Patent Publication Number: US-8109522-B2

Title: Apparatus and method for coupling a disconnectable stabilizer bar

Description:
RELATED APPLICATIONS 
     This application is a continuation of U.S. Ser. No. 12/887,142 filed Sep. 21, 2010, which is a continuation of U.S. Ser. No. 11/926,658 filed Oct. 29, 2007 (now U.S. Pat. No. 7,832,739 issued Nov. 16, 2010), which claims the benefit of U.S. Provisional Patent Application No. 60/857,149 filed Nov. 6, 2006. The disclosures of these applications are incorporated by reference as if fully set forth in detail herein. 
    
    
     INTRODUCTION 
     The present invention generally relates to vehicle suspension systems and more particularly to an anti-roll suspension system having a pair of independently mounted stabilizer bar halves that can be selectively de-coupled from one another. 
     Traditional vehicle suspension systems include resilient devices, such as coil springs and leaf springs, to flexibly support a portion of a vehicle. These devices enable all of the vehicle wheels to maintain contract with the ground when traversing uneven terrain. Segregating the vehicle into unsprung and sprung portions in this manner is also useful for preventing severe impulsive forces from being transmitted to the vehicle occupants. 
     It is known that when vehicle travels around a corner, centrifugal forces acting on the vehicle tend to cause the sprung portion of the vehicle to roll. In severe instances, the effects of roll can cause instability and impede the ability of the driver to control the vehicle. Although the effects of roll are more pronounced with vehicles having a comparatively high center of gravity, such as vans or trucks, every vehicle is affected by roll. 
     In tuning the ride and handling of a vehicle, it is often desirable to soften or lower the spring rate of the suspension&#39;s springs to provide a softer, less harsh ride. One of the main drawbacks associated with this approach is that a suspension system having springs with a relatively low spring rate permits the vehicle body to roll at a relatively higher rate. Accordingly, it would seem that the combination of springs with a very low spring rate and a relatively stiff stabilizer bar would optimize both the ride and handling of the vehicle. 
     The relatively stiff stabilizer bar, however, tends to directly connect the vehicle wheels such that the motion of one wheel is copied to another wheel. If a vehicle so equipped was to strike a bump with one wheel, for example, the upward force (i.e., jounce) imparted to that wheel would be transmitted through the stabilizer bar to the opposite wheel, causing the opposite wheel to move in an upward direction. This “cross-talk” between the vehicle wheels can be undesirable. 
     Another drawback of stabilizer bars is that their torsional stiffness inhibits the free travel of the vehicle wheels. Modern materials and design techniques have substantially reduced the weight of the vehicle wheels and mounting structures to such an extent that the weight of a wheel and its mounting structure is typically insufficient to cause the stabilizer bar to rotate. While this problem is rarely, if ever, noticed on the relatively flat surfaces of modern roads, it can become apparent when the vehicle is operated over un-even terrain. In some situations, it is possible for one of the vehicle wheels to remain in an elevated position over a dip in the terrain due to the torsional resistance of the stabilizer bar. While situations of this severity are not routinely encountered, the fact remains that the stabilizer bar can reduce vehicle traction in some situations. 
     Various solutions that address the aforementioned drawbacks are disclosed in U.S. Pat. No. 6,428,019 entitled “Semi-Active Anti-Roll System” and U.S. Pat. No. 6,637,757 entitled “Apparatus And Method For Coupling A Disconnectable Stabilizer Bar System”, the disclosures of which are hereby incorporated by reference as if fully set forth in detail herein. Stabilizer bar products incorporating one or more innovations disclosed in the &#39;019 and/or the &#39;757 patents are commercially manufactured and marketed by American Axle &amp; Manufacturing under the SmartBar™ product line. While such configurations are suitable for their intended purpose, they are nonetheless susceptible to improvement. 
     SUMMARY 
     In one form, the present teachings provide a stabilizer bar system that includes a clutch and first and second arms. The clutch has a housing assembly, a plurality of coupling members and an actuator. The housing assembly defines a bore with a longitudinal axis. The coupling members are arranged concentrically about the longitudinal axis. The actuator includes a plunger that is slidably disposed along the longitudinal axis between a retracted position and an extended position. The actuator is selectively operable for moving the plunger to the extended position to apply a force that moves at least one of the coupling members along the longitudinal axis from a first position to a second position. The first arm is coupled to a second one of the coupling members and the second arm is non-rotatably coupled to the housing assembly. Placement of the first one of the coupling members in the first position non-rotatably couples the first one of the coupling members to the second one of the coupling members to inhibit relative rotation between the first and second arms. The first one of the coupling members is disengaged from the second one of the coupling members to permit relative rotation between the first and second arms when the first one of the coupling members is positioned in the second position. 
     In another form, the present teachings provide a method that includes: providing a stabilizer bar system having a first arm member, a second arm member and a clutch assembly, the clutch assembly including a plurality of concentrically disposed coupling members and an actuator; and activating the actuator to cause the actuator to apply a force to a first one of the coupling members, the force being applied concentrically about the first one of the coupling members, the first one of the coupling members responsively translating and disengaging a second one of the coupling members to permit the first arm member to rotate relative to the second arm member. 
     In yet another form, the present teachings provide a stabilizer bar system that includes a clutch and first and second generally L-shaped stabilizer bar portions. The clutch has a housing assembly, a first transmission member, a second transmission member, and an actuator. The housing assembly defines a bore having a longitudinal axis. The first and second transmission members are received in the bore. The second transmission member is non-rotatably coupled to the housing assembly and slidable within the bore between a first position and a second position. The second transmission member is non-rotatably coupled to the first transmission member when the second transmission member is in the first position. The first transmission member is rotatable relative to the second transmission member when the second transmission member is in the second position. The actuator includes a coil and a plunger that is movable along the longitudinal axis between a returned position and an extended position. The plunger is coupled to the second transmission member. The first generally L-shaped stabilizer bar portion is non-rotatably coupled to the first transmission member and the second generally L-shaped stabilizer bar portion is non-rotatably coupled to the housing assembly. Actuation of the actuator moves the plunger into the extended position to cause a force to be applied concentrically to the second transmission member that pushes the second transmission member toward the second position. 
