Method for compensating the fill quantity within a refrigeration system for a motor vehicle, refrigeration system with control unit for carrying out the method and motor vehicle with such a refrigeration system
Patent Information
- Authority / Receiving Office
- DE · DE
- Patent Type
- Patents
- Current Assignee / Owner
- AUDI AG
- Filing Date
- 2024-12-17
- Publication Date
- 2026-07-16
AI Technical Summary
Refrigeration systems with branched refrigerant circuits face challenges in achieving a suitable refrigerant charge balance, leading to overfilling or underfilling in circuits with different internal volumes, which complicates leakage allowance and efficiency.
A method and system that adjusts refrigerant flow using valve arrangements and control units to balance the refrigerant charge by diverting or extracting refrigerant based on temperature and pressure measurements, ensuring optimal circulation in circuits with varying volumes.
The method effectively prevents overfilling and underfilling by dynamically adjusting refrigerant distribution, maintaining efficient operation and leak allowance in refrigeration systems with varying internal volumes.
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Abstract
Description
[0001] The invention relates to a method for balancing the fill quantity within a refrigeration system for a motor vehicle with an internal combustion engine and / or an electric drive, wherein the refrigeration system has a refrigerant circuit comprising: a refrigerant compressor; a first heat exchanger, in particular an evaporator; a second heat exchanger, in particular a gas cooler or condenser; a third heat exchanger, in particular a heating coil or hot gas cooler; wherein the second heat exchanger has a larger internal volume than the third heat exchanger.
[0002] Methods for relocating refrigerants are known from the prior art. Reference is made in particular to DE 10 2016 110 443 A1 and DE 10 2015 007 565 B3.
[0003] Refrigeration systems with a branched refrigerant circuit, for example designed as an AC / heat pump system, and with switching valves, have significantly different internal volumes in the individual switchable circuits or branches, which is accompanied by differences in fill quantities in the respective connection states.
[0004] For example, if R744 (CO2) is used as a refrigerant, the static pressure (when the refrigeration system is not in operation) must be limited to a maximum value at high ambient temperatures, for example, 93 bar at 60°C according to ISO 13043. Therefore, only a specific amount of refrigerant may be filled into the refrigeration system, depending on the available internal volume, for example, 250 g of refrigerant R744 per liter of internal volume, in order to limit the static pressure to 93 bar at 60°C.
[0005] In order to increase the amount of refrigerant, it is already known to integrate compensating volumes with additional internal volume into the refrigerant circuit, whereby the compensating volume is located at a point in the refrigerant circuit where the refrigerant has the lowest possible density, i.e., in particular before the refrigerant compressor.
[0006] Typically, a primary circuit or branch containing the second heat exchanger, particularly an external gas cooler or condenser, has a larger internal volume than a secondary circuit or branch containing the third heat exchanger, particularly a heating coil or hot gas condenser. There is only a small overlap in the charge plateaus between the active primary branch with its high charge requirement, particularly 700g of refrigerant or more, and the active secondary branch with its low charge requirement, particularly 500 to 750g of refrigerant. This means that a suitable compromise charge with a leakage allowance over several years is not possible. To ensure a sufficient leakage allowance, for example 200g of refrigerant, for the active primary branch, an exemplary charge of over 900g would have to be chosen, which would then lead to overfilling of the active secondary branch.
[0007] The object underlying the invention is seen as being to provide a method for balancing the fill quantity within a refrigeration system, in which, in particular, an overfilling of the secondary circuit with smaller internal volume can be reliably reduced and a possible subsequent underfilling can be avoided.
[0008] This problem is solved by a method, a refrigeration system, and a motor vehicle with the features of the respective independent patent claim. Advantageous embodiments with expedient further developments are specified in the dependent patent claims.
