Abstract:
An electrical contact-making connection has a metallic pin, a base part with a plug-in opening and an electrical conductor routed to the plug-in opening. The plug-in opening includes an oblique wall surface area oriented at an angle a other than zero with respect to a predefined plug-in direction. On this area, the pin is deflected as it is inserted into the plug-in opening in such a way that it comes to rest on at least one further inner wall surface area of the plug-in opening, while exerting a lateral pressure. The conductor is clamped in the plug-in opening by the deformed pin.

Description:
BACKGROUND OF THE INVENTION 
     FIELD OF THE INVENTION 
     The invention relates to an electrical contact-making connection and a controller incorporating the electrical contact-making connection. The contact-making connection is formed of a pin which is inserted into a base part formed with a plug-in opening configured for receiving the pin. 
     For the purpose of making electrical contact between a metal pin and an electrical conductor, it is already known to use a crimp connection, in which the conductor and the pin are together inserted into a compression bush and are then clamped to each other there. In making the clamped contact, it is disadvantageous that only low fit and assembly tolerances can be accepted, that is to say that high dimensional stability in the production of the connecting elements (pin, conductor, compression bush) is necessary, and that precise prepositioning of the same must take place before they are put together. As a result, the production of the contact-making connection is made more difficult, and costs for making the contact are increased. 
     In the case of a vehicle controller installed in an engine or a transmission, because of the extreme ambient conditions prevailing there (temperatures between −40° and 140° C., vibration accelerations up to 33 g) and the poor accessibility in the event of a failure, high requirements are placed on the reliability of the contact. In the case of the known crimp connection there is the risk that loosening or, in some cases, even detachment of the electrical clamp contact can occur as a result of fatigue of the compression bush material. 
     In German Utility Model DE 295 01 821 U1, a description is given of a connecting device for connecting lines to multiple plug sockets. A base part of the connecting device has oblique plug-in openings which open into cable ducts which run horizontally and in which electrical conductors to be firmly clamped are laid. Pins project from a plug part of the connecting device and, when the pins are inserted into the plug-in openings in the base part, they are deflected by the latter and, in the process, clamp the lines routed in the base part. 
     Published, Non-Prosecuted German Patent Application DE 40 20 339 A1 describes a connecting device in which a fine wire can be fixed by a pin in a tapering sleeve. The pin is equipped with notched teeth, in order to assume a blocking frictional seat in the sleeve. 
     A clamping element in the form of a leaf spring twisted about its longitudinal axis is described in Published, Non-Prosecuted German Patent Application DE 16 65 815 A. By rotating the spring counter to its prestress, conductor ends located in a sleeve are clamped against one another, achieving high contact forces. 
     In German Patent DE 197 12 842 C1, a description is given of a controller for a motor vehicle. A housing cover of the controller encloses electrical conductors, whose conductor ends project from the housing cover and project into openings in the base plate. Conductor tracks of a flexible printed circuit board are routed to the openings and are crimped there with the projecting conductor ends. 
     European Patent EP 0 394 327 B1 describes a central electrical unit for a motor vehicle. This contains, inter alia, a distributor plate with lead-through slots which have holding openings in which first electrical contacts in the form of wire clips are compressed with second electrical contacts in the form of pins and are connected electrically in the process. 
     In Published, European Patent Application EP 0 507 062 A2, a description is given of a plug strip, which is positively shielded against electromagnetic interference, for electronic controllers in motor vehicles. 
     SUMMARY OF THE INVENTION 
     It is accordingly an object of the invention to provide an electrical contact-making connection and a controller for a motor vehicle having an electrical contact-making connection that overcomes the above-mentioned disadvantages of the prior art devices of this general type. 
