Method for reheating a refrigeration system for a motor vehicle, refrigeration system and motor vehicle having such a refrigeration system

Abstract

The invention relates to a reheating method (500) for operating a refrigeration device (10) for a motor vehicle, wherein the refrigeration device (10) comprises: a refrigerant compressor (12) which is connected or connectable to a primary branch (14) and a secondary branch (16); an external heat exchanger (18) which is arranged in the primary branch (14); an evaporator (22) which is arranged in the primary branch (14); a heating condenser (26) which is arranged in the secondary branch (16); at least one movable thermostatic valve (34L, 34R) which is arranged between the evaporator (22) and the heating condenser (26) with respect to the flow direction (L) of the supply air; and at least one A stop valve (AE4, A1; R3, R4) is arranged in the secondary branch (16) downstream of a heating condenser (26); wherein the reheating method comprises the following steps: adjusting the at least one stop valve (AE4, A1; R3, R4) to a position in which the refrigerant flows into the evaporator (22) downstream of the heating condenser (26) while bypassing an external heat exchanger (18), and connecting at least one further heat sink arranged in parallel or in series with the evaporator (22) in terms of flow technology, in particular a chiller (28) operating as a water heat pump and / or an external heat exchanger (18) operating as an air heat pump evaporator. The invention also relates to a refrigeration device (10) and a motor vehicle having such a refrigeration device.

Description

Technical Field

[0001] The invention relates to a reheating method (RH II) for operating a refrigeration system with heat pump functionality for a motor vehicle, a refrigeration system and a motor vehicle having such a refrigeration system. Background Art

[0002] A refrigeration device with a heat pump function usually includes: a refrigerant compressor, which is connected or can be connected to a primary branch and a secondary branch; an external heat exchanger, which is arranged in the primary branch; an evaporator, which is arranged in the primary branch; a heating regulator, which is arranged in the secondary branch; at least one movable thermostatic valve, which is arranged before or after the heating regulator with respect to the flow direction of the incoming air; and at least one shut-off mechanism, which is arranged in the secondary branch downstream of the heating regulator.

[0003] Such a refrigeration device with a heat pump function is described, for example, in patent document DE 10 2018 213 232.1, which was not yet published at the time of filing the present application.

[0004] Further background information on refrigeration devices or heat pumps is disclosed, for example, in the documents DE 101 26 257 A1, DE 10 2015 010 552 B3 and DE 10 2015 012 995 B1.

[0005] In the reheating method, which is also referred to in the technical field as reheating, reheating operation, or reheating method, the air cooled and dehumidified by the evaporator during air conditioning of the vehicle interior is brought to a desired outlet air temperature by at least partial heating with the aid of a heating controller.

[0006] Here, the heating regulator is a heat source in which the heat stored in the refrigerant is output to other media, such as air, water, a water-glycol mixture, etc. When the heating regulator is directly circulated by (ambient) air as cabin supply air and absorbing the outputted heat, the heating regulator can be designed as a heating condenser or a heating gas cooler. When the heating regulator is circulated or circulated by a fluid different from (ambient) air, such as water, a water-glycol mixture or the like, the heating regulator can be designed as a fluid-heat exchanger, in which the heat stored in the refrigerant is output to the fluid. In the design scheme as a fluid-heat exchanger, further heat transfer from the heated fluid to the (ambient) air is then achieved. In this regard, indirect heating of the (ambient) air as cabin supply air flow is achieved by the fluid-heat exchanger.

[0007] In this case, at least one thermostatic valve can be used in the air flow path between the evaporator and the heating regulator (i.e. upstream of the heating regulator), which is completely closed (0% open position or closed position) when the air is to be conducted into the vehicle interior cooled and not heated. When the thermostatic valve is completely open (100% open position), substantially all of the air flow from the evaporator is conducted through the heating regulator and heated. In the case of a partially opened thermostatic valve, a portion of the air is conducted through the heating regulator and another portion of the air is conducted around the heating regulator without being heated, so that a mixture of heated and cooled air is formed downstream of the heating regulator, which mixture is then conducted into the vehicle interior. Alternatively, the adjustable thermostatic valve can also be arranged downstream of the heating regulator. Summary of the invention

[0008] The object of the present invention is to provide a reheating method which can achieve optimized operation of a refrigeration device.

[0009] This object is achieved by a reheating method having the features of claim 1, by a refrigeration device having the features of claim 9 and by a motor vehicle having the features of claim 15. Advantageous embodiments with expedient developments are given in the dependent claims.

[0010] Therefore, a reheating method is proposed for operating a refrigeration system for a motor vehicle, wherein the refrigeration system comprises:

[0011] a refrigerant compressor connected or connectable to the primary branch and the secondary branch;

[0012] an external heat exchanger arranged in the primary branch;

[0013] an evaporator arranged in the primary branch;

[0014] a heating regulator arranged in the secondary branch;

[0015] at least one movable thermostatic valve, which is arranged before or after (upstream or downstream) the heating regulator with respect to the flow direction of the supply air;

[0016] At least one blocking element is arranged in the secondary branch downstream of the heating controller.

