Rail vehicle having an air-conditioning system provided
for cooling electrical devices and method for cooling
the electrical devices in the rail vehicle
Description:
The present invention relates to a rail vehicle having
an air-conditioning system for cooling, by means of
cooled air, electrical devices located in the machine
room of the rail vehicle, and to a method for cooling
the electrical devices.
Such electrical devices are auxiliary equipment which
does not serve directly to drive the vehicle, for
example a compressed-air-generating device, fire-
extinguishing devices, train protection devices,
electronic devices with electronic and/or micro-
electronic devices for controlling the operation of the
vehicle, electrical supply devices for further wagons
which are connected to the vehicle, and cooling devices
for the abovementioned devices. The specified
components can accordingly be cooling units, open-loop
and closed-loop control units and drive components, and
further electrical and electronic components. The
specified electrical devices are typically located in a
machine room of the rail vehicle which is separated
from one or more driver's cabs.
The specified electrical devices generate heat during
operation and must therefore be cooled. Otherwise,
their service life is limited and their failure rate
increases.
In order to fulfil this objective, for example German
Patent no. 853 463 discloses an electrical locomotive
whose control devices for the main and auxiliary power
circuits are accommodated in a cabinet which can be
removed in an upward direction and is provided with

doors. In the centre, the cabinet has a vertical
ventilation chimney which has a plurality of
electrically driven fans with a vertical axis at the
top, and resistors which are to be cooled at the
bottom. The fan is open towards the floor and towards
the roof of the locomotive, with the result that an
airstream which is favourable for cooling is produced.
EP 0 625 456 Bl also describes a device for ventilating
at least one traction motor and/or a cooling device of
a rail tractive unit. Auxiliary units, for example
power converter systems and electronic switchgear
cabinets and a compressor liquidizer unit are cooled
with the cooling device. For this purpose, vertical air
ducts are provided through which a flow is forced by
means of a ventilator. The air ducts are assigned to
the traction motor and/or to the cooling device. The
air which is used for cooling is sucked in via the roof
of the rail tractive unit and discharged in a downward
direction.
In addition, DE 10 2006 043 110 Al discloses an
electrical locomotive having an internal combustion
engine, an electrical generator, an inverter and at
least one drive motor. A first and a second cooling
element, which are together part of a common cooling
unit, serve to cool the internal combustion engine and
the inverter. The cooling unit is mounted on the floor-
side longitudinal beams of the locomotive and sucks in
air for the cooling from below.
Finally, EP 2 127 991 Al describes a locomotive which
has two driver's cabs and a machine room. In order to
cool the machine room and at least one driver's cab, at
least one cooling assembly and a duct-shaped line
system for conducting an airstream cooled by the
cooling assembly are provided. The line system permits
the cooled air to be conducted through openings in such

a way that the cooled air impacts in a targeted fashion
on components to be cooled, or into cabinets with
components to be cooled. The locomotive has two
driver's cabs which are unoccupied or occupied
depending on the direction of travel. An air-
conditioning unit is arranged in each of the two
driver's cabs. The air-conditioning unit of the
unoccupied driver's cab is provided for cooling the
machine room, while at the same time the air-
conditioning unit of the occupied driver's cab is used
exclusively for air-conditioning the occupied driver's
cab.
The concepts described above for the ventilation, air-
conditioning and cooling of. the components in the
vehicle which heat up are suitable for maintaining a
sufficiently low temperature so that the prescribed
upper temperature limit of these components is not
exceeded. However, it has been found that the fail-
safety of the electrical components cannot be optimized
in a satisfactory way despite these measures, with the
result that further measures have to be taken to ensure
the necessary readiness to provide transportation
services.
This problem is solved by means of the rail vehicle
according to Patent Claim 1 and by means of the method
for cooling electrical devices of the rail vehicle
according to Patent Claim 12. Preferred embodiments of
the invention are specified in the sub claims.
The rail vehicle according to the invention may be a
rail tractive unit, for example a locomotive, a
tractive unit or power unit for a rail vehicle block
train, in particular, a tractive unit or a power unit
for heavy rail vehicles and block trains, for example
for long-distance trains, goods trains and regional
trains.

