DE102020106625A1 - Post-heating method for operating a refrigeration system for a motor vehicle, refrigeration system and motor vehicle with such a refrigeration system - Google Patents

Abstract

A post-heating method (500) is described for operating a refrigeration system (10) with a heat pump function for a motor vehicle, the refrigeration system (10) comprising: a refrigerant compressor (12) which can be or is connected to a primary line (14) and a secondary line (16) is; an outer heat exchanger (18) which is arranged in the primary branch (14); an evaporator (22) which is arranged in the primary branch (14); a heating register (26) which is arranged in the secondary branch (16) between the Refrigerant compressor (12) and the external heat exchanger (18) arranged primary line valve (A4); a secondary line valve (A3) arranged between the refrigerant compressor (12) and the heating register (26); at least one post-heating expansion valve (AE4) which is located between the heating register ( 26) and the outer heat exchanger (18) is arranged in the secondary branch (16); the post-heating method comprising the following steps: setting the primary branch valve (A4) and the secondary branch valve Is (A3) in an at least partially open position, such that refrigerant conveyed by the refrigerant compressor (12) is conveyed both into the primary line (14) and into the secondary line (16).

Description

The invention relates to a post-heating method (RH IV) for operating a refrigeration system with a heat pump function for a motor vehicle, a refrigeration system and a motor vehicle with such a refrigeration system.

A refrigeration system with a heat pump function usually comprises a refrigerant compressor which can be or is connected to a primary branch and a secondary branch; an external heat exchanger which is arranged in the primary train; an evaporator which is arranged in the primary line; a heating register, which is arranged in the secondary line; at least one movable temperature flap which is arranged upstream or downstream of the heating register in relation to a direction of supply air flow; and at least one post-heating expansion valve which is arranged between the heating register and the external heat exchanger in the secondary branch.

Such a refrigeration system with a heat pump function is for example in the DE 10 2018 213 232 A1 described.

Further background information on refrigeration systems and heat pumps can be found, for example, in the publications DE 100 29 934 A1 , EP 1 451 031 B1 and DE 102 15 587 A1 .

In a reheating process, which is also referred to in technical jargon as reheat, reheat operation, reheat process, the air cooled and dehumidified by the evaporator is brought to a desired blow-out temperature by at least partial heating by means of the heating register when air conditioning a vehicle interior.

The heating register is a heat source in which the heat stored in the refrigerant is transferred to another medium, such as air, water, a water-glycol mixture and the like. The heating register can be designed as a heating condenser or heating gas cooler if (ambient) air flows around it directly as cabin air, which absorbs the emitted heat. The heating register can be designed as a fluid heat exchanger if a fluid other than (ambient) air, such as water, water-glycol mixture or the like, flows through or around it, the heat stored in the refrigerant being transferred to the fluid is delivered. In the case of the configuration as a fluid heat exchanger, a further heat transfer then takes place from the heated fluid to the (ambient) air. In this respect, a fluid heat exchanger indirectly heats (ambient) air as the cabin air supply.

At least one temperature flap can be used in the air flow path between the evaporator and the heating register (i.e. upstream of the heating register), which is completely closed (0% open position or closed position) when the air is to be cooled and not heated into the vehicle interior. When the temperature flap is fully open (100% open position), essentially all of the dehumidified air flow coming from the evaporator is passed over the heating register and heated. If the temperature flap is partially opened, part of the air is passed over the heating register and the other part of the air is passed around the heating register and is not heated, so that a mixture of heated and cooled air is formed downstream of the heating register, which then flows into the vehicle interior is forwarded. The adjustable temperature flap can alternatively also be arranged downstream of the heating register.

Up to now, a desired blow-out temperature has been adjusted by adjusting the temperature flap step by step, with the post-heating expansion valve being set downstream of this step-by-step setting of the temperature flap in order to achieve an optimal pressure level in the refrigeration system. However, if the temperature flap closes very quickly, for example, this can lead to undesirable pressure changes in the refrigerant circuit due to the associated rapidly decreasing heat dissipation at the heating register. The pressure in the refrigeration system rises, but at most up to a control limit of the system at a maximum permissible pressure. In connection with this, the temperature in the refrigerant and consequently in the heating register rises, although a lower need for post-heating can actually be assumed when the temperature flap is closed. This results in inefficient operation of the refrigeration system, because if the heating register is poorly ventilated and therefore if the temperature of the refrigerant rises, the dissipation of heat is difficult or impossible due to the little open or closed temperature flap.

The object on which the invention is based is seen in specifying a reheating method in which the above disadvantages can be avoided.

This object is achieved by a reheating method with the features of claim 1, by a refrigeration system with the features of claim 11 and by a motor vehicle with the features of claim 16. Advantageous embodiments with useful developments are specified in the dependent claims.

