DE102018209769A1 - Method for operating a refrigeration system of a vehicle having a refrigerant circuit - Google Patents

Abstract

The invention relates to a method for operating a refrigerant circuit (10) of a refrigeration system of a vehicle with a chiller branch (1.0) which has a chiller (1), a first expansion element (AE1) and a first pressure-temperature sensor (pT1), - at least one interior evaporator branch (2.0), which has an interior evaporator (2) and a second expansion element (AE2) and the chiller branch (1.0) is connected in parallel, - a refrigerant compressor (3) and a condenser or gas cooler ( 4), - in a single chiller mode, the operating point of the refrigerant circuit (10) at the refrigerant outlet of the chiller (1) is set near the dew line of the refrigerant, - the low pressure and the associated temperature of the refrigerant by means of the first pressure-temperature sensor ( pT1) of the chiller (1) is detected, and - the low pressure by controlling the refrigerant compressor (3) to one of the ambient conditions and the required cooling capacity The maximum low pressure value dependent on the chiller (1) is limited or reduced while reducing the cooling capacity on the chiller (1) if a torque overload is detected on the refrigerant compressor (3) or a predetermined deviation of the temperature from the tauline of the refrigerant at the refrigerant outlet of the chiller ( 1) is detected.

Description

The invention relates to a method for operating a refrigerant circuit for a vehicle with at least two evaporators, namely at least one interior evaporator and an evaporator designed as a chiller.

The interior evaporator can be designed as a front evaporator and / or as a rear evaporator of the vehicle interior and is used to condition an incoming air flow entering the vehicle interior.

In addition to the interior or front evaporator, electrified vehicles require a separate coolant circuit for the conditioning and temperature control of the energy store, which is usually implemented as a high-voltage battery. Such a coolant circuit is coupled to the refrigerant circuit by means of a heat exchanger, such a heat exchanger in turn also being designed as an evaporator for cooling an air stream or as a so-called chiller for cooling a coolant, as is known, for example, from US Pat DE 10 2017 108 809 A1 , the DE 10 2016 108 468 A1 or the DE 10 2009 015 658 A1 is known.

The DE 10 2016 117 075 A1 describes a system in which a high-voltage battery of a hybrid or electric vehicle is cooled by means of a coolant circuit which has a coolant-coolant heat exchanger which is thermally coupled to a coolant circuit. In order to reduce the need for refrigerant-based evaporators, the coolant from the coolant circuit is also used for cooling a rear zone of the passenger compartment using a coolant-air heat exchanger. In addition, a passive cooling mode is also provided for the high-voltage battery by means of a passive cooler which is exposed to the ambient air of the vehicle.

In a similar way, the DE 10 2014 001 022 A1 a coolant circuit for a high-voltage battery, which is thermally coupled to a refrigerant circuit via a heat exchanger. This coolant circuit has a cooler which is acted upon by the ambient air of the vehicle. This cooler can be bypassed using a bypass line.

From the DE 10 2009 021 530 A1 A coolant circuit for a high-voltage battery is known, in which both an air-coolant heat exchanger and a chiller thermally coupled to a refrigerant circuit are arranged. The coolant circuit is constructed in such a way that the coolant can be passed either only through the air-coolant heat exchanger or only through the chiller or through both components.

Finally, be on DE 10 2011 118 162 B4 referenced, from which a refrigerant circuit having a plurality of evaporators with a heat pump function is known. In addition to an interior evaporator, a first and a second chiller are also provided for this refrigerant circuit, an expansion element being connected upstream of these evaporators. In addition, a further expansion element is connected downstream of the interior evaporator, as a result of which this interior evaporator can be operated at an intermediate pressure level. Finally, a condenser intended for cooling operation is used to implement an air heat pump as a heat pump evaporator with an associated expansion element.

It is an object of the invention to provide a method for operating a refrigeration system of a vehicle having a refrigerant circuit with at least two evaporators, namely at least one interior evaporator and one evaporator designed as a chiller, with which in single-chiller mode, that is to say during an exclusive operation of the Chillers a functionally reliable and therefore error-free operation of the refrigerant circuit is ensured.

This object is achieved by a method having the features of patent claim 1.

• - einem Chiller-Zweig, welcher einen Chiller, ein erstes Expansionsorgan und einen stromabwärts des Chillers nachgeschalteten Druck-Temperatursensor aufweist und mit einem Kühlmittelkreislauf thermisch gekoppelt ist,
• - wenigstens einem Innenraum-Verdampferzweig, welcher einen Innenraum-Verdampfer und ein zweites Expansionsorgan aufweist und dem Chiller-Zweig parallel geschaltet ist,
• - einem Kältemittelverdichter, und
• - einem Kondensator oder Gaskühler, wird
• - in einem Single-Chiller-Modus der Betriebspunkt des Kältemittelkreislaufs am Kältemittelaustritt des Chillers nahe der Taulinie des Kältemittels eingestellt,
• - der Niederdruck und die zugehörige Temperatur des Kältemittels mittels des Druck-Temperatursensors des Chillers detektiert, und
• - der Niederdruck durch Steuerung des Kältemittelverdichters auf einen von Umgebungsbedingungen und der benötigten Kälteleistung des Chillers abhängigen maximalen Niederdruckwert beschränkt oder unter Reduzierung der Kälteleistung an dem Chiller abgesenkt, wenn eine Drehmomentüberlastung am Kältemittelverdichter oder eine vorgegebene Abweichung der Temperatur von der Taulinie des Kältemittels am Kältemittelaustritt des Chillers detektiert wird.

In this method for operating a refrigerant circuit of a refrigeration system of a vehicle

• a chiller branch which has a chiller, a first expansion element and a pressure-temperature sensor connected downstream of the chiller and is thermally coupled to a coolant circuit,
• at least one interior evaporator branch, which has an interior evaporator and a second expansion element and is connected in parallel with the chiller branch,
• - a refrigerant compressor, and
• - a condenser or gas cooler
• in a single chiller mode, the operating point of the refrigerant circuit at the refrigerant outlet of the chiller is set close to the dew line of the refrigerant,
• - Detects the low pressure and the associated temperature of the refrigerant by means of the pressure-temperature sensor of the chiller, and
• - The low pressure by controlling the refrigerant compressor to one of Ambient conditions and the required refrigeration capacity of the chiller-dependent maximum low pressure value is limited or reduced while reducing the refrigeration capacity on the chiller if a torque overload on the refrigerant compressor or a predetermined deviation of the temperature from the dew line of the refrigerant at the refrigerant outlet of the chiller is detected.

