DE102017213973B4 - Method for operating a refrigeration system of a vehicle with a refrigerant circuit having a cooling and heating function - Google Patents

Abstract

Method for operating a refrigeration system (1) of a vehicle with a refrigerant circuit (1.1) having a cooling and heating function, in which a flow branch (1.2) with a refrigerant compressor (2) and a downstream high-pressure heat exchanger (3) from a refrigerant is flowed through, - an expansion device (AE1, AE2) is connected downstream of the high-pressure heat exchanger (3), - the heating function is realized by using the waste heat from the refrigerant compressor (2) to supply air to the vehicle interior of the vehicle (L1) using the High-pressure heat exchanger is heated, and the following process steps are carried out: a) Starting and starting up the refrigerant compressor (2), starting from a minimum speed up to an initial speed, b) determining a control difference (R) between a setpoint and an actual value of a blow-out temperature (T ) the supply air flow (L1), c) determining the speed (n) of the refrigerant compressor (2), and either c1) closing the expansion device (AE1, AE2) by a predetermined value if, at a speed (n) of the refrigerant compressor (2) corresponding to the maximum speed value (n), the low pressure (p) on the low pressure side of the refrigerant circuit (1.1) is greater than is a minimum low pressure value (p), or c2) increase the speed (n) of the refrigerant compressor (2) at a speed (n) of the refrigerant compressor (2) less than the maximum speed value (n) and open the expansion device (AE1, AE2) by a predetermined value when the low pressure (p) reaches the minimum low pressure value (p), andd) repeating process steps b and c until the actual value of the blow-out temperature (T) has reached the desired value or the low pressure (p) on the low pressure side of the refrigerant circuit ( 1.1) has reached the minimum low pressure value (p).

Description

The invention relates to a method for operating a refrigeration system of a vehicle with a refrigerant circuit with a cooling and heating function.

Refrigeration systems for vehicles with a cooling and heating function are known, the refrigerant circuit of which has an indirect condenser designed as a refrigerant-coolant heat exchanger, which heats the supply air of the vehicle interior via a condenser-side coolant circuit and the heating heat exchanger integrated downstream there. In addition to at least one interior evaporator, electrified vehicles require a separate coolant circuit for conditioning and temperature control of the energy store, which is generally implemented as a high-voltage battery. Such a coolant circuit can be 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 water. Alternatively, the cooling of an energy store or other high-voltage components can also take place via direct evaporation of refrigerant in the component.

The use of the refrigerant circuit of a vehicle air conditioning system in a heat pump operation to heat up the passenger compartment is also known. In its connection or function as a heat pump, the refrigerant circuit is able to heat an air or water flow or coolant flow and emit this heat directly or indirectly to the air in the passenger cell. Known heat pump systems with, for example, R1234yf or R744 as a refrigerant generally use one to a maximum of two heat sources. Each additionally integrated heat source makes the system design somewhat more complex or requires additional control and regulating elements in order to achieve correct operation.

If the ambient air is used as a heat source, depending on the moisture content of the air, the heat pump evaporator may freeze sooner or later. In the case of a water heat pump with cooling water as the heat source, if the coolant has not been preconditioned, you must wait until the electrical components have generated waste heat and the coolant, i.e. the cooling water, has absorbed this waste heat from the electrical components in order to be able to effectively start the water heat pump. With these heat sources, it is often not possible, especially in a cold start phase of a vehicle, to provide sufficient or, if necessary, a maximum heating output using the "heat pump" functionality alone.

From the DE 10 2006 024 796 A1 a refrigeration system for a vehicle is known which can be used in different operating modes for cooling, drying and heating a supply air flow for the vehicle interior. In this known refrigeration system, the inner air heat exchanger arranged in an air conditioning unit is divided in the air flow direction, so that a first partial heat exchanger preferably works for cooling the supply air, i.e. as a refrigerant evaporator, and the second partial heat exchanger connected downstream in the air direction preferably for heating the supply air, i.e. as a refrigerant gas cooler and possibly works as a refrigerant condenser. With maximum cooling requirements, both partial heat exchangers can be used as refrigerant evaporators for cooling, and with maximum heating requirements, both partial heat exchangers can be used for cooling / condensing the refrigerant to heat the supply air flow. In the "Heating" operating mode, the waste heat from the refrigerant compressor is also used for heating. The refrigerant compressor driven by an internal combustion engine delivers sufficient compressor waste heat at high compressor outlet temperatures of the refrigerant immediately after starting the engine. In such a so-called “triangular process”, the refrigerant passes through the refrigerant compressor, the internal air heat exchanger, which works as a gas cooler, and, if necessary, an expansion device that can be arranged either before or after the gas cooler.

This known refrigeration system according to the DE 10 2006 024 796 A1 is typically operated for rapid heating of the vehicle interior at low vehicle ambient temperatures in an operating mode “maximum heating”, in that both sub-strands of the internal air heat exchanger work as a gas cooler.

