Abstract:
The use of a control module having at least one housing part and a multi-layer printed circuit board as the electrical connection between the inner space of the housing and components that are situated outside of the housing part is described. The multi-layer printed circuit board is the carrier for the electrical components of an electronic circuit, and is at the same time the thermal contacting to a housing part and/or a cooling element, particularly a hydraulic plate of the transmission, for a transmission control installed in an automatic transmission.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    The present application is a divisional application of U.S. patent application Ser. No. 12/452,126, filed Apr. 8, 2010, which is the national stage entry of International Patent Application No. PCT/EP2008/055811, filed on May 13, 2008, and claims priority to German Application No. DE 10 2007 029 913.5, filed in the Federal Republic of Germany on Jun. 28, 2007, each of which is expressly incorporated herein in its entirety by reference thereto. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The present invention relates to the use of a control module for a transmission control installed in an automatic transmission. 
       BACKGROUND OF THE INVENTION 
       [0003]    A control unit known from published German patent document DE 40 23 319 C1 has a printed circuit board substrate in the form of a flexible printed circuit board foil laminated onto a plate. The printed circuit board substrate is equipped on both sides with electrical components which form an electronic circuit. The components are covered by two housing parts placed on the top side and the bottom side, respectively, of the printed circuit board substrate. Outside of the area covered by the printed circuit board substrate covered by the housing parts, a device plug connector part is situated on the printed circuit board substrate which is connected to the components via printed conductors of the printed circuit board substrate and is used for connecting the control unit to an external cable harness. The known control unit is intended to be installed in the engine compartment of a vehicle. 
         [0004]    Moreover, a control unit is known from published German patent document DE 195 28 632 A1 which has a printed circuit board substrate equipped with electrical components which is covered on the top side and the bottom side by housing half-shells. The half-shells are fastened on the printed circuit board substrate using threaded fasteners. A power component situated on the printed circuit board substrate generates heat during operation which is dissipated, via through-contacts underneath the power component, to a heat-conducting layer on the bottom side of the printed circuit board substrate and from there to a housing part which is in contact with it. 
         [0005]    In addition, an electric control unit for a transmission designed as a control module is known from published international patent document WO 2006/066983 in which a device plug connector and a sensor are situated on a substrate whose electrical terminals are connected to a housing interior via a flexible conductor foil and are contacted there, via wire connections, to a circuit part manufactured separately. 
       SUMMARY OF THE INVENTION 
       [0006]    According to the present invention, the use of a control module for a transmission control installed in an automatic transmission is proposed. The control model is suitable, in a particularly cost-effective and simple manner of manufacturing, for attachment to an automatic transmission. Control units that are installed in automatic transmissions are contacted, besides the unit plug connector and an electronic circuit part of mutually connected electrical components, to a plurality of additional electrical components, such as actuators and/or sensors. The control module provided advantageously has only one single common printed circuit board substrate, and this is a multilayer printed circuit board. The printed circuit traces of the printed circuit board substrate are used not only for the electrical connection of those electrical components which form an electronic circuit part on the printed circuit board substrate that is covered by housing parts, but also for connecting the circuit part to additional electrical components, outside the covered part of the printed circuit board substrate covered by the housing part or, if a plurality of housing parts is provided, outside the part of the printed circuit board substrate covered by the housing parts. 
         [0007]    At least one contact point may be advantageously electrically connected to a sensor connector part which is applied on the printed circuit board substrate. In addition it is possible to provide at least one contact point on the printed circuit board substrate outside the area covered by the housing parts which is electrically connected to an electrohydraulic actuator, an electrically actuatable pressure control valve, for example, or a counter-contact of another transmission component. 
         [0008]    Electrical components, such as a sensor connector part, for example, may advantageously be situated outside of the area of the printed circuit board substrate covered by the housing parts and directly on the printed circuit board substrate. Other contact points on the printed circuit board substrate outside the area covered by the housing parts may be electrically connected to actuators which are situated at a spatial distance from the printed circuit board substrate. 
         [0009]    It is particularly advantageous that the outer areas of the printed circuit board substrate, which are not covered by the at least one housing part, and the device plug connector parts and the at least one contact point are provided with a protective coating. A plate-shaped printed circuit board substrate having a first side, a second side facing away from the first side, and a circumferential front side may advantageously include as the protective coating a coating applied to the first side and the second side and an edge cover applied to the circumferential front side. The protective coating may include a copper layer, a coat of varnish, or another suitable passivating layer which advantageously prevents diffusion of transmission oil, water and other harmful media into the substrate. 
