Flexible compression device and refrigerant circulation circuit having

Abstract

The invention relates to a compression device comprising a plurality of single-flow compressors or a multi-flow compressor having a plurality of delivery flow channels, the delivery flow channels or the single-flow compressors being configured such that they can be operated in a parallel connection in order to compress a refrigerant from a low pressure to a higher pressure, and the delivery flow channels or the single-flow compressors being configured such that they can be operated in a parallel connection in order to compress the refrigerant from a lower pressure to a higher pressure. Wherein one or more of the delivery flow channel or the uniflow compressor is / are switchably configured such that it can operate in a connected setting to compress the refrigerant of the first sub-flow from a medium pressure between a low pressure and a higher pressure to a higher pressure, wherein the remaining delivery channels or the single-flow compressors can be operated simultaneously in order to compress the refrigerant of the second sub-flow from a low pressure to a higher pressure, and the compression device has at least one switching device with one or more change-over valves, which is provided for switching one or more switchable delivery channels or single-flow compressors. The invention also relates to a refrigerant circuit having a heat economizer and such a compression device, and to a method therefor.

Description

Field of the Invention

[0001] The present invention relates to a compression device. The compression device includes a plurality of single-flow compressors or a multi-flow compressor having a plurality of delivery channels, wherein the delivery channels or the single-flow compressors are configured such that the delivery channels or the single-flow compressors can operate in parallel connection to compress a refrigerant from a low pressure to a higher pressure. Such a compression device is used, in particular, in a refrigeration installation, an air-conditioning installation or a heat pump in a refrigerant circuit according to the invention for compressing the refrigerant. In addition to at least one compression device, the refrigerant circuit includes, in a circuit-connected manner by means of refrigerant pipes, at least one heat exchanger that can operate as a gas cooler / condenser, at least one expansion mechanism, a recuperator and at least one heat exchanger that can operate as an evaporator.

[0002] Heat is extracted from the hot refrigerant compressed in the compression device during operation in at least one gas cooler / condenser and then the pressure is reduced in at least one expansion mechanism, wherein the refrigerant is cooled. After flowing through at least one evaporator, especially during normal operation, the evaporated refrigerant finally returns to the compression device for recompression.

[0003] Furthermore, the present invention relates to a method for operating such a refrigerant circuit.

[0004] By means of the recuperator, the coefficient of performance of the cycle process can be increased according to the operating conditions. Here, in a secondary branch in the refrigerant circuit, the refrigerant previously compressed in the compression device is decompressed to an intermediate pressure, wherein the refrigerant is cooled in order to extract heat from the hotter compressed refrigerant in the recuperator for increasing the coefficient of performance of the cycle process. The greater the temperature difference between the heat sink at the condenser / gas cooler and the heat source at the evaporator, the greater the improvement of the coefficient of performance by the recuperator. However, when the temperature difference is too low, the available heat transfer surface of the recuperator is too small for the economic operation of the recuperator.

[0005] There are embodiments of the refrigerant circuit in which the refrigerant operates supercritically on the high-pressure side, such as, for example, by using CO2 as the refrigerant, and there are other embodiments in which the refrigerant operates subcritically on the high-pressure side, such as, for example, by using R1234yf as the refrigerant. Background Art

[0006] Compression devices are known that have a plurality of single-flow compressors connected in parallel or a plurality of delivery flow channels of a multi-flow compressor connected in parallel. US2009 / 0175748A1 discloses a compression device having a plurality of compression stages, in which two compressor subunits are connected in parallel, but the compression of the refrigerant in the two compressor subunits has different pressure differences. In the refrigerant circuit disclosed in US2009 / 0175748A1, there are one or more secondary branches for one or more economizers, where the respective suction inlets are associated with the respective delivery flow channels of a part of the refrigerant flow of the respective secondary or main branch fixedly used for the refrigerant, which results in a loss of flexibility when the compression device operates in the refrigerant circuit.

[0007] In DE10354719 A1, a delivery device is disclosed, for example, as a compressor for a compression medium, in which two delivery units can be switched to be connected in series as a multi-stage or in parallel as a multi-flow, that is, configured as two delivery flow channels. These two connection possibilities disadvantageously have a significant difference in terms of the size of the volume flow to be compressed.

[0008] In US2009 / 0320506A1, a refrigerant circuit is shown having a secondary branch with an economizer that can be shut off for refrigerant passage, where, however, the parallel connection of the delivery flow channels is not disclosed as a compression device, but only a two-stage arrangement with an additional suction inlet for a part of the refrigerant in the secondary branch having a medium pressure downstream of the economizer is disclosed.

[0009] A refrigerant cycle circuit having a regenerator and a two-stage compression device is disclosed in CN108759157 A and US2017 / 0159977 A1 respectively, in which a plurality of compressors can operate in a parallel-connected manner not only in the low-pressure stage but also in the high-pressure stage. Here, the compressors in the low-pressure stage compress the refrigerant from low pressure to medium pressure in a parallel-connected manner, and the compressors in the high-pressure stage compress the refrigerant from medium pressure to a higher pressure in a parallel-connected manner. Providing a plurality of compressors for both the low-pressure stage and the high-pressure stage respectively in the corresponding compression device means increased consumption of materials and space. In CN108759157 A, the pressure differences of the parallel-connected compressors in the first stage are always equal. The flexibility of the compression device disclosed in CN108759157 A is thus limited. In US2017 / 0159977 A1, in the high-pressure stage of the compression device, the parallel-connected compressors can be switched so that compression can be carried out with a pressure difference different from that in the remaining parallel-connected compressors in the high-pressure stage by means of the compressors, but the refrigerant can only be compressed from the medium pressure of the refrigerant in the sub-branch extending through the medium-pressure side of the regenerator by means of the switchable compressor. Compression starting from a lower pressure in the high-pressure stage can only be carried out in the remaining parallel-connected compressors in the high-pressure stage. This limits flexibility. DE69722146 T2 discloses a refrigerant cycle circuit having a regenerator and a compression device with power regulation. Here, two accessible parallel low-pressure stages and a common high-pressure stage are provided in the compression device. Therefore, there are two compression stages in the compression device, whereby the compression device is quite complex and costly to control. DE102005009173 A1 discloses a refrigeration facility, which includes a refrigerant cycle circuit having at least two parallel compressors, each of the compressors having an additional compressor stage, and the compressors can be selectively used to compress the refrigerant from the main mass flow or compress the refrigerant from the additional mass flow, and the operating mode is switched by means of a controllable switching valve controlled by a control device. Thereby, there are two compression stages in the compressors, whereby the compressors are quite complex, and the switching of the operating mode by means of the controllable switching valve needs to be actively controlled. DE112017005948 T5 discloses a refrigerant cycle circuit that does not have a regenerator and has a compression device including at least two parallel-connected compressors. Here, in the heat pump operation by means of a controllable switching valve, each compressor can be switched between compressing the refrigerant from a low-pressure level to a high-pressure level or from a medium-pressure level to a high-pressure level. For this purpose, active control of the switching valve is required. In the refrigerator disclosed in DE102014113167 A1, only one of the two parallel compressors in the compression device can be actively switched between compressing the refrigerant from a low-pressure level to a high-pressure level or from a medium-pressure level to a high-pressure level by means of a control unit by means of a switchable three-way switching valve.Here, a switch is made between operation with or without a regenerator.

