DE102020117133A1 - Method for operating a refrigeration system of a motor vehicle and refrigeration system with backflow prevention - Google Patents

Abstract

A method (500) for operating a refrigeration system (10) for a motor vehicle is described, the refrigeration system (10) having:a refrigerant compressor (12) which can be or is connected to a primary line (14);at least one evaporator (18, 22) which is arranged in the primary line (14);a chiller (28) which is arranged in a chiller branch (28.1, 28.3) which is fluidically parallel to the evaporator (18, 22), the chiller (28) in the chiller branch (28.1) an expansion element (AE1) is assigned and the chiller (28) is connected to a coolant circuit (28.2) that is separate from the coolant circuit (11);wherein the method comprises the following steps:routing coolant from the coolant compressor (12) to the evaporator (18 , 22) so that it is charged with refrigerant and up to the expansion element (AE1) of the chiller branch; and if the temperature (Tcool) of the coolant is lower than the temperature of the refrigerant (Tcool) (S503): repeated opening and closing (S504) of the expansion element (AE1) assigned to the chiller (28), such that downstream of the chiller (28) refrigerant sucked in from the low-pressure-side connection (22.2) between the evaporator (22) and refrigerant compressor (12) is flushed out of the chiller (28).

Description

• einen Kältemittelverdichter, der mit einem Primärstrang verbindbar oder verbunden ist;
• wenigstens einen Verdampfer, der im Primärstrang angeordnet ist;
• einen Chiller, der in einem zum Verdampfer strömungstechnisch parallelen Chillerzweig angeordnet ist, wobei dem Chiller im Chillerzweig ein Expansionsorgan zugeordnet ist und wobei der Chiller mit einem von dem Kältemittelkreislauf gesonderten Kühlmittelkreislauf verbunden ist;
• wobei bei dem Verfahren Kältemittel vom Kältemittelverdichter zu dem Verdampfer geleitet wird, so dass dieser mit Kältemittel beaufschlagt ist, und bis zu dem Expansionsorgan des Chillerzweigs geleitet wird.

The invention relates to a method for operating a refrigeration system for a motor vehicle, the refrigeration system having:

• a refrigerant compressor which is connectable or connected to a primary line;
• at least one evaporator which is arranged in the primary line;
• a chiller which is arranged in a chiller branch that is fluidically parallel to the evaporator, an expansion element being assigned to the chiller in the chiller branch and the chiller being connected to a coolant circuit separate from the refrigerant circuit;
• wherein, in the method, refrigerant is passed from the refrigerant compressor to the evaporator, so that refrigerant is applied to it, and is passed as far as the expansion element of the chiller branch.

From the DE 10 2018 209 769 A1 a method for operating a refrigeration system without a heating register for an electric vehicle is known.

From the DE 10 2011 118 162 A1 a refrigeration system with a chiller and heating register is known.

Furthermore, the DE 10 2012 108 731 A1 and the WO 2010/003484 A1 pointed out, who also deal with refrigeration systems.

With refrigeration systems, especially with those with a heat pump function, the case often occurs that inactive system sections are present in the refrigeration system both in cooling operation (AC operation) and in a respective heat pump operation, through which refrigerant does not flow in a respectively activated circuit.

If the refrigeration system is connected and operated in a cooling mode (AC mode), for example, a chiller branch and / or a rear evaporator branch and / or a heating branch cannot have refrigerant flowing through it.

In a heat pump process, for example, a front evaporator branch and / or a rear evaporator branch and / or a chiller branch and / or a branch with an external heat exchanger (condenser or gas cooler branch) cannot have refrigerant flowing through it.

If a medium flows through or against inactive components of the refrigeration system, for example water as the coolant in the coolant circuit of the chiller (battery cooling and / or electric motor cooling), the temperature of the medium can be lower than the evaporation temperature set in the refrigeration system or in the system. The corresponding component thus forms a kind of cold point in the refrigeration system, with gaseous refrigerant being sucked in or flowing there, condensed and removed. The condensed refrigerant is thus withdrawn from the active process on this cold component and is no longer available. Under certain circumstances, this can lead to underfilling of components in the actively connected refrigerant circuit or process, so that optimal operation of the refrigeration system in the desired mode (AC operation, heat pump operation) is not possible. Furthermore, with the relocation of refrigerant, oil bound in the refrigerant can also be relocated and withdrawn from the active process.

The object on which the invention is based is seen in specifying a method for operating a refrigeration system and a refrigeration system, the above disadvantages being to be avoided.