• einen Kältemittelverdichter, der mit einem Primärstrang und einem Sekundärstrang verbindbar oder verbunden ist;
• einen äußeren Wärmeübertrager, der im Primärstrang angeordnet ist;
• einen Verdampfer, der im Primärstrang angeordnet ist;
• ein Heizregister, das im Sekundärstrang angeordnet ist
• ein zwischen dem Kältemittelverdichter (12) und dem äußeren Wärmeübertrager (18) angeordnetes Primärstrangventil (A4);
• ein zwischen dem Kältemittelverdichter (12) und dem Heizregister (26) angeordnetes Sekundärstrangventil (A3);
• wenigstens ein Nachheiz-Expansionsventil, das zwischen dem Heizregister und dem äußeren Wärmeübertrager im Sekundärstrang angeordnet ist.

A post-heating method is therefore proposed for operating a refrigeration system with a heat pump function for a motor vehicle, the refrigeration system comprising:

• a refrigerant compressor which can be or is connected to a primary branch and a secondary branch;
• an external heat exchanger which is arranged in the primary train;
• an evaporator which is arranged in the primary line;
• a heating register, which is arranged in the secondary line
• a between the refrigerant compressor ( 12th ) and the external heat exchanger ( 18th ) arranged primary branch valve ( A4 );
• a between the refrigerant compressor ( 12th ) and the heating register ( 26th ) arranged secondary branch valve ( A3 );
• at least one post-heating expansion valve, which is arranged between the heating register and the external heat exchanger in the secondary branch.

• Einstellen des Primärstrangventils und des Sekundärstrangventils (A3) in einer zumindest teilweise geöffneten Stellung, derart dass von dem Kältemittelverdichter gefördertes Kältemittel sowohl in den Primärstrang als auch in den Sekundärstrang gefördert wird.

It is envisaged that the post-heating process includes the following steps:

• Setting the primary branch valve and the secondary branch valve ( A3 ) in an at least partially open position, such that refrigerant conveyed by the refrigerant compressor is conveyed both into the primary line and into the secondary line.

The method proposed here enables the heating requirement control through a parallel flow through the primary line and the secondary line. Due to the particularly infinitely variable setting of the primary branch valve and the secondary branch valve, a smooth transition can take place, for example, from pure AC operation (primary branch valve is fully open and secondary branch valve is completely closed) to post-heating operation. An abrupt transition from AC operation to after-heating operation, in which the secondary branch valve is completely open and the primary branch valve is completely closed, can thus be bypassed or prevented, so that the corresponding switching process or operation can also be simplified. In a further embodiment, the post-heating expansion valve can be at least partly opened in the post-heating method with the secondary branch valve at least partially open. This ensures that the refrigerant conducted in the secondary line to the heating register leaves the secondary line downstream of the heating register in a regulated manner, in particular can be relaxed in the direction of the external heat transfer.

When the primary branch valve is fully open, the secondary branch valve can be opened step by step, in particular when the post-heating expansion valve is simultaneously releasing a flow cross-section, in order to cover an increasing or emerging heating requirement. The secondary branch valve can be continuously adjustable and the step-by-step opening merely expresses the fact that the setting of a specific opening position can be regularly adjusted.

The secondary branch valve can remain set in an open position when the heating requirement is met. Such an open position can also be referred to as an intermediate open position.

The secondary branch valve can be closed step by step if the heating requirement drops or if there is excess heating. Correspondingly, when the secondary branch valve is closed, the post-heating expansion valve is also closed and stored refrigerant can be brought back into the active system section via a suction valve.

Starting from a state in which the secondary branch valve is completely open and the primary branch valve is at least partially open, the primary branch valve can be closed gradually in order to cover an increasing heating requirement.

The primary branch valve can remain set in one or the (intermediate) open position when the heating requirement is met.

The primary branch valve can be opened step by step if the heating requirement drops or if there is excess heating. The primary branch valve can be steplessly adjustable and the step-by-step opening merely expresses the fact that the setting of a specific opening position can be regularly adjusted.

The reheating process (Reheat IV) presented here can be completed when the primary branch valve is fully open and the secondary branch valve is fully closed, or when the primary branch valve is fully closed and the secondary branch valve is fully open. With the reheating process (Reheat IV) presented here, a transition between AC operation (primary branch valve fully open and secondary branch valve fully closed) and a differently implemented or regulated post-heating operation (with primary branch valve fully closed and Secondary branch valve fully open; the so-called Reheat I, Reheat II or Reheat III).

The partial refrigerant mass flows present in the primary branch and in the secondary branch, with the primary branch valve and secondary branch valve at least partially open at the same time, can be at least partially combined upstream of the external heat exchanger. In this way it can be achieved that the two parallel refrigerant flows are conducted as a total mass flow through the external heat exchanger and the total mass flow can be cooled.