[0010] Accordingly, the problem underlying the present invention is that the switching device for switching the operating mode of hitherto known compression devices having a plurality of single-flow compressors or multi-flow compressors is in need of improvement. Moreover, the saving of space, material and / or components to be controlled of such hitherto known compression devices is in need of improvement. Thus, the object is to provide an improved compression device having a plurality of single-flow compressors or a multi-flow compressor.

[0011] A corresponding object relates to a refrigerant circuit having a regenerator and such a compression device.

[0012] Furthermore, another object is to provide a method for operating a refrigerant circuit of a switching device for switching between operation with or without a regenerator in a compression device. Summary of the Invention

[0013] The problem underlying the present invention is achieved by the features detailed in the description. The problem is solved by a compression device comprising a plurality of single-flow compressors or a multi-flow compressor having a plurality of delivery channels, wherein the delivery channels or the single-flow compressors are configured such that the delivery channels or the single-flow compressors can be operated in parallel connection to compress a refrigerant from a low pressure to a higher pressure, and wherein one or more of the plurality of delivery channels or single-flow compressors are switchably configured such that they can be operated in a switching setting to compress a first sub-stream of the refrigerant from a medium pressure between the low pressure and the higher pressure to the higher pressure, wherein simultaneously, the remaining delivery channels or single-flow compressors of the plurality of delivery channels or single-flow compressors can be operated to compress a second sub-stream of the refrigerant from the low pressure to the higher pressure, and the compression device has at least one switching device, which is configured such that it comprises one or more conversion valves and is designed for switching the switchable one or more delivery channels or single-flow compressors.

[0014] The compression device is a delivery device designed for compressing a medium. The delivery channels are, for example, the delivery units of a multi-flow compressor having a plurality of delivery units. A conversion valve typically has two inlets. In such a conversion valve, the line is automatically regulated to the passage of the medium, such as in the present case the refrigerant, from one inlet or the other inlet, depending on the respective pressure at the inlet.

[0015] The switching device includes a conversion valve, even when the switching device is configured as only a single conversion valve.

[0016] The compression device has the following advantages: The delivery flow paths of one or more single-flow compressors or multi-flow compressors can be switchably compressed from either low pressure or medium pressure to a higher pressure, and in parallel connection therewith, the delivery flow paths of the remaining single-stage compressors or multi-stage compressors can compress the refrigerant from low pressure to a higher pressure. Thereby, the compression device can operate flexibly. The compression device can operate in a manner that can be switched from compression with only one pressure difference to two parallel-connected compressions with different pressure differences without two-stage operation of compressors connected in series. There is no fixed associated compressor or delivery flow path provided only for each compression stage respectively, so that space and materials are advantageously saved. The delivery flow paths or all the delivery flow paths or single-flow compressors in the compression device according to the invention can operate in parallel connection to compress the refrigerant from low pressure to a higher pressure, which is advantageous for the size of the volume flow to be compressed. In addition, when switching the compression device for operation with two different pressure differences, the delivery flow paths or single-flow compressors are not connected in series, so that the entire volume flow to be compressed is not significantly reduced advantageously. With the aid of the switching valve, an additional sensing mechanism is advantageously not required, but the switching is carried out directly in a pressure-related manner without complexity, without having to operate the valve directly for switching. In a switching valve, for example, with automatic flow-through of the refrigerant at an inlet with an instantaneous higher pressure and blocking at another inlet with an instantaneous lower pressure applied thereto, no additional pressure sensor is required. The compression device according to the invention with a switching device having one or more switching valves is thus a simple, material-saving and cost-effective embodiment, wherein the one / more switching valves do not have to be directly operated.

[0017] One embodiment of the compression device according to the invention is advantageous, the compression device comprising a multi-flow compressor, wherein the multi-flow compressor is designed as a piston compressor (Tauchkolbenverdichter) having a plurality of cylinders for a plurality of delivery flow paths. In such a multi-flow compressor, the plurality of delivery flow paths can operate particularly well in parallel connection to compress the refrigerant from low pressure to a higher pressure.

[0018] According to an advantageous improvement, one or more of the delivery flow paths in the single-flow compressors or in the multi-flow compressors are configured to be shut-off. The flexibility of the compression device is thereby particularly high. Thus, the size of the volume flow of the refrigerant to be compressed can be set according to requirements. Thereby, the power and thus the energy consumption of the compression device can be reduced according to requirements.

[0019] Preferably, the regulation is configured such that the shut-off and switching on of one / more shut-off single-flow compressors or delivery flow paths can be regulated by means of the regulation. Thereby, automatic control of the size of the volume flow of the refrigerant to be compressed can be achieved.

[0020] The object with respect to a refrigerant circuit having a heat economizer is achieved by the features detailed in the description. The problem is achieved by a refrigerant circuit which on the high-pressure side includes at least one condenser / gas cooler, the high-pressure side of the heat economizer, and a branch into a main branch and into a sub-branch which can be shut off for the refrigerant to flow through, wherein the sub-branch, which is open for a first sub-flow of the refrigerant, includes a first expansion mechanism and for this purpose includes the medium-pressure side of the heat economizer which is arranged downstream in the refrigerant flow direction, and the main branch, which is for a second sub-flow of the refrigerant in the case of division of the refrigerant flow, includes at least one second expansion mechanism and for this purpose includes at least one evaporator which is arranged downstream in the refrigerant flow direction, wherein the refrigerant circuit includes a compression device according to the invention for compressing the refrigerant, and a first suction inlet of the compression device is provided for the first sub-flow of the refrigerant from the medium-pressure side of the heat economizer via the sub-branch, and a second suction inlet of the compression device is provided for the refrigerant from at least one evaporator via the main branch, and the switching device of the compression device includes a changeover valve which has an outlet to one or more of a switchable delivery flow path or a switchable single-flow compressor and has the switching feasibility of the changeover valve for opening the valve flow-through of the refrigerant to the first suction inlet or the second suction inlet of the compression device.

[0021] The gas cooler / condenser can be a condenser for a refrigerant which is to be operated subcritically in the high-pressure region of the refrigerant circuit or a gas cooler for a refrigerant which is to be operated supercritically in the high-pressure region of the refrigerant circuit, or the gas cooler / condenser can be configured such that it can be used not only as a gas cooler but also as a condenser.

[0022] With regard to advantages and advantageous embodiments and refinements, the above description of the compression device according to the invention applies correspondingly thereto. In particular, the changeover valve automatically switches to the flow-through of the refrigerant at the suction inlet having the instantaneously higher pressure of the refrigerant and to the blocking at the other suction inlet at which the instantaneously lower pressure is exerted thereon. For this purpose, no additional pressure sensors are required. When the sub-branch preferably has a closable and controllable electronic expansion valve as the first expansion mechanism, the switching device of the compression device can be automatically switched during operation of the refrigerant circuit merely by controlling the first expansion mechanism. Thereby, by means of only one valve, not only can the expansion of the refrigerant be controlled but also the blocking and opening of the sub-branch can be controlled.

[0023] Preferably, the sub-branch can be opened or blocked for the flow-through of the refrigerant depending on whether the switching setting with an active heat economizer or the switching setting without an active heat economizer is exactly more economical. For this purpose, the setting of the compression can be well matched by means of the compression device according to the invention and in particular its switching device, without having to significantly change the volume flow of the refrigerant through the compression device.