This object is achieved by a method and by a refrigeration system with the features of the respective independent claims. Advantageous configurations with expedient developments are specified in the dependent claims.

• einen Kältemittelverdichter, der mit einem Primärstrang verbindbar oder verbunden ist;
• wenigstens einen Verdampfer, der im Primärstrang angeordnet ist;
• einen Chiller, der in einem zum Verdampfer strömungstechnisch parallelen Chillerzweig angeordnet ist, wobei dem Chiller im Chillerzweig ein Expansionsorgan zugeordnet ist und wobei der Chiller mit einem von dem Kältemittelkreislauf gesonderten Kühlmittelkreislauf verbunden ist; und
• ein zwischen dem Kältemittelverdichter und dem Heizregister angeordnetes Sekundärstrangventil. Dabei umfasst das Verfahren folgende Schritte:
  • Leiten von Kältemittel vom Kältemittelverdichter zu dem Verdampfer, so dass dieser mit Kältemittel beaufschlagt ist, und bis zu dem Expansionsorgan des Chillerzweigs;
  • wenn die Temperatur des Kühlmittels tiefer ist als die Temperatur des Kältemittels: wiederholtes Öffnen und Schließen des dem Chiller zugeordneten Expansionsorgans, derart dass stromabwärts des Chillers aus der niederdruckseitigen Verbindung zwischen Verdampfer und Kältemittelverdichter angesaugtes Kältemittel aus dem Chiller gespült wird.

According to a first aspect, a method for operating a refrigeration system for a motor vehicle is proposed, the refrigeration system having:

• a refrigerant compressor which is connectable or connected to a primary line;
• at least one evaporator which is arranged in the primary line;
• a chiller which is arranged in a chiller branch that is fluidically parallel to the evaporator, an expansion element being assigned to the chiller in the chiller branch and the chiller being connected to a coolant circuit separate from the refrigerant circuit; and
• a secondary branch valve arranged between the refrigerant compressor and the heating register. The process comprises the following steps:
  • Conducting refrigerant from the refrigerant compressor to the evaporator, so that this is acted upon with refrigerant, and up to the expansion element of the chiller branch;
  • if the temperature of the coolant is lower than the temperature of the refrigerant: repeated opening and closing of the expansion element associated with the chiller, such that downstream of the chiller from the low-pressure side connection between the evaporator and the refrigerant compressor, refrigerant sucked in is flushed out of the chiller.

Repeated opening and closing, which can also be referred to as clocked opening / closing, enables the refrigerant and oil contained in the refrigerant to be flushed out of the chiller cyclically, even if the chiller branch is not actively flowed through by refrigerant during the relevant operating state of the refrigeration system . Thus, in addition to the maximum amount of refrigerant, the optimal and required amount of oil in the refrigerant circuit or the refrigeration system (system) is active, so that the refrigerant / oil can be avoided in inactive areas, i.e. pipe segments or sectors through which there is no active flow. A clocked opening / closing can take place at a clock frequency that is advantageous for a flushing process.

The at least one evaporator can be a heat exchanger that conditions the cabin air. The or one of the evaporators can also serve as a heat exchanger for operating a heat pump, such as an air heat pump, for absorbing heat bound in the ambient air. Depending on the design and topology of the systems or refrigeration system, the positions of the respective evaporators of an AC operation or an air heat pump operation may differ, but not their basic function in the respective operation.

• wenigstens einen Verdampfer, der im Primärstrang angeordnet ist;
• einen Chiller, der in einem zum Verdampfer strömungstechnisch parallelen Chillerzweig angeordnet ist, wobei dem Chiller im Chillerzweig ein Expansionsorgan zugeordnet ist und wobei der Chiller mit einem von dem Kältemittelkreislauf gesonderten Kühlmittelkreislauf verbunden ist;
• Dabei umfasst das Verfahren folgende Schritte:
  • Leiten von Kältemittel vom Kältemittelverdichter zu dem Verdampfer, so dass dieser mit Kältemittel beaufschlagt ist, und bis zu dem Expansionsorgan des Chillerzweigs;
  • wenn die Temperatur des Kühlmittels tiefer ist als die Temperatur des Kältemittels: Schließen bzw. geschlossen Halten des dem Chiller zugeordneten Expansionsventils und Erwärmen des Kühlmittels im Chiller mittels des Kühlmittelkreislaufs auf eine Temperatur die größer ist die Temperatur des Kältemittels, derart dass im Chiller befindliches Kältemittel auf eine Temperatur-/Druckniveau gebracht wird, das eine Rückströmung von Kältemittel aus der niederdruckseitigen Verbindung zwischen Verdampfer und Kältemittelverdichter verhindert.

