DE102017213973A1 - Method for operating a refrigeration system of a vehicle having a refrigerant circuit having a cooling and heating function - Google Patents

Abstract

The invention relates to a method for operating a refrigeration system of a vehicle with a refrigerant circuit (1.1) having a cooling and heating function, in which a refrigerant compressor (2), a high-pressure heat exchanger (3) and an expansion element (AE1, AE2) of a refrigerant be flowed through, the heating function is realized by using the waste heat of the refrigerant compressor (2), a supply air flow (L1) is heated by means of the high-pressure heat exchanger, and the following process steps are carried out:
a) running up the refrigerant compressor (2) up to an initial speed,
b) determining a control difference (R _{diff, t} ) between a desired value and an actual value of a discharge temperature (T) of the supply air flow (L1),
c) determining the speed (n _KMV ) of the refrigerant compressor (2), and either
c1) closing of the expansion element (AE1, AE2), if at a maximum speed value (n _{KMV, max} ) of the refrigerant compressor (2), the low pressure (p _ND ) 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 ) of the refrigerant compressor (2) smaller than the maximum speed value (n _{KMV, max} ) and opening the expansion device (AE1, AE2) when the low pressure (P _ND ) reaches the minimum low pressure value (p _{ND, min} ), and
d) repeating the process steps b and c until no control difference (R _{diff, t} ) is measurable or the low pressure (p _ND ) has reached the minimum low pressure value (p _{ND, min} ).

Description

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

There are known refrigeration systems for vehicles with cooling and heating function, the refrigerant circuit has a designed as a refrigerant-refrigerant heat exchanger indirect condenser, which heats the supply air of the vehicle interior in the heat mode via a condenser-side coolant circuit and there integrated downstream heating heat exchanger. In addition to at least one interior evaporator, electrified vehicles require a separate coolant circuit for conditioning and temperature control of the energy accumulator, which is generally realized as a high-voltage battery. Such a coolant circuit can be coupled by means of a heat exchanger with the refrigerant circuit, wherein such a heat exchanger in turn is also designed as an evaporator for cooling an air flow 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.

Also, the use of the refrigerant circuit of a vehicle air conditioner in a heat pump operation for heating the passenger compartment is known. In its interconnection or function as a heat pump, the refrigerant circuit is able to heat an air or water flow or coolant flow and deliver this heat directly or indirectly to the air of the passenger compartment. Known heat pump systems with eg. R1234yf or R744 as refrigerant usually fall back on one to a maximum of two heat sources. Each additional integrated heat source makes the system design a little more complex or requires additional control and regulation devices to ensure proper operation.

When using the ambient air as a heat source, depending on the moisture content of the air, sooner or later icing of the heat pump evaporator may occur. In the case of a water heat pump with cooling water as the heat source, it is necessary to wait until the electrical components have produced waste heat and the coolant, ie the cooling water has absorbed this waste heat of the electrical components, in order to be able to effectively put the water heat pump into operation. With these heat sources, it is therefore often not possible, especially in a cold start phase of a vehicle, to provide sufficient or, if required, a maximum heating power alone via the "heat pump" functionality.

From the DE 10 2006 024 796 A1 a refrigeration system for a vehicle is known, which can be used in different modes for cooling, drying and heating a Zuluftstroms for the vehicle interior. In this known refrigeration system, the arranged in an air conditioner inner air heat exchanger is divided in the air flow direction, so that a first partial heat exchanger preferably for cooling the supply air, ie as a refrigerant evaporator, and the second downstream in the air direction partial heat exchanger preferably for heating the supply air, ie as a refrigerant gas cooler and possibly works as a refrigerant condenser. At maximum cooling requirement, both partial heat exchangers can be used as refrigerant evaporators for cooling and, at maximum heating requirement, both partial heat exchangers for refrigerant cooling / condensation for heating the supply air flow. In the "Heating" mode, the waste heat from the refrigerant compressor is also heated. The refrigerant compressor driven by an internal combustion engine provides sufficient compressor waste heat immediately after starting the engine at high compressor outlet temperatures of the refrigerant. In such a so-called "triangular process", the refrigerant passes through the refrigerant compressor, the inner air heat exchanger, which operates as a gas cooler, and optionally 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 to quickly heat up the vehicle interior at low vehicle ambient temperatures in a maximum heating mode of operation by operating both partial strands of the internal air heat exchanger as gas coolers.