The DE 10 2013 214 267 A1 describes a refrigeration system with a heat pump function for electric or hybrid vehicles. The refrigerant circuit of this known refrigeration system has a refrigerant compressor 6 which, in addition to a low pressure inlet, also has an intermediate pressure inlet. This refrigerant compressor is followed by an indirect high-pressure heat exchanger in the function of a heating condenser, with which the refrigerant compressed to high pressure is cooled. An intermediate pressure path is connected to the intermediate pressure inlet of the refrigerant compressor, which has two evaporators connected in parallel with associated expansion elements and an electrical heating element connected in parallel with these evaporators. This electrical heating element serves as an additional heat source for the intermediate pressure range, as a result of which the gas fraction in the mass flow of the refrigerant is increased within the intermediate pressure range, as a result of which the performance of the compressor is to be increased. So that leads from this Heating element provided additional performance to an improved performance contribution of the refrigerant compressor, especially at low ambient temperatures. The low-pressure inlet of the refrigerant compressor is connected to a low-pressure path, which consists of a low-pressure heat exchanger as an external heat exchanger and a low-temperature heat exchanger.

Also from the DE 11 2013 005 367 T5 a refrigeration system with a heat pump function for electric or hybrid vehicles is known, with which icing of an external heat exchanger is to be minimized during heating operation. For this purpose, by means of a control device based on a current refrigerant evaporation pressure of an external heat exchanger and a refrigerant evaporation pressure of the external heat exchanger during non-ice formation or on the basis of a refrigerant evaporation temperature of the external heat exchanger and a refrigerant evaporation temperature of the external heat exchanger during non-ice formation, ice formation on this external one Heat exchanger determined and de-icing carried out by a de-icing device.

From the DE 11 2013 004 046 T5 A method for operating a refrigeration system of an electric vehicle with a refrigerant circuit with a cooling and heating function is known, with which the temperature of the traction battery of the electric vehicle is to be kept within a desired temperature range. This refrigeration system comprises a refrigerant circuit which is thermally coupled on the one hand via a high-pressure refrigerant-coolant heat exchanger to a high-temperature coolant circuit and on the other hand by means of a chiller to a battery coolant circuit having an electrical heater. The high-temperature coolant circuit is thermally coupled to an electric drive machine of the electric vehicle and a heater core for conditioning a supply air flow supplied to the passenger compartment. The temperature of the battery is controlled by means of a control device, the heat generated during the charging process of the battery and the waste heat of the battery being stored in the battery coolant circuit for use in the air conditioning of the passenger compartment and at the same time the temperature of the battery being controlled in this way, that it is within the desired temperature range.

It is an object of the invention to provide a method for operating a refrigeration system of a vehicle with a refrigerant circuit having a cooling and heating function and, if necessary, to use it to provide heating energy with the maximum possible output.

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

• - ein Strömungszweig mit einem Kältemittelverdichter und einem stromabwärts nachgeschalteten Hochdruck-Wärmeübertrager von einem Kältemittel durchströmt wird,
• - ein Expansionsorgan dem Hochdruck-Wärmeübertrager stromabwärts nachgeschaltet wird,
• - die Heizfunktion realisiert wird, indem mit der Abwärme des Kältemittelverdichters ein in den Fahrzeuginnenraum des Fahrzeugs zugeführter Zuluftstrom mittels des Hochdruck-Wärmeübertragers beheizt wird,

werden folgende Verfahrensschritte durchgeführt:

1. a) Starten und Hochlaufen des Kältemittelverdichters, ausgehend von einer Minimaldrehzahl bis zu einer Anfangsdrehzahl,
2. b) Bestimmen einer Regeldifferenz zwischen einem Sollwert und einem Istwert einer Ausblastemperatur des Zuluftstroms,
3. c) Bestimmen der Drehzahl des Kältemittelverdichters, und entweder
   • c1) Schließen des Expansionsorgans um einen vorgegebenen Wert, wenn bei einer dem maximalen Drehzahlwert entsprechenden Drehzahl des Kältemittelverdichters der Niederdruck auf der Niederdruckseite des Kältemittelkreislaufs größer als ein minimaler Niederdruckwert ist, oder
   • c2) Erhöhen der Drehzahl des Kältemittelverdichters bei einer Drehzahl des Kältemittelverdichters kleiner als der maximale Drehzahlwert und Öffnen des Expansionsorgans um einen vorgegebenen Wert, wenn der Niederdruck den minimalen Niederdruckwert erreicht, und
4. d) Wiederholen der Verfahrensschritte b und c bis der Istwert der Ausblastemperatur den Sollwert erreicht hat oder der Niederdruck auf der Niederdruckseite des Kältemittelkreislaufs den minimalen Niederdruckwert erreicht hat.

In this method for operating a refrigeration system of a vehicle with a refrigerant circuit having a cooling and heating function, in which

• a refrigerant flows through a flow branch with a refrigerant compressor and a downstream high-pressure heat exchanger,
• an expansion element is connected downstream of the high-pressure heat exchanger,
• the heating function is realized in that the waste heat from the refrigerant compressor is used to heat a supply air flow fed into the vehicle interior by means of the high-pressure heat exchanger,

the following process steps are carried out:

1. a) starting and starting up the refrigerant compressor, starting from a minimum speed up to an initial speed,
2. b) determining a control difference between a target value and an actual value of a blow-out temperature of the supply air flow,
3. c) determining the speed of the refrigerant compressor, and either
   • c1) closing the expansion element by a predetermined value if, at a speed of the refrigerant compressor corresponding to the maximum speed value, the low pressure on the low pressure side of the refrigerant circuit is greater than a minimum low pressure value, or
   • c2) increasing the speed of the refrigerant compressor at a speed of the refrigerant compressor less than the maximum speed value and opening the expansion element by a predetermined value when the low pressure reaches the minimum low pressure value, and
4. d) repeating process steps b and c until the actual value of the blow-out temperature has reached the desired value or until the low pressure on the low-pressure side of the refrigerant circuit has reached the minimum low-pressure value.