     In still another form, the present teachings provide a stabilizer bar system that includes first and second stabilizer bar members and a clutch with a housing, a first coupling member, a second coupling member and an actuator. The housing defines a bore into which the first stabilizer bar member is received. The second stabilizer bar member is non-rotatably coupled to the housing. The first coupling member is received in the bore and is rotatable about an axis. The first coupling member is non-rotatably coupled to the first stabilizer bar member. The second coupling member is an annular structure that is axially movable along the rotational axis of the first coupling member between a first position, in which the second coupling member non-rotatably couples the first coupling member to the housing, and a second position that permits rotation of the first coupling member relative to the housing. The actuator is configured to move the second coupling member between the first and second positions. The actuator includes a plunger that is axially movable along the rotational axis. The second coupling member is disposed concentrically about the plunger and the plunger extending at least partially through the second coupling member. 
     In yet another form, the present teachings provide a stabilizer bar system that includes first and second stabilizer bar members and a clutch with a housing, a first coupling member, a second coupling member, and an actuator. The housing defines a bore into which the first stabilizer bar member is received. The second stabilizer bar member is non-rotatably coupled to the housing. The first coupling member is received in the bore and is rotatable about an axis. The first coupling member is non-rotatably coupled to the first stabilizer bar member. The second coupling member is an annular structure that is axially movable along the rotational axis of the first coupling member between a first position, in which the second coupling member non-rotatably couples the first coupling member to the housing, and a second position that permits rotation of the first coupling member relative to the housing. The actuator is configured to move the second coupling member between the first and second positions and includes a plunger, an annular coil, a first spring and a second spring. The plunger is axially movable along the rotational axis. The coil is disposed concentrically about the plunger. The first spring biases the second coupling member toward the first position. The second spring permits relative axial movement of the plunger relative to the second coupling member such that the plunger can be moved by a magnetic field created by the coil when the first and second coupling members are torque-locked. 
     In yet another form, the present teachings provide a stabilizer bar system that includes a first stabilizer bar, a second stabilizer bar and a clutch having a clutch housing and a plurality of coupling members housed in the clutch housing. The first stabilizer bar is received in the clutch housing for rotation relative to the clutch housing about a rotational axis. The second stabilizer bar is fixedly coupled to the clutch housing. The coupling members are configured to selectively non-rotatably couple the first stabilizer bar to the clutch housing such that the clutch housing is employed to transmit torque between the first and second stabilizer bars. 
     In still another form, the present teachings provide a stabilizer bar system that includes a first stabilizer bar, a clutch housing that is fixedly coupled to the first stabilizer bar, a second stabilizer bar that is rotatable relative to the clutch housing about a rotational axis, and a means for selectively non-rotatably coupling the second stabilizer bar to the clutch housing. The selective coupling means includes a plunger that is axially movable along the rotational axis. 
     Further areas of applicability will become apparent from the description provided herein. It should be understood that the description and specific examples are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The drawings described herein are for illustration purposes only and are not intended to limit the scope of the present disclosure in any way. 
         FIG. 1  is a perspective view of a portion of a vehicle having an independent suspension with an anti-roll system constructed in accordance with the teachings of the present disclosure; 
         FIG. 2  is an exploded perspective view of the anti-roll system of  FIG. 1 ; 
         FIG. 3  is a section view taken longitudinally through a portion of the anti-roll system of  FIG. 1  illustrating the second transmission member in the engaged condition; 
         FIG. 4  is a section view similar to that of  FIG. 3  but illustrating the second transmission member in the disengaged condition; 
         FIG. 5  is a longitudinal section view similar to that of  FIG. 3  but illustrating another anti-roll system constructed in accordance with the teachings of the present disclosure; 
         FIG. 6  is a perspective view of a portion of the anti-roll system of  FIG. 5  in partial section illustrating the second transmission member and the controller assembly in greater detail; 
         FIG. 7  is a plot of the electrical voltage and electrical current applied to the coil assembly of the anti-roll system of  FIG. 5  and the displacement of the plunger of the anti-roll system of  FIG. 5  as a function of time; and 
         FIG. 8  is a longitudinal section view of a portion of an anti-roll system similar to that of  FIG. 5  but illustrating a controller that is encapsulated in an end cap of the clutch assembly. 
     
    
    
     DETAILED DESCRIPTION OF THE VARIOUS EMBODIMENTS 
     With reference to  FIG. 1  of the drawings, an exemplary vehicle is shown and can include an independent front suspension system  10 . The independent front wheel suspension can be of a type having suspension components at each wheel that are suspended from the vehicle frame structure  12 . In the particular example provided, the frame structure  12  can include a pair of longitudinal side rails  14  and a crossbeam  16 , but those of ordinary skill in the art will appreciate that the term “frame structure” need not refer to a frame as such, but could also refer to one or more regions of the vehicle body that act as an integrated frame structure. Those of ordinary skill in the art will appreciate that although a front suspension system is illustrated and described herein, the teachings of the present disclosure are also applicable to a rear suspension system. 
     At each wheel, the suspension system  10  can include a lower control arm  18  and an upper control arm  20 . The lower and upper control arms  18  and  20  can be pivotally attached to the frame structure  12 . A strut assembly, which can have a helical coil spring  22  and a strut damper  24 , can be retained between an intermediate portion of the lower control arm  18  and the frame structure  12  to support the weight of the vehicle body (not shown) and any loads that are transmitted through the lower control arm  18 . The upper control arm  20  can be connected to the lower control arm  18  by a steering knuckle  26 . A hub and rotor assembly  28  can be rotatably attached to a spindle portion (not specifically shown) of the steering knuckle  26  such that a wheel and tire (not shown) may be mounted thereon. The suspension system  10  can further include an anti-roll system  50  that can include a stabilizer bar assembly  52  and a pair of end links  54  that can connect the ends  56  of the stabilizer bar assembly  52  to the lower control arms  18 . The stabilizer bar assembly  52  can include first and second stabilizer bar members  60   a  and  60   b , respectively, a clutch assembly  62  and a controller assembly  64 . 
