Abstract:
A friction control device includes a slotted shield through which an active material layer selectively expands. A system includes a second component movable with respect to a first component; a friction control device between the first component and the second component, the friction control device including: an active material layer; and a slotted shield through which the active material layer selectively expands through. A method for controlling a frictional interface between a first component and a second component, includes selectively expanding an active material through a multiple of slots.

Description:
BACKGROUND 
     The present disclosure relates generally to methods and devices for controlling and varying frictional force levels at an interface. 
     Various systems utilize actuators to control friction at an interface such as within a clutch, brakes, bearings, suspension, steering and others. Such actuators may be complicated and relatively heavy in weight. Further, other operational or functional requirements such as limited packaging space may prevent effective control of frictional force levels. 
     SUMMARY 
     A friction control device according to one disclosed non-limiting embodiment of the present disclosure includes an active material layer and a slotted shield with a multiple of slots through which at least a portion of the active material layer is selectively operable to expand. 
     A system according to another disclosed non-limiting embodiment of the present disclosure includes a second component movable with respect to a first component; a friction control device between the first component and the second component, the friction control device including: an active material layer; and a slotted shield with a multiple of slots through which at least a portion of the active material layer is selectively operable to change a frictional force between the first component and the second component. 
     A method for controlling a frictional interface between a first component and a second component, according to another disclosed non-limiting embodiment of the present disclosure includes selectively expanding an active material through a multiple of slots to change a frictional force between the first component and the second component. 
     The foregoing features and elements may be combined in various combinations without exclusivity, unless expressly indicated otherwise. These features and elements as well as the operation thereof will become more apparent in light of the following description and the accompanying drawings. It should be understood, however, the following description and drawings are intended to be exemplary in nature and non-limiting. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Various features will become apparent to those skilled in the art from the following detailed description of the disclosed non-limiting embodiment. The drawings that accompany the detailed description can be briefly described as follows: 
         FIG. 1  is a schematic view of a friction control device according to one disclosed non-limiting embodiment; 
         FIG. 2  is a schematic view of the friction control device in an activated condition; 
         FIG. 3  is a schematic view of the friction control device in a deactivated condition; 
         FIG. 4  is a schematic view of a friction control device example slot geometry for the friction control device; 
         FIG. 5  is a schematic view of a slot pattern for the friction control device according to one disclosed non-limiting embodiment; 
         FIG. 6  is a schematic view of a slot pattern for the friction control device according to another disclosed non-limiting embodiment; 
         FIG. 7  is a schematic view of a friction control device in a rotary application; 
         FIG. 8  is a graphical representation of a frictional force level with respect to an actuation signal provided to the friction control device; 
         FIG. 9  is a graphical representation of a relative motion control with respect to the actuation signal provided to the friction control device; 
         FIG. 10  is a schematic view of a slot orientation in the friction control device for a rotary application; 
         FIG. 11  is a schematic view of a steering wheel system application controlled by the friction control device; 
         FIG. 12  is a graphical representation of a selective steering wheel resistance feel provided by the friction control device; and 
         FIG. 13  is a schematic view of a suspension system application controlled by the friction control device. 
     
    
    
