Abstract:
A damped steering assembly includes a steering wheel for operative attachment to a steering column of the vehicle and a suspended member connected to the steering wheel. The damped steering assembly also includes a mass connected to the suspended member. The damped steering assembly further includes at least one damping element positioned on the suspended member to cooperate therewith to actively damp vibration from the steering wheel.

Description:
CROSS-REFERENCE TO RELATED APPLICATION(S)  
       [0001]    The present application claims priority from provisional application Serial No. 60/210,869, filed Jun. 9, 2000. 
     
    
     
       TECHNICAL FIELD  
         [0002]    The present invention relates generally to steering assemblies for vehicles and, more particularly, to a damped steering assembly for a vehicle.  
         BACKGROUND OF THE INVENTION  
         [0003]    It is known to provide a steering assembly for wheels of a vehicle. The steering assembly typically includes a steering wheel connected to a steering column, which is operatively connected to wheels of the vehicle. It is also known that a driver of a vehicle grips the steering wheel to steer the vehicle. It is further known that most vehicles experience driving conditions having vibrational input to the vehicle. These vibrational inputs include idle shake, rough road, and vehicle system resonance.  
           [0004]    One commercial approach to damping the vibration in the steering assembly is to use a rubber mounted damper. Currently, the rubber-mounted damper is added to an inside of a hub area of the steering wheel for vibration damping of the natural frequency of a particular vehicle. However, the rubber-mounted damper is adversely affected by temperature or time. In addition, the rubber-mounted damper can only dampen a target frequency with a +/− 15%. Further, the rubber mounted damper fatigues and changes the target frequency that the damper will cancel out.  
           [0005]    It is desirable to provide a damper on a steering assembly for a vehicle to damp vibration. It is also desirable to provide a damped steering assembly for a vehicle. It is further desirable to damp vibration in a steering assembly for a vehicle that eliminates the use of rubber-mounted dampers.  
         SUMMARY OF THE INVENTION  
         [0006]    It is, therefore, one object of the present invention to provide a damped steering assembly for a vehicle.  
           [0007]    It is another object of the present invention to provide a steering assembly with a damper that eliminates the use of a rubber-mounted damper.  
           [0008]    To achieve the foregoing objects, the present invention is a damped steering assembly for a vehicle. The damped steering assembly includes a steering wheel for operative attachment to a steering column of the vehicle and a suspended member connected to the steering wheel. The damped steering assembly also includes a mass connected to the suspended member. The damped steering assembly further includes at least one damping element positioned on the suspended member to cooperate therewith to actively damp vibration from the steering wheel.  
           [0009]    One advantage of the present invention is that an improved damped steering assembly is provided with a damper to actively damp vibration generated by the vehicle. Another advantage of the present invention is that the damped steering assembly eliminates the rubber-mounted damper, thereby providing a damper, which is not adversely affected by temperature or time. Yet another advantage of the present invention is that the damped steering assembly reduces vibration to the driver, thereby providing a vibration free steering wheel and improving ride and comfort quality for the driver. Still another advantage of the present invention is that the damped steering assembly has a damper that is capable of canceling a broad spectrum of frequencies. A further advantage of the present invention is that the damped steering assembly has a damper that resists fatigue over time.  
           [0010]    Other objects, features, and advantages of the present invention will be readily appreciated, as the same becomes better understood, after reading the subsequent description taken in conjunction with the accompanying drawings. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0011]    [0011]FIG. 1 is a perspective view of a damped steering assembly, according to the present invention, illustrated in operational relationship with a vehicle.  
         [0012]    [0012]FIG. 2 is an elevational view of the damped steering assembly of FIG. 1.  
         [0013]    [0013]FIG. 3 is a perspective view of a portion of the damped steering assembly of FIGS. 1 and 2.  
         [0014]    [0014]FIG. 4 is a partial perspective view of the damped steering assembly of FIGS. 1 and 2. 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0015]    Referring to the drawings and in particular FIG. 1, one embodiment of a damped steering assembly  10 , according to the present invention, is shown for a vehicle (partially shown) such as a motor vehicle, generally indicated at  12 . The motor vehicle  12  includes an engine compartment  14  and occupant compartment  16 . The occupant compartment  16  is accessible via a door  18  and includes a seat  20  in which an occupant, namely the driver, may sit. The damped steering assembly  10  includes a steering wheel  22  spaced from an instrument panel  24  in the occupant compartment  16 . The damped steering assembly  10  includes a steering column  26  connected to the steering wheel  22  and extending through the occupant compartment  16  into the engine compartment  14 . The steering column  26  includes a shifting lever  27  used to control a transmission (not shown) of the motor vehicle  12 . It should be appreciated that the steering column  26  is operatively connected to wheels (not shown) of the vehicle. It should also be appreciated that an operator&#39;s hands (not shown) typically grip the steering wheel  22  to guide the vehicle  12  in the desired direction.  