In order to avoid the disadvantages threatening with a high low pressure in single chiller mode and thus with a high evaporation temperature of the refrigerant, the efficient operation of the refrigerant circuit associated with the operation of the refrigerant at the refrigerant outlet of the chiller is close to the dew line, which is particularly useful for systems is significant with refrigerant storage arranged on the high-pressure side, only slightly worsened by either limiting the low pressure to a maximum permissible low pressure value or detecting the low pressure while maintaining a torque overload on the refrigerant compressor or when the temperature deviates from the dew line of the refrigerant at the refrigerant outlet of the chiller Cooling capacity, but a loss in system efficiency when the chiller is lowered.

With the increasing low pressure of the refrigerant, usually if this is also coupled to an increasing coolant inlet temperature in the chiller, its density also increases and thus leads to an increased refrigerant requirement in the low-pressure section of the refrigerant circuit, i.e. the risk of an underfilling of refrigerant increases, which can ultimately result in an underfilling of refrigerant. This means that in single-chiller mode, the refrigerant at the refrigerant outlet of the chiller can no longer be operated close to the dew line, the refrigerant increasingly overheats. Ideally, when the cooling capacity is required, the low pressure is only increased until an increase in the value of the overheating of the refrigerant is detected for the first time, and from this point onwards the low pressure tends to decrease slightly. It must be taken into account that the desired cooling capacity from the interaction of low pressure is set via the refrigerant compressor and close to the dew line via the first expansion element.

With the reduction in low pressure, the evaporation temperature is also reduced. Here, the low pressure is reduced to a value by regulating the refrigerant compressor at which the system operating point is again set close to the dew line for efficient system operation. Since there may now be an option in the room to provide more cooling capacity than is ultimately required by the system, (high-frequency) on-off operation or two-point control operation of the refrigeration system would be conceivable. In addition, the system could work with excess cooling capacity for a longer period of time before the cooling circuit is idle for a longer period in the sense of a low-frequency two-point control mode.

A third option is the setting of a typical maximum low pressure of the refrigerant circuit, for example 4.5 bar with an R1234yf system, with increasing overheating due to the reduction of the refrigerant mass flow via the first expansion element.

The maximum low pressure value is determined depending on the ambient conditions and the current cooling capacity of the chiller. The environmental conditions relate, for example, to the ambient temperature, i.e. As the evaporation temperature, a value below the ambient temperature should be set when the refrigerant circuit starts up so that the operating point, which is optimized for efficiency, can be restarted with the duration of operation, taking into account the values at the first pressure / temperature sensor. The current cooling capacity of the chiller determines the maximum low pressure value in such a way that as the cooling capacity requirement on the coolant side of the chiller decreases, an increasing value of the low pressure level tends to become apparent.

The detection of the torque overload on the refrigerant compressor is realized in an electrically driven refrigerant compressor in that such a refrigerant compressor generates an error signal in the event of a torque overload, which is fed to a control unit of the refrigerant circuit, for example an air conditioning control unit. In the case of a refrigerant compressor that is driven mechanically, for example by an internal combustion engine, a torque overload is detected in that the non-positive connection of the magnetic coupling is caused to slip.

According to an advantageous development of the invention, following the lowering of the low pressure, the cooling capacity at the chiller is adjusted again to the target cooling capacity by means of a regulation of the first expansion element together with the refrigerant compressor. The cooling power that is generated by the chiller before the lowering of the low pressure is thus generated again by the chiller, but at an operating point with lower efficiency compared to the operating point set before the lowering of the low pressure. On the system side, the pressure difference between the low and high pressure side and thus the pressure ratio is increased.

• - der Kältemittelkreislauf mit einem Niederdruck-Kältemittelsammler ausgebildet wird, mit welchem definierte Kältemitteldampfgehalte einstellbar sind, und
• - das Kältemittel zur Einstellung auf dessen Taulinie oder nahe der Taulinie im Zwei-Phasen-Gebiet des Kältemittels mittels des Niederdruck-Kältemittelsammlers auf einen Überhitzungsgrad von 0 K eingestellt wird.

Another advantageous embodiment provides that

• - the refrigerant circuit is designed with a low-pressure refrigerant collector, with which defined refrigerant vapor contents can be set, and
• - The refrigerant is adjusted to the dew line or close to the dew line in the two-phase region of the refrigerant by means of the low-pressure refrigerant collector to a degree of overheating of 0 K.

In this case, the property of the low-pressure side accumulator is used, that in single-chiller mode it sets a constant vapor content, thus a defined refrigerant quality, that is, overheating with a value of zero occurs at the refrigerant outlet of the chiller. H. the condition of the refrigerant is set to its dew line or to the left of it in the two-phase area of the refrigerant. The first expansion element belonging to the chiller is used to control the cooling of the refrigerant at the outlet of the condenser or gas cooler for the subcritical operation of the refrigeration system on the basis of the recorded values for pressure and temperature or to regulate it to an optimal high pressure for the refrigeration system the measured refrigerant temperature at the outlet of the gas cooler, which in turn serves as an input variable for the target high pressure for setting the operating point to achieve the optimal system efficiency.

If an increase in low pressure occurs in single chiller mode and one of the disadvantageous consequences (torque overload at the refrigerant compressor or increasing overheating of the refrigerant at the refrigerant outlet of the chiller) is detected, the low pressure is either limited to the maximum low pressure value or to by controlling the refrigerant compressor accordingly lowered a value below this maximum low pressure value. Then the cooling capacity of the chiller is restored to the value reached before the low pressure was reduced by the corresponding interaction of the refrigerant compressor by increasing the stroke or speed and the expansion device as a rule. adjusted by further throttling. It should be taken into account that there can be situations in which the refrigerant circuit can work as a system independent of the supercooling control or the control of the optimal high pressure. In this case, an operating point is set with a lower efficiency than the operating point reached before the lowering of the low pressure.

With increasing low pressure, the chiller output can be reduced at a fixed coolant supply temperature and at the same time by subcooling or optimum high pressure set by means of the first expansion element, down to an operating point at which possible critical operating limits (overheating, torque) are achieved. From this point on, no further power reduction is possible, the system has reached a limit.

• - der Kältemittelkreislauf mit einem Hochdruck-Kältemittelsammler ausgebildet wird, und
• - das Kältemittel zur Einstellung auf oder nahe dessen Taulinie mittels des ersten erstes Expansionsorgans auf einen Überhitzungsgrad mit einem Wert zwischen 3 und 5 K geregelt wird.

An alternative and advantageous embodiment provides that

• - The refrigerant circuit is formed with a high-pressure refrigerant collector, and
• - The refrigerant is set to or near its dew line by means of the first first expansion element to a degree of overheating with a value between 3 and 5 K.

