Abstract:
A chill plate  30  is described for cooling an electronic control unit (ECU)  20  of an engine. The chill plate  30  comprises a housing  32  having a flat front face onto which the ECU  20  may be mounted, formed with a central pocket  36  for accommodating any components  28  protruding from the rear face of the ECU. The housing also includes flow passages  40  through which fuel may flow around at least part of the periphery of the central pocket  36  to transfer heat to the fuel from the regions of the front face  38  surrounding the pocket  36.

Description:
FIELD OF THE INVENTION 
     The present invention relates to the cooling of an electronic control unit (ECU) of an engine, in particular a diesel engine. 
     BACKGROUND OF THE INVENTION 
     Engine mounted ECUs operate in a hot and hostile environment making it necessary to take special steps to cool the engine electronic control unit, because the function of electronic components may be impaired if they are overheated. Additionally, the heat generated by the ECU will shorten the life of the ECU if not transferred away. 
     It has previously been proposed to provide a heat exchanger(commonly called a chill plate) for supporting and cooling an ECU. The chill plate comprises a coolant chamber which, in use, is connected in a supply line through which passes the fuel flowing from a fuel tank to the engine. The chill plate serves to cool the ECU module by transferring heat to the fuel supplied to the engine. The known chill plates, however, have the disadvantage that they can only be used with ECUs having a flat heat sink of conductive material to which the heat generating electronic components are attached. 
     OBJECT OF THE INVENTION 
     The present invention seeks to provide a chill plate that can be used with different types of ECU, including ECUs having components that protrude beyond the surface of a flat heat sink to be cooled. Additionally, this design can be incorporated directly into the ECU housing if appropriate. 
     SUMMARY OF THE INVENTION 
     In accordance with the present invention, there is provided a chill plate for cooling an electronic control unit (ECU) of an engine, comprising a housing having a flat front face onto which the ECU may be mounted, formed with a central recess for accommodating any components protruding from the rear face of the ECU and flow passages within the housing through which fuel may flow around at least part of the periphery of the central pocket to transfer heat to the fuel from the regions of the front face surrounding the pocket. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The invention will now be described further, by way of example, with reference to the accompanying drawings, in which : 
     FIG. 1 is an exploded front view of a chill plate of the invention, 
     FIG. 2 is an exploded rear view of the chill plate in FIG. 1, 
     FIG. 3 is a perspective view of a first type of ECU that may be mounted in the chill plate of FIGS. 1 and 2, 
     FIGS. 4 and 5 are front and rear views, respectively of a second type of ECU that may be mounted on the chill plate of FIGS. 1 and 2, 
     FIG. 6 is an exploded vertical central section through the chill plate of FIGS. 1 and 2 and an ECU of the second type, 
     FIG. 7 is an exploded perspective view of the chill plate of FIGS. 1 and 2 and an ECU of the second type, 
     FIG. 8 is an exploded perspective view of a chill plate illustrating an alternative embodiment of the present invention, and 
     FIG. 9 is an exploded view of the chill plate of FIG. 8, taken in the direction indicated by arrow  9 — 9  of FIG.  8 . 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     FIG. 3 shows a prior art type of ECU  10  that is currently available and in use in engine management systems. This ECU  10  presents no particular problem as it has a flat rear face  12  that needs to be cooled around its periphery. Such an ECU can be cooled using a flat chill plate, as already known in the prior art. 
     FIGS. 4 and 5 on the other hand show a different type of ECU  20  that is also currently in use and differs from that of FIG.  3 . On its front face, the ECU  20  has various electrical connection terminals  22 ,  24 . On its rear face, the ECU  20  has a surface  26  that needs to be cooled and a box  28  that protrudes from that surface. The parts of the rear surface  26  that need to be cooled are shown using shading lines and it will be clear that such an ECU cannot be cooled using a flat chill plate as the protruding box  28  would prevent the parts of the rear surface  26  that need to be cooled from contacting the chill plate. 
     To mitigate this problem and allow the same chill plate to be used with types of ECU described above, the invention provides a chill plate  30  that is shown in FIGS. 1 and 2. 