The rail vehicle according to the invention comprises a
machine room for accommodating electrical devices which
are necessary, in particular, for operating the rail
vehicle, as well as at least one driver's cab. The rail
vehicle also comprises an air-conditioning system for
the machine room, which is provided for generating
cooled air serving to cool the electrical devices.
Excess heat from the machine room is carried away with
this air-conditioning system. The cooled air generated
by the air-conditioning system is conducted in an
inventive way in an air circulation which circulates
exclusively inside a space which is to be air-
conditioned in the machine room. The electrical devices
to be air-conditioned are located in this space. This
means that additional air is not fed from the outside
to the stream of cooled air which circulates in this
space in the machine room, nor is a part of said stream
of cooled air branched off and conducted to the
outside. Accordingly, the air flow inside the specified
space is conducted completely independently and
separately from the air located outside the air-
conditioned space.
A method for cooling at least one electrical device in
a machine room of a rail vehicle is therefore also
essential to the invention. This method comprises the
following method steps:
• . the generation of cooled air by means of an air-
conditioning system which the rail vehicle
comprises, and
• conducting of the cooled air in an air circulation
which circulates exclusively inside an area which
is to be air-conditioned in the machine room.
It has, in fact, become apparent that feeding fresh air
for cooling the components which heat up leads to

considerable contamination of the components, with the
result that they are no longer reliably fail-safe. This
is because "through-ventilation" of the machine room
with external air which although filtered nevertheless
is loaded with very fine particles of dust leads to the
specified problems. The provision of filter means for
cleaning the fed-in air is, according to the inventors'
realizations, not sufficient either to ensure the
necessary purity of the air located in the machine
room. Although a certain degree of improvement could,
in theory, be achieved by conducting air in a targeted
fashion from a machine room fan (blower) to the
critical areas of the sensitive electrical devices in
the .racks, the basic problems of loading both with a
high temperature and with dust are not solved.
Furthermore, it has also become apparent that fresh air
can introduce moisture into the machine room, which
adversely affects the electrical devices. It is
disadvantageous to air-condition the entire machine
room since this would require a very large powerful
air-conditioning system with a correspondingly large
power requirement and air throughput rate. It would
also be impossible to solve the latter problem through
thermal insulation of the vehicle since a machine room
of a rail vehicle cannot be effectively insulated
because the installed racks largely take up the
available space inside the vehicle. Ultimately, the
roof of the vehicle is not available for the
installation of such a powerful air-conditioning system
since the roof is generally occupied with numerous
components.
Only by separating the air flow circulating within the
space to be air-conditioned from the contaminated air
which is located outside is sufficient operational
reliability of the components in the machine room
possible. In particular, dust-loaded air whose
particles can easily even penetrate filters and/or

moist air can lead, in particular given relatively
lasting exposure, to considerable contamination of the
components and adverse effects thereon, and to the
failure of sensitive equipment.
An essential aspect of the present invention therefore
comprises avoiding the feeding in of external air by
virtue of the fact that at least one closed (air)
circulation is provided in a largely sealed machine
room. This also includes ensuring that the machine room
is separated from the driver's cabs in terms of air.
With the inventive concept it is possible to air-
condition all the sensitive electrical devices, i.e.
the secondary equipment, for example the electrical
auxiliary equipment specified at the beginning
(compressed-air-generating device, fire-extinguishing
devices, train protection devices, electronic devices
with electronic and/or micro-electronic devices for
controlling the operation of the vehicle, electrical
supply devices for further wagons which are connected
to the vehicle, cooling devices for the above-mentioned
devices) i.e. to keep said devices below a predefined
maximum temperature limit. In addition, the air-
conditioning of the machine room which is implemented
in the inventive way can be used not only in the case
of electrical rail vehicles, i.e. rail vehicles which
are supplied with electrical energy from the outside,
but also in the case of rail vehicles which are
equipped with an internal combustion engine. In the
latter case, the internal combustion engine can serve,
in particular, for driving an electrical generator
which in turn generates current for an inverter, and
the inverter converts the current and feeds the drive
motor or drive motors.
In one preferred embodiment of the invention, the
cooled air is directed in a targeted fashion to the