According to a second aspect, which can also be understood in addition to the first aspect, a method for operating a refrigeration system for a motor vehicle is proposed, the refrigeration system having: a refrigerant compressor which can be or is connected to a primary line;

• at least one evaporator which is arranged in the primary line;
• a chiller which is arranged in a chiller branch that is fluidically parallel to the evaporator, an expansion element being assigned to the chiller in the chiller branch and the chiller being connected to a coolant circuit separate from the refrigerant circuit;
• The process comprises the following steps:
  • Conducting refrigerant from the refrigerant compressor to the evaporator, so that this is acted upon with refrigerant, and up to the expansion element of the chiller branch;
  • If the temperature of the coolant is lower than the temperature of the coolant: Close or keep the expansion valve assigned to the chiller closed and heat the coolant in the chiller by means of the coolant circuit to a temperature that is higher than the temperature of the coolant, so that the coolant in the chiller is released a temperature / pressure level is brought that prevents a backflow of refrigerant from the low-pressure side connection between the evaporator and the refrigerant compressor.

When the expansion valve is closed, refrigerant is no longer actively flowing through the chiller. Correspondingly, the refrigerant in the chiller can be heated and evaporated again by means of the warmer coolant, so that the refrigerant is not stored due to the changing temperature and pressure conditions and a backflow from the low-pressure side connection between the evaporator and the refrigerant compressor is prevented. This process step can also be combined with the above-described repeated opening and closing of the expansion valve; in particular, such an opening / closing or clocked actuation of the expansion valve can be carried out after the refrigerant has been warmed up in the meantime (with the expansion valve closed for a longer period of time).

In the method, refrigerant can be conducted from the refrigerant compressor to the evaporator and / or to the chiller branch via a heat exchanger representing a heat source. Such a heat exchanger can be designed as a condenser or gas cooler, which can transfer heat to the environment or the cabin supply air flow in a direct or indirect manner.

• wenigstens einem Verdampfer, der im Primärstrang angeordnet ist;
• einem Chiller, der in einem zum Verdampfer strömungstechnisch parallelen Chillerzweig angeordnet ist, wobei dem Chiller im Chillerzweig ein Chiller-Expansionsorgan zugeordnet ist und wobei der Chiller mit einem von dem Kältemittelkreislauf gesonderten Kühlmittelkreislauf verbunden ist.

A refrigeration system for a motor vehicle is also proposed with a refrigerant compressor which can be or is connected to a primary line;

• at least one evaporator which is arranged in the primary line;
• a chiller which is arranged in a chiller branch fluidically parallel to the evaporator, a chiller expansion element being assigned to the chiller in the chiller branch and the chiller being connected to a coolant circuit separate from the refrigerant circuit.

It is provided that a check valve is arranged in the chiller line downstream of the chiller and upstream of a connection node with a low-pressure connection that extends between the evaporator and the refrigerant compressor.

Such a check valve can prevent refrigerant from being active when inactive flowed through chiller is sucked into the chiller branch and stored there or can no longer flow back after suction from the chiller

In the refrigeration system, a check valve or an expansion element on the low-pressure side can be arranged downstream of the evaporator and upstream of the connection node. A check valve can prevent refrigerant from getting back into the evaporator and being stored there when there is little or no active flow through the evaporator, for example when the refrigerant circuit is completely routed via the chiller. Using an optional expansion valve, the system can be operated on the low-pressure side in two low-pressure positions. The evaporator can, for example, be operated at an evaporator pressure level so that the air flowing into the evaporator is at 2 ° C. or more is cooled in order to counteract icing of the evaporator.

In the refrigeration system, a section of the chiller branch upstream of the connection node, starting from the connection node and rising relative to the low-pressure connection, can be designed. Such an inclined design of the chiller branch can prevent gravity-assisted oil storage in the chiller branch.

The rising section of the chiller branch can project upwards at an angle of 30 ° to 90 ° relative to the imaginary plane in relation to an imaginary plane in which the low-pressure connection runs.

The refrigeration system can have at least one heat exchanger representing a heat source. Such a heat exchanger can be designed as a condenser or gas cooler, which can transfer heat to the environment or the cabin supply air flow in a direct or indirect manner.

The refrigeration system can also have: a secondary line, to which the refrigerant compressor can be or is connected; a heat exchanger, in particular a heating register, which is arranged in the secondary branch; and a secondary branch valve arranged between the refrigerant compressor and the heat exchanger.

The refrigeration system with a structure described above or a construction described above can also be set up to carry out the method described above.

