WO2020216586A1

WO2020216586A1 - Method for operating a vehicle refrigeration system with combined refrigeration system and heat pump operation

Info

Publication number: WO2020216586A1
Application number: PCT/EP2020/059124
Authority: WO
Inventors: Dirk Schroeder; Christian Rebinger; Helmut Rottenkolber
Original assignee: Audi Ag
Priority date: 2019-04-25
Filing date: 2020-03-31
Publication date: 2020-10-29
Also published as: DE102019205901A1; CN113767021A; CN113767021B; DE102019205901B4

Abstract

The invention relates to a method for operating a refrigeration system (1) for a vehicle comprising a refrigerant circuit (2) which can be operated for refrigeration system and heat pump operation and has at least one branch portion (VZ1, VZ2, VZ3) for conducting the refrigerant either into a first conduit branch to carry out a first operating mode or into a second conduit branch to carry out a second operating mode, wherein - to switch the refrigerant circuit (2) between the first and second operating modes, a first valve member enabling a first refrigerant flow into the first conduit portion and a second valve member enabling a second refrigerant flow into the second conduit portion are provided, the first and second valve members being designed with variably controllable cross-section, and - to switch from the first into the second operating mode, firstly the second valve member is opened up to a predefined target cross-section, and, once the predefined target cross-section of the second valve member has been reached, the first valve member is closed by a reduction of the cross-section.

Description

Method for operating a vehicle refrigeration system with a combined refrigeration system and heat pump operation

DESCRIPTION:

The invention relates to a method for operating a refrigeration system for a vehicle with a refrigerant circuit that can be operated for a refrigeration system and heat pump operation.

There are vehicle air conditioning systems with heat pump functions are known that now have a high complexity due to numerous interconnection options. Different operating modes, such as a refrigeration system operation with one or more evaporators, various reheat operations, an air heat pump operation, a water heat pump operation and a triangular operation as an additional heat pump operation (the refrigerant compressor is the only heat source), have certain basic events on. In addition, there are also mixed and combination operations, for example air and water heat pump operation and at least one de-icing function.

An interconnection change between the different operating modes takes place by activating individual shut-off valves, switchover valves, multi-way valves and / or expansion valves, which are electrically controllable with a variably adjustable cross section. Such valves can be moved between a closed and an open state, but also remain in an intermediate position. With such interconnection changes, there is a risk that the heating and / or cooling capacity will collapse for a short time or that the system operation will have to be interrupted, which means that the system must be restarted in the new configuration. Loss of comfort for vehicle occupants is therefore not excluded.

In the event of such interconnection changes, when the system operation is interrupted, the refrigerant compressor of the refrigerant circuit must be switched off in order to prevent the system from moving "against block". This, too, can lead to a short-term drop in heating and / or cooling capacity, with the consequence of a loss of comfort for the vehicle occupants.

DE10 2016 005 782 A1 describes a method for operating a vehicle air conditioning system with a refrigerant circuit, in which a heat flow is regulated by adjusting a valve cross-section at a minimum compressor speed. By adjusting the cross section on an expansion element, it is achieved that the refrigerant compressor of the Käl temittelkreislaufes does not work in 2-point control mode, but can be operated continuously.

From DE 11 2014 006 077 T5 an air conditioning system for vehicles is known, which can be operated in a heat pump mode. This known air conditioning system comprises several independently electrically adjustable re valves and a refrigerant compressor, the speed of which is limited to a maximum value.

Finally, DE 10 2016 001 096 A1 describes a method for operating a vehicle refrigeration system in which a target air temperature is set by setting a compressor speed of a refrigerant compressor and a cross section of a variable expansion element.

The object of the invention is a method for operating a refrigeration system for a vehicle with a refrigeration system and heat pump Specify operation operable refrigerant circuit with which the refrigeration system can be switched between different operating modes without the above-mentioned disadvantages occurring, at least only to a limited extent.

This object is achieved by a method having the features of patent claim 1.

According to the invention, a method for operating a refrigeration system for a vehicle with a refrigerant circuit that can be operated for a refrigeration system and heat pump operation with at least one branch section for conduction of the refrigerant either in a first line branch for performing a first operating mode or in a second line branch for implementation is provided proposed a second mode of operation in which

- To switch the refrigerant circuit between the first and second operating mode, a first valve element allowing a first refrigerant flow into the first line section and a second valve element enabling a second refrigerant flow into the second line section are provided, the first and second valve elements being variable controllable cross-section are formed, and

- To switch from the first to the second operating mode, first open the second valve member up to a predetermined target cross-section and when the predetermined target cross-section of the second valve member is reached, the first valve member is closed by reducing the cross section.

In this switching strategy between a first and second operating mode, the second valve element, which could cause a blockage, is opened up to a predetermined target cross-section before the first valve element, with which the refrigerant flow is controlled for the first operating mode, is closed. Only when this target cross-section is reached, the first valve member is moved in the completely closed direction. For this purpose, these valve members are electrically adjustable, ie their flow cross-section for the refrigerant can be variably controlled, each intermediate position between 0% cross-sectional opening and 100% cross-sectional opening being adjustable and maintained. As a result, the valves are designed to be lockable in such a way that they do not fall shut or suddenly move.

With such a switchover strategy, the risk is avoided, or at least reduced, that the refrigeration system runs "against the block". In essence, there is also no drop in heating and / or cooling power, so that losses in comfort for the vehicle occupants are excluded, but at least only minimal.

According to an advantageous development of the invention, it is provided that

- By means of a third valve member, the second refrigerant flow can flow through the second line branch, and

- The first valve member is closed and the third valve member is opened with the first valve member cross-section synchronously.

Such a third valve element prevents refrigerant from flowing into the second line branch during the first operating mode.

The first and third valve members are functionally coupled in such a way that they move synchronously in opposite directions, so that, for example, between the first closing valve member and the third opening valve member, the cross-sectional area that can be freely flowed through is always equal to the maximum original cross-sectional area. This can be done at the same time or at different times.

According to a further preferred embodiment of the invention, a fourth valve member prevents refrigerant from flowing through the first line branch. During the switchover from the first to the second operating mode, the first and fourth valve elements are transversely Closed cut synchronously to each other. This can be done simultaneously or offset in time.

