Abstract:
The invention relates to a controller housing, particularly for a transmission control module of a transmission of a motor vehicle. The controller housing ( 12 ) comprises a first housing part ( 24 ) and a second cover-shaped housing part ( 40 ). A circuit carrier ( 30 ) having at least one electronic component ( 52 ) is received in the first housing part ( 24 ). The first housing part ( 24 ) is configured in the shape of a basin ( 28 ), the base of which is configured as a heat dissipation surface ( 14 ) to a further housing ( 10 ).

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    The present invention relates to a control unit housing, especially for a transmission control module of a transmission of a motor vehicle. 
         [0003]    2. Description of Related Art 
         [0004]    In transmission control modules for transmissions of motor vehicles, hybrid control units, sensors and at least one plug connection for connecting the transmission control module are used these days on a vehicle cable harness of a motor vehicle. The plug connection for connecting to the cable harness is also designated as transmission plug. The transmission control modules mentioned are currently used while using ATF (automatic transmission fluid), and are exposed to very high temperature fluctuations from a temperature of −40° C. to 150° C. in the vehicle transmission. In order to protect the sensitive electronics deployed in the transmission control module from the aggressive transmission fluid (ATF=automatic transmission fluid), the aim is to accommodate the electronics in a sealed housing. In order to assure sufficient heat dissipation for the electronic components of the transmission control module, in view of the high operating temperatures mentioned, the metallic base area of the control unit housing of the transmission control module is placed against the aluminum housing of a transmission hydraulics system. This means that the metallic base area of the control unit housing contacts the aluminum housing of the transmission hydraulics system, whereby heat dissipation of the waste heat by thermal conduction takes place. 
         [0005]    One specific embodiment of a transmission control module that is already in production includes a hermetically sealed control unit housing for an electronic circuit. The hermetically sealed control unit housing itself is made up of a steel base plate that is developed to be flat, and has glazed metal pins, which makes possible the electrical contacting between the circuit and the lead frame using bonding, and a steel cover, which is tightly welded to the base plate. The electrical connection of the glazed metal pin to the sensors and plugs of the electronics module takes place by way of the lead frame. The lead frames are welded onto the glazed pins. Since the glazed pins project perpendicularly from the base plate of the control unit, it is necessary for the contact surface of the transmission hydraulics, required for heat dissipation, to form an elevated area. 
         [0006]    Published German patent document DE 196 40 466 B4 describes a metallic substrate part for electronic components or a circuit substrate, as well as a method for producing same. Published German patent document DE 196 40 466 B4 describes a hermetically sealed housing in which the glazed metal pins are not directly glazed into the floor part of the control unit housing, but into two separate parts. The two separate parts are also designated as pin strips, which after their production are welded into the floor plate. This technique has the advantage that only the small pin strips have to be heated during glazing, but the large floor plate does not have to be exposed to the high temperatures that occur during glazing. 
         [0007]    One additional specific embodiment of an electronics module, that is currently in mass production, having a sealed control unit housing, is made available based on a flexible printed circuit (FPC=flexible printed circuit) adhered onto an aluminum plate. Published German patent document DE 199 07 949 A1 describes the function of the sealed control unit housing. 
         [0008]    A flexible printed circuit board, made, for example, of a polyimide foil, adhesive, copper, adhesive, polyimide foil, is connected by continuous material to the electronic components on a circuit carrier (LTCC), for instance, adhered on. From the LTCC, bonding is carried out directly to the flexible printed circuit board. Onto the flexible printed circuit board, in turn, a plastic cover is laid having an elastomer seal inserted into it, and is rigidly connected to the aluminum plate, for instance, using a riveting connection. In this case, the heat dissipation also takes place to the housing of the transmission hydraulics system. However, because of the planar construction of the control unit housing, no raised area is necessary as was in the design approach according to published German patent document DE 196 40 466 B4. 