In one embodiment of the refrigeration system with a secondary line and heat exchanger (heating register), the two methods described above can also have the following step: opening the secondary line valve so that refrigerant is conducted from the refrigerant compressor to the heating register and downstream of the heating register to the evaporator and / or to the chiller branch .

A motor vehicle can be designed with such a refrigeration system.

• 1 ein schematisches und vereinfachtes Schaltbild einer Kälteanlage für ein Kraftfahrzeug;
• 2 ein schematisches und vereinfachtes Schaltbild einer modifizierten Kälteanlage für ein Kraftfahrzeug;
• 3 ein Flussdiagram einer beispielhaften Umsetzung des Nachheizverfahrens, insbesondere mittels der in den 1 und 2 beschriebenen Kälteanlage.

Further advantages and details of the invention emerge from the following description of embodiments with reference to the figures. It shows:

• 1 a schematic and simplified circuit diagram of a refrigeration system for a motor vehicle;
• 2 a schematic and simplified circuit diagram of a modified refrigeration system for a motor vehicle;
• 3 a flowchart of an exemplary implementation of the post-heating process, in particular by means of the 1 and 2 described refrigeration system.

In 1 is an embodiment of a refrigeration system 10 for a motor vehicle shown schematically and simplified. The refrigeration system 10 includes a refrigerant circuit 11th , which can be operated both in a refrigeration system operation (also called AC operation for short) and in a heat pump mode. The refrigeration system 10 comprises in the embodiment shown a refrigerant compressor 12th , an external heat exchanger 18th , an optional internal heat exchanger 20th , a vaporizer 22nd and an accumulator or refrigerant collector 24 . The external heat exchanger 18th can be designed as a condenser or gas cooler.

The vaporizer 22nd is shown here as an example as a front evaporator for a vehicle. The vaporizer 22nd also represents other evaporators that are possible in a vehicle, such as rear evaporators, which can be arranged fluidically parallel to one another. In other words, the refrigeration system includes 10 so at least one vaporizer 22nd .

Downstream of the compressor 12th is a shut-off valve A4 arranged. Upstream of the evaporator 22nd an expansion valve AE2 is provided.

In the context of this description, in the entire refrigerant circuit 11th the refrigeration system 10 the section from the compressor 12th to the external heat exchanger 18th , to the internal heat exchanger 20th and to the evaporator 22nd as the primary strand 14th designated.

The refrigeration system 10 further comprises a heating register 26th (also known as heating condenser or heating gas cooler). Upstream of the heating register 26th is a shut-off valve A3 ,. downstream of the heating register 26th a check valve R4 arranged.

In the context of this description, in the entire refrigerant circuit of the refrigeration system 10 the section from the compressor 12th to the heating register 26th , to the check valve R4 as a secondary strand 16 designated. The secondary strand 16 includes a heating branch extending from the shut-off valve A3 via the heating register 26th to branch Ab4.

The refrigeration system 10 includes another evaporator or chiller 28 . The chiller 28 is fluidically parallel to the evaporator 22nd intended. The chiller 28 can be used, for example, to cool an electrical component of the vehicle, but also to implement a water heat pump function using the waste heat from at least one electrical component. The chiller 28 an expansion valve AE1 is connected upstream.

The low-pressure side extends between the chiller 28 and a branch Ab2 a chiller line 28.3 . The chiller strand 28.3 opens into the connection on the low pressure side at junction Ab2 22.2 that are between the evaporator 22nd and the refrigerant compressor 12th extends. In the embodiment shown here with a low-pressure refrigerant collector 24 is branch Ab2 between the evaporator 22nd and the low pressure refrigerant receiver 24 arranged.

To in the Chillerstrang 28.3 a backflow of refrigerant from the connection on the low pressure side 22.2 to prevent is in the chiller line 28.1 a check valve R5 arranged. The check valve R5 can be based on the length of the chiller line 28.3 closer to branch Ab2 than to the chiller 28 be arranged. In particular, the check valve R5 be arranged as close as possible to the branch Ab2, for example a few centimeters, in particular about 2 cm to 15 cm away from the branch Ab2.

A section 28.4 of the chiller line 28.3 can upstream of the branch Ab2 starting from the branch Ab2 and relative to the low-pressure connection 22.2 be executed rising. The ascending section 28.4 of the chiller line 28.3 based on an imaginary plane in which the low-pressure connection 22.2 extends, protrude upwards at an angle of 30 ° to 90 ° relative to the imaginary plane.

It should be noted that in the case of an ascending section 28.4 in the chiller line 28.3 the check valve R5 can also be omitted.

