DE102020133636A1 - Motor vehicle with refrigeration system and control device for recalibrating pressure/temperature sensors and method for operating a refrigeration system - Google Patents

Abstract

A motor vehicle (100), in particular an at least partially electrically powered motor vehicle, is described, having a refrigeration system (10), the refrigeration system (10) having a refrigerant compressor (12), at least one heat exchanger (18, 22, 26, 28, 40) and at least has a sensor arrangement (pT2, pT4), the sensor arrangement (pT2, pT4) having at least one pressure sensor and at least one temperature sensor or at least one combined pressure/temperature sensor (pT2, pT4), and the sensor arrangement (pT) in an area (24.1 ) the refrigeration system (10) is arranged, in which the refrigerant is present in two phases or just one phase lying on the boiling line or dew line; a control device (50) which is set up to control the operation of the refrigeration system (10). It is provided that the control device (50) is set up to, during the service life of the motor vehicle (100), the at least one sensor arrangement (pT2, pT4) during operation of the motor vehicle (100) or during operation of the refrigeration system (10), in particular regularly to check and to correct pressure values (pef) and/or temperature values (Tef) recorded by the sensor arrangement (pT2) as a function of specific material values (SW) of the refrigerant, such that a corrected temperature value (Tkorr ) or/and a corrected pressure value (pkorr) are available. A method for operating a refrigeration system (10) is also described.

Description

The invention relates to a motor vehicle, in particular an at least partially electrically driven motor vehicle, with a refrigeration system, the refrigeration system having a refrigerant compressor, at least one heat exchanger and at least one sensor arrangement, the sensor arrangement having at least one pressure sensor and at least one temperature sensor or at least one combined pressure/temperature sensor and wherein the sensor arrangement is arranged in a region of the refrigeration system in which the refrigerant is present in two phases or just in one phase lying on the boiling or dew line; and with a control device that is set up to control or regulate the operation of the refrigeration system.

From the DE 10 2007 010 647 A1 a method for calibrating a refrigeration system is known, with a measurement error of the temperature sensor being determined and compensated for on the basis of measurements from an evaporation pressure sensor system.

the JP 2005 106 380 A shows a refrigeration circuit in which measurement errors of the pressure sensor are determined based on measurements of the temperature sensor.

the WO 2020 148 270 A1 shows a calibration method for a refrigerant circuit, a composition of the refrigerant being determined by means of test runs via temperature and pressure measurements.

Sensor devices in cooling circuits of motor vehicles are subject to increased measurement deviations for cost reasons and are installed in the motor vehicle after an initial calibration by the sensor manufacturer. A later recalibration cannot be planned. This results in the problem that, in the two-phase operating state of refrigerant, overheating or subcooling is erroneously measured or recorded due to combined measurement deviations of the pressure and temperature sensors, which on the one hand do not exist in two-phase operating states and on the other hand (in this case not considered in more detail) single-phase operating states are determined too high or too low. As a result, the control or regulation of the refrigeration system installed in the motor vehicle tries to remove the actually correctly working system from the area of overheating or undercooling, although such is not the case and is only based on measurement errors. Accordingly, the refrigeration system cannot be operated optimally.

The object on which the invention is based is seen in specifying a (partly) electrically driven motor vehicle with a refrigeration system, optionally expandable to include a heat pump function, in which the refrigeration system can be operated optimally based on measurement results from the sensor devices.

This object is achieved by a motor vehicle having the features of patent claim 1 or patent claim 12. Advantageous configurations with expedient developments are specified in the dependent patent claims.

A motor vehicle is therefore proposed, in particular a motor vehicle that is at least partially electrically driven, with a refrigeration system, the refrigeration system having a refrigerant compressor, at least one heat exchanger and at least one sensor arrangement, the sensor arrangement having at least one pressure sensor and at least one temperature sensor or at least one combined pressure/temperature sensor and wherein the sensor arrangement is arranged in a region of the refrigeration system in which the refrigerant is present in two phases or just in one phase lying on the boiling or dew line; and with a control device that is set up to control the operation of the refrigeration system. It is provided that the control device is set up to check the at least one sensor arrangement during the service life of the motor vehicle, in particular regularly during operation of the motor vehicle or during operation of the refrigeration system, and to calculate pressure values and/or temperature values recorded by the sensor arrangement as a function of specific To correct material values of the refrigerant used, such that a corrected temperature value and / or a corrected pressure value are available for the control of the refrigeration system.

Such a configuration makes it possible to improve or optimize the control or regulation of the refrigeration system operation independently of an original accuracy of installed sensor devices or in the case of changes in the accuracy over the running time. Accordingly, the control stability and the control accuracy, in particular in the case of states of the refrigerant in the two-phase range, can be increased.

In the motor vehicle, the refrigeration system can have a low-pressure-side coolant accumulator, with the sensor arrangement being arranged downstream of the coolant accumulator and upstream of the coolant compressor. With such a structure, it is ensured that the sensor arrangement is in an area or line section in which the refrigerant is usually present in two phases, so that reliable recalibration is possible tion of the sensor arrangement is possible.
Alternatively, it is also conceivable to place the sensor upstream of the collector on the low-pressure side and thus downstream of a heat exchanger working as an evaporator.