     With additional reference to  FIG. 2 , the first stabilizer bar member  60   a  can be generally L-shaped, having an arm portion  70 , which can have a mounting portion  72 , and a leg portion  74  that can be coupled to an end of the arm portion  70  opposite the mounting portion  72 . The mounting portion  72  can be configured to be coupled to the frame structure  12  in a conventional manner, such as the end link  54 . The leg portion  74  can be rotatably coupled to the frame structure  12  in a conventional manner (such as a bracket  76 ) and can include a coupling portion  78  that can couple the first stabilizer bar member  60   a  to the clutch assembly  62 . In the example provided, the coupling portion  78  includes a journal  80 , a coupling member  82  and a snap-ring groove  84  that is disposed on a side of the coupling member  82  opposite the journal  80 . The coupling member  82  can have a non-circular shape and in the example provided, includes a plurality of longitudinally-extending teeth or splines  86 . 
     The second stabilizer bar member  60   b  can also be generally L-shaped and have an arm portion  90  and a leg portion  94 . The arm portion  90  can be similar to the arm portion  70  of the first stabilizer bar member  60   a . The leg portion  94  can be coupled to an end of the arm portion  90  and can include a coupling member  102  that can be employed to non-rotatably couple the second stabilizer bar member  60   b  to the clutch assembly  62 . In the particular example provided, the coupling member  102  includes a flange  104  that can be fixedly coupled to the clutch assembly  62 , as will be discussed in detail below, but those of ordinary skill in the art will appreciate that the coupling member  102  could be formed in any desired manner that permits the second stabilizer bar member  60   b  to be non-rotatably coupled to the clutch assembly  62 . 
     With reference to  FIGS. 2 and 3 , the clutch assembly  62  can include a housing assembly  120 , a first transmission member  122 , a second transmission member  124 , a coil assembly  126 , a plunger  128 , a sleeve  130 , a first spring  132 , a second spring  134  and a retaining ring  136 . The housing assembly  120  can include a first end cap  140 , a second end cap  142  and a housing  144 . The first end cap  140  can include a cap member  150 , a pair of bearings  152  and a seal  154 . The cap member  150  can be formed of any appropriate material and can include a body  160  and a flange  162 . The body  160  can define a central bore  164 , which can be oriented along a longitudinal axis of the cap member  150 , a sensor boss  166 , a pilot portion  168  and an end face  170 . The sensor boss  166  can have a flat outer surface  172  and can define a sensor aperture  174  that can extend through a side of the body  160 . The sensor aperture  174  can be disposed generally perpendicular to both the flat outer surface  172  and the central bore  164 . The pilot portion  168  can be an annular structure that can be generally concentric with the central bore  164 . The pilot portion  168  can cooperate with another portion of the cap member  150 , such as the flange  162 , to define a shoulder  180 . The end face  170  can be an axial end face of a portion of the cap member  150 , such as the pilot portion  168 , and can be spaced axially apart from the shoulder  180 . The flange  162  can be disposed about the body  160  and can include a plurality of bosses  182 . 
     The second end cap  142  can include a cap member  190  and a plunger backstop  192 . In the particular example provided, the cap member  190  and the plunger backstop  192  are unitarily formed of an appropriate material, such as a magnetic ferrous-alloyed powdered metal, but it will be appreciated that they could be formed as discrete components that are coupled to one another to facilitate the manufacture of the second end cap  142  and/or the use of different materials for the cap member  190  and the plunger backstop  192 . The cap member  190  can include a body  194  and a flange  196 . The body  194  can define a coupling portion  200 , a pilot portion  202  and an end face  204 . The coupling portion  200  can be configured to engage the coupling member  102  of the second stabilizer bar member  60   b  such that the second stabilizer bar member  60   b  and the cap member  190  are non-rotatably coupled to one another. The pilot portion  202  can be a generally cylindrical structure and can cooperate with another portion of the cap member  190 , such as the flange  196 , to define a shoulder  206 . The end face  204  can be an axial end face of a portion of the cap member  190 , such as the pilot portion  202 , and can be spaced axially apart from the shoulder  206 . The flange  196  can be disposed about the body  194  and can include a plurality of bosses  208 . The plunger backstop  192  can be a generally cylindrical structure that can be generally concentric with the pilot portion  202  and can project from the end face  204 . The distal end  210  of the plunger backstop  192  can include a plunger aperture  212  that can be disposed about a longitudinal axis of the plunger backstop  192 . In the particular example provided, the plunger aperture  212  has a frusto-conical shape having a cone angle  214  of about 60° to about 120° and a flat end wall  216 . 
     The housing  144  can include a body  220  and first and second end flanges  222  and  224 , respectively. The body  220  can be a hollow generally cylindrical structure and can include a plurality of mounting pads  226 , a bore  228 , a first coupling member  230  and an interior wall  232 . The mounting pads  226  can be formed on an exterior surface of the body  220  and can each include one or more threaded apertures  240 . The bore  228  can be disposed longitudinally through the body  220  and can define a pilot bore  240 , a first portion  242 , a second portion  244  and a third portion  246  that can be concentric with one another. The pilot bore  240  can be sized and configured to receive the pilot portion  168  of the cap member  150  to align the central bore  164  concentrically with the bore  228 . The first portion  242  can be sized to receive the second spring  134 , the second portion  244  can be sized to receive the sleeve  130  and the third portion  246  can be sized to receive the coil assembly  126  and the pilot portion  202  of the cap member  190 . The first coupling member  230  can include a plurality of circumferentially spaced-apart teeth or splines  250  that can be located axially between the pilot bore  240  and the first portion  242 . The interior wall  232  can be disposed between the second and third portions  244  and  246  of the bore  228 . An aperture  252  can be formed through the interior wall  232 . 