     With the foregoing and other objects in view there is provided, in accordance with the invention, an electrical contact-making connection, including: 
     an electrically conductive pin defining a first electrical contact; 
     a base part having a plug-in opening formed therein for accommodating the electrically conductive pin, the plug-in opening is defined by an inner oblique wall surface area oriented at an angle a other than zero with respect to a predefined plug-in direction of the electrically conductive pin and by at least one further inner wall surface area disposed to be offset axially from the inner oblique wall surface area, the plug-in opening deflects the electrically conductive pin as the electrically conductive pin is inserted into the plug-in opening and, during insertion the electrically conductive pin is deformed plastically, the electrically conductive pin resting on and exerting a lateral pressure on the at least one further inner wall surface area; and 
     an electrical conductor routed to the plug-in opening and defining a second electrical contact, after the electrically conductive pin has been inserted in the base part the electrical conductor is clamped between the electrically conductive pin and the inner oblique wall surface area and/or the electrically conductive pin and the at least one further inner wall surface area of the plug-in opening. 
     The invention is based on the object of providing an electrically secure contact-making connection and a motor vehicle controller whose electrical contact-making connections to electrical subassemblies (actuators, sensors) disposed outside the controller are able to withstand high mechanical and thermal stresses. 
     On the oblique wall surface area provided according to the invention, deliberate plastic deformation of the pin is brought about within the plug-in opening. The plastic deformation is achieved during and as a result of pressing in the pin. The consequence of this is that the pin, in the course of being pressed in further, strikes (at least) a further inner wall surface area of the plug-in opening. The clamping of the electrical conductor to the pin, which implements the making of the electrical contact, takes place on (at least) one of these inner wall surface areas. 
     One advantage of the invention resides in the fact that no great dimensional stability requirements relating to the lateral pin and plug-in opening dimensions (pin diameter, opening diameter) have to be met. 
     Nor is any particularly positionally accurate mutual alignment of the connecting parts (pin, plug-in opening) necessary before they are plugged together. It is merely necessary to ensure that the pin encounters the oblique wall surface area which reshapes it as it is inserted into the plug-in opening. 
     Because of the low requirements on fit and assembly tolerances, the production of the contact-making connection according to the invention is simple and may be automated in a cost-effective manner. 
     From the point of view of suitability for automation, it is also advantageous that the plug-in forces to be applied can be predefined in a very defined way, since they depend decisively on the material properties (plastic deformability, flexural elasticity) of the pin and not—as in the case of common plug-in connections—on the fitting accuracy of the pin and of the plug-in opening. 
     Furthermore, the dimensioning of the electrical conductor in relation to its thickness is not critical either. Even for varying conductor thicknesses, it is always possible to ensure, by adequately large dimensioning of the plug-in opening and suitable prepositioning of the pin relative to the plug-in opening, that the conductor cannot shear off at an opening edge of the plug-in opening during the insertion operation. 
     The electrical conductor is preferably a moveable tab of a flexible printed circuit board with a conductor track running on it. Before the pin is inserted, the tab can overlay the plug-in opening, so that it is drawn into the plug-in opening by the pin during the insertion operation. 
     The desired degree of deformation of the pin can be influenced and deliberately predefined by a suitable selection of the material properties (flexural elasticity, plastic deformability) of the pin and of the angle a of the oblique wall surface area. As a result, characteristic properties of the contact-making connection, such as the number of contact areas of the pin on the inner wall surface of the plug-in opening (at least two according to the invention), for example, or the spring behavior of the pin between the contact areas can be predefined as desired. 
     A specific variant of the contact-making connection according to the invention is characterized by the fact that the plug-in opening is formed as a passage opening running through the base part, that after the contact-making connection has been produced, a plastically deformed end section of the pin projects from the passage opening on the outlet side, and that the plastically deformed projecting end section engages behind the rear of the base part. In this way, in addition to achieving the making of an electrical clamp contact, it is also possible to achieve the positive mechanical tensile anchoring of the pin on the base part. 