Such a fourth valve element prevents refrigerant from flowing into the first line branch during the second operating mode.

Here, the first and fourth valve members are functionally coupled in such a way that they move synchronously in the same direction, that is to say close with synchronous cross-sections. This can be done at the same time or at different times.

Further advantageous embodiments of the method according to the invention are given in claims 4 to 9. Thus, patent claim 4 relates to switching between a refrigeration system operation and a heat pump operation and switching between an air heat pump operation and a water heat pump operation (patent claims 5 to 7). The switchover between a first and second reheat operation relates to claim 8. Claim 9 describes the switchover between a refrigeration system operation and the first reheat operation.

According to a last preferred development of the invention, it is particularly advantageous to set the refrigerant compressor of the refrigerant circuit to a predefined speed value while switching between two operating modes. In this way, the refrigerant compressor should not be subjected to an increase in speed during a switchover from the first to the second operating mode. For this purpose, the control signal for an electric refrigerant compressor is "clamped" to the predefined speed value. For safety reasons, a speed reduction is of course still permissible.

Here, the predefined speed value can either match the speed value that was valid before switching from the first to the second operating mode. numerical value or a speed value calculated from maps or using suitable formulas.

Further advantages, features and details of the invention emerge from the following description of preferred embodiments and with reference to the single FIG. 1, which shows a circuit diagram of a refrigeration system for a vehicle with a refrigerant circuit that can be operated for a refrigeration system and heat pump operation.

The refrigeration system 1 according to FIG. 1 can be operated both in a refrigeration system operation (called AC operation for short) and in a heat pump operation (called HP operation for short), the Fleizbetrieb being carried out by means of a heat pump function and for this purpose in a Fleizzweig 2.2 designed as an air-refrigerant heat exchanger heat exchanger 4 is arranged as a Fleizregister. This heat exchanger 4 is installed together with an evaporator 3 in an air conditioner 1.1, whereby for the conditioning of a cabin supply air flow L routed into a vehicle interior, it is initially routed via the evaporator 3 and then via the heat exchanger 4 and, if necessary, via an electrical fleece element 7 . This Fleizelement 7 is, for example, leads out as a Flochvolt PTC Fleizelement. In addition to the air conditioner 1.1, the refrigeration system 1 has a chiller 9, which is thermally connected to a coolant circuit 9.0 for cooling, for example a floch-volt battery.

The refrigerant circuit 2 consists of:

- the air conditioner 1.1 with an evaporator 3, e.g. a front evaporator and the heat exchanger 4 (also called Fleizregister), the Ver evaporator 3 is arranged in an evaporator branch 3.1 and the heat exchanger 4 in egg nem Fleizregisterzweig 4.1,

- a refrigerant compressor 5,

- an external air-refrigerant heat exchanger 6 designed as a condenser or gas cooler with a heat pump expansion element AE3 assigned to the same in its function as a heat pump evaporator for meat operation, - an internal heat exchanger 11,

- an accumulator 10 on the low pressure side,

- an evaporator expansion element AE2 arranged in the evaporator branch 3.1 and upstream of the evaporator 3,

- A check valve R1 connected downstream of the evaporator branch 3.1, which is fluidly connected to the inlet side of the refrigerant compressor 5 via the accumulator 10 and the low-pressure side section of the inner heat exchanger 11,

- A chiller branch 9.1 with the chiller 9 and a chiller expansion device AE1 upstream of this, the chiller 9 not only cooling, for example, an electrical component of the vehicle but also for realizing a water heat pump function using the waste heat at least one electrical component is used,

- An AC and heat pump branch 2.1 with the outer air-refrigerant heat exchanger 6 and a heat pump expansion element AE3, whereby in air-heat pump operation the AC and heat pump branch 2.1 stream upwards via the heat pump expansion element AE3 with the evaporator branch 3.1 to form a Junction point Ab1 can be fluidly connected and downstream via a shut-off device A2 with the low-pressure inlet of the refrigerant compressor 5 can be fluidly connected, while in AC operation the AC and heat pump branch 2.1 is fluid-connectable upstream via a shut-off device A4 to the high-pressure outlet of the refrigerant compressor 5,

- a heating branch 2.2 with the heat exchanger 4, the heating branch 2.2 being fluidly connectable upstream via a shut-off device A3 to the high pressure outlet of the refrigerant compressor 5 and downstream via a shut-off device A1 with the branch point Ab1 and thus with the evaporator branch 3.1 and the chiller branch 9.1,

- a reheat branch 2.3 with a reheat expansion element AE4 designed as an expansion valve, the reheat branch 2.3 being fluidly connectable downstream to the outer air-refrigerant heat exchanger 6 to form a branch point Ab2 and upstream to the heat exchanger 4,

- A heat pump return branch 2.4 with the shut-off element A2 and a check valve R2, the heat pump return branch 2.4 upstream via the branch point Ab2 with the external air-refrigerant heat exchanger 6 and downstream with the accumulator 10 is fluid-connecting bar, and

- A suction branch 2.5 with a shut-off valve A5, the suction branch 2.5 being fluidly connected downstream via a branch point Ab3 with the shut-off valve A2 and the check valve R2 of the heat pump return branch 2.4.

A plurality of pressure-temperature sensors are provided as sensors in the refrigerant circuit 2 for controlling and regulating the system.

The refrigerant compressor 5 is assigned a first pressure-temperature sensor pT1 at the high-pressure output, a second pressure-temperature sensor pT2 at the output of the accumulator 10, a third pressure-temperature sensor pT3 at the output of the external air-refrigerant heat exchanger 6, and a fourth pressure-temperature sensor pT4 at the output of the heat exchanger 4 and a fifth pressure-temperature sensor pT5 at the output of the chiller 8 on the low-pressure side. Since the respective functions of these pressure-temperature sensors are known to the person skilled in the art, they are not explained in more detail.

The following explains the AC operation and the heating operation of the refrigeration system 1.