[0017] Here, the reheating method comprises the following steps:

[0018] adjusting the at least one shut-off member to a position in which the refrigerant flows downstream of the heating controller into the evaporator while bypassing the external heat exchanger,

[0019] Integrating at least one further heat sink / heat sink which is arranged in parallel or in series with the evaporator in terms of flow technology In particular, a water chiller operating as a water heat pump evaporator and / or an external heat exchanger operating as an air heat pump evaporator is connected.

[0020] This reheating method can be used in particular when an increased heating demand is detected, which can no longer be met solely by the heat transferred to the refrigerant at the evaporator and via the compressor. By connecting at least one additional heat sink, heat can be extracted from the coolant used as a heat source, such as water, a water-glycol mixture, (ambient) air. As a result, the temperature and pressure of the refrigerant in the refrigeration system increase, so that the heating power achieved by the refrigeration system increases together with the compressor drive power. In addition, this method allows a reheating operation or reheating mode to be achieved by a compact connection of the refrigeration system with a small number of active components.

[0021] In the reheating method, the ambient temperature can be detected and the method can be performed when the ambient temperature is below 15° C., in particular in the range of about 0° C. to 15° C., i.e., up to a low ambient temperature that just still allows the operation of the refrigeration device. This ensures that the connection of the refrigeration device with the additionally connected heat sink is carried out when the operating conditions and ambient conditions are favorable for such a reheating operation.

[0022] The access to at least one further heat sink can be effected by opening an expansion valve connected upstream of the relevant heat sink. In particular, such an expansion valve can be opened stepwise or incrementally.

[0023] The reheating method may include the following additional steps:

[0024] Adjust the thermostatic valve to the rated open position;

[0025] Maintain the thermostatic valve in the rated open position;

[0026] Based on a heating demand determined from refrigeration system parameters, the expansion valve is opened or closed stepwise until a predetermined pressure level is generated on the high-pressure side of the heating condenser and / or until the expansion valve reaches a maximum or minimum opening position.

[0027] The reheating method Reheat II (RH II) proposed here can be directly based on the functionality of the reheating method Reheat I (RH I) contained in the parallel application. In this case, all the functionality of the reheating method Reheat I (RH I) can be assumed and the heating power of the system can be increased by connecting at least one further evaporator.

[0028] Thus, the reheating method can be achieved by directly affecting the refrigeration cycle while the thermostatic valve remains essentially constant or open. In this case, the reheating method described here can end when the corresponding position of the expansion valve is reached, or the operation can be switched to another reheating method.

[0029] In the reheating method, a plurality of heat sinks can be switched in combination, wherein the corresponding expansion valves of the relevant heat sinks are opened or closed.

[0030] With a maximum opening position of 100%, the setpoint opening position of the thermostatic valve can be adjusted to a value between 60% and 90%, in particular to a value between 70% and 85%.

[0031] In the reheating method, the expansion valve connected upstream of the evaporator can always be kept in an open position, which can also be adjusted or regulated as a function of the refrigeration capacity to be provided or required (dehumidification demand). In other words, in this reheating method, the evaporator is always circulated with refrigerant, regardless of which additional heat sink(s) are connected. As a result, the air to be supplied to the vehicle interior is always dehumidified.

[0032] After reaching the maximum opening position of the expansion valve of the relevant (additional) heat sink (evaporator), the electric heating module can be switched on. This allows a further increased heating demand to be responded to. The maximum opening position should have a favourable and reasonable value, which does not necessarily have to correspond to 100% opening, but can also be less than 100%.

[0033] A refrigeration device for a motor vehicle is also proposed, the refrigeration device comprising:

[0034] a refrigerant compressor connected or connectable to the primary branch and the secondary branch;

[0035] an external heat exchanger arranged in the primary branch;

[0036] an evaporator arranged in the primary branch;

[0037] a heating regulator arranged in the secondary branch;

[0038] at least one movable thermostatic valve, which is arranged before or after the heating regulator with respect to the flow direction of the supply air;

[0039] at least one shut-off device, which is arranged in the secondary branch downstream of the heating regulator;

[0040] wherein the refrigeration device is designed to operate in the above-mentioned reheating operation, and

[0041] In this reheating operation, the refrigerant flows from the refrigerant compressor in sequence through the following components of the refrigeration system: a heating controller in the secondary branch, an evaporator in the primary branch, and a heat sink arranged in parallel or in series with the evaporator in terms of flow technology, in particular a chiller operating as a water heat pump evaporator and / or an external heat exchanger operating as an air heat pump evaporator.

[0042] The external heat exchanger can be bidirectional. This allows air heat pump operation with the aid of a refrigeration system. Depending on the implemented system design and the pipe layout, the external heat exchanger can also be unidirectional.

