Compressor unit and refrigeration system

Abstract

The invention refers to a compressor unit for use with a cooling unit, comprising a compressor housing provided with a motor housing portion with an electric drive motor arranged therein and the compressor housing portion provided with the refrigerant compressor, the compressor unit wherein the electric drive motor is a synchronous motor having a rotor provided with a lamination stack with a plurality of magnet receptacles in which permanent magnets are arranged and wherein the electric drive motor is driven by an inverter.

Description

[0001] COMPRESSOR UNIT AND REFRIGERATION SYSTEM

[0002] The invention refers to a compressor unit for use with a cooling unit, comprising a compressor housing provided with a motor housing portion with an electric drive motor arranged therein and the compressor housing portion provided with the refrigerant compressor.

[0003] Such compressor units are known from the prior art.

[0004] These compressor units are usually driven by asynchron motors.

[0005] It is therefore the object of the invention to provide a compressor unit as mentioned before with an energy optimized motor concept.

[0006] This object is solved by a compressor unit wherein the electric drive motor is a synchronous motor having a rotor provided with a lamination stack with a plurality of magnet receptacles in which permanent magnets are arranged and wherein the electric drive motor is driven by an inverter.

[0007] Such a concept enables an optimized driving of the refrigerant compressor due to the fact that on the one hand such a synchronous motor enables an energy efficient driving of the refrigerant compressor and the inverter enables to easily adjust the optimized rotational speed in an energy efficient manner.

[0008] In particular it is provided that the lamination stack is free of a squirrel cage.

[0009] Usually such a squirrel cage is used in order to start a synchronous motor without using an inverter but such a squirrel cage on the other hand has the disadvantage that the electric drive motor is less energy efficient as a synchronous motor without a squirrel cage. The synchronous motor according to the present invention can be efficiently designed by providing a lamination stack which is arranged between closing plates which closing plates are closing the magnet receptacles in axial direction of the motor so that the permanent magnets can be fixed in a safe manner within the lamination stack.

[0010] Further it is of advantage if the closing plates are connected by clamping pins extending through channels of the lamination stack so that the lamination stack together with the closing plates and the permanent magnets arranged in the magnet receptacles are forming one complete unit.

[0011] With respect to the design of the permanent magnets various solutions are possible.

[0012] One energy efficient design provides that the permanent magnets are permanent magnet plates having magnetic poles on their opposite flat surfaces, the extension of which being greater than the extension of other surfaces of such plates, which permanent magnet plates enable an efficient magnetic flux distribution through the rotor and through the stator.

[0013] According to one preferred solution the permanent magnet plates are oriented with their flat surfaces transverse to geometric radial directions with respect to the rotational axis, the radial directions intersecting the permanent magnet plates.

[0014] Such an orientation of the permanent magnet plates is similar to the concept of an IPM motor having the advantage that depending on the magnet sides an easy assembly of the rotor possible.

[0015] Further depending on the rotor size the magnets can withstand "high speed" without any retention system. Further the magnets can be magnetized after rotor assembly which makes rotor assembly easier.

[0016] Further such a concept enables to realize any number of poles of the rotor in order to adapt the rotor to the intended use.

[0017] Another advantageous solution provides that the permanent magnets are arranged in magnet receptacles enclosed in the lamination stack in geometric planes extending transverse to the rotational axis.

[0018] This design provides that the permanent magnets are surrounded by the lamination stack in the geometric planes extending transverse to the rotational axis so that in combination with the closing plates the permanent magnets can be easily sealed against aggressive substances within the refrigerant.

[0019] In addition the steel lamination around the permanent magnets reduces the risk of demagnetization.

[0020] In a preferred embodiment when considered in circumferential direction of the lamination stack subsequent permanent magnets have alternating poles on the sides opposite to the rotational axis, a design which enables an effective magnetic flux distribution around the rotor enabling optimized interaction with the stator.

[0021] One preferred solution provides that the permanent magnets are made of neodym based material, in particular NdFeB, a material which provides a high stability and efficiency of the electric drive motor.

[0022] Another advantageous solution provides that the permanent magnets are oriented with their flat surfaces parallel to a geometric radial direction to the rotational axis. In particular in case of permanent magnetic plates their flat surfaces having an extension greater than the other surfaces are extending parallel to the radial direction.

[0023] Such a rotor is a rotor according to a spoke design configuration which has the advantage that it allows a magnetic flux concentration giving the possibility of reaching high efficiency with acceptable motor dimensions.

[0024] It is of particular advantage if such a rotor has at least 6 poles or more in order to reach a good efficiency.

[0025] In particular in such a design subsequent permanent magnets in circumferential direction with respect to the rotational axis have flat surfaces facing each other with the same magnetic polarity in order to create a highly efficient flux distribution around the rotor.

[0026] In particular in such a design subsequent permanent magnets in circumferential direction around the rotational axis enclose a section of the lamination stack which guides magnetic flux lines of the subsequent magnets from their flat surfaces in radial direction towards the stator or from the stator in radial direction towards the flat surfaces.

[0027] Therefore the sections of the lamination stack provide a very efficient concentration of the magnetic flux lines.

[0028] In order to improve the flux distribution the magnetic receptacles of the lamination stack are open in radial direction.

[0029] Further the permanent magnets are fixed in the magnet receptacles of the lamination stack by fingers extending over a portion of the respective end face of the respective permanent magnet which respective end face is directed in radial direction outwards or inwards and extending transverse with respect to the rotational axis. The use of fingers for fixing the permanent magnets improves the management of the magnetic flux within the rotor and aids in optimizing the distribution of the magnetic field and improving the motor performance.

[0030] In particular these fingers can be designed very small so that in these fingers the magnetic field is saturated which reduces eddy currents induced in these fingers when they are exposed to change in magnetic fields which reduction of eddy currents has the consequence that the energy loss in the form of heat is reduced and therefore the motor is more efficient.

[0031] The efficiency of the electric motor can be further improved if the sections of the lamination stack are fixed by radial connections to a central portion of the lamination stack surrounding the drive shaft and being supported by the drive shaft.

[0032] These radial connections can be also designed to be saturated by the magnetic field in order to reduce eddy currents which are induced in a conductor material if it is exposed to changing magnetic field.

[0033] In particular the permanent magnets are made of ferrite based material because such ferrite based material enables to improve the efficiency with acceptable motor dimensions.

[0034] In particular these motors using permanent magnets of ferrite based material provide high magnetic properties and no demagnetization problem at low temperatures.

[0035] In particular the permanent magnets have a residual magnetic flux density of more than 440 mT and therefore enable high induction.

[0036] Further the permanent magnets shall have an intrinsic coersive force of more than 350 ka / m, preferable more 400 ka / m in a temperature range between -40°C to 150°C so that the ferrite magnets can withstand low temperatures which occur when used in an electric drive motor for a compressor unit, in particular a semi-hermetic compressor unit.

[0037] In order to avoid that the electric drive motor with the ferrite based permanent magnets is started at temperatures below -45°C or better below -40°C an advantageous solution provides heating of the compressor housing with a crankcase heater or oil heater and / or heating the stator of the electric drive motor by powering the stator before starting the compressor unit.

[0038] A further advantageous solution of the inventive concept provides that the compressor housing is provided with the housing portion on which the inverter is mounted.

[0039] Such mounting of the inverter of a housing portion of the compressor housing provides a compact unit for use in the field.

[0040] In particular it is of advantage if the housing portion is provided with a cooling passage through which cooled refrigerant enters the compressor housing for being compressed.

[0041] In such a concept the inverter can be easily cooled.

[0042] In particular the power electronic components of the inverter can be cooled in case they are arranged in direct contact with the housing portion.

[0043] In general the housing portion could be designed having the cooling passage through which cooled refrigerant flows to the refrigerant compressor.

[0044] A particular advantageous design of a semi-hermetic compressor uses the fact that the cooled refrigerant enters the housing portion, for first cooling the inverter and then leaves the housing portion for cooling the electric drive motor arranged in the motor housing portion.

[0045] This design has the advantage that the cooled refrigerant will be warmed up to a certain extend in the course of cooling the converter so that in particular in case of use of permanent magnets made of ferrite based material, which should not be exposed to temperatures below -45°C, the permanent magnets are warmed by refrigerant which has been warmed up.

[0046] Further according to an advantageous inventive concept the refrigerant after cooling the electric motor enters cylinder units of the compressor for being compressed therein.

[0047] According to a further advantageous solution according to which the electric drive motor is arranged in the motor housing portion the stator is mounted in the motor housing portion by means of supporting elements inserted into the motor housing portion which supporting elements on the one hand abut against an inner support surface of the motor housing portion and on the other hand surround the stator inserted into the supporting elements on its outer surface and support it spring-elastically relative to the inner support surface.

[0048] The advantage of the solution according to this concept of the invention is that the spring-elastic support of the stator relative to the stator receiving surface makes it possible to compensate for variations in the diameter of the motor receiving surface of the motor housing portion and at the same time to ensure that the stator is always arranged centered in the motor housing portion since the supporting element surrounding the stator and supporting it spring- elastically relative to the stator receiving surface act on opposite sides of the stator between the latter and the motor housing portion and thus keep the stator centered relative to the motor housing portion in the event of thermally induced and pressure induced diameter changes. This then has the advantage that the gap between the stator and the motor can be kept as small as possible and thus a high efficiency of the electric motor can be realized.

[0049] The spring-elastic supporting elements can be configured in very wide variety of manners.

[0050] For example, the supporting elements can be dimensioned such that they are in an elastically deformed state in all operating states of the motor housing portion occurring during operation of the compressor unit, such that in no operating state the spring-elastic bodies will enter the range of plastic deformation, which would result in the elastic properties of the spring-elastic bodies changing.

[0051] In particular it is advantageously provided that the supporting elements are arranged running around a stator and supporting the stator at a plurality of locations on opposite sides of the axis of rotation relative to the inner support surface of the motor housing portion in order to achieve a uniform spring elastic positioning of the stator acting on it from all sides.

[0052] In particular the supporting elements have elastic bodies arranged at defined angular intervals around the rotational axis so that they provide a high symmetrical support of the stator body.

[0053] One particular solution provides that the elastic bodies are arranged to enable a flow of refrigerant along the outer surface of the stator to enable a flow of refrigerant along the outer surface of the stator and with a flow component in direction of the axis of rotation for cooling the electric drive motor.

[0054] In particular the elastic bodies are positioned relative to one another on the stator receiving surface by a band material that positions them relative to one another and runs around the stator so that the band material provides a consistent and stable location of the elastic bodies. In case of using a band material it is of advantage if the elastic bodies are formed into the band material.

[0055] A particular favorable solution provides for the band material to be in the form of a ring-like clasp with open ends so that it can be easily deformed for assembly in the motor housing portion and thus can be inserted without material removal in particular in a motor housing portion formed from light material.

[0056] A particular simple realization of the spring-elastic bodies provide that they have flank regions running at an acute angle to the outer surface of the stator and / or the inner support surface between foot regions and support regions one of which abuts against the outer surface of the stator and the other of which abuts against the inner support surface.

[0057] According to a further embodiment the spring-elastic bodies are formed successively into a spring-elastic band material such that successive support regions abut against the outer surface of the stator or against the inner support surface and successive foot regions abut against the inner support surface or the outer surface of the stator.

