Compressor housing

Abstract

A compressor motor housing 200 comprising: a first fluid passage 31 surrounding a motor volume 33 which receives the compressor motor, wherein the passage comprises a fluid chamber 35 extending away f

Description

The present disclosure relates to a housing for a compressor motor, particularly to a compressor motor for a compressor device used as part of a vapour-compression cycle to lower the temperature of a refrigerant. For example, the compressor device may be used as part of a thermal system for an electric vehicle. BACKGROUND Compressor devices may be used as part of vapour-compression cycles to lower the temperature of a refrigerant units to increase the temperature and pressure of refrigerant as part of the cycle. Compressor devices may be part of vapour-compression cycles used in thermal systems of electric vehicles. SUMMARY OF THE INVENTION Compressor devices (hereafter “compressors”) may be powered by a compressor motor which is configured to generate motion to cause the compressor to compress fluid flowing therethrough. For instance, centrifugal compressors use rotational motion generated by a motor to rotate an impeller, and axial compressors use rotational motion generated by a motor to rotate sets of blades. In either case the rotating component is to increase the kinetic and potential energy of a fluid flowing through the compressor so that its pressure and temperature increase. The use of a motor generates heat and examples herein relate to a compressor housing for cooling at least part of a compressor motor. According to an example of this disclosure there is provided a housing for cooling part of a compressor motor (e.g. a stationary component and / or a rotating component, for example a stator and / or a rotor), e.g. a motor of a compressor, or a motor to drive a compressor, the housing comprising a first fluid passage at least partially surrounding a motor volume configured to receive part of the compressor motor, the first fluid passage being configured for the flow of coolant therethrough. The first fluid passage comprises a fluid chamber extending away from the exterior surface of the housing in the radial direction or in the tangential direction, the tangential direction being perpendicular to the radial direction and the axial direction of the housing. The fluid chamber is configured to cool the motor volume, and therefore configured to cool at least part of the compressor motor (e.g. a part of a compressor motor received in the motor volume) and is further configured to cool a component, for example a component of a compressor unit, for example a printed circuit board (“PCB”) assembly and / or an inverter. The fluid chamber of the first fluid passage may extend in the radial direction and in the tangential direction. The fluid chamber of the first fluid passage may extend axially along the length of the housing. The length of the fluid chamber may be less than the length of the housing (although in some examples it may be substantially equal to the length of the housing). The housing may be cylindrical and a portion (e.g. some or all of) of the fluid chamber of the first fluid passage may takes (or form) the shape of a tangent plane to the exterior surface of the cylinder, but alternatively or additionally a portion of the fluid chamber may be U-shaped and / or L-shaped in other examples. In cylindrical housing examples, the width of the fluid chamber may be substantially equal to the diameter of the cylinder, although in other examples the width may be less than, or greater than, the diameter of the cylinder. The width of the fluid chamber may depend on the components that are to be cooled by the housing, e.g. the number of components of a printed circuit board). The fluid chamber may be configured to receive the component to be cooled, e.g. a printed circuit board, on an exterior surface thereof, for example a printed circuit board that is an inverter (e.g. comprising a number of field effect transistors that form the inverter). The housing may further comprise at least one fin protruding radially outwardly from an exterior surface of the housing and / or protruding radially inwardly from an interior surface of the housing. The one or more fins provide an increased (external or internal) surface area for cooling any fluid within the housing’s fluid passages. The fluid chamber may comprise the at least one fin in in some examples. The housing may further comprise a second fluid passage fluidically isolated from the first fluid passage, the second fluid passage comprising an inlet at a first side of the housing to receive refrigerant from a first side of the compressor and an outlet at a second side of the housing to discharge refrigerant to a second side of the compressor. The second fluid passage may extend axially along the length of the housing. At least a portion of the second fluid passage may be contained within the first fluid passage. At least a portion of the second fluid passage may be surrounded by the fluid chamber. The second fluid passage may comprise a serpentine, or tortuous, fluid passage (or path) through the fluid chamber. According to another aspect of this disclosure there is provided a