[0043] A shutoff valve may be arranged between the heating regulator and the evaporator, and an expansion valve may be arranged between the heating regulator and the external heat exchanger. Both the shutoff valve and the expansion valve are corresponding shutoff mechanisms, which are used to perform the reheating method. In this configuration, the reheating method can be performed with the shutoff valve open and the expansion valve closed, so that the refrigerant can flow directly from the heating regulator to the evaporator.

[0044] Alternatively, a check valve can be arranged between the heating regulator and the evaporator. The check valve is also a shut-off mechanism, which is used to perform the reheating method. This check valve can realize the flow of refrigerant from the heating regulator to the evaporator, wherein the flow or backflow in the opposite direction is prevented. In addition, the external heat exchanger can be unidirectional. In this configuration of the refrigeration device, it can also be shown that the air heat pump is running, but the reheating operation cannot be realized by the series connection of the heating regulator and the external heat exchanger, because the connection or pipeline in flow technology is abandoned between the heating regulator and the external heat exchanger. In this regard, this configuration is a simplification of the refrigeration device, but it can also be operated by the reheating method.

[0045] As described above, depending on the embodiment of the refrigeration device, the external heat exchanger can be unidirectional or bidirectional. In the unidirectional variant, the refrigerant always flows through the external heat exchanger in the same direction or in the same way during the operation of the refrigeration device and in the air heat pump mode. In the bidirectional variant, the refrigerant flows through the external heat exchanger in a different direction (oppositely) than in the air heat pump mode during the operation of the refrigeration device. It should also be noted about the external heat exchanger that it - similar to the heating regulator - can not only directly (as a gas condenser or gas cooler) but also indirectly (as a fluid-heat exchanger) to the (ambient) air output heat or absorb heat from the (ambient) air.

[0046] An expansion valve can be arranged downstream of the evaporator, which expansion valve is designed to adjust the gap pressure level at the evaporator. This can prevent ice formation in the evaporator, because the pressure in the evaporator can be adjusted in such a way that ice formation due to condensation of water in the evaporator supply air flow can be excluded, while other low-pressure-side system sections can be operated at a lower pressure level.

[0047] The motor vehicle can be equipped with the above-mentioned refrigeration device. Here, the motor vehicle can be an electric vehicle in particular. In the electric vehicle, the efficient operation of the refrigeration device can save electric energy, thereby achieving a greater cruising range of the electric vehicle. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] Further advantages and details of the present invention are obtained from the following description of embodiments with reference to the accompanying drawings. The drawings show:

[0049] Figure 1 A schematic and simplified circuit diagram of a refrigeration system for a motor vehicle is shown;

[0050] Figure 2 A flow chart showing an exemplary embodiment of a reheating method, in particular with the aid of Figure 1 Refrigeration equipment as described in;

[0051] Figure 3 A schematic and simplified circuit diagram shows an embodiment of a refrigeration system for a motor vehicle for carrying out a reheating method;

[0052] Figure 4 A schematic and simplified circuit diagram shows an embodiment of a refrigeration system for a motor vehicle for carrying out a reheating method. DETAILED DESCRIPTION

[0053] exist Figure 1 1 shows schematically and in a simplified manner an embodiment of a refrigeration device 10 for a motor vehicle. The refrigeration device 10 comprises a refrigerant circuit 11 which can be operated not only in refrigeration device operation (also referred to as AC operation) but also in heat pump mode. In the embodiment shown, the refrigeration device 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 a gas cooler. In particular, in the embodiment shown, the external heat exchanger 18 can be flowed through in both directions.

[0054] The evaporator 22 is shown here as a front evaporator for a vehicle by way of example. The evaporator 22 can also represent other possible evaporators in a vehicle, such as a rear evaporator, which can be arranged parallel to each other in terms of flow technology. In other words, the refrigeration device 10 also includes at least one evaporator 22.

[0055] A stop valve A4 is arranged downstream of the compressor 12. An expansion valve AE2 is provided upstream of the evaporator 22.

[0056] Within the scope of the present description, in the entire refrigerant circuit 11 of the refrigeration device 10 , the section from the compressor 12 to the external heat exchanger 18 , to the internal heat exchanger 20 and to the evaporator 22 is referred to as the primary branch 14 .

[0057] The refrigeration device 10 further comprises a heating regulator 26 (also referred to as a heating condenser or a heating gas cooler). A stop valve A3 is arranged upstream of the heating regulator 26. A stop valve A1 is arranged downstream of the heating regulator 26. In addition, an expansion valve AE4 is arranged downstream of the heating condenser 26.

[0058] Within the scope of this description, in the entire refrigerant circuit of the refrigeration device 10, the section from the compressor 12 to the heating regulator 26, to the expansion valve AE4 and to the branch Ab2 is referred to as the secondary branch 16. The secondary branch 16 includes a heating branch 16.1, which extends from the shut-off valve A3 via the heating regulator 26 to the shut-off valve A1. In addition, the secondary branch 16 includes a reheating branch or a reheating branch 16.2, which can be fluidly connected to the heating regulator 26 upstream and can be fluidly connected to the external heat exchanger 18 downstream. Here, the secondary branch 16 or the reheating branch 16.2 opens into the primary branch 14 at the branch point Ab2.

