The invention relates to an arrangement for cooling arranged in a housing
electrical assemblies, in particular for implementation in base stations
a radio communication system.
an electrically operated technical device leads the power loss of current-carrying components
and assemblies to a heating of the
Since standard electrical components for technical devices only one
limited permissible operating temperature range
for example, up to 70 ° C
These are provided by cooling devices
These cooling devices
For example, fans that are in the housing one of the electrical components
and assemblies circulating or flowing through
build up and thus a discharge
cause the generated power loss or heat.
an operation of technical equipment outside closed rooms or
in adverse circumstances
inside closed rooms
is next to a heat dissipation
a sufficient protection against environmental influences such as dirt particles
provided. Here you have to
Protection regulations complied with the specified IP classes
in order to ensure a permanent function of the technical devices.
From the DE 19755944
It is known to provide in an air inlet of a housing a membrane filter for separating dirt particles and liquids at the surface of the membrane filter from inflowing cooling air. Compared to one example from the DE 19626778
known housing with an air / air heat exchanger, which ensures a complete separation of an internal cooling circuit of an external cooling circuit, by the use of the membrane filter in a simple manner sufficient protection of the electrical components for the above uses of the technical device with the appropriate protective provisions be achieved. At the same time, a temperature difference between the temperature of the ambient atmosphere and the temperature inside the housing required for the cooling is reduced.
Such membrane filter is based for example on a lower
the name Goretex, Sympatex etc. known for use in clothing
Membrane. This membrane consists of a fine mesh or knitted fabric
of fibers, which allows a very small pore size. As a material for this example PTFE
(Polytetrafluoroethylene), also known by the name Teflon.
The membrane is usually on a substrate such as polyamide
or polypropylene realized to a certain stability and resistance
to reach the membrane filter.
the very small pore size of the membrane filter
this is compared to conventional Sun.
mentioned depth filters pollution-resistant, as for example
Dirt particles up to a very small particle size already
on the surface of the
Membrane are deposited and therefore not in the knitted fabric
of the membrane, and
for example, water droplets
Salt crystals. Despite this property, they attach themselves to the surface of the
However, membrane filters degrade and form over time dirt particles
a so-called filter cake, which for the membrane filter flowing through a cooling air
to be overcome resistance
represents. The disadvantage of this filter cake in terms of
a reduction in the cooling air flow rate
due to the increased back pressure and a consequent
the temperature in the interior of the housing impact. Upon reaching
the limit temperature would have
This, for example, the consequence that individual components or assemblies
Self-defense mechanisms activate, which ultimately leads to a shutdown
of the assemblies or even of the technical device. But also one about one
Period existing thermal load of the modules below
the limit temperature leads
for a reduction of the average operating time (MTBF - Mean Time Before
Failure) of the electrical components or assemblies.
to prevent the assemblies or a total failure of the technical device,
the filter used must be cleaned or replaced in good time
become. The period in which a certain degree of blocking
of the filter occurs
but to a great extent
from the quality
the cooling air
from. Thus, a critical blocking of the filter in rural
Areas only after a much longer
Period as for example in urban areas with high
Exhaust emissions or near the sea
occur with a high salt concentration.
For operators of mobile radio systems that set up base stations with such filters in very different environments for supplying radio to subscribers, no or only difficult to predict maintenance intervals for the filter is a high cost factor. Firstly, the comparatively expensive filters should not be replaced or cleaned, if these one more time This can be aggravated by the fact that the base stations are partially installed in hard-to-reach locations, but on the other hand, a failure of a base station and thus the loss of radio coverage of subscribers in a geographical area should be avoided in any case ,
Invention has for its object to provide an arrangement for cooling,
a protection against a failure or an uncontrolled shutdown
ensures electrical assemblies in a housing. This task
is due to the features of the arrangement for cooling and the filter assembly
after the independent
Advantageous developments of the invention are the dependent claims
one in a housing
arranged electrical assembly has at least one in each case
an air inlet of the housing
arranged filter for
at least one filtering of at least dirt particles from inflowing cooling air to
the electrical assembly and at least one cooling device
for building up an air flow
in the case
and to lead out
the filtered, due to a flow and / or flow around the
from at least one air outlet
on. Characteristic is at least one device for determining
a differential pressure value from a respective upstream and downstream of the
Filters certain pressure of the ambient atmosphere, to compare the detected
Differential pressure value with a predetermined differential pressure value,
as well as for outputting a signal when it exceeds or falls below the
provided predetermined differential pressure value.