     With the foregoing and other objects in view there is further provided, in accordance with the invention, a controller for a motor vehicle, including: 
     a base plate; 
     a plastic frame connected to the base plate and having a plug-in opening formed therein and defined by an inner oblique wall surface area oriented at an angle a other than zero with respect to a predefined plug-in direction and at least one further inner wall surface area disposed offset axially from the inner oblique wall surface area; 
     a circumferential seal; 
     a housing cover coupled to the base plate in an oil-tight manner via the circumferential seal and defining a cavity formed between the housing cover and the base plate; 
     an electronic control unit accommodated in the cavity; 
     a flexible printed circuit board electrically connected to the electronic control unit and routed out between the base plate and the housing cover, the flexible printed circuit board having a tab functioning as a first electrical contact; and 
     a pin functioning as a second electrical contact and in an area of the housing cover disposed outside of the circumferential seal, the pin projecting from the housing cover into the plug-in opening making electrical contact there with the tab of the flexible printed circuit board, the pin being deflected as it is inserted into the plug-in opening and being deformed plastically such that it comes to rest on the at least one further inner wall surface area and exerts a lateral pressure on the at least one further inner wall surface area, the pin clamping the tab between at least one of the pin and the inner oblique wall surface area and the pin and the at least one further inner wall surface area of the plug-in opening. 
     Other features which are considered as characteristic for the invention are set forth in the appended claims. 
     Although the invention is illustrated and described herein as embodied in an electrical contact-making connection and a controller for a motor vehicle having an electrical contact-making connection, it is nevertheless not intended to be limited to the details shown, since various modifications and structural changes may be made therein without departing from the spirit of the invention and within the scope and range of equivalents of the claims. 
     The construction and method of operation of the invention, however, together with additional objects and advantages thereof will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a diagrammatic, fragmented, exploded, sectional view of a contact-making connection according to the invention; 
     FIG. 2 is a fragmented, plan view of a base part shown in FIG. 1 with a flexible printed circuit board disposed above it; 
     FIG. 3 is a fragmented, sectional view of the contact-making connection shown in FIG. 1 after being joined together; 
     FIG. 4 is a fragmented, plan view of the base part shown in FIG. 3 after being joined together; 
     FIG. 5 a  is a fragmented, sectional view of a variant of the contact-making connection shown in FIG. 3 with four contact areas of a pin on an inner wall surface of a plug-in opening; 
     FIGS. 5 b  and  5   c  are sectional views showing a cross-section of the pin; 
     FIG. 6 is a fragmented, sectional view of a further variant of the contact-making connection shown in FIG. 3 with the pin engaging behind the base part; 
     FIG. 7 is a partially broken-away plan view of a transmission controller with a housing cover cut open; and 
     FIG. 8 is a sectional view of the controller shown in FIG. 7 along the line VIII—VIII. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     In all the figures of the drawing, sub-features and integral parts that correspond to one another bear the same reference symbol in each case. Referring now to the figures of the drawing in detail and first, particularly, to FIG. 1 thereof, there is shown a plug-in part  1  and a base part  2 , which are to be connected mechanically to each other in order to form an electrical contact between a metallic pin  3  and an electrical conductor  6 ,  6   a . The parts  1 ,  2  can be produced, for example, from a hard plastic. 
     The pin  3  is firmly anchored in the plug-in part  1  and projects from the latter in the area of a contact surface  1   a . A free length of the pin  3  is designated a plug-in depth T. A pin axis A is oriented perpendicular to the contact surface la in the example shown. The pin  3  consists of a material that is plastically deformable and can be bent elastically, consisting preferably of a metal or a metal alloy. 
     The pin  3  may have, for example, a cross section S 1  like a circular disk of diameter D or else a rectangular cross section S 2  with side lengths D 1  and D 2  (see FIGS. 5 b  and  5   c ). 
     The base part  2  may be constructed in the form of a plate, which is provided with an oblique bore  4 . The oblique bore  4  has an oblique wall surface area  5  (here extending over the entire length of the oblique bore). The cross-sectional shape of the oblique bore  4  may correspond to the cross-sectional shape S 1 , S 2  of the pin  3 , but is dimensioned to be significantly larger than D, D 1 , D 2 . 