With the shut-off organs A3 and A4 arranged in a first branch section VZ1, the refrigerant flow, starting from the high-pressure side of the refrigerant compressor 5, depending on the state of these two shut-off organs A3 and A4, either with the shut-off element A4 open and shut-off element A3 in the AC and heat pump branch 2.1 to carry out an AC operation or flows with the shut-off element A3 open and the shut-off element A4 closed to carry out a heating operation by means of a heat pump function in the heating branch 2.2. In AC operation of the refrigerant circuit 1, the high pressure condensed refrigerant flows from the refrigerant compressor 5 when the shut-off device A4 is open in the outer air-refrigerant heat exchanger 6, the high-pressure section of the inner heat exchanger 11, via the fully open heat pump expansion element AE3 by means of the evaporator expansion element AE2 in the evaporator 3 and / or by means of the chiller expansion element AE1 in the chiller 9. The refrigerant flows from the chiller branch 9.1 via the accumulator 10 and the low-pressure section of the internal heat exchanger 11 back to the refrigerant compressor 5, while the refrigerant flows from the evaporator branch 3.1 via the check valve R1 and then via the accumulator 10 and the Niederdruckab section of the internal heat exchanger 11 can also flow back to the refrigerant compressor 5.

In this AC operation, the heating branch 2.2 is shut off by means of the shut-off device A3. To retrieve refrigerant from the inactive heating branch 2.2, the shut-off device A5 is opened and the refrigerant can flow in the direction of the accumulator 10 via the shut-off device A5 and the check valve R2, while the shut-off device A2 is closed at the same time.

The heating operation of the refrigerant circuit 2 of the refrigeration system 1 will be described below. For this purpose, a heat pump operation is carried out by means of at least one heat source. In the heat pump operation of the refrigerant telkreislaufes 2, the cabin supply air flow L supplied to the vehicle interior is heated by means of the heat exchanger 4 and possibly passed through the heating element 7 before the cabin supply air flow L can flow into the vehicle interior.

In the heating mode of the refrigerant circuit 2, using the chiller 9 to implement a water heat pump or using the external air-refrigerant heat exchanger 6 as a heat pump evaporator for realizing an air-heat pump, the shut-off element A4 of the first branch section VZ1 is closed and that Shut-off device A3 of the first th branch section VZ1 is opened so that hot refrigerant, such as R744, can flow into the heating branch 2.2.

To carry out the water heat pump operation by means of the chiller 9, the refrigerant compressed by the refrigerant compressor 5 flows via the heating branch 2.2 into the heat exchanger 4 to give off heat to the cabin supply air flow L and is then opened via the open shut-off device A1 by means of the chiller expansion device AE1 relaxes in the chiller 9 to absorb waste heat from the electrical and / or electronic components arranged in the coolant circuit 9.0. With this heating function, the expansion organs AE3 and AE4 and the shut-off device A5 are closed. In the water heat pump mode, refrigerant removed from the AC and heat pump branch 2.1 is sucked off via the open shut-off element A2 and fed to the refrigerant compressor 5 via the check valve R2.

The heat exchanger 4 can, in addition to the direct condensation or gas cooling described here, also be designed as a refrigerant-heat sink fluid heat exchanger that indirectly heats the air flow, the heat sink fluid being a water-glycol mixture, for example.

To carry out the air-heat pump operation by means of the external air-refrigerant heat exchanger 6 as a heat pump evaporator, the refrigerant flows from the heat exchanger 4 via the open shut-off element A1 into the AC and heat pump branch 2.1 and is released into the outside air by means of the heat pump expansion element AE3 -Coolant heat exchanger 6 for absorbing heat from the ambient air relaxes and then flows back to the refrigerant compressor 5 via the heat pump return branch 2.4. The expansion elements AE1, AE2 and AE4 remain closed, as does the shut-off element A5.

If a combined operation of water and air heat pumps is implemented, then in addition to the chiller expansion element AE1, the heat pump expansion element AE3 is also actively integrated via a control device and both are controlled accordingly for setting and achieving the target values.

In a reheat mode, the cabin supply air flow L fed into the vehicle interior is first cooled and thus dehumidified by means of the evaporator 3, in order to then use the heat extracted from the cabin supply air flow L and the heat supplied to the refrigerant via the refrigerant compressor 5 Heat exchanger 4 to heat the cabin supply air flow L at least partially again.

Reheat operation of the refrigerant circuit 1 is carried out in different ways depending on the heat balance.

In the event of excess heat in reheat operation, hereinafter referred to as first reheat operation, in addition to the heat output to the cabin supply air flow L of the passenger compartment via the heat exchanger 4, heat is also transferred to the surroundings via the external air-refrigerant heat exchanger 6 Vehicle delivered before the refrigerant flows back to the refrigerant compressor 5 via the evaporator 3. In addition, the refrigerant flows from the heat exchanger 4 into the reheat branch 2.3 when the shut-off element A1 is closed. There, the refrigerant is expanded to a medium pressure in the outer air-refrigerant heat exchanger 6 of the AC and heat pump branch 2.1 by means of the reheat expansion element AE4. The refrigerant then flows from the AC and heat pump branch 2.1 into the evaporator branch 3.1, where it is

Expansion organ AE2 is expanded in the evaporator 3 to low pressure.

Alternatively, when there is sufficient heating power available at the heat exchanger 4, the reheat expansion element AE4 can be opened so far that ideally the same high pressure level is present in the heat exchanger 4 and in the outer air-refrigerant heat exchanger 6. If there is a lack of heat in the refrigerant circuit 2, ie if there is a heating deficit at the heat exchanger 4, the chiller 9 is used as a heat source in addition to the evaporator 3. This reheat operation is called the second reheat operation below.

In this second reheat mode, refrigerant flows through the heating branch 2.2 and thus also the heat exchanger 4 when the shut-off element A3 is open, which then enters both the evaporator 3 of the evaporator branch 3.1 and the chiller 9 of the chiller branch 9.1 when the shut-off element A1 is open is relaxed by means of the associated expansion organs AE1 and AE2. The heat pump expansion element AE3 and the reheat expansion element AE4 are closed during this second reheat operation. The refrigerant flows from the evaporator 3 via the check valve R1, via the accumulator 10 and the internal heat exchanger 11 back to the refrigerant compressor 5. The refrigerant from the chiller 9 flows via the accumulator 10 and the internal heat exchanger 11 as well as back to the refrigerant compressor 5. The heat absorbed in the evaporator 3 and in the chiller 9 is released together with the heat flow entered via the refrigerant compressor 5 via the heat transfer device 4 back to the cabin supply air flow L guided into the vehicle interior. Alternatively, if there is a lack of heat in the refrigerant circuit 2, the air-refrigerant heat exchanger 6 can either be used instead of the chiller 9 as a heat source or connected in parallel to the chiller 9 as an additional heat source. With sufficient heating power in the refrigerant circuit 2, only the Ver evaporator 3 flows through with refrigerant. This reheat operation is called the third re-heat operation. Switching between the operating modes described above takes place by activating the individual shut-off devices, which are designed either as shut-off valves or as expansion valves. Switching valves and / or multi-way valves are also used for this purpose. These shut-off devices are electrically controllable and can be set in any intermediate position between 0% cross-sectional opening and 100% cross-sectional opening and held in such an intermediate position.