electrical devices by means of air-conducting means.
While, of course, conducting the flow of cooled air in
the machine room in an untargeted way already brings
about a considerable improvement in the fail-safety,
since in this way the temperature of the individual
components can be kept below a predefined limit,
conducting the cooled air to the electrical devices in
a targeted fashion is advantageous since much more
effective cooling of these components can be achieved
in this way. This is because the targeted flow against
said components permits heat to be carried away more
efficiently, with the result that, if appropriate, the
components can also be operated with a relatively high
specific power loading. Under certain circumstances it
is possible to use components which are configured for
a relatively high power loading, which in turn makes a
relatively small design possible, with the advantage of
a saving in space.
For example, the cooled air can be blown against the
sensitive components and equipment via nozzles. An even
more effective method of bringing about a target flow
against the electrical devices is to provide air ducts
in which the cooled air is directed in a targeted
fashion to the electrical devices. For example, the
electrical devices are accommodated in one or more
housings or racks, with the result that the cooled air
can be directed into these housings or racks. If
appropriate, an air duct in which the cooled air is
conducted as far as the direct vicinity of the
electrical device, i.e. the distance between the
opening of the air duct which lets out the cooled air
and the electrical device is very small, for example
less than 50 cm, preferably less than 20 cm, and quite
particularly preferably less than 10 or even 2 cm. In
this case, the air is blown out of the air duct in the
direct vicinity of the electrical device. The
electrical device which is to be cooled is quite

particularly preferably located inside a housing or
rack which itself has the cooled air flowing through
it.
At least one air-treatment device, which is connected
to the air ducts, is preferably present. Air is cooled
in the air-treatment devices and then directed to the
electrical devices via the air ducts. For example, such
an air-treatment device comprises one or more cooling
elements for the air and one or more fans in order to
generate a flow of cooled air which is directed into
the air ducts.
A further essential aspect of the present invention
therefore consists in limiting the cooling by air-
conditioned air to the sensitive components in the
various racks.
In a further preferred embodiment of the invention,
after contact with the electrical devices, the cooled
air passes through the free interior space of the
machine room to the at least one air-treatment device.
In the present description and in the patent claims,
the free interior space of the machine room is
understood to be those areas of the machine room which
are not taken up by an electrical device or some other
device which is directly or indirectly required for
operation of the vehicle, or other installations, also
in particular by an air duct. In the free interior
space of the machine room, an air flow is therefore not
directed (conducted) but rather circulates freely and
without external influence or deflection. In this
embodiment, the cooled air therefore initially
preferably passes in a targeted fashion, for example
through a duct system, to the electrical devices and
cools them. The air is then blown out into the machine
room. The air circulation which is produced in this way

brings about a certain degree of cooling and through-
ventilation of the entire machine room.
In a further preferred embodiment of the invention, the
at least one air-treatment device comprises filter
means for the cooled air. Although the air circulation
which circulates exclusively inside the space to be
air-conditioned in the machine room already ensures
that no additional contamination can be fed into the
machine room, contamination which is already present
can be removed in a targeted fashion with additional
filtering, with the result that even further improved
fail-safety of electrical devices can be achieved. A
commercially available dust filter can be used for this
purpose.
In a further preferred embodiment of the invention, the
air-conditioning system also comprises at least one
refrigeration machine for cooling the air. Such
refrigeration machines are known and typically comprise
at least one vaporizer, at least one compressor, at
least one condenser and at least one expansion valve in
at least one circuit for a refrigerant. The at least
one vaporizer serves to absorb heat from the
surroundings into the refrigerant. Inter alia, the
quantity of heat which is taken up is discharged again
from the coolant in the at least one condenser. The at
least one vaporizer therefore serves as a heat sink and
therefore as a cooling element for cooling the air.
When a refrigeration machine is used in the rail
vehicle according to the invention, the at least one
vaporizer is therefore preferably integrated into the
air-treatment device in order to act there as a cooling
element for the air to be cooled. The at least one
refrigeration machine therefore comprises in each case
at least one vaporizer for cooling the air, wherein the
at least one vaporizer is in each case a component of
an air-treatment device of the air-conditioning system,

