Abstract:
The invention relates to a windscreen wiper drive arrangement ( 1 ) having a drive shaft ( 4 ), extending out of a gear mechanism housing ( 3 ), for a windscreen wiper, in which the drive shaft ( 4 ) is guided axially through a protective sleeve ( 15 ) which is sealed with respect to the drive shaft ( 4 ) by means of at least one inner sealing element ( 18 ) and with respect to a vehicle component ( 11 ) by means of at least one outer sealing element. The invention provides for the protective sleeve ( 15 ) to be secured to the gear mechanism housing in order to protect said protective sleeve against axial movement in the direction of the vehicle component ( 11 ) and/or against rotational movement relative to the gear mechanism housing ( 3 ) by frictional engagement and/or by means of at least one separate securing element ( 25 ).

Description:
BACKGROUND OF THE INVENTION 
     The invention relates to a windscreen wiper drive arrangement. 
     A windscreen wiper drive arrangement is known from DE 299 01 686 U1 comprising a drive motor which is connected via an output shaft to a gear mechanism arranged in a gear mechanism housing. Guided out of the gear mechanism housing is a drive shaft for a windscreen wiper which is driven in an oscillating manner. Conventionally, the drive shaft is guided through an opening in the bodywork or a window, generally the rear window. To avoid water ingress, conventionally a protective sleeve is provided through which the drive shaft is guided in the axial direction. Said protective sleeve is sealed relative to the drive shaft by means of an internal sealing element, for example an O-ring, so that no water is able to run toward the interior along the drive shaft. Moreover, the protective sleeve is sealed by means of an external sealing element, in particular a so-called grommet, relative to the vehicle component through which the drive shaft is guided. It is known to press the protective sleeve provided with an internal cone onto an external cone of the gear mechanism housing, in particular a fixing dome, in the axial direction and thus to produce a non-positive connection between the gear mechanism housing and the protective sleeve. 
     Such a fastening of the protective sleeve has proved advantageous. As a result of external influences, in particular as a result of continuous shaking movements during travel or during repair work, however, the frictional connection between the protective sleeve and the gear mechanism housing may be released, which may result in the protective sleeve being able to move in the axial direction and/or in the peripheral direction. As a result, firstly there is the risk that the protective sleeve during operation of the windscreen wiper moves in an oscillating manner together with the drive shaft, which leads to greater wear of the internal sealing element. Moreover, the protective sleeve may become skewed such that an effective seal relative to the drive shaft and/or relative to the vehicle component, through which the drive shaft is guided, is no longer ensured. It leads to water ingress, in particular into the gear mechanism and/or motor housing and thus to increased occurrence of wear and an electrical short circuit. 
     SUMMARY OF THE INVENTION 
     The object of the invention is to provide an improved wiper drive arrangement in which the risk of failure of the seal is minimized. 
     The idea underlying the invention, additionally or alternatively to pressing the protective sleeve onto a gear mechanism housing portion, i.e. an exclusively non-positive and/or frictional connection, is to provide a positive connection between the protective sleeve and the gear mechanism housing and/or a separate fixing element for fixing the protective sleeve to the gear mechanism housing, in order to avoid a relative axial movement of the protective sleeve in relation to the gear mechanism housing in the direction of the vehicle component and/or in the peripheral direction. By the additional or alternative securing means for the frictional connection, increased wear of the seal, in particular between the protective sleeve and drive shaft, may advantageously be avoided, as the protective sleeve always maintains a precisely defined position relative to the sealing elements and the drive shaft. An inadvertent release of the protective sleeve from said defined relative position is advantageously avoided. Due to the provision of a positive connection and/or a separate fixing element, substantially greater moments may be absorbed and/or cushioned by the protective sleeve. 
     In principle, various possibilities exist for ensuring an additional or alternative securing and/or fixing of the protective sleeve to the gear mechanism housing. 