In the following, various switching processes between the above-mentioned operating modes are explained by way of example in order to prevent or at least minimize a drop in heating and / or cooling capacity during such a switching process and to avoid restarting the refrigeration system 1. The switchover strategy shown below uses the same terms for changing from one operating mode, hereinafter referred to as the first operating mode, to another operating mode, hereinafter referred to as the second operating mode. With such a change from a first to a second operating mode, a refrigerant flow is deflected in a branch section of the refrigerant circuit 2. Such a branch section, namely a first branch section VZ1, a second branch section VZ2 and a third branch section VZ3, has valve elements with which the refrigerant flow, hereinafter referred to as the first refrigerant flow, from a first line section to carry out the first operating mode in a second Line section is deflected as the second refrigerant flow to carry out the second operating mode. The valve member of the branching section which causes the first refrigerant flow is called the first valve member and the valve member of the branching section which causes the second refrigerant flow is called the second valve member.

Depending on which switching processes between two operating modes are described, the designations for the valve members involved in this switching of the respective branching section are used "First valve element", "second valve element", "third valve element", "fourth valve element" and "nth valve element" are used, where "n" describes the maximum number of switchable valve elements that are present. First, a switchover of the refrigeration system 1 from AC operation as the first operating mode to heat pump operation as the second operating mode is described.

In this switching process, the first branch section VZ1 with the shut-off element A4 as the first valve element, which enables a first refrigerant flow into the AC and heat pump branch 2.1, and the shut-off element A3 as the second valve element, which enables a second refrigerant flow into the heating branch 2.2, involved. Furthermore, the shut-off element A1 is also involved in this switching process as a third valve element.

In addition to the main flow circuit described above, the valve element A5 of the secondary flow must be closed before the change in direction of flow. In AC mode, the first operating mode is the first valve element A4, while the second valve element A3 and the third valve element A1 are closed. In order to enable AC operation, the heat pump expansion element AE3 is of course completely open, so that the refrigerant can be expanded into the evaporator 3 by means of the evaporator expansion element AE2.

The switching process begins with the speed of the refrigerant compressor 5 being kept constant during the switching process at a predefined speed value or at the value of the last speed set.

Simultaneously or subsequently with the "clamping" of the refrigerant compressor 5 to the constant speed value, the second valve element A3 is moved up to a specified target cross section with a defined travel speed. open. When the predetermined target cross-section is reached, the closing process of the first valve member A4 begins by continuously reducing its cross-section to zero. The second valve element A3 is completely opened starting from the specified target cross section. The time lag between reaching the specified target cross-section of the second valve member A3 and the start of the closing process of the first valve member A4 is ultimately dependent on the speed of the controlled valve, which can vary depending on the drive version.

In addition to the time dependency, an opening cross-section-dependent procedure can be selected. When the valve member has reached a certain travel position and thus a corresponding opening cross section, the closing process of the second valve member can be started. Modern valve organs are able to provide exact position feedback, so that a control unit of the refrigeration system 1 is always informed of the current valve position and thus the opening cross-section that can be stored by the characteristic curve. So that the second refrigerant can flow through the heating branch 2.2, the third valve element A1 is opened so that refrigerant is used either to carry out a water heat pump operation in the chiller branch 9.1 and / or to carry out an air heat pump operation in the AC - and heat pump branch 2.1 can flow.

With the closing of the first valve member A4, which is offset in time but timely downstream, with respect to the second valve member A3, the third valve member A1 is opened cross-section synchronously with the closing of the first valve member A4. Thus, the first valve element A4 and the third valve element A1 are moved synchronously in opposite directions so that, in a selectable variant, the sum of the cross-sections of the closing first valve element A4 and the opening third valve element A1 corresponds to the original maximum cross-sectional area of the closing first valve element A4. The Closing the first valve member A4 and the opening of the third valve member A1 begin at the same time.

It is advantageous if the heat pump expansion element AE3 is closed synchronously with the closing of the valve member A4 and the opening of the valve member A1 or is kept at a small opening cross-section in the event that an air heat pump operation follows. The valve element A2 must also be opened independently of air or water heat pump operation. Since there is a risk of a short circuit of the refrigerant flow from the outlet to the inlet of the refrigerant compressor 5 via the valve member A2 before the valve member A4 closes completely, the valve member A2 is preferably closed immediately after the valve member A4 has been closed, alternatively based on the cross-sectional area shortly before complete closure to open. The switching process from AC operation as the first operating mode to heat pump operation as the second operating mode is ended when the first valve element A4 is completely closed and the third valve element A1 and valve element A2 are completely open. A heat pump operation can thus be carried out by means of the chiller 9 and / or by means of the air-refrigerant heat exchanger 6 as a heat pump evaporator.

The first branching section VZ1 with the shut-off element A3 as the first valve element, which enables a first refrigerant flow into the heating branch 2.2, and the shut-off element A4 as a reversed switching process, i.e. from a heat pump operation as the first operating mode to the AC operation as the second operating mode, are the first branch section VZ1 second valve element, which enables a second refrigerant flow in the AC and heat pump branch 2.1, involved, Furthermore, the valve organ A1 as a fourth valve element and the valve element A2 and the heat pump expansion element AE3 are also involved in this switching process.