in which air-treatment device the cooled air is
generated.
The vaporizer or vaporizers can be installed upstream
or downstream of the abovementioned additional filter
in the direction of flow of the air used for air-
conditioning.
When the vaporizer is installed downstream of the
filter, particularly pure filtered air can be directed
through the vaporizer or vaporizers, with the result
that the risk of contamination of vaporizer or
vaporizers is also reduced.
The air-treatment device can be arranged, in
particular, inside the machine room. Alternatively, it
can also be mounted outside the machine room, in
particular outside the rail vehicle, for example on the
roof, or, less preferred, under the floor of the rail
vehicle. Of course, an arrangement in the machine room
is preferred since this provides encapsulation against
heat and contamination entering from the outside.
Furthermore, there is no need for additional space to
be taken up for this device inside the vehicle profile
which is predefined by a rail operator.
Both the air-treatment device and the air ducts for
conducting the cooled air can be insulated from the
outside thermally and/or against sound emissions.
Customary sound-damping materials can be used for this.
Although the air-treatment device is sealed against the
ingress or exiting of air to the outside, the air-
treatment device is in contact with the surroundings
for the operation of one or more cooling elements. If a
refrigeration machine is used for the operation of a
cooling element and if the cooling element in the air-
treatment device is therefore a vaporizer, the

vaporizer is connected to one or more condensers of the
refrigeration machine outside the air-treatment device
via pipelines in which a refrigerant is conducted in
the circuit. The condenser or condensers serve(s) to
discharge again the heat which has been taken up by the
refrigerant in the vaporizer. For this purpose, a
suitable heat reservoir must be available. This may be,
for example, the external air. For this reason, the
condenser or condensers is/are preferably integrated
into a further air circulation which comprises sucking
in external air, contact with the sucked-in external
air for the purpose of the exchange of heat with the
condenser or condensers, and the discharging of the
heated air to the outside again. The condenser or
condensers can, of course, be mounted on the rail
vehicle in such a way that the slip stream flows
against them. However, one preferred variant consists
in accommodating the condenser or condensers adjacent
to at least one opening in the external wall of the
vehicle and quite particularly preferably adjacent to
at least one opening in the external wall of the
machine room and bringing about a flow of sucked-in air
around and/or through the latter by means of at least
one fan. After the contact between the external air and
the condenser or condensers, the heated air can be
directed to the outside again. The compartment in which
the at least one condenser and, if appropriate, the
compressor or compressors and the at least one fan are
located is separated from the air-treatment device,
with the result that no mixing of the air can take
place. Furthermore, it is preferred if the component
which contains the at least one condenser, the at least
one compressor and the at least one fan is thermally
insulated from the air-treatment device.
A cleaner machine room is therefore ensured through two
independent air circulations. On the one hand, through
an external circulation which ensures that the heat

generated is transported away to the outside and for
this purpose the flow of external air from the outside
is caused to flow around and/or through the condenser
or condensers of the refrigeration machine, and in
which the heated air is then directed to the outside
again, and on the other hand by means of an internal
circulation which is limited exclusively to the space
to be air-conditioned in the machine room and in which
air is preferably sucked in from this space and is
directed to the electrical devices (in the housings and
racks) after the cooling process.
Instead of a refrigeration machine comprising a
vaporizer, compressor, condenser and expansion valve,
it is also possible to use a thermo-electrical cooling
element or even some other cooling element.
An air-treatment device can be combined with one or
more condensers, preferably with the condensers of the
same refrigeration machine which are associated with
the vaporizer or vaporizers of the air-treatment
device, the compressor or compressors and fans to form
one structural unit which can be referred to as an air-
conditioning device.
If at least one refrigeration machine is used to cool
the air circulating in the machine room, said
refrigeration machine is dimensioned in a first
invention variant for exclusively cooling the machine
room, i.e. the refrigeration machine is configured in
terms of the cooling capacity in such a way that it is
sufficient for sufficient cooling of the air
circulating in the machine room, i.e. of the sensitive
electrical and electronic components which are arranged
there and are to be cooled, but cannot additionally
ensure additional cooling of the driver's cab or cabs.
The dimensioning of the overall cooling capacity of the
at least one refrigeration machine depends, of course,