[0058] It has proved to be advantageous if the spring-elastic bodies are located between edge regions arranged peripherally around the stator and the support regions and are connected to the edge regions by means of flank regions running at an acute angle to the outer side of the stator and / or to the inner support surface.

[0059] By means of these flank regions, in particular in addition to the flank regions connecting the support regions to the foot regions, this solution provides an advantageous elastic support of the support regions relative to the edge regions and, in addition, such flank regions allow the stator to be slid into the supporting elements already abutting on the stator receiving surface due to the fact of the flank regions as an insertion chamfer the stator being slid in parallel to the rotor axis of the electric motors.

[0060] Preferably in this solution on the one hand the support regions abut against the outer surface of the stator or the stator receiving surface and on the other hand the edge regions abut against the inner support surface or the outer side of the stator.

[0061] In particular the supporting elements, configured according to one or more of the features described above, allow the stator and housing sleeve to be decoupled wherein on the other hand the supporting elements can be mounted in the housing sleeve without material removal and then on the other hand the stator can be mounted by being slid in again without material removal in particular by means of the flank regions considered as insertion chamfers and can be removed by being pulled out, with a stator deforming the spring-elastic elements during the process of being slid in.

[0062] In particular the supporting elements described above are formed from a spring-elastic material, in particular spring steel.

[0063] In addition no details have yet been provided with regard to how the supporting elements are positioned in the motor housing portion.

[0064] For example an advantageous solution for achieving a defined relative position of the supporting elements provides that supporting elements arranged successively in direction of the rotor axis are positioned at a spacing from one another in the motor housing portion by a spacer element.

[0065] In particular the spacer element abuts against the inner support surface of the motor housing portion in the same way as the supporting elements and holds the elements at the spacing specified by the length of the spacer element in the direction of the motor axis. In order to be able to orient at least one of the supporting elements in respect of its position in the motor housing portion in a defined manner relative to the stator receiving surface it is preferably provided that at least one of the supporting elements is positioned in respect of its position in the motor housing portion by a step adjoining the stator receiving surface, more specifically in that the supporting element is positioned with at least one side abutting against the step.

[0066] Another advantageous solution provides that the overall compressor housing has a first cover unit and a second cover unit between which a tubular section extends, which comprises the motor housing portion in which the electric drive motor is provided and the compressor housing portion in which the refrigerant compressor is provided.

[0067] Such a design of the overall housing has the advantage that it is on one hand compact and simple to manufacture and enables easy assembly of the compressor unit and the electric drive motor.

[0068] Such a design is in particular of advantage in case of a semi-hermetic compressor unit because the tubular section provides a high stability with respect to the pressure within the overall housing.

[0069] It is of particular advantage if the tubular section has an approximately cylindrical shape.

[0070] Further it is of advantage if the compressor housing portion comprises a cylinder housing, in particular a cylinder housing integrally formed into the compressor housing portion, and a valve plate and a cylinder head cover arranged on the valve plate on a side opposite to said cylinder housing.

[0071] In order to reduce weight of the compressor it is of advantage if the tubular section comprising the cylinder housing and the end cover units arranged on opposite sides thereof are made of light metal in particular aluminum. Further it is of particular advantage if the valve plate and the cylinder head cover are made of steel because these parts are subject to high pressure and therefore it is of advantage to make these parts of steel in order to enable them to withstand the high pressure.

[0072] Another advantageous embodiment provides that the refrigerant compressor has a first compressor stage for compressing, to a medium pressure, refrigerant, in particular CO2, supplied at low pressure and a second compressor stage for compressing, to a high pressure the refrigerant in particular CO2, that has been compressed to a medium pressure and wherein in particular the refrigerant compressor unit comprises a medium-pressure outlet connected to the first compressor stage and a medium-pressure inlet connected to the second compressor stage.

[0073] In case of a semi-hermetic compressor design it is of advantage if the medium pressure inlet opens into a motor chamber of the electric drive motor for cooling the electric drive motor and compressed refrigerant enters the second compressor stage after having passed through the motor chamber.

[0074] In this case the electric drive motor within the motor chamber is cooled by refrigerant at medium pressure which then passes on from the motor chamber to the second compressor stage.

[0075] In order to reduce the pressure difference between the first compressor stage and the second compressor stage on one side and the drive chamber of the refrigerant compressor on the other side it is of advantage if a drive chamber of the refrigerant compressor from which the compressor stage are driven is held at medium pressure.

[0076] This can be easily resolved by connecting the drive chamber to the motor chamber via a connecting channel. In particular the refrigerant compressor according to this embodiment of the invention is a semi-hermetic compressor, wherein both, the electric drive motor and the refrigerant compressor, are arranged in an overall compressor housing of the semi-hermetic compressor.

[0077] In particular the refrigerant compressor is formed as a reciprocating compressor.

[0078] In this case the reciprocating compressor comprises a plurality of cylinder units of which at least one forms the first compressor stage and at least one forms the second compressor stage.

[0079] Since the volume to be compressed in the first compressor stage is greater than the volume compressed in the second compressor stage it is of advantage if at least two cylinder units form the first compressor stage, whereas for example it is sufficient to provide half of the number of cylinder units for the second compressor stage.

[0080] Further it is of advantage if the high-pressure connection on the refrigerant compressor unit is arranged on the cylinder head cover.

[0081] Further it is of advantage if a low-pressure connection of the refrigerant compressor unit is arranged on the cylinder head cover.

[0082] Further it is of advantage if a medium-pressure outlet of the refrigerant compressor unit is arranged on a cylinder head cover.

[0083] The fact that the pressure connections and inlets are arranged on the cylinder head cover has the advantage that the cylinder head - if it is made of steel - is easily able to withstand high pressure so that the tubular section of the overall housing it is only to be subject to medium-pressure. In particular it is provided that a medium-pressure inlet of the refrigerant compressor unit is arranged in the region of a motor housing portion.

[0084] Another advantageous embodiment provides that refrigerant that is supplied to the refrigerant compressor flows through the motor chamber and there is formed in the motor chamber on the bottom side a lubricant sump out of which lubricant is drawn off by suction by a suction-removal unit and is transferred to a lubricant bath in the motor chamber wherein there is provided on the bottom side of the motor chamber a receiving point that takes a form such that in particular in the event of tilting with a tilting tolerance range by the refrigerant compressor unit relative to a starting position the receiving point receives lubricant from the lubricant sump and supplies it to the suctionremoval unit.

[0085] In particular there is provided that the receiving point forms a well in relation to the area surrounding it on the bottom side.

[0086] One particular solution provides that the receiving point is arranged in the motor chamber such that, in the event of tilting of the refrigerant compressor unit an axis of rotation of a drive shaft is within a tilting tolerance range of ±15° relative to a horizontal orientation in the starting position, the lubricant sump extends as far as the receiving point and the lubricant from the lubricant sump enters the receiving point.

[0087] Further it is of advantage if the receiving point is arranged in a bottom region the motor chamber that runs from a supporting wall which separates the motor chamber from the drive chamber to below a region of the stator facing the supporting wall, and in particular runs for at most half of the extent of the stator in direction of rotation.

[0088] One advantageous solution provides that the receiving point is formed in a recess relative to a bottom face of the motor chamber so it can be easily incorporated into the tubular section of the housing. In particular it is provided that the receiving point is formed on a bottom body of the motor housing portion which bottom body of the motor housing portion is part of the tubular section of the overall housing.

[0089] In particular the receiving point is shaped into the bottom body.

[0090] The invention also relates to a refrigeration system, in particular a transport refrigeration system, comprising: a refrigerant circuit in which there is guided a total mass flow of refrigerant, a high-pressure-side heat exchanger arranged in the refrigerant circuit and cooling refrigerant compressed to a high pressure, an expansion member, which is arranged in the refrigerant circuit following on from the high-pressure-side heat exchanger and in the active state cools the total mass flow of the refrigerant by expansion and in so doing generates a principal mass flow of liquid refrigerant and an auxiliary mass flow of gaseous refrigerant, which enter an intermediate-pressure collector and are separated therein to the principal mass flow and the auxiliary mass flow, at least one cooling stage which expands the principal mass flow from the intermediate-pressure collector to low pressure in at least one cooling expansion member and in so doing makes refrigeration capacity available at a low-pressure-side heat exchanger, and a refrigerant compressor unit which compresses the principal mass flow from a low pressure to a high pressure, the refrigerant compressor unit has a first compressor stage for compressing to a medium pressure the refrigerant of the principal mass flow supplied at low pressure, and a second compressor stage for compressing to a high pressure, the refrigerant of the principal mass flow that has been compressed to a medium pressure, and the auxiliary mass flow from the intermediate-pressure collector enters the second compressor stage of the refrigerant compressor unit for compressing to a high pressure. This kind of refrigerant circuit is the preferred refrigerant circuit for optimized use of a two-stage compressor in order to efficiently compress refrigerant from low-pressure to high-pressure, in particular when using CO2 as refrigerant.

[0091] In such a refrigeration system it is of advantage if the first compressor stage of the refrigerant compressor unit is connected to a medium-pressure side heat exchanger which cools the principal mass flow that has been compressed to a medium pressure before said principal mass flow enters the second compressor stage.

[0092] In particular such a medium-pressure-side heat exchanger is an external heat exchanger arranged outside the refrigerant compressor unit.

[0093] As far as the expansion member is concerned it is of advantage if the expansion member expands the total mass flow to an intermediate pressure.

[0094] Further it is of advantage if the intermediate pressure corresponds substantially to the medium pressure so there is no adaption necessary between the medium pressure and the intermediate pressure.

[0095] In particular it is of advantage if the compressor unit is a compressor unit according to claim 44 to 55, in particular also comprising the features on which claim 44 is dependent.

[0096] Another advantageous refrigeration system provides, in particular a transport refrigeration system comprising a refrigerant circuit in which there is guided a total mass flow of refrigerant, a high-pressure-side heat exchanger arranged in the refrigerant circuit and cooling refrigerant compressed to high-pressure, an expansion member arranged in the refrigerant circuit following on from the high-pressure-side heat exchanger and expanding the total mass flow to low pressure in at least one cooling expansion member and in doing so make refrigerating capacity available at a low pressure-side heat exchanger and a refrigerant compressor unit according to at least one of claims 1 to 62, which compresses the total mass flow from low pressure to high pressure is provided.

[0097] This system design is in particular of advantage if CO2 is used as refrigerant.

[0098] In particular, advantageous embodiments of the invention comprise the combination of features as defined by the following consecutively numbered embodiments.

[0099] 1. Compressor unit (54) for use with a cooling unit (10), comprising a compressor housing (110) provided with a motor housing portion (118) with an electric drive motor (58) arranged therein and a compressor housing portion (150) provided with a refrigerant compressor (56), wherein the electric drive motor (58) is a synchronous motor having a rotor (138) provided with a lamination stack (240, 270) with a plurality of magnet receptacles (252, 262) in which permanent magnets (250, 260) are arranged and wherein the electric drive motor (58) is driven by an inverter (112).

[0100] 2. Compressor unit (54) according to embodiment 1, wherein the lamination stack (240, 270) is free of a squirrel cage.

[0101] 3. Compressor unit (54) according to embodiment 1 or 2, wherein the lamination stack (240, 270) is arranged between closing plates (242, 244, 292, 294) closing the magnet receptacles (252, 262) in axial direction of the rotor (128, 138').