compressor unit comprising the housing as described above and a printed circuit board. The printed circuit board may be disposed proximate the fluid chamber of the first coolant passage to facilitate heat transfer between the printed circuit board and the fluid chamber. The printed circuit board may comprise an inverter. According to another aspect of this disclosure there is provided a compressor unit comprising the housing as described above and a first compressor stage configured to receive refrigerant vapour, increase the pressure of the refrigerant vapour, and output the increased-pressure refrigerant vapour to the inlet of the second fluid passage, and a second compressor stage configured to receive refrigerant vapour from the outlet of the second fluid passage, increase the pressure of the refrigerant vapour, and output the increased-pressure refrigerant vapour. According to another aspect of this disclosure there is provided a housing for cooling part of a compressor motor, the housing comprising a first fluid passage at least partially surrounding a motor volume configured to receive part of the compressor motor, the first fluid passage being configured for the flow of coolant therethrough, and a second fluid passage fluidically isolated from the first fluid passage, the second fluid passage comprising an inlet at a first side of the housing to receive refrigerant from a first side of the compressor and an outlet at a second side of the housing to discharge refrigerant to a second side of the compressor. The second fluid passage may extend axially along the length of the housing. At least a portion of the second fluid passage may be contained within the first fluid passage. The second fluid passage may comprise a serpentine fluid passage through the fluid chamber. The housing may further comprise at least one fin protruding radially outwardly from an exterior surface of the housing to facilitate cooling of the housing and any fluid contained therein. The first fluid passage may comprise a fluid chamber extending away from the exterior surface of the housing in the radial direction or in the tangential direction of the housing, the tangential direction being perpendicular to both the radial and axial directions of the housing. The fluid chamber of the first fluid passage may extend in the radial direction and in the tangential direction. The fluid chamber of the first fluid passage may extends axially along the length of the housing. The length of the fluid chamber of the first fluid passage may be substantially equal to the length of the housing. The housing may be cylindrical. The fluid chamber of the first fluid passage may take the shape of a tangent plane to the exterior surface of the cylinder. The width of the fluid chamber may be substantially equal to the diameter of the cylinder. The fluid chamber of the first fluid passage may be symmetrical about the axial direction of the housing. At least a portion of the second fluid passage may be surrounded by the fluid chamber. The fluid chamber may be configured to receive a printed circuit board on an exterior surface thereof, for example a printed circuit board that is an inverter (e.g. comprising a number of field effect transistors that form the inverter). According to another example of the disclosure there is provided a compressor unit comprising the housing as described above and a first compressor stage configured to receive refrigerant vapour, increase the pressure of the refrigerant vapour, and output the increased-pressure refrigerant vapour to the inlet of the second fluid passage, and a second compressor stage configured to receive refrigerant vapour from the outlet of the second fluid passage, increase the pressure of the refrigerant vapour, and output the increased-pressure refrigerant vapour. According to another example of the disclosure there is provided a compressor unit comprising the housing as described above and a printed circuit board. The printed circuit board is disposed proximate the fluid chamber of the first coolant passage to facilitate heat transfer between the printed circuit board and the fluid chamber. BRIEF DESCRIPTION OF THE DRAWINGS Examples of the present disclosure will be described in detail with reference to the accompanying drawings, which should not be considered limiting, in which: Figure 1 schematically shows a compressor unit including a compressor housing, a compressor, and compressor motor; Figure 2 schematically shows a side cutaway through a compressor motor housing; Figure 3 schematically shows a perspective view of a compressor unit; Figures 4a-h schematically show example compressor motor housings to illustrate some of the principles of this disclosure; Figures 5a and 5b schematically show example compressor motor housings to illustrate some of the principles of this disclosure; Figures 6a and 6b schematically show example compressor motor housings to illustrate some of the principles of this disclosure; and Figures 7a-7c schematically show example compressor motor housings to illustrate some of the principles of this disclosure. DETAILED DESCRIPTION These drawings should not be considered limiting, rather they are used for explaining and understanding the present