Abstract:
A wiper driven by a motor-driven drive shaft which has a variably-oriented axis and a guiding section of the drive shaft is held between two surfaces of a slide. One of the slide surfaces is carried by a friction plate whose external surface cooperates with a deformable member interposed between the friction plate and a stationary wall of the slide to permit a displacement of the friction plate along a transverse direction perpendicular to the plane of the plate. The formable member acts on the plate, when the guiding section is held in the slide, such that the guiding section rests simultaneously against the two surfaces of the slide.

Description:
BACKGROUND 
     The invention relates to a motor vehicle wiper system having an improved slide. 
     The invention relates more particularly to a motor vehicle wiper system of the type in which a windshield wiper is given a sweeping movement by a drive shaft which is itself made to rotate around its axis by a motor. The wiper system has a means of varying the orientation of the axis of the drive shaft. A guiding section of the shaft is held between two internal surfaces, parallel and facing one another, of a slide. 
     Such a wiper system is, for example, described in FR-A-2 753 942. The wiper system described in this document therefore has a drive shaft that is mounted so as to be mobile in rotation in a support by the intermediary of a spherical bearing that provides it with three degrees of freedom in rotation. However, in order to limit the range of motion possible for this shaft, it is provided that the lower end of the shaft be held in a slide in such a way that the shaft can no longer rotate except, on the one hand, around its axis, and on the other hand, around an axis containing the center of rotation of the spherical bearing and the longitudinal axis of the slide. The wiper system furthermore has a means making it possible to vary the orientation of the drive shaft around this second axis, particularly as a function of the angular position of the shaft in revolution around its own axis. 
     In such a system, it is important to be able to eliminate any play between the lower end of the shaft, which forms a guiding section, and the two internal surfaces of the slide, which face one another. In effect, any possibility of impact between the shaft and the slide is thus avoided, which makes it possible to limit the operating noise of the system to a great extent. 
     However, the shaft cannot be held too tightly inside the slide, under penalty of increasing the friction between the shaft and the slide, which is detrimental, on the one hand, to the efficiency of the mechanism and therefore to the energy consumption necessary to ensure movement, and on the other hand, to a satisfactory working life of the mechanism because of wear and tear due to friction. 
     SUMMARY 
     The invention therefore aims to propose a new design of a wiper system which, while making possible operation without jolts, without impact, and therefore without noise, allows better control of the tightness of the guiding section of the shaft within the slide. 
     For this purpose, the invention proposes a wiper system of the above type characterized by the fact that at least one of the internal surfaces of the slide is formed by a friction plate whose external surface cooperates with deformable means interposed between the friction plate and a stationary wall of the slide in order to permit a displacement of the friction plate along a transverse direction perpendicular to the plane of the plate, and by the fact that when the guiding section is held in the slide, the deformable means act on the plate in such a way that the section rests simultaneously against the two opposite internal surfaces of the slide. 
     According to other characteristics of the invention: 
     the deformable means consist of a plate made of elastomeric material whose interior surface rests against the external surface of the plate and whose exterior surface rests against the wall of the slide; 
     the deformable plate has raised protuberances on at least one of its surfaces; 
     the raised protuberances are in the form of bars; 
     the raised protuberances are in the form of wavy bars; 
     the raised protuberances are in the form of stubs; 
     the stubs are roughly cylindrical and solid; 
     the deformable plate has, on its surface opposite that which bears the protuberances, recesses made to correspond with the protuberances; 
     the protuberances are arranged on the interior surface of the deformable plate; 
     the protuberances are arranged on the exterior surface of the deformable plate; 
     the deformable plate is produced by extrusion; 
     the deformable plate is produced by molding; 
     the deformable plate is molded onto the friction plate; 
     the deformable plate is glued to the friction plate; 
     the deformable plate has, at its two longitudinal ends, caps which extend transversely towards the interior from the interior surface of the plate and each of which delimits a housing, the two housings being open longitudinally in the direction of one another so that each can hold a corresponding longitudinal end of the friction plate; 
     the slide has two opposite stationary walls, two friction plates, and two deformable elements which are interposed respectively between one of the plates and one of the walls, and the guiding section of the shaft is held tightly between the two friction plates; 
     the two deformable elements are produced in the form of a dampener block in a single piece; and 
     the dampener block is molded around the two friction plates. 