In this method, as long as the setpoint of the discharge temperature of the supply air flow has not been reached, the compressor speed, if this is less than a maximum speed value, is gradually increased and then either the expansion element is closed if the maximum pressure value of the compressor means that the low pressure is greater than the minimum low pressure value or is below the maximum speed value Compressor speed the expansion element is opened by a predetermined value when the low pressure has reached the minimum low pressure value. These process steps are repeated until the actual value of the blow-out temperature has reached the setpoint or if this condition is not reached under extreme environmental conditions and the refrigeration system is therefore operated along the limits determined by the maximum speed value of the compressor and the minimum low pressure value of the low pressure. This latter state is ended when other heat sources for carrying out a heat pump process are available for the refrigeration system and the process is successively switched to the use of other heat sources in the subsequent steps.

With this method according to the invention, a heating function with maximum heating power is provided directly with the waste heat supplied by the refrigerant compressor, if required. The control of the expansion element along the minimum low pressure value together with the control of the compressor speed up to its maximum speed value means that a maximum waste heat of the refrigerant compressor is provided for heating the vehicle cabin. Possible heating output deficits can be compensated for if necessary using additional heaters that may be provided in the vehicle.

Before other heat sources are available for a heat pump process in the refrigeration system, a basic heat requirement is already covered by this method. Defrosting phases on a gas cooler used as an evaporator for an air heat pump process can be bridged by means of the method according to the invention without the heating power collapsing completely.

According to an advantageous development of the invention, following step b, in which the control difference between the setpoint and the actual value of the outlet temperature of the supply air flow of the vehicle interior is determined, either step c is carried out with a positive control difference or the speed of the refrigerant compressor with a negative control difference reduced a predetermined value. A positive control difference means that the actual value is smaller than the setpoint, i. H. the supply air flow into the vehicle interior is still too cold. A negative control difference means that the actual value has reached or exceeded the setpoint, i.e. the supply air flow has at least the target temperature, and therefore the speed of the refrigerant compressor is reduced in order thereby to keep the heating power and thus also the outlet temperature of the supply air flow at least constant at the target value level.

A further preferred embodiment of the invention provides that after increasing the speed of the refrigerant compressor, method steps b and c are carried out if the low pressure is greater than the minimum low pressure value.

Furthermore, it is advantageous if, according to a further embodiment of the invention, stationary operation is carried out when the speed of the refrigerant compressor corresponds to the maximum speed value and the low pressure has reached the minimum low pressure value. This maximum speed value corresponds to a permissible value that is released for the system status. Accordingly, the minimum low pressure value is also limited by a minimum permissible low pressure value.

In the case of a non-measurable control difference, of course, stationary operation is preferably carried out after method step b.

Another advantageous development of the invention provides that the expansion element is connected to the low-pressure side of the refrigerant compressor by the shortest route. A minimal triangular process is thus realized.

An alternative triangular process is realized in that a coolant-refrigerant heat exchanger is connected downstream of the expansion element, the coolant-refrigerant heat exchanger being connected downstream to the low-pressure side of the refrigerant compressor. This means that, for example, the expansion element is assigned to the coolant-refrigerant heat exchanger designed as a chiller. Since refrigeration systems with a heat pump function generally have such a chiller, the method according to the invention can be implemented without constructive changes to such refrigeration systems. It is preferably provided here that the coolant-refrigerant heat exchanger, for example designed as a chiller, is inactive on the coolant side, i.e. is operated with a non-existent, ie "standing" coolant flow.

A further advantageous embodiment of the method according to the invention provides that a heating register is connected downstream on the downstream side of the high-pressure heat exchanger in order to carry out the heating function. This means that the waste heat from the refrigerant compressor is transferred to the supply air flow both indirectly using the high-pressure heat exchanger and directly via the heating register.

• 1 ein Ablaufdiagramm als Ausführungsbeispiel des erfindungsgemäßen Verfahrens,
• 2 ein Schaltbild einer Kälteanlage eines Fahrzeugs zur Durchführung des Verfahrens nach 1,
• 3 ein alternatives Schaltbild einer Kälteanlage nach 2,
• 4 ein weiteres alternatives Schaltbild einer Kälteanlage nach 2, und
• 5 ein weiteres alternatives Schaltbild einer Kälteanlage nach 2.

The invention is described in detail below using an exemplary embodiment with reference to the accompanying figures. Show it:

• 1 2 shows a flowchart as an exemplary embodiment of the method according to the invention,
• 2nd a circuit diagram of a refrigeration system of a vehicle for performing the method according to 1 ,
• 3rd an alternative circuit diagram of a refrigeration system 2nd ,
• 4th another alternative circuit diagram of a refrigeration system 2nd , and
• 5 another alternative circuit diagram of a refrigeration system 2nd .

