Patent Publication Number: US-2023146572-A1

Title: Housing for mechanical device, mechanical assembly, gear motor and associated attachment method

Description:
The present invention relates to a metal housing for a mechanical device comprising an output shaft and an assembly of a plastic barrel on the metal housing. The metal housing corresponds, for example, to a housing for a gear motor, in particular of a motor vehicle wiper device. 
     The output shafts of gear motors of wiper systems, in particular for the rear windows of motor vehicles, generally comprise an output shaft that is relatively long in order to allow them to pass through the bodywork. It is therefore necessary to use a barrel for guiding the shaft which is attached to the housing of the gear motor containing the reduction gear mechanism. 
     The prior art discloses such barrels, but these components are generally expensive and/or difficult to manufacture or to attach to the housing of the gear motor. 
     A need therefore exists for a solution in order to obtain a barrel that is inexpensive and easy to attach to the housing. Moreover, the assembly of the barrel and the housing must be such that no dirt or moisture can enter the housing, in order to preserve the service life of the reduction gear mechanism. 
     To this end, the present invention relates to a method for attaching a plastic barrel intended to guide an output shaft of a mechanical device to a housing for said mechanical device, said housing comprising a chimney delimited by an upper edge and a base, said chimney being arranged to partially surround the output shaft, the plastic barrel comprising a lateral protuberance, the method comprising at least the following steps:
         inserting a first end of the plastic barrel into the chimney of the housing until the lateral protuberance axially abuts against the upper edge of the chimney,   at least partially deforming the first end of the plastic barrel in order to form an axial counter-abutment.       

     According to another aspect of the present invention, the housing is, for example, a metal housing or a plastic housing whose hardness may be different from the hardness of the plastic of the barrel. 
     According to another aspect of the present invention, the base of the chimney is at least partially flared towards the inside of the housing and the deformation step comprises flaring the first end of the plastic barrel by plastic deformation. 
     According to another aspect of the present invention, the deformation step comprises a heating step. 
     According to another aspect of the present invention, the heating temperature is between 150 and 180°. 
     According to another aspect of the present invention, the deformation step comprises a step of applying ultrasound. 
     According to another aspect of the present invention, the plastic barrel is made from polyamide which may be filled, i.e., reinforced with glass fiber, for example. 
     According to another aspect of the present invention, the chimney of the housing comprises at least one recess and the deformation step comprises deforming the plastic barrel into said at least one recess in order to form an anti-rotation lug. 
     According to another aspect of the present invention, the mechanical device is a gear motor of a wiper device. 
     The present invention also relates to a housing for a mechanical device comprising a chimney configured to at least partially surround an output shaft of the mechanical device, the chimney comprising a base with a substantially conical inner shape flared towards the inside of said housing. 
     According to another aspect of the present invention, the housing is a metal housing. 
     According to another aspect of the present invention, at least one recess is provided in the base of the chimney in order to receive an anti-rotation lug. 
     The present invention also relates to an assembly of a housing as previously described and a plastic barrel, the plastic barrel comprising a lateral protuberance forming an abutment and delimiting a first end intended to be inserted into the chimney of the housing around the output shaft. 
     According to another aspect of the present invention, the lateral protuberance is flange-shaped. 
     According to another aspect of the present invention, the flange comprises an end part curved towards the first end. 
     According to another aspect of the present invention, the flange forms a water deflector in order to prevent droplets from entering the housing. 
     According to another aspect of the present invention, the chimney comprises an at least partially annular mating shape configured to cooperate with the lateral protuberance. 
     According to another aspect of the present invention, the first end of the plastic barrel is flared to cooperate with the flared base of the chimney. 
     According to another aspect of the present invention, the first end of the plastic barrel is deformed in order to enter the recess and form an anti-rotation lug. 
     The present invention also relates to a gear motor comprising an electric motor, a reduction gear comprising an output shaft, a housing as previously described at least partially containing the electric motor and the reduction gear and a plastic barrel forming an assembly with the housing as previously described. 
     Other features and advantages of the invention will emerge from the following description, given by way of non-limiting example, with reference to the appended drawings, in which: 
    
    
     
         FIG.  1    shows a schematic perspective view of a gear motor according to the present invention, 
         FIG.  2    shows a schematic perspective view of a barrel according to the present invention, 
         FIG.  3    shows a schematic perspective cross-sectional view of part of a housing for a gear motor according to the present invention, 
         FIG.  4    shows a schematic perspective cross-sectional view of an assembly comprising a housing for a gear motor and a barrel according to the present invention, 
         FIGS.  5 ,  6  and  7    show schematic perspective cross-sectional views of various assembly steps according to the present invention, 
         FIG.  8    shows a flowchart of the various steps of assembling the barrel on the housing according to the present invention. 
     