    
    
     BRIEF DESCRIPTION OF THE DRAWING 
     Other characteristics and advantages of the invention will appear upon reading the detailed description which follows, for the comprehension of which reference will be made to appended drawings in which: 
     FIG. 1 is a diagrammatic oblique view illustrating in a partial manner a wiper system according to the teaching of the invention; 
     FIG. 2 is a view similar to that of FIG. 1, illustrating an embodiment variant of the invention; 
     FIG. 3 is a cross section illustrating a variant of the invention; 
     FIG. 4 is a partial view of a deformable plate according to the invention; 
     FIGS. 5 and 6 are views similar to those of FIG. 4 illustrating embodiment variants of a deformable plate; 
     FIG. 7 is a section by a longitudinal and transverse plane of a dampener block with two friction plates; and 
     FIG. 8 is a diagrammatic oblique view illustrating another form of slide according to the invention. 
    
    
     DETAILED DESCRIPTION 
     Illustrated diagrammatically in FIG. 1 is a part of a motor vehicle wiper system. More precisely, we have illustrated windshield wiper drive shaft  10 , with axis A 1 , which is articulated around point C with respect to a support (not represented) by the intermediary of spherical bearing  12 . Axis A 1  passes through point C, and spherical bearing  12  theoretically gives shaft  10  three degrees of freedom around point C. 
     In order to limit the range of motion of shaft  10 , and particularly in order to eliminate one of its degrees of freedom in rotation about point C, lower end  16  of shaft  10  is held in slide  14  with a longitudinal axis. 
     Slide  14  has a stationary structural element provided with two walls  18  parallel both to axis A 1  and to the longitudinal axis of the slide. The two walls  18  delimit between them space  20  inside of which lower end  16  of shaft  10  is held. According to the teaching of the invention, shaft  10  is received between two friction plates  22  which extend parallel to walls  18 , between the two walls. 
     According to the invention, lower end  16  of shaft  10  is in contact simultaneously with the facing opposite internal surfaces  24  of each of the two plates  22 . Thus, end  16  of shaft  10  is immobilized in the transverse direction, and shaft  10  is immobilized in rotation around a longitudinal axis passing through point C. 
     For this purpose, interposed between each plate  22  and the corresponding wall  18  is deformable element  26  which, since wall  18  is stationary, acts on plate  22  transversely towards the interior. The dimensions of the whole are determined so that when end  16  of shaft  10  is held between friction plates  22 , the two deformable elements  26  are compressed between plate  22  and wall  18 . 
     According to a preferred embodiment of the invention, deformable elements  26  are produced in the form of plates made of an elastomer. 
     Each deformable plate  26  therefore rests by interior surface  28  against friction plate  22 , and by exterior surface  30 , against an internal surface of the corresponding wall  18 . 
     In the embodiment example illustrated in FIG. 1, the two interior  28  and exterior  30  surfaces of deformable plate  26  are smooth and flat. 
     By contrast, in the embodiment examples of the invention which are illustrated in FIGS. 2 and 3, deformable plates  26  are provided with raised protuberances  32  on at least one of their surfaces  28 ,  30 . 
     In these two examples, protuberances  32  are produced in the form of longitudinal bars which extend in a rectilinear manner parallel to one another. In the embodiment example of FIG. 2, protuberances  32  are borne by exterior surfaces  30  of each of the two deformable plates  26 , whereas in the embodiment example illustrated in FIG. 3, deformable plates  26  are provided with protuberances  32  on their interior surfaces  28  which are in contact with the corresponding friction plate  22 . In both cases, deformable plates  26  can, for example, be produced by extrusion and can be connected by gluing to external surface  35  of friction plate  22 . 
     Protuberances  32  make it possible to limit the contact surface between the elastomeric material and the two rigid elements, which particularly permits better control of crushing of plate  26  as a function of the force applied to it by shaft  10  via friction plate  22 . Of course, it is possible to provide for arrangement of protuberances on both surfaces  28 ,  30  of deformable plate  26 . 
