Patent Publication Number: US-10777932-B2

Title: Electric plug with elastic press-on elements

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims the benefit of the filing date under 35 U.S.C. § 119(a)-(d) of German Patent Application No. 102018203628.4, filed on Mar. 9, 2018. 
     FIELD OF THE INVENTION 
     The present invention relates to an electric plug and, more particularly, to an electric plug having an outer housing and an inner housing which can be plugged into the outer housing along an assembly direction. 
     BACKGROUND 
     Electric plugs having an inner housing which can be plugged into an outer housing are frequently provided with large tolerances, yet are intended to be free of play. Plugs of this type are frequently used, for example, as a chamber block inserted into a receptacle housing, in particular in the motor vehicle industry. The tolerance can lead to overpressing during mounting, as a result of which high plugging forces arise and it becomes more difficult to remove the inner housing during maintenance. Play can also occur between the inner and outer housing, as a result of which the service life of the electric plug is shortened due to vibrations and movements of the inner housing relative to the outer housing. Furthermore, the contacts of a mating plug can be lost or damaged as a result of the vibrations. 
     SUMMARY 
     An electric plug comprises an outer housing, an inner housing adapted to be plugged into the outer housing along an assembly direction, and a press-on element. The press-on element is adapted to be deflected elastically transversely to the assembly direction and produces a press-fit connection between the inner housing and the outer housing. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention will now be described by way of example with reference to the accompanying Figures, of which: 
         FIG. 1  is a sectional side view of an electric plug before mounting; 
         FIG. 2  is a sectional perspective view of an electric plug according to another embodiment in a mounted state; 
         FIG. 3  is a sectional top view of the electric plug taken along line  3 - 3  of  FIG. 2 ; 
         FIG. 4  is a perspective view of an elastic press-on element of an electric plug according to another embodiment; and 
         FIG. 5  is a perspective view of another elastic press-on element of an electric plug according to another embodiment. 
     
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENT(S) 
     Embodiments of the present invention will be described hereinafter in detail with reference to the attached drawings, wherein like reference numerals refer to the like elements. The present invention may, however, be embodied in many different forms and should not be construed as being limited to the embodiments set forth herein; rather, these embodiments are provided so that the disclosure will convey the concept of the invention to those skilled in the art. 
     An electric plug  1  according to an embodiment shown in  FIG. 1  has an inner housing  4  which can be plugged into an outer housing  2  along an assembly direction M. 
     The inner housing  4  can be, for example, a plug strip or a chamber block, which can be connected to a complementary plug. As shown in  FIG. 1 , the inner housing  4  is punctuated by a plurality of contact receptacles  5  along a longitudinal axis L. The inner housing  4  has an elongated base body  6 , which extends along the longitudinal axis L arranged substantially parallel to the assembly direction M. The elongated base body  6  is bounded by four lateral surfaces  7 , shown in  FIG. 5 , in a direction transverse to the assembly direction M. Two adjacent lateral surfaces  7  are arranged at substantially 90° to one another and, as a result, the base body  6  has a substantially rectangular cross-section transverse to the assembly direction M. 
     As shown in  FIG. 1 , a plurality of press-on elements  8  are overmolded on the lateral surfaces  7 . The inner housing  4  and the press-on elements  8  are formed integrally as a monolithic component  10  and can be molded from a plastic, for example, by injection molding. In other embodiments, the electric plug  1  can be manufactured by 3D printing or dipping. In another embodiment, the press-on element  8  is a separate component, such as a metal spring, and can be fitted to the inner housing  4  or the outer housing  2 . 
     The press-on elements  8  can be deflected elastically transversely to the assembly direction M and serve to compensate a tolerance between the inner housing  4  and the outer housing  2  transversely to the assembly direction M, coupling the inner housing  4  and the outer housing  2  to one another by a press-fit connection. 
     Each elastic press-on element  8  has a bracket  12 , shown in  FIG. 1 , which extends outwardly from the lateral surface  7  transversely to the assembly direction M. At an end  14  of the bracket  12  facing away from the lateral surface  7  there is arranged a spring tab  16 , which extends substantially by 90° away from the bracket  12  along the assembly direction M. The spring tab  16  ends in front of an offset  17  of an end surface  18  of the inner housing  4 . The end surface  18  faces the outer housing  2  in the assembly direction M. A recess  19  is produced between the spring tab  16  and the lateral surface  7 , and the press-on element  8  has a substantially L-shaped cross-section. In an embodiment, the spring tab  16  can extend from one bracket  12  to a second bracket  12 , such that the press-on element  8  has a substantially U-shaped cross-section. 