In the motor vehicle, the refrigeration system can have a first heat exchanger, which is used as a condenser or gas cooler, and a second heat exchanger, which is used for further cooling or supercooling of the refrigerant, with a refrigerant collector being arranged between the first and the second heat exchanger, and with the sensor arrangement is arranged downstream of the refrigerant collector and upstream of the second heat exchanger. Such a structure also enables the sensor arrangement to be located in an area or line section in which the refrigerant usually comes to rest on the boiling point in liquid form or possibly also in two phases, so that reliable recalibration of the sensor arrangement is possible.

In the motor vehicle, the control device can be set up to determine or estimate an expected temperature value based on a pressure value detected by the sensor arrangement and as a function of the specific material properties of the refrigerant.

The control device can also be set up to compare the temperature value to be expected with the temperature value detected by the sensor arrangement and to calculate or estimate a temperature value deviation.

Furthermore, the control device can be set up to store the temperature value deviation and to calculate or estimate a corrected temperature value for each recorded temperature value.

In other words, the pressure of the refrigerant can be measured and the associated saturation temperature (expected temperature value) can then be determined. If there is a deviation between the measured temperature and the saturation temperature, the recorded temperature can be corrected. The correction of the measured temperature value can be made dependent in particular on whether the temperature value deviation is within or outside a predetermined tolerance band or tolerance range. For example, the tolerance range can be +/- 0.2 to 0.4 K based on a saturation temperature for the measured pressure.

In the motor vehicle, the control device can be set up to determine or estimate an expected pressure value based on a temperature value detected by the sensor arrangement and as a function of the specific material properties of the refrigerant.

The control device can be set up to compare the expected pressure value with the pressure value detected by the sensor arrangement and to calculate or estimate a pressure value deviation.

Furthermore, the control device can be set up to store the pressure value deviation and to calculate or estimate a corrected pressure value for each recorded pressure value.

In other words, the temperature of the refrigerant can be measured and the associated saturation pressure (expected pressure value) can then be determined. If there is a discrepancy between the measured pressure and the saturation pressure, the recorded pressure value can be corrected. The correction of the measured pressure value can be made dependent in particular on whether the pressure value deviation is within or outside a predetermined tolerance band or tolerance range. For example, starting from a saturation pressure for the measured temperature, the tolerance range can be +/-0.1 to 0.2 bar.

In the motor vehicle, the control device can be set up to determine, as a function of a plurality of determined temperature value deviations and pressure value deviations, whether the associated pressure sensor or the associated temperature sensor detects fewer values to be corrected. As a result, it can be determined or ascertained which of the relevant sensors is working more reliably or more precisely.

In this case, the control device can also be set up to use the detected value of one sensor, which requires less correction, as the basis for correcting the detected value of the other sensor. This ensures that a recalibration of one sensor is not based on heavily falsified or poor measurement results from the other sensor. Thus, by taking into account the respective sensor accuracy or reliability determined during operation or during the running time of the motor vehicle, which can change over a long period of time, the recalibration can be adapted and optimized on a case-by-case basis.

If sensors with different measuring ranges are installed in a vehicle refrigeration system, where at least two of them are similar in terms of their technical design, the sensors that are similar or similar can ideally be recalibrated and adjusted with one another.

According to an alternative, a motor vehicle, in particular an at least partially electrically driven motor vehicle, is proposed with a refrigeration system, the refrigeration system having a refrigerant compressor, at least one heat exchanger and at least one sensor arrangement, the sensor arrangement having at least one pressure sensor and at least one temperature sensor or at least one combined pressure /Has temperature sensor and wherein the sensor arrangement is arranged in a region of the refrigeration system in which the refrigerant is present in two phases; and with a control device that is set up to control the operation of the refrigeration system. It is provided that the control device is set up to check the at least one sensor arrangement during the service life of the motor vehicle, in particular regularly when the motor vehicle is stationary, and to correct pressure values recorded by the sensor arrangement as a function of a measured ambient temperature and of specific material values of the refrigerant, such that a corrected pressure value is available for the control of the refrigeration system.

This makes it possible to carry out a recalibration of the sensor arrangement or of the individual sensors when the motor vehicle is stationary for a longer period of time. In particular, it can be taken into account that the entire refrigeration system, and thus also the refrigerant, has assumed the ambient temperature after a longer period of standstill. This means that a (rest) pressure value (saturation pressure) is set in the refrigeration system that directly reflects the ambient temperature. Thus, with such a configuration, the pressure sensor can be calibrated based on a measured ambient temperature.

Such a measure can be used in particular in refrigeration systems, optionally equipped with a heat pump function, which are idle for a longer period of time and thermally homogenized, i.e. completely conditioned, so that the ambient temperature is present at every point in the system. In this way, a reliable sensor calibration for the entire system or a comparison of the sensors with one another can take place based on the measured pressures and transferred to the temperatures or vice versa.