[0024] According to an advantageous refinement, the first expansion mechanism includes MOP regulation. MOP stands for "maximum operating pressure", i.e., the maximum working pressure. The upper limit for the working pressure is regulated by means of MOP regulation, i.e., the maximum value of the pressure of the refrigerant after expansion. This makes it possible to better avoid an excessively high evaporation temperature of the refrigerant after flowing through the medium-pressure side of the economizer, which, for example, leaves more clearance space when dimensioning the economizer. For example, in a thermostatic expansion valve with MOP regulation, the filling quantity in the detector is limited such that from a specific evaporation temperature, the detector filling evaporates completely and thus the detector pressure no longer rises significantly. This therefore changes the force relationship acting on the diaphragm in the expansion valve towards closing the expansion valve when the evaporation pressure further rises, thereby limiting the evaporation pressure to the maximum value.

[0025] Preferably, the refrigerant circuit has a control device configured such that the first expansion mechanism can be controlled by means of the control device taking into account the superheat of the refrigerant before or at the first suction inlet of the compression device. By means of this control, the flow-through of the refrigerant through the secondary branch can be automatically controlled, and thus, for example, the switching setting can also be automatically controlled in a compression device according to the invention having a switching device including a changeover valve.

[0026] According to an advantageous embodiment, the control device is configured such that the first expansion mechanism can be controlled taking into account the power of the compression device and / or the temperature difference between the heat sink temperature at at least one condenser / gas cooler and the heat source temperature at at least one evaporator in the main branch. When the temperature difference is high enough for improving the power coefficient by means of the economizer, the control device can automatically open the flow-through of the first sub-stream of the refrigerant through the secondary branch and set the medium pressure of the refrigerant at the first suction inlet.

[0027] Preferably, the control device is configured such that, when switching the flow channel for conveying the first sub-stream of the refrigerant having a medium pressure, the first expansion mechanism and / or the second expansion mechanism can be controlled taking into account the regulation target of power coordination transmitted from the crank drive to the refrigerant in the respective compression space. Especially in a multi-flow piston compressor, this makes it possible to reduce the risk of crankshaft imbalance and thus minimize the disturbing noise of the compressor as well as reduce the susceptibility to damage and wear of the compression device.

[0028] According to an advantageous embodiment of a compression device with a delivery flow path having one or more switchable single-flow compressors or multi-flow compressors, the control device is configured such that, with the aid of the control device, it is possible to control the switching off and on of one or more switchable single-flow compressors or the delivery flow path, taking into account the power requirement of the compression device for the refrigerant circuit. Thereby, it is possible to operate the refrigerant circuit according to the invention particularly flexibly.

[0029] Preferably, there is provided a refrigerant circuit for a heating and / or air-conditioning facility for a vehicle, such as in particular a bus or a rail vehicle. A refrigerant circuit according to the invention with a compression device that can be operated flexibly and is material- and space-saving, including a regenerator, is particularly well-suited for this.

[0030] The object in terms of a method for operating a refrigerant circuit is achieved by the features detailed in the description. The object is achieved by a method for operating a refrigerant circuit according to the invention or a corresponding refrigerant circuit having a switching device without a conversion valve provided for switching one or more switchable delivery flow paths or single-flow compressors,

[0031] The method comprises the following steps:

[0032] Checking, taking into account the temperature difference between the temperature of the heat sink at at least one condenser / gas cooler and the temperature of the heat source at at least one evaporator in the main branch: whether the refrigerant circuit should be operated using the regenerator,

[0033] And, if the result of the previous checking step is affirmative, then performing the following steps:

[0034] aa) Opening or allowing to open a secondary branch provided for a first sub-stream of the refrigerant such that the refrigerant of the first sub-stream passes through the high-pressure side of the regenerator and the medium-pressure side of the regenerator after being depressurized to medium pressure in a first expansion mechanism, and

[0035] bb) Switching or allowing to switch one or more switchable delivery flow paths or switchable single-flow compressors in such a way that the switchable delivery flow path or switchable single-flow compressor is operated to compress the refrigerant of the first sub-stream from medium pressure, which is between low pressure and a higher pressure, to the higher pressure, where at the same time one or more delivery flow paths in the remaining delivery flow paths or one or more single-flow compressors in the remaining single-flow compressors are operated to compress the refrigerant of the second sub-stream from low pressure to the higher pressure, or

[0036] If the result of the checking step is negative, then performing the following steps:

[0037] (cc) Closing or allowing to close the secondary branch provided for the first sub-stream of the refrigerant, such that only the high-pressure side in the economizer is traversed by the refrigerant, and

[0038] (dd) Switching or allowing to switch one or more switchable delivery flow channels or switchable single-flow compressors in such a way that the switchable delivery flow channels or switchable single-flow compressors are operated to compress the refrigerant from the low pressure to a higher pressure from the main branch, wherein in a parallel line thereto, one or more of the remaining delivery flow channels in the remaining delivery flow channels or one or more of the remaining single-flow compressors in the remaining single-flow compressors are also operated simultaneously to compress the refrigerant from the low pressure to a higher pressure from the main branch.

[0039] An embodiment of the switching device without a switching valve may have one or more three-way switching valves controlled by a control device instead of, for example, a switching valve for switching in the method according to the invention.

[0040] An advantage is to consider the temperature difference between the heat sink at the condenser / gas cooler and the heat source at the evaporator to determine whether to use an economizer. The temperature difference can be simply determined by means of a temperature sensor and forms an important criterion for determining the effective use of the economizer in the refrigerant circuit.

[0041] According to an advantageous embodiment of the method, in the case of the following switching device, the switching setting for step bb) is carried out by opening the secondary branch and another switching setting for step dd) is carried out by closing the secondary branch. The switching device includes a switching valve having an outlet to one or more of the switchable delivery flow channels or switchable single-flow compressors and having a switching switch (Wechselschalten) for opening the valve passage of the refrigerant for the first suction inlet or the second suction inlet from the compression device. The switching valve is a simple type without an additional sensing mechanism, which switches the switchable delivery flow channels of the switchable single-flow compressor or multi-flow compressor. In particular, the following embodiment of the method is advantageous, wherein in the secondary branch, the first expansion mechanism is configured as an adjustable electronic expansion valve and is opened or held for step aa) and closed or held for step cc). Thus, for step aa) together with bb) and cc) together with dd), only the first expansion mechanism needs to be controlled, wherein additionally the superheat of the refrigerant in or at the first suction inlet of the compression device is controlled by means of the first expansion mechanism.

[0042] Advantageously, in the first step, the result of checking whether the economizer should be used for the operation of the refrigerant circuit depends on the economy of the use of the economizer. The secondary branch can be opened or blocked for the flow-through of the refrigerant depending on whether it is more economical with the switching setting of the active economizer or without the switching setting of the active economizer. For this purpose, the compression setting can be well matched by means of the compression device and especially its switching device without significantly changing the volume flow of the refrigerant through the compression device.

[0043] According to an advantageous refinement of the method, in the case of operating the refrigerant circuit with an economizer, for the coordinated control objective in the respective compression space of the crank drive of the multi-flow piston compressor of such a configured compression device, the first expansion mechanism is controlled in such a way that the operating point optimally selects the superheat of the refrigerant before or at the first suction inlet of the compression device.

[0044] Thereby, the imbalance of the crankshaft of the compression device is resisted, which reduces the disturbing noise, vulnerability and wear of the compression device.