on the generation of heat by the electrical devices in
the machine room and on the exchanging of heat between
the rail vehicle and its surroundings.
In one alternative invention variant, in each case at
least one machine room vaporizer of at least one
refrigeration machine for cooling the air in the space
which is to be air-conditioned in the machine room and
at least one driver's cab vaporizer of the same at
least one refrigeration machine for cooling the air in
the driver's cab are present. In this case, the overall
cooling capacity of the at least one refrigeration
' machine is therefore determined by the cooling
reguirement and "the electrical devices in the machine
room and that for the driver's cab or cabs.
In a further preferred embodiment of the invention, the
space which is to be air-conditioned in the machine
room is essentially completely closed off from the
outside. "Essentially" means that at most leaks are
present in the walls in the region which is to be air-
conditioned in the machine room, and said walls prevent
the space from being completely closed off from the
outside. Otherwise, these walls are sealed. An internal
air pressure which is raised compared to the ambient
air pressure in the space which is to be air-
conditioned in the machine room is generated by
pressure-generating means. This can ensure that the
risk of contamination and/or moisture entering the
machine room, even when leaks form in the outer skin of
the machine room and/or on the adjoining driver's cab
or cabs, is only relatively small because the excess
pressure ensures that at most air exits from the
machine room and contamination and/or moisture
therefore cannot enter. The pressure-generating means
used may be, for example, fans (blowers) . In
particular, it is possible to use one or more of the

traction motor fans for this purpose, or alternatively
one or more separate machine room fans.
In particular, in this case the machine room can also
be essentially completely closed off from the at least
one driver's cab. "Essentially" also means here that at
most leaks are present in the dividing wall or in the
door between the machine room and the driver's cab,
which leaks prevent the machine room from being closed
off completely from the outside. Since at least one
access to the machine room is provided, it can be
formed by a door which is sealed hermetically, i.e. in
an air-tight fashion. For this purpose, the door is
secured against air escaping in a known fashion using
sealing material. In this context it is to be borne in
mind that the interior space of driver's cabs cannot be
closed off in an airtight fashion in order, for
example, as in the machine room, to build up an air
pressure which is raised compared to the surroundings.
This is because in a driver's cab it is necessary to
ensure sufficient exchange of air for the supply of the
person who is located therein while carrying out their
activity.
The air-treatment device can be arranged in different
ways in the machine room. The position and connection
thereof depends, inter alia, on the arrangement of the
electrical devices in the machine:
In a first embodiment of the invention, at least one
rack is installed on both longitudinal sides in the
machine room, between which racks a central passage
through which it is possible to walk runs, the
electrical devices being accommodated in said racks. In
each case, at least one air-treatment device is
accommodated on each side of the central passage. Air
which is located in the machine room is sucked in by
these air-treatment devices and conducted to the racks

after suitable cooling by a duct system. From there the
air is blown out into the machine room again.
In a second embodiment of the invention, a central air-
treatment device can be provided which supplies the
racks on both sides of the central passage via air
ducts. Such an arrangement is then advantageous in
particular if a number of electrical devices are, for
example, accommodated centrally in the machine room
("power pack") and other electrical devices are
accommodated only at the two ends thereof in the
machine room, for example in racks on the two
respective sides of a central passage.
In a third embodiment of the invention, the air-
conditioning of the electrical devices in the machine
room is combined with the air-conditioning of one or
more driver's cabs. In this variant, the compartment
which contains the at least one condenser and the
compressor or compressors as well as the at least one
fan for sucking in and blowing out external air is
arranged in the machine room and preferably in the
vicinity of a driver's cab. The specified unit
supplies, via coolant lines, vaporizers, at least one
of which, the machine room vaporizer, is assigned to an
air-treatment device for the space to be air-
conditioned in the machine room, and at least one
other, the driver's cab vaporizer, is assigned to an
air-treatment device for the driver's cab or cabs. The
one vaporizer therefore serves to air-condition the
space which is to be air-conditioned in the machine
room, and the other serves to air-condition the
driver's cab or cabs. In this embodiment, a
condenser/compressor/fan unit can be dispensed with.
Furthermore, the noise level in the driver's cab is
reduced. In this case, the air circulations in the
driver's cab and those in the machine room also remain
separate, with the result that an excess pressure can