     The first and second end flanges  222  and  224  can be disposed about the body  220  and can each including a plurality of bosses  260 . The bosses  182  and  208  of the flanges  162  and  196 , respectively, can be aligned to the bosses  260  of the first and second end flanges  222  and  224 , respectively, and threaded fasteners  262 , such as cap screws, can be employed to fixedly but removably couple the first and second end caps  140  and  142  to the housing  144  such that the body  220  abuts the shoulders  180  and  206  of the cap members  150  and  190 , respectively. In the example provided, a sleeve dowel  270  is fitted to a counter bore  272  that is formed in one of the bosses  260  in each of the first and second end flanges  222  and  224  as well as and an associated counter bore or through hole that is formed in the bosses  182  and  208  in the flanges  162  and  196 . The sleeve dowels  270  can radially locate the first and second end caps  140  and  142  to the housing  144  such that the flat outer surface  172  of the sensor boss  166  is aligned in a predetermined manner to the mounting pads  226 . In the particular example provided, the threaded fasteners  262  are also employed to fixedly but removably secure the flange  104  of the second stabilizer bar member  60   b  to the second end cap  142 . 
     The first transmission member  122  can be a hollow sleeve having an internal bore  300 , a second coupling member  302  and a third coupling member  304 . The first transmission member  122  can be rotatable but axially fixed to the first end cap  140 . In the example provided, the first transmission member  122  is supported by the bearings  152  in the first end cap  140 . The second coupling member  302  can engage the coupling member  82  of the first stabilizer bar member  60   a  to inhibit relative rotation therebetween. In the particular example provided, the second coupling member  302  can include a plurality of circumferentially spaced-apart longitudinally-extending teeth or splines  306 , which are formed about the interior diameter of the internal bore  300 , that can matingly engage the splines  86  of the coupling member  82  of the first stabilizer bar member  60   a . The third coupling member  304  can have a non-circular shape and in the example provided, includes a plurality of longitudinally-extending teeth or splines  310 . One of the splines  310  (e.g., spline  310   a ) can be sized differently than the remaining splines  310 . The first stabilizer bar member  60   a  can be coupled to first transmission member  122  to inhibit relative axial movement therebetween. In the example provided, a snap ring  314  is received in the snap ring groove  84  and engages another groove  316  that is formed on the first transmission member  122 . 
     The second transmission member  124  can include a body  320 , a fourth coupling member  322  and a fifth coupling member  324 . The body  320  can include a bore  326  and one or more sensor targets  328 . The bore  326  can include a pilot portion  330 . The fourth coupling member  322  can be configured to selectively engage the third coupling member  304  of the first transmission member  122  to inhibit relative rotation therebetween. In the particular example provided, the fourth coupling member  322  can include a plurality of circumferentially spaced-apart longitudinally-extending teeth or splines  340 , which are formed about the interior diameter of the bore  326 , that can matingly engage the splines  310  of the third coupling member  304 . While not specifically shown, it will be appreciated that the spacing between two of the splines  340  can be configured to receive the spline  310   a  to thereby key the third coupling member  304  to the fourth coupling member  322  (i.e., the splines  310  can mesh with the splines  340  in only one rotational position). The fifth coupling member  324  can have a non-circular shape and in the example provided, includes a plurality of longitudinally-extending teeth or splines  344 . In the example provided, the sensor target  328  is an annular rim or projection that is disposed about the body  320  and which has first and second wall members  350  and  352 , respectively, that are generally perpendicular to the bore  326 . 
     The second transmission member  124  can be disposed about the first transmission member  122  and can be received in the bores  164  and  228  such that the sensor target  328  is disposed in-line with the sensor aperture  174 . The second transmission member  124  can be axially movable relative to the first transmission member  122  between a first or engaged position in which the fourth coupling member  322  is non-rotatably coupled to the third coupling member  304  as shown in  FIG. 3 , and a second or disengaged position in which the fourth coupling member  322  is decoupled from the third coupling member  304  to permit relative rotation between the first and second transmission members  122  and  124  as shown in  FIG. 4 . Those of ordinary skill in the art will appreciate that positioning of the second transmission member  124  in the first position can non-rotatably couple the first stabilizer bar member  60   a  to the housing  144  (and thereby to the second stabilizer bar member  60   b ), while positioning of the second transmission member  124  in the second position can decouple the first stabilizer bar member  60   a  from the housing  144  to thereby permit relative rotation between the first and second stabilizer bar members  60   a  and  60   b.    
     The coil assembly  126  can be disposed in the third portion  246  of the bore  228  in the housing  144  and can include an annular bobbin  400  and a coil of wire  402  that is wound around about the bobbin  400 . The coil of wire  402  can include a pair of terminals  406  that are electrically coupled to the controller assembly  64 . A first side of the coil assembly  126  can abut the interior wall  232  in the housing  144  and a second, opposite side of the coil assembly  126  can abut the end face  204  of the cap member  190 . The portion of the coil assembly  126  adjacent the second end can be disposed about the plunger backstop  192 . 
     The plunger  128  can be a generally cylindrical shaft-like structure having a body portion  450  and a flange portion  452 . The body portion  450  can have a tip  460  and a ring groove  462 . The tip  460  can be configured in a manner that is complementary to the configuration of the plunger aperture  212  in the plunger backstop  192 . In the example provided, the tip can has a frusto-conical shape with a cone angle  464  of about 60° to about 120°. It will be appreciated that the cone angle  464  and the cone angle  214  can be about equal. The ring groove  462  can be formed about the body portion  450  and can be sized to receive the retaining ring  136 . A through-hole  466  can be formed through the body portion  450  and can be shaped and sized in any appropriate manner. For example, the size and shape of the through-hole  466  can be selected to reduce or eliminate the build-up of pressure that might otherwise occur when the plunger  128  is translated and/or to reduce the overall mass of the plunger  128 . The body portion  450  can be received into the bore  228  of the housing  144  and can extend through the aperture  252  in the interior wall  232 . The flange portion  452  can be coupled to an end of the body portion  450  opposite the tip  460 . 