• einem Kältemittelverdichter, der mit einem Primärstrang und einem Sekundärstrang verbindbar oder verbunden ist;
• einem äußeren Wärmeübertrager, der im Primärstrang angeordnet ist;
• einem Verdampfer, der im Primärstrang angeordnet ist;
• einem Heizregister, das im Sekundärstrang angeordnet ist
• einem zwischen dem Kältemittelverdichter und dem äußeren Wärmeübertrager angeordneten Primärstrangventil;
• einem zwischen dem Kältemittelverdichter und dem Heizregister angeordneten Sekundärstrangventil;
• wenigstens einem Nachheiz-Expansionsventil, das zwischen dem Heizregister und dem äußeren Wärmeübertrager im Sekundärstrang angeordnet ist;
• wobei die Kälteanlage dazu eingerichtet ist, mit einem Nachheizverfahren bzw. in einem Nachheizbetrieb, wie es bzw. er oben beschrieben worden ist, betrieben zu werden.

A refrigeration system with a heat pump function for a motor vehicle is also proposed

• a refrigerant compressor which can be or is connected to a primary branch and a secondary branch;
• an external heat exchanger which is arranged in the primary train;
• an evaporator which is arranged in the primary line;
• a heating register, which is arranged in the secondary line
• a primary branch valve arranged between the refrigerant compressor and the external heat exchanger;
• a secondary branch valve arranged between the refrigerant compressor and the heating register;
• at least one post-heating expansion valve which is arranged between the heating register and the external heat exchanger in the secondary branch;
• wherein the refrigeration system is set up to be operated with a post-heating process or in a post-heating mode, as it has been described above.

Depending on the system topology, the external heat exchanger can have a monodirectional or bidirectional flow, depending on the design of the refrigeration system. In a monodirectional variant, the refrigerant always flows through the external heat exchanger in the same direction or in the same way in refrigeration system operation and in air heat pump mode. In a bidirectional variant, the refrigerant flows through the external heat exchanger in the refrigeration system operation in a different or different direction (opposite) than in the air heat pump mode. With regard to the external heat exchanger, it should also be noted that - similar to the heating register - it can transfer heat to or from the (ambient) air both directly (as a condenser or gas cooler) and indirectly (as a fluid heat exchanger). For the implementation of the post-heating process presented here, the external heat exchanger is flowed through by both refrigerant partial flows (primary line / secondary line) in the same direction after they have been brought together.

The refrigeration system can have a connecting section designed with an adjustable valve, the end of which on the secondary flow side is arranged downstream of the heating register and the end of which on the primary flow side is arranged upstream of the evaporator. As a result, a partial refrigerant mass flow can be conducted after the heating register to the evaporator and / or a chiller.

In this case, the end of the connecting section on the primary-flow side can be arranged upstream of an inner heat exchanger. In such an (alternative) embodiment, a refrigerant partial mass flow after the heating register can be introduced into the primary branch in such a way that it is passed through the internal heat exchanger before it flows through the evaporator and / or the chiller.

In the refrigeration system, a non-return valve can be arranged in the secondary branch downstream of the heating register. In particular, the check valve can be arranged downstream of the post-heating expansion valve. By arranging such a check valve, the inflow of refrigerant from the primary branch into the secondary branch can be avoided.

A motor vehicle can be equipped with such a refrigeration system. The motor vehicle can in particular be an electric vehicle. In the case of an electric vehicle, the efficient operation of the refrigeration system can lead to electricity savings, so that a greater range of the electric vehicle can be achieved as a result.

• 1 ein schematisches und vereinfachtes Schaltbild einer Kälteanlage für ein Kraftfahrzeug;
• 2 ein Flussdiagram einer beispielhaften Umsetzung des Nachheizverfahrens, insbesondere mittels der in 1 beschriebenen Kälteanlage.

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

• 1 a schematic and simplified circuit diagram of a refrigeration system for a motor vehicle;
• 2 a flow diagram of an exemplary implementation of the post-heating process, in particular by means of the in 1 described refrigeration system.

In 1 is an embodiment of a refrigeration system 10 for a motor vehicle shown schematically and simplified. The refrigeration system 10 includes a refrigerant circuit 11 , which both in a refrigeration system operation (also called AC operation for short), as can also be operated in a heat pump mode. The refrigeration system 10 comprises in the embodiment shown a refrigerant compressor 12th , an external heat exchanger 18th , an internal heat exchanger 20th , a vaporizer 22nd and an accumulator or refrigerant collector 24 . The external heat exchanger 18th can be designed as a condenser or gas cooler. In particular, the external heat exchanger 18th in the embodiment shown, bidirectional flow bar.

