Abstract:
The invention concerns a wiper device, in particular for a motor vehicle, comprising a wiper arm ( 10   a - 10   c,    10   k,    10   l ) including a wiper rod ( 12   a,    12   c,    12   k ) for fixing a wiper blade, a fixing element ( 14   a - 14   c,    14   k,    14   l ) connected free of articulation to the wiper rod ( 12   a,    12   c,    12   k ) and at least one partial zone ( 16   a - 16   m ) having spring elasticity. It is proposed that the wiper arm ( 10   a - 10   c,    10   k,    10   l ) can shift essentially elastically from an operating configuration to at least one first stable configuration, wherein the wiper blade can be mounted and dismounted when the wiper arm ( 10   a - 10   c,    10   k,    10   l ) is in a mounted state.

Description:
BACKGROUND OF THE INVENTION 
     The invention concerns a wiper device. 
     A wiper device forming the species is known from DE 31 42 716 C2. The wiper device includes a wiper arm with a wiper rod manufactured of a spring elastic plastic, on whose free end a wiper blade can be fastened, as well as a fixing element, with which the wiper rod is connected free of articulation. The wiper rod features a constant profile having a plastic core and a plastic jacket surrounding the plastic core over its length. 
     SUMMARY OF THE INVENTION 
     The invention concerns a wiper device, in particular for a motor vehicle, comprising a wiper arm including a wiper rod for fixing a wiper blade, a fixing element connected free of articulation to the wiper rod and at least one partial zone having spring elasticity. 
     It is proposed that the wiper arm can shift essentially elastically from an operating configuration to at least one first stable configuration, wherein the wiper blade can be mounted and dismounted when the wiper arm is in a mounted state, whereby dismounting the wiper arm for the purpose of replacing the wiper blade is advantageously avoided and a comfortable, essentially wear-free folding out of the wiper arm, in particular to replace the wiper blade and for purposes of cleaning the vehicle window, can be enabled. 
     In this connection “free of articulation” means that the wiper rod and the fixing element are connected without a materially designed swivel axis around which the wiper rod and the fixing element could swivel relative to one another. Components, which due to a material deformation, in particular due to an elastic deformation, enable a relative movement between the wiper rod or partial zones of the wiper rod and the fixing element, should not be viewed in this connection as articulation and in particular should also be included in the extent of the protection, i.e., film hinges, spring elastic partial pieces, spring elastic wiper rods, etc., for example. 
     The wiper arm can be designed as one piece or as multiple pieces, whereby at least a two-piece design with a fixing element separated from the wiper rod can be advantageous because of the different requirements for the material properties. In particular a configuration in which the wiper arm remains without the essential holding force of a user should be understood in this connection as a stable configuration. In particular, a configuration in which the mounted wiper arm exerts a bearing force on the to-be-wiped surface via the wiper blade should be understood as an operating configuration. Moreover, a process essentially characterized by elastic deformations and by preservation of the material properties should be understood as essentially a spring elastic shift. In this connection, however, the shifting process can also include the opening of a fixation and/or plastic deformations of individual components that are used for dampening the fold-out movement, for example. 
     In one embodiment of the invention it is proposed that the wiper arm in a demounted state features a second stable configuration varying from the first stable configuration, into which the wiper arm can essentially be shifted in a spring elastic manner. A stable delivery position can be advantageously provided by means of the second stable configuration along with the first stable configuration that is useable as the mounting position. In addition, if the operating configuration is included in the quantity of configurations occurring when shifting the wiper arm from the first to the second stable configuration, a force acting in the direction of the second stable configuration and thus in the direction of the to-be-wiped surface can be achieved in the operating configuration. 
     In a further embodiment of the invention it is proposed that the spring elastic partial zone features at least one curved formation whose convex side points in a first direction in the first stable configuration and in the second stable configuration points in a second direction, in particular a direction essentially opposing the first direction. Upending the curved local formation can produce, in terms of the equilibrium, a great change in the shape of the wiper arm so that the local formation can assume a switch function for the shape of the overall wiper arm. In this case, the wiper arm can feature one or more independent and/or connected-in-series and/or connected-in-parallel formations of this type. Particularly suitable are spherical-cap-shaped or oval (in a top view) formations, by means of which a bistable component with a spring elastic partial zone can be realized in a simple way. In addition, a high flexural strength, at least in the wiper movement direction, can be guaranteed. 