[0102] 4. Compressor unit (54) according to embodiment 3, wherein the closing plates (242, 244, 292, 294) are connected by clamping pins (246, 296) extending through channels (248, 298) of the lamination stack (240, 270).

[0103] 5. Compressor unit (54) according to one of the preceding embodiments, wherein the permanent magnets (250, 260) are permanent magnet plates having magnetic poles (N, S) on their opposite flat surfaces (154, 156, 164, 166).

[0104] 6. Compressor unit (54) according to embodiment 5, wherein the permanent magnet plates (15) are oriented with their flat surfaces (254, 256) transverse to geometric radial directions (R) with respect to the rotational axis (184), the radial directions (R) intersecting the permanent magnet plates (250).

[0105] 7. Compressor unit (54) according to one of the preceding embodiments, wherein the permanent magnets (250) are arranged in magnet receptacles (252) enclosed by the lamination stack (240) in geometric planes extending transverse to the rotational axis (184).

[0106] 8. Compressor unit (54) according to embodiments 6 and 7, wherein in circumferential direction of the lamination stack (240) subsequent permanent magnets have alternating poles (N, S) on their sides opposite to the rotational axis (184).

[0107] 9. Compressor unit (54) according to one of embodiments 6 to 8, wherein the permanent magnets are made of Nd-based material.

[0108] 10. Compressor unit (54) according to one of embodiments 1 to 5, wherein the permanent magnets (260) are oriented with their flat surfaces (164, 166) parallel to a geometric radial direction (R) to the rotational axis (184).

[0109] 11. Compressor unit (54) according to embodiment 10, wherein subsequent permanent magnets (160) in circumferential direction with respect to the rotational axis (184) have flat-surfaces (264, 266) facing each other with the same magnetic polarity (N, S).

[0110] 12. Compressor unit (54) according to embodiment 10 or 11, wherein subsequent permanent magnets (260) in circumferential direction enclose a section (268) of the lamination stack (270) which guides magnetic flux lines (Fl) of the subsequent magnets (260) form their flat surfaces (264) in radial direction (R) towards the stator (132) or from the stator (132) in radial direction towards the flat surfaces (266).

[0111] 13. Compressor unit (54) according to one of embodiments 10 to 12, wherein the magnet receptacles (262) of the lamination stack (270) are open in radial direction (R).

[0112] 14. Compressor unit (54) according to embodiment 13, wherein the permanent magnets (260) are fixed in the magnet receptacles (262) of the lamination stack (270) by fingers (284, 286) extending over a portion of the respective end face (286, 288) of the respective permanent magnet (260) extending transverse to the radial direction.

[0113] 15. Compressor unit (54) according to one of embodiments 10 to 14, wherein the sections (268) of the lamination stack (270) are fixed by radial connections (278) to a central portion (276) of the lamination stack (270) surrounding the drive shaft (142) and being supported by the drive shaft (142).

[0114] 16. Compressor unit (54) according to one of embodiments 10 to 15, wherein the permanent magnets (260) are made of ferrite based material.

[0115] 17. Compressor unit (54) according to embodiment 16, wherein the permanent magnets (260) have a residual magnetic flux density (Br) of more than 440mT.

[0116] 18. Compressor unit (54) according to embodiment 16 or 17, wherein the permanent magnets have an intrinsic coercive force (Hcf) of more than 350 ka / m, preferably more than 400 ka / m, in a temperature range between -40°C to + 150°C. 19. Compressor unit (54) according to one of the preceding embodiments, wherein the compressor housing (110) is provided with a housing portion (108) on which the inverter (112) is mounted.

[0117] 20. Compressor unit (54) according to embodiment 19, wherein the housing portion (108) is provided with a cooling passage (106) through which cooled refrigerant enters the compressor housing (110) for being compressed.

[0118] 21. Compressor unit (54) according to embodiment 20, wherein power electronic components (114) of the inverter (112) are arranged in direct contact with the housing portion (108).

[0119] 22. Compressor unit (54) according one of embodiments 19 to 21, wherein cooled refrigerant entering housing portion (108) leaves the housing portion (108) for cooling the electric drive motor (58) arranged in motor housing portion (118).

[0120] 23. Compressor unit (54) according to one of the preceding embodiments, wherein refrigerant after cooling the electric drive motor (58) enters cylinder units (154a, 154b, 414a, 414b, 444) of the compressor (56) for being compressed therein.

[0121] 24. Compressor unit (54) according to one of the preceding embodiments, wherein with the electric drive motor (58) arranged in the motor housing portion (118) the stator (132) is mounted in the motor housing portion (118) by means of supporting elements (134) inserted into the motor housing portion (118), which supporting elements (134) on the one hand abut against an inner support surface (136) of the motor housing portion (118) and on the other hand surround the stator (138) inserted into the supporting elements (134) on its outer surface (302) and support it spring-elastically relative to the inner support surface (136). 25. Compressor unit (54) according to embodiment 24, wherein the supporting elements (134) have spring-elastic bodies (304) which are dimensioned such that they are in an elastically deformed state in all operating states of the motor housing portion (118) occurring during operation of the compressor unit (54).

[0122] 26. Compressor unit (54) according to embodiment 24 or 25, wherein the supporting elements (134) are arranged running around the stator (132) and supporting the stator (132) at a plurality of locations on opposite sides of the axis of rotation (184) relative to the inner support surface (136) of the motor housing portion (118).

[0123] 27. Compressor unit (54) according to one of embodiments 24 to 26, wherein the supporting elements (134) have elastic bodies (304) arranged at defined angular intervals around the rotational axis (184).

[0124] 28. Compressor unit (54) according to embodiment 26 or 27, wherein the elastic bodies (304) are arranged to enable a flow of refrigerant along the outer surface (302) of the stator (132) and with a flow component in direction of the axis of rotation (184) for cooling the electric drive motor (58).

[0125] 29. Compressor unit (54) according to one of embodiments 26 to 28, wherein the elastic bodies (304) are positioned relative to one another by a band material (310) positioning them relative to one another and running around the stator (132).

[0126] 30. Compressor unit (54) according to one of embodiments 27 to 29, wherein the elastic bodies (304) are formed into the band material (310).

[0127] 31. Compressor unit (54) according to one of embodiments 27 to 30, wherein the band material (310) is in the form of a ring-like clasp with open ends (312). 32. Compressor unit (54) according to one of embodiments 27 to 31, wherein the spring-elastic bodies (304) have flank regions (324, 326) running at an acute angle to the outer surface (302) of the stator (132) and / or to the inner support surface (136) between foot regions and support regions, one of which abuts against the outer surface (302) of the stator (132) and the other of which abuts against the inner support surface (136).

[0128] 33. Compressor unit (54) according to one of embodiments 27 to 32, wherein the spring-elastic bodies (304) are successively formed into a spring-elastic band material (310) such that successive support regions abut against an outer surface (302) of the stator (138) or against the inner support surface (136) and successive foot regions abut against the inner support surface (136) or the outer surface (302) of the stator (132).

[0129] 34. Compressor unit (54) according to one of embodiments 27 to 32, wherein the spring-elastic bodies (304) are located between edge regions (314, 316) arranged peripherally around the stator (132), and the support regions (322) are connected to the edge regions (314, 316) by means of flank regions (324, 326) running at an acute angle to the outer side of the stator (132) and / or to the inner support surface (136).

[0130] 35. Compressor unit (54) according to embodiment 34, wherein, on the one hand, the support regions (322) abut against the outer surface (302) of the stator (132) or the inner support surface (136) and, on the other hand, the edge regions (314, 316) abut against the inner support surface (136) or the outer surface (302) of the stator (132).

[0131] 36. Compressor unit (54) according to one of embodiments 24 to 35, wherein the supporting elements (134) are formed from a spring-elastic material, in particular spring steel.

[0132] 37. Compressor unit (54) according to one of embodiments 24 to 36, wherein supporting elements (134) arranged successively in the direction of the rotational axis (184) are positioned spaced apart from one another in the motor housing portion (118) by a spacer element (344).

[0133] 38. Compressor unit (54) according to embodiment 37, wherein one of the supporting elements (134) is positioned in respect of its position in the motor housing portion (118) by a step adjoining the inner support surface (136).

[0134] 39. Compressor unit (54) according to one of the preceding embodiments, wherein the overall compressor housing (110) has a first cover unit (122) and a second cover unit (124), between which a tubular section (120) extends, which comprises the motor housing portion (118) in which the electric drive motor (58) is provided and the compressor housing portion (150) in which the refrigerant compressor (56) is provided.

[0135] 40. Compressor unit (54) according to embodiment 39, wherein the tubular section (120) has an approximately cylindrical, shape.

[0136] 41. Compressor unit (54) according to embodiment 39 or 40, wherein the compressor housing portion (150) comprises a cylinder housing (156) with a valve plate (162) and a cylinder head cover (172) arranged on said valve plate (162).

[0137] 42. Compressor unit (54) according to one of embodiments 39 to 41, wherein the tubular section (120) comprising the cylinder housing (156) and the end cover units (122, 124) arranged on opposite sides thereof are made of light metal, in particular aluminum.

[0138] 43. Compressor unit (54) according to embodiment 42, wherein the valve plate (162) and the cylinder head cover (172) are made of steel.

[0139] 44. Compressor unit (54') according to one of the preceding embodiments, wherein the refrigerant compressor (56') has a first compressor stage (412) for compressing, to a medium pressure, refrigerant, in particular CO2, supplied at low pressure, and a second compressor stage (442) for compressing, to a high pressure (PH), the refrigerant, in particular CO2, that has been compressed to a medium pressure (PM), and wherein in particular the refrigerant compressor unit comprises a medium-pressure outlet (422) connected to the first compressor stage (412) and a medium-pressure inlet (428) connected to the second compressor stage (442).

[0140] 45. Compressor unit (54') according to embodiment 44, wherein the mediumpressure inlet (428) opens out into a motor chamber (116) of the electric drive motor (58) for cooling the electric drive motor (58), and compressed refrigerant enters the second compressor stage (442) after having passed through the motor chamber (116).

[0141] 46. Compressor unit (54') according to embodiment 44 or 45, wherein a drive chamber (146) of the refrigerant compressor (56'), from which the compressor stages (412, 442) are driven, is held at medium pressure (PM).

[0142] 47. Compressor unit (54') according to embodiment 46, wherein the drive chamber (146) is connected to the motor chamber (116) via a connecting channel.

[0143] 48. Compressor unit (54') according to one of embodiments 44 to 47, wherein the refrigerant compressor unit (54') is formed as a semi-hermetic compressor, wherein both, the electric drive motor (58) and the refrigerant compressor (56'), are arranged in an overall compressor housing (110) of the semi-hermetic compressor.

[0144] 49. Compressor unit (54') according to one of embodiments 44 to 48, wherein the refrigerant compressor (56') is formed as a reciprocating compressor.

[0145] 50. Compressor unit (54') according to embodiment 49, wherein the reciprocating compressor has a plurality of cylinder units (414, 444), of which at least one forms the first compressor stage (412) and at least one forms the second compressor stage (442).

[0146] 51. Compressor unit (54') according to one of embodiments 44 to 50, wherein at least two cylinder units (414a, 414b) form the first compressor stage (412).