     The chill plate  30  is formed of two parts that are welded to each other, namely an aluminum casting  32  and a cover plate  34 . The casting defines a pocket  36  recessed into the flat front face  38  of the chill plate, which pocket is surrounded on three sides by a channel  40  of U-shaped configuration. When the cover plate  34  is welded or otherwise affixed to the channel  40  in a fluid sealing arrangement, flow conduits are formed for fuel that enters the chill plate  30  through a fuel inlet  46  and leaves through a fuel outlet  48 . Two partition walls  42 ,  44  are cast into the upper and lower sides of the channel  40 , respectively, to constrain the fuel to follow a convoluted flow path through the flow conduit to increase residence time and the effective heat transfer from the electronic components 
     In use, as may be seen from the section of FIG.  6  and the exploded perspective view of FIG. 7, the ECU  20  of FIGS. 3 and 4 can be mounted on the chill plate because its protruding box  28  can be accommodated in the pocket  36 . The chill plate is connected in series in the pipe leading from the fuel tank to the fuel injection system of the engine. The fuel follows the path shown by the arrow  50  in FIG.  7 . In particular, the fuel enters from the inlet  46 , traverses the upper side of the channel  40  twice, descends along the vertical side and traverses the lower side of the channel  40  twice before leaving through the outlet  48 . In the process, the fuel extracts heat from the periphery of the front surface  38  of the chill plate  30  which is in thermal contact with the surface  26  of the ECU  20  that requires cooling. 
     The chill plate  30  is intended for mounting directly on the engine. To reduce transmission of engine vibrations to the ECU, the chill plate has three engine mounting bosses  52  that are designed to receive rubber bushes  54  (FIG. 6) which are positioned between the bosses  52  and mounting screws  55  which attach to the engine receiving the ECU  20 . These bushes absorb shocks and vibrations and also provide thermal isolation between the chill plate  30  and the engine on which it is mounted. 
     It will be clear that the chill plate  30  can equally well accept an ECU of the type shown in FIG. 3 that has no protrusions that inhibit the surface to be cooled from being brought into thermal contact with the cooling surface of the chill plate  30 . 
     Referring now to FIGS. 8 and 9, there is shown an alternate chill plate arrangement which eliminates the need for the cover  34  and the need to have a fluid sealed joint between the cover and the chill plate. An ECU  60  like the ECU  20  described above comprises a formed housing  62  having openings  64 ,  66  for receiving the electrical connectors  24 ,  22 , respectively which are shown in FIG.  4 . The housing  62  has a series of integral peripheral bosses  68  having through holes  70  which receive mounting screws  72 . A chill plate  74  comprises a formed housing  76  of aluminum or other heat conductive material. The housing  76  has a series of peripheral bosses  78  incorporating threaded holes  80  which receive mounting screws  72  for securing the housing  62  to the chill plate housing  76 . Housing  76  has a continuous perimeter groove  82  which receives a resilient continuous seal  84  to provide a fluid seal around the perimeter of a central recess  86  in the chill plate housing  76 . As shown particularly in FIG. 9, the recess  86  receives a box  88  similar to the box  28  shown in FIG.  5 . It should be noted that the box  88  has a surface  90  defining the maximum depth it protrudes into recess  86 . This depth is selected to be closely adjacent the floor  92  of recess  86 . A fuel inlet  94  receives a fitting  96  connected to the engine fuel supply(not shown). The inlet  94  leads to the recess  86 , but a baffle  98  causes the fuel to flow through a circuitous path like the path shown in FIG.  2 . Because the surface  90  of box  88  is closely adjacent the floor  92  of recess  86 , the fuel is forced to flow around the periphery of the box  88  like the flow of the arrangement of FIGS. 1 and 2. Any fuel which passes between the wall  98  and floor  92  will be in a dead zone having no significant flow. After the fuel has traversed the periphery of the box  88 , it is deflected by a second baffle  100  which leads to a fuel outlet  102 (see FIG.  9 ). 
     It should be noted that a three point mounting system  104 , like the one described in connection with FIG. 6 is provided to secure the assembly to an engine. 
     Conventional ECUs have a metal backing plate with the result that when the ECU is fitted to a chill plate, there will be two layers of metal between the liquid coolant and the circuit components to be cooled. The present invention dispenses with the need for a separate backing plate for the ECU and instead forms the chill plate as part of the ECU housing. 
     Thus, all of the features described above can be manufactured directly into the ECU housing instead of a separate housing for high volume applications. The ECU housing would accept these features exactly the same as a separate housing and cover assembly. The ability to accept non-flat ECU&#39;s is automatically accomplished also if this design is implemented directly into the ECU housing. 
     In order to further improve the thermal efficiency of the chill plate, the flow path for fuel comprises one or more baffles such that the fuel in the chill plate is constrained to follow a convoluted path. 
     While several preferred embodiments of the present invention have been described, it should be apparent to those skilled in the art that they may be practised other than specifically shown without departing for the spirit and scope thereof.