In such a refrigerant circuit with a refrigerant collector on the high-pressure side, the operating point of the refrigerant at the refrigerant outlet of the chiller is set to or near its chill line by using the first, i.e. a degree of overheating with a value between 3 and 5 K is regulated in the expansion device belonging to the chiller. The low pressure position is set with the refrigerant compressor. If the refrigerating capacity to be provided by the chiller increases, in particular when the coolant supply temperature remains the same, the low pressure rises at the same time, and not insignificantly above standard operating pressure values of a refrigeration system operation for indoor air conditioning, until either a torque overload of the refrigerant compressor is detected or due to the increasing density of the refrigerant and the The associated lack of refrigerant charge increases the degree of overheating, i.e. it can no longer be regulated to a value between 3 and 5 K and, as a result, the low pressure is either limited to the maximum low pressure value by appropriate control of the refrigerant compressor, or reduced while increasing the cooling capacity of the chiller, assuming the coolant flow temperature remains the same becomes. The cooling capacity of the chiller is then restored to the value reached before the low pressure was reduced by the corresponding interaction of the refrigerant compressor by increasing the stroke or speed and the expansion element, usually. raised by further throttling. It should be taken into account that there can be situations in which the system can work independently of the setting of the optimal degree of overheating or, if necessary, provide more cooling capacity than is required. An operating point is set with a lower efficiency than the operating point reached before the low pressure was reduced.

• - der Innenraum-Verdampfer auf einem Mitteldruckniveau-Niveau betrieben wird, und
• - der Chiller in Abhängigkeit der angeforderten Kühlleistung durch Regelung des Kältemittelverdichters und des ersten Expansionsorgans auf einem Niederdruck-Niveau betrieben wird.

According to a further preferred embodiment of the invention, in a chiller and evaporator operation, the interior evaporator is followed by a third expansion element downstream, wherein

• - the interior evaporator is operated at a medium pressure level, and
• - The chiller is operated at a low pressure level depending on the requested cooling capacity by regulating the refrigerant compressor and the first expansion element.

In such a multiple evaporator operation, the interior evaporator becomes the reference variable for the refrigerant process and specifies the low pressure level and thus the required evaporation temperature. If the refrigerant circuit has a low-pressure refrigerant collector, i.e. an accumulator on the low-pressure side, such an accumulator regulates the vapor content of the refrigerant at the outlet of the evaporator that generates the highest cooling capacity and thus delivers the largest refrigerant mass flow. The vapor content actively set by this low-pressure side accumulator occurs here in the steady state of the refrigerant circuit both at the outlet of the evaporator with the highest cooling capacity and at the refrigerant outlet of the accumulator.

In such a dual mode, the interior evaporator is followed by an electrically or mechanically controllable third expansion element, which ensures that in the interior evaporator branch there is no drop below a low pressure leading to icing. With this third expansion element, a medium pressure level is set in the interior evaporator branch, while in the chiller an arbitrary low pressure level is set by means of the compressor depending on the required cooling capacity of the chiller. The degree of overheating is set with the first expansion element assigned to the chiller, the cooling capacity of the chiller being able to be varied as a function of the degree of overheating at the respective low pressure. The maximum cooling capacity of the chiller is achieved when the refrigerant at the refrigerant outlet of the chiller is operated close to the dew line by regulating the degree of overheating to a value between 3 and 5 K by means of the expansion device. In fact, the maximum cooling capacity for a certain low pressure is achieved when the outlet state of the refrigerant at the chiller is slightly below the dew line, but due to the coupling of pressure and temperature, neither this point nor the dew line itself can be precisely adjusted and therefore becomes system operation is geared towards the low overheating values mentioned.

• - der Kältemittelzustand am Kältemittelaustritt des Chillers nahe an dessen Taulinie eingestellt, und
• - der Innenraum-Verdampfer mittels des dritten Expansionsorgans auf einem Mitteldruck-Niveau betrieben.

According to an advantageous development of the multi-evaporator operation according to the invention, the chiller is at a lower pressure than the low pressure of the interior evaporator to increase the cooling capacity of the chiller

• - The refrigerant state at the refrigerant outlet of the chiller is set close to its dew line, and
• - The interior evaporator operated by means of the third expansion element at a medium pressure level.

In this embodiment of the invention, the low pressure of the chiller is preferably raised to the low pressure of the evaporator in order to reduce the cooling capacity of the chiller by regulating the refrigerant compressor. This would mean the same operating situation as without the third expansion organ.

According to another preferred embodiment of the invention, at a low pressure of the chiller corresponding to the low pressure of the interior evaporator, a maximum cooling capacity is generated at the chiller if the condition of the refrigerant at the refrigerant outlet of the chiller is set close to its dew line. The maximum performance of the chiller is therefore achieved with minimal overheating of the refrigerant at the refrigerant outlet of the chiller, and tends to be shifted even more towards the two-phase area of the refrigerant; however, these points cannot be detected by the system and can therefore not be set stably

In this embodiment of the invention, the cooling capacity of the chiller is preferably reduced by increasing the superheating of the refrigerant by means of the first expansion element at constant pressure in the interior evaporator at a low pressure of the chiller corresponding to the low pressure of the interior evaporator.

If a system with a high-pressure side refrigerant collector is used, a pressure-temperature sensor must be connected to the corresponding evaporators for the parallel operation of the at least two evaporators (interior evaporator, chiller), in order to be able to separately detect and actively influence the respective refrigerant states. If it is impossible that the respective evaporators are operated in parallel, one of the two pressure-temperature sensors can be dispensed with and a remaining pressure-temperature sensor can be introduced downstream in the region of the connection point of the two evaporator branches.

In the system with the low-pressure side refrigerant collector, in addition to the pressure-temperature sensor after the refrigerant collector for leak detection, a further pressure-temperature sensor is provided after the at least two evaporators (interior evaporator, chiller), but at least as many pressure-temperature sensors according to the number of evaporators reduced by one Counting unit, so that at least one additional pressure-temperature sensor is used in a two-evaporator system. If here too it is impossible that the at least two evaporators are operated in parallel, then one pressure-temperature sensor downstream of the low-pressure side refrigerant collector can preferably be used alone. As a result, only one evaporator (chiller or indoor evaporator) is always in operation.

• 1 eine Schaltungsanordnung eines Kältemittelkreislaufs zur Durchführung eines Ausführungsbeispiels des erfindungsgemäßen Verfahrens unter Verwendung eines niederdruckseitig angeordneten Kältemittelsammlers,
• 2 eine zur Schaltungsanordnung nach 1 alternative Schaltungsanordnung zur Durchführung eines Ausführungsbeispiels des erfindungsgemäßen Verfahrens unter Verwendung eines hochdruckseitig angeordneten Kältemittelsammlers, und
• 3 eine weitere zur Schaltungsanordnung nach 1 alternative Schaltungsanordnung zur Durchführung eines Ausführungsbeispiels des erfindungsgemäßen Verfahrens ausgestattet mit einem dritten Expansionsorgan.

