Control unit with sealed canal for cooling fluid

p0001The present invention relates to an electronic unit, in particular control device for a motor vehicle, with electrical and / or electronic components which are arranged on an upper surface of a thermally conductive electronic base plate and thermally coupled to this base plate, wherein the bottom plate is in turn thermally coupled with a coolant passage.

p0002Such electronic units are known in many versions in particular in the field of power electronics and have the advantage of being created during operation of the electrical or electronic components heat (power loss) to a coolant passage through coolant flowing (z. B. cooling liquid such as water) can be issued ,

p0003However, the problem here is more or less great risk of leakage of the coolant passage, which is accompanied by such a cooling method. Depending on the type of refrigerant used and the thus-cooled circuitry, this problem particularly in a compact design of the electronics unit then be particularly serious if escaping coolant can reach the circuit or its components due to a leak. An example of this is the water cooling of power electronics, in which the operation consists of relatively high electrical voltages. In this case, the penetration of cooling water to the electronics or the ingress of cooling water into an electronics housing could cause a short circuit, destroying devices, or even cause a fire. A leak of the coolant passage is to be expected in practice, especially when the difference between refrigerant pressure and ambient pressure is particularly great. The risk of penetration of coolant to the electronics is especially large when both the refrigerant passage and the space occupied by the electrical or electronic components room ( "electronics space") are housed within a more or less closed housing structure.

p0004One known way to minimize the above-mentioned risks, the use of a possible reliable tight welded or brazed radiator, on which a thermal grease or a thermal adhesive electronic modules or unpopulated flat sides of circuit boards attached (z. B. screwed) are. The use of solder instead of thermal paste or thermal glue is usually not practical because the electronic modules or electronic circuit board to be frequently dismantled. Furthermore, with use of solder, the risk of cracking in the solder, so that if the thermally coupled components have different thermal expansion coefficients. Apart from these drawbacks, the use of a possible reliably sealed cooler a high production cost.

p0005The <patcit id="pcit0001" dnum="JP11163572A"><text>JP 11-163572</text></patcit> discloses an electronic unit with a circuit board on the underside of a coolant tray is arranged. This coolant bath comprises at the upper end of the tub border on a seal to the outside, if necessary, can escape through the pressurized coolant. A further seal is designed to prevent the leaked, no longer pressurized coolant can reach the electronic components on the printed circuit board, but this seal is arranged in a groove in the wall of a printed circuit board which surrounds the cover and medium screws must be pressed there, which brings a high production effort.

p0006Also the <patcit id="pcit0002" dnum="US20030053294A1"><text>US 2003/0053294 A1</text></patcit> merely discloses the sealing of a coolant passage means of seals which are pressed by means of screws.

p0007It is an object of the present invention, in an electronic unit of the type mentioned to improve the sealing of the coolant passage and to reduce the risks in the event of a leak arising.

p0008This object is achieved according to the invention by a special design and arrangement of those components, which define the coolant passage. A particular advantage of the invention is that the underside of the bottom plate can enter directly into contact with the refrigerant, so a "direct cooling" can be realized.

p0009According to the invention the above object is achieved by a radiator portion having a recess and an integrally with the radiator part formed annularly on the edge of the recess closed running web, limits its inner side along with the underside of the bottom plate, the coolant passage, wherein the underside of the bottom plate is connected by a running at the dock seal assembly coolant sealed to the web, including which two respective closed ring at the upper end of the ridge extending seals between which a closed ring extending space is limited, which is connected to a leading out of the cooler part leakage passage.

p0010In this solution, the sealing of the coolant passage through a seal assembly at the bottom of the electronics bottom plate takes place. If a leak occurs in this area, it is still reliably prevented by a special design of the seal assembly that from the coolant passage escaping coolant directly to the underside of the base plate (and possibly from there in the electronics compartment) arrives. The seal assembly is in fact (at least two closed ring extending seals) formed "multi-stage", a closed ring extending "gap" between the seals is connected to a pressure-relieving in Undichtigkeitsfall leakage passage. So if befindliches in the coolant passage coolant should overcome the first seal, so that on the leakage passage in a controlled manner (eg. as of the electronics base plate away) can be discharged. Depending on the leak rate and flow resistance of the leakage passage is present at the second seal nurmehr a more or less considerably reduced coolant pressure.