[0009] A method for balancing the refrigerant charge within a refrigeration system for a motor vehicle with an internal combustion engine and / or an electric drive is proposed, wherein the refrigeration system comprises a refrigerant circuit with: a refrigerant compressor; a first heat exchanger, in particular an evaporator; a second heat exchanger, in particular a gas cooler or condenser; a third heat exchanger, in particular a heating coil or hot gas cooler; wherein the second heat exchanger has a larger internal volume than the third heat exchanger;wherein the first heat exchanger is arranged downstream of the second heat exchanger and the third heat exchanger, such that a primary circuit is formed with the second heat exchanger and the first heat exchanger, and that a secondary circuit (16) is formed with the third heat exchanger and the first heat exchanger, wherein at least one valve arrangement is arranged downstream of the refrigerant compressor, which is configured to direct a refrigerant flow from the refrigerant compressor to the primary circuit and / or to the secondary circuit, wherein an internal volume of the primary circuit is larger than an internal volume of the secondary circuit, wherein the method, with the secondary circuit active and overfilled with respect to the amount of refrigerant, comprises the following steps: recording refrigerant temperature values and / or refrigerant pressure values; - on the inlet or outlet side of the refrigerant compressor and / or - On the outlet side of the first heat exchanger, the first valve assembly is adjusted based on at least one of the measured refrigerant temperature values and / or refrigerant pressure values such that a partial mass flow of refrigerant is diverted into the primary circuit and a partial mass flow of refrigerant circulates in the secondary circuit. The setting of the first valve assembly is modified to reduce or stop the diversion of refrigerant into the primary circuit when the measured refrigerant temperature values and / or the measured refrigerant pressure values remain essentially constant for a predetermined period. This ensures that, with an activated secondary circuit that has a smaller internal volume, the amount of circulating refrigerant in the secondary circuit can be appropriately adjusted, utilizing the larger internal volume of the primary circuit.
[0010] In this method, the setting of the first valve assembly can be modified so that the transfer of refrigerant into the primary circuit is stopped if at least one of the measured refrigerant temperature values, in particular a refrigerant temperature value at the outlet of the first heat exchanger, indicates refrigerant superheating. This ensures that underfilling of the secondary circuit is prevented or that the transfer of refrigerant from the active secondary circuit into the primary circuit can be stopped in a timely manner.
[0011] In this process, if refrigerant overheating is detected, an underfilling of the secondary circuit can be counteracted by at least partially opening an additional valve in a section of the extraction line to extract refrigerant from the primary circuit into the secondary circuit. This allows refrigerant to be added to or extracted from the secondary circuit as needed, ensuring that an optimal amount of refrigerant is circulating at all times when the secondary circuit is active.
[0012] In this procedure, the setting of the secondary valve assembly in the extraction section can be modified to reduce or stop the extraction of refrigerant from the primary circuit if the measured refrigerant temperature and / or pressure values remain essentially constant for a predetermined period. This is achieved by adjusting the secondary valve assembly in a similar manner to how the primary valve assembly was previously described.
[0013] The superheating of the refrigerant can be used as a parameter, especially when a low-pressure side refrigerant collector is provided in the refrigerant circuit.
[0014] The process described above is characterized in particular by the fact that refrigerant is transferred from the secondary circuit to the primary circuit or extracted from the primary circuit to the secondary circuit based on specific refrigerant temperature values. These refrigerant temperature values change noticeably whenever refrigerant transfer or extraction is necessary.
[0015] The process can also be carried out with a high-pressure side refrigerant receiver, whereby instead of superheating the refrigerant, subcooling of the refrigerant, in particular downstream of the second heat exchanger or downstream of an optional internal heat exchanger, can be used as the relevant parameter to carry out the removal or extraction of refrigerant between the primary circuit and the secondary circuit by means of appropriate valve settings.
[0016] Also proposed is a refrigeration system for a motor vehicle with an internal combustion engine and / or an electric drive, wherein the refrigeration system comprises a refrigerant circuit with: a refrigerant compressor; a first heat exchanger, in particular an evaporator; a second heat exchanger, in particular a gas cooler or condenser; a third heat exchanger, in particular a heating coil or hot gas cooler; wherein the second heat exchanger has a larger internal volume than the third heat exchanger;wherein the first heat exchanger is arranged downstream of the second heat exchanger and the third heat exchanger, such that a primary circuit is formed with the second heat exchanger and the first heat exchanger, and that a secondary circuit is formed with the third heat exchanger and the first heat exchanger, wherein at least one valve arrangement is arranged downstream of the refrigerant compressor, which is configured to direct a refrigerant flow from the refrigerant compressor to the primary circuit and / or to the secondary circuit, wherein an internal volume of the primary circuit is larger than an internal volume of the secondary circuit, and with a control unit which is configured to carry out the method described above.