The evaporator 22nd is shown here as an example of a front evaporator for a vehicle. The evaporator 22nd also represents other evaporators possible in a vehicle, such as rear evaporators, which can be fluidically arranged parallel to one another. In other words, the refrigeration system includes 10 so at least one vaporizer 22nd .

Downstream of the compressor 12th is a particularly infinitely adjustable shut-off or expansion valve A4 arranged, the following as the primary branch valve A4 referred to as. Upstream of the evaporator 22nd is an expansion valve AE2 intended.

In the context of this description, in the entire refrigerant circuit 11 the refrigeration system 10 the section from the compressor 12th to the external heat exchanger 18th , to the internal heat exchanger 20th and to the evaporator 22nd as the primary strand 14th designated.

The refrigeration system 10 further comprises a heating register 26th (Also referred to as a heating condenser or heating gas cooler, which can enable direct or indirect heat transfer). Upstream of the heating register 26th is a particularly infinitely adjustable shut-off or expansion valve A3 arranged, the following as a secondary branch valve A3 referred to as. Downstream of the heating register 26th is a shut-off valve A1 arranged. Further is downstream of the heating register 26th an expansion valve AE4 arranged.

In the context of this description, in the entire refrigerant circuit of the refrigeration system 10 the section from the compressor 12th to the heating register 26th , to the expansion valve AE4 and to a branch Starting at 2 as a secondary strand 16 designated. The secondary strand 16 includes a heating branch 16.1 that differs from the shut-off valve A3 via the heating register 26th to the shut-off valve A1 extends. The secondary line also includes 16 a reheat branch 16.2 , the one upstream with the heating coil 26th and downstream with the external heat exchanger 5 is fluid connectable. The secondary line ends here 16 or the reheat branch 16.2 at a branch point Starting at 2 in the primary strand 14th .

The shut-off valve A1 is at a connection section 16.3 intended. The connecting section 16.3 includes a branch (or end) on the secondary side From 5 . The connecting section has on the side of the primary strand 16.3 a branch (or an end) Ab1 on. The shut-off valve A1 can also be designed as a continuously adjustable valve, in particular as an expansion valve.

In addition to the variant of the connecting section shown as a solid line 16.3 this can alternatively also be used as a connecting section 16.4 be executed, which is shown in dashed lines. The connecting section 16.4 also a branch From 5 on the secondary line 16 but is up with the primary strand 14th upstream of the internal heat exchanger 20th at a junction From 6 tied together. One such alternative is in the section between the branch points From 6 and the gas cooler 18th or capacitor 18th (external heat exchanger) to provide another lockable expansion device AE6 in order to continue to guarantee the previous functionality of the overall system. The expansion valve AE1 could also be designed as a shut-off valve in this variant. When the dashed shut-off valve A1 in the section 16.4 is designed as a lockable expansion valve AE7, with this expansion of the refrigerant in the case of an air heat pump in the gas cooler can already be achieved 18th or capacitor 18th take place. An expansion valve AE7 also allows (pre-) expansion into the chiller 28 conceivable in order to reduce the influence of the internal heat exchanger in this way 20th to reduce the water heat pump process. For the control and the holistic operation of the refrigeration system, it can be seen as technically more expedient with the alternative solution, for each heat exchanger via its own, independent expansion device AE1 and AE6.

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

The refrigeration system 10 can also be an electric heating element 30th have, which is designed, for example, as a high-voltage PTC heating element. The electric heating element 30th serves as an additional heater for a supply air flow L routed into the vehicle interior. The electrical heating element 30th together with the heating register 26th and the vaporizer 22nd in an air conditioner 32 housed be. The electrical heating element 30th the heating register 26th be arranged downstream.

In the 1 are also check valves R1 and R2 evident. Another check valve R3 can be in the secondary line 16 downstream of the heating register 26th be arranged. The check valve R3 the expansion valve AE4 be upstream or downstream. In the 1 a representation is chosen in which the check valve R3 the expansion valve AE4 is downstream. In other words, it is the check valve R3 between the expansion valve AE4 and the branch Starting at 2 arranged.

There are also some sensors pT1 until pT5 for the detection of pressure and / or temperature of the refrigerant shown. It should be noted that the number of sensors or their arrangement is shown here only as an example. A refrigeration system 10 can also have fewer or more sensors. In the example shown, the sensors are combined pressure / temperature sensors pT1 until pT5 shown. However, it is just as conceivable that sensors which are separate from one another are used for measuring pressure or temperature and, if necessary, are also arranged spatially separated from one another along the refrigerant lines.