That with the flow chart according to 1 The exemplary embodiment of the method according to the invention is illustrated by means of the 2nd refrigeration system shown 1 carried out.

The refrigerant circuit 1.1 the refrigeration system 1 according to 2nd consists of an evaporator 6 and a refrigerant compressor 2nd , which together with a high pressure heat exchanger 3rd in a flow branch 1.2 of the refrigerant circuit 1.1 is arranged. This high pressure heat exchanger 3rd is the refrigerant compressor 2nd downstream in the flow direction S downstream of the refrigerant and designed as a high-pressure refrigerant-coolant heat exchanger, via a heating circuit 1.4 thermally with a heating heat exchanger designed as a coolant-air heat exchanger 3.1 is thermally coupled with water as a coolant. With a water pump 1.41 the fluid in the heating circuit is shown in a highly simplified form 1.4 circulated.

This also includes the refrigerant circuit 1.1 next to the evaporator 6 , the refrigerant compressor 2nd as well as the high pressure heat exchanger 3rd a refrigerant condenser / gas cooler 9 , a heating register 5 as another refrigerant condenser / gas cooler, one the evaporator 6 upstream expansion organ AE3 , an internal heat exchanger 7 with a high pressure and low pressure section and a refrigerant collector 8th , where carbon dioxide (R744) is used as the refrigerant.

The evaporator 6 , the heating heat exchanger 3.1 and the heating register 5 are according to 2nd in an air conditioner 1.3 the refrigeration system 1 housed.

In a heating or heat pump operation of the refrigerant circuit 1.1 by means of the high pressure heat exchanger working at high pressure level 3rd the refrigerant is cooled and condensed and the heat thus transferred to the water as a coolant is transferred to the heating heat exchanger 3.1 supplied with which a supply air flow supplied to the vehicle interior L1 is heated directly.

A further refrigerant cooling and condensation takes place in the refrigerant circuit 1.1 according to 2nd by means of the high pressure heat exchanger 3rd downstream heating register 5 .

The different operating modes of the refrigeration system 1 , namely performing the heating and cooling functions, become the components of the refrigerant circuit 1.1 in a certain way by means of shut-off valves A1 to A4 as well as expansion units designed with shut-off functions AE1 to AE4 connected.

To implement the heating function of the refrigerant circuit 1.1 On the one hand, a so-called "triangular process" and, on the other hand, heat pump cycle processes are carried out on the basis of different heat sources.

The triangular process uses only the waste heat from the refrigerant compressor 2nd , its waste heat in the form of the drive power of the refrigerant compressor 2nd for heating the supply air flow supplied to the vehicle interior L1 is used. Such waste heat arises both in the case of electric refrigerant compressors which are used in purely electric vehicles and in the case of mechanical compressors which are driven by a belt drive, as is the case, for example, in vehicles operated by internal combustion engines.

The refrigerant circuit has to carry out the triangular process 1.1 a line section 1.5 on that from a in the flow direction S of the refrigerant circuit arranged expansion device AE1 and a check valve downstream of this R4 consists. In this triangular process, the refrigerant flows out of the flow branch 1.2 with shut-off valves closed A2 and A4 and open shut-off valve A1 in the line section 1.5 and via the check valve R4 , the Refrigerant collector 8th and the low pressure section of the inner heat exchanger 7 back to the refrigerant compressor 2nd .

According to 2nd is the line section 1.5 with one of the two shut-off valves A1 and A4 connecting node K1 connected. Alternatively, it is also possible to use this line section 1.5 only downstream after the heating register 5 with the refrigerant circuit 1.1 to connect like this by means of a node K2 according to 3rd is shown. According to this triangular process 3rd the refrigerant flows out of the flow branch 1.2 with the shut-off valve closed A2 and open shut-off valve A1 via the heating register 5 in the line section 1.5 and then via the refrigerant collector 8th and the low pressure section of the inner heat exchanger 7 back to the refrigerant compressor 2nd . Here are the shut-off valves equipped with a shut-off function AE2 , AE3 and AE4 blocked.

Except for the lack of the shut-off valve A4 points the refrigerant circuit 1.1 according to 3rd one with the refrigerant circuit 1.1 according to 2nd matching structure.

That from the refrigerant compressor 2nd refrigerant compressed to high pressure is released by the expansion device AE1 relaxed to low pressure. The refrigerant takes the waste heat from the refrigerant compressor 2nd and passes this on to the high-pressure heat exchanger 3rd to the coolant of the heating circuit 1.4 with which by means of the heating heat exchanger 3.1 the supply air flow L1 is heated. When arranging after 3rd becomes part of the waste heat of the refrigerant compressor in this triangular process 2nd also by means of the heating register 5 directly to the supply air flow L1 transferred while another part indirectly via the heating heat exchanger 3.1 on the supply air flow L1 is transmitted.