Further advantages, features and details of the invention emerge from the following description of preferred embodiments and from the drawings. Show:

• 1 1 shows a circuit arrangement of a refrigerant circuit for carrying out an embodiment of the method according to the invention using a refrigerant collector arranged on the low pressure side,
• 2 one according to the circuit arrangement 1 alternative circuit arrangement for carrying out an embodiment of the method according to the invention using a refrigerant collector arranged on the high-pressure side, and
• 3 another to the circuit arrangement after 1 alternative circuit arrangement for carrying out an embodiment of the method according to the invention equipped with a third expansion element.

The 1 to 3 for the sake of simplicity, each show a refrigerant circuit intended for pure AC operation (cooling operation) 10 a refrigeration system of a vehicle. The functional expansion with regard to heat pump operation was dispensed with, since the basic idea for describing the method can already be fully illustrated with the simple connection concept. These refrigerant circuits 10 are constructed in an identical basic structure and differ in the arrangement of a refrigerant collector as a low-pressure or high-pressure refrigerant collector.

• - einem Kältemittelverdichter 3,
• - einem äußeren Kondensator 4 oder Gaskühler 4, welcher mit dem Hochdruckausgang des Kältemittelverdichters 3 fluidverbunden ist,
• - einem Chiller-Zweig 1.0 mit einem zur Kühlung einer elektrischen Komponente (bspw. eine Hochvoltbatterie, eine elektrische Antriebskomponente usw.) des Fahrzeugs vorgesehenen Chiller 1, einem dem Chiller 1 vorgeschalteten und als elektrisches Expansionsventil ausgebildeten ersten Expansionsorgan AE1 und einem dem Chiller 1 nachgeschalteten ersten Druck-Temperatursensor pT1, wobei der Chiller 1 mit einem Kühlmittelkreislauf 1.1 zur Kühlung der elektrischen Komponente thermisch gekoppelt ist,
• - einem Innenraum-Verdampferzweig 2.0 mit einem Innenraum-Verdampfer 2 und einem demselben vorgeschalteten und mit einer Absperrfunktion ausgeführten zweiten Expansionsorgan AE2 wobei der Innenraum-Verdampferzweig 2.0 dem Chiller-Zweig 1.0 parallel geschaltet ist,
• - einem Kältemittelsammler 6.1 bzw. 6.2, der gemäß den 1 und 3 als Niederdruck-Kältemittelsammler 6.1 mit einem nachgeschalteten zweiten Druck-Temperatursensor pT2 dem Chiller-Zweig 1.0 und dem Innenraum-Verdampferzweig 2.0 stromabwärts nachgeschaltet ist und der gemäß 2 als Hochdruck-Kältemittelsammler 6.2 dem äußeren Kondensator 4 oder Gaskühler 4 stromabwärts nachgeschaltet ist,
• - einem inneren Wärmeübertrager 5, dessen Hochdruckseite den Kondensator 4 oder Gaskühler 4 mit dem Chiller-Zweig 1.0 und dem Innenraum-Verdampferzweig 2.0 fluidverbindet, während dessen niederdruckseitiger Abschnitt gemäß den 1 und 3 zwischen dem Niederdruck-Kältemittelsammler 6.1 und dem Kältemittelverdichter 3 in den Kältemittelkreislauf 10 und gemäß 2 zwischen dem Chiller-Zweig 1.0 und dem Kältemittelverdichter 3 eingebunden ist,
• - einem dem Kondensator 4 oder Gaskühler 4 nachgeschalteten dritten Druck-Temperatursensor pT3,
• - einem dem Kältemittelverdichter 3 nachgeschalteten vierten Druck-Temperatursensor pT4,
• - einem gemäß den 2 und 3 dem Innenraum-Verdampfer 2 stromabwärts nachgeschalteten fünften Druck-Temperatursensor pT5, und
• - einem gemäß 2 der Parallelschaltung des Chiller-Zweiges 1.0 und des Innenraumverdampfers 2.0 stromabwärts optional in Abhängigkeit der Betriebsstrategie nachgeschalteten sechsten Druck-Temperatursensor pT6.

The refrigerant circuit 10 according to the 1 to 3 consists of the following components:

• - a refrigerant compressor 3 .
• - an outer capacitor 4 or gas cooler 4 which is connected to the high pressure outlet of the refrigerant compressor 3 is fluid connected,
• - a chiller branch 1.0 with a chiller provided for cooling an electrical component (for example a high-voltage battery, an electrical drive component, etc.) of the vehicle 1 , a chiller 1 upstream and designed as an electrical expansion valve first expansion element AE1 and one the chiller 1 downstream first pressure-temperature sensor pT1 , the chiller 1 with a coolant circuit 1.1 is thermally coupled to cool the electrical component,
• - an interior evaporator branch 2.0 with an interior evaporator 2 and a second expansion element connected upstream of it and designed with a shut-off function AE2 being the interior evaporator branch 2.0 the chiller branch 1.0 is connected in parallel,
• - a refrigerant collector 6.1 respectively. 6.2 that according to the 1 and 3 as a low-pressure refrigerant collector 6.1 with a downstream second pressure-temperature sensor pT2 the chiller branch 1.0 and the interior evaporator branch 2.0 downstream and is according to 2 as a high-pressure refrigerant collector 6.2 the outer capacitor 4 or gas cooler 4 is connected downstream,
• - an internal heat exchanger 5 whose high pressure side is the condenser 4 or gas cooler 4 with the chiller branch 1.0 and the interior evaporator branch 2.0 fluidly connected, during its low-pressure side section according to 1 and 3 between the low pressure refrigerant collector 6.1 and the refrigerant compressor 3 into the refrigerant circuit 10 and according to 2 between the chiller branch 1.0 and the refrigerant compressor 3 is involved,
• - one to the capacitor 4 or gas cooler 4 downstream third pressure-temperature sensor pT3 .
• - one the refrigerant compressor 3 downstream fourth pressure-temperature sensor pT4 .
• - one according to the 2 and 3 the interior evaporator 2 downstream fifth pressure-temperature sensor pt5 , and
• - according to one 2 the parallel connection of the chiller branch 1.0 and the interior evaporator 2.0 downstream sixth pressure-temperature sensor optionally depending on the operating strategy PT6 ,

Is the high-pressure cold collector 6.2 in the capacitor 4 or gas cooler 4 is integrated, so is the third pressure-temperature sensor pT3 downstream of the capacitor 4 or gas cooler 4 provided. However, since such systems are generally systems that are intended exclusively for subcritical system operation, the third pressure-temperature sensor can pT3 omitted.