disclosure. Figure 1 schematically shows a compressor unit 1. The compressor unit 1 comprises a housing 100, which may be referred to as a central housing given its orientation in the compressor unit 1, and first and second end housing portions 11,12 (together termed “end housing”). The central housing 100 is located between the end housing portions 11, 12. The compressor unit 1 further comprises a first impeller 13 (which may be termed a first compressor “wheel”) and a first volute, or compressor chamber, 14. The volute, or compressor chamber 14, may be considered a chamber formed by the first end housing portion 11, e.g. integrally formed by the first end housing portion 11. Similarly, the compressor unit 1 comprises a second impeller 15 and a second volute 16. Together, the first impeller 13 and volute 14 may be referred to as a “compressor device” or “compressor.” Equally, the first and second impellers, and first and second volutes 13, 14, 15, 16, may be referred to as a “compressor device” or “compressor”. However, the terminology that is used herein is that, together, the first impeller 13 and the first volute 14 constitutes a first compressor stage at which a fluid flowing through the compressor unit 1 is compressed a first time, and the second impeller 15 and the second volute 16 constitutes a second compressor stage at which a fluid flowing through the compressor unit 1 is compressed a second time. The compressor unit 1 of the Figure 1 example may therefore be referred to as a two-stage compressor. The compressor unit 1 may be used as part of a vapour-compression cycle, e.g. to compress a refrigerant. Hereafter, the fluid flowing through the compressor unit 1 will be referred to as refrigerant but it should be appreciated that the compressor unit 1 is configured to receive, and compress, any fluid. The two compressor stages are configured to increase the pressure (and therefore the temperature) of a refrigerant flowing therethrough. For this purpose each impeller 13, 15 is configured to rotate and is driven to rotate by a compressor motor. More specifically, the compressor motor comprises a rotor 16 that surrounded by a stator 17 (although the stator may surround the rotor in other examples) and, each impeller 13, 15 is connected to the rotor 16 (e.g. by mounting to a common shaft). The compressor motor is driven by a supply of current to cause, via electromagnetic induction between the stator 17 and the rotor 16, the rotor 16 to rotate (or spin) within the stator 17. Thus, the motor drives the impellers 13, 15, to rotate which causes refrigerant to be compressed at the first and second compressor stages. The compressor unit 1 comprises first and second annular bearings 20, 21 (which may be air-foil bearings) which support the rotation of the rotor shaft 16 about the first and second compressor stages, respectively. Each annular bearing is supported by respective first and second bearing housings 22, 23. The compressor unit 1, more specifically the compressor housing 100, comprises an internal volume to receive the compressor motor (the compressor motor comprising at least the rotor 16 and the stator 17) and so housing 100 may be referred to as a compressor motor housing. The compressor unit 1 further comprises first and second annual seals 24, 25 which respectively seal the first and second compressor stages from this internal volume. A plate 26 is connected to the first bearing housing 21 and is configured to retain an axial annular bearing 27 which is to seal the internal volume. In operation, refrigerant flows through the first compressor stage, entering the compressor unit 1 via an inlet 18 whereupon it contacts the first, rotating, impeller 13. This increases the pressure of the refrigerant (therefore its energy and temperature) and forces the refrigerant centrifugally outward into the first volute chamber 14. This is referred to as compressing the refrigerant. The compressed refrigerant flows to the second compressor stage, via an interstage cooling passage 32 (to be described more fully below), where it is compressed, in a similar manner, again and compressed refrigerant (refrigerant at a higher pressure and temperature) is then output from then compressor unit 1 via an outlet 19. To drive the motor, AC current is supplied to the motor by an inverter 28. The inverter 28 in this example is located on top of the compressor unit 1, e.g. at a topside thereof. An electrical connection between the inverter and the motor is denoted by the dotted line 29. Specifically, the inverter receives DC current from a (not shown) source and converts this to AC current and drives the stator (e.g. according to a PWM duty cycle). The driven stator, via electromagnetic induction, causes the rotor to rotate which, in turn rotates the impellers 13, 14 to compress the refrigerant. The electrical connection between the inverter and the stator comprises a feedthrough 30 to mitigate for the pressure difference between the interior and exterior of the compressor unit 1. The inverter 28 may comprise at least one transistor (e.g. a MOSFET). The inverter 28 may comprise a printed circuit board (PCB). In use, the compressor motor and the inverter 28 generate heat. According to this