     The spring tab  16 , as shown in  FIG. 1 , has a contact-pressure surface  20  extending transversely to the longitudinal axis L away from the inner housing  4 . In the mounted state, the contact-pressure surface  20  presses against a support surface  22  of the outer housing  2 , in order to produce a press-fit connection between the inner housing  4  and the outer housing  2 . During the mounting, a normal force acts upon the contact-pressure surface  20  and the spring tab  16  is deflected transversely to the assembly direction M in the direction of the inner housing  4 . The contact-pressure surface  20  tapers in the direction of the support surface  22 , and thus has a chamfer  23  at the edge. The chamfer  23  runs along the longitudinal axis L and facilitates the plugging-in in the assembly direction M, as a small resistance must be overcome in comparison with a stepped configuration. 
     As shown in  FIG. 1 , the outer housing  2  has a receptacle  24  into which the inner housing  4  can be inserted. The receptacle  24  is bounded transversely to the assembly direction M by a plurality of lateral walls  26  and has a substantially rectangular cross-section complementary to the inner housing  4 . The support surface  22  of the outer housing  2  is formed by a prominent portion  28  protruding in the direction of the inner housing  4 . In an embodiment, the outer housing  2  is water-tight and surrounds the inner housing  4  in a protective manner after mounting. 
     As shown in  FIG. 1 , the inner housing  4  has an internal width  30  transverse to the assembly direction M between two contact-pressure surfaces  20  arranged on opposite lateral surfaces  7  in relation to the inner housing  4 . The internal width  30  of the inner housing  4  is greater than an internal width  32  between the opposite support surfaces  22  of the outer housing  2 . An internal width  33  of the inner housing  4  without contact-pressure surfaces  20  is smaller than the internal width  32 , as a result of which a gap  34  would arise between inner housing  4  and outer housing  2  during plugging-together without press-on elements  8 . By way of the press-on element  8 , when the plugging-together is carried out, the gap  34  is closed by the contact-pressure surface  20  and the support surface  22  is contacted. As a result, the inner housing  4  can be fixed in a play-free manner in the outer housing  2 . 
     During the mounting, each press-on element  8  is deflected elastically transversely to the assembly direction M in the direction of the inner housing  4 . The press-on element  8  presses with its contact-pressure surface  20  against the corresponding support surface  22  and produces a press-fit connection between the outer housing  2  and the inner housing  4  by the elastic force. In the mounted state, the internal width  30  of the inner housing  4  corresponds substantially to the internal width  32  of the outer housing  2 . A tolerance is compensated by the elastic press-on elements  8 . High plugging forces during mounting, due to an over-pressing, are reduced by the elastic press-on elements  8 ; the elastic press-on elements  8  are deflected in the direction of the lateral surface  7  of the inner housing  4  by the over-dimension between the internal width  30  and the internal width  32 , and thus prevent an over-pressing. In order to produce a stable press-fit connection, the material thickness of the contact-pressure surface  20  transverse to the assembly direction M is greater than the width of the gap  34  transverse to the assembly direction M. 
     In the embodiment of  FIG. 1 , a press-on element  8  is molded on each lateral surface  7  of the inner housing  4 . As a result, a secure and tilt-free fixing of the inner housing  4  in the outer housing  2  can be ensured. Depending on spatial conditions and dimensions of the electric plug  1 , in various embodiments, at least one press-on element  8  can be arranged on a lateral surface  7 , at least two press-on elements  8  can be arranged on two mutually adjacent lateral surfaces  7  or two mutually opposite lateral surfaces  7  with respect to the inner housing  4 , or at least three press-on elements  8  can be arranged on three lateral surfaces  7 . The press-on elements  8  can be arranged on the outer housing  2  and the inner housing  4  has the complementary support surfaces  22 . In another embodiment, several mutually spaced-apart press-on elements  8  can be arranged on a lateral surface  7  along the longitudinal axis L. In an embodiment, all lateral surfaces  7  have at least two press-on elements  8 , one press-on element  8  in each case being arranged at an end of the lateral surface  7  lying along the longitudinal axis L. As a result, tilting of the inner housing  4  is prevented. 
     An electric plug  1  according to another embodiment is shown in  FIGS. 2 and 3 . In the embodiment shown in  FIGS. 2 and 3 , the outer housing  2  is constructed from two separate housing parts  35 ,  36 . A rear housing part  35  in the assembly direction M is partly surrounded by a front housing part  36  in the assembly direction M, and is connected to the front housing part  36  in a play-free manner by a press-fit connection produced by a press-on element  8 . 