[0059] The refrigeration device 10 comprises a further evaporator or chiller 28. The chiller 28 is arranged fluidically in parallel with the evaporator 22. The chiller 28 can be used, for example, to cool electrical components of the vehicle, but can also be used to implement a water-heat pump function by utilizing the waste heat of at least one electrical component. An expansion valve AE1 is connected upstream of the chiller 28.

[0060] The refrigeration device 10 may also have an electric heating element 30, which is designed as a high-voltage PTC heating element, for example. The electric heating element 30 is used as an additional heater for the supply air flow L guided into the vehicle interior. Here, the electric heating element 30 can be arranged in an air conditioner 32 together with the heating regulator 26 and the evaporator 22. Here, the electric heating element 30 can be arranged downstream of the heating regulator 26.

[0061] In addition, Figure 1Check valves R1 and R2 can also be seen in the figure. In addition, some sensors pT1 to pT5 for detecting the pressure and / or temperature of the refrigerant are also shown. It should be noted that the number of sensors or their arrangement is only shown here by way of example. The refrigeration device 10 can also have fewer or more sensors. In the example shown, combined pressure / temperature sensors pT1 to pT5 are shown as sensors. However, it is also conceivable that sensors separated from each other are used to measure pressure or temperature and, if necessary, can also be arranged in a spatially separated manner along the refrigerant line.

[0062] The refrigeration unit 10 may be operated in different modes as briefly described below.

[0063] In AC operation of the refrigerant circuit 11, the refrigerant compressed at high pressure flows from the refrigerant compressor 12 into the external heat exchanger 18 with the shut-off valve A4 open. From there, the refrigerant flows to the high-pressure section of the internal heat exchanger 20 and the fully opened expansion valve AE3. Via the branch point Ab1, the refrigerant can flow to the expansion valve AE2 and into the interior evaporator 22 (evaporator section 22.1). In parallel or alternatively, the refrigerant can flow into the chiller 28 (chiller section 28.1) via the branch point Ab4 and the expansion valve AE1. From the evaporator 22 and / or the chiller 28, the refrigerant flows into the collector 24 on the low-pressure side and flows back to the compressor 12 via the low-pressure section of the internal heat exchanger 20.

[0064] In AC operation, the heating branch 16.1 or the secondary branch 16 is shut off by means of the shut-off valve A3, so that the hot refrigerant cannot flow through the heating regulator 26. In order to withdraw refrigerant from the inoperative heating branch 16.1, the shut-off member A5 designed as a shut-off valve can be opened, so that the refrigerant can flow in the direction of the collector 24 through the shut-off member A5 and the non-return valve R2 while the shut-off member A2 is closed.

[0065] In the heating operation 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 line 16 . 1 .

[0066] In order to implement the heating function by means of the chiller 28 to realize the water-heat pump operation, the refrigerant compressed by means of the refrigerant compressor 12 flows into the heating regulator 26 via the open stop valve A3. At the heating regulator 26, the heat is output to the supply air flow L that is guided into the vehicle interior. The refrigerant then flows through the open stop valve A1 and the branch point Ab1. The refrigerant is expanded into the chiller 28 by means of the expansion valve AE1 to absorb the waste heat of the electrical and / or electronic components arranged in the coolant circulation circuit 28.2. In this heating function, the expansion valves AE3 and AE4 are closed, the stop valve A5 is closed, and the stop valve A2 is opened. Here, the aged refrigerant can be sucked out of the two-way branch line 14.1 or the primary branch 14 in the water-heat pump operation through the stop valve A2 and delivered to the collector 24 through the check valve R2.

[0067] In order to implement 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 into the heating regulator 26 via the open stop valve A3 for discharging heat to the supply air flow L. Subsequently, the refrigerant is expanded into the external heat exchanger 18 via the open stop valve A1 by means of the expansion valve AE3 for absorbing heat from the ambient air. The refrigerant then flows to the collector 24 via the heat pump return branch 15 and flows back to the refrigerant compressor 12. The expansion valves AE1, AE2 and AE4 remain closed here, as does the stop valve A5.

[0068] An indirect delta connection can be realized by expanding the refrigerant compressed by the refrigerant compressor 12 into the chiller 28 by means of the expansion valve AE1 when the shut-off valve A1 is open, wherein at the same time no mass flow occurs on the coolant side, i.e. in the coolant circuit 28.2, i.e., the fluid used as coolant, such as water or a water-glycol mixture, remains on the coolant side of the chiller 28 or the chiller 28 is inactively circulated by the coolant. The expansion valves AE2, AE3 and AE4 remain closed in these connection variants.

