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 can be connected 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 regulator (26) which is arranged in the secondary branch; at least one movable thermostatic valve (34L, 34R) which is closed The invention relates to a reheating method comprising: a first air conditioning unit (14) and a second air conditioning unit (22) arranged upstream or downstream of a heating regulator (26) in the direction of flow (L) of the supply air; at least one shut-off device (AE4, A1; R3; R4) arranged in the secondary branch (16) downstream of the heating regulator (26); wherein the reheating method comprises the following steps: adjusting the at least one shut-off device (AE4, A1; R3; R4) to a position in which the refrigerant flows into the evaporator (22) downstream of the heating regulator (26) while bypassing an external heat exchanger (18).

Description

Technical Field

[0001] The invention relates to a reheating method (RH I) 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 upstream or downstream of 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 patent documents EP 0 989 003 A2, DE 10 2006 002 233 A1 and DE 10 2016 008 743 B3.

[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, which absorbs the output 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 an 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 14. 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] The at least one shut-off member is adjusted to a position in which the refrigerant flows downstream of the heating controller into the evaporator while bypassing the external heat exchanger.

[0019] In this way, a reheating operation or reheating mode is achieved by a very compact connection of the refrigeration system with a minimum number of active components.

[0020] In the reheating method, the ambient temperature may be detected, and when the ambient temperature is below 15°C, particularly within a range of about 5°C to 15°C, the method may be performed.

[0021] This ensures that a compact connection of the refrigeration system takes place when the operating and ambient conditions are favourable for such a reheating operation.

[0022] The temperature of the supply air can be measured after it has passed through the evaporator, wherein a setpoint temperature for the temperature of the supply air after it has passed through the evaporator can be set as a function of a dehumidification requirement and / or a heating power and / or a heating requirement. In this case, the corresponding control variable or control parameter can be preset by an air conditioning controller, via which the temperature of the vehicle interior is controlled or regulated. For example, the dehumidification requirement can be determined by ambient conditions in the interior conditions.

[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 the dehumidification demand and / or heating demand determined according to the refrigeration system parameters, the setpoint temperature is gradually reduced or gradually increased until a predetermined pressure level is generated on the high-pressure side of the heating condenser and / or until the maximum or minimum setpoint temperature is adjusted. If the setpoint temperature is increased, the corresponding control parameters for the dehumidification demand (dehumidification prerequisite) can be checked in addition.

[0027] The setpoint temperature of the conditioned air after the evaporator is also referred to as the setpoint change of the air temperature after the evaporator. Here, for example, the setpoint temperature can be adjusted to a minimum of 2°C to 4°C to prevent evaporator icing due to condensation water from the evaporator supply air flow.

[0028] If the desired temperature to be reached of the air is lowered after the evaporator, more strongly cooled air is provided, and accordingly more or less cooled air can be provided at the heating regulator, so that the desired blow-out temperature of the conditioned interior supply air can be achieved, in particular by correspondingly opening or closing at least one thermostatic valve.

[0029] After reaching a predetermined pressure level, at least one shut-off device can be adjusted so that the refrigerant flows through the external heat exchanger downstream of the heating regulator before flowing through the evaporator. In particular, a transition or switchover from the reheating method described here to another reheating method is initiated.

[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 amount of feed air supplied to the evaporator can be adjusted in order to influence the heating power. In this case, the state or quality of the feed air can be adjusted, in particular fresh air or recirculated air or a mixture of fresh air and recirculated air can be supplied as feed air. In this case, recirculated air can be taken from the interior of the vehicle and fresh air can be taken from the vehicle environment.

[0032] A refrigeration device for a motor vehicle is also proposed, the refrigeration device comprising:

[0033] a refrigerant compressor connected or connectable to the primary branch and the secondary branch;

[0034] an external heat exchanger arranged in the primary branch;

[0035] an evaporator arranged in the primary branch;

[0036] a heating regulator arranged in the secondary branch;

[0037] 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;

[0038] at least one shut-off device, which is arranged in the secondary branch downstream of the heating regulator;

[0039] wherein the refrigeration device is designed to operate according to the above-mentioned reheating method, and

[0040] In this reheating operation, the refrigerant flows from the refrigerant compressor, bypassing the external heat exchanger, in sequence through the following components of the refrigeration system: the heating controller in the secondary branch, the evaporator in the primary branch.

[0041] Depending on the system topology, the external heat exchanger can be ventilated unidirectionally or bidirectionally. This allows air heat pump operation with the aid of a refrigeration system.

[0042] 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.

[0043] 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.