    
    
     In all of the figures, elements that are identical bear the same reference numbers. 
     The following embodiments are examples. Although the description refers to one or more embodiments, this does not necessarily mean that each reference relates to the same embodiment, or that the features apply only to one embodiment. Individual features of different embodiments may also be combined or interchanged to provide other embodiments. 
       FIG.  1    shows a perspective diagram of a gear motor  1  intended for a wiper device for the rear window of a motor vehicle. 
     The gear motor  1  comprises an electric motor  3  and a reduction gear mechanism (not shown) arranged in a housing  5  and connected to the electric motor  3 . The housing  5  is, for example, a metal housing or a plastic housing and may comprise attachment tabs  7  for attaching to a bodywork element, for example. Silent blocks  9  may be arranged at the attachment tabs  7  for vibration and acoustic decoupling from the bodywork element. 
     The gear motor  1  also comprises a barrel  11  made from plastic material intended to guide an output shaft  12  of the gear motor  1 . The plastic barrel  11  is, for example, made from polyamide which may or may not be filled, i.e., reinforced with glass fiber in particular or any other type of fiber helping reinforce the polyamide. In the case of a housing made from plastic material, the material of the housing and of the barrel may be different and the hardnesses of the two materials may be different. 
       FIG.  2    shows the barrel  11  alone. The barrel  11  has a cylindrical general shape and comprises a first end  11   a  referred to as the inner end intended to be inserted into the housing  5  at a chimney  5   a  of the housing  5  and a second end  11   b . The barrel  11  also comprises a lateral protuberance  11   c  which delimits the part of the barrel intended to be inserted into the chimney  5   a  of the housing  5 . The lateral protuberance  11   c  has the general shape of a flange. The flange may be curved with a first portion which extends in an annular manner around the cylinder followed by a second portion which extends parallel to the barrel  11  towards the first end  11   a , the first and the second portion being connected by a bent intermediate portion. 
     The first end  11   a  is intended to be deformed after being inserted into the chimney  5   a  of the housing  5  in order to attach the barrel  11  to the housing  5 .  FIG.  2    therefore shows the barrel  11  after it has been deformed. Before being inserted into the chimney  5   a  of the housing  5 , the first end  11   a  has a cylindrical shape (see  FIG.  5   ). 
     As shown in  FIG.  3   , the chimney  5   a  extends between an upper edge or end portion  51  and a base  52 . The upper edge  51  is carried by a cylindrical portion  53  with a first diameter D 1 . The base  52  comprises a proximal portion  54  with a second diameter D 2  greater than the first diameter D 1  and a flared intermediate portion  55  intended to receive the end  11   a  of the barrel. The upper edge  51  comprises, for example, a circumferential material recess  57  intended to receive the second portion of the lateral protuberance  11   c  and forming an annular mating shape. The flared intermediate portion  55  may also comprise once or more recesses  56 , for example three, provided on a portion of the inner circumference of the chimney  5   a  and intended to receive anti-rotation lugs  110 . The recesses  56  may be distributed at regular intervals around the perimeter of the chimney  5   a . Indeed, as will be better described hereinafter in the description, the barrel  11  is intended to be deformed after being inserted into the chimney  5   a  so that the presence of one or more recesses  56  causes the first end  11   a  of the barrel  11  to be deformed in an irregular manner around its circumference, resulting in the formation of one or more anti-rotation lugs  110  at the recess or recesses  56 , thus preventing any rotational movement of the barrel  11  in relation to the chimney  5   a . The fact that the chimney  5   a  is flared helps prevent the barrel  11  from moving in translation by creating a counter-abutment, the abutment being created by the lateral protuberance  11   c  being brought into contact with the upper edge  51  of the chimney  5   a.    
       FIG.  4    shows the barrel  11  in the assembled state in the chimney  5   a  of the housing  5  after deformation of the first end  11   a  of the barrel  11  in order to form an assembly between the housing  5  and the barrel  11 . The lateral protuberance  11   c  bears on the upper edge  51  of the chimney  5   a  and engages in a form-fitting manner around the circumferential material recess  57  provided on the upper edge  51  of the chimney  5   a  of the housing  5 . The circumferential material recess  57  therefore acts as a mating shape for the lateral protuberance  11   c  of the barrel. Thus, by covering the upper edge  51  of the chimney  5   a , the lateral protuberance  11   c  forms a moisture deflector preventing drops of water from entering at the connection between the barrel  11  and the housing  5 , helping to protect the inside of the housing  5  and in particular the reduction gear mechanism. 