     On its upper side, the base part  2  has a mating contact surface  2   a , on which the conductor  6  rests, the latter being implemented here in the form of a flexible printed circuit board  6 . The flexible printed circuit board  6 , of which only a subsection can be seen in FIG. 2, has a printed circuit board tab  6   a  which, before the plug-in part  1  is joined to the base part  2 , is disposed above the plug-in opening  4  and at least partly overlaps the latter. A conductor track  7 , consisting of copper, for example, extends in the printed circuit board tab  6   a.    
     The printed circuit board tab  6   a  can be constructed either (as illustrated in FIG. 2) as an extension of the flexible printed circuit board  6  projecting beyond its edge, or else as a tongue-like stamped-free section in the printed circuit board  6 . 
     The following text gives an explanation, referring to FIGS. 1 to  4 , as to how an electrical contact is made between the pin  3  and the conductor track  7  by joining the two parts  1 ,  2 . 
     First, the plug-in part  1  is prepositioned in relation to the base part  2 , as illustrated in FIG.  1 . The necessary positional accuracy of the prepositioning is less and less critical the greater the opening of the oblique bore  4  is dimensioned (in relation to the diameter or the side lengths of pin  3 ). Referring to FIG. 1, one can see a predefined plug-in direction indicated by an arrow Y. Preferably, the opening of the oblique bore  4  has lateral dimensions, as referenced from the predefined plug-in direction, that are more than 25% larger than the lateral dimensions of the pin  3 . 
     The plug-in part  1  is then lowered onto the base part  2  in the predefined plug-in direction indicated by the arrow Y. The predefined plug-in direction Y and the oblique wall surface area  5  are oriented at an angle α to each other, the direction of the pin axis A here corresponding to the plug-in direction Y, that is to say the pin axis A and the oblique wall surface area  5  are also oriented at the angle α to each other. As it is lowered, a free end  8  of the pin  3  encounters the conductor track tab  6   a  and bends the latter, around an opening edge  9  of the oblique bore  4 , into the oblique bore  4 . 
     As it is lowered further, the free end  8  of the pin  3  with the conductor track tab  6   a  positioned in front encounters the oblique wall surface area  5  at a location P 1  and is deflected on the latter (FIG.  3 ). The deflection effects both a (reversible) flexurally elastic deflection and an (irreversible) plastic deformation of the pin  3 . The latter leads to a change of shape, which is necessarily required for the present invention, of the pin  3  (see the bend in the pin axis A at A 1 ) in the oblique bore  4 . 
     The angle α can lie, for example, in the range between 10° and 40°. 
     Because of the deflection experienced at P 1 , as it is brought down further, the free end  8  of the pin  3  again strikes a (further) inner wall surface area of the oblique bore  4  at the location P 2 . Here too, a change to the shape of the pin  3  takes place (bending of the pin axis A at A 2 ). 
     Because of the flexural elasticity of the pin  3 , a compressive spring force is built up between the contact areas P 1 , P 2 . 
     The action of making electrical contact between the pin  3  and the conductor track  7  exposed on the tab surface  6   a  is implemented at P 1  by clamping the same between the pin  3  and the oblique wall surface area  5 , under the action of the compressive spring force. 
     Pin materials with suitable deformation and elasticity properties are Cu—Sn (for example CuSn 6 ) and Cu—Zn are alloys. 
     Suitable values for the angle α can lie, for example, between 10° and 25°. 
     FIG. 4 shows the connecting joint illustrated in FIG. 3 in a plan view, the plug-in part  1  not being drawn for illustrative reasons. Between the opening edge  9  and an outer circumference of the pin  3  there is an interspace Z, which is greater than a thickness W of the printed circuit board tab  6   a . This prevents the printed circuit board tab  6   a  from being sheared off at the opening edge  9  as it is inserted into the oblique bore  4 . 