[0045] According to an advantageous embodiment, the method according to the invention for operating a refrigerant circuit of a compression device with a delivery flow path having one or more switchable single-flow compressors or multi-flow compressors includes additional steps: determining the power requirement of the compression device for the refrigerant circuit and switching off or switching on the switchable single-flow compressor or one and / or more switchable single-flow compressors or delivery flow paths in the delivery flow path according to the determined power requirement. Thereby, an additional combinability of the switching of such a compression device is used. In this way, the refrigerant circuit is made particularly flexible to match the respective instantaneous demand. Thereby, the refrigerant circuit is operated energy-savingly at part load. Description of the Drawings

[0046] Embodiments of the invention are illustrated according to the drawings.

[0047] The drawings show

[0048] Figure 1a An embodiment of a compression device according to the invention with a multi-flow compressor in a switching setting of the switching device is shown in a schematic diagram;

[0049] Figure 1b The embodiment shown in the compression device according to the invention in another switching setting of the switching device is shown in a schematic diagram Figure 1a is shown in;

[0050] Figure 2aAnother embodiment of a compression device according to the invention with a multi-flow compressor and the switching settings of a switching device are shown in a schematic illustration, the multi-flow compressor having a switchable delivery flow path;

[0051] Figure 2b In a schematic illustration, the embodiment of the compression device according to the invention in another switching setting of the switching device is shown in Figure 2a the embodiment shown;

[0052] Figure 3a In a schematic illustration, an embodiment of a refrigerant circuit of a compression device according to the invention with the switching settings of a switching device is shown;

[0053] Figure 3b In a schematic illustration, the embodiment of the refrigerant circuit of a compression device according to the invention in another switching setting of the switching device is shown in Figure 3a the embodiment shown;

[0054] Figure 4 In a schematic illustration, an embodiment of a refrigerant circuit for operating by means of a method according to the invention is shown;

[0055] Figure 5 An embodiment of a method according to the invention for operating a refrigerant circuit is shown as a flow chart; and

[0056] Figure 6 Another embodiment of a method according to the invention for operating a refrigerant circuit is shown as a flow chart. DETAILED DESCRIPTION

[0057] All figures are to be understood as schematic. For the purpose of increased clarity of the illustration, a scale-compliant depiction is dispensed with.

[0058] In Figure 1a a schematic illustration, an embodiment of a compression device 1 according to the invention with a multi-flow compressor 3 in a switching setting of a switching device 5 is shown.

[0059] The multi-flow compressor 3 has four delivery flow paths 9, 9a in a compressor housing 7, the delivery flow paths each having a cylinder 11. Embodiments of the multi-flow compressor 3 with two, three or more than four delivery flow paths 9, 9a are also possible. The multi-flow compressor 3 is configured as a piston compressor (Tauchkolbenverdichter). Other known suitable types of multi-flow compressors 3 are also conceivable.

[0060] The four delivery channels 9, 9a can operate in parallel connection to compress the refrigerant from a low pressure to a higher pressure. The outlets of the delivery channels 9, 9a for the refrigerant compressed to a higher pressure in the cylinder 11 are at the same pressure level and lead jointly into the refrigerant line. One of the four delivery channels 9a is switchable such that it can operate in a switching setting to compress the refrigerant of a first sub-stream from a medium pressure between a low pressure and a higher pressure to a higher pressure, wherein the remaining three delivery channels 9 can operate simultaneously to compress the refrigerant of a second sub-stream from a low pressure to a higher pressure.

[0061] The following variant of the multi-flow compressor 3 is also feasible, in which more than one delivery channel 9a is configured switchably. A switching device 5 arranged outside the compressor housing 7 is provided for switching, and the switching device is configured as a changeover valve in this case.

[0062] As a feasible alternative, the switching device 5 can be located in the compressor housing 7.

[0063] An inlet 13a of the switching device 5 is provided for the refrigerant having the same pressure as in the inlets of the three non-switchable delivery channels 9. Upstream of it in the set refrigerant flow direction, for the inflow of the refrigerant having a low pressure, the second suction inlet 15 of the compression device 1 is provided as the low-pressure port of the multi-flow compressor 3. Another inlet 13b of the switching device 5 is provided as a medium-pressure connection port with the first suction inlet of the compression device 1 for a first sub-stream of the refrigerant having a medium pressure, i.e., a pressure different from the pressure in the inlets of the three non-switchable delivery channels 9 provided for the refrigerant having a low pressure. The outlet of the switching device 5 leads to the switchable delivery channel 9a. The switching device 5 configured as the only changeover valve has two switching settings in operation. In one switching setting, one inlet 13a is open and its other inlet 13b is closed, and in the other switching setting, it is exactly the opposite. Thus, the following inlet of the two inlets 13a, 13b of the switching device 5 is open: at the inlet where the applied pressure of the refrigerant is higher than at the other inlet. The closing body 17 configured as a ball in the switching device 5 closes the following inlets 13a, 13b: at the inlets where a lower pressure is applied. In Figure 1a In, in the switching device 5, the inlet 13a is open for the parallel connection of all four delivery channels 9, 9a for compressing the refrigerant from a low pressure to a higher pressure and the other inlet 13b is closed. At the other inlet 13b, in this case during operation, no medium pressure is applied, but a pressure lower than the low pressure of the refrigerant at the second suction inlet 15 is applied.

[0064] In Figure 1b is shown with the same reference numerals for the compression device 1 in another switching setting of the switching device 5 inFigure 1a The embodiment shown therein. In the switching setting shown there, the inlet 13b of the switching device 5 is opened as a medium-pressure connection port, a refrigerant with medium pressure is applied at the medium-pressure connection port during operation, and another inlet 13a for the refrigerant of the second suction inlet 15 is closed. Therefore, the switchable delivery flow channel 9a is switched to compress the refrigerant of the first sub-flow with medium pressure from the medium-pressure connection port to a higher pressure. Here, three non-switchable delivery flow channels 9 are connected to compress the refrigerant of the second sub-flow with low pressure from the second suction connection end 15 to a higher pressure.

[0065] In Figure 2a Another embodiment of the compression device 1 with a multi-flow compressor 3 according to the invention in a switching setting of the switching device 5 is schematically shown therein. The multi-flow compressor 3 has four delivery flow channels 9, 9a, 9b in the compressor housing 7, and the delivery flow channels respectively have cylinders 11. The multi-flow compressor 3 is configured as a piston compressor. The four delivery flow channels 9, 9a, 9b can be operated in parallel connection to compress the refrigerant from low pressure to a higher pressure. The outlets of the four delivery flow channels 9, 9a, 9b for the refrigerant to be compressed to a higher pressure in the cylinders 11 are at the same pressure level and jointly lead to the refrigerant pipeline. Two of the four delivery flow channels 9a, 9b can be switched so that they can be operated in a switching setting to compress the refrigerant of the first sub-flow from a medium pressure between low pressure and higher pressure to a higher pressure, and the remaining two delivery flow channels 9 can be operated simultaneously to compress the refrigerant of the second sub-flow from low pressure to a higher pressure.

[0066] The switching device 5 provided within the compressor housing 7 is provided for switching, and in this case, the switching device is only configured as a single changeover valve. As a feasible alternative, the switching device 5 can be located outside the compressor housing 7.