     According to an advantageous embodiment of the invention, the protective sleeve and a portion of the gear mechanism housing, preferably a fixing dome of the gear mechanism housing, engage in a mutually interlocking manner. As a result of this positive connection, a rotation of the protective sleeve relative to the gear mechanism housing is avoided. In addition to this securing against a movement in the peripheral direction, the protective sleeve may be secured against an axial movement. To this end, the axial fixing may, for example, be produced by a further positive connection of the protective sleeve with the gear mechanism housing. A support of the protective sleeve in the axial direction on a component supported on the drive shaft, in particular a speed nut, or a radial portion configured integrally with the drive shaft is also conceivable. 
     Additionally or alternatively, in a development of the invention it is provided to latch the protective sleeve to the gear mechanism housing. In this connection, the at least one latching mechanism may be configured such that it secures the protective sleeve exclusively against a relative axial movement or exclusively against a rotational movement relative to the gear mechanism housing. Preferably, however, the protective sleeve is latched to the gear mechanism housing such that both degrees of freedom are eliminated. 
     According to a preferred embodiment, it is provided that the latching means are arranged for fixing the protective sleeve to the gear mechanism housing on a latching arm of the protective sleeve facing in the direction of the gear mechanism housing. For example, the latching arm, preferably at its free end, comprises a recess which engages in a latching lug of the gear mechanism housing. It is also conceivable to transpose the latching lug and the recess. 
     A particularly secure and fixed connection between the protective sleeve and the gear mechanism housing is maintained when the protective sleeve is calked to the gear mechanism housing. To this end, the protective sleeve preferably comprises at least one opening through which an extension of the gear mechanism housing, generally consisting of cast aluminium, projects. After positioning the protective sleeve, the extension, in particular by the effect of impact, is widened at its free end such that the protective sleeve may no longer be pulled off the extension. As a result of the calking, the protective sleeve is secured both in the axial and in the peripheral direction. 
     Additionally or alternatively, it is advantageous to rivet the protective sleeve to the gear mechanism housing by means of individual rivets. 
     In a development of the invention, it is advantageously provided to secure the protective sleeve on the gear mechanism housing by means of a double-locking speed nut. A double-locking speed nut comprises resilient elements both on its internal periphery and on its external periphery, which is under tension with and/or bites into the gear mechanism housing, in particular the fixing dome, on the one hand, and, on the other hand, the protective sleeve. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Further advantages and expedient embodiments may be derived from the further claims, the description of the figures and the drawings, in which: 
         FIG. 1  shows a sectional view of a windscreen wiper arrangement comprising a protective sleeve, which is positively connected to a gear mechanism housing by means of interlocking, 
         FIG. 2  shows a sectional view of the protective sleeve along the cutting line A-A according to  FIG. 1 , 
         FIG. 3  shows an enlarged detail of  FIG. 2 , 
         FIG. 4  shows a sectional view of the protective sleeve along the cutting line B-B according to  FIG. 2 , 
         FIG. 5  shows a side view of the fixing dome of the gear mechanism housing, 
         FIG. 6  shows a sectional view of the fixing dome, with the drive shaft located on the inside, along the cutting line C-C according to  FIG. 5 , 
         FIG. 7  shows an enlarged detail of  FIG. 6 , 
         FIG. 8  shows a sectional view of a windscreen wiper drive arrangement, in which the protective sleeve is calked to the gear mechanism housing, 
         FIG. 9  shows a sectional view of the protective sleeve along the cutting line D-D according to  FIG. 8 , 
         FIG. 10  shows a windscreen wiper drive arrangement, in which the protective sleeve is fixed to the fixing dome of the gear mechanism housing by means of a double-locking speed nut, 
         FIG. 11  shows a view of the speed nut fixed to the protective sleeve, 
         FIG. 12  shows an enlarged detail of  FIG. 10 , 
         FIG. 13  shows a windscreen wiper arrangement, in which the protective sleeve is positively connected to the gear mechanism housing and is additionally secured in the axial direction by means of a speed nut, 
         FIG. 14  shows a view of the speed nut, 
         FIG. 15  shows a windscreen wiper drive arrangement in which the protective sleeve  15  is latched to the gear mechanism housing  3 , and 
         FIG. 16  shows a view of a latching arm rotated by 90° relative to  FIG. 15 . 