     If the spring elastic partial zone features at least one hole in the area of the curved formation, it is possible to advantageously achieve that during the shifting movement between a stable configuration and the operating configuration or another stable configuration where only small elastic deformations of the material occur, whereby material fatigue can be advantageously prevented. The size and the shape of the hole can be advantageously selected to determine the forces acting during the shifting movement. 
     An additional realization of a bistable wiper arm can be achieved by the spring elastic partial zone featuring at least one arched section, which in the first stable configuration has a curvature in a first direction and in the second stable configuration a curvature in a second direction, whereby a bistable component can be manufactured in a cost effective manner, which can be advantageously integrated into the longish shape of the wiper arm. 
     In addition, it is proposed that at least one section of the spring elastic partial zone be under initial tension in at least one stable configuration. The initial tension represents a parameter, which can be advantageously used to set the force to be used for the shifting movement. In the configuration, having initial tension the section can be fixed with positive engagement, frictional engagement or a substance-to-substance bond. 
     In addition, a comfortable shifting of the configurations into each other can be advantageously achieved if the wiper device has at least one limit stop in the area of the spring elastic partial zone, via which limit stop a force can be initiated in a targeted manner in the area of the spring elastic partial zone during a shifting process between the stable configurations. The force can be initiated, in this case, via the limit stop directly in the spring elastic partial zone or via a limit stop arranged outside of the spring elastic partial zone and via an arm of a lever. A force exerted on the wiper arm can be concentrated advantageously on an active section of the spring elastic partial zone, in particular, directly on a spherical-cap-shaped formation or on an initially tensioned arc and strong deformations leading to material fatigue can be excluded. In addition, a transition point can be advantageously set by the limit stop during a shifting movement between two configurations. The transition point separates two phases during the shifting movement, in which a restoring force drives the wiper arm in the direction of different configurations. 
     If the limit stop is formed on the fixing element and/or if the spring elastic partial zone is integrated into the wiper rod as one piece, the number of components of the wiper arm and the assembly expense can be advantageously reduced. Other embodiments where the limit stop represents an independent component or is formed on components of the motor vehicle other than fixing element are also conceivable. In this case, a one-piece design of the spring elastic partial zone with the fixing element is also conceivable. 
     A cost effective product can be achieved if the spring elastic partial zone is designed as a punched bent sheet metal part. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Additional advantages are yielded from the following description of the drawings. Exemplary embodiments of the invention are depicted in the drawings. The drawings, the description and the claims contain numerous features in combination. The person skilled in the art will also observe individual features expediently and combine them into additional, meaningful combinations. 
       The drawings show: 
         FIGS. 1-3  A section of a wiper arm with a spring elastic partial zone in a first stable configuration, in a working configuration and in a second stable configuration 
         FIGS. 4 and 5  A longitudinal section through a partial zone of the wiper arm from  FIGS. 1 and 3   
         FIG. 6  A fixing element of an alternative wiper arm that is free of articulation, as well as a section of a bistable component of a wiper rod 
         FIGS. 7-9  The bistable component of the wiper rod according to  FIG. 6  in a form with a pre-impressed curvature, as well as in the raw form 
         FIGS. 10 and 11  A bistable component for another alternative wiper arm in a raw form and in a form with an extended center section 
         FIGS. 12-14  The wiper arm with the bistable component according to  FIG. 10-11  in a first stable configuration, in a working configuration and in a second stable configuration 
         FIGS. 15 and 16  An arched component and a frame in a loose and in a welded state for another alternative wiper arm 
         FIGS. 17-20  Schematic representations for manufacturing a bistable component by initially tensioning individual sections in a front and side view 
         FIGS. 21-32  Spring elastic components for additional alternative wiper arms in configurations with and without initial tension 
         FIGS. 33-37  “Snapshots” of a process in which another alternative wiper arm with limit stops is shifted from an operating configuration to a first stable configuration and back 
         FIG. 38  The wiper arm according to  FIG. 33-37  in a mounted state shortly before a transition point 
         FIGS. 39 and 40  A section of the wiper arm from  FIGS. 33-38  in a spatial representation in two configurations 
         FIGS. 41-43  A section of another alternative wiper arm in spatial representations in two configurations 
     
    
    
     DETAILED DESCRIPTION 
       FIG. 1  depicts a section of a wiper arm  10   a  of a wiper device of a motor vehicle. The section shows a fixing element  14   a , a spring elastic partial zone  16   a  and section of wiper rod  12   a . All parts  12   a ,  14   a ,  16   a  are connected with one other free of articulation. The wiper arm  10   a  features a first stable configuration, in which mounting and dismounting a wiper blade (not shown) is possible when the wiper arm  10   a  is in a mounted state. In this case, the spring elastic partial zone  16   a  has a curved, spherical-cap-shaped formation  18   a  with a round hole  22   a  arranged in the center, whose convex side  20   a  points in the direction  36   a  of a vehicle window (not shown here) ( FIGS. 1 and 4 ). A design of the formation without a hole (not shown here) is also possible. 
