Note: Descriptions are shown in the official language in which they were submitted.
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kir conditioning systeom for a motor vehicle
The invention relates to an air conditioning system for a
vehicle having a refrigerant circuit which comprises a com-
pressor, a condenser, an expansion valve and a latent cold
storage the heat of which can be drawn by means of the re-
frigerant circuit. This drawing of heat is referred to as
charging. Furthermore, the air conditioning system com-
prises means for cooling air, which is formed such that
heat is drawn from the air and the heat is supplied to the
latent cold storage. This supply of heat is referred to as
discharging. In particular, such an air conditioning system
is used for motor trucks. In particular, it is used there
as a stationary air conditioning system.
A stationary air conditioning system for a vehicle is known
from DE 198 52 641 Cl, having a refrigerant circuit with a
compressor, a liquefier, an accumulator and at least one
ice storage unit. The ice accumulator unit consists of a
vaporizer with an expansion organ and an ice accumulator
surrounding the latter. Furthermore, a further vaporizer
with an expansion organ is connected in parallel to the at
least one ice accumulator unit, wherein it can be con-
trolled by means of respective switching valves, if the re-
frigerant flows through the further vaporizer or the vapor-
izer of the ice accumulator unit. The compressor is me-
chanically driven by a driving motor of the vehicle and can
be coupled with the latter by means of a magnetic clutch
via a fan belt.
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It is the object of the invention to provide a compact air
conditioning system which is adapted to cool a vehicle in a
stationary operation of the vehicle.
This object is solved by the features of the independent
claims. Further advantageous formations of the invention
are subject matter of the dependent claims.
The invention is characterized by an air conditioning sys-
tem for a vehicle having a first refrigerant circuit which
comprises an electrically driven compressor, a condenser,
an expansion valve and a latent cold storage the heat of
which is drawn by means of the refrigerant circuit, and
having means for cooling air which is formed such that heat
is drawn from the air and the heat is supplied to the la-
tent cold storage. By means of the electrically driven com-
pressor the power of the compressor can be adjusted inde-
pendently on the rotational speed of a driving shaft of the
vehicle and, if necessary, the compressor can also be pro-
vided with electrical energy independently on the drive of
the vehicle. Thereby, a predetermined amount of heat can be
drawn from the latent cold storage in the simply manner
also during extreme hotness.
If a further primary air conditioning system is disposed in
the vehicle, the compressor of which is driven by the driv-
ing shaft of the vehicle, for example by the crank shaft,
the charging of the latent cold storage of the air condi-
tioning system can also be affected quickly when the com-
pressor of the primary air conditioning system is operated
at its maximal capacity.
The latent cold storage is characterized by a very high
specific cold capacity. This has the advantage that the air
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conditioning system can be formed very compact. In particu-
lar, it can draw a high amount of heat from the air in the
stationary operation of the vehicle when the driving shaft
does not rotate.
In an advantageous formation of the invention, the air con-
ditioning system hast a refrigerant circuit which comprises
a pump, the latent cold storage and a heat exchanger by
means of which heat is drawn from the air and the heat is
then supplied to the latent cold storage. This has the ad-
vantage that the heat exchanger can be disposed at any po-
sition in the vehicle.
In a further advantageous formation of the invention, a
blower is assigned to the heat exchanger which influences
the air flow through the heat exchanger and simultaneously
influences the air flow through a heating element. This has
the advantage that only one blower is necessary for cooling
the air on the one hand and for heating the air on the
other hand.
In particular, it is advantageous when the heating element
is a heating heat exchanger through which a fluid flows
which can be heated by means of a fuel heating device. With
a heating element formed in such a manner a notably high
heating power is possible.
In a further advantageous formation of the invention, the
latent cold storage is disposed such that the air to be
cooled flows through the latent cold storage and, at the
same time, is cooled by the latter. Thus, the air condi-
tioning system can be formed notably compact. In this con-
text it is notably advantageous when the refrigerant cir-
cuit comprises a plurality of latent cold storages. Accord-
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ingly, cooling at many positions of the vehicle can be af-
fected. In particular, this is advantageous in motor trucks
which have, besides a driver compartment, a sleeping/living
compartment formed separately of the latter.