[0017] The refrigeration system may have at least one extraction line section with an associated further valve device which is designed to extract refrigerant from the inactive primary circuit into the active secondary circuit or which is designed to extract refrigerant from the inactive secondary circuit into the active primary circuit.
[0018] In the refrigeration system, at least one compensating volume device can be arranged downstream of the valve device in the secondary circuit, upstream of the third heat exchanger, and / or downstream of the third heat exchanger.
[0019] A motor vehicle with an internal combustion engine and / or an electric drive and with a refrigeration system as described above is also proposed.
[0020] Further advantages and details of the invention will become apparent from the following description of embodiments with reference to the figures. These show: Fig. 1 simplified and schematic example of a refrigeration system with a compensation volume device for a motor vehicle; Fig. 2 simplified and schematically a diagram with refrigerant temperature values in relation to a refrigerant charge quantity; Fig. 3 simplified and schematically a flowchart of a procedure for balancing the fill quantity in a refrigeration system.
[0021] In Fig. Figure 1 illustrates a simplified and schematic example of a refrigeration system 10 with a refrigerant circuit 11. The refrigeration system 10 can be part of a motor vehicle 200, represented here as a dashed rectangle.
[0022] The refrigeration system 10 comprises in the refrigerant circuit 11 a refrigerant compressor 12, a first heat exchanger 22, which is designed in particular as an evaporator or interior evaporator, and a second heat exchanger 18, which is designed in particular as an external gas cooler or condenser.
[0023] Furthermore, the refrigeration system includes a third heat exchanger 26, which is designed in particular as a heating coil or hot gas cooler.
[0024] The second heat exchanger 18 has a larger internal volume than the third heat exchanger 26, which is illustrated purely schematically or qualitatively by the different size of the rectangles.
[0025] Downstream of the refrigerant compressor 12, a valve assembly V1 is arranged, which here, for illustrative purposes only, has two shut-off valves A3 and A4. Through the valve assembly V1 or the shut-off valves A3 and A4, a refrigerant flow can be directed from the refrigerant compressor 12 to the second heat exchanger 18 and / or to the third heat exchanger 26.
[0026] From the perspective of Fig. As can be seen from Figure 1, the first heat exchanger 22 is arranged downstream of the second heat exchanger 18 and downstream of the third heat exchanger 26.
[0027] Downstream of the refrigerant compressor, the refrigerant circuit 11 has a primary circuit or primary branch 14, which contains the second heat exchanger and the first heat exchanger 22. Furthermore, the refrigerant circuit 11 has a secondary circuit or secondary branch 16, which contains the third heat exchanger 26 and the first heat exchanger 22.
[0028] In the operation of the refrigeration system 10, in a cooling mode (AC mode), the refrigerant can circulate in the primary circuit 14, with the shut-off valve A4 open and the shut-off valve A3 closed.
[0029] In the operation of the refrigeration system 10, the refrigerant can circulate in the secondary circuit 16 in heating mode, with the shut-off valve A4 closed and the shut-off valve A3 open.
[0030] The refrigeration system has a control unit 50, which is designed to set the different operating states of the refrigeration system.
[0031] Fig. Figure 2 shows a simplified and schematic diagram with three exemplary temperature curves of refrigerant at different points in the refrigeration system 10. The representation is purely qualitative with regard to the temperature values, i.e., without specific values on the vertical Y-axis. The X-axis shows, as an example, the refrigerant charge in the active secondary circuit.
[0032] The two vertical, dashed lines indicate the range within which the refrigerant quantity in the active secondary circuit, together with the volume in the refrigerant receiver 24, enables optimal operation. The left vertical line represents a transition to a possible underfilling of the secondary circuit. The right vertical line represents a transition to a possible overfilling of the secondary circuit.
[0033] The solid line shows an example of a temperature curve downstream of or on the outlet side of the refrigerant compressor 12, for example recorded by the sensor device pT1.