     In the embodiment example illustrated in FIG. 4, longitudinal bars  32  have a profile which is not rectilinear but rather is wavy, which makes it possible to improve distribution of the forces transmitted between wall  28  and deformable plate  26 . 
     In the embodiment example illustrated in FIG. 5, deformable plate  26  has, on one of its surfaces  28 ,  30 , cylindrical stubs  34  that extend transversely in relief and that are arranged in a staggered manner. In these two last embodiments of the invention, plate  26  can, for example, be produced by molding and attached by gluing to the corresponding friction plate  22 . It is also possible to provide for molding of plate  26  on plate  22 . 
     In the example in FIG. 6, plate  26  has stubs  36  whose shape in cross section makes it possible to take best advantage of their resistance to crushing as a function of the force exerted. In effect, on that surface  28 ,  30  opposite the surface on which stubs  36  are formed in relief, plate  26  has recesses  38  arranged so as to correspond exactly with raised stubs  36  of the other surface. Thanks to these recesses  38 , one succeeds in maintaining a relatively constant thickness of material, which simplifies control of crushing of the plate. 
     Moreover, recesses  38  have roughly the shape of a bowl so that the force to obtain a given transverse crushing of stub  36  is roughly proportional to this crushing. 
     Of course the invention can also be used with a transversely mobile friction plate provided on only one side of the slide; associated deformable element  26  must then take up all the possible play in order to make it possible to lay the shaft against both the internal surface of the opposite wall and the internal surface of the friction plate. 
     However, when slide  14  has two friction plates  22 , it is possible to provide, as illustrated in FIG. 7, for producing deformable plates  26  associated with these two plates  22  in a single piece, for example by molding. As can be seen in FIG. 7, the two deformable plates  26  are connected, at each of their longitudinal ends, by cross pieces  40  produced integrally with them, cross pieces  40  having lug  42  that extends longitudinally in such a way as to be held between the two internal surfaces  24  of plates  22 , in order to determine the spacing of plates  22  and to ensure their attachment. Dampener block  44  formed by the two deformable plates  26  and the two cross pieces  40  can be molded around two friction plates  22 . 
     Illustrated in FIG. 8 is another embodiment of the invention in which deformable plate  26  has, at each of its longitudinal ends, caps  46  which extend transversely towards the interior from interior surface  28  of plate  26 . In each cap  46 , housing  48  is formed, which is open longitudinally in the direction of the other cap  46 . The two housings  48  are intended for holding the longitudinal ends of friction plate  22 , which can be successively engaged in the two housings by deformation of deformable element  26 . Once the two ends of plate  22  are held in housings  48 , deformable plate  26  and plate  22  are connected together. 
     Further illustrated in this FIG. 8 is a particular embodiment of stationary structure  50  of slide  14 . As can be seen in the figure, the two walls  18  are connected transversely at their longitudinal ends by transverse walls  52 . Provided in each wall  52  are spaces  54 , each intended to hold one of caps  46  of deformable element  26 . 
     The slide illustrated comprises two friction plates  22  and therefore two deformable plates  26 , each wall  52  therefore has two spaces  54 . Spaces  54  have the same transverse width as caps  46  and the same dimension in the vertical direction in such a way as to determine very precisely the position of the whole formed by deformable plate  26  and friction plate  22 . 
     Furthermore, it is possible to see that one of caps  46  of deformable element  26  has angled corner  56  which creates a lack of symmetry. The corresponding space  54  of course itself also has a complementary angled corner (not represented) so that the associated angled corners allow deformable element  26  and friction plate  22  to be mounted only in a single direction in order to ensure that the assembly thus formed is rightly positioned so that plate  22  is transversely toward the interior and deformable plate  26  is transversely toward the exterior. 
     In the two embodiments of the invention illustrated in FIGS. 7 and 8, one observes that the friction plate(s) can be mounted in a slide without any contact between the plate and the stationary structure of the slide. This arrangement is particularly advantageous because it avoids any transmission of vibration from one to the other. 
     Of course, the invention is not limited to the embodiments described, and the expert in the field will be able very simply to deduce other embodiments, particularly of the deformable plates, by simple combination of the characteristics of the different embodiments illustrated.