Abstract:
The invention relates to a window wiper device ( 1 ) for motor vehicles, in particular for rear windscreen wipers with a wiper motor which is inserted into a housing base body ( 20 ), and a pole housing ( 10 ). The pole housing ( 10 ) is embodied free of seams over a portion of the circumference.

Description:
BACKGROUND AND SUMMARY OF THE INVENTION 
       [0001]    The present invention relates to a windshield wiper device for motor vehicles, in particular for rear windshield wipers comprising a wiper motor which is inserted into a housing base body, and a pole housing in which an armature is rotatably mounted. 
         [0002]    Such windshield wiper devices are, for example, known from U.S. Pat. No. 4,920,289, DE 32 20 131 A1, DE 32 35 622 A1, DE 41 16 100 A1 as well as DE 39 30 144 C2. 
         [0003]    In these known windshield wiper devices, a spherical bearing made of a sintered metal is used for mounting the armature shaft in the pole housing, and which is fixed at the base in a recess in the pole housing by a spring washer. The spring washer is adapted to the bearing. Owing to the rotatability of the spherical cap, the running characteristics of the wiper motor are not disadvantageously affected even with a slightly oblique position of the armature. 
         [0004]    A drawback with such a windshield wiper device is, however, the very complicated and thus costly mounting of the spherical bearing. 
         [0005]    The document EP-A-485001 discloses a method in which a roller bearing of an electric motor is inserted into a recess in the housing and is held by a projection formed in the recess. The manufacture of this projection as well as the recess is also complicated and costly. 
         [0006]    The object of the invention, therefore, is to provide a windshield wiper device, in particular for rear windshield wipers of a motor vehicle, which provides a manufacture and mounting of the armature shaft in the pole housing which is as simple as possible. 
         [0007]    This object is achieved according to the invention in that the pole tube is configured integrally and seamlessly over the circumference. 
         [0008]    In other words, the pole housing is not formed conventionally as in the prior art from rolled sheet steel or as a deep-drawn part but is produced from a standard material in one piece, which is widely available, and for example simply deflected. 
         [0009]    The use of a one-piece enclosed tubular material is also to be preferred due to its high mechanical rigidity and improved oscillatory and acoustic properties. Moreover, different lengths of pole housings may be produced in a simple manner, in which the adjustment to the desired length to be cut off may be altered on the machine by a single input into the computer. 
         [0010]    Due to the simplicity of the selected manufacturing material, it is associated with very little cost to provide the pole housing with anti-corrosive surfaces. Due to the simple manufacturing process and the only slight loading of the outer surface of the pole housing, the material loading as a result of treating the tubular cover does not have to be taken into account. 
         [0011]    The pole housing may consist of steel, a ceramic material or sintered metal. 
         [0012]    One advantageous embodiment of the invention accordingly provides to form the pole housing from a tubular portion deflected from a process endless tube produced in a continuous process. This tubular portion may be produced from widely available raw material, such as for example a steel tube, which as a steel material is cut to length. 
         [0013]    In an alternative embodiment, the pole housing is formed by a bushing produced by gravity die casting. 
         [0014]    For fastening to the bearing arrangement of the armature shaft arranged in the pole housing, a mounting element may be fastened to the pole housing. An opening, for example, may be provided in the mounting element which serves as a bearing. 
         [0015]    The diameter of the opening in the mounting element may be adapted to the dimensions of the bearing arrangement of the armature shaft depending on the application, so that each cylindrical bearing may be inserted into the mounting element irrespective of the external diameter thereof and thus may be used in the pole housing. This allows a particularly flexible assembly according to the type of loading and strength of the armature shaft. 
         [0016]    The mounting element may be either positioned or screwed on the pole housing in the form of a cap or inserted into the pole housing and fixed therein. This may, for example, be achieved by forming an interference fit between the pole housing and the mounting element. 
         [0017]    By the choice of the individual components, the mounting may be selected to be very flexible in particular the sequence of the mounting. With regard to further advantageous embodiments and developments of the invention, reference is made to the sub-claims and the following description of the drawings. 
       BRIEF DESCRIPTION OF THE DRAWING  
    
    
     DETAILED DESCRIPTION  
       [0018]    An electrical drive unit shown in the figure of a windshield wiper device for motor vehicles according to the invention comprises a substantially cup-shaped pole housing  10  which is integrally and seamlessly configured over the circumference. The pole housing  10  is formed from a tubular portion deflected from an endless tube produced in a continuous process and is provided at its outer surface  11  with an anti-corrosive layer  12 . An electrical armature  13  known per se is inserted in the pole housing  10 . At the front face, on the pole housing  10  a similarly substantially cup-shaped gear housing  20  is fastened, in which a transmission gear wheel  21  is received, which engages in a worm  23  connected to an armature shaft  22  of the armature  2 . The armature shaft  22  is mounted in the gear housing  20  in a spherical bearing  24 , which is axially secured by a retaining clip  25  in the gear housing  20 . 
         [0019]    The armature shaft  22  on its side remote from the gear housing  20  is mounted in the pole housing  10  by means of a cylindrical bearing  26  mounted by an interference fit. The cylindrical bearing  26  consists of a sintered metal. The toroidal and/or annular body of the cylindrical bearing  26  forms a lubricant storage. 
         [0020]    As a result of the large external diameter of the cylindrical bearing  26  which is substantially greater than a length L, when mounting the cylindrical bearing  26  by an interference fit, the internal diameter d i  corresponding to the external diameter of the armature shaft  22  is prevented from being reduced in diameter. Moreover, the mounting of the armature shaft  22  is thereby simplified. 
         [0021]    The large external diameter d a  of the pressed-in cylindrical bearing  26 , also allows in particular a sufficient pole volume for the lubricant and thus ensures efficient lubrication of the cylindrical bearing  26  over a long period. Due to the shorter length L of the cylindrical bearing  26 , the possible oblique positions of the armature shaft  22  do not act disadvantageously on the running of the drive unit, as due to the shortness of the cylindrical bearing  26  in practice it may not lead to distortion of the armature shaft  22  in the cylindrical bearing  26 . 
         [0022]    Additional securing elements, not shown, may be provided for fixing the cylindrical bearing  26  in its position within the pole housing  1 , such as for example spring washers or clamping rings. 
         [0023]    The cylindrical bearing  26  may be clamped in a mounting element  27  which is also of cylindrical configuration in order to be able to design the external diameter of the cylindrical bearing  26  to be variable and thus also to be able to adapt the lubricating properties to the respective conditions of use and thus to keep material costs as low as possible. Each cylindrical bearing  26  may be inserted via the mounting element  27  irrespective of the external diameter d a  thereof. Additionally, the mounting element  27  may either be positioned or screwed as a type of cap onto the pole housing  10  or inserted into the pole housing  10  and fixed therein, for example by forming an interference fit between the pole housing  10  and the mounting element  27 . The mounting element  27  may be fastened to the cylindrical bearing  26  preassembled on the pole housing. It is, however, also possible to preassemble the cylindrical bearing  26  initially on the armature shaft  22 , and subsequently to insert into the mounting element  27 , or even directly mount each individual component.