[0147] 52. Compressor unit (54') according to one of embodiments 44 to 51, wherein a high-pressure connection (372) of the refrigerant compressor unit (54') is arranged on the cylinder head cover (172').

[0148] 53. Compressor unit (54') according to one of embodiments 44 to 52, wherein a low-pressure connection of the refrigerant compressor unit (54') is arranged on the cylinder head cover (172').

[0149] 54. Compressor unit (54') according to one of embodiments 44 to 53, wherein a medium-pressure outlet (422) of the refrigerant compressor unit (54') is arranged on the cylinder head cover (172').

[0150] 55. Compressor unit (54') according to one of embodiments 44 to 54, wherein a medium-pressure inlet (428) of the refrigerant compressor unit (54') is arranged in the region of a motor housing portion (118)

[0151] 56. Compressor unit (54), according to one of the preceding embodiments, wherein refrigerant that is supplied to the refrigerant compressor (56) flows through the motor chamber (116) and there is formed in the motor chamber (116), on the bottom side, a lubricant sump (222) out of which lubricant is drawn off by suction by a suction-removal unit (210) and is transferred to a lubricant bath (194) in the motor chamber (116), wherein there is provided on the bottom side of the motor chamber (116) a receiving point (224) that takes a form such that, in particular in the event of tilting within a tilting tolerance range by the refrigerant compressor unit (54) relative to a starting position, the receiving point (224) receives lubricant from the lubricant sump (222) and supplies it to the suction-removal unit (210). 57. Compressor unit (54) according to embodiment 56, wherein the receiving point (224) forms a well in relation to the area surrounding it on the bottom side.

[0152] 58. Compressor unit (54) according to embodiment 56 or 57, wherein the receiving point (224) is arranged in the motor chamber (116) such that, in the event of tilting of the refrigerant compressor unit (54), an axis of rotation (184) of a drive shaft (182) is within a tilting tolerance range of ±15° relative to a horizontal orientation in the starting position, the lubricant sump (222) extends as far as the receiving point (224) and lubricant from the lubricant sump (222) enters the receiving point (224).

[0153] 59. Compressor unit (54) according to one of embodiments 56 to 58, wherein the receiving point (222) is arranged in a bottom region of the motor chamber (116) that runs from a supporting wall (140), which separates the motor chamber (116) from the drive chamber (116) to below a region of the stator (132) facing the supporting wall (140), and in particular runs for at most half of the extent of the stator (132) in direction of rotation (184).

[0154] 60. Compressor unit (54) according to one of embodiments 56 to 59, wherein the receiving point (224) is formed in a recess relative to a bottom face of the motor chamber (116).

[0155] 61. Compressor unit (54) according to embodiment 60, wherein the receiving point (224) is formed on a bottom body of the motor housing portion (118).

[0156] 62. Compressor unit according to embodiment 61, wherein the receiving point (224) is shaped into the bottom body.

[0157] 63. A refrigeration system (60), in particular a transport refrigeration system, comprising: a refrigerant circuit (370) in which there is guided a total mass flow (TMF) of refrigerant, a high-pressure-side heat exchanger (62) arranged in the refrigerant circuit (370) and cooling refrigerant compressed to a high pressure (HP), an expansion member (376), which is arranged in the refrigerant circuit (370) following on from the high-pressure-side heat exchanger (62) and in the active state cools the total mass flow (TMF) of the refrigerant by expansion and in so doing generates a principal mass flow (PMF) of liquid refrigerant and an auxiliary mass flow (AMF) of gaseous refrigerant, which enter an intermediate-pressure collector (382) and are separated therein into the principal mass flow (PMF) and the auxiliary mass flow (AMF), at least one cooling stage (392) which expands the principal mass flow (PMF) from the intermediate-pressure collector to low pressure (LP) in at least one cooling expansion member (394) and in so doing makes refrigerating capacity available at a low-pressure-side heat exchanger (34), and a refrigerant compressor unit (54') which compresses the principal mass flow (PMF) from a low pressure (LP) to a high pressure (HP), the refrigerant compressor unit (54') has a first compressor stage 412) for compressing to a medium pressure (MP) the refrigerant of the principal mass flow (PMF) supplied at low pressure (LP), and a second compressor stage (424) for compressing, to a high pressure (HP), the refrigerant of the principal mass flow (PMF) that has been compressed to a medium pressure (MP), and the auxiliary mass flow (AMF) from the intermediate-pressure collector (382) enters the second compressor stage (424) of the refrigerant compressor unit (54') for compressing to a high pressure (HP).

[0158] 64. A refrigerant system according to embodiment 63, wherein the first compressor stage (412) of the refrigerant compressor unit (54') is connected to a medium-pressure-side heat exchanger (424), which cools the principal mass flow (PMF) that has been compressed to a medium pressure (MP) before said principal mass flow (PMF) enters the second compressor stage (424).

[0159] 65. A refrigeration system according to embodiment 64, wherein the mediumpressure-side heat exchanger (424) is an external heat exchanger arranged outside the refrigerant compressor unit (54'). 66. A refrigerant system according to one of embodiments 63 to 65, wherein the expansion member (376) expands the total mass flow (TMF) to an intermediate pressure (IP).

[0160] 67. A refrigeration system according to embodiment 66, wherein the intermediate pressure (IP) corresponds substantially to the medium pressure (MP).

[0161] 68. A refrigeration system according to one of embodiments 63 to 67, wherein the compressor unit (54') is a compressor unit according to claims 44 to 55 in particular also comprising the features on which claim 44 is dependent.

[0162] 69. A refrigeration system, in particular a transport refrigeration system (60) comprising a refrigerant circuit (70) in which there is guided a total mass flow (TMF) of refrigerant, a high-pressure-side heat exchanger (62) arranged in the refrigerant circuit (70) and cooling refrigerant compressed to high-pressure (HP), an expansion member (94) arranged in the refrigerant circuit (70) following on from the high-pressure-side heat exchanger (62) and expanding the total mass flow (TMF) to low pressure (LP) in at least one cooling expansion member (94) and in doing so make refrigerating capacity available at a low pressure-side heat exchanger (34) and a refrigerant compressor unit (54) according to at least one of claims 1 to 62, which compresses the total mass flow from low pressure (LP) to high pressure (HP).

[0163] Further features and advantages of the invention are subject matter of the following detailed specification as well as the graphic representation of a number of exemplary embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0164] Fig. 1 shows a schematic illustration of a cooling unit, in particular formed as transport cooling unit with a refrigeration system according to the invention;

[0165] Fig. 2 shows a refrigeration circuit with a first embodiment of a compressor unit according to the present invention in cross section;

[0166] Fig. 3 shows an enlarged representation of the first embodiment of the compressor unit in cross section;

[0167] Fig. 4 shows a sectional view of a lamination stack of a rotor of a first embodiment of the electric motor;

[0168] Fig. 5 shows a front view according to arrow 5 in Fig. 4 on the lamination stack according to Fig. 4;

[0169] Fig. 6 shows a cross section along lines 6-6 through the lamination stack according to a first stator design;

[0170] Fig. 7 show a cross section according to lines 6-6 in Fig. 4 according to a second stator design;

[0171] Fig. 8 shows a lamination stack according to Fig. 4 of a second embodiment of the electric drive motor;

[0172] Fig. 9 shows a cross section according to lines 9-9 in Fig. 8;

[0173] Fig. 10 shows a sectional view of the cross section in Fig. 9 together with a sectional view of the corresponding stator; Fig. 11 shows an enlarged representation of a bottom area of the compressor housing portion with a lower part of the stator;

[0174] Fig. 12 shows a perspective view of an embodiment of a support element for supporting the stator according to Fig. 11;

[0175] Fig. 13 shows a sectional view of a cross section along line 13-13 in Fig. 11;

[0176] Fig. 14 shows a schematic representation of a second refrigerant circuit with a sectional view of a second exemplary embodiment of the refrigerant compressor unit;

[0177] Fig. 15 shows an enlarged view of the second embodiment of the refrigerant compressor unit.

[0178] DETAILED DESCRIPTION OF THE INVENTION

[0179] A cooling unit denoted as a whole by 10 comprises a thermally insulated housing 12, which encloses an interior 14, in which temperature-sensitive goods 16 or temperature-sensitive cargo 16 may be stored, the temperaturesensitive goods 16 or the temperature-sensitive cargo 16 being surrounded by a gaseous medium 18, in particular air, which is held at a defined temperature level in order to keep the temperature-sensitive cargo 16 or the temperaturesensitive goods 16 within a specified temperature range.

[0180] The cooling unit 10 is preferably formed as a transportable cooling unit, for example as a structure for a lorry or a freight wagon or as a conventional transport container or reefer for transporting temperature-sensitive cargo 16 either by lorry or train or ship.

[0181] In order to be able to maintain a defined or pre-specified temperature range for the cargo 16, a circulation flow 22 of the gaseous medium 18 is circulated in the interior 14, wherein, starting from a temperature-control unit 24, an inlet flow 26 enters the interior 14, passes through it, and enters the temperature-control unit 24 again as an outlet flow 28.

[0182] The circulation flow 22 is generated here by a fan unit 32, which is arranged in the temperature-control unit 24 and the circulation flow is held at the desired temperature by an internal heat exchanger 34, which is arranged in temperature-control unit 24.

[0183] In this case, the inlet flow 26 preferably exits from the temperature-control unit 24 in a region close to a top wall 36 or a bottom wall 38 of the insulated housing 12, and the circulation flow 22 is preferably guided close to the bottom wall 38 or the top wall 36 of the insulated housing 12 back to the temperature-control unit 24, and in so doing forms the outlet flow 28 passing back to the temperature-control unit 24.

[0184] However, it is also possible to reverse the direction of the circulation flow as indicated in Fig. 1 by dashed lines.

[0185] In particular, the temperature-control unit 24 is arranged close to the top wall 36 of the insulated housing 12 and for example close to a front wall 48 or close to a rear wall 48 of the housing.

[0186] An equipment unit 52 comprising a refrigerant compressor unit 54 with a refrigerant compressor 56 and an electric drive motor 58 is arranged preferably close to the temperature-control unit 24 on the thermally insulated housing 12, wherein the equipment unit 52 preferably also additionally comprises a first external heat exchanger 62 and an external fan unit 64, which for example generates an airflow 66 from ambient air, which airflow passes through the first external heat exchanger 62.

[0187] As shown in Fig 2, the refrigerant compressor unit 54, the inner heat exchanger 34, and the first external heat exchanger 62 are arranged in a refrigerant circuit of a refrigeration system 60 integrated in the cooling unit, said first embodiment of a refrigerant circuit being denoted as a whole by 70.

[0188] The refrigerant circuit 70 is connected to a high-pressure connection 72 of the refrigerant compressor unit 54, starting from which high-pressure connection a supply line 74 leads to the first external heat exchanger 62, which heat exchanger 62 cools a total mass flow TMF of refrigerant, in the present case compressed to high pressure by the refrigerant compressor 56, the refrigerant being present.

[0189] If for example C02 is used as refrigerant, the refrigerant compressed to high pressure is for example in a trans-critical state.

[0190] In this case, the refrigerant may be cooled in the first external high-pressure- side heat exchanger unit 62 either by ambient air, or also by contact with a heat-absorbing medium of any kind, for example also cooling water.