In this respect, the ascending section represents 28.4 in the chiller line 28.3 also represent an independent aspect of the present application.

Downstream of the evaporator 22nd and upstream of the connection node Ab2 can be in the connection 22.2 a check valve R1 be provided. Alternatively, instead of the check valve R1 a low-pressure side expansion element AE5 is arranged. The check valve R1 and the expansion valve AE5 are therefore in the 1 shown in dashed lines because they each represent an optional configuration.

Through the check valve R5 it can be prevented that refrigerant is usually not actively flowing through the evaporator 22nd , for example when the refrigerant circuit 11th completely through the chiller 28 back into the evaporator 22nd arrives and is outsourced there. Using an optional expansion valve AE5, the system can be operated on the low-pressure side in two low-pressure positions. The evaporator can 22nd for example, operated at an evaporator pressure level, so that on the evaporator 22nd incoming air to 2 ° C. or more is cooled to prevent the evaporator from icing up 22nd to counteract this as part of a dehumidification operation.

In 2 is a compared to 1 modified embodiment of a refrigeration system 10 for a motor vehicle shown schematically and simplified. In particular, the external heat exchanger 18th bidirectional flow in the embodiment shown. Unlike in the embodiment of the 1 is downstream of the heating register 26th a shut-off valve A1 arranged. The shut-off valve A1 is arranged between a branch Ab4 and the branch Ab1. Further is downstream of the heating register 26th an expansion valve AE4 is arranged.

The secondary strand also includes 16 a reheating branch 16.2 , the one upstream with the heating coil 26th and downstream with the external heat exchanger 18th is fluid connectable. The secondary line ends here 16 or the reheat branch 16.2 at a branch point Ab6 in the primary line 14th .

The above for the 1 Said in relation to the chiller line 28.1 with check valve R5 and / or with a rising section 28.3 is also applicable to the embodiment of the 2 applicable and it is referred to the corresponding text passages 1 referenced to avoid repetition. The same also applies to the check valve R1 or the expansion valve AE5 in the connection 22.2 .

It is generally pointed out that in the 1 and 2 several sensors are shown, which are usually designated with pTX (X = 1 .... n). The pTX sensors are used to record the pressure and / or temperature of the refrigerant. It should be noted that the number of sensors pTX (X = 1... N) or their arrangement is only shown as an example in all figures. A refrigeration system 10 according to the 1 until 2 can also have fewer or more sensors. In the examples shown, combined pressure / temperature sensors pTX are shown as sensors. However, it is just as conceivable that sensors which are separate from one another and are designed separately are used for measuring pressure or temperature and, if necessary, are also arranged spatially separated from one another along the refrigerant lines. However, each sensor pTX explicitly mentioned in the description and / or explicitly shown in the figures can be understood as a possibly relevant part of the refrigerant circuit and, if necessary, claimed, in particular about the structure of the refrigeration system 10 to be described in more detail if necessary.

It should also be noted that in the 1 and 2 several branches or nodes with AbY (Y = 1 ... n) are shown, not each of which is explicitly described. It should be noted that the number of branches AbY (Y = 1... N) or their arrangement is only shown as an example in all figures. A refrigeration system 10 according to the 1 until 2 can also have fewer or more branches. However, each branch AbY explicitly mentioned in the description and / or explicitly shown in the figures can be understood as a possibly relevant part of the topology of the refrigerant circuit and claimed if necessary, in particular about the structure of the refrigeration system 10 to be described in more detail if necessary.

The refrigeration system 10 can be operated in different modes, which are briefly described below.

In AC operation of the refrigerant circuit 11th the refrigerant, which has been compressed to high pressure, flows from the refrigerant compressor 12th with the shut-off valve open A4 in the external heat exchanger 18th . From there it flows to the high pressure section of the internal heat exchanger 20th and the fully open expansion valve AE3. Via a branch point Ab1, the refrigerant can flow to the expansion valve AE2 and into the interior evaporator 22nd flow (evaporator section 22.1 ). In parallel or alternatively, the refrigerant can enter the chiller via a branch point Ab8 and the expansion valve AE1 28 flow (chiller section 28.1 ). From the vaporizer 22nd or / and the chiller 28 the refrigerant flows into the collector on the low-pressure side 24 and through the low pressure section of the internal heat exchanger 20th back to the compressor 12th .

The heating branch is in AC operation 16.1 or the secondary line 16 by means of the shut-off valve A3 shut off so that hot refrigerant cannot pass through the heating element 26th can flow. To retrieve refrigerant from the inactive heating branch 16.1 can be designed as a shut-off valve A5 opened so that the refrigerant passes through the shut-off element A5 and the check valve R2 , with the shut-off element closed at the same time A2 , towards the collector 24 can flow.