         [0009]    Published German patent document DE 10 2004 061 818 A1 relates to a control module. In this design approach, a control module is proposed for a transmission of a motor vehicle, which includes a carrier part. On the carrier part there is situated a control unit which has a first housing part and a second housing part and an internal housing chamber situated between the first housing part and the second housing part. At least one flexible conductor foil is provided, which is used for the electrical connection of the circuit part having electrical components that are situated outside the housing inner chamber. The control unit is situated having the first housing part lying on a contact area of the carrier part. The second housing part is situated within the contact area at the first housing part. 
       BRIEF SUMMARY OF THE INVENTION 
       [0010]    Following the design approach proposed according to the present invention, a control unit housing is provided which has a metallic part in the shape of a tub-shaped base form, as well as a cover which is preferably made of steel, the two metallic parts mentioned, that is, the tub-shaped base form and cover, being able to be connected to each other using continuous material, such as being welded together. The contact pins, for the electrical contacting, are glazed directly into the base form, i.e. the tub-shaped component. The design approach provided according to the present invention is distinguished by a superlative evenness of the floor plate. This creates only slight gaps between the circuit carrier and the floor plate, and between the floor plate and the transmission hydraulics housing, which in turn ensures good heat dissipation. Following the provided design approach according to the present invention, the contact pins are situated in such a way that a “wire bond” may be set onto the end face of the contact pins, for the contacting. The design approach provided according to the present invention also offers the possibility of absorbing, via a strain relief, mechanical forces, such as vibrations, oscillations and expansions that are caused thermally, which may occur during operation, so that the electrical contacting of contact pin to lead frame, which is produced within the scope of the laser welding for the continuous material connection, may be kept to the greatest extent free from mechanical stresses. Furthermore, the design approach, provided according to the present invention, has the advantage that it may be installed modularly, in different variants of electronics modules, and not only on particularly stressed transmissions or the like. 
         [0011]    The insertion of the contact pins ensuring the electrical contacting takes place directly by way of the glazing into the base form. The use of materials such as metal and glass, as well as welding, as the continuous material joining method used, and the glazing process of the contact pins make it possible to produce a hermetically sealed, cost-effective housing, using robust, proven processes. 
         [0012]    In particular, the tub-like base form inserted has a very high structural rigidity. Because of this, it is possible to fasten the contact pins directly in the tub-shaped base form by way of the process step of glazing it in, without the floor area of the tub-shaped base form warping in an inadmissible manner in this processing at high temperatures, and without damage being done to its dimensional accuracy. Consequently, one may do completely without welding the pin strips into the floor plate, as had been described according to published German patent document DE 196 40 466 B4. Because of the structural rigidity that goes along with the tub shape, no raised area is required to ensure heat dissipation by way of heat conduction. The area for the mechanical fixing of the transmission control module, that is the screw-on surface as well as the area required for the heat dissipation, represent a plane, so that the housing of the transmission hydraulics is able to be designed to be planar in a simple manner, which has a favorable influence on its production costs. 
         [0013]    The edge of the essentially tub-shaped base form is executed in such a way that individual regions having bores are larger than the cover that closes off the base form. The enlarged edge of the base form gives the possibility of fixing the lead frames mechanically to the control unit housing, for instance, by having plastic plugs extruded onto the lead frame plugged through the bores in the edge and subsequently being able to rivet them there. Strain relief of the lead frame is achieved thereby, so that the electrical contacting between lead frame and contact pin, which is able to be joined by way of laser welding to the base part, for example, is not exposed to any mechanical stresses. In addition, one may thus produce an easily manipulable subassembly of control unit/lead frame, which is advantageous with respect to production. 
         [0014]    The mechanical fastening of the control unit housing takes place by applying a force acting perpendicularly on the cover. The force acting perpendicularly on the cover may be implemented by a spring, for example. On the one hand, this offers the possibility of fixing the control unit housing mechanically, and on the other hand, of achieving an optimal contact pressure for the heat dissipation, via the contact pressure thus executed, at a minimum development of gaps which, as seen overall, favorably influences the heat transport via heat conduction. 