         [0010]    For improving heat dissipation, at least one housing part may be designed to have a plane surface to be placed on a cooling element provided for heat dissipation, in particular a hydraulic plate of a motor vehicle transmission. 
         [0011]    A further improvement of heat dissipation results from the fact that at least one heat generating electrical component, situated on a first side of the printed circuit board substrate, is thermally connected via through-contacts to a heat-conducting layer on a second side of the printed circuit board substrate facing away from the first side. To further improve the heat dissipation, the heat conducting layer is in heat-conducting contact with a housing part and/or a cooling element. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0012]      FIG. 1  shows a cross section through an electric control unit according to the present invention, having sensors and actuators situated thereon, mounted on a hydraulic plate of a transmission. 
           [0013]      FIG. 2  shows a top view onto the printed circuit board substrate of the control unit without sensors, actuators or housing parts. 
           [0014]      FIG. 3  shows an enlarged detail from  FIG. 1 . 
           [0015]      FIG. 4  shows a detail of a cross section of the printed circuit board substrate, according to another exemplary embodiment of the present invention. 
           [0016]      FIG. 5  shows a cross-section through a further exemplary embodiment of the present invention, the device plug connector part not being depicted for the sake of simplicity. 
           [0017]      FIG. 6  shows a detail of a fourth exemplary embodiment. 
           [0018]      FIG. 7  shows a detail of a fifth exemplary embodiment. 
       
    
    
     DETAILED DESCRIPTION 
       [0019]      FIG. 1  shows a cross section through a first exemplary embodiment of the present invention. Electric control unit  1  according to the present invention includes a printed circuit board substrate  2 , which may be designed as a single-layer printed circuit board or a multi-layer printed circuit board or as a flexible printed circuit board foil laminated onto a metal plate or as an injection-molded part having printed conductors embedded therein or may be designed in other ways. The printed circuit board substrate has an essentially plate- shaped design having a first side  15 , a second side  16  facing away from the first side, and a circumferential front side  31 . On first side  15  and second side  16 , printed circuit board substrate  2  is provided in a locally limited area with electrical components  11  which form an electronic circuit  9 . Of course, components  11  may also be applied only on one side of the printed circuit board substrate. The area equipped with components  11  is indicated by a dashed line in  FIG. 2 . 
         [0020]    Electrical components  11  are electrically connected to one another via printed conductors  12  of printed circuit board substrate  2 . The printed conductors may pass through one or multiple layers of the multi-layer substrate. In addition to printed conductors  12  for wiring components  11 , further printed conductors  13  and printed conductors  14  are situated on the printed circuit board substrate which lead to remote areas of printed circuit board substrate  2  outside the area occupied by electronic circuit  9  on first side  15  and second side  16 . As is apparent in  FIG. 2 , the printed circuit board substrate has a maximum length a and a maximum width b which are dimensioned in such a way that as little material waste as possible is created. The surface area of printed circuit board substrate  2  is adapted to the conditions of a motor vehicle transmission. As is apparent in  FIG. 1 , components  11  belonging to electronic circuit  9  are covered on first side  15  by a housing part  3 , while components  11  on second side  16  are covered by a second housing part  4 . For example, housing parts  3 ,  4  may be designed as metallic half-shell parts, as press-bent parts, for example. As is best apparent in  FIG. 3 , first housing part  3  and second housing part  4  may be angled multiple times in the edge area in a known manner, so that a circumferential sealing ring  17  may be placed between the angled area of the respective housing part and printed circuit board substrate  2 . Using screw connections  18  or other suitable means, first housing part  3  and second housing part  4  may be fastened to printed circuit board substrate  2 , the respective circumferential sealing ring  17  being pressed together between the assigned housing part and printed circuit board substrate  2  and electronic circuit  9  being sealed to the outside. 
         [0021]    Printed conductors  14  of printed circuit board substrate  2  connect electrical components  11  to a device plug connector part  6  which is situated outside the area on the printed circuit board substrate covered by housing parts  3 ,  4 . Device plug connector part  6  is used to connect control unit  1  to an external cable harness. It is important that outside the area covered by housing parts  3 ,  4  and outside the area on printed circuit board substrate  2  covered by device plug connector part  6  at least one contact point  21  is situated which is used for contacting an additional component of the control unit. The at least one contact point  21  may be designed in the form of a metallic surface or a through-contact, for example. 