Finally, for the refrigerant circuit 10 according to the 1 to 3 an air conditioning control unit is provided as a control unit (not shown in the figures), to which input signals to be processed, such as actual values from pressure-temperature sensors, are supplied, from which control signals or setpoints are used as output signals for controlling the individual components of the refrigerant circuit 10 to create.

The interior evaporator branch 2.0 points according to the 1 and 2 a check valve 7 on. The interior evaporator branch is at this position 2.0 according to 3 with a third expansion organ AE3 educated.

First, the single-chiller operation of the refrigerant circuit 10 according to the 1 to 3 described, in which only the chiller 1 for exclusive component cooling (for example the high-voltage battery) and the interior evaporator branch 2.0 by means of the second expansion organ AE2 is blocked.

In such a single-chiller operation of the refrigerant circuit 10 according to 1 and 3 the high-pressure refrigerant flows from the refrigerant compressor 3 in the outer capacitor 4 or gas cooler 4 , then into the high pressure section of the internal heat exchanger 5 and then becomes by means of the first expansion organ AE1 in the chiller branch 1.0 relaxed. From the chiller branch 1.0 the refrigerant flows through the low-pressure refrigerant collector 6.1 and the low pressure section of the inner heat exchanger 5 back to the refrigerant compressor 3 , Here, the coolant circuit 1.1 heat transferred to the refrigerant by means of the condenser 4 or the gas cooler 4 transferred to the ambient air of the vehicle.

The low pressure refrigerant collector 6.1 of the refrigerant circuit 10 has the task of separating the gaseous and the liquid phase of the incoming refrigerant from one another and storing or circulating the liquid refrigerant in the sense of a volume buffer, depending on the amount of refrigerant required by the system. That from the low-pressure refrigerant collector 6.1 in the downstream low-pressure section of the inner heat exchanger 5 to the refrigerant compressor 3 extracted refrigerant should have the highest possible and defined vapor content. Practical values range between 80-95%. Values below this mean that the refrigerant is too wet and therefore there is a risk of oil washing out on the refrigerant compressor 3 Values above this can return the oil to the refrigerant compressor 3 affect.

Furthermore, by means of the low-pressure refrigerant collector 6.1 that of the refrigerant compressor 3 into the refrigerant circuit 10 brought in and among other things in the low-pressure refrigerant collector 6.1 stored lubricating oil back to the refrigerant compressor 3 to be led back. For this purpose, for example, in the low-pressure refrigerant collector 6.1 a U-shaped (outlet) pipe is integrated, which has an oil hole (also called a sniffer hole) at the lowest point. One open end of the U-tube extends into the vapor space of the low-pressure refrigerant collector above the liquid refrigerant 6.1 , the other (inlet) pipe leads upstream into the suction line to the chiller 1 , If the flow rate in the U-tube is sufficient, the suction effect causes oil or oil / refrigerant liquid mixture to be sucked up from the lower area of the low-pressure refrigerant collector 6.1 , Depending on the size of the inner bore, there is a steam content of, for example, 90% at the outlet of the low-pressure refrigerant collector 6.1 on. If the oil hole is too small, the steam content increases, more oil remains and oil collects in the lower area of the low-pressure refrigerant collector 6.1 on, while if the oil drilling is too large, the vapor content drops and the ejected liquid content increases.

Such a low-pressure refrigerant collector 6.1 regulates when commissioning the refrigerant circuit 10 or in the event of a load change from dual operation of the evaporator (i.e. chiller 1 and interior evaporators 2 ) on single chiller operation the steam content at the refrigerant outlet of the chiller 1 to a constant value. The one through the low-pressure refrigerant collector 6.1 The steam content set here is in the steady state of the refrigerant circuit 10 both at the outlet of the chiller 1 as well as at the refrigerant outlet of the low-pressure refrigerant collector 6.1 on. This means that the refrigerant state at the refrigerant outlet of the chiller 1 due to the explained property of the low-pressure refrigerant collector 6.1 operated on the curve of the constant vapor content (for example 90%), close to the dew line. At the same time, this means that the value of the overheating in normal system operation is zero. By means of the first expansion organ AE1 there is therefore either undercooling control by means of the third pressure-temperature sensor pT3 or control to an optimal high pressure, depending on a sub- or supercritical system operation.

The supercooling control takes place in such a way that the third pressure-temperature sensor pT3 Pressure and temperature at the outlet of the condenser 4 or gas cooler 4 recorded and the amount of hypothermia is determined from the values. If the actual value moves above the setpoint, the first expansion element opens AE1 until the setpoint is reached has been. If the actual value is less than the target value, the first expansion device AE1 closed until the setpoint is reached.

The regulation to an optimal high pressure means that the third pressure-temperature sensor pT3 Pressure and temperature at the outlet of the condenser 4 or gas cooler 4 recorded and the amount of the target high pressure is determined from the values. If the actual value moves above the setpoint, the first expansion element opens AE1 until the setpoint is reached. If the actual value is smaller than the target value, the first expansion device AE1 closed until the setpoint is reached. (!).

Is in the refrigerant circuit 10 according to 1 the function of an underfill detection by means of the second pressure-temperature sensor pT2 realized, the first pressure-temperature sensor is in single chiller mode pT1 not necessary, as at the outlet of the low-pressure refrigerant collector as stated above 6.1 and at the refrigerant outlet of the chiller 1 almost the same pressure-temperature conditions exist. In addition, the operation of the chiller 1 always strictly from the operation of another evaporator, i.e. the interior evaporator 2 separately, so can be used consistently for a refrigerant circuit 10 according to 1 on the first pressure-temperature sensor pT1 to be dispensed with. The use of this first pressure-temperature sensor pT1 is absolutely necessary if at least two evaporators, i.e. the chiller, are operated in parallel 1 and the interior evaporator 2 is provided. The minimum number of required pressure-temperature sensors downstream of the evaporators used corresponds to the number of evaporators reduced by the count 1 ,

In single chiller mode, the chiller is placed in the chiller, particularly depending on the flow temperature of the coolant 1 , in the case of regulation to hypothermia or to an optimal high pressure, significantly higher low pressures in the refrigerant circuit 10 compared to a multi-evaporator operation using the chiller 1 and the interior evaporator 2 on. Especially at high flow temperatures in the cooling water of the coolant circuit 1.1 of the chiller 1 high values are achieved in low pressure, which decrease with falling supply temperature or with an increase in the cooling request (differential temperature water supply to return). Especially when the coolant supply temperature increases at the chiller 1 the low pressure in the refrigerant circuit increases 10 on.