For this purpose, the motor vehicle can also have a further temperature sensor that detects the ambient temperature. This temperature sensor is independent of a temperature sensor for the refrigerant. The detected ambient temperature can be provided at the control unit. If at least two temperature sensors are installed, when calibrating the sensors in the idle state, it must be ensured that their recorded temperatures are at a comparable level, ultimately also as a criterion for whether thorough conditioning to the ambient temperature level has taken place completely and reliably. If the difference between the respective sensors is too high, recalibration should be avoided or you should wait a little longer to see whether the measured temperature values are even closer.

If a refrigeration system, especially one with a heat pump function, has dead volumes, in particular depending on the respective mode of operation, it must be ensured before a (re)calibration when the vehicle is stationary that its segmentation is canceled so that all system sections of the Refrigeration system with each other in (fluid) connection to each other. In this way, a possibly incorrect balancing of the system variables, in particular due to different refrigerant distributions in the respective sections, can be avoided.

A method is also proposed for operating a refrigeration system in a motor vehicle, in particular in an at least partially electrically driven motor vehicle, the refrigeration system having a refrigerant compressor, at least one heat exchanger and at least one sensor arrangement, the sensor arrangement having at least one pressure sensor and at least one temperature sensor or at least one has a combined pressure/temperature sensor and wherein the sensor arrangement is arranged in a region of the refrigeration system in which the refrigerant is present in two phases or just in one phase lying on the boiling or dew line. It is provided that in the method during the service life of the motor vehicle, the at least one sensor arrangement is checked, in particular regularly, during operation of the motor vehicle or during operation of the refrigeration system, and pressure values and/or temperature values recorded by the sensor arrangement are measured as a function of specific material values of the material used Refrigerant are corrected such that a corrected temperature value and / or a corrected pressure value are provided for the control of the refrigeration system.

Optional further steps to the method can in particular from those already mentioned above described features of the motor vehicle or the control device can be removed.

According to an alternative, a method for operating a refrigeration system in a motor vehicle, in particular in an at least partially electrically powered motor vehicle, is proposed, the refrigeration system having a refrigerant compressor, at least one heat exchanger and at least one sensor arrangement, the sensor arrangement having at least one pressure sensor and at least one temperature sensor or has at least one combined pressure/temperature sensor and wherein the sensor arrangement is arranged in a region of the refrigeration system in which the refrigerant is present in two phases or just in one phase lying on the boiling or dew line. It is provided that in the method during the service life of the motor vehicle, the at least one sensor arrangement is checked regularly, in particular when the motor vehicle is stationary, and pressure values recorded by the sensor arrangement are corrected as a function of a measured ambient temperature and of specific material values of the refrigerant used, such that a corrected pressure value is provided for the control of the refrigeration system.

Optional further steps for the method can be inferred in particular from the features of the motor vehicle or the control device already described above.

Different refrigerants can be used in a refrigeration system described above or in a method described for operating a refrigeration system.

Purely as an example, it is pointed out that R744, for example, is used as a supercritical refrigerant. A refrigeration system is usually filled with a guide value of 260g R744 per liter volume, which is currently applicable but can be adjusted at any time. In this case, filling is based in particular on the definition made for the specific mass or density to be met or the maximum permissible specific mass or density for certain system boundary conditions in relation to a permissible (rest) pressure for an associated thermal load. Correspondingly, the density characteristic is known in particular for the supercritical state, so that from this, especially in the idle state, an expected temperature value can be inferred from a measured pressure value or an expected pressure value can be inferred from a measured temperature value. In summary, this means for such a refrigerant that for the subcritical state of rest the relationships between pressure and temperature on the boiling and dew point curve or within the two-phase area can be used and for the supercritical state reference can be made to the sealing characteristic. Of course, this is not only possible for the refrigerant R744 mentioned as an example, but also for other refrigerants used in the motor vehicle sector. As already described above, this also applies in particular to the stationary state of a vehicle or system that has been conditioned to ambient conditions.

• 1 ein schematisches und vereinfachtes Schaltbild einer Kälteanlage für ein Kraftfahrzeug;
• 2 ein Diagramm eines Verfahrens zum Betreiben einer Kälteanlage;
• 3 ein schematisches und vereinfachtes Schaltbild einer Kälteanlage für ein Kraftfahrzeug;

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

• 1 a schematic and simplified circuit diagram of a refrigeration system for a motor vehicle;
• 2 a diagram of a method for operating a refrigeration system;
• 3 a schematic and simplified circuit diagram of a refrigeration system for a motor vehicle;

In 1 1 shows an embodiment of a refrigeration system 10 for a motor vehicle 100, shown in simplified form as a rectangle, in a schematic and simplified manner. The refrigeration system 10 includes a refrigerant circuit 11, which can be operated both in a refrigeration system operation (also called AC operation for short) and in a heat pump mode. In the embodiment shown, the refrigeration system 10 comprises a refrigerant compressor 12, an external heat exchanger 18, an internal heat exchanger 20, an evaporator 22 and an accumulator or refrigerant collector 24. The external heat exchanger 18 can be designed as a condenser or gas cooler. In particular, the external heat exchanger 18 can be flowed through in both directions in the illustrated embodiment.