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

In AC operation of the refrigerant circuit 11 the refrigerant, which has been compressed to high pressure, flows from the refrigerant compressor 12th with the primary branch valve open A4 and with the secondary branch valve closed A3 in the external heat exchanger 18th . From there it flows to the high pressure section of the internal heat exchanger 20th and the fully open expansion valve AE3 . Via a branch point Ab1 can the refrigerant to the expansion valve AE2 and in the interior evaporator 22nd flow (evaporator section 22.1 ). In parallel or alternatively, the refrigerant can use a branch point From 4 and the expansion valve AE1 in the chiller 28 flow (chiller section 28.1 ). From the vaporizer 22nd or / and the chiller 28 the refrigerant flows into the collector on the low-pressure side 24 and through the low pressure section of the internal heat exchanger 20th back to the compressor 12th .

The heating branch is in AC operation 16.1 or the secondary line 16 by means of the shut-off valve A3 shut off so that hot refrigerant cannot pass through the heating coil 26th can flow. To retrieve refrigerant from the inactive heating branch 16.1 can be designed as a shut-off valve A5 opened so that the refrigerant passes through the shut-off element A5 and the check valve R2 , with the shut-off element closed at the same time A2 , towards the collector 24 can flow.

In heating mode or after-heating mode in accordance with Reheat I to III modes of the refrigerant circuit 11 is the primary branch valve A4 closed and the secondary branch valve A3 opened so that hot refrigerant enters the heating branch 16.1 can flow.

To carry out the heating function using the chiller 28 in order to implement a water heat pump operation, this flows by means of the refrigerant compressor 12th compressed refrigerant via the open shut-off valve A3 in the heating register 26th . On the heating register 26th heat is given off to a supply air flow L guided into the vehicle interior. The refrigerant then flows through the open shut-off valve A1 and the branch point Ab1 . It is by means of the expansion valve AE1 in the chiller 28 for absorbing waste heat in a coolant circuit 28.2 arranged electrical and / or electronic components relaxed. The expansion valves are used for this heating function AE3 and AE4 closed, the shut-off valve A5 closed and the shut-off valve A2 opened. You can use the shut-off valve A2 Refrigerant outsourced in water heat pump operation from a bidirectional branch 14.1 or the primary line 14th sucked off and through the check valve R2 the collector 24 are fed.

To carry out the heating function by means of the external heat exchanger 18th as a heat pump evaporator, it flows by means of the refrigerant compressor 12th compressed refrigerant via the open shut-off valve A3 for the transfer of heat to a supply air flow L in the heating register 26th . Then it is over the open shut-off valve A1 by means of the expansion valve AE3 in the external heat exchanger 18th relaxed to absorb heat from the ambient air. The refrigerant then flows through a heat pump return branch 15th to the collector 24 and back to the refrigerant compressor 12th . The expansion valves AE1 , AE2 and AE4 stay with it, as well as the shut-off valve A5 , closed.

An indirect delta connection can be implemented with the shut-off valve open A1 that from the refrigerant compressor 12th compressed refrigerant by means of the expansion valve AE1 in the chiller 28 is relaxed, at the same time the coolant side, so in the coolant circuit 28.2 no mass flow is generated, for example the fluid used as a coolant, such as water or a water-glycol mixture, on the coolant side of the chiller 28 stops or the chiller 28 coolant is not actively flowing through it. the Expansion valves AE2 , AE3 and AE4 remain closed with this switching variant.

In the case of post-heating or reheat operation, the supply air flow L fed into the vehicle interior is reduced by means of the evaporator 22nd initially cooled and thus dehumidified. With the heat transferred to the refrigerant through evaporation and dehumidification and that of the refrigerant via the compressor 12th supplied heat can the supply air flow L by means of the heating register 26th completely or at least partially reheated.

For this purpose, the refrigeration system 10 , especially the air conditioner 32 , between the evaporator 22nd and the heating register 26th adjustable, in particular controllable and swiveling, temperature flaps 34 on. In the example shown, there is a left and a right temperature flap 34L and 34R (in 1 shown schematically). The temperature flaps 34L , 34R can be set or pivoted between an open position, which is referred to as the 100% position, and a closed position, which is referred to as the 0% position. Alternatively, it is also possible to use the temperature flaps 34R , 34L the heating register 26th downstream.

In the 100% position, the whole thing is the vaporizer 22nd Supply air flow L through the heating register 26th guided and heated before it can flow into the passenger compartment of the vehicle. In the 0% position, everything flows through the evaporator 22nd Supply air flow L flowing through in the bypass around the heating register 26th without heating and therefore without heat absorption in the passenger compartment.

In an x-position of the temperature flaps 34L and 34R with 0% <x <100%, these temperature flaps are only partially open, so that only a partial air flow from the evaporator 22nd incoming air flow L via the heating register 26th to be led. This heated partial air flow can then be added to the remaining, cooled and dehumidified partial air flow. The supply air flow L heated in this way is supplied to the passenger compartment of the vehicle. For example, a 50% position indicates that the temperature flaps 34R and 34L are only half open, i.e. 50%.

A post-heating or reheat operation of the refrigerant circuit 11 or the refrigeration system 10 is carried out in different ways depending on the heat balance.