       FIG. 2  depicts the wiper arm  10   a  in an operating configuration and  FIG. 3  shows a second stable configuration, in which the wiper arm  10   a  can be shifted to spring elastically out of the first stable configuration via the operating configuration. From the operating configuration in  FIG. 2 , a tension force of the spring elastic partial zone  16   a  drives the wiper arm  10   a  in the direction  36   a  of the second stable configuration ( FIG. 3 ). When the wiper arm  10   a  is in a mounted state the tension force in the operating configuration generates a bearing force of the wiper blade on the vehicle window. In the operating configuration and in the second stable configuration, the convex side  20   a  of the curved formation  18   a  points in a direction opposing the direction  36   a  of the vehicle window ( FIGS. 2 and 5 ). 
       FIGS. 6-9  depict a fixing element  14   b , as well as a bistable component  50   b  of an alternative wiper arm  10   b  that is free of articulation. A separate component  50   b  ( FIG. 9 ), that is flat in a raw state, is fastened to the fixing element  14   b  as a spring elastic partial zone  16   b . The component  50   b  has a curved formation  18   b  in a state that is depicted in  FIGS. 7 and 8 . In the area of the curved formation  18   b , an elongated hole  22   b  arranged in the center transverse to the longitudinal direction and extending in the longitudinal direction of the component  50   b  has been removed. Under the effect of force, the formation  18   b  can be upended in a direction opposing an original direction  36   b  ( FIG. 8 ), whereby the wiper arm  10   b  switches between two stable configurations. 
     A bistable component  50   c  for another alternative wiper arm  10   c  is depicted in  FIGS. 10 and 11 . The component  50   c  that is flat in a raw state ( FIG. 10 ) has two parallel longitudinal sections  30   c , which subdivide the component  50   c  into a center section  40   c  and two outer sections  42   c . To manufacture the bistable component  50   c , the center section  40   c  is stretched by plastic deformation of the material into an arc shape ( FIG. 11 ), whose convex side  20   c  in a first stable configuration of the wiper arm  10   c  (depicted in  FIG. 12 ) points in a first direction  36   c  facing a vehicle window and in a operating configuration depicted in FIG.  13  and a second stable configuration depicted in  FIG. 14  points in a second direction opposing the first direction  36   c.    
     In a further alternative wiper arm, a bistable component  50   e , which is depicted in  FIGS. 15 and 16 , is comprised of a frame  38   e  and a center section  40   e  stretched into an arc. The parts  50   e ,  40   e  are depicted loose in  FIG. 23  and welded in  FIG. 24 . 
       FIGS. 17-20  provide schematic representations of how a bistable component  50   m  can be manufactured by initially tensioning at least one section of a flat component  50   m  with three longish sections  40   m ,  42   m , as depicted schematically in  FIG. 17 . In  FIG. 18 , a tensile force  52   m  acts on the center section  40   m  and a compressive force  54   m  acts on the outer sections  42   m . The outer sections  42   m  are initially tensioned elastically into arcs, as shown in  FIG. 20  in a side view of the component  50   m  from  FIG. 18 .  FIG. 19  shows that a compressive force  54   m  on the center section  40   m  and a tensile force  52   m  on the outer sections  42   m  produce an arched curvature of the center section  40   m.    
     Several exemplary embodiments of spring elastic components  50   d ,  50   d - 50   j  in accordance with the principle depicted in  FIGS. 17-20  are depicted in  FIGS. 21-32 . In this case, high flexural strength in the wiper movement direction is achieved in the exemplary embodiment depicted in  FIGS. 21 and 22  due to a transverse connection  56   d  between the two outer sections  42   d . In the configuration depicted in  FIG. 22  a compressive force  54   d  acts on the transverse connection  56   d  in the direction of the longitudinal extension of the component  50   d . The compressive force  54   d  is distributed to the two outer sections  42   d , which are initially stressed in an arched manner. In this configuration, the component  50   d  can be fixed in the area of the transverse connection  56   d  during installation in a wiper arm, whereby the internal tension force built up in the sections  42   d  is supported on section  40   d.    
