Abstract:
Methods and apparatus are provided for attenuating vibrations in the header of a convertible vehicle. The apparatus includes a fluid damper configured to be coupled to a header of a convertible vehicle and an accelerometer for sensing vibrations in the header and providing a signal to adjust the fluid damper thereby attenuating the vibrations. A method is provided which includes receiving a signal indicating a vibration in a header of a convertible vehicle and adjusting a fluid damper coupled to the header in response to the signal thereby attenuating the vibration.

Description:
TECHNICAL FIELD 
       [0001]    The technical field generally relates to vibration damping, and more particularly, to a system and method for controlling/regulating an electronically controlled damping system in a convertible vehicle. 
       BACKGROUND 
       [0002]    Convertible motor vehicles have a roof that can be manually or automatically transferred from a closed position to an open position (and vice versa). For example, some convertible vehicles are equipped with a folding roof that consists of a flexible material (or “soft-top”) which folds into a storage area when the roof is in the open position. Other convertible vehicles have several roof segments (or “retractable hardtop”), in which the roof segments are folded on top of one another in the open position and the stack of segments can be stowed, for example, in the trunk or behind the rear seat. 
         [0003]    With respect to convertible vehicles, it is known that the driving dynamics of the vehicle change depending on whether the vehicle roof is in its open position or in its closed position. The main reasons for this variability in the driving dynamics are the changed bending and torsional rigidity of the vehicle body, as well as a shift of the vehicle masses that is caused by the changed position of the vehicle roof. For example, when the vehicle roof is opened, the front header that supports the windshield of the convertible vehicle is no longer supported by the retracted roof. In this case, interaction between the vehicle suspension system and road conditions may cause lateral vibrations (or shake) in the vehicle front header that operators of the vehicle may find objectionable. 
         [0004]    Conventionally, passive vibration absorbers have been attached to the header in an attempt to attenuate (absorb) the unwanted vibrations. However, lateral shake is a non-linear response that limits the effectiveness of passive absorbers since passive absorbers are tuned to a predetermined mass for selected driving conditions. 
         [0005]    Accordingly, it is desirable to provide a vibration attenuation system for convertible vehicles that is effective at attenuating lateral vibrations in the header. In addition, it is desirable to have such a system be closed loop so as to be responsive to the non-linear nature of lateral shake. Furthermore, other desirable features and characteristics of the present invention will become apparent from the subsequent detailed description and the appended claims, taken in conjunction with the accompanying drawings and the foregoing technical field and background. 
       SUMMARY 
       [0006]    An apparatus is provided for attenuating vibrations in the header of a convertible vehicle. In one embodiment, the apparatus includes a fluid damper configured to be coupled to a header of a convertible vehicle and an accelerometer for sensing vibrations in the header and providing a signal to adjust the fluid damper thereby attenuating the vibrations. 
         [0007]    A method is provided for attenuating vibrations in the header of a convertible vehicle. In one embodiment, the method includes receiving a signal indicating a vibration in a header of a convertible vehicle and adjusting a fluid damper coupled to the header in response to the signal thereby attenuating the vibration. 
     
    
     
       DESCRIPTION OF THE DRAWINGS 
         [0008]    The exemplary embodiments will hereinafter be described in conjunction with the following drawing figures, wherein like numerals denote like elements, and wherein: 
           [0009]      FIG. 1  is top plan view of a convertible vehicle in accordance with an embodiment; 
           [0010]      FIG. 2  is cross-sectional view of the fluid damper of  FIG. 1  in accordance with a first embodiment; 
           [0011]      FIG. 3  is cross-sectional view of the fluid damper of  FIG. 1  in accordance with another embodiment; and 
           [0012]      FIG. 4  is flow diagram illustrating a method in accordance with an embodiment. 
       
    
    