     
    
    
     DETAILED DESCRIPTION 
     The same components and components with the same function are identified in the figures by the reference numerals. 
     In  FIG. 1  a windscreen wiper drive arrangement  1  is shown for a motor vehicle. An electric drive motor, not shown, is connected to a gear mechanism  2  via an output shaft, also not shown. The partially shown gear mechanism  2  is arranged inside a partially shown gear mechanism housing  3  made of aluminum. By means of the motor and the gear mechanism  2 , a drive shaft  4  is driven in an oscillating manner. A wiper arm may be fixed to the free end  5  of the drive shaft  4  guided out of the gear mechanism housing  3 . On the drive shaft  4  is located a gear wheel  7  which meshes with a toothed element of the gear mechanism  2 . The drive shaft  4  is mounted by means of two spaced-apart bearings  8 ,  9  inside the gear mechanism housing  3  in the axial direction as well as in the radial direction. The front bearing  8  is located in a fixing dome  10  of the gear mechanism housing  3  which surrounds the drive shaft  4  over part of its longitudinal extension in the peripheral direction. 
     The drive shaft  4  is passed out of the gear mechanism housing  3  and/or the fixing dome  10  and at a distance thereto through a vehicle component  11 , in particular a bodywork panel or a window pane. To this end, an opening  12  is provided in the vehicle component  11 . 
     So that from the outside  13  of the vehicle no water is able to penetrate in the direction of the gear mechanism  2 , a protective sleeve  15  is provided with circular internal and external cross-sectional surfaces. The protective sleeve is pressed with its conically widened end region  16  onto the conically tapered fixing dome  10  in the axial direction in the direction of the vehicle component  11 . In a groove  17  on the internal periphery of the protective sleeve  15  an internal sealing element  18 , configured as an O-ring, is arranged. Said O-ring bears against the entire periphery of the drive shaft  4  and prevents penetration of water from the outside  13  into the interior of the protective sleeve  15 . With an oscillating movement of the drive shaft  4 , said drive shaft slides along the internal periphery of the internal sealing element  18 . In order to prevent water ingress between the external periphery of the protective sleeve  15  and the opening edge of the opening  12  in the direction of the gear mechanism housing  3 , an external sealing element  19  is provided inside the opening  12 , in particular a grommet held on the peripheral edge of the opening  12 . Said sealing element bears sealingly against the external periphery of the protective sleeve  15 . 
     Should the frictional connection between the fixing dome  10  and the internal periphery of the protective sleeve  15  be released, rotation of the protective sleeve  15  in the peripheral direction is avoided by the positive connection between the protective sleeve  15  and the fixing dome  10 . 
     The positive connection between the protective sleeve  15  and the fixing dome  10  is shown in detail in  FIG. 2  to  FIG. 7 . As is revealed from  FIG. 2 , inwardly facing teeth  20  with a triangular cross section (see  FIG. 3 ) are provided on the internal periphery extending in the axial direction and radially spaced apart in the peripheral direction. Said teeth engage in recesses, not shown, on the external periphery of the fixing dome  10 . 
     Additionally or alternatively, radially outward facing teeth  21  which extend in the axial direction and are spaced apart on the external periphery of the fixing dome  10  in the peripheral direction, are provided and engage in recesses of complementary shape, not shown, on the internal periphery of the protective sleeve  15 . As a result of the interlocking of the protective sleeve  15  with the fixing dome  10 , a relative rotational movement between the protective sleeve  15  and the gear mechanism housing  10  is advantageously avoided. The pressing-on merely has the function of securing the protective sleeve  15  against axial displacement. If the pressing-on is eased, the protective sleeve may not rotate but may be axially displaced in the direction of the vehicle component  11 . If required, the pressing-on may be entirely dispensed with, in particular when an axial displacement movement is prevented by a positive connection or a separate fixing element. 
     It is also conceivable that the two sets of teeth  20 ,  21  shown in  FIGS. 2 and 6  interlock. In this case, the teeth  20 ,  21  are supported against one another in the peripheral direction. As clearances are formed, with such a positive connection which is not configured to be complementary in shape in the axial direction, it is possible, however, that water which has penetrated is able to run down through said clearances in the direction of the outside of the gear mechanism housing  3 . 