With the increasing low pressure of the refrigerant, its density also increases and thus leads to an increased refrigerant requirement in the low-pressure section of the refrigerant circuit 10 , ie there is a refrigerant underfill. This means that in single chiller mode, the refrigerant can flow out of the chiller 1 no longer operate in the two-phase area of the refrigerant and thus close to the dew line when the low-pressure refrigerant collector 6.1 empty, i.e. can no longer supply refrigerant and its reservoir has been exhausted. The low pressure refrigerant collector 6.1 empties, there is an increasing overheating of the refrigerant at the refrigerant outlet of the chiller 1 , and thus also at the outlet of the low-pressure refrigerant collector 6.1 ,

With the increasing density of the refrigerant and thus the mass flow, there can also be a torque overload on the refrigerant compressor 3 occur.

As soon as such a torque overload of the refrigerant compressor 3 and / or an increasing overheating of the refrigerant at the refrigerant outlet of the chiller 1 by means of the first pressure-temperature sensor pT1 (or possibly by means of the second pressure-temperature sensor pT2 ) is detected, takes place through a control intervention on the refrigerant compressor designed as an electric compressor 3 a lowering of the low pressure by the speed of the refrigerant compressor 3 and thus the cooling capacity is adjusted. The low pressure is reduced depending on the ambient conditions and the load on the chiller 1 , ie the low pressure in the system is reduced until the problem of overheating or torque is no longer detected. With this limitation of the maximum permissible low pressure upwards, the degree of freedom of the low pressure, namely to increase in any way, is restricted.

The detection of the torque overload of the refrigerant compressor 3 is carried out by self-diagnosis when the refrigerant compressor 3 is designed as an electric refrigerant compressor. For this purpose, a corresponding diagnostic signal is provided by such an electrical refrigerant compressor, which is evaluated by a control unit, for example an air conditioning control unit.

Another negative characteristic that can occur in connection with increasing overheating is the deterioration in the return of oil to the refrigerant compressor 3 , because the oil is now increasing in the low-pressure refrigerant collector 6.1 is stored and due to the lack of liquid refrigerant phase with which the oil mixes, the transport medium to the refrigerant compressor 3 is no longer available

Alternatively, the low pressure is controlled by controlling the refrigerant compressor 3 limited to a maximum low pressure value, so that a further increase in the low pressure at the refrigerant outlet of the chiller 1 is prevented. The maximum The low pressure value depends on the ambient conditions and the cooling capacity of the chiller 1 fixed, ie the evaporation temperature should start when the refrigerant circuit starts 10 a value below the ambient temperature can be set or initially based on this and with the duration of operation again taking into account the values on the first pressure / temperature sensor pT1 the efficiency-optimal operating point are approached.

With the reduction of the low pressure, the evaporation temperature of the refrigerant in the chiller 1 reduced. The cooling capacity of the chiller generated before the low pressure was reduced 1 restore, is through a cooperation of refrigerant compressors 3 and the first expansion organ AE1 this cooling capacity is reset by increasing the stroke or speed and moving the first expansion device AE1 , ie usually reacting to the new boundary conditions by further throttling. It has to be taken into account that there can be situations in which the system can work independently of the supercooling regulation or regulation of the optimal high pressure. and must, otherwise an excess cooling capacity cannot be avoided. The efficient control of the refrigerant circuit before lowering the low pressure 10 by means of the supercooling control or the control of the optimal high pressure, it is therefore suspended until, in particular, due to changed, but especially lower, coolant flow temperatures at the chiller 1 new low pressure levels are set and this enables the return to efficient system operation, ie the refrigerant compressor 3 provides the stroke or the amount of coolant cooling, the first expansion element AE1 sets the subcooling or the optimal high pressure ..

In a single-chiller operation of the refrigerant circuit 10 according to 2 the high-pressure refrigerant flows from the refrigerant compressor 3 in the outer capacitor 4 or gas cooler 4 , then into the high-pressure refrigerant collector 6.2 and then into the high pressure section of the internal heat exchanger 5 to then by means of the first expansion device AE1 in the chiller branch 1.0 to be relaxed. From the chiller branch 1.0 the refrigerant flows over the low pressure section of the internal heat exchanger 5 back to the refrigerant compressor 3 , Here, the coolant circuit 1.1 heat transferred to the refrigerant together with the energy introduced on the compressor side by means of the condenser 4 or the gas cooler 4 transferred to the ambient air of the vehicle.

The condenser 4 can also with integrated high-pressure refrigerant collector 6.2 usually follows the high-pressure refrigerant collector 6.2 downstream there is a supercooling section consisting of a few flat tubes and integrated into the ambient heat exchanger, at the outlet of which the downstream section of the inner heat exchanger is located 5 followed.

In this single chiller mode, overheating occurs at the refrigerant outlet of the chiller 1 in a refrigerant circuit 10 according to 2 also operated close to the dew line of the refrigerant by overheating to a value between 3 and 5 K by means of the first expansion device AE1 is regulated, the degree of overheating by means of the first pressure-temperature sensor pT1 is detected. With a maximum cooling capacity requirement for the chiller 1 becomes the first expansion element designed as an electrical expansion valve AE1 set to a minimum, but still safe, detectable overheating value.

In single chiller mode, this type of control results in significantly higher low pressures in the refrigerant circuit 10 compared to a multi-evaporator operation using the chiller 1 and the interior evaporator 2 on. Especially when the coolant flow temperature increases at the inlet of the chiller 1 the low pressure in the refrigerant circuit increases 10 on.

With the increasing low pressure of the refrigerant, its density also increases and thus leads to an increased refrigerant requirement in the low-pressure section of the refrigerant circuit, ie there is an underfill of the refrigerant. This means that in single chiller mode, the refrigerant can flow out of the chiller 1 can no longer be operated close to the dew line because the refrigerant underfill means that the refrigerant overheats at the refrigerant outlet of the chiller 1 occurs.

With the increasing density of the refrigerant, there can also be a torque overload on the refrigerant compressor 3 occur.

As soon as such a torque overload of the refrigerant compressor 3 and / or an increasing overheating of the refrigerant at the refrigerant outlet of the chiller 1 by means of the first pressure-temperature sensor pT1 is detected, takes place through a control intervention on the refrigerant compressor designed as an electric compressor 3 a lowering of the low pressure by the speed of the refrigerant compressor 3 and thus the cooling capacity is reduced. The low pressure is reduced depending on the ambient conditions and the load on the chiller 1 , ie the low pressure in the system reduced until the overheating phenomenon and / or the torque overload are no longer detected. By limiting the maximum permissible low pressure upwards, the degree of freedom of the low pressure to increase in any way is restricted.