In heating mode of the refrigerant circuit 11th becomes the shut-off valve A4 closed and the shut-off valve A3 opened so that hot refrigerant in the heating branch 16.1 can flow.

To carry out the heating function using the chiller 28 to implement a water heat pump operation, this flows by means of the refrigerant compressor 12th compressed refrigerant via the open shut-off valve A3 in the heating register 26th . On the heating register 26th heat is given off to a supply air flow directed into the vehicle interior. The refrigerant then flows through the open shut-off valve A1 and the branch point Ab1. It is fed into the chiller by means of the expansion valve AE1 28 for absorbing waste heat in a coolant circuit 28.2 arranged electrical and / or electronic components relaxed. With this heating function, the expansion valves AE3 and AE4 are closed, the shut-off valve A5 closed and the shut-off valve A2 open. You can use the shut-off valve A2 Refrigerant outsourced in water heat pump operation from a bidirectional branch 14.1 or the primary line 14th sucked off and through the check valve R2 the collector 24 are fed.

To carry out the heating function by means of the external heat exchanger 18th as a heat pump evaporator, it flows by means of the refrigerant compressor 12th compressed refrigerant via the open shut-off valve A3 for the transfer of heat to a supply air flow in the heating register 26th . Then it is over the open shut-off valve A1 into the external heat exchanger by means of the expansion valve AE3 18th relaxed to absorb heat from the ambient air. The refrigerant then flows through a heat pump return branch 15th to the collector 24 and back to the refrigerant compressor 12th . The expansion valves AE1, AE2 and AE4 remain, as does the shut-off valve A5 , closed.

An indirect delta connection can be implemented when the Shut-off valve A1 that from the refrigerant compressor 12th compressed refrigerant into the chiller by means of the expansion valve AE1 28 is relaxed, at the same time the coolant side, so in the coolant circuit 28.2 no mass flow is generated, for example the fluid used as a coolant, such as water or a water-glycol mixture, on the coolant side of the chiller 28 stops or the chiller 28 is not actively flowed through by coolant. The expansion valves AE2, AE3 and AE4 remain closed with this switching variant.

In the case of post-heating or reheat operation, the supply air flow fed into the vehicle interior is removed by means of the evaporator 22nd initially cooled and thus dehumidified. With the heat transferred to the refrigerant through evaporation and dehumidification and that of the refrigerant via the compressor 12th supplied heat can the supply air flow L by means of the heating register 26th completely or at least partially reheated.

3 shows a method in a simplified and schematic manner 500 for operating a refrigeration system 10 the 1 and 2 , wherein the method is designed in such a way that backflows of refrigerant into the chiller 28 are prevented.

In the process 500 is in a first step S501 switched to one of the (post) heating or heat pump operations described above, in particular air / heat pump operation. To do this, according to step S502 Refrigerant from the refrigerant compressor 12th to the evaporator 22nd and to the chiller branch 28.1 or. 28.3 directed. In AC operation, the primary branch valve A4 opened and the secondary branch valve A3 be closed. Alternatively, for example, the secondary branch valve can also be used in this step A3 are opened and the primary branch valve A4 be closed so that refrigerant from the refrigerant compressor 12th to the heating register 26th and downstream of the heating register 26th to the evaporator 22nd and to the chiller branch 28.1 or. 28.3 is directed.

In step S503 it is checked whether the temperature Tcool of the coolant in the coolant circuit 28.2 is lower than the temperature Tcold of the refrigerant in the chiller 28 , whereby this value is determined or estimated via the recorded low pressure. If the condition in S503 is met, step S504 repeated opening and closing of the chiller 28 assigned expansion valve AE1 carried out in such a way that downstream of the chiller 28 from the connection on the low pressure side 22.2 between evaporator 22nd and refrigeration compressors 12th refrigerant drawn in from the chiller 28 is rinsed. If the condition in S503 is not met, the operating method carried out up to that point is retained, the condition being repeatedly checked in S503.

If the condition in S503 is met, a step can alternatively or additionally be carried out S505 be performed. The expansion valve AE1 is closed or kept closed and the coolant in the chiller 28 is by means of the coolant circuit 28.1 (Waste heat from an electrical drive component) to a temperature Tcool which is greater than the temperature Tcold of the refrigerant, this value being determined or estimated via the low pressure detected by sensors, so that in the chiller 28 located refrigerant is brought to a temperature / pressure level that a return flow of refrigerant from the low-pressure side connection 22.2 between evaporator 22nd and refrigeration compressors 12th prevented.

