Patent Publication Number: US-2007099465-A1

Title: Assembly for a steering system of a motor vehicle

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
      This application claims the benefit of DE 10 2005 053 183.0 filed Nov. 3, 2005. The disclosure of the above application is incorporated herein by reference.  
     FIELD  
      The present disclosure relates to an assembly for a steering system of a motor vehicle, comprising an integrated support on which a steering wheel hub of a steering wheel is pivoted.  
     BACKGROUND  
      The statements in this section merely provide background information related to the present disclosure and may not constitute prior art.  
      An assembly of this type is known from U.S. Pat. No. 3,744,817. The assembly disclosed there uses ball bearings or tapered roller bearings to allow a smooth rotation of the steering wheel about the stationary support.  
     SUMMARY  
      It is the object of the present disclosure to create an assembly for a steering system of a motor vehicle, which is particularly easy to mount.  
      This object is achieved according to the disclosure in that a rotor element is provided for mounting the steering wheel hub of the steering wheel on the support. The rotor element allows a particularly flexible installation of the assembly. As a result, the rotor element can serve not only the accommodation of the steering wheel, but also the accommodation of further components, as will be described hereinafter.  
      The accommodation of further components is particularly facilitated when the rotor element is configured substantially in a sleeve shape. The sleeve-shaped rotor element can be used, for example, to arrange an elastic element. The rotor element and the steering wheel hub of the steering wheel can be mutually connected such that a rotation angle offset becomes possible between the rotor element and the steering wheel hub of the steering wheel. An elastic element of this type is described in the simultaneously submitted German patent application “Vorrichtung für ein Lenksystem eines Kraftfahrzeugs” [Device for a Steering System for a Motor Vehicle] (German patent application number: 10 2005 053 181.4) by the same applicant. The disclosure of this application is hereby referred to and incorporated by reference in its entirety.  
      The rotor element can also be designed, for example, to accommodate a gearbox element, such as a gear wheel, which is part of a gearbox for transmitting the rotations of the steering wheel onto a steering shaft. The greater the number of components that the rotor element can accommodate, the more complex and the larger the sub-assembly group can be, which can be provided for the motor vehicle for final assembly. This makes it possible to subject these complex sub-assembly groups to comprehensive quality controls, particularly to be able to precisely inspect the individual functions of the sub-assembly group. During final assembly of the motor vehicle and the subsequent final control, time can then be saved.  
      According to an advantageous further development of the disclosure, the steering wheel and/or the steering wheel hub is non-rotatably connected to a first coding element, which is part of a rotation angle sensor arrangement and/or a torque sensor arrangement. Accordingly, the rotor element can be designed to accommodate a second coding element, which is part of a rotation angle sensor arrangement and/or torque sensor arrangement. This arrangement of the coding elements allows a space-saving integration of a rotation angle sensor and/or of a torque sensor in an assembly close to the steering wheel. This is also described in the simultaneously submitted German patent application by the same applicant with the title “Vorrichtung zur Anordnung in einem Lenksystem eines Fahrzeugs” [Device for Arrangement in a Steering System of a Motor Vehicle] (German patent application number: DE 10 2005 053 180.6). The disclosure of this application is hereby referred to and incorporated by reference in its entirety.  
      An advantageous further development of the disclosure provides that an air bag unit is attached to the support such that it is decoupled from the rotation of the steering wheel. This has the advantage that the air bag unit can be fixed, so that it does not have to be designed rotation-symmetrically in order to act optimally during an accident. A fixed or “static” air bag unit also has the advantage that the use of a clock spring for the electrical contact to the air bag unit is not required. The fixed electrical contact, comprising plugs and lines for example, makes the air bag unit particularly safe during operation.  
      If the air bag unit has a retainer plate for arrangement of the air bag, which has an aperture for a free end of the support, the air bag unit can be fastened to the integrated support particularly simply, for example by pressing it on.  
      The assembly according to the disclosure may comprise a steering column switch unit with at least one steering column switch and a switch housing. The complexity of the assembly can be increased by integrating these components, thus facilitating final assembly of the motor vehicle.  
      The switch housing can also be designed to accommodate a circuit board and/or a clock spring. This is also described in the above-mentioned application “Vorrichtung für ein Lenksystem eines Kraftfahrzeugs” [Device for a Steering System for a Motor Vehicle].  
      The switch housing and/or the circuit board can be designed to accommodate stationary sensors of a torque sensor and/or of a rotation angle sensor.  