Especially with the shut-off valve A3 a bidirectional sealing function must be ensured in order to prevent potential refrigerant backflow into the condenser / gas cooler 9 with a pressure level difference between a first heat pump branch WPZ1 (whose function is explained below) and the line section 1.5 shut off, ie in the line section 1.5 there is a higher pressure level than in the first heat pump branch WPZ1 . Should this be in the direction of flow from the expansion device AE1 to shut-off valve A3 would not be the case, would be in front of the shut-off valve A3 to provide an additional check valve and the check valve R4 directly downstream of the expansion device AE1 to involve. Can always be excluded that the shut-off valve A3 is only mono-directional sealing or that the pressure in the triangular process operating state in the segmented system section "condenser / gas cooler" is below that of the active process, this means that a further check valve can be dispensed with R4 be considered.

The triangular process is used to get maximum heat to the supply air flow as quickly as possible L1 for heating or preheating or for maintaining air conditioning in the vehicle interior, ie to provide the maximum possible heat based on the compressor waste heat for the vehicle interior. Such a need arises, for example, at low ambient temperatures and when the vehicle interior has cooled down, when no heat sources are yet available in the vehicle.

The execution of such a triangular process is shown in the flow chart 1 in connection with the 2nd and 3rd described. In this method, the compressor speed is determined using an air conditioning control unit n _KMV and the low pressure p _ND depending on a control difference R _{diff, t} between a setpoint and an actual value of the blow-out temperature T of the supply air flow L1 regulated.

The control and compliance with limits for the maximum permissible high pressure and the maximum permissible hot gas temperature is superior to this regulation, as is also the case during operation of the system for AC mode. These state variables are monitored by a pressure-temperature sensor on the high-pressure side pT2 downstream of the compressor 2nd detected.

The actual value of the air discharge temperature T the low pressure is determined by means of a temperature sensor p _ND in the refrigeration cycle 1.1 using a pressure-temperature sensor pT1 that according to the 2nd and 3rd downstream after the internal heat exchanger 7 is arranged. The setpoint of the blow-out temperature T is specified by the climate control device. Since the refrigerant compressor 2 is designed as an electric refrigerant compressor, the climate control unit also has the values of the compressor speed n _KMV in front.

In the case of mechanical compressors, the compressor speed is usually determined from the engine speed and gear ratio between the output and drive shafts.

In a first step S1 becomes the refrigerant compressor 2nd started from a minimum speed and runs up to an initial speed. The expansion organ AE1 is started with a certain value of the opening, an initial opening.

Then in one process step S2 the control difference R _{diff, t} determined. A positive or negative rule difference R _{diff, t} leads to the next process step S4 , otherwise to a procedural step S3 with which the refrigeration system 1 is controlled in a stationary operation. A positive control difference R _{diff, t} > 0 means that the actual value of the blow-out temperature T is smaller than the setpoint, ie the supply air flow L1 is still too cold. A negative control difference R _{diff, t} <0 means that the actual value of the blow-out temperature T is greater than the setpoint, ie the supply air flow L1 is too warm. A stationary operation is characterized by the fact that the system can continue to be operated with the current setting and control or operating parameters, since the control difference is R _{diff, t} = 0 and the target blow-out temperature has thus been reached. That is as long as up through process step S2 again a significant deviation between the target and actual value can be measured.

If according to process step S4 a positive control difference R _{diff, t} > 0 is the method with one step S6 otherwise, in one process step S5 the compressor speed n _KMV reduced ( n _KMV ↓) and then with process step S3 in a stationary operation of the refrigeration system 1 passed over.

With the procedural step S6 it is checked whether the compressor speed n _KMV a maximum speed value n _{KMV, max} has reached. If this is not the case, then in a subsequent process step S9 the compressor speed n _KMV increased by a specified value (n _KMV ↑). Otherwise, if the compressor speed n _KMV has reached the maximum compressor speed in one process step S7 checked whether the low pressure p _ND a minimum low pressure value p _{ND, min} has reached. If this is the case, proceed according to process step S3 in the stationary operation of the refrigeration system 1 passed over. Otherwise, the expansion organ AE1 according to process step S8 closed by a certain value (EXV ↓), causing the low pressure p _ND is lowered and the high pressure p _HD increases. After the procedural step S8 will go back to the procedural step S2 branches.

After increasing the compressor speed n _KMV according to process step S9 is in a subsequent process step S10 checked again whether a negative or positive control difference R _{diff, t} is present. If there is no control difference R _{diff, t} is present, ie the actual value of the blow-out temperature T corresponds to the setpoint, is on the process step S7 branched back and checked whether the low pressure p _ND the minimum low pressure value p _{ND, min} corresponds. If this is the case, the process step is branched to S3 , otherwise again on process step S8 .

Alternatively, starting from the process step S10 if there is no control difference R _{diff, t} also directly the process step S3 carried out and thus the system can continue to be operated immediately in a stationary manner, ie on the targeted approach to the minimum low pressure value p _{ND, min} according to process step S7 can be dispensed with as the setpoint of the blow-out temperature T is already set.

If according to process step S10 still a positive or negative system deviation R _{diff, t} is present in a subsequent process step S11 checked whether the low pressure p _ND the minimum low pressure value p _{ND, min} corresponds. If this is the case, a step is taken S12 the expansion organ AE1 opened by a predetermined value (EXVT), whereby the low pressure p _ND about the minimum low pressure value p _{ND, min} increases, ie the pressure ratio between high and low pressure becomes smaller. Then the process step S12 back to the process step S2 branches.