In the heat pump mode as the first operating mode, the first Ventilor gan A3 and the fourth valve organ A1 are open, while the second Ventilor gan A4 is closed. To enable heat pump operation, either refrigerant is expanded into the AC and heat pump branch 2.1 by means of the heat pump expansion element AE3 and / or into the chiller branch 9.1 by means of the chiller expansion element AE1. This switching process also begins with the speed of the refrigerant compressor 5 being kept constant at a predefined speed value or at the value of the last set speed during the switching process. Simultaneously or subsequently with the "clamping" of the refrigerant compressor 5 to a constant speed value, the second valve element A4 is opened up to a specified target cross section with a defined travel speed and the closing of the valve element A2 is coupled directly or in advance to this travel process. When the specified target cross-section is reached, the closing process of the first valve organ A3 begins, in that its cross-section is continuously reduced to the value zero. The second valve member A4 is fully opened starting from the specified target cross-section. The time delay between reaching the predetermined target cross-section of the second valve member A4 and the beginning of the closing process of the first valve member A3 is ultimately dependent on the travel speed of the controlled valve member, which can vary depending on the drive design.

Ultimately, the opening cross-sections coupled to the travel path can be evaluated again using valve characteristics and position detection, and the travel process can start depending on the values achieved.

In order to prevent refrigerant from flowing back from the AC heat pump branch 2.1 into the heating branch 2.2 during AC operation, the shut-off element A1 must of course be closed as the fourth valve element. The same applies to valve element A2 in order to avoid a short circuit with the low pressure side in AC operation. With the subsequent closing of the first valve element A3 with a time offset relative to the second valve element A4, the fourth valve element A1 is closed cross-section-synchronously with the first valve element A3. The first valve element A3 and the fourth valve element A1 are thus moved synchronously in the same direction into their closed state. The closing of the first valve organ A3 and the closing of the fourth valve organ A1 ideally begin simultaneously. Alternatively, a time offset can also be implemented. The closing process of the first valve member A3 begins here before the fourth valve member A1 follows.

The switchover process from heat pump operation as the first operating mode to AC operation as the second operating mode is ended when the first valve element A3 and the fourth valve element A1, and possibly the valve element A2, are completely closed. AC operation can thus be carried out by means of the evaporator 3.

The process of switching from an air heat pump operation as the first operating mode to a water heat pump operation as the second operating mode will now be described.

In an air heat pump operation, the heating branch 2.2 is connected to the high pressure outlet of the refrigerant compressor 5 on the upstream side when the shut-off element A3 is open and downstream to the AC and heat pump branch 2.1 via the open shut-off element A1 by means of the heat pump expansion element AE3, and at the same time the shut-off element A2 of the heat pump return branch 2.4 is open. When the water heat pump is operated, the heating branch 2.2 is connected to the chiller branch 9.1. In these heat pump operations, the evaporator expansion element AE2 and the reheat expansion element AE4 are closed.

A second branch section VZ2 with the heat pump expansion element AE3 as the first valve element, which generates a first refrigerant flow into the AC and heat pump branch 2.1, is part of this switching process. possible, and the chiller expansion element AE1 as a second valve element, which enables a second refrigerant flow into the chiller branch 9.1, involved. In the air / heat pump mode as the first operating mode, the first valve element AE3 is opened with a corresponding cross section to fulfill its expansion function, while the second valve element AE1 is closed. In order to enable water heat pump operation, the refrigerant in the chiller branch 9.1 is expanded by means of the chiller expansion element as the second valve element AE 1.

The switching process to water heat pump operation as the second operating mode also begins with the speed of the refrigerant compressor 5 being kept constant during the switching process at a predefined speed value or at the value of the last set speed.

Simultaneously or subsequently with the “clamping” of the refrigerant compressor 5 to a constant speed value, the second valve element AE1 is opened up to a predetermined target cross section with a defined travel speed. When the predetermined target cross-section is reached, the closing process of the first valve member AE3 begins, in that its cross-section is continuously reduced to the value zero. The second valve element AE1 is opened on the basis of the specified target cross-section to a target cross-section in order to fill its expansion function. The time lag between reaching the specified target cross-section of the second valve member AE1 and the start of the closing process of the first valve member AE3 is ultimately dependent on the travel speed of the valve being controlled, which can vary depending on the drive version.

The shut-off element A2 of the heat pump return branch 2.4 remains open due to a suction of refrigerant from the AC and heat pump branch 2.1, while all other valve elements last before the switchover Maintain position in the process. The switching process is now complete.

The reverse switchover process, that is to say the switchover from the water heat pump process as the first operating mode to the air heat pump process as the second operating mode, will now be described.

The second branching section VZ2 with the chiller expansion element AE1 as the first valve element, which enables a first refrigerant flow into the chiller branch 9.1, and the heat pump expansion element AE3 as the second valve element, which feeds a second refrigerant flow into the AC and Heat pump second 2.1 enabled, involved. The switching process to the air / heat pump process as the second operating mode also begins with the speed of the refrigerant compressor 5 being kept constant during the switching process at a predefined speed value or at the value of the last set speed.

Simultaneously or subsequently with the “clamping” of the refrigerant compressor 5 to a target speed value, the second valve element AE3 is opened up to a predetermined target cross section with a defined speed of movement. When the predetermined target cross section is reached, the closing process of the first valve member AE1 begins, in that its cross section is continuously reduced to the value zero. The second valve element AE3 is opened starting from the specified target cross-section to the cross-section (target cross-section) required to carry out the expansion function. The time lag between reaching the predetermined target cross-section of the second valve member AE3 and the start of the closing process of the first valve member AE1 is ultimately dependent on the travel speed of the controlled valve, which can vary depending on the drive version. Next, a switchover of the refrigeration system 1 from AC operation as the first operating mode to the first reheat operation as the second operating mode will be described. In this switching process, the first branch section VZ1 with the shut-off element A4 as the first valve element, which enables a first refrigerant flow into the AC and heat pump branch 2.1, and the shut-off element A3 as the second valve element, which enables a second refrigerant flow into the heating branch 2.2, involved, In addition, the reheat expansion element AE4 is also involved as a third valve element in this switching process.

