Patent Application
20080047688
The present invention relates to a cooling system and a cooling method for cooling components of power electronics installed on board an aircraft, in particular a passenger aircraft.
Components of power electronics must be cooled on account of the heat which is generated in operation under load. The cooling of the components represents a safety feature which ensures that the components function properly.
Since in many cases air cooling does not guarantee sufficient cooling of the components of the power electronics, cooling plates 20 are used, as represented in
One disadvantage of the conventional cooling plates lies in the fact that, should a leakage occur in the cooling fluid circuit, the flow of cooling fluid through the cooling plate will no longer be sufficient, so that sufficient cooling of the components of the power electronics will not be guaranteed. The consequence would be overheating of these components.
Constant and sufficient cooling of the components must be guaranteed, in particular in the case of power electronics installed on board an aircraft, in order to prevent possible failure of the components on account of overheating. Overheating of the components of electronic flight safety systems would have adverse effects on the flight safety of the passengers.
An object of the present invention is therefore to provide a cooling system including a cooling device for cooling components of power electronics installed on board an aircraft, in particular a passenger aircraft which, should a leakage occur in a cooling fluid circuit comprising the cooling device, prevents the components from overheating and therefore guarantees a high level of fail safety of the components.
The above-mentioned object is achieved according to a first aspect of the invention by a cooling system for cooling components of power electronics installed on board an aircraft, in particular a passenger aircraft, comprising a cooling device which is to be coupled in a heat-transmitting and planar manner to the components of the power electronics, and which cooling device comprises at least two heat sinks which are fluidly isolated from one another, the cooling system further comprising at least two cooling circuits each including a cooling fluid source, wherein the at least two heat sinks of the cooling device can be separately supplied with cooling fluids from different cooling fluid sources, and wherein the cooling system is configured such that no phase transition of the cooling fluids within the cooling circuits occurs, during operation of the cooling system.
As the cooling device comprises at least two heat sinks which are fluidly isolated from one another, the two heat sinks can be separately connected to different cooling fluid circuits. However it is also possible for just one heat sink to be connected to a cooling fluid circuit, while the other heat sink is merely brought into thermal contact with a cooling fluid. The second heat sink can therefore continue to guarantee sufficient cooling of the cooling device and therefore of the components of the power electronics if the cooling fluid circuit connected to the first heat sink fails, for example through the occurrence of a leakage.
In one preferred configuration of the invention at least one of the at least two heat sinks is formed as a redundant heat sink in the cooling device. This redundant second heat sink guarantees sufficient cooling of the components in the event of failure of a cooling fluid circuit connected to the first heat sink. The redundancy requires that the arrangement and the cooling capacity of the at least two heat sinks in the cooling device be selected such that just one heat sink (in the case of a total of two heat sinks present in the cooling device) suffices to guarantee sufficient cooling of the components. In a case of this kind the second heat sink takes over the entire cooling of the cooling device.
The heat sinks of the cooling device are preferably formed as a plurality of cooling channels which are adjacent to one another. In the case of a cooling device which comprises a plurality of adjacent cooling channels the cooling efficiency of the cooling device can be increased in the event of failure of a cooling fluid circuit if respective cooling channels which are adjacent to one another are supplied by different cooling fluid circuits. Should a cooling fluid circuit fail, cooling fluid continues to flow through approximately 50% of the cooling channels provided in the cooling device, thereby preventing the components of the power electronics from overheating.
According to one preferred embodiment, the cooling channels in the cooling device extend parallel to one another, at least in sections. Because of the cooling channels extending parallel at least in sections, the cooling device can also uniformly cool the components which are disposed on the cooling device and are to be cooled, at least in regions, to a temperature which guarantees their proper functioning if a cooling fluid circuit fails.
The cooling channels preferably extend in a rectilinear or meandering manner through the cooling device. The meandering path of the cooling channels lengthens the distance between the cooling channel inlet and the cooling channel outlet when compared with a rectilinear path, so that the retention time of the cooling fluid flowing through the cooling device in the cooling channels is increased and the heat transfer from the components to the cooling fluid therefore is maximised.
According to a further configuration of the invention, each cooling channel comprises a cooling fluid inlet and a cooling fluid outlet which are each formed separately from one another. Because each cooling channel comprises a separate cooling fluid inlet and cooling fluid outlet, each cooling channel can easily be connected to a cooling fluid circuit and thus supplied with cooling fluid. This also results in the possibility of providing some of the cooling channels present in the cooling device as redundant cooling channels which increase the fail safety of the cooling device and thus of the components of the power electronics.
The cooling fluid inlets and the cooling fluid outlets are preferably disposed at opposite ends of the cooling device, so that the cooling device can easily be connected via a plurality of cooling fluid circuits to a plurality of cooling fluid sources. The cooling fluid inlets and the cooling fluid outlets can also preferably be disposed at the same end of the cooling device. This makes it easier to fit the cooling device under certain spatial conditions, as the cooling device only has to be accessible from one side for connecting the cooling fluid inlets and the cooling fluid outlets to the cooling fluid sources.
The cooling channels are preferably contained completely in the interior of the cooling device. This results in a homogeneous temperature profile which is virtually symmetrical relative to the longitudinal axis of the cooling device. It is also in particular possible to use liquids to cool the cooling device.