disclosure the compressor motor housing 100 is configured to cool part of the compressor motor. Specifically, compressor housing 100 comprises a first fluid passage 31 configured for coolant to flow therethrough. As shown in Figure 1 the first fluid passage 31 is configured within the compressor housing 100 such that the first fluid passage 31 surrounds part of the motor volume (and therefore the stator and rotor when a motor is received in the motor volume). In this way, coolant flowing through the first fluid passage 31 cools part of the compressor motor (e.g. the stator or rotor or both). Put another way, coolant flowing in the first fluid passage will cool the internal volume that is to receive the compressor motor and will therefore cool anything received in the internal volume. When compressed refrigerant exits the first compressor stage, before it enters the second compressor stage it is referred to as “interstage refrigerant” (e.g. refrigerant that is between the stages). The compressor unit comprises an interstage fluid passage 32 which, according to this disclosure, is provided in the compressor motor housing 100 and fluidly connects the first and second compressor stages (more specifically, connects the first volute 14 with the second impeller 15). In the compressor unit 1 the first and second compressor stages are located at respective first and second ends of the compressor unit 1 and therefore the interstage refrigerant passage extends from a first side of the compressor housing to a second side of the compressor housing, connecting (and between) the first and second compressor stages. As will be described below, the first fluid passage 31 comprises a fluid chamber 35 configured to receive coolant, this part of the first fluid passage 31 being an increased-volume portion of the housing 10, and whose purpose may be to cool at least the inverter 28 and the interstage fluid passage 32 (and therefore any fluid contained in the interstage fluid passage 32). As the housing 100 comprises the first fluid passage 31 and the interstage fluid passage 32, the interstage fluid passage may therefore be referred to as a second fluid passage, the first fluid passage may be for receipt of coolant to cool the internal volume for receiving the compressor motor, and the second fluid passage may be for receipt of refrigerant, as described above. The housing 10 of this disclosure is therefore configured to receive first and second fluids in respective fluid passages. Figure 2 shows a perspective view of a compressor housing 200, which may comprise the housing 100 of Figure 1, but shown without the inverter 28 and without the motor being received in the housing to illustrate some of the principles of this disclosure. Figure 3 shows a schematic side cutaway through the compressor housing 200 to illustrate some of the principles of this disclosure. With reference to both Figures 2 and 3, the housing 200 defines a radial direction r, an axial direction z, and a tangential direction T. It will be seen that the tangential direction of the housing 10 may be the same as the radial direction for a specific radius but, in general, it is the direction that is perpendicular to both the axial and the radial directions of the housing 10. The tangential direction T is termed as such because an extension in the tangential direction is parallel to a tangent line (or plane), tangent to the exterior surface of the housing 10. The tangential direction T may also be referred to as a width direction, the axial direction being synonymous with a length direction. Although the housing is depicted as cylindrical herein (e.g. a housing whose lateral cross-sections are circular) this is by example only and other examples of the housing may not be cylindrical (e.g. the housing may take the form of a rectangular prism, e.g. a housing whose lateral cross-sections are square or rectangular, and the interior volume of such a rectangular prism may be itself a hollow rectangular prism or a hollow cylinder). In examples where the housing is non-cylindrical in particular, the radial direction may be referred to as the width direction. With no motor therein, the interior volume is shown in Figure 3 and is denoted by 33. As for Figure 1, the first fluid passage 31 comprises a portion of increased fluid volume, the fluid chamber 35. In the Figure 2 example the fluid chamber 35 has a planar, or flat, external surface 34. The planar external surface 34 of the fluid volume is configured to receive the inverter 28 thereon. In this way, the fluid chamber 35 provides a volume through which coolant can flow to cool the inverter 28. For this purpose, the fluid chamber 35 extends away from the exterior surface of the housing 10 in the radial direction or in the tangential direction, although in Figure 2 the fluid chamber 35 extends in both the radial and in the tangential directions. The first fluid passage 31 in this example extends axially along the length of the housing, e.g. in the direction z. The length of the fluid chamber 35 of the first fluid passage may be substantially equal to the length of the housing (as shown in Figure 2 or 3) or, alternatively the length of the fluid chamber 35 may be less than, or greater