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 also has an intermediate pressure input in addition to a low pressure input. This refrigerant compressor is followed by an indirect high-pressure heat exchanger in the function as a heating condenser, with which the compressed high-pressure refrigerant is cooled. To the intermediate pressure input of the refrigerant compressor, an intermediate pressure path is connected, which has two evaporators connected in parallel with associated expansion elements and an electric heating element connected in parallel to these evaporators. This electrical heating element serves as an additional heat source for the intermediate pressure region, whereby the proportion of gas in the mass flow of the refrigerant is increased within the intermediate pressure range, whereby the power of the compressor is to be increased. This leads from the this heating element provided additional power to an improved power 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 outdoor heat exchanger and a low-temperature heat exchanger.

Also from the DE 11 2013 005 367 T5 is a refrigeration system with a heat pump function for electric or hybrid vehicle is known, with which icing of an external heat exchanger during a heating operation is to be minimized. To this end, by means of a controller based on a current refrigerant evaporation pressure of an outer heat exchanger and a refrigerant evaporation pressure of the outer heat exchanger during non-ice formation or based on a refrigerant evaporation temperature of the outer heat exchanger and a refrigerant evaporation temperature of the outer heat exchanger during non-ice formation, ice formation on the outer Heat exchanger determined and performed the deicing by a deicing.

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

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 having a cooling and heating function having refrigerant circuit, in which

• - A flow branch with a refrigerant compressor and a downstream high-pressure downstream heat exchanger is flowed through by a refrigerant,
• - An expansion element downstream of the high pressure heat exchanger downstream,
• the heating function is realized by heating, with the waste heat of the refrigerant compressor, a supply air flow supplied into the vehicle interior of the vehicle by means of the high-pressure heat exchanger,

the following process steps are carried out:

1. a) starting and running up the refrigerant compressor, starting from a minimum speed up to an initial speed,
2. b) determining a control difference between a desired value and an actual value of a discharge temperature of the supply air flow,
3. c) determining the speed of the refrigerant compressor, and either
   • c1) closing the expansion member by a predetermined value when at a speed corresponding to the maximum speed value of the refrigerant compressor, 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 smaller than the maximum speed value and opening the expansion device by a predetermined value when the low pressure reaches the minimum low pressure value, and
4. d) Repeat the process steps b and c until the actual value of the discharge temperature has reached the desired value or 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 set point of the blow-off temperature of the supply air flow is not reached, the compressor speed, if this is less than a maximum speed value, gradually increased and then closed either the expansion element, when the maximum speed value of the compressor, the low pressure greater than the minimum low pressure value or at a compressor speed lower than the maximum speed value, the expansion member 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-off temperature has reached the setpoint or when this condition is not reached under extreme environmental conditions and therefore operated the refrigeration system 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 terminated when other heat sources for carrying out a heat pump process are available for the refrigeration system and the process in the following steps is successively switched over to the use of other heat sources.

With this method according to the invention, a heating function with maximum heating power is provided, if necessary, directly with the waste heat supplied by the refrigerant compressor, if required. The control of the Expansion means along the minimum low pressure value together with the control of the compressor speed up to the maximum speed value results in that a maximum waste heat of the refrigerant compressor for heating the vehicle cabin is provided. If necessary, possible heating power deficits can be compensated by additional auxiliary heaters possibly provided in the vehicle.

Before other heat sources for a heat pump process of the refrigeration system are available, a basic heat demand is already covered by this method. Defrosting phases in 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 completely breaking down.