[0069] In the reheating or reheating operation, the supply air flow L delivered to the vehicle interior is first cooled and thereby dehumidified by means of the evaporator 22. With the help of the heat transferred to the refrigerant by evaporation and dehumidification and the heat delivered to the refrigerant by the compressor 12, the supply air flow L can be completely or at least partially reheated by means of the heating regulator 26.

[0070] For this purpose, the refrigeration device 10, in particular the air conditioner 32, has an adjustable, in particular controllable and swivellable thermostatic valve 34 between the evaporator 22 and the heating regulator 26. In the example shown, a left thermostatic valve 34L and a right thermostatic valve 34R are arranged (in Figure 1(which is schematically shown). The temperature control valves 34L, 34R can be adjusted between an open position called the 100% position and a closed position called the 0% position. Alternatively, it is also possible to connect the temperature control valves 34R, 34L downstream of the heating regulator 26.

[0071] In the 100% position, the entire supply air flow L through the evaporator 22 is guided and heated by the heating regulator 26 before it can flow into the passenger compartment of the vehicle. In the 0% position, the entire supply air flow L through the evaporator 22 flows into the passenger compartment in a bypass around the heating regulator 26 without heating and thus without heat absorption.

[0072] In the x position of the temperature control valves 34L and 34R with 0% < x < 100%, these temperature control valves are only partially open, such that only a respective partial air flow of the supply air flow L through the evaporator 22 is guided through the heating regulator 26. This heated partial air flow can then be mixed into the remaining, cooled and dehumidified partial air flow. The supply air flow L heated in this way is conveyed to the passenger compartment of the vehicle. For example, the 50% position means that the temperature control valves 34R and 34L are only open by half, i.e., 50%.

[0073] The reheating or re - heating operation of the refrigerant circuit 11 or the refrigeration device 10 is carried out in different ways according to the heat balance.

[0074] The following is based on Figure 2 the flow chart and with reference to the refrigeration device 10 and its components shown in Figure 1 exemplarily explains the possible operating method 500 for the reheating or re - heating operation. This operating method is generally implemented as a control program in a controller for a refrigeration device or air conditioning in a vehicle.

[0075] Considering the re - heating operation, in which the refrigerant flows from the compressor 12 via the open shut - off valve A3 to the heating regulator 26 (heating condenser or heating gas cooler). The expansion valve AE4 is closed and the shut - off valve A1 is opened so that the refrigerant can flow into the evaporator 22 via the expansion valve AE2. Technically in the flow, the chiller 28 is connected as an additional heat sink. Accordingly, the expansion valve AE1 is also in the open position. For further consideration, it is assumed that the expansion valve AE3 is closed. Thus, the re - heating operation is achieved by connecting the refrigeration device 10 with as few activated components as possible.

[0076] The chiller 28 can be connected due to a mandatory requirement on the system side based on an existing need to cool at least one high-pressure component, or as a heating requirement for generating additional heating power at the heating controller 26, which is functionally equivalent to "automatic" high-pressure component cooling.

[0077] According to Figure 2 In the reheating method 500 shown in FIG. 5 , a transition to a reheating operation is performed at a time point not shown in detail here during operation after the refrigeration device 10 is started ( S501 ), which is represented here as reheating (Reheat) II ( S502 ). For example, a possible condition that must be met in order to start the reheating operation ( S502 ) may be the measured ambient temperature. In particular, the reheating method can be activated when the ambient temperature is below 15° C., in particular about 0° C. to 15° C.

[0078] In the reheating method 500, in this application, the two thermostatic valves 34L, 34R are adjusted to the setpoint opening position TKso. TKso can be a specific opening value or can be - as in Figure 2 As shown at 502a in the figure - the range from the opening upper limit TKo to the opening lower limit TKu. When the refrigeration device 10 is in operation, it is determined by at least one refrigeration device parameter whether the heating demand remains unchanged, increases or decreases. The parameter or refrigeration device parameter used as an example here is the thermostatic valve opening TKan required by the control unit. If the required thermostatic valve opening TKan is larger, the heating demand increases. If the required thermostatic valve opening TKan is smaller, the heating demand decreases. It should be pointed out for the following description that the thermostatic valve opening TKan required on the system side does not necessarily lead to a corresponding adjustment of the real opening position or actual opening position TKis of the thermostatic valves 34L, 34R in the reheating method observed here.

[0079] As already mentioned, it is assumed that the thermostatic valve is in the real open position TKis, which is in the range from TKo to TKu. According to step S503, it is checked whether the required thermostatic valve opening TKan is less than the upper opening limit TKo and greater than the lower opening limit TKu. If this is the case, the thermostatic valve 34L, 34R can be adjusted to its real open position TKis according to step S504, which is indicated by the two arrows in step S504. Refrigeration cycle If the condition of step S503 is not met, then in S505, it is checked whether the required thermostatic valve opening is greater than the upper opening limit TKo. Outside these limits, changes may occur in the refrigeration cycle and / or the refrigeration cycle for changes in peripherals that affect the climatic conditions, and thus react to the changed requirements and boundary conditions.