If according to process step S11 the low pressure p _ND the minimum low pressure value p _{ND, min} has not yet reached the process step immediately S2 branched back.

The procedural steps S2 , S4 , S6 , S9 , S10 , S11 and possibly S12 are repeated until the maximum values of the compressor speed are reached n _KMV and low pressure p _ND adjust or the control difference R _{diff, t} Becomes zero, ie the actual value of the blow-out temperature T has reached the setpoint. In the latter case, this sequence of process steps is carried out via the process steps S2 or S10 leave.

Has with procedural step S7 the refrigerant compressor 2nd the maximum speed value n _KMV reached, but the low pressure p _ND still above the minimum low pressure value p _{ND, min} is the expansion organ AE1 according to process step S8 throttled, which increases the pressure ratio and thus increases the heating output.

With this procedure according to the triangular process 1 act the expansion organ AE1 regarding its opening and the compressor 2nd in terms of its compressor speed n _KMV together as control elements in such a way that the refrigerant circuit 1.1 always at the limit with regard to the maximum speed value n _{KMV, max} and the minimum low pressure value p _{ND, min} is operated and thereby a maximum waste heat for heating the vehicle interior by means of the supply air flow L1 provided.

With this according 1 regulated triangular process, a maximum of heating heat is generated for the vehicle interior of the vehicle before other heat sources are available with which a heat pump process can be carried out.

In extreme ambient conditions, the setpoint of the blow-out temperature can occur T is not reached, i.e. the control difference R _{diff, t} does not become zero, ie a steady state according to the method step S3 cannot occur. As a result, the refrigerant circuit 1.1 along the operating limits, namely the maximum speed value n _{KMV, max} and the minimum low pressure value p _{ND, min} is operated until in the presence of a heat source available for a heat pump process, the operation of the Refrigerant circuit 1.1 can be switched to a more efficient heating measure.

In addition to these operating limits, such as the maximum speed value n _{KMV, max} , which represents a maximum permissible speed value and the minimum low pressure value p _{ND, min} , which is limited by a minimum permissible low pressure value, the high pressure and the hot gas temperature must, as already indicated, be monitored in the manner known to the person skilled in the art and can lead to a limitation of the triangular process. For the sake of clarity, these additional operating limits are not shown.

Another implementation of the triangular process is instead of that in the line section 1.5 arranged expansion organ AE1 the refrigerant-coolant heat exchanger designed as a chiller 4th assigned expansion organ AE2 to use. For this purpose, the water flow through the chiller is stopped, ie the coolant remains "standing" in this coolant-coolant heat exchanger 4th , so that no heat transfer can take place at this heat exchanger. In this mode of operation of the triangular process, the refrigerant becomes the flow branch 1.2 via the open shut-off valves A1 and A4 (with shut-off valve closed A2 and closed expansion organ AE1 ), the heating register 5 and the check valve R1 by means of the expansion organ AE2 in the refrigerant-coolant heat exchanger 4th relaxes and then flows through the check valve R2 , the refrigerant collector 8th and the low pressure section of the inner heat exchanger 7 back to the refrigerant compressor 2nd . This with the refrigerant-coolant heat exchanger 4th carried out triangular process is for the refrigerant circuit 1.1 of both 2nd and 3rd identical.

The triangular process in this constellation is achieved using the refrigerant-coolant heat exchanger 4th implemented, the expansion organ AE1 through a shut-off valve A5 be replaced; depending on the system version, there is also a waiver of the shut-off valve A4 possible. At the line section 1.5 can, since it only has the function of refrigerant extraction when the heating circuit is inactive 1.4 fulfilled, the cross-section dimensioned smaller and the node K1 (respectively. K2 ) anywhere between the shut-off valve A1 and the check valve R1 be positioned.

This triangular process using the refrigerant-coolant heat exchanger 4th is carried out according to the procedure described above 1 by means of the associated expansion organ AE2 instead of the expansion organ AE1 of the line section 1.5 carried out. The related to the implementation of the procedure 1 advantages mentioned in the case of the expansion device AE1 also apply when this method is carried out using the refrigerant-coolant heat exchanger 4th assigned expansion organ AE2 .

Below are the heat pump cycle processes of the refrigeration system 1 according to the 2nd and 3rd are described, which refer to the above with reference to 1 described triangular processes can connect.

A first heat pump cycle process uses the ambient air of the vehicle as the heat source, the heat of which is used to heat the air supplied to the vehicle interior.

For this purpose, the refrigerant circuit 1.1 according to the 2nd and 3rd a first heat pump branch WPZ1 on that of the refrigerant condenser / gas cooler 9 , in the direction of flow S of the refrigerant circuit 1.1 upstream of the refrigerant condenser / gas cooler 9 arranged expansion organ AE4 and the upstream in front of this expansion organ AE4 arranged check valve R1 is formed. Between the refrigerant condenser / gas cooler 9 and the expansion organ AE4 is the high-pressure section of the internal heat exchanger in relation to the AC connection 7 . However, this section is subjected to low pressure in the air heat pump process.