         [0022]    As is shown in  FIG. 1 , the additional component may be a sensor connector part  7 , for example. Sensor connector part  7  is used for a connection to a rotational speed sensor and is electrically connected to two contact points  21  on the printed circuit board substrate with the aid of two contact pins  30 . Contact points  21  are connected to electronic circuit  9  via printed conductors  13  as it is illustrated in  FIG. 2 . Sensor connector part  7  may be mechanically fastened to printed circuit board substrate  2  outside the area covered by housing parts  3 ,  4  and the device plug connector part. As is also apparent in  FIG. 1 , at least one additional contact point  22  is situated on the second side of the printed circuit board substrate which is connected to an electrohydraulic actuator with the aid of an electrically conductive spring contact element  29 . Electrohydraulic actuator  8  may be a pressure control valve which regulates the hydraulic pressure in a hydraulic line of the transmission. Any number of other contact points for contacting electrical components of the transmission, such as sensors, actuators, clamp contacts, and press-on contacts, for example, may be situated on printed circuit board substrate  2  outside the areas covered by housing parts  3 ,  4  and device plug connector part  6 . The contact points may be connected to the electrical components with the aid of plug contacts, solder contacts, press-in contacts, spring contacts or other suitable means. All contact points are connected to electronic circuit  9  via printed conductors of the printed circuit board substrate. 
         [0023]    Printed circuit board substrate  2 , equipped with housing parts  3 ,  4 , device plug connector part  6 , and contact points  21 ,  22 , and possibly electrical components  7 , is mounted on a cooling element  10  via a planar outside surface of second housing part  4 ; the cooling element may be a hydraulic plate of a transmission, for example. Multiple actuators  8  which are electrically connected to assigned contact points  22  on the printed circuit board substrate via spring contact elements  29  are fastened to the hydraulic plate. 
         [0024]    As depicted in  FIG. 4 , a frame part  19  filled with a casting compound  20  may be used as a housing part for covering electrical components  11  instead of half-shell-shaped housing part  3  or  4 . But it is also possible to form the housing parts, which cover components  11 , using molding compounds, foams, gels, or other means. It is important that housing parts  3 ,  4  protect components  11  on first side  15  and components  11  on second side  16  against aggressive media. 
         [0025]    A particularly preferred exemplary embodiment of the present invention is depicted in  FIG. 5 . This exemplary embodiment differs from the exemplary embodiment depicted in  FIG. 1  in that the areas on first side  15  and second side  16  of printed circuit board substrate  2  not covered by housing parts  3 ,  4  are provided with a protective coating. For this purpose, except for the outer areas occupied by device plug connector part  6  (not depicted), housing parts  3 ,  4 , and contact points  21 ,  22 , first side  15  and second side  16  of printed circuit board substrate  2  facing away from the first side are each provided with a coating  23  applied over a large area. Coating  23  preferably includes a large-area copper printed circuit board, a coat of varnish, or a suitable hard or soft coating which prevents diffusion of media such as transmission fluid or moist air, for example, into the substrate. An edge cover  24  is applied to the circumferential front side of printed circuit board substrate  2  as the protective coating. Edge cover  24  may be implemented in the form of varnish, molding compounds, extrusion, or another suitable passivation. 
         [0026]    Heat may be dissipated from components  11 , which generate heat, in different ways. As depicted in  FIG. 6 , heat generated by power components  11  on first side  15  of printed circuit board substrate  2  may be dissipated to second side  16  in a manner known per se via through-contacts  25  provided in the printed circuit board substrate. Second side  16  of printed circuit board substrate  2  is in thermal contact with a heat-conducting layer  26 . Heat-conducting layer  26  may be a copper layer, for example, which transfers the heat to housing part  4  which is in heat-conducting contact with the copper layer. The heat is dissipated from there to a cooling element  10 , on which housing part  4  rests, and which represents a hydraulic plate of a transmission. The heat may also be transferred directly from heat-conducting layer  26  to cooling element  10 . For this purpose, as depicted in  FIG. 7 , the cooling element may be provided with a platform  27  on which printed circuit board substrate  2  rests with heat-conducting layer  26  inserted in between. As depicted in  FIG. 8 , cooling element  10  may alternatively have a recess  32  and rim  28 , which encloses recess  32 , on which printed circuit board substrate  2  rests with heat-conducting layer  26  inserted in between.