than, the length of the housing. In this example the housing is cylindrical. The fluid chamber 35 of the first fluid passage 31 takes the shape of a tangent plane (or tangent volume) to the exterior surface of the cylinder. This means that lateral cross-sections of the housing (as is shown in Figure 3) take the form of an Omega (Q) shape, the “prongs” of the Omega being the fluid chamber 35, and the Omega being closed. The width of the fluid chamber is substantially equal to the diameter of the cylinder in this example. The first fluid passage 31 may comprise a plurality of fluid chambers, which may be axial fluid chambers (extending along the length of the housing). The plurality of fluid chambers may be fluidically connected (in which case the first fluid passage 31 may comprise one inlet and one outlet) or may be distinct fluid chambers (in which case each fluid chamber may comprise its own inlet and outlet). The cross-section shown in Figure 2 illustrates that the first fluid passage 31 comprises a plurality of connected fluid chambers, and radially-projecting axial ribs are depicted in the cross section that partition the chambers (in this cross section, the chambers may be fluidically connected at a different axial location). The housing comprises at least one fin protruding radially outwardly from an exterior surface of the housing. This is schematically shown by the three fins 39 but it will be appreciated that any number of fins may be provided. The fins may comprise projections that protrude radially outwardly from the exterior surface of the housing and thereby increase the surface area of the external surface of the housing. The fins 39 may extend from the housing at regular, or irregular intervals. The fins 39 may be arranged in sets. The sets may extend from the housing at regular intervals (alternatively the exterior surface may comprise a plurality of extending fins which may extend continuously from the housing’s exterior surface and may be densely packed). The fins 39 increase the surface area of the external surface of the housing and therefore increase the surface area of the housing that is contact with the ambient air. Ambient air may cool the housing and therefore the fins provide an increased surface area of the housing that can be cooled by the ambient air. This in turn, improves heat transfer between the ambient air and the housing surface, which in turn aids to cool fluid in the first fluid passage 31. In this way the fins 39 may provide improved cooling of fluid in the first fluid passage 31 (and therefore also fluid in the second fluid passage 32 in examples which comprise the second fluid passage 32). The housing in the Figure 2 and 3 examples comprises the second fluid passage 32 which is fluidically isolated from the first fluid passage 31 and comprises an inlet 32a and an outlet (not shown). The inlet 32a may be located at a first side of the housing to receive refrigerant from a first side of the compressor (e.g. to receive refrigerant exiting the first stage of the compressor, e.g. received from the first volute 14) and the outlet may be located at a second side of the housing to discharge refrigerant to a second side of the compressor (e.g. to discharge refrigerant to the second stage of the compressor, e.g. to discharge refrigerant to the second impeller 15). In this way the housing may be configured such that the second fluid passage 32 is continuous with the first and second compressor stages. Put another way, the housing may be configured such that the second fluid passage 32 may be continuous with the fluid passage through the first impeller and first volute and the second impeller and second volute. The second fluid passage 32 in these examples extends axially along the length of the housing. The second fluid passage 32 may be straight, or may comprise a curve. The second fluid passage 32 may be straight from the inlet to the outlet. The inlet and outlet may be located at the same position in the radial and / or tangential directions, or they may be offset in the radial and / or tangential directions. At least a portion of the second fluid passage may be contained within the first fluid passage 31, for example within the fluid chamber 35 of the first fluid passage 31. In the Figure 2 and 3 examples the second fluid passage 32 is surrounded (e.g. fully surrounded) by the fluid chamber 35. The second fluid passage 32 may therefore be wholly, or completely, contained within the first fluid passage 31 (e.g. the fluid chamber 35 thereof). As shown in Figures 6a and 6b, to be described more fully later, the second fluid passage may comprise a serpentine, or tortuous, or non-straight, or curved fluid passage through the fluid chamber 25. For completeness, the second fluid passage 32 and the increased volume 35, whilst described and depicted together in the examples thus far, may not be practically implemented together according to examples of this disclosure. Indeed, this disclosure provides a housing comprising the first and second fluid passages 31, 32 with or without the first fluid passage 31 comprising the increased volume, the first fluid chamber, 35. This disclosure also provides a housing where the first fluid passage 31 comprises