be ensured in the machine room while the driver's cab
can be supplied with fresh air.
The present invention will be explained in more detail
below with reference to figures which are described
below, of which:
Figure 1 shows a view of the machine room of a rail
vehicle in a first embodiment according to
the invention in a cross-sectional
illustration;
Figure 2 shows a view of the machine room in Figure 1
in a longitudinal sectional illustration;
Figure 3 shows a view of the machine room of a rail
vehicle in a second embodiment according to
the invention in a cross-sectional
illustration; and
Figure 4 shows a partial view of a rail vehicle in a
third embodiment according to the invention
in a cross-sectional illustration.
Identical reference symbols denote elements with the
same function in the figures.
The illustration of the machine room 13 (shown in
Figure 1) of a rail vehicle, for example of an
electrical locomotive for a long distance train, is
restricted to the wagon part of the machine room 13 and
shows neither the bogies nor the traction drives. The
electrical devices which are located in the machine
room 13, for example electronic devices with electronic
and/or micro-electronic devices for controlling the
operation of the vehicle, are not illustrated for the
purposes of clearer illustration of the invention.

In the embodiment shown in Figures 1 and 2, electrical
devices are arranged on both sides of a central passage
7 in the machine room 13, said central passage 7
leading in the longitudinal direction through the
machine room 13. On the left-hand side of the central
passage 7 there is in the illustration a rack 5' with
an electrical device installed therein, in an area 6' .
On the right-side of the central passage 7, electrical
devices are also accommodated (racks 5 with rack areas
6 illustrated in Figure 2).
In the illustration in Figure 1, an air-treatment
device 3 with a vaporizer 10, a filter 11 and a fan 12
is shown in the selected sectional plane. Furthermore,
the air-treatment device 3 has an expansion valve of a
refrigeration machine (not illustrated). Figure 2 also
illustrates that racks 5 with electrical devices are
also located in rack areas 6 provided for them,
upstream and downstream of the air-treatment device 3.
Furthermore, a compartment 14, in which a condenser 2
of a refrigeration machine and fans 9 are located, is
located above the air-treatment device 3 and also on
the right-hand side of the central passage 1 .
Furthermore, this compartment 14 also comprises a
compressor (not illustrated). The air-treatment device
3 and the compartment 14 containing the condenser 2,
the fans 9 and the compressor are installed together as
an air-conditioning device 1 in the machine room. The
condenser 2 of the upper compartment 14 and the
vaporizer 10 of the air-treatment device 3 are part of
a refrigeration machine which additionally has a
compressor in the upper compartment and an expansion
valve in the air-treatment device 3. In the same way,
corresponding air-treatment devices and compartments in
which the condenser, compressor, fan and filter are
located are also installed on the left-hand side of the
central passage 7.

Underneath the air-treatment device 3 there is an
adjoining air duct 4. This is connected to the racks 5
in which sensitive electrical devices are installed in
the rack areas 6. The air-treatment device which is
installed on the left-hand side is also connected via
corresponding duct 4' to sensitive electrical devices
present there in the rack areas 6' inside the racks 5'.
In order to perform air-conditioning of the electrical
devices in the rack area 6 of the rack 5, cooled air is
generated in the air-treatment device 3. For this
purpose, the fan 12 sucks air into the air-treatment
device 3 from the free interior of the machine room 13
(illustrated by arrows 26) and blows said air for
cleaning through the filter 11 and then through the
vaporizer 10 (illustrated by arrow 23) . As the air is
directed through the vaporizer 10, the air is cooled.
The cooled air then passes into the air duct 4 on the
right-hand side of the central passage 7 and then
directly into the racks 5 and there into the rack areas
6 containing the sensitive electrical devices
(illustrated by arrow 24) . After contact between the
cooled air and the electrical devices, with the result
that the latter are cooled, the air is directed into
the free interior space of the machine room 13
(illustrated by arrows 25) . The air there cools the
interior space of the machine room 13. In a
corresponding way, the air is cooled by the air-
treatment device on the left-hand side of the machine
room 13 and directed into the racks 5' and the rack
areas 6' arranged therein.
The condenser 2 of the upper component 14 and the
vaporizer 10 of the air-treatment device 3 are
components of a cooling circuit of a refrigeration
machine (not illustrated). In order to generate the
cooling capacity of the vaporizer 10, the condenser 2
conducts away heat. For this purpose, the fans 9 suck,