     The sleeve  130  can be an annular structure having a body  500  and a flange member  502 . The body  500  can be fixedly coupled (e.g., press fit, welded) to the second transmission member  124  and can define an aperture  504  into which the end of the plunger  128  opposite the tip  460  is disposed. Although the sleeve  130  and the second transmission member  124  are illustrated and described herein as being discrete components, it will be appreciated that these components could be unitarily formed. The flange member  502  can be coupled to an end of the body  500  opposite the second transmission member  124 . The first spring  132  can be configured to bias the plunger  128  in a direction opposite the plunger backstop  192 . In the example provided, the first spring  132  is a compression spring that is fitted about the body portion  450  of the plunger  128  between the flange portion  452  and the flange member  502  of the sleeve  130 . Those of ordinary skill in the art will appreciate from this disclosure that the first spring  132  and the sleeve  130  can cooperate to couple the plunger  128  to the second transmission member  124 . 
     The second spring  134  can be configured to bias the second transmission member  124  toward the engaged position ( FIG. 3 ). In the particular example provided, the second spring  134  is a compression spring that is fitted about the sleeve  130  between a shoulder  520  in the housing  144  and an axial end face of the second transmission member  124 . 
     The retaining ring  136  can be disposed in the retaining ring groove  462  in the body portion  450  of the plunger  128  to limit the distance by which the flange member  502  of the sleeve  130  can be spaced apart from the flange portion  452  of the plunger  128 . 
     The controller assembly  64  can include a controller  600  and a controller housing  602 . The controller  600  can include hardware for controlling the operation of the clutch assembly  62  and a sensor suite  606  having one or more sensors that sense various parameters or conditions of the clutch assembly  62 , the vehicle V ( FIG. 1 ) and/or the environment. In the example provided, the sensor suite  606  includes a single back-biased Hall-effect sensor that is configured to sense the sensor target  328 , such as an AT635LSETN-T sensor marketed by Allegro MicroSystems of Worcester Mass., but those of ordinary skill in the art will appreciate that the number and type of sensors that are employed may be selected in accordance with a desired level (i.e., quantity and quality) of information relating to the operation of the anti-roll system  50 . For example, additional sensors may be employed to identify a direction of travel of the second transmission member  124  or whether the plunger  128  and/or the second transmission member  124  has moved sufficiently to permit the controller assembly  64  to reduce the power that is transmitted to the coil assembly  126 . In this regard, it will be appreciated that the controller assembly  64  can operate the coil assembly  126  in a first mode to initiate movement of the second transmission member  124 , and a second mode to maintain the second transmission member  124  in a desired position. For example, the controller assembly  64  can provide DC electrical power of a predetermined voltage to the coil assembly  126  to operate it in the first mode, and can provide DC electrical power in a pulse-width-modulated (PWM) form to the coil assembly  126  to operate it in the second mode. The supply of electrical power to the coil assembly  126  in a PWM form is desirable as it reduces overall energy consumption and generates relatively lower amounts of heat as compared to straight DC electrical power. It will be appreciated that electrical power may be transmitted to the coil assembly  126  in a PWM form during the first mode and that the duty cycle employed for the first and second modes can be different. 
     The controller housing  602  can be a metallic or plastic enclosure that is configured to sealingly enclose the controller  600  therein. In the particular example provided, the controller housing  602  is a box-like structure having a plurality of mounting bosses  610  that are employed to fixedly but removably couple the controller housing  602  to the mounting pads  226  of the housing  144  via threaded fasteners (not shown). The sensor suite  606  can extend from a lower wall  612  of the controller housing  602  and can be received into the sensor aperture  174  in the sensor boss  166 . One or more resilient seal members  603  can be employed to form a seal between the controller  600  and the housing assembly  120  to thereby inhibit the ingress of dirt, debris and moisture into the controller  600  and/or the housing assembly  120 . A connector  616 , which can be coupled to the controller  600 , can extend through an upper wall  618  of the controller housing  602 . The connector  616  can facilitate the electrical coupling of the controller  600  to a power source (not shown) and to a vehicle controller/car area network (CAN) (not shown) to permit electrical power and appropriate data to be transmitted to the controller  600  and/or from the controller  600  to the CAN. The controller  600  can be electrically coupled to the terminals  406  of the coil of wire  402 . 
     In operation, the second spring  134  biases the second transmission member  124  toward the first position so that the third and fourth coupling members  304  and  322  are engaged to one another to thereby couple the first and second stabilizer bar members  60   a  and  60   b  with one another. As those of ordinary skill in the art will appreciate, movement of the first and second stabilizer bar members  60   a  and  60   b  relative to one another will transmit torque through the clutch assembly  62 . Torque can be transmitted concentrically through the clutch assembly  62  (i.e., evenly about the axis along which the second transmission member  124  slides, which in the example provided is the longitudinal axis of the bore  228  in the housing  144 ) so that the various translating components, such as the second transmission member  124 , are not subjected to side-loads. 