[0080] If this is not the case, the required opening position TKan is less than the lower opening limit TKu (S506). This means that the heating demand is reduced and the thermostatic valves 34L, 34R must actually be closed further. However, according to the reheating method 500 described here, the thermostatic valves are not closed further. On the contrary, in step S507, it is checked whether the expansion valve AE1 connected upstream of the chiller 28 has been adjusted to the minimum value, in particular closed. If this is the case, it can be checked in S512 whether the ambient temperature T_U is higher than the predetermined comparison temperature value T_x. Depending on the check result in S512, another reheating operation is selected or the refrigeration device is switched to another reheating operation, which is marked here with RH I or RH III (S513, S514).

[0081] If the expansion valve AE1 is not adjusted to its minimum value according to step S507, it is further closed according to step S507. As a result, the volume flow Vs_Vdi provided by the compressor decreases. Accordingly, the pressure and temperature of the refrigerant also decrease (S509).

[0082] If the minimum adjustable position of the expansion valve has not been reached and the heating demand continues to decrease, which is determined by checking the conditions in S510 and S511, the expansion valve is further closed according to S508. As long as the heating demand decreases, steps S506, S507, S508, S509, S510, S511 are repeatedly performed.

[0083] In step S510, it is checked whether the required thermostatic valve opening TKan is greater than the upper opening limit TKo. If this is not the case, it is checked in S511 whether the required thermostatic valve opening is within the rated range, i.e. between TKo and TKu. If this is the case, it is considered that the adjusted position of the expansion valve AE1 is appropriate and can be substantially maintained (S526). Thus, according to S527, the pressure pHD and the hot gas temperature tHG are kept substantially constant.

[0084] When the heating demand increases, the method is performed as follows, starting from the steps S503 and S505 already mentioned above. If it is determined in S505 that the required thermostatic valve opening TKan is greater than the opening upper limit value TKo, this means that the heating demand increases and the thermostatic valves 34L, 34R actually have to be opened further. However, according to the method described here, the thermostatic valve is not opened further (yet). On the contrary, in step S515, the expansion valve AE1 is opened. By opening the expansion valve AE1, the heat transfer from the chiller 28 to the refrigeration cycle can be achieved or increased. As a result, according to S516, the volume flow Vs_Vdi provided by the compressor 12 increases. Correspondingly, the pressure and temperature of the refrigerant also increase.

[0085] In step S517, it is checked whether the high pressure pHD and / or the hot gas temperature tHG applied in the refrigeration device 10 have reached a maximum value. If this is not the case, a check is made in S518 whether the required thermostatic valve opening TKan is greater than the upper opening limit TKo. If this is the case, a check is made in S519 whether the expansion valve AE1 has been adjusted to the maximum possible opening value. If the maximum adjustable opening position of the expansion valve AE1 has not yet been reached, branching is done again to S515 and the expansion valve AE1 is opened further (step by step or incrementally).

[0086] As long as the heating demand increases, steps S515, S516, S517, S518, and S519 are repeatedly performed.

[0087] If it is determined in S517 that the maximum pressure pHD and / or the maximum hot gas temperature tHG are reached, and therefore a further power increase via the refrigeration cycle is excluded, then branch to S524. In S524, it is checked whether the electric heating element 30 is already running at full power. If this is not the case, then in S525, the electric heating element 30 is turned on or its power is increased or heat is dissipated to the cabin air flow. In addition, if according to S521, the required thermostatic valve opening TKan continues to be above the upper opening limit TKo, then the heating power or heat dissipation of the electric heating element 30 is further increased (S525). If the conditions in S521 are no longer met due to a decrease in the heating demand, the heating power or heat dissipation of the electric heating element 30 is reduced again according to S522. If the electric heating element 30 is no longer activated, which is checked in S523, then branch to steps S510 and S511, so that as the heating demand decreases or is reduced, the pressure adjustment can be achieved again by adjusting, in particular closing, the opening position of the expansion valve AE1 (S508). If the condition in S524 is met, the refrigeration device 10 is switched to another operating mode or reheating mode, which is here purely exemplarily indicated as DWP-RH (S528). However, it can be assumed that with the maximum waste heat set by the refrigeration cycle and with the maximum heating power set by the electric heater, the system can reach its heating power limit and thus operate to the limit.

[0088] In addition to the above-mentioned measures for implementing the reheating method, the reheating method Reheat I (RH I) contained in the parallel application can also be used for power variation on the evaporator. In particular, the amount of feed air L supplied to the evaporator 22 can be adjusted to influence the heating power. In this case, fresh air or recirculated air or a mixture of fresh air and recirculated air can be used as the supplied feed air. Alternatively, the setpoint temperature of the air after the evaporator can be changed to the limit values ​​defined and permitted by the controller. This variation is particularly tailored to the dehumidification requirements.

