Signal computer systems used on board an aircraft, inter alia, for controlling safety-relevant functions, such as, for example, the autopilot system or the flight management system are air-cooled at present. The air cooling can be performed either by free convection or by forced ventilation. While in the case of free convection a cooling air flow is established merely on account of local dense differences of the air, in the case of forced ventilation additional fans are used to supply cooling air, provided by the aircraft air conditioning system, to the signal computers to be cooled. Forced ventilation enables the dissipation of greater quantities of heat from the signal computers to be cooled than free convection. However, the fans required for forced ventilation increase the weight of the aircraft and generate heat which has to be additionally dissipated. Moreover, with the fans, additional mechanical components are introduced into the aircraft. As a result, the failure probability of the cooling is increased.
A further disadvantage of the air-cooled signal computers currently used is that the computers have to be designed to ensure proper heat dissipation from the computers according to a cooling standard. This cooling standard specifies a maximum heat emission based on a standardised apparatus housing volume. In other words, the cooling standard prescribes a minimum apparatus housing volume or a minimum contact surface of the apparatus housing with the ambient air for a quantity of heat generated by a signal computer and to be dissipated to the environment. The requirement to comply with the cooling standard thus limits the possibility of constructing the signal computers so as to be more compact and powerful.
For the cooling of power electronics, it is known to use liquid heat exchangers, such as, for example, cold plates. These liquid heat exchangers are matched, with regard to their construction, exactly to the geometric dimensions of the electronic equipment to be cooled and are positioned as close as possible to the heat-emitting electronic equipment. For example, cold plates can be arranged in interspaces of the electronic equipment to cool. Liquid cooling systems are much better suited to removing large quantities of heat than gas or air cooling systems. However, in the case of a cooling system comprising cold plates it is necessary to provide, for each cold plate, two separate coolant connections connected to a corresponding coolant circuit. The assembly and in particular the maintenance of a cold-plate liquid cooling system is therefore very costly. Furthermore, the probability of a coolant leak owing to the additionally required coolant connections increases with each cold plate present in the cooling system, with the result that the availability of the electronic equipment may potentially be reduced. A further disadvantage of known power electronics liquid cooling systems is that current coolant couplings increase the differential pressure in the coolant circuit. This reduces the efficiency of the liquid cooling, since an increased pumping capacity is required to deliver the coolant liquid through the coolant circuit.
The invention is directed at the object of providing a powerful, compactly constructed and efficiently cooled aircraft signal computer system.