The evaporator 22 is shown here by way of example as a front evaporator for a vehicle. The evaporator 22 is also representative of other evaporators possible in a vehicle, such as rear evaporators, which can be arranged parallel to one another in terms of flow. In other words, the refrigeration system 10 includes at least one evaporator 22.

A shut-off valve A4 is arranged downstream of the compressor 12 . An expansion valve AE2 is provided upstream of the evaporator 22 .

Within the scope of this description, in the entire refrigerant circuit 11 of the refrigeration system 10, the section from the compressor 12 to the outer heat exchanger 18, to the inner heat exchanger 20 and to the evaporator 22 as the primary line 14 .

The refrigeration system 10 further includes a heating register 26 (also referred to as a heating condenser or heating gas cooler). A shut-off valve A3 is arranged upstream of the heating register 26 . A shut-off valve A1 is arranged downstream of the heating register 26 . Furthermore, an expansion valve AE4 is arranged downstream of the heating register 26 .

Within the scope of this description, the section from the compressor 12 to the heating register 26, to the expansion valve AE4 and to a branch Ab2 is referred to as the secondary branch 16 in the entire refrigerant circuit of the refrigeration system 10 . The secondary branch 16 includes a heating branch 16.1, which extends from the shut-off valve A3 via the heating register 26 to the shut-off valve A1. Secondary line 16 also includes an after-heating branch or reheat branch 16.2, which can be fluidly connected to heating register 26 upstream and to external heat exchanger 18 downstream. The secondary line 16 or the reheat branch 16.2 opens into the primary line 14 at a branching point Ab2.

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

The refrigeration system 10 can also have an electrical heating element 30 which is designed, for example, as a high-voltage PTC heating element. The electric heating element 30 is used as an additional heater for a supply air flow L guided into the vehicle interior. The electric heating element 30 can be accommodated in an air conditioning unit 32 together with the heating register 26 and the evaporator 22 . In this case, the electrical heating element 30 can be arranged downstream of the heating register 26 .

In the 1 check valves R1 and R2 are also visible. Furthermore, some high-pressure-side sensors pT1, pT5, pT6 for detecting the pressure and/or temperature of the refrigerant are also shown. It is pointed out that the number of high-pressure-side sensors and their arrangement is only shown here as an example. In the example shown, combined pressure/temperature sensors pT1, pT5 and pT6 are shown as sensors. However, it is just as conceivable that sensors that are separate from one another are used for measuring pressure or temperature and, if necessary, are also arranged spatially separately from one another along the refrigerant lines.

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

In AC operation of the refrigerant circuit 11, the refrigerant compressed to high pressure flows from the refrigerant compressor 12 when the shut-off valve A4 is open into the outer heat exchanger 18. From there it flows to the high-pressure section of the inner heat exchanger 20 and the fully open expansion valve AE3. The refrigerant can flow to the expansion valve AE2 and into the interior evaporator 22 via a branch point Ab1 (evaporator section 22.1). In parallel or alternatively, the refrigerant can flow into the chiller 28 (chiller section 28.1) via a branch point Ab4 and the expansion valve AE1. The refrigerant flows from the evaporator 22 and/or the chiller 28 on the low-pressure side into the collector 24 and through the low-pressure section of the internal heat exchanger 20 back to the compressor 12.

In AC operation, the heating branch 16.1 or the secondary line 16 is shut off by means of the shut-off valve A3, so that hot refrigerant cannot flow through the heating register 26. To retrieve refrigerant from the inactive heating branch 16.1, the shut-off element A5, which is designed as a shut-off valve, can be opened so that the refrigerant can flow in the direction of the collector 24 via the shut-off element A5 and the non-return valve R2, with the shut-off element A2 being closed at the same time.

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

In order to carry out the heating function by means of the chiller 28 in order to implement water heat pump operation, the refrigerant compressed by means of the refrigerant compressor 12 flows into the heating register 26 via the open shut-off valve A3. At the heating register 26, heat is given off to a supply air flow L guided into the vehicle interior. The refrigerant then flows via the open shut-off valve A1 and the branch point Ab1. It is expanded by means of the expansion valve AE1 in the chiller 28 to absorb waste heat from the electrical and/or electronic components arranged in a coolant circuit 28.2. In this heating function, the expansion valves AE3 and AE4 are closed, the shut-off valve A5 is closed and the shut-off valve A2 open. In this case, via the shut-off valve A2 during water heat pump operation, refrigerant that has been removed can be sucked out of a bidirectional branch 14.1 or the primary line 14 and fed to the collector 24 via the check valve R2.

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

An indirect delta connection can be implemented in that when the shut-off valve A1 is open, the refrigerant compressed by the refrigerant compressor 12 is expanded by means of the expansion valve AE1 into the chiller 28, with no mass flow being generated at the same time on the coolant side, i.e. in the coolant circuit 28.2, i.e. the as Coolant fluid used, such as water or water-glycol mixture, remains on the coolant side of the chiller 28 or the chiller 28 is not actively flowed through by coolant. The expansion valves AE2, AE3 and AE4 remain closed with this switching variant.