[0067] One inlet 13a of the switching device 5 is provided for the refrigerant having the same pressure as that in the inlets of the two non-switchable delivery flow channels 9. Upstream of it in the set refrigerant flow direction, a second suction inlet 15 of the compression device 1, which serves as a low-pressure connection port, is provided for the inflow of the refrigerant with low pressure. Another inlet 13b of the switching device 5 is similarly provided after a first suction inlet 37 for the first sub-flow of the refrigerant with medium pressure, that is, a pressure different from that in the inlets of the two non-switchable delivery flow channels 9 provided for the refrigerant with low pressure. The outlet of the switching device 5 leads to the two switchable delivery flow channels 9a, 9b. The switching device 5 configured as a changeover valve has two switching settings during operation in this case. The switching device 5 together with its switchable switching settings by means of the spherical closing body 17 of the changeover valve corresponds to regardingFigure 1a the described switching setting. Thus, the following inlet of the two inlets 13a, 13b of the switching device 5 is opened: at this inlet, the applied pressure of the refrigerant is higher than the pressure at the other inlet.

[0068] In Figure 2a In the switching device 5 configured as a changeover valve, the inlet 13a is opened for the parallel line of all four delivery channels 9, 9a, 9b for the refrigerant having a low pressure from the second suction inlet 15 and the other inlet 13b of the switching device 5 is closed. However, the delivery channel 9b of the switchable delivery channels 9a, 9b is configured to be shut-off. The delivery channel can, when switched on, operate in parallel connection with three other delivery channels 9, 9a to compress the refrigerant having a low pressure to a higher pressure. And in Figure 2a it, the delivery channel is shown shut-off. The three-way valve 19 switchable by means of the regulating device 21 at the outlet of the shut-off delivery channel 9b is switched here to block towards the high-pressure region and to lead the refrigerant back to the inlet of the shut-off delivery channel 9b, so that there is a short-circuit line to the suction region of the thus shut-off delivery channel 9b. The shut-off of the delivery channel 9b is especially provided for operating the compression device 1 having a reduced power as, for example, in part-load operation. Thus, the shut-off delivery channel 9b can be switched in two ways. The delivery channel is configured to be shut-off and switchable.

[0069] Embodiments of the multi-stream compressor 7 can be envisaged, in which more than one shut-off delivery channel 9b of the delivery channels 9, 9a, 9b connectable in parallel are provided.

[0070] In Figure 2b the embodiment shown in Figure 2a is shown with the same reference numerals in another switching setting of the switching device 5. In the switching setting shown there, the inlet 13b of the switching device 5 is opened as a medium-pressure connection port, at which the refrigerant having a medium pressure is applied during operation, and the other inlet 13a for the refrigerant from the second suction inlet 15 is closed. Thus, the two switchable delivery channels 9a, 9b are switched to compress the refrigerant of the first sub-stream having a medium pressure from the first suction inlet to a higher pressure. The shut-off delivery channel 9b is shown switched on here. The three-way valve 19 switchable by means of the regulating device 21 at the outlet of the shut-off delivery channel 9b is switched to open towards the high-pressure region and to block the leading-back of the refrigerant to the inlet of the shut-off delivery channel 9b.

[0071] It is also conceivable to have further known suitable types of shut-off delivery flow paths, such as, for example, block base shut-off, where a bypass is opened via a magnetic valve between two adjacent convective cylinders, whereupon the first cylinder then pushes the gas volume into the second cylinder and vice versa. Then, there is thus a short-circuit connection of the refrigerant between the cylinders.

[0072] Furthermore, two non-switchable delivery flow paths 9 are connected to compress the refrigerant of the second sub-stream with low pressure from the second suction inlet 15 to a higher pressure.

[0073] In Figure 3a FIG. schematically shows an embodiment of a refrigerant circuit 23 with a compression device 1 according to the invention in the switching setting of a switching device 5. The refrigerant circuit 23 extends on the high-pressure side from the output of the compression device 1 to the condenser / gas cooler 25 and then to the high-pressure side of the economizer 27 and subsequently to a branch 29. In the branch 29, the refrigerant line branches into a main branch 31 and a secondary branch 33. An alternative arrangement is also conceivable, where the branch 29 is in front of the high-pressure side of the economizer 27 which is subsequently in the main branch 31 in the refrigerant flow direction. In the secondary branch 33, the refrigerant line leads to a first expansion mechanism 35, which is configured as a closable and adjustable electronic expansion valve. In operation, the refrigerant flow through the secondary branch 33 can be shut off and switched on by closing and opening the first expansion mechanism 35. In the open first expansion mechanism 35, the refrigerant of the first sub-stream for the medium pressure expands. Downstream of the first expansion mechanism 35 in the refrigerant flow direction, the medium-pressure side of the economizer 27 is provided in the secondary branch 33. Subsequently, the secondary branch 33 leads to a first suction inlet 37 of the compression device 1, which in this case forms the medium-pressure connection port of an inlet 13b of the switching device 5 configured as a changeover valve.

[0074] Starting from the branch 29, the main branch 31 leads to a second expansion mechanism 39, which is configured to expand the refrigerant flowing through the main branch 29 during operation to a low pressure. For this purpose, an evaporator 41 is provided downstream in the refrigerant flow direction in the main branch 31. Starting from the evaporator 41, the refrigerant evaporated there into suction during operation flows to the second suction inlet 15 of the compression device 1. The compression device 1 includes a multi-flow compressor 3 configured as a piston compressor, which has four cylinders 11 with four delivery channels 9, 9a, 9b. The switching device 5 is located outside the compressor housing 7. The outlet of the switching device 5 configured as the only changeover valve leads into a switchable delivery channel 9a of the multi-flow compressor 3. Of the remaining three non-switchable delivery channels 9, 9b, two are configured as switchable-off delivery channels 9b. For this purpose, a three-way valve 19 is present at their outlet respectively, which switches to block towards the high-pressure region and return the refrigerant to the inlet of the corresponding switchable-off delivery channel 9b when the corresponding switchable-off compressor channel 9b is switched off.

[0075] The four delivery channels 9, 9a, 9b can operate in parallel connection to compress the refrigerant from a low pressure to a higher pressure. The outlets for the refrigerant compressed to a higher pressure in the cylinders 11 leading from the four delivery channels 9, 9a, 9b are at the same pressure level for the refrigerant and lead together into the refrigerant line to the condenser / gas cooler 25. One switchable delivery channel 9a can be switched such that it can operate in a switching setting to compress the refrigerant of a first sub-stream from a medium pressure between a low pressure and a higher pressure to a higher pressure, where the remaining three delivery channels 9, 9b can operate simultaneously to compress the refrigerant of a second sub-stream from a low pressure to a higher pressure.

[0076] The inlet 13a of the switching device 5 is configured for refrigerant having the same pressure as in the inlets of the three non-switchable delivery channels 9, 9b. Upstream of it in the set refrigerant flow direction, for the inflow of refrigerant having a low pressure, the second suction inlet 15 is provided as the low-pressure connection port of the multi-flow compressor 3. The other inlet 13b of the switching device 5 is configured as the first suction inlet 37 of the compression device 1 for the first sub-stream of refrigerant having a medium pressure. The closing body 17 configured as a ball in the switching device 5 configured as a changeover valve closes the following inlets 13a, 13b, at which a lower pressure is applied. In Figure 3a it, in the switching device 5 configured as a changeover valve, the inlet 13a is open for the parallel lines of all the delivery channels 9, 9a, 9b that are not switched off instantaneously for compressing the refrigerant from a low pressure to a higher pressure and the other inlet 13b is closed. At the other inlet 13b, a lower pressure is applied due to the switched-off secondary branch 33 compared to the low pressure of the refrigerant passing through the second suction inlet 15 from the main branch 31. The control device 43 is in the refrigerant circuit 23 atFigure 3a In the setting shown, the two three-way valves 19 at the respective outlets of the two switchable delivery channels 9b are controlled such that the refrigerant flows through to the condenser / gas cooler 25 in the high-pressure region and the return of the refrigerant to the inlet of the respective switchable delivery channel 9b is blocked. In addition, the first expansion mechanism 35 is regulated by the control device 43 to be closed or blocked, such that the secondary branch 33 is blocked for the flow-through of the refrigerant, so that the undivided refrigerant flow during operation flows through the main branch 31 to the second suction inlet 15.