The following is a possible operating method for reheating or reheating 500 using the flow chart of the 2 and with reference to the in 1 refrigeration system shown 10 and its components explained by way of example. Such an operating method is usually implemented as a control program in a control device for the refrigeration system or for air conditioning in a vehicle.

A reheating operation (Reheat IV) is considered, in which the refrigerant originates from the compressor 12th at the same time via the at least partially open secondary branch valve A3 to the heating register 26th (Heating condenser or heating gas cooler) and via the at least partially open primary branch valve A4 to the external heat exchanger 18th and flows to the evaporator. The shut-off valve is in this type of reheating operation A1 (in the connection section 16.3 respectively. 16.4 ) usually closed and the refrigerant flows in the secondary branch 16 via the expansion valve AE4 to the external heat exchanger 18th . The partial refrigerant mass flow that has been routed via the secondary branch is thereby diverted Starting at 2 in the primary strand 14th guided so that a total volume flow of refrigerant to the external heat exchanger 18th to be led.

The refrigerant then passes through the internal heat exchanger on the high pressure side 20th and passes through the open expansion valve AE3 and the expansion valve AE2 to the evaporator 22nd . From there, the refrigerant arrives via the refrigerant collector 24 and the section of the internal heat exchanger on the low-pressure side 20th back to the compressor 12th .

The temperature flaps 34L , 34R can be moved or set into suitable positions, which are indicated below with "TK", whereby TK a value of 0% (temperature flaps 34L , 34R closed) up to 100% (temperature flaps 34L , 34R fully open).

According to the in 2 post-heating method shown 500 takes place during operation after the start ( S501 ) of the refrigeration system 10 at a point in time not specified here, a transition to after-heating operation, which is here with Reheat IV ( S502 ) is designated. A possible condition that must be met in order to run after heating ( S502 ) to start, for example, a changing blow-out temperature requirement for the interior, also depending on the ambient conditions, such as the temperature. The reheating process presented here can be activated in particular when the ambient temperature is up to 25 ° C. is, in particular from about 10 ° C to 25 ° C. Furthermore, the post-heating process 500 activated when either the primary branch valve A4 is open (A4 = 100%) and the secondary branch valve A3 is still closed (A3 = 0%) (S503), or the primary branch valve A4 is still closed (A4 = 0%) and the secondary branch valve A3 is open (A3 = 100%) (S504). In the second case that is The reheating process is already active and only its effect is changed.

In the following description of the 2 Note that there is an upward arrow in the 2 an opening of the valve concerned A3 respectively. A4 illustrated. An arrow pointing downwards illustrates the throttling or closing of the valve in question A3 , A4 . If an arrow pointing upwards and an arrow pointing downwards are shown, the valve in question is A3 , A4 held in a certain or reached open position. With regard to the heating requirement Hb, an arrow pointing upwards illustrates an increasing heating requirement Hb and an arrow pointing downwards illustrates a falling or negative heating requirement or a heating surplus. Furthermore, in the 2 "Y" or "N" indicates the step to which the procedure branches if the condition is accepted ("Y") or not accepted ("N").

Assuming an AC operation in which the primary branch valve A4 open (A4 = 100%) and the secondary branch valve A3 is closed (A3 = 0%) ( S503 ), can be used in the post-heating process 500 the secondary branch valve A3 ideally be (partially) opened steplessly in small steps ( S505 ), if a (increasing) heating requirement Hb (arrow up) has been determined ( S506 ). If the procedure determines that the heating requirement has been met ( S506 in combination with S507 ), opens the secondary branch valve A3 stopped and its open position is maintained ( S508 ). Is further heating demand ( S506 ) given, the secondary flow valve A3 be opened further ( S505 ), if necessary also up to the fully open position ( S509 ). If there is excess heating or a negative heating requirement ( S507 ), the secondary flow valve can A3 be throttled ( S510 ). The throttling of the secondary flow valve A3 can take place until the status of the covered heating requirement is reached again (opening position of the secondary flow valve A3 will be maintained, S508 ) or until the heating demand increases again ( S506 ).

With reference to 1 it must be ensured that with the onset of post-heating operation RH IV also the post-heating expansion device AE4 is to be opened to allow a refrigerant flow in the secondary branch.

Is the secondary flow valve A3 fully open ( S509 ) and there is a further heating requirement, the opened primary flow valve A4 be throttled ( S511 ). Is the heating requirement when the secondary branch valve is fully open A3 covered, the primary branch valve A4 remain set in a currently reached open position. If there is further heating demand, the primary flow valve can A4 continue to be closed. If there is excess heating or a negative heating requirement, the primary flow valve can A4 be reopened. The opening of the primary flow valve A4 can take place until the status of the covered heating requirement is reached again (open position of the primary flow valve A4 is maintained) or until the heating demand increases again.