[0089] exist Figure 2 The reheating method shown in FIG. 1 is described with the example of an additionally connected chiller with its expansion valve AE1 connected upstream. It should be pointed out that the method can also be carried out with the aid of an external heat exchanger 18 and with an open or adjustable expansion valve AE3. In this case, the external heat exchanger 18 is arranged in parallel with the evaporator 22 in terms of flow technology and operates as an air heat pump evaporator. Accordingly, AE3 can also be in Figure 2 At all positions mentioned in AE1. It is also conceivable that the chiller 28 and the external heat exchanger 18 are both connected as heat sinks. Figure 2 Use the method shown in to check or adjust the opening position of AE1 and AE3 respectively.

[0090] Figure 3 The embodiment of the refrigeration device 110 is shown, and the above-mentioned reference 110 can also be performed by using this embodiment. Figure 2 The reheating method Reheat II described in the embodiment. Figure 1 The refrigeration device 10 shown in FIG. is simplified in structure. Figure 3 It can be seen that only one connection to the evaporator 22 or the chiller 28 is provided downstream of the heating regulator 26. The refrigeration system 110 does not have a reheating branch or reheating branch 16.2 ( Figure 1 ). Accordingly, the external heat exchanger 18 can no longer be connected in series with the heating regulator 26.

[0091] In order to be able to perform the above-described reheating method also with a simplified refrigeration device 110, a non-return valve R3 is arranged between the heating regulator 26 and the expansion valve AE2 or the expansion valve AE1. The non-return valve R3 enables the refrigerant to flow from the heating regulator 26 to the evaporator 22 according to the above-described reheating method, but prevents the refrigerant from flowing in the opposite direction, i.e. when the refrigeration device is operated in AC mode.

[0092] In addition, Figure 3 2 shows an expansion valve AE5 in dashed lines downstream of the evaporator 22. Such an expansion valve AE5 can be arranged in the refrigeration device 10, 110 ( Figure 1 , Figure 3 , Figure 4 ) in all the embodiments shown here, the non-return valve R1 shown is replaced. By arranging the expansion valve AE5 downstream of the evaporator 22, a gap pressure level above the freezing limit can be achieved on the evaporator 22. The various other heat sinks connected can be operated at a low pressure level.

[0093] Figure 4 A simplified refrigeration system is shown with another possible adjustment. Figure 3 In addition to the expansion valve AE3 which is also present in the refrigeration device 110, a check valve R4 can be provided, which is arranged between the internal heat exchanger 20 and the evaporator 22 or the chiller 28. The check valve R4 is passed by the refrigerant in the AC operation of the refrigeration device 110. In the heating operation, the check valve R4 prevents the refrigerant from flowing from the heating regulator 26 to the high-pressure side of the internal heat exchanger 20. Similarly, with this further simplified configuration of the refrigeration device 110, the above-mentioned reheating method ( Figure 2 ).

[0094] About the basis Figure 3 and Figure 4It should also be pointed out that with such a configuration, the switch to the further reheating method RH III shown in steps S513 and S525 cannot be realized, but a system-side adjustment SYS must be carried out.

[0095] The above reference Figure 2 The reheating method can be carried out, for example, with the following values. With the maximum opening position of 100% as a reference, TKso can be adjusted from 60% to 90%, in particular to a value between 70% and 85%. For example, TKu can be 78% and TKo can be 82%, so that TKso covers a range from 78% to 82%. The selection of suitable opening limits TKu and TKo can be selected in particular depending on the characteristics of the refrigeration device used, wherein the range from TKu to TKo should be selected very narrowly, in particular so that the quotient of TKu / TKo is greater than or equal to 0.8. For the above example of TKu=78% and TKo=82%, the quotient is calculated to be 0.95.

[0096] The reheating method described within the scope of the present application can be realized by connecting other heat sinks, such as a chiller 28 and / or an external heat exchanger 18. In this case, the possibility of a simplified design of the refrigeration device 110 is also conceivable.

[0097] In summary, the reheating method Reheat II (RH II) proposed here is a reheating operation which is developed on the reheating method Reheat I (RH I) contained in the parallel application, wherein a further evaporator and thus an additional heat sink (here for example a chiller) is connected.

[0098] However, if, instead of the "automatic" switching in of the chiller, the chiller is "forced to switch in" to meet the heating demand, that is, active battery cooling is required in terms of thermal management, then the described sequence for the staged disconnection of the chiller cannot be followed any further. The excess heating demand can then be compensated by switching to the reheating method Reheat III (RHIII) included in the parallel application.

