FR2792270A1 - Car body earth plug construction having plug central section holding bolt held wiring connector and having outer shaft radial tooth sections forcing shaft section end outwards/gripping car body. - Google Patents

Abstract

The electrical earth plug (8) fits into a car chassis hole (2). A central hole holds a bolt onto which fits a wire connector. The plug section has an outer shaft (8b) with a toothed outer section (11). As the outer shaft section is fitted into the hole, the action of the toothed section curls back the outer shaft to grip onto the car body.

Description

The invention relates to an electrical ground connection for a vehicle

automobile.

  On motor vehicles which are currently produced,

  reads an average of ten earth connections allowing the various electrical components of the motor vehicle to be earthed. The earth connections used have a connection lug

  electrically connected to an electric cable having a tra

  poured through an opening and a screw for fixing the terminal on a

  tie of the motor vehicle, so as to ensure electrical contact between the terminal and the body. The electric cable is used to ensure the electrical contact between the component of the motor vehicle and the terminal

mass gain.

  The earth connection generally comprises a nut which is fixed on

  a part of the body or body of the motor vehicle. The screw coo-

  father with the nut to secure the connection terminal on the

  bodywork and electrical contacting of the terminal with the coach-

  laugh, by means of the screw and the nut.

  The fixing and the electrical contacting of the nut with a bodywork part or any other metallic part of the structure of the motor vehicle can be carried out by welding the nut on the structural part, at an opening in the structural part. The nut which is welded to the structure generally comprises a head which comes to bear on the structural part of the motor vehicle and a barrel which is engaged in the opening of the structural part. The nut has an internal opening or bore which is generally with a smooth wall and which has a diameter less than the diameter of the screw. The screw which is made of high hardness treated steel can achieve, when it is screwed into the bore of the nut, both the cleaning of the internal surface of this bore and the formation of a thread. Energetic tightening between the nut and the screw combined with a condition of the surfaces

  in contact without oxide guarantees the quality of the connection and the electrical contact.

  that, over time, even in the presence of a corrosive atmosphere.

  The disadvantage of this known method is that the nuts have to be welded

  on the structural part, and for example on a body sheet, at the

  calf with a through opening, to make a high-quality electrical connection, this recovery operation on the vehicle body being

an expensive achievement.

  It has also been proposed to use self-punching nuts to make the connection between the sheet and the nut, that is to say nuts which ensure both, during their engagement by punching through the sheet , their

  fixing and good electrical contact. However, the treated steel of great du-

  reté, which must be used to make the punching nuts, is not suitable for making a thread by the screw, when it is screwed inside

The nut fixed on the body.

  It has also been proposed to use a nut fixed by crimping in

  an opening passing through a body sheet of a motor vehicle.

  The nut has a head whose transverse dimensions are greater than

  res to the diameter of the hole passing through the bodywork and a barrel of general shape

  cylindrical whose diameter is less than the diameter of the hole. The cylindrical barrel

  that has an end portion opposite the head which is flared and ra-

  beaten towards the bodywork, around the hole, after engagement of the barrel in the bodywork hole, to achieve the crimping of the nut. In the case of pre-painted or oxidized sheets, or an adjustment of the crimping tool which is not sufficiently optimized, the electrical connection between the nut and the sheet is not ensured with sufficient reliability. Lock nuts

  mass intended for fixing by crimping on a sheet metal bodywork

  wind have local protuberances to ensure rotational locking

  tion of the nut. However, these local protrusions do not guarantee the

  cleaning of the contact surface to ensure high electrical quality

  as the connection of the nut with the body sheet.

  The object of the invention is therefore to propose an electrical mass gain

  sheet for a motor vehicle comprising a nut intended to be fixed by crimping in a circular hole passing through a body sheet of the

  motor vehicle, a screw intended to be fixed by screwing in a bore

  internal sage of the nut and a terminal electrically connected to the screw and to a

  electric cable, in which the nut has a head whose cross section

  versale has a dimension greater than the diameter of the circular hole passing through the sheet and a barrel having an external surface having generally

  the shape of a cylinder whose diameter is less than the diameter of the cir

  circular, one end of the barrel of the nut opposite the head of the nut being

  intended to cross the sheet and to be folded back towards the sheet to carry out the

  weaving of the nut, this ground connection providing very good contact

  electric and can be quickly and easily attached to the car

bodywork of the motor vehicle.

  For this purpose, the barrel of the nut has at least one projecting tooth

  radial on its peripheral surface having a radially outer surface

  lower inclined with respect to the axis of the cylindrical barrel, so that the lar-

  tooth gor, in the radial direction, increases from the end of the barrel towards

  the head of the nut and that the barrel has, on at least part of its length

  gueur, a section whose dimension is greater than the diameter of the hole

circular crossing the sheet.