In AC operation as the first operating mode, the first valve element A4 is open, while the second valve element A3 and the third valve element AE4 are closed. In order to enable AC operation, the heat pump expansion element AE3 is of course completely open, so that the refrigerant can be expanded into the evaporator 3 by means of the evaporator expansion element AE2. The switching process begins with the speed of the refrigerant compressor 5 being kept constant at a predefined speed value or at the value of the last speed set during the switching process. Simultaneously or subsequently with the “clamping” of the refrigerant compressor 5 to a target speed value, the second valve element A3 is opened up to a predetermined target cross section with a defined travel speed. When the predetermined target cross-section is reached, the closing process of the first valve member A4 begins, in that its cross-section is continuously reduced to the value zero. The second valve member A3 is opened from the predetermined target cross section to a maximum cross section or completely. The time lag between reaching the predetermined target cross-section of the second valve member A3 and the beginning of the closing process of the first valve member A4 is ultimately depends on the travel speed of the controlled valve, which can vary depending on the drive version.

So that the second refrigerant flow can flow through the heating branch 2.2, the third valve element AE4 is opened to carry out a corresponding expansion function, so that refrigerant can flow into the reheat branch 2.3 to carry out the first reheat operation. When the first valve element A4 closes with a time delay compared to the second valve element A3, the third valve element AE4 is opened cross-section-synchronously with the first valve element A4. The first valve element A4 and the third valve element AE4 are synchronously moved in opposite directions so that the sum of the cross-sections of the closing first valve element A4 and the opening third valve element AE4 corresponds to the original maximum cross-sectional area of the closing first valve element A4. The closing of the first valve member A4 and the opening of the third valve member AE4 begin at the same time. The switching process is preceded by the closing of the valve member A5, which in AC operation causes the suction of refrigerant from the segmented heating branch 2.2 in order to prevent a short circuit between the heating branch 2.2 and the suction side of the refrigerant compressor 5. The switching process from AC operation as the first operating mode to the first reheat operation as the second operating mode is ended when the first valve element A4 is completely closed and the third valve element AE4 is open to a target cross-section that can be up to 100%. The first reheat operation can thus be carried out by means of the heat exchanger 4, the outer air-refrigerant heat exchanger 6 and the evaporator 3.

In the reverse switching process, i.e. switching from the first reheat mode as the first operating mode to the AC mode as the second Operating mode, the first branch section VZ1 with the shut-off organ A3 as the first valve organ, which enables a first refrigerant flow into the heating branch 2.2, and the shut-off organ A4 as a second valve organ, which enables a second refrigerant flow in the AC and heat pump branch 2.1, involved Furthermore, the reheat expansion element AE4 is also involved as a fourth valve element in this switching process.

In the first reheat mode as the first operating mode, the first valve element A3 and the fourth valve element AE4 are open, while the second valve element A4 is closed. To enable AC operation, the second valve element A4 is open, so that refrigerant can flow into the AC and heat pump penzweig 2.1 and when the heat pump expansion element AE3 is open into the evaporator branch 3.1. This switching process from the first reheat mode as the first operating mode to the AC mode as the second operating mode also begins with the speed of the refrigerant compressor 5 being kept constant during the switching process at a predefined speed value or at the value of the last set speed.

Simultaneously or subsequently with the “clamping” of the refrigerant compressor 5 to a target speed value, the second valve element A4 is opened up to a predetermined target cross section with a defined travel speed. When the specified target cross-section is reached, the closing process of the first valve member A3 begins by continuously reducing its cross-section to zero. The second valve element A4 is completely opened starting from the specified target cross section. The time lag between reaching the predetermined target cross section of the second valve member A4 and the beginning of the closing process of the first valve member A3 is ultimately dependent on the speed of the valve being controlled, which can vary depending on the drive version. In order for refrigerant to flow from the reheat branch 2.3 into the heating branch 2.2 in AC operation, the reheat expansion element AE4 must of course be closed as the fourth valve element. With the subsequent closing of the first valve member A3 with a time delay compared to the opening of the second valve member A4, the fourth valve member AE4 is closed with the first valve member A3 in a cross-section synchronous manner. The first valve element A3 and the fourth valve element AE4 are thus moved synchronously in the same direction into their closed state. The closing of the first valve member A3 and the closing of the fourth valve member AE4 begin simultaneously. Alternatively, the closing of the re-expansion element AE4 as the fourth valve element can also be coupled or preceded by the opening process of the second valve element A4 in order to avoid an undefined refrigerant flow. Due to the state of the aggregate and the density of the refrigerant at the fourth valve element AE4, even the upstream control and thus the start of the closing process is an alternative procedure.

The switchover process from the first reheat mode as the first operating mode to the AC mode as the second operating mode is ended when the first valve element A3 and the fourth valve element AE4 are completely closed. AC operation can thus be carried out by means of the evaporator 3. This conclusion is followed by the opening of the valve member A5 and since the beginning of the refrigerant return from the segmented heat pump branch 2.2.

As the last example of a switchover process, a switchover of the refrigeration plant 1 from the first reheat mode as the first operating mode to the second reheat mode as the second operating mode is described.

A third branch section VZ3 with the reheat expansion element AE4 as the first valve element, which enables a first refrigerant flow into the reheat branch 2.3, and the shut-off element A1 as the second valve element, which has a second refrigerant telstrom in the evaporator branch 3.1 and the chiller branch 9.1 enables involved. Furthermore, the heat pump expansion element AE3 is also involved as a fourth valve element in this switching process. In the first reheat mode as the first operating mode, the first valve element AE4 is at least partially open, while the second valve element A1 is closed. In order to enable a second reheat operation, the re-heat expansion device AE4 is completely closed, while the shut-off device A1 is fully open and the chiller expansion device AE1 as well as the evaporator expansion device AE2 cross-section to a predetermined target to carry out the Expansion functions are open.

The changeover process begins with the speed of the refrigerant compressor 5 being kept constant during the changeover process at a predefined speed value or at the value of the last speed set.

Simultaneously or subsequently with the “clamping” of the refrigerant compressor 5 to a target speed value, the second valve element A1 is opened up to a predetermined target cross section with a defined travel speed. When the specified target cross-section is reached, the closing process of the first valve member AE4 begins, in that its cross-section is continuously reduced to the value zero. The second valve element A1 is opened, starting from the specified target cross section, to a maximum of a nominal cross section or completely. The time lag between reaching the specified target cross-section of the second valve member A1 and the beginning of the closing process of the first valve member AE4 is ultimately dependent on the travel speed of the valve being controlled, which can vary depending on the drive version.