At the outlet of the interior evaporator 2 is the pressure-temperature sensor pt5 the overheating control of the refrigerant at the outlet of the interior evaporator is responsible for this 2 to monitor.

The detection of the torque overload of the refrigerant compressor 3 is carried out by self-diagnosis when the refrigerant compressor 3 is designed as an electric refrigerant compressor. For this purpose, a corresponding diagnostic signal is provided by such an electrical refrigerant compressor, which is evaluated by a control unit, for example an air conditioning control unit.

Alternatively, the low pressure is controlled by controlling the refrigerant compressor 3 limited to a maximum low pressure value, so that a further increase in the low pressure at the refrigerant outlet of the chiller 1 is prevented. The maximum low pressure value depends on the ambient conditions and the cooling capacity of the chiller 1 fixed, ie the evaporation temperature should start when the refrigerant circuit starts 10 a value below the ambient temperature can be set or initially based on this and with the duration of operation again taking into account the values on the first pressure / temperature sensor pT1 the efficiency-optimal operating point are approached.

With the reduction of the low pressure, the evaporation temperature of the refrigerant in the chiller 1 reduced. The cooling capacity of the chiller generated before the low pressure was reduced 1 restore, is through a cooperation of refrigerant compressors 3 and the first expansion organ AE1 this cooling capacity is reset by increasing the stroke or speed and moving the first expansion device AE1 , ie usually reacting to the new boundary conditions by further throttling. It should be taken into account that there can be situations in which the system can and must work independently of the supercooling control or the control of the optimal high pressure, otherwise an excess cooling capacity cannot be avoided. The efficient control of the refrigerant circuit before lowering the low pressure 10 by means of the supercooling control or the control of the optimal high pressure, it is therefore suspended until, in particular, due to changed, but especially lower, coolant flow temperatures at the chiller 1 new low pressure levels are set and this enables the return to efficient system operation, ie the refrigerant compressor 3 provides the stroke or amount of coolant cooling, the first expansion organ AE1 sets the subcooling or the optimal high pressure.

It should be added that in the case of the always separate operation of Chiller 1 and interior evaporators 2 , ie both heat exchangers are never operated simultaneously, the two pressure-temperature sensors pT1 and pt5 omitted and by a pressure-temperature sensor PT6 downstream of the node of the chiller branch 1.0 and the interior evaporator branch 2.0 can be replaced.

Another advantage of the method according to the invention for lowering the low pressure when a torque overload is detected on the refrigerant compressor 3 and / or an increasing overheating of the refrigerant at the refrigerant outlet of the chiller 1 is not only to avoid switching off the refrigerant compressor 3 in the event of a torque overload, but also in ensuring the oil transport and adequate lubrication of the refrigerant compressor 3 and thus also an increased component life of the refrigerant compressor 3 ,

Finally, the method according to the invention also operates the refrigerant circuit 10 avoided in the area of a critical filling quantity in terms of a potential refrigerant underfilling.

That in the 1 and 2 the interior evaporator 2 downstream check valve 7 prevents the refrigerant from shifting into the interior evaporator in single chiller mode 2 , With the refrigerant circuit 10 according to 3 The third expansion organ takes on this function AE2 , The following is a multi-evaporator operation, i.e. a parallel operation of the chiller 1 and the interior evaporator 2 the refrigerant circuits 10 according to the 1 to 3 described.

In such a multi-evaporator operation, the interior evaporator 2 to the reference variable of the refrigeration process and specifies the level of the low pressure and thus the required evaporation temperature. With a refrigerant circuit 10 according to 1 this means that using the low pressure refrigerant collector 6.1 a certain constant vapor content at the outlet of the low-pressure refrigerant collector 6.1 and thus also at the refrigerant outlet of the interior evaporator 2 is set. By means of the first expansion organ AE1 is always an overheating depending on the power requirement or a minimum overheating for maximum Power at the refrigerant outlet of the chiller 1 to set a particular chiller 1 flowing refrigerant mass flow is set, so that a defined cooling of the water temperature of the coolant circuit 1.1 to achieve.

Even with the refrigerant circuit 10 with the high pressure refrigerant collector 6.2 is about the first expansion organ AE1 of the chiller 1 A defined cooling of the water temperature is regulated by the chiller 1 flowing refrigerant mass flow is set.

Alternatively, the refrigerant circuit 10 according to 1 also with a third expansion organ AE3 operated like this 3 shows. This third expansion organ AE3 belongs to the interior evaporator branch 2.0 and is the interior evaporator 2 downstream downstream. The refrigerant condition within the interior evaporator branch 2.0 can via a downstream of the interior evaporator 2 provided pressure-temperature sensor pt5 can be detected, alternatively one can also use the interior evaporator 2 downstream air temperature _sensors T _{Luft_} can be used for this.

This third expansion element, which is designed as an electrically or mechanically controllable expansion valve AE3 ensures that in the interior evaporator branch 2.0 there is no drop below a low pressure leading to icing.

This can be used in the interior evaporator branch 2.0 a medium pressure level can be set while on the chiller 1 any low pressure level below the low pressure level in the evaporator branch 2.0 by means of the refrigerant compressor 3 depending on the required cooling capacity of the chiller 1 is set. This is done by means of the first expansion element AE1 the overheating at the refrigerant outlet of the chiller 1 set, which reduces the cooling capacity of the chiller 1 depending on the degree of overheating at the refrigerant outlet of the chiller 1 is variable at the prevailing low pressure. This is the maximum cooling capacity of the chiller 1 achieved when the refrigerant is set at the refrigerant outlet near the dew line of the refrigerant.

At one compared to the low pressure of the interior evaporator 2 smaller low pressure of the chiller 1 is used to increase the cooling capacity of the chiller 1 the refrigerant at the refrigerant outlet of the chiller 1 close to its dew line, ie operated with a slight overheating and the interior evaporator 2 by means of the third expansion organ AE3 operated at a medium pressure level. To reduce the cooling capacity of the chiller 1 is controlled by the refrigerant compressor 3 the low pressure of the chiller 1 down to the low pressure of the interior evaporator 2 raised. By further throttling the first expansion element AE1 can also reduce the cooling capacity on the chiller 1 be reduced.

At a low pressure of the interior evaporator 2 corresponding low pressure of the chiller 1 becomes a maximum cooling capacity on the chiller 1 generated when the refrigerant in the refrigerant outlet of the chiller 1 is operated close to its dew line, i.e. with minimal overheating. The cooling capacity of the chiller 1 is achieved by increasing the superheat of the refrigerant using the first expansion element AE1 at constant pressure in the interior evaporator 2 reduced.