p0011For all above-mentioned aspects of the invention will be appreciated that the coolant passage advantageously has at least one inlet and at least one outlet for admitting coolant or for discharging coolant, ie may have to flow through the coolant passage. For all aspects may extend through such inlet or outlet through the bottom plate, by the web or by the cooler part. Further, for each of the aspects of the invention also a plurality of coolant passages may be provided, which may be either completely separately from each other (eg. As with its own inlets and outlets) or in any way "chained" (z. B. in parallel and / or series configuration) , Thus, an outlet of a coolant passage z. B. simultaneously form the inlet of a subsequent refrigerant passage.

p0012The electronic unit according to the invention is particularly suitable for use in an elevated ambient temperature, such as those present in the engine compartment of a motor vehicle.

p0013In particular, a so-called power electronics realized electronic units can be cooled reliably and relatively safe according to the invention. Here such electronic units are of particular interest in which operatively at least one point, an electrical voltage greater than 100 V occurs and the refrigerant used as such represents a short circuit and / or flammable. A preferred application is for control units of a motor vehicle, such as engine control units, gear control units, etc., especially if they are located in the engine. For such devices, there is in practice a great need for cooling of microelectronic components, in particular so-called power semiconductor components. Electric voltages greater than 100 V occur, for example in control devices for hybrid vehicles and in control devices for the control of piezo-actuated fuel injectors.

p0014In a preferred embodiment it is provided that the base plate is designed as a housing part of an electronic module containing a part of the electrical or electronic components. Electronic modules per se are known and particularly advantageous for disassembly or interchangeability. However, the use of a module housing part as a base plate for the purposes of the present invention also has the considerable advantage that the respective housing part, for example, a flat side of a total of approximately cuboid electronic module, directly adjacent to the coolant passage, or directly contacts the coolant in contact during operation. It can often a conventional module (z. B. with a flat bottom flat side) are particularly advantageous.

p0015In a preferred embodiment it is provided that the base plate is formed as a metal plate which is attached flat against the underside of a circuit carrier for the electrical or electronic components.

p0016For the formation of the circuit substrate or the substrate may be resorted to common in the field of power electronics technologies. More generally, a layer structure of one or more interconnect layers that are structured at least partially to the formation of interconnects is (and possibly "by contact"), and one or more insulating layers (dielectric substrate) at least between adjacent wiring layers. In one embodiment, a circuit board having a ceramic substrate material and one or more wiring layers of metallic material. Advantageously, z. B. a comparatively small difference of the thermal expansion coefficients of the substrate (eg. As a ceramic material), and the common power electronics silicon material (z. B. unhoused applied silicon chips) can be realized. Obviously, however, may be provided in the context of the invention, any other circuit carrier.

p0017The above-mentioned connection of a metal plate on the underside of the circuit carrier can already during circuit board production (eg. As in a so-called DCB substrate), or subsequently, eg. As a thermal grease, a thermally conductive adhesive or soldering done. In particular, with regard to an adaptation of the thermal expansion coefficient on the one hand a circuit carrier substrate, and the other part of the metal plate used as a base plate is provided, in one embodiment, that the base plate is formed of a metal alloy, for example, AlSiC, CuW or CuMo. If the bottom plate (or a part of a plurality of base plates) from such rather "exotic" and thus expensive materials is made as to seal the cooling passage according to the invention is advantageous because the base plate can be formed in shape less complex (excluding the bridge) can. In this context it should be borne in mind also that in an embodiment according to the invention advantageously z. B. a radiator portion having a plurality of each closed ring extending and integrally formed webs can be used as a cooler part for several each relatively simple design and small-sized base plates simultaneously.

p0018The coolant is preferably a cooling liquid. When used in the electronics of a motor vehicle, the coolant passage can be supplied, for example, with the already existing cooling water of the cooling circuit for an internal combustion engine. Alternatively or additionally, the connection of the electronic unit or the extent provided coolant passage to a specially provided for the coolant circuit is possible. A particularly interesting application for the invention is present if the coolant passage for receiving a cooling agent having a pressure of at least 2 bar, in particular at least 3 bar is designed.