[0034] The dashed line shows an example of a temperature curve downstream of, or on the outlet side of, the first heat exchanger 22, which can, for example, act as a chiller in thermal contact with a coolant circuit of the vehicle. The corresponding temperature values can be recorded, for example, by the sensor device pT2.
[0035] The long dashed line shows an example of a temperature curve downstream of or on the outlet side of the internal heat exchanger 20 on the low-pressure side, or in other words, upstream of or on the inlet side of the refrigerant compressor 12, for example detected by the sensor device pT3.
[0036] In Fig. Figure 3 is a simplified and schematic flowchart illustrating a process 500 for balancing the fill volume in the refrigeration system 10. The process 50 is described below with further reference to the Fig. 1, Fig. 2 to Fig. 3 described in more detail.
[0037] Procedure 500 is performed with the secondary circuit 16 active and overfilled with refrigerant. As described above, during heating operation, the refrigerant can circulate in the active secondary circuit 16 with shut-off valve A4 closed and shut-off valve A3 open. It is assumed that the refrigerant circuit 11 contains a quantity of refrigerant that is too large for the internal volume of the secondary circuit 16, suitable for the primary circuit, and includes an additional reserve quantity (leakage allowance).
[0038] According to step S501, refrigerant temperature values and / or refrigerant pressure values are recorded. This can be done, for example, on the inlet or outlet side of the refrigerant compressor 12, in particular by means of the sensor devices pT1, pT3. Alternatively or additionally, refrigerant temperature values can be recorded on the outlet side of the first heat exchanger 22, in particular by means of the sensor device pT2.
[0039] According to step S502, the first valve device V1, in particular the shut-off valve A4, is adjusted depending on at least one of the detected refrigerant temperature values and / or refrigerant pressure values such that a refrigerant partial mass flow is diverted into the primary circuit 14 and a refrigerant partial mass flow (continues to) circulate in the secondary circuit 16.
[0040] In other words, during step S502, both shut-off valves A3 and A4 are at least partially open, allowing refrigerant to be pumped downstream of the refrigerant compressor 12 into the primary circuit 14 and the secondary circuit 16. This allows active refrigerant to be transferred to the primary circuit 14, utilizing its (larger) internal volume. The expansion valve AE1 preferably remains closed during this process.
[0041] According to step S503, the setting of the first valve device V1, in particular the shut-off valve A4, can be changed so that the release of refrigerant into the primary circuit 14 is reduced or stopped if the detected refrigerant temperature values and / or the detected refrigerant pressure values remain substantially constant for a predetermined period of time.
[0042] Such a state, in which step S503 can be performed, is shown in the diagram of the Fig. 2. This is evident with a fill quantity between approximately 720g and approximately 1000g, whereby these gram figures are not to be understood as restrictive, but merely serve to describe the functioning of the process 500 more precisely. In other words, a refrigerant quantity of approximately 720g to 1000g can be circulated in the active secondary circuit 16, including the refrigerant receiver 24, without this having a significant impact on the efficiency of the refrigeration system 10 in heating mode. In particular, it is evident from the Fig. 2 shows that with an active secondary circuit 16, in the fill quantity range, a continuous transfer of refrigerant into the primary circuit is possible until a lower limit of approximately 720g is reached.
[0043] The determination and monitoring of when fill quantity limits or limit ranges, such as approximately 720g or approximately 1000g, are reached is carried out by recording the refrigerant temperature, which changes significantly at or within these limits, so that corresponding conclusions can be drawn about the fill quantity in the active secondary circuit.
[0044] In method 500, according to step S504, the setting of the first valve assembly V1, in particular the shut-off valve A4, can be changed such that the release of refrigerant into the primary circuit 14 is stopped if at least one of the detected refrigerant temperature values, in particular a refrigerant temperature value on the outlet side of the first heat exchanger 22, indicates refrigerant superheating. This is exemplified in Fig. 2 can be seen from the dashed line if, with an exemplary fill quantity of less than approximately 720g, the refrigerant temperature after the first heat exchanger 22 increases significantly.