In an after-heating or reheat operation, the supply air flow L fed into the vehicle interior is first cooled by means of the evaporator 22 and thus dehumidified. With the heat transferred to the refrigerant by evaporation and dehumidification and the heat supplied to the refrigerant via the compressor 12, the supply air flow L can be completely or at least partially reheated by means of the heating register 26.

For this purpose, the refrigeration system 10 , in particular the air conditioning unit 32 , has adjustable, in particular controllable and pivotable, temperature flaps 34 between the evaporator 22 and the heating register 26 . In the illustrated example, left and right temperature doors 34L and 34R (in 1 shown schematically) arranged. The temperature doors 34L, 34R can be adjusted or pivoted between an open position, referred to as the 100% position, and a closed position, referred to as the 0% position. Alternatively, it is also possible to connect the temperature flaps 34R, 34L downstream of the heating register 26.

In the 100% position, the entire supply air flow L flowing through the evaporator 22 is guided via the heating register 26 and heated before it can flow into the passenger compartment of the vehicle. In the 0% position, the entire supply air flow L flowing through the evaporator 22 flows in the bypass around the heating register 26 without heating and thus without absorbing heat into the passenger compartment.

In an x position of the temperature flaps 34L and 34R with 0%<x<100%, these temperature flaps are only partially open, so that only a partial air flow of the supply air flow L flowing through the evaporator 22 is routed via the heating register 26. This heated partial air flow can then be mixed with the remaining, cooled and dehumidified partial air flow. The intake air flow L heated in this way is supplied to the passenger compartment of the vehicle. By way of example, a 50% position indicates that the temperature flaps 34R and 34L are only half open, ie 50%.

A sensor device pT2 is arranged on the low-pressure side of the refrigeration system 10, in particular downstream of the evaporator 22 and downstream of the chiller 28. In the example of 1 the sensor device pT2 is arranged downstream of the refrigerant collector 24 . In particular, the sensor device pT2 is provided between the coolant collector 24 and the internal heat exchanger 20 .

In this area of the refrigeration system 10 or in a line section 24.1 between the refrigerant collector 24 and the refrigerant compressor 12 or upstream of an optionally available internal heat exchanger 20, the refrigerant is usually in two phases, i.e. both gaseous and liquid.

In the refrigeration system 10 described here by way of example, a control device 50 that is communicatively connected to the actuators and sensors of a refrigeration system 10 can be set up to, during the service life of motor vehicle 100, monitor the sensor arrangement or sensor device pT2 during operation of motor vehicle 100 or during operation of the To check refrigeration system 10 in particular regularly. In the example shown, the sensor device pT2 is a combined pressure/temperature sensor with which the pressure and the temperature of the refrigerant can be recorded.

The control device 50 is also set up to process pressure values and/or temperature values detected by the sensor arrangement pT2 as a function of specific material values of the cooling medium to be corrected by means such that a corrected temperature value and/or a corrected pressure value are available for the control of the refrigeration system 10 . Said material values and their tables or relationships between the pressure and temperature of a refrigerant used in each case are stored in the control device 50 .

It is pointed out that the control device 50 can also be part of a higher-level control device of the motor vehicle 100 .

The mode of operation of the control device 50 is explained below using a simplified diagram or process sequence 500 of FIG 2 described. Such a function of the control device 50 or such a method can be referred to as recalibration, for example. Furthermore, such a function or such a method can be carried out at specific points in time. For example, it is conceivable for the calibration of the sensor arrangement to be repeated regularly at intervals of several weeks in order to be able to ensure optimized operation of the refrigeration system 10 over the entire service life of the motor vehicle.

The control device 50 is set up in particular to determine an expected temperature value Tew based on a pressure value pef detected, for example, by the sensor arrangement pT2 or the corresponding pressure sensor and as a function of the specific material values SW of the refrigerant. For this purpose, for example, the pressure value pef is recorded in step S501. Furthermore, according to a step S502, a temperature value Tef is recorded.

According to step S503, the temperature value Tew to be expected is determined based on the detected pressure pef and as a function of the specific material values SW. The expected temperature value Tew can be determined, for example, based on the pressure and temperature relationships on the boiling/dew line or within the two-phase region or based on a density characteristic for the refrigerant based on the recorded pressure value pef.

The control device 50 can also be set up to compare the temperature value Tew to be expected with the temperature value Tef detected by the sensor arrangement and to calculate a temperature value deviation Tdiff. According to step S504 it can therefore be determined how large the difference or the deviation Tdiff is between the recorded temperature Tef and the temperature Tew to be expected.

The control device 50 can also be set up to store the temperature value deviation Tdiff and to calculate a corrected temperature value Tkorr for each recorded temperature value Tef.