through openings in the external wall of the rail
vehicle, external air into the compartment 14 in which
the condenser 2 and the fans 9 are located (illustrated
by arrows 21) . The sucked-in external air is heated
through heat being given off by the condenser 2, and
said external air passes through an opening in the
compartment floor to the outside again (illustrated by
arrows 22) . Such an air-conditioning device with a
condenser, compressor, fan and filter in a compartment
which is open to the outside and an air-treatment
system with a vaporizer, expansion valve, filter and
fan, coolant being circulated between the condenser and
the vaporizer and transporting heat in the process, is
also installed on the left-hand side of the machine
room 13.
So that exclusively cleaned air can circulate in a
closed circuit within the space to be air-conditioned
in the machine room 13, the compartment 14 which
contains the condenser 2 and the fans 9 is -separated
from the air-treatment device 3 by a wall 15 which is
impermeable to air. This wall 15 is also preferably
thermally insulated in order to avoid transfer of heat
from the condenser 2 to the vaporizer 10 and/or between
the surroundings thereof.
In order to generate a pressure in the machine room 13
which is raised compared to the pressure in the
surroundings, it is possible to additionally provide a
further fan which blows air from the outside into the
machine room 13. So that this air does not contaminate
the machine room 13, this air is carefully cleaned.
Since relatively large quantities of air do not have to
be formed to generate the overpressure, the risk of
contamination of the machine room is low.
Figure 3 shows a second embodiment of the invention.
The principle of the internal air circulation in the

machine room 13 is basically independent of the
positioning of the air-conditioning system. In the
arrangement shown in this figure, the component
containing the condenser and the compressor as well as
at least one fan, and the air-treatment device with the
vaporizer, the expansion valve, the at least one fan
and the filter, are located in an air-conditioning
device 1 on the roof of the rail vehicle. Cooled and
purified air is directed from the vaporizer in the air-
treatment device into an air duct 8 between the air-
conditioning device 1 and the air duct 4 on the right-
hand side of the central passage of the vehicle
(illustrated by arrow 23). In order to conduct away the
heat produced in the condenser, external air is sucked
into the compartment of the air-conditioning device 1
(illustrated by arrows 21) and the air heated up by the
condenser is discharged to the outside again
(illustrated by arrows 22) . The cooled air which has
passed into the air duct 8 is then directed, as in the
embodiment in Figures 1 and 2, via the air duct 4 into
the racks and there into the rack areas containing the
sensitive electrical devices, also on the right-hand
side of the vehicle (not illustrated). After cooling of
the electrical devices, the air passes into the free
interior space of the machine room 13 and is sucked
from there into the air-conditioning device 1
(illustrated by arrows 26) again. In a corresponding
way cooled air passes via an air duct, which is fed
from the air-conditioning device 1 and leads downwards,
on the left-hand side of the central passage of the
vehicle (not illustrated) into a horizontal air duct 4'
which supplies the racks 5' and the sensitive
electrical devices therein with the cooled air in rack
areas 6' (illustrated by arrow 24) - From there the air
passes again into the free interior space of the
machine room 13 (illustrated by arrow 25) and from
there into the air-conditioning device 1 (illustrated
by arrows 26).

A third embodiment of the invention is illustrated in
Figure 4. In the longitudinal illustration of this
figure, not only the machine room 13 but also an end-
side driver's cab 30 and a wall 34 which separates the
machine room 13 from this driver's cab 30 are shown.
This wall 34 is embodied in an air-tight fashion. A
door (not shown) which is present in this wall 34 has
seals which also permit the machine room 13 to be
completely sealed off from the driver's cab 30.
In this case, an air-treatment device 32 with a
vaporizer, filter and, if appropriate, a heating system
is installed on the roof of the rail vehicle in the
region of the driver's cab 30 and serves to supply the
driver's cab 30. The actual air-conditioning device 1
with the compartment for the condenser, compressor,
filter and the fans as well as also with an air-
conditioning device for the machine room 13 is
accommodated in the machine room 13. The condenser and
the compressor of this air-conditioning device 1 are
dimensioned to supply both the machine room 13 and the
driver's cab 30. The vaporizer and the expansion valve
in the air-treatment device 32 of the driver's cab 30
serve exclusively to cool the driver's cab 30 and are
therefore correspondingly dimensioned. In a
corresponding way, the vaporizer and the expansion
valve in the air-treatment device of the machine room
13 are dimensioned for the supply thereof.
In order to produce a refrigeration circuit between the
condenser and the compressor in the air-conditioning
device 1 in the machine room, on the one hand, and the
vaporizer and expansion valve in the air-treatment
device 32 for the driver's cab 30, on the other hand,
pipelines 33 are present.