     DETAILED DESCRIPTION 
       FIG. 1  schematically illustrates a friction control device  20 . The friction control device  20  generally includes an active material layer  22  and a slotted shield  24 . Suitable active materials for the active material layer  22  include, without limitation, shape memory alloys (SMA), ferromagnetic shape memory alloys (MSMA), electroactive polymers (EAP), piezoelectric materials, magnetorheological (MR) elastomers, electrorheological (ER) elastomers, electrostrictive materials, magnetostrictive materials, and the like. Depending on the particular active material, the activation signal for the active material layer  22  can take the form of, without limitation, an electric current, an electric field (voltage), a temperature change, a magnetic field, a mechanical loading or stressing (such as stress induced superelasticity in SMA), a chemistry or pH change, and the like. 
     When actuated, the active material layer  22  may expand to, in one example, twice its thickness, but a variable thickness is readily achieved through control of the actuation signal such as through a variable current. Alternatively, the active material layer  22  is selectively contracted in response to the actuation signal. 
     The slotted shield  24 , according to one disclosed non-limiting embodiment includes a multiple of slots  26  arranged through which the active material layer  22  extends when in the actuated condition ( FIG. 2 ). It should be appreciated that although the multiple of slots  26  in the disclosed non-limiting embodiment are arranged in parallel, other relationships will benefit herefrom. 
     The multiple of slots  26  operate to stabilize and focus the active material layer  22  when actuated. That is, the active material layer  22  selectively extends at least partially through the multiple of slots  26  when in an actuated condition ( FIG. 2 ) as compared to a deactivated condition ( FIG. 3 ) in which the active material layer  22  does not extend—or extends to a lesser extent—through the multiple of slots  26  as compared to the actuated condition. The friction control device  20  thereby controls a frictional interface  30  to change a frictional force between a first component  32  and a second component  34 . 
     The multiple of slots  26  may include slots of various widths W and/or lengths L  26 - 1 ,  26 - 2 ,  26 - 3  and combinations thereof ( FIG. 4 ). That is, at least one of the multiple of slots  26  may includes a first slot having a width W and/or a length L different than a second of the multiple of slots  26 . It should be appreciated that “slots” as defined herein includes various extended apertures of various configurations and geometries. Further, the multiple of slots  26  may be arranged in various patterns other than a rectilinear pattern such as, for example, a triangle ( FIG. 5 ), a chevron ( FIG. 6 ) or other shapes and/or patterns may be provided to further tailor the frictional force provided by the frictional interface  30 . 
     With reference to  FIG. 7 , a friction control device  20 A is located at a rotational frictional interface  40  between a first component  32 A and a second component  34 A. In this disclosed non-limiting embodiment, the first component  32 A rotates relative to the second component  34 A about an axis A. Selective actuation of the friction control device  20 A operates to control the frictional force between the components  32 A,  34 A with respect to the activation signal ( FIG. 8 ). This results in relative motion control, e.g., torque/force control with respect to the activation signal ( FIG. 9 ). For example, an increased voltage results in an increased frictional force at the rotational frictional interference. It should be appreciated that particular slot shapes and arrangements may be selected to further tailor the frictional force. 
     In this disclosed non-limiting embodiment, the first component  32 A rotates relative to the second component  34 A about the axis A and the slots  26 A are arranged transverse to the direction of rotation (illustrated schematically by arrow R). That is, the slots  26 A are arranged generally parallel to the axis A. In another disclosed non-limiting embodiment, the first component  32 B slides relative to the second component  34 B along an axis B and the slots  26 B of the friction control device  20 B are transverse to the axis B ( FIG. 10 ). 
     With reference to  FIG. 11 , the friction control device  20 A may be utilized in an example steering system  50  application to facilitate a desired steering resistance feel in response to the activation signal ( FIG. 12 ). 
     With reference to  FIG. 13 , the friction control device  20 B may be utilized in an example suspension system  60  application to facilitate a desired suspension effect such as hard, soft, etc., in response to the activation signal. 
     It should be appreciated that these are but illustrated examples, and that various systems may benefit herefrom. 
     It should be understood that relative positional terms such as “forward,” “aft,” “upper,” “lower,” “above,” “below,” and the like are with reference to the normal operational attitude of the vehicle and should not be considered otherwise limiting. 
     Although the different non-limiting embodiments have specific illustrated components, the embodiments of this invention are not limited to those particular combinations. It is possible to use some of the components or features from any of the non-limiting embodiments in combination with features or components from any of the other non-limiting embodiments. 
     It should be understood that like reference numerals identify corresponding or similar elements throughout the several drawings. It should also be understood that although a particular component arrangement is disclosed in the illustrated embodiment, other arrangements will benefit herefrom. 
     Although particular step sequences are shown, described, and claimed, it should be understood that steps may be performed in any order, separated or combined unless otherwise indicated and will still benefit from the present disclosure. 
     The foregoing description is exemplary rather than defined by the limitations within. Various non-limiting embodiments are disclosed herein, however, one of ordinary skill in the art would recognize that various modifications and variations in light of the above teachings will fall within the scope of the appended claims. It is therefore to be understood that within the scope of the appended claims, the disclosure may be practiced other than as specifically described. For that reason the appended claims should be studied to determine true scope and content.