[0191] The total mass flow TMF of liquid refrigerant, starting from the heat exchanger unit 62 is supplied to a cooling stage 92, which comprises a cooling expansion member 94, which expands the total mass flow TMF to a low pressure PN by expansion, and, starting from here, the total mass flow TMF enters the internal low-pressure-side heat exchanger 34, in which, due to the fact that refrigeration capacity has been made available, it is able to absorb heat from the circulation flow 22 in the interior 18 of the cooling unit 10.

[0192] The total mass flow TMF heated in the heat exchanger 34 then enters a first embodiment of refrigerant compressor unit 54 at low pressure LP via a low- pressure connection 102.

[0193] Low pressure connection 102 is followed by a channel 104, arranged for example in a compressor housing 110 and connected to a cooling passage 106 of housing portion 108 on which an inverter 112 is mounted, the power electronics 114 of which is in direct thermal contact with the housing portion 108 in order to be cooled by the cooling passage 106.

[0194] The total mass flow TMF of refrigerant is warmed up in cooling passage 106 and exits from cooling passage 106 into a motor chamber 116 arranged within a motor housing portion 118 of compressor housing 110 for cooling the electric drive motor 58 arranged in motor chamber 116.

[0195] The compressor housing 110 comprises a tubular section 120 extending from an end cover unit 122 comprising housing portion 108 with cooling passage 106 and with the inverter 112 mounted thereon, to an end cover unit 124 arranged opposite to end cover unit 122 so that the tubular section 120 is closed on opposite sides by end cover units 122 and 124.

[0196] Preferably tubular section 120 and end cover units 122 and 124 are made of light metal, in particular aluminum.

[0197] Motor chamber 116 is extending within motor housing portion 118 from end cover unit 122 in direction towards end cover unit 124 with the electric drive motor 58 arranged therein.

[0198] The electric drive motor 58 comprises a stator 132 fixed by stator supporting elements 134a, 134b which are supported by an inner support surface 136 of the motor housing portion 118 of tubular section 120 of the compressor housing 110 surrounding motor chamber 116.

[0199] Within rotor 138 is arranged on a drive shaft 142 supporting rotor 138 and extending from rotor 138 through a supporting wall 140 formed for example integrally within tubular section 120 and separating motor chamber 116 from a cylinder drive chamber 146.

[0200] Supporting wall 140 comprises a bearing unit 144 supporting the drive shaft

[0201] 142 which extends from rotor 138 through bearing unit 144 into cylinder drive chamber 146 of refrigerant compressor 56 arranged on a side of support wall 140 opposite to the motor chamber 116.

[0202] Refrigerant compressor 56 of refrigerant compressor unit 54, as shown in Fig. 2 and 3, comprises cylinder drives 152a, 152b, for example eccentric drives, which are arranged and driven be a section of drive shaft 142 extending within motor chamber 116 for driving cylinder units 154a, 154b.

[0203] Cylinder units 154a, 154b comprise a cylinder housing 156 integrally formed into compressor housing portion 150 of compressor housing 110 and provided with cylinder bores 158a, 158b in which pistons 162a, b are moveable in a reciprocating manner driven by cylinder drives 152a, 152b.

[0204] Cylinder bores 158a, 158b of cylinder housing 156 on their upper sides are closed by a valve plate 162 covering cylinder bores 158a, 158b and closing them off in order to establish compression chambers 164a, 164b within said cylinder bores 158a, 158b.

[0205] In addition, valve plate 162 is provided with at least one inlet opening 166a, 166b and at least one outlet opening 168a, 168b for each compression chamber 164a, 164b.

[0206] Each inlet opening 166a, 166b and each outlet opening 166a, 166b is provided with a respective valve, not shown in Fig. 2 and 3.

[0207] A cylinder head cover 172 arranged on valve plate 162 on a side opposite to cylinder housing 156 comprises at least one inlet chamber 174 arranged in connection with inlet openings 166a, 166b and at least one outlet chamber (not shown) arranged in connection with outlet openings 168a, 168b in valve plate 162.

[0208] The at least on outlet chamber is connected to high pressure connection 72 and the at least one inlet chamber 174 is connected via channel 178 to motor chamber 116 close to supporting wall 140 so as to draw refrigerant out of motor chamber 116 after having cooled electric drive motor 58.

[0209] Valve plate 162 and cylinder head cover 172 are preferably made of steel in order to enable them to withstand high pressure, in particular in case CO2 is used as refrigerant.

[0210] It is of particular advantage if drive shaft 142 is not only supported in bearing 144 of supporting wall 140 but also in a bearing unit 182 arranged on end cover 124, in particular as an integral part thereof.

[0211] This enables to support drive shaft 142 on opposite sides of cylinder drives 152a, 152b in order to properly guide drive shaft 142 for rotation about an axis of rotation 184 in motor chamber 116.

[0212] For supporting rotor 138 in motor chamber 116 it is sufficient to support drive shaft 142 by bearing unit 144 so that drive shaft 142 extends from bearing unit 144 into rotor 138 and has a non supported end facing end cover 122 so that the total mass flow TMF of refrigerant leaving cooling passage 106 and entering motor chamber 116 can easily be distributed in motor chamber 116 in order to provide effective cooling of electric drive motor 58.

[0213] Cooling of electric drive motor 58 is optimized if part of the total mass flow TMF when exiting from cooling passage 106 and flowing in direction of channel 178 for entering inlet chamber 116 passes through a gap 186 between stator 132 and rotor 138 and part of the total mass flow TMF passes through stator carrier 134.

[0214] Further in the first embodiment there is provided in the end cover 124 a lubricant supply unit 190 (Fig. 3) that, by means of a pumping unit 192 arranged for example on the end cover 124 and associated in particular with the bearing unit 182, moves lubricant out of a lubricant bath 194 formed by lubricant collected on the bottom side of the drive chamber 146, via a filter 196 arranged therein and a receiving duct 198 running in end cover 22, and into a drive shaft duct 202 that runs within drive shaft 142, preferably coaxially with the axis of rotation 184, wherein the drive shaft duct 202 runs from the bearing unit 182 as far as the bearing unit 144, and a transverse duct 204 leads from the drive shaft duct 202 in the region of the bearing unit 144 arranged within supporting wall 140, to a receptacle 206 which is provided in the bearing unit 144 and which runs around drive shaft 142 and from which in turn a conveying duct 208 of a suction-removal unit 210 runs through supporting wall 140 and through a supply conduit 212 that adjoins the conveying duct 208 and runs as far as an ejector 214.

[0215] Further, and where necessary, the suction-removal unit 210 comprises a nonreturn valve 216 that is connected on the suction side of the ejector 214 and arranged in the supporting wall 140, and a suction duct 218 that is guided from the nonreturn valve 216 into the motor chamber 116, such that the suction-removal unit 210 is able to draw off lubricant by suction from the motor chamber 116, during which this lubricant flows through the nonreturn valve 216 and is supplied from the ejector 214 to the lubricant bath 194 in drive chamber 146 as described for example in DE 2 250 947.

[0216] In this arrangement, the suction duct 218 may be formed by a pipe piece or - as illustrated - by a bore in the bottom side.

[0217] As mentioned above, refrigerant flows through the motor chamber 116 and - because the refrigerant carries lubricant with it, in particular when it comes from the low-pressure stage - as the lubricant flows through the motor chamber 116, it settles therein on the bottom side of the motor chamber 116 in the form of a lubricant sump 222, and with the aid of the suction-removal unit 210 lubricant from the lubricant sump 222 is transferred to the lubricant bath 194 of the drive chamber 146.

[0218] For the purpose of receiving the lubricant from the lubricant sump 222, there is provided on the bottom side of the motor chamber 116 a receiving point 224 which takes a form such that it feeds lubricant out of the lubricant sump 222 and into the suction-removal unit 210, in particular the suction duct 218 thereof.

[0219] In the illustrated exemplary embodiment, the position of the receiving point 224 is selected such that the refrigerant compressor unit 10 can be operated even in a condition in which the axis of rotation 184 of the drive shaft 142 does not run horizontally but may run at a tilt of ±15° in relation to the horizontal orientation.

[0220] The result of this is that the receiving point 224 is formed in a recess 226 relative to a bottom face of the motor chamber 116, and moreover that the receiving point 224 is positioned in a bottom region, which is adjacent to the supporting wall 140 and extends from the supporting wall 140 to below a region of the stator 132 that is arranged facing the supporting wall 140, wherein the region comprises at most half of the extent of the stator 132 in longitudinal direction.

[0221] According to the first embodiment of the electric drive motor 58 the rotor 138 comprises - as shown in Fig. 4 and 5 - a lamination stack 240 which is provided on both sides with closing plates 242, 244 which are subject to clamping forces exerted by clamping pins 246 extending through channels 248 in the lamination stack 240 and acting on closing plates 242, 244 in order to keep the laminations of the lamination stack 240 squeezed between closing plates 242, 244,

[0222] As shown in Fig. 6 an even number of permanent magnet plates 250 is arranged in magnet receptacles 252 arranged within lamination stack 240 having N and S magnetic poles on their opposite outer and inner flat surfaces 254, 256 (Fig. 5, 6).

[0223] Permanent magnet plates 250 of the plurality of permanent magnet plates are arranged in the magnet receptacles 252 such that they extend with their flat surfaces 254, 256 in circumferential direction or transverse to a geometric radial direction R of the rotational axis 184 of drive shaft 142 intersecting magnet plates 250 whereby subsequent permanent magnet plates 250 have alternating polarity on their outer flat surfaces 254 such that in circumferential direction an outer side of lamination stack 240 a polarity N is followed by a polarity S and vice versa on (Fig. 5, 6).

[0224] In addition, the magnet receptacles 252 are surrounded on all sides by lamination stack 240 in planes extending transverse to rotational axis 184 closed by closing plates 242, 244 in order to keep the permanent magnet plates 250 fixed in lamination stack 240 (Fig. 4).

[0225] However, the number of permanent magnet plates 250 can vary as shown for example in Fig. 6 and Fig. 7.

[0226] In this type of rotor 138 the permanent magnet plates 250 use Nd based material in particular NdFeB, as magnetic material.

[0227] The rotor 138 according to the first embodiment of the electric drive motor 58 is not provided with a squirrel cage.

[0228] According to the present invention the electric drive motor 58 with rotor 138 is a synchronous motor driven by inverter 112 which according to the first embodiment is mounted on the compressor housing 110, in particular on end cover 122 and cooled by expanded refrigerant which after cooling inverter 112 is cooling electric drive motor 58.

[0229] According to a second embodiment of the electric drive motor 58' of refrigerant compressor unit 54 an alternative version of rotor 138', shown in Fig. 8 and 9, is provided with a lamination stack 270 having permanent magnet plates 260 arranged in magnet receptacles 262 extending parallel to an intersecting geometric radial direction R of rotational axis 184 of drive shaft 142 with their opposite flat surfaces 264, 266 being arranged parallel to radial directions and being provided with opposite magnetic poles N, S on their opposite flat surfaces 264, 266.

[0230] In circumferential direction subsequent permanent magnet plates 260 have the same polarity on those flat surfaces 264, 266 which are facing each other but which are separated from each other by a section 268 of the lamination stack 270 as shown in Fig. 9.