     When de-coupling of the first and second stabilizer bar members  60   a  and  60   b  is desired, the controller assembly  64  can energize the coil assembly  126  to cause the plunger  128  to move toward the plunger backstop  192  and compress the first spring  132 . In situations where relatively little or no torque is being transmitted through the clutch assembly  62 , the force exerted by the (compressed) first spring  132  onto the sleeve  130  can cause the sleeve  130  to translate in a direction toward the interior wall  232  of the housing  144 . As the sleeve  130  and the second transmission member  124  are coupled to one another, translation of the sleeve  130  will effect a corresponding translation of the second transmission member  124  that positions the second transmission member  124  into the second position wherein the third and fourth coupling members  304  and  322  are decoupled from one another to thereby decouple the first and second stabilizer bar members  60   a  and  60   b  from one another. It will be appreciated from this disclosure that the positioning of the second transmission member  124  in the second or disengaged position ( FIG. 4 ) can compress the second spring  134  between the second transmission member  124  and the housing  144 . It will be appreciated that the clutch assembly  62  ( FIG. 2 ) can be configured so as to couple the first and second stabilizer bar members  60   a  and  60   b  with one another in the event that the clutch assembly  62  ( FIG. 2 ) experiences a loss of electrical power. 
     Those of ordinary skill in the art will appreciate from this disclosure that the fourth coupling member  322  may resist sliding relative to the third coupling member  304  in situations where a relatively high level of torque is being transmitted through the clutch assembly  62  (this phenomenon is herein after referred to as “torque lock”). Accordingly, when the plunger  128  is shifted toward the plunger backstop  192  in such situations, the first spring  132  will be compressed between the flange portion  452  of the plunger  128  and the flange member  452  of the sleeve  130 . When the torque that is transmitted through the clutch assembly  62  reduces sufficiently, the force exerted by the (compressed) first spring  132  will urge the sleeve  130  toward the interior wall  232  to thereby move the second transmission member  124  into the second or disengaged position ( FIG. 4 ). 
     The sensor suite  606  can be employed to monitor a position of the sensor target  328  and can generate a signal to indicate that the sensor target  328  has moved by a distance that correlates to the disengagement of the third and fourth coupling members  304  and  322 . It will be appreciated that electrical energy may be provided by the controller  600  using a pulse-width-modulation technique. The controller  600  can employ a first, relative high energy duty cycle so that the apparent voltage provided to the coil assembly  126  is relatively high to initiate movement of the plunger  128  to uncouple the first and second stabilizer bar members  60   a  and  60   b  from one another. In response to a signal from the sensor suite  606  that indicates that the second transmission member  124  has moved sufficiently to de-couple the third and fourth coupling members  304  and  322 , the controller  600  can employ a second, relatively lower energy duty cycle to maintain the second transmission member  124  in the second or disengaged position. In this regard, a relatively lower duty cycle can be employed to hold or maintain the plunger  128  in the second position. The lower energy duty cycle can provide a relatively lower apparent voltage and can reduce energy consumption and the generation of heat by the coil assembly  126 . 
     To re-engage the first and second stabilizer bar members  60   a  and  60   b  to one another (e.g., the spline  310   a  is not aligned to an associated space between a pair of the splines  340 ), the controller assembly  64  can terminate the supply of electrical power to the coil assembly  126 , which can permit the second spring  134  to urge the second transmission member  124  into the first position so that the third and fourth coupling members  304  and  322  are coupled to one another. In situations where the third and fourth coupling members  304  and  322  are not aligned to one another, the force exerted by the compressed second spring  134  will cause the second transmission member  124  to translate when the third and fourth coupling members  304  and  322  are aligned to one another. 
     While the anti-roll system  50  has been described thus far as including a controller assembly  64  that is mounted to an exterior surface of a clutch assembly  62 , those of ordinary skill in the art will appreciate that the invention, in its broader aspects, may be constructed somewhat differently. For example, the controller assembly can be housed in the second end cap as shown in  FIGS. 5 and 6 . In this arrangement, the anti-roll system  50 ′ can include a clutch assembly  62 ′ and a controller assembly  64 ′. Except as otherwise described below, the clutch assembly  62 ′ and the controller assembly  64 ′ can be generally similar or identical to the clutch assembly  62  and controller assembly  64  of  FIG. 1 . 
     The clutch assembly  62 ′ can include a housing assembly  120 ′ and a second transmission member  124 ′. The housing assembly  120 ′ can include a first end cap  140 ′, a second end cap  142 ′ and a housing  144 ′. The first end cap  140 ′ and the housing  144  can be generally similar to the first end cap  142  and the housing  144  of  FIG. 2  except that the first end cap  140 ′ need not include a sensor aperture  150  ( FIG. 2 ) and the housing  144 ′ need not include the mounting pads  226  ( FIG. 2 ). The second end cap  142 ′ can include a cap member  190 ′ and a plunger backstop  192 ′. The cap member  190 ′ can include a body  194 ′ and a flange  196 ′. The body  194 ′ can define a coupling portion  200 ′ and a pilot portion  202 ′. 
     The coupling portion  200 ′ can be configured to engage the coupling member  102 ′ of the second stabilizer bar member  60   b ′ such that the second stabilizer bar member  60   b ′ and the cap member  190 ′ are non-rotatably coupled to one another. In the particular example provided, the coupling portion  200 ′ includes an internal tapered bore  1000  and a threaded coupling segment  1002 , while the second stabilizer bar member  60   b ′ includes a tapered stem  1006  and a circumferentially-extending locking groove  1008 . A fastener  1010  and a pair of keepers or shell members  1012  can be employed to fixedly couple the tapered stem  1006  to the coupling portion  200 ′. The shell members  1012  can have a circumferentially extending rib  1014  that can be received into the locking groove  1008 . The fastener  1010  can have a threaded portion  1018 , which can threadably engage the threaded coupling segment  1002 , and a shoulder  1020  that can abut the shell members  1012 . Accordingly, the fastener  1010  can be tightened to the threaded coupling segment  1002  such that the shoulder  1020  of the fastener  1010  will drive the shell members  1012  (and thereby the tapered stem  1006 ) toward the housing  144 ′ and thereby engage the surface of the tapered stem  1006  to the surface of the internal tapered bore  1000 . It will be appreciated that the tapers of the stem  1006  and the bore  1000  can conform to be a standard taper configuration, such as a #2 or #3 Morse taper, and that mating engagement of these surface can transmit torque. It will be further appreciated that the first stabilizer bar member  60   a ′ and the first transmission member  122 ′ can be configured in a similar manner. In the particular example provided, the seal  154 ′ that is carried by the first end cap  140 ′ sealingly engages the fastener  1010 ′ to inhibit the ingress of debris and moisture to the interior of the first end cap  140 . It will be appreciated that the seal  154 ′ could seal against the first stabilizer bar member  60   a ′ or the first transmission member  122 ′ in the alternative. 