     As shown in  FIGS. 2 and 3 , the inner housing  4  is inserted into the rear housing part  35  in the assembly direction M and is fixed by the press-fit connection produced by at least one press-on element  8 . The press-on element  8  with a spring tab  16  extends across a rounded corner  38  between two adjacent lateral surfaces  7  which are arranged at substantially 90° to one another. The press-on element  8  is by a collar  37 , which is provided with a recess  19  extending across the corner  38 . At each corner  38 , a spring tab  16  is arranged between the support surface  22  at the lateral wall  26  of the rear housing part  35  and the recess  19 . The spring tabs  16  each have a contact-pressure surface  20  protruding in the direction of the support surface  22 . The contact-pressure surface  20  has the shape of a segment of a sphere, the apex being directed towards the support surface  22 . The contact-pressure surface  20  is complementary to the support surface  22 , which is formed by the rounded corner between the mutually adjacent lateral walls  26 . 
     As shown in  FIG. 3 , a gap  34  extends between the inner housing  4  and the rear housing part  35 . The contact-pressure surface  20  projects into this gap  34  and is supported on the support surface  22  of the rear housing part  35 , fixing the inner housing  4  in the rear housing part  35  in a play-free manner with the press-fit connection. The spring tab  16  can be deflected in the direction of the recess  19 , in order to avoid high plugging forces during plugging of the inner housing  4  into the rear housing part  35 . 
     The inner housing  4 , as shown in  FIGS. 2 and 3 , has an elongated base body  6  along the assembly direction M and four contact receptacles  5  along the longitudinal axis L. The contact receptacles  5  are arranged in a square and each receive a contact of a complementary mating plug. The base body  6  has a rear section  40  enclosed by the rear housing part  35  in the assembly direction M. The rear section  40  has an internal width  30  transverse to the assembly direction M, the internal width  30  is approximately as large as the internal width  32  of the receptacle of the rear housing part  35 , in order to ensure play-free fixing of the inner housing  4  and of the rear housing part  35 . 
     The rear section  40 , as shown in  FIGS. 2 and 3 , has a plurality of elastic press-on elements  8  on the lateral surfaces  7 , on the front and rear ends in the assembly direction M. As a result, tilting of the inner housing  4  in the rear housing part  35  is prevented. 
     The base body  6  narrows uniformly with a step  42  shown in  FIG. 2  which runs around the base body  6  transversely to the assembly direction M. The narrowed section  44  extends from the step  42  counter to the assembly direction M and forms the front end of the elongate base body  6  in the assembly direction M. 
     As shown in  FIGS. 2 and 3 , the rear section  40  is surrounded by the rear housing part  35 . The front housing part  36  extends along the longitudinal axis L and is plugged onto the inner housing  4  in the assembly direction M. For this purpose, the front housing part  36  has an opening  46  along the longitudinal axis L. The opening  46  is bounded by a wall  47  transversely to the assembly direction M and has a substantially rectangular cross-section transverse to the assembly direction M. The opening  46  has a contour which is complementary to the narrowed section  44 . In an embodiment, additional elastic press-on elements  8  can be arranged on the narrowed section  44 , in order to produce a play-free and tilt-free fixing of the inner housing  4  in the front housing part  36 . The front housing part  36  extends along the longitudinal axis L in the assembly direction M as far as the limit stop on the step  42 . 
     At the limit stop on the step  42 , the front housing part  36  has a shoulder  48 , shown in  FIG. 2 , with which the opening  46  is widened, and extends further in the assembly direction M. The front housing part  36  surrounds the rear housing part  35 . The front housing part  36  has a housing interlock  50  on one side transversely to the assembly direction M. The housing interlock  50  has a latching arm which can be latched on a latching nose of the rear housing part  35 ; the latching nose stands proud of the lateral wall  7  transversely to the assembly direction M. As a result, inadvertent opening during operation and the inner housing  4  slipping out counter to the assembly direction M is prevented. 
     The front housing part  36  has an elastic press-on element  8  on at least one side of the opening  46  transversely to the assembly direction M, the elastic press-on element  8  is molded from the wall  47  of the front housing part  36 . The elastic press-on element  8  has a spring tab  16 , which extends along the longitudinal axis L and protrudes in the direction of the lateral wall  26  of the rear housing part  35  transversely to the assembly direction M and is pressed against an outer surface of the lateral wall  26  of the rear housing part  35 , the outer surface is directed towards the wall  47  of the front housing part  36 . In this embodiment, a material thickness of the spring tab  16  corresponds to the material thickness of the wall  47 . As a result, the front housing part  36  is connected to the rear housing part  35  by a press-fit connection produced by the elastic press-on element  8 . 