This first heat pump branch WPZ1 forms together with the flow branch 1.2 , consisting of the series connection from the refrigerant compressor 2nd and the downstream high pressure heat exchanger 3rd , the first heat pump cycle in which this first heat pump branch WPZ1 on the one hand by means of the shut-off valve A3 in the direction of flow S of the refrigerant with a check valve R4 of the line section 1.5 is connected so that in the direction of flow S the refrigerant through the open shut-off valve A3 , the check valve R4 , the refrigerant collector 8th and the low pressure section of the inner heat exchanger 7 back to the refrigerant compressor 2nd can flow. On the other hand is the first heat pump branch WPZ1 upstream with the refrigerant compressor 2nd and the high pressure heat exchanger 3rd via the check valve R1 , the heating register 5 , the shut-off valve A4 (at 2nd provided) and the shut-off valve A1 fluid-connected.

A second heat pump cycle uses the waste heat of electrical components such as high-voltage batteries, electric motors or power electronics as the heat source.

For this purpose, the refrigerant circuit 1.1 according to the 2nd and 3rd a second heat pump branch WPZ2 on that from the expansion organ AE2 and that in the direction of flow S of the refrigerant downstream low-pressure refrigerant-coolant heat exchanger 4th , also called chiller, exists. This second heat pump branch WPZ2 forms together with the series connection from the refrigerant compressor 2nd and the downstream high-pressure heat exchanger 3rd the second heat pump cycle, in which the expansion element AE2 in the direction of flow S by means of the shut-off valve A1 , the shut-off valve A4 , the heating register 5 and the check valve R1 the high pressure heat exchanger 3rd is connected downstream. With the refrigerant circuit 1.1 according to 3rd is the shut-off valve A4 not provided.

This refrigerant-coolant heat exchanger designed as a chiller 4th forms a coolant circuit together with a heat source, not shown 4.1 and is used by the heat source on the coolant of the coolant circuit 4.1 Heat transferred via the refrigerant in the refrigerant circuit 1.1 record, in this function the refrigerant-coolant heat exchanger 4th together with the expansion organ AE2 works as an evaporator. This heat is used on the one hand by means of the high-pressure heat exchanger 3rd the air supplied to the vehicle interior indirectly and by means of the heating register 5 heated directly.

Furthermore, according to the 2nd and 3rd both the vaporizer 6 as well as the refrigerant-coolant heat exchanger 4th one check valve each R2 and R3 downstream downstream, so that a flow reversal of the refrigerant through these check valves R2 and R3 back into the evaporator 6 or the refrigerant-coolant heat exchanger 4th can be excluded. The check valves R2 and R3 as well as the check valve R4 form together with the refrigerant collector 8th a node through which the refrigerant from the check valves R2 , R3 and R4 in the refrigerant collector 8th flows.

According to the 2nd and 3rd can the high pressure heat exchanger 3rd with the shut-off valve open A2 and blocked shut-off valve A1 with the refrigerant condenser / gas cooler 9 be fluid-connected, the direct connection of the high pressure heat exchanger 3rd with the condenser / gas cooler 9 only in an AC mode of the refrigeration system 1 in which the two shut-off valves A1 and A3 are locked.

To carry out the first heat pump cycle using the refrigerant circuit 1.1 according to the 2nd and 3rd becomes the shut-off valve A2 closed and the shut-off valve A1 opened, causing the refrigerant through the heating coil 5 and the check valve R1 by means of the expansion organ AE4 in the first heat pump branch WPZ1 is relaxed to low pressure and via the open shut-off valve A3 , the check valve R4 , the refrigerant collector 8th and the low pressure section of the inner heat exchanger 7 back to the refrigerant compressor 2nd can flow. To 2nd the shutoff valve is also used in this first heat pump cycle A4 open. In addition, in this first heat pump cycle process, the expansion elements designed with a shut-off function are used AE2 and AE3 blocked.

To carry out the second heat pump cycle using the second heat pump branch WPZ2 becomes the shut-off valve A2 closed and the shut-off valve A1 opened, causing the refrigerant from the high pressure heat exchanger 3rd via the heating register 5 and the check valve R1 by means of the expansion organ AE2 in the refrigerant-coolant heat exchanger 4th is relaxed, the evaporator at the same time 6 assigned expansion organ AE3 and the expansion organ AE4 of the first heat pump branch WPZ1 be blocked, each equipped with a shut-off function. To 2nd shutoff valve A 4 is also opened in this second heat pump cycle.

Even with those in the 4th and 5 shown refrigeration systems 1 can those related to the above 2nd and 3rd described triangular processes and the heat pump processes. The difference is that in the 2nd and 3rd from the shut-off valves A1 and A 2 existing valve arrangement for branching the refrigerant from the high pressure heat exchanger 3rd either towards the condenser / gas cooler 9 or in the direction of the heating register 5 according to the 4th and 5 already directly with the high pressure outlet of the refrigerant compressor 2nd is arranged. This turns the high-pressure heat exchanger 3rd only flows through refrigerant during the triangular processes and the heat pump process. The shut-off valve is in AC mode A1 closed so that the refrigerant directly from the refrigerant compressor 2nd via the open shut-off valve A2 in the condenser / gas cooler 9 can flow.

A heating register 5 in the refrigeration systems 1 according to the 2nd to 5 can also be omitted.