[0077] One or two switchable delivery channels 9b can be switched off depending on the power requirement of the compression device 1 for the refrigerant circuit 23, wherein, by means of the control device 43, the respective switchable three-way valve 19 at the outlet of the respective switchable delivery channel 9b is switched to block towards the high-pressure region and to return the refrigerant to the inlet of the switchable delivery channel 9b, such that there is a short-circuit connection to the suction region of the switchable delivery channel, so that the switchable delivery channel is switched off. Other known suitable types of switchable delivery channels are also conceivable, such as, for example, cylinder block base switching off.

[0078] For example, the use of a multi-flow compressor 3 with one or two switched-off delivery channels 9b is suitable during part-load operation of the refrigerant circuit 23.

[0079] In Figure 3b the refrigerant circuit 23 of the compression device 1 in another switching setting of the switching device 5 is shown with the same reference numerals as in Figure 3a the embodiment shown therein. In the switching setting shown there, the inlet 13b of the switching device 5 is opened as the first suction inlet 37, at which, during operation, the refrigerant of the first sub-stream with medium pressure is applied via the secondary branch 33, and the other inlet 13a is closed for the refrigerant from the second suction inlet 15. Thus, the switchable delivery channel 9a is switched for compressing the refrigerant of the first sub-stream with medium pressure from the secondary branch 33 to a higher pressure. The division of the refrigerant flow takes place at the branch 29. The first expansion mechanism 35 is controlled by the control device 43 for this purpose such that the first sub-stream of the refrigerant flowing through the secondary branch 33 expands accordingly. Here, the superheating of the refrigerant before the first suction inlet 37 of the compression device 1 is taken into account.

[0080] The first expansion mechanism 35 has a MOP regulating device for limiting the maximum pressure before the first suction inlet 37. In addition, three non-switchable delivery flow channels 9, 9b are connected for compressing the refrigerant of the second sub-flow with low pressure through the main branch 31 from the second suction connection port 15 serving as a low-pressure connection port to a higher pressure. The economizer 27 is switched to operation. Its high-pressure side and its medium-pressure side are flowed through by the refrigerant during operation in a countercurrent arrangement. The size of the economizer, together with its heat transfer surface, is matched to the working volume ratio of the switchable delivery flow channel 9a to the three non-switchable delivery flow channels 9, 9b and to the maximum temperature difference between the heat source at the evaporator 41 and the heat sink at the condenser / gas cooler 25. The control device 43 controls the first expansion mechanism 35 taking into account the temperature difference between the temperature of the heat sink at at least one condenser / gas cooler 25 and the temperature of the heat source at at least one evaporator 41 in the main branch 31. In the case of a high temperature difference, the setting shown in Figure 3b is switched by the control device 43, and in the case of a low temperature difference, the setting shown in Figure 3a is switched.

[0081] The refrigerant circuit 23 is provided for a heating / air-conditioning facility of a vehicle, such as a bus or a rail vehicle for example.

[0082] In this case, the refrigerant circuit 23 is designed to be pressure-resistant correspondingly for the supercritical operation of the refrigerant in the high-pressure region. The refrigerant is CO2 in this case. A variant is conceivable in which the refrigerant circuit 23 can be designed for subcritical operation, and the refrigerant circuit can operate subcritically with the refrigerant R1234yf for example.

[0083] In Figure 4FIG. schematically shows an embodiment of a refrigerant circuit 23 for operating by means of the method according to the invention. On the high-pressure side, the compressed refrigerant is guided from the outlet of the compression device 1 through the condenser / compressor 25 to the branch 29 into the main branch 31 and the sub-branch 33 which can be shut off for the refrigerant to flow through. In the main branch 31, there follows the high-pressure side of the economizer 27 and then the second expansion mechanism 39, which is configured as an electronically controllable expansion valve that can be regulated by the control device 43. Downstream of the second expansion mechanism 39 in the refrigerant flow direction, there is an evaporator 41 for evaporating the refrigerant, and the refrigerant then flows as suction to the second suction inlet 15 of the compression device 1 during operation at low pressure. In the sub-branch 33, a first expansion mechanism 35 configured as an electronically controllable and closable expansion valve is provided upstream of the medium-pressure side of the economizer 27 in the refrigerant flow direction. In the sub-branch 33, downstream of the medium-pressure side of the economizer 27, there is a first suction inlet 37 of the compression device 1 provided for suction at medium pressure, and this first suction inlet is also an inlet 13b of the switching device 5. The switching device 5 includes a three-way switching valve that can be switched by the control device 43, whereby the switching device is different from the compression device according to the invention. The second inlet 13a thereof is provided for the refrigerant from the second suction inlet 15. The compression device 1 has three single-flow compressors 47, 47a, which are configured such that they can be operated in parallel connection to compress the refrigerant from low pressure to a higher pressure. The single-flow compressor 47a is switchably arranged at the output of the switching device 5 such that it can be operated in the switching setting of the three-way switching valve of the switching device 5 to compress the refrigerant of the first sub-stream flowing through the open sub-branch 33 from medium pressure between low pressure and higher pressure to a higher pressure, and the remaining two single-flow compressors 47 can be operated simultaneously to compress the refrigerant of the second sub-stream flowing through the main branch 31 from low pressure to a higher pressure. The control device 43 controls the corresponding switching setting by the corresponding switching of the three-way switching valve of the switching device 5 and the first expansion mechanism 35 for the refrigerant at low pressure from the second suction inlet 15 or the refrigerant at medium pressure from the first suction inlet 37 to flow through the switchable single-flow compressor 47a.

[0084] The control device 43 controls the power of the first expansion mechanism 33, the switching device 5, the second expansion mechanism 39, and the single-flow compressors 47, 47a taking into account the superheat of the refrigerant at the first suction inlet 37 of the compression device 1 and the temperature difference between the temperature of the heat sink at the condenser / gas cooler 25 and the temperature of the heat source at at least one evaporator 41 in the main branch 31.

[0085] In Figure 5 FIG. shows in a flow diagram for operating in Figure 4An embodiment of the refrigerant cycle circuit or the method of the refrigerant cycle circuit according to the invention, as shown, for example, in Figure 3a and Figure 3b the refrigerant cycle circuit shown.

[0086] In a first step 100, measurement data are received by the control device, such as the temperature of the heat sink especially at the condenser / compressor and the temperature of the heat source at the evaporator of the refrigerant cycle circuit. In a first step 110, it is checked according to the received measurement data whether the refrigerant cycle circuit should be operated using a regenerator. In this check, the temperature difference between the temperature of the heat sink at at least one condenser / gas cooler and the temperature of the heat source at at least one evaporator of the main branch is considered, where the decision depends especially on the economy of using the regenerator. In the case of a determined high temperature difference between the heat source and the heat sink, the use of the regenerator is more economical compared to the situation with a low temperature difference.