      The switch housing can be positioned on a component that is integrated on the vehicle body and at the same time be secured against twisting. This makes the installation of the switch housing particularly simple. The switch housing, however, can also be positioned by means of the rotor element and/or the steering wheel hub and/or the steering wheel, at least indirectly, and it can be secured against twisting on a component that is integrated on the vehicle body. This way, the switch housing can be positioned within tight tolerances relative to the rotor element and/or the steering wheel hub and/or the steering wheel, so that particularly the precise arrangement of coding elements of torque sensors and/or rotation angle sensors is facilitated. The component that is integrated on the vehicle body may be formed, for example, by the support and/or by a jacket tube surrounding the steering shaft.  
      The assembly may also include a drive, which drives the rotor element. Such a drive makes it possible, for example, to vary the resistance at which the steering wheel can be rotated, so that the driver of the motor vehicle can receive feedback about certain dynamic conditions of the motor vehicle. It is also possible that the drive performs or supports the motion of the steering wheel in a direction proposed by a driver assistance system.  
      The assembly can be used for a conventional steering system, wherein the motion of the steering wheel is transmitted mechanically to the motion of a steering shaft. The assembly can, however, also be provided for a steer-by-wire steering system.  
      The disclosure also relates to different methods for the installation of an assembly for a steering system of a motor vehicle.  
      Additional advantages, characteristics, and details of the present disclosure will be apparent from the description, in which with reference to the drawing a particularly preferred embodiment is described in detail. The characteristics illustrated in the drawing and mentioned in the claims as well as in the description can be essential for the disclosure either alone or in any random combination.  
      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. 
    
    
     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. The figures show:  
       FIG. 1 a  perspective view of an assembly according to the disclosure in a sub-assembly state;  
       FIG. 2 a  section of the assembly according to the disclosure in a complete installation state; and  
       FIGS. 3 and 4  detailed views of the assembly. 
    
    
     DETAILED DESCRIPTION  
      The following description is merely exemplary in nature and is not intended to limit the present disclosure, application, or uses.  
      In  FIG. 1 , an assembly according to the disclosure has been given the overall reference numeral  2 . It comprises a hollow cylindrical rotor element  4 . The rotor element  4  can be connected torque proof to an elastic element  6 , which will be explained in detail with reference to  FIG. 4 .  
      To the left of the elastic element  6 , the bottom part  8  and the top part  10  of a switch housing are illustrated. The top part  10  of the switch housing has a ring-shaped chamber  11  for a clock spring, which is not shown, facing away from the bottom part  8  of the switch housing. The switch housing serves, among other things, the accommodation of two steering column switches  12 . A circuit board  14 , which in turns serves for the arrangement of a rotational speed sensor  16 , can be inserted in the bottom part  8  of the switch housing  8  [sic]. The sensor  16  can be used to record the number of full steering wheel revolutions of a steering wheel  30 .  
      Inside the switch housing, a second coding element  18  may be provided, which is part of a torque sensor. Parallel to the second coding element  18 , a first coding element  20  can be provided, which is part of a rotation angle sensor. The coding elements  18  and  20  are associated with a light guide element  22 , the function of which will still be described with reference to  FIG. 2 .  
      The first coding element  20  is fastened to a retainer ring  24 , which is illustrated to the right of the top part  10  of the switch housing. A bearing ring  26  is provided for positioning the retainer ring  24  on the top part  10  of the switch housing.  
      The components  8  to  26  form an assembly group  28 , which can be slid onto the rotor element  4 . Accordingly, the steering wheel  30  can be placed on the rotor element  4 , where it is mounted rotatably about the rotor element  4  and can be secured in the axial direction by means of a circlip  32 . After placing the assembly group  28  on the rotor element  4 , a gearbox element  34  configured as a gear wheel can be placed on the rotor element  4  and connected torque proof thereto.  
      The assembly configured this way, which comprises all the parts  4  to  34  mentioned above, can be placed together with the rotor element  4  and with the help of two roller bearings  36  onto a support  38  that is integrated on the vehicle body. The support  38  has a base region  40  as well as a cylindrical section  42 . It is dimensioned such that the roller bearings  36  may be disposed thereon, so that the rotor element  4  is mounted rotatably on the section  42 .  
      The cylinder section  42  has such a length that a retainer plate  44  can be placed on the free end penetrating the steering wheel  30  and that it can be connected torque proof to the cylindrical section  42 . On the retainer plate  44 , an air bag  46  is provided, which just like the retainer plate  44  and the cylindrical section  42  as well as the support  38 , is not coupled for rotation with the steering wheel  30 , thus is fixed. A cover  48  covers the air bag  46 , which cover likewise does not rotate along with the steering wheel  30 , so that a monitor  50  provided on the cover  48  remains in the position illustrated in  FIG. 1  even when the steering wheel  30  turns.  
      Alternatively to the arrangement described above, the cover  48  may also not be connected to the retainer plate  44 , but instead to the steering wheel  30  (for example the ring-shaped base body  49  of the steering wheel  30 ). As a result, the cover  48  rotates jointly with the steering wheel. The cover  48  may be provided with operator elements such as switches, knurling wheels etc., which then rotate jointly with the cover  48 —in an ergonomically advantageous manner. The operator elements can be electrically contacted with the help of the above-mentioned clock spring.  
