and weight budgets. 
         [0039]    A feature of the disclosed embodiment is that transverse axis  185 , the transverse axis of pawl stopper  135 , a rotational axis of pawl shaft  150 , and a rotational axis of control shaft  155  are all parallel. A manufacturing and assembly advantage of the disclosed embodiment of the present invention is that these elements engage and rotate within parallel bores disposed in back half case  110 . A milling machine would be able to create all these bores in a single pass without removing/repositioning back half case  110  in between creation of some of the bores. This means that all of the bores are all accurately positioned relative to each other. This improves assembly accuracy as the functional positions of these components are fixed without use of other parts. In contrast, if this assembly required machining in multiple planes, the resulting accuracy of those assembly would be less than an assembly able to be machined in a single plane. 
         [0040]    One critical component is positioning and operation of park sleeve  125 . Because park sleeve has a cylindrical perimeter it is easily installed into back half case  110  by inserting it into one of these accurately positioned bores. No other parts or brackets are needed to determine the operational position of park sleeve. The assembly is simplified in this fashion because no high accuracy position fixing bracket is required (such brackets can be complicated and possibly more expensive). A loose tolerance anti-rotation alignment bracket that limits rotation of park sleeve  125  replaces any position fixing bracket. 
         [0041]      FIG. 3  illustrates a sectional view of a portion of the park lock device of  FIG. 1  depicting an interaction of park rod  120  and park pawl  115  inside park sleeve  125  (not parked mode),  FIG. 4  illustrates a sectional view of a portion of the park lock device of  FIG. 2  depicting an interaction of park rod  120  and park pawl  115  inside park sleeve  125  (parked mode), and  FIG. 5  illustrates a sectional view of a portion of the park lock device detailing component orientation during transitions between the not parked mode of  FIG. 1  and the parked mode of  FIG. 2 . 
         [0042]    Park rod  120  includes a distal end  305  (e.g., a tip of park rod  120 ) opposite from proximal end  180  with a cam portion  310  disposed at distal end  305  and secured with an end stop. Cam portion  310  slidingly engages distal end  305  to move along park rod  120  between an extended position and a compressed position. A cam spring  315  disposed on distal end  305  between cam portion  310  and a stop  320  biases cam portion  310  towards the extended position. In the section view of  FIG. 3 , cam portion  310  includes two sloped portions: a steep forward portion  325  and a shallower rearward portion  330  (while appearing flat, in actuality these surfaces are radially symmetric). 
         [0043]    Park pawl  115  includes pawl portion  145  at a distal end away from pawl shaft  150 . Pawl portion  145  locks park lock gear  105  by engaging one uniform concave portion  140 . Park pawl  115  further includes a body portion  335  joining pawl shaft  150  to the distal end and a cam contact portion  340  also at the distal end opposing pawl portion  145 . Body portion  335  is laterally flat with pawl stopper  135  including a complementary flat chord  345  disposed on an intermediate portion of its cylindrical outer surface (that engages back half case  11 ), flat chord  345  rotating to align with body portion  335  when pawl stopper  135  is impacted by body portion  335 . Pawl stopper  135 , when self-aligning, rotates about its transverse axis so that flat chord  345  is substantially parallel to body portion  335 . Providing flat chord  345  over the entire width of body portion  335  distributes a contact load from each body portion  335  impact with pawl stopper  135  over a sufficiently large area that contact stresses are reduced to a desired level. 
         [0044]    In  FIG. 4 , park sleeve  125  includes an internal cam follower portion  405  that contacts cam portion  310  at a first contact point  410  along the slopes of cam portion  310 . First contact point  410  moves along cam portion  310  as cam portion  310  moves in and out of park sleeve  125 . (Note that there are some instances when park sleeve  125  does not contact cam portion  310  during operation of the park lock device.) Cam contact portion  340  contacts cam portion  310  at a second contact point  415  along the slopes of cam portion  310 . Second contact point  415  moves along cam portion  310  as cam portion  310  moves in and out of park sleeve  125  and park pawl  115  rotates. 
         [0045]    In the parked mode shown in  FIG. 4 , park sleeve  125  has self-aligned to produce a substantially zero resultant moment. The zero resultant moment is a consequence of the following particular arrangements. Park rod  120  is cylindrical at proximal end  180  and distal end  305 , distal end  305  including a longitudinal axis  420 . A line of action passes approximately through the transverse axis which is approximately passed through the center of park sleeve  125 . Longitudinal axis  420  is perpendicular to both a first imaginary line extending between transverse axis  185  and first contact point  410  as well as a second imaginary line extending between transverse axis  185  and second contact point  415 . This configuration provides that the resulting moment on park sleeve  125  is zero regardless of an angle that rearward portion  330  makes at first contact point  410 , a distance from transverse axis  185  to first contact point  410  or a magnitude of a force F at first contact point  410 . Further, park sleeve  125  self-aligns so that the distance from transverse axis  185  to first contact point  410  matches a distance from transverse axis  185  to second contact point  415 . Due to the resulting symmetric loading with respect to longitudinal axis  420  the resultant moment is also zero. Configuring park sleeve  125  and park rod  120  for relative self-alignment in park mode in this way provides two mechanisms to produce a zero resultant moment that reduces unnecessary stress on the park lock device. 