The fourth valve element AE3 is open so that the first refrigerant flow can flow through the reheat branch 2.3 and then the AC and heat pump branch 2.1. With the subsequent closing of the first valve element AE4 with a time delay compared to the second valve element A1, the third valve element AE3 is also closed with the first valve element AE4 in a cross-section synchronous manner. The closing of the first valve element AE4 and the closing of the fourth valve element AE3 begin at the same point in time. Finally, the valve member A2 is opened to enable the refrigerant to be extracted from the inactive AC and heat pump branch 2.1.

The switchover process from the first reheat mode as the first operating mode to the second reheat mode as the second operating mode is ended when the first valve element AE4 and the fourth valve element AE3 are completely closed. The second reheat operation can thus be carried out by means of the evaporator 3 and the chiller 9. In the reverse switchover process, i.e. the switchover from the second reheat mode as the first operating mode to the first reheat mode as the second operating mode, the third branch section VZ3 with the shut-off element A1 as the first valve element, which telstrom a first refrigerant into the evaporator branch 3.1 and the chiller branch 9.1 enables, and the reheat expansion element AE4 as a second valve element, which enables a second refrigerant flow into the reheat branch 2.3 involved.

In the second reheat mode, the first operating mode, the first Ventilor gan A1 are open, while the second valve element AE4 and the heat pump expansion element AE3 are closed. Furthermore, in this second reheat mode, the chiller expansion element AE1 and the evaporator expansion element AE2 are set to a setpoint cross-section for carrying out the expansion functions. In the first reheat mode as the second operating mode, the first valve element AE4 and the heat pump expansion element AE3 are opened as the third valve element, while the second valve element A1 is closed.

This is the switching process from the second reheat mode as the first operating mode to the first reheat mode as the second operating mode Closing of the valve element A2 upstream in order to prevent a direct flow of refrigerant to the inlet of the refrigerant compressor when the AC and heat pump branch 2.1 is actively flowing before the speed of the refrigerant compressor 5 is started, the speed of the refrigerant compressor 5 during the switching process to a target speed value or to the value of the last set Set the speed.

Simultaneously or subsequently with the “clamping” of the refrigerant compressor 5 to the target speed value, the second valve element AE4 is opened up to a predetermined target cross-section at a defined travel speed. When the predetermined target cross-section is reached, the closing process of the first valve member A1 begins, in that its cross-section is continuously reduced to zero. The second valve element AE4 is opened, starting from the specified target cross-section, to a target cross-section to carry out the expansion function. The time lag between reaching the predetermined target cross-section of the second valve member AE4 and the start of the closing process of the first valve member A1 is ultimately dependent on the speed of the controlled valve, which can vary depending on the drive version.

In order for refrigerant to flow into the AC and heat pump branch 2.1 in the first reheat operation, the heat pump expansion element AE3 must of course be opened as the third valve element. With the subsequent closing of the first valve element A1 with a time delay compared to the second valve element AE4, the third valve element AE3 is opened cross-section-synchronously with the second valve element AE4. So who the first valve member A1 and the third valve member AE3 move synchronously ge in opposite directions. The closing of the first valve element A1 and the opening of the fourth valve element AE3 begin simultaneously.

The switching process from the second reheat mode as the first operating mode to the first reheat mode as the second operating mode is ended when the first valve element A1 is completely closed and the third at the same time Valve element AE3 are fully open. The first reheat operation can thus be carried out by means of the evaporator 3 and the external air-refrigerant heat exchanger 6. In the above-described embodiments, with the start of a switching process, the refrigerant compressor 5 is kept constant at a defined speed value until the end of the switching process. This defined speed value can correspond to the speed value set before the switchover or to a predefined speed value which is calculated from characteristic curves or tables stored in a control unit or using suitable formulas.

Of course, further switching processes of the refrigeration system 1 between two operating modes are possible, the basic procedure corresponding to the switching processes described above.

In this case, to switch from a first operating mode to a second operating mode, a line branch responsible for this is released by means of a valve element, this valve element being opened with a time delay before the valve element which enables the first operating mode is closed.

If a further valve element is required for flow through the line branch that enables the second operating mode, this valve element is opened with the closing of the valve element that enables the first operating mode with cross-section synchronism.

If another valve member is required to prevent the flow of refrigerant through the branch enabling the first operating mode, this further valve member is closed with the valve member that enables the first operating mode to be closed in a cross-section synchronous manner.

As a rule, in contrast to shut-off devices, expansion organs have a different characteristic curve, ie with identical control signals the result is animals with different cross-sectional openings. In the ideal case, however, all of the valve elements mentioned have an approximately identical maximum opening cross-section, which ultimately results in low flow losses in shut-off elements and significantly simplifies serviceability (assembly and disassembly) of the overall system for expansion elements.

Clamping the speed of the compressor 5 to the set speed is always overlaid by the safety function of monitoring the permissible high pressure and the hot gas temperature.

REFERENCE MARK

1 refrigeration system

1.1 Air conditioner

2 Refrigerant circuit of the refrigeration system 1

2.1 AC and heat pump branch of the refrigerant circuit 2

2.2 heating branch

2.3 Reheat branch

2.4 Heat pump return branch

2.5 extraction branch

3 evaporators

3.1 Evaporator branch

4 heat exchangers, heating registers

4.1 Heating register branch

5 refrigerant compressors

6 external air-refrigerant heat exchanger

7 electric heating element

9 chillers

9.0 Coolant circuit of the chiller 8

9.1 Chiller branch

10 accumulator

11 internal heat exchanger

A1 shut-off device

A2 shut-off device

A3 shut-off device A4 shut-off device

A5 shut-off device

Ab1 branch point

Ab2 branch point

Ab3 branch point

AE1 chiller expansion device

AE2 evaporator expansion element AE3 heat pump expansion element

AE4 reheat expansion device

L Cabin supply air flow pT1 first pressure-temperature sensor pT2 second pressure-temperature sensor pT3 third pressure-temperature sensor pT4 fourth pressure-temperature sensor pT5 fifth pressure-temperature sensor

R1 check valve

R2 check valve

VZ1 first branch section VZ2 second branch section

VZ3 third branch section

Claims

PATENT CLAIMS:

1. A method for operating a refrigeration system (1) for a vehicle with a refrigerant circuit (2) that can be operated for refrigeration system and heat pump operation and has at least one branching section

(VZ1, VZ2, VZ3) for the conduction of the refrigerant either in a first line branch for implementing a first operating mode or in a second line branch for implementing a second operating mode, wherein

- To switch the refrigerant circuit (2) between the first and second operating mode, a first valve member enabling a first refrigerant flow in the first line section and a second refrigerant flow enabling egg NEN second refrigerant flow in the second line section is provided, the first and second valve members being variable controllable cross-section are formed, and

- To switch from the first to the second operating mode to the next, the second valve member is opened up to a predetermined target cross-section and, when the predetermined target cross-section of the second valve member is reached, the first valve member through a

Reduction of the cross section is closed.