use according to the invention
a device for determining a differential pressure value uses
advantageous the fact that at an increase in the flow resistance
due to a total or partial blockage of the filter, the cooling device,
for example, a fan,
one with increasing flow resistance
increasing negative pressure in the housing
generated. A differential pressure between the pressure of the ambient atmosphere and the
Pressure inside the case
thus provides a measure of the degree of blocking
of the filter. Should compare the determined differential pressure value
with a predetermined differential pressure value, for example a
ma maximum differential pressure value, exceeding is detected
so will a signal, such as an alarm signal from the device
Embodiments of the invention, the output signal of a
Control device supplied
which is a shutdown of the electrical assembly, a change
the operation of the cooling device
and / or an output of an alarm signal to an associated monitoring device
controls. Physically, the control device can be used both as a
separate as well as one in the facility for determining the
Differential pressure value integrated device be realized.
a shutdown of the electrical components due to the signal
the means for determining the differential pressure value, the
Assembly advantageous from damage or destruction due
become. In the same way, the control of the cooling device,
for example in the form of an increase in the
Speed of the fan
or connecting a further fan overheating in the housing advantageous
prevent. The output of an alarm signal is particularly for the application
in centrally monitored
Systems advantageous. Thus, in the case of an introductory described
Radio communication system from the affected base station an alarm signal,
optionally together with further status or alarm signals,
transmitted to a central operating and maintenance center
become. Starting from this operation and maintenance center
Maintenance personnel with the replacement or cleaning of the filter
entrusted and if necessary the base station switched off or in
limited in scope.
Device for determining the differential pressure value exists
a further embodiment of the invention of at least two pressure sensors,
and inside the case
are arranged, and an evaluation, which from the of
the pressure sensors determined absolute pressures of the ambient atmospheres a
Differential pressure calculated.
Pressure sensors can
commercial pressure sensors,
for example, the company Honeywell, type Precision Pressure Transducer
PPT, which uses the measured pressure in a corresponding
implement analog or digital signal.
In an alternative embodiment, the device for determining the differential pressure value may be designed as a differential pressure sensor. This consists according to the prior art, for example, two hermetically separated by a membrane measuring chambers, the deflection of the membrane is a measure of the size of the differential pressure. In differential pressure sensors can advantageously additionally a comparison of the determined differential pressure with predetermined Grenzwer and corresponding signals are output when these limit values are exceeded.
Differential pressure sensor can be particularly advantageous directly in a
the filter enclosing frame
be integrated, each one of the two measuring chamber before
and behind the filter determines the current absolute pressure of the ambient atmosphere.
According to one
Another embodiment is in each case an averaged differential pressure value
compared with the predetermined differential pressure value, wherein the averaging over a
Number of measurements. Advantageously, this short-term fluctuations
the pressure that occurs, for example due to gusts of wind
balanced and thus the safety in determining the degree of blocking
of the filter increases.
As an alternative to an averaging, for example, in the same way
Extreme values or statistics about
measured differential pressures
evaluated according to fixed algorithms.
The invention further comprises a filter arrangement consisting of a
Filter and a frame enclosing the filter, in or
in addition to the frame
a device described above for determining a differential pressure value
is arranged. This filter arrangement is particularly suitable for a
Use in housings
of technical devices
with electrical components. Such technical devices are
For example, base stations of radio communication systems, traffic guidance devices,
Supply devices or control cabinets for industrial control
Machinery. In the same way, the arrangement according to the invention
a use in smaller electrical devices, such as portable
Home computers or in electrical measuring devices, suitable.
The invention will be explained in more detail with reference to the accompanying drawings.
1 a base station of a mobile radio system with the arrangement according to the invention for cooling electrical components in a side view,
2 a base station of a mobile radio system with the arrangement according to the invention for cooling electrical components in an alternative embodiment,
3 Components of a radio communication system, and
4 a flow diagram of a method according to the invention.