According to a step S505, it can be checked whether the temperature deviation Tdiff is within a tolerance range or a tolerance band, which can be defined by a lower limit value Tug and an upper limit value Tog. For the temperature deviation Tdiff, Tug can be -0.2 to -0.4K, for example, and Tog can be +0.2 to +0.4K.

If the temperature deviation Tdiff is within the limit values Tug and Tog, it is determined according to step S506 that the corrected temperature Tkorr corresponds to the detected temperature Tef. In this case, the recorded temperature value Tef is not corrected.

If the temperature deviation Tdiff is outside the limit value Tug or Tog, the corrected temperature value Tkorr is calculated according to step S507, the recorded temperature Tef being corrected by the temperature deviation Tdiff.

Step S508 illustrates that the temperature value Tkorr determined in steps S506 or S507 is used for the further control or regulation of the refrigeration system 10 by the control unit 50 .

The control device 50 can also be set up to determine an expected pressure value pew based on a temperature value Tef detected by the sensor arrangement pT2, for example, and as a function of the specific material values SW of the refrigerant. For this purpose, too, the pressure value pef is recorded in step S501, for example. Furthermore, according to step S502, the temperature value Tef is detected.

According to step S513, the pressure value pew to be expected is determined based on the recorded temperature Tef and as a function of the specific material values SW. In this case, for example, in particular for an overcritical system state, the expected pressure value pew can be determined on the basis of a density characteristic for the refrigerant based on the detected temperature value Tef. Alternatively, for the subcritical state, the pressure pef to be recorded is determined from the recorded temperature Tef, based on the given pressure and temperature relationships on the boiling/dew point line or within the two-phase area

The control device 50 can also be set up to compare the expected pressure value pew with the pressure value pef detected by the sensor arrangement pT2 and to calculate a pressure value deviation pdiff. According to step S514, it can therefore be determined how large the difference or the deviation pdiff is between the detected pressure pef and the pressure pew to be expected.

The control device 50 can also be set up to store the pressure value deviation pdiff and to calculate a corrected pressure value pkorr for each recorded pressure value pef.

According to a step S515, it can be checked whether the pressure deviation pdiff is within a tolerance range or a tolerance range, which can be defined by a lower limit value pug and an upper limit value pog. For the pressure deviation pdiff, pug can be -0.1 to -0.2 bar, for example, and pog can be +0.1 to +0.2 bar. Depending on the refrigerant used, the tolerance ranges within the tolerance bands for the lower and upper limit values pug or pog can also vary in size. For example, with R744 a pressure loss of 0.1 bar means a temperature change of 0.1 K, whereas with R1234yf the same pressure jump results in a temperature change of around 1K.

If the pressure deviation pdiff is within the limit values pug and pog, step S516 determines that the corrected pressure value pkorr corresponds to the detected pressure value pef. In this case, the recorded pressure value pef is not corrected.

If the pressure deviation pdiff is outside the limit values pug or pog, the corrected pressure value pkorr is calculated in step S517, the detected pressure value pef being corrected by the pressure deviation pdiff.

Step S518 illustrates that the pressure value pkorr determined in steps S516 or S517 is used for the further control or regulation of the refrigeration system 10 by the control unit 50 .

The control device 50 can also be set up to determine, as a function of a plurality of determined temperature value deviations Tdiff and pressure value deviations pdiff, whether the associated pressure sensor or the associated temperature sensor detects fewer values to be corrected. In other words, the control device can be used to determine in step S520 which of the two sensors is working more reliably or which one is working more reliably.

Measurement results are recorded that lead to a smaller deviation from an expected value.

In this context, the control device can also be set up to use the detected value of one sensor, which requires less correction, as the basis for correcting the detected value of the other sensor. In other words, according to a step S521, the control device 50 can determine which of the recorded values pef or Tef is used without correction in order to calculate the correction value pkorr or Tkorr for the other recorded value based on the specific material values SW.

Control device 50 may also be set up to regularly check the at least one sensor arrangement, such as pT2, for example, during the service life of motor vehicle 100 while the motor vehicle is stationary, and to calculate pressure values pef detected by sensor arrangement pT as a function of a measured To correct ambient temperature Tum and specific material values SW of the refrigerant, such that a corrected pressure value pkorr is available for controlling the refrigeration system. In other words, the steps S513 to S517 described above can be run through, not using the detected temperature Tef of the refrigerant, but the detected ambient temperature Tum, which is illustrated by step S502a, for example by using the detected ambient temperature Tum for the further calculation of pkorr is included in the process as the recorded temperature Tef.

In a further application, the control device 50 can also be set up to include the ambient temperature Tum and the refrigerant temperature Tef detected by a sensor in the evaluation and to use it specifically for the verification of a complete and clean conditioning of the vehicle 100 and thus of the refrigeration circuit 10 . If the ambient temperature Tum and the detected refrigerant temperature Tef are at the same level, conditioning is complete and the sensor value can be corrected in the idle state. The sensor comparison between the environment and the refrigerant can thus be used as a fulfillment criterion for the prerequisite for carrying out a calibration or correction.