According to a further preferred embodiment of the invention, the cooling device comprises on its outside a plurality of ribs which are provided to air-cool the cooling device. The heat sink provided in the form of the plurality of ribs can therefore air-cool the components of the power electronics by means of the ribs if the entire fluid cooling system fails, which again increases the reliability and fail safety of the cooling device.
The cooling device is preferably formed as an elongate cooling plate. Components of power electronics can thus easily be coupled in a heat-transmitting manner to a face of the cooling plate.
A further aspect of the present invention relates to a method for cooling components of power electronics installed on board an aircraft, in particular a passenger aircraft, in which method a cooling device comprising at least two heat sinks which are fluidly isolated from one another is coupled in a heat-transmitting and planar manner to the components of the power electronics, and in which method the at least two heat sinks are separately supplied with a cooling fluid from different cooling fluid sources associated to different cooling circuits, and in which method no phase transition of the cooling fluid occurs.
According to one preferred embodiment of the method according to the invention, a cooling device is used which comprises a plurality of cooling channels which are fluidly isolated from one another, with adjacent cooling channels of the cooling device being supplied with a pressurised cooling fluid from different cooling fluid sources.
By separately supplying adjacent cooling channels with pressurised cooling fluid, the cooling device can also guarantee sufficient cooling of the components of the power electronics if a cooling fluid circuit of the cooling device fails. The method according to the invention is therefore in particular suitable for cooling the power electronics installed on board a commercial aircraft, as the flight safety is thus considerably increased.
The directions of flow of the cooling fluid in adjacent cooling channels of the cooling device are preferably opposite to one another.
The invention is described by way of example on the basis of preferred embodiments of the invention with reference to the accompanying drawings, in which:
The cooling device 30 is formed as an elongate cooling plate. It comprises a plurality of cooling channels 32, 34, 36, 38, 39 which are fluidly isolated from one another and through which one or a plurality of cooling fluid(s) can flow. In the embodiment which is represented in
Each cooling channel 32, 34, 36, 38, 39 comprises a cooling fluid inlet 32a, 34a, 36a, 38a, 39a and a cooling fluid outlet 32b, 34b, 36b, 38b, 39b which are disposed at opposite ends of the cooling device 30 and formed separately from each other. Therefore, each of the cooling channels 32, 34, 36, 38, 39 provided in the cooling device 30 can be connected separately through the cooling fluid inlets 32a, 34a, 36a, 38a, 39a and the cooling fluid outlets 32b, 34b, 36b, 38b, 39b with a cooling circuit comprising a cooling fluid source, which is not shown.
In the embodiment which is represented in
The components of the power electronics are coupled in a heat-transmitting and planar manner to the top side of the cooling device 30 (as opposed to mounting the components of the power electronics sideways to the top side of the cooling device 30). For example, the s heat transfer from the components to the cooling device 30 can be improved by means of a paste in which metal particles are contained, for example by means of a silver paste.
The cooling channels 46, 48 comprise cooling fluid inlets 46a, 48a as well as cooling fluid outlets 46b, 48b. In the embodiment illustrated in
Through this additionally provided air cooling, the cooling device 30, 40 and therefore the components 10 of the power electronics are maintained at an operating temperature at which overheating of the components of the power electronics is prevented, even if the entire fluid cooling fails. The fail safety of the cooling device according to the invention is additionally increased as a result.
The dimensions of the cooling channels of all the embodiments which are represented in
All the cooling devices are preferably made of a material with a high thermal conductivity, for example, copper, brass, aluminum.
The cooling fluids which are used to cool the cooling devices and therefore to cool the components of the power electronics include liquids and gases as well as two-phase cooling fluids. Water maintained at a low temperature or liquid nitrogen can thus be used as a cooling liquid, for example. However it is also possible to use cooling gases. If gases are routed through the cooling channels of the cooling device according to the invention, the connection points at the inlets and outlets of the cooling device must be appropriately sealed in order to prevent the gases from escaping.
The cooling fluids used to cool the cooling devices are circulated through the respective cooling circuits of the cooling system such that the cooling fluids, as already indicated above, do not undergo a phase transition. Pumps positioned in the respective cooling circuits is are used to maintain an appropriate cooling fluid flow through the cooling system. In order to keep the cooling fluids at a temperature level sufficient for cooling the components of the power electronics, the cooling fluids may flow through a heat sink, such as for example an air-liquid heat exchanger, fluidly connected to the cooling device. In practice, the air-liquid heat exchanger may be positioned inside a ram-air inlet duct so that, during flight of the aircraft, ram-air flows through the heat exchanger which thus cools the cooling liquid. During ground operation of the aircraft where no ram-air is available, a ventilator is used in order to provide for a sufficient air flow through the air-liquid heat exchanger.
Thus, the cooling device on which the components of the power electronics are to be mounted in a heat-transmitting and planar manner (as opposed to mounting the components sideways onto the cooling device) can be connected at its inlet and outlet to the so-called “cooling bus” of the aircraft, in which the cooling fluid (cooling liquid or cooling gas) is already processed to a temperature level sufficient for cooling the components of the power electronics, thereby avoiding the need of the cooling fluid to undergo a phase transition at any point inside the cooling system, as being the case in refrigeration systems, and in which means are provided for maintaining a sufficiently high flow of cooling fluid through the cooling device.
| Number | Date | Country | Kind |
|---|---|---|---|
| DE 102006040187.5 | Aug 2006 | DE | national |
| Number | Date | Country | |
|---|---|---|---|
| 60840625 | Aug 2006 | US |