[0045] In procedure 500, if refrigerant overheating (S504) is detected, an underfilling of the secondary circuit can be counteracted in a further step S505 by at least partially opening a further valve device A2 in a suction line section 15 to extract refrigerant from the primary circuit 14 into the secondary circuit 16. In this process, the first valve device V1, in particular the shut-off valve A4, is set so that no more refrigerant is pumped from the refrigerant compressor 12 into the primary circuit 14.
[0046] In procedure 500, according to step S506, the setting of the additional valve device A2 in the extraction line section 15 can be changed so that the extraction of refrigerant from the primary circuit 14 is reduced or stopped if the measured refrigerant temperature values and / or the measured refrigerant pressure values remain essentially constant for a predetermined period. Alternatively, it is also conceivable that in steps S505 and S506, the expansion device AE1 is used instead of the valve device A2 in the extraction line section 15 and its setting is changed so that refrigerant is extracted from the primary circuit 14 into the secondary circuit 16.
[0047] If the extraction of refrigerant from the primary circuit 14 is continued for too long, the charge level in the secondary circuit 16 increases, potentially leading to overfilling again. This is shown in the diagram of the Fig. 2 in the area of the right vertical dashed line. If overfilling is indicated, this can be seen, for example, by the decreasing temperature values downstream of the internal heat exchanger 20 (or upstream of the refrigerant compressor 12) (long dashed line in Fig. 2) or downstream of the refrigerant compressor 12 (solid line in Fig. 2) can be determined. In such a case, step S501 can then be activated again in procedure 500 to implement the removal of refrigerant into the primary circuit 14 once more.
[0048] It is further noted that the refrigeration system 10 in the refrigerant circuit 11 in the secondary branch 16 may have at least one equalization volume device 30 upstream and / or downstream of the third heat exchanger 26. In the Fig. Figure 1 illustrates this with two expansion tanks 30b shown with dashed lines. It should be noted that the refrigeration system 10 may also have only a single expansion tank 30b, which is arranged upstream or downstream of the third heat exchanger 26. An expansion tank 30 can also be implemented by a sound attenuation unit (not shown here), in particular designed as a resonator or muffler, or by an at least partially increased diameter of refrigerant line sections in the secondary circuit 16. For the design of an expansion tank 30, reference is made to the application filed simultaneously by the same applicant entitled "Refrigeration system with secondary circuit and expansion tank arranged therein, and motor vehicle with such a refrigeration system." There, with reference to the Fig. 1 and Fig.The two described features of a balancing volume device 30 are also considered to be disclosed by reference within the scope of the present application.
[0049] The method 500 described here has been explained in particular using a refrigerant circuit 11, which has a low-pressure-side refrigerant receiver 24. It is generally known that receivers or refrigerant receivers can be arranged on the suction side or low-pressure side upstream of the refrigerant compressor 12, as well as on the high-pressure side downstream of a condenser / gas cooler or integrated within the condenser / gas cooler. The method 500 presented here can be used as intended for refrigerant circuits 11 or systems with suction-side receivers or with high-pressure-side receivers.
[0050] If a high-pressure-side refrigerant receiver (collector) is provided, the sensor device pT4 is used downstream of the heat exchanger 18 instead of the sensor devices pT1 and pT2, or alternatively, a sensor device (not shown here) is used downstream of the internal heat exchanger 20. In this case, the subcooling (instead of superheating) determined by pressure and temperature is used to determine whether the system is underfilled, overfilled, or optimal. QUOTES INCLUDED IN THE DESCRIPTION
[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature
[0000] DE 10 2016 110 443 A1
[0002] DE 10 2015 007 565 B3
[0002]
Claims