According to an advantageous development of the invention, following process step b, in which the control difference between the desired value and the actual value of the blow-off temperature of the supply air flow of the vehicle interior is determined, either method step c is performed with a positive control difference or the speed of the refrigerant compressor at a negative control difference reduced a predetermined value. A positive control difference means that the actual value is smaller than the setpoint, ie. 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. the supply air flow has at least the setpoint temperature, and therefore the speed of the refrigerant compressor is reduced, thereby keeping the heating power so that the outlet temperature of the supply air flow at least constant at the setpoint level.

A further preferred embodiment of the invention provides that after an increase in the speed of the refrigerant compressor, the method steps b and c are performed when the low pressure is greater than the minimum low pressure value.

Furthermore, it is advantageous if according to a further embodiment of the invention, a stationary operation is performed 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 which is released for the system state. Accordingly, the minimum low pressure value is limited by a minimum allowable low pressure value down.

Preferably, of course, a stationary operation is performed at a non-measurable control difference following the process step b.

A further advantageous development of the invention provides that the expansion element is connected by the shortest route to the low-pressure side of the refrigerant compressor. This realizes a minimal triangle process.

An alternative triangular process is realized by downstream of the expansion means a refrigerant-refrigerant heat exchanger, wherein the refrigerant-refrigerant heat exchanger is connected downstream to the low-pressure side of the refrigerant compressor. This means that, for example, the coolant-refrigerant heat exchanger designed as a chiller is assigned the expansion element. Since refrigeration systems with heat pump function generally have such a chiller, the inventive method can be realized without constructive changes such refrigeration systems. In this case, it is preferably provided that the coolant-refrigerant heat exchanger formed as a chiller, for example, is inactive on the coolant side, ie. is operated in non-existent, so "stagnant" coolant flow.

A further advantageous embodiment of the method according to the invention provides that the high-pressure heat exchanger for the implementation of the heating function downstream of a heating coil is connected downstream. Thus, the waste heat of the refrigerant compressor is transmitted both indirectly by means of the high-pressure heat exchanger and directly via the heater to the supply air.

• 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 will now be described in detail by means of an embodiment with reference to the accompanying figures. Show it:

• 1 a flow chart as an embodiment of the method according to the invention,
• 2 a circuit diagram of a refrigeration system of a vehicle for performing the method according to 1 .
• 3 an alternative circuit diagram of a refrigeration system after 2 .
• 4 another alternative circuit diagram of a refrigeration system after 2 , and
• 5 another alternative circuit diagram of a refrigeration system after 2 ,

The with the flowchart according to 1 illustrated embodiment of the method according to the invention is by means of in 2 illustrated refrigeration system 1 carried out.

The refrigerant circuit 1.1 the refrigeration system 1 according to 2 consists of an evaporator 6 , a refrigerant compressor 2 , which together with a high-pressure heat exchanger 3 in a flow branch 1.2 of the refrigerant circuit 1.1 is arranged. This high pressure heat exchanger 3 is the refrigerant compressor 2 downstream in the flow direction S downstream of the refrigerant and designed as a high-pressure refrigerant-refrigerant heat exchanger, via a heating circuit 1.4 thermally with a designed as a coolant-air heat exchanger heater heat exchanger 3.1 is thermally coupled with water as a coolant. With a water pump 1:41 the fluid is in the heating circuit shown greatly simplified 1.4 circulated.

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

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

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

Further refrigerant cooling and condensation takes place in the refrigerant circuit 1.1 according to 2 by means of the high-pressure heat exchanger 3 downstream heating register downstream 5 ,

To the different operating modes of the refrigeration system 1 That is, to perform the heating and cooling functions, the components of the refrigerant circuit 1.1 in a certain way by means of shut-off valves A1 to A4 as well as with Absperrfunktionen trained expansion organs AE1 to AE4 connected.

To realize 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 of the refrigerant compressor 2 , whose waste heat in the form of the drive power of the refrigerant compressor 2 for heating the supply air flow supplied to the vehicle interior L1 is used. Such waste heat is produced both in electric refrigerant compressors which are used in pure electric vehicles and in mechanical compressors which are driven by a belt drive, as is the case, for example, in vehicles operated by internal combustion engines.