[0044] 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 or absorb heat from the (ambient) air.

[0045] 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

[0046] 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:

[0047] Figure 1 A schematic and simplified circuit diagram of a refrigeration system for a motor vehicle is shown;

[0048] 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;

[0049] 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;

[0050] 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

[0051] 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.

[0052] 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.

[0053] A stop valve A4 is arranged downstream of the compressor 12. An expansion valve AE2 is provided upstream of the evaporator 22.

[0054] 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 .

[0055] 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 regulator 26.

[0056] 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 (Zweig) 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 5 downstream. Here, the secondary branch 16 or the reheating branch 16.2 opens into the primary branch 14 at the branch point Ab2.

[0057] The refrigeration device 10 comprises a further evaporator or chiller 28. The chiller 28 is arranged in parallel with the evaporator 22 in terms of flow technology. 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.

[0058] 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.

[0059] In addition, Figure 1 Check 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.

[0060] The refrigeration unit 10 can be operated in different modes as briefly described below.

[0061] 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.

[0062] 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 the 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.

[0063] In the heating operation of the refrigerant circuit 11 , the shutoff valve A4 is closed and the shutoff valve A3 is opened, so that hot refrigerant can flow into the heating branch line 16 . 1 .

[0064] 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.

[0065] 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 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.

[0066] An indirect delta connection can be realized by the fact that, when the shut-off valve A1 is open, the refrigerant compressed by the refrigerant compressor 12 is expanded into the chiller 28 by means of the expansion valve AE1, wherein at the same time no mass flow is generated on the coolant side, i.e. in the coolant circuit 28.2, i.e., for example, a fluid used as a coolant, such as water or a water-glycol mixture, remains on the coolant side of the chiller 28 or the chiller 28 is not actively (actively) flowed through by the coolant. The expansion valves AE2, AE3 and AE4 remain closed in these connection variants.

[0067] 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.

[0068] 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 ). The thermostatic valves 34L, 34R can be adjusted 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 thermostatic valves 34R, 34L downstream of the heating regulator 26.

[0069] In the 100% position, the entire supply air flow L through the evaporator 22 is guided and heated before it can flow into the passenger compartment of the vehicle through the heating regulator 26. 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.

[0070] In the x-positions of the temperature control valves 34L and 34R with 0% < x < 100%, these temperature control valves are only partially open, such that only a partial air flow of the supply air flow L flowing through the evaporator 22 is respectively guided past 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 halfway, i.e. 50%.

[0071] The reheating or reheat operation of the refrigerant circuit 11 or the refrigeration device 10 is carried out in different ways according to the heat balance.

[0072] The following is based on Figure 2 the flow chart of and with reference to the refrigeration device 10 and its components shown in Figure 1 exemplarily explains a possible operating method 500 for the reheating or reheat operation. This operating method is generally implemented as a control program in a controller for a refrigeration device or air conditioning in a vehicle.

[0073] Considering the reheat 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, such that the refrigerant can flow into the evaporator 22 via the expansion valve AE2. The expansion valves AE3 and AE1 are also closed. Thus, the reheat operation is achieved with the connection of the refrigeration device 10 with as few activated components as possible.

[0074] According to the reheat method 500 shown in Figure 2 a transition to the reheat operation is achieved at a moment not shown in detail here during the operation after the start (S501) of the refrigeration device 10, which reheat operation is designated here as reheat (Reheat) I (S502). For example, a possible condition that must be met in order to start the reheat operation (S502) can be the measured ambient temperature. In particular, when the ambient temperature reaches 15 °C, especially in the range of about 5 °C to 15 °C, the reheat method can be activated.

[0075] In the reheat method 500, in this application case the two temperature control valves 34L, 34R are adjusted to the rated open position TKso. TKso can be a specific open value or can be - as in Figure 2As shown at 502a in FIG. 10 , the range from the upper opening limit TKo to the lower opening limit TKu is as shown in FIG. 10 . When the refrigeration device 10 is in operation, at least one refrigeration device parameter determines whether the heating demand remains unchanged, increases or decreases. The variable or refrigeration device parameter used as an example here is the required temperature control valve opening on the control unit side. TKan. 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. For the following description, it should be pointed out 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 considered here.

[0076] 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.

[0077] 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 (yet) closed further. Instead, the rated temperature of the supply air L discharged at the evaporator 22 is increased in step S507. In other words, the rated temperature is adjusted for the temperature of the supply air L after it has passed through the evaporator 22, depending on the heating power or the heating demand. By increasing the rated temperature at the evaporator 22, an influence is exerted on the pressure and temperature of the refrigerant, in particular in the heating regulator 26 in the refrigeration cycle 11, wherein the pressure pHD decreases when the rated temperature at the evaporator 22 increases (S508).