In a further advantageous formation of the invention, a
generator is assigned to the air conditioning system which
is driven by a driving shaft of a drive of the combustion
engine and, thus, provides the electrical energy of the
electrically driven compressor. In such a manner, the elec-
trical driven compressor can be operated with high power
during the driving operation.
Embodiments of the invention are illustrated on the basis
of the schematical drawings, wherein:
Figure 1 shows a first embodiment of the air conditioning
system,
Figure 2 shows a second embodiment of the air conditioning
system,
Figure 3 shows a third embodiment of the air conditioning
system,
Figure 4 shows a fourth embodiment of the air conditioning
system,
Figure 5 shows a fifth embodiment of the air conditioning
system,
Figure 6 shows a sixth embodiment of the air conditioning
system.
Elements of the same construction and function are identi-
fied with the same reference numerals in all drawings.
An air conditioning system (figure 1) is disposed in a ve-
hicle, in particular in a motor truck. It has a refrigerant
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circuit 1 which comprises an electrically driven compressor
2, a condenser 4 which has assigned a condenser blower 6
thereto, an accumulator 8, an expansion valve 10 and a la-
tent cold storage 12.
The expansion valve 10 can be controlled or can merely be
formed as a flow restrictor. The compressor 2 is connected
with its output to the condenser 4 via a first line 14
which, in turn, is connected with its output to the accumu-
lator 8 via a second line 16, which, preferably, also com-
prises a drier. The accumulator 8 is connected with the ex-
pansion valve 10 via a third line 18, which is connected
with its output to the latent cold storage via a fifth line
22. The latent cold storage 12 is connected with its output
to an input of the compressor 2 via a fifth line 22. The
electrically driven compressor 2 is preferably supplied
with electrical energy from a generator 24 which is driven
by a driving shaft 26 of a drive 28 of the vehicle. For ex-
ample, the drive 28 can be a combustion engine. However,
the electrically driven compressor can also be supplied
with electrical energy in another way, for example by means
of a fuel cell or any elements outputting electrical en-
ergy, for example a battery. Also, the electrically driven
compressor can be supplied with electrical energy by any
combination of the elements enumerated exemplary. By a re-
spective dimensioning of these elements, the electrically
driven compressor 2 can be operated with a power which is
sufficient also under extreme operating conditions in order
to draw the desired amount of heat from the latent cold
storage 12.
During the operation of the electrically driven compressor
2, the refrigerant which can be for example R134a or also
CO2 is compressed, whereby its temperature increases. The
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condenser 4 is formed in cooperation with the condenser
blower 6 such that heat is drawn from the refrigerant by
the air flowing through the condenser 4.
The thus cooled and liquefied refrigerant flows further to
the accumulator 8 via the second line 16 and, thence, to
the expansion valve 10 via the third line 18 by means of
which it is expanded to a lower pressure, wherein the tem-
perature of the refrigerant decreases significantly. Subse-
quently, the refrigerant flows to the latent cold storage
12 and, there, draws heat from the cold storage medium by
vaporizing it. The refrigerant which is then gaseous again
flows further to the electrically driven compressor 2 via
the fifth line 22 and, there, is compressed again.
The high specific cold capacity of the latent cold storage
12 results from the fact that the cold storage medium in
the latent cold storage is drawn energy by means of the re-
frigerant such that a phase transition from a liquid state
to a solid state occurs. Thus, the latent cold storage can
be formed compact. Furthermore it can be produced cheap.
When the refrigerant is CO2, it is preferred that the con-
denser 4 is a gas cooler and the lines 18, 22 contact each
other in a internal heat exchanger and the accumulator is
disposed in the line 22.