To carry out the triangular process, the refrigerant circuit 1.1 a line section 1.5 on, coming from one in the direction of flow S the refrigerant circuit arranged expansion element AE1 and a downstream downstream check valve R4 consists. In this triangular process, the refrigerant flows out of the flow branch 1.2 with closed shut-off valves A2 and A4 and open shut-off valve A1 in the line section 1.5 and over the check valve R4 , the refrigerant collector 8th and the low pressure portion of the internal heat exchanger 7 back to the refrigerant compressor 2 ,

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

That of the refrigerant compressor 2 High pressure compressed refrigerant is released through the expansion device AE1 relaxed to low pressure. The refrigerant absorbs the waste heat of the refrigerant compressor 2 and gives these over the high-pressure heat exchanger 3 to the coolant of the heating circuit 1.4 from, by means of the Heizungswärmeübertragers 3.1 the supply air flow L1 is heated. In the arrangement according to 3 This part of the waste heat of the Refrigerant compressor 2 also by means of the heating register 5 directly on 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 at the shut-off valve A3 is to pay attention to a bidirectional sealing function, to prevent a potential return of refrigerant to the condenser / gas cooler 9 at a pressure level difference between a first heat pump branch WPZ1 (whose function will be explained below) and the line section 1.5 come, ie in the line section 1.5 is a higher pressure level adjacent than in the first heat pump branch WPZ1 , Should this be in the flow direction of the expansion organ AE1 to shut-off valve A3 not be the case, so 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 organ AE1 integrate. Can always be excluded that the shut-off valve A3 is only monodirectionally sealing or that the pressure in the operating state triangle process in the segmented system section "condenser / gas cooler" comes to lie below that of the active process, so can waive another check valve R4 be considered.

The triangular process serves as quickly as possible maximum heat to the supply air flow as needed L1 to transmit for heating or preheating or for the maintenance conditioning of the vehicle interior, ie to provide maximum possible heating heat based on the compressor waste heat for the vehicle interior. Such a requirement occurs, for example, at low ambient temperatures and cooled vehicle interior, if no heat sources are available in the vehicle.

The implementation of such a triangulation process will become apparent from the flowchart 1 in conjunction with the 2 and 3 described. In this method, by means of a climate control unit, the compressor speed n _KMV and the low pressure p _nd depending on a control difference R _{diff, t} between a desired value and an actual value of the discharge temperature T the supply air flow L1 regulated.

This regulation is superordinate to the monitoring and adherence to limits for the maximum permissible high pressure and the maximum permissible hot gas temperature, as is also the case during operation of the system for the AC mode. These state variables are transmitted via a high-pressure-side pressure-temperature sensor pT2 downstream of the compressor 2 detected.

The actual value of the air-side outlet temperature T is determined by means of a temperature sensor, the low pressure p _nd in the refrigeration circuit 1.1 by means of a pressure-temperature sensor pT1 which according to the 2 and 3 downstream to the internal heat exchanger 7 is arranged. The setpoint of the outlet temperature T is specified by the climate control unit. As the refrigerant compressor 2 is designed as an electric refrigerant compressor, the climate control unit are also the values of the compressor speed n _KMV in front.

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

In a first process step S1 becomes the refrigerant compressor 2 starting from a minimum speed and running high up to an initial speed. The expansion organ AE1 is started with a specific value of the opening, an initial opening.

Subsequently, in a process step S2 the rule 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 outlet temperature T is less 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 outlet temperature T greater than the setpoint, ie the supply air flow L1 is too warm. 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 R _{diff, t} = 0 and thus the target outlet temperature is reached. This takes place until over process step S2 In turn, a significant deviation between setpoint and actual value can be measured.

If according to method step S4 a positive control difference R _{diff, t} > 0 is present, the method with a process 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.