     The pilot portion  202 ′ can be a generally cylindrical structure and can receive the controller assembly  64 ′ and the housing  144 ′ therein. A seal member  1030  can be disposed between the outer diameter of the housing  144 ′ and the inner diameter of the pilot portion  202 ′. 
     The flange  196 ′ can include an end face  204 ′ and a threaded coupling portion  1034 . The end face  204 ′ can be abutted against a circumferentially extending flange  1036  that is formed on the housing  144 ′. A fastener  1038  can be disposed over the housing  144 ′ and can threadably engage the threaded coupling portion  1034  to permit the flange  196 ′ to be drawn toward the housing  144 ′ such that the end face  204 ′ abuts the circumferentially extending flange  1036 . It will be appreciated that the opposite end of the housing  144 ′ and first end cap  140 ′ can be constructed in a similar manner. In the particular example provided, the fastener  1038 ′ is disposed over the first end cap  140 ′ and threadably engaged to threads  1040  that are formed on the housing  144 ′. 
     The controller assembly  64 ′ can be a module that can be received into the pilot portion  202 ′ of the second end cap  142 ′. The controller assembly  64 ′ can be fixedly coupled and sealingly engaged to the second end cap  142 ′. The controller assembly  64 ′ can include a circuit board  1050  having and one or more connector ports  1052 . The circuit board  1050  can include a sensor aperture  1056  and a sensor suite  606 ′ having one or more sensors  1058 , such as a Hall-effect sensor or an optical sensor, such as an LED emitter/detector). The connector ports  1052  can be coupled to the circuit board  1050  and can extend through the second end cap  142 ′. The connector ports  1052  facilitate the coupling of one or more wire harnesses (not shown) to the controller assembly  64 ′ to facilitate the transmission of electrical power to the anti-roll system  50 ′ as well as to facilitate the transmission of data to and from the controller assembly  64 ′. 
     The second transmission member  124 ′ can be constructed generally similar to the second transmission member  124  ( FIG. 2 ) except that a sensor target  338 ′ can be coupled to the body  320  of the second transmission member  124 ′. The sensor target  338 ′ can include body portion  1070  and a target member  1080 . The body portion  1070  can be received in the bore  326  on a side of the teeth or splines  340  opposite the pilot portion  330  of the bore  326 . In the particular example provided, the body portion  1070  is a round plinth that is press-fit into the bore  326  and abutted against the teeth  340 , but those of ordinary skill in the art will appreciate that other shapes and/or attachment methods can be employed. For example, the body portion  1070  can be retained against the splines  340  by the sleeve  130 . The target member  1080  can be coupled to the body portion  1070  and can extend toward the controller assembly  64 ′. In the particular example provided, the target member  1080  is a rod that extends through the through-hole  466  in the plunger  128 ′, a through hole  1082  in the plunger backstop  192 ′ and the sensor aperture  1056  in the circuit board  1050 . When the anti-roll system  50 ′ is operated so that the first and second stabilizer bar members  60   a ′ and  60   b ′ are engaged to one another, the second transmission member  124 ′ can be positioned relatively closer to the first stabilizer bar member  60   a ′ so that the target member  1080  can be disposed in a first position (shown in solid line) in which the target member  1080  can be spaced apart from the sensor  1058 . Accordingly, the sensor  1058  can produce a first sensor signal that is indicative of the operation of the anti-roll system in an engaged mode. 
     When the anti-roll system  50 ′ is operated so that the first and second stabilizer bar members  60   a ′ and  60   b ′ are disengaged from one another, the second transmission member  124 ′ can be positioned relatively farther from the first stabilizer bar member  60   a ′ so that the target member  1080  can be disposed in a second position (shown in phantom) in which the target member  1080  can be disposed in-line with the sensor  1058 . Accordingly, the sensor  1058  can produce a second sensor signal that is indicative of the operation of the anti-roll system in a disengaged mode. 
     With reference to  FIG. 7 , a plots illustrating the application of electrical current and voltage to the coil assembly as a function of time are shown, as is a plot showing the location of the plunger  128 ′ ( FIG. 5 ) as a function of time. In the example provided, the plots of the electrical current (applied to the coil assembly  126 ), the electrical voltage (applied to the coil assembly  126 ) and the location of the plunger  128 ′ are indicated by reference numerals  2000 ,  2002  and  2004 , respectively, and electrical power is applied to the coil assembly  126  at time t 0 . With specific reference to the plot  2000  of the electrical current and the plot  2004  of the location of the plunger  128 ′ ( FIG. 5 ), current flowing through the coil assembly  126  ( FIG. 5 ) rises after time t 0  to a maximum current i max  to initiate movement of the plunger  128 ′ ( FIG. 5 ). Current flowing through the coil assembly  126  ( FIG. 5 ) drops from i max  to i n  at t n  when the plunger  128 ′ ( FIG. 5 ) has accelerated to maximum velocity. When the plunger  128 ′ ( FIG. 5 ) has traveled through its stroke, the current increases from i n  to i max . 
     In view of the above, the controller assembly  64 ′ ( FIG. 5 ) can monitor the magnitude of the electrical current that is supplied to the coil assembly  126  ( FIG. 5 ) for one or more purposes. The controller assembly  64 ′ ( FIG. 5 ) can employ such data to determine that the plunger  128 ′ ( FIG. 5 ) has moved, for example through the identification of changes in the slope of the plot of electrical current wherein the slope is first zero or positive, then negative and then positive. It will be appreciated that the calculation of the slope of a line is within the capabilities of one of ordinary skill in the art and as such, a discussion of the mathematics associated with this task need not be provided herein. 
