Abstract:
The invention relates to an apparatus for securing a wiper arm, which is driven via a lever mechanism ( 10 ) that has a drive lever, connected in a manner fixed against relative rotation to the drive shaft ( 12 ), and a steering lever ( 22, 24, 26 ) connected to an axle ( 16, 18, 20 ), which are pivotably connected to a wiper lever ( 112 ). 
     It is proposed that the steering lever ( 22, 24, 26 ) is braced in the mounting direction ( 28 ) on a bearing shoulder ( 30, 32, 34 ) on the axle ( 16, 18, 20 ).

Description:
BACKGROUND OF THE INVENTION 
   The invention is based on an apparatus for securing a wiper arm. 
   Wiper systems with a plurality of windshield wipers for motor vehicles are secured with their wiper bearings directly or indirectly via a mounting tube to the body of the motor vehicle. The mounting tube carries a wiper drive mechanism with a wiper motor, whose motor shaft, via a rod assembly, drives cranks that are solidly connected to one end of a drive shaft for each windshield wiper. 
   At least one radial bearing is provided in the bearing housing, and an axial bearing is provided on the face ends between the bearing housing and a part solidly connected to the drive shaft. The drive shaft protrudes from the vehicle body and moves a wiper arm, connected to it, with a wiper blade over a windshield. In order to adapt a wiping surface swept by the wiper blade favorably to a shape of the windshield, it is known to drive the wiper arm via a lever mechanism. As a rule, the lever mechanism has a drive lever secured to the drive shaft and a steering lever supported on an axle, and these levers are pivotably connected to a wiper lever connected to the wiper arm. 
   From German Patent Disclosure DE 44 28 371 A1, a shaft hub connection of a wiper is known, in which the drive shaft has a cross-sectional region that deviates from radial symmetry and also has a bearing shoulder. Placed between the drive shaft and the fastening part is a pressure piece, which has an opening that even before assembly is embodied to suit the cross-sectional region deviating from radial symmetry and which positively surrounds the drive shaft. The pressure piece also has an outer cone, with which it is pressed via a separable fastening element on the drive shaft into a suitably shaped inner cone of the fastening part. The fastening part is pressed onto the bearing shoulder by the fastening element via the pressure piece and fixed in the longitudinal direction of the shaft. 
   In the proposed embodiment, production variations have only slight influence on the precision of positioning of the wiper arm. The wiper arm can be secured with a high tightening moment, without influencing the positioning precision of the wiper arm. 
   SUMMARY OF THE INVENTION 
   According to the invention, the steering lever of a lever mechanism is braced in the mounting direction on a bearing shoulder on the axle. The steering lever is supported in the axial direction at a defined point. Production variations of the steering lever and the axle have only a slight effect on the position of the steering lever relative to the axle. Without affecting the precision of positioning, the steering lever can be secured by a fastening element with a high axial force on the bearing shoulder. By means of a precise position of the steering lever on the axle, stresses and wear in the lever mechanism can be reduced. Especially advantageously, not only the steering lever but also the drive lever is braced in the mounting direction on a bearing shoulder on the drive shaft. The drive lever and the steering lever can be secured on the drive shaft and the axle in the axial direction at precise positions adapted to one another. Undesired differences in height between the drive lever and the steering lever and stresses can be avoided. 
   The steering lever can be braced directly on the bearing shoulder, or advantageously via a disk. With a disk, the diameter of the axle can be made smaller, and thus the axle can be more economical. The steering lever can also advantageously be supported on a large area, which reduces the load on the steering lever from a tilting moment. Braced on the disk at the bearing point with the axle, the steering lever can be made thinner, lighter in weight, and less expensive. 
   The windshield wiper system with the drive shafts and the axles is as a rule furnished separately from the lever mechanism and the wiper arm to an auto manufacturer. In one feature it is proposed that the disk be pressed nonpositively onto the axle, for instance by a press fit, a conically extending axle, and/or a chamfer. The disk is connected in captive fashion to the windshield wiper system and need not be shipped separately. Furthermore, the disk can be positioned and oriented accordingly in the manufacture of the wiper system. As a result, the steering lever can be mounted quickly and exactly on the disk by the vehicle manufacturer. 