With the process step S6 it is checked if the compressor speed n _KMV a maximum speed value n _{KMV, max} has reached. If this is not true, in a subsequent process step S9 the compressor speed n _KMV increased by a predetermined value (n _KMV ↑). In the other case, if the compressor speed n _KMV the maximal Compressor speed has been reached, in one step S7 checked if the low pressure p _nd a minimum low pressure value p _{ND, min} has reached. If so, the method step S3 in the stationary operation of the refrigeration system 1 passed. Otherwise, the expansion organ AE1 according to method step S8 closed by a certain value (EXV ↓), reducing the low pressure p _nd is lowered and the high pressure p _HD increases. After the process step S8 will be back to the process step S2 branched.

After increasing the compressor speed n _KMV according to method step S9 is in a subsequent process step S10 rechecked whether a negative or positive control difference R _{diff, t} is present. If no rule difference R _{diff, t} is present, ie the actual value of the outlet temperature T corresponds to the setpoint, is to the process step S7 branched back and checked whether the low pressure p _nd the minimum low pressure value p _{ND, min} equivalent. If this is the case, the branching takes place to the method step S3 , otherwise turn on process step S8 ,

Alternatively, starting from the process step S10 if there is no rule difference R _{diff, t} also directly the process step S3 carried out and thus the system continue to operate stationary, ie on the targeted start of the minimum low pressure value p _{ND, min} according to method step S7 can be omitted, since the setpoint of the outlet temperature T already set.

If according to method step S10 continue to have a positive or negative regulatory difference R _{diff, t} is present, is in a subsequent process step S11 checked if the low pressure p _nd the minimum low pressure value p _{ND, min} equivalent. If so, then according to a method step S12 the organ of expansion AE1 opened by a predetermined value (EXV ↑), reducing the low pressure p _nd above the minimum low pressure value p _{ND, min} increases, ie the pressure ratio between high and low pressure is smaller. Subsequently, from the process step S12 back to the process step S2 branched.

If according to method step S11 the low pressure p _nd the minimum low pressure value p _{ND, min} has not yet reached, is immediately on the procedural step S2 branches back.

The process steps S2 . S4 . S6 . S9 . S10 . S11 and possibly S12 are repeated until the maximum values of the compressor speed n _KMV and low pressure p _nd to adjust or the control difference R _{diff, t} Zero, ie the actual value of the discharge temperature T has reached the setpoint. In the latter case, this process step is about the process steps S2 or S10 leave.

Has with procedural step S7 the refrigerant compressor 2 the maximum speed value n _KMV is enough, but the low pressure p _nd still above the minimum low pressure value p _{ND, min} lies, becomes the organ of expansion AE1 according to method step S8 throttled, which increases the pressure ratio and thus the heating power is increased.

In accordance with this method of triangulation 1 work the expansion organ AE1 in terms of its opening and the compressor 2 in terms of its compressor speed n _KMV as control elements in such a way that the refrigerant circuit 1.1 always at the limit regarding 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 to 1 controlled triangular process, a short-term maximum heat for the vehicle interior of the vehicle is generated before other heat sources are available, with which a heat pump process can be performed.

In extreme environmental conditions, the case may occur that the setpoint of the blow-out temperature T is not achieved, so the control difference R _{diff, t} does not become zero, ie a stationary state according to method step S3 can not occur. This has the consequence that 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 mentioned operating limits, such as the maximum speed value n _{KMV, max} which represents a maximum allowable speed value and the minimum low pressure value p _{ND, min} , which is limited by a minimum allowable low pressure value down, as already indicated, the high pressure and the hot gas temperature must be monitored in the manner known to those skilled in the art and can lead to a limitation of the triangular process. For the sake of clarity, the presentation of these further operating limits is dispensed with.

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

Does the triangular process in this constellation by means of the refrigerant-coolant heat exchanger 4 implemented, the expansion organ AE1 through a shut-off valve A5 be replaced; Furthermore, depending on the system version, a waiver of the shut-off valve A4 possible. At the pipe section 1.5 can, since he only has the function for refrigerant extraction with inactive heating circuit 1.4 met, the cross section is smaller and dimensioned the node K1 (or K2) arbitrarily between the shut-off valve A1 and the check valve R1 be positioned.