A technical device, for example a base station BTS of a radio communication system or mobile radio system, according to 1 has one or more electrical assemblies BG. These can be, for example, so-called TRX modules (transceivers) as well as other modules for baseband signal processing and communication with other components of the system. Here is an example of the configuration of base stations of the type BS-41, BS-241 or NB-441 Siemens AG pointed. According to a known type, the assemblies BG consist for example of plug-in housings with electronic components and high-power circuits located therein. Subassemblies BG are understood within the scope of the invention, all electrical devices of a technical device. For example, printed circuit boards realized in a personal computer and peripherals such as hard disks can be counted for this purpose.
Operation of the base station BTS leads
the power loss of the individual electrical assemblies BG too
whereby the need for cooling arises to a maximum
Operating temperature of the assemblies BG or individual electrical
Components not to exceed.
in a side view or review shown housing G a
Base station BTS or generally an electrical device has
on an end face an air inlet LE with a arranged therein
Membrane filter MB on. The dimensions
of the air inlet LE are dimensioned such that through the membrane filter
MB one for cooling
the electrical assemblies sufficient amount of cooling air from the ambient atmosphere of the base station BTS
in the case
G, even with a partial addition of the membrane filter MB through
Dirt particles or liquid,
can. To protect the membrane filter MB from mechanical damage as well
direct exposure to splashing water
Lamellae LAM are provided.
The membrane filter MB is designed as a surface filter, which has the particularly advantageous property of already depositing dirt particles and liquids of the ambient atmosphere on the surface of the membrane, whereby, for example, sensitive electronic components or circuits in the assemblies BG are protected against environmental influences. Such a membrane filter MB is based for example on an under the name Goretex, Sympatex etc. for use in clothing known membrane, but which is adapted to the specific requirements of an application in technical equipment, for example, in terms of pore size or fire resistance. The membrane of the filter consists of a fine mesh or knitted fabric of fibers. A very small pore size prevents penetration of the dirt particles and thus irreversible clogging of the membrane. Nevertheless, dirt particles can deposit on the surface of the membrane to form a filter cake. Likewise, liquids up to a specific pressure per unit area can not pass through the membrane. The material used for the membrane, for example, PTFE, also known under the name Teflon. The membrane is usually applied to a coarsely woven carrier material such as polyamide or polypropylene in order to achieve high stability and resistance of the membrane filter MB.
a special design of the membrane filter MB can protect against
IP policies are met until, for example, IP55, which makes a deployment
of the technical device
or under adverse environmental conditions, such as
in industrial production occurs. By a special
Selection of the membrane filter material can also be an individual
Adaptation to real environmental conditions, such as a
Resistance to acids,
However, embodiments described below are not on
the use of membrane filters in the technical device or the
Base station limited.
Other known filters, such as conventional depth filters for filtering
Dirt particles, or filters made of hydrophobic material with one
Membrane filter comparable properties for filtering dirt particles
are used in the same way in the inventive arrangement in the same way.
The in the 1 shown electrical assemblies BG are arranged one above the other in the housing. Through the membrane filter MB inflowing cooling air - represented by arrows - is guided in an inflow KE and an air guide LLE under the electrical components BG. The louver LLE, for example, an air baffle, thereby has the task to distribute the cooling air evenly over the base of the lowest electrical assembly BG, so it comes to a homogeneous flow through the entire assembly BG. The cooling air flows through the plug-in housings or assemblies BG provided with ventilation slots and dissipates heat from the electrical components and circuits.
the electrical components BG by means of a direct flow through the
G with cooling air
has the advantage of being required to approach zero
Temperature difference between the temperature of the ambient atmosphere or
the temperature of the incoming
and the temperature inside the housing G, reducing the operation
the electrical assemblies BG even at a temperature of the ambient atmosphere of, for example
+ 70 ° C, the
the limit temperature of the components corresponds, reduced by the
Degree of internal warming,
A cooling arrangement VE, which in the 1 is arranged, for example, above the uppermost assembly BG sucks in the flow of the assemblies BG heated cooling air and leads them via an outflow KA and provided on the back of the housing G air outlet LA to the ambient atmosphere. The air outlet LA is again protected by lamellas and optionally a - not shown - membrane filter from mechanical damage and ingress of spray water. As cooling devices VE, for example, one or more fans are used, the temperature-controlled generate a varying air flow.