[0087] If as a result of the check in step 110 the decision 120 is affirmative for the use of the regenerator, i.e. "yes", then in a subsequent step 130 the secondary branch is opened or permitted to be opened for the passage of the first sub - stream of the refrigerant, such that the refrigerant passes through the high - pressure side of the regenerator and the first sub - stream of the refrigerant depressurized to the medium pressure in the first expansion mechanism passes through the medium - pressure side of the regenerator.

[0088] In a step 140, which is usually carried out simultaneously with step 130, one or more of the switchable delivery flow channels or single - flow compressors are switched or permitted to be switched such that they operate to compress the refrigerant of the first sub - stream from the secondary branch from a medium pressure, for example 40 bar, between a low pressure, for example 20 bar, and a higher pressure, for example 100 bar, to a higher pressure, while simultaneously operating one or more of the remaining delivery flow channels or one or more of the remaining single - flow compressors to compress the refrigerant of the second sub - stream from the main branch from the low pressure to a higher pressure.

[0089] However, if as a result of the check in step 110 the decision 120 is against the use of the regenerator, i.e. "no", then in a subsequent step 130a the secondary branch provided for the first sub - stream of the refrigerant is closed or permitted to be closed, such that the refrigerant only passes through the high - pressure side of the regenerator.

[0090] In step 140a, which is typically carried out simultaneously with step 130a, one or more switchable delivery channels in a switchable delivery manifold or a switchable single-flow compressor, or the switchable single-flow compressor, are switched or allowed to be switched in such a way that they operate to compress the refrigerant from the main branch from a low pressure, for example 30 bar, to a higher pressure, for example 90 bar, and one or more delivery channels in the remaining delivery manifolds of the compression device or one or more single-flow compressors in the remaining single-flow compressors are also operated in parallel therewith and simultaneously to compress the refrigerant from the main branch from a low pressure to a higher pressure.

[0091] After a preset period of time, for example one second, after step 140 or 140a, the method is started again in a manner starting from step 100.

[0092] The check in step 110 is automatically carried out in the control device of the refrigerant circuit, where the received measurement data transmitted by the temperature sensors to the control device are processed, the temperature sensors being used to measure the temperature of the heat source at the evaporator and the temperature of the heat sink at the condenser / gas cooler, as well as the temperature of the refrigerant at the first and second suction inlets of the compression device.

[0093] The first expansion mechanism is configured as an adjustable electronic expansion valve which is opened or kept open to carry out step 130 and closed or kept closed to carry out step 130a.

[0094] When carrying out the method for operating a refrigerant circuit having a switching device as shown, for example, in Figure 3a and Figure 3b the switching setting for step 140 is automatically carried out by opening the secondary branch for refrigerant flow-through and the other switching setting for step 140a is carried out by closing the secondary branch, the switching device including a changeover valve which has outlets to one or more of the switchable delivery channels or single-flow compressors and has a changeover switch for opening the valve flow-through for the refrigerant from the first or second suction inlet of the compression device. The changeover valve switches automatically according to the respective sign of the pressure difference of the refrigerant between the first and second suction inlets. Thus, strictly speaking, steps 130 and 140 are carried out in one step in the switching device including the changeover valve. The corresponding applies to steps 130a and 140a.

[0095] In Figure 6 a further embodiment of the method for operating a refrigerant circuit according to the invention is shown as a flow diagram, as for example in Figure 3a and Figure 3bThe refrigerant cycle circuit shown. The compression device has a multi-flow compressor configured as a piston compressor having a plurality of cylinders, wherein at least one delivery flow path is switchable and two delivery flow paths are closable.

[0096] In a first step 200, measurement data is received by the control device, such as the temperature of the heat sink at the condenser / gas cooler transmitted by a temperature sensor, the temperature of the heat source at the evaporator of the refrigerant cycle circuit, and the temperature of the refrigerant at the first and second suction inlets of the compression device. And measurement data transmitted by an acoustic sensor at the compression device.

[0097] In a subsequent step 210, the power requirement for the compression device of the refrigerant cycle circuit is determined by means of the received measurement data. Based on the determined power requirement, in step 220, one or more of the closable delivery flow paths are closed or opened or kept closed or opened according to the determined power requirement. For example, the power requirement for part-load operation of the refrigerant cycle circuit is more likely to be small, such that one or even two of the closable delivery flow paths are closed.

[0098] The following steps are performed: checking 230 the use of the economizer and deciding 240, opening 250 or closing 250a the secondary branch, and switching 260 the switchable delivery flow path for the refrigerant with medium pressure from the secondary branch or switching 260a the switchable delivery flow path for the refrigerant with low pressure from the main branch, as in steps 110, 120, 130, 130a, 140, and 140a described in Figure 5 In this case, the switching of steps 260 and 260a is automatically performed by opening 250 or closing 250a the secondary branch, because the switching device is configured as a changeover valve such that the inlet where the higher pressure is applied is always automatically opened and the other inlet is closed.

[0099] Furthermore, in the Figure 6 method shown, after the step of switching 260 the switchable delivery flow path for the first sub-stream of the refrigerant from the secondary branch with medium pressure, additional steps 270 and 280 are performed, in which one or more of the remaining unclosed delivery flow paths are operated simultaneously to compress the refrigerant of the second sub-stream from the main branch from low pressure to a higher pressure.

[0100] In step 270, for the coordinated control target in the corresponding compression space of the crank drive of the multi-flow plunger compressor, the optimized operating point is determined by means of the measurement data received by the control device in step 200. Here, in particular, the aspect of the smallest possible sound emission of the compression device is also taken into account. Due to the asymmetric load of the crankshaft of the multi-flow compressor, the operating conditions have changed. The multi-flow compressor thus has an increased noise output and vibration output to the outside. The optimized operating point has an unnecessary thermodynamically optimized superheating of the refrigerant before or at the first suction inlet in order to reduce the load asymmetry of the cylinder to a tolerable level.

[0101] In a subsequent step 280 , the first expansion mechanism is controlled in such a way that the operating point is selected to optimize the superheating of the refrigerant before or at the first suction inlet of the compression device.

[0102] After a predefined time period of, for example, two seconds, the execution of the method begins again after step 280 or 260 a by starting again with step 200 .

Claims

1. A compression device (1), the compression device comprising a plurality of single - flow compressors (47, 47a) or a multi - flow compressor (3) having a plurality of delivery channels (9, 9a, 9b), wherein the delivery channels (9, 9a, 9b) or the single - flow compressors (47, 47a) are configured such that the delivery channels or the single - flow compressors can operate in parallel connection to compress a refrigerant from a low pressure to a higher pressure, and wherein one or more of the plurality of delivery channels (9, 9a, 9b) or single - flow compressors (47, 47a) are switchably configured such that the one or more delivery channels or single - flow compressors can operate in a switched setting to compress a first sub - stream of the refrigerant from an intermediate pressure between the low pressure and the higher pressure to the higher pressure, and wherein simultaneously, the remaining delivery channels or single - flow compressors of the plurality of delivery channels (9, 9a, 9b) or single - flow compressors (47, 47a) can operate to compress a second sub - stream of the refrigerant from the low pressure to the higher pressure. Characterized in that, the compression device (1) has at least one switching device (5), the switching device being configured such that the switching device includes one or more switching valves and is provided for switching the switchable one or more delivery channels (9, 9a, 9b) or single - flow compressors (47, 47a).

2. The compression device (1) according to claim 1, Characterized in that, the multi - flow compressor (3) is configured as a piston compressor having a plurality of cylinders (11) for a plurality of delivery channels (9, 9a, 9b).