     With additional reference to  FIG. 5 , the ability to determine that the plunger  128 ′ has moved can permit the controller assembly  64 ′ to apply a different amount of electrical power to the coil assembly  126 . In this regard, a first amount of electrical power can be input to the coil assembly  126  to move the plunger  128 ′ and thereafter a second, lower amount of electrical power can be input to the coil assembly  126  to maintain the plunger  128 ′ in its translated position. In the example provided, electrical power is supplied to the coil assembly  126  using a pulse-width-modulation technique and the amount of power that is transmitted to the coil assembly  126  is related to the duty cycle. Accordingly, it will be appreciated that a first duty cycle may be employed to move the plunger  128 ′ and a second, lower duty cycle may be employed to maintain the plunger  128 ′ in the translated position. Pulse-width-modulation techniques are well known to those of ordinary skill in the art and as such, further discussion is not required herein. 
     Moreover, the ability to monitor the slope of the plot  2000  of electrical current can provide diagnostic capabilities to the controller assembly  64 ′. For example, the position of the plunger  128 ′ can be identified by transmitting electrical power to the coil assembly  126  that is sufficient to move the plunger  128 ′ to its translated position. If a negative gradient or slope is detected in the plot  2000  of electrical current, it can be assumed that the plunger  128 ′ was in its returned position (opposite the translated position). If on the other hand a negative slope is not detected in the plot  2000  of electrical current, it can be assumed that the plunger  128 ′ was in its translated position. 
     In situations where a negative slope is not detected in the plot  2000  of electrical current but the sensor  1058  is producing the second sensor signal, which is indicative of the operation of the anti-roll system in a disengaged mode, the controller assembly  64 ′ can determine that the plunger  128 ′ is checked and can generate an appropriate fault message. In situations where a negative slope is not detected in the plot  2000  of electrical current but the sensor  1058  is producing the first sensor signal, which is indicative of the operation of the anti-roll system in an engaged mode, the controller assembly  64 ′ can determine that the plunger  128 ′ is checked and can generate an appropriate fault message. In situations where a negative slope is detected in the plot  2000  of electrical current but the sensor  1058  is producing the first sensor signal, the controller assembly  64 ′ can determine that the second transmission member  124 ′ is not able to move (e.g., torque locked). In situations where a negative slope is detected in the plot  2000  of electrical current but the sensor  1058  is producing the second sensor signal throughout this time, the controller assembly  64 ′ can determine that the sensor  1058  is not operating properly and can generate an appropriate fault message. 
     In situations where the first and second stabilizer bar members  62   a ′ and  62   b ′ are disengaged from one another and the coil assembly  126  is being supplied with the second amount of electrical power to maintain the plunger  128 ′ in its translated position, the controller assembly  64 ′ can perform a diagnostic check wherein the first amount of electrical power is supplied to the coil assembly  126  and the slope of the plot  2000  of electrical current is monitored. If a negative slope is detected in the plot  2000  of electrical current during this diagnostic check, the amount of power that is supplied to the coil assembly  126  was insufficient to maintain the plunger  128 ′ in its translated position. The controller assembly  64 ′ may generate an appropriate fault message and/or can change the parameters that control the amount of power that is supplied to the coil assembly  126  to maintain the plunger  128 ′ in its translated position. For example, the controller assembly  64 ′ could employ a look-up table to select a new set of parameters for the second duty cycle. 
     With reference to  FIG. 8 , an anti-roll system  50 ″ is illustrated to be similar to the anti-roll system  50 ′ of  FIG. 5 , except that the controller assembly  64 ″ can be a sealed unit that can be coupled to or disposed adjacent the cap member  190 ″. In the particular example provided, the controller  64 ″ is encapsulated in a plastic material that forms a controller housing  3000 . The controller housing can define a sensor aperture  3002  into which the sensor target  338 ″ can be received. In the particular example provided, the sensor target  338 ″ includes a non-magnetic body portion  1070 ″ and a magnetic target member  1080 ″, and a pair of sensors  1058   a ″ and  1058   b ″ are employed to sense a location of the target member  1080 ″ within the sensor aperture  3002 . The sensor  1058   a ″ can be configured to generate a first sensor signal when the target member  1080 ″ is disposed proximate thereto (to permit the controller  64 ″ to determine that the second transmission member  124 ′ ( FIG. 5 ) is in the first position). The sensor  1058   b ″ can be configured to generate a second sensor signal when the target member  1080 ″ is disposed proximate thereto (to permit the controller  64 ″ to determine that the second transmission member  124 ′ ( FIG. 5 ) is in the second position). It will be appreciated that the controller  64 ″ could include a third sensor between the sensors  1058   a ″ and  1058   b ″ to identify situations in which the second transmission member  124 ′ ( FIG. 5 ) is positioned between the first and second positions. It will also be appreciated that the packaging of the controller (e.g., controller  64 ″) in the cap member (e.g., cap member  190 ″) as shown in  FIGS. 5 and 8  is advantageous in that it helps protect the controller from damage caused by impacts (e.g., rocks) and can help to shield the controller from electromagnetic interference (EMI). 
     While specific examples have been described in the specification and illustrated in the drawings, it will be understood by those of ordinary skill in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the present disclosure as defined in the claims. Furthermore, the mixing and matching of features, elements and/or functions between various examples is expressly contemplated herein so that one of ordinary skill in the art would appreciate from this disclosure that features, elements and/or functions of one example may be incorporated into another example as appropriate, unless described otherwise, above. Moreover, many modifications may be made to adapt a particular situation or material to the teachings of the present disclosure without departing from the essential scope thereof. Therefore, it is intended that the present disclosure not be limited to the particular examples illustrated by the drawings and described in the specification as the best mode presently contemplated for carrying out this invention, but that the scope of the present disclosure will include any embodiments falling within the foregoing description and the appended claims.