         [0015]    Because of the essentially tub-shaped structure of the base form of the control unit housing, it is possible to arrange the glazed-in, pin-shaped contact pins perpendicular to the circuit carrier. This achieves an advantageous arrangement for undertaking the wire bonding between the glazed-in contact pins and the circuit carrier. In so-called hybrid housings having horizontally glazed-in contact pins, it is true that an even connection was also made possible, but in this case, the process step of bonding is very unfavorable. In order to be able to produce a bonding connection in this instance, one would have to impress a flat surface on, in an additional work step. The horizontal arrangement of the contact pins is, in addition, unfavorable for the bonding, since it tends to pivot. 
         [0016]    In one further advantageous specific embodiment of the idea on which the present invention is based, it is provided that a metallic block shall be inserted into the tub-shaped base form of the control unit housing, which is preferably made up of a material such as aluminum. The circuit carrier is adhered onto this metallic block. The metallic block is used as a heat distributor, and offers a better dissipation of the heat in the case of particularly hot components. In addition, it is possible, according to this further specific embodiment of the idea on which the present invention is based, to adhere the metallic block into the tub-shaped base form in insulated fashion, and in this way to achieve a highly effective shielding. 
     
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING 
         [0017]    In the following text the present invention will be explained in greater detail on the basis of the drawings. The figures show: 
           [0018]      FIG. 1  shows a perspective view of a plurality of lead frames on the transmission control module having a control unit housing. 
           [0019]      FIG. 2  shows a perspective top view onto a tub-shaped housing part of a control unit housing. 
           [0020]      FIG. 3  shows a section through a control unit housing in a state of being placed against a transmission hydraulics housing and making possible heat transportation by heat conduction. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0021]    In a perspective top view,  FIG. 1  shows the lead frames that surround the tub-shaped housing part of the control unit housing on the transmission control module. 
         [0022]    The mechanical fixing between strain relief tabs  32  and rivetings  26  passing through them and lead frames  18 ,  20  and  22  takes place in such a way that the actual electrical contacting of contacting pins  36 , arranged by glazings  38 , in edge region  34  of tub-shaped housing part  24 , is decoupled. In glazings  38 , which are used for insulation and gastightness, accommodated contact pins  36  are arranged perpendicular with reference to an edge region  34  of tub-shaped housing part  24 , which considerably simplifies the development of bonding connections, especially wire bonding. 
         [0023]    One may gather from the illustration in  FIG. 1  that control unit housing  12  on the transmission control module, especially its tub-shaped housing part  24 , has the heat dissipation surface  14 , which is designed essentially as an evenly running plane surface. Reference numeral  16  designates individual fastening openings for fastening control unit housing  12  to the transmission control module, using which the latter is able to be fastened to a transmission hydraulic housing  10 , that is shown schematically in  FIG. 3 . 
         [0024]      FIG. 2  shows a perspective view of the tub-shaped housing part along with a circuit carrier lying inside it, as well as strain relief tabs situated along the circumference. 
         [0025]      FIG. 2  shows that tub-shaped housing part  24  includes an evenly developed floor area, upon which a circuit carrier  30  lies. A sidewall  56  extends perpendicular to the floor area of tub-shaped housing part  24 , and it borders on inner side  28  of tub-shaped housing part  24 . Edge  34  extends along the circumference of tub-shaped housing part  24 . Tub-shaped housing part  24 , shown in a perspective view in  FIG. 2 , may be produced cost-effectively and robustly as a deep-drawn part using sheet steel. Contact pins  36  are situated accommodated in glazings  38  along edge  34 . Contact pins  36 , which have a pin-shaped aspect, extend perpendicularly, that is, at an angle of 90° to the flat surface of edge  34  of tub-shaped housing part  24 . The arrangement of contact pins  36  along edge  34  of tub-shaped housing part  24  may be made at one or several adjacent locations or on one or several sides along edge  34 . 