With a refrigerant circuit 10 according to the 1 to 3 At least one further interior evaporator can be used, for example as a rear evaporator, which is kept at an intermediate pressure level by means of a separate, electrically or mechanically adjustable expansion valve. However, it is particularly advantageous to have this further expansion element upstream of the second expansion element AE2 of the interior evaporator 2 to tie.

With the refrigerant circuit 10 according to the 1 to 3 can instead of the first expansion element designed as an electrical expansion valve AE1 in single-chiller mode, this can also be designed as a switchable thermal expansion element or as a switchable orifice tube with a defined opening cross-section. The exact setting of the coolant temperature of the coolant circuit 1.1 of the chiller 1 must therefore be set by means of a cyclical operation of the expansion device around the setpoint of the coolant expression temperature on the chiller.

In connection with the high pressure refrigerant collector 6.2 it should be noted that the collector bottle also in the condenser 4 can be integrated before downstream into the capacitor 4 flow through the integrated subcool section. In this constellation, which cannot be used in this construction for the execution as an air heat pump, the third pressure-temperature sensor can pT3 omitted because of the capacitor 4 in which high-pressure refrigerant collector 6.2 and subcooling are integrated, subcooling of the refrigerant is automatically set.

Furthermore, the methods described can also be used in a refrigerant circuit 10 can be realized with a heat pump function.

Finally, the methods described for all known refrigerants, such as R744 . R134a . 1234yf etc. are used, especially for the R744 system only the low-pressure refrigerant collector 6.1 Takes into account.

LIST OF REFERENCE NUMBERS

1

Chiller of the refrigerant circuit 10

1.0

Chiller branch

1.1

Coolant circuit of the chiller 1

2

Interior evaporator

2.0

Interior evaporator branch

3

Refrigerant compressor

4

Condenser or gas cooler

5

internal heat exchanger

6.1

Low-pressure refrigerant collector

6.2

High-pressure refrigerant collector

7

check valve

10

Refrigerant circulation

AE1

first expansion organ

AE2

second expansion organ

AE3

third expansion organ

pT1

Pressure-temperature sensor

pT2

Pressure-temperature sensor

pT3

Pressure-temperature sensor

pT4

Pressure-temperature sensor

pt5

Pressure-temperature sensor

PT6

Pressure-temperature sensor

T _air

Air temperature sensor

QUOTES INCLUDE IN THE DESCRIPTION

This list of documents listed by the applicant has been generated automatically and is only included for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Patent literature cited

• DE 102017108809 A1 [0003]
• DE 102016108468 A1 [0003]
• DE 102009015658 A1 [0003]
• DE 102016117075 A1 [0004]
• DE 102014001022 A1 [0005]
• DE 102009021530 A1 [0006]
• DE 102011118162 B4 [0007]

Claims (10)

Method for operating a refrigerant circuit (10) of a refrigeration system of a vehicle a chiller branch (1.0) which has a chiller (1), a first expansion element (AE1) and a first pressure-temperature sensor (pT1) connected downstream of the chiller (1) and is thermally coupled to a coolant circuit (1.1), - at least one interior evaporator branch (2.0), which has an interior evaporator (2) and a second expansion element (AE2) and is connected in parallel to the chiller branch (1.0), - A refrigerant compressor (3), and - A condenser or gas cooler (4), wherein - In a single chiller mode, the operating point of the refrigerant circuit (10) at the refrigerant outlet of the chiller (1) is set near the dew line of the refrigerant, - The low pressure and the associated temperature of the refrigerant is detected by means of the first pressure-temperature sensor (pT1) of the chiller (1), and - The low pressure is limited by controlling the refrigerant compressor (3) to a maximum low pressure value which is dependent on ambient conditions and the required cooling capacity of the chiller (1) or is reduced while reducing the cooling capacity on the chiller (1) if a torque overload on the refrigerant compressor (3) or a predetermined deviation of the temperature from the dew line of the refrigerant is detected at the refrigerant outlet of the chiller (1). Procedure according to Claim 1 , in which, after the lowering of the low pressure, the cooling capacity at the chiller (1) is adjusted to the target cooling capacity by means of a control of the first expansion element (AE1) together with the refrigerant compressor (3). Procedure according to Claim 1 or 2 , in which - the refrigerant circuit (10) is designed with a low-pressure refrigerant collector (6.1), with which defined refrigerant vapor contents can be set, and - the refrigerant for adjustment to its dew line or close to the dew line in the two-phase region of the refrigerant by means of Low-pressure refrigerant collector (6.1) is set to a degree of overheating of 0 K. Procedure according to Claim 1 , in which - the refrigerant circuit (10) is designed with a high-pressure refrigerant collector (6.2), and - the refrigerant is set to or near its dew line by means of the first first expansion element (AE1) to a degree of overheating with a value between 3 and 5 K. is regulated. Method according to one of the preceding claims, in which a third expansion element (AE3) is connected downstream of the interior evaporator (2) in a chiller and evaporator operation, wherein - The interior evaporator (2) is operated at a medium pressure level, and - The chiller (1) is operated at a low pressure level depending on the requested cooling capacity by regulating the refrigerant compressor (3) and the first expansion element (AE1). Procedure according to Claim 5 , in the case of which the chiller (1) has a lower pressure than the low pressure of the interior evaporator (2) to increase the cooling capacity of the chiller (1) - the refrigerant state at the refrigerant outlet of the chiller (1) is set close to its dew line, and - the interior evaporator (2) is operated at a medium pressure level by means of the third expansion element (AE3). Procedure according to Claim 5 or 6 , in which to reduce the cooling capacity of the chiller (1) by regulating the refrigerant compressor (3) the low pressure of the chiller (1) is raised to the low pressure of the interior evaporator (2). Procedure according to one of the Claims 5 to 7 , in which a maximum cooling capacity at the chiller (1) is generated at a low pressure of the chiller (1) corresponding to the low pressure of the interior evaporator (2) if the condition of the refrigerant at the refrigerant outlet of the chiller (1) is set close to its dew line , Procedure one of the Claims 5 to 8th , in which, at a low pressure of the chiller (1) corresponding to the low pressure of the interior evaporator (2), the cooling capacity of the chiller (1) by increasing the superheating of the refrigerant by means of the first expansion element (AE1) at constant pressure in the interior evaporator ( 2) is reduced. Procedure according to one of the Claims 5 to 9 , in which, when the interior evaporator (2) or the chiller (1) is operated exclusively at an identical low pressure level, only one pressure-temperature sensor (pT6) is arranged downstream of the chiller branch (1.0) and the interior evaporator branch (2.0) ,

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