Control of the temperature inside the housing G is the speed of the
Fan controlled by a control device ST. To capture
this regulation can
for example in the area of the air inlet LE, the air outlet
LA and at various locations within the housing G temperature sensor provided
which are permanently the temperatures of the incoming cooling air and
inside the case
G or determine the temperature of special components, and
which are evaluated by the control device ST. At this
Regulation is governed by the speed of the fan of the cooling device
VE is the flow rate of the cooling air
in the case
G varies, for example, a constant temperature inside
of the housing
from the temperature of the ambient atmosphere.
A constant operating temperature of the assemblies BG, for example, has a positive effect on the service life of electrical components and high-performance circuits. In addition, an always kept low speed of the cooling device VE, under the condition that the limit temperature of the components is not exceeded, allows a minimization of the noise emission of the technical device. Furthermore, by the control at a cold start of the device initially from Be operation of the cooling device VE be omitted to allow the assemblies BG to heat quickly to the desired operating temperature and only after reaching this operating temperature to perform a further control of the cooling device VE to maintain the constant operating temperature.
a certain restriction
the cooling air flow rate
through the membrane filter MB, for example due to the foregoing
described themselves on the surface
forming filter cake or deposits of dirt particles,
the cooling device
For example, a larger amount
Cooling air over the
Air outlet LA from the housing
G out as can flow through the air inlet LE in the housing G,
to compensate for the partial blocking of the membrane filter MB and
a constant cooling air flow
sure. This creates a negative pressure in the housing G.
In the example of 1 is measured by two commercially available pressure sensors S1, S2, for example of the type Honeywell PPT, in each case an absolute pressure inside and outside of the housing G. For this purpose, the first pressure sensor s1 can be attached, for example, anywhere on the outside of the housing, but here too protection of the sensor against mechanical damage and other environmental influences, which can restrict the functioning of the sensor, makes sense. The second pressure sensor S2 is disposed within the housing G, for example, as shown near the back of the membrane filter MB. However, the second pressure sensor S2 can be arranged in the same way anywhere in the housing G, since there is usually a constant absolute pressure in the housing G.
The absolute pressures of the ambient atmospheres outside and inside the housing measured by the pressure sensors S1, S2 or the digital or analog signals derived from these pressure measurements in the sensors are compared with one another in an evaluation device AE in order to determine a differential pressure value. From a comparison of the determined differential pressure value with a predetermined limit value, when the limit value is exceeded, a signal is generated which is forwarded by the evaluation device AE to a central control device ST of the base station BTS. The underlying method is referring to 4 explained in detail below.
Control device ST, which also includes other functionalities
Base station BTS such as the function of the power amplifier, the power supply
or otherwise supervised,
in turn, due to the signal of the evaluation device AE
Alarm signal to an operating unit assigned to the base station BTS
and maintenance center OMC. Starting from the operations and maintenance center
maintenance or replacement of the membrane filter MB is initiated
and optionally functions of the base station BTS, for example
switching off TRX modules to reduce the generated ones
adapted to the conditions. The signaling of the requirement
the maintenance of the membrane filter has the advantage that on the one hand
extends the maintenance intervals
and on the other hand, the operating cost of the base station due
a mode of operation kept in an optimum temperature range
or the risk of the occurrence of interference can be reduced.
In addition to the described implementation with separately arranged sensors S1, S2 and evaluation AE, the functionality can also be realized in a single device. This is exemplary in 2 shown. In this alternative embodiment, a commercial differential pressure sensor DD is used. A differential pressure sensor usually consists of two hermetically separated by a membrane measuring chambers, the deflection of the membrane is a measure of the size of the differential pressure.
the differential pressure sensor DD is carried out according to the previous one
Description a comparison of the determined differential pressure with
at least one predetermined limit and outputting corresponding ones
Signals when exceeded
this limit value to the control device ST.