[0078] In step S509, it is checked whether the required thermostatic valve opening TKan is less than the lower opening limit value TKu. If this is the case, it is checked in S512 whether the setpoint temperature of the supply air discharged at the evaporator 22 has been adjusted to a maximum value, which is caused by the required dehumidification determined by the controller and / or the maximum permissible upper limit. If the maximum adjustable setpoint temperature is reached, the reheating method Reheat I is terminated and a switch is made to another reheating method, which is denoted here by RH III (step S513).

[0079] In addition, in step S512a, it is evaluated for further system safety whether the maximum pressure pHD or the maximum hot gas temperature tHG is reached. In particular, in the case of a severe dynamic closing of the thermostatic valves 34L, 34R, a branch is made to S513 and thus to another reheating connection, the so-called Reheat III.

[0080] It is also conceivable to first further increase the set point of the air temperature after the evaporator according to method step S507. However, due to the system dynamics already described, a mode switch to Reheat III may appear to be the preferred measure. Therefore, this is preferably shown in the flow chart.

[0081] When switching to the reheating method RH III, the expansion valve AE4 can be opened (gradually) and the shut-off valve A1 can be closed, so that the refrigerant flows from the heating regulator 26 via the external heat exchanger 18 to the evaporator 22. As an alternative to switching to another reheating method, a regulation SYS for the operation of the refrigeration device 10 can be carried out on the system side, for example closing the thermostatic valves 34L, 34R, wherein the system characteristics of the refrigeration cycle are constantly monitored.

[0082] If the maximum adjustable target temperature has not yet been reached, the target temperature is further increased according to S507, and steps S508 and S509 are executed again. As long as the heating demand decreases, steps S507, S508, S509, S512 are repeatedly executed.

[0083] If the condition is not met in S509, a check is made in S510 whether the required thermostatic valve opening TKan is greater than the upper opening limit TKo. If this is not the case, a check is made in S511 whether the required thermostatic valve opening is in the rated range, i.e. between TKo and TKu. If this is the case, it is assumed that the set rated temperature is appropriate and can be substantially maintained (S526). Thus, the pressure pHD is kept substantially constant according to S527.

[0084] When the heating demand increases, the method is carried out 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 upper opening limit TKo, this means that the heating demand has increased and the thermostatic valves 34L, 34R must actually be opened further. However, according to the method described here, the thermostatic valves are not opened further (yet). On the contrary, in step S515, the rated temperature of the supply air discharged at the evaporator is reduced. Here, the reduction in the rated temperature can be achieved incrementally. As a result, according to S516, the high-pressure pHD in the heating regulator 26 is increased. Correspondingly, the temperature T of the refrigerant in the heating regulator 26 also increases.

[0085] In step S517, it is checked whether the high pressure applied to the refrigeration device 10 has reached the maximum value. If this is not the case, a check is performed in S518 to see whether the required temperature control valve opening TKan is greater than the upper opening limit TKo. If this is the case, a check is performed in S519 to see whether the setpoint temperature has been adjusted to the minimum possible value. If the minimum adjustable setpoint temperature has not yet been reached, branching is repeated to S515 and the setpoint temperature is further reduced.

[0086] As long as the heating demand increases, steps S515, S516, S517, S518, S519 are repeatedly performed. The minimum adjustable setpoint temperature can be 2° C. to 4° C., and in particular the minimum adjustable setpoint temperature is selected such that ice formation of the evaporator 22 due to condensate precipitation is prevented.

[0087] If it is determined in S517 that the maximum pressure pHD or the maximum hot gas temperature tHG has been reached, a branch is made to S525. S525 represents a switch or a changeover to another reheating method, denoted here by RH III. When switching to the reheating method RHIII, the expansion valve AE4 can be opened (gradually) and the shut-off valve A1 can be closed, so that the refrigerant flows from the heating regulator 26 via the external heat exchanger 18 to the evaporator 22. As an alternative to switching to another reheating method, a system-side adjustment SYS for the operation of the refrigeration device 10 can be performed, for example, a reduction in the compressor 12 and / or an adjustment of other system parameters.

[0088] If it is determined in S519 that the target temperature has been set to the minimum value, the process branches to S524 , which indicates a switch to another reheating method RH II.