This triangular process by means of the refrigerant-coolant heat exchanger 4 will according to the method 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. In connection with the implementation of the method according to 1 advantages in the case of the expansion organ AE1 also applies to the implementation of this method by means of the refrigerant-refrigerant heat exchanger 4 associated expansion organ AE2 ,

In the following, the heat pump cycle processes of the refrigeration system 1 according to the 2 and 3 described above, based on the above 1 can connect described triangular processes.

A first heat pump cycle process uses as a heat source the ambient air of the vehicle, 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 2 and 3 a first heat pump branch WPZ1 on top of the refrigerant condenser / gas cooler 9 , in the flow direction S of the refrigerant circuit 1.1 upstream of the refrigerant condenser / gas cooler 9 arranged expansion organ AE4 and upstream of this expansion organ AE4 arranged check valve R1 is formed. Between the refrigerant condenser / gas cooler 9 and the expansion organ AE4 is located, based on the AC interconnection, the high pressure section of the internal heat exchanger 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 of the refrigerant compressor 2 and this downstream high-pressure heat exchanger 3 , the first heat pump cycle process in which this first heat pump branch WPZ1 on the one hand by means of the shut-off valve A3 in the flow direction S of the refrigerant with a check valve R4 of the line section 1.5 is connected, so that in the flow direction S the refrigerant via the open shut-off valve A3 , the check valve R4 , the refrigerant collector 8th and the low pressure portion of the internal heat exchanger 7 back to the refrigerant compressor 2 can flow. On the other hand, the first heat pump branch WPZ1 upstream with the refrigerant compressor 2 and the high pressure heat exchanger 3 over the check valve R1 , the heating register 5 , the shut-off valve A4 (at 2 provided) and the shut-off valve A1 fluidly connected.

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

For this purpose, the refrigerant circuit 1.1 according to the 2 and 3 a second heat pump branch WPZ2 up, out of the expansion organ AE2 and in the flow direction S the low-pressure level downstream low-pressure refrigerant refrigerant heat exchanger downstream of the refrigerant 4 , also called chiller, exists. This second heat pump branch WPZ2 forms together with the series connection of the refrigerant compressor 2 and this downstream high-pressure heat exchanger 3 the second heat pump cycle process in which the expansion organ AE2 in the flow direction 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 3 downstream downstream. In the refrigerant circuit 1.1 according to 3 is the shut-off valve A4 not provided.

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

Furthermore, according to the 2 and 3 both the evaporator 6 as well as the refrigerant-refrigerant heat exchanger 4 one check valve each R2 and R3 Downstream downstream, allowing a flow reversal of the refrigerant through these check valves R2 and R3 back to the evaporator 6 or the refrigerant-refrigerant heat exchanger 4 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 into the refrigerant collector 8th flows.

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

To carry out the first heat pump cycle process by means of the refrigerant circuit 1.1 according to the 2 and 3 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 the open shut-off valve A3 , the check valve R4 , the refrigerant collector 8th and the low pressure portion of the internal heat exchanger 7 back to the refrigerant compressor 2 can flow. To 2 In this first heat pump circuit process, the shut-off valve also becomes A4 open. Further, in this first heat pump cycle process, the expansion device executed with a shut-off function AE2 and AE3 blocked.

For carrying out the second heat pump cycle process by means of 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 3 over the heating register 5 , the check valve R1 by means of the expansion organ AE2 in the refrigerant-refrigerant heat exchanger 4 is relaxed, while the evaporator 6 associated expansion organ AE3 and the organ of expansion AE4 of the first heat pump branch WPZ1 be locked, which are each equipped with a shut-off function. To 2 In this second heat pump cycle also the shut-off valve A 4 is opened.