  Preferably, the tooth projecting from the external surface of the barrel of the nut has a cross section whose lateral sides are not parallel, so that the tooth has a width in the direction

  circumferential, in its junction zone with the cylindrical surface

  drique of the barrel of the nut, to its width in its end part radially

outside.

  Preferably, the barrel of the nut has a plurality of teeth

  parts along the circumference of the nut.

  In order to clearly understand the invention, a description will now be given, by way of example, with reference to the appended figures, a ground connection according to the prior art, a ground connection nut according to the invention and an operation of setting up and fixing a socket

mass according to the invention.

  Figure lest a partial axial sectional view of a ground connection

  according to the prior art in the fixed position on a body sheet of a vehicle

car cule.

  FIG. 2A is a view in axial section of a nut of a ground connection according to the invention, during an initial stage of the installation and fixing of the ground connection on a body sheet d 'a motor vehicle. Figure 2B is an axial sectional view of the nut, in a subsequent step of fixing the ground connection, in which the nut has been crimped into the opening of the bodywork. Figure 3 is a cross-sectional view along 3-3 of the figure

  2A, showing the cross section of the barrel of the nut.

  Figure 4 is an enlarged view of the axial section of the nut shown

  felt in FIG. 2A, showing the inclination of the radially outer surface

  of the nut in the axial direction.

  In Figure 1, we see a mass gain according to the prior art desired

  generally affected by the reference 1.

  The earth connection 1 is fixed in a body sheet 2 of a

  automotive vehicle, in a through opening 2a of the sheet 2, made prior to the establishment and fixing of the ground connection, by

sheet metal drilling.

  The earth connection 1 comprises a terminal 3 fixed and electrically connected-

  ment to an electrical conductor 4 which may be a wire or a connection cable

nexion.

  The end of the electrical conductor 4 opposite the terminal 3 (not shown

  shown) is connected to an electrical component of the motor vehicle.

  The terminal 3 has an opening in which is engaged a screw which is screwed into the bore of a nut 6 which has been previously fixed by

  crimping in the opening 2a of the sheet 2.

  The nut 6 comprises a head 6a of which at least one dimension of the cross section is greater than the diameter of the hole 2a passing through the sheet 2, so that the nut can rest on a surface of the sheet 2 by

  through the head 6a and a barrel 6b which is deformed to ensure the

weaving the nut 6.

  When it is placed in the opening 2a of the sheet, the barrel 6b of the nut has a generally cylindrical shape and a diameter less than the diameter of the opening 2a. The barrel is flared and folded down towards the

  sheet 2, around the opening 2a, by the crimping tool.

  After crimping, there is generally a peripheral space.

  or clearance 7, between the edge of the opening 2a which has been slightly raised at the

  when crimping and the barrel 6b of the nut. The method of fixing by crimp

  wise of the nut 6 therefore does not provide a very high quality electrical contact between the nut and the body sheet 2. The electrical contact of the terminal 3 and of the conductor 4 with the nut 6 is ensured by tightening the screw 5

  engaged in the threaded opening of the nut 6. The quality of the electrical contact

  grounding plate, however, depends on the quality of the contact between the nut 6 and the body sheet 2 and cannot therefore be ensured

completely satisfactory.

  The internal bore of the nut in which the screw 5 of the ground connection is screwed in may be tapped before the nut is put in place and crimped, or else the tapping of a smooth hole in the 'nut 6 can be made when screwing the screw 5, in case o

  the crimp retention force is sufficient.

  In FIGS. 2A, 2B, 3 and 4, there is shown a nut 8 of a ground connection according to the invention intended to be fixed by crimping in a

  circular opening 2a of a body sheet 2.

  The weight gain according to the invention is analogous to the weight gain

  mass according to the prior art shown in Figure 1, only the nut 8 pre-

  sensing, as will be explained below, differences from the nut 6 of the earth connection according to the prior art, making it possible to ensure very good electrical contact and a very resistant fixing of the nut in the

sheet 2.

  As can be seen in particular in FIGS. 2A, 3 and 4, the nut

  comprises a head 8a of which at least one dimension of the transverse section

  dirty perpendicular to the axis 9 of the nut is greater than the diameter of the opening 2a of the sheet 2 and a tubular barrel 8b generally having the shape of a cylinder whose outside diameter is less than the diameter of the hole 2a

  of the sheet 2 and having as axis the axis 9 of the nut.

  The barrel 8b of the nut also has, projecting from its radiant surface

  cylindrical outer 10, a plurality of teeth 11 projecting into the

radial direction.

