Electricity: electrical systems and devices – Housing or mounting assemblies with diverse electrical... – For electronic systems and devices
Reexamination Certificate
2001-10-09
2003-04-22
Thompson, Gregory (Department: 2835)
Electricity: electrical systems and devices
Housing or mounting assemblies with diverse electrical...
For electronic systems and devices
C055S385400, C055S385700, C174S034000, C174S034000, C361S818000, C454S184000, C428S045000, C428S304400
Reexamination Certificate
active
06552900
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to an apparatus for cooling an electrical module arranged in a housing and, in particular, a base station of a mobile radio system or wireless subscriber line system.
In an electrically operated technical appliance, the lost power of components and modules through which current flows leads to a heating-up of the appliance. Since standard electrical components for technical appliances have only a limited admissible operating temperature range of, for example, up to 70° C., they are cooled by cooling devices. These cooling devices are, for example, fans which establish an air flow in the housing, flowing around or through the electrical components and modules, and which consequently bring about a discharge of the thermal output produced.
During operation of the technical appliances outside enclosed spaces or in adverse conditions within enclosed spaces, adequate protection from environmental influences, such as, for example, dirt particles and liquids, must be additionally provided along with heat discharge. In this respect, protective regulations in accordance with the specified IP classes must be observed in order to ensure longterm functioning of the technical appliances.
It is known from DE 19755944 to provide in an air inlet of a housing a membrane filter for a superficial filtering of dirt particles from inflowing cooling air and for separating out liquids. In comparison with a housing known, for example, from DE 19626778, with an air/air heat exchanger, which ensures complete separation of an internal cooling circuit from an external cooling circuit, adequate protection of the electrical components can be achieved for the aforementioned areas of use of the technical appliance with the corresponding protective regulations in a simple way by use of the membrane filter. At the same time, a temperature difference, required for the cooling, between the temperature of the ambient atmosphere and the temperature inside the housing is reduced.
A membrane filter of this type is based, for example, on a membrane filter known for use in articles of clothing by the designation Goretex, Sympatex, etc. The membrane of the filter includes a fine netting or knitted fabric of fibers, which permits a very small pore size. An example of a material which may be used for this is PTFE (polytetrafluoroethylene), also known by the name Teflon. The membrane is generally provided on a backing material, such as, for example, polyamide, in order to achieve a certain stability and resistance of the membrane filter.
In addition to the criteria with regard to protective regulations, EMC guidelines (EMC—Electromagnetic Compatibility) also must be satisfied, ensuring on the one hand protection of the electrical modules arranged in the housing of the technical appliance from electromagnetic influences from the surroundings of the appliance and, on the other hand, protection of the surroundings from electromagnetic radiation emanating from the electrical modules.
On account of the plastic material used, the membrane filter is permeable to electromagnetic radiation and consequently does not bring about adequate shielding. Additional shielding, for example by a wire netting arranged in front of the membrane filter, is therefore necessary to satisfy the EMC guidelines. However, it is disadvantageous to provide this additional wire netting as a further element of the housing of the technical appliance and, for example, it increases the overall dimensions of the housing. Furthermore, it makes maintenance and cleaning of the membrane filter more difficult.
U.S. Pat. No. 5,431,974 discloses a filter arrangement for electromagnetic shielding. The filter arrangement in this case includes an electrically conductive frame with at least one opening, a panel of porous electrically conductive material, a layer of electrically conductive adhesive and an electrically conductive gasket material. Preferably chosen as the porous panel is a synthetic polymer which has been made electrically conductive at the surface by electrochemical processes.
The present invention, therefore, is directed toward specifying an apparatus for cooling which, with known use of a membrane filter, permits adequate electromagnetic shielding without the specified disadvantages of the prior art.
SUMMARY OF THE INVENTION
The apparatus according to the present invention for cooling an electrical module arranged in a housing has at least one membrane filter, arranged in an air inlet of the housing in each case, for a superficial filtering of at least dirt particles from inflowing cooling air for cooling the electrical module and also at least one cooling device for establishing an air flow in the housing and for discharging the filtered cooling air, heated up from flowing through or around the module, out of the housing from at least one air outlet. The membrane filter is characterized by having a netting of an electrically conductive material for electromagnetically shielding the electrical module.
The configuration of the apparatus according to the present invention has the advantage that an integration of the electrically conductive netting achieves the effect of electromagnetic shielding without an additional shielding arrangement having to be provided. Furthermore, the advantageous properties of the membrane filter are not restricted. For example, simple cleaning of the filter without prior detachment of a shielding grating is possible. As a result, the housing of the technical appliance can be provided in a very compact form.
The apparatus according to the present invention can be used in technical appliances with at least one electrical module, such as, for example, base stations of a mobile radio system or wireless subscriber line system (access network systems), traffic control devices, power supply devices or switch cabinets for a control system of industrial machines. In the same way, the apparatus according to the present invention can be used, for example, in smaller electrical appliances, such as a portable or stationary home computer, or in electrical measuring instruments.
According to a first embodiment of the present invention, the membrane filter additionally separates out liquids at the surface, whereby use of the technical appliance is also possible outside enclosed spaces or under adverse ambient conditions.
According to a second embodiment, the membrane filter is provided in the form of a fine-pored membrane applied to a backing material. This configuration of the membrane filter advantageously permits individual adaptability of the backing material and/or the membrane to special conditions of use of the technical appliance. For example, a filter resistant to chemical substances, such as acids, can be used for technical appliances used in production.
According to a third embodiment, based on the second embodiment, the electrically conductive netting is woven into the backing material of the membrane filter. As a result, a firm bonding of the netting to the backing material is advantageously achieved, one of the effects being, for example, that the stability of the membrane filter is increased.
As an alternative to the third embodiment, the electrically conductive netting is applied to the backing material. This embodiment advantageously permits simple production of the membrane filter, the electrically conductive netting being applied to the membrane filter, for example, in an additional production step. A bonding between the netting and the backing material can be achieved, for example, by an adhesive bonding technique.
According to a further alternative embodiment, the electrically conductive netting is provided in the form of backing material for the membrane. By this embodiment, the electromagnetic shielding is advantageously integrated directly into the membrane filter, as a result of which there are no further working steps in the production of the membrane filter.
According to further alternative embodiments, the membrane may be made from a PTFE material known as Tef
Hoefer Bruno
Reeck Guido
Bell Boyd & Lloyd LLC
Siemens Aktiengesellschaft
Thompson Gregory
LandOfFree
Device for cooling an electric module and a technical appliance does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Device for cooling an electric module and a technical appliance, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Device for cooling an electric module and a technical appliance will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3101038