Also with the in the 4 and 5 illustrated refrigeration systems 1 can the above related to the 2 and 3 described triangular processes and the heat pump processes are performed. The difference is that the in the 2 and 3 from the shut-off valves A1 and A 2 existing valve arrangement for branching the refrigerant from the high pressure heat exchanger 3 either in the direction of the condenser / gas cooler 9 or in the direction of the heating register 5 according to the 4 and 5 already directly with the high-pressure outlet of the refrigerant compressor 2 is arranged. This is the high-pressure heat exchanger 3 only flows through during the triangular processes and the heat pump process of refrigerant. In AC operation, the shut-off valve A1 closed, allowing the refrigerant directly from the refrigerant compressor 2 over 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 2 to 5 can also be omitted.

If mechanical compressors are used which operate on the basis of mass flow regulation, the speed signal of an electric compressor can be substituted by a current signal which is proportional to the mass flow and thus instead of the speed signal according to FIG 1 be taken over.

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

LIST OF REFERENCE NUMBERS

1

refrigeration plant

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

Line section of the refrigerant circuit 1.1

2

Refrigerant compressor

3

High-pressure heat exchanger

3.1

Heating heat exchanger

4

Refrigerant-refrigerant heat exchanger

4.1

Coolant circuit of the refrigerant-refrigerant heat exchanger 4th

5

heater

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 element

AE2

expansion element

AE3

expansion element

AE4

expansion element

K1

junction

K2

junction

L1

supply air flow

n _KMV

Speed of the refrigerant compressor 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 side pressure temperature sensor

pT2

High-pressure side pressure-temperature sensor

R _{diff, t}

Control difference between a setpoint and an actual value of an outlet temperature T

S

Flow direction of the refrigerant

R1

check valve

R2

check valve

R3

check valve

R4

check valve

T

Outlet temperature of the supply air flow L1

WPZ1

first heat pump branch

WPZ2

second heat pump branch

...

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been 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.

Cited patent literature

• DE 102006024796 A1 [0005, 0006]
• DE 102013214267 A1 [0007]
• DE 112013005367 T5 [0008]

Claims (9)

A method for operating a refrigeration system (1) of a vehicle having a cooling and heating function having refrigerant circuit (1.1), in which - a flow branch (1.2) with a refrigerant compressor (2) and a downstream high-pressure heat exchanger (3) of a refrigerant is flowed through, - an expansion element (AE1, AE2) downstream of the high-pressure heat exchanger (3), - the heating function is realized by using the waste heat of the refrigerant compressor (2) in the vehicle interior of the vehicle supplied supply air (L1) by means of 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 of a Outlet temperature (T) of the supply air flow (L1), c) determining the speed ( n _KMV ) of the refrigerant compressor (2), and either c1) Closing of the expansion device (AE1, AE2) by a predetermined value, if at a maximum speed value (n _{KMV, max} ) corresponding speed (n _KMV ) of the refrigerant compressor (2) of 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 ) of the refrigerant compressor (2) smaller than the maximum speed value (n _{KMV, max} ) and opening of 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) repeating the process steps b and c until the actual value of the discharge temperature (T) has reached the desired value or 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} ). Method 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 given a negative control difference (R _{diff, t} ) , Method according to Claim 1 or 2 in which, after an increase in the rotational speed (n _KMV ) of the refrigerant compressor (2), process steps b and c are performed when 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 a stationary operation is performed 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 a non-measurable control difference (R _{diff, t} ) after the method step b, a stationary operation is performed. Method according to one of the preceding claims, in which the expansion element (AE1) is connected by the shortest route to the low-pressure side of the refrigerant compressor (2). Method according to one of Claims 1 to 5 in which the expansion member (AE2) downstream of a refrigerant-refrigerant heat exchanger (4), wherein the refrigerant-refrigerant heat exchanger (4) is connected to the downstream side with the low pressure side of the refrigerant compressor (2). Method 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, wherein the high-pressure heat exchanger (3) for carrying out the heating function downstream of a heating coil (5) is connected downstream.

Images