p0019In an advantageous for each seal in terms of ease of installation and sealing embodiment is provided that the web has a groove for the seal or grooves for the seals and / or connected via the seal or seal assembly with the web component, cooler part or base plate having a receiving groove for the seal or grooves for the seals.

p0020In one embodiment it is provided that a plurality of separately formed floor panels are provided, which are connected via a corresponding number of seals or sealing arrangements with a common radiator portion. In a sense vice versa can also be provided that a plurality of separately formed radiator parts are provided, which are connected via a corresponding number of seals or sealing arrangements with a common base part.

p0021In one development of the invention, the coolant passage is formed with a kühloberflächenvergrößernden structure. The structure may, for. Example, be formed from the material of the base plate or the cooling part or as a separately arranged structure (eg. As sheet metal). By suitable mounting or assembly of such structures or cooling plates (such as so-called "turbulators") may advantageously also specifically directed or turbulent and not laminar flow in the cooling passages or be accomplished to improve the cooling effect.

p0022As for the material of the sealing element used in the invention (s), so can this be advantageous to resort to materials as in the fluid seal are common (eg. As elastomers).

p0023In one embodiment it is provided that the seal or at least one is formed of a plurality of gaskets as sealing ring. Such a sealing ring can over its length considered z. B. having substantially uniform cross-section, in particular, for. Example, circular cross-section, may be formed. Alternatively or additionally, z. B. can gaskets (z. B. having a substantially rectangular cross-section) may be used.

p0024According to a preferred embodiment it is provided that the base part with the radiator part is detachably connected, in particular, for. Example, is screwed. In view of a good seal between the bottom plate and cooler part of a screw is preferably carried out by a plurality of bolts or screws, so that in a simple manner a uniform contact pressure can be achieved over the course of the seal (s). For this purpose it is particularly advantageous if a plurality of screw connection points approximately along the garter course of a seal over the seal considered essentially equidistant, is provided. If the sealing is done according to the invention, it is expediently to ensure that constitute such screw connection points in Undichtigkeitsfall for leaked coolant no short path from the underside of the bottom plate to the top of the bottom plate (or other areas of the electronics compartment).

p0025The invention is further described below by means of embodiments with reference to the accompanying drawings. The embodiments of the<figref idrefs="f0001">figures 1</figref>. <figref idrefs="f0003">6</figref> and <figref idrefs="f0005">10</figref> . Put it to better understand the invention the prior art, in which:<dl id="dl0001"><dt>Fig. 1</dt><dd>a schematic side view of an electronic unit,</dd><dt>FIG. 2</dt><dd>a perspective view of an electronics base plate for an electronic unit,</dd><dt>Fig. 3</dt><dd>unit according to embodiment of the invention form a schematic side view of an electronic,</dd><dt>Fig. 4</dt><dd>a schematic plan view of a plate-shaped radiator part for an electronic unit according to another embodiment,</dd><dt>Fig. 5</dt><dd>a schematic of the cooler part of <figref idrefs="f0002">Fig. 4</figref>As viewed from the opposite side,</dd><dt>Fig. 6</dt><dd>is a partially sectioned view of the use in accordance with the bottom part <figref idrefs="f0002">FIGS. 4 and 5</figref> GE made electronics unit,</dd><dt>Fig. 7</dt><dd>a perspective view of a radiator portion of an electronic unit according to another embodiment, </dd><dt>Fig. 8</dt><dd>a perspective view of a radiator portion of an electronic unit according to another embodiment,</dd><dt>Fig. 9</dt><dd>a perspective view of the cooler part of <figref idrefs="f0004">Fig. 8</figref>, From the opposite side viewing tet, and</dd><dt>Fig. 10</dt><dd>is a schematic side view of an electronic unit according to the prior art.</dd></dl>

p0026<figref idrefs="f0001">Fig. 1</figref> illustrates a first embodiment of an electronics unit 10 (here: engine control unit) in which are electrical and electronic components 12-1 to 12-5 disposed at an upper side 14 of a heat-conductive electronics bottom plate sixteenth