         [0026]    The number of contact pins  36  accommodated in glazings  38  in edge  34  may be varied in correspondence to the requirements of the electronic circuit on circuit carrier  30 . Circuit carrier  30  is executed, for example, as an LTCC (low temperature co-fired ceramic), and it is adhered onto the floor of tub-shaped housing part  24 . Circuit carrier  30  includes the electronic circuit and is equipped with at least one electronic component (see also the sectional illustration according to  FIG. 3 ). 
         [0027]    In the illustration according to  FIG. 2 , strain relief tabs  32  are arranged in a plane along edge  34 . The arrangement of strain relief tabs  32  is dependent on the position of lead frames  18 ,  20 ,  22 , with which tub-shaped housing part  24  is to be fastened. 
         [0028]      FIG. 3  shows a sectional representation through a control unit housing, whose lower side is contacted to a plane side of a transmission hydraulic housing in a manner favoring the heat conduction. 
         [0029]      FIG. 3  shows that heat dissipation surface  14  of tub-shaped housing part  24  is placed, along a contact surface  42 , between tub-shaped housing part  24 , especially heat dissipation surface  14 , against a transmission hydraulic housing  10 . The bigger the contact surface, between heat dissipation surface  14 , on the lower side of tub-shaped housing part  24 , and the evenly designed plane surface of transmission hydraulic housing  10 , can be made, the better the heat dissipation  44  that sets in. Furthermore,  FIG. 3  shows that in cavity  66 , which is developed between tub-shaped housing part  24  and its cover part  40 , circuit carrier  30  is equipped with at least one electronic component  52 . The lower side of circuit carrier  30  forms a contact surface  46  with the floor area of tub-shaped housing part  24  between circuit carrier  30  and tub-shaped housing part  24 . Here, too, it is true that heat conduction  44  is more favorable the bigger contact surface  46  is able to be made between circuit carrier  30  and the inner side of the floor of tub-shaped housing part  24 . Heat dissipation  44  is better, the smaller the remaining gap widths between circuit carrier  30  and the upper side of heat dissipation surface  14 , and between the lower side, that is, heat dissipation surface  14  of tub-shaped housing part  24  and the upper evenly designed plane side of transmission hydraulic housing  10 , are able to be designed. 
         [0030]    The at least one circuit carrier  30  accommodates an electronic circuit on its upper side, which includes at least one electronic component  52 . The at least one electronic component  52  is electrically contacted to circuit carrier  30 , and is adhered onto circuit carrier  30  preferably by wire bonding. Circuit carrier  30  itself is also electrically contacted via bonding connections  50  to contact pins  36  that are developed pin-shaped in glazings  38 , in edge  34  of tub-shaped housing part  24 . As may be seen from the sectional representation according to  FIG. 3 , there is play between an extrusion coat  58  of first lead frames  18  and third lead frames  22  and the lateral surface of contact pins  36 , that are developed pin-shaped, so that there exists a mechanical decoupling of the pin-shaped developed contact pins  36 , and the latter contacts lead frames  18  and  22  only electrically. Mechanical tensile loads are absorbed via strain relief tabs  32 , riveting  26  and extrusion coat  58  that in each case surrounds lead frames  18  and  22 . Bonding connection  50  between contact pins  36  and circuit carrier  30  is developed in such a way that it is not stressed mechanically by tension or bending or the like. 
         [0031]    Tub-shaped housing part  24  is tightly sealed hermetically using a cover part  40 . A hermetically sealed connection between tub-shaped housing part  24  and cover part  40  is preferably generated along a sealed edge  64 , by a continuous material connection. This ensures a gas tightness of cavity  66  between tub-shaped housing part  24  and cover part  40 . The continuous material connection along sealing edge  64  between tub-shaped housing part  24  and cover part  40  is preferably produced by welding. A control unit housing  12  thus developed is now in a position to be tested electrically as a small assembly. In a subassembly thus premounted, both the tightness of inner space  66  is able to be tested, and tests at increased or reduced ambient temperature may be carried out, since the mass and the volume of the construction of control unit housing  12  are small. 