the increased volume, the first fluid chamber 35, with or without the second fluid passage 32. Figures 4a-h show other housings 400 that may comprise the housings 100 or 200 as described above. Each housing 400 comprises a first fluid passage 41 at least partially surrounding a motor volume 43 configured to receive part of the compressor motor, the first fluid passage 41 being configured for the flow of coolant therethrough as described above. The Figure 4a housing comprises the second, refrigerant, fluid passage 42, as described above but the first fluid passage 41 does not comprise a fluid chamber as described above. The first fluid passage 41 of the Figure 4b housing comprises the fluid chamber 45 as described above but not the second refrigerant fluid passage. The Figure 4c housing comprises both a fluid chamber 45 and a second refrigerant passage 42 but the second refrigerant passage 42 is not located within the fluid chamber 45. The first fluid passage 41 of the Figure 4d housing is comprises the fluid chamber 45 as described above but not the second refrigerant fluid passage (although it could comprise the second refrigerant passage in some examples), the purpose of Figure 4d being to illustrate a fluid chamber 45 that extends in the radial direction of the housing but not in the tangential direction. The first fluid passage 41 of the Figure 4e housing is comprises the fluid chamber 45 as described above but not the second refrigerant fluid passage (although it could comprise the second refrigerant passage in some examples), the purpose of Figure 4d being to illustrate a fluid chamber 45 that extends in the tangential direction of the housing but not in the radial direction. It will be appreciated that the fluid chamber 45 of Figure 4e extends to one side of the housing (to the right relative to the Figure), e.g. in a one direction, but may extend to the other side instead as well (e.g. may extend outward in both directions). The cross-sections of the Figure 4e housing are sigma (o) shaped. The first fluid passage 41 of the Figure 4f housing is comprises the fluid chamber 45 as described above but not the second refrigerant fluid passage (although it could comprise the second refrigerant passage in some examples), the purpose of Figure 4f being to illustrate an alternate-shaped fluid chamber 45, the fluid chamber 45 in this case comprising external fins configured as ridges , or discontinuities, for supporting the inverter 28. The advantage of the ridges (fins) being that the flow of coolant is permitted below the inverter 28 so as to enhance cooling. For the avoidance of doubt, these ridges should also be considered an example of the cooling fins (see element 39 in Figure 3 and elements 59 in Figures 5a and 5b) being provided on the housing, in this example the cooling fins being provided on an upper surface of the housing, and on an exterior surface of the fluid chamber 45. The Figure 4g housing comprises both a fluid chamber 45 and a second refrigerant passage 42. The second refrigerant passage 42 is located within the fluid chamber 45. The fluid chamber 45 in the Figure 4g example extends in the radial direction but not in the tangential direction and comprises a curved exterior surface. In this example the purpose of the fluid chamber 45 may be to cool a component other than the inverter or PCB etc. The first fluid passage 41 of the Figure 4h housing comprises the fluid chamber 45 as described above but not the second refrigerant fluid passage (although it could comprise the second refrigerant passage in some examples). The fluid chamber 45 of the Figure 4h housing defines an internal volume 46 of the first fluid passage 41 (this may be considered a second internal volume 46, the volume 43 being considered the first internal volume) configured to receive the inverter 28. In this way, the surface 42 of the first fluid passage 41 configured to receive the inverter 28 thereon comprises an internal, not an external, surface of the housing. In other words, the Figure 4h housing (specifically, the fluid chamber 45 thereof) is configured to receive the inverter therein. The volume 46 is at least partially surrounded by the first fluid passage 41 such that the inverter 28, when received in the volume 46, can be cooled from many directions. Figures 5a and 5b show two example housings 500 that may comprise any of the housings described above. The housings 500 of these examples show different configurations of the cooling fins 59. Figure 5a shows a densely-packed arrangement of cooling fins 59 (relative to the Figure 5b arrangement) whereas Figure 5b shows a sparse arrangement of cooling fins 59. Put another way, the Figure 5b housing comprises a set of cooling fins 59 spaced from one another at regular intervals, and the Figure 5a housing comprises multiple sets of cooling fins 59 (these sets may be spaced from one another at regular intervals). In examples where the first fluid chamber comprises the second internal volume (as for Figure 4h), the exterior surface of the second internal volume may comprise one or more cooling fins. Figures 6a-6b show two example housings 600 that may comprise any of the housings described above. Each of the housings 600 comprise the