Claims

1. A reheating method (500) for operating a refrigeration system (10) for a motor vehicle, wherein: The refrigeration equipment (10) comprises: A refrigerant compressor (12) connected to a primary branch (14) and a secondary branch (16) by means of stop valves (A3, A4); an external heat exchanger (18) arranged in the primary branch (14); an evaporator (22) arranged in the primary branch (14); A heating regulator (26) arranged in the secondary branch (16); at least one movable thermostatic valve (34L, 34R) which is arranged upstream or downstream of the heating regulator (26) with respect to the flow direction (L) of the incoming air; at least one shut-off device arranged in the secondary branch (16) downstream of the heating regulator (26); an expansion valve (AE2) connected upstream of the evaporator (22) and another expansion mechanism (AE5) arranged downstream of the evaporator (22), Wherein, the reheating method comprises the following steps: closing the stop valve (A4) assigned to the primary branch (14) and opening the stop valve (A3) assigned to the secondary branch (16); The at least one shut-off member is adjusted to a position in which the refrigerant flows into the evaporator (22) downstream of the heating regulator (26) while bypassing the external heat exchanger (18), characterized in that Connecting at least one further heat sink which is arranged in parallel with the evaporator (22) in terms of flow technology, the at least one further heat sink being a chiller (28) operating as a water heat pump evaporator, wherein the connection of the chiller (28) is achieved by opening an expansion valve (AE1) connected upstream of the chiller (28); wherein the expansion valve (AE2) connected upstream of the evaporator (22) is always kept in an open position, wherein the open position can be adjusted according to the existing pressure level; wherein the clearance pressure level on the evaporator (22) is adjusted by an expansion valve (AE5) arranged downstream of the evaporator (22); Adjust the thermostatic valve (34L, 34R) to the rated open position (TKso); Maintaining (502a) a rated open position (TKso) of the thermostatic valve (34L, 34R); Based on the heating demand determined according to the thermostatic valve opening (TKan), the expansion valve (AE1) connected upstream of the chiller (28) is gradually opened (S515) or gradually closed (S508) until a predetermined pressure level is generated on the high-pressure side of the heating regulator (26) and / or until the expansion valve (AE1) reaches the maximum or minimum opening position (S507, S519).

2. The reheating method (500) according to claim 1, wherein: The ambient temperature is detected, and when the ambient temperature is below 15° C., the method is executed.

3. The reheating method (500) according to claim 1 or 2, wherein: A plurality of heat sinks (18, 28) are connected in a combined manner by opening or closing the corresponding expansion valves (AE1, AE3) of the relevant heat sinks (18, 28).

4. The reheating method (500) according to claim 1 or 2, wherein: The setpoint opening position (TKso) of the thermostatic valve (34L, 34R) is adjusted to a value between 60% and 90%, with the maximum opening position being 100%.

5. The reheating method (500) according to claim 1 or 2, wherein: After reaching the maximum open position (S519) of the expansion valve (AE1, AE3) of the associated heat sink (18, 28), the electric heating module (30) is switched on (S525).

6. The reheating method (500) according to claim 2, wherein: The method is performed within the range of 0°C to 15°C.

7. The reheating method (500) according to claim 4, wherein: The setpoint opening position (TKso) of the thermostatic valve (34L, 34R) is adjusted to a value between 70% and 85%, with the maximum opening position being 100%.

8. A refrigeration device (10) for a motor vehicle, the refrigeration device comprising: A refrigerant compressor (12) connected to the primary branch (14) and the secondary branch (16); an external heat exchanger (18) arranged in the primary branch (14); an evaporator (22) arranged in the primary branch (14); A heating regulator (26) arranged in the secondary branch (16); at least one movable thermostatic valve (34L, 34R) which is arranged upstream or downstream of the heating regulator (26) with respect to the flow direction (L) of the incoming air; at least one shut-off device, which is arranged in the secondary branch (16) downstream of the heating regulator (26); an expansion valve (AE2) connected upstream of the evaporator (22); another expansion mechanism (AE5) arranged downstream of the evaporator (22); The refrigeration device (10) comprises a controller, which is designed to implement the reheating method according to any one of the preceding claims. In this reheating method, the refrigerant flows from the refrigerant compressor (12) in sequence through the following components of the refrigeration system (10): a heating regulator (26) in the secondary branch, an evaporator (22) in the primary branch, and a heat sink arranged in parallel with the evaporator (22) in terms of flow technology, which heat sink is a chiller (28) operating as a water heat pump evaporator.

9. The refrigeration device (10) according to claim 8, wherein: The external heat exchanger (18) can be traversed in both directions.

10. The refrigeration device (10) according to claim 8 or 9, wherein: A shut-off valve (A1) is arranged between the heating regulator (26) and the evaporator (22), wherein an expansion valve (AE4) is arranged between the heating regulator (26) and the external heat exchanger (18).

11. The refrigeration device (10) according to claim 8, wherein: A check valve (R3) is arranged between the heating regulator (26) and the evaporator (22).

12. The refrigeration device (10) according to claim 11, wherein: The external heat exchanger (18) can be traversed unidirectionally and is separated from the heating regulator (26).

13. A motor vehicle having a refrigeration device (10) according to any one of claims 8 to 12.

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