[0231] This has the consequence that - as shown in Fig. 9 - the same magnetic flux lines Fit are extending transverse to the respective flat surfaces 264 from a first pair of flat surfaces 264 facing each other enter into the respective section 268 of the lamination stack 270 arranged between the respective pair of surfaces 264 and therein the flux lines turn to radial direction Fir in order to form an outer field area circumscribing an outer end portion 288 of the respective permanent magnet plates 260 and thereby flux lines Fir extend through poles 272 and then extend as flux lines FIc through pole carriers 274 of lamination stack 270 of the stator 132 and return to the next section 268 as flux lines Fir in radial direction and then turn as flux lines Fit towards the surface 266, 266 of the same respective permanent magnet plate 260 having opposite polarity.

[0232] The sections 268 of lamination stack 270 are fixed to a central portion 276 of the lamination stack 270 surrounding the drive shaft 142 by small radial connections 278 designed to be saturated by the magnetic flux of the permanent magnets 260 in order to reduce eddy current losses due to fewer induction of eddy currents due to changing magnetic fields (Fig. 10).

[0233] For the same reason permanent magnet plates 260 are held in the magnet receptacles 262 by small or thin fingers 282 and 284 extending from the respective sections 268 over part of end faces 286, 288 extending between the surfaces 264 and 266 in circumferential direction of the respective permanent magnet plates 260 in order to provide proper radial positioning of the permanent magnet plates 260 within magnet receptacles 262 of the lamination stack 270 (Fig. 10).

[0234] In order to optimize the flow of the magnetic flux through sections 268 fingers 282 and 284 with their facing each other are spaced from each other in order to leave the magnet receptacles 262 open in radial directions.

[0235] Lamination stack 270 of rotor 138' is further provided with closing plates 292, 294 closing magnet receptacle 262 in axial direction and keeping the lamination stack 270 squeezed therebetween whereas closing plates 292, 294 are subject to clamping forces exerted by clamping pins 296 extending through channels 298 arranged in the middle of sections 268 of lamination stack 240' in order not to disturb the magnetic flux lines Fir in sections 268 (Fig. 8, 9).

[0236] The permanent magnet plates 260 are made of ferrite based magnetic material, for example ferrite material having an intrinsic coercitive force Hcj of at least 350kA / m preferably at least 400kA / m in a temperature range from - 40°C to +150°C and in particular a residual magnetic flux density Br of at least 440mT.

[0237] According to the second embodiment of the electric motor 58' the rotor 138' is not provided with a squirrel cage.

[0238] The electric drive motor 58 being provided with rotor 138' is also a synchronous motor driven by inverter 112 mounted for example on housing portion 108.

[0239] The stator 132 according to the first and second embodiment is preferably mounted in the motor housing portion 118, as shown in Figs 2, 3 and 11, by support elements 134a and 134b acting between an outer surface 302 of the stator 132 and inner support surface 136 of the motor housing portion 118, which supporting elements 134a, 134b are spring-elastically deformable in a radial direction in relation to rotational axis 184 of drive shaft 142 and support the stator 132 relative to the inner support surface 136.

[0240] Preferably, each of the supporting elements 134, as shown for example in Figs 12 and 13, comprises spring-elastically deformable bodies 304 in a radial direction in relation to rotational axis 184, which bodies 304 for example support the stator 132 at the outer surface 302, and retaining elements 306 and 308 arranged on both sides of the spring-elastically deformable bodies 304, as considered in the direction of the rotational axis 184, and connecting the elastic bodies 304 to each other, which retaining elements 306, 308 are supported at the inner support surface 136 of the motor housing portion 118.

[0241] However, it is also possible for the retaining elements 306 and 308 to be supported at the outer surface 302 of the stator 132 and for the elastically deformable bodies 304 to be supported at the inner support surface 136 of the motor housing portion 118.

[0242] As shown by way of example in Figs 12 and 13 in conjunction with the supporting element 134a, these supporting elements 134a, 134b can be produced by a band material 310 in the form of an annular clasp with ends 312 which are spaced apart from one another, the edge regions 314 and 316 of which band material 310 form the retaining elements 306 and 308 and in the central region of which band material the elastically deformable bodies 304 are formed by structures impressed in the band material 310, which structures rise between the edge regions 314 and 316 and form support regions 322, which abut against the outer surface 302 of the stator 132 and in the peripheral direction around the rotational axis 184 are connected by means of rising flank regions 324 and 326, which run at an acute angle to the surface 136 supporting them, in Fig 13 at an acute angle to the statorreceiving surface, as foot regions 328 which abut against the stator-receiving surface 136, and in addition are connected to the edge regions 314 and 316, which likewise abut against the stator-receiving surface 136, in a direction parallel to the rotational axis 184 by means of flank regions 334 and 336 running at an acute angle to the supporting stator-receiving surface 136.

[0243] By forming the supporting elements 134 from a band material 310 with ends 312 spaced apart from one another, they can be inserted into the statorreceiving surface 136 without any material removal.

[0244] In particular, the flank regions 334 and 336 form insertion chamfers that allow for assembly or disassembly of the stator 132 without any material removal.

[0245] In particular, the supporting elements 134 allow the "hard" stator 132 to be mounted in the "soft" motor housing portion 118 made of light metal, in particular aluminum, without causing any damage to the motor housing portion 118; the same applies when replacing the electric motor 58.

[0246] Furthermore, the configuration of the tubular section 120 with a cross- sectional shape that is similar to circular-cylindrical is also advantageous in this case, since the forces required to receive the electric motor 58 and the compressive forces can also be optimally absorbed in the motor housing portion 118 in this case, in particular without any appreciable widening of the motor housing portion 118, so that, in turn, precise mounting of the electric motor 58 by the supporting elements 134 is possible.

[0247] Due to the flank regions 324 and 326 and also 334 and 336 running with a gentle gradient to the surface supporting them, in Fig 13 to the inner support surface 136, the spring-elastic deformation of the deformable bodies 304 occurs primarily in the flank regions 324, 326 and 334 and 336, as shown in Fig 13 at the flank regions 324 and 326 in a dashed manner.

[0248] Preferably, the spring-elastic bodies 304 are configured in such a way that they follow all variations of the radial spacing RA (Fig 13) between the outer surface 302 of the stator 132 and the inner support surface 136 by elastic deformation, without plastic deformations occurring in the region of the elastic bodies 304, in particular the flank regions 324, 326 as well as 334 and 336.

[0249] This makes it possible to keep the stator 132 always coaxial with the rotational axis 184, irrespective of the thermal and / or pressure-induced radial expansion of the motor housing portion 118 and the thermally induced radial expansion of the stator 132.

[0250] Such pressure-induced radial expansions of the motor housing portion 118 occur in particular because the motor chamber 116 the housing sleeve 16 of the overall housing 118 is made of light metal.

[0251] In addition to the pressure load on the motor housing portion 118, there is also thermal expansion depending on the operating state of the stator 132 and the motor housing portion 118.

[0252] Since all such deformations, which have the effect of changing the radial spacing RA, are absorbed by the spring-elastic bodies 304 in the form of purely elastic deformations, an optimally small gap 186 between the rotor 138 and the stator 132 being more or less the same in circumferential direction can be maintained regardless of the operating state of the refrigerant compressor.

[0253] Since all of the elastic elements 304 are arranged, for example, in a band material 310 and are held in their positions relative to each other by the retaining elements 306 and 308, the retaining elements 306 and 308 can be arranged running in a practically closed manner around the stator 132 in planes running perpendicular to the rotational axis 184, thereby holding the elastic elements 304 in defined positions relative to the outer side 302 of the stator 132 and to the inner support surface 136.

[0254] For exact positioning of the supporting elements 134 in the motor housing portion 118, a step 342 is preferably provided adjacently to the supporting wall 140, specifically on a side facing the drive chamber 146, which step 342 runs around the rotational axis 184 and serves to position one of the supporting elements 134b facing the drive chamber 146.

[0255] In order to be able to position the second supporting element 134a precisely relative to the first supporting element 134b, it would in principle be conceivable to also provide a step in the motor housing portion 118, but this would mean a further weakening of a wall thickness of the motor housing portion 118.

[0256] For this reason, a spacer element 344 is provided between the supporting elements 134a and 134b as shown in Fig 11, which spacer element 344, for example, abuts against the retaining elements 306 and 308 of the supporting elements 134a and 134b respectively and thus predetermines the exact position of the supporting element 134a relative to the supporting element 134b.

[0257] For example, the spacer element 344 is configured to abut against the statorreceiving surface 136 of the motor housing portion 118 and to run partially or completely around the rotational axis 184 to keep the supporting elements 134a and 134b in relatively precise positions throughout their extent around the rotational axis 184.

[0258] For example, the supporting elements 134 and / or the spacer element 344 are formed by annular sheet-metal elements, in particular made from band material 310, having ends 312 spaced apart from one another which tend to widen in the radial direction so that these sheet-metal elements automatically abut against the inner support surface 136 and are fixed by frictional engagement.

[0259] This allows the supporting elements 134 and, as applicable, the spacer element 344 to be inserted into the inner support surface 136 without material removal. As shown in Fig. 14, a second embodiment of the refrigerant compressor unit 54, the inner heat exchanger 34, and the first external heat exchanger 62 are arranged in a refrigerant circuit of refrigeration system 60, said second embodiment of a refrigerant circuit being denoted as a whole by 370.

[0260] The refrigerant circuit 370 is connected to a high pressure connection 372 of a second embodiment the refrigerant compressor unit 54', starting from which high- pressure connection a supply line 74 to the first external heat exchanger 62 leads, which heat exchanger 362 cools a total mass flow TMF of refrigerant, compressed to high pressure PH by the refrigerant compressor 54.

[0261] Also in this embodiment in case CO2 is used as refrigerant the refrigerant for example is present in a trans-critical state.

[0262] In this case, the refrigerant may be cooled in the first external high-pressure- side heat exchanger unit 62 either by ambient air, or also by contact with a heat-absorbing medium of any kind, for example also cooling water.

[0263] After the external heat exchanger 62, the total mass flow TMF supplied at the high-pressure connection 372 of the refrigerant compressor unit 54' in the refrigerant circuit 370 passes through, in the case of CO2 in a trans-critical state, an expansion member 376 arranged in the refrigerant circuit 370, is expanded by said expansion member 376 to an intermediate pressure IP, and then enters an intermediate-pressure collector 382, in which the total mass flow TMF cooled by expansion divides into a principal mass flow PMF of liquid refrigerant, which settles in the form of a liquid refrigerant bath 384 in the intermediate-pressure collector 382, and an auxiliary mass flow AMF, which forms a gas bubble 386 above the liquid bath 384.

[0264] The principal mass flow PMF of liquid refrigerant, starting from the intermediate-pressure collector 382, is supplied to a cooling stage 392, which comprises a cooling expansion member 394, which cools the principal mass flow PMF to a low pressure LP by expansion, and, starting from here, the principal mass flow PMF enters the internal low-pressure-side heat exchanger 34, in which due to the fact that refrigeration capacity has been made available, it is able to draw heat from the circulation flow 22 in the interior 18 of the cooling unit 10.

[0265] The principal mass flow PMF heated in heat exchanger 34 then enters the refrigerant compressor unit 54' at low pressure LP via a low-pressure connection 402.