   To obtain an unambiguous bearing point, the steering lever is connected to a pivotable axle in a manner fixed against relative rotation. As a rule, the steering lever is secured to the axle with a nut. The steering lever and the axle should therefore already be connected in a manner fixed against relative rotation upon assembly, to prevent joint rotation of the axle during assembly. The effect of torque between the axle and the steering lever is created on the one hand by the friction of the axle in its bearing point and on the other by the tightening and loosening of the nut and is less than the drive moment. Advantageously, the connection, fixed against relative rotation, between the axle and the steering lever is designed for the low torque to be transmitted and as a result can be made smaller, lighter in weight, and less expensive. This is attained with an embodiment according to the invention in which a rotationally fixed connection between the steering lever and the axle is established via the disk. An effective tilting moment can be supported via the disk, and the low effective torque can be transmitted via a short axial connection, thus economizing in terms of both axial structural length and weight. 
   Advantageously, a nonpositive engagement is utilized between the axle and the disk, and a positive engagement is utilized between the disk and the steering lever. The shaft can be embodied rotationally symmetrically and economically, and the disk is secured in captive fashion. With a positive engagement between the disk and the steering lever, the steering lever is already fixed in a manner fixed against relative rotation even once it is placed on the disk and can be mounted in a simple way. By its contact with the disk, the steering lever is unambiguously defined in terms of its position. To avoid an overdefined bearing of the steering lever, the disk and the steering lever are connected in the pivoting direction via a clearance fit. 
   A structurally simple, space-saving positive engagement is attained with side walls of the steering lever that positively surround the disk in the pivoting direction, specifically with a cross-sectional region deviating from radial symmetry, for instance with one or more flat faces on the steering lever and on the disk. Furthermore, the force to be transmitted is advantageously introduced from the steering lever to the disk over a large radius, so that only small forces act on the steering lever. 
   To facilitate mounting the side walls on the disk, it is proposed that the side walls be embodied as merging in the mounting direction, with a smaller cross-sectional region deviating from radial symmetry, to a larger, preferably round cross-sectional region. The steering lever can advantageously, in a first mounting step, be positioned with the larger, round cross-sectional region on the disk, and in a second mounting step, by rotation of the steering lever or of the disk with the axle, it can be made to rest with the cross-sectional region deviating from radial symmetry above the disk, so that the side walls and the disk can mesh with one another positively in the pivoting direction. This makes simple, fast assembly of the steering lever possible. 
   Besides the connections proposed, the steering lever and the disk, and the disk and the axle, can each be connected with one another in the pivoting direction nonpositively and/or positively. Especially a purely positive connection in the pivoting direction between the disk and the axle can be advantageous, if after the windshield wiper system has been mounted on a vehicle body a component, such as a scuttle cover, has to be mounted on the axle behind the disk in terms of the mounting direction. Without a premounted disk, the component can simply be mounted on the axle with a small opening and possibly sealed off. Next, the disk can be mounted in the pivoting direction positively, with or without a slight nonpositive engagement. 
   In one feature, instead of being connected via the disk, the steering lever is connected directly to the axle in a manner fixed against relative rotation, and specifically the axle advantageously has a cross-sectional region deviating from radial symmetry, which is for instance polygonal, elliptical, etc., and which positively surrounds the steering lever. A connection between the side walls of the steering lever and the disk can be dispensed with, and the disk can be smaller or even omitted. Furthermore, premounting of the disk and a captive securing means can be dispensed with, making it possible not to mount the disk alone but instead to mount it along with the lever mechanism, for instance after a scuttle cover has been installed. The positive engagement in the pivoting direction between the steering lever and the axle can be attained by means of one or more flat faces on the axle or by means of an elliptical cross-sectional area of the axle and a correspondingly embodied opening in the steering lever. 
   In one feature of the invention, the drive shaft has a cross-sectional region deviating from radial symmetry. Placed between the drive shaft and the drive lever is a pressure piece, which has an opening corresponding to the cross-sectional region deviating from radial symmetry and positively surrounds the drive shaft in the pivoting direction. The pressure piece is pressed by a separable fastening element, such as a nut, with an outer cone into an inner cone of the drive lever and fixed with the drive lever on the bearing shoulder. The drive lever is positioned exactly on the bearing shoulder in the axial direction. The pressure piece is connected in the pivoting direction to the drive shaft via a positive engagement, preferably via from one to twelve large, load-bearing faces, for instance via a hexagon or an elliptical cross-sectional area, and as a result can easily be pulled off together with the drive lever from the drive shaft, or dismantled. To support the pressure piece and in particular the drive lever on the drive shaft without play, in one feature the cross-sectional region of the drive shaft, deviating from the radial symmetry, is embodied at least in one region in the mounting direction with an increasing diameter, onto which the pressure piece can be fixed without play by nonpositive engagement. When the pressure piece is slipped on, a larger inside diameter of the pressure piece also first meets a smaller outside diameter of the drive shaft, making it easy to install the pressure piece. 