  As can be seen in FIGS. 2A and 4, each of the teeth 11 occupies only part of the length of the barrel 8b in the axial direction and the radially outer edge of the teeth 11 is inclined relative to the axis 9 of

  the nut. The radially outer edge of the tooth 11 comprises, in the direction

  tion axially and in the direction going from the end of the barrel 8b opposite the head 8a, towards the head 8a, a first part 12 'strongly inclined with respect to the axis 9 and a second part 12 more slightly inclined with respect to the axis 9. In addition, as can be seen in FIG. 3, the cross section of each of the teeth 11 in a plane perpendicular to the axis 9 comprises two

  lateral edges 13 and 13 'not parallel to each other, so that the sec-

  transverse tion of tooth 11 has a width in the circular direction

  decreasing from inside to outside of the barrel, in the direction

  radial tion. The cross section of the tooth 11 has a maximum width in its zone of connection with the cylindrical surface 10 of the barrel 8b and

  a minimum width in the circumferential direction, at its narrow end

external dialing.

  The dimension of the teeth in the radial direction and the inclination of the radially outer edges 12 ′ and 12 of the teeth 11 are such that the barrel 8b has, over at least part of its length in the axial direction, a transverse dimension greater than the diameter of circular hole 2a of

sheet 2.

  On the other hand, the inclination of the edges 12 ′ and 12 of the teeth 11 is such that the width of the tooth, in the radial direction, increases in the direction

  going from the end 14 of the barrel 8b opposite the head 8a, towards the head 8a.

  As can be seen in FIGS. 2A and 4, which represent the nut in an initial phase of the establishment of the ground connection, the nut comes to rest on the edge of the opening 2a of the sheet 2, during of its implementation

  place, via the strongly inclined edges 12 'of the teeth 11.

  The nut is then crimped inside the hole 2a of the sheet 2 using a crimping tool which includes a punch allowing

  to exert a thrust in the axial direction on the head 8a of the nut.

  Under the effect of the thrust, the barrel 8b of the nut enters the opening 2a.

  The teeth 11 of the barrel 8b which rub with force on the edge of the sheet 2, along the edge of the hole 2a, provide very effective cleaning and exposure of the facing surfaces of the sheet and the teeth. Sheet material is removed by the teeth, in the form of chips, each of the teeth forming a housing 15 with a trapezoidal cross section, in the edge of

the opening 2a of the sheet 2.

  The head of the nut 8a has, on its lower surface, an annular cavity 16, intended to receive the shavings formed during the introduction of the

  was of the nut in the opening 2a.

  The inclined flanks of the teeth 11 whose cross section is re-

  presented by the inclined edges 13 and 13 'push the metal from the sheet 2, which creates a local pressure produced and maintained by the elasticity properties of the sheet, along the edge of the hole 2a. This local pressure, which is exerted between the sheet and the teeth of the barrel 8b of the nut, is independent of the crimping conditions and depends only on the dimensions and tolerances of the nut.

  8 which is crimped. In general, the pressure of con-

  tact between the sheet and the nut depends only on the relative tolerances of the hole and the nut. When the nut has been crimped, flaring and

  folding the end part 14 of the barrel 8b of the nut 8 against the lower surface

  sheet 2 around the hole 2a, as shown in Figure 2B, the connection between the nut and the sheet is extremely strong, due to the engagement of the teeth having inclined sides inside cavities 15

  machined in sheet 2, combined with crimping.

  The shavings formed by the teeth 11, during the introduction of the nut into the hole 2a of the sheet 2, collect in the cavity 16 of the head 8a of the nut 8, when the lower bearing surface 16 'from the nut head comes

  in contact with the upper surface of the sheet 2.

  As in the case of electrical earth connections according to the prior art, a screw such as the screw 5 shown in FIG. 1 inserted into the opening of a terminal 3 electrically connected to an electric cable 4 is screwed into the bore inside of the nut 8. One can use a very hard screw in treated steel which is self-tapping and which realizes during

  its screwing, the tapping of the bore of the nut 8.

  It is possible to exert a relatively large torque on the nut 8, because it is anchored, by means of the teeth 11, in the edge of

the opening 2a of the sheet 2.

  The electrical grounding according to the invention therefore makes it possible on the one hand to ensure very good electrical contact between the nut and the body sheet of the motor vehicle and on the other hand very good attachment of

  the nut. In addition, the establishment and crimping of the nut in an or-

  pre-drilled vertices of the sheet are made very quickly and easily.

  The invention is not strictly limited to the embodiment which has been described. In the case of this embodiment, the teeth projecting from the barrel of the nut have both a radially outer edge and inclined sides, which makes it possible to obtain very good electrical contact and a

  very resistant fixing of the nut. In some cases, the teeth may pre-

  only feel a tilt in the axial direction, if you are not looking for

  che not particularly high strength of the nut connection.