[0089] As an alternative to switching to the reheating method RH II (S524), the switching on of the electric heating element 30 can be considered for the reheating method Reheat I considered here (S520). If, according to S521, the required thermostatic valve opening TKan continues to be above the upper opening limit TKo, the heating power or heat dissipation of the electric heating element 30 is further increased. If the condition in S520 is no longer met due to the reduced 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 active, which is checked in S523, then branches to steps S510 and S511, so that as the heating demand decreases or is reduced, the pressure can be adjusted by increasing the rated temperature (S507).

[0090] In addition to the above-mentioned measures for implementing the reheating method, the amount of feed air L supplied to the evaporator 22 can also be adjusted to influence the heating power. Here, the state or quality of the feed air can be adjusted, in particular fresh air or recirculated air or a mixture of fresh air and recirculated air can be supplied as feed air. Here, recirculated air can be taken from the interior of the vehicle and fresh air can be taken from the vehicle environment.

[0091] 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 RH I described. According to this embodiment, the refrigeration device 110 and 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 has no reheating branch or reheating branch (RH III) 16.2 ( Figure 1 ). Accordingly, the external heat exchanger 18 can no longer be connected in series with the heating regulator 26.

[0092] 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.

[0093] 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, an intermediate pressure level above the freezing limit can be achieved at the evaporator 22. Any other heat source connected can be operated at a low pressure level.

[0094] 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 ).

[0095] About the basis Figure 3 and Figure 4 It 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.

[0096] 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.

[0097] The reheating method described within the scope of the present application can be realized by connecting a minimum number of components of the refrigeration device 10, 110. This also provides the possibility of allowing for a simplified design of the refrigeration device 110.

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) which is connected or connectable 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; 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 supply air; at least one shut-off device (AE4, A1; R3; R4), which is arranged in the secondary branch (16) downstream of the heating regulator (26); Wherein, the reheating method comprises the following steps: The at least one shut-off element (AE4, A1; R3; R4) 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), wherein the reheating method is characterized by the following steps: measuring the temperature of the supply air after it has passed through the evaporator (22), and adjusting a setpoint temperature (SP T_Verd) for the temperature of the supply air after it has passed through the evaporator (22) according to a dehumidification requirement and / or a heating power and / or a heating requirement; adjusting at least one of the thermostatic valves (34L, 34R) to a setpoint opening position (TKso) which is within a range from an upper opening limit value (TKo) to a lower opening limit value (TKu); When the required opening position (Tkan) is less than the lower opening limit value (TKu) or greater than the upper opening limit value (TKo), the rated opening position (TKso) of the thermostatic valve (34L, 34R) is maintained; While maintaining the setpoint open position (TKso), the setpoint temperature (SP T_Verd) is gradually reduced or gradually increased based on a heating demand determined according to refrigeration system parameters until a predetermined pressure level is generated on the high-pressure side of the heating regulator (26) and / or until a maximum or minimum setpoint temperature (SP T_Verd) is adjusted.

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 2, wherein: The method is performed when the ambient temperature is detected and is within the range of 5°C to 15°C.

4. The reheating method (500) according to claim 1 or 2, wherein: After reaching a predetermined pressure level, at least one shut-off element (AE4, A1) is opened so that the refrigerant flows through the external heat exchanger (18) downstream of the heating regulator (26) before flowing through the evaporator (22).

5. 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%.

6. The reheating method (500) according to claim 5, wherein: The setpoint opening position (TKso) of the thermostatic valve (34L, 34R) is adjusted to a value between 70% and 85%.

7. The reheating method (500) according to claim 1 or 2, wherein: The amount of feed air (L) delivered to the evaporator is adjusted in order to influence the heating power.

8. The reheating method according to claim 7, wherein: Adjust the state or quality of the incoming air, delivering fresh air or recycled air or a mixture of fresh air and recycled air.

9. A refrigeration device (10) for a motor vehicle, the refrigeration device comprising: a refrigerant compressor (12) which is connected or connectable 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 supply air; at least one shut-off device (AE4, A1; R3; R4) arranged in the secondary branch (16) downstream of the heating regulator (26); The refrigeration device (10) has a controller which is designed to operate the refrigeration device (10) in a reheating method according to any one of the preceding claims, and In this reheating operation, the refrigerant flows from the refrigerant compressor (12) through the following components of the refrigeration system (10) in sequence, bypassing the external heat exchanger (18): a heating controller (26) in the secondary branch, and an evaporator (22) in the primary branch.

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

11. The refrigeration device (10) according to claim 9 or 10, 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).

12. A motor vehicle having a refrigeration device (10) according to any one of claims 9 to 11.

Images