After 2 the differential pressure sensor DD is integrated into a frame R enclosing the membrane filter MB, wherein one of the two measuring chambers can perform measurements upstream or downstream of the membrane filter MB with respect to the respective actual absolute pressure of the ambient atmosphere via an opening in the frame R.
The active surface of the membrane filter MB is in the example of 2 increased by a wrinkling and thereby takes laterally a larger volume. At the same time, however, the stability of the filter and the cooling air flow rate is increased. The arrangement of the membrane filter MB in a frame R allows rapid removal of the membrane filter cassette consisting of the membrane filter and the frame for maintenance and cleaning purposes or for replacement.
In the 3 are exemplary components of a known GSM (Global System for Mobile Communication) or UMTS mobile radio system (Universal Mobile Telecommunication System) shown. A mobile radio system consists of a number of switching centers MSC (Mobile Switching Center), which ensure a transition to public telecommunications networks PSTN (Public Switched Telephone Network) and packet data networks, such as the Internet. The switching devices MSC each have a plurality of base station systems BSS (Base Station System), consisting of base station controllers BSC (Base Station Controller) and base stations BTS (Base Transceiver Station), respectively. The base stations BTS a geographical area, also called radio cell Z, with radio resources. On the radio interface between the base stations BTS and user equipment UE (User Equipment) signals in uplink UL (uplink) and downlink DL (downlink) are transmitted.
is particularly advantageous in outside closed rooms set up
Base stations BTS of such a mobile radio system used.
Such base stations are also referred to as outdoor base stations.
connected to a switching device MSC is still such
called Operations and Maintenance Center OMC (Operation and Maintenance
Center). In this run information about the status of the individual components
of the system so that from a central point of the system
monitors the functionality
can be. To this operation and maintenance center would after
the invention sent an alarm signal from the base station BTS
if it were found that
an exchange or a cleaning of the membrane filter MB in the base station
BTS is required. As a result of this alarm could, for example, for maintenance
the maintenance staff responsible for the filter to the base station
be sent. As described above, can in the same way
in response to the alarm signal, the functionality of the base station
on the part of the Operations and Maintenance Center OMC, for example
by switching off one or more modules,
to avoid the assemblies. Alternatively or additionally, the monitoring or control device leads
in the base station automatically
switching off modules, and informs the operator
and maintenance center using known signaling accordingly.
In 4 Finally, a flowchart is shown, the individual steps in the device according to the invention, for example in a differential pressure sensor described above, are performed.
In a first step, absolute pressures d1, d2 of the ambient atmosphere outside and
inside the case
upstream and downstream
of the filter. The measurements take place, for example, periodically
at certain intervals.
From these measurements d1, d2 or these representing digital or analog
Values, a pressure difference value dd is calculated in a second step.
Alternatively to these two steps, according to the preceding
described way also directly differential pressure readings in one
Be taken up step.
short-term pressure fluctuations and thus possibly triggered false alarms
to avoid, an evaluation of the determined differential pressure values
Thus, in a third step, for example, over a number n of calculated
Pressure difference values dd an averaging are made, from which the amount
a mean pressure difference value mdd is determined. The averaging
may be running, e.g. considering
a respective number of last calculated values, so that
with each measurement a new average is determined.
a fourth step is a comparison of the average pressure difference value
mdd with a limit value or a maximum differential pressure value
For example, the limit ddmax may depend on the configuration of the
Base station and / or site, taking into account environmental conditions,
dimensioned and stored in the device. Is in
This comparison found that the averaged pressure difference value
mdd greater than
is the maximum pressure difference value ddmax, so is the pressure difference sensor
DD or the control device ST of the base station in a fifth step
an alarm signal al issued. Unless the comparison shows that
the maximum pressure difference value ddmax from the averaged pressure difference value
In the following, further measurements, calculations and comparisons will be made
performed according to the steps described.
can do this
in the same way extreme values of the differential pressures or in general statistics over the
measured differential pressures
according to defined algorithms with a given alarm criterion
be compared. This can be done for example in such a way that
the measured differential pressure values over a period of approx.
one hour are evaluated, and an alarm signal only then output
if all the differential pressure values determined in this period are
do not exceed a limit.