  The nut which has been described comprises eight teeth 1 projecting from

  its barrel 8b and distributed in the circumferential direction of the nut, ma-

  denies that the positions of successive teeth are deduced from each other

  by a rotation around the axis 9 of the nut at an angle of 45. It would be

  likely to use a different number of teeth, greater than or less than eight. For example, we can consider a nut having six teeth whose positions

  are deduced from each other by a rotation of 60.

  One could also consider the use of a reduced number of teeth and possibly a single next tooth.

  effective electrical contact between the sheet and the nut.

  The invention applies to all types of motor vehicle and ma-

  especially for motor vehicles with a large number of

  number of electrical earth connections distributed over the vehicle body.

Claims (6)

  1.- Electrical earth connection for a motor vehicle comprising a nut (8) intended to be fixed by crimping in a circular hole (2a) passing through a body sheet (2) of the motor vehicle, a screw (5) intended to be fixed by screwing in an internal bore of the nut (8) and a terminal (3) electrically connected to the screw (5) and to an electric cable (4), in which the nut (8) comprises a head (8a ) whose cross section   has a dimension greater than the diameter of the circular hole (2a) tra-   pouring the sheet (2) and a barrel (8b) having an external surface having globa-   Lement the shape of a cylinder whose diameter is less than the diameter of the circular hole (2a), one end (14) of the barrel (8b) of the nut (8) opposite the head (8a) of the nut being intended to pass through the sheet (2) and to be folded back towards the sheet (2) to carry out the crimping of the nut (8), characterized by the fact   that the barrel (8b) of the nut (8) has at least one tooth (11) projecting radially   dial on its peripheral surface (10), having a radially outer surface (12, 12 ') inclined relative to the axis (9) of the barrel (8b), so that the width of the tooth (11) in the direction radial increases from the end (14) of the barrel (8b) towards the head (8a) of the nut (8) and that the barrel (8b)   has, over at least part of its length, a section of which a di-   mension is greater than the diameter of the circular hole (2a) passing through the sheet (2). 2. Mass gain according to claim 1, characterized in that each of the teeth (11) of the barrel (8b) of the nut (8) has a cross section in a plane perpendicular to the axis (9) of the nut having two lateral sides (13, 13 ') which are not parallel, so that the width of the tooth   (11) in the circumferential direction of the barrel (8b) of the nut (8) is decreased   health from the external cylindrical surface (10) of the barrel (8b) to the surface   radially external of the tooth (11).   3.- Weight gain according to any one of claims 1 and   2, characterized in that the radially outer surface of the tooth   (11) of the barrel (8b) of the nut (8) has a first part (12 ') and a se-   this part (12), successively in the direction of the axis (9) of the nut, in the direction from the end (14) of the nut opposite the head (8a) towards the head (8a) , the first part (12 ') of the radially external surface of the tooth (11) having an inclination greater than the second part (12), by   relative to the axis (9) of the nut (8).   4. Weight gain according to any one of claims 1 to 3,   characterized in that the head (8a) of the nut (8) has, on a surface (16 ') intended to come into contact with a surface of the sheet (2), a cavity (16), of collection of metal shavings formed by friction of the tooth (11) on the edge of the sheet (2), along an edge of the circular opening (2a), during crimping, by introduction of the barrel (8b) of the 'nut (8) in   The opening (8a) by pushing on the nut (8), in the direction of its axis (9).   5. Weight gain according to any one of claims 1 to 4,   characterized in that the barrel (8b) of the nut (8) has a plurality of   teeth (11) distributed in the circumferential direction of its surface ex- dull cylindrical (10).   6.- Method of crimping a nut (8) of an electrical ground connection   stick according to any one of claims 1 to 5, in an opening   frame (2a) passing through a sheet (2) of a motor vehicle, characterized in that the nut (8) is placed on the sheet (2), so that the barrel (8b) of the nut is partially engaged inside the opening (2a), the nut (8) resting on the edge of the circular opening (2a), via a part (12 ') of the radially external surface tooth (11), which is exerted on the nut (8) in the direction of the axis (9) of the tool to penetrate the barrel. (8b) of the nut (8) in the opening (8a), the tooth (11) of the barrel (8b) carrying out by friction the removal of metal shavings from the sheet (2) along the edge of the circular hole (2a) of the sheet (2), so as to obtain an opening (15) in the edge of the opening (2a) of the sheet (2), for receiving the tooth (11), then produced by flaring and folding towards the sheet (2)   from the end (14) of the nut (8), the crimping of the nut (8) on the sheet (2).