         [0046]    Both park sleeve  125  and pawl stopper  135  rotate for self-alignment, with bracket  190  used for both retaining them within back half case  110  at about the proper alignment and limiting the magnitudes of their rotations during self-alignments. Bracket  190  attaches to back half case  110  to “trap” park sleeve  125  and pawl stopper  135  while the external cuts on outside edges of park sleeve  125  and pawl stopper  135  engage bracket  190  to provide the rotation limitation. The park sleeve  125  rotation range allows for cam portion  310  to freely enter and exit during transitions of the park lock device between modes. Pawl stopper  135  rotation range allows for impacts by body portion  335  to rotate pawl stopper  135  so flat chord  345  is substantially parallel to body portion  335 . 
         [0047]    Two primary modes have been described above: parked mode and not parked mode. In normal operation, the park lock device transitions from the not parked mode shown in  FIG. 1  to the parked mode shown in  FIG. 2  and transitions from the parked mode to the not parked mode as determined by the controller. When transitioning from the parked mode to the not parked mode, the controller causes control shaft  155  to rotate clockwise (in  FIG. 1 ) which translates park rod  120  to the right and causes cam portion  310  to more fully enter into park sleeve  125 . In transition as park rod  120  continues to translate to the right, as shown in  FIG. 5 , forward portion  325  of cam portion  310  engages both cam follower portion  405  of park sleeve  125  and cam contact portion  340  of park pawl  115 . Further translation of park rod  120  to the right rotates park pawl  115  counterclockwise (downward in  FIG. 5 ) since forward portion  325  engages both park sleeve  125  and park pawl  115 . At the completion of the translation of park rod  120  to the right, park pawl  115 , park sleeve  125 , and cam portion  310  have the relationship shown in  FIG. 4  in which rearward portion  330  of cam portion  310  engages both park sleeve  125  and park pawl  115  in the parked mode. As long as the park lock device is configured as shown in  FIG. 4 , park pawl  115  cannot disengage from park lock gear  105  and forces exerted on cam portion  310  by park pawl  115  are not capable of translating park rod  120  to the left to enable disengagement. Only by translation of park rod  120  to the left, such as by rotation of control shaft  155  counterclockwise, will cam portion  310  transition to the intermediate mode shown in  FIG. 5  to enable park pawl  115  to rotate clockwise (upwards in  FIG. 4 ) and disengage from park lock gear  105 . 
         [0048]    When the EV is travelling faster than the park lock engagement speed and control shaft  155  moves to the park position, the park lock device is required to avoid entering into the park mode.  FIG. 6  illustrates a sectional view of a portion of the park lock device detailing an operational mode with the controller in the parked position prior to the parking pawl engaging the park gear. When the EV speed slows to the lock speed or slower, the park lock device automatically enters into the park mode in normal fashion as described herein. 
         [0049]      FIG. 7  illustrates a side view of park rod  120 ,  FIG. 8  illustrates a top view of park rod  120 , and  FIG. 9  illustrates a sectional view of a mid-portion of park rod  120  about A-A identified in  FIG. 7 . During a skid torque mode, park pawl  115  can impart significant bending/buckling loads to park rod  120 . Park rod  120  includes a mid-portion that has a cross-section which is generally oblong-shaped. The oblong having a major axis that is vertical. This oblong-shaped cross-section helps enable park rod  120  to better endure such skid torque mode. 
         [0050]      FIG. 10  illustrates a top view of the park lock device components from  FIG. 2  (park mode) isolated from the transmission case; and  FIG. 11  illustrates a side view of the park lock device components of  FIG. 10 . A pair of bolts  1005  is shown securing bracket  190  in place. Also illustrated is an enlarged head  1010  for pawl shaft  150 . Enlarged head  1010  interacts with a second half of the transmission case (not shown) that holds pawl shaft  150  in place while permitting it to freely turn. In this way no additional retention or mounting hardware is required, saving weight and decreasing component count. 