In this context, the control device 50 can also be set up to record a period of time during which the vehicle 100 or the refrigeration system 10 was not in operation. Depending on this period of time, an assumption or a decision can be made as to whether the cold on position and the refrigerant in it has essentially reached the ambient temperature. This period of time can be one to several hours or even days, etc., for example.

If one assumes that the detection of the ambient temperature Tum by means of a separate temperature sensor is reliable, it is also conceivable to run through the steps S504 to S507 described above based on the detected ambient temperature, with the expected temperature Tew of the refrigerant being equated with the detected temperature ambient temperature tum. Accordingly, after the vehicle has been stationary for a longer period of time, the detected ambient temperature Tum could be used to recalibrate both the temperature sensor and the pressure sensor.

3 shows a further example of a refrigeration system 10 in a simplified schematic representation. In this example, the refrigeration system 10 has a first heat exchanger 18, which serves as a condenser or gas cooler. Furthermore, it has a second heat exchanger 40, which is used for further cooling or supercooling of the refrigerant. A refrigerant collector 19 is arranged between the first heat exchanger 18 and the second heat exchanger 40 . Furthermore, a sensor arrangement pT4 is arranged downstream of the refrigerant collector 19 and upstream of the second heat exchanger 40 . Such a structure of a refrigeration system 10 can also be used to recalibrate the sensor arrangement pT4 or the pressure or temperature sensors used, as described above with reference to FIG 2 has been described. In particular, the refrigerant is present in two phases in the area between the refrigerant collector 19 and the second heat exchanger 40 at most operating points. Also the refrigeration system 10 of 3 includes a control device 50, which is shown in simplified form as a rectangle, by means of which the refrigeration system can be controlled or regulated accordingly.

If the refrigeration system 10 has, for example, an externally controllable expansion element AE2 and, at the same time, a described pressure/temperature sensor pT4 arranged downstream of the outer heat exchanger 18 (itself designed as a combination sensor or separately), a system condition ( short-term) are created or brought about, which temporarily make it possible to carry out a calibration at a position that initially appears unsuitable, by shifting the operating point of the system in a targeted manner in the direction of the boiling line or the two-phase area. The direct connection between pressure and temperature is automatically set and the sensor adjustment is made possible.

The same procedure can be used, for example, for a low-pressure-side sensor pT3 for setting or monitoring overheating downstream of an evaporator 22 . A targeted, forcible opening of the expansion element AE2 eliminates any required overheating and shifts the operating point to the dew line or into the two-phase area, thus creating the required connection between pressure and temperature for sensor calibration.

Consequently, in addition to a "free" or automatic calibration, a forced calibration can take place, in each case during operation of a refrigeration system 10.

QUOTES INCLUDED IN DESCRIPTION

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

Patent Literature Cited

• DE 102007010647 A1 [0002]
• JP2005106380A [0003]
• WO 2020148270 A1 [0004]

Claims (14)