[0266] The second embodiment of refrigerant compressor 56' of the refrigerant compressor unit 54', as shown in Fig. 14 is formed as a reciprocating compressor and preferably comprises a first compressor stage 412, formed by two cylinder units 414a and 414b, each driven by a cylinder drive 415a, 415b, in particular an eccentric drive, each of which draws in the refrigerant of the principal mass flow PMF from an inlet chamber 416a, 416b arranged in cylinder head 172 and delivers it for example into a common outlet chamber 418 arranged in cylinder head 172. In so doing, the first compressor stage 412 compresses the refrigerant from the principal mass flow PMF supplied to the first compressor stage 412 at low pressure LP, for example at values from 1 bar to 60 bar, to a medium pressure MP, which for example lies at values in the range of from 20 bar to 120 bar.

[0267] The principal mass flow PM compressed to a medium pressure MP is then supplied from a medium-pressure outlet 422 of the common outlet chamber 418 to a second external medium-pressure-side heat exchanger 424, which for example is likewise arranged in the equipment unit 52 and for example is likewise passed through by the external airflow 66.

[0268] Due to the second external medium-pressure-side heat exchanger 424, it is possible to cool the refrigerant of the principal mass flow PMF compressed to a medium pressure MP back to a temperature close to ambient temperature, and to remove again from said refrigerant a significant part of the heat supplied during the compression.

[0269] The cooled refrigerant of the principal mass flow PMF compressed to a medium pressure MP is supplied from the second external medium-pressure-side heat exchanger 424 to a medium-pressure inlet 428 of the refrigerant compressor unit 54' via a medium-pressure supply line 426, the medium-pressure inlet 428 being arranged on a motor housing portion 118' of compressor housing 110' of the second embodiment of refrigerant compressor unit 54'.

[0270] In addition, the medium-pressure supply line 426 is also connected to the intermediate-pressure collector 382, so that the auxiliary mass flow A from the intermediate-pressure collector 382 is supplied via the medium-pressure supply line 426 likewise to the medium-pressure connection 428 of the refrigerant compressor unit 54, and the medium pressure MP adjusts so that it corresponds to the intermediate pressure IP.

[0271] The medium-pressure inlet 428 is preferably arranged on the motor housing portion 108' which corresponds to the motor housing portion 108 of the first embodiment so that the incoming refrigerant enters motor chamber 116, passes through the motor chamber 116 whilst cooling the electric drive motor 58, which can correspond to the first embodiment 58 or the second embodiment 58' of the electric drive motor in particular whilst cooling rotor 138, 138' and a stator 132 of the electric drive motor 58, 58', and then enters a second compressor stage 442 of the refrigerant compressor unit 54'.

[0272] The second compressor stage 424 likewise comprises one cylinder unit 444 driven by a cylinder drive 445, in particular an eccentric drive, wherein the refrigerant compressed to a medium pressure MP and supplied to the second compressed stage 442 enters the cylinder unit 444 via an inlet chamber 446, is compressed in said cylinder unit, and then exists into an outlet chamber 448, which is connected to the high-pressure connection 32. In the second exemplary embodiment of the reciprocating compressor 56' according to the invention, the cylinder units 414a and 414b of the first compressor stage 412 and the cylinder unit 444 of the second compressor stage 442 are driven via common drive shaft 142, in particular a camshaft, which acts on the various cylinder drives 415a, 415b and 445, is preferably coaxially with and in particular integrally to drive shaft 142 of the rotor 138.

[0273] Furthermore, in the second exemplary embodiment of the refrigerant compressor unit 54', the cylinder drive chamber 456 receiving the drive shaft 142 and the cylinder drives 415a, 415b, 445 and bordering on the cylinder units 414a and 414b and also 444 is connected to the motor chamber 116 or transitions into the motor chamber 116, so that the cylinder drive chamber 146 is at medium pressure MP.

[0274] This has the advantage that, as a result, in particular at the second compressor stage 442, only pressure differences between medium pressure MP and high pressure HP occur in the cylinder unit 444, and therefore the loading of cylinder drives 445 for the cylinder unit 444a is lower than in the case of low pressure in the cylinder drive chamber 146.

[0275] Similarly, the medium pressure MP in the cylinder drive chamber 146 assists in supporting compressing of refrigerant at low pressure LP in the cylinder units 444a and 444b, in particular of the pistons thereof.

[0276] As shown in Fig. 15, the second embodiment of the refrigerant compressor unit 54' according to the invention, like the first embodiment is formed as a semi-hermetic compressor in which the refrigerant compressor 56' and the electric drive motor 58 are arranged in the compressor housing 110' which comprises a tubular section 120 end cover units 122 and 124 arranged on either side of the tubular section 120'.

[0277] In particular cylinder head 172' is arranged on the valve plate 162' are made of steel in accordance with the first embodiment 54 whereas the valve plate 162' is arranged on cylinder housing 156' formed integral with tubular section 120' and made of light metal and also cover units 122' and 124'.

[0278] With respect to the compressor housing 110' the tubular section 120' with cover units 122' and 124' as well as the support of the stator 132 or 132' in the motor housing portion 118 reference is made to the specification concerning the first embodiment.

[0279] In particular with respect to the design and operation of the electric drive motor 56 the second embodiment of the refrigerant compressor unit 54' can be provided with the rotor 138 and the stator 132 the design is identical with the design of the rotor 138 and the stator 132 according to the first embodiment of the electric drive motor 56 or as an alternative the design of the rotor 138' and the stator 132 according to the second embodiment of the electric drive motor 56'.

Claims

C L A I M S1. Compressor unit (54) for use with a cooling unit (10), comprising a compressor housing (110) provided with a motor housing portion (118) with an electric drive motor (58) arranged therein and a compressor housing portion (150) provided with a refrigerant compressor (56), wherein the electric drive motor (58) is a synchronous motor having a rotor (138) provided with a lamination stack (240, 270) with a plurality of magnet receptacles (252, 262) in which permanent magnets (250, 260) are arranged and wherein the electric drive motor (58) is driven by an inverter (112).

2. Compressor unit (54) according to claim 1, wherein the lamination stack (240, 270) is free of a squirrel cage.

3. Compressor unit (54) according to claim 1 or 2, wherein the lamination stack (240, 270) is arranged between closing plates (242, 244, 292, 294) closing the magnet receptacles (252, 262) in axial direction of the rotor (128, 138').

4. Compressor unit (54) according to claim 3, wherein the closing plates (242, 244, 292, 294) are connected by clamping pins (246, 296) extending through channels (248, 298) of the lamination stack (240, 270).

5. Compressor unit (54) according to one of the preceding claims, wherein the permanent magnets (250, 260) are permanent magnet plates having magnetic poles (N, S) on their opposite flat surfaces (154, 156, 164, 166).

6. Compressor unit (54) according to claim 5, wherein the permanent magnet plates (15) are oriented with their flat surfaces (254, 256)transverse to geometric radial directions (R) with respect to the rotational axis (184), the radial directions (R) intersecting the permanent magnet plates (250).

7. Compressor unit (54) according to one of the preceding claims, wherein the permanent magnets (250) are arranged in magnet receptacles (252) enclosed by the lamination stack (240) in geometric planes extending transverse to the rotational axis (184).

8. Compressor unit (54) according to claims 6 and 7, wherein in circumferential direction of the lamination stack (240) subsequent permanent magnets have alternating poles (N, S) on their sides opposite to the rotational axis (184).

9. Compressor unit (54) according to one of claims 6 to 8, wherein the permanent magnets are made of Nd-based material.

10. Compressor unit (54) according to one of claims 1 to 5, wherein the permanent magnets (260) are oriented with their flat surfaces (164, 166) parallel to a geometric radial direction (R) to the rotational axis (184).

11. Compressor unit (54) according to claim 10, wherein subsequent permanent magnets (160) in circumferential direction with respect to the rotational axis (184) have flat-surfaces (264, 266) facing each other with the same magnetic polarity (N, S).

12. Compressor unit (54) according to claim 10 or 11, wherein subsequent permanent magnets (260) in circumferential direction enclose a section (268) of the lamination stack (270) which guides magnetic flux lines (Fl) of the subsequent magnets (260) form their flat surfaces (264) in radial direction (R) towards the stator (132) or from the stator (132) in radial direction towards the flat surfaces (266).

13. Compressor unit (54) according to one of claims 10 to 12, wherein the magnet receptacles (262) of the lamination stack (270) are open in radial direction (R).

14. Compressor unit (54) according to claim 13, wherein the permanent magnets (260) are fixed in the magnet receptacles (262) of the lamination stack (270) by fingers (284, 286) extending over a portion of the respective end face (286, 288) of the respective permanent magnet (260) extending transverse to the radial direction.

15. Compressor unit (54) according to one of claims 10 to 14, wherein the sections (268) of the lamination stack (270) are fixed by radial connections (278) to a central portion (276) of the lamination stack (270) surrounding the drive shaft (142) and being supported by the drive shaft (142).

16. Compressor unit (54) according to one of claims 10 to 15, wherein the permanent magnets (260) are made of ferrite based material.

17. Compressor unit (54) according to claim 16, wherein the permanent magnets (260) have a residual magnetic flux density (Br) of more than 440mT.

18. Compressor unit (54) according to claim 16 or 17, wherein the permanent magnets have an intrinsic coercive force (Hcf) of more than 350 ka / m, preferably more than 400 ka / m, in a temperature range between -40°C to + 150°C.

19. Compressor unit (54) according to one of the preceding claims, wherein the compressor housing (110) is provided with a housing portion (108) on which the inverter (112) is mounted.

20. Compressor unit (54) according to claim 19, wherein the housing portion (108) is provided with a cooling passage (106) through which cooled refrigerant enters the compressor housing (110) for being compressed.

21. Compressor unit (54) according to claim 20, wherein power electronic components (114) of the inverter (112) are arranged in direct contact with the housing portion (108).

22. Compressor unit (54) according one of claims 19 to 21, wherein cooled refrigerant entering housing portion (108) leaves the housing portion (108) for cooling the electric drive motor (58) arranged in motor housing portion (118).

23. Compressor unit (54) according to one of the preceding claims, wherein refrigerant after cooling the electric drive motor (58) enters cylinder units (154a, 154b, 414a, 414b, 444) of the compressor (56) for being compressed therein.

24. Compressor unit (54) according to one of the preceding claims, wherein with the electric drive motor (58) arranged in the motor housing portion (118) the stator (132) is mounted in the motor housing portion (118) by means of supporting elements (134) inserted into the motor housing portion (118), which supporting elements (134) on the one hand abut against an inner support surface (136) of the motor housing portion (118) and on the other hand surround the stator (138) inserted into the supporting elements (134) on its outer surface (302) and support it spring-elastically relative to the inner support surface (136).

25. Compressor unit (54) according to claim 24, wherein the supporting elements (134) have spring-elastic bodies (304) which are dimensioned such that they are in an elastically deformed state in alloperating states of the motor housing portion (118) occurring during operation of the compressor unit (54).

26. Compressor unit (54) according to claim 24 or 25, wherein the supporting elements (134) are arranged running around the stator (132) and supporting the stator (132) at a plurality of locations on opposite sides of the axis of rotation (184) relative to the inner support surface (136) of the motor housing portion (118).

27. Compressor unit (54) according to one of claims 24 to 26, wherein the supporting elements (134) have elastic bodies (304) arranged at defined angular intervals around the rotational axis (184).