There therefore exist two cooling air circulations
which are independent of one another: a cooling air
circulation for cooling the driver's cab 30 and cooling
air circulation for cooling the machine room 13. By-
separating the vaporizers in the air-treatment device
32 for the driver's cab 30, on the one hand, and the
vaporizers in the air-treatment device in the machine
room air-conditioning device 1, on the other hand, two
independent cooling air circulations are therefore
provided. The cooling air in the machine room 13 can
therefore be placed at a raised pressure independently
of the air pressure in the driver's cab 30, with the
result that excess pressure in the machine room 13 and
a supply of fresh air in the driver's cab 30 can be
ensured.
Moreover, the design of the air-conditioning system in
the machine room 13 and the method of functioning
thereof are the same as in the embodiments in Figures
1-3.

We claim:
1. Rail vehicle having a machine room (13) for
accommodating electrical devices, and having at
least one driver's cab (30), wherein the rail
vehicle comprises an air-conditioning system,
provided for generating cooled air serving to cool
the electrical devices, for the machine room (13),
characterized in that the cooled air is conducted
in an air circulation (23, 24, 25, 26) which
circulates exclusively inside a space which is to
be air-conditioned in the machine room (13).
2. Rail vehicle according to Claim 1, characterized
in that the cooled air is directed in a targeted
fashion to the electrical devices by means of air-
conducting means (4, 4', 8).
3. Rail vehicle according to one of the preceding
claims, characterized in that the air-conditioning
system comprises at least one air-treatment device
(3) and air ducts (4, 4', 8) in which the cooled
air is directed in a targeted fashion to the
electrical devices.
4. Rail vehicle according to Claim 3, characterized
in that, after contact with the electrical
devices, the cooled air passes through the free
interior space of the machine room (13) to the at
least one air-treatment device (3).
5. Rail vehicle according to one of Claims 3 and 4,
characterized in that the at least one air-
treatment device (3) comprises filter means (11)
for the cooled air.
6. Rail vehicle according to one of the preceding
claims, characterized in that the space which is

to be air-conditioned in the machine room (13) is
essentially completely closed off from the
outside, and an internal air pressure which is
raised compared to the ambient air pressure is
generated in the space by pressure-generating
means.
Rail vehicle according to Claim 6, characterized
in that the machine room (13) is also essentially
completely closed off from the at least one
driver's cab (30).
Rail vehicle according to one of the preceding
claims, characterized in that the air-conditioning
system comprises at least one refrigeration
machine (2, 10) for cooling the air.
Rail vehicle according to Claim 8, characterized
in that the at least one refrigeration machine (2,
10) comprises in each case at least one vaporizer
(10) for cooling the air, and in that the at least
one vaporizer (10) is in each case a component of
an air-treatment device (3) of the air-
conditioning system, in which air-treatment device
(3) the cooled air is generated.
Rail vehicle according to one of Claims 8 and 9,
characterized in that the at least one
refrigeration machine (2, 10) is dimensioned for
exclusively cooling the area which is to be air-
conditioned in the machine room (13).
Rail vehicle according to Claim 8, characterized
in that in each case at least one machine room
vaporizer (10) for cooling the air in the area
which is to be air-conditioned in the machine room
(13) and at least one driver's cab vaporizer for

cooling the air in the driver's cab (30) are
present.
12. Method for cooling at least one electrical device
in a machine room (13) of a rail vehicle,
comprising the generation of cooled air by means
of an air-conditioning system which the rail
vehicle comprises,
characterized in that the cooled air is conducted
in an air circulation which circulates exclusively
inside an area which is to be air-conditioned in
the machine room (13).

In order to increase the fail-safety of sensitive electrical
devices in the machine room 13 of a rail vehicle which
additionally has at least one driver's cab 30, there is
provision that the rail vehicle comprises an air-conditioning
system, provided for generating cooled air serving to cool
the electrical devices, for the machine room 13. In addition,
it is ensured according to the invention that the cooled air
is conducted in an air circulation 23, 24, 25, 26 which
circulates exclusively inside a space which is to be air-
conditioned in the machine room 13.