      The electric contact to the air bag  46  can be established with the help of an electrical contact  52 , which penetrates the hollow cylindrical section  42 .  
      The support  38  may be placed with its base region  40  on complementarily designed mounts on the integrated jacket tube  54 . The jacket tube  54  serves the mounting of a steering shaft  56 , which has a gear wheel  58  on its free end, which is configured for a combing engagement with the gearbox element  34 . The support  38  can be connected to the corresponding mounts of the jacket tube  54  with the help of two fastening elements  60 , which penetrate the base region  40  of the support.  
      So as to protect the components described above and illustrated in  FIG. 1  to the left of the steering wheel  30 , an upper steering column housing  62  and a lower steering column housing  64  are provided.  
      The assembly  2  is particularly easy to install. This is also due to the fact that essentially only two joining directions are required for installation. For one, this is the joining direction  66  extending coaxially to the steering axis of the steering wheel  30  and secondly the joining direction  68  extending perpendicularly thereto.  
       FIG. 2  illustrates a section of the mounted assembly  2 . It is apparent that the steering wheel  30  has a central steering wheel hub  70 , which can rotate in relation to the rotor element  4 . The steering wheel hub  70  comprises a total of three journal mounts  72 , which are also shown in  FIG. 3 . Journals  74 , which are configured as one piece with the retainer ring  24 , protrude into the journal mounts  72 . The retainer ring  24  comprises radially on the outside an annular collar  76 . The collar  76  slides into a bearing section  78 , which is configured on the top part  10  of the switch housing. Furthermore, the collar  76  is fixed in the axial direction with the help of a circlip  26 . As a result of the mount described above, the steering wheel  30  can rotate and the first coding element  20  connected to the retainer ring  24  can rotate via the journals  74  and the retainer ring  24 .  
      Adjacent to the first coding element  20 , the circuit board  14  is disposed inside the bottom part  8  of the switch housing. A light-emitting diode  80  is disposed thereon, which conducts light across the light guide element  22  back towards a photoreceiver  82 , which is likewise disposed on the circuit board  14 . Codings (which may be configured for example as segment-shaped apertures) of the first coding element  20  may penetrate through the free space formed between the light guide element  22  and the photoreceiver  82 , so that the photoreceiver  82  receives the corresponding light signals subject to the rotation angle position of the steering wheel  30 .  
      The second coding element  18  is disposed parallel to the first coding element  20 , the codings (which may be configured for example as segment-shaped apertures) of which second element may also produce or interrupt the light beam between the light guide element  22  and the photoreceiver  82 . The second coding element  18  is mounted on a retainer ring  84 , which is in turn connected torque proof to the rotor element  4 . The retainer ring  84  comprises radially outside a tooth system, which interacts with a corresponding tooth system of the rotational speed sensor  16 .  
      Upon rotation of the rotor element  4 , the gearbox element  34  rotates, which in turn drives the gear wheel  58 . The gear wheel is connected to the steering shaft  56  via a screw  86 .  
      The rotational motion of the steering wheel  30  is transmitted to the rotor element  4  by means of the elastic element  6 , which is also illustrated in  FIG. 4 . The elastic element  6  has a total of three elastic-bending sections  92 , which extend in the radial direction and are received without play in corresponding grooves  94 , which are configured in the steering wheel hub  70 . Upon rotation of the steering wheel  30 , the steering wheel hub  70  rotates, wherein the elastic-bending sections  92  of the elastic element  6  are driven via the grooves  94 . The rotor element  4  is driven by the torque proof connection to the elastic element  6 .  
      The elastic-bending sections  92  allow mutual angular offset of the steering wheel  30  and the rotor element  4  when correspondingly high torque is applied on the steering wheel  30 . So as to protect the elastic element from overloads, the rotor element  4  according to  FIG. 3  has a cam  90  on its outer circumference, which cam engages in a groove  88  formed in the steering wheel hub  70 . The groove  88  is dimensioned such that the cam  90  can rotate by +/−7° relative to the groove  88 .  
      The maximum angular offset of +/−7° is greater than the maximum angular offset that has to be measured; this one is +/−4°, for example.  
      The rotational motion of the steering wheel  30  can also be transmitted directly onto the rotor element  4 , i.e., without use of an elastic element  6 . For such an arrangement, and also for the described arrangement, the interposition of the gearbox elements  34  and  58  results in a reversal in the rotational direction between the steering wheel  30  and the steering shaft  56 . This reversal can again be reversed by a suitable configuration of the downstream steering gear, for example in that the steering shaft in the installation position combs from beneath with the gear rod of the steering gear