     DETAILED DESCRIPTION 
       [0013]    The following detailed description is merely exemplary in nature and is not intended to limit the application and uses. Furthermore, there is no intention to be bound by any expressed or implied theory presented in the preceding technical field, background, brief summary or the following detailed description. 
         [0014]    In this document, relational terms such as first and second, and the like may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Numerical ordinals such as “first,” “second,” “third,” etc. simply denote different singles of a plurality and do not imply any order or sequence unless specifically defined by the claim language. 
         [0015]    Additionally, the following description refers to elements or features being “connected” or “coupled” together. As used herein, “connected” may refer to one element/feature being directly joined to (or directly communicating with) another element/feature, and not necessarily mechanically. Likewise, “coupled” may refer to one element/feature being directly or indirectly joined to (or directly or indirectly communicating with) another element/feature, and not necessarily mechanically. However, it should be understood that, although two elements may be described below, in one embodiment, as being “connected,” in alternative embodiments similar elements may be “coupled,” and vice versa. Thus, although the schematic diagrams shown herein depict example arrangements of elements, additional intervening elements, devices, features, or components may be present in an actual embodiment. 
         [0016]    Finally, for the sake of brevity, conventional techniques and components related to vehicle electrical and mechanical parts and other functional aspects of the system (and the individual operating components of the system) may not be described in detail herein. Furthermore, the connecting lines shown in the various figures contained herein are intended to represent example functional relationships and/or physical couplings between the various elements. It should be noted that many alternative or additional functional relationships or physical connections may be present in an embodiment of the invention. It should also be understood that  FIGS. 1-3  are merely illustrative and may not be drawn to scale. 
         [0017]      FIG. 1  is a simplified schematic representation of an embodiment of a convertible vehicle  100  according to exemplary embodiments. Although the vehicle  100  is illustrated as a purely electric vehicle, the techniques and concepts described herein are also applicable to hybrid electric vehicles or vehicles employing internal combustion engines. The vehicle  100  may be two-wheel drive (2WD), four-wheel drive (4WD), or all-wheel drive (AWD). In internal combustion or hybrid electric vehicle embodiments, the convertible vehicle  100  may also incorporate any one of, or combination of, a number of different types of engines, such as, for example, a gasoline or diesel fueled combustion engine, a flex fuel vehicle (FFV) engine (i.e., using a mixture of gasoline and alcohol), a gaseous compound (e.g., hydrogen and/or natural gas) fueled engine in addition to an electric motor. 
         [0018]    The illustrated embodiment of the convertible vehicle  100  includes, without limitation: a plug-in charging port  102  coupled to an energy storage system  104 ; a control module  106  coupled to a generator  108  for charging the energy storage system  104 ; and an inverter  110  coupled to the energy storage system  104  for providing AC power to a powertrain  112  via a cable  114 . The powertrain  112  includes an electric motor  116  and a transmission  118  for driving wheels  120  to propel the convertible vehicle  100 . 
         [0019]    The plug-in charging port  102  may be configured as any suitable charging interface, and in one embodiment, comprises a charging receptacle compatible with the J1772 standard, which receives a charging cable with compatible plug (not shown). The energy storage system  104  may be realized as a rechargeable battery pack having a single battery module or any number of individual battery cells operatively interconnected (e.g., in series or in parallel), to supply electrical energy. A variety of battery chemistries may be employed within the energy storage system  104  such as, lead-acid, lithium-ion, nickel-cadmium, nickel-metal hydride, etc. 
         [0020]    The control module  106  may include any type of processing element or vehicle controller, and may be equipped with nonvolatile memory, random access memory (RAM), discrete and analog input/output (I/O), a central processing unit, and/or communications interfaces for networking within a vehicular communications network. The control module  106  is coupled to the energy storage system  104 , the generator  108 , the inverter  110  and the powertrain  112  and controls the flow of electrical energy between the these modules depending on a required power command, the state of charge of the energy storage system  104 , etc. 
         [0021]    As noted above, in hybrid-electric embodiments, the powertrain  112  includes an electric motor  116  and a transmission  118  configured within a powertrain housing. The electric motor  16  includes a rotor and stator (not shown) operatively connected via the transmission  118  to at least one of the wheels  120  to transfer torque thereto for propelling the vehicle  100 . It will be appreciated that in hybrid-electric embodiments, the powertrain  112  may be implemented as a series hybrid-electric powertrain or as a parallel hybrid-electric powertrain. 
         [0022]    As illustrated in  FIG. 1 , the convertible vehicle  100  is shown with the roof in the open position with the roof stored in a storage area  122 . A front header  124  forms part of a frame  126  that supports the windshield  128  and various amenities such as sun visors, etc. According to various embodiments, the header  124  of the convertible vehicle  100  is equipped with a fluid damper  130 . As will be discussed in more detail below, the fluid damper  130  is a dynamically adjustable fluid damper providing an electrically controlled mass that attenuates (absorbs) vibrations in the header  124  such as lateral vibrations. Sensors may be integrated with the fluid damper  130  or coupled to the header  124  to provide a signal indicating the vibrations are present in the header. In this way, a closed-loop control system is provided to achieve active and dynamic vibration damping. 