Is the secondary branch valve A3 fully open ( S509 ) and the primary branch valve A4 closed ( S512 ), the post-heating process branches off 500 (Reheat IV) to the crotch S504 .

Starting from a means of the refrigeration system 10 After-heating operation (Reheat I, Reheat II or Reheat III) that can be implemented in a system-technically different manner, in which the primary branch valve A4 closed (A4 = 0%) and the secondary branch valve A3 is open (A3 = 100%) ( S504 ), can be used in the post-heating process 500 (Reheat IV) the primary branch valve A4 be opened (again) if a heating surplus or a negative heating requirement has been determined ( S515 ). If the procedure determines that the heating requirement has been met or that there is no longer any excess heating ( S515 in combination with S516 ), the opening of the primary branch valve is activated A4 stopped and its open position is maintained ( S517 ). If there is further excess heating or a negative heating requirement ( S515 ), the primary flow valve can A4 be opened further ( S518 ), if necessary also up to the fully open position ( S519 ). If a further excess heating or a negative heating requirement is determined afterwards, it can be done with the primary branch valve open A4 ( S519 ) the secondary flow valve A3 be throttled. The throttling of the secondary flow valve A3 can take place until the status of the covered heating requirement is reached again (opening position of the secondary flow valve A3 is retained or the valve is moved until the cross-section is completely closed) or until the heating requirement increases again.

Is the primary branch valve A4 fully open ( S519 ) and the secondary branch valve A3 closed ( S520 ), the post-heating process branches off 500 (Reheat IV) to step S503 .

Whether there is a heating requirement can, for example, be carried out using a heating requirement balance. For example, a temperature sensor that monitors the heat source level during the conditioning of supply air L can be taken into account. As an alternative or in addition, the position of the temperature flaps can be used in the heating demand balancing 34L , 34R are taken into account, the position of which is in turn specified as a function of the setpoint value of the temperature of the cabin supply air flow. When operating the refrigeration system 10 it is therefore determined via at least one parameter that prescribes or determines the refrigeration system configuration whether the heating requirement is required is constant, increasing or decreasing. A variable or refrigeration system parameter used here as an example is the temperature flap opening TKan requested by a control unit, which in turn is linked to the setpoint specification of the cabin air temperature. If a larger temperature flap opening TKan is required, the heating requirement increases. If a smaller temperature flap opening TKan is required, the heating requirement is reduced. A temperature flap opening TKan requested by the system does not necessarily lead to a corresponding adjustment of the actual opening position or actual opening position TKis of the temperature flaps in the reheating method considered here (Reheat IV) 34L , 34R Instead, based on the required temperature flap opening TKan, the opening position (s) of the primary branch valve is first adjusted A4 and / or the secondary branch valve A3 performed.

With the reheating process presented here 500 (Reheat IV) is based on the determined heating requirement when the primary branch valve is open A4 and with the secondary branch valve open A3 by further opening or closing (throttling) the primary branch valve A4 and / or the secondary branch valve A3 reacts before possibly in a next step with an adjustment of the temperature flaps 34L , 34R (TKis) is responded.

The primary branch valve A4 and the secondary branch valve A3 can during the reheating process presented here 500 Take open positions from> 0% to 100% at the same time. Any combination of the primary branch valve that is open at the same time is possible A4 and the secondary branch valve A3 conceivable, for example
both 100% open or
one 100% open, the other 20% open or
one 70% open, the other 40% open or
one open 20%, the other 20% open.

The percentage opening positions listed above are only examples and are in no way a restriction.

The post-heating process 500 (Reheat IV) is activated until one of the conditions according to the steps is fulfilled S503 or S504 there is no more positive or negative heating requirement, so go through the steps S503 , S506 , S507 , S508 , S523 or S504 , S515 , S516 , S525 , S524 the procedure 500 (Reheat IV) can be ended. Starting from step S503 leads to the termination of the procedure ( S521 ) to a transition to AC operation ( S522 ). Starting from step S504 leads to the termination of the procedure ( S513 ) to a transition to another post-heating or reheat mode ( S514 ).

So that the refrigerant in the post-heating process 500 (Reheat IV) with the primary branch valve open at the same time A4 and secondary branch valve A3 can be optimally or maximally cooled, the partial refrigerant mass flows at the branch Starting at 2 upstream of the external heat exchanger 18th are combined so that the total refrigerant mass flow is cooled.

The two valves A3 and A4 can be designed as a combination valve in a kind of multi-way valve and thereby have the full functionality of the individual valves A3 and A4 feature. In further developments, further valves such as A2 and or A5 be merged.

Alternatively, at least a partial mass flow can be downstream of the heating register 26th for example via the connection section 16.4 and the adjustable valve A1 upstream of the internal heat exchanger 20th are introduced into the primary line (branch From 6 ). The valve A1 should be designed as a continuously adjustable valve in this case.