[1] Method (500) for balancing the fill quantity within a refrigeration system (10) for a motor vehicle (200) with an internal combustion engine and / or an electric drive, wherein the refrigeration system (10) has a refrigerant circuit (11) comprising: a refrigerant compressor (12); a first heat exchanger (22), in particular an evaporator; a second heat exchanger (18), in particular a gas cooler or condenser; a third heat exchanger (26), in particular a heating coil or flue gas cooler; wherein the second heat exchanger (18) has a larger internal volume than the third heat exchanger (26); wherein the first heat exchanger (22) is arranged downstream of the second heat exchanger (18) and the third heat exchanger (26) such that a primary circuit (14) is formed with the second heat exchanger (18) and the first heat exchanger (22), and that a secondary circuit (16) is formed with the third heat exchanger (26) and the first heat exchanger (22), wherein at least one valve assembly (V1, A3, A4) is arranged downstream of the refrigerant compressor (12) which is configured to to direct a refrigerant flow from the refrigerant compressor (12) to the primary circuit (14) and / or to the secondary circuit (16), wherein an internal volume of the primary circuit (14) is larger than an internal volume of the secondary circuit (16), wherein the procedure (500) with the secondary circuit (16) active and overfilled with respect to the amount of refrigerant comprises the following steps: Recording (S501) refrigerant temperature values and / or refrigerant pressure values: - on the inlet or outlet side of the refrigerant compressor (12) and / or - on the outlet side of the first heat exchanger (22), Adjusting (S502) the first valve assembly (V1, A3, A4) depending on at least one of the detected refrigerant temperature values and / or refrigerant pressure values such that a refrigerant partial mass flow is diverted into the primary circuit (14) and a refrigerant partial mass flow circulates in the secondary circuit (16), wherein the setting of the first valve assembly (V1, A3, A4) is modified (S503) such that the release of refrigerant into the primary circuit (14) is reduced or stopped when the detected refrigerant temperature values and / or the detected refrigerant pressure values remain substantially constant for a predetermined period of time. [2] Method (500) according to claim 1, wherein the setting of the first valve device (V1, A3, A4) is changed such that the release of refrigerant into the primary circuit (14) is terminated (S504) when at least one of the detected refrigerant temperature values, in particular a refrigerant temperature value on the outlet side of the first heat exchanger (22), indicates refrigerant superheating. [3] Method (500) according to claim 2, wherein, in the event of detected refrigerant overheating, an underfilling of the secondary circuit (16) is counteracted (S505) by at least partially opening a further valve device (A2) in a suction line section (15) to extract refrigerant from the primary circuit (14) into the secondary circuit (16). [4] Method (500) according to claim 3, wherein the setting of the further valve device (A2) in the extraction section (15) is changed (S506) such that the extraction of refrigerant from the primary circuit (14) is reduced or stopped when the detected refrigerant temperature values and / or the detected refrigerant pressure values remain substantially constant for a predetermined period of time. [5] Refrigeration system (10) for a motor vehicle (200) with an internal combustion engine and / or an electric drive, wherein the refrigeration system (10) has a refrigerant circuit (11) comprising: a refrigerant compressor (12); a first heat exchanger (22), in particular an evaporator; a second heat exchanger (18), in particular a gas cooler or Capacitor; a third heat exchanger (26), in particular heating coil or Heating gas cooler; wherein the second heat exchanger (18) has a larger internal volume than the third heat exchanger (26); wherein the first heat exchanger (22) is arranged downstream of the second heat exchanger (18) and the third heat exchanger (26) such that a primary circuit (14) is formed with the second heat exchanger (18) and the first heat exchanger (22), and that a secondary circuit (16) is formed with the third heat exchanger (26) and the first heat exchanger (22), wherein at least one valve assembly (V1, A3, A4) is arranged downstream of the refrigerant compressor (12) which is configured to to direct a refrigerant flow from the refrigerant compressor (12) to the primary circuit (14) and / or to the secondary circuit (16), wherein an internal volume of the primary circuit (14) is larger than an internal volume of the secondary circuit (16), and with a control unit configured to carry out the method according to any one of claims 1 to 4. [6] Refrigeration system (10) according to claim 5, wherein it has at least one extraction line section (13, 15) with an associated further valve device (A5, A2) which is configured to extract refrigerant from the inactive primary circuit (14) into the active secondary circuit (16) or which is configured to extract refrigerant from the inactive secondary circuit (16) into the active primary circuit (14). [7] Refrigeration system according to claim 5 or 6, wherein at least one compensating volume device (30) is arranged downstream of the valve device (V1, A3, A4) in the secondary circuit (16) upstream of the third heat exchanger (26) and / or downstream of the third heat exchanger (26). [8] Motor vehicle (200) with an internal combustion engine and / or an electric drive and with a refrigeration system (10) according to one of claims 5 to 7.