This procedural step S505 can also be combined with the repeated opening and closing described above ( S504 ) of the expansion valve AE1; in particular, such an opening / closing or clocked actuation of the expansion valve AE1 can be carried out after the refrigerant has been warmed up in the meantime (with the expansion valve closed for a longer period of time). The combination of S505 and S504 is indicated by the dashed connecting arrow in 3 illustrated.

The procedure 500 can for both here in the 1 and 2 shown embodiments of refrigeration systems 10 be performed. With the refrigeration system 10 the 1 is then for example the evaporator 22nd included. With the refrigeration system 10 the 2 is the external heat exchanger in an air source heat pump 18th included as an evaporator, which with a corresponding interconnection ( A1 , AE3, A2 open, AE1, AE2, AE4 closed) according to the heating function already described above using the external heat exchanger 18th as a heat pump evaporator fluidically parallel to the chiller 28 is arranged. Of course it is also with the refrigeration system 10 the 2 an interconnection is possible in which the evaporator 22nd the procedure to be carried out 500 is included.

Of course, this can be done in 3 Methods shown in a simplified manner can also be interrupted or stopped due to further system conditions that are not shown in detail here. To that extent shows 3 only a small excerpt from an extensive overall operating procedure.

• - Vermeidung einer Kältemittelumverlagerung
• - Ölauslagerungung
• - Kältemittelrückholung und
• - Ölspülung

für jedes System anwendbar ist, unabhängig davon, ob es sich um eine Kälteanlage mit bzw. ohne Wärmepumpenfunktion handelt. Insbesondere wird darauf hingewiesen, dass das Verfahren auch für Systemabschnitte anwendbar ist, die ihrerseits inaktiv sind und auf einem Niederdruckniveau in ihrem passiven Zustand eingestellt sind. Daher ist der hier beispielhaft für den Chiller beschriebene Anwendungsfall bzw. das für den Chiller bereitgestellte Verfahren auch auf weitere bzw. andere Komponenten und Systemabschnitte übertragbar. Die herangezogene Systemtopologie ist eine beispielhafte Darstellung eines Anwendungsfalles, der sich besonders geeignet zur Beschreibung der Problematik sowie einer daran gekoppelten Lösungsmethodik zeigt.In summary, it is pointed out that the inventive concept carried out and described here for

• - Avoidance of refrigerant relocation
• - Oil storage
• - refrigerant recovery and
• - oil flushing

can be used for every system, regardless of whether it is a refrigeration system with or without a heat pump function. In particular, it should be pointed out that the method can also be used for system sections which are themselves inactive and are set in their passive state at a low pressure level. Therefore, the application described here as an example for the chiller or the method provided for the chiller can also be transferred to further or other components and system sections. The system topology used is an exemplary representation of an application that is particularly suitable for describing the problem and a solution methodology coupled to it.

In all cases, it is decisive for the relocation of refrigerant that the medium temperatures are lower in inactive system sections than in the active system sections. The medium flowing through or towards the inactive heat exchanger is lower than the evaporation pressure that is established or set in the active system section and the resulting or the corresponding evaporation temperature and in this way supports the inflow and condensation of refrigerant into the inactive system section. This can be restricted and prevented with the structural (valve) and procedural solutions described.

In general, the concept of the invention can thus also be described as a method for operating a refrigeration system for a motor vehicle, with an expansion element assigned to the heat exchanger being repeatedly opened and closed in a low-pressure branch that has a heat exchanger in an inactive state, so that downstream of the heat exchanger sucked in refrigerant is flushed out of the heat exchanger. As an alternative or in addition, in the method, refrigerant that is stored in the heat exchanger can be heated and evaporated, for example by another medium that acts on or flows through the heat exchanger, with the refrigerant in the heat exchanger being brought to a temperature / pressure level that is one Prevents refrigerant from flowing back. This means that instead of a highly dense liquid phase, there is a less dense gas phase.