28. Compressor unit (54) according to claim 26 or 27, wherein the elastic bodies (304) are arranged to enable a flow of refrigerant along the outer surface (302) of the stator (132) and with a flow component in direction of the axis of rotation (184) for cooling the electric drive motor (58).

29. Compressor unit (54) according to one of claims 26 to 28, wherein the elastic bodies (304) are positioned relative to one another by a band material (310) positioning them relative to one another and running around the stator (132).

30. Compressor unit (54) according to one of claims 27 to 29, wherein the elastic bodies (304) are formed into the band material (310).

31. Compressor unit (54) according to one of claims 27 to 30, wherein the band material (310) is in the form of a ring-like clasp with open ends (312).

32. Compressor unit (54) according to one of claims 27 to 31, wherein the spring-elastic bodies (304) have flank regions (324, 326) running atan acute angle to the outer surface (302) of the stator (132) and / or to the inner support surface (136) between foot regions and support regions, one of which abuts against the outer surface (302) of the stator (132) and the other of which abuts against the inner support surface (136).

33. Compressor unit (54) according to one of claims 27 to 32, wherein the spring-elastic bodies (304) are successively formed into a springelastic band material (310) such that successive support regions abut against an outer surface (302) of the stator (138) or against the inner support surface (136) and successive foot regions abut against the inner support surface (136) or the outer surface (302) of the stator (132).

34. Compressor unit (54) according to one of claims 27 to 32, wherein the spring-elastic bodies (304) are located between edge regions (314, 316) arranged peripherally around the stator (132), and the support regions (322) are connected to the edge regions (314, 316) by means of flank regions (324, 326) running at an acute angle to the outer side of the stator (132) and / or to the inner support surface (136).

35. Compressor unit (54) according to claim 34, wherein, on the one hand, the support regions (322) abut against the outer surface (302) of the stator (132) or the inner support surface (136) and, on the other hand, the edge regions (314, 316) abut against the inner support surface (136) or the outer surface (302) of the stator (132).

36. Compressor unit (54) according to one of claims 24 to 35, wherein the supporting elements (134) are formed from a spring-elastic material, in particular spring steel.

37. Compressor unit (54) according to one of claims 24 to 36, wherein supporting elements (134) arranged successively in the direction ofthe rotational axis (184) are positioned spaced apart from one another in the motor housing portion (118) by a spacer element (344).

38. Compressor unit (54) according to claim 37, wherein one of the supporting elements (134) is positioned in respect of its position in the motor housing portion (118) by a step adjoining the inner support surface (136).

39. Compressor unit (54) according to one of the preceding claims, wherein the overall compressor housing (110) has a first cover unit (122) and a second cover unit (124), between which a tubular section (120) extends, which comprises the motor housing portion (118) in which the electric drive motor (58) is provided and the compressor housing portion (150) in which the refrigerant compressor (56) is provided.

40. Compressor unit (54) according to claim 39, wherein the tubular section (120) has an approximately cylindrical, shape.

41. Compressor unit (54) according to claim 39 or 40, wherein the compressor housing portion (150) comprises a cylinder housing (156) with a valve plate (162) and a cylinder head cover (172) arranged on said valve plate (162).

42. Compressor unit (54) according to one of claims 39 to 41, wherein the tubular section (120) comprising the cylinder housing (156) and the end cover units (122, 124) arranged on opposite sides thereof are made of light metal, in particular aluminum.

43. Compressor unit (54) according to claim 42, wherein the valve plate (162) and the cylinder head cover (172) are made of steel.

44. Compressor unit (54') according to one of the preceding claims, wherein the refrigerant compressor (56') has a first compressor stage (412) for compressing, to a medium pressure, refrigerant, in particular CO2, supplied at low pressure, and a second compressor stage (442) for compressing, to a high pressure (PH), the refrigerant, in particular CO2, that has been compressed to a medium pressure (PM), and wherein in particular the refrigerant compressor unit comprises a medium-pressure outlet (422) connected to the first compressor stage (412) and a medium-pressure inlet (428) connected to the second compressor stage (442).

45. Compressor unit (54') according to claim 44, wherein the mediumpressure inlet (428) opens out into a motor chamber (116) of the electric drive motor (58) for cooling the electric drive motor (58), and compressed refrigerant enters the second compressor stage (442) after having passed through the motor chamber (116).

46. Compressor unit (54') according to claim 44 or 45, wherein a drive chamber (146) of the refrigerant compressor (56'), from which the compressor stages (412, 442) are driven, is held at medium pressure (PM).

47. Compressor unit (54') according to claim 46, wherein the drive chamber (146) is connected to the motor chamber (116) via a connecting channel.

48. Compressor unit (54') according to one of claims 44 to 47, wherein the refrigerant compressor unit (54') is formed as a semi-hermetic compressor, wherein both, the electric drive motor (58) and the refrigerant compressor (56'), are arranged in an overall compressor housing (110) of the semi-hermetic compressor.

49. Compressor unit (54') according to one of claims 44 to 48, wherein the refrigerant compressor (56') is formed as a reciprocating compressor.

50. Compressor unit (54') according to claim 49, wherein the reciprocating compressor has a plurality of cylinder units (414, 444), of which at least one forms the first compressor stage (412) and at least one forms the second compressor stage (442).

51. Compressor unit (54') according to one of claims 44 to 50, wherein at least two cylinder units (414a, 414b) form the first compressor stage (412).

52. Compressor unit (54') according to one of claims 44 to 51, wherein a high-pressure connection (372) of the refrigerant compressor unit (54') is arranged on the cylinder head cover (172').

53. Compressor unit (54') according to one of claims 44 to 52, wherein a low-pressure connection of the refrigerant compressor unit (54') is arranged on the cylinder head cover (172').

54. Compressor unit (54') according to one of claims 44 to 53, wherein a medium-pressure outlet (422) of the refrigerant compressor unit (54') is arranged on the cylinder head cover (172').

55. Compressor unit (54') according to one of claims 44 to 54, wherein a medium-pressure inlet (428) of the refrigerant compressor unit (54') is arranged in the region of a motor housing portion (118)56. Compressor unit (54), according to one of the preceding claims, wherein refrigerant that is supplied to the refrigerant compressor (56) flows through the motor chamber (116) and there is formed in the motor chamber (116), on the bottom side, a lubricant sump (222) out of which lubricant is drawn off by suction by a suction-removal unit (210) and is transferred to a lubricant bath (194) in the motorchamber (116), wherein there is provided on the bottom side of the motor chamber (116) a receiving point (224) that takes a form such that, in particular in the event of tilting within a tilting tolerance range by the refrigerant compressor unit (54) relative to a starting position, the receiving point (224) receives lubricant from the lubricant sump (222) and supplies it to the suction-removal unit (210).

57. Compressor unit (54) according to claim 56, wherein the receiving point (224) forms a well in relation to the area surrounding it on the bottom side.

58. Compressor unit (54) according to claim 56 or 57, wherein the receiving point (224) is arranged in the motor chamber (116) such that, in the event of tilting of the refrigerant compressor unit (54), an axis of rotation (184) of a drive shaft (182) is within a tilting tolerance range of ±15° relative to a horizontal orientation in the starting position, the lubricant sump (222) extends as far as the receiving point (224) and lubricant from the lubricant sump (222) enters the receiving point (224).

59. Compressor unit (54) according to one of claims 56 to 58, wherein the receiving point (222) is arranged in a bottom region of the motor chamber (116) that runs from a supporting wall (140), which separates the motor chamber (116) from the drive chamber (116) to below a region of the stator (132) facing the supporting wall (140), and in particular runs for at most half of the extent of the stator (132) in direction of rotation (184).

60. Compressor unit (54) according to one of claims 56 to 59, wherein the receiving point (224) is formed in a recess relative to a bottom face of the motor chamber (116).

61. Compressor unit (54) according to claim 60, wherein the receiving point (224) is formed on a bottom body of the motor housing portion (118).

62. Compressor unit according to claim 61, wherein the receiving point (224) is shaped into the bottom body.

63. A refrigeration system (60), in particular a transport refrigeration system, comprising: a refrigerant circuit (370) in which there is guided a total mass flow (TMF) of refrigerant, a high-pressure-side heat exchanger (62) arranged in the refrigerant circuit (370) and cooling refrigerant compressed to a high pressure (HP), an expansion member (376), which is arranged in the refrigerant circuit (370) following on from the high-pressure-side heat exchanger (62) and in the active state cools the total mass flow (TMF) of the refrigerant by expansion and in so doing generates a principal mass flow (PMF) of liquid refrigerant and an auxiliary mass flow (AMF) of gaseous refrigerant, which enter an intermediate-pressure collector (382) and are separated therein into the principal mass flow (PMF) and the auxiliary mass flow (AMF), at least one cooling stage (392) which expands the principal mass flow (PMF) from the intermediate-pressure collector to low pressure (LP) in at least one cooling expansion member (394) and in so doing makes refrigerating capacity available at a low-pressure-side heat exchanger (34), and a refrigerant compressor unit (54') which compresses the principal mass flow (PMF) from a low pressure (LP) to a high pressure (HP), the refrigerant compressor unit (54') has a first compressor stage 412) for compressing to a medium pressure (MP) the refrigerant of the principal mass flow (PMF) supplied at low pressure (LP), and a second compressor stage (424) for compressing, to a high pressure (HP), therefrigerant of the principal mass flow (PMF) that has been compressed to a medium pressure (MP), and the auxiliary mass flow (AMF) from the intermediate-pressure collector (382) enters the second compressor stage (424) of the refrigerant compressor unit (54') for compressing to a high pressure (HP).

64. A refrigerant system according to claim 63, wherein the first compressor stage (412) of the refrigerant compressor unit (54') is connected to a medium-pressure-side heat exchanger (424), which cools the principal mass flow (PMF) that has been compressed to a medium pressure (MP) before said principal mass flow (PMF) enters the second compressor stage (424).

65. A refrigeration system according to claim 64, wherein the mediumpressure-side heat exchanger (424) is an external heat exchanger arranged outside the refrigerant compressor unit (54').

66. A refrigerant system according to one of claims 63 to 65, wherein the expansion member (376) expands the total mass flow (TMF) to an intermediate pressure (IP).

67. A refrigeration system according to claim 66, wherein the intermediate pressure (IP) corresponds substantially to the medium pressure (MP).

68. A refrigeration system according to one of claims 63 to 67, wherein the compressor unit (54') is a compressor unit according to claims 44 to 55 in particular also comprising the features on which claim 44 is dependent.

69. A refrigeration system, in particular a transport refrigeration system (60) comprising a refrigerant circuit (70) in which there is guided a total mass flow (TMF) of refrigerant, a high-pressure-side heat exchanger (62) arranged in the refrigerant circuit (70) and coolingrefrigerant compressed to high-pressure (HP), an expansion member (94) arranged in the refrigerant circuit (70) following on from the high- pressure-side heat exchanger (62) and expanding the total mass flow (TMF) to low pressure (LP) in at least one cooling expansion member (94) and in doing so make refrigerating capacity available at a low pressure-side heat exchanger (34) and a refrigerant compressor unit (54) according to at least one of claims 1 to 62, which compresses the total mass flow from low pressure (LP) to high pressure (HP).

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