first fluid passage 61 for the flow of coolant therethrough, the first fluid passages 61 comprising the fluid volume 65. Each housing 600 comprises the second fluid passage 62 which in this example are substantially contained within the fluid volume 65. The purpose of Figures 6a-c is to show that in some examples the second fluid passage 62 may take, or form, a tortuous, or serpentine, path through the fluid volume 65, the paths being indicated by dotted lines. In Figure 6a, the path 62 is shown as a snake-like or serpentine or tortuous path from an inlet 62a to an outlet 62b. The Figure 6b path 62 is a zig-zag path from the inlet 62a to the outlet 62b. In each of the Figure 6a and 6b examples, the second fluid path 62 is not straight from the inlet 62a to the outlet 62b, which provides the second fluid path 62 with an increased surface area for contact by coolant in the fluid chamber 65, thereby enhancing the heat transfer between the surrounding coolant flowing through the fluid chamber 65 of the first fluid passage 61 and refrigerant in the second fluid passage 62. In other words, these examples may facilitate improved cooling of refrigerant in the second fluid passage 62 due to the increased length of the second fluid passage 62. The inlets and outlets 62a,b in these examples are offset in the tangential direction but in other examples they may not be offset. Figures 7a-7c show example housings 700 that may comprise any of the housings described above to illustrate alternative configurations of the fluid chamber, the component to be cooled by the fluid chamber, and an alternative configuration of the optional cooling fins. In this example the first and second fluid passages are shaded differently for illustration. Firstly, the Figures 7a-c examples show that the housing may comprise cooling fins 759 but, unlike the examples described above where the cooling fins are external to the housing, in these examples the cooling fins 759 are internal to the housing. More specifically, the housing 700 may comprise cooling fins 759 extending away from an interior surface of the housing and toward an interior of the housing. In the Figure 7a-c examples the cooling fins 759 protrude into the fluid chamber of the first fluid passage. In the Figure 7a-c examples the cooling fins 759 protrude into the fluid chamber from an upper internal surface of the housing 700. The Figure 7a-c housings 700 illustrate further shapes that the fluid chamber may take, and further illustrate how this could, in use, be in dependent on the component that the fluid chamber is to cool. Referring to Figure 7a, the housing 700 is to cool a PCB 761 an enlarged view of which is shown in Figure 7a. Figures 7a-c show cross-sections through the housing 700 and therefore cross-sections of the PCB 761. As discussed above the PCB 761 may be part of an inverter. The PCB comprises a number of transistors (e.g. MOSFETs) (e.g. a plurality thereof), indicated at 761, and a number of capacitors 763 (e.g. a plurality thereof) and it will be seen how the PCB 761 is oriented relative to the housing so that the PCB 761 (e.g. the components thereof - the one or more transistors 762 and the one or more capacitors 763) is cooled by fluid circulating in the first fluid passage (e.g. the fluid chamber thereof). It will be appreciated that the shape of the fluid chamber may conform, in some way, e.g. is based on, the PCB structure. In Figure 7a the fluid chamber is L-shaped although in other examples it may be differently shaped (e.g. II shaped), and the PCB 761 in this example comprises transistors 762 and capacitors 763 and may be considered a “full PCB assembly” hence the fluid chamber is shaped so as to cool the entire PCB in this example. The fluid chamber in Figure 7b is shaped differently as in this example only partial cooling of the PCB 761 is required, or the PCB may be considered a “partial PCB assembly”. The PCT 761 in the Figure 7c example only comprises transistors and therefore the fluid chamber is shaped so as to cool the transistors 762. The housing 700 comprises a cover 760 in these examples to protect the PCB assembly. Refrigerant (e.g. the fluid which may flow through the second fluid passage), may be considered a fluid capable of absorbing and releasing heat, and capable of undergoing a phase transition between liquid and gas states. Therefore, the second fluid passage may constitute part of a vapour-compression cycle. The refrigerant may be considered a to be a working fluid. It may be considered a cooling fluid. Coolant (e.g. the fluid which may flow through the first fluid passage) may be considered a cooling fluid capable of retaining a cold temperature for cooling a component (e.g. a physical component or another fluid). The coolant and refrigerant may both be considered working fluids. The person skilled in the art realizes that the present disclosure by no means is limited to what is explicitly described above. On the contrary, many modifications and variations are possible within the scope of the appended claims. Additionally, variations can be understood and effected by the skilled person in practicing the claimed invention, from a study of the 5 drawings, the disclosure, and the appended claims.