         [0016]    As illustrated in FIGS. 1 through 4, the steering wheel  22  includes a frame  28  that defines the shape of the steering wheel  22 . Preferably, the frame  28  is made from a metal material such as magnesium. The steering wheel  22  includes a hub or inner rim  30 , an outer rim  32  circumscribing the inner rim  30  and at least one spoke  34  interconnecting the inner rim  30  with the outer rim  32 . The frame  28  of the inner rim  30 , outer rim  32 , and spoke  34  is integral and one-piece. It should be appreciated that the frame  28  is conventional and known in the art.  
         [0017]    The steering wheel  22  also includes a padding member  36  that encloses the frame  28 . The padding member  36  cushions the frame  28  to enhance the comfort of the steering wheel  22  for the operator&#39;s hands. In this example, the padding member  36  is a cushioning material such as urethane. Advantageously, the padding member  36  may be molded. It should be appreciated that the padding member  36  is conventional and known in the art.  
         [0018]    The damped steering assembly  10  includes a suspended member  38  connected to the inner rim  30 . The suspended member  38  has a base  39 , which is generally rectangular and planar in shape. The base  39  has an aperture  39   a  extending therethrough to receive a toothed sleeve  39   b  and a plurality of apertures  39   c  extending therethrough to receive fasteners  39   d  to secure the base  39  to the inner rim  30 . The suspended member  38  has a pair of opposed support arms  40  extending outwardly and generally perpendicular to the base  39 . The suspended member  38  also has a flange  42  extending general parallel to the base mass  39  and perpendicular to the support arm  40 . The flanges  42  include an aperture  43  extending therethrough for a function to be described. The suspended member  38  is made from a metal material such as spring steel or a composite material. It should be appreciated that the suspended member  38  is operatively connected via the toothed sleeve  39   a  to the inner rim  30  and to a shaft (not shown) of the steering column  26  of the vehicle  12 . It should be appreciated that the base  39  is supported by two support arms  40  with known stiffnesses characterized by EI (material modulus times section modulus). It should also be appreciated that the steering column  26  is conventional and known in the art.  
         [0019]    The damped steering assembly  10  also includes at least one, preferably a plurality of, more preferably four, damping elements  44  positioned on the suspended member  38 . The damping element  44  is of a piezoelectric type. An example of the damping element  44  is disclosed in U.S. Pat. Nos. 5,656,882 and 5,687,462 to Lazarus et al. and assigned to Active Control Experts, Inc., of Cambridge Mass., the disclosures of which are hereby incorporated by reference. The damping element  44  is a QUICKPACK® piezoelectric actuator which is commercially available from Active Control Experts, Inc. The damping element  44  is a generally planar member that extends longitudinally and transversely a suitable amount to a desired surface area of the suspended member  38 . The damping element  44  is attached directly onto a surface of the support arm  40  by suitable means such as an adhesive. Preferably, a pair of damping elements  44  are attached to opposed locations on each of the support arms  40  of the suspended member  38  to provide tension and compression on each side of the support arms  40 .  
         [0020]    The damped steering assembly  10  includes a mass  46  connected to the suspended member  38 . The mass  46  is generally rectangular in shape. The mass  46  includes a central recess  48  having a general “U” shape to allow the shaft of the steering column  26  to extend therethough and connect to the toothed sleeve  39   b . The mass  46  also includes a side recess  50  spaced from the central recess  48  on both sides thereof. The side recess  50  has a general “U” shape to allow the arms  40  of the suspended member  38  to extend therethrough. The mass  46  is secured to the flanges  42  of the suspended member  38  by suitable means such as fasteners  52  extending through apertures (not shown) in the mass  46  and the apertures  43  in the flanges  42  and engaging the flanges  42 . The mass  46  is made of a metal material such as lead.  
         [0021]    The damped steering assembly  10  further includes a power source, such as the controller  54 , electrically connected by wires (not shown) to each of the damping elements  44 . The controller  54  has an amplifier and control (not shown) to apply a voltage to the damping elements  44  to produce active damping.  
         [0022]    The damped steering assembly  10  includes an accelerometer  56  connected to the steering wheel  22  and the controller  46 . The accelerometer  56  is connected to the inner rim  30  by suitable means such as an adhesive. It should be appreciated that the accelerometer  56  is conventional and known in the art.  
         [0023]    In operation, the vehicle  12  produces vibration, which is generated at the natural frequency of the particular vehicle  12 , for example between 37 Hz to 38 Hz, at engine idle position. In the damped steering assembly  10 , the accelerometer  56  measures the vibrational inputs coming into the steering wheel  22  and feeds that to the controller  54 . The controller  54  sends an 180 out of phase signal through the amplifier that applies a voltage to the damping elements  44 , which cause them to bend and displace. The displacement of the damping elements  44  causes the suspended member  38  to move out of phase with the vibrational input and cause active damping of the vibrations in the steering wheel  22  to a reduced level. This serves to cancel out the input vibration, thus providing a vibration free feel of the steering wheel  22 . It should be appreciated that the number and location of the damping elements  44  can be varied for different reduction levels of the vibration.  
         [0024]    The present invention has been described in an illustrative manner. It is to be understood that the terminology, which has been used, is intended to be in the nature of words of description rather than of limitation.  
         [0025]    Many modifications and variations of the present invention are possible in light of the above teachings. Therefore, within the scope of the appended claims, the present invention may be practiced other than as specifically described.