         [0023]      FIG. 2  is a cross-sectional view of an exemplary embodiment of an adjustable fluid damper  130 . The illustrated embodiment comprises a Magneto-Rheological damper contained in a housing  200  that is coupled to the header  124  via mounting brackets  202 . A reservoir  204  is defined within the housing  200  by a diaphragm  206 . The reservoir  204  contains a Magneto-Rheological fluid  208  that has the property of changing its viscosity responsive to an electromagnetic field applied across the reservoir or an electric current passing through the Magneto-Rheological fluid  208 . In some embodiments, the Magneto-Rheological fluid  208  consists of an approximately twenty percent iron fluid (e.g., FE 20% by volume fraction) that will undergo a viscosity change responsive to an electric field or current. Above the diaphragm  206 , a base mass  210  is mounted to the upper portion of the housing  200  by mounts  212 . In a non-limiting embodiment, the base mass  210  has a mass in the range of 0.5-1.0 kilograms. Together the base mass  210  and the Magneto-Rheological fluid  208  provide an electrically adjustable (or tunable) mass effective at attenuating (absorbing) vibrations in the header, including lateral vibrations (indicated by the double arrow  214 ) in the exemplary range of 11-22 Hertz. This affords an advantage over passive absorbers in that the overall size (or “package”) of the fluid damper is reduced. 
         [0024]    According to various embodiments, a closed-loop control system is provided for the fluid damper  130  by incorporating sensors or accelerometers to provide a signal for adjusting the fluid damper  130 . In some embodiments, the sensor  216  is integrated within the housing  200 . In some embodiments, the sensor  218  is coupled to the header  124 . In some embodiments, the sensor  220  can be placed on the housing  200  at an external bottom portion. In some embodiments, the sensor  222  can be placed on the housing  200  at an external side portion. Regardless of the placement of the sensor  222 , a signal  224  is provided to the fluid damper  130  causing the Magneto-Rheological fluid  208  to change its viscosity. In some embodiments connections  226  comprise electromagnets within the reservoir  204  that apply an electromagnetic field across the Magneto-Rheological fluid  208  to change its viscosity. In some embodiments, connections  226  comprise electrodes for passing a current through the Magneto-Rheological fluid  208  to change its viscosity. Additionally or alternately, the fluid damper  130  could be controlled (or also controlled) by the control module ( 106  of  FIG. 1 ) via connection  228 . In this way, factors such as the speed of the convertible vehicle  100  or the revolutions (e.g., revolution per minute (RPM)) of the engine ( 116  of  FIG. 1 ) or transmission ( 118  of  FIG. 1 ) can be taken into account for adjusting the fluid damper  130 . 
         [0025]      FIG. 3  is a cross-sectional view of another exemplary embodiment of an adjustable fluid damper  130 . As will be appreciated, the adjustable fluid damper  130  can be operably fastened to the header via a mounting bracket (not shown in  FIG. 3 ) and using adhesives, mechanical fasteners, riveting, welding, etc. The illustrated embodiment comprises a servo-controlled fluid damper comprising a main orifice  300  and an equalizing orifice  302  separated by a diaphragm  304 . A coil  306 , armature spring  308  and valve plate  310  control how much hydrolytic fluid passes from a port  312  into the main orifice  300  via a pilot orifice  314 . By controlling the volume of hydraulic fluid in the main orifice  300 , the mass of the servo-controlled fluid damper is adjusted thereby attenuating vibrations in the header ( 124  of  FIG. 1 ) of the convertible vehicle ( 100  of  FIG. 1 ). 
         [0026]      FIG. 4  illustrates a flow diagram useful for understanding the method  400  for attenuating vibrations in the header ( 124  of  FIG. 1 ) of the convertible vehicle ( 100  of  FIG. 1 ). The various tasks performed in connection with the method  400  of  FIG. 4  may be performed by software, hardware, firmware, or any combination thereof. For illustrative purposes, the following description of the method  400  of  FIG. 4  may refer to elements mentioned above in connection with  FIGS. 1-3 . In practice, portions of the method of  FIG. 4  may be performed by different elements of the described system. It should also be appreciated that the method of  FIG. 4  may include any number of additional or alternative tasks and that the method of  FIG. 4  may be incorporated into a more comprehensive procedure or process having additional functionality not described in detail herein. Moreover, one or more of the tasks shown in  FIG. 4  could be omitted from an embodiment of the method  400  of  FIG. 4  as long as the intended overall functionality remains intact. 
         [0027]    The routine (method  400 ) begins in step  402  where a signal ( 224  or  228  of  FIG. 2 ) is received indicating that a vibration exists in the header ( 124  of  FIG. 1 ) of the convertible vehicle ( 100  of  FIG. 1 ). The signal can be provided by sensors or accelerometers position in various positions, some of which were described above in connection with  FIG. 2 . Additionally or alternately, the signal could be provided by the control module ( 106  of  FIG. 1 ). In step  404 , the fluid damper ( 130  of  FIG. 2 ) is adjusted in response to this signal effectively adjusting its mass (the collective mass provided by the base mass  210  and the viscosity of the Magneto-Rheological fluid  208 ) to attenuate (absorb) some or all of the vibration. This may be achieved by varying an electromagnetic field across the Magneto-Rheological fluid  208  or modifying a current passing through the Magneto-Rheological fluid  208 . In step  406 , it may be determined whether the vibration(s) have been effectively attenuated. In some embodiments, this is determined by the continued reception or absence of the signal. In some embodiments, the signal (if still present) is compared to a threshold to determine if the vibration(s) have been attenuated below a level perceivable by the operator of the vehicle  100 . If so, the routine ends (step  408 ) until the signal is received yet again in step  402 . If not, the routine returns to step  404  for continued adjustment of the fluid damper  130 . In this way, a closed-loop control system is provided for dynamic and continuous attenuation of vibrations. 
         [0028]    While at least one exemplary embodiment has been presented in the foregoing detailed description, it should be appreciated that a vast number of variations exist. It should also be appreciated that the exemplary embodiment or exemplary embodiments are only examples, and are not intended to limit the scope, applicability, or configuration of the disclosure in any way. Rather, the foregoing detailed description will provide those skilled in the art with a convenient road map for implementing the exemplary embodiment or exemplary embodiments. It should be understood that various changes can be made in the function and arrangement of elements without departing from the scope of the appended claims and the legal equivalents thereof.