     A simplified manufacturing and assembly process and increased stability is offered by the exemplary embodiment depicted in  FIGS. 23 and 24 , in which a center section  40   e  is shortened by a crimp  32   e  as compared with the outer sections  42   e  so that said sections can tension under pressure into arcs, which are fixed in their positions by tensile stress in the center section  40   e  of the component  50   e . The exemplary embodiment depicted in  FIGS. 25 and 26  uses the sample principle of shortening two outer sections  42   g  of a component  50   g  using crimps  32   g , thereby tensioning a center section  40   g  into an arc. 
     Derived from the exemplary embodiment in  FIGS. 21 and 22  is the exemplary embodiment depicted in  FIGS. 27 and 28 , in which crimps  32   h  in three sections  40   h ,  42   h  of a component  50   h  represent three sections of a groove, which supports the fixation of a configuration with initially tensioned sections  42   h . In the configuration depicted in  FIG. 28 , said configuration can be fixed by the insertion of a spring in the groove formed by the crimps  32   h . An analogous embodiment for fixing an arched, initially tensioned center section  40   i  is depicted in  FIGS. 29 and 30 . 
     Another possibility for fixing an arched, initially tensioned center section  40   j  is depicted in  FIGS. 31 and 32 . Both the center section  40   j , as well as two outer sections  42   j  have lateral recesses  34   j , which in the initially tensioned configuration depicted in  FIG. 31  complete a rectangular hole, through which fixing pins are inserted during mounting in a wiper arm, which pins prevent the component  50   j  from automatically reverting to a relaxed configuration, as depicted in  FIG. 32 . 
       FIGS. 33-37  show “snapshots” of a process, in which another alternative wiper arm  10   k  depicted in a longitudinal section and having limit stops  24   k  and  26   k , which are formed on the fixing element  14   k , is shifted from an operating configuration to a first stable configuration and back. 
     A spring elastic partial zone  16   k  with an initially tensioned center section  40   k  is formed as one piece on a wiper rod  12   k . A force  46   k ,  46   k ′ acts on a free end  44   k  of the wiper rod  12   k  during the process ( FIG. 38 ). In this connection, it is a counter force  46   k ′ compensating for a bearing force in the operating configuration ( FIGS. 33 and 37 ). 
       FIGS. 34 and 36  depict transition configurations, during which the forces  46   k ′ and  46   k  acting on the free end  44   k  of the wiper rod  12   k , act in the direction or counter direction of a vehicle window  28   k . The forces  46   k ′ and  46   k  are initiated each at a point on an arched center section  40   k  of the spring elastic partial zone  16   k  by means of the limit stops  24   k  and  26   k . The limit stops  24   k  and  26   k  effectively and directly produces a change in the configuration of the wiper arm. Upending the center section  40   k  occurs suddenly as soon as the wiper arm  10   k , when shifting of the wiper arm  10   k  from a first stable configuration ( FIG. 35 ) to an operating configuration ( FIGS. 33 and 37 ), has passed through a specific configuration depicted in  FIG. 38 , in which the free end  44   k  of the wiper arm  10   k  has a specific distance  48   k  from the limit stop  26   k  to the vehicle window  28   k . A wiper blade can be advantageously mounted and dismounted in the stable configuration shown in  FIG. 35  when the wiper arm  10   k  is in a mounted state. 
       FIGS. 39 and 40  show a section of the wiper arm  10   k  from  FIGS. 33-37  in spatial representations. Both the fixing element  14   k , as well as the wiper rod  12   k  are designed as punched bent sheet metal parts, whereby the lower limit stop  26   k  and the upper limit stop  24   k  are formed on separate, riveted-together components of the fixing element  14   k.    
       FIGS. 41-43  show a section of another alternative wiper arm  10   l  in spatial representations in two configurations. A fixing element  14   l  of the wiper arm  10   l  features limit stops  26   l  and  24   l , which are formed as one piece from the sheet metal of the fixing element  14   l . The lower limit stop  26   l  is realized by crimped-over flaps of the fixing element  14   l.