3. The compression device (1) according to claim 1 or 2, Characterized in that, one or more of the single - flow compressors (47, 47a) or the delivery channels (9, 9a, 9b) of the multi - flow compressor (3) are configured to be shut - off.

4. A refrigerant circuit (23), the refrigerant circuit comprising, on the high - pressure side, at least one condenser / gas cooler (25), the high - pressure side of a heat economizer (27), and a branch point (29) into a main branch (31) and into a sub - branch (33) that can be shut - off for refrigerant flow, wherein the sub - branch (33) that is open for a first sub - stream of the refrigerant includes a first expansion mechanism (35) and for this purpose includes the intermediate - pressure side of the heat economizer (27) arranged downstream in the refrigerant flow direction, and the main branch (31) that is provided for a second sub - stream of the refrigerant in the case of refrigerant flow division includes at least one second expansion mechanism (39) and for this purpose includes at least one evaporator (41) arranged downstream in the refrigerant flow direction. Characterized in that, The refrigerant cycle circuit (23) includes a compression device (1) according to any one of claims 1 to 3 for compressing refrigerant, wherein a first suction inlet (37) of the compression device (1) is provided for a first sub-stream of refrigerant from the medium-pressure side of the economizer (27) through the secondary branch (33), and a second suction inlet (15) of the compression device (1) is provided for refrigerant from the at least one evaporator (41) through the main branch (31), and the switching device (5) of the compression device (1) includes a switching valve, the switching valve having an outlet to one or more switchable delivery channels (9, 9a, 9b) or a switchable single-flow compressor (47, 47a) and having the switching feasibility of the switching valve for opening the valve flow-through for refrigerant from the first suction inlet (37) or the second suction inlet (15) of the compression device (1).

5. The refrigerant cycle circuit (23) according to claim 4, characterized in that, the first expansion mechanism (35) is configured as a closable and adjustable electronic expansion valve.

6. The refrigerant cycle circuit (23) according to claim 4 or 5, characterized in that, the first expansion mechanism (35) includes a MOP control device.

7. The refrigerant cycle circuit (23) according to any one of claims 4 to 6, characterized in that, the refrigerant cycle circuit has a control device (43) configured such that the first expansion mechanism (35) can be controlled by means of the control device taking into account the superheat of the refrigerant before or at the first suction inlet (37) of the compression device (1).

8. The refrigerant cycle circuit (23) according to any one of claims 4 to 7, characterized in that, the control device (43) is configured such that the first expansion mechanism (35) can be controlled taking into account the power of the compression device (1) and / or the temperature difference between the temperature of the heat sink at the at least one condenser / gas cooler (25) and the temperature of the heat source at the at least one evaporator (41) in the main branch.

9. The refrigerant cycle circuit (23) according to any one of claims 4 to 8, the refrigerant cycle circuit having a compression device (1) according to claim 2, characterized in that, the control device (43) is configured such that, in the case of switching the delivery channels (9, 9a, 9b) for a first sub-stream of refrigerant having a medium pressure, the first expansion mechanism (35) and / or the second expansion mechanism (39) can be controlled taking into account a coordinated control target of the power transmitted from the crank drive mechanism to the refrigerant in the corresponding compression space.

10. The refrigerant cycle circuit (23) according to any one of claims 4 to 9, characterized in that, The refrigerant circuit is provided for a heating and / or air conditioning installation for a vehicle, in particular a bus or a rail vehicle.

11. A method for operating a refrigerant circuit (23) according to any one of claims 4 to 10, wherein however a switching device (5) provided for switching one or more switchable delivery flow paths (9, 9a, 9b) or single-flow compressors (47, 47a) is not limited to a switching device having one or more changeover valves, characterized in that the following steps are provided: a) checking (110, 230) taking into account the temperature difference between the temperature of the heat sink at the at least one condenser / gas cooler (25) and the temperature of the heat source at the at least one evaporator (41) in the main branch (31): whether the refrigerant circuit (23) should be operated using the economizer (27), b) if the result of step a) is affirmative, then the following steps are carried out: aa) opening or allowing to open (130, 250) the secondary branch (33) provided for the first sub-stream of refrigerant such that the refrigerant flows through the high-pressure side of the economizer (27) and the first sub-stream of refrigerant depressurized to medium pressure in the first expansion mechanism (35) flows through the medium-pressure side of the economizer (27), and bb) switching or allowing to switch (140, 260) the one or more switchable delivery flow paths (9, 9a, 9b) or the switchable single-flow compressors (47, 47a) in such a way that the one or more switchable delivery flow paths or the switchable single-flow compressors are operated to compress the first sub-stream of refrigerant from a medium pressure between a low pressure and a higher pressure to the higher pressure, wherein at the same time one or more of the remaining delivery flow paths (9, 9a, 9b) or one or more of the remaining single-flow compressors (47, 47a) are operated to compress the second sub-stream of refrigerant from the low pressure to the higher pressure, or c) if the result of step a) is negative, then the following steps are carried out: cc) closing or allowing to close (130a, 250a) the secondary branch (33) provided for the first sub-stream of refrigerant such that the refrigerant only flows through the high-pressure side of the economizer (27), and dd) switching or allowing to switch (140a, 260a) the one or more switchable delivery flow paths (9, 9a, 9b) or the switchable single-flow compressors (47, 47a) in such a way that the one or more switchable delivery flow paths or the switchable single-flow compressors are operated to compress the refrigerant from the main branch (31) from the low pressure to the higher pressure, wherein one or more of the remaining delivery flow paths (9, 9a, 9b) or one or more of the remaining single-flow compressors (47, 47a) are also operated in parallel connection therewith to compress the refrigerant from the main branch (31) from the low pressure to the higher pressure.

12. The method according to claim 11, characterized in that In the switching device (5), the switching setting for step bb) is carried out by opening the secondary branch (33) and another switching setting for step dd) is carried out by closing the secondary branch: The switching device includes a changeover valve which has an outlet to one or more switchable delivery flow channels (9, 9a, 9b) or single-flow compressors (47, 47a) and has a changeover switch for opening a valve flow-through for refrigerant from the first suction inlet (37) or the second suction inlet (15) of the compression device (1).

13. The method according to claim 11 or 12, characterized in that in step a), the result of the check (110, 230) as to whether the refrigerant circuit (23) should be operated using the economizer (27) depends on the economy of use of the economizer (27).

14. The method according to any one of claims 11 to 13, characterized in that in the case of a compression device (1) of a piston compressor configured with a plurality of cylinders (11) for a plurality of delivery flow channels (9, 9a, 9b), for a coordinated control target in the respective compression spaces of the crank drive of the multi-flow piston compressor, in the case of step b), the first expansion mechanism (35) is controlled in such a way that the superheat of the refrigerant before or at the first suction inlet (37) of the compression device (1) is optimally selected for the operating point.

15. The method for operating a refrigerant circuit (23) having the compression device (1) according to any one of claims 11 to 14, wherein one or more of the single-flow compressors (47, 47a) or the delivery flow channels (9, 9a, 9b) of the multi-flow compressor (3) are configured to be shut-off, characterized in that there is an additional step: - determining (270) the power requirement of the compression device (1) for the refrigerant circuit (23), - depending on the determined power requirement, shutting off or switching on or keeping shut off or keeping switched on (280) one or more of the shut-off single-flow compressors (47, 47a) or delivery flow channels (9, 9a, 9b).

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