         [0032]    As one may see furthermore in the sectional representation in  FIG. 3 , cover part  40  of control unit housing  12  provided according to the present invention, that is developed as one piece, is placed against the evenly developed plane surface of transmission hydraulic housing  10 , using an adjusting spring  54 . Based on evenly developed heat dissipation surface  14  and the evenly developed upper side of transmission hydraulic housing  10 , an optimal heat introduction  44  is ensured. 
         [0033]    Outside hermetically sealed cavity  66  of control unit housing  12 , contact pins  36  accommodated in glazings  38  are preferably electrically contacted to one or more lead frames  18 ,  20 ,  22  by way of laser welding. One or more sensors or plugs of an electronic module are electrically contacted to lead frames  18 ,  20 ,  22 . As a fixing possibility, one option is, for example, screw sockets  62 , via which fastening elements  58 , such as screws, for screwing control unit housing  12  to transmission hydraulic housing  10 , may be used. 
         [0034]    Fastening openings  16  on control unit housing  12  and heat dissipation surface  14  may be developed in one plane so as to improve the thermal contacting of heat dissipation surface  14 . 
         [0035]    This permits a simple and cost-effective design of control unit housing  12  for a transmission hydraulic system. Moreover, a very favorable heat dissipation  44  may be implemented, which makes possible a reliable dissipation of the heat loss generated by the at least one electronic component  52 . 
         [0036]    In a further embodiment of the idea on which the present invention is based, a metallic block may be introduced into tub-shaped housing part  24  of control unit housing  12 , which is preferably made of aluminum. On this aluminum block, circuit carrier  30  may be fastened by continuous material, such as being adhered on. The aluminum block may advantageously be used as a heat accumulator or a heat distributor, in order to achieve a better dissipation of the heat loss of a particularly hot electronic component  52 , for example. Furthermore, it is possible to insert the block made of metallic material, in insulated fashion, into tub-shaped housing part  24 , to adhere it in, for instance, and thus achieve a highly effective shielding. The bigger the metallic block, made for instance of aluminum, is made, the higher is the heat accumulator capacity that can be achieved. 
         [0037]    The design approach provided, described above with the aid of  FIGS. 1 to 3 , in its various embodiment variants, makes it possible to produce a hermetically sealed system, especially including a gastight cavity  66  of a control unit housing  12 , a tub-shaped housing part  24  and a cover part  40 . Control unit housing  12  includes essentially the two housing parts  24  and  40 . Contact pins  36  are accommodated in glazings  38  in tub-shaped housing part  24 , cover part  40  being closed hermetically sealed (gastight) to tub-shaped housing part  24  along sealing edge  64  by way of a continuous material connection, that is, a robust process, such as welding. Tub-shaped housing part  24  and cover part  40  may be produced cost-effectively as deep drawn components. Because of the tub shape of housing part  24 , it is possible to place circuit carrier  30  or the metallic block used as heat accumulator against an evenly developed plane surface of transmission hydraulic housing  10 , to fix it there, and at the same time to assure at this area, too, the thermal contacting of control unit housing  12 . Enlarged edge  34  of tub-shaped housing part  24  offers the possibility of connecting lead frames  18 ,  20 ,  22 , which electrically contact the control unit, to control unit housing  12  in such a way that mechanical strain relief for the electrical contacting  50 ,  36  is able to be achieved by strain relief tabs  32 . The essentially pin-shaped contact pins  36  are able to be accommodated in glazings  38 , since the tub shape of housing part  24  has a very great structural rigidity. This avoids warping of the thermal contact surface, i.e. of contact surfaces  42  and  46 , as described above. Moreover, because of the design approach provided according to the present invention, especially by the tub-shaped embodiment of housing part  24  of control unit housing  12 , it may be achieved that a perpendicular arrangement of pin-shaped contact pins  36  is performed, which makes possible advantageous wire bonding having little pivoting. The compact design of control unit housing  12 , provided according to the present invention, additionally makes possible a simple functioning test, even at higher temperatures, as well as extremely simple handling. Control unit housing  12 , developed essentially as a modular unit, may also be used as a control unit in applications other than the above transmission application.