The air conditioning system comprises a refrigerant circuit
30 which has a heat exchanger 32, a pump 34 and a latent
cold storage 12. The latent cold storage 12 is connected to
the heat exchanger 32 via a sixth line 36 an output of
which is connected with an input of the pump 34 via a sev-
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enth line 38. The pump 34 is connected with its output to
the latent cold storage 12 via an eighth line 40.
Preferably, the pump 34 is electrically driven and, for ex-
ample, can obtain the electrical energy necessary for it
from a battery not shown. The pump 34 pumps the refrigerant
of the refrigerant circuit through the latent cold storage
12, wherein the latent cold storage 12 is supplied with
heat and is cooled in this manner. The cooled refrigerant
then pours or flows to the heat exchanger 32 through the
sixth line 36 which is supplied with air by a blower 42 in
a controlled manner which then delivers the heat to the
heat exchanger 32 and, thus, is cooled and contributes to
the desired cooling of the internal space of the vehicle.
The heat exchanger 32 can be disposed in the region of the
passenger compartment or can also be disposed in a sleeping
or living room of the vehicle. The heat delivered from the
flowing air heats the refrigerant in the heat exchanger 32
and, thus, the heated refrigerant flows to the pump 34 via
the seventh line 38 where it is pumped again to the latent
cold storage 12.
It is preferred that the electrically driven compressor 2
is operated during the driving operation of the vehicle
and, thus, heat is drawn from the latent cold storage 12.
During the stationary operation of the vehicle, it is pre-
ferred that the compressor 22 is not operated or, at the
most, is operated with a low electrical power. In the sta-
tionary operation the pump 34 is driven dependent on the
required cooling power and, accordingly, air is cooled in
the vehicle by means of the refrigerant circuit 30.
In a second embodiment (figure 2) of the invention, in ad-
dition a heating element is provided which is a heating
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heat exchanger 44, wherein fluid, preferably a water glycol
mixture, is flowing through the latter which can be heated
by means of a fuel heating device 46 and is supplied to the
heating heat exchanger 44 via a ninth line 48. The heating
heat exchanger 44 is disposed such that the blower 44 also
controls the air flowing through the heating heat exchanger
44. Thus, simply with one blower 44, the air flowing
through both the heating heat exchanger 44 and the air
flowing through the heat exchanger 32 can be controlled.
In a third embodiment (figure 3) of the air conditioning
system, an air heating element 50 is provided which, for
example, can be formed as a PTC-resistance element and,
thus, transforms electrical energy to heat and which is
disposed such that the amount of air which flows next to
the air heating element 50 is controlled by means of the
blower 42. For example, the air heating element 50 can be
formed as fuel air heating device.
In a fourth embodiment (figure 4) of the air conditioning
system, the blower 42 is assigned to the latent cold stor-
age 12 and controls such that the air to be cooled flows
through the latent cold storage or flows next to cooling
fins which are assigned to the latter and, thus, delivers
heat to the latent cold storage 12 and is thus cooled. In
this way the air conditioning system can be formed notably
compact, since the refrigerant circuit 30 can be omitted,
in particular when at the plurality of positions of the ve-
hicle, a cooling of the air has to be affected, it is ad-
vantageous in this context when the air conditioning system
comprises a plurality of latent cold storages 12. This plu-
rality of latent cold storages 12 can then be disposed at
respective positions of the vehicle, for example the latent
cold storage 12 in a motor truck can be disposed in the
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passenger compartment and the further latent cold storage
12 can be disposed in a sleeping and/or living room which
is separately formed of the latter.
In the fourth embodiment of the air conditioning system,
the fuel heating device 46 and the heating heat exchanger
44 or the air heating element 50 according to the embodi-
ments of figures 2 and 3 can also exist.
In a fifth embodiment of the air conditioning system (fig-
ure 5), the fuel heating device 46 is disposed in a bypass
48 of the refrigerant circuit 30. In a sixth embodiment of
the air conditioning system, the fuel heating device 46 is
coupled to the sixth line 36.