If mechanical compressors are used which operate on the basis of mass flow control, the speed signal of an electrical compressor can be substituted with a current signal proportional to the mass flow and thus instead of the speed signal 1 be taken over.

In addition, it is also possible to operate mechanical compressors via their own external electrical drives, which in turn can be controlled via a speed signal, while communication with the mechanical compressor via a current signal, which is ideally proportional to a mass flow.

Reference symbol list

1

Refrigeration system

1.1

Refrigerant circuit of the refrigeration system 1

1.2

Flow branch of the refrigerant circuit 1.1

1.3

Air conditioning unit of the refrigeration system 1

1.4

Heating circuit

1.41

water pump

1.5

Section of the refrigerant circuit 1.1 .

2nd

Refrigerant compressors

3rd

High pressure heat exchanger

3.1

Heating heat exchanger

4th

Refrigerant-coolant heat exchanger

4.1

Coolant circuit of the refrigerant-coolant heat exchanger 4th

5

Heating register

6

Evaporator

7

internal heat exchanger

8th

Refrigerant collector

9

Gas cooler

A1

Shut-off valve

A2

Shut-off valve

A3

Shut-off valve

A4

Shut-off valve

AE1

Expansion organ

AE2

Expansion organ

AE3

Expansion organ

AE4

Expansion organ

K1

Node

K2

Node

L1

Supply air flow

n _KMV

Refrigerant compressor speed 2

n _{KMV, max}

maximum speed value of the refrigerant compressor 2

p _ND

Low pressure value

p _{ND, min}

minimal low pressure value

pT1

Low-pressure pressure / temperature sensor

pT2

High-pressure pressure / temperature sensor

R _{diff, t}

Control difference between a setpoint and an actual value of a blow-out temperature T

S

Flow direction of the refrigerant

R1

check valve

R2

check valve

R3

check valve

R4

check valve

T

Blow-out temperature of the supply air flow L1

WPZ1

first heat pump branch

WPZ2

second heat pump branch

Claims (9)

Method for operating a refrigeration system (1) of a vehicle with a refrigerant circuit (1.1) having a cooling and heating function, in which - a flow branch (1.2) with a refrigerant compressor (2) and a downstream high-pressure heat exchanger (3) from a refrigerant is flowed through, - an expansion device (AE1, AE2) is connected downstream of the high-pressure heat exchanger (3), - the heating function is realized by using the waste heat from the refrigerant compressor (2) to supply air to the vehicle interior of the vehicle (L1) using the High-pressure heat exchanger is heated, and the following process steps are carried out: a) Starting and running up the refrigerant compressor (2), starting from a minimum speed up to an initial speed, b) determining a control difference (R _{diff, t} ) between a setpoint and an actual value Blow-out temperature (T) of the supply air flow (L1), c) determining the Speed (n _KMV) of the refrigerant compressor (2), and either c1) closing the expansion device (AE1, AE2) by a predetermined value if at a maximum speed value (n _{KMV, max)} corresponding rotational speed (n _KMV) of the refrigerant compressor (2 ) the low pressure (p _ND ) on the low pressure side of the refrigerant circuit (1.1) is greater than a minimum low pressure value (p _{ND, min} ), or c2) increasing the speed (n _KMV ) of the refrigerant compressor (2) at a speed (n _KMV ) the refrigerant compressor (2) less than the maximum speed value (n _{KMV, max} ) and opening the expansion device (AE1, AE2) by a predetermined value when the low pressure (p _ND ) reaches the minimum low pressure value (p _{ND, min} ), and d ) Repeat process steps b and c until the actual value of the blow-out temperature (T) has reached the setpoint or until the low pressure (p _ND ) on the low-pressure side of the refrigerant circuit (1.1) has reached the minimum low-pressure value (p _{ND, min} ). Procedure according to Claim 1 , in which, following method step b, either method step c is carried out with a positive control difference (R _{diff, t} ) or the speed (n _KMV ) of the refrigerant compressor (2) is reduced by a predetermined value with a negative control difference (R _{diff, t} ) . Procedure according to Claim 1 or 2nd , in which after an increase in the speed (n _KMV ) of the refrigerant compressor (2), process steps b and c are carried out if the low pressure (p _ND ) is greater than the minimum low pressure value (p _{ND, min} ). Method according to one of the preceding claims, in which stationary operation is carried out when the speed (n _KMV ) of the refrigerant compressor (2) corresponds to the maximum speed value (n _{KMV, max} ) and the low pressure (p _ND ) the minimum low pressure value (p _{ND , min} ) has reached. Method according to one of the preceding claims, in which stationary operation is carried out after method step b if the control difference (R _{diff, t} ) is not measurable. Method according to one of the preceding claims, in which the expansion element (AE1) is connected in the shortest possible way to the low-pressure side of the refrigerant compressor (2). Procedure according to one of the Claims 1 to 5 , in which the expansion element (AE2) is connected downstream of a coolant-coolant heat exchanger (4), the coolant-coolant heat exchanger (4) being connected on the downstream side to the low-pressure side of the coolant compressor (2). Procedure according to Claim 7 , in which the coolant-refrigerant heat exchanger (4) is operated inactive on the coolant side. Method according to one of the preceding claims, in which a heating register (5) is connected downstream of the high-pressure heat exchanger (3) for performing the heating function.

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