     FIG. 5 shows a variant of the contact-making connection illustrated in FIG. 3; this initially differs essentially from the latter only in the fact that the plug-in depth T is greater and the angle α is also greater. The result of this is that at locations P 3 , P 4 , further contact areas of the pin  3  with the inner wall surface of the oblique bore  4  are produced, and these increase the parting strength and contact-making reliability of the connecting joint. The result is a snake-like course of the pin  3  within the oblique bore  4 . 
     A further variant of a contact-making connection according to the invention is shown in FIG.  6 . Here, the plug-in opening is configured as a passage hole  4   a  which runs through the base part  2 . This makes it possible for an end section  3   a  of the pin  3 , projecting from the passage hole  4   a , to roll over behind the base part  2 , because of the deflection experienced at P 2 , and to come to rest with its free end  8  on the rear of the base part  2 . In this way, a self-securing contact-making connection is provided. 
     FIG. 7 shows a plan view of a controller  12 , which is provided for installation in an automatic transmission of a motor vehicle. A housing is formed by a cover  16  made of plastic, which for illustrative purposes is cut open and only drawn in part, and a base plate  10  disposed underneath. The cover  16  is fastened (in a manner not illustrated), as a supporting element for the housing, to a hydraulic selector plate of the transmission. Encapsulated in the cover  16  are electrical feed lines  17 , which lead to non-illustrated actuators and sensors disposed in the transmission. 
     The base plate  10  preferably consists of aluminum and, in its central area, bears an electronic control unit  18 . In its circumferential area, the base plate  10  is provided with outwardly directed extensions  14  with holes  13 , by which the base plate  10  can be coupled to the cover  16  via screw connections or the like. 
     The base plate  10  is surrounded by a plastic frame  11 , which adjoins the base plate  10  in a flush manner and continues the latter outward with a flat surface. The connection between the base plate  10  and the plastic frame  11  can be implemented via latching hooks  15 , which are fitted to the inside of the plastic frame  11 . 
     The plastic frame  11  forms a base part. According to the invention, it has a large number of the plug-in openings  4  or  4   a , which can be configured in accordance with the examples shown in FIGS. 1 to  6  and can extend over the frame profile in one or more rows. 
     FIG. 8 shows a cross-sectional illustration of the controller  12  shown in FIG. 7, along the line VIII—VIII. The flexible printed circuit board  6  surrounds the electronic circuit  18  on all sides, its conductor tracks making electrical contact with the electronic circuit  18 . 
     A central section  16   a  of cap-like configuration belonging to the housing cover  16  has a circumferential side wall  19 . Formed in a bottom area of the side wall  19  is a circumferential groove, into which an annular seal  20  is inserted. The flexible printed circuit board  6  is led out of the housing  10 ,  16  of the transmission controller  12  between the annular seal  20  and the base plate  10 . 
     Radially outside the circumferential side wall  19 , the cover  16  is provided with a skirt-like circumferential edge  21 , which forms a chip guard for a chamber-like annular space  22  located between the circumferential side wall  19  and the circumferential edge  21 . 
     The feed lines  17  project from the cover  16  (corresponding to the plug-in part) into the chamber-like annular space  22  in the form of the pins  3 . In the plug-in openings  4 ,  4   a , they are clamped according to FIGS. 1 to  6  to the printed circuit board tabs  6   a  of the flexible printed circuit board  6 , and there make contact with the conductor tracks  7  on the latter. As a result of making electrical contact, the electrical connection between the electronic circuit  18  and the actuators/sensors external to the housing is implemented. 
     The inner wall of the plug-in opening  4 ,  4   a  can be lined with a bush  100  made of a hard metal, in order to have adequate hardness for the deflection of the pin  3  during the construction of the connection or else to ensure long-term stability of the contact-making connection. 
     Because of the high permissible part and assembly tolerances and the simple joining operation, with the electrical contact being made automatically, the controller illustrated can be installed cost-effectively and, because of the spring behavior of the contact-making connections used, has good resistance to vibration and temperature changes.