Claims

1. A housing for cooling part of a compressor motor, the housing comprising:a first fluid passage at least partially surrounding a motor volume configured to receive part of the compressor motor, the first fluid passage being configured for the flow of coolant therethrough, wherein the first fluid passage comprises a fluid chamber extending away from the exterior surface of the housing in the radial direction or in the tangential direction, the tangential direction being perpendicular to the radial direction and the axial direction of the housing.

2. The housing of claim 1 wherein the fluid chamber of the first fluid passage extends in the radial direction and in the tangential direction.

3. The housing of claim 1 or 2 wherein the fluid chamber of the first fluid passage extends axially along the length of the housing.

4. The housing of any preceding claim wherein the housing is cylindrical and wherein a portion of the fluid chamber of the first fluid passage takes the shape of a tangent plane to the exterior surface of the cylinder.

5. The housing of any preceding claim wherein a portion of the fluid chamber is L-shaped or U-shaped.

6. The housing of any preceding claim wherein the housing is cylindrical and wherein the width of the fluid chamber is substantially equal to the diameter of the cylinder.

7. The housing of any preceding claim wherein the fluid chamber is configured to receive a printed circuit board on an exterior surface thereof.

8. The housing of any preceding claim, further comprising at least one fin protruding radially outwardly from an exterior surface of the housing and / or protruding radially inwardly from an interior surface of the housing.

9. The housing of any preceding claim, further comprising a second fluid passage fluidically isolated from the first fluid passage, the second fluid passage comprising an inlet at a first side of the housing to receive refrigerant from a first side of thecompressor and an outlet at a second side of the housing to discharge refrigerant to a second side of the compressor.

10. The housing of claim 9, wherein the second fluid passage extends axially along the length of the housing.

11. The housing of claim 9 or 10 wherein at least a portion of the second fluid passage is contained within the first fluid passage.

12. The housing of any of claims 9-11 wherein at least a portion of the second fluid passage is surrounded by the fluid chamber.

13. The housing of any of claim 12 wherein the second fluid passage comprises a serpentine fluid passage through the fluid chamber.

14. A compressor unit comprising the housing of any preceding claim and: a printed circuit board,wherein the printed circuit board is disposed proximate the fluid chamber of the first coolant passage to facilitate heat transfer between the printed circuit board and the fluid chamber.

15. A compressor unit comprising the housing of any of claims 9-13 and:a first compressor stage configured to receive refrigerant vapour, increase the pressure of the refrigerant vapour, and output the increased-pressure refrigerant vapour to the inlet of the second fluid passage; anda second compressor stage configured to receive refrigerant vapour from the outlet of the second fluid passage, increase the pressure of the refrigerant vapour, and output the increased-pressure refrigerant vapour.AMENDMENTS TO THE CLAIMS HAVE BEEN FILED AS FOLLOWS:-CLAIMS1. A housing for cooling part of a compressor motor, the housing comprising:a first fluid passage at least partially surrounding a motor volume configured to receive part of the compressor motor, the first fluid passage being configured for the flow of coolant therethrough, wherein the first fluid passage comprises a fluid chamber extending away from the exterior surface of the housing in the radial direction or in the tangential direction, the tangential direction being perpendicular to the radial direction and the axial direction of the housing, the housing further comprising a second fluid passage fluidically isolated from the first fluid passage, the second fluid passage comprising an inlet at a first side of the housing to receive refrigerant from a first side of the compressor and an outlet at a second side of the housing to discharge refrigerant to a second side of the compressor.

2. The housing of claim 1 wherein the fluid chamber of the first fluid passage extends in the radial direction and in the tangential direction.

3. The housing of claim 1 or 2 wherein the fluid chamber of the first fluid passage extends axially along the length of the housing.

4. The housing of any preceding claim wherein the housing is cylindrical and wherein a portion of the fluid chamber of the first fluid passage takes the shape of a tangent plane to the exterior surface of the cylinder.

5. The housing of any preceding claim wherein a portion of the fluid chamber is L-shaped or U-shaped.

6. The housing of any preceding claim wherein the housing is cylindrical and wherein the width of the fluid chamber is substantially equal to the diameter of the cylinder.

7. The housing of any preceding claim wherein the fluid chamber is configured to receive a printed circuit board on an exterior surface thereof.

8. The housing of any preceding claim, further comprising at least one fin protruding radially outwardly from an exterior surface of the housing and / or protruding radially inwardly from an interior surface of the housing.

9. The housing of any preceding claim, wherein the second fluid passage extends axially along the length of the housing.

10. The housing of any preceding claim, wherein at least a portion of the second fluid passage is contained within the first fluid passage.

11. The housing of any preceding claims, wherein at least a portion of the second fluid passage is surrounded by the fluid chamber.

12. The housing of any preceding claim, wherein the second fluid passage comprises a serpentine fluid passage through the fluid chamber.

13. A compressor unit comprising the housing of any preceding claim and: a printed circuit board,wherein the printed circuit board is disposed proximate the fluid chamber of the first coolant passage to facilitate heat transfer between the printed circuit board and the fluid chamber.

14. A compressor unit comprising the housing of any preceding claim and:a first compressor stage configured to receive refrigerant vapour, increase the pressure of the refrigerant vapour, and output the increased-pressure refrigerant vapour to the inlet of the second fluid passage; anda second compressor stage configured to receive refrigerant vapour from the outlet of the second fluid passage, increase the pressure of the refrigerant vapour, and output the increased-pressure refrigerant vapour.

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