         [0051]      FIG. 12  illustrates an end view of park sleeve  125  detailing an opening  1205  receiving cam portion  310  of parking rod  120 ; and  FIG. 13  illustrates an isometric view of park sleeve  125  including receipt of cam portion  310  within opening  1205 . Parking rod  120  reciprocates in and out of opening  1205  with cam portion  310  engaging cam follower portion  405 . To help locate and guide parking rod  120  in this operation, opening  1205  is provided with an upper stopper  1210  and a pair of side-to-side guides  1215 . Upper stopper  1210  and side-to-side guides  1215  engage distal end  305  shown in  FIG. 3  as it reciprocates to maintain operational alignment within the plane of the transmission. Opening  1205  does not include a lower stopper and is open opposite of cam follower portion  405  because cam contact portion  340  of park pawl  115  is located at this position. In this way park sleeve  125  sandwiches park pawl  115  (i.e., cam contact portion  340 ) and surrounds cam portion  310  with the aid of park pawl  115 . Distal end  305  is guided and aligned without use of additional parts as is sometimes required in conventional systems. Also shown in  FIG. 13  is a cutout  1305  on an exterior portion of park sleeve  125 . Cutout  1305  cooperates with bracket  190  to provide rough rotational alignment of park sleeve  125  to properly orient opening  1205  and enable subsequent self-alignment. 
         [0052]    The system and methods above has been described in general terms as an aid to understanding details of preferred embodiments of the present invention. In the description herein, numerous specific details are provided, such as examples of components and/or methods, to provide a thorough understanding of embodiments of the present invention. While the park lock device has been described in the context of a narrow transmission of the type commonly found in electric vehicles, the disclosed solution is applicable to other transmission systems and methods. Some features and benefits of the present invention are realized in such modes and are not required in every case. One skilled in the relevant art will recognize, however, that an embodiment of the invention can be practiced without one or more of the specific details, or with other apparatus, systems, assemblies, methods, components, materials, parts, and/or the like. In other instances, well-known structures, materials, or operations are not specifically shown or described in detail to avoid obscuring aspects of embodiments of the present invention. 
         [0053]    Reference throughout this specification to “one embodiment”, “an embodiment”, or “a specific embodiment” means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the present invention and not necessarily in all embodiments. Thus, respective appearances of the phrases “in one embodiment”, “in an embodiment”, or “in a specific embodiment” in various places throughout this specification are not necessarily referring to the same embodiment. Furthermore, the particular features, structures, or characteristics of any specific embodiment of the present invention may be combined in any suitable manner with one or more other embodiments. It is to be understood that other variations and modifications of the embodiments of the present invention described and illustrated herein are possible in light of the teachings herein and are to be considered as part of the spirit and scope of the present invention. 
         [0054]    It will also be appreciated that one or more of the elements depicted in the drawings/figures can also be implemented in a more separated or integrated manner, or even removed or rendered as inoperable in certain cases, as is useful in accordance with a particular application. 
         [0055]    Additionally, any signal arrows in the drawings/Figures should be considered only as exemplary, and not limiting, unless otherwise specifically noted. Furthermore, the term “or” as used herein is generally intended to mean “and/or” unless otherwise indicated. Combinations of components or steps will also be considered as being noted, where terminology is foreseen as rendering the ability to separate or combine is unclear. 
         [0056]    As used in the description herein and throughout the claims that follow, “a”, “an”, and “the” includes plural references unless the context clearly dictates otherwise. Also, as used in the description herein and throughout the claims that follow, the meaning of “in” includes “in” and “on” unless the context clearly dictates otherwise. 
         [0057]    The foregoing description of illustrated embodiments of the present invention, including what is described in the Abstract, is not intended to be exhaustive or to limit the invention to the precise forms disclosed herein. While specific embodiments of, and examples for, the invention are described herein for illustrative purposes only, various equivalent modifications are possible within the spirit and scope of the present invention, as those skilled in the relevant art will recognize and appreciate. As indicated, these modifications may be made to the present invention in light of the foregoing description of illustrated embodiments of the present invention and are to be included within the spirit and scope of the present invention. 
         [0058]    Thus, while the present invention has been described herein with reference to particular embodiments thereof, a latitude of modification, various changes and substitutions are intended in the foregoing disclosures, and it will be appreciated that in some instances some features of embodiments of the invention will be employed without a corresponding use of other features without departing from the scope and spirit of the invention as set forth. Therefore, many modifications may be made to adapt a particular situation or material to the essential scope and spirit of the present invention. It is intended that the invention not be limited to the particular terms used in following claims and/or to the particular embodiment disclosed as the best mode contemplated for carrying out this invention, but that the invention will include any and all embodiments and equivalents falling within the scope of the appended claims. Thus, the scope of the invention is to be determined solely by the appended claims.