2. The method of claim 1, wherein

- By means of a third valve element, the second refrigerant flow can flow through the second line branch, and

- The first valve member is closed and the third valve member is opened with the first valve member in cross-section synchronism.

3. The method according to claim 1 or 2, wherein by means of a fourth

Valve element prevents refrigerant from flowing through the first branch line, and

- The first and fourth valve members are closed cross-section synchronously.

4. The method according to any one of the preceding claims, wherein

- By means of an AC and heat pump branch (2.1) as the first or second branch of a first branch section, a refrigeration system operation is carried out as the first or second operating mode by applying the heat of at least one evaporator (3) arranged in an evaporator branch (3.1) to an external air -Coolant heat exchanger (6) of the AC and heat pump branch (2.1) is transferred,

- By means of a heating branch (2.2) as the second or first line branch, a heat pump operation is carried out as a second or first operating mode by the heat from at least one heat source (5, 6, 9) by means of a heat exchanger (4) of the heating branch (2.2) on egg NEN cabins -Supply air flow (L) is transmitted,

- By means of the first branch section, the first and second line branches can be connected upstream to a refrigerant compressor (5), the AC and heat pump branch (2.1) via a first or second valve element (A4) of the first branch section and the heating branch (2.2) Via a second or first valve element (A3) of the first branch section with the refrigerant compressor

(5) is connected,

- the AC heat pump branch (2.1) is connected to an evaporator branch (3.1) to operate the refrigeration system, and

- A third or fourth valve element (A1) causes refrigerant to flow through or not to flow through the heating branch (2.2).

5. The method according to claim 4, in which to carry out an air heat pump operation, the refrigerant by means of a heat pump expansion element (AE3) of the AC and heat pump branch (2.1) is expanded into the external air-refrigerant heat exchanger (6) used as a heat pump evaporator.

6. The method according to claim 4 or 5, in which, in order to carry out a water heat pump operation, the refrigerant is expanded into the chiller (9) by means of a chiller expansion element (AE1) of a chiller (9) having a chiller (9) becomes.

7. The method according to any one of claims 4 to 6, wherein

- a second branch section (VZ2) is connected to the heating branch (2.2) to operate an air or water heat pump,

- To carry out an air-heat pump operation as the first or second operating mode, refrigerant is passed from the heating branch (2.2) into the AC and heat pump branch (2.1) as the first or second branch by means of a first or second valve member designed as a heat pump expansion member (AE3) , and

- To carry out a water heat pump operation as the second or first operating mode, refrigerant is passed from the heating branch (2.2) into the chiller branch (3.1) as a second or first line branch by means of a second or first valve member designed as a chiller expansion member (AE1).

8. The method according to any one of claims 1 to 3, wherein

- By means of an AC and heat pump branch (2.1) that can be connected to the high-pressure outlet of a refrigerant compressor (5), a refrigeration system is carried out by transferring the heat to at least one evaporator (3) arranged in an evaporator branch (3.1) to an external air-refrigerant heat exchanger ( 6) of the AC and heat pump branch (2.1) is transferred,

- By means of a heating branch (2.2) that can be connected to the high pressure outlet of the refrigerant compressor (5), either a first reheat operation is carried out if the heating branch (2.2) is connected to a reheat

Branch (2.3) is connected and a second reheat operation is carried out if the heating branch (2.2) is connected to the evaporator branch (3.1), - By means of a third branch section (VZ3) the heating branch

(2.2) is either connected to a reheat branch (2.3) as the first or second line branch for performing the first reheat operation as a first or second operating mode or to the evaporator branch (3.1) and / or a chiller (9) Chiller branch

(9.1) is connected as a second or first line branch for performing the second reheat operation as a second or first operating mode, with the AC and heat pump branch (2.1) carrying refrigerant from the reheat branch (2.3) in the first reheat operation - is flowing,

- The heating branch (2.2) with the reheat branch by means of a first or second valve member (AE4, A1) of the third branching section

(2.3) is connected,

- By means of a second or first valve member (A1, AE4) of the third branch section (VZ3), the heating branch (2.2) is connected to the evaporator branch (3.1) and / or the chiller branch (9.1), and

- By means of a fourth or third valve member (AE3) of the third branching section (VZ3), a non-flow or a flow of refrigerant through the AC and heat pump branch (2.1) is effected.

9. The method according to any one of claims 1 to 3, wherein

- By means of an AC and heat pump branch (2.1) as the first or second line branch, a refrigeration system operation as the first or second

Operating mode is carried out in that the heat of at least one evaporator (3) arranged in an evaporator branch (3.1) is transferred to an external air-refrigerant heat exchanger (6) of the AC and heat pump branch (2.1),

- A first reheat operation is carried out as a second or first operating mode by means of a heating branch (2.2) and a reheat branch (2.3) connected to the same,

- By means of a first branch section, the first and second line branches are connected upstream to a refrigerant compressor (5) is linked by connecting the AC and heat pump branch (2.1) to the refrigerant compressor (5) via a first or second valve element (A4) of the first branch section and the heating branch (2.2) via a second or first valve element (A3) of the first branch section will, and

- A third or fourth valve element (AE4) causes refrigerant to flow through or not flow through from the heating branch (2.2) into the reheat branch (2.3).

10. The method according to any one of the preceding claims, in which, to switch the refrigerant circuit (2) between the first and second operating mode, a refrigerant compressor (5) of the refrigerant circuit (2) is set to a predefined speed value.