QUOTES INCLUDED IN THE DESCRIPTION

This list of the documents listed by the applicant was generated automatically and is included solely 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 102018209769 A1 [0002]
• DE 102011118162 A1 [0003]
• DE 102012108731 A1 [0004]
• WO 2010/003484 A1 [0004]

Claims (11)

Method (500) for operating a refrigeration system (10) for a motor vehicle, the refrigeration system (10) having: a refrigerant compressor (12) which can be or is connected to a primary branch (14); at least one evaporator (18, 22) which is arranged in the primary line (14); a chiller (28) which is arranged in a chiller branch (28.1, 28.3) which is fluidically parallel to the evaporator (18, 22), the chiller (28) being assigned an expansion element (AE1) in the chiller branch (28.1) and the chiller ( 28) is connected to a coolant circuit (28.2) separate from the refrigerant circuit (11); the method comprising the steps of: Conducting refrigerant from the refrigerant compressor (12) to the evaporator (18, 22) so that refrigerant is applied to it, and up to the expansion element (AE1) of the chiller branch (28.1); if the temperature (Tcool) of the coolant is lower than the temperature of the refrigerant (Tcold) (S503): repeated opening and closing (S504) of the expansion element (AE1) assigned to the chiller (28), such that downstream of the chiller (28) from the low-pressure side connection (22.2) between the evaporator (22) and the refrigerant compressor (12), refrigerant sucked in is flushed out of the chiller (28). Method (500) for operating a refrigeration system (10) for a motor vehicle, wherein the refrigeration system (10) has: a refrigerant compressor (12) which can be or is connected to a primary branch (14); at least one evaporator (18, 22) which is arranged in the primary line (14); a chiller (28) which is arranged in a chiller branch (28.1, 28.3) which is fluidically parallel to the evaporator (22), an expansion element (AE1) being assigned to the chiller (28) in the chiller branch (28.1) and the chiller (28) is connected to a coolant circuit (28.2) separate from the refrigerant circuit (11); the method comprising the steps of: Conducting refrigerant from the refrigerant compressor (12) to the evaporator (22) so that refrigerant is applied to it, and up to the expansion element (AE1) of the chiller branch (28.1); if the temperature (Tcool) of the coolant is lower than the temperature (Tcold) of the refrigerant (S503): close or keep closed (S505) of the expansion valve (AE1) assigned to the chiller (28) and Heating the coolant in the chiller (28) by means of the coolant circuit (28.2) to a temperature (Tcool) that is greater than the temperature (Tcold) of the refrigerant, so that the refrigerant in the chiller (28) is brought to a temperature / pressure level that a backflow of refrigerant from the low-pressure side connection (22.2) between evaporator (22) and refrigerant compressor (12) is prevented. Method (500) according to Claim 1 or 2 , wherein refrigerant is conducted from the refrigerant compressor via a heat exchanger representing a heat source to the evaporator (18, 22) and to the chiller branch (28.1, 28.3). A refrigeration system (10) for a motor vehicle (10) with a refrigerant compressor (12) which can be or is connected to a primary line (14); at least one evaporator (18, 22) which is arranged in the primary line (14); a chiller (28) which is arranged in a chiller branch (28.1, 28.3) which is fluidically parallel to the evaporator (18, 22), the chiller (28) being assigned an expansion element (AE1) in the chiller branch (28.1) and the chiller ( 28) is connected to a coolant circuit (28.2) separate from the refrigerant circuit (11); characterized in that in the chiller line (28.3) downstream of the chiller (28) and upstream of a connection node (Ab2) with a low-pressure connection (22.2), which extends between the evaporator (18, 22) and the refrigerant compressor (12), a check valve ( R5) is arranged. Refrigeration system (10) Claim 4 , characterized in that a non-return valve (R1, R2) or an expansion element (AE5) on the low pressure side is arranged downstream of the evaporator (18, 22) and upstream of the connection node (Ab2). Refrigeration system (10) Claim 4 or 5 , characterized in that a section (28.4) of the chiller branch (28.3) is designed upstream of the connection node (Ab2) starting from the connection node (Ab2) and increasing relative to the low-pressure connection (22.2). Refrigeration system (10) Claim 6 , characterized in that the rising section (28.4) of the chiller branch (28.3) projects upwards at an angle of 30 ° to 90 ° relative to the imaginary plane in relation to an imaginary plane in which the low-pressure connection (22.2) runs. Refrigeration system according to one of the Claims 4 until 7th , characterized in that it has at least one heat exchanger (18, 26) representing a heat source. Refrigeration system (10) Claim 8 , characterized in that it further comprises: a secondary line (16) to which the refrigerant compressor (12) can be or is connected; a heat exchanger (26), in particular a heating register (26), which is arranged in the secondary branch; a secondary branch valve (A3) arranged between the refrigerant compressor (12) and the heat exchanger (26). Refrigeration system (10) according to one of the Claims 4 until 9 , characterized in that it is set up to carry out the method (500) according to Claim 1 or 2 perform. Motor vehicle with a refrigeration system (10) according to one of the Claims 4 until 10 .

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