Motor vehicle (100), in particular at least partially electrically driven motor vehicle, with a refrigeration system (10), the refrigeration system (10) having a refrigerant compressor (12), at least one heat exchanger (18, 22, 26, 28) and at least one sensor arrangement (pT2) has, wherein the sensor arrangement (pT2) has at least one pressure sensor and at least one temperature sensor or at least one combined pressure/temperature sensor (pT2) and wherein the sensor arrangement (pT) is arranged in a region (24.1) of the refrigeration system (10) in which the refrigerant is present in two phases or just in one phase lying on the boiling or dew line; a control device (50) which is set up to control the operation of the refrigeration system (10), characterized in that the control device (50) is set up to monitor the at least one sensor arrangement (pT2) during the service life of the motor vehicle (100). the operation of the motor vehicle (100) or during the operation of the refrigeration system (10) and the pressure values (pef) and/or temperature values (Tef) recorded by the sensor arrangement (pT2) as a function of specific material values (SW) of the used To correct refrigerant, such that for the control of the refrigeration system (10) a corrected temperature value (Tkorr) and / or a corrected pressure value (pkorr) are available. Motor vehicle (100) according to claim 1 , characterized in that the refrigeration system (10) has a low-pressure-side refrigerant reservoir (24), wherein the sensor arrangement (pT2) is arranged downstream of the refrigerant reservoir (24) and upstream of the refrigerant compressor (12). Motor vehicle (100) according to claim 1 , characterized in that the refrigeration system (10) has a first heat exchanger (18), which serves as a condenser or gas cooler, and a second heat exchanger (40), which serves for further cooling or supercooling of the refrigerant, wherein between the first and a refrigerant collector (19) is arranged on the second heat exchanger (18, 40), and wherein the sensor arrangement (pT4) is arranged downstream of the refrigerant collector (19) and upstream of the second heat exchanger (40). Motor vehicle (100) according to one of the preceding claims, characterized in that the control device (50) is set up based on a pressure value (pef) detected by the sensor arrangement (pT2, pT4) and as a function of the specific material values (SW) of the refrigerant to determine an expected temperature value (Tew). Motor vehicle (100) according to claim 4 , characterized in that the control device (50) is set up to compare the temperature value (Tew) to be expected with the temperature value (Tef) detected by the sensor arrangement (pT2, pT4) and to calculate a temperature value deviation (Tdiff). Motor vehicle (100) according to claim 5 , characterized in that the control device (50) is set up to store the temperature value deviation (Tdiff) and to calculate a corrected temperature value (Tkorr) for each detected temperature value (Tef). Motor vehicle (100) according to one of the preceding claims, characterized in that the control device (50) is set up based on a temperature value (Tef) detected by the sensor arrangement pT2, pT4) and as a function of the specific material values (SW) of the refrigerant to determine an expected pressure value (pew). Motor vehicle (100) according to claim 7 , characterized in that the control device (50) is set up to compare the expected pressure value (pew) with the pressure value (pef) detected by the sensor arrangement (pT2, pT4) and to calculate a pressure value deviation (pdiff). Motor vehicle (100) according to claim 8 , characterized in that the control device (50) is set up to store the pressure value deviation (pdiff) and to calculate a corrected pressure value (pkorr) for each recorded pressure value (pef). Motor vehicle (100) according to one of Claims 4 until 6 and one of the Claims 7 until 9 , characterized in that the control device (50) is set up to determine, depending on a plurality of determined temperature value deviations (Tdiff) and pressure value deviations (pdiff), whether the associated pressure sensor or the associated temperature sensor detects fewer values to be corrected. Motor vehicle (100) according to claim 10 , characterized in that the control device (50) is set up to use the detected value (Tef, pef) of one sensor, which requires less correction, as a basis for correcting the detected value (Tef, pef) of the other sensor. Motor vehicle (100), in particular at least partially electrically driven motor vehicle, with a refrigeration system (10), the refrigeration system (10) having a refrigerant compressor (12), at least one heat exchanger (18, 22, 26, 28, 40) and at least one sensor arrangement ( pT2, pT4), wherein the sensor arrangement (pT2, pT4) has at least one pressure sensor and at least one temperature sensor or at least one combined pressure/temperature sensor (pT2, pT4) and wherein the sensor arrangement is arranged in a region of the refrigeration system (10), in which the refrigerant is present in two phases or just in one phase lying on the boiling or dew line; a control device (50) which is set up to control the operation of the refrigeration system (10), characterized in that the control device (50) is set up to, during the service life of the motor vehicle (100), the at least one sensor arrangement (pT2, pT4 ) while the motor vehicle is stationary, in particular to regularly check and to correct the pressure values recorded by the sensor arrangement (pT2, pT4) as a function of a measured ambient temperature (Tum) and of specific material values (SW) of the refrigerant used, such that for the control of the refrigeration system (10) a corrected pressure value (pkorr) is available. Method (500) for operating a refrigeration system (10) in a motor vehicle (100), in particular in an at least partially electrically driven motor vehicle, the refrigeration system (10) having a refrigerant compressor (12), at least one heat exchanger (18, 22, 26, 28 , 40) and at least one sensor arrangement (pT2, pT4), the sensor arrangement (pT2, pT4) having at least one pressure sensor and at least one temperature sensor or at least one combined pressure/temperature sensor (pT2, pT4) and the sensor arrangement in one area the refrigeration system (10) is arranged in which the refrigerant is present in two phases or just in one phase lying on the boiling or dew line; characterized in that in the method (500) during the service life of the motor vehicle (10), the at least one sensor arrangement (pT2, pT4) is checked, in particular regularly, during operation of the motor vehicle (100) or during operation of the refrigeration system (10) (S504 , S505, S514, S515) and pressure values (pef) and/or temperature values (Tef) recorded by the sensor arrangement (pT2, pT4) depending on specific material properties (SW) of the refrigerant used are corrected (S506, S507, S516, S517 ), such that a corrected temperature value (Tkorr) and/or a corrected pressure value (pkorr) are provided (S508, S518) for the control of the refrigeration system (10). Method (500) for operating a refrigeration system (10) in a motor vehicle (100), in particular in an at least partially electrically driven motor vehicle, the refrigeration system (10) having a refrigerant compressor (12), at least one heat exchanger (18, 22, 26, 28 , 40) and at least one sensor arrangement )pT2, pT4), the sensor arrangement (pT2, pT4) having at least one pressure sensor and at least one temperature sensor or at least one combined pressure/temperature sensor (pT2, pT4) and the sensor arrangement in one area the refrigeration system (10) is arranged in which the refrigerant is present in two phases or just in one phase lying on the boiling or dew line; characterized in that in the method (500) during the service life of the motor vehicle (10), the at least one sensor arrangement (pT2, pT4) is checked, in particular regularly (S504, S505, S514, S515) while the motor vehicle (10) is stationary, and by the pressure values (pef) recorded by the sensor arrangement (pT2, pT4) as a function of a measured ambient temperature (Tum; S502a) and of specific material values (SW) of the refrigerant used are corrected (S506, S507, S516, S517) such that for the control a corrected pressure value (pkorr) is provided to the refrigeration system (10) (S508, S518).

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