   If the steering lever, like the drive lever, is connected to the axle via a pressure piece, then this lever is positioned exactly in the axial direction on the axle and can easily be pulled from the axle along with the pressure piece. Furthermore, with the same kind of securing of the drive lever on the drive shaft and of the steering lever on the axle, the number of different components and production costs are reduced. 
   Only a low torque acts between the steering lever and the axle, and thus the steering lever can advantageously be embodied as a sheet-metal part. Especially in the case of the rotationally fixed connection of the steering lever and the axle via the disk, the torque is transmitted over a large radius by a positive engagement, and the tilting moment on the disk is supported via a large area, each of which contributes to a lesser load on the steering lever and argues for the embodiment of the steering lever as a sheet-metal part. Also in the embodiments according to the invention, a cone that widens in the mounting direction can be avoided, and the steering lever can advantageously be manufactured from one side and one or more deep drawing operations. With a steering lever embodied as a sheet-metal part, economies of weight, production effort, and expense can be achieved. 
   To increase the rigidity of the steering lever in the region of the connection point to the axle, the steering lever in one feature has a cup-shaped indentation in this region in a cap side. 

   
     BRIEF DESCRIPTION OF THE DRAWING 
     Further advantages will become apparent from the following drawing description. Exemplary embodiments of the invention are shown in the drawing. The drawing, description and claims include numerous characteristics in combination. One skilled in the art will expediently consider the characteristics individually as well and put them together to make useful further combinations. 
     Shown are: 
       FIG. 1 , a detail of a windshield wiper system with a lever mechanism; 
       FIG. 2 , a section taken along the plane II in  FIG. 1 ; 
       FIG. 3 , an exploded view of a detail III in  FIG. 2 ; 
       FIG. 4 , a steering lever seen from below; 
       FIG. 5 , a variant of  FIG. 3 ; 
       FIG. 6 , an axle of  FIG. 5  from above; 
       FIG. 7 , an apparatus of  FIG. 5  in the installed state; 
       FIG. 8 , a variant of  FIG. 2 ; 
       FIG. 9 , an axle from above; 
       FIG. 10 , a pressure piece from above; and 
       FIG. 11 , a disk from above. 
   

   DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     FIG. 1  shows a detail of a wiper system for a motor vehicle, whose wiper bearings  106 ,  108  are secured via a mounting tube  104  to a body of the motor vehicle. The mounting tube  104  carries a wiper drive mechanism, not identified by reference numeral, which via a rod assembly  110  drives a drive shaft  12 . The drive shaft  12  is radially and axially supported in the wiper bearing  108 , protrudes from the body, and moves a drive lever  14 , secured to its free end, of a lever mechanism  10 . Besides the drive lever  14 , the lever mechanism  10  has a steering lever  22 , which is supported in the wiper bearing  106  via a pivotable axle  16 , and a wiper lever  112 , which is pivotably connected to the drive lever  14  and the steering lever  22  via two bearings  114  and  116 . The wiper lever  112  moves a wiper arm, secured to it and not shown in further detail, with a wiper blade over a windshield. 
   Accordingly to the invention, the steering lever  22  and preferably the drive lever  14  are braced in the mounting direction  28  via a disk  36 ,  118  on a bearing shoulder  30 ,  68  on the axle  16  and the drive shaft  12 , respectively (FIG.  2 ). The drive lever  14  and the steering lever  22  can be secured on the drive shaft  12  and axle  16 , respectively, in the axial direction at precise positions adapted to one another. Undesired differences in height between the drive lever  14  and the steering lever  22  and stresses in the wiper bearings  106 ,  108  and the bearings  114 ,  116 , and resultant wear, can be avoided. 