     In  FIGS. 8 and 9 , an alternative embodiment is shown. The protective sleeve  15  which is only shown partially is pushed onto the fixing dome  10  of the gear mechanism housing  3 , but not pressed-on. The securing against an axial movement as well as a rotational movement of the protective sleeve  15  is implemented by calking the components ( 15 ,  10 ). To this end, two bearing portions  22  and/or bearing tabs are provided on the protective sleeve  15  encompassing the drive shaft  4 , which are opposed in the axial direction, arranged slightly offset relative to one another and extend in the transverse direction relative to the axial extension of the protective sleeve  15 . Each bearing portion  22  comprises an opening  23  through which one respective extension  24  is guided and which is configured integrally with the gear mechanism housing  3  made of cast aluminum. In the respective right-hand half of the drawing of  FIGS. 8 and 9 , the extension  24  already calked by pressing is shown. The free end of the extension  24  is thus widened, such that it may no longer be passed through the opening  23 . In the left-hand half of the drawing the calking step has not yet been carried out. The, as yet, unaltered extension  24  passed through the opening  23  may be identified. The extensions  24  prevent a rotation of the protective sleeve  15 . The securing in the axial direction is ensured by the widened heads of the extensions  24 . 
     In the embodiment shown in  FIG. 10 , the protective sleeve  15  is also slipped over the fixing dome  10  of the gear mechanism housing  3 . Optionally, the protective sleeve made of plastics may be pressed onto the fixing dome  10 . For securing against an axial movement of the protective sleeve as well as rotation of the protective sleeve  15 , the protective sleeve  15  is connected to the gear mechanism housing  3  by means of the fixing element  25  shown in detail in  FIG. 11  and configured as a double-locking speed nut. The double-locking speed nut  25  comprises resilient, spaced-apart, radially outwardly facing tabs  26  on the external periphery in the peripheral direction, and on its internal periphery radially inwardly facing tabs  27 . By means of the outer tabs  26 , the double-locking speed nut  25  bites into the internal periphery of a lower projection of the protective sleeve  15 . By means of its inner tabs  27 , the double-locking speed nut bites into the external periphery of the fixing dome  10 . This may be seen in detail in  FIG. 12 . The inner tabs  27  are axially bent upwards in the direction of the free end of the fixing dome  10 , in contrast to which the outer tabs  26  are bent back in the opposing direction. For example, the double-locking speed nut  25  is initially under tension inside the projection  28  of the protective sleeve  15 , whereupon the unit made up of the protective sleeve  15  and the double-locking speed nut  25  is pushed thereon from the free end of the fixing dome  10 . 
     In the embodiment according to  FIG. 13 , an additional securing element  29  is provided in addition to the interlocking between the protective sleeve  15  and the fixing dome  10 . Said securing element is configured as a speed nut (see  FIG. 14 ). The speed nut  29  comprises on the internal periphery resilient tabs  27  and/or claws with which it bites into the smooth drive shaft  4 . After mounting the protective sleeve  15  on the fixing dome  10 , the securing element  29  is pushed from the free end  5  of the smooth drive shaft  4  thereon, until bearing against the front face of the protective sleeve  15 . At the same time, the tabs  27  are lifted and thus prevent an axial displacement of the fixing means  29  counter to the slip-on direction and thus secure the protective sleeve  15  in the axial direction on the fixing dome  10 . 
     In  FIG. 15  a further embodiment of windscreen wiper drive arrangement  1  is shown. The protective sleeve  15  is pressed onto the fixing dome  10 . Additionally, a latching arm  30  is provided, extending in the direction of the gear mechanism housing  3  and resilient transversely to the axial direction. Said latching arm comprises, as shown in  FIG. 16  in detail, at its free end a recess  31  with which it is pushed onto a latching lug  32  of the gear mechanism housing  3 . As a result of this latching, any movement of the protective sleeve is prevented relative to the gear mechanism housing  3 .