     The spring tab  16  is molded by a cutout of the wall  47 , and as shown in  FIG. 2 , the cutout extends along the longitudinal axis L and is connected to the wall  47  at both ends  51 ,  52  of the cutout lying along the longitudinal axis L. The spring tab  16  has the contact-pressure surface  20  which extends substantially parallel to the longitudinal axis L, and two spring arms  54 ,  56  which extend in each case from one end  51 ,  52  to the contact-pressure surface  20 , at an angle which is inclined with respect to the rear housing part  35  along the longitudinal axis L. The elasticity of the press-on element  8  transverse to the assembly direction M is ensured by the spring arms  54 ,  56 . 
     With the elastic press-on element  8 , a tolerance between the elements to be plugged in and the receiving elements can be overcome. A tolerance can lead to an overpressing and play between the elements, as a result of which these elements can be damaged by movement and vibrations. With the elastic press-on elements  8 , when there is an overpressing, the press-on element  8  is deflected in the direction of the normal force acting upon the press-on element  8  during plugging-in, and the high plugging forces owing to the overpressing are reduced. Furthermore, the play in the plugged state is minimized or set to zero by the press-on elements  8 , which produce a press-fit connection between the inner housing  4  and the outer housing  2  or between the front housing part  36  and the rear housing part  35  of the outer housing  2 . The dismounting and maintenance of the electric plug  1  is simplified by the press-fit connection, as only a low tensile force is required in order to remove the inner housing  4  from the outer housing  2 , for example. Due to the elasticity of the press-on elements  8 , vibrations occurring can be absorbed dynamically by the press-on elements  8  and movement of the inner housing  4  relative to the outer housing  2  is restricted. Thus, the wear on the electric plug  1  is reduced and the service life is lengthened. 
     A press-on element  8  according to another embodiment for a plug  1  is shown in  FIG. 4 . The press-on element  8  of  FIG. 4  is molded by a pair of collars  37  which run around the inner housing  4 , project transversely to the assembly direction M, and are spaced apart from one another in the assembly direction M. The collars  37  are arranged parallel to one another and are punctuated by a recess  19  on at least one lateral surface  7  of the inner housing  4  in the assembly direction M. The recess  19  extends transversely to the assembly direction M parallel to the lateral surface  7 . Each collar  37  has a spring tab  16  between the recess  19  and the end of the collar  37  facing away from the lateral surface  7  of the inner housing  4 . The spring tab  16  extends transversely to the assembly direction M parallel to the lateral surface  7 . Thus, the press-on element  8  has a substantially U-shaped cross-section transverse to the assembly direction M. 
     The spring tabs  16 , as shown in  FIG. 4 , have a contact-pressure surface  20  which projects away in the assembly direction M and connects the two spring tabs  16  to one another in the direction of the lateral surface  7 . The contact-pressure surface  20  extends between the surfaces of the spring tabs  16  facing one another and on the surface of the spring tabs  16  facing away from the lateral surface  7 . The contact-pressure surface  20  terminates, in the assembly direction M and counter to the assembly direction M, in a chamfer  23  running towards the surface of the spring tab  16  facing away from the lateral surface  7 , in order to facilitate a plugging-in and unplugging. 
     A press-on element  8  according to another embodiment for a plug  1  is shown in  FIG. 5 . The press-on element  8  is arranged on an inner housing  4  on a lateral surface  7  at an end  58  lying to a rear in the assembly direction M. The press-on element  8  has a pair of brackets  12  arranged parallel to one another, which project from the lateral surface  7  of the inner housing  4  at opposite corners  38  of the lateral surface  7  transversely to the assembly direction M. The brackets  12  are connected to one another by a spring tab  16 , which extends transversely to the assembly direction M. The spring tab  16  is spaced apart from the lateral surface  7  transversely to the assembly direction M by a recess  19 , which extends between the brackets  12  and between lateral surface  7  and spring tab  16 . 
     The press-on element  8  shown in  FIG. 5  has a substantially U-shaped cross-section transverse to the assembly direction M. The spring tab  16  can be deflected in the direction of the receptacle when there is an application of force, preventing a high plugging force. The spring tab  16  has a contact-pressure surface  20  protruding in the direction away from the lateral surface  7 . The inner housing  4  is supported with the contact-pressure surface  20  on the outer housing  2  when the plug  1  is plugged-together. Depending on dimension and spatial conditions of the plug  1 , differently configured press-on elements  8  can be arranged on the inner housing  4  and/or on the outer housing  2 .