   The disk  36  is pressed in captive fashion nonpositively onto the rotationally symmetrical axle  16  and is solidly connected to the axle  16  in the pivoting direction  42 ,  44 . The steering lever  22 , embodied as a sheet-metal part, is connected positively to the axle  16  in the pivoting direction  42 ,  44  via a clearance fit  120  via the disk  36 , specifically with side walls  46 ,  48  that positively surround the disk  36  (FIGS.  2  and  3 ). To make assembly simpler, the side walls  46 ,  48  are embodied as merging in the mounting direction  28  from a smaller cross-sectional region  50  deviating from radial symmetry to a larger cross-sectional region  52  (FIG.  4 ). The steering lever  22  can advantageously be positioned in a first mounting step with the larger, round cross-sectional region  52  on the disk  36 , and in a second mounting step, by rotation of the steering lever  22  or the disk  36  with the axle  16 , it can be made to rest with the cross- sectional region  50  deviating from radial symmetry above the disk  36 , so that the side walls  46 ,  48  and the disk  36  can mesh with one another positively in the pivoting direction  42 ,  44 . The cross-sectional region  50  deviating from radial symmetry has flat faces  122 , on which flat faces  124  of the disk  36  come to rest with positive engagement. The steering lever  22  is fixed in the axial direction on the bearing shoulder  30  by a nut  64  via the disk  36 . By the positive engagement of the steering lever  22  with the axle  16  via the disk  36 , the nut  64  can be tightened and loosened without causing the axle  16  to rotate with it. This makes fast, simple mounting and unmounting of the steering lever  22  possible. 
   In  FIGS. 5 ,  6  and  7 , instead of being connected via a disk  40 , a steering lever  26  is connected in rotationally fixed fashion directly to an axle  20  below a thread  136 , and specifically, the axle  20  has a cross-sectional region  54 , deviating from radial symmetry, that positively surrounds the steering lever  26  in the pivoting direction  42 ,  44  with a suitably opening  126 . The cross-sectional region  54 , deviating from radial symmetry, of the axle  20  has a flat face  128 , on which a flat face  130  of the opening  126  comes to rest. In the mounting process, first a scuttle cover  132  can be mounted with a seal  134  and then the disk  40  can be mounted, by way of which the steering lever  26  is braced on a bearing shoulder  34 . Preassembly of the disk  40  can be dispensed with, and in comparison to the disk  36  in the exemplary embodiment of  FIG. 3 , the disk  40  can be made smaller. Like the steering lever  22 , the steering lever  26  is fixed in the axial direction on the axle  20  with a nut  64 . 
   To increase the rigidity of the steering levers  22 ,  26 , embodied as sheet-metal parts, in the region of the connection point to the axle  16 , the steering levers  22 ,  26  have a cup-shaped indentation  100 ,  102  ( FIGS. 2 ,  3 ,  4 ,  5  and  7 ) in a cap side  96 ,  98 . 
   To reduce the number of different components, in the exemplary embodiment of  FIG. 8  a connection of a steering lever  24  to an axle  18  is embodied like the connection of the drive lever  14  to the drive shaft  12 . The drive shaft  12  and the axle  18  have a cross-sectional region  56 ,  70  ( FIGS. 2 ,  8  and  9 ) that deviates from radial symmetry. Between the drive shaft  12  and the drive lever  14 , and between the steering lever  24  and the axle  18 , a respective pressure piece  58 ,  72  is placed, which has an opening  60 ,  74  ( FIGS. 8 and 10 ) corresponding to the cross-sectional region  56 ,  70  deviating from radial symmetry and positively surrounds the drive shaft  12  and axle  18 , respectively, in the pivoting direction  42 ,  44 . The pressure piece  58 ,  72  is pressed by a nut  64  with an outer cone  62 ,  76  into an inner cone  66 ,  78  of the drive lever  14  and steering lever  24 , respectively, and fixed thereby via a disk  38 ,  118  on a bearing shoulder  32 ,  68  (FIGS.  8  and  9 ). The disk  38 ,  118  has an opening  138 ,  140 , embodied to suit the cross-sectional region  56 ,  70  deviating from radial symmetry, and these disks are pressed in captive fashion onto the axle  18  and the drive shaft  12 , respectively. The pressure piece  58 ,  72  is connected in the pivoting direction  42 ,  44  to the drive shaft  12  and axle  18  via a positive engagement, specifically via six large, load-bearing faces  84 ,  86 ,  88 ,  90 ,  92 ,  94  of a hexagon ( FIG. 9 ) and as a result can easily be pulled off or dismantled together with the lever  14 ,  24  from the drive shaft  12  and axle  18 . In order to support the pressure piece  58 ,  72  and in particular the drive lever  14  and the steering lever  24  without play, the cross-sectional region  56 ,  70  deviating from radial symmetry is embodied with an increasing diameter  80 ,  82  in the mounting direction  28 , onto which diameter the pressure piece  58 ,  72  can be fixed nonpositively without play.