     The first end  11   a  of the barrel  11  is in contact with the flared intermediate portion of the chimney and is therefore also flared. Moreover, the portions of the first end  11   a  facing the recesses  56  are deformed so as to be inserted at least partially into said recesses  56  and form anti-rotation lugs  110 . 
     Moreover, the second end  11   b  of the barrel  11  may comprise an inner portion that is narrower in order to better guide the output shaft  12  of the gear motor  1 . Furthermore, at the inner portion of its second end  11   b , the barrel  11  may comprise a groove  11   d  intended to receive a seal  13 , for example an O-ring seal or an overmolded seal, in order to ensure tight sealing between the barrel  11  and the output shaft of gear motor  1 . 
     Therefore, in the assembled state, the chimney  5   a  partially surrounds the barrel  11 , i.e., from the first end  11   a  up to the lateral protuberance  11   c  of the barrel  11 . 
     The various steps of the method allowing the plastic barrel  11  to be assembled on and attached to the housing  5  will now be described with reference to  FIGS.  5  to  7    and the flowchart of  FIG.  8   . 
     The first step  101  relates to the insertion of the first end  11   a  of the plastic barrel  11  into the chimney  5   a  of the housing  5 , as shown by the arrow in  FIG.  5   . Insertion continues until the lateral protuberance  11   c  comes into contact with the end of the chimney, as shown in FIG.  6 . The lateral protuberance  11   c  is positioned in such a way that the first end  11   a  of the plastic barrel  11  is situated opposite the flared intermediate portion  55  of the chimney  5   a  when the lateral protuberance is in contact with the upper edge  51  of the chimney  5   a.    
     The second step  102  relates to the plastic deformation of the first end  11   a  of the plastic barrel  11 . This deformation corresponds, for example, to flaring the first end against the flared intermediate portion  55  of the chimney  5   a  in order to form an axial counter-abutment and prevent any translational movement of the plastic barrel  11  in relation to the chimney  5   a , the abutment being formed by the lateral protuberance  11   c  bearing on the upper edge  51  of the chimney  5   a.    
     According to a first alternative  102   a , the plastic deformation is carried out by virtue of a step of heating the first end  11   a  of the plastic barrel  11 . In the case of a plastic barrel  11  made from polyamide (which may or may not be filled), the heating temperature is, for example, between 150 and 180° C. The deformation may be formed by a conical or substantially conical element inserted from inside the housing  5  into the first end  11   a  of the plastic barrel  11 . Pressure is applied to the conical element towards the second end  11   b  of the plastic barrel  11  while the plastic barrel  11  is held in position (the lateral protuberance  11   c  being in contact with the upper edge  51 ) in the housing  5 , resulting in the flaring of the first end of the plastic barrel  11 . In the event that the chimney  5   a  comprises recesses  56 , the conical element may comprise shapes complementary to the recesses  56 , such that the plastic barrel  11  is deformed so as to fit into the recesses  56  and form anti-rotation lugs  110 . 
     According to a second alternative  102   b , the plastic deformation of the first end  11   a  of the plastic barrel  11  is achieved by virtue of a step of applying ultrasound, for example via a sonotrode probe. Applying ultrasound helps locally heat the first end  11   a  of the plastic barrel  11 , thus making plastic deformation possible. A conical or substantially conical element similar to the conical element of alternative  102   a  may be used to flare the first end  11   a  against the flared intermediate portion  55  of the chimney  5   a  of the housing  5 . Once the first end  11   a  of the plastic barrel is flared, the plastic barrel is attached to the housing and forms an assembly. 
     Step  203  consists in positioning the mechanical device, for example a gear motor  1 , in the housing  5 , and the output shaft  12  of the mechanical device  1  in the plastic barrel  11 , as shown in  FIG.  7   . 
     The present invention is not limited to a gear motor  1  of a wiper device for the rear window of a motor vehicle but also extends to other types of mechanical devices comprising an output shaft, a housing and a plastic barrel for guiding the output shaft attached to the housing. 
     Therefore, using a plastic barrel  11  makes it possible to perform the function of guiding the output shaft  12  while limiting the weight and the cost of the barrel  11 . Moreover, the attachment of the plastic barrel  11  to the housing  5 , which may be made from a different material from the barrel  11 , for example metal, is simple and quick and also helps to limit the risk of moisture entering the housing  5  and therefore to protect the mechanism of the gear motor  1 .