QUOTES INCLUDED IN THE DESCRIPTION

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

Patent literature cited

• DE 102018213232 A1 [0003]
• DE 10029934 A1 [0004]
• EP 1451031 B1 [0004]
• DE 10215587 A1 [0004]

Claims (16)

Post-heating method (500) for operating a refrigeration system (10) with a heat pump function for a motor vehicle, the refrigeration system (10) comprising: a refrigerant compressor (12) with a primary line (14) and a secondary line (16) is connectable or connected; an external heat exchanger (18) which is arranged in the primary line (14); an evaporator (22) which is arranged in the primary line (14); a heating register (26) arranged in the secondary line (16); a primary line valve (A4) arranged between the refrigerant compressor (12) and the external heat exchanger (18); a secondary branch valve (A3) arranged between the refrigerant compressor (12) and the heating register (26); at least one post-heating expansion valve (AE4) which is arranged between the heating register (26) and the external heat exchanger (18) in the secondary line (16); wherein the post-heating process comprises the following steps: Setting the primary branch valve (A4) and the secondary branch valve (A3) in an at least partially open position such that refrigerant conveyed by the refrigerant compressor (12) is conveyed both into the primary branch (14) and into the secondary branch (16). After heating process (500) Claim 1 , wherein when the secondary branch valve (A3) is at least partially open, the post-heating expansion valve (AE4) is at least partially opened. After heating process (500) Claim 1 or 2 With the primary branch valve (A4) (S503) fully open, the secondary branch valve (A3) is gradually opened (S505) in order to cover an emerging or increasing heating requirement (S506). After heating process (500) Claim 3 , the secondary branch valve (A3) remaining set in an open position (S508) when the heating requirement is met (S506, S507). After heating process (500) Claim 3 or 4th , whereby the secondary branch valve (A3) is gradually closed when the heating requirement (S507) or excess heating decreases (S510). After heating process (500) Claim 1 , starting from a state in which the secondary branch valve (A3) is completely open (S509) and the primary branch valve (A4) is at least partially open (S512), the primary branch valve (A4) is gradually closed (S511) to an increasing heating requirement (S506) to cover. Nachheizverfahen (500) after Claim 6 , the primary branch valve (A4) remaining set in an open position when the heating requirement is met. After heating process (500) Claim 6 or 7th , whereby the primary branch valve (A4) is opened step by step when the heating demand or heating surplus decreases. Post-heating process (500) according to one of the preceding claims, wherein the post-heating process is completed (S513; S521) when the primary branch valve (A4) is completely open (S519) and the secondary branch valve (A3) is completely closed (S520), or when the primary branch valve ( A4) is completely closed (S512) and the secondary branch valve (A3) is completely open (S509). Post-heating method (500) according to one of the preceding claims, wherein the partial refrigerant mass flows present in the primary branch (14) and in the secondary branch (16) with the primary branch valve (A4) and secondary branch valve (A3) at least partially open at the same time are brought together at least partially upstream of the external heat exchanger (18) . A refrigeration system (10) with a heat pump function for a motor vehicle, with a refrigerant compressor (12) which can be or is connected to a primary line (14) and a secondary line (16); an external heat exchanger (18) which is arranged in the primary line (14); an evaporator (22) which is arranged in the primary line (14); a heating register (26) arranged in the secondary line (16); a primary line valve (A4) arranged between the refrigerant compressor (12) and the external heat exchanger (18); a secondary branch valve (A3) arranged between the refrigerant compressor (12) and the heating register (26); at least one post-heating expansion valve (AE4) which is arranged between the heating register (26) and the external heat exchanger (18) in the secondary line (16); characterized in that the primary branch valve (A4) and the secondary branch valve (A3) are designed as continuously adjustable valves so that the refrigeration system (10) is set up to be operated with a reheating method (500) according to one of the preceding claims. Refrigeration system (10) Claim 11 , wherein it has a connecting section (16.3; 16.4) designed with an adjustable valve (A1), the end (Ab5) on the secondary flow side being arranged downstream of the heating register (26) and the end (Ab1; Ab6) on the primary flow side being arranged upstream of the evaporator (22) is. Refrigeration system (10) Claim 12 , wherein the primary-flow-side end (Ab6) of the connecting section (16.4) is arranged upstream of an inner heat exchanger (20). Refrigeration system (10) according to one of the Claims 11 until 13th , a check valve (R3) being arranged in the secondary branch (16) downstream of the heating register (26). Refrigeration system (10) Claim 14 , wherein the check valve (R3) is arranged downstream of the post-heating expansion valve (AE4). Motor vehicle with a refrigeration system (10) according to one of the Claims 11 until 15th .

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